diff --git "a/magnetic_oxides_-_abstract.csv" "b/magnetic_oxides_-_abstract.csv"
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+publicationDate,title,abstract,id
+2008-12-07,Current-induced reversal in magnetic nanopillars passivated by silicon,"We demonstrate that magnetic multilayer nanopillars can be efficiently
+protected from oxidation by coating with silicon. Both the protected and the
+oxidized nanopillars exhibit an increase of reversal current at cryogenic
+temperatures. However the magnetic excitation onset current increases only in
+the oxidized samples. We show that oxidized nanopillars exhibit anomalous
+switching statistics at low temperature, providing a simple test for the
+quality of magnetic nanodevices.",0812.1381v1
+2017-12-10,Visible evidence to magnetism of graphene oxide,"Graphene oxide continues to amaze scientific community for multiple
+potentials in a broad span of applications such as catalysts, adsorbents,
+oxidants, etc., determined by constant unveiling of its fantastic natures. Of
+them, magnetism is not ultimately identified and directly observed by naked
+eyes. Herein, we report graphene oxide directionally migrated and deposited
+together simply under external magnetic field from common Nd-Fe-B magnet,
+whereas the ferromagnetism of graphene oxide did not exhibit that strong as
+iron. Therefore, we illustrated this interesting pathway to keep close to such
+2D carbon materials and potentially promoted magnetic-oriented applications.",1712.03570v4
+2007-06-20,Oxide spintronics,"Concomitant with the development of metal-based spintronics in the late
+1980's and 1990's, important advances were made on the growth of high-quality
+oxide thin films and heterostructures. While this was at first motivated by the
+discovery of high-temperature superconductivity in perovskite Cu oxides, this
+technological breakthrough was soon applied to other transition metal oxides,
+and notably mixed-valence manganites. The discovery of colossal
+magnetoresistance in manganite films triggered an intense research activity on
+these materials, but the first notable impact of magnetic oxides in the field
+of spintronics was the use of such manganites as electrodes in magnetic tunnel
+junctions, yielding tunnel magnetoresistance ratios one order of magnitude
+larger than what had been obtained with transition metal electrodes. Since
+then, the research on oxide spintronics has been intense with the latest
+developments focused on diluted magnetic oxides and more recently on
+multiferroics. In this paper, we will review the most important results on
+oxide spintronics, emphasizing materials physics as well as spin-dependent
+transport phenomena, and finally give some perspectives on how the flurry of
+new magnetic oxides could be useful for next-generation spintronics devices.",0706.3015v1
+2010-11-17,Magnetotransport and spin dynamics in an electron gas formed at oxide interfaces,"We investigate the spin-dependent transport properties of a two-dimensional
+electron gas formed at oxides' interface in the presence of a magnetic field.
+We consider several scenarios for the oxides' properties, including oxides with
+co-linear or spiral magnetic and ferroelectric order. For spiral multiferroic
+oxides, the magnetoelectric coupling and the topology of the localized magnetic
+moments introduce additional, electric field controlled spin-orbit coupling
+that affects the magneto-oscillation of the current. An interplay of this
+spin-orbit coupling, the exchange field, and of the applied magnetic field
+results in a quantum, gate-controlled spin and charge Hall conductance.",1011.3924v1
+2009-06-23,Strain-induced ferroelectricity in simple rocksalt binary oxides,"The alkaline earth binary oxides adopt a simple rocksalt structure and form
+an important family of compounds because of their large presence in the earth's
+mantle and their potential use in microelectronic devices. In comparison to the
+class of multifunctional ferroelectric perovskite oxides, however, their
+practical applications remain limited and the emergence of ferroelectricity and
+related functional properties in simple binary oxides seems so unlikely that it
+was never previously considered. Here, we show using first-principles density
+functional calculations that ferroelectricity can be easily induced in simple
+alkaline earth binary oxides such as barium oxide (BaO) using appropriate
+epitaxial strains. Going beyond the fundamental discovery, we show that the
+functional properties (polarization, dielectric constant and piezoelectric
+response) of such strained binary oxides are comparable in magnitude to those
+of typical ferroelectric perovskite oxides, so making them of direct interest
+for applications. Finally, we show that magnetic binary oxides such as EuO,
+with the same rocksalt structure, behave similarly to the alkaline earth
+oxides, suggesting a route to new multiferroics combining ferroelectric and
+magnetic properties.",0906.4235v1
+2015-12-06,Magnetic properties of bismuth-cobalt oxides doped by erbium,"We synthesized bismuth - cobalt oxide doped by erbium with general formula
+Bi3-xErxCoO3-y. Compound has structure of delta-form bismuth oxide. Magnetic
+properties of the compound were measured by Faraday's method using quartz
+scales in the temperature range of 80-500 K. The magnetic susceptibility and
+effective magnetic moment were calculated.",1512.01782v1
+2011-10-27,Magnetically Controlling the Explosion of Dirac Fermions during the Oxidation of Graphene,"The different physical properties of multilayered graphene or graphite
+relative to single layer graphene result from the Dirac spins symmetry in
+graphene and the Pauli spin symmetry in graphite. The Dirac symmetry in
+multilayers of graphene (graphite) is hindered by interlayer interactions.
+Different magnetizations, electronics and chemistry of graphite and graphene
+follow from absence of interlayer interactions in graphene. The distinct
+kinetics and dynamics of graphite and graphene by oxidation by the Hummer's
+method in weak external magnetic field are observed in this work. Graphite
+manifest enhanced non-explosive oxidation of Pauli spins in weak magnetic field
+with background paramagnetic oxygen slowing the magnetic acceleration. Graphene
+and graphite oxide manifest explosive oxidation and magnetically decelerated
+explosive oxidation of Dirac spins in weak magnetic field for temperatures
+below 20 oCelsius. The explosive oxidation of graphene and its deceleration in
+weak external magnetic field are interpreted resulting from the giant
+nonlocality and spin Hall Effect in the chemically reacting graphene. This is
+the first identification, analysis and interpretation of the chemistry of the
+Dirac spins and the magnetochemistry of relativistic electrons.",1110.6060v1
+2018-07-31,Spin absorption at ferromagnetic-metal/platinum-oxide interface,"We investigate the absorption of a spin current at a
+ferromagnetic-metal/Pt-oxide interface by measuring current-induced
+ferromagnetic resonance. The spin absorption was characterized by the magnetic
+damping of the heterostructure. We show that the magnetic damping of a
+Ni$_{81}$Fe$_{19}$ film is clearly enhanced by attaching Pt-oxide on the
+Ni$_{81}$Fe$_{19}$ film. The damping enhancement is disappeared by inserting an
+ultrathin Cu layer between the Ni$_{81}$Fe$_{19}$ and Pt-oxide layers. These
+results demonstrate an essential role of the direct contact between the
+Ni$_{81}$Fe$_{19}$ and Pt-oxide to induce sizable interface spin-orbit
+coupling. Furthermore, the spin-absorption parameter of the
+Ni$_{81}$Fe$_{19}$/Pt-oxide interface is comparable to that of intensively
+studied heterostructures with strong spin-orbit coupling, such as an oxide
+interface, topological insulators, metallic junctions with Rashba spin-orbit
+coupling. This result illustrates strong spin-orbit coupling at the
+ferromagnetic-metal/Pt-oxide interface, providing an important piece of
+information for quantitative understanding the spin absorption and spin-charge
+conversion at the ferromagnetic-metal/metallic-oxide interface.",1807.11806v1
+2014-06-24,Atomistic calculation of the thickness and temperature dependence of exchange coupling through a dilute magnetic oxide,"The exchange coupling of two magnetic layers via a diffuse oxide interlayer
+is studied with an atomistic spin model. We investigate the effect of magnetic
+concentration and oxide layer thickness on the effective exchange coupling
+strength and find an exponential dependence of the coupling strength on the
+oxide thickness without the need for magnetic pinholes. Furthermore we show
+that exchange coupling has a strong temperature dependence which is significant
+for the reversal dynamics during heat assisted magnetic recording.",1406.6214v1
+2023-06-19,Unveiling the nucleation and growth of Zr oxide precipitates of internally oxidized Nb3Sn superconductors,"We report on atomic-scale analyses of nucleation and growth of Zr oxide
+precipitates and the microstructural evolution of internally oxidized Nb3Sn
+wires for high-field superconducting magnet applications, utilizing atom probe
+tomography (APT), transmission electron microscopy (TEM), and first-principles
+calculations. APT analyses reveal that prior to interfacial reactions at
+Nb/Nb3Sn interfaces, Zr atoms in an unreacted Nb-1Zr-4Ta (at.%) alloy form
+clusters with O atoms owing to their high affinity for oxygen and are
+segregated at grain boundaries (GBs) in the Nb grains. Then, nucleation of Zr
+oxide precipitates occurs in Nb3Sn and at Nb3Sn/Nb interfaces, driven by the
+small solubility of Zr and O in Nb3Sn compared to Nb. Quantitative APT and TEM
+analyses of Zr oxide precipitates in Nb3Sn layers demonstrate the nucleation,
+growth, and coarsening processes of Zr oxide precipitates in Nb3Sn layers. A
+high number density of Zr oxide nanoprecipitates is observed in the Nb3Sn
+layers, ~10^23 per m^3, with a mean precipitate diam. <10 nm at 625 oC and 700
+oC, which provide pinning centers for grain refinement of Nb3Sn, <100 nm diam.,
+and serve as pinning sites for fluxons. First-principles calculations and
+classical nucleation theory are employed to describe the nucleation of Zr oxide
+precipitates in Nb3Sn: energy barriers and the critical radius for nucleation
+of Zr oxide precipitates in Nb3Sn. Our research yields the kinetic pathways for
+nucleation and growth of Zr oxide precipitates and the microstructural
+evolution of Nb3Sn layers, which helps to improve the fabrication process of
+internally oxidized Nb3Sn wires for high-field superconducting magnets.",2306.10866v2
+2021-11-10,Dependence of magnetic domain patterns on plasma-induced differential oxidation of CoPd thin films,"We demonstrate the evolution of the micro-patterned magnetic domains in CoPd
+thin films pretreated with e-beam lithography and O2 plasma. During the
+days-long oxidation, significantly different behaviors of the patterned
+magnetic domains under magnetization reversal are observed via magneto-optic
+Kerr effect microscopy on different days. The evolution of the magnetic
+behaviors indicate critical changes in the local magnetic anisotropy energies
+due to the Co oxides that evolve into different oxide forms, which are
+characterized by micro-area X-ray absorption spectroscopy and X-ray
+photoelectron spectroscopy. The coercive field of the area pre-exposed to
+plasma can decrease to a value 10 Oe smaller than that unexposed to plasma,
+whereas after a longer duration of oxidation the coercive field can instead
+become larger in the area pre-exposed to plasma than that unexposed, leading to
+an opposite magnetic pattern. Various forms of oxidation can therefore provide
+an additional dimension for magnetic-domain engineering to the current
+conventional lithographies.",2111.05767v1
+2004-10-29,Magnetic properties of polypyrrole - coated iron oxide nanoparticles,"Iron oxide nanoparticles were prepared by sol -gel process. Insitu
+polymerization of pyrrole monomer in the presence of oxygen in iron oxide
+ethanol suspension resulted in a iron oxide - polypyrrole nanocomposite. The
+structure and magnetic properties were investigated for varying pyrrole
+concentrations. The presence of the gamma - iron oxide phase and polypyrrole
+were confirmed by XRD and FTIR respectively. Agglomeration was found to be
+comparatively much reduced for the coated samples, as shown by TEM. AC
+susceptibility measurements confirmed the superparamagnetic behaviour.
+Numerical simulations performed for an interacting model system are performed
+to estimate the anisotropy and compare favourably with experimental results.",0410760v1
+2023-10-03,The effect of surface oxidation and crystal thickness on magnetic properties and magnetic domain structures of Cr2Ge2Te6,"Van der Waals (vdW) magnetic materials such as Cr2Ge2Te6 (CGT) show promise
+for novel memory and logic applications. This is due to their broadly tunable
+magnetic properties and the presence of topological magnetic features such as
+skyrmionic bubbles. A systematic study of thickness and oxidation effects on
+magnetic domain structures is important for designing devices and vdW
+heterostructures for practical applications. Here, we investigate thickness
+effects on magnetic properties, magnetic domains, and bubbles in
+oxidation-controlled CGT crystals. We find that CGT exposed to ambient
+conditions for 5 days forms an oxide layer approximately 5 nm thick. This
+oxidation leads to a significant increase in the oxidation state of the Cr
+ions, indicating a change in local magnetic properties. This is supported by
+real space magnetic texture imaging through Lorentz transmission electron
+microscopy. By comparing the thickness dependent saturation field of oxidized
+and pristine crystals, we find that oxidation leads to a non-magnetic surface
+layer which is thicker than the oxide layer alone. We also find that the stripe
+domain width and skyrmionic bubble size are strongly affected by the crystal
+thickness in pristine crystals. These findings underscore the impact of
+thickness and surface oxidation on the properties of CGT such as saturation
+field and domain/skyrmionic bubble size and suggest a pathway for manipulating
+magnetic properties through a controlled oxidation process.",2310.02319v2
+2005-04-07,Magnetic oxide semiconductors,"Magnetic oxide semiconductors, oxide semiconductors doped with transition
+metal elements, are one of the candidates for a high Curie temperature
+ferromagnetic semiconductor that is important to realize semiconductor
+spintronics at room temperature. We review in this paper recent progress of
+researches on various magnetic oxide semiconductors. The magnetization,
+magneto-optical effect, and magneto-transport such as anomalous Hall effect are
+examined from viewpoint of feasibility to evaluate the ferromagnetism. The
+ferromagnetism of Co-doped TiO2 and transition metal-doped ZnO is discussed.",0504168v1
+2010-11-10,Repair of magnetism in oxidized graphene nanoribbons,"Novel route for the establishing of magnetism in realistic oxidized graphene
+nanoribbons is proposed. Modelling of the migration of hydroxyl groups from
+central part to the zig-zag edges of graphene nanoribbons passivated by oxygen
+are performed with using density functional theory. The presence of hydroxyl
+groups near the edges leads formation of dangling bonds there instead saturated
+due to oxidation and repairs of magnetism diminished by edges oxidation. The
+route of manufacturing and stability of new type of magnetic graphene
+nanoribbons are also discussed.",1011.2342v1
+2017-03-19,Surface anisotropy of iron oxide nanoparticles and slabs from first principles : influence of coatings and ligands as a test of the Heisenberg model,"We performed ab initio computations of the magnetic properties of simple iron
+oxide clusters and slabs. We considered an iron oxide cluster functionalized by
+a molecule or glued to a gold cluster of the same size. We also considered a
+magnetite slab coated by cobalt oxide or a mixture of iron oxide and cobalt
+oxide. The changes in magnetic behavior were explored using constrained
+magnetic calculations. A possible value for the surface anisotropy was
+estimated from the fit of a classical Heisenberg model on ab initio results.
+The value was found to be compatible with estimations obtained by other means,
+or inferred from experimental results. The addition of a ligand, coating, or of
+a metallic nanoparticle to the systems degraded the quality of the description
+by the Heisenberg Hamiltonian. Proposing a change in the anisotropies allowing
+for the proportion of each transition atom we could get a much better
+description of the magnetism of series of hybrid cobalt and iron oxide systems.",1703.06414v1
+2015-09-06,Electrical control of magnetism in oxides,"This review article aims at illustrating the recent progresses in the
+electrical control of magnetism in oxides with profound physics and enormous
+potential applications. In the first part, we provide a comprehensive summary
+of the electrical control of magnetism in the classic multiferroic
+heterostructures and clarify their various mechanisms lying behind. The second
+part focuses on the novel route of electric double layer gating for driving a
+significantly electronic phase transition in magnetic oxides by a small
+voltage. The electric field applied on the ordinary dielectric oxide in the
+third part is used to control the magnetic phenomenon originated from the
+charge transfer and orbital reconstruction at the interface between dissimilar
+correlated oxides. At last, we analyze the challenges in electrical control of
+magnetism in oxides, both on mechanism and practical application, which would
+inspire more in-depth researches and advance the development in this field.",1509.01795v1
+2011-12-04,Spintronic oxides grown by laser-MBE,"The recent study of oxides led to the discovery of several new fascinating
+physical phenomena. High-temperature superconductivity, colossal
+magnetoresistance, dilute magnetic doping, or multiferroicity were discovered
+and investigated in transition-metal oxides, representing a prototype class of
+strongly correlated electronic systems. This development was accompanied by an
+enormous progress regarding thin film fabrication. Within the past two decades,
+epitaxial thin films with crystalline quality approaching semiconductor
+standards became available using laser molecular beam epitaxy. This evolution
+is reviewed, particularly with emphasis on transition-metal oxide thin films,
+their versatile physical properties, and their impact on the field of
+spintronics. First, the physics of ferromagnetic half-metallic oxides, such as
+the doped manganites, the double perovskites and magnetite is presented
+together with possible applications based on magnetic tunnel junctions. Second,
+the wide bandgap semiconductor zinc oxide is discussed particularly with regard
+to the controversy of dilute magnetic doping with transition-metal ions and the
+possibility of realizing p-type conductivity. Third, the field of oxide
+multiferroics is presented with the recent developments in single-phase
+multiferroic thin film perovskites as well as in composite multiferroic
+hybrids.",1112.0751v1
+2020-04-25,"Effects of Oxidation of Top and Bottom Interfaces on the Electric, Magnetic, and Spin-Orbit Torque Properties of Pt/Co/AlOx Trilayers","Oxidation strongly influences the properties of magnetic layers employed in
+spintronic devices. We study the effect of oxidation on the structural,
+magnetic, and electrical properties as well as current-induced spin-orbit
+torques (SOTs) in Pt/Co/AlOx, Pt/CoOx/Co/AlOx, and PtOx/Co/AlOx layers. We show
+how the saturation magnetization, perpendicular magnetic anisotropy, anomalous
+Hall resistance, and SOT are systematically affected by the degree of oxidation
+of both the Pt/Co and Co/Al interfaces. Oxidation of the Co/Al interface
+results in a 21% and 42% variation of the dampinglike and fieldlike SOT
+efficiencies, which peak at 0.14 and 0.07, respectively. The insertion of a
+paramagnetic CoOx layer between Pt and Co maintains a very strong perpendicular
+magnetic anisotropy and improves the dampinglike and fieldlike SOT
+efficiencies, up to 0.26 and 0.20, respectively. In contrast with recent
+reports, we do not find that the oxidation of Pt leads to a significant
+enhancement of the torques. Rather, we find that oxygen migrates from Pt to the
+Co and Al layers, leading to a time-dependent oxidation profile and an
+effective spin Hall conductivity that decreases with increasing oxygen
+concentration. Finally, we study current-induced switching in Pt/Co/AlOx with
+different degrees of oxidation and find a linear relationship between the
+critical switching current and the effective magnetic anisotropy controlled by
+the oxidation of Al. These results highlight the importance of interfaces and
+oxidation effects on the SOT and magnetotransport properties of heavy
+metal/ferromagnet/oxide trilayers and provide information on how to improve the
+SOT efficiency and magnetization-switching characteristics of these systems.",2004.12115v1
+2020-11-20,An Investigation of Commercial Iron Oxide Nanoparticles: Advanced Structural and Magnetic Properties Characterization,"Magnetic nanoparticles (MNPs) have been extensively used as tiny heating
+sources in magnetic hyperthermia therapy, contrast agents in magnetic resonance
+imaging (MRI), tracers in magnetic particle imaging (MPI), carriers for
+drug/gene delivery, etc. There have emerged many magnetic
+nanoparticle/microbeads suppliers since the last decade, such as Ocean
+NanoTech, Nanoprobes, US Research Nanomaterials, Miltenyi Biotec, micromod
+Partikeltechnologie GmbH, and nanoComposix, etc. In this paper, we report the
+physical and magnetic characterizations on iron oxide nanoparticle products
+from Ocean NanoTech. Standard characterization tools such as Vibrating-Sample
+Magnetometer (VSM), X-Ray Diffraction (XRD), Dynamic Light Scattering (DLS),
+Transmission Electron Microscopy (TEM), and Zeta Potential Analyzer are used to
+provide magnetic nanoparticle customers and researchers with an overview of
+these iron oxide nanoparticle products. In addition, the dynamic magnetic
+responses of these iron oxide nanoparticles in aqueous solutions are
+investigated under low and high frequency alternating magnetic fields, giving a
+standardized operating procedure for characterizing the MNPs from Ocean
+NanoTech, thereby yielding the best of magnetic nanoparticles for different
+applications.",2011.10215v1
+2023-04-01,High-quality NiFe thin films on oxide/non-oxide platforms via pulsed laser deposition at room temperature,"Soft ferromagnetic NiFe thin films are promising for applications in
+spintronic devices because of their constituent electrical and magnetic
+properties. Electron beam evaporation and sputtering techniques have been used
+to deposit NiFe thin films. For in-situ stacking of NiFe with functional
+complex oxides, the pulsed laser deposition (PLD) method is highly desirable.
+However, the growth of high-quality NiFe (and non-oxide thin films in general)
+by PLD remains a formidable task. Here, we report high-quality NiFe thin films
+of various thicknesses on oxide/non-oxide substrates with desirable magnetic
+properties by PLD at room temperature. The magnetic properties are found to be
+strongly dependent on the laser fluence of the deposition process. The laser
+fluence of 4 Joule/cm$^2$ produces the highest magnetization of ~547 emu/cc.
+The small coercivity (few Oersted) and sharp ferromagnetic switching behaviour
+indicate uniaxial anisotropy with an easy axis along the in-plane direction. In
+addition, thickness-dependent magnetodynamics characterizations are studied via
+ferromagnetic resonance. Our findings indicate the ferromagnetic
+characteristics are sensitive to the quality of the oxide/non-oxide substrate
+surface. These results offer significant insight into the PLD-based development
+of thin metal magnetic films.",2304.00357v1
+2010-04-30,Magnetic structure of the edge-sharing copper oxide chain compound NaCu2O2,"Single-crystal neutron diffraction has been used to determine the
+incommensurate magnetic structure of NaCu2O2, a compound built up of chains of
+edge-sharing CuO4 plaquettes. Magnetic structures compatible with the lattice
+symmetry were identified by a group-theoretical analysis, and their magnetic
+structure factors were compared to the experimentally observed Bragg
+intensities. In conjunction with other experimental data, this analysis yields
+an elliptical helix structure in which both the helicity and the polarization
+plane alternate among copper-oxide chains. This magnetic ground state is
+discussed in the context of the recently reported multiferroic properties of
+other copper-oxide chain compounds.",1004.5526v1
+2020-04-02,Quantum transport evidence of Weyl fermions in an epitaxial ferromagnetic oxide,"Magnetic Weyl fermions, which occur in magnets, have novel transport
+phenomena related to pairs of Weyl nodes, and they are, of both, scientific and
+technological interest, with the potential for use in high-performance
+electronics, spintronics and quantum computing. Although magnetic Weyl fermions
+have been predicted to exist in various oxides, evidence for their existence in
+oxide materials remains elusive. SrRuO3, a 4d ferromagnetic metal often used as
+an epitaxial conducting layer in oxide heterostructures, provides a promising
+opportunity to seek for the existence of magnetic Weyl fermions. Advanced oxide
+thin film preparation techniques, driven by machine learning technologies, may
+allow access to such topological matter. Here we show direct quantum transport
+evidence of magnetic Weyl fermions in an epitaxial ferromagnetic oxide SrRuO3:
+unsaturated linear positive magnetoresistance (MR), chiral-anomaly-induced
+negative MR, Pi Berry phase accumulated along cyclotron orbits, light cyclotron
+masses and high quantum mobility of about 10000 cm2/Vs. We employed
+machine-learning-assisted molecular beam epitaxy (MBE) to synthesize SrRuO3
+films whose quality is sufficiently high to probe their intrinsic quantum
+transport properties. We also clarified the disorder dependence of the
+transport of the magnetic Weyl fermions, and provided a brand-new diagram for
+the Weyl transport, which gives a clear guideline for accessing the
+topologically nontrivial transport phenomena. Our results establish SrRuO3 as a
+magnetic Weyl semimetal and topological oxide electronics as a new research
+field.",2004.00810v2
+1997-08-22,Estimation of the Doping Dependence of Antiferromagnetism in the Copper Oxide Material,"Within the $t$-$J$ model, we study the doping dependence of
+antiferromagnetism in the copper oxide materials by considering quantum
+fluctuations of spinons in the random-phase-approximation. The staggered
+magnetization vanishes around doping $\delta=5%$ for a reasonable parameter
+value $t/J=5$, which is in agreement with the experiments on copper oxide
+materials.",9708176v1
+2012-01-26,Superconductivity in the metallic-oxidized magnesium interface,"Metastable superconductivity at 39 - 54 K in the interfaces formed by
+metallic and oxidized magnesium (MgO) has been observed by ac magnetic
+susceptibility measurements. The superconducting interfaces have been produced
+by the surface oxidation of metallic magnesium under special conditions.",1201.5468v1
+2003-05-19,Exploration of oxide-based diluted magnetic semiconductors toward transparent spintronics,"A review is given for the recent progress of research in the field of
+oxide-based diluted magnetic semiconductor (DMS), which was triggered by
+combinatorial discovery of transparent ferromagnet. The possible advantages of
+oxide semiconductor as a host of DMS are described in comparison with
+conventional compound semiconductors. Limits and problems for identifying novel
+ferromagnetic DMS are described in view of recent reports in this field.
+Several characterization techniques are proposed in order to eliminate
+unidentified ferromagnetism of oxide-based DMS (UFO). Perspectives and possible
+devices are also given.",0305435v1
+2013-02-14,Anamolous reduction of magnetic coercivity of graphene oxide and reduced graphene oxide upon cooling,"In this report we present the temperature evolution of magnetic coercivity of
+graphene oxide (GO) and reduced graphene oxide (RGO). We report an anamolous
+decrease in coercivity of GO and RGO with decreasing temperature. We could
+explain this anamolous behavior invoking the inherent presence of ripple in
+graphene. We observe antiferromagnetic and ferromagnetic behavior at room
+temperature for GO and RGO respectively, but at low temperatures both shows
+paramagnetic behavior.",1302.3336v1
+2022-07-13,Boosting spin-orbit torque efficiency in spin-current generator/magnet/oxide superlattices,"Efficient manipulation of magnetic materials is essential for spintronics. In
+spin-current generator/magnet bilayers, the efficiency of spin-orbit torques
+per magnetic layer thickness scales inversely with the magnetic layer
+thickness, leading to considerable power increase in applications with large
+magnetic layer thickness. Here, we develop a 3D spin-orbit material scheme in
+which the spin torque efficiency can be remarkably boosted up by stacking
+[spin-current generator/magnet/oxide]n superlattices, with the oxide layers
+breaking the inversion symmetry. In contrast, the spin torque diminishes in
+[spin-current generator/magnet]n superlattices lacking inversion symmetry
+breaking. These results advances the understanding of spin-orbit torques in
+magnetic multilayers and establishes spin-current generator/magnet/oxide
+superlattices as advantageous bricks for development of high energy-efficiency,
+high-endurance, and high-density spintronic memory and computing.",2207.05968v2
+2016-06-28,Termination control of magnetic coupling at a complex oxide interface,"Atomically flat interfaces between ternary oxides have chemically different
+variants, depending on the terminating lattice planes of both oxides.
+Electronic properties change with the interface termination which affects, for
+instance, charge accumulation and magnetic interactions at the interface.
+Well-defined terminations have yet rarely been achieved for oxides of ABO3 type
+(with metals A, B). Here, we report on a strategy of thin film growth and
+interface characterization applied to fabricate the La0.7Sr0.3MnO3-SrRuO3
+interface with controlled termination. Ultra-strong antiferromagnetic coupling
+between the ferromagnets occurs at the MnO2-SrO interface, but not for the
+other termination, in agreement with density functional calculations. X-ray
+magnetic circular dichroism measurements reveal coupled reversal of Mn and Ru
+magnetic moments at the MnO2-SrO interface. Our results demonstrate termination
+control of magnetic coupling across a complex oxide interface and provide a
+pathway for theoretical and experimental explorations of novel electronic
+interface states with engineered magnetic properties.",1606.08687v1
+2018-04-06,Magnetic exchange fields and domain wall superconductivity at an all-oxide superconductor / ferromagnet insulator interface,"At a superconductor-ferromagnet (S/F) interface, the F layer can introduce a
+magnetic exchange field within the S layer, which acts to locally spin split
+the superconducting density of states. The effect of magnetic exchange fields
+on superconductivity has been thoroughly explored at S-ferromagnet insulator
+(S/FI) interfaces for isotropic s-wave S and a thickness that is smaller than
+the superconducting coherence length. Here we report a magnetic exchange field
+effect at an all-oxide S/FI interface involving the anisotropic d-wave high
+temperature superconductor praseodymium cerium copper oxide (PCCO) and the FI
+praseodymium calcium manganese oxide (PCMO). The magnetic exchange field in
+PCCO, detected via magnetotransport measurements through the superconducting
+transition, is localized to the PCCO/PCMO interface with an average magnitude
+that depends on the presence or absence of magnetic domain walls in PCMO. The
+results are promising for the development of all-oxide superconducting
+spintronic devices involving unconventional pairing and high temperature
+superconductors.",1804.02094v2
+2020-01-31,Magnetic properties of rare earth and transition metal based perovskite type high entropy oxides,"High entropy oxides (HEO) are a recently introduced class of oxide materials,
+which are characterized by a large number of elements (i.e. five or more)
+sharing one lattice site which crystallize in a single phase structure. One
+complex example of the rather young HEO family are the rare-earth transition
+metal perovskite high entropy oxides. In this comprehensive study, we provide
+an overview over the magnetic properties of three perovskite type high entropy
+oxides. The compounds have a rare-earth site which is occupied by five
+different rare-earth elements, while the transition metal site is occupied by a
+single transition metal. In this way a comparison to the parent binary oxides,
+namely the orthocobaltites, -chromites and -ferrites is possible. X-ray
+absorption near edge spectroscopy (XANES), magnetometry and M\""ossbauer
+spectroscopy are employed to characterize these complex materials.
+  In general, we find surprising similarities to the magnetic properties of the
+binary oxides, despite the chemical disorder on the rare-earth site. However
+distinct differences and interesting magnetic properties are also observed such
+as noncollinearity, spin reorientation transitions as well as large coercive
+fields of up to 2\,T at ambient temperature. Both the chemical disorder on the
+RE A-site, and the nature of the TM on the B-site play an important role in the
+physical properties of these high entropy oxides.",2002.00026v1
+2019-08-06,The complex non-collinear magnetic orderings in Ba2YOsO6: A new approach to tuning spin-lattice interactions and controlling magnetic orderings in frustrated complex oxides,"Frustrated magnets are one class of fascinating materials that host many
+intriguing phases such as spin ice, spin liquid and complex long-range magnetic
+orderings at low temperatures. In this work we use first-principles
+calculations to find that in a wide range of magnetically frustrated oxides, at
+zero temperature a number of non-collinear magnetic orderings are more stable
+than the type-I collinear ordering that is observed at finite temperatures. The
+emergence of non-collinear orderings in those complex oxides is due to
+higher-order exchange interactions that originate from second-row and third-row
+transition metal elements. This implies a collinear-to-noncollinear spin
+transition at sufficiently low temperatures in those frustrated complex oxides.
+Furthermore, we find that in a particular oxide Ba$_2$YOsO$_6$, experimentally
+feasible uniaxial strain can tune the material between two different
+non-collinear magnetic orderings. Our work predicts new non-collinear magnetic
+orderings in frustrated complex oxides at very low temperatures and provides a
+mechanical route to tuning complex non-collinear magnetic orderings in those
+materials.",1908.01916v1
+2021-08-30,Magnetic Suboxides as a Source of Two-Level System Losses in Superconducting Niobium,"We identify one potential source of quantum decoherence in three-dimensional
+superconducting radio-frequency (SRF) resonators and two-dimensional transmon
+qubits that utilize oxidized niobium: magnetic suboxides which drive two-level
+system (TLS) losses. By probing the effect of sequential \textit{in situ}
+vacuum baking treatments on the RF peformance of bulk Nb SRF resonators and on
+the oxide structure of a representative Nb sample within a time-of-flight
+secondary ion mass spectrometer (TOF-SIMS), we find a non-monotonic evolution
+of cavity quality factor $Q_0$ which correlates with the interplay of
+TLS-hosting magnetic suboxide generation and oxide dissolution. We localize
+this effect to the oxide itself and present the non-role of diffused
+interstitial oxygen in the underlying Nb by regrowing a new oxide \textit{via}
+chemistry and wet oxidation which reveals a mitigation of aggravated TLS
+losses.",2108.13352v2
+2022-08-25,Berry curvature induced anomalous Hall conductivity in magnetic topological oxide double perovskite Sr2FeMoO6,"Oxide materials exhibit several novel structural, magnetic, and electronic
+properties. Their stability under ambient conditions, easy synthesis, and high
+transition temperatures provide such systems with an ideal ground for realizing
+topological properties and real-life technological applications. However,
+experimental evidence of topological states in oxide materials is rare. In this
+study, we have synthesized single crystals of oxide double perovskite Sr2FeMoO6
+and revealed its topological nature by investigating its structural, magnetic,
+and electronic properties. We observed that the system crystallized in the
+cubic space group Fm-3m, which is a half-metallic ferromagnet. Transport
+measurements show an anomalous Hall effect, and it is evident that the Hall
+contribution originates from the Berry curvature. Assuming a shift of the Fermi
+energy towards the conduction band, the contribution of the anomalous Hall
+effect is enhanced owing to the presence of a gaped nodal line. This study can
+be used to explore and realize the topological properties of bulk oxide
+systems.",2208.11988v1
+2022-09-14,Absence of a pressure gap and atomistic mechanism of the oxidation of pure Co nanoparticles,"We present a detailed atomistic picture of the oxidation mechanism of Co
+nanoparticles and its impact on magnetism by experimentally following the
+evolution of the structure, chemical composition, and magnetism of individual,
+gas-phase grown Co nanoparticles during controlled oxidation. The early stage
+oxidation occurs in a twostep process characterized by (i) the initial
+formation of small CoO crystallites randomly distributed across the
+nanoparticle surface, until their coalescence leads to structural completion of
+the oxide shell and passivation of the metallic core; (ii) progressive
+conversion of the CoO shell to Co3O4, accompanied by void formation due to the
+nanoscale Kirkendall effect. The Co nanoparticles remain highly reactive toward
+oxygen during phase (i), demonstrating the absence of a pressure gap whereby a
+low reactivity at low pressures is postulated. Our results provide an important
+benchmark for an improved understanding of the magnetism of oxidized cobalt
+nanoparticles, with potential implications on their performance in catalytic
+reactions.",2209.06949v1
+2020-06-11,Embracing defects and disorder in magnetic nanoparticles,"Iron oxide nanoparticles have tremendous scientific and technological
+potential in a broad range of technologies, from energy applications to
+biomedicine. To improve their performance, single-crystalline and defect-free
+nanoparticles have thus far been aspired. However, in several recent studies
+defect-rich nanoparticles outperform their defect-free counterparts in magnetic
+hyperthermia and magnetic particle imaging. Here, an overview on the
+state-of-the-art of design and characterization of defects and resulting spin
+disorder in magnetic nanoparticles is presented with a focus on iron oxide
+nanoparticles. The beneficial impact of defects and disorder on intracellular
+magnetic hyperthermia performance of magnetic nanoparticles for drug delivery
+and cancer therapy is emphasized. Defect-engineering in iron oxide
+nanoparticles emerges to become an alternative approach to tailor their
+magnetic properties for biomedicine, as it is already common practice in
+established systems such as semiconductors and emerging fields including
+perovskite solar cells. Finally, perspectives and thoughts are given on how to
+deliberately induce defects in iron oxide nanoparticles and their potential
+implications for magnetic tracers to monitor cell therapy and immunotherapy by
+magnetic particle imaging.",2006.06474v1
+2019-04-22,Stripe structures in phase separated magnetic oxides,"We investigate the phase separated inhomogeneous charge and spin states in
+magnetic oxides. In particular, we study one dimensional harmonic waves and
+stripe structures. We show that harmonic spin charge waves are unstable and
+inevitably transform into two or three dimensional structures, while the stripe
+structures can be stable for certain parameters. Such stripe structures may
+allow the control of magnetic state with electric field in a magnetic oxide
+thin film.",1904.10053v1
+1997-06-06,Charge Fluctuations and Magnetic Inelastic Neutron Scattering in Copper-Oxide high -Tc superconductors,"Spin subsystem of the copper oxides within the polar Jahn-Teller centers
+model corresponds to a singlet-triplet magnet where the local boson movement
+accompanied by the induced longitudinal spin fluctuations. These fluctuations
+determine the features of the magnetic inelastic scattering in the high-Tc
+cuprates.",9706054v1
+2001-10-15,"Synthesis, Crystal Structure and Magnetic Properties of the Linear-Chain Cobalt Oxide Sr5Pb3CoO12","The novel spin-chain cobalt oxide Sr5Pb3CoO12 [P-62m, a = 10.1093(2) A and c
+= 3.562 51(9) A at 295 K] is reported. Polycrystalline sample of the compound
+was studied by neutron diffraction (at 6 and 295 K) and magnetic susceptibility
+measurements (5 to 390 K). The cobalt oxide was found to be analogous to the
+copper oxide Sr5Pb3CoO12, which is comprised of magnetic-linear chains at
+inter-chain distance of 10 A. Although the cobalt oxide chains (mu_eff of 3.64
+mu_B per Co) are substantially antiferromagnetic (theta_W = -38.8 K), neither
+low-dimensional magnetism nor long-range ordering has been found; a
+local-structure disorder in the chains might impact on the magnetism. This
+compound is highly electrically insulating.",0110292v1
+2021-01-19,Tunable Rashba spin-orbit coupling and its interplay with multiorbital effect and magnetic ordering at oxide interfaces,"The complex oxide heterostructures such as LaAlO3/SrTiO3 (LAO/STO) interface
+are paradigmatic platforms to explore emerging multi-degrees of freedom
+coupling and the associated exotic phenomena. In this study, we reveal the
+effects of multiorbital and magnetic ordering on Rashba spin-orbit coupling
+(SOC) at the LAO/STO (001) interface. Based on first-principles calculations,
+we show that the Rashba spin splitting near the conduction band edge can be
+tuned substantially by the interfacial insulator-metal transition due to the
+multiorbital effect of the lowest t_2g bands. We further unravel a competition
+between Rashba SOC and intrinsic magnetism, in which the Rashba SOC induced
+spin polarization is suppressed by the interfacial magnetic ordering. These
+results deepen our understanding of intricate electronic and magnetic
+reconstruction at the perovskite oxide interfaces and shed light on the
+engineering of oxide heterostructures for all-oxides-based spintronic devices.",2101.07586v1
+2008-03-25,Superconductivity at 43 K in Samarium-arsenide Oxides $SmFeAsO_{1-x}F_x$,"Since the discovery of high-transition temperature ($T_c$) superconductivity
+in layered copper oxides, extensive efforts have been devoted to explore the
+higher $T_c$ superconductivity. However, the $T_c$ higher than 40 K can be
+obtained only in the copper oxide superconductors so far. The highest reported
+value of $T_c$ for non-copper-oxide bulk superconductivity is 39 K in
+$MgB_2$.\cite{jun} The $T_c$ of about 40 K is close to or above the theoretical
+value predicted from BCS theory.\cite{mcmillan} Therefore, it is very
+significant to search for non-copper oxide superconductor with the transition
+temperature higher than 40 K to understand the mechanism of high-$T_c$
+superconductivity. Here we report the discovery of bulk superconductivity in
+samarium-arsenide oxides $SmFeAsO_{1-x}F_x$ with ZrCuAiAs type structure.
+Resistivity and magnetization measurements show strong evidences for transition
+temperature as high as 43 K. $SmFeAsO_{1-x}F_x$ is the first non-copper oxide
+superconductor with $T_c$ higher than 40 K. The $T_c$ higher than 40 K may be a
+strong argument to consider $SmFeAsO_{1-x}F_x$ as an unconventional
+superconductor.",0803.3603v2
+2020-03-09,Chemical instability of free-standing boron monolayers and properties of oxidized borophene sheets,"In this work we report results of step-by-step modeling of the oxidation of
+free-standing boron monolayers of different types. Results of the calculations
+demonstrate that the process of the oxidation is always exothermic and lead
+toward the formation of foam-like boron oxide films with incorporated
+non-oxidized small boron clusters. Some of these boron-oxide films demonstrate
+the presence of chemically stable magnetic centers. Evaluation of the physical
+properties of oxidized boprophene sheets (OBS) demonstrate it possible
+application in solar energy, as sensors and coating against leakage of
+hydrogen.",2003.03937v1
+2024-04-02,Quantum Hall effect in a CVD-grown oxide,"Two-dimensional electron systems (2DES) are promising for investigating
+correlated quantum phenomena. In particular, 2D oxides provide a platform that
+can host various quantum phases such as quantized Hall effect,
+superconductivity, or magnetism. The realization of such quantum phases in 2D
+oxides heavily relies on dedicated heterostructure growths. Here we show the
+integer quantum Hall effect achieved in chemical vapor deposition grown Bi2O2Se
+- a representative member of a more accessible oxide family. A single or few
+sub-band 2DES can be prepared in thin films of Bi2O2Se, where the film
+thickness acts as the sole design parameter and the sub-band occupation is
+determined by the electric field effect. This new oxide platform exhibits
+characteristic advantages in structural flexibility due to its layered nature,
+making it suitable for scalable growth. The unique small mass distinguishes
+Bi2O2Se from other high-mobility oxides, providing a new platform for exploring
+quantum Hall physics in 2D oxides.",2404.02104v1
+2022-12-29,Magnetic oxides,"In this article we give a general survey of the main properties of magnetic
+oxides - mostly the oxides of transition metals, but sometime also containing
+rare earths ions. This is a very rich class of materials, among which there are
+insulators and metals, systems with insulator-metal transitions, and there are
+among them even high-temperature superconductors. One of the main features of
+these compounds, which attract to them special attention and which serve as a
+basis of many applications, are their rich magnetic properties. In this article
+we discuss the main physical effects determining their behaviour, and describe
+in detail especially their magnetic properties, but not only. After shortly
+discussing the basic structure of isolated magnetic ions, we concentrate on the
+collective effects depending on the interaction between sites, especially
+exchange interaction, giving rise to different magnetic properties: different
+types of magnetic ordering in conventional systems, but also more exotic states
+such as spin liquid states in frustrated systems. We also cover related
+phenomena in magnetic oxides, such as magnetoelectric and multiferroic
+behaviour, and discuss at the end their diverse useful properties serving as a
+basis of many applications.",2212.14176v1
+2019-12-03,Contact resistivity due to oxide layers between two REBCO tapes,"In a no-insulation (NI) REBCO magnet, the turn-to-turn contact resistivity
+(Rc) determines its quench self-protection capability, charging delay time and
+the energy loss during field ramps. Therefore it is critically important to be
+able to control a range of Rc values suitable for various NI magnet coils. We
+used a commercial oxidizing agent Ebonol C to treat the copper surface of REBCO
+tapes. The copper oxide layer was characterized by cross-sectional transmission
+electron microscopy (TEM) and x-ray photoelectron spectroscopy (XPS). The oxide
+layer formed in Ebonol C at 98 {\deg}C for 1 min is Cu2O of about 0.5 um. The
+Rc between two oxidized REBCO is in the order of 35 mOhm-cm2 at 4.2 K which
+decreases slowly with contact pressure cycles. The Rc increases but only
+slightly at 77 K. We also investigated the effect of oxidation of stainless
+steel co-wind tape on Rc. The native oxides on 316 stainless steel tape as well
+as those heated in air at 200 - 600 {\deg}C were examined by TEM and XPS. The
+native oxides layer is about 3 nm thick. After heating at 300 {\deg}C for 8 min
+and 600 {\deg}C for 1 min, its thickness increases to about 10 and 30 nm
+respectively. For the stainless steel tapes with about 10 nm surface oxides,
+pressure cycling for 30,000 cycles decreases Rc by almost 4 orders of
+magnitude. Whereas at 77 K, it only changes slightly. For a surface with 30 nm
+oxide, the Rc decreases moderately with load cycles. The results suggest that
+for an oxidized stainless steel to achieve stable Rc over large number of load
+cycles a relatively thick oxide film is needed.",1912.01515v1
+2022-08-09,Valence state and lattice incorporation of Ni in Zn/Co-based magnetic oxides,"Ni incorporation has been studied in a comprehensive range of Zn/Co-based
+magnetic oxides to elucidate it valence state and lattice incorporation. The
+resulting structural and magnetic properties are studied in detail. To the one
+end Ni in incorporated by in-diffusion as well as reactive magnetron
+co-sputtering in wurtzite ZnO where only the Ni-diffused ZnO exhibits
+significant conductivity. This is complemented by Ni and Co codoping of ZnO
+leading. To the other end, the ZnCo$_2$O$_4$ spinel is co-doped with varying
+amounts of Ni. In the wurtzite oxides Ni is exclusively found on tetrahedral
+lattice sites in its formal 2+ oxidation state as deep donor. It behaves as an
+anisotropic paramagnet and a limited solubility of Ni about 10\% is found. Due
+to its smaller magnetic moment it can induce partial uncompensation of the Co
+magnetic moments due to antiferromagnetic coupling. In the spinel Ni is found
+to be incorporated in its formal 3+ oxidation state on octahedral sites and
+couples antiferromagnetically to the Co moments leading again to magnetic
+uncompensation of the otherwise antiferromagnetic ZnCo$_2$O$_4$ spinel and to
+ferrimagnetism at higher Ni concentrations. Increasing Ni even further leads to
+phase separation of cubic NiO resulting in an exchange-biased composite
+magnetic oxide.",2208.11086v1
+2007-04-16,Enhanced Half-Metallicity in Edge-Oxidized Zigzag Graphene Nanoribbons,"We present a novel comprehensive first-principles theoretical study of the
+electronic properties and relative stabilities of edge-oxidized zigzag graphene
+nanoribbons. The oxidation schemes considered include hydroxyl, carboxyl,
+ether, and ketone groups. Using screened exchange density functional theory, we
+show that these oxidized ribbons are more stable than hydrogen-terminated
+nanoribbons except for the case of the etheric groups. The stable oxidized
+configurations maintain a spin-polarized ground state with antiferromagnetic
+ordering localized at the edges, similar to the fully hydrogenated
+counterparts. More important, edge oxidation is found to lower the onset
+electric field required to induce half-metallic behavior and extend the overall
+field range at which the systems remain half-metallic. Once the half-metallic
+state is reached, further increase of the external electric field intensity
+produces a rapid decrease in the spin magnetization up to a point where the
+magnetization is quenched completely. Finally, we find that oxygen containing
+edge groups have a minor effect on the energy difference between the
+antiferromagnetic ground state and the above-lying ferromagnetic state.",0704.2043v1
+2014-08-14,Emergent properties hidden in plane view: Strong electronic correlations at oxide interfaces,"Finding new collective electronic states in materials is one of the
+fundamental goals of condensed matter physics. Atomic-scale superlattices
+formed from transition metal oxides are a particularly appealing hunting ground
+for new physics. In bulk form, transition metal oxides exhibit a remarkable
+range of magnetic, superconducting, and multiferroic phases that are of great
+scientific interest and are potentially capable of providing innovative energy,
+security, electronics and medical technology platforms. In superlattices new
+states may emerge at the interfaces where dissimilar materials meet.
+  Here we illustrate the essential features that make transition metal
+oxide-based heterostructures an appealing discovery platform for emergent
+properties with a few selected examples, showing how charge redistributes,
+magnetism and orbital polarization arises and ferroelectric order emerges from
+heterostructures comprised of oxide components with nominally contradictory
+behavior with the aim providing insight into the creation and control of novel
+behavior at oxide interfaces by suitable mechanical, electrical or optical
+boundary conditions and excitations.",1408.3173v2
+2016-08-03,Moiré-free ultrathin iron oxide film: FeO(111) on Ag(111),"Ultrathin iron oxide films epitaxially grown on the (111)- and
+(0001)-oriented metal single crystal supports exhibit unique electronic,
+catalytic and magnetic properties not observed for the corresponding bulk
+oxides. These properties originate mainly from the presence of Moir\'e
+superstructures which, in turn, disqualify ultrathin films as model systems
+imitating bulk materials. We present a route for the preparation of a
+close-packed Moir\'e-free ultrathin iron oxide film, namely FeO(111) on
+Ag(111). Experimental scanning tunneling microscopy (STM), low energy electron
+diffraction (LEED) and x-ray photoelectron spectroscopy (XPS) results confirm
+perfect structural order in the film. Density functional theory (DFT)-based
+calculations suggest full relaxation of the oxide layer that adopts the atomic
+lattice of the crystalline support and exhibits properties similar to those of
+a free-standing FeO. The results open new pathways for model-type studies of
+electronic, catalytic and magnetic properties of fully-relaxed iron oxide films
+and related systems.",1608.01376v2
+2021-05-20,Magnetic avalanche of non-oxide conductive domain walls,"Atomically sharp domain walls (DWs) in ferroelectrics are considered as an
+ideal platform to realize easy-to-reconfigure nanoelectronic building blocks,
+created, manipulated and erased by external fields. However, conductive DWs
+have been exclusively observed in oxides, where DW mobility and conductivity is
+largely influenced by stoichiometry and defects. In contrast, we here report on
+conductive DWs in the non-oxide ferroelectric GaV$_4$S$_8$, where charge
+carriers are provided intrinsically by multivalent V$_4$ molecular clusters. We
+show that this new mechanism gives rise to DWs composed of nanoscale stripes
+with alternating electron and hole conduction, unimaginable in oxides. By
+exerting magnetic control on these segments we promote the mobile and
+effectively 2D DWs into dominating the 3D conductance, triggering abrupt
+conductance changes as large as eight orders of magnitude. The flexible
+valency, as origin of these novel hybrid DWs with giant conductivity,
+demonstrates that non-oxide ferroelectrics can be the source of novel phenomena
+beyond the realm of oxide electronics.",2105.09659v1
+2006-07-18,Dielectric breakdown in underoxidized magnetic tunnel junctions: Dependence on oxidation time and area,"Magnetic tunnel junctions (MTJs) with partially oxidized 9 \AA
+AlO$_x$-barriers were recently shown to have the necessary characteristics to
+be used as magnetoresistive sensors in high-density storage devices. Here we
+study dielectric breakdown in such underoxidized magnetic tunnel junctions,
+focusing on its dependence on tunnel junction area and oxidation time. A clear
+relation between breakdown mechanism and junction area is observed for the MTJs
+with the highest studied oxidation time: samples with large areas fail usually
+due to extrinsic causes (characterized by a smooth resistance decrease at
+dielectric breakdown). Small area junctions fail mainly through an intrinsic
+mechanism (sharp resistance decrease at breakdown). However, this dependence
+changes for lower oxidation times, with extrinsic breakdown becoming dominant.
+In fact, in the extremely underoxidized magnetic tunnel junctions, failure is
+exclusively related with extrinsic causes, independently of MTJ-area. These
+results are related with the presence of defects in the barrier (weak spots
+that lead to intrinsic breakdown) and of metallic unoxidized Al
+nanoconstrictions (leading to extrinsic breakdown).",0607452v1
+2011-02-10,"Hour-glass magnetic spectrum in an insulating, hole-doped antiferromagnet","Superconductivity in layered copper-oxide compounds emerges when charge
+carriers are added to antiferromagnetically-ordered CuO2 layers. The carriers
+destroy the antiferromagnetic order, but strong spin fluctuations persist
+throughout the superconducting phase and are intimately linked to
+super-conductivity. Neutron scattering measurements of spin fluctuations in
+hole-doped copper oxides have revealed an unusual `hour-glass' feature in the
+momentum-resolved magnetic spectrum, present in a wide range of superconducting
+and non-superconducting materials. There is no widely-accepted explanation for
+this feature. One possibility is that it derives from a pattern of alternating
+spin and charge stripes, an idea supported by measurements on stripe-ordered
+La1.875Ba0.125CuO4. However, many copper oxides without stripe order also
+exhibit an hour-glass spectrum$. Here we report the observation of an
+hour-glass magnetic spectrum in a hole-doped antiferromagnet from outside the
+family of superconducting copper oxides. Our system has stripe correlations and
+is an insulator, which means its magnetic dynamics can conclusively be ascribed
+to stripes. The results provide compelling evidence that the hour-glass
+spectrum in the copper-oxide superconductors arises from fluctuating stripes.",1102.2205v1
+2014-11-14,Electronic structure and magnetic properties of graphene/Co composites,"The results of measurements of XPS spectra and magnetic properties of
+graphene/Co composites prepared by adding of CoCl$_2$x6H$_2$O diluted in ethyl
+alcohol to highly-splitted graphite are presented. XPS Co 2p measurements show
+two sets of 2p$_{3/2,1/2}$-lines belonging to oxidized and metallic Co-atoms.
+This means that metal in composite is partly oxidized. This conclusion is
+confirmed by magnetic measurements which show the presence of the main (from
+the metal) and shifted (from the oxide) hysteresis loops. The presence of oxide
+layer on the metal surface prevents the metal from the full oxidation and (as
+shown by magnetic measurements) provides the preservation of ferromagnetic
+properties after long exposure in ambient air which enables the use of
+graphene/metal composites in spintronics devices.",1411.3863v1
+2022-05-23,Growth of delafossite CuAlO2 single crystals in a reactive crucible,"Delafossite oxide CuAlO2 has engaged great attention as a promising p-type
+conducting oxide. In this work, high-quality CuAlO2 single crystals with a size
+of several millimeters (mm) are successfully achieved with a reactive crucible
+melting method. The crystals are characterized by X-ray diffraction, scanning
+electron microscopy with energy-dispersive spectroscopy, transport measurement,
+and magnetic susceptibility measurement. The grown single crystals are free of
+contamination from a copper oxide flux. This work provides a new approach to
+growing high-quality delafossite oxide CuAlO2 with a few mm size.",2205.10979v1
+2008-09-11,Ferromagnetic ordering in dilute magnetic dielectrics with and without free carriers,"The state of art in the theoretical and experimental studies of transition
+metal doped oxides (dilute magnetic dielectrics) is reviewed. The available
+data show that the generic non-equilibrium state of oxide films doped with
+magnetic impurities may either favor ferromagnetism with high Curie temperature
+or result in highly inhomogeneous state without long-range magnetic order. In
+both case concomitant defects (vacancies, interstitial ions play crucial part.",0809.2005v1
+2014-12-30,Reversible control of Co magnetism by voltage induced oxidation,"We demonstrate that magnetic properties of ultra-thin Co films adjacent to
+Gd2O3 gate oxides can be directly manipulated by voltage. The Co films can be
+reversibly changed from an optimally-oxidized state with a strong perpendicular
+magnetic anisotropy to a metallic state with an in-plane magnetic anisotropy,
+or to an oxidized state with nearly zero magnetization, depending on the
+polarity and time duration of the applied electric fields. Consequently, an
+unprecedentedly large change of magnetic anisotropy energy up to 0.73 erg/cm2
+has been realized in a nonvolatile manner using gate voltages of only a few
+volts. These results open a new route to achieve ultra-low energy magnetization
+manipulation in spintronic devices.",1412.8668v1
+2006-02-18,Anomalous Flux Pinning in ?-Pyrochlore Oxide Superconductor KOs2O6,"The superconducting transition of the ?-pyrochlore oxide KOs2O6 with Tc =
+9.60 K is studied by resistivity measurements under various magnetic fields
+using a high-quality single crystal. The reentrant behavior of
+superconductivity is observed near Tc in low magnetic fields below 2 T. The
+recovered resistance probably due to flux flow exhibits an anomalous angle
+dependence, indicating that flux pinning is enhanced in magnetic fields along
+certain crystallographic directions such as [110], [001] and [112]. It is
+suggested that there is an intrinsic pinning mechanism coming from the specific
+crystal structure of the ?-pyrochlore oxide.",0602433v1
+2009-01-09,Magnetic structure of domain walls confined in a nano-oxide layer,"In the recent years, a spin-valve was developed with a current-confined-path
+structure consisting of a non-oxide-layer (NOL). We analyze magnetic structures
+of the current-confinedpath in the nano-oxide layer sandwiched between
+ferromagnetic electrodes and clarify the dependency of the magnetic structure
+on the shape and size of the current-confined-path. Our results of stiffness
+energy density and thermal stability shows that we should fabricate a CPP
+spin-valve with narrow current-confinedpaths with large aspect ratio and strong
+constriction in order to enhance the MR ratio.",0901.1189v1
+2009-06-23,Multiferroic oxides-based flash-memory and spin-field-effect transistor,"We propose a modified spin-field-effect transistor fabricated in a two
+dimensional electron gas (2DEG) formed at the surface of multiferroic oxides
+with a transverse helical magnetic order. The topology of the oxide local
+magnetic moments induces a resonant momentum-dependent effective spin-orbit
+interaction acting on 2DEG. We show that spin polarization dephasing is
+strongly suppressed which is crucial for functionality. The carrier spin
+precession phase depend linearly on the magnetic spiral helicity. The latter is
+electrically controllable by virtue of the magento-electric effect. We also
+suggest a flash-memory device based on this structure.",0906.4210v1
+2009-07-17,Electrically controlled persistent spin currents at the interface of multiferroic oxides,"We predict the appearance of a persistent spin current in a two-dimensional
+electron gas formed at the interface of multiferroic oxides with a transverse
+helical magnetic order. No charge current is generated. This is the result of
+an effective spin-orbit coupling generated by the topology of the oxide local
+magnetic moments. The effective coupling and the generated spin current depend
+linearly on the magnetic spiral helicity which, due to the magneto-electric
+coupling, is tunable by a transverse electric field offering thus a new mean
+for the generation of electrically controlled persistent spin currents.",0907.3023v1
+2017-12-15,"Tunable polymorphism of epitaxial iron oxides in the four-in-one ferroic-on-GaN system with magnetically ordered α-, γ-, ε-Fe2O3 and Fe3O4 layers","Hybridization of semiconducting and magnetic materials into a single
+heterostructure is believed to be potentially applicable to the design of novel
+functional spintronic devices. In the present work we report epitaxial
+stabilization of four magnetically ordered iron oxide phases (Fe3O4,
+{\gamma}-Fe2O3, {\alpha}-Fe2O3 and most exotic metastable {\epsilon}-Fe2O3) in
+the form of nanometer sized single crystalline films on GaN(0001) surface. The
+epitaxial growth of as many as four distinctly different iron oxide phases is
+demonstrated within the same single-target Laser MBE technological process on a
+GaN semiconductor substrate widely used for electronic device fabrication. The
+discussed iron oxides belong to a family of simple formula magnetic materials
+exhibiting a rich variety of outstanding physical properties including peculiar
+Verwey and Morin phase transitions in Fe3O4 and {\alpha}-Fe2O3 and multiferroic
+behavior in metastable magnetically hard {\epsilon}-Fe2O3 ferrite. The physical
+reasons standing behind the nucleation of a particular phase in an epitaxial
+growth process deserve interest from the fundamental point of view. The
+practical side of the presented study is to exploit the tunable polymorphism of
+iron oxides for creation of ferroic-on-semiconductor heterostructures usable in
+novel spintronic devices. By application of a wide range of experimental
+techniques the surface morphology, crystalline structure, electronic and
+magnetic properties of the single phase iron oxide epitaxial films on GaN have
+been studied. A comprehensive comparison has been made to the properties of the
+same ferrite materials in the bulk and nanostructured form reported by other
+research groups.",1712.05632v1
+2013-10-21,"Modifications in the frustrated magnetism, oxidation state of Co and magnetoelectric coupling effects induced by a partial replacement of Ca by Gd in the spin chain compound Ca3Co2O6","We have systematically investigated the influence of gradual replacement of
+Ca by Gd on the magnetic and complex dielectric properties of the well-known
+geometrically frustrated spin-chain system, Ca3Co2O6 (T_N= 24 K with additional
+magnetic transitions below 12K), by studying the series, Ca3-xGdxCo2O6 (x less
+than 0.7), down to 1.8K. Heat capacity measurements establish that the
+reduction of T_N with Gd substitution is much less as compared to that by Y
+substitution. The magnetic moment data reveal that there are changes in the
+oxidation state of Co as well, unlike for Y-substitution, beyond x= 0.2. Thus,
+despite being isovalent, both these substitutions interestingly differ in
+changing these magnetic properties in these oxides. We propose that the valence
+electrons of Y and those of R ions play different roles on deciding these
+magnetic characteristics of these mixed oxides. It is observed that a small
+amount (x= 0.3) of Gd substitution for Ca is enough to suppress glassy ac
+magnetic susceptibility behavior for the peak around 12 K. An additional
+low-temperature magnetic anomaly close to 5 K gets more prominent with
+increasing Gd concentration as revealed by heat-capacity data. Trends in
+temperature dependence of complex dielectric behavior were also tracked with
+varying composition and a frequency dependence is observed, not only for the
+transition in the region around 10 K (for some compositions), but also for the
+5 K transition which is well-resolved for a higher concentration of Gd. Thus,
+Gd-substituted Ca3Co2O6 series is shown to reveal interesting magnetic and
+dielectric behavior of this family of oxides.",1310.5635v1
+2002-08-21,Re-entrant spin glass and magnetoresistance in Co_{0.2}Zn_{0.8}Fe_{1.6}Ti_{0.4}O_4 spinel oxide,"We have investigated the static and dynamic response of magnetic clusters in
+Co_{0.2}Zn_{0.8}Fe_{1.6}Ti_{0.4}O_4 spinel oxide, where a sequence of magnetic
+phase transitions, i.e., paramagnetic (PM) to ferromagnetic at T_{C} $\leq$
+270K and ferromagnetic to canted spin glass state at T_f$ $\leq$ 125K is
+observed.",0208416v1
+2014-11-19,"Elastic, electronic and magnetic properties of new oxide perovskite BaVO3: a first-principles study","The structural, elastic, magnetic properties, as well as electronic structure
+and chemical bonding picture of new oxide 3d1-perovskite BaVO3, recently
+synthesized, were systematically investigated involving the first-principles
+FLAPW-GGA calculations. The obtained results are discussed in comparison with
+available experimental data, as well as with those obtained before for
+isostructural and isoelectronic SrVO3 perovskite.",1411.5128v1
+2013-02-15,A novel magnetic phase prior to a saturation moment in frustrated spinel oxides in ultra-high magnetic fields,"We have investigated the magnetic-field induced phases of a typical
+three-dimensional frustrated magnet, CdCr$_2$O$_4$, in magnetic fields of up to
+120 T that is generated by the single-turn coil techniques. We focused on
+magnetic phase transitions in proximity of a saturated magnetization moment. We
+utilized both the electromagnetic induction method using magnetic pick-up coils
+and magneto-optical spectroscopies of the $d$-$d$ transitions and the
+exciton-magnon-phonon transitions to study the magnetic properties subjected to
+ultra-high magnetic fields. Anomalies were observed in magneto-optical
+absorption intensity as well as differential magnetization prior to a fully
+polarized magnetic phase (a vacuum state in the magnon picture), revealing a
+novel magnetic phase associated with changes in both crystal and magnetic
+structures accompanied by the first order phase transition. Magnetic superfluid
+state such as an umbrella-like magnetic structure or a spin nematic state, is
+proposed as a candidate for the novel magnetic phase, which is found universal
+in the series of chromium spinel oxides, $A$Cr$_2$O$_4$ ($A$ = Zn, Cd, Hg).",1302.3664v1
+2021-11-20,Skyrmionics in correlated oxides,"While chiral magnets, metal-based magnetic multilayers, or Heusler compounds
+have been considered as the material workhorses in the field of skyrmionics,
+oxides are now emerging as promising alternatives, as they host special
+correlations between the spin-orbital-charge-lattice degrees of freedom and/or
+coupled ferroic order parameters. These interactions open new possibilities for
+practically exploiting skyrmionics. In this article, we review the recent
+advances in the observation and control of topological spin textures in various
+oxide systems. We start with the discovery of skyrmions and related
+quasiparticles in bulk and heterostructure ferromagnetic oxides. Next, we
+emphasize the shortcomings of implementing ferromagnetic textures, which have
+led to the recent explorations of ferrimagnetic and antiferromagnetic oxide
+counterparts, with higher Curie temperatures, stray-field immunity, low Gilbert
+damping, ultrafast magnetic dynamics, and/or absence of skyrmion deflection.
+Then, we highlight the development of novel pathways to control the stability,
+motion, and detection of topological textures using electric fields and
+currents. Finally, we present the outstanding challenges that need to be
+overcome to achieve all-electrical, nonvolatile, low-power oxide skyrmionic
+devices.",2111.10562v2
+2023-04-26,Assessment of sol-gel derived iron oxide substituted 45S5 bioglass-ceramics for biomedical applications,"Magnetic bioactive glass ceramic (MGC) powders have been synthesized by sol
+gel route by systematically substituting silicon dioxide with iron oxide in the
+45S5 glass composition. Powder x-ray diffraction studies revealed a variation
+in the percentage of combeite (Ca$_2$Na$_2$Si$_3$O$_9$), magnetite
+(Fe$_3$O$_4$), and hematite (Fe$_2$O$_3$) nanocrystalline phases in MGC powders
+as a function of composition. Zeta potential measurements showed that MGC
+containing up to 10 wt.% iron oxide formed stable suspensions. Saturation
+magnetization and heat generation capacity of MGC fluids increased with
+increase in iron oxide content. Degradation of MGC powders was investigated in
+phosphate buffer saline (PBS). In vitro bioactivity of the MGC powders taken in
+pellet form was confirmed by observing the pH variation as well as
+hydroxyapatite layer (HAp) formation upon soaking in modified simulated body
+fluid. These studies showed a decrement in overall bioactivity in samples with
+high iron oxide content due to the proportional decrease in silanol group.
+Monitoring the proliferation of MG-63 osteoblast cell in Dulbecco's Modified
+Eagle Medium (DMEM) revealed that MGC with up to 10 wt.% iron oxide exhibited
+acceptable viability. The systematic study revealed that the MGC with 10 wt.%
+iron oxide exhibited optimal cell viability, magnetic properties and induction
+heating capacity which were better than those of FluidMag-CT, which is used for
+hyperthermia treatment.",2304.13437v1
+2003-05-29,Magnetic Interactions in Transition-Metal Oxides,"This a review article, which presents a general framework for the analysis of
+interatomic magnetic interactions in the spin-density-functional theory, which
+is based on the magnetic force theorem, make a link with the models for
+transition-metal oxides, and gives several examples of how this strategy can be
+used for the analysis of magnetic properties of colossal-magnetoresistive
+perovskite manganites, double perovskite and pyrochlore compounds.",0305668v1
+2017-08-16,Copper Tellurium Oxides - A Playground for Magnetism,"A variety of copper tellurium oxide minerals are known, and many of them
+exhibit either unusual forms of magnetism, or potentially novel spin liquid
+behavior. Here, I review a number of the more interesting materials with a
+focus on their crystalline symmetry and, if known, the nature of their
+magnetism. Many of these exist (so far) in mineral form only, and most have yet
+to have their magnetic properties studied. This means a largely unexplored
+space of materials awaits our exploration.",1708.05100v1
+2019-09-19,Electronic ferroelectricity and magneto-electric effect in phase separated magnetic oxidesElectronic ferroelectricity and magneto-electric effect in phase separated magnetic oxides,"We consider phase separated states in magnetic oxides (MO) thin films. We
+show that these states have a non-zero electric polarization. Moreover, the
+polarization is intimately related to a spatial distribution of magnetization
+in the film. Polarized states with opposite polarization and opposite magnetic
+configuration are degenerate. An external electric field removes the degeneracy
+and allows to switch between the two states. So, one can control electric
+polarization and magnetic configuration of the phase separated MO thin film
+with the external electric field.",1909.09176v1
+2015-03-26,Quantitative analysis of magnetic spin and orbital moments from an oxidized iron (1 1 0) surface using electron magnetic circular dichroism,"Understanding the ramifications of reduced crystalline symmetry on magnetic
+behavior is a critical step in improving our understanding of nanoscale and
+interfacial magnetism. However, investigations of such effects are often
+controversial largely due to the challenges inherent in directly correlating
+nanoscale stoichiometry and structure to magnetic behavior. Here, we describe
+how to use Transmission Electron Microscope (TEM) to obtain Electron Magnetic
+Circular Dichroism (EMCD) signals as a function of scattering angle to locally
+probe the magnetic behavior of thin oxide layers grown on an Fe (1 1 0)
+surface. Experiments and simulations both reveal a strong dependence of the
+magnetic orbital to spin ratio on its scattering vector in reciprocal space. We
+exploit this variation to extract the magnetic properties of the oxide cladding
+layer, showing that it locally may exhibit an enhanced orbital to spin moment
+ratio. This finding is supported here by both spatially and angularly resolved
+EMCD measurements, opening up the way for compelling investigations into how
+magnetic properties are affected by nanoscale features.",1503.07681v2
+2007-07-21,Ferromagnetism as a universal feature of nanoparticles of the otherwise nonmagnetic oxides,"Room-temperature ferromagnetism has been observed in the nanoparticles (7 -
+30 nm dia) of nonmagnetic oxides such as CeO2, Al2O3, ZnO, In2O3 and SnO2. The
+saturated magnetic moments in CeO_2 and Al_2O_3 nanoparticles are comparable to
+those observed in transition metal doped wide band semiconducting oxides. The
+other oxide nanoparticles show somewhat lower values of magnetization but with
+a clear hysteretic behavior. Conversely, the bulk samples obtained by sintering
+the nanoparticles at high temperatures in air or oxygen became diamagnetic. As
+there were no magnetic impurities present, we assume that the origin of
+ferromagnetism may be due to the exchange interactions between localized
+electron spin moments resulting from oxygen vacancies at the surfaces of
+nanoparticles. We suggest that ferromagnetism may be a universal characteristic
+of nanopartilces of metal oxides",0707.3183v1
+1999-03-03,Mass enhancement of two-dimensional electrons in thin-oxide Si-MOSFET's,"We wish to report in this paper a study of the effective mass (m^*) in
+thin-oxide Si-metal-oxide-semiconductor field-effect-transistors, using the
+temperature dependence of the Shubnikov-de Haas (SdH) effect and following the
+methodology developed by J.L. Smith and P.J. Stiles, Phys. Rev. Lett. {\bf 29},
+102 (1972). We find that in the thin oxide limit, when the oxide thickness
+$d_{ox}$ is smaller than the average two-dimensional electron-electron
+separation r, m^* is still enhanced and the enhancement can be described by
+$m^*/m_B = 0.815 + 0.23(r/d_{ox})$, where $m_B = 0.195 m_e$ is the bulk
+electron mass, $m_e$ the free electron mass. At $n_s = 6 \times 10^{11}/cm^2$,
+for example, $m^* \simeq 0.25 m_e$, an enhancement doubles that previously
+reported by Smith and Stiles. Our result shows that the interaction between
+electrons in the semiconductor and the neutralizing positive charges on the
+metallic gate electrode is important for mass enhancement. We also studied the
+magnetic-field orientation dependence of the SdH effect and deduced a value of
+$3.0 \pm 0.5$ for the effective $g$ factor in our thin oxide samples.",9903058v1
+2001-11-14,Extrinsic Magnetotransport Phenomena in Ferromagnetic Oxides,"This review is focused on extrinsic magnetotransport effects in ferromagnetic
+oxides. It consists of two parts; the second part is devoted to an overview of
+experimental data and theoretical models for extrinsic magnetotransport
+phenomena. Here a critical discussion of domain-wall scattering is given.
+Results on surfacial and interfacial magnetism in oxides are presented.
+Spin-polarized tunnelling in ferromagnetic junctions is reviewed and
+grain-boundary magnetoresistance is interpreted within a model of
+spin-polarized tunnelling through natural oxide barriers. The situation in
+ferromagnetic oxides is compared with data and models for conventional
+ferromagnets. The first part of the review summarizes basic material
+properties, especially data on the spin-polarization and evidence for
+half-metallicity. Furthermore, intrinsic conduction mechanisms are discussed.
+An outlook on the further development of oxide spin-electronics concludes this
+review.",0111263v1
+2011-12-26,"Multiferroic and magnetoelectric nature of GaFeO3, AlFeO3 and related oxides","GaFeO3, AlFeO3 and related oxides are ferrimagnetic exhibiting
+magnetodielectric effect. There has been no evidence to date for
+ferroelectricity and hence multiferroicity in these oxides. We have
+investigated these oxides as well as oxides of the composition
+Al1-x-yGaxFe1+yO3 (x = 0.2, y = 0.2) for possible ferroelectricity by carrying
+out pyroelectric measurements. These measurements establish the occurrence of
+ferroelectricity at low temperatures below the N\`eel temperature in these
+oxides. They also exhibit significant magnetoelectric effect. We have tried to
+understand the origin of ferroelectricity based on non-centrosymmetric magnetic
+ordering and disorder by carrying out first-principles calculations.",1112.5848v2
+2023-12-27,Correlated Quantum Phenomena of Spin-Orbit Coupled Perovskite Oxide Heterostructures: Cases of SrRuO3 and SrIrO3-Based Artificial Superlattices,"Unexpected, yet useful functionalities emerge when two or more materials
+merge coherently. Artificial oxide superlattices realize atomic and crystal
+structures that are not available in nature, thus providing controllable
+correlated quantum phenomena. This review focuses on 4d and 5d oxide
+superlattices, in which the spin-orbit coupling plays a significant role
+compared with conventional 3d oxide superlattices. Modulations in crystal
+structures with octahedral distortion, phonon engineering, electronic
+structures, spin orderings, and dimensionality control are discussed for 4d
+oxide superlattices. Atomic and magnetic structures, Jeff = 1/2 pseudospin and
+charge fluctuations, and the integration of topology and correlation are
+discussed for 5d oxide superlattices. This review provides insights into how
+correlated quantum phenomena arise from the deliberate design of superlattice
+structures that give birth to novel functionalities.",2312.16748v1
+2008-06-18,Selective Heating Mechanism of Magnetic Metal Oxides by Alternating Magnetic Field in Microwave Sintering Process,"The mechanism of rapid and selective heating of magnetic metal oxides under
+the magnetic field of microwaves which continues beyond the Curie temperature $
+T_{c} $ is identified by using the Heisenberg model. Monte Carlo calculations
+based on the energy principle show that such heating is caused by non-resonant
+response of electron spins in the unfilled 3d shell to the wave magnetic field.
+Small spin reorientation thus generated leads to a large internal energy change
+through the exchange interactions between spins, which becomes maximal around $
+T_{c} $ for magnetite $ {\rm Fe}_{3}{\rm O}_{4} $. The dissipative spin
+dynamics simulation yields the imaginary part of the magnetic susceptibility,
+which becomes largest around $ T_{c} $ and for the microwave frequency around 2
+GHz. Hematite $ {\rm Fe}_{2}{\rm O}_{3} $ with weak spontaneous magnetization
+responds much less to microwaves as observed in experiments. The heating of
+titanium oxide by microwave magnetic field only when oxygen defects are present
+is also explained by our theory in terms of the absence of spontaneous
+magnetization.",0806.3055v3
+2020-12-10,Magnetic properties of poly(trimethylene terephthalate-block-poly(tetramethylene oxide) copolymer nanocomposites reinforced by graphene oxide-Fe3O4 hybrid nanoparticles,"Thermoplastic elastomeric nanocomposites based on poly(trimethylene
+terephthalate-block-poly(tetramethylene oxide) copolymer (PTT-PTMO) and
+graphene oxide-Fe3O4 nanoparticle hybrid were prepared by in situ
+polymerization. Superparamagnetic GO-Fe3O4 hybrid nanoparticles before
+introducing to elastomeric matrix were characterized by X-ray photoelectron
+spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TGA)
+and scanning electron microscopy (SEM). The effect of loading (0.3 and 0.5 wt%)
+of GO-Fe3O4 nanoparticle hybrid on the phase structure, tensile and magnetic
+properties of synthesized nanocomposites was investigated. The phase structure
+of nanocomposites was evaluated by differential scanning calorimetry (DSC) and
+dynamic mechanical thermal analysis (DMTA). Dispersion of GO-Fe3O4
+nanoparticles in elastomeric matrix was evaluated by transmission electron
+microscopy (TEM). Magnetic properties of GO-Fe3O4 nanoparticle hybrid and
+nanocomposites with their content were characterized by using two different
+techniques: dc SQUID magnetization measurements as a function of temperature
+(from 2 to 300 K) and external magnetic field and ferromagnetic resonance (FMR)
+at microwave frequency.",2012.05819v1
+1997-04-28,Reproducible magnetic fluctuations of microwave absorption in zeolites,"For polycrystalline specimens of zeolites treated to thermal oxidation we
+have revealed and studied the weak spectra of reproducible magnetic microwave
+absorption fluctuations at a frequency of 9.4 GHz. The investigation was
+carried out by the ESR method over the 77-500 K temperature range. The
+fluctuation spectra have features typical of mesoscopic phenomena observed
+previously in ESR spectra of high temperature superconductors and metals at
+temperatures below critical. The similar fluctuation spectra were obtained at
+300 K for some oxides, oxidized silver and gold particles. The experiments
+performed are, perhaps, the first observation of the phenomenon at unusually
+high temperatures which has been observed only in superconducting systems.",9704230v1
+2013-06-08,Effect of Spin-Orbit Interaction on (4d)^3- and (5d)^3 -Based Transition-Metal Oxides,"The effects of a spin-orbit interaction on transition-metal ions of (4d)^3-
+and (5d)^3 -based oxides in which three electrons occupy t_{2g} orbitals are
+studied. The amplitude of the magnetic moment of d electrons on the 5d and 4d
+orbitals is estimated by numerical diagonalization. It is found that the
+magnetic moment is reduced by the spin-orbit interaction. It is suggested that
+(4d)^3- and (5d)^3 -based oxides are located in the middle of the L-S and J-J
+coupling schemes.",1306.1880v1
+2019-12-08,Thermal Conductivity of Oxide Tunnel Barriers in Magnetic Tunnel Junctions Measured by Ultrafast Thermoreflectance and Magneto-optic Kerr Effect Thermometry,"Spin-dependent charge transport in magnetic tunnel junctions (MTJs) can be
+manipulated by a temperature gradient, which can be utilized for spintronic and
+spin caloritronic applications. Evaluation of the thermally induced phenomena
+requires knowledge of the temperature differences across the oxide tunnel
+barrier adjacent to the ferromagnetic (FM) leads. However, it is challenging to
+accurately measure thermal properties of an oxide tunnel barrier consisting of
+only a few atomic layers. In this work, we experimentally interrogate the
+temperature evolutions in Ru/oxide/FM/seed/MgO (oxide=MgO, MgAl2O4; FM=Co,
+CoFeB; seed=Pt, Ta) structures having perpendicular magnetic anisotropy using
+ultrafast thermometry. The Ru layer is optically thick and heated by ultrafast
+laser pulses; the subsequent temperature changes are monitored using
+thermoreflectance of Ru and magneto-optic Kerr effect (MOKE) of the FM layers.
+We independently measure the response times of Co and CoFeB magnetism using
+quadratic MOKE and obtain {\tau}em=0.2 ps for Co and 2 ps for CoFeB. These time
+scales are much shorter than the time scale of heat transport through the oxide
+tunnel barrier, which occurs at 10-3000 ps. We determine effective thermal
+conductivities of MgO and MgAl2O4 tunnel barriers in the range of 0.4-0.6 W m-1
+K-1, comparable to an estimate of the series conductance of the Ru/oxide and
+oxide/FM interfaces and an order of magnitude smaller than the thermal
+conductivity of MgO thin films. We find that the electron-phonon thermal
+conductance near the tunnel barrier is only a factor of 5-12 larger than the
+thermal conductance of the oxide tunnel barrier. Therefore, the drop in the
+electronic temperature is approximately 20-30% larger than the drop in the
+phonon temperature across the tunnel barrier.",1912.03588v1
+2021-08-25,Kinetics of ion migration in the electric field-driven manipulation of magnetic anisotropy of Pt/Co/oxide multilayers,"Magneto-ionics, by which the magnetic properties of a thin layer can be
+modified through the migration of ions within a liquid or solid electrolyte, is
+a fast developing research field. This is mainly due to the perspective of
+energy efficient magnetic devices, in which the magnetization direction is
+controlled not by a magnetic field or an electrical current, as done in
+traditional devices, but by an electric field, leading to a considerable
+reduction of energy consumption.
+  In this work, the interfacial perpendicular magnetic anisotropy (PMA) of a
+series of Pt/Co/oxide trilayers covered by a ZrO$_2$ layer, acting as a ionic
+conductor, was finely tuned by a gate voltage at room temperature. The
+non-volatility and the time evolution of the effect point at oxygen ion
+migration across the ZrO$_2$ layer as the driving mechanism. A large variation
+of the PMA is obtained by modifying the degree of oxidation of the cobalt layer
+with the flux of oxygen ions: the easy magnetization axis can be switched
+reversibly from in-plane, with an under-oxidized Co, to in-plane, with an
+over-oxidized Co, passing through an out-of-plane magnetization with maximum
+PMA. The switching time between the different magnetic states is limited by the
+oxygen ion drift velocity through the multilayer structure. This was shown to
+depend exponentially on the applied bias voltage, and could be varied by over 5
+orders of magnitude, from several minutes to a few ms. On the other hand, for a
+fixed gate-voltage, the oxidation of the cobalt layer decreases exponentially
+as a function of time. This behavior is in agreement with the theoretical model
+developed by Cabrera and Mott (1949) to explain the growth of very thin oxides
+at low temperatures. The possibility to explain the observed effect with a
+relatively simple theoretical model opens the possibility to engineers
+materials with optimized properties.",2108.11263v1
+2005-09-22,Magnetism and half-metallicity at the O surfaces of ceramic oxides,"The occurence of spin-polarization at ZrO$_{2}$, Al$_{2}$O$_{3}$ and MgO
+surfaces is proved by means of \textit{ab-initio} calculations within the
+density functional theory. Large spin moments, as high as 1.56 $\mu_B$, develop
+at O-ended polar terminations, transforming the non-magnetic insulator into a
+half-metal. The magnetic moments mainly reside in the surface oxygen atoms and
+their origin is related to the existence of $2p$ holes of well-defined spin
+polarization at the valence band of the ionic oxide. The direct relation
+between magnetization and local loss of donor charge makes possible to extend
+the magnetization mechanism beyond surface properties.",0509578v1
+2006-02-07,Angular dependence of the magnetic-field driven superconductor-insulator transition in thin films of amorphous indium-oxide,"A significant anisotropy of the magnetic-field driven
+superconductor-insulator transition is observed in thin films of amorphous
+indium-oxide. The anisotropy is largest for more disordered films which have a
+lower transition field. At higher magnetic field the anisotropy reduces and
+even changes sign beyond a sample specific and temperature independent magnetic
+field value. The data are consistent with the existence of more that one
+mechanism affecting transport at high magnetic fields.",0602160v1
+2009-02-19,Is the nature of magnetic order in copper-oxides and in iron-pnictides different?,"We use the results of first-principles electronic structure calculations and
+a strong coupling perturbation approach, together with general theoretical
+arguments, to illustrate the differences in super-exchange interactions between
+the copper-oxides and iron-pnictides. We show that the two magnetic ground
+states can be understood in a simple manner within the same theoretical
+foundation. Contrary to the emerging view that magnetic order in the
+iron-pnictides is of itinerant nature, we argue that the observed magnetic
+moment is small because of frustration introduced by the electrons of the Fe
+orbitals as they compete to impose their preferred magnetic ordering.",0902.3450v1
+2014-09-15,Ferroelectric Control of Magnetism and Transport in Oxide Heterostructures,"Magnetism and transport are two key functional ingredients in modern
+electronic devices. In oxide heterostructures, ferroelectricity can provide a
+new route to control these two properties via electrical operations, which is
+scientifically interesting and technologically important. In this Brief Review,
+we will introduce recent progresses on this fast developing research field.
+Several subtopics will be covered. First, the ferroelectric polarization tuning
+of interfacial magnetism will be introduced, which includes the tuning of
+magnetization, easy axis, magnetic phases, as well as exchange bias. Second,
+the ferroelectric polarization tuning of transverse and tunneling transport
+will be reviewed.",1409.4125v1
+2016-06-09,Nanocomposite RE-Ba-Cu-O bulk superconductors,"Nanocomposite oxide high-temperature bulk superconductors can be used as
+quasi-magnets. Thanks to the recent progress of material processing,
+quasi-magnet with 26 mm diameter can generate a large field of 17.6 T at 26 K.
+These results are highly attractive for applications, involving levitation of
+permanent magnets on the bulk superconductors. Indeed, several other
+applications such as motors and magnetic resonance microscope using bulk
+superconductors have been proposed and demonstrated. In this chapter, we
+describe several techniques to improve the magnetic properties for bulk
+superconductors together with some basics such as phase diagrams and
+solidifications.",1606.02872v1
+2019-11-15,Cation spin and superexchange interaction in oxide materials below and above spin crossover under high pressure,"We derived simple rules for the sign of superexchange interaction based on
+the multielectron calculations of the superexchange interaction in the
+transition metal oxides that are valid both below and above spin crossover
+under high pressure. The superexchange interaction between two cations in d$^n$
+configurations is given by a sum of individual contributions related to the
+electron-hole virtual excitations to the different states of the d$^{n + 1}$
+and d$^{n - 1}$ configurations. Using these rules, we have analyzed the sign of
+the superexchange interaction of a number of oxides with magnetic cations in
+electron configurations from d$^2$ till d$^8$: the iron, cobalt, chromium,
+nickel, copper and manganese oxides with increasing pressure. The most
+interesting result concerns the magnetic state of cobalt and nickel oxides CoO,
+Ni$_2$O$_3$ and also La$_2$CoO$_4$, LaNiO$_3$ isostructural to well-known
+high-T$_C$ and colossal magnetoresistance materials. These oxides have a spin
+$\frac{1}{2}$ at the high pressure. Change of the interaction from
+antiferromagnetic below spin crossover to ferromagnetic above spin crossover is
+predicted for oxide materials with cations in d$^5$(FeBO$_3$) and d$^7$(CoO)
+configurations, while for materials with the other d$^n$ configurations spin
+crossover under high pressure does not change the sign of the superexchange
+interaction.",1911.06482v3
+2001-06-26,Superconductivity in a pyrochlore oxide Cd2Re2O7,"We make the first report that a metallic pyrochlore oxide \Cd2Re2O7, exhibits
+type II superconductivity at 1.1 K. The pyrochlore oxide is known to be a
+geometrical frustrated system, which includes the tetrahedral network of
+magnetic ions. A large number of compounds are classified in the family of
+pyrochlore oxides, and these compounds exhibit a wide variety of physical
+properties ranging from insulator through semiconductor and from bad metal to
+good metal. Until now, however, no superconductivity has been reported for
+frustrated pyrochlore oxides. The bulk superconductivity of this compound is
+confirmed by measurements of the resistivity and the a. c. magnetic
+susceptibility. The \Hc2, which is extrapolated to 0 K, is estimated as about
+0.8 T, using the resistivity measurements under aplied field. The plot of \Hc2
+vs $T$ indicates that the Cooper pairs are composed of rather heavy
+quasiparticles. This fact suggests that frustrated heavy electrons become
+superconducting in this compound.",0106521v1
+2002-08-24,"Crystal structure, electronic, and magnetic properties of the bilayered rhodium oxide Sr3Rh2O7","The bilayered rhodium oxide Sr3Rh2O7 was synthesized by high-pressure and
+high-temperature heating techniques. The single-phase polycrystalline sample of
+Sr3Rh2O7 was characterized by measurements of magnetic susceptibility,
+electrical resistivity, specific heat, and thermopower. The structural
+characteristics were investigated by powder neutron diffraction study. The
+rhodium oxide Sr3Rh2O7 [Bbcb, a = 5.4744(8) A, b = 5.4716(9) A, c = 20.875(2)
+A] is isostructural to the metamagnetic metal Sr3Ru2O7, with five 4d electrons
+per Rh, which is electronically equivalent to the hypothetic bilayered
+ruthenium oxide, where one electron per Ru is doped into the Ru-327 unit. The
+present data show the rhodium oxide Sr3Rh2O7 to be metallic with enhanced
+paramagnetism, similar to Sr3Ru2O7. However, neither manifest contributions
+from spin fluctuations nor any traces of a metamagnetic transition were found
+within the studied range from 2 K to 390 K below 70 kOe.",0208467v1
+2005-07-18,Anomalous magnetoresistance behavior of CoFe nano-oxide spin valves at low temperatures,"We report magnetoresistance curves of CoFe nano-oxide specular spin valves of
+MnIr/CoFe/nano-oxidized CoFe/CoFe/Cu/CoFe/nano-oxidized CoFe/Ta at different
+temperatures from 300 to 20 K. We extend the Stoner-Wolfarth model of a common
+spin valve to a specular spin valve, introducing the separation of the pinned
+layer into two sublayers and their magnetic coupling across the nano-oxide. We
+study the effect of different coupling/exchange (between the antiferromagnetic
+layer and the bottom sublayer) field ratios on the magnetization and
+magnetoresistance, corresponding with the experimentally observed anomalous
+bumps in low temperature magnetoresistance curves.",0507423v1
+2010-08-09,Detection of bottom ferromagnetic electrode oxidation in magnetic tunnel junctions by magnetometry measurements,"Surface oxidation of the bottom ferromagnetic (FM) electrode, one of the
+major detrimental factors to the performance of a Magnetic Tunnel Junction
+(MTJ), is difficult to avoid during the fabrication process of the MTJ's tunnel
+barrier. Since Co rich alloys are commonly used for the FM electrodes in MTJs,
+over-oxidation of the tunnel barrier results in the formation of a CoO
+antiferromagnetic (AF) interface layer which couples with the bottom FM
+electrode to form a typical AF/FM exchange bias (EB) system. In this work,
+surface oxidation of the CoFe and CoFeB bottom electrodes was detected via
+magnetometry measurements of exchange-bias characterizations including the EB
+field, training effect, uncompensated spin density, and coercivity. Variations
+of these parameters were found to be related to the surface oxidation of the
+bottom electrode, among them the change of coercivity is most sensitive.
+Annealed samples show evidence for an oxygen migration back to the MgO tunnel
+barrier by annealing.",1008.1493v1
+2019-01-03,Origin of band gaps in 3d perovskite oxides,"With their broad range of magnetic, electronic and structural properties,
+transition metal perovskite oxides ABO3 have long served as a platform for
+testing condensed matter theories. In particular, their insulating character -
+found in most compounds - is often ascribed to dynamical electronic
+correlations through the celebrated Mott-Hubbard mechanism where gaping arises
+from a uniform, symmetry-preserving electron repulsion mechanism. However,
+structural distortions are ubiquitous in perovskites and their relevance with
+respect to dynamical correlations in producing this rich array of properties
+remains an open question. Here, we address the origin of band gap opening in
+the whole family of 3d perovskite oxides. We show that a single-determinant
+mean-field approach such as density functional theory (DFT) successfully
+describes the structural, magnetic and electronic properties of the whole
+series, at low and high temperatures. We find that insulation occurs via
+energy-lowering crystal symmetry reduction (octahedral rotations, Jahn-Teller
+and bond disproportionation effects), as well as intrinsic electronic
+instabilities, all lifting orbital degeneracies. Our work therefore suggests
+that whereas ABO3 oxides may be complicated, they are not necessarily strongly
+correlated. It also opens the way towards systematic investigations of doping
+and defect physics in perovskites, essential for the full realization of
+oxide-based electronics.",1901.00829v1
+2023-01-10,Anionic nickel and nitrogen effects in the chiral antiferromagnetic antiperovskite Mn$_3$NiN,"Magnetic antiperovskites, holding chiral noncollinear antiferromagnetic
+ordering, have shown remarkable properties that cover from negative thermal
+expansion to anomalous Hall effect. Nevertheless, details on the electronic
+structure related to the oxidation states and the octahedral center's site
+effect are still scarce. Here, we show a theoretical study, based on
+first-principles calculations in the framework of the density-functional
+theory, DFT, on the electronic details associated with the nitrogen site effect
+into the structural, electronic, magnetic, and topological degrees of freedom.
+Thus, we show that the nitrogen-vacancy increases the values of the anomalous
+Hall conductivity and retains the chiral $\Gamma_{4g}$ antiferromagnetic
+ordering. Moreover, we reveal, based on the Bader charges and the electronic
+structure analysis, the negative and positive oxidation states in the Ni and Mn
+sites, respectively. The latter is in agreement with the expected
+$A_3^{\alpha+}B^{\beta-}X^{\delta-}$ oxidation states to satisfy the charge
+neutrality in the antiperovskites, but rare for transition metals. Finally, we
+extrapolate our findings on the oxidation states to several Mn$_3B$N compounds
+showing that the antiperovskite structure is an ideal platform to encounter
+negative oxidation states in metals sitting at the corner $B$-site.",2301.04242v1
+2017-12-18,Magnetic and universal magnetocaloric behavior of rare-earth substituted DyFe0.5Cr0.5O3,"We report the effect of partial substitution of Dy-site by rare-earths (R=Gd,
+Er and La)on the magnetic and magnetocaloric behavior of a mixed metal oxide
+DyFe0.5Cr0.5O3.Structural studies reveal that substitution of Dy by R has a
+minimal influence on the crystal structure. Magnetic and heat capacity studies
+show that the magnetic transition around 121 K observed for DyFe0.5Cr0.5O3
+remains unchanged with rare-earth substitution, whereas the lower magnetic
+transition temperature is suppressed/enhanced by magnetic/non-magnetic
+substitution. In all these compounds, the second order nature of magnetic
+transition is confirmed by Arrott plots. As compared to DyFe0.5Cr0.5O3, the
+values of magnetic entropy change and relative cooling power are increased with
+magnetic rare-earth substitution while it decreases with non-magnetic
+rare-earth substitution. In all these compounds, magnetic entropy change
+follows the power law dependence of magnetic field and the value of the
+exponent n indicate the presence of ferromagnetic correlation in an
+antiferromagnetic state. A phenomenological universal master curve is also
+constructed for all the compounds by normalizing the entropy change with
+rescaled temperature using a single reference temperature. This master curve
+also reiterates the second order nature of the magnetic phase transition in
+such mixed metal oxides.",1712.06396v1
+2019-01-17,"Influences of interfacial oxidization on surface magnetic energy, magnetic damping and spin-orbit-torques in Pt / ferromagnet / capping structures","We investigate the effect of capping layer (CAP) on the interfacial magnetic
+anisotropy energy density (K_S), magnetic damping ({\alpha}), and spin-orbit
+torques (SOTs) in heavy-metal (Pt) / ferromagnet (Co or Py) / CAP (MgO/Ta,
+HfOx, or TaN). At room temperature (RT) the CAP materials influence the
+effective magnitude of K_S, which is associated with a formation of interfacial
+magnetic oxides. The dynamical dissipation parameters of Co are considerably
+influenced by the CAP (especially MgO) while those of Py are not. This is
+possibly due to an extra magnetic damping via spin-pumping process across the
+Co/CoO interface and incoherent magnon generation (spin fluctuation) in the
+interfacial CoO. It is also observed that both anti-damping and field-like SOT
+efficiencies vary marginally with the CAP in the thickness ranges we examined.
+Our results reveal the crucial role of interfacial oxides on the perpendicular
+magnetic anisotropy, magnetic damping, and SOTs.",1901.05777v1
+2021-09-29,Magnetic interlayer coupling between ferromagnetic SrRuO$_3$ layers through a SrIrO$_3$ spacer,"A key element to tailor the properties of magnetic multilayers is the
+coupling between the individual magnetic layers. In case of skyrmion hosting
+multilayers, coupling of skyrmions across the magnetic layers is highly
+desirable. Here the magnetic interlayer coupling was studied in epitaxial
+all-oxide heterostructures of ferromagnetic perovskite SrRuO$_3$ layers
+separated by spacers of the strong spin-orbit coupling oxide SrIrO$_3$. This
+combination of oxide layers is being discussed as a potential candidate system
+to host N\'{e}el skyrmions. First order reversal curve (FORC) measurements were
+performed in order to distinguish between magnetic switching processes of the
+individual layers and to disentangle the signal of soft magnetic impurities
+from the samples$'$ signal. Additionally, FORC investigations enabled to
+determine whether the coupling between the magnetic layers is ferromagnetic or
+antiferromagnetic. The observed interlayer coupling strength was weak for all
+the heterostructures, with SrIrO$_3$ spacers between 2 monolayers and 12
+monolayers thick.",2109.14292v2
+2016-11-22,Exchange interactions in transition metal oxides: The role of oxygen spin polarization,"Magnetism of transition metal (TM) oxides is usually described in terms of
+the Heisenberg model, with orientation-independent interactions between the
+spins. However, the applicability of such a model is not fully justified for TM
+oxides because spin polarization of oxygen is usually ignored. In the
+conventional model based on the Anderson principle, oxygen effects are
+considered as a property of the TM ion and only TM interactions are relevant.
+Here, we perform a systematic comparison between two approaches for spin
+polarization on oxygen in typical TM oxides. To this end, we calculate the
+exchange interactions in NiO, MnO, and hematite (Fe2O3) for different magnetic
+configurations using the magnetic force theorem. We consider the full spin
+Hamiltonian including oxygen sites, and also derive an effective model where
+the spin polarization on oxygen renormalizes the exchange interactions between
+TM sites. Surprisingly, the exchange interactions in NiO depend on the magnetic
+state if spin polarization on oxygen is neglected, resulting in non-Heisenberg
+behavior. In contrast, the inclusion of spin polarization in NiO makes the
+Heisenberg model more applicable. Just the opposite, MnO behaves as a
+Heisenberg magnet when oxygen spin polarization is neglected, but shows strong
+non-Heisenberg effects when spin polarization on oxygen is included. In
+hematite, both models result in non-Heisenberg behavior. General applicability
+of the magnetic force theorem as well as the Heisenberg model to TM oxides is
+discussed.",1611.07288v2
+2004-01-31,Unprecedented Superconductivity in the beta-Pyrochlore Osmate KOs2O6,"Superconductivity in the potassium osmium oxide KOs2O6 crystallizing in the
+beta-pyrochlore structure is studied by means of electrical resistivity,
+magnetic susceptibility and specific heat. It is the second superconductor in
+the family of pyrochlore oxides, following the alfa-type pyrochlore oxide
+Cd2Re2O7 which is believed to be a conventional s-wave superconductor. The
+superconducting transition temperature Tc of KOs2O6 is 9.6 K, almost one order
+higher than the Tc = 1.0 K of Cd2Re2O7. Moreover, the superconductivity of
+KOs2O6 is remarkably robust under high magnetic fields, with a large upper
+critical magnetic field Hc2 of about 38 T, which seems to exceed Pauli's limit
+expected for conventional superconductivity. This is also in contrast to the
+case of Cd2Re2O7, in which the Hc2 is 0.29 T, much smaller than the
+corresponding Pauli's limit. These distinct contrasts strongly suggest that the
+mechanism of superconductivity is essentially different between the two
+pyrochlore oxides.",0402006v3
+2012-06-12,Electric field control of magnetic exchange coupling,"Electric control of magnetism is a vision which drives intense research on
+magnetic semiconductors and multiferroics. Recently, also ultrathin metallic
+films were reported to show magnetoelectric effects at room temperature. Here
+we demonstrate much stronger effects by exploiting reduction/oxidation
+reactions in a naturally grown oxide layer exchange coupled to an underlying
+ferromagnet. For the exemplarily studied FePt/iron oxide composite in an
+electrolyte, a large and reversible change of magnetization and anisotropy is
+obtained. The principle can be transferred to various metal/oxide combinations.
+It represents a novel approach towards multifunctionality.",1206.2467v3
+2011-11-25,Growth and electronic and magnetic structure of iron oxide films on Pt(111),"Ultrathin (111)-oriented polar iron oxide films were grown on a Pt(111)
+single crystal either by the reactive deposition of iron or oxidation of
+metallic iron monolayers. These films were characterized using low energy
+electron diffraction, scanning tunneling microscopy and conversion electron
+Mossbauer spectroscopy. The reactive deposition of Fe led to the island growth
+of Fe3O4, in which the electronic and magnetic properties of the bulk material
+were modulated by superparamagnetic size effects for thicknesses below 2 nm,
+revealing specific surface and interface features. In contrast, the oxide films
+with FeO stoichiometry, which could be stabilized as thick as 4 nm under
+special preparation conditions, had electronic and magnetic properties that
+were very different from their bulk counterpart, w\""ustite. Unusual long range
+magnetic order appeared at room temperature for thicknesses between three and
+ten monolayers, the appearance of which requires severe structural modification
+from the rock-salt structure.",1111.5938v2
+2014-06-18,Topological phases in Iridium oxide superlattices: quantized anomalous charge or valley Hall insulators,"We study topological phases in Iridium (Ir) oxide superlattices of
+orthorhombic perovskite-type grown along the [001] crystallographic axis. Due
+to strong spin-orbit coupling of Ir 5d-orbitals and electronic correlation
+effects, Ir oxide bilayer superlattices display topological magnetic insulators
+exhibiting quantized anomalous Hall effects. Depending on stacking of two
+layers, we also found a valley Hall insulator with counter-propagating edge
+currents from two different valleys and a topological crystalline insulator
+with edge states protected by the crystal lattice symmetry. In a single layer
+Ir oxide superlattice, a topological insulator can be achieved, when a strain
+field is applied to break the symmetry of a glide plane protecting the Dirac
+points. In the presence of a magnetic ordering or in-plane magnetic field, it
+turns into a topological magnetic insulator. We discuss essential ingredients
+for these topological phases and experimental signatures to test our
+theoretical proposals.",1406.4884v2
+2019-02-06,Iron oxide nanoparticles for magnetic hyperthermia,"Assemblies of magnetic nanoparticles show a great potential for application
+in biomedicine, in particular, in magnetic hyperthermia. However, to achieve
+desired therapeutic effect in magnetic hyperthermia the assembly of
+nanoparticles should have a sufficiently high specific absorption rate in
+alternating magnetic field of moderate amplitude and frequency.",1902.02220v1
+2020-06-25,Perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya interaction at an oxide/ferromagnetic metal interface,"We report on the study of both perpendicular magnetic anisotropy (PMA) and
+Dzyaloshinskii-Moriya interaction (DMI) at an oxide/ferromagnetic metal (FM)
+interface, i.e. BaTiO3 (BTO)/CoFeB. Thanks to the functional properties of the
+BTO film and the capability to precisely control its growth, we are able to
+distinguish the dominant role of the oxide termination (TiO2 vs BaO), from the
+moderate effect of ferroelectric polarization in the BTO film, on the PMA and
+DMI at the oxide/FM interface. We find that the interfacial magnetic anisotropy
+energy of the BaO-BTO/CoFeB structure is two times larger than that of the
+TiO2-BTO/CoFeB, while the DMI of the TiO2-BTO/CoFeB interface is larger. We
+explain the observed phenomena by first-principles calculations, which ascribe
+them to the different electronic states around the Fermi level at the
+oxide/ferromagnetic metal interfaces and the different spin-flip processes.
+This study paves the way for further investigation of the PMA and DMI at
+various oxide/FM structures and thus their applications in the promising field
+of energy-efficient devices.",2006.14268v1
+2023-01-02,Performance of the r$^{2}$SCAN functional in transition metal oxides,"We assess the accuracy and computational efficiency of the recently developed
+meta-generalized gradient approximation (metaGGA) functional, the restored
+regularized strongly constrained and appropriately normed (r$^2$SCAN), in
+transition metal oxide (TMO) systems and compare its performance against SCAN.
+Specifically, we benchmark the r$^2$SCAN-calculated oxidation enthalpies,
+lattice parameters, on-site magnetic moments, and band gaps of binary
+3\textit{d} TMOs against the SCAN-calculated and experimental values.
+Additionally, we evaluate the optimal Hubbard \emph{U} correction required for
+each transition metal (TM) to improve the accuracy of the r$^2$SCAN functional,
+based on experimental oxidation enthalpies, and verify the transferability of
+the \emph{U} values by comparing against experimental properties on other
+TM-containing oxides. Notably, including the \textit{U}-correction to r$^2$SCAN
+increases the lattice parameters, on-site magnetic moments and band gaps of
+TMOs, apart from an improved description of the ground state electronic state
+in narrow band gap TMOs. The r$^2$SCAN and r$^2$SCAN+\textit{U} calculated
+oxidation enthalpies follow the qualitative trends of SCAN and SCAN+\emph{U},
+with r$^2$SCAN and r$^2$SCAN+\textit{U} predicting marginally larger lattice
+parameters, smaller magnetic moments, and lower band gaps compared to SCAN and
+SCAN+\textit{U}, respectively. We observe that the overall computational time
+(i.e., for all ionic+electronic steps) required for r$^2$SCAN(+\textit{U}) to
+be lower than SCAN(+\textit{U}). Thus, the r$^2$SCAN(+\textit{U}) framework can
+offer a reasonably accurate description of the ground state properties of TMOs
+with better computational efficiency than SCAN(+\textit{U}).",2301.00535v1
+1996-06-05,Hall Resistivity in Ferromagnetic Manganese-Oxide Compounds,"Temperature-dependence and magnetic field-dependence of the Hall effect and
+the magnetic property in manganese-oxide thin films are studied. The
+spontaneous magnetization and the Hall resistivity are obtained for a various
+of magnetic fields over all the temperature. It is shown that the Hall
+resistivity in small magnetic field is to exhibit maximum near the Curie point,
+and strong magnetic field moves the position of the Hall resistivity peak to
+much high temperature and suppresses the peak value. The change of the Hall
+resistance in strong magnetic field may be larger than that of the diagonal
+ones. The abnormal Hall resistivity in the ferromagnetic manganese-oxide
+thin-films is attributed to the spin-correlation fluctuation scattering.",9606030v1
+2007-03-01,Magnetic effects at the interface between nonmagnetic oxides,"The electronic reconstruction at the interface between two insulating oxides
+can give rise to a highly-conductive interface. In analogy to this remarkable
+interface-induced conductivity we show how, additionally, magnetism can be
+induced at the interface between the otherwise nonmagnetic insulating
+perovskites SrTiO3 and LaAlO3. A large negative magnetoresistance of the
+interface is found, together with a logarithmic temperature dependence of the
+sheet resistance. At low temperatures, the sheet resistance reveals magnetic
+hysteresis. Magnetic ordering is a key issue in solid-state science and its
+underlying mechanisms are still the subject of intense research. In particular,
+the interplay between localized magnetic moments and the spin of itinerant
+conduction electrons in a solid gives rise to intriguing many-body effects such
+as Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions, the Kondo effect, and
+carrier-induced ferromagnetism in diluted magnetic semiconductors. The
+conducting oxide interface now provides a versatile system to induce and
+manipulate magnetic moments in otherwise nonmagnetic materials.",0703028v2
+2013-07-21,Room-Temperature Electronically-Controlled Ferromagnetism at the LaAlO3/SrTiO3 Interface,"Reports of emergent conductivity, superconductivity, and magnetism at oxide
+interfaces have helped to fuel intense interest in their rich physics and
+technological potential. Here we employ magnetic force microscopy to search for
+room-temperature magnetism in the well-studied LaAlO3/SrTiO3 system. Using
+electrical top gating to deplete electrons from the oxide interface, we
+directly observe an in-plane ferromagnetic phase with sharply defined domain
+walls. Itinerant electrons, introduced by a top gate, align
+antiferromagnetically with the magnetization, at first screening and then
+destabilizing it as the conductive state is reached. Subsequent depletion of
+electrons results in a new, uncorrelated magnetic pattern. This newfound
+control over emergent magnetism at the interface between two non-magnetic
+oxides portends a number of important technological applications.",1307.5557v2
+2014-01-09,Persistent Optically Induced Magnetism in Oxygen-Deficient Strontium Titanate,"Strontium titanate (SrTiO$_3$) is a foundational material in the emerging
+field of complex oxide electronics. While its electronic and optical properties
+have been studied for decades, SrTiO$_3$ has recently become a renewed
+materials research focus catalyzed in part by the discovery of magnetism and
+superconductivity at interfaces between SrTiO$_3$ and other oxides. The
+formation and distribution of oxygen vacancies may play an essential but
+as-yet-incompletely understood role in these effects. Moreover, recent
+signatures of magnetization in gated SrTiO$_3$ have further galvanized interest
+in the emergent properties of this nominally nonmagnetic material. Here we
+observe an optically induced and persistent magnetization in oxygen-deficient
+SrTiO$_{3-\delta}$ using magnetic circular dichroism (MCD) spectroscopy and
+SQUID magnetometry. This zero-field magnetization appears below ~18K, persists
+for hours below 10K, and is tunable via the polarization and wavelength of
+sub-bandgap (400-500nm) light. These effects occur only in oxygen-deficient
+samples, revealing the detailed interplay between magnetism, lattice defects,
+and light in an archetypal oxide material.",1401.1871v1
+2019-02-03,Long range antiferromagnetic order in a rocksalt high entropy oxide,"We report for the first time the magnetic structure of the high entropy oxide
+$(Mg_{0.2}Co_{0.2}Ni_{0.2}Cu_{0.2}Zn_{0.2})O$ using neutron powder diffraction.
+This material exhibits a sluggish magnetic transition but possesses a
+long-range ordered antiferromagnetic ground state, as revealed by DC and AC
+magnetic susceptibility, elastic and inelastic neutron scattering measurements.
+The magnetic propagation wavevector is k=(1/2, 1/2, 1/2) based on the cubic
+structure Fm-3m, and the magnetic structure consists of ferromagnetic sheets in
+the (111) planes with spins antiparallel between two neighboring planes.
+Inelastic neutron scattering reveals strong magnetic excitations at 100 K that
+survive up to room temperature. This work demonstrates that entropy-stabilized
+oxides represent a unique platform to study long range magnetic order with
+extreme chemical disorder.",1902.00833v1
+2019-02-05,Long-range magnetic ordering in rocksalt-type high-entropy oxides,"We report the magnetic properties of
+Mg$_{0.2}$Co$_{0.2}$Ni$_{0.2}$Cu$_{0.2}$Zn$_{0.2}$O, a high-entropy oxide with
+rocksalt structure, and the influence of substitutions on these properties.
+From the magnetic susceptibility and neutron diffraction measurements, we found
+that this compound exhibits long-range magnetic order below 120 K despite the
+substantial structuraldisorder. The other rocksalt-type high-entropy oxides
+with various chemical substitutions were found to host either an
+antiferromagnetic order or spin-glass state depending on the amount of magnetic
+ions. The presence of magnetic order for such a disordered material potentially
+provide a route to explore novel magnetic properties and functions.",1902.01825v2
+2020-08-20,Engineering the magnetic and magnetocaloric properties of PrVO3 epitaxial oxide thin films by strain effects,"Combining multiple degrees of freedom in strongly-correlated materials such
+as transition-metal oxides would lead to fascinating magnetic and
+magnetocaloric features. Herein, the strain effects are used to markedly tailor
+the magnetic and magnetocaloric properties of PrVO3 thin films. The selection
+of appropriate thickness and substrate enables us to dramatically decrease the
+coercive magnetic field from 2.4 T previously observed in sintered PVO3 bulk to
+0.05 T for compressive thin films making from the PrVO3 compound a nearly soft
+magnet. This is associated with a marked enhancement of the magnetic moment and
+the magnetocaloric effect that reach unusual maximum values of roughly 4.86 uB
+and 56.8 J/kg K in the magnetic field change of 6 T applied in the sample plane
+at the cryogenic temperature range (3 K), respectively. This work strongly
+suggests that taking advantage of different degrees of freedom and the
+exploitation of multiple instabilities in a nanoscale regime is a promising
+strategy for unveiling unexpected phases accompanied by a large magnetocaloric
+effect in oxides.",2008.09193v1
+2020-08-28,Tunnel magnetoresistance in scandium nitride magnetic tunnel junctions using first principles,"The magnetic tunnel junction is a cornerstone of spintronic devices and
+circuits, providing the main way to convert between magnetic and electrical
+information. In state-of-the-art magnetic tunnel junctions, magnesium oxide is
+used as the tunnel barrier between magnetic electrodes, providing a uniquely
+large tunnel magnetoresistance at room temperature. However, the wide bandgap
+and band alignment of magnesium oxide-iron systems increases the
+resistance-area product and causes challenges of device-to-device variability
+and tunnel barrier degradation under high current. Here, we study using first
+principles narrower-bandgap scandium nitride tunneling properties and transport
+in magnetic tunnel junctions in comparison to magnesium oxide. These
+simulations demonstrate a high tunnel magnetoresistance in Fe/ScN/Fe MTJs via
+{\Delta}_1 and {\Delta}_2' symmetry filtering with low wavefunction decay
+rates, allowing a low resistance-area product. The results show that scandium
+nitride could be a new tunnel barrier material for magnetic tunnel junction
+devices to overcome variability and current-injection challenges.",2008.12770v1
+2022-02-08,"Electronic, Magnetic and Vibrational Properties of Single Layer Aluminum Oxide","The structural, magnetic, vibrational and electronic properties of single
+layer aluminum oxide (AlO2) are investigated by performing state-of-the-art
+first-principles calculations. Total energy optimization and phonon
+calculations reveal that aluminum oxide forms a distorted octahedral structure
+(1T'-AlO2) in its single layer limit. It is also shown that surfaces of
+1T'-AlO2 display magnetic behavior originating from the O atoms. While the
+ferromagnetic (FM) state is the most favorable magnetic order for 1T'-AlO2,
+transformation to a dynamically stable antiferromagnetic (AFM) state upon a
+slight distortion in the crystal structure is also possible. It is also shown
+that Raman activities (350-400 cm^-1) obtained from the vibrational spectrum
+can be utilized to distinguish the possible magnetic phases of the crystal
+structure. Electronically, both FM and the AFM phases are semiconductors with
+an indirect band gap and they can form a type-III vdW heterojunction with
+graphene-like ultra-thin materials. Moreover, it is predicted that presence of
+oxygen defects that inevitably occur during synthesis and production do not
+alter the magnetic state, even at high vacancy density. Apparently, ultra-thin
+1T'-AlO2 with its stable crystal structure, semiconducting nature and robust
+magnetic state is a quite promising material for nanoscale device applications.",2202.04144v1
+2023-04-01,Magnetic proximity effect at the interface of two-dimensional materials and magnetic oxide insulators,"Two-dimensional (2D) materials provide a platform for developing novel
+spintronic devices and circuits for low-power electronics. In particular,
+inducing magnetism and injecting spins in graphene have promised the emerging
+field of graphene spintronics. This review focuses on the magnetic proximity
+effect at the interface of 2D materials and magnetic oxide insulators. We
+highlight the unique spin-related phenomena arising from magnetic exchange
+interaction and spin-orbital coupling in 2D materials coupled with magnetic
+oxides. We also describe the fabrication of multifunctional hybrid devices
+based on spin transport. We conclude with a perspective of the field and
+highlight challenges for the design and fabrication of 2D spintronic devices
+and their potential applications in information storage and logic devices.",2304.00356v1
+2024-01-31,Tailoring magnetic and hyperthermia properties of biphase iron oxide nanocubes through post-annealing,"Tailoring the magnetic properties of iron oxide nanosystems is essential to
+expand their biomedical applications. In this study, the 34 nm iron oxide
+nanocubes with two phases consisting of Fe3O4 and alpha-Fe2O3 were annealed for
+2 hours in the presence of O2, N2, He, and Ar to tune the respective phase
+volume fractions and control the magnetic properties. X-ray diffraction and
+magnetic measurements were carried out post-treatment to evaluate the changes
+of the treated samples compared to the as-prepared, which showed an enhancement
+of the alpha-Fe2O3 phase in the samples annealed with O2, while the others
+indicated Fe3O4 enhancement. Furthermore, the latter samples indicated
+enhancements in the crystallinity and saturation magnetization while coercivity
+enhancement was most significant in the samples annealed with O2, resulting in
+the highest specific absorption rates (up to 1000 W/g) in all the applied
+fields of 800, 600, and 400 Oe in agar during magnetic hyperthermia
+measurements. The general enhancement in the specific absorption rate
+post-annealing underscores the importance of the annealing atmosphere in the
+enhancement of the magnetic and structural properties of nanostructures.",2401.18009v1
+2005-10-13,Erratum to Three Papers on the beta-Pyrochlore Oxide Superconductors,"The magnitude of magnetic fields given in the three papers that report on the
+superconductivity of the beta-pyrochlore oxides is corrected.",0510369v2
+2016-07-20,MegaOhm Extraordinary Hall effect in oxidized CoFeB,"We report on development of controllably oxidized CoFeB ferromagnetic films
+demonstrating the extraordinary Hall effect (EHE) resistivity exceeding 1 Ohmcm
+and magnetic field sensitivity up to 10^6 Ohm/T. Such EHE resistivity is four
+orders of magnitude higher than previously observed in ferromagnetic materials,
+while sensitivity is two orders larger than the best of semiconductors",1607.05923v1
+2012-05-14,Superconductivity in Mg/MgO interface,"Metastable superconductivity at \approx 50 K in the interfaces formed by
+metallic and oxidized magnesium (MgO) has been observed by ac magnetic
+susceptibility and electrical resistance measurements. The superconducting
+interfaces have been produced by the surface oxidation of metallic magnesium
+under special conditions.",1205.2981v1
+2017-04-25,Characterization of Zinc oxide & Aluminum Ferrite and Simulation studies of M-H plots of Cobalt/Cobaltoxide,"Zinc oxide and Aluminum Ferrite were prepared Chemical route. The samples
+were characterized by XRD and VSM. Simulation of M-H plots of Co/CoO thin films
+were performed. Effect of parameters was observed on saturation magnetization.",1705.00525v2
+2001-09-27,Enhanced paramagnetism of the 4d itinerant electrons in the rhodium oxide perovskite SrRhO3,"Polycrystalline rhodium(IV) oxide perovskite SrRhO3 was obtained by
+high-pressure synthesis techniques, followed by measurements of the magnetic
+susceptibility, electrical resistivity, and specific heat. The title compound
+has five 4d-electrons per perovskite unit and shows Fermi-liquid behavior in
+its electrical resistivity. The magnetic susceptibility is large [chi(300K)
+\~1.1*10^{-3} emu/mol-Rh] and proportional to 1/T^2 (< 380 K), while there is
+no magnetic long-range order above 1.8 K. The specific heat measurements
+indicate a probable magnetic contribution below ~ 15 K, which is not predicted
+by the self-consistent renormalization theory of spin fluctuations for both
+antiferro- and ferromagnetic 3D nearly-ordered metals.",0109522v2
+2007-11-02,Origin and control of ferromagnetism in dilute magnetic semiconductors and oxides,"The author reviews the present understanding of the hole-mediated
+ferromagnetism in magnetically doped semiconductors and oxides as well as the
+origin of high temperature ferromagnetism in materials containing no valence
+band holes. It is argued that in these systems spinodal decomposition into
+regions with a large and a small concentration of magnetic component takes
+place. This self-organized assembling of magnetic nanocrystals can be
+controlled by co-doping and growth conditions. Functionalities of these
+multicomponent systems are described together with prospects for their
+applications in spintronics, nanoelectronics, photonics, plasmonics, and
+thermoelectrics.",0711.0343v1
+2010-10-26,Giant directional dichroism of terahertz light in resonance with magnetic excitations of the multiferroic oxide BaCo$_2$Ge$_2$O$_7$,"We propose that concurrently magnetic and ferroelectric, i.e. multiferroic,
+compounds endowed with electrically-active magnetic excitations
+(electromagnons) provide a key to produce large directional dichroism for long
+wavelengths of light. By exploiting the control of ferroelectric polarization
+and magnetization in a multiferroic oxide Ba$_2$CoGe$_2$O$_7$, we demonstrate
+the realization of such a directional light-switch function at terahertz
+frequecies in resonance with the electromagnon absorption. Our results imply
+that this hidden potential is present in a broad variety of multiferroics.",1010.5420v1
+2014-12-25,Cu codoping control over magnetic precipitate formation in ZnCoO nanowires,"Using electrodeposition, we have grown nanowires of ZnCoO with Cu codoping
+concentrations varying from 4-10 at.%, controlled only by the deposition
+potential. We demonstrate control over magnetic Co oxide nano-precipitate
+formation in the nanowires via the Cu concentration. The different magnetic
+behavior of the Co oxide nano-precipitates indicates the potential of ZnCoO for
+magnetic sensor applications.",1412.7792v1
+2014-05-11,Tuning perpendicular magnetic anisotropy in the MgO/CoFeB/Ta thin films,"Understanding the magnetic anisotropy at ferromagnetic metal/oxide interface
+is a fundamental and intriguing subject. Here we propose an approach to
+manipulate the strength of perpendicular magnetic anisotropy (PMA) by varying
+MgO thickness in the MgO/CoFeB/Ta thin films. We identify that the PMA at the
+MgO/CoFeB interface is tuned by the crystalline structure of bulk MgO layer and
+decreases dramatically due to the onset of crystalline MgO forming with the
+increase of MgO thickness. Our work opens an avenue to manipulate the magnetic
+anisotropy by the modification of the ferromagnetic metal/oxide interface.",1405.2551v2
+2012-05-02,Strain and structure driven complex magnetic ordering of a CoO overlayer on Ir(100),"We have investigated the magnetic ordering in the ultrathin c(10$\times$2)
+CoO(111) film supported on Ir(100) on the basis of ab-initio calculations. We
+find a close relationship between the local structural properties of the oxide
+film and the induced magnetic order, leading to alternating ferromagnetically
+and anti-ferromagnetically ordered segments. While the local magnetic order is
+directly related to the geometric position of the Co atoms, the mismatch
+between the CoO film and the Ir substrate leads to a complex long-range order
+of the oxide.",1205.0493v1
+2018-03-21,Self-assembly of magnetic iron oxide nanoparticles into cuboidal superstructures,"This chapter describes the synthesis and some characteristics of magnetic
+iron oxide nanoparticles, mainly nanocubes, and focus on their self-assembly
+into crystalline cuboids in dispersion. The influence of external magnetic
+fields, the concentration of particles, and the temperature on the assembly
+process is experimentally investigated.",1803.07922v1
+2009-06-08,"Enhanced magnetism, memory and aging in Gold-Iron oxide nanoparticle composites","In this report we present systematic magnetic studies of pure iron oxide
+nanoparticles and gold iron oxide nanocomposite with increasing Au particle
+size/content. For the magnetic studies of these samples we have measured: (1)
+zero field cooled (ZFC) and field cooled (FC) magnetization, (2) ac
+susceptibility, (3) magnetization vs field at various temperatures, (4)
+thermoremanant magnetization relaxation (TRM) and zero field cooled
+magnetization relaxation (ZFCM) at fixed temperature for various wait times tw
+for studying the aging effect, (5) magnetization memory effect and (6) exchange
+bias as a function of cooling field. The detailed magnetic measurement analysis
+indicates that the pure Fe3O4 nanoparticles sample behaves like a
+superparamagnet and on incorporation of gold (Au) nanoparticles the
+nanocomposite system slowly evolves from superparamagnetic to superspin glass
+state. The memory and aging effect enhances with the increase of the Au
+nanoparticle size/content. The most important observation in this study is the
+enhancement of magnetization with the incorporation of Au nanoparticles. The
+enhancement increases with the increase in the Au content in the nanocomposite.
+We have explained the cause of this enhancement of magnetization as due to
+large orbital magnetic moment formation at the Au/magnetic particle interface.",0906.1497v2
+2017-03-13,High density nonmagnetic cobalt in thin films,"Recently high density (HD) nonmagnetic (NM) cobalt has been discovered in a
+cobalt thin film, grown on Si(111). This cobalt film had a natural cobalt oxide
+at the top. The oxide layer forms when the film is taken out of the
+electron-beam deposition chamber and exposed to air. Thin HD NM cobalt layers
+were found near the cobalt/silicon and the cobalt-oxide/cobalt interfaces,
+while the thicker mid-depth region of the film was hcp cobalt with normal
+density and normal magnetic moment. If an ultrathin film of gold is grown on
+the cobalt layer, before exposing it to air, the oxidation of the cobalt
+surface layer is prevented. It is important to investigate whether the growth
+of HD NM cobalt layers in the thin film depends on (i) capping of the film by
+the gold layer, (ii) the film thickness and (iii) the nature of the substrate.
+The results of such investigations, presented here, indicates that for cobalt
+films capped with a thin gold layer, and for various film thicknesses, HD NM
+cobalt layers are still observed. However, instead of a Si substrate, when the
+cobalt films are grown on oxide substrates, such as silicon oxide or cobalt
+oxide, HD NM cobalt layers are not observed.",1703.04270v1
+2021-10-05,Formation of a stable surface oxide in MnBi$_2$Te$_4$ thin films,"Understanding the air-stability of MnBi$_2$Te$_4$ thin films is crucial for
+the development and long-term operation of electronic devices based around
+magnetic topological insulators. In the present work, we study MnBi$_2$Te$_4$
+thin films upon exposure to atmosphere using a combination of synchrotron-based
+photoelectron spectroscopy, room temperature electrical transport and atomic
+force microscopy to determine the oxidation process. After 2 days air exposure
+a 2 nm thick oxide passivates the surface, corresponding to oxidation of only
+the top two surface layers, with the underlying layers preserved. This
+protective oxide layer results in samples that still exhibit metallic
+conduction even after several days air exposure. Furthermore, the work function
+decreases from 4.4 eV for pristine MnBi$_2$Te$_4$ to 4.0 eV after the formation
+of the oxide, along with only a small shift in the core levels indicating
+minimal doping as a result of air exposure. With the oxide confined to the top
+surface layers, and the underlying layers preserved, it may be possible to
+explore new avenues in how to handle, prepare and passivate future
+MnBi$_2$Te$_4$ devices.",2110.02412v1
+2015-11-11,Characterization of Magnetic Ni Clusters on Graphene Scaffold after High Vacuum Annealing,"Magnetic Ni nanoclusters were synthesized by electron beam deposition
+utilizing CVD graphene as a scaffold. The subsequent clusters were subjected to
+high vacuum (5-8 x10-7 torr) annealing between 300 and 600 0C. The chemical
+stability, optical and morphological changes were characterized by X-ray
+photoemission microscopy, Raman spectroscopy, atomic force microscopy and
+magnetic measurement. Under ambient exposure, nickel nanoparticles was observed
+to be oxidized quickly, forming antiferromagnetic nickel oxide. Here, we report
+that the majority of the oxidized nickel is in non-stoichiometric form and can
+be reduced under high vacuum at temperature as low as 300 0C. Importantly, the
+resulting annealed clusters are relatively stable and no further oxidation was
+detectable after three weeks of air exposure at room temperature.",1511.03349v1
+2016-04-04,Reversibly switchable electromagnetic device with leakage-free electrolyte,"Electrical control of oxygen off-stoichiometry of transition-metal oxides at
+room temperature is a desired strategy to simultaneously switch the electrical
+conductance and magnetism of the device. Although the use of the
+electrochemical redox reaction of transition-metal oxides is the most
+reasonable way to achieve the aforementioned switch, such a device has not been
+realized because of the lack of a leakage-free liquid electrolyte. Here, we
+demonstrate an electromagnetic device that can reversibly switch a
+transition-metal oxide from an insulator/non-magnet to a metal/magnet (Tc=275
+K) using a newly developed 'leakage-free electrolyte', incorporated in an
+amorphous NaTaO3 nanopillar array film. Reversible switching occurs
+electrically, obeying Faraday's laws of electrolysis, under a DC voltage of
++(-)3 V within 2-3 s at RT. The present electromagnetic device does not have
+the drawback of liquid leakage, and the leakage-free electrolyte provides a
+novel design concept for practical electromagnetic devices using
+transition-metal oxides.",1604.00824v1
+2013-08-06,Ion irradiation of Fe-Fe oxide core-shell nanocluster films: Effect of interface on stability of magnetic properties,"A cluster deposition method was used to produce films of loosely aggregated
+nanoclusters (NC) of Fe core-Fe3O4 shell or fully oxidized Fe3O4. Films of
+these NC on Si(100) or MgO(100)/Fe3O4(100) were irradiated to 10^16 Si2+/cm2
+near room temperature using an ion accelerator. Ion irradiation creates
+structural change in the NC film with corresponding chemical and magnetic
+changes which depend on the initial oxidation state of the cluster. Films were
+characterized using magnetometry (hysteresis, first order reversal curves),
+microscopy (transmission electron, helium ion), and x-ray diffraction. In all
+cases, the particle sizes increased due to ion irradiation, and when a core of
+Fe is present, irradiation reduces the oxide shells to lower valent Fe species.
+These results show that ion irradiated behavior of the nanocluster films
+depends strongly on the initial nanostructure and chemistry, but in general
+saturation magnetization decreases slightly.",1308.1384v1
+2017-12-13,Two-dimensional electron system at the magnetically tunable EuO/SrTiO$_3$ interface,"We create a two-dimensional electron system (2DES) at the interface between
+EuO, a ferromagnetic insulator, and SrTiO3, a transparent non-magnetic
+insulator considered the bedrock of oxide-based electronics. This is achieved
+by a controlled in-situ redox reaction between pure metallic Eu deposited at
+room temperature on the surface of SrTiO3, an innovative bottom-up approach
+that can be easily generalized to other functional oxides and scaled to
+applications. Additionally, we find that the resulting EuO capping layer can be
+tuned from paramagnetic to ferromagnetic, depending on the layer thickness.
+These results demonstrate that the simple, novel technique of creating 2DESs in
+oxides by deposition of elementary reducing agents [T. C. R\""odel et al., Adv.
+Mater. 28, 1976 (2016)] can be extended to simultaneously produce an active,
+e.g. magnetic, capping layer enabling the realization and control of additional
+functionalities in such oxide-based 2DESs.",1712.04891v1
+2017-09-28,New Approach to Determine the Quality of Graphene,"The reduction of graphene oxide is one of the most facile methods to
+fabricate a large amount of graphene and the reduction rate of graphene oxide
+is related with the quality of synthesized graphene for its possible
+application. The reduction rate is usually determined by using various
+spectroscopy measurements such as Raman spectroscopy, Fourier transform
+infrared spectroscopy, and X-ray photoelectron spectroscopy. Here we propose
+that the magnetic data can be used as a means of determining the quality of
+graphene oxide (GO) and reduced graphene oxide (RGO) by the investigation of
+close relation between magnetic moment and chemical bonding state. Our
+experimental findings and previous theoretical studies suggest that hydroxyl
+functional groups in GO mainly contribute to Langevin paramagnetism, carboxyl
+functional groups in RGO1 act as the source for Pauli paramagnetism, and sp2
+bonding state in RGO2 plays a major role on the diamagnetism. Especially in
+terms of mass production, the magnetic data is useful for decomposing the
+chemical bonding electronic states in graphene-like samples and judging their
+quality.",1709.09879v1
+2004-07-23,"High Pressure Effects on Superconductivity in the beta-pyrochlore Oxides AOs2O6 (A=K, Rb, Cs)","Recently new pyrochlore oxides superconductors AOs2O6 (A=K,Rb,Cs) were found
+and we measured the pressure dependence of magnetization up to 1.2 GPa in order
+to deduce the pressure effect of Tc in the three beta-pyrochlore oxides. It is
+found that the initial pressure dependence of Tc is positive for all the
+compounds. Only KOs2O6 exhibits a saturation in Tc at 0.56 GPa and the downturn
+at higher pressure",0407610v1
+2005-04-26,Spin filtering through ferromagnetic BiMnO3 tunnel barriers,"We report on experiments of spin filtering through ultra-thin single-crystal
+layers of the insulating and ferromagnetic oxide BiMnO3 (BMO). The spin
+polarization of the electrons tunneling from a gold electrode through BMO is
+analyzed with a counter-electrode of the half-metallic oxide La2/3Sr1/3MnO3
+(LSMO). At 3 K we find a 50% change of the tunnel resistances according to
+whether the magnetizations of BMO and LSMO are parallel or opposite. This
+effect corresponds to a spin filtering effciency of up to 22%. Our results thus
+show the potential of complex ferromagnetic insulating oxides for spin
+filtering and injection.",0504667v1
+2007-02-17,"Metal-insulator Transition in a Pyrochlore-type Ruthenium oxide, Hg2Ru2O7","A new pyrochlore ruthenium oxide, Hg2Ru2O7 was synthesized under a high
+pressure of 6 GPa. In contrast to the extensively studied Ru4+ oxides, this
+compound possesses a novel Ru5+ valence state, corresponding to a half-filled
+t_2g_3 electron configuration. Hg2Ru2O7 exhibits a first order metal-insulator
+transition at 107 K, accompanied by a structural transition from cubic to lower
+symmetry. The behavior of the magnetic susceptibility suggests the possible
+formation of a spin singlet in the insulating low temperature state.",0702411v1
+2014-09-16,Tuning ferromagnetism at interfaces between insulating perovskite oxides,"We use density functional theory calculations to show that the LaAlO3|SrTiO3
+interface between insulating perovskite oxides is borderline in satisfying the
+Stoner criterion for itinerant ferromagnetism and explore other oxide
+combinations with a view to satisfying it more amply. The larger lattice
+parameter of an LaScO3|BaTiO3 interface is found to be less favorable than the
+greater interface distortion of LaAlO3|CaTiO3. Compared to LaAlO3|SrTiO3, the
+latter is predicted to exhibit robust magnetism with a larger saturation moment
+and a higher Curie temperature. Our results provide support for a ""two phase""
+picture of coexistent superconductivity and ferromagnetism.",1409.4554v1
+2015-02-08,Change in sign of the Hall coefficient from Fermi surface curvature in underdoped high Tc copper oxide superconductors,"It has recently been proposed that the Fermi surface of underdoped high Tc
+copper oxide materials within the charge-ordered regime consists of a
+diamond-shaped electron pocket constructed from arcs connected at vertices. We
+show here that on modeling the in-plane magnetotransport of such a Fermi
+surface using the Shockley-Chambers tube integral approach and a uniform
+scattering time, several key features of the normal state in-plane transport of
+the underdoped copper oxide systems can be understood. These include the sign
+reversal in the Hall coefficient, the positive magnetoresistance and magnetic
+quantum oscillations in the Hall coefficient.",1502.02273v1
+2015-03-03,Resolution of SU(2) monopole singularities by oxidation,"We show how ""colored"" SU(2) BPS monopoles (that is: SU(2) monopoles
+satisfying the Bogomol'nyi equation whose Higgs field and magnetic charge
+vanish at infinity and which are singular at the origin) can be obtained from
+the BPST instanton by a singular dimensional reduction, explaining the origin
+of the singularity and implying that the singularity can be cured by the
+oxidation of the solution. We study the oxidation of other monopole solutions
+in this scheme.",1503.01044v1
+2015-09-14,Multi-Fields Modulation of Physical Properties of Oxide Thin Films,"Oxide thin films exhibit versatile physical properties such as magnetism,
+ferroelectricity, piezoelectricity, metal-insulator transition (MIT),
+multiferroicity, colossal magnetoresistivity, switchable resistivity, etc. More
+importantly, the exhibited multifunctionality could be tuned by various
+external fields, which has enabled demonstration of novel electronic devices.
+In this article, recent studies of the multi-fields modulation of physical
+properties in oxide thin films have been reviewed. Some of the key issues and
+prospects about this field are also addressed.",1509.03939v1
+2017-09-26,Spintronic Functionalities in Multiferroic Oxide-based Heterostructures,"The list of materials systems displaying both electric and magnetic long
+range order is short. Oxides, however, concentrate numerous examples of
+multiferroicity with, in some cases, a large magnetoelectric coupling. As a
+result, a fruitful research field has emerged contemporaneously with the
+consolidation of spintronic. The synergy between multiferroics and spintronics
+was meant to be inevitable and hence the characterization of spintronic
+functionalities in multiferroic materials is rather abundant. The aim of the
+present chapter is to review the oxide heterostructures where magnetoelectric
+coupling is demonstrated by means of spintronic functionalities (i.e.
+magnetoresistance, anisotropic magnetoresistance, giant magnetoresistance or
+tunnel magnetoresistance).",1709.08918v1
+2023-11-10,Observation of the out-of-plane orbital antidamping-like torque,"The out-of-plane antidamping-like orbital torque fosters great hope for
+high-efficiency spintronic devices. Here we report experimentally the
+observation of out-of-plane antidamping-like torque that could be generated by
+z-polarized orbital current in ferromagnetic-metal/oxidized Cu bilayers, which
+is presented unambiguously by the magnetic field angle dependence of
+spin-torque ferromagnetic resonance signal. The oxidized Cu thickness
+dependence of orbital torque ratios highlights the interfacial effect would be
+responsible for the generation of orbital current. Besides that, the oxidized
+Cu thickness dependence of damping parameter further proves the observation of
+antidamping-like torque. This result contributes to enriching the
+orbital-related theory of the generation mechanism of the orbital torque.",2311.05868v1
+1996-06-05,Transport and magnetic properties in ferromagnetic manganese-oxide thin films,"The transport and magnetic properties in ferromagnetic manganese-oxide thin
+films are studied based on the model of the coupling between the mobile
+d-electrons and the core spins in Mn ions. The spontaneous magnetization and
+the resistivity are obtained for various magnetic fields and temperature. The
+resistivity in absence of magnetic field and the magnetoresistance exhibit
+maxima near the Curie temperature, the applied magnetic field moves the
+position of the resistivity peak to high temperature and suppresses the peak
+value, which agree with the experimental results. The Hall resistivity is
+predicted to exhibit maximum near the Curie point. The pressure effect of the
+magnetoresistance can also be explained qualitatively in this mechanism. The
+colossal magnetoresistance in ferromagnetic manganese-oxide thin films is
+attributed to the spin-correlation fluctuation scattering and the low
+dimensional effect.",9606029v1
+2015-09-03,Interfacial Magnetism in Complex Oxide Heterostructures Probed by Neutrons and X-rays,"Magnetic complex-oxide heterostructures are of keen interest because a wealth
+of phenomena at the interface of dissimilar materials can give rise to
+fundamentally new physics and potentially valuable functionalities. Altered
+magnetization, novel magnetic coupling and emergent interfacial magnetism at
+the epitaxial layered-oxide interfaces are under intensive investigation, which
+shapes our understanding on how to utilize those materials, particularly for
+spintronics. Neutron and x-ray based techniques have played a decisive role in
+characterizing interfacial magnetic structures and clarifying the underlying
+physics in this rapidly developing field. Here we review some recent
+experimental results, with an emphasis on those studied via polarized neutron
+reflectometery and polarized x-ray absorption spectroscopy. We conclude with
+some perspectives.",1509.00912v1
+2016-04-28,Incommensurate spin correlations in highly oxidized cobaltates La$_{2-x}$Sr$_{x}$CoO$_{4}$,"We observe quasi-static incommensurate magnetic peaks in neutron scattering
+experiments on layered cobalt oxides La2-xSrxCoO4 with high Co oxidation states
+that have been reported to be paramagnetic. This enables us to measure the
+magnetic excitations in this highly hole-doped incommensurate regime and
+compare our results with those found in the low-doped incommensurate regime
+that exhibit hourglass magnetic spectra. The hourglass shape of magnetic
+excitations completely disappears given a high Sr doping. Moreover, broad
+low-energy excitations are found, which are not centered at the incommensurate
+magnetic peak positions but around the quarter-integer values that are
+typically exhibited by excitations in the checkerboard charge ordered phase.
+Our findings suggest that the strong inter-site exchange interactions in the
+undoped islands are critical for the emergence of hourglass spectra in the
+incommensurate magnetic phases of La2-xSrxCoO4.",1604.08389v1
+2018-10-23,Absence of a multiglass state in some transition metal doped quantum paraelectrics,"We critically investigate the purported existence of a multiglass state in
+the quantum paraelectrics SrTiO${_3}$ and KTaO${_3}$ doped with magnetic 3d
+transition metals. We observe that the transition metals have limited
+solubility in these hosts, and that traces of impurity magnetic oxides persist
+even in the most well processed specimens. Our dielectric measurements indicate
+that the polar nano-regions formed as a consequence of doping appear to lack
+co-operativity, and the associated relaxation process exhibits a thermally
+activated Arrhenius form. At lower temperatures, the dielectric susceptibility
+could be fit using the Barrett's formalism, indicating that the
+quantum-paraelectric nature of the host lattices are unaltered by the doping of
+magnetic transition metal oxides. All these doped quantum paraelectrics exhibit
+a crossover from the high temperature Curie-Weiss regime to one dominated by
+quantum fluctuations, as evidenced by a $T{^2}$ dependence of the temperature
+dependent dielectric susceptibility. The temperature dependence of the magnetic
+susceptibility indicate that magnetic signatures observed in some of the
+specimens could be solely ascribed to the presence of impurity oxides
+corresponding to the magnetic dopants used. Hence, the doped quantum
+paraelectrics appear to remain intrinsically paramagnetic down to the lowest
+measured temperatures, ruling out the presence of a multiglass state.",1810.09822v1
+2013-06-25,Efficient spin injection through a crystalline AlOx tunnel barrier prepared by the oxidation of an ultra-thin Al epitaxial layer on GaAs,"We report that an ultra-thin, post-oxidized aluminum epilayer grown on the
+AlGaAs surface works as a high-quality tunnel barrier for spin injection from a
+ferromagnetic metal to a semiconductor. One of the key points of the present
+oxidation method is the formation of the crystalline AlOx template layer
+without oxidizing the AlGaAs region near the Al/AlGaAs interface. The oxidized
+Al layer is not amorphous but show well-defined single crystalline feature
+reminiscent of the spinel gamma-AlOx phase. A spin-LED consisting of an Fe
+layer, a crystalline AlOx barrier layer, and an AlGaAs-InGaAs double
+hetero-structure has exhibited circularly polarized electroluminescence with
+circular polarization of P_{EL} = 0.145 at the remnant magnetization state of
+the Fe layer, indicating the relatively high spin injection efficiency (epsilon
+= 2P_{EL} / P_{Fe}) of 0.63.",1306.5847v1
+2014-04-09,A high Neel temperature 5$d$ oxide: NaOsO$_3$,"The origin of a high Neel temperature in a 5$d$ oxide, NaOsO$_3$, has been
+analyzed within the mean-field limit of a multiband Hubbard model and compared
+with the analogous 4$d$ oxide, SrTcO$_3$. Our analysis shows that there are a
+lot of similarities in both these oxides on the dependence of the the effective
+exchange interaction strength ($J_0$) on the electron-electron interaction
+strength ($U$). However, the relevant value of $U$ in each system puts them in
+different portions of the parameter space. Although the Neel temperature for
+NaOsO$_3$ is less than that for SrTcO$_3$, our results suggest that there could
+be examples among other 5$d$ oxides which have a higher Neel temperature. We
+have also examined the stability of the G-type antiferromagnetic state found in
+NaOsO$_3$ as a function of electron doping within GGA+U calculations and find a
+robust G-type antiferromagnetic metallic state stabilized. The most surprising
+aspect of the doped results is the rigid band-like evolution of the electronic
+structure which indicates that the magnetism in NaOsO$_3$ is not driven by
+fermi surface nesting.",1404.2356v1
+2015-09-02,The characterization of Co-nanoparticles supported on graphene,"The results of density functional theory calculations and measurements using
+X-ray photoelectron spectroscopy of Co-nanoparticles dispersed on graphene/Cu
+are presented. It is found that for low cobalt thickness (0.02 nm - 0.06 nm)
+the Co forms islands distributed non-homogeneously which are strongly oxidized
+under exposure to air to form cobalt oxides. At greater thicknesses up to 2 nm
+the upper Co-layers are similarly oxidized whereas the lower layers contacting
+the graphene remain metallic. The measurements indicate a Co2+ oxidation state
+with no evidence of a 3+ state appearing at any Co thickness, consistent with
+CoO and Co[OH]2. The results show that thicker Co (2nm) coverage induces the
+formation of a protective oxide layer while providing the magnetic properties
+of Co nanoparticles.",1509.00575v1
+2015-09-10,Role of hexagonal boron nitride in protecting ferromagnetic nanostructures from oxidation,"Ferromagnetic contacts are widely used to inject spin polarized currents into
+non-magnetic materials such as semiconductors or 2-dimensional materials like
+graphene. In these systems, oxidation of the ferromagnetic materials poses an
+intrinsic limitation on device performance. Here we investigate the role of
+ex-situ transferred chemical vapour deposited hexagonal boron nitride (hBN) as
+an oxidation barrier for nanostructured cobalt and permalloy electrodes. The
+chemical state of the ferromagnets was investigated using X-ray photoemission
+electron microscopy owing to its high sensitivity and lateral resolution. We
+have compared the oxide thickness formed on ferromagnetic nanostructures
+covered by hBN to uncovered reference structures. Our results show that hBN
+reduces the oxidation rate of ferromagnetic nanostructures suggesting that it
+could be used as an ultra-thin protection layer in future spintronic devices.",1509.03087v2
+2020-07-15,Structure and Properties of Thermoresponsive Diblock Copolymers Embedded with Metal Oxide Nanoparticles,"Nanostructured polymer-metal oxide composites are a current research area of
+great importance due to its highlight applications in sensors, optics,
+catalysts and drug delivery. Particularly the use of thermoresponsive polymers
+gives more flexibilities and possibilities in the design and construction of
+polymer templates. In the present investigation, the structure and magnetic
+properties of hybrid metal oxide/DBC films composed of two kinds of
+polystyrene-block-poly (N-isopropylacrylamide)(PS-b-PNIPAM) diblock copolymers
+(DBCs) with PS and PNIPAM as the major polymer domains respectively, and iron
+oxide were investigated. The thermoresponsive PNIPAM has a lower critical
+solution temperature (LCST) in aqueous solution at 32{\deg}C, which enables the
+controllable volume ratio of PS and PNIPAM in the structure of PS-b-PNIPAM
+diblock copolymers (DBCs). Thus, a temperature and humidity controlling cell
+was designed and built for precisely tuning the block structure of PS-b-PNIPAM
+DBCs, which was investigated by in-situ small-angle X-ray scattering (SAXS) and
+grazing-incidence small-angle X-ray scattering (GISAXS) measurements. The
+superparamagnetic behavior of the heat-treated hybrid iron oxide/PS-b-PNIPAM
+DBC films was investigated using a superconducting quantum interference device
+(SQUID) magnetometer.",2007.10111v1
+2017-04-17,Structural Distortions At Polar Manganite Interfaces,"Electronic, lattice, and spin interactions at the interfaces between
+crystalline complex transition metal oxides can give rise to a wide range of
+functional electronic and magnetic phenomena not found in bulk. At
+hetero-interfaces, these interactions may be enhanced by combining oxides where
+the polarity changes at the interface. The physical structure between non-polar
+SrTiO$_3$ and polar La$_{1-x}$Sr$_x$MnO$_3$(x=0.2) is investigated using high
+resolution synchrotron x-ray diffraction to directly determine the role of
+structure in compensating the polar discontinuity. At both the oxide-oxide
+interface and vacuum-oxide interfaces, the lattice is found to expand and
+rumple along the growth direction. The SrTiO$_3$/La$_{1-x}$Sr$_x$MnO$_3$
+interface also exhibits intermixing of La and Sr over a few unit cells. The
+results, hence, demonstrate that polar distortions and ionic intermixing
+coexist and both pathways play a significant role at interfaces with polar
+discontinuities.",1704.05114v2
+2021-02-10,Controlling the oxidation of magnetic and electrically conductive solid-solution iron-rhodium nanoparticles synthesized by Laser Ablation in Liquids,"This study focuses on the synthesis of FeRh nanoparticles via pulsed laser
+ablation in liquid and on controlling the oxidation of the synthesized
+nanoparticles. Formation of monomodal {\gamma}-FeRh nanoparticles was confirmed
+by transmission electron microscopy (TEM) and their composition confirmed by
+atom probe tomography (APT). On these particles, three major contributors to
+oxidation were analysed: 1) dissolved oxygen in the organic solvents, 2) the
+bound oxygen in the solvent and 3) oxygen in the atmosphere above the solvent.
+The decrease of oxidation for optimized ablation conditions was confirmed
+through energy-dispersive X-ray (EDX) and M\""ossbauer spectroscopy.
+Furthermore, the time dependence of oxidation was monitored for dried FeRh
+nanoparticles powders using ferromagnetic resonance spectroscopy (FMR). By
+magnetophoretic separation, B2-FeRh nanoparticles could be extracted from the
+solution and characteristic differences of nanostrand formation between
+{\gamma}-FeRh and B2-FeRh nanoparticles were observed.",2102.05652v1
+2021-04-16,"Structural phase stability, electronic structure, magnetic properties and chemical bonding analysis of transition metal ammine borohydrides with amphoteric hydrogen for hydrogen storage","Usually the ions of a particular element in solids are in positive or
+negative oxidation states, depending upon the chemical environment. It is
+highly unusual for an atom having both positive as well as negative oxidation
+states simultaneously within the same structural framework in a particular
+compound. Our structural and chemical bonding analyses show that the hydrogen
+ions in the transition metal ammine borohydrides (TMABHs) with the chemical
+formula M(BH4)2(NH3)2 (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) have both
+positive and negative oxidation states. Our detailed analyses confirm the
+amphoteric behaviour of hydrogen where hydrogen closer to boron is in negative
+oxidation state and that closer to nitrogen is in the positive oxidation state.
+From the spin polarised van der Waals interaction included calculation, we
+found that TMABHs has antiferromagnetic ordering as ground state. Our nudged
+elastic band calculation show that the migration barrier for ammonia diffusion
+in these materials are more than 1 eV and hence these compounds may be used for
+energy storage applications since they have high weight percentage of hydrogen.
+The presence of amphoteric behaviour of hydrogen in TMABHs has implication in
+designing volume efficient hydrides for hydrogen storage applications.",2104.08140v1
+2022-06-02,Defect Profiling of Oxide-Semiconductor Interfaces Using Low-Energy Muons,"Muon spin rotation with low-energy muons (LE{\mu}SR) is a powerful nuclear
+method where electrical and magnetic properties of surface-near regions and
+thin films can be studied on a length scale of $\approx$\SI{200}{\nano\meter}.
+In this work, we show the potential of utilizing low-energy muons for a
+depth-resolved characterization of oxide-semiconductor interfaces, i.e. for
+silicon (Si) and silicon carbide (4H-SiC). Silicon dioxide (SiO$_2$) grown by
+plasma-enhanced chemical vapor deposition (PECVD) and by thermal oxidation of
+the SiO$_2$-semiconductor interface are compared with respect to interface and
+defect formation. The nanometer depth resolution of {\mu}allows for a clear
+distinction between the oxide and semiconductor layers, while also quantifying
+the extension of structural changes caused by the oxidation of both Si and SiC.",2206.00925v1
+2022-08-04,Reversible Tuning of Collinear versus Chiral Magnetic Order by Chemical Stimulus,"The Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction mediates collinear
+magnetic interactions via the conduction electrons of a non-magnetic spacer,
+resulting in a ferro- or antiferromagnetic magnetization in magnetic
+multilayers. The resulting spin-polarized charge transport effects have found
+numerous applications. Recently it has been discovered that heavy non-magnetic
+spacers are able to mediate an indirect magnetic coupling that is non-collinear
+and chiral. This Dzyaloshinskii-Moriya-enhanced RKKY (DME-RKKY) interaction
+causes the emergence of a variety of interesting magnetic structures, such as
+skyrmions and spin spirals. Applications using these magnetic quasi-particles
+require a thorough understanding and fine-tuning of the balance between the
+Dzyaloshinskii-Moriya interaction and other magnetic interactions, e.g., the
+exchange interaction and magnetic anisotropy contributions. Here, we show by
+spin-polarized scanning tunneling microscopy that the spin structure of
+manganese oxide chains on Ir(001) can reproducibly be switched from chiral to
+collinear antiferromagnetic interchain interactions by increasing the oxidation
+state of MnO$_2$ while the reverse process can be induced by thermal reduction.
+The underlying structural change is revealed by low-energy electron diffraction
+intensity data (LEED-IV) analysis. Density functional theory calculations
+suggest that the magnetic transition may be caused by a significant increase of
+the Heisenberg exchange upon oxidation.",2208.02570v1
+2020-04-14,"On the Elastic Anisotropy of the Entropy-Stabilized Oxide (Mg, Co, Ni, Cu, Zn)O","In this paper, we study the elastic properties of the entropy-stabilized
+oxide (Mg, Co, Ni, Cu, Zn)O, using experimental and first principles
+techniques. Our measurements of the indentation modulus on grains with a wide
+range of crystallographic orientations of the entropy-stabilized oxide revealed
+a high degree of elastic isotropy at ambient conditions. First principles
+calculations predict mild elastic anisotropy for the paramagnetic structure,
+which decreases when the system is considered to be non-magnetic. When the
+antiferromagnetic state of CoO, CuO and NiO is accounted for in the
+calculations, a slight increase in the elastic anisotropy is observed,
+suggesting a coupling between magnetic ordering and the orientation dependent
+elastic properties. Furthermore, an examination of the local structure reveals
+that the isotropy is favored through local ionic distortions of Cu and Zn - due
+to their tendency to form tenorite and wurtzite phases. The relationships
+between the elastic properties of the multicomponent oxide and those of its
+constituent binary oxides are reviewed. These insights open up new avenues for
+controlling isotropy for technological applications through tuning composition
+and structure in the entropy-stabilized oxide or the high entropy compounds in
+general.",2004.06613v1
+2012-05-22,Observation of 0 to pi transition in YBCO/Gallium oxide multilayers,"When two superconductors are coupled via an insulator the phase difference
+between them is expected to be zero in the ground state and such Josephson
+junctions are known as ""0"" type Josephson junctions . But in the presence of
+magnetic impurities in the barrier or ferromagnetism, the phase difference in
+the ground state could become pi; such Josephson junctions are known as ""pi""
+type Josephson junctions1-4. Experimental results have confirmed the
+observation of a 0 to pi transition as a function of temperature in Josephson
+junctions such as Nb/Cu1-xNix/Nb based on ferromagnetic weak links with low
+exchange energy5. Recently, observation of possible magnetic behaviour in
+oxides has been reported6,7, and it would, therefore, be interesting to study
+the Josephson coupling in YBCO/gallium oxide multilayers. This work reports the
+observation of a very anomalous superconducting behaviour in YBCO/gallium oxide
+multilayers. A transition to the superconducting state has been observed with
+an enhanced superconducting transition temperature of 98 K in the YBCO/gallium
+oxide multilayer followed by a second transition temperature at 90 K with the
+multilayer losing its superconductivity at intermediate temperatures. This
+behaviour is explained by assuming that the Josephson coupling between the
+superconducting YBCO layers in the multilayer changes from pi type to 0 type.
+This is the first experimental observation of the 0 to pi transition in
+HTSC/gallium oxide/HTSC thin film structures.",1205.4869v1
+2022-12-04,Explore of exfoliable multifunctional high-k two-dimensional oxides,"As the continuing down-scaling of field-effect transistors (FETs) in
+more-than-Moore integrated circuits, finding new functional two-dimensional
+(2D) materials with a higher dielectric constant (high-k) serve as gate
+dielectrics is critical. Here, we identify dozens of binary 2D oxides by
+screening potentially exfoliable bulk metal oxides despite of their non-layered
+structures followed by simulation of the exfoliation process. For dynamically
+stable materials, we fully characterize their static dielectric constants and
+electronic structures, among which GeO2(011)/(101)/(1-11) 2D oxides exhibit
+unusually high k values (85-99), being much higher than the k of the currently
+highly regarded 2D dielectrics CaF2 (k ~6) and \b{eta}-Bi2SeO5 (k ~22),
+together with band gap of 3.3 eV. We further design 2D high-k oxides/2D
+semiconductors (such as MoS2) heterostructures, and determine by DFT
+calculations whether they can form Van der Waals interfaces to evaluate their
+compatibility as gate dielectrics in 2D FETs. In addition to dielectric
+properties, we also explore magnetic and mechanical properties of potentially
+exfoliable 2D oxides, revealing a number of functional materials that can be
+studied experimentally, notably including ferromagnetic half semiconductors,
+non-magnetic spintronic materials, flexible high-k 2D oxides, and auxetic
+monolayers.",2212.01731v1
+2024-03-03,Crystal Structure and Magnetism of Actinide Oxides: A Review,"In actinide systems, the 5f electrons experience a uniquely delicate balance
+of effects and interactions having similar energy scales, which are often
+difficult to properly disentangle. This interplay of factors such as the dual
+nature of 5f-states, strong electronic correlations, and strong spin-orbit
+coupling results in electronically unusual and intriguing behavior such as
+multi-k antiferromagnetic ordering, multipolar ordering, mott-physics, mixed
+valence configurations, and more. Despite the inherent allure of their exotic
+properties, the exploratory science of even the more basic, binary systems like
+the actinide oxides has been limited due to their toxicity, radioactivity, and
+reactivity. In this article, we provide an overview of the available synthesis
+techniques for selected binary actinide oxides, including the actinide
+dioxides, sesquioxides, and a selection of higher oxides. For these oxides, we
+also review and evaluate the current state of knowledge of their crystal
+structures and magnetic properties. In many aspects, substantial knowledge gaps
+exist in the current body of research on actinide oxides related to
+understanding their electronic ground states. Bridging these gaps is vital for
+improving not only a fundamental understanding of these systems but also of
+future nuclear technologies. To this end, we note the experimental techniques
+and necessary future investigations which may aid in better elucidating the
+nature of these fascinating systems.",2403.01634v1
+1999-02-18,Neutron Scattering from Magnetic Excitations in Bi_2 Sr_2 Ca_2 O_8+delta,"Many physical properties of the copper oxide high temperature superconductors
+appear to defy the conventional (one-electron) theory of metals, and the
+development of new theories incorporating strong electron correlations is
+currently at the forefront of condensed matter physics. Inelastic neutron
+scattering provides incisive information about collective magnetic excitations
+that is required to guide this effort. Such measurements have thus far proven
+possible for only two of the many families of high temperature superconductors,
+La_{2-x} Sr_x CuO_4 and YBa_2 Cu_3 O_{6+x},because suitably large single
+crystals of other copper oxide compounds could not be grown. While the magnetic
+spectra of both materials bear certain similarities, there are also pronounced
+differences that have hampered a unified description of the spin dynamics in
+the copper oxides. In particular, a sharp resonant spin excitation dominates
+the spectrum in the superconducting state of YBa_2 Cu_3 O_{6+x}, but is not
+found in La_{2-x} Sr_x CuO_4. Here we report the discovery of a magnetic
+resonance peak in the superconducting state of a different copper oxide system,
+Bi_2 Sr_2 Ca Cu_2 O_{8+\delta}, made possible by the synthesis of a sizable
+single crystal and modern neutron optics. This provides evidence of the
+generality of this unusual phenomenon among the copper oxides and greatly
+extends the empirical basis for its theoretical description.",9902262v2
+2021-09-05,Lateral modulation of magnetic anisotropy in tricolor 3d-5d oxide superlattices,"Manipulating magnetic anisotropy (MA) purposefully in transition metal oxides
+(TMOs) enables the development of oxide-based spintronic devices with practical
+applications. Here, we report a pathway to reversibly switch the lateral
+magnetic easy-axis via interfacial oxygen octahedral coupling (OOC) effects in
+3d-5d tricolor superlattices, i.e. [SrIrO3,mRTiO3,SrIrO3,2La0.67Sr0.33MnO3]10
+(RTiO3: SrTiO3 and CaTiO3). In the heterostructures, the anisotropy energy
+(MAE) is enhanced over one magnitude to ~106 erg/cm3 compared to
+La0.67Sr0.33MnO3 films. Moreover, the magnetic easy-axis is reversibly
+reoriented between (100)- and (110)-directions by changing the RTiO3. Using
+first-principles density functional theory calculations, we find that the
+SrIrO3 owns a large single-ion anisotropy due to its strong spin-orbit
+interaction. This anisotropy can be reversibly controlled by the OOC, then
+reorient the easy-axis of the superlattices. Additionally, it enlarges the MAE
+of the films via the cooperation with a robust orbital hybridization between
+the Ir and Mn atoms. Our results indicate that the tricolor superlattices
+consisting of 3d and 5d oxides provide a powerful platform to study the MA and
+develop oxide-based spintronic devices.",2109.02062v1
+2005-08-17,Magnetic properties in a partially oxidized nanocomposite of Cu-CuCl,"Magnetism of a very thin antiferromagnetic (AFM) surface CuO has been
+investigated with the partially oxidized nanocomposites of Cu-CuCl, ~ 200 nm.
+The samples are characterized by X-ray diffraction, X-ray photoelectron
+spectroscopy, X-ray-excited Auger electron spectroscopy, transmission electron
+microscope and magnetic measurements. The characterizations indicate that the
+composites have a core-shell structure. Before the oxidation, it is
+(Cu)core/(CuCl)shell, and after the oxidation,
+(Cu)core/(Cu2O+CuCl+minuteCuO)shell. The magnetic measurements have revealed
+that a ferromagnetic (FM) like open hysteresis exists at the temperature below
+the freezing point, TF. In the high field region, a paramagnetic (PM) response
+appears without showing a sign of saturation. Also, the field dependent
+magnetization (M-H) measurement is PM-like at T > TF. These interesting
+magnetic properties are evident to arise from the AFM CuO on the outer surface.
+They are attributed to the uncompensated surface spins of Cu2+ and the effect
+of surface random potential. More interestingly, the magnetic susceptibility is
+greatly enhanced in the presence of Cl- anions at T < TF, according to the
+field-cooled/zero-field-cooled (FC/ZFC) measurements. This further supports the
+point that the disorder or frustration effect of the impurity would reduce the
+AFM ordering of CuO and increase the level of uncompensated spins.",0508387v2
+2022-02-08,Tunable Magnetic Anisotropy in Patterned SrRuO3 Quantum Structures: Competition between Lattice Anisotropy and Oxygen Octahedral Rotation,"Artificial perovskite-oxide nanostructures possess intriguing magnetic
+properties due to their tailorable electron-electron interactions, which are
+extremely sensitive to the oxygen coordination environment. To date,
+perovskite-oxide nanodots with sizes below 50 nm have rarely been reported.
+Furthermore, the oxygen octahedral distortion and its relation to magnetic
+properties in perovskite oxide nanodots remain unexplored yet. Here, we have
+studied the magnetic anisotropy in patterned SrRuO3 (SRO) nanodots as small as
+30 nm while performing atomic-resolution electron microscopy and spectroscopy
+to directly visualize the constituent elements, in particular oxygen ions. We
+observe that the magnetic anisotropy and RuO6 octahedra distortion in SRO
+nanodots are both nanodots' size-dependent but remain unchanged in the first
+3-unit-cell interfacial SRO monolayers regardless of the dots' size. Combined
+with the first principle calculations, we unravel a unique structural mechanism
+behind the nanodots' size-dependent magnetic anisotropy in SRO nanodots,
+sugguesting that the competition between lattice anisotropy and oxygen
+octahedral rotation mediates anisotropic exchange interactions in SRO nanodots.
+These findings demonstrate a new avenue towards tuning magnetic properties of
+correlated perovskite oxides and imply that patterned nanodots could be a
+promising playground for engineering emergent functional behaviors.",2202.03820v1
+2015-11-14,Magnetic field induced augmented thermal conduction phenomenon in magneto nanocolloids,"Magnetic field induced drastically augmented thermal conductivity of magneto
+nanocolloids involving magnetic oxide nanoparticles, viz. Fe2O3, Fe3O4, Nickel
+oxide (NiO), Cobalt oxide (Co3O4), dispersed in different base fluids (heat
+transfer oil, kerosene, and ethylene glycol) have been reported. Experiments
+reveal the augmented thermal transport under the external applied magnetic
+field, with kerosene based MNCs showing at relatively low magnetic field
+intensities as compared to the heat transfer oil and EG based MNCs. A maximum
+thermal conductivity enhancement of 114 % is attained at 7.0 vol. %
+concentration and 0.1 T field intensity for Fe3O4/EG magneto nanocolloid.
+However, a maximum of 82% thermal conductivity enhancement is observed for
+Fe3O4/Kerosene magneto nanocolloid for the same concentration but relatively at
+low magnetic field (600 G). Thereby, a strong effect of fluid as well as
+particle physical properties on the chain formation propensity, leading to
+enhanced conduction, in such systems is observed. Co3O4 nanoparticles show
+insignificant effect on the thermal conductivity enhancement of MNCs due to
+their minimal magnetic moment. An analytical approach has been proposed to
+understand the mechanism and physics behind the thermal conductivity
+enhancement under external applied magnetic field, in tune with near field
+magnetostatic interactions as well as Neel relaxivity of the magnetic
+nanoparticles. Furthermore, the analytical model is able to predict the
+phenomenon of enhanced thermal conductivity as a function of physical
+parameters such as chain length, size and types of nanoparticles, fluid
+characteristics, magnetic field intensity, saturation magnetic moment,
+nanoparticle concentration etc. and good agreement with the experimental
+results has been observed.",1511.04560v1
+2021-02-24,Unusual direction-dependent magnetic orbital moment obtained from X-ray magnetic circular dichroism in a multiferroic oxide system,"The electric-field control of $d$-electron magnetism in multiferroic
+transition metal oxides is attracting widespread interest for the underlying
+fundamental physics and for next generation spintronic devices. Here, we report
+an extensive study of the $3d$ magnetism in magnetoelectric
+Ga$_{0.6}$Fe$_{1.4}$O$_3$ (GFO) epitaxial films by polarization dependent x-ray
+absorption spectroscopy. We found a non-zero integral of the x-ray magnetic
+circular dichroism, with a sign depending upon the relative orientation between
+the external magnetic field and the crystallographic axes. %By reliably
+enlarging the limit of the spin and orbital sum rules, which usually holds for
+materials where the magnetic ions exhibit a unique crystal field symmetry This
+finding translates in a sign-reversal between the average Fe magnetic orbital
+and spin moments. Large Fe-displacements, among some of the octahedral sites,
+lower the symmetry of the system producing anisotropic paths for the Fe-O
+bondings giving rise to a large orbital-lattice interaction akin to a
+preferential crystallographic direction for the magnetic orbital moment. The
+latter may lead to a partial re-orientation of the magnetic orbital moment
+under an external magnetic field that, combined to the ferrimagnetic nature of
+the GFO, can qualitatively explain the observed sign-reversal of the XMCD
+integral. The results suggest that a control over the local symmetry of the
+oxygen octahedra in transition metal oxides can offer a suitable leverage over
+the manipulation of the effective orbital and spin moments in magnetoelectric
+systems.",2102.12118v2
+2022-01-21,A Detailed Investigation of the Onion Structure of Exchanged Coupled Magnetic Fe(3-delta)O4@CoFe2O4@Fe(3-delta)O4 Nanoparticles,"Nanoparticles (NPs) which combine several magnetic phases offer wide
+perspectives for cutting edge applications because of the high modularity of
+their magnetic properties. Besides the addition of the magnetic characteristics
+intrinsic to each phase, the interface that results from core-shell and,
+further, from onion structures leads to synergistic properties such as magnetic
+exchange coupling. Such a phenomenon is of high interest to overcome the
+superparamagnetic limit of iron oxide NPs which hampers potential applications.
+In this manuscript, we report on the design of NPs with an onion-like structure
+which have been scarcely reported yet. These NPs consist in a Fe(3_delta)O4
+core covered by a first shell of CoFe2O4 and a second shell of Fe(3-delta)O4.
+They were synthesized by a multi-step seed mediated growth approach. Although
+TEM micrographs clearly show the growth of each shell from the iron oxide core,
+core sizes and shell thicknesses markedly differ from what is suggested by the
+size increase. We investigated very precisely the structure of NPs in
+performing high resolution (scanning) TEM imaging and GPA. The chemical
+composition and spatial distribution of atoms were studied by EELS. The
+chemical environment and oxidation state of cations were investigated by
+M\""ossbauer spectrometry, soft XAS and XMCD. These techniques allowed us to
+estimate the increase of Fe2+ content in the iron oxide core of the core@shell
+structure and the increase of the cobalt ferrite shell thickness in the
+core@shell@shell one, while the iron oxide shell appears to be much thinner
+than expected. Thus, the modification of the chemical composition as well as
+the size of the Fe(3-delta)O4 core and the thickness of the cobalt ferrite
+shell have a high impact on the magnetic properties. Furthermore, the growth of
+the iron oxide shell also markedly modifies the magnetic properties of the
+core-shell NPs.",2201.08923v1
+2001-08-20,Magnetic Field Scaling of the Conductance of Epitaxial Cuprate-Manganite Bilayers,"Conductance-voltage characteristics of epitaxial interfaces between oxide
+ferromagnets and oxide superconductors have been measured as a function of
+temperature and magnetic field. Their functional form is similar to that
+predicted by theories of transport across nearly transparent contacts between
+highly spin-polarized ferromagnets and d-wave superconductors. However, their
+magnetic field dependencies scale in striking and unusual ways, challenging our
+current understanding. Existing theories fail to account for apparent
+nonequilibium effects that are natural for spin injection in such geometries.",0108313v1
+2002-01-25,Magnetic Order in Transition Metal Oxides with Orbital Degrees of Freedom,"We investigate the frustrated magnetic interactions in cubic transition metal
+oxides with orbital degeneracy. The $e_g$ orbitals order easier and their
+ordering explains the $A$-type antiferromagnetic phase in KCuF$_3$ and
+LaMnO$_3$. In $t_{2g}$ systems the magnetic order changes at a transition from
+an orbital liquid to orbital ordered states. The fluctuations of $t_{2g}$
+orbitals play a prominent role in LaVO$_3$ and YVO$_3$, where they compete with
+the Jahn-Teller effect and trigger the C-type antiferromagnetic order.",0201455v1
+2004-09-10,Airy-function electron localization in the oxide superlattices,"Oxide superlattices and microstructures hold the promise for creating a new
+class of devices with unprecedented functionalities. Density-functional studies
+of the recently fabricated superlattices of lattice-matched perovskite
+titanates (SrTiO3)n/(LaTiO3)m reveal a classic wedge-shaped potential
+originating from the Coulomb potential of a charged sheet of La atoms. The
+potential in turn confines the electrons in the vicinity of the sheet, leading
+to an Airy-function localization of the electron states. Magnetism is
+suppressed for structures with a single LaTiO3 monolayer, while the bulk
+antiferromagnetism is recovered in the structures with a thicker LaTiO3, with a
+narrow transition region separating the magnetic LaTiO3 and the non-magnetic
+SrTiO3.",0409281v1
+2006-03-07,Theory of carrier mediated ferromagnetism in dilute magnetic oxides,"We analyze the origin of ferromagnetism as a result of carrier mediation in
+diluted magnetic oxide semiconductors in the light of the experimental evidence
+reported in the literature. We propose that a combination of percolation of
+magnetic polarons at lower temperature and Ruderman-Kittel-Kasuya-Yosida
+ferromagnetism at higher temperature may be the reason for the very high
+critical temperatures measured (up to ~700 K).",0603182v2
+2009-07-24,Unusual non-equilibrium behavior of cupric oxide nanoparticles,"We report studies on temperature, field and time dependence of magnetization
+on cupric oxide nanoparticles of sizes 9 nm, 13 nm and 16 nm. The nanoparticles
+show unusual features in comparison to other antiferromagnetic nanoparticle
+systems. The field cooled (FC) and zero field cooled (ZFC) magnetization curves
+bifurcate well above the Neel temperature and the usual peak in the ZFC
+magnetization curve is absent.
+  The system does not show any memory effects which is in sharp contrast to the
+usual behavior shown by other antiferromagnetic nanoparticles. It turns out
+that the nature of CuO nanoparticles is very strange and is neither
+superparamagnetic nor spin glass-like .",0907.4222v1
+2012-07-04,Evidence for Intra-Unit-Cell magnetic order in Bi2Sr2CaCu2O8+d,"Polarized elastic neutron scattering measurements have been performed in the
+bilayer copper oxide system Bi2Sr2CaCu2O8+d, providing evidence for an intra
+unit cell (IUC) magnetic order inside the pseudo-gap state. That shows time
+reversal symmetry breaking in that state as already reported in Bi2Sr2CaCu2O8+d
+through dichroism in circularly polarized photoemission experiments. The
+magnetic order displays the same characteristic features as the one previously
+reported for monolayer HgBa2CuO4+d and bilayer YBa2Cu3O6+x, demonstrating that
+this genuine phase is ubiquitous of the pseudo-gap of high temperature copper
+oxide materials.",1207.1038v1
+2017-04-20,Current-induced effective magnetic field in a half-metallic oxide La0.67Sr0.33MnO3,"We investigated current-induced effective magnetic field Heff in
+half-metallic oxide La0.67Sr0.33MnO3 (LSMO) films with various thicknesses by
+using the planar Hall effect. Applying in-plane current to the LSMO films
+exerted an in-plane Heff orthogonal to the current direction on magnetization.
+The Heff magnitude increased with increasing current magnitude, and the
+direction reversed when the applied current switched to opposite sign. Assuming
+that a 6.5-u.c. insulating layer is created in the LSMO, the values of Heff
+observed in devices with three different LSMO thicknesses were almost scaled
+with current density, evaluated from the effective LSMO thickness excluding the
+insulating layer, suggesting that Heff is induced in the LSMO bulk.",1704.05989v1
+2019-01-25,Polarized neutron reflectometry study from iron oxide nanoparticles monolayer,"We report on the polarized neutron reflectometry investigation of monolayer
+of magnetic iron oxide nanoparticles assembled by the Langmuir-Schaefer method.
+After deposition onto a solid substrate the polarized neutron reflectometry
+measurements in the external magnetic field were carried out. Thickness,
+density, roughness and in-depth resolved magnetization profile of the resulted
+layer were obtained from accurate fitting routine.",1901.08819v1
+2009-04-28,Magnetically-induced electric polarization in an organo-metallic magnet,"The coupling between magnetic order and ferroelectricity has been under
+intense investigation in a wide range of transition-metal oxides. The strongest
+coupling is obtained in so-called magnetically-induced multiferroics where
+ferroelectricity arises directly from magnetic order that breaks inversion
+symmetry. However, it has been difficult to find non-oxide based materials in
+which these effects occur. Here we present a study of copper dimethyl sulfoxide
+dichloride (CDC), an organo-metallic quantum magnet containing $S = 1/2$ Cu
+spins, in which electric polarization arises from non-collinear magnetic order.
+We show that the electric polarization can be switched in a stunning hysteretic
+fashion. Because the magnetic order in CDC is mediated by large organic
+molecules, our study shows that magnetoelectric interactions can exist in this
+important class of materials, opening the road to designing magnetoelectrics
+and multiferroics using large molecules as building blocks. Further, we
+demonstrate that CDC undergoes a magnetoelectric quantum phase transition where
+both ferroelectric and magnetic order emerge simultaneously as a function of
+magnetic field at very low temperatures.",0904.4490v1
+2020-06-01,High-throughput search for magnetic and topological order in transition metal oxides,"The discovery of intrinsic magnetic topological order in $\rm MnBi_2Te_4$ has
+invigorated the search for materials with coexisting magnetic and topological
+phases. These multi-order quantum materials are expected to exhibit new
+topological phases that can be tuned with magnetic fields, but the search for
+such materials is stymied by difficulties in predicting magnetic structure and
+stability. Here, we compute over 27,000 unique magnetic orderings for over
+3,000 transition metal oxides in the Materials Project database to determine
+their magnetic ground states and estimate their effective exchange parameters
+and critical temperatures. We perform a high-throughput band topology analysis
+of centrosymmetric magnetic materials, calculate topological invariants, and
+identify 18 new candidate ferromagnetic topological semimetals, axion
+insulators, and antiferromagnetic topological insulators. To accelerate future
+efforts, machine learning classifiers are trained to predict both magnetic
+ground states and magnetic topological order without requiring first-principles
+calculations.",2006.01075v1
+2007-12-12,Analysis of anisotropy crossover due to oxygen in Pt/Co/MOx trilayer,"Extraordinary Hall effect and X-ray spectroscopy measurements have been
+performed on a series of Pt/Co/MOx trilayers (M=Al, Mg, Ta...) in order to
+investigate the role of oxidation in the onset of perpendicular magnetic
+anisotropy at the Co/MOx interface. It is observed that varying the oxidation
+time modifies the magnetic properties of the Co layer, inducing a magnetic
+anisotropy crossover from in-plane to out-of-plane. We focused on the influence
+of plasma oxidation on Pt/Co/AlOx perpendicular magnetic anisotropy. The
+interfacial electronic structure is analyzed via X-ray photoelectron
+spectroscopy measurements. It is shown that the maximum of out-of-plane
+magnetic anisotropy corresponds to the appearance of a significant density of
+Co-O bondings at the Co/AlOx interface.",0712.1905v1
+2014-09-05,Magneto-ionic Control of Interfacial Magnetism,"In metal/oxide heterostructures, rich chemical, electronic, magnetic and
+mechanical properties can emerge from interfacial chemistry and structure. The
+possibility to dynamically control interface characteristics with an electric
+field paves the way towards voltage control of these properties in solid-state
+devices. Here we show that electrical switching of the interfacial oxidation
+state allows for voltage control of magnetic properties to an extent never
+before achieved through conventional magnetoelectric coupling mechanisms. We
+directly observe, for the first time, in situ voltage driven O$^{2-}$ migration
+in a Co/metal-oxide bilayer, which we use to toggle the interfacial magnetic
+anisotropy energy by >0.6 erg/cm$^2$. We exploit the thermally-activated nature
+of ion migration to dramatically increase the switching efficiency and to
+demonstrate reversible patterning of magnetic properties through local
+activation of ionic migration. These results suggest a path towards
+voltage-programmable materials based on solid-state switching of interface
+oxygen chemistry.",1409.1843v1
+2015-04-13,Evidence for Localized Moment Picture in Mn-based Heusler Compounds,"X-ray absorption spectroscopy (XAS) and X-ray magnetic circular dichroism
+(XMCD) were used to probe the oxidation state and element specific magnetic
+moments of Mn in Heusler compounds with different crystallographic structure.
+The results were compared with theoretical calculations, and it was found that
+in full Heusler alloys, Mn is metallic (oxidation state near 0) on both
+sublattices. The magnetic moment is large and localized when octahedrally
+coordinated by the main group element, consistent with previous theoretical
+work, and reduced when the main group coordination is tetrahedral. By contrast,
+in the half Heusler compounds the magnetic moment of the Mn atoms is large and
+the oxidation state is +1 or +2. The magnetic and electronic properties of Mn
+in full and half Heusler compounds are strongly dependent on the structure and
+sublattice, a fact that can be exploited to design new materials.",1504.03088v1
+2015-04-25,Magnetic phase transitions in Ta/CoFeB/MgO multilayers,"We study thin films and magnetic tunnel junction nanopillars based on
+Ta/Co$_{20}$Fe$_{60}$B$_{20}$/MgO multilayers by electrical transport and
+magnetometry measurements. These measurements suggest that an ultrathin
+magnetic oxide layer forms at the Co$_{20}$Fe$_{60}$B$_{20}$/MgO interface. At
+approximately 160 K, the oxide undergoes a phase transition from an insulating
+antiferromagnet at low temperatures to a conductive weak ferromagnet at high
+temperatures. This interfacial magnetic oxide is expected to have significant
+impact on the magnetic properties of CoFeB-based multilayers used in spin
+torque memories.",1504.06716v1
+2010-05-31,Magnetism in graphite oxide: The role of epoxy groups,"We investigate the magnetism in graphite by controlled oxidation. Our
+approach renders graphite an insulator while maintaining its structure. Fourier
+transform infrared spectroscopy and X-ray absorption near edge structure
+spectra reveal that graphite oxide has epoxy groups on its surface and it is
+not thermally stable. Magnetic susceptibility data exhibit negative Curie
+temperature, field irreversibility, and slow relaxation. The magnetic
+properties diminish after the epoxy groups are destroyed. The overall results
+indicate the unexpected magnetism is associated with the presence of epoxy
+groups.",1005.5580v2
+2016-05-09,Self-heating effects of the surface oxidized FeCo nanoparticles colloid under alternating magnetic field,"To evaluate the self-heating effects of FeCo magnetic nanoparticles, the
+surface oxidized FeCo nanoparticles were synthesized by co-precipitation method
+with the reduction reaction without any post treatments. As-synthesized FeCo
+nanoparticles exhibited the mean diameter of about 39 nm with the oxidized
+shell thickness of about 4-5 nm. The saturation magnetization and coercivity
+were obtained 172 emu/g and 268 Oe at 300 K, respectively. The heat elevation
+of the FeCo magnetic colloid was measured under alternating magnetic fields of
+76, 102, and 127 Oe with selectable frequencies of 190, 250 and 355 kHz. The
+heat temperature increased up to about 45 oC from initial temperature of 24 oC
+under 127 Oe and 355 kHz, which the specific absorption exhibited about 35.7
+W/g.",1605.02806v1
+2017-06-07,Monte Carlo study of the exchange bias effect in Co/CoO core-shell nanowires,"We study the magnetic properties of cylindrical ferromagnetic core -
+antiferromagnetic shell nanowires using Monte Carlo simulations and a classical
+Heisenberg Hamiltonian in order to elucidate the impact of the oxidized shell
+on the magnetic properties and the magnetization reversal mechanism. We find
+that the coupling to the antiferromagnetic shell leads to suppression of the
+coercivity and emergence of a weak exchange bias effect. Comparison of the
+magnetization reversal mechanism in the bare and the surface-oxidized nanowire
+reveals that the domain wall propagation and annihilation remains the dominant
+reversal mechanism in surface oxidized nanowires as in their ferromagnetic
+counterparts. However, the interface exchange coupling introduces a secondary
+reversal mechanism activated in the central part of the wire with
+characteristics of coherent rotation, which acts in synergy to wall propagation
+leading to enhancement of the wall mobility. This effect is more pronounced in
+nanowires with large exchange bias values and is attributed to the
+uncompensated interface moments that act as nucleation centers for
+magnetization reversal. Our results are in good agreement with recent
+measurements in Co and Co/CoO nanowires.",1706.02395v1
+2020-02-27,Second Harmonic Generation of cuprous oxide in magnetic fields,"Recently Second Harmonic Generation (SHG) for the yellow exciton series in
+cuprous oxide has been demonstrated [J. Mund et al., Phys. Rev. B 98, 085203
+(2018)]. Assuming perfect $O_{\mathrm{h}}$ symmetry, SHG is forbidden along
+certain high-symmetry axes. Perturbations can break this symmetry and forbidden
+transitions may become allowed. We investigate theoretically the effect of
+external magnetic fields on the yellow exciton lines of cuprous oxide. We
+identify two mechanisms by which an applied magnetic field can induce a second
+harmonic signal in a forbidden direction. First of all, a magnetic field by
+itself generally lifts the selection rules. In the Voigt configuration, an
+additional magneto-Stark electric field appears. This also induces certain SHG
+processes differing from those induced by the magnetic field alone.
+Complementary to the manuscript by A. Farenbruch et al. [Phys. Rev. B,
+submitted], we perform a full numerical diagonalization of the exciton
+Hamiltonian including the complex valence band structure. Numerical results are
+compared with experimental data.",2002.12064v1
+2017-09-21,Current-induced magnetization switching using electrically-insulating spin-torque generator,"Current-induced magnetization switching through spin-orbit torques (SOTs) is
+the fundamental building block of spin-orbitronics. The SOTs generally arise
+from the spin-orbit coupling of heavy metals. However, even in a
+heterostructure where a metallic magnet is sandwiched by two different
+insulators, a nonzero current-induced SOT is expected because of the broken
+inversion symmetry; an electrical insulator can be a spin-torque generator.
+Here, we demonstrate current-induced magnetization switching using an
+insulator. We show that oxygen incorporation into the most widely used
+spintronic material, Pt, turns the heavy metal into an electrically-insulating
+generator of the SOTs, enabling the electrical switching of perpendicular
+magnetization in a ferrimagnet sandwiched by electrically-insulating oxides. We
+further found that the SOTs generated from the Pt oxide can be controlled
+electrically through voltage-driven oxygen migration. These findings open a
+route towards energy-efficient, voltage-programmable spin-orbit devices based
+on solid-state switching of heavy metal oxidation.",1709.07127v1
+2023-02-06,Observation of Coherently Coupled Cation Spin Dynamics in an Insulating Ferrimagnetic Oxide,"Many technologically useful magnetic oxides are ferrimagnetic insulators,
+which consist of chemically distinct cations. Here, we examine the spin
+dynamics of different magnetic cations in ferrimagnetic NiZnAl-ferrite
+(Ni$_{0.65}$Zn$_{0.35}$Al$_{0.8}$Fe$_{1.2}$O$_4$) under continuous microwave
+excitation. Specifically, we employ time-resolved x-ray ferromagnetic resonance
+to separately probe Fe$^{2+/3+}$ and Ni$^{2+}$ cations on different sublattice
+sites. Our results show that the precessing cation moments retain a rigid,
+collinear configuration to within $\approx$2$^\circ$. Moreover, the effective
+spin relaxation is identical to within $<$10% for all magnetic cations in the
+ferrite. We thus validate the oft-assumed ``ferromagnetic-like'' dynamics in
+resonantly driven ferrimagnetic oxides, where the magnetic moments from
+different cations precess as a coherent, collective magnetization.",2302.03100v1
+2024-03-08,Design of Magnetic Polar Double-Double Perovskite Oxides through Cation Ordering,"Commencing from the centrosymmetric MnRMnSbO$_6$ compound, we explore the
+realm of magnetic polar double-double perovskite oxides characterized by
+significant ferroelectric polarization. Employing symmetry operations,
+first-principles methodologies, and Monte Carlo simulations, our investigation
+delves into the structural, magnetic, ferroelectric, and electronic attributes
+of the polar LaFeMnNiO$_6$ and LaTiMnNiO$_6$ compounds. The structural analysis
+uncovers that the paraelectric-ferroelectric phase transition is intricately
+linked to the Fe/Ti-displacement of square planar Fe/TiO$_4$. Notably, the
+magnetic LaFeMnNiO$_6$ and LaTiMnNiO$_6$ compounds demonstrate robust
+ferroelectric polarizations, measuring 20.0 $\mu$C/cm$^2$ and 21.8
+$\mu$C/cm$^2$, respectively, accompanied by minimalist forbidden energy gaps of
+1.40 eV and 1.18 eV using the GGA+U method. Furthermore, we pinpoint elevated
+magnetic transition temperatures for these compounds. Additionally, our study
+scrutinizes the energies associated with diverse spin configurations and
+identifies potential minimum decomposition pathways into stable oxides. This
+comprehensive analysis ensures the meticulous formation of the LaFeMnNiO$_6$
+and LaTiMnNiO$_6$ compounds.",2403.05498v1
+2023-03-28,Hole doping in compositionally complex correlated oxide enables tunable exchange biasing,"Magnetic interfaces and the phenomena arising from them drive both the design
+of modern spintronics and fundamental research. Recently, it was revealed that
+through designing magnetic frustration in configurationally complex entropy
+stabilized oxides, exchange bias can occur in structurally single crystal
+films. This eliminates the need for complex heterostructures and nanocomposites
+in the design and control of magnetic response phenomena. In this work, we
+demonstrate through hole doping of a high entropy perovskite oxide that tuning
+of magnetic responses can be achieved. With detailed magnetometry, we show
+magnetic coupling exhibiting a variety of magnetic responses including exchange
+bias and antiferromagnetic spin reversal in the entropy stabilized ABO3
+perovskite oxide La1-xSrx(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 family. We find that
+manipulation of the A-site charge state can be used to balance magnetic phase
+compositions and coupling responses. This allows for the creation of highly
+tunable exchange bias responses. In the low Sr doping regime, a spin frustrated
+region arising at the antiferromagnetic phase boundary is shown to directly
+couple to the antiferromagnetic moments of the film and emerges as the dominant
+mechanism, leading to a vertical shift of magnetization loops in response to
+field biasing. At higher concentrations, direct coupling of antiferromagnetic
+and ferromagnetic regions is observed. This tunability of magnetic coupling is
+discussed within the context of these three competing magnetic phases,
+revealing critical features in designing exchange bias through exploiting spin
+frustration and disorder in high entropy oxides.",2303.15922v1
+2014-11-17,Oscillatory Non-collinear Magnetism Induced by Interfacial Charge Transfer in Metallic Oxide Superlattices,"Interfaces between correlated complex oxides are promising avenues to realize
+new forms of magnetism that arise as a result of charge transfer, proximity
+effects and locally broken symmetries. We report upon the discovery of a
+non-collinear magnetic structure in superlattices of the ferromagnetic metallic
+oxide La2/3Sr1/3MnO3 (LSMO) and the correlated metal LaNiO3 (LNO). The exchange
+interaction between LSMO layers is mediated by the intervening LNO, such that
+the angle between the magnetization of neighboring LSMO layers varies in an
+oscillatory manner with the thickness of the LNO layer. The magnetic field,
+temperature, and spacer thickness dependence of the non-collinear structure are
+inconsistent with the bilinear and biquadratic interactions that are used to
+model the magnetic structure in conventional metallic multilayers. A model that
+couples the LSMO layers to a helical spin state within the LNO fits the
+observed behavior. We propose that the spin-helix results from the interaction
+between a spatially varying spin susceptibility within the LNO and interfacial
+charge transfer that creates localized Ni2+ states. This provides a new
+approach to engineering non-collinear spin textures in metallic oxide
+heterostructures that can be exploited in devices based on both spin and charge
+transport.",1411.4344v1
+2015-03-03,Tunable room-temperature ferromagnet using an iron-oxide and graphene oxide nanocomposite,"Magnetic materials have found wide application ranging from electronics and
+memories to medicine. Essential to these advances is the control of the
+magnetic order. To date, most room-temperature applications have a fixed
+magnetic moment whose orientation is manipulated for functionality. Here we
+demonstrate an iron-oxide and graphene oxide nanocomposite based device that
+acts as a tunable ferromagnet at room temperature. Not only can we tune its
+transition temperature in a wide range of temperatures around room temperature,
+but the magnetization can also be tuned from zero to 0.011 A.m$^2$/kg through
+an initialization process with two readily accessible knobs (magnetic field and
+electric current), after which the system retains its magnetic properties
+semi-permanently until the next initialization process. We construct a
+theoretical model to illustrate that this tunability originates from an
+indirect exchange interaction mediated by spin-imbalanced electrons inside the
+nanocomposite.",1503.00960v1
+2023-03-12,Competing Magnetic Interactions and Field-Induced Metamagnetic Transition in Highly Crystalline Phase-Tunable Iron Oxide Nanorods,"The inherent existence of multi phases in iron oxide nanostructures
+highlights the significance of them being investigated deliberately to
+understand and possibly control the phases. Here, the effects of annealing at
+250 0C with a variable duration on the bulk magnetic and structural properties
+of high aspect ratio bi-phase iron oxide nanorods with ferrimagnetic Fe3O4 and
+antiferromagnetic alpha-Fe2O3 is explored. Increasing annealing time under a
+free flow of oxygen enhanced the alpha-Fe2O3 volume fraction, and improved the
+crystallinity of the Fe3O4 phase, identified in changes in the magnetization as
+a function of annealing time. A critical annealing time of approximately 3
+hours maximized the presence of both phases, as observed via an enhancement in
+the magnetization and an interfacial pinning effect. This is attributed to
+disordered spins separating the magnetically distinct phases which tend to
+align with the application of a magnetic field at high temperatures. The
+increased antiferromagnetic phase can be distinguished due to the field-induced
+metamagnetic transitions observed in structures annealed for more than 3 hours
+and was especially prominent in the 9-hour annealed sample. Our controlled
+study in determining the changes in volume fractions with annealing time will
+enable precise control over phase tunability in iron oxide nanorods, allowing
+custom-made phase volume fractions in different applications ranging from
+spintronics to biomedical applications.",2303.06684v1
+2002-07-27,The Hydride Anion in an Extended Transition Metal Oxide Array: LaSrCoO_3H_{0.7},"We present the synthesis and structural characterisation of a transition
+metal oxide hydride, LaSrCoO_3H_{0.7}, which adopts an unprecedented structure
+in which oxide chains are bridged by hydride anions to form a two- dimensional
+extended network. The metal centers are strongly coupled by their bonding with
+both oxide and hydride ligands to produce magnetic ordering up to at least 350
+K. The synthetic route is sufficiently general to allow the prediction of a new
+class of transition metal-containing electronic and magnetic materials.",0207660v1
+2013-07-24,Sr and Mn co-doped LaCuSO: A wide band gap oxide diluted magnetic semiconductor with TC around 200K,"Here we report the synthesis of a bulk oxide diluted magnetic semiconductor
+(DMS) system La1-xSrxCu0.925Mn0.075SO (x=0, 0.025, 0.05, 0.075, and 0.1). As a
+wide band gap p-type oxide semiconductor, LaCuSO satisfies all the conditions
+forecasted theoretically to be a room temperature DMS. The Curie temperature
+(TC) is around 200K as x>0.05, which is among the highest TC record of known
+bulk DMS materials up to now. The system provides a rare example of oxide DMS
+system with p-type conduction, which is important for formation of high
+temperature spintronic devices.",1307.6311v1
+2014-05-19,Multiferroic Iron Oxide Thin Films at Room-Temperature,"In spite of being highly relevant for the development of a new generation of
+information storage devices, not many single-phase materials displaying
+magnetic and ferroelectric orders above room temperature are known. Moreover,
+these uncommon materials typically display insignificant values of the remanent
+moment in one of the ferroic orders or are complex multicomponent oxides which
+will be very challenging to integrate in devices. Here we report on the
+strategy to stabilize the metastable epsilon-Fe2O3 in thin film form, and we
+show that besides its already known ferrimagnetic nature, the films are also
+ferroelectric at 300 K with a remanent polarization of 1 microC/cm2. The film
+polarization shows long retention times and can be switched under small applied
+voltages. These characteristics make of epsilon-Fe2O3 the first single-ion
+transition-metal oxide which is ferro(ferri)magnetic and ferroelectric at room
+temperature. The simple composition of this new multiferroic oxide and the
+discovery of a robust path for its thin film growth may boost the exploitation
+of epsilon-Fe2O3 in novel devices.",1405.4909v1
+2020-01-02,Origin of Strong Two-Magnon Scattering in Heavy Metal/Ferromagnet/Oxide Heterostructures,"We experimentally investigate the origin of the two-magnon scattering (TMS)
+in heavy-metal (HM)/ferromagnet (FM)/oxide heterostructures (FM = Co, Ni81Fe19,
+or Fe60Co20B20) by varying the materials located above and below the FM layers.
+We show that strong TMS in HM/FM/oxide systems arises primarily at the HM/FM
+interface and increases with the strength of interfacial spin-orbit coupling
+and magnetic roughness at this interface. TMS at the FM/oxide interface is
+relatively weak, even in systems where spin-orbit coupling at this interface
+generates strong interfacial magnetic anisotropy. We also suggest that the
+spin-current-induced excitation of non-uniform short-wavelength magnon at the
+HM/FM interface may function as a mechanism of spin memory loss for the
+spin-orbit torque exerted on the uniform mode.",2001.00300v1
+2020-06-10,Hexagonal Perovskites as Quantum Materials,"Hexagonal oxide perovskites, in contrast to the more familiar perovskites,
+allow for face-sharing of metal-oxygen octahedra or trigonal prisms within
+their structural frameworks. This results in dimers, trimers, tetramers, or
+longer fragments of chains of face-sharing octahedra in the crystal structures,
+and consequently in much shorter metal-metal distances and lower
+metal-oxygen-metal bond angles than are seen in the more familiar perovskites.
+The presence of the face-sharing octahedra can have a dramatic impact on
+magnetic properties of these compounds, and dimer-based materials, in
+particular, have been the subjects of many quantum-materials-directed studies
+in materials physics. Hexagonal oxide perovskites are of contemporary interest
+due to their potential for geometrical frustration of the ordering of magnetic
+moments or orbital occupancies at low temperatures, which is especially
+relevant to their significance as quantum materials. As such, several hexagonal
+oxide perovskites have been identified as potential candidates for hosting the
+quantum spin liquid state at low temperatures. In our view, hexagonal oxide
+perovskites are fertile ground for finding new quantum materials. This review
+briefly describes the solid state chemistry of many of these materials.",2006.05864v1
+2020-10-25,Multifunctional Oxides for Topological Magnetic Textures by Design,"Several challenges in designing an operational Skyrmion racetrack memory are
+well-known. Among those challenges, a few contradictions can be identified if
+researchers were to rely only on metallic materials. Hence, expanding the
+exploration on Skyrmion Physics into oxide materials is essential to bridge the
+contradicting gap. In this topical review, we first briefly revise the theories
+and criteria involved in stabilizing and manipulating Skymions, followed by
+studying the behaviors of dipolar-stabilized magnetic bubbles. Next, we explore
+the properties of multiferroic Skyrmions with magnetoelectric coupling, which
+can only be stabilized in Cu$_2$OSeO$_3$ thus far, as well as the rare bulk
+N\'eel-type Skyrmions in some polar materials. As an interlude section, we
+review the theory of Anomalous (AHE) and Topological Hall Effect (THE), before
+going through the recent progress of THE in oxide thin films. The debate about
+an alternative interpretation is also discussed. Finally, this review ends with
+future outlooks about the promising strategies of using interfacial
+charge-transfer and (111)-orientation of perovskites to benefit the field of
+Skyrmion research.",2010.13012v1
+2015-05-13,Optical detection of magnetic orders in HgCr$_2$O$_4$ frustrated spin magnet under pulsed high magnetic fields,"A magneto-optical survey was conducted for HgCr$_2$O$_4$ powder samples under
+pulsed high magnetic fields of up to 55 T. Intensity changes in magnetic fields
+observed for the exciton-magnon-phonon optical transition spectra coincide well
+with those of magnetization, lattice distortion from X-ray diffraction, and
+electron-magnetic resonances. The last-ordered phase was detected prior to the
+fully polarized magnetic phase, similarly to the other chromium spinel oxide,
+ZnCr$_2$O$_4$ and CdCr$_2$O$_4$.",1505.03216v1
+2019-04-16,Oxidation annealing effects on the spin-glass-like magnetism and appearance of superconductivity in T*-type La$_{1-x/2}$Eu$_{1-x/2}$Sr$_x$CuO$_4$ (0.14 $\leq x \leq$ 0.28),"We investigated the magnetism and superconductivity in as-sintered (AS) and
+oxidation annealed (OA) T*-type La$_{1-x/2}$Eu$_{1-x/2}$Sr$_x$CuO$_4$ (LESCO)
+with 0.14 $\leq x \leq$ 0.28 by the first comprehensive muon spin
+rotation/relaxation ($\mu$SR), magnetic susceptibility, and electrical
+resistivity measurements. In OA superconducting samples, no evidence of
+magnetic order was observed, whereas AS semiconducting samples exhibited
+evidence of a disordered magnetic state in the measured temperature range
+between $\sim$4 K and $\sim$8 K. Therefore, the ground state in LESCO
+drastically varies with oxidation annealing and the magnetic phase
+competitively exists with the superconducting (SC) phase. The magnetic phase in
+the AS LESCO is quite robust against Sr doping, while the SC phase degrades
+with increasing $x$. A monotonous decrease of the SC transition temperature
+from 24.5 K in $x$ = 0.14 to 9.0 K in $x$ = 0.28 suggests the disappearance of
+the SC phase at $x$ $\sim$ 0.34. Furthermore, we clarified the simultaneous
+development of (quasi) static magnetism and the electrical resistivity at a low
+temperature in AS samples, suggesting the inducement of magnetism by the
+suppression of carrier mobility. The variation in magnetism due to annealing is
+discussed from a viewpoint of structural defects, which was previously reported
+from neutron diffraction measurements.",1904.07541v2
+2011-01-17,Modeling the iron oxides and oxyhydroxides for the prediction of environmentally sensitive phase transformations,"Iron oxides and oxyhydroxides are challenging to model computationally as
+competing phases may differ in formation energies by only several kJ/mol, they
+undergo magnetization transitions with temperature, their structures may
+contain partially occupied sites or long-range ordering of vacancies, and some
+loose structures require proper description of weak interactions such as
+hydrogen bonding and dispersive forces. If structures and transformations are
+to be reliably predicted under different chemical conditions, each of these
+challenges must be overcome simultaneously, while preserving a high level of
+numerical accuracy and physical sophistication. Here we present comparative
+studies of structure, magnetization, and elasticity properties of iron oxides
+and oxyhydroxides using density functional theory calculations with plane-wave
+and locally-confined-atomic-orbital basis sets, which are implemented in VASP
+and SIESTA packages, respectively. We have selected hematite, maghemite,
+goethite, lepidocrocite, and magnetite as model systems from a total of 13
+known iron oxides and oxyhydroxides; and use same convergence criteria and
+almost equivalent settings in order to make consistent comparisons. Our results
+show both basis sets can reproduce the energetic stability and magnetic
+ordering, and are in agreement with experimental observations. There are
+advantages to choosing one basis set over the other, depending on the intended
+focus. In our case, we find the method using PW basis set most appropriate, and
+combine our results to construct the first phase diagram of iron oxides and
+oxyhydroxides in the space of competing chemical potentials, generated entirely
+from first principles",1101.3105v1
+2015-04-22,Detection of defect-induced magnetism in low-dimensional ZnO structures by Magnetophotocurrent,"The detection of defect-induced magnetic order in single low-dimensional
+oxide structures is in general difficult because of the relatively small yield
+of magnetically ordered regions. In this work we have studied the effect of an
+external magnetic field on the transient photocurrent measured after light
+irradiation on different ZnO samples at room temperature. We found that a
+magnetic field produces a change in the relaxation rate of the transient
+photocurrent only in magnetically ordered ZnO samples. This rate can decrease
+or increase with field depending whether the magnetic order region is in the
+bulk or only at the surface of the ZnO sample. The phenomenon reported here is
+of importance for the development of magneto-optical low-dimensional oxides
+devices and provide a new guideline for the detection of magnetic order in
+low-dimensional magnetic semiconductors.",1504.05828v1
+2019-04-24,Ultra-low-power orbital-controlled magnetization switching using a ferromagnetic oxide interface,"A major challenge in spin-based electronics is reducing power consumption for
+magnetization switching of ferromagnets, which is being implemented by
+injecting a large spin-polarized current. The alternative approach is to
+control the magnetic anisotropy (MA) of the ferromagnet by an electric field.
+However, the voltage-induced MA is too weak to deterministically switch the
+magnetization without an assisting magnetic field, and the strategy towards
+this goal remains elusive. Here, we demonstrate a new scheme of
+orbital-controlled magnetization switching (OCMS): A sharp change in the MA is
+induced when the Fermi level is moved between energy bands with different
+orbital symmetries. Using a ferromagnetic oxide interface, we show that OCMS
+can be used to achieve a deterministic and magnetic-field-free 90
+degree-magnetization switching solely by applying an extremely small electric
+field of 0.05 V/nm with a negligibly small current density of 10^-2 A/cm^2. Our
+results highlight the huge potential of band engineering in ferromagnetic
+materials for efficient magnetization control.",1904.10599v1
+2021-11-06,Phase transition in the 5d1 double perovskite Ba2CaReO6 induced by high magnetic field,"Magnetic properties of an antiferromagnetic double perovskite oxide
+Ba2CaReO6, where Re6+ (5d1) ions with large spin-orbit coupling are arranged on
+the face-centered-cubic lattice, are investigated using pulsed high magnetic
+field up to 66 T. Magnetization and magnetostriction measurements have revealed
+a magnetic field induced phase transition at around 50 T. The phase transition
+accompanies a jump of magnetization and longitudinal magnetostriction of
+approximately 2 10^(-4) with the change of power law behavior, indicating
+sizable coupling between the electronic degrees of freedom and the lattice. The
+high field phase exhibits a magnetic moment approximately 0.2 {\mu}B, which is
+close to the values observed in 5d1 double perovskite oxides with non-collinear
+magnetic structure. We argue that Ba2CaReO6 is an antiferromagnet that sits
+close to the phase boundary between the collinear and non-collinear phases,
+providing the target material for investigating the interplay between
+spin-orbital entangled electrons and magnetic field.",2111.03807v1
+2022-02-15,Optically-induced magnetization switching in NiCo2O4 thin films using ultrafast lasers,"Recently, all-optical magnetization control has been garnering considerable
+attention in realizing next-generation ultrafast magnetic information devices.
+Here, employing a magneto-optical Kerr effect (MOKE) microscope, we observed
+the laser-induced magnetization switching of ferrimagnetic oxide NiCo2O4 (NCO)
+epitaxial thin films with perpendicular magnetic anisotropy, where the sample
+was pumped at 1030-nm laser pulses, and magnetic domain images were acquired
+via the MOKE microscope with a white light emitting diode. Laser pulses
+irradiated an NCO thin film at various temperatures from 300 K to 400 K while
+altering the parameters of pulse interval, fluence, and the number of pulses
+with the absence of the external magnetic field. We observed accumulative
+all-optical switching at 380 K and above. Our observation of oxide NCO thin
+films facilitates the realization of chemically stable magnetization switching
+using ultrafast lasers, and without applying a magnetic field.",2202.07257v1
+2023-09-11,Magnetic anisotropy driven by ligand in 4d transition metal oxide SrRuO3,"The origin of magnetic anisotropy in magnetic compounds is a longstanding
+issue in solid state physics and nonmagnetic ligand ions are considered to
+contribute little to magnetic anisotropy. Here, we introduce the concept of
+ligand driven magnetic anisotropy in a complex transition-metal oxide. We
+conducted X ray absorption and X ray magnetic circular dichroism spectroscopies
+at the Ru and O edges in the 4d ferromagnetic metal SrRuO3. Systematic
+variation of the sample thickness in the range below 10 nm allowed us to
+control the localization of Ru 4d t2g states, which affects the magnetic
+coupling between the Ru and O ions. We found that the orbital magnetization of
+the ligand induced via hybridization with the Ru 4d orbital determines the
+magnetic anisotropy in SrRuO3.",2309.05228v2
+2020-04-07,Structural Transition in Oxidized Ca$_2$N Electrenes: CaO/CaN 2D heterostructures,"Based on first-principles calculations we show that the oxidation of
+ultrathin films of Ca$_2$N electrides, electrenes, drives a
+hexagonal$\rightarrow$tetragonal structural transition. The ground state
+configuration of the oxidized monolayer (ML) and bilayer (BL) systems can be
+viewed as CaO/CaN and CaO/(CaN)$_2$/CaO two dimensional (2D) heterostructures.
+In both systems, we found nearly free electron (NFE) states lying near the
+vacuum level, and the spatial projection reveals that they are localized above
+the oxidized CaO surface. Focusing on the magnetic properties, we find that the
+nitrogen atoms of the oxidized Ca$_2$N becomes spin-polarized ($\sim$1
+$\mu_{\rm B}$/N-atom); where (i) the ferromagnetic and the anti-ferromagnetic
+phases are nearly degenerated in the ML system, CaO/CaN, while (ii) there is an
+energetic preference for the ferromagnetic phase in CaO/(CaN)$_2$/CaO. We show
+that such a FM preference can be strengthened upon mechanical compression.
+Further electronic structure calculations reveal that the FM CaO/Ca$_2$N/CaO
+presents half-metallicity, where the metallic channels project (predominantly)
+on the N-$2p_{x,y}$ orbitals. In addition to the total energy results,
+molecular dynamic and phonon spectra calculations have been done in order to
+verify its thermal and structural stabilities. Those findings suggest that
+CaO/Ca$_2$N/CaO is a quite interesting, and structurally stable, 2D FM
+heterostructure characterized half-metallic bands sandwiched by NFE states
+lying on the oxidized surfaces.",2004.03528v2
+2016-09-10,Induced ferromagnetic moment at the interface between epitaxial SrRuO$_3$ film and Sr$_2$RuO$_4$ single crystal,"SrRuO$_3$ (SRO113) is an important material for device physics particularly
+as one of the best metallic oxide electrodes for ferroelectric devices. This
+oxide has moderate electron correlations with novel properties including
+ferromagnetic ordering, which can be utilized in future to spintronics and
+superconducting spintronics devices. Recently, we observed strongly enhanced
+magnetization of SRO113 thin films grown on single crystals of the spin-triplet
+superconductor Sr$_2$RuO$_4$ (SRO214). To clarify the origin of such an
+enhancement, we conducted systematic investigations of magnetic properties of
+SRO113 films deposited on a variety of oxide substrates. We carefully
+subtracted the substrate contributions and found that the enhanced 2
+magnetization occurs only for SRO113/SRO214 films. We further found that
+neither strain nor metallicity of the substrate plays any significant roles in
+the enhancement. The X-ray magnetic circular dichroism reveals that the
+substrate-induced strain does not switch the Ru4+ state from the low-spin to
+high-spin states. The film-thickness dependence of the magnetization of
+SRO113/SRO214 films strongly suggest that the additional magnetization arises
+due to the induction of magnetic moment into the SRO214 substrate over 20-nm
+depth. Our results imply new magnetic functionality that can trigger studies
+searching for yet unknown physical phenomena in magnetic ruthenates.",1609.03010v1
+2022-05-23,Surface-Driven Evolution of the Anomalous Hall Effect in Magnetic Topological Insulator MnBi2Te4 Thin Films,"Understanding the effects of interfacial modification to the functional
+properties of magnetic topological insulator thin films is crucial for
+developing novel technological applications from spintronics to quantum
+computing. Here, we report that a large electronic and magnetic response is
+induced in the intrinsic magnetic topological insulator MnBi2Te4 by controlling
+the propagation of surface oxidation. We show that the formation of the surface
+oxide layer is confined to the top 1-2 unit cells but drives large changes in
+the overall magnetic response. Specifically, we observe a dramatic reversal of
+the sign of the anomalous Hall effect driven by finite thickness magnetism,
+which indicates that the film splits into distinct magnetic layers each with a
+unique electronic signature. These data reveal a delicate dependence of the
+overall magnetic and electronic response of MnBi2Te4 on the stoichiometry of
+the top layers. Our study suggests that perturbations resulting from surface
+oxidation may play a non-trivial role in the stabilization of the quantum
+anomalous Hall effect in this system and that understanding targeted
+modifications to the surface may open new routes for engineering novel
+topological and magnetic responses in this fascinating material.",2205.10991v1
+2014-02-04,A polarity-induced defect mechanism for conductivity and magnetism at polar-nonpolar oxide interfaces,"The discovery of conducting two-dimensional electron gas (2DEG) and magnetism
+at the interface between insulating nonmagnetic oxides, as exemplified by the
+polar LaAlO3 and nonpolar SrTiO3 has raised prospects for attaining interfacial
+functionalities absent in the component materials. Yet, the microscopic origin
+of such emergent phenomena remains unclear, posing obstacles to design of
+improved functionalities. Using first principles defect calculations, we reveal
+a unifying polarity-induced defect mechanism for both conductivity and
+magnetism at polar-nonpolar interfaces of nonmagnetic insulating oxides. We
+demonstrate that the polar-discontinuity across the interface triggers
+thermodynamically the spontaneous formation of certain defects that in turn
+cancel the polar field induced by the polar discontinuity. It turns out that
+the 2DEG originates from those spontaneously formed surface donor defects
+(oxygen vacancy), but the density of 2DEG is controlled by the interfacial
+anti-site acceptor defects (Al-on-Ti). The interface magnetism is found to
+originate from the un-ionized deep Ti-on-Al anti-site donor defects within the
+LaAlO3 side near the interface. Our results suggest practical design guidelines
+for inducing and controlling both 2DEG and magnetism at polar-nonpolar oxide
+interfaces.",1402.0895v3
+2020-05-07,Effect of interfacial oxidation layer in spin pumping experiments on Ni$_{80}$Fe$_{20}$/SrIrO$_3$ heterostructures,"SrIrO$_3$ with its large spin-orbit coupling and low charge conductivity has
+emerged as a potential candidate for efficient spin-orbit torque magnetization
+control in spintronic devices. We here report on the influence of an
+interfacial oxide layer on spin pumping experiments in Ni$_{80}$Fe$_{20}$
+(NiFe)/SrIrO$_3$ bilayer heterostructures. To investigate this scenario we have
+carried out broadband ferromagnetic resonance (BBFMR) measurements, which
+indicate the presence of an interfacial antiferromagnetic oxide layer. We
+performed in-plane BBFMR experiments at cryogenic temperatures, which allowed
+us to simultaneously study dynamic spin pumping properties (Gilbert damping)
+and static magnetic properties (such as the effective magnetization and
+magnetic anisotropy). The results for NiFe/SrIrO$_3$ bilayer thin films were
+analyzed and compared to those from a NiFe/NbN/SrIrO$_3$ trilayer reference
+sample, where a spin-transparent, ultra-thin NbN layer was inserted to prevent
+oxidation of NiFe. At low temperatures, we observe substantial differences in
+the magnetization dynamics parameters of these samples, which can be explained
+by an antiferromagnetic interfacial layer in the NiFe/SrIrO$_3$ bilayers.",2005.03727v1
+2002-06-06,Current-driven magnetization decrease in single crystalline ferromagnetic manganese oxide,"The electrical and magnetic response to a bias current has been investigated
+in a singlecrystalline ferromagnetic manganese oxide
+$\Pr_{0.8}$Ca$_{0.2}$MnO$_3$ . A significant decrease of the magnetization is
+observed at the same threshold current where a non-linearity of V-I
+characteristics appears. Such a behavior cannot be understood in the framework
+of the filamentary picture usually invoked for the non linearity of the other
+manganese oxides. Instead, an analogy with spintronic features might be useful
+and experimental signatures seem to be in agreement with excitations of spin
+waves by an electric current. This provides an example of a bulk system in
+which the spin polarized current induces a macroscopic change in the
+magnetization.",0206073v1
+2004-12-14,Nuclear Magnetic Resonance as a probe of nanometre-size orbital textures in magnetic transition metal oxides,"The study of strong electron correlations in transition metal oxides with
+modern microscopy and diffraction techniques unveiled a fascinating world of
+nanosize textures in the spin, charge, and crystal structure. Examples range
+from high $T_c$ superconducting cuprates and nickelates, to hole doped
+manganites and cobaltites. However, in many cases the appearance of these
+textures is accompanied with ""glassiness"" and multiscale/multiphase effects,
+which complicate significantly their experimental verification. Here, we
+demonstrate how nuclear magnetic resonance may be uniquely used to probe
+nanosize orbital textures in magnetic transition metal oxides. As a convincing
+example we show for the first time the detection of nanoscale orbital phase
+separation in the ground state of the ferromagnetic insulator
+La$_{0.875}$Sr$_{0.125}$MnO$_3$.",0412371v1
+2010-11-22,Orbital occupation and magnetic moments of tetrahedrally coordinated iron in CaBaFe4O7,"CaBaFe4O7 is a mixed-valent transition metal oxide having both Fe2+ and Fe3+
+ions in tetrahedral coordination. Here we characterize its magnetic properties
+by magnetization measurements and investigate its local electronic structure
+using soft x-ray absorption spectroscopy at the Fe L2,3 edges, in combination
+with multiplet cluster and spin-resolved band structure calculations. We found
+that the Fe2+ ion in the unusual tetrahedral coordination is Jahn-Teller active
+with the high-spin e^2 (up) t2^3 (up) e^1 (down) configuration having a
+x^2-y^2-like electron for the minority spin. We deduce that there is an
+appreciable orbital moment of about L_z=0.36 caused by multiplet interactions,
+thereby explaining the observed magnetic anisotropy. CaBaFe4O7, a member of the
+'114' oxide family, offers new opportunities to explore charge, orbital and
+spin physics in transition metal oxides.",1011.4818v1
+2013-01-29,Breathing Pyrochlore Lattice Realized in A-Site Ordered Spinel Oxides LiGaCr4O8 and LiInCr4O8,"A unique type of frustrated lattice is found in two A-site ordered spinel
+oxides, LiGaCr4O8 and LiInCr4O8. Because of the large size mismatch between Li+
+and Ga3+/In3+ ions at the A site, the pyrochlore lattice, made up of Cr3+ ions
+carrying spin 3/2, becomes an alternating array of small and large tetrahedra,
+i.e., a ""breathing"" pyrochlore lattice. We introduce a parameter, the breathing
+factor Bf, which quantifies the degree of frustration in the pyrochlore
+lattice: Bf is defined as J'/J, where J' and J are nearest-neighbor magnetic
+interactions in the large and small tetrahedra, respectively. LiGaCr4O8 with Bf
+~ 0.6 shows magnetic susceptibility similar to that of conventional Cr spinel
+oxides such as ZnCr2O4. In contrast, LiInCr4O8 with a small Bf ~ 0.1 exhibits a
+spin-gap behavior in its magnetic susceptibility, suggesting a proximity to an
+exotic singlet ground state. Magnetic long-range order occurs at 13.8 and 15.9
+K for LiGaCr4O8 and LiInCr4O8, respectively, in both cases likely owing to the
+coupling to structural distortions.",1301.6936v1
+2016-07-19,Synthesis of strontium ferrite/iron oxide exchange coupled nano-powders with improved energy product for rare earth free permanent magnet applications,"We present a simple, scalable synthesis route for producing exchange coupled
+soft/hard magnetic composite powder that outperforms pure soft and hard phase
+constituents. Importantly, the composites is iron oxide based (SrFe12O19 and
+Fe3O4) and contain no rare earth or precious metal. The two step synthesis
+process consists of first precipitating, an Iron oxide/hydroxide precursor
+directly on top of SrFe12O19 nano-flakes, ensuring a very fine degree of mixing
+between the hard and the soft magnetic phases. We then use a second step that
+serves to reduce the precursor to create the proper soft magnetic phase and
+create the intimate interface necessary for exchange coupling. We establish a
+clear processing window; at temperatures below this window the desired soft
+phase is not produced, while higher temperatures result in deleterious reaction
+at the soft/hard phase interfaces, causing an improper ratio of soft to hard
+phases. Improvements of Mr, Ms, and (BH)max are 42%, 29% and 37% respectively
+in the SrFe12O19/Fe3O4 composite compared to pure hard phase (SrFe12O19). We
+provide evidence of coupling (exchange spring behavior) with hysteresis curves,
+first order reversal curve (FORC) analysis and recoil measurements.",1607.05689v1
+2016-07-27,Magnetic Collapse and the Behavior of Transition Metal Oxides at High Pressure,"We report a detail theoretical study of the electronic structure and phase
+stability of transition metal oxides MnO, FeO, CoO, and NiO in their
+paramagnetic cubic B1 structure by employing dynamical mean-field theory of
+correlated electrons combined with \emph{ab initio} band structure methods
+(DFT+DMFT). Our calculations reveal that under pressure these materials exhibit
+a Mott insulator-metal transition (IMT) which is accompanied by a simultaneous
+collapse of local magnetic moments and lattice volume, implying a complex
+interplay between chemical bonding and electronic correlations. Moreover, our
+results for the transition pressure show a monotonous decrease from ~ 145 GPa
+to 40 GPa, upon moving from MnO to CoO. In contrast to that, in NiO, magnetic
+collapse is found to occur at remarkably higher pressure of ~ 429 GPa. We
+provide a unified picture of such a behavior and suggest that it is primary a
+localized to itinerant moment behavior transition at the IMT that gives rise to
+magnetic collapse in transition metal oxides.",1607.08261v1
+2010-05-04,Competition between Ferrimagnetism and Magnetic Frustration in Zinc Substituted YBaFe4O7,"The substitution of zinc for iron in YBaFe4O7 has allowed the oxide series
+YBaFe4-xZnxO7, with 0.40 < x < 1.50, belonging to the ""114"" structural family
+to be synthesized. These oxides crystallize in the hexagonal symmetry (P63mc),
+as opposed to the cubic symmetry (F-43m) of YBaFe4O7. Importantly, the d.c.
+magnetization shows that the zinc substitution induces ferrimagnetism, in
+contrast to the spin glass behaviour of YBaFe4O7. Moreover, a.c. susceptibility
+measurements demonstrate that concomitantly these oxides exhibit a spin glass
+or a cluster glass behaviour, which increases at the expense of ferrimagnetism,
+as the zinc content is increased. This competition between ferrimagnetism and
+magnetic frustration is interpreted in terms of lifting of the geometric
+frustration, inducing the magnetic ordering, and of cationic disordering, which
+favours the glassy state.",1005.0480v1
+2019-06-20,"Crystal structure and the magnetic properties of the 5d transition metal oxide AOsO4 (A = K, Rb, Cs)","We synthesized the 5d1-transition metal oxides AOsO4 (A = K, Rb, Cs) by
+solid-state reaction, and performed structure determination and magnetic and
+heat capacity measurements. It was found that they crystallize in a scheelite
+(A = K and Rb) or a quasi-scheelite structure (A = Cs) comprising of distorted
+diamond lattices of septivalent Os (d1) ions tetrahedrally coordinated by four
+oxide ions without local inversion symmetry; hence an antisymmetric spin-orbit
+coupling is expected in the crystals. The K and Rb compounds have Weiss
+temperatures of theta = -66 and -18 K, effective magnetic moments of mu_eff =
+1.44 and 1.45 mu_B/Os, and antiferromagnetic transition temperatures of T_N =
+36.9 and 21.0 K, respectively. In contrast, the Cs compound has theta = 12 K
+and mu_eff = 0.8 mu_B/Os without magnetic transition above 2 K, instead
+exhibiting a first-order structural transition at T_s = 152.5 K. The decline of
+the Os moment from 1.73 mu_B/Os for the simple d1 spin, particularly for Cs, is
+likely to originate from the antiparallel orbital moment, although the
+spin-orbit coupling is generally quenched in the low-lying e orbitals.",1906.08519v1
+2021-08-10,Metallic nature and site-selective magnetic collapse in iron oxide Fe4O5 at the extreme conditions of Earth's deep interior,"Properties of iron oxides at the extreme conditions are of essential
+importance in condensed matter physics and Geophysics. The recent discovery of
+a new type of iron oxide, Fe4O5, at high pressure and high temperature of
+Earth's deep interior attracts great interests. In this paper, we report the
+electronic structure and the magnetic properties of Fe4O5 predicted by the
+density functional theory plus dynamic mean field theory (DFT+DMFT) approach.
+We find that Fe4O5 stays metallic from ambient pressure to high pressure. The
+magnetic moments of iron atoms at the three different crystallographic
+positions of Fe4O5 undergo position-dependent collapse as being compressed.
+Such site-selective magnetic moment collapse originates from the shift of
+energy levels and the consequent charge transfer among the Fe-3d orbits under
+compression.",2108.04477v1
+2022-08-03,Magnetic biophysical characterization of biomimetic polyeth-ylenimine-coated nanoparticles on in vitro silico model,"Understanding the biophysical and magnetic interactions of nanoparticles
+(NPs) with cell mem-branes is critical for developing effective nanocarrier
+systems for drug delivery applications and targeted nanophysics applications.
+Recent discoveries in nanomedicine can be used to test an in vitro system that
+reproduce a similar tumor model. Iron-oxide nanoparticles can be used for
+diagnosis, as well as a good carrier of drugs and induced therapeutic for
+magnetic hyperthermia. In the present study, we engineered
+polyethylenimine-conjugated superparamagnetic iron-oxide nanoparticles (SPIONs)
+for the targeted delivery of chemotherapeutics on in vitro silico model.
+Doxorubicin is used to treat numerous types of tumors including breast cancer.
+The drug-coated mul-ti-functionalized nanoparticles, were assembled stepwise,
+with doxorubicin adsorbed to polyeth-ylenimine-iron oxide nanoparticles first,
+by electrostatic reaction and allowed for the complexation of doxorubicin.. The
+drug-coated particles were able to inhibit growth and proliferation of
+resistant cancer cells in vitro, indicating that the system has potential to
+act as an antimetastatic chemo-thermotherapeutic agent. Here, we demonstrated a
+sophisticated strategy to kill in a precise way only cancer cells by
+conjugating a magnetic nanoparticle to chemotherapeutic.",2208.02838v1
+2022-10-30,"Interplay of symmetry-conserved tunneling, interfacial oxidation and perpendicular magnetic anisotropy in CoFeB/MgO-based junctions","The interfacial oxidation level and thermodynamic properties of the MgO-based
+perpendicular magnetic tunneling junctions are investigated. The
+symmetry-conserved tunneling effect depends sensitively on the MgO adatom
+energy during the RF sputtering, as well as the thermal stability of the
+structure during the post-growth thermal annealing. Two different failure modes
+of the magnetoresistance are highlighted, involving with the decay of
+perpendicular magnetic anisotropy and destruction of coherent tunneling
+channels, respectively. Through the careful control of interfacial oxidation
+level and proper selection of the heavy metal layers, both perpendicular
+magnetic anisotropy and tunneling magnetoresistance of the junctions can be
+increased.",2210.16734v1
+2023-12-21,Magnetic Transparent Conductors for Spintronic Applications,"Transparent Conductors (TCs) exhibit optical transparency and electron
+conductivity, and are essential for many opto-electronic and photo-voltaic
+devices. The most common TCs are electron-doped oxides, which have few
+limitations when transition metals are used as dopants. Non-oxides TCs have the
+potential of extending the class of materials to the magnetic realm, bypass
+technological bottlenecks, and bring TCs to the field of spintronics. Here we
+propose new functional materials that combine transparency and conductivity
+with magnetic spin polarization that can be used for spintronic applications,
+such as spin filters. By using high-throughput first-principles techniques, we
+identified a large number of potential TCs, including non-oxides materials. Our
+results indicate that proper doping with transition metals introduces a finite
+magnetization that can provide spin filtering up to 90% in the electrical
+conductivity, still maintaining a transparency greater than 90%.",2312.13708v1
+2003-06-18,Evidence for the coexistence of low-dimensional magnetism and long-range order in Ca3CoRhO6,"We report the results of neutron powder diffraction studies on the spin-chain
+compound Ca3CoRhO6 in the temperature range 3 to 293 K. Bragg peaks due to
+magnetic ordering start appearing below about 100 K. The most interesting
+observation is that there is a diffuse magnetic peak superimposed over the
+strongest magnetic Bragg peak. The diffuse magnetic intensity is observed below
+as well above 100 K. This finding provides a new insight into the physics of
+this compound as though the low-dimensional magnetic interaction coexists with
+long range magnetic order - a novel situation among quasi one-dimensional
+oxides.",0306481v1
+2005-06-20,Monte Carlo study of half-magnetization plateau and magnetic phase diagram in pyrochlore antiferromagnetic Heisenberg model,"The antiferromagnetic Heisenberg model on a pyrochlore lattice under external
+magnetic field is studied by classical Monte Carlo simulation. The model
+includes bilinear and biquadratic interactions; the latter effectively
+describes the coupling to lattice distortions. The magnetization process shows
+a half-magnetization plateau at low temperatures, accompanied with strong
+suppression of the magnetic susceptibility. Temperature dependence of the
+plateau behavior is clarified. Finite-temperature phase diagram under the
+magnetic field is determined. The results are compared with recent experimental
+results in chromium spinel oxides.",0506500v2
+2012-09-17,Size and polydispersity effect on the magnetization of densely packed magnetic nanoparticles,"The magnetic properties of densely packed magnetic nanoparticles (MNP)
+assemblies are investigated from Monte Carlo simulations. The case of iron
+oxide nanoparticles is considered as a typical example of MNP. The main focus
+is put on particle size and size polydispersity influences on the magnetization
+curve. The particles are modeled as uniformly magnetized spheres isolated one
+from each other by a non magnetic layer representing the organic coating. A
+comparison with recent experimental results on $\gamma-$Fe$_2$O$_3$ powder
+samples differing by their size is given.",1209.3566v1
+1996-02-05,"Magnetic and Transport Properties of (La,Sr)MnO$_3$","Magnetic and transport properties of the perovskite-type $3d$
+transition-metal oxide (La,Sr)MnO$_3$ are theoretically studied using the
+double-exchange model in infinite dimension. Magnetoresistance properties as
+well as the magnetic transition temperatures are in good agreement with the
+experimental data.",9602016v1
+2004-09-03,Helicoidal ordering in iron perovskites,"We consider magnetic ordering in materials with negative charge transfer
+energy, such as iron perovskite oxides. We show that for a large weight of
+oxygen holes in conduction bands, the double exchange mechanism favors a
+helicoidal rather than ferromagnetic spin ordering both in metals, e.g. SrFeO_3
+and insulators with a small gap, e.g. CaFeO_3. We discuss the magnetic
+excitation spectrum and effects of pressure on magnetic ordering in these
+materials.",0409068v1
+2005-03-17,Signatures of Spin Glass Freezing in NiO Nanoparticles,"We present a detailed study of the magnetic properties of sol-gel prepared
+nickel oxide nanoparticles of different sizes. We report various measurements
+such as frequency, field and temperature dependence of ac susceptibility,
+temperature and field dependence of dc magnetization and time decay of
+thermoremanent magnetization. Our results and analysis show that the system
+behaves as a spin glass.",0503433v1
+2006-02-05,Magnetic properties of vanadium-oxide nanotubes probed by static magnetization and {51}V NMR,"Measurements of the static magnetic susceptibility and of the nuclear
+magnetic resonance of multiwalled vanadium-oxide nanotubes are reported. In
+this nanoscale magnet the structural low-dimensionality and mixed valency of
+vanadium ions yield a complex temperature dependence of the static
+magnetization and the nuclear relaxation rates. Analysis of the different
+contributions to the magnetism allows to identify individual interlayer
+magnetic sites as well as strongly antiferromagnetically coupled vanadium spins
+(S = 1/2) in the double layers of the nanotube's wall. In particular, the data
+give strong indications that in the structurally well-defined vanadium-spin
+chains in the walls, owing to an inhomogeneous charge distribution,
+antiferromagnetic dimers and trimers occur. Altogether, about 30% of the
+vanadium ions are coupled in dimers, exhibiting a spin gap of the order of 700
+K, the other ~ 30% comprise individual spins and trimers, whereas the remaining
+\~ 40% are nonmagnetic.",0602114v2
+2013-05-09,Origin of interface magnetism in BiMnO3/SrTiO3 and LaAlO3/SrTiO3 heterostructures,"Possible ferromagnetism induced in otherwise non-magnetic materials has been
+motivating intense research in complex oxide heterostructures. Here we show
+that a confined magnetism is realized at the interface between SrTiO3 and two
+insulating polar oxides, BiMnO3 and LaAlO3. By using polarization dependent
+x-ray absorption spectroscopy, we find that in both cases the magnetic order is
+stabilized by a negative exchange interaction between the electrons transferred
+to the interface and local magnetic moments. These local magnetic moments are
+associated to Ti3+ ions at the interface itself for LaAlO3/SrTiO3 and to Mn3+
+ions in the overlayer for BiMnO3/SrTiO3. In LaAlO3/SrTiO3 the induced magnetic
+moments are quenched by annealing in oxygen, suggesting a decisive role of
+oxygen vacancies in the stabilization of interfacial magnetism.",1305.2226v2
+2020-07-16,Crystal and Magnetic Structure of Polar Oxide HoCrWO$_6$,"Polar magnetic oxide HoCrWO$_6$ is synthesized and its crystal structure,
+magnetic structure, and thermodynamic properties are investigated. HoCrWO$_6$
+forms the polar crystal structure (space group Pna2$_1$ (#33)) due to the
+cation ordering of W$^{6+}$ and Cr$^{3+}$. There is an antiferromagnetic
+transition at TN = 24.5 K along with the magnetic entropy change (~5
+J.Kg.$^{-1}$K$^{-1}$ at 70 kOe). Neutron diffraction measurement indicates that
+both Cr and Ho sublattices are ordered with the moment of 2.32(5)$\mu_B$ and
+8.7(4)$\mu_B$ at 2 K, respectively. While Cr forms A-type collinear
+antiferromagnetic (AFM) structure with magnetic moment along the $b$ axis, Ho
+sublattice orders in a non-coplanar AFM arrangement. A comparison with
+isostructural DyFeWO$_6$ and DyCrWO$_6$ indicates that the magnetic structure
+of this family of compounds is controlled by the presence or absence of eg
+electrons in the transition metal sublattice.",2007.08581v1
+2012-05-09,Magnetically ordered state at correlated oxide interfaces: the role of random oxygen defects,"Using an effective one-band Hubbard model with disorder, we consider magnetic
+states of the correlated oxide interfaces, where effective hole self-doping and
+a magnetially ordered state emerge due to electronic and ionic reconstructions.
+By employing the coherent potential approximation, we analyze the effect of
+random oxygen vacancies on the two-dimensional magnetism. We find that the
+random vacancies enhance the ferromagnetically ordered state and stabilize a
+robust magnetization above a critical vacancy concentration of about c=0.1. In
+the strong-correlated regime, we also obtain a nonmonotonic increase of the
+magnetization upon an increase of vacancy concentration and a substantial
+increase of the magnetic moments, which can be realized at oxygen reduced
+high-Tc cuprate interfaces.",1205.1981v1
+2023-02-03,Defect-induced magnetism in TiO$_2$: An example of quasi 2D magnetic order with perpendicular anisotropy,"Magnetic order at room temperature induced by atomic lattice defects, like
+vacancies, interstitials or pairs of them, has been observed in a large number
+of different nonmagnetic hosts, such as pure graphite, oxides and silicon-based
+materials. High Curie temperatures and time independent magnetic response at
+room temperature indicate the extraordinary robustness of this new phenomenon
+in solid state magnetism. In this work, we review experimental and theoretical
+results in pure TiO$_2$ (anatase), which magnetic order can be triggered by
+low-energy ion irradiation. In particular, we discuss the systematic
+observation of an ultrathin magnetic layer with perpendicular magnetic
+anisotropy at the surface of this oxide.",2302.01803v1
+2012-08-02,Strong electronic correlation and strain effects at the interfaces between polar and nonpolar complex oxides,"The interface between the polar LaAlO$_3$ and nonpolar SrTiO$_3$ layers has
+been shown to exhibit various electronic and magnetic phases such as two
+dimensional electron gas, superconductivity, magnetism and electronic phase
+separation. These rich phases are expected due to the strong interplay between
+charge, spin and orbital degree of freedom at the interface between these
+complex oxides, leading to the electronic reconstruction in this system.
+However, until now all of these new properties have been studied extensively
+based on the interfaces which involve a polar LaAlO$_3$ layer. To investigate
+the role of the A and B cationic sites of the ABO$_3$ polar layer, here we
+study various combinations of polar/nonpolar oxide (NdAlO$_3$/SrTiO$_3$,
+PrAlO$_3$/SrTiO$_3$ and NdGaO$_3$/SrTiO$_3$) interfaces which are similar in
+nature to LaAlO$_3$/SrTiO$_3$ interface. Our results show that all of these new
+interfaces can also produce 2DEG at their interfaces, supporting the idea that
+the electronic reconstruction is the driving mechanism for the creation of the
+2DEG at these oxide interfaces. Furthermore, the electrical properties of these
+interfaces are shown to be strongly governed by the interface strain and strong
+correlation effects provided by the polar layers. Our observations may provide
+a novel approach to further tune the properties of the 2DEG at the selected
+polar/nonpolar oxide interfaces.",1208.0410v1
+2020-09-17,Anodic Oxidation of Epitaxial Superconductor-Semiconductor Hybrids,"We demonstrate a new fabrication process for hybrid
+semiconductor-superconductor heterostructures based on anodic oxidation (AO),
+allowing controlled thinning of epitaxial Al films. Structural and transport
+studies of oxidized epitaxial Al films grown on insulating GaAs substrates
+reveal spatial non-uniformity and enhanced critical temperature and magnetic
+fields. Oxidation of epitaxial Al on hybrid InAs heterostructures with a
+conducting quantum well show similarly enhanced superconducting properties
+transferred to the two-dimensional electron gas (2DEG) by proximity effect,
+with critical perpendicular magnetic fields up to 3.5 T. An insulating AlOx
+film, that passivates the heterostructure from exposure to air, is obtained by
+complete oxidation of the Al. It simultaneously removes the need to strip Al
+which damages the underlying semiconductor. AO passivation yielded 2DEG
+mobilities two times higher than similar devices with Al removed by wet
+etching. An AO-passivated Hall bar showed quantum Hall features emerging at a
+transverse field of 2.5 T, below the critical transverse field of thinned
+films, eventually allowing transparent coupling of quantum Hall effect and
+superconductivity. AO thinning and passivation are compatible with standard
+lithographic techniques, giving lateral resolution below <50 nm. We demonstrate
+local patterning of AO by realizing a semiconductor-based Josephson junction
+operating up to 0.3 T perpendicular.",2009.08190v1
+2021-05-02,Tunable Néel-Bloch magnetic twists in Fe3GeTe2 with van der Waals structure,"The advent of ferromagnetism in two-dimensional (2D) van der Waals (vdW)
+magnets has stimulated high interest in exploring topological magnetic
+textures, such as skyrmions for use in future skyrmion-based spintronic
+devices. To engineer skyrmions in vdW magnets by transforming Bloch-type
+magnetic bubbles into N\'eel-type skyrmions, the heterostructure of heavy
+metal/vdW magnetic thin film has been made to induce interfacial
+Dzyaloshinskii-Moriya interaction (DMI). However, the unambiguous
+identification of the magnetic textures inherent to vdW magnets, e.g., whether
+the magnetic twists (skyrmions/domain walls) are N\'eel- or Bloch-type, is
+unclear. Here we demonstrate that the N\'eel- or Bloch-type magnetic twists can
+be tuned in the vdW magnet Fe3GeTe2 (FGT) with/without interfacial DMI. We use
+an in-plane magnetic field to align the modulation wavevector q of the
+magnetizations in order to distinguish the N\'eel- or Bloch-type magnetic
+twists. We observe that q is perpendicular to the in-plane field in the
+heterostructure (Pt/oxidized-FGT/FGT/oxidized-FGT), while q aligns at a rotated
+angle with respect to the field direction in the thin plate by thinning bulk
+FGT. We find that the aligned domain wall twists hold fan-like modulations,
+coinciding qualitatively with our computational results.",2105.00468v1
+1998-09-05,Coexistence of the Electron Cooper Pair and Antiferromagnetic Short-Range Correlation in Copper Oxide Materials,"Within the fermion-spin theory, the physical properties of the electron
+pairing state in the copper oxide materials are discussed. According to the
+common form of the electron Cooper pair, it is shown that there is a
+coexistence of the electron Cooper pair and magnetic short-range correlation,
+and hence the antiferromagnetic short-range correlation can persist into the
+superconducting state. Moreover, the mean-field results indicate that the
+electron pairing state originating from the pure magnetic interaction in the
+two-dimensional t-J model is the local state, and then does not reveal the true
+superconducting ground-state.",9809098v2
+2003-03-06,Orbital Ordering and Orbital Fluctuations in Transition Metal Oxides,"We summarize some characteristic features of the frustrated magnetic
+interactions in spin-orbital models adequate for cubic transition metal oxides
+with orbital degeneracy. A generic tendency towards dimerization, found already
+in the degenerate Hubbard model, is confirmed for $t_{2g}$ but not for $e_g$
+systems. In the $t_{2g}$ case the quantum orbital fluctuations are more
+pronounced and contribute to a stronger competition between different magnetic
+and orbital states. Therefore the orbital liquid states exist in some undoped
+$t_{2g}$ systems, while in the manganites such states can be triggered only by
+doping.",0303113v1
+2004-07-27,Composition dependent magnetic properties of iron oxide - polyaniline nanoclusters,"Gamma - Iron Oxide prepared by sol -gel process was used to produce
+nanocomposites with polyaniline of varying aniline concentrations. TEM shows
+the presence of chain like structure for lower polyaniline concentration. The
+room temperature hysteresis curves show finite coercivity of 160 Oe for all the
+composites while the saturation magnetization was found to decrease with
+increasing polymer content. ZFC - FC magnetisation measurements indicate high
+blocking temperatures. It is believed that this indicates a strongly
+interacting system, which is also shown by our TEM results. Monte Carlo
+simulations performed on a random anisotropy model with dipolar and exchange
+inteactions match well with experimental results.",0407693v1
+2006-11-29,Room temperature tunneling anisotropic and collinear magnetoresistance,"We report a room temperature tunneling anisotropic magnetoresistance in
+Co/Al2O3/NiFe junctions containing magnetic electrodes oxidized prior to
+forming the Al2O3 layer. A significant change in a tunnel magnetoresistance is
+observed when the layer magnetizations are rotated collinearly in the junction
+plane by an applied external field. The angular dependence of the tunneling
+anisotropic magnetoresistance could be explained by the presence of an
+antiferromagnetic oxide layer formed within the barrier.",0611751v1
+2010-06-30,Control of the structural and magnetic properties of perovskite oxide ultrathin films through the substrate symmetry effect,"Perovskite transition-metal oxides are networks of corner-sharing octahedra
+whose tilts and distortions are known to affect their electronic and magnetic
+properties. We report calculations on a model interfacial structure to avoid
+chemical influences and show that the symmetry mismatch imposes an interfacial
+layer with distortion modes that do not exist in either bulk material, creating
+new interface properties driven by symmetry alone. Depending on the resistance
+of the octahedra to deformation, the interface layer can be as small as one
+unit cell or extend deep into the thin film.",1006.5758v1
+2011-06-28,Oxygen adsorption effect on magnetic properties of graphite,"Both experimental and theoretical studies of the magnetic properties of
+micrographite and nanographite indicate a crucial role of the partial oxidation
+of graphitic zigzag edges in ferromagnetism. In contrast to total and partial
+hydrogenation, the oxidation of half of the carbon atoms on the graphite edges
+transforms the antiferromagnetic exchange interaction between graphite planes
+and over graphite ribbons to the ferromagnetic interaction. The stability of
+the ferromagnetism is discussed.",1106.5565v1
+2013-08-19,Spirals and skyrmions in two dimensional oxide heterostructures,"We construct the general free energy governing long-wavelength magnetism in
+two-dimensional oxide heterostructures, which applies irrespective of the
+microscopic mechanism for magnetism. This leads, in the relevant regime of weak
+but non-negligible spin-orbit coupling, to a rich phase diagram containing
+in-plane ferromagnetic, spiral, cone, and skyrmion lattice phases, as well as a
+nematic state stabilized by thermal fluctuations. The general conclusions are
+vetted by a microscopic derivation for a simple model with Rashba spin-orbit
+coupling.",1308.4179v2
+2017-06-16,Electronic and magnetic properties of epitaxial SrRhO3 films,"Strong interplay of fundamental order parameters in complex oxides are known
+to give rise to exotic physical phenomena. The 4d transition metal oxide SrRhO3
+has generated much interest, but advances have been hindered by difficulties in
+preparing single crystalline phases. Here, we have epitaxially stabilized high
+quality single crystalline SrRhO3 films and investigated their structural,
+electronic, and magnetic properties. We determine that their properties
+significantly differ from the paramagnetic metallic ground state that governs
+bulk samples and are strongly related to rotations of the RhO6 octahedra.",1706.05409v1
+2017-07-26,Magnetism from intermetallics and perovskite oxides,"This work has been presented by RJCV to obtain his PhD degree at Fluminense
+Federal University, in March of 2017. We focused on the synthesis of compounds
+and then on their magneto-strucutral characterization; mainly due to the
+interplay of these physical properties. We have prepared intermetallic alloys
+(including Heusler alloys) and perovskite oxides (manganites and cobaltites);
+in bulk and nanoparticles. A thorough analysis of the influence of the
+morphology and crystal structure on the magnetic properties of these compounds
+is addressed.",1707.09868v2
+2019-10-09,Electric-field control of magnetism in iron oxide nanoparticle / BaTiO3 film composites,"We study composites of monodisperse ferrimagnetic nanoparticles (NPs)
+embedded into ferroelectric barium titanate (BTO) films. The BTO films were
+prepared by pulsed laser deposition. The composite consists of a stack of two
+BTO films sandwiching one monolayer of iron oxide NPs. We observe a
+magnetoelectric coupling due to strain and interface charge co-mediation
+between the BTO and the NPs. This is demonstrated by measurements of the
+magnetization as function of DC and AC electric fields.",1910.04127v1
+2019-02-17,Redox-controlled epitaxy and magnetism of oxide heterointerfaces: EuO/SrTiO$_3$,"We demonstrate a novel route to prepare thin films of the ferromagnetic
+insulator Europium monoxide. Key is a redox-controlled interface reaction
+between metallic Eu and the substrate SrTiO$_3$ as the supplier of oxygen. The
+process allows tuning the electronic, magnetic and structural properties of the
+EuO films. Furthermore, we apply this technique to various oxidic substrates
+and demonstrate the universality and limits of a redox-controlled EuO film
+synthesis.",1902.06301v1
+2019-12-23,Electronic and magnetic properties of structural defects in SrTiO$_3$(Co),"The synthesis conditions of SrTiO$_3$(Co) samples in which cobalt
+predominantly enters the $A$ or $B$ sites of the perovskite $AB$O$_3$ structure
+are found. EXAFS studies show that the Co impurity at the $A$ site is
+off-center and is displaced from the site by 1.0 {\AA}. XANES studies reveal
+two predominant oxidation states of Co: Co$^{2+}$ at the $A$ site and Co$^{3+}$
+at the $B$ site. First-principles calculations of a number of possible
+cobalt-containing structural defects reveal defects whose properties are
+compatible with the experimentally observed Co oxidation state, its local
+structure, magnetic, electrical, and optical properties.",1912.10711v1
+2020-03-12,Superconductor-Insulator Transition and the Crossover to Non Equilibrium in two-dimensional Indium - Indium-Oxide composite,"Magnetic-field tuned superconductor to insulator transition was observed in a
+novel hybrid system of granular superconducting indium, deposited on indium
+oxide thin film, which exhibits global superconductivity at low magnetic
+fields. We have used annealing to tune the coupling to lie just at the
+borderline where superconductivity in the underlying InOx is suppressed, which
+is also close to the metal-insulator transition of the InOx. The hybrid system
+exhibits a ""giant"" magnetoresistance above the H-SIT, with critical behavior
+that manifests the duality between Cooper pairs and vortices.",2003.05723v2
+2024-02-28,Harnessing the Duality of Magnetism and Conductivity: A Review of Oxide based Dilute Magnetic Semiconductors,"Over the last two decades, the new branch of spintronics, i.e., semiconductor
+spintronics, has gained more attention because it integrates the
+characteristics of conventional semiconductors, such as optical bandgap and
+charge carriers, helpful for processing and computing pieces of information
+combined with magnets for data storage applications in a single device.
+Likewise, substituting transition metal (TM) ions to induce magnetic qualities
+into semiconductors or oxides creates dilute magnetic semiconductors (DMSs) or
+oxides (DMOs) with high electronic, photonic, and magnetic functionality. This
+review article discusses the historical outline of magnetic semiconductors with
+their origin and mechanism. It also includes a concise overview of various DMO
+systems based on their conductivity (p-type and n-type) to elucidate the
+synthesis, origin, and control mechanisms and further evoke the prepared
+spintronics devices. The occurrence of RTFM with transparency and conductivity
+can be helpful in spintronics device fabrications, which was assumed to be
+governed by the formation of intrinsic defects, charge carriers, morphology,
+and the induced exchange interactions between ions. The DMOs-based spintronics
+devices, such as magneto-optical devices, transparent ferromagnets, and
+spin-based solar cells, exploit both semiconducting and magnetic properties,
+which have also been discussed in this review article with outlook and
+perspectives.",2402.18173v1
+2021-12-13,Mechanism of Spin-Orbit Torques in Platinum Oxide Systems,"Spin-Orbit Torque (SOT) Magnetic Random-Access Memories (MRAM) have shown
+promising results towards the realization of fast, non-volatile memory systems.
+Oxidation of the heavy-metal (HM) layer of the SOT-MRAM has been proposed as a
+method to increase its energy efficiency. But the results are widely divergent
+due to the difficulty in controlling the HM oxidation because of its low
+enthalpy of formation. Here, we reconcile these differences by performing a
+gradual oxidation procedure, which allows correlating the chemical structure to
+the physical properties of the stack. As an HM layer, we chose Pt because of
+the strong SOT and the low enthalpy of formation of its oxides. We find
+evidence of an oxide inversion layer at the FM/HM interface: the oxygen is
+drawn into the FM, while the HM remains metallic near the interface. We further
+demonstrate that the oxygen migrates in the volume of the FM layer rather than
+being concentrated at the interface. Consequently, we find that the intrinsic
+magnitude of the SOT is unchanged compared to the fully metallic structure. The
+previously reported apparent increase of SOTs is not intrinsic to platinum
+oxide and instead arises from systemic changes produced by oxidation.",2112.07034v1
+2023-07-05,Heterophased grain boundary-rich superparamagnetic Iron Oxides/carbon composite for Cationic and Anionic Dye Removal,"Iron oxide-based nanostructures receive significant attention as an efficient
+adsorbent for organic dyes removal. The removal properties have strong
+dependency on the stoichiometry, phases, reactive edges, defect states etc
+present in the iron-oxides nanostructures. Herein, iron oxide/carbon composite
+with well-defined heterophased grain boundaries is synthesized by simple
+precipitation method and followed by calcination. The local structure, spin
+dynamics and magnetic properties of heterophased iron oxides/carbon composite
+are thoroughly investigated to explore its cationic and anionic dye removal
+capability. To validate the effectivity of the presence of heterogeneous grain
+boundaries, iron oxide/carbon nanocomposite with homogeneous grain boundaries
+is also examined. It was found that the hetero-phased iron oxide/carbon showed
+removal capacity of 35.45 mg g-1 and 45.84 mg g-1 for cationic (Crystal Violet)
+and anionic (Congo Red) dyes, respectively as compared to that of
+as-synthesised imidazole-capped superparamagnetic {\alpha}-Fe2O3 (25.11 mg g-1
+and 40.44 mg g-1, respectively) and homophased iron oxide/carbon nanocomposite
+(9.41 mg g-1 and 5.43 mg g-1, respectively). The plausible mechanism on the
+local structural evolution of the heterophase in the course of calcination and
+increase of the removal capacity is discussed. A detailed dye adsorption
+investigation is presented including the adsorption kinetic study. The
+pseudo-second order kinetic model is found to be an appropriate one and
+suggests that the chemisorption is dominant factor leading to adsorption of
+dyes. Whereas Weber-Morris model indicate the strong influence of boundary
+layers of nanocomposite on the adsorption process.",2307.02142v1
+2008-04-04,Magnetic Order versus superconductivity in the Iron-based layered La(O1-xFx)FeAs systems,"In high-transition temperature (high-Tc) copper oxides, it is generally
+believed that antiferromagnetism plays a fundamental role in the
+superconducting mechanism because superconductivity occurs when mobile
+electrons or holes are doped into the antiferromagnetic parent compounds. The
+recent discovery of superconductivity in the rare-earth (R) iron-based oxide
+systems [RO1-xFxFeAs] has generated enormous interest because these materials
+are the first noncopper oxide superconductors with Tc exceeding 50 K. The
+parent (nonsuperconducting) LaOFeAs material is metallic but shows anomalies
+near 150 K in both resistivity and dc magnetic susceptibility. While optical
+conductivity and theoretical calculations suggest that LaOFeAs exhibits a
+spin-density-wave (SDW) instability that is suppressed with doping electrons to
+form superconductivity, there has been no direct evidence of the SDW order.
+Here we use neutron scattering to demonstrate that LaOFeAs undergoes an abrupt
+structural distortion below ~150 K, changing the symmetry from tetragonal
+(space group P4/nmm) to monoclinic (space group P112/n) at low temperatures,
+and then followed with the development of long range SDW-type antiferromagnetic
+order at ~134 K with a small moment but simple magnetic structure. Doping the
+system with flourine suppresses both the magnetic order and structural
+distortion in favor of superconductivity. Therefore, much like high-Tc copper
+oxides, the superconducting regime in these Fe-based materials occurs in close
+proximity to a long-range ordered antiferromagnetic ground state. Since the
+discovery of long",0804.0795v1
+2017-10-31,Electric-field control of oxygen vacancy and magnetic phase transition in cobaltite/manganite bilayer,"Manipulation of oxygen vacancies (V_O) in single oxide layers by varying the
+electric field can result in significant modulation of the ground state.
+However, in many oxide multilayers with strong application potentials, e.g.
+ferroelectric tunnel junctions and solid-oxide fuel cells, understanding V_O
+behaviour in various layers under an applied electric field remains a
+challenge, owing to complex V_O transport between different layers. By sweeping
+the external voltage, a reversible manipulation of V_O and a corresponding
+fixed magnetic phase transition sequence in cobaltite/manganite
+(SrCoO3-x/La0.45Sr0.55MnO3-y) heterostructures are reported. The magnetic phase
+transition sequence confirms that the priority of electric-field-induced V_O
+formation/annihilation in the complex bilayer system is mainly determined by
+the V_O formation energies and Gibbs free energy differences, which is
+supported by theoretical analysis. We not only realize a reversible
+manipulation of the magnetic phase transition in an oxide bilayer, but also
+provide insight into the electric field control of V_O engineering in
+heterostructures.",1712.01355v1
+2021-10-06,"Stacking-order effect on spin-orbit torque, spin-Hall magnetoresistance, and magnetic anisotropy in Ni$_{81}$Fe$_{19}$-IrO$_2$ bilayers","The 5d transition-metal oxides have been an intriguing platform to
+demonstrate efficient charge to spin current conversion due to a unique
+electronic structure dominated by strong spin-orbit coupling. Here, we report
+on stacking-order effect of spin-orbit torque (SOT), spin-Hall
+magnetoresistance, and magnetic anisotropy in bilayer Ni$_{81}$Fe$_{19}$-5d
+iridium oxide, IrO$_2$. While all the IrO$_2$ and Pt control samples exhibit
+large dampinglike-SOT generation stemming from the efficient charge to spin
+current conversion, the magnitude of the SOT is larger in the IrO$_2$
+(Pt)-bottom sample than in the IrO$_2$ (Pt)-top one. The fieldlike-SOT has even
+more significant stack order effect, resulting in an opposite sign in the
+IrO$_2$ samples in contrast to the same sign in the Pt samples. Furthermore, we
+observe that the magnetic anisotropy energy density and the anomalous Hall
+effect are increased in the IrO$_2$ (Pt)-bottom sample, suggesting enhanced
+interfacial perpendicular magnetic anisotropy. Our findings highlight the
+significant influence of the stack order on spin transport and magnetotransport
+properties of Ir oxide/ferromagnet systems, providing useful information on
+design of SOT devices including 5d transition-metal oxides.",2110.02517v1
+2001-06-19,The oxidation state at tunnel junction interfaces,"We demonstrate that at the usual 1E-7 torr range of base pressures in the
+sputtering chamber, X-ray photoelectron spectroscopy shows the existence of a
+thin AlOx layer at the Nb/Al interface in both Nb/Al-AlOx/Pb tunnel junctions
+and Nb/Al bilayers. This is due to the time elapsed between the deposition of
+the Nb and Al bottom layers, even at times as short as 100 s. We also give some
+direct evidence of the oxidation of the top Pb electrode on the Nb electrode
+surface. Such oxidation probably occurs at the pinholes of the intermediate
+Al-AlOx layer of the junctions, as a consequence of the oxidation state at the
+Nb/Al interface. We therefore suggest that both the base pressure and the time
+lapse between layer depositions should be carefully controlled in magnetic
+tunnel junctions.",0106376v1
+2005-01-31,Specific Heat of the beta-Pyrochlore Oxide Superconductors CsOs2O6 and RbOs2O6,"Two beta-pyrochlore oxide superconductors, CsOs2O6 and RbOs2O6, are studied
+thermodynamically by measuring specific heat on polycrystalline samples. It is
+found that a Sommerfeld coefficient ? is nearly equal, 20 mJ/K2 mol Os, in the
+two oxides with different superconducting transition temperatures; Tc = 3.3 K
+and 6.3 K, respectively. This suggests that the density of states at the Fermi
+level is not a crucial parameter to determine the Tc of the beta-pyrochlore
+oxide superconductors, which is incompatible with the general expectation for a
+conventional BCS-type superconductor. Anomalous lattice contributions to
+specific heat at low temperature are also reported, which may come from nearly
+localized phonon modes associated with the rattling of the alkali metal ions
+weakly bound in an oversized cage formed by OsO6 octahedra.",0501736v3
+2005-04-13,Growth Mechanisms and Oxidation-Resistance of Gold-Coated Iron Nanoparticles,"We report the chemical synthesis of Fe-core/Au-shell nanoparticles by a
+reverse micelle method, and the investigation of their growth mechanisms and
+oxidation-resistant characteristics. The core-shell structure and the presence
+of the Fe & Au phases have been confirmed by transmission electron microscopy,
+energy dispersive spectroscopy, X-ray diffraction, Mossbauer spectroscopy, and
+inductively coupled plasma techniques. Additionally, atomic-resolution
+Z-contrast imaging and electron energy loss spectroscopy (EELS) in a scanning
+transmission electron microscope (STEM) have been used to study details of the
+growth processes. The Au-shell grows by nucleating on the Fe-core surface
+before coalescing. The magnetic moments of such nanoparticles, in the loose
+powder form, decrease over time due to oxidation. The less than ideal
+oxidation-resistance of the Au shell may have been caused by the rough Au
+surfaces. However, in the pressed pellet form, electrical transport
+measurements show that the particles are fairly stable, as the resistance of
+the pellet does not change appreciably over time.",0504314v1
+2014-01-08,Nanoscale Phenomena in Oxide Heterostructures,"Recent advances in creating complex oxide heterostructures, interfaces formed
+between two different transition metal oxides, have heralded a new era of
+materials and physics research, enabling a uniquely diverse set of coexisting
+physical properties to be combined with an ever- increasing degree of
+experimental control. Already, these systems have exhibited such varied
+phenomena as superconductivity, magnetism, and ferroelasticity, all of which
+are gate-tunable, demonstrating their promise for fundamental discovery and
+technological innovation alike. To fully exploit this richness, it is necessary
+to understand and control the physics on the smallest scales, making the use of
+nanoscale probes essential. Using the prototypical LaAlO$_3$/SrTiO$_3$
+interface as a guide, we explore the exciting developments in the physics of
+oxide-based heterostructures, with a focus on nanostructures and the nanoscale
+probes employed to unravel their complex behavior.",1401.1772v1
+2020-07-03,Ferroelectric Exchange Bias Affects Interfacial Electronic States,"In polar oxide interfaces phenomena such as conductivity, superconductivity,
+magnetism, one-dimensional conductivity and Quantum Hall states can emerge at
+the polar discontinuity. Combining controllable ferroelectricity at such
+interfaces can affect the superconducting properties and shed light on the
+mutual effects between the polar oxide and the ferroelectric oxide. Here we
+study the interface between the polar oxide LaAlO3 and the ferroelectric
+Ca-doped SrTiO3 by means of electrical transport combined with local imaging of
+the current flow with the use of scanning Superconducting Quantum Interference
+Device (SQUID). Anomalous behavior of the interface resistivity is observed at
+low temperatures. The scanning SQUID maps of the current flow suggest that this
+behavior originates from an intrinsic bias induced by the polar LaAlO3 layer.
+Our data imply that the intrinsic bias combined with ferroelectricity constrain
+the possible structural domain tiling near the interface. We recommend the use
+of this intrinsic bias as a method of controlling and tuning the initial state
+of ferroelectric materials by design of the polar structure. The hysteretic
+dependence of the normal and the superconducting state properties on gate
+voltage can be utilized in multifaceted controllable memory devices.",2007.01785v1
+2016-11-26,Band alignment and charge transfer in complex oxide interfaces,"The synthesis of transition metal heterostructures is currently one of the
+most vivid fields in the design of novel functional materials. In this paper we
+propose a simple scheme to predict \emph{band alignment }and \emph{charge
+transfer} in complex oxide interfaces. For semiconductor heterostructures band
+alignment rules like the well known Anderson or Schottky-Mott rule are based on
+comparison of the work function or electron affinity of the bulk components.
+This scheme breaks down for oxides due to the invalidity of a single
+workfunction approximation as recently shown (Phys. Rev. B 93, 235116; Adv.
+Funct. Mater. 26, 5471). Here we propose a new scheme which is built on a
+continuity condition of valence states originating in the compounds' shared
+network of oxygen. It allows for the prediction of sign and relative amplitude
+of the intrinsic charge transfer, taking as input only information about the
+bulk properties of the components. We support our claims by numerical density
+functional theory simulations as well as (where available) experimental
+evidence. Specific applications include i) controlled doping of SrTiO$_3$
+layers with the use of 4$d$ and 5$d$ transition metal oxides and ii) the
+control of magnetic ordering in manganites through tuned charge transfer.",1611.08689v1
+2016-05-23,Direct evidence for charge stripes in a layered cobalt oxide,"Recent experiments indicate that static stripe-like charge order is generic
+to the hole-doped copper oxide superconductors and competes with
+superconductivity. Here we show that a similar type of charge order is present
+in La$_{5/3}$Sr$_{1/3}$CoO$_4$, an insulating analogue of the copper oxide
+superconductors containing cobalt in place of copper. The stripe phase we have
+detected is accompanied by short-range, quasi-one-dimensional,
+antiferromagnetic order, and provides a natural explanation for the distinctive
+hourglass shape of the magnetic spectrum previously observed in neutron
+scattering measurements of La$_{5/3}$Sr$_{1/3}$CoO$_4$ and many hole-doped
+copper oxide superconductors. The results establish a solid empirical basis for
+theories of the hourglass spectrum built on short-range, quasi-static, stripe
+correlations.",1605.07087v1
+2017-06-07,"Effect of oxygen vacancy on structural, electronic and magnetic properties of La-based oxide interfaces","Disorder, primarily in the form of oxygen vacancies, cation stoichiometry and
+atomic inter-diffusion, appear to play vital roles in the electronic and
+transport properties of the metallic electron liquid at the oxide
+hetero-interfaces. Antisite disorder is also understood to be a key player in
+this context. In order to delineate the roles of two of these key factors,
+oxygen vacancy and antisite disorder, we have investigated the effect of oxygen
+vacancy on the antisite disorder at a number of interfaces separating two
+La-based transition metal oxides using density functional theory. Oxygen
+vacancy is found to suppress the antisite disorder in some heterostructures and
+thereby stabilizes the ordered structure, while in some other systems it tends
+to drive the disorder. Thus by controlling the oxygen partial pressure during
+the growth, it is possible to engineer the antisite disorder in many oxide
+heretostructures.",1706.02210v2
+2017-05-08,Origin of the crossover from polarons to Fermi liquids in transition metal oxides,"Transition metal oxides (TMOs) host a wealth of exotic phenomena ranging from
+charge, orbital, and magnetic order to nontrivial topological phases and
+superconductivity. In order to translate these unique materials properties into
+novel device functionalities, TMOs must be doped. However, the nature of
+carriers in doped oxides and their conduction mechanism at the atomic scale
+remain unclear. Recent angle-resolved photoelectron spectroscopy (ARPES)
+investigations provided new insight into these questions, revealing that the
+carriers of prototypical metal oxides undergo a transition from a polaronic
+liquid to a Fermi liquid regime with increasing doping. Here, by performing
+\textit{ab initio} many-body calculations of the ARPES spectra of TiO$_2$, we
+show that this transition originates from non-adiabatic polar electron-phonon
+coupling, and occurs when the frequency of plasma oscillations exceeds that of
+longitudinal-optical phonons. This finding suggests that a universal mechanism
+may underlie polaron formation in TMOs, and provides a new paradigm for
+engineering emergent properties in quantum matter.",1705.02967v1
+2018-03-08,Topological Properties and Functionalities in Oxide Thin Films and Interfaces,"As symbolized by the Nobel Prize in Physics 2016, ""topology"" has been
+recognized as an essential standpoint to understand and control the physics of
+condensed matter. This concept may be spreading even into application areas
+such as novel electronics. In this trend, there has been reported a number of
+study for the oxide films and heterostructures with topologically non-trivial
+electronic or magnetic states. In this review, we overview the trends of new
+topological properties and functionalities in oxide materials with sorting out
+a number of examples. The technological advances in oxide film growth achieved
+over the last few decades are now opening the door for harnessing novel
+topological properties.",1803.03050v1
+2018-08-17,Universal superconducting precursor in perovskite-based oxides,"A pivotal challenge posed by unconventional superconductors is to unravel how
+superconductivity emerges upon cooling from the generally complex normal state.
+Some of the most prominent unconventional superconductors are oxides: strontium
+titanate, strontium ruthenate, and the cuprates exhibit greatly different
+superconducting transition temperatures $T_c$, and although their respective
+superconducting pairing mechanisms remain unknown, they are thought to differ
+as well. Here we use nonlinear magnetic response, a probe that is uniquely
+sensitive to the superconducting precursor, to uncover remarkable universal
+behavior in these three distinct classes of superconductors. We find unusual
+exponential temperature dependence of the diamagnetic response above the
+transition temperature $T_c$, with a characteristic temperature scale that
+strongly varies with $T_c$. We correlate this scale with the sensitivity of
+$T_c$ to local stress, and show that it is influenced by intentionally-induced
+structural disorder. The universal behavior is therefore caused by intrinsic,
+self-organized structural inhomogeneity, inherent to the oxides
+perovskite-based structure. The prevalence of such inhomogeneity has
+far-reaching implications for the interpretation of electronic properties of
+perovskite-related oxides in general.",1808.05763v2
+2020-09-21,Characterizing oxygen atoms in perovskite and pyrochlore oxides using ADF-STEM at a resolution of a few tens of picometers,"We present an aberration corrected scanning transmission electron microscopy
+(ac-STEM) analysis of the perovskite (LaFeO3) and pyrochlore (Yb2Ti2O7 and
+Pr2Zr2O7) oxides and demonstrate that both the shape and contrast of visible
+atomic columns in annular dark-field (ADF) images are sensitive to the presence
+of nearby atoms of low atomic number (e.g. oxygen). We show that point defects
+(e.g. oxygen vacancies), which are invisible - or difficult to observe due to
+limited sensitivity - in X-ray and neutron diffraction measurements, are the
+origin of the complex magnetic ground state of pyrochlore oxides. In addition,
+we present, for the first time, a method by which light atoms can be resolved
+in quantitative ADF-STEM images. Using this method, we resolved oxygen atoms in
+perovskite and pyrochlore oxides.",2009.10037v1
+2022-04-25,Ab-initio study of magneto-ionic mechanisms in ferromagnet/oxide multilayers,"The application of gate voltages in heavy metal/ferromagnet/Oxide multilayer
+stacks has been identified as one possible candidate to manipulate their
+anisotropy at will. However, this method has proven to show a wide variety of
+behaviours in terms of reversibility, depending on the nature of the
+metal/oxide interface and its degree of oxidation. In order to shed light on
+the microscopic mechanism governing the complex magneto-ionic behaviour in
+$\text{Ta/CoFeB/}\text{HfO}_2$, we perform ab-initio simulations on various
+setups comprising $\text{Fe/O, Fe/HfO}_2$ interfaces with different oxygen atom
+interfacial geometries. After the determination of the more stable interfacial
+configurations, we calculate the magnetic anisotropy energy on the different
+unit cell configurations and formulate a possible mechanism that well describes
+the recent experimental observations in $\text{Ta/CoFeB/}\text{HfO}_2$.",2204.11699v1
+2023-11-17,Observation of superconductivity and enhanced upper critical field of $η$-carbide-type oxide Zr${_\mathrm{4}}$Pd$_{\mathrm{2}}$O,"We report the first observation of bulk superconductivity of a
+${\eta}$-carbide-type oxide Zr$_{4}$Pd$_{2}$O. The crystal structure and the
+superconducting properties were studied through synchrotron X-ray diffraction,
+magnetization, electrical resistivity, and specific heat measurement. The
+superconducting transition was observed at $T_{\mathrm{c}}$ = 2.73 K. Our
+measurement revealed that the ${\eta}$-carbide-type oxide superconductor
+Zr$_{4}$Pd$_{2}$O shows an enhanced upper critical field
+${\mu_{\mathrm{0}}H_{\mathrm{c2}}\mathrm{(0)}}$ = 6.72 T, which violates the
+Pauli-Clogston limit ${\mu_{\mathrm{0}}H_{\mathrm{P}}}$ = 5.29 T. On the other
+hand, we found that the enhanced upper critical field is absent in a Rh
+analogue Zr$_{4}$Rh$_{2}$O. The large
+${\mu_{\mathrm{0}}H_{\mathrm{c2}}\mathrm{(0)}}$ of Zr$_{4}$Pd$_{2}$O would be
+raised from strong spin-orbit coupling with Pd-4$d$ electrons. The discovery of
+new superconducting properties for Zr$_{4}$Pd$_{2}$O would shed light on the
+further development of ${\eta}$-carbide-type oxide superconductors.",2311.10338v1
+2023-12-09,Large nonlinear Hall effect and Berry curvature in KTaO3 based two-dimensional electron gas,"The two-dimensional electron gas (2DEG) at oxide interfaces exhibits various
+exotic properties stemming from interfacial inversion symmetry breaking. In
+this work, we report the emergence of large nonlinear Hall effects (NHE) in the
+LaAlO3/KTaO3(111) interface 2DEG under zero magnetic field. Skew scattering was
+identified as the dominant origin based on the cubic scaling of nonlinear Hall
+conductivity with longitudinal conductivity and the threefold symmetry.
+Moreover, a gate-tunable NHE with pronounced peak and dip was observed and
+reproduced by our theoretical calculation. These results indicate the presence
+of Berry curvature hotspots and thus a large Berry curvature triple at the
+oxide interface. Our theoretical calculations confirm the existence of large
+Berry curvatures from the avoided crossing of multiple 5d-orbit bands, orders
+of magnitude larger than that in transition-metal dichalcogenides. NHE offers a
+new pathway to probe the Berry curvature at oxide interfaces, and facilitates
+new applications in oxide nonlinear electronics.",2312.05578v1
+2023-10-19,Coupling of strain and magnetism in manganite-based complex oxide heterostructures,"Complex oxide thin films and heterostructures offer a wide range of
+properties originating from the intrinsic coupling between lattice strain and
+magnetic/electronic ordering. This article reviews experimental,
+phenomenological, and theoretical analyses of the coupling of strain with
+electronic and magnetic properties of mixed valence manganite heterostructures.
+The influence of epitaxial strain on the magnetic properties of manganite films
+is measured using macroscopic magnetization measurements and shown mixed
+reports suggesting, both, an increase and decrease in ferromagnetic phases on
+the application of the strain. Using polarized neutron reflectivity (PNR), a
+simultaneous measurement of transport and magnetic properties of manganite thin
+films showed direct evidence of modification in the magnetic properties on the
+application of bending strain. The coupling coefficient of strain and magnetism
+of manganite heterostructures was estimated using PNR, which not only helped to
+understand the correlation of elastic strain with magnetism but also explained
+the condition of magnetic phase order change in the phase-separated systems
+within a phenomenological Ginzburg Landau theory. An overview is also provided
+of the current perspectives and existing studies on the influence of strain on
+structure, electronic, magnetic, magnetic anisotropy, phase coexistence and
+magnetocaloric properties of mixed valence manganite heterostructures. Based on
+the understanding of a diverse range of perovskite functionalities, detailed
+perspectives on how the coupling of strain and magnetism open up pathways
+toward the emergence of novel device design features including the different
+ways of applying uniform strain, are discussed.",2310.12573v1
+2010-08-02,First-Principles Prediction of Novel Magnetic Materials Based on ZrCuSiAs-like Semiconducting Pnictide-Oxides,"We assumed that significant enlargement of the functional properties of the
+family of quaternary ZrCuSiAs-like pnictide-oxides, often called also as 1111
+phases, which are known now first of all as parent phases for new FeAs
+superconductors, may be achieved by replacement of nonmagnetic ions by magnetic
+ions in semiconducting ZrCuSiAs-like phases. We checked this assumption by
+means of first-principles FLAPW-GGA calculations using a wide-band-gap
+semiconductor YZnAsO doped with Mn, Fe, and Co as an example. Our main finding
+is that substitution of Mn, Fe, and Co for Zn leads to drastic transformations
+of electronic and magnetic properties of the parent material: as distinct from
+the non-magnetic YZnAsO, the examined doped phases YZn0.89Mn0.11AsO,
+YZn0.89Fe0.11AsO, and YZn0.89Co0.11AsO behave as a magnetic semiconductor, a
+magnetic half-metal or as a magnetic gapless semi-metal, respectively.",1008.0250v1
+2010-08-23,Magnetic field dependent specific heat and enhanced Wilson ratio in strongly correlated layered cobalt oxide,"We have investigated the low temperature specific heat properties as a
+function of magnetic field in the strongly correlated layered cobalt oxide
+[BiBa$_{0.66}$K$_{0.36}$O$_2$]CoO$_2$. These measurements reveal two kinds of
+magnetic field dependent contributions in qualitative agreement with the
+presence of a previously inferred magnetic Quantum Critical Point (QCP). First,
+the coefficient of the low temperature T$^3$ behavior of the specific heat
+turns out to sizeably decrease near a magnetic field consistent with the
+critical value reported in a recent paper. In addition, a moderate but
+significant enhancement of the Sommerfeld coefficient is found in the vicinity
+of the QCP suggesting a slight increase of the electronic effective mass. This
+result contrasts with the divergent behavior of the previously reported Pauli
+susceptibility. Thus, a strongly enhanced Wilson ratio is deduced, suggesting
+efficient ferromagnetic fluctuations in the Fermi liquid regime which could
+explain the unusual magnetic field dependent specific heat. As a strong check,
+the high magnetic field Wilson ratio asymptotically recovers the universal
+limit of the local Fermi liquid against ferromagnetism.",1008.3799v1
+2018-11-08,Magnetically-driven orbital-selective insulator-metal transition in double perovskite oxides,"Interaction-driven metal-insulator transitions or Mott transitions
+  are widely observed in condensed-matter systems. In multi-orbital
+  systems, many-body physics is richer in which an orbital-selective
+  metal-insulator transition is an intriguing and unique
+  phenomenon. Here we use first-principles calculations to show that a
+  magnetic transition (from paramagnetic to long-range magnetically
+  ordered) can simultaneously induce an orbital-selective
+  insulator-metal transition in rock-salt ordered double perovskite
+  oxides $A_2BB'$O$_6$ where $B$ is a non-magnetic ion (Y$^{3+}$ and
+  Sc$^{3+}$) and $B'$ a
+  magnetic ion with a $d^3$ electronic configuration (Ru$^{5+}$ and
+  Os$^{5+}$). The orbital selectivity originates from
+  geometrical frustration of a face-centered-cubic lattice on which
+  the magnetic ions $B'$ reside. Including realistic structural
+  distortions and spin-orbit interaction do
+  not affect the transition. The predicted orbital-selective transition
+  naturally explains the anomaly observed in the electric resistivity
+  of Sr$_2$YRuO$_6$. Implications of other available experimental data
+  are also discussed. Our work shows that by exploiting
+  geometrical frustration on non-bipartite lattices, novel
+  electronic/magnetic/orbital-coupled phase transitions can occur in
+  correlated materials that are in the vicinity of metal-insulator phase
+  boundary.",1811.03465v1
+2017-04-26,Magnetic Force Microscopy Characterization of Superparamagnetic Iron Oxide Nanoparticles (SPIONs),"Superparamagnetic iron oxide nanoparticles (SPIONs), due to their
+controllable sizes, relatively long in vivo half-life and limited
+agglomeration, are ideal for biomedical applications such as magnetic labeling,
+hyperthermia cancer treatment, targeted drug delivery and for magnetic
+resonance imaging (MRI) as contrast enhancement agents. In order to understand
+how SPIONs interact with cells and cellular membranes it would be of interest
+to characterize individual SPIONs at the nanoscale in physiologically relevant
+conditions without labeling them. We demonstrate that Magnetic Force Microscopy
+(MFM) can be used to image SPIONs in air as well as in liquid. The magnetic
+properties of bare and SiO2 coated SPIONs are compared using MFM. We report
+that surface modification using (3-mercaptopropyl)-trimethoxysilane
+significantly improves adsorption and distribution of SPIONs on gold surfaces.
+To obtain proof of principle that SPIONS can be imaged with MFM inside the cell
+we imaged SPIONs buried in thin polymer films (polystyrene (PS) and poly
+methyl-methacrylate (PMMA)). This opens the possibility of visualizing SPIONs
+inside the cell without any labeling or modifications and present MFM as a
+potential magnetic analogue for fluorescence microscopy. The results of these
+studies may have a valuable impact for characterization and further development
+of biomedical applications of SPIONs and other magnetic nanoparticles.",1704.08316v1
+2018-10-03,Possible origin of the absence of magnetic order in LiOsO$_3$: Spin-orbit coupling controlled ground state,"LiOsO$_3$ is the first experimentally confirmed polar metal with
+ferroelectric-like distortion. One puzzling experimental fact is its
+paramagnetic state down to very low temperature with negligible magnetic
+moment, which is anomalous considering its $5d^3$ electron configuration since
+other osmium oxides (e.g. NaOsO$_3$) with $5d^3$ Os ions are magnetic. Here the
+magnetic and electronic properties of LiOsO$_3$ are re-investigated carefully
+using the first-principles density functional theory. Our calculations reveal
+that the magnetic state of LiOsO$_3$ can be completely suppressed by the
+spin-orbit coupling. The subtle balance between significant spin-orbit coupling
+and weak Hubbard $U$ of $5d$ electrons can explain both the nonmagnetic
+LiOsO$_3$ and magnetic NaOsO$_3$. Our work provides a reasonable understanding
+of the long-standing puzzle of magnetism in some osmium oxides.",1810.01639v1
+2022-02-07,Chern Number Tunable Quantum Anomalous Hall Effect in Monolayer Transitional Metal Oxides via Manipulating Magnetization Orientation,"Although much effort has been made to explore quantum anomalous Hall effect
+(QAHE) in both theory and experiment, the QAHE systems with tunable Chern
+numbers are yet limited. Here, we theoretically propose that NiAsO$_3$ and
+PdSbO$_3$, monolayer transitional metal oxides, can realize QAHE with tunable
+Chern numbers via manipulating their magnetization orientations. When the
+magnetization lies in the \textit{x-y} plane and all mirror symmetries are
+broken, the low-Chern-number (i.e., $\mathcal{C}=\pm1$) phase emerges. When the
+magnetization exhibits non-zero \textit{z}-direction component, the system
+enters the high-Chern-number (i.e., $\mathcal{C}=\pm3$) phase, even in the
+presence of canted magnetization. The global band gap can approach the
+room-temperature energy scale in monolayer PdSbO$_3$ (23.4 meV), when the
+magnetization is aligned to \textit{z}-direction. By using Wannier-based
+tight-binding model, we establish the phase diagram of magnetization induced
+topological phase transition. Our work provides a high-temperature QAHE system
+with tunable Chern number for the practical electronic application.",2202.02945v2
+2004-06-07,"Electronic self-doping of Mo-states in A2FeMoO6 (A=Ca, Sr and Ba) half-metallic ferromagnets - a Nuclear Magnetic Resonance study","A systematic study of (A,A')2FeMoO6 (A,A'=Ca, Sr, Ba) ferromagnetic oxides
+with double perovskite structure has been performed using 95,97Mo and 57Fe NMR
+spectroscopy. These oxides are isoelectronic but have substantially different
+Curie temperatures. The NMR analysis provides clear evidence that the magnetic
+moment at Mo sites is not constant but varies sensitively with the ionic size
+of the alkaline ions. The 95,97Mo frequency, and thus the electronic charge at
+Mo ions, is found to be smaller in Ba and Ca than in Sr-based oxides. The
+charge release from Mo sites is accompanied by an uptake at Fe sites, and thus
+a self-doping Fe-Mo process is observed. This process is controlled by relevant
+structural parameters: the Fe-O-Mo bond length and bending. A clear
+relationship between the Curie temperature and the magnetic moment and thus
+electron density at Mo sites has been disclosed. The relevance of these
+findings for the understanding of ferromagnetic coupling in double perovskites
+is discussed.",0406161v1
+2006-02-01,Giant Magnetoresistance in an all-oxide spacerless junction,"We report the fabrication of an oxide-specific type of magnetoresistive
+junction, which is a ferromagnetic bilayer. Both electrodes are high
+spin-polarization oxides: magnetite (Fe3O4) and manganite (La0.7Sr0.3MnO3).
+Negligible magnetic coupling between both ferromagnetic electrodes is realised,
+which allows to obtain parallel and antiparallel magnetic configurations of the
+electrodes when sweeping the applied magnetic field. The structure exhibits
+negative giant magnetoresistance (GMR) at low temperatures. This negative MR
+shows that both electrodes stay spin-polarized at the interface and have
+opposite spin polarizations, i.e. the Fe3O4 layer has a negative spin
+polarization at low temperature. Maximum GMR (-5%) is obtained at 55K.",0602017v2
+2007-01-29,Parameters of the Dzyaloshinsky-Moriya type weak ferromagnetism for some perovskite compounds,"Compounds with distorted perovskite structure of the 4-f and 3-d transition
+metals with the common formula LnTO3 (where Ln is rare-earth element, T is an
+element from the Fe group) are the most multifold binary oxides of these two
+groups elements. Wide range of stability for this structure allows the
+realization of combinations of the Lanthanides with all the transition metals
+except the Nickel. Quite interesting physical phenomena take place in these
+oxides like charge and orbital ordering; relatively independent magnetic
+lattices of the both metals; particular magnetic structures; high optical
+indicators; giant magneto-resistance; peculiar dielectric and ferroelectric
+properties etc. We have investigated the magnetic properties of pure ferrites
+and chromium-based materials as well as of some mixed type oxides like
+HoxTb1-xO3, HoMnxFe1-xO3, HoMnxCr1-xO3 and DyFexCr1-xO3.",0701708v1
+2008-10-02,Structural phase stability and Magnetism in Co2FeO4 spinel oxide,"We report a correlation between structural phase stability and magnetic
+properties of Co2FeO4 spinel oxide. We employed mechanical alloying and
+subsequent annealing to obtain the desired samples. The particle size of the
+samples changes from 25 nm to 45 nm. The structural phase separation of
+samples, except sample annealed at 9000C, into Co rich and Fe rich spinel phase
+has been examined from XRD spectrum, SEM picture, along with EDAX spectrum, and
+magnetic measurements. The present study indicated the ferrimagnetic character
+of Co2FeO4, irrespective of structural phase stability. The observation of
+mixed ferrimagnetic phases, associated with two Curie temperatures at TC1 and
+TC2 (>TC1), respectively, provides the additional support of the splitting of
+single cubic spinel phase in Co2FeO4 spinel oxide.",0810.0449v1
+2009-05-26,Compensated magnetism by design in double perovskite oxides,"Taking into account Goodenough's superexchange rules, including both full
+structural relaxation and spin-orbit coupling, and checking strong correlation
+effects, we look for compensated half metals within the class of oxide double
+perovskites materials. Identifying likely half metallic (or half semimetallic)
+antiferromagnets, the full complications including orbital magnetism are
+included in order to arrive at realistic predictions of designed magnetic
+compounds with (near) vanishing net moment. After sorting through several
+candidates that have not been considered previously, two materials,
+K$_2$MnRhO$_6$ and La$_2$CrWO$_6$, remain as viable candidates. An important
+factor is obtaining compounds either with very small induced orbital moment
+(helped by closed subshells) or with an orbital moment that compensates the
+spin-orbit driven degradation of half metallic character. While thermodynamic
+stability of these materials cannot be ensured, the development of
+layer-by-layer oxide deposition techniques does not require that materials be
+thermodynamically stable to be synthesized.",0905.4199v1
+2009-06-18,Magnetic Pyrochlore Oxides,"Within the past 20 years or so, there has occurred an explosion of interest
+in the magnetic behavior of pyrochlore oxides of the type
+$A_{2}^{3+}$$B_{2}^{4+}$O$_{7}$ where $A$ is a rare-earth ion and $B$ is
+usually a transition metal. Both the $A$ and $B$ sites form a network of
+corner-sharing tetrahedra which is the quintessential framework for a
+geometrically frustrated magnet. In these systems the natural tendency to form
+long range ordered ground states in accord with the Third Law is frustrated,
+resulting in some novel short range ordered alternatives such as spin glasses,
+spin ices and spin liquids and much new physics. This article attempts to
+review the myriad of properties found in pyrochlore oxides, mainly from a
+materials perspective, but with an appropriate theoretical context.",0906.3661v1
+2010-10-05,Large bias-dependent magnetoresistance in all-oxide magnetic tunnel junctions with a ferroelectric barrier,"All-oxide magnetic tunnel junctions (MTJs) incorporating functional materials
+as insulating barriers have the potential of becoming the founding technology
+for novel multi-functional devices. We investigate, by first-principles density
+functional theory, the bias-dependent transport properties of an all-oxide
+SrRuO3/BaTiO3/SrRuO3 MTJ. This incorporates a BaTiO3 barrier which can be found
+either in a non-ferroic or in a ferroelectric state. In such an MTJ not only
+can the tunneling magnetoresistance reach enormous values, but also, for
+certain voltages, its sign can be changed by altering the barrier electric
+state. These findings pave the way for a new generation of
+electrically-controlled magnetic sensors.",1010.0902v1
+2011-04-22,Electronic structure and bonding properties of cobalt oxide in the spinel structure,"The spinel cobalt oxide Co3O4 is a magnetic semiconductor containing cobalt
+ions in Co2+ and Co3+ oxidation states. We have studied the electronic,
+magnetic and bonding properties of Co3O4 using density functional theory (DFT)
+at the Generalized Gradient Approximation (GGA), GGA+U, and PBE0 hybrid
+functional levels. The GGA correctly predicts Co3O4 to be a semiconductor, but
+severely underestimates the band gap. The GGA+U band gap (1.96 eV) agrees well
+with the available experimental value (~ 1.6 eV), whereas the band gap obtained
+using the PBE0 hybrid functional (3.42 eV) is strongly overestimated. All the
+employed exchange-correlation functionals predict 3 unpaired d electrons on the
+Co2+ ions, in agreement with crystal field theory, but the values of the
+magnetic moments given by GGA+U and PBE0 are in closer agreement with the
+experiment than the GGA value, indicating a better description of the cobalt
+localized d states. Bonding properties are studied by means of Maximally
+Localized Wannier Functions (MLWFs). We find d-type MLWFs on the cobalt ions,
+as well as Wannier functions with the character of sp3d bonds between cobalt
+and oxygen ions. Such hybridized bonding states indicate the presence of a
+small covalent component in the primarily ionic bonding mechanism of this
+compound.",1104.4383v1
+2011-05-06,The interplay between dopants and oxygen vacancies in the magnetism of V-doped TiO2,"Density functional theory calculations indicate that the incorporation of V
+into Ti lattice positions of rutile TiO2 leads to magnetic V4+ species, but the
+extension and sign of the coupling between dopant moments confirm that
+ferromagnetic order cannot be reached via low-concentration doping in the
+non-defective oxide. Oxygen vacancies can introduce additional magnetic
+centres, and we show here that one of the effects of vanadium doping is to
+reduce the formation energies of these defects. In the presence of both V
+dopants and O vacancies all the spins tend to align with the same orientation.
+We conclude that V doping favours the ferromagnetic behaviour of TiO2 not only
+by introducing spins associated with the dopant centres but also by increasing
+the concentration of oxygen vacancies with respect to the pure oxide.",1105.1289v1
+2013-02-22,Gigantic magnetic field polarization and magnetoelectric coupling in a ferrimagnetic oxide CaBaCo4O7,"The single crystal study of CaBaCo4O7, a non collinear ferrimagnet (TC=64K),
+with a polar orthorhombic space group (Pbn21) between 4 K and 293 K, shows the
+appearance below TC of a large electric polarization along its c axis, reaching
+17mC.m-2 at 10K. At 62.5K, a magnetic field driven giant variation of
+polarization, P(9T)-P(0T)=8mC.m-2, is observed. Moreover, the present
+magnetoelectric measurements, are fully consistent with the m'm2' magnetic
+point group, strongly supporting that this oxide is also ferrotoroidic. This
+ferrimagnetic oxide, which belongs to the '114' structural family, opens an
+avenue for the search of new magnetoelectrics.",1302.5541v2
+2014-11-24,Plasma cleaning of ITER first mirrors in magnetic field,"To avoid reflectivity losses in ITER optical diagnostic systems, plasma
+sputtering of metallic First Mirrors is foreseen in order to remove deposits
+coming from the main wall (mainly beryllium and tungsten). Therefore plasma
+cleaning has to work on large mirrors (up to a size of 200*300 mm) and under
+the influence of strong magnetic fields (several Tesla). This work presents the
+results of plasma cleaning of aluminium and aluminium oxide (used as beryllium
+proxy) deposited on molybdenum mirrors. Using radio frequency (13.56 MHz) argon
+plasma, the removal of a 260 nm mixed aluminium/aluminium oxide film deposited
+by magnetron sputtering on a mirror (98 mm diameter) was demonstrated. 50 nm of
+pure aluminium oxide were removed from test mirrors (25 mm diameter) in a
+magnetic field of 0.35 T for various angles between the field lines and the
+mirrors surfaces. The cleaning efficiency was evaluated by performing
+reflectivity measurements, Scanning Electron Microscopy and X-ray Photoelectron
+Spectroscopy.",1411.6659v1
+2015-01-22,Coexistence and interconvertibility of ferromagnetic and antiferromagnetic phases in the single crystal of Mn$_3$ single-molecule magnet,"We report the coexistence of ferromagnetic and antiferromagnetic phases in
+the single crystal of Mn$_3$ single-molecule magnet. The coexistent state
+appears within a certain period of time in the progress of either oxidation or
+reduction during a reversible oxidation-reduction process, when the sample is
+exposed in the air (oxygen) or the methyl vapor. We noticed an apparent change
+in the molecular structure, which is also reversible in terms of that the
+methyl group is dropped or added to the molecules during the oxidation or
+reduction. The absence or presence of the methyl group in the molecules exert
+an essential impact upon the intermolecular exchange interaction, and the
+ferromagnetic phase comes from the heterogenous intermolecular bonds between
+pairs of molecules of which one molecule has a methyl group whereas the other
+has lost the methyl group. The reversible change in molecular structure
+suggests the magnetic structure of Mn$_3$ might be designed and modulated at
+molecular scale, which implies Mn$_3$ has a great application potential.",1501.05484v1
+2016-10-21,Spin transport and dynamics in all-oxide perovskite La$_{2/3}$Sr$_{1/3}$MnO$_3$/SrRuO$_3$ bilayers probed by ferromagnetic resonance,"Thin films of perovskite oxides offer the possibility of combining emerging
+concepts of strongly correlated electron phenomena and spin current in magnetic
+devices. However, spin transport and magnetization dynamics in these complex
+oxide materials are not well understood. Here, we experimentally quantify spin
+transport parameters and magnetization damping in epitaxial perovskite
+ferromagnet/paramagnet bilayers of La$_{2/3}$Sr$_{1/3}$MnO$_3$/SrRuO$_3$
+(LSMO/SRO) by broadband ferromagnetic resonance spectroscopy. From the SRO
+thickness dependence of Gilbert damping, we estimate a short spin diffusion
+length of $\lesssim$1 nm in SRO and an interfacial spin-mixing conductance
+comparable to other ferromagnet/paramagnetic-metal bilayers. Moreover, we find
+that anisotropic non-Gilbert damping due to two-magnon scattering also
+increases with the addition of SRO. Our results demonstrate LSMO/SRO as a
+spin-source/spin-sink system that may be a foundation for examining
+spin-current transport in various perovskite heterostructures.",1610.06661v1
+2017-03-22,Coexistence of Interfacial Stress and Charge Transfer in Graphene Oxide based Magnetic Nanocomposites,"In this paper, we establish the existence of both compressive stress and
+charge transfer process in hydrothermally synthesized cobalt ferrite-graphene
+oxide (CoFe2O4/GO) nanocomposites. Transmission electron microscopy (TEM)
+results reveal the decoration of CoFe2O4 nanoparticles on GO sheets. Magnetic
+response of nanocomposites was confirme from superconducting quantum
+interference device (SQUID) magnetometer measurement. Optical properties of
+these nanocomposites were investigated by Raman spectroscopy. Interfacial
+compressive stress involved in this system is evaluated from observed blue
+shift of characteristic G peak of graphene oxide. Increase in full width
+half-maximum ( FWHM) as well as up shift in D and G peaks are clear indicator
+of involvement of charge transfer process between GO sheets and dispersed
+magnetic nanoparticles. The effect of charge transfer process is quantified in
+terms of shifting of Fermi level of these nanocomposites. This is evaluated
+from variation in contact surface potential difference (CPD) using Scanning
+Kelvin probe microscopy (SKPM). XRD spectra of CoFe2O4/GO confirm the
+polycrystalline nature of CoFe2O4 nanoparticles. Lattice strain estimated from
+XRD peaks are correlated to the observed Raman shift.",1703.07545v1
+2009-12-07,High temperature ferromagnetism of Li-doped vanadium oxide nanotubes,"The nature of a puzzling high temperature ferromagnetism of doped
+mixed-valent vanadium oxide nanotubes reported earlier by Krusin-Elbaum et al.,
+Nature 431 (2004) 672, has been addressed by static magnetization, muon spin
+relaxation, nuclear magnetic and electron spin resonance spectroscopy
+techniques. A precise control of the charge doping was achieved by
+electrochemical Li intercalation. We find that it provides excess electrons,
+thereby increasing the number of interacting magnetic vanadium sites, and, at a
+certain doping level, yields a ferromagnetic-like response persisting up to
+room temperature. Thus we confirm the surprising previous results on the
+samples prepared by a completely different intercalation method. Moreover our
+spectroscopic data provide first ample evidence for the bulk nature of the
+effect. In particular, they enable a conclusion that the Li nucleates
+superparamagnetic nanosize spin clusters around the intercalation site which
+are responsible for the unusual high temperature ferromagnetism of vanadium
+oxide nanotubes.",0912.1237v1
+2017-05-08,"Re-entrant spin-glass freezing and magneto-dielectric behavior of Li3NiRuO6, a layered rock-salt related oxide","We report the results of neutron diffraction, ac and dc magnetization,
+heat-capacity, complex permittivity, and pyrocurrent measurements on an oxide,
+Li3NiRuO5, hitherto not paid much attention in the literature, except for a
+previous report on its promising electrochemical performance. We emphasize on
+the following findings: (i) Observation of re-entrant spin-glass behavior; that
+is, this oxide undergoes ferrilmagnetic ordering below 8- K, entering
+spin-glass regime around 12 K. (ii) There is no prominent feature in the
+complex dielectric permittivity (in particular, at the magnetic transitions) in
+the absence of external magnetic field, indicative of the absence of
+ferroelectricity. However, there is a distinct evidence for magneto-dielectric
+(MDE) coupling. The sign of MDE coupling also changes as the sample is cooled
+from ferrimagnetic state to spin-glass regime. (iii) There are pyroelectric
+anomalies in the vicinity of 30-70 K, presumably from thermally stimulated
+depolarization current.",1705.02868v1
+2022-05-12,Electron paramagnetic resonance of alkali metal atoms and dimers on ultrathin MgO,"Electron paramagnetic resonance (EPR) can provide unique insight into the
+chemical structure and magnetic properties of dopants in oxide and
+semiconducting materials that are of interest for applications in electronics,
+catalysis, and quantum sensing. Here, we demonstrate that EPR in combination
+with scanning tunneling microscopy (STM) allows for probing the bonding and
+charge state of alkali metal atoms on an ultrathin magnesium oxide layer on a
+Ag substrate. We observe a magnetic moment of $1\mu_\mathrm{B}$ for Li$_2$,
+LiNa, and Na$_2$ dimers corresponding to spin radicals with a charge state of
+$+1e$. Single alkali atoms have the same charge state and no magnetic moment.
+The ionization of the adsorbates is attributed to charge transfer through the
+oxide to the metal substrate. Our work highlights the potential of EPR-STM to
+provide insight into dopant atoms that are relevant for the control of the
+electrical properties of surfaces and nanodevices.",2205.05998v1
+2023-05-16,Unconventional anomalous Hall effect in epitaxially stabilized orthorhombic Ru$^{3+}$ perovskite thin films,"Complex oxides are mesmerizing material systems to realize multiple physical
+properties and functionalities by integrating different elements in a single
+compound. However, owing to the chemical instability, not all the combinations
+of elements can be materialized despite the intriguing potential expected from
+their magnetic and electronic properties. In this study, we demonstrate an
+epitaxial stabilization of orthorhombic Ru$^{3+}$ perovskite oxides: LaRuO$_3$
+and NdRuO$_3$, and their magnetotransport properties that reflect the
+difference between non-magnetic La$^{3+}$ and magnetic Nd$^{3+}$. Above all, an
+unconventional anomalous Hall effect accompanied by an inflection point in
+magnetoresistance is observed around 1.3 T below 1 K for NdRuO$_3$, which is
+ascribed to topological Hall effect possibly due to a non-coplanar spin texture
+on Nd$^{3+}$ sublattice. These studies not only serve a new testbed for the
+interplay between spin-orbit coupling and Coulomb interaction but also open a
+new avenue to explore topological emergent phenomena in well-studied perovskite
+oxides.",2305.09201v1
+2023-06-02,Copper-based charge transfer multiferroics with a $d^9$ configuration,"Multiferroics are materials with a coexistence of magnetic and ferroelectric
+order allowing the manipulation of magnetism by applications of an electric
+field through magnetoelectric coupling effects. Here we propose an idea to
+design a class of multiferroics with a $d^9$ configuration using the magnetic
+order in copper-oxygen layers appearing in copper oxide high-temperature
+superconductors by inducing ferroelectricity. Copper-based charge transfer
+multiferroics SnCuO2 and PbCuO2 having the inversion symmetry breaking $P4mm$
+polar space group are predicted to be such materials. The active inner s
+electrons in Sn and Pb hybridize with O $2p$ states leading the buckling in
+copper-oxygen layers and thus induces ferroelectricity, which is known as the
+lone pair mechanism. As a result of the $d^9$ configuration, SnCuO2 and PbCuO2
+are charge transfer insulators with the antiferromagnetic ground state of the
+moment on Cu retaining some strongly correlated physical properties of parent
+compounds of copper oxide high-temperature superconductors. Our work reveals
+the possibility of designing multiferroics based on copper oxide
+high-temperature superconductors.",2306.01361v1
+2023-07-23,Ru doping induced spin frustration and enhancement of the room-temperature anomalous Hall effect in La2/3Sr1/3MnO3 films,"In transition-metal-oxide heterostructures, the anomalous Hall effect (AHE)
+is a powerful tool for detecting the magnetic state and revealing intriguing
+interfacial magnetic orderings. However, achieving a larger AHE at room
+temperature in oxide heterostructures is still challenging due to the dilemma
+of mutually strong spin-orbit coupling and magnetic exchange interactions.
+Here, we exploit the Ru doping-enhanced AHE in LSMRO epitaxial films. As the
+B-site Ru doping level increases up to 20 percent, the anomalous Hall
+resistivity at room temperature can be enhanced from nOhmcm to uOhmcm scale. Ru
+doping leads to strong competition between ferromagnetic double-exchange
+interaction and antiferromagnetic super-exchange interaction. The resultant
+spin frustration and spin-glass state facilitate a strong skew-scattering
+process, thus significantly enhancing the extrinsic AHE. Our findings could
+pave a feasible approach for boosting the controllability and reliability of
+oxide-based spintronic devices.",2307.12253v1
+2010-03-29,Ferromagnetism in defect-ridden oxides and related materials,"The existence of high-temperature ferromagnetism in thin films and
+nanoparticles of oxides containing small quantities of magnetic dopants remains
+controversial. Some regard these materials as dilute magnetic semiconductors,
+while others think they are ferromagnetic only because the magnetic dopants
+form secondary ferromagnetic impurity phases such as cobalt metal or magnetite.
+There are also reports in d0 systems and other defective oxides that contain no
+magnetic ions. Here, we investigate TiO2 (rutile) containing 1 - 5% of iron
+cations and find that the room-temperature ferromagnetism of films prepared by
+pulsed-laser deposition is not due to magnetic ordering of the iron. The films
+are neither dilute magnetic semiconductors nor hosts to an iron-based
+ferromagnetic impurity phase. A new model is developed for defect-related
+ferromagnetism which involves a spin-split defect band populated by charge
+transfer from a proximate charge reservoir in the present case a mixture Fe2+
+and Fe3+ ions in the oxide lattice. The phase diagram for the model shows how
+inhomogeneous Stoner ferromagnetism depends on the total number of electrons
+Ntot, the Stoner exchange integral I and the defect bandwidth W; the band
+occupancy is governed by the d-d Coulomb interaction U. There are regions of
+ferromagnetic metal, half-metal and insulator as well as nonmagnetic metal and
+insulator. A characteristic feature of the high-temperature Stoner magnetism is
+an an anhysteretic magnetization curve which is practically temperature
+independent below room temperature. This is related to a wandering
+ferromagnetic axis which is determined by local dipole fields. The
+magnetization is limited by the defect concentration, not by the 3d doping.
+Only 1-2 % of the volume of the films is magnetically ordered.",1003.5558v1
+2018-05-25,Room Temperature Magnetic Order in Air-Stable Ultra-Thin Iron Oxide,"Certain two-dimensional (2D) materials exhibit intriguing properties such as
+valley polarization, ferroelectricity, superconductivity and charge-density
+waves. Many of these materials can be manually assembled into atomic-scale
+multilayer devices under ambient conditions, owing to their exceptional
+chemical stability. Efforts have been made to add a magnetic degree of freedom
+to these 2D materials via defects, but only local magnetism has been achieved.
+Only with the recent discoveries of 2D materials supporting intrinsic
+ferromagnetism have stacked spintronic devices become realistic. Assembling 2D
+multilayer devices with these ferromagnets under ambient conditions remains
+challenging due to their sensitivity to environmental degradation, and magnetic
+order at room temperature is rare in van der Waals materials. Here, we report
+the growth of air-stable ultra-thin epsilon-phase iron oxide crystals that
+exhibit magnetic order at room temperature. These crystals require no
+passivation and can be prepared in large quantity by cost-effective chemical
+vapor deposition (CVD). We find that the epsilon phase, which is energetically
+unfavorable and does not form in bulk, can be easily made in 2D down to a seven
+unit-cell thickness. Magneto-optical Kerr effect (MOKE) magnetometry of
+individual crystals shows that even at this ultrathin limit the epsilon phase
+exhibits robust magnetism with coercive fields of hundreds of mT. These
+measurements highlight the advantages of ultrathin iron oxide as a promising
+candidate towards air-stable 2D magnetism and integration into 2D spintronic
+devices.",1805.10372v1
+2024-02-06,Ultrafast terahertz field control of the emergent magnetic and electronic interactions at oxide interfaces,"Ultrafast electric-field control of emergent electronic and magnetic states
+at oxide interfaces offers exciting prospects for the development of new
+generations of energy-efficient devices. Here, we demonstrate that the
+electronic structure and emergent ferromagnetic interfacial state in epitaxial
+LaNiO3/CaMnO3 superlattices can be effectively controlled using intense
+single-cycle THz electric-field pulses. We employ a combination of
+polarization-dependent X-ray absorption spectroscopy with magnetic circular
+dichroism and X-ray resonant magnetic reflectivity to measure a detailed
+magneto-optical profile and thickness of the ferromagnetic interfacial layer.
+Then, we use time-resolved and temperature-dependent magneto-optical Kerr
+effect, along with transient optical reflectivity and transmissivity
+measurements, to disentangle multiple correlated electronic and magnetic
+processes driven by ultrafast high-field (~1 MV/cm) THz pulses. These processes
+include an initial sub-picosecond electronic response, consistent with
+non-equilibrium Joule heating; a rapid (~270 fs) demagnetization of the
+ferromagnetic interfacial layer, driven by THz-field-induced nonequilibrium
+spin-polarized currents; and subsequent multi-picosecond dynamics, possibly
+indicative of a change in the magnetic state of the superlattice due to the
+transfer of spin angular momentum to the lattice. Our findings shed light on
+the intricate interplay of electronic and magnetic phenomena in this strongly
+correlated material system, suggesting a promising avenue for efficient control
+of two-dimensional ferromagnetic states at oxide interfaces using ultrafast
+electric-field pulses.",2402.04302v1
+2004-08-18,Half-magnetization plateau stabilized by structural distortion in the antiferromagnetic Heisenberg model on a pyrochlore lattice,"Magnetization plateaus, visible as anomalies in magnetic susceptibility at
+low temperatures, are one of the hallmarks of frustrated magnetism. We show how
+an extremely robust half-magnetization plateau can arise from coupling between
+spin and lattice degrees of freedom in a pyrochlore antiferromagnet, and
+develop a detailed symmetry of analysis of the simplest possible scenario for
+such a plateau state. The application of this theory to the spinel oxides
+CdCr2O4 and HgCr2O4, where a robust half magnetization plateau has been
+observed, is discussed.",0408397v1
+2006-09-19,Half-magnetization plateaux in Cr spinels,"Magnetization plateaux, visible as anomalies in magnetic susceptibility at
+low temperatures, are one of the hallmarks of frustrated magnetism. An
+extremely robust half-magnetization plateau is observed in the spinel oxides
+CdCr2O4 and HgCr2O4, where it is accompanied by a substantial lattice
+distortion. We give an overview of the present state experiment for CdCr2O4 and
+HgCr2O4, and show how such a half-magnetization plateau arises quite naturally
+in a simple model of these systems, once coupling to the lattice is taken into
+account.",0609470v1
+2012-12-01,Ab initio calculation of the local magnetic moment in titanium doped zinc oxide with a corrected-band-gap scheme,"The local magnetic moment of Ti:ZnO is calculated from first principles by
+using the corrected-band-gap scheme (CBGS). The results shows that the system
+is magnetic with the magnetization of 0.699 $\mu_B$ per dopant. The origin of
+the local magnetic moment is considered to be the impurity band partially
+occupied by the donor electrons in the conduction band. Further, the impacts of
+applying Hubbard U to Ti-d orbital on the magnetic moment have been
+investigated.",1212.0066v1
+2006-09-20,Elastic and magnetic properties on field-induced Metal-Insulator transition of bilayer manganese oxide $(La_{1-z} Pr_z)_{1.2} Sr_{1.8} Mn_2 O_7$ ($z$=0.6),"The elastic and magnetic properties of a single crystal of 327 bilayer
+manganese oxide $(La_{1-z} Pr_z)_{1.2} Sr_{1.8} Mn_2 O_7$ with $z$=0.6 have
+been investigated by ultrasonic and high-field magnetization measurements. A
+distinct elastic anomaly was observed at low temperatures and in high magnetic
+fields when crossing the phase boundary. A pronounced elastic softening as a
+function of magnetic field ($H$) appears across the boundary of the
+low-temperature magnetic phase below around 40 K, accompanied by a distinct
+hysteresis. In the high field region, however, these elastic constants exhibit
+an increase with increasing a magnetic field in the high-field region. The
+high-field magnetization measurement characterizing the magnetic state
+clarified a strong connection between elastic strains and magnetic moments. The
+new metamagnetic transition was found in the high-field region above 40 K,
+accompanied with no hysteresis. The present results of elastic constants are
+discussed in terms of a coupling effect between elastic strains associated with
+sound waves and relevant magnetic moments, and relevant conduction bands. They
+are explained reasonably in terms of a strong coupling between elastic strains
+and magnetic susceptibility $chi$$_{m}$=$partial$$M$/$partial$$H$.",0609498v1
+2022-11-28,Entropy engineering and tunable magnetic order in the spinel high entropy oxide,"Spinel oxides are an ideal setting to explore the interplay between
+configurational entropy, site selectivity, and magnetism in high entropy
+oxides. In this work we characterize the magnetic properties of the spinel
+(Cr,Mn,Fe,Co,Ni)$_3$O$_4$ and study the evolution of its magnetism as a
+function of non-magnetic gallium substitution. Across the range of compositions
+studied here, from 0% to 40% Ga, magnetic susceptibility and powder neutron
+diffraction measurements show that ferrimagnetic order is robust in the spinel
+HEO. However, we also find that the ferrimagnetic order is highly tunable, with
+the ordering temperature, saturated and sublattice moments, and magnetic
+hardness all varying significantly as a function of Ga concentration. Through
+x-ray absorption and magnetic circular dichroism, we are able to correlate this
+magnetic tunability with strong site selectivity between the various cations
+and the tetrahedral and octahedral sites in the spinel structure. In
+particular, we find that while Ni and Cr are largely unaffected by the
+substitution with Ga, the occupancies of Mn, Co, and Fe are each significantly
+redistributed. Ga substitution also requires an overall reduction in the
+transition metal valence, and this is entirely accommodated by Mn. Finally, we
+show that while site selectivity has an overall suppressing effect on the
+configurational entropy, over a certain range of compositions, Ga substitution
+yields a striking increase in the configurational entropy and may confer
+additional stabilization. Spinel oxides can be tuned seamlessly from the
+low-entropy to the high-entropy regime, making this an ideal platform for
+entropy engineering.",2211.15798v1
+2012-10-05,Rapid Microwave-Assisted Synthesis of Dextran-Coated Iron Oxide Nanoparticles for Magnetic Resonance Imaging,"Currently, magnetic iron oxide nanoparticles are the only nano-sized magnetic
+resonance imaging (MRI) contrast agents approved for clinical use, yet
+commercial manufacturing of these agents has been limited or discontinued.
+Though there is still widespread demand for these particles both for clinical
+use and research, they are difficult to obtain commercially, and complicated
+syntheses make in-house preparation infeasible for most biological research
+labs or clinics. To make commercial production viable and increase
+accessibility of these products, it is crucial to develop simple, rapid, and
+reproducible preparations of biocompatible iron oxide nanoparticles. Here, we
+report a rapid, straightforward microwave-assisted synthesis of
+superparamagnetic dextran-coated iron oxide nanoparticles. The nanoparticles
+were produced in two hydrodynamic sizes with differing core morphologies by
+varying the synthetic method as either a two-step or single step process. A
+striking benefit of these methods is the ability to obtain swift and consistent
+results without the necessity for air, pH, or temperature sensitive techniques;
+therefore, reaction times and complex manufacturing processes are greatly
+reduced as compared to conventional synthetic methods. This is a great benefit
+for cost-effective translation to commercial production. The nanoparticles are
+found to be superparamagnetic and exhibit properties consistent for use in MRI.
+In addition, the dextran coating imparts the water-solubility and
+biocompatibility necessary for in vivo utilization.",1210.1827v1
+2014-11-19,Internally Oxidized Nb3Sn Strands with Fine Grain Size and High Critical Current Density,"Nb3Sn superconducting strands are the most practical conductors to generate
+high magnetic fields (12-16 T), and thus have significant applications in
+nuclear magnetic resonance (NMR), and great potential for fusion reactors and
+particle accelerator magnets. High critical current density (Jc) is a key
+parameter for such applications. Significant efforts towards optimization of
+various factors led to an 80% improvement in Jc from the early 1990s to 2003,
+when the 4.2 K, 12 T non-matrix Jc reached 3000 A/mm2 (corresponding to 5000
+A/mm2 in Nb3Sn layer Jc). However, further efforts over the past decade have
+failed to bring about further increase beyond this level, leading some
+researchers to conclude that the Jc of conventional Nb3Sn strands had reached
+its maximum. Here, however, by applying an internal oxidation method, we reduce
+the grain size by a factor of three and nearly double the 12 T Jc. In this
+method, a Nb3Sn strand is fabricated with Nb-Zr alloy as starting material;
+with oxygen supplied properly via an oxide powder, the Zr atoms in the Nb-Zr
+alloy are internally oxidized, forming fine intra-granular and inter-granular
+ZrO2 particles in Nb3Sn layer, which effectively refine Nb3Sn grain size. At a
+reaction temperature of 625 {\deg}C, grain size down to 20-50 nm (36 nm on
+average) has been achieved. For this sample the 4.2 K, 12 T Nb3Sn layer Jc
+reached 9600 A/mm2.",1411.5397v1
+2017-02-22,Interfacial Multiferroics of TiO2/PbTiO3 Heterostructure Driven by Ferroelectric Polarization Discontinuity,"Novel phenomena appear when two different oxide materials are combined
+together to form an interface. For example, at the interface of LaAlO3/SrTiO3,
+two dimensional conductive states form to avoid the polar discontinuity and
+magnetic properties are found at such interface. In this work, we propose a new
+type of interface between two nonmagnetic and nonpolar oxides that could host a
+conductive state with magnetic properties, where it is the ferroelectric
+polarization discontinuity instead of the polar discontinuity that leads to the
+charge transfer, forming the interfacial conductive or magnetic states. As a
+concrete example, we investigate by first-principles calculations the
+heterostructures made of ferroelectric perovskite oxide PbTiO3 and
+non-ferroelectric polarized oxides TiO2. We show that charge is transferred to
+the interfacial layer forming an interfacial conductive state with
+ferromagnetic ordering that may persist up to room temperature. Especially, the
+strong coupling between bulk ferroelectric polarization and interface
+ferromagnetism represents a new type of magnetoelectric effect, which provides
+an ideal platform for exploring the intriguing interfacial multiferroics. The
+findings here are important not only for fundamental science but also for
+promising applications in nanoscale electronics and spintronics.",1702.06656v1
+2017-04-28,Ferromagnetism and spin-dependent transport at a complex oxide interface,"Complex oxide interfaces are a promising platform for studying a wide array
+of correlated electron phenomena in low-dimensions, including magnetism and
+superconductivity. The microscopic origin of these phenomena in complex oxide
+interfaces remains an open question. Here we investigate for the first time the
+magnetic properties of semi-insulating NdTiO$_3$/SrTiO$_3$ (NTO/STO) interfaces
+and present the first milli-Kelvin study of NTO/STO. The magnetoresistance (MR)
+reveals signatures of local ferromagnetic order and of spin-dependent
+thermally-activated transport, which are described quantitatively by a simple
+phenomenological model. We discuss possible origins of the interfacial
+ferromagnetism. In addition, the MR also shows transient hysteretic features on
+a timescale of ~10-100 seconds. We demonstrate that these are consistent with
+an extrinsic magneto-thermal origin, which may have been misinterpreted in
+previous reports of magnetism in STO-based oxide interfaces. The existence of
+these two MR regimes (steady-state and transient) highlights the importance of
+time-dependent measurements for distinguishing signatures of ferromagnetism
+from other effects that can produce hysteresis at low temperatures.",1704.08828v3
+2017-11-07,Mixing of $t_{2g}$-$e_g$ orbitals in 4d and 5d transition metal oxides,"Using exact diagonalization, we study the spin-orbit coupling and
+interaction-induced mixing between $t_{2g}$ and $e_g$ $d$-orbital states in a
+cubic crystalline environment, as commonly occurs in transition metal oxides.
+We make a direct comparison with the widely used $t_{2g}$ only or $e_g$ only
+model, depending on electronic filling. We consider all electron fillings of
+the $d$-shell and compute the total magnetic moment, the spin, the occupancy of
+each orbital, and the effective spin-orbit coupling strength (renormalized
+through interaction effects) in terms of the bare interaction parameters,
+spin-orbit coupling, and crystal field splitting, focusing on the parameter
+ranges relevant to 4d and 5d transition metal oxides. In various limits we
+provide perturbative results consistent with our numerical calculations. We
+find that the $t_{2g}$-$e_g$ mixing can be large, with up to 20\% occupation of
+orbitals that are nominally ""empty"", which has experimental implications for
+the interpretation of the branching ratio in experiments, and can impact the
+effective local moment Hamiltonian used to study magnetic phases and magnetic
+excitations in transition metal oxides. Our results can aid the theoretical
+interpretation of experiments on these materials, which often fall in a regime
+of intermediate coupling with respect to electron-electron interactions.",1711.02328v2
+2019-01-08,High entropy oxides: An emerging prospect for magnetic rare earth - transition metal perovskites,"It has been shown that oxide ceramics containing multiple transition and/or
+rare-earth elements in equimolar ratios have a strong tendency to crystallize
+in simple single phase structures, stabilized by the high configurational
+entropy. In analogy to the metallic alloy systems, these oxides are denoted
+high entropy oxides (HEOs). The HEO concept allows to access hitherto uncharted
+areas in the multi-element phase diagram. Among the already realized structures
+there is the highly complex class of rare earth - transition element
+perovskites. This fascinating class of materials generated by applying the
+innovative concept of high entropy stabilization provides a new and manyfold
+research space with promise of discoveries of unprecedented properties and
+phenomena. The present study provides a first investigation of the magnetic
+properties of selected compounds of this novel class of materials.
+Comprehensive studies by DC and AC magnetometry are combined with element
+specific spectroscopy in order to understand the interplay between magnetic
+exchange and the high degree of chemical disorder in the systems. We observe a
+predominant antiferromagnetic behavior in the single phase materials, combined
+with a small ferromagnetic contribution possibly stemming from small
+ferromagnetic clusters or configurations in the antiferromagnetic matrix. In
+the long term perspective it is proposed to screen the properties of this
+family of compounds with high throughput methods, including combined
+experimental and theoretical approaches.",1901.02395v2
+2019-04-06,Solution Processed Large-scale Multiferroic Complex Oxide Epitaxy with Magnetically Switched Polarization,"Complex oxides with tunable structures have many fascinating properties,
+though high-quality complex oxide epitaxy with precisely controlled composition
+is still out of reach. Here we have successfully developed solution-based
+single crystalline epitaxy for multiferroic
+(1-x)BiTi(1-y)/2FeyMg(1-y)/2O3-(x)CaTiO3 (BTFM-CTO) solid solution in large
+area, confirming its ferroelectricity at atomic-scale with a spontaneous
+polarization of 79~89uC/cm2. Careful compositional tuning leads to a bulk
+magnetization of ~0.07uB/Fe at room temperature, enabling magnetically induced
+polarization switching exhibiting a large magnetoelectric coefficient of
+2.7-3.0X10-7s/m. This work demonstrates the great potential of solution
+processing in large-scale complex oxide epitaxy and establishes novel
+room-temperature magnetoelectric coupling in epitaxial BTFM-CTO film, making it
+possible to explore a much wider space of composition, phase, and structure
+that can be easily scaled up for industrial applications.",1904.03370v1
+2022-03-02,Emergence of insulating ferrimagnetism and perpendicular magnetic anisotropy in 3d-5d perovskite oxide composite films for insulator spintronic,"Magnetic insulators with strong perpendicular magnetic anisotropy (PMA) play
+a key role in exploring pure spin current phenomena and developing
+ultralow-dissipation spintronic devices, thereby it is highly desirable to
+develop new material platforms. Here we report epitaxial growth of
+La2/3Sr1/3MnO3 (LSMO)-SrIrO3 (SIO) composite oxide films (LSMIO) with different
+crystalline orientations fabricated by sequential two-target ablation process
+using pulsed laser deposition. The LSMIO films exhibit high crystalline quality
+with homogeneous mixture of LSMO and SIO at atomic level. Ferrimagnetic and
+insulating transport characteristics are observed, with the
+temperature-dependent electric resistivity well fitted by Mott
+variable-range-hopping model. Moreover, the LSMIO films show strong PMA.
+Through further constructing all perovskite oxide heterostructures of the
+ferrimagnetic insulator LSMIO and a strong spin-orbital coupled SIO layer,
+pronounced spin Hall magnetoresistance (SMR) and spin Hall-like anomalous Hall
+effect (SH-AHE) were observed. These results illustrate the potential
+application of the ferrimagnetic insulator LSMIO in developing all-oxide
+ultralow-dissipation spintronic devices.",2203.00818v1
+2022-06-07,Non-volatile electric control of spin-orbit torques in an oxide two-dimensional electron gas,"Spin-orbit torques (SOTs) have opened a novel way to manipulate the
+magnetization using in-plane current, with a great potential for the
+development of fast and low power information technologies. It has been
+recently shown that two-dimensional electron gases (2DEGs) appearing at oxide
+interfaces provide a highly efficient spin-to-charge current interconversion.
+The ability to manipulate 2DEGs using gate voltages could offer a degree of
+freedom lacking in the classical ferromagnetic/spin Hall effect bilayers for
+spin-orbitronics, in which the sign and amplitude of SOTs at a given current
+are fixed by the stack structure. Here, we report the non-volatile
+electric-field control of SOTs in an oxide-based Rashba-Edelstein 2DEG. We
+demonstrate that the 2DEG is controlled using a back-gate electric-field,
+providing two remanent and switchable states, with a large resistance contrast
+of 1064%. The SOTs can then be controlled electrically in a non-volatile way,
+both in amplitude and in sign. This achievement in a 2DEG-CoFeB/MgO
+heterostructures with large perpendicular magnetization further validates the
+compatibility of oxide 2DEGs for magnetic tunnel junction integration, paving
+the way to the advent of electrically reconfigurable SOT MRAMS circuits, SOT
+oscillators, skyrmion and domain-wall-based devices, and magnonic circuits.",2206.03068v1
+2023-07-10,Unconventional quantum oscillations and evidence of non-trivial electronic states in quasi-two-dimensional electron system at complex oxide interfaces,"The simultaneous occurrence of electric-field controlled superconductivity
+and spin-orbit interaction makes two-dimensional electron systems (2DES)
+constructed from perovskite transition metal oxides promising candidates for
+the next generation of spintronics and quantum computing. It is, however,
+essential to understand the electronic bands thoroughly and verify the
+predicted electronic states experimentally in these 2DES to advance
+technological applications. Here, we present novel insights into the electronic
+states of the 2DES at oxide interfaces through comprehensive investigations of
+Shubnikov-de Haas oscillations in two different systems: EuO/KTaO$_3$ (EuO/KTO)
+and LaAlO$_3$/SrTiO$_3$ (LAO/STO). To accurately resolve these oscillations, we
+conducted transport measurements in high magnetic fields up to 60 T and low
+temperatures down to 100 mK. For 2D confined electrons at both interfaces, we
+observed a progressive increase of oscillations frequency and cyclotron mass
+with the magnetic field. We interpret these intriguing findings by considering
+the existence of non-trivial electronic bands, for which the $E-k$ dispersion
+incorporates both linear and parabolic dispersion relations. In addition to
+providing experimental evidence for topological-like electronic states in
+KTO-2DES and STO-2DES, the unconventional oscillations presented in this study
+establish a new paradigm for quantum oscillations in 2DES based on perovskite
+transition metal oxides, where the oscillations frequency exhibits quadratic
+dependence on the magnetic field.",2307.04854v2
+2023-11-01,Annealing effects on the magnetic and magnetotransport properties of iron oxide nanoparticles self-assemblies,"In magnetic tunnel junctions based on iron oxide nanoparticles the disorder
+and the oxidation state of the surface spin as well as the nanoparticles
+functionalization play a crucial role in the magnetotransport properties. In
+this work, we report a systematic study of the effects of vacuum annealing on
+the structural, magnetic and transport properties of self-assembled ~10 nm
+Fe3O4 nanoparticles. The high temperature treatment (from 573 to 873 K)
+decomposes the organic coating into amorphous carbon, reducing the electrical
+resistivity of the assemblies by 4 orders of magnitude. At the same time, the
+3Fe2+/(Fe3++Fe2+) ratio is reduced from 1.11 to 0.13 when the annealing
+temperature of the sample increases from 573 to 873 K, indicating an important
+surface oxidation. Although the 2 nm physical gap remains unchanged with the
+thermal treatment, a monotonous decrease of tunnel barrier width was obtained
+from the electron transport measurements when the annealing temperature
+increases, indicating an increment in the number of defects and hot-spots in
+the gap between the nanoparticles. This is reflected in the reduction of the
+spin dependent tunneling, which reduces the interparticle magnetoresistance.
+This work shows new insights about influence of the nanoparticle interfacial
+composition, as well their the spatial arrangement, on the tunnel transport of
+self-assemblies, and evidence the importance of optimizing the nanostructure
+fabrication for increasing the tunneling current without degrading the spin
+polarized current.",2311.00700v1
+2006-01-30,59Co Nuclear Quadrupole Resonance Studies of Superconducting and Non-superconducting Bilayer Water Intercalated Sodium Cobalt Oxides NaxCoO2.yH2O,"We report 59Co nuclear quadrupole resonance (NQR) studies of bilayer water
+intercalated sodium cobalt oxides NaxCoO2.yH2O (BLH) with the superconducting
+transition temperatures, 2 K < T_c <= 4.6 K, as well as a magnetic BLH sample
+without superconductivity. We obtained a magnetic phase diagram of T_c and the
+magnetic ordering temperature T_M against the peak frequency nu_3 59Co NQR
+transition I_z = +- 5/2 <=> +-7/2 and found a dome shape superconducting phase.
+The 59Co NQR spectrum of the non-superconducting BLH shows a broadening below
+T_M without the critical divergence of 1/T_1 and 1/T_2, suggesting an
+unconventional magnetic ordering. The degree of the enhancement of 1/T_1T at
+low temperatures increases with the increase of nu_3 though the optimal
+nu_3~12.30 MHz. In the NaxCoO2.yH2O system, the optimal-T_c superconductivity
+emerges close to the magnetic instability. T_c is suppressed near the phase
+boundary at nu_3~12.50 MHz, which is not a conventional magnetic quantum
+critical point.",0601659v1
+2007-09-17,X-Ray Analysis of Oxygen-induced Perpendicular Magnetic Anisotropy in Pt/Co/AlOx trilayer,"X-ray spectroscopy measurements have been performed on a series of Pt/Co/AlOx
+trilayers to investigate the role of Co oxidation in the perpendicular magnetic
+anisotropy of the Co/AlOx interface. It is observed that high temperature
+annealing modifies the magnetic properties of the Co layer, inducing an
+enhancement of the perpendicular magnetic anisotropy. The microscopic
+structural properties are analyzed via X-ray Absorption Spectroscopy, X-ray
+Magnetic Circular Dichroism and X-ray Photoelectron Spectroscopy measurements.
+It is shown that annealing enhances the amount of interfacial oxide, which may
+be at the origin of a strong perpendicular magnetic anisotropy.",0709.2581v2
+2007-11-02,Origin of ferromagnetic response in diluted magnetic semiconductors and oxides,"This paper reviews the present understanding of the origin of ferromagnetic
+response of diluted magnetic semiconductors and diluted magnetic oxides as well
+as in some nominally magnetically undoped materials. It is argued that these
+systems can be grouped into four classes. To the first belong composite
+materials in which precipitations of a known ferromagnetic, ferrimagnetic or
+antiferromagnetic compound account for magnetic characteristics at high
+temperatures. The second class forms alloys showing chemical nano-scale phase
+separation into the regions with small and large concentrations of the magnetic
+constituent. To the third class belong (Ga,Mn)As, heavily doped p-(Zn,Mn)Te,
+and related semiconductors. In these solid solutions the theory built on p-d
+Zener's model of hole-mediated ferromagnetism and on either the Kohn-Luttinger
+kp theory or the multi-orbital tight-binding approach describes qualitatively,
+and often quantitatively many relevant properties. Finally, in a number of
+carrier-doped DMS and DMO a competition between long-range ferromagnetic and
+short-range antiferromagnetic interactions and/or the proximity of the
+localisation boundary lead to an electronic nano-scale phase separation.",0711.0340v1
+2010-01-15,On Using Magnetic and optical methods to determine the size and characteristics of nanoparticles embedded in oxide semiconductors,"Films of oxides doped with transition metals are frequently believed to have
+magnetic inclusions. Magnetic methods to determine the amount of nanophases and
+their magnetic characteristics are described. The amount of the sample that is
+paramagnetic may also be measured. Optical methods are described and shown to
+be very powerful to determine which defects are also magnetic.",1001.2674v1
+2010-07-27,Magnetic interaction at an interface between manganite and other transition metal oxides,"A general consideration is presented for the magnetic interaction at an
+interface between a perovskite manganite and other transition metal oxides. The
+latter is specified by the electron number $n$ in the $d_{3z^2-r^2}$ level as
+$(d_{3z^2-r^2})^n$. Based on the molecular orbitals formed at the interface and
+the generalized Hund's rule, the sign of the magnetic interaction is rather
+uniquely determined. The exception is when the $d_{3z^2-r^2}$ orbital is
+stabilized in the interfacial manganite layer neighboring to a
+$(d_{3z^2-r^2})^1$ or $(d_{3z^2-r^2})^2$ system. In this case, the magnetic
+interaction is sensitive to the occupancy of the Mn $d_{3z^2-r2}$ orbital. It
+is also shown that the magnetic interaction between the interfacial Mn layer
+and the bulk region can be changed. Manganite-based heterostructures thus show
+a rich magnetic behavior. We also present how to generalize the argument
+including $t_{2g}$ orbitals.",1007.4763v1
+2013-03-14,Magnetic hysteresis loop as a probe to distinguish single layer from many layer graphitic structure,"In this report we have pointed out that magnetic hysteresis loop can be used
+as a probe to distinguish a single layer from a many layer graphitic structure.
+Chemically we have synthesized graphitic oxide (GO) and reduced graphitic oxide
+(RGO) for this investigation. We observe ferromagnetic like hysteresis loops
+for both GO and RGO below a certain applied critical magnetic field and above
+this critical field we observe cross-over of the positive magnetization to
+negative magnetization leading to diamagnetic behaviour. This cross-over is
+more dominant for the case of many layer graphitic structure. Upon annealing of
+GO in air the critical cross-over field decreases and the magnetization
+increases for multilayer graphitic structure. Possible reasons for all these
+observations and phenomena is presented here.",1303.3433v1
+2017-03-29,Thickness dependence and dimensionality effects of charge and magnetic orderings in La1/3Sr2/3FeO3 thin films,"We investigate the thickness effects on charge and magnetic orderings in Fe
+perovskite oxide La1/3Sr2/3FeO3/SrTiO3 thin films by hard x-ray and resonant
+soft x-ray scattering (RSXS) with changing thin film thickness systematically.
+We found that the correlation lengths of the magnetic ordering along the
+in-plane and out-of-plane directions are comparable and proportional to the
+thickness, and shows stronger thickness dependence than those of charge orderg.
+%the thickness dependence of correlation length of charge ordering is smaller
+than that of magnetic orderings. The magnetic ordered states disappear when the
+correlation length of magnetic ordering decreases to that of charge ordering
+through the intrinsic thickness effects. Surface sensitive grazing-incident
+RSXS revealed that the orderings exist even in the surface region, which
+indicates that the observed orderings is not affected by surface effect like
+oxygen vacancies. Critical thickness is in 5-15 nm, which corresponds to 4-11
+antiferromagnetic ordering period. This critical value seems to be common to
+other ferromagnetic oxide thin films.",1703.09995v1
+2017-04-11,Role of polar compensation in interfacial ferromagnetism of LaNiO$_3$/CaMnO$_3$ superlattices,"Polar compensation can play an important role in the determination of
+interfacial electronic and magnetic properties in oxide heterostructures. Using
+x-ray absorption spectroscopy, x-ray magnetic circular dichroism, bulk
+magnetometry, and transport measurements, we find that interfacial charge
+redistribution via polar compensation is essential for explaining the evolution
+of interfacial ferromagnetism in LaNiO$_3$/CaMnO$_3$ superlattices as a
+function of LaNiO$_3$ layer thickness. In insulating superlattices (4 unit
+cells or less of LaNiO$_3$), magnetism is dominated by Ni-Mn superexchange,
+while itinerant electron-based Mn-Mn double-exchange plays a role in thicker
+metallic superlattices. X-ray magnetic circular dichroism and resonant x-ray
+scattering show that Ni-Mn superexchange contributes to the magnetization even
+in metallic superlattices. This Ni-Mn superexchange interaction can be
+explained in terms of polar compensation at the LaNiO$_3$-CaMnO$_3$ interface.
+These results highlight the different mechanisms responsible for interfacial
+ferromagnetism and the importance of understanding compensation due to polar
+mismatch at oxide-based interfaces when engineering magnetic properties.",1704.03163v1
+2019-11-07,Limited role of vortices in transport in highly disordered superconductors near $B_{c2}$,"At finite temperatures and magnetic fields, type-II superconductors in the
+mixed state have a non-zero resistance that is overwhelmingly associated with
+vortex motion. In this work we study amorphous indium oxide films, which are
+thicker than the superconducting coherence length, and show that near $B_{c2}$
+their resistance in the presence of perpendicular and in-plane magnetic fields
+becomes almost isotropic. Up to a linear rescaling of the magnetic fields both
+the equilibrium resistance as well as the non-equilibrium current-voltage
+characteristics are insensitive to magnetic field orientation suggesting that,
+for our superconductors, there is no fundamental difference in transport
+between perpendicular and in-plane magnetic fields. Additionally we show that
+this near-isotropic behavior extends to the insulating phase of amorphous
+indium oxide films of larger disorder strength that undergo a magnetic field
+driven superconductor-insulator transition. This near-isotropic behavior raises
+questions regarding the role of vortices in transport and the origin of
+resistance in thin-film superconductors.",1911.02818v1
+2022-01-06,Large Magnetic-Field-Induced Strain at the Spin-Reorientation Transition in the A-Site Ordered Spinel Oxide LiFeCr4O8,"Sintered samples of a spinel oxide LiFeCr4O8, where Cr3+ and Fe3+ ions have
+localized moments, were found to show a large magnetic-field-induced volume
+increase approaching 500 ppm by applying a magnetic field of 9 T. This large
+volume increase appeared only at around 30 K. At 30 K, a spin-reorientation
+transition from ferrimagnetic to conical order occurs, giving rise to this
+large volume increase. The coexistence of ferrimagnetic and conical phases at
+this transition was found to be important, suggesting that such a large
+magnetic-field-induced volume change can be realized at various magnetic
+transitions in localized magnets with strong spin-lattice coupling.",2201.01897v1
+2023-07-26,Highly Tunable Perpendicular Magnetic Anisotropy and Anisotropic Magnetoresistance in Ru-doped La0.67Sr0.33MnO3 Epitaxial Films,"As a prototypical half-metallic ferromagnet, La0.67Sr0.33MnO3 (LSMO) has been
+extensively studied due to its versatile physical properties and great
+potential in spintronic applications. However, the weak perpendicular magnetic
+anisotropy (PMA) limits the controllability and detection of magnetism in LSMO,
+thus hindering the realization of oxide-based spintronic devices with low
+energy consumption and high integration level. Motivated by this challenge, we
+develop an experimental approach to enhance the PMA of LSMO epitaxial films. By
+cooperatively introducing 4d Ru doping and a moderate compressive strain, the
+maximum uniaxial magnetic anisotropy in Ru-doped LSMO can reach 3.0 to 1E5 J/m3
+at 10 K. Furthermore, we find a significant anisotropic magnetoresistance
+effect in these Ru-doped LSMO films, which is dominated by the strong PMA. Our
+findings offer an effective pathway to harness and detect the orientations of
+magnetic moments in LSMO films, thus promoting the feasibility of oxide-based
+spintronic devices, such as spin valves and magnetic tunnel junctions.",2307.13881v1
+2016-06-30,Surface magnetism of strontium titanate,"SrTiO3 plays a central role in oxide electronics. It is the substrate of
+choice for functional oxide heterostructures based on perovskite-structure
+thin-film stacks, and its surface or interface with a polar oxide such as
+LaAlO3 can become a two-dimensional conductor because of electronic
+reconstruction or the presence of oxygen defects. Inconsistent reports of
+magnetic order in SrTiO3 abound in the literature. Here we report a systematic
+experimental study aimed at establishing how and when SrTiO3 can develop a
+magnetic moment at room temperature. Polished 100, 110 or 111 crystal slices
+from four different suppliers are characterized before and after vacuum
+annealing at 750 {\deg}C, both in single-crystal and powdered form. Impurity
+content is analysed at the surface and in the bulk. Besides the underlying
+intrinsic diamagnetism of SrTiO3, magnetic signals are of three types-a Curie
+law susceptibility due to dilute magnetic impurities at the ppm level, a
+hysteretic, temperature-dependent ferromagnetic impurity contribution, and a
+practically-anhysteretic, defect-related temperature-independent component that
+saturates in about 200 mT. The latter component is intrinsic. It is often the
+largest, reaching 10 Bohr magnetons per nm2 of surface area or more and
+dominating the magnetic response in low fields at room temperature. It is
+associated with defects near the surface, and can be destroyed by treatment
+with Tiron (C6H4Na2O8S2), an electron donor molecule that forms a strong
+complex with titanium at the surface. The origin of this unusual
+high-temperature ferromagnetic-like response is discussed.",1606.09422v1
+2018-04-21,The effect of adding magnetic oxide as grain boundary for HAMR,"Grain-to-grain Curie temperature (Tc) variation in the media reduces
+signal-to-noise ratio due to its contribution in transition jitter noise,
+especially when average grain size is pushing down to increase the area storage
+capacity. A thermally insulating magnetic grain boundary may suppress such
+grain-to-grain Tc variation, especially at small grain size. Here we present an
+experimental study on the effect of adding thermally-insulating magnetic oxide,
+in particular BaFexOy, as part of the grain boundary materials in granular
+FePt-C HAMR media. It is found that the BaFexOy is chemically inert to FePt and
+the chemical ordering of FePt-BaFexOy-C media are similar to that of FePt-C
+meida. By tuning the volume fraction of BaFexOy and C, well-separated FePt
+grains (average grain size = 6.8 nm) surrounded by BaFexOy shell with
+perpendicular Hc above 35 kOe can be obtained. Transmission electron microscopy
+study with chemical analysis shows that the magnetic oxide appears to be
+crystalline and surround the FePt grains with immediate full enclosure.
+Magnetic measurements indicate an effective increase of magnetic grain size at
+temperatures below FePt Curie temperature. Pulsed laser pump-probe measurement
+indicates a measurable reduction of Curie temperature variation for the
+FePt-BaFexOy-C media with carefully comparison with the reference FePt-C media.",1804.07892v1
+2020-04-02,Tunable and Enhanced Rashba Spin-Orbit Coupling in Iridate-Manganite Heterostructures,"Tailoring spin-orbit interactions and Coulomb repulsion are the key features
+to observe exotic physical phenomena such as magnetic anisotropy and
+topological spin texture at oxide interfaces. Our study proposes a novel
+platform for engineering the magnetism and spin-orbit coupling at LaMnO3/SrIrO3
+(3d-5d oxide) interfaces by tuning the LaMnO3 growth conditions which controls
+the lattice displacement and spin-correlated interfacial coupling through
+charge transfer. We report on a tunable and enhanced interface-induced Rashba
+spin-orbit coupling and Elliot-Yafet spin relaxation mechanism in LaMnO3/SrIrO3
+bilayer with change in the underlying magnetic order of LaMnO3. We also
+observed enhanced spin-orbit coupling strength in LaMnO3/SrIrO3 compared to
+previously reported SrIrO3 layers. The X-Ray spectroscopy measurement reveals
+the quantitative valence of Mn and their impact on charge transfer. Further, we
+performed angle-dependent magnetoresistance measurements, which show signatures
+of magnetic proximity effect in SrIrO3 while reflecting the magnetic order of
+LaMnO3. Our work thus demonstrates a new route to engineer the interface
+induced Rashba spin-orbit coupling and magnetic proximity effect in 3d-5d oxide
+interfaces which makes SrIrO3 an ideal candidate for spintronics applications.",2004.00800v1
+2018-08-07,Enhanced magnetic properties in ZnCoAlO caused by exchangecoupling to Co nanoparticles,"Wereport the results of a sequence of magnetisation and magneto-optical
+studies on laser ablated thin films of ZnCoAlO and ZnCoO that contain a small
+amount of metallic cobalt. The results are compared to those expected when all
+the magnetization is due to isolated metallic clusters of cobalt and with an
+oxide sample that is almost free from metallic inclusions. Using a variety of
+direct magnetic measurements and also magnetic circular dichroism we find that
+there is ferromagnetism within both the oxide and the metallic inclusions, and
+furthermore that these magnetic components are exchange-coupled when aluminium
+is included. This enhances both the coercive field and the remanence. Hence the
+presence of a controlled quantity of metallic nanoparticles in ZnAlO can
+improve the magnetic response of the oxide, thus giving great advantages for
+applications in spintronics.",1808.02269v1
+2022-03-15,Free-spin dominated magnetocaloric effect in dense Gd$^{3+}$ double perovskites,"Frustrated lanthanide oxides with dense magnetic lattices are of fundamental
+interest for their potential in cryogenic refrigeration due to a large ground
+state entropy and suppressed ordering temperatures, but can often be limited by
+short-range correlations. Here, we present examples of frustrated fcc oxides,
+Ba$_2$GdSbO$_6$ and Sr$_2$GdSbO$_6$ and the new site-disordered analog
+Ca$_2$GdSbO$_6$ ([CaGd]$_A$[CaSb]$_B$O$_6$), in which the magnetocaloric effect
+is influenced by minimal superexchange ($J_1 \sim 10$ mK). We report on the
+crystal structures using powder x-ray diffraction and the bulk magnetic
+properties through low-field susceptibility and isothermal magnetization
+measurements. The Gd compounds exhibit a magnetic entropy change of up to -15.8
+J/K/mol$_\textrm{Gd}$ in a field of 7 T at 2 K, a 20 % excess compared to the
+value of -13.0 J/K/mol$_\textrm{Gd}$ for a standard in magnetic refrigeration,
+Gd$_3$Ga$_5$O$_{12}$. Heat capacity measurements indicate a lack of magnetic
+ordering down to 0.4 K for Ba$_2$GdSbO$_6$ and Sr$_2$GdSbO$_6$, suggesting
+cooling down through the liquid 4-He regime. A mean-field model is used to
+elucidate the role of primarily free spin behavior in the magnetocaloric
+performance of these compounds in comparison to other top-performing Gd-based
+oxides. The chemical flexibility of the double perovskites raises the
+possibility of further enhancement of the magnetocaloric effect in the
+Gd$^{3+}$ fcc lattices.",2203.08214v1
+2022-05-31,Engineering of Heterostructure Pt/Co/AlOx for the enhancement of Dyzaloshinskii-Moria interaction,"The interfacial Dyzaloshinskii-Moria interaction (DMI) helps to stabilize
+chiral domain walls and magnetic skyrmions, which will facilitate new magnetic
+memories and spintronics logic devices. The study of interfacial DMI in
+perpendicularly magnetized structurally asymmetric heavy metal (HM) /
+ferromagnetic (FM) multilayer systems is of high importance due to the
+formation of chiral magnetic textures in the presence of DMI. Here, we report
+the impact of the cobalt oxidation at the cobalt -aluminum oxide interface in
+Pt/Co/AlOx trilayer structure on the DMI by varying the post-growth annealing
+time and Aluminum thickness. For quantifying DMI, we employed magneto-optical
+imaging of asymmetric domain wall expansion, hysteresis loop shift, and
+spin-wave spectroscopy techniques. We further correlated the Cobalt oxidation
+with low-temperature Hall effect measurements and X-ray photoelectron
+spectroscopy. Our results emphasize the characterization of magnetic films for
+MRAM technologies semiconductor temperature process window, where magnetic
+interaction will be critical for device performance.",2205.15940v1
+2022-08-29,Room temperature spin-orbit torque efficiency and magnetization switching in SrRuO3-based heterostructures,"Spin-orbit torques (SOTs) from transition metal oxides (TMOs) in conjunction
+with magnetic materials have recently attracted tremendous attention for
+realizing high-efficient spintronic devices. SrRuO3 is a promising candidate
+among TMOs due to its large and tunable SOT-efficiency as well as high
+conductivity and chemical stability. However, a further study for benchmarking
+the SOT-efficiency and realizing SOT-driven magnetization switching in SrRuO3
+is still highly desired so far. Here, we systematically study the SOT
+properties of high-quality SrRuO3 thin film heterostructuring with different
+magnetic alloys of both IMA and PMA configuration by the harmonic Hall voltage
+technique. Our results indicate that SrRuO3 possesses pronounced SOT-efficiency
+of about 0.2 at room temperature regardless of the magnetic alloys, which is
+comparable to typical heavy metals (HMs). Furthermore, we achieve SOT-driven
+magnetization switching with a low threshold current density of 3.8x10^10
+A/m^2, demonstrating the promising potential of SrRuO3 for practical devices.
+By making a comprehensive comparison with HMs, our work unambiguously
+benchmarks the SOT properties and concludes the advantages of SrRuO3, which may
+bring more diverse choices for SOT applications by utilizing hybrid-oxide/metal
+and all-oxide systems.",2208.13574v1
+2023-07-10,Spin transport properties of spinel vanadate-based heterostructures,"Spin-orbit coupling and breaking of inversion symmetry are necessary
+ingredients to enable a pure spin current-based manipulation of the
+magnetization via the spin-orbit torque effect. Currently, magnetic insulator
+oxides with non-dissipative characteristics are being explored. When combined
+with non-magnetic heavy metals, known for their large spin-orbit coupling, they
+offer promising potential for energy-efficient spin-orbitronics applications.
+The intrinsic electronic correlations characterizing those strongly correlated
+oxides hold the promises to add extra control-knobs to the desired efficient
+spin-wave propagation and abrupt magnetization switching phenomena. Spinel
+vanadate FeV2O4 (FVO) exhibits several structural phase transitions which are
+accompanied by an intricate interplay of magnetic, charge and orbital
+orderings. When grown as a thin film onto SrTiO3, the compressive strain state
+induces a perpendicular magnetic anisotropy, making FVO-based heterostructures
+desirable for spin-orbitronics applications. In this study, we have optimised
+the deposition of stoichiometric and epitaxial Pt/FVO heterostructures by
+Pulsed Laser Deposition and examined their spin-related phenomena. From
+angle-dependent magnetotransport measurements, we observed both Anisotropic
+Magnetoresistance (AMR) and Spin Hall Magnetoresistance (SMR) effects. Our
+findings show the SMR component as the primary contributor to the overall
+magnetoresistance, whose high value of 0.12% is only comparable to properly
+optimized oxide-based systems.",2307.04389v1
+2007-05-03,Electron Doping of Cuprates via Interfaces with Manganites,"The electron doping of undoped high-$T_c$ cuprates via the transfer of charge
+from manganites (or other oxides) using heterostructure geometries is here
+theoretically discussed. This possibility is mainly addressed via a detailed
+analysis of photoemission and diffusion voltage experiments, which locate the
+Fermi level of manganites above the bottom of the upper Hubbard band of some
+cuprate parent compounds. A diagram with the relative location of Fermi levels
+and gaps for several oxides is presented. The procedure discussed here is
+generic, allowing for the qualitative prediction of the charge flow direction
+at several oxide interfaces. The addition of electrons to antiferromagnetic Cu
+oxides may lead to a superconducting state at the interface with minimal
+quenched disorder. Model calculations using static and dynamical mean-field
+theory, supplemented by a Poisson equation formalism to address charge
+redistribution at the interface, support this view. The magnetic state of the
+manganites could be antiferromagnetic or ferromagnetic. The former is better to
+induce superconductivity than the latter, since the spin-polarized charge
+transfer will be detrimental to singlet superconductivity. It is concluded that
+in spite of the robust Hubbard gaps, the electron doping of undoped cuprates at
+interfaces appears possible, and its realization may open an exciting area of
+research in oxide heterostructures.",0705.0498v1
+2013-07-04,Quantum many-body interactions in digital oxide superlattices,"Controlling the electronic properties of interfaces has enormous scientific
+and technological implications and has been recently extended from
+semiconductors to complex oxides which host emergent ground states not present
+in the parent materials. These oxide interfaces present a fundamentally new
+opportunity where, instead of conventional bandgap engineering, the electronic
+and magnetic properties can be optimized by engineering quantum many-body
+interactions. We utilize an integrated oxide molecular-beam epitaxy and
+angle-resolved photoemission spectroscopy system to synthesize and investigate
+the electronic structure of superlattices of the Mott insulator LaMnO3 and the
+band insulator SrMnO3. By digitally varying the separation between interfaces
+in (LaMnO3)2n/(SrMnO3)n superlattices with atomic-layer precision, we
+demonstrate that quantum many-body interactions are enhanced, driving the
+electronic states from a ferromagnetic polaronic metal to a pseudogapped
+insulating ground state. This work demonstrates how many-body interactions can
+be engineered at correlated oxide interfaces, an important prerequisite to
+exploiting such effects in novel electronics.",1307.1475v1
+2013-11-19,Tunneling Electroresistance Induced by Interfacial Phase Transitions in Ultrathin Oxide Heterostructures,"The ferroelectric (FE) control of electronic transport is one of the emerging
+technologies in oxide heterostructures. Many previous studies in FE tunnel
+junctions (FTJs) exploited solely the differences in the electrostatic
+potential across the FTJs that are induced by changes in the FE polarization
+direction. Here, we show that in practice the junction current ratios between
+the two polarization states can be further enhanced by the electrostatic
+modification in the correlated electron oxide electrodes, and that FTJs with
+nanometer thin layers can effectively produce a considerably large
+electroresistance ratio at room temperature. To understand these surprising
+results, we employed an additional control parameter, which is related to the
+crossing of electronic and magnetic phase boundaries of the correlated electron
+oxide. The FE-induced phase modulation at the heterointerface ultimately
+results in an enhanced electroresistance effect. Our study highlights that the
+strong coupling between degrees of freedom across heterointerfaces could yield
+versatile and novel applications in oxide electronics.",1311.4874v1
+2016-02-25,Colossal dielectric constant in high entropy oxides,"Entropic contributions to the stability of solids are very well understood
+and the mixing entropy has been used for forming various solids, for instance
+such as inverse spinels. A particular development was related to high entropy
+alloys in which the configurational disorder is responsible for forming simple
+solid solutions and which are thoroughly studied for various applications
+especially due to their mechanical properties but also electrical properties,
+hydrogen storage, magnetic properties. Many unexplored compositions and
+properties still remain for this class of materials due to their large phase
+space. In a recent report it has been shown that the configurational disorder
+can be used for stabilizing simple solid solutions of oxides, which should
+normally not form solid solutions, these new materials were called
+""entropy-stabilized oxides"". In this pioneering report, it was shown that
+mixing five equimolar binary oxides yielded, after heating at high temperature
+and quenching, an unexpected rock salt structure compound with statistical
+distribution of the cations in a face centered cubic lattice. Following this
+seminal study, we show here that these high entropy oxides (named HEOx
+hereafter) can be substituted by aliovalent elements with a charge compensation
+mechanism. This possibility largely increases the potential development of new
+materials by widening their (already complex) phase space. As a first example,
+we report here that at least one HEOx composition exhibits colossal dielectric
+constants, which could make it very promising for applications as large-k
+dielectric materials.",1602.07842v1
+2016-04-07,Phase transitions via selective elemental vacancy engineering in complex oxide thin films,"Defect engineering has brought about a unique level of control for Si-based
+semiconductors, leading to the optimization of various opto-electronic
+properties and devices. With regard to perovskite transition metal oxides,
+oxygen vacancies have been a key ingredient in defect engineering, as they play
+a central role in determining the crystal field and consequent electronic
+structure, leading to important electronic and magnetic phase transitions.
+Therefore, experimental approaches toward understanding the role of defects in
+complex oxides have been largely limited to controlling oxygen vacancies. In
+this study, we report on the selective formation of different types of
+elemental vacancies and their individual roles in determining the atomic and
+electronic structure of perovskite SrTiO3 (STO) homoepitaxial thin films
+fabricated by pulsed laser epitaxy. Structural and electronic transitions have
+been achieved via selective control of the Sr and oxygen vacancy
+concentrations, respectively, indicating a decoupling between the two phase
+transitions. In particular, oxygen vacancies were responsible for
+metal-insulator transitions, but did not influence the Sr vacancy induced
+cubic-to-tetragonal structural transition in epitaxial STO thin film. The
+independent control of multiple phase transitions in complex oxides by
+exploiting selective vacancy engineering opens up an unprecedented opportunity
+toward understanding and customizing complex oxide thin films.",1604.01875v1
+2021-07-07,Coupling charge and topological reconstructions at polar oxide interfaces,"In oxide heterostructures, different materials are integrated into a single
+artificial crystal, resulting in a breaking of inversion-symmetry across the
+heterointerfaces. A notable example is the interface between polar and
+non-polar materials, where valence discontinuities lead to otherwise
+inaccessible charge and spin states. This approach paved the way to the
+discovery of numerous unconventional properties absent in the bulk
+constituents. However, control of the geometric structure of the electronic
+wavefunctions in correlated oxides remains an open challenge. Here, we create
+heterostructures consisting of ultrathin SrRuO$_3$, an itinerant ferromagnet
+hosting momentum-space sources of Berry curvature, and LaAlO$_3$, a polar
+wide-bandgap insulator. Transmission electron microscopy reveals an atomically
+sharp LaO/RuO$_2$/SrO interface configuration, leading to excess charge being
+pinned near the LaAlO$_3$/SrRuO$_3$ interface. We demonstrate through
+magneto-optical characterization, theoretical calculations and transport
+measurements that the real-space charge reconstruction modifies the
+momentum-space Berry curvature in SrRuO$_3$, driving a reorganization of the
+topological charges in the band structure. Our results illustrate how the
+topological and magnetic features of oxides can be manipulated by engineering
+charge discontinuities at oxide interfaces.",2107.03359v1
+2022-04-13,Oxygen Octahedral Tilt Controlled Topological Hall Effect in Epitaxial and Freestanding SrRuO3/SrIrO3 Heterostructures,"The fabrication technique of freestanding oxide flakes by epitaxial lift-off
+has made significant contributions to the multifunctional oxide thin film
+research. Several highly impactful work have recently demonstrated the
+robustness of freestanding oxide flakes retaining their desirable properties
+after detachment from the substrate by dissolving away the water-soluble
+Sr3Al2O6 buffer layer. Firstly, in epitaxial SrRuO3/SrIrO3 systems showing
+Hall-humps reminiescence of Topological Hall Effect, first-principle
+calculations revealed that octahedral tilts can modify the sign of
+Dzyaloshinskii-Moriya interaction and avoid cancellation in a symmetric
+trilayer structure. Secondly, freestanding flakes of the trilayer is also able
+to retain the Hall-humps across a wide temperature range. The behaviour of
+humps' peak field does not vary with field direction rotation away from surface
+normal, consistent to a micromagnetic simulation result of N\'eel-type magnetic
+Skyrmions. The layer-resolved octahedral tilts in the freestanding
+heterostructures also crucially controls the occurrence of Hall-humps,
+consistent to the insight from the epitaxial ones. This work offers a new
+perspective to understanding Hall-humps in perovskite oxides, as well as
+demonstrates the fabrication of oxide heterostructure membranes with high
+interfacial quality.",2204.06174v2
+2022-11-16,Characterisation of Gamma-irradiated MCz-Silicon Detectors with a High-$K$ Negative Oxide as Field Insulator,"The high-luminosity operation of the Tracker in the Compact Muon Solenid
+(CMS) detector at the Large Hadron Collider (LHC) experiment calls for the
+development of silicon-based sensors. This involves implementation of
+AC-coupling to micro-scale pixel sensor areas to provide enhanced isolation of
+radiation-induced leakage currents. The motivation of this study is the
+development of AC-pixel sensors with negative oxides (such as aluminium oxide -
+Al$_2$O$_3$ and hafnium oxide - HfO$_2$) as field insulators that possess good
+dielectric strength and provide radiation hardness. Thin films of Al$_2$O$_3$
+and HfO$_2$ grown by atomic layer deposition (ALD) method were used as
+dielectrics for capacitive coupling. A comparison study based on dielectric
+material used in MOS capacitors indicate HfO$_2$ as a better candidate since it
+provides higher sensitivity (where, the term sensitivity is defined as the
+ratio of the change in flat-band voltage to dose) to negative charge
+accumulation with gamma irradiation.
+  Further, space charge sign inversion was observed for sensors processed on
+high resistivity p-type Magnetic Czochralski silicon (MCz-Si) substrates that
+were irradiated with gamma rays up to a dose of 1 MGy. The inter-pixel
+resistance values of heavily gamma irradiated AC-coupled pixel sensors suggest
+that high-$K$ negative oxides as field insulators provide a good electrical
+isolation between the pixels.",2211.09158v2
+2023-01-06,APC Nb$_3$Sn superconductors based on internal oxidation of Nb-Ta-Hf alloys,"In the last few years, a new type of Nb$_3$Sn superconducting composite,
+containing a high density of artificial pinning centers (APC) generated via an
+internal oxidation approach, has demonstrated a significantly superior
+performance relative to present, state-of-the-art commercial Nb$_3$Sn
+conductors. This was achieved via the internal oxidation of Nb-4at.%Ta-1at.%Zr
+alloy. On the other hand, our recent studies have shown that internal oxidation
+of Nb-Ta-Hf alloys can also lead to dramatic improvements in Nb$_3$Sn
+performance. In this work we follow up this latter approach, fabricating a
+61-stack APC wire based on the internal oxidation of Nb-4at.%Ta-1at.%Hf alloy,
+and compare its critical current density (Jc) and irreversibility field (Birr)
+with APC wires made using Nb-4at.%Ta-1at.%Zr. A second goal of this work was to
+improve the filamentary design of APC wires in order to improve their wire
+quality and electromagnetic stability. Our new modifications have led to
+significantly improved RRR and stability in the conductors, while still keeping
+non-Cu Jc at or above the FCC Jc specification. Further improvement via
+optimization of the wire recipe and design is ongoing. Finally, additional work
+needed to make APC conductors ready for applications in magnets is discussed.",2301.02571v2
+2023-04-08,Novel entropy-stabilized fluorite oxides with multifunctional properties,"Development of new high-entropy oxides having configurational entropy
+dominating the phase stability has become a hot topic since the discovery of
+rock salt structure entropy-stabilized (ES)(MgCoNiCuZn)O in 2015. Herein, we
+report a set of novel entropy-stabilized fluorite oxides:
+Zr0.2Hf0.2Ce0.2Sn0.2Mn0.2O2-{\delta}, Zr0.2Hf0.2Ti0.2Mn0.2Ce0.2O2-{\delta},
+Zr0.225Hf0.225Ti0.225Mn0.225Ce0.1O2-{\delta}, and
+Zr0.2Hf0.2Ti0.2Mn0.2Ce0.1Ta0.05Fe0.05O2-{\delta} synthesized using standard
+solid-state reaction. These compounds have been investigated using X-ray
+diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy
+techniques to discern their structural, microstructural, and chemical
+properties. The configurational-entropy dominated phase stability and hence the
+entropy stabilization of the compounds is confirmed by cyclic heat treatments.
+The mismatch in the ionic radii and oxidation state of the cations are the key
+factors in achieving a single-phase fluorite structure. Further, screening of
+physical properties including thermal conductivity, optical band gap, magnetic
+properties, and impedance spectroscopy is discussed. Thermal conductivity of
+1.4-1.7 Wm-1K-1 is observed at 300 K and remains mostly invariant across a wide
+temperature range (300K-1073K), favorable for thermal barrier coating
+applications. These ES samples have an optical band gap of 1.6-1.8 eV, enabling
+light absorption across the visible spectrum and hence could be promising for
+photocatalytic applications. The impedance spectroscopy data of the
+entropy-stabilized samples reveal the presence of electronic contributions with
+small activation energy (0.3-0.4 eV) across a temperature range of 298K-423K.
+These observations in ES fluorite systems show potential for their
+multifunctional applications via further optimization and confirm the great
+chemical versatility of entropy-stabilized oxides.",2304.04084v2
+2016-03-14,Magnetic properties of restacked 2D spin $\frac{1}{2}$ honeycomb RuCl$_3$ nanosheets,"Spin $\frac{1}{2}$ honeycomb materials have gained substantial interest due
+to their exotic magnetism and possible application in quantum computing.
+However, in all current materials out-of-plane interactions are interfering
+with the in-plane order, hence a true 2D magnetic honeycomb system is still of
+demand. Here, we report the exfoliation of the magnetic semiconductor
+$\alpha$-RuCl$_3$ into the first halide monolayers and the magnetic
+characterization of the spin $\frac{1}{2}$ honeycomb arrangement of
+turbostratically stacked RuCl$_3$ monolayers. The exfoliation is based on a
+reductive lithiation/hydration approach, which gives rise to a loss of
+cooperative magnetism due to the disruption of the spin $\frac{1}{2}$ state by
+electron injection into the layers. After an oxidative treatment, cooperative
+magnetism similar to the bulk is restored. The oxidized pellets of restacked
+single layers feature a magnetic transition at T$_N$ = 7 K in the in-plane
+direction, while the magnetic properties in the out-of-plane direction vastly
+differ from bulk $\alpha$-RuCl$_3$. The macroscopic pellets of RuCl$_3$
+therefore behave like a stack of monolayers without any symmetry relation in
+the stacking direction. The deliberate introduction of turbostratic disorder to
+manipulate the spin structure of RuCl$_3$ is of interest for research in
+frustrated magnetism and complex magnetic order as predicted by the
+Kitaev-Heisenberg model.",1603.04463v2
+2022-10-04,Bragg diffraction by a magnetic all-in-all-out configuration with application to a cubic cerium pyrochlore oxide,"The Bragg diffraction of neutrons and x-rays are well-suited to the task of
+determining the distribution of magnetization in crystals. Applications of the
+two techniques proceed by contrasting observed intensities with intensities
+calculated with a specific model, and changing the model as need be to achieve
+satisfactory agreement. An all-in-all-out (AIAO) magnetic configuration of
+magnetic dipoles on a cubic face-centred lattice with networks of
+corner-sharing tetrahedra is often mentioned in the context of pyrochlore
+oxides, for example, but the corresponding neutron and x-ray diffraction
+patterns appear not have been calculated. Our results for patterns of Bragg
+spots from an AIAO magnetic configuration defined by a magnetic space group are
+symmetry informed and yield exact reflection conditions. Specifically, a
+long-range order of magnetic dipoles is forbidden in our model. Bulk properties
+arise from higher-order multipoles that include quadrupoles and octupoles.
+Bragg spots that exclude all magnetic multipoles other than an octupole have
+been discovered, and they can be observed by both neutron diffraction and
+resonant x-ray diffraction. All magnetic multipoles allowed in diffraction by
+cerium ions (4f1) are presented in terms of coefficients in a well-documented
+and unusual magnetic ground state. Symmetry of the cerium site in the cubic
+structure constrains the coefficients. Our scattering amplitudes have an
+application in both neutron and x-ray diffraction experiments on Ce2Zr2O7, for
+example, and searches for the sought-after cerium octupole. Also presented for
+future use is a result for the total, energy-integrated magnetic neutron
+scattering intensity by a powder sample.",2210.01449v2
+2023-03-23,Harnessing van der Waals CrPS4 and Surface Oxides for non-monotonic pre-set field induced Exchange Bias in Fe3GeTe2,"Two-dimensional van der Waals (vdW) heterostructures are an attractive
+platform for studying exchange bias due to their defect free and atomically
+flat interfaces. Chromium thiophosphate (CrPS4), an antiferromagnetic material,
+possesses uncompensated magnetic spins in a single layer, rendering it a
+promising candidate for exploring exchange bias phenomena. Recent findings have
+highlighted that naturally oxidized vdW ferromagnetic Fe3GeTe2 exhibits
+exchange bias, attributed to the antiferromagnetic coupling of its ultrathin
+surface oxide layer (O-FGT) with the underlying unoxidized Fe3GeTe2. Anomalous
+Hall measurements are employed to scrutinize the exchange bias within the
+CrPS4/(O-FGT)/Fe3GeTe2 heterostructure. This analysis takes into account the
+contributions from both the perfectly uncompensated interfacial CrPS4 layer and
+the interfacial oxide layer. Intriguingly, a distinct and non-monotonic
+exchange bias trend is observed as a function of temperature below 140 K. The
+occurrence of exchange bias induced by a 'pre-set field' implies that the
+prevailing phase in the polycrystalline surface oxide is ferrimagnetic Fe3O4.
+Moreover, the exchange bias induced by the ferrimagnetic Fe3O4 is significantly
+modulated by the presence of the van der Waals antiferromagnetic CrPS4 layer,
+forming a heterostructure, along with additional iron oxide phases within the
+oxide layer. These findings underscore the intricate and complex nature of
+exchange bias in van der Waals heterostructures, highlighting their potential
+for tailored manipulation and control.",2303.13167v3
+2004-08-26,Further Evidences for Spin Glass like behavior in NiO nanoparticles,"Nickel oxide nanoparticles are prepared by a sol gel method and characterized
+by x-ray diffraction and transmission electron microscope. Here we present
+measurements on temperature and field dependence of magnetization and time
+dependence of thermoremanent magnetization. Our conclusion based on these
+measurements is that the system shows spin glass like behavior.",0408579v1
+2016-04-23,M(H) dependence and size distribution of SPIONs measured by atomic magnetometry,"We demonstrate that the quasistatic recording of the magnetic excitation
+function M(H) of superparamagnetic iron oxide magnetic nanoparticle (SPION)
+suspensions by an atomic magnetometer allows a precise determination of the
+sample's iron mass content mFe and the particle size distribution.",1604.06882v1
+2020-04-24,"Antiferromagnetism in a nanocrystalline high entropy oxide (Co,Cu,Mg,Ni,Zn)O : Magnetic constituents and surface anisotropy leading to lattice distortion","For the first time, this study shows that distortion in a crystal structure
+due to magnetic effect is possible in a lattice with extreme chemical disorder.
+The multicomponent equimolar transition metal oxide (ME TMO),
+(Co,Cu,Mg,Ni,Zn)O, which is a high entropy oxide, has been attracting a lot of
+attention due to its unique application potential in many fields including
+electrochemical energy storage. In the present investigation, nanocrystalline
+ME TMO was synthesised by three bottom up methods. The presence of distortion
+in the rocksalt crystal structure, revealed by X ray diffraction and Raman
+spectroscopy, and correlated with magnetic measurements from SQUID and EPR
+studies could be attributed to the additive effects of exchange striction (from
+the magnetic constituents) and magnetic anisotropy (from the decreased
+crystallite size). For the first time, iron has been doped into ME TMO, to show
+that a higher amount of magnetic constituent increases the distortion in the
+lattice. Nanocrystalline ME TMO also showed a core shell magnetic behavior
+below the bifurcation temperature arising from the uncompensated or canted spin
+at the surface. Neel temperature of the nanocrystalline ME TMO is reported for
+first time to be as high as 700 K. This study helps unravel the structure and
+magnetic properties of such high entropy materials, and augurs a definite scope
+for better understanding of the factors influencing the crystal structure in
+high entropy oxides.",2004.11684v1
+1997-09-03,Polar Jahn-Teller centers and magnetic neutron scattering cross-section in copper oxides,"In the framework of the model of the polar singlet-triplet Jahn-Teller
+centers the cross-section is obtained for magnetic neutron scattering in
+high-$T_{c}$ cuprates. Multi-mode character of the $CuO_{4}$ cluster ground
+manifold in the new phase of polar centers determines the dependence of
+magnetic form-factor on the local structure and charge state of the center. It
+is shown that magnetic inelastic neutron scattering in the system of the polar
+singlet-triplet Jahn-Teller centers permits to investigate the non-magnetic
+charge and structure excitations.",9709033v1
+2006-08-22,The magnetic orders induced ferroelectricity,"We studied the ferroelectricity of magnetic oxides in which its emergence
+coincides with the onset of a second incommensurate magnetic order. We solved
+for the wave function of e_{g} electrons in the presence of magnetic orders.
+The coupling between the magnetic and electric orders is provided by the
+spin-orbit interaction. It was found that the net electric dipole moment of the
+system came from the bond between the transition metal and oxygen atoms. The
+anisotropy of d-orbitals also played an important role. Finally, the form of
+the coupling leads us to the conclusion that it is an improper
+ferroelectricity.",0608470v1
+2006-09-01,Calculations of Magnetic Exchange Interactions in Mott--Hubbard Systems,"An efficient method to compute magnetic exchange interactions in systems with
+strong correlations is introduced. It is based on a magnetic force theorem
+which evaluates linear response due to rotations of magnetic moments and uses a
+novel spectral density functional framework combining our exact diagonalization
+based dynamical mean field and local density functional theories. Applications
+to spin waves and magnetic transition temperatures of 3d metal mono--oxides as
+well as high--T_{c} superconductors are in good agreement with experiment.",0609006v1
+2006-11-26,Strong magnetic scattering from TiO$_{x}$ adhesion layers,"Electronic phase coherence in normal metals is incredibly sensitive to
+magnetic scattering. As a result, the weak localization magnetoresistance and
+time-dependent universal conductance fluctuations are powerful probes of
+magnetic impurities. We report measurements of these effects in Au and Ag
+nanowires with a 1.5 nm thick Ti adhesion layer underneath the deposited metal.
+The results indicate an anomalously large magnetic impurity concentration due
+to the Ti layer. Results suggest that this magnetic scattering and its
+evolution are related to the oxidation state of the Ti.",0611633v1
+2013-10-30,Investigation of MoS2 and Graphene Nanosheets by Magnetic Force Microscopy,"For the first time, the magnetic force microscopy (MFM) is used to
+characterize the mechanically-exfoliated single- and few-layer MoS2 and
+graphene nanosheets. By analysis of the phase and amplitude shifts, the
+magnetic response of MoS2 and graphene nanosheets exhibits the dependence on
+their layer number. However, the solution-processed single-layer MoS2 nanosheet
+shows the reverse magnetic signal to the mechanically-exfoliated one, and the
+graphene oxide nanosheet has not shown any detectable magnetic signal.
+Importantly, graphene and MoS2 flakes become nonmagnetic when they exceed a
+certain thickness.",1310.8172v1
+2014-03-04,Low-temperature magnetism in the honeycomb systems SrLn2O4,"Recent progress in the understanding of the complex magnetic properties of
+the family of rare-earth strontium oxides, SrLn2O4, is reviewed. These
+compounds consisting of hexagons and triangles are affected by geometrical
+frustration and therefore exhibit its characteristic features, such as a
+significant reduction of magnetic ordering temperatures and complex phase
+diagrams in an applied field. Some of the observed features appear to be rather
+remarkable even in the context of the unusual behavior associated with
+geometrically frustrated magnetic systems. Of particular interest is the
+coexistence at the lowest temperature of different magnetic structures
+(exhibiting either long or short-range order) characterized by different
+propagation vectors in materials without significant chemical or structural
+disorder.",1403.0877v1
+2012-04-27,Spin-dependent electron grating effect from helical magnetization in multiferroic tunnel junctions,"In multiferroic oxides with a transverse helical magnetic order, the
+magnetization exchange coupling is sinusoidally space-dependent. We
+theoretically investigate the spin-dependent electron grating effect in
+normal-metal/helical-multiferroic/ferromagnettic heterojunctions. The spin wave
+vector of the spiral can be added or subtracted from the electron spacial wave
+vector inducing spin-conserved and spin-flipped diffracted transmission and
+reflection. The predicted grating effect can be controlled by magnetization
+exchange coupling strength, the helicity spatial period, and the magnetization
+of the ferromagnetic layer.",1204.6095v1
+2019-06-02,Structural and Magnetic Properties of Er3Fe5-xAlxO12 Garnets,"Er3Fe5-xAlxO12 (0.0 < x < 0.8) garnets were prepared by ball milling and
+sintering at 1300 C. Rietveld refinement of the samples revealed a garnet
+structure with Ia3d symmetry. The lattice parameter, cell volume, X-ray density
+and magnetization of the prepared garnets decreased with the increase of Al
+content (x). The coercivity of the garnets increased with x, but remained
+generally low, being below 20 Oe. Low temperature magnetic measurements versus
+temperature indicated that the magnetization of x = 0.0 exhibited a
+compensation temperature at -186 C, however, x = 0.8 exhibited a minimum at a
+higher temperature of -134 C.",1906.00405v1
+1998-07-24,Magnetoresistance of metallic perovskite oxide LaNiO$_{3-δ}$,"We report a study of the magnetoresistance (MR) of the metallic perovskite
+oxide LaNiO$_{3-\delta}$ as a function of the oxygen stoichiometry $\delta$
+($\delta \leq$ 0.14), magnetic field (H $\leq 6T$) and temperature (1.5K $\leq
+$ T $\leq $ 25K). We find a strong dependence of the nature of MR on the oxygen
+stoichiometry. The MR at low temperatures change from positive to negative as
+the sample becomes more oxygen deficient (i.e, $\delta$ increases). Some of the
+samples which are more resistive, show a resistivity minima at $T_{min}$
+$\approx$ 20K. We find that in these samples the MR is positive at T >
+$T_{min}$ and negative for T < $T_{min}$. We conclude that in the absence of
+strong magnetic interaction, the negative MR in these oxides can arise from
+weak localisation effects.",9807330v1
+2002-11-19,Fermi-liquid ground state in n-type copper-oxide superconductor Pr0.91Ce0.09LaCuO4-y,"We report nuclear magnetic resonance studies on the low-doped n-type
+copper-oxide Pr_{0.91}LaCe_{0.09}CuO_{4-y} (T_c=24 K) in the superconducting
+state and in the normal state uncovered by the application of a strong magnetic
+field. We find that when the superconductivity is removed, the underlying
+ground state is the Fermi liquid state. This result is at variance with that
+inferred from previous thermal conductivity measurement and contrast with that
+in p-type copper-oxides with a similar doping level where high-T_c
+superconductivity sets in within the pseudogap phase. The data in the
+superconducting state are consistent with the line-nodes gap model.",0211400v2
+2004-06-29,Ferromagnetism in substituted zinc oxide,"Room-temperature ferromagnetism is observed in (110) oriented ZnO films
+containing 5 at % of Sc, Ti, V, Fe, Co or Ni, but not Cr, Mn or Cu ions. There
+are large moments, 1.9 and 0.5 muB/atom for Co- and Ti-substituted oxides,
+respectively. Sc-substituted ZnO shows also a moment of 0.3 muB/Sc.
+Magnetization is very anisotropic, with variations of up to a factor three
+depending on the orientation of the applied field relative to the R-cut
+sapphire substrates. Results are interpreted in terms of a spin-split donor
+impurity band model, which can account for ferromagnetism in insulating or
+conducting high-k oxides with concentrations of magnetic ions that lie far
+below the percolation threshold. The variation of the ferromagnetism with
+oxygen pressure used during film growth is evidence of a link between
+ferromagnetism and defect concentration.",0406719v1
+2005-02-02,Second Anomaly in the Specific Heat of beta-Pyrochlore Oxide Superconductor KOs2O6,"Resistivity and specific heat have been measured on a single crystalline
+sample of the beta-pyrochlore oxide superconductor, KOs2O6. It is found that a
+second peak in specific heat, which may evidence an unknown phase transition,
+appears around Tp ~ 7.5 K below the superconducting transition temperature Tc =
+9.53 K. Applying magnetic fields up to 14 T, Tc is reduced gradually down to
+7.1 K, while Tp is raised a little and becomes even higher than Tc at 14 T,
+which implies that the second anomaly is not associated directly with the
+superconductivity. It is demonstrated, however, that there is significant
+communication between the two anomalies, suggesting that they come from the
+same electrons. It is also reported that the Sommerfeld coefficient ? in KOs2O6
+is possibly much larger than in other members of beta-pyrochlore oxide
+superconductors, RbOs2O6 (Tc = 6.3 K) and CsOs2O6 (Tc = 3.3 K).",0502043v2
+2005-09-01,Exceptional type-I superconductivity of the layered silver oxide Ag$_5$Pb$_2$O$_6$,"We report zero-resistivity transition and the details of magnetic transition
+of a layered silver oxide Ag$_5$Pb$_2$O$_6$ single crystal, which make
+definitive evidence of superconductivity in this compound. In the AC
+susceptibility of a mono-crystal, we observed large supercooling, as well as
+positive peaks in the real part of the susceptibility indicating the
+reversibility of magnetic process. These observations reveal that
+Ag$_5$Pb$_2$O$_6$ is probably the first oxide that shows type-I
+superconductivity. Evaluation of the superconducting parameters not only gives
+confirming evidence of type-I superconductivity, but also indicates that it is
+a dirty-limit superconductor. We also analyze supercooling to determine the
+upper limit of the Ginzburg-Landau parameter.",0509018v2
+2006-07-03,A second phase transition and superconductivity in the beta-pyrochlore oxide KOs2O6,"Another phase transition that is probably of first order is found in the
+beta-pyrochlore oxide superconductor KOs2O6 with a superconducting transition
+temperature Tc of 9.6 K. It takes place at Tp=7.5 K in the superconducting
+state in a zero magnetic field. By applying magnetic fields of up to 140 kOe,
+the Tc gradually decreased to 5.2 K, while Tp changed little, eventually
+breaking through the Hc2 line at approximately 65 kOe in the H-T diagram. Both
+the normal-state resistivity and Hc2 change slightly but significantly across
+the second phase transition. It is suggested that the transition is associated
+with the rattling of potassium ions located in an oversized cage of osmium and
+oxide ions.",0607064v2
+2007-10-09,Spin ladder compound Pb(0.55)Cd(0.45)V(2)O(5): synthesis and investigation,"The complex oxide Pb(0.55)Cd(0.45)V(2)O(5) was synthesized and investigated
+by means of X-ray powder diffraction, electron diffraction, magnetic
+susceptibility measurements and band structure calculations. Its structure is
+similar to that of MV(2)O(5) compounds (M = Na, Ca) giving rise to a spin
+system of coupled S=1/2 two-leg ladders. Magnetic susceptibility measurements
+reveal a spin gap-like behavior with \Delta ~ 270 K and a spin singlet ground
+state. Band structure calculations suggest Pb(0.55)Cd(0.45)V(2)O(5) to be a
+system of weakly coupled dimers in perfect agreement with the experimental
+data. Pb(0.55)Cd(0.45)V(2)O(5) provides an example of the modification of the
+spin system in layered vanadium oxides by cation substitution. Simple
+correlations between the cation size, geometrical parameters and exchange
+integrals for the MV(2)O(5)-type oxides are established and discussed.",0710.1806v1
+2009-04-28,Oxide layer boron leads to reduced symmetry spin filtering magnetic tunnel junctions,"Experimental studies of FeCoB/MgO/FeCoB tunnel junctions indicate that boron
+diffuses into MgO during rf-sputtering and forms polycrystalline Mg-B-O
+regions. These tunnel junctions provide high tunneling magnetoresistance values
+and low RA products. However the crystal structure of the Mg-B-O region remains
+unknown. Using density functional techniques, I examine three potential Mg(B)
+oxides including Mg$_{2}$B$_{2}$O$_{5}$ (monoclinic and triclinic) and the
+orthorhombic mineral Kotoite (Mg$_3$B$_2$O$_6$). Kotoite is the best candidate
+for formation in magnetic tunnel junctions. The (100) surface of Kotoite has a
+good lattice match with (001) MgO and could template neighboring FeCo into bcc
+layers during annealing. Complex band structure analysis of Kotoite shows that
+the C$_{2v}$ $\tilde{\Delta}_1$ band has a much smaller imaginary k component
+than the C$_{2v}$ $\tilde{\Delta}_4$ band. Based on symmetry analysis, the
+majority spin $\Delta_1$ band in FeCo should couple well with the Kotoite
+$\tilde{\Delta}_1$ band, while the minority FeCo $\Delta_5$ will couple
+partially with the $\tilde{\Delta}_4$ band. Kotoite provides a new route to
+high tunneling magnetoresistance based on spin filtering by a lower symmetry
+oxide region.",0904.4475v1
+2009-08-05,"Synthesis and characterization of ferromagnetic cobalt nanospheres, nanodiscs and nanocubes","We report the synthesis of cobalt nanoparticles with different shapes and
+sizes by rapid pyrolysis of cobalt carbonyl in the presence of various
+surfactants. The size and shape of the nanoparticles were influenced by
+reaction conditions, such as type of the surfactant, molar ratio of surfactant
+to precursor, reflux temperature and reaction time. The shapes that we have
+achieved include spherical, nearly spherical, disc and cube. The presence of
+linear amine yielded nanodiscs and they spontaneously self-assembled into long
+ribbons. The effect of shape anisotropy on magnetic nanoparticles has been
+investigated. Spherical nanoparticles of diameter 14.5 nm show strong
+ferromagnetic behavior at low temperature and superparamagnetism at room
+temperature. On the other hand the cubic nanoparticles of 45 nm sides showed
+negligible coercive field at T = 10 K and ferromagnetism that persisted above T
+= 300 K. The cobalt nanospheres were oxidized to grow cobalt oxide shell of
+varying thickness to study exchange bias effect. A pronounced exchange bias and
+a strong temperature dependant magnetization were observed in oxidized cobalt
+nanospheres.",0908.0665v1
+2009-08-06,Control of magnetism in cobalt nanoparticles by oxygen passivation,"We report on the preparation of ferromagnetic cobalt nanospheres with
+antiferromagnetic oxide capping layer and its implication for the variation in
+magnetic property. The hcp cobalt nanospheres were prepared by thermal
+decomposition of cobalt carbonyl in the presence of organic surfactants. The
+spherical nanoparticles thus prepared were oxidized to grow antiferromagnetic
+layers of varying composition and thickness on top of cobalt spheres. High
+resolution transmission electron microscopy confirmed growth of Co3O4 in one
+case and CoO in another case. Strong exchange anisotropy and enhanced coercive
+field was observed due to the core-shell structure in Co-CoO system. On the
+other hand only a marginal improvement was seen in Co-Co3O4 system. A low
+temperature paramagnetic behavior was also observed that is interpreted in the
+framework of crystal defects in the oxide shell.",0908.0791v1
+2010-08-17,Exchange bias in GeMn nanocolumns: the role of surface oxidation,"We report on the exchange biasing of self-assembled ferromagnetic GeMn
+nanocolumns by GeMn-oxide caps. The x-ray absorption spectroscopy analysis of
+this surface oxide shows a multiplet fine structure that is typical of the Mn2+
+valence state in MnO. A magnetization hysteresis shift |HE|~100 Oe and a
+coercivity enhancement of about 70 Oe have been obtained upon cooling (300-5 K)
+in a magnetic field as low as 0.25 T. This exchange bias is attributed to the
+interface coupling between the ferromagnetic nanocolumns and the
+antiferromagnetic MnO-like caps. The effect enhancement is achieved by
+depositing a MnO layer on the GeMn nanocolumns.",1008.2872v1
+2010-11-23,NaIrO3 - A pentavalent post-perovskite,"Sodium iridium(V) oxide, NaIrO3, was synthesized by a high pressure solid
+state method and recovered to ambient conditions. It is found to be
+isostructural with CaIrO3, the much-studied structural analogue of the
+high-pressure post-perovskite phase of MgSiO3. Among the oxide
+post-perovskites, NaIrO3 is the first example with a pentavalent cation. The
+structure consists of layers of corner- and edge-sharing IrO6 octahedra
+separated by layers of NaO8 bicapped trigonal prisms. NaIrO3 shows no magnetic
+ordering and resistivity measurements show non-metallic behavior. The crystal
+structure, electrical and magnetic properties are discussed and compared to
+known post-perovskites and pentavalent perovskite metal oxides.",1011.5125v2
+2011-05-01,Symmetry and Nonstoichiometry as Possible Origin of Ferromagnetism in Nanoscale oxides,"We show through density functional theory calculations that extended magnetic
+states can inherently occur in oxides as the size of the crystals is reduced
+down to the nanometer scale even when they do not explicitly include intrinsic
+defects. This is because in nanoscale systems crystallographically perfect
+crystallites paradoxically result in nonstoichiometric compositions owing to
+the finite number of constituting atoms. In these structurally perfect but
+stoichiometrically imperfect nanocrystallites, the spin-triplet state is found
+to be more stable than the spin-singlet state, giving rise to an extended spin
+distribution that expands over the entire crystal. According to this picture,
+long-range magnetic order arises from the combined effect of crystal symmetry
+and nonstoichiometry that can coexist exclusively in nanoscale systems. The
+idea can also give reasonable explanations for the unprecedented ferromagnetic
+features observed commonly in nanoscale oxides, including ubiquity, anisotropy,
+and diluteness.",1105.0171v1
+2011-10-31,Spin-dependent recombination in Czochralski silicon containing oxide precipitates,"Electrically detected magnetic resonance is used to identify recombination
+centers in a set of Czochralski grown silicon samples processed to contain
+strained oxide precipitates with a wide range of densities (~ 1e9 cm-3 to ~
+7e10 cm-3). Measurements reveal that photo-excited charge carriers recombine
+through Pb0 and Pb1 dangling bonds and comparison to precipitate-free material
+indicates that these are present at both the sample surface and the oxide
+precipitates. The electronic recombination rates vary approximately linearly
+with precipitate density. Additional resonance lines arising from iron-boron
+and interstitial iron are observed and discussed. Our observations are
+inconsistent with bolometric heating and interpreted in terms of spin-dependent
+recombination. Electrically detected magnetic resonance is thus a very powerful
+and sensitive spectroscopic technique to selectively probe recombination
+centers in modern photovoltaic device materials.",1110.6727v1
+2013-12-03,Reconsidering the possibility of room temperature ferromagnetism in Mn doped Zirconium oxide,"The possibility to induce long range ferromagnetic order by doping oxides
+with transition metal ions has become a very exciting challenge in the last
+decade. Theoretically, it has been claimed that Mn doped ZrO$_2$ could be a
+very promising spintronic candidate and that high critical temperatures could
+be already achieved even for a low Mn concentration. Some experiments have
+reported room temperature ferromagnetism (RT-FM) whilst some others only
+paramagnetism. When observed, the nature of RT-FM appears to be controversial
+and not clearly understood. In this study, we propose to clarify and shed light
+on some of theses existing issues. A detailed study of the critical
+temperatures and low energy magnetic excitations in Mn doped ZrO$_2$ is
+performed. We show that the Curie temperatures were largely overestimated
+previously, due to the inadequate treatment of both thermal and transverse
+fluctuations, and disorder. It appears that the Mn-Mn couplings can not explain
+the observed RT-FM. We argue, that this can be attributed to the interaction
+between large moments induced in the vicinity of the manganese. This is similar
+to the non-magnetic defect induced ferromagnetism reported in oxides,
+semiconductors and graphene/graphite.",1312.0808v1
+2014-02-06,Bi containing multiferroic perovskite oxide thin films,"In this work multiferroic thin films of Bi containing perovskite oxides are
+discussed, where the driving force for ferroelectricity are the Bi3+ lone-pair
+electrons. First, a brief introduction of Bi containing multiferroic perovskite
+oxides will be presented to describe the mechanisms for establishing magnetic
+and ferroelectric order in these compounds and some recent developments in this
+field of research are reported. The second section addresses experimental
+aspects of epitaxial thin film growth of BiMnO3, (Bi0.9La0.1)2NiMnO6 (BLNMO)
+and BiFeO3 thin films by pulsed laser deposition. The third section is
+dedicated to the physical properties of such films in terms of structural
+characterization and the magnetic and ferroelectric properties and their
+correlations in form of magnetoelectric coupling (MEC).",1402.1442v2
+2015-01-16,"Spectroscopic Studies of Iron-based Superconductors, Multi-ferroic Oxides and Double-perovskite: Phonons, Electronic and Spin Excitations","Raman spectroscopy is a very powerful probe to study the nature of
+quasi-particle excitations in condensed matter physics. The work presented in
+this thesis is focused on two different families of novel materials, namely the
+iron-based superconductors (FeBS), multiferroic oxides and double perovskite.
+Although the properties of these two systems are quite different, some
+comparison can still be drawn between them. For instance, in both of these
+systems magnetism plays a crucial role and intricate coupling between phononic,
+magnetic and orbital degrees of freedom is crucial to understand their
+underlying physics responsible for their various exotic physical properties.
+Understanding the microscopic origin of quasi-particle excitations, such as
+phonons, magnons, orbitons, plasmons etc., and coupling between them in these
+complex materials, has been an intense field of research because it is believed
+that these excitations hold the key for explaining their rich physics. The
+systems studied in the thesis include (A) FeBS - (i) FeSe0.82 (ii)
+Ce1-zYzFeAsO1-xFx (z = 0, 0.4; x = 0.1, 0.2) (iii) Ca4Al2O5.7Fe2As2 (iv)
+Ca(Fe1-xCox)2As2 (x = 0.03, 0.05). (B) Multiferroic oxides - (i) AlFeO3 (ii)
+TbMnO3 and double perovskite (iii) La2NiMnO6.",1501.04055v1
+2015-05-19,Pair breaking in multi-orbital superconductors: an application to oxide interfaces,"We investigate the impact of impurity scattering on superconductivity in an
+anisotropic multi-orbital model with spin-orbit coupling which describes the
+electron fluid at two-dimensional oxide interfaces. As the pairing mechanism is
+under debate, both conventional and unconventional superconducting states are
+analyzed. We consider magnetic and nonmagnetic spin-dependent intra- and
+interorbital scattering and discuss possible microscopic realizations leading
+to these processes. It is found that, for magnetic disorder, the unconventional
+superconductor is protected against interband scattering and, thus, more robust
+than the conventional condensate. In case of nonmagnetic impurities, the
+conventional superconductor is protected as expected from the Anderson theorem
+and the critical scattering rate of the unconventional state is enhanced by a
+factor of four due to the spin-orbit coupling and anisotropic masses in oxide
+interfaces.",1505.04919v1
+2015-11-23,Structure and ferromagnetic instability of the oxygen-deficient SrTiO$_3$ surface,"SrTiO$_3$ (STO) is the substrate of choice to grow oxide thin-films and oxide
+heterojunctions, which can form quasi-two-dimensional electronic phases that
+exhibit a wealth of phenomena, and, thus, a workhorse in the emerging field of
+metal-oxide electronics. Hence, it is of great importance to know the exact
+character of the STO surface itself under various oxygen environments. Using
+density functional theory within the spin generalized gradient approximation we
+have investigated the structural, electronic and magnetic properties of the
+oxygen-deficient STO surface. We find that the surface oxygen vacancies order
+in periodic arrays giving rise to surface magnetic moments and a quasi
+two-dimensional electron gas in the occupied Ti 3-d orbitals. The surface
+confinement, the oxygen-vacancy ordering, and the octahedra distortions give
+rise to spin-polarized $t_{2g}$ dispersive sub-bands; their energy split near
+the Brillouin zone center acts as an effective Zeeman term, which, when we turn
+on a Rashba interaction, produces bands with momentum-spin correlations similar
+to those recently discovered on oxygen deficient STO surface.",1511.07495v1
+2016-06-30,Tunneling into a quantum confinement created by a single-step nano-lithography of conducting oxide interfaces,"A new nano-lithography technique compatible with conducting oxide interfaces,
+which requires a single lithographic step with no additional amorphous layer
+deposition or etching, is presented. It is demonstrated on SrTiO3/LaAlO3
+interface where a constriction is patterned in the electron liquid. We find
+that an additional back-gating can further confine the electron liquid into an
+isolated island. Conductance and differential conductance measurements show
+resonant tunneling through the island. The data at various temperatures and
+magnetic fields are analyzed and the effective island size is found to be of
+the order of 10nm. The magnetic field dependence suggests absence of spin
+degeneracy in the island. Our method is suitable for creating superconducting
+and oxide-interface based electronic devices.",1606.09340v1
+2017-01-23,"Time-reversal symmetry breaking hidden order in Sr$_2$(Ir,Rh)O$_4$","Layered 5$d$ transition iridium oxides, Sr$_2$(Ir,Rh)O$_4$, are described as
+unconventional Mott insulators with strong spin-orbit coupling. The undoped
+compound, Sr$_2$IrO$_4$, is a nearly ideal two-dimensional pseudospin-$1/2$
+Heisenberg antiferromagnet, similarly to the insulating parent compound of
+high-temperature superconducting copper oxides. Using polarized neutron
+diffraction, we here report a hidden magnetic order in pure and doped
+Sr$_2$(Ir,Rh)O$_4$, distinct from the usual antiferromagnetic pseudo-spin
+ordering. We find that time-reversal symmetry is broken while the lattice
+translation invariance is preserved in the hidden order phase. The onset
+temperature matches that of the odd-parity hidden order recently highlighted
+using optical second harmonic generation experiments. The novel magnetic order
+and broken symmetries can be explained by the loop-current model, previously
+predicted for the copper oxide superconductors.",1701.06485v1
+2012-04-13,NO-assisted molecular-beam epitaxial growth of nitrogen substituted EuO,"We have investigated a method for substituting oxygen with nitrogen in EuO
+thin films, which is based on molecular beam epitaxy distillation with NO gas
+as the oxidizer. By varying the NO gas pressure, we produce crystalline,
+epitaxial EuO_(1-x)N_x films with good control over the films' nitrogen
+concentration. In-situ x-ray photoemission spectroscopy reveals that nitrogen
+substitution is connected to the formation Eu3+ 4f6 and a corresponding
+decrease in the number of Eu2+ 4f7, indicating that nitrogen is being
+incorporated in its 3- oxidation state. While small amounts of Eu3+ in
+over-oxidized Eu_(1-delta)O thin films lead to a drastic suppression of the
+ferromagnetism, the formation of Eu3+ in EuO_(1-x)N_x still allows the
+ferromagnetic phase to exist with an unaffected Tc, thus providing an ideal
+model system to study the interplay between the magnetic f7 (J=7/2) and the
+non-magnetic f6 (J=0) states close to the Fermi level.",1204.2861v1
+2015-12-19,Structural evolution of epitaxial SrCoOx films near topotactic phase transition,"Control of oxygen stoichiometry in complex oxides via topotactic phase
+transition is an interesting avenue to not only modifying the physical
+properties, but utilizing in many energy technologies, such as energy storage
+and catalysts. However, detailed structural evolution in the close proximity of
+the topotactic phase transition in multivalent oxides has not been much
+studied. In this work, we used strontium cobaltites (SrCoOx) epitaxially grown
+by pulsed laser epitaxy (PLE) as a model system to study the oxidation-driven
+evolution of the structure, electronic, and magnetic properties. We grew
+coherently strained SrCoO2.5 thin films and performed post-annealing at various
+temperatures for topotactic conversion into the perovskite phase
+(SrCoO3-{\delta}). We clearly observed significant changes in electronic
+transport, magnetism, and microstructure near the critical temperature for the
+topotactic transformation from the brownmillerite to the perovskite phase.
+Nevertheless, the overall crystallinity was well maintained without much
+structural degradation, indicating that topotactic phase control can be a
+useful tool to control the physical properties repeatedly via redox reactions.",1512.06167v1
+2015-12-21,"Novel synthesis method of nonstoichiometric Na2-xIrO3. Crystal structure, transport and magnetic properties","Transition metal oxides with 4d or 5d metals are of great interest due to the
+competing interactions, of the Coulomb repulsion and the itineracy of the
+d-electrons, opening a possibility of building new quantum ground states.
+Particularly the 5d metal oxides containing Iridium have received significant
+attention within the last years, due to their unexpected physical properties,
+caused by a strong spin orbit coupling observed in Ir(IV). A prominent example
+is the Mott-insulator Sr2IrO4. Another member of this family, the honeycomb
+lattice compound Na2IrO3, also being a Mott-insulator having, most probably, a
+Kitaev spin liquid ground state. By deintercalating sodium from Na2IrO3, we
+were able to synthesize a new honeycomb lattice compound with more than 50%
+reduced sodium content. The reduction of the sodium content in this layered
+compound leads to a change of the oxidation state of iridium from +IV to +V/+VI
+and a symmetry change from C2/c to P-3. This goes along with significant
+changes of the physical properties. Besides the vanishing magnetic ordering at
+15K, also the transport properties changes and instead insulating
+semiconducting properties are observed.",1512.06627v1
+2016-04-30,Thermal stimulated current response in cupric oxide single crystal thin films over a wide temperature range,"Cupric oxide single crystal thin films were grown by plasma-assisted
+molecular beam epitaxy. X-ray diffraction, Raman spectrum and in situ
+reflection high-energy electron diffraction show that the thin films are 2x2
+reconstructed with an in-plane compression and out-of-plane stretching. Thermal
+stimulated current measurement indicates that the electric polarization
+response presents in the special 2D cupric oxide single crystal thin film over
+a wide temperature range from 130 K to near-room temperature. We infer that the
+abnormal electric response involves the changing of phase transition
+temperature induced by structure distortion, the spin frustration and magnetic
+fluctuation effect of short-range magnetic order, or the combined action of
+both two factors mentioned above. This work suggests a promising clue for
+finding new room temperature single phase multiferroics or tuning phase
+transition temperature.",1605.00109v1
+2016-12-30,Exchange Bias Effects in Iron Oxide-Based Nanoparticle Systems,"The exploration of exchange bias (EB) on the nanoscale provides a novel
+approach to improving the anisotropic properties of magnetic nanoparticles for
+prospective applications in nanospintronics and nanomedicine. However, the
+physical origin of EB is not fully understood. Recent advances in chemical
+synthesis provide a unique opportunity to explore EB in a variety of iron
+oxide-based nanostructures ranging from core/shell to hollow and hybrid
+composite nanoparticles. Experimental and atomistic Monte Carlo studies have
+shed light on the roles of interface and surface spins in these nanosystems.
+This review paper aims to provide a thorough understanding of the EB and
+related phenomena in iron oxide-based nanoparticle systems, knowledge of which
+is essential to tune the anisotropic magnetic properties of exchange-coupled
+nanoparticle systems for potential applications.",1612.09455v1
+2017-11-11,Spin-orbital polarons in electron doped copper oxides,"Present work demonstrates the formation of spin-orbital polarons in electron
+doped copper oxides, that arise due to doping-induced polarisation of the
+oxygen orbitals in the CuO$_2$ planes. The concept of such polarons is
+fundamentally different from previous interpretations. The novel aspect of
+spin-orbit polarons is best described by electrons becoming self-trapped in
+one-dimensional channels created by polarisation of the oxygen orbitals. The
+one-dimensional channels form elongated filaments with two possible
+orientations, along the diagonals of the elementary CuO$_2$ square plaquette.
+As the density of doped electrons increases multiple filaments are formed.
+These may condense into a single percollating filamentary phase. Alternatively,
+the filaments may cross perpendicularly to create an interconnected conducting
+quasi-one-dimensional web. At low electron doping the antiferromagnetic (AFM)
+state and the polaron web coexist. As the doping is increased the web of
+filaments modifies and transforms the AFM correlations leading to a series of
+quantum phase transitions - which affect the normal and superconducting state
+properties.",1711.04164v1
+2017-11-30,Complementary logic operation based on electric-field controlled spin-orbit torques,"Spintronic devices as alternatives to traditional semiconductor-based
+electronic devices attract considerable interest as they offer zero quiescent
+power, built-in memory, scalability, and reconfigurability. To realize
+spintronic logic gates for practical use, a complementary logic operation is
+essential but still missing despite a recent progress in spin-based logic
+devices. Here, we report the development of a complementary spin logic device
+using electric-field controlled spin-orbit torque (SOT) switching. In heavy
+metal/ferromagnet/oxide structures, the critical current for SOT-induced
+switching of perpendicular magnetization is efficiently modulated by an
+electric field via voltage-controlled magnetic anisotropy (VCMA) effect in a
+non-volatile manner. Moreover, the polarity of the VCMA is tuned by the
+modification of oxidation state at the ferromagnet/oxide interface. This allows
+us to fabricate both n-type and p-type spin logic devices and to enable a
+complementary logic operation, paving the way for the development of
+non-volatile and reconfigurable logic devices.",1711.11172v1
+2019-02-26,"Magnetic, electrochemical and thermoelectric properties of $P2 - Na_x(Co_{7/8}Sb_{1/8})O_2$","We theoretically investigated the electronic, electrochemical and magnetic
+properties of Sb doped $Na_xCoO_2$ ($x = 1, 0.75$ and $0.50$). $Sb_{Co}$
+dopants adopt +5 oxidation state in $Na_xCoO_2$ host lattice for all Na
+concentrations ($x$). Due to high oxidation states, $Sb^{5+}$ strongly repels
+Na ions and therefore it decreases the electrochemical potential (vs.
+Na/Na$^+$). The electrons introduced by $Sb^{5+}$ localize on nearby Co ions
+creating $Co^{2+}$ species which are absent in undoped $Na_xCoO_2$. $Co^{2+}$
+ions reduce the spin entropy flow decreasing the Seebeck coefficient in the Sb
+doped compounds. The results can be generalized to other dopants with high
+oxidation state.",1902.09760v1
+2019-08-23,Damping enhancement in coherent ferrite/insulating-paramagnet bilayers,"High-quality epitaxial ferrites, such as low-damping MgAl-ferrite (MAFO), are
+promising nanoscale building blocks for all-oxide heterostructures driven by
+pure spin current. However, the impact of oxide interfaces on spin dynamics in
+such heterostructures remains an open question. Here, we investigate the spin
+dynamics and chemical and magnetic depth profiles of 15-nm-thick MAFO
+coherently interfaced with an isostructural $\approx$1-8-nm-thick overlayer of
+paramagnetic CoCr$_2$O$_4$ (CCO) as an all-oxide model system. Compared to MAFO
+without an overlayer, effective Gilbert damping in MAFO/CCO is enhanced by a
+factor of $>$3, irrespective of the CCO overlayer thickness. We attribute this
+damping enhancement to spin scattering at the $\sim$1-nm-thick chemically
+disordered layer at the MAFO/CCO interface, rather than spin pumping or
+proximity-induced magnetism. Our results indicate that damping in ferrite-based
+heterostructures is strongly influenced by interfacial chemical disorder, even
+if the thickness of the disordered layer is a small fraction of the ferrite
+thickness.",1908.08629v2
+2020-03-27,Perspective: Strongly correlated and topological states in [111] grown transition metal oxide thin films and heterostructures,"We highlight recent advances in the theory, materials fabrication, and
+experimental characterization of strongly correlated and topological states in
+[111] oriented transition metal oxide thin films and heterostructures, which
+are notoriously difficult to realize compared to their [001] oriented
+counterparts. We focus on two classes of complex oxides, with the chemical
+formula ABO3 and A2B2O7, where the B sites are occupied by an open-shell
+transition metal ion with a local moment, and the A sites are typically a rare
+earth. The [111] oriented quasi-two-dimensional lattices derived from these
+parent compound lattices can exhibit peculiar geometries and symmetries,
+namely, a buckled honeycomb lattice, as well as kagome and triangular lattices.
+These lattice motifs form the basis for emergent strongly correlated and
+topological states expressed in exotic magnetism, various forms of orbital
+ordering, topological insulators, topological semimetals, quantum anomalous
+Hall insulators, and quantum spin liquids. For transition metal ions with high
+atomic number, spin-orbit coupling plays a significant role and may give rise
+to additional topological features in the electronic band structure and in the
+spectrum of magnetic excitations. We conclude the Perspective by articulating
+open challenges and opportunities in this actively developing field.",2003.12211v1
+2021-12-22,Neutron Scattering Studies of the Breathing Pyrochlore Antiferromagnet LiGaCr$_{4}$O$_{8}$,"We report neutron scattering measurements of the spinel oxide
+LiGaCr$_{4}$O$_{8}$, in which magnetic ions Cr$^{3+}$ form a breathing
+pyrochlore lattice. Our experiments reveal the coexistence of a nearly
+dispersionless resonance mode and dispersive spin wave excitations in the
+magnetically ordered state, which can be quantitatively described by a quantum
+spin model of hexagonal loops and linear spin wave theory with the same set of
+exchange parameters, respectively. Comparison to other Cr spinel oxides reveals
+a linear relationship between the resonance energy and lattice constant across
+all these materials, which is in agreement with our hexagonal loop
+calculations. Our results suggest a unified picture for spin resonances in Cr
+spinel oxides.",2112.11709v1
+2022-12-23,Surface ferromagnetism in a chiral topological semimetal CoSi,"Despite the chiral topological semimetal CoSi is known as bulk diamagnetic,
+it shows unusual surface ferromagnetism of debatable origin. The ferromagnetic
+ordering has been attributed to the distorted bonds, the superlattice of
+ordered vacancies, or even to topological surface textures due to the spin
+polarization in the neighboring Fermi arcs. We experimentally compare
+magnetization reversal curves for initially oxidized CoSi single crystals and
+cleaved samples with a fresh, oxide-free surface. While the oxidized CoSi
+samples do not show sizable ferromagnetism, the fresh CoSi surface gives a
+strong ferromagnetic response, which is accompanied by the pronounced
+modulation of the angle dependence of magnetization, as it can be expected for
+easy and hard axes in a ferromagnet. In addition to the first order reversal
+curves analysis, this observation allows us to distinguish between different
+mechanisms of the ferromagnetic ordering in CoSi single crystals. We conclude
+that the surface states-induced RKKY interaction between distorted bonds near
+the sample surface is responsible for the strong ferromagnetic multi-domain
+behavior for freshly cleaved samples.",2212.12383v2
+2023-11-15,Thermal Magnetoelectrics in all Inorganic Quasi-Two-Dimensional Halide Perovskites,"From lithium-ion batteries to high-temperature superconductors, oxide
+materials have been widely used in electronic devices. However, demands of
+future technologies require materials beyond oxides, as anion chemistries
+distinct from oxygen can expand the palette of mechanisms and phenomena, to
+achieve superior functionalities. Examples include nitride-based wide bandgap
+semiconductors and halide perovskite solar cells, with MAPbBr3 being a
+representation revolutionizing photovoltaics research. Here, we demonstrate
+magnetoelectric behaviour in quasi-two-dimensional halides (K,Rb)3Mn2Cl7
+through simultaneous thermal control of electric and magnetic polarizations by
+exploiting a polar-to-antipolar displacive transition. Additionally, our
+calculations indicate a possible polarization switching path including a strong
+magnetoelectric coupling, indicating halides can be excellent platforms to
+design future multiferroic and ferroelectric devices. We expect our findings to
+broaden the exploration of multiferroics to non-oxide materials and open access
+to novel mechanisms, beyond conventional electric/magnetic control, for
+coupling ferroic orders.",2311.09324v1
+2023-12-11,Phase transitions of LaMnO$_3$ and SrRuO$_3$ from DFT + U based machine learning force fields simulations,"Perovskite oxides are known to exhibit many magnetic, electronic and
+structural phases as function of doping and temperature. These materials are
+theoretically frequently investigated by the DFT+U method, typically in their
+ground state structure at $T=0$. We show that by combining machine learning
+force fields (MLFFs) and DFT+U based molecular dynamics, it becomes possible to
+investigate the crystal structure of complex oxides as function of temperature
+and $U$. Here, we apply this method to the magnetic transition metal compounds
+LaMnO$_3$ and SrRuO$_3$. We show that the structural phase transition from
+orthorhombic to cubic in LaMnO$_3$, which is accompanied by the suppression of
+a Jahn-Teller distortion, can be simulated with an appropriate choice of $U$.
+For SrRuO$_3$, we show that the sequence of orthorhombic to tetragonal to cubic
+crystal phase transitions can be described with great accuracy. We propose that
+the $U$ values that correctly capture the temperature-dependent structures of
+these complex oxides, can be identified by comparison of the MLFF simulated and
+experimentally determined structures.",2312.06492v1
+2019-04-12,The magnetic structure factor of correlated moments in small-angle neutron scattering,"The interplay between structural and magnetic properties of nanostructured
+magnetic materials allows to realize unconventional magnetic effects, which
+results in a demand for experimental techniques to determine the magnetization
+profile with nanoscale resolution. Magnetic small-angle neutron scattering
+(SANS) probes both the chemical and magnetic nanostructure and is thus a
+powerful technique e.g. for the characterization of magnetic nanoparticles.
+Here, we show that the conventionally used particle-matrix approach to describe
+SANS of magnetic particle assemblies, however, leads to a flawed
+interpretation. As remedy, we provide general expressions for the
+field-dependent 2D magnetic SANS cross-section of correlated moments. It is
+shown that for structurally disordered ensembles the magnetic structure factor
+is in general, and contrary to common assumptions, (i) anisotropic also in zero
+field, and (ii) that even in saturation the magnetic structure factor deviates
+from the nuclear one. These theoretical predictions explain qualitatively the
+intriguing experimental, polarized SANS data of an ensemble of dipolar-coupled
+iron oxide nanoparticles.",1904.06243v3
+2023-09-24,FeCo Nanowire-Strontium Ferrite Powder Composites for Permanent Magnets with High-Energy Products,"Due to the issues associated with rare-earth elements, there arises a strong
+need for magnets with properties between those of ferrites and rare-earth
+magnets that could substitute the latter in selected applications. Here, we
+produce a high remanent magnetization composite bonded magnet by mixing FeCo
+nanowire powders with hexaferrite particles. In the first step, metallic
+nanowires with diameters between 30 and 100 nm and length of at least 2 {\mu}m
+are fabricated by electrodeposition. The oriented as-synthesized nanowires show
+remanence ratios above 0.76 and coercivities above 199 kA/m and resist core
+oxidation up to 300 {\deg}C due to the existence of a > 8 nm thin oxide
+passivating shell. In the second step, a composite powder is fabricated by
+mixing the nanowires with hexaferrite particles. After the optimal nanowire
+diameter and composite composition are selected, a bonded magnet is produced.
+The resulting magnet presents a 20% increase in remanence and an enhancement of
+the energy product of 48% with respect to a pure hexaferrite (strontium
+ferrite) magnet. These results put nanowire-ferrite composites at the forefront
+as candidate materials for alternative magnets for substitution of rare earths
+in applications that operate with moderate magnet performance.",2309.13724v1
+1996-06-12,Temperature and Pressure Effects on the Resistivity of the Manganese Oxides,"The temperature and pressure effects on the resistivity of the manganese
+oxides are studied analytically via the Kondo lattice model with a strong
+Hund's coupling. We obtain analytically the single-particle density of states
+on the Bethe lattice in the large connectivity limit using the analytical
+variant of the dynamic Lanczos method. From the density of states for the doped
+system, we obtain resistivity and show resistivity drop when temperature
+crosses the magnetic transition point. We also demonstrate the effect of
+pressure both below and above the transition temperature.",9606079v1
+1996-08-23,NMR in copper-Oxide Metals,"The anomalous part of the NMR relaxation rate of coppernuclei in the normal
+state of copper-oxide metals is calculated using the orbital magnetic parts of
+the fluctuations derived in a recent theory to explain the long wavelength
+transport anomalies. Oxygen and Yttrium reside on lattice sites at which the
+anomalous contribution is absent at all hole densities. The frequency, momentum
+dependence, and the form-factor of the fluctuations is predicted,which is
+verifiable by inelastic neutron scattering experiments.",9608109v1
+1997-10-22,X-Ray Resonant Scattering as a Direct Probe of Orbital Ordering in Transition-Metal Oxides,"X-ray resonant scattering at the K-edge of transition metal oxides is shown
+to measure the orbital order parameter, supposed to accompany magnetic ordering
+in some cases. Virtual transitions to the 3d-orbitals are quadrupolar in
+general. In cases with no inversion symmetry, such as V$_2$O$_3$, treated in
+detail here, a dipole component enhances the resonance. Hence, we argue that
+the detailed structure of orbital order in V$_2$O$_3$ is experimentally
+accessible.",9710232v1
+2001-03-21,Spin-Peierls transition with strong structural fluctuations in the vanadium oxide VOSb$_{2}$O$_{4}$,"We report on the magnetic susceptibility and electron spin resonance
+measurements on polycrystalline samples of the vanadium oxide
+VOSb$_{2}$O$_{4}$, a quasi-one dimensional S=1/2 Heisenberg system. We show
+that the susceptibility vanishes at zero temperature, as in a gapped system,
+and we argue that this is due to a spin-Peierls transition with strong
+structural fluctuations.",0103441v1
+2001-09-04,Structural Phase Transition in the Superconducting Pyrochlore Oxide Cd2Re2O7,"We report a structural phase transition found at Ts = 200 K in a pyrochlore
+oxide Cd2Re2O7 which shows superconductivity at Tc = 1.0 K. X-ray
+diffractionexperiments indicate that the phase transition is of the second
+order, from a high-temperature phase with the ideal cubic pyrochlore structure
+(space group Fd-3m) to a low-temperature phase with another cubic structure
+(space group F-43m). It is accompanied by a dramatic change in the resistivity
+and magnetic susceptibility and thus must induce a significant change in the
+electronic structure of Cd2Re2O7.",0109050v1
+2001-11-08,Superconducting properties of the pyrochlore oxide Cd2Re2O7,"We report the superconducting properties of the pyrochlore oxide Cd2Re2O7.
+The bulk superconducting transition temperature Tc is about 1.0 K, and the
+upper critical field Hc2 determined by the measurement of specific heat under
+magnetic fields is 0.29 T. The superconducting coherence length is estimated to
+be 34 nm. Specific heat data measured on single crystals suggest that the
+superconducting gap of Cd2Re2O7 is nodeless.",0111126v2
+2003-06-27,Kagomé in triangular lattice: electronic state of CoO_2 layer with hexagonal structure,"The electronic state in layered cobalt oxides with hexagonal structure is
+examined. We find that the electronic structure reflects the nature of the
+Kagom\'e lattice hidden in the CoO_2 layer which consists of stacked triangular
+lattices of oxygen ions and of cobalt ions. A fundamental model for the
+electron system is proposed and the mechanism of the unique transport and
+magnetic properties of the cobalt oxides are discussed in the light of the
+model.",0306696v1
+2004-03-24,New Pyrochlore Oxide Superconductor RbOs2O6,"We report the discovery of a new pyrochlore oxide superconductor RbOs2O6. The
+compound crystallizes in the same beta-pyrochlore structure as the recently
+discovered superconductor KOs2O6, where Os atoms form a corner-sharing
+tetrahedral network called the pyrochlore lattice with Rb or K atoms in the
+cage. Resistivity, magnetic susceptibility and specific heat measurements on
+polycrystalline samples evidence a bulk superconductivity with Tc = 6.3 K.",0403601v2
+2007-01-25,Spin-polarization coupling in multiferroic transition-metal oxides,"A systematic microscopic theory of magnetically induced ferroelectricity and
+lattice modulation is presented for all electron configurations of
+Mott-insulating transition-metal oxides. Various mechanisms of polarization are
+identified in terms of a strong-coupling perturbation theory. Especially, the
+spin-orbit interaction acting on the ligand p orbitals is shown to give the
+ferroelectric polarization of the spin-current form, which plays a crucial role
+particularly in eg systems. Semiquantitative agreements with the multiferroic
+TbMnO3 are obtained. Predictions for X-ray and neutron scattering experiments
+are proposed to clarify the microscopic mechanism of the spin-polarization
+coupling in different materials.",0701614v1
+2007-02-05,"Theory of Layered Iron Oxide on Frustrated Geometry: Electric Polarization, Magnetoelectric Effect and Orbital State","A layered iron oxide \rfeo ($R$: rare-earth elements) is an exotic dielectric
+material with charge-order (CO) driven electric polarization and
+magnetoelectric effect caused by spin-charge coupling. In this paper, a theory
+of electronic structure and dielectric property in \rfeo is presented. Charge
+frustration in paired-triangular lattices allows a charge imbalance without
+inversion symmetry. Spin frustration induces reinforcement of this polar CO by
+a magnetic ordering. We also analyze an orbital model for the Fe ion which does
+not show a conventional long-range order.",0702087v2
+2007-10-19,Paramagnonlike excitations and spin diffusion in magnetic resonance studies of copper oxide superconductors,"The relaxation function theory for a doped two-dimensional Heisenberg
+antiferromagnetic system in the paramagnetic state for all wave vectors through
+the Brillouin zone is presented in view of low frequency response of high-$T_c$
+copper oxide superconductors. We deduced the regions of long lifetime [$T
+\lesssim 400(1-4x)$ K] and ""overdamped"" [$T \gtrsim 700(1-4x)$ K]
+paramagnonlike excitations in the temperature ($T$)-doping index ($x$) phase
+diagram from plane oxygen nuclear spin-lattice relaxation rate $^{17}(1/T_1)$
+data in up to optimally doped La$_{2-x}$Sr$_{x}$CuO$_{4}$ thus providing the
+regimes for the spin wave concept and the ''overdamped'' mode.",0710.3615v1
+2007-10-25,The ground state phases of orbitally degenerate spinel oxides,"I review the microscopic spin-orbital Hamiltonian and ground state properties
+of spin one-half spinel oxides with threefold $t_{2g}$ orbital degeneracy. It
+is shown that for any orbital configuration a ground state of corresponding
+spin only Hamiltonian is infinitely degenerate in the classical limit. The
+extensive classical degeneracy is lifted by the quantum nature of the spins, an
+effect similar to order-out-of-disorder phenomenon by quantum fluctuations.
+This drives the system to a non-magnetic spin-singlet dimer manifold with a
+residual degeneracy due to relative orientation of dimers. The magneto-elastic
+mechanism of lifting the ``orientational'' degeneracy is also briefly reviewed.",0710.4773v1
+2008-11-04,Dual electronic states in thermoelectric cobalt oxide,"We investigate the low temperature magnetic field dependence of the
+resistivity in the thermoelectric misfit cobalt oxide [Bi1.7Ca2O4]0.59CoO2 from
+60 K down to 3 K. The scaling of the negative magnetoresistance demonstrates a
+spin dependent transport mechanism due to a strong Hund's coupling. The
+inferred microscopic description implies dual electronic states which explain
+the coexistence between localized and itinerant electrons both contributing to
+the thermopower. By shedding a new light on the electronic states which lead to
+a high thermopower, this result likely provides a new potential way to optimize
+the thermoelectric properties.",0811.0498v1
+2009-02-27,Modulation of superconductivity by spin canting in a hybrid antiferromagnet/superconductor oxide,"The proximity effect of a C-type antiferromagnet (C-AFM) with the spin
+canting at low temperature is investigated in the hybrid
+Nd0.35Sr0.65MnO3(NSCO)/YBa2Cu3O7(YBCO) oxide system through magnetic and
+transport measurements. It is found that the onset of a spin-canted state
+destroys partially the superconducting order parameter. Interestingly, due to
+the instability of this spin-canted state, zero-resistivity recovers at the
+offset of spin canting. Our result demonstrates clearly the high sensitivity of
+superconducting order parameter to a modulation of internal field.",0902.4737v1
+2011-02-18,Electron spin diffusion at the interface of multiferroic oxides,"We study the spin diffusion in a two-dimensional electron gas at the
+interface of oxide heterostructure LaAlO$_3$/SrTiO$_3$ grown on multiferroic
+TbMnO$_3$ at 15 K by means of the kinetic spin Bloch equation approach. The
+spiral magnetic moments of Mn$^{3+}$ in TbMnO$_3$ interact with the diffusing
+spins at the LaAlO$_3$/SrTiO$_3$ interface via the Heisenberg exchange
+interaction. It is demonstrated that the spin diffusion length is always
+finite, despite the polarization direction of the injected spins. Our study
+also reveals the important role played by the Coulomb scattering, which can
+effectively suppress the spin diffusion.",1102.3757v1
+2011-09-06,Topological insulators from complex orbital order in transition-metal oxides heterostructures,"Topological band insulators which are dynamically generated by
+electron-electron interactions have been the- oretically proposed in two and
+three dimensional lattice models. We present evidence that the two-dimensional
+version can be stabilized in digital (111) heterostructures of transition-metal
+oxides as a result of purely local interactions. The topological phases are
+accompanied by spontaneous ordering of complex orbitals and we discuss their
+stability with respect to the Hund's rule coupling, Jahn-Teller interaction and
+inversion symmetry breaking terms. As main competitors we identify spin-nematic
+and magnetic phases.",1109.1297v2
+2015-03-25,All-oxide spin Seebeck effects,"We report the observation of longitudinal spin Seebeck effects (LSSE) in an
+all-oxide bilayer system comprising an IrO$_2$ film and an Y$_3$Fe$_5$O$_{12}$
+film. Spin currents generated by a temperature gradient across the
+IrO$_2$/Y$_3$Fe$_5$O$_{12}$ interface were detected as electric voltage via the
+inverse spin Hall effect in the conductive IrO$_2$ layer. This electric voltage
+is proportional to the magnitude of the temperature gradient and its magnetic
+field dependence is well consistent with the characteristic of the LSSE. This
+demonstration may lead to the realization of low-cost, stable, and transparent
+spin-current-driven thermoelectric devices.",1503.07378v1
+2017-03-04,"Specific Cation Diffusion across the (La,Sr)MnO3 (Ce,Gd)O2 interface in SOFCs","Oxide interfaces play very important roles for the physical and chemical
+properties of nanostructured materials, such as an ionic conductivity,
+superconductivity, and magnetism. Gadolinia-doped Ceria (GDC) is commonly
+selected as the interlayer between (La,Sr)MnO3 and Y2O3-stabilized ZrO2 in fuel
+cells. The chemical expansions across the oxide interlayer were carefully
+examined at the atomic resolution in order to understand the cation diffusion
+and existence of oxygen deficiency at the interfaces.",1703.01373v1
+2016-08-09,Search for the magnetocaloric effect in multiferroics oxides,"In this paper, we report on the magnetocaloric properties of some selected
+multiferroic oxides, namely HoMn2O5 and La2(Ni,Co)MnO6 compounds which exhibit
+transition points from 10K up to almost room temperature. In order to avoid
+grain boundary effects and structural inhomogeneity observed frequently in
+polycrystalline samples, only single crystals were considered for this study.",1608.02809v1
+2016-12-16,Relaxation mechanism driven by spin angular momentum absorption throughout antiferromagnetic phase transition in NiFe surface oxides,"We report an alternative mechanism for the physical origin of the
+temperature-dependent ferromagnetic relaxation of Permalloy (NiFe) thin films.
+Through spin-pumping experiments, we demonstrate that the peak in the
+temperature-dependence of NiFe damping can be understood in terms of enhanced
+spin angular momentum absorption at the magnetic phase transition in
+antiferromagnetic surface-oxidized layers. These results suggest new avenues
+for the investigation of an incompletely-understood phenomenon in physics.",1612.05556v1
+2017-11-08,Micromagnetic simulation study of a disordered model for one-dimensional granular perovskite manganite oxide nanostructures,"Chemical techniques are an efficient method to synthesize one-dimensional
+perovskite manganite oxide nanostructures with a granular morphology, that is,
+formed by arrays of monodomain magnetic nanoparticles. Integrating the
+stochastic Landau-Lifshitz-Gilbert equation, we simulate the dynamics of a
+simple disordered model for such materials that only takes into account the
+morphological characteristics of their nanograins. We show that it is possible
+to describe reasonably well experimental hysteresis loops reported in the
+literature for single La_0.67Ca_0.33MnO_3 nanotubes and powders of these
+nanostructures, simulating small systems consisting of only 100 nanoparticles.",1711.03159v2
+2017-11-21,Current-induced spin polarization in isotropic k-cubed Rashba model: Theoretical study for p-doped semiconductor heterostructures and perovskite oxides interfaces,"Using the Matsubara Green's function formalism we calculate the temperature
+dependence of the nonequilibrium spin polarization induced by an external
+electric field in the presence of spin-orbit coupling. The model Hamiltonian
+includes an isotropic k-cubed form of the Rashba spin-orbit interaction. Such a
+Hamiltonian captures the electronic and spin properties of two-dimensional
+electron (hole) gas at the surfaces or interfaces of transition metal oxides or
+in p-doped semiconductor heterostructures. The induced spin polarization is
+calculated for the nonmagnetic as well as magnetic electron/hole gas. Relation
+of the spin polarization to the Berry curvature is also discussed.",1711.07707v1
+2020-10-09,Tunable Magnetism and Insulator-Metal Transition in Bilayer Perovskites,"Two-dimensional (2D) transition-metal oxide perovskites greatly expand the
+field of available 2D multifunctional material systems. Here, based on density
+functional theory calculations, we predicted the presence of ferromagnetism
+orders accompanying with an insulator-metal phase transition in bilayer
+$KNbO_{3}$ and $KTaO_{3}$ by applying strain engineering and/or external
+electric field. Our results will contribute to the applications of few-layer
+transition metal oxide perovskites in the emerging spintronics and
+straintronics.",2010.04766v1
+2018-02-12,Canted ferrimagnetism and giant coercivity in the non-stoichiometric double perovskite La2Ni1.19Os0.81O6,"The non-stoichiometric double perovskite oxide La2Ni1.19Os0.81O6 was
+synthesized by solid state reaction and its crystal and magnetic structures
+were investigated by powder x-ray and neutron diffraction. La2Ni1.19Os0.81O6
+crystallizes in the monoclinic double perovskite structure (general formula
+A2BB'O6) with space group P21/n, where the B site is fully occupied by Ni and
+the B' site by 19 % Ni and 81 % Os atoms. Using x-ray absorption spectroscopy
+an Os4.5+ oxidation state was established, suggesting presence of about 50 %
+paramagnetic Os5+ (5d3, S = 3/2) and 50 % non-magnetic Os4+ (5d4, Jeff = 0)
+ions at the B' sites. Magnetization and neutron diffraction measurements on
+La2Ni1.19Os0.81O6 provide evidence for a ferrimagnetic transition at 125 K. The
+analysis of the neutron data suggests a canted ferrimagnetic spin structure
+with collinear Ni2+ spin chains extending along the c axis but a non-collinear
+spin alignment within the ab plane. The magnetization curve of
+La2Ni1.19Os0.81O6 features a hysteresis with a very high coercive field, HC =
+41 kOe, at T = 5 K, which is explained in terms of large magnetocrystalline
+anisotropy due to the presence of Os ions together with atomic disorder. Our
+results are encouraging to search for rare earth free hard magnets in the class
+of double perovskite oxides.",1802.03874v1
+2019-03-04,Structural and magnetic properties in sputtered iron oxide epitaxial thin films -- Magnetite Fe$_3$O$_4$ and epsilon ferrite e-Fe$_2$O$_3$,"Epitaxial thin film fabrication of iron oxides including magnetite Fe3O4 and
+epsilon-ferrite epsilon-Fe2O3 with the potential for advancing electromagnetic
+devices has been investigated, which led to the first ever epsilon-ferrite
+epitaxial layer being synthesized in the conventional sputtering process.
+Concerning Fe3O4 (100) / MgO (100) films, a cube-on-cube epitaxial relationship
+and sharp rocking curves with FWHM of 50 - 350 arcsec were confirmed regardless
+of the small amount of Ge additions. Sputtering Ar gas pressure PAr heavily
+influenced their magnetic and transport properties. High PAr = 15 mTorr caused
+a high magnetization of 6.52 kG for the Ge added sample and the clear Verwey
+transition at 122 K for the non Ge addition case. Conversion electron Mossbauer
+spectroscopy (CEMS) measurements revealed that low PAr < 10 mTorr causes Fe/O
+off-stoichiometry on the oxidizing side for the non Ge addition case and the
+reductive side for the Ge addition case, respectively. Regarding the
+epsilon-Fe2O3 (001) / SrTiO3(111) epilayer synthesis, bilayer microstructure
+composed of an approximately 5nm thick initially grown epsilon-Fe2O3 (001)
+epilayer and subsequently grown e-Fe2O3 (001) epilayer was confirmed from
+cross-sectional TEM observations. The coexistence of magnetically hard and soft
+phases was confirmed from the magnetization measurements. As a possible
+application of the single nm thick epsilon-Fe2O3 layer, 4-resistive-state
+multiferroic tunnel junction (MFTJ) is considered.",1903.01022v1
+2019-03-12,Zero Field Assembly of Long Magnetic Dipolar Chains in 2D Polymer Nanocomposite Films,"The existence of magnetic dipolar nanoparticle chains at zero field has been
+predicted theoretically for decades, but these structures are rarely observed
+experimentally. A prerequisite is a permanent magnetic moment on the particles
+forming the chain. Here we report on the observation of magnetic dipolar chains
+of spherical iron oxide nanoparticles with a diameter of
+\SI{12.8}{\nano\meter}. The nanoparticles are embedded in an ultrathin polymer
+film. Due to the high viscosity of the polymer matrix, the dominating
+aggregation mechanism is driven by dipolar interactions. Smaller iron oxide
+nanoparticles (\SI{9.4}{\nano\meter}) show no permanent magnetic moment and do
+not form chains but compact aggregates. Mixed monolayers of different iron
+oxide nanoparticles and polymer at the air-water interface are characterized by
+Langmuir isotherms and in-situ X-ray reflectometry (XRR). The combination of
+the particles with a polymer leads to a stable polymer nanocomposite film at
+the air-water interface. XRR experiments show that nanoparticles are immersed
+in a thin polymer matrix of \SI{3}{\nano\meter}. Using atomic force microscopy
+(AFM) on Langmuir-Blodgett films, we measure the lateral distribution of
+particles in the film. An analysis of single structures within transferred
+films results in fractal dimensions that are in excellent agreement with 2D
+simulations.",1903.04877v1
+2021-06-07,High-mobility two-dimensional carriers from surface Fermi arcs in magnetic Weyl semimetal films,"High-mobility two-dimensional carriers originating from surface Fermi arcs in
+magnetic Weyl semimetals are highly desired for accessing exotic quantum
+transport phenomena and for topological electronics applications. Here, we
+demonstrate high-mobility two-dimensional carriers that show quantum
+oscillations in magnetic Weyl semimetal SrRuO3 epitaxial films by systematic
+angle-dependent, high-magnetic field magnetotransport experiments. The
+exceptionally high-quality SrRuO3 films were grown by state-of-the-art oxide
+thin film growth technologies driven by machine learning algorithm. The quantum
+oscillations for the 10-nm SrRuO3 film show a high quantum mobility of 3500
+cm2/Vs, a light cyclotron mass, and two-dimensional angular dependence, which
+can be attributed to the surface Fermi arcs. The linear thickness dependence of
+the phase shift of the quantum oscillations provides evidence for the
+non-trivial nature of the quantum oscillations mediated by the surface Fermi
+arcs. In addition, at low temperatures and under magnetic fields of up to 52 T,
+the quantum limit of SrRuO3 manifests the chiral anomaly of the Weyl nodes.
+Emergence of the hitherto hidden two-dimensional Weyl states in a ferromagnetic
+oxide pave the way to explore novel quantum transport phenomena for topological
+oxide electronics.",2106.03292v2
+2021-10-24,$^{139}$La-NMR study of spin-dynamics coupled with hole mobility in $T$*-type La$_{0.86}$Eu$_{0.86}$Sr$_{0.28}$CuO$_{4-δ}$,"In $T$*-type cuprate oxides with five oxygen coordination, little is known
+about the relationship between the spin correlations and dope carriers. We
+performed $^{139}$La-nuclear magnetic resonance (NMR) and electrical
+resistivity measurements on an as-sintered (AS) and oxidation annealed (OA)
+polycrystalline $T$*-type La$_{0.86}$Eu$_{0.86}$S$_{0.28}$CuO$_4$ (LESCO) to
+investigate its magnetic and superconducting (SC) properties. Upon cooling, the
+NMR spectrum of AS LESCO broadened below 3 K, at which the nuclear spin-lattice
+relaxation rate $1/T_1$ against the temperature exhibited a maximum, thereby
+indicating the appearance of static magnetism. The temperature dependence of
+$1/T_1$ between 3 K and 20 K was similar to that of the resistivity displaying
+the semiconducting behavior. Furthermore, the energy scale of the transport gap
+and spin-dynamics estimated was found to be comparable. These results suggest a
+close connection between the mobility of the doped carriers and low-energy
+spin-dynamics, as reported for lightly doped $T$-type La$_{2-x}$Sr$_x$CuO$_4$.
+In the OA SC sample, we confirmed the absence of a magnetic order and the
+Korringa relation above 10 K. Therefore, in the $T$*-type LESCO with $x$ =
+0.28, the magnetic state coupled with holes drastically turns to the weakly
+correlated metallic state by oxidation annealing.",2110.12333v1
+2022-12-21,"Large anomalous Hall, Nernst effect and topological phases in the 3d-4d/5d based oxide double perovskites","Magnetic topological quantum materials are attracting considerable attention
+owing to their potential technological applications. However, only a small
+number of these materials have been experimentally realized, thereby giving
+rise to the need for new stable magnetic topological quantum materials.
+Magnetism and spin-orbit coupling, two essential ingredients of the oxide
+materials, lead to various topological transport phenomena such as the
+anomalous Hall and anomalous Nernst effects, which can be significantly
+enhanced by designing an electronic structure with a large Berry curvature. In
+that respect, double perovskites with the general formula A$_2$BB'O$_6$ with an
+alternating ordered arrangement of two transition metal sites, B(3d) and
+B'(4d/5d), present attractive possibilities as they are robustly stable against
+oxidation under ambient conditions and versatile. These double perovskites also
+offer a high energy scale for magnetism as well as strong spin-orbit coupling
+with a high magnetic ordering temperature. Here, using first-principles density
+functional theory calculations, we present a comprehensive study of the
+intrinsic anomalous transport for 3d-4d/5d based cubic and tetragonal stable
+double perovskite (DP) compounds. A few of the DPs exhibit a very large
+anomalous Hall effect with a distinct topological band crossing in the vicinity
+of the Fermi energy. Our results show the importance of symmetries,
+particularly the mirror planes, as well as the clean topological band crossing
+near the Fermi energy, which is primarily contributed by the 5d-t$_{2g}$ for
+large anomalous Hall and Nernst effects.",2212.11324v1
+1997-08-29,Electronic States and Magnetic Propertis of Edge-sharing Cu-O Chains,"The electronic states and magnetic properties for the copper oxides
+containing edge-sharing Cu-O chains such as Li$_2$CuO$_2$,
+La$_6$Ca$_8$Cu$_{24}$O$_{41}$ and CuGeO$_3$ are systematically studied. The
+optical conductivity $\sigma(\omega)$ and the temperature dependence of the
+magnetic susceptibility $\chi(T)$ for single crystalline samples Li$_2$CuO$_2$
+are measured as a reference system and analyzed by using the exact
+diagonalization method for small Cu-O clusters. It is shown that the spectral
+distribution of $\sigma(\omega)$ is different between edge-sharing and
+corner-sharing Cu-O-Cu bonds. The charge transfer gap in edge-sharing chains is
+larger than that of high-$T_{c}$ cuprates. The exchange interaction between
+nearest-neighbor copper ions in edge-sharing chains $J_1$ depends sensitively
+on the Cu-O-Cu bond angles. In addition to $J_1$, the exchange interaction
+between next-nearest-neighbor copper ions $J_2$ has sufficient contribution to
+the magnetic properties. We calculate $J_1$ and $J_2$ for all the copper oxides
+containing edge-sharing Cu-O chains and discuss the magnetic properties.",9708232v2
+2003-06-17,"Magnetic behaviour of quasi-one-dimensional oxides, Ca$_3$Co$_(1+x)$Mn$_{1-x}$O$_6$","The results of ac and dc magnetization and heat capacity measurements on the
+oxides, Ca$_3$Co$_{1+x}$Mn$_{1-x}$O$_6$, forming in a K$_4$CdCl$_6$-derived
+rhombohedral quasi-one-dimensional crystal structure, are reported. As far as
+Ca$_3$Co$_2$O$_6$ is concerned, the results reveal truly complex nature of the
+two magnetic transitions, identified to set in at 24 and 12 K in the previous
+literature. However, partial replacement of Co by Mn apparently results in a
+long magnetic ordering of an antiferromagnetic type (below 13 and 18 K for x=
+0.0 and 0.25 respectively), instead of spin-glass freezing in spite of the fact
+that there is Co-Mn disorder; in addition, interestingly there are hysteretic
+spin reorientation effects as revealed by isothermal magnetization behavior.",0306426v1
+2005-10-14,Crossover between local-moment magnetism and itinerant-electron magnetism in the t-J model,"A Kondo-lattice theory is applied to the crossover between local-moment
+magnetism for almost half fillings of electrons and itinerant-electron
+magnetism away from the half filling. In clean systems with no disorder, the
+bandwidth W^* of quasiparticles is non-zero and of the order of |J| at T=0K
+even in the limit of the half filling, with J the superexchange interaction
+constant between nearest neighbors. The so called Gutzwiller's term also
+contributes to W^* away from the half filling; it is approximately proportional
+to doping concentrations measured from the half filling. Magnetism is enhanced
+by disorder because the renormalization of W^* by J is reduced by disorder. The
+asymmetry of disorder between electron-doped and hole-doped cuprate oxide
+superconductors must be, at least partly, responsible for that of
+antiferromagnetic phases between them. The so called Kumagai phase is
+characterized as an SDW state in a disordered system rather than a spin glass.
+The Neel temperature T_N about 300K of non-doped cuprate oxides can be
+explained by the reduction of T_N by critical thermal antiferromagnetic
+fluctuations in quasi-two dimensions.",0510377v1
+2009-03-16,Spin Ice,"Geometric frustration usually arises in systems that comprise magnetic
+moments (spins) which reside on the sites of a lattice made up of elementary
+triangular or tetrahedral units and which interact via antiferromagnetic
+nearest-neighbor exchange. Albeit much less common, geometric frustration can
+also arise in systems with strong non-collinear single-ion easy-axis
+(Ising-like) anisotropy and ferromagnetically} coupled spins. This is what
+happens in some pyrochlore oxide materials where Ising-like magnetic rare earth
+moments (Ho$^{3+}$, Dy$^{3+}$) sit on a lattice of corner-shared tetrahedra and
+are coupled via effectively ferromagnetic (dipolar) interactions. These systems
+possess a macroscopic number of quasi-degenerate classical ground states and
+display an extensive low-temperature entropy closely related to the extensive
+proton disorder entropy in common water ice. For this reason, these magnetic
+systems are called {\it spin ice}. This chapter reviews the essential
+ingredients of spin ice phenomenology in magnetic pyrochlore oxides.",0903.2772v1
+2010-07-22,Strong reduction of V4+ amount in vanadium oxide/hexadecylamine nanotubes by doping with Co2+ and Ni2+ ions: EPR and magnetic studies,"In this work we present a complete characterization and magnetic study of
+vanadium oxide/hexadecylamine nanotubes (VOx/Hexa NT's) doped with Co2+ and
+Ni2+ ions. The morphology of the NT's has been characterized by Transmission
+Electron Microscopy (TEM) while the metallic elements have been quantified by
+Instrumental Neutron Activation Analysis (INAA) technique. The static and
+dynamic magnetic properties were studied collecting data of magnetization as a
+function of magnetic field and temperature and by Electron Paramagnetic
+Resonance (EPR). We observed that the incorporation of metallic ions (Co2+,
+S=3/2 and Ni2+, S=1) decrease notably the amount of V4+ ions in the system,
+from 14-16% (non-doped case) to 2-4%, with respect to the total vanadium atoms
+into the tubular nanostructure, improving considerably their potential
+technological applications as Li-ion batteries cathodes.",1007.3968v1
+2011-04-08,Magnetic nanocomposites at microwave frequencies,"Most conventional magnetic materials used in the electronic devices are
+ferrites, which are composed of micrometer-size grains. But ferrites have small
+saturation magnetization, therefore the performance at GHz frequencies is
+rather poor. That is why functionalized nanocomposites comprising magnetic
+nanoparticles (e.g. Fe, Co) with dimensions ranging from a few nm to 100 nm,
+and embedded in dielectric matrices (e.g. silicon oxide, aluminium oxide) have
+a significant potential for the electronics industry. When the size of the
+nanoparticles is smaller than the critical size for multidomain formation,
+these nanocomposites can be regarded as an ensemble of particles in
+single-domain states and the losses (due for example to eddy currents) are
+expected to be relatively small. Here we review the theory of magnetism in such
+materials, and we present a novel measurement method used for the
+characterization of the electromagnetic properties of composites with
+nanomagnetic insertions. We also present a few experimental results obtained on
+composites consisting of iron nanoparticles in a dielectric matrix.",1104.1535v1
+2011-05-09,Unconventional Magnetism in a Nitrogen-Based Analogue of Cupric Oxide,"We have investigated the magnetic properties of CuNCN, the first
+nitrogen-based analogue of cupric oxide, CuO. Our muon spin relaxation, nuclear
+magnetic resonance and electron spin resonance studies reveal that classical
+magnetic ordering is absent down to lowest temperatures. However, large
+enhancement of spin correlations and unexpected inhomogeneous magnetism have
+been observed below 80 K. We attribute this to a peculiar fragility of the
+electronic state against weak perturbations due to geometrical frustration,
+which selects between competing spin-liquid and more conventional frozen
+states.",1105.1691v2
+2012-12-26,Epitaxial strain induced magnetic transitions and phonon instabilities of the tetragonal SrRuO3,"Using density-functional theory calculations, we investigate the magnetic as
+well as the dynamical properties of tetragonal SrRuO3 (SRO) under the influence
+of epitaxial strain. It is found that both the tensile and compressive strain
+in the xy-plane could induce the abrupt change in the magnetic moment of Ru
+atom. In particular, under the in-plane ~4% compressive strain, a ferromagnetic
+to nonmagnetic transition is induced. Whereas for the tensile strain larger
+than 3%, the Ru magnetic moment drops gradually with the increase of the
+strain, exhibiting a weak ferromagnetic state. We find that such magnetic
+transitions could be qualitatively explained by the Stoner model. In addition,
+frozen phonon calculations at {\Gamma} point reveal structural instabilities
+could occur under both compressive and tensile strains. Such instabilities are
+very similar to those of the ferroelectric perovskite oxides, even though SRO
+remains to be metallic in the range we studied. These might have influence on
+the physical properties of oxide supercells taking SRO as constituent.",1212.6132v1
+2014-01-06,Engineering spin-orbital magnetic insulator by tailoring superlattices,"Novel interplay of spin-orbit coupling and electron correlations in complex
+Ir oxides recently emerged as a new paradigm for correlated electron physics.
+Because of a large spin-orbit coupling of ~0.5 eV, which is comparable to the
+transfer energy t and the crystal field splitting $\Delta$ and Coulomb U, a
+variety of ground states including magnetic insulator, band insulator,
+semimetal and metal, shows up in a narrow materials phase space. Utilizing such
+subtle competition of the ground states, we successfully tailor a spin-orbital
+magnetic insulator out of a semimetal SrIrO$_3$ by controlling dimensionality
+using superlattice of [(SrIrO$_3$)$_m$, SrTiO$_3$] and show that a magnetic
+ordering triggers the transition to magnetic insulator. Those results can be
+described well by a first-principles calculation. This study is an important
+step towards the design and the realization of topological phases in complex Ir
+oxides with very strong spin-orbit coupling.",1401.1066v1
+2015-02-01,Lifshitz metal-insulator transition induced by the all-in/all-out magnetic order in the pyrochlore oxide Cd2Os2O7,"We investigate the metal-insulator transition (MIT) of the osmium pyrochlore
+oxide Cd2Os2O7 through transport and magnetization measurements. The MIT and a
+magnetic transition to the all-in/all-out (AIAO) order occur simultaneously at
+227 K. We propose a mechanism based on a Lifshitz transition induced by the
+AIAO magnetic order probably via strong spin-orbit couplings in the specific
+semimetallic band structure. It is suggested, moreover, that two observed
+puzzles, a finite conductivity near T = 0 and an emergence of weak
+ferromagnetic moments, are not bulk properties but originate at magnetic domain
+walls between two kinds of AIAO domains.",1502.00191v1
+2015-11-30,Spin-orbit driven magnetic insulating state with ${J}_{\mathrm{eff}}\mathbf{=}1/2$ character in a 4d oxide,"The unusual magnetic and electronic ground states of 5d iridates has been
+shown to be driven by intrinsically enhanced spin-orbit coupling (SOC). The
+influence of appreciable but reduced SOC in creating the manifested magnetic
+insulating states in 4d oxides is less clear, with one hurdle being the
+existence of such compounds. Here we present experimental and theoretical
+results on Sr$_4$RhO$_6$ that reveal SOC dominated behavior. Neutron
+measurements show the octahedra are both spatially separated and locally ideal,
+making the electronic ground state susceptible to alterations by SOC. Magnetic
+ordering is observed with a similar structure to an analogous
+${J}_{\mathrm{eff}}\mathbf{=}1/2$ Mott iridate. We consider the underlying role
+of SOC in this rhodate with density functional theory and x-ray absorption
+spectroscopy and find a magnetic insulating ground state with
+${J}_{\mathrm{eff}}\mathbf{=}1/2$ character.",1511.09431v1
+2018-02-26,Evolution of ferromagnetism in two-dimensional electron gas of LaTiO3/SrTiO3,"Understanding, creating, and manipulating spin polarization of
+two-dimensional electron gases at complex oxide interfaces presents an
+experimental challenge. For example, despite almost a decade long research
+effort, the microscopic origin of ferromagnetism in LaAlO3/SrTiO3
+heterojunction is still an open question. Here, by using a prototypical
+two-dimensional electron gas (2DEG) which emerges at the interface between band
+insulator SrTiO3 and antiferromagnetic Mott insulator LaTiO3 , the experiment
+reveals the evidence for magnetic phase separation in hole-doped Ti d1 t2g
+system resulting in spin-polarized 2DEG. The details of electronic and magnetic
+properties of the 2DEG were investigated by temperature-dependent d.c.
+transport, angle-dependent X-ray photoemission spectroscopy, and
+temperature-dependent magnetoresistance. The observation of clear hysteresis in
+magnetotransport at low magnetic fields implies spin-polarization from magnetic
+islands in the hole rich LaTiO3 near the interface. These findings emphasize
+the role of magnetic instabilities in doped Mott insulators thus providing
+another path for designing all-oxide structures relevant to spintronics
+applications.",1802.09614v1
+2014-03-16,Theory of the Magnetic Resonance for the High-$T_C$ Copper-Oxide Superconductors,"The magnetic response expected from a state characterized by rotating
+antiferromagnetism in a neutron-scattering experiment is calculated. We predict
+the occurrence of a peak at the frequency of the rotation of the rotating
+antiferromagnetic order parameter. The doping dependence of this frequency is
+very similar to that of the frequency of the magnetic resonance observed in the
+neutron-scattering experiments for the hole-doped high-$T_C$ cuprates. This
+leads us to propose the rotating antiferromagnetism as a possible mechanism for
+this magnetic resonance. We conclude that while the magnitude of the rotating
+antiferromagnetic order parameter was previously proposed to be responsible for
+the pseudogap and the unusual thermodynamic and transport properties, the phase
+of the rotating order parameter is proposed here to be responsible for the
+unusual magnetic properties of the high-$T_C$ copper-oxide superconductors.",1403.3968v2
+2016-08-10,Exchange bias in a mixed metal oxide based magnetocaloric compound YFe0.5Cr0.5O3,"We report a detailed investigation of magnetization, magnetocaloric effect
+and exchange bias studies on a mixed metal oxide YFe0.5Cr0.5O3 belonging to
+perovskite family. Our results reveal that the compound is in canted magnetic
+state (CMS) where ferromagnetic correlations are present in an
+antiferromagnetic state. Magnetic entropy change of this compound follows a
+power law (deltaS_M ~ H^m) dependence of magnetic field. In this compound,
+inverse magnetocaloric effect (IMCE) is observed below 260 K while conventional
+magnetocaloric effect (CMCE) above it. The exponent m is found to be
+independent of temperature and field only in the IMCE region. Investigation of
+temperature and magnetic field dependence studies of exchange bias, reveal a
+competition between effective Zeeman energy of the ferromagnetic regions and
+anisotropic exchange energy at the interface between ferromagnetic and
+antiferromagnetic regions. Variation of exchange bias due to temperature and
+field cycling is also investigated.",1608.03223v1
+2017-06-08,Characterization of physicochemical and colloidal properties of hydrogel chitosan-coated iron-oxide nanoparticles for cancer therapy,"Superparamagnetic iron oxide nanoparticles have recently been investigated
+for their potential to kill cancer cells with promising results, owing to their
+ability to be targeted and heated by magnetic fields. In this study, novel
+hydrogel, chitosan Fe3O4 magnetic nanoparticles were synthesized to induce
+magnetic hyperthermia, and targeted delivering of chemotherapeutics in the
+cancer microenvironment. The characteristic properties of synthesized bare and
+CS-MNPs were analyzed by various analytical methods: X-ray diffraction, Fourier
+transformed infrared spectroscopy, Scanning electron microscopy and
+Thermo-gravimetric analysis/differential thermal analysis. Magnetic
+nanoparticles were successfully synthesized using the co-precipitation method.
+This synthesis technique resulted in nanoparticles with an average particle
+size of 16 nm. The pure obtained nanoparticles were then successfully
+encapsulated with 4-nm-thick chitosan coating. The formation of chitosan on the
+surface of nanoparticles was confirmed by physicochemical analyses. Heating
+experiments at safe magnetic field (f = 100 kHz, H =10-20 kA m-1) revealed that
+the maximum achieved temperature of water stable chitosan-coated nanoparticles
+(50 mg ml-1) is fully in agreement with cancer therapy and biomedical
+applications.",1706.02590v1
+2017-06-20,Hidden peculiar magnetic anisotropy at the interface in a ferromagnetic perovskite-oxide heterostructure,"Understanding and controlling the interfacial magnetic properties of
+ferromagnetic thin films are crucial for spintronic device applications.
+However, using conventional magnetometry, it is difficult to detect them
+separately from the bulk properties. Here, by utilizing tunneling anisotropic
+magnetoresistance in a single-barrier heterostructure composed of
+La0.6Sr0.4MnO3 (LSMO)/ LaAlO3 (LAO)/ Nb-doped SrTiO3 (001), we reveal the
+presence of a peculiar strong two-fold magnetic anisotropy (MA) along the
+[110]c direction at the LSMO/LAO interface, which is not observed in bulk LSMO.
+This MA shows unknown behavior that the easy magnetization axis rotates by
+90{\deg} at an energy of 0.2 eV below the Fermi level in LSMO. We attribute
+this phenomenon to the transition between the eg and t2g bands at the LSMO
+interface. Our finding and approach to understanding the energy dependence of
+the MA demonstrate a new possibility of efficient control of the interfacial
+magnetic properties by controlling the band structures of oxide
+heterostructures.",1706.06300v1
+2017-07-15,Structural and magnetic properties of lightly doped M-type hexaferrites,"Vanadium substituted SrM hexaferrites (SrFe12-xVxO19 with x = 0.2, 0.4) and
+Eu-substituted BaM hexaferrite (Ba0.8Eu0.2Fe12O19) were prepared by high energy
+ball milling and sintering at 1200{\deg} C. X-ray diffraction measurements
+revealed that the V-substituted SrM samples exhibited phase separation
+resulting in the coexistence of the pure SrM magnetic phase with nonmagnetic
+Sr3(VO4)2 vanadate and {\alpha}-Fe2O3 iron oxide phase. Also, the
+Eu-substituted BaM hexaferrite revealed the formation of the pure BaM phase
+coexisting with {\alpha}-Fe2O3 secondary phase, and Eu-garnet minor phase.
+Although the magnetic properties of the samples deteriorated with respect to
+pure hexaferrite properties, the magnetic parameters of the substituted samples
+were found to be of potential importance for practical applications. Further,
+the results of the study suggest methods for the preparation of high quality
+SrM hexaferrites, and hexaferrite/garnet composites.",1707.04709v1
+2018-01-16,3D Crystallographic Alignment of Alumina Ceramics by Application of Low Magnetic Fields,"Non-cubic crystals exhibit anisotropic physical and functional properties.
+Microscopic crystallites as constituents of polycrystalline materials are
+randomly oriented, thus polycrystalline ceramics lack the anisotropic
+properties of their monocrystalline counterparts. We propose a technology that
+exploits the synergy between magnetic alignment and colloidal ceramics
+processing, and enables to independently tune the orientation of grains in
+different sample regions by infinitesimal magnetic fields (<10 millitesla). The
+grain pivot mechanism enables the emulation of single crystals, as well as the
+creation of large complex-shaped ceramic elements with designed
+crystallographic landscapes and spatially and directionally tuned properties.
+Ultra-high magnetic response arises from magnetic shape anisotropy of
+platelet-shaped seed crystallites coated with small amounts of iron oxide
+nanoparticles. To control crystallographic growth directions during subsequent
+annealing procedures, the seeds are dispersed and aligned in a matrix of
+chemically identical, but much finer spherical particles. The degree of
+crystalline orientation in accordingly prepared aluminum oxide exceeds 99%.
+This technology opens an avenue to remarkably improve structural and functional
+properties of ceramic elements employed in numerous industrial applications.",1801.05102v3
+2020-12-18,Frustrated Magnetism in Fluoride and Chalcogenide Pyrochlore Lattice Materials,"Pyrochlore lattices, which are found in two important classes of materials --
+the $A_2B_2X_7$ pyrochlore family and the $AB_2X_4$ spinel family -- are the
+quintessential 3-dimensional frustrated lattice architecture. While
+historically oxides ($X =$~O) have played the starring role in this field, the
+past decade has seen materials synthesis breakthroughs that have lead to the
+emergence of fluoride ($X =$~F) and chalcogenide ($X =$~S, Se) pyrochlore
+lattice materials. In this Research Update, we summarize recent progress in
+understanding the magnetically frustrated ground states in three families of
+non-oxide pyrochlore lattice materials: (i) $3d$-transition metal fluoride
+pyrochlores, (ii) rare earth chalcogenide spinels, and (iii) chromium
+chalcogenide spinels with a breathing pyrochlore lattice. We highlight how the
+change of anion can modify the single ion spin anisotropy due to crystal
+electric field effects, stabilize the incorporation of new magnetic elements,
+and dramatically alter the exchange pathways and thereby lead to new magnetic
+ground states. We also consider a range of future directions -- materials with
+the potential to define the next decade of research in frustrated magnetism.",2012.10060v2
+2021-03-11,Stimuli-responsive assembly of iron oxide nanoparticles into magnetic flexible filaments,"The combination of multiple functionalities in a single material is an
+appealing strategy for the de-velopment of smart materials with unique
+features. In this work, we present the preparation of thermoresponsive magnetic
+nanoparticles and their one-dimensional assembly into transient
+micro-filaments. The material is based on 9.4 nm iron oxide nanoparticles
+grafted with poly(N-n-propylacrylamide) via multiphosphonic acid anchoring
+sites. The hybrid nanoparticles present a low critical solution temperature
+(LCST) transition between 21 {\deg}C and 28 {\deg}C, depending on the pH and
+the ionic strength. When heated above the LCST in defined conditions, the
+nanoparticles ag-gregate and respond to an external magnetic field. An
+intrinsic characteristic of the thermorespon-sive particles is an asymmetric
+transition between cooling and heating cycles, that was favorably exploited to
+build one-dimensional permanent microstructures, such as magnetic
+microfilaments and cilia. In summary, we present the development of a
+nanoplatform responsive to multiple stimu-li, including temperature, magnetic
+field, pH and ionic strength and its transformation into magneti-cally active
+microfilaments that could find potential applications in remotely controlled
+devices.",2103.06837v1
+2021-07-16,Defect engineering of magnetic ground state in EuTiO$_3$ epitaxial thin films,"Atomistic defect engineering through the pulsed laser epitaxy of perovskite
+transition metal oxides offers facile control of their emergent
+opto-electromagnetic and energy properties. Among the various perovskite
+oxides, EuTiO3 exhibits a strong coupling between the lattice, electronic, and
+magnetic degrees of freedom. This coupling is highly susceptible to atomistic
+defects. In this study, we investigated the magnetic phase of EuTiO$_3$
+epitaxial thin films via systematic defect engineering. A magnetic phase
+transition from an antiferromagnet to a ferromagnet was observed when the unit
+cell volume of EuTiO3 expanded due to the introduction of Eu-O vacancies.
+Optical spectroscopy and density functional theory calculations show that the
+change in the electronic structure as the ferromagnetic phase emerges can be
+attributed to the weakened Eu-Ti-Eu super-exchange interaction and the
+developed ferromagnetic Eu-O-Eu interaction. Facile defect engineering in
+EuTiO$_3$ thin films facilitates understanding and tailoring of their magnetic
+ground state.",2107.07711v1
+2022-05-22,Rashba spin-orbit interaction induced modulation of magnetic anisotropy,"In past few decades, Rashba spin-orbit coupling (SOC) has been successfully
+employed for the emergence of exotic phenomena at the quantum oxide interfaces.
+In these systems, the combined effect of charge transfer, broken symmetries and
+SOC yields intriguing interfacial magnetism and transport properties. Here, we
+provide an insight to control and tune interfacial phenomena in CaMnO3/CaIrO3
+based 3d-5d oxide heterostructures by the charge transfer driven Rashba SOC.
+Anomalous Hall effect in these canted antiferromagnetic heterostructures
+originates from the intrinsic contribution associated with the topology of the
+electronic band structure and it is mostly confined to the interface. Rashba
+SOC reconstructs the Berry curvature and enhances the anomalous Hall
+conductivity by two orders of magnitude. From the anisotropy magnetoresistance
+measurements we demonstrate that Rashba SOC is instrumental in tailoring
+magnetic anisotropy where magnetization easy-axis rotates from the out-of-plane
+direction to the in-plane direction. The ability to tune Rashba SOC and
+resulting competing magnetic anisotropy provides a route to manipulate
+electronic band structure for the origin of non-trivial spin texture useful for
+spin-orbitronics applications.",2205.10859v1
+2022-06-06,Strain-induced magnetization control in an oxide multiferroic heterostructure,"Controlling magnetism by using electric fields is a goal of research towards
+novel spintronic devices and future nano-electronics. For this reason,
+multiferroic heterostructures attract much interest. Here we provide
+experimental evidence, and supporting DFT analysis, of a transition in
+La0.65Sr0.35MnO3 (LSMO) thin film to a stable ferromagnetic phase, that is
+induced by the structural and strain properties of the ferroelectric BaTiO3
+(BTO) substrate, which can be modified by applying external electric fields.
+X-ray Magnetic Circular Dichroism (XMCD) measurements on Mn L edges with a
+synchrotron radiation show, in fact two magnetic transitions as a function of
+temperature that correspond to structural changes of the BTO substrate. We also
+show that ferromagnetism, absent in the pristine condition at room temperature,
+can be established by electrically switching the BTO ferroelectric domains in
+the out-of-plane direction. The present results confirm that electrically
+induced strain can be exploited to control magnetism in multiferroic oxide
+heterostructures.",2206.02864v1
+2023-01-12,Cryogenic temperature deposition of high-performance CoFeB/MgO/CoFeB magnetic tunnel junctions on 300 mm wafers,"We developed a cryogenic temperature deposition process for high-performance
+CoFeB/MgO/CoFeB magnetic tunnel junctions (MTJs) on 300 mm thermally oxidized
+silicon wafers. The effect of the deposition temperature of the CoFeB layers on
+the nanostructure, magnetic and magneto-transport properties of the MTJs were
+investigated in detail. When CoFeB was deposited at 100 K, the MTJs exhibited a
+perpendicular magnetic anisotropy (PMA) of 214 uJ/m2 and a voltage-controlled
+magnetic anisotropy (VCMA) coefficient of -45 fJ/Vm, corresponding to 1.4- and
+1.7-fold enhancements in PMA and VCMA, respectively, compared to the case of
+room-temperature deposition of CoFeB. The improvement in the MTJ properties was
+not simply due to the morphology of the MTJ films. The interface-sensitive
+magneto-transport properties indicated that interfacial qualities such as
+intermixing and oxidation states at the MgO/CoFeB interfaces were improved by
+the cryogenic temperature deposition. Cryogenic-temperature sputtering
+deposition is expected to be a standard manufacturing process for
+next-generation magnetoresistive random-access memory.",2301.04823v1
+2023-09-24,A Platform for Addressing Individual Magnetite Islands Grown Epitaxially on Ru(0001) and Manipulating Their Magnetic Domains,"We have grown high-quality magnetite micrometric islands on ruthenium stripes
+on sapphire through a combination of magnetron sputtering (Ru film),
+high-temperature molecular beam epitaxy (oxide islands), and optical
+lithography. The samples have been characterized by atomic force microscopy,
+Raman spectroscopy, X-ray absorption and magnetic circular dichroism in a
+photoemission microscope. The magnetic domains on the magnetite islands can be
+modified by the application of current pulses through the Ru stripes in
+combination with magnetic fields. The modification of the magnetic domains is
+explained by the Oersted field generated by the electrical current flowing
+through the stripes underneath the magnetite nanostructures. The fabrication
+method is applicable to a wide variety of rock salt and spinel oxides.",2309.14376v1
+2008-02-14,"Enhanced annealing, high Curie temperature and low-voltage gating in (Ga,Mn)As: A surface oxide control study","(Ga,Mn)As and related diluted magnetic semiconductors play a major role in
+spintronics research because of their potential to combine ferromagnetism and
+semiconducting properties in one physical system. Ferromagnetism requires
+~1-10% of substitutional Mn_Ga. Unintentional defects formed during growth at
+these high dopings significantly suppress the Curie temperature. We present
+experiments in which by etching the (Ga,Mn)As surface oxide we achieve a
+dramatic reduction of annealing times necessary to optimize the ferromagnetic
+film after growth, and report Curie temperature of 180 K at approximately 8% of
+Mn_Ga. Our study elucidates the mechanism controlling the removal of the most
+detrimental, interstitial Mn defect. The limits and utility of electrical
+gating of the highly-doped (Ga,Mn)As semiconductor are not yet established; so
+far electric-field effects have been demonstrated on magnetization with tens of
+Volts applied on a top-gate, field effect transistor structure. In the second
+part of the paper we present a back-gate, n-GaAs/AlAs/GaMnAs transistor
+operating at a few Volts. Inspired by the etching study of (Ga,Mn)As films we
+apply the oxide-etching/re-oxidation procedure to reduce the thickness (arial
+density of carriers) of the (Ga,Mn)As and observe a large enhancement of the
+gating efficiency. We report gatable spintronic characteristics on a series of
+anisotropic magnetoresistance measurements.",0802.2080v1
+2015-11-09,Proximity driven commensurate pinning in YBa2Cu3O7 through all-oxide magnetic nanostructures,"The design of artificial vortex pinning landscapes is a major goal towards
+large scale applications of cuprate superconductors. While disordered
+nanometric inclusions have shown to modify their vortex phase diagram and to
+produce enhancements of the critical current1,2, the effect of ordered oxide
+nanostructures remains essentially unexplored. This is due to the very small
+nanostructure size imposed by the short coherence length, and to the
+technological difficulties in the nanofabrication process. Yet, the novel
+phenomena occurring at oxide interfaces open a wide spectrum of technological
+opportunities to interplay with the superconductivity in cuprates. Here we show
+that the unusual long range suppression of the superconductivity occurring at
+the interface between manganites and cuprates affects vortex nucleation and
+provides a novel vortex pinning mechanism. In particular, we show evidence of
+commensurate pinning in YBCO films with ordered arrays of LCMO ferromagnetic
+nanodots. Vortex pinning results from the proximity induced reduction of the
+condensation energy at the vicinity of the magnetic nanodots, and yields an
+enhanced friction between the nanodot array and the moving vortex lattice in
+the liquid phase. This result shows that all-oxide ordered nanostructures
+constitute a powerful, new route for the artificial manipulation of vortex
+matter in cuprates.",1511.02750v1
+2016-03-06,"Controlling Dzyaloshinskii-Moriya Interaction via Chirality Dependent Layer Stacking, Insulator Capping and Electric Field","Using first-principle calculations, we demonstrate several approaches to
+manipulate Dzyaloshinskii-Moriya Interaction (DMI) in ultrathin magnetic films.
+First, we find that DMI is significantly enhanced when the ferromagnetic (FM)
+layer is sandwiched between nonmagnetic (NM) layers inducing additive DMI in
+NM/FM/NM structures. For instance, as Pt and Ir below Co induce DMI of opposite
+chirality, inserting Co between Pt (below) and Ir (above) in Ir/Co/Pt trilayers
+enhances the DMI of Co/Pt bilayers by 15\%. Furthermore, in case of Pb/Co/Pt
+trilayers (Ir/Fe/Co/Pt multilayers), DMI can be enhanced by 50\% (almost
+doubled) compared to Co/Pt bilayers reaching a very large DMI amplitude of 2.7
+(3.2) meV/atom. Our second approach for enhancing DMI is to use oxide capping
+layer. We show that DMI is enhanced by 60\% in Oxide/Co/Pt structures compared
+to Co/Pt bilayers. Moreover, we unveiled the DMI mechanism at Oxide/Co inerface
+due to interfacial electric field effect, which is different to Fert-Levy DMI
+at FM/NM interfaces. Finally, we demonstrate that DMI amplitude can be
+modulated using an electric field with efficiency factor comparable to that of
+the electric field control of perpendicular magnetic anisotropy in transition
+metal/oxide interfaces. These approaches of DMI controlling pave the way for
+skyrmions and domain wall motion-based spintronic applications.",1603.01847v2
+2017-09-05,Charge Localization and Ordering in A$_2$Mn$_8$O$_{16}$ Hollandite Group Oxides: Impact of Density Functional Theory Approaches,"The phases of A$_2$Mn$_8$O$_{16}$ hollandite group oxides emerge from the
+competition between ionic interactions, Jahn-Teller effects, charge ordering,
+and magnetic interactions. Their balanced treatment with feasible computational
+approaches can be challenging for commonly used approximations in Density
+Functional Theory. Three examples (A = Ag, Li and K) are studied with a
+sequence of different approximate exchange-correlation functionals. Starting
+from a generalized gradient approximation (GGA), an extension to include van
+der Waals interactions and a recently proposed meta-GGA are considered. Then
+local Coulomb interactions for the Mn $3d$ electrons are more explicitly
+considered with the DFT+$U$ approach. Finally selected results from a hybrid
+functional approach provide a reference. Results for the binding energy of the
+A species in the parent oxide highlight the role of van der Waals interactions.
+Relatively accurate results for insertion energies can be achieved with a low
+$U$ and a high $U$ approach. In the low $U$ case, the materials are described
+as band metals with a high symmetry, tetragonal crystal structure. In the high
+$U$ case, the electrons donated by A result in formation of local Mn$^{3+}$
+centers and corresponding Jahn-Teller distortions characterized by a local
+order parameter. The resulting degree of monoclinic distortion depends on
+charge ordering and magnetic interactions in the phase formed. The reference
+hybrid functional results show charge localization and ordering. Comparison to
+low temperature experiments of related compounds suggests that charge
+localization is the physically correct result for the hollandite group oxides
+studied here. . . .",1709.01390v1
+2019-11-13,Superparamagnetic iron oxide nanoparticles conjugated with doxorubicin for targeting breast cancer,"Development of the next generations of cancer therapy modalities is currently
+a crucial requirement of oncology. Advances in nanotechnology are bringing us
+closer to the development of dual and multifunctional nanoparticles that are
+challenging the traditional distinction between diagnostic and treatment
+agents. The chase of innovative, multifunctional, more efficient, and safer
+treatments is a major challenge in preclinical nanoparticle-mediated
+thermotherapeutic research for breast cancer. Here, we report that iron oxide
+nanoparticles have the dual capacity to act as both magnetic and drug delivery
+agents. The aim of this work was to investigate the in vitro effect of the
+loading of doxorubicin (DOX) on negatively charged polycarboxylic iron-oxide
+nanoparticles (SPIONs) and Rhodamine B functionalized SPIONs on breast
+carcinoma cell lines. For proper analysis and understanding of cell behavior
+after administration of DOX-SPIONs compared with free DOX, a complex set of in
+vitro tests, including production of MTT assay, cell cycle determination, and
+cellular uptake, were utilized. In summary, we have developed a magnetic
+nanoparticle-based drug delivery system that sequentially delivers the
+cytotoxic drug doxorubicin to breast cancer cells (MCF-7 and MDA-MB-231). The
+drug-coated nanoparticles, DOX-NPs, were assembled stepwise, with doxorubicin
+adsorbed to bare iron oxide nanoparticles first, by electrostatic reaction and
+allowed for the complexation of doxorubicin. In contrast, they were
+internalized to a much greater extent in MCF-7 and MDA-MB-231 cells and were
+cytotoxic due to the synergistic action of the two drugs and the effects of
+hyperthermia. The drug-coated particles were able to inhibit growth and
+proliferation of breast cancer cells in vitro, indicating that the system has
+potential to act as an antimetastatic chemothermotherapeutic agent.",1911.05378v1
+2023-10-10,"Soft-Chemical Synthesis, Structure Evolution, and Insulator-to-Metal Transition in a Prototypical Metal Oxide, λ-RhO$_2$","${\lambda}$-RhO$_2$, a prototype 4d transition metal oxide, has been prepared
+by oxidative delithiation of spinel LiRh$_2$O$_4$ using ceric ammonium nitrate.
+Average-structure studies of this RhO$_2$ polytype, including synchrotron
+powder X-ray diffraction and electron diffraction, indicate the room
+temperature structure to be tetragonal, in the space group I41/amd, with a
+first-order structural transition to cubic Fd-3m at T = 345 K on warming.
+Synchrotron X-ray pair distribution function analysis and $^7$Li solid state
+nuclear magnetic resonance measurements suggest that the room temperature
+structure displays local Rh-Rh bonding. The formation of these local dimers
+appears to be associated with a metal-to insulator transition with a
+non-magnetic ground state, as also supported by density functional theory-based
+electronic structure calculations. This contribution demonstrates the power of
+soft chemistry to kinetically stabilize a surprisingly simple binary oxide
+compound.",2310.07053v1
+2015-10-16,Enhanced orbital magnetic moments in magnetic heterostructures with interface perpendicular magnetic anisotropy,"We have studied the magnetic layer thickness dependence of the orbital
+magnetic moment in magnetic heterostructures to identify contributions from
+interfaces. Three different heterostructures, Ta/CoFeB/MgO, Pt/Co/AlO$_x$ and
+Pt/Co/Pt, which possess significant interface contribution to the perpendicular
+magnetic anisotropy, are studied as model systems. X-ray magnetic circular
+dichroism spectroscopy is used to evaluate the relative orbital moment, i.e.
+the ratio of the orbital to spin moments, of the magnetic elements constituting
+the heterostructures. We find that the relative orbital moment of Co in
+Pt/Co/Pt remains constant against its thickness whereas the moment increases
+with decreasing Co layer thickness for Pt/Co/AlO$_x$, suggesting that a
+non-zero interface orbital moment exists for the latter system. For
+Ta/CoFeB/MgO, a non-zero interface orbital moment is found only for Fe. X-ray
+absorption spectra shows that a particular oxidized Co state in Pt/Co/AlO$_x$,
+absent in other heterosturctures, may give rise to the interface orbital moment
+in this system. These results show element specific contributions to the
+interface orbital magnetic moments in ultrathin magnetic heterostructures.",1510.04756v1
+2017-01-16,Dynamics of magnetic nano particles in a viscous fluid driven by rotating magnetic fields,"The rotational dynamics of magnetic nano particles in rotating magnetic
+fields in the presence of thermal noise is studied both theoretically and by
+performing numerical calculations. Kinetic equations for the dynamics of
+particles with uniaxial magnetic anisotropy are studied and the phase lag
+between the rotating magnetic moment and the driving field is obtained. It is
+shown that for large enough anisotropy energy the magnetic moment is locked to
+the anisotropy axis so that the particle behaves like a rotating magnetic
+dipole. The corresponding rigid dipole model is analyzed both numerically by
+solving the appropriate Fokker-Planck equation and analytically by applying an
+effective field method. In the special case of a rotating magnetic field
+applied analytic results are obtained in perfect agreement with numerical
+results based on the Fokker-Planck equation. The analytic formulas derived are
+not restricted to small magnetic fields or low frequencies and are therefore
+important for applications. The illustrative numerical calculations presented
+are performed for magnetic parameters typical for iron oxide.",1702.04673v1
+2021-01-26,Understanding Magnetism in Double Double Perovskites: A Complex Multiple Magnetic Sublattice System,"Understanding magnetism in multiple magnetic sublattice system, driven by the
+interplay of varied nature of magnetic exchanges, is on one hand challenging
+and on other hand intriguing. Motivated by the recent synthesis of AA'BB'O_6
+double double perovskites with multiple magnetic ions both at A- and B-sites,
+we investigate the mechanism of magnetic behavior in these interesting class of
+compounds. We find that the magnetism in such multiple sublattice compounds is
+governed by the interplay and delicate balance between two distinct mechanisms,
+a) kinetic energy-driven multiple sublattice double exchange mechanism and b)
+the conventional super-exchange mechanism. The derived spin Hamiltonian based
+on first-principles calculations is solved by the classical Monte Carlo
+technique which reproduces the observed magnetic properties. Finally, the
+influence of off-stoichiometry, as in experimental samples, is discussed. Some
+of these double double perovskite compounds are found to possess large total
+magnetic moment and also are found to be half-metallic, which raises the hope
+of future applications of these large magnetic moment half-metallic oxides in
+spintronics and memory devices.",2101.10822v1
+2024-04-01,"Harnessing Interlayer Magnetic Coupling for Efficient, Field-Free Current-Induced Magnetization Switching in a Magnetic Insulator","Owing to the unique features of low Gilbert damping, long spin-diffusion
+lengths and zero Ohmic losses, magnetic insulators are promising candidate
+materials for next-generation spintronic applications. However, due to the
+localized magnetic moments and the complex metal-oxide interface between
+magnetic insulators and heavy metals, spin-functional Dzyaloshinskii-Moriya
+interactions or spin Hall and Edelstein effects are weak, which diminishes the
+performance of these typical building blocks for spintronic devices. Here, we
+exploit the exchange coupling between metallic and insulating magnets for
+efficient electrical manipulation of heavy metal/magnetic insulator
+heterostructures. By inserting a thin Co layer, we enhance the spin-orbit
+torque efficiency by more than 20 times, which significantly reduces the
+switching current density. Moreover, we demonstrate field-free current-induced
+magnetization switching caused by a symmetry-breaking non-collinear magnetic
+texture. Our work launches magnetic insulators as an alternative platform for
+low-power spintronic devices.",2404.00845v1
+2011-07-21,Short-range spin order and frustrated magnetism in Mn2InSbO6 and Mn2ScSbO6,"The complex metal oxides Mn2ASbO6 (A=In, Sc) with a corundum-related
+structure A3BO6 have been prepared as polycrystalline powders by a solid state
+reaction route. The crystal structure and magnetic properties have been
+investigated using a combination of X-ray and neutron powder diffraction,
+electron microscopy, calorimetric and magnetic measurements. At room
+temperature these compounds adopt a trigonal structure, space group R-3 with a
+= 8.9313(1) {\AA}, c = 10.7071(2) {\AA} (for In) and a = 8.8836(1) {\AA}, c =
+10.6168(2) {\AA} (for Sc) which persists down to 1.6 K. The Mn and A cations
+were found to be randomly distributed over the A-sites. The overall behavior of
+the magnetization of Mn2InSbO6 and Mn2ScSbO6 is quite similar. In spite of the
+relatively large amount of Mn ions on the A-site, only short-ranged magnetism
+is observed. Neutron diffraction patterns of Mn2InSbO6 showed no evidence of a
+long-range magnetic ordering at 1.6 K, instead only a weak diffuse magnetic
+peak was observed at low temperatures. The factors governing the observed
+structural and magnetic properties of Mn2ASbO6 are discussed and compared with
+those of other Mn-containing complex metal oxides with a corundum-related
+structure. The influence of the A-cation sublattice on magnetic properties is
+also considered.",1107.4206v1
+2023-06-27,Permanent magnet systems to study the interaction between magnetic nanoparticles and cells in microslide channels,"We optimized designs of permanent magnet systems to study the effect of
+magnetic nanoparticles on cell cultures in microslide channels. This produced
+two designs, one of which is based on a large cylindrical magnet that applies a
+uniform force density of 6 MN/m$^3$ on soft magnetic iron-oxide spherical
+nanoparticles at a field strength of over 300 mT. We achieved a force
+uniformity of better than 14% over the channel area leading to a concentration
+variation that was below our measurement resolution. The second design was
+aimed at maximizing the force by using a Halbach array. We indeed increased the
+force by more than one order of magnitude at force density values over 400
+MN/m$^3$, but at the cost of uniformity. However, the latter system can be used
+to trap magnetic nanoparticles efficiently and to create concentration
+gradients. We demonstrated both designs by analyzing the effect of magnetic
+forces on the cell viability of human hepatoma HepG2 cells in the presence of
+bare Fe$_2$O$_3$ and cross-linked dextran iron-oxide cluster-type particles
+(MicroMod). Python scripts for magnetic force calculations and particle
+trajectory modeling as well as source files for 3D prints have been made
+available so these designs can be easily adapted and optimized for other
+geometries.",2306.15459v2
+2023-11-22,Effects of magnetic fields and orbital angular momentum on excitonic condensation in two-orbital Hubbard model,"We investigate the magnetic-field effects on a two-orbital Hubbard model that
+describes multiple spin states. Cobalt oxides have been investigated as
+materials possessing spin-state degrees of freedom due to the interplay between
+the Hund coupling interaction and crystalline field effect. In the competing
+region, quantum hybridizations between distinct spin states are expected to
+emerge, corresponding to excitonic condensation. Applied magnetic fields could
+also induce such a competition. To understand magnetic-field effects on
+excitonic condensation in multi-orbital systems, it is crucial to account for
+contributions from both spin and orbital degrees of freedom to magnetic
+properties. Here, we study field-induced phenomena in the two-orbital Hubbard
+model by focusing on the role of the orbital angular momentum. We
+comprehensively analyze this model on a square lattice employing the
+Hartree-Fock approximation. Omitting contributions from the orbital moment, we
+find that an applied magnetic field gives rise to two excitonic phases, besides
+the spin-state ordered phase, between the nonmagnetic low-spin and
+spin-polarized high-spin phases. One of these excitonic phases manifests a
+staggered-type spin-state order, interpreted as an excitonic supersolid state.
+Conversely, the other phase is not accompanied by it and exhibits only a spin
+polarization due to the applied magnetic field. When spin-orbit coupling is
+present, this phase displays a ferrimagnetic spin alignment attributed to spin
+anisotropy. Our analysis also reveals that incorporating the contribution of
+the orbital magnetic moment to the Zeeman term significantly alters the overall
+structure of the phase diagram. Notably, the orbital magnetization destabilizes
+the excitonic phase in contrast to scenarios without this contribution. We also
+discuss the relevance of our findings to real materials, such as cobalt oxides.",2311.13191v1
+2024-03-06,The role of interfacial interactions and oxygen vacancies in tuning magnetic anisotropy in LaCrO$_{3}$/LaMnO$_{3}$ heterostructures,"The interplay of lattice, electronic, and spin degrees of freedom at
+epitaxial complex oxide interfaces provides a route to tune their magnetic
+ground states. Unraveling the competing contributions is critical for tuning
+their functional properties. We investigate the relationship between magnetic
+ordering and magnetic anisotropy and the lattice symmetry, oxygen content, and
+film thickness in compressively strained LaMnO$_3$/LaCrO$_3$ superlattices.
+Mn-O-Cr antiferromagnetic superexchange interactions across the heterointerface
+resulting in a net ferrimagnetic magnetic structure. Bulk magnetometry
+measurements reveal isotropic in-plane magnetism for as-grown oxygen-deficient
+thinner thin samples due to equal fractions of orthorhombic a+a-c-, and a-a+c-
+twin domains. As the superlattice thickness is increased, in-plane magnetic
+anisotropy emerges as the fraction of the a+a-c- domain increases. On annealing
+in oxygen, the suppression of oxygen vacancies results in a contraction of the
+lattice volume, and an orthorhombic to rhombohedral transition leads to
+isotropic magnetism independent of the film thickness. The complex interactions
+are investigated using high-resolution synchrotron diffraction and X-ray
+absorption spectroscopy. These results highlight the role of the evolution of
+structural domains with film thickness, interfacial spin interactions, and
+oxygen-vacancy-induced structural phase transitions in tuning the magnetic
+properties of complex oxide heterostructures.",2403.03764v1
+2020-01-08,Non-equilibrium spin dynamics in the temperature and magnetic field dependence of magnetization curves of ferrimagnetic Co$_{1.75}$Fe$_{1.25}$O$_4$ and its composite with BaTiO$_3$,"A comparative study of the non-equilibrium magnetic phenomena (magnetic
+blocking, memory, exchange bias and aging effect) has been presented for
+ferrimagnetic Co$_{1.75}$Fe$_{1.25}$O$_4$ (CFO) and its composite with
+non-magnetic BaTiO$_3$ (BTO). Synchrotron X-Ray diffraction patterns have
+confirmed coexistence of CFO and BTO structures in composite, but magnetic spin
+dynamics have been remarkably modified. The blocking phenomenon of
+ferrimagnetic domains below the room temperature has been studied by different
+modes of (zero field cooled and field cooled) magnetic measurements in
+collaboration with magnetic fields ON and OFF modes and time dependent
+magnetization. The applications of unconventional protocols during time
+dependent magnetization measurement at different stages of the temperature and
+field dependence of the magnetization curves have been useful to reveal the
+non-equilibrium dynamics of magnetic spin order. The applying of off-field
+relaxation experiments has made possible to tune the magnetic state and
+coercivity of the systems. The role of interfacial coupling between magnetic
+and non-magnetic particles has been understood on different magnetic phenomena
+(meta-stable magnetic state, exchange bias and memory effect) by comparing the
+experimental results of Co$_{1.75}$Fe$_{1.25}$O$_4$ spinel oxide and its
+composite with BaTiO$_3$ particles.",2001.02602v2
+2022-05-13,Isotropic orbital magnetic moments in magnetically anisotropic SrRuO3 films,"Epitaxially strained SrRuO3 films have been a model system for understanding
+the magnetic anisotropy in metallic oxides. In this paper, we investigate the
+anisotropy of the Ru 4d and O 2p electronic structure and magnetic properties
+using high-quality epitaxially strained (compressive and tensile) SrRuO3 films
+grown by machine-learning-assisted molecular beam epitaxy. The element-specific
+magnetic properties and the hybridization between the Ru 4d and O 2p orbitals
+were characterized by Ru M2,3-edge and O K-edge soft X-ray absorption
+spectroscopy and X-ray magnetic circular dichroism measurements. The
+magnetization curves for the Ru 4d and O 2p magnetic moments are identical,
+irrespective of the strain type, indicating the strong magnetic coupling
+between the Ru and O ions. The electronic structure and the orbital magnetic
+moment relative to the spin magnetic moment are isotropic despite the
+perpendicular and in-plane magnetic anisotropy in the compressive-strained and
+tensile-strained SrRuO3 films; i.e., the orbital magnetic moments have a
+negligibly small contribution to the magnetic anisotropy. This result
+contradicts Bruno model, where magnetic anisotropy arises from the difference
+in the orbital magnetic moment between the perpendicular and in-plane
+directions. Contributions of strain-induced electric quadrupole moments to the
+magnetic anisotropy are discussed, too.",2205.06563v1
+2023-06-16,Tailoring defects and nanocrystal transformation for optimal heating power in bimagnetic $Co_yFe_{1-y}O@Co_xFe_{3-x}O_4$ particles,"The effects of cobalt incorporation in spherical heterostructured iron oxide
+nanocrystals (NCs) of sub-critical size have been explored by colloidal
+chemistry methods. Synchrotron X-ray total scattering methods suggest that
+cobalt (Co) substitution in rock salt iron oxide NCs tends to remedy its vacant
+iron sites, offering a higher degree of resistance to oxidative conversion.
+Self-passivation still creates a spinel-like shell, but with higher volume
+fraction of the rock salt Co-containing phase in the core. The higher divalent
+metal stoichiometry in the rock salt phase, with increasing Co content, results
+in a population of unoccupied tetrahedral metal sites in the spinel part,
+likely through oxidative shell creation, involving an ordered defect-clustering
+mechanism, directly correlated to the core stabilization. To shed light on the
+effects of Co-substitution and atomic-scale defects (vacant sites), Monte Carlo
+simulations suggest that designed NCs, with desirable, enhanced magnetic
+properties (cf. exchange bias and coercivity), are developed with
+magnetocrystalline anisotropy raised at relatively low content of Co ions in
+the lattice. Growth of optimally performing candidates combines also a strongly
+exchange-coupled system, secured through a high volumetric ratio rock salt
+phase, interfaced by a not so defective spinel shell. In view of these
+requirements, Specific Absorption Rate (SAR) calculations demonstrate that the
+sufficiently protected from oxidation rock salt core and preserved over time
+heterostructure, play a key role in magnetically-mediated heating efficacies,
+for potential use of such NCs in magnetic hyperthermia applications.",2306.09684v1
+2018-03-20,Direct demonstration of the emergent magnetism resulting from the multivalence Mn in a LaMnO3 epitaxial thin film system,"Atomically engineered oxide heterostructures provide a fertile ground for
+creating novel states. For example, a two-dimensional electron gas at the
+interface between two oxide insulators, giant thermoelectric Seebeck
+coefficient, emergent ferromagnetism from otherwise nonmagnetic components, and
+colossal ionic conductivity. Extensive research efforts reveal that oxygen
+deficiency or lattice strain play an important role in determining these
+unexpected properties. Herein, by studying the abrupt presence of robust
+ferromagnetism (up to 1.5 uB/Mn) in LaMnO3-based heterostructures, we find the
+multivalence states of Mn that play a decisive role in the emergence of
+ferromagnetism in the otherwise antiferromagnetic LaMnO3 thin films. Combining
+spatially resolved electron energy-loss spectroscopy, X-ray absorption
+spectroscopy and X-ray magnetic circular dichroism techniques, we determine
+unambiguously that the ferromagnetism results from a conventional Mn3+-O-Mn4+
+double-exchange mechanism rather than an interfacial effect. In contrast, the
+magnetic dead layer of 5 unit cell in proximity to the interface is found to be
+accompanied with the accumulation of Mn2+ induced by electronic reconstruction.
+These findings provide a hitherto-unexplored multivalence state of Mn on the
+emergent magnetism in undoped manganite epitaxial thin films, such as LaMnO3
+and BiMnO3, and shed new light on all-oxide spintronic devices.",1803.07402v1
+2022-12-20,Chemical Design of Electronic and Magnetic Energy Scales in Tetravalent Praseodymium,"Lanthanides in the trivalent oxidation state are typically described using an
+ionic picture that leads to localized magnetic moments. The hierarchical energy
+scales associated with trivalent lanthanides produce desirable properties for
+e.g., molecular magnetism, quantum materials, and quantum transduction. Here,
+we show that this traditional ionic paradigm breaks down for praseodymium in
+the 4+ oxidation state. Synthetic, spectroscopic, and theoretical tools
+deployed on several solid-state Pr4+ oxides uncover the unusual participation
+of 4f orbitals in bonding and the anomalous hybridization of the 4f1
+configuration with ligand valence electrons, analogous to transition metals.
+The resulting competition between crystal-field and spin-orbit-coupling
+interactions fundamentally transforms the spin-orbital magnetism of Pr4+, which
+departs from the Jeff =1/2 limit and resembles that of high-valent actinides.
+Our results show that Pr4+ ions are in a class on their own, where the
+hierarchy of single-ion energy scales can be tailored to explore new correlated
+phenomena in quantum materials.",2212.10401v1
+2023-06-11,Visualizing magnetic field-induced rotational electronic symmetry breaking in a spinel oxide superconductor,"The spinel oxide superconductor LiTi2O4 (LTO) is an intriguing material
+platform where the electronic structure near the Fermi energy (EF) is derived
+from 3d elections on the geometrically frustrated Ti pyrochlore network. A
+recent angle-resolved photoemission spectroscopy (ARPES) study has revealed the
+existence of an exotic quasiparticle state arising from the competition between
+instability towards orbital ordering and geometrical frustration below 150 K.
+An intriguing remaining challenge is the imaging of Abrikosov vortices, which
+generally inherits the symmetry of the Fermi surface at k_z=0. Here, we observe
+surprising triangular-shaped Abrikosov vortices on an LTO(111) film, deviating
+from the conventional expectations of the six-fold symmetric Fermi surface at
+k_z=0. In combination with the experimentally observed isotropic pairing, we
+propose magnetic field-driven rotational electronic symmetry breaking of the
+underlying Fermi surface. Consequently, we observe Josephson vortices along the
+crystalline domain boundary, across which quasiparticle hopping is suppressed
+due to the symmetry-broken Fermi surface in each domain. Our discoveries point
+to the existence of unique physics of magnetic field-induced electronic
+rotational symmetry breaking in the spinel oxide superconductor LTO. This
+picture is in stark contrast to the other exotic superconductors with partial
+gap opening or long-range ordering with broken symmetry above the
+superconducting critical temperature at zero magnetic field.",2306.06711v1
+2002-11-09,Magnetic order and superconductivity in LSCO: a review,"High-Tc copper oxides of the LSCO family show a very clear case of
+competition between antiferromagnetic (AF) order and superconductivity.
+Magnetic order can, however, coexist with superconductivity, and the
+experimental evidence for frozen magnetic moments in superconducting samples is
+reviewed here. The primary characteristics of the magnetic order are summarized
+and some open questions are outlined, particularly concerning the intrinsic or
+extrinsic nature of this order around x=0.12.",0211178v1
+2002-12-17,Unconventional magnetic transition and transport behavior in Na0.75CoO2,"Here we report an unconventional magnetic and transport phenomenon in a
+layered cobalt oxide, NaxCoO2. Only for x = 0.75, a magnetic transition of the
+second order was clearly detected at Tm ~ 22 K where an apparent specific-heat
+jump, an onset of extremely small spontaneous magnetization, and a kink in
+resistivity came in. Moreover large positive magnetoresistance effect was
+observed below Tm. These features of the transition strongly indicate the
+appearance of an unusual electronic state that may be attributed to the
+strongly-correlated electrons in Na0.75CoO2.",0212395v1
+2003-07-12,"Magnetic and microwave properties of (Ni,Co)Fe2O4-ferroelectric and (La,Ca,Sr)MnO3-ferroelectric multilayer structures","Structural, magnetic and ferromagnetic resonance characterization studies
+have been performed on lay-ered ferromagnetic-ferroelectric oxides that show
+strong magnetoelectric coupling. The samples contained thick films of ferrites
+or substituted lanthanum manganites for the ferromagnetic phase and lead
+zirconate titanate for the ferroelectric phase, and were sintered high
+temperatures. Results indicate defect free ferrites, but deterioration of
+manganite parameters due to diffusion at the interface and accounts for poor
+magnetoelectric coupling in manganite-PZT samples.",0307302v1
+2003-07-17,"Specific heat and magnetization study on single crystals of a frustrated, quasi one-dimensional oxide: Ca3Co2O6","Specific heat and magnetization measurements have been carried out under a
+range of magnetic fields on single crystals of Ca3Co2O6. This compound is
+composed of Ising magnetic chains that are arranged on a triangular lattice.
+The intrachain and interchain couplings are ferromagnetic and
+antiferromagnetic, respectively. This situation gives rise to geometrical
+frustration, that bears some similarity to the classical problem of a
+two-dimensional Ising triangular antiferromagnet. This paper reports on the
+ordering process at low-T and the possibility of one-dimensional features at
+high-T.",0307429v1
+2003-09-16,Field-Induced Magnetization Steps in Intermetallic Compounds and Manganese Oxides: The Martensitic Scenario,"Field-induced magnetization jumps with similar characteristics are observed
+at low temperature for the intermetallic germanide Gd5Ge4and the mixed-valent
+manganite Pr0.6Ca0.4Mn0.96Ga0.04O3. We report that the field location -and even
+the existence- of these jumps depends critically on the magnetic field sweep
+rate used to record the data. It is proposed that, for both compounds, the
+martensitic character of their antiferromagnetic-to-ferromagnetic transitions
+is at the origin of the magnetization steps.",0309389v1
+2004-03-16,Rashba Effect at Magnetic Metal Surfaces,"We give experimental and theoretical evidence of the Rashba effect at the
+magnetic rare-earth metal surface Gd(0001). The Rashba effect is substantially
+enhanced and the Rashba parameter changes its sign when a metal-oxide surface
+layer is formed. The experimental observations are quantitatively described by
+ab initio calculations that give a detailed account of the near-surface charge
+density gradients causing the Rashba effect. Since the sign of the Rashba
+splitting depends on the magnetization direction, the findings open up new
+opportunities for the study of surface and interface magnetism.",0403405v2
+2004-03-29,"Ground state, electronic structure and magnetism of LaMnO3","We have calculated the discrete low-energy electronic structure in LaMnO3
+originating from the atomic-like states of the strongly correlated 3d4
+electronic system occurring in the Mn3+ ion. We take into account very strong
+intra-atomic correlations, crystal field interactions and the intra-atomic
+spin-orbit coupling. We calculated magnetic and paramagnetic state of LaMnO3
+within the consistent description given by Quantum Atomistic Solid State Theory
+(QUASST). Our studies indicate that the intra-atomic spin-orbit coupling and
+the orbital magnetism are indispensable for the physically adequate description
+of electronic and magnetic properties of LaMnO3.
+  Keywords: 3d oxides, crystal field, spin-orbit coupling, LaMnO3
+  PACS: 71.70Ej, 75.10Dg",0403714v1
+2006-08-23,A New Multiferroic Material: MnWO4,"We report the multiferroic behaviour of MnWO$_4$, a magnetic oxide with
+monoclinic crystal structure and spiral long-range magnetic order. Based upon
+recent theoretical predictions MnWO$_4$ should exhibit ferroelectric
+polarization coexisting with the proper magnetic structure. We have confirmed
+the multiferroic state below 13 K by observing a finite electrical polarization
+in the magnetically ordered state via pyroelectric current measurements.",0608498v1
+2007-11-05,Magnetic excitations in vanadium spinels,"We study magnetic excitations in vanadium spinel oxides AV$_2$O$_4$ (A=Zn,
+Mg, Cd) using two models: first one is a superexchange model for vanadium S=1
+spins, second one includes in addition spin-orbit coupling, and crystal
+anisotropy. We show that the experimentally observed magnetic ordering can be
+obtained in both models, however the orbital ordering is different with and
+without spin-orbit coupling and crystal anisotropy. We demonstrate that this
+difference strongly affects the spin-wave excitation spectrum above the
+magnetically ordered state, and argue that the neutron measurement of such
+dispersion is a way to distinguish between the two possible orbital orderings
+in AV$_2$O$_4$.",0711.0732v1
+2008-04-21,Unusual magnetic behavior in ferrite hollow nanospheres,"We report unusual magnetic behavior in iron oxide hollow nanospheres of 9.3
+$nm$ in diameter. The large fraction of atoms existing at the inner and outer
+surfaces gives rise to a high magnetic disorder. The overall magnetic behavior
+can be explained considering the coexistence of a soft superparamagnetic phase
+and a hard phase corresponding to the highly frustrated cluster-glass like
+phase at the surface regions.",0804.3292v1
+2009-11-10,Anomalous magnetic behavior of CuO nanoparticles,"We report studies on temperature, field and time dependence of magnetization
+on cupric oxide nanoparticles of sizes 9 nm, 13 nm and 16 nm. The nanoparticles
+show unusual features in comparison to other antiferromagnetic nanoparticle
+systems. The field cooled (FC) and zero field cooled (ZFC) magnetization curves
+bifurcate well above the N\'eel temperature and the usual peak in the ZFC
+magnetization curve is absent.
+  The system does not show any memory effects which is in sharp contrast to the
+usual behavior shown by other antiferromagnetic nanoparticles. It turns out
+that the non-equilibrium behavior of CuO nanoparticles is very strange and is
+neither superparamagnetic nor spin glass-like.",0911.1838v2
+2011-03-09,Antiferromagnetic Heisenberg S=5/2 spin chain compound SrMn$_2$V$_2$O$_8$,"Large single crystals of the new compound SrMn$_2$V$_2$O$_8$ have been grown
+by the floating-zone method. This transition-metal based oxide is isostructural
+to SrNi$_2$V$_2$O$_8$, described by the tetragonal space group $I4_1cd$.
+Magnetic properties were investigated by means of susceptibility,
+magnetization, and specific heat measurements. The title compound behaves like
+a one-dimensional magnetic system above the ordering temperature ($T_N$ = 43
+K). The magnetic ground state can be described as a classical long-range
+ordered antiferromagnet with weak anisotropy.",1103.1830v1
+2011-06-16,Thermomagnonic spin transfer and Peltier effects in insulating magnets,"We study the coupled magnon energy transport and collective magnetization
+dynamics in ferromagnets with magnetic textures. By constructing a
+phenomenological theory based on irreversible thermodynamics, we describe
+motion of domain walls by thermal gradients and generation of heat flows by
+magnetization dynamics. From microscopic description based on magnon kinetics,
+we estimate the transport coefficients and analyze the feasibility of
+energy-related applications in insulating ferromagnets, such as yttrium iron
+garnet and europium oxide.",1106.3135v2
+2011-12-16,"Comment on ""Unconventional Magnetism in a Nitrogen-Containing Analog of Cupric Oxide""","In a recent Letter [PRL, 107, 047208 (2011)], Zorko et al. report on an
+""unexpected inhomogeneous magnetism"" related to ""a peculiar fragility"" of the
+resonating-valence-bond (RVB) electronic state in the spin-1/2 quantum magnet
+CuNCN. Here, we show that: i) the spin model of the anisotropic triangular
+lattice (ATL), as proposed by Zorko et al., does not apply to CuNCN; ii) this
+model does not support the proclaimed RVB ground state in the relevant
+parameter range; iii) the magnetic state of CuNCN is not necessarily
+inhomogeneous.",1112.3894v1
+2012-09-14,Magnetic Order and Charge Disproportionation in a Spin-ice type Kondo Lattice Model: Large Scale Monte Carlo Study,"Phase diagram of a spin-ice type Kondo lattice model, potentially relevant to
+metallic pyrochlore oxides, is obtained by the Monte Carlo simulation
+implementing the polynomial expansion technique up to the system size with 2048
+sites. We identified a new 32-sublattice magnetic phase with concomitant charge
+disproportionation, along with other phases such as two-in two-out and
+all-in/all-out orders. The spin and charge pattern can be switched by external
+magnetic field to a different one accompanied by a half magnetization plateau.",1209.3134v1
+2016-04-15,Electron magnetic resonance in magnetic nanoparticles: dependence on the particle size and applicability of the modified giant spin model,"Superparamagnetic nanoparticles containing hundreds and thousands of coupled
+electron spins are on the boundary between classical and quantum behavior, and
+demonstrate features which are typical for paramagnetic spins and absent in
+macroscopic ferromagnetic systems. In order to better understand the evolution
+of magnetization dynamics from quantum to classical behavior with the increase
+in the system size, we study the electron magnetic resonance signal in
+suspensions of iron oxide nanoparticles as the function of the particle size.
+The experimental data are compared with numerical simulations based on the
+giant spin approach.",1604.04594v2
+2001-02-23,Holes in a Quantum Spin Liquid,"Magnetic neutron scattering provides evidence for nucleation of
+antiferromagnetic droplets around impurities in a doped nickel-oxide based
+quantum magnet. The undoped parent compound contains a spin liquid with a
+cooperative singlet ground state and a gap in the magnetic excitation spectrum.
+Calcium doping creates excitations below the gap with an incommensurate
+structure factor. We show that weakly interacting antiferromagnetic droplets
+with a central phase shift of $\pi$ and a size controlled by the correlation
+length of the quantum liquid can account for the data. The experiment provides
+a first quantitative impression of the magnetic polarization cloud associated
+with holes in a doped transition metal oxide.",0102445v2
+2001-10-12,Crystal Structure and Magnetism of the Linear-Chain Copper Oxides Sr5Pb3-xBixCuO12,"The title quasi-1D copper oxides (0=< x =<0.4) were investigated by neutron
+diffraction and magnetic susceptibility studies. Polyhedral CuO4 units in the
+compounds were found to comprise linear-chains at inter-chain distance of
+approximately 10 A. The parent chain compound (x = 0), however, shows less
+anisotropic magnetic behavior above 2 K, although it is of substantially
+antiferromagnetic (mu_{eff}= 1.85 mu_{B} and Theta_{W} = -46.4 K) spin-chain
+system. A magnetic cusp gradually appears at about 100 K in T vs chi with the
+Bi substitution. The cusp (x = 0.4) is fairly characterized by and therefore
+suggests the spin gap nature at Delta/k_{B} ~ 80 K. The chain compounds hold
+electrically insulating in the composition range.",0110262v1
+2001-10-22,Commensurate and Incommensurate Phases of a Spin-Peierls System,"The interest in the study of spin-Peierls phenomenon has increased with the
+discovery of copper germanium oxide (CuGeO_3) as an example of spin-Peierls
+systems. The availability of this inorganic compound as large, high quality
+single crystals, allow experimental measurements which aid in understanding the
+spin-Peierls phenomenon. This report details the numerical and analytical work
+done on the various magnetic phases that occur in a quasi-one-dimensional
+spin-Peierls system (like that of copper germanium oxide). Taking the system to
+be finite, the bond displacements, single particle energies, energy
+eigenfunctions, spin densities and phonon frequencies are calculated
+numerically for all possible magnetizations, which includes both the
+commensurate and incommensurate phases, at zero temperature. Solitons of
+fractional spin are found to be present in the system for appropriate
+magnetizations. The uniform to dimerized phase transition occurring in this
+system is also modelled numerically. The single particle and ground-state
+energies are later obtained theoretically for the uniform and dimerized phases.
+In addition, the lattice spin displacements are analytically modelled for a
+particular magnetization of the system.",0110446v1
+2003-07-17,Specific heat investigation of the magnetic ordering in two frustrated spin-chain oxides: Ca3Co2O6 and Ca3CoRhO6,"Specific heat measurements were carried out on the closely related spin-chain
+oxides Ca3Co2O6 and Ca3CoRhO6. Both compounds consist of Ising magnetic chains
+that are arranged on a triangular lattice. The spin coupling along and between
+the chains are ferromagnetic and antiferromagnetic, respectively. Geometrical
+frustration is expected from the combination of these magnetic features. The
+present study reports that the specific heat data of these compounds exhibit
+similarities in the spin-freezing process at low T, whereas striking
+differences exist in the antiferromagnetic interchain ordering at higher T.
+These results are discussed in connection with previous magnetization and
+neutron diffraction data.",0307433v1
+2004-06-21,"Orbital ordering and one-dimensional magnetic correlation in vanadium spinel oxides AV2O4 (A = Zn, Mg, or Cd)","We present our theoretical results on the mechanism of two transitions in
+vanadium spinel oxides $A$V$_2$O$_4$ ($A$=Zn, Mg, or Cd) in which magnetic V
+cations constitute a geometrically-frustrated pyrochlore structure. We have
+derived an effective spin-orbital-lattice coupled model in the strong
+correlation limit of the multiorbital Hubbard model, and applied Monte Carlo
+simulation to the model. The results reveal that the higher-temperature
+transition is a layered antiferro-type orbital ordering accompanied by
+tetragonal Jahn-Teller distortion, and the lower-temperature transition is an
+antiferromagnetic spin ordering. The orbital order lifts the magnetic
+frustration partially, and induces spatial anisotropy in magnetic exchange
+interactions. In the intermediate phase, the system can be considered to
+consist of weakly-coupled antiferromagnetic chains lying in the perpendicular
+planes to the tetragonal distortion.",0406462v1
+2004-09-10,Novel Reconfigurable Logic Gates Using Spin Metal-Oxide-Semiconductor Field-Effect Transistors,"We propose and numerically simulate novel reconfigurable logic gates
+employing spin metal-oxide-semiconductor field-effect transistors (spin
+MOSFETs). The output characteristics of the spin MOSFETs depend on the relative
+magnetization configuration of the ferromagnetic contacts for the source and
+drain, that is, high current-drive capability in the parallel magnetization and
+low current-drive capability in the antiparallel magnetization [S. Sugahara and
+M. Tanaka: Appl. Phys. Lett. 84 (2004) 2307]. A reconfigurable NAND/NOR logic
+gate can be realized by using a spin MOSFET as a driver or an active load of a
+complimentary MOS (CMOS) inverter with a neuron MOS input stage. Its logic
+function can be switched by changing the relative magnetization configuration
+of the ferromagnetic source and drain of the spin MOSFET. A reconfigurable
+logic gate for all symmetric Boolean functions can be configured using only
+five CMOS inverters including four spin MOSFETs. The operation of these
+reconfigurable logic gates was confirmed by numerical simulations using a
+simple device model for the spin MOSFETs",0409262v1
+2008-02-25,Onset of Magnetic Order in Strongly-Correlated Systems from ab initio Electronic Structure Calculations: Application to Transition Metal Oxides,"We describe an ab initio theory of finite temperature magnetism in
+strongly-correlated electron systems. The formalism is based on spin density
+functional theory, with a self-interaction corrected local spin density
+approximation (SIC-LSDA). The self-interaction correction is implemented
+locally, within the KKR multiple-scattering method. Thermally induced magnetic
+fluctuations are treated using a mean-field `disordered local moment' (DLM)
+approach and at no stage is there a fitting to an effective Heisenberg model.
+We apply the theory to the 3d transition metal oxides, where our calculations
+reproduce the experimental ordering tendencies, as well as the qualitative
+trend in ordering temperatures. We find a large insulating gap in the
+paramagnetic state which hardly changes with the onset of magnetic order.",0802.3660v2
+2009-04-03,A radical approach to promote multiferroic coupling in double perovskites,"Double perovskites provide a unique opportunity to induce and control
+multiferroic behaviors in oxide systems. The appealing possibility to design
+materials with a strong coupling between the magnetization and the polarization
+fields may be achieved in this family since these magnetic insulators can
+present structural self-ordering in the appropriate growth conditions. We have
+studied the functional properties of La2CoMnO6 and Bi2CoMnO6 epitaxial thin
+films grown by pulsed laser deposition. Cation-ordered La2CoMnO6 films display
+a magnetic Curie temperature of 250 K while cation-disordered Bi2CoMnO6 films
+present ferromagnetism up to ~ 800 K. Such high transition temperature for
+magnetic ordering can be further tuned by varying the strain in the films
+indicating an important contribution from the structural characteristics of the
+materials. Our approach might be generalized for other oxide systems. At this
+end, our results are compared with other multiferroic systems. The roles of
+various cations, their arrangements and structural effects are further
+discussed.",0904.0615v1
+2010-06-29,Magnetic properties of exchange biased and of unbiased oxide/permalloy thin layers: a ferromagnetic resonance and Brillouin scattering study,"Microstrip ferromagnetic resonance and Brillouin scattering are used to
+provide a comparative determination of the magnetic parameters of thin
+permalloy layers interfaced with a non-magnetic (Al2O3) or with an
+antiferromagnetic oxide (NiO). It is shown that the perpendicular anisotropy is
+monitored by an interfacial surface energy term which is practically
+independent of the nature of the interface. In the investigated interval of
+thicknesses (5-25 nm) the saturation magnetisation does not significantly
+differ from the reported one in bulk permalloy. In-plane uniaxial anisotropy
+and exchange-bias anisotropy are also derived from this study of the dynamic
+magnetic excitations and compared to our independent evaluations using
+conventional magnetometry",1006.5598v1
+2010-07-19,High-Tc ferrolectricity emerging from magnetic degeneracy in cupric oxide,"Cupric oxide is multiferroic at unusual high temperatures. From density
+functional calculations we find that the low-T magnetic phase is paraelectric
+and the higher-T one ferroelectric, with a size and direction of polarization
+in good agreement with experiment. By mapping of the ab initio results on an
+effective spin model we find with Monte Carlo that in the high-T magnetic state
+non-collinearity and inversion symmetry breaking stabilize each other via the
+Dzyaloshinskii Moriya interaction. This leads to a novel mechanism for
+multiferroicity, with the particular property that non-magnetic impurities
+enhance the effect.",1007.3220v2
+2010-09-20,Sr$_6$Co$_5$0{$_1$$_5$}: non-one-dimensional behavior of a charge ordered structurally quasi-one-dimensional oxide,"We have synthesized Sr$_6$Co$_5$O$_{15}$, a quasi-one-dimensional oxide,
+measured its magnetic properties and calculated its electronic structure by ab
+initio techniques. We have found strong evidence for its electronic and
+magnetic behavior not to follow the trend of its structural series. The
+magnetic coupling inside the CoO$_3$ chains is not purely ferromagnetic, the
+long-range coupling inside them is very weak. The Co moments are slightly
+canted due to their large orbital angular momenta being oriented along each
+particular quantization axis, that is different for each Co$^{4+}$ atom in the
+structure. Our thermopower calculations are in agreement with the experiment,
+supporting our model of the magnetic ground state of the compound.",1009.3736v2
+2010-10-05,Structural and magnetic characterization of self-assembled iron oxide nanoparticle arrays,"We report about a combined structural and magnetometric characterization of
+self-assembled magnetic nanoparticle arrays. Monodisperse iron oxide
+nanoparticles with a diameter of 20 nm were synthesized by thermal
+decomposition. The nanoparticle suspension was spin-coated on Si substrates to
+achieve self-organized arrays of particles and subsequently annealed at various
+conditions. The samples were characterized by x-ray diffraction, bright and
+dark field high resolution transmission electron microscopy (HRTEM). The
+structural analysis is compared to the magnetic behavior investigated by
+superconducting interference device (SQUID) magnetometry. We can identify
+either multi-phase FeO/g-Fe2O3 or multi-phase FeO/Fe3O4 nanoparticles. The
+FeO/g-Fe2O3 system shows a pronounced exchange bias effect which explains the
+peculiar magnetization data obtained for this system.",1010.0938v1
+2011-01-10,Novel magnetic order in pseudogap state of high Tc copper oxides superconductors,"One of the leading issues in high-$\rm T_c$ copper oxide superconductors is
+the origin of the pseudogap phase in the underdoped regime of their phase
+diagram. Using polarized neutron diffraction, a novel magnetic order has been
+identified as an hidden order parameter of the pseudogap as the transition
+temperature corresponds to what is expected for the pseudogap. The observed
+magnetic order preserves translational symmetry as predicted for orbital
+moments in the circulating current theory. Being now reported in three
+different cuprates familles, it appears as a universal phenomenon whatever the
+crystal structure (with single CuO$_2$ layer or bilayer per unit cell). To
+date, it is the first direct evidence of an hidden order parameter
+characterizing the pseudogap phase of high-$\rm T_c$ cuprates.",1101.1786v2
+2011-06-14,Crossover between two different magnetization reversal modes in arrays of iron oxide nanotubes,"The magnetization reversal in ordered arrays of iron oxide nanotubes of 50 nm
+outer diameter grown by atomic layer deposition is investigated theoretically
+as a function of the tube wall thickness, $d_{w}$. In thin tubes ($d_{w}<13$
+nm) the reversal of magnetization is achieved by the propagation of a vortex
+domain boundary, while in thick tubes ($d_{w}>13$ nm) the reversal is driven by
+the propagation of a transverse domain boundary. Magnetostatic interactions
+between the tubes are responsible for a decrease of the coercive field in the
+array. Our calculations are in agreement with recently reported experimental
+results. We predict that the crossover between the vortex and transverse modes
+of magnetization reversal is a general phenomenon on the length scale
+considered.",1106.2833v1
+2011-08-25,Fabrication of magnetic clusters and rods using electrostatic co-assembly,"Using a novel protocol for mixing oppositely charged colloids and
+macromolecules, magnetic clusters and rods are fabricated using 10 nm-iron
+oxide nanoparticles and polymers. Here, we show that as the dispersions undergo
+the so-called desalting transition, spherical clusters in the range 100 nm - 1
+{\mu}m form spontaneously upon dialysis or dilution. With a magnetic field
+applied during the dialysis, a one-dimensional growth of the aggregates is
+initiated, resulting in the formation of 1 - 100 {\mu}m rods of average
+diameter 200 nm. In this paper, we demonstrate that the nanostructured rods
+have inherited the properties of the iron oxide particles, namely to be
+superparamagnetic. We also discuss the dependence of the magnetic properties as
+a function of the nanoparticle diameter.",1108.5023v1
+2011-10-10,Magnetic order and frustrated dynamics in Li(Ni0.8Co0.1Mn0.1)O2: a study by μ+SR and SQUID magnetometry,"Recently, the mixed transition metal oxides of the form Li(Ni1-y-zCoyMnz)O2,
+have become the center of attention as promising candidates for novel battery
+material. These materials have also revealed very interesting magnetic
+properties due to the alternate stacking of planes of metal oxides on a 2D
+triangular lattice and the Li-layers. The title compound,
+Li(Ni0.8Co0.1Mn0.1)O2, has been investigated by both magnetometry and
+measurements and {\mu}+SR. We find the evolution of localized magnetic moments
+with decreasing temperature below 70 K. The magnetic ground state (T = 2 K) is,
+however, shown to be a frustrated system in 3D, followed by a transition into a
+possible 2D spinglass above 22 K. With further increasing temperature the
+compound show the presence of remaining correlations with increasing effective
+dimensionality all the way up to the ferrimagnetic transition at TC = 70 K.",1110.2071v1
+2015-07-07,Spectrum for non-magnetic Mott insulators from power functional within Reduced Density Matrix Functional Theory,"A fully first principles theory capable of treating strongly correlated
+solids remains the outstanding challenge of modern day materials science. This
+is exemplified by the transition metal oxides, prototypical Mott insulators,
+that remain insulating even in the absence of long range magnetic order.
+Capturing the non-magnetic insulating state of these materials presents a
+difficult challenge for any modern electronic structure theory. In this paper
+we demonstrate that reduced density matrix functional theory, in conjunction
+with the power functional, can successfully treat the non-magnetic insulating
+state of the transition metal oxides NiO and MnO. We show that the electronic
+spectrum retains a gap even in the absence of spin order. We further discuss
+the detailed way in which RDMFT performs for Mott insulators and band
+insulators, finding that for the latter occupation number minimization alone is
+required, but for the former full minimization over both occupation numbers and
+natural orbitals is essential.",1507.01754v1
+2015-08-14,Antiferromagnetism at T > 500 K in the Layered Hexagonal Ruthenate SrRu2O6,"We report an experimental and computational study of magnetic and electronic
+properties of the layered Ru(V) oxide SrRu2O6 (hexagonal, P-3 1m), which shows
+antiferromagnetic order with a N\'eel temperature of 563(2) K, among the
+highest for 4d oxides. Magnetic order occurs both within edge-shared octahedral
+sheets and between layers and is accompanied by anisotropic thermal expansivity
+that implies strong magnetoelastic coupling of Ru(V) centers. Electrical
+transport measurements using focused ion beam induced deposited contacts on a
+micron-scale crystallite as a function of temperature show p-type
+semiconductivity. The calculated electronic structure using hybrid density
+functional theory successfully accounts for the experimentally observed
+magnetic and electronic structure and Monte Carlo simulations reveals how
+strong intralayer as well as weaker interlayer interactions are a defining
+feature of the high temperature magnetic order in the material.",1508.03609v2
+2015-11-09,Mechanism responsible for initiating room temperature ferromagnetism and spin polarized current in diluted magnetic oxides,"The main obstacles in realizing diluted magnetic oxide (DMO) in spintronics
+are the unknown electronic structures associated with its high TC
+ferromagnetism and spin polarized current and how to manipulate desired
+electronic structures by fabrication techniques. We demonstrate that fine-tuned
+electronic structures and band structures can be modified to initiate DMO
+properties. Interestingly, in the semiconducting state, the doped Co ions and
+oxygen vacancies contribute non-negligible magnetic moments; and the magnetic
+coupling between these moments is mediated by the localized carriers via highly
+spin polarized hopping transport. These results unravel the myth of the origin
+of spintronic characteristics with desirable electronic states; thereby
+reopening the door for future applications.",1511.02632v1
+2015-11-26,Strong magnetic frustration and anti-site disorder causing spin-glass behavior in honeycomb Li2RhO3,"With large spin-orbit coupling, the $t_{2g}^5$ electron configuration in
+$d$-metal oxides is prone to highly anisotropic exchange interactions and
+exotic magnetic properties. In $5d^5$ iridates, given the existing variety of
+crystal structures, the magnetic anisotropy can be tuned from antisymmetric to
+symmetric Kitaev-type, with interaction strengths that outsize the isotropic
+terms. By many-body electronic-structure calculations we here address the
+nature of the magnetic exchange and the intriguing spin-glass behavior of
+Li$_2$RhO$_3$, a $4d^5$ honeycomb oxide. For pristine crystals without Rh-Li
+site inversion, we predict a dimerized ground state as in the isostructural
+$5d^5$ iridate Li$_2$IrO$_3$, with triplet spin dimers effectively placed on a
+frustrated triangular lattice. With Rh-Li anti-site disorder, we explain the
+observed spin-glass phase as a superposition of different, nearly degenerate
+symmetry-broken configurations.",1511.08333v1
+2016-10-03,Orbital driven impurity spin effect on the magnetic order of quasi-three dimensional cupric oxide,"Density functional calculations are performed to study the magnetic order of
+the severely distorted square planar cupric oxide (CuO) and local spin disorder
+in it in the presence of the transition metal impurities M (= Cr, Mn, Fe, Co
+and Ni). The distortion in the crystal structure, arisen to reduce the band
+energy by minimizing the covalent interaction, creates two crisscrossing zigzag
+spin-1/2 chains. From the spin dimer analysis we find that while the spin chain
+along [10$\bar 1$] has strong Heisenberg type antiferromagnetic coupling (J ~
+127 meV), along [101] it exhibits weak, but robust, ferromagnetic coupling (J ~
+9 meV) mediated by reminiscent p-d covalent interactions. The impurity effect
+on the magnetic ordering is independent of M and purely orbital driven. If the
+given spin-state of M is such that the d$_{x^2-y^2}$ orbital is spin-polarized,
+then the original long-range ordering is maintained. However, if d$_{x^2-y^2}$
+orbital is unoccupied, the absence of corresponding covalent interaction breaks
+the weak ferromagnetic coupling and a spin-flip takes place at the impurity
+site leading to breakdown of the long range magnetic ordering.",1610.00458v1
+2011-11-28,Noncollinear magnetism and spin-orbit coupling in 5d pyrochlore oxide Cd2Os2O7,"We investigated the electronic and magnetic properties of the pyrochlore
+oxide Cd$_2$Os$_2$O$_7$ using the density-functional theory plus on-site
+repulsion ($U$) method, and depict the ground-state phase diagram with respect
+to $U$. We conclude that the all-in/all-out non-collinear magnetic order is
+stable in a wide range of $U$. We also show that the easy-axis anisotropy
+arising from the spin-orbit (SO) coupling plays a significant role in
+stabilizing the all-in/all-out magnetic order. A \textit{pseudo gap} was
+observed near the transition between the antiferromagnetic metallic and
+insulating phases. Finally, we discuss possible origins of the peculiar
+low-temperature($T$) properties observed in experiments.",1111.6347v2
+2018-09-04,Formation and Control of Twin Domains in the Pyrochlore Oxide Cd2Re2O7,"The successive phase transitions of the pyrochlore oxide Cd2Re2O7 are studied
+by polarizing microscopy and magnetic susceptibility measurements. The
+formation of twin domains is visualized in the polarizing images of a pristine
+(111) crystal surface upon cooling through the cubic-to-tetragonal transition
+at Ts1 ~ 200 K. Moreover, a dramatic change in the twinning pattern is observed
+at Ts2 ~120 K, which suggests that the tetragonal c axis flips as the strain
+changes its direction at the tetragonal-to-tetragonal transition. Magnetic
+susceptibility measurements reveal significant domain alignment upon cooling
+across Ts1 and Ts2 in a magnetic field of 7 T, which are due to ~10% anisotropy
+in the magnetic susceptibility for the low-temperature phases. Interestingly,
+the anisotropy is reversed at Ts2: \c{hi}c < \c{hi}a above Ts2 and vice versa
+below Ts2.",1809.00771v2
+2018-10-10,Spin-Orbital Entangled Liquid State in the Copper Oxide Ba$_3$CuSb$_2$O$_9$,"Structure with orbital degeneracy is unstable toward spontaneous distortion.
+Such orbital correlation usually has a much higher energy scale than spins, and
+therefore, magnetic transition takes place at a much lower temperature, almost
+independently from orbital ordering. However, when the energy scales of
+orbitals and spins meet, there is a possibility of spin-orbital entanglement
+that would stabilize novel ground state such as spin-orbital liquid and random
+singlet state. Here we review on such a novel spin-orbital magnetism found in
+the hexagonal perovskite oxide Ba$_3$CuSb$_2$O$_9$, which hosts a
+self-organized honeycomblike short-range order of a strong Jahn-Teller ion
+Cu$^{2+}$. Comprehensive structural and magnetic measurements have revealed
+that the system has neither magnetic nor Jahn-Teller transition down to the
+lowest temperatures, and Cu spins and orbitals retain the hexagonal symmetry
+and paramagnetic state. Various macroscopic and microscopic measurements all
+indicate that spins and orbitals remain fluctuating down to low temperatures
+without freezing, forming a spin-orbital entangled liquid state.",1810.04346v1
+2019-07-23,Magnetotransport properties of granular oxide-segregated CoPtCr films for applications in future magnetic memory technology,"Magnetotransport properties of granular oxide-segregated CoPtCr films were
+studied on both macroscopic and microscopic length scales by performing bulk
+and point-contact magnetoresistance measurements, respectively. Such a
+perpendicular magnetic medium is used in state-of-the-art hard disc drives and
+if combined with magnetoresistive phenomena (for read/write operations) may
+lead to a novel concept for magnetic recording with high areal density. While
+the bulk measurements on the films showed only small variations in dc
+resistance as a function of applied magnetic field (magnetoresistance of less
+than 0.02 %), the point-contact measurements revealed
+giant-magnetoresistance-like changes in resistance with up to 50,000 % ratios.
+The observed magnetorestive effect could be attributed to a tunnel
+magnetoresistance between CoPtCr grains with different coercivity. The
+tunneling picture of electronic transport in our granular medium was confirmed
+by the observation of tunneling-like current-voltage characteristics and bias
+dependence of magnetoresistance; both the point-contact resistance and
+magnetoresistance were found to decrease with the applied dc bias.",1907.09675v1
+2020-01-09,"High temperature thermal cycling effect on the irreversible responses of lattice structure, magnetic properties and electrical conductivity in Co$_{2.75}$Fe$_{0.25}$O$_{4+δ}$ spinel oxide","We report high temperature synchrotron X-ray diffraction (SXRD), dc
+magnetization and current-voltage (I-V) characteristics for the samples of
+Co$_{2.75}$Fe$_{0.25}$O$_4$ ferrite. The material was prepared by chemical
+reaction of the Fe and Co nitrate solutions at pH = 11 and subsequent annealing
+at temperatures 200 0C, 500 0C and 900 0C. The measurements were performed by
+cycling the temperature from 300 K to high temperature (warming mode) and
+return back to 300 K (cooling mode). The SXRD patterns indicated a fine
+bi-phased cubic spinel structure in the highly Co rich spinel oxide.
+Magnetization curves showed intrinsic ferrimagnetic features and defect induced
+additional ferromagnetic phase at higher temperatures. Electrical conductivity
+showed thermal hysteresis loop between warming and cooling modes of temperature
+variation. The samples exhibited new information on the irreversibility
+phenomena of lattice structure, magnetization and electrical conductivity on
+cycling the measurement temperatures.",2001.02829v2
+2021-07-11,Hysteretic Magnetoresistance in a Non-Magnetic SrSnO3 Film via Thermal Coupling to Dynamic Substrate Behavior,"Hysteretic magnetoresistance (MR) is often used as a signature of
+ferromagnetism in conducting oxide thin films and heterostructures. Here,
+magnetotransport is investigated in a non-magnetic uniformly La-doped SrSnO3
+film grown using hybrid molecular beam epitaxy. A 12 nm La:SrSnO3/2 nm
+SrSnO3/GdScO3 (110) film with insulating behavior exhibited a robust hysteresis
+loop in the MR at T < 5 K accompanied by an anomaly at ~ +/- 3 T at T < 2.5 K.
+Furthermore, MR with the field in-plane yielded a value exceeded 100% at 1.8 K.
+Using detailed temperature-, angle- and magnetic field-dependent resistance
+measurements, we illustrate the origin of hysteresis is not due to magnetism in
+the film but rather is associated with the magnetocaloric effect of the GdScO3
+substrate. Given GdScO3 and similar substrates are commonly used in complex
+oxide research, this work highlights the importance of thermal coupling to
+processes in the substrates which must be carefully accounted for in the data
+interpretation for thin films and heterostructures utilizing these substrates.",2107.04965v1
+2022-05-02,Novel quantum phase of the chromium spinel oxide HgCr$_{\rm 2}$O$_{\rm 4}$ in high magnetic fields,"In this study, we have performed the magnetocaloric effect and the specific
+heat measurements of chromium spinel oxide HgCr$_2$O$_4$, wherein the magnetic
+Cr$^{3+}$ ions form a highly frustrated pyrochlore lattice with significant
+spin-lattice coupling. In addition to the known magnetic-field-induced phases,
+our thermodynamic measurements detect a novel quantum phase just before the
+saturation of the magnetization, which has not been expected from the classical
+theories of the pyrochlore lattice antiferromagnet with spin-lattice coupling.
+Based on recent theoretical model calculation, we discuss the possibility of a
+spin nematic state appearing for this quantum phase.",2205.00810v1
+2023-03-20,Electronic and magnetic properties of Lu and LuH$_2$,"Clarifying the electronic and magnetic properties of lutetium, lutetium
+dihydride, and lutetium oxide is very helpful to understand the emergent
+phenomena in lutetium-based compounds (such as room-temperature
+superconductivity). However, this kind of study is still scarce at present.
+Here, we report on the electronic and magnetic properties of lutetium metals,
+lutetium dihydride powders, and lutetium oxide powders. Crystal structures and
+chemical compositions of these samples were characterized by X-ray diffraction
+and X-ray photoemission spectroscopy, respectively. Electrical transport
+measurements show that the resistance of lutetium has a linear behavior
+depending on temperature, whereas the resistance of lutetium dihydride powders
+is independent of temperature. More interestingly,
+paramagnetism-ferromagnetism-spin glass transitions were observed at near 240
+and 200 K, respectively, in lutetium metals. Our work uncovered the complex
+magnetic properties of Lu-based compounds.",2303.11063v2
+2023-07-18,Room-temperature magnetism and controlled cation distribution in vanadium ferrite thin films,"Spinel oxides demonstrate significant technological promise due to the vast
+array of interrelated physical properties that their unique structure supports.
+Specifically, the Fe1+xV2-xO4 spinel system garners extensive interest due to
+the presence of orbitally ordered states and multiferroism. This study focuses
+on the elaboration of high-quality Fe2VO4 (x = 1) thin films on MgO substrates
+via pulsed laser deposition. Structural analyses confirm the epitaxial growth
+of the films, their high crystallinity and fully strained nature. The cationic
+distribution and stoichiometry were investigated using Resonant Elastic X-ray
+Scattering experiments, in conjunction with comprehensive characterization of
+the films' physical and electrical properties. The films exhibit
+room-temperature magnetism, with a magnetization consistent with the
+(Fe3+)Td[Fe2+V3+2]OhO4 inverse spinel structure unveiled by anomalous
+diffraction. This work represents the inaugural successful deposition of Fe2VO4
+thin films, thereby expanding the family of spinel vanadium oxide thin films
+with a new member that demonstrates room-temperature magnetic properties.",2307.09598v1
+2004-03-29,Quantum Tunneling of the Magnetization in the Ising Chain Compound Ca3Co2O6,"The magnetic behavior of the Ca3Co2O6 spin chain compound is characterized by
+a large Ising-like character of its ferromagnetic chains, set on triangular
+lattice, that are antiferromagnetically coupled. At low temperature, T < 7K,
+the 3D antiferromagnetic state evolves towards a spin frozen state. In this
+temperature range, magnetic field driven magnetization of single crystals
+(H//chains) exhibits stepped variations. The occurrence of these steps at
+regular intervals of the applied magnetic field, Hstep=1.2T, is reminiscent of
+the quantum tunneling of the magnetization (QTM) of molecular based magnets.
+Magnetization relaxation experiments also strongly support the occurrence of
+this quantum phenomenon. This first observation of QTM in a magnetic oxide
+belonging to the large family of the A3BBO6 compounds opens new opportunities
+to study a quantum effect in a very different class of materials from molecular
+magnets.",0403695v1
+2018-11-09,Giant Exchange Bias in the Single-layered Ruddlesden-Popper Perovskite SrLaCo0.5Mn0.5O4,"Exchange bias (EB) as large as ~5.5 kOe is observed in SrLaCo0.5Mn0.5O4 which
+is the highest ever found in any layered transition metal oxides including
+Ruddlesden-Popper series. Neutron diffraction measurement rules out long-range
+magnetic ordering and together with dc magnetic measurements suggest formation
+of short-range magnetic domains. AC magnetic susceptibility, magnetic memory
+effect and magnetic training effect confirm the system to be a cluster spin
+glass. By carrying out density functional calculations on several model
+configurations, we propose that EB is originated at the boundary between
+Mn-rich antiferromagnetic and Co-rich ferromagnetic domains at the
+sub-nanoscale. Reversal of magnetization axis on the Co-side alters the
+magnetic coupling between the interfacial Mn and Co spins which leads to EB.
+Our analysis infers that the presence of competing magnetic interactions is
+sufficient to induce exchange bias and thereby a wide range of materials
+exhibiting giant EB can be engineered for designing novel magnetic memory
+devices.",1811.03960v1
+2017-12-05,Inducing and Manipulating Magnetization in Two-Dimensional ZnO by Strain and External Gating,"Two-dimensional structures that exhibit intriguing magnetic phenomena such as
+perpendicular magnetic anisotropy and switchable magnetization are of great
+interests in spintronics research. Herein, the density-functional theory
+studies reveal the critical impacts of strain and external gating on
+vacancy-induced magnetism and its spin direction in a graphene-like single
+layer of zinc oxide (ZnO). In contrast to the pristine and defective ZnO with
+an O-vacancy, the presence of a Zn-vacancy induces significant magnetic moments
+to its first neighboring O and Zn atoms due to the charge deficit. We further
+predict that the direction of magnetization easy axis reverses from an in-plane
+to perpendicular orientation under a practically achieved biaxial compressive
+strain of $\sim$1--2\% or applying an electric-field by means of the charge
+density modulation. This magnetization reversal is driven by the strain- and
+electric-field-induced changes in the spin-orbit coupled \emph{d} states of the
+first-neighbor Zn atom to the Zn-vacancy. These findings open interesting
+prospects for exploiting strain and electric-field engineering to manipulate
+magnetism and magnetization orientation of two-dimensional materials.",1712.01578v1
+2019-03-01,A quantum pathway to overcome the trilemma of magnetic data storage,"The three essential pillars of magnetic data storage devices are readability,
+writeability, and stability. However, these requirements compete as magnetic
+domain sizes reach the fundamental limit of single atoms and molecules. The
+proven magnetic bistability of individual holmium atoms on magnesium oxide
+appeared to operate within this magnetic trilemma, sacrificing writeability for
+unprecedented stability. Using the magnetic stray field created by the tip of a
+spin-polarized scanning tunneling microscope (SP-STM), we controllably move the
+Ho state into the quantum regime, allowing us to write its state via the
+quantum tunneling of magnetization (QTM). We find that the hyperfine
+interaction causes both the excellent magnetic bistability, even at zero
+applied magnetic field, and the avoided level crossings which we use to control
+the magnetic state via QTM. We explore how to use such a system to realize a
+high-fidelity single atom NOT gate (inverter). Our approach reveals the
+prospect of combining the best traits of the classical and quantum worlds for
+next generation data storage.",1903.00242v1
+2023-06-11,Jahn-Teller magnets,"A wide class of materials with different crystal and electronic structures
+from quasi-two-dimensional unconventional superconductors (cuprates,
+nickelates, ferropnictides/chalcogenides, ruthenate SrRuO$_4$), 3D systems as
+manganites RMnO$_3$, ferrates (CaSr)FeO$_3$, nickelates RNiO$_3$, to silver
+oxide AgO are based on Jahn-Teller $3d$ and $4d$ ions. These unusual materials
+called Jahn-Teller (JT) magnets are characterized by an extremely rich variety
+of phase states from non-magnetic and magnetic insulators to unusual metallic
+and superconducting states. The unconventional properties of the JT-magnets can
+be related to the instability of their highly symmetric Jahn-Teller
+""progenitors"" with the ground orbital $E$-state to charge transfer with
+anti-Jahn-Teller $d$-$d$ disproportionation and the formation of a system of
+effective local composite spin-singlet or spin-triplet, electronic or hole
+$S$-type bosons moving in a non-magnetic or magnetic lattice. We consider
+specific features of the anti-JT-disproportionation reaction, properties of the
+electron-hole dimers, possible phase states of JT-magnets, effective
+Hamiltonians for single- and two-band JT-magnets, and present a short overview
+of physical properties for actual JT-magnets.",2306.06612v1
+2010-01-06,Proximity effect and electron transport in the oxide hybrid heterostructures with superconducting/magnetic interfaces,"We report on the study of electron transport in the oxide heterostructures
+with superconductor/magnetic matter (S/M) interfaces where anomaly large
+penetration of superconducting correlations in magnetic matter (proximity
+effect) is realized. The developed theoretical model based on multilayer
+magnetic structure of M-interlayer and experiment show presence of the
+long-range proximity effect at S/M-interface with antiferromagnetic (AF)
+ordering of the interlayer magnetization. The investigated hybrid
+heterostructures include cuprate superconductor, the AF-cuprate interlayer and
+conventional superconductor, Nb. The superconducting critical current with
+density 1-10A/cm2 and the characteristic voltage, 0.1-0.2 mV, are observed at
+liquid helium temperature for 15-50 nm thick M-interlayer made of AF film
+CaSrCuO. These heterostructures demonstrate deviation from sin-type
+superconducting current-phase relation and had the critical current of the
+second harmonic of 10-20% of the first harmonic one. The hybrid
+heterostructures with S/AF interface show high sensitivity to the external
+magnetic field that is possibly caused by the influence of an external magnetic
+field on the canting of magnetic moments of individual layers of AF
+-interlayer. Substituting the AF cuprate by a manganite film, no critical
+current was observed, although the M- interlayer was made very thin, down to 5
+nm.",1001.0963v1
+2018-11-24,The interfacial spin modulation of graphene on Fe(111),"When Fe, which is a typical ferromagnet using d- or f-orbital states, is
+combined with 2D materials such as graphene, it offers many opportunities for
+spintronics. The origin of 2D magnetism is from magnetic insulating behaviors,
+which could result in magnetic excitations and also proximity effects. However,
+the phenomena were only observed at extremely low temperatures. Fe and graphene
+interfaces could control spin structures in which they show a unique atomic
+spin modulation and magnetic coupling through the interface. Another reason for
+covering graphene on Fe is to prevent oxidation under ambient conditions. We
+investigated the engineering of spin configurations by growing monolayer
+graphene on an Fe(111) single crystal surface and observed the presence of
+sharply branched, 3D tree-like domain structures. Magnetization by a sweeping
+magnetic field (m-H) revealed that the interface showed canted magnetization in
+the in-plane (IP) orientation. Moreover, graphene could completely prevent the
+oxidation of the Fe surface. The results indicate possible control of the spin
+structures at the atomic scale and the interface phenomena in the 2D structure.
+The study introduces a new approach for room temperature 2D magnetism.",1811.09773v1
+2018-10-09,"Magnetic behavior, Griffiths phase and magneto-transport study in 3$d$ based nano-crystalline double perovskite Pr$_2$CoMnO$_6$","Double perovskite (DP) oxide material receive extensive research interest due
+to exciting physical properties with potential technological application. 3$d$
+based DP oxides are promising for exciting physics like magnetodielectric,
+ferroelectric, Griffith phase etc., specially Co/Mn DPs are gaining much
+research interest. In this paper we present the study of magnetic phase and
+transport properties in nano-crystalline Pr$_2$CoMnO$_6$ a 3$d$ based double
+perovskite compound. This material shows a paramagnetic (PM) to ferromagnetic
+(FM) phase transition below 173 K marked by a rapid increase in magnetic moment
+due to spin ordering. We found divergence in inverse magnetic susceptibility
+($\chi$$^{-1}$) from Curie weiss behavior around 206 K which indicates the
+evolution of Griffiths phase before actual PM-FM transition. We found that the
+Griffiths phase suppressed with increasing applied magnetic filed. For the
+understanding of charge transport in this material we have measured temperature
+dependent electrical resistivity. Pr$_2$CoMnO$_6$ is a strong insulator where
+resistivity increase abruptly below magnetic phase transition. To understand
+the effect of magnetic field on transport behavior we have also measured the
+magnetoresistance (MR) at different temperatures. Sample shows the negative MR
+with maximum value $\sim$22 $\%$ under applied magnetic field of 50 kOe at 125
+K. MR follows quadratic field dependency above $T_c$ however below $T_c$ the MR
+shows deviation from this field dependency at low field.",1810.03895v1
+2019-02-14,High-speed domain wall racetracks in a magnetic insulator,"Recent reports of current-induced switching of ferrimagnetic oxides coupled
+to a heavy metal layer have opened realistic prospects for implementing
+magnetic insulators into electrically addressable spintronic devices. However,
+key aspects such as the configuration and dynamics of magnetic domain walls
+driven by electrical currents in insulating oxides remain unexplored. Here, we
+investigate the internal structure of the domain walls in Tm3Fe5O12 (TmIG) and
+TmIG/Pt bilayers and demonstrate their efficient manipulation by spin-orbit
+torques with velocities of up to 400 m s$^{-1}$ and minimal current threshold
+for domain wall flow of 5 x 10$^{6}$ A cm$^{-2}$. Domain wall racetracks
+embedded in TmIG are defined by the deposition of Pt current lines, which allow
+us to control the domain propagation and magnetization switching in selected
+regions of an extended magnetic layer. Scanning nitrogen-vacancy magnetometry
+reveals that the domain walls of thin TmIG films are N\'eel walls with
+left-handed chirality, with the domain wall magnetization rotating towards an
+intermediate N\'eel-Bloch configuration upon deposition of Pt. These results
+indicate the presence of a sizable interfacial Dzyaloshinskii-Moriya
+interaction in TmIG, which leads to novel possibilities to control the
+formation of chiral spin textures in magnetic insulators. Ultimately, domain
+wall racetracks provide an efficient scheme to pattern the magnetic landscape
+of TmIG in a fast and reversible way",1902.05639v1
+2022-10-18,Spin re-orientation induced anisotropic magnetoresistance switching in LaCo$_{0.5}$Ni$_{0.5}$O$_{3-δ}$ thin films,"Realization of novel functionalities by tuning magnetic interactions in rare
+earth perovskite oxide thin films opens up exciting technological prospects.
+Strain-induced tuning of magnetic interactions in rare earth cobaltates and
+nickelates is of central importance due to their versatility in electronic
+transport properties. Here we reported the spin re-orientation induced
+switching of anisotropic magnetoresistance (AMR) and its tunability with strain
+in epitaxial LaCo$_{0.5}$Ni$_{0.5}$O$_{3-\delta}$ thin films across the
+ferromagnetic transition. Moreover, with strain tuning, we could observe a
+two-fold to four-fold symmetry crossover in AMR across the magnetic transition
+temperature. The magnetization measurements revealed an onset of ferromagnetic
+transition around 50 K, and a further reduction in temperature showed a subtle
+change in the magnetization dynamics, which reduced the ferromagnetic
+long-range ordering and introduced glassiness in the system. X-ray absorption
+and X-ray magnetic circular dichroism spectroscopy measurements over Co and Ni
+L edges revealed the Co spin state transition below the magnetic transition
+temperature leading to the AMR switching and also the presence of Ni$^{2+}$ and
+Co$^{4+}$ ions evidencing the charge transfer from Ni to Co ions. Our work
+demonstrated the tunability of magnetic interactions mediated electronic
+transport in cobaltate-nickelate thin films, which is relevant in understanding
+Ni-Co interactions in oxides for their technological applications such as in
+AMR sensors.",2210.09608v3
+2021-10-21,Heat Capacity of oxide scale in the range from 0 C to 1300 C: Generalized estimates with account for movability of phase transitions,"The known data on the heat capacity of magnetite (Fe3O4), hematite (Fe2O3)
+and iron (Fe) at different temperatures are approximated by formulas containing
+phase transition temperatures as varying parameters. This allows to take into
+account the effect of phase transition shifts, for example, due to impurities,
+lattice defects, grain sizes or high cooling rates. For this purpose, the
+entire target temperature range from 0 C to 1300 C is divided by phase
+transition temperatures into separate intervals. The conjugation of the
+approximating functions between the intervals at the magnetic transition point
+is performed without a gap, and at the point of polymorphic transformation
+(alpha Fe - gamma Fe) with a finite gap of heat capacity values. For wustite
+Fe1-xO which does not experience phase transformations, the temperature
+dependence of the heat capacity is approximated by a single smooth function. In
+combination with previously obtained formulas for the density of iron oxides
+and iron the proposed approximations allow us to estimate the specific mass
+heat capacity of oxide scale depending of its structural composition and
+temperature. By model calculations it is shown that at temperatures of 200 C
+and 900 C specific mass heat capacity of oxide scale practically does not
+depend on the percentage of its individual components and is approximately 750
+and 850 J/(kg K) respectively. At a temperature of about 575 C, on contrary,
+actually possible variations in the composition of oxide scale can lead to a
+change in its specific heat capacity from 850 to 1150 J/(kg K). The obtained
+dependencies are recommended for use in mathematical modeling of production and
+processing of steel products in the presence of oxide scale on their surface",2110.11101v1
+2011-01-04,"Density functional theory analysis of the interplay between Jahn-Teller instability, uniaxial magnetism, spin arrangement, metal-metal interaction and spin-orbit coupling in Ca3CoMO6 (M = Co, Rh, Ir)","In the isostructural oxides Ca3CoMO6 (M = Co, Rh, Ir), the CoMO6 chains made
+up of face-sharing CoO6 trigonal prisms and MO6 octahedra are separated by Ca
+atoms. We analyzed the magnetic and electronic properties of these oxides on
+the basis of density functional theory calculations including on-site repulsion
+and spin-orbit coupling, and examined the essential one-electron pictures
+hidden behind results of these calculations. Our analysis reveals an intimate
+interplay between Jahn-Teller instability, uniaxial magnetism, spin
+arrangement, metal-metal interaction, and spin-orbit coupling in governing the
+magnetic and electronic properties of these oxides. These oxides undergo a
+Jahn-Teller distortion but their distortions are weak, so that their
+trigonal-prism Con+ (n = 2, 3) ions still give rise to strong easy-axis
+anisotropy along the chain direction. As for the d-state split pattern of these
+ions, the electronic and magnetic properties of Ca3CoMO6 (M = Co, Rh, Ir) are
+consistent with d0 < (d2, d-2) < (d1, d-1), but not with (d2, d-2) < d0 < (d1,
+d-1). The trigonal-prism Co3+ ion in Ca3Co2O6 has the L = 2 configuration
+(d0)1(d2, d-2)3(d1, d-1)2 because of the metal-metal interaction between
+adjacent Co3+ ions in each Co2O6 chain, which is mediated by their z2 orbitals,
+and the spin-orbit coupling of the trigonal-prism Co3+ ion. The spins in each
+CoMO6 chain of Ca3CoMO6 prefer the ferromagnetic arrangement for M = Co and Rh,
+but the antiferromagnetic arrangement for M = Ir. The octahedral M4+ ion of
+Ca3CoMO6 has the (1a)1(1e)4 configuration for M = Rh but the (1a)2(1e)3
+configuration for M = Ir, which arises from the difference in the spin-orbit
+coupling of the M4+ ions and the Co...M metal-metal interactions.",1101.0644v1
+2019-07-26,Stabilization of $\varepsilon$-Fe$_2$O$_3$ epitaxial layer on MgO(111)/GaN via an intermediate $γ$-Fe$_2$O$_3$-phase,"In the present study we have demonstrated epitaxial stabilization of the
+metastable magnetically-hard $\varepsilon$-Fe$_2$O$_3$ phase on top of a thin
+MgO(111) buffer layer grown onto the GaN (0001) surface. The primary purpose to
+introduce a 4\,nm-thick buffer layer of MgO in between Fe$_2$O$_3$ and GaN was
+to stop thermal migration of Ga into the iron oxide layer. Though such
+migration and successive formation of the orthorhombic GaFeO$_3$ was supposed
+earlier to be a potential trigger of the nucleation of the isostructural
+$\varepsilon$-Fe$_2$O$_3$, the present work demonstrates that the growth of
+single crystalline uniform films of epsilon ferrite by pulsed laser deposition
+is possible even on the MgO capped GaN. The structural properties of the 60\,nm
+thick Fe$_2$O$_3$ layer on MgO / GaN were probed by electron and x-ray
+diffraction, both suggesting that the growth of $\varepsilon$-Fe$_2$O$_3$ is
+preceded by formation of a thin layer of $\gamma$-Fe$_2$O$_3$. The presence of
+the magnetically hard epsilon ferrite was independently confirmed by
+temperature dependent magnetometry measurements. The depth-resolved x-ray and
+polarized neutron reflectometry reveal that the 10\,nm iron oxide layer at the
+interface has a lower density and a higher magnetization than the main volume
+of the $\varepsilon$-Fe$_2$O$_3$ film. The density and magnetic moment depth
+profiles derived from fitting the reflectometry data are in a good agreement
+with the presence of the magnetically degraded $\gamma$-Fe$_2$O$_3$ transition
+layer between MgO and $\varepsilon$-Fe$_2$O$_3$. The natural occurrence of the
+interface between magnetoelectric $\varepsilon$- and spin caloritronic
+$\gamma$- iron oxide phases can enable further opportunities to design novel
+all-oxide-on-semiconductor devices.",1907.11611v2
+1998-01-20,Electronic States and Excitation Spectra of Copper Oxides with Ladder and/or Chain,"Recently the superconductivity has been reported in the copper oxides
+(Sr,Ca)$_{14}$Cu$_{24}$O$_{41}$ with ladders and edge-sharing chains under
+pressure. In order to understand the mechanism of the superconductivity, it is
+crucial to clarify the distribution of self-doped holes. From the analysis of
+the optical conductivity by ionic model and exact diagonalization method, we
+confirm that with substituting Ca for Sr, the self-doped holes are transferred
+from the chains to the ladders. We also examine the electronic states of
+edge-sharing chain in a variety of copper oxides, and derive the effective
+Hamiltonian. The dependences of the magnetic interactions between Cu ions and
+of the hopping energies of the Zhang-Rice singlet on the bond angle of Cu-O-Cu
+are discussed.",9801195v1
+2000-10-20,Geometric frustration in the mixed layer pnictide oxides,"We present results from a Monte Carlo investigation of a simple bilayer model
+with geometrically frustrated interactions similar to those found in the mixed
+layer pnictide oxides $(Sr_{2}Mn_{3}Pn_{2}O_{2}, Pn=As,Sb).$ Our model is
+composed of two inequivalent square lattices with nearest neighbor intra- and
+interlayer interactions. We find a ground state composed of two independent
+N\'{e}el ordered layers when the interlayer exchange is an order of magnitude
+weaker than the intralayer exchange, as suggested by experiment. We observe
+this result independent of the number of layers in our model. We find evidence
+for local orthogonal order between the layers, but it occurs in regions of
+parameter space that are not experimentally realized. We conclude that
+frustration caused by nearest neighbor interactions in the mixed layer pnictide
+oxides is not sufficient to explain the long--range orthogonal order that is
+observed experimentally, and that it is likely that other terms (e.g., local
+anisotropies) in the Hamiltonian are required to explain the magnetic behavior.",0010303v1
+2002-01-15,Magnetic Resonant Mode in the Single-Layer High Temperature Superconductor Tl$_2$Ba$_2$Cu$_{6+δ}$,"An unusual spin excitation mode observed by neutron scattering has inspired
+numerous theoretical studies of the interplay between charged quasiparticles
+and collective spin excitations in the copper oxide high temperature
+superconductors. The mode has thus far only been observed in materials with
+crystal structures consisting of copper oxide bilayers, and it is notably
+absent in the single-layer compound La$_{2-x}$Sr$_{x}$CuO$_{4+\delta}$. Neutron
+scattering data now show that the mode is present in
+Tl$_2$Ba$_2$Cu$_{6+\delta}$, a single-layer compound with T$_c$ $\sim$ 90 K,
+thus demonstrating that it is a generic feature of the copper oxide
+superconductors, independent of the layer sequence. This restricts the
+theoretical models for the origin of the resonant mode and its role in the
+mechanism of high temperature superconductivity.",0201252v1
+2006-08-11,Scaling behavior in thermoelectric misfit cobalt oxides,"We investigate both thermoelectric and thermodynamic properties of the misfit
+cobalt oxide [Bi$_{1.7}$Co$_{0.3}$Ca$_{2}$O$_{4}$]$^{RS}_{0.6}$CoO$_{2}$. A
+large negative magnetothermopower is found to scale with both magnetic field
+and temperature revealing a significant spin entropy contribution to
+thermoelectric properties giving rise to a constant S$_0\approx$ 60 $\mu$V
+K$^{-1}$ equal to the high temperature asymptotic value of the spin 1/2
+entropy. Low temperature specific heat measurements allow us to determine an
+enhanced electronic part with $\gamma\approx$ 50 mJ (mol K$^{2}$)$^{-1}$
+attesting of strong correlations. Thereby, a critical comparison between
+[Bi$_{1.7}$Co$_{0.3}$Ca$_{2}$O$_{4}$]$^{RS}_{0.6}$CoO$_{2}$, other cobaltites
+as well as other materials reveals a universal behavior of the thermopower low
+temperature slope as a function of $\gamma$ testifying thus a purely electronic
+origin. This potentially generic scaling behavior suggests here that the high
+room temperature value of the thermopower in misfit cobalt oxides results from
+the addition of a spin entropy contribution to an enlarged electronic one.",0608264v1
+2008-09-05,Structure-Property Relation of SrTiO3-LaAlO3 Interfaces,"A large variety of transport properties have been observed at the interface
+between the insulating oxides SrTiO3 and LaAlO3 such as insulation, 2D
+interface metallicity, 3D bulk metallicity, Kondo scattering, magnetism and
+superconductivity. The relation between the structure and the properties of the
+SrTiO3-LaAlO3 interface can be explained in a meaningful way by taking into
+account the relative contribution of three structural aspects: oxygen
+vacancies, structural deformations (including cation disorder) and electronic
+interface reconstruction. The emerging phase diagram is much richer than for
+related bulk oxides due to the occurrence of interface electronic
+reconstruction. The observation of this interface phenomenon is a display of
+recent advances in thin film deposition and characterization techniques, and
+provides an extension to the range of exceptional electronic properties of
+complex oxides.",0809.1068v1
+2008-12-20,Distinct transport behaviors of LaFe1-yCoyAsO1-xFx (x=0.11) between the superconducting and nonsuperconducting metallic y regions divided by y ~ 0.05,"Electrical resistivities, Hall coefficients and thermoelectric powers have
+been measured for polycrystalline samples of LaFe1-yCoyAsO1-xFx (x=0.11) with
+various values of y. The results show that there exists clear distinction of
+these transport behaviors between the superconducting and nonsuperconducting
+metallic regions of y divided by the boundary value yc~0.05. We have found that
+the behaviors in both regions are very similar to those of high-Tc Cu oxides in
+the corresponding phases. If they reflect, as in the case of Cu oxides, effects
+of strong magnetic fluctuations, the energy scale of the fluctuations is
+considered to be smaller than that of the high Cu oxides by a factor of ~1/2.
+Arguments on the electronic nature and superconducting symmetry are presented
+on the basis of the observed small rate of the Tc suppression rate by the Co
+doping.",0812.3949v1
+2009-03-19,Superconductivity at 17 K in (Fe2P2)(Sr4Sc2O6): a new superconducting layered pnictide oxide with a thick perovskite oxide layer,"A new layered oxypnictide (Fe2P2)(Sr4Sc2O6) have been synthesized by
+solid-state reaction. This material has an alternating layer stacking structure
+of anti-fluorite Fe2P2 and perovskite-based Sr4Sc2O6 oxide layers. Space group
+of the material is P4/nmm and lattice constants a and c are 4.016 A and 15.543
+A, respectively. The interlayer Fe-Fe distance corresponding to the c-axis
+length is the longest ever reported in the iron-based oxypnictide systems. In
+both magnetization and resistivity measurements, the present compound exhibited
+superconductivity below 17 K, which is much higher than that of LaFePO and the
+highest in arsenic-free iron-based oxypnictide systems under ambient pressure.",0903.3314v3
+2009-07-19,Hyperthermia HeLa cell treatment with silica coated manganese oxide nanoparticles,"The effect of a high frequency alternating magnetic field on HeLa tumour
+cells incubated with ferromagnetic nanoparticles of manganese oxide perovskite
+La0.56(SrCa)0.22MnO3 have been studied. The particles were subjected to a size
+selection process and coated with silica to improve their biocompatibility. The
+control assays made with HeLa tumour cells showed that cell survival and growth
+rate were not affected by the particle internalization in cells, or by the
+electromagnetic field on cells without nanoparticles. However, the application
+of an alternating electromagnetic field to cells incubated with this silica
+coated manganese oxide induced a significant cellular damage that finally lead
+to cell death by an apoptotic mechanism. Cell death is triggered even thought
+the temperature increase in the cell culture during the hyperthermia treatment
+is lower than 0.5 C.",0907.3278v2
+2009-08-19,Supercell band calculations and correlation for high-$T_C$ copper oxide superconductors,"First principle band calculations based on local versions of density
+functional theory (DFT), together with results from nearly free-electron
+models, can describe many typical but unusual properties of the high-$T_C$
+copper oxides. The methods and a few of the most important results are
+reviewed. Some additional calculations are presented and the problems with the
+commonly used approximate versions of DFT for oxides are discussed with a few
+ideas for corrections. It is concluded that rather modest corrections to the
+approximate DFT, without particular assumptions about strong correlation, can
+push the ground state towards anti-ferro magnetic (AFM) order. Spin
+fluctuations interacting with phonons are crucial for the mechanism of
+superconductivity in this scenario.",0908.2767v1
+2009-11-16,Doping graphene by adsorption of polar molecules at the oxidized zigzag edges,"We have theoretically investigated the electronic and magnetic properties of
+graphene whose zigzag edges are oxidized. The alteration of these properties by
+adsorption of $\mathrm{H_{2}O}$ and $\mathrm{NH_3}$ molecules have been
+considered. It was found that the adsorbed molecules form a cluster along the
+oxidized zigzag edges of graphene due to interaction with the electro-negative
+oxygen. Graphene tends to donate a charge to the adsorbates through the oxygen
+atoms and the efficiency of donation depends on the intermolecular distance and
+on the location of the adsorbed molecules relative to the plane of graphene. It
+was found that by appropriate selection of the adsorbates, a controllable and
+gradual growth of $p$-doping in graphene with a variety of adsorbed molecules
+can be achieved.",0911.3046v2
+2010-03-16,All Magnesium diboride Josephson Junctions with MgO and native oxide barriers,"We present results on all-MgB2 tunnel junctions, where the tunnel barrier is
+deposited MgO or native-oxide of base electrode. For the junctions with MgO,
+the hysteretic I-V curve resembles a conventional underdamped Josephson
+junction characteristic with critical current-resistance product nearly
+independent of the junction area. The dependence of the critical current with
+temperature up to 20 K agrees with the [Ambegaokar and Baratoff, Phys. Rev.
+Lett. 10, 486 (1963)] expression. For the junctions with native-oxide,
+conductance at low bias exhibits subgap features while at high bias reveals
+thick barriers. As a result no supercurrent was observed in the latter, despite
+the presence of superconducting-gaps to over 30 K.",1003.3158v1
+2010-04-02,First Principles NMR Signatures of Graphene Oxide,"Nuclear magnetic resonance (NMR) has been widely used in the graphene oxide
+(GO) structure study. However, the detailed relationship between its
+spectroscopic features and the GO structural configuration has remained
+elusive. Based on first principles $^{13}$C chemical shift calculations using
+the gauge including projector augmented waves (GIPAW) method, we provide a
+spectrum-structure connection. Chemical shift of carbon is found to be very
+sensitive to atomic environment, even with an identical oxidation group.
+Factors determining the chemical shifts for epoxy and hydroxy groups have been
+discussed. GO structures previously reported in the literature have been
+checked from the NMR point of view. The energetically favorable hydroxy chain
+structure is not expected to be widely existed in real GO samples according to
+our NMR simulations. The epoxy pair we proposed previously is also supported by
+chemical shift calculations.",1004.0333v1
+2010-11-21,Localized vs. delocalized character of charge carriers in LaAlO3/ SrTiO3 superlattices,"Understanding the nature of electrical conductivity, superconductivity and
+magnetism between layers of oxides is of immense importance for the design of
+electronic devices employing oxide heterostructures. We demonstrate that
+resonant inelastic X-ray scattering can be applied to directly probe the
+carriers in oxide heterostructures. Our investigation on epitaxially grown
+LaAlO3/SrTiO3 superlattices unambiguously reveals the presence of both
+localized and delocalized Ti 3d carriers. These two types of carriers are
+caused by oxygen vacancies and electron transfer due to the polar discontinuity
+at the interface. This result allows explaining the reported discrepancy
+between theoretically calculated and experimentally measured carrier density
+values in LaAlO3/SrTiO3 heterostructures.",1011.4674v1
+2011-10-19,Synthesis of novel rare earth - iron oxide chalcogenides with the La2Fe2O3Se2 structure,"Our searches for new oxide chalcogenides of rare earths and Fe, Co, Ni, and
+Zn resulted in preparation of two new compounds Ce2Fe2O3S2 and Pr2Fe2O3S2 which
+are isostructural to La2Fe2O3Se2 and Sm2Ti2O3Sb2. Crystal structures of the new
+compounds Ce2Fe2O3S2 and Pr2Fe2O3S2 were determined from powder X-ray
+diffraction data. Magnetic measurements were performed for Ce2Fe2O3S2 and
+revealed behavior very similar to that of isostructural oxide chalcogenides of
+iron and pnictides of titanium. In particular, no superconductivity was
+observed down to 4 K. Crystal chemical factors determining the stability of the
+La2Fe2O3Se2 structure type are discussed.",1110.4234v1
+2012-02-04,Phonon anomalies and dynamic stripes,"Stripe order where electrons self-organize into alternating periodic
+charge-rich and magnetically-ordered charge-poor parallel lines was proposed as
+a way of optimizing the kinetic energy of holes in a doped Mott insulator.
+Static stripes detected as extra peaks in diffraction patterns, appear in a
+number of oxide perovskites as well as some other systems. The more
+controversial dynamic stripes, which are not detectable by diffraction, may be
+universally present in copper oxide superconductors. Thus it is important to
+learn how to detect dynamic stripes as well as to understand their influence on
+electronic properties. This review article focuses on lattice vibrations
+(phonons) that might show signatures of the charge component of dynamic
+stripes. The first part of the article describes recent progress in learning
+about how the phonon signatures of different types of electronic charge
+fluctuations including stripes can be distinguished from purely structural
+instabilities and from each other. Then I will focus on the evidence for
+dynamic stripes in the phonon spectra of copper oxide superconductors.",1202.0852v2
+2012-03-30,Preventing the reconstruction of the polar discontinuity at oxide heterointerfaces,"Perovskite oxide heteroepitaxy receives much attention because of the
+possibility to com- bine the diverse functionalities of perovskite oxide
+building blocks. A general boundary con- dition for the epitaxy is the presence
+of polar discontinuities at heterointerfaces. These polar discontinuities
+result in reconstructions, often creating new functionalities at the interface.
+However, for a significant number of materials these reconstructions are
+unwanted as they alter the intrinsic materials properties at the interface.
+Therefore, a strategy to eliminate this reconstruction of the polar
+discontinuity at the interfaces is required. We show that the use of
+compositional interface engineering can prevent the reconstruction at the
+La0.67Sr0.33MnO3/SrTiO3 (LSMO/STO) interface. The polar discontinuity at this
+interface can be removed by the insertion of a single La0.33Sr0.67O layer,
+resulting in improved interface magnetization and electrical conductivity.",1203.6729v1
+2012-07-19,Strongly coupled phase transition in ferroelectric/correlated electron oxide heterostructures,"We fabricated ultrathin ferroelectric/correlated electron oxide
+heterostructures composed of the ferroelectric Pb(Zr0.2Ti0.8)O3 and the
+correlated electron oxide (CEO) La0.8Sr0.2MnO3 on SrTiO3 substrates by pulsed
+laser epitaxy. The hole accumulation in the ultrathin CEO layer was
+substantially modified by heterostructuring with the ferroelectric layer,
+resulting in an insulator-metal transition. In particular, our thickness
+dependent study showed that drastic changes in transport and magnetic
+properties were strongly coupled to the modulation of charge carriers by
+ferroelectric field effect, which was confined to the vicinity of the
+interface. Thus, our results provide crucial evidence that strong ferroelectric
+field effect control can be achieved in ultrathin (10 nm) heterostructures,
+yielding at least a 100,000-fold change in resistivity.",1207.4723v1
+2013-10-31,Origin of two-dimensional electron gases at oxide interfaces: insights from theory,"The response of oxide thin films to polar discontinuities at interfaces and
+surfaces has generated an enormous activity due to the variety of interesting
+effects it gives rise to. A case in point is the discovery of the electron gas
+at the interface between LaAlO3 and SrTiO3, which has since been shown to be
+quasi-two-dimensional, switchable, magnetic and/or superconducting. Despite
+these findings, the origin of the two-dimensional electron gas is highly
+debated and several possible mechanisms remain. Here we review the main
+proposed mechanisms and attempt to model expected effects in a quantitative way
+with the ambition of better constraining what effects can/cannot explain the
+observed phenomenology. We do it in the framework of a phenomenological model
+for understanding electronic and/or redox screening of the chemical charge in
+oxide heterostructures. We also discuss the effect of intermixing, both
+conserving and non-conserving the total stoichiometry.",1310.8427v2
+2013-12-30,Correlation effects in (111) bilayers of perovskite transition-metal oxides,"We investigate the correlation-induced Mott, magnetic, and topological phase
+transitions in artificial (111) bilayers of perovskite transition-metal oxides
+LaAuO$_3$ and SrIrO$_3$ for which the previous density-functional theory
+calculations predicted topological insulating states. Using the
+dynamical-mean-field theory with realistic band structures and Coulomb
+interactions, LaAuO$_3$ bilayer is shown to be far away from a Mott insulating
+regime, and a topological-insulating state is robust. On the other hand,
+SrIrO$_3$ bilayer is on the verge of an orbital-selective topological Mott
+transition and turns to a trivial insulator by an antiferromagnetic ordering.
+Oxide bilayers thus provide a novel class of topological materials for which
+the interplay between the spin-orbit coupling and electron-electron
+interactions is a fundamental ingredient.",1401.0009v2
+2014-12-16,Terahertz spectroscopy of N$^{18}$O and isotopic invariant fit of several nitric oxide isotopologs,"A tunable far-infrared laser sideband spectrometer was used to investigate a
+nitric oxide sample enriched in 18O between 0.99 and 4.75 THz. Regular,
+electric dipole transitions were recorded between 0.99 and 2.52 THz, while
+magnetic dipole transitions between the 2Pi(1/2) and 2Pi(3/2) spin-ladders were
+recorded between 3.71 and 4.75 THz. These data were combined with lower
+frequency data of N(18)$O (unlabeled atoms refer to (14)N and (16)O,
+respectively), with rotational data of NO, (15)NO, N(17)O, and (15)N(18)O, and
+with heterodyne infrared data of NO to be subjected to one isotopic invariant
+fit. Rotational, fine and hyperfine structure parameters were determined along
+with vibrational, rotational, and Born-Oppenheimer breakdown corrections. The
+resulting spectroscopic parameters permit prediction of rotational spectra
+suitable for the identification of various nitric oxide isotopologs especially
+in the interstellar medium by means of rotational spectroscopy.",1412.4974v1
+2015-11-19,Spin-density functional theories and their $+U$ and $+J$ extensions: a comparative study of transition metals and transition metal oxides,"Previous work on the physical content of exchange correlation functionals
+that depend on both charge and spin densities is extended to elemental
+transition metals and a wider range of perovskite transition metal oxides. A
+comparison of spectra and magnetic moments calculated using exchange
+correlation functionals depending on charge density only or on both charge and
+spin densities, as well as the $+U$ and $+J$ extensions of these methods
+confirms previous conclusions that the spin-dependent part of the exchange
+correlation functional provides an effective Hund's interaction acting on the
+transition metal $d$ orbitals. For the local spin density approximation and
+spin-dependent Perdew-Burke-Ernzerhof generalized gradient approximation, the
+effective Hund's exchange is found to be larger than 1 eV. The results indicate
+that at least as far as applications to transition metals and their oxides are
+concerned, $+U$, $+J$ and +dynamical mean field theory extensions of density
+functional theory should be based on exchange-correlation functionals of charge
+density only.",1511.06042v1
+2016-04-19,Dirac topological insulator in the d$_{z^2}$ manifold of a honeycomb oxide,"We show by means of ab initio calculations and tight-binding modeling that an
+oxide system based on a honeycomb lattice can sustain topologically non-trivial
+states if a single orbital dominates the spectrum close to the Fermi level. In
+such situation, the low energy spectra is described by two Dirac equations that
+become non-trivially gapped when spin-orbit coupling (SOC) is switched on. We
+provide one specific example for this but the recipe is general. We discuss a
+realization of this starting from a conventional spin-a-half honeycomb
+antiferromagnet whose states close to the Fermi energy are d$_{z^2}$ orbitals.
+Switching off magnetism by atomic substitution and ensuring that the electronic
+structure becomes two-dimensional is sufficient for topologicality to arise in
+such a system. We show that the gap in such model scales linearly with SOC,
+opposed to other oxide-based topological insulators, where smaller gaps tend to
+appear by construction of the lattice. We also provide a study of the quantum
+Hall effect in such system, showing the close connections with the physics of
+graphene but in a d-electron system.",1604.05554v2
+2017-01-30,Effect of iron oxide loading on magnetoferritin structure in solution as revealed by SAXS and SANS,"Synthetic biological macromolecule of magnetoferritin containing an iron
+oxide core inside a protein shell (apoferritin) is prepared with different
+content of iron. Its structure in aqueous solution is analyzed by small-angle
+synchrotron X-ray (SAXS) and neutron (SANS) scattering. The loading factor (LF)
+defined as the average number of iron atoms per protein is varied up to LF=800.
+With an increase of the LF, the scattering curves exhibit a relative increase
+in the total scattered intensity, a partial smearing and a shift of the match
+point in the SANS contrast variation data. The analysis shows an increase in
+the polydispersity of the proteins and a corresponding effective increase in
+the relative content of magnetic material against the protein moiety of the
+shell with the LF growth. At LFs above ~150, the apoferritin shell undergoes
+structural changes, which is strongly indicative of the fact that the shell
+stability is affected by iron oxide presence.",1702.00350v1
+2017-03-11,Competing weak localization and weak antilocalization in amorphous indium-gallium-zinc-oxide thin-film transistors,"We have investigated the gate-voltage dependence and the temperature
+dependence of the magnetoconductivity of amorphous indium-gallium-zinc-oxide
+thin-film transistors. A weak-localization feature is observed at small
+magnetic fields on top of an overall negative magnetoconductivity at higher
+fields. An intriguing controllable competition between weak localization and
+weak antilocalization is observed by tuning the gate voltage or varying the
+temperature. Our findings reflect controllable quantum interference competition
+in the electron systems in amorphous indium-gallium-zinc-oxide thin-film
+transistors.",1703.04007v1
+2017-08-01,Ultrafast Modification of the Polarity at LaAlO$_3$/SrTiO$_3$ Interfaces,"Oxide growth with semiconductor-like accuracy has led to atomically precise
+thin films and interfaces that exhibit a plethora of phases and functionalities
+not found in the oxide bulk material. This yielded spectacular discoveries such
+as the conducting, magnetic or even superconducting LaAlO$_3$/SrTiO$_3$
+interfaces separating two prototypical insulating perovskite materials. All
+these investigations, however, consider the static state at the interface,
+although studies on fast oxide interface dynamics would introduce a powerful
+degree of freedom to understanding the nature of the LaAlO$_3$/SrTiO$_3$
+interface state. Here we show that the polarization state at the
+LaAlO$_3$/SrTiO$_3$ interface can be optically enhanced or attenuated within
+picoseconds. Our observations are explained by a model based on charge
+propagation effects in the interfacial vicinity and transient polarization
+buildup at the interface.",1708.00198v1
+2017-08-15,Polarizing oxygen vacancies in insulating metal oxides under high electric field,"We demonstrate a thermodynamic formulation to quantify defect formation
+energetics in an insulator under high electric field. As a model system, we
+analyzed neutral oxygen vacancies (color centers) in alkaline-earth-metal
+binary oxides using density functional theory, Berry phase calculations, and
+maximally localized Wannier functions. Work of polarization lowers the field
+dependent electric Gibbs energy of formation of this defect. This is attributed
+mainly to the ease of polarizing the two electrons trapped in the vacant site,
+and secondarily to the defect induced reduction in bond stiffness and softening
+of phonon modes. The formulation and analysis have implications for
+understanding the behavior of insulating oxides in electronic, magnetic,
+catalytic, and electrocaloric devices under high electric field.",1708.04598v1
+2017-08-30,Depth profiling charge accumulation from a ferroelectric into a doped Mott insulator,"The electric field control of functional properties is a crucial goal in
+oxide-based electronics. Non-volatile switching between different resistivity
+or magnetic states in an oxide channel can be achieved through charge
+accumulation or depletion from an adjacent ferroelectric. However, the way in
+which charge distributes near the interface between the ferroelectric and the
+oxide remains poorly known, which limits our understanding of such switching
+effects. Here we use a first-of-a-kind combination of scanning transmission
+electron microscopy with electron energy loss spectroscopy,
+near-total-reflection hard X-ray photoemission spectroscopy, and ab-initio
+theory to address this issue. We achieve a direct, quantitative, atomic-scale
+characterization of the polarization-induced charge density changes at the
+interface between the ferroelectric BiFeO3 and the doped Mott insulator
+Ca1-xCexMnO3, thus providing insight on how interface-engineering can enhance
+these switching effects.",1708.09160v1
+2018-05-01,Averievite: a copper oxide kagome antiferromagnet,"Averievite, Cu$_5$V$_2$O$_{10}$(CsCl), is an oxide mineral composed of
+Cu$^{2+}$ kagome layers sandwiched by Cu$^{2+}$-V$^{5+}$ honeycomb layers. We
+have synthesized this oxide and investigated its properties from ab initio
+calculations along with susceptibility and specific heat measurements. The data
+indicate a Curie-Weiss temperature of 185 K as well as long-range magnetic
+order at 24 K due to the significant interlayer coupling from the honeycomb
+copper ions. This order is suppressed by substituting these coppers by
+isoelectronic zinc, suggesting that Zn-substituted averievite is a promising
+spin liquid candidate. A further proposed substitution that replaces V$^{5+}$
+by Ti$^{4+}$ not only dopes the material, but is predicted to give rise to a
+two-dimensional electronic structure featuring Dirac crossings. As such,
+averievite is an attractive platform for S=1/2 kagome physics with the
+potential for realizing novel electronic states.",1805.00561v2
+2014-05-13,Real structure of lattice matched GaAs-Fe3Si core-shell nanowires,"GaAs nanowires and GaAs-Fe3Si core-shell nanowire structures were grown by
+molecular-beam epitaxy on oxidized Si(111) substrates and characterized by
+transmission electron microscopy (TEM) and X-ray diffraction (XRD). Ga droplets
+were formed on the oxide surface, and the semiconducting GaAs nanowires grew
+epitaxially via the vapor-liquid-solid mechanism as single-crystals from holes
+in the oxide film. We observed two stages of growth of the GaAs nanowires,
+first the regular growth and second the residual growth after the Ga supply was
+finished. The magnetic Fe3Si shells were deposited in an As-free chamber. They
+completely cover the GaAs cores although they consist of small grains.
+High-resolution TEM micrographs depict the differently oriented grains in the
+Fe3Si shells. Selected area diffraction of electrons and XRD gave further
+evidence that the shells are textured and not single crystals. Facetting of the
+shells was observed, which lead to thickness inhomogeneities of the shells.",1405.3143v2
+2015-12-17,New Honeycomb Iridium (V) Oxides: NaIrO$_3$ and Sr$_3$CaIr$_2$O$_9$,"We report the structures and physical properties of two new iridates,
+NaIrO$_3$ and Sr$_3$CaIr$_2$O$_9$, both of which contain continuous
+two-dimensional honeycomb connectivity. NaIrO3 is produced by room temperature
+oxidative deintercalation of sodium from Na$_2$IrO$_3$, and contains
+edge-sharing IrO6 octahedra that form a planar honeycomb lattice.
+Sr$_3$CaIr$_2$O$_9$, produced via conventional solid-state synthesis, hosts a
+buckled honeycomb lattice with novel corner-sharing connectivity between IrO6
+octahedra. Both of these new compounds are comprised of Ir$^{5+}$ (5$d^4$) and
+exhibit negligible magnetic susceptibility. They are thus platforms to
+investigate the origin of the nonmagnetic behavior exhibited by Ir$^{5+}$
+oxides, and provide the first examples of a $J$ = 0 state on a honeycomb
+lattice.",1512.05804v1
+2017-10-02,Localized Control of Curie Temperature in Perovskite Oxide Film by Capping-layer- induced Octahedral Distortion,"With reduced dimensionality, it is often easier to modify the properties of
+ultra-thin films than their bulk counterparts. Strain engineering, usually
+achieved by choosing appropriate substrates, has been proven effective in
+controlling the properties of perovskite oxide films. An emerging alternative
+route for developing new multifunctional perovskite is by modification of the
+oxygen octahedral structure. Here we report the control of structural oxygen
+octahedral rotation in ultra-thin perovskite SrRuO3 films by the deposition of
+a SrTiO3 capping layer, which can be lithographically patterned to achieve
+local control. Using a scanning Sagnac magnetic microscope, we show increase in
+the Curie temperature of SrRuO3 due to the suppression octahedral rotations
+revealed by the synchrotron x-ray diffraction. This capping-layer-based
+technique may open new possibilities for developing functional oxide materials.",1710.00729v1
+2017-10-24,La interstitial defect-induced insulator-metal transition in oxide heterostructures LaAlO3/SrTiO3,"Perovskite oxide interfaces have attracted tremendous research interest for
+their fundamental physics and promising all-oxide electronics applications.
+Here, based on first-principles calculations, we propose a novel surface La
+interstitial promoted interface insulator-metal transition in LaAlO3/SrTiO3
+(110). Compared with surface oxygen vacancies, which play a determining role on
+the insulator-metal transition of LaAlO3/SrTiO3 (001) interfaces, we find that
+surface La interstitials can be more experimentally realistic and accessible
+for manipulation and more stable in ambient atmospheric environment.
+Interestingly, these surface La interstitials also induce significant
+spin-splitting states with Ti dyz/dxz character at conducting LaAlO3/SrTiO3
+(110) interface. On the other hand, for insulating LaAlO3/SrTiO3 (110) (<4 unit
+cells LaAlO3 thickness), a distortion between La (Al) and O atoms is found at
+the LaAlO3 side, partially compensating the polarization divergence. Our
+results reveal the origin of metal-insulator transition in LaAlO3/SrTiO3 (110)
+heterostructures, and also shed light on the manipulation of the superior
+properties of LaAlO3/SrTiO3 (110) for new possibilities of electronic and
+magnetic applications.",1710.08652v1
+2018-01-12,Control of oxidation and spin state in a single-molecule junction,"The oxidation and spin state of a metal-organic molecule determine its
+chemical reactivity and magnetic properties. Here, we demonstrate the
+reversible control of the oxidation and spin state in a single Fe-porphyrin
+molecule in the force field of the tip of a scanning tunneling microscope.
+Within the regimes of half-integer and integer spin state, we can further track
+the evolution of the magnetocrystalline anisotropy. Our experimental results
+are corroborated by density functional theory and wave function theory. This
+combined analysis allows us to draw a complete picture of the molecular states
+over a large range of intramolecular deformations.",1801.04162v1
+2019-09-27,Enhancement of spin mixing conductance in La$_{0.7}$Sr$_{0.3}$MnO$_{3}$/LaNiO$_{3}$/SrRuO$_{3}$ heterostructures,"We investigate spin pumping and the effective spin mixing conductance in
+heterostructures based on magnetic oxide trilayers composed of
+La$_{0.7}$Sr$_{0.3}$MnO$_3$ (LSMO), LaNiO$_3$ (LNO), and SrRuO$_3$ (SRO). The
+heterostructures serve as a model system for an estimation of the effective
+spin mixing conductance at the different interfaces. Our results show that by
+introducing a LNO interlayer between LSMO and SRO, the total effective spin
+mixing conductance increases due to the much more favourable interface of
+LSMO/LNO with respect to the LSMO/SRO interface. Neverheless, the spin current
+into the SRO does not decrease because of the spin diffusion length of
+$\lambda_\text{LNO}\approx$3.3 nm in the LNO. This value is two times higher
+than that of SRO. Our results show the potential of using oxide interfaces to
+tune the effective spin mixing conductance in heterostructures and to bring
+novel functionalities into spintronics by implementing complex oxides.",1909.12766v1
+2020-04-21,Electrical and acoustic self-oscillations in an epitaxial oxide for neuromorphic applications,"Developing materials that can lead to compact versions of artificial neurons
+(neuristors) and synapses (memristors) is the main aspiration of the nascent
+neuromorphic materials research field. Oscillating circuits are interesting as
+neuristors, emulating the firing of action potentials. We present
+room-temperature self-oscillating devices fabricated from epitaxial thin films
+of semiconducting TbMnO3. We show that these electrical oscillations induce
+concomitant mechanical oscillations that produce audible sound waves, offering
+an additional degree of freedom to interface with other devices. The intrinsic
+nature of the mechanism governing the oscillations gives rise to a high degree
+of control and repeatability. Obtaining such properties in an epitaxial
+perovskite oxide, opens the way towards combining self-oscillating properties
+with those of other piezoelectric, ferroelectric, or magnetic perovskite oxides
+to achieve hybrid neuristor-memristor functionality in compact heterostuctures.",2004.09903v2
+2017-04-29,Improved electronic structure and magnetic exchange interactions in transition metal oxides,"We discuss the application of the Agapito Curtarolo and Buongiorno Nardelli
+(ACBN0) pseudo-hybrid Hubbard density functional to several transition metal
+oxides. ACBN0 is a fast, accurate and parameter-free alternative to traditional
+DFT+$U$ and hybrid exact exchange methods. In ACBN0, the Hubbard energy of
+DFT+$U$ is calculated via the direct evaluation of the local Coulomb and
+exchange integrals in which the screening of the bare Coulomb potential is
+accounted for by a renormalization of the density matrix. We demonstrate the
+success of the ACBN0 approach for the electronic properties of a series
+technologically relevant mono-oxides (MnO, CoO, NiO, FeO, both at equilibrium
+and under pressure). We also present results on two mixed valence compounds,
+Co$_3$O$_4$ and Mn$_3$O$_4$. Our results, obtained at the computational cost of
+a standard LDA/PBE calculation, are in excellent agreement with hybrid
+functionals, the GW approximation and experimental measurements.",1705.00194v1
+2017-09-22,Universality in the Electronic Structure of 3d Transition Metal Oxides,"Electronic structure of strongly correlated transition metal oxides (TMOs) is
+a complex phenomenon due to competing interaction among the charge, spin,
+orbital and lattice degrees of freedom. Often individual compounds are examined
+to explain certain properties associated with these compounds or in rare cases
+few members of a family are investigated to define a particular trend exhibited
+by that family. Here, with the objective of generalization, we have
+investigated the electronic structure of three families of compounds, namely,
+highly symmetric cubic mono-oxides, symmetry-lowered spinels and asymmetric
+olivine phosphates, through density functional calculations. From the results
+we have developed empirical hypotheses involving electron hopping,
+electron-lattice coupling, Hund's rule coupling, strong correlation and d-band
+filling. These hypotheses, classified through the point group symmetry of the
+transition metal - oxygen complexes, can be useful to understand and predict
+the electronic and magnetic structure of 3d TMOs.",1709.07868v1
+2018-12-12,Room-temperature ferromagnetic insulating state in highly cation-ordered epitaxial oxide double perovskite,"Ferromagnetic insulators (FMIs) are one of the most important components in
+developing dissipationless electronic and spintronic devices. However, since
+ferromagnetism generally accompanies metallicity, FMIs are innately rare to
+find in nature. Here, novel room-temperature FMI films are epitaxially
+synthesized by deliberate control of the ratio of two B-site cations in the
+double perovskite Sr2FeReO6. In contrast to the known ferromagnetic metallic
+phase in stoichiometric Sr2FeReO6, a FMI state with a high Curie temperature
+(Tc~400 K) and a large saturation magnetization (MS~1.8 {\mu}B/f.u.) is found
+in highly cation-ordered Fe-rich phases. The stabilization of the FMI state is
+attributed to the formation of extra Fe3+-Fe3+ and Fe3+-Re6+ bonding states,
+which originate from the excess Fe. The emerging FMI state by controlling
+cations in the epitaxial oxide perovskites opens the door to developing novel
+oxide quantum materials & heterostructures.",1812.04953v1
+2020-06-02,Spin pumping and inverse spin Hall effect in iridium oxide,"Large charge-to-spin conversion (spin Hall angle) and spin Hall conductivity
+are prerequisites for development of next generation power efficient spintronic
+devices. In this context, heavy metals (e.g. Pt, W etc.), topological
+insulators, antiferromagnets are usually considered because they exhibit high
+spin-orbit coupling (SOC). In addition to the above materials, 5d transition
+metal oxide e.g. Iridium Oxide (IrO 2 ) is a potential candidate which exhibits
+high SOC strength. Here we report a study of spin pumping and inverse spin Hall
+effect (ISHE), via ferromagnetic resonance (FMR), in IrO 2 /CoFeB system. We
+identify the individual contribution of spin pumping and other spin
+rectification effects in the magnetic layer, by investigating the in-plane
+angular dependence of ISHE signal. Our analysis shows significant contribution
+of spin pumping effect to the ISHE signal. We show that polycrystalline IrO 2
+thin film exhibits high spin Hall conductivity and spin Hall angle which are
+comparable to the values of Pt.",2006.01865v2
+2020-06-06,Controlling Metal-Insulator Transitions in Vanadium Oxide Thin Films by Modifying Oxygen Stoichiometry,"Vanadium oxides are strongly correlated materials which display
+metal-insulator transitions as well as various structural and magnetic
+properties that depend heavily on oxygen stoichiometry. Therefore, it is
+crucial to precisely control oxygen stoichiometry in these materials,
+especially in thin films. This work demonstrates a high-vacuum gas evolution
+technique which allows for the modification of oxygen concentration in VOX thin
+films by carefully tuning thermodynamic conditions. We were able to control the
+evolution between VO2, V3O5, and V2O3 phases on sapphire substrates, overcoming
+the narrow phase stability of adjacent Magn\'eli phases. A variety of annealing
+routes were found to achieve the desired phases and eventually to control the
+metal-insulator transition (MIT). The pronounced MIT of the transformed films
+along with the detailed structural investigations based on x-ray diffraction
+measurements and reciprocal space mapping show that optimal stoichiometry is
+obtained and stabilized. Using this technique, we find that the thin film V-O
+phase diagram differs from that of the bulk material due to strain and finite
+size effects. Our study demonstrates new pathways to strategically tune the
+oxygen stoichiometry in complex oxides and provides a roadmap for understanding
+the phase stability of VOX thin films.",2006.03998v1
+2020-08-06,Crossover between Photochemical and Photothermal Oxidations of Atomically Thin Magnetic Semiconductor CrPS4,"Many two-dimensional (2D) semiconductors represented by transition metal
+dichalcogenides have tunable optical bandgaps in the visible or near IR-range
+standing as a promising candidate for optoelectronic devices. Despite this
+potential, however, their photoreactions are not well understood or
+controversial in the mechanistic details. In this work, we report a unique
+thickness-dependent photoreaction sensitivity and a switchover between two
+competing reaction mechanisms in atomically thin chromium thiophosphate
+(CrPS4), a two-dimensional antiferromagnetic semiconductor. CrPS4 showed a
+threshold power density 2 orders of magnitude smaller than that for MoS2
+obeying a photothermal reaction route. In addition, reaction cross section
+quantified with Raman spectroscopy revealed distinctive power dependences in
+the low and high power regimes. On the basis of optical in situ thermometric
+measurements and control experiments against O2, water, and photon energy, we
+proposed a photochemical oxidation mechanism involving singlet O2 in the low
+power regime with a photothermal route for the other. We also demonstrated a
+highly effective encapsulation with Al2O3 as a protection against the
+destructive photoinduced and ambient oxidations.",2008.02468v1
+2021-02-08,"Schottky Barrier Heights of Defect-free Metal/ZnO, CdO, MgO and SrO Interfaces","The Schottky barrier heights (SBHs) of defect-free interfaces of ZnO, CdO,
+MgO and SrO with various metals and different terminations are investigated by
+density functional supercell calculations. The oxide bands are corrected for
+their density functional band gap error by applying U-type treatment to their
+metal-d and O-p states where necessary. The p-type SBHs are found to decrease
+linearly with increasing metal work function. The pinning factor S of the
+non-polar and polar interfaces are similar for each oxide. S is found to be
+0.26, 0.56, 0.74 and 0.96 for CdO, ZnO, MgO and SrO, respectively, with S
+increasing for increased oxide ionicity. The calculated pinning factors are
+generally consistent with the metal-induced gap states (MIGS) model in terms of
+variation with ionicity and dielectric constant. A significant shift of SBHs
+from the non-polar to the polar interfaces of 0.4 eV, 1 eV and 0.5 eV for ZnO,
+MgO and SrO, respectively, can be explained by an interfacial dipole. Our
+results are also useful to describe Co,Fe|MgO interfaces in magnetic tunnel
+junctions.",2102.04482v1
+2021-10-26,Evidence for unconventional superconductivity in a spinel oxide,"The charge frustration with the mixed-valence state inherent to
+LiTi$_2$O$_4$, which is found to be a unique spinel oxide superconductor, is
+the impetus for paying special attention to reveal the existence of intriguing
+superconducting properties. Here, we report a pronounced fourfold rotational
+symmetry of the superconductivity in high-quality single-crystalline
+LiTi$_2$O$_4$ (001) thin films. Both the magnetoresistivity and upper critical
+field under an applied magnetic field manifest striking fourfold oscillations
+deep inside the superconducting state, whereas the anisotropy vanishes in the
+normal state, demonstrating that it is an intrinsic property of the
+superconducting phase. We attribute this behavior to the unconventional
+$d$-wave superconducting Cooper pairs with the irreducible representation of
+$E_g$ protected by $O_h$ point group in LiTi$_2$O$_4$. Our findings demonstrate
+the unconventional character of the pairing interaction in a three-dimensional
+spinel oxide superconductor and shed new light on the pairing mechanism of
+unconventional superconductivity.",2110.13397v2
+2023-06-21,Epitaxy enhancement in oxide/tungsten heterostructures by harnessing the interface adhesion,"The conditions whereby epitaxy is achieved are commonly believed to be mostly
+governed by misfit strain. We report on a systematic investigation of growth
+and interface structure of single crystalline tungsten thin films on two
+different metal oxide substrates, Al$_{2}$O$_{3}$ ($11\bar{2}0$) and MgO
+($001$). We demonstrate that despite a significant mismatch, enhanced crystal
+quality is observed for tungsten grown on the sapphire substrates. This is
+promoted by stronger adhesion and chemical bonding with sapphire compared to
+magnesium oxide, along with the restructuring of the tungsten layers close to
+the interface. The latter is supported by ab initio calculations using density
+functional theory. Finally, we demonstrate the growth of magnetic
+heterostructures consisting of high-quality tungsten layers in combination with
+ferromagnetic CoFe layers, which are relevant for spintronic applications.",2306.12233v2
+2004-04-29,Strongly-correlated crystal-field approach to 3d oxides - the orbital magnetism in 3d-ion compounds,"We have developed the crystal-field approach with strong electron
+correlations, extended to the Quantum Atomistic Solid-State theory (QUASST), as
+a physically relevant theoretical model for the description of electronic and
+magnetic properties of 3d-atom compounds. Its applicability has been
+illustrated for LaCoO3, FeBr2 and Na2V3O7. According to the QUASST theory in
+compounds containing open 3d-/4f-/5f-shell atoms the discrete atomic-like
+low-energy electronic structure survives also when the 3d atom becomes the full
+part of a solid matter. This low-energy atomic-like electronic structure, being
+determined by local crystal-field interactions and the intra-atomic spin-orbit
+coupling, predominantly determines electronic and magnetic properties of the
+whole compound.
+  We understand our theoretical research as a continuation of the Van Vleck's
+studies on the localized magnetism. We point out, however, the importance of
+the orbital magnetism and the intra-atomic spin-orbit coupling for the
+physically adequate description of real 3d-ion compounds and 3d magnetism. Our
+studies clearly indicate that it is the highest time to ''unquench'' the
+orbital moment in solid-state physics in description of 3d-atom containing
+compounds.
+  PACS No: 75.10.D; 71.70.E
+  Keywords: magnetism, transition-metal compounds, 3d magnetism, crystal field,
+spin-orbit coupling, orbital magnetism",0404713v1
+2012-10-16,Magnetic dichroism in angular resolved hard X-ray photoelectron spectroscopy from buried magnetic layers,"This work reports on the measurement of magnetic dichroism in
+angular-resolved photoelectron spectroscopy from in-plane magnetized buried
+thin films. The high bulk sensitivity of hard X-ray photoelectron spectroscopy
+(HAXPES) in combination with circularly polarized radiation enables the
+investigation of the magnetic properties of buried layers. Angular
+distributions of high kinetic energy (7 to 8 keV) photoelectrons in a range of
+about 60 deg were recorded in parallel to the energy distribution. Depending on
+purpose, energy and angular resolutions of 150 to 250 meV and 0.17 to 2 deg can
+be accomplished simultaneously in such experiments. Experiments were performed
+on exchange-biased magnetic layers covered by thin oxide films. More
+specifically, the angular distribution of photoelectrons from the ferromagnetic
+layer Co2FeAl layer grown on MnIr exchange-biasing layer was investigated where
+the magnetic structure is buried beneath a MgO layer. Pronounced magnetic
+dichroism is found in the Co and Fe 2p states for all angles of emission. A
+slightly increased magnetic dichroism was observed for normal emission in
+agreement with theoretical considerations.",1210.4374v1
+2013-10-22,Evidence for Multiferroic Characteristics in NdCrTiO5,"We report NdCrTiO5 to be an unusual multiferroic material with large magnetic
+field dependent electric polarization. While magneto-electric coupling in this
+two magnetic sub-lattice oxide is well established, the purpose of this study
+is to look for spontaneous symmetry breaking at the magnetic transition. The
+conclusions are based on extensive magnetization, dielectric and polarization
+measurements around its antiferromagnetic ordering temperature of 18K. Room
+temperature X-ray diffraction pattern of NdCrTiO5 reveals that the sample is
+single phase with an orthorhombic crystal structure that allows linear
+magneto-electric coupling. DC magnetization measurement shows magnetization
+downturn at 11K together with a small kink corresponding to the Co+3
+sub-lattice ordering at ~18K. An anomaly in dielectric constant is observed
+around the magnetic ordering temperature that increases substantially with
+increasing magnetic field. Through detailed pyroelectric current measurements
+at zero magnetic field, particularly as a function of thermal cycling, we
+establish that NdCrTiO5 is a genuine multiferroic material that is possibly
+driven by collinear magneto-striction.",1310.5803v1
+2017-04-10,Magnetic Transitions under Ultrahigh Magnetic Fields of up to 130 T in the Breathing Pyrochlore Antiferromagnet LiInCr4O8,"The magnetization processes of the spin-3/2 antiferromagnet LiInCr4O8
+comprising a ""breathing"" pyrochlore lattice, which is an alternating array of
+small and large tetrahedra, are studied under ultrahigh magnetic fields of up
+to 130 T using state-of-the-art pulsed magnets. A half magnetization plateau is
+observed above 90 T to 130 T, suggesting that LiInCr4O8 has a strong
+spin-lattice coupling, similar to conventional chromium spinel oxides. The
+magnetization of LiGa0.125In0.875Cr4O8, in which the structural and magnetic
+transitions at low temperatures have been completely suppressed, shows a sudden
+increase above 13 T, indicating that a spin gap of 2.2 meV exists between a
+tetramer singlet ground state and an excited state with total spin 1, with the
+latter being stabilized by the application of a magnetic field. The breathing
+pyrochlore antiferromagnet is found to be a unique frustrated system with
+strong spin-lattice coupling and bond alternation.",1704.02784v1
+2011-11-26,DC and AC Magnetization Study of Complex Ilmenite Oxides (Ni1-xCox)TiO3 (0.05 < x < 0.8),"Ilmenite solid-solutions, (Ni1-xCox)TiO3 (0.05 < x < 0.8), were synthesized
+at ambient atmosphere through solid-state reaction and were studied by energy
+dispersive spectroscopy of X-rays, X-ray diffraction, and DC and AC
+magnetometry. Temperature dependent DC magnetic measurements revealed two
+transitions. The first took place at around 27 K and the second at 63 K. The
+low-temperature phase was antiferromagnetic. The phase observed between 27 and
+63 K is characteristic to the solid-solution and is not found in either of the
+constituent members. A fit of the data to the Curie-Weiss law gave magnetic
+moment values which were significantly larger than the values based on the
+quenched orbital momentum assumption. Zero-field-cooled magnetization
+measurements with weak magnetic field revealed unexpected negative
+magnetization at low temperatures. Below 63 K the DC magnetization exhibited
+time dependent behavior. Frequency and magnetic field dependent AC
+magnetization is also addressed.",1111.6140v1
+2018-06-12,Emergent c-axis magnetic helix in manganite-nickelate superlattices,"The nature of the magnetic order in (La2/3Sr1/3MnO3)9/(LaNiO3)3 superlattices
+is investigated using x-ray resonant magnetic reflectometry. We observe a new
+c-axis magnetic helix state in the (LaNiO3)3 layers that had never been
+reported in nickelates, and which mediates the ~130deg magnetic coupling
+between the ferromagnetic (La2/3Sr1/3MnO3)9 layers, illustrating the power of
+x-rays for discovering the magnetic state of complex oxide interfaces. Resonant
+inelastic x-ray scattering and x-ray absorption spectroscopy show that Ni-O
+ligand hole states from bulk LaNiO3 are mostly filled due to interfacial
+electron transfer from Mn, driving the Ni orbitals closer to an atomic-like 3d8
+configuration. We discuss the constraints imposed by this electronic
+configuration to the microscopic origin of the observed magnetic structure. The
+presence of a magnetic helix in (La2/3Sr1/3MnO3)9/(LaNiO3)3 is crucial for
+modeling the potential spintronic functionality of this system and may be
+important for designing emergent magnetism in novel devices in general.",1806.04775v1
+2019-11-05,Foucault imaging and small-angle electron diffraction in controlled external magnetic fields,"We report a method for acquiring Foucault images and small-angle electron
+diffraction patterns in external magnetic fields using a conventional
+transmission electron microscope without any modification. In the electron
+optical system that we have constructed, external magnetic fields parallel to
+the optical axis can be controlled using the objective lens pole piece under
+weak excitation conditions in the Foucault mode and the diffraction mode. We
+observe two ferromagnetic perovskite-type manganese oxides,
+La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ and Nd$_{0.5}$Sr$_{0.5}$MnO$_{3}$, in order to
+visualize magnetic domains and their magnetic responses to external magnetic
+fields. In rhombohedral-structured La$_{0.7}$Sr$_{0.3}$MnO$_{3}$, pinning of
+magnetic domain walls at crystallographic twin boundaries was found to have a
+strong influence on the generation of new magnetic domains in external applied
+magnetic fields.",1911.01683v1
+2022-05-11,Violation of the Rule of Parsimony: Mixed Local Moment and Itinerant Fe Magnetism in Fe$_{3}$GeN,"Ternary iron nitrides are of considerable interest due to their diverse
+magnetic properties. We find, based on first principles calculations, that the
+relatively minor structural distortion from the cubic antiperovskite structure
+in Fe$_3$GeN leads to unusual magnetic behavior. In particular, there is a
+separation into Fe sites with very different magnetic behaviors, specifically a
+site with Fe atoms having a stable local moment and a site where the Fe shows
+characteristics of much more itinerant behavior. This shows a remarkable
+flexibility of the Fe magnetic behavior in these nitrides and points towards
+the possibility of systems where minor structural and chemical changes can lead
+to dramatic changes in magnetic properties. The results suggest that,
+analogously to oxide perovskite materials, modulation of magnetic properties
+via chemical or strain control of octahedral rotation may be feasible. This may
+then lead to approaches for tuning magnetism to realize properties of interest,
+for example tuning magnetic transitions to quantum critical regimes or to
+proximity to metamagnetic transitions of interest for devices.",2205.05506v2
+2006-08-08,Multi-vanadium substituted polyoxometalates as efficient electrocatalysts for the oxidation of l-cysteine at low potential on glassy carbon electrodes,"The electrochemical behaviours of the sandwich-type complex
+[As2W18(VO)3O66]11- were studied in a pH 7 medium and compared with those of
+the three following Dawson-type vanadium-substituted complexes: [P2V2W16O62]8-
+(P2V2W16), [P2MoV2W15O62]8- (P2MoV2W15) and [P2V3W15O62]9- (P2V3W15).
+Electrochemistry shows that the sandwich-type POM contains 2 VIV centers and
+one VV center and must be formulated As2V2IVVW18, in agreement with titration,
+elemental analysis and magnetic measurements on this element.. All the POMs of
+this work proved efficient for the oxidation of L-cysteine. Comparison of the
+present results with those of mono-Vanadium substituted POMs indicates that
+accumulation of vanadium atoms in the POM framework is beneficial in the
+electrocatalytic process. In addition, the present work highlights the
+important influence of the POM structure in the electrocatalytic oxidation of
+L-cysteine. The remarkable outcome of this work is that the potential for the
+oxidation of L-cysteine in the presence of the selected POMs has been
+substantially driven in the negative direction compared to the case of glassy
+carbon alone, a feature which is associated with faster kinetics. The stability
+of the systems must also be pointed out.",0608085v1
+2008-01-08,Quantum oscillations and the Fermi surface in an underdoped high-Tc superconductor,"Despite twenty years of research, the phase diagram of high transition-
+temperature superconductors remains enigmatic. A central issue is the origin of
+the differences in the physical properties of these copper oxides doped to
+opposite sides of the superconducting region. In the overdoped regime, the
+material behaves as a reasonably conventional metal, with a large Fermi
+surface. The underdoped regime, however, is highly anomalous and appears to
+have no coherent Fermi surface, but only disconnected ""Fermi arcs"". The
+fundamental question, then, is whether underdoped copper oxides have a Fermi
+surface, and if so, whether it is topologically different from that seen in the
+overdoped regime. Here we report the observation of quantum oscillations in the
+electrical resistance of the oxygen-ordered copper oxide YBa2Cu3O6.5,
+establishing the existence of a well-defined Fermi surface in the ground state
+of underdoped copper oxides, once superconductivity is suppressed by a magnetic
+field. The low oscillation frequency reveals a Fermi surface made of small
+pockets, in contrast to the large cylinder characteristic of the overdoped
+regime. Two possible interpretations are discussed: either a small pocket is
+part of the band structure specific to YBa2Cu3O6.5 or small pockets arise from
+a topological change at a critical point in the phase diagram. Our
+understanding of high-transition temperature (high-Tc) superconductors will
+depend critically on which of these two interpretations proves to be correct.",0801.1281v1
+2009-10-30,Resonant x-ray scattering in 3d-transition-metal oxides: Anisotropy and charge orderings,"The structural, magnetic and electronic properties of transition metal oxides
+reflect in atomic charge, spin and orbital degrees of freedom. Resonant x-ray
+scattering (RXS) allows us to perform an accurate investigation of all these
+electronic degrees. RXS combines high-Q resolution x-ray diffraction with the
+properties of the resonance providing information similar to that obtained by
+atomic spectroscopy (element selectivity and a large enhancement of scattering
+amplitude for this particular element and sensitivity to the symmetry of the
+electronic levels through the multipole electric transitions). Since electronic
+states are coupled to the local symmetry, RXS reveals the occurrence of
+symmetry breaking effects such as lattice distortions, onset of electronic
+orbital ordering or ordering of electronic charge distributions. We shall
+discuss the strength of RXS at the K absorption edge of 3d transition-metal
+oxides by describing various applications in the observation of local
+anisotropy and charge disproportionation. Examples of these resonant effects
+are (I) charge ordering transitions in manganites, Fe3O4 and ferrites and (II)
+forbidden reflections and anisotropy in Mn3+ perovskites, spinel ferrites and
+cobalt oxides. In all the studied cases, the electronic (charge and/or
+anisotropy) orderings are determined by the structural distortions.",0910.5789v1
+2017-08-29,Hybridization-controlled charge transfer and induced magnetism at correlated oxide interfaces,"At interfaces between conventional materials, band bending and alignment are
+classically controlled by differences in electrochemical potential. Applying
+this concept to oxides in which interfaces can be polar and cations may adopt a
+mixed valence has led to the discovery of novel two-dimensional states between
+simple band insulators such as LaAlO3 and SrTiO3. However, many oxides have a
+more complex electronic structure, with charge, orbital and/or spin orders
+arising from correlations between transition metal and oxygen ions. Strong
+correlations thus offer a rich playground to engineer functional interfaces but
+their compatibility with the classical band alignment picture remains an open
+question. Here we show that beyond differences in electron affinities and polar
+effects, a key parameter determining charge transfer at correlated oxide
+interfaces is the energy required to alter the covalence of the metaloxygen
+bond. Using the perovskite nickelate (RNiO3) family as a template, we probe
+charge reconstruction at interfaces with gadolinium titanate GdTiO3. X-ray
+absorption spectroscopy shows that the charge transfer is thwarted by
+hybridization effects tuned by the rare-earth (R) size. Charge transfer results
+in an induced ferromagnetic-like state in the nickelate, exemplifying the
+potential of correlated interfaces to design novel phases. Further, our work
+clarifies strategies to engineer two-dimensional systems through the control of
+both doping and covalence.",1708.08823v1
+2017-12-27,Controlled synthesis of the antiperovskite oxide superconductor Sr$_{3-x}$SnO,"A large variety of perovskite oxide superconductors are known, including some
+of the most prominent high-temperature and unconventional superconductors.
+However, superconductivity among the oxidation state inverted material class,
+the antiperovskite oxides, was reported just recently for the first time. In
+this superconductor, Sr$_{3-x}$SnO, the unconventional ionic state Sn$^{4-}$ is
+realized and possible unconventional superconductivity due to a band inversion
+has been discussed. Here, we discuss an improved facile synthesis method,
+making it possible to control the strontium deficiency in Sr$_{3-x}$SnO.
+Additionally, a synthesis method above the melting point of Sr$_{3}$SnO is
+presented. We show temperature dependence of magnetization and electrical
+resistivity for superconducting strontium deficient Sr$_{3-x}$SnO
+($T_{\mathrm{c}}$ ~ 5 K) and for Sr$_{3}$SnO without a superconducting
+transition down to 0.15 K. Further, we reveal a significant effect of strontium
+raw material purity on the superconductivity and achieve 40% increased
+superconducting volume fraction (~100%) compared to the highest value reported
+so far. More detailed characterisation utilising powder X-ray diffraction and
+energy-dispersive X-ray spectroscopy show that a minor cubic phase, previously
+suggested to be a Sr$_{3-x}$SnO, is SrO. The improved characterization and
+controlled synthesis reported herein enable detailed investigations on the
+superconducting nature and its dependency on the strontium deficiency in
+Sr$_{3-x}$SnO.",1712.09484v1
+2019-04-03,Pulsed Laser Deposition of Rocksalt Magnetic Binary Oxides,"Here we systematically explore the use of pulsed laser deposition technique
+(PLD) to grow three basic oxides that have rocksalt structure but different
+chemical stability in the ambient atmosphere: NiO (stable), MnO (metastable)
+and EuO (unstable). By tuning laser fluence, an epitaxial single-phase nickel
+oxide thin-film growth can be achieved in a wide range of temperatures from 10
+to 750 {\deg}C. At the lowest growth temperature, the out-of-plane strain
+raises to 1.5%, which is five times bigger than that in a NiO film grown at 750
+{\deg}C. MnO thin films that had long-range ordered were successfully deposited
+on the MgO substrates after appropriate tuning of deposition parameters. The
+growth of MnO phase was strongly influenced by substrate temperature and laser
+fluence. EuO films with satisfactory quality were deposited by PLD after oxygen
+availability had been minimized. Synthesis of EuO thin films at rather low
+growth temperature prevented thermally-driven lattice relaxation and allowed
+growth of strained films. Overall, PLD was a quick and reliable method to grow
+binary oxides with rocksalt structure in high quality that can satisfy
+requirements for applications and for basic research.",1904.01780v2
+2021-10-30,Atomic-scale 3D imaging of individual dopant atoms in a complex oxide,"A small percentage of dopant atoms can completely change the physical
+properties of the host material. For example, chemical doping controls the
+electronic transport behavior of semiconductors and gives rise to a wide range
+of emergent electric and magnetic phenomena in oxides. Imaging of individual
+dopant atoms in lightly doped systems, however, remains a major challenge,
+hindering characterization of the site-specific effects and local dopant
+concentrations that determine the atomic-scale physics. Here, we apply
+atom-probe tomography (APT) to resolve individual Ti atoms in the narrow band
+gap semiconductor ErMnO3 with a nominal proportion of 0.04 atomic percent. Our
+3D imaging measures the Ti concentration at the unit cell level, providing
+quantitative information about the dopant distribution within the ErMnO3
+crystal lattice. High-resolution APT maps reveal the 3D lattice position of
+individual Ti atoms, showing that they are located within the Mn layers with no
+signs of clustering or other chemical inhomogeneities. The 3D atomic-scale
+visualization of individual dopant atoms provides new opportunities for the
+study of local structure-property relations in complex oxides, representing an
+important step toward controlling dopant-driven quantum phenomena in
+next-generation oxide electronics.",2111.00317v1
+2022-09-26,Ionic modulation at the LaAlO$_3$/KTaO$_3$ interface for extreme high-mobility two-dimensional electron gas,"Due to the coexistence of many emergent phenomena, including 2D
+superconductivity and a large Rashba spin-orbit coupling, 5d transition metal
+oxides based two-dimensional electron systems (2DESs) have been prospected as
+one of the potential intrants for modern electronics. However, despite the
+lighter electron mass, the mobility of carriers, a key requisite for
+high-performance devices, in 5d-oxides devices remains far behind their
+3d-oxides analogs. The carriers mobility in these oxides is significantly
+hampered by the inevitable presence of defects generated during the growth
+process. Here, we report very high mobility ($\sim$ 22650
+cm$^2$V$^{-1}$s$^{-1}$) of 5d-2DES confined at the LaAlO$_3$/KTaO$_3$
+interface. The high mobility, which is beyond the values observed in
+LaAlO$_3$/SrTiO$_3$ and $\gamma$-Al$_2$O$_3$/SrTiO$_3$ systems in the same
+carrier-density range, is achieved using the ionic-liquid gating at room
+temperature. We postulate that the ionic-liquid gating affects the oxygen
+vacancies and efficiently reduces any disorder at the interface. Investigating
+density and mobility in a broad range of back-gate voltage, we reveal that the
+mobility follows the power-law $\mu \propto n^{1.2}$, indicating the very high
+quality of ionic-liquid-gated LaAlO$_3$/KTaO$_3$ devices, consistent with our
+postulate. Further, the analysis of the quantum oscillations measured in high
+magnetic fields confirms that the high-mobility electrons occupy the electronic
+sub-bands emerging from the Ta:5d orbitals of KTaO$_3$.",2209.12390v1
+2022-11-09,Charge ordering as the driving mechanism for superconductivity in rare-earth nickel oxides,"Superconductivity is one of the most intriguing properties of matter
+described by an attractive interaction that bounds electrons into Cooper pairs.
+To date, the highest critical temperature at ambient conditions is achieved in
+copper oxides. While layered nickel oxides were long proposed to be analogous
+to cuprates, superconductivity was only demonstrated in 2019 albeit without
+clarifying the pairing mechanism. Here we use Density Functional Theory (DFT)
+to show that superconductivity in nickelates is driven by an electron-phonon
+coupling originating from a charge ordering. Due to an intrinsic electronic
+instability in half-doped compounds, Ni$^{1.5+}$ cations dismutate into more
+stable Ni$^+$ and Ni$^{2+}$ cations, which is accompanied by a bond
+disproportionation of NiO$_4$ complexes producing an insulating charge ordered
+state. Once doping suppresses the instability, the bond disproportionation
+vibration is sufficient to reproduce the key characteristic of nickelates
+observed experimentally, notably the dome of T$_c$ as a function of doping
+content. These phenomena are identified if relevant degrees of freedom as well
+as an exchange correlation functional that sufficiently amends self-interaction
+errors are involved in the simulations. Finally, despite the presence of
+correlation effects inherent to $3d$ elements, nickelates superconductors
+appear similar to non-magnetic bismuth oxide superconductors.",2211.04870v2
+2022-11-16,Emergence of large spin-charge interconversion at an oxidized Cu/W interface,"Spin-orbitronic devices can integrate memory and logic by exploiting
+spin-charge interconversion (SCI), which is optimized by design and materials
+selection. In these devices, such as the magnetoelectric spin-orbit (MESO)
+logic, interfaces are crucial elements as they can prohibit or promote spin
+flow in a device as well as possess spin-orbit coupling resulting in
+interfacial SCI. Here, we study the origin of SCI in a Py/Cu/W lateral spin
+valve and quantify its efficiency. An exhaustive characterization of the
+interface between Cu and W electrodes uncovers the presence of an oxidized
+layer (WO$_x$). We determine that the SCI occurs at the Cu/WO$_x$ interface
+with a temperature-independent interfacial spin-loss conductance of $G_{||}
+\approx$ 20 $\times$ 10$^{13} \Omega^{-1}m^{-2}$ and an interfacial spin-charge
+conductivity $\sigma_{SC}=-$1610 $\Omega^{-1}cm^{-1}$ at 10 K ($-$830
+$\Omega^{-1}cm^{-1}$ at 300 K). This corresponds to an efficiency given by the
+inverse Edelstein length $\lambda_{IEE}=-$0.76 nm at 10 K ($-$0.4 nm at 300 K),
+which is remarkably larger than in metal/metal and metal/oxide interfaces and
+bulk heavy metals. The large SCI efficiency at such an oxidized interface is a
+promising candidate for the magnetic readout in MESO logic devices.",2211.09250v1
+2002-07-03,Magnetic enhancement of Co$_{0.2}$Zn$_{0.8}$Fe$_2$O$_4$ spinel oxide by mechanical milling,"We report the magnetic properties of mechanically milled
+Co$_{0.2}$Zn$_{0.8}$Fe$_2$O$_4$ spinel oxide. After 24 hours milling of the
+bulk sample, the XRD spectra show nanostructure with average particle size
+$\approx$ 20 nm. The as milled sample shows an enhancement in magnetization and
+ordering temperature compared to the bulk sample. If the as milled sample is
+annealed at different temperatures for the same duration, recrystallization
+process occurs and approaches to the bulk structure on increasing the annealing
+temperatures. The magnetization of the annealed samples first increases and
+then decreases. At higher annealing temperature ($\sim$ 1000$^{0}$C) the system
+shows two coexisting magnetic phases {\it i.e.}, spin glass state and
+ferrimagnetic state, similar to the as prepared bulk sample. The room
+temperature M\""{o}ssbauer spectra of the as milled sample, annealed at
+300$^{0}$C for different durations (upto 575 hours), suggest that the observed
+change in magnetic behaviour is strongly related with cations redistribution
+between tetrahedral (A) and octahedral (O) sites in the spinel structure. Apart
+from the cation redistribution, we suggest that the enhancement of
+magnetization and ordering temperature is related with the reduction of B site
+spin canting and increase of strain induced anisotropic energy during
+mechanical milling.",0207095v1
+2020-07-19,A geometric approach to separate the effects of magnetic susceptibility and chemical shift/exchange in a phantom with isotropic magnetic susceptibility,"Purpose: To separate the effects of magnetic susceptibility and chemical
+shift/exchange in a phantom with isotropic magnetic susceptibility. To generate
+a chemical shift/exchange-corrected quantitative susceptibility mapping (QSM)
+result.
+  Theory and Methods: Magnetic susceptibility and chemical shift/exchange are
+the properties of a material. Both are known to induce the resonance frequency
+shift in MRI. In current QSM, the susceptibility is reconstructed from the
+frequency shift, ignoring the contribution of the chemical shift/exchange. In
+this work, a simple geometric approach, which averages the frequency shift maps
+from three orthogonal B0 directions to generate a chemical shift/exchange map,
+is developed using the fact that the average nullifies the (isotropic)
+susceptibility effects. The resulting chemical shift/exchange map is subtracted
+from the total frequency shift, producing a frequency shift map solely from
+susceptibility. Finally, this frequency shift map is reconstructed to a
+susceptibility map using a QSM algorithm. The proposed method is validated in
+numerical simulations and applied to phantom experiments with olive oil, bovine
+serum albumin, ferritin, and iron oxide solutions.
+  Results: Both simulations and experiments confirm that the method
+successfully separates the contributions of the susceptibility and chemical
+shift/exchange, reporting the susceptibility and chemical shift/exchange of
+olive oil (susceptibility: 0.62 ppm, chemical shift: -3.60 ppm), bovine serum
+albumin (susceptibility: -0.059 ppm, chemical shift: 0.008 ppm), ferritin
+(susceptibility: 0.125 ppm, chemical shift: -0.005 ppm), and iron oxide
+(susceptibility: 0.30 ppm, chemical shift: -0.039 ppm) solutions.
+  Conclusion: The proposed method successfully separates the susceptibility and
+chemical shift/exchange in phantoms with isotropic magnetic susceptibility.",2007.09614v1
+2009-12-01,"Electronic structure, magnetic and dielectric properties of the edge-sharing copper-oxide chain compound NaCu$_{2}$O$_{2}$","We report an experimental study of \nco, a Mott insulator containing chains
+of edge-sharing CuO$_4$ plaquettes, by polarized x-ray absorption spectroscopy
+(XAS), resonant magnetic x-ray scattering (RMXS), magnetic susceptibility, and
+pyroelectric current measurements. The XAS data show that the valence holes
+reside exclusively on the Cu$^{2+}$ sites within the copper-oxide spin chains
+and populate a $d$-orbital polarized within the CuO$_4$ plaquettes. The RMXS
+measurements confirm the presence of incommensurate magnetic order below a
+N\'eel temperature of $T_N = 11.5$ K, which was previously inferred from
+neutron powder diffraction and nuclear magnetic resonance data. In conjunction
+with the magnetic susceptibility and XAS data, they also demonstrate a new
+""orbital"" selection rule for RMXS that is of general relevance for magnetic
+structure determinations by this technique. Dielectric property measurements
+reveal the absence of significant ferroelectric polarization below $T_N$, which
+is in striking contrast to corresponding observations on the isostructural
+compound \lco. The results are discussed in the context of current theories of
+multiferroicity.",0912.0168v1
+2012-04-19,Ferromagnetism in graphene nanoribbons: split versus oxidative unzipped ribbons,"Two types of graphene nanoribbons: (a) potassium-split graphene nanoribbons
+(GNRs), and (b) oxidative unzipped and chemically converted graphene
+nanoribbons (CCGNRs) were investigated for their magnetic properties using the
+combination of static magnetization and electron spin resonance measurements.
+The two types of ribbons possess remarkably different magnetic properties.
+While the low temperature ferromagnet-like feature is observed in both types of
+ribbons, such room temperature feature persists only in potassium-split
+ribbons. The GNRs show negative exchange bias, but the CCGNRs exhibit a
+'positive exchange bias'. Electron spin resonance measurements infer that the
+carbon related defects may responsible for the observed magnetic behaviour in
+both types of ribbons. Furthermore, proton hyperfine coupling strength has been
+obtained from hyperfine sublevel correlation experiments performed on the GNRs.
+Electron spin resonance provides no indications for the presence of potassium
+(cluster) related signals, emphasizing the intrinsic magnetic nature of the
+ribbons. Our combined experimental results may infer the coexistence of
+ferromagnetic clusters with anti-ferromagnetic regions leading to disordered
+magnetic phase. We discuss the origin of the observed contrast in the magnetic
+behaviours of these two types of ribbons.",1204.4401v1
+2019-06-03,An XMCD study of magnetism and valence state in iron-substituted strontium titanate,"Room temperature ferromagnetism was characterized for thin films of
+SrTi$_{0.6}$Fe$_{0.4}$O$_{3-{\delta}}$ grown by pulsed laser deposition on
+SrTiO$_{3}$ and Si substrates under different oxygen pressures and after
+annealing under oxygen and vacuum conditions. X-ray magnetic circular dichroism
+demonstrated that the magnetization originated from Fe$^{2+}$ cations, whereas
+Fe$^{3+}$ and Ti$^{4+}$ did not contribute. Films with the highest magnetic
+moment (0.8 {\mu}B per Fe) had the highest measured Fe$^{2+}$:Fe${^3+}$ ratio
+of 0.1 corresponding to the largest concentration of oxygen vacancies ({\delta}
+= 0.19). Post-growth annealing treatments under oxidizing and reducing
+conditions demonstrated quenching and partial recovery of magnetism
+respectively, and a change in Fe valence states. The study elucidates the
+microscopic origin of magnetism in highly Fe-substituted
+SrTi$_{1-x}$Fe$_x$O$_{3-{\delta}}$ perovskite oxides and demonstrates that the
+magnetic moment, which correlates with the relative content of Fe$^{2+}$ and
+Fe$^{3+}$, can be controlled via the oxygen content, either during growth or by
+post-growth annealing.",1906.00509v1
+2004-01-30,Quantum Magnetic Excitations from Stripes in Copper-Oxide Superconductors,"In the copper-oxide parent compounds of the high-transition-temperature
+superconductors, the valence electrons are localized, one per copper site, due
+to strong intraatomic Coulomb repulsion. A symptom of the localization is
+antiferromagnetism, where the spins of localized electrons alternate between up
+and down. The superconductivity appears when mobile 'holes' are doped into this
+insulating state, and it coexists with antiferromagnetic fluctuations. In one
+approach to the coexistence, the holes are believed to self-organize into
+'stripes' that alternate with antiferromagnetic (insulating) regions within
+copper-oxide planes. Such an unusual electronic state would necessitate an
+unconventional mechanism of superconductivity. There is an apparent problem
+with this picture, however: measurements of magnetic excitations in
+superconducting YBa(2)Cu(3)O(6+x) near optimum doping are incompatible with the
+naive expectations for a material with stripes. Here we report neutron
+scattering measurements on stripe-ordered La(1.875)Ba(0.125)CuO(4). We show
+that the measured excitations are, surprisingly, quite similar to those in
+YBa(2)Cu(3)O(6+x) (i.e., the predicted spectrum of magnetic excitations is
+wrong). We find instead that the observed spectrum can be understood within a
+stripe model by taking account of quantum excitations. Our results support the
+concept that stripe correlations are essential to high-transition-temperature
+superconductivity.",0401621v2
+2012-11-27,"Structural Phase Transitions of the Metal Oxide Perovskites SrTiO3, LaAlO3 and LaTiO3 Studied with a Screened Hybrid Functional","We have investigated the structural phase transitions of the transition metal
+oxide perovskites SrTiO$_{3}$, LaAlO$_{3}$ and LaTiO$_{3}$ using the screened
+hybrid density functional of Heyd, Scuseria and Ernzerhof (HSE06). We show that
+HSE06-computed lattice parameters, octahedral tilts and rotations, as well as
+electronic properties, are significantly improved over semilocal functionals.
+We predict the crystal field splitting ($\Delta_{CF}$) resulting from the
+structural phase transition in SrTiO$_{3}$ and LaAlO$_{3}$ to be 3 meV and 10
+meV, respectively, in excellent agreement with experimental results. HSE06
+identifies correctly LaTiO$_{3}$ in the magnetic sates as a Mott insulator.
+Also, it predicts that the GdFeO$_{3}$-type distortion in non-magnetic
+LaTiO$_{3}$ will induce a large $\Delta_{CF}$ of 410 meV. This large
+crystal-field splitting associated with the large magnetic moment found in the
+G-type antiferromagnetic state suggest that LaTiO$_{3}$ has an induced orbital
+order, which is confirmed by the visualisation of the highest occupied
+orbitals. These results strongly indicate that HSE06 is capable of efficiently
+and accurately modeling perovskite oxides, and promises to efficiently capture
+the physics at their heterointerfaces.",1211.6371v1
+2016-09-14,Magnetoexcitons in cuprous oxide,"Two of the most striking experimental findings when investigating exciton
+spectra in cuprous oxide using high-resolution spectroscopy are the
+observability and the fine structure splitting of $F$ excitons reported by J.
+Thewes et al. [Phys. Rev. Lett. 115, 027402 (2015)]. These findings show that
+it is indispensable to account for the complex valence band structure and the
+cubic symmetry of the solid in the theory of excitons. This is all the more
+important for magnetoexcitons, where the external magnetic field reduces the
+symmetry of the system even further. We present the theory of excitons in
+$\mathrm{Cu_{2}O}$ in an external magnetic field and especially discuss the
+dependence of the spectra on the direction of the external magnetic field,
+which cannot be understood from a simple hydrogen-like model. Using
+high-resolution spectroscopy, we also present the corresponding experimental
+spectra for cuprous oxide in Faraday configuration. The theoretical results and
+experimental spectra are in excellent agreement as regards not only the
+energies but also the relative oscillator strengths. Furthermore, this
+comparison allows for the determination of the fourth Luttinger parameter
+$\kappa$ of this semiconductor.",1609.04275v3
+2016-10-26,Doping of Ga in antiferromagnetic semiconductor alpha-Cr2O3oxide and its effects on modified magnetic and electronic properties,"The samples of Ga doped Cr2O3 oxide have been prepared using chemical
+co-precipitation route. X-ray diffraction pattern and Raman spectra have
+confirmed rhombohedral crystal structure with space group R3-C. Magnetic
+measurement has indicated the dilution of antiferromagnetic (AFM) spin order in
+Ga doped alpha-Cr2O3 system oxide, where the AFM transition temperature of bulk
+alpha-Cr2O3 oxide at about 320 K has been suppressed and ferrimagnetic behavior
+is observed from the analysis of the temperature dependence of magnetization
+data below 350 K. Apart from Ga doping effect, the spin freezing (50 K-70 K)
+and superparamagnetic behavior of the surface spins at lower temperatures,
+typically below 50 K, have been exhibited due to nano-sized grains of the
+samples. All the samples showed non-linear current-voltage (I-V)
+characteristics. However, I-V characteristics of the Ga doped samples are
+remarkably different from alpha-Cr2O3 sample. The I-V curves of Ga doped
+samples have exhibited many unique electronic properties, e.g., bi-stable (low
+resistance- LR and high resistance-HR) electronic states and negative
+differential resistance (NDR). Optical absorption spectra revealed three
+electronic transitions in the samples associated with band gap energy at about
+2.67-2.81 eV, 1.91-2.11 eV, 1.28-1.35 eV, respectively.",1610.08426v1
+2017-01-26,Magnetic and electronic properties of La$_3M$O$_7$ and possible polaron formation in hole-doped La$_3M$O$_7$ ($M$=Ru and Os),"Oxides with $4d$/$5d$ transition metal ions are physically interesting for
+their particular crystalline structures as well as the spin-orbit coupled
+electronic structures. Recent experiments revealed a series of $4d$/$5d$
+transition metal oxides $R_3M$O$_7$ ($R$: rare earth; $M$: $4d$/$5d$ transition
+metal) with unique quasi-one-dimensional $M$ chains. Here first-principles
+calculations have been performed to study the electronic structures of
+La$_3$OsO$_7$ and La$_3$RuO$_7$. Our study confirm both of them to be Mott
+insulating antiferromagnets with identical magnetic order. The reduced magnetic
+moments, which are much smaller than the expected value for ideal high-spin
+state ($3$ $t_{2g}$ orbitals occupied), are attributed to the strong $p-d$
+hybridization with oxygen ions, instead of the spin-orbit coupling. The
+Ca-doping to La$_3$OsO$_7$ and La$_3$RuO$_7$ can not only modulate the nominal
+carrier density but also affect the orbital order as well as the local
+distortions. The Coulombic attraction and particular orbital order would prefer
+to form polarons, which might explain the puzzling insulating behavior of doped
+$5d$ transition metal oxides. In addition, our calculation predict that the
+Ca-doping can trigger ferromagnetism in La$_3$RuO$_7$ but not in La$_3$OsO$_7$.",1701.07655v1
+2019-11-17,Soft X-ray Absorption Spectroscopy and Magnetic Circular Dichroism as Operando Probes of Complex Oxide Electrolyte Gate Transistors,"Electrolyte-based transistors utilizing ionic liquids/gels have been highly
+successful in the study of charge-density-controlled phenomena, particularly in
+oxides. Experimental probes beyond transport have played a significant role,
+despite challenges to their application in electric double-layer transistors.
+Here, we demonstrate application of synchrotron soft X-ray absorption
+spectroscopy (XAS) and X-ray magnetic circular dichroism (XMCD) as operando
+probes of the charge state and magnetism in ion-gel-gated ferromagnetic
+perovskite films. Electrochemical response via oxygen vacancies at positive
+gate bias in LaAlO$_3$(001)/La$_{0.5}$Sr$_{0.5}$CoO$_{3-{\delta}}$ is used as a
+test case. XAS/XMCD measurements of 4-25 unit-cell-thick films first probe the
+evolution of hole doping (from the O K-edge pre-peak) and ferromagnetism (at
+the Co L-edges), to establish a baseline. Operando soft XAS/XMCD of
+electrolyte-gated films is then demonstrated, using optimized spin-coated gels
+with thickness $\sim$1 ${\mu}$m, and specific composition. Application of gate
+voltages up to +4 V is shown to dramatically suppress the O $K$-edge XAS
+pre-peak intensity and Co $L$-edge XMCD, thus enabling the Co valence and
+ferromagnetism to be tracked upon gate-induced reduction. Soft XAS and XMCD,
+with appropriate electrolyte design, are thus established as viable for the
+operando characterization of electrolyte-gated oxides.",1911.07139v1
+2021-03-18,An antisite defect mechanism for room temperature ferroelectricity in orthoferrites,"Single-phase multiferroic materials that allow the coexistence of
+ferroelectric and magnetic ordering above room temperature are highly
+desirable, motivating an ongoing search for mechanisms for unconventional
+ferroelectricity in magnetic oxides. Here, we report an antisite defect
+mechanism for room temperature ferroelectricity in epitaxial thin films of
+yttrium orthoferrite, YFeO3, a perovskite-structured canted antiferromagnet. A
+combination of piezoresponse force microscopy, atomically resolved elemental
+mapping with aberration corrected scanning transmission electron microscopy and
+density functional theory calculations reveals that the presence of YFe
+antisite defects facilitates a non-centrosymmetric distortion promoting
+ferroelectricity. This mechanism is predicted to work analogously for other
+rare earth orthoferrites, with a dependence of the polarization on the radius
+of the rare earth cation. Furthermore, a vertically aligned nanocomposite
+consisting of pillars of a magnetoelastic oxide CoFe2O4 embedded epitaxially in
+the YFeO3 matrix exhibits both robust ferroelectricity and ferrimagnetism at
+room temperature, as well as a noticeable strain-mediated magnetoelectric
+coupling effect. Our work uncovers the distinctive role of antisite defects in
+providing a novel mechanism for ferroelectricity in a range of magnetic
+orthoferrites and further augments the functionality of this family of complex
+oxides for multiferroic applications.",2103.10338v1
+2023-11-15,Orbital degree of freedom in high entropy oxides,"The spin, charge, and lattice degrees of freedom and their interplay in high
+entropy oxides were intensively investigated in recent years. However, how the
+orbital degree of freedom is affected by the extreme disorder in high entropy
+oxides hasn't been studied. In this work, using perovskite structured
+\textit{R}VO$_3$ as a materials playground, we report how the disorder arising
+from mixing different rare earth ions at the rare earth site affects the
+orbital ordering of V$^{3+}$ t$_{2g}$-electrons. Since each member of
+\textit{R}VO$_3$ crystallizes into the same orthorhombic \textit{Pbnm}
+structure, the configurational entropy should not be critical for the success
+synthesis of (\textit{R}$_1$,...,\textit{R}$_n$)VO$_3$. The spin and orbital
+ordering was studied by measuring magnetic properties and specific heat of
+single crystals. Rather than the number and type of rare earth ions, the
+average ionic radius and size variance are the key factors determining the spin
+and orbital order in (\textit{R}$_1$,...,\textit{R}$_n$)VO$_3$. When the size
+variance is small, the average ionic radius takes precedence in dictating spin
+and orbital order. Increasing size variance suppresses the G-type orbital order
+and C-type magnetic order but favors the C-OO/G-AF state and the spin-orbital
+entanglement. These findings suggest that the extreme disorder introduced by
+mixing multiple rare earth ions in high entropy perovskites might be employed
+to preserve the orbital degree of freedom to near the magnetic ordering
+temperature, which is necessary for the electronic driven orbital ordering in a
+Kugel-Khomskii compound.",2311.09087v2
+2024-03-30,Ferromagnetic state with large magnetic moments realized in epitaxially strained Sr3Ru2O7 films,"Technical advancement of oxide molecular beam epitaxy (MBE) has opened new
+avenues for studying various quantum transport phenomena in correlated
+transition-metal oxides, as exemplified by the exotic superconductivity of
+Sr$_2$RuO$_4$ and quantum oscillations of SrRuO$_3$. On the other hand, film
+research of another Ruddlesden-Popper strontium ruthenate Sr$_3$Ru$_2$O$_7$
+which exhibits a unique quantum phase related to metamagnetism in bulk systems
+did not progress well. Here we report the fabrication of high-quality
+Sr$_3$Ru$_2$O$_7$ thin films by oxide MBE and the observation of a
+strain-induced ferromagnetic ground state. The change in magnetic exchange
+coupling evaluated by first-principles calculations indicates a systematic
+relation between the compression of the $c$-axis length and induced
+ferromagnetism. Giant epitaxial strain in high-quality films will be a key to a
+comprehensive understanding of the magnetism in Ruddlesden-Popper strontium
+ruthenates Sr$_{n+1}$Ru$_n$O$_{3n+1}$, which sensitively depends on the ratio
+of in-plane to out-of-plane Ru-Ru distances.",2404.00214v1
+2008-08-27,Magnetic phase evolution in the spinel compounds Zn$_{1-x}$Co$_x$Cr$_2$O$_4$,"We present the magnetic properties of complete solid solutions of
+ZnCr$_2$O$_4$ and CoCr$_2$O$_4$: two well-studied oxide spinels with very
+different magnetic ground states. ZnCr$_2$O$_4$, with non-magnetic $d^{10}$
+cations occupying the A site and magnetic $d^3$ cations on the B site, is a
+highly frustrated antiferromagnet. CoCr$_2$O$_4$, with magnetic $d^7$ cations
+(three unpaired electrons) on the A site as well, exhibits both N\'eel
+ferrimagnetism as well as commensurate and incommensurate non-collinear
+magnetic order. More recently, CoCr$_2$O$_4$ has been studied extensively for
+its polar behavior which arises from conical magnetic ordering. Gradually
+introducing magnetism on the A site of ZnCr$_2$O$_4$ results in a transition
+from frustrated antiferromagnetism to glassy magnetism at low concentrations of
+Co, and eventually to ferrimagnetic and conical ground states at higher
+concentrations. Real-space Monte-Carlo simulations of the magnetic
+susceptibility suggest that the first magnetic ordering transition and features
+of the susceptibility across $x$ are captured by near-neighbor self- and
+cross-couplings between the magnetic A and B atoms. We present as a part of
+this study, a method for displaying the temperature dependence of magnetic
+susceptibility in a manner which helps distinguish between compounds possessing
+purely antiferromagnetic interactions from compounds where other kinds of
+ordering are present.",0808.3789v3
+2024-01-24,Magnetic nanoparticles: from the nanostructure to the physical properties,"Some of the synthesis methods and physical properties of iron-oxide based
+magnetic nanoparticles such as Fe3-xO4 and CoxFe3-xO4 are reviewed because of
+their interest in health, environmental applications, and ultra-high-density
+magnetic recording. Unlike high crystalline quality nanoparticles larger than a
+few nanometers that show bulk-like magnetic and electronic properties,
+nanostructures with increasing structural defects yield a progressive worsening
+of their general performance due to frozen magnetic disorder and local breaking
+of their crystalline symmetry. Thus, it is shown that single-crystal,
+monophasic nanoparticles do not exhibit significant surface or finite-size
+effects, such as spin canting, reduced saturation magnetization, high closure
+magnetic fields, hysteresis-loop shift or dead magnetic layer features which
+are mostly associated with crystallographic defective systems. Besides, the key
+role of the nanoparticle coating, surface anisotropy, and inter-particle
+interactions are discussed. Finally, the results of some single particle
+techniques -- magnetic force microscopy, X-ray photoemission electron
+microscopy, and electron magnetic chiral dichroism -- that allow studying
+individual nanoparticles down to sub-nanometer resolution with element, valence
+and magnetic selectivity, are presented. All in all, the intimate, fundamental
+correlation of the nanostructure (crystalline, chemical, magnetic) to the
+physical properties of the nanoparticles is ascertained.",2401.13422v1
+2004-04-07,Absence of room temperature ferromagnetism in bulk Mn-doped ZnO,"Structural and magnetic properties have been studied for polycrystalline
+Zn_1-xMn_xO (x=0.02, 0.03, 0.05). Low-temperature (~500 oC) synthesis leaves
+unreacted starting ZnO and manganese oxides. Contrary to a recent report, no
+bulk ferromagnetism was observed for single-phase materials synthesized in air
+at temperatures above 900 oC. Single-phase samples show paramagnetic
+Curie-Weiss behavior.",0404186v1
+2004-08-19,Magnetic Susceptibility of NiO Nanoparticles,"Nickel oxide nanoparticles of different sizes are prepared and characterized
+by x-ray diffraction and transmission electron microscopy. A.C. susceptibility
+measurements as a function of temperature are carried out for various particle
+sizes and frequencies. We find that the behavior of the system is spin glass
+like.",0408427v1
+2008-01-20,The Kondo effect of surface excitons,"A recombination radiation line of real excitons in dense two-dimensional
+electron gas at the [100] silicon surface is observed in luminescence spectra
+of metal-oxide-semiconductor (MOS) structures. A new effect of anisotropic
+paramagnetic reduction of the luminescence line indicates a strong influence of
+the Kondo correlations on electron paramagnetism of the excitons.",0801.3055v1
+2014-05-13,Magneto-electric operators in neutron scattering,"We succeed in deriving an exact expression for the magnetic interaction of
+neutrons and electrons including magneto-electric operators, allowed in the
+absence of a centre of inversion symmetry. Central characters are a spin
+anapole and an orbital (toroidal) analogue, in addition to familiar parity-even
+operators. A simulation of neutron diffraction by antiferromagnetic copper
+oxide makes full use of information inferred from a thorough investigation with
+resonant x-ray Bragg diffraction.",1405.3060v1
+2020-08-13,On the detection of surface spin freezing in iron oxide nanoparticles and its long-term evolution under ambient oxidation,"Exchange bias effects linked to surface spin freezing (SSF) are commonly
+found in iron oxide nanoparticles, while signatures of SSF in low-field
+temperature-dependent magnetization curves have been much less frequently
+reported. Here, we present magnetic properties of dense assemblies of
+similar-sized (~ 8 nm diameter) particles synthesized by a magnetite (sample
+S1) and a maghemite (sample S2) method, and the influence of long-term (4-year)
+sample aging under ambient conditions on these properties. The size of the
+exchange bias field of the different sample (fresh or aged) states is found to
+correlate with (a) whether a low-temperature hump feature signaling the SSF
+transition is detected in out-of-phase ac susceptibility or zero-field-cooled
+(ZFC) dc magnetization recorded at low field and with (b) the prominence of
+irreversibility between FC and ZFC curves recorded at high field. Sample S1
+displays a lower magnetization than S2, and it is in S1 where the largest SSF
+effects are found. These effects are significantly weakened by aging but remain
+larger than the SSF effects in S2, where the influence of aging is considerably
+smaller. A non-saturating component due to spin disorder in S1 also weakens
+with aging, accompanied by, we infer, an increase in the superspin and the
+radius of the ordered nanoparticle cores. X-ray diffraction and M\""ossbauer
+spectroscopy provide indication of maghemite-like stoichiometry in both aged
+samples as well as thicker disordered particle shells in aged-S1 relative to
+aged-S2 (crystallographically-disordered and spin-disordered according to
+diffraction and M\""ossbauer, respectively). The pronounced diminution in SSF
+effects with aging in S1 is attributed to a (long-term) transition, caused by
+ambient oxidation, from magnetite-like to maghemite-like stoichiometry, and a
+concomitant softening of the spin-disordered shell anisotropy...",2008.05874v1
+1999-07-27,Cooperative Jahn-Teller Effect on the Magnetic Structure of Manganese Oxides,"The magnetic structure of LaMnO$_3$ is investigated on three-dimensional
+clusters of MnO$_6$ octahedra by using a combination of relaxation and Monte
+Carlo techniques. It is found that the cooperative Jahn-Teller phonons lead to
+the stabilization of A-type antiferromagnetic and C-type orbital structures in
+the physically relevant region of parameter space for LaMnO$_3$ with small
+corrections due to tilting effects. The results suggest that strong Coulomb
+interactions are not necessary for a qualitative description of undoped
+manganites. In fact, it is shown that the present result is not essentially
+changed even if the Coulomb interaction is explicitly included.",9907430v1
+2003-10-27,A spin metal-oxide-semiconductor field-effect transistor using half-metallic-ferromagnet contacts for the source and drain,"We propose and theoretically analyze a novel metal-oxide-semiconductor
+field-effect-transistor (MOSFET) type of spin transistor (hereafter referred to
+as a spin MOSFET) consisting of a MOS gate structure and
+half-metallic-ferromagnet (HMF) contacts for the source and drain. When the
+magnetization configuration between the HMF source and drain is parallel
+(antiparallel), highly spin-polarized carriers injected from the HMF source to
+the channel are transported into (blocked by) the HMF drain, resulting in the
+magnetization-configuration-dependent output characteristics. Our
+two-dimensional numerical analysis indicates that the spin MOSFET exhibits high
+(low) current drive capability in the parallel (antiparallel) magnetization,
+and that extremely large magnetocurrent ratios can be obtained. Furthermore,
+the spin MOSFET satisfies other important requirements for ""spintronic""
+integrated circuits, such as high amplification capability, low power-delay
+product, and low off-current.",0310623v1
+2004-02-13,Superconducting Properties under Magnetic Field in Na$_{0.35}$CoO$_{2}{\cdot}1.3$H$_{2}$O Single Crystal,"We report the in-plane resistivity and magnetic susceptibility of the layered
+cobalt oxide Na$_{0.35}$CoO$_{2}{\cdot}1.3$H$_{2}$O single crystal. The
+temperature dependence of the resistivity shows metallic behavior from room
+temperature to the superconducting transition temperature $T_{c}$ of 4.5 K.
+Sharp resistive transition, zero resistivity and almost perfect superconducting
+volume fraction below $T_{c}$ indicate the good quality and the bulk
+superconductivity of the single crystal. The upper critical field $H_{c2}$ and
+the coherence length $\xi$ are obtained from the resistive transitions in
+magnetic field parallel to the c-axis and the $ab$-plane. The anisotropy of
+$\xi$, $\xi_{ab} / \xi_{c} =$ 12 nm/1.3 nm $\simeq$ 9.2, suggests that this
+material is considered to be an anisotropic three dimensional superconductor.
+In the field parallel to the $ab$-plane, $H_{c2}$ seems to be suppressed to the
+value of Pauli paramagnetic limit. It may indicate the spin singlet
+superconductivity in the cobalt oxide.",0402355v1
+2005-05-10,Percolative Ferromagnetism in Anatase Co:TiO2,"We revisit the most widely investigated and controversial oxide diluted
+magnetic semiconductor (DMS), Co:TiO2, with a new high temperature film growth,
+and show that the corresponding material is not only an intrinsic DMS
+ferromagnet, but also supports a percolative mechanism of ferromagnetism. We
+establish the uniformity of dopant distribution across the film cross section
+by Z-contrast imaging via scanning transmission electron microscopy (STEM) and
+electron energy loss spectroscopy (EELS) at spatial resolution of 0.4 nm and
+the oxidized 2+ valence state of cobalt by x-ray absorption spectroscopy (XAS).
+The dependence of magnetic properties on cobalt concentration is consistent
+with the defect polaron percolation model. The peculiar increase in the
+transport activation energy above a specific cobalt concentration further
+emphasizes the polaron contribution to magnetic order.",0505265v1
+2005-08-11,"Co-doped (La,Sr)TiO3-d: a high-Curie temperature diluted magnetic system with large spin-polarization","We report on tunneling magnetoresistance (TMR) experiments that demonstrate
+the existence of a significant spin polarization in Co-doped (La,Sr)TiO3-d
+(Co-LSTO), a ferromagnetic diluted magnetic oxide system (DMOS) with high Curie
+temperature. These TMR experiments have been performed on magnetic tunnel
+junctions associating Co-LSTO and Co electrodes. Extensive structural analysis
+of Co-LSTO combining high-resolution transmission electron microscopy and Auger
+electron spectroscopy excluded the presence of Co clusters in the Co-LSTO layer
+and thus, the measured ferromagnetism and high spin polarization are intrinsic
+properties of this DMOS. Our results argue for the DMOS approach with complex
+oxide materials in spintronics.",0508289v1
+2005-12-14,Anomalous Magnetic and Thermal Behavior in Some RMn2O5 Oxides,"The RMn2O5 (R=Pr, Nd, Sm, and Eu) oxides showing magnetoelectric (ME)
+behavior have been prepared in polycrystalline form by a standard citrate
+route. The lattice parameters, obtained from the powder XRD analysis, follow
+the rare-earth contraction indicating the trivalent character of the R ions.
+Cusp-like anomalies in the magnetic susceptibility curve and sharp peaks in the
+specific heat were reported at the corresponding temperatures in RMn2O5 (R=Pr,
+Nd, Sm, and Eu) indicating the magnetic or electric ordering transitions.",0512293v1
+2006-12-07,Metal-ligand interplay in strongly-correlated oxides: a parametrized phase diagram for pressure induced spin transitions,"We investigate the magnetic properties of archetypal transition-metal oxides
+MnO, FeO, CoO and NiO under very high pressure by x-ray emission spectroscopy
+at the K\beta line. We observe a strong modification of the magnetism in the
+megabar range in all the samples except NiO. The results are analyzed within a
+multiplet approach including charge-transfer effects. The pressure dependence
+of the emission line is well accounted for by changes of the ligand field
+acting on the d electrons and allows us to extract parameters like local
+d-hybridization strength, O-2p bandwidth and ionic crystal field across the
+magnetic transition. This approach allows a first-hand insight into the
+mechanism of the pressure induced spin transition.",0612179v1
+2008-02-08,Magnetodielectric coupling in a triangular Ising lattice,"Dielectric constant measurement under magnetic field is an efficient
+technique to study the coupling between charges and spins in insulating
+materials. For magnetic oxides, the geometric frustration is known to be a key
+ingredient to observe such a coupling. Measurements for the triangular
+Ising-like cobaltite Ca3Co2O6 have been made. Single crystals of Ca3Co2O6 are
+found to exhibit a magnetodielectric effect below TN=25K with a peak in the
+e(H) curve at the ferri to ferromagnetic transition. This relation between e
+and magnetization has been modelized by using two order parameters in an energy
+expansion derived from the Landau formalism and the fluctuation-dissipation
+theorem. This result emphasizes the great potential of insulating transition
+metal oxides for the search of magnetodielectric effect.",0802.1136v1
+2008-04-07,CaCrO3: an anomalous antiferromagnetic metallic oxide,"Combining infrared reflectivity, transport, susceptibility and several
+diffraction techniques, we find compelling evidence that CaCrO3 is a rare case
+of a metallic and antiferromagnetic transition-metal oxide with a
+three-dimensional electronic structure. LSDA calculations correctly describe
+the metallic behavior as well as the anisotropic magnetic ordering pattern of C
+type: The high Cr valence state induces via sizeable pd hybridization
+remarkably strong next-nearest neighbor interactions stabilizing this ordering.
+The subtle balance of magnetic interactions gives rise to magneto-elastic
+coupling, explaining pronounced structural anomalies observed at the magnetic
+ordering transition.",0804.1071v1
+2008-08-18,Magnetic and charge transport properties of the Na-based Os oxide pyrochlore,"Na-based osmium oxide pyrochlore was synthesized for the first time by an
+ion-exchange method. KOs2O6 was used as a host compound. Elelectron probe
+micro-analysis, synchrotron x-ray diffraction analysis, and thermo-gravimetric
+analysis confirmed its structure not as the beta-type but as the defect-type
+pyrochlore. The composition was identified as Na1.4Os2O6.H2O. Electrical
+resistivity, heat capacity, and magnetization measurements of the
+polycrystalline Na1.4Os2O6.H2O clarified absence of superconductivity above 2
+K, being in contrast to what were found for the beta-pyrochlore AOs2O6 (A = Cs,
+Rb, K). Sommerfeld coefficient of 22 mJ K-2 mol-1 of Na1.4Os2O6.H2O was
+smallest among those of AOs2O6. A magnetic anomaly at ~57 K and possible
+associated magnetoresistance (+3.7 % at 2 K in 70 kOe) were found.",0808.2331v1
+2008-12-15,"Synthesis and structure of new pyrochlore-type oxides Ln2ScNbO7 (Ln = Pr, Nd, Eu, Gd, Dy)","We report the synthesis and structural study of mixed oxides in the Ln2ScNbO7
+series. New phases with Ln = Pr, Eu, Gd and Dy are obtained. All crystallize in
+the cubic pyrochlore structure type, space group F-d3m, with no Sc-Nb ordering
+on the B-site. The structures are determined by Rietveld refinement. The
+evolution of cell parameters, interatomic distances and angles as a function of
+lanthanide cation size is discussed. Magnetic measurements show the absence of
+ordering down to 2 K, in agreement with the presence of strong geometric
+frustration in the lanthanide sublattice. The europium phase shows a peculiar
+magnetic behaviour; its magnetic susceptibility becomes constant below ca 50 K.
+This feature confirms the behaviour observed previously on Eu2Ti2O7 and is
+ascribed to crystal field effects.",0812.2758v1
+2010-07-09,From quantum criticality to enhanced thermopower in strongly correlated layered cobalt oxide,"We report on susceptibility measurements in the strongly correlated layered
+cobalt oxide [BiBa0.66K0.36O2]CoO2, which demonstrate the existence of a
+magnetic quantum critical point (QCP) governing the electronic properties. The
+investigated low frequency susceptibility displays a scaling behavior with both
+the temperature T and the magnetic field B ranging from the high-T non-Fermi
+liquid down to the low-T Fermi liquid. Whereas the inferred scaling form can be
+discussed within the standard framework of the quantum critical phenomena, the
+determined critical exponents suggest an unconventional magnetic QCP of a
+potentially generic type. Accordingly, these quantum critical fluctuations
+account for the anomalous logarithmic temperature dependence of the
+thermopower. This result allows us to conjecture that quantum criticality can
+be an efficient source of enhanced thermopower.",1007.1606v1
+2010-08-15,Charge and orbital order in transition metal oxides,"A short introduction to the complex phenomena encountered in transition metal
+oxides with either charge or orbital or joint charge-and-orbital order, usually
+accompanied by magnetic order, is presented. It is argued that all the types of
+above ordered phases in these systems follow from strong Coulomb interactions
+as a result of certain compromise between competing instabilities towards
+various types of magnetic order and optimize the gain of kinetic energy in
+doped systems. This competition provides a natural explanation of the stripe
+order observed in doped cuprates, nickelates and manganites. In the undoped
+correlated insulators with orbital degrees of freedom the orbital order
+stabilizes particular types of anisotropic magnetic phases, and we contrast the
+case of decoupled spin and orbital degrees of freedom in the manganites with
+entangled spin-orbital states which decide about certain rather exotic
+phenomena observed in the perovskite vanadates at finite temperature. Examples
+of successful concepts in the theoretical approaches to these complex systems
+are given and some open problems of current interest are indicated.",1008.2515v1
+2010-10-26,Rods of Neutron Scattering Intensity in Yb2Ti2O7: Compelling Evidence for Significant Anisotropic Exchange in a Magnetic Pyrochlore Oxide,"Paramagnetic correlations in the magnetic material Yb2Ti2O7 have been
+investigated via neutron scattering, revealing a [111] rod of scattering
+intensity. Assuming interactions between the Yb^{3+} ions composed of all
+symmetry-allowed nearest neighbor exchange interactions and long-range dipolar
+interactions, we construct a model Hamiltonian that allows for an excellent
+description of the neutron scattering data. Our results provide compelling
+evidence for significant anisotropic exchange interactions in an insulating
+magnetic pyrochlore oxide. We also compute the real space correlations leading
+to the [111] rod of scattering.",1010.5476v2
+2011-01-22,Unconventional Multiferroicity in Cupric Oxide,"The magnetic phase transitions reported below 230 K in cupric oxide are
+analyzed theoretically at the macroscopic and microscopic levels. The
+incommensurate multiferroic and lock-in commensurate phases are shown to
+realize an inverted sequence of symmetry-breaking mechanisms with respect to
+the usual sequence occurring in low temperature multiferroic compounds. The
+higher temperature spin-spiral phase results from coupled order-parameters
+which decouple at the lock-in transition to the commensurate ground state
+phase. Expressing the order-parameters in function of the magnetic spins allows
+determining the symmetries and magnetic structures of the equilibrium phases
+and the microscopic interactions which give rise to the polarization.",1101.4284v1
+2012-12-18,Magnetoelasticity in ACr2O4 spinel oxides,"Dynamical properties of the lattice structure was studied by optical
+spectroscopy in ACr2O4 chromium spinel oxide magnetic semiconductors over a
+broad temperature region of T=10-335K. The systematic change of the A-site ions
+(A=Mn, Fe, Co, Ni and Cu) showed that the occupancy of 3d orbitals on the
+A-site, has strong impact on the lattice dynamics. For compounds with orbital
+degeneracy (FeCr2O4, NiCr2O4 and CuCr2O4), clear splitting of infrared-active
+phonon modes and/or activation of silent vibrational modes have been observed
+upon the Jahn-Teller transition and at the onset of the subsequent long-range
+magnetic order. Although MnCr2O4 and CoCr2O4 show multiferroic and
+magnetoelectric character, no considerable magnetoelasticity was found in
+spinel compounds without orbital degeneracy as they closely preserve the
+high-temperature cubic spinel structure even in their magnetic ground state.
+Besides lattice vibrations, intra-atomic 3d-3d transitions of the A$^{2+}$ ions
+were also investigated to determine the crystal field and Racah parameters and
+the strength of the spin-orbit coupling.",1212.4301v1
+2013-03-29,Formation of double ring patterns on Co2MnSi Heusler alloy thin film by anodic oxidation under scanning probe microscope,"Double ring formation on Co2MnSi (CMS) films is observed at electrical
+breakdown voltage during local anodic oxidation (LAO) using atomic force
+microscope (AFM). Corona effect and segregation of cobalt in the vicinity of
+the rings is studied using magnetic force microscopy and energy dispersive
+spectroscopy. Double ring forma-tion is attributed to the interaction of
+ablated material with the induced magnetic field during LAO. Steepness of
+forward bias transport characteristics from the unperturbed region of the CMS
+film suggest a non equilibrium spin contribution. Such mesoscopic textures in
+magnetic films by AFM tip can be potentially used for memory storage
+applications.",1303.7470v2
+2014-08-14,Effect of Diffused Hydrogen on the Conductance of Fe/Mgo/Fe Magnetic Tunnel Junctions: Atomistic Simulation,"In this work we have analysed the deterimental effect on conductance caused
+by diffusion of hydrogen atoms in interstitial voids during fabrication process
+of magnesium oxide barrier of an Fe MgO Fe magnetic tunnel junction, using
+first principle calculations. This diffusion of hydrogen atoms in interstitial
+voids in barrier disturbs a certain kind of symmetry possessed by magnesium
+oxide often termed as delta 1 state symmetry. Distortion in delta 1 state
+symmetry tempers the condutance through the magnetic tunnel junction specially
+in parallel configuration, which in turn reduces the Tunnelling Magneto
+Resistance TMR to large extent. Improved methods of fabrication can be used to
+counter such kind of problems which affect device operation.",1408.3199v1
+2014-09-10,Torque magnetometry of an amorphous-alumina/strontium-titanate interface,"We report torque magnetometry measurements of an oxide heterostructure
+consisting of an amorphous Al$_2$O$_3$ thin film grown on a crystalline
+SrTiO$_3$ substrate ($a$-AO/STO) by atomic layer deposition. We find a torque
+response that resembles previous studies of crystalline LaAlO$_3$/SrTiO$_3$
+(LAO/STO) heterointerfaces, consistent with strongly anisotropic magnetic
+ordering in the plane of the interface. Unlike crystalline LAO, amorphous
+Al$_2$O$_3$ is nonpolar, indicating that planar magnetism at an oxide interface
+is possible without the strong internal electric fields generated within the
+polarization catastrophe model. We discuss our results in the context of
+current theoretical efforts to explain magnetism in crystalline LAO/STO.",1409.3194v4
+2015-03-08,Antiferromagnetic order and spin dynamics in iron-based superconductors,"High-transition temperature (high-$T_c$) superconductivity in the iron
+pnictides/chalcogenides emerges from the suppression of the static
+antiferromagnetic order in their parent compounds, similar to copper oxides
+superconductors. This raises a fundamental question concerning the role of
+magnetism in the superconductivity of these materials. Neutron scattering, a
+powerful probe to study the magnetic order and spin dynamics, plays an
+essential role in determining the relationship between magnetism and
+superconductivity in high-$T_c$ superconductors. The rapid development of
+modern neutron time-of-flight spectrometers allows a direct determination of
+the spin dynamical properties of iron-based superconductors throughout the
+entire Brillouin zone. In this review, we present an overview of the neutron
+scattering results on iron-based superconductors, focusing on the evolution of
+spin excitation spectra as a function of electron/hole-doping and isoelectronic
+substitution. We compare spin dynamical properties of iron-based
+superconductors with those of copper oxide and heavy fermion superconductors,
+and discuss the common features of spin excitations in these three families of
+unconventional superconductors and their relationship with superconductivity.",1503.02340v2
+2015-05-20,"Orbital Arrangements and Magnetic Interactions in the Quasi-One-Dimensional Cuprates ACuMoO_4(OH) (A = Na, K)","A new spin-1/2 quasi-one-dimensional antiferromagnet KCuMoO_4(OH) is prepared
+by the hydrothermal method. The crystal structures of KCuMoO_4(OH) and the
+already-known Na-analogue, NaCuMoO_4(OH), are isotypic, comprising chains of
+Cu^{2+} ions in edge-sharing CuO_4(OH)_2 octahedra. Despite the structural
+similarity, their magnetic properties are quite different because of the
+different arrangements of d_{x2-y2} orbitals carrying spins. For NaCuMoO_4(OH),
+d_{x2-y2} orbitals are linked by superexchange couplings via two bridging oxide
+ions, which gives a ferromagnetic nearest-neighbor interaction J_1 of -51 K and
+an antiferromagnetic next-nearest-neighbor interaction J_2 of 36 K in the
+chain. In contrast, a staggered d_{x2-y2} orbital arrangement in KCuMoO_4(OH)
+results in superexchange couplings via only one bridging oxide ion, which makes
+J_1 antiferromagnetic as large as 238 K and J_2 negligible. This comparison
+between the two isotypic compounds demonstrates an important role of orbital
+arrangements in determining the magnetic properties of cuprates.",1505.05332v1
+2015-05-27,Selective Interface Control of Order Parameters in Complex Oxides,"In complex materials observed electronic phases and transitions between them
+often involves coupling between many degrees of freedom whose entanglement
+convolutes understanding of the instigating mechanism. Metal-insulator
+transitions are one such problem where coupling to the structural, orbital,
+charge, and magnetic order parameters frequently obscures the underlying
+physics. Here, we demonstrate a way to unravel this conundrum by
+heterostructuring a prototypical multi-ordered complex oxide NdNiO3 in ultra
+thin geometry, which preserves the metal-to-insulator transition and bulk-like
+magnetic order parameter, but entirely suppresses the symmetry lowering and
+charge order parameter. These findings illustrate the utility of
+heterointerfaces as a powerful method for removing competing order parameters
+to gain greater insight into the nature of the transition, here revealing that
+the magnetic order generates the transition independently, leading to a purely
+electronic Mott metal-insulator transition.",1505.07451v4
+2015-07-15,Modulated Helical Metals at Magnetic Domain Walls of Pyrochlore Iridium Oxides,"Spontaneous symmetry breakings, metal-insulator transitions, and transport
+properties of magnetic-domain-wall states in pyrochlore iridium oxides are
+studied by employing a symmetry adapted effective hamiltonian with a slab
+perpendicular to the (111) direction of the pyrochlore lattice. Emergent
+metallic domain wall, which has unconventional topological nature with a
+controllable and mobile metallic layer, is shown to host Fermi surfaces with
+modulated helical spin textures resembling Rashba metals. The helical nature of
+the domain-wall Fermi surfaces is experimentally detectable by anomalous Hall
+conductivity, circular dichroism, and optical Hall conductivity under external
+magnetic fields. Possible applications of the domain-wall metals to
+spin-current generation and ""half-metallic"" conduction are also discussed.",1507.04153v1
+2015-07-22,Fragile charge order in the non-superconducting ground state of the underdoped high temperature superconductors,"The normal state in the hole underdoped copper oxide superconductors has
+proven to be a source of mystery for decades. The measurement of a small Fermi
+surface by quantum oscillations on suppression of superconductivity by high
+applied magnetic fields, together with complementary spectroscopic measurements
+in the hole underdoped copper oxide superconductors, point to a nodal electron
+pocket from charge order in YBa2Cu3O6+x. Here we report quantum oscillation
+measurements in the closely related stoichiometric material YBa2Cu4O8, which
+reveal similar Fermi surface properties to YBa2Cu3O6+x, despite an absence of
+charge order signatures in the same spectroscopic techniques such as x-ray
+diffraction that revealed signatures of charge order in YBa2Cu3O6+x. Fermi
+surface reconstruction in YBa2Cu4O8 is suggested to occur from magnetic field
+enhancement of charge order that is rendered fragile in zero magnetic fields
+because of its potential unconventional symmetry, and/or its occurrence as a
+subsidiary to more robust underlying electronic correlations.",1507.06109v1
+2015-10-11,The ferroelectric polarization of Y2CoMnO6 aligns along the b-axis: the first-principles calculations,"Double-perovskite A2BB'O6 oxides with magnetic B and B' ions and E*-type
+antiferromagnetic order (E*-AFM, i.e. the ++-- structure) are believed to
+exhibit promising multiferroic properties, and Y2CoMnO6 (YCMO) is one candidate
+in this category. However, the microscopic origins for magnetically induced
+ferroelectricity in YCMO remain unclear. In this work, we perform detailed
+symmetry analysis on the exchange striction effect and lattice distortion, plus
+the first-principles calculations on YCMO. The E*-AFM state as the ground state
+with other competing states such as ferromagnetic and A-antiferromagnetic
+orders is confirmed. It is revealed that the ferroelectricity is generated by
+the exchange striction associated with the E*-AFM order and chemically rdered
+Mn/Co occupation. Both the lattice symmetry consideration and first-principles
+calculations predict that the electric polarization aligns along the b-axis.
+The calculated polarization reaches up to 0.4682 uC/cm2, mainly from the ionic
+displacement contribution. The present work presents a comprehensive
+understanding of the multiferroic mechanisms in YCMO and is of general
+significance for predicting emergent multiferroicity in other double-perovskite
+magnetic oxides.",1510.03039v1
+2015-11-15,Oxidation and magnetic states of chalcopyrite CuFeS$_{2}$: a first principles calculation,"The ground state band structure, magnetic moments, charges and population
+numbers of electronic shells of Cu and Fe atoms have been calculated for
+chalcopyrite CuFeS2 using density functional theory. The comparison between our
+calculation results and experimental data (X-ray photoemission, X-ray
+absorption and neutron diffraction spectroscopy) has been made. Our
+calculations predict a formal oxidation state for chalcopyrite as
+Cu$^{1+}$Fe$^{3+}$S$_{2}$$^{2-}$. However, the assignment of formal valence
+state to transition metal atoms appears to be oversimplified. It is anticipated
+that the valence state can be confirmed experimentally by nuclear magnetic and
+nuclear quadrupole resonance and M\""ossbauer spectroscopy methods.",1511.04753v1
+2016-09-09,On the origin of perpendicular magnetic anisotropy in strained Fe-Co(-X) films,"Very high magnetic anisotropies have been theoretically predicted for
+strained Fe-Co(-X) and indeed several experiments on epitaxial thin films
+seemed to confirm strain induced anisotropy enhancement. This study presents a
+critical analysis of the different contributions to perpendicular anisotropy:
+volume, interface and surface anisotropies. Tracing these contributions,
+thickness series of single layer films as well as multilayers with Au-Cu
+buffers/interlayers of different lattice parameters have been prepared. The
+analysis of their magnetic anisotropy reveals a negligible influence of the
+lattice parameter of the buffer. Electronic effects, originating from both, the
+Au-Cu interface and the film surface, outrange the elastic effects. Surface
+anisotropy, however, exceeds the interface anisotropy by more than a factor of
+three. A comparison with results from Density Functional Theory suggests, that
+the experimentally observed strong perpendicular surface anisotropy originates
+from a deviation from an ideal oxide-free surface. Accordingly, tailored
+Fe-Co-X/oxide interfaces may open a route towards high anisotropy in rare-earth
+free materials.",1609.02903v2
+2017-08-26,Magneto-thermopower in the Weak Ferromagnetic Oxide CaRu0.8Sc0.2O3: An Experimental Test for the Kelvin Formula in a Magnetic Material,"We have measured the resistivity, the thermopower, and the specific heat of
+the weak ferromagnetic oxide CaRu0.8Sc0.2O3 in external magnetic fields up to
+140 kOe below 80 K. We have observed that the thermopower Q is significantly
+suppressed by magnetic fields at around the ferromagnetic transition
+temperature of 30 K, and have further found that the magneto-thermopower
+{\Delta}Q(H, T) = Q(H, T) - Q(0, T) is roughly proportional to the
+magneto-entropy {\Delta}S(H, T) = S(H, T)-S(0, T).We discuss this relationship
+between the two quantities in terms of the Kelvin formula, and find that the
+observed {\Delta}Q is quantitatively consistent with the values expected from
+the Kelvin formula, a possible physical meaning of which is discussed.",1708.07992v1
+2020-07-24,Reversible vs. irreversible voltage manipulation of interfacial magnetic anisotropy in Pt/Co/oxide multilayers,"The perpendicular magnetic anisotropy at the Co/oxide interface in Pt/Co/MOx
+(MOx = MgOx, AlOx, TbOx) was modified by an electric field using a 10 nm-thick
+ZrO2 as a solid electrolyte. The large voltage-driven modification of
+interfacial magnetic anisotropy and the non-volatility of the effect is
+explained in terms of the migration of oxygen ions towards/away from the Co/MOx
+interface. While the effect is reversible in Pt/Co/AlOx and Pt/Co/TbOx, where
+the Co layer can be oxidised or reduced, in Pt/Co/MgOx the effect has been
+found to be irreversible. We propose that these differences may be related to
+the different nature of the ionic conduction within the MOx layers.",2007.12570v1
+2014-03-13,Hyper-honeycomb iridate $β$-Li2IrO3 as a platform for Kitaev magnetism,"The realization of Kitaev spin liquid, where spins on a honeycomb lattice are
+coupled ferromagnetically by bond-dependent anisotropic interactions, has been
+a sought-after dream. 5d iridium oxides $\alpha$-Li2IrO3 and $\alpha$-Na2IrO3
+with a honeycomb lattice of Jeff = 1/2 moments recently emerged as a possible
+materialization. Strong signature of Kitaev physics, however, was not captured.
+Here we report the discovery of a complex iridium oxide $\beta$-Li2IrO3 with
+Jeff = 1/2 moments on ""hyper-honeycomb"" lattice, a three-dimensional analogue
+of honeycomb lattice. A positive Curie-Weiss temperature $\theta_{CW}$ ~ 40 K
+indicated dominant ferromagnetic interactions among Jeff = 1/2 moments in
+$\beta$-Li2IrO3. A magnetic ordering with a small entropy change was observed
+at Tc = 38 K, which, with the application of magnetic field of only 3 T,
+changed to a fully polarized state of Jeff = 1/2 moments. Those results imply
+that hyper-honeycomb beta-Li2IrO3 is located in the vicinity to a Kitaev spin
+liquid.",1403.3296v1
+2016-08-08,"Spin-glass behavior and pyroelectric anomalies in a new lithium-based oxide, Li3FeRuO5","The results of dc and ac magnetization, heat-capacity, 57Fe Moessbauer
+spectroscopy, dielectric, pyroelectric current and isothermal
+magneto-capacitance measurements on a recently reported lithium-based oxide,
+Li3FeRuO6, related to LiCoO2-type rhombohedral structure (space group, R-3m)
+are presented. The results reveal that the compound undergoes spin-glass
+freezing below 15 K. There is a peak around 34 K in pyroelectric data, which
+can not be attributed to ferroelectricity, but to the phenomenon of thermally
+stimulated depolarization current. As revealed by magnetocapacitance data above
+and below magnetic ordering temperature, magnetic and electric dipoles appear
+to be coupled, thereby offering evidence for magnetodielectric coupling.",1608.02304v1
+2019-10-30,Rydberg excitons in electric and magnetic fields obtained with the complex-coordinate-rotation method,"The complete theoretical description of experimentally observed
+magnetoexcitons in cuprous oxide has been achieved by F. Schweiner et al [Phys.
+Rev. B 95, 035202 (2017)], using a complete basis set and taking into account
+the valence band structure and the cubic symmetry of the solid. Here, we extend
+these calculations by investigating numerically the autoionising resonances of
+cuprous oxide in electric fields and in parallel electric and magnetic fields
+oriented in [001] direction. To this aim we apply the
+complex-coordinate-rotation method. Complex resonance energies are computed by
+solving a non-Hermitian generalised eigenvalue problem, and absorption spectra
+are simulated by using relative oscillator strengths. The method allows us to
+investigate the influence of different electric and magnetic field strengths on
+the position, the lifetime, and the shape of resonances.",1910.13941v1
+2017-05-18,Enhanced Ferromagnetism in Lacey Reduced Graphene Oxide Nano-ribbon,"Incorporation of magnetism in graphene based compounds holds great promise
+for potential spintronic applications. By optimizing point defects and high
+edge density of defects, we report many-fold increase in the ferromagnetic
+saturation moment in lacey reduced graphene oxide nanoribbons (LRGONR) as
+compared to other graphene derivatives. The samples were synthesized using
+chemical unzipping methodology. Detailed structural and morphological
+characterizations are discussed that include XRD, Raman, SEM, HRTEM and XPS
+measurements. Brilluoin function analysis to magnetization data reflects best
+fit for J = 7/2 with a saturation moment of 1.1 emu/g. The microscopic origin
+of magnetization in LRGONR is assigned to high edge defect density which has
+also been correlated to microstructure.",1705.06531v1
+2017-05-30,Magnetic and nematic orders of the 2DEG at oxide (111) surfaces and interfaces,"Recent experiments have explored two-dimensional electron gases (2DEGs) at
+oxide (111) surfaces and interfaces, finding evidence for hexagonal symmetry
+breaking in SrTiO$_3$ at low temperature. We discuss many-body instabilities of
+such (111) 2DEGs, incorporating multiorbital interactions in the $t_{2g}$
+manifold which can induce diverse magnetic and orbital orders. Such broken
+symmetries may partly account for the observed nematicity, cooperating or
+competing with phonon mechanisms. We present an effective field theory for the
+interplay of magnetism and nematic charge order, and discuss implications of
+the nematicity for transport and superconductivity in (111) 2DEGs.",1705.10795v3
+2019-01-27,The distribution of oxygen at the Ni81Fe19/Ta interface,"The knowledge of how oxygen atoms are distributed at a magnetic-metal /
+oxide, or magnetic-metal / non-magnetic-metal interface, can be an useful tool
+to optimize device production. Multilayered Ni81Fe19 / Ta samples consisting of
+15 bilayers of 2.5 nm each, grown onto glass substrates by magnetron sputtering
+from Ni81Fe19 and Ta targets, have been investigated. X-ray absorption near
+edge structure, extended X-Ray absorption fine structure, small angle X-ray
+diffraction, and simulations, were used to characterize the samples. Oxygen
+atoms incorporated onto Ni81Fe19 films during O2 exposition are mainly bonded
+to Fe atoms. This partial oxidation of the Ni81Fe19 surface works as a barrier
+to arriving Ta atoms, preventing intermixing at the Ni81Fe19 / Ta interface.
+The reduction of the Ni81Fe19 surface by the formation of TaO x is observed.",1901.09368v1
+2019-04-23,Offset fields in perpendicularly magnetized tunnel junctions,"We study the offset fields affecting the free layer of perpendicularly
+magnetized tunnel junctions. In extended films, the free layer offset field
+results from interlayer exchange coupling with the reference layer through the
+MgO tunnel oxide. The free layer offset field is thus accompanied with a shift
+of the free layer and reference layer ferromagnetic resonance frequencies. The
+shifts depend on the mutual orientation of the two magnetizations. The offset
+field decreases with the resistance area product of the tunnel oxide.
+Patterning the tunnel junction into an STT-MRAM disk-shaped cell changes
+substantially the offset field, as the reduction of the lateral dimension comes
+with the generation of stray fields by the reference and the hard layer. The
+experimental offset field compares best with the spatial average of the sum of
+these stray fields, thereby providing guidelines for the offset field
+engineering.",1904.10170v1
+2019-11-13,Perpendicular Magnetic Anisotropy in Conducting NiCo2O4 Films from Spin-Lattice Coupling,"High perpendicular magnetic anisotropy (PMA), a property needed for nanoscale
+spintronic applications, is rare in oxide conductors. We report the observation
+of a PMA up to 0.23 MJ/m3 in modestly strained epitaxial NiCo2O4 (NCO) films
+which are room-temperature ferrimagnetic conductors. Spin-lattice coupling
+manifested as magnetoelastic effect was found as the origin of the PMA. The
+in-plane xx-yy states of Co on tetrahedral sites play crucial role in the
+magnetic anisotropy and spin-lattice coupling with an energy scale of 1
+meV/f.u. The elucidation of the microscopic origin paves a way for engineering
+oxide conductors for PMA using metal/oxygen hybridizations.",1911.05322v1
+2020-11-02,Simulating Spin Waves in Entropy Stabilized Oxides,"The entropy stabilized oxide
+Mg$_{0.2}$Co$_{0.2}$Ni$_{0.2}$Cu$_{0.2}$Zn$_{0.2}$O exhibits antiferromagnetic
+order and magnetic excitations, as revealed by recent neutron scattering
+experiments. This observation raises the question of the nature of spin wave
+excitations in such disordered systems. Here, we investigate theoretically the
+magnetic ground state and the spin-wave excitations using linear spin-wave
+theory in combination with the supercell approximation to take into account the
+extreme disorder in this magnetic system. We find that the experimentally
+observed antiferromagnetic structure can be stabilized by a rhombohedral
+distortion together with large second nearest neighbor interactions. Our
+calculations show that the spin-wave spectrum consists of a well-defined
+low-energy coherent spectrum in the background of an incoherent continuum that
+extends to higher energies.",2011.01288v1
+2021-09-23,Giant magnetostriction and nonsaturating electric polarization up to 60 T in the polar magnet CaBaCo4O7,"Giant magnetostriction in insulating magnetic materials is highly required
+for applications but is rarely observed. Here we show that giant
+magnetostriction (> 1500 ppm) can be achieved in an insulating transition metal
+oxide CaBaCo4O7 where the ferrimagnetic ordering at TC ~ 62 K is associated
+with a huge change in the lattice. Moreover, because this material is
+pyroelectric with a non-switchable electric polarization (P), the giant
+magnetostriction results in a record-breaking magnetoelectric effect - a
+gigantic change of electric polarization (deltaP ~ 1.6 {\mu}C/cm2) in response
+to the applied magnetic field up to 60 T. Geometric frustration as well as the
+orbital instability of Co2+/Co3+ ions is believed to play a crucial role in the
+giant magnetostriction. Our study provides new insights on how to achieve both
+giant magnetostriction and pronounced magnetoelectric effect in insulating
+transition metal oxides.",2109.11149v1
+2021-12-13,Induction of Large Magnetic Anisotropy Energy and Formation of Multiple Dirac States in SrIrO$_3$ Films: Role of correlation and spin-orbit coupling,"The 5$d$ transition metal oxides, in particular iridates, host novel
+electronic and magnetic phases due to the interplay between onsite Coulomb
+repulsion ($U$) and spin-orbit coupling (SOC). The reduced dimensionality
+brings another degree of freedom to increase the functionality of these
+systems. By taking the example of ultrathin films of SrIrO$_3$,theoretically,
+we demonstrate that confinement led localization can introduce large magnetic
+anisotropy energy (MAE) in the range 2-7 meV/Ir which is one to two orders
+higher than that of the traditional MAE compounds formed out of transition
+metals and their multilayers. Furthermore, in the weak correlation limit,
+tailored terminations can yield multiple Dirac states across a large energy
+window of 2 eV around the Fermi energy which is a rare phenomena in correlated
+oxides and upon experimental realization it will give rise to unique transport
+properties with excitation and doping.",2112.06813v2
+2023-01-04,Atomic-scale Modulation of Synthetic Magnetic Order in Oxide Superlattices,"Atomic-scale precision control of magnetic interactions facilitates a
+synthetic spin order useful for spintronics, including advanced memory and
+quantum logic devices. Conventional modulation of synthetic spin order has been
+limited to metallic heterostructures that exploit RKKY interaction through a
+nonmagnetic metallic spacer; however, they face problems arising from Joule
+heating and/or electric breakdown. The practical realization and observation of
+a synthetic spin order across a nonmagnetic insulating spacer would lead to the
+development of spin-related devices with a completely different concept.
+Herein, we report the atomic-scale modulation of the synthetic spiral spin
+order in oxide superlattices composed of ferromagnetic metal and nonmagnetic
+insulator layers. The atomically controlled superlattice exhibit an oscillatory
+magnetic behavior, representing the existence of a spiral spin structure.
+Depth-sensitive polarized neutron reflectometry evidences modulated spiral spin
+structures as a function of the nonmagnetic insulator layer thickness.
+Atomic-scale customization of the spin state could lead the field one step
+further to actual spintronic applications.",2301.01403v1
+2023-06-30,Orbital-selective altermagnetism and correlation-enhanced spin-splitting in transition metal oxides,"We investigate the altermagnetic properties of strongly-correlated transition
+metal oxides considering the family of the quasi two-dimensional A2BO4 and
+three-dimensional ABO3. As a test study, we analyze the Mott insulators Ca2RuO4
+and YVO3. In both cases, the orbital physics is extremely relevant in the t2g
+subsector with the presence of an orbital-selective Mott physics in the first
+case and of a robust orbital-order in the second case. Using first-principles
+calculations, we show the presence of an orbital-selective altermagnetism in
+the case of Ca2RuO4. In the case of YVO3, we study the altermagnetism as a
+function of the magnetic ordering and of the Coulomb repulsion U. We find that
+the altermagnetism is present in all magnetic orders with the symmetries of the
+Brillouin zone depending on the magnetic order. Finally, the Coulomb repulsion
+enhances the non-relativistic spin-splitting making the strongly-correlated
+systems an exciting playground for the study of the altermagnetism.",2306.17497v1
+2023-07-31,Persistent spin dynamics in magnetically ordered honeycomb cobalt oxides,"In the quest to find quantum spin liquids, layered cobalt oxides Na2Co2TeO6
+and Na3Co2SbO6 have been proposed as promising candidates for approximating the
+Kitaev honeycomb model. Yet, their suitability has been thrown into question
+due to observed long-range magnetic order at low temperatures and indications
+of easy-plane, rather than Kitaev-type, spin anisotropy. Here we use muon spin
+relaxation to reveal an unexpected picture: contrary to the anticipated static
+nature of the long-range order, the systems show prevalent spin dynamics with
+spatially uneven distribution and varied correlation times. This underlines
+that the magnetic ground states cannot be solely described by the long-range
+order, suggesting a significant role of quantum fluctuations. Our findings not
+only shed new light on the complex physics of these systems but also underscore
+the need for a refined approach in the search for realizable quantum spin
+liquids.",2307.16451v1
+2024-01-22,The origin of magnetism in a supposedly nonmagnetic osmium oxide,"A supposedly nonmagnetic 5d$^1$ double perosvkite oxide is investigated by a
+combination of spectroscopic and theoretical methods, namely resonant inelastic
+X-ray scattering, X-ray absorption spectroscopy, magnetic circular dichroism,
+and multiplet ligand field calculations. We found that the large spin-orbit
+coupling admixes the 5d $t_{2g}$ and $e_g$ orbitals, covalency raises the 5d
+population well above the nominal value, and the local symmetry is lower than
+$O_h$. The obtained electronic interactions account for the finite magnetic
+moment of Os in this compound and, in general, of 5d$^1$ ions. Our results
+provide direct evidence of elusive Jahn-Teller distortions, hinting at a strong
+electron-lattice coupling.",2401.12035v1
+2024-03-29,Synthesis and Characterization of Superparamagnetic Iron Oxide Nanoparticles: A Series of Laboratory Experiments,"The following laboratory procedure provides students with a hands-on
+experience in nanomaterials chemistry and characterization. This three-day
+protocol is easy to follow for undergraduates with basic chemistry or materials
+science backgrounds and is suitable for inclusion in upper division courses in
+inorganic chemistry or materials science. Students use air-free chemistry
+procedures to synthesize and separate iron oxide magnetic nanoparticles and
+subsequently modify the nanoparticle surface using a chemical stripping agent.
+The morphology and chemical composition of the nanoparticles are characterized
+using electron microscopy and dynamic light scattering measurements.
+Additionally, magnetic characterization of the particles is performed using an
+open-source (3D-printed), inexpensive magnetophotometer. Possible modifications
+to the synthesis procedure including the incorporation of dopants to modify the
+magnetic response and alternative characterization techniques are discussed.
+The three-day synthesis, purification, and characterization laboratory will
+prepare students with crucial skills for advanced technology industries such as
+semiconductor manufacturing, nanomedicine, and green chemistry.",2403.19970v1
+1994-03-03,Effect of a magnetic field on Mott-Hubbard systems,"The effect of a magnetic field on Mott-Hubbard systems is investigated by
+studying the half-filled Hubbard model in the limit of infinite dimensions. A
+first-order metamagnetic transition between the strongly correlated metal and
+the Mott insulator is found for a critical value of the applied field. The
+field and temperature dependence of the magnetization, one-particle properties
+and susceptibility are studied and compared to the Gutzwiller approximation.
+The experimental relevance for transition-metal oxides and liquid $^{3}He$ is
+discussed.",9403016v1
+1994-09-19,Motion of a Single Hole in a Disordered Magnetic Background,"The spectrum of a single hole is calculated within the spin-hole model using
+a variational method. This calculation is done for any rotational invariant
+magnetic background. We have found that when the magnetic background changes
+from a disordered to a locally ordered state, the spectrum changes
+qualitatively. We have also found that the spin pattern around the hole is
+polarized. This problem is related to the study of copper oxide planes $CuO_2$
+doped with a small number of holes.",9409077v1
+1996-11-13,Dramatic Switching of Magnetic Exchange in a Classic Transition Metal Oxide: Evidence for Orbital Ordering,"Spin correlations in metallic and insulating phases of $V_2O_3$ and its
+derivatives are investigated using magnetic neutron scattering. Metallic
+samples have incommensurate spin correlations varying little with hole doping.
+Paramagnetic insulating samples have spin correlations only among near
+neighbors. The transition from either of these phases into the low temperature
+insulating antiferromagnetic phase is accompanied by an abrupt change of
+dynamic magnetic short range order. Our results support the idea that the
+transition into the antiferromagnetic insulator is also an orbital ordering
+transition.",9611109v1
+1999-10-25,Heavy Fermion Behaviors in LiV_{2}O_{4},"Experiments of various types on the metallic transition metal oxide compound
+LiV_{2}O_{4} with the fcc normal-spinel structure are reviewed. The
+low-temperature T < 10 K data consistently indicate heavy fermion (HF)
+behaviors characteristic of those of the heaviest-mass f-electron HF compounds.
+A crossover is observed above about 50 K in the magnetic susceptibility, ^{7}Li
+spin-lattice relaxation rate and neutron magnetic scattering function to a
+magnetic state variously described as an antiferromagnetically-coupled
+local-moment metal or, at the opposite extreme, as an itinerant
+nearly-ferromagnetic metal. Recent theoretical investigations to understand
+these properties of LiV_{2}O_{4} are discussed.",9910404v1
+2000-11-24,"Jahn-Teller, Charge and Magnetic Ordering in half-doped Manganese Oxides","The phase diagram of half-doped manganite systems of formula
+A_{0.5}A'_{0.5}MnO_3 is investigated within a single-orbital model
+incorporating magnetic double-exchange and superexchange, together with
+intersite Coulomb and electron-lattice interactions. Strong Jahn-Teller and
+breathing mode deformations compete together and result in shear lattice
+deformations. The latters stabilize the charge-ordered CE-type phase, which
+undergo first-order transitions with temperature or magnetic field to either
+Ferromagnetic metallic or Paramagnetic insulating phases. An essential feature
+is the self-consistent screening of Coulomb and electron-phonon interactions in
+the ferromagnetic phase.",0011419v1
+2001-05-09,Thermodynamics of the interplay between magnetism and high-temperature superconductivity,"The copper-oxide based high temperature superconductors have complex phase
+diagrams with multiple ordered phases. It even appears that the highest
+superconducting transition temperatures for certain cuprates are found in
+samples which display simultaneous onset of magnetism and superconductivity. We
+show here how the thermodynamics of fluid mixtures - a touchstone for chemists
+as well as hard and soft condensed matter physics - accounts for this startling
+observation, as well as many other properties of the cuprates in the vicinity
+of the instability towards ``striped'' magnetism.",0105200v3
+2001-06-06,Low Voltage I-V Characteristics in Magnetic Tunnel Junctions,"We show that elastic currents that take into account variations of the tunnel
+transmitivity with voltage and a large ratio of majority to minority spin
+densities of states of the $s$ band, can account for the low voltage current
+anomalies observed in magnet-oxide-magnet junctions. The anomalies can be
+positive, negative or have a mixed form, depending of the position of the Fermi
+level in the $s$ band, in agreement with observations. Magnon contribution is
+negligible small to account for the sharp drop of the magnetoresistance with
+the voltage bias.",0106123v1
+2002-01-14,Magnetic and superconducting properties of Cd2Re2O7: Cd NMR and Re NQR,"We report Cd NMR and Re NQR studies on Cd2Re2O7, the first superconductor
+among pyrochlore oxides Tc=1 K. Re NQR spectrum at zero magnetic field below
+100 K rules out any magnetic or charge order. The spin-lattice relaxation rate
+below Tc exhibits a pronounced coherence peak and behaves within the
+weak-coupling BCS theory with nearly isotropic energy gap. Cd NMR results point
+to moderate ferromagnetic enhancement at high temperatures followed by rapid
+decrease of the density of states below the structural transition temperature
+of 200 K.",0201215v1
+2002-04-21,Magnetic effect from non-magnetic impurity in superconducting CuO_{2} plane,"We propose a new model for impurity center formed by a cathion substitute for
+Cu, like Zn, in CuO_{2} planes. Its main effect on superconducting electrons is
+due to the non-zero exchange field on O sites, neighbors to the (non-magnetic)
+impurity. We discuss a strong suppression of d-wave order parameter, a zero-
+energy resonance in local density of states, and spin polarization of charge
+carriers, which can be related to the experimentally observed effects in
+Zn-doped copper oxides. These results are obtained \emph{without} using the
+unitary scattering limit.",0204454v1
+2004-01-16,Ferromagnetism in Fe-doped SnO2 thin films,"Thin films grown by pulsed-laser deposition from targets of Sn0.95Fe0.05O2
+are transparent ferromagnets with Curie temperature and spontaneous
+magnetization of 610 K and 2.2 Am2kg-1, respectively. The 57Fe Mossbauer
+spectra show the iron is all high-spin Fe3+ but the films are magnetically
+inhomogeneous on an atomic scale, with only 23 % of the iron ordering
+magnetically. The net ferromagnetic moment per ordered iron ion, 1.8 Bohr
+magnetons, is greater than for any simple iron oxide. Ferromagnetic coupling of
+ferric ions via an electron trapped in a bridging oxygen vacancy (F center) is
+proposed to explain the high Curie temperature",0401293v1
+2004-10-12,Evidence for magnetic clusters in BaCoO$_3$,"Magnetic properties of the transition metal oxide BaCoO$_3$ are analyzed on
+the basis of the experimental and theoretical literature available via ab inito
+calculations. These can be explained by assuming the material to be formed by
+noninteracting ferromagnetic clusters of about 1.2 nm in diameter separated by
+about 3 diameters. Above about 50 K, the so-called blocking temperature,
+superparamagnetic behavior of the magnetic clusters occurs and, above 250 K,
+paramagnetism sets in.",0410303v1
+2004-12-17,The low-energy electronic structure and the orbital magnetism in NiO,"The orbital and spin moment of the Ni2+ ion in NiO has been calculated within
+the quasi-atomic approach. The orbital moment of 0.46 mu_B amounts at 0 K, in
+the magnetically-ordered state, to about 20% of the total moment (2.45 mu_B).
+For this outcome, being in nice agreement with the recent experimental finding
+of the orbital moment, taking into account the intra-atomic spin-orbit coupling
+is indispensable.
+  PACS: 75.25.+z, 75.10.Dg
+  Keywords: Crystalline Electric Field, 3d oxides, magnetism, NiO",0412484v1
+2004-12-23,Why the magnetic interactions in Na$_{x}$CoO$_{2}$ are 3D,"The puzzle of 3D magnetic interactions in the structurally 2D layered oxide
+Na$_{x}$CoO$_2$ is addressed using first principles calculations and analysis
+of the exchange mechanisms. The calculations agree with recent neutron results,
+favoring AFM stacking of FM planes. Superexchange via direct O-O hopping and
+through intermediate Na $sp^2$ hybrids couples each Co to its nearest and six
+\textit{next}-nearest interplanar neighbors equally. The individual exchange
+constants are rather 2D, like the lattice itself, but due to multiple c-axis
+exchange paths, the magnetism becomes effectively 3D.",0412663v1
+2005-09-26,Interplay between mesoscopic phase separation and bulk magnetism in the layered NaxCoO2,"Specific heat of the layered NaxCoO2 (x=0.65, 0.70 and 0.75) oxides has been
+measured in the temperature range of 3-360 K and magnetic field of 0 and 9 T.
+The analysis of data, assuming the combined effect of inter-layer superexchange
+and the phase separation into mesoscopic magnetic domains with localized spins
+embedded in a matrix with itinerant electronic character, suggests that the
+dominant contribution to the specific heat in the region of short-range
+ordering is mediated by quasi-2D antiferromagnetic clusters, perpendicular to
+the CoO2 layers.",0509655v1
+2005-11-25,"Comment on a Phys. Rev. Lett. paper: ""All-Electron Self-Consistent GW Approximation: Application to Si, MnO, and NiO"". Magnetic moment of NiO","We claim that any approach neglecting the spin-orbit coupling and the orbital
+magnetism is not physically adequate for 3d oxides, including NiO, and that in
+reaching ""excellent agreement"" in a Phys. Rev. Lett. 93, 126406 (2004) paper
+too small experimental value of 1.9 muB has been taken for the Ni magnetic
+moment despite publication of a new experimental value of 2.2 muB, at 300 K
+yielding 2.6 muB at T = 0 K, already in a year of 1998.",0511624v1
+2006-02-24,Magnetic field-assisted manipulation and entanglement of Si spin qubits,"Architectures of donor-electron based qubits in silicon near an oxide
+interface are considered theoretically. We find that the precondition for
+reliable logic and read-out operations, namely the individual identification of
+each donor-bound electron near the interface, may be accomplished by
+fine-tuning electric and magnetic fields, both applied perpendicularly to the
+interface. We argue that such magnetic fields may also be valuable in
+controlling two-qubit entanglement via donor electron pairs near the interface.",0602597v2
+2006-08-28,Stripeless incommensurate magnetism in a doped strongly correlated oxide,"We studied the nano-scale structure of the short-range incommensurate
+magnetic order in La1.5Sr0.5CoO4 by elastic neutron scattering. We find that
+magnetic diffuse scattering is isotropic in the a-b plane, in contrast with the
+naive expectation based on the popular stripe model. Indeed, charge segregation
+into lines favoring certain lattice direction(s) would facilitate linear
+stacking faults in an otherwise robust antiferromagnetism of un-doped material,
+leading to anisotropic disorder, with a characteristic symmetry pattern present
+in the neutron scattering data.",0608575v3
+2007-02-26,Impurity Conduction and Magnetic Polarons in Antiferromagnetic Oxides,"Low-temperature transport and magnetization measurements for the
+antiferromagnets SrMnO(3) and CaMnO(3) identify an impurity band of mobile
+states separated by energy E from electrons bound in Coulombic potentials. Very
+weak electric fields are sufficient to excite bound electrons to the impurity
+band, increasing the mobile carrier concentration by more than three orders of
+magnitude. The data argue against the formation of self-trapped magnetic
+polarons (MPs) predicted by theory, and rather imply that bound MPs become
+stable only for kT<<E.",0702608v1
+2007-03-11,Hole states in wide band-gap diluted magnetic semiconductors and oxides,"Puzzling disagreement between photoemission and optical findings in
+magnetically doped GaN and ZnO is explained within a generalized alloy theory.
+The obtained results show that the strong coupling between valence-band holes
+and localized spins gives rise to a mid-gap Zhang-Rice-like state, to a sign
+reversal of the apparent p-d exchange integral, and to an increase of the
+band-gap with the magnetic ion concentration.",0703278v1
+2007-07-05,Anomalous exchange coupling in transition-metal-oxide based superlattices with antiferromagnetic spacer layers,"A direct correlation is seen between the coercive field (HC) and the
+magnetic-field-dependent resistivity (MR) in SrMnO3/SrRuO3 superlattices of
+perpendicular magnetic anisotropy. The magnetoresistance shows a sharp jump at
+Hc for in-plane current and the out-of-plane magnetic field. Both HC and
+high-field MR also oscillate with the thickness of the SrMnO3 spacer layers
+separating the metallic ruthenate. Since the spacer in these superlattices has
+no mobile carriers to facilitate an oscillatory coupling, we attribute the
+observed behavior to the spin-polarized quantum tunneling of electrons between
+the ferromagnetic layers and antiferromagnetically ordered t2g spins of SrMnO3.",0707.0768v1
+2008-05-24,Role of charge carriers for ferromagnetism in cobalt-doped rutile TiO2,"Electric and magnetic properties of a high temperature ferromagnetic oxide
+semiconductor, cobalt-doped rutile TiO2, are summarized. The cobalt-doped
+rutile TiO2 epitaxial thin films with different electron densities and cobalt
+contents were grown on r-sapphire substrates with laser molecular beam epitaxy.
+Results of magnetization, magnetic circular dichroism, and anomalous Hall
+effect measurements were examined for samples with systematically varied
+electron densities and cobalt contents. The samples with high electron
+densities and cobalt contents show the high temperature ferromagnetism,
+suggesting that charge carriers induce the ferromagnetism.",0805.3748v1
+2008-08-07,Incommensurate spin density modulation in a copper-oxide chain compound with commensurate charge order,"Neutron diffraction has been used to determine the magnetic structure of
+Na$_8$Cu$_5$O$_{10}$, a stoichiometric compound containing chains based on
+edge-sharing CuO$_4$ plaquettes. The chains are doped with 2/5 hole per Cu site
+and exhibit long-range commensurate charge order with an onset well above room
+temperature. Below $T_N = 23$ K, the neutron data indicate long-range collinear
+magnetic order with a spin density modulation whose propagation vector is
+commensurate along and incommensurate perpendicular to the chains. Competing
+interchain exchange interactions are discussed as a possible origin of the
+incommensurate magnetic order.",0808.1009v1
+2011-04-03,Dynamical magnetoelectric effects in multiferroic oxides,"Multiferroics with coexistent ferroelectric and magnetic orders can provide
+an interesting laboratory to test unprecedented magnetoelectric responses and
+their possible applications. One such example is the dynamical and/or resonant
+coupling between magnetic and electric dipoles in a solid. As the examples of
+such dynamical magnetoelectric effects, (1) the multiferroic domain wall
+dynamics and (2) the electric-dipole active magnetic responses are discussed
+with the overview of recent experimental observations.",1104.0357v1
+2011-07-03,Terahertz magnetoelectric response via electromagnons in magnetic oxides,"Terahertz magnetic resonance driven by the light electric field, now referred
+to as electromagnon, has stimulated interest due to its strong candidate for
+future spin-electronics. One unique characteristic of electromagnons is the
+terahertz magnetochromism, a color change by external magnetic field, as
+recently demonstrated in the hexaferrite. By taking perovskite manganites and
+hexaferrite as model cases, the current understating of the electromagnon
+activity is discussed in terms of the symmetric exchange mechanism.",1107.0428v1
+2012-09-23,On the Origin of Zigzag Magnetic Order in Iridium Oxide Na2IrO3,"We explore the phase diagram of spin-orbit Mott insulators on a honeycomb
+lattice, within the Kitaev-Heisenberg model extended to its full parameter
+space. Zigzag-type magnetic order is found to occupy a large part of the phase
+diagram of the model, and its physical origin is explained as due to
+interorbital t2g-eg hopping. Magnetic susceptibility and spin wave spectra are
+calculated and compared to the experimental data, obtaining thereby the spin
+coupling constants in Na2IrO3 and Li2IrO3.",1209.5100v1
+2012-11-15,Spin-Droplet State of an Interacting 2D Electron System,"We report thermodynamic magnetization measurements of two-dimensional
+electrons in several high mobility Si metal-oxide-semiconductor field-effect
+transistors. We provide evidence for an easily polarizable electron state in a
+wide density range from insulating to deep into the metallic phase. The
+temperature and magnetic field dependence of the magnetization is consistent
+with the formation of large-spin droplets in the insulating phase. These
+droplets melt in the metallic phase with increasing density and temperature,
+although they survive up to large densities.",1211.3536v1
+2012-11-30,Ab initio study of magnetic anisotropy in cobalt doped zinc oxide with electron-filling,"Based on first-principles calculation, it has been predicted that the
+magnetic anisotropy energy (MAE) in Co-doped ZnO (Co:ZnO) depends on
+electron-filling. Results show that the charge neutral Co:ZnO presents a ""easy
+plane"" magnetic state. While modifying the total number of electrons, the easy
+axis rotates from in-plane to out-of-plane. The alternation of the MAE is
+considered to be the change of the ground state of Co ion, resulting from the
+relocating of electrons on Co d-orbitals with electron-filling.",1211.7287v2
+2013-05-22,Electric control of the magnetization in BiFeO$_3$/LaFeO$_3$ superlattices,"First-principles techniques are used to investigate the behavior of
+BiFeO$_{3}$/LaFeO$_{3}$ perovskite oxide superlattices epitaxially grown on a
+(001)-SrTiO$_3$ substrate. The calculations show that 1/1 superlattices exhibit
+a $Pmc2_1$ ground state combining a trilinear coupling of one polar and two
+oxygen rotational lattice modes, and weak ferromagnetism. The microscopic
+mechanism allowing one to manipulate the magnetization with an electric field
+in such systems is presented and its dependence on strain and chemical
+substitution is discussed. BiFeO$_{3}$/LaFeO$_{3}$ artificial superlattices
+appear to be good candidates to achieve electric switching of magnetization at
+room temperature.",1305.5093v1
+2016-03-23,Large Magnetoresistance at Room Temperature in Ferromagnet/Topological Insulator Contacts,"We report magnetoresistance for current flow through iron/topological
+insulator (Fe/TI) and Fe/evaporated-oxide/TI contacts when a magnetic field is
+used to initially orient the magnetic alignment of the incorporated
+ferromagnetic Fe bar, at temperatures ranging from 100 K to room temperature.
+This magnetoresistance is associated with the relative orientation of the Fe
+bar magnetization and spin-polarization of electrons moving on the surface of
+the TI with helical spin-momentum locking. The magnitude of the observed
+magnetoresistance is relatively large compared to that observed in prior work.",1603.07283v1
+2017-08-09,Can Nitric Oxide be Evaporatively Cooled in its Ground State?,"Cold collisions of $^{14}$N$^{16}$O molecules in the $^{2}\Pi_{1/2}$ ground
+state, subject to electric and magnetic fields, are investigated. It is found
+that elastic collision rates significantly exceed state-changing inelastic
+rates only at temperatures above 0.5 K at laboratory strength fields. It is
+found, however, that in very large fields $> 10^{4}$ V/cm, inelastic rates can
+be somewhat suppressed. Magnetic fields have negligible influence on scattering
+for this nearly non-magnetic state.",1708.02875v1
+2013-09-12,Structural control of magnetic anisotropy in a strain driven multiferroic EuTiO3 thin film,"Octahedral distortion plays a key role in engineering the physical properties
+of heterostructures composed of perovskite oxides. We observe a strong in-plane
+uniaxial magnetic anisotropy in a strain-enabled multiferroic EuTiO3 thin film
+epitaxially grown on a (110)o DyScO3 substrate. First principles calculations
+show that the magnetic anisotropy is closely correlated with the uniaxial TiO6
+octahedral tilting and the ferroelectric polarization of the film, indicating
+potential strong magnetoelectric coupling in the strain-engineered multiferroic
+system.",1309.3185v1
+2017-09-08,Room temperature ferromagnetism in transparent and conducting Mn-doped $SnO_{2}$ thin films,"The magnetization as a function of magnetic field showed hysteretic behavior
+at room temperature. According to the temperature dependence of the
+magnetization, the Curie temperature $(T_{C})$ is higher than 350 K.
+Ferromagnetic Mn-doped tin oxide thin films exhibited low electrical
+resistivity and high optical transmittance in the visible region (400-800 nm).
+The coexistence of ferromagnetism, high visible transparency and high
+electrical conductivity in the Mn-doped $SnO_{2}$ films is expected to be a
+desirable trait for spintronics devices.",1709.05930v1
+2019-02-24,Spin interactions and magnetic order in the iron oxychalcogenides BaFe2Q2O,"The ability to tune the iron chalcogenides BaFe2Q3 from Mott insulators, to
+metals and then superconductors with applied pressure has renewed interest in
+low-dimensional iron chalcogenides and oxychalcogenides. We report here a
+combined experimental and theoretical study on the iron oxychalcogenides
+BaFe2Q2O (Q=S, Se) and show that their magnetic behaviour results from
+nearest-neighbour magnetic exchange interactions via oxide and selenide anions
+of similar strength, with properties consistent with more localised electronic
+structures than those of BaFe2Q3 systems.",1902.09035v2
+2021-09-21,Ferromagnetic Double Perovskite Semiconductors with Tunable Properties,"We successfully dope the magnetically silent double perovskite semiconductor
+Sr2GaSbO6 to induce ferromagnetism and tune its band gap, with Ga3+ partially
+substituted by the magnetic trivalent cation Mn3+, in a rigid cation ordering
+with Sb5+. Our new ferromagnetic semiconducting Sr2Ga1-xMnxSbO6 double
+perovskite, which crystallizes in tetragonal symmetry (space group I4/m) and
+has tunable ferromagnetic ordering temperature and band gap, suggests that
+magnetic ion doping of double perovskites is a productive avenue towards
+obtaining materials for application in next-generation oxide-based spintronic
+devices.",2109.10405v1
+2023-11-30,Spin-Dependent Capture Mechanism for Magnetic Field Effects on Interface Recombination Current in Semiconductor Devices,"Electrically detected magnetic resonance (EDMR) and near-zero field
+magnetoresistance (NZFMR) are techniques that probe defect states at dielectric
+interfaces critical for metal-oxide-semiconductor (MOS) electronic devices such
+as the Si/SiO$_2$ MOS field effect transistor (MOSFET). A comprehensive theory,
+adapted from the trap-assisted recombination theory of Shockley, Read, and
+Hall, is introduced to include the spin-dependent recombination effects that
+provide the mechanism for magnetic field sensitivity.",2312.14933v1
+2017-12-11,"Electronic structure, magnetism and exchange integrals in transition metal oxides: role of the spin polarization of the functional in DFT+$U$ calculations","Density functional theory augmented with Hubbard-$U$ corrections (DFT+$U$) is
+currently one of the widely used methods for first-principles electronic
+structure modeling of insulating transition metal oxides (TMOs). Since $U$ is
+relatively large compared to band widths, the magnetic excitations in TMOs are
+expected to be well described by a Heisenberg model. However, in practice the
+calculated exchange parameters $J_{ij}$ depend on the magnetic configuration
+from which they are extracted and on the functional used to compute them. In
+this work we investigate how the spin polarization dependence of the underlying
+exchange-correlation functional influences the calculated magnetic exchange
+constants of TMOs. We perform a systematic study of the predictions of
+calculations based on the local density approximation plus $U$ (LDA+$U$) and
+the local spin density approximation plus $U$ (LSDA+$U$) for the electronic
+structures, total energies and magnetic exchange interactions $J_{ij}$'s
+extracted from ferromagnetic (FM) and antiferromagnetic (AFM) configurations of
+several transition metal oxide materials. We report that, for realistic choices
+of Hubbard $U$ and Hund's $J$ parameters, LSDA+$U$ and LDA+$U$ calculations
+result in different values of the magnetic exchange constants and band gap. The
+dependence of the band gap on the magnetic configuration is stronger in LDA+$U$
+than in LSDA+$U$ and we argue that this is the main reason why the
+configuration dependence of the $J_{ij}$'s is found to be systematically more
+pronounced in LDA+$U$ than in LSDA+$U$ calculations. We report a very good
+correspondence between the computed total energies and the parameterized
+Heisenberg model for LDA+$U$ calculations, but not for LSDA+$U$, suggesting
+that LDA+$U$ is a more appropriate method for estimating exchange interactions.",1712.03907v3
+2021-03-14,Perpendicular magnetic anisotropy in ultra-thin Cu$_2$Sb-type (Mn-Cr)AlGe films onto thermally oxidized silicon substrates,"Perpendicularly magnetized films showing small saturation magnetization,
+$M_\mathrm{s}$, are essential for spin-transfer-torque writing type
+magnetoresistive random access memories, STT-MRAMs. An intermetallic compound,
+{(Mn-Cr)AlGe} of the Cu$_2$Sb-type crystal structure was investigated, in this
+study, as a material showing the low $M_\mathrm{s}$ ($\sim 300$ kA/m) and
+high-perpendicular magnetic anisotropy, $K_\mathrm{u}$. The layer thickness
+dependence of $K_\mathrm{u}$ and effects of Mg-insertion layers at top and
+bottom (Mn-Cr)AlGe$|$MgO interfaces were studied in film samples fabricated
+onto thermally oxidized silicon substrates to realize high-$K_\mathrm{u}$ in
+the thickness range of a few nanometer. Optimum Mg-insertion thicknesses were
+1.4 and 3.0 nm for the bottom and the top interfaces, respectively, which were
+relatively thick compared to results in similar insertion effect investigations
+on magnetic tunnel junctions reported in previous studies. The cross-sectional
+transmission electron microscope images revealed that the Mg-insertion layers
+acted as barriers to interdiffusion of Al-atoms as well as oxidization from the
+MgO layers. The values of $K_\mathrm{u}$ were about $7 \times 10^5$ and $2
+\times 10^5$ J/m$^3$ at room temperature for 5 and 3 nm-thick (Mn-Cr)AlGe
+films, respectively, with the optimum Mg-insertion thicknesses. The
+$K_\mathrm{u}$ at a few nanometer thicknesses is comparable or higher than
+those reported in perpendicularly magnetized CoFeB films which are
+conventionally used in MRAMs, while the $M_\mathrm{s}$ value is one third or
+less smaller than those of the CoFeB films. The developed (Mn-Cr)AlGe films are
+promising from the viewpoint of not only the magnetic properties, but also the
+compatibility to the silicon process in the film fabrication.",2103.07847v2
+2010-11-30,Neutron diffraction studies and the magnetism of an ordered perovskite: Ba2CoTeO6,"The complex perovskite Ba2CoTeO6 (BCTO) has been synthesised, and the crystal
+structure and magnetic properties have been investigated using a combination of
+X-ray and neutron powder diffraction, electron microscopy and dielectric,
+calorimetric and magnetic measurements. It was shown that at room temperature
+this compound adopts the 6L-trigonal perovskite structure, space group P-3m (N
+164) (a= 5.7996(1){\AA}, c=14.2658(3){\AA}). The structure comprises dimers of
+face-sharing octahedra as well as octahedra which share only vertices with
+their neighbours. A long-range antiferromagnetically ordered state has been
+identified from neutron diffraction and magnetic studies. The magnetic
+diffraction peaks were registered below the magnetic transition at about 15 K
+and a possible model for the magnetic structure is proposed. The structural and
+magnetic features of this compound are discussed and compared with those of
+other Co-based quaternary oxides adopting the perovskite structure.",1011.6637v1
+2017-02-03,"Evolution of structure, magnetism and electronic transport in doped pyrochlore iridate Y$_2$Ir$_{2-x}$Ru$_{x}$O$_7$","The interplay between spin-orbit coupling (SOC) and electron correlation
+($U$) is considered for many exotic phenomena in iridium oxides. We have
+investigated the evolution of structural, magnetic and electronic properties in
+pyrochlore iridate Y$_2$Ir$_{2-x}$Ru$_{x}$O$_7$ where the substitution of Ru
+has been aimed to tune this interplay. The Ru substitution does not introduce
+any structural phase transition, however, we do observe an evolution of lattice
+parameters with the doping level $x$. X-ray photoemission spectroscopy (XPS)
+study indicates Ru adopts charge state of Ru$^{4+}$ and replaces the Ir$^{4+}$
+accordingly. Magnetization data reveal both the onset of magnetic
+irreversibility and the magnetic moment decreases with progressive substitution
+of Ru. These materials show non-equilibrium low temperature magnetic state as
+revealed by magnetic relaxation data. Interestingly, we find magnetic
+relaxation rate increases with substitution of Ru. The electrical resistivity
+shows an insulating behavior in whole temperature range, however, resistivity
+decreases with substitution of Ru. Nature of electronic conduction has been
+found to follow power-law behavior for all the materials.",1702.01023v1
+2015-12-04,Magnetic proximity effect at interface between a cuprate superconductor and an oxide spin valve,"Heterostructures consisting of a cuprate superconductor YBa2Cu3O7x and a
+ruthenate/manganite (SrRuO3/La0.7Sr0.3MnO3) spin valve have been studied by
+SQUID magnetometry, ferromagnetic resonances and neutron reflectometry. It was
+shown that due to the influence of magnetic proximity effect a magnetic moment
+is induced in the superconducting part of heterostructure and at the same time
+the magnetic moment is suppressed in the ferromagnetic spin valve. The
+experimental value of magnetization induced in the superconductor has the same
+order of magnitude with the calculations based on the induced magnetic moment
+of Cu atoms due to orbital reconstruction at the superconductor-ferromagnetic
+interface. It corresponds also to the model that takes into account the change
+in the density of states at a distance of order of the coherence length in the
+superconductor. The experimentally obtained characteristic length of
+penetration of the magnetic moment into superconductor exceeds the coherence
+length for cuprate superconductor. This fact points on the dominance of the
+mechanism of the induced magnetic moment of Cu atoms due to orbital
+reconstruction.",1512.01336v1
+2016-11-30,Temperature-dependent magnetic anisotropy from directional-dependent interactions,"Magnetic anisotropy of spin models with directional-dependent interactions in
+the high-temperature paramagnetic phase is theoretically studied. Using a high
+temperature expansion, we show that the Ising type directional-dependent
+interaction gives rise to magnetic anisotropy which depends on the temperature
+as $\propto T^{-5}$. This phenomenon arises from the anisotropic exchange
+interaction, and is distinct from the orbital effect, such as van Vleck
+susceptibility. It is shown that while the quadratic term in the magnetization
+favors to point the spins along the bond, the fourth order term in
+magnetization prefers to point spins to the perpendicular direction. The theory
+is applied to the Heisenberg-Kitaev model on the honeycomb lattice and a cubic
+lattice model that is potentially relevant to perovskite iridates. We show
+that, in these models, the anisotropic terms in quadratic order cancels out,
+and the leading order for the magnetic anisotropy arises from the fourth order
+contribution. The result shows that the anisotropy from the
+directional-dependent interaction gives rise to $\langle100\rangle$ magnetic
+anisotropy. These results are potentially relevant to heavy transition metal
+oxides such as iridates. Experimental observation of the magnitude of
+anisotropic interactions using magnetic torque measurement is also discussed.",1612.00057v1
+2017-12-21,Thermal and magnetic field stability of holmium single atom magnets,"We use spin-polarized scanning tunneling microscopy to demonstrate that Ho
+atoms on magnesium oxide exhibit a coercive field of more than 8 T and magnetic
+bistability for many minutes, both at 35 K. The first spontaneous magnetization
+reversal events are recorded at 45 K for which the metastable state relaxes in
+an external field of 8 T. The transverse magnetic anisotropy energy is
+estimated from magnetic field and bias voltage dependent switching rates at 4.3
+K. Our measurements constrain the possible ground state of Ho single atom
+magnets to either Jz = 7 or 8, both compatible with magnetic bistability at
+fields larger than 10 mT.",1712.07871v1
+2019-10-03,Magnetization process of the breathing pyrochlore magnet CuInCr$_4$S$_8$ in ultra-high magnetic fields up to 150 T,"The magnetization process of the breathing pyrochlore magnet CuInCr4S8 has
+been investigated in ultra-high magnetic fields up to 150 T. Successive phase
+transitions characterized with a substantially wide 1/2-plateau from 55 T to
+110 T are observed in this system, resembling those reported in chromium spinel
+oxides. In addition to the 1/2-plateau phase, the magnetization is found to
+exhibit two inherent behaviors: a slight change in the slope of the M-H curve
+at ~ 85 T and a shoulder-like shape at ~ 130 T prior to the saturation. Both of
+them are accompanied by a hysteresis, suggesting first-order transitions. The
+theoretical calculation applicable to CuInCr4S8 is also shown, based on the
+microscopic model with the spin-lattice coupling. The calculation fairly well
+reproduces the main features of the experimentally observed magnetization
+process, including a relatively wide cant 2:1:1 phase clearly observed in the
+previous work [Y. Okamoto et al., J. Phys. Soc. Jpn. 87, 034709 (2018)]. The
+robust 1/2-plateau on CuInCr4S8 seems to be originated from the dominant
+antiferromagnetic interactions and the strong spin-lattice coupling.",1910.01315v1
+2018-06-26,Ultrahigh Magnetic Fields Produced by Shearing Carbon Nanotubes,"In laboratories, ultrahigh magnetic fields are usually produced with very
+large currents through superconducting, resistive or hybrid magnets, which
+require extreme conditions, such as low temperature, huge cooling water or tens
+of megawatts of power. In this work we report that when single walled carbon
+nanotubes (SWNTs) are cut, there are magnetic moments at the shearing end of
+SWNTs. The average magnetic moment is found to be 41.5+-9.8uB per carbon atom
+in the end states with a width of 1 nm at temperature of 300.0K, suggesting
+ultrahigh magnetic fields can be produced. The dangling sigma and pi bonds of
+the carbon atoms at the shearing ends play important roles for this
+unexpectedly high magnetic moments because the oxidation temperature of cut
+SWNTs is found to be as low as 312 in dry air. Producing ultrahigh magnetic
+field with SWNTs has the advantage of working at higher working temperature and
+with low energy consumption, suggesting great potentials of applications.",1806.09891v1
+2019-11-30,Phono-magnetic analogs to opto-magnetic effects,"The magneto-optical and opto-magnetic effects describe the interaction of
+light with a magnetic medium. The most prominent examples are the Faraday and
+Cotton-Mouton effects that modify the transmission of light through a medium,
+and the inverse Faraday and inverse Cotton-Mouton effects that produce
+effective magnetic fields for the spin in the material. Here, we introduce the
+phenomenology of the analogous magneto-phononic and phono-magnetic effects, in
+which vibrational quanta take the place of the light quanta. We show, using a
+combination of first-principles calculations and phenomenological modeling,
+that the effective magnetic fields exerted by the phonon analogs of the inverse
+Faraday and inverse Cotton-Mouton effects on the spins of antiferromagnetic
+nickel oxide yield magnitudes comparable to and potentially larger than those
+of the opto-magnetic originals.",1912.00129v2
+2023-06-20,Giant effective magnetic moments of chiral phonons from orbit-lattice coupling,"Circularly polarized lattice vibrations carry angular momentum and lead to
+magnetic responses in applied magnetic fields or when resonantly driven with
+ultrashort laser pulses. Recent measurements have found responses that are
+orders of magnitude larger than those calculated in prior theoretical studies.
+Here, we present a microscopic model for the effective magnetic moments of
+chiral phonons in magnetic materials that is able to reproduce the
+experimentally measured magnitudes and that allows us to make quantitative
+predictions for materials with giant magnetic responses using microscopic
+parameters. Our model is based on orbit-lattice couplings that hybridize
+optical phonons with orbital electronic transitions. We apply our model to two
+types of materials: $4f$ rare-earth halide paramagnets and $3d$
+transition-metal oxide magnets. In both cases, we find that chiral phonons can
+carry giant effective magnetic moments of the order of a Bohr magneton, orders
+of magnitude larger than previous predictions.",2306.11630v1
+2011-03-22,Dipolar Interactions between Iron-Oxide Nanoparticles in Frozen Ferrofluids and Ferronematics,"We present a detailed study of the magnetic behavior of iron-oxide
+(gamma-Fe2O3 and Fe3O4) nanoparticles constituents of ferrofluids (FF's) with
+average particle sizes <d> = 2.5 and 10 nm. The particles were dispersed in the
+frozen liquid carrier (pure FF) and in a frozen lyotropic liquid crystalline
+matrix in the nematic phase or ferronematic (FN) (ferrolyomesophase). Both FF
+and FN phases displayed superparamagnetic (SPM) behaviour at room temperature,
+with blocking temperatures T_B ~ 10 and 100 K for <d> = 2.5 and 10 nm,
+respectively. Dynamic ac susceptibility measurements showed a thermally
+activated N\'eel-Brown dependence of the blocking temperature with applied
+frequency. Our results show that dipolar interactions are small, but
+non-negligible, as compared to the single-particle energy barriers from
+magnetic anisotropy. From the fit of ac susceptibility we calculated the
+effective magnetic anisotropy constant K_{eff} for 2.5 nm maghemite particles.
+Although interparticle interactions present in highly diluted samples do not
+appreciably modify the dynamic magnetic behavior of isolated particles, the
+calculated magnetic anisotropy were abut one order of magnitude larger that the
+bulk materials, suggesting the existence of large surface anisotropy. Using the
+thermally activated model to fit the dynamic data yielded effective energy
+barriers Ea = 3.5x10^{-21} J. From these data, we obtained K_{eff} = 422 kJ/m^3
+for the single-particle effective magnetic anisotropy.",1103.4403v1
+2012-02-13,Nature of magnetic excitations in superconducting BaFe$_{1.9}$Ni$_{0.1}$As$_{2}$,"Since the discovery of the metallic antiferromagnetic (AF) ground state near
+superconductivity in iron-pnictide superconductors, a central question has been
+whether magnetism in these materials arises from weakly correlated electrons,
+as in the case of spin-density-wave in pure chromium, requires strong electron
+correlations, or can even be described in terms of localized electrons such as
+the AF insulating state of copper oxides. Here we use inelastic neutron
+scattering to determine the absolute intensity of the magnetic excitations
+throughout the Brillouin zone in electron-doped superconducting
+BaFe$_{1.9}$Ni$_{0.1}$As$_{2}$ ($T_c=20$ K), which allows us to obtain the size
+of the fluctuating magnetic moment $<m^2>$, and its energy distribution. We
+find that superconducting BaFe$_{1.9}$Ni$_{0.1}$As$_{2}$ and AF BaFe$_2$As$_2$
+both have fluctuating magnetic moments $<m^2>\approx3.2\ \mu_B^2$ per Fe(Ni),
+which are similar to those found in the AF insulating copper oxides. The common
+theme in both classes of high temperature superconductors is that magnetic
+excitations have partly localized character, thus showing the importance of
+strong correlations for high temperature superconductivity.",1202.2827v1
+2013-04-04,Learning from Nature to Improve the Heat Generation of Iron-Oxide Nanoparticles for Magnetic Hyperthermia Applications,"The performance of magnetic nanoparticles is intimately entwined with their
+structure, mean size and magnetic anisotropy. Besides, ensembles offer a unique
+way of engineering the magnetic response by modifying the strength of the
+dipolar interactions between particles. Here we report on an experimental and
+theoretical analysis of magnetic hyperthermia, a rapidly developing technique
+in medical research and oncology. Experimentally, we demonstrate that
+single-domain cubic iron oxide particles resembling bacterial magnetosomes have
+superior magnetic heating efficiency compared to spherical particles of similar
+sizes. Monte Carlo simulations at the atomic level corroborate the larger
+anisotropy of the cubic particles in comparison with the spherical ones, thus
+evidencing the beneficial role of surface anisotropy in the improved heating
+power. Moreover we establish a quantitative link between the particle
+assembling, the interactions and the heating properties. This knowledge opens
+new perspectives for improved hyperthermia, an alternative to conventional
+cancer therapies.",1304.1298v1
+2014-12-22,Inverse magneto-refraction as a mechanism for laser modification of spin-spin exchange parameters and subsequent terahertz emission from iron oxides,"Ultrafast non-thermal manipulation of magnetization by light relies on either
+indirect coupling of the electric field component of the light with spins via
+spin-orbit interaction or direct coupling between the magnetic field component
+and spins. Here we propose a novel scenario for coupling between the electric
+field of light and spins via optical modification of the exchange interaction,
+one of the strongest quantum effects, the strength of which can reach 1000
+Tesla. We demonstrate that this isotropic opto-magnetic effect, which can be
+called the inverse magneto-refraction, is allowed in a material of any
+symmetry. Its existence is corroborated by the experimental observation of THz
+emission by magnetic-dipole active spin resonances optically excited in a broad
+class of iron oxides with a canted spin configuration. From its strength we
+estimate that a sub-picosecond laser pulse with a moderate fluence of ~ 1
+mJ/cm^2 acts as a pulsed effective magnetic field of 0.01 Tesla, arising from
+the optically perturbed balance between the exchange parameters. Our findings
+are supported by a low-energy theory for the microscopic magnetic interactions
+between non-equilibrium electrons subjected to an optical field which suggests
+a possibility to modify the exchange interactions by light over 1 %.",1412.7094v1
+2016-03-31,"Theory of multiple--phase competition in pyrochlore magnets with anisotropic exchange, with application to Yb2Ti2O7, Er2Ti2O7 and Er2Sn2O7","The family of magnetic rare-earth pyrochlore oxides R2M2O7 plays host to a
+diverse array of exotic phenomena, driven by the interplay between geometrical
+frustration and spin-orbit interaction, which leads to anisotropy in both
+magnetic moments and their interactions. In this article we establish a
+general, symmetry--based theory of pyrochlore magnets with anisotropic exchange
+interactions. Starting from a very general model of nearest-neighbour exchange
+between Kramers ions, we find four distinct classical ordered states, all with
+q=0, competing with a variety of spin-liquids and unconventional forms of
+magnetic order. The finite-temperature phase diagram of this model is
+determined by Monte Carlo simulation, supported by classical spin-wave
+calculations. We pay particular attention to the region of parameter space
+relevant to the widely studied materials Er2Ti2O7, Yb2Ti2O7, and Er2Sn2O7. We
+find that many of the most interesting properties of these materials can be
+traced back to the ""accidental"" degeneracies where phases with different
+symmetries meet. These include the ordered ground state selection by
+fluctuations in Er2Ti2O7, the dimensional-reduction observed in Yb2Ti2O7, and
+the lack of reported magnetic order in Er2Sn2O7. We also discuss the
+application of this theory to other pyrochlore oxides.",1603.09466v2
+2010-05-07,Magnetic ground state of pyrochlore oxides close to metal-insulator boundary probed by muon spin rotation,"Magnetism of ruthernium pyrochlore oxides A2Ru2O7 (A = Hg, Cd, Ca), whose
+electronic properties within a localized ion picture are characterized by
+non-degenerate t2g orbitals (Ru5+, 4d3) and thereby subject to geometrical
+frustration, has been investigated by muon spin rotation/relaxation (muSR)
+technique. The A cation (mostly divalent) was varied to examine the effect of
+covalency (Hg > Cd > Ca) on their electronic property. In a sample with A = Hg
+that exhibits a clear metal-insulator (MI) transition below >> 100 K (which is
+associated with a weak structural transition), a nearly commensurate magnetic
+order is observed to develop in accordance with the MI transition. Meanwhile,
+in the case of A = Cd where the MI transition is suppressed to the level of
+small anomaly in the resistivity, the local field distribution probed by muon
+indicates emergence of a certain magnetic inhomogeneity below {\guillemotright}
+30 K. Moreover, in Ca2Ru2O7 that remains metallic, we find a highly
+inhomogeneous local magnetism below >>25 K that comes from randomly oriented Ru
+moments and thus described as a ""frozen spin liquid"" state. The systematic
+trend of increasing randomness and itinerant character with decreasing
+covalency suggests close relationship between these two characters. As a
+reference for the effect of orbital degeneracy and associated Jahn-Teller
+instability, we examine a tetravalent ruthernium pyrochlore, Tl2Ru2O7 (Ru4+,
+4d4), where the result of muSR indicates a non-magnetic ground state that is
+consistent with the formation of the Haldane chains suggested by neutron
+diffraction experiment.",1005.1133v2
+2014-06-28,Disorder in a Quantum Critical Superconductor,"In four classes of materials, the layered copper-oxides, organics,
+iron-pnictides and heavy-fermion compounds, an unconventional superconducting
+state emerges as a magnetic transition is tuned toward absolute zero
+temperature, that is, toward a magnetic quantum-critical point (QCP). In most
+materials, the QCP is accessed by chemical substitutions or applied pressure.
+CeCoIn5 is one of the few materials that are born as a quantum-critical
+superconductor and, therefore, offers the opportunity to explore the
+consequences of chemical disorder. Cadmium-doped crystals of CeCoIn5 are a
+particularly interesting case where Cd substitution induces long-range magnetic
+order, as in Zn-doped copper-oxides. Applied pressure globally supresses the
+Cd-induced magnetic order and restores bulk superconductivity. Here we show,
+however, that local magnetic correlations, whose spatial extent decreases with
+applied pressure, persist at the extrapolated QCP. The residual droplets of
+impurity-induced magnetic moments prevent the reappearance of conventional
+signatures of quantum criticality, but induce a heterogeneous electronic state.
+These discoveries show that spin droplets can be a source of electronic
+heterogeneity in classes of strongly correlated electron systems and emphasize
+the need for caution when interpreting the effects of tuning a correlated
+system by chemical substitution.",1406.7370v1
+2015-12-01,Magnetization reversal of an individual exchange biased permalloy nanotube,"We investigate the magnetization reversal mechanism in an individual
+permalloy (Py) nanotube (NT) using a hybrid magnetometer consisting of a
+nanometer-scale SQUID (nanoSQUID) and a cantilever torque sensor. The Py NT is
+affixed to the tip of a Si cantilever and positioned in order to optimally
+couple its stray flux into a Nb nanoSQUID. We are thus able to measure both the
+NT's volume magnetization by dynamic cantilever magnetometry and its stray flux
+using the nanoSQUID. We observe a training effect and temperature dependence in
+the magnetic hysteresis, suggesting an exchange bias. We find a low blocking
+temperature $T_B = 18 \pm 2$ K, indicating the presence of a thin
+antiferromagnetic native oxide, as confirmed by X-ray absorption spectroscopy
+on similar samples. Furthermore, we measure changes in the shape of the
+magnetic hysteresis as a function of temperature and increased training. These
+observations show that the presence of a thin exchange-coupled native oxide
+modifies the magnetization reversal process at low temperatures. Complementary
+information obtained via cantilever and nanoSQUID magnetometry allows us to
+conclude that, in the absence of exchange coupling, this reversal process is
+nucleated at the NT's ends and propagates along its length as predicted by
+theory.",1512.00199v1
+2021-10-13,Nonmonotonic magnetic field dependence of remanent ferroelectric polarization in reduced-graphene-oxide-BiFeO$_3$ nanocomposite,"In a nanocomposite of reduced graphene oxide (RGO) and BiFeO$_3$ (BFO), the
+remanent ferroelectric polarization is found to follow nonmonotonic magnetic
+field dependence at room temperature as the applied magnetic field is swept
+across 0-20 kOe on a pristine sample. The remanent ferroelectric polarization
+is determined both from direct electrical measurements on an assembly of
+nanoparticles and powder neutron diffraction patterns recorded under 0-20 kOe
+field. The nanosized ($\sim$20 nm) particles of BFO are anchored onto the
+graphene sheets of RGO via Fe-C bonds with concomitant rise in covalency in the
+Fe-O bonds. The field-dependent competition between the positive and negative
+magnetoelectric coupling arising from magnetostriction due to, respectively,
+interface and bulk magnetization appears to be giving rise to the observed
+nonmonotonic field dependence of polarization. The emergence of Fe-C bonds and
+consequent change in the magnetic and electronic structure of the interface
+region has influenced the coupling between ferroelectric and magnetic
+properties remarkably and thus creates a new way of tuning the magnetoelectric
+properties via reconstruction of interfaces in nanocomposites or
+heterostructures of graphene/single-phase-multiferroic systems.",2110.06519v1
+2021-11-20,Exchange coupling in synthetic anion-engineered chromia heterostructures,"Control of magnetic states by external factors has garnered a mainstream
+status in spintronic research for designing low power consumption and
+fast-response information storage and processing devices. Previously,
+magnetic-cation substitution is the conventional means to induce ferromagnetism
+in an intrinsic antiferromagnet. Theoretically, the anion-doping is proposed to
+be another effect means to change magnetic ground states. Here we demonstrate
+the synthesis of high-quality single-phase chromium oxynitride thin films using
+in-situ nitrogen doping. Unlike antiferromagnetic monoanionic chromium oxide
+and nitride phases, chromium oxynitride exhibits a robust ferromagnetic and
+insulating state, as demonstrated by the combination of multiple magnetization
+probes and theoretical calculations. With increasing the nitrogen content, the
+crystal structure of chromium oxynitride transits from trigonal (R3c) to
+tetragonal (4mm) phase and its saturation magnetization reduces significantly.
+Furthermore, we achieve a large and controllable exchange bias field in the
+chromia heterostructures by synthetic anion engineering. This work reflects the
+anion engineering in functional oxides towards the potential applications in
+giant magnetoresistance and tunnelling junctions of modern magnetic sensors and
+read heads.",2111.10564v1
+2022-07-31,Interface Engineering Enabled Low Temperature Growth of Magnetic Insulator on Topological Insulator,"Combining topological insulators (TIs) and magnetic materials in
+heterostructures is crucial for advancing spin-based electronics. Magnetic
+insulators (MIs) can be deposited on TIs using the spin-spray process, which is
+a unique non-vacuum, low-temperature growth process. TIs have highly reactive
+surfaces that oxidize upon exposure to atmosphere, making it challenging to
+grow spin-spray ferrites on TIs. In this work, it is demonstrated that a thin
+titanium capping layer on TI, followed by oxidation in atmosphere to produce a
+thin TiOx interfacial layer, protects the TI surface, without significantly
+compromising spin transport from the magnetic material across the TiOx to the
+TI surface states. First, it was demonstrated that in Bi2Te3/TiOx/Ni80Fe20
+heterostructures that TiOx provided an excellent barrier against diffusion of
+magnetic species, yet maintained a large spin-pumping effect. Second, the TiOx
+was also used as a protective capping layer on Bi2Te3, followed by the
+spin-spray growth of the MI, NixZnyFe2O4 (NZFO). For the thinnest TiOx
+barriers, Bi2Te3/TiOx/NZFO samples had AFM disordered interfacial layer because
+of diffusion. With increasing TiOx barrier thickness, the diffusion was
+reduced, but still maintained strong interfacial spin-pumping interaction.
+These experimental results demonstrate a novel method of low-temperature growth
+of magnetic insulators on TIs enabled by interface engineering.",2208.00499v1
+2013-11-23,Universal Scaling Law to Predict the Efficiency of Magnetic Nanoparticles as MRI T2-Contrast Agents,"Magnetic particles are very efficient Magnetic Resonance Imaging (MRI)
+contrast agents. In the recent years, chemists have unleashed their imagination
+to design multi-functional nanoprobes for biomedical applications including MRI
+contrast enhancement. This study is focused on the direct relationship between
+the size and magnetization of the particles and their nuclear magnetic
+resonance relaxation properties, which condition their efficiency. Experimental
+relaxation results with maghemite particles exhibiting a wide range of sizes
+and magnetizations are compared to previously published data and to
+well-established relaxation theories with a good agreement. This allows
+deriving the experimental master curve of the transverse relaxivity versus
+particle size and to predict the MRI contrast efficiency of any type of
+magnetic nanoparticles. This prediction only requires the knowledge of the size
+of the particles impermeable to water protons and the saturation magnetization
+of the corresponding volume. To predict the T2 relaxation efficiency of
+magnetic single crystals, the crystal size and magnetization obtained through a
+single Langevin fit of a magnetization curve is the only information needed.
+For contrast agents made of several magnetic cores assembled into various
+geometries (dilute fractal aggregates, dense spherical clusters, core-shell
+micelles, hollow vesicles), one needs to know a third parameter, namely the
+intra-aggregate volume fraction occupied by the magnetic materials relatively
+to the whole (hydrodynamic) sphere. Finally a calculation of the maximum
+achievable relaxation effect and the size needed to reach this maximum is
+performed for different cases: maghemite single crystals and dense clusters,
+core-shell particles (oxide layer around a metallic core) and zinc manganese
+ferrite crystals.",1311.6022v1
+2022-03-22,Co-loading of doxorubicin and iron oxide nanocubes in polycaprolactone fibers for combining Magneto-Thermal and chemotherapeutic effects on cancer cells,"Among the strategies to fight cancer, multi-therapeutic approaches are
+considered as a wise choice to put in place multiple weapons to suppress
+tumors. In this work, to combine chemotherapeutic effects to magnetic
+hyperthermia when using biocompatible scaffolds, we have established an
+electrospinning method to produce nanofibers of polycaprolactone loaded with
+magnetic nanoparticles as heat mediators to be selectively activated under
+alternating magnetic field and doxorubicin as a chemotherapeutic drug.
+Production of the fibers was investigated with iron oxide nanoparticles of
+peculiar cubic shape (at 15 and 23 nm in cube edges) as they provide benchmark
+heat performance under clinical magnetic hyperthermia conditions. With 23 nm
+nanocubes when included into the fibers, an arrangement in chains was obtained.
+This linear configuration of magnetic nanoparticles resemble that of the
+magnetosomes, produced by magnetotactic bacteria, and our magnetic fibers
+exhibited remarkable heating effects as the magnetosomes. Magnetic fiber
+scaffolds showed excellent biocompatibility on fibroblast cells when missing
+the chemotherapeutic agent and when not exposed to magnetic hyperthermia as
+shown by viability assays. On the contrary, the fibers containing both magnetic
+nanocubes and doxorubicin showed significant cytotoxic effects on cervical
+cancer cells following the exposure to magnetic hyperthermia. Notably, these
+tests were conducted at magnetic hyperthermia field conditions of clinical use.
+As here shown, on the doxorubicin sensitive cervical cancer cells, the
+combination of heat damage by magnetic hyperthermia with enhanced diffusion of
+doxorubicin at therapeutic temperature are responsible for a more effective
+oncotherapy.",2203.12380v1
+2016-07-05,Delayed hepatic uptake of multi-phosphonic acid poly(ethylene glycol) coated iron oxide measured by real-time Magnetic Resonance Imaging,"We report on the synthesis, characterization, stability and pharmacokinetics
+of novel iron based contrast agents for magnetic resonance imaging (MRI).
+Statistical copolymers combining multiple phosphonic acid groups and
+poly(ethylene glycol) (PEG) were synthesized and used as coating agents for 10
+nm iron oxide nanocrystals. In vitro, protein corona and stability assays show
+that phosphonic acid PEG copolymers outperform all other coating types
+examined, including low molecular weight anionic ligands and polymers. In vivo,
+the particle pharmacokinetics is investigated by monitoring the MRI signal
+intensity from mouse liver, spleen and arteries as a function of the time,
+between one minute and seven days after injection. Iron oxide particles coated
+with multi-phosphonic acid PEG polymers are shown to have a blood circulation
+lifetime of 250 minutes, i.e. 10 to 50 times greater than that of recently
+published PEGylated probes and benchmarks. The clearance from the liver takes
+in average 2 to 3 days and is independent of the core size, coating and
+particle stability. By comparing identical core particles with different
+coatings, we are able to determine the optimum conditions for stealth MRI
+probes.",1607.01656v1
+2008-07-20,"Nearly Isotropic superconductivity in (Ba,K)Fe2As2","Superconductivity was recently observed in the iron-arsenic-based compounds
+with a superconducting transition temperature (Tc) as high as 56K [1-7],
+naturally raising comparisons with the high Tc copper oxides. The copper oxides
+have layered crystal structures with quasi-two-dimensional electronic
+properties, which led to speculations that reduced dimensionality (that is,
+extreme anisotropy) is a necessary prerequisite for superconductivity at
+temperatures above 40 K [8,9]. Early work on the iron-arsenic compounds seemed
+to support this view [7,10]. Here we report measurements of the electrical
+resistivity in single crystals of (Ba,K)Fe2As2 in a magnetic field up to 60 T.
+We find that the superconducting properties are in fact quite isotropic, being
+rather independent of the direction of the applied magnetic fields at low
+temperature. Such behaviour is strikingly different from all previously-known
+layered superconductors [9,11], and indicates that reduced dimensionality in
+these compounds is not a prerequisite for high-temperature superconductivity.
+We suggest that this situation arises because of the underlying electronic
+structure of the iron-arsenide compounds, which appears to be much more three
+dimensional than that of the copper oxides. Extrapolations of low-field
+single-crystal data incorrectly suggest a high anisotropy and a greatly
+exaggerated zero-temperature upper critical field.",0807.3137v4
+2018-01-24,Interplay between superconductivity and magnetism in one-unit-cell LaAlO3 capped with SrTiO3,"To form a conducting layer at the interface between the oxide insulators
+LaAlO3 and SrTiO3, the LaAlO3 layer on the SrTiO3 substrate must be at least
+four unit-cells-thick. The LaAlO3 SrTiO3 heterointerface thus formed exhibits
+various intriguing phenomena such as ferromagnetism and superconductivity. It
+has been widely studied for being a low-dimensional ferromagnetic oxide
+superconducting system with a strong gate-tunable spin-orbit interaction.
+However, its lack of stability and environmental susceptiveness have been an
+obstacle to its further experimental investigations and applications. Here, we
+demonstrate that capping the bilayer with SrTiO3 relieves this thickness limit,
+while enhancing the stability and controllability of the interface. In
+addition, the SrTiO3-capped LaAlO3 exhibits unconventional superconductivity;
+the critical current dramatically increases under a parallel magnetic field,
+and shows a reversed hysteresis contrary to the conventional hysteresis of
+magnetoresistance. Its superconducting energy gap of $\Delta \sim 1.31k_BT_c$
+also deviates from conventional BCS-type superconductivity. The oxide trilayer
+could be a robust platform for studying the extraordinary interplay of
+superconductivity and ferromagnetism at the interface electron system between
+LaAlO3 and SrTiO3.",1801.08022v1
+2021-11-23,Elucidating the local atomic and electronic structure of amorphous oxidized superconducting niobium films,"Qubits made from superconducting materials are a mature platform for quantum
+information science application such as quantum computing. However,
+materials-based losses are now a limiting factor in reaching the coherence
+times needed for applications. In particular, knowledge of the atomistic
+structure and properties of the circuit materials is needed to identify,
+understand, and mitigate materials-based decoherence channels. In this work we
+characterize the atomic structure of the native oxide film formed on Nb
+resonators by comparing fluctuation electron microscopy experiments to density
+functional theory calculations, finding that an amorphous layer consistent with
+an Nb$_2$O$_5$ stoichiometry. Comparing X-ray absorption measurements at the
+Oxygen K edge with first-principles calculations, we find evidence of d-type
+magnetic impurities in our sample, known to cause impedance in proximal
+superconductors. This work identifies the structural and chemical composition
+of the oxide layer grown on Nb superconductors, and shows that soft X-ray
+absorption can fingerprint magnetic impurities in these superconducting
+systems.",2111.11590v1
+2022-01-11,High-throughput determination of Hubbard U and Hund J values for transition metal oxides via linear response formalism,"DFT+U provides a convenient, cost-effective correction for the
+self-interaction error (SIE) that arises when describing correlated electronic
+states using conventional approximate density functional theory (DFT). The
+success of a DFT+U(+J) calculation hinges on the accurate determination of its
+Hubbard U and Hund's J parameters, and the linear response (LR) methodology has
+proven to be computationally effective and accurate for calculating these
+parameters. This study provides a high-throughput computational analysis of the
+U and J values for transition metal d-electron states in a representative set
+of over 2000 magnetic transition metal oxides (TMOs), providing a frame of
+reference for researchers who use DFT+U to study transition metal oxides. In
+order to perform this high-throughput study, an atomate workflow is developed
+for calculating U and J values automatically on massively parallel
+supercomputing architectures. To demonstrate an application of this workflow,
+the spin-canting magnetic structure and unit cell parameters of the
+multiferroic olivine LiNiPO4 are calculated using the computed Hubbard U and
+Hund J values for Ni-d and O-p states, and are compared with experiment. Both
+the Ni-d U and J corrections have a strong effect on the Ni-moment canting
+angle. Additionally, including a O-p U value results in a significantly
+improved agreement between the computed lattice parameters and experiment.",2201.04213v2
+2022-02-22,Multiplet Effects in the Electronic Correlation of One-Dimensional Magnetic Transition-Metal Oxides on Metals,"We use the constrained random phase approximation (cRPA) method to calculate
+the Hubbard $U$ parameter in four one-dimensional magnetic transition metal
+atom oxides of composition XO$_2$ (X = Mn, Fe, Co, Ni) on Ir(100). In addition
+to the expected screening of the oxide, i.e., a significant reduction of the
+$U$ value by the presence of the metal substrate, we find a strong dependence
+on the electronic configuration (multiplet) of the X($d$) orbital. Each
+particular electronic configuration attained by atom X is dictated by the O
+ligands, as well as by the charge transfer and hybridization with the Ir(100)
+substrate. We find that MnO$_2$ and NiO$_2$ chains exhibit two different
+screening regimes, while the case of CoO$_2$ is somewhere in between. The
+electronic structure of the MnO$_2$ chain remains almost unchanged upon
+adsorption. Therefore, in this regime, the additional screening is
+predominantly generated by the electrons of the neighboring metal surface
+atoms. The screening strength for NiO$_2$/Ir(100) is found to depend on the
+Ni($d$) configuration in the adsorbed state. The case of FeO$_2$ shows an
+exceptional behavior, as it is the only insulating system in the absence of
+metallic substrate and, thus, it has the largest $U$ value. However, this value
+is significantly reduced by the two mentioned screening effects after
+adsorption.",2202.10805v1
+2011-10-07,Evolution of magnetic properties in the normal spinel solid solution Mg(1-x)Cu(x)Cr2O4,"We examine the evolution of magnetic properties in the normal spinel oxides
+Mg(1-x)Cu(x)Cr2O4 using magnetization and heat capacity measurements. The
+end-member compounds of the solid solution series have been studied in some
+detail because of their very interesting magnetic behavior. MgCr2O4 is a highly
+frustrated system that undergoes a first order structural transition at its
+antiferromagnetic ordering temperature. CuCr2O4 is tetragonal at room
+temperature as a result of Jahn-Teller active tetrahedral Cu^2+ and undergoes a
+magnetic transition at 135 K. Substitution of magnetic cations for diamagnetic
+Mg^2+ on the tetrahedral A site in the compositional series Mg(1-x)Cu(x)Cr2O4
+dramatically affects magnetic behavior. In the composition range 0 < x < 0.3,
+the compounds are antiferromagnetic. A sharp peak observed at 12.5K in the heat
+capacity of MgCr2O4 corresponding to a magnetically driven first order
+structural transition is suppressed even for small x suggesting glassy
+disorder. Uncompensated magnetism - with open magnetization loops - develops
+for samples in the x range 0.43 < x < 1. Multiple magnetic ordering
+temperatures and large coercive fields emerge in the intermediate composition
+range 0.43 < x < 0.47. The Neel temperature increases with increasing x across
+the series while the value of the Curie-Weiss Theta decreases. A magnetic
+temperature-composition phase diagram of the solid solution series is
+presented.",1110.1662v1
+2016-01-19,Collective magnetic response of CeO2 nanoparticles,"The magnetism of nanoparticles and thin films of wide-bandgap oxides that
+include no magnetic cations is an unsolved puzzle. Progress has been hampered
+both by the irreproducibility of much of the experimental data, and the lack of
+any generally-accepted theoretical explanation. The characteristic signature is
+a virtually anhysteretic, temperature-independent magnetization curve which
+saturates in an applied field that is several orders of magnitude greater than
+the magnetization. It appears as if a tiny volume fraction, < 0.1%, of the
+samples is magnetic and that the energy scale of the problem is unusually high
+for spin magnetism. Here we investigate the effect of dispersing 4 nm CeO2
+nanoparticles with powders of gamma-Al2O3, sugar or latex microspheres. The
+saturation magnetization, Ms ~ 60 A/m for compact samples, is maximized by 1
+wt% lanthanum doping. Dispersing the CeO2 nanopowder reduces its magnetic
+moment by up to an order of magnitude. There is a characteristic length scale
+of order 100 nm for the magnetism to appear in CeO2 nanoparticle clusters. The
+phenomenon is explained in terms of a giant orbital paramagnetism that appears
+in coherent mesoscopic domains due to resonant interaction with zero-point
+fluctuations of the vacuum electromagnetic field. The theory explains the
+observed temperature-independent magnetization curve and its doping and
+dispersion dependence, based on a length scale of 300 nm that corresponds to
+the wavelength of a maximum in the UV absorption spectrum of the magnetic CeO2
+nanoparticles. The coherent domains occupy roughly ten percent of the sample
+volume.",1601.04933v1
+2016-12-19,Evidence of room temperature magnetoelectric properties in α-Fe1.6Ga0.4O3 oxide by magnetic field controlled electric properties and electric field controlled magnetism,"We have stabilized the {\alpha}-Fe1.6Ga0.4O3 (Ga doped {\alpha}-Fe2O3) system
+in rhombohedral structure. The system has shown magnetically canted
+ferromagnetic state and ferroelectric properties at room temperature. In first
+time, we confirm the existence of magneto-electric coupling and
+multiferro-electric properties at room temperature in the Ga doped
+{\alpha}-Fe2O3 system based on the experimental observation of magnetic field
+controlled electric polarization and electric field controlled magnetization.
+The {\alpha}-Fe2O3 system does not exhibit electric field controlled magnetic
+exchange bias effect, where as Ga doped {\alpha}-Fe2O3 showed exchange bias
+shift up to the value of 370 Oe. We have recorded the response of
+current-voltage characteristics and in-field magnetic relaxation of the system
+under the simultaneous application of magnetic and electric fields. The
+magnetization of the system is found highly sensitive to the ON and OFF modes,
+as well as change of the polarity of external electric field. The system is a
+new addition in the list of non-traditional
+magneto-electrics/multi-ferroelectrics so far reported in literature. Such
+novel materials, where magnetization and electric polarization can be
+controlled by simultaneous application of magnetic and electric fields, is in
+the increasing demand for potential applications in the field of next
+generation magnetic sensor, switching, non-volatile memory and spintronic
+devices.",1612.06049v1
+2019-07-12,New method for characterization of magnetic nanoparticles by scanning magnetic microscopy,"In this paper, we present a new method for the magnetic characterization of
+bulk materials, microstructures, and nanostructures. We investigated the
+magnetic and morphological properties of two colloidal dispersions of iron
+oxide (Fe3O4) magnetic nanoparticles (MNPs), synthesized by chemical
+precipitation (co-precipitation) and pulsed laser ablation (PLA) in liquid, by
+scanning magnetic microscopy (SMM) applied to a small sample with mass on the
+order of tens of {\mu}g. We evaluated the performance of this technique by
+comparing magnetization curves and measurements obtained with commercial
+magnetometers, considered standard. The errors obtained for the saturation and
+remanent magnetization were approximately 0.18 Am2/kg and 0.6 Am2/kg,
+respectively. The average size distribution of the NPs estimated from the
+magnetization curve measurements is consistent with the results obtained by
+traditional transmission electron microscopy (TEM). The technique can be
+extended to measure and analyze magnetization curves (hysteresis loops), thus
+enabling an even more accurate estimation of overall NP sizes.",1907.05908v1
+2023-09-28,On-Command Disassembly of Microrobotic Superstructures for Transport and Delivery of Magnetic Micromachines,"Magnetic microrobots have been developed for navigating microscale
+environments by means of remote magnetic fields. However, limited propulsion
+speeds at small scales remain an issue in the maneuverability of these devices
+as magnetic force and torque are proportional to their magnetic volume. Here,
+we propose a microrobotic superstructure, which, as analogous to a
+supramolecular system, consists of two or more microrobotic units that are
+interconnected and organized through a physical (transient) component (a
+polymeric frame or a thread). Our superstructures consist of microfabricated
+magnetic helical micromachines interlocked by a magnetic gelatin nanocomposite
+containing iron oxide nanoparticles (IONPs). While the microhelices enable the
+motion of the superstructure, the IONPs serve as heating transducers for
+dissolving the gelatin chassis via magnetic hyperthermia. In a practical
+demonstration, we showcase the superstructure's motion with a gradient magnetic
+field in a large channel, the disassembly of the superstructure and release of
+the helical micromachines by a high-frequency alternating magnetic field, and
+the corkscrew locomotion of the released helices through a small channel via a
+rotating magnetic field. This adaptable microrobotic superstructure reacts to
+different magnetic inputs, which could be used to perform complex delivery
+procedures within intricate regions of the human body.",2310.04433v1
+2006-06-20,"Terrestrial planetary dynamics: a view from U, Th geochemistry","The migration of U and Th inside a planet is controlled by its oxidation
+state imposed by the volatile composition. In the deep interior of a planet, an
+absence of oxidative volatiles will cause U and Th to stay in a state of metal
+or low valance compounds with a big density. Consequently, they migrate to the
+bottom of its mantle first, and then are gradually sequestered to its liquid
+metal core. Earth is rich in oxidative volatiles including water, therefore, U
+and Th in the core can be moved up by an internal circulation system consisting
+of the outer core, hot super plumes, asthenosphere and subduction zone (or cold
+super plumes). This internal circulation system is the key for the formation of
+plate tectonics, the geodynamo and the consequent geomagnetic field. Moreover,
+plentiful oxidative volatiles and water within Earth is the precondition to
+form such a circulation system. In the early stage (> 4 Ga), Mars developed an
+Earth-like internal circulation system due to relatively large amount of
+oxidative volatile compositions coming from its building material. This would
+have produced a dynamo and correspondingly an Earth-like magnetic field.
+However, this internal circulation system was destroyed by one or several giant
+impact events in the early stage, which drove off these volatile compositions.
+These events also shaped the striking hemispheric dichotomy structure on the
+Martian surface. The other result is that its dynamo and geomagnetic field have
+also disappeared. Since then, Mars has been the same as Mercury and Venus in
+that the heat release from the U and Th in their cores can not be moved by an
+internal circulation system gently, but by sporadically catastrophic
+resurfacing events (Venus), or super plumes (Mars) or gradual heat conduction
+(Mercury).",0606468v4
+2014-12-19,Contact-induced charge contributions to non-local spin transport measurements in Co/MgO/graphene devices,"Recently, it has been shown that oxide barriers in graphene-based non-local
+spin-valve structures can be the bottleneck for spin transport. The barriers
+may cause spin dephasing during or right after electrical spin injection which
+limit spin transport parameters such as the spin lifetime of the whole device.
+An important task is to evaluate the quality of the oxide barriers of both spin
+injection and detection contacts in a fabricated device. To address this issue,
+we discuss the influence of spatially inhomogeneous oxide barriers and
+especially conducting pinholes within the barrier on the background signal in
+non-local measurements of graphene/MgO/Co spin-valve devices. By both
+simulations and reference measurements on devices with non-ferromagnetic
+electrodes, we demonstrate that the background signal can be caused by
+inhomogeneous current flow through the oxide barriers. As a main result, we
+demonstrate the existence of charge accumulation next to the actual spin
+accumulation signal in non-local voltage measurements, which can be explained
+by a redistribution of charge carriers by a perpendicular magnetic field
+similar to the classical Hall effect. Furthermore, we present systematic
+studies on the phase of the low frequency non-local ac voltage signal which is
+measured in non-local spin measurements when applying ac lock-in techniques.
+This phase has so far widely been neglected in the analysis of non-local spin
+transport. We demonstrate that this phase is another hallmark of the
+homogeneity of the MgO spin injection and detection barriers. We link backgate
+dependent changes of the phase to the interplay between the capacitance of the
+oxide barrier to the quantum capacitance of graphene.",1412.6224v1
+2018-02-02,Energetics of oxygen-octahedra rotations in perovskite oxides from first principles,"We use first-principles methods to study oxygen-octahedra rotations in ABO3
+perovskite oxides. We focus on the short-period, perfectly antiphase or
+in-phase, tilt patterns that characterize most compounds and control their
+physical (e.g., conductive, magnetic) properties. Based on an analytical form
+of the relevant potential energy surface, we discuss the conditions for the
+stability of polymorphs presenting different tilt patterns, and obtain
+numerical results for a collection of thirty-five representative materials. Our
+results reveal the mechanisms responsible for the frequent occurrence of a
+particular structure that combines antiphase and in-phase rotations, i.e., the
+orthorhombic Pbnm phase displayed by about half of all perovskite oxides and by
+many non-oxidic perovskites. The Pbnm phase benefits from the simultaneous
+occurrence of antiphase and in-phase tilt patterns that compete with each
+other, but not as strongly as to be mutually exclusive. We also find that
+secondary antipolar modes, involving the A cations, contribute to weaken the
+competition between different tilts and play a key role in their coexistence.
+Our results thus confirm and better explain previous observations for
+particular compounds. Interestingly, we also find that strain effects, which
+are known to be a major factor governing phase competition in related (e.g.,
+ferroelectric) perovskite oxides, play no essential role as regards the
+relative stability of different rotational polymorphs. Further, we discuss why
+the Pbnm structure stops being the ground state in two opposite limits, for
+large and small A cations, showing that very different effects become relevant
+in each case. Our work thus provides a comprehensive discussion on these
+all-important and abundant materials, which will be useful to better understand
+existing compounds as well as to identify new strategies for materials
+engineering.",1802.00784v1
+2020-09-28,Control of skyrmion chirality in Ta/FeCoB/TaOx trilayers by TaOx oxidation and FeCoB thickness,"Skyrmions are magnetic bubbles with nontrivial topology envisioned as data
+bits for ultrafast and power-efficient spintronic memory and logic devices.
+They may be stabilized in heavy-metal/ferromagnetic/oxide trilayer systems. The
+skyrmion chirality is then determined by the sign of the interfacial
+Dzyaloshinskii-Moriya interaction (DMI). Nevertheless, for apparently identical
+systems, there is some controversy about the DMI sign. Here, we show that the
+degree of oxidation of the top interface and the thickness of the ferromagnetic
+layer play a major role. Using Brillouin light-scattering measurements in
+Ta/Fe-Co-B/TaOx trilayers, we demonstrate a sign change of the DMI with the
+degree of oxidation of the Fe-Co-B/TaOx interface. Using polar magneto-optical
+Kerr effect microscopy, we consistently observe a reversal of the direction of
+current-induced motion of skyrmions with the oxidation level of TaOx; this is
+attributed to their chirality reversal. In addition, a second chirality
+reversal is observed when changing the Fe-Co-B thickness, probably due to the
+proximity of the two Fe-Co-B interfaces in the ultrathin case. By properly
+tuning the chirality of the skyrmion, spin-transfer and spin-orbit torques
+combine constructively to enhance the skyrmion velocity. These observations
+thus allow us to envision an optimization of the material parameters to produce
+highly mobile skyrmions. Moreover, this chirality control enables a versatile
+manipulation of skyrmions and paves the way towards multidirectional devices.",2009.13136v3
+2021-10-16,Generalized estimates for thermal expansion of oxide scale in the range from 0C to 1300C with account for movability of phase transitions in its components,"The thermophysical properties of oxide scale, in the general case, are
+affected by the variation of the temperature of phase transitions (either
+magnetic or polymorphic) in its components due to impurities, lattice defects,
+grain sizes, etc. In this case, since the phase transition is usually
+accompanied by a sharp change in properties, even a small shift of such a
+critical temperature can lead to large changes in properties in its vicinity.
+In order to account for this effect, data known from various sources on the
+true coefficient of linear thermal expansion (CLTE) of w\""ustite , magnetite ,
+hematite , and metallic iron are generalized by approximating functions that
+include critical temperatures as variable parameters. It is shown that the true
+CLTE of magnetite at the same rated temperature can differ by up to 30%
+depending on the position of the Curie point within the limits of its possible
+""movability"". The proposed methods allow to take into account the critical
+temperatures as adaptation parameters in engineering calculations of thermal
+expansion of oxide scale. Generalized formulas for each scale component are
+also given in a particular form for fixed (basic) values of critical
+temperatures. The dependence of the true CLTE of oxide scale as a whole
+({\alpha}sc) on the volume fraction of each component is proposed. It is shown
+by model computations that there are temperatures at which {\alpha}sc is almost
+independent of the scale composition, as well as areas of instability, where
+{\alpha}sc depends significantly on the percentage of components. The results
+of the work are recommended to be used when mathematical modeling of production
+and processing of steel products in the presence of oxide scale on their
+surface.",2110.08528v1
+2023-09-22,Ultrathin Magnesium-based Coating as an Efficient Oxygen Barrier for Superconducting Circuit Materials,"Scaling up superconducting quantum circuits based on transmon qubits
+necessitates substantial enhancements in qubit coherence time. Among the
+materials considered for transmon qubits, tantalum (Ta) has emerged as a
+promising candidate, surpassing conventional counterparts in terms of coherence
+time. However, the presence of an amorphous surface Ta oxide layer introduces
+dielectric loss, ultimately placing a limit on the coherence time. In this
+study, we present a novel approach for suppressing the formation of tantalum
+oxide using an ultrathin magnesium (Mg) capping layer deposited on top of
+tantalum. Synchrotron-based X-ray photoelectron spectroscopy (XPS) studies
+demonstrate that oxide is confined to an extremely thin region directly beneath
+the Mg/Ta interface. Additionally, we demonstrate that the superconducting
+properties of thin Ta films are improved following the Mg capping, exhibiting
+sharper and higher-temperature transitions to superconductive and magnetically
+ordered states. Based on the experimental data and computational modeling, we
+establish an atomic-scale mechanistic understanding of the role of the capping
+layer in protecting Ta from oxidation. This work provides valuable insights
+into the formation mechanism and functionality of surface tantalum oxide, as
+well as a new materials design principle with the potential to reduce
+dielectric loss in superconducting quantum materials. Ultimately, our findings
+pave the way for the realization of large-scale, high-performance quantum
+computing systems.",2309.12603v2
+2020-10-16,Sudden collapse of magnetic order in oxygen deficient nickelate films,"Oxygen vacancies play a crucial role in the control of the electronic,
+magnetic, ionic, and transport properties of functional oxide perovskites. Rare
+earth nickelates (RENiO$_{3-x}$) have emerged over the years as a rich platform
+to study the interplay between the lattice, the electronic structure, and
+ordered magnetism. In this study, we investigate the evolution of the
+electronic and magnetic structure in thin films of RENiO$_{3-x}$, using a
+combination of X-ray absorption spectroscopy and imaging, resonant X-ray
+scattering, and extended multiplet ligand field theory modeling. We find that
+oxygen vacancies modify the electronic configuration within the Ni-O orbital
+manifolds, leading to a dramatic evolution of long-range electronic transport
+pathways despite the absence of nanoscale phase separation. Remarkably,
+magnetism is robust to substantial levels of carrier doping, and only a
+moderate weakening of the $(1/4, 1/4, 1/4)_{pc}$ antiferromagnetic order
+parameter is observed, whereas the magnetic transition temperature is largely
+unchanged. Only at a certain point long-range magnetism is abruptly erased
+without an accompanying structural transition. We propose the progressive
+disruption of the 3D magnetic superexchange pathways upon introduction of point
+defects as the mechanism behind the sudden collapse of magnetic order in
+oxygen-deficient nickelates. Our work demonstrates that, unlike most other
+oxides, ordered magnetism in RENiO$_{3-x}$ is mostly insensitive to carrier
+doping. The sudden collapse of ordered magnetism upon oxygen removal may
+provide a new mechanism for solid-state magneto-ionic switching and new
+applications in antiferromagnetic spintronics.",2010.08545v1
+2006-02-28,Magnetic field dependence of the magnetic phase separation in Pr1-xCaxMnO3 manganites studied by small-angle neutron scattering,"Transport properties of manganese oxides suggest that their colossal
+magnetoresistance (CMR) is due to percolation between ferromagnetic metallic
+(FM) clusters in an antiferromagnetic insulating (AFI) matrix. We have studied
+small-angle neutron scattering under applied magnetic field in CMR Pr1-xCaxMnO3
+crystals for x around 0.33. Quantitative analysis of the small-angle magnetic
+neutron scattering shows that the magnetic heterogeneities take place at
+different scales. At the mesoscopic scale (200nm), the inhomogeneities
+correspond to the percolation of the conducting ferromagnetic phase into the
+insulating phases. It is at the origin of the colossal magnetoresistance of the
+compound. The other inhomogeneities are nanoscopic: inside the
+antiferromagnetic phase (AFI), there exist small ferromagnetic clusters. Inside
+the ferromagnetic phase which exists in absence of magnetic field in some
+compounds and is in fact insulating (FI), there also exist small non
+ferromagnetic objects. No evolution of this nanostructure is observed when the
+magnetic field is applied. The existence of such nanoscale objects is discussed
+in relation to the cationic disorder of these compounds.",0602668v1
+2006-08-14,Nitrogen based magnetic semiconductors,"We describe a possible pathway to new magnetic materials with no conventional
+magnetic elements present. The substitution of Nitrogen for Oxygen in simple
+non magnetic oxides leads to holes in N 2$p$ states which form local magnetic
+moments. Because of the very large Hund's rule coupling of Nitrogen and O 2$p$
+electrons and the rather extended spatial extend of the wave functions these
+materials are predicted to be ferromagnetic metals or small band gap
+insulators. Experimental studies support the theoretical calculations with
+regard to the basic electronic structure and the formation of local magnetic
+moments. It remains to be seen if these materials are magnetically ordered and
+if so below what temperature.",0608313v1
+2006-11-19,Magnetic coupling in CoCr_2O_4 and MnCr_2O_4: an LSDA+U study,"We present a first principles LSDA+U study of the magnetic coupling constants
+in the spinel magnets CoCr_2O_4 and MnCr_2O_4. Our calculated coupling
+constants highlight the possible importance of AA interactions in spinel
+systems with magnetic ions on both A and B sites. Furthermore, we show that a
+careful analysis of the dependence of the magnetic coupling constants on the
+LSDA+U parameters provides valuable insights in the underlying coupling
+mechanisms, and allows to obtain a quantitative estimate of the magnetic
+coupling constants. We discuss in detail the capabilities and possible pitfalls
+of the LSDA+U method in determining magnetic coupling constants in complex
+transition metal oxides.",0611502v3
+2008-01-31,Impurity-Ion pair induced high-temperature ferromagnetism in Co-doped ZnO,"Magnetic 3d-ions doped into wide-gap oxides show signatures of room
+temperature ferromagnetism, although their concentration is two orders of
+magnitude smaller than that in conventional magnets. The prototype of these
+exceptional materials is Co-doped ZnO, for which an explanation of the room
+temperature ferromagnetism is still elusive. Here we demonstrate that magnetism
+originates from Co2+ oxygen-vacancy pairs with a partially filled level close
+to the ZnO conduction band minimum. The magnetic interaction between these
+pairs is sufficiently long-ranged to cause percolation at moderate
+concentrations. However, magnetically correlated clusters large enough to show
+hysteresis at room temperature already form below the percolation threshold and
+explain the current experimental findings. Our work demonstrates that the
+magnetism in ZnO:Co is entirely governed by intrinsic defects and a phase
+diagram is presented. This suggests a recipe for tailoring the magnetic
+properties of spintronics materials by controlling their intrinsic defects.",0801.4945v1
+2010-03-12,Magnetic interaction of Co ions near the {10\bar{1}0} ZnO surface,"Co-doped ZnO is the prototypical dilute magnetic oxide showing many of the
+characteristics of ferromagnetism. The microscopic origin of the long range
+order however remains elusive, since the conventional mechanisms for the
+magnetic interaction, such as super-exchange and double exchange, fail either
+at the fundamental or at a quantitative level. Intriguingly, there is a growing
+evidence that defects both in point-like or extended form play a fundamental
+role in driving the magnetic order. Here we explore one of such possibilities
+by performing {\it ab initio} density functional theory calculations for the
+magnetic interaction of Co ions at or near a ZnO \{10$\bar{1}$0\} surface. We
+find that extended surface states can hybridize with the $e$-levels of Co and
+efficiently mediate the magnetic order, although such a mechanism is effective
+only for ions placed in the first few atomic planes near the surface. We also
+find that the magnetic anisotropy changes at the surface from an hard-axis
+easy-plane to an easy axis, with an associated increase of its magnitude. We
+then conclude that clusters with high densities of surfacial Co ions may
+display blocking temperatures much higher than in the bulk.",1003.2576v1
+2010-04-13,Incommensurate magnetic order and dynamics induced by spinless impurities in YBa$_2$Cu$_3$O$_{6.6}$,"We report an inelastic-neutron-scattering and muon-spin-relaxation study of
+the effect of 2% spinless (Zn) impurities on the magnetic order and dynamics of
+YBa$_2$Cu$_3$O$_{6.6}$, an underdoped high-temperature superconductor that
+exhibits a prominent spin-pseudogap in its normal state. Zn substitution
+induces static magnetic order at low temperatures and triggers a large-scale
+spectral-weight redistribution from the magnetic resonant mode at 38 meV into
+uniaxial, incommensurate spin excitations with energies well below the
+spin-pseudogap. These observations indicate a competition between
+incommensurate magnetic order and superconductivity close to a quantum critical
+point. Comparison to prior data on La$_{2-x}$Sr$_x$CuO$_{4}$ suggests that this
+behavior is universal for the layered copper oxides and analogous to
+impurity-induced magnetic order in one-dimensional quantum magnets.",1004.2139v1
+2011-04-29,New type of incommensurate magnetic ordering in Mn3TeO6,"The complex metal oxide Mn3TeO6 exhibits a corundum related structure and has
+been prepared both in forms of single crystals by chemical transport reactions
+and of polycrystalline powders by a solid state reaction route. The crystal
+structure and magnetic properties have been investigated using a combination of
+X-ray and neutron powder diffraction, electron microscopy, calorimetric and
+magnetic measurements. At room temperature this compound adopts a trigonal
+structure, space group R3 with a = 8.8679(1) {\AA}, c = 10.6727(2) {\AA}. A
+long-range magnetically ordered state is identified below 23 K. An unexpected
+feature of this magnetic structure is several types of Mn-chains. Under the
+action of the incommensurate magnetic propagation vector k = [0, 0, 0.4302(1)]
+the unique Mn site is split into two magnetically different orbits. One orbit
+forms a perfect helix with the spiral axis along the c-axis while the other
+orbit has a sine wave character along the c-axis.",1104.5560v1
+2011-05-23,Novel Magnetic Phases Revealed by Ultra-High Magnetic Field in the Frustrated Magnet ZnCr2O4,"The Faraday rotation technique is used to map out the finite-temperature
+phase diagram of the prototypical frustrated magnet ZnCr2O4, in magnetic fields
+of up to 190 T generated by the single-turn coil method. We find evidence for a
+number of magnetic phase transitions, which are well-described by the theory
+based on spin-lattice coupling. In addition to the 1/2 plateau and a 3:1 canted
+phase, a 2:1:1 canted phase is found for the first time in chromium spinel
+oxides, which has been predicted by a theory of Penc et al. to realize in a
+small spin-lattice coupling limit. Both the new 2:1:1 and the 3:1 phase are
+regarded as the supersolid phases according to a magnetic analogy of Matsuda
+and Tsuneto, and Liu and Fisher.",1105.4412v1
+2011-05-26,Magneto-structural transitions in a frustrated magnet at high fields,"Ultrasound and magnetization studies of bond-frustrated ZnCr2S4 spinel are
+performed in static magnetic fields up to 18 T and in pulsed fields up to 62 T.
+At temperatures below the antiferromagnetic transition at T_N1 14 K the sound
+velocity as function of magnetic field reveals a sequence of steps followed by
+plateaus indicating a succession of crystallographic structures with constant
+stiffness. At the same time, the magnetization evolves continuously with field
+up to full magnetic polarization without any plateaus in contrast to
+geometrically frustrated chromium oxide spinels. The observed high-field
+magneto-structural states are discussed within a H-T phase diagram taking into
+account the field and temperature evolution of three coexisting spin structures
+and subsequent lattice transformations induced by magnetic field.",1105.5220v1
+2014-07-02,Element-Specific Depth Profile of Magnetism and Stoichiometry at the La0.67Sr0.33MnO3/BiFeO3 Interface,"Depth-sensitive magnetic, structural and chemical characterization is
+important in the understanding and optimization of novel physical phenomena
+emerging at interfaces of transition metal oxide heterostructures. In a
+simultaneous approach we have used polarized neutron and resonant X-ray
+reflectometry to determine the magnetic profile across atomically sharp
+interfaces of ferromagnetic La0.67Sr0.33MnO3 / multiferroic BiFeO3 bi-layers
+with sub-nanometer resolution. In particular, the X-ray resonant magnetic
+reflectivity measurements at the Fe and Mn resonance edges allowed us to
+determine the element specific depth profile of the ferromagnetic moments in
+both the La0.67Sr0.33MnO3 and BiFeO3 layers. Our measurements indicate a
+magnetically diluted interface layer within the La0.67Sr0.33MnO3 layer, in
+contrast to previous observations on inversely deposited layers. Additional
+resonant X-ray reflection measurements indicate a region of an altered Mn- and
+O-content at the interface, with a thickness matching that of the magnetic
+diluted layer, as origin of the reduction of the magnetic moment.",1407.0737v1
+2015-02-05,Domain structure and perpendicular magnetic anisotropy in CoFe/Pd multilayers using off-axis electron holography,"Multilayers of Co90Fe10/Pd with different bilayer thicknesses, have been
+deposited by dc-magnetron sputtering on thermally oxidized Si wafers.
+Transmission electron microscopy showed that the highly textured crystalline
+films had columnar structure, while scanning transmission electron microscopy
+and atomic force microscopy respectively indicated some layer waviness and
+surface roughness. The magnetic domain structure and perpendicular magnetic
+anisotropy (PMA) of the Co90Fe10/Pd multilayers were investigated by off-axis
+electron holography and magnetic force microscopy. The Co90Fe10 layer thickness
+was the primary factor determining the magnetic domain size and the
+perpendicular magnetization: both decreased as the thickness increased. The
+strongest PMA was observed in the sample with the thinnest magnetic layer of
+0.45 nm.",1502.01422v1
+2015-02-19,Plentiful magnetic moments in oxygen deficient SrTiO3,"Correlated band theory is employed to investigate the magnetic and electronic
+properties of different arrangements of oxygen di- and tri-vacancy clusters in
+SrTiO$_3$. Hole and electron doping of oxygen deficient SrTiO$_3$ yields
+various degrees of magnetization as a result of the interaction between
+localized magnetic moments at the defected sites. Different kinds of Ti atomic
+orbital hybridization are described as a function of the doping level and
+defect geometry. We find that magnetism in SrTiO$_{3-\delta}$ is sensitive to
+the arrangement of neighbouring vacancy sites, charge carrier density, and
+vacancy-vacancy interaction. Permanent magnetic moments in the absence of
+vacancy doping electrons are observed. Our description of the charged clusters
+of oxygen vacancies widens the previous descriptions of mono and
+multi-vacancies and points out the importance of the controled formation at the
+atomic level of defects for the realization of transition metal oxide based
+devices with a desirable magnetic performance.",1502.05749v1
+2015-05-27,Microscopic analysis of the magnetic form factor in low-dimensional cuprates,"We analyze the magnetic form factor of Cu$^{2+}$ in low-dimensional quantum
+magnets by taking the metal-ligand hybridization into account explicitly. In
+this analysis we use the form of magnetic Wannier orbitals, derived from the
+first-principles calculations, and identify the contributions of different
+atomic sites. Having performed local density approximation calculations for
+cuprates with different types of ligand atoms, we discuss the influence of the
+on-site Coulomb correlations on the structure of the magnetic orbital. The
+typical composition of Wannier functions for copper oxides, chlorides and
+bromides is defined and related to features of the magnetic form factor. We
+propose easy-to-use approximations of the partial orbital contributions to the
+magnetic form factor in order to give a microscopic explanation for the results
+obtained in previous first-principles studies.",1505.07288v1
+2015-09-17,Dynamics of magnetic single domain particles embedded in a viscous liquid,"Kinetic equations for magnetic nano particles dispersed in a viscous liquid
+are developed and analyzed numerically. Depending on the amplitude of an
+applied oscillatory magnetic field the particles orient their time averaged
+anisotropy axis perpendicular to the applied field for low magnetic field
+amplitudes and nearly parallel to the direction of the field for high
+amplitudes. The transition between these regions takes place in a narrow field
+interval. In the low field region the magnetic moment is locked to some crystal
+axis and the energy absorption in an oscillatory driving field is dominated by
+viscous losses associated with particle rotation in the liquid. In the opposite
+limit the magnetic moment rotates within the particle while its easy axis being
+nearly parallel to the external field direction oscillates. The kinetic
+equations are generalized to include thermal fluctuations. This leads to a
+significant increase of the power absorption in the low and intermediate field
+region with a pronounced absorption peak as function of particle size. In the
+high field region, on the other hand, the inclusion of thermal fluctuations
+reduces the power absorption. The illustrative numerical calculations presented
+are performed for magnetic parameters typical for iron oxide.",1509.05233v1
+2017-02-28,Magnetic ground state of SrRuO$_3$ thin film and applicability of standard first-principles approximations to metallic magnetism,"A systematic first-principles study has been performed to understand the
+magnetism of thin film SrRuO$_3$ which lots of research efforts have been
+devoted to but no clear consensus has been reached about its ground state
+properties. The relative t$_{2g}$ level difference, lattice distortion as well
+as the layer thickness play together in determining the spin order. In
+particular, it is important to understand the difference between two standard
+approximations, namely LDA and GGA, in describing this metallic magnetism.
+Landau free energy analysis and the magnetization-energy-ratio plot clearly
+show the different tendency of favoring the magnetic moment formation, and it
+is magnified when applied to the thin film limit where the experimental
+information is severely limited. As a result, LDA gives a qualitatively
+different prediction from GGA in the experimentally relevant region of strain
+whereas both approximations give reasonable results for the bulk phase. We
+discuss the origin of this difference and the applicability of standard methods
+to the correlated oxide and the metallic magnetic systems.",1702.08647v2
+2017-03-06,Magnetically induced Ferroelectricity in Bi$_2$CuO$_4$,"The tetragonal copper oxide Bi$_2$CuO$_4$ has an unusual crystal structure
+with a three-dimensional network of well separated CuO$_4$ plaquettes. This
+material was recently predicted to host electronic excitations with an
+unconventional spectrum and the spin structure of its magnetically ordered
+state appearing at T$_N$ $\sim$43 K remains controversial. Here we present the
+results of detailed studies of specific heat, magnetic and dielectric
+properties of Bi$_2$CuO$_4$ single crystals grown by the floating zone
+technique, combined with the polarized neutron scattering and high-resolution
+X-ray measurements. Our polarized neutron scattering data show Cu spins are
+parallel to the $ab$ plane. Below the onset of the long range antiferromagnetic
+ordering we observe an electric polarization induced by an applied magnetic
+field, which indicates inversion symmetry breaking by the ordered state of Cu
+spins. For the magnetic field applied perpendicular to the tetragonal axis, the
+spin-induced ferroelectricity is explained in terms of the linear
+magnetoelectric effect that occurs in a metastable magnetic state. A relatively
+small electric polarization induced by the field parallel to the tetragonal
+axis may indicate a more complex magnetic ordering in Bi$_2$CuO$_4$.",1703.02069v1
+2018-02-27,Low lying magnetic states of the mixed valence cobalt ludwigite,"There are two interpretations offered for the different structural and
+magnetic properties of the mixed valence homo-metallic ludwigites, Co3O2BO3 and
+Fe3O2BO3. One of them associates the physical behavior to charge ordering
+processes among the cations, as is well known in simpler oxides. The other
+attributes the effects to local pairwise magnetic interactions. Recently first
+principles calculations in the iron ludwigite have shown that the structural
+cation dimerization is due to the formation of strong magnetic dyads supporting
+the second model. Here we confirm the dominance of magnetic interactions to
+explain the absence of dimerization in the cobalt compound. Density functional
+non-collinear spin calculations are carried out on Co3O2BO3 to determine its
+low temperature magnetic order. Low spin is found on tri-valent cobalt sites,
+thus preventing the formation of the ferromagnetic dyad, the mechanism which
+favors dimerization in Fe3O2BO3. We conclude that the difference between high
+spin Fe3+ and low spin Co3+ pairwise interactions is responsible for the
+observed differences between the two compounds. The pairwise magnetic
+interactions also explain the difference between the existence of low
+temperature bulk AF state in the Fe ludwigite and its absence in the Co
+material.",1802.10063v2
+2018-11-12,Site selective spin and orbital excitations in Fe3O4,"$Fe_3O_4$ is a mixed-valence strongly correlated transition metal oxide which
+displays the intriguing metal to insulator Verwey transition. Here we
+investigate the electronic and magnetic structure of $Fe_3O_4$ by a unique
+combination of high-resolution Fe 2p3d resonant inelastic scattering magnetic
+circular (RIXS-MCD) and magnetic linear (RIXS-MLD) dichroism. We show that by
+coupling the site selectivity of RIXS with the magnetic selectivity imposed by
+the incident polarization handedness, we can unambiguously identify spin-flip
+excitations and quantify the exchange interaction of the different sublattices.
+Furthermore, our RIXS-MLD measurements show spin-orbital excitations that
+exhibit strong polarization and magnetic field dependence. Guided by
+theoretical simulations, we reveal that the angular dependence arises from a
+strong interplay between trigonal crystal-field, magnetic exchange and
+spin-orbit interaction at the nominal $Fe^{2+}$ sites. Our results highlight
+the capabilities of RIXS magnetic dichroism studies to investigate the ground
+state of complex systems where in-equivalent sites and bonds are simultaneously
+present.",1811.04836v1
+2019-05-07,Modulation of magnetism via electric field in MgO nanoribbons,"We report on a theoretical study of electromagnetic properties of zigzag
+magnesium oxides nanoribbons (Z-MgONRs). We propose that the polar charges and
+the spin polarization are the two key factors for edge magnetism. Based on
+first-principle calculations, we demonstrate that both O- and Mg-edges are
+magnetic and their magnetic moments all can be efficiently modulated via
+external electric field.And the edge magnetism is further studied in the
+framework of effective tight-binding model, which provides a starting point for
+the calculation of one particle Green's function and the determination of
+exchange interactions. Utilizing the linear response model, we find that
+Z-MgONRs exhibit two kinds of exchange interaction with extremely different
+natures. The magnetism in O-edge is strongly localized with ferromagnetic order
+while the magnetism in Mg-edge is itinerant with Ruderman-Kittel-Kasuya-Yosida
+(RKKY) like interactions. And these two couplings can also be modulated by
+electric field, giving rise to the electrical modulations of spin-density-wave
+(SDW) and the modulation of Curie temperature in O-edge. All these suggest that
+Z-MgONRs are ideal platforms for ME coupling and appealing candidates for
+manifold applications.",1905.02328v1
+2017-04-24,Interface magnetism and electronic structure: ZnO(0001)/Co3O4(111),"We have studied the structural, electronic and magnetic properties of spinel
+$\rm Co_3O_4$(111) surfaces and their interfaces with ZnO (0001) using density
+functional theory (DFT) within the Generalized Gradient Approximation with
+on-site Coulomb repulsion term (GGA+U). Two possible forms of spinel surface,
+containing $\rm Co^{2+} $ and $\rm Co^{3+} $ ions and terminated with either
+cobalt or oxygen ions were considered, as well as their interface with zinc
+oxide. Our calculations demonstrate that $\rm Co^{3+} $ ions attain non-zero
+magnetic moments at the surface and interface, in contrast to the bulk, where
+they are not magnetic, leading to the ferromagnetic ordering. Since heavily
+Co-doped ZnO samples can contain $\rm Co_3O_4 $ secondary phase, such a
+magnetic ordering at the interface might explain the origin of the magnetism in
+these diluted magnetic semiconductors (DMS).",1704.07148v4
+2017-04-26,Magnetic Force Microscopy for Nanoparticle Characterization,"Since the invention of the atomic force microscope (AFM) in 1986, there has
+been a drive to apply this scanning probe technique or a form of this technique
+to various disciplines in nanoscale science. Magnetic force microscopy (MFM) is
+a member of a growing family of scanning probe methods and has been widely used
+for the study of magnetic materials. In MFM a magnetic probe is used to
+raster-scan the surface of the sample, of which its magnetic field interacts
+with the magnetic tip to offer insight into its magnetic properties. This
+review will focus on the use of MFM in relation to nanoparticle
+characterization, including superparamagnetic iron oxide nanoparticles,
+covering MFM imaging in air and in liquid environments.",1704.08289v1
+2015-12-01,Epitaxial patterning of nanometer-thick Y3Fe5O12 films with low magnetic damping,"Magnetic insulators such as yttrium iron garnet, Y3Fe5O12, with extremely low
+magnetic damping have opened the door for low power spin-orbitronics due to
+their low energy dissipation and efficient spin current generation and
+transmission. We demonstrate reliable and efficient epitaxial growth and
+nanopatterning of Y3Fe5O12 thin-film based nanostructures on insulating
+Gd3Ga5O12 substrates. In particular, our fabrication process is compatible with
+conventional sputtering and liftoff, and does not require aggressive ion
+milling which may be detrimental to the oxide thin films. Structural and
+magnetic properties indicate good qualities, in particular low magnetic damping
+of both films and patterned structures. The dynamic magnetic properties of the
+nanostructures are systematically investigated as a function of the lateral
+dimension. By comparing to ferromagnetic nanowire structures, a distinct edge
+mode in addition to the main mode is identified by both experiments and
+simulations, which also exhbits cross-over with the main mode upon varying the
+width of the wires. The non-linear evolution of dynamic modes over
+nanostructural dimensions highlights the important role of size confinement to
+their material properties in magnetic devices where Y3Fe5O12 nanostructures
+serve as the key functional component.",1512.00286v1
+2015-12-08,Development of magnetic liquid metal suspensions for magnetohydrodynamics,"A new class of materials is developed that is a liquid with both high
+conductivity and magnetic susceptibility for magnetohydrodynamic (MHD)
+applications. We develop a general method for making such suspensions and
+demonstrate that various magnetic and non-magnetic metal particles, from 40 nm
+- 500 microns in diameter, can be suspended in liquid gallium and its alloys.
+The method uses an acid solution to prevent oxidation of the liquid metal and
+metallic particles, which allows wetting and thus suspending. We can increase
+the magnetic permeability by a factor of 5.0 by controlling the packing
+fraction of magnetic particles, which gives these materials the potential to
+exhibit strong MHD effects on the laboratory scale that are usually only
+observable in the cores of planets and stars. We can independently tune the
+viscosity by a factor of 230 by adding non-magnetic particles, which would
+allow independent control of MHD effects from turbulence.",1512.02575v4
+2020-01-07,Growth-sequence-dependent interface magnetism of SrIrO$_3$ - La$_{0.7}$Sr$_{0.3}$MnO$_3$ bilayers,"Bilayers of the oxide 3d ferromagnet La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ (LSMO) and
+the 5d paramagnet SrIrO$_{3}$ (SIO) with large spin-orbit coupling (SOC) have
+been investigated regarding the impact of interfacial SOC on magnetic order.
+For the growth sequence of LSMO on SIO, ferromagnetism is strongly altered and
+large out-of-plane-canted anisotropy associated with lacking magnetic
+saturation up to 4 T has been observed. Thin bilayer films have been grown
+coherently in both growth sequences on SrTiO$_3$ (001) by pulsed laser
+deposition and structurally characterized by scanning transmission electron
+microscopy (STEM) and x-ray diffraction (XRD). Measurements of magnetization
+and field-dependent Mn L$_{2,3}$ edge x-ray magnetic circular dichroism (XMCD)
+reveal changes of LSMO magnetic order which are strong in LSMO on SIO and weak
+in LSMO underneath of SIO. We attribute the impact of the growth sequence to
+the interfacial lattice structure/symmetry which is known to influence the
+interfacial magnetic coupling.",2001.02083v1
+2017-09-25,"The structural, magnetic and optical properties of TMn@(ZnO)42 (TM = Fe, Co and Ni) hetero-nanostructure","The magnetic transition-metal (TM) @ oxide nanoparticles have been of great
+interest due to their wide range of applications, from medical sensors in
+magnetic resonance imaging to photo-catalysis. Although several studies on
+small clusters of TM@oxide have been reported, the understanding of the
+physical electronic properties of TMn@(ZnO)42 is far from sufficient. In this
+work, the electronic, magnetic and optical properties of TMn@(ZnO)42 (TM = Fe,
+Co and Ni) hetero-nanostructure are investigated using the density functional
+theory (DFT). It has been found that the core-shell nanostructure Fe13@(ZnO)42,
+Co15@(ZnO)42 and Ni15@(ZnO)42 are the most stable structures. Moreover, it is
+also predicted that the variation of the magnetic moment and magnetism of Fe,
+Co and Ni in TMn@ZnO42 hetero-nanostructure mainly stems from effective
+hybridization between core TM-3d orbitals and shell O-2p orbitals, and a
+magnetic moment inversion for Fe15@(ZnO)42 is investigated. Finally, optical
+properties studied by calculations show a red shift phenomenon in the
+absorption spectrum compared with the case of (ZnO)48.",1709.08502v1
+2019-04-18,Suppression of long range magnetic ordering and electrical conduction in Y$_{1.7}$Bi$_{0.3}$Ir$_2$O$_7$ thin film,"We find that the long-range magnetic ordering is absent and electrical
+conduction suppressed in Y$_{1.7}$Bi$_{0.3}$Ir$_2$O$_7$/YSZ(100) thin film
+prepared by pulsed laser deposition. The sharp down-turn of inverse magnetic
+susceptibility X-1(T) from the conventional Curie-Weiss behaviour below T* ~
+168K suggests an inhomogeneous ferromagnetic Griffiths like phase. The
+transport and magnetic properties are explained on the basis of the coexistence
+of mixed oxidation states of Ir, (i.e. Ir4+ and Ir3+) leading to non-magnetic
+defects and reduction in t2g density of states at the Fermi level.",1904.08615v1
+2020-10-14,Interface-driven magnetic anisotropy in relaxed La$_{0.7}$Sr$_{0.3}$CrO$_3$/La$_{0.7}$Sr$_{0.3}$MnO$_3$ heterostructures on MgO,"We investigate the structural and magnetic properties of
+La$_{0.7}$Sr$_{0.3}$CrO$_3$ (LSCO)/La$_{0.7}$Sr$_{0.3}$MnO$_3$(LSMO)
+heterostructures grown on (001)-oriented MgO by molecular beam epitaxy. Due to
+the large film-substrate lattice mismatch, strain relaxation is found to occur
+within the first 2-3 unit cells (uc) of the film as evidenced by reflection
+high energy electron diffraction and high-resolution synchrotron X-ray
+reciprocal space mapping. We find that the presence of the LSCO spacer and
+capping layers leads to ferromagnetism in ultra-thin LSMO layers with
+thicknesses on the order of 2 uc with the magnetic easy axis oriented in the
+film plane. Net magnetic moments of 1.4 and 2.4 $\mu_B$/Mn are measured for [2
+uc LSCO/ 2 uc LSMO] and [2 uc LSCO/ 4 uc LSMO] superlattices, respectively by
+SQUID magnetometry. The effective magnetic anisotropy of the relaxed [2 uc
+LSCO/ 4 uc LSMO] heterostructure is found to be an order of magnitude higher
+than bulk LSMO highlighting the critical role of interfacial magnetic exchange
+interactions in tuning magnetic anisotropy at complex oxide interfaces.",2010.07180v1
+2021-05-25,Dynamics of particles with cubic magnetic anisotropy in a viscous liquid,"The specific absorption rate (SAR) of a dilute assembly of spherical iron
+nanoparticles with cubic anisotropy distributed in a viscous liquid is
+calculated using the solution of stochastic Landau - Lifshitz equation for unit
+magnetization vector and stochastic equations for multiple particle directors
+that specify the spatial orientation of the nanoparticle in a liquid. The
+viscous and magnetic magnetization reversal modes of particles are revealed at
+low and sufficiently high amplitudes of alternating magnetic field,
+respectively. The SAR of iron nanoparticle assembly is shown to exceed
+significantly that of iron oxide nanoparticles with uniaxial anisotropy at the
+same amplitudes and frequencies of applied magnetic field. The linear response
+theory is shown to be valid only at small magnetic field amplitudes, H0 < 50 -
+70 Oe.",2105.11916v1
+2021-07-21,Radical pairs can explain magnetic field and lithium effects on the circadian clock,"Drosophila's circadian clock can be perturbed by magnetic fields, as well as
+by lithium administration. Cryptochromes are critical for the circadian clock.
+Further, the radical pairs in cryptochrome also can explain magnetoreception in
+animals. Based on a simple radical pair mechanism model of the animal magnetic
+compass, we show that both magnetic fields and lithium can influence the spin
+dynamics of the naturally occurring radical pairs and hence modulate the
+circadian clock's rhythms. Using a simple chemical oscillator model for the
+circadian clock, we show that the spin dynamics influence a rate in the
+chemical oscillator model, which translates into a change in the circadian
+period. Our model can reproduce the results of two independent experiments,
+magnetic fields and lithium effects on the circadian clock. Our model predicts
+that stronger magnetic fields would shorten the clock's period. We also predict
+that lithium influences the clock in an isotope-dependent manner. Furthermore,
+our model also predicts that magnetic fields and hyperfine interactions
+modulate oxidative stress. The findings of this work suggest that quantum
+nature and entanglement of radical pairs might play roles in the brain, as
+another piece of evidence in addition to recent results on xenon anesthesia and
+lithium effects on hyperactivity.",2107.10677v1
+2021-08-14,Voltage-controlled magnetism enabled by resistive switching,"The discovery of new mechanisms of controlling magnetic properties by
+electric fields or currents furthers the fundamental understanding of magnetism
+and has important implications for practical use. Here, we present a novel
+approach of utilizing resistive switching to control magnetic anisotropy. We
+study a ferromagnetic oxide that exhibits an electrically triggered
+metal-to-insulator phase transition producing a volatile resistive switching.
+This switching occurs in a characteristic spatial pattern: the formation of a
+transverse insulating barrier inside a metallic matrix resulting in an unusual
+ferromagnetic/paramagnetic/ferromagnetic configuration. We found that the
+formation of this voltage-driven paramagnetic insulating barrier is accompanied
+by the emergence of a strong uniaxial magnetic anisotropy that overpowers the
+intrinsic material anisotropy. Our results demonstrate that resistive switching
+is an effective tool for manipulating magnetic properties. Because resistive
+switching can be induced in a very broad range of materials, our findings could
+enable a new class of voltage-controlled magnetism systems.",2108.06445v1
+2021-09-16,Oxygen vacancy-induced anomalous Hall effect in a nominally non-magnetic oxide,"The anomalous Hall effect, a hallmark of broken time-reversal symmetry and
+spin-orbit coupling, is frequently observed in magnetically polarized systems.
+Its realization in non-magnetic systems, however, remains elusive. Here, we
+report on the observation of anomalous Hall effect in nominally non-magnetic
+KTaO3. Anomalous Hall effect emerges in reduced KTaO3 and shows an extrinsic to
+intrinsic crossover. A paramagnetic behavior is observed in reduced samples
+using first principles calculations and quantitative magnetometry. The observed
+anomalous Hall effect follows the oxygen vacancy-induced magnetization
+response, suggesting that the localized magnetic moments of the oxygen
+vacancies scatter conduction electrons asymmetrically and give rise to
+anomalous Hall effect. The anomalous Hall conductivity becomes insensitive to
+scattering rate in the low temperature limit (T<5 K), implying that the Berry
+curvature of the electrons on the Fermi surface controls the anomalous Hall
+effect. Our observations describe a detailed picture of many-body interactions,
+triggering anomalous Hall effect in a non-magnetic system.",2109.08073v2
+2022-05-10,"Structural, electronic and magnetic properties of La$_{1.5}$Ca$_{0.5}$(Co$_{0.5}$Fe$_{0.5}$)IrO$_6$ double perovskite","In this work, we report the synthesis and investigation of structural,
+electronic, and magnetic properties of
+La$_{1.5}$Ca$_{0.5}$(Co$_{0.5}$Fe$_{0.5}$)IrO$_6$. Our polycrystalline sample
+forms as a single-phase double perovskite in monoclinic $P2_{1}/n$ space group.
+Co and Ir are most likely in bivalent and tetravalent oxidation states,
+respectively, while Mossbauer spectroscopy indicates that Fe is in a trivalent
+state. The ac and dc magnetization data suggest a ferrimagnetic behavior
+resulting from the presence of two antiferromagnetic sublattices at Co/Fe and
+Ir sites. The large coercive field H_C $\simeq$ 32 kOe observed at 10 K,
+comparable to that of other double perovskites of interest for hard magnets, is
+discussed in terms of the structural distortion and the spin and orbital
+magnetic moments of the transition metal ions.",2205.04778v1
+2022-06-30,Strain engineering of the magnetic anisotropy and magnetic moment in NdFeO3 epitaxial thin films,"Strain engineering is a powerful mean for tuning the various functionalities
+of ABO3 perovskite oxide thin films. Rare-earth orthoferrite RFeO3 materials
+such as NdFeO3 (NFO) are of prime interest because of their intriguing magnetic
+properties as well as their technological potential applications especially as
+thin films. Here, using a large set of complementary and advanced techniques,
+we show that NFO epitaxial thin films, successfully grown by pulsed laser
+deposition on (001)-SrTiO3, show a strong magnetic anisotropy below a critical
+thickness tc of 54 nm, associated with the occurrence of structural
+modifications related to symmetry and domain pattern changes. By varying the
+tensile misfit strain through the decrease of film thickness below tc, the
+amplitudes of in and out-of-plane magnetization can be continuously tuned while
+their ratio stays constant. Furthermore, different low-temperature magnetic
+behaviors are evidenced for strained and relaxed films, suggesting that the
+strain-induced structural state impacts the magnetic phase stability.",2206.15071v1
+2023-03-29,Magnetic Anisotropy and Its Structural Origins in Ru-Substituted Manganite Films,"Controlling magnetic anisotropy (MA) is important in a variety of
+applications including magnetic memories, spintronic sensors, and
+skyrmion-based data distribution. The perovskite manganite family provides a
+fertile playground for complex, intricate, and potentially useful
+structure-magnetism relations. Here we report on the MA that emerges in 10% Ru
+substituted $La_{0.7}Sr_{0.3}MnO_{3}$ (Ru-LSMO) films for which strong
+perpendicular magnetization and anisotropic in-plane magnetization are found.
+These moderately compressively strained films possess a rich microstructure,
+consisting of coherently strained phase which evolves into a one dimensional
+(1D) periodically-modulated structure above a critical thickness. We illustrate
+how 10% Ru substitution plays a crucial role behind the observed MA, and how
+the structural distortion and 1D periodic structural modulation produce the
+anisotropic in-plane magnetization. We highlight the practical significance of
+the observed MA, which could pave the way towards the realization of
+cutting-edge oxide-based room temperature spintronic memory devices.",2303.17008v2
+2023-04-27,"Room Temperature Ferrimagnetism, Magnetodielectric and Exchange Bias Effect in CoFeRhO$_4$","Geometrically frustrated structures combined with competing exchange
+interactions that have different magnitudes are known ingredients for achieving
+exotic properties. Herein, we studied detailed structural, magnetic, thermal
+(specific heat), magneto-dielectric, and magnetic exchange bias properties of a
+mixed 3d - 4d spinel oxide with composition CoFeRhO$_4$. Detailed
+magnetization, heat capacity, and neutron powder diffraction studies (NPD)
+highlight long-range ferrimagnetic ordering with an onset at 355 K. The
+magnetic structure is established using a ferrimagnetic model (collinear-type)
+that has a propagation vector k = 0, 0, 0. The magneto-dielectric effect
+appears below the magnetic ordering temperature, and the exchange bias (EB)
+effect is observed in field cooled (FC) conditions below 355 K. The
+magneto-dielectric coupling in CoFeRhO$_4$ originates due to the frustration in
+the structure, collinear ferrimagnetic ordering, and uncompensated magnetic
+moments. The unidirectional anisotropy resulting from the uncompensated
+magnetic moments causes the room-temperature exchange bias effect. Remarkably,
+the appearance of technologically important properties (ferromagnetism,
+magnetodielectric effect, and EB) at room temperature in CoFeRhO$_4$ indicates
+its potential use in sensors or spintronics.",2304.13983v1
+2023-09-12,Probing spatial variation of magnetic order in strained SrMnO$_3$ thin films using Spin Hall Magnetoresistance,"SrMnO$_{3}$ (SMO) is a magnetic insulator and predicted to exhibit a
+multiferroic phase upon straining. Strained films of SMO display a wide range
+of magnetic orders, ranging from G-type to C-and A-type, indicative of
+competing magnetic interactions. The potential of spin Hall magnetoresistance
+(SMR) is exploited as an electrical probe for detecting surface magnetic order,
+to read surface magnetic moments in SMO and its spatial variation, by designing
+and positioning electrodes of different sizes on the film. The findings
+demonstrate antiferromagnetic domains with different magnetocrystalline
+anisotropies along with a ferromagnetic order, where the magnetization arises
+from double exchange mediated ferromagnetic order and canted antiferromagnetic
+moments. Further, from a complete analysis of the SMR, a predominance of
+antiferromagnetic domain sizes of 3.5 $\mu$m$^2$ is extracted. This work
+enhances the applicability of SMR in unraveling the richness of correlation
+effects in complex oxides, as manifested by the detection of coexisting and
+competing ground states and lays the foundation for the study of magnon
+transport for different magnetoelectric based computing applications.",2309.06279v1
+2023-10-02,Adiabatic demagnetization refrigeration to mK temperatures with the distorted square lattice magnet NaYbGeO$_{4}$,"We report the synthesis, characterization, low-temperature magnetic, and
+thermodynamic measurements of the novel milli-Kelvin adiabatic demagnetization
+refrigeration (mK-ADR) candidate material NaYbGeO$_4$ which exhibits a
+distorted square lattice arrangement of YbO$_{6}$ magnetic units. Magnetization
+and specific heat indicate weakly interacting effective spin-1/2 moments below
+10~K, with a Curie-Weiss temperature of only 15~mK, that can be polarized by
+magnetic fields of order 1~T. For the ADR performance test, we start the
+demagnetization from 5~T at a temperature of $\sim 2$~K and reach a minimum
+temperature of 150~mK at zero field. The warming curve indicates a sharp
+magnetic transition in the heat capacity at 210~mK, implying only weak magnetic
+frustration. The entropy density of $S_{\rm GS}\simeq 101$ mJ K$
+^{-1}$cm$^{-3}$ and hold time below 2~K of 220~min are competitive while the
+minimal temperature is higher compared to frustrated Ytterbium-oxide ADR
+materials studied under similar conditions.",2310.00961v1
+2023-12-17,Magnetic Fluctuations in Niobium Pentoxide,"Using a spin-polarized muon beam we were able to capture magnetic dynamics in
+an amorphous niobium pentoxide thin film. Muons are used to probe internal
+magnetic fields produced by defects. Magnetic fluctuations could be described
+by the dynamical Kubo-Toyabe model considering a time-dependent local magnetic
+field. We state that observed fluctuations result from the correlated motion of
+electron spins. We expect that oxygen vacancies play a significant role in
+these films and lead to a complex magnetic field distribution which is
+non-stationary. The characteristic average rate of magnetic field change is on
+the order of 100~MHz. The observed dynamics may provide insight into potential
+noise sources in Nb-based superconducting devices, while also highlighting the
+limitations imposed by amorphous oxides.",2312.10697v1
+2024-03-01,Cooperatively Modulating Magnetic Anisotropy and Colossal Magnetoresistance via Atomic-Scale Buffer Layers in Highly Strained La0.7Sr0.3MnO3 Films,"Simultaneous control of magnetic anisotropy and magnetoresistance, especially
+with atomic scale precision, remains a pivotal challenge for realizing advanced
+spintronic functionalities. Here we demonstrate cooperative continuous control
+over both magnetoresistance and magnetic anisotropy in highly strained
+La0.7Sr0.3MnO3 (LSMO) thin films. By inserting varying perovskite buffer
+layers, compressively strained LSMO films transition from a ferromagnetic
+insulator with out-of-plane magnetic anisotropy to a metallic state with
+in-plane anisotropy. Atomic-scale buffer layer insertion enables remarkably
+acute, precise control to sharply modulate this magnetic phase transformation.
+A gigantic 10,000% modulation of the colossal magnetoresistance (CMR) and an
+exceptionally sharp transition from out-of-plane to in-plane magnetic
+anisotropy are attained in just a few contiguous layers. These atomic-scale
+correlations among electronic, magnetic, and structural order parameters yield
+flexible multifunctional control promising for next-generation oxide
+spintronics.",2403.00361v1
+1998-12-01,"Synthesis, Characterization and Magnetic Susceptibility of the Heavy Fermion Transition Metal Oxide LiV_{2}O_{4}","The preparative method, characterization and magnetic susceptibility \chi
+measurements versus temperature T of the heavy fermion transition metal oxide
+LiV_{2}O_{4} are reported in detail. The intrinsic \chi(T) shows a nearly
+T-independent behavior below ~ 30 K with a shallow broad maximum at about 16 K,
+whereas Curie-Weiss-like behavior is observed above 50-100 K. Field-cooled and
+zero-field-cooled magnetization M measurements in applied magnetic fields H =
+10 to 100 G from 1.8 to 50 K showed no evidence for spin-glass ordering.
+Crystalline electric field theory for an assumed cubic V point group symmetry
+is found insufficient to describe the observed temperature variation of the
+effective magnetic moment. The Kondo and Coqblin-Schrieffer models do not
+describe the magnitude and T dependence of \chi with realistic parameters. In
+the high T range, fits of \chi(T) by the predictions of high temperature series
+expansion calculations provide estimates of the V-V antiferromagnetic exchange
+coupling constant J/k_{B} ~ 20 K, g-factor g ~ 2 and the T-independent
+susceptibility. Other possible models to describe the \chi(T) are discussed.
+The paramagnetic impurities in the samples were characterized using isothermal
+M(H) measurements with 0 < H <= 5.5 Tesla at 2 to 6 K. These impurities are
+inferred to have spin S_{imp} ~ 3/2 to 4, g_{imp} ~ 2 and molar concentrations
+of 0.01 to 0.8 %, depending on the sample.",9812020v1
+2006-01-17,Fingerprints of spin-orbital physics in cubic Mott insulators: Magnetic exchange interactions and optical spectral weights,"The temperature dependence and anisotropy of optical spectral weights
+associated with different multiplet transitions is determined by the spin and
+orbital correlations. To provide a systematic basis to exploit this close
+relationship between magnetism and optical spectra, we present and analyze the
+spin-orbital superexchange models for a series of representative
+orbital-degenerate transition metal oxides with different multiplet structure.
+For each case we derive the magnetic exchange constants, which determine the
+spin wave dispersions, as well as the partial optical sum rules. The magnetic
+and optical properties of early transition metal oxides with degenerate
+$t_{2g}$ orbitals (titanates and vanadates with perovskite structure) are shown
+to depend only on two parameters, viz. the superexchange energy $J$ and the
+ratio $\eta$ of Hund's exchange to the intraorbital Coulomb interaction, and on
+the actual orbital state. In $e_g$ systems important corrections follow from
+charge transfer excitations, and we show that KCuF$_3$ can be classified as a
+charge transfer insulator, while LaMnO$_3$ is a Mott insulator with moderate
+charge transfer contributions. In some cases orbital fluctuations are quenched
+and decoupling of spin and orbital degrees of freedom with static orbital order
+gives satisfactory results for the optical weights. On the example of cubic
+vanadates we describe a case where the full quantum spin-orbital physics must
+be considered. Thus information on optical excitations, their energies,
+temperature dependence and anisotropy, combined with the results of magnetic
+neutron scattering experiments, provides an important consistency test of the
+spin-orbital models, and indicates whether orbital and/or spin fluctuations are
+important in a given compound.",0601381v1
+2010-09-03,Magnetic and transport properties of the spin-state disordered oxide La0.8Sr0.2Co_{1-x}Rh_xO_{3-δ},"We report measurements and analysis of magnetization, resistivity and
+thermopower of polycrystalline samples of the perovskite-type Co/Rh oxide
+La$_{0.8}$Sr$_{0.2}$Co$_{1-x}$Rh$_x$O$_{3-\delta}$. This system constitutes a
+solid solution for a full range of $x$,in which the crystal structure changes
+from rhombohedral to orthorhombic symmetry with increasing Rh content $x$. The
+magnetization data reveal that the magnetic ground state immediately changes
+upon Rh substitution from ferromagnetic to paramagnetic with increasing $x$
+near 0.25, which is close to the structural phase boundary. We find that one
+substituted Rh ion diminishes the saturation moment by 9 $\mu_B$, which implies
+that one Rh$^{3+}$ ion makes a few magnetic Co$^{3+}$ ions nonmagnetic (the low
+spin state), and causes disorder in the spin state and the highest occupied
+orbital. In this disordered composition ($0.05\le x \le 0.75$), we find that
+the thermopower is anomalously enhanced below 50 K. In particular, the
+thermopower of $x$=0.5 is larger by a factor of 10 than those of $x$=0 and 1,
+and the temperature coefficient reaches 4 $\mu$V/K$^2$ which is as large as
+that of heavy-fermion materials such as CeRu$_2$Si$_2$.",1009.0728v2
+2010-11-23,Quantum fluctuations in the effective pseudospin-1/2 model for magnetic pyrochlore oxides,"The effective quantum pseudospin-1/2 model for interacting rare-earth
+magnetic moments, which are locally described with atomic doublets, is studied
+theoretically for magnetic pyrochlore oxides. It is derived microscopically for
+localized Pr^{3+} 4f moments in Pr_2TM_2O_7 (TM = Zr, Sn, Hf, and Ir) by
+starting from the atomic non-Kramers magnetic doublets and performing the
+strong-coupling perturbation expansion of the virtual electron transfer between
+the Pr 4f and O 2p electrons. The most generic form of the nearest-neighbor
+anisotropic superexchange pseudospin-1/2 Hamiltonian is also constructed from
+the symmetry properties, which is applicable to Kramers ions Nd^{3+}, Sm^{3+},
+and Yb^{3+} potentially showing large quantum effects. The effective model is
+then studied by means of a classical mean-field theory and the exact
+diagonalization on a single tetrahedron and on a 16-site cluster. These
+calculations reveal appreciable quantum fluctuations leading to quantum phase
+transitions to a quadrupolar state as a melting of spin ice for the Pr^{3+}
+case. The model also shows a formation of cooperative quadrupole moment and
+pseudospin chirality on tetrahedrons. A sign of a singlet quantum spin ice is
+also found in a finite region in the space of coupling constants. The relevance
+to the experiments is discussed.",1011.4981v2
+2012-12-07,Magneto-optic Faraday effect in maghemite nanoparticles/silica matrix nanocomposites prepared by the Sol-Gel method,"Bulk monolithic samples of {\gamma}-Fe2O3/SiO2 composites with different iron
+oxide/silica ratios have been prepared by the sol-gel technique. Iron oxide
+nanoparticles are obtained in-situ during heat treatment of samples and silica
+matrix consolidation. Preparation method was previously optimized to minimize
+the percentage of antiferromagnetic {\alpha}-Fe2O3 and parallelepipeds of
+roughly 2x5x12 mm3, with good mechanical stability, are obtained. RT
+magnetization curves show a non-hysteretic behavior. Thus, magnetization
+measurements have been well fitted to an expression that combines the Langevin
+equation with an additional linear term, indicating that some of the
+nanoparticles are still superparamagnetic as confirmed by X-ray diffraction and
+electron microscopy measurements. Zero field cooled /field cooled experiments
+show curves with slightly different shapes, depending on the size and shape
+distribution of nanoparticles for a given composition. Magneto-optical Faraday
+effect measurements show that the Faraday rotation is proportional to
+magnetization of the samples, as expected. As a demonstration of their sensing
+possibilities, the relative intensity of polarized light, measured at 5{\deg}
+from the extinction angle, was plotted versus applied magnetic field.",1212.1690v1
+2012-12-20,The Mott State and Superconductivity in Face-Centred Cubic Structured Cs3C60: A 133Cs-Nuclear Magnetic Resonance Study under Pressure,"Over the past 20 years, fullerides have been studied as the source of
+high-transition-temperature (Tc) superconductivity except for copper oxides.
+The recent finding of the Mott insulating state right beside superconductivity
+in Cs3C60 has suggested that magnetism helps raise Tc even in fullerides as in
+heavy-fermion compounds, high-Tc copper oxides, two-dimensional organic
+conductors, and iron pnictides. Namely, one tends to think that the link
+between Mott insulator and superconductivity takes place in fullerides, which
+can give rise to the mechanism beyond the Bardeen-Cooper-Schrieffer framework.
+However, the relationship between the Mott state and the superconductivity in
+Cs3C60 is still under debate. By nuclear magnetic resonance measurements under
+pressure, we find that the magnetism and superconductivity in Cs3C60 are
+competing orders. Different from previous reports, the phase separation of
+Cs3C60 crystals into the Mott and metallic states allows us to systematically
+study the evolution of the ground state under pressure. Our careful experiments
+have found that the prevention of a magnetic order is rather essential for the
+superconductivity in face-centred cubic Cs3C60, which presents a basic strategy
+for finding still higher Tc in this system.",1212.4937v1
+2013-06-21,Evidence for Intra-Unit-Cell magnetic order in the pseudo-gap state of high-Tc cuprates,"The existence of the mysterious pseudo-gap state in the phase diagram of
+copper oxide superconductors and its interplay with unconventional {\it d-wave}
+superconductivity has been a long standing issue for more than a decade. There
+is now a growing number of experimental indications that the pseudo-gap phase
+actually corresponds to a symmetry breaking state. In his theory for cuprates,
+C. M. Varma proposes that the pseudo-gap is a new state of matter associated
+with the spontaneous appearance of circulating current loops within $\rm CuO_2$
+unit cell. This intra-unit-cell order breaks time reversal symmetry, but
+preserves lattice translation invariance. Polarized elastic neutron scattering
+measurements provide evidence for an intra-unit-cell magnetic order inside the
+pseudo-gap state. This order could be produced by the orbital-like magnetic
+moments induced by the circulating current loops. The magnetic order displays
+the same characteristic features in $\rm HgBa_2CuO_{4+\delta}$, $\rm
+YBa_2Cu_3O_{6+x}$ and $\rm Bi_2Sr_2CaCu_2O_{8+\delta}$ demonstrating that this
+genuine phase is ubiquitous of the pseudo-gap of high temperature copper oxide
+materials. We review the main properties characterizing this intra-unit-cell
+magnetic order and discuss its interplay or competition with other spin and
+charge instabilities.",1306.5124v1
+2015-05-04,Spatially resolved ultrafast magnetic dynamics launched at a complex-oxide hetero-interface,"Static strain in complex oxide heterostructures has been extensively used to
+engineer electronic and magnetic properties at equilibrium. In the same spirit,
+deformations of the crystal lattice with light may be used to achieve
+functional control across hetero-interfaces dynamically. Here, by exciting
+large amplitude infrared-active vibrations in a LaAlO3 substrate we induce
+magnetic order melting in a NdNiO3 film across a hetero-interface. Femtosecond
+Resonant Soft X-ray Diffraction is used to determine the spatial and temporal
+evolution of the magnetic disordering. We observe a magnetic melt front that
+grows from the substrate interface into the film, at a speed that suggests
+electronically driven propagation. Light control and ultrafast phase front
+propagation at hetero-interfaces may lead to new opportunities in
+optomagnetism, for example by driving domain wall motion to transport
+information across suitably designed devices.",1505.00601v1
+2015-05-29,Impact of oxygen doping and oxidation state of iron on the electronic and magnetic properties of BaFeO$_{3-δ},"We studied structural, electronic and magnetic properties of a cubic
+perovskite BaFeO$_{3-\delta}$ ($0 \le \delta \le 0.5$) within the density
+functional theory using a generalized gradient approximation and a GGA+U
+method. According to our calculations, BaFeO$_3$ in its stoichiometric cubic
+structure should be half-metallic and strongly ferromagnetic, with extremely
+high Curie temperature ($T_C$) of 700 - 900 K. However, a such estimate of
+$T_C$ disagrees with all available experiments, which report that $T_C$ of the
+BaFeO$_3$ and undoped BaFeO$_{3-\delta}$ films varies between 111 K and 235 K
+or, alternatively, that no ferromagnetic order was detected there. Fitting the
+calculated x-ray magnetic circular dichroism spectra to the experimental
+features seen for BaFeO$_3$, we concluded that the presence of oxygen vacancies
+in our model enables a good agreement. Thus, the relatively low $T_C$ measured
+in BaFeO$_3$ can be explained by oxygen vacancies intrinsically presented in
+the material. Since iron species near the O vacancy change their oxidation
+state from $4+$ to $3+$, the interaction between Fe$^{4+}$ and Fe$^{3+}$, which
+is antiferromagnetic, weakens the effective magnetic interaction in the system,
+which is predominantly ferromagnetic. With increasing $\delta$ in
+BaFeO$_{3-\delta}$, its $T_C$ decreases down to the critical value when the
+magnetic order becomes antiferromagnetic. Our calculations of the electronic
+structure of BaFeO$_{3-\delta}$ illustrate how the ferromagnetism originates
+and also how one can keep this cubic perovskite robustly ferromagnetic far
+above the room temperature.",1505.07942v1
+2019-05-24,Contrasting magnetism in isovalent layered LaSr3NiRuO4H4 and LaSrNiRuO4 due to distinct spin-orbital states,"The recently synthesized first 4d transition-metal oxide-hydride
+LaSr3NiRuO4H4 with the unusual high H:O ratio surprisingly displays no magnetic
+order down to 1.8 K. This is in sharp contrast to the similar unusual
+low-valent Ni+ - Ru2+ layered oxide LaSrNiRuO4 which has a rather high
+ferromagnetic (FM) ordering Curie temperature TC about 250 K. In this work,
+using density functional calculations with aid of crystal field level diagrams
+and superexchange pictures, we find that the contrasting magnetism is due to
+the distinct spin-orbital states of the Ru2+ ions (in addition to the common
+Ni+ S=1/2 state but with a different orbital state): the Ru2+ S=0 state in
+LaSr3NiRuO4H4, but the Ru2+ S=1 state in LaSrNiRuO4. The Ru2+ S=0 state has the
+(xy)2(xz; yz)4 occupation due to the RuH4O2 octahedral coordination, and then
+the nonmagnetic Ru2+ ions dilute the S=1/2 Ni+ sublattice which consequently
+has a very weak antiferromagnetic (AF) superexchange and thus accounts for no
+presence of magnetic order down to 1.8 K in LaSr3NiRuO4H4. In strong contrast,
+the Ru2+ S=1 state in LaSrNiRuO4 has the (3z2-r2)2(xz; yz)3(xy)1 occupation due
+to the planar square RuO4 coordination, and then the multi-orbital FM
+superexchange between the S=1/2 Ni+ and S=1 Ru2+ ions gives rise to the high TC
+in LaSrNiRuO4. This work highlights the importance of spin-orbital states in
+determining the distinct magnetism.",1905.10055v1
+2017-07-12,Polarity-tunable magnetic tunnel junctions based on ferromagnetism at oxide heterointerfaces,"Complex oxide systems have attracted considerable attention because of their
+fascinating properties, including the magnetic ordering at the conducting
+interface between two band insulators, such as LaAlO3 (LAO) and SrTiO3 (STO).
+However, the manipulation of the spin degree of freedom at the LAO/STO
+heterointerface has remained elusive. Here, we have fabricated hybrid magnetic
+tunnel junctions consisting of Co and LAO/STO ferromagnets with the insertion
+of a Ti layer in between, which clearly exhibit magnetic switching and the
+tunnelling magnetoresistance (TMR) effect below 10 K. The magnitude and the of
+the TMR are strongly dependent on the direction of the rotational magnetic
+field parallel to the LAO/STO plane, which is attributed to a strong
+Rashba-type spin orbit coupling in the LAO/STO heterostructure. Our study
+provides a further support for the existence of the macroscopic ferromagnetism
+at LAO/STO heterointerfaces and opens a novel route to realize interfacial
+spintronics devices.",1707.03509v1
+2019-06-28,Mapping different skyrmion phases in double wedges of Ta/FeCoB(tFeCoB)/Ta(tTa)Ox,"Skyrmions are chiral magnetic textures that have immense potential for
+applications in spintronic devices. However, their formation is quite
+challenging and necessitates a subtle balance of the magnetic interactions at
+play. Here, we study Ta/FeCoB/TaOx trilayer using crossed double wedges i.e.
+thickness gradients of FeCoB and of top Ta, which is subsequently oxidized
+leading to an oxidation gradient. This enabled us to observe micron-sized
+skyrmions in the vicinity of different transition regions of the sample: from
+perpendicular magnetic anisotropy to paramagnetic phase and also from
+perpendicular to in-plane magnetic anisotropy. These observations can be
+explained by the isolated bubble model taking into account the different energy
+contributions at play namely anisotropy, exchange, Dzyaloshinskii-Moriya,
+dipolar and Zeeman. We also qualitatively compare the current-induced motion of
+skyrmions obtained in different transition regions. Our study not only provides
+an effective means to form skyrmions by tuning the interfacial magnetic
+properties but also highlights the differences pertaining to the skyrmions
+observed in different transition zones, which is extremely crucial for any
+envisaged application.",1906.12271v2
+2020-01-09,"Tuning of structural phase, magnetic spin order and electrical conductivity in mechanical alloyed material of alpha-Fe2O3 and alpha-Cr2O3 oxides","Alpha-Fe2O3 and alpha-Cr2O3 has been mechanical alloyed to prepare Fe1-xCrxO3
+oxides for x = 0.2-0.8. Synchrotron X-ray diffraction and Raman spectra have
+shown inhomogeneous structure of {\alpha}-Fe2O3 and {\alpha}-Cr2O3 phases in
+as-alloyed samples. The as-alloyed samples have shown soft ferromagnetic
+properties with signature of two Morin transitions. The heat treatment of
+as-alloyed samples has homogenized structure and successfully incorporated the
+Cr atoms into the lattice sites of Fe atoms in {\alpha}-Fe2O3. The magnetic and
+electrical properties have been modified in the heat treated samples. For
+example, canted antiferromagnetic order has been appeared as an effect of heat
+treatment, irrespective of the Cr content in Fe1-xCrxO3. The magnetic field
+induced spin flop transition has been observed at a critical magnetic field
+that depends on Cr content in the system. The M\""ossbauer spectrum at room
+temperature has been fitted with two sextets. The variation of M\""ossbauer
+parameters suggest a distribution of magnetic spin order between Fe and Cr ions
+in the rhombohedral structure of Fe1-xCrxO3. The electrical conductivity,
+derived from current-voltage characteristics of the heat treated samples, has
+been enhanced by increasing Cr content in alpha-Fe2O3 structure. The
+experimental results have been explained based on the theoretical models
+available in literature.",2001.02831v1
+2017-05-25,Topological Weyl and Node-Line Semimetals in Ferromagnetic Vanadium-Phosphorous-Oxide $β$-V$_2$OPO$_4$ Compound,"We propose that the topological semimetal features can co-exist with
+ferromagnetic ground state in vanadium-phosphorous-oxide $\beta$-V$_2$OPO$_4$
+compound from first-principles calculations. In this magnetic system with
+inversion symmetry, the direction of magnetization is able to manipulate the
+symmetric protected band structures from a node-line type to a Weyl one in the
+presence of spin-orbital-coupling. The node-line semimetal phase is protected
+by the mirror symmetry with the reflection-invariant plane perpendicular to
+magnetic order. Within mirror symmetry breaking due to the magnetization along
+other directions, the gapless node-line loop will degenerate to only one pair
+of Weyl points protected by the rotational symmetry along the magnetic axis,
+which are largely separated in momentum space. Such Weyl semimetal phase
+provides a nice candidate with the minimum number of Weyl points in a condensed
+matter system. The results of surface band calculations confirm the non-trivial
+topology of this proposed compound. This findings provide a realistic candidate
+for the investigation of topological semimetals with time-reversal symmetry
+breaking, particularly towards the realization of quantum anomalous Hall effect
+in Weyl semimetals.",1705.09234v1
+2020-03-11,A two-dimensional electron gas at the (001) surface of ferromagnetic EuTiO$_{3}$(001),"Studies on oxide quasi-two dimensional electron gas (q2DEG) have been a
+playground for the discovery of novel and sometimes unexpected phenomena, like
+the reported magnetism at the surface and at the interface between LaAlO$_{3}$
+and SrTiO$_{3}$ non-magnetic materials. However, magnetism in this system is
+weak and there are evidences of a not intrinsic origin. Here, by using in-situ
+high-resolution angle resolved photoemission we demonstrate that ferromagnetic
+EuTiO$_{3}$, the magnetic counterpart of SrTiO$_{3}$ in the bulk, hosts a q2DEG
+at its (001) surface. This is confirmed by density functional theory
+calculations with Hubbard U terms in the presence of oxygen divacancies in
+various configurations, all of them leading to a spin-polarized q2DEG related
+to the ferromagnetic order of Eu-4f magnetic moments. The results suggest
+EuTiO$_{3}$(001) as a new material platform for oxide q2DEGs, characterized by
+broken inversion and time reversal symmetries.",2003.05494v2
+2020-05-05,Fast magneto-ionic switching of interface anisotropy using yttria-stabilized zirconia gate oxide,"Voltage control of interfacial magnetism has been greatly highlighted in
+spintronics research for many years, as it might enable ultra-low power
+technologies. Among few suggested approaches, magneto-ionic control of
+magnetism has demonstrated large modulation of magnetic anisotropy. Moreover,
+the recent demonstration of magneto-ionic devices using hydrogen ions presented
+relatively fast magnetization toggle switching, tsw ~ 100 ms, at room
+temperature. However, the operation speed may need to be significantly improved
+to be used for modern electronic devices. Here, we demonstrate that the speed
+of proton-induced magnetization toggle switching largely depends on
+proton-conducting oxides. We achieve ~1 ms reliable (> 103 cycles) switching
+using yttria-stabilized zirconia (YSZ), which is ~ 100 times faster than the
+state-of-the-art magneto-ionic devices reported to date at room temperature.
+Our results suggest further engineering of the proton-conducting materials
+could bring substantial improvement that may enable new low-power computing
+scheme based on magneto-ionics.",2005.02005v1
+2021-05-10,Spin reorientation in tetragonally distorted spinel oxide NiCo$_2$O$_4$ epitaxial films,"We experimentally investigated the magnetic properties of NiCo$_2$O$_4$
+epitaxial films known to be conductive oxides with perpendicular magnetic
+anisotropy (PMA) at room temperature. Both magneto-torque and magnetization
+measurements at various temperatures provide clear experimental evidence of the
+spin reorientation transition at which the MA changes from PMA to easy-cone
+magnetic anisotropy (ECMA) at a certain temperature ($T_{\rm{SR}}$). ECMA was
+commonly observed in films grown by pulsed laser deposition and reactive radio
+frequency magnetron sputtering, although $T_{\mathrm{SR}}$ is dependent on the
+growth method as well as the conditions. The cone angles measured from the
+$c$-axis increased successively at $T_{\mathrm{SR}}$ and approached a maximum
+of 45-50 degrees at the lowest measurement temperature of 5 K. Calculation with
+the cluster model suggests that the Ni$^{3+}$ ions occupying the $T_d$ site
+could be the origin of the ECMA. Both the magnetic properties and the results
+of the calculation based on the cluster model indicate that the ECMA is
+attributable to the cation anti-site distribution of Ni$^{3+}$, which is
+possibly formed during the growth process of the thin films.",2105.04115v1
+2021-06-09,Intriguing Magnetoelectric Effect in Two-dimensional Ferromagnetic/Perovskite Oxide Ferroelectric Heterostructure,"Two-dimensional (2D) magnets have broad application prospects in the
+spintronics, but how to effectively control them with a small electric field is
+still an issue. Here we propose that 2D magnets can be efficiently controlled
+in a multiferroic heterostructure composed of 2D magnetic material and
+perovskite oxide ferroelectric (POF) whose dielectric polarization is easily
+flipped under a small electric field. We illustrate the feasibility of such
+strategy in the bilayer CrI3/BiFeO3(001) heterostructure by using the
+first-principles calculations. Different from the traditional POF multiferroic
+heterostructures which have strong interface interactions, we find that the
+interface interaction between CrI3 and BiFeO3(001) is van der Waals type.
+Whereas, the heterostructure has particular strong magnetoelectric coupling
+where the bilayer CrI3 can be efficiently switched between ferromagnetic and
+antiferromagnetic types by the polarized states of BiFeO3(001). We also
+discover the competing effect between electron doping and the additional
+electric field on the interlayer exchange coupling interaction of CrI3, which
+is responsible to the magnetic phase transition. Our results provide a new
+avenue for the tuning of 2D magnets with a small electric field.",2106.04998v2
+2022-10-19,"Fluorite-related iridate Pr$_3$IrO$_7$: Crystal growth, structure, magnetism, thermodynamic, and optical properties","Spin-orbit coupling in heavy 5$d$ metal oxides, in particular, iridates have
+received tremendous interest in recent years due to the realization of exotic
+electronic and magnetic phases. Here, we report the synthesis, structural,
+magnetic, thermodynamic, and optical properties of the ternary iridate
+Pr$_3$IrO$_7$. Single crystals of Pr$_3$IrO$_7$ have been grown by the KF flux
+method. Structural analysis shows that Pr$_3$IrO$_7$ crystallizes in an
+orthorhombic phase with $Cmcm$ symmetry. The electron energy loss spectroscopy
+study indicates that Pr is in a 3+ valence state, which implies a 5+ oxidation
+state of Ir. Magnetization data measured at high and low magnetic fields do not
+exhibit any bifurcation between $M_{ZFC}$ and $M_{FC}$, however, a weak hump in
+$M(T)$ is observed at $T^*$$\sim$10.4~K. The specific heat data reveal two
+maxima at $\sim$253 K and $\sim$4.8 K. The optical conductivity
+$\sigma_1(\omega)$ spectrum shows 24 infrared-active phonon modes and reveals
+an insulating behavior with an optical gap $\Delta_{OP}$ of size $\sim$500~meV.
+During cooling down, the temperature-dependent reflectivity spectrum reveals
+eight extra phonon modes below the structural phase transition ($\sim$ 253 K).
+An anomaly is observed at around $T^*$ in the temperature evolution of
+infrared-active mode frequencies suggesting the presence of significant
+spin-phonon coupling in the system.",2210.10496v1
+2023-03-27,Measuring Magnetic 1/f Noise in Superconducting Microstructures and the Fluctuation-Dissipation Theorem,"The performance of superconducting devices like qubits, SQUIDs, and particle
+detectors is often limited by finite coherence times and 1/f noise. Various
+types of slow fluctuators in the Josephson junctions and the passive parts of
+these superconducting circuits can be the cause, and devices usually suffer
+from a combination of different noise sources, which are hard to disentangle
+and therefore hard to eliminate. One contribution is magnetic 1/f noise caused
+by fluctuating magnetic moments of magnetic impurities or dangling bonds in
+superconducting inductances, surface oxides, insulating oxide layers, and
+adsorbates. In an effort to further analyze such sources of noise, we have
+developed an experimental set-up to measure both the complex impedance of
+superconducting microstructures, and the overall noise picked up by these
+structures. This allows for important sanity checks by connecting both
+quantities via the fluctuation-dissipation theorem. Since these two
+measurements are sensitive to different types of noise, we are able to identify
+and quantify individual noise sources. The superconducting inductances under
+investigation form a Wheatstone-like bridge, read out by two independent
+cross-correlated dc-SQUID read-out chains. The resulting noise resolution lies
+beneath the quantum limit of the front-end SQUIDs and lets us measure noise
+caused by just a few ppm of impurities in close-by materials. We present
+measurements of the insulating SiO2 layers of our devices, and magnetically
+doped noble metal layers in the vicinity of the pickup coils at T = 40 mK - 800
+mK and f = 1 Hz - 100 kHz.",2303.15257v2
+2023-07-25,Emergent magnetism with continuous control in the ultrahigh conductivity layered oxide PdCoO2,"The current challenge to realizing continuously tunable magnetism lies in our
+inability to systematically change properties such as valence, spin, and
+orbital degrees of freedom as well as crystallographic geometry. Here, we
+demonstrate that ferromagnetism can be externally turned on with the
+application of low-energy helium implantation and subsequently erased and
+returned to the pristine state via annealing. This high level of continuous
+control is made possible by targeting magnetic metastability in the ultra-high
+conductivity, non-magnetic layered oxide PdCoO2 where local lattice distortions
+generated by helium implantation induce emergence of a net moment on the
+surrounding transition metal octahedral sites. These highly-localized moments
+communicate through the itinerant metal states which triggers the onset of
+percolated long-range ferromagnetism. The ability to continuously tune
+competing interactions enables tailoring precise magnetic and magnetotransport
+responses in an ultra-high conductivity film and will be critical to
+applications across spintronics.",2307.13490v2
+2023-08-12,Antisymmetric Planar Hall Effect in Rutile Oxide Films Induced by the Lorentz Force,"The conventional Hall effect is linearly proportional to the field component
+or magnetization component perpendicular to a film. Despite the increasing
+theoretical proposals on the Hall effect to the in-plane field or magnetization
+in various special systems induced by the Berry curvature, such an
+unconventional Hall effect has only been experimentally reported in Weyl
+semimetals and in a heterodimensional superlattice. Here, we report an
+unambiguous experimental observation of the antisymmetric planar Hall effect
+(APHE) with respect to the in-plane magnetic field in centrosymmetric rutile
+RuO2 and IrO2 single-crystal films. The measured Hall resistivity is found to
+be linearly proportional to the component of the applied in-plane magnetic
+field along a particular crystal axis and to be independent of the current
+direction or temperature. Both the experimental observations and theoretical
+calculations confirm that the APHE in rutile oxide films is induced by the
+Lorentz force. Our findings can be generalized to ferromagnetic materials for
+the discovery of anomalous Hall effects and quantum anomalous Hall effects
+induced by in-plane magnetization. In addition to significantly expanding
+knowledge of the Hall effect, this work opens the door to explore new members
+in the Hall effect family.",2308.06651v2
+2024-01-08,Microwave-assisted synthesis of LaMnO3+d: Tuning physical properties with microwave power,"Synthesis of transition metal oxides by microwave irradiation is a faster and
+energy-saving method compared to conventional heating in an electrical furnace
+because microwave energy is directly converted into heat within precursors.
+However, not much is known about how the physical properties are modified by
+the power of microwaves. We synthesized LaMnO3+d by irradiating oxide
+precursors with microwaves and studied the impact of microwave power (P = 1000
+W, 1200 W, 1400 W and 1600 W) on magnetism, resistivity, magnetoresistance,
+thermopower, magnetic entropy change, magnetostriction, and electron spin
+resonance. It is found that paramagnetic to ferromagnetic transition becomes
+sharper, saturation magnetization increases, and electrical resistivity at low
+temperatures dramatically decreases as P increases. While the resistivity of
+samples irradiated with MW power of P less than or equal to 1400 W show
+insulating-like behavior down to 50 K, an insulator-metal transition occurs in
+the sample exposed to P = 1600 W and this sample also shows a maximum
+magnetoresistance (= -55%), magneto-thermopower (=-87%), magnetostriction (-180
+x10-6) for H = 50 kOe and magnetic entropy change of 4.78 J/kg. K for H = 30
+kOe around the Curie temperature. The intensity of electron spin resonance
+spectra at 300 K increases with P. We postulate that the much enhanced physical
+properties observed for the P = 1600 W sample arise from the creation of higher
+hole density, chemical homogeneity, and increased grain size. Our study shows
+that microwave power can be used as a knob to tune magnetism and other physical
+properties to our advantage.",2401.04087v1
+2024-02-14,Structure and magnetic properties of a La$_{0.75}$Sr$_{0.25}$Cr$_{0.90}$O$_{3-δ}$ single crystal,"We have successfully grown large and good-quality single crystals of the
+La$_{0.75}$Sr$_{0.25}$Cr$_{0.90}$O$_{3-\delta}$ compound using the
+floating-zone method with laser diodes. We investigated the crystal quality,
+crystallography, chemical composition, magnetic properties and the oxidation
+state of Cr in the grown single crystals by employing a combination of
+techniques, including X-ray Laue and powder diffraction, scanning electron
+microscopy, magnetization measurements, X-ray photoelectron spectroscopy and
+light absorption. The La$_{0.75}$Sr$_{0.25}$Cr$_{0.90}$O$_{3-\delta}$ single
+crystal exhibits a single-phase composition, crystallizing in a trigonal
+structure with the space group $R\bar{3}c$ at room temperature. The chemical
+composition was determined as La$_{0.75}$Sr$_{0.25}$Cr$_{0.90}$O$_{3-\delta}$,
+indicating a significant chromium deficiency. Upon warming, we observed five
+distinctive characteristic temperatures, namely $T_1 =$ 21.50(1) K, $T_2 =$
+34.98(1) K, $T_3 =$ 117.94(1) K, $T_4 =$ 155.01(1) K, and $T_{\textrm{N}} =$
+271.80(1) K, revealing five distinct magnetic anomalies. Our magnetization
+study allows us to explore the nature of these anomalies. Remarkably, the
+oxidation state of chromium in the single-crystal
+La$_{0.75}$Sr$_{0.25}$Cr$_{0.90}$O$_{3-\delta}$, characterized by a band gap of
+1.630(8) eV, is exclusively attributed to Cr$^{3+}$ ions, making a departure
+from the findings of previous studies on polycrystalline materials.",2402.08940v2
+1995-03-08,Screening effect of interlayer coupling on electronic transport properties of layered high-$T_c$ oxides,"We have investigated the effect of thermal fluctuation on the interlayer
+coupling of three-dimensional Josephson-junction arrays with anisotropic
+interactions as a model of layered high-$T_c$ oxides, focusing on non-Ohmic
+current-voltage characteristics. Langevin dynamic simulations were performed
+for various Josephson-coupling anisotropies and for various temperatures in
+both zero and finite magnetic fields. We find that, in the highly anisotropic
+region, the interlayer coupling, which causes the non-vanishing critical
+current ($I_{c}$), is suppressed by thermal fluctuations, and tends to push up
+the Kosterlitz-Thouless transition temperature ($T_{KT}$) of the
+two-dimensional (2D) regime. In this highly anisotropic region, $I_c$ begins to
+decrease drastically near $T_{KT}$. This suggests that interlayer coupling is
+screened by thermally excited 2D small vortex-antivortex pairs as well as the
+intralayer logarithmic part of vortex-antivortex interactions. Moreover, weak
+magnetic fields parallel to the $c$-axis affect only the
+logarithmic-interaction part between the 2D pancake vortices.",9503039v1
+1998-08-25,P-wave Pairing and Colossal Magnetoresistance in Manganese Oxides,"We point out that the existing experimental data of most manganese oxides
+show the {\sl frustrated} p-wave superconducting condensation in the
+ferromagnetic phase in the sense that the superconducting coherence is not long
+enough to cover the whole system. The superconducting state is similar to the
+$A_{1}$ state in superfluid He-3. The sharp drop of resistivity, the steep jump
+of specific heat, and the gap opening in tunneling are well understood in terms
+of the p-wave pairing. In addition, colossal magnetoresistance (CMR) is
+naturally explained by the superconducting fluctuations with increasing
+magnetic fields. The finite resistivity may be due to some magnetic
+inhomogeneities. This study leads to the possibility of room temperature
+superconductivity.",9808275v1
+1999-05-06,Role of Orbitals in Manganese Oxides - Ordering and Fluctuation,"We study the manganese oxides from the viewpoint of the strongly correlated
+doped Mott insulator. The magnetic ordering and the charge transport are
+governed by the orbital degrees of freedom, and their dimensionality is
+controlled by the anisotropic transfer integrals between the $e_g$ orbitals. As
+x increases the magnetic structure is predicted to change as $A \to F \to A \to
+C \to G$ (F: ferromagnet, A: layered antiferromagnet, C: rod-type
+antiferromagnet, G: usual antiferromagnet), in agreement with experiments.
+Especially the orbital is aligned as $d_{x^2-y^2}$ in the metallic A state,
+which explains the quasi 2D transport and no canting of the spin observed
+experimentally. Next we discuss the ferromagnetic state without the orbital
+ordering due to the quantum fluctuation. Here the interplay between the
+electron repulsion U and the Jahn-Teller electron-phonon interation $E_{LR}$ is
+studied with a large d model. In addition to this strong correlation, we
+propose that the dynamical phase separation could explain the specific heat as
+well as the various anomalous physical properties, e.g., resistivity,
+photo-emission, etc.",9905072v1
+2000-04-24,Magnetic Phase Transition of the Perovskite-type Ti Oxides,"Properties and mechanism of the magnetic phase transition of the
+perovskite-type Ti oxides, which is driven by the Ti-O-Ti bond angle
+distortion, are studied theoretically by using the effective spin and
+pseudo-spin Hamiltonian with strong Coulomb repulsion. It is shown that the
+A-type antiferromagnetic(AFM(A)) to ferromagnetic(FM) phase transition occurs
+as the Ti-O-Ti bond angle is decreased. Through this phase transition, the
+orbital state is hardly changed so that the spin-exchange coupling along the
+c-axis changes nearly continuously from positive to negative and takes
+approximately zero at the phase boundary. The resultant strong
+two-dimensionality in the spin coupling causes a rapid suppression of the
+critical temperature as is observed experimentally.",0004389v1
+2001-02-13,Magnetic and Orbital States and Their Phase Transition of the Perovskite-Type Ti Oxides: Strong Coupling Approach,"The properties and mechanism of the magnetic phase transition of the
+perovskite-type Ti oxides, which is driven by the Ti-O-Ti bond angle
+distortion, are studied theoretically by using the effective spin and
+pseudospin Hamiltonian with strong Coulomb repulsion. It is shown that the
+A-type antiferromagnetic (AFM(A)) to ferromagnetic (FM) phase transition occurs
+as the Ti-O-Ti bond angle is decreased. Through this phase transition, the
+orbital state changes only little whereas the spin-exchange coupling along the
+c-axis is expected to change from positive to negative nearly continuously and
+approaches zero at the phase boundary. The resultant strong two-dimensionality
+in the spin coupling causes rapid suppression of the critical temperature, as
+observed experimentally. It may induce large quantum fluctuations in this
+region.",0102223v1
+2002-09-11,Co-doped LaLa1-xSrxTiO3-d : A Diluted Magnetic Oxide System with High Curie Temperature,"Ferromagnetism is observed at and above room temperature in pulsed laser
+deposited epitaxial films of Co-doped Ti-based oxide perovskite
+(La1-xSrxTiO3-d). The system has the characteristics of an intrinsic diluted
+magnetic semiconductor (metal) at low concentrations (<~ 2 %), but develops
+inhomogeneity at higher cobalt concentrations. The films range from being
+opaque metallic to transparent semiconducting depending on the oxygen pressure
+during growth and are yet ferromagnetic.",0209267v3
+2002-11-27,Effect of FET geometry on charge ordering of transition metal oxides,"We examine the effect of an FET geometry on the charge ordering phase diagram
+of transition metal oxides using numerical simulations of a semiclassical model
+including long-range Coulomb fields, resulting in nanoscale pattern formation.
+We find that the phase diagram is unchanged for insulating layers thicker than
+approximately twice the magnetic correlation length. For very thin insulating
+layers, the onset of a charge clump phase is shifted to lower values of the
+strength of the magnetic dipolar interaction, and intermediate diagonal stripe
+and geometric phases can be suppressed. Our results indicate that, for
+sufficiently thick insulating layers, charge injection in an FET geometry can
+be used to experimentally probe the intrinsic charge ordering phases in these
+materials.",0211611v1
+2003-08-18,Contrasting Pathways to Mott Gap Collapse in Electron and Hole Doped Cuprates,"Recent ARPES measurements on the electron-doped cuprate Nd_{2-x}Ce_xCuO_4 can
+be interpreted in a mean field model of uniform doping of an antiferromagnet,
+with the Mott gap closing near optimal doping. Mode coupling calculations
+confirm the mean field results, while clarifying the relation between the Mott
+gap and short-range magnetic order. The same calculations find that hole doped
+cuprates should follow a strikingly different doping dependence, involving
+instability toward spiral phases or stripes. Nevertheless, the magnetic order
+(now associated with stripes) again collapses near optimal doping.",0308361v1
+2003-08-20,Two resonant magnetic modes in an overdoped high-$\bf T_c$ superconductor,"A detailed inelastic neutron scattering study of the overdoped high
+temperature copper oxide superconductor ${Y_{0.9}Ca_{0.1}Ba_{2}Cu_3O_{7}}$
+reveals two distinct magnetic resonant modes in the superconducting state. The
+modes differ in their symmetry with respect to exchange between adjacent copper
+oxide layers. Counterparts of the mode with odd symmetry, but not the one with
+even symmetry, had been observed before at lower doping levels. The observation
+of the even mode resolves a long-standing puzzle, and the spectral weight ratio
+of both modes yields an estimate of the onset of particle-hole spin-flip
+excitations.",0308394v1
+2004-06-09,Superconductivity in the insulating phase above the field-tuned superconductor-insulator transition in disordered indium oxide films,"We study the insulating phase of disordered indium oxide films that undergo a
+field-tuned superconductor-insulator transition. The transport measurements in
+a perpendicular magnetic field show distinct regimes of strongly fluctuating
+order-parameter amplitude and phase, and reveal a wide range of insulator
+strength in samples with differing disorder, despite the similarity in behavior
+near the SIT. We characterize the strength of the insulating phase and compare
+it to the superconducting strength. We find that the films do not return to the
+expected normal state even at high perpendicular magnetic fields where all
+pairs should be broken, suggesting the remaining presence of superconductivity
+at high fields.",0406227v3
+2004-08-14,Structural and Magnetic Studies on La2-xDyxCa2xBa2Cu4+2xOz Type Superconducting Oxides,"The La-2125 type La2-xDyxCa2xBa2Cu4+2xOz (0.1 < x < 0.5; LDBO) compounds have
+been synthesized and studied for their structural and superconducting
+properties by room temperature neutron diffraction, high field dc
+magnetization, four-probe resistivity and iodometric double titration. The
+Rietveld analysis of the neutron diffraction data reveals tetragonal structure
+for all the samples, which crystallizes into La-123 type tetragonal structure
+in P4/mmm space group. Iodometric double titrations were performed to determine
+the oxygen content values and calculate mobile charge carrier (holes) density.
+The superconducting transition temperatures (Tc) increases from ~ 20 K for x =
+0.1 to a maximum of 75 K for x = 0.5. Flux pinning force (Fp) and critical
+current density (Jc), calculated from the low temperature hysteresis loops,
+also increases with increasing dopant concentration. The paper presents the
+studies on structure and superconducting properties of all LDBO compounds in
+light of the role of calcium in inducing superconductivity in the tetragonal
+non-superconducting oxide.",0408334v1
+2004-09-28,Enhanced annealing effect in an oxygen atmosphere on GaMnAs,"We report on in-situ resistivity measurements on GaMnAs during post-growth
+annealing in different atmospheres. A drop in the resistivity is observed when
+the GaMnAs is exposed to oxygen, which indicates that the passivation of Mn
+interstitials (Mn_I) at the free surface occurs through oxidation. The presence
+of oxygen can therefore be an important annealing condition for the
+optimization of GaMnAs thin films, all the more since the oxidation appears to
+be limited to the sample surface. Annealing in an oxygen-free atmosphere leads
+to an increase in the resistivity indicating a second annealing mechanism
+besides the out-diffusion of Mn_I. According to our magnetization and Hall
+effect data, this mechanism reduces the amount of magnetically and electrically
+active Mn atoms.",0409720v1
+2004-12-29,"Dilute Metals: Superconductivity, Critical Currents, Magnetic Properties","Properties of oxides are interpreted as a result of existence of the virtual
+sublattices formed by the atomic quantum states. An infinite cluster with the
+superconductivity of the Bose-Einstein condensate kind can be formed in the
+ground state sublattice at certain oxigen atoms concentration in the
+effectively diluted system of metal atoms (above the percolation threshold).
+Then the electron pairs concentration n/2 can be much less than the metal atoms
+concentration N in the oxide. The similar situation takes place in metals with
+superconductivity of the BCS type. Above the percolation threshold the
+superconductivity Tc may be limited by the magnetic properties of the oxigen
+2p4quantum state sublattice. Data on the critical current density allow us to
+estimate the electronic pair density n/2 and to obtain an information
+concerning the superconductivity nature.",0412740v2
+2005-12-21,Spin-1/2 Triangular Lattice with Orbital Degeneracy in a Metallic Oxide Ag2NiO2,"A novel metallic and magnetic transition metal oxide Ag2NiO2 is studied by
+means of resistivity, magnetic susceptibility, specific heat and X-ray
+diffraction. The crystal structure is characterized by alternating stacking of
+a Ni3+O2 layer and a (Ag2)+ layer, the former realizing a spin-1/2 triangular
+lattice with eg orbital degeneracy and the latter providing itinerant
+electrons. It is found that the NiO2 layer exhibits orbital ordering at Ts =
+260 K and antiferromagnetic spin ordering at TN = 56 K. Moreover, a moderately
+large mass enhancement is found for the itinerant electrons, suggesting a
+significant contribution from the nearly localized Ni 3d state to the Ag 5s
+state that forms a broad band.",0512524v1
+2006-10-04,"Intermediate phase in the oxidative hydrothermal synthesis of potassium jarosite, a model kagome antiferromagnet","The jarosite family of minerals contain antiferromagnetically coupled Fe3+
+ions that make up the kagome network. This geometric arrangement of the Fe3+
+ions causes magnetic frustration that results in exotic electronic ground
+states, e.g. spin glasses and spin liquids. Synthesic research into jarosites
+has focused on producing near perfect stoichiometry to eliminate possible
+magnetic disorder. An new oxidative synthesis method has been devel-oped for
+the potassium, sodium, rubidium and ammonium jarosites that leads to high Fe
+coverage. We show through the identification of a meta-stable intermediate,
+using powder X-ray diffraction, how near perfect Fe coverage arises using this
+method. Understanding this new mechanism for jarosite formation suggests that
+is it possible to synthesis hydronium jarosite, an unconventional spin glass,
+with a very high Fe coverage.",0610119v1
+2007-01-26,Use of Superparamagnetic Nanoparticle/Block Copolymer Electrostatic Complexes as Contrast Agents in Magnetic Resonance Imaging,"During the past years we have investigated the complexation between
+nanocolloids and oppositely charged polymers. The nanocolloids examined were
+ionic surfactant micelles and inorganic oxide nanoparticles. For the polymers,
+we used homopolyelectrolytes and block copolymers with linear and comb
+architectures. In general, the attractive interactions between oppositely
+charged species are strong and as such, the simple mixing of solutions
+containing dispersed constituents yield to a precipitation, or to a phase
+separation. We have developed means to control the electrostatically-driven
+attractions and to preserve the stability of the mixed solution. With these
+approaches, we designed novel core-shell nanostructures, e.g. as those obtained
+with polymers and iron oxide superparamagnetic nanoparticles. In this
+presentation, we show that electrostatic complexation can be used to tailor new
+functionalized nanoparticles and we provide examples related to biomedical
+applications in the domain of contrast agents for Magnetic Resonance Imaging.",0701663v1
+2007-02-07,Anomalous magnetic phase in an undistorted pyrochlore oxide Cd2Os2O7 induced by geometrical frustration,"We report on the muon spin rotation/relaxation study of a pyrochlore oxide,
+Cd2Os2O7, which exhibits a metal-insulator (MI) transition at T_{MI}~225 K
+without structural phase transition. It reveals strong spin fluctuation
+(>10^8/s) below the MI transition, suggesting a predominant role of geometrical
+spin frustration amongst Os^{5+} ions. Meanwhile, upon further cooling, a
+static spin density wave discontinuously develops below T_{SDW}~150 K. These
+observations strongly suggest the occurrence of an anomalous magnetic
+transition and associated change in the local spin dynamics in undistorted
+pyrochlore antiferromagnet.",0702164v2
+2007-11-28,"Chemical Tuning of Positive and Negative Magnetoresistances, and Superconductivity in 1222-type Ruthenocuprates","High critical-temperature superconductivity and large (colossal)
+magnetoresistances are two important electronic conducting phenomena found in
+transition metal oxides. High-Tc materials have applications such as
+superconducting magnets for MRI and NMR, and magnetoresistive materials may
+find use in magnetic sensors and spintronic devices. Here we report chemical
+doping studies of RuSr2(R2-xCex)Cu2O10-d ruthenocuprates which show that a
+single oxide system can be tuned between superconductivity at high hole dopings
+and varied magnetoresistive properties at low doping levels. A robust variation
+of negative magnetoresistance with hole concentration is found in the
+RuSr2R1.8-xY0.2CexCu2O10-d series, while RuSr2R1.1Ce0.9Cu2O10-d materials show
+an unprecedented crossover from negative to positive magnetoresistance with
+rare earth (R) ion radius.",0711.4611v1
+2008-08-16,All Oxide Ferromagnet/Semiconductor Epitaxial Heterostructures,"Oxide based ferromagnet/semiconductor heterostructures offer substantial
+advantages for spin electronics. We have grown (111) oriented Fe3O4 thin films
+and Fe3O4/ZnO heterostructures on ZnO(0001) and Al2O3(0001) substrates by
+pulsed laser deposition. High quality crystalline films with mosaic spread as
+small as 0.03 degree, sharp interfaces, and rms surface roughness of 0.3 nm
+were achieved. Magnetization measurements show clear ferromagnetic behavior of
+the magnetite layers with a saturation magnetization of 3.2 muB/f.u. at 300 K.
+Our results demonstrate that the Fe3O4/ZnO system is an intriguing and
+promising candidate for the realization of multi-functional heterostructures.",0808.2245v1
+2008-12-30,Structure and magnetism in ultrathin iron oxides characterized by low energy electron microscopy,"We have grown epitaxial films a few atomic layers thick of iron oxides on
+ruthenium. We characterize the growth by low energy electron microscopy. Using
+selected area diffraction and intensity vs. voltage spectroscopy, we detect two
+distinct phases which are assigned to wustite and magnetite. Spin polarized low
+energy electron microscopy shows magnetic domain patterns in the magnetite
+phase at room temperature.",0812.5049v2
+2009-08-05,Non-DMS related ferromagnetism in transition metal doped zinc oxide,"We review pitfalls in recent efforts to make a conventional semiconductor,
+namely ZnO, ferromagnetic by means of doping with transition metal ions. Since
+the solubility of those elements is rather low, formation of secondary phases
+and the creation of defects upon low temperature processing can lead to
+unwanted magnetic effects. Among others, ion implantation is a method of
+doping, which is highly suited for the investigation of those effects. By
+focussing mainly on Fe, Co or Ni implanted ZnO single crystals we show that
+there are manifold sources for ferromagnetism in this material which can easily
+be confused with the formation of a ferromagnetic diluted magnetic
+semiconductor (DMS). We will focus on metallic as well as oxide precipitates
+and the difficulties of their identification.",0908.0645v1
+2010-02-04,Realistic Modeling of Complex Oxide Materials,"Since electronic and magnetic properties of many transition-metal oxides can
+be efficiently controlled by external factors such as the temperature,
+pressure, electric or magnetic field, they are regarded as promising materials
+for various applications. From the viewpoint of electronic structure, these
+phenomena are frequently related to the behavior of a small group of states
+close to the Fermi level. The basic idea of this project is to construct a
+low-energy model for the states near the Fermi level on the basis of
+first-principles density functional theory, and to study this model by modern
+many-body techniques. After a brief review of the method, the abilities of this
+approach will be illustrated on a number of examples, including multiferroic
+manganites and spin-orbital-lattice coupled phenomena in RVO3 (R being the
+three-valent element).",1002.0905v1
+2010-09-17,"Role of oxygen-oxygen hopping in the three-band copper-oxide model: quasiparticle weight, metal insulator and magnetic phase boundaries, gap values and optical conductivity","We investigate the effect of oxygen-oxygen hopping on the three-band
+copper-oxide model relevant to high-$T_c$ cuprates, finding that the physics is
+changed only slightly as the oxygen-oxygen hopping is varied. The location of
+the metal-insulator phase boundary in the plane of interaction strength and
+charge transfer energy shifts by $\sim 0.5$eV or less along the charge transfer
+axis, the quasiparticle weight has approximately the same magnitude and doping
+dependence and the qualitative characteristics of the electron-doped and
+hole-doped sides of the phase diagram do not change. The results confirm the
+identification of La$_2$CuO$_4$ as a material with intermediate correlation
+strength. However, the magnetic phase boundary as well as higher-energy
+features of the optical spectrum are found to depend on the magnitude of the
+oxygen-oxygen hopping. We compare our results to previously published one-band
+and three-band model calculations.",1009.3490v2
+2010-10-30,Metal-Insulator Transition and Magnetic Order in the Pyrochlore Oxide Hg2Ru2O7,"We report results of NMR experiments on the ruthenium oxide Hg2Ru2O7 with the
+pyrochlore structure, which exhibits a metal-insulator transition at TMI = 107
+K. In the metallic phase above TMI, the nuclear spin-lattice relaxation rate
+1/T1 and the Knight shift at the Hg sites follow the Korringa relation,
+indicating the absence of substantial spatial spin correlation. At low
+temperatures in the insulating phase, 99,101Ru-NMR signals are observed at zero
+magnetic field, providing evidence for a commensurate antiferromagnetic order.
+The estimated ordered moment is about 1 muB per Ru, much smaller than 3 muB
+expected for the ionic (4d)3plus configuration of Ru5plus. Thus the localized
+spin models are not appropriate for the insulating phase of Hg2Ru2O7. We also
+discuss possible antiferromagnetic spin structures.",1011.0049v2
+2010-12-11,Magnetism in C or N-doped MgO and ZnO: density-functional study of impurity pairs,"It is shown that substitution of C or N for O recently proposed as a way to
+create ferromagnetism in otherwise nonmagnetic oxide insulators is curtailed by
+formation of impurity pairs, and the resultant C2 spin=1 dimers as well as the
+isoelectronic N2^{2+} interact antiferromagneticallly in p-type MgO. For
+C-doped ZnO, however, we demonstrate using the HSE hybrid functional that a
+resonance of the spin-polarized C2 pp\pi* states with the host conduction band
+results in a long-range ferromagnetic interaction. Magnetism of open-shell
+impurity molecules is proposed as a possible route to d0-ferromagnetism in
+oxide spintronic materials.",1012.2439v1
+2011-04-11,The High Temperature Superconductivity in Cuprates,"We discuss the high-temperature superconductivity in copper oxide ceramics.
+We propose an effective Hamiltonian to describe the dynamics of electrons or
+holes injected into the copper oxide layers. We show that our approach is able
+to account for both the pseudogap and the superconductivity gap. For the
+hole-doped cuprates we discuss in details the underdoped, optimal doped, and
+overdoped regions of the phase diagram. In the underdoped region we determine
+the doping dependence of the upper critical magnetic field, the vortex region,
+and the discrete states bounded to the core of isolated vortices. We explain
+the origin of the Fermi arcs and Fermi pockets. Moreover, we discuss the
+recently reported peculiar dependence of the specific heat on the applied
+magnetic field. We determine the critical doping where the pseudogap vanishes.
+We find that in the overdoped region the superconducting transition is
+described by the conventional d-wave BCS theory. We discuss the optimal doping
+region and the crossover between the underdoped region and the overdoped
+region. We also discuss briefly the electron-doped cuprate superconductors.",1104.1857v3
+2011-05-13,Room temperature p-induced surface ferromagnetism,"We prove a spontaneous magnetization of the oxygen-terminated ZnO (0001)
+surface by utilizing a multi-code, SIESTA and KKR, first-principles approach,
+involving both LSDA+U and selfinteraction corrections (SIC) to treat electron
+correlation effects. Critical temperatures are estimated from Monte Carlo
+simulations, showing that at and above 300 K the surface is thermodynamically
+stable and ferromagnetic. The observed half-metallicity and long-range magnetic
+order originate from the presence of p-holes in the valence band of the oxide.
+The mechanism is universal in ionic oxides and points to a new route for the
+design of ferromagnetic low dimensional systems.",1105.2777v1
+2011-06-29,A variational pseudo-self-interaction correction approach: ab-initio description of correlated oxides and molecules,"We present a fully variational generalization of the pseudo self-interaction
+correction (VPSIC) approach previously presented in two implementations based
+on plane-waves and atomic orbital basis set, known as PSIC and ASIC,
+respectively. The new method is essentially equivalent to the previous version
+for what concern the electronic properties, but it can be exploited to
+calculate total-energy derived properties as well, such as forces and
+structural optimization. We apply the method to a variety of test cases
+including both non-magnetic and magnetic correlated oxides and molecules,
+showing a generally good accuracy in the description of both structural and
+electronic properties.",1106.5993v1
+2013-03-05,Suppression of Magnetic Phase Separation in Epitaxial SrCoOx Films,"Using pulsed laser deposition and a unique fast quenching method, we have
+prepared SrCoOx epitaxial films on SiTiO3 substrates. As electrochemical
+oxidation increases the oxygen content from x = 2.75 to 3.0, the films tend to
+favor the discrete magnetic phases seen in bulk samples for the homologous
+series SrCoO(3-n/8) (n = 0, 1, 2). Unlike bulk samples, 200nm thick films
+remain single phase throughout the oxidation cycle. 300 nm films can show two
+simultaneous phases during deoxidation. These results are attributed to finite
+thickness effects and imply the formation of ordered regions larger than
+approximately 300 nm.",1303.1149v1
+2013-04-08,Spin states of iron impurities in magnesium oxide under pressure: A possible intermediate state,"Ferropericlase (Mg,Fe)O is a major lower mantle mineral, and studying its
+properties is a fundamental step toward understanding the Earth's interior.
+Here, we performed a first-principles investigation on the properties of iron
+as an isolated impurity in magnesium oxide, which is the condition of
+ferropericlase under which iron-iron interactions could be neglected. The
+calculations were carried using the all-electron full-potential linearized
+augmented plane wave method within the density functional theory in the
+generalized gradient approximation plus the on-site Hubbard correction. We
+present the electronic and magnetic properties, electric and magnetic hyperfine
+splitting of this impurity in high and low spin states for several charge
+states at zero pressure, which were then extended to high pressures. For the
+impurity in the neutral charge state, our results indicated that there is a
+metastable intermediate spin state (S=1), in addition to the high (S=2) and low
+(S=0) spin states. Those results were discussed in the context of an
+intermediate spin state, experimentally identified in ferrosilicate perovskite.",1304.2227v1
+2013-07-20,Phase diagrams of voltage-gated oxide interfaces with strong Rashba coupling,"We propose a model for the two-dimensional electron gas formed at the
+interface of oxide heterostructures that includes a Rashba spin-orbit coupling
+proportional to an electric field oriented perpendicularly to the interface.
+Taking into account the electron density dependence of this electric field
+confining the electron gas at the interface, we report the occurrence of a
+phase separation instability (signaled by a negative compressibility) for
+realistic values of the spin-orbit coupling and of the electronic
+band-structure parameters at zero temperature. We extend the analysis to finite
+temperatures and in the presence of an in-plane magnetic field, thereby
+obtaining two phase diagrams which exhibit a phase separation dome. By varying
+the gating potential the phase separation dome may shrink and vanish at zero
+temperature into a quantum critical point where the charge fluctuates
+dynamically. Similarly the phase separation may be spoiled by a planar magnetic
+field even at zero temperature leading to a line of quantum critical points.",1307.5427v3
+2014-02-15,Quantifying and controlling the magnetic dipole contribution to 1.5 $μ$m light emission in erbium-doped yttrium oxide,"We experimentally quantify the contribution of magnetic dipole (MD)
+transitions to the near-infrared light emission from trivalent erbium-doped
+yttrium oxide (Er$^{3+}$:Y$_2$O$_3$). Using energy-momentum spectroscopy, we
+demonstrate that the $^4$I$_{13/2}{\to}^4$I$_{15/2}$ emission near 1.5 $\mu$m
+originates from nearly equal contributions of electric dipole (ED) and MD
+transitions that exhibit distinct emission spectra. We then show how these
+distinct spectra, together with the differing local density of optical states
+(LDOS) for ED and MD transitions, can be leveraged to control Er$^{3+}$
+emission in structured environments. We demonstrate that far-field emission
+spectra can be tuned to resemble almost pure emission from either ED or MD
+transitions, and show that the observed spectral modifications can be
+accurately predicted from the measured ED and MD intrinsic emission rates.",1402.3717v1
+2014-08-07,Magneto-transport properties of oriented Mn2CoAl films sputtered on thermally oxidized Si substrates,"Spin gapless semiconductors are interesting novel class of materials by
+embracing both magnetism and semiconducting. Its potential application in
+future spintronics requires realization in thin film form. In this letter, we
+report a successful growth of spin gapless Mn2CoAl films on thermally oxidized
+Si substrates by magnetron sputtering deposition. The films deposited at 673K
+are well oriented to (001) direction and display a uniform-crystalline surface.
+Magnetotransport measurements on the oriented films reveal a
+semiconducting-like resistivity, small anomalous Hall conductivity and linear
+magnetoresistance (MR) representative of the transport signatures of spin
+gapless semiconductors. The magnetic properties of the films have also been
+investigated and compared to that of bulk Mn2CoAl, with small discrepancy
+induced by the composition deviation.",1408.1547v1
+2015-01-09,Giant spin-phonon-electronic coupling in a 5d oxide,"Enhanced coupling of material properties offers new fundamental insights and
+routes to multifunctional devices. In this context 5d oxides provide new
+paradigms of cooperative interactions driving novel emergent behavior. This is
+exemplified in 5d osmates that host a metal-insulator transition (MIT) driven
+by magnetic order. Here we consider the most robust case, the 5d perovskite
+NaOsO3, and reveal a giant coupling between spin and phonon through a frequency
+shift of {\Delta}{\omega}=40 cm-1, the largest measured in any material. We
+identify the dominant octahedral breathing mode and show isosymmetry with spin
+ordering which induces dynamic charge disproportionation that sheds new light
+on the MIT. The occurrence of the dramatic spin-phonon-electronic coupling in
+NaOsO3 is due to a property common to all 5d materials: the large spatial
+extent of the 5d ion. This allows magnetism to couple to phonons on an
+unprecedented scale and consequently offers multiple new routes to enhanced
+coupled phenomena.",1501.02290v1
+2015-06-23,Interface exchange processes in LaAlO$_3$/SrTiO$_3$ induced by oxygen vacancies,"Understanding the role of defects in oxide heterostructures is crucial for
+future materials control and functionalization. We hence study the impact of
+oxygen vacancies (OVs) at variable concentrations on orbital- and spin exchange
+in the LaAlO$_3$/SrTiO$_3$ interface by first principles many-body theory and
+real-space model-Hamiltonian techniques. Intricate interplay between Hubbard
+$U$ and Hund's coupling $J_{\rm H}$ for OV-induced correlated states is
+demonstrated. Orbital polarization towards an effective $e_g$ state with
+predominant local antiferromagnetic alignment on Ti sites near OVs is
+contrasted with $t_{2g}(xy)$ states with ferromagnetic tendencies in the
+defect-free regions. Different magnetic phases are identified, giving rise to
+distinct net-moment behavior at low and high OV concentrations. This provides a
+theoretical basis for prospective tailored magnetism by defect manipulation in
+oxide interfaces.",1506.07066v3
+2016-01-15,Analysis of electronic and structural properties of surfaces and interfaces based on LaAlO3 and SrTiO3,"Recently, it was established that a two-dimensional electron system can arise
+at the interface between two oxide insulators LaAlO3 and SrTiO3. This
+paradigmatic example exhibits metallic behaviour and magnetic properties
+between non-magnetic and insulating oxides. Despite a huge amount of
+theoretical and experimental work a thorough understanding has yet to be
+achieved. We analyzed the structural deformations of a LaAlO3 (001) slab
+induced by hydrogen ad-atoms and oxygen vacancies at its surface by means of
+density functional theory. Moreover, we investigated the influence of surface
+reconstruction on the density of states and determined the change of the local
+density of states at the Fermi level with increasing distance from the surface
+for bare LaAlO3 and for a conducting LaAlO3/SrTiO3 interface. In addition, the
+Al-atom displacements and distortions of the TiO6-octahedra were estimated.",1601.04009v1
+2016-07-24,Super-giant magnetoresistance at room-temperature in copper nanowires due to magnetic field modulation of potential barrier heights at nanowire-contact interfaces,"We have observed a super-giant (~10,000,000%) negative magnetoresistance at
+39 mT field in Cu nanowires contacted with Au contact pads. In these nanowires,
+potential barriers form at the two Cu/Au interfaces because of Cu oxidation
+that results in an ultrathin copper oxide layer forming between Cu and Au.
+Current flows when electrons tunnel through, and/or thermionically emit over,
+these barriers. A magnetic field applied transverse to the direction of current
+flow along the wire deflects electrons toward one edge of the wire because of
+the Lorentz force, causing electron accumulation at that edge and depletion at
+the other. This lowers the potential barrier at the accumulated edge and raises
+it at the depleted edge, causing a super-giant magnetoresistance at room
+temperature.",1607.07091v1
+2016-09-16,Interface Engineering in La0.67Sr0.33MnO3-SrTiO3 Heterostructures,"Interface engineering is an extremely useful tool for systematically
+investigating materials and the various ways materials interact with each
+other. We describe different interface engineering strategies designed to
+reveal the origin of the electric and magnetic dead-layer at La0.67Sr0.33MnO3
+interfaces. La0.67Sr0.33MnO3 is a key example of a strongly correlated
+peroskite oxide material in which a subtle balance of competing interactions
+gives rise to a ferromagnetic metallic groundstate. This balance, however, is
+easily disrupted at interfaces. We systematically vary the dopant profile, the
+disorder and the oxygen octahedra rotations at the interface to investigate
+which mechanism is responsible for the dead layer. We find that the magnetic
+dead layer can be completely eliminated by compositional interface engineering
+such that the polar discontinuity at the interface is removed. This, however,
+leaves the electrical dead-layer largely intact. We find that deformations in
+the oxygen octahedra network at the interface are the dominant cause for the
+electrical dead layer.",1609.04976v1
+2018-02-05,Intrinsic spin-orbit torque arising from Berry curvature in metallic-magnet/Cu-oxide interface,"We report the observation of the intrinsic damping-like spin-orbit torque
+(SOT) arising from the Berry curvature in metallic-magnet/CuO$_x$
+heterostructures. We show that a robust damping-like SOT, an order of magnitude
+larger than a field-like SOT, is generated in the heterostructure despite the
+absence of the bulk spin-orbit effect in the CuO$_x$ layer. Furthermore, by
+tuning the interface oxidation level, we demonstrate that the field-like SOT
+changes drastically and even switches its sign, which originates from oxygen
+modulated spin-dependent disorder. These results provide an important
+information for fundamental understanding of the physics of the SOTs.",1802.01285v2
+2018-11-13,Nanoscale ordered Layered-Segregation of Cobalt and Iron in the Perovskite SmFe0.5Co0.5O3,"The possibility to segregate cobalt and iron in a single perovskite, at a
+nanoscale in the form of layers has been investigated, using sol gel technic
+synthesis. Quite remarkably, it is shown that such a nanoscale ordering, which
+can only be detected by a combined HAADF-STEM and EELS study, has a significant
+impact upon the magnetic properties of this SmFe0.5Co0.5O3 oxide. This suggests
+that careful nanoscale characterization of oxides will be necessary in the
+future before proceeding to a viable interpretation of their physical
+properties, at least in the field of magnetism.",1811.05221v1
+2019-05-23,Topological Hall Effect and Emergent Skyrmion Crystal in Manganite-Iridate Oxide Interfaces,"Scalar spin chirality is expected to induce a finite contribution to the Hall
+response at low temperatures. We study this spin-chirality-driven Hall effect,
+known as the topological Hall effect, at the manganite side of the interface
+between La$_{1-x}$Sr$_{x}$MnO$_{3}$ and SrIrO$_3$. The ferromagnetic
+double-exchange hopping at the manganite layer, in conjunction with the
+Dzyaloshinskii-Moriya (DM) interaction which arises at the interface due to
+broken inversion symmetry and strong spin-orbit coupling from the iridate
+layer, could produce a skyrmion-crystal (SkX) phase in the presence of an
+external magnetic field. Using the Monte Carlo technique and a two-orbital
+spin-fermion model for manganites, supplemented by an in-plane DM interaction,
+we obtain phase diagrams which reveal at low temperatures a clear SkX phase and
+also a low-field spin-spiral phase. Increasing temperature, a skyrmion-gas
+phase, precursor of the SkX phase upon cooling, was identified. The topological
+Hall effect primarily appears in the SkX phase, as observed before in oxide
+heterostructures. We conclude that the manganite-iridate superlattices provide
+another useful platform to explore a plethora of unconventional magnetic and
+transport properties.",1905.09887v2
+2013-08-02,Termination control of electronic phases in oxide thin films and interfaces: LaAlO3/SrTiO3(001),"A wealth of intriguing properties emerge in the seemingly simple system
+composed of the band insulators LaAlO3 and SrTiO3 such as a two-dimensional
+electron gas, superconductivity and magnetism. In this paper we review the
+current insight obtained from first principles calculations on the mechanisms
+governing the behavior of thin LaAlO3 films on SrTiO3(001). In particular, we
+explore the strong dependence of the electronic properties on the surface and
+interface termination, the finite film thickness, lattice polarization and
+defects. A further aspect that is addressed is how the electronic behavior and
+functionality can be tuned by a SrTiO3 capping layer, adsorbates and metallic
+contacts. Lastly, we discuss recent reports on the coexistence of magnetism and
+superconductivity in this system for what they might imply about the electronic
+structure of this system.",1308.0481v1
+2016-11-11,MgGa2O4 spinel barrier for magnetic tunnel junctions: coherent tunneling and low barrier height,"Epitaxial Fe/magnesium gallium spinel oxide (MgGa2O4)/Fe(001) magnetic tunnel
+junctions (MTJs) were fabricated by magnetron sputtering. Tunnel
+magnetoresistance (TMR) ratio up to 121% at room temperature (196% at 4 K) was
+observed, suggesting a TMR enhancement by the coherent tunneling effect in the
+MgGa2O4 barrier. The MgGa2O4 layer had a spinel structure and it showed good
+lattice matching with the Fe layers owing to slight tetragonal lattice
+distortion of MgGa2O4. Barrier thickness dependence of the tunneling resistance
+and current-voltage characteristics revealed that the barrier height of the
+MgGa2O4 barrier is much lower than that in an MgAl2O4 barrier. This study
+demonstrates the potential of Ga-based spinel oxides for MTJ barriers having a
+large TMR ratio at a low resistance area product.",1611.03606v1
+2009-12-17,Surface magnetism in ZnO/Co3O4 mixtures,"We recently reported the observation of room temperature ferromagnetism in
+mixtures of ZnO and Co3O4 despite the diamagnetic and antiferromagnetic
+character of these oxides respectively. Here we present a detailed study on the
+electronic structure of this material in order to account for this unexpected
+ferromagnetism. Electrostatic interactions between both oxides lead to a
+dispersion of Co3O4 particles over the surface of ZnO larger ones. As a
+consequence, the reduction of Co+3 to Co2+ at the particle surface takes place
+as evidenced by XAS measurements and optical spectrocopy. This reduction allows
+to xplain the observed ferromagnetic signal within the well established
+theories of magnetism.",0912.3458v1
+2013-09-01,High-pressure cupric oxide: a room-temperature multiferroic,"Multiferroic materials, in which ferroelectric and magnetic ordering coexist,
+are of fundamental interest for the development of multi-state memory devices
+that allow for electrical writing and non-destructive magnetic read-out
+operation. The great challenge is to create multiferroic materials that operate
+at room-temperature and have a large ferroelectric polarization P. Cupric
+oxide, CuO, is promising because of its large P ~ 10^{2} {\mu}C.m^{-2}, but is
+unfortunately only multiferroic in a temperature range of 20 K, from 210 to 230
+K. Here, using a combination of density functional theory and Monte Carlo
+calculations, we establish that pressure-driven phase competition induces a
+giant stabilization of the multiferroic phase of CuO, which at 20-40 GPa
+becomes stable in a domain larger than 300 K, from 0 to T > 300 K. Thus, under
+high-pressure, CuO is predicted to be a room-temperature multiferroic with
+large polarization.",1309.0246v1
+2014-05-06,Magnetic and transport signatures of Rashba spin-orbit coupling on the ferromagnetic Kondo lattice model in two dimensions,"Motivated by emergent phenomena at oxide surfaces and interfaces,
+particularly those involving transition metal oxides with perovskite crystal
+structure such as LaTiO3/SrTiO3, we examine the ferromagnetic Kondo lattice
+model (FKLM) in the presence of a Rashba spin-orbit coupling (RSOC). Using
+numerical techniques, under the assumption that the electrons on localized
+orbitals may be treated as classical continuum spins, we compute various
+charge, spin and transport properties on square clusters at zero temperature.
+We find that the main effect of the RSOC is the destruction of the
+ferromagnetic state present in the FKLM at low electron fillings, with the
+consequent suppression of conductivity. In addition, near half-filling the RSOC
+leads to a departure of the antiferromagnetic state of the FKLM with a
+consequent reduction to the intrinsic tendency to electronic phase separation.
+The interplay between phase separation on one side, and magnetic and transport
+properties on the other, is carefully analyzed as a function of the
+RSOC/hopping ratio.",1405.1240v2
+2014-05-13,From Spin Glass to Quantum Spin Liquid Ground States in Molybdate Pyrochlores,"We present new magnetic heat capacity and neutron scattering results for two
+magnetically frustrated molybdate pyrochlores: $S=1$ oxide Lu$_2$Mo$_2$O$_7$
+and $S={\frac{1}{2}}$ oxynitride Lu$_2$Mo$_2$O$_5$N$_2$. Lu$_2$Mo$_2$O$_7$
+undergoes a transition to an unconventional spin glass ground state at $T_f
+{\sim} 16$ K. However, the preparation of the corresponding oxynitride tunes
+the nature of the ground state from spin glass to quantum spin liquid. The
+comparison of the static and dynamic spin correlations within the oxide and
+oxynitride phases presented here reveals the crucial role played by quantum
+fluctuations in the selection of a ground state. Furthermore, we estimate an
+upper limit for a gap in the spin excitation spectrum of the quantum spin
+liquid state of the oxynitride of ${\Delta} {\sim} 0.05$ meV or
+${\frac{\Delta}{|\theta|}}\sim0.004$, in units of its antiferromagnetic Weiss
+constant ${\theta} {\sim}-121$ K.",1405.3172v1
+2014-05-24,Triclinic Ni0.6Co0.4TiO3 Ilmenite Oxide,"Forming a solid-solution of NiTiO3 and CoTiO3, two isostructural (ilmenite)
+and isosymmetrical (space group R-3) compounds, result in a single-phase
+compound with a remarkably low crystal symmetry. By neutron and X-ray
+synchrotron powder diffraction techniques, the space group symmetry of the
+Ni0.6Co0.4TiO3 sample was found to be triclinic P-1 at room temperature, far
+above the magnetic transition temperature. Ni and Co ions were found to prefer
+positions close to the octahedron center, whereas Ti ions took off-center
+positions. This structural distortion is the first known case in ilmenites and
+opens up ways to modify functional properties of magnetic oxides. Origin of the
+symmetry lowering is discussed.",1405.6330v1
+2016-08-18,Exotic Spin-Orbital Physics in Hybrid Oxides,"We compare the effective spin-orbital super\-exchange triggered by magnetic
+$3d$ impurities with $d^3$ and $d^2$ configurations and either no orbital
+degree of freedom (orbital dilution) or hole replacing a doublon (charge
+dilution) in a $4d^4$ Mott insulator with $S=1$ spins. Impurities causing
+orbital dilution act either as spin defects decoupled from the surrounding
+ions, or generate orbital polarons along $d^3$-$d^4$ hybrid bonds. The exchange
+on these bonds determines which orbital is occupied by a doublon on the host
+site. In case of charge dilution by $3d^2$ impurities additional $\propto
+T_i^+T_j^+$ terms arise which enhance orbital fluctuations. We show that such
+terms may radically change orbital pattern at relatively low doping by $x=1/8$
+hole defects. Our findings provide new perspective for future theoretical and
+experimental studies of doped transition metal oxides.",1608.05330v1
+2016-12-13,Multiple structural transitions driven by spin-phonon couplings in a perovskite oxide,"Spin-phonon interactions are central to many interesting phenomena, ranging
+from superconductivity to magnetoelectric effects. Yet, they are believed to
+have a negligible influence on the structural behavior of most materials. For
+example, magnetic perovskite oxides often undergo structural transitions
+accompanied by magnetic signatures whose minuteness suggests that the
+underlying spin-phonon couplings are largely irrelevant. Here we present an
+exception to this rule, showing that novel effects can occur as a consequence.
+Our first-principles calculations reveal that spin-phonon interactions are
+essential to reproduce the experimental observations on the phase diagram of
+magnetoelectric multiferroic BiCoO$_{3}$. Moreover, we predict that, under
+compression, these couplings lead to an unprecedented temperature-driven
+double-reentrant sequence of ferroelectric transitions. We propose how to
+modify BiCoO$_{3}$ via chemical doping to reproduce such striking effects at
+ambient conditions, thereby yielding useful multifunctionality.",1612.04356v1
+2018-01-19,Electric-field control of anomalous and topological Hall effects in oxide bilayer thin films,"One of the key technologies in spintronics is to tame spin-orbit coupling
+(SOC) that links spin and motion of electrons, giving rise to intriguing
+magneto-transport properties in itinerant magnets. Prominent examples of such
+SOC-based phenomena are anomalous and topological Hall effects. However,
+controlling them by electric field has remained unachieved since electric field
+tends to be screened in itinerant magnets. Here we demonstrate that both
+anomalous and topological Hall effects can be modulated by electric field in
+oxide heterostructures consisting of ferromagnetic SrRuO$_{3}$ and nonmagnetic
+SrIrO$_{3}$. We observed clear electric-field effect only when SrIrO$_{3}$ is
+inserted between SrRuO$_{3}$ and a gate dielectric. Our results establish that
+strong SOC of nonmagnetic materials such as SrIrO$_{3}$ is essential in
+electrical tuning of these Hall effects and possibly other SOC-related
+phenomena.",1801.06272v1
+2019-09-13,Tunable perpendicular exchange bias in oxide heterostructures,"The exchange bias effect is an essential component of magnetic memory and
+spintronic devices. Whereas recent research has shown that anisotropies
+perpendicular to the device plane provide superior stability against thermal
+noise, it has proven remarkably difficult to realize perpendicular exchange
+bias in thin-film structures. Here we demonstrate a strong perpendicular
+exchange bias effect in heterostructures of the quasi-two-dimensional canted
+antiferromagnet La$_2$CuO$_4$ and ferromagnetic (La,Sr)MnO$_3$ synthesized by
+ozone-assisted molecular beam epitaxy. The magnitude of this effect can be
+controlled via the doping level of the cuprate layers. Canted
+antiferromagnetism of layered oxides is thus a new and potentially powerful
+source of uniaxial anisotropy in magnetic devices.",1909.06152v1
+2019-09-19,Influence of magnetic ordering on the spectral properties of binary transition metal oxides,"Using the ab initio embedded DMFT (eDMFT) approach, we study the effect of
+long-range magnetic ordering on the spectral properties in the binary
+transition metal oxides, and find that the most significant changes appear in
+the momentum resolved spectral functions, which sharpen into quite well-defined
+bands in the antiferromagnetic (AFM) phase. The strongest change across the
+transition is found at the topmost valence band edge (VBE), which is commonly
+associated with the Zhang-Rice bound state. This VBE state strengthens in the
+AFM phase, but only for the minority spin component, which is subject to
+stronger fluctuations. A similar hybridized VBE state also appears in the DFT
+single-particle description of the AFM phase, but gets much stronger and
+acquires a well-defined energy in the eDMFT description.",1909.09189v1
+2020-12-02,Ballistic transport through quantum point contacts of multi-orbital oxides,"Linear and non-linear transport properties through an atomic-size point
+contact based on oxides two-dimensional electron gas is examined using the
+tight-binding method and the $\mathbf{k\cdot p}$ approach. The ballistic
+transport is analyzed in contacts realized at the (001) interface between band
+insulators $LaAlO_3$ and $SrTiO_3$ by using the Landauer-B\""uttiker method for
+many sub-bands derived from three Ti 3d orbitals ($d_{yz}$, $d_{zx}$ and
+$d_{xy}$) in the presence of an out-of-plane magnetic field. We focus
+especially on the role played by the atomic spin-orbit coupling and the
+inversion symmetry breaking term pointing out three transport regimes: the
+first, at low energies, involving the first $d_{xy}$-like sub-bands, where the
+conductance quantization is robust; a second one, at intermediate energies,
+entailing further $d_{xy}$-like sub-bands, where the sub-band splitting induced
+by the magnetic field is quenched; the third one, where the mixing between
+light $d_{xy}$-like, heavy $d_{yz}$-like and $d_{zx}$-like sub-bands is so
+strong that the conductance plateaus turn out to be very narrow. Very good
+agreement is found with recent experiments exploring the transport properties
+at low energies.",2012.01395v1
+2017-05-31,Tuning of Magnetic and Electrical Properties in Complex oxide Thin Films Deposited By Pulsed Laser Deposition,"Lanthanum manganite, LaMnO (LMO) is the parent compound for a class of hole
+doped(e.g. La1-xCaxMnO3, La1-xSrxMnO3) and electron doped (e.g. . La1-xCexMnO3,
+La1-xSnxMnO3) perovskite complex oxide materials. Strong correlation between
+the spin,lattice, charge and orbital degrees of freedom is a hallmark of these
+class of materials (popularly known as manganites). Competition and interplay
+of these degrees of freedom lead to a wide range of interesting electronic
+behavior including half-metallicity, colossal magneto-resistivity, etc.
+Although a lot of experimental research has been carried out on the hole doped
+and the electron doped counterparts, the parent system LMO remains less
+investigated. This could be attributed to the difficulty in making
+stoichiometric LMO (whether in bulk polycrystalline, single crystals or thin
+films). There exists phenomenon like double-exchange (DE) and
+anti-ferromagnetic super-exchange (SE) interactions which leads to
+ferromagnetism in LMO thin films. This project work is aimed at the fabrication
+and characterization of thin films of stoichiometric LMO and their structural,
+magnetic and electrical studies.",1705.11003v1
+2018-03-19,Clear variation of spin splitting by changing electron distribution at non-magnetic metal/Bi2O3 interfaces,"Large spin splitting at Rashba interface, giving rise to strong spin-momentum
+locking, is essential for efficient spin-to-charge conversion. Recently, a
+Cu/Bismuth oxide (Bi2O3) interface has been found to exhibit an efficient
+spin-to-charge conversion similar to a Ag/Bi interface with large Rashba spin
+splitting. However, the guiding principle of designing the metal/oxide
+interface for the efficient conversion has not been clarified yet. Here we
+report strong non-magnetic (NM) material dependence of spin splitting at
+NM/Bi2O3 interfaces. We employed spin pumping technique to inject spin current
+into the interface and evaluated the magnitude of interfacial spin-to-charge
+conversion. We observed large modulation and sign change in conversion
+coefficient which corresponds to the variation of spin splitting. Our
+experimental results together with first-principles calculations indicate that
+such large variation is caused by material dependent electron distribution near
+the interface. The results suggest that control of interfacial electron
+distribution by tuning the difference in work function across the interface may
+be an effective way to tune the magnitude and sign of spin-to-charge conversion
+and Rashba parameter at interface.",1803.06789v1
+2018-08-07,"Development of Ferromagnetic Fluctuations in Heavily Overdoped (Bi,Pb)_2_Sr_2_CuO_6+delta_ Copper Oxides","We demonstrate the presence of ferromagnetic (FM) fluctuations in the
+superconducting and non-superconducting heavily overdoped regimes of
+high-temperature superconducting copper oxides, using
+(Bi,Pb)_2_Sr_2_CuO_6+delta_ (Bi-2201) single crystals. Magnetization curves
+exhibit a tendency to be saturated in high magnetic fields at low temperatures
+in the heavily overdoped crystals, which is probably a precursor phenomenon of
+a FM transition at a lower temperature. Muon spin relaxation detects the
+enhancement of spin fluctuations at high temperatures below 200 K.
+Correspondingly, the ab-plane resistivity follows a 4/3 power law in a wide
+temperature range, which is characteristic of metals with two-dimensional FM
+fluctuations due to itinerant electrons. As the Wilson ratio evidences the
+enhancement of spin fluctuations with hole doping in the heavily overdoped
+regime, it is concluded that two-dimensional FM fluctuations reside in the
+heavily overdoped Bi-2201 cuprates, which is probably related to the decrease
+in the superconducting transition temperature in the heavily overdoped
+cuprates.",1808.02317v1
+2018-08-17,Electromagnon excitation in cupric oxide measured by Fabry-Pérot enhanced terahertz Mueller matrix ellipsometry,"Here we present the use of Fabry-P\'erot enhanced terahertz (THz) Mueller
+matrix ellipsometry to measure an electromagnon excitation in monoclinic cupric
+oxide (CuO). As a magnetically induced ferroelectric multiferroic, CuO exhibits
+coupling between electric and magnetic order. This gives rise to special
+quasiparticle excitations at THz frequencies called electromagnons. In order to
+measure the electromagnons in CuO, we exploit single-crystal CuO as a THz
+Fabry-P\'erot cavity to resonantly enhance the excitation's signature. This
+enhancement technique enables the complex index of refraction to be extracted.
+We observe a peak in the absorption coefficient near 0.705 THz and 215 K, which
+corresponds to the electromagnon excitation. This absorption peak is observed
+along only one major polarizability axis in the monoclinic a-c plane. We show
+the excitation can be represented using the Lorentz oscillator model, and
+discuss how these Lorentz parameters evolve with temperature. Our findings are
+in excellent agreement with previous characterizations by THz time-domain
+spectroscopy (THz-TDS), which demonstrates the validity of this enhancement
+technique.",1808.06005v1
+2019-02-19,Superexchange interactions between spin-orbit-coupled $j\!\approx\!1/2$ ions in oxides with face-sharing ligand octahedra,"Using ab initio wave-function-based calculations, we provide valuable
+insights with regard to the magnetic exchange in 5$d$ and 4$d$ oxides with
+face-sharing ligand octahedra, BaIrO$_3$ and BaRhO$_3$. Surprisingly strong
+antiferromagnetic Heisenberg interactions as large as 400 meV are computed for
+idealized iridate structures with 90$^{\circ}$ Ir-O-Ir bond angles and in the
+range of 125 meV for angles of 80$^{\circ}$ as measured experimentally in
+BaIrO$_3$. These estimates exceed the values derived so far for corner-sharing
+and edge-sharing systems and motivate more detailed experimental investigations
+of quantum magnets with extended 5$d$/4$d$ orbitals and networks of
+face-sharing ligand cages. The strong electron-lattice couplings evidenced by
+our calculations suggest rich phase diagrams as function of strain and
+pressure, a research direction with much potential for materials of this type.",1902.07269v2
+2019-04-07,Polarity and spin-orbit coupling induced large interfacial exchange coupling an asymmetric charge transfer in iridate-manganite heterostructure,"Charge transfer is of particular importance in manipulating the interface
+physics in transition-metal oxide heterostructures. In this work, we have
+fabricated epitaxial bilayers composed of polar 3d LaMnO3 and nonpolar 5d
+SrIrO3. Systematic magnetic measurements reveal an unexpectedly large exchange
+bias effect in the bilayer, together with a dramatic enhancement of the
+coercivity of LaMnO3. Based on first-principles calculations and x-ray
+absorption spectroscopy measurements, such a strong interfacial magnetic
+coupling is found closely associated with the polar nature of LaMnO3 and the
+strong spin-orbit interaction in SrIrO3, which collectively drives an
+asymmetric interfacial charge transfer and leads to the emergence of an
+interfacial spin glass state. Our study provides new insight into the charge
+transfer in transition-metal oxide heterostructures and offers a novel means to
+tune the interfacial exchange coupling for a variety of device applications.",1904.03613v2
+2019-12-17,Tuning Crystal Field Potential by Orbital Dilution in $d^4$ Oxides,"We investigate the interplay between Coulomb driven orbital order and
+octahedral distortions in strongly correlated Mott insulators due to orbital
+dilution, i.e., doping by metal ions without an orbital degree of freedom. In
+particular, we focus on layered transition metal oxides and study the effective
+spin-orbital exchange due to $d^3$ substitution at $d^4$ sites. The structure
+of the $d^3-d^4$ spin-orbital coupling between the impurity and the host in the
+presence of octahedral rotations favors a distinct type of orbital polarization
+pointing towards the impurity and outside the impurity--host plane. This yields
+an effective lattice potential that generally competes with that associated
+with flat octahedra and, in turn, can drive an inversion of the crystal field
+interaction.",1912.07975v1
+2020-06-26,Spin and orbital Edelstein effect in an oxide two-dimensional electron gas: theory and application to AlO$_x$/SrTiO$_{3}$,"The Edelstein effect provides the purely electrical generation and control of
+a homogeneous magnetization in primarily nonmagnetic materials with broken
+inversion symmetry. Usually, only the spin density response to an external
+electric field is discussed. Here, we report on the electrically induced
+magnetization containing spin as well as orbital contributions in the
+topological oxide two-dimensional electron gas at the interface between
+SrTiO$_3$ and AlO. We find that in this particular system the orbital Edelstein
+effect exceeds the spin Edelstein effect by more than one order of magnitude.
+The main reason are orbital moments of different magnitude in the
+Rashba-like-split band pairs.",2006.14958v1
+2020-08-12,Stabilization of a honeycomb lattice of IrO$_6$ octahedra in superlattices with ilmenite-type MnTiO$_3$,"In the quest for quantum spin liquids, thin films are expected to open the
+way for the control of intricate magnetic interactions in actual materials by
+exploiting epitaxial strain and two-dimensionality. However, materials
+compatible with conventional thin-film growth methods have largely remained
+undeveloped. As a promising candidate towards the materialization of quantum
+spin liquids in thin films, we here present a robust ilmenite-type oxide with a
+honeycomb lattice of edge-sharing IrO$_6$ octahedra artificially stabilized by
+superlattice formation with an ilmenite-type antiferromagnetic oxide MnTiO$_3$.
+The stabilized sub-unit-cell-thick Mn-Ir-O layer is isostructural to MnTiO$_3$,
+having the atomic arrangement corresponding to ilmenite-type MnTiO$_3$ not
+discovered yet. By spin Hall magnetoresistance measurements, we found that
+antiferromagnetic ordering in the ilmenite Mn sublattice is suppressed by
+modified magnetic interactions in the MnO$_6$ planes via the IrO$_6$ planes.
+These findings lay the foundation for the creation of two-dimensional Kitaev
+candidate materials, accelerating the discovery of exotic physics and
+applications specific to quantum spin liquids.",2008.05236v2
+2021-07-30,Emergence of Ferromagnetism Through the Metal-Insulator Transition in Undoped Indium Tin Oxide Films,"We present a detailed study of the emergence of bulk ferromagnetism in low
+carrier density samples of undoped indium tin oxide (ITO). We used annealing to
+increase the density of oxygen vacancies and change sample morphology without
+introducing impurities through the metal insulator transition (MIT). We
+utilized a novel and highly sensitive ""Corbino-disk torque magnetometry""
+technique to simultaneously measure the thermodynamic and transport effects of
+magnetism on the same sample after successive annealing. With increased sample
+granularity, carrier density increased, the sample became more metallic, and
+ferromagnetism appeared as resistance approached the MIT. Ferromagnetism was
+observed through the detection of magnetization hysteresis, anomalous Hall
+effect (AHE), and hysteretic magnetoresistance. A sign change of the AHE as the
+MIT is approached may elucidate the interplay between the impurity band and the
+conduction band in the weakly insulating side of the MIT.",2107.14463v1
+2021-08-17,Importance of the many-body effects for structural properties of the novel iron oxide: Fe$_2$O,"The importance of many-body effects on electronic and magnetic properties and
+stability of different structural phases was studied in novel iron oxide -
+Fe$_2$O. It was found that while Hubbard repulsion hardly affects the
+electronic spectrum of this material ($m^*/m \sim 1.2$), but it strongly
+changes its phase diagram shifting critical pressures of structural transitions
+to much lower values. Moreover, one of the previously obtained in the density
+functional theory (DFT) structures (P$\bar 3$m1) becomes energetically unstable
+if many-body effects are taken into consideration. It is shown that this is an
+account of magnetic moment fluctuations in the DFT+DMFT approach, which
+strongly contributes to modification of the phase diagram of Fe$_2$O.",2108.07645v1
+2021-12-21,Pyrochlore Oxide Hg2Os2O7 on Verge of Metal-Insulator Boundary,"Semimetallic osmium pyrochlore oxide Cd2Os2O7 undergoes a magnetic transition
+to an all-in-all-out (AIAO)-type order at 227 K, followed by a crossover to an
+AIAO insulator at around 210 K. Here, we studied the isostructural and
+isoelectronic compound Hg2Os2O7 through thermodynamic measurements, muSR
+spectroscopy and neutron diffraction experiments. A similar magnetic
+transition, probably to an AIAO-type order, was observed at 88 K, while the
+resistivity showed a decrease at the transition and remained metallic down to 2
+K. Thus, the ground state of Hg2Os2O7 is most likely an AIAO semimetal, which
+is analogous to the intermediate-temperature state of Cd2Os2O7. Hg2Os2O7 exists
+on the verge of the metal-insulator boundary on the metal side and provides an
+excellent platform for studying the electronic instability of 5d electrons with
+moderate electron correlations and strong spin-orbit interactions.",2112.11558v1
+2022-02-03,Synthesis of Core/Shell Ti/TiOx Photocatalyst via Single-Mode Magnetic Microwave Assisted Direct Oxidation of TiH2,"Submicron core/shell Ti/TiOx photocatalyst is successfully synthesized via
+single-mode magnetic microwave (SMMW) assisted direct oxidation of planetary
+ball-milled TiH2. The thickness of TiOx shell including highly concentrated
+defects such as Ti3+ and/or oxygen vacancies is controllable in the range from
+6 to over 18 nm by varying the treatment time in the SMMW assisted reaction. In
+addition to its quite narrow optical bandgap (1.34-2.69 eV) and efficient
+visible-light absorption capacity, the submicron Ti/TiOx particle exhibits
+superior photocatalytic performance towards H2 production from water under both
+UV and visible-light irradiation to compare with a commercial TiO2
+photocatalyst (P-25). Such excellent performance can be achieved by the
+synergetic effect of enhancement in visible light absorption capacity and
+photo-excited carrier separation because of the highly concentrated surface
+defects and the specific Ti/TiOx core/shell structure, respectively.",2202.01363v1
+2022-03-07,Understanding the growth of high-aspect-ratio grains in granular L10-FePt thin-film magnetic media,"A systematic investigation has been performed to optimize the microstructure
+of $\mathrm{L1_0-FePt-SiO_x}$ granular thin film as recording media for
+heat-assisted magnetic recording. The FePt-BN nucleation layer, which is stable
+even at $700^\circ \text{C}$, is used to control the grain sizes and
+microstructure during high-temperature processing. The study finds that films
+of high-aspect-ratio FePt grains with well-formed silicon oxide (SiOx) grain
+boundaries require the grading of the deposition temperature during film growth
+as well as the grading of the silicon oxide concentration. Well-isolated
+columnar grains of $\mathrm{L1_0-FePt}$ with an average height greater than 11
+nm and diameters less than 7 nm have been achieved. Transmission electron
+microscopy (TEM) analysis of the microstructures of samples produced under a
+variety of non-optimal conditions is presented to show how the microstructure
+of the films depends on each of the sputtering parameters.",2203.03496v1
+2022-04-04,Strain Effect on Air-Stability of Monolayer CrSe2,"The discovery of two dimensional (2D) magnetic materials has brought great
+research value for spintronics and data storage devices. However, their
+air-stability as well as the oxidation mechanism has not been unveiled, which
+limits their further applications. Here, by first-principles calculations, we
+carried out a detailed study on the oxidation process of monolayer CrSe2 and
+biaxial tensile strain effect. We found dissociation process of O2 on pristine
+CrSe2 sheet is an endothermic reaction with a reaction energy barrier of 0.53
+eV, indicating its thermodynamics stability. However, such a process becomes
+exothermic under a biaxial tensile strain reaching 1%, accompanying with a
+decreased reaction barrier, leading to reduced stability. These results
+manifest that in-plane strain plays a significant role in modifying
+air-stability in CrSe2 and shed considerable light on searching appropriate
+substrate to stabilize 2D magnetic materials.",2204.01400v2
+2022-09-29,Evaluation of Neel temperatures from fully self-consistent broken-symmetry GW and high-temperature expansion: application to cubic transition-metal oxides,"Using fully self-consistent thermal broken-symmetry GW we construct effective
+magnetic Heisenberg Hamiltonians for a series of transition metal oxides (NiO,
+CoO, FeO, MnO), capturing a rigorous but condensed description of the magnetic
+states. Then applying high-temperature expansion, we find the decomposition
+coefficients for spin susceptibility and specific heat. The radius of
+convergence of the found series determine the Neel temperature. The NiO, CoO,
+and FeO contain a small ferromagnetic interaction between the nearest neighbors
+(NN) and the dominant antiferromagnetic interaction between the next-nearest
+neighbors (NNN). For them the derived Neel temperatures are in a good agreement
+with experiment. The case of MnO is different because both NN and NNN couplings
+are antiferromagnetic and comparable in magnitude, for which the error in the
+estimated Neel temperature is larger, which is a signature of additional
+effects not captured by electronic structure calculations.",2209.14904v2
+2022-10-28,Electron-hole asymmetry of quantum collective excitations in high-$T_c$ copper oxides,"We carry out a systematic study of collective spin- and charge excitations
+for the canonical single-band Hubbard, $t$-$J$-$U$, and $t$-$J$ models of
+high-temperature copper-oxide superconductors, both on electron- and hole-doped
+side of the phase diagram. Recently developed variational wave function
+approach, combined with the expansion in inverse number of fermionic flavors,
+is employed. All three models exhibit a substantial electron-hole asymmetry of
+magnetic excitations, with a robust paramagnon emerging for hole-doping, in
+agreement with available resonant inelastic $x$-ray scattering data for the
+cuprates. The $t$-$J$ model yields additional high-energy peak in the magnetic
+spectrum that is not unambiguously identified in spectroscopy. For all
+considered Hamiltonians, the dynamical charge susceptibility contains a
+coherent mode for both hole- and electron doping, with overall bandwidth
+renormalization controlled by the on-site Coulomb repulsion. Away from the
+strong-coupling limit, the antiferromagnetic ordering tendency is more
+pronounced on electron-doped side of the phase diagram.",2210.16109v3
+2022-11-28,Hallmarks of non-trivial topology in Josephson junctions based on oxide nanochannels,"We investigate the topological properties of a Josephson junction obtained by
+constraining a two-dimensional electron gas at oxide interface to form a
+quasi-1D conductor. We reveal an anomalous critical current behaviour with a
+magnetic field applied perpendicular to the Rashba spin-orbit one. We relate
+the observed critical current enhancement at small magnetic fields with a
+non-trivial topology, accompanied by Majorana bound states (MBSs) pinned at the
+edges of the superconducting leads. Signatures of MBSs also include a sawtooth
+profile in the current-phase relation. Our findings allow to recognize
+fingerprints of topological superconductivity in non-centrosymmetric materials
+and confined systems with Rashba spin-orbit interaction, and to explain recent
+experimental observations for which a microscopic description is still lacking.",2211.15433v1
+2023-05-06,Giant magnetostriction in La2CoMnO6 synthesized by microwave irradiation,"Polycrystalline insulating ferromagnetic double perovskite La2CoMnO6
+possessing monoclinic structure and a high ferromagnetic Curie temperature (TC
+= 222 K) was rapidly synthesized ( 30 min) by irradiating stoichiometric
+mixture of oxides with the microwave. The sample exhibits negative
+magnetostriction, i.e., contraction of length along the magnetic field
+direction in the ferromagnetic state. At 10 K, the parallel magnetostriction
+does not show saturation up to a magnetic field of 50 kOe where it reaches 610
+ppm which is one of the highest values of magnetostriction found so far among
+perovskite oxides with 3d ions. The magnitude of magnetostriction decreases
+monotonically as the temperature increases and becomes negligible above TC. The
+giant magnetostriction in this double perovskite is suggested to originate from
+large spin-orbit coupling associated with Co2+ (d7) cation. The obtained
+magnetostriction value is comparable to 630 ppm in an identical composition
+obtained through solid-state reaction over several days in a conventional
+furnace which indicates the advantages of microwave-assisted synthesis in
+saving reaction time and electric power without deteriorating physical
+properties.",2305.03886v1
+2023-07-10,Porous CrO$_2$: a ferromagnetic half-metallic member in sparse hollandite oxide family,"A stable polymorph of CrO$_2$ is predicted using PBE+U method. The porous
+material is isostructural with $\alpha$-MnO$_2$ making it the second transition
+metal oxide in sparse hollandite group of materials. However, unlike the
+anti-ferromagnetic semiconducting character of the $\alpha$-MnO$_2$, it is
+found to be a ferromagnetic half-metal. At Fermi level, the hole pocket has
+ample contribution from O-2$p$ orbital, though, the electron pocket is mostly
+contributed by Cr-3$d_{xy}$ and Cr-3d$_{x^2-y^2}$. A combination of negative
+charge transfer through orbital mixing and extended anti-bonding state near
+Fermi level is responsible for the half-metallic ferromagnetic character of the
+structure. A comparative study of rutile and hollandite CrO$_2$ and hollandite
+MnO$_2$ structures delineate the interplay between structural, electronic and
+magnetic properties. The material shows a robust magnetic character under
+hydrothermal pressure, as well as, the band topology is conserved under
+uniaxial strain. Moderate magneto-crystalline anisotropy is observed and it
+shows a correspondence with the anisotropy of elastic constants.",2307.04584v1
+2023-08-13,The impact of the near-surface region on the interpretation of x-ray absorption spectroscopy,"Transition metal oxides (TMOs) exhibit a broad spectrum of electronic,
+magnetic, and optical properties, making them intriguing materials for various
+technological applications. Soft x-ray absorption spectroscopy (XAS) is widely
+used to study TMOs, shedding light on their chemical state, electronic
+structure, orbital polarization, element-specific magnetism, and more.
+Different XAS acquisition modes feature different information depth regimes in
+the sample. Here, we employ two XAS acquisition modes, having surface-sensitive
+versus bulk probing depths, on the prototypical TMO SrVO3. We illustrate and
+elucidate a strong apparent discrepancy between the different modes,
+emphasizing the impact of the near-surface region on the interpretation of XAS
+data. These findings highlight the importance of the acquisition mode selection
+in XAS analysis. Moreover, the results highlight the role of the near-surface
+region not only in the characterization of TMOs, but also in the design of
+future nanoscale oxide electronics.",2308.06724v1
+2023-11-14,Spin-phonon coupling suppressing the structural transition in perovskite-like oxide,"Multifunctional properties in quantum systems require the interaction between
+different degrees of freedom. As such, spin-phonon coupling emerges as an ideal
+mechanism to tune multiferroicity, magnetism, and magnetoelectric response. In
+this letter, we demonstrate and explain, based on theoretical and experimental
+analyses, an unusual manifestation of spin-phonon coupling, i.e., prevention of
+a ferroelastic structural transition, and locking of high-temperature R-3m
+phase in a magnetically frustrated perovskite-like oxide Ba2NiTeO6. We present
+Ba2NiTeO6 as a prototype example among its family where long-range
+antiferromagnetic structure couples with a low-frequency Eg mode (at 55 cm-1)
+that exhibits a large anharmonicity. Our findings establish that spin-phonon
+coupling clearly suppresses the phonon anharmonicity preventing the structural
+phase transition from the R-3m to the C2/m phase in Ba2NiTeO6.",2311.08028v1
+2024-02-09,Copper phosphate micro-flowers coated with indocyanine green and iron oxide nanoparticles for in vivo localization optoacoustic tomography and magnetic actuation,"Efficient drug delivery is a major challenge in modern medicine and
+pharmaceutical research. Micrometer-scale robots have recently been proposed as
+a promising venue to amplify precision of drug administration. Remotely
+controlled microrobots sufficiently small to navigate through microvascular
+networks can reach any part of the human body, yet real-time tracking is
+crucial for providing precise guidance and verifying successful arrival at the
+target. In vivo deep-tissue monitoring of individual microrobots is currently
+hampered by the lack of sensitivity and/or spatio-temporal resolution of
+commonly used clinical imaging modalities. We synthesized biocompatible and
+biodegradable copper phosphate micro-flowers loaded with indocyanine green and
+iron oxide nanoparticles to enable in vivo individual detection with
+localization optoacoustic tomography. We demonstrate magnetic actuation and
+optoacoustic tracking of these decorated micro-flowers at a per-particle level.
+Functional super-resolution imaging achieved via tracking intravenously
+injected particles provides a means of identifying microvascular targets and
+quantifying blood flow, while the versatile carrying capacity can be further
+exploited for transporting multiple types of drug formulations.",2402.06749v1
+2009-05-20,Measuring magnetic profiles at manganite surfaces with monolayer resolution,"The performance of manganite-based magnetic tunnel junctions (MTJs) has
+suffered from reduced magnetization present at the junction interfaces that is
+ultimately responsible for the spin polarization of injected currents; this
+behavior has been attributed to a magnetic ""dead layer"" that typically extends
+a few unit cells into the manganite. X-ray magnetic scattering in resonant
+conditions (XRMS) is one of the most innovative and effective techniques to
+extract surface or interfacial magnetization profiles with subnanometer
+resolution, and has only recently been applied to oxide heterostructures. Here
+we present our approach to characterizing the surface and interfacial
+magnetization of such heterostructures using the XRMS technique, conducted at
+the BEAR beamline (Elettra synchrotron, Trieste). Measurements were carried out
+in specular reflectivity geometry, switching the left/right elliptical
+polarization of light as well the magnetization direction in the scattering
+plane. Spectra were collected across the Mn L2,3 edge for at least four
+different grazing angles in order to better analyse the interference phenomena.
+The resulting reflectivity spectra have been carefully fit to obtain the
+magnetization profiles, minimizing the number of free parameters as much as
+possible. Optical constants of the samples (real and imaginary part of the
+refractive index) in the interested frequency range are obtained through
+absorption measurements in two magnetization states and subsequent
+Kramers-Kronig transformation, allowing quantitative fits of the magnetization
+profile at different temperatures. We apply this method to the study of
+air-exposed surfaces of epitaxial La2/3Sr1/3MnO3 (001) films grown on SrTiO3
+(001) substrates.",0905.3204v1
+2016-09-17,Magnetic-anisotropy induced spin blockade in a single-molecule transistor,"We present a new mechanism for a spin blockade effect associated with a
+change in the type of magnetic anisotropy over oxidation state in a single
+molecule transistor, by taking an example of an individual
+Eu$_{2}$(C$_{8}$H$_{8}$)$_{3}$ molecule weakly coupled to non-magnetic
+electrodes without linker groups. The molecule switches its magnetization
+direction from in-plane to out-of-plane when it is charged. In other words, the
+magnetic anisotropy of the molecule changes from easy plane to easy axis when
+the molecule is charged. By solving the master equation based on model
+Hamiltonian, we find that current through the molecule is highly suppressed at
+low bias independently of gate voltage due to the interplay between spin
+selection rules and the change in the type of magnetic anisotropy. Transitions
+between the lowest magnetic levels in successive charge states are forbidden
+because the magnetic levels differ by $|\Delta M| > 1/2$ due to the change in
+the type of magnetic anisotropy, although the total spins differ by $|\Delta
+S|=1/2$. This current suppression can be lifted by significant B field, and the
+threshold B field varies as a function of the field direction and the strength
+of magnetic anisotropy. The spin blockade effect shed light on switching the
+magnetization direction by non-spin-polarized current and on exploring effects
+of this property coupled to other molecular degrees of freedom.",1609.05269v1
+2017-07-13,Electric field controlled magnetic exchange bias and magnetic state switching at room temperature in Ga doped α-Fe2O3 oxide,"We have developed a new magnetoelectric material based on Ga doped
+{\alpha}-Fe2O3 in rhombohedral phase. The material is a canted ferromagnet at
+room temperature and showing magneto-electric properties. The experimental
+results of electric field controlled magnetic state provided a direct evidence
+of room temperature magnetoelectric coupling in Ga doped {\alpha}-Fe2O3 system.
+Interestingly, (un-doped) {\alpha}-Fe2O3 system does not exhibit any electric
+field controlled magnetic exchange bias shift, but Ga doped {\alpha}-Fe2O3
+system has shown an extremely high electric field induced magnetic exchange
+bias shift up to the value of 1120 Oe (positive). On the other hand, in a first
+time, we report the electric field controlled magnetic state switching both in
+{\alpha}-Fe2O3 and in Ga doped {\alpha}-Fe2O3 systems. The switching of
+magnetic state is highly sensitive to ON and OFF modes, as well as to the
+change of polarity of applied electric voltage during in-field magnetic
+relaxation experiments. The switching of magnetic state to upper level for
+positive electric field and to down level for negative electric field indicates
+that electric and magnetic orders are coupled in the Ga doped hematite system.
+Such material is of increasing demand in today for multifunctional applications
+in next generation magnetic sensor, switching, non-volatile memory and
+spintronic devices.",1707.04496v1
+2020-01-16,Tailoring magnetic order via atomically stacking 3d/5d electrons,"The ability to tune magnetic orders, such as magnetic anisotropy and
+topological spin texture, is desired in order to achieve high-performance
+spintronic devices. A recent strategy has been to employ interfacial
+engineering techniques, such as the introduction of spin-correlated interfacial
+coupling, to tailor magnetic orders and achieve novel magnetic properties. We
+chose a unique polar-nonpolar LaMnO3/SrIrO3 superlattice because Mn (3d)/Ir
+(5d) oxides exhibit rich magnetic behaviors and strong spin-orbit coupling
+through the entanglement of their 3d and 5d electrons. Through magnetization
+and magnetotransport measurements, we found that the magnetic order is
+interface-dominated as the superlattice period is decreased. We were able to
+then effectively modify the magnetization, tilt of the ferromagnetic easy axis,
+and symmetry transition of the anisotropic magnetoresistance of the
+LaMnO3/SrIrO3 superlattice by introducing additional Mn (3d) and Ir (5d)
+interfaces. Further investigations using in-depth first-principles calculations
+and numerical simulations revealed that these magnetic behaviors could be
+understood by the 3d/5d electron correlation and Rashba spin-orbit coupling.
+The results reported here demonstrate a new route to synchronously engineer
+magnetic properties through the atomic stacking of different electrons,
+contributing to future applications.",2001.05821v2
+2021-03-30,Magnetic Texture in Insulating Single Crystal High Entropy Oxide Spinel Films,"Magnetic insulators are important materials for a range of next generation
+memory and spintronic applications. Structural constraints in this class of
+devices generally require a clean heterointerface that allows effective
+magnetic coupling between the insulating layer and the conducting layer.
+However, there are relatively few examples of magnetic insulators which can be
+synthesized with surface qualities that would allow these smooth interfaces and
+precisely tuned interfacial magnetic exchange coupling which might be
+applicable at room temperature. In this work, we demonstrate an example of how
+the configurational complexity in the magnetic insulator layer can be used to
+realize these properties. The entropy-assisted synthesis is used to create
+single crystal (Mg0.2Ni0.2Fe0.2Co0.2Cu0.2)Fe2O4 films on substrates spanning a
+range of strain states. These films show smooth surfaces, high resistivity, and
+strong magnetic responses at room temperature. Local and global magnetic
+measurements further demonstrate how strain can be used to manipulate magnetic
+texture and anisotropy. These findings provide insight into how precise
+magnetic responses can be designed using compositionally complex materials that
+may find application in next generation magnetic devices.",2103.16722v1
+2023-10-09,Super-resolution diamond magnetic microscopy of superparamagnetic nanoparticles,"Scanning-probe and wide-field magnetic microscopes based on Nitrogen-Vacancy
+(NV) centers in diamond have enabled remarkable advances in the study of
+biology and materials, but each method has drawbacks. Here, we implement an
+alternative method for nanoscale magnetic microscopy based on optical control
+of the charge state of NV centers in a dense layer near the diamond surface. By
+combining a donut-beam super-resolution technique with optically detected
+magnetic resonance spectroscopy, we imaged the magnetic fields produced by
+single 30-nm iron-oxide nanoparticles. The magnetic microscope has a lateral
+spatial resolution of ~100 nm, and it resolves the individual magnetic dipole
+features from clusters of nanoparticles with interparticle spacings down to
+~190 nm. The magnetic feature amplitudes are more than an order of magnitude
+larger than those obtained by confocal magnetic microscopy due to the smaller
+characteristic NV-nanoparticle distance within nearby sensing voxels. We
+analyze the magnetic point-spread function and sensitivity as a function of the
+microscope's spatial resolution and identify sources of background fluorescence
+that limit the present performance, including diamond second-order Raman
+emission and imperfect NV charge-state control. Our method, which uses less
+than 10 mW laser power and can be parallelized by patterned illumination,
+introduces a new format for nanoscale magnetic imaging.",2310.05436v1
+2023-06-19,Onion-like Fe3O4/MgO/CoFe2O4 magnetic nanoparticles: new ways to control magnetic coupling between soft/hard phases,"The control of the magnetization inversion dynamics is one of the main
+challenges driving the design of new nanostructured magnetic materials for
+magnetoelectronic applications. Nanoparticles with onion-like architecture
+offer a unique opportunity to expand the possibilities allowing to combine
+different phases at the nanoscale and also modulate the coupling between
+magnetic phases by introducing spacers in the same structure. Here we report
+the fabrication, by a three-step high temperature decomposition method, of
+Fe3O4/MgO/CoFe2O4 onio-like nanoparticles and their detailed structural
+analysis, elemental compositional maps and magnetic response. The
+core/shell/shell nanoparticles present epitaxial growth and cubic shape with
+overall size of (29+-6) nm. These nanoparticles are formed by cubic iron oxide
+core of (22+-4) nm covered by two shells, the inner of magnesium oxide and the
+outer of cobalt ferrite of ~1 and ~2.5 nm of thickness, respectively. The
+magnetization measurements show a single reversion magnetization curve and the
+enhancement of the coercivity field, from HC~608 Oe for the Fe3O4/MgO to
+HC~5890 Oe to the Fe3O4/MgO/CoFe2O4 nanoparticles at T=5 K, ascribed to the
+coupling between both ferrimagnetic phases with a coupling constant of =2
+erg/cm2. The system also exhibits exchange bias effect, where the exchange bias
+field increases up to HEB~2850 Oe at 5 K accompanied with the broadening of the
+magnetization loop of HC~6650 Oe. This exchange bias effect originates from the
+freezing of the surface spins below the freezing temperature TF=32 K that
+pinned the magnetic moment of the cobalt ferrite shell.",2306.13108v1
+2017-01-28,Spin glass behavior in frustrated quantum spin system CuAl2O4 with a possible orbital liquid state,"CuAl2O4 is a normal spinel oxide having quantum spin, S=1/2 for Cu2+. It is a
+rather unique feature that the Cu2+ ions of CuAl2O4 sit at a tetrahedral
+position, not like the usual octahedral position for many oxides. At low
+temperatures, it exhibits all the thermodynamic evidence of a quantum spin
+glass. For example, the polycrystalline CuAl2O4 shows a cusp centered at ~2 K
+in the low-field dc magnetization data and a clear frequency dependence in the
+ac magnetic susceptibility while it displays logarithmic relaxation behavior in
+a time dependence of the magnetization. At the same time, there is a peak at
+~2.3 K in the heat capacity, which shifts towards higher temperature with
+magnetic fields. On the other hand, there is no evidence of new superlattice
+peaks in the high-resolution neutron powder diffraction data when cooled from
+40 to 0.4 K. This implies that there is no long-ranged magnetic order down to
+0.4 K, thus confirming a spin glass-like ground state for CuAl2O4.
+Interestingly, there is no sign of structural distortion either although Cu2+
+is a Jahn-Teller active ion. Thus, we claim that an orbital liquid state is the
+most likely ground state in CuAl2O4. Of further interest, it also exhibits a
+large frustration parameter, f = Theta_CW/Tm ~67, one of the largest values
+reported for spinel oxides. Our observations suggest that CuAl2O4 should be a
+rare example of a frustrated quantum spin glass with a good candidate for an
+orbital liquid state.",1701.08272v1
+2020-02-19,Ion-Irradiation-Induced Cobalt/Cobalt Oxide Heterostructures: Printing 3D Interfaces,"Interfaces separating ferromagnetic (FM) layers from non-ferromagnetic layers
+offer unique properties due to spin-orbit coupling and symmetry breaking,
+yielding effects such as exchange bias, perpendicular magnetic anisotropy,
+spin-pumping, spin-transfer torques, conversion between charge and spin
+currents and vice-versa. These interfacial phenomena play crucial roles for
+magnetic data storage and transfer applications, which require forming FM
+nano-structures embedded in non-ferromagnetic matrices. Here, we investigate
+the possiblity of creating such nano-structures by ion-irradiation. We study
+the effect of lateral confinement on the ion-irradiation-induced reduction of
+non-magnetic metal oxides (e.g., antiferro- or paramagnetic) to form
+ferromagnetic metals. Our findings are later exploited to form 3-dimensional
+magnetic interfaces between Co, CoO and Pt by spatially-selective irradiation
+of CoO/Pt multilayers. We demonstrate that the mechanical displacement of the O
+atoms plays a crucial role during the reduction from insulating,
+non-ferromagnetic cobalt oxides to metallic cobalt. Metallic cobalt yields both
+perpendicular magnetic anisotropy in the generated Co/Pt nano-structures, and,
+at low temperatures, exchange bias at vertical interfaces between Co and CoO.
+If pushed to the limit of ion-irradiation technology, this approach could, in
+principle, enable the creation of densely-packed, atomic scale ferromagnetic
+point-contact spin-torque oscillator (STO) networks, or conductive channels for
+current-confined-path based current perpendicular-to-plane giant
+magnetoresistance read-heads.",2002.08090v1
+2020-04-01,Perovskite-type cobalt oxide at the multiferroic Co/Pb Zr$_{0.2}$Ti$_{0.8}$O$_{3}$ interface,"Magnetic Tunnel Junctions whose basic element consists of two ferromagnetic
+electrodes separated by an insulating non-magnetic barrier have become
+intensely studied and used in non-volatile spintronic devices. Since ballistic
+tunnel of spin-polarized electrons sensitively depends on the chemical
+composition and the atomic geometry of the lead/barrier interfaces their proper
+design is a key issue for achieving the required functionality of the devices
+such as e.g. a high tunnel magneto resistance. An important leap in the
+development of novel spintronic devices is to replace the insulating barrier by
+a ferroelectric which adds new additional functionality induced by the
+polarization direction in the barrier giving rise to the tunnel electro
+resistance (TER). The multiferroic tunnel junction
+Co/PbZr$_{0.2}$Ti$_{0.8}$O$_{3}$/La$_{2/3}$Sr$_{1/3}$MnO$_3$ (Co/PZT/LSMO)
+represents an archetype system for which - despite intense studies - no
+consensus exists for the interface geometry and their effect on transport
+properties. Here we provide the first analysis of the Co/PZT interface at the
+atomic scale using complementary techniques, namely x-ray diffraction and
+extended x-ray absorption fine structure in combination with x-ray magnetic
+circular dichroism and ab-initio calculations. The Co/PZT interface consists of
+one perovskite-type cobalt oxide unit cell [CoO$_{2}$/CoO/Ti(Zr)O$_{2}$] on
+which a locally ordered cobalt film grows. Magnetic moments (m) of cobalt lie
+in the range between m=2.3 and m=2.7$\mu_{B}$, while for the interfacial
+titanium atoms they are small (m=+0.005 $\mu_{B}$) and parallel to cobalt which
+is attributed to the presence of the cobalt-oxide interface layers. These
+insights into the atomistic relation between interface and magnetic properties
+is expected to pave the way for future high TER devices.",2004.00489v1
+2007-03-20,Real-time observation of oxidation and photo-oxidation of rubrene thin films by spectroscopic ellipsometry,"We follow in real-time and under controlled conditions the oxidation of the
+organic semiconductor rubrene grown on SiO_2 using spectroscopic ellipsometry.
+We derive the complex dielectric function epsilon_1 + i epsilon_2 for pristine
+and oxidized rubrene showing that the oxidation is accompanied by a significant
+change of the optical properties, namely the absorption. We observe that
+photo-oxidation of rubrene is orders of magnitude faster than oxidation without
+illumination. By following different absorption bands (around 2.5eV and 4.0eV
+for pristine rubrene and around 4.9eV for oxidized rubrene) we infer that the
+observed photo-oxidation of these films involves non-Fickian diffusion
+mechanisms.",0703522v1
+2020-01-29,A Hybrid Density Functional Theory Benchmark Study on Lithium Manganese Oxides,"The lithium manganese oxide spinel Li$_x$Mn$_2$O$_4$, with $0\leq x\leq 2$,
+is an important example for cathode materials in lithium ion batteries.
+However, an accurate description of Li$_x$Mn$_2$O$_4$ by first-principles
+methods like density functional theory is far from trivial due to its complex
+electronic structure, with a variety of energetically close electronic and
+magnetic states. It was found that the local density approximation as well as
+the generalized gradient approximation (GGA) are unable to describe
+Li$_x$Mn$_2$O$_4$ correctly. Here, we report an extensive benchmark for
+different Li$_x$Mn$_y$O$_z$ systems using the hybrid functionals PBE0 and
+HSE06, as well as the recently introduced local hybrid functional PBE0r. We
+find that all of these functionals yield energetic, structural, electronic, and
+magnetic properties in good agreement with experimental data. The notable
+benefit of the PBE0r functional, which relies on on-site Hartree-Fock exchange
+only, is a much reduced computational effort that is comparable to GGA
+functionals. Furthermore, the Hartree-Fock mixing factors in PBE0r are smaller
+than in PBE0, which improves the results for (lithium) manganese oxides. The
+investigation of Li$_x$Mn$_2$O$_4$ shows that two Mn oxidation states, +III and
++IV, coexist. The Mn$^\text{III}$ ions are in the high-spin state and the
+corresponding MnO$_6$ octahedra are Jahn-Teller distorted. The ratio between
+Mn$^\text{III}$ and Mn$^\text{IV}$ and thus the electronic structure changes
+with the Li content while no major structural changes occur in the range from
+$x=0$ to $1$. This work demonstrates that the PBE0r functional provides an
+equally accurate and efficient description of the investigated
+Li$_x$Mn$_y$O$_z$ systems.",2001.10975v2
+1995-05-03,"Magnetic Transition Temperature of (La,Sr)MnO$_3$","Using the Kondo lattice model with classical spins in infinite dimension,
+  magnetic phase transition in the perovskite-type $3d$ transition-metal oxide
+(La,Sr)MnO$_3$ is theoretically studied. On the Bethe lattice, the
+self-consistency equations are solved exactly. Curie temperatures at the region
+of double-exchange ferromagnetism $0.1 < x < 0.25$ as well as the Neel
+temperature at $x=0$ are well reproduced quantitatively. Pressure effect on the
+Curie temperature is also discussed.",9505009v2
+1995-05-25,"Temperature Dependence of the Conductivity in (La,Sr)MnO$_3$","Using the Kondo lattice model with classical spins in infinite dimension,
+conductivity in the perovskite-type $3d$ transition-metal oxide (La,Sr)MnO$_3$
+is theoretically studied. Green's functions as well as spontaneous
+magnetization are obtained exactly on the Bethe lattice as a function of
+temperature. Conductivity is calculated from the Kubo formula. Below the Curie
+temperature, resistivity as a function of magnetization is in a good agreement
+with the experimental data. Anomalous behaviour in the temperature dependence
+of the optical conductivity observed in (La,Sr)MnO$_3$ is also explained.",9505117v1
+1996-05-21,Conductance through a Magnetic Domain Wall in Double Exchange System,"The conductance through a magnetic domain wall is calculated for the double
+exchange system as a function of energy and the width of the domain wall. It is
+shown that when the carrier density is low enough, the blockade is almost
+complete even for the smoothly varying spin configuration, i.e., large width of
+the domain wall. This result is applied to the manganese oxides.",9605130v1
+1997-12-10,Pseudo-gap behavior in dynamical properties of high-Tc cuprates,"Dynamical properties of 2D antiferromagnets with hole doping are investigated
+to see the effects of short range local magnetic order on the temperature
+dependence of the dynamical magnetic susceptibility. We show the pseudo-gap
+like behavior of the temperature dependence of the NMR relaxation rate. We also
+discuss implications of the results in relations to the observed spin gap like
+behavior of low-doped copper oxide high-$T_c$ superconductors.",9712104v2
+1998-09-21,First Principles Investigation of Ferromagnetism and Ferroelectricity in Bismuth Manganite,"We present results of local spin density approximation (LSDA) pseudopotential
+calculations for the perovskite structure oxide, bismuth manganite (BiMnO3).
+The origin of the differences between bismuth manganite and other perovskite
+manganites is determined by first calculating total energies and band
+structures of the high symmetry cubic phase, then sequentially lowering the
+magnetic and structural symmetry. Our results indicate that covalent bonding
+between bismuth cations and oxygen anions stabilizes different magnetic and
+structural phases compared with the rare earth manganites. This is consistent
+with recent experimental results showing enhancement of charge ordering in
+doped bismuth manganite.",9809282v1
+1999-06-03,Microwave Absorption Peaks : Signatures of Spin Dynamics in Cuprates,"We show that a common feature of temperature-dependent microwave absorption
+is the presence of absorption peaks. $ac$ loss peaks can arise when the
+internal $T$-dependent magnetic relaxation time crosses the measurement
+frequency. These features are observed in the \QTR{em}{insulating}
+($Sr_{x}Ca_{14-x}Cu_{24}O_{41}$, $La_{5/3}Sr_{1/3}NiO_{4}$ and
+$YBa_{2}Cu_{3}O_{6.0}$), \QTR{em}{pseudo-gap} ($T>T_{c}$ in underdoped
+$YBa_{2}Cu_{3}O_{7-\delta}$, $Hg:1223$ and $Hg:1201$) and
+\QTR{em}{superconducting} ($T<T_{c}$) states of the oxides. The commonality of
+these features suggests a magnetic (spin) mechanism, rather than a
+quasiparticle origin, for the so-called ``conductivity'' peaks observed in the
+cuprate superconductors.",9906053v2
+2000-01-20,Destruction of long-range antiferromagnetic order by hole doping,"We study the renormalization of the staggered magnetization of a
+two-dimensional antiferromagnet as a function of hole doping, in the framework
+of the t-J model. It is shown that the motion of holes generates decay of spin
+waves into ''particle-hole'' pairs, which causes the destruction of the
+long-range magnetic order at a small hole concentration. This effect is mainly
+determined by the coherent motion of holes. The value obtained for the critical
+hole concentration, of a few percent, is consistent with experimental data for
+the doped copper oxide high-Tc superconductors.",0001289v1
+2000-12-01,Theory for Phase Transitions in Insulating Vanadium Oxide,"We show that the recently proposed S=2 bond model with orbital degrees of
+freedom for insulating V$_{2}$O$_{3}$ not only explains the anomalous magnetic
+ordering, but also other mysteries of the magnetic phase transition. The model
+contains an additional orbital degree of freedom that exhibits a zero
+temperature quantum phase transtion in the Ising universality class.",0012019v3
+2001-01-18,C-axis Optical Sum Rule in Josephson Coupled Vortex State,"Observed violations of the $c$-axis optical sum rule can give important
+information on deviations from in-plane Fermi liquid behavior and on the nature
+of interlayer coupling between adjacent copper oxide planes. Application of a
+magnetic field perpendicular to these planes is another way to probe in-plane
+dynamics. We find that the optical sum rule is considerably modified in the
+presence of the $c$-axis magnetic field. Interlayer correlation of pancake
+vortices is involved in the sum rule modification; however, details of the
+vortex distribution in the plane are less important.",0101288v2
+2001-10-30,Localization corrections and small-q phonon-mediated unconventional superconductivity in the cuprates,"Taking into account the first localization corrections in the
+electron-impurity self-energy we study the effect of non-magnetic impurities on
+unconventional superconductivity (SC) mediated by small-q electron-phonon
+scattering. We show that when van Hove singularities are close to the Fermi
+level making the electronic system anisotropic as in the high-$T_c$ oxides,
+both the d-wave and s-wave states are sensitive to non-magnetic impurities and
+beyond a critical impurity concentration SC disappears in {\it both gap
+symmetry channels}. Impurity doping may induce a first order transition from
+d-wave to s-wave SC, but no saturation of the impuruty effect is reported due
+to the intrinsically anisotropic character of the localization corrections in
+this context.",0110637v1
+2002-05-27,"Polaron Effects on Superexchange Interaction: Isotope Shifts of $T_N$, $T_C$, and $T^*$ in Layered Copper Oxides","A compact expression has been obtained for the superexchange coupling of
+magnetic ions via intermediate anions with regard to polaron effects at both
+magnetic ions and intermediate anions. This expression is used to analyze the
+main features of the behavior of isotope shifts for temperatures of three types
+in layered cuprates: the Neel temperatures ($T_N$), critical temperatures of
+transitions to a superconducting state ($T_C$), and characteristic temperatures
+of the pseudogap in the normal state ($T^*$).",0205558v1
+2003-01-21,"Structure, Magnetic Properties and Spin-glass Behavior in La$sub{0.9}Tesub{0.1}MnOsub{3}$","In this study we report the structure, magnetic and electrical transport
+properties of pervoskite oxide La$sub{0.9}Tesub{0.1}MnOsub{3}$. This is a novel
+material with the space group R-3c, which shows the spin-glass-like feature at
+low temperature and has a good colossal magnetoresistance behavior. The
+magnetoresistance ratio is about 51% at 200 K in a field of 4 T. The XPS
+measurement suggests that Te ions are in the Te$up{4+}$ state, while Mn ions
+may be in the 2+ and 3+ valence state.",0301384v1
+2003-01-22,Magnetic light scattering in low-dimensional quantum spin systems,"An overview of one- and two-dimensional quantum spin systems based on
+transition-metal oxides and halides of current interest is given, such as
+spin-Peierls, spin-dimer, geometrically frustrated and ladder systems. The most
+significant and outstanding contributions of magnetic light scattering to the
+understanding of these materials are discussed and compared to results of other
+spectroscopies and thermodynamic measurements.",0301413v1
+2004-01-05,Enhancement of flux-line pinning in all-oxide superconductor/ferromagnet heterostructures,"We have studied the local critical current density, jc, in the superconductor
+thin film of bilayer structures consisting of YBa2Cu3O7 and the ferromagnets
+La2/3Ca1/3MnO3 and SrRuO3, respectively, by means of quantitative
+magneto-optics. A pronounced hysteresis of jc was observed which is ascribed to
+the magnetization state of the ferromagnetic layer. The results are discussed
+within the frame of magnetic vortex - wall interactions.",0401033v1
+2004-01-19,Magnetic Resonant excitations in High-{$\rm T_c$} superconductors,"The observation of an unusual spin resonant excitation in the superconducting
+state of various High-Tc ~copper oxides by inelastic neutron scattering
+measurements is reviewed. This magnetic mode % (that does not exist in
+conventional superconductors) is discussed in light of a few theoretical models
+and likely corresponds to a spin-1 collective mode.",0401328v2
+2004-02-12,Interpreting Stone's model of Berry Phases,"We show that a simple quantum-mechanical model, put forward by Stone sometime
+ago, affords description of site magnetoelectricity, a phenomenon which takes
+place in crystals (and molecular systems) when space inversion is locally
+broken and coexistence of electric and magnetic moments is permitted by the
+site point group. We demonstrate this by identifying a local order parameter,
+which is odd under both space inversion and time reversal. This order parameter
+(a magnetic quadrupole) characterises Stone's ground state. Our results
+indicate that the model, extended to a lattice of sites, could be relevant to
+the study of electronic properties of transition-metal oxides. A generalisation
+of Stone's hamiltonian to cover cases of different symmetry is also discussed.",0402339v1
+2004-04-07,Electric Field Effect in Diluted Magnetic Insulator Anatase Co:TiO2,"An external electric field induced reversible modulation of room temperature
+magnetic moment is achieved in an epitaxial and insulating thin film of
+dilutely cobalt-doped anatase TiO2. This first demonstration of electric field
+effect in any oxide based diluted ferromagnet is realized in a high quality
+epitaxial heterostructure of PbZr0.2Ti0.8O3/Co:TiO2/SrRuO3 grown on (001)
+LaAlO3. The observed effect, which is about 15% in strength in a given
+heterostructure, can be modulated over several cycles. Possible mechanisms for
+electric field induced modulation of insulating ferromagnetism are discussed.",0404172v1
+2004-09-15,Evidence for charged critical behavior in the pyrochlore superconductor RbOs2O6,"We analyze magnetic penetration depth data of the recently discovered
+superconducting pyrochlore oxide RbOs2O6. Our results strongly suggest that in
+RbOs2O6 charged critical fuctuations dominate the temperature dependence of the
+magnetic penetration depth near Tc. This is in contrast to the mean-field
+behavior observed in conventional superconductors and the uncharged critical
+behavior found in nearly optimally doped cuprate superconductors. However, this
+finding agrees with the theoretical predictions for charged criticality and the
+charged criticality observed in underdoped YBa2Cu3O6.59.",0409398v1
+2004-10-28,Power law resistivity behavior in 2D superconductors across the magnetic-field tuned superconductor-insulator transition,"We present the results of a systematic study of thin-films of amorphous
+indium-oxide near the superconductor-insulator transition. We show that the
+film's resistivity follows a simple, well-defined, power-law dependence on the
+perpendicular magnetic field. This dependence holds well into the insulating
+state. Our results indicate that vortices play a central role in the transport
+of our films in the superconducting as well as insulating phases.",0410724v2
+2005-02-06,Interplay of orbitally polarized and magnetically ordered phases in doped transition metal oxides,"We investigate the magnetic instabilities of the two-dimensional model of
+interacting e_g electrons for hole doping away from two electrons per site in
+the mean-field approximation. In particular, we address the occurrence of
+orbitally polarized states due to the inequivalent orbitals, and their
+interplay with ferromagnetic and antiferromagnetic spin order. The role played
+by the Hund's exchange coupling J_H and by the crystal field orbital splitting
+E_z in stabilizing one of the competing phases is discussed in detail.",0502158v1
+2005-07-06,A ferromagnetic oxide semiconductor as spin injection electrode in magnetic tunnel junction,"A magnetic tunnel junctions composed of room temperature ferromagnetic
+semiconductor rutile Ti1-xCoxO2-d and ferromagnetic metal Fe0.1Co0.9 separated
+by AlOx barrier showed positive tunneling magnetoresistance (TMR) with a ratio
+of ~11 % at 15 K, indicating that Ti1-xCoxO2-d can be used as a spin injection
+electrode. The TMR decreased with increasing temperature and vanished above 180
+K. TMR action at high temperature is likely prohibited by the inelastic
+tunneling conduction due to the low quality of the amorphous barrier layer
+and/or the junction interface.",0507137v1
+2005-07-12,Epitaxial magnetic perovskite nanostructures,"Precise arrays of sub-100 nm diameter nanodots are fabricated from magnetic
+oxide perovskites with the total coverage area up to 5 mm2. Epitaxial single
+crystal structure of the nanodots is demonstrated by cross-sectional TEM. Low
+temperature MFM study confirmed the ferromagnetism of the produced particles.",0507280v1
+2005-12-29,Effect of the Triplet State on the Random Telegraph Signal in Si n-MOSFETs,"We report on the static magnetic field dependence of the random telegraph
+signal (RTS) in a submicrometer silicon n-metal-oxide-semiconductor
+field-effect transistor. Using intense magnetic fields and $^{3}$He
+temperatures, we find that the characteristic time ratio changes by 3 orders of
+magnitude when the field increases from 0 to 12 T. Similar behaviour is found
+when the static field is either in-plane or perpendicular to the two
+dimensional electron gas. The experimental data can be explained by considering
+a model which includes the triplet state of the trapping center and the
+polarization of the channel electron gas.",0512692v1
+2007-06-05,Room-temperature ferromagnetism in nanoparticles of superconducting materials,"Nanoparticles of superconducting YBa2Cu3O7-delta (YBCO) (Tc = 91 K) exhibit
+ferromagnetism at room temperature while the bulk YBCO, obtained by heating the
+nanoparticles at high temperature (940 degree C), shows a linear magnetization
+curve. Across the superconducting transition temperature, the magnetization
+curve changes from that of a soft ferromagnet to a superconductor. Furthermore,
+our experiments reveal that not only nanoparticles of metal oxides but also
+metal nitrides such as NbN (Tc = 6 - 12 K) and delta-MoN (Tc ~ 6 K) exhibit
+room-temperature ferromagnetism.",0706.0634v1
+2007-06-22,Orbital and Spin Excitations in Cobalt Oxide,"By means of neutron scattering we have determined new branches of magnetic
+excitations in orbitally active CoO (TN=290 K) up to 15 THz and for
+temperatures from 6 K to 450 K. Data were taken in the (111) direction in six
+single-crystal zones. From the dependence on temperature and Q we have
+identified several branches of magnetic excitation. We describe a model for the
+coupled orbital and spin states of Co2+ subject to a crystal field and
+tetragonal distortion.",0706.3345v1
+2007-07-17,"How Large is the Intrinsic Flux Noise of a Magnetic Flux Quantum, of Half a Flux Quantum and of a Vortex-Free Superconductor?","This article addresses the question whether the magnetic flux of stationary
+vortices or of half flux quanta generated by frustrated superconducting rings
+is noisy. It is found that the flux noise generated intrinsically by a
+superconductor is, in good approximation, not enhanced by stationary vortices.
+Half flux quanta generated by $\pi$-rings are characterized by considerably
+larger noise.",0707.2550v1
+2007-08-24,"Observation of strong-coupling effects in a diluted magnetic semiconductor (Ga,Fe)N","A direct observation of the giant Zeeman splitting of the free excitons in
+(Ga,Fe)N is reported. The magnetooptical and magnetization data imply the
+ferromagnetic sign and a reduced magnitude of the effective p-d exchange energy
+governing the interaction between Fe^{3+} ions and holes in GaN, N_0 beta^(app)
+= +0.5 +/- 0.2 eV. This finding corroborates the recent suggestion that the
+strong p-d hybridization specific to nitrides and oxides leads to significant
+renormalization of the valence band exchange splitting.",0708.3296v1
+2008-11-20,Interlayer exchange coupling in Co2FeAl0.5Si0.5/Cr/Co2FeAl0.5Si0.5 trilayers,"Interlayer exchange couplings were examined for Co2FeAl0.5Si0.5(CFAS)/Cr/CFAS
+trilayered films grown on MgO (001) single crystal and thermally oxidized Si
+substrates. The films were (001) epitaxial on MgO and (110) textured
+polycrystalline on SiO2. Strong exchange couplings were observed for the films
+with the 1.5 nm thick Cr spacer layer. A 90 degree coupling is dominant in the
+(001) epitaxial film. In contrast, an antiparallel coupling exists in the
+polycrystalline one. The relationship of interlayer couplings with the
+structure is discussed.",0811.3278v1
+2009-07-25,Short-range magnetic order and temperature-dependent properties of cupric oxide,"The temperature dependence of the optical and magnetic properties of CuO were
+examined by means of hybrid density functional theory calculations. Our work
+shows that the spin exchange interactions in CuO are neither fully
+one-dimensional nor fully three-dimensional. The large temperature dependence
+of the optical band gap and the 63Cu nuclear quadrupole resonance frequency of
+CuO originate from the combined effect of a strong coupling between the spin
+order and the electronic structure and the progressive appearance of
+short-range order with temperature.",0907.4415v1
+2010-06-03,Relaxor characteristics at the interfaces of [NdMnO3/SrMnO3/LaMnO3] superlattices,"We have investigated the magnetic properties of transition metal oxide
+superlattices with broken inversion symmetry composed of three different
+antiferromagnetic insulators, [NdMnO3/SrMnO3/LaMnO3]. In the superlattices
+studied here, we identify the emergence of a relaxor, glassy-like behavior
+below spin glass temperature, T=36K. Our results offer the possibility to study
+and utilize magnetically metastable devices confined in nano-scale interfaces.",1006.0602v3
+2010-12-15,Giant Tunneling Electroresistance Effect Driven by an Electrically Controlled Spin Valve at a Complex Oxide Interface,"A giant tunneling electroresistance effect may be achieved in a ferroelectric
+tunnel junction by exploiting the magnetoelectric effect at the interface
+between a ferroelectric barrier and magnetic La1-xSrxMnO3 electrode. Using
+first-principles density functional theory we demonstrate that a few magnetic
+monolayers of La1-xSrxMnO3 near the interface act, in response to ferroelectric
+polarization reversal, as an atomic scale spin-valve by filtering
+spin-dependent current. This effect produces more than an order of magnitude
+change in conductance, and thus constitutes a giant resistive switching effect.",1012.3421v2
+2011-05-06,Radio frequency readout of electrically detected magnetic resonance in phosphorus-doped silicon MOSFETs,"We demonstrate radio frequency (RF) readout of electrically detected magnetic
+resonance in phosphorus-doped silicon metal-oxide field-effecttransistors
+(MOSFETs), operated at liquid helium temperatures. For the first time, the Si:P
+hyperfine lines have been observed using radio frequency reflectometry, which
+is promising for high-bandwidth operation and possibly time-resolved detection
+of spin resonance in donor-based semiconductor devices. Here we present the
+effect of microwave (MW) power and MOSFET biasing conditions on the EDMR
+signals.",1105.1235v1
+2012-07-30,Strain engineering magnetic frustration in perovskite oxide thin films,"Our first-principles results show that geometric frustration can be induced
+in thin films of multiferroic BiFeO3. We find that competing magnetic
+interactions occur in the so-called super-tetragonal phase of this material,
+which can be grown on strongly-compressive substrates. We show that the
+frustration level can be tuned by appropriately choosing the substrate; in
+fact, the three-dimensional spin order gets totally annihilated in a narrow
+range of epitaxial strains. We argue that the effects revealed here are not
+exclusive to BiFeO3, and predict that they also occur in multiferroic BiCoO3.",1207.6859v1
+2014-07-07,"Multiferroic hexagonal ferrites (h-RFeO$_3$, R=Y, Dy-Lu): an experimental review","Hexagonal ferrites (h-RFeO$_3$, R=Y, Dy-Lu) have recently been identified as
+a new family of multiferroic complex oxides.
+  The coexisting spontaneous electric and magnetic polarizations make
+h-RFeO$_3$ rare-case ferroelectric ferromagnets at low temperature.
+  Plus the room-temperature multiferroicity and predicted magnetoelectric
+effect, h-RFeO$_3$ are promising materials for multiferroic applications.
+  Here we review the structural, ferroelectric, magnetic, and magnetoelectric
+properties of h-RFeO$_3$.
+  The thin film growth is also discussed because it is critical in making high
+quality single crystalline materials for studying intrinsic properties.",1407.1798v1
+2015-07-11,Insulator/metal phase transition and colossal magnetoresistance in holographic model,"Within massive gravity, we construct a gravity dual for insulator/metal phase
+transition and colossal magnetoresistance (CMR) effect found in some manganese
+oxides materials. In heavy graviton limit, a remarkable
+magnetic-field-sensitive DC resistivity peak appears at the Curie temperature,
+where an insulator/metal phase transition happens and the magnetoresistance is
+scaled with the square of field-induced magnetization. We find that metallic
+and insulating phases coexist below the Curie point and the relation with the
+electronic phase separation is discussed.",1507.03105v2
+2016-03-29,Effect of delithiation on the dimer transition of the honeycomb-lattice ruthenate Li$_{2-x}$RuO$_3$,"The honeycomb-lattice ruthenate Li$_2$RuO$_3$ is made heavily Li-deficient by
+chemical oxidation by iodine. The delithiation triggers a different phase
+Li$_{2-x}$RuO$_3$, the ""D-phase"", with superlattice. For the first time we
+disclose the magnetic and structural properties of the D-phase in the
+dimer-solid state. The low temperature magnetic susceptibility and the bond
+lengths indicate a bonding configuration consisting of both Ru$^{4+}$-Ru$^{4+}$
+and Ru$^{5+}$-Ru$^{5+}$ dimers.",1603.08764v1
+2016-09-13,Spin-dependent transport and current modulation in a current-in-plane field-effect transistor,"We propose a current-in-plane spin-valve field-effect transistor
+(CIP-SV-FET), which is composed of a ferromagnet / nonferromagnet / ferromagnet
+trilayer structure and a gate electrode. This is a promising device alternative
+to spin metal-oxide-semiconductor field-effect transistors. Here, we fabricate
+a ferromagnetic-semiconductor GaMnAs-based CIP-SV-FET and demonstrate its basic
+operation of the resistance modulation both by the magnetization configuration
+and by the gate electric field. Furthermore, we present the
+electric-field-assisted magnetization reversal in this device.",1609.05859v1
+2020-07-04,Synthesis of FeNi tetrataenite phase by means of chemical precipitation,"FeNi L10 (tetrataenite) phase has great perspectives for hard magnetic
+materials production. In this paper it was synthesized in chemically
+co-precipitated FeNi nanopowder by means of thermal treating included cycling
+of oxidation and reduction processes at 320 {\deg}C. The presence of FeNi L10
+phase in the samples was confirmed by magnetic measurements and DSC analysis.",2007.02177v2
+2013-08-05,Sub-Piconewton Force Detection using Micron-Size Wire Deflections,"The mechanical properties of nanostructured wires obtained by co-assembly of
+iron oxide particles are studied. The intrinsic magnetic properties of the
+wires are used to induce and quantify the bending of the one-dimensional
+objects. From the relationship between the deflection and the magnitude of the
+magnetic field, the elastic rigidity and Young modulus of the wires are
+determined. Young moduli in the megapascal range are obtained and are
+consistent with sub-piconewton force detection.",1308.0893v1
+2012-01-16,Electric field control of chiral magnetic domains in the high-temperature multiferroic CuO,"We have studied the high temperature multiferroic cupric oxide using
+polarized neutron diffraction as a function of temperature and applied electric
+field. We find that the chiral domain population can be varied using an
+external electric field applied along the b axis. Using representation analysis
+we derive the incommensurate magnetic structure in the multiferroic phase. The
+origin of the magnetoelectric coupling is consistent with models based on the
+inverse Dzyaloshinskii-Moriya interaction, but is different from the simple
+cycloidal mechanism.",1201.3309v1
+2018-07-02,Enhanced thermopower via spin-state modification,"We investigated the effect of pressure on the magnetic and thermoelectric
+properties of Sr$_{3.1}$Y$_{0.9}$Co$_{4}$O$_{10+\delta }$. The magnetization is
+reduced with the application of pressure, reflecting the spin-state
+modification of the Co$^{3+}$ ions into the nonmagnetic low-spin state.
+Accordingly, with increasing pressure, the Seebeck coefficient is enhanced,
+especially at low temperatures, at which the effect of pressure on the spin
+state becomes significant. These results indicate that the spin-orbital entropy
+is a key valuable for the thermoelectric properties of the strongly correlated
+cobalt oxides.",1807.00551v1
+2019-11-06,Disclosing antiferromagnetism in tetragonal Cr2O3 by electrical measurements,"The tetragonal phase of chromium (III) oxide, although unstable in the bulk,
+can be synthesized in epitaxial heterostructures. The theoretical investigation
+by density functional theory predicts an antiferromagnetic ground state for
+this compound. We demonstrate experimentally antiferromagnetism up to 40 K in
+ultrathin films of t-Cr2O3 by electrical measurements exploiting interface
+effect within a neighboring ultrathin Pt layer. We show that magnetotransport
+in Pt is affected by both spin-Hall magnetoresistance and magnetic proximity
+effect while we exclude any role of magnetism for the low-temperature
+resistance anomaly observed in Pt.",1911.02596v1
+2020-06-22,Magnetic excitations of Sr$_3$Ir$_2$O$_7$ observed by inelastic neutron scattering measurement,"In this short note, we report on the first inelastic neutron scattering (INS)
+study on high-energy magnetic excitations in Sr$_3$Ir$_2$O$_7$. We observed
+excitations between $\sim$80 meV and $\sim$180 meV. The peak position of the
+excitations is consistent with the dispersion of a single magnon determined by
+resonant inelastic X-ray scattering (RIXS) measurement. Thus, our results
+demonstrate that INS and RIXS observe identical excitations in iridate oxides,
+as in La$_2$CuO$_4$.",2006.12074v2
+2021-07-07,Origin of nonlinear magnetoelectric response in rare-earth orthoferrite perovskite oxides,"We report a theoretical study of the non-linear magnetoelectric response of
+GdFeO$_3$ through an analytical approach combined with a Heisenberg model which
+is fitted against first-principles calculations. Our theory reproduces the
+non-linear change of polarization under applied magnetic field reported
+experimentally such that it allows to analyze the origin of the large responses
+in the different directions. We show that the non-linear character of the
+response in these materials originates from the fact that the antiferromagnetic
+order of Gd atoms changes non-linearly with respect to the applied magnetic
+field. Our model can be generalized to other materials in which the
+antiferromagnetic ordering breaks inversion symmetry.",2107.03228v1
+2022-02-03,TiO2 with Super Narrow Bandgap Achieved in One-Step Single-Mode Magnetic Microwave Induced Plasma Treatment,"TiO2 with super narrow bandgap (1.1 eV~) are successfully synthesized via a
+facile and novel one-step single-mode magnetic microwave induced plasma
+treatment. The selectively surface Ti3+-doping on obtained TiO2 as trapping
+centers which significantly restrain the photo-excited carrier recombination
+and achieve the enhancement of visible-light photocatalytic performance. In
+addition, the surface chemical composition of TiOx is precisely controlled in a
+wide region of 1.19 < x < 1.92 during one-step reaction. A detailed XPS
+analysis reveals that the surface formed Ti3+ shows highly thermal/chemical
+stability even through high-temperature treatment (~800 oC) in oxidative
+atmosphere and photocatalytic reaction.",2202.01368v1
+2022-07-25,Broken-symmetry self-consistent GW approach: degree of spin contamination and evaluation of effective exchange couplings in solid antiferromagnets,"We adopt a broken-symmetry strategy for evaluating effective magnetic
+constants $J$ within the fully self-consistent GW method. To understand the
+degree of spin contamination present in broken-symmetry periodic solutions, we
+propose several size-extensive quantities that demonstrate that the
+unrestricted self-consistent GW preserves well the broken-symmetry character of
+the unrestricted Hartree--Fock solutions. The extracted $J$ are close to the
+ones obtained from multireference wave-function calculations. In this paper, we
+establish a robust computational procedure for finding magnetic coupling
+constants from self-consistent GW calculations and apply it to solid
+antiferromagnetic nickel and manganese oxides.",2207.12064v1
+2023-06-12,Wide Range Thin-FIlm Ceramic Metal-Alloy Thermometers with Low Magnetoresistance,"Many thermal measurements in high magnetic fields require thermometers that
+are sensitive over a wide temperature range, are low mass, have a rapid thermal
+response, and have a minimal, easily correctable magnetoresistance. Here we
+report the development of a new granular-metal oxide ceramic composite (cermet)
+for this purpose formed by co-sputtering of the metallic alloy nichrome
+Ni$_{0.8}$Cr$_{0.2}$ and the insulator silcon dioxide SiO$_2$. The resulting
+thin films are sensitive enough to be used from room temperature down to below
+100 mK in magnetic fields up to at least 35 tesla.",2306.06950v2
+2023-03-06,Pressure-Dependent Layer-by-Layer Oxidation of ZrS2(001) Surface,"Understanding oxidation mechanisms of layered semiconducting transition-metal
+dichalcogenide (TMDC) is important not only for controlling native oxide
+formation but also for synthesis of oxide and oxysulfide products. Here,
+reactive molecular dynamics simulations show that oxygen partial pressure
+controls not only the ZrS2 oxidation rate but also the oxide morphology and
+quality. We find a transition from layer-by-layer oxidation to
+amorphous-oxide-mediated continuous oxidation as the oxidation progresses,
+where different pressures selectively expose different oxidation stages within
+a given time window. While the kinetics of the fast continuous oxidation stage
+is well described by the conventional Deal-Grove model, the layer-by-layer
+oxidation stage is dictated by reactive bond-switching mechanisms. This work
+provides atomistic details and a potential foundation for rational
+pressure-controlled oxidation of broad TMDC materials.",2303.03220v1
+2000-02-16,"Magnetic pair-breaking in superconducting (Ba,K)BiO_3 investigated by magnetotunneling","The de Gennes and Maki theory of gapless superconductivity for dirty
+superconductors is used to interpret the tunneling measurements on the strongly
+type-II high-Tc oxide-superconductor Ba1-xKxBiO3 in high magnetic fields up to
+30 Tesla. We show that this theory is applicable at all temperatures and in a
+wide range of magnetic fields starting from 50 percent of the upper critical
+field Bc2. In this magnetic field range the measured superconducting density of
+states (DOS) has the simple energy dependence as predicted by de Gennes from
+which the temperature dependence of the pair-breaking parameter alpha(T), or
+Bc2(T), has been obtained. The deduced temperature dependence of Bc2(T) follows
+the Werthamer-Helfand-Hohenberg prediction for classical type-II
+superconductors in agreement with our previous direct determination. The
+amplitudes of the deviations in the DOS depend on the magnetic field via the
+spatially averaged superconducting order parameter which has a square-root
+dependence on the magnetic field. Finally, the second Ginzburg-Landau parameter
+kappa2(T) has been determined from the experimental data.",0002241v1
+2000-03-14,"Magnetic and electrical resistance behaviour of the oxides, Ca$_{3-x}$Y$_x$LiRuO$_6$ (x= 0.0, 0.5 and 1.0)","We have investigated the magnetic and electrical resistance behaviour of
+  Ca$_{3-x}$Y$_x$LiRuO$_6$. The parent compound exhibits magnetic ordering from
+Ru sublattice at a rather high temperature, 113 K. Though the paramagnetic
+  Curie temperature ($\theta$$_p$) is negative indicative of antiferromagnetic
+ordering, the large magnitude (-250 K) of $\theta$$_p$ reveals complex nature
+of the magnetism in this compound. Ru ions appear to be in the pentavalent
+state. We note that the N\'eel temperature undergoes only a marginal reduction
+by Y substitution. All these compositions are found to be insulators and thus
+the electron doping does not result in metallicity. Thus the overall magnetic
+and transport behaviour are found to be essentially insensitive to Y
+substitution for Ca, a finding which may favour the idea of
+quasi-one-dimensional magnetism in these compounds.",0003227v1
+2002-09-17,Sr2V3O9 and Ba2V3O9: quasi one-dimensional spin-systems with an anomalous low temperature susceptibility,"The magnetic behaviour of the low-dimensional Vanadium-oxides Sr2V3O9 and
+Ba2V3O9 was investigated by means of magnetic susceptibility and specific heat
+measurements. In both compounds, the results can be very well described by an
+S=1/2 Heisenberg antiferromagnetic chain with an intrachain exchange of J = 82
+K and J = 94 K in Sr2V3O9 and Ba2V3O9, respectively. In Sr2V3O9,
+antiferromagnetic ordering at T_N = 5.3 K indicate a weak interchain exchange
+of the order of J_perp ~ 2 K. In contrast, no evidence for magnetic order was
+found in Ba2V3O9 down to 0.5 K, pointing to an even smaller interchain
+coupling. In both compounds, we observe a pronounced Curie-like increase of the
+susceptibility below 30 K, which we tentatively attribute to a staggered field
+effect induced by the applied magnetic field. Results of LDA calculations
+support the quasi one-dimensional character and indicate that in Sr2V3O9, the
+magnetic chain is perpendicular to the structural one with the magnetic
+exchange being transferred through VO4 tetrahedra.",0209409v1
+2003-06-25,Static magnetic response of clusters in Co_{0.2}Zn_{0.8}Fe_{1.95}Ho_{0.05}O_{4} spinel oxide,"Earlier investigation of Co_{0.2}Zn_{0.8}Fe_{1.95}Ho_{0.05}O_{4} spinel has
+shown the existence of ""super-ferromagnetic "" clusters containing Fe^{3+} and
+Ho^{3+} ions along with small size clusters of Fe^{3+} ions (Bhowmik et al, J.
+Magn. Magn. Mater. {247}, 83 (2002)). Here, We report the static magnetic
+response of these clusters. The experimental data suggests some interesting
+magnetic features, such as, enhancement of magnetization; re-entrant magnetic
+transitions with paramagnetic to ferromagnetic state below 225 K and
+ferromagnetic to spin glass state below 120 K; appearance of field induced
+ferromagnetism. We also observe an unusual maximum in the thermoremanent
+magnetization (TRM) vs temperature data. Our measurements suggest that this
+unusuality in TRM is related to the blocking of ""super-ferromagnetic"" clusters
+,out of the ferromagnetic state, along their local anisotropy axis.",0306653v1
+2004-06-18,Magnetic Superconducting Heterostructures,"Heterogeneous magnetic superconducting systems (HMSS) represent a new class
+of nanostructures. They are made of ferromagnetic (FM) and superconducting (SC)
+pieces separated by thin layers of insulating oxides. In contrast to the case
+of a homogeneous ferromagnetic superconductor studied during the last two
+decades, the two order parameters, the magnetization and the SC electron
+density do not suppress each other. In HMSS, the interaction between the two
+order parameters is due to the magnetic field created by the magnetic and SC
+textures. Strong interaction of the FM and SC systems not only gives rise to a
+new class of novel phenomena and physical effects, but also shows the important
+technological promise of devices whose transport properties can be easily tuned
+by comparatively weak magnetic fields.",0406443v1
+2005-03-16,The atomic-start description of NiO,"We have calculated magnetic properties and the electronic structure of NiO
+both in the paramagnetic and in magnetically-ordered state as well as
+zero-temperature properties and thermodynamics within the strongly-correlated
+crystal-field approach. It is in agreement with a Mott's suggestion that NiO is
+an insulator due to strong electron correlations. We have quantified
+crystal-field, spin-orbit and magnetic interactions of the Ni2+ ion in NiO. We
+have obtained that E_dd >> E_CF(=2.0 eV) >> E_{s-o}(=0.29 eV) > E_mag(=0.07
+eV). The orbital moment of 0.54 mu_B amounts at 0 K, in the
+magnetically-ordered state, to about 20% of the total moment (2.53 mu_B). Our
+studies indicate that it is the highest time to ""unquench"" orbital magnetic
+moment in 3d solid-state physics and the necessity to take always into account
+strong intra-atomic correlations among d electrons and the intra-atomic
+spin-orbit coupling.
+  Pacs: 75.25.+z, 75.10.Dg
+  Keywords: Crystalline Electric Field, 3d oxides, magnetism, spin-orbit
+coupling NiO",0503407v1
+2007-02-05,Existence of two electronic states in Sr4Ru3O10 at low temperatures,"We report measurements on in-plane resistivity, thermopower, and
+magnetization as a function of temperature and magnetic fields on single
+crystalline Sr4Ru3O10 grown by the floating zone method. As the temperature was
+lowered to below around 30 K, the in-plane and c-axis resistivities and the
+thermopower were found to exhibit a step feature accompanied by hysteresis
+behavior when the in-plane field was swept up and down from below 10 kOe to
+above 20 kOe. The sharp increase in the thermopower with increasing in-plane
+magnetic field at low temperatures has not been observed previously in layered
+transition metal oxides. Comparing with magnetization data, we propose that the
+step feature marks the transition between the two different electronic states
+in Sr4Ru3O10. We propose that the alignment of domains by the in-plane magnetic
+field is responsible to the emergence of the new electronic states in high
+applied in-plane magnetic field.",0702093v1
+2007-11-02,Magnetism without magnetic impurities in oxides ZrO2 and TiO2,"We perform a theoretical study of the magnetism induced in transition metal
+dioxides ZrO2 and TiO2 by substitution of the cation by a vacancy or an
+impurity from the groups 1A or 2A of the periodic table, where the impurity is
+either K or Ca. In the present study both supercell and embedded cluster
+methods are used. It is demonstrated that the vacancy and the K-impurity leads
+to a robust induced magnetic moment on the surrounding O-atoms for both the
+cubic ZrO2 and rutile TiO2 host crystals. On the other hand it is shown that
+Ca-impurity leads to a non magnetic state. The native O-vacancy does not induce
+a magnetic moment in the host dioxide crystal.",0711.0280v1
+2007-12-18,Observation of electromagnon excitations in the BiFe0$_3$ spiral magnet,"Recently, oxide multiferroics have attracted much attention due to their
+large magnetoelectric effect which allows the tuning of magnetic properties
+with electric field and vice versa and open new venues for future spintronic
+applications such as multiple-state memory devices with dual magnetic and
+electric control. BiFeO$_3$ (BFO) belongs to this new class of materials and
+shows both ferroelectric and antiferromagnetic orders at room temperature with
+a large electric polarizationassociated with a cycloidal spiral magnetic
+ordering. The incommensurate magnetic order induces magnon zone folding and
+allows investigations by optical probes of unusual spin waves which couples to
+optical phonons, the so called ""`electromagnons""'. Here, we unravel for the
+first time the electromagnon spectra of BFO by means low energy inelastic light
+scattering technique. We show the existence of two species of electromagnons
+corresponding to spin wave excitations in and out of the cycloidal plane. The
+present observations present an unique opportunity to study the interplay
+between ferroelectric and magnetic orders.",0712.3044v1
+2008-01-09,Magnetic coupling in highly-ordered NiO/Fe3O4(110): Ultrasharp magnetic interfaces vs. long-range magnetoelastic interactions,"We present a laterally resolved X-ray magnetic dichroism study of the
+magnetic proximity effect in a highly ordered oxide system, i.e. NiO films on
+Fe3O4(110). We found that the magnetic interface shows an ultrasharp
+electronic, magnetic and structural transition from the ferrimagnet to the
+antiferromagnet. The monolayer which forms the interface reconstructs to
+NiFe2O4 and exhibits an enhanced Fe and Ni orbital moment, possibly caused by
+bonding anisotropy or electronic interaction between Fe and Ni cations. The
+absence of spin-flop coupling for this crystallographic orientation can be
+explained by a structurally uncompensated interface and additional
+magnetoelastic effects.",0801.1468v1
+2009-07-23,Large specific absorption rates in the magnetic hyperthermia properties of metallic iron nanocubes,"We report on the magnetic hyperthermia properties of chemically synthesized
+ferromagnetic 11 and 16 nm Fe(0) nanoparticles of cubic shape displaying the
+saturation magnetization of bulk iron. The specific absorption rate measured on
+16 nm nanocubes is 1690+-160 W/g at 300 kHz and 66 mT. This corresponds to
+specific losses-per-cycle of 5.6 mJ/g, largely exceeding the ones reported in
+other systems. A way to quantify the degree of optimization of any system with
+respect to hyperthermia applications is proposed. Applied here, this method
+shows that our nanoparticles are not fully optimized, probably due to the
+strong influence of magnetic interactions on their magnetic response. Once
+protected from oxidation and further optimized, such nano-objects could
+constitute efficient magnetic cores for biomedical applications requiring very
+large heating power.",0907.4063v3
+2009-09-24,"Magnetic, Thermal, and Transport Properties of the Mixed Valent Vanadium Oxides LuV4O8 and YV4O8","LV4O8 (L = Yb, Y, Lu) compounds are reported to crystallize in a structure
+similar to that of the orthorhombic CaFe2O4 structure-type, and contain four
+inequivalent V sites arranged in zigzag chains. We confirm the structure and
+report the magnetic, thermal, and transport properties of polycrystalline YV4O8
+and LuV4O8. A first-order like phase transition is observed at 50 K in both
+YV4O8 and LuV4O8. The symmetry remains the same with the lattice parameters
+changing discontinously. The structural transition in YV4O8 leads to partial
+dimerization of the V atoms resulting in a sudden sharp drop in the magnetic
+susceptibility. The V spins that do not form dimers order in a canted
+antiferromagnetic state. The magnetic susceptibility of LuV4O8 shows a sharp
+peak at ~ 50 K. The magnetic entropies calculated from heat capacity versus
+temperature measurements indicate bulk magnetic transitions below 90 K for both
+YV4O8 and LuV4O8.",0909.4572v2
+2010-08-25,"Carrier-Concentration Dependence of the Pseudogap Ground State of Superconducting Bi2Sr2-xLaxCuO6+delta Revealed by 63,65Cu-Nuclear Magnetic Resonance in Very High Magnetic Fields","We report the results of the Knight shift by 63,65Cu-nuclear-magnetic
+resonance (NMR) measurements on single-layered copper-oxide
+Bi2Sr2-xLaxCuO6+delta conducted under very high magnetic fields up to 44 T. The
+magnetic field suppresses superconductivity completely and the pseudogap ground
+state is revealed. The 63Cu-NMR Knight shift shows that there remains a finite
+density of states (DOS) at the Fermi level in the zero-temperature limit, which
+indicates that the pseudogap ground state is a metallic state with a finite
+volume of Fermi surface. The residual DOS in the pseudogap ground state
+decreases with decreasing doping (increasing x) but remains quite large even at
+the vicinity of the magnetically ordered phase of x > 0.8, which suggests that
+the DOS plunges to zero upon approaching the Mott insulating phase.",1008.4277v1
+2011-06-29,Hysteretic magnetoresistance and thermal bistability in a magnetic two-dimensional hole system,"Colossal negative magnetoresistance and the associated field-induced
+insulator-to-metal transition, the most characteristic features of magnetic
+semiconductors, are observed in n-type rare earth oxides and chalcogenides,
+p-type manganites, n-type and p-type diluted magnetic semiconductors (DMS) as
+well as in quantum wells of n-type DMS. Here, we report on magnetostransport
+studies of Mn modulation-doped InAs quantum wells, which reveal a magnetic
+field driven and bias voltage dependent insulator-to-metal transition with
+abrupt and hysteretic changes of resistance over several orders of magnitude.
+These phenomena coexist with the quantised Hall effect in high magnetic fields.
+We show that the exchange coupling between a hole and the parent Mn acceptor
+produces a magnetic anisotropy barrier that shifts the spin relaxation time of
+the bound hole to a 100 s range in compressively strained quantum wells. This
+bistability of the individual Mn acceptors explains the hysteretic behaviour
+while opening prospects for information storing and processing. At high bias
+voltage another bistability, caused by the overheating of electrons10, gives
+rise to abrupt resistance jumps.",1106.5832v1
+2012-03-21,High-field magnetization and magnetoresistance of the $A$-site ordered perovskite oxide CaCu$_{3}$Ti$_{4-x}$Ru$_{x}$O$_{12}$~($0 \le x \le 4$),"We have measured high-field magnetization and magnetoresistance of
+polycrystalline samples of the A-site ordered perovskite CaCu3Ti4-xRuxO12 (x=0
+- 4) utilizing a non-destructive pulsed magnet. We find that the magnetization
+for x=0.5, 1.0 and 1.5 is nonlinear, and tends to saturate in high fields. This
+is highly nontrivial because the magnetization for x=0 and 4 is linear in
+external field up to the highest one. We have analyzed this field dependence
+based on the thermodynamics of magnetic materials, and propose that the
+external fields delocalize the holes on the Cu2+ ions in order to maximize the
+entropy. This scenario is qualitatively consistent with a large
+magnetoresistance of -70% observed at 4.2 K at 52 T for x=1.5.",1203.4660v1
+2013-01-23,Electric-field-induced magnetization changes in Co/Al2O3 granular multilayers,"We study experimentally the effect of electric field on the magnetization of
+Co/Al2O3 granular multilayers. We observe two distinct regimes: (a) low-field
+regime when the net magnetization of the system changes in a reversible way
+with the applied electric field and (b) high-field regime when the
+magnetization decreases irreversibly. The former is attributed to the changes
+in the relative 3d-orbital occupation of the minority and majority bands in the
+Co granules. A theoretical model has been developed to explain the electric
+field induced changes in the band structure of the granular system and hence
+the magnetic moment. The latter result may be understood assuming the electric
+field induces oxygen migration from Al2O3 to the Co granules, since an increase
+in oxidation state of the Co granules is shown, through ab-initio calculations,
+to give rise to a reduced magnetization of the system.",1301.5396v1
+2013-03-19,X-ray absorption spectroscopy and magnetic circular dichroism studies of L1_0-Mn-Ga thin films,"Tetragonally distorted \(\rm{Mn}_{3-x}\rm{Ga}_x\) thin films with \(0.1< x <
+2\) show a strong perpendicular magnetic anisotropy and low magnetization and
+thus have the potential to serve as electrodes in spin transfer torque magnetic
+random access memory. Because a direct capping of these films with MgO is
+problematic due to oxide formation, we examined the influence of a CoFeB
+interlayer, and of two different deposition methods for the MgO barrier on the
+formation of interfacial MnO for \(\rm{Mn}_{62}\rm{Ga}_{38}\) by element
+specific X-ray absorption spectroscopy (XAS) and magnetic circular dichroism
+(XMCD). A highly textured L1\(_0\) crystal structure of the Mn-Ga films was
+verified by X-ray diffraction (XRD) measurements. For samples with e-beam
+evaporated MgO barrier no evidence for MnO was found, whereas in samples with
+magnetron sputtered MgO MnO was detected, even for the thickest interlayer
+thickness. Both XAS and XMCD measurements showed an increasing interfacial MnO
+amount with decreasing CoFeB interlayer thickness. Additional element specific
+full hysteresis loops determined an out-of-plane magnetization axis for the Mn
+and Co, respectively.",1303.4648v2
+2014-10-10,"Two dimensional magnetic correlation in the unconventional corrugated layered oxides (Ba,Sr)$_4$Mn$_3$O$_{10}$","Both Ba$_4$Mn$_3$O$_{10}$ and Sr$_4$Mn$_3$O$_{10}$ crystallize in an
+orthorhombic crystal structure consisting of corrugated layers containing
+Mn$_3$O$_{12}$ polydedra. The thermal variation of magnetic susceptibility of
+the compositions consists of a broad hump like feature indicating the presence
+of low dimensional magnetic correlation. We have systematically investigated
+the magnetic data of these compounds and found that the experimental results
+match quite well with the two dimensional Heisenberg model of spin-spin
+interaction. The two dimensional nature of the magnetic spin-spin interaction
+is supported by the low temperature heat capacity data of Ba$_4$Mn$_3$O$_{10}$.
+Interestingly, both the samples show dielectric anomaly near the magnetic
+ordering temperature indicating multiferroic behavior.",1410.2715v1
+2015-04-06,Quantifying the complex permittivity and permeability of magnetic nanoparticles,"The complex permittivity and permeability of superparamagnetic iron-oxide
+nanoparticles has been quantified using a circular waveguide assembly with a
+static magnetic field to align the nanoparticle's magnetization. The high
+sensitivity of the measurement provides the precise resonant feature of
+nanoparticles. The complex permeability in the vicinity of ferromagnetic
+resonance (FMR) is in agreement with the nanoparticle's measured magnetization
+via conventional magnetometry. A rigorous and self-consistent measure of
+complex permittivities and permeabilities of nanoparticles is crucial to
+ascertain accurately the dielectric behaviour as well as the frequency response
+of nanoparticle magnetization, necessary ingredients when designing and
+optimizing magnetic nanoparticles for biomedical applications.",1504.01404v1
+2015-05-18,Magnetic state dependent transient lateral photovoltaic effect in patterned ferromagnetic metal-oxide-semiconductor films,"We investigate the influence of an external magnetic field on the magnitude
+and dephasing of the transient lateral photovoltaic effect (T-LPE) in
+lithographically patterned Co lines of widths of a few microns grown over
+naturally passivated p-type Si(100). The T-LPE peak-to-peak magnitude and
+dephasing, measured by lock-in or through the characteristic time of laser OFF
+exponential relaxation, exhibit a notable influence of the magnetization
+direction of the ferromagnetic overlayer. We show experimentally and by
+numerical simulations that the T-LPE magnitude is determined by the Co
+anisotropic magnetoresistance. On the other hand, the magnetic field dependence
+of the dephasing could be described by the influence of the Lorentz force
+acting perpendiculary to both the Co magnetization and the photocarrier drift
+directions. Our findings could stimulate the development of fast position
+sensitive detectors with magnetically tuned magnitude and phase responses.",1505.04580v1
+2015-09-16,Charge-Induced Spin Torque in Anomalous Hall Ferromagnets,"We demonstrate that spin-orbit coupled electrons in a magnetically doped
+system exert a spin torque on the local magnetization, without a flowing
+current, when the chemical potential is modulated in a magnetic field. The spin
+torque is proportional to the anomalous Hall conductivity, and its effective
+field strength may overcome the Zeeman field. Using this effect, the direction
+of the local magnetization is switched by gate control in a thin film. This
+charge-induced spin torque is essentially an equilibrium effect, in contrast to
+the conventional current-induced spin-orbit torque, and, thus, devices using
+this operating principle possibly have higher efficiency than the conventional
+ones. In addition to a comprehensive phenomenological derivation, we present a
+physical understanding based on a model of a Dirac-Weyl semimetal, possibly
+realized in a magnetically doped topological insulator. The effect might be
+realized also in nanoscale transition materials, complex oxide ferromagnets,
+and dilute magnetic semiconductors.",1509.04799v1
+2020-07-03,From Weak Antilocalization to Kondo Scattering in a Magnetic Complex Oxide Interface,"Quantum corrections to electrical resistance can serve as sensitive probes of
+the magnetic landscape of a material. For example, interference between
+time-reversed electron paths gives rise to weak localization effects, which can
+provide information about the coupling between spins and orbital motion, while
+the Kondo effect is sensitive to the presence of spin impurities. Here we use
+low-temperature magnetotransport measurements to reveal a transition from weak
+antilocalization (WAL) to Kondo scattering in the quasi-two-dimensional
+electron gas formed at the interface between SrTiO$_3$ and the Mott insulator
+NdTiO$_3$. This transition occurs as the thickness of the NdTiO$_3$ layer is
+increased. Analysis of the Kondo scattering and WAL points to the presence of
+atomic-scale magnetic impurities coexisting with extended magnetic regions that
+affect transport via a strong magnetic exchange interaction. This leads to
+distinct magnetoresistance behaviors that can serve as a sensitive probe of
+magnetic properties in two dimensions.",2007.01853v1
+2013-08-24,Emerging magnetism and electronic phase separation at titanate interfaces,"The emergence of magnetism in otherwise nonmagnetic compounds and its
+underlying mechanisms have become the subject of intense research. Here we
+demonstrate that the nonmagnetic oxygen vacancies are responsible for an
+unconventional magnetic state common for titanate interfaces and surfaces.
+Using an effective multiorbital modelling, we find that the presence of
+localized vacancies leads to an interplay of ferromagnetic order in the
+itinerant t2g band and complex magnetic oscillations in the
+orbitally-reconstructed eg-band, which can be tuned by gate fields at oxide
+interfaces. The magnetic phase diagram includes highly fragmented regions of
+stable and phase-separated magnetic states forming beyond nonzero critical
+defect concentrations.",1308.5319v1
+2012-04-11,Frustrated magnets and quantum paramagnetic phases at finite temperature,"We develop a general framework, which combines exact diagonalization in small
+clusters with a density matrix variational principle, to study frustrated
+magnets at finite temperature. This thermodynamic hierarchical mean-field
+technique is used to determine the phase diagram and magnetization process of
+the three-dimensional spin-1/2 $J_1$-$J_2$ antiferromagnet on a stacked square
+lattice. Its non-magnetic phase exhibits a thermal crossover from a quantum to
+a classical paramagnet at a temperature $T=T_0$ which can be extracted from
+thermodynamic measurements. At low temperature an applied magnetic field
+stabilizes, through order-by-disorder, a variety of phases with non-trivial
+spin textures and a magnetization plateau at half-saturation which continuously
+disappears at $T\sim T_0$. Our results are relevant for frustrated vanadium
+oxides.",1204.2559v2
+2014-05-05,A single crystal high-temperature pyrochlore antiferromagnet,"We report the magnetic characterization of the frustrated transition metal
+pyrochlore NaCaCo$_2$F$_7$. This material has high spin Co$^{2+}$ in CoF$_6$
+octahedra in a pyrochlore lattice, and disordered non-magnetic Na and Ca on the
+large-atom sites in the structure. Large crystals grown by the floating zone
+method were studied. The magnetic susceptibility is isotropic, the Co moment is
+larger than the spin-only value, and in spite of the large Curie Weiss theta
+(-140 K), freezing of the spin system, as characterized by peaks in the ac and
+dc susceptibility and specific heat, does not occur until around 2.4 K. This
+yields a frustration index of f = $-\theta_{CW}$/$T_f$ $\approx$ 56, an
+indication that the system is highly frustrated. The observed entropy loss at
+the freezing transition is low, indicating that magnetic entropy remains
+present in the system at 0.6 K. The compound may be the realization of a
+frustrated pyrochlore antiferromagnet with weak bond disorder. The high
+magnetic interaction strength, strong frustration, and the availability of
+large single crystals makes NaCaCo$_2$F$_7$ an interesting alternative to rare
+earth oxide pyrochlores for the study of geometric magnetic frustration in
+pyrochlore lattices.",1405.0956v1
+2015-12-19,Verification of Anderson superexchange in MnO via magnetic pair distribution function analysis and \textit{ab initio} theory,"We present temperature-dependent atomic and magnetic pair distribution
+function (PDF) analysis of neutron total scattering measurements of
+antiferromagnetic MnO, an archetypal strongly correlated transition-metal
+oxide. The known antiferromagnetic ground-state structure fits the
+low-temperature data closely with refined parameters that agree with
+conventional techniques, confirming the reliability of the newly developed
+magnetic PDF method. The measurements performed in the paramagnetic phase
+reveal significant short-range magnetic correlations on a $\sim$1~nm length
+scale that differ substantially from the low-temperature long-range spin
+arrangement. \textit{Ab initio} calculations using a self-interaction-corrected
+local spin density approximation of density functional theory predict magnetic
+interactions dominated by Anderson superexchange and reproduce the measured
+short-range magnetic correlations to a high degree of accuracy. Further
+calculations simulating an additional contribution from a direct exchange
+interaction show much worse agreement with the data. The Anderson superexchange
+model for MnO is thus verified by experiment and confirmed by \textit{ab
+initio} theory.",1512.06270v2
+2017-07-03,Heavy-mass magnetic modes in pyrochlore iridates due to dominant Dzyaloshinskii-Moriya interaction,"Materials with strong spin-orbit interactions are presently a main target in
+the search for systems with novel magnetic properties. Magnetic anisotropies
+can be very large in such compounds, ranging from strongly frustrated Kitaev
+exchange in honeycomb iridates and the associated spin-liquid states to robust
+antisymmetric couplings in square-lattice Sr_2IrO_4 . Here we predict from ab
+initio quantum chemistry calculations that another highly unusual regime is
+realized in pyrochlore iridium oxides: the nearest-neighbor Heisenberg
+interaction can vanish whilst the antisymmetric Dzyaloshinskii- Moriya exchange
+reaches values as large as 5 meV, a result which challenges common notions and
+existing phenomenological models of magnetic superexchange. The resulting spin
+excitation spectra reveal a very flat magnon dispersion in the Nd- and Tb-based
+pyrochlore iridates, suggesting the possibility of using these modes to store
+magnetic information. Indeed the magnetization dynamics indicates that these
+modes are unable to propagate out of the excitation region.",1707.00500v1
+2017-12-06,Dynamic quantum kagome ice,"The search for two dimensional quantum spin liquids, exotic magnetic states
+with an entangled ground state remaining disordered down to zero temperature,
+has been a great challenge in frustrated magnetism during the last decades.
+Recently, fractionalized excitations, called spinons, emerging from these
+states, have been evidenced in kagome and triangular antiferromagnets. In
+contrast, quantum ferromagnetic spin liquids in two dimensions, namely quantum
+kagome ices, have been less investigated, yet their classical counterparts
+exhibit amazing properties, magnetic monopole crystals as well as magnetic
+fragmentation. Here we show that, by applying a magnetic field on the
+pyrochlore oxide Nd$_2$Zr$_2$O$_7$, which has been shown to develop three
+dimensional quantum magnetic fragmentation in zero field, we are able to reduce
+the dimension of the system and to create a dynamic kagome ice state. Our
+results open the way to the observation of the quantum kagome ice state which
+was recently investigated theoretically.",1712.02418v2
+2018-10-30,Magnetic field sensing with the kinetic inductance of a high-$T_\mathrm{c}$ superconductor,"We carry out an experimental feasibility study of a magnetic field sensor
+based on the kinetic inductance of the high-$T_\mathrm{c}$ superconductor
+yttrium barium copper oxide. We pattern thin superconducting films into
+radio-frequency resonators that feature a magnetic field pick-up loop. At 77 K
+and for film thicknesses down to 75 nm, we observe the persistence of screening
+currents that modulate the loop kinetic inductance. According to the
+experimental results the device concept appears attractive for sensing
+applications in ambient magnetic field environments. We report on a device with
+a magnetic field sensitivity of 4 pT/Hz${}^{1/2}$, an instantaneous dynamic
+range of 11 $\mu$T, and operability in magnetic fields up to 28 $\mu$T.",1810.12725v1
+2020-04-01,Suppression of magnetic phase transition at high magnetic field and non-Debye's nature of nano-crystalline Gd$_2$CoMnO$_6$: a detail study of physical properties,"Structural, magnetization, phonon behavior, and dielectric response of
+nano-crystalline Gd$_2$CoMnO$_6$ have been presented in this paper. The study
+shows that the material crystallizes in $\textit{P2$_1$/n}$ phase group of the
+monoclinic crystal structure. XPS measurement shows Co$^{2+}$ and Mn$^{4+}$
+oxidation states are present in the sample. Magnetization study reveals that
+the sample undergoes a ferromagnetic ordering of Co$^{2+}$ and Mn$^{4+}$
+magnetic ions around $T_c$ $\sim$132 K. However we have seen that with the
+application of external magnetic field the phase transition is largely
+suppressed. Raman study reveals the presence spin-phonon coupling in
+Gd$_2$CoMnO$_6$. Dielectric study reveals that the sample shows large
+dielectric constant and strong dispersion in mid frequency range. The
+dielectric loss shows there are two relaxation processes present in the
+material with different relaxation time and which are driven by thermally
+activated relaxation mechanics. Further, the Nyquist plot and AC conductivity
+study show that this sample is non-Debye's in nature.",2004.00737v1
+2018-06-14,Magnetic inhomogeneity in the copper pseudochalcogenide CuNCN,"Copper carbodiimide, CuNCN, is a geometrically frustrated nitrogen-based
+analogue of cupric oxide, whose magnetism remains ambiguous. Here, we employ a
+combination of local-probe techniques, including $^{63,\, 65}$Cu nuclear
+quadrupole resonance, $^{13}$C nuclear magnetic resonance and muon spin
+rotation to show that the magnetic ground state of the Cu$^{2+}$ ($S=1/2$)
+spins is frozen and disordered. Moreover, these complementary experiments
+unequivocally establish an onset of intrinsically inhomogeneous magnetic state
+at $T_h=80$ K. Below $T_h$, the low-temperature frozen component coexist with
+the remnant high-temperature dynamical component down to $T_l = 20$ K, where
+the latter finally ceases to exist. Based on a scaling of internal magnetic
+fields of both components we conclude that the two components coexist on a
+microscopic level.",1806.05486v2
+2018-07-24,Forced- and Self-Rotation of Magnetic Nanorods Assembly at the Cell Membrane: A Biomagnetic Torsion Pendulum,"In order to give insights into how anisotropic nano-objects interact with
+living cell membranes, and possibly self-assemble, we designed magnetic
+nanorods with average size around 100 nm x 1$\mu$m by assembling iron oxide
+nanocubes within a polymeric matrix under a magnetic field. We then explored
+the nano-bio interface at the cell membrane under the influence of a rotating
+magnetic field. We observed a complex structuration of the nanorods intertwined
+with the membranes. Unexpectedly, after a magnetic rotating stimulation, the
+resulting macrorods were able to rotate freely for multiple rotations,
+revealing the creation of a bio-magnetic torsion pendulum.",1807.08994v1
+2019-03-01,Temperature dependence of the magnetization of La$_{0.67}$Sr$_{0.33}$MnO$_3$ thin films on LaAlO$_3$,"The authors report on the interplay between magnetically ordered phases with
+temperature and magnetic field across compressively strained interfaces of thin
+La0.67Sr0.33MnO3 films on LaAlO3 substrates. From the temperature dependence of
+the magnetization and resistivity studies, they find two distinct temperature
+regimes, where this interplay is clearly exhibited. They ascribe this to the
+strain induced Jahn-Teller-like distortion that favors the stabilization of the
+d3z2-r2 orbitals and enhances superexchange between adjoining Mn atoms. The
+temperature and field sweep of the magnetization and electronic transport lead
+to a hybridization between the closely spaced energy levels of d3z2-r2 and
+dx2-y2 orbitals leading to the coexistence of ferromagnetic and
+antiferromagnetic phases. Such an observation, not reported earlier, offers new
+routes for the design and study of magnetic textures in variously strained
+interfaces between perovskite oxides.",1903.00319v1
+2019-03-26,"Magnetic and magnetoelectric properties of $A$FeF$_5$ ($A$ = Ca, Sr) spin-chain compounds","Fluorides in general are characterized by big variety of crystal structures,
+whereas those containing transition metals also often show sizable magnetic
+properties. The tendency of fluorine to form linear chain structures in many
+cases results in low-dimensional magnetism. Despite the plethora of magnetic
+phenomena in fluorides, their magnetoelectric properties are less studied than
+those of oxides. In the present work we theoretically study the magnetic and
+magnetoelectric properties of spin-chain compounds CaFeF$_5$ and SrFeF$_5$. The
+density functional theory is employed for determination of magnetic exchange
+constants, which are then used in Monte Carlo calculations. The symmetry
+analysis reveals that CaFeF$_5$ does not show magnetoelectric properties,
+whereas SrFeF$_5$ is a multiferroic.",1903.10828v2
+2019-04-01,Experimental creation and annihilation of nonvolatile magnetic skyrmions using voltage control of magnetic anisotropy without an external magnetic field,"In this work, we utilize voltage controlled magnetic anisotropy (VCMA) to
+manipulate magnetic skyrmions that are fixed in space. Memory devices based on
+this strategy can potentially be of smaller footprint and better energy
+efficiency than current-controlled motion-based skyrmionic devices. To
+demonstrate VCMA induced manipulation of skyrmions, we fabricate
+antiferromagnet/ferromagnet/oxide heterostructure films where skyrmions can be
+stabilized without any external magnetic field due to the presence of exchange
+bias. These isolated skyrmions were annihilated by applying a voltage pulse
+that increased PMA. On the other hand, decreasing PMA promoted formation of
+more skyrmions. Furthermore, skyrmions can be created from chiral domains by
+increasing PMA of the system. To corroborate our experimental observations, we
+performed micromagnetic simulation. The proposed method could potentially lead
+to novel skyrmion-based memory devices.",1904.00701v1
+2020-03-21,Magnetic Particle Spectroscopy: A Short Review of Applications,"Magnetic particle spectroscopy (MPS), also called magnetization response
+spectroscopy, is a novel measurement tool derived from magnetic particle
+imaging (MPI). It can be interpreted as a zero-dimensional version of MPI
+scanner. MPS was primarily designed for characterizing superparamagnetic iron
+oxide nanoparticles (SPIONs) regarding their applicability for MPI. In recent
+years, it has evolved into an independent, versatile, highly sensitive,
+inexpensive platform for biological and biomedical assays, cell labeling and
+tracking, and blood analysis. MPS has also developed into an auxiliary tool for
+magnetic imaging and hyperthermia by providing high spatial and temporal
+mappings of temperature and viscosity. Furthermore, other MPS-based
+applications are being explored such as magnetic fingerprints for product
+tracking and identification in supply chains. There are a variety of novel
+MPS-based applications being reported and demonstrated by many groups. In this
+short review, we highlighted some of the representative applications based on
+MPS platform, thereby providing a roadmap of this technology and our insights
+for researchers in this area.",2003.09577v1
+2020-05-29,Plasma-induced magnetic patterning of FePd thin films without and with exchange bias,"We demonstrate control of magnetic domain structures in continuous FePd thin
+films by patterning their surfaces with plasma treatment. The Fe-oxide layer
+formed on the surface upon ambient exposure of the FePd alloy thin film grown
+on an Al$_2$O$_3$(0001) substrate was patterned into microstructures by e-beam
+lithography followed by O$_2$- or Ar-plasma treatment. Microscopic pinning of
+magnetic domain walls in the thin films is then observed by magneto-optic Kerr
+effect microscopy, with the magnetic field needed to reverse the magnetization
+of the plasma-treated areas being larger than that for the untreated areas. An
+intriguing competition between the uniaxial anisotropy and the exchange bias is
+also observed in the system. This study demonstrates that patterning of the
+film surface with plasma treatment can be an easy and efficient method for
+sophisticated engineering of magnetic structures in thin films, and therefore
+has potential application in developing future data-storage and spintronic
+devices.",2005.14497v1
+2020-10-21,Strong tuning of magnetism and electronic structure by spin orientation,"To efficiently manipulate magnetism is a key physical issue for modern
+condensed matter physics, which is also crucial for magnetic functional
+applications. Most previous relevant studies rely on the tuning of spin
+texture, while the spin orientation is often negligible. As an exception,
+spin-orbit coupled $J_{\rm eff}$ states of $4d$/$5d$ electrons provide an ideal
+platform for emergent quantum effects. However, many expectations have not been
+realized due to the complexities of real materials. Thus the pursuit for more
+ideal $J_{\rm eff}$ states remains ongoing. Here a near-ideal $J_{\rm
+eff}$=$3/2$ Mott insulating phase is predicted in the family of hexachloro
+niobates, which avoid some common drawbacks of perovskite oxides. The local
+magnetic moment is nearly compensated between spin and orbital components,
+rendering exotic recessive magnetism. More interestingly, the electronic
+structure and magnetism can be strongly tuned by rotating spin axis, which is
+rare but crucial for spintronic applications.",2010.10741v1
+2021-10-26,"Structure and magnetic studies of geometrically frustrated disordered pyrochlores A$_{2}$Zr$_{2}$O$_{7}$: (A = Eu, Gd, Er)","The spin ice system Dy$_{2}$Ti$_{2}$O$_{7}$ exhibits strong
+frequency-dependent spin-freezing at $\sim$ 16 K temperature. Although it has
+been a matter of discussion for years, the origin of this unusual spin freezing
+is still unknown. The replacement of Ti with isovalent Zr leads to the dynamic
+magnetic ground state at low temperatures in Dy$_{2}$Zr$_{2}$O$_{7}$ and
+prevents the formation of high-temperature spin freezing. Interestingly the
+high-temperature spin freezing re-emerges in the presence of the magnetic
+field. In this direction, we have studied a series of disordered pyrochlore
+oxides A$_{2}$Zr$_{2}$O$_{7}$ (A = Eu, Gd, Er) and compared their crystal
+structure, magnetic, and heat capacity behavior with that of
+Dy$_{2}$Zr$_{2}$O$_{7}$ and Ho$_{2}$Zr$_{2}$O$_{7}$ systems. Our study shows
+that depending on the disordered parameter, the spin-freezing behavior can be
+retained by slowing down the spin dynamic with a suitable choice of the
+magnetic field. We observe that unlike titanates, modification at the rare
+earth site does not make considerable change in the magnetic ground state of
+these zirconates compounds.",2110.13573v1
+2022-03-19,Spin wave excitation and directional propagation in presence of magnetic charges in square artificial spin ice,"Artificial spin ice is a special class of engineered lattice of highly shape
+anisotropic single domain magnetic nanostructures which is used as one of the
+model systems to study the spin ice behavior observed in pyrochlore oxides. The
+nanomagnets interact via dipolar interaction which results in correlated
+magnetization dynamics exhibiting macroscopic spin configuration states. Here,
+we exploit the interplay of underlying magnetic state and external bias field
+orientation to study controlled spin wave propagation in square Artificial Spin
+Ice (sASI) by performing detailed micromagnetic simulations. We report that
+careful selection of vertices with local magnetic charges can effectively
+direct the anisotropic spin wave in presence of an external field. Further, we
+explore the influence of local charges due to the excited state in
+even-coordinated vertices as well as uncompensated charges due to
+odd-coordinated vertices on spin wave behavior. Our studies suggest that there
+is no perceptible difference on spin wave dynamical behavior due to the origin
+of local magnetic charge in sASI. Our results of controlled and directional
+spin wave propagation in sASI system may be useful for low-power consumption
+based all magnonic on-chip devices.",2203.10345v1
+2022-12-28,First-principles study of spin orbit coupling contribution to anisotropic magnetic interaction,"Anisotropic magnetic exchange interactions lead to a surprisingly rich
+variety of the magnetic properties. Considering the spin orbit coupling (SOC)
+as perturbation, we extract the general expression of a bilinear spin
+Hamiltonian, including isotropic exchange interaction, antisymmetric
+Dzyaloshinskii-Moriya (DM) interaction and symmetric $\Gamma $ term. Though it
+is commonly believed that the magnitude of the DM and $\Gamma $ interaction
+correspond to the first and second order of SOC strength $% \lambda $
+respectively, we clarify that the term proportional to $\lambda ^{2}$ also has
+contribution to DM interaction. Based on combining magnetic force theorem and
+linear-response approach, we have presented the method of calculating
+anisotropic magnetic interactions, which now has been implemented in the open
+source software WienJ. Furthermore, we introduce another method which could
+calculate the first and second order SOC contribution to the DM interaction
+separately, and overcome some shortcomings of previous methods. Our methods are
+successfully applied to several typical weak ferromagnets for $3d$, $4d$ and
+$5d$ transition metal oxides. We also predict the conditions where the DM
+interactions proportional to $\lambda $ are symmetrically forbidden while the
+DM interactions proportional to $\lambda ^{2}$ are nonzero, and believe that it
+is widespread in certain magnetic materials.",2212.13963v1
+2023-01-25,Discovery of spin glass in maple-leaf lattice Na2Mn3O7,"Geometrically frustrated magnetism is commonly studied in triangular and
+Kagome lattices. A rare lattice which exhibits frustration is obtained by
+depleting 1/7 of the sites from a triangular lattice and is called a maple-leaf
+lattice. We report the magnetic properties of an oxide material with a
+maple-leaf lattice: Na2Mn3O7. Structural studies suggest slight lattice
+distortion and density functional theory predicts energetic near-degeneracy
+between ferromagnetism and antiferromagnetic phases which points towards
+competing magnetic orderings at low temperatures. In addition, from our
+magnetic studies, we discovered a non-equilibrium spin state below ~50 K. The
+bifurcation of field-cooled and zero-field-cooled magnetization curves,
+hysteresis of ~16 kOe at 2 K, and time-dependent magnetization response is
+consistent with a spin glass state. To our knowledge this is the first report
+of such a state in materials with a MLL. This is a promising discovery towards
+using spin glass to transport angular momentum or spins for applications low
+power spintronics.",2301.10399v1
+2023-02-26,Emergence of net magnetization by magnetic-field-biased diffusion in antiferromagnetic L1$_0$ NiMn,"NiMn is a collinear antiferromagnet with high magneto crystalline anisotropy
+($K_2=-9.7\times10^5\;\text{J m}^{-3}$). Through magnetic annealing of NiMn
+with excess Ni, strongly pinned magnetic moments emerge due to an imbalance in
+the distribution of Ni in the antiferromagnetic Mn-sublattices. The results are
+explained with a model of magnetic-field-biased diffusion, supported by ab
+initio calculations. Another observation is the oxidation of Mn at the surface,
+causing an enrichment of Ni in the sub-surface region. This leads to an
+additional ferromagnetic response appearing in the magnetization measurements,
+which can be removed by surface polishing.",2302.13387v1
+2023-12-04,Negative Magnetization and Magnetic Ordering of Rare Earth and Transition Metal Sublattices in NdFe0.5Cr0.5O3,"We investigate the effect of alloying at the 3d transition metal site of a
+rare-earth-transition metal oxide, by considering NdFe0.5Cr0.5O3 alloy with two
+equal and random distribution of 3d ions, Cr and Fe, interacting with an early
+4f rare earth ion, Nd. Employing temperature- and field-dependent magnetization
+measurements, temperature-dependent x-ray diffraction, neutron powder
+diffraction, and Raman spectroscopy, we characterize its structural and
+magnetic properties. Our study reveals bipolar magnetic switching (arising from
+negative magnetization) and magnetocaloric effect which underline the potential
+of the studied alloy in device application. The neutron diffraction study shows
+the absence of spin reorientation transition over the entire temperature range
+of 1.5-320 K, although both parent compounds exhibit spin orientation
+transition. We discuss the microscopic origin of this curious behavior. The
+neutron diffraction results also reveal the ordering of Nd spins at an
+unusually high temperature of about 40 K, which is corroborated by Raman
+measurements.",2312.01595v1
+2024-01-26,Efficient Control of Magnetization Dynamics Via W/CuO$_\text{x}$ Interface,"Magnetization dynamics, which determine the speed of magnetization switching
+and spin information propagation, play a central role in modern spintronics.
+Gaining its control will satisfy the different needs of various spintronic
+devices. In this work, we demonstrate that the surface oxidized Cu
+(CuO$_\text{x}$) can be employed for the tunability of magnetization dynamics
+of ferromagnet (FM)/heavy metal (HM) bilayer system. The capping CuO$_\text{x}$
+layer in CoFeB/W/CuO$_\text{x}$ trilayer reduces the magnetic damping value in
+comparison with the CoFeB/W bilayer. The magnetic damping even becomes lower
+than that of the CoFeB/CuO$_\text{x}$ by ~ 16% inferring the stabilization of
+anti-damping phenomena. Further, the reduction in damping is accompanied by a
+very small reduction in the spin pumping-induced output DC voltage in the
+CoFeB/W/CuO$_\text{x}$ trilayer. The simultaneous observation of anti-damping
+and spin-to-charge conversion can be attributed to the orbital Rashba effect
+observed at the HM/CuO$_\text{x}$ interface. Our experimental findings
+illustrate that the cost-effective CuO$_\text{x}$ can be employed as an
+integral part of modern spintronics devices owing to its rich underneath
+spin-orbital physics.",2401.14708v1
+1997-11-13,The singlet-triplet magnetism and induced spin fluctuations in the high-$T_c$ copper oxides,"High-$T_c$ cuprates like $La_{2-x}Sr_{x}CuO_{4}$ and $YBa_{2-x}Cu_{3}O_{6+x}$
+are considered as a system of the electron and hole polar pseudo-Jahn-Teller
+$CuO_{4}$ centers $[{CuO}_{4}^{7-}]_{JT}$ and $[CuO_{4}^{5-}]_{JT}$,
+respectively, or a system of the local bosons moving in a lattice of the hole
+centers. Ground manifold of the polar centers includes three terms $^{1}A_{1g}$
+(Zhang-Rice singlet), $^{1}E_{u}$, $^{3}E_{u}$ with different spin
+multiplicity, orbital degeneracy and parity that provides an unconventional
+multi-mode behaviour of the cuprates. The spin subsystem of the copper oxides
+within the polar Jahn-Teller $CuO_{4}$ centers model is a two-component spin
+liquid and corresponds to a singlet-triplet magnet with possible noncollinear
+spin configurations. In the framework of a modified mean field approximation
+some kinds of spin ordering are discussed including as a trivial singlet or
+triplet states as a pure quantum singlet-triplet mixed state. A local boson
+movement is accompanied by a modulation of the spin density on the site
+resulting in the so called induced spin fluctuations. Some unconventional
+features of the induced spin fluctuations are considered including an
+appearance of the induced longitudinal ferrimagnetism with an appropriate
+contribution to the spin susceptibility, a possibility to observe and examine
+the charge fluctuations with the help of the traditional magnetic methods such
+as the magnetic inelastic neutron scattering and the spin lattice relaxation
+experiments. The suggested model, in comparison with the nearly
+antiferromagnetic Fermi-liquid model, represents new approach to the
+description of the spin system of the high-$T_c$ cuprates.",9711116v1
+2006-02-02,Lattice Distortion and Magnetism of 3d-$t_{2g}$ Perovskite Oxides,"Several puzzling aspects of interplay of the experimental lattice distortion
+and the the magnetic properties of four narrow $t_{2g}$-band perovskite oxides
+(YTiO$_3$, LaTiO$_3$, YVO$_3$, and LaVO$_3$) are clarified using results of
+first-principles electronic structure calculations. First, we derive parameters
+of the effective Hubbard-type Hamiltonian for the isolated $t_{2g}$ bands using
+newly developed downfolding method for the kinetic-energy part and a hybrid
+approach, based on the combination of the random-phase approximation and the
+constraint local-density approximation, for the screened Coulomb interaction
+part. Then, we solve the obtained Hamiltonian using a number of techniques,
+including the mean-field Hartree-Fock (HF) approximation, the second-order
+perturbation theory for the correlation energy, and a variational superexchange
+theory. Even though the crystal-field splitting is not particularly large to
+quench the orbital degrees of freedom, the crystal distortion imposes a severe
+constraint on the form of the possible orbital states, which favor the
+formation of the experimentally observed magnetic structures in YTiO$_3$,
+YVO$_$, and LaVO$_3$ even at the HF level. Beyond the HF approximation, the
+correlations effects systematically improve the agreement with the experimental
+data. Using the same type of approximations we could not reproduce the correct
+magnetic ground state of LaTiO$_3$. However, we expect that the situation may
+change by systematically improving the level of approximations for dealing with
+the correlation effects.",0602035v1
+2009-04-02,The layered iron arsenides Sr2CrO3FeAs and Ba2ScO3FeAs,"Polycrystalline samples of the layered iron arsenides Sr2CrO3FeAs and
+Ba2ScO3FeAs were synthesized by high temperature solid state reactions and
+their crystal structures determined by the X-ray powder diffraction. Their
+structures are tetragonal (P4/nmm; Sr2CrO3FeAs: a = 391.12(1) pm, c =
+1579.05(3) pm; Ba2ScO3FeAs: a = 412.66(5) pm, c = 1680.0(2) pm, Z = 2) and
+isotypic to Sr2ScO3CuS. Iron arsenide layers are sandwiched between
+perowskite-like oxide blocks and separated by ~1600 pm, which is much larger
+compared to the 1111 iron arsenide superconductors. The bond length and angles
+within the FeAs layers are adapted to the space requirements of the oxide
+blocks. Measurements of the magnetic susceptibility and electrical resistivity
+show no hint for a SDW-like anomaly in both compounds. Sr2CrO3FeAs shows
+Curie-Weiss paramagnetism above 160 K with an effective magnetic moment of
+3.83(3) muB in good agreement with the theoretical value of 3.87 muB for Cr3+.
+Antiferromagnetic ordering was detected below TN ~ 31 K. 57Fe Moessbauer
+spectra of Sr2CrO3FeAs show a single signal that broadens below the magnetic
+ordering temperature due to a small transferred hyperfine field induced by the
+magnetic ordering of the chromium atoms. 57Fe-Moessbauer spectra of Ba2ScO3FeAs
+show single signals at 298, 77, and 4.2 K which are only subject to weak
+quadrupole splitting.",0904.0479v2
+2009-09-19,"Electronic phase diagram of the layered cobalt oxide system, LixCoO2 (0.0 <= x <= 1.0)","Here we report the magnetic properties of the layered cobalt oxide system,
+LixCoO2, in the whole range of Li composition, 0 <= x <= 1. Based on
+dc-magnetic susceptibility data, combined with results of 59Co-NMR/NQR
+observations, the electronic phase diagram of LixCoO2 has been established. As
+in the related material NaxCoO2, a magnetic critical point is found to exist
+between x = 0.35 and 0.40, which separates a Pauli-paramagnetic and a
+Curie-Weiss metals. In the Pauli-paramagnetic regime (x <= 0.35), the
+antiferromagnetic spin correlations systematically increase with decreasing x.
+Nevertheless, CoO2, the x = 0 end member is a non-correlated metal in the whole
+temperature range studied. In the Curie-Weiss regime (x >= 0.40), on the other
+hand, various phase transitions are observed. For x = 0.40, a susceptibility
+hump is seen at 30 K, suggesting the onset of static AF order. A magnetic jump,
+which is likely to be triggered by charge ordering, is clearly observed at Tt =
+175 K in samples with x = 0.50 (= 1/2) and 0.67 (= 2/3), while only a tiny kink
+appears at T = 210 K in the sample with an intermediate Li composition, x =
+0.60. Thus, the phase diagram of the LixCoO2 system is complex, and the
+electronic properties are sensitively influenced by the Li content (x).",0909.3556v2
+2009-11-02,Direct Search for a Ferromagnetic Phase in a Heavily Overdoped Nonsuperconducting Copper Oxide,"The doping of charge carriers into the CuO2 planes of copper oxide Mott
+insulators causes a gradual destruction of antiferromagnetism and the emergence
+of high-temperature superconductivity. Optimal superconductivity is achieved at
+a doping concentration p beyond which further increases in doping cause a
+weakening and eventual disappearance of superconductivity. A potential
+explanation for this demise is that ferromagnetic fluctuations compete with
+superconductivity in the overdoped regime. In this case a ferromagnetic phase
+at very low temperatures is predicted to exist beyond the doping concentration
+at which superconductivity disappears. Here we report on a direct examination
+of this scenario in overdoped La2-xSrxCuO4 using the technique of muon spin
+relaxation. We detect the onset of static magnetic moments of electronic origin
+at low temperature in the heavily overdoped nonsuperconducting region. However,
+the magnetism does not exist in a commensurate long-range ordered state.
+Instead it appears as a dilute concentration of static magnetic moments. This
+finding places severe restrictions on the form of ferromagnetism that may exist
+in the overdoped regime. Although an extrinsic impurity cannot be absolutely
+ruled out as the source of the magnetism that does occur, the results presented
+here lend support to electronic band calculations that predict the occurrence
+of weak localized ferromagnetism at high doping.",0911.0407v3
+2011-03-05,"Measurement of the internal magnetic field in the correlated iridates Ca$_4$IrO$_6$, Ca$_5$Ir$_3$O$_{12}$, Sr$_3$Ir$_2$O$_7$ and Sr$_2$IrO$_4$","Oxides containing iridium ions display a range of magnetic and conducting
+properties that depend on the delicate balance between interactions and are
+controlled, at least in part, by the details of the crystal architecture. We
+have used muon-spin rotation ($\mu$SR) to study the local field in four iridium
+oxides, Ca$_4$IrO$_6$, Ca$_5$Ir$_3$O$_{12}$, Sr$_3$Ir$_2$O$_7$ and
+Sr$_2$IrO$_4$, which show contrasting behavior. Our $\mu$SR data on
+Ca$_4$IrO$_6$ and Ca$_5$Ir$_3$O$_{12}$ are consistent with conventional
+antiferromagnetism where quasistatic magnetic order develops below $T_{\rm
+N}=13.85(6)$ K and 7.84(7) K respectively. A lower internal field is observed
+for Ca$_5$Ir$_3$O$_{12}$, as compared to Ca$_4$IrO$_6$ reflecting the presence
+of both Ir$^{4+}$ and Ir$^{5+}$ ions, resulting in a more magnetically dilute
+structure. Muon precession is only observed over a restricted range of
+temperature in Sr$_3$Ir$_2$O$_7$, while the Mott insulator Sr$_2$IrO$_4$
+displays more complex behavior, with the $\mu$SR signal containing a single,
+well-resolved precession signal below $T_{\rm N}=230$\,K, which splits into two
+precession signals at low temperature following a reorientation of the spins in
+the ordered state.",1103.1036v1
+2012-07-09,Unusual magnetic phases in the strong interaction limit of two-dimensional topological band insulators in transition metal oxides,"The expected phenomenology of non-interacting topological band insulators
+(TBI) is now largely theoretically understood. However, the fate of TBIs in the
+presence of interactions remains an active area of research with novel,
+interaction-driven topological states possible, as well as new exotic magnetic
+states. In this work we study the magnetic phases of an exchange Hamiltonian
+arising in the strong interaction limit of a Hubbard model on the honeycomb
+lattice whose non-interacting limit is a two-dimensional TBI recently proposed
+for the layered heavy transition metal oxide compound, (Li,Na)$_2$IrO$_3$. By a
+combination of analytical methods and exact diagonalization studies on finite
+size clusters, we map out the magnetic phase diagram of the model. We find that
+strong spin-orbit coupling can lead to a phase transition from an
+antiferromagnetic Ne\'el state to a spiral or stripy ordered state. We also
+discuss the conditions under which a quantum spin liquid may appear in our
+model, and we compare our results with the different but related
+Kitaev-Heisenberg-$J_2$-$J_3$ model which has recently been studied in a
+similar context.",1207.2156v2
+2013-11-27,Engineered spatial inversion symmetry breaking in an oxide heterostructure built from isosymmetric room-temperature magnetically ordered components,"The oxide heterostructure [(YFeO$_3$)$_5$(LaFeO$_3$)$_5$]$_{40}$, which is
+magnetically ordered and piezoelectric at room temperature, has been
+constructed from two weak ferromagnetic AFeO$_3$ perovskites with different A
+cations using RHEED-monitored pulsed laser deposition. The polarisation arises
+through the removal of inversion centres present within the individual AFeO$_3$
+components. This symmetry reduction is a result of combining ordering on the A
+site, imposed by the periodicity of the grown structure, with appropriate
+orientations of the octahedral tilting characteristic of the perovskite units
+themselves, according to simple symmetry-controlled rules. The polarisation is
+robust against A site interdiffusion between the two layers which produces a
+sinusoidally modulated occupancy that retains the coupling of translational and
+point symmetries required to produce a polar structure. Magnetization and
+magneto-optical Kerr rotation measurements show that the heterostructure's
+magnetic structure is similar to that of the individual components. Evidence of
+the polarity was obtained from second harmonic generation and piezoelectric
+force microscopy measurements. Modeling of the piezoresponse allows extraction
+of $d_{33}$ (approximately 10 pC/N) of the heterostructure, which is in
+agreement with DFT calculations.",1311.7032v1
+2015-06-05,Ground-state selection and spin-liquid behaviour in the classical Heisenberg model on the breathing pyrochlore lattice,"Magnetic pyrochlore oxides, including the spin ice materials, have proved to
+be a rich field for the study of geometrical frustration in 3 dimensions.
+Recently, a new family of magnetic oxides has been synthesised in which the
+half of the tetrahedra in the pyrochlore lattice are inflated relative to the
+other half, making an alternating array of small and large tetrahedra. These
+""breathing pyrochlore"" materials such as LiGaCr4O8, LiInCr4O8 and Ba3Yb2Zn5O11
+provide new opportunities in the study of frustrated magnetism. Here we provide
+an analytic theory for the ground state phase diagram and spin correlations for
+the minimal model of magnetism in breathing pyrochlores: a classical nearest
+neighbour Heisenberg model with different exchange coefficients for the two
+species of tetrahedra. We find that the phase diagram comprises a Coulombic
+spin liquid phase, a conventional ferromagnetic phase and an unusual
+antiferromagnetic phase with lines of soft modes in reciprocal space,
+stabilised by an order-by-disorder mechanism. We obtain a theory of the spin
+correlations in this model using the Self Consistent Gaussian Approximation
+(SCGA) which enables us to discuss the development of correlations in breathing
+pyrochlores as a function of temperature, and we quantitatively characterise
+the thermal crossover from the limit of isolated tetrahedra to the strongly
+correlated limit of the problem. We compare the results of our analysis with
+the results of recent neutron scattering experiments on LiInCr4O8.",1506.01822v1
+2015-09-07,Emergent nanoscale superparamagnetism at oxide interfaces,"Atomically sharp oxide heterostructures exhibit a range of novel physical
+phenomena that do not occur in the parent bulk compounds. The most prominent
+example is the appearance of highly conducting and superconducting states at
+the interface between the band insulators LaAlO3 and SrTiO3. Here we report a
+new emergent phenomenon at the LaMnO3/SrTiO3 interface in which an
+antiferromagnetic insulator abruptly transforms into a magnetic state that
+exhibits unexpected nanoscale superparamagnetic dynamics. Upon increasing the
+thickness of LaMnO3 above five unit cells, our scanning nanoSQUID-on-tip
+microscopy shows spontaneous formation of isolated magnetic islands of 10 to 50
+nm diameter, which display random moment reversals by thermal activation or in
+response to an in-plane magnetic field. Our charge reconstruction model of the
+polar LaMnO3/SrTiO3 heterostructure describes the sharp emergence of
+thermodynamic phase separation leading to nucleation of metallic ferromagnetic
+islands in an insulating antiferromagnetic matrix. The model further suggests
+that the nearby superparamagnetic-ferromagnetic transition can be gate tuned,
+holding potential for applications in magnetic storage and spintronics.",1509.01895v1
+2017-01-20,"Tuning sizes, morphologies, and magnetic properties of mono- vs. multi-core iron oxide nanoparticles through control of added water in the polyol synthesis","The polyol route is a versatile and up-scalable method to produce large
+batches of iron oxide nanoparticles with well-defined structure and magnetic
+properties. Controlling parameters such as temperature and duration of
+reaction, heating profile, nature of polyol solvent or of organometallic
+precursors were reported in previous studies of literature, but none of them
+described yet the crucial role of water in the forced hydrolysis pathway, whose
+presence is mandatory for nanoparticle production. This communication
+investigates the influence of the water amount and temperature at which it is
+injected in the reflux system for either pure polyol or mixture with a
+poly(hydroxy) amine. Distinct morphologies of nanoparticles were thereby
+obtained, from ultra-ultra-small smooth spheres down to 4 nm in diameter to
+large ones up to 37 nm in diameter. Nanoflowers were also synthesized, which
+are well-defined multi-core assemblies with narrow grain size dispersity. A
+diverse and large library of samples was obtained by playing on the nature of
+solvents and amount of water traces while keeping all the other parameters
+fixed. The varied morphologies lead to magnetic nanoparticles well-fitting to
+required applications among magnetic hyperthermia and MRI contrast agent, or
+both.",1701.05858v3
+2020-04-08,Spin dynamics and a nearly continuous magnetic phase transition in an entropy-stabilized oxide antiferromagnet,"The magnetic order and the spin dynamics in the antiferromagnetic
+entropy-stabilized oxide (Mg$_{0.2}$Co$_{0.2}$Ni$_{0.2}$Cu$_{0.2}$Zn$_{0.2}$)O
+(MgO-ESO) have been studied using muon spin relaxation ($\mu$SR) and inelastic
+neutron scattering. We find that antiferromagnetic order develops gradually in
+the sample volume as it is cooled below 140 K, becoming fully ordered around
+100 K. The spin dynamics show a critical slowing down in the vicinity of the
+transition, and the magnetic order parameter grows continuously in the ordered
+state. These results indicate that the antiferromagnetic transition is
+continuous but proceeds with a Gaussian distribution of ordering temperatures.
+The magnetic contribution to the specific heat determined from inelastic
+neutron scattering likewise shows a broad feature centered around 120 K.
+High-resolution inelastic neutron scattering further reveals an initially
+gapped spectrum at low temperature which sees an increase in a quasielastic
+contribution upon heating until the ordering temperature.",2004.04218v2
+2019-02-21,Effects of the removal of Ta capping layer on the magnetization dynamics of Permalloy thin films,"We have investigated the spin wave dynamics of Permalloy (Py) thin films with
+and without a Ta capping layer for varying Py thickness (15 nm, 20 nm and 30
+nm) using all optical time-resolved magneto-optical Kerr effect measurements.
+XPS measurements confirm the oxidation of the originally-prepared samples and
+also that the removal of the Ta capping layer is achievable by a few sputtering
+cycles. The magnetic field strength dependencies of the spin wave modes with
+the variation of the Py film thickness for the samples are studied. We observe
+that the presence of the Ta capping layer reduces the precessional frequencies
+of the samples while the samples without a Ta capping layer enhance the role of
+Py thickness. We also observe that the decay time of spin waves is highly
+dependent on the top layer of the samples. The decay time increases with
+increasing Py thicknesses for Ta/Py/Ta samples implying that the enhancement of
+decay time is caused by the Ta/Py/Ta interfaces. Whereas, for Ta/Py samples the
+decay time decreases with increasing Py thickness. The results of this work
+extend the knowledge on the magnetization dynamics of Py thin films giving
+information on how to resume and even enhance the spin mobility after a
+deleterious oxidation process. This can open new scenarios on the building
+process and on the maintenance of fast magnetic switching devices.",1902.07832v1
+2019-04-19,Magnetization density distribution of Sr$_2$IrO$_4$: Deviation from a local $j_\text{eff}=1/2$ picture,"$5d$ iridium oxides are of huge interest due to the potential for new quantum
+states driven by strong spin-orbit coupling. The strontium iridate
+Sr$_2$IrO$_4$ is particularly in the spotlight because of the so-called
+$j_\text{eff}=1/2$ state consisting of a quantum superposition of the three
+local $t_{2g}$ orbitals with -- in its most simple version -- nearly equal
+population, which stabilizes an unconventional Mott insulating state. Here, we
+report an anisotropic and aspherical magnetization density distribution
+measured by polarized neutron diffraction in a magnetic field up to 5~T at 4~K,
+which strongly deviates from a local \jeffHalf picture even when
+distortion-induced deviations from the equal weights of the orbital populations
+are taken into account. Once reconstructed by the maximum entropy method and
+multipole expansion model refinement, the magnetization density shows
+cross-shaped positive four lobes along the crystallographic tetragonal axes
+with a large spatial extent, showing that the $xy$ orbital contribution is
+dominant. The analogy to the superconducting copper oxide systems might then be
+weaker than commonly thought.",1904.09139v4
+2020-05-19,Controlling the electrical and magnetic ground states by doping in the complete phase diagram of titanate Eu1-xLaxTiO3 thin films,"EuTiO3, a band insulator, and LaTiO3, a Mott insulator, are both
+antiferromagnetic with transition temperatures ~ 5.5 K and ~ 160 K,
+respectively. Here, we report the synthesis of Eu1-xLaxTiO3 thin films with x =
+0 to 1 by oxide molecular beam epitaxy. The films in the full range have high
+crystalline quality and show no phase segregation, allowing us carry out
+transport measurements to study their electrical and magnetic properties. From
+x = 0.03 to 0.95, Eu1-xLaxTiO3 films show conduction by electrons as charge
+carriers, with differences in carrier densities and mobilities, contrary to the
+insulating nature of pure EuTiO3 and LaTiO3. Following a rich phase diagram,
+the magnetic ground states of the films vary with increasing La-doping level,
+changing Eu1-xLaxTiO3 from an antiferromagnetic insulator to an
+antiferromagnetic metal, a ferromagnetic metal, a paramagnetic metal, and back
+to an antiferromagnetic insulator. These emergent properties reflect the
+evolutions of the band structure, mainly at the Ti t2g bands near the Fermi
+level, when Eu2+ are gradually replaced by La3+. This work sheds light on this
+method for designing the electrical and magnetic properties in
+strongly-correlated oxides and completes the phase diagram of the titanate
+Eu1-xLaxTiO3.",2005.09581v1
+2020-05-29,Large magnetoelectric coupling in multiferroic oxide heterostructures assembled via epitaxial lift-off,"The strain dependent functional properties of epitaxial transition metal
+oxide films can be significantly modified via substrate selection. However,
+large lattice mismatches preclude dislocation-free epitaxial growth on
+ferroelectric substrates, whose strain states are modified by applied electric
+fields. Here we overcome this mismatch problem by depositing an epitaxial film
+of ferromagnetic La0.7Sr0.3MnO3 on a single crystal substrate of well lattice
+matched SrTiO3 via a film of SrRuO3 that we subsequently dissolved, permitting
+the transfer of unstrained La0.7Sr0.3MnO3 to a ferroelectric substrate of
+0.68Pb(Mg1/3Nb2/3)O3 0.32PbTiO3 in a different crystallographic orientation.
+Ferroelectric domain switching, and a concomitant ferroelectric phase
+transition, produced large non volatile changes of magnetization that were
+mediated by magnetic domain rotations at locations defined by the
+microstructure - as revealed via high resolution vector maps of magnetization
+constructed from photoemission electron microscopy data, with contrast from
+x-ray magnetic circular dichroism. In future, our method may be exploited to
+control functional properties in dislocation free epitaxial films of any
+composition.",2006.00034v2
+2021-03-16,Emergent Magnetic Phenomenon with Unconventional Structure in Epitaxial Manganate Thin Films,"A variety of emergent phenomena has been enabled by interface engineering in
+the complex oxides heterostructures. While extensive attention has been
+attracted to LaMnO3 (LMO) thin films for observing the control of
+functionalities at its interface with substrate, the nature of the magnetic
+phases in the thin film is, however,controversial. Here, it is reported that
+the ferromagnetism in 2 and 5 unit cells thick LMO films epitaxially deposited
+(001)-SrTiO3 substrates ferromagnetic/ferromagnetic coupling in 8 and
+10-unit-cell ones, and a striking ferromagnetic/antiferromagnetic pinning
+effect with apparent positive exchange bias in 15 and 20-unit-cell ones are
+observed. This novel phenomenon in both 15 and 20-unit-cell films indicates a
+coexistence of three magnetic orderings in a single LMO film.The
+high-resolution scanning transmission electron microscopy suggests a P21/n to
+Pbnm symmetry transition from interface to surface, with the spatial
+stratification of MnO6 octahedral morphology, corresponding to different
+magnetic orderings. These results should shed some new lights on manipulating
+the functionality of oxides by interface engineering.",2103.09133v1
+2021-08-10,Site-selective magnetic moment collapse in compressed Fe5O6,"Iron oxide is one of the most important components in Earth's mantle. Recent
+discovery of the stable presence of Fe5O6 at Earth's mantle environment
+stimulates significant interests in the understanding of this new category of
+iron oxides. In this paper, we report the electronic structure and magnetic
+properties of Fe5O6 calculated by the density functional theory plus dynamic
+mean field theory (DFT+DMFT) approach. Our calculations indicate that Fe5O6 is
+a conductor at the ambient pressure with dominant Fe-3d density of states at
+the Fermi level. The magnetic moments of iron atoms at three non-equivalent
+crystallographic sites in Fe5O6 collapse at significantly different rate under
+pressure. Such site-selective collapse of magnetic moments originates from the
+shifting of energy levels and the consequent charge transfer among the Fe-3d
+orbits when Fe5O6 is being compressed. Our simulations suggest that there could
+be high conductivity and volume contraction in Fe5O6 at high pressure, which
+may induce anomalous features in seismic velocity, energy exchange, and mass
+distribution at the deep interior of Earth.",2108.04473v1
+2021-12-22,Low temperature magnetic and dielectric properties correlation in Fe-doped copper (ii) oxide ceramics for potential device application,"The bulk samples of CuO and Fe-doped CuO were synthesized by ceramics
+methods. Structural and compositional analyses were performed by using X-ray
+diffraction, SEM, and EDAX. Through this manuscript, we are going to report the
+effect of trivalent iron doping (Fe$^{3+}$) in copper (II) oxide
+(Cu$_{0.95}$Fe$_{0.05}$O) bulk samples on magnetic and dielectric behavior. The
+paramagnetic phase has been established in CuO as a result of Fe$^{3+}$ doping.
+The strong correlation between magnetic and dielectric properties indicated
+spin-polaron interaction at the transition temperature. Bulk CuO and also
+Cu$_{0.95}$Fe$_{0.05}$O exhibit the multiferroic phase in a narrow temperature
+range (190 K to 230 K). Two transitions happened from a
+paramagnetic-paraelectric phase to incommensurate or asymmetrical
+antiferromagnetic (AF) and ferroelectric state near highest Neel temperature
+(TN1) ~230 K and another second phase transition, the order of AF phase
+transformed to commensurate AF phase and ferroelectricity disappeared at around
+the Neel temperature (TN2) ~210 K in all samples. This Cu$_{0.95}$Fe$_{0.05}$O
+would show its potential in the spintronic application for a high dielectric
+constant with low loss and high magnetic susceptibility.",2112.11874v1
+2022-10-25,Engineered Kondo screening and nonzero Berry phase in SrTiO3/LaTiO3/SrTiO3 heterostructures,"Controlling the interplay between localized spins and itinerant electrons at
+the oxide interfaces can lead to exotic magnetic states. Here we devise
+SrTiO3/LaTiO3/SrTiO3 heterostructures with varied thickness of the LaTiO3 layer
+(n monolayers) to investigate the magnetic interactions in the two-dimensional
+electron gas system. The heterostructures exhibit significant Kondo effect when
+the LaTiO3 layer is rather thin (n = 2, 10), manifesting the strong interaction
+between the itinerant electrons and the localized magnetic moments at the
+interfaces, while the Kondo effect is greatly inhibited when n = 20. Notably,
+distinct Shubnikov-de Haas oscillations are observed and a nonzero Berry phase
+of {\pi} is extracted when the LaTiO3 layer is rather thin (n = 2, 10), which
+is absent in the heterostructure with thicker LaTiO3 layer (n = 20). The
+observed phenomena are consistently interpreted as a result of sub-band
+splitting and symmetry breaking due to the interplay between the interfacial
+Rashba spin-orbit coupling and the magnetic orderings in the heterostructures.
+Our findings provide a route for exploring and manipulating nontrivial
+electronic band structures at complex oxide interfaces.",2210.13951v1
+2023-07-15,"Controlling electronic, magnetic, thermal, and optical properties of boron-nitrogen codoped strontium oxide monolayer: Activation of optical transitions in the VL region","The electronic, thermal, magnetic and optical properties of BN-codoped
+strontium oxide (SrO) monolayers are studied taking into account the
+interaction effects between the B and the N dopant atoms. The indirect band gap
+of a pure two dimensional SrO is modified to a narrow direct band gap by tuning
+the B-N attractive interaction. The B or N separately doped SrO leads to a
+metallic behavior, while a BN-codoped SrO has a semiconductor character. The
+strong B-N attractive interaction changes a non-magnetic SrO to a magnetic
+system and reduces its heat capacity. An ab initio molecular dynamics, AIMD,
+calculations are also utilized to check the thermodynamic stability of the pure
+and BN-codoped SrO monolayers. The band gap reduction of SrO increases the
+optical conductivity shifting the most intense peak from the Deep-UV to the
+visible light region. The red shifted optical conductivity emerges due to the
+B-N attractive interaction. In addition, both iso- and anisotropic characters
+are seen in the optical properties depending on the strength of the B-N
+attractive interaction. It can thus be confirmed that the interaction effects
+of the BN-codopants can be used to control the properties of SrO monolayers for
+thermo- and opto-electronic devices.",2307.09173v1
+2023-12-10,Stability and Character of Zero Field Skyrmionic States in Hybrid Magnetic Multilayer Nanodots,"Ambient magnetic skyrmions stabilized in multilayer nanostructures are of
+immense interest due to their relevance to magnetic tunnel junction (MTJ)
+devices for memory and unconventional computing applications. However, existing
+skyrmionic nanostructures built using conventional metallic or oxide multilayer
+nanodots are unable to concurrently fulfill the requirements of nanoscale
+skyrmion stability and feasibility of all-electrical readout and manipulation.
+Here, we develop a few-repeat hybrid multilayer platform consisting of metallic
+[Pt/CoB/Ir]3 and oxide [Pt/CoB/MgO] components that are coupled to evolve
+together as a single, composite stack. Zero-field (ZF) skyrmions with sizes as
+small as 50 nm are stabilized in the hybrid multilayer nanodots, which are
+smoothly modulated by up to 2.5x by varying CoB thickness and dot sizes.
+Meanwhile, skyrmion multiplets are also stabilized by small bias fields.
+Crucially, we observe higher order 'target' skyrmions with varying
+magnetization rotations in moderately-sized, low anisotropy nanodots. These
+results provide a viable route to realize long-sought skyrmionic MTJ devices
+and new possibilities for multi-state skyrmionic device concepts.",2312.05801v1
+2016-06-16,"Magnetic Properties from the Viewpoints of Electronic Hamiltonian: Spin Exchange Parameters, Spin Orientation and Spin-Half Misconception","In this chapter we review the quantitative and qualitative aspects of
+describing the properties of magnetic solids on the basis of electronic
+Hamiltonian. We show that a spin Hamiltonian approach becomes consistent with
+an electronic Hamiltonian approach if the spin lattice and its associated spin
+exchange parameters, to be used for the spin Hamiltonian, are determined by the
+energy-mapping analysis based on DFT calculations. The preferred spin
+orientation (i.e., the magnetic anisotropy) of a magnetic ion is not predicted
+by a spin Hamiltonian because it does not include the orbital degree of freedom
+explicitly. In contrast, the magnetic anisotropy is readily predicted by
+electronic structure theories employing both orbital and spin degrees of
+freedom, if one takes into consideration the spin-orbit coupling (SOC). It was
+shown that the preferred spin orientation of a magnetic ion can be predicted
+and understood in terms of the HOMO-LUMO interactions of the magnetic ion by
+taking SOC as perturbation. A spin Hamiltonian gives rise to the spin-half
+misconception, namely, the blind belief that spin-half magnetic ions do not
+possess magnetic anisotropy that arise from SOC. This misconception is a direct
+consequence from the limitedness of a spin Hamiltonian that it lacks the
+orbital degree of freedom. We show that the magnetic properties of 5d ion
+oxides are better explained by the LS-coupling than by the jj-coupling scheme
+of SOC, that the spin-orbital entanglement of 5d ions is not as strong as has
+been assumed.",1606.05220v1
+2016-07-14,Reading and Writing Single-Atom Magnets,"The highest-density magnetic storage media will code data in single-atom
+bits. To date, the smallest individually addressable bistable magnetic bits on
+surfaces consist of 5-12 atoms. Long magnetic relaxation times were
+demonstrated in molecular magnets containing one lanthanide atom, and recently
+in ensembles of single holmium (Ho) atoms supported on magnesium oxide (MgO).
+Those experiments indicated the possibility for data storage at the fundamental
+limit, but it remained unclear how to access the individual magnetic centers.
+Here we demonstrate the reading and writing of individual Ho atoms on MgO, and
+show that they independently retain their magnetic information over many hours.
+We read the Ho states by tunnel magnetoresistance and write with current pulses
+using a scanning tunneling microscope. The magnetic origin of the long-lived
+states is confirmed by single-atom electron paramagnetic resonance (EPR) on a
+nearby Fe sensor atom, which shows that Ho has a large out-of-plane moment of
+$(10.1 \pm 0.1)$ $\mu_{\rm B}$ on this surface. In order to demonstrate
+independent reading and writing, we built an atomic scale structure with two Ho
+bits to which we write the four possible states and which we read out remotely
+by EPR. The high magnetic stability combined with electrical reading and
+writing shows that single-atom magnetic memory is possible.",1607.03977v1
+2016-09-13,Enhancing interfacial magnetization with a ferroelectric,"Ferroelectric control of interfacial magnetism has attracted much attention.
+However, the coupling of these two functionalities has not been understood well
+at the atomic scale. The lack of scientific progress is mainly due to the
+limited characterization methods by which the interface's magnetic properties
+can be probed at an atomic level. Here, we use polarized neutron reflectometry
+(PNR) to probe the evolution of the magnetic moment at interfaces in
+ferroelectric/strongly correlated oxide [PbZr0.2Ti0.8O3/La0.8Sr0.2MnO3
+(PZT/LSMO)] heterostructures. We find that there is always suppressed
+magnetization at the surface and interface of LSMO and such magnetic
+deterioration can be strongly improved by interfacing with a strongly polar PZT
+film. The magnetoelectric coupling of magnetism and ferroelectric polarization
+occurs within a couple of nanometers of the interface as demonstrated by the
+enhanced interfacial magnetization beyond the bulk value by 5% depending on the
+polarization of PZT. The latter value is 70% higher than the surface
+magnetization of a LSMO film without interfacing with a ferroelectric layer.
+These compelling results not only probe the presence of nanoscale magnetic
+suppression and its control by ferroelectrics, but also emphasize the
+importance of utilizing probing techniques that can distinguish between bulk
+and interfacial phenomena.",1609.03983v1
+2018-04-02,Collective Coordinate Descriptions of Magnetic Domain Wall Motion in Perpendicularly Magnetized Nanostructures under the Application of In-plane Fields,"Manipulation of magnetic domain walls can be used to improve the capabilities
+of the next generation of memory and sensing devices. Materials of recent
+interest for such devices include heterostructures of ultrathin ferromagnets
+sandwiched between a heavy metal and an oxide, where spin-orbit coupling and
+broken inversion symmetry give rise to the Dzyaloshinskii-Moriya interaction
+(DMI), stabilizing chiral domain walls. The efficiency of the motion of these
+chiral domain walls may be controlled using in-plane magnetic fields. This
+property has been used for measurement of DMI strength. While micromagnetic
+simulations are able to accurately predict domain wall motion under in-plane
+fields in these materials, collective coordinate models such as the $q-\phi$
+and $q-\phi-\chi$ models fail to reproduce the micromagnetic results. In this
+theoretical work, we present a set of extended collective coordinate models
+including canting in the domains, which better reproduce micromagnetic results,
+and helps us better understand the effect of in-plane fields on magnetic domain
+walls. These models are used in conjunction with micromagnetic simulations to
+identify critical points observed in the motion of the domain walls driven by
+out-of-plane magnetic fields, and electric current under magnetic in-plane
+fields. Our new models and results help in the development of future domain
+wall based devices based on perpendicularly magnetized materials.",1804.00569v3
+2019-01-05,Investigating the Effect of Magnetic Dipole-Dipole Interaction on Magnetic Particle Spectroscopy (MPS): Implications for Magnetic Nanoparticle-based Bioassays and Magnetic Particle Imaging (MPI),"Superparamagnetic iron oxide nanoparticles (SPIONs), with comparable size to
+biomolecules (such as proteins, nucleic acids, etc.) and unique magnetic
+properties, good biocompatibility, low toxicity, potent catalytic behavior, are
+promising candidates for many biomedical applications. There is one property
+present in most SPION systems, yet it has not been fully exploited, which is
+the dipole-dipole interaction (also called dipolar interaction) between the
+SPIONs. It is known that the magnetic dynamics of an ensemble of SPIONs are
+substantially influenced by the dipolar interactions. However, the exact way it
+affects the performance of magnetic particle-based bioassays and magnetic
+particle imaging (MPI) is still an open question. The purpose of this paper is
+to give a partial answer to this question. This is accomplished by numerical
+simulations on the dipolar interactions between two nearby SPIONs and
+experimental measurements on an ensemble of SPIONs using our lab-based magnetic
+particle spectroscopy (MPS) system. Our results show that even moderate changes
+in the SPION concentration may have substantial effects on the magnetic
+dynamics of the SPION system and the harmonic signal magnitudes can be
+increased or decreased by 60%, depending on the values of MPS system
+parameters.",1901.01355v1
+2019-08-29,Tuning Single-Atom Electron Spin Resonance in a Vector-Magnetic Field,"Spin resonance of single spin centers bears great potential for chemical
+structure analysis, quantum sensing and quantum coherent manipulation.
+Essential for these experiments is the presence of a two-level spin system
+whose energy splitting can be chosen by applying a magnetic field. In recent
+years, a combination of electron spin resonance (ESR) and scanning tunneling
+microscopy (STM) has been demonstrated as a technique to detect magnetic
+properties of single atoms on surfaces and to achieve sub-${\mu}$eV energy
+resolution. Nevertheless, up to now the role of the required magnetic fields
+has not been elucidated. Here, we perform single-atom ESR on individual Fe
+atoms adsorbed on magnesium oxide (MgO), using a 2D vector magnetic field as
+well as the local field of the magnetic STM tip in a commercially available
+STM. We show how the ESR amplitude can be greatly improved by optimizing the
+magnetic fields, revealing in particular an enhanced signal at large in-plane
+magnetic fields. Moreover, we demonstrate that the stray field from the
+magnetic STM tip is a versatile tool. We use it here to drive the electron spin
+more efficiently and to perform ESR measurements at constant frequency by
+employing tip-field sweeps. Lastly, we show that it is possible to perform ESR
+using only the tip field, under zero external magnetic field, which promises to
+make this technique available in many existing STM systems.",1908.11061v1
+2021-03-24,Structural and Magnetic Transitions in the Planar Antiferromagnet Ba$_4$Ir$_3$O$_{10}$,"We report the structural and magnetic ground state properties of the
+monoclinic compound barium iridium oxide Ba$_4$Ir$_3$O$_{10}$ using a
+combination of resonant x-ray scattering, magnetometry, and thermodynamic
+techniques. Magnetic susceptibility exhibits a pronounced antiferromagnetic
+transition at $T_{\text{N}}$ $\approx$ 25K, a weaker anomaly at $T_{\text{S}}$
+$\approx$ 142K, and strong magnetic anisotropy at all temperatures. Resonant
+elastic x-ray scattering experiments reveal a second order structural phase
+transition at $T_{\text{S}}$ and a magnetic transition at $T_{\text{N}}$. Both
+structural and magnetic superlattice peaks are observed at $L$ = half integer
+values. The magnetization anomaly at $T_{\text{S}}$ implies the presence of
+magneto-elastic coupling, which conceivably facilitates the symmetry lowering.
+Mean field critical scattering is observed above $T_{\text{S}}$. The magnetic
+structure of the antiferromagnetic ground state is discussed based on the
+measured magnetic superlattice peak intensity. Our study not only presents
+essential information for understanding the intertwined structural and magnetic
+properties in Ba$_4$Ir$_3$O$_{10}$, but also highlights the necessary
+ingredients for exploring novel ground states with octahedra trimers.",2103.12979v1
+2012-10-30,Electronic structure of TiO2 thin films and LaAlO3-SrTiO3 heterostructures: the role of titanium 3d1 states in magnetic and transport properties,"In this Thesis, a study of the electronic structure of two Ti-based oxide
+systems, TiO2 thin films and the ultra-thin LaAlO3-SrTiO3 (LAO-STO)
+heterojunctions, is given. A weak room-temperature ferromagnetism (FM) has been
+detected in slightly reduced TiO2 thin film and in other oxides; as these
+materials are insulating closed-shell systems, this phenomenon has been
+classified as ""d0 magnetism"". Since this magnetism could be related to the
+growth process and to the presence of defects (oxygen vacancies, VO), an
+analysis of Ti electronic states (especially of Ti3+ energy levels) is
+mandatory. The first part of this work is devoted to the magnetic
+characterization of a set of TiO2 and N-doped TiO2 samples, together with the
+analysis of Ti 3d-related states carried out with X-ray photoemission (XPS) and
+resonant photoemission (ResPES). The hypothesis of clustered VO as the source
+of FM is then discussed in the light of the experimental and theoretical
+results. Another interesting oxide system in which the stoichiometry of Ti ions
+play a fundamental role is the LAO-STO interface. In fact, while LAO and STO
+separately are two band insulators, the interface created by growing LAO on the
+top of STO (001) has found to become metallic, hosting a 2D electron gas. The
+second part of this Thesis is devoted to the study of conductive and insulating
+LAO-STO interfaces, carried out by XPS, X-ray absorption (XAS) and with ResPES.
+The sample stoichiometry is evaluated through a comparison with LAO and STO
+single crystals. A resonance enhancement of the conductive Ti states,
+associated to Ti3+ ions, is reported and compared to theoretical calculations.
+On the basis of these results, the origin of metallic states in ultra-thin
+LAO-STO interfaces is properly addressed. In addition, a characterization of
+the structural disorder at the interface is shown, carried out with
+angle-resolved XPS.",1210.8000v1
+2019-11-29,"Role of Ni substitution on structural, magnetic and electronic properties of epitaxial CoCr2O4 spinel thin films","Cubic spinel CoCr2O4 has attained recent attention due to its multiferroic
+properties. However, the Co site substitution effect on the structural and
+magnetic properties has rarely been studied in thin film form. In this work,
+the structural and magnetic properties of Co1-xNixCr2O4 (x = 0, 0.5) epitaxial
+thin films deposited on MgAl2O4 (100) and MgO (100) substrates to manipulate
+the nature of strain in the films using pulsed laser deposition (PLD) technique
+are presented. The epitaxial nature of the films was confirmed through X-ray
+diffraction (XRD) and Rutherford backscattering spectrometry (RBS)
+measurements. Raman measurements revealed a disappearance of characteristic A1g
+and F2g modes of the CoCr2O4 with increase in the Ni content. Atomic force
+microscopy (AFM) studies show a modification of the surface morphology upon Ni
+substitution. Magnetic measurements disclose that the ferrimagnetic Curie
+temperature (Tc) of the CoCr2O4 in thin film grown on MgAl2O4 (100) and MgO
+(100) substrates were found to be 100.6 +/- 0.5 K and 93.8 +/- 0.2 K,
+respectively. With Ni substitution the transition temperatures significantly
+get enhanced from that of CoCr2O4. X-ray photoelectron spectroscopy (XPS)
+suggests Cr3+ oxidation states in the films, while Co ions are present in a
+mixed Co2+/Co3+ oxidation state. The substitution of Ni at Co site
+significantly modifies the line shape of the core level as well as the valence
+band. Ni ions are also found to be in a mixed 2+/3+ oxidation state. O 1s core
+level display asymmetry related to possible defects like oxygen vacancies in
+the films.",1912.00051v1
+2020-03-12,Magnetism and Ion Diffusion in Honeycomb Layered Oxide K$_2$Ni$_2$TeO$_6$: First Time Study by Muon Spin Rotation & Neutron Scattering,"In the quest of finding novel and efficient batteries, a great interest has
+raised in K-based honeycomb layer oxide materials both for their fundamental
+properties and potential applications. A key issue in the realization of
+efficient batteries based on such compounds, is to understand the K-ion
+diffusion mechanism. However, investigation of potassium-ion (K$^+$) dynamics
+in materials using magneto-spin properties has so far been challenging, due to
+its inherently weak nuclear magnetic moment, in contrast to other alkali ions
+such as lithium and sodium. Spin-polarised muons, having a high gyromagnetic
+ratio, make the muon spin rotation and relaxation ($\mu$+SR) technique ideal
+for probing ions dynamics in weak magneto-spin moment materials. Here we report
+the magnetic properties and K+ dynamics in honeycomb layered oxide material of
+the K$_2$Ni$_2$TeO$_6$ using $\mu$+SR measurements. Our low-temperature
+$\mu$+SR results together with, with complementary magnetic susceptibility,
+find an antiferromagnetic transition at 26 K. Further $\mu$+SR studies
+performed at higher temperatures reveal that potassium ions (K$^+$) become
+mobile above 250 K and the activation energy for the diffusion process is Ea =
+121(13) meV. This is the first time that K+ dynamics in potassium-based battery
+materials has been measured using $\mu$+SR. Finally our results also indicate
+an interesting possibility that K-ion self diffusion occurs predominantly at
+the surface of the powder particles. This opens future possibilities for
+improving ion diffusion and device performance using nano-structuring.",2003.05805v2
+2004-04-30,"Orbital and spin interplay in spin-gap formation in pyroxene titanium oxides ATiSi2O6 (A=Na, Li)","Interplay between orbital and spin degrees of freedom is theoretically
+studied for the phase transition to the spin-singlet state with lattice
+dimerization in pyroxene titanium oxides ATiSi2O6 (A=Na, Li). For the quasi
+one-dimensional spin-1/2 systems, we derive an effective spin-orbital-lattice
+coupled model in the strong correlation limit with explicitly taking account of
+the t_2g orbital degeneracy, and investigate the model by numerical simulation
+as well as the mean-field analysis. We find a nontrivial feedback effect
+between orbital and spin degrees of freedom; as temperature decreases,
+development of antiferromagnetic spin correlations changes the sign of orbital
+correlations from antiferro to ferro type, and finally the ferro-type orbital
+correlations induce the dimerization and the spin-singlet formation. As a
+result of this interplay, the system undergoes a finite-temperature transition
+to the spin-dimer and orbital-ferro ordered phase concomitant with the
+Jahn-Teller lattice distortion. The numerical results for the magnetic
+susceptibility show a deviation from the Curie-Weiss behavior, and well
+reproduce the experimental data. The results reveal that the Jahn-Teller energy
+scale is considerably small and the orbital and spin exchange interactions play
+a decisive role in the pyroxene titanium oxides.",0404730v2
+2006-03-16,Low energy physical properties of high-Tc superconducting Cu oxides: A comparison between the resonating valence bond and experiments,"In a recent review by Anderson and coworkers\cite{Vanilla}, it was pointed
+out that an early resonating valence bond (RVB) theory is able to explain a
+number of unusual properties of high temperature superconducting (SC)
+Cu-oxides. Here we extend previous calculations \cite{anderson87,FC
+Zhang,Randeria} to study more systematically low energy physical properties of
+the plain vanilla d-wave RVB state, and to compare results with the available
+experiments. We use a renormalized mean field theory combined with variational
+Monte Carlo and power Lanczos methods to study the RVB state of an extended
+$t-J$ model in a square lattice with parameters suitable for the hole doped
+Cu-oxides. The physical observable quantities we study include the specific
+heat, the linear residual thermal conductivity, the in-plane magnetic
+penetration depth, the quasiparticle energy at the antinode $(\pi, 0)$, the
+superconducting energy gap, the quasiparticle spectra and the Drude weight. The
+traits of nodes (including $k_{F}$, the Fermi velocity $v_{F}$ and the velocity
+along Fermi surface $v_{2}$), as well as the SC order parameter are also
+studied. Comparisons of the theory and the experiments in cuprates show an
+overall qualitative agreement, especially on their doping dependences.",0603423v5
+2011-12-21,Anisotropic conductance at improper ferroelectric domain walls,"Transition metal oxides hold great potential for the development of new
+device paradigms because of the field-tunable functionalities driven by their
+strong electronic correlations, combined with their earth abundance and
+environmental friendliness. Recently, the interfaces between transition-metal
+oxides have revealed striking phenomena such as insulator-metal transitions,
+magnetism, magnetoresistance, and superconductivity. Such oxide interfaces are
+usually produced by sophisticated layer-by-layer growth techniques, which can
+yield high quality, epitaxial interfaces with almost monolayer control of
+atomic positions. The resulting interfaces, however, are fixed in space by the
+arrangement of the atoms. Here we demonstrate a route to overcoming this
+geometric limitation. We show that the electrical conductance at the
+interfacial ferroelectric domain walls in hexagonal ErMnO3 is a continuous
+function of the domain wall orientation, with a range of an order of magnitude.
+We explain the observed behaviour using first-principles density functional and
+phenomenological theories, and relate it to the unexpected stability of
+head-to-head and tail-to-tail domain walls in ErMnO3 and related hexagonal
+manganites. Since the domain wall orientation in ferroelectrics is tunable
+using modest external electric fields, our finding opens a degree of freedom
+that is not accessible to spatially fixed interfaces.",1112.5194v1
+2012-06-06,Irreversibility and time relaxation in electrostatic doping of oxide interfaces,"Two-dimensional electron gas (2DEG) confined in quantum wells at insulating
+oxide interfaces have attracted much attention as their electronic properties
+display a rich physics with various electronics orders such as
+superconductivity and magnetism. A particularly exciting features of these
+hetero-structures lies in the possibility to control their electronic
+properties by electrostatic gating, opening up new opportunities for the
+development of oxide based electronics. However, unexplained gating hysteresis
+and time relaxation of the 2DEG resistivity have been reported in some bias
+range, raising the question of the precise role of the gate voltage. Here we
+show that in LaTiO3/SrTiO3 and LaAlO3/SrTiO3 heterostructures, above a filling
+threshold, electrons irreversibly escape out of the well. This mechanism, which
+is directly responsible for the hysteresis and time relaxation, can be entirely
+described by a simple analytical model derived in this letter. Our results
+highlight the crucial role of the gate voltage both on the shape and the
+filling of the quantum well. They also demonstrate that it is possible to
+achieve a low-carrier density regime in a semiconductor limit, whereas the
+high-carrier density regime is intrinsically limited.",1206.1198v1
+2012-08-30,Unexpected Anisotropic Two Dimensional Electron Gas at the LaAlO3/SrTiO3 (110) Interface,"The observation of a two dimensional electron gas (2DEG) (1, 2),
+superconductivity (3, 4), magnetic effects (5) and electronic phase separation
+(6-8) at the interfaces of insulating oxides, especially LaAlO3/SrTiO3, has
+further enhanced the potential of complex oxides for novel electronics. The
+occurrence of the 2DEG is strongly believed to be driven by the polarization
+discontinuity (9) at the interface between the two oxides. In this scenario,
+the crystal orientation plays an important role and no conductivity would be
+expected for e.g., the interface between LaAlO3 and (110)-oriented SrTiO3,
+which should not have a polarization discontinuity (10, 11). Here, we report
+the observation of unexpected conductivity at the LaAlO3/SrTiO3 interface
+prepared on (110)-oriented SrTiO3. The conductivity was further found to be
+strongly anisotropic, with the ratio of the conductance along the different
+directions parallel to the substrate surface showing a remarkable dependence on
+the oxygen pressure during deposition. The conductance and its anisotropy are
+discussed based on the atomic structure at the interface, as revealed by
+Scanning Transmission Electron Microscopy (STEM) and further supported by
+density functional theory (DFT) calculations.",1208.6135v1
+2012-10-05,"Rapid Size-Controlled Synthesis of Dextran-Coated, 64Cu-Doped Iron Oxide Nanoparticles","Research into developing dual modality probes enabled for magnetic resonance
+imaging (MRI) and positron emission tomography (PET) has been on the rise
+recently due to the potential to combine the high resolution of MRI and the
+high sensitivity of PET. Current synthesis techniques for developing multimodal
+probes is largely hindered in part by prolonged reaction times during
+radioisotope incorporation - leading to a weakening of the radioactivity. Along
+with a time-efficient synthesis, the resulting products must fit within a
+critical size range (between 20-100nm) to increase blood retention time. In
+this work, we describe a novel, rapid, microwave-based synthesis technique to
+grow dextran-coated iron oxide nanoparticles doped with copper (DIO/Cu).
+Traditional methods for coprecipitation of dextran-coated iron oxide
+nanoparticles require refluxing for 2 hours and result in approximately 50 nm
+diameter particles. We demonstrate that microwave synthesis can produce 50 nm
+nanoparticles with 5 minutes of heating. We discuss the various parameters used
+in the microwave synthesis protocol to vary the size distribution of DIO/Cu,
+and demonstrate the successful incorporation of 64Cu into these particles with
+the aim of future use for dual-mode MR/PET imaging.",1210.1823v1
+2015-05-04,Vacancy Formation and Oxidation Characteristics of Single Layer TiS3,"The structural, electronic, and magnetic properties of pristine, defective,
+and oxidized monolayer TiS3 are investigated using first-principles
+calculations in the framework of density functional theory. We found that a
+single layer of TiS3 is a direct band gap semiconductor, and the bonding nature
+of the crystal is fundamentally different from other transition metal
+chalcogenides. The negatively charged surfaces of single layer TiS3 makes this
+crystal a promising material for lubrication applications. The formation
+energies of possible vacancies, i.e. S, Ti, TiS, and double S, are investigated
+via total energy optimization calculations. We found that the formation of a
+single S vacancy was the most likely one among the considered vacancy types.
+While a single S vacancy results in a nonmagnetic, semiconducting character
+with an enhanced band gap, other vacancy types induce metallic behavior with
+spin polarization of 0.3-0.8 {\mu}B. The reactivity of pristine and defective
+TiS3 crystals against oxidation was investigated using conjugate gradient
+calculations where we considered the interaction with atomic O, O2, and O3.
+While O2 has the lowest binding energy with 0.05-0.07 eV, O3 forms strong bonds
+stable even at moderate temperatures. The strong interaction (3.9-4.0 eV)
+between atomic O and TiS3 results in dissociative adsorption of some
+O-containing molecules. In addition, the presence of S-vacancies enhances the
+reactivity of the surface with atomic O, whereas it had a negative effect on
+the reactivity with O2 and O3 molecules.",1505.00827v1
+2015-10-15,"Mott transitions and Novel Orders in Multi-Orbital Models: The Relevance of Structural ""Double Exchange""","In real transition-metal oxides, the so-called GdFeO3 octahedral tilt is long
+known to be a relevant control parameter influencing the range of orbital and
+magnetic ordered states found across families of cubic perovskite families.
+Their precise role in the interplay between itinerance and localisation, long
+known to underpin Mottness in d-band oxides, has however received much less
+attention. We analyse the relevance of the GdFeO3 tilt in detail in a
+representative setting of a partially-filled e g orbital system. We identify a
+new generalised principle of broad relevance, namely, that this tilt acts like
+a structural ""double exchange"" and acts contrary to the well-known
+Anderson-Hasegawa double exchange. As a function of this tilt, therefore, a
+phase transition from a Mott-Hubbard insulator to an incoherent bad-metal
+occurs as an effective band-width-controlled Mott transition. We analyse the
+incoherent metal in detail by studying one- and two-particle spectral responses
+and propose that this selective-metal is a novel orbital analogue of the FL*
+state with fractionalised orbitons. Finally, we apply these ideas to
+qualitatively discuss the effect of strain on thin films of such d-band oxides
+on suitable substrates, and discuss the exciting possibility of engineering
+novel ordered phases, such as unconventional circulating currents, nematics and
+superconductors, by suitable strain engineering in TMO thin films.",1510.04475v1
+2016-03-09,Origin of the kink in the band dispersion of the ferromagnetic perovskite SrRuO3: Electron-phonon coupling,"Perovskite SrRuO3, a prototypical conductive ferromagnetic oxide, exhibits a
+kink in its band dispersion signalling the unusual electron dynamics therein.
+However, the origin of this kink remains elusive. By taking advantage of the
+combo of reactive molecular beam epitaxy and in situ angle-resolved
+photoemission spectroscopy, we systematically studied the evolution of the
+low-energy electronic structure of SrRuO3 films with thickness thinning down to
+nearly two-dimensional limit in a well-controlled way. The kink structure
+persists even in the 4-unit-cell-thick film. Moreover, through quantitative
+self-energy analysis, we observed the negligible thickness dependence of the
+binding energy of the kink, which is in sharp contrast to the downward trend of
+the Curie temperature with reducing the film thickness. Together with
+previously reported transport and Raman studies, this finding suggests that the
+kink of perovskite SrRuO3 should originate from the electron-phonon coupling
+rather than magnetic collective modes, and the in-plane phonons may play a
+dominant role. Considering such a kink structure of SrRuO3 is similar to these
+of many other correlated oxides, we suggest the possible ubiquity of the
+coupling of electrons to oxygen-related phonons in correlated oxides.",1603.03066v1
+2016-10-15,A conducting nano-filament (CNF) network as a precursor to the origin of superconductivity in electron-doped copper oxides,"Emergency of superconductivity at the instabilities of antiferromagnetism has
+been widely recognized in unconventional superconductors. In copper-oxide
+superconductors, spin fluctuations play a predominant role in electron pairing
+with electron dopants yet composite orders veil the nature of superconductivity
+for hole-doped family. However, in electron-doped copper oxide superconductors
+(cuprates) the AFM critical end point is still in controversy for different
+probes, demonstrating high sensitivity to oxygen content. Here, by carefully
+tuning the oxygen content, a systematic study of the Hall signal and
+magnetoresistivity up to 58 Tesla on LCCO thin films identifies two
+characteristic temperatures. The former is quite robust, whereas the latter
+becomes flexible with increasing magnetic field, thereby linking respectively
+to two- and three-dimensional AFM, evident from the multidimensional phase
+diagram as a function of oxygen and Ce dopants. A rigorous theoretical analysis
+of the presented data suggest the existence of conductive nano-filamentary
+structures that effectively corroborate all previously reported field studies.
+The new findings provide a uniquely consistent alternative picture in
+understanding the interactions between AFM and superconductivity in
+electron-doped cuprates and offer a consolidating interpretation to the
+pioneering scaling law in cuprates recently established by Bozovic et al.
+(Nature, 2016)",1610.04788v1
+2017-04-21,Enhancement of electron mobility at oxide interfaces induced by WO3 overlayers,"Interfaces between complex oxides constitute a unique playground for 2D
+electron systems (2DES), where superconductivity and magnetism can arise from
+combinations of bulk insulators. The 2DES at the LaAlO3/SrTiO3 interface is one
+of the most studied in this regard, and its origin is determined by both the
+presence of a polar field in LaAlO3 and the insurgence of point defects, such
+as oxygen vacancies and intermixed cations. These defects usually reside in the
+conduction channel and are responsible for a decreased electronic mobility. In
+this work we use an amorphous WO3 overlayer to control the defect formation and
+obtain an increased electron mobility and effective mass in WO3/LaAlO3/SrTiO3
+heterostructures. The studied system shows a sharp insulator-to-metal
+transition as a function of both LaAlO3 and WO3 layer thickness.
+Low-temperature magnetotransport reveals a strong magnetoresistance reaching
+900% at 10 T and 1.5 K, the presence of multiple conduction channels with
+carrier mobility up to 80 000 cm2/Vs and an unusually high effective mass of
+5.6 me. The amorphous character of the WO3 overlayer makes this a versatile
+approach for defect control at oxide interfaces, which could be applied to
+other heterestrostures disregarding the constraints imposed by crystal
+symmetry.",1704.06522v1
+2018-05-08,Tuning the probability of defect formation via substrate strains in Sr$_2$FeMoO$_6$ films,"Since oxide materials like Sr$_2$FeMoO$_6$ are usually applied as thin films,
+we studied the effect of biaxial strain, resulting from the substrate, on the
+electronic and magnetic properties and, in particular, on the formation energy
+of point defects. From our first-principles calculations, we determined that
+the probability of forming point defects - like vacancies or substitutions - in
+Sr$_2$FeMoO$_6$ could be adjusted by choosing a proper substrate. For example,
+the amount of anti-site disorder can be reduced with compressive strain in
+order to obtain purer Sr$_2$FeMoO$_6$ as needed for spintronic applications,
+while the formation of oxygen vacancies is more likely for tensile strain,
+which improves the functionality of Sr$_2$FeMoO$_6$ as a basis material of
+solid oxide fuel cells. In addition, we were also be able to include the oxygen
+partial pressure in our study by using its thermodynamic connection with the
+chemical potential. Strontium vacancies become for example more likely than
+oxygen vacancies at a pressure of 1$\,$bar. Hence, this degree of freedom might
+offer in general another potential method for defect engineering in oxides
+besides, e.g., experimental growth conditions like temperature or gas pressure.",1805.02969v2
+2012-01-13,High-Tc Superconductivity and Antiferromagnetism in Multilayered Copper Oxides - A New Paradigm of Superconducting Mechanism -,"High-temperature superconductivity (HTSC) in copper oxides emerges on a
+layered CuO2 plane when an antiferromagnetic Mott insulator is doped with
+mobile hole carriers. We review extensive studies of multilayered copper oxides
+by site-selective nuclear magnetic resonance (NMR), which have uncovered the
+intrinsic phase diagram of antiferromagnetism (AFM) and HTSC for a
+disorder-free CuO2 plane with hole carriers. We present our experimental
+findings such as the existence of the AFM metallic state in doped Mott
+insulators, the uniformly mixed phase of AFM and HTSC, and the emergence of
+d-wave SC with a maximum Tc just outside a critical carrier density, at which
+the AFM moment on a CuO2 plane disappears. These results can be accounted for
+by the Mott physics based on the t-J model. The superexchange interaction J_in
+among spins plays a vital role as a glue for Cooper pairs or mobile
+spin-singlet pairs, in contrast to the phonon-mediated attractive interaction
+among electrons established in the Bardeen-Cooper-Schrieffer (BCS) theory. We
+remark that the attractive interaction for raising the $T_c$ of HTSC up to
+temperatures as high as 160 K is the large J_in (~0.12 eV), which binds
+electrons of opposite spins to be on neighboring sites, and that there are no
+bosonic glues. It is the Coulomb repulsive interaction U(> 6 eV) among Cu-3d
+electrons that plays a central role in the physics behind high-Tc phenomena. A
+new paradigm of the SC mechanism opens to strongly correlated electron matter.",1201.2726v1
+2017-06-08,Emergence of quantum critical behavior in metallic quantum-well states of strongly correlated oxides,"Controlling quantum critical phenomena in strongly correlated electron
+systems, which emerge in the neighborhood of a quantum phase transition, is a
+major challenge in modern condensed matter physics. Quantum critical phenomena
+are generated from the delicate balance between long-range order and its
+quantum fluctuation. So far, the nature of quantum phase transitions has been
+investigated by changing a limited number of external parameters such as
+pressure and magnetic field. We propose a new approach for investigating
+quantum criticality by changing the strength of quantum fluctuation that is
+controlled by the dimensional crossover in metallic quantum well (QW)
+structures of strongly correlated oxides. With reducing layer thickness to the
+critical thickness of metal-insulator transition, crossover from a Fermi liquid
+to a non-Fermi liquid has clearly been observed in the metallic QW of SrVO$_3$
+by \textit{in situ} angle-resolved photoemission spectroscopy. Non-Fermi liquid
+behavior with the critical exponent ${\alpha} = 1$ is found to emerge in the
+two-dimensional limit of the metallic QW states, indicating that a quantum
+critical point exists in the neighborhood of the thickness-dependent Mott
+transition. These results suggest that artificial QW structures provide a
+unique platform for investigating novel quantum phenomena in strongly
+correlated oxides in a controllable fashion.",1706.02433v1
+2017-07-02,Ramp Reversal Memory and Phase-Boundary Scarring in Transition Metal Oxides,"Transition metal oxides (TMOs) are complex electronic systems which exhibit a
+multitude of collective phenomena. Two archetypal examples are VO2 and NdNiO3,
+which undergo a metal-insulator phase-transition (MIT), the origin of which is
+still under debate. Here we report the discovery of a memory effect in both
+systems, manifest through an increase of resistance at a specific temperature,
+which is set by reversing the temperature-ramp from heating to cooling during
+the MIT. The characteristics of this ramp-reversal memory effect do not
+coincide with any previously reported history or memory effects in manganites,
+electron-glass or magnetic systems. From a broad range of experimental
+features, supported by theoretical modelling, we find that the main ingredients
+for the effect to arise are the spatial phase-separation of metallic and
+insulating regions during the MIT and the coupling of lattice strain to the
+local critical temperature of the phase transition. We conclude that the
+emergent memory effect originates from phase boundaries at the
+reversal-temperature leaving `scars` in the underlying lattice structure,
+giving rise to a local increase in the transition temperature. The universality
+and robustness of the effect shed new light on the MIT in complex oxides.",1707.00303v1
+2018-10-25,"Exceptionally high, strongly temperature dependent, spin Hall conductivity of SrRuO3","Spin-orbit torques (SOT) in thin film heterostructures originate from strong
+spin-orbit interactions (SOI) that, in the bulk, generate a spin current as the
+result of extrinsic spin-dependent, skew or/and side-jump, scattering, or in
+the intrinsic case due to Berry curvature in the conduction band. While most
+SOT studies have focused on materials with heavy metal components, the oxide
+perovskite SrRuO3 has been predicted to have a pronounced Berry curvature.
+Through quantification of its spin current by the SOT exerted on an adjacent Co
+ferromagnetic layer, we determine that SrRuO3 has a strongly temperature (T)
+dependent spin Hall conductivity which becomes particularly high at low T, e.g.
+\sigma_{SH} \geqslant (\hbar/2e)3x10^{5} \Omega^{-1}m^{-1} at 60 K. Below the
+SrRuO3 ferromagnetic transition, non-standard SOT components develop associated
+with the magnetic characteristics of the oxide, but these do not dominate as
+with spin currents from a conventional ferromagnet. Our results establish a new
+approach for the study of SOI in epitaxial conducting oxide heterostructures
+and confirm SrRuO3 as a promising candidate material for achieving new and
+enhanced spintronics functionalities.",1810.11136v1
+2019-09-18,Optical Absorption Induced by Small Polaron Formation in Transition Metal Oxides -- The Case of Co$_3$O$_4$,"Small polarons (SPs) are known to exist in most important transition metal
+oxides (TMOs); however, the nature of small polaron formation remains
+enigmatic, and a fundamental understanding of how SPs impact the intrinsic
+electronic structure and optical properties of these materials is largely
+lacking. In this work, we employ first-principles calculations to investigate
+SP formation in Co$_{3}$O$_{4}$, a highly promising material for a wide range
+of emerging energy applications, and we resolve the conflicting findings that
+have been reported on the electronic structure of the system. We confirm that
+the intrinsic band gap of Co$_{3}$O$_{4}$ is 1.6 eV, and we show that the
+formation of hole small polarons significantly influences the optical
+absorption spectra, leading to a 0.8 eV transition that is often misinterpreted
+as the band edge that defines the fundamental gap. In addition, we discuss how
+uniaxial strain can be utilized to probe the Jahn-Teller distortion of SP
+states and in turn, effect their optical transitions. Beyond Co$_{3}$O$_{4}$,
+our study suggests a general roadmap for establishing a first-principles
+computational approach that can simultaneously achieve an accurate description
+of SP states, electronic band structure and optical transitions of polaronic
+magnetic oxides.",1909.08653v1
+2019-10-01,Study of second and third harmonic generation from an indium tin oxide nanolayer: influence of nonlocal effects and hot electrons,"We report comparative experimental and theoretical studies of second and
+third harmonic generation from a 20nm-thick indium tin oxide layer in proximity
+of the epsilon-near-zero condition. Using a tunable OPA laser we record both
+spectral and angular dependence of the generated harmonic signals close to this
+particular point. In addition to the enhancement of the second harmonic
+efficiency close to the epsilon-near-zero wavelength, at oblique incidence
+third harmonic generation displays unusual behavior, predicted but not observed
+before. We implement a comprehensive, first-principles hydrodynamic approach
+able to simulate our experimental conditions. The model is unique, flexible,
+and able to capture all major physical mechanisms that drive the electrodynamic
+behavior of conductive oxide layers: nonlocal effects, which blueshift the
+epsilon-near-zero resonance by tens of nanometers; plasma frequency redshift
+due to variations of the effective mass of hot carriers; charge density
+distribution inside the layer, which determines nonlinear surface and magnetic
+interactions; and the nonlinearity of the background medium triggered by bound
+electrons. We show that by taking these contributions into account our
+theoretical predictions are in very good qualitative and quantitative agreement
+with our experimental results. We show that by taking these contributions into
+account our theoretical predictions are in very good qualitative and
+quantitative agreement with our experimental results. We expect that our
+results can be extended to other geometries where ENZ nonlinearity plays an
+important role.",1910.00313v1
+2020-02-25,Emergent electric field control of phase transformation in oxide superlattices,"Electric fields can transform materials with respect to their structure and
+properties, enabling various applications ranging from batteries to
+spintronics. Recently electrolytic gating, which can generate large electric
+fields and voltage-driven ion transfer, has been identified as a powerful means
+to achieve electric-field-controlled phase transformations. The class of
+transition metal oxides (TMOs) provide many potential candidates that present a
+strong response under electrolytic gating. However, very few show a reversible
+structural transformation at room-temperature. Here, we report the realization
+of a digitally synthesized TMO that shows a reversible,
+electric-field-controlled transformation between distinct crystalline phases at
+room-temperature. In superlattices comprised of alternating one-unit-cell of
+SrIrO3 and La0.2Sr0.8MnO3, we find a reversible phase transformation with a 7%
+lattice change and dramatic modulation in chemical, electronic, magnetic and
+optical properties, mediated by the reversible transfer of oxygen and hydrogen
+ions. Strikingly, this phase transformation is absent in the constituent
+oxides, solid solutions and larger period superlattices. Our findings open up a
+new class of materials for voltage-controlled functionality.",2002.10872v1
+2021-01-17,"Comparative analysis for meaningful interpretation of rare-earth oxide M$_{4,5}$ energy loss edges","The magnetic, electronic, and optical properties of rare earth-oxides are
+directly influenced by the valency of the metallic cation. With the development
+of next generation electron energy-loss spectrometers, high-energy lanthanide
+fine structure can be studied with improved signal-to-noise for quantitative
+analysis. Unfortunately, the behavior of rare-earth $4f$ orbital electrons is
+not well understood. To establish best practices for analysis of energy-loss
+spectra from lanthanide oxides, we have performed a comparative study of the
+four traditional white line analysis methods extended to lanthanide $M_{4,5}$
+edges resulting from $3d \rightarrow 4f$ orbital transitions using data from
+Gatan's EELS Atlas. The ${M_4}/{M_5}$ spectral feature ratios were examined as
+a function of $4f$ occupancy. The ${M_4}/{M_5}$ spectral feature ratio
+decreases exponentially as $4f$ occupancy increases, except for a plateau
+between S$\text{m}^{3+}$ and D$\text{y}^{3+}$. The full-width at half the
+maximum intensity of the $M_4$ edges shows increased broadening for
+S$\text{m}^{3+}$ through D$\text{y}^{3+}$. We suggest that the plateau results
+from $4f$ orbital half-filling and is explained through the relationship
+between electron transition probability and transition lifetime as expressed
+through Fermi's Golden Rule. Of the four spectral analysis methods described,
+only the integrated area method can be ascribed a quantitative physical
+interpretation.",2101.06794v1
+2018-07-04,Anomalies Of Phase Diagrams And Physical Properties Of Antiferrodistortive Perovskide Oxides,"The influence of rotomagnetic (RM), rotoelectric (RE) and magnetoelectric
+(ME) coupling on phase diagram and properties of antiferrodistortive (AFD)
+perovskite oxides was reviewed. The main examples we consider in the review are
+typical AFD perovkites, such as incipient ferroelectrics EuTiO3, SrTiO3,
+EuxSr1-xTiO3, multiferroic BiFeO3 and Bi1-xRxFeO3 (x = La, Nd). The strong
+influence of RM, RE and ME couplings on the physical properties and phase
+diagrams including antiferromagnetic (AFM), ferroelectric (FE) and structural
+AFD phases has been revealed in the framework of Landau-Ginzburg-Devonshire
+(LGD) theory, as well as the prediction of novel (double and triple)
+multiferroic phases has been demonstrated.
+  In the review we are especially focused on (a) the possibility to induce FM
+(FE) phase in EuTiO3 (as well as in other paraelectric AFM oxides) by the
+application of an electric (magnetic) field due to the ME coupling; (b) the
+analysis of the size effects and novel phases in EuxSr1-xTiO3 nanosystems,
+where the LGD predicts the presence of the triple AFD-FE-FM(AFM) phase at low
+temperatures; (c) the appearance of improper spontaneous polarization and
+pyroelectricity in the vicinity of antiphase domain boundaries, structural twin
+walls, surfaces and interphases in the AFD phase of non-ferroelectric SrTiO3
+induced by the flexoelectricity and rotostriction; (d) the occurrence of low
+symmetry monoclinic phase with in-plane FE polarization in thin strained
+EuxSr1-xTiO3 films and its stabilization over wide temperature range by AFD
+oxygen octahedron tilts due to flexoelectric and rotostriction coupling; (e)
+discussion of a surprisingly strong size-induced increase of AFM transition
+temperature caused by the joint action of RM coupling with elastic stress
+accumulated in the intergrain spaces of BiFeO3 dense ceramics.",1807.01743v1
+2018-08-14,Impurities and Defects in Mott Systems,"Disorder has intriguing consequences for correlated electronic materials,
+which include several families of high-temperature superconductors and
+resistive switching systems. We address the question of why strongly correlated
+d-wave superconductors, such as the cuprates, prove to be surprisingly robust
+against the introduction of non-magnetic impurities. We show that, very
+generally, both the pair-breaking and the normal state transport scattering
+rates are significantly suppressed by strong correlations effects arising in
+the proximity to a Mott insulating state. We also show that the
+correlation-renormalized scattering amplitude is generically enhanced in the
+forward direction, an effect which was previously often ascribed to the
+specific scattering by charged impurities outside the copper-oxide planes. We
+provide the theoretical insights for resistive switching systems and show how
+impurities and underlying correlations can play significant roles in practical
+devices. We report the striking result of a connection between the resistive
+switching and shock wave formation, a classic topic of non-linear dynamics. We
+argue that the profile of oxygen vacancies that migrate during the commutation
+forms a shock wave that propagates through a highly resistive region of the
+device. We validate the scenario by means of model simulations and experiments
+in a manganese-oxide based memristor device and we extend our theory to the
+case of binary oxides. The shock wave scenario brings unprecedented physical
+insight and enables to rationalize the process of oxygen-vacancy-driven
+resistive change with direct implications for a key technological aspect- the
+commutation speed.",1808.04767v1
+2018-08-21,Two-dimensional Peierls instability via zone boundary Dirac line nodes in layered perovskite oxides,"Interplay of Fermi surface topology and electron correlation is the
+quintessential ingredient underlying spontaneous symmetry breaking in itinerant
+electronic systems. In one-dimensional (1D) systems at half-filling, the
+inherent Fermi surface nesting makes the translationally invariant metallic
+state unstable, which is known as Peierls instability. Extending the scope of
+Peierls instability to two (2D) or three dimensions (3D), however, is not
+straightforward, since the Fermi surface in higher dimensions is generally not
+nested. In this work, we show that a perfectly nested Fermi surface can be
+realized in a class of 2D perovskite oxides, giving rise to 2D Peierls
+instability. Here the central role is played by the zone boundary Dirac line
+node (DLN) protected by two orthogonal glide mirrors induced by the rotation of
+oxygen octahedra. Especially, at a critical angle of the octahedron rotation,
+the zone-boundary DLN flattens, leading to logarithmically diverging
+susceptibility. We propose the 2D Peierls instability driven by dispersionless
+DLN as a principle mechanism for spontaneous symmetry breaking in various
+layered perovskite oxides including the antiferromagnetism of Sr$_2$IrO$_4$. As
+a clear signature of the 2D Peierls instability, we predict that the magnetic
+domain wall in Sr$_2$IrO$_4$ hosts localized soliton modes.",1808.06830v2
+2019-02-05,Chromium Oxide Formation on Nanosecond and Femtosecond Laser Irradiated Thin Chromium Films,"Thin coatings of Chromium oxide have been used for applications as absorbing
+material in solar cells, as protections for magnetic data recording devices and
+as shields in flexible solar cells. Thin coatings of pure chromium were vacuum
+deposited on a glass substrate using hot electrons from tungsten filament.
+These coatings were then treated with a nanosecond and femtosecond laser in
+ambient conditions. The microstructure, morphology and the color of the
+coatings treated with laser sources were modified and there was a formation of
+an oxide layer due to the heat dissipation on the chromium coating from the
+energetic photons. High-resolution scanning electron microscope studies showed
+the morphological evolution that are directly correlated with the laser fluence
+of both the nanosecond and femtosecond lasers. This morphological evolution was
+accompanied by the microstructural change as observed from the x-ray
+diffraction patterns, the chromaticity response of the coating was studied by
+UV-Vis spectrometer and the response of the coating in the visible region
+evolved with the laser fluences. The Rutherford backscattering depth profiling
+of the laser treated coatings revealed the diffusion of oxygen atoms in the
+coating as a result of laser treatment fluence.",1902.01851v4
+2020-08-31,Atomic-scale mechanisms for magnetostriction in CoFe$_2$O$_4$ and La$_{0.5}$Sr$_{0.5}$CoO$_3$ oxides determined by differential x-ray absorption spectroscopy,"The atomic environments involved in the magnetostriction effect in
+CoFe$_2$O$_4$ and La$_{0.5}$Sr$_{0.5}$CoO$_3$ polycrystalline samples have been
+identified by differential extended x-ray absorption fine structure (DiffEXAFS)
+spectroscopy. We demonstrate that cobalt atoms at octahedral sites are
+responsible for their magnetostriction. The analysis of DiffEXAFS data
+indicates that the local-site magnetostrictive strains of Co atoms are reversed
+in these two oxides, in agreement with the macroscopic magnetostriction. For
+the CoFe$_2$O$_4$ spinel, a large negative strain along the (100) direction has
+been determined for the CoO$_6$ octahedron causing a tetragonal contraction in
+contrast with the La$_{0.5}$Sr$_{0.5}$CoO$_3$ perovskite, where a positive
+moderate strain along the (100) direction was found resulting in a tetragonal
+expansion. The different local-site magnetostriction is understood in terms of
+the different valence and spin state of the Co atoms for the two oxides. The
+macroscopicmagnetostriction would be explained then by the relative change in
+volume, either contraction in CoFe$_2$O$_4$ or expansion in
+La$_{0.5}$Sr$_{0.5}$CoO$_3$, when the tetragonal axis of the Co site is
+reoriented under an externally applied magnetic field.",2008.13658v1
+2020-10-23,Maximizing spin-orbit torque efficiency of Ta(O)/Py via modulating oxygen-induced interface orbital hybridization,"Spin-orbit torques due to interfacial Rashba and spin Hall effects have been
+widely considered as a potentially more efficient approach than the
+conventional spin-transfer torque to control the magnetization of ferromagnets.
+We report a comprehensive study of spin-orbit torque efficiency in
+Ta(O)/Ni81Fe19 bilayers by tuning low-oxidation of \b{eta}-phase tantalum, and
+find that the spin Hall angle {\theta}DL increases from ~ -0.18 of the pure
+Ta/Py to the maximum value ~ -0.30 of Ta(O)/Py with 7.8% oxidation.
+Furthermore, we distinguish the efficiency of the spin-orbit torque generated
+by the bulk spin Hall effect and by interfacial Rashba effect, respectively,
+via a series of Py/Cu(0-2 nm)/Ta(O) control experiments. The latter has more
+than twofold enhancement, and even more significant than that of the former at
+the optimum oxidation level. Our results indicate that 65% enhancement of the
+efficiency should be related to the modulation of the interfacial Rashba-like
+spin-orbit torque due to oxygen-induced orbital hybridization cross the
+interface. Our results suggest that the modulation of interfacial coupling via
+oxygen-induced orbital hybridization can be an alternative method to boost the
+change-spin conversion rate.",2010.12253v1
+2021-10-05,Spin-orbit torque generation in NiFe/IrO2 bilayers,"The 5d transition-metal oxides have a unique electronic structure dominated
+by strong spin-orbit coupling and hence they can be an intriguing platform to
+explore spin-current physics. Here, we report on room-temperature generation of
+spin-orbit torque (SOT) from a conductive 5d iridium oxide, IrO2. By measuring
+second-harmonic Hall resistance of Ni81Fe19/IrO2 bilayers, we find both
+dampinglike and fieldlike SOTs. The former is larger than the latter, enabling
+easier control of magnetization. We also observe that the dampinglike SOT
+efficiency has a significant dependence on IrO2 thickness, which is well
+described by the drift-diffusion model based on the bulk spin Hall effect. We
+deduce the effective spin Hall angle of +0.093 +- 0.003 and the spin-diffusion
+length of 1.7 +- 0.2 nm. By comparison with control samples Pt and Ir, we show
+that the effective spin Hall angle of IrO2 is comparable to that of Pt and
+seven times higher than that of Ir. The fieldlike SOT efficiency has a negative
+sign without appreciable dependence on the thickness, in contrast to the
+dampinglike SOT. This suggests that the fieldlike SOT likely stems from the
+interface. These experimental findings suggest that the uniqueness of the
+electronic structure of 5d transition-metal oxides is crucial for highly
+efficient charge to spin-current conversion.",2110.01801v1
+2021-11-26,Room-temperature ferromagnetism at an oxide/nitride interface,"Heterointerfaces have led to the discovery of novel electronic and magnetic
+states because of their strongly entangled electronic degrees of freedom.
+Single-phase chromium compounds always exhibit antiferromagnetism following the
+prediction of Goodenough-Kanamori rules. So far, exchange coupling between
+chromium ions via hetero-anions has not been explored and the associated
+quantum states is unknown. Here we report the successful epitaxial synthesis
+and characterizations of chromium oxide (Cr2O3)-chromium nitride (CrN)
+superlattices. Room-temperature ferromagnetic spin ordering is achieved at the
+interfaces between these two antiferromagnets, and the magnitude of the effect
+decays with increasing layer thickness. First-principles calculations indicate
+that robust ferromagnetic spin interaction between Cr3+ ions via
+anion-hybridizations across the interface yields the lowest total energy. This
+work opens the door to fundamental understanding of the unexpected and
+exceptional properties of oxide-nitride interfaces and provides access to
+hidden phases at low-dimensional quantum heterostructures.",2111.13278v1
+2022-03-06,Two-Dimensional Electron Gas with High Mobility Forming at BaO/SrTiO3 Interface,"Two-dimensional electron gas (2DEG) formed at the interface between two
+insulating oxides offers an opportunity for fundamental research and device
+applications. Binary alkaline earth metal oxides possess compatible lattice
+constants with both silicon and perovskite oxides, exhibiting an enormous
+potential to bridging those two materials classes for multifunctionalities.
+Here we report the formation of 2DEG at the interface between the rock-salt BaO
+and SrTiO3. The highest electron mobility reaches 69000 cm^2 V.S^-1 at 2 K,
+leading to the typical Shubniko de Haas (SdH) oscillations under the high
+magnetic fields. The presence of SdH oscillations at different field-angles
+reveals a quasi-two-dimensional character of the Fermi surface. The
+first-principles calculations suggest that the effective charge transfer from
+the BaO to Ti 3dxy orbital at the interfaces is responsible to the observed
+high carrier mobility. Our results demonstrate that the BaO/STO heterointerface
+is a platform for exploring the correlated quantum phases, opening a door to
+the low-power and mesoscopic electronic devices.",2203.02934v1
+2022-07-14,Braiding lateral morphotropic grain boundary in homogeneitic oxides,"Interfaces formed by correlated oxides offer a critical avenue for
+discovering emergent phenomena and quantum states. However, the fabrication of
+oxide interfaces with variable crystallographic orientations and strain states
+integrated along a film plane is extremely challenge by conventional
+layer-by-layer stacking or self-assembling. Here, we report the creation of
+morphotropic grain boundaries (GBs) in laterally interconnected cobaltite
+homostructures. Single-crystalline substrates and suspended ultrathin
+freestanding membranes provide independent templates for coherent epitaxy and
+constraint on the growth orientation, resulting in seamless and atomically
+sharp GBs. Electronic states and magnetic behavior in hybrid structures are
+laterally modulated and isolated by GBs, enabling artificially engineered
+functionalities in the planar matrix. Our work offers a simple and scalable
+method for fabricating unprecedented innovative interfaces through controlled
+synthesis routes as well as provides a platform for exploring potential
+applications in neuromorphics, solid state batteries, and catalysis.",2207.06566v1
+2023-02-13,Performance of high impedance resonators in dirty dielectric environments,"High-impedance resonators are a promising contender for realizing
+long-distance entangling gates between spin qubits. Often, the fabrication of
+spin qubits relies on the use of gate dielectrics which are detrimental to the
+quality of the resonator. Here, we investigate loss mechanisms of
+high-impedance NbTiN resonators in the vicinity of thermally grown
+SiO\textsubscript{2} and Al\textsubscript{2}O\textsubscript{3} fabricated by
+atomic layer deposition. We benchmark the resonator performance in elevated
+magnetic fields and at elevated temperatures and find that the internal quality
+factors are limited by the coupling between the resonator and two-level systems
+of the employed oxides. Nonetheless, the internal quality factors of
+high-impedance resonators exceed $10^3$ in all investigated oxide
+configurations which implies that the dielectric configuration would not limit
+the performance of resonators integrated in a spin-qubit device. Because these
+oxides are commonly used for spin qubit device fabrication, our results allow
+for straightforward integration of high-impedance resonators into spin-based
+quantum processors. Hence, these experiments pave the way for large-scale,
+spin-based quantum computers.",2302.06303v2
+2023-04-10,"Spin-phonon interactions and magnetoelectric coupling in Co$_4$$B_2$O$_9$ ($B$ = Nb, Ta)","In order to explore the consequences of spin-orbit coupling on spin-phonon
+interactions in a set of chemically-similar mixed metal oxides, we measured the
+infrared vibrational properties of Co$_4B_2$O$_9$ ($B$ = Nb, Ta) as a function
+of temperature and compared our findings with lattice dynamics calculations and
+several different models of spin-phonon coupling. Frequency vs. temperature
+trends for the Co$^{2+}$ shearing mode near 150 cm$^{-1}$ reveal significant
+shifts across the magnetic ordering temperature that are especially large in
+relative terms. Bringing these results together and accounting for
+noncollinearity, we obtain spin-phonon coupling constants of -3.4 and -4.3
+cm$^{-1}$ for Co$_4$Nb$_2$O$_9$ and the Ta analog, respectively. Analysis
+reveals that these coupling constants derive from interlayer (rather than
+intralayer) exchange interactions and that the interlayer interactions contain
+competing antiferromagnetic and ferromagnetic contributions. At the same time,
+beyond-Heisenberg terms are minimized due to fortuitous symmetry
+considerations, different than most other 4$d$- and 5$d$-containing oxides.
+Comparison with other contemporary oxides shows that spin-phonon coupling in
+this family of materials is among the strongest ever reported, suggesting an
+origin for magnetoelectric coupling.",2304.04865v1
+2023-06-30,3D oxygen vacancy order and defect-property relations in multiferroic (LuFeO$_3$)$_9$/(LuFe$_2$O$_4$)$_1$ superlattices,"Oxide heterostructures exhibit a vast variety of unique physical properties.
+Examples are unconventional superconductivity in layered nickelates and
+topological polar order in (PbTiO$_3$)$_n$/(SrTiO$_3$)$_n$ superlattices.
+Although it is clear that variations in oxygen content are crucial for the
+electronic correlation phenomena in oxides, it remains a major challenge to
+quantify their impact. Here, we measure the chemical composition in
+multiferroic (LuFeO$_3$)$_9$/(LuFe$_2$O$_4$)$_1$ superlattices, revealing a
+one-to-one correlation between the distribution of oxygen vacancies and the
+electric and magnetic properties. Using atom probe tomography, we observe
+oxygen vacancies arranging in a layered three-dimensional structure with a
+local density on the order of 10$^{14}$ cm$^{-2}$, congruent with the
+formula-unit-thick ferrimagnetic LuFe$_2$O$_4$ layers. The vacancy order is
+promoted by the locally reduced formation energy and plays a key role in
+stabilizing the ferroelectric domains and ferrimagnetism in the LuFeO$_3$ and
+LuFe$_2$O$_4$ layers, respectively. The results demonstrate the importance of
+oxygen vacancies for the room-temperature multiferroicity in this system and
+establish an approach for quantifying the oxygen defects with atomic-scale
+precision in 3D, giving new opportunities for deterministic defect-enabled
+property control in oxide heterostructures.",2307.00139v1
+2015-08-08,Emergent excitation at the magnetic metal-insulator transition in the pyrochlore osmate Cd2Os2O7,"The rich physics manifested by 5d oxides falls outside the Mott-Hubbard
+paradigm used to successfully explain the electronic and magnetic properties of
+3d oxides. Much consideration has been given to the extent to which strong
+spin-orbit coupling (SOC), in the limit of increased bandwidth and reduced
+electron correlation, drives the formation of novel electronic states, as
+manifested through the existence of metal-insulator transitions (MITs). SOC is
+believed to play a dominant role in 5d5 systems such as iridates (Ir4+),
+undergoing MITs which may or may not be intimately connected to magnetic order,
+with pyrochlore and perovksite systems being examples of the former and latter,
+respectively. However, the role of SOC for other 5d configurations is less
+clear. For example, 5d3 (e.g Os5+) systems are expected to have an orbital
+singlet and consequently a reduced effect of SOC in the groundstate. The
+pyrochlore osmate Cd2Os2O7 nonetheless exhibits a MIT intimately entwined with
+magnetic order with phenomena similar to pyrochlore iridates. Here we report
+the first resonant inelastic X-ray scattering (RIXS) measurements on an osmium
+compound, allowing us to determine the salient electronic and magnetic energy
+scales controlling the MIT in Cd2Os2O7, which we benchmark against detailed
+quantum chemistry calculations. In particular, we reveal the emergence at the
+MIT of a magnetic excitation corresponding to a superposition of multiple
+spin-flip processes from an Ising-like all-in/all-out magnetic groundstate. We
+discuss our results with respect to the role of SOC in magnetically mediated
+MITs in 5d systems",1508.01848v1
+2019-06-18,Multi-analytical characterization of Fe-rich magnetic inclusions in diamonds,"Magnetic mineral inclusions, as iron oxides or sulfides, occur quite rarely
+in natural diamonds. Nonetheless, they represent a key tool not only to unveil
+the conditions of formation of host diamonds, but also to get hints about the
+paleointensity of the geomagnetic field present at times of the Earth's history
+otherwise not accessible. This possibility is related to their capability to
+carry a remanent magnetization dependent on their magnetic history. However,
+comprehensive experimental studies on magnetic inclusions in diamonds have been
+rarely reported so far. Here we exploit X-ray diffraction, Synchrotron-based
+X-ray Tomographic Microscopy and Alternating Field Magnetometry to determine
+the crystallographic, morphological and magnetic properties of ferrimagnetic
+Fe-oxides entrapped in diamonds coming from Akwatia (Ghana). We exploit the
+methodology to estimate the natural remanence of the inclusions, associated to
+the Earth's magnetic field they experienced, and to get insights on the
+relative time of formation between host and inclusion systems. Furthermore,
+from the hysteresis loops and First Order Reversal Curves we determine
+qualitatively the anisotropy, size and domain state configuration of the
+magnetic grains constituting the inclusions.",1906.07641v3
+2001-08-17,Magnetic and charge structures in itinerant-electron magnets: Coexistence of multiple SDW and CDW,"A theory of Kondo lattices is applied to studying possible magnetic and
+charge structures of itinerant-electron antiferromagnets. Even helical spin
+structures can be stabilized when the nesting of the Fermi surface is not sharp
+and the superexchange interaction, which arises from the virtual exchange of
+pair excitations across the Mott-Hubbard gap, is mainly responsible for
+magnetic instability. Sinusoidal spin structures or spin density waves (SDW)
+are only stabilized when the nesting of the Fermi surface is sharp enough and a
+novel exchange interaction arising from that of pair excitations of
+quasi-particles is mainly responsible for magnetic instability. In particular,
+multiple SDW are stabilized when their incommensurate ordering wave-numbers
+$\pm{\bf Q}$ are multiple; magnetizations of different $\pm{\bf Q}$ components
+are orthogonal to each other in double and triple SDW when magnetic anisotropy
+is weak enough. Unless $\pm 2{\bf Q}$ are commensurate, charge density waves
+(CDW) with $\pm 2{\bf Q}$ coexist with SDW with $\pm{\bf Q}$. Because the
+quenching of magnetic moments by the Kondo effect depends on local numbers of
+electrons, the phase of CDW or electron densities is such that magnetic moments
+are large where the quenching is weak. It is proposed that the so called stipe
+order in cuprate-oxide high-temperature superconductors must be the coexisting
+state of double incommensurate SDW and CDW.",0108270v1
+2008-12-30,Covalent bonding and magnetism in cuprates,"The importance of covalent bonding for the magnetism of 3d metal complexes
+was first noted by Pauling in 1931. His point became moot, however, with the
+success of the ionic picture of Van Vleck, where ligands influence magnetic
+electrons of 3d ions mainly through electrostatic fields. Anderson's theory of
+spin superexchange later established that covalency is at the heart of
+cooperative magnetism in insulators, but its energy scale was believed to be
+small compared to other inter-ionic interactions and therefore it was
+considered a small perturbation of the ionic picture. This assertion fails
+dramatically in copper oxides, which came to prominence following the discovery
+of high critical temperature superconductors (HTSC). Magnetic interactions in
+cuprates are remarkably strong and are often considered the origin of the
+unusually high superconducting transition temperature, Tc. Here we report a
+detailed survey of magnetic excitations in the one-dimensional cuprate Sr2CuO3
+using inelastic neutron scattering (INS). We show that although the
+experimental dynamical spin structure factor is well described by the model
+S=1/2 nearest-neighbour Heisenberg Hamiltonian typically used for cuprates, the
+magnetic intensity is modified dramatically by strong hybridization of Cu 3d
+states with O p states, showing that the ionic picture of localized 3d
+Heisenberg spin magnetism is grossly inadequate. Our findings provide a natural
+explanation for the puzzle of the missing INS magnetic intensity in cuprates
+and have profound implications for understanding current and future
+experimental data on these materials.",0812.5007v1
+2019-05-13,Electronic structure of Fe and magnetism in the $3d/5d$ double perovskites Ca$_2$FeReO$_6$ and Ba$_2$FeReO$_6$,"The Fe electronic structure and magnetism in (i) monoclinic Ca$_2$FeReO$_6$
+with a metal-insulator transition at $T_{MI} \sim 140$ K and (ii) quasi-cubic
+half-metallic Ba$_2$FeReO$_6$ ceramic double perovskites are probed by soft
+x-ray absorption spectroscopy (XAS) and magnetic circular dichroism (XMCD).
+These materials show distinct Fe $L_{2,3}$ XAS and XMCD spectra, which are
+primarily associated with their different average Fe oxidation states (close to
+Fe$^{3+}$ for Ca$_2$FeReO$_6$ and intermediate between Fe$^{2+}$ and Fe$^{3+}$
+for Ba$_2$FeReO$_6$) despite being related by an isoelectronic
+(Ca$^{2+}$/Ba$^{2+}$) substitution. For Ca$_2$FeReO$_6$, the powder-averaged Fe
+spin moment along the field direction ($B = 5$ T), as probed by the XMCD
+experiment, is strongly reduced in comparison with the spontaneous Fe moment
+previously obtained by neutron diffraction, consistent with a scenario where
+the magnetic moments are constrained to remain within an easy plane. For $B=1$
+T, the unsaturated XMCD signal is reduced below $T_{MI}$ consistent with a
+magnetic transition to an easy-axis state that further reduces the
+powder-averaged magnetization in the field direction. For Ba$_2$FeReO$_6$, the
+field-aligned Fe spins are larger than for Ca$_2$FeReO$_6$ ($B=5$ T) and the
+temperature dependence of the Fe magnetic moment is consistent with the
+magnetic ordering transition at $T_C^{Ba} = 305$ K. Our results illustrate the
+dramatic influence of the specific spin-orbital configuration of Re $5d$
+electrons on the Fe $3d$ local magnetism of these Fe/Re double perovskites.",1905.04988v1
+2020-07-08,"Probing low temperature non-equilibrium magnetic state in Co$_{2.75}$Fe$_{0.25}$O$_{4+δ}$ spinel oxide using dc magnetization, ac susceptibility and neutron diffraction experiments","The low temperature lattice structure and magnetic properties of
+Co$_{2.75}$Fe$_{0.25}$O$_4$ ferrite have been investigated using experimental
+results from synchrotron x-ray diffraction (SXRD), dc magnetization, ac
+susceptibility, neutron diffraction and neutron depolarization techniques. The
+samples have been prepared by chemical co-precipitation of the Fe and Co
+nitrates solution in high alkaline medium and subsequent thermal annealing of
+the precipitates in the temperature range of 200- 900 $^\circ$C. Rietveld
+refinement of the SXRD patterns at room temperature indicated two-phased cubic
+spinel structure for the samples annealed at temperatures 200-600 $^\circ$C.
+The samples annealed at temperatures 700 $^\circ$C and 900 $^\circ$C (CF90)
+have been best fitted with single phased lattice structure. Refinement of the
+neutron diffraction patterns in the temperature range of 5-300 K confirmed
+antiferromagnetic (AFM) Co$_3$O$_4$ and ferrimagnetic (FIM)
+Co$_{2.75}$Fe$_{0.25}$O$_4$ phases for the sample annealed at 600 $^\circ$C and
+single FIM phase of Co$_{2.75}$Fe$_{0.25}$O$_4$ for the CF90 sample. Magnetic
+measurements have shown a non-equilibrium magnetic structure, consisting of the
+high temperature FIM phase and low temperature AFM phase. The magnetic phases
+are sensitive to magnetic fields, where high temperature phase is suppressed at
+higher magnetic fields by enhancing the low temperature AFM phase, irrespective
+of annealing temperature of the samples.",2007.03906v1
+2016-05-17,"Magnetism of a rhombohedral-type pyrochlore-derived Kagome series, Mn2R3Sb3O14 (R= Rare-earths)","The results of magnetic investigations on a new series of compounds,
+Mn2R3Sb3O14, containing 2-dimensional Kagome lattice of R ions and belonging to
+pyrochlore series, are presented. Crystallographic features of light R members
+(R= La, Pr and Nd) of this family, as established in the recent literature,
+have been reported to be novel in many respects, in particular, the rhomohedral
+nature of the structure which is rare among pyrochlores. It was also reported
+that, as the R becomes heavier, beyond R= Sm, the fraction of well-known cubic
+pyrochlore phase tends to gradually dominate. Here, we report that we are able
+to form the Gd member in the rhombohedral form without noticeable admixture
+from the cubic phase. With respect to magnetic behavior, our magnetization
+measurements on the La member reveal that Mn exists in divalent state without
+any evidence for long range magnetic ordering down to 2 K (that is, suppressed
+magnetism), which is not so common for Mn based oxides, though
+antiferromagnerism below 2 K is not ruled out. Nd and Gd members, are however,
+found to show distinct features above 2 K in magnetic susceptibility and
+heat-capacity, attributable to long-range magnetic ordering from respective
+rare-earth sublattice. The experimental results with respect to magnetism are
+found to be consistent with the results from ab initio band structure
+calculations performed for the La case. The calculations imply that electron
+correlation is important to describe insulating behavior.",1605.05027v1
+2021-05-01,Anisotropy and Current Control of Magnetization in SrRuO$_3$ SrTiO$_3$ Heterostructures for Spin-Memristors,"Spintronics-based nonvolatile components in neuromorphic circuits offer the
+possibility of realizing novel functionalities at low power. Current-controlled
+electrical switching of magnetization is actively researched in this context.
+Complex oxide heterostructures with perpendicular magnetic anisotropy (PMA),
+consisting of SrRuO$_3$ (SRO) grown on SrTiO$_3$ (STO) are strong material
+contenders. Utilizing the crystal orientation, magnetic anisotropy in such
+simple heterostructures can be tuned to either exhibit a perfect or slightly
+tilted PMA. Here, we investigate current-induced magnetization modulation in
+such tailored ferromagnetic layers with a material with strong spin-orbit
+coupling (Pt), exploiting the spin Hall effect. We find significant differences
+in the magnetic anisotropy between the SRO/STO heterostructures, as manifested
+in the first and second harmonic magnetoresistance measurements.
+Current-induced magnetization switching can be realized with spin-orbit
+torques, but for systems with perfect PMA this switching is probabilistic as a
+result of the high symmetry. Slight tilting of the PMA can break this symmetry
+and allow the realization of deterministic switching. Control over the magnetic
+anisotropy of our heterostructures therefore provides control over the manner
+of switching. Based on our findings, we propose a three-terminal spintronic
+memristor, with a magnetic tunnel junction design, that shows several resistive
+states controlled by electric charge. Non-volatile states can be written
+through SOT by applying an in-plane current, and read out as a tunnel current
+by applying a small out-of-plane current. Depending on the anisotropy of the
+SRO layer, the writing mechanism is either deterministic or probabilistic
+allowing for different functionalities to emerge. We envisage that the
+probabilistic MTJs could be used as synapses while the deterministic devices
+can emulate neurons",2105.00269v1
+2021-08-25,Magnetic properties of BiFeO$_3$-BaTiO$_3$ ceramics in the morphotropic phase boundary: a role of crystal structure and structural parameters,"A correlation between the crystal structure and magnetic properties of system
+(1-x)BiFeO$_3$-(x)BaTiO$_3$ with compounds across the morphotropic phase
+boundary was studied using X-ray and neutron diffraction, magnetometry, and
+Mossbauer spectroscopy measurements. Increase in the dopants content leads to
+the structural transition from the rhombohedral phase to the cubic phase via a
+formation of the two-phase region (0.2 < x < 0.33), wherein the magnetic
+structure changes from the modulated G-type antiferromagnetic to the collinear
+antiferromagnetic via a stabilization of the non-collinear antiferromagnetic
+phase with non-zero remanent magnetization. The value of magnetic moment
+calculated per iron ion based on the Mossbauer and neutron diffraction data
+decreases from m = 4.4 mB for the compound with x=0.25 to m=3.2 mB for the
+compound with x=0.35 testifying a dominance of 3+ oxidation state of the iron
+ions. Increase in the amount of the cubic phase leads to a reduction in the
+remanent magnetization from 0.02 emu.g for the compounds with the dominant
+rhombohedral phase (x < 0.27) down to about 0.001 emu/g for the compounds with
+dominant cubic structure (x >= 0.27). Rapid decrease in the remanent
+magnetization observed in the compounds across the phase coexistence region
+points at no direct correlation between the type of structural distortion and
+non-zero remanent magnetization, while the oxygen octahedra tilting is the key
+factor determining the presence of non-zero remanent magnetization.",2108.11447v1
+2023-02-23,First-principles based Monte Carlo modeling of oxygen deficient Fe-substituted SrTiO$_3$ experimental magnetization,"Ferroics based on transition-metal (TM) substituted SrTiO$_{3}$ have called
+much attention as magnetism and/or ferroelectricity can be tuned by using
+cations substitution and defects, strain and/or oxygen deficiency. C. A. Ross
+et al. [Phys. Rev. Applied 7, 024006 (2017)] demonstrated the
+SrTi$_{1-x}$Fe$_{x}$O$_{3-\delta}$ (STF) magnetization behavior for different
+deposition oxygen-pressures, substrates and magnetic fields. The relation
+between oxygen deficiency and ferroic orders is yet to be well understood, for
+which the full potential of oxygen-stoichiometry engineered materials remain an
+open question. Here, we use hybrid-DFT to calculate different oxygen vacancy
+($v_{o}$) states in STF with a variety of TM distributions. The resulting
+cations' magnetic states and alignments associated to the $v_{o}$ ground-states
+for $x=\{0.125,0.25\}$ are used within a Monte Carlo scope for collinear
+magnetism to simulate the spontaneous magnetization. Our model captures several
+experimental STF features i.e., display a maximum of the magnetization at
+intermediate number of vacancies, a monotonous quenching from
+$\sim{0.35}\mu{_{B}}$ for small ${\delta}$, and a slower decreasing of such
+saturation for larger number of vacancies. Moreover, our approach gives a
+further insight into the relations between defects stabilization and
+magnetization, vacancy density and the oxygen pressure required to maximize
+such ferroic order, and sets guidelines for future Machine Learning based
+computational synthesis of multiferroic oxides.",2302.12174v1
+1996-11-30,Slow antiferromagnetic dynamics in the low temperature tetragonal phase of La_{2-x}Sr_xCuO_4 as revealed by ESR of Gd spin probes,"Measuring the ESR of Gd spin probes we have studied the magnetic properties
+of the copper oxide planes in the low temperature tetragonal (LTT) phase of Eu
+doped La_{2-x}Sr_xCuO_4. The data give evidence that at particular levels of Sr
+and Eu doping the frequency of the antiferromagnetic fluctuations in the LTT
+phase dramatically decreases at low temperatures by almost three orders of
+magnitude. However, no static magnetic order has been found for T>8K in
+contrast to the observation by neutron scattering of stripe ordering of spins
+below 50K in a Nd doped La_{2-x}Sr_xCuO_4 single crystal. To our opinion static
+order in the Nd doped compound is induced due to the interaction between the Cu
+spins with the rare earth magnetic moments. Therefore, a really characteristic
+property of the magnetism in the LTT structural phase may be not static
+magnetic order at elevated temperatures but rather extremely slow
+antiferromagnetic dynamics.",9612011v1
+1999-02-16,Dependence of Magnetic Anisotropy and Magnetoresistance of Ni81Fe19-Films on Annealing,"Permalloy (Py:Ni81Fe19) exhibits an anisotropic magnetoresistance (AMR) which
+is very often used to read magnetic signals from storage devices. Py-films of
+thickness 20nm were prepared by dc-magnetron sputtering in a magnetic field
+onto thermally oxidized Si-wafers and annealed ex situ at temperatures up to
+1000K in order to investigate the dependence of the magnetic anisotropy and the
+AMR on heat treatments. The films exhibit an uniaxial anisotropy after
+preparation which changes during annealing above 520K. The AMR along the former
+magnetically easy axis as well as the corresponding field sensitivity are
+increased by a heat treatment around 700K reaching maxima of about 8% and a
+maximum sensitivity of 1.5%/Oe, respectively. We discuss possible sources for
+the change in anisotropy, i.e. strain effects, inhomogeneities, and changes of
+the local atomic order.",9902222v1
+2001-10-01,"Importance of Magnetism in Phase Stability, Equations of State, and Elasticity","The effects of magnetism on high pressure properties of transition metals and
+transition metal compounds can be quite important. In the case of Fe, magnetism
+is responsible for stability of the body-centered cubic (bcc) phase at ambient
+conditions, and the large thermal expansivity in face-centered cubic (fcc)
+iron, and also has large effects on the equation of state and elasticity of
+hexagonal close-packed (hcp) iron. In transition metal oxides, local magnetic
+moments are responsible for their insulating behavior. LDA+U results are
+presented for CoO and FeO, and predictions are made for high pressure
+metallization. The inclusion of a local Coulomb repulsion, U, greatly inhibits
+the high-spin low-spin transitions found with conventional exchange-correlation
+functionals (i.e. generalized gradient corrections, GGA). We discuss theory and
+computations for the effects of magnetism on high pressure cohesive properties.",0110025v5
+2004-12-22,Role of Point Defects on the Properties of Manganites,"La1-xCaxMnO3+delta and La1-xNaxMnO3+delta samples with well defined cation
+molecularity and oxygen contents are analyzed with XRPD, electrical
+conductivity, electron paramagnetic resonance and static magnetization
+measurements. Point defects are introduced in the structure by: i) aliovalent
+cation doping (substitutional defects), ii) oxygen over-stoichiometry (cation
+vacancies) and iii) oxygen under-stoichiometry (oxygen vacancies). The cation
+doping mainly influences the material by affecting the tolerance factor and the
+oxidation of the Mn ions; the cation vacancies affect the magnetic properties
+by interrupting the interaction paths between Mn4+-Mn3+ ions whereas the oxygen
+vacancies have a stronger influence on the structural and electrical properties
+and act on the magnetic properties by the overall decrease on the Mn4+ amount
+and by the creation of sample regions with different magnetic features. We can
+state that the basic magnetic and electrical behaviors of the Ca- and Na-doped
+lanthanum manganite compounds are driven from the Mn4+-Mn3+ ratio and all the
+peculiar behaviors are indeed caused by defects, concentration gradient and,
+more generally, by lattice disorder.",0412606v1
+2005-04-08,On the crystal field in the modern solid-state theory,"We point out the high physical correctness of the use and the concept of the
+crystal-field approach, even if is used to metallic magnetic materials of
+transition-metal 3d/4f/5f compounds. We discuss the place of the crystal-field
+theory in modern solid-state physics and we point out the necessity to consider
+the crystal-field approach with the spin-orbit coupling and strong electron
+correlations, as a contrast to the single-electron version of the crystal field
+customarily used for 3d electrons. We have extended the strongly-correlated
+crystal-field theory to a Quantum Atomistic Solid-State Theory (QUASST) to
+account for the translational symmetry and inter-site spin-dependent
+interactions indispensable for formation of magnetically-ordered state. We have
+correlated macroscopic magnetic and electronic properties with the atomic-scale
+electronic structure for ErNi5, UPd2Al3, FeBr2, LaCoO3 and LaMnO3. In QUASST we
+have made unification of 3d and rare-earth compounds in description of the
+low-energy electronic structures and magnetism of open 3d-/4f-/5f-shell
+electrons. QUASST offers consistent description of zero-temperature properties
+and thermodynamic properties of 4f-/5f-/3d-atom containing compounds. Our
+studies indicate that it is the highest time to unquench the orbital magnetism
+in 3d oxides.",0504199v1
+2006-01-19,Enhancement of giant magnetoresistance effect in the Ruddlesden-Popper phase Sr3Fe2-xCoxO7-d: Predominant role of oxygen nonstoichiometry and magnetic phase separation,"The magnetic and magnetotransport properties of the Sr3Fe2-xCoxO7-d system
+(0.2 <= x <= 1.0) were systematically investigated. This oxide system exhibits
+a giant magnetoresistance (GMR) effect at low temperatures, reaching up to 80%
+in 7 T at 5 K. Ac-susceptibility measurements show that there exists a strong
+competition between ferromagnetic (F) and spin glass states, and the balance
+between these two magnetic states can be controlled by varying cobalt (x)
+and/or oxygen contents (d). Importantly, the MR effect is closely related to
+the magnetic property: the development of magnetic disordering leads to
+enhancement in the negative MR effect. It is suggested that the compound
+segregates into F clusters embedded in a non-F matrix, being a naturally
+occurring analog of the artificial granular-GMR materials, as in the doped
+perovskite cobaltites, La1-xSrxCoO3 (x < 0.18).",0601428v1
+2006-01-22,GHz sandwich strip inductors based on Fe-N Films,"Planar strip inductors consisting of two Fe-N films enclosing a conducting
+film made of Cu, were fabricated on oxidized Si substrates. The inductors were
+1mm long, 2 to 100 um wide, with layers of thickness ~0.1 um for the magnetic
+films and ~0.5 um for the conductor. The soft (Hc=4-8 Oe) magnetic layers were
+biased during impedance measurement by applying an external field along the
+strip length thereby facilitating the transverse susceptibility configuration.
+Biased strips exhibited 70 to 100% inductance enhancement at 1GHz with quality
+factors Q=4.5 to 3, respectively. The magnetic contribution to the total flux
+in the narrow devices was less than predicted theoretically, which was
+attributed to hardening of the magnetic material at the edges of the strip,
+where the deposition was close to 60 degree incidence. Test films were
+fabricated on tilted substrates and found to develop a very high anisotropy (up
+to 1 kOe) for deposition angles larger than 30 degrees. Optimizing the flux
+closure at the strip edges and using thicker conductor layers is essential for
+further improving the performance of sandwich strip inductors.",0601497v1
+2007-08-13,On the absence of a spiral magnetic order in Li2CuO2 with one-dimensional CuO2 ribbon chains,"On the basis of first principles density functional theory electronic
+structure calculations as well as classical spin analysis, we explored why the
+magnetic oxide Li2CuO2, consisting of CuO2 ribbon chains made up of
+edge-sharing CuO4 squares, does not exhibit a spiral-magnetic order. Our work
+shows that, due to the next-nearest-neighbor interchain interactions, the
+observed collinear magnetic structure becomes only slightly less stable than
+the spin-spiral ground state, and many states become nearly degenerate in
+energy with the observed collinear structure. This suggests that the collinear
+magnetic structure of Li2CuO2 is a consequence of order-by-disorder induced by
+next-nearest-neighbor interchain interactions.",0708.1708v1
+2007-09-21,"Self-assembly of polymers or copolymers and ferrofluids leading to either 1-d, 2-d or 3-d aggregates decorated with magnetic nanoparticles","A novel type of hybrid colloids is presented, based on the association of
+several polymeric systems and ferrofluids. On the one hand, we use inorganic
+nanoparticles made of magnetic iron oxide prepared at the LI2C, which response
+to a magnetic field of low intensity. On the other hand the organic part is
+made either of long linear polyacrylamide chains or of mesoscopic structures
+(vesicles and micelles) self-assembled from amphiphile
+polybutadiene-b-poly(glutamic acid) di-block copolymers, which conformation is
+pH-sensitive.",0709.3514v1
+2008-04-24,Magnetic states at the Oxygen surfaces of ZnO and Co-doped ZnO,"First principles calculations of the O surfaces of Co-ZnO show that
+substitutional Co ions develop large magnetic moments which long-range coupling
+depends on their mutual distance. The local spin polarization induced at the O
+atoms is three times larger at the surface than in the bulk, and the surface
+stability is considerably reinforced by Co. Moreover, a robust ferromagnetic
+state is predicted at the Oxygen (0001) surface even in the absence of magnetic
+atoms. The occurrence of surface magnetic moments correlates with the number of
+{\it p}-holes in the valence band of the oxide, and the distribution of the
+magnetic charge is, even in the absence of spin-orbit interaction, highly
+anisotropic.",0804.3937v1
+2008-05-06,"Decisive Influence of Cation Size on the Magnetic Groundstate and Non-Fermi Liquid Behavior of ARuO3 (A = Ca, Sr)","We report calorimetric, magnetic and electric transport properties of
+single-crystal CaRuO3 and SrRuO3 as a function of temperature T and applied
+magnetic field B. We find that CaRuO3 is a non-Fermi-liquid metal near a
+magnetic instability, as characterized by the following properties: (1) the
+heat capacity C(T,B) ~ -T log T is readily enhanced in low applied fields, and
+exhibits a Schottky peak at 2.3 K that exhibits field dependence when T is
+reduced; (2) the magnetic susceptibility diverges as T^-x at low temperatures
+with 1/2 < x < 1, depending on the applied field; and (3) the electrical
+resistivity exhibits a T3/2 dependence over the range 1.7 < T < 24 K. No
+Shubnikov-de Haas oscillations are discerned at T = 0.65 K for applied fields
+up to 45 T. These properties, which sharply contrast those of the itinerant
+ferromagnet SrRuO3, indicate CaRuO3 is a rare example of a stoichiometric oxide
+compound that exhibits non-Fermi-liquid behavior near a quantum critical point.",0805.0741v1
+2008-11-13,Magnetism in a TiO2/LaAlO3 heterostructure: an ab initio study about the role of oxygen vacancies,"In this work we study the electronic structure and magnetism of a TiO2 film
+grown on another non-magnetic oxide such as a LaAlO3 (001) substrate,
+concentrating on the role played by structural relaxation and oxygen vacancies.
+Using Density Functional Theory ab-initio methods, we study the free-standing
+anatase film as well as the interfaces with either the LaO or AlO2 planes of
+LaAlO3, focusing on the possibility of magnetic solutions. Our results show
+that the interface LaO/TiO2 is favored against the AlO2/TiO2 one if no oxygen
+vacancies are present in the interface whereas the contrary happens when there
+are oxygen vacancies. In both cases, the cohesive energy is of the same order
+of magnitude but only the AlO2/TiO2 interface presents an stable magnetic
+solution.",0811.2172v1
+2009-07-23,Electrostatic co-assembly of magnetic nanoparticles and fluorescent nanospheres: a versatile approach toward bimodal nanorods,"The elaboration of multimodal nanoparticles stimulates tremendous interest
+owing to their numerous potentialities in many applicative fields like
+optoelectronics, photonics and especially bioimaging. The concomitant
+association of various properties (optical, electrochemical, magnetic) allows
+for the use of complementary stimuli in order to probe the interactions between
+the nanoparticles and their surroundings.Nanoparticles (NPs) have thus become
+highly praised tools to image cells and tissues with a large contrast
+compatible with the dimensions of biological materials and the existence of
+quantum confinement effects induced by the reduced dimensions. In this context,
+the combination of magnetism and emissive properties such as fluorescence
+appears particularly attractive for non-invasive investigations, cell sorting
+or drug vectorization. Therefore, combining both fluorescence and magnetism
+requires the delicate construction of hybrid assemblies. Most of the magnetic
+nanoparticles are made of metallic oxides or alloys, e.g. gamma-Fe2O3, Fe3O4,
+FePt, while the target fluorescent entities are often organic dyes or quantum
+dots (QDs).",0907.3979v1
+2009-11-09,Role of dipole-dipole interactions in multiple quantum transitions in magnetic nanoparticles,"In order to better understand the origin of multiple quantum transitions
+observed in superparamagnetic nanoparticles, electron magnetic resonance (EMR)
+studies have been performed on iron oxide nanoparticles assembled inside the
+anodic alumina membrane. The positions of both the main resonance and
+""forbidden"" (double-quantum, 2Q) transitions observed at the half-field
+demonstrate the characteristic angular dependence with the line shifts
+proportional to 3cos2q-1, where q is the angle between the channel axis and
+external magnetic field B. This result can be attributed to the interparticle
+dipole-dipole interactions within elongated aggregates inside the channels. The
+angular dependence of the 2Q intensity is found to be proportional to
+sin2qcos2q, that is consistent with the predictions of quantum-mechanical
+calculations with the account for the mixing of states by non-secular
+inter-particle dipole-dipole interactions. Good agreement is demonstrated
+between different kinds of measurements (magnetization curves, line shifts and
+2Q intensity), evidencing applicability of the quantum approach to the
+magnetization dynamics of superparamagnetic objects.",0911.1752v1
+2011-01-12,Multiferroic Properties of CaMn$_7$O$_{12}$,"We report that CaMn$_7$O$_{12}$ is a new magnetic multiferroic material. The
+appearance of a ferroelectric polarization coinciding with the magnetic phase
+transition ($\sim90$ K) suggests the presence of ferroelectricity induced by
+magnetism, further confirmed by its strong magnetoelectric response. With
+respect to other known magnetic multiferroics, CaMn$_7$O$_{12}$ displays
+attractive multiferroic properties, such as a high ferroelectric critical
+temperature and large polarization. More importantly, these results open a new
+avenue to search for magnetic multiferroics in the catalogue of doped oxides.",1101.2276v4
+2011-02-24,The role of magnetic anisotropy in spin filter junctions,"We have fabricated oxide based spin filter junctions in which we demonstrate
+that magnetic anisotropy can be used to tune the transport behavior of spin
+filter junctions. Until recently, spin filters have been largely comprised of
+polycrystalline materials where the spin filter barrier layer and one of the
+electrodes are ferromagnetic. These spin filter junctions have relied on the
+weak magnetic coupling between one ferromagnetic electrode and a barrier layer
+or the insertion of a nonmagnetic insulating layer in between the spin filter
+barrier and electrode. We have demonstrated spin filtering behavior in
+La0.7Sr0.3MnO3/chromite/Fe3O4 junctions without nonmagnetic spacer layers where
+the interface anisotropy plays a significant role in determining transport
+behavior. Detailed studies of chemical and magnetic structure at the interfaces
+indicate that abrupt changes in magnetic anisotropy across the
+non-isostructural interface is the cause of the significant suppression of
+junction magnetoresistance in junctions with MnCr2O4 barrier layers.",1102.4978v1
+2011-05-10,Multiferroic behavior in the new double-perovskite Lu$_2$MnCoO$_6$,"We present a new member of the multiferroic oxides, Lu$_2$MnCoO$_6$, which we
+have investigated using X-ray diffraction, neutron diffraction, specific heat,
+magnetization, electric polarization, and dielectric constant measurements.
+This material possesses an electric polarization strongly coupled to a net
+magnetization below 35 K, despite the antiferromagnetic ordering of the $S =
+3/2$ Mn$^{4+}$ and Co$^{2+}$ spins in an $\uparrow \uparrow \downarrow
+\downarrow$ configuration along the c-direction. We discuss the magnetic order
+in terms of a condensation of domain boundaries between $\uparrow \uparrow$ and
+$\downarrow \downarrow$ ferromagnetic domains, with each domain boundary
+producing a net electric polarization due to spatial inversion symmetry
+breaking. In an applied magnetic field the domain boundaries slide, controlling
+the size of the net magnetization, electric polarization, and magnetoelectric
+coupling.",1105.2058v1
+2012-07-13,Magneto-absorption spectra of hydrogen-like yellow exciton series in cuprous oxide: excitons in strong magnetic fields,"We study the absorption spectra of the yellow excitons in Cu$_2$O in high
+magnetic fields using polarization-resolved optical absorption measurements
+with a high frequency resolution. We show that the symmetry of the yellow
+exciton results in unusual selection rules for the optical absorption of
+polarized light and that the mixing of ortho- and para- excitons in magnetic
+field is important. Our calculation of the energies of the yellow exciton
+series in an arbitrary magnetic field gives an excellent fit to experimental
+data and allows us to understand the complex structure of excitonic levels and
+their magnetic field dependence, which resolves the old-standing disagreement
+between the results of optical absorption and cyclotron resonance measurements.",1207.3372v1
+2012-08-17,Interface induced perpendicular magnetic anisotropy in Co/CoO/Co thin film structure: An in-situ MOKE investigation,"Co /CoO/Co polycrystalline film was grown on Si (001) substrate and magnetic
+properties have been investigated using in-situ magneto-optic Kerr effect
+during growth of the sample. Magnetic anisotropy with easy axis perpendicular
+to the film surface has been observed in top Co layer, whereas bottom layer was
+found to be soft with in-plane magnetization without any influence of top
+layer. Ex-situ in-plane and out-of-plane diffraction measurements revealed that
+the growth of Co on oxidized interface takes place with preferential
+orientation of c-axis perpendicular to the film plane, which results in the
+observed perpendicular magnetic anisotropy. Texturing of the c-axis is expected
+to be a result of minimization of the interface energy due to hybridization
+between Co and oxygen at the interface.",1208.3673v1
+2012-10-18,Measurement of Magnetic Exchange in Ferromagnet-Superconductor La2/3Ca1/3MnO3/YBa2Cu3O7 Bilayers,"The existence of coherent magnetic correlations in the normal phase of
+cuprate high-temperature superconductors has proven difficult to measure
+directly. Here we report on a study of ferromagnetic-superconductor bilayers of
+La2/3Ca1/3MnO3/YBa2Cu3O7 (LCMO/YBCO) with varying YBCO layer thicknesses. Using
+x-ray magnetic circular dichroism, we demonstrate that the ferromagnetic layer
+induces a Cu magnetic moment in the adjacent high-temperature superconductor.
+For thin samples, this moment exists at all temperatures below the Curie
+temperature of the LCMO layer. However, for a YBCO layer thicker than 12 unit
+cells, the Cu moment is suppressed for temperatures above the superconducting
+transition, suggesting this to be a direct measurement of magnetic coherence in
+the normal state of a superconducting oxide.",1210.5049v1
+2013-02-11,Quantum-Confinement-Induced Magnetism in LaNiO$_3$-LaMnO$_3$ Superlattices,"The emergence of magnetic reconstructions at the interfaces of oxide
+heterostructures are often explained via subtle modifications in the electronic
+densities, exchange couplings, or strain. Here an additional possible route for
+induced magnetism is studied in the context of the
+(LaNiO$_3$)$_n$/(LaMnO$_3$)$_n$ superlattices using a hybrid tight-binding
+model. In the LaNiO$_3$ region, the induced magnetizations decouple from the
+intensity of charge leakage from Mn to Ni, but originate from the spin-filtered
+quantum confinement present in these nanostructures. In general, the induced
+magnetization is the largest for the (111)-stacking and the weakest for the
+(001)-stacking superlattices, results compatible with the exchange bias effects
+reported by Gibert et al. Nat. Mater. 11, 195 (2012).",1302.3253v2
+2013-02-27,When metal organic frameworks turn into linear magnets,"We investigate the existence of linear magnetism in the metal organic
+framework materials MOF-74-Fe, MOF-74-Co, and MOF-74-Ni, using first-principles
+density functional theory. MOF-74 displays regular quasi-linear chains of
+open-shell transition metal atoms, which are well separated. Our results show
+that within these chains-for all three materials-ferromagnetic coupling of
+significant strength occurs. In addition, the coupling in-between chains is at
+least one order of magnitude smaller, making these materials almost perfect 1D
+magnets at low temperature. The inter-chain coupling is found to be
+anti-ferromagnetic, in agreement with experiments. While some quasi-1D
+materials exist that exhibit linear magnetism-mostly complex oxides, polymers,
+and a few other rare material-they are typically very difficult to synthesize.
+The significance of our finding is that MOF-74 is very easy to synthesize and
+it is likely the simplest realization of the 1D Ising model in nature. MOF-74
+could thus be used in future experiments to study 1D magnetism at low
+temperature.",1302.6886v1
+2013-03-14,Thermal Stability and Electrical Control of Magnetization of Heusler/Oxide Interface and Non-collinear Spin Transport of Its Junction,"Towards next-generation spintronics devices, such as computer memories and
+logic chips, it is necessary to satisfy high thermal stability, low-power
+consumption and high spin-polarization simultaneously. Here, from
+first-principles, we investigate thermal stability (both structure and
+magnetization) and the electric field control of magnetic anisotropy on Co2FeAl
+(CFA)/MgO. A phase diagram of structural thermal stability of the CFA/MgO
+interface is illustrated. An interfacial perpendicular-anisotropy, coming from
+the Fe-O orbital hybridization, provides high magnetic thermal stability and a
+low stray field. We find an electric-field-induced giant modification of such
+perpendicular-anisotropy via a great magnetoelectric effect (the anisotropy
+energy coefficient beta~10-7 erg/V cm). Our spin electronic-structure and
+non-collinear transport calculations indicate high spin-polarized interfacial
+states and good magnetoresistance properties of CFA/MgO/CFA perpendicular
+magnetic tunnel junctions.",1303.3473v2
+2013-06-17,MnSb2O6: A polar magnet with a chiral crystal structure,"Structural and magnetic chiralities are found to coexist in a small group of
+materials in which they produce intriguing phenomenologies such as the recently
+discovered skyrmion phases. Here, we describe a previously unknown
+manifestation of this interplay in MnSb2O6, a trigonal oxide with a chiral
+crystal structure. Unlike all other known cases, the MnSb2O6 magnetic structure
+is based on co-rotating cycloids rather than helices. The coupling to the
+structural chirality is provided by a magnetic axial vector, related to the
+so-called vector chirality. We show that this unique arrangement is the
+magnetic ground state of the symmetric-exchange Hamiltonian, based on ab-initio
+theoretical calculations of the Heisenberg exchange interactions, and is
+stabilised by out-of-plane anisotropy. MnSb2O6 is predicted to be multiferroic
+with a unique ferroelectric switching mechanism.",1306.3854v1
+2014-01-15,Chiral magnetization textures stabilized by the Dzyaloshinskii-Moriya interaction during spin-orbit torque switching,"We study the effect of the Dzyaloshinskii-Moriya interaction (DMI) on
+current-induced magnetic switching of a perpendicularly magnetized
+heavy-metal/ferromagnet/oxide trilayer both experimentally and through
+micromagnetic simulations. We report the generation of stable helical
+magnetization stripes for a sufficiently large DMI strength in the switching
+region, giving rise to intermediate states in the magnetization confirming the
+essential role of the DMI on switching processes. We compare the simulation and
+experimental results to a macrospin model, showing the need for a micromagnetic
+approach. The influence of the temperature on the switching is also discussed.",1401.3526v2
+2014-07-30,Synthetic magnetoelectric coupling in a nanocomposite multiferroic,"Given the paucity of single phase multiferroic materials (with large
+ferromagnetic moment), composite systems seem an attractive solution in the
+quest to realize magnetoelectric cou-pling between ferromagnetic and
+ferroelectric order parameters. Despite having antiferro-magnetic order, BiFeO3
+(BFO) has nevertheless been a key material in this quest due to excel-lent
+ferroelectric properties at room temperature. We studied a superlattice
+composed of 8 repetitions of 6 unit cells of La0.7Sr0.3MnO3 (LSMO) grown on 5
+unit cells of BFO. Significant net uncompensated magnetization in BFO is
+demonstrated using polarized neutron reflectometry in an insulating
+superlattice. Remarkably, the magnetization enables magnetic field to change
+the dielectric properties of the superlattice, which we cite as an example of
+synthetic magnetoelectric coupling. Importantly, this controlled creation of
+magnetic moment in BFO suggests a much needed path forward for the design and
+implementation of integrated oxide devices for next generation magnetoelectric
+data storage platforms.",1407.8157v2
+2014-10-23,Magnetic structure determination from the magnetic pair distribution function (mPDF): ground state of MnO,"An experimental determination of the magnetic pair distribution function
+(mPDF) defined in an earlier paper (Frandsen, Yang, and Billinge. (2014) Acta
+Crystallogr. A, 70(1), 3-11) is presented for the first time. The mPDF was
+determined from neutron powder diffraction data from a reactor and a neutron
+time-of-flight total scattering source on a powder sample of the
+antiferromagnetic oxide MnO. A description of the data treatment that allowed
+the measured mPDF to be extracted and then modelled is provided and utilized to
+investigate the low-temperature structure of MnO. Atomic and magnetic
+co-refinements support the scenario of a locally monoclinic ground-state atomic
+structure, despite the average structure being rhombohedral, with the magnetic
+PDF analysis successfully recovering the known antiferromagnetic spin
+configuration. The total scattering data suggest a preference for the spin axis
+to lie along the pseudocubic [10$\bar{1}$] direction. Finally, $r$-dependent
+PDF refinements indicate that the local monoclinic structure tends toward the
+average rhombohedral $R\overline{3}m$ symmetry over a length scale of
+approximately 100~\AA.",1410.6377v2
+2014-10-27,Hysteretic Magnetotransport in SmB6 at Low Magnetic Fields,"Utilizing Corbino disc structures, we have examined the magnetic field
+response of resistivity for the surface states of SmB6 on different crystalline
+surfaces at low temperatures. Our results reveal a hysteretic behavior whose
+magnitude depends on the magnetic field sweep rate and temperature. Although
+this feature becomes smaller when the field sweep is slower, a complete
+elimination or saturation is not observed in our slowest sweep-rate
+measurements, which is much slower than a typical magnetotransport trace. These
+observations cannot be explained by quantum interference corrections such as
+weak anti-localization. Instead, they are consistent with behaviors of glassy
+surface magnetic ordering, whose magnetic origin is most likely from samarium
+oxide (Sm2O3) forming on the surface during exposure to ambient conditions.",1410.7430v1
+2015-01-08,X-ray magnetic circular dichroism study of epitaxial magnetite ultrathin film on MgO (100),"The spin and orbital magnetic moments of the Fe3O4 epitaxial ultrathin film
+synthesized by plasma assisted simultaneous oxidization on MgO(100) have been
+studied with X-ray magnetic circular dichroism (XMCD). The ultrathin film
+retains a rather large total magnetic moment, i.e. (2.7+-0.15) uB/f.u., which
+is ~ 70% of that for the bulk-like Fe3O4. A significant unquenched orbital
+moment up to (0.54+-0.05) uB/f.u. was observed, which could come from the
+symmetry breaking at the Fe3O4/MgO interface. Such sizable orbital moment will
+add capacities to the Fe3O4-based spintronics devices in the magnetization
+reversal by the electric field.",1501.01803v3
+2015-02-20,"Preparation, structural and magnetic studies on BiFe1-xCrxO3 (x=0.0, 0.05 and 0.1) multiferroic nanoparticles","BiFe1-xCrxO3 (x=0.0, 0.05 and 0.1) nanoparticles are prepared by a combustion
+method without using any solvent. All the synthesized nanoparticles are single
+phase in nature, nearly spherical in shape and crystallize in distorted
+perovskite structure and space group R3c with an average crystallite size of
+the order of 40 nm. The room temperature magnetization observed in BiFeO3
+nanoparticles is larger than that in the bulk. Increasing Cr doping leads to
+increase in the magnetization and coercivity. Strong superexchange interaction
+between Fe3+ and Cr3+ atoms is likely to give rise to such increase in
+magnetization with Cr-doping. M\""ossbauer data of these nanoparticles show
+ordered magnetic state in which Fe atoms are in 3+ oxidation states.",1502.05921v1
+2015-03-12,A single crystal Co2+ fluoride pyrochlore antiferromagnet,"We report the crystal growth, crystal structure and basic magnetic properties
+of a new cobalt-based pyrochlore, NaSrCo$_2$F$_7$. Na and Sr are completely
+disordered on the non-magnetic large atom A sites, while magnetic S=3/2
+Co$^{2+}$ fully occupies the pyrochlore lattice B sites. This system exhibits
+an isotropic magnetic susceptibility with strong antiferromagnetic interactions
+(${\theta}_{CW}$ = -127(1)), a large effective moment (${\rho_{eff}}$ = 5.9(1)
+${\mu_B}$/Co) and no spin freezing until 3 K. Thus NaSrCo$_2$F$_7$ is a
+geometrically frustrated antiferromagnet with a frustration index f =
+-${\theta_{CW}}$/T$_f$ = 42. AC susceptibility, DC susceptibility, and heat
+capacity are utilized to characterize the spin freezing at low temperatures. We
+propose that NaSrCo$_2$F$_7$, compared here to the related material
+NaCaCo$_2$F$_7$, may be the realization of a frustrated pyrochlore
+antiferromagnet with weak bond disorder. The strong magnetic frustration at an
+easily accessible temperature and the availability of large single crystals
+make this one of the potentially interesting alternatives to the more commonly
+studied rare earth oxide pyrochlores.",1503.03751v1
+2015-04-07,Evolution of Magnetism in Single-Crystal Ca2Ru1-xIrxO4 (0< x <0.65),"We report structural, magnetic, transport and thermal properties of
+single-crystal Ca2Ru1-xIrxO4 (0 < x< 0.65). Ca2RuO4 is a structurally-driven
+Mott insulator with a metal-insulator transition at TMI = 357 K, which is well
+separated from antiferromagnetic order at TN = 110 K. Substitution of 5d
+element, Ir, for Ru enhances spin-orbit coupling (SOC) and locking between the
+structural distortions and magnetic moment canting. In particular, Ir doping
+intensifies the distortion or rotation of Ru/IrO6 octahedra and induces weak
+ferromagnetic behavior along the c-axis. Moreover, the magnetic ordering
+temperature TN increases from 110 K at x = 0 to 215 K with enhanced magnetic
+anisotropy at x = 0.65. The effect of Ir doping sharply contrasts with that of
+3d-element doping such as Cr, Mn and Fe, which suppresses TN and induces
+unusual negative volume thermal expansion. The stark difference between 3d- and
+5d-element doping underlines a strong magnetoelastic coupling inherent in the
+Ir-rich oxides.",1504.01750v1
+2015-04-27,Magnetic fluctuations driven insulator-to-metal transition in Ca(Ir$_{1-x}$Ru$_{x}$)O$_{3}$,"Magnetic fluctuations in transition metal oxides are a subject of intensive
+research because of the key role they are expected to play in the transition
+from the Mott insulator to the unconventional metallic phase of these
+materials, and also as drivers of superconductivity. Despite much effort, a
+clear link between magnetic fluctuations and the insulator-to-metal transition
+has not yet been established. Here we report the discovery of a compelling link
+between magnetic fluctuations and the insulator-to-metal transition in
+Ca(Ir$_{1-x}$Ru$_{x}$)O$_{3}$ perovskites as a function of the doping
+coefficient x. We show that when the material turns from insulator to metal, at
+a critical value of x$\sim$ 0.3, magnetic fluctuations change their character
+from antiferromagnetic, a Mott insulator phase, to ferromagnetic, an itinerant
+electron state with Hund's orbital coupling. These results are expected to have
+wide-ranging implications for our understanding of the unconventional
+properties of strongly correlated electrons systems",1504.06901v1
+2015-06-09,"Synthesis, Crystal Structure and Magnetism of Eu3Sc2O5Fe2As2","The iron arsenide Eu3Fe2O5Fe2As2 was synthesized at 1173-1373 K in a
+resistance furnace and characterized by X-ray powder diffraction with Rietveld
+analysis: Sr3Fe2O5Cu2S2-type, I4/mmm, a = 406.40(1) pm, c = 2646.9(1) pm.
+Layers of edge-sharing FeAs4/4 tetrahedra are separated by perovskite-like
+oxide blocks. No structural transition occurs in the temperature range from 10
+to 300 K. Magnetic measurements have revealed Curie-Weiss behavior with an
+effective magnetic moment of 7.79 muB per europium atom in agreement with the
+theoretical value of 7.94 muB for Eu2+. A drop in the magnetic susceptibility
+at 5 K indicates possible antiferromagnetic ordering. 151Eu and 57Fe
+M\""ossbauer spectroscopic measurements have confirmed a beginning cooperative
+magnetic phenomenon by showing significantly broadened spectra at 4.8 K
+compared to those at 78 K.",1506.02925v1
+2015-08-07,Magnetic and spectral properties of multi-sublattice oxides SrY2O4:Er3+ and SrEr2O4,"SrEr2O4 is a geometrically frustrated magnet which demonstrates rather
+unusual properties at low temperatures including a coexistence of long- and
+short-range magnetic order, characterized by two different propagation vectors.
+In the present work, the effects of crystal fields (CF) in this compound
+containing four magnetically inequivalent erbium sublattices are investigated
+experimentally and theoretically. We combine the measurements of the CF levels
+of the Er3+ ions made on a powder sample of SrEr2O4 using neutron spectroscopy
+with site-selective optical and electron paramagnetic resonance measurements
+performed on single crystal samples of the lightly Er-doped nonmagnetic
+analogue, SrY2O4. Two sets of CF parameters corresponding to the Er3+ ions at
+the crystallographically inequivalent lattice sites are derived which fit all
+the available experimental data well, including the magnetization and dc
+susceptibility data for both lightly doped and concentrated samples.",1508.01638v1
+2015-08-12,Ferroelectricity driven magnetism at domain walls in LaAlO$_3$/PbTiO$_3$ superlattices,"Charge dipole moment and spin moment rarely coexist in single-phase bulk
+materials except in some multiferroics. Despite the progress in the past
+decade, for most multiferroics their magnetoelectric performance remains poor
+due to the intrinsic exclusion between charge dipole and spin moment. As an
+alternative approach, the oxide heterostructures may evade the intrinsic limits
+in bulk materials and provide more attractive potential to realize the
+magnetoelectric functions. Here we perform a first-principles study on
+LaAlO$_3$/PbTiO$_3$ superlattices. Although neither of the components is
+magnetic, magnetic moments emerge at the ferroelectric domain walls of
+PbTiO$_3$ in these superlattices. Such a twist between ferroelectric domain and
+local magnetic moment, not only manifests an interesting type of
+multiferroicity, but also is possible useful to pursuit the electrical-control
+of magnetism in nanoscale heterostructures.",1508.02889v1
+2016-03-11,Atomic-scale control of magnetic anisotropy via novel spin-orbit coupling effect in La2/3Sr1/3MnO3/SrIrO3 superlattices,"Magnetic anisotropy (MA) is one of the most important material properties for
+modern spintronic devices. Conventional manipulation of the intrinsic MA, i.e.
+magnetocrystalline anisotropy (MCA), typically depends upon crystal symmetry.
+Extrinsic control over the MA is usually achieved by introducing shape
+anisotropy or exchange bias from another magnetically ordered material. Here we
+demonstrate a pathway to manipulate MA of 3d transition metal oxides (TMOs) by
+digitally inserting non-magnetic 5d TMOs with pronounced spin-orbit coupling
+(SOC). High quality superlattices comprised of ferromagnetic La2/3Sr1/3MnO3
+(LSMO) and paramagnetic SrIrO3 (SIO) are synthesized with the precise control
+of thickness at atomic scale. Magnetic easy axis reorientation is observed by
+controlling the dimensionality of SIO, mediated through the emergence of a
+novel spin-orbit state within the nominally paramagnetic SIO.",1603.03794v2
+2016-06-14,Chiral Ordering Spin Associated Glass like State in SrRuO3SrIrO3 Superlattice,"Heterostructure interface provides a powerful platform to observe rich
+emergent phenomena, such as interfacial superconductivity, nontrivial
+topological surface state. Here SrRuO3/SrIrO3 superlattices were epitaxially
+synthesized. The magnetic and electrical properties of these superlattices were
+characterized. Broad cusps in the zero field cooling magnetization curves and
+near stable residual magnetization below the broad cusps, as well as two steps
+magnetization hysteresis loops are observed. The magnetization relaxes
+following a modified Stretched function model indicating coexistence of spin
+glass and ferromagnetic ordering in the superlattices. Topological Hall effect
+was demonstrated at low temperature and weakened with the increase of SrIrO3
+layer thickness. These results suggest that chiral ordering spin texture were
+generated at the interfaces due to the interfacial Dzyaloshinskii-Moriya (DM)
+interaction, which generates the spin glass behaviors. The present work
+demonstrates that SrIrO3 can effectively induce interface DM interactions in
+heterostructures, it would pave light on the new research directions of strong
+spin orbit interaction oxides, from the viewpoints of both basic science and
+prospective spintronics devices applications.",1606.04313v2
+2016-09-29,Proposal for a Leaky-Integrate-Fire Spiking Neuron based on Magneto-Electric Switching of Ferro-magnets,"The efficiency of the human brain in performing classification tasks has
+attracted considerable research interest in brain-inspired neuromorphic
+computing. Hardware implementations of a neuromorphic system aims to mimic the
+computations in the brain through interconnection of neurons and synaptic
+weights. A leaky-integrate-fire (LIF) spiking model is widely used to emulate
+the dynamics of neuronal action potentials. In this work, we propose a spin
+based LIF spiking neuron using the magneto-electric (ME) switching of
+ferro-magnets. The voltage across the ME oxide exhibits a typical
+leaky-integrate behavior, which in turn switches an underlying ferro-magnet.
+Due to the effect of thermal noise, the ferro-magnet exhibits probabilistic
+switching dynamics, which is reminiscent of the stochasticity exhibited by
+biological neurons. The energy-efficiency of the ME switching mechanism coupled
+with the intrinsic non-volatility of ferro-magnets result in lower energy
+consumption, when compared to a CMOS LIF neuron. A device to system-level
+simulation framework has been developed to investigate the feasibility of the
+proposed LIF neuron for a hand-written digit recognition problem",1609.09158v1
+2018-02-14,Collective Coordinate Models of Domain Wall Motion in Perpendicularly Magnetized Systems under the Spin Hall Effect and Longitudinal Fields,"Recent studies on heterostructures of ultrathin ferromagnets sandwiched
+between a heavy metal layer and an oxide have highlighted the importance of
+spin-orbit coupling (SOC) and broken inversion symmetry in domain wall (DW)
+motion. Specifically, chiral DWs are stabilized in these systems due to the
+Dzyaloshinskii-Moriya interaction (DMI). SOC can also lead to enhanced current
+induced DW motion, with the spin Hall effect (SHE) suggested as the dominant
+mechanism for this observation. The efficiency of SHE driven DW motion depends
+on the internal magnetic structure of the DW, which could be controlled using
+externally applied longitudinal in-plane fields. In this work, micromagnetic
+simulations and collective coordinate models are used to study current-driven
+DW motion under longitudinal in-plane fields in perpendicularly magnetized
+samples with strong DMI. Several extended collective coordinate models are
+developed to reproduce the micromagnetic results. While these extended models
+show improvements over traditional models of this kind, there are still
+discrepancies between them and micromagnetic simulations which require further
+work.",1802.04917v1
+2018-04-02,Gapped ground state in the zigzag pseudospin-1/2 quantum antiferromagnetic chain compound PrTiNbO6,"We report a single-crystal study on the magnetism of the rare-earth compound
+PrTiNbO$_6$ that experimentally realizes the zigzag pseudospin-$\frac{1}{2}$
+quantum antiferromagnetic chain model. Random crystal electric field caused by
+the site mixing between non-magnetic Ti$^{4+}$ and Nb$^{5+}$, results in the
+non-Kramers ground state quasi-doublet of Pr$^{3+}$ with the effective
+pseudospin-$\frac{1}{2}$ Ising moment. Despite the antiferromagnetic intersite
+coupling of about 4 K, no magnetic freezing is detected down to 0.1 K, whilst
+the system approaches its ground state with almost zero residual spin entropy.
+At low temperatures, a sizable gap of about 1 K is observed in zero field. We
+ascribe this gap to off-diagonal anisotropy terms in the pseudospin
+Hamiltonian, and argue that rare-earth oxides open an interesting venue for
+studying magnetism of quantum spin chains.",1804.00687v1
+2018-11-03,Ferromagnetic resonance in the complex permeability of an Fe$_3$O$_4$ nanosuspension at radio and microwave frequencies,"The complex permeability of an iron-oxide nanosuspension has been measured as
+a function of magnetic field strength at RF and microwave frequencies using a
+loop-gap resonator. The particles were suspended in water and had an 8-nm
+diameter Fe$_3$O$_4$ core that was coated by Dextran. The real part of the
+permeability increased sharply beyond a frequency-dependent threshold value of
+the static magnetic field before saturating. Just beyond this threshold field,
+there was a peak in the imaginary part of the permeability. The permeability
+measurements, which exhibited features associated with ferromagnetic resonance,
+were used to determine the dependence of the microwave absorption on static
+magnetic field strength. Using the absorption data, the $g$-factor of the
+nanosuspension was found to be $1.86\pm 0.07$.",1811.01168v1
+2019-05-28,Emergent magnetic state in (111)-oriented quasi-two-dimensional spinel oxides,"We report on the emergent magnetic state of (111)-oriented CoCr2O4 ultrathin
+films sandwiched by Al2O3 in the quantum confined geometry. At the
+two-dimensional crossover, polarized neutron reflectometry reveals an anomalous
+enhancement of the total magnetization compared to the bulk value. Synchrotron
+x-ray magnetic circular dichroism (XMCD) demonstrates the appearance of
+long-range ferromagnetic ordering of spins on both Co and Cr sublattices.
+Brillouin function analyses further corroborates that the observed phenomena
+are due to the strongly altered magnetic frustration, manifested by the onset
+of a Yafet-Kittel type ordering as the new ground state in the ultrathin limit,
+which is unattainable in the bulk.",1905.12024v1
+2016-11-02,DFT modelling of the effect of strong magnetic field on Aniline molecule,"Aniline is an organic compound with the stoichiometric expression
+$C_{6}H_{5}NH_{2}$; consisting of a phenyl structure attached to an amino
+group. It is colorless, but it slowly oxidizes and resinifies in air, giving a
+red-brown tint to aged samples. Until now, there are only few researches on
+Aniline considering low magnetic fields. In this work, we study Aniline
+molecule under different high magnetic fields using density functional theory
+methods including independent particle and interacting particle approaches. We
+obtain charge density distrubitions, energy dispersions, dipol moments and
+forces as functions of position and magnetic field. Our numerical results show
+that magnetic field affects electron density of the considered molecule. As a
+result, it is observed that there are strong fluctuations in energy dispersion.",1611.00552v1
+2017-04-26,Transfer of magnetic order and anisotropy through epitaxial integration of 3$d$ and 4$f$ spin systems,"Resonant x-ray scattering at the Dy $M_5$ and Ni $L_3$ absorption edges was
+used to probe the temperature and magnetic field dependence of magnetic order
+in epitaxial LaNiO$_3$-DyScO$_3$ superlattices. For superlattices with 2 unit
+cell thick LaNiO$_3$ layers, a commensurate spiral state develops in the Ni
+spin system below 100 K. Upon cooling below $T_{ind} = 18$ K, Dy-Ni exchange
+interactions across the LaNiO$_3$-DyScO$_3$ interfaces induce collinear
+magnetic order of interfacial Dy moments as well as a reorientation of the Ni
+spins to a direction dictated by the strong magneto-crystalline anisotropy of
+Dy. This transition is reversible by an external magnetic field of 3 T.
+Tailored exchange interactions between rare-earth and transition-metal ions
+thus open up new perspectives for the manipulation of spin structures in
+metal-oxide heterostructures and devices.",1704.07967v1
+2012-01-11,Neutron scattering studies on stripe phases in non-cuprate materials,"Several non-cuprates layered transition-metal oxides exhibit clear evidence
+for stripe ordering of charges and magnetic moments. Therefore, stripe order
+should be considered as the typical consequence of doping a Mott insulator, but
+only in cuprates stripe order or fluctuating stripes coexist with metallic
+properties. A linear relationship between the charge concentration and the
+incommensurate structural and magnetic modulations can be considered as the
+finger print of stripe ordering with localized degrees of freedom. In
+nickelates and in cobaltates with K2NiF4 structure, doping suppresses the
+nearest-neighbor antiferromagnetism and induces stripe order. The higher amount
+of doping needed to induce stripe phases in these non-cuprates series can be
+attributed to reduced charge mobility. Also manganites exhibit clear evidence
+for stripe phases with further enhanced complexity, because orbital degrees of
+freedom are involved. Orbital ordering is the key element of stripe order in
+manganites since it is associated with the strongest structural distortion and
+with the perfectly fulfilled relation between doping and incommensurability.
+Magnetic excitations in insulating stripe phases exhibit strong similarity with
+those in the cuprates, but only for sufficiently short magnetic correlation
+lengths reflecting well-defined magnetic stripes that are only loosely coupled.",1201.2356v1
+2014-06-16,An air-cooled Litz wire coil for measuring the high frequency hysteresis loops of magnetic samples : a useful setup for magnetic hyperthermia applications,"A low-cost and simple setup for measuring the high-frequency hysteresis loops
+of magnetic samples is described. An AMF in the range 6-100 kHz with amplitude
+up to 80 mT is produced by a Litz wire coil. The latter is air-cooled using a
+forced-air approach so no water flow is required to run the setup.
+High-frequency hysteresis loops are measured using a system of pick-up coils
+and numerical integration of signals. Reproducible measurements are obtained in
+the frequency range of 6-56 kHz. Measurement examples on ferrite cylinders and
+on iron oxide nanoparticle ferrofluids are shown. Comparison with other
+measurement methods of the hysteresis loop area (complex susceptibility,
+quasi-static hysteresis loops and calorific measurements) is provided and shows
+the coherency of the results obtained with this setup. This setup is well
+adapted to the magnetic characterization of colloidal solutions of MNPs for
+magnetic hyperthermia applications.",1406.4013v1
+2016-08-26,Magnetic properties of the honeycomb oxide Na$_2$Co$_2$TeO$_6$,"We have studied the magnetic properties of Na$_2$Co$_2$TeO$_6$, which
+features a honeycomb lattice of magnetic Co$^{2+}$ ions, through macroscopic
+characterization and neutron diffraction on a powder sample. We have shown that
+this material orders in a zig-zag antiferromagnetic structure. In addition to
+allowing a linear magnetoelectric coupling, this magnetic arrangement displays
+very peculiar spatial magnetic correlations, larger in the honeycomb planes
+than between the planes, which do not evolve with the temperature. We have
+investigated this behavior by Monte Carlo calculations using the
+$J_1$-$J_2$-$J_3$ model on a honeycomb lattice with a small interplane
+interaction. Our model reproduces the experimental neutron structure factor,
+although its absence of temperature evolution must be due to additional
+ingredients, such as chemical disorder or quantum fluctuations enhanced by the
+proximity to a phase boundary.",1608.07593v2
+2017-10-20,Confinement of magnetism in atomically-thin $La_{0.7}Sr_{0.3}CrO_3$/$La_{0.7}Sr_{0.3}MnO_3$ heterostructures,"At crystalline interfaces where a valence mismatch exists, electronic and
+structural interactions may occur to relieve the polar mismatch leading to the
+stabilization of non-bulklike phases. We show that spontaneous reconstructions
+at polar $La_{0.7}Sr_{0.3}MnO_3$ interfaces are correlated with suppressed
+ferromagnetism for film thicknesses on the order of a unit cell. We investigate
+the structural and magnetic properties of valence-matched
+$La_{0.7}Sr_{0.3}CrO_3$ - $La_{0.7}Sr_{0.3}MnO_3$ interfaces using a
+combination of high-resolution electron microscopy, first principles theory,
+synchrotron X-ray scattering and magnetic spectroscopy and
+temperature-dependent magnetometry. A combination of an antiferromagnetic
+coupling between the $La_{0.7}Sr_{0.3}CrO_3$ and $La_{0.7}Sr_{0.3}MnO_3$ layers
+and a suppression of interfacial polar distortions are found to result in
+robust long range ferromagnetic ordering for ultra-thin
+$La_{0.7}Sr_{0.3}MnO_3$. These results underscore the critical importance of
+interfacial structural and magnetic interactions in the design of devices based
+on two-dimensional oxide magnetic systems.",1710.07592v2
+2017-12-04,Surface magnetism of gallium arsenide nanofilms,"Gallium arsenide (GaAs) is the widest used second generation semiconductor
+with a direct band gap and increasingly used as nanofilms. However, the
+magnetic properties of GaAs nanofilms have never been studied. Here we find by
+comprehensive density functional theory calculations that GaAs nanofilms
+cleaved along the <111> and <100> directions become intrinsically metallic
+films with strong surface magnetism and magnetoelectric (ME) effect. The
+surface magnetism and electrical conductivity are realized via a combined
+effect of transferring charge induced by spontaneous electric-polarization
+through the film thickness and spin-polarized surface states. The surface
+magnetism of <111> nanofilms can be significantly and linearly tuned by
+vertically applied electric field, endowing the nanofilms unexpectedly high ME
+coefficients, which are tens of times higher than those of ferromagnetic metals
+and transition metal oxides.",1712.00990v1
+2019-06-18,Discovery of room temperature ferromagnetism in metal-free organic semiconductors,"Creating magnetic semiconductors that work at warm circumstance is still a
+great challenge in the physical sciences. Here, we report the discovery of
+ferromagnetism in the metal-free perylene diimide semiconductor, whose Curie
+temperature is higher than 400 Kelvin. A solvothermal approach is used to
+reduce and dissolve the rigid-backbone perylene diimide crystallites, and
+radical anion aggregates were fabricated by the subsequent self-assembly and
+oxidation process. Magnetic measurements exhibit the ferromagnetic ordering
+with the saturated magnetization of 0.48 $\mu_{\rm B}$ per molecule and the
+appreciable magnetic anisotropy. X-ray magnetic circular dichroism spectra
+suggest the ferromagnetism stems from $\pi$ orbitals of radicals. Our findings
+unambitiously demonstrate the long-range ferromagnetic ordering can survive at
+room temperature in organic semiconductors, although which are intuitively
+regarded to be nonmagnetic.",1906.07531v2
+2019-07-05,Supraferromagnetic correlations in clusters of magnetic nanoflowers,"Magnetic nanoflowers are densely packed aggregates of superferromagnetically
+coupled iron oxide nanocrystallites, which excel during magnetic hyperthermia
+experiments. Here, we investigate the nature of the moment coupling within a
+powder of such nanoflowers using spin-resolved small-angle neutron scattering.
+Within the powder the nanoparticles are agglomerated to clusters, and we can
+show that the moments of neighboring nanoflowers tend to align parallel to each
+other. Thus, the whole system resembles a hierarchical magnetic nanostructure
+consisting of three distinct levels, i.e. (i) the ferrimagnetic
+nanocrystallites as building blocks, (ii) the superferromagnetic nanoflowers,
+and (iii) the \textit{supra}ferromagnetic clusters of nanoflowers. We surmise
+that such a supraferromagnetic coupling explains the enhanced magnetic
+hyperthermia performance in case of interacting nanoflowers.",1907.02752v2
+2019-09-30,Highly frustrated magnetism in relativistic $\boldsymbol{d}^\mathbf{4}$ Mott insulators: Bosonic analog of Kitaev honeycomb model,"We study the orbitally frustrated singlet-triplet models that emerge in the
+context of spin-orbit coupled Mott insulators with $t_{2g}^4$ electronic
+configuration. In these compounds, low-energy magnetic degrees of freedom can
+be cast in terms of three-flavor ""triplon"" operators describing the transitions
+between spin-orbit entangled $J=0$ ionic ground state and excited $J=1$ levels.
+In contrast to a conventional, flavor-isotropic O(3) singlet-triplet models,
+spin-orbit entangled triplon interactions are flavor-and-bond selective and
+thus highly frustrated. In a honeycomb lattice, we find close analogies with
+the Kitaev spin model -- an infinite number of conserved quantities, no
+magnetic condensation, and spin correlations being strictly short-ranged.
+However, due to the bosonic nature of triplons, there are no emergent gapless
+excitations within the spin gap, and ground state is a strongly correlated
+paramagnet of dense triplon pairs with no long-range entanglement. Using exact
+diagonalization, we study the bosonic Kitaev model and its various extensions,
+which break exact symmetries of the model and allow magnetic condensation of
+triplons. Possible implications for magnetism of ruthenium oxides are
+discussed.",1910.00074v2
+2019-10-03,Shaping Magnetite Nanoparticles from First-principles,"Iron oxide magnetic nanoparticles (NPs) are stimuli-responsive materials at
+the forefront of nanomedicine. Their realistic finite temperature simulations
+are a formidable challenge for first-principles methods. Here, we use density
+functional tight binding to open up the required time and length scales and
+obtain global minimum structures of Fe3O4 NPs of realistic size (1400 atoms,
+2.5 nm) and of different shapes, which we then refine with hybrid density
+functional theory methods to accomplish proper electronic and magnetic
+properties, which have never been accurately described in simulations. On this
+basis, we develop a general empirical formula and prove its predictive power
+for the evaluation of the total magnetic moment of Fe3O4 NPs. By converting the
+total magnetic moment into the macroscopic saturation magnetization, we
+rationalize the experimentally observed dependence with shape. We also reveal
+interesting reconstruction mechanisms and unexpected patterns of charge
+ordering.",1910.01704v2
+2021-01-22,"Magnetic doping effects on the superconductivity of Y1-xMxBa2Cu3O7-d (M = Fe, Co, Ni)","The discovery of superconductivity in copper oxide compounds has attracted
+considerable attention over the past three decades. The high transition
+temperature in these compounds, exhibiting proximity to an antiferromagnetic
+order in their phase diagrams, remains one of the main areas of research. The
+present study attempts to introduce Fe, Co and Ni magnetic impurities into the
+superconducting Y-123 with the aim of exploring the transition temperature
+behavior. The solid-state synthesis is exploited to prepare fully oxygenated
+Y1-xMxBa2Cu3O7 (M = Co, Fe, Ni) samples with low levels of doping (0< x <
+0.03). Systematic measurements are then employed to assess the synthesized
+samples using AC magnetic susceptibility, electrical resistivity and X-ray
+diffraction. The measurements revealed an increase in Tc as a result of
+magnetic substitution for Y. However, the study of non-magnetic dopings on the
+fully oxygenated Y1-xM'xBa2Cu3O7 (M' = Ca, Sr) samples showed a decrease in Tc.
+Quantitative XRD analysis further suggested that the internal pressure could
+have minor effects on the increase in Tc. The normal state resistivity vs
+temperature showed a linear profile, confirming that the samples are at an
+optimal doping of the carrier concentration.",2101.09292v1
+2017-05-11,"First principles investigations of electronic, magnetic and bonding peculiarities of uranium nitride-fluoride UNF","Based on geometry optimization and magnetic structure investigations within
+density functional theory, unique uranium nitride fluoride UNF, isoelectronic
+with UO2, is shown to present peculiar differentiated physical properties. Such
+specificities versus the oxide are related with the mixed anionic sublattices
+and the layered-like tetragonal structure characterized by covalent like
+[U2N2]2+motifs interlayered by ionic like [F2]2- ones and illustrated herein
+with electron localization function graphs. Particularly the ionocovalent
+chemical picture shows, based on overlap population analyses, stronger U-N
+bonding versus N-F and d(U-N) < d(U-F) distances. Based on LDA+U calculations
+the ground state magnetic structure is insulating antiferromagnet with 2 Bohr
+Magnetons magnetization per magnetic subcell and ~2 eV band gap.",1705.04068v1
+2019-02-08,Magnetization beyond the Ising limit of Ho$_2$Ti$_2$O$_7$,"We report that the local Ising anisotropy in pyrochlore oxides - the crucial
+requirement for realizing the spin-ice state - can be broken by means of high
+magnetic fields. For the case of the well-established classical spin-ice
+compound Ho$_2$Ti$_2$O$_7$ the magnetization exceeds the angle-dependent
+saturation value of the Ising limit using ultra-high fields up to 120 T.
+However, even under such extreme magnetic fields full saturation cannot be
+achieved. Crystal-electric-field calculations reveal that a level crossing for
+two of the four ion positions leads to magnetization steps at 55 and 100 T. In
+addition, we show that by using a field sweep rate in the range of the
+spin-relaxation time the dynamics of the spin system can be probed. Exclusively
+at 25 ns/T a new peak of the susceptibility appears around 2 T. We argue, this
+signals the cross-over between spin-ice and polarized correlations.",1902.02990v1
+2019-02-24,Magnetic Nanoparticle Relaxation Dynamics-based Magnetic Particle Spectroscopy (MPS) for Rapid and Wash-free Molecular Sensing,"Magnetic nanoparticles (MNPs) have been extensively used as contrasts and
+tracers for bioimaging, heating sources for tumor therapy, carriers for
+controlled drug delivery, and labels for magnetic immunoassays. Here, we
+describe a MNP relaxation dynamics-based magnetic particle spectroscopy (MPS)
+method for the quantitative detection of molecular biomarkers. In MPS
+measurements, the harmonics of oscillating MNPs are recorded and used as a
+metric for the freedom of rotational motion, which indicates the bound states
+of the MNPs. These harmonics can be collected from microgram quantities of iron
+oxide nanoparticles within 10 seconds. Using a streptavidin-biotin binding
+system, we demonstrate the feasibility of using MPS to sense these molecular
+interactions, showing this method is able to achieve rapid, wash-free
+bioassays, and is suitable for future point-of-care (POC), sensitive, and
+versatile diagnosis.",1902.08867v2
+2019-03-06,Anomalous Magnetic Behavior in Ba2CoO4 with Isolated CoO4 Tetrahedra,"The dimensionality of the electronic and magnetic structure of a given
+material is generally predetermined by its crystal structure. Here, using
+elastic and inelastic neutron scattering combined with magnetization
+measurements, we find unusual magnetic behavior in three-dimensional (3D)
+Ba2CoO4. In spite of isolated CoO4 tetrahedra, the system exhibits a 3D
+noncollinear antiferromagnetic order in the ground state with an anomalously
+large Curie-Weiss temperature of 110 K compared to TN = 26 K. More
+unexpectedly, spin dynamics displays quasi-2D spin wave dispersion with an
+unusually large spin gap, and 1D magnetoelastic coupling. Our results indicate
+that Ba2CoO4 is a unique system for exploring the interplay between isolated
+polyhedra, low-dimensional magnetism, and novel spin states in oxides.",1903.02490v1
+2021-04-29,High-Dimensional Neural Network Potentials for Magnetic Systems Using Spin-Dependent Atom-Centered Symmetry Functions,"Machine learning potentials have emerged as a powerful tool to extend the
+time and length scales of first principles-quality simulations. Still, most
+machine learning potentials cannot distinguish different electronic spin
+orientations and thus are not applicable to materials in different magnetic
+states. Here, we propose spin-dependent atom-centered symmetry functions as a
+new type of descriptor taking the atomic spin degrees of freedom into account.
+When used as input for a high-dimensional neural network potential (HDNNP),
+accurate potential energy surfaces of multicomponent systems describing
+multiple magnetic states can be constructed. We demonstrate the performance of
+these magnetic HDNNPs for the case of manganese oxide, MnO. We show that the
+method predicts the magnetically distorted rhombohedral structure in excellent
+agreement with density functional theory and experiment. Its efficiency allows
+to determine the N\'{e}el temperature considering structural fluctuations,
+entropic effects, and defects. The method is general and is expected to be
+useful also for other types of systems like oligonuclear transition metal
+complexes.",2104.14439v1
+2021-06-09,Nearly itinerant electronic groundstate in the intercalated honeycomb iridate Ag$_3$LiIr$_2$O$_6$,"We use x-ray spectroscopy at Ir L$_3$/L$_2$ absorption edge to study powder
+samples of the intercalated honeycomb magnet Ag$_3$LiIr$_2$O$_6$. Based on
+x-ray absorption and resonant inelastic x-ray scattering measurements, and
+exact diagonalization calculations including next-neighbour Ir-Ir electron
+hoping integrals, we argue that the intercalation of Ag atoms results in a
+nearly itinerant electronic structure with enhanced Ir-O hybridization. As a
+result of the departure from the local relativistic $j_{\rm eff}\! = \!1/2$
+state, we find that the relative orbital contribution to the magnetic moment is
+increased, and the magnetization density is spatially extended and asymmetric.
+Our results confirm the importance of metal - ligand hybridazation in the
+magnetism of transition metal oxides and provide empirical guidance for
+understanding the collective magnetism in intercalated honeycomb iridates.",2106.05309v1
+2021-07-16,Dependence of band gaps in d-electron perovskite oxides on magnetism,"Understanding the controlling principles of band gaps trends in d electron
+perovskites is needed both for gauging metal-insulator transitions, as well as
+their application in catalysis and doping. The magnitude of this band gap is
+rather different for different magnetic spin configurations. We find via
+electronic structure theory that the factors that connect gapping magnitudes to
+magnetism depend on the nature of the band edge orbital character (BEOC) and
+surprisingly scale with the number of antiferromagnetic contacts z$_i$ between
+neighboring transition metal ions. The dependence is weak when the BEOC are
+(d,d)-like (""Mott insulators""), whereas this dependence is rather strong in
+(p,d)-like (""charge transfer"" insulators). These unexpected rules are traced to
+the reduced orbital interactions through the increase in the number of
+antiferromagnetic contacts between transition metal ions. The impact of
+magnetic order is not limited to the band gap magnitude and includes also the
+magnitude of lattice distortions connected to the electronic structure. These
+results highlight the importance of establishing in electronic structure theory
+of gap-related phenomena (doping, transport, metal-insulator transitions,
+conductive interfaces) the appropriate magnetic order.",2107.07794v1
+2021-11-01,Sr$_3$LiIrO$_6$: a potential quantum spin liquid candidate in the one dimensional $d^4$ iridate family,"Spin-orbit coupling (SOC) offers a large variety of novel and extraordinary
+magnetic and electronic properties in otherwise `ordinary pool' of heavy ion
+oxides. Here we present a detailed study on an apparently isolated hexagonal
+2$H$ spin-chain $d^4$ iridate Sr$_3$LiIrO$_6$ (SLIO) with geometric
+frustration. Our structural studies clearly reveal perfect Li-Ir chemical order
+in this compound. Our combined experimental and {\it ab-initio} electronic
+structure investigations establish a magnetic ground state with finite
+Ir$^{5+}$ magnetic moments in this compound, contrary to the anticipated
+nonmagnetic $J$=0 state. Furthermore, the dc magnetic susceptibility ($\chi$),
+heat capacity ($C_p$) and spin-polarized density functional theory (DFT)
+studies unravel that despite having noticeable antiferromagnetic correlation
+among the Ir$^{5+}$ local moments, this SLIO system evades any kind of magnetic
+ordering down to at least 2 K due to geometrical frustration, arising from the
+comparable interchain Ir-O-O-Ir superexchange interaction strengths, hence
+promoting SLIO as a potential quantum spin liquid candidate.",2111.00925v1
+2021-11-18,Quantum magnetic properties and metal-to-insulator transition in chemically doped calcium ruthenate perovskite,"Ruthenates provide comprehensive platform to study a plethora of novel
+properties, such as quantum magnetism, superconductivity and magnetic
+fluctuation mediated metal-insulator transition. In this article, we provide an
+overview of quantum mechanical phenomenology in calcium ruthenium oxide with
+varying compositions. While the stochiometric composition of CaRuO$_{3}$
+exhibits non-Fermi liquid behavior with quasi-criticality, chemically doped
+compounds depict prominent signatures of quantum magnetic fluctuations at low
+temperature that in some cases are argued to mediate in metal-insulator
+transition. In the case of cobalt doped- CaRuO$_{3}$, an unusual continuum
+fluctuation is found to persist deep inside the glassy phase of the material.
+These observations reflect the richness of ruthenate research platform in the
+study of quantum magnetic phenomena of fundamental importance.",2111.09738v1
+2021-11-23,Magnetic-cations doped into a Double Perovskite Semiconductor,"We report two solid solutions based on magnetic ion doping of the double
+perovskite oxide Sr2GaSbO6: Sr2Ga1-xCrxSbO6 (0.1 < x < 0.4) and Sr2Ga1-xFexSbO6
+(0.1 < x < 0.4). All compositions crystallize in the same space group (I4/m) as
+their undoped parent phase Sr2GaSbO6, with the trivalent magnetic cations Cr3+
+or Fe3+ partially substituting for non-magnetic Ga3+ in one of the B-cation
+sites. The Cr- and Fe-doped phases display dominant antiferromagnetic coupling
+among the dopant magnetic moments, and exhibit decreasing band gaps with
+increasing substitution level.",2111.12015v1
+2022-04-26,Chirality-Induced Noncollinear Magnetization and Asymmetric Domain-Wall Propagation in Hydrogenated CoPd Thin Films,"Array-patterned CoPd-based heterostructures are created through e-beam
+lithography and plasma pretreatment that induces oxidation with depth gradient
+in the CoPd alloy films, breaking the central symmetry of the structure.
+Effects on the magnetic properties of the follow-up hydrogenation of the thin
+film are observed via magneto-optic Kerr effect microscopy. The system exhibits
+strong vertical and lateral antiferromagnetic coupling in the perpendicular
+component between the areas with and without plasma pretreatment, and
+asymmetric domain-wall propagation in the plasma-pretreated areas during
+magnetization reversal. These phenomenon exhibit evident magnetic chirality and
+can be interpreted with the Ruderman-Kittel-Kasuya-Yosida coupling and the
+Dzyaloshinskii-Moriya interaction (DMI). The sample processing demonstrated in
+this study allows easy incorporation of lithography techniques that can define
+areas with or without DMI to create intricate magnetic patterns on the sample,
+which provides an avenue towards more sophisticate control of canted spin
+textures in future spintronic devices.",2204.12428v1
+2022-12-08,Impact of a ferromagnetic insulating barrier in magnetic tunnel junctions,"We investigate spin-dependent conductance across a magnetic tunnel junction
+(MTJ) including a ferromagnetic insulating barrier. The MTJ consists of two
+half-metallic ferromagnetic La2/3Sr1/3MnO3 (LSMO) manganites as electrodes and
+La2NiMnO6 (LNMO) double perovskite as a ferromagnetic insulating barrier. The
+resistance of the junction is strongly dependent not only on the orientation of
+the magnetic moments in LSMO electrodes, but also on the direction of the
+magnetization of the LNMO barrier with respect to that of LSMO. The ratio of
+tunnel magnetoresistance reaches a maximum value of 24% at 10 K, and it
+decreases with temperature until it completely disappears above the critical
+temperature of LNMO at 280 K. The tunneling process is described using a
+mechanism which involves both empty and filled eg states of the LNMO barrier
+acting as a spin-filter. A magnetic insulating barrier is an interesting path
+for achieving room temperature magnetoresistance in oxide-based
+heterostructures.",2212.04416v1
+2023-06-13,Unraveling Magnetic Anisotropy Energy in Ferromagnetic Monolayer on Ferroelectric ABO$_3$ via DFT and Machine Learning,"Spin-based devices have attracted attention as an alternative to CMOS-based
+technology. However, one of the challenges in spintronics devices is reducing
+the spin-switching energy in ferromagnetic (FM) materials. To address this, we
+considered ferroelectric (FE) materials, which may affect the magnetic
+properties of FM materials. We explored various oxide perovskites ABO$_3$ as FE
+materials, onto which a Fe monolayer was placed as the FM material. We
+evaluated the magnetic anisotropy energy (MAE) of the Fe monolayer while
+varying the polarization of ABO$_3$. Our analysis showed that the MAE depends
+on the magnetic dipole moment induced in the FE material at the interface
+between the FE and FM materials due to structural modifications. Machine
+learning techniques were also employed to identify universal behaviors of the
+MAE in the presence of FE layers, confirming the importance of magnetic moments
+near the interface in explaining the dependence of the MAE on FE materials.",2306.07953v1
+2023-10-13,Emerging interfacial magnetization in isovalent manganite heterostructures driven by octahedral coupling,"The distortion of corner-sharing octahedra in isovalent perovskite
+transition-metal oxide interfaces is proven to be an excellent way to tailor
+the electronic and magnetic properties of their heterostructures. Combining
+depth-dependent magnetic characterization technique; (polarized neutron
+reflectivity, PNR); and theoretical calculation (density functional theory), we
+report interface-driven magnetic exchange interactions due to a modification in
+the octahedral rotations at the interfaces in an isovalent La0.67Ca0.33MnO3
+(LCMO)/La0.67Sr0.33MnO3 (LSMO) heterostructures. PNR results determined a
+length scale of ~ 8 unit cells at the interface, which demonstrated a
+modification in magnetic properties. The results also predicted a
+low-temperature exchange bias for these ferromagnetic heterostructures with a
+maximum exchange bias for the heterostructure, which showed an enhanced
+antiferromagnetic coupling at the interfaces.",2310.09059v1
+2023-11-11,Single-Phase L1$_{0}$-Ordered High Entropy Thin Films with High Magnetic Anisotropy,"The vast high entropy alloy (HEA) composition space is promising for
+discovery of new material phases with unique properties. We explore the
+potential to achieve rare-earth-free high magnetic anisotropy materials in
+single-phase HEA thin films. Thin films of FeCoNiMnCu sputtered on thermally
+oxidized Si/SiO$_{2}$ substrates at room temperature are magnetically soft,
+with a coercivity on the order of 10 Oe. After post-deposition rapid thermal
+annealing (RTA), the films exhibit a single face-centered-cubic (fcc) phase,
+with an almost 40-fold increase in coercivity. Inclusion of 50 at.% Pt in the
+film leads to ordering of a single L1$_{0}$ high entropy intermetallic phase
+after RTA, along with high magnetic anisotropy and a 3 orders of magnitude
+coercivity increase. These results demonstrate a promising HEA approach to
+achieve high magnetic anisotropy materials using RTA.",2311.06618v2
+2024-01-19,Anti-Jahn-Teller disproportionation and prospects for spin-triplet superconductivity in d-element compounds,"We argue that the unusual properties of a wide class of materials based on
+Jahn-Teller 3d and 4d ions with different crystal and electronic structures,
+from quasi-two-dimensional unconventional superconductors (cuprates,
+nickelates, ferropnictides/chalcogenides, ruthenate SrRuO4), manganites with
+local superconductivity to 3D ferrates (CaSr)FeO3, nickelates RNiO3 and silver
+oxide AgO with unusual charge and magnetic order can be explained within a
+single scenario. The properties of these materials are related to the
+instability of their highly symmetric Jahn-Teller ""progenitors"" with the ground
+orbital E-state to charge transfer with anti-Jahn-Teller disproportionation and
+the formation of a system of effective local composite spin-singlet or
+spin-triplet, electronic or hole bosons moving in a non-magnetic or magnetic
+lattice. These unusual systems are characterized by an extremely rich variety
+of phase states from non-magnetic and magnetic insulators to unusual metallic
+and superconducting states.",2401.11028v1
+2005-12-16,A Magnetic and Moessbauer Spectral Study of Core/Shell Structured Fe/Au Nanoparticles,"Fe/Au nanoparticles have been chemically synthesized through a reverse
+micelle reaction and investigated by both conventional and synchrotron based
+x-ray diffraction and by magnetic and Moessbauer spectral studies. The powder
+x-ray diffraction patterns reveal both the presence of crystalline alpha-iron
+and gold and the absence of any crystalline iron oxides or other crystalline
+products. First-order reversal curves, along with the major hysteresis loops of
+the Fe/Au nanoparticles have been measured as a function of time in order to
+investigate the evolution of their magnetic properties. The iron-57 Moessbauer
+spectra of both uncoated iron nanoparticles and the Fe/Au nanoparticles have
+been measured at 78 and 295 K and indicate that two major iron containing
+components are present, namely the expected alpha-iron and the unexpected
+amorphous Fe1-xBx alloy; several poorly crystallized ordered iron(III) oxide
+components as well as paramagnetic iron(II) and iron(III) components are also
+observed. These results indicate that the Fe-core/Au-shell nanoparticles
+synthesized through reverse micelles are far more complex that had been
+believed.",0512413v1
+2007-05-28,Dangling-bond spin relaxation and magnetic 1/f noise from the amorphous-semiconductor/oxide interface: Theory,"We propose a model for magnetic noise based on spin-flips (not
+electron-trapping) of paramagnetic dangling-bonds at the
+amorphous-semiconductor/oxide interface. A wide distribution of spin-flip times
+is derived from the single-phonon cross-relaxation mechanism for a
+dangling-bond interacting with the tunneling two-level systems of the amorphous
+interface. The temperature and frequency dependence is sensitive to three
+energy scales: The dangling-bond spin Zeeman energy delta, as well as the
+minimum (E_min) and maximum (E_max) values for the energy splittings of the
+tunneling two-level systems. We compare and fit our model parameters to a
+recent experiment probing spin coherence of antimony donors implanted in
+nuclear-spin-free silicon [T. Schenkel {\it et al.}, Appl. Phys. Lett. 88,
+112101 (2006)], and conclude that a dangling-bond area density of the order of
+10^{14}cm^{-2} is consistent with the data. This enables the prediction of
+single spin qubit coherence times as a function of the distance from the
+interface and the dangling-bond area density in a real device structure. We
+apply our theory to calculations of magnetic flux noise affecting SQUID devices
+due to their Si/SiO_2 substrate. Our explicit estimates of flux noise in SQUIDs
+lead to a noise spectral density of the order of 10^{-12}Phi_{0}^{2} {Hz}^{-1}
+at f=1Hz. This value might explain the origin of flux noise in some SQUID
+devices. Finally, we consider the suppression of these effects using surface
+passivation with hydrogen, and the residual nuclear-spin noise resulting from a
+perfect silicon-hydride surface.",0705.4088v3
+2009-10-11,Uniform spin chain physics arising from NCN bridges in CuNCN: surprises on the way from copper oxides to their nitride analogs,"We report on the unexpected uniform spin chain physics in CuNCN, the
+insulating nitride analog of copper oxides. Based on full-potential band
+structure calculations, we derive the relevant microscopic parameters, estimate
+individual exchange couplings, and establish a realistic spin model of this
+compound. The structure of CuNCN contains chains of edge-sharing CuN(4)
+squares. As a surprise, in contrast to analogous [CuO(2)] chains in
+""edge-sharing"" cuprates, the leading magnetic interactions J ~ 2500 K run
+perpendicular to the structural [CuN(2)] chains via bridging NCN groups. The
+resulting spin model of a uniform chain is in agreement with the experimentally
+observed temperature-independent magnetic susceptibility below 300 K. The
+nearest-neighbor and next-nearest-neighbor interactions along the structural
+[CuN(2)] chains are J(1) ~ -500 K and J(2) ~ 100 K, respectively. Despite the
+frustrating nature of J(1) and J(2), we assign the anomaly at 70 K to
+long-range magnetic ordering, which is likely collinear with antiparallel and
+parallel arrangement of spins along the 'c' and 'a' directions, respectively.
+The pronounced one-dimensionality of the spin system should lead to a reduction
+in the ordered moment and to a suppression of the transition anomaly in the
+specific heat, thus impeding the experimental observation of the long-range
+ordering. Our results suggest CuNCN as a promising material for ballistic heat
+transport within spin chains, while the sizable bandwidth W ~ 3 eV may lead to
+a metal-insulator transition and other exotic properties under high pressure.",0910.2056v1
+2010-04-07,Iron oxide doped boron nitride nanotubes: structural and magnetic properties,"A first-principles formalism is employed to investigate the interaction of
+iron oxide (FeO) with a boron nitride (BN) nanotube. The stable structure of
+the FeO-nanotube has Fe atoms binding N atoms, with bond length of roughly
+$\sim$2.1 \AA, and binding between O and B atoms, with bond length of 1.55 \AA.
+In case of small FeO concentrations, the total magnetic moment is
+(4$\mu_{Bohr}$) times the number of Fe atoms in the unit cell and it is
+energetically favorable to FeO units to aggregate rather than randomly bind to
+the tube. As a larger FeO concentration case, we study a BN nanotube fully
+covered by a single layer of FeO. We found that such a structure has square FeO
+lattice with Fe-O bond length of 2.11 \AA, similar to that of FeO bulk, and
+total magnetic moment of 3.94$\mu_{Bohr}$ per Fe atom. Consistently with
+experimental results, the FeO covered nanotube is a semi-half-metal which can
+become a half-metal if a small change in the Fermi level is induced. Such a
+structure may be important in the spintronics context.",1004.1151v2
+2010-07-13,Modeling of complex oxide materials from the first principles: systematic applications to vanadates RVO3 with distorted perovskite structure,"""Realistic modeling"" is a new direction of electronic structure calculations,
+where the main emphasis is made on the construction of some effective
+low-energy model entirely within a first-principle framework. Ideally, it is a
+model in form, but with all the parameters derived rigorously, on the basis of
+first-principles electronic structure calculations. The method is especially
+suit for transition-metal oxides and other strongly correlated systems, whose
+electronic and magnetic properties are predetermined by the behavior of some
+limited number of states located near the Fermi level. After reviewing general
+ideas of realistic modeling, we will illustrate abilities of this approach on
+the wide series of vanadates RVO3 (R= La, Ce, Pr, Nd, Sm, Gd, Tb, Yb, and Y)
+with distorted perovskite structure. Particular attention will be paid to
+computational tools, which can be used for microscopic analysis of different
+spin and orbital states in the partially filled t2g-band. We will explicitly
+show how the lifting of the orbital degeneracy by the monoclinic distortion
+stabilizes C-type antiferromagnetic (AFM) state, which can be further
+transformed to the G-type AFM state by changing the crystal distortion from
+monoclinic to orthorhombic one. Two microscopic mechanisms of such a
+stabilization, associated with the one-electron crystal field and electron
+correlation interactions, are discussed. The flexibility of the orbital degrees
+of freedom is analyzed in terms of the magnetic-state dependence of interatomic
+magnetic interactions.",1007.2058v1
+2011-10-21,Exchange-spring behavior in bimagnetic CoFe2O4/CoFe2 nanocomposite,"In this work we report a study of the magnetic behavior of ferrimagnetic
+oxide CoFe2O4 and ferrimagnetic oxide/ferromagnetic metal CoFe2O4/CoFe2
+nanocomposites. The latter compound is a good system to study hard
+ferrimagnet/soft ferromagnet exchange coupling. Two steps were used to
+synthesize the bimagnetic CoFe2O4/CoFe2 nanocomposites: (i) first preparation
+of CoFe2O4 nanoparticles using the a simple hydrothermal method and (ii) second
+reduction reaction of cobalt ferrite nanoparticles using activated charcoal in
+inert atmosphere and high temperature. The phase structures, particle sizes,
+morphology, and magnetic properties of CoFe2O4 nanoparticles have been
+investigated by X-Ray diffraction (XRD), Mossbauer spectroscopy (MS),
+transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM)
+with applied field up to 3.0 kOe at room temperature and 50K. The mean diameter
+of CoFe2O4 particles is about 16 nm. Mossbauer spectra reveal two sites for
+Fe3+. One site is related to Fe in an octahedral coordination and the other one
+to the Fe3+ in a tetrahedral coordination, as expected for a spinel crystal
+structure of CoFe2O4. TEM measurements of nanocomposite show the formation of a
+thin shell of CoFe2 on the cobalt ferrite and indicate that the nanoparticles
+increase to about 100 nm. The magnetization of nanocomposite showed hysteresis
+loop that is characteristic of the exchange spring systems. A maximum energy
+product (BH)max of 1.22 MGOe was achieved at room temperature for CoFe2O4/CoFe2
+nanocomposites, which is about 115% higher than the value obtained for CoFe2O4
+precursor. The exchange-spring interaction and the enhancement of product
+(BH)max in nanocomposite CoFe2O4/CoFe2 have been discussed.",1110.4905v1
+2013-05-13,Jumps in entropy and magnetic susceptibility at the valence and spin-state transition in a cobalt oxide,"A wide family of cobalt oxides of formulation (Pr,Ln,Ca)CoO3 (Ln being a
+lanthanide) exhibits a coupled valence and spin-state transition (VSST) at a
+temperature T*, which involves two concomitant modifications: (i) a change in
+the spin state of Co3+ from low-spin (T < T*) to a higher spin-state (T > T*),
+and (ii) a change in the valence state of Pr, from a mixed Pr4+/Pr3+ state (T <
+T*) to a purely trivalent state (T > T*), accompanied by an equivalent charge
+transfer within the Co3+/Co4+ subsystem. In the present paper, the VSST taking
+place in (Pr0.7Sm0.3)0.7Ca0.3CoO3 at T* = about 90 K is investigated by
+magnetization and heat capacity measurements. First, we quantitatively
+characterized the jumps in magnetic susceptibility (khi) and entropy (S) around
+T*. Then, these values were compared to those calculated as a function of the
+variations in the population of the different cationic species involved in the
+VSST. X-ray absorption spectroscopy experiments recently showed that the higher
+spin state above T* should be regarded as an inhomogeneous mixture between
+low-spin (LS) and high-spin (HS) states. In the frame of this description, we
+demonstrate that the jumps in both khi and S can be associated to the same
+change in the Co3+ HS content around T*. This result lends further support to
+the relevance of the LS/HS picture for the VSST, challenging the currently
+dominant interpretation based on the occurrence of an intermediate-spin (IS)
+state of Co3+ above T*.",1305.2829v1
+2014-09-11,Anisotropic magnetoresistance in antiferromagnetic Sr2IrO4,"We report point-contact measurements of anisotropic magnetoresistance (AMR)
+in a single crystal of antiferromagnetic (AFM) Mott insulator Sr2IrO4. The
+point-contact technique is used here as a local probe of magnetotransport
+properties on the nanoscale. The measurements at liquid nitrogen temperature
+revealed negative magnetoresistances (MRs) (up to 28%) for modest magnetic
+fields (250 mT) applied within the IrO2 a-b plane and electric currents flowing
+perpendicular to the plane. The angular dependence of MR shows a crossover from
+four-fold to two-fold symmetry in response to an increasing magnetic field with
+angular variations in resistance from 1-14%. We tentatively attribute the
+four-fold symmetry to the crystalline component of AMR and the field-induced
+transition to the effects of applied field on the canting of AFM-coupled
+moments in Sr2IrO4. The observed AMR is very large compared to the crystalline
+AMRs in 3d transition metal alloys/oxides (0.1-0.5%) and can be associated with
+the large spin-orbit interactions in this 5d oxide while the transition
+provides evidence of correlations between electronic transport, magnetic order
+and orbital states. The finding of this work opens an entirely new avenue to
+not only gain a new insight into physics associated with spin-orbit coupling
+but also better harness the power of spintronics in a more technically
+favorable fashion.",1409.3491v2
+2018-11-27,Self-consistent site-dependent DFT+$U$ study of stoichiometric and defective SrMnO$_3$,"We propose a self-consistent site-dependent Hubbard $U$ approach for DFT+$U$
+calculations of defects in complex transition-metal oxides, using Hubbard
+parameters computed via linear-response theory. The formation of a defect
+locally perturbs the chemical environment of Hubbard sites in its vicinity,
+resulting in different Hubbard $U$ parameters for different sites. Using oxygen
+vacancies in SrMnO$_3$ as a model system, we investigate the dependence of $U$
+on the chemical environment and study its influence on the structural,
+electronic, and magnetic properties of defective bulk and strained thin-film
+structures. Our results show that a self-consistent $U$ improves the
+description of stoichiometric bulk SrMnO$_3$ with respect to GGA or GGA+$U$
+calculations using an empirical $U$. For defective systems, $U$ changes as a
+function of the distance of the Hubbard site from the defect, its oxidation
+state and the magnetic phase of the bulk structure. Taking into account this
+dependence, in turn, affects the computed defect formation energies and the
+predicted strain- and/or defect-induced magnetic phase transitions, especially
+when occupied localized states appear in the band gap of the material upon
+defect creation.",1811.10858v2
+2016-05-01,Development of a method for measuring blood coagulation using superparamagnetic iron oxide nanoparticles and an alternating magnetic field,"We developed a method for measuring blood coagulation using superparamagnetic
+iron oxide nanoparticles (SPIONs) and an alternating magnetic field (AMF). The
+3rd and 5th harmonic signals from SPIONs mixed with blood induced by AMF were
+detected using a gradiometer coil. Blood coagulation was induced artificially
+by adding CaCl2 solution to whole blood of sheep at various temperatures and
+hematocrits. We calculated the coagulation rate (k) and normalized signal
+intensity at infinite time (Sinf) by fitting the time course of the normalized
+3rd harmonic signal to S(t)=(1-Sinf)exp(-kt)+Sinf. The k values increased
+significantly with increasing temperature and decreased significantly with
+increasing hematocrit. The Sinf values decreased significantly with increasing
+temperature and tended to increase with increasing hematocrit. Blood
+anticoagulation was induced by adding heparin to the whole blood sampled from
+mice. There were significant differences in both the 3rd and 5th harmonic
+signals between groups with and without heparin at 25 min or more after adding
+heparin. We also calculated the 3rd and 5th harmonic signals for viscosities
+ranging from 0.001 to 1 kg/m/s, with an assumption that the magnetization and
+particle size distribution of SPIONs obey the Langevin theory of paramagnetism
+and log-normal distribution, respectively. The 3rd and 5th harmonic signals
+increased slowly with increasing viscosity and had peaks at approximately 0.015
+and 0.025 kg/m/s, respectively. After these peaks, they decreased monotonically
+with increasing viscosity. These results confirm the rationale of our method.
+In conclusion, our method will be useful for measuring blood coagulation and
+anticoagulation and for studying their processes.",1605.00255v2
+2016-05-19,Hydration induced spin glass state in a frustrated Na-Mn-O triangular lattice,"Birnessite compounds are stable across a wide range of compositions that
+produces a remarkable diversity in their physical, electrochemical and
+functional properties. These are hydrated analogues of the magnetically
+frustrated, mixed-valent manganese oxide structures, with general formula,
+NaxMnO2. Here we demonstrate that the direct hydration of layered rock-salt
+type a-NaMnO2, with the geometrically frustrated triangular lattice topology,
+yields the birnessite type oxide, Na0.36MnO2 0.2H2O, transforming its magnetic
+properties. This compound has a much-expanded interlayer spacing compared to
+its parent a-NaMnO2 compound. We show that while the parent a-NaMnO2 possesses
+a Neel temperature of 45 K as a result of broken symmetry in the Mn3+
+sub-lattice, the hydrated derivative undergoes collective spin-freezing at 29 K
+within the Mn3+/Mn4+ sub-lattice. Scaling-law analysis of the frequency
+dispersion of the AC susceptibility, as well as the temperature-dependent,
+low-field DC magnetization confirm a cooperative spin-glass state of strongly
+interacting spins. This is supported by complementary spectroscopic analysis
+(HAADF-STEM, EDS, EELS) as well as by a structural investigation
+(high-resolution TEM, X-ray and neutron powder diffraction) that yield insights
+into the chemical and atomic structure modifications. We conclude that the
+spin-glass state in birnessite is driven by the spin-frustration imposed by the
+underlying triangular lattice topology that is further enhanced by the in-plane
+bond-disorder generated by the mixed-valent character of manganese in the
+layers.",1605.06067v1
+2018-10-25,Superdislocations and point defects in pyrochlore Yb2Ti2O7 single crystals and implication on magnetic ground states,"This study reports atomic-scale characterization of structural defects in
+Yb2Ti2O7, a pyrochlore oxide whose subtle magnetic interactions is prone to
+small perturbations. Due to discrepancies in the reported magnetic ground
+states, it has become a pressing issue to determine the nature of defects in
+this system. In the present study, we use atomic resolution scanning
+transmission electron microscopy techniques to identify the type of defects in
+the ytterbium titanate single crystals grown by the conventional optical
+floating zone (FZ) method. In addition to the known point defects of
+substitution Yb on Ti B-sites, extended defects such as dissociated
+superdislocations and anti-phase boundaries were discovered for the first time
+in this material. Such defects were prevalently observed in the FZ grown single
+crystals (of a darker color), in contrast to the stoichiometric white
+polycrystalline powders or high quality colorless single crystals grown by the
+traveling solvent floating zone (TSFZ) technique. The lattice strains from
+these extended defects result in distortions of Yb-tetrahedron. A change of Ti
+valance was not detected at the defects. Our findings provide new insights into
+understanding the nature of defects that are of great importance for the
+physical property studies of geometrically frustrated compounds. Furthermore,
+this work sheds light on the complicated core structure of superdislocations
+that have large Burgers vectors in oxides with complex unit cells.",1810.11055v1
+2020-04-07,Probing electronic and magnetic transitions of short periodic nickelate superlattices using synchrotron x-ray,"Transition metal based oxide heterostructures exhibit diverse emergent
+phenomena e.g. two dimensional electron gas, superconductivity, non-collinear
+magnetic phase, ferroelectricity, polar vortices, topological Hall effect etc.,
+which are absent in the constituent bulk oxides. The microscopic understandings
+of these properties in such nanometer thick materials are extremely
+challenging. Synchrotron x-ray based techniques such as x-ray diffraction,
+x-ray absorption spectroscopy (XAS), resonant x-ray scattering (RXS), resonant
+inelastic x-ray scattering (RIXS), x-ray photoemission spectroscopy, etc. are
+essential to elucidating the response of lattice, charge, orbital, and spin
+degrees of freedoms to the heterostructuring. As a prototypical case of complex
+behavior, rare-earth nickelates (RENiO3 with RE=La, Pr, Nd, Sm, Eu, Lu) based
+thin films and heterostructures have been investigated quite extensively in
+recent years. An extensive body of literature about these systems exists and
+for an overview of the field, we refer the interested readers to the recent
+reviews Annual Review of Materials Research 46, 305 (2016) and Reports on
+Progress in Physics 81, 046501 (2018). In the present article, we give a brief
+review that concentrates on the use of synchrotron based techniques to
+investigate a specific set of EuNiO3/LaNiO3 superlattices, specifically
+designed to solve a long-standing puzzle about the origin of simultaneous
+electronic, magnetic and structural transitions of the RENiO3 series.",2004.03100v1
+2017-09-22,Tuning electromagnetic properties of SrRuO3 epitaxial thin films via atomic control of cation vacancies,"Elemental defects in transition metal oxides is an important and intriguing
+subject that result in modifications in variety of physical properties
+including atomic and electronic structure, optical and magnetic properties.
+Understanding the formation of elemental vacancies and their influence on
+different physical properties is essential in studying the complex oxide thin
+films. In this study, we investigated the physical properties of epitaxial
+SrRuO3 thin films by systematically manipulating cation and/or oxygen
+vacancies, via changing the oxygen partial pressure (P(O2)) during the pulsed
+laser epitaxy (PLE) growth. Ru vacancies in the low-P(O2)-grown SrRuO3 thin
+films induce lattice expansion with the suppression of the ferromagnetic TC
+down to ~120 K. Sr vacancies also disturb the ferromagnetic ordering, even
+though Sr is not a magnetic element. Our results indicate that both A and B
+cation vacancies in an ABO3 perovskite can be systematically engineered via
+PLE, and the structural, electrical, and magnetic properties can be tailored
+accordingly.",1709.07600v1
+2018-08-20,Unconventional exchange bias coupling at perovskite/brownmillerite interface in spontaneously stabilized SrCoO3-δ/SrCoO2.5 bi-layer,"Interface effect in complex oxide thin film heterostructures lies at the
+vanguard of current research to design technologically relevant functionality
+and explore emergent physical phenomena. While most of the previous works focus
+on the perovskite/perovskite heterostructures, the study on
+perovskite/brownmillerite interfaces remain at its infancy. Here, we
+investigate spontaneously stabilized perovskite-ferromagnet
+(SrCoO3-{\delta})/brownmillertite-antiferromagnet (SrCoO2.5) bi-layer with TN >
+TC and discover an unconventional interfacial magnetic exchange bias effect.
+From magnetometry investigations, it is rationalized that the observed effect
+stems from the interfacial ferromagnet/antiferromagnet coupling. The
+possibility for coupled ferromagnet/spinglass interface engendering such effect
+is ruled out. Strikingly, a finite coercive field persists in the paramagnetic
+state of SrCoO3-{\delta} whereas the exchange bias field vanishes at TC. We
+conjecture the observed effect to be due to the effective external quenched
+staggered field provided by the antiferromagtic layer for the ferromagnetic
+spins at the interface. Our results not only unveil a new paradigm to tailor
+the interfacial magnetic properties in oxide heterostructures without altering
+the cations at the interface, but also provide a purview to delve into the
+fundamental aspects of exchange bias in such unusual systems paving a big step
+forward in thin film magnetism.",1808.06321v1
+2019-03-08,Spin stripe order in a square planar trilayer nickelate,"Trilayer nickelates, which exhibit a high degree of orbital polarization
+combined with an electron count (d8.67) corresponding to overdoped cuprates,
+have been identified as a promising candidate platform for achieving high-Tc
+superconductivity. One such material, La4Ni3O8, undergoes a
+semiconductor-insulator transition at ~105 K, which was recently shown to arise
+from the formation of charge stripes. However, an outstanding issue has been
+the origin of an anomaly in the magnetic susceptibility at the transition and
+whether it signifies formation of spin stripes akin to single layer nickelates.
+Here we report single crystal neutron diffraction measurements (both polarized
+and unpolarized) that establish that the ground state is indeed magnetic. The
+ordering is modeled as antiferromagnetic spin stripes that are commensurate
+with the charge stripes, the magnetic ordering occurring in individual
+trilayers that are essentially uncorrelated along the crystallographic c-axis.
+Comparison of the charge and spin stripe order parameters reveals that, in
+contrast to single-layer nickelates such as La2-xSrxNiO4 as well as related
+quasi-2D oxides including manganites, cobaltates, and cuprates, these orders
+uniquely appear simultaneously, thus demonstrating a stronger coupling between
+spin and charge than in these related low-dimensional correlated oxides.",1903.03246v2
+2019-08-09,Lattice small polarons and magnetic interactions drive preferential nanocrystal growth in silicon doped hematite,"Understanding the interplay between the structural, chemical and physical
+properties of nanomaterials is crucial for designing new devices with enhanced
+performance. In this regards, doping of metal oxides is a general strategy to
+tune size, morphology, charge, lattice, orbital and spin degrees of freedoms
+and has been shown to affect nanomaterials properties for photoelectrochemical
+water splitting, batteries, catalysis, magnetic applications and optics. Here
+we report the role of lattice small polaron in driving the morphological
+transition from nearly isotropic to nanowire crystals in Si doped hematite
+($\alpha-Fe_2O_3$). Lattice small polaron formation is well evidenced by the
+increase of hexagonal strain and degree of distortion of $FeO_6$ showing a
+hyperbolic trend with increasing Si content. Local analysis via pair
+distribution function highlights an unreported crossover from small to large
+polarons, which affects the correlation length of the polaronic distortion from
+short to average scales. Ferromagnetic double exchange interactions between
+$Fe^{2+}/Fe^{3+}$ species is found to be the driving force of the crossover,
+constraining the chaining of chemical bonds along the [110] crystallographic
+direction. This promotes the increase in the reticular density of Fe atoms
+along the hematite basal plane only, which boosts the anisotropic growth of
+nanocrystals with more extended [110] facets. Our results show that magnetic
+and electronic interactions drive preferential crystallographic growth in doped
+metal oxides, thus providing a new route to design their functional properties.",1908.03377v1
+2020-11-16,Ferroelectric tunnel junctions,"My research is dedicated to the electronic properties of functional oxides.
+My activity specifically focuses on ferroelectric tunnel junctions in which an
+ultrathin layer of ferroelectric material is intercalated between two metallic
+electrodes. In these devices, polarization reversal induces large modifications
+of the tunnel resistance, leading to a non-destructive readout of the
+information. After a demonstration of the concept with scanning probe
+microscopy techniques, I have been exploring the properties of ferroelectric
+tunnel junctions with various ferroelectric materials (BaTiO3, BiFeO3, and
+PVDF). I showed that these devices possess attractive properties for
+applications as non-volatile binary memories. In addition, exploring the fact
+that polarization usually reverses by the nucleation and propagation of
+domains, I demonstrated a memristive behavior in the junctions associated to
+non-uniform configurations of ferroelectric domains. Such ferroelectric
+memristors can be used as artificial synapses in neuromorphic architectures.
+Coupled to magnetic electrodes, the resulting multiferroic tunnel junctions
+enable a non-volatile control of magnetism at the ferroelectric/electrode
+interface and of the spin-polarized current associated. Besides this main
+activity on tunnel devices, I explored the influence of ferroelectricity on
+magnetic orders and on the properties of functional oxides.",2011.07864v1
+2021-09-13,Orbital selective switching of ferromagnetism in an oxide quasi two-dimensional electron gas,"Multi-orbital physics in quasi-two-dimensional electron gases (q2DEGs)
+triggers unique phenomena not observed in bulk materials, such as
+unconventional superconductivity and magnetism. Here, we investigate the
+mechanism of orbital selective switching of the spin-polarization in the oxide
+q2DEG formed at the (001) interface between the LaAlO$_{3}$, EuTiO$_{3}$ and
+SrTiO$_{3}$ band insulators. By using density functional theory calculations,
+transport, magnetic and x-ray spectroscopy measurements, we find that the
+filling of titanium-bands with 3d$_{xz,yz}$ orbital character in the EuTiO3
+layer and at the interface with SrTiO$_{3}$ induces an antiferromagnetic to
+ferromagnetic switching of the exchange interaction between Eu-4f$^{7}$
+magnetic moments. The results explain the observation of the carrier density
+dependent ferromagnetic correlations and anomalous Hall effect in this q2DEG,
+and demonstrate how combined theoretical and experimental approaches can lead
+to a deeper understanding of novel electronic phases and serve as a guide for
+the materials design for advanced electronic applications.",2109.06138v1
+2021-11-23,Microscopic Theory of Magnetic Disorder-Induced Decoherence in Superconducting Nb Films,"The performance of superconducting qubits is orders of magnitude below what
+is expected from theoretical estimates based on the loss tangents of the
+constituent bulk materials. This has been attributed to the presence of
+uncontrolled surface oxides formed during fabrication which can introduce
+defects and impurities that create decoherence channels. Here, we develop an ab
+initio Shiba theory to investigate the microscopic origin of magnetic-induced
+decoherence in niobium thin film superconductors and the formation of native
+oxides. Our ab initio calculations encompass the roles of structural disorder,
+stoichiometry, and strain on the formation of decoherence-inducing local spin
+moments. With parameters derived from these first-principles calculations we
+develop an effective quasi-classical model of magnetic-induced losses in the
+superconductor. We identify d-channel losses (associated with oxygen vacancies)
+as especially parasitic, resulting in a residual zero temperature surface
+impedance. This work provides a route to connecting atomic scale properties of
+superconducting materials and macroscopic decoherence channels affecting
+quantum systems.",2111.11684v1
+2023-04-26,Tunable Magnetic Properties in Sr$_2$FeReO$_6$ Double-Perovskite,"Double-perovskite oxides have attracted recent attention due to their
+attractive functionalities and application potential. In this paper, we
+demonstrate the effect of dual controls, i.e., the deposition pressure of
+oxygen (P$_O2$) and lattice mismatch ($\epsilon$), on tuning magnetic
+properties in epitaxial double-perovskite Sr$_2$FeReO$_6$ films. In a
+nearly-lattice-matched Sr$_2$FeReO$_6$/SrTiO$_3$ film, the
+ferrimagnetic-to-paramagnetic phase transition occurs when P$_O2$ is reduced to
+30 mTorr, probably due to the formation of Re$^{4+}$ ions that replace the
+stoichiometric Re$^{5+}$ to cause disorders of $B$-site ions. On the other
+hand, a large compressive strain or tensile strain shifts this critical P$_O2$
+to below 1 mTorr or above 40 mTorr, respectively. The observations could be
+attributed to the modulation of $B$-site ordering by epitaxial strain through
+affecting elemental valence. Our results provide a feasible way to expand the
+functional tunability of magnetic double-perovskite oxides that hold great
+promise for spintronic devices.",2304.13288v1
+2023-05-22,First-principles design of ferromagnetic monolayer MnO$_2$ at the complex interface,"Rapidly increasing interest in low-dimensional materials is driven by the
+emerging requirement to develop nanoscale
+  solid-state devices with novel functional properties that are not available
+in three-dimensional bulk phases.
+  Among the well-known low-dimensional systems, complex transition metal oxide
+interface holds promise for broad
+  applications in electronic and spintronics devices. Herein, intriguing
+metal-insulator and
+  ferromagnetic-antiferromagnetic transitions are achieved in monolayer MnO$_2$
+that is sandwiched into
+  SrTiO$_3$-based heterointerface systems through interface engineering.
+  By using first-principles calculations, we modeled three types of
+SrTiO$_3$-based heterointerface systems with different interface terminations
+and performed a comparative study on the spin-dependent magnetic and electronic
+properties that are established in the confined MnO$_2$ monolayer.
+First-principles study predicts that metal-insulator transition and magnetic
+transition in the monolayer MnO$_2$ are independent on the thickness of capping
+layers. Moreover, 100$\%$ spin-polarized two-dimensional electron gases
+accompanied by robust room temperature magnetism are uncovered in the monolayer
+MnO$_2$. Not only is the buried MnO$_2$ monolayer a new interface phase of
+fundamental physical interest, but it is also a promising candidate material
+for nanoscale spintronics applications. Our study suggests interface
+engineering at complex oxide interfaces is an alternative approach to designing
+high-performance two-dimensional materials.",2305.13549v1
+2023-06-26,Magnetic ground states and excitations in Zn-doped averieite -- a family of oxide-based $S=1/2$ kagome antiferromagnets,"Spin-1/2 kagome materials have recently attracted a resurgence of interest as
+they are considered an ideal host of the quantum spin liquid (QSL) state, which
+can underpin functionality such as superconductivity. Here we report the first
+synthesis and characterization of a new oxide-based distorted $S=1/2$ kagome
+antiferromagnet (KAFM) in the Zn$_x$Cu$_{5-x}$(VO$_4$)$_{2}$O$_2$CsCl (termed
+Zn$\mathbf {_x}$) series, namely Zn$_2$-averievite, Zn$\mathbf {_2}$ ($x=2$).
+Using magnetometry, synchrotron diffraction and neutron scattering we
+demonstrate an evolution of ground states with $x$ in Zn$\mathbf {_x}$; from
+long-range magnetic order in averievite ($x=0$), via a spin-glass-like ground
+state in Zn$\mathbf {_1}$, to a quantum spin liquid (QSL) in Zn$\mathbf {_2}$
+for which inelastic neutron scattering reveals a gapless continuum of
+excitations. Similar to archetypal $S = 1/2$ KAFMs herbertsmithite and
+SrCr$_{8.19}$Ga$_{3.81}$O$_{19}$ (SCGO), the dynamic magnetic susceptibility of
+Zn$\mathbf {_2}$ shows scaling behavior consistent with proximity to a quantum
+critical point. The results demonstrate that the new Zn$\mathbf {_2}$ material
+is an excellent test bed for achieving the elusive goal of charge carrier
+doping in QSL states of $S = 1/2$ KAFMs, in-line with previous theoretical
+studies.",2306.14739v1
+2012-05-29,Compositional Analysis of the High Molecular Weight Ethylene Oxide Propylene Oxide Copolymer by MALDI Mass Spectrometry,"The composition of narrow distribution poly ethylene oxide-propylene oxide
+copolymer (Mw ~ 8700 Da) was studied using matrix assisted laser desorption
+ionization (MALDI) mass spectrometry. The ethylene oxide-propylene oxide
+copolymer produced oligomers separated by 14 Da. The average resolving power
+over the entire spectrum was 28,000. Approximately 448 isotopically resolved
+peaks representing about 56 oligomers are identified. Although agreement
+between experimental and calculated isotopic distributions was strong, the
+compositional assignment was difficult. This is due to the large number of
+possible isobaric components. The purpose of this research is to resolve and
+study the composition of high mass copolymer such as ethylene oxide-propylene
+oxide.",1205.6421v1
+1998-06-01,Composite Polarons in Ferromagnetic Narrow-band Metallic Manganese Oxides,"A new mechanism is proposed to explain the colossal magnetoresistance and
+related phenomena. Moving electrons accompanied by Jahn-Teller phonon and
+spin-wave clouds may form composite polarons in ferromagnetic narrow-band
+manganites. The ground-state and finite-temperature properties of such
+composite polarons are studied in the present paper. By using a variational
+method, it is shown that the energy of the system at zero temperature decreases
+with the formation of composite polaron; the energy spectrum and effective mass
+of the composite polaron at finite temperature is found to be strongly
+renormalized by the temperature and the magnetic field. It is suggested that
+the composite polaron contribute significantly to the transport and the
+thermodynamic properties in ferromagnetic narrow-band metallic manganese
+oxides.",9806017v1
+2001-01-11,"Unusual valence, negative charge-transfer gaps and self-doping in transition-metal compounds","In this paper I discuss the electronic structure and properties of a
+specific, rather unconventional class of transition metal (TM) compounds, e.g.
+TM oxides, which formally have unusually high values of the oxidation state, or
+valence, of TM. In contrast to the typical situation, in this case the
+charge-transfer gap (excitation energy for the transfer of electrons from the
+ligands to the TM) is very small and may even become negative. As a result a
+profound modification of an electronic structure and of all the properties may
+take place: there appear holes in the oxygen p-bands (``self-doping''); the
+material may become the metal of a specific type; there may occur
+insulator--metal transitions of a specific type; magnetic properties may be
+quite different from the ones expected normally; the character of elementary
+excitations may change drastically. I give general discussion of such situation
+and consider several examples of corresponding systems and their specific
+properties.",0101164v1
+2001-07-12,Josephson junctions and superconducting quantum interference devices made by local oxidation of niobium ultrathin films,"We present a method for fabricating Josephson junctions and superconducting
+quantum interference devices (SQUIDs) which is based on the local anodization
+of niobium strip lines 3 to 6.5 nm-thick under the voltage-biased tip of an
+Atomic Force Microscope. Microbridge junctions and SQUID loops are obtained
+either by partial or total oxidation of the niobium layer. Two types of weak
+link geometries are fabricated : lateral constriction (Dayem bridges) and
+variable thickness bridges. SQUIDs based on both geometries show a modulation
+of the maximum Josephson current with a magnetic flux periodic with respect to
+the superconducting flux quantum h/2e. They persist up to 4K. The modulation
+shape and depth for SQUIDs based on variable thickness bridges indicate that
+the weak link size becomes comparable to the superconducting film coherence
+length which is of the order of 10nm.",0107273v1
+2001-10-12,Large Thermopower in Metallic Oxides: Misfit Cobaltites and Mangano-Ruthenates,"Two different kinds of metal transition oxides have been studied for their
+large thermopower values. The first one corresponds to the Tl-based misfit
+cobaltite which is a hole-doped metal. We demonstrate that the partial
+Bi-substitution for Tl in this phase induces an increase of the room
+temperature (RT) thermopower (TEP) value. Same result is obtained with the new
+Pb_{1/3}SrCoO_{3+delta} misfit corresponding to the Tl complete replacement by
+lead. Simultaneously, the T dependence of their resistivity exhibits a
+re-entrance below 70-90K where a large negative magnetoresistance is observed.
+Magnetic measurements reveal a strong interplay between spins and charges for
+this class of materials. Electron-doped (n-type) perovskite manganites are a
+second class of potential candidates for applications. In particular, the
+Ru^{4+/5+} substitution for Mn in the CaMnO_3 semi-conductor induces a drastic
+drop of the resistivity values. Metals with large RT TEP values and not too
+large thermal conductivities are generated. A comparison with best known
+materials, Bi_2Te_3 and NaCo_2O_4 is made.",0110270v1
+2002-02-06,Impurity-induced transition and impurity-enhanced thermopower in the thermoelectric oxide NaCo_{2-x}Cu_x$O_4,"Various physical quantities are measured and analysed for the Cu-substituted
+thermoelectric oxide NaCo_{2-x}Cu_xO_4. As was previously known, the
+substituted Cu enhances the thermoelectric power, while it does not increase
+the resistivity significantly. The susceptibility and the electron
+specific-heat are substantially decreased with increasing x, which implies that
+the substituted Cu decreases the effective-mass enhancement. Through a
+quantitative comparison with the heavy fermion compounds and the valence
+fluctuation systems, we have found that the Cu substitution effectively
+increases the coupling between the conduction electron and the magnetic
+fluctuation. The Cu substitution induces a phase transition at 22 K that is
+very similar to a spin-density-wave transition.",0202089v1
+2002-07-23,Study of Percolative Transitions with First-Order Characteristics in the Context of CMR Manganites,"The unusual magneto-transport properties of manganites are widely believed to
+be caused by mixed-phase tendencies and concomitant percolative processes.
+However, dramatic deviations from ""standard"" percolation have been unveiled
+experimentally. Here, a semi-phenomenological description of Mn oxides is
+proposed based on coexisting clusters with smooth surfaces, as suggested by
+Monte Carlo simulations of realistic models for manganites, also briefly
+discussed here. The present approach produces fairly abrupt percolative
+transitions and even first-order discontinuities, in agreement with
+experiments. These transitions may describe the percolation that occurs after
+magnetic fields align the randomly oriented ferromagnetic clusters believed to
+exist above the Curie temperature in Mn oxides. In this respect, part of the
+manganite phenomenology could belong to a new class of percolative processes
+triggered by phase competition and correlations.",0207560v2
+2003-02-13,Growth of Single Unit-Cell Superconducting La$_{2-x}$Sr$_x$CuO$_{4}$ Films,"We have developed an approach to grow high quality ultrathin films of
+La$_{2-x}$Sr$_x$CuO$_{4}$ with molecular beam epitaxy, by adding a
+homoepitaxial buffer layer in order to minimize the degradation of the film
+structure at the interface. The advantage of this method is to enable a further
+reduction of the minimal thickness of a superconducting
+La$_{1.9}$Sr$_{0.1}$CuO$_{4}$ film. The main result of our work is that a
+single unit cell (only two copper oxide planes) grown on a SrLaAlO$_4$
+substrate exhibits a superconducting transition at 12.5 K (zero resistance) and
+an in-plane magnetic penetration depth $\lambda_{ab}(0)$ = 535 nm.",0302261v1
+2003-12-31,Spinons in the strongly correlated copper oxide chains in SrCuO2,"We have investigated the spin dynamics in the strongly correlated chain
+copper oxide SrCuO$_2$ for energies up to $\gtrsim 0.6$ eV using inelastic
+neutron scattering. We observe an acoustic band of magnetic excitations which
+is well described by the ""Muller-ansatz"" for the two-spinon continuum in the
+S=1/2 antiferromagnetic Heisenberg spin chain. The lower boundary of the
+continuum extends up to $\approx 360$ meV, which corresponds to an exchange
+constant $J = 226(12)$ meV. Our finding that an effective Heisenberg spin
+Hamlitonian adequately describes the spin sector of this 1D electron system,
+even though its energy scale is comparable to that of charge excitations,
+provides compelling experimental evidence for spin-charge separation.",0312724v2
+2004-07-28,Room temperature tunneling magnetoresistance in magnetite based junctions: Influence of tunneling barrier,"Magnetite (Fe3O4) based tunnel junctions with turret/mesa structure have been
+investigated for different barrier materials (SrTiO3, NdGaO3, MgO, SiO2, and
+Al2O(3-x)). Junctions with a Ni counter electrode and an aluminium oxide
+barrier showed reproducibly a tunneling magnetoresistance (TMR) effect at room
+temperature of up to 5% with almost ideal switching behavior. This number only
+partially reflects the intrinsic high spin polarization of Fe3O4. It is
+considerably decreased due to an additional series resistance within the
+junction. Only SiO2 and Al2O(3-x) barriers provide magnetically decoupled
+electrodes as necessary for sharp switching. The observed decrease of the TMR
+effect as a function of increasing temperature is due to a decrease in spin
+polarization and an increase in spin-scattering in the barrier. Among the oxide
+half-metals magnetite has the potential to enhance the performance of TMR based
+devices.",0407725v1
+2004-09-07,Evidence for s-wave superconductivity in the new beta-pyrochlore oxide RbOs2O6,"We report the results of 87Rb NMR measurements on RbOs2O6, a new member of
+the family of the superconducting pyrochlore-type oxides with a critical
+temperature Tc = 6.4 K. In the normal state, the nuclear spin-lattice
+relaxation time T1 obeys the Korringa-type relation T1T = constant and the
+Knight shift is independent of temperature, indicating the absence of strong
+magnetic correlations. In the superconducting state, T1^{-1}(T) exhibits a tiny
+coherence enhancement just below Tc, and decreases exponentially with further
+decreasing temperatures. The value of the corresponding energy gap is close to
+that predicted by the conventional weak-coupling BCS theory. Our results
+indicate that RbOs2O6 is a conventional s-wave-type superconductor.",0409169v1
+2004-10-16,Phase transitions in spin-orbital coupled model for pyroxene titanium oxides,"We study the competing phases and the phase transition phenomena in an
+effective spin-orbital coupled model derived for pyroxene titanium oxides
+ATiSi2O6 (A=Na, Li). Using the mean-field-type analysis and the numerical
+quantum transfer matrix method, we show that the model exhibits two different
+ordered states, the spin-dimer and orbital-ferro state and the spin-ferro and
+orbital-antiferro state. The transition between two phases is driven by the
+relative strength of the Hund's-rule coupling to the onsite Coulomb repulsion
+and/or by the external magnetic field. The ground-state phase diagram is
+determined. There is a keen competition between orbital and spin degrees of
+freedom in the multicritical regime, which causes large fluctuations and
+significantly affects finite-temperature properties in the paramagnetic phase.",0410411v1
+2005-04-22,Characterizing the Hexagonality of Anodic Aluminium Oxide Nanoporous Arrays,"Nanoporous anodized alumina oxide have been used as templates for obtaining
+nanomaterials such as nanowires, which exhibit interesting electronic, magnetic
+and optical properties. This article presents how the regularity of the spatial
+distribution of pores in such templates, which affects several of the physical
+properties of the obtained nanomaterials, has been objectively quantified. The
+method uses adaptive thresholding, wave propagation image analysis methods, as
+well as an hexagonality measurement which was found to be particularly suitable
+because of its locality and invariance to translation, rotation and scaling. A
+comparison between commercial and laboratory-made samples is presented in order
+to test the method, resulting higher hexagonality for the latter type of
+templates.",0504573v1
+2005-05-09,Spin and orbital degrees of freedom in transition metal oxides and oxide thin films studied by soft x-ray absorption spectroscopy,"The class of transition metal compounds shows an enormous richness of
+physical properties, such as metal-insulator transitions, colossal
+magneto-resistance, super-conductivity, magneto-optics and spin-depend
+transport. It now becomes more and more clear that in order to describe
+transition metal compounds the charge, orbital, spin and lattice degrees of
+freedom should all be taken into account. With the recognition that the local
+orbital occupation plays an important role in many of the transition metal
+compounds there is a need for experimental techniques that can measure the
+orbital occupation. This technique is soft x-ray absorption spectroscopy.
+Within this PhD. Thesis we will illustrate the usefulness of this technique by
+some examples: 1) Magnetic versus crystal-field linear dichroism in NiO thin
+films. 2) The importance of spin-orbit coupling in CoO bulk and CoO thin films.
+3) Aligning spins in anti ferromagneticfilms using antiferromagnets. 4) The
+spin-state puzzle in the cobaltates. 5) Determination of the orbital momentum
+and crystal-field splitting in LaTiO3. 6) Orbital-assisted metal-insulator
+transition in VO2.",0505214v1
+2006-05-01,Ground State Properties and Optical Conductivity of the Transition Metal Oxide ${\rm Sr_{2}VO_{4}}$,"Combining first-principles calculations with a technique for many-body
+problems, we investigate properties of the transition metal oxide ${\rm
+Sr_{2}VO_{4}}$ from the microscopic point of view. By using the local density
+approximation (LDA), the high-energy band structure is obtained, while screened
+Coulomb interactions are derived from the constrained LDA and the GW method.
+The renormalization of the kinetic energy is determined from the GW method. By
+these downfolding procedures, an effective Hamiltonian at low energies is
+derived. Applying the path integral renormalization group method to this
+Hamiltonian, we obtain ground state properties such as the magnetic and orbital
+orders. Obtained results are consistent with experiments within available data.
+We find that ${\rm Sr_{2}VO_{4}}$ is close to the metal-insulator transition.
+Furthermore, because of the coexistence and competition of ferromagnetic and
+antiferromgnetic exchange interactions in this system, an antiferromagnetic and
+orbital-ordered state with a nontrivial and large unit cell structure is
+predicted in the ground state. The calculated optical conductivity shows
+characteristic shoulder structure in agreement with the experimental results.
+This suggests an orbital selective reduction of the Mott gap.",0605027v1
+2006-05-02,Spin Singlet State in Heptamers Emerging in Spinel Oxide AlV$_2$O$_4$,"We present our theoretical results on the electronic state in vanadium spinel
+oxide AlV$_2$O$_4$. The material is a mixed-valent system with the average
+valence V$^{2.5+}$, and V cations constitute a frustrated pyrochlore structure.
+It shows a structural transition at $\sim 700$ K, leading to the formation of
+seven V-sites clusters -- heptamers. We study the electronic state of the
+heptamer by explicitly taking account of orbital degree of freedom as well as
+electron correlations. We show that the ground state of the heptamer for
+realistic parameters becomes spin-singlet because of strong $\sigma$-type
+bonding states of $t_{2g}$ orbitals. The temperature dependence of the magnetic
+susceptibility in experiments is naturally understood by this singlet formation
+in heptamers. Our results indicate that in AlV$_2$O$_4$ orbital physics is
+relevant to stabilize a cluster-type singlet state instead of a previously
+proposed charge-ordered state with valence skipping.",0605046v2
+2006-10-25,High quality Fe3-deltaO4/InAs hybrid structure for electrical spin injection,"Single Crystalline Fe3-deltaO4 (0<=delta<=0.33) films have been epitaxially
+grown on InAs (001) substrates by molecular beam epitaxy using O2 as source of
+active oxygen. Under optimum growth conditions in-situ real time reflection
+high-energy electron diffraction patterns along with ex-situ atomic force
+microscopy indicated the (001) Fe3-deltaO4 to be grown under step-flow-growth
+mode with a characteristic surface reconstruction. X-ray photoelectron
+spectroscopy demonstrate the possibility to obtain iron oxides with
+compositions ranging from Fe3O4 to gamma-Fe2O3. Superconducting quantum
+interference device magnetometer at 300K shows well behaved magnetic properties
+giving therefore credibility to the promise of iron based oxides for spintronic
+applications.",0610697v1
+2007-02-20,Anomalous electric conductions in KSbO3-type metallic rhenium oxides,"Single crystals of KSbO3-type rhenium oxides, La4Re6O$19, Pb6Re6O19, Sr2Re3O9
+and Bi3Re3O11, were synthesized by a hydrothermal method. Their crystal
+structures can be regarded as a network of three-dimensional orthogonal-dimer
+lattice of edge-shared ReO6 octahedra. All of them exhibit small magnitude of
+Pauli paramagnetism, indicating metallic electronic states without strong
+electron correlations. The resistivity of these rhenates, except Bi3Re3O11,
+have a temperature dependence of $rho(T)=\rho_{0}+AT^{n}$ $(n \approx 1.6)$ in
+a wide temperature range between 5 K and 300 K, which is extraordinary for
+three-dimensional metals without strong electron correlations. The resistivity
+of Bi3Re3O11 shows an anomaly around at 50 K, where the magnetic susceptibility
+also detects a deviation from ordinary Pauli paramagnetism.",0702451v1
+2007-07-14,Influence of oxygen vacancy on the electronic structure of HfO$_2$ film,"We investigated the unoccupied part of the electronic structure of the
+oxygen-deficient hafnium oxide (HfO$_{\sim1.8}$) using soft x-ray absorption
+spectroscopy at O $K$ and Hf $N_3$ edges. Band-tail states beneath the
+unoccupied Hf 5$d$ band are observed in the O $K$-edge spectra; combined with
+ultraviolet photoemission spectrum, this indicates the non-negligible
+occupation of Hf 5$d$ state. However, Hf $N_3$-edge magnetic circular dichroism
+spectrum reveals the absence of a long-range ferromagnetic spin order in the
+oxide. Thus the small amount of $d$ electron gained by the vacancy formation
+does not show inter-site correlation, contrary to a recent report [M.
+Venkatesan {\it et al.}, Nature {\bf 430}, 630 (2004)].",0707.2127v1
+2007-09-13,Ferromagnetism in 2p Light Element-Doped II-oxide and III-nitride Semiconductors,"II-oxide and III-nitride semiconductors doped by nonmagnetic 2p light
+elements are investigated as potential dilute magnetic semiconductors (DMS).
+Based on our first-principle calculations, nitrogen doped ZnO, carbon doped
+ZnO, and carbon doped AlN are predicted to be ferromagnetic. The ferromagnetism
+of such DMS materials can be attributed to a p-d exchange-like p-p coupling
+interaction which is derived from the similar symmetry and wave function
+between the impurity (p-like t_2) and valence (p) states. We also propose a
+co-doping mechanism, using beryllium and nitrogen as dopants in ZnO, to enhance
+the ferromagnetic coupling and to increase the solubility and activity.",0709.2059v1
+2007-10-04,Structure and dynamics of Oxide Melts and Glasses : a view from multinuclear and high temperature NMR,"Solid State Nuclear Magnetic Resonance (NMR) experiments allow characterizing
+the local structure and dynamics of oxide glasses and melts. Thanks to the
+development of new experiments, it now becomes possible to evidence not only
+the details of the coordination state of the network formers of glasses but
+also to characterize the nature of polyatomic molecular motifs extending over
+several chemical bonds. We present results involving 31P homonuclear
+experiments that allow description of groups of up to three phosphate units and
+27Al/17O heteronuclear that allows evidencing &#956;3 oxygen bridges in
+aluminate glasses and rediscussion of the structure of high temperature melts.",0710.1003v1
+2008-04-02,Origin and control of high-temperature ferromagnetism in semiconductors,"The extensive experimental and computational search for multifunctional
+materials has resulted in the development of semiconductor and oxide systems,
+such as (Ga,Mn)N, (Zn,Cr)Te, and HfO2, which exhibit surprisingly stable
+ferromagnetic signatures despite having a small or nominally zero concentration
+of magnetic elements. Here, we show that the ferromagnetism of (Zn,Cr)Te, and
+the associated magnetooptical and magnetotransport functionalities, are
+dominated by the formation of Cr-rich (Zn,Cr)Te metallic nanocrystals embedded
+in the Cr-poor (Zn,Cr)Te matrix. Importantly, the formation of these
+nanocrystals can be controlled by manipulating the charge state of Cr ions
+during the epitaxy. The findings provide insight into the origin of
+ferromagnetism in a broad range of semiconductors and oxides, and indicate
+possible functionalities of these composite systems. Furthermore, they
+demonstrate a bottom-up method for self-organized nanostructure fabrication
+that is applicable to any system in which the charge state of a constituent
+depends on the Fermi-level position in the host semiconductor.",0804.0322v1
+2008-08-22,Ferromagnetism in transparent Mn(II)-doped indium tin oxide films prepared by sol-gel process,"We observe remarkably strong room temperature ferromagnetism (~1.5 Bohr
+Magneton/Mn) in optically transparent Mn(II)-doped indium tin oxide (ITO)
+films. The nanocrystalline films with average grain size 10-22 nm and thickness
+150-350 nm are prepared by sol-gel coating technique on sodalime silica glass
+substrate. The ferromagnetic property is, of course, weak for films deposited
+on pure silica glass substrate. The structural parameters of the films appear
+to be governing the magnetic property strongly which vary appreciably depending
+on the substrate. The observation of room temperature ferromagnetism in
+transparent conducting ITO films may find a plethora of applications in the
+area of magneto-optics.",0808.3063v1
+2008-09-17,The effect of Coulomb interaction at ferromagnetic-paramagnetic metallic perovskite junctions,"We study the effect of Coulomb interactions in transition metal oxides
+junctions. In this paper we analyze charge transfer at the interface of a three
+layer ferromagnetic-paramagnetic-ferromagnetic metallic oxide system. We choose
+a charge model considering a few atomic planes within each layer and obtain
+results for the magnetic coupling between the ferromagnetic layers. For large
+number of planes in the paramagnetic spacer we find that the coupling
+oscillates with the same period as in RKKY but the amplitude is sensitive to
+the Coulomb energy. At small spacer thickness however, large differences may
+appear as function of : the number of electrons per atom in the ferromagnetics
+and paramagnetics materials, the dielectric constant at each component, and the
+charge defects at the interface plane emphasizing the effects of charge
+transfer.",0809.2984v1
+2009-03-29,Anisotropic spin fluctuations and multiple superconducting gaps in hole-doped Ba_0.7K_0.3Fe_2As_2: NMR in a single crystal,"We report the first ^{75}As-NMR study on a single crystal of the hole-doped
+iron-pnictide superconductor Ba_{0.7}K_{0.3}Fe_2As_{2} (T_c = 31.5 K). We find
+that the Fe antiferromagnetic spin fluctuations are anisotropic and are weaker
+compared to underdoped copper-oxides or cobalt-oxide superconductors. The spin
+lattice relaxation rate 1/T_1 decreases below T_c with no coherence peak and
+shows a step-wise variation at low temperatures, which is indicative of
+multiple superconducting gaps, as in the electron-doped
+Pr(La)FeAsO$_{1-x}$F$_{x}$. Furthermore, no evidence was obtained for a
+microscopic coexistence of a long-range magnetic and superconductivity.",0903.5098v2
+2009-07-27,Evidence of kinetically arrested supercooled phases in the pervoskite oxide NdNiO$_3$,"We report the time and temperature dependent response of thermopower in the
+non-magnetic perovskite oxide NdNiO$_3$. We find that on cooling below the
+metal-insulator transition temperature the system evolves into a phase
+separated state which consists of supercooled metallic and insulating phases.
+This phase separated state exhibits out of equilibrium features such as cooling
+rate dependence and time dependence. The existence of these dynamical features
+is attributed to the transformation of supercooled metallic phases to the
+insulating state. On cooling a small fraction of supercooled phases gets
+kinetically arrested in a glassy state and these supercooled phases remain in
+that state down to low temperature. In the heating cycle the arrested states
+dearrest above 150 K and this results in the reappearance of time dependent
+features.",0907.4512v1
+2009-09-16,"Superconductivity at 39 K in New Iron Pnictide Oxide (Fe2As2)(Sr4(Mg,Ti)2O6)","We have discovered a new iron pnictide oxide superconductor
+(Fe2As2)(Sr4(Mg,Ti)2O6). This material is isostructual with (Fe2As2)(Sr4M2O6)
+(M = Sc, Cr), which was found in our previous study. The structure of this
+compound is tetragonal with a space group of P4/nmm and consists of the
+anti-fluorite type FeAs and perovskite-type blocking layers. The lattice
+constants are a = 3.935 A and c = 15.952 A for (Fe2As2)(Sr4MgTiO6). In both
+magnetization and resistivity measurements, this compound exhibits
+superconductivity below 10 K. Moreover, ratio of Mg and Ti in this compound can
+be changed toward Ti-rich composition. (Fe2As2)(Sr4Mg1-xTi1+xO6) phase is
+obtained at 0 < x as a main phase, and Tc and superconducting volume fraction
+increase with increasing x. The highest Tc(onset) was confirmed at 39 K for x =
+0.6 in resistivity measurement.",0909.2945v3
+2009-10-27,Optically induced softening of the charge-transfer gap in Sr2CuO2Cl2,"Energy- and time-resolved spectroscopy reveals a photoinduced softening of
+the charge-transfer gap in the insulating copper oxide Sr2CuO2Cl2 that
+indicates rapid and efficient photoproduction of optical phonons. By relating
+the pump-probe signal amplitude to the thermal difference spectrum, we estimate
+that eleven to twenty optical phonons are created for every one 3 eV photon.
+Assuming relaxation to the optical absorption edge at 1.5 eV, this corresponds
+to 70-130 meV per boson. While the lower limit is consistent with relaxation
+exclusively through optical phonons, the upper limit suggests a significant
+role for magnetic excitations. We observe a photoinduced bleaching of the gap
+excitation that we associate with phase space filling, and estimate the
+excluded area of the photoexcited state to be about nine copper oxide
+plaquettes. The temporal decay of the pump-probe signal is consistent with
+anharmonic phonon decay.",0910.5048v1
+2010-06-18,Tunable magnetic interaction at the atomic scale in oxide heterostructures,"We report on a systematic study of a number of structurally identical but
+chemically distinct transition metal oxides in order to determine how the
+material-specific properties such as the composition and the strain affect the
+properties at the interface of heterostructures. Our study considers a series
+of structures containing two layers of ferromagnetic SrRuO3, with
+antiferromagnetic insulating manganites sandwiched in between. The results
+demonstrate how to control the strength and relative orientation of interfacial
+ferromagnetism in correlated electron materials by means of valence state
+variation and substrate-induced strain, respectively.",1006.3603v2
+2010-06-18,"A New Iron Pnictide Oxide (Fe2As2)(Ca5(Mg,Ti)4Oy) and a New Phase in Fe-As-Ca-Mg-Ti-O system","A new layered iron arsenide oxide (Fe2As2)(Ca5(Mg,Ti)4Oy) and its structural
+derivative were found in the Fe-As-Ca-Mg-Ti-O system. The crystal structure of
+(Fe2As2)(Ca5(Mg,Ti)4Oy) is identical to that of (Fe2As2)(Ca5(Sc,Ti)4Oy), which
+was reported in our previous study. The lattice constants of this compound are
+a = 3.86(4) A and c = 41.05(2) A. In addition, another phase with a thicker
+blocking layer was found. The structure of the compound and its derivative was
+tentatively assigned through STEM observation as (Fe2As2)(Ca8(Mg,Ti)6Oy) with
+sextuple perovskite-type sheets divided by a rock salt layer. The interlayer
+Fe-Fe distance of this compound is ~30 A. The compound and its derivative
+exhibited bulk superconductivity, as found from magnetization and resistivity
+measurements.",1006.3769v4
+2010-08-31,"Total scattering descriptions of local and cooperative distortions in the oxide spinel (Mg,Cu)Cr2O4 with dilute Jahn-Teller ions","The normal spinel oxide MgCr2O4 is cubic at room temperature while the normal
+spinel CuCr2O4 is tetragonal as a consequence of the Jahn-Teller nature of Cu2+
+on the tetrahedral sites. Despite different end-member structures, complete
+solid solutions of Mg_{1-x}Cu_xCr2O4 can be prepared that display a first-order
+structural transition with composition x = 0.43 at room temperature. Reverse
+Monte Carlo analysis of total neutron scattering on data acquired between 300 K
+and 15 K on samples with x = 0.10, 0.20, and 0.43 provides unbiased local and
+average structure descriptions of the samples, including an understanding of
+the transition from local Jahn-Teller distortions in the cubic phase to
+cooperative distortions that result in a tetragonal structure. Distributions of
+continuous symmetry measures help to understand and distinguish distorted and
+undistorted coordination around the tetrahedral site in the solid solutions.
+Magnetic exchange bias is observed in field-cooled hysteresis loops of samples
+with dilute Cu2+ concentration and in samples with tetragonal--cubic phase
+coexistence around 300 K.",1008.5363v4
+2011-02-18,Structure of graphene oxide: thermodynamics versus kinetics,"Graphene oxide (GO) is an important intermediate to prepare graphene and it
+is also a versatile material with various applications. However, despite its
+importance, the detailed structure of GO is still unclear. For example,
+previous theoretical studies based on energetics have suggested that hydroxyl
+chain is an important structural motif of GO, which, however, is found to be
+contrary to nuclear magnetic resonance (NMR) experiment. In this study, we
+check both thermodynamic and kinetic aspects missed previously. First
+principles thermodynamics gives a free energy based stability ordering similar
+to that based on energetics, and hydroxyl chain is thus thermodynamically still
+favorable. At the same time, by checking the calculated vibrational
+frequencies, we note that hydroxyl chain structure is also inconsistent with
+infrared experiment. Therefore, kinetics during GO synthesis is expected to
+make an important role in GO structure. Transition state calculations predict
+large energy barriers between local minima, which suggests that experimentally
+obtained GO has a kinetically constrained structure.",1102.3797v1
+2011-07-21,Superconductivity and Ferromagnetism in Oxide Interface Structures: Possibility of Finite Momentum Pairing,"We introduce a model to explain the observed ferromagnetism and
+superconductivity in LAO/STO oxide interface structures. Due to the polar
+catastrophe mechanism, 1/2 charge per unit cell is transferred to the interface
+layer. We argue that this charge localizes and orders ferromagnetically via
+exchange with the conduction electrons. Ordinarily this ferromagnetism would
+destroy superconductivity, but due to strong spin-orbit coupling near the
+interface, the magnetism and superconductivity can coexist by forming an
+FFLO-type condensate of Cooper pairs at finite momentum, which is surprisingly
+robust in the presence of strong disorder.",1107.4352v3
+2011-10-31,Spin Transfer from a Ferromagnet into a Semiconductor through an Oxide barrier,"We present results on the magnetoresistance of the system Ni/Al203/n-doped
+Si/Al2O3/Ni in fabricated nanostructures. The results at temperature of 14K
+reveal a 75% magnetoresistance that decreases in value up to approximately 30K
+where the effect disappears. We observe minimum resistance in the antiparallel
+configurations of the source and drain of Ni. As a possibility, it seems to
+indicate the existence of a magnetic state at the Si/oxide interface. The
+average spin diffusion length obtained is of 650 nm approximately. Results are
+compared to the window of resistances that seems to exist between the tunnel
+barrier resistance and two threshold resistances but the spin transfer seems to
+work in the range and outside the two thresholds.",1110.6810v1
+2012-02-07,Universal conductance fluctuations in indium tin oxide nanowires,"Magnetic field dependent universal conductance fluctuations (UCF's) are
+observed in weakly disordered indium tin oxide nanowires from 0.26 K up to
+$\sim 25$ K. The fluctuation magnitudes increase with decreasing temperature,
+reaching a fraction of $e^2/h$ at $T \lesssim 1$ K. The shape of the UCF
+patterns is found to be very sensitive to thermal cycling of the sample to room
+temperatures, which induces irreversible impurity reconfigurations. On the
+other hand, the UCF magnitudes are insensitive to thermal cycling. Our measured
+temperature dependence of the root-mean-square UCF magnitudes are compared with
+the existing theory [C. W. J. Beenakker and H. van Houten, Phys. Rev. B
+\textbf{37}, 6544 (1988)]. A notable discrepancy is found, which seems to imply
+that the experimental UCF's are not cut off by the thermal diffusion length
+$L_T$, as would be expected by the theoretical prediction when $L_T <
+L_\varphi$, where $L_\varphi$ is the electron dephasing length. The approximate
+electron dephasing length is inferred from the UCF magnitudes and compared with
+that extracted from the weak-localization magnetoresistance studies. A
+reasonable semiquantitative agreement is observed.",1202.1329v1
+2012-02-22,Coexistance of giant tunneling electroresistance and magnetoresistance in an all-oxide magnetic tunnel junction,"We demonstrate with first-principles electron transport calculations that
+large tunneling magnetoresistance (TMR) and tunneling electroresistance (TER)
+effects can coexist in an all-oxide device. The TMR originates from the
+symmetry-driven spin filtering provided by the insulating BaTiO3 barrier to the
+electrons injected from SrRuO3. In contrast the TER is possible only when a
+thin SrTiO3 layer is intercalated at one of the SrRuO3/BaTiO3 interfaces. As
+the complex band-structure of SrTiO3 has the same symmetry than that of BaTiO3,
+the inclusion of such an intercalated layer does not negatively alter the TMR
+and in fact increases it. Crucially, the magnitude of the TER also scales with
+the thickness of the SrTiO3 layer. The SrTiO3 thickness becomes then a single
+control parameter for both the TMR and the TER effect. This protocol offers a
+practical way to the fabrication of four-state memory cells.",1202.4919v1
+2012-06-28,Competing misfit relaxation mechanisms in epitaxial correlated oxides,"Strain engineering of functional properties in epitaxial thin films of
+strongly correlated oxides exhibiting octahedral-framework structures is
+hindered by the lack of adequate misfit relaxation models. Here we present
+unreported experimental evidences of a four-stage hierarchical development of
+octahedral-framework perturbations resulting from a progressive imbalance
+between electronic, elastic and octahedral tilting energies in La0.7Sr0.3MnO3
+epitaxial thin films grown on SrTiO3 substrates. Electronic softening of the Mn
+- O bonds near the substrate leads to the formation of an interfacial layer
+clamped to the substrate with strongly degraded magnetotransport properties,
+i.e. the so-called dead layer, while rigid octahedral tilts become relevant at
+advanced growth stages without significant effects on charge transport and
+magnetic ordering.",1206.6680v2
+2012-07-20,The Magnetoelectric Effect in Transition Metal Oxides: Insights and the Rational Design of New Materials from First Principles,"The search for materials displaying a large magnetoelectric effect has
+occupied researchers for many decades. The rewards could include not only
+advanced electronics technologies, but also fundamental insights concerning the
+dielectric and magnetic properties of condensed matter. In this article, we
+focus on the magnetoelectric effect in transition metal oxides and review the
+manner in which first-principles calculations have helped guide the search for
+(and increasingly, predicted) new materials and shed light on the microscopic
+mechanisms responsible for magnetoelectric phenomena.",1207.5026v2
+2012-09-24,Ba1-xNaxTi2Sb2O (0.0 <= x <= 0.33): A Layered Titanium-based Pnictide Oxide Superconductor,"A new layered Ti-based pnictide oxide superconductor, Ba1-xNaxTi2Sb2O (0.0 <=
+x <= 0.33), is reported. X-ray studies reveal it crystallizes in the tetragonal
+CeCr2Si2C structure. The undoped parent compound, BaTi2Sb2O (P4/mmm;
+a=4.1196(1){\AA}; c=8.0951(2){\AA}), exhibits a CDW/SDW transition at 54K. Upon
+chemical doping with Na, the CDW/SDW transition is systematically suppressed
+and super-conductivity arises with the critical temperatures, Tc, increasing to
+5.5 K. Bulk superconductivity is confirmed by resistivity, magnetic and heat
+capacity measurements. Like the high-Tc cuprates and the iron pnictides,
+superconductivity in BaTi2Sb2O arises from an ordered state. Similarities and
+differences to the cuprate and iron pnictide supercon-ductors are discussed.",1209.5447v2
+2013-01-17,Giant Magnetoresistance Effect in the Metal-Insulator Transition of Pyrochlore Oxide Nd2Ir2O7,"We investigated the magnetoresistance (MR) effect of the pyrochlore oxide
+Nd2Ir2O7, which shows a metal-insulator transition at T_MI =33 K. A small
+positive MR effect was observed in the metallic state above T_MI, while a large
+negative MR effect was observed in the insulating state below T_MI . MR effects
+exceeding 3000% were found at 1 K at a field of 9 T. As a result, we confirmed
+the crossover from the insulating state to a state with a small or partial band
+gap in a field up to 56 T. Furthermore, from the MR effect in Eu2Ir2O7 (T_MI =
+120 K) and Gd$_2$Ir$_2$O$_7$ (T_MI = 127 K), we revealed that the large
+negative MR effect of the pyrochlore iridate Ln2Ir2O7 depends on the magnetism
+of the lanthanide Ln^{3+} ion. The d-f interaction plays a significant role in
+the large negative MR effect in the insulating state.",1301.3969v1
+2013-03-05,Interplay of octahedral rotations and breathing distortions in charge ordering perovskite oxides,"We investigate the structure--property relationships in $AB$O$_3$ perovskites
+exhibiting octahedral rotations and cooperative octahedral breathing
+distortions (CBD) using group theoretical methods. Rotations of octahedra are
+ubiquitous in the perovskite family, while the appearance of breathing
+distortions -- oxygen displacement patterns that lead to approximately uniform
+dilation and contraction of the $B$O$_6$ octahedra -- are rarer in compositions
+with a single, chemically unique $B$-site. The presence of a CBD relies on
+electronic instabilities of the $B$-site cations, either orbital degeneracies
+or valence-state fluctuations, and often appear concomitant with charge order
+metal--insulator transitions or $B$-site cation ordering. We enumerate the
+structural variants obtained from rotational and breathing lattice modes and
+formulate a general Landau functional describing their interaction. We use this
+information and combine it with statistical correlation techniques to evaluate
+the role of atomic scale distortions on the critical temperatures in
+representative charge ordering nickelate and bismuthate perovskites. Our
+results provide new microscopic insights into the underlying
+structure--property interactions across electronic and magnetic phase
+boundaries, suggesting plausible routes to tailor the behavior of functional
+oxides by design.",1303.0903v2
+2013-07-25,Reentrant Superconductivity and Superconducting Critical Temperature Oscillations in F/S/F trilayers of Cu41Ni59/Nb/Cu41Ni59 Grown on Cobalt Oxide,"Ferromagnet/Superconductor/Ferromagnet (F/S/F) trilayers constitute the core
+of a superconducting spin valve. The switching effect of the spin valve is
+based on interference phenomena occurring due to the proximity effect at the
+S/F interfaces. A remarkable effect is only expected if the core structure
+exhibits strong critical temperature oscillations, or most favorable, reentrant
+superconductivity, when the thickness of the ferromagnetic layer is increased.
+The core structure has to be grown on an antiferromagnetic oxide layer (or such
+layer to be placed on top) to pin by exchange bias the
+magnetization-orientation of one of the ferromagnetic layers. In the present
+paper we demonstrate that this is possible, keeping the superconducting
+behavior of the core structure undisturbed.",1307.6737v1
+2013-10-29,Theory of Antiferromagnetic Order in High-Tc Oxides: An Approach Based on Ginzburg-Landau Expansion,"The mean-field phase diagram of antiferromagnetic order in t-J model has been
+examined, using the free energy obtained by Ginzburg-Landau (GL) expansion. We
+extended the usual GL theory in two ways: First, we have included higher order
+terms with respect to the spatial derivative (or wave number) to incorporate
+the incommensurate antiferromagnetic order. Second, we have also included
+higher order terms with respect to the order parameter amplitude, in order to
+treat the first order phase transition between paramagnetic and
+antiferromagnetic phase, which appears at some doping rates. We found the
+possibility of tricritical point and critical endpoint in the magnetic phase
+diagram of the high-Tc oxides associated with the commensurate and
+incommensurate antiferromagnetic order. The possible effects of thermal
+fluctuations and randomness (spin glass) are also discussed qualitatively based
+on the GL free energy.",1310.7777v1
+2014-01-16,Active silicon integrated nanophotonics: ferroelectric BaTiO3 devices,"The integration of complex oxides on silicon presents opportunities to extend
+and enhance silicon technology with novel electronic, magnetic, and photonic
+properties. Among these materials, barium titanate (BaTiO3) is a particularly
+strong ferroelectric perovskite oxide with attractive dielectric and
+electro-optic properties. Here we demonstrate nanophotonic circuits
+incorporating ferroelectric BaTiO3 thin films on the ubiquitous
+silicon-on-insulator (SOI) platform. We grow epitaxial, single-crystalline
+BaTiO3 directly on SOI and engineer integrated waveguide structures that
+simultaneously confine light and an RF electric field in the BaTiO3 layer.
+Using on-chip photonic interferometers, we extract a large effective Pockels
+coefficient of 213 plus minus 49 pm/V, a value more than six times larger than
+found in commercial optical modulators based on lithium niobate. The
+monolithically integrated BaTiO3 optical modulators show modulation bandwidth
+in the gigahertz regime, which is promising for broadband applications.",1401.4184v2
+2014-02-22,Ab initio quantum Monte Carlo calculations of spin superexchange in cuprates: the benchmarking case of Ca$_2$CuO$_3$,"In view of the continuous theoretical efforts aimed at an accurate
+microscopic description of the strongly correlated transition metal oxides and
+related materials, we show that with continuum quantum Monte Carlo (QMC)
+calculations it is possible to obtain the value of the spin superexchange
+coupling constant of a copper oxide in a quantitatively excellent agreement
+with experiment. The variational nature of the QMC total energy allows us to
+identify the best trial wave function out of the available pool of wave
+functions, which makes the approach essentially free from adjustable parameters
+and thus truly ab initio. The present results on magnetic interactions suggest
+that QMC is capable of accurately describing ground state properties of
+strongly correlated materials.",1402.5561v2
+2014-02-25,"Double perovskite heterostructures: Magnetism, Chern bands, and Chern insulators","Experiments demonstrating the controlled growth of oxide heterostructures
+have raised the prospect of realizing topologically nontrivial states of
+correlated electrons in low dimensions. Here, we study heterostructures
+consisting of {111}-bilayers of double perovskites separated by inert band
+insulators. In bulk, these double perovskites have well-defined local moments
+interacting with itinerant electrons leading to high temperature
+ferromagnetism. Incorporating spin-orbit coupling in the two-dimensional
+honeycomb geometry of a {111}-bilayer, we find a rich phase diagram with
+tunable ferromagnetic order, topological Chern bands, and a C=2 Chern insulator
+regime. An effective two-band model of Zeeman-split j=3/2 states captures this
+nontrivial band topology. Our results are of broad relevance to oxide materials
+such as Sr2FeMoO6, Ba2FeReO6, and Sr2CrWO6.",1402.6347v4
+2014-04-21,Wide-angle energy-momentum spectroscopy,"Light emission is defined by its distribution in energy, momentum, and
+polarization. Here, we demonstrate a method that resolves these distributions
+by means of wide-angle energy-momentum spectroscopy. Specifically, we image the
+back focal plane of a microscope objective through a Wollaston prism to obtain
+polarized Fourier-space momentum distributions, and disperse these
+two-dimensional radiation patterns through an imaging spectrograph without an
+entrance slit. The resulting measurements represent a convolution of individual
+radiation patterns at adjacent wavelengths, which can be readily deconvolved
+using any well-defined basis for light emission. As an illustrative example, we
+use this technique with the multipole basis to quantify the intrinsic emission
+rates for electric and magnetic dipole transitions in europium-doped yttrium
+oxide (Eu$^{3+}$:Y$_{2}$O$_{3}$) and chromium-doped magnesium oxide
+(Cr$^{3+}$:MgO). Once extracted, these rates allow us to reconstruct the full,
+polarized, two-dimensional radiation patterns at each wavelength.",1404.5109v1
+2014-09-01,Imaging and Control of Ferromagnetism in a Polar Antiferromagnet,"Atomically sharp oxide heterostructures often exhibit unusual physical
+properties that are absent in the constituent bulk materials. The interplay
+between electrostatic boundary conditions, strain and dimensionality in
+ultrathin epitaxial films can result in monolayer-scale transitions in
+electronic or magnetic properties. Here we report an atomically sharp
+antiferromagnetic-to-ferromagnetic phase transition when atomically growing
+polar antiferromagnetic LaMnO3 (001) films on SrTiO3 substrates. For a
+thickness of five unit cells or less, the films are antiferromagnetic, but for
+six unit cells or more, the LaMnO3 film undergoes a phase transition to a
+ferromagnetic state over its entire area, which is visualized by scanning
+superconducting quantum interference device microscopy. The transition is
+explained in terms of electronic reconstruction originating from the polar
+nature of the LaMnO3 (001) films. Our results demonstrate how new emergent
+functionalities can be visualized and engineered in atomically thick oxide
+films at the atomic level.",1409.0520v1
+2014-09-18,Electronic and magnetic properties of Ti4O7 predicted by self-interaction corrected density functional theory,"Understanding electronic properties of sub-stoichiometric phases of titanium
+oxide such as Magn\'eli phase Ti4O7 is crucial in designing and modeling
+resistive switching devices. Here we present our study on Magn\'eli phase Ti4O7
+together with rutile TiO2 and Ti2O3 using density functional theory methods
+with atomic-orbital-based self-interaction correction (ASIC). We predict a new
+antiferromagnetic ground state in the low temperature phase (or LT phase), and
+we explain energy difference with a competing antiferromagnetic state using a
+Heisenberg model. The predicted energy ordering of these states in the LT phase
+is calculated to be robust in a wide range of modeled isotropic strain. We have
+also investigated the dependence of the electronic structures of the Ti-O
+phases on stoichiometry. The splitting of titanium t2g orbitals is enhanced
+with increasing oxygen deficiency as Ti-O is reduced. The electronic properties
+of all these phases can be reasonably well described by applying ASIC with a
+standard value for transition metal oxides of the empirical parameter {\alpha}
+of 0.5 representing the magnitude of the applied self-interaction correction.",1409.5331v2
+2014-10-08,Transport properties of beta-Ga2O3 Nanoparticles embedded in Nb thin films,"The origin of ferromagnetism in nanoparticles of nonmagnetic oxides is an
+interesting area of research. In the present work, transport properties of
+niobium thin films, with beta-Ga2O3 nanoparticles embedded within them, are
+presented. Nanoparticles of beta-Ga2O3 embedded in a Nb matrix were prepared at
+room temperature by radio frequency co-sputtering technique on Si (100) and
+glass substrates held at room temperature. The thin films deposited on Si
+substrates were subjected to Ar annealing at a temperature range of 600-650 C
+for 1 hour. Films were characterized by X-ray diffraction (XRD), Micro-Raman
+and elemental identification was performed with an Energy Dispersive X-ray
+Spectroscopy (EDS). Transport measurements were performed down to liquid helium
+temperatures by four-probe contact technique, showed characteristics analogous
+to those observed in the context of a Kondo system. A comparison of the
+experimental data with the theoretical formalism of Kondo and Hamann is
+presented. It is suggested that this behavior arises from the existence of
+magnetic moments associated with the oxygen vacancy defects in the
+nanoparticles of the nonmagnetic oxide Ga2O3.",1410.2047v1
+2014-11-22,Large voltage-induced modification of spin-orbit torques in Pt/Co/GdOx,"We report on large modifications of current-induced spin-orbit torques in a
+gated Pt/Co/Gd-oxide microstrip due to voltage-driven O$^{2-}$ migration. The
+Slonczewski-like and field-like torques are quantified using a low-frequency
+harmonic technique based on the polar magneto-optical Kerr effect.
+Voltage-induced oxidation of Co enhances the Slonczewski-like torque by as much
+as an order of magnitude, and simultaneously reduces the anisotropy energy
+barrier by a factor of ~5. Such magneto-ionic tuning of interfacial spin-orbit
+effects may significantly enhance the efficiency of magnetization switching and
+provide additional degrees of freedom in spintronic devices.",1411.6153v1
+2014-11-24,Kitaev magnetism in honeycomb RuCl3 with intermediate spin-orbit coupling,"Intensive studies of the interplay between spin-orbit coupling (SOC) and
+electronic correlations in transition metal compounds have recently been
+undertaken. In particular, $j_{\rm eff}$ = 1/2 bands on a honeycomb lattice
+provide a pathway to realize Kitaev's exactly solvable spin model. However,
+since current wisdom requires strong atomic SOC to make $j_{\rm eff}=1/2$
+bands, studies have been limited to iridium oxides. Contrary to this
+expectation, we demonstrate how Kitaev interactions arise in 4$d$-orbital
+honeycomb $\alpha$-RuCl$_3$, despite having significantly weaker SOC than the
+iridium oxides, via assistance from electron correlations. A strong coupling
+spin model for these correlation-assisted $j_{\rm eff}$ = 1/2 bands is derived,
+in which large antiferromagnetic Kitaev interactions emerge along with
+ferromagnetic Heisenberg interactions. Our analyses suggest that the ground
+state is a zigzag-ordered phase lying close to the antiferromagnetic Kitaev
+spin liquid. Experimental implications for angle resolved photoemission
+spectroscopy, neutron scattering, and optical conductivities are discussed.",1411.6623v3
+2015-01-08,Using ultrashort optical pulses to couple ferroelectric and ferromagnetic order in an oxide heterostructure,"A new approach to all-optical detection and control of the coupling between
+electric and magnetic order on ultrafast timescales is achieved using
+time-resolved second harmonic generation (SHG) to study a ferroelectric
+(FE)/ferromagnet (FM) oxide heterostructure. We use femtosecond optical pulses
+to modify the spin alignment in a
+Ba$_{0.1}$Sr$_{0.9}$TiO$_{3}$(BSTO)/La$_{0.7}$Ca$_{0.3}$MnO$_{3}$ (LCMO)
+heterostructure and selectively probe the ferroelectric response using SHG. In
+this heterostructure, the pump pulses photoexcite non-equilibrium
+quasiparticles in LCMO, which rapidly interact with phonons before undergoing
+spin-lattice relaxation on a timescale of tens of picoseconds. This reduces the
+spin-spin interactions in LCMO, applying stress on BSTO through
+magnetostriction. This then modifies the FE polarization through the
+piezoelectric effect, on a timescale much faster than laser-induced heat
+diffusion from LCMO to BSTO. We have thus demonstrated an ultrafast indirect
+magnetoelectric effect in a FE/FM heterostructure mediated through elastic
+coupling, with a timescale primarily governed by spin-lattice relaxation in the
+FM layer.",1501.01753v1
+2015-02-26,Possible mechanisms of electronic phase separation in oxide interfaces,"LaAlO3/SrTiO3 ad LaTiO3/SrTiO3 interfaces are known to host a strongly
+inhomogeneous (nearly) two-dimensional electron gas (2DEG). In this work we
+present three unconventional electronic mechanisms of electronic phase
+separation (EPS) in a 2DEG as a possible source of inhomogeneity in oxide
+interfaces. Common to all three mechanisms is the dependence of some
+(interaction) potential on the 2DEG's density. We first consider a mechanism
+resulting from a sizable density-dependent Rashba spin-orbit coupling. Next, we
+point out that an EPS may also occur in the case of a density-dependent
+superconducting pairing interaction. Finally, we show that the confinement of
+the 2DEG to the interface by a density-dependent, self-consistent electrostatic
+potential can by itself cause an EPS.",1502.07561v1
+2015-03-02,Nanostructural features degrading the performance of superconducting radio frequency niobium cavities revealed by TEM and EELS,"Nanoscale defect structure within the magnetic penetration depth of ~100nm is
+key to the performance limitations of niobium superconducting radio frequency
+(SRF) cavities. Using a unique combination of advanced thermometry during
+cavity RF measurements, and TEM structural and compositional characterization
+of the samples extracted from cavity walls, we discover the existence of
+nanoscale hydrides in electropolished cavities limited by the high field Q
+slope, and show the decreased hydride formation in the electropolished cavity
+after 120C baking. Furthermore, we demonstrate that adding 800C hydrogen
+degassing followed by light buffered chemical polishing restores the hydride
+formation to the pre-120C bake level. We also show absence of niobium oxides
+along the grain boundaries and the modifications of the surface oxide upon 120C
+bake.",1503.02046v2
+2015-06-01,Negative Magnetoresistance in Amorphous Indium Oxide Wires,"We study magneto-transport properties of several amorphous Indium oxide
+nanowires of different widths. The wires show superconducting transition at
+zero magnetic field, but, there exist a finite resistance at the lowest
+temperature. The $R(T)$ broadening was explained by available phase slip
+models. At low field, and far below the superconducting critical temperature,
+the wires with diameter equal to or less than 100 nm, show negative
+magnetoresistance (nMR). The magnitude of nMR and the crossover field are found
+to be dependent on both temperature and the cross-sectional area. We find that
+this intriguing behavior originates from the interplay between two field
+dependent contributions.",1506.00459v3
+2015-06-08,A compact plasmonic MOS-based 2x2 electro-optic switch,"We report on a three-waveguide electro-optic switch for compact photonic
+integrated circuits and data routing applications. The device features a
+plasmonic metal-oxide-semiconductor (MOS) mode for enhanced
+light-matter-interactions. The switching mechanism originates from a
+capacitor-like design where the refractive index of the active medium,
+Indium-Tin-Oxide, is altered via shifting the plasma frequency due to carrier
+accumulation inside the waveguide-based MOS structure. This light manipulation
+mechanism controls the transmission direction of transverse magnetic polarized
+light into either a CROSS or BAR waveguide port. The extinction ratio of 18 dB
+(7) dB for the CROSS (BAR) state, respectively, is achieved via a gating
+voltage bias. The ultrafast broadband fJ/bit device allows for seamless
+integration with Siliconon- Insulator platforms to for low-cost manufacturing.",1506.02337v1
+2015-07-10,Jahn-Teller distortions as a novel source of multiferroicity,"The Jahn-Teller effect is a fascinating and ubiquitous phenomenon in modern
+quantum physics and chemistry. We propose a class of oxides with melilite
+structure Ba$_2$TGe$_2$O$_7$ (T=V,Ni) where Jahn-Teller distortions are the
+main responsibles for the appearance of electric polarization. At the hearth of
+the proposed mechanism lies the lack of inversion symmetry displayed by
+tetrahedrally coordinated transition-metal ions, which allows for the
+condensation of polar Jahn-Teller distortions, at odds with octahedral
+coordination typical of conventional ferroelectric oxides with perovskite
+structure. Since the noncentrosymmetric local environment of transition-metal
+ions also activates the proposed spin-dependent hybridization mechanism for
+magnetically-induced electric polarization, proper multiferroic phases with
+intrinsic magnetoelectric interaction could be realized in this class of
+low-symmetry materials.",1507.02810v1
+2015-07-18,Two step solid state synthesis and Synchrotron X-ray characterizations of ceramic Co3TeO6; an improper multiferroic,"A two step solid state reaction route has been presented to synthesize
+monophasic cobalt tellurate (Co3TeO6, CTO) using Co3O4 and TeO2 as starting
+reagents. During synthesis, initial ingredient Co3O4 is found better than CoO
+in circumventing the intermediate Co5TeO8 or CoTeO3 phases. High resolution
+Synchrotron X-ray Diffraction has been used to probe different phases present
+in synthesized CTO and to achieve its single phase. Further, XANES studies near
+Co K and Te L-edge reveal mixed oxidation states of Co (i.e. Co2+ and Co3+) and
++VI valence state of Te respectively, which is also confirmed with XPS. Charge
+imbalance due to different oxidation states of the Co-ions has been observed to
+be compensated by plausible Te-cations vacancy. Enhanced multiferroic
+properties like effective magnetic moment (JAP 116, (2014)) have been
+correlated with the present synthesis route.",1507.05190v1
+2016-03-11,Novel Charge Ordering in the Trimer Iridium Oxide BaIrO3,"We have prepared polycrystalline samples of the trimer Ir oxide BaIrO3 with
+face-shared Ir3O12 trimers, and have investigated the origin of the phase
+transition at 182 K by measuring resistivity, thermopower, magnetization and
+synchrotron x-ray diffraction. We propose a possible electronic model and
+transition mechanism, starting from a localized electron picture on the basis
+of the Rietveld refinement. Within this model, BaIrO3 can be basically regarded
+as a Mott insulator, when the Ir3O12 trimer is identified to one pseudo-atom or
+one lattice site. The transition can be viewed as a transition from the Mott
+insulator phase to a kind of charge ordered insulator phase.",1603.03525v1
+2016-03-17,Reconciling the ionic and covalent pictures in rare-earth nickelates,"The properties of AMO3 perovskite oxides, where M is a 3d transition metal,
+depend strongly on the level of covalency between the metal d and oxygen p
+orbitals. With their complex spin orders and metal-insulator transition,
+rare-earth nickelates verge between dominantly ionic and covalent characters.
+Accordingly, the nature of their ground state is highly debated. Here, we
+reconcile the ionic and covalent visions of the insulating state of nickelates.
+Through first-principles calculations, we show that it is reminiscent of the
+ionic charge disproportionation picture (with strictly low-spin 4+ and
+high-spin 2+ Ni sites) while exhibiting strong covalence effects with oxygen
+electrons shifted toward the depleted Ni cations, mimicking a configuration
+with identical Ni sites. Our results further hint at strategies to control
+electronic and magnetic phases of transition metal oxide perovskites.",1603.05480v1
+2016-09-07,Emerging magnetism and anomalous Hall effect in iridate-manganite heterostructures,"Strong Coulomb repulsion and spin-orbit coupling are known to give rise to
+exotic physical phenomena in transition metal oxides. Initial attempts to
+investigate systems where both of these fundamental interactions are comparably
+strong, such as 3d and 5d complex oxide superlattices, have revealed properties
+that only slightly differ from the bulk ones of the constituent materials.
+Here, we observe that the interfacial coupling between the 3d antiferromagnetic
+insulator SrMnO3 and the 5d paramagnetic metal SrIrO3 is enormously strong,
+yielding an anomalous Hall response as the result of charge transfer driven
+interfacial ferromagnetism. These findings show that low dimensional spin-orbit
+entangled 3d-5d interfaces provide an avenue to uncover technologically
+relevant physical phenomena unattainable in bulk materials.",1609.01973v1
+2016-09-12,Estimation of spin relaxation lengths in spin valves of In and In2O3 nanostructures,"We report the electrical injection and detection of spin polarized current in
+lateral ferromagnet-nonmagnet-ferromagnet spin valve devices, ferromagnet being
+cobalt and nonmagnet being indium (In) or indium oxide (In2O3) nanostructures.
+The In nanostructures were grown by depositing pure In on lithographically
+pre-patterned structures. In2O3 nanostructures were obtained by oxidation of In
+nanostructures. Spin valve devices were fabricated by depositing micro magnets
+over the nanostructures with connecting nonmagnetic electrodes via two steps of
+e-beam lithography. Clear spin switching behavior was observed in the both
+types of spin valve devices measured at 10 K. From the measured spin signal,
+the spin relaxation length ({\lambda}N) of In and In2O3 nanostructures were
+estimated to be 449.6 nm and 788.6 nm respectively.",1609.03609v1
+2016-09-20,Observation of Inverse Edelstein Effect in Rashba-Split 2DEG between SrTiO3 and LaAlO3 at Room Temperature,"The Rashba physics has been intensively studied in the field of spin
+orbitronics, for the purpose of searching novel physical properties and the FM
+magnetization switching for technology applications. Here, we report the
+observation of the inverse Edelstein effect up to room temperature in the
+Rashba-split 2DEG between two insulating oxides SrTiO3 and LaAlO3 with the
+LaAlO3 layer thickness from 3 to 40 unit cells (UC). We further demonstrate
+that the spin voltage could be dramatically manipulated by electric field
+effect for the 2DEG between SrTiO3 and 3 UC LaAlO3. These results demonstrate
+that the Rashba-split 2DEG at the complex oxide interface can be used for room
+temperature efficient charge-and-spin conversion for the generation and
+detection of spin current.",1609.06207v2
+2016-09-23,Emergent ultrafast phenomena in correlated oxides and heterostructures,"The possibility of investigating the dynamics of solids on timescales faster
+than the thermalization of the internal degrees of freedom has disclosed novel
+non-equilibrium phenomena that have no counterpart at equilibrium. Transition
+metal oxides (TMOs) provide an interesting playground in which the correlations
+among the charges in the metal $d$-orbitals give rise to a wealth of intriguing
+electronic and thermodynamic properties involving the spin, charge, lattice and
+orbital orders. Furthermore, the physical properties of TMOs can be engineered
+at the atomic level, thus providing the platform to investigate the transport
+phenomena on timescales of the order of the intrinsic decoherence time of the
+charge excitations.
+  Here, we review and discuss three paradigmatic examples of transient emerging
+properties that are expected to open new fields of research: i) the creation of
+non-thermal magnetic states in spin-orbit Mott insulators; ii) the possible
+exploitation of quantum paths for the transport and collection of charge
+excitations in TMO-based few-monolayers devices; iii) the transient wave-like
+behavior of the temperature field in strongly anisotropic TMOs.",1609.07394v1
+2017-03-03,A high-temperature superconducting weak-link defined by ferroelectric field-effect,"In all-oxide ferroelectric (FE) - superconductor (S) bilayers, due to the low
+carrier concentration of oxides compared to transition metals, the FE
+interfacial polarization charges induce an accumulation (or depletion) of
+charge carriers in the S. This leads either to an enhancement or a depression
+of its critical temperature depending on FE polarization direction.Here we
+exploit this effect at a local scale to define planar weak-links in
+high-temperature superconducting wires. This is realized in
+BiFeO3(FE)/YBa2Cu3O7(S)bilayers in which the remnant FE domain structure is
+written at will by locally applying voltage pulses with a conductive-tip atomic
+force microscope. In this fashion, the FE domain pattern defines a spatial
+modulation of superconductivity. This allows us to write a device whose
+electrical transport shows different temperature regimes and magnetic field
+matching effects that are characteristic of Josephson coupled weak-links. This
+illustrates the potential of the ferroelectric approach for the realization of
+high-temperature superconducting devices.",1703.01219v1
+2017-08-21,Spin-orbit coupling in three-orbital Kanamori impurity model and its relevance for transition-metal oxides,"We investigate the effects of the spin-orbit coupling (SOC) in a
+three-orbital impurity model with Kanamori interaction using the numerical
+renormalization group method. We focus on the impurity occupancy $N_d=2$
+relevant to the dynamical mean-field theory studies of Hund's metals. Depending
+on the strength of SOC $\lambda$ we identify three regimes: usual Hund's
+impurity for $|\lambda|<\lambda_c$, van-Vleck non-magnetic impurity for
+$\lambda > \lambda_c$, and a $J=2$ impurity for $\lambda < -\lambda_c$. They
+all correspond to a Fermi liquid but with very different quasiparticle phase
+shifts and different physical properties. The crossover between these regimes
+is controlled by an emergent scale, the orbital Kondo temperature, $\lambda_c
+=T_K^\mathrm{orb}$ that drops with increasing interaction strength. This
+implies that oxides with strong electronic correlations are more prone to the
+effects of the spin-orbit coupling.",1708.06089v1
+2017-08-28,Dependence of Dzyaloshinskii-Moriya interaction on the oxygen coverage in Pt/Co/MOx trilayers,"We have studied the interfacial Dzyaloshinskii-Moriya interaction (DMI) in a
+series of Pt/Co/MOx (M=Al, Gd) trilayers in which the degree of oxidation of
+the top Co interface is varied. To access to reliable values of the DMI
+strength, we have used a method based on the measurement of the saturation
+velocity of field driven chiral N\'eel domain walls. We show that the effective
+DMI strength in the Pt/Co/MOx trilayers varies with the oxidation degree of the
+Co/MOx interface. This strongly suggests that the Co/MOx interface gives a
+distinct contribution to the total DMI, adding to that of the Pt/Co interface.
+The DMI presents a maximum for the oxygen coverage maximizing also the
+interface magnetic anisotropy energy Ks. This calls for common microscopic
+origins for the contributions of the Co/MOx interface to DMI and Ks.",1708.08516v1
+2018-04-11,Computational study on the half-metallicity in transition metal-oxide-incorporated 2D g-C3N4 nanosheets,"In this study, based on the first-principles calculations, we systematically
+investigated the electronic and magnetic properties of the transition
+metal-oxide-incorporated 2D g-C3N4 nanosheet (labeled C3N4-TM-O, TM = Sc-Mn).
+The results suggest that the TM-O binds to g-C3N4 nanosheets strongly for all
+systems. We found that the 2D C3N4-TM-O framework is ferromagnetic for TM = Sc,
+Ti, V, Cr, while it is antiferromagnetic for TM = Mn. All the ferromagnetic
+systems exhibit the half-metallic property. Furthermore, Monte Carlo
+simulations based on the Heisenberg model suggest that the Curie temperatures
+(T_c) of the C3N4-TM-O (TM = Sc, Ti, V, Cr) framework are 169 K, 68 K, 203 K,
+and 190 K, respectively. Based on Bader charge analysis, we found that the
+origin of the half-metallicity at Fermi energy can be partially attributed to
+the transfer of electrons from TM atoms to the g-C3N4 nanosheet. In addition,
+we found that not only electrons but also holes can induce half-metallicity for
+2D g-C3N4 nanosheets, which may help to understand the origin of
+half-metallicity for graphitic carbon nitride.",1804.03779v1
+2018-04-30,Magneto-Stark-effect of yellow excitons in cuprous oxide,"We investigate and compare experimental and numerical excitonic spectra of
+the yellow series in cuprous oxide Cu$_2$O in the Voigt configuration and thus
+partially extend the results from Schweiner et al. [Phys. Rev. B 95, 035202
+(2017)], who only considered the Faraday configuration. The main difference
+between the configurations is given by an additional effective electric field
+in the Voigt configuration, caused by the motion of the exciton through the
+magnetic field. This Magneto-Stark effect was already postulated by Gross et
+al. and Thomas et al. in 1961 [Sov. Phys. Solid State 3, 221 (1961); Phys. Rev.
+124, 657 (1961)]. Group theoretical considerations show that the field most of
+all significantly increases the number of allowed lines by decreasing the
+symmetry of the system. This conclusion is supported by both the experimental
+and numerical data.",1804.11093v3
+2019-05-23,Interface ferromagnetism and anomalous Hall effect of CdO/ferromagnetic insulator heterostructures,"The experimental observation of quantum anomalous Hall effect (QAHE) in
+magnetic topological insulators has stimulated enormous interest in
+condensed-matter physics and materials science. For the purpose of realizing
+high-temperature QAHE, several material candidates have been proposed, among
+which the interface states in the CdO/ferromagnetic insulator heterostructures
+are particularly interesting and favorable for technological applications.
+Here, we report the experimental observation of the interfacial ferromagnetism
+and anomalous Hall effect in the Fe3O4/CdO/Fe3O4 heterostructures grown via
+oxide molecular-beam epitaxy. Systematical variation of the CdO thickness
+reveals the interface ferromagnetism as the major cause for the observed planar
+magnetoresistance and anomalous Hall effect. Our results might pave the way to
+engineer oxide interface states for the exploration of QAHE towards exotic
+quantum-physical phenomena and potential applications.",1905.09425v1
+2010-05-04,NMR evidence for antiferromagnetic order in a planar 3d9/3d8 nickelate,"We report La-139 Nuclear Magnetic Resonance (NMR) data in La4Ni3O8 which
+reveals the presence of antiferromagnetic order below T_N ~ 105 K. This
+compound contains two-dimensional layers of NiO2 that are isostructural to the
+copper oxide planes of the high temperature superconductors. This compound is
+remarkable because the average Ni valence of 1.33+ for formally 2Ni1+ + Ni2+
+indicates a 3d9/3d8 electronic configuration. Nickel oxides with Ni1+ valence
+are rare and unstable, yet may provide new routes to high temperature
+superconductivity. La4Ni3O8, with antiferromagnetic order of S=1/2 Ni1+ spins,
+is analogous to the parent compounds of the cuprate superconductors. Our data
+clearly reveal dramatic spectral changes and low energy antiferromagnetic
+correlations associated with the onset of long range order below T_N.",1005.0435v1
+2010-05-18,Apical oxygens and correlation strength in electron and hole doped copper oxides,"We use the Local Density Approximation in combination with the Dynamical Mean
+Field Theory to carry out a comparative investigation of a typical electron
+doped and a typical hole doped copper oxide, NCCO and LSCO respectively. The
+parent compounds of both materials are strongly correlated electron systems in
+the vicinity of the metal to charge transfer insulator transition. In NCCO the
+magnetic long range order is essential to open a charge transfer gap, while
+Mott physics is responsible for the gap in LSCO. We highlights the role of the
+apical oxygens in determining the strength of the correlations and obtaining
+overall good agreement between theory and several experimentally determined
+quantities. Results for optical conductivity, polarized X-ray absorption and
+angle resolved photoemission are presented and compared with experiments.",1005.3100v1
+2017-01-27,Thickness dependent properties in oxide heterostructures driven by structurally induced metal-oxygen hybridization variations,"Thickness driven electronic phase transitions are broadly observed in
+different types of functional perovskite heterostructures. However, uncertainty
+remains whether these effects are solely due to spatial confinement, broken
+symmetry or rather to a change of structure with varying film thickness. Here,
+we present direct evidence for the relaxation of oxygen 2p and Mn 3d orbital
+(p-d) hybridization coupled to the layer dependent octahedral tilts within a
+La2/3Sr1/3MnO3 film driven by interfacial octahedral coupling. An enhanced
+Curie temperature is achieved by reducing the octahedral tilting via interface
+structure engineering. Atomically resolved lattice, electronic and magnetic
+structures together with X-ray absorption spectroscopy demonstrate the central
+role of thickness dependent p-d hybridization in the widely observed
+dimensionality effects present in correlated oxide heterostructures.",1701.07930v1
+2017-01-27,Low-energy excitation spectra in the excitonic phase of cobalt oxides,"We study the excitonic phase and low-energy excitation spectra of perovskite
+cobalt oxides. Constructing the five-orbital Hubbard model defined on the
+three-dimensional cubic lattice for the $3d$ bands of
+Pr$_{0.5}$Ca$_{0.5}$CoO$_3$, we calculate the excitonic susceptibility in the
+normal state in the random-phase approximation (RPA) to show the presence of
+the instability toward excitonic condensation. Based on the excitonic ground
+state with a magnetic multipole obtained in the mean-field approximation, we
+calculate the dynamical susceptibility of the excitonic phase in the RPA and
+find that there appear the gapless collective excitation in the spin-transverse
+mode (Goldstone mode) and the gapful collective excitation in the
+spin-longitudinal mode (Higgs mode). Experimental relevance is discussed.",1701.07943v3
+2018-05-08,Understanding LiOH Chemistry in a Ruthenium Catalyzed Li-O2 Battery,"Non-aqueous Li-O2 batteries are promising for next generation energy storage.
+New battery chemistries based on LiOH, rather than Li2O2, have recently been
+reported in systems with added water, one using a soluble additive LiI and the
+other using solid Ru catalysts. Here, we focus on the mechanism of Ru-catalyzed
+LiOH chemistry. Using nuclear magnetic resonance, operando electrochemical
+pressure measurements and mass spectrometry, we show that on discharging LiOH
+forms via a 4 e- oxygen reduction reaction, the H in LiOH coming solely from
+added H2O and the O from both O2 and H2O. On charging, quantitative LiOH
+oxidation occurs at 3.1 V, with O being trapped in a form of dimethyl sulfone
+in the electrolyte. Compared to Li2O2, LiOH formation over Ru incurs hardly any
+side reactions, a critical advantage for developing a long-lived battery. An
+optimized metal catalyst-electrolyte couple needs to be sought that aids LiOH
+oxidation and is able stable towards attack by hydroxyl radicals.",1805.03268v1
+2018-05-16,Quantum well structure of a double perovskite superlattice and formation of a spin-polarized two-dimensional electron gas,"Layered oxide heterostructures are the new routes to tailor desired
+electronic and magnetic phases emerging from competing interactions involving
+strong correlation, orbital hopping, tunnelling and lattice coupling phenomena.
+Here, we propose a half-metal/insulator superlattice that intrinsically forms
+spin-polarized two-dimensional electron gas (2DEG) following a mechanism very
+different from the widely reported 2DEG at the single perovskite polar
+interfaces. From DFT$+U$ study on Sr$_2$FeMoO$_6$/La$_2$CoMnO$_6$ (001)
+superlattice, we find that a periodic quantum well is created along [001] which
+breaks the three-fold $t_{2g}$ degeneracy to separate the doubly degenerate
+$xz$ and $yz$ states from the planar $xy$ state. In the spin-down channel, the
+dual effect of quantum confinement and strong correlation localizes the
+degenerate states, whereas the dispersive $xy$ state forms the 2DEG which is
+robust against perturbations to the superlattice symmetry. The spin-up channel
+retains the bulk insulating. Both spin polarization and orbital polarization
+make the superlattice ideal for spintronic and orbitronic applications. The
+suggested 2DEG mechanism widens the scope of fabricating next generation of
+oxide heterostructures.",1805.06128v2
+2018-05-06,Alkoxide-intercalated NiFe-layered double hydroxides magnetic nanosheets as efficient water oxidation electrocatalysts,"Alkoxide-intercalated NiFe-layered double hydroxides were synthesized via the
+nonaqueous methanolic route. These nanoplatelets exhibit high crystalline
+quality as demonstrated by atomic resolution scanning transmission electron
+microscopy combined with electron energy-loss spectroscopy. Moreover, the
+presence of the alkoxide moieties has been unambiguously demonstrated by means
+of thermogravimetric analysis coupled to a mass spectrometer. These NiFe-LDHs
+can be exfoliated in water or organic solvents and processed into homogeneous
+ultra-thin films (< 3nm thick) with the assistance of O2-plasma. The study of
+their behaviour as water oxidation electrocatalysts has shown an outstanding
+performance at basic pHs (small overpotential of ca. 249 mV and Tafel slopes in
+the range of 52-55 mV per decade).",1805.11668v1
+2009-12-23,The effect of anomalous adsorption of H2O and CO2 by pre-hydrated YBa_2Cu_3O_{6.53},"The results of a comprehensive study on the YBa_2Cu_3O_{6.53} oxide subjected
+to ""mild"" hydration (exposure at small values of pH2O) by a special technique
+have been reported. The material modified in this way acquires an interesting
+property; namely, in natural conditions it intensively absorbs large quantities
+of components (H2O and CO2) comprising the gas atmosphere. Arguments have been
+adduced that at least the water enters the crystal lattice of the
+yttrium-barium cuprate. This lattice is in the two-phase (tetragonal and
+orthorhombic) state: testing of the magnetic properties of the oxide has
+revealed the presence of antiferromagnetic and diamagnetic regions in this
+material.",0912.4601v1
+2012-04-11,The structural and electronic properties of tin oxide nanowires: an {\it ab initio} investigation,"We performed an {\it ab initio} investigation on the properties of rutile tin
+oxide (SnO$_{x}$) nanowires. We computed the wire properties determining the
+equilibrium geometries, binding energies and electronic band structures for
+several wire dimensions and surface facet configurations. The results allowed
+to establish scaling laws for the structural properties, in terms of the
+nanowire perimeters. The results also showed that the surface states control
+most of the electronic properties of the nanowires. Oxygen incorporation in the
+nanowire surfaces passivated the surface-related electronic states, and the
+resulting quantum properties and scaling laws were fully consistent with
+electrons confined inside the nanowire. Additionally, oxygen incorporation in
+the wire surfaces generated an unbalanced concentration of spin up and down
+electrons, leading to magnetic states for the nanowires.",1204.2534v1
+2015-12-01,Erosion behaviour of composite Al-Cr cathodes in cathodic arc plasmas in inert and reactive atmospheres,"Al$_{x}$Cr$_{1-x}$ composite cathodes with Al contents of x = 0.75, 0.5 and
+0.25 were exposed to cathodic arc plasmas in Ar, N$_2$ and O$_2$ atmospheres
+and their erosion behaviour was studied. Cross-sectional analysis of the
+elemental distribution of the near-surface zone in the cathodes by scanning
+electron microscopy revealed the formation of a modified layer for all cathodes
+and atmospheres. Due to intermixing of Al and Cr in the heat-affected zone,
+intermetallic Al-Cr phases formed as evidenced by X-ray diffraction analysis.
+Cathode poisoning effects in the reactive N$_2$ and O$_2$ atmospheres were
+non-uniform as a result of the applied magnetic field configuration. With the
+exception of oxide islands on Al-rich cathodes, reactive layers were absent in
+the circular erosion zone, while nitrides and oxides formed in the less eroded
+centre region of the cathodes.",1512.00332v2
+2018-10-24,Electronic landscape of the P-cluster of nitrogenase as revealed through many-electron quantum wavefunctions,"The electronic structure of the nitrogenase metal cofactors is central to
+nitrogen fixation. However, the P-cluster and iron molybdenum cofactor, each
+containing eight irons, have resisted detailed characterization of their
+electronic properties. Through exhaustive many-electron wavefunction
+simulations enabled by new theoretical methods, we report on the low-energy
+electronic states of the P-cluster in three oxidation states. The energy scales
+of orbital and spin excitations overlap, yielding a dense spectrum with
+features we trace to the underlying atomic states and recouplings. The clusters
+exist in superpositions of spin configurations with non-classical spin
+correlations, complicating interpretation of magnetic spectroscopies, while the
+charges are mostly localized from reorganization of the cluster and its
+surroundings. Upon oxidation, the opening of the P-cluster significantly
+increases the density of states, which is intriguing given its proposed role in
+electron transfer. These results demonstrate that many-electron simulations
+stand to provide new insights into the electronic structure of the nitrogenase
+cofactors.",1810.10196v2
+2018-10-24,A systematic study of the local minima in L(S)DA+U,"We have performed a systematic study of the emergence of meta-stable states
+in density functional theory plus Hubbard U (DFT+U ) simulations of NiO, CoO,
+FeO. Particular attention is given to the spin-polarization of the
+exchange-correlation functional and the double counting term, and the role of
+the spin-orbit coupling. The method of occupation matrix control is extended to
+use constrained random density matrices to map out the local minima in the
+total energy landscape. The extended scheme, random density matrix control, is
+successfully benchmarked against UO2, one of the most investigated systems in
+the field. When applied to the transition metal oxides it yields several meta-
+stable states which are well-characterized by their local spin and orbital
+moments. We find that the addition of spin-orbit coupling helps the simulations
+to converge to the global high-spin energy minimum. The random density matrix
+control scheme combined with LDA+U yields accurate magnetic moments for all the
+studied AFM transition metal oxides.",1810.10393v1
+2021-01-24,Electronic structure and transport properties of sol-gel-derived high-entropy Ba(Zr0.2Sn0.2Ti0.2Hf0.2Nb0.2)O3 thin films,"High-entropy perovskite thin films, as the prototypical representative of the
+high-entropy oxides with novel electrical and magnetic features, have recently
+attracted great attention. Here, we reported the electronic structure and
+charge transport properties of sol-gel-derived high-entropy
+Ba(Zr0.2Sn0.2Ti0.2Hf0.2Nb0.2)O3 thin films annealed at various temperatures. By
+means of X-ray photoelectron spectroscopy and absorption spectrum, it is found
+that the conduction-band-minimum shifts downward and the valence-band-maximum
+shifts upward with the increase of annealing temperature, leading to the
+narrowed band gap. Electrical resistance measurements confirmed a
+semiconductor-like behavior for all the thin films. Two charge transport
+mechanisms, i.e., the thermally-activated transport mechanism at high
+temperatures and the activation-less transport mechanism at low temperatures,
+are identified by a self-consistent analysis method. These findings provide a
+critical insight into the electronic band structure and charge transport
+behavior of Ba(Zr0.2Sn0.2Ti0.2Hf0.2Nb0.2)O3, validating it as a compelling
+high-entropy oxide material for future electronic/energy-related technologies.",2101.09633v2
+2017-09-11,Tuning electrical properties of silicon dioxide through intrinsic nano-patterns,"The inherent network of nanopores and voids in silicon dioxide (SiO2) is
+generally undesirable for aspects of film quality, electrical insulation and
+dielectric performance. However, if we view these pores as natural
+nano-patterns embedded in a dielectric matrix then that opens up new vistas for
+exploration. The nano-pattern platform can be used to tailor electrical,
+optical, magnetic and mechanical properties of the carrier film. In this
+article we report the tunable electrical properties of thermal SiO2 thin-film
+achieved through utilization of the metal-nanopore network where the pores are
+filled with metallic Titanium (Ti). Without any intentional chemical doping, we
+have shown that the electrical resistivity of the oxide film can be controlled
+through physical filling up of the intrinsic oxide nanopores with Ti. The
+electrical resistance of the composite film remains constant even after
+complete removal of the metal from the film surface except the pores. Careful
+morphological, electrical and structural analyses are carried out to establish
+that the presence of Ti in the nanopores play a crucial role in the observed
+conductive nature of the nanoporous film.",1709.03259v1
+2017-11-07,Epitaxial stabilization of pulsed laser deposited Sr$_{n+1}$Ir$_n$O$_{3n+1}$ thin films: entangled effect of growth dynamics and strain,"The subtle balance of electronic correlations, crystal field splitting and
+spin--orbit coupling in layered Ir$^{4+}$ oxides can give rise to novel
+electronic and magnetic phases. Experimental progress in this field relies on
+the synthesis of epitaxial films of these oxides. However, the growth of
+layered iridates with excellent structural quality is a great experimental
+challenge. Here we selectively grow high quality single--phase films of
+Sr$_2$IrO$_4$, Sr$_3$Ir$_2$O$_7$, and SrIrO$_3$ on various substrates from a
+single Sr$_3$Ir$_2$O$_7$ target by tuning background oxygen pressure and
+epitaxial strain. We demonstrate a complex interplay between growth dynamics
+and strain during thin film deposition. Such interplay leads to the
+stabilization of different phases in films grown on different substrates under
+identical growth conditions, which cannot be explained by a simple kinetic
+model. We further investigate the thermoelectric properties of the three phases
+and propose that weak localization is responsible for the low temperature
+activated resistivity observed in SrIrO$_3$ under compressive strain.",1711.02767v3
+2018-12-21,Influence of spin-orbit and spin-Hall effects on the spin Seebeck current beyond linear response,"We study the spin transport theoretically in heterostructures consisting of a
+ferromagnetic metallic thin film sandwiched between heavy-metal and oxide
+layers. The spin current in the heavy metal layer is generated via the spin
+Hall effect, while the oxide layer induces at the interface with the
+ferromagnetic layer a spin-orbital coupling of the Rashba type. Impact of the
+spin Hall effect and Rashba spin-orbit coupling on the spin Seebeck current is
+explored with a particular emphasis on nonlinear effects. Technically, we
+employ the Fokker-Planck approach and contrast the analytical expressions with
+full numerical micromagnetic simulations. We show that when an external
+magnetic field is aligned parallel (antiparallel) to the Rashba field, the
+spin-orbit coupling enhances (reduces) the spin pumping current. In turn, the
+spin Hall effect and the Dzyaloshinskii-Moriya interaction are shown to
+increase the spin pumping current.",1812.09270v1
+2019-01-28,X-ray scattering characterization of iron oxide nanoparticles Langmuir film on water surface and on a solid substrate,"In the present study we compare a structure of a Langmuir film assembled from
+magnetic iron oxide nanoparticles on water surface and a structure of the same
+film after its transfer to a solid substrate by the Langmuir-Schaefer method.
+In contrast to most of related studies, where different techniques are used to
+characterize the films before and after the deposition, we use the same
+combination of X-ray reflectometry and Grazing Incidence Small-Angle X-ray
+scattering. In both cases -- on a liquid and on a solid substrate -- the film
+was identified as a well-ordered monolayer of the nanoparticles laterally
+organized in a two-dimensional hexagonal lattice. However parameters of the
+lattice were found to be slightly different depending on the type of the
+substrate. It is also demonstrated that Langmuir-Schaefer technique is the
+right way for deposition of such kind of the particles on a solid substrate.",1901.09636v1
+2019-02-09,Revealing the Hidden Heavy Fermi Liquid in CaRuO3,"The perovskite ruthenate has attracted considerable interest due to reports
+of possible non-Fermi-liquid behavior and its proximity to a magnetic quantum
+critical point, yet its ground state and electronic structure remain enigmatic.
+Here we report the first measurements of the Fermi surface and quasiparticle
+dispersion in CaRuO3 through a combination of oxide molecular beam epitaxy and
+in situ angle-resolved photoemission spectroscopy. Our results reveal a complex
+and anisotropic Fermi surface consisting of small electron pockets and straight
+segments, consistent with the bulk orthorhombic crystal structure with large
+octahedral rotations. We observe a strongly band-dependent mass
+renormalization, with prominent heavy quasiparticle bands which lie close to
+the Fermi energy and exhibit strong temperature dependence. These results are
+consistent with a heavy Fermi liquid with a complex Fermiology and small
+hybridization gaps near the Fermi energy. Our results provide a unified
+framework for explaining previous experimental results on CaRuO3, such as its
+unusual optical conductivity, and demonstrate the importance of octahedral
+rotations in determining the quasiparticle band structure, and electron
+correlations in complex transition metal oxides.",1902.03359v1
+2019-03-01,Engineering Transport in Manganites by Tuning Local Non-Stoichiometry in Grain Boundaries,"Interface-dominated materials such as nanocrystalline thin films have emerged
+as an enthralling class of materials able to engineer functional properties of
+transition metal oxides widely used in energy and information technologies. In
+particular, it has been proved that strain-induced defects in grain boundaries
+of manganites deeply impact their functional properties by boosting their
+oxygen mass transport while abating their electronic and magnetic order. In
+this work, the origin of these dramatic changes is correlated for the first
+time with strong modifications of the anionic and cationic composition in the
+vicinity of strained grain boundary regions. We are also able to alter the
+grain boundary composition by tuning the overall cationic content in the films,
+which represents a new and powerful tool, beyond the classical space charge
+layer effect, for engineering electronic and mass transport properties of metal
+oxide thin films useful for a collection of relevant solid state devices.",1903.00225v1
+2019-03-12,Magnetism tailored by mechanical strain engineering in PrVO$_3$ thin films,"Transition-metal oxides with an ABO$_3$ perovskite structure exhibit strongly
+entangled structural and electronic degrees of freedom and thus, one expects to
+unveil exotic phases and properties by acting on the lattice through various
+external stimuli. Using the Jahn-Teller active praseodymium vanadate
+Pr$^{3+}$V$^{3+}$O$_3$ compound as a model system, we show that PrVO$_3$ N\'eel
+temperature T$_N$ can be raised by 40 K with respect to the bulk when grown as
+thin films. Using advanced experimental techniques, this enhancement is
+unambiguously ascribed to a tetragonality resulting from the epitaxial
+compressive strain experienced by the films. First-principles simulations not
+only confirm experimental results, but they also reveal that the strain
+promotes an unprecedented orbital-ordering of the V$^{3+}$ d electrons,
+strongly favouring antiferromagnetic interactions. These results show that an
+accurate control of structural aspects is the key for unveiling unexpected
+phases in oxides.",1903.04791v1
+2020-08-24,Dependence of the Nonlinear-Optical Response of Materials on their Linear $ε$ and $μ$,"We investigate, theoretically and numerically, the dependence of a material's
+nonlinear-optical response on the linear relative electric permittivity
+$\epsilon$ and magnetic permeability $\mu$. The conversion efficiency of
+low-order harmonic-generation processes, as well as the increase rate of
+Kerr-effect nonlinear phase shift and nonlinear losses from two-photon
+absorption (TPA), are seen to increase with decreasing $\epsilon$ and/or
+increasing $\mu$. We also discuss the rationale and physical insights behind
+this nonlinear response, particularly its enhancement in $\epsilon$-near-zero
+(ENZ) media. This behavior is consistent with the experimental observation of
+intriguingly high effective nonlinear refractive index in degenerate
+semiconductors such as indium tin oxide [\textit{Alam et al., Science 352
+(795), 2016}] (where the nonlinearity is attributed to a modification of the
+energy distribution of conduction-band electrons due to laser-induced electron
+heating) and aluminum zinc oxide [\textit{Caspani et al., Phys. Rev. Lett. 116
+(233901), 2016}] at frequencies with vanishing real part of the linear
+permittivity. Such strong nonlinear response can pave the way for a new
+paradigm in nonlinear optics with much higher conversion efficiencies and
+therefore better miniaturization capabilities and power requirements for
+next-generation integrated nanophotonics.",2008.10512v1
+2020-08-27,Particle-hole asymmetric lifetimes promoted by spin and orbital fluctuations in SrVO$_3$ monolayers,"The two-dimensional nature of engineered transition-metal ultra-thin oxide
+films offers a large playground of yet to be fully understood physics. Here, we
+study pristine SrVO$_3$ monolayers that have recently been predicted to display
+a variety of magnetic and orbital orders. Above all ordering temperatures, we
+find that the associated non-local fluctuations lead to a momentum
+differentiation in the self-energy, particularly in the scattering rate. In the
+one-band 2D Hubbard model, momentum-selectivity on the Fermi surface
+(""$k=k_F$"") is known to lead to pseudogap physics. Here instead, in the
+multi-orbital case, we evidence a differentiation between momenta on the
+occupied (""$k<k_F$"") and the unoccupied side (""$k>k_F$"") of the Fermi surface.
+Our work, based on the dynamical vertex approximation, complements the
+understanding of spectral signatures of non-local fluctuations, calls to
+(re)examine other ultra-thin oxide films and interfaces with methods beyond
+dynamical mean-field theory, and may point to correlation-enhanced
+thermoelectric effects.",2008.12227v2
+2021-02-01,"Strong magneto-optical effects in ACr2O4 A=Fe, Co spinel oxides generated by tetrahedrally coordinated transition metal ions","Magneto-optical effects have been investigated over the infrared{visible
+spectral range in ACr2O4 (A = Fe, Co) spinel oxides with non-collinear spin
+orders in their ground states. We found large magneto-optical Kerr rotation and
+ellipticity at the on-site d-d transitions of the A2+ ions located within the
+charge gap. The magneto-optical Kerr rotation of 12 deg observed in CoCr2O4 is
+unprecedentedly large among magnetic semiconductors and points towards the
+uniqueness of tetrahedrally coordinated Co2+ ions in generating a strong
+magneto-optical response. Criteria of strong magneto-optical effects emerging
+at on-site d-d transitions of transition metal ions are discussed.",2102.00956v1
+2021-03-03,Near-Room Temperature Ferromagnetic Insulating State in Highly Distorted LaCoO2.5 with CoO5 Square Pyramids,"Dedicated control of oxygen vacancies is an important route to
+functionalizing complex oxide films. It is well-known that tensile strain
+significantly lowers the oxygen vacancy formation energy, whereas compressive
+strain plays a minor role. Thus, atomically reconstruction by extracting oxygen
+from a compressive-strained film is challenging. Here we report an unexpected
+LaCoO2.5 phase with a zigzag-like oxygen vacancy ordering through annealing a
+compressive-strained LaCoO3 in vacuum. The synergetic tilt and distortion of
+CoO5 square pyramids with large La and Co shifts are quantified using scanning
+transmission electron microscopy. The large in-plane expansion of CoO5 square
+pyramids weaken the crystal-field splitting and facilitated the ordered
+high-spin state of Co2+, which produces an insulating ferromagnetic state with
+a Curie temperature of ~284 K and a saturation magnetization of ~0.25
+{\mu}B/Co. These results demonstrate that extracting targeted oxygen from a
+compressive-strained oxide provides an opportunity for creating unexpected
+crystal structures and novel functionalities.",2103.02100v1
+2021-04-15,Magnetotransport of Functional Oxide Heterostructures Affected by Spin-Orbit Coupling: A Tale of Two-Dimensional Systems,"Oxide heterostructures allow for detailed studies of 2D electronic transport
+phenomena. Herein, different facets of magnetotransport in selected
+spin-orbit-coupled systems are analyzed and characterized by their single-band
+and multiband behavior, respectively. Experimentally, temperature- and magnetic
+field-dependent measurements in the single-band system BaPbO$_3$/SrTiO$_3$
+reveal strong interplay of weak antilocalization (WAL) and electron-electron
+interaction (EEI). Within a scheme which treats both, WAL and EEI, on an equal
+footing a strong contribution of EEI at low temperatures is found which
+suggests the emergence of a strongly correlated ground state. Furthermore, now
+considering multiband effects as they appear, e.g., in the model system
+LaAlO$_3$/SrTiO$_3$, theoretical investigations predict a huge impact of
+filling on the topological Hall effect in systems with intermingled bands.
+Already weak band coupling produces striking deviations from the well-known
+Hall conductivity that are explainable in a fully quantum mechanical treatment
+which builds upon the hybridization of intersecting Hofstadter bands.",2104.07270v2
+2021-04-28,Visualizing quantum phenomena at complex oxide interfaces: an atomic view from scanning transmission electron microscopy,"Complex oxide interfaces have been one of the central focuses in condensed
+matter physics and material science. Over the past decade, aberration corrected
+scanning transmission electron microscopy and spectroscopy has proven to be
+invaluable to visualize and understand the emerging quantum phenomena at an
+interface. In this paper, we briefly review some recent progress in the
+utilization of electron microscopy to probe interfaces. Specifically, we
+discuss several important challenges for electron microscopy to advance our
+understanding on interface phenomena, from the perspective of variable
+temperature, magnetism, electron energy loss spectroscopy analysis, electronic
+symmetry, and defects probing.",2104.13587v1
+2021-04-28,From Slater to Mott physics: epitaxial engineering of electronic correlations in oxide interfaces,"Using spin-assisted ab-initio random structure searches, we explore an
+exhaustive quantum phase diagram of archetypal interfaced Mott insulators, i.e.
+lanthanum-iron and lanthanum-titanium oxides. In particular, we report that the
+charge transfer induced by the interfacial electronic reconstruction stabilises
+a high spin ferrous Fe2+ state. We provide a pathway to control the strength of
+correlation in this electronic state by tuning the epitaxial strain, yielding a
+manifold of quantum electronic phases, i.e. Mott-Hubbard, charge transfer and
+Slater insulating states. Furthermore we report that the electronic
+correlations are closely related to the structural oxygen octahedral rotations,
+whose control is able to stabilise the low spin state of Fe2+ at low pressure
+previously observed only under the extreme high pressure conditions in the
+Earth's lower mantle. Thus we provide avenues for magnetic switching via THz
+radiations which have crucial implications for next generation of spintronics
+technologies.",2104.13723v1
+2021-06-25,"Interplay between polarization, strain and defect-pairs in Fe-doped SrMnO$_{3-δ}$","Defect chemistry, strain, and structural, magnetic and electronic degrees of
+freedom constitute a rich space for the design of functional properties in
+transition metal oxides. Here, we show that it is possible to engineer polarity
+and ferroelectricity in non-polar perovskite oxides via polar defect pairs
+formed by anion vacancies coupled to substitutional cations. We use a
+self-consistent site-dependent DFT+$U$ approach that accounts for local
+structural and chemical changes upon defect creation and which is crucial to
+reconcile predictions with the available experimental data. Our results for
+Fe-doped oxygen-deficient SrMnO$_3$ show that substitutional Fe and oxygen
+vacancies can promote polarity due to an off-center displacement of the defect
+charge resulting in a net electric dipole moment, which polarizes the lattice
+in the defect neighborhood. The formation of these defects and the resulting
+polarization can be tuned by epitaxial strain, resulting in enhanced
+polarization also for strain values lower than the ones necessary to induce a
+polar phase transition in undoped SrMnO$_3$. For high enough defect
+concentrations, these defect dipoles couple in a parallel fashion, thus
+enabling defect- and strain-based engineering of ferroelectricity in SrMnO$_3$.",2106.13854v1
+2021-06-28,Optical and excitonic properties of transition metal oxide perovskites by the Bethe-Salpeter equation,"We present a systematic investigation of the role and importance of excitonic
+effects on the optical properties of transitions metal oxide perovskites. A
+representative set of fourteen compounds has been selected, including 3$d$
+(SrTiO$_3$, LaScO$_3$, LaTiO$_3$, LaVO$_3$, LaCrO$_3$, LaMnO$_3$, LaFeO$_3$ and
+SrMnO$_3$), 4$d$ (SrZrO$_3$, SrTcO$_3$ and Ca$_2$RuO$_4$) and 5$d$ (SrHfO$_3$,
+KTaO$_3$ and NaOsO$_3$) perovskites, covering a band gap ranging from 0.1 eV to
+6.1 eV and exhibiting different electronic, structural and magnetic properties.
+Optical conductivities and optical transitions including electron-hole
+interactions are calculated through the solution of the Bethe-Salpeter equation
+(BSE) with quasi-particle energies evaluated by single-shot $G_0W_0$
+approximation. The exciton binding energies are computed by means of a
+model-BSE (mBSE), carefully benchmarked against the full BSE method, in order
+to obtain well-converged results in terms of k-point sampling. The predicted
+results are compared with available measured data, with an overall satisfactory
+agreement between theory and experiment.",2106.14632v1
+2021-08-01,Cobalt in strontium titanate as a new off-center magnetic impurity,"The local structure and oxidation state of the cobalt impurity in SrTiO$_3$
+is studied by X-ray absorption fine structure (XAFS) spectroscopy. The
+synthesis conditions, under which cobalt predominantly (up to 76%) substitutes
+the atoms at the $A$ site of the perovskite structure, is found for
+SrTiO$_3$(Co) samples. By varying the synthesis conditions, it is possible to
+appreciably change the ratio between the concentrations of cobalt atoms
+incorporated into the $A$ and $B$ sites. It is established that the oxidation
+state of cobalt is +2 at the $A$ site and +3 at the $B$ site. It is revealed
+that the Co impurity at the $A$ site is off-center, and its displacement from
+the lattice site is $\sim$1.0 {\AA}. First-principles calculations show that an
+isolated Co$^{3+}$ ion at the $B$ site is diamagnetic, whereas the Co$^{2+}$
+ion at the $A$ site is in a high-spin state ($S = 3/2$).",2108.00481v1
+2021-09-22,"Design, Fabrication, Characterization and Reliability Study of CMOS-MEMS Lorentz-Force Magnetometers","This article presents several design techniques to fabricate
+micro-electro-mechanical systems (MEMS) using standard complementary
+metal-oxide semiconductor (CMOS) processes. They were applied to fabricate high
+yield CMOS-MEMS shielded Lorentz-force magnetometers (LFM). The multilayered
+metals and oxides of the back-end-of-line (BEOL), normally used for electronic
+routing, comprise the structural part of the MEMS. The most important
+fabrication challenges, modeling approaches and design solutions are discussed.
+Equations that predict the Q factor, sensitivity, Brownian noise and resonant
+frequency as a function of temperature, gas pressure and design parameters are
+presented and validated in characterization tests. A number of the fabricated
+magnetometers were packaged into Quad Flat No-leads (QFN) packages. We show
+this process can achieve yields above 95 % when the proper design techniques
+are adopted. Despite CMOS not being a process for MEMS manufacturing, estimated
+performance (sensitivity and noise level) is similar or superior to current
+commercial magnetometers and others built with MEMS processes. Additionally,
+typical offsets present in Lorentz-force magnetometers were prevented with a
+shielding electrode, whose efficiency is quantified. Finally, several
+reliability test results are presented, which demonstrate the robustness
+against high temperatures, magnetic fields and acceleration shocks.",2109.10980v1
+2022-02-03,A Novel Single-Mode Microwave Assisted Synthesis of Metal Oxide as Visible-light Photocatalyst,"Visible-light photocatalyst titanium dioxide (TiO2) was successfully prepared
+via a novel and facile single-mode microwave assisted synthesis process. In
+this one-step synthesis, Ti as target material selectively oxides in magnetic
+field throughout rapid heating, whose process requires less energy consumption
+and short time. In obtained TiO2, self-doping of Ti3+ was confirmed, which
+makes TiO2 performed sufficient light absorption in visible region with
+wavelength above 400 nm. Such Ti3+ self-doped TiO2 exhibits much narrower
+optical bandgap (2.14 eV) to compare with stoichiometric TiO2 (3.0-3.2 eV). The
+synthesized TiO2 also shows superior photocatalytic activity to commercially
+available TiO2 towards the degradation of Rhodamine B under visible light
+irradiation.",2202.01360v1
+2022-02-04,Engineering multifunctionality at oxide interfaces by multimode coupling,"We employed first-principles density functional theory calculations guided by
+group-theoretical analysis and demonstrated the control of
+insulator-metal-insulator transition, polarization and two sublattice
+magnetization in (LaFeO$_3$)$_1$/(CaFeO$_3$)$_1$ superlattice via. multi
+structural mode coupling i.e., 'multimode coupling'. We have discovered a polar
+A-type charge disproportionation mode, Q$_{ACD}$ (analogous to the A-type
+antiferromagnetic ordering), and found that it couples with the trilinear
+coupling, $Q_{Tri}$ mode (common in $Pnma$ perovskite oxides and involves three
+structural modes), and lowers the symmetry further. By tuning the strength of
+the coupling between the participating modes, the polar metallic phase, polar
+zero bandgap semiconducting, and polar insulating phases can be obtained. Here,
+$Q_{Tri}$ switches the polarization direction, whereas, Q$_{ACD}$ can trigger
+insulator-metal-insulator transition along with the polarization switching. The
+mechanism is true for any transition metal superlattices constituted with
+$Pnma$ building blocks and with partially filled $e_g$ or $t_{2g}$ electron(s)
+at the transition metal sites.",2202.02027v1
+2022-09-04,Spin-Polarisation measurement using NbN-Insulator-Ferromagnet Tunnel Junction with oxidized barrier,"We report a two-step process for the fabrication of
+superconductor-insulator-normal metal tunnel junctions using NbN as the
+superconducting electrode and its surface oxide as the insulating tunnel
+barrier, and investigate its efficacy in measuring spin-polarisation of
+ferromagnets using the Meservey-Tedrow technique. We observe that for NbN film
+thickness below 10 nm, under the application of parallel magnetic field, the
+superconducting density of states show clear ""Zeeman"" splitting into spin-up
+and spin-down sub-bands. Tunnelling measurements on devices where ferromagnetic
+Co is used as the normal electrode shows that these devices can be used to
+reliably measure spin polarisation of a ferromagnet at temperatures up to 1.6
+K. The simplicity of our fabrication process, and the ability to perform
+spin-polarisation measurements at 4He temperatures makes NbN a very attractive
+candidate for spin polarisation measurements.",2209.01626v1
+2022-10-18,Strain sensitive flexible magnetoelectric ceramic nanocomposites,"Advanced flexible electronics and soft robotics require the development and
+implementation of flexible functional materials. Magnetoelectric (ME) oxide
+materials can convert magnetic input into electric output and vice versa,
+making them excellent candidates for advanced sensing, actuating, data storage,
+and communication. However, their application has been limited to rigid devices
+due to their brittle nature. Here, we report flexible ME oxide composite
+(BaTiO3/CoFe2O4) thin film nanostructures that can be transferred onto a
+stretchable substrate such as polydimethylsiloxane (PDMS). In contrast to rigid
+bulk counterparts, these ceramic nanostructures display a flexible behavior and
+exhibit reversibly tunable ME coupling via mechanical stretching. We believe
+our study can open up new avenues for integrating ceramic ME composites into
+flexible electronics and soft robotic devices.",2210.09679v1
+2022-10-26,Oxygen vacancies at the origin of pinned moments in oxide interfaces: the example of tetragonal CuO/SrTiO$_3$,"Obtaining an accurate theoretical description of the emergent phenomena in
+oxide heterostructures is a major challenge. Recently, intriguing paramagnetic
+spin and pinned orbital moments have been discovered by x-ray magnetic circular
+dichro\""ism measurements at the Cu $L_{2,3}$-edge of a tetragonal CuO/SrTiO$_3$
+heterostructure. Using first principles calculations, we propose a scenario
+that explains both types of moments, based on the formation of oxygen vacancies
+in the TiO$_2$ interface layer. We show the emergence of a paramagnetic 2D
+electron gas hosted in the interface CuO layer. It is invisible at the Ti
+$L_{2,3}$-edge since the valence of the Ti atoms remains unchanged. Strong
+structural distortions breaking both the local and global fourfold rotation
+$C_4$ symmetries at the interface lead to the in-plane pinning of the Cu
+orbital moment close to the vacancy. Our results, and in particular the pinning
+of the orbital moment, may have implications for other systems, especially
+monoxide/dioxide interfaces with similar metal-oxygen bond length and weak
+spin-orbit coupling.",2210.15084v1
+2023-01-04,Atomic and Electronic Structures of Correlated SrRuO3/SrTiO3 Superlattices,"Atomic-scale precision epitaxy of perovskite oxide superlattices provides
+unique opportunities for controlling the correlated electronic structures,
+activating effective control knobs for intriguing functionalities including
+electromagnetic, thermoelectric, and electrocatalytic behaviors. In this study,
+we investigated the close interplay between the atomic and electronic
+structures of correlated superlattices synthesized by atomic-scale precision
+epitaxy. In particular, we employ superlattices composed of correlated magnetic
+SrRuO3 (SRO) and quantum paraelectric SrTiO3 (STO) layers. In those
+superlattices, RuO6 octahedral distortion is systematically controlled from 167
+to 175 degrees depending on the thickness of the STO layers, also affecting the
+TiO6 octahedral distortion within the STO layer. Customized octahedral
+distortion within SRO/STO superlattices in turn modifies the electronic
+structures of both the Ti and Ru compounds, observed by X-ray absorption
+spectroscopy. Our results identify the close correlation between atomic lattice
+and electronic structures enabled by the facile controllability of atomic-scale
+epitaxy, which would be useful for designing future correlated oxide devices.",2301.01406v1
+2023-04-24,Electronic Correlation-driven Exotic Quantum Phase Transitions in Infinite-layer Manganese Oxide,"Despite the intensive interest in copper- and nickel-based superconductivity
+in infinite-layer structures, the physical properties of many other
+infinite-layer transition-metal oxides remain largely unknown. Here we unveil,
+by the first-principles calculations, the electronic correlation-driven quantum
+phase transitions in infinite-layer SrMnO2, where spin and charge orders are
+strongly interwoven. At weak electronic correlation region, SrMnO2 is a
+ferromagnetic metal with anisotropic spin transportation, as a promising spin
+valve under room-temperature. At middle electronic correlation region, a
+structural transition accompanied by charge/bond disproportion occurs as a
+consequence of Fermi surface nesting, resulting in a ferromagnetic insulator
+with reduced Curie temperature. At strong electronic correlation region,
+another structural transition occurs that drives the system into degenerately
+antiferromagnetic insulators with tunable magnetic order by piezoelectricity, a
+new type of multiferroics. Therefore, infinite-layer SrMnO2 is possibly a
+unique system on the quantum critical point, where electronic correlation can
+induce noticeable Fermi surface evolutions and small perturbations can realize
+remarkable quantum phase transitions.",2304.11777v1
+2023-05-20,Magnetostriction-Driven Muon Localization in an Antiferromagnetic Oxide,"Magnetostriction drives a rhombohedral distortion in the cubic rock salt
+antiferromagnet MnO at the N\'eel temperature $T_{N}=118$ K. As an unexpected
+consequence we show that this distortion acts to localize the site of an
+implanted muon due to the accompanying redistribution of electron density. This
+lifts the degeneracy between equivalent sites, resulting in a single observed
+muon precession frequency. Above $T_{N}$, the muon instead becomes delocalized
+around a network of equivalent sites. Our first-principles simulations based on
+Hubbard-corrected density-functional theory and molecular dynamics are
+consistent with our experimental data and help to resolve a long-standing
+puzzle regarding muon data on MnO, as well as having wider applicability to
+other magnetic oxides.",2305.12237v3
+2023-05-29,Zeeman dependence of the quasiparticle scattering rate and ARPES in copper oxides and related materials,"Within a strongly interacting Fermi liquid framework, we calculate the
+effects of the Zeeman energy $\omega_H$ for a finite magnetic field, in a
+metallic system with a van Hove peak in the density of states, located close to
+and below the Fermi surface. We find that the chemical potential increases with
+the square of $\omega_H$. We obtain a characteristic quasiparticle scattering
+rate linear in the maximum of $\omega_H$ and temperature, both in the normal
+and the d-wave superconducting state. We predict that ARPES experiments in
+copper oxides, and related compounds, should be able to elucidate this behavior
+of the scattering rate, and in particular, the difference between spin up and
+down electrons.",2305.18083v2
+2023-08-16,Dynamic motion of polar skyrmions in oxide heterostructures,"Polar skyrmions have been widely investigated in oxide heterostructure
+recently, due to their exotic properties and intriguing physical insights.
+Meanwhile, so far, the external field-driven motion of the polar skyrmion, akin
+to the magnetic counterpart, has yet to be discovered. Here, using phase-field
+simulations, we demonstrate the dynamic motion of the polar skyrmions with
+integrated external thermal, electrical, and mechanical stimuli. The external
+heating reduces the spontaneous polarization hence the skyrmion motion barrier,
+while the skyrmions shrink under the electric field, which could weaken the
+lattice pinning and interactions between the skyrmions. The mechanical force
+transforms the skyrmions into c-domain in the vicinity of the indenter center
+under the electric field, providing the space and driving force needed for the
+skyrmions to move. This study confirmed that the skyrmions are quasi-particles
+that can move collectively, while also providing concrete guidance for the
+further design of polar skyrmion-based electronic devices.",2308.08219v1
+2023-10-09,Pressure-Driven Transitions in La2CoTiO6: Antiferromagnetic Insulator to Nonmagnetic Metal via Antiferromagnetic Metal in a Double Perovskite Oxide,"La$_2$CoTiO$6$ (LCTO), a double perovskite oxide, transitions from an
+antiferromagnetic insulator (AFM-I) to an antiferromagnetic metal (AFM-M) and
+eventually to a nonmagnetic metal (NM-M) under external hydrostatic pressure.
+This pressure-driven sequence is accompanied by a shift in spin states, with a
+remarkable spin-state transition from high-spin (HS) to low-spin (LS) at $\sim$
+42 GPa. Monoclinic distortion induced by pressure plays a key role in this
+transition. Even under ambient conditions, the LS state persists in a highly
+symmetric theoretical structure, highlighting the role of distortion in
+facilitating the HS to LS transition. In the LS state, LCTO becomes metallic,
+even with a strong local correlation (Hubbard $U$) on Co. This transition is
+elucidated through an energy level diagram, revealing a substantial
+modification in the crystal field splitting between Co-$t{2g}$ and -$e_g$
+levels due to strong Co-$d$ and O-$p$ orbital hybridization. Beyond 130 GPa,
+the system enters the NM-M phase, completely quenching the magnetic moment on
+Co.",2310.05523v1
+2022-06-17,The Open Catalyst 2022 (OC22) Dataset and Challenges for Oxide Electrocatalysts,"The development of machine learning models for electrocatalysts requires a
+broad set of training data to enable their use across a wide variety of
+materials. One class of materials that currently lacks sufficient training data
+is oxides, which are critical for the development of OER catalysts. To address
+this, we developed the OC22 dataset, consisting of 62,331 DFT relaxations
+(~9,854,504 single point calculations) across a range of oxide materials,
+coverages, and adsorbates. We define generalized total energy tasks that enable
+property prediction beyond adsorption energies; we test baseline performance of
+several graph neural networks; and we provide pre-defined dataset splits to
+establish clear benchmarks for future efforts. In the most general task,
+GemNet-OC sees a ~36% improvement in energy predictions when combining the
+chemically dissimilar OC20 and OC22 datasets via fine-tuning. Similarly, we
+achieved a ~19% improvement in total energy predictions on OC20 and a ~9%
+improvement in force predictions in OC22 when using joint training. We
+demonstrate the practical utility of a top performing model by capturing
+literature adsorption energies and important OER scaling relationships. We
+expect OC22 to provide an important benchmark for models seeking to incorporate
+intricate long-range electrostatic and magnetic interactions in oxide surfaces.
+Dataset and baseline models are open sourced, and a public leaderboard is
+available to encourage continued community developments on the total energy
+tasks and data.",2206.08917v3
+2020-02-13,"Multipolar magnetism in d-orbital systems: Crystal field levels, octupolar order, and orbital loop currents","Quantum magnets with spin $J=2$, which arise in spin-orbit coupled Mott
+insulators, can potentially display multipolar orders. We carry out an exact
+diagonalization study of a simple octahedral crystal field Hamiltonian for two
+electrons, incorporating spin-orbit coupling (SOC) and interactions, finding
+that either explicitly including the $e_g$ orbitals, or going beyond the
+rotationally invariant Coulomb interaction within the $t_{2g}$ sector, causes a
+degeneracy breaking of the $J\!=\!2$ level degeneracy. This can lead to a
+low-lying non-Kramers doublet carrying quadrupolar and octupolar moments and an
+excited triplet which supports magnetic dipole moments, bolstering our previous
+phenomenological proposal for the stabilization of ferro-octupolar order in
+heavy transition metal oxides. We show that the spontaneous time-reversal
+symmetry breaking due to ferro-octupolar ordering within the non-Kramers
+doublet leads to electronic orbital loop currents. The resulting internal
+magnetic fields can potentially explain the small fields inferred from
+muon-spin relaxation ($\mu$SR) experiments on cubic $5d^2$ osmate double
+perovskites Ba$_2$ZnOsO$_6$, Ba$_2$CaOsO$_6$, and Ba$_2$MgOsO$_6$, which were
+previously attributed to weak dipolar magnetism. We make further predictions
+for oxygen NMR experiments on these materials. We also study the reversed level
+scheme, where the $J\!=\!2$ multiplet splits into a low-lying magnetic triplet
+and excited non-Kramers doublet, presenting single-ion results for the magnetic
+susceptibility in this case, and pointing out its possible relevance for the
+rhenate Ba$_2$YReO$_6$. Our work highlights the intimate connection between the
+physics of heavy transition metal oxides and that of $f$-electron based heavy
+fermion compounds.",2002.05737v2
+2022-02-16,"Spin Seebeck effect in iron oxide thin films: Effects of phase transition, phase coexistence, and surface magnetism","Understanding impacts of phase transition, phase coexistence, and surface
+magnetism on the longitudinal spin Seebeck effect (LSSE) in a magnetic system
+is essential to manipulate the spin to charge current conversion efficiency for
+spincaloritronic applications. We aim to elucidate these effects by performing
+a comprehensive study of the temperature dependence of LSSE in biphase iron
+oxide (BPIO = alpha-Fe2O3 + Fe3O4) thin films grown on Si (100) and Al2O3 (111)
+substrates. A combination of temperature-dependent anomalous Nernst effect
+(ANE) and electrical resistivity measurements show that the contribution of ANE
+from the BPIO layer is negligible compared to the intrinsic LSSE in the
+Si/BPIO/Pt heterostructure even at room temperature. Below the Verwey
+transition of the Fe3O4 phase, the total signal across BPIO/Pt is dominated by
+the LSSE. Noticeable changes in the intrinsic LSSE signal for both Si/BPIO/Pt
+and Al2O3/BPIO/Pt heterostructures around the Verwey transition of the Fe3O4
+phase and the antiferromagnetic (AFM) Morin transition of the alpha-Fe2O3 phase
+are observed. The LSSE signal for Si/BPIO/Pt is found to be almost two times
+greater than that for Al2O3/BPIO/Pt, an opposite trend is observed for the
+saturation magnetization though. Magnetic force microscopy reveals the higher
+density of surface magnetic moments of the Si/BPIO film compared to the
+Al2O3/BPIO film, which underscores a dominant role of interfacial magnetism on
+the LSSE signal and thereby explains the larger LSSE for Si/BPIO/Pt.",2202.07910v1
+2018-12-11,First-Principles Study of Localised and Delocalised Electronic States in Crystallographic Shear Phases of Niobium Oxide,"Crystallographic shear phases of niobium oxide form an interesting family of
+compounds that have received attention both for their unusual electronic and
+magnetic properties, as well as their performance as intercalation electrode
+materials for lithium-ion batteries. Here, we present a first-principles
+density-functional theory study of the electronic structure and magnetism of
+H-Nb$_2$O$_5$, Nb$_{25}$O$_{62}$, Nb$_{47}$O$_{116}$, Nb$_{22}$O$_{54}$, and
+Nb$_{12}$O$_{29}$. These compounds feature blocks of niobium-oxygen octahedra
+as structural units, and we show that this block structure leads to a
+coexistence of flat and dispersive energy bands, corresponding to localised and
+delocalised electronic states. Electrons localise in orbitals spanning multiple
+niobium sites in the plane of the blocks. Localised and delocalised electronic
+states are both effectively one-dimensional and are partitioned between
+different types of niobium sites. Flat bands associated with localised
+electrons are present even at the GGA level, but a correct description of the
+localisation requires the use of GGA+U or hybrid functionals. We discuss the
+experimentally observed electrical and magnetic properties of niobium suboxides
+in light of our results, and argue that their behaviour is similar to that of
+$n$-doped semiconductors, but with a limited capacity for localised electrons.
+When a threshold of one electron per block is exceeded, metallic electrons are
+added to existing localised electrons. We propose that this behaviour of shear
+phases is general for any type of $n$-doping, and should transfer to doping by
+alkali metal (lithium) ions during operation of niobium oxide-based battery
+electrodes. Future directions for theory and experiment on mixed-metal shear
+phases are suggested.",1812.04632v2
+2021-11-16,DFT+U+J with linear response parameters predicts non-magnetic oxide band gaps with hybrid-functional accuracy,"First-principles Hubbard-corrected approximate density-functional theory
+(DFT+U) is a low-cost, potentially high throughput method of simulating
+materials, but it has been hampered by empiricism and inconsistent band-gap
+correction in transition-metal oxides. DFT+U property prediction of
+non-magnetic systems such as d0 and d10 transition-metal oxides is typically
+faced with excessively large calculated Hubbard U values, and with difficulty
+in obtaining acceptable band-gaps and lattice volumes. Meanwhile, Hund's
+exchange coupling J is an important but often neglected component of DFT+U, and
+the J parameter has proven challenging to directly calculate by means of linear
+response. In this work, we provide a revised formula for computing Hund's J
+using established self-consistent field DFT+U codes. For non-magnetic systems,
+we introduce a non-approximate technique for calculating U and J simultaneously
+in such codes, at no additional cost. Using unmodified Quantum ESPRESSO, we
+assess the resulting values using two different DFT+U functionals incorporating
+J, namely the widely used DFT+(U-J) and the readily available DFT+U+J. We
+assess a test set comprising TiO2, ZrO2, HfO2, Cu2O and ZnO, and apply the
+corrections both to metal and oxygen centered pseudoatomic subspaces. Starting
+from the PBE functional, we find that DFT+(U-J) is significantly out-performed
+in band-gap accuracy by DFT+U+J, the RMS band-gap error of which matches that
+of the hybrid functional HSE06. ZnO, a long-standing challenge case for DFT+U,
+is addressed by means of Zn 4s instead of Zn 3d correction, in which case the
+first-principles DFT+U+J band-gap error is half of that reported for HSE06.",2111.08487v1
+2022-07-28,Symmetry protected 1D chains in mixed-valence iron oxides,"During the last decade of high-pressure research a whole new series of iron
+oxides was discovered, like Fe$_4$O$_5$, Fe$_5$O$_6$, Fe$_7$O$_9$ etc.,
+featuring closely related structures with arrays of one-dimensional (1D) chains
+of trigonal prisms embedded between slabs of octahedra. Here, we develop a
+unified approach to the series based on a specific crystallographic generation
+mechanism which predicts the structures of these oxides and naturally
+classifies them in terms of the slab cycle. When including magnetic
+interactions, we show that the 1D chains have a symmetry protection against
+magnetic perturbations from the iron ions in the slabs, and that the slab size
+determines the type of magnetic order, which is either ferromagnetic or
+antiferromagnetic. Dynamical mean-field theory calculations reveal the
+orbitally selective Mott state of the Fe ions and tendency of conductivity to
+low-dimensional behavior with particular enhancement along the 1D chains.
+Across the series, the decoupling of the chains increases, and so with the
+inherent charge ordering of the slabs, these structures have the potential to
+allow experimental realization of the model system of coupled 1D wires. We
+point out the possibility to stabilize these compounds in the thin-film form
+that, together with a wide range of possible ionic substitutions and fact that
+these compounds are recoverable at ambient pressure, makes them a very
+promising platform to engineer physical systems with interesting
+magnetotransport phenomena, as corroborated by the recent discovery of quantum
+Hall effect in ZrTe$_5$.",2207.14111v1
+2006-08-11,Magnetic Excitations and their energy change available to Superconducting Condensation in Optimally Doped YBa$_2$Cu$_3$O$_{6.95}$,"Understanding the magnetic excitations in high-transition temperature
+(high-$T_c$) copper oxides is important because they may mediate the electron
+pairing for superconductivity. By determining the wavevector ({\bf Q}) and
+energy ($\hbar\omega$) dependence of the magnetic excitations, one can
+calculate the change in the exchange energy available to the superconducting
+condensation energy. For the high-$T_c$ superconductor YBa$_2$Cu$_3$O$_{6+x}$,
+the most prominent feature in the magnetic excitations is the resonance.
+Although the resonance has been suggested to contribute a major part of the
+superconducting condensation, the accuracy of such an estimation has been in
+doubt because the resonance is only a small portion of the total magnetic
+scattering. Here we report an extensive mapping of magnetic excitations for
+YBa$_2$Cu$_3$O$_{6.95}$ ($T_c\approx 93$ K). Using the absolute intensity
+measurements of the full spectra, we estimate the change in the magnetic
+exchange energy between the normal and superconducting states and find it to be
+about 15 times larger than the superconducting condensation energy. Our results
+thus indicate that the change in the magnetic exchange energy is large enough
+to provide the driving force for high-$T_c$ superconductivity in
+YBa$_2$Cu$_3$O$_{6.95}$.",0608280v1
+2006-12-07,"Paramagnetic GaN:Fe and ferromagnetic (Ga,Fe)N - relation between structural, electronic, and magnetic properties","We report on the metalorganic chemical vapor deposition (MOCVD) of GaN:Fe and
+(Ga,Fe)N layers on c-sapphire substrates and their thorough characterization
+via high-resolution x-ray diffraction (HRXRD), transmission electron microscopy
+(TEM), spatially-resolved energy dispersive X-ray spectroscopy (EDS),
+secondary-ion mass spectroscopy (SIMS), photoluminescence (PL), Hall-effect,
+electron-paramagnetic resonance (EPR), and magnetometry employing a
+superconducting quantum interference device (SQUID). A combination of TEM and
+EDS reveals the presence of coherent nanocrystals presumably FexN with the
+composition and lattice parameter imposed by the host. From both TEM and SIMS
+studies, it is stated that the density of nanocrystals and, thus the Fe
+concentration increases towards the surface. In layers with iron content x<0.4%
+the presence of ferromagnetic signatures, such as magnetization hysteresis and
+spontaneous magnetization, have been detected. We link the presence of
+ferromagnetic signatures to the formation of Fe-rich nanocrystals, as evidenced
+by TEM and EDS studies. This interpretation is supported by magnetization
+measurements after cooling in- and without an external magnetic field, pointing
+to superparamagnetic properties of the system. It is argued that the high
+temperature ferromagnetic response due to spinodal decomposition into regions
+with small and large concentration of the magnetic component is a generic
+property of diluted magnetic semiconductors and diluted magnetic oxides showing
+high apparent Curie temperature.",0612200v2
+2011-06-24,Magnetic dichroism in angular-resolved hard X-ray photoelectron spectroscopy from buried layers,"This work reports the measurement of magnetic dichroism in angular-resolved
+photoemission from in-plane magnetized buried thin films. The high bulk
+sensitivity of hard X-ray photoelectron spectroscopy (HAXPES) in combination
+with circularly polarized radiation enables the investigation of the magnetic
+properties of buried layers. HAXPES experiments with an excitation energy of 8
+keV were performed on exchange-biased magnetic layers covered by thin oxide
+films. Two types of structures were investigated with the IrMn exchange-biasing
+layer either above or below the ferromagnetic layer: one with a CoFe layer on
+top and another with a Co$_2$FeAl layer buried beneath the IrMn layer. A
+pronounced magnetic dichroism is found in the Co and Fe $2p$ states of both
+materials. The localization of the magnetic moments at the Fe site conditioning
+the peculiar characteristics of the Co$_2$FeAl Heusler compound, predicted to
+be a half-metallic ferromagnet, is revealed from the magnetic dichroism
+detected in the Fe $2p$ states.",1106.4976v1
+2012-06-29,Laser spectroscopy of finite size and covering effects in magnetite nanoparticles,"The experiments on the impact of the size of magnetite clusters on various
+magnetic properties (magnetic moment, Curie temperature, blocking temperature
+etc.) have been carried out. The methods of magnetic separation, centrifuging
+of water suspensions of biocompatible iron oxide nanoparticles (NPs) allow
+producing fractions with diameter of nanoparticles in the range of 4{\div}22
+nm. The size of NPs are controlled by the methods of dynamic light scattering
+(DLS), transmission electron microscopy (TEM) and atomic force microscopy
+(AFM). For the first time the DLS method is applied in real time to control the
+size during the process of the separation of the NPs in aqueous suspensions.
+The changes of the size of NPs cause a shift in the Curie temperature and in
+the changes in the specific magnetic properties of the iron NPs. The
+experimental data is interpreted on the basis of Monte Carlo simulations for
+the classical Heisenberg model with different bulk and surface magnetic
+moments. It is demonstrated experimentally and by theoretical modeling that
+magnetic properties of magnetite NPs are determined not only by their sizes,
+but also by the their surface spin states, while both growing and falling
+dependences of the magnetic moment (per Fe3O4 formula unit) being possible,
+depending on the number of magnetic atoms in the nanoparticle. Both NPs clean
+and covered with a bioresorbable layer clusters have been investigated.",1206.6985v5
+2014-08-12,Magnetic properties of geometrically frustrated SrGd2O4,"A study of the magnetic properties of the frustrated rare earth oxide SrGd2O4
+has been completed using bulk property measurements of magnetization,
+susceptibility and specific heat on single crystal samples. Two zero-field
+phase transitions have been identified at 2.73 and 0.48 K. For the field, H,
+applied along the a and b axes, a single boundary is identified that delineates
+the transition from a low field, low temperature magnetically ordered regime to
+a high field, high temperature paramagnetic phase. Several field-induced
+transitions, however, have been observed with H || c. The measurements have
+been used to map out the magnetic phase diagram of SrGd2O4, suggesting that it
+is a complex system with several competing magnetic interactions. The
+low-temperature magnetic behavior of SrGd2O4 is very different compared to the
+other SrLn2O4 (Ln = Lanthanide) compounds, even though all of the SrLn2O4
+compounds are isostructural, with the magnetic ions forming a low-dimensional
+lattice of zigzag chains that run along the c axis. The differences are likely
+to be due to the fact that in the ground state Gd3+ has zero orbital angular
+momentum and therefore the spin-orbit interactions, which are crucial for other
+SrLn2O4 compounds, can largely be neglected. Instead, given the relatively
+short Gd3+-Gd3+ distances in SrGd2O4, dipolar interactions must be taken into
+account for this antiferromagnet alongside the Heisenberg exchange terms.",1408.2771v1
+2015-01-13,Strain-Induced Extrinsic High-Temperature Ferromagnetism in the Fe-Doped Hexagonal Barium Titanate,"Diluted magnetic semiconductors possessing intrinsic static magnetism at high
+temperatures represent a promising class of multifunctional materials with high
+application potential in spintronics and magneto-optics. In the hexagonal
+Fe-doped diluted magnetic oxide, 6H-BaTiO$_{3-\delta}$, room-temperature
+ferromagnetism has been previously reported. Ferromagnetism is broadly accepted
+as an intrinsic property of this material, despite its unusual dependence on
+doping concentration and processing conditions. However, the here reported
+combination of bulk magnetization and complementary in-depth local-probe
+electron spin resonance and muon spin relaxation measurements, challenges this
+conjecture. While a ferromagnetic transition occurs around 700 K, it does so
+only in additionally annealed samples and is accompanied by an extremely small
+average value of the ordered magnetic moment. Furthermore, several additional
+magnetic instabilities are detected at lower temperatures. These coincide with
+electronic instabilities of the Fe-doped 3C-BaTiO$_{3-\delta}$ pseudocubic
+polymorph. Moreover, the distribution of iron dopants with frozen magnetic
+moments is found to be non-uniform. Our results demonstrate that the intricate
+static magnetism of the hexagonal phase is not intrinsic, but rather stems from
+sparse strain-induced pseudocubic regions. We point out the vital role of
+internal strain in establishing defect ferromagnetism in systems with competing
+structural phases.",1501.02938v1
+2015-07-07,Hour-glass magnetic excitations induced by nanoscopic phase separation in cobalt oxides La$_{2-x}$Sr$_x$CoO$_4$,"The magnetic excitations in the cuprate superconductors might be essential
+for an understanding of high-temperature superconductivity. In these cuprate
+superconductors the magnetic excitation spectrum resembles an hour-glass and
+certain resonant magnetic excitations within are believed to be connected to
+the pairing mechanism which is corroborated by the observation of a universal
+linear scaling of superconducting gap and magnetic resonance energy. So far,
+charge stripes are widely believed to be involved in the physics of hour-glass
+spectra. Here we study an isostructural cobaltate that also exhibits an
+hour-glass magnetic spectrum. Instead of the expected charge stripe order we
+observe nano phase separation and unravel a microscopically split origin of
+hour-glass spectra on the nano scale pointing to a connection between the
+magnetic resonance peak and the spin gap originating in islands of the
+antiferromagnetic parent insulator. Our findings open new ways to theories of
+magnetic excitations and superconductivity in cuprate superconductors.",1507.01783v1
+2019-05-25,Multireference Ab Initio Studies of Magnetic Properties of Terbium-Based Single-Molecule Magnets,"We investigate how different chemical environment influences magnetic
+properties of terbium(III) (Tb)-based single-molecule magnets (SMMs), using
+first-principles relativistic multireference methods. Recent experiments showed
+that Tb-based SMMs can have exceptionally large magnetic anisotropy and that
+they can be used for experimental realization of quantum information
+applications, with a judicious choice of chemical environment. Here, we perform
+complete active space self-consistent field (CASSCF) calculations including
+relativistic spin-orbit interaction (SOI) for representative Tb-based SMMs such
+as TbPc$_2$ and TbPcNc in three charge states. We calculate low-energy
+electronic structure from which we compute the Tb crystal-field parameters and
+construct an effective pseudospin Hamiltonian. Our calculations show that
+ligand type and fine points of molecular geometry do not affect the zero-field
+splitting, while the latter varies weakly with oxidation number. On the other
+hand, higher-energy levels have a strong dependence on all these
+characteristics. For neutral TbPc$_2$ and TbPcNc molecules, the Tb magnetic
+moment and the ligand spin are parallel to each other and the coupling strength
+between them does not depend much on ligand type and details of atomic
+structure. However, ligand distortion and molecular symmetry play a crucial
+role in transverse crystal-field parameters which lead to tunnel splitting. The
+tunnel splitting induces quantum tunneling of magnetization by itself or by
+combining with other processes. Our results provide insight into mechanisms of
+magnetization relaxation in the representative Tb-based SMMs.",1905.10635v1
+2018-06-22,"Magnetic clustering, half-moons, and shadow pinch points as signals of a proximate Coulomb phase in frustrated Heisenberg magnets","We study the formation of magnetic clusters in frustrated magnets in their
+cooperative paramagnetic regime. For this purpose, we consider the
+$J_1$-$J_2$-$J_3$ classical Heisenberg model on kagome and pyrochlore lattices
+with $J_2 = J_3=J$. In the absence of farther-neighbor couplings, $J=0$, the
+system is in the Coulomb phase with magnetic correlations well characterized by
+pinch-point singularities. Farther-neighbor couplings lead to the formation of
+magnetic clusters, which can be interpreted as a counterpart of
+topological-charge clusters in Ising frustrated magnets [T. Mizoguchi, L. D. C.
+Jaubert and M. Udagawa, Phys. Rev. Lett. {\bf 119}, 077207 (2017)]. The
+concomitant static and dynamical magnetic structure factors, respectively
+$\mathcal{S}({\bm{q}})$ and $\mathcal{S}({\bm{q}},\omega)$, develop half-moon
+patterns. As $J$ increases, the continuous nature of the Heisenberg spins
+enables the half-moons to coalesce into connected `star' structures spreading
+across multiple Brillouin zones. These characteristic patterns are a dispersive
+complement of the pinch point singularities, and signal the proximity to a
+Coulomb phase. Shadows of the pinch points remain visible at finite energy,
+$\omega$. This opens the way to observe these clusters through (in)elastic
+neutron scattering experiments. The origin of these features are clarified by
+complementary methods: large-$N$ calculations, semi-classical dynamics of the
+Landau-Lifshitz equation, and Monte Carlo simulations. As promising candidates
+to observe the clustering states, we revisit the origin of ""spin molecules""
+observed in a family of spinel oxides $AB_2$O$_4$ ($A=$ Zn, Hg, Mg, $B=$ Cr,
+Fe).",1806.08534v2
+2018-07-04,Critical behavior in itinerant ferromagnet SrRu$_{1-x}$Ti$_x$O$_3$,"SrRuO$_3$ presents a rare example of ferromagnetism among the 4$d$ based
+oxides. While the nature of magnetic state in SrRuO$_3$ is mostly believed to
+be of itinerant type, recent studies suggest a coexistence of both itinerant
+and localized model of magnetism in this material. Here, we have investigated
+the evolution of magnetic state in doped SrRu$_{1-x}$Ti$_x$O$_3$ through
+studying the critical behavior using standard techniques such as, modified
+Arrott plot, Kouvel-Fisher plot and critical isotherm analysis across the
+magnetic transition temperature $T_c$. The substitution of nonmagnetic
+Ti$^{4+}$ (3$d^{0}$) for Ru$^{4+}$ (4$d^4$) would simply dilute the magnetic
+system apart from modifying the electron correlation effect and the density of
+states at Fermi level. Surprisingly, $T_c$ does not change with $x$. Moreover,
+our analysis show the exponent $\beta$ related to spontaneous magnetization
+increases while the exponents $\gamma$ and $\delta$ related to initial inverse
+susceptibility and critical magnetization, respectively decrease with Ti
+substitution. The estimated exponents do not match with any established
+theoretical models for universality classes, however, the exponent obey the
+Widom relation and the scaling behavior. Interestingly, this particular
+evolution of exponents in present series has similarity with that in
+isoelectronic doped Sr$_{1-x}$Ca$_x$RuO$_3$. We believe that site dilution by
+Ti leads to formation magnetic clusters which causes this specific changes in
+critical exponents.",1807.01445v1
+2021-05-11,Spin-dependent magnetism and superparamagnetic contribution to the magnetocaloric effect of non-stoichiometric manganite nanoparticles,"Despite extensive researches on manganites owing to widespread use in modern
+electronics, this class of metal oxides does not cease to surprise with its
+unique properties and new phenomena. Here we have studied structural and
+magnetic properties of non-Heisenberg manganite nanoparticles with a strong
+spin-electron coupling. During transition from low temperature ferromagnetic to
+high temperature paramagnetic state, the change in charge, valence and spin
+(magnetic moment) with the localization of eg-electrons on the manganese ions
+have been detected. With decrease in a temperature, the overstated effective
+magnetic moment of Mn ions in paramagnetic phase is reduced dramatically
+testifying to spin-dependent magnetism. The critical behavior of magnetization
+with determination of critical parameters near second-order phase transition
+has been studied comprehensively. Based on unusual behavior of temperature and
+field dependences of magnetic entropy change under different magnetic field, an
+additional influence of superparamagnetism of nanoparticles on the
+magnetocaloric effect has been found.",2105.04831v1
+2021-07-23,Intermixing Induced Anisotropy Variations in CoB-based Chiral Multilayer Films,"We examine the atomic intermixing phenomenon in three distinct amorphous
+CoB-based multilayer thin film platforms - Pt/CoB/Ir, Ir/CoB/Pt and Pt/CoB/MgO
+- which are shown to stabilise room-temperature chiral magnetic textures.
+Intermixing occurs predominantly between adjacent metallic layers. Notably, it
+is stack-order dependent, and particularly extensive when Ir sits atop CoB.
+Intermixing induced variations in magnetic properties are ascribed to the
+formation of magnetic dead layer arising from CoIr alloying in the metallic
+stacks. It also produces systematic variations in saturation magnetization, by
+as much as 30%, across stacks. Crucially, the resulting crossover CoB thickness
+for the transition from perpendicular to in-plane magnetic anisotropy differs
+by more than 2x across the stacks. Finally, with thermal annealing treatment
+over moderate temperatures of 150-300 degree Celsius, the magnetic anisotropy
+increases monotonically across all stacks, coupled with discernibly larger Hc
+for the metallic stacks. These are attributed to thermally induced CoPt
+alloying and MgO crystallization in the metallic and oxide stacks,
+respectively. Remarkably, the CoB in the Pt/CoB/MgO stacks retains its
+amorphous nature after annealing. Our results set the stage for harnessing the
+collective attributes of amorphous CoB-based material platforms and associated
+annealing processes for modulating magnetic interactions, enabling the tuning
+of chiral magnetic texture properties in ambient conditions.",2107.11034v1
+2014-04-21,"Unconventional magnetism in the spin-orbit driven Mott insulators Ba3MIr2O9 (M=Sc,Y)","We have carried out detailed bulk and local probe studies on the hexagonal
+oxides Ba3MIr2O9 (M=Sc,Y) where Ir is expected to have a fractional oxidation
+state of +4.5. In the structure, Ir-Ir dimers are arranged in an edge shared
+triangular network parallel to the ab plane. Whereas only weak anomalies are
+evident in the susceptibility data, clearer anomalies are present in the heat
+capacity data. Our 45Sc nuclear magnetic resonance (NMR) lineshape (first order
+quadrupole split) is symmetric at room temperature but becomes progressively
+asymmetric with decreasing temperatures. This is suggestive of distortions in
+the structure which could arise from progressive tilt/rotation of the IrO6
+octahedra with a decrease in temperature T. The 45Sc NMR spectral weight shifts
+near the reference frequency with decreasing T indicating the development of
+magnetic singlet regions. Around 10K, a significant change in the spectrum
+takes place with a large intensity appearing near the reference frequency but
+with the spectrum remaining multi-peak. It appears from our 45Sc NMR data that
+in Ba3ScIr2O9 significant disorder is still present below 10K. In the case of
+Ba3YIr2O9, the 89Y NMR spectral lines are asymmetric at high temperatures but
+become nearly symmetric (single magnetic environment) below T~70K. Our 89Y
+spectra and T1 measurements confirm the onset of long range ordering (LRO) from
+a bulk of the sample at 4K in this compound. Our results suggest that Ba3YIr2O9
+might be structurally distorted at room temperature (via, for example,
+tilt/rotations of the IrO6 octahedra) but becomes progressively a regular
+triangular lattice with decreasing T. The effective magnetic moments and
+magnetic entropy changes are strongly reduced in Ba3YIr2O9 as compared to those
+expected for a S=1/2 system. Similar effects have been found in other iridates
+which naturally have strong spin-orbit coupling (SOC).",1404.5262v1
+2019-10-07,Structural and magnetic properties of 3d transition metal oxide chains on the (001) surfaces of Ir and Pt,"We present a survey of the structural and magnetic properties of submonolayer
+transition metal dioxides on the (001) surfaces of the heavy face-centered
+cubic (fcc) noble metals Ir and Pt performed by spin-averaged scanning
+tunneling microscopy (STM) and spin-polarized (SP-)STM. Our STM results confirm
+that deposition of Co, Fe, Mn, and Cr on the (2 {\times} 1)
+oxygen-reconstructed Ir(001) surface leads to the formation of quasi
+one-dimensional chains with a (3 {\times} 1) unit cell. As recently predicted
+by density functional theory [Ferstl et al., Phys. Rev. Lett. 117, 046101
+(2016)], our SP-STM images of FeO2 and MnO2 on Ir(001) show a two-fold
+periodicity along the chains which is characteristic for an antiferromagnetic
+coupling along the chains. In addition, these two materials also exhibit
+spontaneous, permanent, and long-range magnetic coupling across the chains.
+Whereas we find a ferromagnetic inter-chain coupling for FeO2/Ir(001), the
+magnetic coupling of MnO2 on Ir(001) appears to be a non-collinear 120{\deg}
+spin spiral, resulting in a (9 {\times} 2) magnetic unit cell. On Pt(001)
+patches of (3 {\times} 1)-reconstructed oxide chains could only be prepared by
+transition metal (Co, Fe, and Mn) deposition onto the cold substrate and
+subsequent annealing in an oxygen atmosphere. Again SP-STM on MnO2/Pt(001)
+reveals a very large, (15 {\times} 2) magnetic unit cell which can tentatively
+be explained by a commensurate 72{\deg} spin spiral. Large scale SP-STM images
+reveal a long wavelength spin rotation along the MnO2 chain.",1910.02707v1
+2021-04-12,Designer Magnetism in High Entropy Oxides,"Disorder can have a dominating influence on correlated and quantum materials
+leading to novel behaviors which have no clean limit counterparts. In magnetic
+systems, spin and exchange disorder can provide access to quantum criticality,
+frustration, and spin dynamics, but broad tunability of these responses and a
+deeper understanding of strong limit disorder is lacking. In this work, we
+demonstrate that high entropy oxides present an unexplored route to designing
+quantum materials in which the presence of strong local compositional disorder
+hosted on a positionally ordered lattice can be used to generate highly tunable
+emergent magnetic behavior--from macroscopically ordered states to
+frustration-driven dynamic spin interactions. Single crystal
+La(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 films are used as a structurally uniform model
+system hosting a magnetic sublattice with massive microstate disorder in the
+form of site-to-site spin and exchange type inhomogeneity. A classical
+Heisenberg model is found to be sufficient to describe how compositionally
+disordered systems can paradoxically host long-range magnetic uniformity and
+demonstrates that balancing the populating elements based on their discrete
+quantum parameters can be used to give continuous control over ordering types
+and critical temperatures. Theory-guided experiments show that composite
+exchange values derived from the complex mix of microstate interactions can be
+used to design the required compositional parameters for a desired response.
+These predicted materials are synthesized and found to possess an incipient
+quantum critical point when magnetic ordering types are designed to be in
+direct competition; this leads to highly controllable exchange bias sensitivity
+in the monolithic single crystal films previously accessible only in
+intentionally designed bilayer heterojunctions.",2104.05552v2
+2021-05-26,Magnetic Particle Spectroscopy (MPS) with One-stage Lock-in Implementation for Magnetic Bioassays with Improved Sensitivities,"In recent years, magnetic particle spectroscopy (MPS) has become a highly
+sensitive and versatile sensing technique for quantitative bioassays. It relies
+on the dynamic magnetic responses of magnetic nanoparticles (MNPs) for the
+detection of target analytes in liquid phase. There are many research studies
+reporting the application of MPS for detecting a variety of analytes including
+viruses, toxins, and nucleic acids, etc. Herein, we report a modified version
+of MPS platform with the addition of a one-stage lock-in design to remove the
+feedthrough signals induced by external driving magnetic fields, thus capturing
+only MNP responses for improved system sensitivity. This one-stage lock-in MPS
+system is able to detect as low as 781 ng multi-core Nanomag50 iron oxide MNPs
+(micromod Partikeltechnologie GmbH) and 78 ng single-core SHB30 iron oxide MNPs
+(Ocean NanoTech). In addition, using a streptavidin-biotin binding system as a
+proof-of-concept, we show that these single-core SHB30 MNPs can be used for
+Brownian relaxation-based bioassays while the multi-core Nanomag50 cannot be
+used. The effects of MNP amount on the concentration dependent response
+profiles for detecting streptavidin was also investigated. Results show that by
+using lower concentration/amount of MNPs, concentration-response curves shift
+to lower concentration/amount of target analytes. This lower
+concentrationresponse indicates the possibility of improved bioassay
+sensitivities by using lower amounts of MNPs.",2105.12718v1
+2021-09-10,Giant shifts of crystal-field excitations with temperature as consequence of internal magnetic exchange fields,"Crystal-field excitations, for example in transition-metal oxides where a
+rare-earth element is used as a spacer between the transition-metal-oxide
+tetrahedra and octahedra, are assumed to be extremely robust with respect to
+external perturbations such as temperature. Using inelastic neutron scattering
+experiments, a giant shift of the energy of the lowest crystal-field excitation
+of Er3+ (4I15/2) in ErFeO3 from 0.30(2) meV to 0.75(2) meV was measured below
+the magnetic-ordering temperature of erbium at 4.1 K. Quantum-mechanical
+point-charge calculations of the crystal-field levels indicate that the shift
+is caused by the internal magnetic field created by the erbium spins
+themselves, which causes a Zeeman splitting of the erbium 4f electronic levels,
+and therefore a change in the energies of crystal-field transitions. To verify
+this explanation, the effect of an external magnetic field on the crystal-field
+excitations was measured by inelastic neutron scattering and compared to the
+field-dependent point-charge calculations. The existence of an internal
+magnetic exchange interaction will have implications for a deeper understanding
+of a broader group of phenomena such as multiferroic properties or spin
+frustration, which are a consequence of various competing electronic and
+magnetic exchange interactions.",2109.04610v2
+1996-03-07,Electronic and Magnetic Structure of LaCuO$_{2.5}$,"The recently-discovered ``ladder'' compound LaCuO$_{2.5}$ has been found to
+admit hole doping without altering its structure of coupled copper oxide
+ladders. While susceptibility measurements on the parent compound suggest a
+spin gap and a spin-liquid state, NMR results indicate magnetic order at low
+temperatures. These seemingly contradictory results may be reconciled if in
+fact the magnetic state is near the crossover from spin liquid to
+antiferromagnet, and we investigate this possibility. From a tight-binding fit
+to the valence LDA bandstructure, we deduce that the strength of the
+interladder hopping term is approximately half that of intraladder hopping,
+showing that the material is three-dimensional in character. A mean-field
+treatment of the insulating magnetic state gives a spin-liquid phase whose spin
+gap decreases with increasing interladder coupling, vanishing (signalling a
+transition to the ordered phase) at a value somewhat below that obtained for
+LaCuO$_{2.5}$. The introduction of an on-site repulsion term, $U$, to the band
+scheme causes a transition to an antiferromagnetic insulator for rather small
+but finite values of $U$, reflecting the predominance of (one-dimensional)
+ladder behavior, and an absence of any special nesting features.",9603054v2
+1996-11-20,Spin-dependent tunneling in metal-insulator-narrow gap semiconductor structures in a magnetic field,"We present results of tunneling studies of p-Hg_{1-x}Cd_{x}Te-oxide-Al
+structures with 0.165<x<0.2 in a magnetic field up to 6 T. The tunneling
+conductivity oscillations resulting from the Landau quantization of the energy
+spectrum in the semiconductor volume are investigated. Under an in-plane
+magnetic field the amplitudes of tunneling conductivity maxima connected with
+the tunneling into `a' and `b' spin sublevels are found to differ
+substantionally from one another, and the amplitude ratio varying from
+structure to structure. To understand the cause of this behavior, the tunneling
+conductivity for this magnetic field orientation is calculated taking into
+consideration the multi-band energy spectrum. It is shown that the
+contributions of the different spin-sublevels to the tunneling conductivity are
+dissimilar and the relationship between them depends strongly on the value of
+surface potential.",9611149v1
+1999-01-08,Anisotropy and magnetism of high temperature oxides superconductors,"Phonon or electron mediated weak BCS attraction is enough to have high
+critical temperature if a van Hove anomaly is at work. This could apply to
+electron doped compounds and also to compounds with CuO$_2$ planes overdoped in
+holes, where $T_c$ decreases with increasing doping. If phonons dominate, it
+should lead to an anisotropic but mainly $s$ superconductive gap, as observed
+recently in overdoped LaSrCuO, and probably also in electron doped compounds.
+If electrons dominate, a $d$ gap should develop as observed in a number of
+cases. In the underdoped range, the observed decrease of $T_c$ with hole doping
+can be related in all cases to the development of antiferromagnetic
+fluctuations which produces a magnetic pseudogap, thus lowering the density of
+states at the Fermi level. The observed mainly $d$ superconductive gap then can
+be due to a prevalent superconductive coupling through antiferromagnetic
+fluctuations; it could also possibly be attributed to the same phonon coupling
+as in the overdoped range, now acting on Bloch functions scattered in the
+magnetic pseudogap. More systematic studies of superconductive gap anisotropy
+and of magnetic fluctuations would be in order.",9901065v2
+2000-04-10,Combined Paramagnetic and Diamagnetic Response of YBCO,"It has been predicted that the zero frequency density of states of YBCO in
+the superconducting phase can display interesting anisotropy effects when a
+magnetic field is applied parallel to the copper-oxide planes, due to the
+diamagnetic response of the quasi-particles. In this paper we incorporate
+paramagnetism into the theory and show that it lessens the anisotropy and can
+even eliminate it altogether. At the same time paramagnetism also changes the
+scaling with the square root of the magnetic field first deduced by Volovik
+leading to an experimentally testable prediction. We also map out the analytic
+structure of the zero frequency density of states as a function of the
+diamagnetic and paramagnetic energies. At certain critical magnetic field
+values we predict kinks as we vary the magnetic field. However these probably
+lie beyond currently accessible field strengths.",0004152v1
+2000-07-06,Non-Langevin behaviour of the uncompensated magnetisation in nanoparticles of artificial ferritin,"The magnetic behaviour of nanoparticles of antiferromagnetic ferritin has
+been investigated by 57Fe Mossbauer absorption spectroscopy and magnetisation
+measurements, in the temperature range 2.5K-250K and with magnetic fields up to
+7T. Samples containing nanoparticles with an average number of Fe atoms ranging
+from 400 to 2500 were studied. The value of the anisotropy energy per unit
+volume was determined and found to be in the range 3-6 10**5 ergs/cm3, which is
+a value typical for ferric oxides. By comparing the results of the two
+experimental methods at large field, we show that, contratry to what is
+currently assumed, the uncompensated magnetisation of the feritin cores in the
+superparamagnetic regime does not follow a Langevin law. For magnetic fields
+below the spin-flop field, we propose an approximate law for the field and
+temperature variation of the uncompensated magnetisation which has so far never
+been applied in antiferromagnetic systems. This approach should more generally
+hold for randomly oriented antiferro- magnetic nanoparticles systems with weak
+uncompensated moments.",0007087v2
+2000-11-06,Thermodynamics of d-wave superconductors in a magnetic field,"We investigate the thermodynamic properties of a two-dimensional d-wave
+superconductor in the vortex state using a semiclassical approach, and argue
+that such an approach is valid for the analysis of the experimental data on
+high-temperature superconductors. We develop a formalism where the spatial
+average of a physical quantity is written as an integral over the probability
+density of the Doppler shift, and evaluate this probability density for several
+model cases. The approach is then used to analyse the behavior of the specific
+heat and the NMR spin-lattice relaxation rate in a magnetic field. We compare
+our results with the experimental measurements, and explain the origin of the
+discrepancy between the results from different groups. We also address the
+observability of the recently predicted fourfold oscillations of the specific
+heat for the magnetic field parallel to the copper oxide planes. We consider
+both the orbital and the Zeeman effects, and conclude that at experimentally
+relevant temperatures Zeeman splitting does not appreciably reduce the
+anisotropy, although it does change the field dependence of the anisotropic
+specific heat. We predict a scaling law for the non-exponentially decaying NMR
+magnetization, and discuss different approaches to the effective relaxation
+rate.",0011091v1
+2001-02-27,A new class of magnetic materials: Sr2FeMoO6 and related compounds,"Ordered double perovskite oxides of the general formula, A2BB'O6, have been
+known for several decades to have interesting electronic and magnetic
+properties. However, a recent report of a spectacular negative
+magnetoresistance effect in a specific member of this family, namely Sr2FeMoO6,
+has brought this class of compounds under intense scrutiny. It is now believed
+that the origin of magnetism in this class of compounds is based on a novel
+kinetically-driven mechanism. This new mechanism is also likely to be
+responsible for the unusually high temperature ferromagnetism in several other
+systems, such as dilute magnetic semiconductors, as well as in various
+half-metallic ferromagnetic systems, such as Heussler alloys.",0102502v1
+2003-03-11,Effects of hydrostatic pressure on the magnetic susceptibility of ruthenium oxide Sr3Ru2O7: Evidence for pressure-enhanced antiferromagnetic instability,"Hydrostatic pressure effects on the temperature- and magnetic field
+dependencies of the in-plane and out-of-plane magnetization of the bi-layered
+perovskite Sr3Ru2O7 have been studied by SQUID magnetometer measurements under
+a hydrostatic helium-gas pressure. The anomalously enhanced low-temperature
+value of the paramagnetic susceptibility has been found to systematically
+decrease with increasing pressure. The effect is accompanied by an increase of
+the temperature Tmax of a pronounced peak of susceptibility. Thus,
+magnetization measurements under hydrostatic pressure reveal that the lattice
+contraction in the structure of Sr3Ru2O7 promotes antiferromagnetism and not
+ferromagnetism, contrary to the previous beliefs. The effects can be explained
+by the enhancement of the inter-bi-layer antiferromagnetic spin coupling,
+driven by the shortening of the superexchange path, and suppression, due to the
+band-broadening effect, of competing itinerant ferromagnetic correlations.",0303199v1
+2003-04-18,Magnetic field-induced Landau Fermi Liquid in high-T_c metals,"We consider the behavior of strongly correlated electron liquid in
+high-temperature superconductors within the framework of the fermion
+condensation model. We show that at low temperatures the normal state recovered
+by the application of a magnetic field larger than the critical field can be
+viewed as the Landau Fermi liquid induced by the magnetic field. In this state,
+the Wiedemann-Franz law and the Korringa law are held and the elementary
+excitations are the Landau Fermi Liquid quasiparticles. Contrary to what might
+be expected from the Landau theory, the effective mass of quasiparticles
+depends on the magnetic field. The recent experimental verifications of the
+Wiedemann-Franz law in heavily hole-overdoped, overdoped and optimally doped
+cuprates and the verification of the Korringa law in the electron-doped
+copper-oxide superconductor strongly support the existence of fermion
+condensate in high-T_c metals.",0304432v2
+2003-08-28,Spurious magnetism in high-Tc superconductor,"One challenge in condensed-matter physics is to unravel the interplay between
+magnetism and superconductivity in copper oxides with a high critical
+temperature (Tc). Kang et al. claim to have revealed a quantum phase transition
+from the superconducting to an antiferromagnetic state in the electron-doped
+material Nd2-xCexCuO4 (NCCO) based on the observation of magnetic-field-induced
+neutron scattering intensity at (1/2,1/2,0), (1/2,0,0), and related
+reflections. Here we argue that the observed magnetic intensity is due to a
+secondary phase of (Nd,Ce)2O3. We therefore contend that the effect is spurious
+and not intrinsic to superconducting NCCO.",0308607v2
+2003-09-10,Diagonal Antiferromagnetic Easy Axis in Lightly Hole Doped Y_{1-x}Ca_xBa_2Cu_3O_6,"Hole induced changes in the antiferromagnetic structure of a lightly Ca doped
+Gd:Y_{1-x}Ca_xBa_2Cu_3O_6 copper oxide single crystal with x~0.008 is
+investigated by Gd3+ electron spin resonance. Holes do not localize to Ca2+
+ions above 2.5 K since the charge distribution and spin susceptibility next to
+the Ca2+ are independent of temperature. Both hole doped and pristine crystals
+are magnetically twinned with an external magnetic field dependent
+antiferromagnetic domain structure. Unlike the undoped crystal, where the easy
+magnetic axis is along [100] at all temperatures, the easy direction in the
+hole doped crystal is along the [110] diagonal at low temperatures and changes
+gradually to the [100] direction between 10 K and 100 K. The transition is
+tentatively attributed to a magnetic anisotropy introduced by hole ordering.",0309258v1
+2004-03-17,Universal Dispersive Excitations in the High-Temperature Superconductors,"High-resolution neutron scattering experiments on optimally doped
+La$_{2-x}$Sr$_x$CuO$_4$ have been performed which reveal that the magnetic
+excitations are dispersive. The dispersion is found to be the same as in the
+YBa$_2$Cu$_3$O$_{6+x}$ family, and is quantitatively related to that observed
+with charge sensitive probes. The excitations are also found to broaden rapidly
+with increasing energy, forming a continuum at higher energy, and bear a
+remarkable resemblance to multi-particle excitations observed in
+low-dimensional antiferromagnets and some magnetic metals. The magnetic
+correlations are two dimensional, and so rule out the simplest scenarios where
+the copper oxide planes are subdivided into weakly interacting one-dimensional
+magnets.",0403439v2
+2004-03-19,Charge dynamics and Kondo effect in single electron traps in field effect transistors,"We study magneto-electric properties of single electron traps in
+metal-oxide-semiconductor field effect transistors. Using a microscopic
+description of the system based on the single-site Anderson-Holstein model, we
+derive an effective low energy action for the system. The behavior of the
+system is characterized by simultaneous polaron tunneling (corresponding to the
+charging and discharging of the trap) and Kondo screening of the trap spin in
+the singly occupied state. Hence, the obtained state of the system is a hybrid
+between the Kondo regime, typically associated with single electron occupancy,
+and the mixed valence regime, associated with large charge fluctuations. In the
+presence of a strong magnetic field, we demonstrate that the system is
+equivalent to a two level-level system coupled to an Ohmic bath, with a bias
+controlled by the applied magnetic field. Due to the Kondo screening, the
+effect of the magnetic field is significantly suppressed in the singly occupied
+state. We claim that this suppression can be responsible for the experimentally
+observed anomalous magnetic field dependence of the average trap occupancy in
+${\rm Si-Si0_2}$ field effect transistors.",0403491v1
+2004-11-27,Spin-Charge Coupling in lightly doped Nd$_{2-x}$Ce$_{x}$CuO$_4$,"We use neutron scattering to study the influence of a magnetic field on spin
+structures of Nd$_2$CuO$_4$. On cooling from room temperature, Nd$_2$CuO$_4$
+goes through a series of antiferromagnetic (AF) phase transitions with
+different noncollinear spin structures. While a c-axis aligned magnetic field
+does not alter the basic zero-field noncollinear spin structures, a field
+parallel to the CuO$_2$ plane can transform the noncollinear structure to a
+collinear one (""spin-flop"" transition), induce magnetic disorder along the
+c-axis, and cause hysteresis in the AF phase transitions. By comparing these
+results directly to the magnetoresistance (MR) measurements of
+Nd$_{1.975}$Ce$_{0.025}$CuO$_4$, which has essentially the same AF structures
+as Nd$_2$CuO$_4$, we find that a magnetic-field-induced spin-flop transition,
+AF phase hysteresis, and spin c-axis disorder all affect the transport
+properties of the material. Our results thus provide direct evidence for the
+existence of a strong spin-charge coupling in electron-doped copper oxides.",0411694v1
+2005-01-29,Magnetic structural effect in nonequilibrium defective solids,"Scientific study of the effect of structural memory of nonequilibrium
+defective solids about the processing in magnetic field (the magnetic
+structural effect (MSE) was continued in this paper. The study was aimed to
+reveal the universal nature of the MSE, which was investigated in several new
+nonequilibrium defective solids. The results of investigation of the processing
+in the vortical magnetic field (PVMF) and its effect on the structure of the
+natural magnetite Fe3O4 and the SnO2 films were presented. The methods of
+M&#246;ssbauer and X-ray spectroscopy were used. The PVMF reduction of a
+defectiveness of Fe3O4 structure in the magnetite was detected. The MSE was
+also observed in the M&#246;ssbauer spectra of diamagnetic tin oxide SnO2 films
+after the PVMF. One of the possible explanations of the MSE was given in the
+paper.",0501727v1
+2005-02-23,Enhanced magnetic moment and conductive behavior in NiFe2O4 spinel ultrathin films,"Bulk NiFe2O4 is an insulating ferrimagnet. Here, we report on the epitaxial
+growth of spinel NiFe2O4 ultrathin films onto SrTiO3 single-crystals. We will
+show that - under appropriate growth conditions - epitaxial stabilization leads
+to the formation of a spinel phase with magnetic and electrical properties that
+radically differ from those of the bulk material : an enhanced magnetic moment
+(Ms) - about 250% larger - and a metallic character. A systematic study of the
+thickness dependence of Ms allows to conclude that its enhanced value is due to
+an anomalous distribution of the Fe and Ni cations among the A and B sites of
+the spinel structure resulting from the off-equilibrium growth conditions and
+to interface effects. The relevance of these findings for spinel- and, more
+generally, oxide-based heterostructures is discussed. We will argue that this
+novel material could be an alternative ferromagetic-metallic electrode in
+magnetic tunnel junctions.",0502558v1
+2005-04-18,Geometrical Magnetic Frustration in Rare Earth Chalcogenide Spinels,"We have characterized the magnetic and structural properties of the CdLn2Se4
+(Ln = Dy, Ho), and CdLn2S4 (Ln = Ho, Er, Tm, Yb) spinels. We observe all
+compounds to be normal spinels, possessing a geometrically frustrated
+sublattice of lanthanide atoms with no observable structural disorder. Fits to
+the high temperature magnetic susceptibilities indicate these materials to have
+effective antiferromagnetic interactions, with Curie-Weiss temperatures theta ~
+-10 K, except CdYb2S4 for which theta ~ -40 K. The absence of magnetic long
+range order or glassiness above T = 1.8 K strongly suggests that these
+materials are a new venue in which to study the effects of strong geometrical
+frustration, potentially as rich in new physical phenomena as that of the
+pyrochlore oxides.",0504422v2
+2005-04-29,Non-invasive detection of charge-rearrangement in a quantum dot in high magnetic fields,"We demonstrate electron redistribution caused by magnetic field on a single
+quantum dot measured by means of a quantum point contact as non-invasive
+detector. Our device which is fabricated by local anodic oxidation allows to
+control independently the quantum point contact and all tunnelling barriers of
+the quantum dot. Thus we are able to measure both the change of the quantum dot
+charge and also changes of the electron configuration at constant number of
+electrons on the quantum dot. We use these features to exploit the quantum dot
+in a high magnetic field where transport through the quantum dot displays the
+effects of Landau shells and spin blockade. We confirm the internal
+rearrangement of electrons as function of the magnetic field for a fixed number
+of electrons on the quantum dot.",0504777v1
+2005-05-12,"Influence of Ru-doping on structure, defect chemistry, magnetic interaction and carrier motion of the La1-xNaxMnO3+delta manganite","In this work we report a structural, electrical and magnetic characterization
+of the La1-xNaxMn1-yRuyO3+d (LNMRO) system with x = 0.05, 0.15 and y = 0, 0.05,
+0.15, also comprising an investigation of the role of the oxygen content on the
+related redox properties. The experimental investigation has been realized with
+the aid of X-ray powder diffraction, electron microprobe analysis,
+thermogravimetry, electrical resistivity and magnetization measurements, and
+electron paramagnetic resonance. We demonstrate that the effect of ruthenium
+doping on the studied LNMRO compounds is not only directly related to the Ru/Mn
+substitution and to the Ru oxidation state but also indirectly connected to the
+oxygen content in the sample. Our data show that ruthenium addition can improve
+electrical and magnetic properties of non-optimally (low) cation doped
+manganites, causing an increase of the TC value and the insurgence of MR
+effect, as observed for the x = 0.05 and y = 0.05 sample.",0505309v1
+2005-11-12,Universal properties of modulated antiferromagnetic systems,"Magnetism and superconductivity are physical phenomena whose foundations are
+rooted in quantum mechanics and whose technological applications do not cease
+to surprise us. In this article we describe a class of magnetic materials, we
+call modulated antiferromagnetic systems (MAS), that has a prominent
+representative in the copper-oxide high-temperature superconductors. The class,
+however, is not exclusive to these superconductors. Indeed, several materials
+that belong to that class are insulators. The magnetic spectral weight of MAS
+displays the following universal properties: a local intensity maximum
+(resonance peak) at the commensurate antiferromagnetic wave vector; peaks at
+the nearly-antiferromagnetic wave vectors for excitation energies well below
+the resonance, and at wave vectors rotated by 45 degrees for energies above
+resonance. Moreover, we predict an observable rotation by 45 degrees of the
+peaks immediately below the resonance. All these universal signatures,
+condensed in a twisted hour-glass-like spectrum, are merely consequences of the
+unique topological characteristics of the single-particle magnetic dispersion
+relation. We thus provide a unifying scenario that explains the phenomenology
+that has been observed in inelastic neutron scattering experiments of the
+high-temperature superconductors.",0511303v1
+2006-05-04,Magnetic anisotropy of $Co_x Pt_{1-x}$ clusters embedded in matrix: Influences of the cluster chemical composition and the matrix nature,"We report on the magnetic properties of Co$\_x$Pt$\_{1-x}$ clusters embedded
+in various matrices. Using a careful analysis of magnetization curves and ZFC
+susceptibility measurements, we determine the clusters magnetic anisotropy
+energy (MAE) and separate the surface and volume contributions. By comparing
+different chemical compositions, we show that a small amount of Pt (15%)
+induces an important increase in the volume anisotropy with respect to pure Co
+clusters, even in chemically disordered fcc clusters. Comparing the
+measurements of clusters embedded in Nb and MgO matrices, we show that the
+oxide matrix induces an important increase of the surface MAE attributed to the
+formation of an antiferromagnetic CoO shell around the clusters.",0605107v1
+2006-06-09,The magnetotransport properties of La0.7Sr0.3MnO3/BaTiO3 superlattices grown by pulsed laser deposition technique,"We have investigated the magnetotransport properties of La0.7Sr0.3MnO3/BaTiO3
+superlattices, grown on SrTiO3 substrate by pulsed laser deposition technique,
+both with current-in-plane and current-perpendicular-to-the-plane directions.
+Several features indicate the presence of magnetic inhomogeneities at the
+interfaces which is independent of BaTiO3 layer thickness variation. First, the
+magnetic property in the superlattices decreases. Second, a hysteresis in
+magnetoresistance due to the relaxation of the resistive state is observed.
+Third, a threshold under an applied magnetic field in the magnetoresistance is
+seen. Such behaviors are in agreement with the phase separation scenario which
+could be the possible reason for these magnetic inhomogeneities at the
+interfaces. On the contrary, the magnetoresistance with the
+current-perpendicular-to-the-plane direction is mostly attributed to the
+tunneling effect along with the ordering of the spin at the interface. This
+study confirms the importance of the interfaces in superlattices that can be
+used to control novel physical properties in oxide materials.",0606232v1
+2006-07-14,Electric field control of exchange bias in multiferroic epitaxial heterostructures,"The magnetic exchange bias between epitaxial thin films of the multiferroic
+(antiferromagnetic and ferroelectric) hexagonal YMnO3 oxide and a soft
+ferromagnetic (FM) layer is used to couple the magnetic response of the
+ferromagnetic layer to the magnetic state of the antiferromagnetic one. We will
+show that biasing the ferroelectric YMnO3 layer by an appropriate electric
+field allows modifying and controlling the magnetic exchange bias and
+subsequently the magnetotransport properties of the FM layer. This finding may
+contribute to pave the way towards a new generation of electric-field
+controlled spintronics devices.",0607381v1
+2006-11-14,Re-entrant ferromagnetism in a generic class of diluted magnetic semiconductors,"Considering a general situation where a semiconductor is doped by magnetic
+impurities leading to a carrier-induced ferromagnetic exchange coupling between
+the impurity moments, we show theoretically the possible generic existence of
+three ferromagnetic transition temperatures, T_1 > T_2 > T_3, with two distinct
+ferromagnetic regimes existing for T_1 > T > T_2 and T < T_3. Such an
+intriguing re-entrant ferromagnetism, with a paramagnetic phase (T_2 > T > T_3)
+between two ferromagnetic phases, arises from a subtle competition between
+indirect exchange induced by thermally activated carriers in an otherwise empty
+conduction band versus the exchange coupling existing in the impurity band due
+to the bound carriers themselves. We comment on the possibility of observing
+such a re-entrance phenomenon in diluted magnetic semiconductors and magnetic
+oxides.",0611384v1
+2007-01-16,Magnetoelectric coupling in epitaxial orthorhombic YMnO3 thin films,"We have grown epitaxial thin-films of the orthorhombic phase of YMnO3 oxide
+on Nb:SrTiO3(001) substrates and their structure, magnetic and dielectric
+response have been measured. We have found that a substrate-induced strain
+produces an in-plane compression of the YMnO3 unit cell. The
+temperature-dependent magnetization curves display a significant ZFC-FC
+hysteresis at temperatures below the Neel temperature (TN around 40K). The
+dielectric constant increases gradually (up to 26%) below TN and mimics the ZFC
+magnetization curve. We argue that these effects are a manifestation of
+magnetoelectric coupling in thin films and that the magnetic structure of YMnO3
+can be controlled by substrate selection.",0701387v1
+2007-05-19,Spin-Liquid State in the S = 1/2 Hyperkagome Antiferromagnet Na4Ir3O8,"A spinel related oxide, Na4Ir3O8, was found to have a three dimensional
+network of corner shared Ir4+ (t2g^5) triangles. This gives rise to an
+antiferromagnetically coupled S = 1/2 spin system formed on a geometrically
+frustrated hyperkagome lattice. Magnetization M and magnetic specific heat Cm
+data showed the absence of long range magnetic ordering at least down to 2 K.
+The large Cm at low temperatures is independent of applied magnetic field up to
+12 T, in striking parallel to the behavior seen in triangular and kagome
+antiferromagnets reported to have a spin-liquid ground state. These results
+strongly suggest that the ground state of Na4Ir3O8 is a three dimensional
+manifestation of a spin liquid.",0705.2821v2
+2007-05-21,Room temperature spin polarized magnetic semiconductor,"Alternating layers of granular Iron (Fe) and Titanium dioxide
+(TiO$_{2-\delta}$) were deposited on (100) Lanthanum aluminate (LaAlO$_3$)
+substrates in low oxygen chamber pressure using a controlled pulsed laser
+ablation deposition technique. The total thickness of the film was about 200
+nm. The films show ferromagnetic behavior for temperatures ranging from 4 to
+$400 ^oK$. The layered film structure was characterized as p-type magnetic
+semiconductor at $300 ^oK$ with a carrier density of the order of $10^{20}
+/cm^3$. The undoped pure TiO$_{2-\delta}$ film was characterized as an n-type
+magnetic semiconductor. The hole carriers were excited at the interface between
+the granular Fe and TiO$_{2-\delta}$ layers similar to holes excited in the
+metal/n-type semiconductor interface commonly observed in
+Metal-Oxide-Semiconductor (MOS) devices. The holes at the interface were
+polarized in an applied magnetic field raising the possibility that these
+granular MOS structures can be utilized for practical spintronic device
+applications.",0705.2993v1
+2007-05-30,Epitaxial thin films of multiferroic Bi2FeCrO6 with B-site cationic order,"Epitaxial thin films of Bi2FeCrO6 have been synthesized by pulsed laser
+deposition on SrRuO3 on (100)- and (111)-oriented SrTiO3 substrates. Detailed
+X-ray diffraction and cross-section transmission electron microscopy analysis
+revealed a double perovskite crystal structure of the Bi2FeCrO6 epitaxial films
+very similar to that of BiFeO3 along with a particularly noteworthy Fe3+/Cr3+
+cation ordering along the [111] direction. The films contain no detectable
+magnetic iron oxide impurities and have the correct cationic average
+stoichiometry throughout their thickness. They however exhibit a slight
+modulation in the Fe and Cr compositions forming complementary stripe patterns,
+suggesting minor local excess or depletion of Fe and Cr. The epitaxial BFCO
+films exhibit good ferroelectric and piezoelectric properties, in addition to
+magnetic properties at room temperature, as well as an unexpected
+crystallographic orientation dependence of their room temperature magnetic
+properties. Our results qualitatively confirm the predictions made using the
+ab-initio calculations: the double-perovskite structure of Bi2FeCrO6 films
+exhibit a Fe3+/Cr3+ cation ordering and good multiferroic properties, along
+with the unpredicted existence of magnetic ordering at room temperature.",0705.4390v1
+2007-06-19,Probing the Role of the Barrier Layer in Magnetic Tunnel Junction Transport,"Magnetic tunnel junctions with a ferrimagnetic barrier layer have been
+studied to understand the role of the barrier layer in the tunneling process -
+a factor that has been largely overlooked until recently. Epitaxial oxide
+junctions of highly spin polarized La0.7Sr0.3MnO3 and Fe3O4 electrodes with
+magnetic NiMn2O4 (NMO) insulating barrier layers provide a magnetic tunnel
+junction system in which we can probe the effect of the barrier by comparing
+junction behavior above and below the Curie temperature of the barrier layer.
+When the barrier is paramagnetic, the spin polarized transport is dominated by
+interface scattering and surface spin waves; however, when the barrier is
+ferrimagnetic, spin flip scattering due to spin waves within the NMO barrier
+dominates the transport.",0706.2726v2
+2007-08-15,Insulator to semiconductor transition and magnetic properties of the one-dimensional S = 1/2 system In_2VO_5,"We report structural, magnetization, electrical resistivity and nuclear- and
+electron spin resonance data of the complex transition metal oxide In_2VO_5 in
+which structurally well-defined V-O chains are realized. An itinerant character
+of the vanadium d-electrons and ferromagnetic correlations, revealed at high
+temperatures, are contrasted with the insulating behavior and predominantly
+antiferromagnetic exchange between the localized V^{4+} S = 1/2-magnetic
+moments which develop below a certain characteristic temperature T* ~ 120 K.
+Eventually the compound exhibits short-range magnetic order at $T_SRO ~ 20 K.
+We attribute this crossover occurring around T* to the unusual anisotropic
+thermal contraction of the lattice which changes significantly the overlap
+integrals and the character of magnetic intra- and interchain interactions.",0708.2088v1
+2007-09-11,Magnetically asymmetric interfaces in a (LaMnO$_3$)/(SrMnO$_3$) superlattice due to structural asymmetries,"Polarized neutron reflectivity measurements of a ferromagnetic
+[(LaMnO$_3$)$_{11.8}$/(SrMnO$_3$)$_{4.4}$]$_6$ superlattice reveal a modulated
+magnetic structure with an enhanced magnetization at the interfaces where
+LaMnO$_3$ was deposited on SrMnO$_3$ (LMO/SMO). However, the opposite
+interfaces (SMO/LMO) are found to have a reduced ferromagnetic moment. The
+magnetic asymmetry arises from the difference in lateral structural roughness
+of the two interfaces observed via electron microscopy, with strong
+ferromagnetism present at the interfaces that are atomically smooth over tens
+of nanometers. This result demonstrates that atomic-scale roughness can
+destabilize interfacial phases in complex oxide heterostructures.",0709.1715v2
+2008-10-02,Magnetic Modulation in Mechanical Alloyed Cr1.4fe0.6o3 Oxide,"We have synthesized Cr1.4Fe0.6O3 compound through mechanical alloying of
+Cr2O3 and Fe2O3 powders and subsequent thermal annealing. The XRD spectrum, SEM
+picture and microanalysis of EDAX spectrum have been used to understand the
+structural evolution in the alloyed compound. The alloyed samples are matching
+to rhombohedral structure with R3C space group. The observation of a modulated
+magnetic order confirmed a systematic diffusion of Fe atoms into the Cr sites
+of lattice structure. A field induced magnetic behaviour is seen in the field
+dependence of magnetization data of the annealed samples. The behaviour is
+significantly different from the mechanical alloyed samples. The experimental
+results provided the indications of considering the present material as a
+potential candidate for opto-electronic applications.",0810.0439v1
+2009-04-14,Optimizing the flux coupling between a nanoSQUID and a magnetic particle using atomic force microscope nanolithography,"We present results of Niobium based SQUID magnetometers for which the
+weak-links are engineered by the local oxidation of thin films using an Atomic
+Force Microscope (AFM). Firstly, we show that this technique allows the
+creation of variable thickness bridges with 10 nm lateral resolution. Precise
+control of the weak-link milling is offered by the possibility to realtime
+monitor weak-link conductance. Such a process is shown to enhance the magnetic
+field modulation hence the sensitivity of the magnetometer. Secondly, AFM
+lithography is used to provide a precise alignment of NanoSQUID weak-links with
+respect to a ferromagnetic iron dot. The magnetization switching of the
+near-field coupled particle is studied as a junction of the applied magnetic
+field direction.",0904.2100v1
+2009-05-01,Huge ac magnetoresistance in La0.7Sr0.3MnO3 in sub- kilo gauss magnetic fields,"We report dynamical magnetotransport in a ferromagnetic metallic oxide,
+La0.7Sr0.3MnO3 using the ac impedance technique. The temperature dependence of
+the ac resistance(R) and the inductive reactance (X) of the complex impedance
+(Z = R+jX) under different dc bias magnetic fields (Hdc = 0-1 kOe) were studied
+for different frequencies f = 0.1 to 5 MHz of alternating current. The zero
+field R, which decreases smoothly around the Curie temperature TC for f = 100
+kHz, transforms into a peak for f = 0.5-5 MHz. The peak decreases in amplitude,
+broadens and shifts downward in temperature as the bias field increases. A huge
+ac magnetoresistance (= 45 % at f = 2 MHz) in a field of Hdc = 1 kOe is found
+and we attribute it to the magnetic field- induced enhancement in the skin
+depth and concomitant suppression of magnetic fluctuations near TC. Our study
+suggests that radio frequency magnetotransport provides an alternative strategy
+to enhance the magnetoresistance and probe the spin-charge coupling in
+manganites.",0905.0090v1
+2009-07-23,Nature of the Magnetic Order in BaMn2As2,"Neutron diffraction measurements have been performed on a powder sample of
+BaMn2As2 over the temperature T range from 10 K to 675 K. These measurements
+demonstrate that this compound exhibits collinear antiferromagnetic ordering
+below the Neel temperature T_N = 625(1) K. The ordered moment mu = 3.88(4)
+mu_B/Mn at T = 10 K is oriented along the c axis and the magnetic structure is
+G-type, with all nearest-neighbor Mn moments antiferromagnetically aligned. The
+value of the ordered moment indicates that the oxidation state of Mn is Mn^{2+}
+with a high spin S = 5/2. The T dependence of mu suggests that the magnetic
+transition is second-order in nature. In contrast to the closely related
+AFe2As2 (A = Ca, Sr, Ba, Eu) compounds, no structural distortion is observed in
+the magnetically ordered state of BaMn2As2.",0907.4094v2
+2010-03-22,Magnetic excitations of spin and orbital moments in cobalt oxide,"Magnetic and phonon excitations in the antiferromagnet CoO with an unquenched
+orbital angular momentum are studied by neutron scattering. Results of energy
+scans in several Brillouin zones in the (HHL) plane for energy transfers up to
+16 THz are presented. The measurements were performed in the antiferromagnetic
+ordered state at 6 K (well below TN~290 K) as well as in the paramagnetic state
+at 450 K. Several magnetic excitation modes are identified from the dependence
+of their intensity on wavevector and temperature. Within a Hund's rule model
+the excitations correspond to fluctuations of coupled orbital and spin degrees
+of freedom whose bandwidth is controlled by interionic superexchange. The
+different <111> ordering domains give rise to several magnetic peaks at each
+wavevector transfer.",1003.4166v1
+2010-09-23,Ferromagnetic order in aged Co-doped TiO2 anatase nanopowders,"Oxide based diluted magnetic semiconductor (DMS) materials have been a
+subject of increasing interest due to reports of room temperature
+ferromagnetism in several systems and their potential use in the development of
+spintronic devices. However, concerns on the stability of the magnetic
+properties of different DMS systems have been raised. Their magnetic moment is
+often unstable, vanishing with a characteristic decay time of weeks or months,
+which precludes the development of real applications. This paper reports on the
+ferromagnetic properties of two-year-aged Ti1-xCoxO2-{\delta} reduced anatase
+nanopowders with different Co contents (0.03<x<0.10). Aged samples retain
+rather high values of magnetization, remanence and coercivity which provide
+strong evidence for a quite preserved long-range ferromagnetic order. In what
+concern Co segregation, some degree of metastability of the diluted Co doped
+anatase structure could be inferred in the case of the sample with the higher
+Co content.",1009.4671v1
+2010-11-15,Light-induced size changes in BiFeO3 crystals,"Multifunctional oxides are promising materials because of their fundamental
+physical properties as well as their potential in applications1. Among these
+materials, multiferroics exhibiting ferroelectricity and magnetism are good
+candidates for spin electronic applications using the magnetoelectric effect,
+which couples magnetism and ferroelecticity. Furthermore, because
+ferroelectrics are insulators with a reasonable bandgap, photons can
+efficiently interact with electrons leading to photoconduction or photovoltaic
+effects. However, until now, coupling of light with mechanical degrees of
+freedom has been elusive, although ferroelasticity is a well-known property of
+these materials. Here, we report on the observation, for the first time, of a
+substantial visiblelight- induced change in the dimensions of BiFeO3 crystals
+at room temperature. The relative light-induced photostrictive effect is of the
+order of 10e-5 with response times below 0.1s. It depends on the polarization
+of incident light as well as applied magnetic fields. This opens the
+perspective of combining mechanical, magnetic, electric and optical
+functionalities in future generations of remote switchable devices.",1011.3398v1
+2010-11-25,First-principles investigation of the very large Perpendicular Magnetic Anisotropy at Fe|MgO Interfaces,"The perpendicular magnetic anisotropy (PMA) arising at the interface between
+ferromagnetic transition metals and metallic oxides are investigated via
+first-principles calculations. In this work very large values of PMA up to 3
+erg/cm$^2$ at Fe$|$MgO interfaces are reported in agreement with recent
+experiments. The origin of PMA is attributed to overlap between O-$p_z$ and
+transition metal $d_{z^2}$ orbitals hybridized with $d_{xz(yz)}$ orbitals with
+stronger spin-orbit coupling induced splitting around the Fermi level for
+perpendicular magnetization orientation. Furthemore, it is shown that the PMA
+value weakens in case of over- or underoxidation when oxygen $p_z$ and
+transition metal $d_{z^2}$ orbitals overlap is strongly affected by disorder,
+in agreement with experimental observations in magnetic tunnel junctions.",1011.5667v1
+2011-04-07,Integer spin-chain antiferromagnetism of the 4d oxide CaRuO3 with post-perovskite structure,"A quasi-one dimensional magnetism was discovered in the post-perovskite
+CaRuO3 (Ru4+: 4d4, Cmcm), which is iso-compositional with the perovskite CaRuO3
+(Pbnm). An antiferromagnetic spin-chain function with -J/kB = 350 K well
+reproduces the experimental curve of the magnetic susceptibility vs.
+temperature, suggesting long-range antiferromagnetic correlations. The
+anisotropic magnetism is probably owing to the dyz - 2p- dzx and dzx - 2p- dyz
+superexchange bonds along a-axis. The Sommerfeld coefficient of the specific
+heat is fairly small, 0.16(2) mJ mol-1 K-2, indicating that the magnetism
+reflects localized nature of the 4d electrons. As far as we know, this is the
+first observation of an integer (S = 1) spin-chain antiferromagnetism in the 4d
+electron system.",1104.1461v1
+2011-04-25,"Spin canted magnetism, decoupling of charge and spin ordering in NdNiO$_3$","We report detailed magnetization measurements on the perovskite oxide
+NdNiO$_3$. This system has a first order metal-insulator (M-I) transition at
+about 200 K which is associated with charge ordering. There is also a
+concurrent paramagnetic to antiferromagnetic spin ordering transition in the
+system. We show that the antiferromagnetic state of the nickel sublattice is
+spin canted. We also show that the concurrency of the charge ordering and spin
+ordering transitions is seen only while warming up the system from low
+temperature. The transitions are not concurrent while cooling the system
+through the M-I transition temperature. This is explained based on the fact
+that the charge ordering transition is first order while the spin ordering
+transition is continuous. In the magnetically ordered state the system exhibits
+ZFC-FC irreversibilities, as well as history-dependent magnetization and aging.
+Our analysis rules out the possibility of spin-glass or superparamagnetism and
+suggests that the irreversibilities originate from magnetocrystalline
+anisotropy and domain wall pinning.",1104.4766v2
+2011-04-30,Magnetic hydrogels derived from polysaccharides with improved specific power absorption: potential devices for remotely triggered drug delivery,"We report on novel ferrogels derived from polysaccharides (sodium alginate
+and chitosan) with embedded iron oxide nanoparticles synthesized in situ and
+their combination with thermally responsive poly (N-isopropylacrylamide) for
+externally-driven drug release using AC magnetic fields. Samples were
+characterized by Raman spectroscopy, transmission electron microscopy (TEM) and
+magnetic measurements. The obtained nanoparticles were found to be of ca. 10 nm
+average size, showing magnetic properties very close to those of the bulk
+material. The thermal response was measured by power absorption experiments,
+finding specific power absorption (SPA) values between 100-300 W/g, which was
+enough for attaining the lower critical solution temperature (LCST) of the
+polymeric matrix within few minutes. This fast response makes these materials
+good candidates for externally controlled drug release.",1105.0075v1
+2011-09-19,Magnetic field-induced novel insulating phase in 2D superconductors,"DC and finite frequency transport measurements of thin films of amorphous
+indium oxide that were driven through the critical point of
+superconductor-insulator transition by the application of perpendicular
+magnetic field are presented. The observation of non-monotonic dependence of
+resistance on magnetic field in the insulating phase, novel transport
+characteristics near the resistance peak and finite superfluid stiffness in the
+insulating phase are all discussed from the point of view that suggests a
+possible relation between the conduction mechanisms in the superconducting and
+insulating phases. The results are summarized in the form of an experimental
+phase diagram for disordered superconductors in the disorder-magnetic field
+plane.",1109.4087v1
+2012-06-08,Superconductivity with Rashba Spin-Orbit Coupling and Magnetic Field,"Two dimensional electron systems at oxide interfaces are often influenced by
+a Rashba type spin- orbit coupling (SOC), which is tunable by a transverse
+electric field. Ferromagnetism at the interface can simultaneously induce
+strong local magnetic fields. This combination of SOC and magnetism leads to
+asymmetric two-sheeted Fermi surfaces, on which either intra- or inter-band
+pairing is favored. The superconducting order parameters are derived within a
+microscopic pairing model realizing both, the Bardeen-Cooper-Schrieffer
+superconductor with inter-band pairing in the regime of dominating magnetic
+field, and a mixed-parity intra-band pairing state with finite-momentum pairing
+in the regime of dominating SOC. We present a phase diagram for the
+superconducting groundstates and analyze the density of states of the different
+phases. The results are discussed in the context of superconductivity and
+ferromagnetism at LaAlO3-SrTiO3 interfaces.",1206.1816v2
+2013-01-02,Spin-orbital locked magnetic excitations in a half-metallic double perovskite Ba2FeReO6,"We present a powder inelastic neutron scattering study of magnetic
+excitations in Ba$_2$FeReO$_6$, a member of the double perovskite family of
+materials which exhibit half-metallic behavior and high Curie temperatures. We
+find clear evidence of two well-defined dispersing magnetic modes in its low
+temperature ferrimagnetic state. We develop a local moment model, which
+incorporates the interaction of Fe spins with spin-orbit locked magnetic
+moments on Re, and show that this captures our experimental observations. Our
+study further opens up double perovskites as model systems to explore the
+interplay of strong correlations and spin-orbit coupling in 5d transition metal
+oxides.",1301.0327v1
+2013-01-09,High coercivity induced by mechanical milling in cobalt ferrite powders,"In this work we report a study of the magnetic behavior of ferrimagnetic
+oxide CoFe2O4 treated by mechanical milling with different grinding balls. The
+cobalt ferrite nanoparticles were prepared using a simple hydrothermal method
+and annealed at 500oC. The non-milled sample presented coercivity of about 1.9
+kOe, saturation magnetization of 69.5 emu/g, and a remanence ratio of 0.42.
+After milling, two samples attained coercivity of 4.2 and 4.1 kOe, and
+saturation magnetization of 67.0 and 71.4 emu/g respectively. The remanence
+ratio MR/MS for these samples increase to 0.49 and 0.51, respectively. To
+investigate the influence of the microstructure on the magnetic behavior of
+these samples, we used X-ray powder diffraction (XPD), transmission electron
+microscopy (TEM), and vibrating sample magnetometry (VSM). The XPD analysis by
+the Williamson-Hall plot was used to estimate the average crystallite size and
+strain induced by mechanical milling in the samples.",1301.1945v1
+2013-02-26,R-M interactions in R2BaMO5 (R=Y or Gd and M=Cu or Zn),"R2BaMO5 (R = Gd, Y and M = Cu, Zn) oxides have been studied by specific heat,
+dc magnetic susceptibility, and electron paramagnetic resonance (EPR). For one
+member of the series without magnetic moment at M, namely Gd2BaZnO5,
+measurements reveal long range antiferromagnetic order at TN(Gd2BaZnO5) =
+2.3(0.1)K, much lower than the Curie Weiss temperature of {\Theta}=15.9(0.3)K.
+This indicates the existence of competing interactions that introduce a large
+degree of magnetic frustration in the system. For Y2BaCuO5 the Cu Cu
+interactions are responsible for the broad maximum in the magnetic contribution
+to the specific heat centered at 18.5(0.01)K that stretches beyond the
+instrumental limit of 25K. The strong Cu Cu interactions also present in
+Gd2BaCuO5, combined with the Gd-Cu interaction, polarize the Gd sublattice
+giving measurable contributions to the specific heat in the same temperature
+range. In addition, they broaden the Gd EPR line and saturate its integrated
+intensity. The ordering temperature of Gd ions is raised to
+TN(Gd2BaCuO5)=12.0(0.1)K.",1302.6327v1
+2013-06-09,Metallic Interface Emerging at Magnetic Domain Wall of Antiferromagnetic Insulator---Fate of Extinct Weyl Electrons,"Topological insulators, in contrast to ordinary semiconductors, accompany
+protected metallic surfaces described by Dirac-type fermions. Here, we
+theoretically show another emergent two-dimensional metal embedded in the bulk
+insulator is realized at a magnetic domain wall. The domain wall has long been
+studied as ingredients of both old-fashioned and leading-edge spintronics. The
+domain wall here, as an interface of seemingly trivial antiferromagnetic
+insulators, emergently realizes a functional interface preserved by zero modes
+with robust two-dimensional Fermi surfaces, where pyrochlore iridium oxides
+proposed to host condensed-matter realization of Weyl fermions offer such
+examples at low temperatures. The existence of ingap states pinned at domain
+walls, theoretically resembling spin/charge solitons in polyacetylene, and
+protected as the edge of hidden one-dimensional weak Chern insulators
+characterized by a zero-dimensional class A topological invariant, solves
+experimental puzzles observed in R2Ir2O7 with rare earth elements R. The domain
+wall realizes a novel quantum confinement of electrons and embosses a net
+uniform magnetization, which enables magnetic control of electronic interface
+transports beyond semiconductor paradigm.",1306.2022v3
+2013-10-02,Full Control of Magnetism in Manganite Bilayer by Ferroelectric Polarization,"An oxide heterostructure made of manganite bilayers and ferroelectric
+perovskites is predicted to lead to the full control of magnetism when
+switching the ferroelectric polarizations. By using asymmetric polar interfaces
+in the superlattices, more electrons occupy the Mn layer at the $n$-type
+interface side than at the $p$-type side. This charge disproportionation can be
+enhanced or suppressed by the ferroelectric polarization. Quantum model and
+density functional theory calculations reach the same conclusion: a
+ferromagnetic-ferrimagnetic phase transition with maximal change $>90%$ of the
+total magnetization can be achieved by switching the polarization's direction.
+This function is robust and provides full control of the magnetization's
+magnitude, not only its direction, via electrical methods.",1310.0811v1
+2013-12-31,Magnetic quantum ratchet effect in Si-MOSFETs,"We report on the observation of magnetic quantum ratchet effect in
+metal-oxide-semiconductor field-effect-transistors on silicon surface
+(Si-MOSFETs). We show that the excitation of an unbiased transistor by ac
+electric field of terahertz radiation at normal incidence leads to a direct
+electric current between the source and drain contacts if the transistor is
+subjected to an in-plane magnetic field. The current rises linearly with the
+magnetic field strength and quadratically with the ac electric field amplitude.
+It depends on the polarization state of the ac field and can be induced by both
+linearly and circularly polarized radiation. We present the quasi-classical and
+quantum theories of the observed effect and show that the current originates
+from the Lorentz force acting upon carriers in asymmetric inversion channels of
+the transistors.",1401.0135v1
+2014-01-05,Phase-coexistence and glass-like behavior in magnetic and dielectric solids with long range order,"Phase-coexistence in the manganese-oxide compounds or manganites with
+colossal magneto-resistance (CMR) has been generally considered to be an
+inhomogeneous ground state. An alternative explanation of phase-coexistence as
+the manifestation of a disorder-broadened first order magnetic phase transition
+being interrupted by the glasslike arrest of kinetics is now gradually gaining
+ground. This kinetic arrest of a first order phase transitions, between two
+states with long-range magnetic order, has actually been observed in various
+other classes of magnetic materials in addition to the CMR manganites. The
+underlying common features of this kinetic arrest of a first order phase
+transition are discussed in terms of the phenomenology of glasses. The possible
+manifestations of such glass-like arrested states across disorder-influenced
+first order phase transitions in dielectric solids and in multiferroic
+materials, are also discussed.",1401.0891v2
+2014-04-04,Angular and temperature dependence of current induced spin-orbit effective fields in Ta/CoFeB/MgO nanowires,"Current induced spin-orbit effective magnetic fields in
+metal/ferromagnet/oxide trilayers provide a new way to manipulate the
+magnetization, which is an alternative to the conventional current induced spin
+transfer torque arising from noncollinear magnetization. Ta/CoFeB/MgO
+structures are expected to be useful for non-volatile memories and logic
+devices due to its perpendicular anisotropy and large current induced
+spin-orbit effective fields. However many aspects such as the angular and
+temperature dependent phenomena of the effective fields are little understood.
+Here, we evaluate the angular and temperature dependence of the current-induced
+spin-orbit effective fields considering contributions from both the anomalous
+and planar Hall effects. The longitudinal and transverse components of
+effective fields are found to have strong angular dependence on the
+magnetization direction at 300 K. The transverse field decreases significantly
+with decreasing temperature, whereas the longitudinal field shows weaker
+temperature dependence. Our results reveal important features and provide an
+opportunity for a more comprehensive understanding of current induced
+spin-orbit effective fields.",1404.1130v1
+2014-07-02,Induced Ferromagnetism at BiFeO3/YBa2Cu3O7 Interfaces,"Transition metal oxides (TMOs) exhibit many emergent phenomena ranging from
+high-temperature superconductivity and giant magnetoresistance to magnetism and
+ferroelectricity. In addition, when TMOs are interfaced with each other, new
+functionalities can arise, which are absent in individual components. Here, we
+report results from first-principles calculations on the magnetism at the
+BiFeO3/YBa2Cu3O7 interfaces. By comparing the total energy for various magnetic
+spin configurations inside BiFeO3, we are able to show that a metallic
+ferromagnetism is induced near the interface. We further develop an interface
+exchange-coupling model and place the extracted exchange coupling interaction
+strengths, from the first-principles calculations, into a resultant generic
+phase diagram. Our conclusion of interfacial ferromagnetism is confirmed by the
+presence of a hysteresis loop in field-dependent magnetization data. The
+emergence of interfacial ferromagnetism should have implications to electronic
+and transport properties.",1407.0722v1
+2014-11-26,Electrical manipulation of orbital occupancy and magnetic anisotropy in manganites,"Electrical manipulation of lattice, charge, and spin has been realized
+respectively by the piezoelectric effect, field-effect transistor, and electric
+field control of ferromagnetism, bringing about dramatic promotions both in
+fundamental research and industrial production. However, it is generally
+accepted that the orbital of materials are impossible to be altered once they
+have been made. Here we use electric-field to dynamically tune the electronic
+phase transition in (La,Sr)MnO3 films with different Mn^4+/(Mn^3+ + Mn^4+)
+ratios. The orbital occupancy and corresponding magnetic anisotropy of these
+thin films are manipulated by gate voltage in a reversible and quantitative
+manner. Positive gate voltage increases the proportion of occupancy of the
+orbital and magnetic anisotropy that were initially favored by strain
+(irrespective of tensile and compressive), while negative gate voltage reduces
+the concomitant preferential orbital occupancy and magnetic anisotropy. Besides
+its fundamental significance in orbital physics, our findings might advance the
+process towards practical oxide-electronics based on orbital.",1411.7128v1
+2014-12-08,The Phase Diagram in Electron-Doped LCCO,"Superconductors are a striking example of a quantum phenomenon in which
+electrons move coherently over macroscopic distances without scattering. The
+high-temperature superconducting oxides(cuprates) are the most studied class of
+superconductors, composed of two-dimensional CuO2 planes separated by other
+layers which control the electron concentration in the planes. A key unresolved
+issue in cuprates is the relationship between superconductivity and magnetism.
+In this paper, we report a sharp phase boundary of static three-dimensional
+magnetic order in the electron-doped superconductor La2-xCexCuO4-d where small
+changes in doping or depth from the surface switch the material from
+superconducting to magnetic. Using low-energy spin polarized muons, we find
+static magnetism disappears close to where superconductivity begins and well
+below the doping where dramatic changes in the transport properties are
+reported. These results indicate a higher degree of symmetry between the
+electron and hole-doped cuprates than previously thought.",1412.2775v1
+2015-02-06,"First-principles insights into f magnetism, a case study on some magnetic pyrochlores","First-principles calculations are performed to investigate f magnetism in
+A$_2$Ti$_2$O$_7$ (A=Eu, Gd, Tb, Dy, Ho, Er, Yb) magnetic pyrochlore oxides. The
+Hubbard U parameter and the relativistic spin orbit correction is applied for
+more accurate description of the electronic structure of the systems. It is
+argued that the main obstacle for first-principles study of these systems is
+the multi-minima solutions of their electronic configuration. Among the studied
+pyrochlores, Gd$_2$Ti$_2$O$_7$ shows the least multi-minima problem. The
+crystal electric field theory is applied for phenomenological comparison of the
+calculated spin and orbital moments with the experimental data.",1502.01814v1
+2015-03-03,Magnetic Fields of Uranus and Neptune: Metallic Fluid Hydrogen,"The magnetic fields of the Ice Giant Planets Uranus and Neptune (U/N) are
+unique in the solar system. Based on a substantial database measured on Earth
+for representative planetary fluids at representative dynamic pressures up to
+200 GPa (2 Mbar) and a few 1000 K, the complex magnetic fields of U/N are (i)
+probably made primarily by degenerate metallic fluid H (MFH) at or near the
+crossover from the H-He envelopes to Ice cores at ~100 GPa (Mbar) pressures and
+normalized radii of ~90% of the radii of U/N; (ii) because those magnetic
+fields are made relatively close to the surfaces of U/N, non-dipolar fields can
+be expected; (iii) the Ice cores are most probably a heterogeneous fluid
+mixture of H, N, O, C, Fe/Ni and silicate-oxides and their mutual reaction
+products at high pressures and temperatures,as discussed elsewhere. Ironically,
+there is probably little nebular Ice in the Ice Giant Planets.",1503.01042v2
+2015-03-31,Magnetic Phase Diagram of the Breathing Pyrochlore Antiferromagnet LiGa1-xInxCr4O8,"The spinel oxides LiGaCr4O8 and LiInCr4O8 contain size-alternating pyrochlore
+lattices of spin-3/2 Cr3+ tetrahedra with different magnitudes of alternation.
+We show here that the solid solutions LiGa1-xInxCr4O8 between these two
+'breathing' pyrochlore compounds display (i) rapid suppression of magnetic and
+structural transitions upon doping the end members, (ii) spin-glass-like
+freezing above 2 K in the range 0.1 $\lesssim$ x $\lesssim$ 0.6, and (iii)
+apparent spin-gap behavior for x $\gtrsim$ 0.7. Furthermore, no transitions are
+observed above 2 K at x ~ 0.9, where magnetic susceptibility remains finite at
+2 K and magnetic heat capacity shows a quadratic temperature dependence at 1-5
+K. Our work shows that breathing pyrochlore compounds provide a unique
+opportunity for studying both geometrical frustration and bond alternation.",1503.08902v1
+2015-04-10,Variation of magnetic properties of Sr$_2$FeMoO$_6$ due to oxygen vacancies,"Oxygen vacancies can be of utmost importance for improving or deteriorating
+physical properties of oxide materials. Here, we studied from first-principles
+the electronic and magnetic properties of oxygen vacancies in the double
+perovskite Sr$_2$FeMoO$_6$ (SFMO). We show that oxygen vacancies can increase
+the Curie temperature in SFMO, although the total magnetic moment is reduced at
+the same time. We found also that the experimentally observed valence change of
+the Fe ions from $3+$ to $2+$ in the x-ray magnetic circular dichroism (XMCD)
+measurements is better explained by oxygen vacancies than by the assumed mixed
+valence state. The agreement of the calculated x-ray absorption spectra and
+XMCD results with experimental data is considerably improved by inclusion of
+oxygen vacancies.",1504.02629v6
+2015-05-04,Composite spin and quadrupole wave in the ordered phase of Tb$_{2+x}$Ti$_{2-x}$O$_{7+y}$,"The hidden ordered state of the frustrated pyrochlore oxide
+Tb$_{2+x}$Ti$_{2-x}$O$_{7+y}$ is possibly one of the two electric multipolar,
+or quadrupolar, states of the effective pseudospin-1/2 Hamiltonian derived from
+crystal-field ground state doublets of non-Kramers Tb$^{3+}$ ions. These
+long-range orders are antiparallel or parallel alignments of transverse
+pseudospin components representing electric quadrupole moments, which cannot be
+observed as magnetic Bragg reflections by neutron scattering. However
+pseudospin waves of these states are composite waves of the magnetic-dipole and
+electric-quadrupole moments, and can be partly observed by inelastic magnetic
+neutron scattering. We calculate these spin-quadrupole waves using linear
+spin-wave theory and discuss previously observed low-energy magnetic excitation
+spectra of a polycrystalline sample with $x = 0.005$ ($T_{\text{c}} = 0.5 $ K).",1505.00503v5
+2015-09-03,Spin-mediated dissipation and frequency shifts of a cantilever at milliKelvin temperatures,"We measure the dissipation and frequency shift of a magnetically coupled
+cantilever in the vicinity of a silicon chip, down to $25$ mK. The dissipation
+and frequency shift originates from the interaction with the unpaired
+electrons, associated with the dangling bonds in the native oxide layer of the
+silicon, which form a two dimensional system of electron spins. We approach the
+sample with a $3.43$ $\mu$m-diameter magnetic particle attached to an ultrasoft
+cantilever, and measure the frequency shift and quality factor as a function of
+temperature and the distance. Using a recent theoretical analysis [J. M. de
+Voogd et al., arXiv:1508.07972 (2015)] of the dynamics of a system consisting
+of a spin and a magnetic resonator, we are able to fit the data and extract the
+relaxation time $T_1=0.39\pm0.08$ ms and spin density $\sigma=0.14\pm0.01$
+spins per nm$^2$. Our analysis shows that at temperatures $\leq500$ mK magnetic
+dissipation is an important source of non-contact friction.",1509.01251v2
+2016-04-16,"Spin-orbit excitation energies, anisotropic exchange, and magnetic phases of honeycomb RuCl3","Using quantum chemistry calculations we shed fresh light on the electronic
+structure and magnetic properties of RuCl3, a proposed realization of the
+honeycomb Kitaev spin model. It is found that the nearest-neighbor Kitaev
+exchange K is weaker than in 5d5 Ir oxides but still larger than other
+effective spin couplings. The electronic-structure computations also indicate a
+ferromagnetic K in the halide, which is supported by a detailed analysis of the
+field-dependent magnetization. From exact-diagonalization calculations for
+extended Kitaev-Heisenberg Hamiltonians we additionally find that a transition
+from zigzag order to a spin-liquid ground state can be induced in RuCl3 with
+external magnetic field.",1604.04755v1
+2016-06-13,Electronic and magnetic structures and bonding properties of Ce2CrN3 and U2CrN3 from first principles,"The electronic and magnetic structures of A2CrN3 (A = Ce, U) ternary
+compounds calculated based on band magnetism within DFT exhibit different
+behaviors of the nf elements (n = 4, 5 resp.). Charge analysis allows to
+formally express the two compounds as A2Cr 5+ N3 5- thus classifying them as
+covalent nitrides, i.e. far from formal exchange of +- 9 electrons. From
+establishing the energy-volume equations of state, the two compounds are found
+with hardness magnitudes: B0(A=Ce) =192 GPa and B0(A=U) = 243 GPa, within range
+of oxides due to covalent metal-nitrogen bonding shown as based on overlap
+matrix analysis. The uranium compound is harder due to a smaller volume and
+less compressible U versus Ce metals. Ce2CrN3 exhibits large magnetization on
+Cr (1.94BM) and a very small moment develops on cerium (0.14 BM) pointing out
+to an intermediate valence state while in U2CrN3, M(Cr) = 0.49 BM and M(U) =
+0.97BM. These results are stressed by broad band-like density of states (DOS)
+behavior for A=U and localized DOS for A=Ce. Both compounds are found
+ferromagnetic in the ground state",1606.04066v1
+2017-03-29,Observation of Skyrmions at Room Temperature in Co2FeAl Heusler Alloy Ultrathin Films,"Magnetic skyrmions are topological spin structures having immense potential
+for energy efficient spintronic devices. However, observations of skyrmions at
+room temperature are limited to patterned nanostructures. Here, we report the
+observation of stable skyrmions in unpatterned Ta/Co2FeAl(CFA)/MgO thin film
+heterostructures at room temperature and in zero external magnetic field
+employing magnetic force microscopy. The skyrmions are observed in a trilayer
+structure comprised of heavy metal (HM)/ferromagnet (FM)/Oxide interfaces which
+result in strong interfacial Dzyaloshinskii-Moriya interaction (i-DMI) as
+evidenced by Brillouin light scattering measurements, in agreement with the
+results of micromagnetic simulations. We also emphasize on room temperature
+observation of multiple skyrmions which can be stabilized for suitable choices
+of CFA layer thickness, perpendicular magnetic anisotropy, and i-DMI. These
+results open up a new paradigm for designing room temperature spintronic
+devices based on skyrmions in FM continuous thin films.",1703.10224v1
+2017-08-09,Bubble Magnetometry of Nanoparticle Heterogeneity and Interaction,"Bubbles have a rich history as transducers in particle-physics experiments.
+In a solid-state analogue, we use bubble domains in nanomagnetic films to
+measure magnetic nanoparticles. This technique can determine the magnetic
+orientation of a single nanoparticle in a fraction of a second, and generate a
+full hysteresis loop in a few seconds, which is much faster than any other
+reported technique. We achieve this unprecedented speed by tuning the
+nanomagnetic properties of the films, including the Dzyaloshinskii-Moriya
+interaction, in the first application of topological protection from the
+skyrmion state to a nanoparticle sensor. We demonstrate the technique on
+iron/nickel nanorods and iron oxide nanoparticles, which delineate a wide range
+of properties and applications. Bubble magnetometry enables the first
+measurement with high throughput for statistical analysis of the magnetic
+hysteresis of dispersed nanoparticles, and the first direct measurement of a
+transition from superparamagnetic behavior as single nanoparticles to
+collective behavior in nanoscale agglomerates. These results demonstrate a
+breakthrough capability for measuring the heterogeneity and interaction of
+magnetic nanoparticles.",1708.02706v2
+2018-02-16,Carrier driven antiferromagnetism and exchange-bias in SrRuO3/CaRuO3 heterostructures,"Oxide heterostructures exhibit a rich variety of magnetic and transport
+properties which arise due to contact at an interface. This can lead to
+surprising effects that are very different from the bulk properties of the
+materials involved. We report the magnetic properties of bilayers of SrRuO3, a
+well known ferromagnet, and CaRuO3, which is nominally a paramagnet. We find
+intriguing features that are consistent with CaRuO3 developing dual magnetic
+character, with both a net moment as well as antiferromagnetic order. We argue
+the ordered SrRuO3 layer induces an undulating polarization profile in the
+conduction electrons of CaRuO3, by a mechanism akin to Friedel oscillations. At
+low temperatures, this oscillating polarization is inherited by rigid local
+moments within CaRuO3, leading to a robust exchange bias. We present ab initio
+simulations in support of this picture. Our results demonstrate a new ordering
+mechanism and throw light on the magnetic character of CaRuO3 .",1802.05869v1
+2018-04-25,Spin precession in anisotropic media,"We generalize the diffusive model for spin injection and detection in
+nonlocal spin structures to account for spin precession under an applied
+magnetic field in an anisotropic medium, for which the spin lifetime is not
+unique and depends on the spin orientation.We demonstrate that the spin
+precession (Hanle) line shape is strongly dependent on the degree of anisotropy
+and on the orientation of the magnetic field. In particular, we show that the
+anisotropy of the spin lifetime can be extracted from the measured spin signal,
+after dephasing in an oblique magnetic field, by using an analytical formula
+with a single fitting parameter. Alternatively, after identifying the
+fingerprints associated with the anisotropy, we propose a simple scaling of the
+Hanle line shapes at specific magnetic field orientations that results in a
+universal curve only in the isotropic case. The deviation from the universal
+curve can be used as a complementary means of quantifying the anisotropy by
+direct comparison with the solution of our generalized model. Finally, we
+applied our model to graphene devices and find that the spin relaxation for
+graphene on silicon oxide is isotropic within our experimental resolution.",1804.09426v1
+2010-05-19,2D orbital-like magnetic order in ${\rm La_{2-x}Sr_xCuO_4}$,"In high temperature copper oxides superconductors, a novel magnetic order
+associated with the pseudogap phase has been identified in two different
+cuprate families over a wide region of temperature and doping. We here report
+the observation below 120 K of a similar magnetic ordering in the archetypal
+cuprate ${\rm La_{2-x}Sr_xCuO_4}$ (LSCO) system for x=0.085. In contrast to the
+previous reports, the magnetic ordering in LSCO is {\it\bf only} short range
+with an in-plane correlation length of $\sim$ 10 \AA\ and is bidimensional
+(2D). Such a less pronounced order suggests an interaction with other
+electronic instabilities. In particular, LSCO also exhibits a strong tendency
+towards stripes ordering at the expense of the superconducting state.",1005.3406v1
+2013-08-05,Spin and Orbital Contributions to Magnetically Ordered Moments in 5d Layered Perovskite Sr2IrO4,"The ratio of orbital (L) and spin (S) contributions to the magnetically
+ordered moments of a 5d transition metal oxide, Sr2IrO4 was evaluated by
+non-resonant magnetic x-ray diffraction. We applied a new experimental setting
+to minimize the error in which we varied only the linear-polarization of
+incident x-ray at a fixed scattering angle. Strong polarization dependence of
+the intensity of magnetic diffraction was observed, from which we conclude that
+the ordered moments contain substantial contribution from the orbital degree of
+freedom with the ratio of <L>/<S> ~5.0, evidencing the pronounce effect of
+spin-orbit coupling. The obtained ratio is close to but slightly larger than
+the expected value for the ideal J_eff = 1/2 moment of a spin-orbital Mott
+insulator, |<J_1/2|L_z|J_1/2>|/|<J_1/2|S_z|J_1/2>| = 4, which cannot be
+accounted by the redistribution of orbital components within the t_2g bands
+associated with the elongation of the IrO6 octahedra.",1308.0923v1
+2013-08-15,Magnetic Phase Diagram of a Five-Orbital Hubbard Model in the Real-Space Hartree Fock Approximation Varying the Electronic Density,"Using the real-space Hartree Fock approximation, the magnetic phase diagram
+of a five-orbital Hubbard model for the iron-based superconductors is studied
+varying the electronic density $n$ in the range from 5 to 7 electrons per
+transition metal atom. The Hubbard interaction $U$ is also varied, at a fixed
+Hund coupling $J/U=0.25$. Several qualitative trends and a variety of competing
+magnetic states are observed. At $n$=5, a robust G-type antiferromagnetic
+insulator is found, in agreement with experimental results for BaMn$_2$As$_2$.
+As $n$ increases away from 5, magnetic states with an increasing number of
+nearest-neighbors ferromagnetic links become energetically stable. This
+includes the well-known C-type antiferromagnetic state at $n$=6, the E-phase
+known to exist in FeTe, and also a variety of novel states not found yet
+experimentally, some of them involving blocks of ferromagnetically oriented
+spins. Regions of phase separation, as in Mn-oxides, have also been detected.
+Comparison with previous theoretical investigations indicate that these
+qualitative trends may be generic characteristics of phase diagrams of
+multiorbital Hubbard models.",1308.3426v1
+2014-03-19,Nature of Structural Changes Near the Magnetic Ordering Temperature in Small-Ion Rare Earth Perovskites RMnO3,"Detailed structural measurements were conducted on a new perovskite, ScMnO3,
+and on orthorhombic LuMnO3. Complementary density functional theory (DFT)
+calculations were carried out, and predict that ScMnO3 possesses E-phase
+magnetic order at low temperature with displacements of the Mn sites (relative
+to the high temperature state) of ~0.07 {\AA}, compared to ~ 0.04 {\AA}
+predicted for LuMnO3. However, detailed local, intermediate and long-range
+structural measurements by x-ray pair distribution function analysis, single
+crystal x-ray diffraction and x-ray absorption spectroscopy, find no local or
+long- range distortions on crossing into the low temperature E-phase of the
+magnetically ordered state. The measurements place upper limits on any
+structural changes to be at most one order of magnitude lower than density
+functional theory predictions and suggest that this theoretical approach does
+not properly account for the spin-lattice coupling in these oxides and may
+possibly predict the incorrect magnetic order at low temperatures. The results
+suggest that the electronic contribution to the electrical polarization
+dominates and should be properly treated in theoretical models.",1403.4807v1
+2016-11-08,Thermal and Magnetic Properties of Nanostructured Ferrimagnetic Composites with Graphene - Graphite Fillers,"We report the results of an experimental study of thermal and magnetic
+properties of nanostructured ferrimagnetic iron oxide composites with graphene
+and graphite fillers synthesized via the current activated pressure assisted
+densification. The thermal conductivity was measured using the laser-flash and
+transient plane source techniques. It was demonstrated that addition of 5 wt. %
+of equal mixture of graphene and graphite flakes to the composite results in a
+factor of x2.6 enhancement of the thermal conductivity without significant
+degradation of the saturation magnetization. The microscopy and spectroscopic
+characterization reveal that sp2 carbon fillers preserve their crystal
+structure and morphology during the composite processing. The strong increase
+in the thermal conductivity was attributed to the excellent phonon heat
+conduction properties of graphene and graphite. The results are important for
+energy and electronic applications of the nanostructured permanent magnets.",1611.02359v1
+2017-01-09,Absence of magnetic long range order in Ba$_3$ZnRu$_2$O$_9$: A spin-liquid candidate in the $S=3/2$ dimer lattice,"We have discovered a novel candidate for a spin liquid state in a ruthenium
+oxide composed of dimers of $S = $ 3/2 spins of Ru$^{5+}$,Ba$_3$ZnRu$_2$O$_9$.
+This compound lacks a long range order down to 37 mK, which is a temperature
+5000-times lower than the magnetic interaction scale of around 200 K. Partial
+substitution for Zn can continuously vary the magnetic ground state from an
+antiferromagnetic order to a spin-gapped state through the liquid state. This
+indicates that the spin-liquid state emerges from a delicate balance of inter-
+and intra-dimer interactions, and the spin state of the dimer plays a vital
+role. This unique feature should realize a new type of quantum magnetism.",1701.02257v2
+2017-01-14,Strong perpendicular magnetic anisotropy energy density at Fe alloy/HfO2 interfaces,"We report on the perpendicular magnetic anisotropy (PMA) behavior of heavy
+metal (HM)/ Fe alloy/MgO thin film heterostructures after an ultrathin HfO2
+passivation layer is inserted between the Fe alloy and the MgO. This is
+accomplished by depositing one to two atomic layers of Hf onto the Fe alloy
+before the subsequent rf sputter deposition of the MgO layer. This Hf layer is
+fully oxidized during the subsequent deposition of the MgO layer, as confirmed
+by X-ray photoelectron spectroscopy measurements. As the result a strong
+interfacial perpendicular anisotropy energy density can be achieved without any
+post-fabrication annealing treatment, for example 1.7 erg/cm^2 for the
+Ta/Fe60Co20B20/HfO2/MgO heterostructure. Depending on the HM, further
+enhancements of the PMA can be realized by thermal annealing to at least 400C.
+We show that ultra-thin HfO2 layers offer a range of options for enhancing the
+magnetic properties of magnetic heterostructures for spintronics applications.",1701.03933v1
+2017-01-24,Spin mediated enhanced negative magnetoresistance in Ni80Fe20 and p-silicon bilayer,"In this work, we present an experimental study of spin mediated enhanced
+negative magnetoresistance in Ni80Fe20 (50 nm)/p-Si (350 nm) bilayer. The
+resistance measurement shows a reduction of ~2.5% for the bilayer specimen as
+compared to 1.3% for Ni80Fe20 (50 nm) on oxide specimen for an out-of-plane
+applied magnetic field of 3T. In the Ni80Fe20-only film, the negative
+magnetoresistance behavior is attributed to anisotropic magnetoresistance. We
+propose that spin polarization due to spin-Hall effect is the underlying cause
+of the enhanced negative magnetoresistance observed in the bilayer. Silicon has
+weak spin orbit coupling so spin Hall magnetoresistance measurement is not
+feasible. We use V2{\omega} and V3{\omega} measurement as a function of
+magnetic field and angular rotation of magnetic field in direction normal to
+electric current to elucidate the spin-Hall effect. The angular rotation of
+magnetic field shows a sinusoidal behavior for both V2{\omega} and V3{\omega},
+which is attributed to the spin phonon interactions resulting from the
+spin-Hall effect mediated spin polarization. We propose that the spin
+polarization leads to a decrease in hole-phonon scattering resulting in
+enhanced negative magnetoresistance.",1701.07049v1
+2012-04-10,Observation of spin-glass behavior in nickel adsorbed few layer graphene,"Nickel-adsorbed graphene was prepared by first synthesizing graphite oxide
+(GO) by modified Hummers' method and then reducing a solution containing both
+GO and $Ni^{2+}$. EDX analysis showed 31 atomic percent nickel was present.
+Magnetization measurements under both dc and ac magnetic fields were carried
+out in the temperature range 2 K to 300 K. The zero field cooled and field
+cooled magnetization data showed a pronounced irreversibility at a temperature
+around 20 K. The analysis of the ac susceptibility data were carried out by
+both Vogel-Fulcher as well as power law. From dynamic scaling analysis the
+microscopic flipping time $\tau_{0}\sim 10^{-13} s$ and critical exponent
+$z\nu=5.9\pm0.1$ were found, indicating presence of conventional spin glass in
+the system. The spin glass transition temperature was estimated as 19.5 K.
+  Decay of thermoremanent magnetization (TRM) was explained by stretched
+exponential function with a value of the exponent as 0.6 .
+  From the results it is concluded that nickel adsorbed graphene behaves like a
+spin-glass.",1204.2123v2
+2012-04-27,"Disorder, cluster spin glass, and hour-glass spectra in striped magnetic insulators","Hour-glass-shaped magnetic excitation spectra have been detected in a variety
+of doped transition-metal oxides with stripe-like charge order. Compared to the
+predictions of spin-wave theory, these spectra display a different intensity
+distribution and anomalous broadening. Here we show, based on a comprehensive
+modelling of these phenomena for La5/3Sr1/3CoO4, how quenched disorder in the
+charge sector causes frustration, and consequently cluster-glass behavior at
+low temperatures, in the spin sector. This spin-glass physics, which is
+insensitive to the detailed nature of the charge disorder, but sensitive to the
+relative strength of the magnetic inter-stripe coupling, ultimately determines
+the distribution of magnetic spectral weight and thus causes the hour-glass
+spectrum.",1204.6323v2
+2016-08-10,Effect of rare-earth (Er and Gd) substitution on the magnetic and multiferroic properties of DyFe0.5Cr0.5O3,"We report the results of our investigations on the influence of partial
+substitution of Er and Gd for Dy on the magnetic and magnetoelectric properties
+of DyFe0.5Cr0.5O3, which is known to be a multiferroic system. Magnetic
+susceptibility and heat capacity data, apart from confirming the occurrence of
+magnetic transitions at ~ 121 and 13 K in DyFe0.5Cr0.5O3, bring out that the
+lower transition temperature only is suppressed by rare-earth substitution.
+Multiferroic behavior is found to persist in Dy0.4Ln0.6Fe0.5Cr0.5O3 (Ln= Er and
+Gd). There is an evidence for magnetoelectric coupling in all these materials
+with qualitative differences in its behavior as the temperature is changed
+across these two transitions. Remnant electric polarization is observed for all
+the compounds. The most notable observation is that electric polarization is
+seen to get enhanced as a result of rare-earth substitution with respect to
+that in DyFe0.5Cr0.5O3. Interestingly, similar trend is seen in magnetocaloric
+effect, consistent with the existence of magnetoelectric coupling. The results
+thus provide evidence for the tuning of magnetoelectric coupling by rare-earth
+substitution in this family of oxides.",1608.03228v1
+2018-09-19,Incorporation of magnetic nanoparticles into lamellar polystyrene-b-poly(n-butyl methacrylate) diblock copolymer films: influence of the chain end-groups on nanostructuration,"In this article, we present new samples of lamellar magnetic nanocomposites
+based on the self-assembly of a polystyrene-b-poly(n-butyl methacrylate)
+diblock copolymer synthesized by atom transfer radical polymerization. The
+polymer films were loaded with magnetic iron oxide nanoparticles covered with
+polystyrene chains grown by surface initiated-ATRP. The nanostructuration of
+the pure and magnetically loaded copolymer films on silicon was studied by
+atomic force microscopy, ellipsometry, neutron reflectivity and contact angle
+measurement. The present study highlights the strong influence of the copolymer
+extremity - driven itself by the choice of the ATRP chemical route - on the
+order of the repetition sequences of the blocks in the multi-lamellar films. In
+addition, a narrower distribution of the nanoparticles' sizes was examined as a
+control parameter of the SI-ATRP reaction.",1809.07063v1
+2018-09-27,"$\mathrm{Fe}_{1-x}\mathrm{Ni}_x$ Alloy Nanoparticles Encapsulated inside Carbon Nanotubes: Controlled Synthesis, Structure and Magnetic Properties","In the present work, different synthesis procedures have been demonstrated to
+fill carbon nanotubes (CNTs) with $\mathrm{Fe}_{1-x}\mathrm{Ni}_x$ alloy
+nanoparticles (x = 0.33, 0.5). CNTs act as templates for the encapsulation of
+magnetic nanoparticles, and provide a protective shield against oxidation as
+well as prevent nanoparticles agglomeration. By variation of the reaction
+parameters, the purity of the samples, degree of filling, the composition and
+size of filling nanoparticles have been tailored and therefore the magnetic
+properties. The samples were analyzed by scanning electron microscopy (SEM),
+transmission electron microscopy (TEM), Bright-field (BF) TEM tomography, X-ray
+powder diffraction, superconducting quantum interference device (SQUID) and
+thermogravimetric analysis (TGA). The Fe1-xNix-filled CNTs show a huge
+enhancement in the coercive fields compared to the corresponding bulk
+materials, which make them excellent candidates for several applications such
+as magnetic storage devices.",1809.10500v1
+2018-09-28,Defect-induced exchange bias in a single SrRuO3 layer,"Exchange bias stems from the interaction between different magnetic phases
+and therefore it generally occurs in magnetic multilayers. Here we present a
+large exchange bias in a single SrRuO3 layer induced by helium ion irradiation.
+When the fluence increases, the induced defects not only suppress the
+magnetization and the Curie temperature, but also drive a metal-insulator
+transition at a low temperature. In particular, a large exchange bias field up
+to around 0.36 T can be created by the irradiation. This large exchange bias is
+related to the coexistence of different magnetic and structural phases that are
+introduced by embedded defects. Our work demonstrates that spintronic
+properties in complex oxides can be created and enhanced by applying ion
+irradiation.",1809.11035v1
+2019-09-05,Large off diagonal exchange couplings and spin liquid states in $\mathbf{C_3}$ symmetric iridates,"Iridate oxides on a honeycomb lattice are considered promising candidates for
+realization of quantum spin liquid states. We investigate the magnetic
+couplings in a structural model for a honeycomb iridate K$_2$IrO$_3$, with
+$C_3$ point group symmetry at the Ir sites, which is an end member of the
+recently synthesized iridate family K$_x$Ir$_y$O$_2$. Using \textit{ab-initio}
+quantum chemical methods, we elucidate the subtle relationship between the real
+space symmetry and magnetic anisotropy and show that the higher point group
+symmetry leads to high frustration with strong magnetic anisotropy driven by
+the unusually large off-diagonal exchange couplings ($\Gamma$'s) as opposed to
+other spin-liquid candidates considered so far. Consequently, large quantum
+fluctuations imply lack of magnetic ordering consistent with the experiments.
+Exact diagonalization calculations for the fully anisotropic $K$-$J$-$\Gamma$
+Hamiltonian reveal the importance of the off-diagonal anisotropic exchange
+couplings in stabilizing a spin liquid state and highlight an alternative route
+to stabilize spin liquid states for ferromagnetic $K$.",1909.02277v1
+2017-11-28,Interplay of spin-orbit coupling and hybridization in Ca3LiOsO6 and Ca3LiRuO6,"The electronic ground state of Ca3LiOsO6 was recently considered within an
+intermediate coupling regime that revealed J=3/2 spin-orbit entangled magnetic
+moments. Through inelastic neutron scattering and density functional theory we
+investigate the magnetic interactions and probe how the magnetism is influenced
+by the change in hierarchy of interactions as we move from Ca3LiOsO6 (5d3) to
+Ca3LiRuO6 (4d3). An alteration of the spin-gap and ordered local moment is
+observed, however the magnetic structure, Neel temperature and exchange
+interactions are unaltered. To explain this behavior it is necessary to include
+both spin-orbit coupling and hybridization, indicating the importance of an
+intermediate coupling approach when describing 5$d$ oxides.",1711.10393v1
+2018-06-18,Impurity-induced vector spin chirality and anomalous Hall effect in ferromagnetic metals,"Scattering by multiple scatterers sometimes gives rise to nontrivial
+consequences such as anomalous Hall effect. We here study a mechanism for
+anomalous Hall effect which originates from the correlation of nonmagnetic
+impurities and localized moments; a Hall effect induced by vector spin
+chirality. Using a scattering theory approach, we study the skew scattering
+induced by the scattering processes that involve two magnetic moments and a
+non-magnetic impurity, which is proportional to the vector spin chirality of
+the spins in the vicinity of the non-magnetic impurity. Furthermore, we show
+that a finite vector spin chirality naturally exists around an impurity in the
+usual ferromagnetic metals at finite temperature due to the local
+inversion-symmetry breaking by the impurity. The result is potentially relevant
+to magnetic oxides which the anomalous Hall effect is enhanced at finite
+temperatures.",1806.06833v1
+2018-06-25,Ferromagnetism above 1000 K in highly cation-ordered double-perovskite insulator Sr3OsO6,"Magnetic insulators have been intensively studied for over 100 years, and
+they, in particular ferrites, are considered to be the cradle of magnetic
+exchange interactions in solids. Their wide range of applications include
+microwave devices and permanent magnets . They are also suitable for spintronic
+devices owing to their high resistivity, low magnetic damping, and
+spin-dependent tunneling probabilities. The Curie temperature is the crucial
+factor determining the temperature range in which any ferri/ferromagnetic
+system remains stable. However, the record Curie temperature has stood for over
+eight decades in insulators and oxides (943 K for spinel ferrite LiFe5O8). Here
+we show that a highly B-site ordered double-perovskite, Sr2(SrOs)O6 (Sr3OsO6),
+surpasses this long standing Curie temperature record by more than 100 K. We
+revealed this B-site ordering by atomic-resolution scanning transmission
+electron microscopy. The density functional theory (DFT) calculations suggest
+that the large spin-orbit coupling (SOC) of Os6+ 5d2 orbitals drives the system
+toward a Jeff = 3/2 ferromagnetic (FM) insulating state. Moreover, the Sr3OsO6
+is the first epitaxially grown osmate, which means it is highly compatible with
+device fabrication processes and thus promising for spintronic applications.",1806.09308v1
+2018-08-11,Role of Ce 4f hybridization in the origin of magnetism in nanoceria,"Nanoscale CeO2 (nanoceria) is a prototypical system that presents d0
+ferromagnetism. Using a combination of x-ray absorption spectroscopy, x-ray
+magnetic circular dichroism and modelling, we show that nanostructure, defects
+and disorder, and non-stoichiometry create magnetically polarized Ce 4f and O
+2p hybridized states captured by the vacancy orbitals (Vorb) that are vital to
+ferromagnetism. Further, we demonstrate that foreign ions (Fe and Co) enhance
+the moment at Ce 4f sites while the number of Vorb is unchanged, pointing
+clearly to the mechanism of orbital hybridization being key missing ingredient
+to understanding the unexpected ferromagnetism in many nanoscale dilute
+magnetic oxides and semiconductors.",1808.03758v3
+2019-01-30,Tuning the Magnetic Ordering Temperature of Hexagonal Ferrites by Structural Distortion Control,"To tune the magnetic properties of hexagonal ferrites, a family of
+magnetoelectric multiferroic materials, by atomic-scale structural engineering,
+we studied the effect of structural distortion on the magnetic ordering
+temperature (TN). Using the symmetry analysis, we show that unlike most
+antiferromagnetic rare-earth transition-metal perovskites, a larger structural
+distortion leads to a higher TN in hexagonal ferrites and manganites, because
+the K3 structural distortion induces the three-dimensional magnetic ordering,
+which is forbidden in the undistorted structure by symmetry. We also revealed a
+near-linear relation between TN and the tolerance factor and a power-law
+relation between TN and the K3 distortion amplitude. Following the analysis, a
+record-high TN (185 K) among hexagonal ferrites was predicted in hexagonal
+ScFeO3 and experimentally verified in epitaxially stabilized films. These
+results add to the paradigm of spin-lattice coupling in antiferromagnetic
+oxides and suggests further tunability of hexagonal ferrites if more lattice
+distortion can be achieved.",1901.11118v1
+2019-02-12,Magnetically driven loss of centrosymmetry in metallic Pb2CoOsO6,"We report magnetic, transport, neutron diffraction, and muon spin rotation
+data showing that Pb$_2$CoOsO$_6$, a newly synthesized metallic
+double-perovskite with a centrosymmetric space group at room temperature,
+exhibits a continuous second-order phase transition at 45 K to a magnetically
+ordered state with a non-centrosymmetric space group. The absence of inversion
+symmetry is very uncommon in metals, particularly metallic oxides. In contrast
+to the recently reported ferroelectric-like structural transition in LiOsO$_3$,
+the phase transition in Pb$_2$CoOsO$_6$ is driven by a long-range collinear
+antiferromagnetic order, with propagation vector $\textbf{k} =
+(\frac{1}{2},0,\frac{1}{2})$, which relieves the frustration associated with
+the symmetry of themagnetic exchanges. This magnetically-driven loss of
+inversion symmetry represents a new frontier in the search for novel metallic
+behavior.",1902.04482v2
+2019-02-20,Electron states and magnetic phase diagrams of strongly correlated systems,"Various auxiliary-particle approaches to treat electron correlations in
+many-electron models are analyzed. Applications to copper-oxide layered systems
+are discussed. The ground-state magnetic phase diagrams are considered within
+the Hubbard and $s$-$d$ exchange (Kondo) models for square and simple cubic
+lattices vs. band filling and interaction parameter. A generalized Hartree-Fock
+approximation is employed to treat commensurate ferro-, antiferromagnetic, and
+incommensurate (spiral) magnetic phases, and also magnetic phase separation.
+The correlations are taken into account within the Hubbard model by using the
+slave-boson approach. The main advantage of this approach is correct estimating
+the contribution of doubly occupied states number and therefore the
+paramagnetic phase energy.",1902.07431v1
+2019-03-12,Superconductivity behavior in epitaxial TiN films points at surface magnetic disorder,"We analyze the evolution of the normal and superconducting electronic
+properties in epitaxial TiN films, characterized by high Ioffe-Regel parameter
+values, as a function of the film thickness. As the film thickness decreases,
+we observe an increase of in the residual resistivity, which becomes dominated
+by diffusive surface scattering for $d\leq20\,$nm. At the same time, a
+substantial thickness-dependent reduction of the superconducting critical
+temperature is observed compared to the bulk TiN value. In such a high quality
+material films, this effect can be explained by a weak magnetic disorder
+residing in the surface layer with a characteristic magnetic defect density of
+$\sim10^{12}\,\mathrm{cm}^{-2}$. Our results suggest that surface magnetic
+disorder is generally present in oxidized TiN films.",1903.05009v3
+2019-04-08,"YBa2Cu3O7/LaXMnO3 (X: Ca, Sr) based Superconductor/Ferromagnet/Superconductor junctions with memory functionality","Complex oxides exhibit a variety of unusual physical properties, which can be
+used for designing novel electronic devices. Here we fabricate and study
+experimentally nano-scale Superconductor/ Ferromagnet/Superconductor junctions
+with the high-Tc cuprate superconductor YBa2Cu3O7 and the colossal
+magnetoresistive (CMR) manganite ferromagnets LaXMnO3 (X: Ca or Sr). We
+demonstrate that in a broad temperature range the magnetization of a manganite
+nanoparticle, forming the junction interface, switches abruptly in a
+mono-domain manner. The CMR phenomenon translates the magnetization loop into a
+hysteretic magnetoresistance loop. The latter facilitates a memory
+functionality of such a junction with just a single CMR ferromagnetic layer.
+The orientation of the magnetization (stored information) can be read out by
+simply measuring the junction resistance in an applied magnetic field. The CMR
+facilitates a large read-out signal in a small applied field. We argue that
+such a simple single layer CMR junction can operate as a memory cell both in
+the superconducting state at cryogenic temperatures and in the normal state up
+to room temperature.",1904.03951v1
+2020-09-30,Electronic structure and finite temperature magnetism of yttrium iron garnet,"Yttrium iron garnet is a complex ferrimagnetic insulator with 20 magnon modes
+which is used extensively in fundamental experimental studies of magnetisation
+dynamics. As a transition metal oxide with moderate gap (2.8 eV), yttrium iron
+garnet requires a careful treatment of electronic correlation. We have applied
+quasiparticle self-consistent GW to provide a fully ab initio description of
+the electronic structure and resulting magnetic properties, including the
+parameterisation of a Heisenberg model for magnetic exchange interactions.
+Subsequent spin dynamical modelling with quantum statistics extends our
+description to the magnon spectrum and thermodynamic properties such as the
+Curie temperature, finding favourable agreement with experimental measurements.
+This work provides a snapshot of the state-of-the art in modelling of complex
+magnetic insulators.",2009.14601v1
+2020-11-27,d0 Ferromagnetism in Mg-doped Rutile TiO2 Nanoparticles,"In a quest of enriching the area of d0 magnetism in oxide materials, we have
+undertaken to study Mg-doped TiO2 compounds. The Ti1-xMgxO2 (x=0, 0.02, 0.04
+and 0.06) nanoparticles were prepared by solid-state reaction route. The X-ray
+diffractions (XRD) patterns of these samples indicate single phase of
+tetragonal rutile-structure of TiO2. The refinement of the XRD patterns reveals
+no change in the crystallographic lattice parameters in comparison to pure TiO2
+upon Mg doping and it indicates that Mg2+ ions do not enter core grains and
+form core/shell structure. SEM observations reveal the uniform morphology with
+nanometric grains in the range of 150-200 nm. The measurement of magnetic
+properties of these compounds indicates that pure TiO2 and Ti0.98Mg0.02
+compounds exhibit paramagnetic behavior and Ti0.96Mg0.04 compound exhibits
+ferromagnetic (FM) phase superimposed with the dominating paramagnetic phase.
+However, Ti0.94Mg0.06 compound exhibits ferromagnetic to paramagnetic
+transition with FM transition temperature of 180.2 K. The measurements of zero
+field and field cooled magnetization data indicate low temperature magnetic
+irreversibility for x=0.06 sample and it was attributed to the competing AFM
+(core) and the FM (shell) interactions. The measurement of hysteresis curves at
+various temperatures indicates domain wall pinning and an exchange-bias
+behavior.",2011.13718v1
+2021-03-20,Importance of anisotropic Coulomb interactions in the electronic and magnetic properties of Mn$_3$O$_4$,"We report the importance of anisotropic Coulomb interactions in DFT+U
+calculations of the electronic and magnetic properties of Mn$_3$O$_4$. The
+effects of anisotropic interactions in Mn$^{2+}$ and Mn$^{3+}$ are separately
+examined by defining two different sets of Hubbard parameters: $U^{2+}$ and
+$J^{2+}$ for Mn$^{2+}$ and $U^{3+}$ and $J^{3+}$ for Mn$^{3+}$. The anisotropic
+interactions in Mn$^{3+}$ have a significant impact on the physical properties
+of Mn$_3$O$_4$ including local magnetic moments, canted angle, spontaneous
+magnetic moment, and superexchange coupling, but those in Mn$^{2+}$ do not make
+any noticeable difference. Weak ferromagnetic interchain superexchange,
+observed in experiments, is predicted only if a sizable anisotropic interaction
+is considered in Mn$^{3+}$. By analyzing the eigenoccupations of the on-site Mn
+density matrix, we found that the spin channel involving Mn$^{3+}$
+$d_{x^2-y^2}$ orbitals, which governs the 90$^\circ$ correlation superexchange,
+is directly controlled by the anisotropic interactions. These findings
+demostrate that the exchange correction $J$ for the intraorbital Coulomb
+potential is of critical importance for first-principles description of reduced
+Mn oxides containing Mn$^{3+}$ or Mn$^{4+}$.",2103.11082v1
+2021-04-16,Electronic and magnetic properties of VOCl/FeOCl antiferromagnetic heterobilayers,"We study the electronic properties of the heterobilayer of vanadium and iron
+oxychlorides, VOCl and FeOCl, two layered air stable van der Waals insulating
+oxides with different types of antiferromagnetic order in bulk: VOCl monolayers
+are ferromagnetic (FM) whereas the FeOCl monolayers are antiferromagnetic (AF).
+We use density functional theory (DFT) calculations, with Hubbard correction
+that is found to be needed to describe correctly the insulating nature of these
+compounds. We compute the magnetic anisotropy and propose a spin model
+Hamiltonian. Our calculations show that interlayer coupling in weak and
+ferromagnetic so that magnetic order of the monolayers is preserved in the
+heterobilayers providing thereby a van der Waals heterostructure that combines
+two monolayers with different magnetic order. Interlayer exchange should lead
+both to exchange bias and to the emergence of hybrid collective modes that that
+combine FM and AF magnons. The energy band of the heterobilayer show a type II
+band alignment, and feature spin-splitting of the states of the AF layer due to
+the breaking of the inversion symmetry.",2104.08214v1
+2021-05-28,Exceptional sign changes of the non-local spin Seebeck effect in antiferromagnetic hematite,"Low power spintronic devices based on the propagation of pure magnonic spin
+currents in antiferromagnetic insulator materials offer several distinct
+advantages over ferromagnetic components including higher frequency magnons and
+a stability against disturbing external magnetic fields. In this work, we make
+use of the insulating antiferromagnetic phase of iron oxide, the mineral
+hematite $\alpha$-Fe$_2$O$_3$ to investigate the long distance transport of
+thermally generated magnonic spin currents. We report on the excitation of
+magnons generated by the spin Seebeck effect, transported both parallel and
+perpendicular to the antiferromagnetic easy-axis under an applied magnetic
+field. Making use of an atomistic hematite toy model, we calculate the
+transport characteristics from the deviation of the antiferromagnetic ordering
+from equilibrium under an applied field. We resolve the role of the magnetic
+order parameters in the transport, and experimentally we find significant
+thermal spin transport without the need for a net magnetization.",2105.13653v1
+2021-07-13,Exploration of trivial and non-trivial electronic phases and of collinear and non-collinear magnetic phases in low-spin d$^5$ perovskites,"The $4d$ and $5d$ transition metal oxides have become important members of
+the emerging quantum materials family due to competition between onsite Coulomb
+repulsion ($U$) and spin-orbit coupling (SOC). Specifically, the systems with
+$d^5$ electronic configuration in an octahedral environment are found to be
+capable of posessing invariant semimetallic state and perturbations can lead to
+diverse magnetic phases. In this work, by formulating a multi-band Hubbard
+model and performing SOC tunable DFT+$U$ calculations on a prototype SrIrO$_3$
+and extending the analysis to other iso-structural and isovalent compounds, we
+present eight possible electronic and magnetic configurations in the $U$-SOC
+phase diagram that can be observed in the family of low-spin $d^5$ perovskites.
+They include the protected Dirac semimetal state, metal and insulator regimes,
+collinear and noncollinear spin ordering. The latter is explained through
+connecting hopping interactions to the rotation and tilting of the octahedra as
+observed in GdFeO$_3$. Presence of several soft phase boundaries makes the
+family of $d^5$ perovskites an ideal platform to study electronic and magnetic
+phase transitions under external stimuli.",2107.06016v2
+2021-10-21,Micromagnetic simulations of clusters of nanoparticles with internal structure: Application to magnetic hyperthermia,"Micromagnetic simulation results on dynamic hysteresis loops of clusters of
+iron oxide nanoparticles (NPs) with internal structure composed of nanorods are
+compared with the widely used macrospin approximation. Such calculations
+allowing for nanorod-composed NPs is facilitated by a previously developed
+coarse-graining method based on the renormalization group approach. With a
+focus on applications to magnetic hyperthermia, we show that magnetostatic
+interactions improve the heating performance of NPs in chains and triangles,
+and reduce heating performance in fcc arrangements. Hysteresis loops of
+triangular and fcc systems of complex NPs are not recovered within the
+macrospin approximation, especially at smaller interparticle distances. For
+triangular arrangements, the macrospin approximation predicts that
+magnetostatic interactions reduce loop area, in contrast to the complex NP
+case. An investigation of the local hysteresis loops of individual NPs and
+macrospins in clusters reveals the impact of the geometry of their neighbours
+on individual versus collective magnetic response, inhomogenous heating within
+clusters, and further differences between simulating NPs with internal
+structure and the use of the macrospin approximation. Capturing the internal
+physical and magnetic structure of NPs is thus important for some applications.",2110.11178v2
+2022-01-27,Edge and Width Dependent Electronic Properties of Nanoribbons of Manganese Oxide,"In the present work, the structural, magnetic, and electronic properties of
+the two- and one-dimensional honeycomb structures of recently synthesized MnO
+[Zhang et al. Nat. Commun., 20, 1073-1078 (2021)] are investigated by using
+first principles calculations. Our calculations show that the single layer 2D
+MnO crystal has a degenerate antiferromagnetic (AFM) ground state and a
+relatively less favorable ferromagnetic (FM) state. In addition, magnetic
+anisotropy calculations unveil that the easy-axis direction for magnetism
+originating from unpaired electron states in manganese atoms is normal to the
+crystal plane. Electronically, while the FM-MnO is a direct semiconductor with
+a narrow bandgap, AFM phases display large indirect bandgap semiconducting
+behavior. Moreover, calculations on nanoribbons of MnO reveal that zigzag edged
+ribbons display metallic bahavior, whereas armchair edged nanoribbons are
+semiconductors. Magnetically, for both zigzag- or armchair-edged nanoribbons,
+AFM order perpendicular to the nanoribbon growth direction is found to be
+favorable over the other AFM and FM orders. Moreover, depending on the edge
+symmetry and ribbon width, forbidden band gap values of nanoribbons display
+distinct family behaviors.",2201.11698v1
+2022-08-11,"A versatile platform for graphene nanoribbon synthesis, electronic decoupling, and spin polarized measurements","The on-surface synthesis of nano-graphenes has led the charge in prototyping
+structures with perspectives beyond silicon-based technology. Following reports
+of open-shell systems in graphene-nanoribbons (GNR), a flurry of research
+activities is directed at investigating their magnetic properties with a keen
+eye for spintronic applications. Although the synthesis of nano-graphenes is
+usually straightforward on gold, it is difficult to use it for electronic
+decoupling and spin-polarized measurements. Using a binary alloy Cu3Au(111), we
+show how to combine the efficient gold-like nano-graphene formation with spin
+polarization and electronic decoupling known from copper. We prepare copper
+oxide layers, demonstrate thermally and tip-assisted synthesis of GNR and grow
+thermally stable magnetic Co islands. We functionalize the tip of a scanning
+tunneling microscope with carbon-monoxide, nickelocene, or attach Co clusters
+for high-resolution imaging, magnetic sensing, or spin-polarized measurements.
+This versatile platform will be a valuable tool in the advanced study of
+magnetic nano-graphenes.",2208.05760v1
+2022-09-22,Spin wave study of magnetic perpendicular surface anisotropy in single crystalline MgO$\text{/}$Fe$\text{/}$MgO films,"Broadband ferromagnetic resonance is measured in single crystalline Fe films
+of varying thickness sandwiched between MgO layers. An exhaustive magnetic
+characterization of the films (exchange constant, cubic, uniaxial and surface
+anisotropies) is enabled by the study of the uniform and the first
+perpendicular standing spin wave modes as a function of applied magnetic field
+and film thickness. Additional measurements of non-reciprocal spin wave
+propagation allow us to separate each of the two interface contributions to the
+total surface anisotropy. The results are consistent with the model of a
+quasi-bulk film interior and two magnetically different top and bottom
+interfaces, a difference ascribed to different oxidation states.",2209.10906v2
+2022-12-01,Weyl Metal Phase in Delafossite Oxide PtNiO$_2$,"On the basis of density functional theory calculations we predict Weyl points
+in rhombohedral structure of PtNiO$_2$ having symmorphic symmetry. From the
+formation energy and phonon calculations, PtNiO$_2$ is found to be structurally
+stable. The magnetic ground state is ferromagnetic with an effective magnetic
+moment of 1.01 $\mu_B$ per unit cell. The electronic structure shows major
+contributions from Pt-$5d$, Ni-$3d$ and O-$2p$ orbitals with band crossing
+close to the Fermi level. The orbital contribution around 8 eV above the Fermi
+level are from the Pt-$s,p$ orbitals forming a kagome like electronic structure
+confirmed by surface Fermi surface spectral function. We found 20 pairs of
+confirmed Weyl nodes along the magnetic easy axis [100]. These results are
+expected to provide a useful and exciting platform for exploring and
+understanding the magnetic Weyl physics in delafossites.",2212.00579v2
+2022-12-03,Magnetoplasmonics: current challenges and future opportunities,"Plasmonics represents a unique approach to confine and enhance
+electromagnetic radiation well below the diffraction limit, bringing a huge
+potential for novel applications, for instance in energy harvesting,
+optoelectronics, and nanoscale biochemistry. To achieve novel functionalities,
+the combination of plasmonic properties with other material functions has
+become increasingly attractive. In this Perspective, we review the current
+state of the art, challenges, and future opportunities in nanoscale
+magnetoplasmonics, an emerging area aiming to merge magnetism and plasmonics in
+confined geometries to control either plasmons, electromagnetic-induced
+collective electronic excitations, using magnetic properties, or magnetic
+phenomena with plasmons. We begin by highlighting the cornerstones of the
+history and principles of this research field. We then provide our vision of
+its future development by showcasing raising research directions in
+mid-infrared light-driven spintronics and novel materials for
+magnetoplasmonics, such as transparent conductive oxides and hyperbolic
+metamaterials. As well, we provide an overview of recent developments in
+plasmon-driven magnetization dynamics, nanoscale optomagnetism and
+acousto-magnetoplasmonics. We conclude by giving our personal vision of the
+future of this thriving research field.",2212.01684v1
+2023-01-29,Anisotropic magnetic and magnetotransport properties in morphologically distinct Nd0.6Sr0.4MnO3 thin films,"We investigate the magnetic and magnetotransport properties of nanostructured
+Nd0.6Sr0.4MnO3 (NSMO) thin films grown on (100) oriented SrTiO3 (STO)
+substrates. The thin films fabricated using the pulsed laser deposition
+technique have been found to possess two distinct surface morphologies:
+granular and nano rod type. Magnetization measurements have revealed that the
+films with rod-type morphology exhibit improved in-plane magnetic anisotropy.
+Magnetotransport studies have revealed that the granular thin films display a
+characteristic butterfly-shaped low-field magneto-resistive (LFMR) behavior.
+Furthermore, we investigate the anisotropic magneto-resistive (AMR) phenomenon
+in the samples and we find that morphology greatly affects AMR. Thin films with
+rod-type morphology show an enhanced AMR %. Such morphology dependent
+tunability in magnetoresistance properties over a wide temperature range is
+potentially interesting for developing oxide-based sensors and devices.",2301.12406v1
+2023-02-20,Magnetic properties of ferromagnetic Gd$_5$Si$_4$-Fe$_3$O$_4$ bilayer thin film heterostructure,"Magnetic properties of thin films differs from that of the corresponding bulk
+materials and show novel physics as a result of their reduced size and
+dimensionality. Profound changes in magnetic properties can also result with
+exchange bias between the interface of the thin films of different materials.
+Here we present Fe$_3$O$_4$, Gd$_5$Si$_4$ and Fe$_3$O$_4$-Gd$_5$Si$_4$ bilayer
+thin films of varying thicknesses were prepared by RF Magnetron sputtering of
+Fe$_3$O$_4$ and Gd$_5$Si$_4$ targets on silicon substrates in high vacuum.
+Their magnetization was measured at room temperature in fields of 3T and
+between 50 K to 400 K temperatures. Gd5Si4 films resulted in oxidation due to
+the exposure to the air. Deposited film thickness of all the specimens are
+larger than 50nm and show ferromagnetic behavior.",2302.09774v1
+2023-03-26,Strong lateral exchange coupling and current-induced switching in single-layer ferrimagnetic films with patterned compensation temperature,"Strong, adjustable magnetic couplings are of great importance to all devices
+based on magnetic materials. Controlling the coupling between adjacent regions
+of a single magnetic layer, however, is challenging. In this work, we
+demonstrate strong exchange-based coupling between arbitrarily shaped regions
+of a single ferrimagnetic layer. This is achieved by spatially patterning the
+compensation temperature of the ferrimagnet by either oxidation or He+
+irradiation. The coupling originates at the lateral interface between regions
+with different compensation temperature and scales inversely with their width.
+We show that this coupling generates large lateral exchange coupling fields and
+we demonstrate its application to control the switching of magnetically
+compensated dots with an electric current.",2303.14809v1
+2023-04-09,Competing spin-glass and spin-fluctuation states in NdxPr4-xNi3O8,"Neodymium nickelates have attracted research interest due to their strongly
+correlated behaviour and remarkable magnetic properties. More importantly,
+superconductivity has recently been confirmed in thin-film samples of Sr-doped
+NdNiO2, bringing the layered rare earth nickel oxides into the research
+spotlight. In this report, we present results on a series of NdNiO2 analogues,
+NdxPr4-xNi3O8 (x = 0.1, 0.25, 1, 2, and 4) obtained by topotactic reduction, in
+which we observe systematic changes in the magnetic behaviour. As the Nd3+
+content increases, the initially large spin-freezing region with magnetic
+frustration becomes smaller and gradually shifts to low temperatures, while the
+magnetic response gradually increases. The muon-spin spectroscopy measurements
+on Nd4Ni3O8 show that this phenomenon is likely due to the enhancement of spin
+fluctuations in NdxPr4-xNi3O8, which weakens the spin frustration behaviour for
+high Nd3+ contents and at low temperatures. These spin fluctuations can be
+caused by both Nd and Ni ions and could be one of the factors determining the
+occurrence of possible superconductivity.",2304.04263v1
+2023-04-27,Enhanced Critical Field of Superconductivity at an Oxide Interface,"The nature of superconductivity and its interplay with strong spin-orbit
+coupling at the KTaO3(111) interfaces remains a subject of debate. To address
+this problem, we grew epitaxial LaMnO3/KTaO3(111) heterostructures. We show
+that superconductivity is robust against the in-plane magnetic field, with the
+critical field of superconductivity reaching 25 T in optimally doped
+heterostructures. The superconducting order parameter is highly sensitive to
+carrier density. We argue that spin-orbit coupling drives the formation of
+anomalous quasiparticles with vanishing magnetic moment, providing the
+condensate significant immunity against magnetic fields beyond the Pauli
+paramagnetic limit. These results offer design opportunities for
+superconductors with extreme resilience against magnetic field.",2304.14426v1
+2023-09-05,Ruthenium dioxide RuO$_{2}$: effect of the altermagnetism on the physical properties,"Ruthenium oxide with the rutile structure is one of example of altermagnets.
+These systems are characterized by compensated magnetic moments (typical for
+antiferromagnets) and strong time reversal symmetry breaking (typical for
+ferromagnets). However, in such cases, the electronic band structure exhibit
+strong spin splitting along some directions in the momentum space. Occurrence
+of the compensated magnetic textures allows for realization of surfaces with
+specific magnetization, which dependent on the surface orientation and/or its
+termination. Here, we study interplay between the electronic surface states and
+the surface magnetization. We show that the spin-resolved spectra strongly
+depends on a direction in reciprocal space. Such properties can be used for the
+experimental confirmation of the altermagnetism in RuO$_{2}$ within the
+spectroscopic techniques. Additionally, we show that the most modified orbitals
+in the system are $d_{z^{2}}$ and $d_{xy}$ orbitals of Ru. Similarly, the Ru
+$e_{g}$ states are most sensitive on epitaxial strain, what can suggest some
+link between altermagnetism and strain.",2309.02421v1
+2023-12-18,Incommensurate magnetic order: a fingerprint for electronic correlations in hole-doped cuprates,"Intertwined charge and magnetic fluctuations in high-$T_\text{c}$ copper
+oxide superconductors (cuprates) are hypothesized to be a consequence of their
+correlated electronic nature. Among other observables, this is apparent in the
+doping dependence of incommensurate magnetic order, known as the Yamada
+relation (YR). We analyze the Hubbard model to challenge the universality of YR
+as a function of interaction strength $U$ through Kotliar-Ruckenstein
+slave-boson (SB) mean-field theory and truncated unity functional
+renormalization group (TUFRG). While TUFRG tends to lock in to a doping
+dependence of the incommensurate magnetic ordering vector obtained for the
+perturbative weak-coupling limit, SB not only exhibits an enhanced sensitivity
+upon a variation of $U$ from weak to strong coupling, but also shows good
+agreement with experimental data. It supports the placement of weakly
+hole-doped cuprates in the intermediate-to-strong coupling regime.",2312.11628v1
+2024-03-08,3d-oxide molecules to tailor large magnetic anisotropy energies on MgO films,"Designing systems with large magnetic anisotropy energy (MAE) is desirable
+and critical for nanoscale magnetic devices. A recent breakthrough achieved the
+theoretical limit of the MAE for 3$d$ transition metal atoms by placing a
+single Co atom on a MgO(100) surface, a result not replicated by standard
+first-principles simulations. Our study, incorporating Hubbard-$U$ correction
+and spin-orbit coupling, successfully reproduces and explains the high MAE of a
+Co adatom on a MgO (001) surface. We go further by exploring ways to enhance
+MAE in 3d transition metal adatoms through different structural geometries of
+3d--O molecules on MgO. One promising structure, with molecules perpendicular
+to the surface, enhances MAE while reducing substrate interaction, minimizing
+spin fluctuations, and boosting magnetic stability. Additionally, we
+demonstrate significant control over MAE by precisely placing 3d--O molecules
+on the substrate at the atomic level.",2403.05432v1
+2023-08-31,Beyond domain alignment: Revealing the effect of intrinsic magnetic order on electrochemical water splitting,"To reach a long term viable green hydrogen economy, rational design of active
+oxygen evolution reaction (OER) catalysts is critical. An important hurdle in
+this reaction originates from the fact that the reactants are singlet
+molecules, whereas the oxygen molecule has a triplet ground state with parallel
+spin alignment, implying that magnetic order in the catalyst is essential.
+Accordingly, multiple experimentalists reported a positive effect of external
+magnetic fields on OER activity of ferromagnetic catalysts. However, it remains
+a challenge to investigate the influence of the intrinsic magnetic order on
+catalytic activity. Here, we tuned the intrinsic magnetic order of epitaxial
+La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ thin film model catalysts from ferro- to
+paramagnetic by changing the temperature in-situ during water electrolysis.
+Using this strategy, we show that ferromagnetic ordering below the Curie
+temperature enhances OER activity. Moreover, we show a slight current density
+enhancement upon application of an external magnetic field and find that the
+dependence of magnetic field direction correlates with the magnetic anisotropy
+in the catalyst film. Our work thus suggests that both the intrinsic magnetic
+order in La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ films and magnetic domain alignment
+increase their catalytic activity. We observe no long-range magnetic order at
+the catalytic surface, implying that the OER enhancement is connected to the
+magnetic order of the bulk catalyst. Combining the effects found with existing
+literature, we propose a unifying picture for the spin-polarized enhancement in
+magnetic oxide catalysts.",2308.16654v1
+2004-05-06,Application of Kondo-lattice theory to Mott-Hubbard metal-insulator crossover in disordered cuprate-oxide superconductors,"A theory of Kondo lattices is applied to the crossover between local-moment
+magnetism and itinerant-electron magnetism in the t-J model on a quasi-two
+dimensional lattice. The Kondo temperature T_K is defined as a characteristic
+temperature or energy scale of local quantum spin fluctuations. Magnetism with
+T_N >> T_K, where T_N is the N\eel temperature, is characterized as
+local-moment one, while magnetism with T_N << T_K is characterized as
+itinerant-electron one. The Kondo temperature, which also gives a measure of
+the strength of the quenching of magnetic moments, is renormalized by the Fock
+term of the superexchange interaction. Because the renormalization depends on
+life-time widths \gamma of quasiparticles in such a way that T_K is higher for
+smaller \gamma, T_N can be controlled by disorder. The asymmetry of T_N between
+electron-doped and hole-doped cuprates must mainly arise from that of disorder;
+an almost symmetric behavior of T_N must be restored if we can prepare
+hole-doped and electron-doped cuprates with similar degree of disorder to each
+other. Because effective disorder is enhanced by magnetic fields in Kondo
+lattices, antiferromagnetic ordering must be induced by magnetic fields in
+cuprates that exhibit large magnetoresistance.",0405101v2
+2007-01-22,New Consideration on Composed Nonextensive Magnetic Systems,"In this paper a composed A+B magnetic system, with spins J_A=2 and J_B=3/2,
+is considered within the mean-field approximation, in the framework of Tsallis
+nonextensive statistics. Our motivation is twofold: (1) to approach the
+existing experimental data of manganese oxides (manganites), where Mn^{3+} and
+Mn^{4+} form two magnetic sublattices, and (2) to investigate the structure of
+nonextensive density matrices of composed systems. By imposing that
+thermodynamic quantities, such as the magnetization of sublattices A and B,
+must be invariant weather the calculation is taken over the total Hilbert space
+or over partial subspaces, we found that the expression for the nonextensive
+entropy must be adapted. Our argument is supported by calculation of
+sublattices magnetization M_A and M_B, internal energy, U_A and U_B, and
+magnetic specific heat, CA and CB. It is shown that only with the modified
+entropy the two methods of calculation agree to each other. Internal energy and
+magnetization are additive, but no clear relationship was found between S_A,
+S_B and the total entropy S_{A+B} for q \neq 1. It is shown that the reason for
+the failure of the standard way of calculation is the assumption of statistical
+independence between the two subsystems, which however does not affect the
+density matrix in the full Hilbert space.",0701495v3
+2010-11-30,Structural and magnetic properties of the ordered perovskite Pb2CoTeO6,"The complex perovskite Pb2CoTeO6 (PCTO) has been prepared as polycrystalline
+powders by solid state reaction route, and the crystal structure and magnetic
+properties have been investigated using a combination of X-ray and neutron
+powder diffraction, electron microscopy, dielectric, calorimetric and magnetic
+measurements. It was shown that at room temperature this compound adopts a
+trigonal perovskite structure, space group R-3 (a= 5.6782(1){\AA}, c=
+13.8552(3){\AA}). The compound undergoes a number of temperature-induced phase
+transitions and adopts four different structures in the temperature range 5-500
+K: monoclinic in P21/n(5<T<125K, tilt system (a+b-b-)), monoclinic in I2/m
+(125<T<210 K, tilt system (a0b-b-)), rhombohedral in R-3 (210<T<370K, tilt
+system (a-a-a-)), and finally cubic in Fm-3m (above 370K without any tilting).
+These structural phase transitions are coupled to a change in the dielectric
+constant and the heat capacity around 210 and 370K. A long-range
+antiferromagnetically ordered state has been identified from neutron powder
+diffraction and magnetic studies at different temperatures. Magnetic
+diffraction peaks were registered below the transition at about 16 K and a
+possible model for the magnetic structure is proposed. Possible coexistence of
+long-range ordering of electrical dipoles and magnetic moments at low
+temperatures making PCTO a multiferroic candidate is discussed and compared
+with those of other Co-based quaternary oxides adopting the perovskite
+structure.",1011.6638v1
+2011-06-30,Formation of magnetic glass in calcium doped YBaCo2O5.5 cobaltites,"The d.c. magnetization and magnetic relaxation studies of the calcium doped
+samples, Y0.95Ca0.05BaCo2O5.5 and YBa0.95Ca0.05Co2O5.5, show the existence of a
+magnetic glass like behaviour in the family of cobaltites for the first time.
+Our investigations reveal glass-like arrest of kinetics at low temperature
+which prevents the system from reaching its magnetic ground state. We show that
+the low temperature state of these calcium doped phases, which consists of
+coexisting antiferromagnetic and ferro (or ferri) magnetic phase fractions, can
+be tuned in a number of ways. Our observations establish that the low
+temperature state of this oxide is not in thermal equilibrium. The glassy state
+is formed with the assistance of an external magnetic field, which makes it
+distinctly different from the more well known metastable state, the spin glass
+state. The cooling field can tune the fractions of the coexisting phases, and
+the glass-like state formed at low temperature can also be devitrified by
+warming the sample. The role of Ca doping in the appearance of these phenomena
+is discussed in terms of phase separation, involving Co3+ disproportionation
+into Co4+ ferromagnetic clusters and Co2+ antiferromagnetic clusters.",1106.6253v1
+2012-09-25,Strong magnetic field effect on above-barrier transport in Pb-p-HgCdTe Schottky barriers,"Due to large difference in effective masses of light and heavy holes it is
+usually supposed that the above-barrier current in Schottky barriers on p-type
+semiconductor is controlled only by the heavy holes. However, in real
+structures, there is an additional potential barrier caused by a oxide layer at
+interface. For typical values of thickness and height of a barrier its tunnel
+transparency for light holes can be higher by three order of magnitude than
+that for heavy holes. Due to such separative role of insulator layer one can
+expect that the current is manly a contribution of light holes. To clear up
+this problem the investigation of transport in a magnetic field is used as a
+key experiment in this work. The pronounced magnetic field effect for heavy
+holes in investigated Pb-p-HgCdTe Schottky barriers is expected only at
+extremely strong magnetic fields B>10 T within the framework of both diode and
+diffusion mechanism of transport. At the same time experimentally more than
+twofold decrease in saturation current is observed even at B=0.5 T at any
+orientation of magnetic field. The studies performed for HgCdTe with different
+Kane's gap and at different temperatures show that the magnitude of magnetic
+field effect is uniquely determined by the ratio of light hole cyclotron energy
+to a thermal energy. However the magnitude of effect exceeds considerably the
+prediction of the simple theory and the experimental magnetic field
+dependencies of a saturation current do not follow the simple exponential
+falling predicted for thermionic current. The reason of this discrepancy
+remains a mystery.",1209.5528v1
+2012-11-15,Electrical Investigation of the Oblique Hanle Effect in Ferromagnet/Oxide/Semiconductor Contacts,"We have investigated the electrical Hanle effect with magnetic fields applied
+at an oblique angle ({\theta}) to the spin direction (the oblique Hanle effect,
+OHE) in CoFe/MgO/semiconductor (SC) contacts by employing a three-terminal
+measurement scheme. The electrical oblique Hanle signals obtained in
+CoFe/MgO/Si and CoFe/MgO/Ge contacts show clearly different line shapes
+depending on the spin lifetime of the host SC. Notably, at moderate magnetic
+fields, the asymptotic values of the oblique Hanle signals (in both contacts)
+are consistently reduced by a factor of cos^2({\theta}) irrespective of the
+bias current and temperature. These results are in good agreement with
+predictions of the spin precession and relaxation model for the electrical
+oblique Hanle effect. At high magnetic fields where the magnetization of CoFe
+is significantly tilted from the film plane to the magnetic field direction, we
+find that the observed angular dependence of voltage signals in the CoFe/MgO/Si
+and CoFe/MgO/Ge contacts are well explained by the OHE, considering the
+misalignment angle between the external magnetic field and the magnetization of
+CoFe.",1211.3486v4
+2013-11-04,Interplay of many-body and single-particle interactions in iridates and rhodates,"Motivated by recent experiments exploring the spin-orbit-coupled magnetism in
+$4d$- and $5d$-band transition metal oxides, we study magnetic interactions in
+Ir- and Rh-based compounds. In these systems, the comparable strength of
+spin-orbit coupling (SOC), crystal field splitting (CF) and Coulomb and Hund's
+coupling leads to a rich variety of magnetic exchange interactions, leading to
+new types of ground states. Using a strong coupling approach, we derive
+effective low-energy super-exchange Hamiltonians from the multi-orbital Hubbard
+model by taking full account of the Coulomb and Hund's interactions in the
+intermediate states. We find that in the presence of strong SOC and lattice
+distortions the super-exchange Hamiltonian contains various kinds of magnetic
+anisotropies.
+  Here we are primarily interested in the magnetic properties of Sr$_2$IrO$_4$
+and Sr$_2$Ir$_{1-x}$Rh$_x$O$_4$ compounds. We perform a systematic study of how
+magnetic interactions in these systems depend on the microscopic parameters and
+provide a thorough analysis of the resulting magnetic phase diagram. Comparison
+of our results with experimental data shows good agreement. Finally, we discuss
+the parameter space in which the spin-flop transition in Sr$_2$IrO$_4$,
+experimentally observed under pressure, can be realized.",1311.0852v2
+2014-12-23,Field-induced inter-planar correlations in the high-temperature superconductor La1.88Sr0.12CuO4,"We present neutron scattering studies of the inter-planar correlations in the
+high-temperature superconductor La1.88Sr0.12CuO4 (T_c=27 K). The correlations
+are studied both in a magnetic field applied perpendicular to the CuO2 planes,
+and in zero field under different cooling conditions. We find that the effect
+of the magnetic field is to increase the magnetic scattering signal at all
+values of the out-of-plane wave vector L, indicating an overall increase of the
+magnetic moments. In addition, weak correlations between the copper oxide
+planes develop in the presence of a magnetic field. This effect is not taken
+into account in previous reports on the field effect of magnetic scattering,
+since usually only L~0 is probed. Interestingly, the results of quench-cooling
+the sample are similar to those obtained by applying a magnetic field. Finally,
+a small variation of the incommensurate peak position as a function of L
+provides evidence that the incommensurate signal is twinned with the dominating
+and sub-dominant twin displaying peaks at even or odd L, respectively.",1412.7329v1
+2015-05-05,Large spin Hall magnetoresistance and its correlation to the spin-orbit torque in W/CoFeB/MgO structures,"The spin-orbit interaction in heavy metal/ferromagnet/oxide structures has
+been extensively investigated because it can be employed in manipulation of the
+magnetization direction by in-plane current. This implies the existence of an
+inverse effect, in which the conductivity in such structures should depend on
+the magnetization orientation. In this work, we report a systematic study of
+the magnetoresistance (MR) of the W/CoFeB/MgO structures and its correlation to
+the current-induced torque to the magnetization. We observe that the MR is
+independent of the angle between magnetization and current direction, but is
+determined by the relative magnetization orientation with respect to the spin
+direction accumulated by spin Hall effect, which is the same symmetry of
+so-called spin Hall magnetoresistance. The MR of ~1% in W/CoFeB/MgO samples is
+considerably larger than those in other structures of Ta/CoFeB/MgO or
+Pt/Co/AlOx, which indicates a larger spin Hall angle of W. Moreover, the
+similar W thickness dependence of the MR and the current-induced magnetization
+switching efficiency demonstrates that they share the same underlying physics,
+which allows one to utilize the MR in non-magnet/ferromagnet structure in order
+to understand closely related other spin-orbit coupling effects such as inverse
+spin Hall effect, spin-orbit spin transfer torques, etc.",1505.00899v1
+2015-09-25,Nanosized helical magnetic domains in strongly frustrated Fe3PO4O3,"Fe3PO4O3 forms a non-centrosymmetric lattice structure (space group R3m)
+comprising triangular motifs of Fe^{3+} coupled by strong antiferromagnetic
+interactions (|\Theta_{CW}| > 900 K). Neutron diffraction from polycrystalline
+samples shows that strong frustration eventually gives way to an ordered
+helical incommensurate structure below T_N = 163 K, with the helical axis in
+the hexagonal ab plane and a modulation length of ~ 86 \AA. The magnetic
+structure consists of an unusual needle-like correlation volume that extends
+past 900 \AA along the hexagonal c-axis but is limited to ~ 70 \AA in the ab
+plane, despite the three-dimensional nature of the magnetic sublattice
+topology. The small in-plane correlation length, which persists to at least T =
+T_N/40, indicates a robust blocking of long-range order of the helical magnetic
+structure, and therefore stable domain walls, or other defect spin textures,
+must be abundant in Fe3PO7. Temperature dependent neutron powder diffraction
+reveals small negative thermal expansion below T_N. No change in lattice
+symmetry is observed on cooling through T_N, as revealed by high resolution
+synchrotron X-ray diffraction. The previously reported reduced moment of the
+Fe^{3+} ions (S=5/2), \mu ~ 4.2 \mu_B, is confirmed here through magnetization
+studies of a magnetically diluted solid solution series of compounds,
+Fe3-xGaxPO4O3, and is consistent with the refined magnetic moment from neutron
+diffraction 4.14(2) \mu_B. We attribute the reduced moment to a modified spin
+density distribution arising from ligand charge transfer in this insulating
+oxide.",1509.07846v2
+2016-02-20,Covalent bonds against magnetism in transition metal compounds,"Magnetism in transition metal compounds is usually considered starting from a
+description of isolated ions, as exact as possible, and treating their
+(exchange) interaction at a later stage. We show that this standard approach
+may break down in many cases, especially in $4d$ and $5d$ compounds. We argue
+that there is an important intersite effect -- an orbital-selective formation
+of covalent metal-metal bonds, which leads to an ""exclusion"" of corresponding
+electrons from the magnetic subsystem, and thus strongly affects magnetic
+properties of the system. This effect is especially prominent for noninteger
+electron number, when it results in suppression of the famous double exchange,
+the main mechanism of ferromagnetism in transition metal compounds. We study
+this novel mechanism analytically and numerically and show that it explains
+magnetic properties of not only several $4d-5d$ materials, including
+Nb$_2$O$_2$F$_3$ and Ba$_5$AlIr$_2$O$_{11}$, but can also be operative in $3d$
+transition metal oxides, e.g. in CrO$_2$ under pressure. We also discuss the
+role of spin-orbit coupling on the competition between covalency and magnetism.
+Our results demonstrate that strong intersite coupling may invalidate the
+standard single-site starting point for considering magnetism, and can lead to
+a qualitatively new behaviour.",1602.06425v2
+2013-09-07,High temperature non-collinear magnetism in a classical bilinear-biquadratic Heisenberg model,"Motivated by the magnetically-driven high-temperature ferroelectric behavior
+of CuO and the subsequent theoretical efforts to understand this intriguing
+phenomenon, we study a spin model on a two-dimensional square lattice which
+possesses some of the key features of the models proposed for CuO. The model
+consists of Heisenberg couplings between nearest and next-nearest neighbor
+spins, and biquadratic couplings between nearest neighbors. We use a
+combination of variational calculations and classical Monte Carlo simulations
+to study this model at zero and finite temperatures. We show that even an
+arbitrarily weak biquadratic coupling plays a crucial role in selecting the
+magnetic ground state. More importantly, a non-collinear magnetic state,
+characterized by a finite spin current, is stable at finite temperatures. The
+interesting aspect is that the present model neither includes an
+inversion-symmetry-breaking term nor the effects of lattice distortions in the
+Hamiltonian. We conclude that non-collinear magnetism at high temperatures, as
+observed in CuO, can be explained via pure spin Hamiltonians. We find that the
+spiral phase is inhomogeneous, and is stabilized by entropic effects. Our study
+demonstrates that higher order interaction terms are of crucial importance if
+the stronger interactions together with the lattice geometry contemplate to
+generate a near degeneracy of magnetic states. The conclusions presented in
+this work are of particular relevance to the non-collinear magnetism and
+ferroelectricity observed at high temperatures in cupric oxide.",1309.1874v1
+2017-07-16,First Principles Study of the Giant Magnetic Anisotropy Energy in Bulk Na4IrO4,"In 5d transition metal oxides, novel properties arise from the interplay of
+electron correlations and spin--orbit interactions. Na4IrO4, where 5d
+transition-metal Ir atom occupies the center of the square-planar coordination
+environment, is synthesized. Based on density functional theory, we calculate
+its electronic and magnetic properties. Our numerical results show that the
+Ir-5d bands are quite narrow, and the bands around the Fermi level are mainly
+contributed by d_{xy},d_{yz} and d_{zx} orbitals. The magnetic easy-axis is
+perpendicular to the IrO4 plane, and the magnetic anisotropy energy (MAE) of
+Na4IrO4 is found to be very giant. We estimate the magnetic parameters by
+mapping the calculated total energy for different spin configurations onto a
+spin model. The next nearest neighbor exchange interaction J2 is much larger
+than other intersite exchange interactions and results in the magnetic ground
+state configuration. Our study clearly demonstrates that the huge MAE comes
+from the single-ion anisotropy rather than the anisotropic interatomic spin
+exchange. This compound has a large spin gap but very narrow spin-wave
+dispersion, due to the large single-ion anisotropy and relatively small
+exchange couplings. Noticing this remarkable magnetic feature originated from
+its highly isolated IrO4 moiety, we also explore the possiblity to further
+enhance the MAE.",1707.04865v1
+2017-10-09,Huge magnetoresistance and ultra-sharp metamagnetic transition in polycrystalline ${Sm_{0.5}Ca_{0.25}Sr_{0.25}MnO_3}$,"Large magnetoresistive materials are of immense interest for a number of
+spintronic applications by developing high density magnetic memory devices,
+magnetic sensors and magnetic switches. Colossal magnetoresistance, for which
+resistivity changes several order of magnitude (${\sim10^4 \%}$) in an external
+magnetic field, occurs mainly in phase separated oxide materials, namely
+manganites, due to the phase competition between the ferromagnetic metallic and
+the antiferromagnetic insulating regions. Can one further enhance the
+magnetoresistance by tuning the volume fraction of the two phases? In this
+work, we report a huge colossal magnetoresistance along with the ultra-sharp
+metamagnetic transition in half doped ${Sm_{0.5}Ca_{0.25}Sr_{0.25}MnO_3}$
+manganite compound by suitably tuning the volume fraction of the competing
+phases. The obtained magnetoresistance value at 10 K is as large as
+$\sim10^{13}\%$ in a 30 kOe external magnetic field and $\sim10^{15}\%$ in 90
+kOe external magnetic field and is several orders of magnitude higher than any
+other observed magnetoresistance value reported so far. Using model Hamiltonian
+calculations we have shown that the inhomogeneous disorder, deduced from
+tunneling electron microscopy, suppresses the CE-type phase and seeds the
+ferromagnetic metal in an external magnetic field.",1710.03007v2
+2019-07-13,"Detection of Influenza A Virus Nucleoprotein Through the Self-Assembly of Nanoparticles in Magnetic Particle Spectroscopy-Based Bioassays: A Method for Rapid, Sensitive, and Wash-free Magnetic Immunoassays","Magnetic nanoparticles (MNPs) with proper surface functionalization have been
+extensively applied as labels for magnetic immunoassays, carriers for
+controlled drug/gene delivery, tracers and contrasts for magnetic imaging, etc.
+Here, we introduce a new biosensing scheme based on magnetic particle
+spectroscopy (MPS) and the self-assembly of MNPs to quantitatively detect H1N1
+nucleoprotein molecules. MPS monitors the harmonics of oscillating MNPs as a
+metric for the freedom of rotational motion, thus indicating the bound states
+of MNPs. These harmonics can be readily collected from nanogram quantities of
+iron oxide nanoparticles within 10 s. H1N1 nucleoprotein molecule hosts
+multiple different epitopes that forms binding sites for many IgG polyclonal
+antibodies. Anchoring IgG polyclonal antibodies onto MNPs triggers the
+cross-linking between MNPs and H1N1 nucleoprotein molecules, thereby forming
+MNP self-assemblies. Using MPS and the self-assembly of MNPs, we achieved the
+sensitivity of 44 nM (442 pmole) for detecting H1N1 nucleoprotein. In addition,
+the morphologies and the hydrodynamic sizes of the MNP self-assemblies are
+characterized to verify the MPS results. Different MNP self-assembly models
+such as classical cluster, open ring tetramer, chain model as well as multimers
+(from dimer to pentamer) are proposed in this paper. Herein, we claim the
+feasibility of using MPS and the self-assembly of MNPs as a new biosensing
+scheme for detecting ultralow concentrations of target biomolecules, which can
+be employed as rapid, sensitive, and wash-free magnetic immunoassays.",1907.06000v1
+2020-12-21,Development of short and long-range magnetic order in the double perovskite based frustrated triangular lattice antiferromagnet Ba2MnTeO6,"Oxide double perovskites wherein octahedra formed by both 3d elements and
+sp-based heavy elements give rise to unconventional magnetic ordering and
+correlated quantum phenomena crucial for futuristic applications. Here, by
+carrying out experimental and first principles investigations, we present the
+electronic structure and magnetic phases of Ba2MnTeO6, where Mn^2+ ions with S
+= 5/2 spins constitute a perfect triangular lattice. The magnetic
+susceptibility reveals a large Curie- Weiss temperature -152 K suggesting the
+presence of strong antiferromagnetic interactions between Mn^2+ moments in the
+spin lattice. A phase transition at 20 K is revealed by magnetic susceptibility
+and specific heat which is attributed to the presence of a sizeable inter-plane
+interactions. Below the transition temperature, the specific heat data show
+antiferromagnetic magnon excitations with a gap of 1.4 K. Furthermore, muon
+spin-relaxation reveals the presence of static internal fields in the ordered
+state and provides strong evidence of short-range spin correlations for T > TN.
+The DFT+U calculations and spin-dimer analysis infer that Heisenberg
+interactions govern the inter and intra-layer spin-frustrations in this
+perovskite. The inter and intra-layer exchange interactions are of comparable
+strengths (J1 = 4.6 K, J2 = 0.92 J1). However, a weak third nearest-neighbor
+ferromagnetic inter-layer interaction exists (J3=-0.04 J1) due to
+double-exchange interaction via the linear path Mn-O-Te-O-Mn. The combined
+effect of J2 and J3 interactions stabilizes a three dimensional long-range
+magnetic ordering in this frustrated magnet.",2012.11292v1
+2018-05-31,Resonate and Fire Neuron with Fixed Magnetic Skyrmions,"In the brain, the membrane potential of many neurons oscillates in a
+subthreshold damped fashion and fire when excited by an input frequency that
+nearly equals their eigen frequency. In this work, we investigate theoretically
+the artificial implementation of such ""resonate-and-fire"" neurons by utilizing
+the magnetization dynamics of a fixed magnetic skyrmion in the free layer of a
+magnetic tunnel junction (MTJ). To realize firing of this nanomagnetic
+implementation of an artificial neuron, we propose to employ voltage control of
+magnetic anisotropy or voltage generated strain as an input (spike or
+sinusoidal) signal, which modulates the perpendicular magnetic anisotropy
+(PMA). This results in continual expansion and shrinking (i.e. breathing) of a
+skyrmion core that mimics the subthreshold oscillation. Any subsequent input
+pulse having an interval close to the breathing period or a sinusoidal input
+close to the eigen frequency drives the magnetization dynamics of the fixed
+skyrmion in a resonant manner. The time varying electrical resistance of the
+MTJ layer due to this resonant oscillation of the skyrmion core is used to
+drive a Complementary Metal Oxide Semiconductor (CMOS) buffer circuit, which
+produces spike outputs. By rigorous micromagnetic simulation, we investigate
+the interspike timing dependence and response to different excitatory and
+inhibitory incoming input pulses. Finally, we show that such resonate and fire
+neurons have potential application in coupled nanomagnetic oscillator based
+associative memory arrays.",1806.00076v1
+2021-05-05,Superconductivity assisted change of the perpendicular magnetic anisotropy in V/MgO/Fe junctions,"Controlling the perpendicular magnetic anisotropy (PMA) in thin films has
+received considerable attention in recent years due to its technological
+importance. PMA based devices usually involve heavy-metal
+(oxide)/ferromagnetic-metal bilayers, where, thanks to interfacial spin-orbit
+coupling (SOC), the in-plane (IP) stability of the magnetization is broken.
+Here we show that in V/MgO/Fe(001) epitaxial junctions with competing in-plane
+and out-of-plane (OOP) magnetic anisotropies, the SOC mediated interaction
+between a ferromagnet (FM) and a superconductor (SC) enhances the effective PMA
+below the superconducting transition. This produces a partial magnetization
+reorientation without any applied field for all but the largest junctions,
+where the IP anisotropy is more robust; for the smallest junctions there is a
+reduction of the field required to induce a complete OOP transition
+($H_\text{OOP}$) due to the stronger competition between the IP and OOP
+anisotropies. Our results suggest that the degree of effective PMA could be
+controlled by the junction lateral size in the presence of superconductivity
+and an applied electric field. We also discuss how the $H_\text{OOP}$ field
+could be affected by the interaction between magnetic stray fields and
+superconducting vortices. Our experimental findings, supported by numerical
+modelling of the ferromagnet-superconductor interaction, open pathways to
+active control of magnetic anisotropy in the emerging dissipation-free
+superconducting spin electronics.",2105.02050v4
+2021-06-09,Magnetic properties of the quasi two-dimensional centered honeycomb antiferromagnet GdInO$_3$,"The crystal structure and magnetic property of the single crystalline
+hexagonal rare-earth indium oxides GdInO$_3$ have been studied by combing
+experiments and model calculations. The two inequivalent Gd$^{3+}$ ions form
+the centered honeycomb lattice, which consists of honeycomb and triangular
+sublattices. The dc magnetic susceptibility and specific heat measurements
+suggest two antiferromagnetic phase transitions at $T_\textrm{N1}$ = 2.3 K and
+$T_\textrm{N2}$ = 1.02 K. An inflection point is observed in the isothermal
+magnetization curve, which implies an up-up-down phase with a 1/3 magnetization
+plateau. We also observe a large magnetic entropy change originated from the
+magnetic frustration in GdInO$_3$. By considering a classical spin Hamiltonian,
+we establish the ground state phase diagram, which suggests that GdInO$_3$ has
+a weak easy-axis anisotropy and is close to the equilateral triangular-lattice
+system. The theoretical ground-state phase diagram may be used as a reference
+in NMR, ESR, or $\mu$SR experiments in future.",2106.05071v2
+2021-07-13,Investigation of spin-phonon coupling and local magnetic properties in magnetoelectric Fe2TeO6,"Spin-phonon coupling originated from spin-lattice correlation depends upon
+different exchange interactions in transition metal oxides containing 3d
+magnetic ions. Spin-lattice coupling can influence the coupling mechanism in
+magnetoelectric material. To understand the spin-lattice correlation in inverse
+trirutile Fe2TeO6 (FTO), magnetic properties and phonon spectra are studied.
+Signature of short-range magnetic correlation induced by 5/2-5/2 dimeric
+interaction and magnetic anomaly at 150 K is perceived apart from the familiar
+sharp transition (TN~210K) corresponding to long-range order by magnetization
+and heat capacity measurement. The magnetic transitions and the spin dynamics
+are further locally probed by muon spin resonance ({\mu}SR) measurement in both
+zero fields (ZF) and longitudinal field (LF) mode. Three dynamically distinct
+temperature regimes; (i) T >TN, (ii) TN>T>150 K, and (iii) T<150 K, are
+observed. A swift change in spin dynamics is realized at 150K by {\mu}SR,
+though previous studies suggest long-range antiferromagnetic order. The
+observation of renormalization of different Raman modes below 210K suggests the
+existence of spin-phonon coupling in the material. The coupling strength is
+quantified as in the range 0.1-1.2 cm-1 following the two-spin cluster
+approximation. We propose that the spin-phonon coupling is mediated by the
+Fe-O2-Fe interbilayer exchange play a significant role in ME coupling observed
+in the material.",2107.06269v2
+2021-09-16,Highly Tunable Magnetic and Magnetotransport Properties of Exchange Coupled Ferromagnet/Antiferromagnet-based Heterostructures,"Antiferromagnets (AFMs) with zero net magnetization are proposed as active
+elements in future spintronic devices. Depending on the critical thickness of
+the AFM thin films and the measurement temperature, bimetallic Mn-based alloys
+and transition metal oxide-based AFMs can host various coexisting ordered,
+disordered, and frustrated AFM phases. Such coexisting phases in the exchange
+coupled ferromagnetic (FM)/AFM-based heterostructures can result in unusual
+magnetic and magnetotransport phenomena. Here, we integrate chemically
+disordered AFM IrMn3 thin films with coexisting AFM phases into complex
+exchange coupled MgO(001)/Ni3Fe/IrMn3/Ni3Fe/CoO heterostructures and study the
+structural, magnetic, and magnetotransport properties in various magnetic field
+cooling states. In particular, we unveil the impact of rotating the relative
+orientation of the disordered and reversible AFM moments with respect to the
+irreversible AFM moments on the magnetic and magnetoresistance properties of
+the exchange coupled heterostructures. We further found that the persistence of
+AFM grains with thermally disordered and reversible AFM order is crucial for
+achieving highly tunable magnetic properties and multi-level magnetoresistance
+states. We anticipate that the introduced approach and the heterostructure
+architecture can be utilized in future spintronic devices to manipulate the
+thermally disordered and reversible AFM order at the nanoscale.",2109.08136v1
+2022-01-15,Tailoring epitaxial growth and magnetism in La1-xSrxMnO3 / SrTiO3 heterostructures via temperature-driven defect engineering,"Among the class of strongly-correlated oxides, La1-xSrxMnO3 $-$ a half
+metallic ferromagnet with a Curie temperature above room temperature $-$ has
+sparked a huge interest as a functional building block for memory storage and
+spintronic applications. In this respect, defect engineering has been in the
+focus of a long-standing quest for fabricating LSMO thin films with highest
+quality in terms of both structural and magnetic properties. Here, we discuss
+the correlation between structural defects, such as oxygen vacancies and
+impurity islands, and magnetism in La0.74Sr0.26MnO3/SrTiO3 (LSMO/STO) epitaxial
+heterostructures by systematic control of the growth temperature and
+post-deposition annealing conditions. Upon increasing the growth temperature
+within the 500 $-$ 700 $^{\circ}$C range, the epitaxial LSMO films experience a
+progressive improvement in oxygen stoichiometry, leading to enhanced magnetic
+characteristics. Concurrently, however, the use of a high growth temperature
+triggers the diffusion of impurities from the bulk of STO, which cause the
+creation of off-stoichiometric, dendritic-like SrMoOx islands at the
+film/substrate interface. As a valuable workaround, post-deposition annealing
+of the LSMO films grown at a relatively-low temperature of about 500
+$^{\circ}$C permits to obtain high-quality epitaxy, atomically-flat surface as
+well as a sharp magnetic transition above room temperature and robust
+ferromagnetism. Furthermore, under such optimized fabrication conditions
+possible scenarios for the formation of the magnetic dead layer as a function
+of LSMO film thickness are discussed. Our findings offer effective routes to
+finely tailor the complex interplay between structural and magnetic properties
+of LSMO thin films via temperature-controlled defect engineering.",2201.05873v1
+2022-02-09,"Ferromagnetism induced by hybridization of Fe 3d orbitals with ligand InSb bands in n-type ferromagnetic semiconductor (In,Fe)Sb","Fe-doped III-V ferromagnetic semiconductor (FMS) (In,Fe)Sb is a promising
+material for spintronic device applications because of the n-type carrier
+conduction and the ferromagnetism with high Curie temperature (TC > 300 K). To
+clarify the mechanism of the high-TC ferromagnetism, we have investigated the
+electronic structure and magnetic properties of an (In,Fe)Sb thin film by
+performing x-ray absorption spectroscopy (XAS) and x-ray magnetic circular
+dichroism (XMCD) measurements at the Fe L2,3 edges. The magnetic-field
+dependence of the XMCD spectra reveals that there are ferromagnetic-like Fe and
+paramagnetic-like Fe components in the (In,Fe)Sb thin film. The XAS and XMCD
+spectra of the ferromagnetic-like and paramagnetic-like Fe components resemble
+those of other Fe-doped FMSs and extrinsic oxides, respectively. The finite
+value of the ratio between the orbital and spin magnetic moments estimated by
+applying the XMCD sum rules indicates that the valence state of the Fe ions
+substituting for the In sites in (In,Fe)Sb is not purely ionic Fe3+, but
+intermediate between Fe3+ and Fe2+. The qualitative correspondence between the
+magnetic-field dependence of the visible-light magnetic circular dichroism
+intensity and that of the XMCD intensity demonstrates that the Zeeman splitting
+of the InSb band is proportional to the net magnetization of the doped Fe.
+These results suggest that the ferromagnetism of (In,Fe)Sb originates from the
+Fe 3d orbitals hybridized with the host InSb bands.",2202.04286v1
+2023-05-30,Aging and passivation of magnetic properties in Co/Gd bilayers,"Synthetic ferrimagnets based on Co and Gd bear promise for directly bridging
+the gap between volatile information in the photonic domain and non-volatile
+information in the magnetic domain, without the need for any intermediary
+electronic conversion. Specifically, these systems exhibit strong spin-orbit
+torque effects, fast domain wall motion and single-pulse all-optical switching
+of the magnetization. An important open challenge to bring these materials to
+the brink of applications is to achieve long-term stability of their magnetic
+properties. In this work, we address the time-evolution of the magnetic moment
+and compensation temperature of magnetron sputter grown Pt/Co/Gd trilayers with
+various capping layers. Over the course of three months, the net magnetic
+moment and compensation temperature change significantly, which we attribute to
+quenching of the Gd magnetization. We identify that intermixing of the capping
+layer and Gd is primarily responsible for this effect, which can be alleviated
+by choosing nitrides for capping as long as reduction of nitride to oxide is
+properly addressed. In short, this work provides an overview of the relevant
+aging effects that should be taken into account when designing synthetic
+ferrimagnets based on Co and Gd for spintronic applications.",2305.18984v1
+2023-08-08,Room temperature reversible colossal volto-magnetic effect in all-oxide metallicmagnet/topotactic-phase-transition material heterostructures,"Multiferroic materials have undergone extensive research in the past two
+decades in an effort to produce a sizable room-temperature magneto-electric
+(ME) effect in either exclusive or composite materials for use in a variety of
+electronic or spintronic devices. These studies have looked into the ME effect
+by switching the electric polarization by the magnetic field or switching the
+magnetism by the electric field. Here, an innovative way is developed to knot
+the functional properties based on the tremendous modulation of electronics and
+magnetization by the electric field of the topotactic phase transitions (TPT)
+in heterostructures composed of metallic-magnet/TPT-material. It is divulged
+that application of a nominal potential difference of 2-3 Volts induces
+gigantic changes in magnetization by 100-250% leading to colossal Voltomagnetic
+effect, which would be tremendously beneficial for low-power consumption
+applications in spintronics. Switching electronics and magnetism by inducing
+TPT through applying an electric field requires much less energy, making such
+TPT-based systems promising for energy-efficient memory and logic applications
+as well as opening a plethora of tremendous opportunities for applications in
+different domains.",2308.04324v1
+1994-07-12,Transport Properties of the Kondo Lattice Model in the Limit $S=\infty$ and $D=\infty$,"The Kondo lattice model with Hund's ferromagnetic spin coupling is
+investigated as a microscopic model of the perovskite-type 3d transition-metal
+oxide La$_{1-x}$Sr$_x$MnO$_3$. In the classical spin limit $S=\infty$ and the
+infinite-dimensional limit $D=\infty$, the one-body Green's function is
+calculated exactly. Transport properties of the system in the presence of
+magnetic fields are calculated. The giant magnetoresistance of this model,
+which is in a good agreement with the experimental data of
+La$_{1-x}$Sr$_x$MnO$_3$, is explained by the spin disorder scattering process.",9407052v1
+1997-03-24,A Quantum Chemical Approach to Cohesive Properties of NiO,"We apply ab-initio quantum chemical methods to calculate correlation effects
+on cohesive properties of NiO, thereby extending a recently proposed scheme to
+transition metal oxides with partially filled $d$-bands. We obtain good
+agreement with experiment for the cohesive energy and show that the deviation
+of the lattice constant at the Hartree-Fock level is mainly due to van der
+Waals-like interactions. Correlations enhance the stability of the magnetic
+ground state found at the Hartree-Fock level.",9703201v1
+1997-04-07,Charge ordering in doped manganese oxides: lattice dynamics and magnetic structure,"Based on the Hamiltonian of small polarons with the strong nearest neighbor
+repulsion, we have investigated the charge ordering phenomena observed in
+half-doped manganites R_{1/2}A_{1/2}MnO_3. We have explored possible
+consequences of the charge ordering phase in the half-doped manganites. First,
+we have studied the renormalization of the sound velocity around $T_{CO}$,
+considering the acoustic phonons coupled to the electrons participating in the
+charge ordering. Second, we have found a new antiferromagnetic phase induced by
+the charge ordering, and discussed its role in connection with the specific
+CE-type antiferromagnetic structure observed in half-doped manganites.",9704052v1
+1997-05-09,CrO2: a self-doped double exchange ferromagnet,"Band structure calculations of CrO2 carried out in the LSDA+U approach reveal
+a clear picture of the physics behind the metallic ferromagnetic properties.
+Arguments are presented that the metallic ferromagnetic oxide CrO2 belongs to a
+class of materials in which magnetic ordering exists due to double exchange (in
+this respect CrO2 turns out to be similar to the CMR manganates). It is
+concluded that CrO2 has small or even negative charge transfer gap which can
+result in self-doping. Certain experiments to check the proposed picture are
+suggested.",9705091v1
+1997-08-01,Double exchange magnets: Spin-dynamics in the paramagnetic phase,"The electronic structure of perovskite manganese oxides is investigated in
+terms of a Kondo lattice model with ferromagnetic Hund coupling and
+antiferromagnetic exchange between $t_{2g}$-spins using a finite temperature
+diagonalization technique. Results for the dynamic structure factor are
+consistent with recent neutron scattering experiments for the bilayer manganite
+La$_{1.2}$Sr$_{1.8}$Mn$_2$O$_7$ . The susceptibility shows Curie-Weiss
+behaviour and is used to derive a phase diagram. In the paramagnetic phase
+carriers are characterized as ferromagnetic polarons in an antiferromagnetic
+spin liquid.",9708007v1
+1998-06-06,Percolation of finite-sized objects on a lattice,"We study the percolation of FINITE-SIZED objects on two- and
+three-dimensional lattices. Our motivation stems, on one hand from some recent
+interesting experimental results on transport properties of impurity-doped
+oxide perovskites and on the other hand from the theoretical appeal that this
+problem presents. Our system exhibits a well-defined percolation threshold. We
+estimate the size of magnetic polarons, believed to be the carriers of the
+abovementioned transport. We have also obtained two critical exponents for our
+model, which characterize its universality class.",9806086v1
+1999-09-02,Orbital Polarization and Fluctuation in Manganese Oxides,"In a form which include the mother compound, we studied the extended
+Hubbard-type model with the orbital degeneracy for any doping concentration.
+Meanfield phase diagram and the spin wave excitation in RPA are calculated. It
+turned out that a large orbital polarization is essential to reproduce the
+magnetic phases depending on the doping concentration. Base on this result, we
+discuss the spin canting, the spin wave dispersion, and spin wave stiffness
+from the standing point of the large orbital polarization. We also discuss the
+orbital fluctuation which turned out to be important in the ferromagnetic
+metallic region where the CMR is observed. Spin wave softening near the zone
+boundary is also discussed in this context.",9909023v1
+1999-09-24,Biquadratic interactions and spin-Peierls transition in the spin 1 chain LiVGe2O6,"The magnetic susceptibility of a new one-dimensional, S=1 system, the
+vanadium oxide LiVGe2O6, has been measured. Contrary to previous S=1 chains, it
+exhibits an abrupt drop at 22 K typical of a spin-Peierls transition, and it is
+consistent with a gapless spectrum above this temperature. We propose that this
+behaviour is due to the presence of a significant biquadratic exchange
+interaction, a suggestion supported by quantum chemistry calculations that take
+into account the quasi-degeneracy of the t2g levels.",9909357v1
+2000-07-28,Resistivity of Mixed-Phase Manganites,"The resistivity $\rho_{dc}$ of manganites is studied using a
+random-resistor-network, based on phase-separation between metallic and
+insulating domains. When percolation occurs, both as chemical composition and
+temperature vary, results in good agreement with experiments are obtained.
+Similar conclusions are reached using quantum calculations and microscopic
+considerations. Above the Curie temperature, it is argued that ferromagnetic
+clusters should exist in Mn-oxides. Small magnetic fields induce large
+$\rho_{dc}$ changes and a bad-metal state with (disconnected) insulating
+domains.",0007480v1
+2000-09-08,Charge Ordering and Polaron Formation in the Magnetoresistive Oxide La0.7Ca0.3MnO3,"Neutron scattering has been used to study the nature of the ferromagnetic
+transition in a single crystal of the perovskite La0.7Ca0.3MnO3. Diffuse
+scattering from lattice polarons develops as the Curie temperature is
+approached from below, along with short range polaron correlations that are
+consistent with stripe formation. Both the scattering due to the polaron
+correlations and the anomalous quasielastic component in the magnetic
+fluctuation spectrum maximize very close to T_C, in a manner remarkably similar
+to the resistivity, indicating that they have a common origin.",0009132v1
+2001-05-11,Temperature dependence of the structural parameters of the non-oxide perovskite superconductor MgCNi3,"We report the structural parameters of superconducting MgCxNi3 (x=0.96,
+TC=7.3 K) as a function of temperature, from 2 K to 295 K, determined by
+neutron powder diffraction profile refinement. The compound has the perovskite
+structure over the whole temperature range, with symmetry Pm3m and a=3.81221(5)
+A at 295 K: no structural or long range magnetic ordering transitions were
+observed. The lattice parameter a and the Debye-Waller factors for the
+individual atoms decrease smoothly with decreasing temperature. There are no
+unusual changes of the structural parameters near TC.",0105240v1
+2001-06-21,Superconductivity at 1 K in Cd2Re2O7,"We report the first pyrochlore oxide superconductor Cd2Re2O7.
+Resistivity,magnetic susceptibility,and specific heat measurements on single
+crystals evidence a bulk superconductivity at 1 K. Another phase transition
+found at 200 K suggests that a peculiar electronic structure lies behind the
+superconductivity.",0106421v4
+2001-07-11,Antiferromagnetic ordering in a 90 K copper oxide superconductor,"Using elastic neutron scattering, we evidence a commensurate
+antiferromagnetic Cu(2) order (AF) in the superconducting (SC) high-$\rm T_c$
+cuprate $\rm YBa_2(Cu_{1-y}Co_y)_3O_{7+\delta}$ (y=0.013, $\rm T_c$=93 K). As
+in the Co-free system, the spin excitation spectrum is dominated by a magnetic
+resonance peak at 41 meV but with a reduced spectral weight. The substitution
+of Co thus leads to a state where AF and SC cohabit showing that the CuO$_2$
+plane is a highly antiferromagnetically polarizable medium even for a sample
+where T$_c$ remains optimum.",0107218v2
+2001-08-30,Electronic properties of antidot lattices fabricated by atomic force lithography,"Antidot lattices were fabricated by atomic force lithography using local
+oxidation. High quality finite 20 x20 lattices are demonstrated with periods of
+300 nm. The low temperature magnetoresistance shows well developed
+commensurability oscillations as well as a quenching of the Hall effect around
+zero magnetic field. In addition, we find B periodic oscillations superimposed
+on the classical commensurability peaks at temperatures as high as 1.7 K. These
+observations indicate the high electronic quality of our samples.",0108520v1
+2002-07-04,Formation Mechanisms of Single-Pulse and Secondary Echoes in Systems with a Large Inhomogeneous Broadening of NMR Lines,"In the frames of Mims transformation matrix method the equation for nuclear
+magnetization are obtained describing the dynamics of nuclear spin-systems with
+a strong Larmor and Rabi inhomogeneous broadenings of NMR line in conditions of
+their unequlibrium earlier obtained by the statistical tensors method. As
+example, properties of proton single-pulse echo and its secondary signals in
+probe material (silicon oil) coated on the surface of high-Tc
+superconducting-oxides powder and in metallic hydride are presented.",0207124v1
+2002-08-30,Electronic properties of the novel 4d metallic oxide SrRhO3,"The novel 4d perovskite compound SrRhO3 was investigated by isovalent doping
+studies. The solubility limits of Ca and Ba onto Sr-site were below 80% and
+20%, respectively. Although SrRhO3 was chemically compressed, approximately
+5.7% by the Ca doping, no significant influence was observed on the magnetic
+and electrical properties.",0208591v1
+2002-11-08,Nearly total spin polarization in La2/3Sr1/3MnO3 from tunneling experiments,"We have performed magnetotransport measurements on La2/3Sr1/3MnO3 / SrTiO3 /
+La2/3Sr1/3MnO3 magnetic tunnel junctions. A magnetoresistance ratio of more
+than 1800 % is obtained at 4K, from which we infer an electrode spin
+polarization of at least 95 %. This result strongly underscores the
+half-metallic nature of mixed-valence manganites and demonstrates its
+capability as a spin analyzer. The magnetoresistance extends up to temperatures
+of more than 270K. We argue that these improvements over most previous works
+may result from optimizing the patterning process for oxide heterostructures.",0211158v1
+2003-08-22,Relevance of Cooperative Lattice Effects and Correlated Disorder in Phase-Separation Theories for CMR Manganites,"Previous theoretical investigations of colossal magnetoresistance (CMR)
+materials explain this effect using a ``clustered'' state with preformed
+ferromagnetic islands that rapidly align their moments with increasing external
+magnetic fields. While qualitatively successful, explicit calculations indicate
+drastically different typical resistivity values in two- and three-dimensional
+lattices, contrary to experimental observations. This conceptual bottleneck in
+the phase-separated CMR scenario is resolved here considering the cooperative
+nature of the Mn-oxide lattice distortions. This induces power-law correlations
+in the quenched random fields used in toy models with phase competition. When
+these effects are incorporated, resistor-network calculations reveal very
+similar results in two and three dimensions, solving the puzzle.",0308456v1
+2003-09-30,"Spin glass anomalies in stoichiometric spin-chain oxides, Ca3CoXO6 (X = Rh, Ir and Co)","The results of ac susceptibility (chi) measurements for Ca3CoXO6 (X = Rh, Ir
+and Co) compounds, containing spin-chains separated by Ca ions, are presented.
+All these compounds exhibit an unusually large frequency dependence of ac chi,
+in the vicinity of respective magnetic ordering temperatures, which is normally
+not encountered in conventional spin-glasses. The frequency dependence of ac
+chi, peak temperature is however found to obey Vogel-Fulcher relationship. The
+results thus establish that these compounds are unusual spin-glasses, that too
+among stoichiometric compounds presumably due to geometrical frustration.",0309702v1
+2003-10-20,Spin Blockade in Capacitively Coupled Quantum Dots,"We present transport measurements on a lateral double dot produced by
+combining local anodic oxidation and electron beam lithography. We investigate
+the tunability of our device and demonstrate, that we can switch between
+capacitive and tunnel coupling. In the regime of capacitive coupling we observe
+the phenomenon of spin blockade in a magnetic field and analyze the influence
+of capacitive interdot coupling on this effect.",0310469v1
+2004-03-18,Theory of optical spectral weights in Mott insulators with orbital degrees of freedom,"Introducing partial sum rules for the optical multiplet transitions, we
+outline a unified approach to magnetic and optical properties of strongly
+correlated transition metal oxides. On the example of LaVO$_3$ we demonstrate
+how the temperature and polarization dependences of different components of the
+optical multiplet are determined by the underlying spin and orbital
+correlations dictated by the low-energy superexchange Hamiltonian. Thereby the
+optical data provides deep insight into the complex spin-orbital physics and
+the role played by orbital fluctuations.",0403459v2
+2004-03-30,Valence-electron transfer and a metal-insulator transition in a strongly correlated perovskite oxide,"We present transport and thermal data for the quadruple-perovskites
+MCu3(Ti1-xRux)4O12 where 0 < x < 1. A metal-insulator transition (MIT) occurs
+for Ru concentrations x~0.75. At the same time, the Cu2+ antiferromagnetic
+state is destroyed and it's magnetic entropy suppressed by Ru on a 1:1 basis.
+This implies that each Ru transfers an electron to a Cu ion and thus the MIT
+correlates with filling the Cu 3d shell. The Cu spin entropy in this strongly
+correlated electron material provides a unique probe among MIT systems.",0403742v1
+2004-05-26,An Inhomogeneous Josephson Phase Near the (Super) Conductor-Insulator Transition,"In many cases inhomogeneities are known to exist near the metal (or
+superconductor)- insulator transition, as follows from well-known domain-wall
+arguments. If the conducting regions are large enough, and if they have
+superconducting correlations, it becomes energetically favorable for the system
+to go into a Josephson- coupled zero-resistance state before (i.e. at higher
+resistance than) the material becomes a real metal. We show that this is
+plausible by a simple comparison of the relevant coupling constants. We also
+illustrate using data in the literature on oxide materials as well as
+ultra-thin films, that when this proposed Josephson state is quenched by a
+magnetic field, an insulating, rather then a metallic, state indeed appears.",0405625v1
+2004-11-16,An Interesting Magnetoresistive System: Sr2FeMoO6,"Ordered double perovskite oxides of the general formula, A2BB'O6, have been
+known for several decades to have interesting electronic and magnetic
+properties. However, a recent report of a spectacular negative
+magnetoresistance effect in a specific member of this family, namely Sr2FeMoO6,
+has brought this class of compounds under intense scrutiny. In this small
+review, we present few theoretical and experimental results, describing mainly
+the effects of Fe/Mo antisite defects on the properties of this compound and
+also briefly discuss few other puzzling facts about this fascinating compound",0411400v1
+2005-01-17,"Jahn-Teller stabilization of a ""polar"" metal oxide surface: Fe3O4(001)","Using ab initio thermodynamics we compile a phase diagram for the surface of
+Fe3O4(001) as a function of temperature and oxygen pressures. A hitherto
+ignored polar termination with octahedral iron and oxygen forming a wave-like
+structure along the [110]-direction is identified as the lowest energy
+configuration over a broad range of oxygen gas-phase conditions. This novel
+geometry is confirmed in a x-ray diffraction analysis. The stabilization of the
+Fe3O4(001)-surface goes together with dramatic changes in the electronic and
+magnetic properties, e.g., a halfmetal-to-metal transition.",0501402v1
+2005-02-03,Charge order in the incommensurate compounds $Sr\_{14-x}Ca\_xCu\_{24}O\_{41}$,"The present paper studies, using ab-initio calculations, the influence of the
+incommensurate structural modulations on the low energy physics of the
+$Sr\_{14-x}Ca\_xCu\_{24}O\_{41}$ oxides. On-site, nearest-neighbor and
+next-nearest-neighbor effective parameters were computed within a $t-J+V$ model
+based on the copper magnetic orbitals. The structural modulations appear to be
+the key degree of freedom, responsible for the low energy properties such as
+the electron localization, the formation of dimers in the $x=0$ compound or the
+anti-ferromagnetic order in the $x=13.6$ compound.",0502105v1
+2005-03-04,Orbital excitations in titanates,"Raman scattering is used to observe pronounced electronic excitations around
+230 meV - well above the two-phonon range - in the Mott insulators LaTiO$_3$
+and YTiO$_3$. Based on the temperature, polarization, and photon energy
+dependence, the modes are identified as orbital excitations. The observed
+profiles bear a striking resemblance to magnetic Raman modes in the insulating
+parent compounds of the superconducting cuprates, indicating an unanticipated
+universality of the electronic excitations in transition metal oxides.",0503106v1
+2005-04-11,Atom-optical elements on micro chips,"We describe the realization of atom-optical elements as magnetic waveguide
+potentials, beam splitters and gravitational traps on a microchip. The
+microchip was produced by electroplating gold conductors on an aluminium-oxide
+substrate. The conductors are 30-150 $\mu$m wide and allow for the generation
+of waveguides at large distances to the chip surface, where surface effects are
+negligible. We show that these elements can be integrated on a single chip to
+achieve complex atom-optical circuits.",0504242v2
+2005-05-24,Nanowire Acting as a Superconducting Quantum Interference Device,"We present the results from an experimental study of the magneto-transport of
+superconducting wires of amorphous Indium-Oxide, having widths in the range 40
+- 120 nm. We find that, below the superconducting transition temperature, the
+wires exhibit clear, reproducible, oscillations in their resistance as a
+function of magnetic field. The oscillations are reminiscent of those which
+underlie the operation of a superconducting quantum interference device.",0505577v1
+2005-08-08,23Na NMR Studies of Non-superconducting and Superconducting Na0.35CoO2-1.3H2O (Tc < 1.8 and ~ 4.5 K),"We report 23Na NMR studies of the polycrystalline samples of bilayer hydrated
+cobalt oxides Na0.35CoO2-1.3H2O with the superconducting transition
+temperatures Tc < 1.8 and ~ 4.5 K. The magnitude of the 23Na nuclear
+spin-lattice relaxation rate 23(1/T1) significantly decreased from non-hydrated
+Na0.7CoO2 to the bilayer hydrates. We found that the temperature dependence of
+23(1/T1) of the non-superconducting bilayer hydrate is similar to that of the
+non-hydrated Na0.7CoO2, the spin dynamics of which is understood by A-type
+(intra-layer ferromagnetic and inter-layer antiferromagnetic) spin
+fluctuations. The superconducting phase is located close to the A-type magnetic
+instability.",0508197v1
+2005-10-24,Charge Transfer Excited State Contributions to Polarity Dependent Ferromagnetism in ZnO Diluted Magnetic Semiconductors,"A close link between the charge transfer electronic structures and polarity
+dependent high-TC ferromagnetism of TM2+:ZnO DMSs (TM2+ = 3d ions) is
+demonstrated. Trends in ferromagnetism across the 3d series of TM2+:ZnO DMSs
+predicted from their charge transfer energies reproduce experimental trends
+well. These results provide a unified basis for understanding both n- and
+p-type ferromagnetic oxide DMSs.",0510644v1
+2006-12-27,Strong Aharonov-Bohm oscillations in GaAs two-dimensional holes,"We measured Aharonov-Bohm resistance oscillations in a shallow
+two-dimensional GaAs hole ring structure, defined by local anodic surface
+oxidation. The amplitude of the oscillations is about 10% of the ring
+resistance, the strongest seen in a hole system. In addition we observe
+resistance oscillations as a function of front gate bias at zero magnetic
+field. We discuss the results in light of spin interference in the ring and
+possible applications to spintronics.",0612638v2
+2007-02-18,Phase coherent transport in a side-gated mesoscopic graphite wire,"We investigate the magnetotransport properties of a thin graphite wire
+resting on a silicon oxide substrate. The electric field effect is demonstrated
+with back and side gate electrodes. We study the conductance fluctuations as a
+function of gate voltage, magnetic field and temperature. The phase coherence
+length extracted from weak localization is larger than the wire width even at
+the lowest carrier densities making the system effectively one-dimensional. We
+find that the phase coherence length increases linearly with the conductivity
+suggesting that at 1.7 K dephasing originates mainly from electron-electron
+interactions.",0702401v1
+1999-08-27,Delocalized Supergravity Solutions for Brane/Anti-brane Systems and their Bound States,"We obtain various solutions for D=4 dipoles and their bound states whose U(1)
+fields originate from various form fields in the effective string theories. We
+oxidize such dipole solutions to D=10 to obtain delocalized supergravity
+solutions for the brane/anti-brane pairs and their bound states. We speculate
+on generalized harmonic superposition rules for supergravity solutions for
+(intersecting) brane/anti-brane pairs.",9908182v2
+2007-05-10,A Josephson Junction Microscope for Low-frequency Fluctuators,"The high-Q harmonic oscillator mode of a Josephson junction can be used as a
+novel probe of spurious two-level systems (TLSs) inside the amorphous oxide
+tunnel barriers of the junction. In particular, we show that spectroscopic
+transmission measurements of the junction resonator mode can reveal how the
+coupling magnitude between the junction and the TLSs varies with an external
+magnetic field applied in the plane of the tunnel barrier. The proposed
+experiments offer the possibility of clearly resolving the underlying coupling
+mechanism for these spurious TLSs, an important decoherence source limiting the
+quality of superconducting quantum devices.",0705.1380v1
+2007-11-08,Ferroelectrically induced weak-ferromagnetism in a single-phase multiferroic by design,"We present a strategy to design structures for which a polar lattice
+distortion induces weak ferromagnetism. We identify a large class of
+multiferroic oxides as potential realizations and use density-functional theory
+to screen several promising candidates. By elucidating the interplay between
+the polarization and the Dzyaloshinskii-Moriya vector, we show how the
+direction of the magnetization can be switched between 180$^{\circ}$ symmetry
+equivalent states with an applied electric field.",0711.1331v2
+2008-02-15,Non-intrinsic superconductivity in InN epilayers: role of Indium Oxide,"In recent years there have been reports of anomalous electrical resistivity
+and the presence of superconductivity in semiconducting InN layers. By a
+careful correlation of the temperature dependence of resistivity and magnetic
+susceptibility with structural information from highresolution x-ray
+diffraction measurements we show that superconductivity is not intrinsic to InN
+and is seen only in samples that show traces of oxygen impurity. We hence
+believe that InN is not intrinsically a superconducting semiconductor.",0802.2126v1
+2008-04-24,Two Dimensional Spin-Polarized Electron Gas at the Oxide Interfaces,"The formation of a novel spin-polarized 2D electron gas at the LaMnO$_3$
+monolayer embedded in SrMnO$_3$ is predicted from the first-principles
+density-functional calculations. The La (d) electrons become confined in the
+direction normal to the interface in the potential well of the La layer,
+serving as a positively-charged layer of electron donors. These electrons
+mediate a ferromagnetic alignment of the Mn t$_{2g}$ spins near the interface
+via the Anderson-Hasegawa double exchange and become, in turn, spin-polarized
+due to the internal magnetic fields of the Mn moments.",0804.4023v1
+2008-10-06,Spin polarized current and Andreev transmission in planar superconducting/ferromagnetic Nb/Ni junctions,"We have measured the tunnelling current in Nb/Nb$_x$O$_y$/Ni planar tunnel
+junctions at different temperatures. The junctions are in the intermediate
+transparency regime. We have extracted the current polarization of the
+metal/ferromagnet junction without applying a magnetic field. We have used a
+simple theoretical model, that provides consistent fitting parameters for the
+whole range of temperatures analyzed. We have also been able to gain insight
+into the microscopic structure of the oxide barriers of our junctions.%",0810.0929v1
+2009-01-28,Depth dependent local structures in thin films unraveled by grazing incidence x-ray absorption spectroscopy,"A method of using X-ray absorption spectroscopy (XAS) together with resolved
+grazing incidence geometry for depth profiling atomic, electronic, chemical or
+magnetic local structures in thin films is presented. The quantitative
+deconvolution of thickness-dependent spectral features is performed by fully
+considering both scattering and absorption formalisms. Surface oxidation and
+local structural depth profiles in nanometric FePt films are determined,
+exemplifying the application of the method.",0901.4542v1
+2009-04-27,Accurate evaluation of magnetic coupling between atoms with numerous open-shells : an ab-initio method,"We propose a new ab initio method designed for the accurate calculation of
+effective exchange integrals between atoms with numerous open-shells. This
+method applies to ferromagnetic as well as antiferromagnetic exchange, direct
+or ligand-mediated exchange. Test calculations on high spin transition metal
+oxides such as KNiF3, Ba2CoS3 or YMnO3 exhibit a very good accuracy compared
+either to the best ab initio calculations --when those are feasible-- and with
+experimental evaluations.",0904.4231v2
+2009-05-02,Implications and consequences of ferromagnetism universally exhibited by inorganic nanoparticles,"Occurrence of surface ferromagnetism in inorganic nanoprticles as a universal
+property not only explains many of the unusual magnetic features of oxidic thin
+films, but also suggests its possible use in creating new materials, as
+exemplified by multiferroic BaTiO3 nanoparticles. While the use of Mn-doped ZnO
+and such materials in spintronics appears doubtful, it is possible to have
+materials exhibiting coexistence of (bulk) superconductivity with (surface)
+ferromagnetism.",0905.0183v1
+2010-01-29,Conversion of neutral nitrogen-vacancy centers to negatively-charged nitrogen-vacancy centers through selective oxidation,"The conversion of neutral nitrogen-vacancy centers to negatively charged
+nitrogen-vacancy centers is demonstrated for centers created by ion
+implantation and annealing in high-purity diamond. Conversion occurs with
+surface exposure to an oxygen atmosphere at 465 C. The spectral properties of
+the charge-converted centers are investigated. Charge state control of
+nitrogen-vacancy centers close to the diamond surface is an important step
+toward the integration of these centers into devices for quantum information
+and magnetic sensing applications.",1001.5449v1
+2010-01-30,Magnetoresistance of a spin MOSFET with ferromagnetic MnAs source and drain contacts,"Spin-dependent transport was investigated in a spin metal-oxide-semiconductor
+field-effect transistors (spin MOSFET) with ferromagnetic MnAs source and drain
+(S/D) contacts. The spin MOSFET of bottom-gate type was fabricated by
+photolithography using an epitaxial MnAs film grown on a silicon-on-insulator
+(SOI) substrate. In-plane magnetoresistance showed spin-valve-type hysteretic
+behavior, when the measurements were performed with constant source-drain and
+source-gate biases. By comparing with the magnetization-related resistance
+change resulting from the MnAs contacts, we conclude that the spin-polarized
+electrons are injected from the MnAs source into the Si MOS inversion channel,
+and detected by the MnAs drain.",1002.0057v1
+2010-12-27,Disorder induced superconducting ratchet effect in nanowires,"A dc voltage drop develops along amorphous indium oxide nanowires that are
+exposed to an ac bias source. This voltage is anti-symmetric with magnetic
+field and is characterized by sample specific quasi-periodic magneto-voltage
+oscillations. The voltage magnitude increases with decreasing temperature below
+$T_{C}$ but saturates at low T. As the disorder of the sample is decreased, the
+dc voltage is suppressed. We suggest that this rectification is a manifestation
+of the superconducting ratchet effect in which disorder and geometrical
+confinement play the role of asymmetric pinning centers. This effect
+demonstrates the importance of inherent inhomogeneity and vortex motion in the
+superconductor-insulator transition of disordered superconductors.",1012.5609v1
+2011-01-06,Effective quantum pseudospin-1/2 model for Yb pyrochlore oxides,"An effective quantum pseudospin-1/2 Hamiltonian for Yb_2TM_2O_7 (TM = Ti and
+Sn) is obtained in terms of the atomic Kramers ground doublet of the LS
+coupling and the crystalline electric field, which is almost described with
+J^z=\pm 1/2. It is calculated microscopically as the sum of Anderson's
+superexchange interaction and the magnetic dipole interaction. It is found that
+it shows a strong exchange anisotropy.",1101.1230v1
+2011-03-15,Quantum transport in oxide nanostructures,"We describe magnetotransport experiments performed on Hall crosses made from
+quantum wires at LaAlO3/SrTiO3 interfaces. Shubnikov-de Haas oscillations
+measured in a 14-nm wide structure exhibit modulations that are consistent with
+spin-orbit coupling or valley degeneracies. Hall measurements performed on the
+6 nm-wide Hall cross reveal dissipative coupling to magnetic phases. Hall
+plateaus are observed that deviate significantly from two-dimensional quantum
+Hall counterparts. Non-monotonic dips in the Hall resistance are attributed to
+one-dimensional confinement and spin-orbit coupling.",1103.3036v1
+2011-04-12,Non-monotonic temperature dependence of thermopower in strongly correlated electron systems,"We examine the temperature dependence of thermopower in the single band
+Hubbard model using dynamical mean-field theory. The strong Coulomb interaction
+brings about the coherent-to-incoherent crossover as temperature increases. As
+a result, the thermopower exhibits non-monotonic temperature dependence and
+asymptotically approaches values given by the Mott-Heikes formula. In the light
+of our theoretical result, we discuss the thermopower in some transition metal
+oxides. The magnetic field dependence of the thermopower is also discussed.",1104.2119v4
+2011-04-15,Quantized Landau level spectrum and its density dependence,"Scanning tunneling microscopy and spectroscopy in magnetic field was used to
+study Landau quantization in graphene and its dependence on charge carrier
+density. Measurements were carried out on exfoliated graphene samples deposited
+on a chlorinated SiO2 thermal oxide which allowed observing the Landau level
+sequences characteristic of single layer graphene while tuning the density
+through the Si backgate. Upon changing the carrier density we find abrupt jumps
+in the Fermi level after each Landau level is filled. Moreover, the Landau
+level spacing shows a marked increase at low doping levels, consistent with an
+interaction-induced renormalization of the Dirac cone.",1104.2947v1
+2011-04-25,"Metallic characteristics in superlattices composed of insulators, NdMnO3/SrMnO3/LaMnO3","We report on the electronic properties of superlattices composed of three
+different antiferromagnetic insulators, NdMnO3/SrMnO3/LaMnO3 grown on SrTiO3
+substrates. Photoemission spectra obtained by tuning the x-ray energy at the Mn
+2p -> 3d edge show a Fermi cut-off, indicating metallic behavior mainly
+originating from Mn e_g electrons. Furthermore, the density of states near the
+Fermi energy and the magnetization obey a similar temperature dependence,
+suggesting a correlation between the spin and charge degrees of freedom at the
+interfaces of these oxides.",1104.4694v1
+2011-05-05,Understanding interface effects in perovskite thin films,"The control of matter properties (transport, magnetic, dielectric,...) using
+synthesis as thin films is strongly hindered by the lack of reliable theories,
+able to guide the design of new systems, through the understanding of the
+interface effects and of the way the substrate constraints are imposed to the
+material. The present paper analyses the energetic contributions at the
+interfaces, and proposes a model describing the microscopic mechanisms
+governing the interactions at an epitaxial interface between a manganite and
+another transition metal oxide in perovskite structure (as for instance $\rm
+SrTiO_3$). The model is checked against experimental results and literature
+analysis.",1105.0986v1
+2011-05-25,Interface study of FeMgOFe magnetic tunnel junctions using 3D Atom Probe,"A detailed interface study was conducted on a Fe/MgO/Fe system using laser
+assisted 3D atom probe. It exhibits an additional oxide formation at the second
+interface of the multilayer structure independent of laser wavelength, laser
+fluence and the thickness of the tunnel barrier. We have shown with the help of
+simulation that this phenomena is caused by the field evaporation of two layers
+having two different evaporation",1105.5099v1
+2011-12-04,A Superconducting Gap in an Insulator,"We present tunneling spectroscopy and transport measurements on disordered
+indium oxide films that reveal the existence of a superconducting gap in an
+insulating state. Two films on both sides of the disorder induced
+superconductor to insulator transition (SIT) show the same energy gap scale at
+low temperatures. This energy gap persists up to relatively high magnetic
+fields and is observed across the magnetoresistance peak typical of disordered
+superconductors. The results provide useful information for understanding the
+nature of the insulating state in the disorder induced SIT.",1112.0776v1
+2012-03-23,Charge dynamics of a single donor coupled to a few electrons quantum dot in silicon,"We study the charge transfer dynamics between a silicon quantum dot and an
+individual phosphorous donor using the conduction through the quantum dot as a
+probe for the donor ionization state. We use a silicon n-MOSFET (metal oxide
+field effect transistor) biased near threshold in the SET regime with two side
+gates to control both the device conductance and the donor charge. Temperature
+and magnetic field independent tunneling time is measured. We measure the
+statistics of the transfer of electrons observed when the ground state D0 of
+the donor is aligned with the SET states.",1203.5264v1
+2012-03-30,Determining the Curie temperature of La0.67Sr0.33MnO3 thin films,"When comparing a set of La0.67Sr0.33MnO3 (LSMO) samples, the Curie
+temperature (TC) of the samples is an important figure of merit for the sample
+quality. Therefore, a reliable method to determine TC is required. Here, a
+method based on the analysis of the magnetization loops is proposed.",1203.6730v1
+2012-09-12,Coherent spin control by electrical manipulation of the magnetic anisotropy,"High-spin paramagnetic manganese defects in polar piezoelectric zinc oxide
+exhibit a simple almost axial anisotropy and phase coherence times of the order
+of a millisecond at low temperatures. The anisotropy energy is tunable using an
+externally applied electric field. This can be used to control electrically the
+phase of spin superpositions and to drive spin transitions with resonant
+microwave electric fields.",1209.2745v2
+2012-10-17,Tunneling Spectroscopy of Graphene using Planar Pb Probes,"We show that evaporating lead (Pb) directly on graphene can create
+high-yield, high-quality tunnel probes, and we demonstrate high magnetic
+field/low temperature spectroscopy using these probes. Comparisons of Pb, Al
+and Ti/Au probes shows that after oxidation a well-formed self-limited tunnel
+barrier is created only between the Pb and the graphene. Tunneling spectroscopy
+using the Pb probes manifests energy-dependent features such as scattering
+resonances and localization behavior, and can thus be used to probe the
+microscopic electronics of graphene.",1210.4987v1
+2013-01-24,Pressure effects in hollow and solid iron oxide nanoparticles,"We report a study on the pressure response of the anisotropy energy of hollow
+and solid maghemite nanoparticles. The differences between the maghemite
+samples are understood in terms of size, magnetic anisotropy and shape of the
+particles. In particular, the differences between hollow and solid samples are
+due to the different shape of the nanoparticles and by comparing both pressure
+responses it is possible to conclude that the shell has a larger pressure
+response when compared to the core.",1301.5708v1
+2013-03-28,Superconductivity of Mg/MgO interface formed by shock-wave pressure,"A mixture of Mg and MgO has been subjected to a shock-wave pressure of 170
+kbar. The ac susceptibility measurements of the product has revealed a
+metastable superconductivity with Tc=30 K, characterized by glassy dynamics of
+the shielding currents below Tc. Comparison of the ac susceptibility and the dc
+magnetization measurements infers that the superconductivity arises within the
+interfacial layer formed between metallic Mg and its oxide due to the
+shock-wave treatment.",1303.7141v1
+2013-05-30,Origin of giant spin-lattice coupling and the suppression of ferroelectricity in EuTiO3 from first principles,"We elucidate the microscopic mechanism that causes a suppression of
+ferroelectricity and an enhancement of octahedral rotations in EuTiO3 from
+first principles. We find that the hybridization of the rare-earth Eu 4f states
+with the B-site Ti cation drives the system away from ferroelectricity. We also
+show that the magnetic order dependence of this hybridization is the dominant
+source of spin-phonon coupling in this material. Our results underline the
+importance of rare-earth f electrons on the lattice dynamics and stability of
+these transition metal oxides.",1305.7201v2
+2013-07-15,Cobalt spin state above the valence and spin-state transition in (Pr0.7Sm0.3)0.7Ca0.3CoO3,"(Pr0.7Sm0.3)0.7Ca0.3CoO3 belongs to a class of cobalt oxides undergoing a
+first-order transition (T* close to 90 K) associated to a coupled change in the
+valence and spin-state degrees of freedom. The Curie-Weiss regime present
+around room temperature (T >> T*) was analysed in detail to address the
+controversial issue of the cobalt spin states above the transition. This
+magnetic investigation indicates that the Co4+ are in an intermediate
+spin-state, while the Co3+ are in a mixed state combining low-spin and
+high-spin states. These results are discussed with respect to the literature on
+related compounds and recent results of x-ray absorption spectroscopy.",1307.3966v1
+2013-10-30,Geometrical origin of ferrimagnetism and superparamagnetism in Fe-based double perovskite multiferroics,"We show that a superstructure of antiferromagnetically interacting Fe$^{3+}$
+($S=5/2$) ions in double perovskites AFe$_{1/2}$M$_{1/2}$O$_{3}$ exhibits a
+ferrimagnetic ordering below $T_{fe} \approx 5.6J_1$ ($J_1/k_B \sim 50$~K),
+which is close to room temperature. Small clusters of the same structure
+exhibit a superparamagnetic behavior at $T \lesssim T_{fe}$. The possibility of
+formation of such clusters explains the room-temperature (superpara)magnetism
+in 3$d$-metal based oxides.",1310.8079v2
+2013-12-09,Nanoscale nuclear magnetic resonance with a 1.9-nm-deep nitrogen-vacancy sensor,"We present nanoscale NMR measurements performed with nitrogen-vacancy (NV)
+centers located down to about 2 nm from the diamond surface. NV centers were
+created by shallow ion implantation followed by a slow, nanometer-by-nanometer
+removal of diamond material using oxidative etching in air. The close proximity
+of NV centers to the surface yielded large 1H NMR signals of up to 3.4 uT-rms,
+corresponding to ~330 statistically polarized or ~10 fully polarized proton
+spins in a ~(1.8 nm)^3 detection volume.",1312.2394v2
+2015-02-10,Mechanisms and origin of multiferroicity,"Motivated by the potential applications of their intrinsic cross-coupling
+properties, the interest in multiferroic materials has constantly increased
+recently, leading to significant experimental and theoretical advancements.
+From the theoretical point of view, recent progresses have allowed to identify
+different mechanisms responsible for the appearence of ferroelectric
+polarization coexisting with -- and coupled to -- magnetic properties. This
+chapter aims at reviewing the fundamental mechanisms devised so far, mainly in
+transition-metal oxides, which lie at the origin of multiferroicity.",1502.02897v1
+2015-05-22,Oxygen-annealing effects on superconductivity in polycrystalline Fe1-xTe1-ySey,"Superconductivity in anti-PbO-type iron chalcogenides Fe1-xTe1-ySey (x = 0,
+0.1, y = 0.1 0.4) depends on the amount (x) of interstitial iron atoms located
+between the FeTe1-ySey layers. Non-superconducting samples of nominal
+Fe1.1Te1-ySey convert to superconductors with critical temperatures up to 14 K
+after annealing at 300{\deg}C in an oxygen atmosphere. The process is
+irreversible upon subsequent hydrogen annealing. Magnetic measurements are
+consistent with the formation of iron oxides suggesting that oxygen annealing
+preferably extracts interstitial iron from Fe1-xTe1-ySey which interfere with
+superconductivity.",1505.06066v1
+2015-10-08,Nematic ordering in pyrochlore antiferromagnets: high-field phase of chromium spinel oxides,"Motivated by recent observation of a new high field phase near saturation in
+chromium spinels $A$Cr$_2$O$_4$ ($A=$ Zn, Cd, Hg), we study the $S = 3/2$
+pyrochlore Heisenberg antiferromagnet with biquadratic interactions. Magnon
+instability analysis at the saturation field reveals that a very small
+biquadratic interaction can induce magnon pairing in pyrochlore
+antiferromagnets, which leads to the emergence of a ferro-quadrupolar phase, or
+equivalently a spin nematic phase, below the saturation field. We present the
+magnetic phase diagram in an applied field, studying both $S=3/2$ and $S=1$
+spin systems. The relevance of our result to chromium spinels is discussed.",1510.02373v1
+2015-10-28,Strong correlations generically protect d-wave superconductivity against disorder,"We address the question of why strongly correlated d-wave superconductors,
+such as the cuprates, prove to be surprisingly robust against the introduction
+of non-magnetic impurities. We show that, very generally, both the
+pair-breaking and the normal state transport scattering rates are significantly
+suppressed by strong correlations effects arising in the proximity to a Mott
+insulating state. We also show that the correlation-renormalized scattering
+amplitude is generically enhanced in the forward direction, an effect which was
+previously often ascribed to the specific scattering by charged impurities
+outside the copper-oxide planes.",1510.08152v2
+2017-02-01,Structural characterization of magnetoferritin,"The physicochemical characterization of the magnetoferritin biomacromolecule
+in terms of morphology, structural and magnetic properties shows that iron
+oxides can be efficiently loaded into apoferritin molecules, preserving their
+native biocompatible structure and affecting the morphology of the protein
+shell.",1702.00138v1
+2017-03-20,Why only hole conductors can be superconductors,"The conventional theory of superconductivity says that charge carriers in a
+metal that becomes superconducting can be either electrons or holes. I argue
+that this is incorrect. In order to satisfy conservation of mechanical momentum
+and of entropy of the universe in the superconductor to normal transition in
+the presence of a magnetic field it is necessary that the normal state charge
+carriers are holes. I will also review the empirical evidence in favor of the
+hypothesis that all superconductors are hole superconductors, and discuss the
+implications of this for the search for higher $T_c$ superconductors.",1703.09777v1
+2018-04-04,Theoretical prediction of two-dimensional CrOF sheet as a ferromagnetic semiconductor or a half-metal,"Two-dimensional chromium oxide fluoride CrOF sheet was studied based on
+density functional theory. The investigation indicates that the CrOF sheet is
+an intrinsic ferromagnetic semiconductor. The calculated low cleavage energy
+implies that the ferromagnetic semiconductor can be exfoliated from its bulk
+form. The corresponding Curie temperature is 150 K. In particular, the Curie
+temperature increases up to 410 K under hole doping and the CrOF sheet becomes
+a half-metal. The versatile electronic and magnetic properties indicate that
+the two-dimensional CrOF sheet can be a promising candidate for next-generation
+spintronic devices.",1804.01621v1
+2013-08-26,"Enhancement of antiferromagnetic interaction and transition temperature in M3TeO6 systems (M = Mn, Co, Ni, Cu)","Several M3 TeO6 (M = Mn, Co, Ni, Cu) oxides order antiferromagnetically at
+low temperatures (near or below 60 K), while displaying interesting dielectric
+properties at high temperatures (ferroelectricity below 1000 K in M = Ni case).
+We have investigated and analyzed the structural and magnetic properties of
+Mn-doped Co3 TeO6 and Ni3 TeO6, which order antiferromagnetically at
+temperatures higher than their undoped counterparts.",1308.5505v1
+2016-11-17,Colossal enhancement of electrical conductivity in Y2Ir2O7 nanoparticles,"We present a comparative study of the magnetic and electrical properties of
+polycrystalline and nanocrystalline Y2Ir2O7, the latter prepared using a new
+chemical route. We find that reduction in particle size leads to enhanced
+ferromagnetism and orders of magnitude enhancement of electrical conductivity
+in the nanocrystalline sample. Based on x ray photoelectron spectroscopy and x
+ray absorption near edge structure spectroscopy results, the phenomenon is
+attributed to the increased fraction of pentavalent oxidation state of Iridium
+and the resulting increase in double exchange interaction along with the
+weakening of spin orbit coupling strength in the nanocrystalline sample
+compared to the bulk.",1611.05661v1
+2018-05-02,"Accurate Cathode Properties of LiNiO2, LiCoO2, and LiMnO2 Using the SCAN Meta-GGA Density Functional","Layered lithium intercalating transition metal (TM) oxides are promising
+cathode materials for Li-ion batteries. Here we scrutinize the recently
+developed strongly constrained and appropriately normed (SCAN) density
+functional method to study structural, magnetic and electrochemical properties
+of prototype cathode materials LiNiO2, LiCoO2, and LiMnO2 at different
+Li-intercalation limits. We show that SCAN outperforms earlier popular
+functional combinations, providing results in considerably better agreement
+with experiment without use of Hubbard parameters, and dispersion corrections
+are found to have a small effect. In particular, SCAN provides a good
+description of the electronic structures, electron densities, band gaps,
+predicted cell parameters, and voltage profiles.",1805.00642v1
+2008-07-29,Thermally activated Peierls dimerization in ferromagnetic spin chains,"We demonstrate that a Peierls dimerization can occur in ferromagnetic spin
+chains activated by thermal fluctuations. The dimer order parameter and
+entanglement measures are studied as functions of the modulation of the
+magnetic exchange interaction and temperature, using a spin-wave theory and the
+density-matrix renormalization group. We discuss the case where a periodic
+modulation is caused by spin-phonon coupling and the case where electronic
+states effectively induce such a modulation. The importance of the latter for a
+number of transition metal oxides is highlighted.",0807.4693v1
+2017-12-28,A survey of TiOλ567 nm absorption in solar-type stars,"Molecular absorption bands are estimators of stellar activity and spot cycles
+on magnetically active stars. We have previously introduced a new color index
+that compare absorption strength of the titanium oxide (TiO) at 567 nm with
+nearby continuum. In this paper we implement this index to measure long-term
+activity variations and the statistical properties of the index in a sample of
+302 solar-type stars from the HARPS planet search program. The results indicate
+a pattern of change in star's activity, covers a range of periods from 2 years
+up to 17 years.",1712.09882v1
+2018-01-25,Optical frequency comb Faraday rotation spectroscopy,"We demonstrate optical frequency comb Faraday rotation spectroscopy (OFC-FRS)
+for broadband interference-free detection of paramagnetic species. The system
+is based on a femtosecond doubly resonant optical parametric oscillator and a
+fast-scanning Fourier transform spectrometer (FTS). The sample is placed in a
+DC magnetic field parallel to the light propagation. Efficient background
+suppression is implemented via switching the direction of the field on
+consecutive FTS scans and subtracting the consecutive spectra, which enables
+long term averaging. In this first demonstration, we measure the entire Q- and
+R-branches of the fundamental band of nitric oxide in the 5.2-5.4 {\mu}m range
+and achieve good agreement with a theoretical model.",1801.08399v1
+2019-10-31,Valence bond phases of herbertsmithite and related copper kagome materials,"Recent evidence from magnetic torque, electron spin resonance, and second
+harmonic generation indicate that the prototypical quantum spin liquid
+candidate, herbertsmithite, has a symmetry lower than its x-ray refined
+trigonal space group. Here, we consider known and possible distortions of this
+mineral class, along with related copper kagome oxides and fluorides, relate
+these to possible valence bond patterns, and comment on their relevance to the
+physics of these interesting materials.",1910.14196v2
+2000-06-02,Dzyaloshinskii-Moriya interaction in NaV$_2$O$_5$: a microscopic study,"We present a unified account of magnetic exchange and Raman scattering in the
+quasi-one-dimensional transition-metal oxide NaV$_2$O$_5$. Based on a
+cluster-model approach explicit expressions for the exchange integral and the
+Raman-operator are given. It is demonstrated that a combination of the
+electronic-structure and the Dzyaloshinskii-Moriya interaction, allowed by
+symmetry in this material, are responsible for the finite Raman cross-section
+giving rise to both, one- and two-magnon scattering amplitudes.",0006036v1
+2018-06-19,Consequences of the CMR effect on EELS in TEM,"Double perovskite oxides have gained in importance and exhibit negative
+magnetoresistance, which is known as colossal magnetoresistance (CMR) effect.
+Using a La$_2$CoMnO$_6$ (LCM) thin film we prove that the physical consequences
+of the CMR effect do also influence the electron energy loss spectrometry
+(EELS) signal. We observe a change of the band gap at low energy losses and are
+able to study the magnetisation with chemical sensitivity by employing energy
+loss magnetic chiral dichroism (EMCD) below the Curie temperature T$_C$ where
+the CMR effect becomes significant.",1806.07118v1
+2018-12-21,Electric field tuning of the anomalous Hall effect at oxide interfaces,"We show that the anomalous Hall effect (AHE) at a magnetic interface with
+strong spin-orbit coupling can be tuned with an external electric field. By
+altering the strength of the inversion symmetry breaking, the electric field
+changes the Rashba interaction, which in turn modifies the magnitude of the
+Berry curvature, the central quantity in determining the anomalous Hall
+conductivity (AHC). The effect is illustrated with a square lattice model,
+which yields a quadratic dependence of the AHC for small electric fields.
+Explicit density-functional calculations were performed for the recently grown
+iridate interface, viz., the (SrIrO$_3$)$_1$/(SrMnO$_3$)$_1$ (001) structure,
+both with and without an electric field. The effect may be potentially useful
+in spintronics applications.",1812.08950v1
+2023-12-07,Oxidation tuning of ferroic transitions in Gd$_2$C monolayer,"Tuning of ferroic phases provides great opportunities for material
+functionalities, especially in two-dimensional materials. Here, a $4f$
+rare-earth carbide Gd$_2$C monolayer is predicted to be ferromagnetic metal
+with large magnetization, inherited from its bulk property. Based on
+first-principles calculations, we propose a strategy that the surface
+passivation can effectively tune its ferroicity, namely switching among
+ferromagnetic, antiferromagnetic, and ferroelectric phases. Metal-insulator
+transition also occurs accompanying these ferroic transitions. Our calculation
+also suggests that the magneto-optic Kerr effect and second harmonic generation
+are effective methods to monitor these phase transitions.",2312.04011v1
+1993-07-19,Evolution of Magnetic Properties of Lightly Doped Copper Oxides,"We study how doping destroys the AF order in the layered cuprates within the
+framework of the charge--transfer insulator concept. We use the criterion of
+stability of the AF background to show that the stability problem is one of the
+main issues in any correspondence between results for the $t-J$ model and, say,
+the three--band model for the lightly--doped layered oxides. Provided a
+phenomenological conduction band is chosen to satisfy the criterion of
+stability, a detailed picture of how dopants influence the spin wave spectrum
+at $T=0$ is presented. The critical concentration $x_c$ for the destruction of
+the AF long range order is due to the Cherenkov effect when the Fermi velocity
+first exceeds the spin wave velocity. We then discuss the overall spectrum of
+spin excitations and find that the spin wave attenuation for $x < x_c$, $T=0$
+due to Landau damping appears in the range of magnon momenta $k(x) = 2 m^* s
+\pm \alpha \sqrt{x}$. We also argue that in the presence of superconductivity,
+the Cherenkov effect is eliminated due to the gap in the spectrum. This may
+restore the role of the AF fluctuations as the main source of dissipation at
+the lowest temperatures.",9307040v1
+1997-12-15,Spin Tunneling in Conducting Oxides,"Direct tunneling in ferromagnetic junctions is compared with
+impurity-assisted, surface state assisted, and inelastic contributions to a
+tunneling magnetoresistance (TMR). Theoretically calculated direct tunneling in
+iron group systems leads to about a 30% change in resistance, which is close to
+experimentally observed values. It is shown that the larger observed values of
+the TMR might be a result of tunneling involving surface polarized states. We
+find that tunneling via resonant defect states in the barrier radically
+decreases the TMR (down to 4% with Fe-based electrodes), and a resonant tunnel
+diode structure would give a TMR of about 8%. With regards to inelastic
+tunneling, magnons and phonons exhibit opposite effects: one-magnon emission
+generally results in spin mixing and, consequently, reduces the TMR, whereas
+phonons are shown to enhance the TMR. The inclusion of both magnons and phonons
+reasonably explains an unusual bias dependence of the TMR.
+  The model presented here is applied qualitatively to half-metallics with 100%
+spin polarization, where one-magnon processes are suppressed and the change in
+resistance in the absence of spin-mixing on impurities may be arbitrarily
+large. Even in the case of imperfect magnetic configurations, the resistance
+change can be a few 1000 percent. Examples of half-metallic systems are
+CrO$_2$/TiO$_2$ and CrO$_2$/RuO$_2$, and an account of their peculiar band
+structures is presented. The implications and relation of these systems to CMR
+materials which are nearly half-metallic, are discussed.",9712170v2
+2001-11-01,"To the problem of electron-phonon interaction and ""d-wave pairing"" in high-Tc oxides","It is supported a recent proposal by Maksimov that electron-phonon
+interaction (EPI) (Gruneisen-Bloch formulae) determines the linearity of
+temperature dependence of resistivity for both HTSC-cuprates and most of metals
+at T near above 0.2 of their characteristic Debye temperature (normal state for
+HTSC). However, it is emphasized here that in this T-region the resistivity is
+not proportional to T but is only linear in T. This fact indicates to
+T-independent contribution to normal-state resistivity in HTSC-cuprates
+(magnetic contribution, in our treatment) which behavior, in its turn,
+indicates to possible magnetic (SDW-like) phase transition before SC transition
+in HTSC-system. SDW-gap (measured as pseudogap with d-wave symmetry, in our
+treatment) is formed at the symmetrical parts of the Fermi surface above Tc and
+persists in SC state. The magnitude of SDW-gap is essentially larger than that
+for SC-gap. So, SDW formed can mimic d-wave symmetry of the order parameter
+measured below Tc (which is now attributed to d-wave pairing). On the other
+hand, since the Gruneisen-Bloch curve appears to be (in approach used) a
+geometric locus for the Tc(onset)(H) (as in LTSC) this fact evidents about
+EPI-nature (BCS) of SC transition (s-wave) in high-Tc oxides. The proposal to
+increase Tc using above (SDW/CDW/SC) model (and possible realization) is
+presented.",0111015v1
+2002-02-14,Spin and Orbital States and Their Phase Transitions of the Perovskite-Type Ti Oxides: Weak coupling Approach,"The magnetic phase diagram of the perovskite-type Ti oxides as a function of
+the GdFeO3-type distortion is examined by using the Hartree-Fock analysis of a
+multiband d-p Hamiltonian from a viewpoint of competitions of the spin-orbit
+interaction, the Jahn-Teller (JT) level-splitting and spin-orbital
+superexchange interactions. Near the antiferromagnetic (AFM)-to-ferromagnetic
+(FM) phase boundary, A-type AFM [AFM(A)] and FM states accompanied by a certain
+type of orbital ordering are lowered in energy at large JT distortion, which is
+in agreement with the previous strong coupling study. With increasing the
+GdFeO3-type distortion, their phase transition occurs. Through this magnetic
+phase transition, the orbital state hardly changes, which induces nearly
+continuous change in the spin coupling along the c-axis from negative to
+positive. The resultant strong two-dimensionality in the spin coupling near the
+phase boundary is attributed to the strong suppression of T_N and T_C, which is
+experimentally observed. On the other hand, at small GdFeO3-type without JT
+distortions, which correspond to LaTiO3, the most stable solution is not G-type
+AFM [AFM(G)] but FM. Although the spin-orbit interaction has been considered to
+be relevant at the small or no JT distortion of LaTiO3 in the literature, our
+analysis indicates that the spin-orbit interaction is irrelevant to the AFM(G)
+state in LaTiO3 and superexchange-type interaction dominates. On the basis of
+further investigations on the nature of this FM state and other solutions, this
+discrepancy is discussed in detail.",0202242v1
+2003-09-10,First principles electronic structure of spinel LiCr2O4: A possible half-metal?,"We have employed first-principles electronic structure calculations to
+examine the hypothetical (but plausible) oxide spinel, LiCr2O4 with the d^{2.5}
+electronic configuration. The cell (cubic) and internal (oxygen position)
+structural parameters have been obtained for this compound through structural
+relaxation in the first-principles framework. Within the one-electron band
+picture, we find that LiCr2O4 is magnetic, and a candidate half-metal. The
+electronic structure is substantially different from the closely related and
+well known rutile half-metal CrO2. In particular, we find a smaller conduction
+band width in the spinel compound, perhaps as a result of the distinct topology
+of the spinel crystal structure, and the reduced oxidation state. The magnetism
+and half-metallicity of LiCr2O4 has been mapped in the parameter space of its
+cubic crystal structure. Comparisons with superconducting LiTi2O4 (d^{0.5}),
+heavy-fermion LiV2O4 (d^{1.5}) and charge-ordering LiMn2O4 (d^{3.5}) suggest
+the effectiveness of a nearly-rigid band picture involving simple shifts of the
+position of E_F in these very different materials. Comparisons are also made
+with the electronic structure of ZnV2O4 (d^{2}), a correlated insulator that
+undergoes a structural and antiferromagnetic phase transition.",0309246v2
+2004-07-27,Magnetic field dependence of low temperature specific heat of spinel oxide superconductor LiTi_2O_4,"Magnetic field dependence of low temperature specific heat of spinel oxide
+superconductor LiTi_2O_4 has been elaborately investigated. In the normal
+state, the obtained electronic coefficient of specific heat gamma_n = 19.15
+mJ/mol K2, the Debye temperature is 657 K and some other parameters are
+compared with those reported earlier. The superconducting transition at Tc ~
+11.4 K is very sharp (DeltaTc ~ 0.3 K) and the estimated delataC/gamma_nTc is ~
+1.78. In the superconducting state, the best fit of data leads to the
+electronic specific heat C_es/Gamma_nTc = 9.87 exp (-1.58 Tc/T) without field
+and gamma(H) ~ H^0.95 with fields. In addition, Hc2(0) ~ 11.7 T, Hc(0) ~ 0.32
+T, xi_GL(0) ~ 5.5 nm, lambda_GL(0) ~ 160 nm, and Hc1(0) ~ 26 mT are estimated
+from Werthamer-Helfand-Hohenberg (WHH) theory or other relevant relations. All
+results from the present study indicate that LiTi2O4 can be well described by a
+typical type-II, BCS-like, moderate coupling, and fully gapped superconductor
+in the dirty limit. It is further suggested that LiTi2O4 is a moderately
+electron-electron correlated system.",0407695v1
+2005-01-11,Two dimensionality in quasi one-dimensional cobalt oxides,"By means of muon spin rotation and relaxation ($\mu^+$SR) techniques, we have
+investigated the magnetism of quasi one-dimensional (1D) cobalt oxides
+$AE_{n+2}$Co$_{n+1}$O$_{3n+3}$ ($AE$=Ca, Sr and Ba, $n$=1, 2, 3, 5 and
+$\infty$), in which the 1D CoO$_3$ chain is surrounded by six equally spaced
+chains forming a triangular lattice in the $ab$-plane, using polycrystalline
+samples, from room temperature down to 1.8 K. For the compounds with $n$=1 - 5,
+transverse field $\mu^+$SR experiments showed the existence of a magnetic
+transition below $\sim$100 K. The onset temperature of the transition ($T_{\rm
+c}^{\rm on}$) was found to decrease with $n$; from 100 K for $n$=1 to 60 K for
+$n$=5. A damped muon spin oscillation was observed only in the sample with
+$n$=1 (Ca$_3$Co$_2$O$_6$), whereas only a fast relaxation obtained even at 1.8
+K in the other three samples. In combination with the results of susceptibility
+measurements, this indicates that a two-dimensional short-range
+antiferromagnetic (AF) order appears below $T_{\rm c}^{\rm on}$ for all
+compounds with $n$=1 - 5; but quasi-static long-range AF order formed only in
+Ca$_3$Co$_2$O$_6$, below 25 K. For BaCoO$_3$ ($n$=$\infty$), as $T$ decreased
+from 300 K, 1D ferromagnetic (F) order appeared below 53 K, and a sharp 2D AF
+transition occurred at 15 K.",0501232v1
+2005-06-27,Strong-coupling theory of high-temperature superconductivity and colossal magnetoresistance,"We argue that the extension of the BCS theory to the strong-coupling regime
+describes the high-temperature superconductivity of cuprates and the colossal
+magnetoresistance (CMR) of ferromagnetic oxides if the phonon dressing of
+carriers and strong attractive correlations are taken into account. The
+long-range Froehlich electron-phonon interaction has been identified as the
+most essential in cuprates providing ""superlight"" lattice polarons and
+bipolarons. Here some kinetic, magnetic, and more recent thermomagnetic normal
+state measurements are interpreted in the framework of the strong-coupling
+theory, including the Nernst effect and normal state diamagnetism. Remarkably,
+a similar strong-coupling approach offers a simple explanation of CMR in
+ferromagnetic oxides. The pairing of oxygen holes into heavy bipolarons in the
+paramagnetic phase and their magnetic pair-breaking in the ferromagnetic phase
+account for the first-order ferromagnetic phase transition, CMR, isotope
+effects, and pseudogaps in doped manganites. Here we propose an explanation of
+the phase coexistence and describe the shape of resistivity of manganites near
+the transition in the framework of the strong-coupling approach.",0506706v3
+2005-08-31,Spinel ferrites: old materials bring new opportunities for spintronics,"Over the past few years, intensive studies of ultrathin epitaxial films of
+perovskite oxides have often revealed exciting properties like giant
+magnetoresistive tunnelling and electric field effects. Spinel oxides appear as
+even more versatile due to their more complex structure and the resulting many
+degrees of freedom. Here we show that the epitaxial growth of nanometric
+NiFe2O4 films onto perovskite substrates allows the stabilization of novel
+ferrite phases with properties dramatically differing from bulk ones. Indeed,
+NiFe2O4 films few nanometres thick have a saturation magnetization at least
+twice that of the bulk compound and their resistivity can be tuned by orders of
+magnitude, depending on the growth conditions. By integrating such thin NiFe2O4
+layers into spin-dependent tunnelling heterostructures, we demonstrate that
+this versatile material can be useful for spintronics, either as a conductive
+electrode in magnetic tunnel junctions or as a spin-filtering insulating
+barrier in the little explored type of tunnel junction called spin-filter. Our
+findings are thus opening the way for the realisation of monolithic spintronics
+architectures integrating several layers of a single material, where the layers
+are functionalised in a controlled manner.",0508764v1
+2005-10-03,New Misfit-Layered Cobalt Oxide (CaOH)1.14CoO2,"We found a new cobalt oxide (CaOH)1.14CoO2 by utilizing the high-pressure
+technique. X-ray and electron diffraction studies revealed that the compound
+has layer structure which consists of CdI2-type CoO2 layers and rock-salt-type
+double CaOH atomic layers. The two subcells have incommensurate periodicity
+along the a-axis, resulting in modulated crystal structure due to the
+inter-subcell interaction. The structural modulation affects carrier conduction
+through the potential randomness. We found that the two-dimensional (2-D)
+variable-range hopping (VRH) regime with hole conduction is dominant at low
+temperature for this compound, and that the conduction mechanism undergoes
+crossover from the 2-D VRH regime to thermal activation-energy type one with
+increasing temperature. Based on the experimental results of resistivity,
+thermoelectric power, magnetic susceptibility and specific heat measurements,
+we suggested a possible electronic-band structure model to explain these
+results. The cobalt t2g-derivative band crosses Fermi energy level near the
+band edge, yielding small finite density of localized states at the Fermi level
+in the band. The observed resistivity, Seebeck coefficient, large Pauli
+paramagnetic component in the magnetic susceptibility and comparatively small
+Sommerfeld constant in the specific heat are principally attributed to the
+holes in the t2g-derivative band. We estimated the Wilson ratio to be about
+2.8, suggesting the strong electron correlation realized in this compound.",0510031v1
+2006-07-05,Resonance in the electron-doped high-Tc superconductor Pr0.88LaCe0.12CuO(4-delta),"In conventional superconductors, the interaction that pairs the electrons to
+form the superconducting state is mediated by lattice vibrations (phonons). In
+high-transition temperature (high-Tc) copper oxides, it is generally believed
+that magnetic excitations play a fundamental role in the superconducting
+mechanism because superconductivity occurs when mobile 'electrons' or 'holes'
+are doped into the antiferromagnetic parent compounds. Indeed, a sharp magnetic
+excitation termed ""resonance"" has been observed by neutron scattering in a
+number of hole-doped materials. The resonance is intimately related to
+superconductivity, and its interaction with charged quasi-particles observed by
+photoemission, optical conductivity, and tunneling suggests that it plays a
+similar role as phonons in conventional superconductors. However, the relevance
+of the resonance to high-Tc superconductivity has been in doubt because so far
+it has been found only in hole-doped materials. Here we report the discovery of
+the resonance in electron-doped superconducting Pr0.88LaCe0.12CuO(4-delta) (Tc
+= 24 K). We find that the resonance energy (Er) is proportional to Tc via Er =
+5.8kBTc (kB is the Boltzmann's constant) for all high-Tc superconductors
+irrespective of electron- or hole-doping (Fig. 1e). Our results demonstrate
+that the resonance is a fundamental property of the superconducting copper
+oxides and therefore must play an essential role in the mechanism of
+superconductivity.",0607134v1
+2006-10-07,"Synthesis of nanocrystalline (Co,Ni)Al2O4 spinel powder by mechanical milling of quasicrystalline material","The (Co,Ni)Al2O4 is an aluminum transition metals oxide which falls into the
+category of aluminate spinels. The synthesis of nano-crystalline spinels has
+been investigated extensively due to their potential applications such as a
+high-density magnetic recording, microwave devices magnetic fluids, ceramic
+pigment as well as a heterogeneous catalytic material. In the present study,
+attempts have been made to synthesise the nano-crystalline (Co,Ni)Al2O4 spinel
+powders by ball milling and subsequent annealing. An alloy of Al70 Ni15 Co15,
+exhibiting the formation of a complex intermetallic compound known as decagonal
+quasicrystals in the as-solidified condition, is selected as the starting
+material for mechanical milling. It is interesting to note that this alloy is
+close to the stoichiometry of aluminum and transition metal atoms required to
+form of the aluminate spinel. The milling was carried out in an attritor mill
+at 400 rpm for 40 hours with ball to powder ratio of 20:1 in hexane medium and
+the annealing was performed for 10, 20 and 40 h at 600 0 C in air in side the
+furnace in order to oxidize the decagonal phase and finally to form the spinel
+structures. The X-ray diffraction (XRD) and transmission electron microscopy
+(TEM) confirmed the formation of nano-sized decagonal phase after milling and
+then (Co,Ni)Al2O4 spinel type structure from the nano-size decagonal phase
+during annealing. The average crystallite size has been found to be ~40 nm by
+XRD and TEM studies, the lattice strain is 0.6 %, and the lattice parameter is
+8.0756 A . The ferromagnetic behaviour is also observed in the milled and the
+annealed samples.",0610203v1
+2007-08-27,The nanoscale phase separation in hole-doped manganites,"A macroscopic phase separation, in which ferromagnetic clusters are observed
+in an insulating matrix, is sometimes observed, and believed to be essential to
+the colossal magnetoresistive (CMR) properties of manganese oxides. The
+application of a magnetic field may indeed trigger large magnetoresistance
+effects due to the percolation between clusters allowing the movement of the
+charge carriers. However, this macroscopic phase separation is mainly related
+to extrinsic defects or impurities, which hinder the long-ranged charge-orbital
+order of the system. We show in the present article that rather than the
+macroscopic phase separation, an homogeneous short-ranged charge-orbital order
+accompanied by a spin glass state occurs, as an intrinsic result of the
+uniformity of the random potential perturbation induced by the solid solution
+of the cations on the $A$-sites of the structure of these materials. Hence the
+phase separation does occur, but in a more subtle and interesting nanoscopic
+form, here referred as ``homogeneous''. Remarkably, this ``nanoscale phase
+separation'' alone is able to bring forth the colossal magnetoresistance in the
+perovskite manganites, and is potentially relevant to a wide variety of other
+magnetic and/or electrical properties of manganites, as well as many other
+transition metal oxides, in bulk or thin film form as we exemplify throughout
+the article.",0708.3524v2
+2009-03-16,Spin Waves and Magnetic Exchange Interactions in CaFe2As2,"Antiferromagnetism is relevant to high temperature (high-Tc)
+superconductivity because copper oxide and iron arsenide high-Tc
+superconductors arise from electron- or hole-doping of their antiferromagnetic
+(AF) ordered parent compounds. There are two broad classes of explanation for
+the phenomenon of antiferromagnetism: in the local moment picture, appropriate
+for the insulating copper oxides, AF interactions are well described by a
+Heisenberg Hamiltonian; while in the itinerant model, suitable for metallic
+chromium, AF order arises from quasiparticle excitations of a nested Fermi
+surface. There has been contradictory evidence regarding the microscopic origin
+of the AF order in iron arsenide materials, with some favoring a localized
+picture while others supporting an itinerant point of view. More importantly,
+there has not even been agreement about the simplest effective ground state
+Hamiltonian necessary to describe the AF order. Here we report inelastic
+neutron scattering mapping of spin-wave excitations in CaFe2As2, a parent
+compound of the iron arsenide family of superconductors. We find that the spin
+waves in the entire Brillouin zone can be described by an effective
+three-dimensional local moment Heisenberg Hamiltonian, but the large in-plane
+anisotropy cannot. Therefore, magnetism in the parent compounds of iron
+arsenide superconductors is neither purely local nor purely itinerant; rather
+it is a complicated mix of the two.",0903.2686v1
+2012-08-16,Strain-Induced Spin States in Atomically Ordered Cobaltites,"Epitaxial strain imposed in complex oxide thin films by heteroepitaxy is
+recognized as a powerful tool for identifying new properties and exploring the
+vast potential of materials performance. A particular example is LaCoO3, a zero
+spin, nonmagnetic material in the bulk, whose strong ferromagnetism in a thin
+film remains enigmatic despite a decade of intense research. Here, we use
+scanning transmission electron microscopy complemented by X-ray and optical
+spectroscopy to study LaCoO3 epitaxial thin films under different strain
+states. We observed an unconventional strain relaxation behavior resulting in
+stripe-like, lattice modulated patterns, which did not involve uncontrolled
+misfit dislocations or other defects. The modulation entails the formation of
+ferromagnetically ordered sheets comprising intermediate or high spin Co3+,
+thus offering an unambiguous description for the exotic magnetism found in
+epitaxially strained LaCoO3 films. This observation provides a novel route to
+tailoring the electronic and magnetic properties of functional oxide
+heterostructures.",1208.3479v1
+2012-11-06,Inhomogeneous superconductivity induced by interstitial Fe deintercalation in oxidizing-agent-annealed and HNO3-treated Fe1+y(Te1-xSex),"We have systematically investigated the annealing effect on the
+superconductivity of iron chalcogenide Fe1+y(Te1-xSex). The atmospheres used
+for annealing include O2, N2, I2 vapor, air and vacuum. We observed that
+annealing in O2, I2 and air could enhance superconductivity for the underdoped
+samples, consistent with the results reported in literatures. Interestingly, we
+found that annealing in N2 also leads to superconductivity enhancement, similar
+to the annealing effects of O2, I2 and air. However, vacuum annealing does not
+enhance superconductivity, which indicates that the enhanced superconductivity
+in O2-, N2-, I2- and air-annealed samples is not due to improved homogeneity.
+In addition, we have treated the underdoped samples with nitric acid, which is
+found to enhance superconductivity as well. Our analyses of these results
+support the argument that the superconductivity enhancement, caused either by
+annealing or nitric acid treatment, originates from the variation of
+interstitial Fe. The interstitial Fe, which is destructive to superconducting
+pairing, can be reduced by annealing in oxidation agents or nitric acid
+treatment. We also find that although N2-, O2- and air-annealed samples exhibit
+strong superconducting diamagnetism with -4pichi ~1 (chi, dc magnetic
+susceptibility) for some samples, their actual superconducting volume fraction
+probed by specific heat is low, ranging from 10% to 30% for 0.09 < x < 0.3,
+indicating that the superconductivity suppression remains significant even in
+annealed samples. The strong diamagnetism is associated with the
+superconducting shielding effect on the non-superconducting phase. We have also
+established the phase diagram of the annealed samples and compared it with that
+of the as-grown samples. The effect of annealing on the interplay between
+magnetism and superconductivity is discussed.",1211.1292v1
+2013-11-26,Spatial Correlations and the Insulating Phase of the High-$T_c$ Cuprates: Insights from a Configuration-Interaction-Based Solver for Dynamical Mean Field Theory,"A recently proposed configuration-interaction based impurity solver is used
+in combination with the single-site and four-site cluster dynamical mean field
+approximations to investigate the three-band copper oxide model believed to
+describe the electronic structure of high transition temperature copper-oxide
+superconductors. Use of the configuration interaction solver enables
+verification of the convergence of results with respect to the number of bath
+orbitals. The spatial correlations included in the cluster approximation
+substantially shift the metal-insulator phase boundary relative to the
+prediction of the single-site approximation and increase the predicted energy
+gap of the insulating phase by about 1 eV above the single-site result. Vertex
+corrections occurring in the four-site approximation act to dramatically
+increase the value of the optical conductivity near the gap edge, resulting in
+a better agreement with the data. The calculations reveal two distinct
+correlated insulating states: the `magnetically correlated insulator', in which
+nontrivial intersite correlations play an essential role in stabilizing the
+insulating state, and the strongly correlated insulator, in which local physics
+suffices. Comparison of the calculations to the data place the cuprates in the
+magnetically correlated Mott insulator regime.",1311.6819v3
+2013-12-28,Kitaev interactions between j=1/2 moments in honeycomb Na2IrO3 are large and ferromagnetic: insights from ab initio quantum chemistry calculations,"Na$_2$IrO$_3$, a honeycomb 5$d^5$ oxide, has been recently identified as a
+potential realization of the Kitaev spin lattice. The basic feature of this
+spin model is that for each of the three metal-metal links emerging out of a
+metal site, the Kitaev interaction connects only spin components perpendicular
+to the plaquette defined by the magnetic ions and two bridging ligands. The
+fact that reciprocally orthogonal spin components are coupled along the three
+different links leads to strong frustration effects and nontrivial physics.
+While the experiments indicate zigzag antiferromagnetic order in Na$_2$IrO$_3$,
+the signs and relative strengths of the Kitaev and Heisenberg interactions are
+still under debate. Herein we report results of ab initio many-body electronic
+structure calculations and establish that the nearest-neighbor exchange is
+strongly anisotropic with a dominant ferromagnetic Kitaev part, whereas the
+Heisenberg contribution is significantly weaker and antiferromagnetic. The
+calculations further reveal a strong sensitivity to tiny structural details
+such as the bond angles. In addition to the large spin-orbit interactions, this
+strong dependence on distortions of the Ir$_2$O$_2$ plaquettes singles out the
+honeycomb 5$d^5$ oxides as a new playground for the realization of
+unconventional magnetic ground states and excitations in extended systems.",1312.7437v2
+2014-04-28,Bandgap Controlling of the Oxygen-Vacancy-Induced Two-Dimensional Electron Gas in SrTiO3,"We report very large bandgap enhancement in SrTiO3 (STO) films (fabricated by
+pulsed laser deposition below 800 {\deg}C), which can be up to 20% greater than
+the bulk value, depending on the deposition temperature. The origin is
+comprehensively investigated and finally attributed to Sr/Ti antisite point
+defects, supported by density functional theory calculations. More importantly,
+the bandgap enhancement can be utilized to tailor the electronic and magnetic
+phases of the two-dimensional electron gas (2DEG) in STO-based interface
+systems. For example, the oxygen-vacancy-induced 2DEG (2DEG-V) at the interface
+between amorphous LaAlO3 and STO films is more localized and the ferromagnetic
+order in the STO-film-based 2DEG-V can be clearly seen from low-temperature
+magnetotransport measurements. This opens an attractive path to tailor
+electronic, magnetic and optical properties of STO-based oxide interface
+systems under intensive focus in the oxide electronics community. Meanwhile,
+our study provides key insight into the origin of the fundamental issue that
+STO films are difficult to be doped into the fully metallic state by oxygen
+vacancies.",1404.6863v2
+2015-04-30,Self Duality and a possible Hall-insulator phase near the superconductor-to-insulator transition in two-dimensional indium-oxide films,"We combine measurements of the longitudinal ($\rho_{xx}$) and Hall
+($\rho_{xy}$) resistivities of disordered two dimensional amorphous
+indium-oxide films to study the magnetic-field tuned superconductor to
+insulator transition (H-SIT) in the $T \to 0$ limit. At the critical field,
+$H_c$, the full resistivity tensor is $T$ independent with $\rho_{xx}(H_c) =
+h/4e^2$ and $\rho_{xy}(H_c)=0$ within experimental uncertainty in all films
+(i.e. these appear to be ""universal"" values), this is strongly suggestive that
+there is a particle-vortex self-duality at $H=H_c$. The transition separates
+the (presumably) superconducting state at $H<H_c$ from a ""Hall-insulator"" phase
+in which $\rho_{xx}\to \infty$ as $T\to 0$ while $\rho_{xy}$ approaches a
+non-zero value smaller than its ""classical value"" $H/nec$, i.e.
+$0<\rho_{xy}<H/nec$. A still higher characteristic magnetic field, $H_c^*>
+H_c$, at which the Hall resistance is $T$ independent and roughly equal to its
+classical value, $\rho_{xy}\approx H/nec$, marks an additional crossover to a
+highfield regime (probably to a Fermi-insulator) in which $\rho_{xy} > H/nec$
+and possibly diverges as $T\to 0$. We also highlight a profound analogy between
+the H-SIT and quantum-Hall liquid to insulator transitions (QHIT).",1504.08115v3
+2015-09-07,Finite Size Effect in Amorphous Indium oxide,"We study the low temperature magneto-transport properties of several highly
+disordered amorphous Indium oxide(a:InO) samples. Simultaneously fabricated
+devices comprising a 2-dimensional (2D) film and 10 $\mu$m long wires of
+different widths were measured to investigate the effect of size as we approach
+the 1D limit, which is around 4 times the correlation length, and happens to be
+around 100 nm for a:InO. The film and the wires showed magnetic field ({\it B})
+induced superconductor to insulator transition (SIT). In the superconducting
+side, the resistance increased with decrease in wire width, whereas, an
+opposite trend is observed in the insulating side. We find that this effect can
+be explained in light of charge-vortex duality picture of the SIT. Resistance
+of the 2D film follows an activated behavior over the temperature ($T$),
+whereas, the wires show a crossover from the high-$T$ activated to a
+$T$-independent behavior. At high temperature regime the wires' resistance
+follow the film's until they deviate and became independent of $T$. We find
+that temperature at which this deviation occurs evolve with magnetic field and
+the width of the wire, which show the effect of finite size on the transport.",1509.02033v2
+2015-11-09,Origin and Enhancement of Spin Polarization Current in Diluted Magnetic Oxides by Oxygen Vacancies and Nano Grain Size,"Spin polarized current is the main ingredient of diluted magnetic oxides due
+to its potential manipulation in spintronic devices. However, most research has
+focused on ferromagnetic properties rather than polarization of electric
+current, because direct measurements were difficult and the origin of spin
+polarized currents has yet to be fully understood. The method to increase the
+spin polarized current percentage is beyond practical consideration at the
+present status. To target this problem, we focus on the role of oxygen
+vacancies and nano grain size on the spin polarized current, which are
+controlled by growing the Co-doped ZnO thin-films at room temperature in a
+reducing atmosphere [Ar + (1% ~ 30%) H2]. We found that the conductivity
+increases with an increase in oxygen vacancies via two independent channels:
+the variable range hopping (VRH) within localized states and the itinerant
+transport in the conduction band. The Andreev Reflection measurements prove
+that the VRH conduction is equivalent to spin polarized current. Transport
+measurements show that the best way to increase the VRH content, or the
+percentage of spin polarized current, is to increase oxygen vacancy
+concentration and to reduce grain size and lattice constants of the films.",1511.02630v1
+2016-06-17,Long-range charge density wave proximity effect at cuprate-manganate interfaces,"The interplay between charge density waves (CDWs) and high-temperature
+superconductivity is currently under intense investigation. Experimental
+research on this issue is difficult because CDW formation in bulk copper-oxides
+is strongly influenced by random disorder, and a long-range-ordered CDW state
+in high magnetic fields is difficult to access with spectroscopic and
+diffraction probes. Here we use resonant x-ray scattering in zero magnetic
+field to show that interfaces with the metallic ferromagnet
+La$_{2/3}$Ca$_{1/3}$MnO$_3$ greatly enhance CDW formation in the optimally
+doped high-temperature superconductor YBa$_2$Cu$_3$O$_{6+\delta}$ ($\bf \delta
+\sim 1$), and that this effect persists over several tens of nm. The wavevector
+of the incommensurate CDW serves as an internal calibration standard of the
+charge carrier concentration, which allows us to rule out any significant
+influence of oxygen non-stoichiometry, and to attribute the observed phenomenon
+to a genuine electronic proximity effect. Long-range proximity effects induced
+by heterointerfaces thus offer a powerful method to stabilize the charge
+density wave state in the cuprates, and more generally, to manipulate the
+interplay between different collective phenomena in metal oxides.",1606.05531v2
+2016-09-23,Quantum Anomalous Hall and Half-metallic Phases in Ferromagnetic (111) Bilayers of 4d and 5d Transition Metal Perovskites,"Extraordinary electronic phases can form in artificial oxide
+heterostructures, which will provide a fertile ground for new physics and also
+give rise to novel device functions. Based on a systematic first-principles
+density functional theory study of the magnetic and electronic properties of
+the (111) superlattices (ABO3)2/(AB'O3)10 of 4d and 5d transition metal
+perovskite (B = Ru, Rh, Ag, Re, Os, Ir, Au; AB'O3 = LaAlO3, SrTiO3), we
+demonstrate that due to quantum confinement, bilayers (LaBO3)2 (B = Ru, Re, Os)
+and (SrBO3)2 (B = Rh, Os, Ir) are ferromagnetic with ordering temperatures up
+to room temperature. In particular, bilayer (LaOsO3)2 is an exotic
+spin-polarized quantum anomalous Hall insulator, while the other ferromagnetic
+bilayers are metallic with large Hall conductances comparable to the
+conductance quantum. Furthermore, bilayers (LaRuO3)2 and (SrRhO3)2 are
+half-metallic, while bilayer (SrIrO3)2 exhibits peculiar colossal magnetic
+anisotropy. Our findings thus show that 4d and 5d metal perovskite (111)
+bilayers are a class of quasi-two-dimensional materials for exploring exotic
+quantum phases and also for advanced applications such as low-power
+nanoelectronics and oxide spintronics.",1609.07383v1
+2018-03-31,Understanding current-driven dynamics of magnetic Néel walls in heavy metal/ferromagnetic metal/oxide trilayers,"We consider analytically current-driven dynamics of magnetic N\'{e}el walls
+in heavy metal/ferromagnetic metal/oxide trilayers where strong spin-orbit
+coupling and interfacial Dzyaloshinskii-Moriya interaction (i-DMI) coexist. We
+show that field-like spin-orbit torque (FL-SOT) with effective field along
+$\mathbf{n}\times\hat{\mathbf{J}}$ ($\mathbf{n}$ being the interface normal and
+$\hat{\mathbf{J}}$ being the charge current direction) and i-DMI induced torque
+can both lead to Walker breakdown suppression meanwhile leaving the wall
+mobility (velocity versus current density) unchanged. However, i-DMI itself can
+not induce the ""universal absence of Walker breakdown"" (UAWB) while FL-SOT
+exceeding a certain threshold can. Finitely-enlarged Walker limits before UAWB
+are theoretically calculated and well explain existing data. In addition,
+change in wall mobility and even its sign-inversion can be understood only if
+the anti-damping-like (ADL) SOT is appended. For N\'{e}el walls in
+ferromagnetic-metal layer with both perpendicular and in-plane anisotropies, we
+have calculated the respective modifications of wall mobility under the
+coexistence of spin-transfer torque, SOTs and i-DMI. Analytics shows that in
+trilayers with perpendicular anisotropy strong enough spin Hall angle and
+appropriate sign of i-DMI parameter can lead to sign-inversion in wall mobility
+even under small enough current density, while in those with in-plane
+anisotropy this only occurs for current density in a specific range.",1804.00127v4
+2017-01-11,Carrier driven coupling in ferromagnetic oxide heterostructures,"Transition metal oxides are well known for their complex magnetic and
+electrical properties. When brought together in heterostructure geometries,
+they show particular promise for spintronics and colossal magnetoresistance
+applications. In this letter, we propose a new mechanism for the coupling
+between layers of itinerant ferromagnetic materials in heterostructures. The
+coupling is mediated by charge carriers that strive to maximally delocalize
+through the heterostructure to gain kinetic energy. In doing so, they force a
+ferromagnetic or antiferromagnetic coupling between the constituent layers. To
+illustrate this, we focus on heterostructures composed of SrRuO$_3$ and
+La$_{1-x}$A$_{x}$MnO$_3$ (A=Ca/Sr). Our mechanism is consistent with
+antiferromagnetic alignment that is known to occur in multilayers of
+SrRuO$_3$-La$_{1-x}$A$_{x}$MnO$_3$. To support our assertion, we present a
+minimal Kondo-lattice model which reproduces the known magnetization properties
+of such multilayers. In addition, we discuss a quantum well model for
+heterostructures and argue that the spin-dependent density of states determines
+the nature of the coupling. As a smoking gun signature, we propose that
+bilayers with the same constituents will oscillate between ferromagnetic and
+antiferromagnetic coupling upon tuning the relative thicknesses of the layers.",1701.03117v1
+2018-05-22,FMR-related phenomena in spintronic devices,"Spintronic devices, such as non-volatile magnetic random access memories and
+logic devices, have attracted considerable attention as potential candidates
+for future high efficient data storage and computing technology. In a heavy
+metal or other emerging material with strong spin-orbit coupling (SOC), the
+charge currents induce spin currents or spin accumulations via SOC. The
+generated spin currents can exert spin-orbit torques (SOTs) on an adjacent
+ferromagnet, which opens up a new way to realize magnetization dynamics and
+switching of the ferromagnetic layer for spintronic devices. In the SOT scheme,
+the charge-to-spin interconversion efficiency (SOT efficiency) is an important
+figure of merit for applications. For the effective characterization of this
+efficiency, the ferromagnetic resonance (FMR) based methods, such as the spin
+transfer torque ferromagnetic resonance (ST-FMR) and the spin pumping, are
+common utilized in addition to low frequency harmonic or dc measurements. In
+this review, we focus on the ST-FMR measurements for the evaluation of the SOT
+efficiency. We provide a brief summary of the different ST-FMR setups and data
+analysis methods. We then discuss ST-FMR and SOT studies in various materials,
+including heavy metals and alloys, topological insulators, two dimensional (2D)
+materials, interfaces with strong Rashba effect, antiferromagnetic materials,
+two dimensional electron gas (2DEG) in oxide materials and oxidized nonmagnetic
+materials.",1805.08496v1
+2008-07-10,Modeling of Spin Metal-Oxide-Semiconductor Field-Effect-Transistor: A Non-Equilibrium Green's Function Approach with Spin Relaxation,"A spin metal-oxide-semiconductor field-effect-transistor (spin MOSFET), which
+combines a Schottky-barrier MOSFET with ferromagnetic source and drain
+contacts, is a promising device for spintronic logic. Previous simulation
+studies predict that this device should display a very high magnetoresistance
+(MR) ratio (between the cases of parallel and anti-parallel magnetizations) for
+the case of half-metal ferromagnets (HMF). We use the non-equilibrium Green's
+function (NEGF) formalism to describe tunneling and carrier transport in this
+device and to incorporate spin relaxation at the HMF-semiconductor interfaces.
+Spin relaxation at interfaces results in non-ideal spin injection. Minority
+spin currents arise and dominate the leakage current for anti-parallel
+magnetizations. This reduces the MR ratio and sets a practical limit for spin
+MOSFET performance. We found that MR saturates at a lower value for smaller
+source-to-drain bias. In addition, spin relaxation at the detector side is
+found to be more detrimental to MR than that at the injector side, for drain
+bias less than the energy difference of the minority spin edge and the Fermi
+level.",0807.1709v2
+2016-05-11,Percolation via combined electrostatic and chemical doping in complex oxide films,"Stimulated by experimental advances in electrolyte gating methods, we
+investigate theoretically percolation in thin films of inhomogenous complex
+oxides, such as La$_{1-x}$Sr$_{x}$CoO$_{3}$ (LSCO), induced by a combination of
+bulk chemical and surface electrostatic doping. Using numerical and analytical
+methods, we identify two mechanisms that describe how bulk dopants reduce the
+amount of electrostatic surface charge required to reach percolation: (i)
+bulk-assisted surface percolation, and (ii) surface-assisted bulk percolation.
+We show that the critical surface charge strongly depends on the film thickness
+when the film is close to the chemical percolation threshold. In particular,
+thin films can be driven across the percolation transition by modest surface
+charge densities \emph{via} surface-assisted bulk percolation. If percolation
+is associated with the onset of ferromagnetism, as in LSCO, we further
+demonstrate that the presence of critical magnetic clusters extending from the
+film surface into the bulk results in considerable volume enhancement of the
+saturation magnetization, with pronounced experimental consequences. These
+results should significantly guide experimental work seeking to verify
+gate-induced percolation transitions in such materials.",1605.03463v1
+2017-10-06,3d Transition Metals and Oxides within Carbon Nanotubes by Co-Pyrolysis of Metallocene & Camphor: High Filling Efficiency and Self-Organized Structures,"We demonstrate that a single zone furnace with a modified synthesis chamber
+design is sufficient to obtain metal (Fe, Co or Ni) filled carbon nanotubes
+(CNT) with high filling efficiency and controlled morphology. Samples are
+formed by pyrolysis of metallocenes, a synthesis technique that otherwise
+requires a dual zone furnace. Respective metallocene in all three cases are
+sublimed in powder form, a crucial factor for obtaining high filling
+efficiency. While Fe@CNT is routinely produced using this technique,
+well-formed Ni@CNT or Co@CNT samples are reported for the first time. This is
+achieved by sublimation of nickelocene (or cobaltocene) in combination with
+'camphor'. These samples exhibit some of the highest saturation magnetization
+(Ms) values, at least an order of magnitude higher than that reported for Ni or
+Co filled CNT, by aerosol assisted pyrolysis. The results also elucidate on why
+Ni or Co@CNT are relatively difficult to obtain by pyrolyzing powder
+metallocene alone. Overall, a systematic variation of synthesis parameters
+provides insights for obtaining narrow length and diameter distribution and
+reduced residue particles outside filled CNT - factors which are important for
+device related applications. Finally, the utility of this technique is
+demonstrated by obtaining highly aligned forest of Fe2O3@CNT, wherein Fe2O3 is
+a functional magnetic oxide relevant to spintronics and battery applications.",1710.02413v1
+2018-01-05,Large current modulation and tunneling magnetoresistance change by a side-gate electric field in a GaMnAs-based vertical spin metal-oxide-semiconductor field-effect transistor,"A vertical spin metal-oxide-semiconductor field-effect transistor (spin
+MOSFET) is a promising low-power device for the post scaling era. Here, using a
+ferromagnetic-semiconductor GaMnAs-based vertical spin MOSFET with a GaAs
+channel layer, we demonstrate a large drain-source current IDS modulation by a
+gate-source voltage VGS with a modulation ratio up to 130%, which is the
+largest value that has ever been reported for vertical spin field-effect
+transistors thus far. We find that the electric field effect on indirect
+tunneling via defect states in the GaAs channel layer is responsible for the
+large IDS modulation. This device shows a tunneling magnetoresistance (TMR)
+ratio up to ~7%, which is larger than that of the planar-type spin MOSFETs,
+indicating that IDS can be controlled by the magnetization configuration.
+Furthermore, we find that the TMR ratio can be modulated by VGS. This result
+mainly originates from the electric field modulation of the magnetic anisotropy
+of the GaMnAs ferromagnetic electrodes as well as the potential modulation of
+the nonmagnetic semiconductor GaAs channel layer. Our findings provide
+important progress towards high-performance vertical spin MOSFETs.",1801.01670v1
+2018-10-24,Radiation Damage and Thermal Recovery of Perovskite Superconductor Yttrium Barium Copper Oxide,"High temperature superconducting materials are being considered to generate
+the magnetic fields required for the confinement of plasma in fusion reactors.
+The present study aims to assess the microstructural degradation resulting from
+ion implantation at room temperature under two implantation conditions in
+Yttrium Barium Copper Oxide (YBCO) tapes. Xray Diffraction (XRD) and high
+resolution characterisation techniques including Atom Probe Tomography (APT)
+and Transmission Electron Microscopy (TEM) analyses were used to correlate
+alterations in superconducting behaviour measured using a Magnetic Properties
+Measurement System (MPMS) to amorphization and recovery caused by ion
+implantation. TEM analysis was performed to depth profile the degree of
+crystallinity (or lack thereof) on irradiated samples. SRIM predicted the
+damage depth at 900 nm below the sample surface of the 2 MeV Xe implanted
+sample and 450 nm beneath the surface of the 0.6 MeV Xe implanted sample. 2 MeV
+Xe implantation caused the superconducting temperature to decrease by 10 K and
+the critical current density to display a 10 fold reduction. Post irradiation
+heat treatments up to 600C caused recrystallisation of the irradiated layer,
+but also oxygen loss and alterations in grain size. The recrystallised grain
+orientation was random in TEM lamellae, however, bulk samples re-grew along the
+original crystal orientation provided that some of the original material was
+not amorphized (ie if they nucleated on crystalline YBCO). This is extremely
+promising for the thermal recovery of tokamak components.",1810.10477v3
+2019-10-15,Integration of the Noncollinear Antiferromagnetic Metal Mn3Sn onto Ferroelectric Oxides for Electric-Field Control,"Non-collinear antiferromagnetic materials have received dramatically
+increasing attention in the field of spintronics as their exotic topological
+features such as the Berry-curvature-induced anomalous Hall effect and possible
+magnetic Weyl states could be utilized in future topological antiferromagnetic
+spintronic devices. In this work, we report the successful integration of the
+antiferromagnetic metal Mn3Sn thin films onto ferroelectric oxide PMN-PT. By
+optimizing growth, we realized the large anomalous Hall effect with small
+switching magnetic fields of several tens mT fully comparable to those of bulk
+Mn3Sn single crystals, anisotropic magnetoresistance and negative parallel
+magnetoresistance in Mn3Sn thin films with antiferromagnetic order, which are
+similar to the signatures of the Weyl state in bulk Mn3Sn single crystals. More
+importantly, we found that the anomalous Hall effect in antiferromagnetic Mn3Sn
+thin films can be manipulated by electric fields applied onto the ferroelectric
+materials, thus demonstrating the feasibility of Mn3Sn-based topological
+spintronic devices operated in an ultralow power manner.",1910.06555v1
+2020-04-16,Intertwined density waves in a metallic nickelate,"Nickelates are a rich class of materials, ranging from insulating magnets to
+superconductors. But for stoichiometric materials, insulating behavior is the
+norm, as for most late transition metal oxides. Notable exceptions are the 3D
+perovskite LaNiO$_3$, an unconventional paramagnetic metal, and the layered
+Ruddlesden-Popper phases R$_4$Ni$_3$O$_{10}$, (R=La, Pr, Nd). The latter are
+particularly intriguing because they exhibit an unusual metal-to-metal
+transition. Here, we demonstrate that this transition results from an
+incommensurate density wave with both charge and magnetic character that lies
+intermediate in behavior between the metallic density wave seen in chromium
+metal and the insulating stripes typically found in layered nickelates. As
+such, R$_4$Ni$_3$O$_{10}$, which appears to be the first known example of an
+itinerant spin density wave in a 3d transition metal oxide, represents an
+important bridge between the paramagnetism of 3D metallic LaNiO$_3$ at higher
+nickel valence and the polaronic behavior of quasi-2D R$_{2-x}$Sr$_x$NiO$_4$ at
+lower nickel valence.",2004.07897v1
+2021-01-12,Persistence of Flare-Driven Atmospheric Chemistry on Rocky Habitable Zone Worlds,"Low-mass stars show evidence of vigorous magnetic activity in the form of
+large flares and coronal mass ejections. Such space weather events may have
+important ramifications for the habitability and observational fingerprints of
+exoplanetary atmospheres. Here, using a suite of three-dimensional coupled
+chemistry-climate model (CCM) simulations, we explore effects of time-dependent
+stellar activity on rocky planet atmospheres orbiting G-, K-, and M-dwarf
+stars. We employ observed data from the MUSCLES campaign and Transiting
+Exoplanet Satellite Survey and test a range of rotation period, magnetic field
+strength, and flare frequency assumptions. We find that recurring flares drive
+K- and M-dwarf planet atmospheres into chemical equilibria that substantially
+deviate from their pre-flare regimes, whereas G-dwarf planet atmospheres
+quickly return to their baseline states. Interestingly, simulated O$_2$-poor
+and O$_2$-rich atmospheres experiencing flares produce similar mesospheric
+nitric oxide abundances, suggesting that stellar flares can highlight otherwise
+undetectable chemical species. Applying a radiative transfer model to our CCM
+results, we find that flare-driven transmission features of bio-indicating
+species, such as nitrogen dioxide, nitrous oxide, and nitric acid, show
+particular promise for detection by future instruments.",2101.04507v3
+2017-09-07,Electron Accumulation and Emergent Magnetism in LaMnO3/SrTiO3 Heterostructures,"Emergent phenomena at polar-nonpolar oxide interfaces have been studied
+intensely in pursuit of next-generation oxide electronics and spintronics. Here
+we report the disentanglement of critical thicknesses for electron
+reconstruction and the emergence of ferromagnetism in polar-mismatched
+LaMnO3/SrTiO3 (001) heterostructures. Using a combination of element-specific
+X-ray absorption spectroscopy and dichroism, and first-principles calculations,
+interfacial electron accumulation and ferromagnetism have been observed within
+the polar, antiferromagnetic insulator LaMnO3. Our results show that the
+critical thickness for the onset of electron accumulation is as thin as 2 unit
+cells (UC), significantly thinner than the observed critical thickness for
+ferromagnetism of 5 UC. The absence of ferromagnetism below 5 UC is likely
+induced by electron over-accumulation. In turn, by controlling the doping of
+the LaMnO3, we are able to neutralize the excessive electrons from the polar
+mismatch in ultrathin LaMnO3 films and thus enable ferromagnetism in films as
+thin as 3 UC, extending the limits of our ability to synthesize and tailor
+emergent phenomena at interfaces and demonstrating manipulation of the
+electronic and magnetic structures of materials at the shortest length scales.",1709.02035v1
+2019-08-07,Evolution of topological superconductivity by orbital selective confinement in oxide nanowires,"We determine the optimal conditions to achieve topological superconducting
+phases having spin-singlet pairing for a planar nanowire with finite lateral
+width in the presence of an in-plane external magnetic field. We employ a
+microscopic description that is based on a three-band electronic model
+including both the atomic spin-orbit coupling and the inversion asymmetric
+potential at the interface between oxide band-gap insulators. We consider
+amplitudes of the pairing gap, spin-orbit interactions and electronic
+parameters that are directly applicable to nanowires of LaAlO$_3$-SrTiO$_3$.
+The lateral confinement introduces a splitting of the $d$-orbitals that alters
+the orbital energy hierarchy and significantly affects the electron filling
+dependence of the topological phase diagram. Due to the orbital directionality
+of the $t_{2g}$-states, we find that in the regime of strong confinement the
+onset of topological phases is pinned at electron filling where the quasi flat
+heavy bands start to get populated. The increase of the nanowire thickness
+leads to a changeover from sparse-to-dense distribution of topologically
+non-trivial domains which occurs at the cross-over associated to the orbital
+population inversion. These findings are corroborated by a detailed analysis of
+the most favorable topological superconducting phases in the electron
+doping-magnetic field plane highlighting the role of orbital selective
+confinement.",1908.02857v1
+2021-08-16,Neutron Scattering Signature of Phonon Renormalization in Nickel (II) Oxide,"The physics of mutual interaction of phonon quasiparticles with electronic
+spin degrees of freedom, leading to unusual transport phenomena of spin and
+heat, has been a subject of continuing interests for decades. Despite its
+pivotal role in transport processes, the effect of spin-phonon coupling on the
+phonon system, especially acoustic phonon properties, has so far been elusive.
+By means of inelastic neutron scattering and first-principles calculations,
+anomalous scattering spectral intensity from acoustic phonons was identified in
+the exemplary collinear antiferromagnetic nickel (II) oxide, unveiling strong
+spin-lattice correlations that renormalize the polarization of acoustic phonon.
+In particular, a clear magnetic scattering signature of the measured neutron
+scattering intensity from acoustic phonons is demonstrated by its momentum
+transfer and temperature dependences. The anomalous scattering intensity is
+successfully modeled with a modified magneto-vibrational scattering cross
+section, suggesting the presence of spin precession driven by phonon. The
+renormalization of phonon eigenvector is indicated by the observed
+""geometry-forbidden"" neutron scattering intensity from transverse acoustic
+phonon. Importantly, the eigenvector renormalization cannot be explained by
+magnetostriction but instead, it could result from the coupling between phonon
+and local magnetization of ions.",2108.07363v3
+2021-10-14,Superconductor-insulator transitions in three-dimensional indium-oxide at high pressures,"Experiments investigating magnetic-field-tuned superconductor-insulator
+transition (HSIT) mostly focus on two-dimensional material systems where the
+transition and its proximate ground-state phases, often exhibit features that
+are seemingly at odds with the expected behavior. Here we present a
+complementary study of a three-dimensional pressure-packed amorphous
+indium-oxide (InOx) powder where granularity controls the HSIT. Above a low
+threshold pressure of ~0.2 GPa, vestiges of superconductivity are detected,
+although neither a true superconducting transition nor insulating behavior are
+observed. Instead, a saturation at very high resistivity at low pressure is
+followed by saturation at very low resistivity at higher pressure. We identify
+both as different manifestations of anomalous metallic phases dominated by
+superconducting fluctuations. By analogy with previous identification of the
+low resistance saturation as a ""failed superconductor"", our data suggests that
+the very high resistance saturation is a manifestation of a ""failed insulator"".
+Above a threshold pressure of ~6 GPa, the sample becomes fully packed, and
+superconductivity is robust, with TC tunable with pressure. A quantum critical
+point at PC~25 GPa marks the complete suppression of superconductivity. For a
+finite pressure below PC, a magnetic field is shown to induce a HSIT from a
+true zero-resistance superconducting state to a weakly insulating behavior.
+Determining the critical field, HC, we show that similar to the 2D behavior,
+the insulating-like state maintains a superconducting character, which is
+quenched at higher field, above which the magnetoresistance decreases to its
+fermionic normal state value.",2110.07251v3
+2023-10-27,Spin Selective Evolution of Zhang-Rice State in Binary Transition Metal Oxide,"The Zhang-Rice (ZR) state is a strongly hybridized bound state formed by the
+transition metal and oxygen atoms. The spin-fluctuations within the ZR state
+are known to play an important role in high-$T_\mathrm{c}$ superconductivity in
+cuprates. Here, we employ a combination of angle-resolved photoemission
+spectroscopy (ARPES), X-ray photoemission spectroscopy (XPS), and {\it ab
+initio} embedded dynamical mean-field theory (eDMFT) to investigate the
+influence of magnetic ordering on the spectral characteristics of the valence
+band and Mn 2$p$ core-level in MnO (001) ultrathin films. Our results
+demonstrate that a complex spin-selective evolution of Mn 3$d$$-$O 2$p$
+hybridization develops due to the long-range antiferromagnetic (AFM) ordering.
+This hybridization significantly alters the spectral shape and weight of the ZR
+state. Specifically, in the AFM phase, we observed the sharpening of the ZR
+state and band folding with the periodicity of the AFM unit cell of MnO(001).
+We also demonstrated a strong connection between the spectral evolution of the
+ZR state and the non-local screening channels of the photoexcited core holes.
+Further, our detailed temperature-dependent study reveals the presence of
+short-range antiferromagnetic correlations that exist at much higher
+temperatures than $T_\mathrm{N}$. Such comprehensive studies showing the
+evolution of the ZR state across the magnetic transitions and its implication
+to the core-hole screening have never been reported in any 3$d$ binary
+transition metal oxides.",2310.17833v1
+2023-11-10,Provoking topology by octahedral tilting in strained SrNbO$_3$,"Transition metal oxides with a wide variety of electronic and magnetic
+properties offer an extraordinary possibility to be a platform for developing
+future electronics based on unconventional quantum phenomena, for instance, the
+topology. The formation of topologically non-trivial states is related to
+crystalline symmetry, spin-orbit coupling, and magnetic ordering. Here, we
+demonstrate how lattice distortions and octahedral rotation in SrNbO$_3$ films
+induce the band topology. By employing angle-resolved photoemission
+spectroscopy (ARPES) and density functional theory (DFT) calculations, we
+verify the presence of in-phase $a^0a^0c^+$ octahedral rotation in ultra-thin
+SrNbO$_3$ films, which causes the formation of topologically-protected Dirac
+band crossings. Our study illustrates that octahedral engineering can be
+effectively exploited for implanting and controlling quantum topological phases
+in transition metal oxides.",2311.06072v1
+2014-08-08,Spin-Orbital Order Modified by Orbital Dilution in Transition Metal Oxides: From Spin Defects to Frustrated Spins Polarizing Host Orbitals,"We study the $3d$ substitution in $4d$ transition metal oxides in the cases
+of $3d^3$ doping at either $3d^2$ or $4d^4$ sites which realize orbital
+dilution. We derive the effective $3d-4d$ (or $3d-3d$) superexchange in a Mott
+insulator with different ionic valencies, underlining the emerging structure of
+the spin-orbital coupling between the impurity and the host sites and
+demonstrate that it is qualitatively different from that encountered in the
+host itself. This derivation shows that the interaction between the host and
+the impurity depends in a crucial way on the type of doubly occupied $t_{2g}$
+orbital. One finds that in some cases, due to the quench of the orbital degree
+of freedom at the $3d$ impurity, the spin and orbital order within the host is
+drastically modified by doping. The impurity acts either as a spin defect
+accompanied by an orbital vacancy in the spin-orbital structure when the
+host-impurity coupling is weak, or it favors doubly occupied active orbitals
+(orbital polarons) along the $3d-4d$ bond leading to antiferromagnetic or
+ferromagnetic spin coupling. This competition between different magnetic
+couplings leads to quite different ground states. We find that magnetic
+frustration and spin degeneracy can be lifted by the quantum orbital flips of
+the host but they are robust in special regions of the incommensurate phase
+diagram. The spin-orbit coupling can lead to anisotropic spin and orbital
+patterns along the symmetry directions and cause a radical modification of the
+order imposed by the spin-orbital superexchange. Our findings are expected to
+be of importance for future theoretical understanding of experimental results
+for doped $4d$ transition metal oxides doped with $3d^3$ ions. We suggest how
+the local or global changes of the spin-orbital order induced by such
+impurities could be detected experimentally.",1408.1838v3
+2012-05-24,Turning ABO$_3$ antiferroelectrics into ferroelectrics: Design rules for practical rotation-driven ferroelectricity in double perovskites and A$_3$B$_2$O$_7$ Ruddlesden-Popper compounds,"Ferroic transition metal oxides, which exhibit spontaneous elastic,
+electrical, magnetic or toroidal order, exhibit functional properties that find
+use in ultrastable solid-state memories to sensors and medical imaging
+technologies. To realize multifunctional behavior, where one order parameter
+can be coupled to the conjugate field of another order parameter, however,
+requires a common microscopic origin for the long-range order. Here, we
+formulate a complete theory for a novel form of ferroelectricity, whereby a
+spontaneous and switchable polarization emerges from the destruction of an
+antiferroelectric state due to octahedral rotations and ordered cation
+sublattices. We then construct a materials design framework based on
+crystal-chemistry descriptors rooted in group theory, which enables the facile
+design of artificial oxides with large electric polarizations, P, simultaneous
+with small energetic switching barriers between +P and -P. We validate the
+theory with first principles density functional calculations on more than 16
+perovskite-structured oxides, illustrating it could be operative in any
+materials classes exhibiting two- or three-dimensional corner-connected
+octahedral frameworks. We show the principles governing materials selection of
+the ""layered"" systems originate in the lattice dynamics of the A cation
+displacements stabilized by the pervasive BO$_6$ rotations of single phase
+ABO$_3$ materials, whereby the latter distortions govern the optical band gaps,
+magnetic order and critical transition temperatures. Our approach provides the
+elusive route to the ultimate multifunctionality property control by an
+external electric field.",1205.5526v3
+2019-12-22,Two-dimensional electron systems in perovskite oxide heterostructures: Role of the polarity-induced substitutional defects,"The discovery of a two-dimensional electron system (2DES) at the interfaces
+of perovskite oxides such as LaAlO3 and SrTiO3 has motivated enormous efforts
+in engineering interfacial functionalities with this type of oxide
+heterostructures. However, its fundamental origins are still not understood,
+e.g. the microscopic mechanisms of coexisting interface conductivity and
+magnetism. Here we report a comprehensive spectroscopic investigation of the
+depth profile of 2DES-relevant Ti 3d interface carriers using depth- and
+element-specific techniques, standing-wave excited photoemission and resonant
+inelastic scattering. We found that one type of Ti 3d interface carriers, which
+give rise to the 2DES are located within 3 unit cells from the n-type interface
+in the SrTiO3 layer. Unexpectedly, another type of interface carriers, which
+are polarity-induced Ti-on-Al antisite defects, reside in the first 3 unit
+cells of the opposing LaAlO3 layer (~10 {\AA}). Our findings provide a
+microscopic picture of how the localized and mobile Ti 3d interface carriers
+distribute across the interface and suggest that the 2DES and 2D magnetism at
+the LaAlO3/SrTiO3 interface have disparate explanations as originating from
+different types of interface carriers.",1912.10384v3
+2020-10-20,Strong Ferromagnetism Achieved via Breathing Lattices in Atomically Thin Cobaltites,"Low-dimensional quantum materials that remain strongly ferromagnetic down to
+mono layer thickness are highly desired for spintronic applications. Although
+oxide materials are important candidates for next generation of spintronic,
+ferromagnetism decays severely when the thickness is scaled to the nano meter
+regime, leading to deterioration of device performance. Here we report a
+methodology for maintaining strong ferromagnetism in insulating LaCoO3 (LCO)
+layers down to the thickness of a single unit cell. We find that the magnetic
+and electronic states of LCO are linked intimately to the structural parameters
+of adjacent ""breathing lattice"" SrCuO2 (SCO). As the dimensionality of SCO is
+reduced, the lattice constant elongates over 10% along the growth direction,
+leading to a significant distortion of the CoO6 octahedra, and promoting a
+higher spin state and long-range spin ordering. For atomically thin LCO layers,
+we observe surprisingly large magnetic moment (0.5 uB/Co) and Curie temperature
+(75 K), values larger than previously reported for any mono layer oxide. Our
+results demonstrate a strategy for creating ultra thin ferromagnetic oxides by
+exploiting atomic hetero interface engineering,confinement-driven structural
+transformation, and spin-lattice entanglement in strongly correlated materials.",2010.09998v1
+2014-04-14,Behavior of nanoparticle clouds around a magnetized microsphere under magnetic and flow fields,"When a micron-sized magnetizable particle is introduced into a suspension of
+nanosized magnetic particles, the nanoparticles accumulate around the
+microparticle and form thick anisotropic clouds extended in the direction of
+the applied magnetic field. This phenomenon promotes colloidal stabilization of
+bimodal magnetic suspensions and allows efficient magnetic separation of
+nanoparticles used in bioanalysis and water purification. In the present work,
+size and shape of nanoparticle clouds under the simultaneous action of an
+external uniform magnetic field and the flow have been studied in details. In
+experiments, dilute suspension of iron oxide nanoclusters (of a mean diameter
+of 60 nm) was pushed through a thin slit channel with the nickel microspheres
+(of a mean diameter of 50$\mu$m) attached to the channel wall. The behavior of
+nanocluster clouds was observed in the steady state using an optical
+microscope. In the presence of strong enough flow, the size of the clouds
+monotonically decreases with increasing flow speed in both longitudinal and
+transverse magnetic fields. This is qualitatively explained by enhancement of
+hydrodynamic forces washing the nanoclusters away from the clouds. In the
+longitudinal field, the flow induces asymmetry of the front and the back
+clouds. To explain the flow and the field effects on the clouds, we have
+developed a simple model based on the balance of the stresses and particle
+fluxes on the cloud surface. This model, applied to the case of the magnetic
+field parallel to the flow, captures reasonably well the flow effect on the
+size and shape of the cloud and reveals that the only dimensionless parameter
+governing the cloud size is the ratio of hydrodynamic-to-magnetic forces - the
+Mason number. At strong magnetic interactions considered in the present work
+(dipolar coupling parameter $\alpha \geq 2$), the Brownian motion seems not to
+affect the cloud behavior.",1404.3927v1
+2020-11-04,Unveiling temperature dependence mechanisms of perpendicular magnetic anisotropy at Fe/MgO interfaces,"The perpendicular magnetic anisotropy (PMA) at magnetic transition
+metal/oxide interfaces is a key element in building out-of-plane magnetized
+magnetic tunnel junctions for spin-transfer-torque magnetic random access
+memory (STT-MRAM). Size downscaling renders magnetic properties more sensitive
+to thermal effects. Thus, understanding the temperature dependence of the
+magnetic anisotropy is crucial. In this work, we theoretically address the
+correlation between temperature dependence of PMA and magnetization in typical
+Fe/MgO-based structures. In particular, the possible mechanisms behind the
+experiments reporting deviations from the Callen and Callen scaling power law
+are analyzed. At ideal interfaces, first-principles calculations reveal (i)
+small high-order anisotropy constants compared to first order and (ii) enhanced
+exchange constants. Considering these two intrinsic effects in the atomistic
+simulations, the temperature-dependence of the total and layer-resolved
+anisotropy are found to follow the Callen and Callen scaling power law, thus
+ruling out an intrinsic microscopic mechanism underlying deviations from this
+law. Besides, two possible extrinsic macroscopic mechanisms are unveiled namely
+the influence of the dead layer, often present in the storage layer of STT-MRAM
+cells, and the spatial inhomogeneities of the interfacial magnetic anisotropy.
+About the first mechanism, we show that the presence of a dead layer tends to
+reduce the scaling exponents. In the second mechanism, increasing the
+percentage of inhomogeneity in the interfacial PMA is revealed to decrease the
+scaling exponent. These results allow us to explain the difference in scaling
+exponents relating anisotropy and magnetization thermal variations reported in
+earlier experiments. This is crucial for the understanding of the thermal
+stability of the storage layer magnetization in STT-MRAM applications.",2011.02220v3
+2022-05-06,Tuning the dynamics of chiral domain walls of ferrimagnetic films with the magneto-ionic effect,"The manipulation of magnetism with a gate voltage is expected to lead the way
+towards the realization of energy-efficient spintronics devices and
+high-performance magnetic memories. Exploiting magneto-ionic effects under
+micro-patterned electrodes in solid-state devices adds the possibility to
+modify magnetic properties locally, in a non-volatile and reversible way.
+Tuning magnetic anisotropy, magnetization and Dzyaloshinskii-Moriya interaction
+allows modifying at will the dynamics of non trivial magnetic textures such as
+skyrmions and chiral domain walls in magnetic race tracks. In this work, we
+illustrate efficient magneto-ionic effects in a ferrimagnetic Pt/Co/Tb stack
+using a ZrO2 thin layer as a solid state ionic conductor. When a thin layer of
+terbium is deposited on top of cobalt, it acquires a magnetic moment that
+aligns antiparallel to that of cobalt, reducing the effective magnetization.
+Below the micro-patterned electrodes, the voltage-driven migration of oxygen
+ions in a ZrO2 towards the ferrimagnetic stack partially oxidizes the Tb layer,
+leading to the local variation not only of the spontaneous magnetization, but
+also of the effective magnetic anisotropy and of the Dzyaloshinskii-Moriya
+interaction. This leads to a huge increase of the domain wall velocity, which
+varies from 10 m/s in the pristine state to 250 m/s after gating. This
+non-volatile and reversible tuning of the domain wall dynamics may lead to
+applications to reprogrammable magnetic memories or other spintronic devices.",2205.03158v1
+2023-10-02,Control of the magnetic anisotropy in multi-repeat Pt/Co/Al heterostructures using magneto-ionic gating,"Controlling magnetic properties through the application of an electric field
+is a significant challenge in modern nanomagnetism. In this study, we
+investigate the magneto-ionic control of magnetic anisotropy in the topmost Co
+layer in Ta/Pt/[Co/Al/Pt]$_n$/Co/Al/AlO$_\text{x}$ multilayer stacks comprising
+$n +1$ Co layers and its impact on the magnetic properties of the multilayers.
+We demonstrate that the perpendicular magnetic anisotropy can be reversibly
+quenched through gate-driven oxidation of the intermediary Al layer between Co
+and AlO$_\text{x}$, enabling dynamic control of the magnetic layers
+contributing to the out-of-plane remanence - varying between $n$ and $n +1$.
+For multilayer configurations with $n = 2$ and $n = 4$, we observe reversible
+and non-volatile additions of 1/3 and 1/5, respectively, to the anomalous Hall
+effect amplitude based on the applied gate voltage. Magnetic imaging reveals
+that the gate-induced spin-reorientation transition occurs through the
+propagation of a single 90$^{\circ}$ magnetic domain wall separating the
+perpendicular and in-plane anisotropy states. In the 5-repetition multilayer,
+the modification leads to a doubling of the period of the magnetic domains at
+remanence. These results demonstrate that the magneto-ionic control of the
+anisotropy of a single magnetic layer can be used to control the magnetic
+properties of coupled multilayer systems, extending beyond the gating effects
+on a single magnetic layer.",2310.01623v1
+2008-02-05,CO oxidation on Pd(100) at technologically relevant pressure conditions: A first-principles kinetic Monte Carlo study,"The possible importance of oxide formation for the catalytic activity of
+transition metals in heterogenous oxidation catalysis has evoked a lively
+discussion over the recent years. On the more noble transition metals (like Pd,
+Pt or Ag) the low stability of the common bulk oxides suggests primarily
+sub-nanometer thin oxide films, so-called surface oxides, as potential
+candidates that may be stabilized under gas phase conditions representative of
+technological oxidation catalysis. We address this issue for the Pd(100) model
+catalyst surface with first-principles kinetic Monte Carlo (kMC) simulations
+that assess the stability of the well-characterized (sqrt{5} x sqrt{5})R27
+surface oxide during steady-state CO oxidation. Our results show that at
+ambient pressure conditions the surface oxide is stabilized at the surface up
+to CO:O2 partial pressure ratios just around the catalytically most relevant
+stoichiometric feeds (p(CO):p(O2) = 2:1). The precise value depends sensitively
+on temperature, so that both local pressure and temperature fluctuations may
+induce a continuous formation and decomposition of oxidic phases during
+steady-state operation under ambient stoichiometric conditions.",0802.0553v1
+2011-04-06,"Sr flux stability against oxidation in oxide-MBE environment: flux, geometry, and pressure dependence","Maintaining stable fluxes for multiple source elements is a challenging task
+when the source materials have significantly different oxygen affinities in a
+complex-oxide molecular-beam-epitaxy (MBE) environment. Considering that Sr is
+one of the most easily oxidized and widely used element in various complex
+oxides, we took Sr as a probe to investigate the flux stability problem in a
+number of different conditions. Source oxidation was less for higher flux,
+extended port geometry, and un-melted source shape. The extended port geometry
+also eliminated the flux transient after opening a source shutter as observed
+in the standard port. We also found that the source oxidation occurred more
+easily on the crucible wall than on the surface of the source material. Atomic
+oxygen, in spite of its stronger oxidation effectiveness, did not make any
+difference in source oxidation as compared to molecular oxygen in this
+geometry. Our results may provide a guide for solutions to the source oxidation
+problem in oxide-MBE system.",1104.1117v1
+2013-01-10,Research on Interpore Distance of Anodic Aluminum Oxide Template,"The relationship between the interpore of anodic aluminum oxide (AAO)
+template and the influencing factors of electrolyte, temperature and oxidation
+voltage etc. was researched and summarized in this paper. It was pointed out
+that the interpore was influenced mostly by electrolyte type and oxidation
+voltage, and least by the electrolyte concentration and oxidation temperature.
+The interpore of AAO template increases with the oxidation voltage increases.
+By adjusting the electrolyte and oxidation voltage, a desired interpore of
+template can be acquired. To acquire a large interpore template can use
+electrolyte of phosphoric acid or chromic acid under a comparatively higher
+oxidation voltage. To acquire a small interpore template (with interpore within
+10nm) can use sulfate electrolyte under a comparatively lower oxidation voltage
+or pulse voltage. Alternatively, oxidizing with lower oxidation voltage in a
+mixed electrolyte of H2SO4 and Al2 (SO4)3, whereafter immersion in the mixture
+of HCl and CuCl2 to corrode the template for some time, until the angles of
+cell appear six holes with small pore diameter, the interpore of AAO template
+decrease to about 0.6 times of the original.",1301.2058v1
+2012-03-13,Understanding of the Retarded Oxidation Effects in Silicon Nanostructures,"In-depth understanding of the retarded oxidation phenomenon observed during
+the oxidation of silicon nanostructures is proposed. The wet thermal oxidation
+of various silicon nanostructures such as nanobeams, concave/convex nanorings
+and nanowires exhibits an extremely different and complex behavior. Such
+effects have been investigated by the modeling of the mechanical stress
+generated during the oxidation process explaining the retarded regime. The
+model describes the oxidation kinetics of silicon nanowires down to a few
+nanometers while predicting reasonable and physical stress levels at the
+Si/SiO$_{2}$ interface by correctly taking into account the relaxation effects
+in silicon oxide through plastic flow.",1203.2803v1
+2012-10-30,Competing Atomic and Molecular Mechanisms of Thermal Oxidation,"The oxidation of SiC and Si provide a unique opportunity for studying
+oxidation mechanisms because the product is the same, SiO2. Silicon oxidation
+follows a linear-parabolic law, with molecular oxygen identified as the
+oxidant. SiC oxidation obeys the same linear-parabolic law but has different
+rates and activation energies and exhibits much stronger face-dependence. Using
+results from first-principles calculations, we show that atomic and molecular
+oxygen are the oxidant for Si- and C-face SiC respectively. Comparing SiC with
+Si, we elucidate how the interface controls the competition between atomic and
+molecular mechanisms.",1210.7899v2
+2021-03-31,Effects of point defects on oxidation of 3C-SiC,"The influence of implantation-induced point defects (PDs) on SiC oxidation is
+investigated via molecular dynamics simulations. PDs generally increase the
+oxidation rate of crystalline grains. Particularly, accelerations caused by Si
+antisites and vacancies are comparable, and followed by Si interstitials, which
+are higher than those by C antisites and C interstitials. However, in the grain
+boundary (GB) region, defect contribution to oxidation is more complex, with C
+antisites decelerating oxidation. The underlying reason is the formation of a
+C-rich region along the oxygen diffusion pathway that blocks the access of O to
+Si and thus reduces the oxidation rate, as compared to the oxidation along a GB
+without defects.",2103.16742v1
+2013-11-18,Orbital magnetization of insulating perovskite transition-metal oxides with the net ferromagnetic moment in the ground state,"Modern theory of the orbital magnetization is applied to the series of
+insulating perovskite transition metal oxides (orthorhombic YTiO$_3$,
+LaMnO$_3$, and YVO$_3$, as well as monoclinic YVO$_3$), carrying a net
+ferromagnetic (FM) moment in the ground state. For these purposes, we use an
+effective Hubbard-type model, derived from the first-principles
+electronic-structure calculations and describing the behavior of magnetically
+active states near the Fermi level. The solution of this model in the
+mean-field Hartree-Fock approximation with the relativistic spin-orbit coupling
+typically gives us a distribution of the local orbital magnetic moments, which
+are related to the site-diagonal part of the density matrix $\hat{\cal D}$ by
+the ""standard"" expression $\boldsymbol{\mu}^0 = - \mu_{\rm B} \mathrm{Tr} \{
+\hat{\textbf{L}} \hat{\cal D} \}$ and which are usually well quenched by the
+crystal field. In this work, we evaluate ""itinerant"" corrections $\Delta
+\boldsymbol{\cal M}$ to the net FM moment, suggested by the modern theory. We
+show that these corrections are small and in most cases can be neglected.
+Nevertheless, the most interesting aspect of our analysis is that, even for
+these compounds, which are typically regarded as normal Mott insulators, the
+""itinerant"" corrections reveal a strong $\textbf{k}$-dependence in the
+reciprocal space, following the behavior of Chern invariants. Therefore, the
+small value of $\Delta \boldsymbol{\cal M}$ is the result of strong cancelation
+of relatively large contributions, coming from different parts of the Brillouin
+zone. We discuss details as well as possible implications of this cancelation,
+which depends on the crystal structure as well as the type of the magnetic
+ground state.",1311.4263v1
+2018-03-22,Direct observation of electron density reconstruction at the metal-insulator transition in NaOsO3,"5d transition metal oxides offer new opportunities to test our understanding
+of the interplay of correlation effects and spin-orbit interactions in
+materials in the absence of a single dominant interaction. The subtle balance
+between solid-state interactions can result in new mechanisms that minimize the
+interaction energy, and in material properties of potential use for
+applications. We focus here on the 5d transition metal oxide NaOsO3, a strong
+candidate for the realization of a magnetically driven transition from a
+metallic to an insulating state exploiting the so-called Slater mechanism.
+Experimental results are derived from non-resonant and resonant x-ray single
+crystal diffraction at the Os L-edges. A change in the crystallographic
+symmetry does not accompany the metal-insulator transition in the Slater
+mechanism and, indeed, we find no evidence of such a change in NaOsO3. An
+equally important experimental observation is the emergence of the (300) Bragg
+peak in the resonant condition with the onset of magnetic order. The intensity
+of this space-group forbidden Bragg peak continuously increases with decreasing
+temperature in line with the square of intensity observed for an allowed
+magnetic Bragg peak. Our main experimental results, the absence of crystal
+symmetry breaking and the emergence of a space-group forbidden Bragg peak with
+developing magnetic order, support the use of the Slater mechanism to interpret
+the metal-insulator transition in NaOsO3. We successfully describe our
+experimental results with simulations of the electronic structure and, also,
+with an atomic model based on the established symmetry of the crystal and
+magnetic structure.",1803.08271v5
+2019-04-02,Relationship between charge redistribution and ferromagnetism at the heterointerface between perovskite oxides LaNiO$_3$ and LaMnO$_3$,"To investigate the relationship between the charge redistribution and
+ferromagnetism at the heterointerface between perovskite transition-metal
+oxides LaNiO$_3$ (LNO) and LaMnO$_3$ (LMO), we performed x-ray absorption
+spectroscopy and x-ray magnetic circular dichroism (XMCD) measurements. In the
+LNO/LMO heterostructures with asymmetric charge redistribution, the electrons
+donated from Mn to Ni ions are confined within one monolayer (ML) of LNO at the
+interface, whereas holes are distributed over 3-4 ML on the LMO side. A
+detailed analysis of the Ni-$L_{2,3}$ and Mn-$L_{2,3}$ XMCD spectra reveals
+that Ni magnetization is induced only by the Ni$^{2+}$ ions in the 1 ML LNO
+adjacent to the interface, while the magnetization of Mn ions is increased in
+the 3-4 ML LMO of the interfacial region. The characteristic length scale of
+the emergent (increased) interfacial ferromagnetism of the LNO (LMO) layers is
+in good agreement with that of the charge distribution across the interface,
+indicating a close relationship between the charge redistribution due to the
+interfacial charge transfer and the ferromagnetism of the LNO/LMO interface.
+Furthermore, the XMCD spectra clearly demonstrate that the vectors of induced
+magnetization of both ions are aligned ferromagnetically, suggesting that the
+delicate balance between the exchange interactions occurring inside each layer
+and across the interface may induce the canted ferromagnetism of Ni$^{2+}$
+ions, resulting in weak magnetization in the 1 ML LNO adjacent to the
+interface.",1904.01335v1
+2021-07-02,Interplay between singlet and triplet pairings in multi-band two-dimensional oxide superconductors,"We theoretically study the superconducting properties of multi-band
+two-dimensional transition metal oxide superconductors by analyzing not only
+the role played by conventional singlet pairings, but also by the triplet order
+parameters, favored by the spin-orbit couplings present in these ma- terials.
+In particular, we focus on the two-dimensional electron gas at the (001)
+interface between LaAlO3 and SrTiO3 band insulators where the low electron
+densities and the sizeable spin-orbit couplings affect the superconducting
+features. Our theoretical study is based on an extended su- perconducting
+mean-field analysis of the typical multi-band tight-binding Hamiltonian, as
+well as on a parallel analysis of the effective electronic bands in the
+low-momentum limit, including static on-site and inter-site intra-band
+attractive potentials under applied magnetic fields. The presence of triplet
+pairings is able to strongly reduce the singlet order parameters which, as a
+result, are no longer a monotonic function of the charge density. The interplay
+between the singlet and the triplet pairings affects the dispersion of
+quasi-particle excitations in the Brillouin zone and also induces anisotropy in
+the superconducting behavior under the action of an in-plane and of an out-
+of-plane magnetic fields. Finally, non-trivial topological superconducting
+states become stable as a function of the charge density, as well as of the
+magnitude and of the orientation of the magnetic field. In addition to the
+chiral, time-reversal breaking, topological superconducting phase, favored by
+the linear Rashba couplings and by the on-site attractive potentials in the
+presence of an out- of-plane magnetic field, we find that a time-reversal
+invariant topological helical superconducting phase is promoted by not-linear
+spin-orbit couplings and by the inter-site attractive interactions in the
+absence of magnetic field.",2107.01100v2
+2015-08-05,Atomistic details of oxide surfaces and surface oxidation: the example of copper and its oxides,"The oxidation and corrosion of metals are fundamental problems in materials
+science and technology that have been studied using a large variety of
+experimental and computational techniques. Here we review some of the recent
+studies that have led to significant advances in our atomic-level understanding
+of copper oxide, one of the most studied and best understood metal oxides. We
+show that a good atomistic understanding of the physical characteristics of
+cuprous (Cu$_2$O) and cupric (CuO) oxide and of some key processes of their
+formation has been obtained. Indeed, the growth of the oxide has been shown to
+be epitaxial with the surface and to proceed, in most cases, through the
+formation of oxide nano-islands which, with continuous oxygen exposure, grow
+and eventually coalesce. We also show how electronic structure calculations
+have become increasingly useful in helping to characterise the structures and
+energetics of various Cu oxide surfaces. However a number of challenges remain.
+For example, it is not clear under which conditions the oxidation of copper in
+air at room temperature (known as native oxidation) leads to the formation of a
+cuprous oxide film only, or also of a cupric overlayer. Moreover, the atomistic
+details of the nucleation of the oxide islands are still unknown. We close our
+review with a brief perspective on future work and discuss how recent advances
+in experimental techniques, bringing greater temporal and spatial resolution,
+along with improvements in the accuracy, realism and timescales achievable with
+computational approaches make it possible for these questions to be answered in
+the near future.",1508.01005v1
+2007-10-18,"Growth, Structure and Properties of BiFeO3-BiCrO3 Films obtained by Dual Cross Beam PLD","The properties of epitaxial Bi2FeCrO6 thin films, recently synthesized by
+pulsed laser deposition, have partially confirmed the theoretical predictions
+(i.e. a magnetic moment of 2 muB per formula unit and a polarization of ~80
+microC/cm2 at 0K). The existence of magnetic ordering at room temperature for
+this material is an unexpected but very promising result that needs to be
+further investigated. Since magnetism is assumed to arise from the exchange
+interaction between the Fe and Cr cations, the magnetic behaviour is strongly
+dependent on both their ordering and the distance between them. We present here
+the successful synthesis of epitaxial Bi2FexCryO6 (BFCO x/y) films grown on
+SrTiO3 substrates using dual crossed beam pulsed laser deposition. The crystal
+structure of the films has different types of (111)-oriented superstructures
+depending on the deposition conditions. The multiferroic character of BFCO
+(x/y) films is proven by the presence of both ferroelectric and magnetic
+hysteresis at room temperature. The oxidation state of Fe and Cr ions in the
+films is shown to be 3+ only and the difference in macroscopic magnetization
+with Fe/Cr ratio composition could only be due to ordering of the Cr3+ and Fe3+
+cations therefore to the modification of the exchange interaction between them.",0710.3424v1
+2007-11-08,Spin Frustration and Magnetic Exchange in Cobalt Aluminum Oxide Spinels,"We report on x-ray diffraction, magnetic susceptibility, electron- spin
+resonance and heat- capacity studies of Co[Al_1-xCo_x]_2O_4 for Co
+concentrations 0<x<1. In this spinel system only the A-site Co^2+ cation is
+magnetic, while the non-magnetic B-site Al^3+ is substituted by the low-spin
+non-magnetic Co^3+, and it is possible to investigate the complete phase
+diagram from Co^2+Al^3+_2O_4 to Co^2+Co^3+_2O_4. All samples reveal large
+negative Curie-Weiss temperatures Theta_CW of the order of -110 K independent
+of concentration, which is attributed to a high multiplicity of the
+superexchange interactions between the A-site Co^2+ cations. A pure
+antiferromagnetic state is found for x = 1.0 and 0.9 with Neel temperatures T_N
+= 29.5 K and 21.2 K, respectively, as evidenced by lambda-like anomalies in the
+specific heat. Compositions with 0.3<x<0.75 show smeared out strongly reduced
+magnetic ordering temperatures. At low temperatures, a T^2.5 dependence of the
+specific heat is indicative of a spin-liquid state. For x < 0.2 a T^2
+dependence of the specific heat and a spin-glass like behavior of the
+susceptibility below T_f = 4.7 K are observed. The high value of the
+frustration parameter f = |Theta_CW|/T_f > 10 indicates the presence of strong
+spin frustration at least for x < 0.6. The frustration mechanism is attributed
+to competing nearest neighbor and next-nearest neighbor superexchange
+interactions between the A-site Co^2+ ions.",0711.1301v1
+2007-11-26,Quantum fluctuations in high field magnetization of 2D square lattice J1-J2 antiferromagnets,"The J1-J2 square lattice Heisenberg model with spin S=1/2 has three phases
+with long-range magnetic order and two unconventionally ordered phases
+depending on the ratio of exchange constants. It describes a number of recently
+found layered vanadium oxide compounds. A simple means of investigating the
+ground state is the study of the magnetization curve and high-field
+susceptibility. We discuss these quantities by using the spin-wave theory and
+the exact diagonalization in the whole J1-J2 plane. We compare both results and
+find good overall agreement in the sectors of the phase diagram with magnetic
+order. Close to the disordered regions the magnetization curve shows strong
+deviations from the classical linear behaviour caused by large quantum
+fluctuations and spin-wave approximation breaks down. On the FM side (J1<0)
+where one approaches the quantum gapless spin nematic ground state this region
+is surprisingly large. We find that inclusion of second order spin-wave
+corrections does not lead to fundamental improvement. Quantum corrections to
+the tilting angle of the ordered moments are also calculated. They may have
+both signs, contrary to the always negative first order quantum corrections to
+the magnetization. Finally we investigate the effect of the interlayer coupling
+and find that the quasi-2D picture remains valid up to |J_\perp/J1| ~ 0.3.",0711.4054v1
+2009-03-09,Interacting Superparamagnetism in La0.7Sr0.3MnO3 Nanoparticles,"The magnetic order of La0.7Sr0.3MnO3 nanoparticles (NPs) fabricated in a SPEX
+D8000 mill was systematically studied. The La0.7Sr0.3MnO3 nanocrystals grow
+from the milled constituent oxides during the milling processes. The
+magnetization data obtained by using a SQUID magnetometer show the NPs as a
+superparamagnet in terms of anhysteretic curves near room temperature.
+Unoverlaping of the scaled M(H-ext, T)/M-s vs. H-ext, T plots and the dc
+susceptibility obeying the Curie-Weiss behavior rather than the Curie law at
+high temperatures provide evidence that the NPs are interacting
+superparamagnetic ensembles. A mean-field correction to the Langevin function L
+([H-ext + alpha M]/k(B)T) worked well for the magnetic ordering of the NPs. By
+means of the Langevin fitting, the diameter of the NP was estimated to be lower
+than 15 nm, depending oil the milling time. The saturation magnetization of NPs
+varied from 48.5 em/g to 19 emu/g, with the higher value corresponding to a
+larger particle size. A core-shell structure of the NP was adopted, with the NP
+having the core-shell magnetically-effective mass density. This is applicable
+to the variation of the saturation magnetization with particle size.",0903.1565v1
+2009-04-28,Exotic magnetism in the alkali sesquoxides Rb4O6 and Cs4O6,"Among the various alkali oxides the sesquioxides Rb4O6 and Cs4O6 are of
+special interest. Electronic structure calculations using the local
+spin-density approximation predicted that Rb4O6 should be a half-metallic
+ferromagnet, which was later contradicted when an experimental investigation of
+the temperature dependent magnetization of Rb4O6 showed a low-temperature
+magnetic transition and differences between zero-field-cooled (ZFC) and
+field-cooled (FC) measurements. Such behavior is known from spin glasses and
+frustrated systems. Rb4O6 and Cs4O6 comprise two different types of dioxygen
+anions, the hyperoxide and the peroxide anions. The nonmagnetic peroxide anions
+do not contain unpaired electrons while the hyperoxide anions contain unpaired
+electrons in antibonding pi*-orbitals. High electron localization (narrow
+bands) suggests that electronic correlations are of major importance in these
+open shell p-electron systems. Correlations and charge ordering due to the
+mixed valency render p-electron-based anionogenic magnetic order possible in
+the sesquioxides. In this work we present an experimental comparison of Rb4O6
+and the related Cs4O6. The crystal structures are verified using powder x-ray
+diffraction. The mixed valency of both compounds is confirmed using Raman
+spectroscopy, and time-dependent magnetization experiments indicate that both
+compounds show magnetic frustration, a feature only previously known from d-
+and f-electron systems.",0904.4338v1
+2010-01-26,Scaling of transverse nuclear magnetic relaxation due to magnetic nanoparticle aggregation,"The aggregation of superparamagnetic iron oxide (SPIO) nanoparticles
+decreases the transverse nuclear magnetic resonance (NMR) relaxation time T2 of
+adjacent water molecules measured by a Carr-Purcell-Meiboom-Gill (CPMG)
+pulse-echo sequence. This effect is commonly used to measure the concentrations
+of a variety of small molecules. We perform extensive Monte Carlo simulations
+of water diffusing around SPIO nanoparticle aggregates to determine the
+relationship between T2 and details of the aggregate. We find that in the
+motional averaging regime T2 scales as a power law with the number N of
+nanoparticles in an aggregate. The specific scaling is dependent on the fractal
+dimension d of the aggregates. We find T2 N^{-0.44} for aggregates with d=2.2,
+a value typical of diffusion limited aggregation. We also find that in
+two-nanoparticle systems, T2 is strongly dependent on the orientation of the
+two nanoparticles relative to the external magnetic field, which implies that
+it may be possible to sense the orientation of a two-nanoparticle aggregate. To
+optimize the sensitivity of SPIO nanoparticle sensors, we propose that it is
+best to have aggregates with few nanoparticles, close together, measured with
+long pulse-echo times.",1001.4768v2
+2010-11-20,Depairing critical current achieved in superconducting thin films with through-thickness arrays of artificial pinning centers,"Large area arrays of through-thickness nanoscale pores have been milled into
+superconducting Nb thin films via a process utilizing anodized aluminum oxide
+thin film templates. These pores act as artificial flux pinning centers,
+increasing the superconducting critical current, Jc, of the Nb films. By
+optimizing the process conditions including anodization time, pore size and
+milling time, Jc values approaching and in some cases matching the
+Ginzburg-Landau depairing current of 30 MA/cm^2 at 5 K have been achieved - a
+Jc enhancement over as-deposited films of more than 50 times. In the field
+dependence of Jc, a matching field corresponding to the areal pore density has
+also been clearly observed. The effect of back-filling the pores with magnetic
+material has then been investigated. While back-filling with Co has been
+successfully achieved, the effect of the magnetic material on Jc has been found
+to be largely detrimental compared to voids, although a distinct influence of
+the magnetic material in producing a hysteretic Jc versus applied field
+behavior has been observed. This behavior has been tested for compatibility
+with currently proposed models of magnetic pinning and found to be most closely
+explained by a model describing the magnetic attraction between the flux
+vortices and the magnetic inclusions.",1011.4599v2
+2011-06-22,Spin correlations in the extended kagome system YBaCo3FeO7,"The transition metal based oxide YBaCo3FeO7 is structurally related to the
+mineral Swedenborgite SbNaBe4O7, a polar non-centrosymmetric crystal system.
+The magnetic Co3Fe sublattice consists of a tetrahedral network containing
+kagome-like layers with trigonal interlayer sites. This geometry causes
+frustration effects for magnetic ordering, which were investigated by
+magnetization measurements, M\""ossbauer spectroscopy, polarized neutron
+diffraction, and neutron spectroscopy. Magnetization measurement and neutron
+diffraction do not show long range ordering even at low temperature (1 K)
+although a strong antiferromagnetic coupling (~2000 K) is deduced from the
+magnetic susceptibility. Below 590 K, we observe two features, a spontaneous
+weak anisotropic magnetization hysteresis along the polar crystallographic axis
+and a hyperfine field on the Fe kagome sites, whereas the Fe spins on the
+interlayer sites remain idle. Below ~50 K, the onset of a hyperfine field shows
+the development of moments static on the M\""ossbauer time scale also for the Fe
+interlayer sites. Simultaneously, an increase of spin correlations is found by
+polarized neutron diffraction. The relaxation part of the dynamic response has
+been further investigated by high-resolution neutron spectroscopy, which
+reveals that the spin correlations start to freeze in below ~50 K. Monte Carlo
+simulations show that the neutron scattering results at lower temperatures are
+compatible with a recent proposal that the particular geometric frustration in
+the Swedenborgite structure promotes quasi one dimensional partial order.",1106.4465v1
+2014-02-27,Enhanced Stability of Skyrmions in Two-Dimensional Chiral Magnets with Rashba Spin-Orbit Coupling,"Recent developments have led to an explosion of activity on skyrmions in
+three-dimensional (3D) chiral magnets. Experiments have directly probed these
+topological spin textures, revealed their nontrivial properties, and led to
+suggestions for novel applications. However, in 3D the skyrmion crystal phase
+is observed only in a narrow region of the temperature-field phase diagram. We
+show here, using a general analysis based on symmetry, that skyrmions are much
+more readily stabilized in two-dimensional (2D) systems with Rashba spin-orbit
+coupling. This enhanced stability arises from the competition between field and
+easy-plane magnetic anisotropy and results in a nontrivial structure in the
+topological charge density in the core of the skyrmions. We further show that,
+in a variety of microscopic models for magnetic exchange, the required
+easy-plane anisotropy naturally arises from the same spin-orbit coupling that
+is responsible for the chiral Dzyaloshinskii-Moriya interactions. Our results
+are of particular interest for 2D materials like thin films, surfaces, and
+oxide interfaces, where broken surface-inversion symmetry and Rashba spin-orbit
+coupling naturally lead to chiral exchange and easy-plane compass anisotropy.
+Our theory gives a clear direction for experimental studies of 2D magnetic
+materials to stabilize skyrmions over a large range of magnetic fields down to
+T=0.",1402.7082v2
+2014-09-19,X-ray spectroscopic study of BaFeO$_{3}$ thin films; an Fe$ ^{4+}$ ferromagnetic insulator,"We investigated the electronic and magnetic properties of fully oxidized
+BaFeO3 thin films, which show ferromagnetic-insulating properties with cubic
+crystal structure, by hard x-ray photoemission spectroscopy (HAXPES), x-ray
+absorption spectroscopy (XAS) and soft x-ray magnetic circular dichroism
+(XMCD). We analyzed the results with configuration-interaction (CI)
+cluster-model calculations for Fe4+, which showed good agreement with the
+experimental results. We also studied SrFeO3 thin films, which have an Fe4+ ion
+helical magnetism in cubic crystal structure, but are metallic at all
+temperatures. We found that BaFeO3 thin films are insulating with large
+magnetization (2.1muB/formula unit) under ~ 1 T, using valence-band HAXPES and
+Fe 2p XMCD, which is consistent with the previously reported resistivity and
+magnetization measurements. Although Fe 2p core-level HAXPES and Fe 2p XAS
+spectra of BaFeO3 and SrFeO3 thin films are quite similar, we compared the
+insulating BaFeO3 to metallic SrFeO3 thin films with valence-band HAXPES. The
+CI cluster-model analysis indicates that the ground state of BaFeO3 is
+dominated by d5L (L: ligand hole) configuration due to the negative charge
+transfer energy, and that the band gap has significant O 2p character. We
+revealed that the differences of the electronic and magnetic properties between
+BaFeO3 and SrFeO3 arise from the differences in their lattice constants,
+through affecting the strength of hybridization and bandwidth.",1409.5538v1
+2016-07-04,First-principles investigations into the thermodynamics of cation disorder and it's impact on electronic structure and magnetic properties of spinel $Co\left(Cr_{1-x}Mn_{x} \right)_{2}O_{4}$,"Recent experiments on Mn doped multiferroic $CoCr_{2}O_{4}$ indicate that a
+possible distribution of Mn atoms among tetrahedrally and octahedrally
+coordinated sites in the spinel lattice give rise to different variations in
+the structural parameters and saturation magnetisations in different
+concentration regimes of Mn atoms substituting the Cr. A composition dependent
+magnetic compensation behaviour points to the role conversions of the magnetic
+constituents. In this work, we have investigated the thermodynamics of cation
+disorder in $Co\left(Cr_{1-x}Mn_{x}\right)_{2}O_{4}$ system and it's
+consequences on the structural, electronic and magnetic properties, using
+results from first-principles electronic structure calculations. We have
+computed the variations in the cation-disorder as a function of Mn
+concentration and the temperature and found that at the annealing temperature
+of the experiment many of the systems exhibit cation disorder. Our results
+support the interpretations of the experimental results regarding the
+qualitative variations in the sub-lattice occupancies and the associated
+magnetisation behaviour, with composition. We have analysed the variations in
+structural, magnetic and electronic properties of this system with variations
+in the compositions and the degree of cation disorder from the variations in
+their electronic structures and by using the ideas from crystal field theory.
+Our study provides a complete microscopic picture of the effects that are
+responsible for composition dependent behavioural differences of the properties
+of this system. This work lays down a general framework, based upon results
+from first-principles calculations, to understand and analyse the
+substitutional magnetic spinel oxides $A\left(B_{1-x}C_{x} \right)_{2}O_{4}$ in
+presence of cation disorder.",1607.00742v1
+2016-07-29,"A rock-salt type Li-based oxide, Li3Ni2RuO6, exhibiting a chaotic ferrimagnetism with cluster spin-glass dynamics and thermally frozen charge carriers","The area of research to discover new Li containing materials and to
+understand their physical properties has been of constant interest due to
+applications potential for rechargeable batteries. Here, we present the results
+of magnetic investigations on a Li compound, Li3Ni2RuO6, which was believed to
+be a ferrimagnet below 80K. While our neutron diffraction (ND) and isothermal
+magnetization (M) data support ferrimagnetism, more detailed magnetic studies
+establish that this ferrimagnetic phase exhibits some features similar to
+spin-glasses. In addition, we find another broad magnetic anomaly around 40-55
+K in magnetic susceptibility, attributable to cluster spin-glass phenomenon.
+Gradual dominance of cluster spin-glass dynamics with a decrease of temperature
+(T) and the apparent spread in freezing temperature suggest that the
+ferrimagnetism of this compound is a chaotic one. The absence of a unique
+freezing temperature for a crystalline material is interesting. In addition,
+pyroelectric current data reveals a feature in the range 40-50 K, attributable
+to thermally stimulated depolarization current. We hope this finding motivates
+future work to explore whether there is any intriguing correlation of such a
+feature with spin-glass dynamics. We attribute these magnetic and electric
+dipole anomalies to the crystallographic disorder intrinsic to this compound.",1607.08689v1
+2016-10-27,Coulomb spin liquid in anion-disordered pyrochlore Tb$_2$Hf$_2$O$_7$,"The charge ordered structure of ions and vacancies characterizing rare-earth
+pyrochlore oxides serves as a model for the study of geometrically frustrated
+magnetism. The organization of magnetic ions into networks of corner-sharing
+tetrahedra gives rise to highly correlated magnetic phases with strong
+fluctuations, including spin liquids and spin ices. It is an open question how
+these ground states governed by local rules are affected by disorder. In the
+pyrochlore Tb$_2$Hf$_2$O$_7$, we demonstrate that the vicinity of the
+disordering transition towards a defective fluorite structure translates into a
+tunable density of anion Frenkel disorder while cations remain ordered.
+Quenched random crystal fields and disordered exchange interactions can
+therefore be introduced into otherwise perfect pyrochlore lattices of magnetic
+ions. We show that disorder can play a crucial role in preventing long-range
+magnetic order at low temperatures, and instead induces a strongly-fluctuating
+Coulomb spin liquid with defect-induced frozen magnetic degrees of freedom.",1610.08714v3
+2018-04-06,Effect of Substrate Temperature on Structural and Magnetic Properties of c-axis Ori-ented Spinel Ferrite Ni0.65Zn0.35Fe2O4 (NZFO) Thin Films,"Varying the substrate temperature changes structural and magnetic properties
+of spinel ferrite NZFO thin films. XRD of films grown at different temperature
+display only 004 reflections, without any secondary peaks, showing growth
+orientation along the c axis. We find an increase in crystalline quality of
+these thin films with the rise of substrate temperature. The surface topography
+of the thin films grown on various growth temperatures conditions reveal that
+these films are smooth with low roughness, however the thin films grown at 800
+C exhibit lowest average and rms roughness among all thin films. We find iron
+and nickel to be more oxidized i,e greater Fe and Ni content in films grown and
+annealed at 700 C and 800 C, compared to those grown at lower temperatures. The
+magnetic moment is observed to increase with an increase of substrate
+temperature and all thin films possess high saturation magnetization and low
+coercive field at room temperature. Films grown at 800 C exhibit a
+ferrimagnetic paramagnetic phase transition well above room temperature. The
+observed large magnetizations with soft magnetic behavior in NZFO thin films
+above room temperature suggest potential application in memory, spintronics,
+and multifunctional devices.",1804.02458v2
+2008-07-30,Coexistence of static magnetism and superconductivity in SmFeAsO1-xFx as revealed by muon spin rotation,"The recent observation of superconductivity with critical temperatures up to
+55 K in the FeAs based pnictide compounds marks the first discovery of a non
+copper-oxide based layered high-Tc superconductor (HTSC) [1-3]. It has raised
+the suspicion that these new materials share a similar pairing mechanism to the
+cuprates, since both exhibit superconductivity following charge doping of a
+magnetic parent material. Here we present a muon spin rotation study on
+SmFeAsO1-xFx (x=0-0.30), which shows that static magnetism persists well into
+the superconducting regime. The analogy with the cuprates is quite surprising
+since the parent compounds appear to have different magnetic ground states:
+itinerant spin density wave for the pnictides contrasted with the Mott-Hubbard
+insulator in the cuprates. Our findings suggest that proximity to magnetic
+order and associated soft magnetic fluctuations, rather than the strong
+electronic correlations in the vicinity of a Mott-Hubbard-metal-to-insulator
+transition, may be the key ingredients of HTSC.",0807.4876v2
+2012-01-03,Reversible room-temperature ferromagnetism in Nb-doped SrTiO3 single crystals,"The search for oxide-based room-temperature ferromagnetism has been one of
+the holy grails in condensed matter physics. Room-temperature ferromagnetism
+observed in Nb-doped SrTiO3 single crystals is reported in this Rapid
+Communication. The ferromagnetism can be eliminated by air annealing (making
+the samples predominantly diamagnetic) and can be recovered by subsequent
+vacuum annealing. The temperature dependence of magnetic moment resembles the
+temperature dependence of carrier density, indicating that the magnetism is
+closely related to the free carriers. Our results suggest that the
+ferromagnetism is induced by oxygen vacancies. In addition, hysteretic
+magnetoresistance was observed for magnetic field parallel to current,
+indicating that the magnetic moments are in the plane of the samples. The x-ray
+photoemission spectroscopy, the static time-of-flight and the dynamic secondary
+ion mass spectroscopy and proton induced x-ray emission measurements were
+performed to examine magnetic impurities, showing that the observed
+ferromagnetism is unlikely due to any magnetic contaminant.",1201.0579v4
+2016-05-23,Beyond the Interface Limit: Structural and Magnetic Depth Profiles of Voltage-Controlled Magneto-Ionic Heterostructures,"Electric-field control of magnetism provides a promising route towards
+ultralow power information storage and sensor technologies. The effects of
+magneto-ionic motion have so far been prominently featured in the direct
+modification of interface chemical and physical characteristics. Here we
+demonstrate magnetoelectric coupling moderated by voltage-driven oxygen
+migration beyond the interface limit in relatively thick AlOx/GdOx/Co (15 nm)
+films. Oxygen migration and its ramifications on the Co magnetization are
+quantitatively mapped with polarized neutron reflectometry under thermal and
+electro-thermal conditionings. The depth-resolved profiles uniquely identify
+interfacial and bulk behaviors and a semi-reversible suppression and recovery
+of the magnetization. Magnetometry measurements show that the conditioning
+changes the microstructure so as to disrupt long-range ferromagnetic ordering,
+resulting in an additional magnetically soft phase. X-ray spectroscopy confirms
+electric field induced changes in the Co oxidation state but not in the Gd,
+suggesting that the GdOx transmits oxygen but does not source or sink it. These
+results together provide crucial insight into controlling magnetic
+heterostructures via magneto-ionic motion, not only at the interface, but also
+throughout the bulk of the films.",1605.07209v1
+2017-10-17,Nature of Lattice Distortions in Cubic Double-Perovskite Ba$_2$NaOsO$_6$,"We present detailed calculations of the electric field gradient (EFG) using a
+point charge approximation in Ba$_2$NaOsO$_6$, a Mott insulator with strong
+spin-orbit interaction. Recent $^{23}$Na nuclear magnetic resonance (NMR)
+measurements found that the onset of local point symmetry breaking, likely
+caused by the formation of quadrupolar order, precedes the formation of long
+range magnetic order in this compound. An extension of the static $^{23}$Na NMR
+measurements as a function of the orientation of a 15 T applied magnetic field
+at 8 K in the magnetically ordered phase is reported. Broken local cubic
+symmetry induces a non-spherical electronic charge distribution around the Na
+site and thus finite EFG, affecting the NMR spectral shape. We combine the
+spectral analysis as a function of the orientation of the magnetic field with
+calculations of the EFG to determine the exact microscopic nature of the
+lattice distortions present in low temperature phases of this material. We
+establish that orthorhombic distortions, constrained along the cubic axes of
+the perovskite reference unit cell, of oxygen octahedra surrounding Na nuclei
+are present in the magnetic phase.
+  Other common types of distortions often observed in oxide structures are
+considered as well.",1710.06052v1
+2019-09-20,Field-free spin-orbit torque switching through domain wall motion,"Deterministic current-induced spin-orbit torque (SOT) switching of
+magnetization in a heavy transition metal/ferromagnetic metal/oxide magnetic
+heterostructure with the ferromagnetic layer being perpendicularly-magnetized
+typically requires an externally-applied in-plane field to break the switching
+symmetry. We show that by inserting an in-plane magnetized ferromagnetic layer
+CoFeB underneath the conventional W/CoFeB/MgO SOT heterostructure,
+deterministic SOT switching of the perpendicularly-magnetized top CoFeB layer
+can be realized without the need of in-plane bias field. Kerr imaging study
+further unveils that the observed switching is mainly dominated by domain
+nucleation and domain wall motion, which might limit the potentiality of using
+this type of multilayer stack design for nanoscale SOT-MRAM application.
+Comparison of the experimental switching behavior with micromagnetic
+simulations reveals that the deterministic switching in our devices cannot be
+explained by the stray field contribution of the in-plane magnetized layer, and
+the roughness-caused N\'eel coupling effect might play a more important role in
+achieving the observed field-free deterministic switching.",1909.09604v1
+2019-10-05,"Enhancement of magnetodielectric coupling in 6H-perovskites Ba3RRu2O9 for heavier rare earth cations (R=Ho,Tb)","The role of rare-earth (R) ions on the magnetodielectric (MD) coupling is
+always intriguing and markedly different for different systems. Although many
+reports are available concerning this aspect in frustrated 3d-transition metal
+oxides, no such reports exist on higher d (4d/5d)-orbital based systems due to
+the rare availability of highly insulating 4d/5d-systems. Here, we
+systematically investigated the magnetic, dielectric, ferroelectric and
+magnetodielectric behavior of the 6H-perovskites Ba3RRu2O9 for different
+R-ions, namely, R= Sm, Tb and Ho, which magnetically order at 12, 9.5 and 10.2
+K respectively. For R=Tb and Ho, the temperature and magnetic-field dependent
+complex dielectric constant traces the magnetic features, which manifests MD
+coupling in this system. A weak magnetic-field (H) induced transition is
+observed for ~30 kOe, which is clearly captured in H-dependent dielectric
+measurements. No MD coupling is observed for Ba3SmRu2O9. The MD coupling is
+enhanced by a factor of 3 and 20 times for R=Tb and Ho, respectively, when
+compared to that of the Nd-counterpart. These results evidence the gradual
+enhancement of MD coupling with the introduction of heavier R-ions in this
+series, which is attributed to their larger moment values. A weak improper
+ferroelectricity is documented for Ho-member, which is absent for Nd. Our
+investigation establishes dominating 4d(Ru)-4f(R) magnetic correlation in this
+series for the heavier R-members.",1910.02204v1
+2020-01-17,Single-layer graphene on epitaxial FeRh thin films,"Graphene is a 2D material that displays excellent electronic transport
+properties with prospective applications in many fields. Inducing and
+controlling magnetism in the graphene layer, for instance by proximity of
+magnetic materials, may enable its utilization in spintronic devices. This
+paper presents fabrication and detailed characterization of single-layer
+graphene formed on the surface of epitaxial FeRh thin films. The magnetic state
+of the FeRh surface can be controlled by temperature, magnetic field or strain
+due to interconnected order parameters. Characterization of graphene layers by
+X-ray Photoemission and X-ray Absorption Spectroscopy, Low-Energy Ion
+Scattering, Scanning Tunneling Microscopy, and Low-Energy Electron Microscopy
+shows that graphene is single-layer, polycrystalline and covers more than 97%
+of the substrate. Graphene displays several preferential orientations on the
+FeRh(001) surface with unit vectors of graphene rotated by 30{\deg}, 15{\deg},
+11{\deg}, and 19{\deg} with respect to FeRh substrate unit vectors. In
+addition, the graphene layer is capable to protect the films from oxidation
+when exposed to air for several months. Therefore, it can be also used as a
+protective layer during fabrication of magnetic elements or as an atomically
+thin spacer, which enables incorporation of switchable magnetic layers within
+stacks of 2D materials in advanced devices.",2001.06559v1
+2020-04-23,Correlation-driven eightfold magnetic anisotropy in a two-dimensional oxide monolayer,"Engineering magnetic anisotropy in two-dimensional systems has enormous
+scientific and technological implications. The uniaxial anisotropy universally
+exhibited by two-dimensional magnets has only two stable spin directions,
+demanding 180 degrees spin switching between states. We demonstrate a novel
+eightfold anisotropy in magnetic SrRuO3 monolayers by inducing a spin
+reorientation in (SrRuO3)1/(SrTiO3)N superlattices, in which the magnetic easy
+axis of Ru spins is transformed from uniaxial <001> direction (N = 1 and 2) to
+eightfold <111> directions (N = 3, 4 and 5). This eightfold anisotropy enables
+71 and 109 degrees spin switching in SrRuO3 monolayers, analogous to 71 and 109
+degrees polarization switching in ferroelectric BiFeO3. First-principle
+calculations reveal that increasing the SrTiO3 layer thickness induces an
+emergent correlation-driven orbital ordering, tuning spin-orbit interactions
+and reorienting the SrRuO3 monolayer easy axis. Our work demonstrates that
+correlation effects can be exploited to substantially change spin-orbit
+interactions, stabilizing unprecedented properties in two-dimensional magnets
+and opening rich opportunities for low-power, multi-state device applications.",2004.10939v1
+2020-12-21,Electronic correlations and magnetic interactions in infinite-layer NdNiO$_2$,"The large antiferromagnetic exchange coupling in the parent high-$T_{\rm c}$
+cuprate superconductors is believed to play a crucial role in pairing the
+superconducting carriers. The recent observation of superconductivity in
+hole-doped infinite-layer (IL-) NdNiO$_2$ brings to the fore the relevance of
+magnetic coupling in high-$T_{\rm c}$ superconductors, particularly because no
+magnetic ordering is observed in the undoped IL-NdNiO$_2$ unlike in parent
+copper oxides. Here, we investigate the electronic structure and the nature of
+magnetic exchange in IL-NdNiO$_2$ using state-of-the-art many-body quantum
+chemistry methods. From a systematic comparison of the electronic and magnetic
+properties with isostructural cuprate IL-CaCuO$_2$, we find that the on-site
+dynamical correlations are significantly stronger in IL-NdNiO$_2$ compared to
+the cuprate analog. These dynamical correlations play a critical role in the
+magnetic exchange resulting in an unexpectedly large antiferromagnetic nearest
+neighbor isotropic $J$ of 77 meV between the Ni$^{1+}$ ions within the
+$ab$-plane. While we find many similarities in the electronic structure between
+the nickelate and the cuprate, the role of electronic correlations is
+profoundly different in the two. We further discuss the implications of our
+findings in understanding the origin of superconductivity in nickelates.",2012.11179v1
+2018-03-05,Dipolar-coupled moment correlations in clusters of magnetic nanoparticles,"Here, we investigate the nature of the moment coupling between 10-nm
+DMSA-coated magnetic nanoparticles, in both colloidal dispersion and in powder
+form. The individual iron oxide cores were composed of > 95% maghemite and
+agglomerated to clusters. At room temperature the ensemble behaved as a
+superparamagnet according to M\""ossbauer and magnetization measurements,
+however, with clear signs of dipolar interactions at low temperatures. Analysis
+of temperature-dependent AC susceptibility data in the superparamagnetic regime
+indicates a tendency for dipolar coupled anticorrelations of the core moments
+within the clusters. To resolve the directional correlations between the
+particle moments we performed polarized small-angle neutron scattering and
+determined the magnetic spin-flip cross-section of the powder in low magnetic
+field at 300 K. We extract the underlying pair distance distribution function
+of the magnetization vector field by an indirect Fourier transform of the
+cross-section, and which suggests positive as well as negative correlations
+between nearest neighbor moments, with anticorrelations clearly dominating for
+next-nearest moments. These tendencies are confirmed by Monte Carlo simulations
+of such core-clusters.",1803.01747v2
+2018-07-03,Electronic structure depiction of magnetic origin in BaTiO$_{3-δ}$ thin film: A combined experimental and first-principles based investigation,"With the motive of unraveling the origin of native vacancy induced
+magnetization in ferroelectric perovskite oxide systems, here we explore the
+consequences of electronic structure modification in magnetic ordering of
+oxygen deficient epitaxial BaTiO$_{3-\delta}$ thin films. Our adapted
+methodology employs state-of-the-art experimental approaches viz.
+photo-emission, photo-absorption spectroscopies, magnetometric measurements
+duly combined with first principles based theoretical methods within the frame
+work of density functional theory (DFT and DFT+\textit{U}) calculations. Oxygen
+vacancy (O$ _{V} $) is observed leading partial population of Ti 3\textit{d}
+(t$_{2g}$), which induces defect state in electronic structure near the Fermi
+level and reduces the band gap. The oxygen deficient BaTiO$_{2.75} $ film
+reveals Mott-Hubbard insulator characteristic, in contrast to the band gap
+insulating nature of the stoichiometric BaTiO$ _{3}$. The observed magnetic
+ordering is attributed to the asymmetric distribution of spin polarized charge
+density in the vicinity of O$ _{V} $ site which originates unequal magnetic
+moment values at first and second nearest neighboring Ti sites, respectively.
+Hereby, we present an exclusive method for maneuvering the band gap and on-site
+electron correlation energy with consequences on magnetic properties of
+BaTiO$_{3-\delta}$ system, which can open a gateway for designing novel single
+phase multiferroic system.",1807.01214v2
+2019-02-12,High Quality Factor High-Temperature Superconducting Microwave Cavity Development for the Dark Matter Axion Search in a Strong Magnetic Field,"We demonstrate a superconducting (SC) microwave (mw) cavity that can
+accelerate the dark matter search by maintaining superconductivity in a high DC
+magnetic field. We used high-temperature superconductor (HTSC) yttrium barium
+copper oxide (YBCO) with a phase transition temperature of 90K to prevent SC
+failure by the magnetic field. Since the direct deposition of HTSC film on the
+metallic mw cavity is very difficult, we used the commercial HTSC tapes which
+are flexible metallic tapes coated with HTSC thin films. We fabricated
+resonating cavity ($f_{TM010}$ ~ 6.89 GHz) with a third of the inner wall
+covered by YBCO tapes and measured the quality factor (Q factor) at 4K
+temperature, varying the DC magnetic field from 0 to 8 tesla. There was no
+significant quality (Q) factor drop and the superconductivity was well
+maintained even in 8 tesla magnetic field. This implies the possibility of good
+performance of HTSC mw resonant cavity under a strong magnetic field for axion
+detection.",1902.04551v3
+2019-11-08,Effect of strain on magnetic and orbital ordering of LaSrCrO$_3$/LaSrMnO$_3$ heterostructures,"We investigate the effect of strain and film thickness on the orbital and
+magnetic properties of LaSrCrO$_3$ (LSCO)/LaSrMnO$_3$ (LSMO) heterostructures
+using bulk magnetometry, soft X-ray magnetic spectroscopy, first-principles
+density functional theory, high-resolution electron microscopy and X-ray
+diffraction. We observe an anti-parallel ordering of the magnetic moments
+between the ferromagnetic LSMO layers and the LSCO spacers leading to a
+strain-independent ferromagnetic ground state of the LSCO/LSMO heterostructures
+for LSMO layers as thin as 2 unit cells. As the LSMO thickness is increased, a
+net ferromagnetic state is maintained, however, the average magnetic moment per
+Mn is found to be dependent on the magnitude of the substrate-induced strain.
+The differences in the magnetic responses are related to preferential
+occupation of the Mn $x^2-y^2$ (in-plane) d-orbitals for tensile strain and
+$3z^2-r^2$ (out-of-plane) orbitals under compressive strain leading to
+competing ferromagnetic and anti-ferromagnetic exchange interactions within the
+LSMO layers. These results underscore the relative contributions of orbital,
+structural and spin degree of freedom and their tunability in atomically-thin
+crystalline complex oxide layers.",1911.03007v2
+2020-11-13,Cell dynamics simulations of coupled charge and magnetic phase transformation in correlated oxides,"We present a comprehensive numerical study on the kinetics of phase
+transition that is characterized by two non-conserved scalar order parameters
+coupled by a special linear-quadratic interaction. This particular
+Ginzburg-Landau theory has been proposed to describe the coupled charge- and
+magnetic transition in nickelates and the collinear stripe phase in cuprates.
+The inhomogeneous state of such systems at low temperatures consists of
+magnetic domains separated by quasi-metallic domain-walls where the
+charge-order is reduced. By performing large-scale cell dynamics simulations,
+we find a two-stage phase-ordering process in which a short period of
+independent evolution of the two order parameters is followed by a correlated
+coarsening process. The long-time growth and coarsening of magnetic domains is
+shown to follow the Allen-Cahn power law. We further show that the
+nucleation-and-growth dynamics during phase transformation to the ordered
+states is well described by the Kolmogorov-Johnson-Mehl-Avrami theory in two
+dimensions. On the other hand, the presence of quasi-metallic magnetic domain
+walls in the ordered states gives rise to a very different kinetics for phase
+transition to the high temperature paramagnetic phase. In this new scenario,
+the phase transformation is initiated by the decay of magnetic domain walls
+into two insulator-metal boundaries, which subsequently move away from each
+other. Implications of our findings to recent nano-imaging experiments on
+nickelates are also discussed.",2011.07045v2
+2021-02-22,Single Harmonic-based Narrowband Magnetic Particle Imaging,"Visualization of the in vivo spatial distribution of superparamagnetic iron
+oxide nanoparticles (SPIONs) is crucial to biomedicine. Magnetic particle
+imaging (MPI) is one of the most promising approaches for direct measurements
+of the SPION distribution. In this paper, we systematically investigate a
+single-harmonic-based narrowband MPI approach. Herein, only the 3rd harmonic at
+15 kHz of the SPION signal induced in an excitation magnetic field of 5 kHz is
+measured via a narrowband detection system for imaging during scanning a
+field-free-point in a field of view. Experiments on spot and line phantoms are
+performed to evaluate the spatial distribution by the assessment of the full
+width at half maximum and modulation transfer function at different excitation
+magnetic fields from 4 to 10 mT. Experimental results demonstrate that
+reconstructed images have a spatial resolution of 1.6 and 1.5 mm for a gradient
+field of 2.2 T/m and 4.4 T/m in x- and z-direction, respectively, at an
+excitation magnetic field of 4 mT. In terms of line gap, two lines with a gap
+of 0.5 mm are resolved. With increasing the excitation magnetic field to 10 mT,
+the spatial resolution gets worse to 2.4 and 2.0 mm in x- and z-direction,
+respectively. Moreover, the custom-built MPI scanner allows a limit of
+detection of 53 microgram (Fe)/mL (500 ng Fe weight) using perimag SPIONs. In
+addition, the excellent performance is demonstrated by imaging experiments on
+an ""emg"" logo phantom. We believe that the proposed narrowband MPI approach is
+a promising approach for SPION imaging.",2102.10954v1
+2021-03-10,Finite transverse conductance and anisotropic magnetoconductance under an applied in-plane magnetic field in two-dimensional electron gases with strong spin-orbit coupling,"The current in response to a bias in certain two-dimensional electron gas
+(2DEG), can have a nonzero transverse component under a finite magnetic field
+applied in the plane where electrons are confined. This phenomenon known as
+planar Hall effect is accompanied by dependencies of both the longitudinal and
+the transverse components of the current on the angle $\phi$ between the bias
+direction and the magnetic field. In 2DEG with spin orbit coupling (SOC) such
+as oxide interfaces, this effect has been experimentally witnessed. Further, a
+fourfold oscillation in longitudinal resistance as a function of $\phi$ has
+also been observed. Motivated by these, we perform scattering theory
+calculations on a 2DEG with SOC in presence of an in-plane magnetic field
+connected to two dimensional leads on either sides to obtain longitudinal and
+transverse conductances. We find that the longitudinal conductance is
+$\pi$-periodic and the transverse conductance is $2\pi$-periodic in $\phi$. The
+magnitude of oscillation in transverse conductance with $\phi$ is enhanced in
+certain patches in $(\alpha,b)$-plane where $\alpha$ is the strength of SOC and
+$b$ is Zeeman energy due to magnetic field. The oscillation in transverse
+conductance with $\phi$ can be highly multi-fold for large values of $\alpha$
+and $b$. The highly multi-fold oscillations of transverse conductance are due
+to Fabry-P\'erot type interference between the modes in the central region as
+backed by its length dependent features. Our study establishes that SOC in a
+material is sufficient to observe planar Hall effect without the need for
+anisotropic magnetic ordering or nontrivial topology of the bandstructure.",2103.05901v2
+2021-04-05,Anisotropic Triangular Lattice Realized in Rhenium Oxychlorides A3ReO5Cl2 (A = Ba and Sr),"We report the synthesis, crystal structure, and magnetic properties of two
+new quantum antiferromagnets A3ReO5Cl2 (A = Sr and Ba). The crystal structure
+is isostructural with the mineral pinalite Pb3WO5Cl2, in which the Re6+ ion is
+square-pyramidally coordinated by five oxide atoms, and forms an anisotropic
+triangular lattice (ATL) made of S = 1/2 spins. The magnetic interactions J and
+J' in the ATL are estimated from magnetic susceptibilities to be 19.5 (44.9)
+and 9.2 (19.3) K, respectively, with J'/J = 0.47 (0.43) for A = Ba (Sr). For
+each compound, heat capacity at low temperatures shows a large T-linear
+component with no signature of long-range magnetic order above 2 K, which
+suggests a gapless spin liquid state of one-dimensional character of the J
+chains in spite of the significantly large J' couplings. This is a consequence
+of one-dimensionalization by geometrical frustration in the ATL magnet; a
+similar phenomenon has been observed in two compounds with slightly smaller
+J'/J values: Cs2CuCl4 (J'/J = 0.3) and the related compound Ca3ReO5Cl2 (0.32).
+Our findings demonstrate that 5d mixed-anion compounds provide a unique
+opportunity to explore novel quantum magnetism.",2104.01838v1
+2021-07-24,Anomalous Nernst thermopower and giant magnetostriction in microwave synthesized La0.5Sr0.5CoO3,"Ferromagnetic metallic oxides have potential applications in spincaloric
+devices which utilize the spin property of charge carriers for interconversion
+of heat and electricity through the spin Seebeck or the anomalous Nernst effect
+or both. In this work, we synthesized polycrystalline La0.5S0.5CoO3 by
+microwave irradiation method and studied its transverse thermoelectric voltage
+(Nernst thermopower) and change in the linear dimension of the sample (Joule
+magnetostriction) in response to external magnetic fields. In addition,
+magnetization, temperature dependences of electrical resistivity, and
+longitudinal Seebeck coefficient (Sxx) in absence of an external magnetic field
+were also measured. The sample is ferromagnetic with a Curie temperature of TC
+= 247 K and shows a metal-like resistivity above and below TC with a negative
+sign of Sxx suggesting charge transport due to electrons. Magnetic field
+dependence of the Nernst thermopower (Sxy) at a fixed temperature shows a rapid
+increase at low fields and a tendency to saturate at high fields as like the
+magnetization. Anomalous contribution to Sxy was extracted from total Sxy
+measured and it exhibits a maximum value of ~ 0.21 microV/K at 180 K for H = 50
+kOe, which is comparable to the value found in a single crystal for a lower Sr
+content. The Joule magnetostriction is positive, i.e., the length of the sample
+expands along the direction of the magnetic field and it does not saturate even
+at 50 kOe. The magnetostriction increases with decreasing temperature below TC
+and reaches a maximum value of 500 ppm at T = 40 K and below. Coexistence of
+the anomalous Nernst thermopower and giant magnetostriction in a single
+compound has potential applications for thermal energy harvesting and
+low-temperature actuators, respectively.",2107.11535v1
+2021-09-05,Cooperative control of perpendicular magnetic anisotropy via crystal structure and orientation in single-crystal flexible SrRuO3 membranes,"Flexible magnetic materials with robust and controllable perpendicular
+magnetic anisotropy (PMA) are highly desirable for developing flexible
+high-performance spintronic devices. However, it is still challenge to
+fabricate PMA films through current techniques of direct deposition on
+polymers. Here, we report a facile method for synthesizing single-crystal
+freestanding SrRuO3 (SRO) membranes with controlled crystal structure and
+orientation using water-soluble Ca3-xSrxAl2O6 sacrificial layers. Through
+cooperative effect of crystal structure and orientation engineering, flexible
+SrRuO3 membranes reveal highly tunable magnetic anisotropy from in-plane to
+our-of-plane with a remarkable PMA energy of 7.34*106 erg/cm3. Based on the
+first-principles calculations, it reveals that the underlying mechanism of PMA
+modulation is intimately correlated with structure-controlled Ru 4d-orbital
+occupation, as well as the spin-orbital matrix element differences, dependent
+on the crystal orientation. In addition, there are no obvious changes of the
+magnetism after 10,000 bending cycles, indicating an excellent magnetism
+reliability in the prepared films. This work provides a feasible approach to
+prepare the flexible oxide films with strong and controllable PMA.",2109.02061v1
+2022-09-24,Magnetic nature of wolframite MgReO$_4$,"Rhenium oxides belonging to the family $A$ReO$_4$ where $A$ is a metal
+cation, exhibit interesting electronic and magnetic properties. In this study
+we have utilized the muon spin rotation/relaxation ($\mu^+$SR) technique to
+study the magnetic properties of the MgReO$_4$ compound. To the best of our
+knowledge, this is the first investigation reported on this interesting
+material, that is stabilized in a wolframite crystal structure using a special
+high-pressure synthesis technique. Bulk magnetic studies show the onset of an
+antiferromagnetic (AF) long range order, or a possible singlet spin state at
+$T_{\rm C1}\approx90$~K, with a subtle second high-temperature transition at
+$T_{\rm C2}\approx280$~K. Both transitions are also confirmed by heat capacity
+($C_p$) measurements. From our $\mu^+$SR measurements, it is clear that the
+sample enters an AF order below $T_{\rm C1}=T_{\rm N}\approx85$~K. We find no
+evidence of magnetic signal above $T_{\rm N}$, which indicates that $T_{\rm
+C2}$ is likely linked to a structural transition. Further, via sensitive zero
+field (ZF) $\mu^+$SR measurements we find evidence of a spin reorientation at
+$T_{\rm Cant}\approx65$~K. This points towards a transition from a collinear AF
+into a canted AF order at low temperature, which is proposed to be driven by
+competing magnetic interactions.",2209.11966v1
+2023-03-25,Type-II antiferromagnetic ordering in double perovskite oxide Sr$_2$NiWO$_6$,"Magnetic double perovskite compounds provide a fertile playground to explore
+interesting electronic and magnetic properties. By complementary macroscopic
+characterizations, neutron powder diffraction measurements and first-principles
+calculations, we have performed comprehensive studies on the magnetic ordering
+in the double perovskite compound Sr$_2$NiWO$_6$. It is found by neutron
+diffraction to order magnetically in a collinear type-II antiferromagnetic
+structure in a tetragonal lattice with $k$ = (0.5, 0, 0.5) below $T\rm_N$ = 56
+K. In the ground state, the ordered moment of the spin-1 Ni$^{2+}$ ions is
+determined to be 1.9(2) $\mu\rm_{B}$, indicating a significant quenching of the
+orbital moment. The Ni$^{2+}$ moments in Sr$_2$NiWO$_6$ are revealed to cant
+off the $c$ axis by 29.2$^{\circ}$, which is well supported by the
+first-principles magnetic anisotropy energy calculations. Furthermore, the
+in-plane and out-of-plane next-nearest-neighbor superexchange couplings
+($J\rm_2$ and $J\rm_{2c}$) are found to play a dominant role in the spin
+Hamiltonian of Sr$_2$NiWO$_6$, which accounts for the stabilization of the
+type-II AFM structure as its magnetic ground state.",2303.14370v2
+2023-07-26,Establishing Magnetic Coupling in Spin-crossover-2D Hybrid Nanostructures via Interfacial Charge-transfer Interaction,"Despite a clear demonstration of bistability in spin-crossover (SCO)
+materials, the absence of long-range magnetic order and poor electrical
+conductivity limit their prospect in spintronic and nanoelectronic
+applications. Intending to create hybrid devices made of spin-crossover
+(SCO)-2D architecture, here, we report an easily processable Fe-based SCO
+nanostructures grown on 2D reduced graphene oxide (rGO). The heterostructure
+shows enhanced cooperativity due to formation of interfacial charge transfer
+induced inter-molecular interaction. The spin transition temperature is
+controlled by tuning the coverage area of SCO nanostructured networks over the
+2D surfaces, thus manipulating hysteresis (aka memory) of the heterostructure.
+The enhanced magnetic coupling of the heterostructure leads to the spontaneous
+magnetization states with a large coercive field of $\sim$ 3000 Oe.
+Additionally, the low conductivity of the pristine SCO nanostructures is
+addressed by encapsulating them on suitable 2D rGO template, enabling detection
+of magnetic bistable spin states during high-spin/low-spin conductance change.
+This adds spin functionality in conductance switching for realizing hybrid 2D
+spintronic devices. Ab-inito calculations, on the experimentally proposed
+nanostructures, corroborate the enhanced magnetic interaction in the proposed
+architecture facilitated by interfacial charge transfer and provide insights on
+the microscopic mechanism.",2307.14135v1
+2023-11-22,Engineering magnetic domain wall energies in multiferroic BiFeO$_3$ via epitaxial strain,"Epitaxial strain has emerged as a powerful tool to tune magnetic and
+ferroelectric properties in functional materials such as in multiferroic
+perovskite oxides. Here, we use first-principles calculations to explore the
+evolution of magnetic interactions in the antiferromagnetic multiferroic
+BiFeO$_3$ (BFO), one of the most promising multiferroics for future technology.
+The epitaxial strain in BFO(001) oriented film is varied between
+$\varepsilon_{xx,yy}$ $\in$ $[-2\%, +2\%]$. We find that both strengths of the
+exchange interaction and Dzyaloshinskii-Moriya interaction (DMI) decrease
+linearly from compressive to tensile strain whereas the uniaxial
+magnetocrystalline anisotropy follows a parabolic behavior which lifts the
+energy degeneracy of the (111) easy plane of bulk BFO. From the trends of the
+magnetic interactions we can explain the destruction of cycloidal order in
+compressive strain as observed in experiments due to the increasing anisotropy
+energy. For tensile strain, we predict that the ground state remains unchanged
+as a function of strain. By using the domain wall (DW) energy, we envision the
+region where isolated chiral magnetic texture might occur as function of strain
+i.e. where the DW and the spin spiral energy are equal. This transition between
+$-1.5\%$ and $-0.5\%$ of strain should allow topologically stable magnetic
+states such as antiferromagnetic skyrmions and merons to occur. Hence, our work
+should trigger experimental and theoretical investigations in this range of
+strain.",2311.13215v1
+1995-05-26,Specific Heat of YBa$_2$Cu$_3$O$_{7 - {\rm δ}}$ Single Crystals: Implications for the Vortex Structure,"The anisotropy of the magnetic field dependence of the specific heat of
+YBa$_2$Cu$_3$O$_{7 - {\rm \delta}}$ can be used to identify different
+low-energy excitations, which include phonons, spin-$ \frac{1}{2}$ particles,
+and electronic contributions. With a magnetic field H applied perpendicular to
+the copper oxide planes, we find that the specific heat includes a linear-T
+term proportional to $\sqrt{H}$. The nonlinear field dependence of the density
+of states at the Fermi level suggests that there are quasiparticle excitations
+throughout the entire vortex, not just in the vortex core. The $\sqrt{H} T$
+term agrees quantitatively with G. Volovik's prediction for a superconductor
+with lines of nodes in the gap. A similar, but much smaller, effect is
+predicted for fields parallel to the planes, and sensitive measurements of the
+in-plane anisotropic magnetic field dependence of the specific heat could be
+used to map out the nodes.",9505129v1
+1996-03-15,Effect of non-magnetic impurities on the gap of a $d_{x^2-y^2}$ superconductor as seen by angle-resolved photoemission,"An analysis of angle-resolved photoemission (ARPES) experiments in the
+superconducting state of the high \tc copper-oxides is presented. It is based
+on a phenomenological weak-coupling BCS model which incorporates the
+experimental normal state dispersion extracted from ARPES, and non-magnetic
+impurity scattering in the presence of a $d_{x^2-y^2}$ order parameter (OP). It
+is shown, that already in the pure case, the broadening by finite momentum
+resolution of the analyzer leads to a finite region of apparent `gaplessness'
+around the true node of the OP. Non-magnetic impurities further amplify this
+effect by introducing additional spectral weight around zero frequency. At
+sufficiently large impurity concentrations $n_i\approx 0.02-0.05$, this results
+in an extended region of `gaplessness' up to $\delta\phi=\pm7$ ($\phi$ the
+angle on the Fermi surface) around the true node for a large range of moderate
+to strong impurity potential strengths. Different ways to identify the presence
+of impurity scattering in the ARPES spectra are proposed.",9603117v1
+1998-11-25,Quantum Oscillations and Overcritical Torque Interaction in Sr2RuO4,"Sr2RuO4 is the only known layered perovskite oxide superconductor without
+copper; there is strong evidence for an unconventional (""p-wave"") pairing
+mechanism, and it has recently been shown to possess a cylindrical,
+""quasi-two-dimensional"" Fermi surface. Using Sr2RuO4 as a test case for the
+detection of quantum oscillations with piezoresistive microcantilevers, the
+piezolever torque magnetometry technique was successfully implemented on a
+dilution refrigerator. It was possible to reproduce the quantum-oscillatory
+magnetization data on all three Fermi surface sheets, in a crystal of microgram
+mass. Moreover, an absolute estimate of the amplitude of the oscillation is
+provided. We also investigated the phenomenon of torque interaction which
+distorts the magnetization signal and introduces harmonics and sidebands to the
+dHvA spectrum. As the torque interaction effect grows in strength,
+overcriticality is shown to lead to discrete magnetization jumps and to a
+near-asymptotically damped ""sproing"" effect.",9811364v1
+2000-03-18,Inhomogeneity-Induced Superconductivity?,"A t-J-like model for inhomogeneous superconductivity of cuprate oxides is
+presented, in which local anisotropic magnetic terms are essential. We show
+that this model predicts pairing, consistent with experiments, and argue how
+the macroscopic phase-coherent state gradually grows upon lowering of the
+temperature. We show that appropriate inhomogeneities are essential in order to
+have significant pair binding in the thermodynamic limit. Particularly, {\it
+local} breaking of SU(2) spin symmetry is an efficient mechanism for inducing
+pairing of two holes, as well as explaining the magnetic scattering properties.
+We also discuss the connection of the resulting inhomogeneity-induced
+superconductivity to recent experimental evidence for a linear relation between
+magnetic incommensurability and the superconducting transition temperature, as
+a function of doping.",0003321v1
+2000-03-29,Static and dynamic spin correlations in the spin-glass phase of slightly-doped La_{2-x}Sr_xCuO_4,"Neutron scattering experiments reveal that a diagonal spin modulation, which
+is a one-dimensional modulation rotated away by 45$^\circ$ from that in the
+superconducting phase, occurs universally across the insulating spin-glass
+phase in La$_{2-x}$Sr$_x$CuO$_4$ (0.02$\le x\le$0.055). This establishes an
+intimate relation between the magnetism and the transport properties in the
+high-temperature copper oxide superconductors. Furthermore, it is found that
+the charge density per unit length estimated using a charge stripe model is
+almost constant throughout the phase diagram, even when the modulation rotates
+away by 45$^\circ$ at the superconducting boundary. However, at the lowest
+values for $x$ the density changes approaching 1 hole/Cu as in
+La$_{2-x}$Sr$_x$NiO$_4$. Magnetic excitation spectra suggest that magnetic
+correlations change from incommensurate to commensurate at $\omega\sim$7 meV
+and $T\sim$70 K, indicating a characteristic energy for the incommensurate
+structure of 6-7 meV.",0003466v2
+2000-09-07,Coulomb interaction in oxygen \textit{p}-shell in LDA+U method and its influence on calculated spectral and magnetic properties of transition metal oxides,"Coulomb interaction between electrons on p-orbitals of oxygen atom in
+strongly correlated compounds is not negligible, since its value (U_p) has
+comparable order of magnitude with the value of Coulomb interaction on
+d-orbitals of transition metal atom (U_d). We investigate the effect of taking
+into account Coulomb correlations in oxygen p-shell in addition to the
+correlations in the transition metal d-shell in frame of the LDA+U method. Our
+calculations for NiO, MnO and La2CuO4 show that this additional correction in
+general improves the agreement with experimental data for the spectral (energy
+gap values, relative position of the main peaks in X-ray photoemission
+spectroscopy (XPS) and Bremsstrahlung isohromate spectroscopy (BIS)) and
+magnetic properties (magnetic moment values and intersite exchange interaction
+parameters values).",0009107v1
+2002-02-15,Non-volatile magnetoresistive memory in phase separated La$_{0.325}$Pr$_{0.300}$Ca$_{0.375}$MnO$_3$,"We have measured magnetic and transport response on the polycrystalline
+La$_{5/8-y}$Pr$_y$Ca$_{3/8}$MnO$_3$ ($y=0.30$, average grain size 2 microns)
+compound. In the temperature range where ferromagnetic metallic and insulating
+regions coexist we observed a persistent memory of low magnetic fields ($<$ 1
+T) which is determined by the actual amount of the ferromagnetic phase. The
+possibility to manipulate this fraction with relatively small external
+perturbations is related to the phase separated nature of these manganese oxide
+based compounds. The colossal magnetoresistance figures obtained (about 80%)
+are determined by the fraction enlargement mechanism. Self-shielding of the
+memory to external fields is found under certain described circumstances. We
+show that this non-volatile memory has multilevel capability associated with
+different applied low magnetic field values.",0202261v1
+2002-07-16,High-T_{c} Superconductors with AF Order: Limitations on Spin-Fluctuation Pairing Mechanism,"The very intriguing antagonistic interplay of antiferromagnetism (AF) and
+superconductivity (SC), recently discovered in high-temperature
+superconductors, is studied in the framework of a microscopic theory. We
+explain the surprisingly large increase of the magnetic Bragg peak intensity
+$I_{Q}$ at $Q\sim (\pi ,\pi)$ in the magnetic field $H\ll H_{c2}$ at low
+temperatures $0<T\ll T_{c},T_{AF}$ in $La_{2-x}Sr_{x}CuO_{4}$. Good agreement
+with experimental results is found. The theory predicts large anisotropy of the
+relative intensity $R_{Q}(H)=(I_{Q}(H)-I_{Q}(0))/I_{Q}(0)$%, i.e.
+$R_{Q}(H\parallel c-axis)\gg R_{Q}(H\perp c-axis)$. The quantum (T=0) phase
+diagram at H=0 is constructed. The theory also predicts: (i) the magnetic field
+induced AF order in the SC state; (ii) small value for the spin-fluctuation
+coupling constant $g<(0.025-0.05)$ $eV$. The latter gives very small SC
+critical temperature $T_{c}(\ll 40$ $K)$, thus questioning the spin-fluctuation
+mechanism of pairing in HTS oxides.",0207400v2
+2002-10-28,"Structure, electric and magnetic properties of the electron-doped manganese oxide: La{sub(1-x)}Te{sub(x)}MnO{sub(3)}(x=0.1, 0.15)","In this letter, the electrical and magnetic properties of
+La{sub(1-x)}Te{sub(x)}MnO{sub(3)}(x=0.1, 0.15), which is a new material and
+shows good colossal magnetoresistance (CMR) behavior, have been investigated.
+These compounds have rhombohedral structure. In this materical, Te replaced a
+part of La ions, which induced the lattice cell constriction and Mn-O-Mn bond
+angle widening. X-ray photoemission spectroscopy (XPS) measurement revealed
+that the Te ions were in the tetravalent state and the manganese ions could be
+considered as in a mixture state of Mn{sup(2+)} and Mn{Sup(3+)}. Thus the
+material could be viewed as an electron-doped compound. The Curie temperature
+(Tc) was about 240 K and 255 K for x=0.1, 0.15, respectively. The maximum
+magnetoresistance ratio MR=[r(0)-r(H)]/r(0) was about 51% at 200 K and in the
+applied magnetic field of 40 kOe.",0210609v2
+2003-09-30,"Structural and magnetic anomalies among the spin-chain compounds, Ca3Co1+xIr1-xO6","The results of x-ray diffraction, and ac and dc magnetization as a function
+of temperature are reported for a new class of spin-chain oxides,
+Ca3Co1+xIr1-xO6. While the x= 0.0, 0.3, 0.5 and 1.0 are found to form in the
+K4CdCl6-derived rhombhohedral (space group R-3c) structure, the x= 0.7
+composition is found to undergo a monoclinic distortion in contrast to a
+literature report. Apparently, the change in the crystal symmetry with x
+manifests itself as a change in the sign of paramagnetic Curie temperature for
+this composition as though magnetic coupling sensitively depends on such
+crystallographic distortions. All the compositions exhibit spin-glass anomalies
+with an unusually large frequency dependence of the peak temperature in ac
+susceptibility in a temperature range below 50 K, interestingly obeying
+Voger-Fulcher relationship even for the stoichiometric compounds.",0309700v1
+2004-02-25,High-transition-temperature superconductivity in the absence of the magnetic-resonance mode,"The fundamental mechanism that gives rise to high-transition-temperature
+(high-Tc) superconductivity in the copper oxide materials has been debated
+since the discovery of the phenomenon. Recent work has focussed on a sharp
+'kink' in the kinetic energy spectra of the electrons as a possible signature
+of the force that creates the superconducting state. The kink has been related
+to a magnetic resonance and also to phonons. Here we report that infrared
+spectra of Bi2Sr2CaCu2O(8+d), (Bi-2212) show that this sharp feature can be
+separated from a broad background and, interestingly, weakens with doping
+before disappearing completely at a critical doping level of 0.23 holes per
+copper atom. Superconductivity is still strong in terms of the transition
+temperature (Tc approx 55 K), so our results rule out both the magnetic
+resonance peak and phonons as the principal cause of high-Tc superconductivity.
+The broad background, on the other hand, is a universal property of the copper
+oxygen plane and a good candidate for the 'glue' that binds the electrons.",0402612v1
+2004-03-01,Mass-Enhanced Fermi Liquid Ground State in Na$_{1.5}$Co$_2$O$_4$,"Magnetic, transport, and specific heat measurements have been performed on
+layered metallic oxide Na$_{1.5}$Co$_2$O$_4$ as a function of temperature $T$.
+Below a characteristic temperature $T^*$=30$-$40 K, electrical resistivity
+shows a metallic conductivity with a $T^2$ behavior and magnetic susceptibility
+deviates from the Curie-Weiss behavior showing a broad peak at $\sim$14 K. The
+electronic specific heat coefficient $\gamma$ is $\sim$60 mJ/molK$^2$ at 2 K.
+No evidence for magnetic ordering is found. These behaviors suggest the
+formation of mass-enhanced Fermi liquid ground state analogous to that in
+$d$-electron heavy fermion compound LiV$_2$O$_4$.",0403028v1
+2004-03-10,Structural and magnetic properties of a series of low doped Zn$_{1-x}$Co$_x$O thin films deposited from Zn and Co metal targets on (0001) Al$_2$O$_3$ substrates,"We report on the synthesis of low doping Zn$_{1-x}$Co$_x$O ($0<x<0.1$) thin
+films on (0001)-Al$_2$O$_3$ substrates. The films were prepared in an oxidizing
+atmosphere, using the pulsed laser deposition technique starting from Zn and Co
+metallic targets. We first studied the influence of the strains of ZnO and
+their stuctural properties. Second, we have investigated the structural and the
+magnetic properties of the Zn$_{1-x}$Co$_x$O films. We show that at low doping,
+the lattice parameters and the magnetization of the Zn$_{1-x}$Co$_x$O films
+depend strongly on the Co concentration.",0403281v1
+2004-03-12,Decoupling of orbital and spin degrees of freedom in Li1-xNaxNiO2,"In the Li1-xNaxNiO2 solid solutions three different single phase regions
+exist: for x > 0.9, forx = 0.7 and for x < 0.3. Although the intermediate
+compound does not show the cooperative Jahn-Teller transition of NaNiO2, its
+magnetic properties remain very similar with, in particular, the low
+temperature 3D magnetic ordering. Therefore, the strong coupling between
+orbital and spindegrees of freedom, characteristic of other oxides like
+perovskites, and usually invoked to explainthe absence of both long-range
+orbital and magnetic ordering in LiNiO2, seems not to take placein these
+layered compounds with 90-degree bonds. We also discuss the relevance of the O
+crystal fieldsplitting induced by the trigonal distortion, in generating AFM
+Ni-Ni in-plane interactions.",0403329v2
+2004-06-22,A-site Randomness Effect on Structural and Physical Properties of Ba-based Perovskite Manganites,"The discovery of novel structural and physical properties in the $A$-site
+ordered manganite $R$BaMn$_{2}$O$_{6}$ ($R$ = Y and rare earth elements) has
+demanded new comprehension about perovskite manganese oxides. In the present
+study, the $A$-site disordered form, $R_{0.5}$Ba$_{0.5}$MnO$_{3}$, has been
+investigated and compared with both $R$BaMn$_{2}$O$_{6}$ and
+$R_{0.5}A_{0.5}$MnO$_{3}$ ($A$: Sr, Ca) in the structures and electromagnetic
+properties. $R_{0.5}$Ba$_{0.5}$MnO$_{3}$ has a primitive cubic perovskite cell
+in the structure and magnetic glassy states are dominant as its ground state,
+in contrast to the ordinary disordered $R_{0.5}A_{0.5}$MnO$_{3}$ ($A$: Sr, Ca).
+In Pr-compounds with various degrees of Pr/Ba randomness at the $A$-sites, the
+$A$-site disorder gradually suppresses both ferromagnetic and A-type
+antiferromagnetic transitions and finally leads to a magnetic glassy state in
+Pr$_{0.5}$Ba$_{0.5}$MnO$_{3}$. A peculiar behavior, multi-step magnetization
+and resistivity change, has been observed in Pr$_{0.5}$Ba$_{0.5}$MnO$_{3}$.
+These properties could be closely related to any spatial heterogeneity caused
+by the random distribution of Ba$^{2 +}$ and $R^{3 +}$ with much different
+ionic radius.",0406505v1
+2004-07-16,Strong Room-Temperature Ferromagnetism in Co2+-Doped TiO2 made from Colloidal Nanocrystals,"Colloidal cobalt-doped TiO2 (anatase) nanocrystals were synthesized and
+studied by electronic absorption, magnetic circular dichroism, transmission
+electron microscopy, magnetic susceptibility, cobalt K-shell X-ray absorption
+spectroscopy, and extended X-ray absorption fine structure measurements. The
+nanocrystals were paramagnetic when isolated by surface-passivating ligands,
+weakly ferromagnetic (Ms = 1.5 x 10-3 mB/Co2+ at 300 K) when aggregated, and
+strongly ferromagnetic (up to Ms = 1.9 mB/Co2+ at 300 K) when spin-coated into
+nanocrystalline films. X-ray absorption data reveal that cobalt is in the Co2+
+oxidation state in all samples. In addition to providing strong experimental
+support for the existence of intrinsic ferromagnetism in cobalt-doped TiO2,
+these results demonstrate the possibility of using colloidal TiO2 diluted
+magnetic semiconductor nanocrystals as building blocks for assembly of
+ferromagnetic semiconductor nanostructures with potential spintronics
+applications.",0407451v1
+2004-08-13,Insulator-metal transition and the magnetic phase diagram of La1-xTexMnO3,"The structural, electrical transport and magnetic properties of perovskite
+oxides La1-xTexMnO3 have been investigated and thus the magnetic phase diagram
+of La1-xTexMnO3 compounds as a function of temperature and the doping level x
+has been obtained. All samples have rhombohedral structure and undergo
+paramagnetic-ferromagnetic (PM-FM) transition accompanied with metal-insulator
+transition (MIT). Whereas a charge ordering (CO) transition begins to appear at
+for the sample with x=0.60. Moreover, the variation of the Curie temperature
+and the MIT temperature is quite complex and the results are discussed in terms
+of three factors including the average A-site cation radius <rA>, the size
+mismatch and the Te content. In addition, there has an evident
+magnetoresistance (MR) at low temperatures for all samples.",0408307v1
+2004-11-26,Electronic band structure of alfa-(Per)2M(mnt)2 compounds,"The band structure of alfa-(Per)2M(mnt)2, leads to a description of these
+materials as nearly perfectly one dimensional conductors. The conduction is
+mainly along the stacking direction of the partially oxidized perylene
+molecules, (Per)1/2+, with virtually no interchain bandwidth. However, recent
+high magnetic field experiments suggest orbital coupling of the magnetic field
+to the electronic structure, indicating a finite interchain bandwidth. The
+details of the band structure and the possible variances, at low energies, from
+a perfect one dimensional system are examined. In particular, multiple
+quasi-one dimensional Fermi surface sheets, which would become important at low
+temperatures, may lead to an explanation for the experimental finding of a
+magnetic field induced high field charge density wave ground state.
+Experimental tests to observe the effects of the finite interchain bandwidth
+are proposed.",0411676v2
+2005-04-15,"Competition between ferromagnetism and spin glass: the key for large magnetoresistance in oxygen deficient perovskites SrCo1-xMxO3-d (M = Nb, Ru)","The magnetic and magnetotransport properties of the oxygen deficient
+perovskites, SrCo1-xMxO3-d with M = Nb and Ru, were investigated. Both Nb- and
+Ru-substituted cobaltites are weak ferromagnets, with transition temperatures
+Tm of 130-150 K and 130-180 K, respectively, and both exhibit a spin glass
+behavior at temperatures below Tf = 80-90 K. It is demonstrated that there
+exists a strong competition between ferromagnetism and spin glass state, where
+Co4+ induces ferromagnetism, whereas Nb or Ru substitution at the cobalt sites
+induces magnetic disorder, and this particular magnetic behavior is the origin
+of large negative magnetoresistance of these oxides, reaching up to 30% at 5 K
+in 7 T. The differences between Nb- and Ru-substituted cobaltites are discussed
+on the basis of the different electronic configuration of niobium and ruthenium
+cations.",0504379v1
+2005-09-05,Magnetoelectric Coupling in epsilon-Fe2O3,"Nanoparticles of the ferrimagnetic epsilon-Fe2O3 oxide have been synthesized
+by sol-gel method. Here, we report on the measurements of the dielectric
+permittivity as a function of temperature, frequency and magnetic field. It is
+found that, coinciding with the transition from collinear ferrimagnetic
+ordering to an incommensurate magnetic state occurring at about 100 K, there is
+an abrupt change (about 30 %) of permittivity suggesting the existence of a
+magnetoelectric coupling in this material. Indeed, magnetic field dependent
+measurements at 100 K have revealed an increase of the permittivity by about
+0.3 % in 6 T. Prospective advantages of epsilon-Fe2O3 as multiferroic material
+are discussed.",0509104v1
+2005-10-02,Orbital order and fluctuations in Mott insulators,"Basic mechanisms controlling orbital order and orbital fluctuations in
+transition metal oxides are discussed. The lattice driven classical orbital
+picture, e.g. like in manganites LaMnO$_3$, is contrasted to the quantum
+behavior of orbitals in frustrated superexchange models as realised in
+pseudocubic titanites ATiO$_3$ and vanadates AVO$_3$. In YVO$_3$, the lattice
+and superexchange effects strongly compete -- this explains the extreme
+sensitivity of magnetic states to temperature and doping. Lifting the $t_{2g}$
+orbital degeneracy by a relativistic spin-orbital coupling is considered on
+example of the layered cobaltates. We find that the spin-orbital mixing of
+low-energy states leads to unusual magnetic correlations in a triangular
+lattice of the CoO$_2$ parent compound. Finally, the magnetism of sodium-rich
+compounds Na$_{1-x}$CoO$_2$ is discussed in terms of a spin/orbital polaronic
+liquid.",0510025v2
+2006-01-24,Magnetic and Metal-Insulator Transitions in beta-Na0.5CoO2 and gamma-K0.5CoO2 -NMR and Neutron Diffraction Studies-,"Co-oxides beta-Na0.5CoO2 and gamma-K0.5CoO2 have been prepared by the Na
+de-intercalation from alpha-NaCoO2 and by the floating-zone method,
+respectively. It has been found that successive phase transitions take place at
+temperatures Tc1 and Tc2 in both systems. The appearance of the internal
+magnetic field at Tc1 with decreasing temperature T indicates that the
+antiferromagnetic order exists at T < Tc1, as in gamma-Na0.5CoO2. For
+beta-Na0.5CoO2, the transition temperatures and the NMR parameters determined
+from the data taken for magnetically ordered state are similar to those of
+gamma-Na0.5CoO2, indicating that the difference of the stacking ways of the
+CoO2 layers between these systems do not significantly affect their physical
+properties. For gamma-K0.5CoO2, the quantitative difference of the physical
+quantities are found from those of beta- and gamma-Na0.5CoO2. The difference
+between the values of Tci (i = 1 and 2) of these systems might be explained by
+considering the distance between CoO2 layers.",0601538v1
+2006-02-27,"Relating supercooling and glass-like arrest of kinetics for phase separated systems: studies on doped CeFe$_2$ and (La,Pr,Ca)MnO$_3$","Coexisting ferromagnetic and antiferromagnetic phases over a range of
+temperature as well as magnetic field have been reported in many materials of
+current interest, showing disorder-broadened 1st order transitions. Anomalous
+history effects observed in magnetization and resistivity are being explained
+invoking the concepts of kinetic arrest akin to glass transitions. From
+magnetization measurements traversing novel paths in field-temperature space,
+we obtain the intriguing result that the regions of the sample which can be
+supercooled to lower temperatures undergo kinetic-arrest at higher
+temperatures, and vice versa. Our results are for two diverse systems viz. the
+inter-metallic doped CeFe$_2$ which has an antiferromagnetic ground state, and
+the oxide La-Pr-Ca-Mn-O which has a ferromagnetic ground state, indicating the
+possible universality of this effect of disorder on the widely encountered
+phenomenon of glass-like arrest of kinetics.",0602627v1
+2006-03-24,Structural and magneto-transport characterization of Co_2Cr_xFe_(1-x)Al Heusler alloy films,"We investigate the structure and magneto-transport properties of thin films
+of the Co_2Cr_xFe_(1-x)Al full-Heusler compound, which is predicted to be a
+half-metal by first-principles theoretical calculations. Thin films are
+deposited by magnetron sputtering at room temperature on various substrates in
+order to tune the growth from polycrystalline on thermally oxidized Si
+substrates to highly textured and even epitaxial on MgO(001) substrates,
+respectively. Our Heusler films are magnetically very soft and ferromagnetic
+with Curie temperatures up to 630 K. The total magnetic moment is reduced
+compared to the theoretical bulk value, but still comparable to values reported
+for films grown at elevated temperature. Polycrystalline Heusler films combined
+with MgO barriers are incorporated into magnetic tunnel junctions and yield 37%
+magnetoresistance at room temperature.",0603649v1
+2006-03-31,Pinhole and tunneling conduction channels superimposed in magnetic tunnel junction: results and inferences,"The influence of ballistic channels superimposed on tunneling conduction
+channels in magnetic tunnel junctions has been studied in a manganese oxide
+based tunneling device. Inversion of magnetoresistance has been observed in
+magnetic tunnel junctions with pinhole nanocontacts over a broad temperature
+range. The tunnel magnetoresistance undergoes a change of sign at higher bias
+and temperature. This phenomenon is attributed to the parallel conduction
+channels consisting of spin conserved ballistic transport through the pinhole
+contact where the transmission probability is close to unity and spin polarized
+tunneling across the insulating spacer with weak transmittivity. The results
+seem to resolve a controversy regarding ballistic magnetoresistance in
+ferromagnetic nanocontacts and establishes that ballistic magnetoresistance do
+exist even if the previous results are attributed to magnetostriction and
+magnetostatic force related artifacts.",0603843v1
+2006-06-16,Unravelling the origin of the controversial magnetic properties of BiFeO3 thin films,"Single phase (001)-oriented BiFeO3 (BFO) thin films grown by pulsed laser
+deposition can only be obtained in a narrow window of deposition pressure and
+temperature and have a low magnetic moment. Out of the stability window Fe- or
+Bi-rich impurity phases form, which has a strong impact on the physical and
+structural properties of the films, even for impurity concentrations hardly
+detectable by standard X-ray diffraction measurements. By using more sensitive
+tools such as X-Ray absorption spectroscopy and X-ray magnetic circular
+dichroism and performing advanced X-ray diffraction characterization, we show
+that in non-optimal conditions Fe forms ferrimagnetic gamma-Fe2O3 precipitates
+that are responsible for virtually all the ferromagnetic signal measured on
+such BFO films by standard magnetometry. This confirms that the BFO phase has a
+very low intrinsic moment that does not depend on strain. We also study the
+influence of film thickness on the nucleation of parasitic phases and find that
+epitaxial strain can stabilize the pure BFO phase in slightly over-oxidizing
+growth conditions.",0606441v1
+2006-12-18,Crystallographically oriented magnetic ZnFe2O4 nanoparticles synthesized by Fe implantation into ZnO,"In this paper, a correlation between structural and magnetic properties of Fe
+implanted ZnO is presented. High fluence Fe^+ implantation into ZnO leads to
+the formation of superparamagnetic alpha-Fe nanoparticles. High vacuum
+annealing at 823 K results in the growth of alpha-Fe particles, but the
+annealing at 1073 K oxidized the majority of the Fe nanoparticles. After a long
+term annealing at 1073 K, crystallographically oriented ZnFe2O4 nanoparticles
+were formed inside ZnO with the orientation relationship of
+ZnFe2O4(111)[110]//ZnO(0001)[1120]. These ZnFe2O4 nanoparticles show a
+hysteretic behavior upon magnetization reversal at 5 K.",0612444v1
+2006-10-23,Integrated Cell Manipulation Systems,"A new type of microfluidic system for biological cell manipulation, a
+CMOS/microfluidic hybrid, is demonstrated. The hybrid system starts with a
+custom-designed CMOS (complementary metal-oxide semiconductor) chip fabricated
+in a semiconductor foundry using standard integration circuit technology. A
+microfluidic channel is post-fabricated on top of the CMOS chip to provide
+biocompatible environment. The motion of individual biological cells that are
+tagged with magnetic beads is directly controlled by the CMOS chip that
+generates localized magnetic filed patterns using an on-chip array of
+micro-electromagnets. The speed and the programmability of the CMOS chip
+further allow for the dynamic reconfiguration of the magnetic fields,
+substantially increasing the manipulation capability of the hybrid system. The
+concept of a hybrid system is verified by simultaneously manipulating
+individual biological cells with microscopic resolution. A new operation
+protocol that exploits the fast speed of electronics to trap and move a large
+number of cells with less power consumption is also demonstrated. Combining the
+advantages of microelectronics, the CMOS/microfluidic hybrid approach presents
+a new model for a multifunctional lab-on-a chip for biological and medical
+applications.",0610043v1
+2007-04-10,Coupling between magnetic ordering and structural instabilities in perovskite biferroics: A first-principles study,"We use first-principles density functional theory-based calculations to
+investigate structural instabilities in the high symmetry cubic perovskite
+structure of rare-earth (R $=$ La, Y, Lu) and Bi-based biferroic chromites,
+focusing on $\Gamma$ and $R$ point phonons of states with para-, ferro-, and
+antiferromagnetic ordering. We find that (a) the structure with G-type
+antiferromagnetic ordering is most stable, (b) the most dominant structural
+instabilities in these oxides are the ones associated with rotations of oxygen
+octahedra, and (c) structural instabilities involving changes in Cr-O-Cr bond
+angle depend sensitively on the changes in magnetic ordering. The dependence of
+structural instabilities on magnetic ordering can be understood in terms of how
+super-exchange interactions depend on the Cr-O-Cr bond angles and Cr-O bond
+lengths. We demonstrate how adequate buckling of Cr-O-Cr chains can favour
+ferromagnetism. Born effective charges (BEC) calculated using the Berry phase
+expression are found to be anomalously large for the A-cations, indicating
+their chemical relevance to ferroelectric distortions.",0704.1251v1
+2007-04-14,Evidence for nonmonotonic magnetic field penetration in a type-I superconductor,"Polarized neutron reflectometry (PNR) provides evidence that nonlocal
+electrodynamics governs the magnetic field penetration in an extreme low-k
+superconductor. The sample is an indium film with a large elastic mean free
+path (11 mkm) deposited on a silicon oxide wafer. It is shown that PNR can
+resolve the difference between the reflected neutron spin asymmetries predicted
+by the local and nonlocal theories of superconductivity. The experimental data
+support the nonlocal theory, which predicts a nonmonotonic decay of the
+magnetic field.",0704.1872v2
+2007-06-14,Carrier-mediated magnetoelectricity in complex oxide heterostructures,"While tremendous success has been achieved to date in creating both single
+phase and composite magnetoelectric materials, the quintessential
+electric-field control of magnetism remains elusive. In this work, we
+demonstrate a linear magnetoelectric effect which arises from a novel
+carrier-mediated mechanism, and is a universal feature of the interface between
+a dielectric and a spin-polarized metal. Using first-principles density
+functional calculations, we illustrate this effect at the SrRuO$_3$/SrTiO$_3$
+interface and describe its origin. To formally quantify the magnetic response
+of such an interface to an applied electric field, we introduce and define the
+concept of spin capacitance. In addition to its magnetoelectric and spin
+capacitive behavior, the interface displays a spatial coexistence of magnetism
+and dielectric polarization suggesting a route to a new type of interfacial
+multiferroic.",0706.2199v1
+2007-06-19,Tunneling spectroscopy of persistent currents in superconducting microrings,"It is shown that in a structure consisting of a superconducting ring-shaped
+electrode overlapped by a normal metal contact through a thin oxide barrier,
+measurements of the tunnel current in magnetic field can probe persistent
+currents in the ring. The effect manifests itself as periodic oscillations of
+the tunnel current through the junction at a fixed bias voltage as function of
+perpendicular magnetic field. The magnitude of oscillations depends on bias
+point. It reaches maximum at energy eV which is close to the superconducting
+gap and decreases with increase of temperature. The period of oscillations dF
+in units of magnetic flux is equal neither to h/e nor to h/2e, but
+significantly exceeds these values for larger loop circumferences. The
+phenomenon is explained by formation of metastable states with large vorticity.
+The pairing potential and the superconducting density of states are
+periodically modulated by the persistent currents at sub-critical values
+resulting in corresponding variations of the measured tunnel current.",0706.2776v1
+2007-10-12,First-principles prediction of coexistence of magnetism and ferroelectricity in rhombohedral Bi2FeTiO6,"First principles calculations based on the density functional theory within
+the local spin density approximation plus U(LSDA+U)scheme, show rhombohedral
+Bi$_2$FeTiO$_6$ is a potential multiferroic in which the magnetism and
+ferroelectricity coexist . A ferromagnetic configuration with magnetic moment
+of 4 $\mu_B$ per formula unit have been reported with respect to the minimum
+total energy. Spontaneous polarization of 27.3 $\mu$ C/cm$^2$, caused mainly by
+the ferroelectric distortions of Ti, was evaluated using the berry phase
+approach in the modern theory of polarization. The Bi-6s stereochemical
+activity of long-pair and the `d$^0$-ness' criterion in off-centring of Ti were
+coexisting in the predicted new system. In view of the oxidation state of
+Bi$^{3+}$,Fe$^{2+}$,Ti$^{4+}$, and O$^{2-}$ from the orbital-resolved density
+of states of the Bi-6p, Fe-3d,Ti-3d, and O-2p states,the valence state of
+Bi$_2$FeTiO$_6$ in the rhombohedral phase was found to be
+Bi$_2$$^{3+}$Fe$^{2+}$Ti$^{4+}$O$_6$.",0710.2391v1
+2007-10-19,Magnetism and structure of LixCoO2 and comparison to NaxCoO2,"The magnetic properties and structure of LixCoO2 for x between 0.5 and 1.0
+are reported. Co4+ is found to be high-spin in LixCoO2 for x between 0.94 and
+1.0 and low-spin for x between 0.50 and 0.78. Weak antiferromagnetic coupling
+is observed, increasing in strength as more Co4+ is introduced. At an x value
+of about 0.65, the temperature-independent contribution to the magnetic
+susceptibility and the electronic contribution to the specific heat are
+largest. Neutron diffraction analysis reveals that the lithium oxide layer
+expands perpendicular to the basal plane and the Li ions displace from their
+ideal octahedral sites with decreasing x. A comparison of the structures of the
+NaxCoO2 and LixCoO2 systems reveals that the CoO2 layer changes substantially
+with alkali content in the former but is relatively rigid in the latter.
+Further, the CoO6 octahedra in LixCoO2 are less distorted than those in
+NaxCoO2. We postulate that these structural differences strongly influence the
+physical properties in the two systems.",0710.3767v1
+2008-06-10,Image charge screening: a new approach to enhance magnetic ordering temperatures,"We have tested the concept of image charge screening as a new approach to
+enhance magnetic ordering temperatures and superexchange interactions in ultra
+thin films. Using a 3 monolayer NiO(100) film grown on Ag(100) and an
+identically thin film on MgO(100) as model systems, we observed that the Neel
+temperature of the NiO film on the highly polarizable metal substrate is 390 K
+while that of the film on the poorly polarizable insulator substrate is below
+40 K. This demonstrates that screening by highly polarizable media may point to
+a practical way towards designing strongly correlated oxide nanostructures with
+greatly improved magnetic properties.",0806.1710v1
+2008-10-05,Structural and magnetic properties of an InGaAs/Fe$_3$Si superlattice in cylindrical geometry,"The structure and the magnetic properties of an InGaAs/Fe3Si superlattice in
+a cylindrical geometry are investigated by electron microscopy techniques,
+x-ray diffraction and magnetometry. To form a radial superlattice, a
+pseudomorphic InGaAs/Fe3As bilayer has been released from its substrate
+self-forming into a rolled-up microtube. Oxide-free interfaces as well as areas
+of crystalline bonding are observed and an overall lattice mismatch between
+succeeding layers is determined. The cylindrical symmetry of the final radial
+superlattice shows a significant effect on the magnetization behavior of the
+rolled-up layers.",0810.0835v2
+2008-10-13,"Synthesis, crystal structure and spin-density-wave anomaly of the iron arsenide-fluoride SrFeAsF","The new quaternary iron arsenide-fluoride SrFeAsF with the tetragonal
+ZrCuSiAs-type structure was synthesized and the crystal structure was
+determined by X-ray powder diffraction (P4/nmm, a = 399.30(1), c = 895.46(1)
+pm). SrFeAsF undergoes a structural and magnetic phase transition at 175 K,
+accompanied by strong anomalies in the specific heat, electrical resistance and
+magnetic susceptibility. In the course of this transition, the space group
+symmetry changes from tetragonal (P4/nmm) to orthorhombic (Cmme). 57Fe
+Moessbauer spectroscopy experiments show a single signal at room temperature at
+an isomer shift of 0.30(1) mm/s and magnetic hyperfine-field splitting below
+the phase transition temperature. Our results clearly show that SrFeAsF
+exhibits a spin density wave (SDW) anomaly at 175 K very similar to LaFeAsO,
+the parent compound of the iron arsenide-oxide superconductors and thus SrFeAsF
+may serve as a further parent compound for oxygen-free iron arsenide
+superconductors.",0810.2120v1
+2009-02-06,Na ordering imprints a metallic kagome lattice onto the Co planes of Na2/3CoO2,"We report $^{23}$Na and $^{59}$Co nuclear magnetic (NMR) and quadrupolar
+resonance (NQR) studies for the $x=2/3$ phase of the lamellar oxide
+Na$_{x}$CoO$_{2}$, which allowed us to establish reliably the atomic order of
+the Na layers and their stacking between the CoO$_{2}$ slabs. We evidence that
+the Na$^{+}$ order stabilizes filled non magnetic Co$^{3+}$ ions on 25% of the
+cobalt sites arranged in a triangular sublattice. The transferred holes are
+delocalized on the 75% complementary cobalt sites which unexpectedly display a
+planar cobalt kagom\'{e} structure. These experimental results resolve a
+puzzling issue by precluding localized moments pictures for the magnetic
+properties. They establish that the quasi ferromagnetic properties result from
+a narrow band connecting a frustrated arrangement of atomic orbitals, and open
+the route to unravel through similar studies the electronic properties of the
+diverse ordered phases of sodium cobaltates.",0902.1108v1
+2009-05-12,Considerations on the symmetry of loop order in cuprates,"The loop-current state discovered in the pseudogap phase of cuprates breaks
+time reversal symmetry and lowers the point group symmetry of the crystal. The
+order parameter and the magnetic structure within each unit cell which is
+associated with it can be described by a toroidal moment parallel to the
+copper-oxide planes. We discuss lattice point group symmetry of the magnetic
+structure. As an application, we discuss a few effects that necessarily
+accompany order parameter in the pseudogap phase. The magnitude estimated for
+these specific effects makes them hard to observe because they rely on the
+small magnetic fields associated with the order parameter. Effects, associated
+with the electronic energies are much larger. Some of them have already been
+discussed.",0905.1987v3
+2009-11-10,Co-doped Ceria: Tendency towards ferromagnetism driven by oxygen vacancies,"We perform an electronic structure study for cerium oxide homogeneously-doped
+with cobalt impurities, focusing on the role played by oxygen vacancies and
+structural relaxation. By means of full-potential ab-initio methods, we explore
+the possibility of ferromagnetism as observed in recent experiments. Our
+results indicate that oxygen vacancies seem to be crucial for the appearance of
+a ferromagnetic alignment among Co impurities, obtaining an increasing tendency
+towards ferromagnetism with growing vacancy concentration. The estimated
+couplings cannot explain though, the experimentally observed room-temperature
+ferromagnetism. In this systematic study, we draw relevant conclusions
+regarding the location of the oxygen vacancies and the magnetic couplings
+involved. In particular, we find that oxygen vacancies tend to nucleate in the
+neighborhood of Co impurities and we get a remarkably strong ferromagnetic
+coupling between Co atoms and the Ce^{3+} neighboring ions. The calculated
+magnetic moments per cell depend on the degree of reduction which could explain
+the wide spread in the magnetization values observed in the experiments.",0911.1959v1
+2010-03-11,"Magnetic and Electrical Properties of Ordered 112-type Perovskite LnBaCoMnO5+δ(Ln = Nd, Eu)","Investigation of the oxygen-deficient 112-type ordered oxides of the type
+LnBaCoMnO5+\delta (Ln = Nd, Eu) evidences certain unusual magnetic behavior at
+low temperatures, compared to the LnBaCo2O5+\delta cobaltites. One observes
+that the substitution of manganese for cobalt suppresses the ferromagnetic
+state and induces strong antiferromagnetic interactions. Importantly,
+NdBaCoMnO5.9 depicts a clear paramagnetic to antiferromagnetic type transition
+around 220 K, whereas for EuBaCoMnO5.7 one observes an unusual magnetic
+behavior below 177 K which consists of ferromagnetic regions embedded in an
+antiferromagnetic matrix. The existence of two sorts of crystallographic sites
+for Co/Mn and their mixed valence states favor the ferromagnetic interaction
+whereas antiferromagnetism originates from the Co3+-O-Co3+ and Mn4+-O-Mn4+
+interactions. Unlike the parent compounds, the present Mn-substituted phases do
+not exhibit prominent magnetoresistance effects in the temperature range
+75-400K.",1003.2262v1
+2010-06-04,Low-temperature ferromagnetism in a weakly doped Hubbard magnet,"In the framework of the diagrammatic method with self-consistent field, the
+maximum on the temperature dependence of the susceptibility of a weakly doped
+narrow-band Hubbard magnet below the Curie temperature $T_{\rm C}$ is
+predicted. By numerical calculations, it is proved that it appears at small
+hole concentrations $n_{h}$. In this case, the temperature dependence of the
+magnetization $M$($T$) has a typical Fermi-like shape with the point of
+inflection at a temperature $T_{\rm inf}$. The approximate solution of the
+system of equations for the mean spin and the chemical potential gives the
+Schottky susceptibility typical of a two-level system with a gap of order of
+$n_{h}(1-n_{h})W$, where W is the bandwidth. This behavior reflects the
+existence of two subbands with up- and down-spins. It may be observed
+experimentally in the surface layers of oxide metal nanoparticles with narrow
+bands and a weak oxygen nonstoichiometry.",1006.0907v1
+2010-07-01,ZnO:Co Diluted Magnetic Semiconductor or Hybrid Nanostructure for Spintronics?,"We have studied the influence of intrinsic and extrinsic defects in the
+magnetic and electrical transport properties of Co-doped ZnO thin films. X ray
+absorption measurements show that Co substitute Zn in the ZnO structure and it
+is in the 2+ oxidation state. Magnetization (M) measurements show that doped
+samples are mainly paramagnetic. From M vs. H loops measured at 5 K we found
+that the values of the orbital L and spin S numbers are between 1 and 1.3 for L
+and S = 3/2, in agreement with the representative values for isolated Co 2+.
+The obtained negative values of the Curie-Weiss temperatures indicate the
+existence of antiferromagnetic interactions between transition metal atoms.",1007.0269v1
+2010-08-10,On the resistivity at low temperatures in electron-doped cuprate superconductors,"We measured the magnetoresistance as a function of temperature down to 20mK
+and magnetic field for a set of underdoped PrCeCuO (x=0.12) thin films with
+controlled oxygen content. This allows us to access the edge of the
+superconducting dome on the underdoped side. The sheet resistance increases
+with increasing oxygen content whereas the superconducting transition
+temperature is steadily decreasing down to zero. Upon applying various magnetic
+fields to suppress superconductivity we found that the sheet resistance
+increases when the temperature is lowered. It saturates at very low
+temperatures. These results, along with the magnetoresistance, cannot be
+described in the context of zero temperature two dimensional
+superconductor-to-insulator transition nor as a simple Kondo effect due to
+scattering off spins in the copper-oxide planes. We conjecture that due to the
+proximity to an antiferromagnetic phase magnetic droplets are induced. This
+results in negative magnetoresistance and in an upturn in the resistivity.",1008.1682v1
+2010-12-02,Electronic structure and magnetism of transition metal doped Zn12O12 clusters: Role of defects,"We present a comprehensive study of the energetics and magnetic properties of
+ZnO clusters doped with 3d transition metals (TM) using ab initio density
+functional calculations in the framework of generalized gradient approximation
++ Hubbard U (GGA+U) method. Our results within GGA+U for all 3d dopants except
+Ti indicate that antiferromagnetic interaction dominates in a neutral,
+defect-free cluster. Formation energies are calculated to identify the stable
+defects in the ZnO cluster. We have analyzed in details the role of these
+defects to stabilize ferromagnetism when the cluster is doped with Mn, Fe, and
+Co. Our calculations reveal that in the presence of charged defects the
+transition metal atoms residing at the surface of the cluster may have an
+unusual oxidation state, that plays an important role to render the cluster
+ferromagnetic. Defect induced magnetism in ZnO clusters without any TM dopants
+is also analyzed. These results on ZnO clusters may have significant
+contributions in the nanoengineering of defects to achieve desired
+ferromagnetic properties for spintronic applications.",1012.0430v1
+2010-12-14,Scaling behavior of the spin pumping effect in ferromagnet/platinum bilayers,"We systematically measured the DC voltage V_ISH induced by spin pumping
+together with the inverse spin Hall effect in ferromagnet/platinum bilayer
+films. In all our samples, comprising ferromagnetic 3d transition metals,
+Heusler compounds, ferrite spinel oxides, and magnetic semiconductors, V_ISH
+invariably has the same polarity. V_ISH furthermore scales with the
+magnetization precession cone angle with a universal prefactor, irrespective of
+the magnetic properties, the charge carrier transport mechanism or type. These
+findings quantitatively corroborate the present theoretical understanding of
+spin pumping in combination with the inverse spin Hall effect.",1012.3017v2
+2011-01-05,"Non-thermal laser induced precession of magnetization in ferromagnetic semiconductor (Ga,Mn)As","Non-thermal laser induced spin excitations, recently discovered in
+conventional oxide and metal ferromagnets, open unprecedented opportunities for
+research and applications of ultrafast optical manipulation of magnetic
+systems. Ferromagnetic semiconductors, and (Ga,Mn)As in particular, should
+represent ideal systems for exploring this new field. Remarkably, the presence
+of non-thermal effects has remained one of the outstanding unresolved problems
+in the research of ferromagnetic semiconductors to date. Here we demonstrate
+that coherent magnetization dynamics can be excited in (Ga,Mn)As non-thermally
+by a transfer of angular momentum from circularly polarized femtosecond laser
+pulses and by a combination of non-thermal and thermal effects due to a
+transfer of energy from laser pulses. The thermal effects can be completely
+suppressed in piezo-electrically controlled samples. Our work is based on
+pump-and-probe measurements in a large set of (Ga,Mn)As epilayers and on
+systematic analysis of circular and linear magneto-optical coefficients. We
+provide microscopic theoretical interpretation of the experimental results.",1101.1049v1
+2011-01-10,A story of high-temperature ferromagnetism in semiconductors,"The comprehensive search for multifunctional materials has resulted in the
+discovery of semiconductors and oxides showing ferromagnetic features
+persisting to room temperature. In this tutorial review the methods of
+synthesis of these materials, as well as the application of element-specific
+nano-analytic tools, particularly involving synchrotron radiation and electron
+microscopy, are described and shown to reveal the presence of nano-scale phase
+separations. Various means to control the aggregation of magnetic cations are
+discussed together with the mechanisms accounting for ferromagnetism of either
+condensed or diluted magnetic semiconductors. Finally, the question of whether
+high temperature ferromagnetism is possible in semiconductors not containing
+magnetic ions is touched upon.",1101.1981v1
+2011-01-31,Template assisted self-assembly of individual and clusters of magnetic nanoparticles,"The deliberate control over the spatial arrangement of nanostructures is the
+desired goal for many applications as e.g. in data storage, plasmonics or
+sensor arrays. Here we present a novel method to assist the self-assembly
+process of magnetic nanoparticles. The method makes use of nanostructured
+aluminum templates obtained after anodization of aluminum disks and the
+subsequent growth and removal of the newly formed alumina layer, resulting in a
+regular honeycomb type array of hexagonally shaped valleys. The iron oxide
+nanoparticles, 20 nm in diameter, are spin coated onto the nanostructured
+templates. Depending on the size, each hexagon site can host up to 30
+nanoparticles. These nanoparticles form clusters of different arrangements
+within the valleys, such as collars, chains, and hexagonally closed islands.
+Ultimately, it is possible to isolate individual nanoparticles. The strengths
+of magnetic interaction between particles in a cluster is probed using the
+memory effect known from the coupled state in superspin glass systems.",1101.5899v1
+2011-06-29,Highly spin-polarized conducting state at the interface between non-magnetic band insulators: LaAlO3/FeS2 (001),"First-principles density functional calculations demonstrate that a
+spin-polarized two-dimensional conducting state can be realized at the
+interface between two non-magnetic band insulators. The (001) surface of the
+diamagnetic insulator FeS2 (pyrite) supports a localized surface state deriving
+from Fe d-orbitals near the conduction band minimum. The deposition of a few
+unit cells of the polar perovskite oxide LaAlO3 leads to electron transfer into
+these surface bands, thereby creating a conducting interface. The occupation of
+these narrow bands leads to an exchange splitting between the spin sub-bands,
+yielding a highly spin-polarized conducting state distinct from the rest of the
+non-magnetic, insulating bulk. Such an interface presents intriguing
+possibilities for spintronics applications.",1106.6010v1
+2011-08-23,Resonant X-Ray Diffraction Study of Strongly Spin-Orbit-Coupled Mott Insulator CaIrO3,"We performed resonant x-ray diffraction experiments at the $L$ absorption
+edges for the post-perovskite-type compound CaIrO$_{3}$ with $(t_{2g})^5$
+electronic configuration. By observing the magnetic signals, we could clearly
+see that the magnetic structure was a striped order with an antiferromagnetic
+moment along the c-axis and that the wavefunction of a $t_{2g}$ hole is
+strongly spin-orbit entangled, the $J_{\rm eff} =1/2$ state. The observed spin
+arrangement is consistent with theoretical work predicting a unique
+superexchange interaction in the $J_{\rm eff} =1/2$ state and points to the
+universal importance of the spin-orbit coupling in Ir oxides, irrespective of
+the local coordination and lattice topology. We also propose that the
+non-magnetic resonant scattering is a powerful tool for unraveling an orbital
+state even in a metallic iridate.",1108.4523v1
+2011-08-24,In vitro toxicity and uptake of magnetic nanorods,"In this paper we investigate the internalization and cytotoxicity of
+nanostructured materials having the form of elongated rods, with diameter of
+200 nm and lengths 1 - 10 {\mu}m. The rods were made from the controlled
+aggregation of sub-10 nm iron oxide nanoparticles. Recently, we have shown that
+the nanorods inherited the superparamagnetic property of the particles. These
+rods can actually be moved by the application of an external magnetic field.
+Here we evaluate the in vitro toxicity of the magnetic nanorods by using MTT
+assays on NIH/3T3 mouse fibroblasts. The toxicity assays revealed that the
+nanorods are biocompatible, as exposed cells remained 100% viable relative to
+controls over a period of a few days. Optical microscopy allow to visualize the
+rods inside the cells and to determine their number per cell. Roughly 1/3 of
+the total incubated rods were uptaken by the fibroblasts.",1108.4773v1
+2012-02-07,Magnetically driven metal-insulator transition in NaOsO3,"The metal-insulator transition (MIT) is one of the most dramatic
+manifestations of electron correlations in materials. Various mechanisms
+producing MITs have been extensively considered, including the Mott (electron
+localization via Coulomb repulsion), Anderson (localization via disorder) and
+Peierls (localization via distortion of a periodic 1D lattice). One additional
+route to a MIT proposed by Slater, in which long-range magnetic order in a
+three dimensional system drives the MIT, has received relatively little
+attention. Using neutron and X-ray scattering we show that the MIT in NaOsO3 is
+coincident with the onset of long-range commensurate three dimensional magnetic
+order. Whilst candidate materials have been suggested, our experimental
+methodology allows the first definitive demonstration of the long predicted
+Slater MIT. We discuss our results in the light of recent reports of a Mott
+spin-orbit insulating state in other 5d oxides.",1202.1482v1
+2012-02-09,Observation of Huge Magnetoresistance and Multiferroic-like Behavior of Co Nanoparticles in a C60 matrix,"Tunneling magnetoresistance (TMR) via oxides or molecules includes fruitful
+physics, such as spin filtering and hybridized interface states, in addition to
+various practical applications using large TMR ratio at room temperature. Then,
+a larger TMR effect with a new fundamental physics is awaited because further
+progress on spintronics can be realized. Here we report a discovery of a
+gigantic TMR ratio of 1,400,000% in a C60-Co nanocomposite spin device. The
+observed effect is induced by a combination of a Coulomb blockade effect and a
+novel magnetic switching effect. Theoretical investigation reveals that an
+electric field and a magnetic field control the magnetization and the
+electronic charging state, respectively, of the Co nanoparticles as in physics
+of multiferroicity.",1202.1920v3
+2012-08-10,Magnetic structural change of Sr2IrO4 upon Mn doping,"The layered 5d transition metal oxide Sr2IrO4 has been shown to host a novel
+Jeff=1/2 Mott spin orbit insulating state with antiferromagnetic ordering,
+leading to comparisons with the layered cuprates. Here we study the effect of
+substituting Mn for Ir in single crystals of Sr2Ir0.9Mn0.1O4 through an
+investigation involving bulk measurements and resonant x-ray and neutron
+scattering. We observe a new long range magnetic structure emerge upon doping
+through a reordering of the spins from the basal plane to the c-axis with a
+reduced ordering temperature compared to Sr2IrO4. The strong enhancement of the
+magnetic x-ray scattering intensity at the L3 edge relative to the L2 edge
+indicates that the Jeff=1/2 state is robust and capable of hosting a variety of
+ground states.",1208.2229v2
+2012-11-27,Magnetic Insulator-Induced Proximity Effects in Graphene: Spin Filtering and Exchange Splitting Gaps,"We report on first-principles calculations of spin-dependent properties in
+graphene induced by its interaction with a nearby magnetic insulator (Europium
+oxide, EuO). The magnetic proximity effect results in spin polarization of
+graphene $\pi$ orbitals by up to 24 %, together with large exchange splitting
+bandgap of about 36 meV. The position of the Dirac cone is further shown to
+depend strongly on the graphene-EuO interlayer. These findings point towards
+the possible engineering of spin gating by proximity effect at relatively high
+temperature, which stands as a hallmark for future all-spin information
+processing technologies.",1211.6377v1
+2012-12-24,Robustness of basal-plane antiferromagnetic order and the $J_{eff}=1/2$ state in single-layer iridate spin-orbit Mott insulators,"The magnetic structure and electronic groundstate of the layered perovskite
+Ba2IrO4 have been investigated using x-ray resonant magnetic scattering (XRMS).
+Our results are compared with those for Sr2IrO4, for which we provide
+supplementary data on its magnetic structure. We find that the dominant,
+long-range antiferromagnetic order is remarkably similar in the two compounds,
+and that the electronic groundstate in Ba2IrO4, deduced from an investigation
+of the XRMS $L_3/L_2$ intensity ratio, is consistent with a $J_{eff}=1/2$
+description. The robustness of these two key electronic properties to the
+considerable structural differences between the Ba and Sr analogues is
+discussed in terms of the enhanced role of the spin-orbit interaction in 5d
+transition metal oxides.",1212.5912v1
+2013-02-07,Ferromagnetic Exchange Anisotropy from Antiferromagnetic Superexchange in the Mixed 3d-5d Transition-Metal Compound Sr3CuIrO6,"We report a combined experimental and theoretical study of the unusual
+ferromagnetism in the one-dimensional copper-iridium oxide Sr$_3$CuIrO$_6$.
+Utilizing Ir $L_3$ edge resonant inelastic x-ray scattering, we reveal a large
+gap magnetic excitation spectrum. We find that it is caused by an unusual
+exchange anisotropy generating mechanism, namely, strong ferromagnetic
+anisotropy arising from antiferromagnetic superexchange, driven by the
+alternating strong and weak spin-orbit coupling on the $5d$ Ir and 3d Cu
+magnetic ions, respectively. From symmetry consideration, this novel mechanism
+is generally present in systems with edge-sharing Cu$^{2+}$O$_4$ plaquettes and
+Ir$^{4+}$O$_6$ octahedra. Our results point to unusual magnetic behavior to be
+expected in mixed 3d-5d transition-metal compounds via exchange pathways that
+are absent in pure 3d or 5d compounds.",1302.1818v2
+2013-02-23,Crystal structures of spin-Jahn-Teller ordered MgCr_2O_4 and ZnCr_2O_4,"Magnetic ordering in the geometrically frustrated magnetic oxide spinels
+MgCr_2O_4 and ZnCr_2O_4 is accompanied by a structural change that helps
+relieve the frustration. Analysis of high-resolution synchrotron X-ray
+scattering reveals that the low-temperature structures are well described by a
+two-phase model of tetragonal I4_1/amd and orthorhombic Fddd symmetries. The
+Cr_4 tetrahedra of the pyrochlore lattice are distorted at these
+low-temperatures, with the Fddd phase displaying larger distortions than the
+I4_1/amd phase. The spin-Jahn-Teller distortion is approximately one order of
+magnitude smaller than is observed in first-order Jahn-Teller spinels such as
+NiCr_2O_4 and CuCr_2O_4. In analogy with NiCr_2O_4 and CuCr_2O_4, we further
+suggest that the precise nature of magnetic ordering can itself provide a
+second driving force for structural change.",1302.5746v2
+2013-03-13,"Ferromagnetic exchange, spin-orbit coupling and spiral magnetism at the LaAlO_3/SrTiO_3 interface","The electronic properties of the polar interface between insulating oxides is
+a subject of great current interest. An exciting new development is the
+observation of robust magnetism at the interface of two non-magnetic materials
+LaAlO_3 (LAO) and SrTiO_3 (STO). Here we present a microscopic theory for the
+formation and interaction of local moments, which depends on essential features
+of the LAO/STO interface. We show that correlation-induced moments arise due to
+interfacial splitting of orbital degeneracy. We find that gate-tunable Rashba
+spin-orbit coupling at the interface influences the exchange interaction
+mediated by conduction electrons. We predict that the zero-field ground state
+is a long-wavelength spiral and show that its evolution in an external field
+accounts semi-quantitatively for torque magnetometry data. Our theory describes
+qualitative aspects of the scanning SQUID measurements and makes several
+testable predictions for future experiments.",1303.3275v2
+2013-03-22,Ultralow-current-density and bias-field-free spin-transfer nano-oscillator,"The spin-transfer nano-oscillator (STNO) offers the possibility of using the
+transfer of spin angular momentum via spin-polarized currents to generate
+microwave signals. However, at present STNO microwave emission mainly relies on
+both large drive currents and external magnetic fields. These issues hinder the
+implementation of STNOs for practical applications in terms of power
+dissipation and size. Here, we report microwave measurements on STNOs built
+with MgO-based magnetic tunnel junctions having a planar polarizer and a
+perpendicular free layer, where microwave emission with large output power,
+excited at ultralow current densities, and in the absence of any bias magnetic
+fields is observed. The measured critical current density is over one order of
+magnitude smaller than previously reported. These results suggest the
+possibility of improved integration of STNOs with complementary
+metal-oxide-semiconductor technology, and could represent a new route for the
+development of the next-generation of on-chip oscillators.",1303.5562v1
+2013-03-24,Self-energy effects in electronic Raman spectra of doped cuprates due to magnetic fluctuations,"We present results for magnetic excitations in doped copper oxides using the
+random phase approximation and itinerant electrons. In the [1,0] direction the
+observed excitations resemble dispersive quasi-particles both in the normal and
+superconducting state similar as in recent resonant inelastic X-ray scattering
+(RIXS) experiments. In the [1,1] direction the excitations form, except for the
+critical region near the antiferromagnetic wave vector ${\bf Q}=(\pi,\pi)$,
+only very broad continua. Using the obtained spin propagators we calculate
+electron self-energies and their effects on electronic Raman spectra. We show
+that the recently observed additional peak at about twice the pair breaking in
+B$_{1g}$ symmetry below T$_c$ in HgBa$_2$CuO$_{4+\delta}$ can be explained as a
+self-energy effect where a broken Cooper pair and a magnetic excitation appear
+as final states. The absence of this peak in B$_{2g}$ symmetry, which probes
+mainly electrons near the nodal direction, is explained by their small
+self-energies compared to those in the antinodal direction.",1303.5975v1
+2013-04-06,Theoretical study on copper's energetics and magnetism in TiO2 polymorphs,"We carried out density functional theory calculations to model the electronic
+structure and the magnetic interactions in copper doped anatase and rutile
+titanium dioxide in order to shed light on the potential of these systems as
+magnetic oxides using different density functional schemes. In both polymorphs
+copper dopant was found to be most stable in substitutional lattice positions.
+Ferromagnetism is predicted to be stable well above room temperature with long
+range interactions prevailing in the anatase phase while the rutile phase
+exhibits only short range superexchange interaction among nearest neighbouring
+Cu ions. Additionally, energetic evaluation of dopants in scattered and compact
+configurations reveals a dopant clustering tendency in anatase TiO2.",1304.1854v2
+2013-07-20,Emergent Spin-Filter at the interface between Ferromagnetic and Insulating Layered Oxides,"We report a strong effect of interface-induced magnetization on the transport
+properties of magnetic tunnel junctions consisting of ferromagnetic manganite
+La$_{0.7}$Ca$_{0.3}$MnO$_{3}$ and insulating cuprate PrBa$_{2}$Cu$_{3}$O$_{7}$.
+Contrary to the typically observed steady increase of the tunnel
+magnetoresistance with decreasing temperature, this system exhibits a sudden
+anomalous decrease at low temperatures. Interestingly, this anomalous behavior
+can be attributed to the competition between the positive spin polarization of
+the manganite contacts and the negative spin-filter effect from the
+interface-induced Cu magnetization.",1307.5475v2
+2013-10-05,"Effect of ""dipolar-biasing"" on the tunability of tunneling magnetoresistance in transition metal oxide systems","We observe an unusual tunneling magnetoresistance (TMR) phenomenon in a
+composite of La$_{2/3}$Sr$_{1/3}$MnO$_{3}$ with CoFe$_{2}$O$_{4}$ where the TMR
+versus applied magnetic field loop suggests a ""negative coercive field"".
+Tracing its origin back to a ""dipolar-biasing"" of La$_{2/3}$Sr$_{1/3}$MnO$_{3}$
+by CoFe$_{2}$O$_{4}$, we show that the TMR of even a single composite can be
+tuned continuously so that the resistance peak or the highest sensitivity of
+the TMR can be positioned anywhere on the magnetic field axis with a suitable
+magnetic history of the sample. This phenomenon of an unprecedented tunability
+of the TMR should be present in general in all such composites.",1310.1466v1
+2013-10-22,Conduction of spin currents through insulating oxides,"Spintronics is a field of electronics based on using the electron spin
+instead of its charge. The recent advance in the manipulation of pure spin
+currents, i.e. angular momentum transfer not associated to conventional charge
+currents, has opened new opportunities to build spin based devices with low
+energy consumption. It has also allowed to integrate ferromagnetic insulators
+in spintronic devices, either as spin sources or spin conductors using their
+magnetic excitations to propagate a spin signal. Antiferromagnetic insulators
+belong to another class of materials that can also sustain magnetic
+excitations, even with a higher group velocity. Hence, they have potential as
+angular momentum conductors, possibly making faster spin devices. At the
+opposite end, angular momentum insulators are also required in spintronic
+circuits. The present letter underlines some essential features relevant for
+spin current conduction, based on measurements of angular momentum transmission
+in antiferromagnetic NiO and in the non-magnetic light element insulator
+SiO$_2$.",1310.6000v1
+2013-11-03,Probing the Electromagnetic Local Density of States with a Strongly Mixed Electric and Magnetic Dipole Emitter,"We identify a solid-state quantum emitter whose room-temperature radiative
+decay is mediated by a nearly equal mixture of isotropic electric dipole (ED)
+and magnetic dipole (MD) transitions. Using energy-momentum spectroscopy, we
+experimentally show that the near-infrared $^3$T$_2{\rightarrow}^3$A$_2$
+emission from divalent-nickel-doped magnesium oxide (Ni$^{2+}$:MgO) is composed
+of $\sim$50% MD and $\sim$50% ED transitions. We then demonstrate that the
+spontaneous emission rate of these ions near planar interfaces is determined by
+the combined electric and magnetic local density of optical states (LDOS). This
+electromagnetic LDOS probes the total mode density, and thus similar to thermal
+emission, these unique electronic emitters effectively excite all polarizations
+and orientations of the electromagnetic field.",1311.0516v1
+2013-11-19,Hour-glass magnetic spectrum in a stripe-less insulating transition metal oxide,"An hour-glass shaped magnetic excitation spectrum appears to be an universal
+characteristic of the high-temperature superconducting cuprates. Fluctuating
+charge stripes or alternative band structure approaches are able to explain the
+origin of these spectra. Recently, an hour- glass spectrum has been observed in
+an insulating cobaltate, thus, favouring the charge stripe scenario. Here we
+show that neither charge stripes nor band structure effects are responsible for
+the hour-glass dispersion in a cobaltate within the checkerboard charge ordered
+regime of La2-xSrxCoO4. The search for charge stripe ordering reflections
+yields no evidence for charge stripes in La1.6Sr0.4CoO4 which is supported by
+our phonon studies. With the observation of an hour-glass-shaped excitation
+spectrum in this stripe-less insulating cobaltate, we provide experimental
+evidence that the hour-glass spectrum is neither necessarily connected to
+charge stripes nor to band structure effects, but instead, probably intimately
+coupled to frustration and arising chiral or non-collinear magnetic
+correlations.",1311.4757v2
+2014-01-03,Intrinsic paramagnetism and aggregation of manganese dopants in SrTiO$_3$,"Using local-probe magnetic-characterization techniques of muon spin
+relaxation ($\mu$SR) and electron spin resonance (ESR) we have investigated the
+Mn-induced magnetism of the wide-bandgap perovskite SrTiO$_3$. Our results
+clearly demonstrate that this diluted magnetic oxide (DMO) remains paramagnetic
+down to low temperatures for both doping cases, i.e., when Mn substitutes for
+Sr or Ti. In addition, both experimental techniques have unveiled that the
+distribution of individual Mn$^{2+}$ and Mn$^{4+}$ ions is nonrandom, as these
+ions partially aggregate into nanosized clusters.",1401.0607v2
+2014-10-29,Large time-dependent coercivity and resistivity modification under sustained voltage application in a Pt/Co/AlOx/Pt junction,"The coercivity and resistivity of a Pt/Co/AlOx/Pt junction are measured under
+sustained voltage application. High bias voltages of either polarity are
+determined to cause a strongly enhanced, reversible coercivity modification
+compared to low voltages. Time-resolved measurements show a logarithmic
+development of the coercive field in this regime, which continues over a period
+as long as thirty minutes. Furthermore, the resistance of the dielectric
+barrier is found to change strongly and reversibly on the same time scale,
+suggesting an electrochemical process is taking place within the dielectric. It
+is argued that the migration of oxygen vacancies at the magnet/oxide interface
+could explain both the resistance variation and the enhanced electric field
+effect at high voltages. A thermal fluctuation aftereffect model is applied to
+account for the observed logarithmic dependence.",1410.8018v1
+2014-10-31,Enhanced ferrimagnetism in auxetic NiFe2O4 in the crossover to the ultrathin film limit,"We investigate the sensitive interplay between magnetic, electronic and
+structural properties in the ferrimagnetic oxide NiFe2O4. Emphasis is placed on
+the impact of reduced dimensionality in the crossover from bulk-like to
+ultrathin films. We observed an enhanced saturation magnetization $M_S$ for
+ultrathin NiFe2O4 films on Nb-SrTiO3 (001) substrates that co-occurs with a
+reduced out-of-plane lattice constant under compressive in-plane epitaxial
+strain. We found a bulk-like cationic coordination of the inverse spinel
+lattice independent of the NiFe2O4 film thickness -- thus ruling out a cationic
+inversion that nominally could account for an enhanced $M_S$. Our study instead
+uncovers a reduction of the unit cell volume, i.e. an auxetic behavior in
+ultrathin NiFe2O4 films, which may result in an enhanced magnetic exchange
+caused by an increased interatomic electronic localization.",1410.8782v1
+2014-11-11,Mechanism of spin crossover in LaCoO3 resolved by shape magnetostriction in pulsed magnetic fields,"In the scientific description of unconventional transport properties of
+oxides (spin-dependent transport, superconductivity etc.), the spin-state
+degree of freedom plays a fundamental role. Because of this, temperature- or
+magnetic field-induced spin-state transitions are in the focus of solid-state
+physics. Cobaltites, e.g. LaCoO3, are prominent examples showing these spin
+transitions. However, the microscopic nature of the spontaneous spin crossover
+in LaCoO3 is still controversial. Here we report magnetostriction measurements
+on LaCoO3 in magnetic fields up to 70 T to study the sharp, field-induced
+transition at Hc ~ 60 T. Measurements of both longitudinal and transversal
+magnetostriction allow us to separate magnetovolume and magnetodistortive
+changes. We find a large increase in volume, but only a very small increase in
+tetragonal distortion at Hc. The results, supported by electronic energy
+calculations by the configuration interaction cluster method, provide
+compelling evidence that above Hc LaCoO3 adopts a correlated low spin/high spin
+state.",1411.2757v1
+2014-11-12,Observation of transient superconductivity at the LaAlO$_3$/SrTiO$_3$ interface,"We report the observation of a magnetic field assisted transient
+superconducting state in the two dimensional electron gas existing at the
+interface of LaAlO$_3$/SrTiO$_3$ heterostructures. This metastable state
+depends critically on the density of charge carriers in the system. It appears
+concomitantly with a Lifshitz transition as a consequence of the interplay
+between ferromagnetism and superconductivity and the finite relaxation time of
+the in-plane magnetization. Our results clearly demonstrate the inherently
+metastable nature of the superconducting state competing with a magnetic order
+in these systems. The co-existence of superconductivity and ferromagnetism in
+the conducting electronic layer formed at the interface of insulating oxides
+has thrown up several intriguing and as yet unanswered questions. An open
+question in this field is the energetics of the interplay between these two
+competing orders and the present observation goes a long way in understanding
+the underlying mechanism.",1411.3103v2
+2015-04-11,Magnetic Nanorods Confined in a Lamellar Lyotropic Phase,"The dilute lamellar phase of the nonionic surfactant C$_{12}$EO$_5$ was doped
+with goethite (iron oxide) nanorods up to a fraction of 5 vol. %. The
+interaction between the inclusions and the host phase was studied by polarized
+optical microscopy (with or without an applied magnetic field) and by
+small-angle X-ray scattering. We find that, when the orientation of the
+nanorods is modified using the magnetic field, the texture of the lamellar
+phase changes accordingly; one can thus induce a homeotropic-planar
+reorientation transition. On the other hand, the lamellar phase induces an
+attractive interaction between the nanorods. In more concentrated lamellar
+phases (under stronger confinement) the particles form aggregates. This
+behavior is not encountered for a similar system doped with spherical
+particles, emphasizing the role of particle shape in the interaction between
+doping particles and the host phase.",1504.02879v1
+2015-06-25,Multi-band theory of superconductivity at the LaAlO$_3$/SrTiO$_3$ interface,"We present a multi-band model for superconductivity at the metallic interface
+between insulating oxides LaAlO$_3$ and SrTiO$_3$ (001). Using a
+self-consistent Bogoliubov-de Gennes theory, formulated with the realistic
+bands at the interface, we investigate the spin-singlet and spin-triplet
+pairings in intra-band and inter-band channels. We find that the Rashba and
+atomic spin-orbit interactions at the interface induce singlet pairing in the
+inter-band channel and triplet pairing in both the intra-band and inter-band
+channels when the pairing amplitude in the singlet intra-band channel is
+finite. The gate-voltage variation of superconductivity is resolved in
+different pairing channels, compared with experimental results and found to
+match quite well. Interestingly, an enhancement of the superconducting
+transition temperature by external in-plane magnetic field is found revealing
+the existence of a hidden superconducting state above the observed one. As the
+interface is known to possess high level of inhomogeneity, we explore the role
+of non-magnetic disorder incorporating thermal phase fluctuations by using a
+Monte-Carlo method. We show that even after the transition to the
+non-superconducting phase, driven by temperature or magnetic field, the
+interface possesses localized Cooper pairs whose signature was observed in
+previous experiments.",1506.07841v1
+2015-08-06,Odd-parity magnetoresistance in pyrochlore iridate thin films with broken time-reversal symmetry,"A new class of materials termed topological insulators have been intensively
+investigated due to their unique Dirac surface state carrying dissipationless
+edge spin currents. Recently, it has been theoretically proposed that the three
+dimensional analogue of this type of band structure, the Weyl Semimetal phase,
+is materialized in pyrochlore oxides with strong spin-orbit coupling,
+accompanied by all-in-all-out spin ordering. Here, we report on the fabrication
+and magnetotransport of Eu2Ir2O7 single crystalline thin films. We reveal that
+one of the two degenerate all-in-all-out domain structures, which are connected
+by time-reversal operation, can be selectively formed by the polarity of the
+cooling magnetic field. Once formed, the domain is robust against an oppositely
+polarised magnetic field, as evidenced by an unusual odd field dependent term
+in the magnetoresistance and an anomalous term in the Hall resistance. Our
+findings pave the way for exploring the predicted novel quantum transport
+phenomenon at the surfaces/interfaces or magnetic domain walls of pyrochlore
+iridates.",1508.01318v1
+2015-09-10,Ultrafast cooling and heating scenarios for the laser induced phase transition in CuO,"The multiferroic compound CuO exhibits low temperature magnetic properties
+similar to antiferromagnetic iron oxides, while the electronic properties have
+much more in common with the high $T_c$ cuprate superconductors. This suggests
+novel possibilities for the ultrafast optical excitation of magnetism. On the
+basis on atomistic spin dynamics simulations, we study the effect of
+phonon-assisted multimagnon absorption and photodoping on the spin dynamics in
+the vicinity of the first-order phase transition from collinear to spin-spiral
+magnetic order. Similar as in recent experiments, we find that for both
+excitations the phase transition can proceed on the picosecond timescale.
+Interestingly, however, these excitation mechanisms display very distinct
+dynamics. Following photodoping, the spin system first cools down on sub-ps
+timescales, which we explain as an ultrafast magnetocaloric effect. Opposed to
+this, following phonon-assisted multimagnon excitation the spin systems rapidly
+heats up and subsequently evolves to the noncollinear phase even under the
+influence of isotropic exchange interactions alone.",1509.03202v2
+2015-11-01,Reciprocal spin Hall effects in conductors with strong spin-orbit coupling: a review,"Spin Hall effect and its inverse provide essential means to convert charge to
+spin currents and vice versa, which serve as a primary function for spintronic
+phenomena such as the spin-torque ferromagnetic resonance and the spin Seebeck
+effect. These effects can oscillate magnetization or detect a thermally
+generated spin splitting in the chemical potential. Importantly this conversion
+process occurs via the spin-orbit interaction, and requires neither magnetic
+materials nor external magnetic fields. However, the spin Hall angle, i.e., the
+conversion yield between the charge and spin currents, depends severely on the
+experimental methods. Here we discuss the spin Hall angle and the spin
+diffusion length for a variety of materials including pure metals such as Pt
+and Ta, alloys and oxides determined by the spin absorption method in a lateral
+spin valve structure.",1511.00332v1
+2015-11-05,Interface control of electronic transport across the magnetic phase transition in SrRuO_3/SrTiO_3 heterointerface,"The emerging material class of complex-oxides, where manipulation of physical
+properties lead to new functionalities at their heterointerfaces, is expected
+to open new frontiers in Spintronics. For example, SrRuO_3 is a promising
+material where external stimuli like strain, temperature and structural
+distortions control the stability of electronic and magnetic states, across its
+magnetic phase transition, useful for Spintronics. Despite this, not much has
+been studied to understand such correlations in SrRuO_3. Here we explore the
+influence of electron-lattice correlation to electron-transport, at interfaces
+between SrRuO_3 and Nb:SrTiO_3 across its ferromagnetic transition, using a
+nanoscale transport probe and first-principles calculations. We find that the
+geometrical reconstructions at the interface and hence modifications in
+electronic structures dominate the transmission across its ferromagnetic
+transition, eventually flipping the charge-transport length-scale in SrRuO_3.
+This approach can be easily extended to other devices where competing ground
+states can lead to different functional properties across their
+heterointerfaces.",1511.01933v1
+2016-01-22,Micrometer-scale ballistic transport of electron pairs in LaAlO3/SrTiO3 nanowires,"High-mobility complex-oxide heterostructures and nanostructures offer new
+opportunities for extending the paradigm of quantum transport beyond the realm
+of traditional III-V or carbon-based materials. Recent quantum transport
+investigations with LaAlO$_3$/SrTiO$_3$-based quantum dots have revealed the
+existence of a strongly correlated phase in which electrons form spin-singlet
+pairs without becoming superconducting. Here we report evidence for
+micrometer-scale ballistic transport of electron pairs in quasi-one-dimensional
+(quasi-1D) LaAlO$_3$/SrTiO$_3$ nanowire cavities. In the paired phase,
+Fabry-Perot-like quantum interference is observed, in sync with conductance
+oscillations observed in the superconducting regime (at zero magnetic field).
+Above a critical magnetic field $B_p$, electron pairs unbind and conductance
+oscillations shift with magnetic field. These experimental observations extend
+the regime of ballistic electronic transport to strongly correlated phases.",1601.06053v1
+2016-02-01,All-in-all-out magnetic domain wall conduction in pyrochlore iridate heterointerface,"Pyrochlore oxides possessing ""all-in-all-out"" spin ordering have attracted
+burgeoning interest as a rich ground of emergent states. This ordering has two
+distinct types of magnetic domains (all-in-all-out or all-out-all-in) with
+broken time-reversal symmetry, and a non-trivial metallic surface state has
+been theoretically demonstrated to appear at their domain wall. Here, we report
+on observation of this metallic conduction at the single
+all-in-all-out/all-out-all-in magnetic domain wall formed at the
+heterointerface of two pyrochlore iridates. By utilizing different
+magnetoresponses of them with different lanthanide ions, the domain wall is
+controllably inserted at the heterointerface, the surface state being detected
+as anomalous conduction enhancement with a ferroic hysteresis. Our
+establishment paves the way for further investigation and manipulation of this
+new type of surface transport.",1602.00450v1
+2016-02-20,Effect of disorder on the dimer transition of the honeycomb-lattice compound Li$_{2}$RuO$_3$,"We report the dependence of magnetic properties on the crystalline disorder
+in Li$_{2}$RuO$_3$ with Ru honeycomb lattice. This oxide exhibits
+unconventional Ru-dimer transition below $T_\text{d} \sim$ 540 K. We
+demonstrate that the cell parameters, related to the coherence of the dimer
+formation, are strongly dependent on the synthesis procedure. We show that the
+magnetic behavior at the dimer transition is closely related to the lattice
+parameters. In particular, we revealed that samples with well-ordered dimers
+exhibit a first-order magnetic transition with the onset exceeding 550~K,
+higher than that reported previously. We discuss possible dimer configurations
+leading to this magneto-lattice coupling.",1602.06396v1
+2016-02-27,Quantum topological Hall effect and noncoplanar antiferromagnetism in K$_{0.5}$RhO$_2$,"Quantum anomalous Hall (QAH) phase is a two-dimensional bulk ferromagnetic
+insulator with a nonzero Chern number in presence of spin-orbit coupling (SOC)
+but absence of applied magnetic fields. Associated metallic chiral edge states
+host dissipationless current transport in electronic devices. This intriguing
+QAH phase has recently been observed in magnetic impurity-doped topological
+insulators, {\it albeit}, at extremely low temperatures. Based on
+first-principles density functional calculations, here we predict that layered
+rhodium oxide K$_{0.5}$RhO$_2$ in noncoplanar chiral antiferromagnetic state is
+an unconventional three-dimensional QAH insulator with a large band gap and a
+Neel temperature of a few tens Kelvins. Furthermore, this unconventional QAH
+phase is revealed to be the exotic quantum topological Hall effect caused by
+nonzero scalar spin chirality due to the topological spin structure in the
+system and without the need of net magnetization and SOC.",1602.08553v1
+2016-02-27,Coupled magnetic and elastic properties in LaPr(CaSr)MnO manganites,"We investigate a series of manganese oxides, the
+La0.225Pr0.4(Ca1-xSrx)0.375MnO3 system. The x = 0 sample is a prototype
+compound for the study of phase separation in manganites, where ferromagnetic
+and charge ordered antiferromagnetic phases coexist. Replacing Ca2+ by Sr2+
+gradually turns the system into a homogeneous ferromagnet. Our results show
+that the material structure plays a major role in the observed magnetic
+properties. On cooling, at temperatures below 100 K, a strong contraction of
+the lattice is followed by an increase in the magnetization. This is observed
+both through thermal expansion and magnetostriction measurements, providing
+distinct evidence of magneto-elastic coupling in these phase separated
+compounds.",1602.08597v3
+2016-03-21,Ferrimagnetic ordering and spin entropy of field-dependent intermediate spins in Na0.82CoO2,"The peculiar field-dependent magnetism of Na0.82CoO2 has been investigated
+through an analysis of its DC and AC spin susceptibilities. To account for the
+easily activated narrow b2g-a1g gap of the crystal field for Co in the cobalt
+oxide layer, the spin-state transition of Co3+ (3d6) between the low spin (LS)
+state b2g^2-a1g^0 of S=0 and the intermediate spin (IS) state b2g^1-a1g^1 of
+S=1 is thus seen as thermally activated and exhibits a Boltzmann distribution.
+The IS state of Co3+ within each sqrt(13a) hexagonal superlattice formed by the
+S=1/2 state of the Co4+ ions appears randomly within each supercell and shows
+significant temperature and field dependence. The magnetic field is found to
+assist in pinning down the thermally activated state of Co3+ and swings the
+Boltzmann distribution weight toward a higher fraction of the IS state. The
+field dependence of the in-plane magnetic moment from the added number of S=1
+spins is used to explain the origin of A-type antiferromagnetic (AF) ordering,
+particularly that the ferromagnetic (FM)-like behavior below TN at low field is
+actually a ferrimagnetic IS spin ordering of Co3+.",1603.06451v1
+2016-04-12,High field magneto-transport in two-dimensional electron gas LaAlO3/SrTiO3,"Transport properties of the complex oxide LaAlO3/SrTiO3 interface are
+investigated under high magnetic field (55T). By rotating the sample with
+respect to the magnetic field, the two-dimensional nature of charge transport
+is clearly established. Small oscillations of the agnetoresistance with altered
+periodicity are observed when plotted versus inverse magnetic field. We
+attribute this effect to Rashba spin-orbit coupling which remains consistent
+with large negative magnetoresistance when the field is parallel to the sample
+plane. A large inconsistency between the carrier density extracted from
+Shubnikov-de Haas analysis and from the Hall effect is explained by the
+contribution to transport of at least two bands with different mobility.",1604.03451v1
+2017-02-17,An ultra-sensitive and wideband magnetometer based on a superconducting quantum interference device,"The magnetic field noise in superconducting quantum interference devices
+(SQUIDs) used for biomagnetic research such as magnetoencephalography or
+ultra-low-field nuclear magnetic resonance is usually limited by instrumental
+dewar noise. We constructed a wideband, ultra-low noise system with a 45 mm
+diameter superconducting pick-up coil inductively coupled to a current sensor
+SQUID. Thermal noise in the liquid helium dewar is minimized by using
+aluminized polyester fabric as superinsulation and aluminum oxide strips as
+heat shields, respectively. With a magnetometer pick-up coil in the center of
+the Berlin magneti- cally shielded room 2 (BMSR2) a noise level of around 150
+aT Hz$^{-1/2}$ is achieved in the white noise regime between about 20 kHz and
+the system bandwidth of about 2.5 MHz. At lower frequencies, the resolution is
+limited by magnetic field noise arising from the walls of the shielded room.
+Modeling the BMSR2 as a closed cube with continuous \mu-metal walls we can
+quantitatively reproduce its measured field noise.",1702.05428v1
+2017-08-29,"Structural, magnetic, and electronic properties of GdTiO3 Mott insulator thin films grown by pulsed laser deposition","We report on the optimization process to synthesize epitaxial thin films of
+GdTiO3 on SrLaGaO4 substrates by pulsed laser deposition. Optimized films are
+free of impurity phases and are fully strained. They possess a magnetic Curie
+temperature TC = 31.8 K with a saturation magnetization of 4.2 muB per formula
+unit at 10 K. Transport measurements reveal an insulating response, as
+expected. Optical spectroscopy indicates a band gap of 0.7 eV, comparable to
+the bulk value. Our work adds ferrimagnetic orthotitanates to the palette of
+perovskite materials for the design of emergent strongly correlated states at
+oxide interfaces using a versatile growth technique such as pulsed laser
+deposition.",1708.08785v1
+2018-04-17,Emergent Magnetism at the 3$d$-5$d$ Interface: SrMnO$_3/$SrIrO$_3$,"Recent experiments have found new magnetic behaviors, which are different
+from the parent bulk materials, at the interfaces between 3$d$ and 5$d$ oxides
+such as SrMnO$_3$ (SMO) and SrIrO$_3$ (SIO). The system is of considerable
+interest due to the strong spin-orbit coupling in the 5$d$ materials on one
+hand and the double exchange physics in SMO on the other, which belongs to the
+class of the colossal magnetoresistive (CMR) manganites. In order to gain
+insight into the physics of the system, we have performed density-functional
+studies on a selected interface structure, viz., the (SMO)$_1$(SIO)$_1$
+superlattice, which has been experimentally grown and studied. Our
+density-functional results show that the interfacial magnetism is controlled by
+a net charge transfer at the interface from the SIO to the SMO side, turning
+both of them into ferromagnetic metal from the original antiferromagnetic
+insulating state in the bulk. The transferred electrons to the SMO side make it
+ferromagnetic through the Anderson-Hasegawa double exchange interaction, while
+the SIO part becomes ferromagnetic due to the doping of the half-filled
+Mott-Hubbard insulator as suggested by the Nagaoka Theorem. Our results are
+discussed in the context of the experiments for the same structure.",1804.06381v1
+2018-11-06,Skew scattering dominated anomalous Nernst effect in monovalent cation doped bulk La1-xNaxMnO3,"We report the anomalous Nernst effect (ANE), i.e. creation of electrical
+voltage transverse to the direction of applied temperature gradient and
+magnetic field in bulk samples of La1-xNaxMnO3 (x = 0.02, 0.05, 0.1 and 0.3)
+whose ferromagnetic Cure temperature(TC) varies from 251 K for x = 0.02 to 310
+K for x = 0.3. We measured both the magnetic field and temperature dependences
+of ANE. While ANE is negligible much above TC, it increases rapidly at TC and
+exhibits a peak just below it. The field dependence of ANE closely follows
+magnetization. The maximum value of ANE at TC increases from x = 0.02 to 0.1,
+but decreases significantly for x = 0.3. Besides ANE, we also measured dc
+resistivity and longitudinal Seebeck coefficient as a function of temperature
+and used these data to analyze our results. Our data analysis indicates that
+skew scattering is the main source of the ANE in these oxides.",1811.02432v1
+2018-11-14,Intercalated Rare-Earth Metals under Graphene on SiC,"Intercalation of rare earth metals ($RE$ = Eu, Dy, and Gd) is achieved by
+depositing the $RE$ metal on graphene that is grown on silicon-carbide (SiC)
+and by subsequent annealing at high temperatures to promote intercalation. STM
+images of the films reveal that the graphene layer is defect free and that each
+of the intercalated metals has a distinct nucleation pattern. Intercalated Eu
+forms nano-clusters that are situated on the vertices of a Moir{\`e} pattern,
+while Dy and Gd form randomly distributed nano-clusters. X-ray magnetic
+circular dichroism (XMCD) measurements of intercalated films reveal the
+magnetic properties of these $RE$'s nano-clusters. Furthermore, field
+dependence and temperature dependence of the magnetic moments extracted from
+the XMCD show paramagnetic-like behaviors with moments that are generally
+smaller than those predicted by the Brillouin function. XMCD measurements of
+$RE$-oxides compared with those of the intercalated $RE$'s under graphene after
+exposure to air for months indicate that the graphene membranes protect these
+intercalants against oxidation.",1811.06111v1
+2014-03-03,High-energy spin and charge excitations in electron-doped copper oxide superconductors,"The evolution of electronic (spin and charge) excitations upon carrier doping
+is an extremely important issue in superconducting layered cuprates and the
+knowledge of its asymmetry between electron- and hole-dopings is still
+fragmentary. Here we combine x-ray and neutron inelastic scattering
+measurements to track the doping dependence of both spin and charge excitations
+in electron-doped materials. Copper L3 resonant inelastic x-ray scattering
+spectra show that magnetic excitations shift to higher energy upon doping.
+Their dispersion becomes steeper near the magnetic zone center and deeply mix
+with charge excitations, indicating that electrons acquire a highly itinerant
+character in the doped metallic state. Moreover, above the magnetic
+excitations, an additional dispersing feature is observed near the
+{\Gamma}-point, and we ascribe it to particle-hole charge excitations. These
+properties are in stark contrast with the more localized spin-excitations
+(paramagnons) recently observed in hole-doped compounds even at high
+doping-levels.",1403.0283v1
+2016-11-04,The skyrmion switch: turning magnetic skyrmion bubbles on and off with an electric field,"Nanoscale magnetic skyrmions are considered as potential information carriers
+for future spintronics memory and logic devices. Such applications will require
+the control of their local creation and annihilation, which involves so far
+solutions that are either energy consuming or difficult to integrate. Here we
+demonstrate the control of skyrmion bubbles nucleation and annihilation using
+electric field gating, an easily integrable and potentially energetically
+efficient solution. We present a detailed stability diagram of the skyrmion
+bubbles in a Pt/Co/oxide trilayer and show that their stability can be
+controlled via an applied electric field. An analytical bubble model, with the
+Dzyaloshinskii-Moriya interaction imbedded in the domain wall energy, account
+for the observed electrical skyrmion switching effect. This allows us to unveil
+the origin of the electrical control of skyrmions stability and to show that
+both magnetic dipolar interaction and the Dzyaloshinskii-Moriya interaction
+play an important role in the skyrmion bubble stabilization.",1611.01453v4
+2016-11-29,Cluster superconductivity in the magnetoelectric Pb(Fe1/2Sb1/2)O3 ceramics,"We report the observation of cluster (local) superconductivity in the
+magnetoelectric Pb(Fe1/2Sb1/2)O3 ceramics prepared at a hydrostatic pressure of
+6 GPa and temperatures 1200-1800 K to stabilize the perovskite phase. The
+superconductivity is manifested by an abrupt drop of the magnetic
+susceptibility at the critical temperature TC 7 K. Both the magnitude of this
+drop and TC decrease with magnetic field increase. Similarly, the low-field
+paramagnetic absorption measured by EPR spectrometer drops significantly below
+TC as well. The observed effects and their critical magnetic field dependence
+are interpreted as manifestation of the superconductivity and Meissner effect
+in metallic Pb nanoclusters existing in the ceramics. Their volume fraction and
+average size were estimated as 0.1-0.2% and 140-150 nm, respectively. The
+superconductivity related effects disappear after oxidizing annealing of the
+ceramics.",1611.09895v1
+2017-01-31,SANS contrast variation study of magnetoferritin structure at various iron loading,"Magnetoferritin, a synthetic derivate of iron storage protein - ferritin, has
+been synthesized with different iron oxide loading values. Small-angle neutron
+scattering experiments were applied to study the structure of magnetoferritin
+solutions using contrast variation method by varying the light to heavy water
+ratio of the solvent. Higher iron loading leads to increasing of the neutron
+scattering length density of magnetoferritin and also to the increase of the
+polydispersity of complexes. The formation of the magnetic core and the
+variation of the protein shell structure upon iron loading are concluded.",1701.09174v1
+2008-07-24,Chemical functionalization of graphene with defects,"Defects change essentially not only electronic but also chemical properties
+of graphene being centers of its chemical activity. Their functionalization is
+a way to modify electronic and crystal structure of graphene which may be
+important for graphene-based nanoelectronics. Using hydrogen as an example, we
+have simulated a chemistry of imperfect graphene for a broad class of defects
+(Stone-Wales defects, bivacancy, nitrogen substitution impurity, and zigzag
+edges) by density functional calculations. We have studied also an effect of
+finite width of graphene nanoribbons on their chemical properties. It is shown
+that magnetism at graphene edges is fragile with respect to oxidation and,
+therefore, a chemical protection of the graphene edges may be required for
+application of graphene in spintronics. At the same time, hydrogenation of the
+Stone-Wales defects may be a perspective way to create magnetic carbon.",0807.3855v2
+2011-11-15,Origin of ferroelectricity in high-$T_c$ magnetic ferroelectric CuO,"Cupric oxide is a unique magnetic ferroelectric material with a transition
+temperature significantly higher than the boiling point of liquid nitrogen.
+However, the mechanism of high-T$_c$ multiferroicity in CuO remains puzzling.
+In this paper, we clarify the mechanism of high-T$_c$ multiferroicity in CuO,
+using combined first-principles calculations and an effective Hamiltonian
+model. We find that CuO contains two magnetic sublattices, with strong
+intrasublattice interactions and weakly frustrated intersublattice
+interactions, which may represent one of the main reasons for the high ordering
+temperature of the compound. The weak spin frustration leads to incommensurate
+spin excitations that dramatically enhance the entropy of the mutliferroic
+phase and eventually stabilize that phase in CuO.",1111.3414v2
+2014-06-20,Evidence for spin-triplet superconducting correlations in metal-oxide heterostructures with non-collinear magnetization,"Heterostructures composed of ferromagnetic La0.7Sr0.3MnO3, ferromagnetic
+SrRuO3, and superconducting YBa2Cu3Ox were studied experimentally. Structures
+of composition Au/La0.7Sr0.3MnO3/SrRuO3/YBa2Cu3Ox were prepared by pulsed laser
+deposition, and their high quality was confirmed by X-ray diffraction and
+reflectometry. A non-collinear magnetic state of the heterostructures was
+revealed by means of SQUID magnetometry and polarized neutron reflectometry. We
+have further observed superconducting currents in mesa-structures fabricated by
+deposition of a second superconducting Nb layer on top of the heterostructure,
+followed by patterning with photolithography and ion-beam etching. Josephson
+effects observed in these mesa-structures can be explained by the penetration
+of a triplet component of the superconducting order parameter into the magnetic
+layers.",1406.5442v1
+2015-12-01,Nonequilibrium low temperature phase in pyrochlore iridate Y$_2$Ir$_2$O$_7$: Possibility of glass-like dynamics,"Geometrical frustration and spin-orbit coupling effect together play vital
+role to influence properties in pyrochlore based iridium oxides. Here we have
+investigated detailed structural, magnetic, thermodynamic and transport
+properties of pyrochlore iridate Y$_2$Ir$_2$O$_7$. Magnetization data show
+onset of magnetic irreversibility around temperature $T_{irr}$ $\sim$ 160 K,
+however, no sign of long-range type ferromagnetic ordering is observed below
+$T_{irr}$. Specific heat data show no visible anomaly across $T_{irr}$, and the
+analysis of data indicate sizable density of states across Fermi level.
+Temperature dependent x-ray diffraction measurements show no change in
+structural symmetry down to low temperature. The material, on the other hand,
+shows significant relaxation and aging behavior similar to glassy dynamics. The
+electronic charge transport in this highly insulating system is found to follow
+power law dependence with temperature. The material shows negative
+magnetoresistance which is explained with quantum interference effect.",1512.00233v1
+2015-12-18,Exchange Bias and Bistable Magneto-Resistance States in Amorphous TbFeCo thin Films,"Amorphous TbFeCo thin films sputter deposited at room temperature on
+thermally oxidized Si substrate are found to exhibit strong perpendicular
+magnetic anisotropy (PMA). Atom probe tomography (APT), scanning transmission
+electron microscopy (STEM), and energy dispersive spectroscopy (EDS) mapping
+have revealed two nanoscale amorphous phases with different Tb atomic
+percentages distributed within the amorphous film. Exchange bias accompanied by
+bistable magneto-resistance states has been uncovered near room temperature by
+magnetization and magneto-transport measurements. The exchange anisotropy
+originates from the exchange interaction between the ferrimagnetic and
+ferromagnetic components corresponding to the two amorphous phases. This study
+provides a platform for exchange bias and magneto-resistance switching using
+single-layer amorphous ferrimagnetic thin films that require no epitaxial
+growth.",1512.06103v1
+2017-06-07,PbTi1-xPdxO3: A New Room-temperature Magnetoelectric Multiferroic Device Material,"There have been a large number of papers on bismuth ferrite (BiFeO3) over the
+past few years, trying to exploit its room-temperature magnetoelectric
+multiferroic properties. Although these are attractive, BiFeO3 is not the ideal
+multiferroic, due to weak magnetization and the difficulty in limiting leakage
+currents. Thus there is an ongoing search for alternatives, including such
+materials as gallium ferrite (GaFeO3). In the present work we report a
+comprehensive study of the perovskite PbTi1-xPdxO3 with 0 < x < 0.3. Our study
+includes dielectric, impedance and magnetization measurements, conductivity
+analysis and study of crystallographic phases present in the samples with
+special attention paid to minor phases, identified as PdO, PbPdO2, and Pd3Pb.
+The work is remarkable in two ways: Pd is difficult to substitute into ABO3
+perovskite oxides (where it might be useful for catalysis), and Pd is magnetic
+under only unusual conditions (under strain or internal electric fields). The
+new material, as a PZT derivative, is expected to have much stronger
+piezoelectric properties than BiFeO3.",1706.02194v1
+2017-06-19,Spin Hall effect from hybridized 3$d$-4$p$ orbitals,"Electrical manipulation of magnetization by spin-orbit torque (SOT) has shown
+promise for realizing reliable magnetic memories and oscillators. To date, the
+generation of transverse spin current and SOT, whether it is of spin Hall
+effect (SHE), Rashba-Edelstein effect or spin-momentum locking origin, relies
+primarily on materials or heterostructures containing 5$d$ or 6$p$ heavy
+elements with strong spin-orbit coupling. Here we show that a paramagnetic CoGa
+compound possesses large enough spin Hall angle to allow robust SOT switching
+of perpendicularly-magnetized ferrimagnetic MnGa films in CoGa/MnGa/Oxide
+heterostructures. The spin Hall efficiency estimated via spin Hall
+magnetoresistance and harmonic Hall measurements is +0.05$\pm$0.01, which is
+surprisingly large for a system that does not contain any heavy metal element.
+First-principles calculations corroborate our experimental observations and
+suggest that the hybridized Co 3$d$ - Ga 4$p$ orbitals along R-X in the
+Brillouin zone is responsible for the intrinsic SHE. Our results suggest that
+efficient spin current generation can be realized in intermetallic by alloying
+a transition metal with a $p$-orbital element and by Fermi level tuning.",1706.05846v1
+2017-10-19,"Structural, Electrical, and Magnetic Properties of La2Ni1.5Mn0.5O6 double perovskites","Among multifunctional double perovskite oxides, La2NiMnO6 has recently drawn
+significant attention due to its importance both in terms of understanding of
+fundamental physics and potential for device applications. The relative
+alteration in Ni:Mn ratio strongly influences the structural, magnetic and
+electrical properties of La2NiMnO6. In the present study, La2Ni1.5Mn0.5O6
+sample with Ni:Mn = 3:1 ratio has been prepared using sol-gel method and
+modifications of the above physical properties from that of a stiochiometric
+sample of La2NiMnO6 are discussed. Rietveld analysis of X-ray diffraction data
+shows that La2Ni1.5Mn0.5O6 samples belong to a major monoclinic structural
+phase (P21/n), with partially disordered arrangement of Ni and Mn ions.
+Magnetic characterization and X-ray absorption near edge structure analysis
+reveal ferromagnetic ordering around 260 K between Ni2+ and Mn4+ ions while
+spin glass like behavior is revealed at ~45 K. Semiconducting nature of the
+sample was confirmed from temperature dependent resistivity measurements as
+well as from the I-V characteristics measured at room temperature.",1710.07091v2
+2018-10-15,Realizing Magnetoelectric Coupling with Hydroxide as a Knob,"Materials with a coexistence of magnetic and ferroelectric order (i.e.,
+multiferroics) provide an efficient route for the control of magnetism by
+electric fields. Unfortunately, a long-sought room temperature multiferroic
+with strongly coupled ferroelectric and ferromagnetic (or ferrimagnetic)
+orderings is still lacking. Here, we propose that hydrogen intercalation in
+antiferromagnetic transition metal oxides is a promising way to realize
+multiferroics with strong magnetoelectric coupling. Taking brownmillerite
+SrCoO2.5 as an example, we show that hydrogen intercalated SrCoO2.5 displays
+strong ferrimagnetism and large electric polarization in which the hydroxide
+acts as a new knob to simultaneously control the magnetization and polarization
+at room temperature. We expect that ion intercalation will become a general way
+to design magnetoelectric and spintronic functional materials.",1810.06357v1
+2018-10-20,Evidence for Intra-Unit Cell Magnetism in Superconducting Cuprates: a Technical Assessment,"Intra unit cell (IUC) magnetic order observed by polarized neutron
+diffraction (PND) is one of the hallmarks of the pseudogap state of
+high-temperature copper oxide superconductors. This experimental observation,
+usually interpreted as a result of loop currents, has been recently challenged
+based on lower statistics data. We here address the crucial issue of
+polarization inhomogeneities in the neutron beams showing that the original
+data had a much better reproducibilty. Within these technical limitations, we
+here propose a self-consistent analysis that potentially solves the
+controversy. We show that all the reported PND experiments in superconducting
+cuprates are actually compatible with the existence of an IUC magnetism.",1810.08779v1
+2019-06-18,Indirect Chiral Magnetic Exchange through Dzyaloshinskii-Moriya--Enhanced RKKY Interactions in Manganese Oxide Chains on Ir(100),"Ruderman-Kittel-Kasuya-Yosida interaction even if their wave functions lack
+direct overlap. Theory predicts that spin-orbit scattering leads to a
+Dzyaloshinskii-Moriya type enhancement of this indirect exchange interaction,
+giving rise to chiral exchange terms. Here we present a combined spin-polarized
+scanning tunneling microscopy, angle-resolved photoemission, and density
+functional theory study of MnO$_2$ chains on Ir(100). Whereas we find
+antiferromagnetic Mn--Mn coupling along the chain, the inter-chain coupling
+across the non-magnetic Ir substrate turns out to be chiral with a
+$120^{\circ}$ rotation between adjacent MnO$_2$ chains. Calculations reveal
+that the Dzyaloshinskii-Moriya interaction results in spin spirals with a
+periodicity in agreement with experiment. Our findings confirm the existence of
+indirect chiral magnetic exchange, potentially giving rise to exotic phenomena,
+such as chiral spin-liquid states in spin ice systems or the emergence of new
+quasiparticles.",1906.07703v1
+2019-07-23,FeTe$_{0.55}$Se$_{0.45}$ van der Waals Tunneling Devices,"We report on fabrication of devices integrating FeTe$_{0.55}$Se$_{0.45}$ with
+other van-der-Waals materials, measuring transport properties as well as
+tunneling spectra at variable magnetic fields and temperatures down to 35 mK.
+Transport measurements are reliable and repeatable, revealing temperature and
+magnetic field dependence in agreement with prior results, confirming that
+fabrication processing does not alter bulk properties. However, cross-section
+scanning transmission microscopy reveals oxidation of the surface, which may
+explain a lower yield of tunneling device fabrication. We nonetheless observe
+hard-gap planar tunneling into FeTe$_{0.55}$Se$_{0.45}$ through a MoS$_2$
+barrier. Notably, a minimal hard gap of 0.5 meV persists up to a magnetic field
+of 9 T in the $ab$ plane and 3 T out of plane. This may be the result of very
+small junction dimensions, or a quantum-limit minimal energy spacing between
+vortex bound states. We also observed defect assisted tunneling, exhibiting
+bias-symmetric resonant states which may arise due to resonant Andreev
+processes.",1907.09758v1
+2019-09-10,Spin Pumping from Permalloy into Uncompensated Antiferromagnetic Co doped Zinc Oxide,"Heterostructures of Co-doped ZnO and Permalloy were investigated for their
+static and dynamic magnetic interaction. The highly Co-doped ZnO is
+paramagentic at room temperature and becomes an uncompensated antiferromagnet
+at low temperatures, showing a narrowly opened hysteresis and a vertical
+exchange bias shift even in the absence of any ferromagnetic layer. At low
+temperatures in combination with Permalloy an exchange bias is found causing a
+horizontal as well as vertical shift of the hysteresis of the heterostructure
+together with an increase in coercive field. Furthermore, an increase in the
+Gilbert damping parameter at room temperature was found by multifrequency FMR
+evidencing spin pumping. Temperature dependent FMR shows a maximum in magnetic
+damping close to the magnetic phase transition. These measurements also
+evidence the exchange bias interaction of Permalloy and long-range ordered
+Co-O-Co structures in ZnO, that are barely detectable by SQUID due to the
+shorter probing times in FMR.",1909.04362v3
+2019-09-12,Temperature and field evolution of site-dependent magnetism in $ε$-Fe$_2$O$_3$ nanoparticles,"8~nm epsilon-Fe2O3 nanoparticles exhibit a spin reorientation transition that
+begins at 150 K which is a hallmark of this unique iron-oxide polymorph. We
+find that the change from the high to low temperature magnetic structures has
+been suppressed by ~50 K. At the spin reorientation temperature, a change of
+the field-dependent response of the tetrahedral sites in intermediate field
+strengths (0.25 - 1.5 T) indicates that a collective tetrahedral distortion
+occurs to which the octahedral sites adjust, altering the magnetic anisotropy.
+An abrupt step in the hyperfine parameters' temperature dependencies,
+especially at 125 K for the hyperfine field associated with the Fe4 tetrahedral
+sites, suggests strongly a change in the superexchange pathways are responsible
+for the spin reorientation.",1909.05763v1
+2020-12-14,Correlation-Induced Octahedral Rotations in SrMoO$_3$,"Distortions of the oxygen octahedra influence the fundamental electronic
+structure of perovskite oxides, such as their bandwidth and exchange
+interactions. Utilizing a fully ab-initio methodology based on density
+functional theory plus dynamical mean field theory (DFT+DMFT), we study the
+crystal and magnetic structure of SrMoO$_3$. Comparing our results with DFT+$U$
+performed on the same footing, we find that DFT+$U$ overestimates the
+propensity for magnetic ordering, as well as the octahedral rotations, leading
+to a different ground state structure. This demonstrates that structural
+distortions can be highly sensitive to electronic correlation effects, and to
+the considered magnetic state, even in a moderately correlated metal such as
+SrMoO$_3$. Moreover, by comparing different downfolding schemes, we demonstrate
+the robustness of the DFT+DMFT method for obtaining structural properties,
+highlighting its versatility for applications to a broad range of materials.",2012.07871v2
+2020-12-15,Advanced materials for magnetic cooling:fundamentals and practical aspects,"Over the last two decades, the research activities on magnetocalorics have
+been exponentially increased leading to the discovery of a wide category of
+materials including intermetallics and oxides. Even though the reported
+materials were found to show excellent magnetocaloric properties on laboratory
+scale, only a restricted family among them could be upscaled toward industrial
+levels and implemented as refrigerants in magnetic cooling devices. On the
+other hand, in the most of reported reviews, the magnetocaloric materials are
+usually discussed in terms of their adiabatic temperature and entropy changes,
+which is not enough to get more insight about their large scale applicability.
+In this review, not only the fundamental properties of recently reported
+magnetocaloric materials are discussed but also their thermodynamic performance
+in functional devices. The reviewed families particularly include Gd1-xRx
+alloys, LaFe13-xSix, MnFeP1-xAsx and R1-xAxMnO3 based compounds. Other relevant
+practical aspects such as mechanical stability, synthesis and corrosion issues
+are discussed. In addition, the intrinsic and extrinsic parameters that play a
+crucial role in the control of magnetic and magnetocaloric properties are
+regarded. In order to reproduce the needed magnetocaloric parameters, some
+practical models are proposed. Finally, the concepts of the rotating
+magnetocaloric effect and multilayered magnetocalorics are introduced.",2012.08176v1
+2020-12-18,Competing magnetic orders and multipolar Weyl fermions in 227 pyrochlore iridates,"Owing to comparably strong spin-orbit coupling and Hubbard interaction,
+iridium based 227 pyrochlore oxides harbor a rich confluence of competing
+magnetic orders and emergent multipolar Weyl quasiparticles. Here we show that
+this family of materials is predominantly susceptible toward the nucleation of
+electronic noncoplanar all-in all-out (AIAO) and three-in one-out (3I1O)
+orders, respectively transforming under the singlet $A_{2u}$ and triplet
+$T_{1u}$ representations, supporting octupolar and dipolar Weyl fermions, and
+favored by strong on-site Hubbard and nearest-neighbor ferromagnetic
+interaction. Furthermore, a coplanar magnetic order generically appears as an
+intermediate phase between them. This order transforms under the triplet
+$T_{2u}$ representation and also hosts octupolar Weyl fermions. With the AIAO
+and 3I1O phases possibly being realized in (Nd$_{1-x}$Pr$_{x}$)$_2$Ir$_2$O$_7$
+when $x=0$ and 1, respectively, the intervening $T_{2u}$ order can in principle
+be found at an intermediate doping ($0<x<1$) or in pressured (hydrostatic)
+Nd$_2$Ir$_2$O$_7$.",2012.10442v2
+2017-09-21,Structurally Triggered Metal-Insulator Transition in Rare-Earth Nickelates,"Rare-earth nickelates form an intriguing series of correlated perovskite
+oxides. Apart from LaNiO3, they exhibit on cooling a sharp metal-insulator
+electronic phase transition, a concurrent structural phase transition and a
+magnetic phase transition toward an unusual antiferromagnetic spin order.
+Appealing for various applications, full exploitation of these compounds is
+still hampered by the lack of global understanding of the interplay between
+their electronic, structural and magnetic properties. Here, we show from
+first-principles calculations that the metal-insulator transition of nickelates
+arises from the softening of an oxygen breathing distortion, structurally
+triggered by oxygen-octahedra rotation motions. The origin of such a rare
+triggered mechanism is traced back in their electronic and magnetic properties,
+providing a united picture. We further develop a Landau model accounting for
+the evolution of the metal-insulator transition in terms of the $R cations and
+rationalising how to tune this transition by acting on oxygen rotation motions.",1709.07240v1
+2018-03-06,Effect of charge ordering on the electrical properties and magnetoresistance of manganites,"The Monte Carlo Ferromagnetic Ising model was used to study the electrical
+properties of manganese oxides due to the charge ordering phase occurring at
+doping, x = 0.5. The half-doped manganites have an insulator antiferromagnetic
+ground state. We calculated the internal energy, specific heat, resistivity and
+the magneto-resistance, MR, with parallel and anti-parallel applied magnetic
+fields. Our simulation reveals that the resistivity decreases exponentially and
+the electric current increases with increasing temperature according the free
+charge increase, to transport from an insulator to conductor phase. The
+magnetoresistance has negative small values with parallel magnetic field but
+has positive high values with unti-parallel magnetic field. The obtained
+semiconductor-metal transition behavior candidates the half-doped manganites to
+be very good semiconductors diode junctions.",1803.02283v1
+2018-03-27,Magneto-Electric Effect in a Spin-State Transition System,"Magnetic, dielectric, and magnetoelectric properties in a spin-state
+transition system are examined, motivated by the recent discovery of a
+multiferroic behavior in a cobalt oxide. We construct an effective model
+Hamiltonian based on the two-orbital Hubbard model, in which the spin-state
+degrees of freedom in magnetic ions couple with ferroelectric-type lattice
+distortions. A phase transition occurs from the high-temperature low-spin phase
+to the low-temperature high-spin ferroelectric phase with accompanying an
+increase of the spin entropy. The calculated results are consistent with the
+experimental pressure-temperature phase diagram. We predict the magnetic-field
+induced electric polarization in the low-spin paraelectric phase near the
+ferroelectric phase boundary.",1803.09881v1
+2018-06-06,Anomalous Antiferromagnetism in Metallic RuO$_2$ Determined by Resonant X-ray Scattering,"We studied the magnetic ordering of thin films and bulk crystals of rutile
+RuO$_2$ using resonant X-ray scattering across the Ru L$_2$ absorption edge.
+Combining polarization analysis and azimuthal-angle dependence of the magnetic
+Bragg signal, we have established the presence of G-type antiferromagnetism in
+RuO$_2$ with T$_N$ $>$ 300 K. In addition to revealing a spin-ordered ground
+state in the simplest ruthenium oxide compound, the persistence of magnetic
+order even in nanometer-thick films lays the ground for potential applications
+of RuO$_2$ in antiferromagnetic spintronics.",1806.02036v3
+2018-06-11,Giant perpendicular magnetic anisotropy in Fe/III-V nitride thin films,"Large perpendicular magnetic anisotropy (PMA) in transition metal thin films
+provides a pathway for enabling the intriguing physics of nanomagnetism and
+developing broad spintronics applications. After decades of searches for
+promising materials, the energy scale of PMA of transition metal thin films,
+unfortunately, remains only about 1 meV. This limitation has become a major
+bottleneck in the development of ultradense storage and memory devices. We
+discovered unprecedented PMA in Fe thin-film growth on the $(000\bar{1})$
+N-terminated surface of III-V nitrides from first-principles calculations. PMA
+ranges from 24.1 meV/u.c. in Fe/BN to 53.7 meV/u.c. in Fe/InN.
+Symmetry-protected degeneracy between $x^2-y^2$ and $xy$ orbitals and its lift
+by the spin-orbit coupling play a dominant role. As a consequence, PMA in
+Fe/III-V nitride thin films is dominated by first-order perturbation of the
+spin-orbit coupling, instead of second-order in conventional transition
+metal/oxide thin films. This game-changing scenario would also open a new field
+of magnetism on transition metal/nitride interfaces.",1806.04162v1
+2018-07-25,Role of interfaces in the biased composition of TbFe(Co) thin films,"Ferrimagnetic TbFe or TbFeCo amorphous alloy thin films have been grown by
+co-evaporation in ultra-high vacuum. They exhibit an out-of-plane magnetic
+anisotropy up to their Curie temperature with a nucleation and propagation
+reversal mechanism suitable for current induced domain wall motion. Rutherford
+back scattering experiments confirmed a fine control of the Tb depth-integrated
+composition within the evaporation process. However, a large set of
+experimental techniques were used to evidence an interface related contribution
+in such thin films as compared to much thicker samples. In particular, scanning
+transmission electron microscopy experiments evidence a depth dependent
+composition and perturbed top and bottom interfaces with preferential oxidation
+and diffusion of terbium. Despite of that, amorphous and homogeneous alloy film
+remains in a bulk-like part. The composition of that bulk-like part of the
+magnetic layer, labeled as effective composition, is biased when compared with
+the depth-integrated composition. The magnetic properties of the film are
+mostly dictated by this effective composition, which we show changes with
+different top and bottom interfaces.",1807.09570v1
+2019-08-06,Spectral properties of spin-orbital polarons as a fingerprint of orbital order,"Transition metal oxides are a rich group of materials with very interesting
+physical properties that arise from the interplay of the charge, spin, orbital,
+and lattice degrees of freedom. One interesting consequence of this,
+encountered in systems with orbital degeneracy, is the coexistence of long
+range magnetic and orbital order, and the coupling between them. In this paper
+we develop and study an effective spin-orbital superexchange model for $e_g^3$
+systems and use it to investigate the spectral properties of a charge (hole)
+injected into the system, which is relevant for photoemission spectroscopy.
+Using an accurate, semi-analytical, magnon expansion method, we gain insight
+into various physical aspects of these systems and demonstrate a number of
+subtle effects, such as orbital to magnetic polaron crossover, the coupling
+between orbital and magnetic order, as well as the orbital order driving the
+system towards one-dimensional quantum spin liquid behavior. Our calculations
+also suggest a potentially simple experimental verification of the character of
+the orbital order in the system, something that is not easily accessible
+through most experimental techniques.",1908.02232v1
+2020-03-24,Electric-field-controllable high-spin SrRuO3 driven by a solid ionic junction,"Controlling magnetism and spin structures in strongly correlated systems by
+using electric field is of fundamental importance but challenging. Here, a
+high-spin ruthenate phase is achieved via a solid ionic chemical junction at
+SrRuO3/SrTiO3 interface with distinct formation energies and diffusion barriers
+of oxygen vacancies, analogue to electronic band alignment in semiconductor
+heterojunction. Oxygen vacancies trapped within this interfacial SrRuO3
+reconstruct Ru-4d electronic structure and orbital occupancy, leading to an
+enhanced magnetic moment. Furthermore, an interfacial magnetic phase can be
+switched reversibly by electric-field-rectifying oxygen migration in a
+solid-state ionic gating device, providing a framework for atomic design of
+functionalities in strongly correlated oxides using a way of solid chemistry.",2003.11050v1
+2020-03-30,Spontaneous Rotation of Ferrimagnetism Driven by Antiferromagnetic Spin Canting,"Spin-reorientation phase transitions that involve the rotation of a
+crystal$'$s magnetization have been well characterized in distorted-perovskite
+oxides such as the orthoferrites. In these systems spin reorientation occurs
+due to competing rare-earth and transition metal anisotropies coupled via
+$f$-$d$ exchange. Here, we demonstrate an alternative paradigm for spin
+reorientation in distorted perovskites. We show that the
+$R_2\mathrm{CuMnMn_4O_{12}}$ (R = Y or Dy) triple A-site columnar-ordered
+quadruple perovskites have three ordered magnetic phases and up to two
+spin-reorientation phase transitions. Unlike the spin-reorientation phenomena
+in other distorted perovskites, these transitions are independent of rare-earth
+magnetism, but are instead driven by an instability towards antiferromagnetic
+spin canting likely originating in frustrated Heisenberg exchange interactions,
+and the competition between Dzyaloshinskii-Moriya and single-ion anisotropies.",2003.13774v1
+2020-08-21,Robust anomalous metallic states and vestiges of self duality in two-dimensional granular In-InOx composites,"Many experiments investigating magnetic field tuned superconductor-insulator
+transition (H-SIT), often exhibit low-temperature resistance saturation, which
+is interpreted as an anomalous metallic phase emerging from a ""failed
+superconductor,"" thus challenging conventional theory. Here we study a random
+granular array of indium islands grown on a gateable layer of indium-oxide. By
+tuning the intergrain couplings, we reveal a wide range of magnetic fields
+where resistance saturation is observed, under conditions of careful
+electromagnetic filtering and within a wide range of linear response. Exposure
+to external broadband noise or microwave radiation is shown to strengthen the
+tendency of superconductivity, where at low field a global superconducting
+phase is restored. Increasing magnetic field unveils an ""avoided H-SIT,"" that
+exhibits granularity-induced logarithmic divergence of the
+resistance/conductance above/below that transition, pointing to possible
+vestiges of the original emergent duality observed in a true H-SIT. We conclude
+that anomalous metallic phase is intimately associated with inherent
+inhomogeneities, exhibiting robust behavior at attainable temperatures for
+strongly granular two-dimensional systems.",2008.09325v2
+2020-11-06,Electrical conduction of Ti/TiOx/Ti structures at low temperatures and high magnetic fields,"We present results of electrical conduction studies of Ti/TiOx/Ti planar
+structures prepared by tip-induced local anodic oxidation (LAO) of titanium
+thin films. The prepared structures have shown almost linear I-V curves at
+temperatures between 300 K and 30 K, and only slight deviation from linear
+behaviour at lower temperatures. Electrical conductance of the structures can
+be adequately explained by a two-channel model where variable range hopping
+channels and metallic ones coexist in parallel, while a crossover from Mott to
+Efros-Shklovskii variable-range-hopping conductivity has been observed at
+decreasing temperature. The magnetoresistance of the studied structures is very
+small even in magnetic fields up to 9 T. The reported electrical properties of
+the structures indicate their promising applications as very low heat capacity
+temperature sensors for cryogenic region and high magnetic fields.",2011.03253v1
+2020-11-30,Monopole matter from magnetoelastic coupling in the Ising pyrochlore,"Ising models on a pyrochlore oxide lattice are usually associated with spin
+ice materials and ""magnetic monopoles"". Ever more often effects connecting
+magnetic and elastic degrees of freedom are reported on these and other related
+frustrated materials. Here we extend a spin-ice Hamiltonian to include coupling
+between spins and the O$^{-2}$ ions mediating superexchange; we call it the
+Magnetoelastic Spin Ice model (MeSI). There has been a long search for a model
+in which monopoles would spontaneously become the building blocks of new
+ground-states: the MeSI Hamiltonian is such a model. In spite of its simplicity
+and classical approach, it describes (both spin and oxygen lattice) the
+double-layered monopole crystal observed in Tb$_2$Ti$_2$O$_7$. Remarkably, the
+dipolar electric moment of single monopoles emerges as a probe for magnetism.
+As an example we show that, in principle, pinch points related to Coulomb
+phases could be detected in association with the O$^{-2}$-ion displacements.",2011.15017v1
+2021-02-02,First-principles characterization of the magnetic properties of Cu$_2$(OH)$_3$Br,"Low dimensional spin-1/2 transition metal oxides and oxyhalides continue to
+be at the forefront of research investigating nonclassical phases such as
+quantum spin liquids. In this study, we examine the magnetic properties of the
+oxyhalide $\text{Cu}_2\text{(OH)}_3\text{Br}$ in the botallackite structure
+using first-principles density functional theory, linear spin-wave theory, and
+exact diagonalization calculations. This quasi-2D system consists of
+$\text{Cu}^{2+}$ $\mathrm{S} = 1/2$ moments arranged on a distorted triangular
+lattice. Our exact diagonalization calculations, which rely on a
+first-principles-based magnetic model, generate spectral functions consistent
+with inelastic neutron scattering (INS) data. By performing computational
+experiments to disentangle the chemical and steric effects of the halide ions,
+we find that the dominant effect of the halogen ions is steric in the
+$\text{Cu}_2\text{(OH)}_3\text{X}$ series of compounds.",2102.01542v1
+2021-02-16,Magnetic phase diagram of rare-earth orthorhombic perovskite oxides,"Spin reorientation and magnetisation reversal are two important features of
+the rare-earth orthorhombic provskites ($RM$O$_{3}$'s) that have attracted a
+lot of attention, though their exact microscopic origin has eluded researchers.
+Here, using density functional theory and classical atomistic spin dynamics we
+build a general Heisenberg magnetic model that allows to explore the whole
+phase diagram of the chromite and ferrite compounds and to scrutinize the
+microscopic mechanism responsible for spin reorientations and magnetisation
+reversals. We show that the occurrence of a magnetization reversal transition
+depends on the relative strength and sign of two interactions between
+rare-earth and transition-metal atoms: superexchange and Dzyaloshinsky-Moriya.
+We also conclude that the presence of a smooth spin reorientation transition
+between the so-called $\Gamma_4$ and the $\Gamma_2$ phases through a coexisting
+region, and the temperature range in which it occurs, depends on subtle balance
+of metal--metal (superexchange and Dzyaloshinsky-Moriya) and metal--rare-earth
+(Dzyaloshinsky-Moriya) couplings. In particular, we show that the intermediate
+coexistence region occurs because the spin sublattices rotate at different
+rates.",2102.08152v1
+2021-03-16,Large Enhancement of Ferro-Magnetism under Collective Strong Coupling of YBCO Nanoparticles,"Light-matter strong coupling in the vacuum limit has been shown to enhance
+material properties over the past decade. Oxide nanoparticles are known to
+exhibit weak ferromagnetism due to vacancies in the lattice. Here we report the
+700-fold enhancement of the ferromagnetism of YBa$_2$Cu$_3$O$_{7-x}$
+nanoparticles under cooperative strong coupling at room temperature. The
+magnetic moment reaches 0.90 $\mu_{\rm B}$/mol, and with such a high value, it
+competes with YBa$_2$Cu$_3$O$_{7-x}$ superconductivity at low temperature. This
+strong ferromagnetism at room temperature suggest that strong coupling is a new
+tool for the development of next generations of magnetic and spintronic
+nanodevices.",2103.09331v2
+2021-05-19,Structural and Morphological Effect of Ti underlayer on Pt/Co/Pt Magnetic Ultra-Thin Film,"Pt(x{\AA})/Co(5{\AA})/Pt(10{\AA}) trilayer films were deposited on naturally
+oxidized Si(111) substrate to investigate Ti underlayer effect on PMA. A small
+amount of Ti underlayer promoted the magnetic anisotropy to a perpendicular
+direction for x=8{\AA} and 10{\AA}. Both GI XRD and STM results showed that the
+Ti underlayer manipulated the growth of trilayer film. The Pt particles
+preferably grow the neighborhood of the Ti cluster, giving rise to a relatively
+smooth layer with a fiber texture fcc (111) structure. By contrast, the absence
+of Ti underlayer leads to clustered, relatively rough, and randomly oriented
+nano-crystalline growth. Differences in the growth mode, especially roughness,
+also appeared as intensity loss in XPS spectra due to shadowing effects. Our
+results indicate that a traceable amount of underlayer can change the magnetic
+anisotropy of the film by manipulating film growth.",2105.09355v1
+2021-06-02,Ultrafast demagnetization in NiCo2O4 thin films probed by time-resolved microscopy,"Using a time-resolved magneto-optical Kerr effect (TR-MOKE) microscope, we
+observed ultrafast demagnetization of inverse-spinel-type NiCo2O4 (NCO)
+epitaxial thin films of the inverse spinel type ferrimagnet NCO with
+perpendicular magnetic anisotropy. This microscope uses a pump-probe method,
+where the sample is pumped at 1030 nm, and magnetic domain images are acquired
+via MOKE microscopy at 515 nm (the second harmonic). We successfully observed
+the dynamics of the magnetic domain of the NCO thin film via laser irradiation,
+and obtained a demagnetization time constant of approximately 0.4 ps. This time
+constant was significantly smaller than the large time constants reported for
+other half-metallic oxides. These results, combined with the results of our
+x-ray photoemission spectroscopy study, indicate that this NCO thin film is a
+ferrimagnetic metal whose electronic structure deviates from the theoretically
+predicted half-metallic one.",2106.01026v2
+2021-06-24,Magnon Transport in the Presence of Antisymmetric Exchange in a Weak Antiferromagnet,"The Dzyaloshinskii-Moriya interaction (DMI) is at the heart of many modern
+developments in the research field of spintronics. DMI is known to generate
+noncollinear magnetic textures, and can take two forms in antiferromagnets:
+homogeneous or inter-sublattice, leading to small, canted moments and
+inhomogeneous or intra-sublattice, leading to formation of chiral structures.
+In this work, we first determine the strength of the effective field created by
+the DMI, using SQUID based magnetometry and transport measurements, in thin
+films of the antiferromagnetic iron oxide hematite, $\alpha$-Fe$_2$O$_3$. We
+demonstrate that DMI additionally introduces reconfigurability in the long
+distance magnon transport in these films under different orientations of a
+magnetic field. This arises as a hysteresis centred around the easy-axis
+direction for an external field rotated in opposing directions whose width
+decreases with increasing magnetic field as the Zeeman energy competes with the
+effective field created by the DMI.",2106.12853v2
+2021-09-01,Epitaxial Integration of a Perpendicularly Magnetized Ferrimagnetic Metal on a Ferroelectric oxide for Electric-Field Control,"Ferrimagnets, which contain the advantages of both ferromagnets (detectable
+moments) and antiferromagnets (ultrafast spin dynamics), have recently
+attracted great attention. Here we report the optimization of epitaxial growth
+of a tetragonal perpendicularly magnetized ferrimagnet Mn2Ga on MgO. Electrical
+transport, magnetic properties and the anomalous Hall effect (AHE) were
+systematically studied. Furthermore, we successfully integrated high-quality
+epitaxial ferrimagnetic Mn2Ga thin films onto ferroelectric PMN-PT single
+crystals with a MgO buffer layer. It was found that the AHE of such a
+ferrimagnet can be effectively modulated by a small electric field over a large
+temperature range in a nonvolatile manner. This work thus demonstrates the
+great potential of ferrimagnets for developing high-density and low-power
+spintronic devices.",2109.00169v1
+2021-10-09,Field induced spin freezing and low temperature heat capacity of disordered pyrochlore oxide Ho$_{2}$Zr$_{2}$O$_{7}$,"Spin ice materials are the model systems that have a zero-point entropy as
+\textit{T} $\rightarrow$ 0 K, owing to the frozen disordered states. Here, we
+chemically alter the well-known spin ice Ho$_{2}$Ti$_{2}$O$_{7}$ by replacing
+Ti sites with isovalent but larger Zr ion. Unlike the Ho$_{2}$Ti$_{2}$O$_{7}$
+which is a pyrochlore material, Ho$_{2}$Zr$_{2}$O$_{7}$ crystallizes in
+disordered pyrochlore structure. We have performed detailed structural, ac
+magnetic susceptibility and heat capacity studies on Ho$_{2}$Zr$_{2}$O$_{7}$ to
+investigate the interplay of structural disorder and frustrated interactions.
+The zero-field ground state exhibits large magnetic susceptibility and remains
+dynamic down to 30 mK without showing Pauling's residual entropy. The dynamic
+state is suppressed continuously with the magnetic field and freezing
+transition evolves ($\sim$ 10 K) at a field of $\sim$ 10 kOe. These results
+suggest that the alteration of chemical order and local strain in
+Ho$_{2}$Ti$_{2}$O$_{7}$ prevents the development of spin ice state and provides
+a new material to study the geometrical frustration based on the structure.",2110.04555v1
+2021-10-25,Phonon Anomaly In 9R-Ba0.9Sr0.1MnO3,"Materials which possess coupling between different degrees of freedom such as
+charge, spin, orbital and lattice are of tremendous interest due to their
+potential for device applications. It has been recently realized that some of
+manganite perovskite oxides show structural and ferroelectric instabilities
+which may be tuned by imposing internal or external strain. Among manganite
+perovskites, AMnO3 (A = Ca, Sr and Ba) are reported to be good candidates to
+show spin-phonon coupling driven multiferroicity. Here, we have probed the
+correlation between vibrational and magnetic properties in the 9R-type
+hexagonal Ba0.9Sr0.1MnO3 (BSM10). Nine Raman active modes are observed which
+are characteristic phonon modes for 9R phase. The frequency ({omega}) of an Eg
+(344 cm-1) mode which is related to Mn vibrations shows anomaly with
+temperature (T) manifested as a change in slope of {omega} vs T at 260 K. The
+temperature-dependent magnetization of BSM10 suggests a possible
+antiferromagnetic ordering at ~ 260 K. We, therefore, attribute the phonon
+anomaly to spin-phonon coupling arising due to the magnetic ordering.",2110.13808v1
+2021-12-18,Enhanced Tunnel magnetoresistance in Fe/Mg4Al-Ox/Fe(001) Magnetic Tunnel Junctions,"Spinel MgAl2O4 and family oxides are emerging barrier materials useful for
+magnetic tunnel junctions (MTJs). We report large tunnel magnetoresistance
+(TMR) ratios up to 429% at room temperature (RT) and 1,034% at 10 K in a
+Fe/MgAl2O4/Fe(001)-based MTJ prepared using electron-beam evaporation of
+Mg4Al-Ox. Resistance oscillations with a MTJ barrier thickness of 0.3-nm were
+significantly enhanced compared to those of a Fe/MgO/Fe(001) MTJ, resulting in
+a large TMR oscillation peak-to-valley difference of 125% at RT. The
+differential conductance spectra were symmetric with bias polarity, and the
+spectrum in the parallel magnetization state at low temperature demonstrate
+significant peaks within broad local minima at |0.2-0.6| V, indicating improved
+barrier interfaces by the Mg4Al-Ox barrier. This study demonstrates that TMR
+ratios in Fe(001)-MTJs can still be improved.",2112.09910v1
+2021-12-22,The Preliminary design of DC Magnet Power Supply System for ITER Static Magnetic Field Test facility,"ITER (International Thermonuclear Experimental Reactor) static magnetic field
+(SMF) test facility requires a DC power supply with low voltage, high current,
+and high stability. Due to the limitation ofswitching loss, there is a
+contradiction between the output current capability and the output ripple.
+Large output current usually leads to low switching frequency, and low
+switching frequency will generate a large number of harmonics. To solve the
+problems, a topology based on the interleaving parallel buck converter is used
+and tested in this paper. Moreover, the topology is realized with only a small
+number of switching metal-oxide-semiconductor field effect transistors
+(MOSFETs). This article introduces the system design scheme and control method
+in detail. The analysis of harmonic and simulation are carried out. The
+validity of proposed scheme and control strategy were confirmed by experiments,
+the power supply system can supply large current of 15kA and has ability of low
+ripple.",2112.13669v2
+2022-02-03,Unconventional interlayer exchange coupling via chiral phonons in synthetic magnetic oxide heterostructures,"Chiral symmetry breaking of phonons plays an essential role in emergent
+quantum phenomena owing to its strong coupling to spin degree of freedom.
+However, direct experimental evidence of the chiral phonon-spin coupling is
+lacking. In this study, we report a chiral phonon-mediated interlayer exchange
+interaction in atomically controlled ferromagnetic metal (SrRuO3)-nonmagnetic
+insulator (SrTiO3) heterostructures. Owing to the unconventional interlayer
+exchange interaction, we have observed rotation of magnetic moments as a
+function of nonmagnetic insulating spacer thickness, resulting in a spin spiral
+state. The chiral phonon-spin coupling is further confirmed by phonon Zeeman
+effects. The existence of the chiral phonons and their interplay with spins
+along with our atomic-scale heterostructure approach open a window to unveil
+the crucial roles of chiral phonons in magnetic materials.",2202.01447v1
+2022-03-04,Simultaneous optical trapping and magnetic micromanipulation of ferromagnetic iron-doped upconversion microparticles in six degrees of freedom,"Optical trapping of magnetic Fe-oxide particles is notoriously difficult due
+to their high refractive indices, not to mention high absorptivity at the
+trapping infra-red wavelengths. We synthesize Fe co-doped NaYF4:Yb,Er
+ferromagnetic upconversion particles that not only have refractive indices
+conducive for optical trapping, but also heat less than Haematite particles at
+off-resonant wavelengths. These particles are hexagonal shaped with dimensions
+of the order of 3 micrometer and also bear high coercivity of 20 mT and
+saturation magnetisation of 1 Am^2/kg. This enables simultaneous use of optical
+trapping and magnetic forces to generate micro-manipulation in all the six
+degrees of freedom of a rigid body. We also show that these particles heat
+significantly when illuminated on absorption resonance at 975 nm while emitting
+visible light with possible implications for fluorescence microscopy and
+photothermal therapy of cancer cells.",2203.02152v2
+2022-04-04,Hole-doping induced ferromagnetism in 2D materials,"Two-dimensional (2D) ferromagnetic materials are considered as promising
+candidates for the future generations of spintronic devices. Yet, 2D materials
+with intrinsic ferromagnetism are scarce. High-throughput first-principles
+simulations are performed in order to screen 2D materials that present a
+non-magnetic to a ferromagnetic transition upon hole doping. A global
+evolutionary search is subsequently performed, in order to identify alternative
+possible atomic structures of the eligible candidates, and 122 materials
+exhibiting a hole-doping induced ferromagnetism are identified. Their energetic
+and dynamic stability, as well as their magnetic properties under hole doping
+are investigated systematically. Half of these 2D materials are metal halides,
+followed by chalcogenides, oxides and nitrides, some of them having predicted
+Curie temperatures above 300 K. The exchange interactions responsible for the
+ferromagnetic order in these 2D materials are also discussed. This work not
+only provides theoretical insights into hole-doped 2D ferromagnetic materials,
+but also enriches the family of 2D magnetic materials for possible spintronic
+applications.",2204.01551v2
+2022-04-27,Magnetic molecule tunnel heterojunctions,"We characterize molecular magnet heterojunctions in which sublimated CoPc
+films as thin as 5 nm are sandwiched between transparent conducting
+bottom-layer indium tin oxide and top-layer soft-landing eutectic GaIn (EGaIn)
+electrodes. The roughness of the cobalt phthalocyanine (CoPc) films was
+determined by atomic force microscopy to be on the order of several nanometers,
+and crystalline ordering of lying-down planar molecules was confirmed by X-ray
+diffraction. The current-voltage (I-V) characteristics reveal the onset of a
+superconducting gap at Tc = 6 K, which together with higher temperature fits to
+a modified Simmons' model, provide incontrovertible evidence for direct quantum
+mechanical tunneling processes through the magnetic molecules in our
+heterojunctions. The voltage dependent features in the differential conductance
+measurements relate to spin states of single molecules or aggregates of
+molecules and should prove to be important for quantum information device
+development.",2204.13152v1
+2022-05-07,Interplay between the extended s-wave symmetry of the gap and the spin-orbit coupling in the low-electron concentration regime of quasi-two-dimensional superconductors,"We analyze the real-space paired state with the $\mathbf{k}$-dependent
+superconducting gap in the presence of Rashba type spin-orbit coupling and
+external magnetic field. We show that the $extended$ $s$-$wave$ pairing
+symmetry is the most probable scenario to appear in the low-electron
+concentration regime. According to our study, the van Hove singularity induced
+by the spin-orbit coupling may lead to a significant enhancement of the
+superconducting gap, critical temperature and critical magnetic field.
+Moreover, the combined effect of the spin-orbit coupling and the external
+magnetic field results in a non-zero total momentum of the Cooper pairs, which
+is a characteristic feature of the so-called helical state. In such situation,
+due to the C$_4$ symmetry breaking, a small $d$-$wave$ and $p$-$wave$
+contributions to the pairing appear, which significantly change the character
+of the helical state. The obtained results are discussed in the context of the
+experimental data related with the unconventional superconducting features of
+the transition metal oxide interfaces as well as the recently reported
+supercurrent diode effect.",2205.03632v3
+2022-06-03,Development of Ni doped SnO$_2$ Dilute magnetic oxides for electronics and spintronics applications,"We used a solid-state reaction method to prepare Sn$_{1-x}$Ni$_x$O$_2$ with
+$x$ = 0, 0.05, 0.1, 0.15 polycrystalline compounds. A rutile phase with
+tetragonal crystal structure was confirmed by X-ray diffraction. At room
+temperature, the magnetisation study shows that the saturation magnetization
+increases with Ni doping content whereas the coercive field decreases after
+$x$=0.1. The spin number increases as the Ni doping concentration increases,
+indicating that the incorporation of Ni into the Sn sites increases the number
+of spins interacting to improve the ferromagnetic phase , which is like
+saturation magnetization and coercive field.",2206.01525v1
+2022-06-08,A multiferroic two-dimensional electron gas,"Multiferroics are compounds in which at least two ferroic orders coexist -
+typically (anti)ferromagnetism and ferroelectricity. While magnetic order can
+arise in both insulating and conducting compounds, ferroelectricity is in
+principle not allowed in metals although a few two-dimensional (semi)metals
+were reported to behave as ferroelectrics. Yet, the combination with magnetic
+order to realize multiferroic metals remains elusive. Here, by combining x-ray
+spectroscopy and magnetotransport, we show the coexistence of ferroelectricity
+and magnetism in an oxide-based two-dimensional electron gas (2DEG). The data
+evidence a non-volatile switching of the polar displacements and of the
+anomalous Hall effect by the polarization direction, demonstrating a
+magnetoelectric coupling. Our findings provide new opportunities in quantum
+matter stemming from the interplay between ferroelectricity, ferromagnetism and
+Rashba spin-orbit coupling in a 2DEG.",2206.03843v1
+2022-10-12,Critical role of magnetic moments on lattice dynamics in YBa${}_{2}$Cu${}_{3}$O${}_{6}$,"The role of lattice dynamics in unconventional high-temperature
+superconductivity is still vigorously debated. Theoretical insights into this
+problem have long been prevented by the absence of an accurate first-principles
+description of the combined electronic, magnetic, and lattice degrees of
+freedom. Utilizing the recently constructed r$^2$SCAN density functional that
+stabilizes the antiferromagnetic (AFM) state of the pristine oxide
+YBa$_2$Cu$_3$O$_6$, we faithfully reproduce the experimental dispersion of key
+phonon modes. We further find significant magnetoelastic coupling in numerous
+high energy Cu-O bond stretching optical branches, where the AFM results
+improve over the soft non-magnetic phonon bands.",2210.06569v2
+2022-11-04,Tunable magnetocaloric effect and enhanced refrigerant capacity in composite-like oxide heterostructures,"We report a detailed study of the magnetocaloric effect in heterostructures
+of La2NiMnO6 and La2/3Sr1/3MnO3. The shape, width and magnitude of the
+temperature dependence of the magnetic entropy change ($\Delta S_{m}$) for
+these multilayer samples can be tuned and controlled by changing their layout.
+A large $\Delta S_{m}$ over a wide temperature range which goes beyond room
+temperature is observed in all samples. We observe a temperature-independent
+table-top-like $\Delta S_{m}$ over a temperature range as large as 100 K in the
+trilayer samples. La2NiMnO6 double perovskite with multiple magnetic phase
+transitions is the key to tuning and shaping the temperature dependence of the
+magnetic entropy changes to suit the requirements of several cooling cycles.",2211.02715v1
+2022-12-01,"Tuning Structural, Transport and Magnetic Properties of Epitaxial SrRuO3 through Ba-Substitution","The perovskite ruthenates (ARuO3, A = Ca, Ba, or Sr) exhibit unique
+properties owing to a subtle interplay of crystal structure and electronic-spin
+degrees of freedom. Here, we demonstrate an intriguing continuous tuning of
+crystal symmetry from orthorhombic to tetragonal (no octahedral rotations)
+phases in epitaxial SrRuO3 achieved via Ba-substitution (Sr1-xBaxRuO3 with 0 <
+x < 0.7). An initial Ba-substitution to SrRuO3 not only changes the
+ferromagnetic properties, but also tunes the perpendicular magnetic anisotropy
+via flattening the Ru-O-Ru bond angle (to 180{\deg}), resulting in the maximum
+Curie temperature and an extinction of RuO6 rotational distortions at x = 0.20.
+For x > 0.2, the suppression of RuO6 octahedral rotational distortion
+dominantly enhances the ferromagnetism in the system, though competing with the
+impact of the RuO6 tetragonal distortion. Further increasing x > 0.2 gradually
+enhances the tetragonal-type distortion, resulting in the tuning of Ru-4d
+orbital occupancy and suppression of ferromagnetism. Our results demonstrate
+that isovalent substitution of the A-site cations significantly and
+controllably impacts both electronic and magnetic properties of perovskite
+oxides.",2212.00267v2
+2022-12-23,Thickness Dependent Itinerant Ferromagnetism in Ultrathin Ba-Doped SrRuO3 films,"The electronic and magnetic properties in ABO3 perovskite oxides are
+extremely sensitive to lattice structure but also the dimensionality, such as
+the thickness in thin film form. Here, we report the thickness-dependent
+electro-magnetic properties of ultrathin epitaxially stabilized Sr1-xBaxRuO3 (x
+= 0.08, 0.2) thin films on SrTiO3 (001) substrate. The results reveal that the
+Ba-doping (0.08 < x < 0.20) reduces RuO6 orthorhombic distortions existing in
+SrRuO3 and induces a tetragonal distortion as evidenced by out-of-plane lattice
+expansion. A metal-to-insulator transition, accompanied by a ferromagnetic to
+non-magnetic transition occurs with reducing film thickness from 10 to 3
+unit-cell (u.c.) for both x = 0.08 and 0.2, regardless of the doping level. The
+results suggest that the effects of compositional vacancies and
+surface/interface contributions introduced via dimensional confinement are more
+dominant than A-site chemical disorder or structural distortion for the loss of
+metallicity and ferromagnetism in ultra-thin epitaxial films.",2212.12120v1
+2023-02-14,MICROSTRUCTURE OF Glidcop AL-60,"Glidcop is an oxide-particle-dispersion strengthened copper composite that
+has a combination of high mechanical strength and high electrical conductivity.
+It has been used as a conductor for 100 T ultrahigh field pulsed magnets by the
+National High Magnetic Field Laboratory, USA. In the quest for even higher
+field pulsed magnets, material development is crucial. Since the mechanical
+properties of a material are often determined by its micro-structure, full
+characterization of the microstructure of Glidcop is necessary. In this work,
+we studied the microstructure of Glidcop AL-60 using both transmission electron
+microscopy (TEM) and scanning transmission electron microscopy (STEM). We
+identified both alpha-Al2O3 and cubic eta-Al2O3 nanoparticles in AL-60 and
+investigated their size and density distribution. The small alumina particles
+eta-Al2O3 nanoparticles with typical size of 5 to 30 nm are of triangular
+shape. They have had well defined crystal orientation relation-ship with the Cu
+matrix. We observed dislocations pinned by the alumina nanoparticles in
+cold-drawn wires. We believed that dislocation bypassing alumina particles via
+Orowan looping was the main strengthening mechanism. We observed microcracks
+near large particles, demonstrating the detrimental effect of large particles
+in AL-60.",2302.08978v1
+2023-02-22,Switchable-magnetisation planar probe MFM sensor,"We present an alternative switching-magnetization magnetic force microscopy
+(SM- MFM) method using planar tip-on-chip probes. Unlike traditional
+needle-like tips, the planar probe approach integrates a microdevice near the
+tip apex with dedicated functionality. Its 1 mm x 1 mm planar surface paves the
+way for freedom in ultra thin-film engineering and micro-/nano-tailoring for
+application-oriented tip functionalization. Here, we form a microscale current
+pathway near the tip end to control tip magnetisation. The chip like probe or
+planar probe, was applied to study the complex magnetic behaviour of epitaxial
+transition metal oxide perovskite LaMnO3, which was previously shown to behave
+as complex material with domains associated with superpara-, antiferro- and
+ferromagnetism. To this end we successfully imaged an inhomogeneous
+distribution of weak ferromagnetic islands with a resolution better than 10 nm.",2302.11387v1
+2023-03-22,Magnetic nanorods for quantitative viscosity imaging using heterodyne holography,"Many processes in microfluidics and biology are driven or affected by
+viscosity. While several methods are able to measure this parameter globally
+(AFM, surface acoustic waves, DLS, ...), very few can provide high resolution
+viscosity images, particularly in living cells. Here, we propose to use
+sub-micrometer magnetic rods to perform high resolution viscosity imaging. An
+external magnetic field forces the oscillation of superparamagnetic iron oxide
+nanorods. Under linearly polarized illumination, the rotation of these highly
+anisotropic optical scatterers induces a blinking which is analyzed by
+heterodyne holography. The spectral analysis of the rotation dynamics yields a
+regime transition frequency f t from which the local viscosity is deduced.
+Holography provides 3D image reconstruction and 3D superlocalization of the
+nanorods, which allows super-resolved viscosity measurements. Relying on the
+fast Brownian rotation of nanorods instead of their slower translation
+therefore allows faster measurements and, crucially, smaller effective voxels
+for viscosity determination. Viscosity imaging is demonstrated with a 0.5
+{\mu}m 3 3D resolution.",2303.12545v1
+2023-03-25,Muon spin relaxation and emergence of disorder-induced unconventional dynamic magnetic fluctuations in Dy$_{2}$Zr$_{2}$O$_{7}$,"The disordered pyrochlore oxide Dy$_{2}$Zr$_{2}$O$_{7}$ shows the signatures
+of field-induced spin freezing with remnant zero-point spin-ice entropy at 5
+kOe magnetic field. We have performed zero-field and longitudinal field Muon
+spin relaxation ($\mu$SR) studies on Dy$_{2}$Zr$_{2}$O$_{7}$. Our zero field
+studies reveal the absence of both long-range ordering and spin freezing down
+to 62 mK. The $\mu$SR relaxation rate exhibits a temperature-independent
+plateau below 4 K, indicating a dynamic ground state of fluctuating spins
+similar to the well-known spin ice system Dy$_{2}$Ti$_{2}$O$_{7}$. The
+low-temperature spin fluctuations persist in the longitudinal field of 20 kOe
+as well and show unusual field dependence of the relaxation rate, which is
+uncommon for a spin-liquid system. Our results, combined with the previous
+studies do not show any evidence of spin ice or spin glass ground state, rather
+point to a disorder-induced dynamic magnetic ground state in the
+Dy$_{2}$Zr$_{2}$O$_{7}$ material.",2303.14426v1
+2023-03-31,Tailoring the interfacial magnetic interaction in epitaxial La$_{0.7}$Sr$_{0.3}$MnO$_3$/Sm$_{0.5}$Ca$_{0.5}$MnO$_3$ heterostructures,"Interface engineering in complex oxide heterostructures has developed into a
+flourishing field as various intriguing physical phenomena can be demonstrated
+which are otherwise absent in their constituent bulk compounds. Here we present
+La$_{0.7}$Sr$_{0.3}$MnO$_3$ (LSMO) / Sm$_{0.5}$Ca$_{0.5}$MnO$_3$ (SCMO) based
+heterostructures showcasing the dominance of antiferromagnetic interaction with
+increasing interfaces. In particular, we demonstrate that exchange bias can be
+tuned by increasing the number of interfaces; while, on the other hand,
+electronic phase separation can be mimicked by creating epitaxial multilayers
+of such robust charge ordered antiferromagnetic (CO-AF) and ferromagnetic (FM)
+manganites with increased AF nature, which otherwise would require
+intrinsically disordered mixed phase materials. The origin of these phenomena
+is discussed in terms of magnetic interactions between the interfacial layers
+of the LSMO/SCMO. A theoretical model has been utilized to account for the
+experimentally observed magnetization curves in order to draw out the complex
+interplay between FM and AF spins at interfaces with the onset of charge
+ordering.",2303.18054v1
+2023-06-23,Electronic structure of RE1-xAxMnO3 manganite films investigated by magnetic circular dichroism spectroscopy,"Magnetic circular dichroism (MCD) spectroscopy was used to study the features
+of the electronic structure of an epitaxial La0.7Ca0.3MnO3 film in the range of
+1.2 - 4 eV. The study of the temperature behavior of the MCD spectra made it
+possible to establish a correlation between the magnetooptical and transport
+properties of the sample. The data obtained were analyzed in comparison with
+MCD data for polycrystalline manganite films of various RE1-xAxMnO3
+compositions. The MCD spectra of the films were compared with the spectra of
+the off-diagonal component of the permittivity tensor calculated from the data
+of the magneto-optical Kerr effect for films of the same composition. A unified
+set of ground and excited electronic states characteristic of RE1-xAxMnO3
+manganites in the visible and near infrared ranges has been identified. These
+results are important for a qualitative theoretical description of the
+electronic structure of strongly correlated magnetic oxides.",2306.13510v1
+2024-03-13,Geometric and electronic properties of two kinds of CrO2 magnetic monolayers: D3d and D2h phases,"Due to the high magnetic coupling strength between the Cr elements, the bulk
+phase CrO2 is one of several ferromagnetic oxides known to have the highest
+Curie temperature. When the dimensionality of the material is reduced from 3D
+to 2D, the 2D CrO2 system material is expected to maintain a high Curie
+temperature. In this work, we predict two new phases of CrO2 monolayer (D3d and
+D2h) by using first-principles calculations. We have found that the Curie
+temperature of 2D CrO2 is much lower than that of its bulk phase, but still
+remains as high as 191K, which is comparable to that of Fe2Cr2Ge6. In addition,
+1L D3d-CrO2 is in the ferromagnetic state, while 1L D2h-CrO2 is in the
+antiferromagnetic state. Also, the different geometric structure affects its
+electrical properties: the 1L D3d-CrO2 is a half-metal while 1L D2h-CrO2 is a
+semiconductor. Our studies have shown that there is a wealth of electrical and
+magnetic properties in CrO2.",2403.08357v1
+2020-08-31,"Structural, magnetic and electronic properties of CaBaCo4-xMxO7 (M= Fe, Zn)","The effect of substituting iron and zinc for cobalt in CaBaCo$_4$O$_7$ has
+been investigated using neutron diffraction and x-ray absorption spectroscopy.
+The orthorhombic distortion present in the parent compound CaBaCo$_4$O$_7$
+decreases with increasing the content of either Fe or Zn. The samples
+CaBaCo$_3$ZnO$_7$ and CaBaCo$_{4-x}$Fe$_x$O$_7$ with $x \leq 1.5$ are
+metrically hexagonal but much better refinements in the neutron diffraction
+patterns are obtained using an orthorhombic unit cell. The two types of
+substitution have opposite effects on the structural and magnetic properties.
+Fe atoms preferentially occupy the sites at the triangular layer. Thus, the
+replacement of Co by Fe supresses the ferrimagnetic ordering and
+CaBaCo$_{4-x}$Fe$_x$O$_7$ samples are antiferromagnetically ordered with a new
+propagation vector k=(1/3,0,0). However, the Zn atoms prefer occupying the
+Kagome layer, which is very detrimental for the long range magnetic
+interactions giving rise to a magnetic glass. The oxidation state of iron and
+zinc is found to be 3+ and 2+, respectively, independently of the content.
+Therefore, the average Co oxidation state changes accordingly with the
+Fe$^{3+}$ or Zn$^{2+}$ doping. Also, x-ray absorption spectroscopy data
+confirms the different preferential occupation for both Fe and Zn cations. The
+combined information obtained by neutron diffraction and x-ray absorption
+spectroscopy indicates that cobalt atoms can be either in a fluctuating
+Co$^{2+}$/Co$^{3+}$ valence state or, alternatively, Co$^{2+}$ and Co$^{3+}$
+ions being randomly distributed in the lattice. These results explain the
+occurrence of local disorder in the CoO$_4$ tetrahedra obtained by EXAFS. An
+anomaly in the lattice parameters and an increase in the local disorder is
+observed only at the ferrimagnetic transition for CaBaCo$_4$O$_7$ revealing the
+occurrence of local magneto-elastic coupling.",2008.13649v1
+2021-04-15,Active Magnetoplasmonics with Transparent Conductive Oxide Nanocrystals,"Magnetoplasmonics is highly promising to devise active optical elements:
+modulating the plasmon resonance condition with magnetic field can boost the
+performance of refractometric sensors and nanophotonic optical devices.
+Nevertheless, real life applications are hampered by the magnetoplasmonic
+trilemma: 1) a good plasmonic metal has sharp optical resonances but low
+magneto-optical response; 2) a magnetic metal has strong magneto-optical
+response but a very broad plasmonic resonance; 3) mixing the two components
+degrades the quality of both features. To overcome the trilemma, we use a
+different class of materials, transparent conductive oxide nanocrystals (NCs)
+with plasmonic response in the near infrared. Although non-magnetic, they
+combine a large cyclotron frequency (due to small electron effective mass) with
+sharp plasmonic resonances. We benchmark the concept with F- and In- doped CdO
+(FICO) and Sn-doped In2O3 (ITO) NCs to boost the magneto-optical Faraday
+rotation and ellipticity, reaching the highest magneto-optical response for a
+non-magnetic plasmonic material, and exceeding the performance of
+state-of-the-art ferromagnetic nanostructures. The magnetoplasmonic response of
+these NCs was rationalized with analytical model based on the excitation of
+circular magnetoplasmonic modes. Finally, proof of concept experiments
+demonstrated the superior performance of FICO NCs with respect to current state
+of the art in magnetoplasmonic refractometric sensing, approaching the
+sensitivity of leading localized plasmon refractometric methods with the
+advantage of not requiring complex curve fitting.",2104.07772v1
+2021-06-15,Low-energy spin dynamics in rare-earth perovskite oxides,"We review recent studies of spin dynamics in rare-earth orthorhombic
+perovskite oxides of the type $RM$O$_3$, where $R$ is a rare-earth ion and $M$
+is a transition-metal ion, using single-crystal inelastic neutron scattering
+(INS). After a short introduction to the magnetic INS technique in general, the
+results of INS experiments on both transition-metal and rare-earth subsystems
+for four selected compounds (YbFeO$_3$, TmFeO$_3$, YFeO$_3$, YbAlO$_3$) are
+presented. We show that the spectrum of magnetic excitations consists of two
+types of collective modes that are well separated in energy: gapped magnons
+with a typical bandwidth of $<$70 meV, associated with the
+antiferromagnetically (AFM) ordered transition-metal subsystem, and AFM
+fluctuations of $<$5 meV within the rare-earth subsystem, with no hybridization
+of those modes. We discuss the high-energy conventional magnon excitations of
+the 3$d$ subsystem only briefly, and focus in more detail on the spectacular
+dynamics of the rare-earth sublattice in these materials. We observe that the
+nature of the ground state and the low-energy excitation strongly depends on
+the identity of the rare-earth ion. In the case of non-Kramers ions, the
+low-symmetry crystal field completely eliminates the degeneracy of the
+multiplet state, creating a rich magnetic field-temperature phase diagram. In
+the case of Kramers ions, the resulting ground state is at least a doublet,
+which can be viewed as an effective quantum spin-1/2. Equally important is the
+fact that in Yb-based materials the nearest-neighbor exchange interaction
+dominates in one direction, despite the three-dimensional nature of the
+orthoperovskite crystal structure. The observation of a fractional spinon
+continuum and quantum criticality in YbAlO$_3$ demonstrates that Kramers
+rare-earth based magnets can provide realizations of various aspects of quantum
+low-dimensional physics.",2106.08378v1
+2022-03-22,Discovery of charge density wave in a correlated kagome lattice antiferromagnet,"A hallmark of strongly correlated quantum materials is the rich phase diagram
+resulting from competing and intertwined phases with nearly degenerate ground
+state energies. A well-known example is the copper oxides, where a charge
+density wave (CDW) is ordered well above and strongly coupled to the magnetic
+order to form spin-charge separated stripes that compete with
+superconductivity. Recently, such rich phase diagrams have also been revealed
+in correlated topological materials. In two-dimensional kagome lattice metals
+consisting of corner-sharing triangles, the geometry of the lattice can produce
+flat bands with localized electrons, non-trivial topology, chiral magnetic
+order, superconductivity and CDW order. While CDW has been found in weakly
+electron correlated nonmagnetic AV3Sb5 (A = K, Rb, Cs), it has not yet been
+observed in correlated magnetic ordered kagome lattice metals. Here we report
+the discovery of CDW within the antiferromagnetic (AFM) ordered phase of kagome
+lattice FeGe. The CDW in FeGe occurs at wavevectors identical to that of
+AV3Sb5, enhances the AFM ordered moment, and induces an emergent anomalous Hall
+effect. Our findings suggest that CDW in FeGe arises from the combination of
+electron correlations-driven AFM order and van Hove singularities-driven
+instability possibly associated with a chiral flux phase, in stark contrast to
+strongly correlated copper oxides and nickelates, where the CDW precedes or
+accompanies the magnetic order.",2203.11467v1
+2010-07-16,Magnetism and Charge Dynamics in Iron Pnictides,"In a wide variety of materials, such as copper oxides, heavy fermions,
+organic salts, and the recently discovered iron pnictides, superconductivity is
+found in close proximity to a magnetically ordered state. The character of the
+proximate magnetic phase is thus believed to be crucial for understanding the
+differences between the various families of unconventional superconductors and
+the mechanism of superconductivity. Unlike the AFM order in cuprates, the
+nature of the magnetism and of the underlying electronic state in the iron
+pnictide superconductors is not well understood. Neither density functional
+theory nor models based on atomic physics and superexchange, account for the
+small size of the magnetic moment. Many low energy probes such as transport,
+STM and ARPES measured strong anisotropy of the electronic states akin to the
+nematic order in a liquid crystal, but there is no consensus on its physical
+origin, and a three dimensional picture of electronic states and its relations
+to the optical conductivity in the magnetic state is lacking. Using a first
+principles approach, we obtained the experimentally observed magnetic moment,
+optical conductivity, and the anisotropy of the electronic states. The theory
+connects ARPES, which measures one particle electronic states, optical
+spectroscopy, probing the particle hole excitations of the solid and neutron
+scattering which measures the magnetic moment. We predict a manifestation of
+the anisotropy in the optical conductivity, and we show that the magnetic phase
+arises from the paramagnetic phase by a large gain of the Hund's rule coupling
+energy and a smaller loss of kinetic energy, indicating that iron pnictides
+represent a new class of compounds where the nature of magnetism is
+intermediate between the spin density wave of almost independent particles, and
+the antiferromagnetic state of local moments.",1007.2867v1
+2019-05-06,"Nonmagnetic substitution in pyrochlore iridate Y$_2$(Ir$_{1-x}$Ti$_{x}$)$_2$O$_7$: Structure, magnetism and electronic properties","Tuning of spin-orbit coupling and electron correlation effects in pyrochlore
+iridates is considered for many interesting phenomena. We have investigated the
+temperature evolution of structural, magnetic and electronic properties in
+doped Y$_2$(Ir$_{1-x}$Ti$_{x}$)$_2$O$_7$ ($x$ = 0.0, 0.02, 0.05, 0.10 and 0.15)
+where the substitution of nonmagnetic Ti$^{4+}$ (3$d^0$) for Ir$^{4+}$ (5$d^5$)
+amounts to dilution of magnetic network and tuning of these parameters in
+opposite way. The system retains its original structural symmetry but local
+structural parameters show an evolution with Ti content. While the magnetic
+transition temperature is not largely influenced, both magnetic moment and
+magnetic frustration decreases with Ti doping. Magnetic relaxation measurement
+shows the parent compound Y$_2$Ir$_2$O$_7$ as well as its Ti doped analogues
+are in nonequilibrium magnetic state where the magnetic relaxation rate
+increases with Ti. Temperature dependent Raman measurements indicate no changes
+in structural symmetry, however, across the magnetic transition temperature an
+anomaly in A$_{1g}$ Raman mode is observed. Temperature dependent x-ray
+diffraction data also support the Raman spectroscopy data, however, an
+evolution of lattice parameters with temperature is observed. The electrical
+resistivity data of Y$_2$(Ir$_{1-x}$Ti$_{x}$)$_2$O$_7$ series exhibits
+insulating behavior throughout the temperature range, however, the resistivity
+decreases with Ti doping. The nature of charge conduction is found to follow
+power-law behavior in whole series but the validity of this model varies with
+temperature. A negative magnetoresistance has been observed at low temperature
+in present series which is explained with weak localized mechanism. Similar to
+other Ir based oxides, a crossover from negative to positive MR has been
+observed in present system.",1905.01951v1
+2011-11-22,Observation of spin glass state in weakly ferromagnetic Sr$_2$FeCoO$_6$ double perovskite,"We report the observation of spin glass state in the double perovskite oxide
+Sr$_{2}$FeCoO$_{6}$ prepared through sol-gel technique. Initial structural
+studies using x rays reveal that the compound crystallizes in tetragonal $I
+4/m$ structure with lattice parameters, $a$ = 5.4609(2) \AA and $c$ = 7.7113(7)
+\AA. The temperature dependent powder x ray studies reveal no structural phase
+transition in the temperature range 10 -- 300 K. However, the unit cell volume
+shows an anomaly coinciding with the magnetic transition temperature thereby
+suggesting a close connection between lattice and magnetism. Neutron
+diffraction studies and subsequent bond valence sums analysis show that in
+Sr$_{2}$FeCoO$_{6}$, the $B$ site is randomly occupied by Fe and Co in the
+mixed valence states of Fe$^{3+}$/Fe$^{4+}$ and Co$^{3+}$/Co$^{4+}$. The random
+occupancy and mixed valence sets the stage for inhomogeneous magnetic exchange
+interactions and in turn, for the spin glass like state in this double
+perovskite which is observed as an irreversibility in temperature dependent dc
+magnetization at $T_f\sim$ 75 K. Thermal hysteresis observed in the
+magnetization profile of Sr$_{2}$FeCoO$_{6}$ is indicative of the mixed
+magnetic phases present. The dynamic magnetic susceptibility displays
+characteristic frequency dependence and confirms the spin glass nature of this
+material. Dynamical scaling analysis of $\chi'(T)$ yields a critical
+temperature $T_{ct}$ = 75.14(8) K and an exponent $z\nu$ = 6.2(2) typical for
+spin glasses. The signature of presence of mixed magnetic interactions is
+obtained from the thermal hysteresis in magnetization of Sr$_{2}$FeCoO$_{6}$.
+Combining the neutron and magnetization results of Sr$_2$FeCoO$_6$, we deduce
+the spin states of Fe to be in low spin while that of Co to be in low spin and
+intermediate spin.",1111.5136v1
+2023-03-19,Quasi One-Dimensional Ising-like Antiferromagnetism in the Rare-earth Perovskite Oxide TbScO$_3$,"The rare-earth perovskite TbScO$_3$ has been widely used as a substrate for
+the growth of epitaxial ferroelectric and multiferroic thin films, while its
+detailed low-temperature magnetic properties were rarely reported. In this
+paper, we performed detailed magnetization, specific heat and single crystal
+neutron scattering measurements, along with the crystalline electric field
+calculations to study the low-temperature magnetic properties of TbScO$_3$. All
+our results suggest the magnetic Tb$^{3+}$ has an Ising-like pseudo-doublet
+ground state at low temperatures. Due to the constrain of local point symmetry,
+these Tb$^{3+}$ Ising moments are confined in the $ab$ plane with a tilt angle
+of $\varphi = \pm48^{\mathrm{o}}$ to the $a$ axis. In zero field, the system
+undergoes an antiferromagnetic phase transition at $T_{\mathrm{N}}=2.53$ K, and
+forms a $G_xA_y$ noncollinear magnetic structure below $T_{\mathrm{N}}$. We
+find the dipole-dipole interactions play an important role to determine the
+magnetic ground state, which are also responsible for the quasi-one-dimensional
+magnetism in TbScO$_3$. The significant anisotropic diffuse scatterings further
+confirm the quasi-one-dimensional magnetism along the $c$ axis. The magnetic
+phase diagram with the field along the easy $b$ axis is well established. In
+addition to the $G_xA_y$ antiferromagnetic state, there is an exotic
+field-induced phase emerged near the critical field $B_{\mathrm{c}}\simeq0.7$
+T, where three-dimensional magnetic order is suppressed but strong
+one-dimensional correlations may still exist.",2303.10578v1
+2004-07-13,Surface oxidation of liquid Sn,"We report the results of an x-ray scattering study that reveals oxidation
+kinetics and formation of a previously unreported crystalline phase of SnO at
+the liquid-vapour interface of Sn. Our experiments reveal that the pure liquid
+Sn surface does not react with molecular oxygen below an activation pressure of
+\~5.0*10-6 Torr. Above that pressure a rough solid Sn oxide grows over the
+liquid metal surface. Once the activation pressure has been exceeded the
+oxidation proceeds at pressures below the oxidation pressure threshold. The
+observed diffraction pattern associated with the surface oxidation does not
+match any of the known Sn oxide phases. The data have an explicit signature of
+the face-centred cubic structure, however it requires lattice parameters that
+are about 9% smaller than those reported for cubic structures of high-pressure
+phases of Sn oxides.
+  Keywords: X-ray scattering, diffraction, and reflection; Oxidation; Surface
+chemical reaction; Surface structure, morphology, roughness, and topography;
+Tin; Tin oxides; Liquid surfaces; Polycrystalline thin films",0407313v1
+2010-03-22,Dissociative adsorption of methane on surface oxide structures of Pd-Pt alloys,"The dissociative adsorption of methane on variously oxidized Pd, Pt and Pd-Pt
+surfaces is investigated using density-functional theory, as a step towards
+understanding the combustion of methane on these materials. For Pd-Pt alloys,
+models of surface oxide structures are built on the basis of known oxides on Pd
+and Pt. The methane adsorption energy presents large variations depending on
+the oxide structure and composition. Adsorption is endothermic on the bare
+Pd(111) metal surface as well as on stable thin layer oxide structures such as
+the ($\sqrt{5}\times\sqrt{5}$) surface oxide on Pd(100) and the PtO$_2$-like
+oxide on Pt(111). Instead, large adsorption energies are obtained for the (100)
+surface of bulk PdO, for metastable mixed Pd$_{1-x}$Pt$_x$O$_{4/3}$ oxide
+layers on Pt(100), and for Pd-Pt(111) surfaces covered with one oxygen
+monolayer. In the latter case, we find a net thermodynamic preference for a
+direct conversion of methane to methanol, which remains adsorbed on the
+oxidized metal substrates via weak hydrogen-bond interactions.",1003.4114v1
+2011-06-03,Simple self-gettering differential-pump for minimizing source oxidation in oxide-MBE environment,"Source oxidation of easily oxidizing elements such as Ca, Sr, Ba, and Ti in
+an oxidizing ambient leads to their flux instability and is one of the biggest
+problems in the multi-elemental oxide Molecular Beam Epitaxy technique. Here we
+report a new scheme that can completely eliminate the source oxidation problem:
+a self-gettering differential pump using the source itself as the pumping
+medium. The pump simply comprises a long collimator mounted in front of the
+source in extended port geometry. With this arrangement, the oxygen partial
+pressure near the source was easily maintained well below the source oxidation
+regime, resulting in a stabilized flux, comparable to that of an
+ultra-high-vacuum environment. Moreover, this pump has a self-feedback
+mechanism that allows a stronger pumping effectiveness for more easily
+oxidizing elements, which is a desired property for eliminating the source
+oxidation problem.",1106.0677v1
+2013-01-08,Shot-Peening of Pre-Oxidized Plates of Zirconium: Influence of Residual Stress on Oxidation,"The present study deals with oxidation behavior under residual stress of
+shot-peened plates of ""commercially pure"" zirconium exposed for 30 min at 650
+C. The influence of the shot-peening on a pre-oxidized material is presented.
+The results have been used to determine the influences of these chemical
+(preoxidation) and mechanical (shot-peening) treatments on the high temperature
+oxidation of zirconium. The oxygen profile was revealed using micro-hardness
+techniques and confirmed by SEM-EDS techniques. After pre-oxidation the samples
+were first resurfaced then shot-peened in order to introduce residual stress. A
+significant increase of the hardness of about 400 HV was observed on
+pre-oxidized shot-peened samples. Thermogravimetric analysis for 30 min at 650
+C under 200 mbar O2 showed a significantly slower oxidation rate for
+shot-peened samples. A comparison with our computations points out the role of
+the residual stresses on the diffusion and, consequently, on the oxidation.",1301.1635v2
+2019-09-30,"The effect of surface preparation on high temperature oxidation of Ni, Cu and Ni-Cu alloy","In the present paper, the analysis of polishing, grinding and sand-blasting
+processes on oxidation behavior of nickel, copper and nickel-copper alloy has
+been investigated. Surface roughness has been measured using two methods: by
+contact profilometer and by fractal analysis. It has been proved that
+sand-blasting process influences the surface roughness the most but also
+contaminates the surface with alumina particles. The oxidation tests were
+performed in thermogravimetrical furnace. The obtained mass gain plots, SEM
+microphotographs of cross-sections and SEM EDS analysis of the samples prove
+that surface preparation changes oxidation kinetics morphology of the polished
+and ground samples does not vary significantly after oxidation at investigated
+temperatures, but differences in oxide layer thicknesses and mass gains were
+observed. Oxidized sandblasted samples reveal that increased surface roughness
+and alumina intrusions change the oxidation process mixed Al (Ni, Cu or Ni-Cu)
+oxide is formed and separate Al2O3 particles are visible. The results prove
+that surface preparation influence high temperature oxidation of the samples by
+promoting new diffusion mechanism.",1909.13659v2
+2021-05-24,Manganese oxide coated TiO2 nanotube-based electrode for efficient and selective electrocatalytic sulfide oxidation to colloidal sulfur,"Manganese oxide-coated TiO2 nanotube array (NTA) was synthesized and applied
+for the (electro)catalytic oxidation of sulfide. By setting the
+electrodeposition parameters and calcination temperature, the coating obtained
+was MnO2 or Mn2O3, with rod or needle like morphology. Excellent catalytic
+activity of the Ti/TiO2 NTA/MnxOy anodes resulted in robust and selective
+oxidation of sulfide to elemental sulfur via an inner sphere complex between
+the sulfide ion and Mn-oxide. The penetration of the MnxOy inside the NTA
+improved adhesion and enhanced the electron transfer, thus enabling complete
+and rapid electrocatalytic re-oxidation of the Mn-oxide coating. At pH 8, the
+final product of sulfide oxidation was colloidal sulfur, S8, which prevented
+anode passivation and enabled a stable (electro)catalytic activity in the
+subsequent applications. This was observed in both synthetic electrolyte and
+real sewage, thus demonstrating the efficiency of the Ti/TiO2 NTA/MnxOy anode
+for sulfide oxidation in complex waste streams.",2105.11191v1
+2023-11-26,On the special oxidation mechanism of a Mg-Y-Al alloy contained LPSO phase at high temperatures,"This work investigated the oxidation of Mg-11Y-1Al alloy in Ar-20%O2 at
+500{\deg}through multiscale characterization. The results show that the
+network-like long-period stacking ordered(LPSO) phase decomposed into a
+needle-like LPSO phase and a polygonal Mg24Y5 phase. The needle-like LPSO phase
+resulted in the formation of a high-dense of needle-like oxide at the oxidation
+front of the area initially occupied by the network-like LPSO phase. The
+further inward oxygen would diffuse along the needle-like oxide-matrix
+interfaces and react with Y in the surrounding Mg matrix, resulting in the
+lateral growth of these needle-like oxides. Finally, the discrete needle-like
+oxides were interconnected to form a thicker and continuous oxide scale which
+could be more effective in hindering the elemental diffusion. Meanwhile, Al
+could partially enter the Y2O3 oxide scale and formed a strengthened (Y,Al)O
+oxide scale which could show a greater resistance to cracking and debonding.",2311.15182v1
+2014-11-28,Growth control of the oxidation state in vanadium oxide thin films,"Precise control of the chemical valence or oxidation state of vanadium in
+vanadium oxide thin films is highly desirable for not only fundamental
+research, but also technological applications that utilize the subtle change in
+the physical properties originating from the metal- insulator transition (MIT)
+near room temperature. However, due to the multivalent nature of vanadium and
+the lack of a good understanding on growth control of the oxidation state,
+stabilization of phase pure vanadium oxides with a single oxidation state is
+extremely challenging. Here, we systematically varied the growth conditions to
+clearly map out the growth window for preparing phase pure epitaxial vanadium
+oxides by pulsed laser deposition for providing a guideline to grow high
+quality thin films with well-defined oxidation states of V2(+3)O3, V(+4)O2, and
+V2(+5)O5. A well pronounced MIT was only observed in VO2 films grown in a very
+narrow range of oxygen partial pressure P(O2). The films grown either in lower
+(< 10 mTorr) or higher P(O2) (> 25 mTorr) result in V2O3 and V2O5 phases,
+respectively, thereby suppressing the MIT for both cases. We have also found
+that the resistivity ratio before and after the MIT of VO2 thin films can be
+further enhanced by one order of magnitude when the films are further oxidized
+by post-annealing at a well-controlled oxidizing ambient. This result indicates
+that stabilizing vanadium into a single valence state has to compromise with
+insufficient oxidation of an as grown thin film and, thereby, a subsequent
+oxidation is required for an improved MIT behavior.",1411.7922v1
+2020-06-19,High-Temperature Oxidation Kinetics of Additively Manufactured NiTiHf,"NiTi-based high-temperature shape memory alloys (HTSMAs) such as NiTiHf have
+been utilized in a broad range of applications due to their high strength and
+work output, as well as, their ability to increase the transformation
+temperatures (TTs). Recently, additive manufacturing techniques (AM) have been
+widely used to fabricate complex shape memory alloy components without any
+major modifications or tooling and has paved the way to tailor the
+manufacturing and fabrications of microstructure and critical properties of
+their final parts. NiTi alloys properties such as transformation temperatures
+can be significantly altered due to oxidation, which can occur during the
+manufacturing process or post-processing. In this work, the oxidation behavior
+of Ni-rich NiTi20Hf shape memory alloys, which was fabricated by the selective
+laser melting (SLM) method, is evaluated. Thermogravimetric analysis (TGA) is
+used to assess the kinetic behavior of the oxidation at different temperature
+ranges of 500, 700, and 900 C for 20 hours in the air. After oxidation, to
+evaluate the microstructure and chemical composition X-ray diffraction (XRD),
+scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy
+(EDS) was conducted. The isothermal oxidation kinetics of conventional NiTi20Hf
+alloys were studied, and the results were compared to AM samples. Results show
+a two-stage oxidation rate at which oxidation increased with the high rate at
+the initial stage. As the oxidation time increased, the oxidation rate
+gradually decreased. The oxidation behavior of NiTiHf alloys initially obeyed
+logarithmic rate law and then followed by parabolic rate law. SEM results
+showed the formation of a multi-layered oxide scale, including TiO2, NiTiO3,
+and Hf oxide.",2006.11114v1
+2021-07-03,Effect of Vanadium Thickness and Deposition Temperature on VO2 Synthesis using Atmospheric Pressure Thermal Oxidation,"Vanadium dioxide (VO2) is a phase transition material that undergoes a
+reversible insulator-metal phase transition at ~ 68 C. Atmospheric pressure
+thermal oxidation (APTO) of vanadium (V) is a simple VO2 synthesis method in
+which V thin film is oxidized in open air. For an optimum oxidation duration,
+VO2 films are obtained with good phase transition properties. We recently
+reported a modified APTO process using a step temperature profile for oxidation
+(Thin Solid Films 706, 138003 (2020)). We demonstrated an ultra-low thermal
+budget synthesis of VO2 thin films with good electrical and optical phase
+transition properties. For a 130 nm room-temperature RF sputtered V thin film,
+an optimum oxidation duration of ~ 30 s was obtained. In this work, we study
+how the starting V film thickness and deposition temperature affects the
+optimum oxidation duration. V thin films of varying thickness (15-212 nm) and
+120 nm thick V films with varying deposition temperature (~27-450 C) are
+prepared using RF magnetron sputtering. These films are oxidized for different
+oxidation durations and characterized using Raman and four-probe measurements
+to find the optimum oxidation duration for each deposition condition. We find
+that the optimum oxidation duration increases with the increase in V film
+thickness and V deposition temperature. We model the effect of V film thickness
+and deposition temperature on the optimal oxidation time using a parabolic law
+which can be used to obtain the optimal oxidation times for intermediate V
+thicknesses/deposition temperatures.",2107.01413v1
+2022-11-30,Kinetic control for planar oxidation of MoS$_2$,"Layered transition metal dichalcogenide (TMD) semiconductors oxidize readily
+in a variety of conditions, and a thorough understanding of this oxide
+formation is required for the advancement of TMD-based microelectronics. Here,
+we combine scanning transmission electron microscopy (STEM) with spectroscopic
+ellipsometry (SE) to investigate oxide formation at the atomic scale of the
+most widely-studied TMD, MoS$_2$. We find that aggressive thermal oxidation
+results in $\alpha$-phase plate-like crystalline MoO$_3$ with sharp interfaces,
+voids, and a textured alignment with the underlying MoS$_2$. Experiments with
+remote substrates and patterned MoS$_2$ prove that thermal oxidation proceeds
+via vapor-phase mass transport and redeposition - a challenge to forming thin,
+conformal planar oxide films. We accelerate the kinetics of oxidation relative
+to the kinetics of mass transport using a non-thermal oxygen plasma process, to
+form a smooth and conformal amorphous oxide. The resulting amorphous MoO$_3$
+films can be grown several nanometers thick, and we calibrate the oxidation
+rate for varying plasma processing conditions. Our results illustrate how TMD
+semiconductor oxidation differs significantly from oxidation of legacy
+semiconductors, most notably silicon, and provide quantitative guidance for
+managing both the atomic scale structure and thin film morphology of oxides in
+the design and processing of MoS$_2$ semiconductor devices.",2211.16789v1
+2000-04-12,Resonant Spin-Dependent Tunneling in Spin-Valve Junctions in the Presence of Paramagnetic Impurities,"The tunnel magnetoresistance (TMR) of F/O/F magnetic junctions, (F's are
+ferromagnetic layers and O is an oxide spacer) in the presence of magnetic
+impurities within the barrier, is investigated. We assume that magnetic
+couplings exist both between the spin of impurity and the bulk magnetization of
+the neighboring magnetic electrode, and between the spin of impurity and the
+spin of tunneling electron. Consequently, the resonance levels of the system
+formed by a tunneling electron and a paramagnetic impurity with spin S=1, are a
+sextet. As a result the resonant tunneling depends on the direction of the
+tunneling electron spin. At low temperatures and zero bias voltage the TMR of
+the considered system may be larger than TMR of the same structure without
+paramagnetic impurities. It is calculated that an increase in temperature leads
+to a decrease in the TMR amplitude due to excitation of spin-flip processes
+resulting in mixing of spin up and down channels. It is also shown that
+asymmetry in the location of the impurities within the barrier can lead to
+asymmetry in $I(V)$ characteristics of impurity assisted current and two
+mechanisms responsible for the origin of this effect are established. The first
+one is due to the excitation of spin-flip processes at low voltages and the
+second one arises from the shift of resonant levels inside the insulator layer
+under high applied voltages.",0004198v2
+2002-08-09,Persistent magnetoresistive memory in phase separated manganites,"We have studied magnetic and transport properties on different manganese
+oxide based compounds exhibiting phase separation: polycrystalline
+La5/8-yPryCa3/8MnO3 (y=0.3) and La1/2Ca1/2Mn1-zFezO3 (z = 0.05), and single
+crystals of La5/8-yPryCa3/8MnO3 (y=0.35). Time dependent effects indicate that
+the fractions of the coexisting phases are dynamically changing in a definite
+temperature range. We found that in this range the ferromagnetic fraction f can
+be easily tuned by application of low magnetic fields (< 1 T). The effect is
+persistent after the field is turned off, thus the field remains imprinted in
+the actual value of f and can be recovered through transport measurements. This
+effect is due both to the existence of a true phase separated equilibrium state
+with definite equilibrium fraction f0, and to the slow growth dynamics. The
+fact that the same global features were found on different compounds and in
+polycrystalline and single crystalline samples, suggests that the effect is a
+general feature of some phase separated media.",0208199v1
+2003-02-21,"Transport and Magnetic Properties of R1-xAxCoO3 (R=La, Pr and Nd; A=Ba, Sr and Ca)","Transport and magnetic measurements have been carried out on perovskite
+Co-oxides R1-xAxCoO3 (R=La, Pr, and Nd; A=Ba, Sr and Ca; 0<x<0.5: All sets of
+the R and A species except Nd1-xBaxCoO3 have been studied.). With increasing
+the Sr- or Ba-concentration x, the system becomes metallic ferromagnet with
+rather large magnetic moments. For R=Pr and Nd and A=Ca, the system approaches
+the metal- insulator phase boundary but does not become metallic. The magnetic
+moments of the Ca-doped systems measured with the magnetic field H=0.1 T are
+much smaller than those of the Ba- and Sr-doped systems. The thermoelectric
+powers of the Ba- and Sr-doped systems decrease from large positive values of
+lightly doped samples to negative ones with increasing doping level, while
+those of Ca-doped systems remain positive. These results can be understood by
+considering the relationship between the average ionic radius of R1-xAx and the
+energy difference between the low spin and intermediate spin states. We have
+found the resistivity-anomaly in the measurements of Pr1-xCaxCoO3 under
+pressure in the wide region of x, which indicates the existence of a phase
+transition different from the one reported in the very restricted region of
+x~0.5 at ambient pressure [Tsubouchi et al. Phys. Rev. B 66 (2002) 052418.]. No
+indication of this kind of transition has been observed in other species of R.",0302435v1
+2005-09-12,Pressure dependence of magnetic and superconducting transitions in sodium cobalt oxides NaxCoO2,"The results of DC magnetization measurements under hydrostatic (helium-gas)
+pressure are reported for an ambient pressure superconductor Na0.35CoO2.1.4D2O
+and its precursor compound, the gamma-phase Na0.75CoO2 that is known to combine
+a metallic conductivity with an unusual magnetic state below ~22K. The obtained
+data allowed us to present for the first time the pressure dependence of the
+magnetic transition in a metallic sodium cobaltate system. This dependence
+appears to be positive, with the magnetic transition rapidly shifting towards
+higher temperatures when an applied pressure increases. We ascribe the observed
+effect to the pressure-induced enhancement of the out-of-plane
+antiferromagnetic coupling mediated by localized spins interactions (of either
+superexchange or RKKY type), the scenario consistent with the A-type
+antiferromagnetic state suggested by recent neutron-scattering data. As for the
+pressure effect on the superconductivity in Na0.35CoO2.1.4D2O, our measurements
+established negative and linear for the entire pressure range from 1 bar to 8.3
+kbar pressure dependence of Tc, the behavior quite different from the reported
+by previous workers strong non-linearity of the Tc (P) dependence. (Dated
+September 12, 2005)
+  PACS numbers: 74.62.Fj, 74.70.-b, 75.20. En, 75.50 Ee, 75.30 Kz.",0509308v1
+2010-04-28,"Synthesis, Structure and Properties of Tetragonal Sr2M3As2O2 (M3 = Mn3, Mn2Cu and MnZn2) Compounds Containing Alternating CuO2-Type and FeAs-Type Layers","Polycrystalline samples of Sr2Mn2CuAs2O2, Sr2Mn3As2O2, and Sr2Zn2MnAs2O2 were
+synthesized. Their temperature- and applied magnetic field-dependent
+structural, transport, thermal, and magnetic properties were characterized by
+means of x-ray and neutron diffraction, electrical resistivity rho, heat
+capacity, magnetization and magnetic susceptibility measurements. These
+compounds have a body-centered-tetragonal crystal structure (space group
+I4/mmm) that consists of MO2 (M = Zn and/or Mn) oxide layers similar to the
+CuO2 layers in high superconducting transition temperature Tc cuprate
+superconductors, and intermetallic MAs (M = Cu and/or Mn) layers similar to the
+FeAs layers in high-Tc pnictides. These two types of layers alternate along the
+crystallographic c-axis and are separated by Sr atoms. The site occupancies of
+Mn, Cu and Zn were studied using Rietveld refinements of x-ray and neutron
+powder diffraction data. The temperature dependences of rho suggest metallic
+character for Sr2Mn2CuAs2O2 and semiconducting character for Sr2Mn3As2O2 and
+Sr2Zn2MnAs2O2. Sr2Mn2CuAs2O2 is inferred to be a ferrimagnet with a Curie
+temperature TC = 95(1) K. Remarkably, we find that the magnetic ground state
+structure changes from a G-type antiferromagnetic structure in Sr2Mn3As2O2 to
+an A-type ferrimagnetic structure in Sr2Mn2CuAs2O2 in which the Mn ions in each
+layer are ferromagnetically aligned, but are antiferromagnetically aligned
+between layers.",1004.5038v1
+2011-07-27,Magnetic frustration in the context of pseudo-dipolar ionic disorder,"We consider an alternative to the usual spin glass paradigm for disordered
+magnetism, consisting of the previously unstudied combination of frustrated
+magnetic interactions and pseudo-dipolar disorder in spin positions. We argue
+that this model represents a general limiting case for real systems as well as
+a realistic model for certain binary fluorides and oxides. Furthermore, it is
+of great relevance to the highly topical subjects of the Coulomb phase and
+`charge ice'. We derive an analytical solution for the ground state phase
+diagram of a model system constructed in this paradigm and identify magnetic
+phases that remain either disordered or partially ordered even at zero
+temperature. These phases are of a hitherto unobserved type, but may be broadly
+classified as either `spin liquids' or `semi-spin liquids' in contrast to the
+usual spin glass or semi-spin glass. Numerical simulations are used to show
+that the spin liquid phase exhibits no spin glass transition at finite
+temperature, despite the combination of frustration and disorder. By mapping
+onto a model of uncoupled loops of Ising spins, we show that the magnetic
+structure factor of this phase acts, in the limit $T\rightarrow0$, as a
+sensitive probe of the positional disorder correlations. We suggest that this
+result can be generalized to more complex systems, including experimental
+realizations of canonical spin glass models.",1107.5411v2
+2011-08-16,Direct imaging of the coexistence of ferromagnetism and superconductivity at the LaAlO3/SrTiO3 interface,"LaAlO3 and SrTiO3 are insulating, nonmagnetic oxides, yet the interface
+between them exhibits a two-dimensional electron system with high electron
+mobility,1 superconductivity at low temperatures,2-6 and electric-field-tuned
+metal-insulator and superconductorinsulator phase transitions.3,6-8 Bulk
+magnetization and magnetoresistance measurements also suggest some form of
+magnetism depending on preparation conditions5,9-11 and suggest a tendency
+towards nanoscale electronic phase separation.10 Here we use local imaging of
+the magnetization and magnetic susceptibility to directly observe a landscape
+of ferromagnetism, paramagnetism, and superconductivity. We find submicron
+patches of ferromagnetism in a uniform background of paramagnetism, with a
+nonuniform, weak diamagnetic superconducting susceptibility at low temperature.
+These results demonstrate the existence of nanoscale phase separation as
+suggested by theoretical predictions based on nearly degenerate interface
+sub-bands associated with the Ti orbitals.12,13 The magnitude and temperature
+dependence of the paramagnetic response suggests that the vast majority of the
+electrons at the interface are localized, and do not contribute to transport
+measurements.3,6,7 In addition to the implications for magnetism, the existence
+of a 2D superconductor at an interface with highly broken inversion symmetry
+and a ferromagnetic landscape in the background suggests the potential for
+exotic superconducting phenomena.",1108.3150v1
+2012-06-25,Interplay between spin-orbit coupling and Hubbard interaction in SrIrO3 and related Pbnm perovskites,"There has been a rapidly growing interest on the interplay between spin-orbit
+coupling (SOC) and Hubbard interaction U in correlated materials. A current
+consensus is that the stronger the SOC, the smaller is the critical interaction
+Uc required for a spin-orbit Mott insulator, because the atomic SOC splits a
+band into different total angular momentum bands narrowing the effective
+bandwidth. It was further claimed that at large enough SOC, the stronger the
+SOC, the weaker the Uc because in general the effective SOC is enhanced with
+increasing electron-electron interaction strength. Contrary to this
+expectation, we find that, in orthorhombic perovskite oxides (Pbnm), the
+stronger the SOC, the bigger the Uc. This is originated from a line of Dirac
+node in Jeff=1/2 bands near the Fermi level inherited from a combination of the
+lattice structure and a large SOC. Due to this protected line of nodes, there
+are small hole and electron pockets in SrIrO3, and such a small density of
+states makes Hubbard interaction less efficient in building a magnetic
+insulator. The full phase diagram in U vs. SOC is obtained, where non-magnetic
+semimetal, magnetic metal, and magnetic insulator are found. Magnetic ordering
+patterns beyond Uc are also presented. We further discuss implications of our
+finding in relation to other perovskites such as SrRhO3 and SrRuO3.",1206.5836v2
+2013-04-01,Spin and Dipole Ordering in Ni_2InSbO_6 and Ni_2ScSbO_6 with corundum-related structure,"The complex metal oxides Ni2InSbO6 (NISO) and Ni2ScSbO6 (NSSO) have been
+prepared in form of polycrystalline powders by a solid state reaction route.
+The crystal structure and magnetic properties of the compounds were
+investigated using a combination of X-ray and neutron powder diffraction,
+electron microscopy, calorimetric and magnetic measurements. The compounds
+adopt a trigonal structure, space group R3, of the corundum related Ni3TeO6
+(NTO) type. Only one of the octahedral Ni positions (Ni(2)) of the NTO
+structure was found to be occupied by In (Sc). NTO has non-centrosymmetric
+structure and is ferroelectric below 1000 K, dielectric and second harmonic
+measurements suggest that also NISO and NSSO are correspondingly ferroelectric.
+Magnetization measurements signified antiferromagnetic ordering below TN=60 K
+(NSSO) and 76 K (NISO). The magnetic structure is formed by two
+antiferromagnetically coupled incommensurate helices with the spiral axis along
+the b-axis and propagation vector k = [0, ky,0] with ky= 0.036(1) (NSSO) and
+ky= 0.029(1) (NISO). The observed structural and magnetic properties of NISO
+and NSSO are discussed and compared with those of NTO.",1304.0474v1
+2013-04-17,Magnetism and electronic structure of La2ZnIrO6 and La2MgIrO6: candidate Jeff =1/2 Mott insulators,"We study experimentally and theoretically the electronic and magnetic
+properties of two insulating double perovskites that show similar atomic and
+electronic structure, but different magnetic properties. In magnetization
+measurements, La2ZnIrO6 displays weak ferromagnetic behavior below 7.5 K
+whereas La2MgIrO6 shows antiferromagnetic behavior (AFM) below TN = 12 K.
+Electronic structure calculations find that the weak ferromagnetic behavior
+observed in La2ZnIrO6 is in fact due to canted antiferromagnetism. The
+calculations also predict canted antiferromagnetic behavior in La2MgIrO6, but
+intriguingly this was not observed. Neutron diffraction measurements confirm
+the essentially antiferromagnetic behavior of both systems, but lack the
+sensitivity to resolve the small (0.22 {\mu}B/Ir) ferromagnetic component in
+La2ZnIrO6. Overall, the results presented here indicate the crucial role of
+spin-orbit coupling (SOC) and the on-site Coulomb repulsion on the magnetic,
+transport, and thermodynamic properties of both compounds. The electronic
+structure calculations show that both compounds, like Sr2IrO4, are Jeff = 1/2
+Mott insulators. Our present findings suggest that La2ZnIrO6 and La2MgIrO6
+provide a new playground to study the interplay between SOC and on-site Coulomb
+repulsion in a 5d transition metal oxide.",1304.4769v1
+2014-01-09,FMR Study of Co/Ti Bilayer Thin Films,". We focused on the interaction between two ferromagnetic cobalt layers
+through a non-magnetic titanium layer. The magnetic properties of the structure
+were characterized by ferromagnetic resonance technique (FMR). The data were
+collected as a function of non-magnetic titanium layer thickness. Co/Ti
+multilayer (Ti (50 {\AA})/Co(45 {\AA})/Ti(2-40 {\AA})/Co(40 {\AA})/Ti(100
+{\AA}))films were grown onto naturally oxidized p-type single crystal Si (100)
+substrate at UHV condition with magnetron sputtering system at room
+temperature. The thickness of Ti spacer layer ranges from 2 to 40 {\AA} with 2
+{\AA} steps. We did not observe usual optic and acoustic modes; instead we had
+two broad overlapped peaks for the films ranged from 6 {\AA} to 40 {\AA}. One
+interesting result was the high anisotropic resonance field values for these
+films. Exchange coupling between ferromagnetic layers causes shift on resonance
+field values but these shifts in our samples were much larger than expected.
+This large anisotropic behavior is not clear at the moment. Our theoretical
+model was not able to determine a value for the exchange coupling parameter.
+One reason can be the close thickness values for Co sublayers. The other reason
+can be the Ti non-magnetic layer. If titanium did not grow layer by layer on
+cobalt, the cobalt ferromagnetic layers may behave as a single layer. As a
+result one cannot observe exchange interaction between ferromagnetic layers
+through non-magnetic spacer.",1401.1924v1
+2014-02-05,Size and shape control of magnetite nanoparticles with a nonselective binding surfactants,"A Martian meteorite, magnetic inks, drug targeting, batteries, contrasts for
+MRI, data storage or even clinical thermo-therapy seem to have no connection,
+but all have in common a dark mineral called magnetite. However, in each of
+these applications this iron oxide shows up with different forms because their
+optical, electrical and magnetic properties are strongly dependent on size,
+shape and kind of surfactant. In this sense the control of this characteristics
+has long been of scientific and technological interest. In an AC magnetic
+field-assisted cancer therapy, \textit{e.g.}, from a biological point of view,
+the interaction of the nanoparticles with cells is critically determined by the
+surface properties which control their fate in biological environments. Besides
+the size, factors as the shape also seems to affect the cellular uptake. On the
+other hand, the specific absorption rate (SAR) at a fixed frequency and
+magnetic field, is hugely dependent on average and distribution of size, shape,
+crystalline anisotropy, and degree of aggregation or agglomeration of the
+nanoparticles. Each of these factors contributes to an independent energy loss
+mechanism: N\'eel relaxation, Brown relaxation or magnetic hysteresis loss.
+Thus, the key for improving the efficiency of a given application is the
+knowledge about the morphological control.",1402.1134v1
+2014-09-29,Unconventional magnetism in the layered oxide LaSrRhO$_4$,"We have prepared polycrystalline samples of LaSrRh$_{1-x}$Ga$_x$O$_4$ and
+LaSr$_{1-x}$Ca$_x$RhO$_4$,and have measured the x-ray diffraction, resistivity,
+Seebeck coefficient, magnetization and electron spin resonance in order to
+evaluate their electronic states. The energy gap evaluated from the resistivity
+and the Seebeck coefficient systematically changes with the Ga concentration,
+and suggests that the system changes from a small polaron insulator to a band
+insulator. We find that all the samples show Curie-Weiss-like susceptibility
+with a small Weiss temperature of the order of 1 K, which is seriously
+incompatible with the collective wisdom that a trivalent rhodium ion is
+nonmagnetic. We have determined the $g$ factor to be $g$=2.3 from the electron
+spin resonance, and the spin number to be $S$=1 from the magnetization-field
+curves by fitting with a modified Brillouin function. The fraction of the $S$=1
+spins is 2--5%, which depends on the degree of disorder in the La/Sr/Ca-site,
+which implies that disorder near the apical oxygen is related to the magnetism
+of this system. A possible origin for the magnetic Rh$^{3+}$ ions is discussed.",1409.8092v1
+2014-11-03,Sign problem free quantum Monte-Carlo study on thermodynamic properties and magnetic phase transitions in orbital-active itinerant ferromagnets,"The microscopic mechanism of itinerant ferromagnetism is a long-standing
+problem due to the lack of non-perturbative methods to handle strong magnetic
+fluctuations of itinerant electrons. We have non-pertubatively studied
+thermodynamic properties and magnetic phase transitions of a two-dimensional
+multi-orbital Hubbard model exhibiting ferromagnetic ground states. Quantum
+Monte-Carlo simulations are employed, which are proved in a wide density region
+free of the sign problem usually suffered by simulations for fermions. Both
+Hund's coupling and electron itinerancy are essential for establishing the
+ferromagnetic coherence. No local magnetic moments exist in the system as a
+priori, nevertheless, the spin channel remains incoherent showing the
+Curie-Weiss type spin magnetic susceptibility down to very low temperatures at
+which the charge channel is already coherent exhibiting a weakly
+temperature-dependent compressibility. For the SU(2) invariant systems, the
+spin susceptibility further grows exponentially as approaching zero temperature
+in two dimensions. In the paramagnetic phase close to the Curie temperature,
+the momentum space Fermi distributions exhibit strong resemblance to those in
+the fully polarized state. The long-range ferromagnetic ordering appears when
+the symmetry is reduced to the Ising class, and the Curie temperature is
+accurately determined. These simulations provide helpful guidance to searching
+for novel ferromagnetic materials in both strongly correlated $d$-orbital
+transition metal oxide layers and the $p$-orbital ultra-cold atom optical
+lattice systems.",1411.0340v2
+2014-12-12,Magnetoresistance from broken spin helicity,"The propensity of some materials and multilayers to have a magnetic field
+dependent resistance, called magnetoresistance, has found commercial
+applications such as giant magnetoresistance harddisk read heads. But
+magnetoresistance can also be a powerful probe of electronic and magnetic
+interactions in matter. For example, magnetoresistance can be used to analyze
+multiband conductivity, conduction inhomogeneity, localized magnetic moments,
+and (fractional) Landau level structure. For materials with strong spin-orbit
+interaction, magnetoresistance can be used as a probe for weak antilocalization
+or a nontrivial Berry phase, such as in topological insulator surface states.
+For the three dimensional topological insulators a large and linear
+magnetoresistance is often used as indication for underlying non-trivial
+topology, although the origin of this effect has not yet been established.
+Here, we observe a large magnetoresistance in the conducting bulk state of
+Bi$_2$Te$_3$. We show that this type of large magnetoresistance is due to the
+competition between helical spin-momentum locking (i.e. spin rotates with
+momentum direction) and the unidirectional spin alignment by an applied
+magnetic field. Warping effects are found to provide the (quasi) linear
+dependence on magnetic field. We provide a quantitative model for the helicity
+breaking induced magnetoresistance that can be applied to a vast range of
+materials, surfaces or interfaces with weak to strong spin-orbit interactions,
+such as the contemporary oxide interfaces, bulk Rashba systems, and topological
+insulator surface states.",1412.4065v1
+2015-07-15,Structural anomalies and short-range magnetic correlations in the orbitally degenerated system Sr$_2$VO$_4$,"We report on the electronic ground state of a layered perovskite vanadium
+oxide Sr$_2$VO$_4$ studied by the combined use of synchrotron radiation x-ray
+diffraction (SR-XRD) and muon spin rotation/relaxation ($\mu$SR) techniques,
+where $\mu$SR measurements were extended down to 30 mK. We found an
+intermediate orthorhombic phase between $T_{\rm c2} \sim$~130 K and $T_{\rm c1}
+\sim$~100 K, whereas a tetragonal phase appears for $T > T_{\rm c2}$ and $T <
+T_{\rm c1}$. The absence of long-range magnetic order was confirmed by $\mu$SR
+at the reentrant tetragonal phase below $T_{\rm c1}$, where the relative
+enhancement in the $c$-axis length versus that of the $a$-axis length was
+observed. However, no clear indication of the lowering of the tetragonal
+lattice symmetry with superlattice modulation, which is expected in the orbital
+order state with superstructure of $d_{yz}$ and $d_{zx}$ orbitals, was observed
+by SR-XRD below $T_{\rm c1}$. Instead, it was inferred from $\mu$SR that a
+magnetic state developed below $T_{\rm c0} \sim$~10 K, which was characterized
+by the highly inhomogeneous and fluctuating local magnetic fields down to 30
+mK. We argue that the anomalous magnetic ground state below $T_{\rm c0}$
+originates from the coexistence of ferromagnetic and antiferromagnetic
+correlations.",1507.04139v1
+2016-07-21,Possibility of an unconventional spin state of Ir$^{4+}$ in Ba$_{21}$Ir$_9$O$_{43}$ single crystal,"We report the synthesis of single crystals of a novel layered iridate
+Ba$_{21}$Ir$_9$O$_{43}$, and present the crystallographic, transport and
+magnetic properties of this material. The compound has a hexagonal structure
+with two iridium oxide layers stacked along the $c$ direction. One layer
+consists of a triangular arrangement of Ir$_2$O$_9$ dimers while the other
+layer comprises two regular octahedra and one triangular pyramid, forming
+inter-penetrated triangular lattices. The resistivity as a function of
+temperature exhibits an insulating behavior, with a peculiar $T^{-3}$ behavior.
+Magnetic susceptibility shows antiferromagnetic Curie-Weiss behavior with
+$\Theta_\mathrm{CW} \simeq -$90 K while a magnetic transition occurs at
+substantially lower temperature of 9 K. We discuss possible valence states and
+effective magnetic moments on Ir ions in different local environments, and
+argue that the Ir ions in a unique triangular-pyramidal configuration likely
+carry unusually large magnetic moments.",1607.06441v2
+2018-11-19,Room-temperature Low-field Colossal Magneto-resistance in Double-perovskite Manganite,"The gigantic decrease of resistance by an applied magnetic field, which is
+often referred to as colossal magnetoresistance (CMR), has been an attracting
+phenomenon in strongly correlated electron systems. The discovery of CMR in
+manganese oxide compounds has developed the science of strong coupling among
+charge, orbital, and spin degrees of freedom. CMR is also attracting scientists
+from the viewpoint of possible applications to sensors, memories, and so on.
+However, no application using CMR effect has been achieved so far, partly
+because the CMR materials which satisfy all of the required conditions for the
+application, namely, high operating temperature, low operating magnetic field,
+and sharp resistive change, have not been discovered. Here we report a
+resistance change of more than two-orders of magnitude at a magnetic field
+lower than 2 T near 300 K in an A-site ordered NdBaMn_2_O_6_ crystal. When
+temperature and a magnetic field sweep from insulating (metallic) phase to
+metallic (insulating) phase, the insulating (metallic) conduction changes to
+the metallic (insulating) conduction within 1 K and 0.5 T, respectively. The
+CMR is ascribed to the melting of the charge ordering. The entropy change which
+is estimated from the B-T phase diagram is smaller than what is expected for
+the charge and orbital ordering. The suppression of the entropy change is
+attributable to the loss of the short range ferromagnetic fluctuation of Mn
+spin moments, which an important key of the high temperature and low magnetic
+field CMR effect.",1811.07596v1
+2018-11-29,Structural and Magnetic Study of Metallo-Organic YIG Powder Using 2-ethylhexanoate Carboxylate Based Precursors,"The crystallization and magnetic behavior of yttrium iron garnet (YIG)
+prepared by metallo-organic decomposition (MOD) method are discussed. The
+chemistry and physics related to synthesis of iron and yttrium carboxylates
+based on 2-ethylhexanoic acid (2EHA) are studied, since no literature was found
+which elucidates synthesis of metallo-organic precursor of YIG in spite of the
+literatures of doped YIG samples such as Bi-YIG. Typically, the metal
+carboxylates used in preparation of ceramic oxide materials are
+2-ethylhexanoate (2EH) solvents. Herein, the synthesis, thermal behavior and
+solubility of yttrium and iron 2EH used in synthesis of YIG powder by MOD are
+reported. The crystallization and magnetic parameters, including saturation
+magnetization and coercivity of these samples, smoothly change as a function of
+the annealing temperature. It is observed that high sintering temperature of
+1300 to 1400 {\deg}C promotes the diffraction peaks of YIG, therefore, we can
+conclude that the formation of YIG in MOD method increases the crystallization
+temperature. The maximum value of saturation magnetization and minimum value of
+coercivity and remanence are observed for the sample sintered at 1200{\deg}C
+which are 13.7 emu/g, 10.38 Oe and 1.5 emu/g, respectively. This study cites
+the drawbacks in chemical synthesis of metallo-organic based YIG production.",1811.12514v1
+2016-11-16,Switching based Spin Transfer Torque Oscillator with zero-bias field and large tuning-ratio,"We propose a novel concept of obtaining oscillations with frequencies in
+very-high frequency (VHF) and ultra-high frequency (UHF) bands. A traditional
+spin torque nano-oscillator (STNO) consists of at least one pinned layer (PL)
+and one free layer (FL) which precesses in a fixed orbit, defined by a
+precession angle, which results in magneto-resistance (MR) oscillations. In
+STNO, with aligned or even orthogonal easy-axis of the magnetic layers and with
+or without external bias magnetic field, it is not possible to attain full MR
+swing. The constringed MR swing jeopardizes the extracted output power.
+Furthermore, the orbit is strongly disturbed by the thermal fluctuations
+resulting in strong magnetic noise. In stark contrast to the operation
+principle of a STNO, we theoretically demonstrate, with the practical
+parameters from the experiments, that with a unidirectional current in a dual
+asymmetric free-layers (with no pinned layer) based perpendicular magnetic
+tunnel junction (pMTJ), both of the free layers can attain a complete and
+out-of-phase self-sustained switching without the aid of any external magnetic
+field. This design facilitates a switching based spin torque oscillator
+(SW-STO) with a full MR swing, and hence a larger output power, for stable and
+more thermally robust free-running oscillations. Furthermore, the integration
+with the n-type metal-oxide-semiconductor (NMOS) field-effect transistors at
+130, 65 and 14 nm node is appraised to expound its effect on the oscillator
+performance, controllability with DC bias and the design constraints, to
+demonstrate the viability of the design as a dynamically controllable
+oscillator for practical on-chip implementation.",1611.05169v3
+2017-01-16,High-field transport properties of a P-doped BaFe2As2 film on technical substrate,"High temperature (high-Tc) superconductors like cuprates have superior
+critical current properties in magnetic fields over other superconductors.
+However, superconducting wires for high-field-magnet applications are still
+dominated by low-Tc Nb3Sn due probably to cost and processing issues. The
+recent discovery of a second class of high-Tc materials, Fe-based
+superconductors, may provide another option for high-field-magnet wires. In
+particular, AEFe2As2 (AE: Alkali earth elements, AE-122) is one of the best
+candidates for high-field-magnet applications because of its high upper
+critical field, Hc2, moderate Hc2 anisotropy, and intermediate Tc. Here we
+report on in-field transport properties of P-doped BaFe2As2 (Ba-122) thin films
+grown on technical substrates (i.e., biaxially textured oxides templates on
+metal tapes) by pulsed laser deposition. The P-doped Ba-122 coated conductor
+sample exceeds a transport Jc of 10^5 A/cm^2 at 15 T for both major
+crystallographic directions of the applied magnetic field, which is favourable
+for practical applications. Our P-doped Ba-122 coated conductors show a
+superior in-field Jc over MgB2 and NbTi, and a comparable level to Nb3Sn above
+20 T. By analysing the E-J curves for determining Jc, a non-Ohmic linear
+differential signature is observed at low field due to flux flow along the
+grain boundaries. However, grain boundaries work as flux pinning centres as
+demonstrated by the pinning force analysis.",1701.04154v1
+2018-05-07,Electrically controlled long-distance spin transport through an antiferromagnetic insulator,"Spintronics uses spins, the intrinsic angular momentum of electrons, as an
+alternative for the electron charge. Its long-term goal is in the development
+of beyond-Moore low dissipation technology devices. Recent progress
+demonstrated the long-distance transport of spin signals across ferromagnetic
+insulators. Antiferromagnetically ordered materials are however the most common
+class of magnetic materials with several crucial advantages over ferromagnetic
+systems. In contrast to the latter, antiferromagnets exhibit no net magnetic
+moment, which renders them stable and impervious to external fields. In
+addition, they can be operated at THz frequencies. While fundamentally their
+properties bode well for spin transport, previous indirect observations
+indicate that spin transmission through antiferromagnets is limited to short
+distances of a few nanometers. Here we demonstrate the long-distance, over tens
+of micrometers, propagation of spin currents through hematite (\alpha-Fe2O3),
+the most common antiferromagnetic iron oxide, exploiting the spin Hall effect
+for spin injection. We control the spin current flow by the interfacial
+spin-bias and by tuning the antiferromagnetic resonance frequency with an
+external magnetic field. This simple antiferromagnetic insulator is shown to
+convey spin information parallel to the compensated moment (N\'eel order) over
+distances exceeding tens of micrometers. This newly-discovered mechanism
+transports spin as efficiently as the net magnetic moments in the best-suited
+complex ferromagnets. Our results pave the way to ultra-fast, low-power
+antiferromagnet-insulator-based spin-logic devices that operate at room
+temperature and in the absence of magnetic fields.",1805.02451v1
+2016-12-08,Elucidating the Voltage Controlled Magnetic Anisotropy,"Voltage controlled magnetic anisotropy (VCMA) is an efficient way to
+manipulate the magnetization states in nanomagnets, promising for low-power
+spintronic applications. The underlying physical mechanism for VCMA is known to
+involve a change in the d-orbital occupation on the transition metal interface
+atoms with an applied electric field. However, a simple qualitative picture of
+how this occupation controls the magnetocrystalline anisotropy (MCA) and even
+why in certain cases the MCA has opposite sign still remains elusive. In this
+paper, we exploit a simple model of orbital populations to elucidate a number
+of features typical for the interface MCA and the effect of electric field on
+it, for 3d transition metal thin films used in magnetic tunnel junctions. We
+find that in all considered cases including the Fe (001) surface, clean
+Fe1-xCox(001)/MgO interface and oxidized Fe(001)/MgO interface, the effects of
+alloying and electric field enhance the MCA energy with electron depletion
+which is largely explained by the occupancy of the minority-spin dxz,yz
+orbitals. On the other hand, the hole doped Fe(001) exhibits an inverse VCMA,
+where the MCA enhancement is achieved when electrons are accumulated at the Fe
+(001)/MgO interface with applied electric field. In this regime we predict a
+significantly enhanced VCMA which exceeds 1pJ/Vm. Realizing this regime
+experimentally may be favorable for a practical purpose of voltage driven
+magnetization reversal.",1612.02724v1
+2018-01-29,Observation of the Meissner effect at room temperature in single-layer graphene brought into contact with alkanes,"There are claims of synthesis of a room temperature superconductor. However,
+these claims have not been officially accepted by scientific communities.
+Currently, the highest transition temperature (Tc) recognized in scientific
+articles is 135 K at 1 atm of Hg-Ba-Ca-Cu-O system which is a copper oxide
+superconductor. We packed graphite flakes into a ring-shaped
+polytetrafluoroethylene (PTFE) tube and further injected heptane or octane.
+Then we generated circulating current in this ring tube by electromagnetic
+induction and showed that this circulating current continues to flow
+continuously at room temperature for 50 days. This experiment suggests that
+bringing alkane into contact with graphite may result in a material with zero
+resistance at room temperature. In addition, we showed by means of AC
+resistance measurements using the two-terminal method that the resistances of
+graphite fibers brought into contact with various alkanes suddenly change at
+specific critical temperatures between 363 and 504 K. In this study, we show
+that after a magnetic field is applied to a single-layer graphene at room
+temperature, alkane is brought into contact with the single-layer graphene,
+then the graphene excludes the magnetic field immediately. This phenomenon
+demonstrates that the alkane-wetted single-layer graphene shows Meissner effect
+at room temperature. Furthermore, we applied a magnetic field perpendicularly
+to the annular single-layer graphene brought into contact with n-hexane and
+immediately removed the magnetic field. After that we observed that a constant
+magnetic field generates from this annular graphene for some time. In
+conclusion, the single-layer graphene brought into contact with alkane shows
+Meissner effect at room temperature, which provides definitive evidence for
+room temperature superconductivity.",1801.09376v1
+2019-06-24,"Itinerancy-dependent non-collinear spin textures in SrFeO3, CaFeO3, and CaFeO3/SrFeO3 heterostructures probed via resonant x-ray scattering","Non-collinear, multi-q spin textures can give rise to exotic, topologically
+protected spin structures such as skyrmions, but the reason for their formation
+over simple single-q structures is not well understood. While lattice
+frustration and the Dzyaloshinskii-Moriya interaction are known to produce
+non-collinear spin textures, the role of electron itinerancy in multi-q
+formation is much less studied. Here we investigated the non-collinear, helical
+spin structures in epitaxial films of the perovskite oxides SrFeO3 and CaFeO3
+using magnetotransport and resonant soft x-ray magnetic diffraction. Metallic
+SrFeO3 exhibits features in its magnetoresistance that are consistent with its
+recently proposed multi-q structure. Additionally, the magnetic Bragg peak of
+SrFeO3 measured at the Fe L edge resonance energy asymmetrically broadens with
+decreasing temperature in its multi-q state. In contrast, insulating CaFeO3 has
+a symmetric scattering peak with an intensity 10x weaker than SrFeO3. Enhanced
+magnetic scattering at O K edge prepeak energies demonstrates the role of a
+negative charge transfer energy and the resulting oxygen ligand holes in the
+magnetic ordering of these ferrates. By measuring magnetic diffraction of
+CaFeO3/SrFeO3 superlattices with thick CaFeO3 layers, we find that the CaFeO3
+helical ordering is coherent across 1 unit cell-thick SrFeO3 layers but not 6
+unit cell-thick layers. We conclude that insulating CaFeO3 supports only a
+simple single-q helical structure in contrast to metallic SrFeO3 that hosts
+multi-q structures. Our results provide important insight into the role of
+electron itinerancy in the formation of multi-q spin structures.",1906.09998v1
+2019-09-30,Switching the Optical Chirality in Magneto-plasmonic Metasurfaces Using Applied Magnetic Fields,"Chiral nanophotonic devices are promising candidates for chiral molecules
+sensing, polarization diverse nanophotonics and display technologies. Active
+chiral nanophotonic devices, where the optical chirality can be controlled by
+an external stimulus has triggered great research interest. However, efficient
+modulation of the optical chirality has been challenging. Here, we demonstrate
+switching of the extrinsic chirality by applied magnetic fields in a
+magneto-plasmonic metasurface device based on a magneto-optical oxide material,
+Ce1Y2Fe5O12 (Ce:YIG). Thanks to the low optical loss and strong magneto-optical
+effect of Ce:YIG, we experimentally demonstrated a giant and continuous
+far-field circular dichroism (CD) modulation by applied magnetic fields from
+-0.65{\deg} to +1.9{\deg} at 950 nm wavelength under glancing incident
+conditions. The far field CD modulation is due to both magneto-optical circular
+dichroism and near-field modulation of the superchiral fields by applied
+magnetic fields. Finally, we demonstrate magnetic field tunable chiral imaging
+in millimeter-scale magneto-plasmonic metasurfaces fabricated using
+self-assembly. Our results provide a new way for achieving planar integrated,
+large-scale and active chiral metasurfaces for polarization diverse
+nanophotonics.",1909.13605v1
+2019-10-03,"Correlating the nanoscale structural, magnetic and magneto-transport properties in SrRuO3-based perovskite oxide ultra-thin films","We investigated the structural and magnetic properties of bare SrRuO$_3$
+(SRO) ultra-thin films and SrRuO$_3$/SrIrO$_3$/SrZrO$_3$ (SRO/SIO/SZO: RIZ)
+trilayer heterostructures between 10 K and 80 K, by comparing macroscopic data
+using magneto-optical Kerr effect (MOKE) and magneto-transport (anomalous Hall
+effect: AHE), with nanoscale fingerprints when applying non-contact scanning
+force microscopy (nc-SFM) and magnetic force microscopy (MFM). SRO and RIZ
+ultra-thin films were epitaxially grown at 650C onto vicinal SrTiO$_3$ (100)
+single-crystalline substrates to a nominal thickness of 4 and 4/2/2 unit cells
+(uc), respectively. Our correlated analysis allows associating topographic
+sample features of overgrown individual layers to their residual magnetization,
+as is shown here to be relevant for interpreting the macroscopic AHE data.
+Although the hump-like features in the AHE suggest a magnetically extured
+skyrmion phase to exist around 55 K associated to the topological Hall effect
+(THE), both our MOKE and MFM data cannot support this theory. In contrast, our
+SFM/MFM local-scale analysis finds the local coercive field to be strongly
+dependent on the effective layer thickness and stoichiometry in both the SRO
+and RIZ samples, with huge impact on the local band-structure. In fact, it is
+these variations that in turn mimic a potential THE through anomalies in the
+AHE resistivity loops.",1910.01474v1
+2019-10-04,Scale-invariant magnetic textures in the strongly correlated oxide NdNiO$_3$,"Strongly correlated quantum solids are characterized by an inherently
+granular electronic fabric, with spatial patterns that can span multiple length
+scales in proximity to a critical point. Here, we used a resonant magnetic
+X-ray scattering nanoprobe with sub-100 nm spatial resolution to directly
+visualize the texture of antiferromagnetic domains in NdNiO$_3$. Surprisingly,
+our measurements revealed a highly textured magnetic fabric, which is shown to
+be robust and nonvolatile even after thermal erasure across its ordering
+($T_{N\acute{e}el}$) temperature. The scale-free distribution of
+antiferromagnetic domains and its non-integral dimensionality point to a
+hitherto-unobserved magnetic fractal geometry in this system. These
+scale-invariant textures directly reflect the continuous nature of the magnetic
+transition and the proximity of this system to a critical point. The present
+study not only exposes the near-critical behavior in rare earth nickelates but
+also underscores the potential for novel X-ray scattering nanoprobes to image
+the multiscale signatures of criticality near a critical point.",1910.02072v1
+2020-04-21,Silica anchored colloidal suspension of magnetite nanorods,"This study focuses on the interaction of colloidal silica nanoparticles with
+the magnetite (Fe3O4) magnetic fluids (MF), which eventually forms nanorod like
+structure. The aqueous magnetic fluid consists of magnetite nanoparticles
+having double layers of lauric acid surfactants. This surfactant provides
+stability towards short-range van der Waals attractive and steric repulsive
+forces, as well as long-range dipole-dipole interactive force. Whereas, in the
+colloidal silica, the sodium ions provide stability to the silica
+nanoparticles. The colloidal silica and magnetic fluid both were mixed in
+different proportions to understand the interaction between the silica and
+magnetite nanoparticles. Thus, the interaction present in the system is studied
+using FTIR, TGA, and magnetic field induced microscopy. The FTIR and TGA data
+reveal that silica interacts with the outer layer of lauric acid through the
+Si-O bond and eventually provides stability to the system. The length of the
+lauric acid sheath varies with the concentration of silica nanoparticles. The
+SEM images indicate nanorod formation, and its structure dimensions vary with
+the silica concentrations, which is also reflected in the magnetic
+field-induced structure formations. The structure observed using microscopy
+correlated with the interaction derived from FTIR and TGA data analysis. XRD
+data of iron oxide (magnetite) nanoparticles are present here again for
+completion.",2004.09944v2
+2000-06-28,The connection between superconducting phase correlations and spin excitations in YBa$_2$Cu$_3$O$_{6.6}$: A magnetic field study,"One of the most striking universal properties of the
+high-transition-temperature (high-$T_c$) superconductors is that they are all
+derived from the hole-doping of their insulating antiferromagnetic (AF) parent
+compounds. From the outset, the intimate relationship between magnetism and
+superconductivity in these copper-oxides has intrigued researchers. Evidence
+for this link comes from neutron scattering experiments that show the
+unambiguous presence of short-range AF correlations (excitations) in cuprate
+superconductors. Even so, the role of such excitations in the pairing mechanism
+and superconductivity is still a subject of controversy. For
+YBa$_2$Cu$_3$O$_{6+x}$, where $x$ controls the hole-doping level, the most
+prominent feature in the magnetic excitations spectra is the ``resonance''.
+Here we show that for underdoped YBa$_2$Cu$_3$O$_{6.6}$, where $x$ and $T_c$
+are below the optimal values, modest magnetic fields suppress the resonance
+significantly, much more so for fields approximately perpendicular rather than
+parallel to the CuO$_2$ planes. Our results indicate that the resonance
+measures pairing and phase coherence, suggesting that magnetism plays an
+important role in the superconductivity of cuprates. The persistence of a field
+effect above $T_c$ favors mechanisms with preformed pairs in the normal state
+of underdoped cuprates.",0006433v1
+2019-01-04,Anisotropies and magnetic phase transitions in insulating antiferromagnets determined by a Spin-Hall magnetoresistance probe,"We demonstrate that we can determine the antiferromagnetic anisotropies and
+the bulk Dzyaloshinskii-Moriya fields of the insulating iron oxide hematite,
+{\alpha}-Fe2O3, using a surface sensitive spin-Hall magnetoresistance (SMR)
+technique. We develop an analytical model that in combination with SMR
+measurements, allow for the identification of the material parameters of this
+prototypical antiferromagnet over a wide range of temperatures and magnetic
+field values. Using devices with different orientations, we demonstrate that
+the SMR response strongly depends on the direction of the charge current with
+respect to the magneto-crystalline anisotropies axis. We show that we can
+extract the anisotropies over a wide temperature range including across the
+Morin phase transition. We observe that the electrical response is dominated by
+the orientation of the antiferromagnetic N\'eel order parameter, rather than by
+the emergent weak magnetic moment. Our results highlight that the surface
+sensitivity of the SMR allows accessing the magnetic anisotropies of
+antiferromagnetic crystals and in particular thin films where other methods to
+determine anisotropies such as bulk-sensitive magnetic susceptibility
+measurements do not provide sufficient sensitivity.",1901.01213v1
+2019-04-02,Magnetoelectrically driven catalytic degradation of organics,"Here, we report the catalytic degradation of organic compounds by exploiting
+the magnetoelectric (ME) nature of cobalt ferrite-bismuth ferrite (CFO-BFO)
+core-shell nanoparticles. The combination of magnetostrictive CFO with the
+multiferroic BFO gives rise to a magnetoelectric engine that purifies water
+under wireless magnetic fields via advanced oxidation processes, without
+involvement of any sacrificial molecules or co-catalysts. Magnetostrictive
+CoFe2O4 nanoparticles are fabricated using hydrothermal synthesis, followed by
+sol-gel synthesis to create the multiferroic BiFeO3 shell. We perform
+theoretical modeling to study the magnetic field induced polarization on the
+surface of magnetoelectric nanoparticles. The results obtained from these
+simulations are consistent with the experimental findings of the piezo-force
+microscopy analysis, where we observe changes in the piezoresponse of the
+nanoparticles under magnetic fields. Next, we investigate the magnetoelectric
+effect induced catalytic degradation of organic pollutants under AC magnetic
+fields and obtained 97% removal efficiency for synthetic dyes and over 85%
+removal efficiency for routinely used pharmaceuticals. Additionally, we perform
+trapping experiments to elucidate the mechanism behind the magnetic field
+induced catalytic degradation of organic pollutants by using scavengers for
+each of the reactive species. Our results indicate that hydroxyl and superoxide
+radicals are the main reactive species in the magnetoelectrically induced
+catalytic degradation of organic compounds.",1904.01271v1
+2019-11-01,Electric-Field Control of the Interlayer Exchange Coupling for Magnetization Switching,"We propose an electric-field-controlled mechanism for magnetization switching
+assisted solely by the interlayer-exchange coupling (IEC) between the fixed and
+the free magnets, which are separated by two oxide barriers sandwiching a
+spacer material known for exhibiting large IEC. The basic idea relies on the
+formation of a quantum-well (QW) within the spacer material and controlling the
+transmission coefficient across the structure with an electric-field via the
+resonant tunneling phenomena. Using non-equilibrium Green's function (NEGF)
+method, we show that the structure can exhibit a bias-dependent oscillatory IEC
+that can switch the free magnet to have either a parallel or an antiparallel
+configuration with respect to the fixed magnet, depending on the sign of the
+IEC. Such bi-directional switching can be achieved with the same voltage
+polarity but different magnitudes. With proper choice of the spacer material,
+the current in the structure can be significantly reduced. Due to the
+conservative nature of the exerted torque by the IEC, the switching threshold
+of the proposed mechanism is decoupled from the switching speed, while the
+conventional spin-torque devices exhibit a trade-off due to the
+non-conservative nature of the exerted torque.",1911.00183v1
+2020-03-10,Room-temperature ferrimagnetism of anti-site-disordered Ca2MnOsO6,"Room-temperature ferrimagnetism was discovered for the anti-site-disordered
+perovskite Ca2MnOsO6 with Tc = 305 K. Ca2MnOsO6 crystallizes into an
+orthorhombic structure with a space group of Pnma, in which Mn and Os share the
+oxygen-coordinated-octahedral site at an equal ratio without a noticeable
+ordered arrangement. The material is electrically semiconducting with
+variable-range-hopping behavior. X-ray absorption spectroscopy confirmed the
+trivalent state of the Mn and the pentavalent state of the Os. X-ray magnetic
+circular dichroism spectroscopy reveals that the Mn and Os magnetic moments are
+aligned antiferromagnetically, thereby classifying the material as a
+ferrimagnet which is in accordance with band structure calculations. It is
+intriguing that the magnetic signal of the Os is very weak, and that the
+observed total magnetic moment is primarily due to the Mn. The Tc = 305 K is
+the second highest in the material category of so-called disordered
+ferromagnets such as CaRu1-xMnxO3, SrRu1-xCrxO3, and CaIr1-xMnxO3, and hence,
+may support the development of spintronic oxides with relaxed requirements
+concerning the anti-site disorder of the magnetic ions.",2003.04608v1
+2020-05-17,Salt-Driven Assembly of Magnetic Silica Microbeads with Tunable Porosity,"Porous magnetic silica beads are promising materials for biological and
+environmental applications due to their enhanced adsorption and ease of
+recovery. This work aims to develop a new, inexpensive and environmentally
+friendly approach based on agglomeration of nanoparticles in aqueous droplets.
+The use of an emulsion as a geometrical constraint is expected to result in the
+formation of spherical beads with tunable composition depending on the aqueous
+phase content. Magnetic silica beads are produced at room temperature by
+colloidal destabilization induced by addition of calcium chloride to a
+water-in-oil emulsion containing silica and iron oxide nanoparticles. The
+impact of the salt concentration, emulsification method, concentration of
+hydrophobic surfactant as well as silica content is presented in this paper.
+This method enables the production of spherical beads with diameters between 1
+and 9 micrometers. The incorporation of magnetic nanoparticles inside the beads
+structure is confirmed using Energy Dispersive X-ray spectrometry and Scanning
+Transmission Electron Microscopy and results in the production of magnetic
+responsive beads with a preparation yield up to 84 percent. By incorporating
+the surfactant Span 80 in the oil phase it is possible to tune the roughness
+and porosity of the beads.",2005.08192v1
+2021-08-09,Spin-orbit effects in pentavalent Iridates: Models and materials,"Spin-orbit effects in heavy 5$d$ transition metal oxides, in particular,
+iridates, have received enormous current interest due to the prediction as well
+as the realization of a plethora of exotic and unconventional magnetic
+properties. While a bulk of these works are based on tetravalent iridates
+($d^5$), where the counter-intuitive insulating state of the rather extended
+5$d$ orbitals are explained by invoking strong spin-orbit coupling, the recent
+quest in iridate research has shifted to the other valencies of Ir, of which
+pentavalent iridates constitute a notable representative. In contrast to the
+tetravalent iridates, spin-orbit entangled electrons in $d^4$ systems are
+expected to be confined to the $J = 0$ singlet state without any resultant
+moment or magnetic response. However, it has been recently predicted that,
+magnetism in $d^4$ systems may occur via magnetic condensation of excitations
+across spin-orbit-coupled states. In reality, the magnetism in Ir$^{5+}$
+systems are often quite debatable both from theoretical as well as experimental
+point of view. Here we provide a comprehensive overview of the spin-orbit
+coupled $d^4$ model systems and its implications in the studied pentavalent
+iridates. In particular, we review here the current experimental and
+theoretical understanding of the double perovskite ($A_2B$YIrO$_6$, $A =$ Sr,
+Ba, $B =$Y, Sc, Gd), 6H-perovskite (Ba$_3M$Ir$_2$O$_9$, $M =$ Zn, Mg, Sr, Ca),
+post-perovskite (NaIrO$_3$), and Hexagonal (Sr$_3$MIrO$_6$) iridates, along
+with a number of open questions that require future investigation.",2108.04158v1
+2021-09-16,Giant shifts of crystal-field excitations in ErFeO3 driven by internal magnetic fields,"Due to the complex interactions between rare-earth elements and transition
+metals, as well as/or themselves, rare-earth transition-metal oxides are likely
+to exhibit highly intriguing and novel magnetic structures and dynamic
+behaviours. Rare-earth elements in these compounds frequently demonstrate
+unusual behaviours in their crystal-field (CF) excitations, which necessitate
+thorough research for in-depth comprehensions. When cooling from 10 K to 1.5 K
+via the magnetic ordering temperature of Er3+ at 4.1 K, we observed a
+significant energy shift of the low-lying CF excitation of Er3+ in ErFeO3 from
+0.35 meV to 0.75 meV utilizing the inelastic neutron-scattering technique. A
+sound CF model was proposed for Er3+ in ErFeO3 by fitting to the observed CF
+excitation peaks, which enables to explain all the observed experimental
+results in a very consistent manner. According to the model, the ground crystal
+field level of Er3+, which corresponds to the lowest Kramers doublet supposed
+to be at zero energy, has been shifted by the internal magnetic fields induced
+by both Er3+ and Fe3+ spin orders below and above the Er3+ ordering
+temperature, respectively. Additional measurements in various magnetic fields
+offer compelling evidence in favour of this hypothesis. The measured external
+field dependence of the CF excitation energy led to the derivation of the
+internal field of Er3+ as 0.33 meV, which is strongly corroborated by
+theoretical modelling. Additionally, the effective g-factor for Er3+ in ErFeO3
+showed an exceptionally significant anisotropy.",2109.07667v2
+2022-05-23,Direct Determination of Spin-Splitting Energy in Magnetic Graphene by Landau Fan Shifts,"Spin-polarized two-dimensional materials with large and tunable
+spin-splitting energy promise the field of 2D spintronics. While graphene has
+been a canonical 2D material, its spin properties and tunability are limited.
+Here, we demonstrate the emergence of robust spin-polarization in graphene with
+large and tunable spin-splitting energy of up to 132 meV at zero applied
+magnetic fields. The spin polarization is induced through a magnetic exchange
+interaction between graphene and the underlying ferrimagnetic oxide insulating
+layer, Tm3Fe5O12, as confirmed by its X-ray magnetic circular dichroism. The
+spin-splitting energies are directly measured and visualized by the shift in
+their landau fan diagram mapped by analyzing the measured subnikov-de-Haas
+oscillations as a function of applied electric fields, showing consistent fit
+with our first-principles and machine learning calculations. Further, the
+observed spin-splitting energies can be tuned over a broad range between 98 and
+166 meV by cooling fields. Our methods and results are applicable to other
+two-dimensional (magnetic) materials and heterostructures, and offer great
+potential for developing next-generation spin logic and memory devices.",2205.11042v2
+2022-06-06,Quantitative theory of magnetic interactions in solids,"In this report we review the method of explicit calculations of interatomic
+exchange interactions of magnetic materials. This involves exchange mechanisms
+normally referred to as Heisenberg exchange, Dzyaloshinskii-Moriya interaction
+and anisotropic symmetric exchange. The connection between microscopic theories
+of the electronic structure, such as density functional theory or dynamical
+mean field theory, and interatomic exchange, is given in detail. The different
+aspects of extracting information for an effective spin Hamiltonian that
+involves thousands of atoms, from electronic structure calculations considering
+significantly fewer atoms (1-50) is highlighted. Examples of exchange
+interactions of a large group of materials is presented, which involves heavy
+elements of the 3d period, alloys between transition metals, Heusler compounds,
+multilayer systems as well as overlayers and adatoms on a substrate, transition
+metal oxides, 4f elements, magnetic materials in two dimensions and molecular
+magnets. Where possible, a comparison to experimental data is made, that
+naturally becomes focused on the magnon dispersion. The influence of relativity
+is reviewed for a few cases, as is the importance of dynamical correlations.
+Development to theories that handle out of equilibrium conditions is also
+described here. The review ends with a short description of extensions of the
+theories behind explicit calculations of interatomic exchange, to non-magnetic
+situations, e.g. that describe chemical (charge) order and superconductivity.",2206.02415v2
+2022-06-16,Nodal superconducting exchange coupling,"The superconducting equivalent of giant magnetoresistance, involves placing a
+thin-film superconductor between two ferromagnetic layers. A change of
+magnetization-alignment in such a superconducting spin-valve from parallel (P)
+to antiparallel (AP) creates a positive shift in the superconducting transition
+temperature ({\Delta}Tc) due to an interplay of the magnetic exchange energy
+and the superconducting condensate. The magnitude of {\Delta}Tc scales
+inversely with the superconductor thickness (dS) and is zero when dS exceeds
+the superconducting coherence length ({\xi}) as predicted by de Gennes. Here,
+we report a superconducting spin-valve effect involving a different underlying
+mechanism that goes beyond de Gennes in which magnetization-alignment and
+{\Delta}Tc are determined by the nodal quasiparticle-excitation states on the
+Fermi surface of the d-wave superconductor YBa2Cu3O7-{\delta} (YBCO) grown
+between insulating layers of ferromagnetic Pr0.8Ca0.2MnO3. We observe
+{\Delta}Tc values that approach 2 K with {\Delta}Tc oscillating with dS over a
+length scale exceeding 100 {\xi} and, for particular values of dS, we find that
+the superconducting state reinforces an antiparallel magnetization-alignment.
+These results pave the way for all-oxide superconducting memory in which
+superconductivity modulates the magnetic state.",2206.07911v1
+2022-06-24,Traversing the pyrochlore stability diagram; microwave-assisted synthesis and discovery of mixed B-site Ln$_2$InSbO$_7$ family,"The lanthanide pyrochlore oxides Ln$_2$B$_2$O$_7$ are one of the most
+intensely studied classes of materials within condensed matter physics, firmly
+centered as one of the pillars of frustrated magnetism. The extensive chemical
+diversity of the pyrochlores, coupled with their innate geometric frustration,
+enables realization of a wide array of exotic and complex magnetic ground
+states. Thus, the discovery of new pyrochlore compositions has been a
+persistent theme that continues to drive the field in exciting directions. The
+recent focus on the mixed B-site pyrochlores offers a unique route towards
+tuning both local coordination chemistry and sterics, while maintaining a
+nominally pristine magnetic sublattice. Here, we present a broad overview of
+the pyrochlore stability field, integrating recent synthetic efforts in mixed
+B-site systems with the historically established Ln$_2$B$_2$O$_7$ families. In
+parallel, we present the discovery and synthesis of the entire Ln$_2$InSbO$_7$
+family (Ln: La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) located near
+the boundary of the pyrochlore stability field using a rapid, hybrid
+mechanicochemical/microwave-assisted synthesis technique. Magnetic
+characterization on the entire class of compounds draws striking parallels to
+the stannate analogs, suggesting that these compounds may host a breadth of
+exotic magnetic ground states.",2206.12022v1
+2022-09-21,Dynamics of photo-induced ferromagnetism in oxides with orbital degeneracy,"By using intense coherent electromagnetic radiation, it may be possible to
+manipulate the properties of quantum materials very quickly, or even induce new
+and potentially useful phases that are absent in equilibrium. For instance,
+ultrafast control of magnetic dynamics is crucial for a number of proposed
+spintronic devices and can also shed light on the possible dynamics of
+correlated phases out of equilibrium. Inspired by recent experiments on
+spin-orbital ferromagnet YTiO$_3$ we consider the nonequilibrium dynamics of
+Heisenberg ferromagnetic insulator with low-lying orbital excitations. We model
+the dynamics of the magnon excitations in this system following an optical
+pulse which resonantly excites infrared-active phonon modes. As the phonons
+ring down they can dynamically couple the orbitals with the low-lying magnons,
+leading to a dramatically modified effective bath for the magnons. We show this
+transient coupling can lead to a dynamical acceleration of the magnetization
+dynamics, which is otherwise bottlenecked by small anisotropy. Exploring the
+parameter space more we find that the magnon dynamics can also even completely
+reverse, leading to a negative relaxation rate when the pump is blue-detuned
+with respect to the orbital bath resonance. We therefore show that by using
+specially targeted optical pulses, one can exert a much greater degree of
+control over the magnetization dynamics, allowing one to optically steer
+magnetic order in this system. We conclude by discussing interesting parallels
+between the magnetization dynamics we find here and recent experiments on
+photo-induced superconductivity, where it is similarly observed that depending
+on the initial pump frequency, an apparent metastable superconducting phase
+emerges.",2209.10567v1
+2023-02-07,What can one learn about Fe-Cr alloys using Mössbauer spectroscopy?,"Applications of the M\""ossbauer spectroscopy (MS) in the investigation of
+Fe-Cr alloys are reviewed. A high sensitivity of the hyperfine magnetic field
+to the presence of Cr atoms in the vicinity of the probe Fe atoms permits
+quantitative investigation of various aspects related both to the
+crystallographic as well as to the magnetic phase diagram of this alloy system.
+Concerning the former, presented is the relevance of MS for determining borders
+of the miscibility gap and kinetics of the phase decomposition, distinguishing
+between nucleation and growth and spinodal decomposition, identifying the
+sigma-phase and studying kinetics of its precipitation. Regarding the magnetic
+phase diagram, MS is useful for determining the Curie, the N\'eel and the
+spin-freezing temperature, hence studying paramagnetic-ferromagnetic,
+paramagnetic-antiferromagnetic and paramagnetic-spin-glass transitions. An
+effect of different heat treatments, strain and irradiation with various
+particles on a distribution of Cr atoms in the Fe matrix is demonstrated, too.
+For bcc-FeCr alloys relevance of MS for determining changes in spin and charge
+densities at Fe-sites induced by neighboring Cr atoms is illustrated, as well
+as its usefulness in studying changes caused by a high-temperature sulphidation
+and oxidation. Concerning properties of sigma-FeCr alloys the application of MS
+for determining the Curie and Debye temperature is reviewed. Application of MS
+to study an effect of magnetism on the lattice dynamics of Fe atoms in
+sigma-FeCr is also exemplified. Last but not least, determining a magnetic
+texture and mechanical alloying is addressed.",2302.03436v1
+2023-03-14,The unusual distribution of spin-triplet supercurrents in disk-shaped Josephson junctions,"The phenomenon of s-wave spin triplet Cooper pairs induced in ferromagnetic
+metals has been researched now for more than a decade, and its main aspects are
+well understood. Crucial in converting s-wave singlet pairs in the
+superconductor to s-wave triplets in the ferromagnet is the engineering of
+well-defined magnetic inhomogeneity (the 'generator') at the interface with the
+superconductor. Vertical layer stacks are typically used as such, where two
+separate thin ferromagnetic layers with homogeneous but non-collinear
+magnetizations, provide the inhomogeneity. Alternatively, magnetic textures,
+like ferromagnetic domain walls and vortices, are possible triplet generators,
+although they are far less studied. In this paper we review our experiments on
+lateral disk-shaped Josephson junctions where a ferromagnetic bottom layer
+provides a weak link with a vortex magnetization imposed by the shape of the
+disk. We present three different junction configurations, exhibiting their own
+generator mechanism. In the first, we utilize the non-collinearity with a
+second ferromagnetic layer to produce the triplet correlations. The second
+configuration consists of only the bottom ferromagnet and the superconducting
+contacts; it relies on the vortex magnetization itself to generate the
+spin-polarized supercurrents. In the third case we exploit an intrinsic
+generator by combining a conventional superconductor (NbTi) and a half-metallic
+ferromagnetic oxide (La$_{0.7}$Sr$_{0.3}$MnO$_3$). We find strong supercurrents
+in all cases. A particularly interesting finding is that the supercurrents are
+strongly confined at the rims of the device, independent of the generating
+mechanism, but directly related to their triplet nature. What causes these rim
+currents remains an open question.",2303.07993v1
+2023-03-29,Light induced decoupling of electronic and magnetic properties in manganites,"The strongly correlated material La0.7Sr0.3MnO3 (LSMO) exhibits
+metal-to-insulator and magnetic transition near room temperature. Although the
+physical properties of LSMO can be manipulated by strain, chemical doping,
+temperature, or magnetic field, they often require large external stimuli. To
+include additional flexibility and tunability, we developed a hybrid
+optoelectronic heterostructure that uses photocarrier injection from cadmium
+sulfide (CdS) to an LSMO layer to change its electrical conductivity. LSMO
+exhibits no significant optical response, however, the CdS/LSMO
+heterostructures show an enhanced conductivity, with ~ 37 % resistance drop, at
+the transition temperature under light stimuli. This enhanced conductivity in
+response to light is comparable to the effect of a 9 T magnetic field in pure
+LSMO. Surprisingly, the optical and magnetic responses of CdS/LSMO
+heterostructures are decoupled and exhibit different effects when both stimuli
+are applied. This unexpected behavior shows that heterostructuring strongly
+correlated oxides may require a new understanding of the coupling of physical
+properties across the transitions and provide the means to implement new
+functionalities.",2303.17049v1
+2023-04-11,Syntropic spin alignment at the interface between ferromagnetic and superconducting nitrides,"The magnetic correlations at the superconductor/ferromagnet (S/F) interfaces
+play a crucial role in realizing dissipation-less spin-based logic and memory
+technologies, such as triplet-supercurrent spin-valves and ""{\pi}"" Josephson
+junctions. Here we report the coexistence of an induced large magnetic moment
+and a crypto ferromagnetic state at high-quality nitride S/F interfaces. Using
+polarized neutron reflectometry and d. c. SQUID measurements, we quantitatively
+determined the magnetization profile of S/F bilayer and confirmed the induced
+magnetic moment in the adjacent superconductor only exists below TC.
+Interestingly, the direction of the induced moment in the superconductors was
+unexpectedly parallel to that in the ferromagnet, which contrasts with earlier
+findings in S/F heterostructures based on metals or oxides. The
+first-principles calculations verify the observed unusual interfacial spin
+texture is caused by the Heisenberg direct exchange coupling through d orbital
+overlapping and severe charge transfer across the interfaces. Our work
+establishes an incisive experimental probe for understanding the magnetic
+proximity behavior at S/F interfaces and provides a prototype epitaxial
+building block for superconducting spintronics.",2304.05234v1
+2023-04-11,Additive manufacturing of Ni-Mn-Sn shape memory Heusler alloy -- Microstructure and magnetic properties from powder to printed parts,"Ni-Mn-based Heusler alloys like Ni-Mn-Sn show an elastocaloric as well as
+magnetocaloric effect during the magneto-structural phase transition, making
+this material interesting for solid-state cooling application. Material
+processing by additive manufacturing can overcome difficulties related to
+machinability of the alloys, caused by their intrinsic brittleness. Since the
+magnetic properties and transition temperature are highly sensitive to the
+chemical composition, it is essential to understand and monitoring these
+properties over the entire processing chain. In the present work the
+microstructural and magnetic properties from gas-atomized powder to
+post-processed Ni-Mn-Sn alloy are investigated. Direct energy deposition was
+used for processing, promoting the evolution of a polycrystalline
+microstructure being characterized by elongated grains along the building
+direction. A complete and sharp martensitic transformation can be achieved
+after applying a subsequent heat treatment at 1173 K for 24 h. The
+Mn-evaporation of 1.3 at. % and the formation of Mn-oxide during DED-processing
+lead to an increase of the transition temperature of 45 K and a decrease of
+magnetization, clearly pointing at the necessity of controlling the
+composition, oxygen partial pressure and magnetic properties over the entire
+processing chain.",2304.05383v1
+2023-06-08,Influence of native defects on magneto-optoelectronic properties of $α$-MoO$_{3}$,"Semiconducting oxides possess a variety of intriguing electronic, optical,
+and magnetic properties, and native defects play a crucial role in these
+systems. In this study, we study the influence of native defects on these
+properties of $\alpha$-MoO$_{3}$ using the first-principles density functional
+theory (DFT) calculations. From the formation energy calculations, it is
+concluded that Mo vacancies are difficult to form in the system, while O and
+Mo-O co-vacancies are energetically quite favorable. We further find that
+vacancies give rise to mid-gap states (trap states) that remarkably affect the
+magneto-optoelectronic properties of the material. Our calculations indicate
+that a single Mo vacancy leads to half-metallic behavior, and also induces a
+large magnetic moment of 5.98 $\mu_{B}$. On the other hand, for the single O
+vacancy case, the band gap disappears completely, but the system remains in a
+non-magnetic state. For Mo-O co-vacancies of two types considered in this work,
+a reduced band gap is found, along with an induced magnetic moment of 2.0
+$\mu_{B}$. Furthermore, a few finite peaks below the main band edge are
+observed in the absorption spectra of configurations with Mo and O vacancies,
+while they are absent in the Mo-O co-vacancies of both types, just like in the
+pristine state. From the ab-initio molecular dynamics simulations, stability
+and sustainability of induced magnetic moment at room temperate is verified.
+Our findings will enable the development of defect strategies that maximize the
+functionality of the system, and further help in designing highly efficient
+magneto-optoelectronic and spintronic devices.",2306.04978v1
+2023-11-01,Large Energy Shifts of Crystal-field Excitations in Erbium Orthoferrite Driven by Internal Magnetic Fields,"Due to the complex interactions between rare-earth elements and transition
+metals, as well as between themselves, rare-earth transition-metal oxides are
+likely to exhibit highly intriguing and novel magnetic structures and dynamic
+behaviours. Rare-earth elements in these compounds frequently demonstrate
+unusual behaviours in their crystal-field (CF) excitations, which necessitate
+thorough studies for in-depth comprehensions. When cooling from 10 K to 1.5 K
+through the magnetic ordering temperature of $Er^{3+}$ at 4.1 K, we observed a
+significant energy shift of the low-lying CF excitation of $Er^{3+}$ in erbium
+orthoferrite ($ErFeO_3$) from 0.32 meV to 0.75 meV utilizing the inelastic
+neutron-scattering technique. A sound CF model was proposed for $Er^{3+}$ in
+$ErFeO_3$ by fitting to the observed CF excitation peaks, which enables to
+explain all the observed experimental results in a very consistent manner.
+According to the model, the ground crystal field level of $Er^{3+}$, which
+corresponds to the lowest Kramers doublet supposed to be at zero energy
+transfer, has been shifted by the internal magnetic fields induced by both
+$Er^{3+}$ and $Fe^{3+}$ spin orders below and above the $Er^{3+}$ ordering
+temperature, respectively. Additional measurements in various magnetic fields
+offer compelling evidence in favour of this hypothesis. The measured external
+field dependence of the CF excitation energy led to a derivation of the
+internal field of $Er^{3+}$ as 0.54 T, which is strongly corroborated by
+theoretical modelling. Additionally, the g-factor for the $Er^{3+}$ ground
+state in $ErFeO_3$ shows an exceptionally significant anisotropy.",2311.00478v1
+2015-06-18,Evolution of electronic states in n-type copper oxide superconductor via electric double layer gating,"Since the discovery of n-type copper oxide superconductors, the evolution of
+electron- and hole-bands and its relation to the superconductivity have been
+seen as a key factor in unveiling the mechanism of high-Tc superconductors. So
+far, the occurrence of electrons and holes in n-type copper oxides has been
+achieved by chemical doping, pressure, and/or deoxygenation. However, the
+observed electronic properties are blurred by the concomitant effects such as
+change of lattice structure, disorder, etc. Here, we report on successful
+tuning the electronic band structure of n-type Pr2-xCexCuO4 (x = 0.15)
+ultrathin films, via the electric double layer transistor technique. Abnormal
+transport properties, such as multiple sign reversals of Hall resistivity in
+normal and mixed states, have been revealed within an electrostatic field in
+range of -2 V to +2 V, as well as varying the temperature and magnetic field.
+In the mixed state, the intrinsic anomalous Hall conductivity invokes the
+contribution of both electron and hole-bands as well as the energy dependent
+density of states near the Fermi level. The two-band model can also describe
+the normal state transport properties well, whereas the carrier concentrations
+of electrons and holes are always enhanced or depressed simultaneously in
+electric fields. This is in contrast to the scenario of Fermi surface
+reconstruction by antiferromagnetism, where an anti-correlation between
+electrons and holes is commonly expected. Our findings paint the picture where
+Coulomb repulsion plays an important role in the evolution of the electronic
+states in n-type cuprate superconductors.",1506.05727v1
+2018-02-23,Tuning the electronic and chemisorption properties of hexagonal MgO nanotubes by doping - Theoretical study,"Oxide materials offer a wide range of interesting physical and chemical
+properties. Even more versatile behavior of oxides is seen at the nanoscale,
+qualifying these materials for a number of applications. In this study we used
+DFT calculations to investigate the physical and chemical properties of small
+hexagonal MgO nanotubes of different length. We analyzed the effect of Li, B,
+C, N, and F doping on the properties of the nanotubes. We find that all dopants
+favor the edge positions when, incorporated into the nanotubes. Doping results
+in the net magnetization whose value depends on the type of the impurity. Using
+the CO molecule as a probe, we studied the adsorption properties of pristine
+and doped MgO nanotubes. Our results show that the dopant sites are also the
+centers of significantly altered chemical reactivity. While pristine MgO
+nanotubes adsorb CO weakly, very strong adsorption at the dopant sites (B-, C-,
+and N-doped nanotubes) or neighboring edge atoms (F- and Li-doped nanotubes) is
+observed. Our results suggest that impurity engineering in oxide materials can
+be a promising strategy for the development of novel materials with possible
+use as selective adsorbents or catalysts.",1802.08440v2
+2018-11-22,Oxygen-Octahedral-Tilting-Driven Topological Hall Effect in Ultrathin SrRuO3 Films,"Topological spin textures as an emerging class of topological matter offer a
+medium for information storage and processing. The recently discovered
+topological Hall effect (THE) is considered as a fingerprint for electrically
+probing non-trivial spin-textures. But the origin of THE in oxides has remained
+elusive. Here we report an observation of the THE in ultrathin (unit cells.
+u.c.) 4d ferromagnetic SrRuO3 films grown on SrTiO3(001) substrates, which can
+be attributed to the chiral ordering of spin structure (i.e., skyrmion-like) in
+the single SrRuO3 layer without contacting 5d oxide SrIrO3 layer. It is
+revealed that the RuO6 octahedral tilting induced by local
+orthorhombic-to-tetragonal structural phase transition exists across the
+SrRuO3/SrTiO3 interface, which naturally breaks the inversion symmetry. Our
+theoretical calculations demonstrate that the Dzyaloshinskii-Moriya (DM)
+interaction arises owing to the broken inversion symmetry and strong spin-orbit
+interaction of 4d SrRuO3. This DM interaction can stabilize the N\'eel-type
+magnetic skyrmions, which in turn accounts for the observed THE in transport.
+The RuO6 octahedral tilting-induced DM interaction provides a pathway toward
+the electrical control of the topological spin textures and resultant THE,
+which is confirmed both experimentally and theoretically. Besides the
+fundamental significance, the understanding of THE in oxides and its electrical
+manipulation presented in this work could advance the low power cost
+topological electronic and spintronic applications.",1811.09075v1
+2017-11-02,Converged GW quasiparticle energies for transition metal oxide perovskites,"The ab initio calculation of quasiparticle (QP) energies is a technically and
+computationally challenging problem. In condensed matter physics the most
+widely used approach to determine QP energies is the GW approximation. Although
+the GW method has been widely applied to many typical semiconductors and
+insulators, its application to more complex compounds such as transition metal
+oxide perovskites has been comparatively rare, and its proper use is not well
+established from a technical point of view. In this work, we have applied the
+single-shot G0W0 method to a representative set of transition metal oxide
+perovskites including 3d (SrTiO3, LaScO3, SrMnO3, LaTiO3, LaVO3, LaCrO3,
+LaMnO3, and LaFeO3), 4d (SrZrO3, SrTcO3, and Ca2RuO4) and 5d (SrHfO3, KTaO3 and
+NaOsO3) compounds with different electronic configurations, magnetic orderings,
+structural characteristics and bandgaps ranging from 0.1 to 6.1 eV. We discuss
+the proper procedure to obtain well converged QP energies and accurate bandgaps
+within single-shot G0W0 by comparing the conventional approach based on an
+incremental variation of a specific set of parameters (number of bands, energy
+cutoff for the plane-wave expansion and number of k-points and the basis-set
+extrapolation scheme [Phys. Rev. B 90, 075125 (2014)]. In addition, we have
+inspected the difference between the adoption of norm-conserving and ultrasoft
+potentials in GW calculations. A minimal statistical analysis indicates that
+the correlation of the GW data with the DFT gap is more robust than the
+correlation with the experimental gaps; moreover we identify the static
+dielectric constant as alternative useful parameter for the approximation of GW
+gap in high-throughput automatic procedures. Finally, we compute the QP band
+structure and spectra within the random phase approximation and compare the
+results with available experimental data.",1711.00916v3
+2021-08-17,Spin-charge interconversion in KTaO$_3$ two-dimensional electron gases,"Oxide interfaces exhibit a broad range of physical effects stemming from
+broken inversion symmetry. In particular, they can display non-reciprocal
+phenomena when time reversal symmetry is also broken, e.g., by the application
+of a magnetic field. Examples include the direct and inverse Edelstein effects
+(DEE, IEE) that allow the interconversion between spin currents and charge
+currents. The DEE and IEE have been investigated in interfaces based on the
+perovskite SrTiO$_3$ (STO), albeit in separate studies focusing on one or the
+other. The demonstration of these effects remains mostly elusive in other oxide
+interface systems despite their blossoming in the last decade. Here, we report
+the observation of both the DEE and IEE in a new interfacial two-dimensional
+electron gas (2DEG) based on the perovskite oxide KTaO$_3$. We generate 2DEGs
+by the simple deposition of Al metal onto KTaO$_3$ single crystals,
+characterize them by angle-resolved photoemission spectroscopy and
+magnetotransport, and demonstrate the DEE through unidirectional
+magnetoresistance and the IEE by spin-pumping experiments. We compare the
+spin-charge interconversion efficiency with that of STO-based interfaces,
+relate it to the 2DEG electronic structure, and give perspectives for the
+implementation of KTaO$_3$ 2DEGs into spin-orbitronic devices.",2108.07479v1
+2023-02-20,Observation of near room temperature thin film superconductivity of atmospherically stable Ag-Au mesoscopic thin film,"An environmentally stable mesoscopic thin film of Au of certain thickness has
+been deposited thermally on top of a Ag+ implanted oxide substrate to develop a
+close to room temperature superconductor. This thin film has been deposited in
+two different stages. Initially, a sol-gel derived ion conducting metal oxide
+(ICMO) thin film has been deposited by spin coating. Afterward, Ag+ has been
+introduced inside ICMO thin film by a chemical method. Following this, a thin
+layer of Au has been deposited on top of that Ag ion-implanted oxide via
+thermal evaporation. The temperature dependent resistivity (R-T) has been
+studied by four probe method. During high-to-low temperature sweep, around 240
+K this thin film sample shows a sudden drop of resistance from 0.7 Ohm to 0.1
+micro-Ohm. This 6-7 orders drop of resistance has been observed instantly
+within <0.1 K temperature variation of the sample. This transition temperature
+(TC) has been shifted toward the higher temperature by 5-6 degrees when
+temperature has been increased from low to the higher side. During 2nd and 3rd
+temperature cycling, both these transitions have been shifted by ~10 K towards
+room temperature w.r.t the earlier. However, after three successive temperature
+cycles, TC becomes stable and transitions occur close to 0 oC repeatedly. At
+the low resistance phase, current level has been varied from +100 mA to -100 mA
+which shows a random fluctuation of voltage drop within 10 nV range, indicating
+resistance under such circumstance is too low to measure by Delta mode
+electrical measurement (0.1 micro-Ohm). Besides, transition temperature reduces
+to lower temperature by 4 K, after applying 1 tesla magnetic field
+perpendicular to the thin film. Few YouTube video links of temperature
+dependent electrical characterization of such a thin film is given next to the
+acknowledgement section.",2302.09974v3
+1999-11-23,Charge ordering and long-range interactions in layered transition metal oxides: a quasiclassical continuum study,"The competition between long-range and short-range interactions among holes
+moving in an antiferromagnet (AF), is studied within a model derived from the
+spin density wave picture of layered transition metal oxides. A novel numerical
+approach is developed which allows one to solve the problem at finite hole
+densities in very large systems (of order hundreds of lattice spacings), albeit
+in a quasiclassical limit, and to correctly incorporate the long-range part of
+the Coulomb interaction. The focus is on the problem of charge ordering and the
+charge phase diagram: at low temperatures four different phases are found,
+depending on the strength of the magnetic (dipolar) interaction generated by
+the spin-wave exchange, and the density of holes. The four phases are the
+Wigner crystal, diagonal stripes, a grid phase (horizontal-vertical stripe
+loops) and a glassy-clumped phase. In the presence of both in-plane and
+out-of-plane charged impurities the stripe ordering is suppressed, although
+finite stripe segments persist. At finite temperatures multiscale
+(intermittency) dynamics is found, reminiscent of that in glasses. The dynamics
+of stripe melting and its implications for experiments is discussed.",9911380v2
+2004-10-26,Orbital Physics in the Perovskite Ti Oxides,"In the perovskite Ti oxide RTiO3 (R=rare-earth ions), the Ti t2g orbitals and
+spins in the 3d^1 state couple each other through the strong electron
+correlations, resulting in a rich variety of orbital-spin phases. The origin
+and nature of orbital-spin states of these Mott insulators have been
+intensively studied. In this article, we review the studies on orbital physics
+in the perovskite titanates. We focus on the following three topics: (1) the
+origin and nature of the ferromagnetism as well as the orbital ordering in the
+compounds with relatively small R ions such as GdTiO3 and YTiO3, (2) the origin
+of the G-type antiferromagnetism and the orbital state in LaTiO3, and (3) the
+orbital-spin structures in other AFM(G) compounds with relatively large R ions
+(R=Ce, Pr, Nd and Sm). On the basis of these discussions, we discuss the whole
+phase diagram together with mechanisms of the magnetic phase transition. We
+also show that the Ti t2g degeneracy is inherently lifted in the titanates,
+which allows the single-band descriptions of the ground-state and low-energy
+electronic structures as a good starting point. Our analyses indicate that
+these compounds offer touchstone materials described by the single-band Hubbard
+model on the cubic lattice. From this insight, we also reanalyze the hole-doped
+titanates. Experimentally revealed filling-dependent and bandwidth-dependent
+properties and the critical behavior of the metal-insulator transitions are
+discussed in the light of theories based on the single-band Hubbard models.",0410650v1
+2005-11-05,Polarons and confinement of electronic motion to two dimensions in a layered transition metal oxide,"A very remarkable feature of the layered transition metal oxides (TMOs),
+whose most famous members are the high-temperature superconductors (HTSs), is
+that even though they are prepared as bulk three-dimensional single crystals,
+they display hugely anisotropic electrical and optical properties, seeming to
+be insulating perpendicular to the layers and metallic within them. This is the
+phenomenon of confinement, a concept at odds with the conventional theory of
+solids and recognized as due to magnetic and electron-lattice interactions in
+the layers which must be overcome at a substantial energy cost if electrons are
+to be transferred between layers. The associated energy gap or 'pseudogap' is
+particularly obvious in experiments where charge is moved perpendicular to the
+planes, most notably scanning tunneling microscopy (STM) and polarized infrared
+spectroscopy. Here, using the same experimental tools, we show that there is a
+second family of TMOs - the layered manganites La2-2xSr1+2xMn2O7 (LSMO) - with
+even more extreme confinement and pseudogap effects. The data, which are the
+first to resolve atoms in any metallic manganite, demonstrate quantitatively
+that because they are attached to polarons - lattice and spin textures within
+the planes -, it is equally difficult to remove carriers from the planes via
+vacuum tunneling into a conventional metallic tip, as it is for them to move
+between Mn-rich layers within the material itself.",0511138v1
+2006-08-29,Correlation Energies in Distorted 3d-$t_{2g}$ Perovskite Oxides,"Using an effective low-energy Hamiltonian derived from the first-principles
+electronic structure calculations for the narrow $t_{2g}$ bands of YTiO$_3$,
+LaTiO$_3$, YVO$_3$, and LaVO$_3$, we evaluate the contributions of the
+correlation energy ($E_C$) to the stability of different magnetic structures,
+which can be realized in these distorted perovskite oxides. We consider two
+approximations for $E_C$, which are based on the regular perturbation theory
+expansion around a nondegenerate Hartree-Fock ground state. One is the second
+order of perturbation theory, which allows us to compare the effects of local
+and nonlocal correlations. Another one is the local $t$-matrix approach, which
+allows us to treat some higher-order contributions to $E_C$. The correlation
+effects systematically improve the agreement with the experimental data and
+additionally stabilize the experimentally observed $G$- and $C$-type
+antiferromagnetic (AFM) structures in YVO$_3$ and LaVO$_3$, though the absolute
+magnitude of the stabilization energy is sensitive to the level of
+approximations and somewhat smaller in the $t$-matrix method. The nonlocal
+correlations additionally stabilize the ferromagnetic ground state in YTiO$_3$
+and the $C$-type AFM ground state in LaVO$_3$. Amongst two inequivalent
+transition-metal sites in the monoclinic structure, the local correlations are
+stronger at the sites with the least distorted environment. Limitations of the
+regular perturbation-theory expansion for LaTiO$_3$ are also discussed.",0608625v1
+2008-01-15,Exchange Interaction and $T_c$ in Alkaline-earth-metal-oxide-based DMS without Magnetic Impurities: First Principle Pseudo-SIC and Monte Carlo Calculation,"The prospects of half-metallic ferromagnetism being induced by the
+incorporation of C atoms into alkaline-earth-metal-oxides are investigated by
+the first principle calculation. The origin of the ferromagnetism is discussed
+through the calculation of the electronic structure and exchange coupling
+constant by using the pseudo-potential-like self-interaction-corrected local
+spin density method. The Curie temperature ($T_c$) is also predicted by
+employing the Monte Carlo simulation. It is shown that by taking the electron
+self-interaction into account, the half-metallic ferromagnetism induced by C in
+the host materials is more stabilized in comparison with the standard LDA case,
+and the C's $2p$ electron states in the bandgap become more localized resulting
+in the predominance of the short-ranged exchange interaction. While the
+ferromagnetism in MgO$_{1-x}$C$_x$ is stabilized due to the exchange
+interaction of the $1st$-nearest neighbor pairs and might be suppressed by the
+anti-ferromagnetic super-exchange interaction at higher $x$, the ferromagnetism
+in CaO$_{1-x}$C$_x$, SrO$_{1-x}$C$_x$, and BaO$_{1-x}$C$_x$ is stabilized by
+both the $1st$- and $2nd$-nearest neighbor pairs, and $T_c$ monotonously
+increases with the C concentration.",0801.2249v1
+2008-06-02,Spin-singlet superconductivity with multiple gaps in PrO0.89F0.11FeAs,"Since the discovery of high transition-temperature (Tc) superconductivity in
+copper oxides two decades ago, continuous efforts have been devoted to
+searching for similar phenomenon in other compounds. With the exception of MgB2
+(Tc =39 K), however, Tc is generally far lower than desired. Recently,
+breakthrough has been made in a new class of oxypnictide compounds. Following
+the initial discovery of superconductivity in LaO1-x FxFeAs (Tc =26 K), Tc
+onset has been raised to 55 K in ReO1-xFxFeAs (Re: Ce, Pr, Nd, Sm). Meanwhile,
+unravelling the nature of the energy associated with the formation of
+current-carrying pairs (Cooper pairs), referred to as the superconducting
+energy gap, is the first and vital step towards understanding why the
+superconductivity occurs at such high temperature and is also important for
+finding superconductors with still higher Tc. Here we show that, on the basis
+of the nuclear magnetic resonance (NMR) measurements in PrO0.89F0.11FeAs (Tc
+=45 K), the Cooper pair is in the spin-singlet state (two spins are
+anti-paralleled), with two energy gaps opening below Tc. The results strongly
+suggest the existence of nodes (zeros) in the gap. None of superconductors
+known to date has such unique gap features, although copper-oxides and MgB2
+share part of them.",0806.0249v1
+2009-01-17,Electrostatic co-assembly of iron oxide nanoparticles and polymers : towards the generation of highly persistent superparamagnetic nanorods,"A paradigm proposed recently by Boal et al. (A.K. Boal et al., Nature 404,
+746-748, 2000) deals with the possibility to use inorganic nanoparticles as
+building blocks for the design and fabrication of colloidal and supracolloidal
+assemblies. It is anticipated that these constructs could be made of different
+shapes, patterns and functionalities and could constitute the components of
+future nanodevices including sensors, actuators or nanocircuits. Here we report
+a protocol that allowed us to fabricate such nanoparticle aggregates. The
+building blocks of the constructs were anionically coated iron oxide
+nanocrytals (superparamagnetic, size 7 nm) and cationic-neutral block
+copolymers. We have shown that the electrostatic interactions between charged
+species can be controlled by tuning the ionic strength of the dispersion. Under
+appropriate conditions, the control of electrostatics resulted in the
+elaboration of spherical or elongated aggregates at the micrometer length
+scale. The elongated aggregates were found to be rod-like, with diameters of a
+few hundred nanometers and lengths between 1 and 50 micrometers. In addition to
+their remarkable stiffness, the nanostructured rods were found to reorient
+along with an externally applied magnetic field, in agreement with the laws of
+superparamagnetism.",0901.2667v1
+2009-04-12,Long Range Coulomb Interactions and Nanoscale Electronic Inhomogeneities in Correlated Oxides,"Electronic, magnetic or structural inhomogeneities ranging in size from
+nanoscopic to mesoscopic scales seem endemic, and are possibly generic, to
+colossal magnetoresistance manganites and other transition metal oxides. We
+show here that an extension, to include long range Coulomb interactions, of a
+quantum two-fluid $\ell-b$ model proposed recently for manganites [Phys. Rev.
+Lett., {\bf 92}, 157203 (2004)] leads to an excellent description of such
+inhomogeneities. In the $\ell-b$ model two very different kinds of electronic
+states, one localized and polaronic ($\ell$), and the other extended or broad
+band ($b$) co-exist. For model parameters appropriate to manganites, and even
+within a simple dynamical mean-filed theory (DMFT) framework, it describes many
+of the unusual phenomena seen in manganites, including colossal
+magnetoresistance (CMR), qualitatively and quantitatively. However, in the
+absence of long ranged Coulomb interaction, a system described by such a model
+would actually phase separate, into macroscopic regions of $l$ and $b$
+electrons respectively. As we show in this paper, in the presence of Coulomb
+interactions, the {\em macroscopic} phase separation gets suppressed, and
+instead nanometer scale regions of polarons interspersed with band electron
+puddles appear, constituting a new kind of quantum Coulomb glass. Our work
+points to an interplay of strong correlations, long range Coulomb interaction
+and dopant ion disorder as the origin of nanoscale inhomogeneities, rather than
+disorder frustrated phase competition as is generally believed. Based on this,
+we argue that the observed micrometer(meso)-scale inhomogeneities owe their
+existence to extrinsic causes, eg. strain due to cracks and defects. We suggest
+possible experiments to validate our speculation.",0904.1886v1
+2010-08-16,"Second Homologous Series of Iron Pnictide Oxide Superconductors (Fe2As2)(Can+2(Al,Ti)nOy)[n = 2,3,4]","We have discovered a new homologous series of iron pnictide oxides
+(Fe2As2)(Can+2(Al,Ti)nOy)[n = 2,3,4]. These compounds have perovskite-like
+blocking layers between Fe2As2 layers. The structure of new compounds are
+tetragonal with space groups of P4/nmm for n = 2 and 4 and P4mm for n = 3,
+which are similar to those of (Fe2As2)(Can+1(Sc,Ti)nOy)[n = 3,4,5] found in our
+previous study. Compounds with n = 3 and 4 have new crystal structures with 3
+and 4 sheets of perovskite layers, respectively, including a rock salt layer in
+each blocking layer. The a-axis lengths of the three compounds are
+approximately 3.8 A, which are close to those of FeSe and LiFeAs.
+(Fe2As2)(Ca6(Al,Ti)4Oy) exhibited bulk superconductivity in magnetization
+measurement with Tc(onset)~36 K and resistivity drop was observed at ~39 K.
+(Fe2As2)(Ca5(Al,Ti)3Oy) also showed large diamagnetism at low temperatures.
+These new compounds indicate considerable rooms are still remaining for new
+superconductors in layered iron pnictides.",1008.2582v4
+2011-08-03,Link between spin fluctuations and Cooper pairing in copper oxide superconductors,"Although it is generally accepted that superconductivity (SC) is
+unconventional in the high- transition temperature copper oxides (high-Tc
+cuprates), the relative importance of phenomena such as spin and charge
+(stripe) order, SC fluctuations, proximity to a Mott insulator, a pseudogap
+phase, and quantum criticality are still a matter of great debate1. In
+electron-doped cuprates, the absence of an anomalous pseudogap phase in the
+underdoped region of the phase diagram2 and weaker electron correlations3,4,
+suggest that Mott physics and other unidentified competing orders are less
+relevant and that antiferromagnetic (AFM) spin fluctuations are the dominant
+feature. Here we demonstrate that a linear-temperature (T-linear) scattering
+rate - a key feature of the anomalous normal state properties of the cuprates -
+is correlated with the Cooper pairing (SC). Through a study of magnetotransport
+in thin films of the electron-doped cuprate La2 xCexCuO4 (LCCO), we show that
+an envelope of T-linear scattering surrounds the SC phase, and survives to zero
+temperature when superconductivity is suppressed by magnetic fields. Comparison
+with similar behavior found in organic superconductors5 strongly suggests that
+the T-linear resistivity is caused by spin-fluctuation scattering. Our results
+establish a fundamental connection between AFM spin fluctuations and the
+pairing mechanism of high temperature superconductivity in the cuprates.",1108.0940v1
+2012-06-06,The role of oxygen vacancies on the structure and the density of states of iron doped zirconia,"In this paper we study, both with theoretical and experimental approach, the
+effect of iron doping in zirconia. Combining density functional theory (DFT)
+simulations with the experimental characterization of thin films, we show that
+iron is in the Fe3+ oxidation state and accordingly that the films are rich in
+oxygen vacancies (VO). VO favor the formation of the tetragonal phase in doped
+zirconia (ZrO2:Fe) and affect the density of state at the Fermi level as well
+as the local magnetization of Fe atoms. We also show that the Fe(2p) and Fe(3p)
+energy levels can be used as a marker for the presence of vacancies in the
+doped system. In particular the computed position of the Fe(3p) peak is
+strongly sensitive to the VO to Fe atoms ratio. A comparison of the theoretical
+and experimental Fe(3p) peak position suggests that in our films this ratio is
+close to 0.5. Besides the interest in the material by itself, ZrO2:Fe
+constitutes a test case for the application of DFT on transition metals
+embedded in oxides. In ZrO2:Fe the inclusion of the Hubbard U correction
+significantly changes the electronic properties of the system. However the
+inclusion of this correction, at least for the value U = 3.3 eV chosen in the
+present work, worsen the agreement with the measured photo-emission valence
+band spectra.",1206.1197v4
+2012-07-12,Fingerprints of spin-orbital entanglement in transition metal oxides,"The concept of spin-orbital entanglement on superexchange bonds in transition
+metal oxides is introduced and explained on several examples. It is shown that
+spin-orbital entanglement in superexchange models destabilizes the long-range
+(spin and orbital) order and may lead either to a disordered spin-liquid state
+or to novel phases at low temperature which arise from strongly frustrated
+interactions. Such novel ground states cannot be described within the
+conventionally used mean field theory which separates spin and orbital degrees
+of freedom. Even in cases where the ground states are disentangled,
+spin-orbital entanglement occurs in excited states and may become crucial for a
+correct description of physical properties at finite temperature. As an
+important example of this behaviour we present spin-orbital entanglement in the
+$R$VO$_3$ perovskites, with $R$=La,Pr,...,Yb,Lu, where such finite temperature
+properties of these compounds can be understood only using entangled states:
+($i$) thermal evolution of the optical spectral weights, ($ii$) the dependence
+of transition temperatures for the onset of orbital and magnetic order on the
+ionic radius in the phase diagram of the $R$VO$_3$ perovskites, and ($iii$)
+dimerization observed in the magnon spectra for the $C$-type antiferromagnetic
+phase of YVO$_3$. Finally, it is shown that joint spin-orbital excitations in
+an ordered phase with coexisting antiferromagnetic and alternating orbital
+order introduces topological constraints for the hole propagation and will thus
+radically modify transport properties in doped Mott insulators where hole
+motion implies simultaneous spin and orbital excitations.",1207.3010v1
+2012-11-02,Topological phases in layered pyrochlore oxide thin films along the [111] direction,"We theoretically study a multi-band Hubbard model of pyrochlore oxides of the
+form A$_2$B$_2$O$_7$, where B is a heavy transition metal ion with strong
+spin-orbit coupling, in a thin film geometry orientated along the [111]
+direction. Along this direction, the pyrochlore lattice consists of alternating
+kagome and triangular lattice planes of B ions. We consider a single kagome
+layer, a bilayer, and the two different trilayers. As a function of the
+strength of the spin-orbit coupling, the direct and indirect $d$-orbital
+hopping, and the band filling, we identify a number of scenarios where a
+non-interacting time-reversal invariant Z$_2$ topological phase is expected and
+we suggest some candidate materials. We study the interactions in the
+half-filled $d$-shell within Hatree-Fock theory and identify parameter regimes
+where a zero magnetic field Chern insulator with Chern number $\pm1$ can be
+found. The most promising geometries for topological phases appear to be the
+bilayer which supports both a Z$_2$ topological insulator and a Chern
+insulator, and the triangular-kagome-triangular trilayer which supports a
+relatively robust Chern insulator phase.",1211.0562v2
+2013-03-06,ARPES: A probe of electronic correlations,"Angle-resolved photoemission spectroscopy (ARPES) is one of the most direct
+methods of studying the electronic structure of solids. By measuring the
+kinetic energy and angular distribution of the electrons photoemitted from a
+sample illuminated with sufficiently high-energy radiation, one can gain
+information on both the energy and momentum of the electrons propagating inside
+a material. This is of vital importance in elucidating the connection between
+electronic, magnetic, and chemical structure of solids, in particular for those
+complex systems which cannot be appropriately described within the
+independent-particle picture. Among the various classes of complex systems, of
+great interest are the transition metal oxides, which have been at the center
+stage in condensed matter physics for the last four decades. Following a
+general introduction to the topic, we will lay the theoretical basis needed to
+understand the pivotal role of ARPES in the study of such systems. After a
+brief overview on the state-of-the-art capabilities of the technique, we will
+review some of the most interesting and relevant case studies of the novel
+physics revealed by ARPES in 3d-, 4d- and 5d-based oxides.",1303.1438v1
+2014-08-18,Anomalous magnetoresistance in the spinel superconductor LiTi2O4,"Transition-metal oxides offer an opportunity to explore unconventional
+superconductors, where the superconductivity (SC) is often interrelated with
+novel phenomena such as spin/charge order, fluctuations, and Fermi surface
+instability (1-3). LiTi2O4 (LTO) is a unique compound in that it is the only
+known spinel oxide superconductor. In addition to electron-phonon coupling,
+electron-electron and spin fluctuation contributions have been suggested as
+playing important roles in the microscopic mechanism for its superconductivity
+(4-8). However, the lack of high quality single crystals has thus far prevented
+systematic investigation of their transport properties (9). Here, we report a
+careful study of transport and tunneling spectroscopy in epitaxial LTO thin
+films. In the superconducting state, the energy gap was found to decrease as a
+quadratic function of magnetic field. In the normal state, an unusual
+magnetoresistance (MR) was observed where it changes from anisotropic positive
+to isotropic negative as the temperature is increased. A constant charge
+carrier concentration without any abrupt change in lattice parameters as a
+function of temperature suggests that the isotropic MR stems from the
+suppression of spin scattering/fluctuations, while the anisotropic term
+originates from an orbital contribution. These observations point to an
+important role strong correlations play in this unique superconductor.",1408.3894v1
+2014-09-22,Analysis of charge states in the mixed valent ionic insulator AgO,"The doubly ionized $d^9$ copper ion provides, originally in La$_2$CuO$_4$ and
+later in many more compounds, the platform for high temperature
+superconductivity when it is forced toward higher levels of oxidation. The
+nearest chemical equivalent is Ag$^{2+}$, which is almost entirely avoided in
+nature. AgO is an illustrative example, being an unusual nonmagnetic insulating
+compound with an open $4d$ shell on one site. This compound has been
+interpreted in terms of one Ag$^{3+}$ ion at the fourfold site and one Ag$^{+}$
+ion that is twofold coordinated. We analyze more aspects of this compound,
+finding that indeed the Ag$^{3+}$ ion supports only four occupied $4d$-based
+Wannier functions per spin, while Ag$^+$ supports five, yet their physical
+charges are nearly equal. The oxygen $2p$ Wannier functions display two
+distinct types of behavior, one type of which includes conspicuous Ag $4d$
+tails. Calculation of the Born effective charge tensor shows that the mean
+effective charges of the Ag ions differ by about a factor of two, roughly
+consistent with the assigned formal charges. We analyze the $4d$ charge density
+and discuss it in terms of recent insights into charge states of insulating
+(and usually magnetic) transition metal oxides. What might be expected in
+electron- and hole-doped AgO is discussed briefly.",1409.6371v1
+2014-09-29,Convergence of quasiparticle self-consistent GW calculations of transition metal monoxides,"Finding an accurate ab initio approach for calculating the electronic
+properties of transition metal oxides has been a problem for several decades.
+In this paper, we investigate the electronic structure of the transition metal
+monoxides MnO, CoO, and NiO in their undistorted rock-salt structure within a
+fully iterated quasiparticle self-consistent GW (QPscGW) scheme. We study the
+convergence of the QPscGW method, i.e., how the quasiparticle energy
+eigenvalues and wavefunctions converge as a function of the QPscGW iterations,
+and we compare the converged outputs obtained from different starting
+wavefunctions. We find that the convergence is slow and that a one-shot
+G$_0$W$_0$ calculation does not significantly improve the initial eigenvalues
+and states. It is important to notice that in some cases the ""path"" to
+convergence may go through energy band reordering which cannot be captured by
+the simple initial unperturbed Hamiltonian. When we reach a fully iterated
+solution, the converged density of states, band-gaps and magnetic moments of
+these oxides are found to be only weakly dependent on the choice of the
+starting wavefunctions and in reasonably good agreement with the experiment.
+Finally, this approach provides a clear picture of the interplay between the
+various orbitals near the Fermi level of these simple transition metal
+monoxides. The results of these accurate {\it ab initio} calculations can
+provide input for models aiming at describing the low energy physics in these
+materials.",1409.8312v2
+2015-01-13,Weyl semimetal from spontaneous inversion symmetry breaking in pyrochlore oxides,"We study the electronic properties of strongly spin-orbit coupled electrons
+on the elastic pyrochlore lattice. Akin to the Peierls transition in
+one-dimensional systems, the coupling of the lattice to the electronic degrees
+of freedom can stabilize a spontaneous deformation of the crystal. This
+deformation corresponds to a breathing mode, which breaks the inversion
+symmetry. We find that for intermediate values of the staggered strain, the
+inversion-symmetry broken phase realizes a topological Weyl semimetal. In the
+temperature-elasticity phase diagram, the Weyl semimetal shows a reentrant
+phase behavior: it can be reached from a symmetric phase realized both at
+higher and at lower temperatures. The symmetric phase is a Dirac semimetal,
+which is protected by the non-symmorphic space group of the pyrochlore lattice.
+Beyond a critical value of the staggered strain, the symmetry-broken phase is a
+fully gapped trivial insulator. The surface states of the Weyl semimetal form
+open Fermi arcs and we observe that their connectivity depends on the
+termination of the crystal. In particular, for the $\{111\}$ films, the
+semiclassical closed electronic orbits of the surface states in a magnetic
+field cross the bulk either twice, four, six or twelve times. We demonstrate
+how one can tune the number of bulk crossings through a Lifshitz-like
+transition of the Fermi arcs, which we call Weyl-Lifshitz transition, by
+applying a surface potential. Our results offer a route to a topological Weyl
+semimetal in nonmagnetic materials and might be relevant for pyrochlore oxides
+with heavy transition-metal ions such as alloys of iridates.",1501.03029v1
+2015-02-27,Electrically Tunable Band Gap in Antiferromagnetic Mott Insulator Sr2IrO4,"The electronic band gap in conventional semiconductor materials, such as
+silicon, is fixed by the material's crystal structure and chemical composition.
+The gap defines the material's transport and optical properties and is of great
+importance for performance of semiconductor devices like diodes, transistors
+and lasers. The ability to tune its value would allow enhanced functionality
+and flexibility of future electronic and optical devices. Recently, an
+electrically tunable band gap was realized in a 2D material - electronically
+gated bilayer graphene [1-3]. Here we demonstrate the realization of an
+electrically tunable band gap in a 3D antiferromagnetic Mott insulator Sr2IrO4.
+Using nano-scale contacts between a sharpened Cu tip and a single crystal of
+Sr2IrO4, we apply a variable external electric field up to a few MV/m and
+demonstrate a continuous reduction in the band gap of Sr2IrO4 by as much as
+16%. We further demonstrate the feasibility of reversible resistive switching
+and electrically tunable anisotropic magnetoresistance,which provide evidence
+of correlations between electronic transport, magnetic order, and orbital
+states in this 5d oxide. Our findings suggest a promising path towards band gap
+engineering in 5d transition-metal oxides that could potentially lead to
+appealing technical solutions for next-generation electronic devices.",1502.07982v1
+2015-05-11,Impact of low-dose electron irradiation on n+p silicon strip sensors,"The response of n+p silicon strip sensors to electrons from a Sr-90 source
+was measured using a multi-channel read-out system with 25 ns sampling time.
+The measurements were performed over a period of several weeks, during which
+the operating conditions were varied. The sensors were fabricated by Hamamatsu
+Photonics K.K. on 200 micrometer thick float-zone and magnetic-Czochralski
+silicon. Their pitch was 80 micrometer, and both p-stop and p-spray isolation
+of the n+ strips were studied. The electrons from the Sr-90 source were
+collimated to a spot with a full-width-at-half-maximum of 2 mm at the sensor
+surface, and the dose rate in the SiO2 at the maximum was about 50 Gy/d.
+  After only a few hours of making measurements, significant changes in charge
+collection and charge sharing were observed. Annealing studies, with
+temperatures up to 80{\deg}C and annealing times of 18 hours, showed that the
+changes can only be partially annealed. The observations can be qualitatively
+explained by the increase of the positive oxide-charge density due to the
+ionization of the SiO2 by the radiation from the {\ss} source. TCAD simulations
+of the electric field in the sensor for different oxide-charge densities and
+different boundary conditions at the sensor surface support this explanation.
+  The relevance of the measurements for the design of p+n strip sensors is
+discussed.",1505.02672v1
+2015-04-29,"Comparative Study of Optical and Magneto-Optical Properties of Normal, Disordered and Inverse Spinel Type Oxides","Co$_3$O$_4$, ZnFe$_2$O$_4$, CoFe$_2$O$_4$, ZnCo$_2$O$_4$, and Fe$_3$O$_4$
+thin films were fabricated by pulsed laser deposition at high and low
+temperatures resulting in crystalline single-phase normal, inverse, as well as
+disordered spinel oxide thin films with smooth surface morphology. The
+dielectric function, determined by spectroscopic ellipsometry in a wide
+spectral range from 0.5 eV to 8.5 eV, is compared with the magneto-optical
+response of the dielectric tensor, investigated by magneto-optical Kerr effect
+(MOKE) spectroscopy in the spectral range from 1.7 eV to 5.5 eV with an applied
+magnetic field of 1.7 T. Crystal field, inter-valence and inter-sublattice
+charge transfer transitions, and transitions from O$_{2p}$ to metal cation 3d
+or 4s bands are identified in both the principal diagonal elements and the
+magneto-optically active off-diagonal elements of the dielectric tensor.
+Depending on the degree of cation disorder, resulting in local symmetry
+distortion, the magneto-optical response is found to be strongest for high
+crystal quality inverse spinels and for disordered normal spinel structure,
+contrary to the first principle studies of CoFe$_2$O$_4$ and ZnFe$_2$O$_4$. The
+results presented provide a basis for deeper understanding of light-matter
+interaction in this material system that is of vital importance for
+device-related phenomena and engineering.",1505.04664v3
+2015-07-05,Normal-state nodal electronic structure in underdoped high-Tc copper oxides,"An outstanding problem in the field of high-transition-temperature (high Tc)
+superconductivity is the identification of the normal state out of which
+superconductivity emerges in the mysterious underdoped regime. The normal state
+uncomplicated by thermal fluctuations is effectively accessed by the use of
+applied magnetic fields sufficiently strong to suppress long-range
+superconductivity at low temperatures. Proposals in which the normal ground
+state is characterised by small Fermi surface pockets that exist in the absence
+of symmetry breaking have been superseded by models based on the existence of a
+superlattice that breaks the translational symmetry of the underlying lattice.
+Recently, a charge superlattice model that positions a small electron-like
+Fermi pocket in the vicinity of the nodes (where the superconducting gap is
+minimum) has been proposed a replacement for the prevalent superlattice models
+that position the Fermi pocket in the vicinity of the pseudogap at the
+antinodes (where the superconducting gap is maximum). Although some ingredients
+of symmetry breaking have been recently revealed by crystallographic studies,
+their relevance to the electronic structure remains unresolved. Here we report
+angle-resolved quantum oscillation measurements in the underdoped copper oxide
+YBa2Cu3O6+x. These measurements reveal a normal ground state comprising
+electron-like Fermi surface pockets located in the vicinity of the
+superconducting gap minima (or nodes), and further point to an underlying
+superlattice structure of low frequency and long wavelength with features in
+common with the charge order identified recently by complementary spectroscopic
+techniques.",1507.01195v1
+2015-10-26,A close look at antiferromagnetism in multidimensional phase diagram of electron-doped copper oxide,"Emergency of superconductivity at the instabilities of antiferromagnetism
+(AFM), spin/charge density waves has been widely recognized in unconventional
+superconductors. In copper-oxide superconductors, spin fluctuations play a
+predominant role in electron pairing with electron dopants yet composite orders
+veil the nature of superconductivity for hole-doped family. However, in
+electron-doped ones the ending point of AFM is still in controversy for
+different probes or its sensitivity to oxygen content. Here, by carefully
+tuning the oxygen content, a systematic study of Hall signal and
+magnetoresistivity up to 58 Tesla on optimally doped La2-xCexCuO4+-{\delta} (x
+= 0.10) thin films identifies two characteristic temperatures at 62.5+-7.5 K
+and 25+-5 K. The former is quite robust whereas the latter becomes flexible
+with increasing magnetic field, thereby linked to two- and three-dimensional
+AFM, evident from the multidimensional phase diagram as a function of oxygen as
+well as Ce dopants. Consequently, the observation of extended AFM phase in
+contrast to {\mu}SR probe corroborates an elevated critical doping in field,
+providing an unambiguous picture to understand the interactions between AFM and
+superconductivity.",1510.07388v1
+2016-03-24,Unconventional Magnetism and Band Gap Formation in LiFePO4: Consequence of Polyanion Induced Non-planarity,"Oxygen plays a critical role in strongly correlated transition metal oxides
+as crystal field effect is one of the key factors that determine the degree of
+localization of the valence d/f states. Based on the localization, a set of
+conventional mechanisms such as Mott-Hubbard, Charge-transfer and Slater were
+formulated to explain the antiferromagnetic and insulating (AFI) phenomena in
+many of these correlated systems. From the case study on LiFePO4, through
+density-functional calculations, we demonstrate that none of these mechanisms
+are strictly applicable to explain the AFI behavior when the transition metal
+oxides have polyanions such as (PO4)3-. The symmetry-lowering of the
+metal-oxygen complex, to stabilize the polyanion, creates an asymmetric crystal
+field for d/f states. In LiFePO4 this field creates completely non-degenerate
+Fe-d states which, with negligible p-d and d-d covalent interactions, become
+atomically localized to ensure a gap at the Fermi level. Due to large exchange
+splitting, high spin state is favored and an antiferromagnetic configuration is
+stabilized. For the prototype LiFePO4, independent electron approximation is
+good enough to obtain the AFI ground state. Inclusion of additional correlation
+measures like Hubbard U simply amplifies the gap and therefore LiFePO4 can be
+preferably called as weakly coupled Mott insulator.",1603.08403v1
+2017-02-19,Correlative cellular ptychography with functionalized nanoparticles at the Fe L-edge,"Precise localization of nanoparticles within a cell is crucial to the
+understanding of cell-particle interactions and has broad applications in
+nanomedicine. Here, we report a proof-of-principle experiment for imaging
+individual functionalized nanoparticles within a mammalian cell by correlative
+microscopy. Using a chemically-fixed, HeLa cell labeled with fluorescent
+core-shell nanoparticles as a model system, we implemented a graphene-oxide
+layer as a substrate to significantly reduce background scattering. We
+identified cellular features of interest by fluorescence microscopy, followed
+by scanning transmission X-ray tomography to localize the particles in 3D, and
+ptychographic coherent diffractive imaging of the fine features in the region
+at high resolution. By tuning the X-ray energy to the Fe L-edge, we
+demonstrated sensitive detection of nanoparticles composed of a 22 nm magnetic
+Fe3O4 core encased by a 25-nm-thick fluorescent silica (SiO2) shell. These
+fluorescent core-shell nanoparticles act as landmarks and offer clarity in a
+cellular context. Our correlative microscopy results confirmed a subset of
+particles to be fully internalized, and high-contrast ptychographic images
+showed two oxidation states of individual nanoparticles with a resolution of
+~16.5 nm. The ability to precisely localize individual fluorescent
+nanoparticles within mammalian cells will expand our understanding of the
+structure/function relationships for functionalized nanoparticles.",1702.05680v1
+2017-08-06,Electrical transport and optical band gap of NiFe$_\textrm{2}$O$_\textrm{x}$ thin films,"We fabricated NiFe$_\textrm{2}$O$_\textrm{x}$ thin films on
+MgAl$_2$O$_4$(001) substrates by reactive dc magnetron co-sputtering varying
+the oxygen partial pressure during deposition. The fabrication of a variable
+material with oxygen deficiency leads to controllable electrical and optical
+properties which would be beneficial for the investigations of the transport
+phenomena and would, therefore, promote the use of such materials in spintronic
+and spin caloritronic applications. We used several characterization techniques
+in order to investigate the film properties, focusing on their structural,
+magnetic, electrical, and optical properties. From the electrical resistivity
+measurements we obtained the conduction mechanisms that govern the systems in
+high and low temperature regimes, extracting low thermal activation energies
+which unveil extrinsic transport mechanisms. The thermal activation energy
+decreases in the less oxidized samples revealing the pronounced contribution of
+a large amount of electronic states localized in the band gap to the electrical
+conductivity. Hall effect measurements showed the mixed-type semiconducting
+character of our films. The optical band gaps were determined via
+ultraviolet-visible spectroscopy. They follow a similar trend as the thermal
+activation energy, with lower band gap values in the less oxidized samples.",1708.01937v1
+2018-04-07,Bare and Polymer Coated Iron Oxide Superparamagnetic Nanoparticles for Effective Removal of U (VI) from Acidic and Neutral Aqueous Medium,"Superparamagnetic {\gamma}-Fe2O3 nanoparticles (5 nm diameter) were
+synthesized in water. The bare particles exhibit good colloidal stability at ~
+pH 2 because of the strong electrostatic repulsion with a surface charge of +25
+mV. The polyacrylic acid (PAA)-coated particles exhibit remarkable colloidal
+stability at ~ pH 7 with abundant free carboxyl groups as reactive sites for
+subsequent functionalization. In this work, we used zeta potential analysis,
+transmission electron microscopy, small angle X-ray scattering, and Inductively
+coupled plasma mass spectrometry to investigate the adsorption behavior of U
+(VI) on bare and coated colloidal superparamagnetic nanoparticles at pH 2 and
+pH 7. At pH 2, uranyl ion (UO22+) absorbed on the surface of the bare particles
+with decreasing particle surface charge. This induced particle agglomeration.
+At pH 7, uranyl ion (UO22+) hydrolyzed and formed plate-like particles of
+uranium hydroxide that were ~ 50 nm in diameter. The PAA-coated iron oxide
+nanoparticles absorbed on the surface of these U (VI) hydroxide plates to form
+large aggregates that precipitate to the bottom of the dispersion. At both pH 2
+and pH 7, the resulting U (VI)/nanoparticle complex can be easily collected and
+extracted from the aqueous environment via an external magnetic field. The
+results show that both bare and polymer-coated superparamagnetic {\gamma}-Fe2O3
+nanoparticles are potential absorbents for removing U (VI) from water.",1804.02522v1
+2013-08-26,Superconductivity in Ba1-xKxTi2Sb2O (0 < x < 1) controlled by charge doping,"The solid solution of antimonide-oxides Ba1-xKxTi2Sb2O (0 < x < 1) has been
+synthesized by solid-state reactions and characterized by X-ray powder
+diffraction (CeCr2Si2C-type structure; P4/mmm, Z = 1). The crystal structure
+consists of Ti2Sb2O-layers that are stacked with layers of barium atoms along
+the c-axis. BaTi2Sb2O is a known superconductor with a critical temperature
+(Tc) of 1.2 K. Substitution of barium through potassium raises Tc up to 6.1 K
+at 12 % potassium, while no superconductivity emerges with concentrations
+higher than 20 %. Anomalies in electrical transport and magnetic susceptibility
+indicate charge density wave (CDW) instabilities. The CDW transition
+temperatures (Ta) decrease from 50 K in the parent compound to 28 K at 10 %
+potassium substitution. No CDW transition was detected at higher
+concentrations, and no evidence for a reduction of the lattice symmetry below
+Ta was found. The lattice parameters vary linearly while the unit cell volume
+increases with higher potassium concentrations. The phase diagrams Tc(x) and
+Ta(x) of Ba1-xKxTi2Sb2O are remarkably similar to the known series
+Ba1-xNaxTi2Sb2O (0 < x < 0.33) in spite of the reverse volume effect. From this
+we conclude that the charge and not the volume determines the phase diagrams of
+these superconducting antimony oxides.",1308.5660v1
+2017-04-06,Towards Picogram Detection of Superparamagnetic Iron-Oxide Particles Using a Gradiometric Receive Coil,"Superparamagnetic iron-oxide nanoparticles can be used in a variety of
+medical applications like vascular or targeted imaging. Magnetic particle
+imaging (MPI) is a promising tomographic imaging technique that allows
+visualizing the 3D nanoparticle distribution concentration in a non-invasive
+manner. The two main strengths of MPI are high temporal resolution and high
+sensitivity. While the first has been proven in the assessment of dynamic
+processes like cardiac imaging, it is unknown how far the detection limit of
+MPI can be lowered. Within this work, we will present a highly sensitive
+gradiometric receive-coil unit combined with a noise-matching network tailored
+for the measurement of mice. The setup is capable of detecting 5 ng of iron in
+vitro at 2.14 sec acquisition time. In terms of iron concentration we are able
+to detect 156 {\mu}g/L marking the lowest value that has been reported for an
+MPI scanner so far. In vivo MPI mouse images of a 512 ng bolus at 21.5 ms
+acquisition time allow for capturing the flow of an intravenously injected
+tracer through the heart of a mouse. Since it has been rather difficult to
+compare detection limits across MPI publications we propose guidelines
+improving the comparability of future MPI studies.",1704.01789v2
+2012-01-14,Effect of lattice geometry on magnon Hall effect in ferromagnetic insulators,"We have investigated the thermal Hall effect of magnons for various
+ferromagnetic insulators. For pyrochlore ferromagnetic insulators
+Lu$_2$V$_2$O$_7$, Ho$_2$V$_2$O$_7$, and In$_2$Mn$_2$O$_7$, finite thermal Hall
+conductivities have been observed below the Curie temperature $T_C$ . From the
+temperature and magnetic field dependences, it is concluded that magnons are
+responsible for the thermal Hall effect. The Hall effect of magnons can be well
+explained by the theory based on the Berry curvature in momentum space induced
+by the Dzyaloshinskii-Moriya (DM) interaction. The analysis has been extended
+to the transition metal (TM) oxides with perovskite structure. The thermal Hall
+signal was absent or far smaller in La$_2$NiMnO$_6$ and YTiO$_3$, which have
+the distorted perovskite structure with four TM ions in the unit cell. On the
+other hand, a finite thermal Hall response is discernible below $T_C$ in
+another ferromagentic perovskite oxide BiMnO$_3$, which shows orbital ordering
+with a larger unit cell. The presence or absence of the thermal Hall effect in
+insulating pyrochlore and perovskite systems reflect the geometric and
+topological aspect of DM-induced magnon Hall effect.",1201.3002v2
+2016-12-13,Multiple supersonic phase fronts launched at a complex-oxide hetero-interface,"Selective optical excitation of a substrate lattice can drive phase changes
+across hetero-interfaces. This phenomenon is a non-equilibrium analogue of
+static strain control in heterostructures and may lead to new applications in
+optically controlled phase change devices. Here, we make use of time-resolved
+non-resonant and resonant x-ray diffraction to clarify the underlying physics,
+and to separate different microscopic degrees of freedom in space and time. We
+measure the dynamics of the lattice and that of the charge disproportionation
+in NdNiO3, when an insulator-metal transition is driven by coherent lattice
+distortions in the LaAlO3 substrate. We find that charge redistribution
+propagates at supersonic speeds from the interface into the NdNiO3 film,
+followed by a sonic lattice wave. When combined with measurements of magnetic
+disordering and of the metal-insulator transition, these results establish a
+hierarchy of events for ultrafast control at complex oxide hetero-interfaces.",1612.04089v1
+2018-01-16,Atmospheric Beacons of Life from Exoplanets Around G and K Stars,"The current explosion in detection and characterization of thousands of
+extrasolar planets from the Kepler mission, the Hubble Space Telescope, and
+large ground-based telescopes opens a new era in searches for Earth-analog
+exoplanets with conditions suitable for sustaining life. As more Earth-sized
+exoplanets are detected in the near future, we will soon have an opportunity to
+identify habitable worlds. Which atmospheric biosignature gases from habitable
+planets can be detected with our current capabilities? The detection of the
+common biosignatures from nitrogen-oxygen rich terrestrial-type exoplanets
+including molecular oxygen (O2), ozone (O3), water vapor (H2O), carbon dioxide
+(CO2), nitrous oxide (N2O), and methane (CH4) requires days of integration time
+with largest space telescopes, and thus are very challenging for current
+instruments. In this paper we propose to use the powerful emission from
+rotational-vibrational bands of nitric oxide, hydroxyl and molecular oxygen as
+signatures of nitrogen, oxygen, and water rich atmospheres of terrestrial type
+exoplanets highlighted by the magnetic activity from young G and K
+main-sequence stars. The signals from these fundamental chemical prerequisites
+of life we call atmospheric beacons of life create a unique opportunity to
+perform direct imaging observations of Earth-sized exoplanets with high
+signal-to-noise and low spectral resolution with the upcoming NASA missions.",1801.05341v1
+2018-09-07,Infinite-randomness fixed point of the quantum superconductor-metal transitions in amorphous thin films,"The magnetic-field-tuned quantum superconductor-insulator transitions of
+disordered amorphous indium oxide films are a paradigm in the study of quantum
+phase transitions, and exhibit power-law scaling behavior. For superconducting
+indium oxide films with low disorder, such as the ones reported on here, the
+high-field state appears to be a quantum-corrected metal. Resistance data
+across the superconductor-metal transition in these films are shown here to
+obey an activated scaling form appropriate to a quantum phase transition
+controlled by an infinite randomness fixed point in the universality class of
+the random transverse-field Ising model. Collapse of the field-dependent
+resistance vs. temperature data is obtained using an activated scaling form
+appropriate to this universality class, using values determined through a
+modified form of power-law scaling analysis. This exotic behavior of films
+exhibiting a superconductor-metal transition is caused by the dissipative
+dynamics of superconducting rare regions immersed in a metallic matrix, as
+predicted by a recent renormalization group theory. The smeared crossing points
+of isotherms observed are due to corrections to scaling which are expected near
+an infinite randomness critical point, where the inverse disorder strength acts
+as an irrelevant scaling variable.",1809.02672v3
+2018-09-12,Probing Quantum Confinement and Electronic Structure at Polar Oxide Interfaces,"Polar discontinuities occurring at interfaces between two different materials
+constitute both a challenge and an opportunity in the study and application of
+a variety of devices. In order to cure the large electric field occurring in
+such structures, a reconfiguration of the charge landscape sets in at the
+interface via chemical modifications, adsorbates or charge transfer. In the
+latter case, one may expect a local electronic doping of one material: one
+sparkling example is the two-dimensional electron liquid (2DEL) appearing in
+SrTiO$_3$ once covered by a polar LaAlO$_3$ layer. Here we show that tuning the
+formal polarisation of a (La,Al)$_{1-x}$(Sr,Ti)$_x$O$_3$ (LASTO:$x$) overlayer
+through chemical composition modifies the quantum confinement of the 2DEL in
+SrTiO$_3$ and its electronic band structure. The analysis of the behaviour in
+magnetic field of superconducting field-effect devices reveals, in agreement
+with $ab\ initio$ calculations and self-consistent Poisson-Schr\""odinger
+modelling, that quantum confinement and energy splitting between electronic
+bands of different symmetries strongly depend on interface charge densities.
+These results not only strongly support the polar discontinuity mechanisms with
+a full charge transfer to explain the origin of the 2DEL at the celebrated
+LaAlO$_3$/SrTiO$_3$ interface, but also demonstrate an effective tool for
+tailoring the electronic structure at oxide interfaces.",1809.04246v1
+2019-06-24,Conductivity of Dirac-like surface states in correlated honeycomb transition metal oxide Mott insulators,"The search for materials with novel and unusual electronic properties is at
+the heart of condensed matter physics as well as the basis to develop
+conceptual new technologies. In this context, the correlated honeycomb
+transition metal oxides attract large attention for both, being a possible
+experimental realization of the theoretically predicted magnetic Kitaev
+exchange and the theoretical prospect of topological nontriviality. The Mott
+insulating sodium iridate is prototypical among these materials with the
+promising prospect to bridge the field of strongly correlated systems with
+topology, finally opening a path to a wide band gap material with exotic
+surface properties. Here, we report a profound study of the electronic
+properties of ultra-high-vacuum cleaved surfaces combining transport
+measurements with scanning tunneling techniques, showing that multiple
+conductive channels with differing nature are simultaneously apparent in this
+material. Most importantly, a V-shaped density of states and a low sheet
+resistance, in spite of a large defect concentration, point towards a
+topologically protected surface conductivity contribution. By incorporating the
+issue of the addressability of electronic states in the tunneling process, we
+develop a framework connecting previous experimental results as well as
+theoretical considerations.",1906.09809v2
+2020-04-06,Unexpected crystalline homogeneity from the disordered bond network in La(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 films,"Designing and understanding functional electronic and magnetic properties in
+perovskite oxides requires controlling and tuning the underlying crystal
+lattice. Here we report the structure, including oxygen and cation positions,
+of a single-crystal, entropy stabilized perovskite oxide film of
+La(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 grown on SrTiO3 (001). The parent materials
+range from orthorhombic (LaCrO3, LaMnO3 and LaFeO3) to rhombohedral (LaCoO3 and
+LaNiO3), and first principles calculations indicate that these structural
+motifs are nearly degenerate in energy and should be highly distorted
+site-to-site. Despite this extraordinary local configurational disorder on the
+B-site sublattice, we find a structure with unexpected macroscopic crystalline
+homogeneity with a clear orthorhombic unit cell, whose orientation is
+demonstrated to be controlled by the strain and crystal structure of the
+substrate for films grown on (La0.3Sr0.7)(Al0.65Ta0.35)O3 (LSAT) and NdGaO3
+(110). Furthermore, quantification of the atom positions within the unit cell
+reveal that the orthorhombic distortions are small, close to LaCrO3, which may
+be driven by a combination of disorder averaging and the average ionic radii.
+This is the first step towards understanding the rules for designing new
+crystal motifs and tuning functional properties through controlled
+configurational complexity.",2004.02985v1
+2020-12-14,Universal quantum transition from superconducting to insulating states in pressurized Bi2Sr2CaCu2O8+δ superconductors,"Copper oxide superconductors have continually fascinated the communities of
+condensed matter physics and material sciences because they host the highest
+ambient-pressure superconducting transition temperature (Tc) and mysterious
+physics. Searching for the universal correlation between the superconducting
+state and its normal state or neighboring ground state is believed to be an
+effective way for finding clues to elucidate the underlying mechanism of the
+superconductivity. One of the common pictures for the copper oxide
+superconductors is that a well-behaved metallic phase will present after the
+superconductivity is entirely suppressed by chemical doping or application of
+the magnetic field. Here, we report a different observation of universal
+quantum transition from superconducting state to insulating-like state under
+pressure in the under-, optimally- and over-doped Bi2212 superconductors with
+two CuO2 planes in a unit cell. The same phenomenon has been also found in the
+Bi2201 superconductor with one CuO2 plane and the Bi2223 superconductor with
+three CuO2 planes in a unit cell. These results not only provide fresh
+information but also pose a new challenge for achieving a unified understanding
+on the underlying physics of the high-Tc superconductivity.",2012.07523v3
+2017-05-07,Antiferromagnetic correlations in the metallic strongly correlated transition metal oxide LaNiO$_3$,"The material class of rare earth nickelates with high Ni$^{3+}$ oxidation
+state is generating continued interest due to the occurrence of a
+metal-insulator transition with charge order and the appearance of
+non-collinear magnetic phases within this insulating regime. The recent
+theoretical prediction for superconductivity in LaNiO$_3$ thin films has also
+triggered intensive research efforts. LaNiO$_3$ seems to be the only rare earth
+nickelate that stays metallic and paramagnetic down to lowest temperatures. So
+far, centimetre-sized impurity-free single crystal growth has not been reported
+for the rare earth nickelates material class since elevated oxygen pressures
+are required for their synthesis. Here, we report on the successful growth of
+centimetre-sized LaNiO$_3$ single crystals by the floating zone technique at
+oxygen pressures of up to 150 bar. Our crystals are essentially free from
+Ni$^{2+}$ impurities and exhibit metallic properties together with an
+unexpected but clear antiferromagnetic transition.",1705.02589v2
+2017-11-27,"Emergent odd-parity multipoles and magnetoelectric effects on a diamond structure: implication to 5$d$ transition metal oxides $A$OsO$_4$ ($A=$ K, Rb, and Cs)","We report our theoretical predictions on the linear magnetoelectric (ME)
+effects originating from odd-parity multipoles associated with spontaneous spin
+and orbital ordering on a diamond structure. We derive a two-orbital model for
+$d$ electrons in $e_g$ orbitals by including the effective spin-orbit coupling
+which arises from the mixing between $e_g$ and $t_{2g}$ orbitals. We show that
+the model acquires a net antisymmetric spin-orbit coupling once staggered spin
+and orbital orders occur spontaneously. The staggered orders are accompanied by
+odd-parity multipoles: magnetic monopole, quadrupoles, and toroidal dipoles. We
+classify the types of the odd-parity multipoles according to the symmetry of
+the spin and orbital orders. Furthermore, by computing the ME tensor using the
+linear response theory, we show that the staggered orders induce a variety of
+the linear ME responses. We elaborate all possible ME responses for each
+staggered order, which are useful to identify the order parameter and to detect
+the odd-parity multipoles by measuring the ME effects. We also elucidate the
+effect of lowering symmetry by a tetragonal distortion, which leads to richer
+ME responses. The implications of our results are discussed for $5d$ transition
+metal oxides, $A$OsO$_4$ ($A=$ K, Rb, and Cs), in which the order parameters
+are not fully identified.",1711.09507v1
+2018-06-04,Towards a systematically improvable many-body description of antiferromagnetic iron oxide,"We report variational and fixed-node diffusion quantum Monte Carlo (QMC)
+calculations of anti-ferromagnetic iron oxide (FeO) in the ground state B1
+crystal structure. The goal of this study was a systematic investigation of the
+sensitivity of several ground state properties to a variety of QMC wave
+function generation techniques including advanced wave functions such as
+multi-determinant expansions and backflow transformations. We found that the
+predicted lattice distortion was largely controlled by the choice of single
+particle orbitals used to construct the wave function, rather than by
+subsequent wave function optimization techniques within QMC. However, the
+absolute magnetic moment was remarkably insensitive to the method of wave
+function construction. QMC estimates of total spin density indicate that in
+addition to strong electronic correlation of the Fe $3d$ states, charge
+transfer may be an important but challenging piece of physics to accurately
+capture within existing QMC methods. Finally, we highlight the need for
+advanced and systematically improvable many-body wave functions suitable for
+accurately describing challenging real systems.",1806.01383v2
+2019-01-12,Probing single unit-cell resolved electronic structure modulations in oxide superlattices with standing-wave photoemission,"Control of structural couplings at the complex-oxide interfaces is a powerful
+platform for creating new ultrathin layers with electronic and magnetic
+properties unattainable in the bulk. However, with the capability to design and
+control the electronic structure of such buried layers and interfaces at a
+unit-cell level, a new challenge emerges to be able to probe these engineered
+emergent phenomena with depth-dependent atomic resolution as well as element-
+and orbital selectivity. Here, we utilize a combination of core-level and
+valence-band soft x-ray standing-wave photoemission spectroscopy, in
+conjunction with scanning transmission electron microscopy, to probe the
+depth-dependent and single-unit-cell resolved electronic structure of an
+isovalent manganite superlattice [Eu0.7Sr0.3MnO3/La0.7Sr0.3MnO3]x15 wherein the
+electronic-structural properties are intentionally modulated with depth via
+engineered oxygen octahedra rotations/tilts and A-site displacements. Our
+unit-cell resolved measurements reveal significant transformations in the local
+chemical and electronic valence-band states, which are consistent with the
+layer-resolved first-principles theoretical calculations, thus opening the door
+for future depth-resolved studies of a wide variety of hetero-engineered
+material systems.",1901.03778v1
+2019-04-26,"Spin, orbital and topological order in models of strongly correlated electrons","Different types of order are discussed in the context of strongly correlated
+transition metal oxides, involving pure compounds and $3d^{3}-4d^{4}$ and
+$3d^{2}-4d^{4}$ hybrids. Apart from standard, long-range spin and orbital
+orders we observe also exotic non-colinear spin patterns. Such patters can
+arise in presence of atomic spin-orbit coupling, which is a typical case, or
+due to spin-orbital entanglement at the bonds in its absence, being much less
+trivial. Within a special interacting one-dimensional spin-orbital model it is
+also possible to find a rigorous topological magnetic order in a gapless phase
+that goes beyond any classification tables of topological states of matter.
+This is an exotic example of a strongly correlated topological state. Finally,
+in the less correlated limit of $4d^{4}$ oxides, when orbital selective Mott
+localization can occur it is possible to stabilize by a $3d^{3}$ doping
+one-dimensional zigzag antiferromagnetic phases. Such phases have exhibit
+nonsymmorphic spatial symmetries that can lead to various topological
+phenomena, like single and mutliple Dirac points that can turn into nodal rings
+or multiple topological charges protecting single Dirac points. Finally, by
+creating a one-dimensional $3d^{2}-4d^{4}$ hybrid system that involves orbital
+pairing terms, it is possible to obtain an insulating spin-orbital model where
+the orbital part after fermionization maps to a non-uniform Kitaev model. Such
+model is proved to have topological phases in a wide parameter range even in
+the case of completely disordered $3d^{2}$ impurities. What more, it exhibits
+hidden Lorentz-like symmetries of the topological phase, that live in the
+parameters space of the model.",1904.11772v1
+2019-11-18,Bivalent nature of Fe and W ions in the antiferromagnetic Sr2FeWO6 material produced by the combustion technique,"The synthesis of the double perovskite Sr2FeWO6 through the direct combustion
+technique is reported. A complete characterization of the crystalline structure
+is performed from Synchrotron X-ray measurements and subsequent Rietveld
+analysis. The results evidence that this material crystallizes in a monoclinic
+structure, P21/n space group, with strong distortions in the Fe-O6 and W-O6
+octahedra, which is consistent with Glazer's notation a-b+a-. A superficial
+morphological study through scanning electron microscopy images reveals that
+this synthesis technique allows obtaining nanometric grains with 160 nm mean
+size. The semiquantitative compositional analysis through spectroscopy of X-ray
+energy dispersion by electrons shows that the produced material does not
+contain other chemical elements besides those expected form the stoichiometric
+formula. Results of analyzes of spectroscopy of photoelectrons emitted by
+X-rays suggest that there is 66.9% of the material with oxidation states Fe2+
+and W6+ and 33.1% with oxidation states Fe3+ and W5+. This bivalence of Fe and
+W cations is corroborated by means the M\""ossbauer spectroscopy technique.
+Finally, the magnetic response in AC susceptibility curves allows us to affirm
+that at low temperatures the material adopts an antiferromagnetic behavior with
+TN=32 K, with a tendency to the ferromagnetic state above T=150 K mostly due to
+the presence of Fe3+ ions in the high spin configuration 3d5, S = 5/2.",1911.07610v1
+2020-06-26,Propagation control of octahedral tilt in SrRuO3 via artificial heterostructuring,"Bonding geometry engineering of metal-oxygen octahedra is a facile way of
+tailoring various functional properties of transition metal oxides. Several
+approaches, including epitaxial strain, thickness, and stoichiometry control,
+have been proposed to efficiently tune the rotation and tilting of the
+octahedra, but these approaches are inevitably accompanied by unnecessary
+structural modifications such as changes in thin-film lattice parameters. In
+this study, we propose a method to selectively engineer the octahedral bonding
+geometries, while maintaining other parameters that might implicitly influence
+the functional properties. A concept of octahedral tilt propagation engineering
+has been developed using atomically designed SrRuO3/SrTiO3 superlattices. In
+particular, the propagation of RuO6 octahedral tilting within the SrRuO3 layers
+having identical thicknesses was systematically controlled by varying the
+thickness of adjacent SrTiO3 layers. This led to a substantial modification in
+the electromagnetic properties of the SrRuO3 layer, significantly enhancing the
+magnetic moment of Ru. Our approach provides a method to selectively manipulate
+the bonding geometry of strongly correlated oxides, thereby enabling a better
+understanding and greater controllability of their functional properties.",2006.14740v1
+2020-09-17,Probing the Meta-Stability of Oxide Core/Shell Nanoparticle Systems at Atomic Resolution,"Hybrid nanoparticles allow exploiting the interplay of confinement, proximity
+between different materials and interfacial effects. However, to harness their
+properties an in-depth understanding of their (meta)stability and interfacial
+characteristics is crucial. This is especially the case of nanosystems based on
+functional oxides working under reducing conditions, which may severely impact
+their properties. In this work, the in-situ electron-induced selective
+reduction of Mn3O4 to MnO is studied in magnetic Fe3O4/Mn3O4 and Mn3O4/Fe3O4
+core/shell nanoparticles by means of high-resolution scanning transmission
+electron microscopy combined with electron energy-loss spectroscopy. Such
+in-situ transformation allows mimicking the actual processes in operando
+environments. A multi-stage image analysis using geometric phase analysis
+combined with particle image velocity enables direct monitoring of the
+relationship between structure, chemical composition and strain relaxation
+during the Mn3O4 reduction. In the case of Fe3O4/Mn3O4 core/shell the
+transformation occurs smoothly without the formation of defects. However, for
+the inverse Mn3O4/Fe3O4 core/shell configuration the electron beam-induced
+transformation occurs in different stages that include redox reactions and void
+formation followed by strain field relaxation via formation of defects. This
+study highlights the relevance of understanding the local dynamics responsible
+for changes in the particle composition in order to control stability and,
+ultimately, macroscopic functionality.",2009.08133v1
+2021-04-21,Establishing quasi-linear quadrupole functional topology by oxygen-vacancy engineering at a ferroelectric domain wall,"Oxygen vacancies in two-dimensional metal-oxide structures garner much
+attention due to unique conductive, magnetic and even superconductive
+functionalities they induce. Ferroelectric domain walls have been a prominent
+recent example because they serve as a hub for topological defects that enable
+unusual symmetries and are relevant for low-energy switching technologies.
+However, owing to the light weight of oxygen atoms and localized effects of
+their vacancies, the atomic-scale electrical and mechanical influence of oxygen
+vacancies has remained elusive. Here, stable individual oxygen vacancies were
+found and engineered in situ at domain walls of seminal titanate perovskite
+ferroics. The atomic-scale strain, electric-field, charge and dipole-moment
+distribution around these vacancies were characterized by combining advanced
+transmission electron microscopy and first-principle methodologies. 3-5 %
+tensile strain was observed at the immediate surrounding unit cells of the
+vacancies. The dipole-moment distribution around the vacancy was found to be an
+alternating head-to-head $-$ tail-to-tail $-$ head-to-head structure, giving
+rise to a quasi-linear quadrupole topology. Reduction of the nearby Ti ion as
+well as enhanced charging and electric-field concentration near the vacancy
+confirmed the quadrupole structure and illustrated its local effects on the
+electrical and structural properties. Significant intra-band states were found
+in the unit cell of the vacancies, proposing a meaningful domain-wall
+conductivity. Oxygen-vacancy engineering and controllable quadrupoles that
+enable pre-determining both atomic-scale and global functional properties offer
+a promising platform of electro-mechanical topological solitons and device
+miniaturization in metal oxides.",2104.10445v1
+2021-06-22,Intrinsic versus extrinsic orbital and electronic reconstructions at complex oxide interfaces,"The interface between the insulators LaAlO$_3$ and SrTiO$_3$ accommodates a
+two-dimensional electron liquid (2DEL) -- a high mobility electron system
+exhibiting superconductivity as well as indications of magnetism and
+correlations. While this flagship oxide heterostructure shows promise for
+electronics applications, the origin and microscopic properties of the 2DEL
+remain unclear. The uncertainty remains in part because the electronic
+structures of such nanoscale buried interfaces are difficult to probe, and is
+compounded by the variable presence of oxygen vacancies and coexistence of both
+localized and delocalized charges. These various complications have precluded
+decisive tests of intrinsic electronic and orbital reconstruction at this
+interface. Here we overcome prior difficulties by developing an interface
+analysis based on the inherently interface-sensitive resonant x-ray
+reflectometry. We discover a high charge density of 0.5 electrons per
+interfacial unit cell for samples above the critical LaAlO$_3$ thickness, and
+extract the depth dependence of both the orbital and electronic reconstructions
+near the buried interface. We find that the majority of the reconstruction
+phenomena are confined to within 2 unit cells of the interface, and we quantify
+how oxygen vacancies significantly affect the electronic system. Our results
+provide strong support for the existence of polarity induced electronic
+reconstruction, clearly separating its effects from those of oxygen vacancies.",2106.12061v1
+2021-10-04,Data-driven quest for two-dimensional non-van der Waals materials,"Two-dimensional (2D) materials are frequently associated with the sheets
+which form bulk layered compounds bonded by van der Waals (vdW) forces. The
+anisotropy and weak interaction between the sheets have also been the main
+criteria in the computational search for new 2D systems, which predicted about
+2000 exfoliable compounds. However, several representatives of a new type of
+non-vdW 2D systems, such as hematene or ilmenene, which have no layered 3D
+analogues, and which, unlike, e.g. silicene, do not need to strongly interact
+with the substrate to be stable, were recently manufactured. The family of
+non-vdW 2D materials is an attractive playground for data-driven
+high-throughput approaches as computational design principles are still
+missing. Here, we outline a new set of 8 binary and 20 ternary candidates by
+filtering the AFLOW-ICSD database according to the structural prototype of the
+first two template systems realized in experiment. All materials show a strong
+structural relaxation upon confinement to 2D which is essential to correctly
+estimate the bonding strength between facets. The oxidation state of the
+cations at the surface of the sheets is demonstrated to regulate the
+inter-facet binding energy with low oxidation states leading to weak bonding.
+We anticipate this descriptor to be highly useful to obtain novel 2D materials,
+providing clear guidelines for experiments. Our calculations further indicate
+that the materials exhibit a vast range of appealing electronic, optical and
+magnetic properties, which is expected to also make them attractive for
+potential applications particularly in spintronics.",2110.01366v1
+2021-12-06,CaCu$_3$Ru$_4$O$_{12}$: a high Kondo-temperature transition metal oxide,"We present a comprehensive study of CaCu$_3$Ru$_4$O$_{12}$ using bulk
+sensitive hard and soft x-ray spectroscopy combined with local-density
+approximation (LDA) + dynamical mean-field theory (DMFT) calculations.
+Correlation effects on both the Cu and Ru ions can be observed. From the Cu
+$2p$ core level spectra we deduce the presence of magnetic Cu$^{2+}$ ions
+hybridized with a reservoir of itinerant electrons. The strong photon energy
+dependence of the valence band allows us to disentangle the Ru, Cu, and O
+contributions and thus to optimize the DMFT calculations. The calculated spin
+and charge susceptibilities show that the transition metal oxide
+CaCu$_3$Ru$_4$O$_{12}$ must be classified as a Kondo system and that the Kondo
+temperature is in the range of 500-1000 K.",2112.02898v1
+2022-01-20,Stabilization of CeGe$_3$ with Ti and O featuring tetravalent Ce ions: (Ce$_{0.85}$Ti$_{0.15}$)Ge$_3$O$_{0.5}$,"Sub-oxides with the anti-perovskite structure constitute a large part of the
+interstitial stabilized compounds with novel chemical and physical properties,
+especially in the systems containing rare earth elements and/or early
+transition metal elements. A new sub-oxide compound,
+(Ce$_{0.85}$Ti$_{0.15}$)Ge$_3$O$_{0.5}$, is synthesized by flux growth. The
+compound crystallizes in a cubic structure which can be considered as an
+ordered vacancy variant of anti-perovskite-structure or an ordered interstitial
+variant of the Cu$_3$Au type, with a space group of Fm-3m (225). The structure
+is refined from X-ray single crystal methods. The compound may be considered as
+a compound stabilized by chemical pressure generated by the substitution and
+the interstitials atoms. The stability of the compounds in RTr$_3$ systems (R =
+rare earth elements except Pm and Sc, Tr = tetrel elements such as Si, Ge, Sn,
+Pb) seem to be highly correlated to the ratio of the rare earth elements' radii
+to the main group elements' atomic radii. The magnetic property of the compound
+confirms the 4$^+$ valence of the Ce atoms. The resistivity measurement of the
+compound shows that it is metallic.",2201.08449v1
+2022-02-02,Stabilization of three-dimensional charge order through interplanar orbital hybridization in Pr$_x$Y$_{1-x}$Ba$_2$Cu$_3$O$_{6+δ}$,"The shape of 3$d$-orbitals often governs the electronic and magnetic
+properties of correlated transition metal oxides. In the superconducting
+cuprates, the planar confinement of the $d_{x^2-y^2}$ orbital dictates the
+two-dimensional nature of the unconventional superconductivity and a competing
+charge order. Achieving orbital-specific control of the electronic structure to
+allow coupling pathways across adjacent planes would enable direct assessment
+of the role of dimensionality in the intertwined orders. Using Cu-$L_3$ and
+Pr-$M_5$ resonant x-ray scattering and first-principles calculations, we report
+a highly correlated three-dimensional charge order in Pr-substituted
+YBa$_2$Cu$_3$O$_{7}$, where the Pr $f$-electrons create a direct orbital bridge
+between CuO$_2$ planes. With this, we demonstrate that interplanar orbital
+engineering can be used to surgically control electronic phases in correlated
+oxides and other layered materials.",2202.00852v1
+2022-03-16,Resource estimations for the Hamiltonian simulation in correlated electron materials,"Correlated electron materials, such as superconductors and magnetic
+materials, are regarded as fascinating targets in quantum computing. However,
+the quantitative resources, specifically the number of quantum gates and
+qubits, required to perform a quantum algorithm to simulate correlated electron
+materials remain unclear. In this study, we estimate the resources required for
+the Hamiltonian simulation algorithm for correlated electron materials,
+specifically for organic superconductors, iron-based superconductors, binary
+transition metal oxides, and perovskite oxides, using the fermionic swap
+network. The effective Hamiltonian derived using the $ab~initio$ downfolding
+method is adopted for the Hamiltonian simulation, and a procedure for the
+resource estimation by using the fermionic swap network for the effective
+Hamiltonians including the exchange interactions is proposed. For example, in
+the system for the $10^2$ unit cells, the estimated number of gates per Trotter
+step and qubits are approximately $10^7$ and $10^3$, respectively, on average
+for the correlated electron materials. Furthermore, our results show that the
+number of interaction terms in the effective Hamiltonian, especially for the
+Coulomb interaction terms, is dominant in the gate resources when the number of
+unit cells constituting the whole system is up to $10^2$, whereas the number of
+fermionic swap operations is dominant when the number of unit cells is more
+than $10^3$.",2203.08446v3
+2022-04-01,High-resolution Compton spectroscopy using X-ray microcalorimeters,"X-ray Compton spectroscopy is one of the few direct probes of the electron
+momentum distribution of bulk materials in ambient and operando environments.
+We report high-resolution inelastic X-ray scattering experiments with high
+momentum and energy transfer performed at a storage-ring-based high-energy
+X-ray light source facility using an X-ray microcalorimeter detector. Compton
+profiles were measured for lithium and cobalt oxide powders relevant to
+lithium-ion battery research. Spectroscopic analysis of the measured Compton
+profiles shows high-sensitivity to the low-Z elements and oxidation states. The
+lineshape analysis of the measured Compton profiles in comparison with computed
+Hartree-Fock profiles is limited by the resolution of the energy-resolving
+semiconductor detector. We have characterized an X-ray transition-edge sensor
+microcalorimeter detector for high-resolution Compton scattering experiments
+using a bending magnet source at the Advanced Photon Source (APS) with a double
+crystal monochromator providing monochromatic photon energies near 27.5 keV.
+The momentum resolution below 0.16 atomic units was measured yielding an
+improvement of more than a factor of 7 over a state-of-the-art silicon drift
+detector for the same scattering geometry. Furthermore, the lineshapes of
+narrow valence and broad core electron profiles of sealed lithium metal were
+clearly resolved using an X-ray microcalorimeter detector compared to smeared
+and broadened lineshapes observed when using a silicon drift detector.
+High-resolution Compton scattering using the energy-resolving detector shown
+here presents new opportunities for spatial imaging of electron momentum
+distributions for a wide class of materials with applications ranging from
+electrochemistry to condensed matter physics.",2204.00568v1
+2022-05-12,Pivotal Role of Intersite Hubbard Interactions in Fe-doped $α$-MnO$_2$,"We present a first-principles investigation of the structural, electronic,
+and magnetic properties of the pristine and Fe-doped $\alpha$-MnO$_2$ using
+density-functional theory with extended Hubbard functionals. The onsite $U$ and
+intersite $V$ Hubbard parameters are determined from first principles and
+self-consistently using density-functional perturbation theory in the basis of
+L\""owdin-orthogonalized atomic orbitals. For the pristine $\alpha$-MnO$_2$ we
+find that the so-called C2-AFM spin configuration is the most energetically
+favorable, in agreement with the experimentally observed antiferromagnetic
+ground state. For the Fe-doped $\alpha$-MnO$_2$ two types of doping are
+considered: Fe insertion in the $2 \times 2$ tunnels and partial substitution
+of Fe for Mn. We find that the interstitial doping preserves the C2-AFM spin
+configuration of the host lattice only when both onsite $U$ and intersite $V$
+Hubbard corrections are included, while for the substitutional doping the
+onsite Hubbard $U$ correction alone is able to preserve the C2-AFM spin
+configuration of the host lattice. The oxidation state of Fe is found to be
+$+2$ and $+4$ in the case of the interstitial and substitutional doping,
+respectively, while the oxidation state of Mn is $+4$ in both cases. This work
+paves the way for accurate studies of other MnO$_2$ polymorphs and complex
+transition-metal compounds when the localization of $3d$ electrons occurs in
+the presence of strong covalent interactions with ligands.",2205.05977v2
+2022-09-05,Surface-phase superconductivity in Mg-deficient V-doped MgTi$_2$O$_4$ spinel,"Around fifty years ago, LiTi$_2$O$_4$ was reported to be first spinel oxide
+to exhibit a superconducting transition with highest T$_c$ $\approx$ 13.7 K.
+Recently, MgTi$_2$O$_4$ has been found to be the only other spinel oxide to
+reveal a superconducting transition with a T$_c$ $\approx$ 3 K, however, its
+superconducting state is realized only in thin film superlattices involving
+SrTiO$_3$. We find that a V-doped Mg$_{1-x}$Ti$_2$O$_4$ phase, which gets
+stabilized as a thin surface layer on top of stoichiometric and insulating
+V-doped MgTi$_2$O$_4$ bulk sample, exhibits high-temperature superconductivity
+with T$_c$ $\approx$ 16 K. The superconducting transition is also confirmed
+through a concomitant sharp diamagnetic transition immediately below T$_c$. The
+spinel phase of the superconducting surface layer is elucidated through
+grazing-incidence X-ray diffraction and Micro-Raman spectroscopy. A small shift
+of the sharp superconducting transition temperature ($\sim$ 4 K) with
+application of a high magnetic field (upto 9 Tesla) suggests a very high
+critical field for the system, $\sim$ 25 Tesla. Thus, V-doped
+Mg$_{1-x}$Ti$_2$O$_4$ exhibits the highest T$_c$ among spinel superconductors
+and also possesses a very high critical field.",2209.02053v2
+2022-09-29,The importance of electronic correlations in exploring the exotic phase diagram of layered Li$_x$MnO$_2$,"Using ab initio dynamical mean-field theory we explore the electronic and
+magnetic states of layered Li$_x$MnO$_2$ as a function of $x$, the state of
+charge. Constructing real-space Wannier projections of Kohn-Sham orbitals based
+on the low-energy subspace of Mn $3d$ states and solving a multi-impurity
+problem, our approach focuses on local correlations at Mn sites. The
+antiferromagnetic insulating state in LiMnO$_2$ has a moderate N\'{e}el
+temperature of $T_N=296\,K$ in agreement with experimental studies. Upon
+delithiation the system proceeds through a number of states: ferrimagnetic
+correlated metals at $x$=0.92, 0.83; multiple charge disproportionated
+ferromagnetic correlated metals with large quasiparticle weights at $x$=0.67,
+0.50, 0.33; ferromagnetic metals with small quasiparticle weights at $x$=0.17,
+0.08 and an antiferromagnetic insulator for the fully delithiated state,
+$x=0.0$. At moderate states of charge, $x=0.67-0.33$, a mix of +3/+4 formal
+oxidation states of Mn is observed, while the overall nominal oxidation of Mn
+state changes from +3 in LiMnO$_2$ to +4 in MnO$_2$. In all these cases the
+high-spin state emerges as the most likely state in our calculations
+considering the full $d$~manifold of Mn based on the proximity of $e_g$ levels
+in energy to $t_{2g}$. The quasiparticle peaks in the correlated metallic
+states were attributed to polaronic states based on previous literature for
+similar isoelectronic JT driven materials, arising due to non-Fermi liquid type
+behaviour of the strongly correlated system.",2209.14682v3
+2022-10-19,Evolution of local atomic structure accompanying devitrification of amorphous Ni-Zr alloy thin films,"Thin film metallic glasses undergoing devitrification can form partially
+crystallized or fully crystallized materials with novel structural and magnetic
+properties. The development of desired and tunable properties of such systems
+drives the need to understand the mechanism of their thermal evolution at the
+atomic level. Co-sputtered amorphous Ni-Zr alloy thin films which were
+thermally annealed in steps of 200 deg C from room temperature up to 800 deg C,
+were observed to undergo an amorphous-to-crystalline transformation. Evolutions
+in local atomic structure, including oxide formation and depletion during this
+devitrification process, were determined using a combination of X-ray
+reflectivity (XRR), grazing incidence X-ray diffraction (GIXRD) and Extended
+X-ray Absorption Fine Structure (EXAFS) techniques. The most probable phase of
+the alloy was determined as Ni7Zr2; undergoing a polymorphous transformation.
+The slight oxide content in the films was also noted to decrease rapidly as
+annealing proceeded; leaving the crystallization pathway unhindered. Modelling
+and analyses of XRR and GIXRD data showed that film thickness decreased with
+annealing while long range order increased. Pair distribution function peak
+widths were observed to decrease with annealing, indicating a control over
+structural disorder in the system as it transitioned from the amorphous to
+crystalline state. Partial atomic distribution in the environment of each
+constituent was examined at every stage of annealing through EXAFS
+measurements, which gave proper insight into atomic scale changes to the order
+present. Detailed analyses through these techniques gave coherent results, thus
+providing a true picture of the thermal evolution process of devitrification in
+this technologically useful material.",2210.10399v1
+2022-11-10,Honeycomb oxide heterostructure: a new platform for Kitaev quantum spin liquid,"Kitaev quantum spin liquid, massively quantum entangled states, is so scarce
+in nature that searching for new candidate systems remains a great challenge.
+Honeycomb heterostructure could be a promising route to realize and utilize
+such an exotic quantum phase by providing additional controllability of
+Hamiltonian and device compatibility, respectively. Here, we provide epitaxial
+honeycomb oxide thin film Na3Co2SbO6, a candidate of Kitaev quantum spin liquid
+proposed recently. We found a spin glass and antiferromagnetic ground states
+depending on Na stoichiometry, signifying not only the importance of Na vacancy
+control but also strong frustration in Na3Co2SbO6. Despite its classical ground
+state, the field-dependent magnetic susceptibility shows remarkable scaling
+collapse with a single critical exponent, which can be interpreted as evidence
+of quantum criticality. Its electronic ground state and derived spin
+Hamiltonian from spectroscopies are consistent with the predicted Kitaev model.
+Our work provides a unique route to the realization and utilization of Kitaev
+quantum spin liquid.",2211.05376v3
+2023-02-09,Structural changes induced by electric currents in a single crystal of Pr$_2$CuO$_4$,"We demonstrate a novel approach to the structural and electronic property
+modification of perovskites, focusing on Pr$_2$CuO$_4$, an undoped parent
+compound of a class of electron-doped copper-oxide superconductors. Currents
+were passed parallel or perpendicular to the copper-oxygen layers with the
+voltage ramped up until a rapid drop in the resistivity was achieved, a process
+referred to as ""flash"". The current was then further increased tenfold in
+current-control mode. This state was quenched by immersion into liquid
+nitrogen. Flash can drive many compounds into different atomic structures with
+new properties, whereas the quench freezes them into a long-lived state.
+Single-crystal neutron diffraction of as-grown and modified Pr$_2$CuO$_4$
+revealed a $\sqrt{10}$x$\sqrt{10}$ superlattice due to oxygen-vacancy order.
+The diffraction peak intensities of the superlattice of the modified sample
+were significantly enhanced relative to the pristine sample. Raman-active
+phonons in the modified sample were considerably sharper. Measurements of
+electrical resistivity, magnetization and two-magnon Raman scattering indicate
+that the modification affected only the Pr-O layers, but not the Cu-O planes.
+These results point to enhanced oxygen-vacancy order in the modified samples
+well beyond what can be achieved without passing electrical current. Our work
+opens a new avenue toward electric field/quench control of structure and
+properties of layered perovskite oxides.",2302.04385v2
+2023-03-09,Materials challenges for SrRuO3: from conventional to quantum electronics,"The need for faster and more miniaturised electronics is challenging
+scientists to develop novel forms of electronics based on quantum degrees of
+freedom different from electron charge. In this fast-developing field, often
+referred to as quantum electronics, the metal-oxide perovskite SrRuO3 can play
+an important role thanks to its diverse physical properties, which have been
+intensively investigated, mostly for conventional electronics. In addition to
+being chemically stable, easy to fabricate with high quality and to grow
+epitaxially onto many oxides - these are all desirable properties also for
+conventional electronics - SrRuO3 has interesting properties for quantum
+electronics like itinerant ferromagnetism and metallic behaviour, strong
+correlation between magnetic anisotropy and spin-orbit coupling,
+strain-tuneable magnetisation, anomalous Hall and Berry effects. In this
+Research Update, after describing the main phenomena emerging from the
+interplay between spin, orbital, lattice and topological quantum degrees of
+freedom in SrRuO3, we discuss the challenges still open to achieve control over
+these phenomena. We then provide our perspectives on the most promising
+applications of SrRuO3 for devices for conventional and quantum electronics. We
+suggest new device configurations and discuss the materials challenges for
+their realisation. For conventional electronics, we single out applications
+where SrRuO3 devices can bring competitive advantages over existing ones. For
+quantum electronics, we propose devices that can help gain a deeper
+understanding of quantum effects in SrRuO3 to exploit them for quantum
+technologies. We finally give an outlook about properties of SrRuO3 still
+waiting for discovery and applications that may stem from them.",2303.05114v1
+2023-10-07,Giant 2D Skyrmion Topological Hall Effect with Ultrawide Temperature Window and Low-Current Manipulation in 2D Room-Temperature Ferromagnetic Crystals,"The discovery and manipulation of topological Hall effect (THE), an abnormal
+magnetoelectric response mostly related to the Dzyaloshinskii-Moriya
+interaction (DMI), are promising for next-generation spintronic devices based
+on topological spin textures such as magnetic skyrmions. However, most
+skyrmions and THE are stabilized in a narrow temperature window either below or
+over room temperature with high critical current manipulation. It is still
+elusive and challenging to achieve large THE with both wide temperature window
+till room temperature and low critical current manipulation. Here, by using
+controllable, naturally-oxidized, sub-20 and sub-10 nm 2D van der Waals
+room-temperature ferromagnetic Fe3GaTe2-x crystals, robust 2D THE with
+ultrawide temperature window ranging in three orders of magnitude from 2 to 300
+K is reported, combining with giant THE of ~5.4 micro-ohm cm at 10 K and ~0.15
+micro-ohm cm at 300 K which is 1-3 orders of magnitude larger than that of all
+known room-temperature 2D skyrmion systems. Moreover, room-temperature
+current-controlled THE is also realized with a low critical current density of
+~6.2*10^5 A cm^-2. First-principles calculations unveil natural
+oxidation-induced highly-enhanced 2D interfacial DMI reasonable for robust
+giant THE. This work paves the way to room-temperature, electrically-controlled
+2D THE-based practical spintronic devices.",2310.04663v1
+2023-10-11,Multifunctional magnetic oxide-MoS$_2$ heterostructures on silicon,"Correlated oxides and related heterostructures are intriguing for developing
+future multifunctional devices by exploiting their exotic properties, but their
+integration with other materials, especially on Si-based platforms, is
+challenging. Here, van der Waals heterostructures of
+La$_{0.7}$Sr$_{0.3}$MnO$_3$ (LSMO), a correlated manganite perovskite, and
+MoS$_2$ are demonstrated on Si substrates with multiple functions. To overcome
+the problems due to the incompatible growth process, technologies involving
+freestanding LSMO membranes and van der Waals force-mediated transfer are used
+to fabricate the LSMO-MoS$_2$ heterostructures. The LSMO-MoS$_2$
+heterostructures exhibit a gate-tunable rectifying behavior, based on which
+metal-semiconductor field-effect transistors (MESFETs) with on-off ratios of
+over 104 can be achieved. The LSMO-MoS$_2$ heterostructures can function as
+photodiodes displaying considerable open-circuit voltages and photocurrents. In
+addition, the colossal magnetoresistance of LSMO endows the LSMO-MoS$_2$
+heterostructures with an electrically tunable magnetoresponse at room
+temperature. This work not only proves the applicability of the LSMO-MoS$_2$
+heterostructure devices on Si-based platform but also demonstrates a paradigm
+to create multifunctional heterostructures from materials with disparate
+properties.",2310.07783v1
+2024-01-23,Integration of High-Tc Superconductors with High Q Factor Oxide Mechanical Resonators,"Micro-mechanical resonators are building blocks of a variety of applications
+in basic science and applied electronics. This device technology is mainly
+based on well-established and reproducible silicon-based fabrication processes
+with outstanding performances in term of mechanical Q factor and sensitivity to
+external perturbations. Broadening the functionalities of MEMS by the
+integration of functional materials is a key step for both applied and
+fundamental science. However, combining functional materials and silicon-based
+compounds is challenging. An alternative approach is fabricating MEMS based on
+complex heterostructures made of materials inherently showing a variety of
+physical properties such as transition metal oxides. Here, we report on the
+integration of a high-Tc superconductor YBa2Cu3O7 (YBCO) with high Q factor
+micro-bridge resonator made of a single-crystal LaAlO3 (LAO) thin film. LAO
+resonators are tensile strained, with a stress of 345 MPa, show Q factor in the
+range of tens of thousands, and have low roughness. The topmost YBCO layer
+deposited by Pulse Laser Deposition shows a superconducting transition starting
+at 90 K with zero resistance below 78 K. This result opens new possibilities
+towards the development of advanced transducers, such as bolometers or magnetic
+field detectors, as well as basic science experiments in solid state physics,
+material science, and quantum opto-mechanics.",2401.12758v1
+2024-02-05,Tracing d-d transitions in FePS$_{3}$ on ultrafast time scales,"Excitations between localized 3d states of transition metal ions within
+crystalline solids, commonly known as d-d transitions, play a pivotal role in
+diverse phenomena across solid state physics, materials science, and chemistry.
+These transitions contribute to the coloration in transition metal oxides,
+catalytic processes on oxide surfaces, and high-temperature superconductivity.
+They also couple optical excitation to quantized collective phenomena such as
+phonons and magnons in magnetic systems. Until now, an experimental method to
+unravel the complex quasiparticle dynamics associated with d-d transitions has
+remained elusive. We bridge this gap by demonstrating that d-d transitions can
+be distinctly traced in momentum space and time using time- and angle-resolved
+photoelectron spectroscopy (trARPES). Through this approach, we can assign
+specific momentum-dependent characteristics and elucidate the decay mechanisms
+of specific d-d transitions in FePS$_{3}$, a two-dimensional van der Waals
+antiferromagnet with a rich array of quantum phenomena stemming from d-d
+transitions. This study pioneers the use of ARPES in probing the dynamics of
+d-d transitions across a wide spectrum of solid-state systems.",2402.03018v1
+2024-03-11,Bulk and interface spin-orbit torques in Pt/Co/MgO thin film structures,"We investigate the origin of spin-orbit torques (SOTs) in archetypical
+Pt/Co/MgO thin films structures by performing harmonic Hall measurements. The
+behaviour of the damping like (DL) effective field ($h_{DL}$) with varying the
+Pt layer thickness and the Co layer thickness indicates that bulk spin-Hall
+effect (SHE) in Pt is mainly responsible for DL-SOT. The insertion of a Pd
+ultrathin layer at the Pt/Co interface leads to a step decrease in $h_{DL}$,
+attributed to the modification of interfacial spin transparency. Further
+increase in Pd thickness led to a reduction of the interfacial spin-orbit
+coupling (iSOC) quantified by the decrease in the surface magnetic anisotropy.
+The consistent insensitivity of $h_{DL}$ to variations in iSOC at the bottom
+Pt/Co interface and oxidation at the top Co/MgO interface provides additional
+evidence for the bulk SHE origin of DL-SOT. The strong reduction in the
+field-like (FL) torque effective field ($h_{FL}$) with decreasing iSOC at the
+Pt/Co interface points to the interfacial nature of FL-SOT, either due to iSOC
+induced interfacial spin-currents or to the Rashba-Edelstein effect at the
+Pt/Co interface. Furthermore, we demonstrate that a FL-SOT develops at the top
+Co/MgO interface opposing the one generated at the bottom Pt/Co interface,
+whose strength increases with Co/MgO interfacial oxidation, and attributed to
+the Rashba-Edelstein effect.",2403.06627v1
+2012-03-17,Electrical transport properties of nanostructured ferromagnetic perovskite oxides La_0.67Ca_0.33MnO_3 and La_0.5Sr_0.5CoO_3 at low temperatures (5 K > T >0.3 K) and high magnetic field,"We report a comprehensive study of the electrical and magneto-transport
+properties of nanocrystals of La_0.67Ca_0.33MnO_3 (LCMO) (with size down to 15
+nm) and La_0.5Sr_0.5CoO_3 (LSCO) (with size down to 35 nm) in the temperature
+range 0.3 K to 5 K and magnetic fields upto 14 T. The transport,
+magnetotransport and non-linear conduction (I-V curves) were analysed using the
+concept of Spin Polarized Tunnelling in the presence of Coulomb blockade. The
+activation energy of transport, \Delta, was used to estimate the tunnelling
+distances and the inverse decay length of the tunnelling wave function (\chi)
+and the height of the tunnelling barrier (\Phi_B). The magnetotransport data
+were used to find out the magnetic field dependences of these tunnelling
+parameters. The data taken over a large magnetic field range allowed us to
+separate out the MR contributions at low temperatures arising from tunnelling
+into two distinct contributions. In LCMO, at low magnetic field, the transport
+and the MR are dominated by the spin polarization, while at higher magnetic
+field the MR arises from the lowering of the tunnel barrier by the magnetic
+field leading to an MR that does not saturate even at 14 T. In contrast, in
+LSCO, which does not have substantial spin polarization, the first contribution
+at low field is absent, while the second contribution related to the barrier
+height persists. The idea of inter-grain tunnelling has been validated by
+direct measurements of the non-linear I-V data in this temperature range and
+the I-V data was found to be strongly dependent on magnetic field. We made the
+important observation that a gap like feature (with magnitude ~ E_C, the
+Coulomb charging energy) shows up in the conductance g(V) at low bias for the
+systems with smallest nanocrystal size at lowest temperatures (T < 0.7 K). The
+gap closes as the magnetic field and the temperature are increased.",1203.3873v1
+2016-07-02,Interface-Induced Phenomena in Magnetism,"This article reviews static and dynamic interfacial effects in magnetism,
+focusing on interfacially-driven magnetic effects and phenomena associated with
+spin-orbit coupling and intrinsic symmetry breaking at interfaces. It provides
+a historical background and literature survey, but focuses on recent progress,
+identifying the most exciting new scientific results and pointing to promising
+future research directions. It starts with an introduction and overview of how
+basic magnetic properties are affected by interfaces, then turns to a
+discussion of charge and spin transport through and near interfaces and how
+these can be used to control the properties of the magnetic layer. Important
+concepts include spin accumulation, spin currents, spin transfer torque, and
+spin pumping. An overview is provided to the current state of knowledge and
+existing review literature on interfacial effects such as exchange bias,
+exchange spring magnets, spin Hall effect, oxide heterostructures, and
+topological insulators. The article highlights recent discoveries of
+interface-induced magnetism and non-collinear spin textures, non-linear
+dynamics including spin torque transfer and magnetization reversal induced by
+interfaces, and interfacial effects in ultrafast magnetization processes.",1607.00439v4
+2020-07-18,Giant magneto-birefringence effect and tuneable colouration of 2D crystals' suspensions,"One of the long sought-after goals in manipulation of light through
+light-matter interactions is the realization of magnetic-field-tuneable
+colouration, so-called magneto-chromatic effect, which holds great promise for
+optical, biochemical and medical applications due to its contactless and
+non-invasive nature. This goal can be achieved by magnetic-field controlled
+birefringence, where colours are produced by the interference between
+phase-retarded components of transmitted polarised light. Thus far
+birefringence-tuneable coloration has been demonstrated using electric field,
+material chirality and mechanical strain but magnetic field control remained
+elusive due to either weak magneto-optical response of transparent media or low
+transmittance to visible light of magnetically responsive media, such as
+ferrofluids. Here we demonstrate magnetically tuneable colouration of aqueous
+suspensions of two-dimensional cobalt-doped titanium oxide which exhibit an
+anomalously large magneto-birefringence effect. The colour of the suspensions
+can be tuned over more than two wavelength cycles in the visible range by
+moderate magnetic fields below 0.8 T. We show that such giant magneto-chromatic
+response is due to particularly large phase retardation (>3 pi) of the
+polarised light, which in its turn is a combined result of a large
+Cotton-Mouton coefficient (three orders of magnitude larger than for known
+liquid crystals), relatively high saturation birefringence (delta n = 2 x
+10^-4) and high transparency of our suspensions to visible light. The work
+opens a new avenue to achieve tuneable colouration through engineered magnetic
+birefringence and can readily be extended to other magnetic 2D nanocrystals.
+The demonstrated effect can be used in a variety of magneto-optical
+applications, including magnetic field sensors, wavelength-tuneable optical
+filters and see-through printing.",2007.09388v1
+2020-01-15,"Emergence of weak pyrochlore phase and signature of field induced spin ice ground state in Dy$_{2-x}$La$_{x}$Zr$_{2}$O$_{7}$; x = 0, 0.15, 0.3","The pyrochlore oxides Dy$_{2}$Ti$_{2}$O$_{7}$ and Ho$_{2}$Ti$_{2}$O$_{7}$ are
+well studied spin ice systems and have shown the evidences of magnetic monopole
+excitations. Unlike these, Dy$_{2}$Zr$_{2}$O$_{7}$ is reported to crystallize
+in a distorted fluorite structure. We present here the magnetic and heat
+capacity studies of La substituted Dy$_{2}$Zr$_{2}$O$_{7}$. Our findings
+suggest the absence of spin ice state in Dy$_{2}$Zr$_{2}$O$_{7}$ but the
+emergence of the magnetic field induced spin freezing near T $\approx$ 10 K in
+ac susceptibility measurements which is similar to Dy$_{2}$Ti$_{2}$O$_{7}$. The
+magnetic heat capacity of Dy$_{2}$Zr$_{2}$O$_{7}$ shows a shift in the peak
+position from 1.2 K in zero field to higher temperatures in the magnetic field,
+with the corresponding decrease in the magnetic entropy. The low temperature
+magnetic entropy at 5 kOe field is Rln2 - (1/2)Rln(3/2) which is same as for
+the spin ice state. Substitution of non-magnetic, isovalent La$^{3+}$ for
+Dy$^{3+}$ gradually induces the structural change from highly disordered
+fluorite to weakly ordered pyrochlore phase. The La$^{3+}$ substituted
+compounds with less distorted pyrochlore phase show the spin freezing at lower
+field which strengthens further on the application of magnetic field. Our
+results suggest that the spin ice state can be stabilized in
+Dy$_{2}$Zr$_{2}$O$_{7}$ either by slowing down of the spin dynamics or by
+strengthening the pyrochlore phase by suitable substitution in the system.",2001.05244v2
+2023-02-03,Universality of the {\bf q}=1/2 Orbital Magnetism in the Pseudogap Phase of the High-$T_c$ superconductor $\rm YBa_{2}Cu_{3}O_{6+x}$,"Several decades of debate have centered around the nature of the enigmatic
+pseudo-gap state in high temperature superconducting copper oxides. Recently,
+we reported polarized neutron diffraction measurements that suggested the
+existence of a magnetic texture bound to the pseudo-gap phase [Bounoua, {\it et
+al}. Communications Physics 5, 268 (2022)]. Such a magnetic texture is likely
+to involve the spontaneous appearance of loop currents within the CuO$_2$ unit
+cells, which give birth to complex correlated patterns. In the underdoped ${\rm
+YBa_{2}Cu_{3}O_{6.6}}$, the magnetic structure factor of such an orbital
+magnetic texture gives rise to two distinct magnetic responses at {\bf q}=0 and
+{\bf q}=1/2. As this pattern alters the lattice translation invariance, such a
+state of matter could contribute to an instability of the Fermi surface. Here,
+we report polarized neutron scattering measurements on a nearly optimally doped
+high quality single crystal of ${\rm YBa_{2}Cu_{3}O_{6.9}}$ that exhibits the
+same {\bf q}=1/2 magnetism and a weakly overdoped ${\rm YBa_{2}Cu_{3}O_{7}}$
+sample where this signal is no longer sizeable. The in-plane and out-of-plane
+magnetic neutron scattering intensities in ${\rm YBa_{2}Cu_{3}O_{6.9}}$ (at
+{\bf q}=1/2) and ${\rm YBa_{2}Cu_{3}O_{6.85}}$ (at {\bf q}=0), reported
+previously, display the same temperature dependent hallmarks. The magnitudes of
+both {\bf q}=0 and {\bf q}=1/2 magnetic signals further exhibit the same trends
+upon doping in ${\rm YBa_{2}Cu_{3}O_{6+x}}$, confirming that they are likely
+intertwined.",2302.01870v2
+2023-03-12,Emergence of a Non-van der Waals Magnetic Phase in a van der Waals Ferromagnet,"Manipulation of long-range order in two-dimensional (2D) van der Waals (vdW)
+magnetic materials (e.g., CrI$_3$, CrSiTe$_3$ etc.), exfoliated in few-atomic
+layer, can be achieved via application of electric field,
+mechanical-constraint, interface engineering, or even by chemical
+substitution/doping. Usually, active surface oxidation due to the exposure in
+the ambient condition and hydrolysis in the presence of water/moisture causes
+degradation in magnetic nanosheets which, in turn, affects the
+nanoelectronic/spintronic device performance. Counterintuitively, our current
+study reveals that exposure to the air at ambient atmosphere results in advent
+of a stable nonlayered secondary ferromagnetic phase in the form of
+Cr$_2$Te$_3$ (T$_{C2}$ ~ 160 K) in the parent vdW magnetic semiconductor
+Cr$_2$Ge$_2$Te$_6$ (T$_{C1}$ ~ 69 K). In addition, the magnetic anisotropy
+energy (MAE) enhances in the hybrid by an order from the weakly anisotropic
+pristine Cr$_2$Ge$_2$Te$_6$ crystal, increasing the stability of the FM ground
+state with time. Comparing with the freshly prepared Cr$_2$Ge$_2$Te$_6$, the
+coexistence of the two ferromagnetic phases in the time elapsed bulk crystal is
+confirmed through systematic investigation of crystal structure along with
+detailed dc/ac magnetic susceptibility, specific heat, and magnetotransport
+measurement. To capture the concurrence of the two ferromagnetic phases in a
+single material, Ginzburg-Landau theory with two independent order parameters
+(as magnetization) with a coupling term can be introduced. In contrast to
+rather common poor environmental stability of the vdW magnets, our results open
+possibilities of finding air-stable novel materials having multiple magnetic
+phases.",2303.06732v1
+2024-01-09,2024 Roadmap on Magnetic Microscopy Techniques and Their Applications in Materials Science,"Considering the growing interest in magnetic materials for unconventional
+computing, data storage, and sensor applications, there is active research not
+only on material synthesis but also characterisation of their properties. In
+addition to structural and integral magnetic characterisations, imaging of
+magnetization patterns, current distributions and magnetic fields at nano- and
+microscale is of major importance to understand the material responses and
+qualify them for specific applications. In this roadmap, we aim to cover a
+broad portfolio of techniques to perform nano- and microscale magnetic imaging
+using SQUIDs, spin center and Hall effect magnetometries, scanning probe
+microscopies, x-ray- and electron-based methods as well as magnetooptics and
+nanoMRI. The roadmap is aimed as a single access point of information for
+experts in the field as well as the young generation of students outlining
+prospects of the development of magnetic imaging technologies for the upcoming
+decade with a focus on physics, materials science, and chemistry of planar, 3D
+and geometrically curved objects of different material classes including 2D
+materials, complex oxides, semi-metals, multiferroics, skyrmions,
+antiferromagnets, frustrated magnets, magnetic molecules/nanoparticles, ionic
+conductors, superconductors, spintronic and spinorbitronic materials.",2401.04793v1
+2013-11-30,Electronic Transport in Composites of Graphite Oxide with Carbon Nanotubes,"We show that the presence of electrically insulating graphite oxide (GO)
+within a single wall carbon nanotube network strongly enhances electrical
+conductivity, whereas reduced graphite oxide, even though electrically
+conductive, suppresses electrical conductivity within a composite network with
+single wall carbon nanotubes. Measurements of Young modulus and of Raman
+spectra strongly support our interpretation of the indirect role of the oxide
+groups, present in graphite oxide within the single wall carbon
+nanotubes/graphite oxide composite, through electronic doping of metallic
+single wall carbon nanotubes.",1312.0152v1
+2008-07-07,Oxidative stress response: a proteomic view,"The oxidative stress response is characterized by various effects on a range
+of biologic molecules. When examined at the protein level, both expression
+levels and protein modifications are altered by oxidative stress. While these
+effects have been studied in the past by classic biochemical methods, the
+recent onset of proteomics methods has allowed the oxidative stress response to
+be studied on a much wider scale. The input of proteomics in the study of
+oxidative stress response and in the evidence of an oxidative stress component
+in biologic phenomena is reviewed in this paper.",0807.1041v1
+2000-01-11,Magnetic Susceptibilities of Spin-1/2 Antiferromagnetic Heisenberg Ladders and Applications to Ladder Oxide Compounds,"A comprehensive theoretical and experimental study is presented of the
+magnetic susceptibility versus temperature \chi(T) of spin S = 1/2 two- and
+three-leg Heisenberg ladders and ladder oxide compounds. Extensive quantum
+Monte Carlo simulations of \chi(T) were carried out for both isolated and
+coupled two-leg ladders with spatially anisotropic intraladder exchange.
+Accurate fits to these and related literature QMC data were obtained. We have
+also calculated the one- and two-magnon dispersion relations and the dynamical
+spin structure factor for anisotropic isolated 2 x 12 ladders. The exchange
+constants in the two-leg ladder compound SrCu2O3 are estimated from LDA+U
+calculations. We report the detailed crystal structure of SrCu2O3 and of the
+three-leg ladder compound Sr2Cu3O5. New experimental \chi(T) data are reported
+for the two-leg ladder cuprates SrCu2O3 and LaCuO_{2.5}, and for the
+(nominally) two-leg ladder vanadates CaV2O5 and MgV2O5. The new and literature
+\chi(T) data for these compounds and for Sr2Cu3O5 are modeled using our QMC
+\chi(T) simulation fits, and the exchange coupling constants between the
+spins-1/2 are thereby estimated for each material. The surpisingly strong
+spatial anisotropy of the bilinear intraladder exchange constants in the
+cuprate compounds is discussed together with the results of other experiments
+sensitive to this anisotropy. Recent theoretical predictions are discussed
+including those which indicate that a four-spin cyclic exchange interaction
+within a Cu4 plaquette is important to determining the magnetic properties and
+which can significantly influence the exchange interactions estimated from
+\chi(T) data assuming the presence of only bilinear exchange.",0001147v1
+2012-11-19,Anomalous scaling of spin accumulation in ferromagnetic tunnel devices with silicon and germanium,"The magnitude of spin accumulation created in semiconductors by electrical
+injection of spin-polarized electrons from a ferromagnetic tunnel contact is
+investigated, focusing on how the spin signal detected in a Hanle measurement
+varies with the thickness of the tunnel oxide. An extensive set of
+spin-transport data for Si and Ge magnetic tunnel devices reveals a scaling
+with the tunnel resistance that violates the core feature of available
+theories, namely, the linear proportionality of the spin voltage to the
+injected spin current density. Instead, an anomalous scaling of the spin signal
+with the tunnel resistance is observed, following a power-law with an exponent
+between 0.75 and 1 over 6 decades. The scaling extends to tunnel resistance
+values larger than 10$^{9}$ $\Omega\mu m^2$, far beyond the regime where the
+classical impedance mismatch plays a role. This scaling is incompatible with
+existing theory for direct tunnel injection of spins into the semiconductor. It
+also demonstrates conclusively that the large spin signal does not originate
+from two-step tunneling via localized states near the oxide/semiconductor
+interface. Control experiments on devices with a non-magnetic metal (Ru)
+electrode, instead of the semiconductor, exhibit no Hanle spin signal, showing
+that spin accumulation in localized states within the tunnel barrier is also
+not responsible. Control devices in which the spin current is removed by
+inserting a non-magnetic interlayer exhibit no Hanle signals either, proving
+that the spin signals observed in the standard devices are genuine and
+originate from spin-polarized tunneling and the resulting spin accumulation.
+Altogether, the scaling results suggest that the spin signal is proportional to
+the applied bias voltage, rather than the (spin) current.",1211.4460v1
+2015-05-13,Multiferroic crossover in perovskite oxides,"Recently, the perovskite BiCoO$_3$ has been shown experimentally to be
+isostructural with PbTiO$_3$, while simultaneously the $d^6$ Co$^{3+}$ ion has
+a high spin ground state with $C$-type antiferromagnetic ordering. Using hybrid
+density functional calculations, we investigate the atomic, electronic and
+magnetic structure of BiCoO$_3$ to elucidate the origin of the multiferroic
+state. To begin with, we perform a qualitative trend sudy of the role of $d$
+electrons in affecting the tendency for perovskite materials to exhibit a
+ferroelectric distortion; this work initially explores a qualitative trend
+study in artificial cubic and tetragonal LaBO$_3$ perovskites. We choose La as
+the A-cation so as to remove the effects of Bi $6s$ hybridization. Through
+first-principles calculations of the LaBO$_3$ series, where B is a $d^0 - d^8$
+cation from the $3d$-block, the trend study reveals that increasing the $d$
+orbital occupation initially removes the tendency for a polar distortion, as
+expected. However, for high spin $d^5-d^7$ and $d^8$ cations a strong
+ferroelectric instability is recovered. We explained this effect in terms of
+the pseudo Jahn-Teller theory for ferroelectricity. It is shown that, in some
+cases, unpaired electron spins actually drive ferroelectricity, rather than
+inhibit it, which represents a shift in the understanding of how
+ferroelectricity and magnetism interact in perovskite oxides. It follows, that
+for the case of BiCoO$_3$, the Co$^{3+}$ ion plays a major role in the
+ferroelectric lattice instability. Importantly, the ferroelectric polarization
+is greatly enhanced when the Co$^{3+}$ ion is in the high spin state, when
+compared to the nonmagnetic, low spin state, and a large coupling of the
+electrical and magnetic polarization is present. Importantly, it is
+demonstrated that the ground spin state is switched by reducing the internal
+ferroelectric polarization.",1505.03249v4
+2018-02-27,Depth-resolved resonant inelastic x-ray scattering at a superconductor/half-metallic ferromagnet interface through standing-wave excitation,"We demonstrate that combining standing-wave (SW) excitation with resonant
+inelastic x-ray scattering (RIXS) can lead to depth resolution and interface
+sensitivity for studying orbital and magnetic excitations in correlated oxide
+heterostructures. SW-RIXS has been applied to multilayer heterostructures
+consisting of a superconductor La$_{1.85}$Sr$_{0.15}$CuO$_{4}$(LSCO) and a
+half-metallic ferromagnet La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ (LSMO). Easily
+observable SW effects on the RIXS excitations were found in these LSCO/LSMO
+multilayers. In addition, we observe different depth distribution of the RIXS
+excitations. The magnetic excitations are found to arise from the LSCO/LSMO
+interfaces, and there is also a suggestion that one of the dd excitations comes
+from the interfaces. SW-RIXS measurements of correlated-oxide and other
+multilayer heterostructures should provide unique layer-resolved insights
+concerning their orbital and magnetic excitations, as well as a challenge for
+RIXS theory to specifically deal with interface effects.",1802.09743v5
+2012-04-27,Effect of Boron substitution on the superconductivity of non-oxide perovskite MgCNi3,"We report synthesis, structural and magnetic (DC and AC) properties of Boron
+substituted MgCNi3 superconductor. A series of polycrystalline bulk samples
+Mg1.2C1.6-xBxNi3 (x = 0.0, 0.08 and 0.16) is synthesized through standard
+solid-state reaction route, which are found to crystallize in cubic perovskite
+structure with space group Pm3m. Rietveld analysis of observed XRD data show
+that lattice parameters expand from a = 3.8106 (4) {\AA} for pure, to 3.8164
+(2) {\AA} and 3.8173 (5) {\AA} for 5% and 10% Boron substituted samples
+respectively. DC magnetization exhibited superconducting transition (Tc) at
+around 7.3 K for pure sample, and the same decreases slightly with Boron
+substitution. The lower critical field (Hc1) at 2 K is around 150 Oe for pure
+sample, which increases slightly with Boron substitution. For pure sample the
+upper critical field (Hc2) being determined from AC susceptibility measurements
+is 11.6 kOe and 91.70 kOe with 50% and 90% diamagnetism criteria respectively,
+which decreases to 5.57 kOe and 42.5 kOe respectively for 10% Boron substituted
+sample. 10% Boron substitution at Carbon site has decreased both the Hc2 and
+Tc. On the other hand lower critical field (Hc1) at 2 K is slightly increased
+from around 150 Oe for pure sample, to 200 Oe for 10% Boron substituted sample.
+Seemingly, the Carbon site Boron substitution induced disorder though has
+increased slightly the Hc1 but with simultaneous decrease in superconducting
+transition temperature (Tc) and upper critical field (Hc2). The high relative
+proportion of Ni in studied MgCNi3 suggests that magnetic interactions are
+important and non-oxide perovskite structure make it interesting.",1204.6175v3
+2017-11-14,Strong spin-orbit coupling and magnetism in (111) (La$_{0.3}$Sr$_{0.7}$)(Al$_{0.65}$Ta$_{0.35})$/SrTiO$_3$,"Strong correlations, multiple lattice degrees of freedom, and the ease of
+doping make complex oxides a source of great research interest. Complex oxide
+heterointerfaces break inversion symmetry and can host a two dimensional
+carrier gas, which can display a variety of coexisting and competing phenomena.
+In the case of heterointerfaces based on SrTiO$_3$, many of these phenomena can
+be effectively tuned by using an electric gate, due to the large dielectric
+constant of SrTiO$_3$. Most studies so far have focused on (001) oriented
+heterostructures; however, (111) oriented heterostructures have recently gained
+attention due to the possibility of finding exotic physics in these systems due
+their hexagonal surface crystal symmetry. In this work, we use
+magnetoresistance to study the evolution of spin-orbit interaction and
+magnetism in a new system, (111) oriented
+(La$_{0.3}$Sr$_{0.7}$)(Al$_{0.65}$Ta$_{0.35}$)/SrTiO$_3$. At more positive
+values of the gate voltage, which correspond to high carrier densities, we find
+that transport is multiband, and dominated by high mobility carriers with a
+tendency towards weak localization. At more negative gate voltages, the carrier
+density is reduced, the high mobility bands are depopulated, and weak
+antilocalization effects begin to dominate, indicating that spin-orbit
+interaction becomes stronger. At millikelvin temperatures, and gate voltages
+corresponding to the strong spin-orbit regime, we observe hysteresis in
+magnetoresistance, indicative of ferromagnetism in the system. Our results
+suggest that in the (111)
+(La$_{0.3}$Sr$_{0.7}$)(Al$_{0.65}$Ta$_{0.35}$)/SrTiO$_3$ system, low mobility
+carriers which experience strong spin-orbit interactions participate in
+creating magnetic order in the system.",1711.05322v2
+2018-03-20,Unravelling Dzyaloshinskii-Moriya interaction and chiral nature of Graphene/Cobalt interface,"A major challenge for future spintronics is to develop suitable spin
+transport channels with long spin lifetime and propagation length. Graphene can
+meet these requirements, even at room temperature. On the other side, taking
+advantage of the fast motion of chiral textures, i.e., N\'eel-type domain walls
+and magnetic skyrmions, can satisfy the demands for high-density data storage,
+low power consumption and high processing speed. We have engineered epitaxial
+structures where an epitaxial ferromagnetic Co layer is sandwiched between an
+epitaxial Pt(111) buffer grown in turn onto MgO(111) substrates and a graphene
+layer. We provide evidence of a graphene-induced enhancement of the
+perpendicular magnetic anisotropy up to 4 nm thick Co films, and of the
+existence of chiral left-handed N\'eel-type domain walls stabilized by the
+effective Dzyaloshinskii-Moriya interaction (DMI) in the stack. The experiments
+show evidence of a sizeable DMI at the gr/Co interface, which is described in
+terms of a conduction electron mediated Rashba-DMI mechanism and points
+opposite to the Spin Orbit Coupling-induced DMI at the Co/Pt interface. In
+addition, the presence of graphene results in: i) a surfactant action for the
+Co growth, producing an intercalated, flat, highly perfect fcc film,
+pseudomorphic with Pt and ii) an efficient protection from oxidation. The
+magnetic chiral texture is stable at room temperature and grown on insulating
+substrate. Our findings open new routes to control chiral spin structures using
+interfacial engineering in graphene-based systems for future spin-orbitronics
+devices fully integrated on oxide substrates.",1803.07443v3
+2020-10-20,Origin of the Magnetic and Orbital ordering in $α$-Sr$_2$CrO$_4$,"Motivated by recent experimental progress in transition metal oxides with the
+K$_2$NiF$_4$ structure, we investigate the magnetic and orbital ordering in
+$\alpha$-Sr$_2$CrO$_4$. Using first principles calculations, first we derive a
+three-orbital Hubbard model, which reproduces the {\it ab initio} band
+structure near the Fermi level. The unique reverse splitting of $t_{2g}$
+orbitals in $\alpha$-Sr$_2$CrO$_4$, with the $3d^2$ electronic configuration
+for the Cr$^{4+}$ oxidation state, opens up the possibility of orbital ordering
+in this material. Using real-space Hartree-Fock for multi-orbital systems, we
+constructed the ground-state phase diagram for the two-dimensional compound
+$\alpha$-Sr$_2$CrO$_4$. We found stable ferromagnetic, antiferromagnetic,
+antiferro-orbital, and staggered orbital stripe ordering in robust regions of
+the phase diagram. Furthermore, using the density matrix renormalization group
+method for two-leg ladders with the realistic hopping parameters of
+$\alpha$-Sr$_2$CrO$_4$, we explore magnetic and orbital ordering for
+experimentally relevant interaction parameters. Again, we find a clear
+signature of antiferromagnetic spin ordering along with antiferro-orbital
+ordering at moderate to large Hubbard interaction strength. We also explore the
+orbital-resolved density of states with Lanczos, predicting insulating behavior
+for the compound $\alpha$-Sr$_2$CrO$_4$, in agreement with experiments.
+Finally, an intuitive understanding of the results is provided based on a
+hierarchy between orbitals, with $d_{xy}$ driving the spin order, while
+electronic repulsion and the effective one dimensionality of the movement
+within the $d_{xz}$ and $d_{yz}$ orbitals driving the orbital order.",2010.10342v1
+2021-07-09,"Complete crystallographic, spin-electronic and magnetic structure of (Co0.2Cr0.2Fe0.2Mn0.2Ni0.2)3O4: Unraveling the suppression of entropy in high entropy oxides","High entropy oxides (HEOs) are a rapidly emerging class of functional
+materials consisting of multiple principal cations. The original paradigm of
+HEOs assumes cationic occupations with the highest possible configurational
+entropy allowed by the composition and crystallographic structure. However, the
+fundamental question remains on the actual degree of configurational disorder
+in HEOs, especially, in systems with a low enthalpy barriers for cation
+anti-site mixing. Considering the experimental limitations due to the presence
+of multiple principal cations in HEOs, here we utilize a robust and
+cross-referenced characterization approach using soft X-ray magnetic circular
+dichroism, hard X-ray absorption spectroscopy, M\""ossbauer spectroscopy,
+neutron powder diffraction and SQUID magnetometry to study the competition
+between crystal field stabilization energy and configurational entropy
+governing the cation occupation in a spinel HEO (S-HEO),
+(Co$_{0.2}$Cr$_{0.2}$Fe$_{0.2}$Mn$_{0.2}$Ni$_{0.2}$)$_3$O$_4$. In contrast to
+the previous studies, the derived complete structural and spin-electronic
+model,
+(Co$_{0.6}$Fe$_{0.4}$)(Cr$_{0.3}$Fe$_{0.1}$Mn$_{0.3}$Ni$_{0.3}$)$_2$O$_4$,
+highlights a significant deviation from the hitherto assumed paradigm of
+entropy-driven non-preferential distribution of cations in HEOs. An immediate
+correlation of this result can be drawn with bulk as well as the local element
+specific magnetic properties, which are intrinsically dictated by cationic
+occupations in spinels. The real local lattice picture presented here provides
+an alternate viewpoint on ionic arrangement in HEOs, which is of fundamental
+interest for predicting and designing their structure-dependent
+functionalities.",2107.04274v2
+2022-05-02,Evidence for charge and spin order in single crystals of La$_3$Ni$_2$O$_7$ and La$_3$Ni$_2$O$_6$,"Charge and spin order is intimately related to superconductivity in copper
+oxide superconductors. To elucidate the competing orders in various nickel
+oxide compounds are crucial given the fact that superconductivity has been
+discovered in Nd$_{0.8}$Sr$_{0.2}$NiO$_2$ films. Herein, we report structural,
+electronic transport, magnetic, and thermodynamic characterizations on single
+crystals of La$_3$Ni$_2$O$_7$ and La$_3$Ni$_2$O$_6$. La$_3$Ni$_2$O$_7$ is
+metallic with mixed Ni$^{2+}$ and Ni$^{3+}$ valent states. Resistivity
+measurements yield two transition-like kinks at $\sim$110 and 153 K,
+respectively. The kink at 153 K is further revealed from magnetization and
+specific heat measurements, indicative of the formation of charge and spin
+order. La$_3$Ni$_2$O$_6$ single crystals obtained from topochemical reduction
+of La$_3$Ni$_2$O$_7$ are insulating and show an anomaly at $\sim$176 K on
+magnetic susceptibility. The transition-like behaviors of La$_3$Ni$_2$O$_7$ and
+La$_3$Ni$_2$O$_6$ are analogous to the charge and spin order observed in
+La$_4$Ni$_3$O$_{10}$ and La$_4$Ni$_3$O$_8$, suggesting charge and spin order is
+a common feature in the ternary La-Ni-O system with mixed-valent states of
+nickel.",2205.00950v1
+2004-09-29,Nanometer and sub-nanometer thin oxide films at surfaces of late transition metals,"If metal surfaces are exposed to sufficiently oxygen-rich environments,
+oxides start to form. Important steps in this process are the dissociative
+adsorption of oxygen at the surface, the incorporation of O atoms into the
+surface, the formation of a thin oxidic overlayer and the growth of the once
+formed oxide film. For the oxidation process of late transition metals (TM),
+recent experimental and theoretical studies provided a quite intriguing
+atomic-scale insight: The formed initial oxidic overlayers are not merely few
+atomic-layer thin versions of the known bulk oxides, but can exhibit structural
+and electronic properties that are quite distinct to the surfaces of both the
+corresponding bulk metals and bulk oxides. If such nanometer or even
+sub-nanometer surface oxide films are stabilized in applications, new
+functionalities not scalable from the known bulk materials could
+correspondingly arise. This can be particularly important for oxidation
+catalysis, where technologically relevant gas phase conditions are typically
+quite oxygen-rich. In such environments surface oxides may even form naturally
+in the induction period, and actuate then the reactive steady-state behavior
+that has traditionally been ascribed to the metal substrates. Corresponding
+aspects are reviewed by focusing on recent progress in the modeling and
+understanding of the oxidation behavior of late TMs, using particularly the
+late 4d series from Ru to Ag to discuss trends.",0409743v1
+2005-06-04,"Book Chapter 1: Theory of size, confinement and oxidation effect on oxide nanomaterials","Introduction bond-band-barrier (BOLS) correlation for the effect of
+electronic process of oxidation and the bond order-length-strengtrh (BOLS)
+correlation for the behaviour of nanostructures.",0506106v1
+2019-05-20,Effect of the degree of oxidation of graphene oxide on As(III) adsorption,"The study of the interaction between graphene oxide and arsenic is of great
+relevance towards the development of adsorbent materials and as a way to
+understand how these two materials interact in the environment. In this work we
+show that As(III) adsorption, primarily H3AsO3, by graphene oxide is dependent
+on its degree of oxidation. Variations in the concentration of potassium
+permanganate resulted in an increase on the C/O ratio from 1.98 to 1.35 with
+C-OH and C-O-C concentrations of 18 and 32%, respectively. Three oxidation
+degrees were studied, the less oxidized material reached a maximum As(III)
+adsorption capacity of 124 mg/g, whereas the graphene with the highest degree
+of oxidation reached a value of 288 mg/g at pH 7, to the authors knowledge, the
+highest reported in the literature. The interaction between graphene oxide and
+As(III) was also studied by Density Functional Theory (DFT) computer models
+showing that graphene oxide interacts with As(III) primarily through hydrogen
+bonds, having interaction energies with the hydroxyl and epoxide groups of 378
+and 361 kcal/mol, respectively. Finally, cytotoxicity tests showed that the
+graphene oxide had a cellular viability of 57% with 50 {\mu}g/ml, regardless of
+its degree of oxidation.",1905.12168v1
+2020-05-14,Simulating the fabrication of aluminium oxide tunnel junctions,"Aluminium oxide (AlO$_\mathrm{x}$) tunnel junctions are important components
+in a range of nanoelectric devices including superconducting qubits where they
+can be used as Josephson junctions. While many improvements in the
+reproducibility and reliability of qubits have been made possible through new
+circuit designs, there are still knowledge gaps in the relevant materials
+science. A better understanding of how fabrication conditions affect the
+density, uniformity, and elemental composition of the oxide barrier may lead to
+the development of lower noise and more reliable nanoelectronics and quantum
+computers. In this paper we use molecular dynamics to develop models of
+Al-AlO$_\mathrm{x}$-Al junctions by iteratively growing the structures with
+sequential calculations. With this approach we can see how the surface oxide
+grows and changes during the oxidation simulation. Dynamic processes such as
+the evolution of a charge gradient across the oxide, the formation of holes in
+the oxide layer, and changes between amorphous and semi-crystalline phases are
+observed. Our results are widely in agreement with previous work including
+reported oxide densities, self-limiting of the oxidation, and increased
+crystallinity as the simulation temperature is raised. The encapsulation of the
+oxide with metal evaporation is also studied atom by atom. Low density regions
+at the metal-oxide interfaces are a common feature in the final junction
+structures which persists for different oxidation parameters, empirical
+potentials, and crystal orientations of the aluminium substrate.",2005.06687v2
+2021-03-08,Understanding the role of exchange and correlations in complex oxides under strain and oxide heterostructures,"The study of complex oxides and oxide heterostructures have dominated the
+field of experimental and theoretical condensed matter research for the better
+part of the last few decades. Powerful experimental techniques like molecular
+beam epitaxy and pulsed laser deposition have made fabrication of oxide
+heterostructures with atomically sharp interfaces possible, while more and more
+sophisticated handling of exchange and correlations within first principles
+methods including density functional theory (DFT) supplemented with Hubbard U
+corrections and hybrid functionals, and beyond DFT techniques like dynamical
+mean field theory (DMFT) have made understanding of such correlated oxides and
+oxide interfaces easier. The emergence of the high mobility two dimensional
+electron gas with fascinating properties like giant photoconductance, large
+negative magnetoresistance, superconductivity, ferromagnetism, and the
+mysterious coexistence of the latter two have indeed caught the attention of
+condensed matter community at large. Similarly strain tuning of oxides have
+generated considerable interest particularly after the recent discovery of
+piezoelectric methods of strain generation. Theoretical understanding and
+prediction of the possible exotic phases emerging in such complex oxides both
+under strain and in heterostructures will eventually lead to better design of
+device applications in this new emerging field of oxide electronics, along with
+possible discovery of exotic physics in condensed matter systems which may be
+of wider significance! In this review we briefly look at theoretical studies of
+novel phenomena in oxides under strain and oxide heterostructures, and try to
+understand the role of exchange and particularly correlation in giving rise to
+such exotic electronic states.",2103.04943v1
+2021-05-21,Vanadium Dioxide Thin Films Synthesized Using Low Thermal Budget Atmospheric Oxidation,"Vanadium dioxide is a complex oxide material, which shows large resistivity
+and optical reflectance change while transitioning from the insulator to metal
+phase at ~68 {\deg}C. In this work, we use a modified atmospheric thermal
+oxidation method to oxidize RF-sputtered Vanadium films. Structural,
+surface-morphology and phase-transition properties of the oxidized films as a
+function of oxidation duration are presented. Phase-pure VO2 films are obtained
+by oxidizing ~130 nm Vanadium films in short oxidation duration of ~30 seconds.
+Compared to previous reports on VO2 synthesis using atmospheric oxidation of
+Vanadium films of similar thickness, we obtain a reduction in oxidation
+duration by more than one order. Synthesized VO2 thin film shows resistance
+switching of ~3 orders of magnitude. We demonstrate optical reflectance
+switching in long-wave infrared wavelengths in VO2 films synthesized using
+atmospheric oxidation of Vanadium. The extracted refractive index of VO2 in the
+insulating and in the metallic phase is in good agreement with VO2 synthesized
+using other methods. The considerable reduction in oxidation time of VO2
+synthesis while retaining good resistance and optical switching properties will
+help in integration of VO2 in limited thermal budget processes, enabling
+further applications of this phase-transition material.",2105.10264v1
+2021-07-15,Color of Copper/Copper oxide,"Stochastic inhomogeneous oxidation is an inherent characteristic of copper
+(Cu), often hindering color tuning and bandgap engineering of oxides. Coherent
+control of the interface between metal and metal oxide remains unresolved. We
+demonstrate coherent propagation of an oxidation front in single-crystal Cu
+thin film to achieve a full-color spectrum for Cu by precisely controlling its
+oxide-layer thickness. Grain boundary-free and atomically flat films prepared
+by atomic-sputtering epitaxy allow tailoring of the oxide layer with an abrupt
+interface via heat treatment with a suppressed temperature gradient. Color
+tuning of nearly full-color RGB indices is realized by precise control of
+oxide-layer thickness; our samples covered ~50.4% of the sRGB color space. The
+color of copper/copper oxide is realized by the reconstruction of the
+quantitative yield color from oxide pigment (complex dielectric functions of
+Cu2O) and light-layer interference (reflectance spectra obtained from the
+Fresnel equations) to produce structural color. We further demonstrate
+laser-oxide lithography with micron-scale linewidth and depth through local
+phase transformation to oxides embedded in the metal, providing spacing
+necessary for semiconducting transport and optoelectronics functionality.",2107.07175v1
+2021-10-14,Three regimes in the tribo-oxidation of high purity copper at temperatures of up to 150 $^\circ$C,"Surface oxidation of high-purity copper is accelerated under tribological
+loading. Tribo-oxide formation at room temperature is associated with diffusion
+processes along defects, such as dislocations or grain boundaries. Here, we
+embark on investigating the additional influence of temperature on the
+tribo-oxidation of copper. Dry, reciprocating sliding tests were performed with
+a variation of the sample temperature between 21 - 150 $^\circ$C.
+Microstructural changes were monitored and analyzed with state-of-the-art
+electron microscopy techniques. Oxide layer formation through thermal oxidation
+was observed for 150 $^\circ$C, but not for lower temperatures. As the
+temperature increases from room temperature up to 100 $^\circ$C, a
+significantly stronger tribo-oxidation into deeper material layers and an
+increase in the amount of formed pores and oxides was detected. Up to 75
+$^\circ$C, diffusional processes along grain boundaries and dislocation pipes
+were identified. Starting at 100 $^\circ$C, CuO was detected. Hence,
+tribological loading significantly alters the CuO formation in comparison with
+static oxidation. Along with the CuO formation at temperatures >= 90 $^\circ$C,
+the oxide layer thickness decreased while the friction coefficient increased.
+The observations broaden our understanding of the elementary mechanisms of
+tribo-oxidation in high-purity copper. Eventually, this will allow to
+systematically customize surfaces showing tribo-oxidation for specific
+tribological applications.",2110.07260v1
+2022-10-09,Probing the microscopic structure and flexibility of oxidized DNA by molecular simulations,"The oxidative damage of DNA is a compelling issue in molecular biophysics as
+it plays a vital role in the epigenetic control of gene expression and is
+believed to be associated with mutagenesis, carcinogenesis, and ageing. To
+understand the microscopic structural changes in physical properties of DNA and
+the resulting influence on its function due to oxidative damage of its
+nucleotide bases, we have conducted all-atom molecular dynamic simulations of
+double-stranded DNA (dsDNA) with its guanine bases being oxidized. The guanine
+bases are more prone to oxidative damage due to the lowest value of redox
+potential among all nucleobases. We have analyzed the local as well as global
+mechanical properties of native and oxidized dsDNA and explained those results
+by microscopic structural parameters and thermodynamic calculations. Our
+results show that the oxidative damage of dsDNA does not deform the
+Watson-Crick geometry; instead, the oxidized DNA structures are found to be
+better stabilized through electrostatic interactions. Moreover, oxidative
+damage changes the mechanical, helical, and groove parameters of dsDNA. The
+persistence length, stretch modulus, and torsional stiffness are found to be
+48.87 nm, 1239.26 pN, and 477.30 pN.nm^2, respectively, for native dsDNA, and
+these values are 61.31 nm, 659.91 pN, and 407.79 pN.nm^2, respectively, when
+all the guanine bases of the dsDNA are oxidized. Compared to the global
+mechanical properties, the changes in helical and groove properties are found
+to be more prominent, concentrated locally at the oxidation sites, and causing
+the transition of the backbone conformations from BI to BII at the regions of
+oxidative damage.",2210.04235v1
+2014-09-01,Phosphorene Oxide: Stability and electronic properties of a novel 2D material,"Phosphorene, the monolayer form of the (black) phosphorus, was recently
+exfoliated from its bulk counterpart. Phosphorene oxide, by analogy to graphene
+oxide, is expected to have novel chemical and electronic properties, and may
+provide an alternative route to synthesis of phosphorene. In this letter, we
+investigate physical and chemical properties of the phosphorene oxide including
+its formation by the oxygen adsorption on the bare phosphorene. Analysis of the
+phonon dispersion curves finds stoichiometric and non-stoichiometric oxide
+configurations to be stable at ambient conditions, thus suggesting that the
+oxygen absorption may not degrade the phosphorene. The nature of the band gap
+of the oxides depends on the degree of the functionalization of phosphorene;
+indirect gap is predicted for the non-stoichiometric configurations whereas a
+direct gap is predicted for the stoichiometric oxide. Application of the
+mechanical strain and external electric field leads to tunability of the band
+gap of the phosphorene oxide. In contrast to the case of the bare phosphorene,
+dependence of the diode-like asymmetric current-voltage response on the degree
+of stoichiometry is predicted for the phosphorene oxide.",1409.0459v2
+2014-10-15,Phosphorene oxides: bandgap engineering of phosphorene by oxidation,"We show that oxidation of phosphorene can lead to the formation of a new
+family of planar (2D) and tubular (1D) oxides and sub-oxides, most of them
+insulating. This confers to black phosphorus a native oxide that can be used as
+barrier material and protective layer. Further, the bandgap of phosphorene
+oxides depends on the oxygen concentration, suggesting that controlled
+oxidation can be used as a means to engineer the bandgap. For the oxygen
+saturated composition, P$_2$O$_5$, both the planar and tubular phases have a
+large bandgap energy of about 8.5eV, and are transparent in the near UV. These
+two forms of phosphorene oxides are predicted to have the same formation
+enthalpy as o$^\prime$-P$_2$O$_5$, the most stable of the previously known
+forms of phosphorus pentoxide.",1410.3906v1
+2014-11-05,Oxidation of graphite surface: the role of water,"Based on density functional calculations, we demonstrate a significant
+difference in oxidation patterns between graphene and graphite and the
+formation of defects after oxidation. Step-by-step modeling demonstrates that
+oxidation of 80% of the graphite surface is favorable. Oxidation above half of
+the graphite surface significantly decreases the energy costs of vacancy
+formation with CO2 production. The presence of water is crucial in the
+transformation of epoxy groups to hydroxyl, the intercalation with further
+bundle and exfoliation. In water-rich conditions, water intercalates graphite
+at the initial stages of oxidation and oxidation, which is similar to the
+oxidation process of free-standing graphene; in contrast, in water-free
+conditions, large molecules intercalate graphite only after oxidation occurs on
+more than half of the surface.",1411.1143v1
+2019-09-30,Mechanically prepared copper surface in oxidizing and non-oxidizing conditions,"In the present work surface roughness of copper samples after mechanical
+surface preparation processes (polishing, grinding, sand-blasting) and after
+exposure in non-oxidizing (high purity argon) and oxidizing (air) conditions at
+700 and 750{\deg}C have been evaluated by contact profilometer and by fractal
+analysis. Quantitative description of surfaces that are hidden from the sight
+of conventional methods is possible by fractal analysis, e.g. in the present
+work, the roughness of Cu2O/Cu boundary has been evaluated under oxide layer.
+It has been pointed out, that in both oxidizing and non-oxidizing conditions
+initial surface roughness of copper is affected by annealing at high
+temperature: at 700{\deg}C surface roughness of polished and ground samples
+increased but at 750{\deg}C decreased in comparison to surface roughness prior
+to heat treatment. For sand-blasted samples in both oxidizing and non-oxidizing
+conditions the lowest values of surface roughness parameters were obtained at
+750{\deg}C. It is then concluded that two phenomena are responsible for such
+effect: chemical reaction between copper and oxygen and surface diffusion of
+copper due to high temperature of annealing.",1909.13645v2
+2020-01-24,Passivation mechanisms and pre-oxidation effects on model surfaces of FeCrNi austenitic stainless steel,"Passivation mechanisms were investigated on (100)-oriented Fe-18Cr-13Ni
+surfaces with direct transfer between surface preparation and analysis by X-ray
+photoelectron spectroscopy and scanning tunneling microscopy and
+electrochemical characterization. Starting from oxide-free surfaces,
+pre-oxidation at saturation under ultra-low pressure (ULP) oxygen markedly
+promotes the oxide film Cr(III) enrichment and hinders/delays subsequent iron
+oxidation in water-containing environment. Exposure to sulfuric acid at open
+circuit potential causes preferential dissolution of oxidized iron species.
+Anodic passivation forces oxide film re-growth, Cr(III) dehydroxylation and
+further enrichment. ULP pre-oxidation promotes Cr(III) hydroxide formation at
+open circuit potential, compactness of the nanogranular oxide film and
+corrosion protection.",2001.09025v1
+2017-05-07,Remarkably strong chemisorption of nitric oxide on insulating oxide films promoted by hybrid structure,"The remarkably strong chemical adsorption behaviors of nitric oxide on
+magnesia (001) film deposited on metal substrate have been investigated by
+employing periodic density functional calculations with Van der Waals
+corrections. The molybdenum supported magnesia (001) show significantly
+enhanced adsorption properties and the nitric oxide is chemisorbed strongly and
+preferably trapped in flat adsorption configuration on metal supported oxide
+film, due to the substantially large adsorption energies and transformation
+barriers. The analysis of Bader charges, projected density of states,
+differential charge densities, electron localization function, highest occupied
+orbital and particular orbital with largest Mg-NO-Mg bonding coefficients, are
+applied to reveal the electronic adsorption properties and characteristics of
+bonding between nitric oxide and surface as well as the bonding within the
+hybrid structure. The strong chemical binding of nitric oxide on magnesia
+deposited on molybdenum slab offers new opportunities for toxic gas detection
+and treatment. We anticipate that hybrid structure promoted remarkable chemical
+adsorption of nitric oxide on magnesia in this study will provide versatile
+strategy for enhancing chemical reactivity and properties of insulating oxide.",1705.02590v1
+2018-08-02,A Generalized Mathematical Framework for Thermal Oxidation Kinetics,"We present a generalized mathematical model for thermal oxidation and the
+growth kinetics of oxide films. The model expands long-standing classical
+models by taking into account the reaction occurring at the interface as well
+as transport processes in greater details. The standard Deal-Grove model (the
+linear-parabolic rate law) relies on the assumption of quasi-static diffusion
+that results in a linear concentration profile of, for example, oxidant species
+in the oxide layer. By relaxing this assumption and resolving the entire
+problem, three regimes can be clearly identified corresponding to different
+stages of oxidation. Namely, the oxidation starts with the reaction-controlled
+regime (described by a linear rate law), is followed by a transitional regime
+(described by a logarithmic or power law depending on the stoichiometry
+coefficient m), and ends with the well known diffusion-controlled regime
+(described by a parabolic rate law). Deal-Grove's theory is shown to be the
+lower order approximation of the proposed model. Various oxidation rate laws
+are unified into a single model to describe the entire oxidation process.",1808.00916v1
+2020-10-11,Electrical properties of thermal oxide scales on pure iron in liquid lead-bismuth eutectic,"The impedance behavior of pre-oxidized iron in liquid lead-bismuth eutectic
+(LBE) at 200 oC is studied using electrochemical impedance spectroscopy. The
+structures and resistance of oxide grown on iron oxidized in air at different
+temperatures and durations are compared. The results show that the resistance
+of the oxide film increases with increasing oxidizing temperature, due to the
+formation of a thicker scale and fewer defects. At the same temperature (600
+oC), increasing the oxidation time can also reduce the defect concentration in
+the oxide film and improve the impedance of the oxide scale in LBE.",2010.05372v1
+2020-11-17,Effect of Surface Treatment on High-Temperature Oxidation Behavior of IN 713C,"The effects of surface preparations on oxidation kinetics and oxide scale
+morphology for the commercially available Ni-based superalloy IN 713C have been
+investigated. The ground and polished samples were exposed in air at 800-1100C.
+The ground specimens were found to demonstrate lower oxidation kinetics
+compared to those after polishing. The grinding also affected the oxide scale
+morphology, resulting in a protective alumina scale, while the polished samples
+developed Ni-/Cr-rich mixed oxides on the surface. Better oxidation resistance
+of the ground surfaces is related to a higher concentration of defects in the
+nearsurface region introduced by cold working. These defects facilitate the
+outward transport of the scaleforming element Al and thus are beneficial for
+protective oxidation. The oxidation mechanism at lower temperatures was
+introduced. The model based on the generalized Darken method and multiphase
+approximation was proposed.",2011.08910v1
+2022-01-11,Oxide-stabilized microstructure of severe plastically deformed CuCo alloys,"Nanocrystalline materials are well known for their beneficial mechanical and
+physical properties. However, it is of utmost importance to stabilize the
+microstructure at elevated temperatures to broaden the window of application
+e.g. by pinning grain boundaries through impurities or oxides. CuCo alloys,
+severe plastically deformed using high-pressure torsion, were used to
+investigate the evolution of oxides upon annealing. These investigations were
+performed using electron microscopy, synchrotron high-energy X-ray scattering
+and atom probe tomography. Monitoring the evolution of oxides by in-situ small
+angle scattering investigations indicates the growth of primary oxides as well
+as the formation of another species of oxide at elevated temperatures. Slightly
+different coarsening can be observed in heat-treated samples, which can be
+traced back to the influence of different oxide amounts. The initially
+supersaturated CuCo matrix changes by the decomposition process as well as Co-
+and Cu-based oxides formation and growth. It has been found that the major
+number of oxides which are present after annealing, can already be found in the
+starting materials.",2201.03900v1
+1995-05-03,Magnetic and Transport Properties of the Kondo Lattice Model with Ferromagnetic Exchange Coupling,"The Kondo lattice model with Hund's ferromagnetic spin coupling is
+investigated as a microscopic model of the perovskite-type $3d$ manganese oxide
+(R,A)MnO$_3$ where $R$ and $A$ are rare earth element and alkaline earth
+element, respectively. We take the classical spin limit $S=\infty$ for the
+simplicity of the calculation, since the quantum exchange process seems to be
+irrelevant in the high temperature paramagnetic phase. Magnetic and transport
+properties of the system are calculated. In the hole doped systems,
+ferromagnetic instabilities are observed as the temperature is lowered. The
+giant magnetoresistance of this model is in excellent agreement with the
+experimental data of (La,Sr)MnO$_3$.",9505011v3
+1998-02-03,Magnetic properties of the coupled ladder system MgV$_2$O$_5$,"We present magnetic susceptibility measurements on MgV$_2$O$_5$, a compound
+in which the vanadium oxide planes have the same topology as in CaV$_2$O$_5$.
+The most striking property is that there is an energy gap of about 15 K, much
+smaller than in CaV$_2$O$_5$, where the values reported are of the order of 500
+K. We show that this may be understood naturally in terms of the phase diagram
+of the frustrated, coupled ladder system. This analysis leads to the prediction
+that MgV$_2$O$_5$ should have incommensurate dynamic spin fluctuations.",9802029v1
+1998-04-17,High-Tc superconductivity through a charge pairing mechanism in a strongly coupled disordered phase,"We present a lattice field theory of spins coupled to Dirac fermions, as a
+model for the doped copper oxide compounds. Both the fermionic and spin degrees
+of freedom are treated dynamically. The influence of the charge carriers on the
+magnetic ordering follows automatically. The magnetic phase diagram at zero
+temperature is studied numerically and with Mean-Field methods. The Hybrid
+Monte Carlo algorithm is adapted to the O(3) non-linear sigma model constraint.
+The charged excitations in the various phases are studied at the Mean-Field
+level. Bound states of two charged fermions are found in a strongly coupled
+paramagnetic phase, without requiring a Fermi sea. We acquire a qualitative
+understanding of high-T$_c$ superconductivity through Bose-Einstein
+condensation of those dynamically bound pairs. The model also implies
+insulating behaviour at low doping, and Fermi liquid behaviour at large doping.
+We predict the possibility of reentrant superconductivity and the absence of
+superconductivity in spin-1 and spin-3/2 materials.",9804184v1
+1998-07-24,Destruction of localized electron pairs above the magnetic-field-driven superconductor-insulator transition in amorphous InO films,"We have investigated the field-induced superconductivity-destroying quantum
+transition in amorphous indium oxide films at low temperatures down to 30 mK.
+It has been found that, on the high-field side of the transition, the
+magnetoresistance reaches a maximum and the phase can be insulating as well as
+metallic. With further increasing magnetic field the film resistance drops and
+approaches in the high-field limit the resistance value at transition point so
+that at high fields the metallic phase occurs for both cases. We give a
+qualitative account of this behavior in terms of field-induced destruction of
+localized electron pairs.",9807332v2
+1999-02-11,Neutron Scattering Study of Spin Density Wave Order in the Superconducting State of Excess-Oxygen-Doped La2CuO4+y,"We report neutron scattering measurements of spin density wave order within
+the superconducting state of a single crystal of predominately stage-4
+La2CuO4+y with a Tc(onset) of 42 K. The low temperature elastic magnetic
+scattering is incommensurate with the lattice and is characterized by
+long-range order in the copper-oxide plane with the spin direction identical to
+that in the insulator. Between neighboring planes, the spins exhibit
+short-range correlations with a stacking arrangement reminiscent of that in the
+undoped antiferromagnetic insulator. The elastic magnetic peak intensity
+appears at the same temperature within the errors as the superconductivity,
+suggesting that the two phenomena are strongly correlated. These observations
+directly reveal the persistent influence of the antiferromagnetic order as the
+doping level increases from the insulator to the superconductor. In addition,
+our results confirm that spin density wave order for incommensurabilities near
+1/8 is a robust feature of the La2CuO4-based superconductors.",9902157v2
+1999-05-12,Phase diagram of an extended Kondo lattice model for manganites: the Schwinger-boson mean-field approach,"We investigate the phase diagram of an extended Kondo lattice model for doped
+manganese oxides in the presence of strong but finite Hund's coupling and
+on-site Coulomb interaction. By means of the Schwinger-boson mean-field
+approach, it is found that, besides magnetic ordering, there will be
+non-uniform charge distributions, such as charge ordering and phase separation,
+if the interaction between electrons prevails over the hybridization. Which of
+the charge ordering and phase separation appears is determined by a competition
+between effective repulsive and attractive interactions due to virtual
+processes of electron hopping. Calculated results show that strong electron
+correlations caused by the on-site Coulomb interaction as well as the finite
+Hund's coupling play an important role in the magnetic ordering and charge
+distribution at low temperatures.",9905152v1
+1999-10-28,Magnetic Properties of Weakly Doped Antiferromagnets,"We study the spin excitations and the transverse susceptibility of a
+two-dimensional antiferromagnet doped with a small concentration of holes in
+the t-J model. The motion of holes generates a renormalization of the magnetic
+properties. The Green's functions are calculated in the self-consistent Born
+approximation. It is shown that the long-wavelength spin waves are
+significantly softened and the shorter-wavelength spin waves become strongly
+damped as the doping increases. The spin wave velocity is reduced by the
+coherent motion of holes, and not increased as has been claimed elsewhere. The
+transverse susceptibility is found to increase considerably with doping, also
+as a result of coherent hole motion. Our results are in agreement with
+experimental data for the doped copper oxide superconductors.",9910474v1
+2000-03-17,Noise Probe of the Dynamic Phase Separation in La2/3Ca1/3MnO3,"Giant Random Telegraph Noise (RTN) in the resistance fluctuation of a
+macroscopic film of perovskite-type manganese oxide La2/3Ca1/3MnO3 has been
+observed at various temperatures ranging from 4K to 170K, well below the Curie
+temperature (TC = 210K). The amplitudes of the two-level-fluctuations (TLF)
+vary from 0.01% to 0.2%. We use a statistical analysis of the life-times of the
+TLF to gain insight into the microscopic electronic and magnetic state of this
+manganite. At low temperature (below 30K) The TLF is well described by a
+thermally activated two-level model. An estimate of the energy difference
+between the two states is inferred. At higher temperature (between 60K and
+170K) we observed critical effects of the temperature on the life-times of the
+TLF. We discuss this peculiar temperature dependence in terms of a sharp change
+in the free energy functional of the fluctuators. We attribute the origin of
+the RTN to be a dynamic mixed-phase percolative conduction process, where
+manganese clusters switch back and forth between two phases that differ in
+their conductivity and magnetization.",0003313v1
+2000-08-25,Random Berry Phase Magnetoresistance as a Probe of Interface Roughness in Si MOSFETs,"The effect of silicon-oxide interface roughness on the weak-localization
+magnetoconductance of a silicon MOSFET in a magnetic field, tilted with respect
+to the interface, is studied. It is shown that an electron picks up a random
+Berry's phase as it traverses a closed orbit. Effectively, due to roughness,
+the electron sees an uniform field parallel to the interface as a random
+perpendicular field. At zero parallel field the dependence of the conductance
+on the perpendicular field has a well known form, the weak-localization
+lineshape. Here the effect of applying a fixed parallel field on the lineshape
+is analyzed. Many types of behavior are found including homogeneous broadening,
+inhomogeneous broadening and a remarkable regime in which the change in
+lineshape depends only on the magnetic field, the two length scales that
+characterize the interface roughness and fundamental constants. Good agreement
+is obtained with experiments that are in the homogeneous broadening limit. The
+implications for using weak-localization magnetoconductance as a probe of
+interface roughness, as proposed by Wheeler and coworkers, are discussed.",0008375v1
+2001-06-04,Dzyaloshinski-Moriya Interaction in the 2D Spin Gap System SrCu2(BO3)2,"The Dzyaloshinski-Moriya interaction partially lifts the magnetic frustration
+of the spin-1/2 oxide SrCu2(BO3)2. It explains the fine structure of the
+excited triplet state and its unusual magnetic field dependence, as observed in
+previous ESR and new neutron inelastic scattering experiments. We claim that it
+is mainly responsible for the dispersion. We propose also a new mechanism for
+the observed ESR transitions forbidden by standard selection rules, that relies
+on an instantaneous Dzyaloshinski-Moriya interaction induced by spin-phonon
+couplings.",0106036v3
+2001-07-30,Martensitic accommodation strain and the metal-insulator transition in manganites,"In this paper, we report polarized optical microscopy and electrical
+transport studies of manganese oxides that reveal that the charge ordering
+transition in these compounds exhibits typical signatures of a martensitic
+transformation. We demonstrate that specific electronic properties of
+charge-ordered manganites stem from a combination of martensitic accommodation
+strain and effects of strong electron correlations. This intrinsic strain is
+strongly affected by the grain boundaries in ceramic samples. Consistently, our
+studies show a remarkable enhancement of low field magnetoresistance and the
+grain size effect on the resistivity in polycrystalline samples and suggest
+that the transport properties of this class of manganites are governed by the
+charge-disordered insulating phase stabilized at low temperature by virtue of
+martensitic accommodation strain. High sensitivity of this phase to strains and
+magnetic field leads to a variety of striking phenomena, such as unusually high
+magnetoresistance (10^10 %) in low magnetic fields.",0107609v1
+2001-11-05,Microscopic Magnetic Properties of (V$_{1-x}$Ti$_{x}$)$_2$O$_3$ near the Phase Boundary of the Metal-Insulator Transition,"Magnetic susceptibility (chi) and $^{51}$V NMR have been measured in
+(V$_{1-x}$Ti$_{x}$)$_2$O$_3$ near the phase boundary of the metal-insulator
+transition. It is established that the transition from antiferromagnetic
+insulating (AFI) to antiferromagnetic metallic phases near $x_{\rm c}\approx
+0.05$ is not quantum critical but is discontinuous with a jump of the
+transition temperature. In the AFI phase at 4.2 K, we observed the satellite in
+the zero-field $^{51}$V NMR spectrum around 181 MHz in addition to the ``host''
+resonance around 203 MHz. The satellite is also observable in the paramagnetic
+metallic phase of the x = 0.055 sample. We associated the satellite with the V
+sites near Ti which are in the V$^{3+}$-like oxidation state but has different
+temperature dependence of the NMR shift from that of the host V site. The host
+d-spin susceptibility for x = 0.055 decreases below $\sim$60 K but remains
+finite in the low-temperature limit.",0111059v2
+2001-11-10,"Temperature Dependence of the Magnetic Penetration Depth in the Vortex State of the Pyrochlore Superconductor, Cd2Re2O7","We report transverse field and zero field muon spin rotation studies of the
+superconducting rhenium oxide pyrochlore, Cd2Re2O7. Transverse field
+measurements (H=0.007 T) show line broadening below Tc, which is characteristic
+of a vortex state, demonstrating conclusively the type-II nature of this
+superconductor. The penetration depth is seen to level off below about 400 mK
+(T/Tc~0.4), with a rather large value of lambda (T=0)~7500A. The temperature
+independent behavior below ~ 400 mK is consistent with a nodeless
+superconducting energy gap. Zero-field measurements indicate no static magnetic
+fields developing below the transition temperature.",0111187v1
+2001-11-10,Detailed Structure of the Magnetic Excitation Spectra of YBa2Cu3Oy and Its Implication on the Physical Characteristics of the Electron System,"Detailed structure of the magnetic excitation spectra x""(q,w) of the
+superconducting oxide YBa2Cu3O6.5(the transition temperature Tc ~ 52 K) in the
+wave vector (q)- and the energy(w)-space, and its temperature (T) dependence
+have been studied. By adopting an effective energy dispersion of the quasi
+particles which can reproduce the shape of the Fermi surface and by introducing
+the exchange interaction between the Cu spins, a rather satisfactory agreement
+between the calculation and the experimentally observed data can be obtained.
+In the study, it has been found that the effects of the quasi particle- energy
+broadening on the excitation spectra x""(q,w) is important. The sharp resonance
+peak observed at w ~ 40 meV for the optimally doped system of YBa2Cu3Oy can be
+naturally reproduced by the present model",0111190v3
+2002-01-15,Structural and Magnetic Instabilities of La$_{2-x}$Sr$_x$CaCu$_2$O$_6$,"A neutron scattering study of nonsuperconducting
+La$_{2-x}$Sr$_x$CaCu$_2$O$_6$ (x=0 and 0.2), a bilayer copper oxide without CuO
+chains, has revealed an unexpected tetragonal-to-orthorhombic transition with a
+doping dependent transition temperature. The predominant structural
+modification below the transition is an in-plane shift of the apical oxygen. In
+the doped sample, the orthorhombic superstructure is strongly disordered, and a
+glassy state involving both magnetic and structural degrees of freedom develops
+at low temperature. The spin correlations are commensurate.",0201253v2
+2002-03-11,Pressure dependence of phase transitions in the quasi one-dimensional metal-insulator transition system beta-Na1/3V2O5,"The pressure dependence of phase transitions in the quasi one-dimensional
+vanadium oxide $\beta$-Na$_{1/3}$V$_2$O$_5$ has been studied by magnetic
+susceptibility and electrical resistivity measurements. The pressure dependence
+of the various transition temperatures is quite differently. The transition at
+T=240 K, previously reported and attributed to ordering on Na sites, and a
+second transition at $T \approx 222$ K, reported here for the first time and
+attributed to a further increase of order on Na sites, are almost independent
+of pressure. On the other hand, the metal-insulator (MI) transition at
+$T_{MI}=130$ K shifts to lower temperatures, while the magnetic transition at
+$T_N=24$ K shifts to higher temperatures with increasing pressure. We discuss
+the different pressure dependencies of $T_{MI}$ and $T_N$ in terms of
+increasing interchain coupling and the MI transition to be of Peierls type.",0203234v1
+2002-08-09,"On the nature of ferromagnetism in diluted magnetic semiconductors: GaAs:Mn, GaP:Mn","A microscopic Hamiltonian for interacting manganese impurities in diluted
+magnetic semiconductors (DMS) is derived. It is shown that in p -type III-V DMS
+the indirect exchange between Mn impurities has similarities with the Zener
+mechanism in transition metal oxides. Here the mobile holes and localized
+states near the top of the valence band play the role of unoccupied oxygen
+orbitals which induce ferromagnetism. The Curie temperature estimated from the
+proposed kinematic exchange agrees with recent experiments on GaAs:Mn. The
+model is also applicable to the GaP:Mn system.",0208188v1
+2002-08-28,Orbital state and magnetic properties of LiV_2 O_4,"LiV_2 O_4 is one of the most puzzling compounds among transition metal oxides
+because of its heavy fermion like behavior at low temperatures. In this paper
+we present results for the orbital state and magnetic properties of LiV_2 O_4
+obtained from a combination of density functional theory within the local
+density approximation and dynamical mean-field theory (DMFT). The DMFT
+equations are solved by quantum Monte Carlo simulations. The trigonal crystal
+field splits the V 3d orbitals such that the a_{1g} and e_{g}^{pi} orbitals
+cross the Fermi level, with the former being slightly lower in energy and
+narrower in bandwidth. In this situation, the d-d Coulomb interaction leads to
+an almost localization of one electron per V ion in the a_{1g} orbital, while
+the e_{g}^{pi} orbitals form relatively broad bands with 1/8 filling. 2The
+theoretical high-temperature paramagnetic susceptibility chi(T) follows a
+Curie-Weiss law with an effective paramagnetic moment p_{eff}=1.65 in agreement
+with the experimental results.",0208547v1
+2002-08-30,Nickel Antidot Arrays on Anodic Alumina Substrates,"Large area nickel antidot arrays with density up to 10^10 /cm^2 have been
+fabricated by depositing nickel onto anodic aluminum oxide membranes that
+contain lattices of nanopores. Electron microscopy images show a high degree of
+order of the antidot arrays. Various sizes and shapes of the antidots were
+observed with increasing thickness of the deposited nickel. New features appear
+in the antidot arrays in both magnetization and transport measurements when the
+external magnetic field is parallel to the current direction, including an
+enhancement and a nonmonotonous field dependence of the magnetoresistance,
+larger values of the coercive field and remanence moment, and smaller
+saturation field.",0208608v2
+2002-11-15,Specific Heat of Kagome Ice in the Pyrochlore Oxide Dy2Ti2O7,"A novel macroscopically degenerate state called kagome ice, which was
+recently found in a spin ice compound Dy2Ti2O7 in a magnetic field applied
+along the [111] direction of the cubic unit cell, is studied by specific heat
+measurements. The residual entropy of the kagome ice is estimated to be 0.65
+J/K mol Dy, which is nearly 40 % of that for the tetrahedral spin ice obtained
+in a zero field (1.68 J/K mol Dy) and is in good agreement with a theoretical
+prediction. It is also reported that the kagom ice state, which is stabilized
+at a range of magnetic field of 0.3 ~ 0.6 T, is a 'gas' phase and condenses
+into a 'liquid' phase with nearly zero entropy at a critical field of 1 T.",0211326v1
+2002-11-27,Theory of dopants and defects in Co-doped TiO2 anatase,"We report first-principles microscopic calculations of the formation energy,
+electrical activity, and magnetic moment of Co dopants and a variety of native
+defects in TiO2 anatase. Using these results, we use equilibrium thermodynamics
+to predict the resulting carrier concentration, the average magnetic moment per
+Co, and the dominant oxidation state of Co. The predicted values are in good
+agreement with experiment under the assumption of O-poor growth conditions. In
+this regime, a substantial fraction of Co dopants occupy interstitial sites as
+donors. The incomplete compensation of these donors by substitutional Co
+acceptors then leads to n-type behavior, as observed experimentally.",0211614v2
+2003-01-14,Griffiths singularities and magnetoresistive manganites,"The large, so-called colossal, magnetoresistivity of doped manganese oxides
+based on LaMnO3 has attracted considerable attention, but only one unusual
+feature of the ferromagnetic transition in these compounds. We examine in this
+paper the progression of magnetic and thermodynamic behavior as the transition
+temperature is made to vary from 360 K to 218 K by changing the divalent
+dopant. Single crystals of La_{0.7}Sr_{0.3}MnO3, as is well known, show modest
+magnetoresistivity and conventional critical behavior. La$_{0.7}$Pb$_{0.3}$
+Mn$O_3$, and to an even greater extent, La$_{0.7}$Ca$_{0.3}$MnO$_3$, have
+unusual magnetic properties extending more than 100 K above the transition. We
+treat the properties of the latter samples in the context of a Griffiths phase
+in which the transition temperature is depressed from its maximum value T_{G}
+by random bond-angle bending.",0301243v1
+2003-02-21,Spin-Glass-like Transition and Hall Resistivity of Y2-xBixIr2O7,"Various physical properties of the pyrochlore oxide Y2-xBixIr2O7 have been
+studied. The magnetizations M measured under the conditions of the
+zero-field-cooling(ZFC) and the field-cooling(FC) have different values below
+the temperature T=TG. The anomalous T-dependence of the electrical
+resistivities r and the thermoelectric powers S observed at around TG indicates
+that the behavior of the magnetization is due to the transition to the state
+with the spin freezing. In this spin-frozen state, the Hall resistivities rH
+measured with the ZFC and FC conditions are found to have different values,
+too, in the low temperature phase (T<TG). Possible mechanisms which induce such
+the hysteretic behavior are discussed.",0302437v1
+2003-07-18,Structures and electromagnetic properties of the A-site ordered/disordered manganites; RBaMn2O6/R0.5Ba0.5MnO3 (R = Y and rare earth elements),"The discovery of novel structural and physical properties in the $A$-site
+ordered manganite $R$BaMn$_2$O$_6$ ($R$ = Y and rare earth elements) has
+demanded new comprehension about perovskite manganese oxides. In the present
+study, the $A$-site disordered form $R$$_{0.5}$Ba$_{0.5}$MnO$_3$ was
+successfully synthesized and compared with $R$BaMn$_2$O$_6$ in the structures
+and electromagnetic properties. $R$$_{0.5}$Ba$_{0.5}$MnO$_3$ has a primitive
+cubic perovskite cell. Unexpectedly the magnetic glassy states are dominant as
+the ground state for $R$$_{0.5}$Ba$_{0.5}$MnO$_3$. A peculiar behavior, the
+steplike ultrasharp magnetization and resistivity change, has been observed in
+Pr$_{0.5}$Ba$_{0.5}$MnO$_3$.",0307456v1
+2003-08-19,Unconventional Charge Ordering in Na0.70CoO2 below 300 K,"We present the results of measurements of the dc-magnetic susceptibility
+chi(T) and the 23Na-NMR response of Na_{0.70}CoO_{2} at temperatures between 50
+and 340 K. The chi(T) data suggest that for T > 75 K, the Co ions adopt an
+effective configuration of Co^{3.4+}. The 23Na-NMR response reveals pronounced
+anomalies near 250 and 295 K, but no evidence for magnetic phase transitions is
+found in chi(T). Our data suggest the onset of a dramatic change in the Co
+3d-electron spin dynamics at 295 K. This process is completed at 230 K. Our
+results maybe interpreted as evidence for either a tendency to electron
+localization or an unconventional charge-density wave phenomenon within the
+cobalt oxide layer, CoO_2, 3d electron system near room temperature.",0308383v2
+2003-12-16,Magnetoresistive study of antiferromagnetic--weak ferromagnetic transition in single-crystal La$_{2}$CuO$_{4+δ}$,"The resistive measurements were made to study the magnetic field-induced
+antiferromagnetic (AF) - weak ferromagnetic (WF) transition in La$_2$CuO$_4$
+single-crystal. The magnetic field (DC or pulsed) was applied normally to the
+CuO$_2$ layers. The transition manifested itself in a drastic decrease of the
+resistance in critical fields of ~5-7 T. The study is the first to display the
+effect of the AF -WF transition on the conductivity of the La$_2$CuO$_4$
+single-crystal in the parallel - to - CuO$_2$ layers direction. The results
+provide support for the 3-dimensional nature of the hopping conduction of this
+layered oxide.",0312409v1
+2004-01-08,Orbital degeneracy as a source of frustration in LiNiO$_2$,"Motivated by the absence of cooperative Jahn-Teller effect and of magnetic
+ordering in LiNiO$_2$, a layered oxide with triangular planes, we study a
+general spin-orbital model on the triangular lattice. A mean-field approach
+reveals the presence of several singlet phases between the SU(4) symmetric
+point and a ferromagnetic phase, a conclusion supported by exact
+diagonalizations of finite clusters. We argue that one of the phases,
+characterized by a large number of low-lying singlets associated to dimer
+coverings of the triangular lattice, could explain the properties of LiNiO$_2$,
+while a ferro-orbital phase that lies nearby in parameter space leads to a new
+prediction for the magnetic properties of NaNiO$_2$.",0401122v2
+2004-01-30,Magnetoelectric Effects in Ferromagnetic Metal-Piezoelectric Oxide Layered Structures,"Frequency dependence of magnetoelectric (ME) coupling is investigated in
+trilayers of ferromagnetic alloy and piezoelectric lead zirconate titanate
+(PZT). The ferromagnetic phases studied include permendur, a soft magnet with
+high magnetostriction, iron, nickel, and cobalt. Low frequency data on ME
+voltage coefficient versus bias magnetic field indicate strong coupling only
+for trilayers with permendure or Ni. Measurements of frequency dependence of ME
+voltage reveal a giant ME coupling at electromechanical resonance. The ME
+interactions for transverse fields is an order of magnitude stronger than for
+longitudinal fields. The maximum voltage coefficient of 90 V/cm Oe at resonance
+is measured for samples with nickel or permendure and is three orders of
+magnitude higher than low-frequency values.",0401648v1
+2004-03-01,Unconventional superconductivity in Na$_{0.35}$CoO$_{2}\cdot$1.3D$_{2}$O and proximity to a magnetically ordered phase,"Muon spin relaxation ($\mu$SR) measurements on the new layered cobalt oxide
+superconductor Na$_{0.35}$CoO$_{2}\cdot$1.3H$_{2}$O and its parent,
+non-superconducting compounds, have revealed unconventional nature of
+superconductivity through: (1) a small superfluid energy which implies a
+surprisingly high effective mass of the charge carriers, approximately 100
+times the bare electron mass; (2) the superconducting transition temperature
+$T_{c}$ scaling with the superfluid energy following the correlations found in
+high-$T_{c}$ cuprate and some other two-dimensional superconductors; (3) an
+anisotropic pairing without broken time-reversal symmetry; and (4) the
+proximity of a magnetically ordered insulating phase at Na$_{0.5}$CoO$_{2}$
+below $T_{N}$ = 53 K.",0403031v1
+2004-08-17,Two-Dimensional Geometry of Spin Excitations in the High Temperature Superconductor YBa2Cu3O6+x,"The fundamental building block of the copper oxide superconductors is a Cu4O4
+square plaquette. In most of these materials, the plaquettes are slightly
+distorted and form a rectangular lattice. An influential theory predicts that
+high-temperature superconductivity is nucleated in ""stripes"" aligned along one
+of the axes of this lattice. This theory had received strong support from
+experiments that appeared to indicate a one-dimensional character of the
+magnetic excitations in the high temperature superconductor YBa2Cu3O6.6. Here
+we report neutron scattering data on ""untwinned"" YBa2Cu3O6+x crystals, in which
+the orientation of the rectangular lattice is maintained throughout the entire
+volume. Contrary to the earlier claim, we demonstrate that the geometry of the
+magnetic fluctuations is two-dimensional. Rigid stripe arrays therefore appear
+to be ruled out over a wide range of doping levels in YBa2Cu3O6+x, but the data
+may be consistent with liquid-crystalline stripe order.",0408379v1
+2004-08-24,Interfacial strain measurements in $SrRuO_3/SrMnO_3$ magnetic multilayers,"Magnetic multilayers of $(SrRuO_3)_m(SrMnO_3)_n$ were grown artificially
+using the pulsed laser deposition technique on (001)-oriented $SrTiO_3$
+substrates. The state of strain at the interfaces and the structural coherency
+are studied in details utilizing asymmetrical $X$-ray diffraction and the $\sin
+^2\psi $ method. First, the evolution of the lattice parameters, the
+crystallinity and the epitaxy of the films are evaluated as a function of the
+number of $SrMnO_3$ unit cells using $X$-rays diffraction and transmission
+electron microscopy. Second, our results on the stress indicate that the
+$SrRuO_3/SrMnO_3$ superlattices show a larger residual strain as compared to
+the single layer film of $SrRuO_3$. This suggests that the lattice stiffening
+from interfacial strain and inhibiting the dislocation by composition
+modulation. Finally, these results bring insights on the interfacial stress
+measurements of oxide multilayers that can be used to control the physical
+properties at the level of the atomic scale.",0408513v1
+2004-10-27,Matrix Assisted Formation of Ferrihydrite Nanoparticles in a Siloxane/Poly(Oxyethylene) Nanohybrid,"Matrix-assisted formation of ferrihydrite, an iron oxide hydroxide analogue
+of the protein ferritin-core, in a sol-gel derived organic-inorganic hybrid is
+reported. The hybrid network (named di-ureasil) is composed of
+poly(oxyethylene) chains of different average polymer molecular weights grafted
+to siloxane domains by means of urea cross-linkages and accommodates
+ferrihydrite nanoparticles. Magnetic measurements, Fourier transform infrared
+and nuclear magnetic resonance spectroscopy reveal that the controlled
+modification of the polymer molecular weight allows the fine-tuning of the
+ability of the hybrid matrix to assist and promote iron coordination at the
+organic-inorganic interface and subsequent nucleation and growth of the
+ferrihydrite nanoparticles whose core size (2-4 nm) is tuned by the amount of
+iron incorporated. The polymer chain length, its arrangement and crystallinity,
+are key factors on the anchoring and formation of the ferrihydrite particles.",0410695v1
+2004-10-28,"High-pressure synthesis, crystal structure determination, and a Ca substitution study of the metallic rhodium oxide NaRh2O4","The sodium rhodate NaRh2O4 was synthesized for the first time and
+characterized by neutron and x-ray diffraction studies, measurements of
+magnetic susceptibility, specific heat, electrical resistivity, and the Seebeck
+coefficient. NaRh2O4 crystallizes in the CaFe2O4-type structure, which is
+comprised of a characteristic RhO6 octahedra network. The compound is metallic
+in nature, probably reflecting the 1 to 1 mixed valence character of Rh(III)
+and Rh(IV) in the network. For further studies of the compound, the Rh valence
+was varied significantly by means of an aliovalent substitution: the full range
+solid solution between NaRh2O4 and CaRh2O4 was achieved and characterized as
+well. The metallic state was dramatically altered, and a peculiar magnetism
+developed in the low Na concentration range.",0410742v1
+2004-11-26,Room-temperature ferromagnetism in Sr_(1-x)Y_xCoO_(3-delta) (0.2 < x < 0.25),"We have measured magnetic susceptibility and resistivity of
+Sr$_{1-x}$Y$_x$CoO$_{3-\delta}$ ($x=$ 0.1, 0.15, 0.2, 0.215, 0.225, 0.25, 0.3,
+and 0.4), and have found that Sr$_{1-x}$Y$_x$CoO$_{3-\delta}$ is a room
+temperature ferromagnet with a Curie temperature of 335 K in a narrow
+compositional range of 0.2 $\leq x\leq$ 0.25. This is the highest transition
+temperature among perovskite Co oxides. The saturation magnetization for $x=$
+0.225 is 0.25 $\mu_B$/Co at 10 K, which implies that the observed
+ferromagnetism is a bulk effect. We attribute this ferromagnetism to a peculiar
+Sr/Y ordering.",0411671v3
+2004-11-30,Helicoidal magnetic order in a clean copper oxide spin chain compound,"We report susceptibility, specific heat, and neutron diffraction measurements
+on NaCu$_2$O$_2$, a spin-1/2 chain compound isostructural to LiCu$_2$O$_2$,
+which has been extensively investigated. Below 13 K, we find a long-range
+ordered, incommensurate magnetic helix state with a propagation vector similar
+to that of LiCu$_2$O$_2$. In contrast to the Li analogue, substitutional
+disorder is negligible in NaCu$_2$O$_2$. We can thus rule out that the helix is
+induced by impurities, as was claimed on the basis of prior work on
+LiCu$_2$O$_2$. A spin Hamiltonian with frustrated longer-range exchange
+interactions provides a good description of both the ordered state and the
+paramagnetic susceptibility.",0411753v2
+2005-02-24,Spin-related magnetoresistance of n-type ZnO:Al and Zn_{1-x}Mn_{x}O:Al thin films,"Effects of spin-orbit coupling and s-d exchange interaction are probed by
+magnetoresistance measurements carried out down to 50 mK on ZnO and
+Zn_{1-x}Mn_{x}O with x = 3 and 7%. The films were obtained by laser ablation
+and doped with Al to electron concentration ~10^{20} cm^{-3}. A quantitative
+description of the data for ZnO:Al in terms of weak-localization theory makes
+it possible to determine the coupling constant \lambda_{so} = (4.4 +-
+0.4)*10^{-11} eVcm of the kp hamiltonian for the wurzite structure, H_{so} =
+\lambda_{so}*c(s x k). A complex and large magnetoresistance of
+Zn_{1-x}Mn_{x}O:Al is interpreted in terms of the influence of the s-d
+spin-splitting and magnetic polaron formation on the disorder-modified
+electron-electron interactions. It is suggested that the proposed model
+explains the origin of magnetoresistance observed recently in many magnetic
+oxide systems.",0502574v1
+2005-04-22,Possible Localization Behavior of the Inherent Conducting Polymer (CH$_3$)$_{0.9}$ReO$_3$,"Polymeric methyltrioxorhenium (poly-MTO) represents the first example of an
+inherent conducting organometallic oxide. It adopts the structural motives and
+transport properties of some classical perovskites in two dimensions. In this
+study we present resistivity data down to 30 mK which exhibit a crossover from
+a metallic (d$\rho$/d$T >$ 0) to an insulating (d$\rho$/d$T <$ 0) behavior at
+about 30 K. Below 30 K an unusual resistivity behavior, similar to that of some
+doped cuprate systems, is observed: initially the resistivity increases
+approximately as $\rho \sim$ log$(1/T$) before it starts to saturate below 2 K.
+Furthermore, a linear positive magnetoresistance is found (up to 7 T).
+Temperature dependent magnetization and specific heat measurements in various
+magnetic fields indicate that the unusual resistivity behavior may be driven by
+spatial localization of the d$^1$ moments at the Re atoms.",0504585v1
+2005-04-25,Influence of parasitic phases on the properties of BiFeO3 epitaxial thin films,"We have explored the influence of deposition pressure and temperature on the
+growth of BiFeO3 thin films by pulsed laser deposition onto (001)-oriented
+SrTiO3 substrates. Single-phase BiFeO3 films are obtained in a region close to
+10-2 mbar and 580C. In non-optimal conditions, X-ray diffraction reveals the
+presence of Fe oxides or of Bi2O3. We address the influence of these parasitic
+phases on the magnetic and electrical properties of the films and show that
+films with Fe2O3 systematically exhibit a ferromagnetic behaviour, while
+single-phase films have a low bulk-like magnetic moment. Conductive-tip atomic
+force microscopy mappings also indicate that Bi2O3 conductive outgrowths create
+shortcuts through the BiFeO3 films, thus preventing their practical use as
+ferroelectric elements in functional heterostructures.",0504631v1
+2005-05-01,"Exchange Biasing of the Ferromagnetic Semiconductor (Ga,Mn)As by MnO","We provide an overview of progress on the exchange biasing of a ferromagnetic
+semiconductor (Ga1-xMnxAs) by proximity to an antiferromagnetic oxide layer
+(MnO). We present a detailed characterization study of the antiferromagnetic
+layer using Rutherford backscattering spectrometry, x-ray photoelectron
+spectroscopy, transmission electron microscopy, and x-ray reflection. In
+addition, we describe the variation of the exchange and coercive fields with
+temperature and cooling field for multiple samples.",0505015v1
+2005-05-30,Magnetism and superconductivity of heavy fermion matter,"The interplay of magnetism and unconventional superconductivity (d singlet
+wave or p triplet wave) in strongly correlated electronic system (SCES) is
+discussed with recent examples found in heavy fermion compounds. A short
+presentation is given on the formation of the heavy quasiparticle with the two
+sources of a local and intersite enhancement for the effective mass. Two cases
+of the coexistence or repulsion of antiferromagnetism and superconductivity are
+given with CeIn3 and CeCoIn5. A spectacular example is the emergence of
+superconductivity in relatively strong itinerant ferromagnets UGe2 and URhGe.
+The impact of heavy fermion matter among other SCES as organic conductor or
+high Tc oxide is briefly pointed out.",0505713v2
+2005-06-23,"Interplay among Spin, Orbital and Lattice Degrees of Freedom in $t_{2g}$ Electron Systems with Edge-Sharing Network of Octahedra","Transition metal oxides whose lattice structure has edge-sharing network of
+octahedra constitute a diverse group of intriguing materials besides compounds
+with corner-sharing octahedra such as perovskites. We present a theoretical
+investigation of the interplay among spin, orbital and lattice degrees of
+freedom in these materials. We focus on $t_{2g}$ electron systems where a keen
+competition among those degrees of freedom is expected to emerge under a
+relatively weak Jahn-Teller coupling. We study the interplay between spin and
+orbital degrees of freedom in vanadium spinels and titanium pyroxenes. We
+clarify the important role of the strong anisotropy in the orbital interactions
+due to the edge-sharing geometry. We also discuss the interplay between spin
+and lattice in chromium spinels focusing on the magnetization process under the
+external magnetic field.",0506598v1
+2005-10-06,Ca_25Co_22O_56(OH)_28: a layered misfit compound,"The high pressure synthesis, structure and magnetic properties of
+Ca_25Co_22O_56(OH)_28 are reported. The compound has a misfit structure,
+consisting of double, square calcium oxide hydroxide rock-salt-like layers
+between hexagonal CoO_2 layers. The misfit compound crystallizes in the
+monoclinic space group C2/m, and can be characterized by the coexistence of two
+subsystems with common a=4.893(5)A, c=8.825(9)A and b=95.745(8) parameters, and
+different b parameters: b_RS=4.894(5)A, and b_HEX=2.809(3)A, for the rock-salt
+and hexagonal type planes respectively. The compound shows Curie-Weiss
+paramagnetism with an antiferromagnetic Weiss temperature of -43K and a reduced
+Co moment. Substantial deviations from Curie-Weiss behavior are seen below 50K
+with no indication of magnetic ordering. No superconductivity was observed down
+to a temperature of 2K.",0510137v2
+2005-11-18,Spin Correlations and Magnetic Susceptibilities of Lightly Doped Antiferromagnets,"We calculate the spin correlation function and the magnetic longitudinal and
+transverse susceptibilities of a two-dimensional antiferromagnet doped with a
+small concentration of holes, in the t-J model. We find that the motion of
+holes generates spin fluctuations which add to the quantum fluctuations, the
+spin correlations decaying with the inverse of the spin distance, while
+increasing with doping as the critical hole concentration, where the long-range
+order disappears, is approached. Moreover, the longitudinal susceptibility
+becomes finite in the presence of doping, due to the strong damping effects
+induced by the hole motion, while the transverse susceptibility is renormalized
+by softening effects. Both the longitudinal and the transverse susceptibilities
+increase with doping, the former more significantly than the latter. Our
+results imply that doping destroys the long-range order while local
+antiferromagnetic spin correlations persist. This is consistent with
+experiments on the doped copper oxide superconductors.",0511459v1
+2005-12-17,Stripe phases - possible ground state of the high-Tc superconductors,"Based on the mean-field method applied either to the extended single-band
+Hubbard model or to the single-band Peierls-Hubbard Hamiltonian we study the
+stability of both site-centered and bond-centered charge domain walls. The
+difference in energy between these phases is found to be small. Therefore,
+moderate perturbations to the pure Hubbard model, such as next nearest hopping,
+lattice anisotropy, or coupling to the lattice, induce phase transitions, shown
+in the corresponding phase diagrams. In addition, we determine for stable
+phases charge and magnetization densities, double occupancy, kinetic and
+magnetic energies, and investigate the role of a finite electron-lattice
+coupling. We also review experimental signatures of stripes in the
+superconducting copper oxides.",0512420v1
+2006-02-07,Field-Induced Ferromagnetic Order and Colossal Magnetoresistance in La_{1.2}Sr_{1.8}Mn_2O_7: a ^{139}La NMR study,"In order to gain insights into the origin of colossal magneto-resistance
+(CMR) in manganese oxides, we performed a ^{139}La NMR study in the
+double-layered compound La_{1.2}Sr_{1.8}Mn_2O_7. We find that above the Curie
+temperature T_C=126 K, applying a magnetic field induces a long-range
+ferromagnetic order that persists up to T=330 K. The critical field at which
+the induced magnetic moment is saturated coincides with the field at which the
+CMR effect reaches to a maximum. Our results therefore indicate that the CMR
+observed above T_C in this compound is due to the field-induced ferromagnetism
+that produces a metallic state via the double exchange interaction.",0602161v1
+2006-03-01,Model for vacancy-induced d$^0$ ferromagnetism in oxide compounds,"We propose a model with few parameters, for vacancy-induced ferromagnetism
+based on a correlated model for anions (oxygen orbitals) with random potentials
+that represent cation vacancies. There is a range of potential strength for
+which moments appear on oxygen sites neighboring the vacancies. By using
+techniques which allow us to treat the randomness exactly, we calculate the
+magnetic couplings between the total moment around each vacancy, the Curie
+temperature and dynamical correlations as a function of the effective stren gth
+of the vacancy potential and doping properties, the density of vacancies, as
+well as the correlation and band width of the host. For physically reasonable
+parameters this predicts Curie temperatures well above room temperature for
+small concentrations of vacancies and appropriate parameters. We disc uss our
+results in relation to questions of stability and reproducibility raised in
+experiments. To circumvent the difficulties of controlling intrinsic defects,
+we propose specific non-magnetic host doping that could be, for example,
+substituted for cations in HfO$_2$ or ZrO$_2$.",0603022v2
+2006-04-13,Angle-dependence of the Hall effect in HgBa2CaCu2O6 thin films,"Superconducting compounds of the family Hg-Ba-Ca-Cu-O have been the subject
+of intense study since the current record-holder for the highest critical
+temperature of a superconductor belongs to this class of materials. Thin films
+of the compound with two adjacent copper-oxide layers and a critical
+temperature of about 120 K were prepared by a two-step process that consists of
+the pulsed-laser deposition of precursor films and the subsequent annealing in
+mercury-vapor atmosphere. Like some other high-temperature superconductors,
+Hg-Ba-Ca-Cu-O exhibits a specific anomaly of the Hall effect, a double-sign
+change of the Hall coefficient close to the superconducting transition. We have
+investigated this phenomenon by measurements of the Hall effect at different
+angles between the magnetic field direction and the crystallographic c-axis.
+The results concerning the upper part of the transition, where the first sign
+change occurs, are discussed in terms of the renormalized fluctuation model for
+the Hall conductivity, adapted through the field rescaling procedure in order
+to take into account the arbitrary orientation of the magnetic field.",0604352v1
+2006-05-11,Multifilament YBa2Cu3O6+x -coated conductors with minimized coupling losses,"We report an experimental approach to making multifilament coated conductors
+with low losses in applied time-varying magnetic field. Previously, the
+multifilament conductors obtained for that purpose by laser ablation suffered
+from high coupling losses. Here we report how this problem can be solved. When
+the substrate metal in the grooves segregating the filaments is exposed to
+oxygen, it forms high resistivity oxides that electrically insulate the stripes
+from each other and from the substrate. As the result, the coupling loss has
+become negligible over the entire range of tested parameters (magnetic field
+amplitudes B and frequencies f) available to us.",0605313v1
+2006-11-09,New ultrasmall iron-oxide nanoparticles with high magnetisation as potential T1-MRI contrast agents for Molecular Imaging,"Here we report on the synthesis of very small gamma-Fe2O3 nanoparticles (5
+nm) presenting very narrow particle size distribution and exceptionally high
+saturation magnetisation. The synthesis has been carried out in an organic
+medium with subsequent transfer to an aqueous solution at physiological pH. The
+structural and magnetic properties were kept unaltered after the solvent
+exchange. NMR relaxometric measurements show the potential of these particles
+as specific reporters for magnetic resonance molecular imaging.",0611243v1
+2006-11-20,Spin correlation in kagomé ice state: neutron scattering study of the dipolar spin ice Dy_{2}Ti_{2}O_{7} under magnetic field along [111],"We have investigated the kagom\'{e} ice state in the frustrated pyrochlore
+oxide Dy_{2}Ti_{2}O_{7} under magnetic field along a [111] axis. Spin
+correlations have been measured by neutron scattering and analyzed by
+Monte-Carlo simulation. The kagom\'{e} ice state, which has a non-vanishing
+residual entropy well established for the nearest-neighbor spin ice model by
+the exact solution, has been proved to be realized in the dipolar-interacting
+spin ice Dy_{2}Ti_{2}O_{7} by observing the characteristic spin correlations.
+The simulation shows that the long-range interaction gives rise to only weak
+lifting of the ground state degeneracy and that the system freezes within the
+degenerate kagom\'{e} ice manifold .",0611527v2
+2007-04-23,Two-Staged Magnetoresistance Driven by Ising-like Spin Sublattice in SrCo6O11,"A two-staged, uniaxial magnetoresistive effect has been discovered in
+SrCo6O11 having a layered hexagonal structure. Conduction electrons and
+localized Ising spins are in different sublattices but their interpenetration
+makes the conduction electrons sensitively pick up the stepwise
+field-dependence of magnetization. The stepwise field-dependence suggests two
+competitive interlayer interactions between ferromagnetic Ising-spin layers,
+i.e., a ferromagnetic nearest-layer interaction and an antiferromagnetic
+next-nearest-layer interaction. This oxide offers a unique opportunity to study
+nontrivial interplay between conduction electrons and Ising spins, the coupling
+of which can be finely controlled by a magnetic field of a few Tesla.",0704.3025v2
+2007-05-17,Incoherent non-Fermi liquid scattering in a Kondo lattice,"One of the most notorious non-Fermi liquid properties of both archetypal
+heavy-fermion systems [1-4] and the high-Tc copper oxide superconductors [5] is
+an electrical resistivity that evolves linearly with temperature, T. In the
+heavy-fermion superconductor CeCoIn5 [5], this linear behaviour was one of the
+first indications of the presence of a zero-temperature instability, or quantum
+critical point. Here, we report the observation of a unique control parameter
+of T-linear scattering in CeCoIn5, found through systematic chemical
+substitutions of both magnetic and non-magnetic rare-earth, R, ions into the Ce
+sub-lattice. We find that the evolution of inelastic scattering in Ce1-xRxCoIn5
+is strongly dependent on the f-electron configuration of the R ion, whereas two
+other key properties -- Cooper-pair breaking and Kondo-lattice coherence -- are
+not. Thus, T-linear resistivity in CeCoIn5 is intimately related to the nature
+of incoherent scattering centers in the Kondo lattice, which provides insight
+into the anomalous scattering rate synonymous with quantum criticality [7].",0705.2592v2
+2007-06-05,Structure-Property Relationship in the Ordered-Perovskite- Related Oxide Sr3.12Er0.88Co4O10.5,"Synchrotron X-ray diffraction patterns were measured and analyzed for a
+polycrystalline sample of the room-temperature ferromagnet Sr3.12Er0.88Co4O10.5
+from 300 to 650 K, from which two structural phase transitions were found to
+occur successively. The higher-temperature transition at 509 K is driven by
+ordering of the oxygen vacancies, which is closely related to the metallic
+state at high temperatures. The lower-temperature transition at 360 K is of
+first order, at which the ferromagnetic state suddenly appears with exhibiting
+a jump in magnetization and resistivity. Based on the refined structure,
+possible spin and orbital models for the magnetic order are proposed.",0706.0605v2
+2007-06-28,Non-Fermi-liquid behavior in nearly ferromagnetic metallic SrIrO3 single crystals,"We report transport and thermodynamic properties of single-crystal SrIrO3 as
+a function of temperature T and applied magnetic field H. We find that SrIrO3
+is a non-Fermi-liquid metal near a ferromagnetic instability, as characterized
+by the following properties: (1) small ordered moment but no evidence for
+long-range order down to 1.7 K; (2) strongly enhanced magnetic susceptibility
+that diverges as T or T1/2 at low temperatures, depending on the applied field;
+(3) heat capacity C(T,H) ~ -Tlog T that is readily amplified by low applied
+fields; (4) a strikingly large Wilson ratio at T< 4K; and (5) a T3/2-dependence
+of electrical resistivity over the range 1.7 < T < 120 K. A phase diagram based
+on the data implies SrIrO3 is a rare example of a stoichiometric oxide compound
+that exhibits non-Fermi-liquid behavior near a quantum critical point (T = 0
+and H = 0.23 T).",0706.4319v1
+2007-07-20,The Ba2LnFeNb4O15 Tetragonal Tungsten Bronze: towards RT composite multiferroics,"Several Niobium oxides of formula Ba2LnFeNb4O15 (Ln = La, Pr, Nd, Sm, Eu, Gd)
+with the Tetragonal Tungsten Bronze (TTB) structure have been synthesised by
+conventional solid-state methods. The Neodymium, Samarium and Europium
+compounds are ferroelectric with Curie temperature ranging from 320 to 440K.
+The Praseodymium and Gadolinium compounds behave as relaxors below 170 and 300
+K respectively. The Praseodymium, Neodymium, Samarium, Europium and Gadolinium
+compounds exhibit magnetic hysteresis loops at room temperature originating
+from traces of a barium ferrite secondary phase. The presence of both
+ferroelectric and magnetic hysteresis loops at room temperature allows
+considering these materials as composites multiferroic. Based on
+crystal-chemical analysis we propose some relationships between the
+introduction of Ln3+ ions in the TTB framework and the chemical, structural and
+physical properties of these materials.",0707.3112v2
+2007-07-24,Role of magnetism and electron-lattice interactions in STM spectra of cuprates,"The study of bosonic modes that couple to the charge carriers is a key
+element in understanding superconductivity. Lee et al. have used
+atomic-resolution scanning tunneling spectroscopy (STM) in an attempt to
+extract the spectrum of of these modes in the high temperature superconductor
+Bi2Sr2CaCu2O8+d and they found a mode whose frequency did not depend on doping
+but changed on 16O to 18O isotopic substitution leading them to suggest a role
+for lattice modes (phonons). A careful examination of their published data
+reveals a weaker but distinct feature that has all the characteristics of the
+magnetic excitation identified as the bosonic mode in other competing
+experiments. We suggest the lattice mode seen by Lee et al. is not relevant to
+superconductivity and is due to inelastic tunneling through the insulating
+oxide layer.",0707.3623v1
+2007-10-16,Formation of collective spins in frustrated clusters,"Using magnetization, specific heat and neutron scattering measurements, as
+well as exact calculations on realistic models, the magnetic properties of the
+\lacuvo compound are characterized on a wide temperature range. At high
+temperature, this oxide is well described by strongly correlated atomic $S$=1/2
+spins while decreasing the temperature it switches to a set of weakly
+interacting and randomly distributed entangled pseudo spins $\tilde S=1/2$ and
+$\tilde S=0$. These pseudo-spins are built over frustrated clusters, similar to
+the kagom\'e building block, at the vertices of a triangular superlattice, the
+geometrical frustration intervening then at different scales.",0710.3025v2
+2007-11-01,Magnetic resonance in iron oxide nanoparticles: quantum features and effect of size,"In order to better understand the transition from quantum to classical
+behavior in spin system, electron magnetic resonance (EMR) is studied in
+suspensions of superparamagnetic magnetite nanoparticles with an average
+diameter of ~ 9 nm and analyzed in comparison with the results obtained in the
+maghemite particles of smaller size (~ 5 nm). It is shown that both types of
+particles demonstrate common EMR behavior, including special features such as
+the temperature-dependent narrow spectral component and multiple-quantum
+transitions. These features are common for small quantum systems and not
+expected in classical case. The relative intensity of these signals rapidly
+decreases with cooling or increase of particle size, marking gradual transition
+to the classical FMR behavior.",0711.0168v1
+2007-12-14,Magnetic properties of HO2 thin films,"We report on the magnetic and transport studies of hafnium oxide thin films
+grown by pulsed-laser deposition on sapphire substrates under different oxygen
+pressures, ranging from 10-7 to 10-1 mbar. Some physical properties of these
+thin films appear to depend on the oxygen pressure during growth: the film
+grown at low oxygen pressure (P ~= 10-7 mbar) has a metallic aspect and is
+conducting, with a positive Hall signal, while those grown under higher oxygen
+pressures (7 x 10-5 <= P <= 0.4 mbar) are insulating. However, no intrinsic
+ferromagnetic signal could be attributed to the HfO2 films, irrespective of the
+oxygen pressure during the deposition.",0712.2410v1
+2008-05-30,Doped orbitally-ordered systems: another case of phase separation,"A possible mechanism of electronic phase separation in the systems with
+orbital ordering is analyzed. We suggest a simple model taking into account an
+interplay between the delocalization of charge carriers introduced by doping
+and the cooperative ordering of local lattice distortions. The proposed
+mechanism is quite similar to the double exchange usually invoked for
+interpretation of phase separation in doped magnetic oxides like manganites,
+but can be efficient even in the absence of any magnetic ordering. It is
+demonstrated that the delocalized charge carriers favor the formation of
+nanoscale inhomogeneities with the orbital structure different from that in the
+undoped material. The directional character of orbitals leads to
+inhomogeneities of different shapes and sizes.",0805.4806v1
+2008-06-16,Structural and magnetic phase diagram of CeFeAsO1-xFx and its relationship to high-temperature superconductivity,"We use neutron scattering to study the structural and magnetic phase
+transitions in the iron pnictides CeFeAsO1-xFx as the system is tuned from a
+semimetal to a high-transition-temperature (high-Tc) superconductor through
+Fluorine (F) doping x. In the undoped state, CeFeAsO develops a structural
+lattice distortion followed by a stripe like commensurate antiferromagnetic
+order with decreasing temperature. With increasing Fluorine doping, the
+structural phase transition decreases gradually while the antiferromagnetic
+order is suppressed before the appearance of superconductivity, resulting an
+electronic phase diagram remarkably similar to that of the high-Tc copper
+oxides. Comparison of the structural evolution of CeFeAsO1-xFx with other
+Fe-based superconductors reveals that the effective electronic band width
+decreases systematically for materials with higher Tc. The results suggest that
+electron correlation effects are important for the mechanism of high-Tc
+superconductivity in these Fe pnictides.",0806.2528v1
+2008-06-20,Destruction of Neel order and appearance of superconductivity in electron-doped cuprates by oxygen annealing process,"We use thermodynamic and neutron scattering measurements to study the effect
+of oxygen annealing on the superconductivity and magnetism in
+Pr$_{0.88}$LaCe$_{0.12}$CuO$_{4-\delta}$. Although the transition temperature
+$T_c$ measured by susceptibility and superconducting coherence length increase
+smoothly with gradual oxygen removal from the annealing process, bulk
+superconductivity, marked by a specific heat anomaly at $T_c$ and the presence
+of a neutron magnetic resonance, only appears abruptly when $T_c$ is close to
+the largest value. These results suggest that the effect of oxygen annealing
+must be first determined in order to establish a Ce-doping dependence of
+antiferromagnetism and superconductivity phase diagram for electron-doped
+copper oxides.",0806.3426v1
+2008-06-26,A Multiferroic Ceramic with Perovskite Structure: La0.5Bi0.5Mn0.5Fe0.5O3.09,"ABO3 perovskite multiferroic La0.5Bi0.5Mn0.5Fe0.5O3.09 where the B-site
+cations is responsible for the magnetic properties and the A-site cation with
+lone pair electron is responsible for the ferroelectric properties was
+synthesized at normal conditions. This oxide exhibits a ferromagnetic
+transition around 240 K with a well defined hysteresis loop, and a significant
+reversible remnant polarization below 67K similar to ferroelectric behavior.
+The magnetic interaction is interpreted by the ferromagnetic Fe3+-O-Mn3+ and
+antiferromagnetic Fe3+(Mn3+)-O-Fe3+(Mn3+) interactions competed each other,
+whereas the ferroelectricity is predominantly due to the polar nature
+introduced by the 6s2 lone pair of Bi3+ cations",0806.4274v1
+2008-10-07,Interface Ferromagnetism in (110)-Oriented La0.7Sr0.3MnO3/SrTiO3 Ultrathin Superlattices,"We explore manganite interface magnetism in epitaxially grown
+La0.7Sr0.3MnO3(LSMO)/SrTiO3 ultrathin superlattices (SL) along (110)
+orientation. we show that robust ferromagnetism persists down to four
+monolayers LSMO(MLs) (~1.1 nm in thickness), of which 50% Mn is at the
+interface state. Above eight MLs, the magnetic moment is nearly saturated to
+the theoretical value of 3.7u_B, with an estimated interface moment of 3.2u_B.
+In comparison to (100)-oriented SLs which were previously shown to have a spin
+canted ground state, (110)-oriented SLs exhibit stronger low-dimensional
+ferromagnetism and better metallicity, suggesting a ferromagnetic interface
+spin state well suited for all-oxide spintronic devices. The underlining
+mechanism is qualitatively discussed.",0810.1309v2
+2008-10-31,Quantum electric dipole glass and frustrated magnetism near a critical point in Li2ZrCuO4,"We report a new peculiar effect of the interaction between a sublattice of
+frustrated quantum spin-1/2 chains and a sublattice of pseudospin-1/2 centers
+(quantum electric dipoles) uniquely co-existing in the complex oxide Li2ZrCuO4.
+7Li nuclear magnetic-, Cu2+ electron spin resonance and a complex dielectric
+constant data reveal that the sublattice of Li+-derived electric dipoles orders
+glass like at Tg ~ 70 K yielding a spin site nonequivalency in the CuO2 chains.
+We suggest that such a remarkable interplay between electrical and spin degrees
+of freedom might strongly influence the properties of the spiral spin state in
+Li2ZrCuO4 that is close to a quantum ferromagnetic critical point. In
+particular that strong quantum fluctuations and/or the glassy behavior of
+electric dipoles might renormalize the exchange integrals affecting this way
+the pitch angle of the spiral as well as be responsible for the missing
+multiferroicity present in other helicoidal magnets.",0810.5754v3
+2009-01-20,Nonvolatile SRAM architecture using MOSFET-based spin-transistors,"The authors proposed and computationally analyzed nonvolatile static random
+access memory (NV-SRAM) architecture using metal-oxide-semiconductor
+field-effect transistor (MOSFET) type of spin-transistors referred to as
+pseudo-spin-MOSFET (PS-MOSFET). PS-MOSFET is a new circuit approach to
+reproduce the functions of spin-transistors, based on recently progressed
+magnetoresistive random access memory (MRAM) technology. The proposed NV-SRAM
+cell can be simply configured by connecting two PS-MOSFETs to the storage nodes
+of a standard SRAM cell. The logic information of the storage nodes can be
+electrically stored into the magnetic tunnel junctions (MTJs) of the PS-MOSFETs
+by current-induced magnetization switching (CIMS), and the stored information
+is automatically restored when the inverter loop circuit wakes up. In addition,
+the proposed NV-SRAM cell has no influence on the performance of normal SRAM
+operations. Low power dissipation and high degree of freedom of MTJ design are
+also remarkable features for NV-SRAM using PS-MOSFETs.",0901.2980v1
+2009-02-28,Magneto-optical readout of dark exciton distribution in cuprous oxide,"An experimental study of the yellow exciton series in Cu2O in strong magnetic
+fields up to 32 T shows the optical activation of direct and phonon-assisted
+paraexciton luminescence due to mixing with the quadruple allowed orthoexciton
+state. The observed phonon-assisted luminescence yields information on the
+statistical distribution of occupied states. Additional time-resolved
+experiments provide a unique opportunity to directly determine the time
+evolution of the thermodynamical properties of the paraexciton gas. Because the
+lifetime of paraexciton is hardly affected by the optical activation in a
+strong magnetic field, this opens new possibilities for studies aiming at
+Bose-Einstein condensation of excitons in bulk semiconductors.",0903.0072v1
+2009-03-31,Gigantic Impact of Magnetic Impurity on Stripe Order in La$_{2-x}$Sr$_{x}$CuO$_4$ ($x$$\sim$1/8),"Precise neutron-scattering experiments on
+La$_{1.88-y}$Sr$_{0.12+y}$Cu$_{0.99}$R$_{0.01}$O$_4$ ($y$=0 for R=Cu, Zn and
+$y$=0.01 for R=Ga, Fe) were performed to examine the stability of stripe order
+in cuprate oxides through impurity substitution effects. For all the
+impurity-substituted samples a static charge-density-wave order similar to that
+reported in the low-temperature-tetragonal phase (LTT) was discovered in the
+low-temperature-orthorhombic (LTO) phase for the first time. Fe substitution
+significantly enhanced both the charge- and spin-density-wave orders. These
+results indicate that dynamical charge stripes can be stabilized into static
+ones around the Cu-site defects regardless of the type of crystal structure.
+Additionally, large magnetic moments at the Cu-site may induce a decrease in
+the Cu spin fluctuations around the defects, which in turn, enhances the static
+charge-density-wave order.",0903.5391v1
+2009-04-27,Role of Oxygen Electrons in the Metal-Insulator Transition in the Magnetoresistive Oxide La$_{2-2x}$Sr$_{1+2x}$Mn$_2$O$_7$ Probed by Compton Scattering,"We have studied the [100]-[110] anisotropy of the Compton profile in the
+bilayer manganite. Quantitative agreement is found between theory and
+experiment with respect to the anisotropy in the two metallic phases (i.e. the
+low temperature ferromagnetic and the colossal magnetoresistant phase under a
+magnetic field of 7 T). Robust signatures of the metal-insulator transition are
+identified in the momentum density for the paramagnetic phase above the Curie
+temperature. We interpret our results as providing direct evidence for the
+transition from the metallic-like to the admixed ionic-covalent bonding
+accompanying the magnetic transition. The number of electrons involved in this
+phase transition is estimated from the area enclosed by the Compton profile
+anisotropy differences. Our study demonstrates the sensitivity of the Compton
+scattering technique for identifying the number and type of electrons involved
+in the metal-insulator transition.",0904.4255v1
+2009-05-04,Ferromagnetism in Carbon doped Zinc Oxide Systems,"We report spin polarized density functional calculations of ferromagnetic
+properties of a series of ZnO clusters and solid containing one or two
+substitutional carbon impurities. We analyze the eigen value spectra, spin
+densities and molecular orbitals, and induced magnetic moments for ZnC,
+Zn$_{2}$C, Zn$_{2}$OC, carbon substituted clusters Zn$_{n}$O$_{n}$ (n=3--10,
+12) and ZnO solid. The results show that the doping induces magnetic moment of
+the $\sim$2 $\mu_{B}$ in all the cases. All the systems with two carbon
+impurities show ferromagnetic interaction except when the carbon atoms share
+the same Zn atom as the nearest neighbor. This ferromagnetic interaction is
+predominantly mediated via $\pi$ bonds in ring structures and through $\pi$ and
+$\sigma$ bonds in three dimensional structure. The calculations also show that
+the interaction is significantly enhanced in solid, bringing out the role of
+dimensionality of Zn-O network connecting two carbon atoms.",0905.0366v1
+2009-05-11,Flux dynamics in NdO1-xFxFeAs bulk sample,"We present data of multi harmonic magneto-dynamic experiments. In particular,
+we performed ac magnetic susceptibility experiments on layered pnictide-oxide
+quaternary compound NdOFeAs doped with fluorine. The experiments allow measure
+the critical temperature and probe the flux dynamic behavior using the third
+harmonic component of the ac susceptibility of a NdF0.16FeAsO0.84 bulk sample
+as a function of temperature and frequency of the applied ac magnetic fields.
+Measured signals are connected with the non-linear superconducting flux dynamic
+behavior and are characterized by a flux critical states sustaining a
+superconducting critical current. In this framework the irreversibility line
+that describes the stable superconducting state has been extracted from the
+onset of the third harmonic signal vs. frequency. Finally we present also the
+analysis of the flux dynamic dimensionality in the investigated sample.",0905.1633v1
+2009-06-11,Spin polarized electron transport near the Si/SiO2 interface,"Using long-distance lateral devices, spin transport near the interface of Si
+and its native oxide (SiO2) is studied by spin-valve measurements in an
+in-plane magnetic field and spin precession measurements in a perpendicular
+magnetic field at 60K. As electrons are attracted to the interface by an
+electrostatic gate, we observe shorter average spin transit times and an
+increase in spin coherence, despite a reduction in total spin polarization.
+This behavior, which is in contrast to the expected exponential depolarization
+seen in bulk transport devices, is explained using a transform method to
+recover the empirical spin transit-time distribution and a simple two-stage
+drift-diffusion model. We identify strong interface-induced spin depolarization
+(reducing the spin lifetime by over two orders of magnitude from its bulk
+transport value) as the consistent cause of these phenomena.",0906.2146v2
+2009-07-09,Spin-lattice coupling in frustrated antiferromagnets,"We review the mechanism of spin-lattice coupling in relieving the geometrical
+frustration of pyrochlore antiferromagnets, in particular spinel oxides. The
+tetrahedral unit, which is the building block of the pyrochlore lattice,
+undergoes a spin-driven Jahn-Teller instability when lattice degrees of freedom
+are coupled to the antiferromagnetism. By restricting our considerations to
+distortions which preserve the translational symmetries of the lattice, we
+present a general theory of the collective spin-Jahn-Teller effect in the
+pyrochlore lattice. One of the predicted lattice distortions breaks the
+inversion symmetry and gives rise to a chiral pyrochlore lattice, in which
+frustrated bonds form helices with a definite handedness. The chirality is
+transferred to the spin system through spin-orbit coupling, resulting in a
+long-period spiral state, as observed in spinel CdCr2O4. We discuss explicit
+models of spin-lattice coupling using local phonon modes, and their
+applications in other frustrated magnets.",0907.1693v1
+2009-09-08,Magnetism and orbital-ordering in an interacting three band model: a dynamical mean field study,"Single-site dynamical mean field theory is used to determine the magnetic and
+orbital-ordering phase diagram for a model of electrons moving on a lattice
+with three orbital states per site and with the fully rotationally invariant
+Slater-Kanamori on-site interactions. The model captures important aspects of
+the physics of transition metal oxides with partially filled $t_{2g}$ shells,
+and of electron-doped C$_{60}$. We introduce an unbiased, computationally
+simple and inexpensive method for estimating the presence of two sublattice
+order, determine the regimes in which spatially uniform and two-sublattice spin
+and orbital orderings are present and give physical arguments for the origins
+of the different phases. Guidelines are determined for optimizing the presence
+of ferromagnetism, which may be desirable in applications",0909.1499v1
+2010-07-19,Electronic Structure of Weakly Correlated Antiferromagnetic Metal SrCrO3: First-principles calculations,"By systematic first-principles calculations, we study the electronic
+structure and magnetic property of SrCrO$_3$. Our results suggest that
+SrCrO$_3$ is a weakly correlated antiferromagnetic (AF) metal, a very rare
+situation in transition-metal oxides. Among various possible AF states, the
+C-type spin ordering with small amount of orbital polarization (dxy orbital is
+more occupied than the d_{yz/zx} orbital) is favored. The detailed mechanism to
+stabilize the C-type AF state is analyzed based on the competition between the
+itinerant Stoner instability and superexchange, and our results suggest that
+the magnetic instability rather than the orbital or lattice instabilities plays
+an important role in this system. The experimentally observed compressive
+tetragonal distortion can be naturally explained from the C-type AF state. By
+applying the LDA+$U$ method to study this system, we show that wrong ground
+state will be obtained if $U$ is large.",1007.3156v1
+2010-08-16,Topological Magnetic Insulators with Corundum Structure,"Topological insulators are new states of quantum matter in which surface
+states residing in the bulk insulating gap are protected by time-reversal
+symmetry. When a proper kind of antiferromagnetic long range order is
+established in a topological insulator, the system supports axionic
+excitations. In this paper, we study theoretically the electronic states in a
+transition metal oxide of corundum structure, in which both spin-orbit
+interaction and electron-electron interaction play crucial roles. A
+tight-binding model analysis predicts that materials with this structure can be
+strong topological insulator. Because of the electron correlation, an
+antiferromagnetic order may develop, giving rise to a topological magnetic
+insulator phase with axionic excitations.",1008.2666v1
+2010-08-19,Electronic and magnetic properties of SrTiO3/LaAlO3 interfaces from first principles,"A number of intriguing properties emerge upon the formation of the epitaxial
+interface between the insulating oxides LaAlO3 and SrTiO3. These properties,
+which include a quasi two-dimensional conducting electron gas, low temperature
+superconductivity, and magnetism, are not present in the bulk materials,
+generating a great deal of interest in the fundamental physics of their
+origins. While it is generally accepted that the novel behavior arises as a
+result of a combination of electronic and atomic reconstructions and
+growth-induced defects, the complex interplay between these effects remains
+unclear. In this report, we review the progress that has been made towards
+unraveling the complete picture of the SrTiO3/LaAlO3 interface, focusing
+primarily on present ab initio theoretical work and its relation to the
+experimental data. In the process, we highlight some key unresolved issues and
+discuss how they might be addressed by future experimental and theoretical
+studies.",1008.3379v1
+2010-10-26,Suppression of the Néel temperature in hydrothermally synthesized alpha-Fe2O3 nanoparticles,"Magnetic measurements up to 1000 K have been performed on hydrothermally
+synthesized $\alpha$-Fe$_{2}$O$_{3}$ nanoparticles (60 nm) using a Quantum
+Design vibrating sample magnetometer. A high vacuum environment
+(1$\times$10$^{-5}$ torr) during the magnetic measurement up to 1000 K leads to
+a complete reduction of $\alpha$-Fe$_{2}$O$_{3}$ to Fe$_{3}$O$_{4}$. This
+precludes the determination of the N\'eel temperature for the
+$\alpha$-Fe$_{2}$O$_{3}$ nanoparticles. In contrast, coating
+$\alpha$-Fe$_{2}$O$_{3}$ nanoparticles with SiO$_{2}$ stabilizes the
+$\alpha$-Fe$_{2}$O$_{3}$ phase up to 930 K, which allows us to determine the
+N\'eel temperature of the $\alpha$-Fe$_{2}$O$_{3}$ nanoparticles for the first
+time. The N\'eel temperature of the 60-nm $\alpha$-Fe$_{2}$O$_{3}$
+nanoparticles is found to be 945 K, about 15 K below the bulk value. The small
+reduction of the N\'eel temperature of the $\alpha$-Fe$_{2}$O$_{3}$
+nanoparticles is consistent with a finite-size scaling theory. Our current
+results also show that coating nanoparticles with SiO$_{2}$ can effectively
+protect nanoparticles from oxidation or reduction, which is important to
+technological applications.",1010.5294v1
+2010-12-10,The Curie temperature and exchange energy between two sublattices in half-metallic greigite Fe3S4,"High-temperature magnetic measurements have been carried out in
+hydrothermally synthesized greigite (Fe3S4). We show that the Curie temperature
+of greigite is significantly lower than that for its iron oxide counterpart
+Fe3O4. The lower TC value (about 677 K) of greigite is in quantitative
+agreement with that calculated using the exchange energy (3.25 meV) and the
+spin values of the two sublattices, which are inferred from the neutron and
+magnetization data of high-quality pure greigite samples. We further show that,
+with an effective on-site Hubbard energy Ueff = 1.16 eV, the lattice constant
+and two sublattice spins predicted from ab initio density-function theory are
+in nearly perfect agreement with the measured values. The parameter Ueff = 1.16
+eV ensures Fe3S4 to be an excellent half-metallic material for spintronic
+applications.",1012.2364v1
+2010-12-13,Magnetocaloric effect and improved relative cooling power in (La0.7Sr0.3MnO3/SrRuO3) superlattices,"Magnetic properties of a series of (La0.7Sr0.3MnO3/SrRuO3) superlattices,
+where the SrRuO3 layer thickness is varying, are examined. A room-temperature
+magnetocaloric effect is obtained owing to the finite size effect which reduces
+the TC of La0.7Sr0.3MnO3 layers. While the working temperature ranges are
+enlarged,, -DeltaSmax values remains similar to the values in polycrystalline
+La0.7Sr0.3MnO3. Consequently, the relative cooling powers are significantly
+improved, the microscopic mechanism of which is related to the effect of the
+interfaces at La0.7Sr0.3MnO3/SrRuO3 and higher nanostructural disorder. This
+study indicates that artificial oxide superlattices/multilayers might provide
+an alternative pathway in searching for efficient room-temperature magnetic
+refrigerators for (nano)microscale systems.",1012.2675v1
+2011-01-14,Magnetic Frustration in a Mn Honeycomb Lattice Induced by Mn-O-O-Mn Pathways,"We investigated the electronic structure of layered Mn oxide Bi3Mn4O12(NO3)
+with a Mn honeycomb lattice by x-ray absorption spectroscopy. The valence of Mn
+was determined to be 4+ with a small charge-transfer energy. We estimated the
+values of superexchange interactions up to the fourth nearest neighbors (J1,
+J2, J3, and J4) by unrestricted Hartree-Fock calculations and a perturbation
+method. We found that the absolute values of J1 through J4 are similar with
+positive (antiferromagnetic) J1 and J4, and negative (ferromagnetic) J2 and J3,
+due to Mn-O-O-Mn pathways activated by the smallness of charge-transfer energy.
+The negative J3 provides magnetic frustration in the honeycomb lattice to
+prevent long-range ordering.",1101.2847v1
+2011-01-28,Sr3Co2O6: a possible frustrated spin-chain material,"A dense phase of a post-layered perovskite Sr3Co2O6 was created by a
+high-pressure and high-temperature synthetic route and quenched to ambient
+conditions. The structure of Sr3Co2O6 was determined by synchrotron X-ray
+powder diffraction. Sr3Co2O6 crystallizes in the K4CdCl6-type structure (an
+infinite chain-type structure), which is 6% denser than the known,
+iso-compositional layered perovskite Sr3Co2O7-d (d~1). The K4CdCl6-type
+Sr3Co2O6 shows complex magnetic behavior reflecting the spin-chain nature as
+well as the analogue oxides Ca3Co2O6 and Ca3CoRhO6, whose microscopic magnetic
+origin is still highly debated.",1101.5457v1
+2011-04-15,Structural and Magnetic Phase Transitions in NdCoAsO under High Pressures,"We have investigated structural and magnetic phase transitions under high
+pressures in a quaternary rare earth transition metal arsenide oxide NdCoAsO
+compound that is isostructural to high temperature superconductor NdFeAsO.
+Four-probe electrical resistance measurements carried out in a designer diamond
+anvil cell show that the ferromagnetic Curie temperature and anti-ferromagnetic
+Neel temperature increase with an increase in pressure. High pressure x-ray
+diffraction studies using a synchrotron source show a structural phase
+transition from a tetragonal phase to a new crystallographic phase at a
+pressure of 23 GPa at 300 K. The NdCoAsO sample remained anti-ferromagnetic and
+non-superconducting to temperatures down to 10 K and to the highest pressure
+achieved in this experiment of 53 GPa. A P-T phase diagram for NdCoAsO is
+presented to a pressure of 53 GPa and low temperatures of 10 K.",1104.3172v1
+2011-05-03,Exchange interactions and magnetic phases of transition metal oxides: benchmarking advanced ab initio methods,"The magnetic properties of the transition metal monoxides MnO and NiO are
+investigated at equilibrium and under pressure via several advanced
+first-principles methods coupled with Heisenberg Hamiltonian MonteCarlo. The
+comparative first-principles analysis involves two promising beyond-local
+density functionals approaches, namely the hybrid density functional theory and
+the recently developed variational pseudo-self-interaction correction method,
+implemented with both plane-wave and atomic-orbital basis sets. The advanced
+functionals deliver a very satisfying rendition, curing the main drawbacks of
+the local functionals and improving over many other previous theoretical
+predictions. Furthermore, and most importantly, they convincingly demonstrate a
+degree of internal consistency, despite differences emerging due to
+methodological details (e.g. plane waves vs. atomic orbitals)",1105.0647v3
+2011-05-16,Isotope effects in high-Tc cuprate superconductors: Ultimate proof for bipolaron theory of superconductivity,"Developing a theory of high-temperature superconductivity in copper oxides is
+one of the outstanding problems in physics. Twenty-five years after its
+discovery, no consensus on the microscopic theory has been reached despite
+tremendous theoretical and experimental efforts. Attempts to understand this
+problem are hindered by the subtle interplay among a few mechanisms and the
+presence of several nearly degenerate and competing phases in these systems.
+Here we provide unified parameter-free explanation of the observed
+oxygen-isotope effects on the critical temperature, the magnetic-field
+penetration depth, and on the normal-state pseudogap for underdoped cuprate
+superconductors within the framework of the bipolaron theory compatible with
+the strong Coulomb and Froehlich interactions, and with many other independent
+observations in these highly polarizable doped insulators. Remarkably, we also
+quantitatively explain measured critical temperatures and magnitudes of the
+magnetic-field penetration depth. The present work thus represents an ultimate
+proof of the bipolaron theory of high-temperature superconductivity, which
+takes into account essential Coulomb and electron-phonon interactions.",1105.3124v1
+2011-08-12,A model of the T-dependent pseudogap and its competition with superconductivity in copp er oxides,"Results for pseudogaps are obtained from a band model, where the stability of
+the gap depends on the amplitudes of vibrational displacements, or magnetic
+moments, and their coupling to electrons. A one-particle gap is favored by
+normal thermal excitations of phonons or spin waves. Another gap can be
+generated by spontaneous waves at lower temperature, if the electronic energy
+gain overcomes the elastic/magnetic energy needed for increased amplitudes of
+the oscillations. This state is characterized by charge or spin density waves.
+The pseudogap has many features in common with the superconducting gap, and the
+model lends support to the interpretation that the pseudogap is a precursor of,
+and competes with, superconducting pairing.",1108.2626v1
+2011-08-15,Iron Displacements and Magnetoelastic Coupling in the Spin-Ladder Compound BaFe2Se3,"We report long-range ordered antiferromagnetism concomitant with local iron
+displacements in the spin-ladder compound BaFe$_2$Se$_3$. Short-range magnetic
+correlations, present at room temperature, develop into long-range
+antiferromagnetic order below T$_N$ = 256 K, with no superconductivity down to
+1.8 K. Built of ferromagnetic Fe$_4$ plaquettes, the magnetic ground state
+correlates with local displacements of the Fe atoms. These iron displacements
+imply significant magnetoelastic coupling in FeX$_4$-based materials, an
+ingredient hypothesized to be important in the emergence of superconductivity.
+This result also suggests that knowledge of these local displacements is
+essential for properly understanding the electronic structure of these systems.
+As with the copper oxide superconductors two decades ago, our results highlight
+the importance of reduced dimensionality spin ladder compounds in the study of
+the coupling of spin, charge, and atom positions in superconducting materials.",1108.2928v2
+2011-09-09,"Magnetisation Studies of Geometrically Frustrated Antiferromagnets SrLn2O4, with Ln = Er, Dy and Ho","We present the results of susceptibility \chi(T) and magnetisation M(H)
+measurements performed on single crystal samples of the rare-earth oxides
+SrLn2O4 (Ln = Er, Dy and Ho). The measurements reveal the presence of magnetic
+ordering transition in SrHo2O4 at 0.62 K and confirm that SrEr2O4 orders
+magnetically at 0.73 K, while in SrDy2O4 such a transition is absent down to at
+least 0.5 K. The observed ordering temperatures are significantly lower than
+the Curie-Weiss temperatures, \theta_{CW}, obtained from the high-temperature
+linear fits to the 1/\chi(T) curves, which implies that these materials are
+subject to geometric frustration. Strong anisotropy found in the \chi(T) curves
+for a field applied along the different crystallographic directions is also
+evident in the M(H) curves measured both above and below the ordering
+temperatures. For all three compounds the magnetisation plateaux at
+approximately one third of the magnetisation saturation values can be seen for
+certain directions of applied field, which is indicative of field-induced
+stabilisation of a collinear {\it two-up one-down} structure.",1109.2094v1
+2011-10-04,Isospin Dynamics in Sr2IrO4 : Forging Links to Cuprate Superconductivity,"We used resonant inelastic x-ray scattering to reveal the nature of magnetic
+interactions in Sr2IrO4, a 5d transition-metal oxide with a spin-orbit
+entangled ground state and Jeff=1/2 magnetic momemts, referred to as
+'isospins'. The magnon dispersion in Sr2IrO4 is well described by an
+antiferromagnetic Heisenberg model with isospin one-half moments on a square
+lattice, which renders the low-energy effective physics of Sr2IrO4 much akin to
+that in superconducting cuprates. This is further supported by the observation
+of exciton modes in Sr2IrO4 whose dispersion is strongly renormalized by
+magnons, which can be understood by analogy to the hole propagation in the
+background of antiferromagnetically ordered spins in the cuprates.",1110.0759v1
+2012-02-20,Near room-temperature colossal magnetodielectricity and multiglass properties in partially-disordered La2NiMnO6,"We report magnetic, dielectric and magnetodielectric responses of pure
+monoclinic bulk phase of partially-disordered La2NiMnO6, exhibiting a spectrum
+of unusual properties and establish that this system intrinsically is a true
+multiglass with a large magnetodielectric coupling (8-20%) over a wide range of
+temperatures (150 - 300 K). Specifically, our results establish a unique way to
+obtain colossal magnetodielectricity, independent of any striction effects, by
+engineering the asymmetric hopping contribution to the dielectric constant via
+the tuning of the relative spin orientations between neighboring magnetic ions
+in a transition metal oxide system. We discuss the role of anti-site (Ni-Mn)
+disorder in emergence of these unusual properties.",1202.4319v2
+2012-03-14,Oxygen vacancy enhanced room temperature ferromagnetism in Al-doped MgO nanoparticles,"We have investigated the room temperature ferromagnetic order that develops
+in Al-substituted magnesium oxide, Mg(Al)O, nanoparticles with Al fractions of
+up to 5 at.%. All samples, including undoped MgO nanoparticles, exhibit room
+temperature ferromagnetism, with the saturation magnetization reaching a
+maximum of 0.023 emu/g at 2 at.% of Al. X-ray photoelectron spectroscopy
+identifies the presence of oxygen vacancies in both doped and undoped MgO
+nanoparticles, with the vacancy concentration increasing upon vacuum annealing
+of Mg(Al)O, resulting in two-fold enhancement of the saturation magnetization
+for 2 at.% Al-doped MgO. Our results suggest that the oxygen vacancies are
+largely responsible for room temperature ferromagnetism in MgO.",1203.2991v3
+2012-06-05,Spin ordering and electronic texture in the bilayer iridate Sr$_3$Ir$_2$O$_7$,"Through a neutron scattering, charge transport, and magnetization study, the
+correlated ground state in the bilayer iridium oxide Sr$_3$Ir$_2$O$_7$ is
+explored. Our combined results resolve scattering consistent with a high
+temperature magnetic phase that persists above 600 K, reorients at the
+previously defined $T_{AF}=280$ K, and coexists with an electronic ground state
+whose phase behavior suggests the formation of a fluctuating charge or orbital
+phase that freezes below $T^{*}\approx70$ K. Our study provides a window into
+the emergence of multiple electronic order parameters near the boundary of the
+metal to insulator phase transition of the 5d $J_{eff}=1/2$ Mott phase.",1206.1006v2
+2012-06-25,Spin-induced symmetry breaking in orbitally ordered NiCr_2O_4 and CuCr_2O_4,"At room temperature, the normal oxide spinels NiCr_2O_4 and CuCr_2O_4 are
+tetragonally distorted and crystallize in the I4_1/amd space group due to
+cooperative Jahn-Teller ordering driven by the orbital degeneracy of
+tetrahedral Ni$^{2+}$ ($t_2^4$) and Cu$^{2+}$ ($t_2^5$). Upon cooling, these
+compounds undergo magnetic ordering transitions; interactions being somewhat
+frustrated for NiCr_2O_4 but not for CuCr_2O_4. We employ variable-temperature
+high-resolution synchrotron X-ray powder diffraction to establish that at the
+magnetic ordering temperatures there are further structural changes, which
+result in both compounds distorting to an orthorhombic structure consistent
+with the Fddd space group. NiCr_2O_4 exhibits additional distortion, likely
+within the same space group, at a yet-lower transition temperature of $T$ = 30
+K. The tetragonal to orthorhombic structural transition in these compounds
+appears to primarily involve changes in NiO_4 and CuO_4 tetrahedra.",1206.5760v1
+2012-07-25,Advances in ab-initio theory of Multiferroics. Materials and mechanisms: modelling and understanding,"Within the broad class of multiferroics (compounds showing a coexistence of
+magnetism and ferroelectricity), we focus on the subclass of ""improper
+electronic ferroelectrics"", i.e. correlated materials where electronic degrees
+of freedom (such as spin, charge or orbital) drive ferroelectricity. In
+particular, in spin-induced ferroelectrics, there is not only a {\em
+coexistence} of the two intriguing magnetic and dipolar orders; rather, there
+is such an intimate link that one drives the other, suggesting a giant
+magnetoelectric coupling. Via first-principles approaches based on density
+functional theory, we review the microscopic mechanisms at the basis of
+multiferroicity in several compounds, ranging from transition metal oxides to
+organic multiferroics (MFs) to organic-inorganic hybrids (i.e. metal-organic
+frameworks, MOFs)",1207.5918v1
+2012-08-30,Spin-Polarized Ground States and Ferromagnetic Order Induced by Low-Coordinated Surface Atoms and Defects in Nanoscale Magnesium Oxide,"We investigate the effect of low-coordinated surface atoms on the
+defect-induced magnetism in MgO nanocrystallites using hybrid density
+functional theory calculations. It has been demonstrated that when Mg vacancies
+are introduced at the corners of cube-like MgO clusters, a magnetic state
+becomes lower in total energy than the nonmagnetic singlet state by 1-2 eV,
+resulting in the spin-polarized ground state. The spin density is not only
+located at the surrounding O atoms neighbor to the corner Mg vacancy site but
+is also extended to the distant (1 nm or longer) low-coordinated surface O
+atoms along the <110> directions. This directional spin delocalization allows a
+remote Mg vacancy-Mg vacancyinteraction, eventually leading to a spontaneous
+long-range ferromagnetic interaction.",1208.6097v1
+2012-10-24,Theory of the magnetic and metal-insulator transitions in RNiO3 bulk and layered structures,"A slave rotor-Hartree Fock formalism is presented for studying the properties
+of the p-d model describing perovskite transition metal oxides, and a flexible
+and efficient numerical formalism is developed for its solution. The
+methodology is shown to yield, within an unified formulation, the significant
+aspects of the rare earth nickelate phase diagram, including the paramagnetic
+metal state observed for the LaNiO3 and the correct ground-state magnetic order
+of insulating compounds. It is then used to elucidate ground state changes
+occurring as morphology is varied from bulk to strained and un-strained
+thin-film form. For ultrathin films, epitaxial strain and charge-transfer to
+the apical out-of-plane oxygen sites are shown to have significant impact on
+the phase diagram.",1210.6693v1
+2012-11-15,Long-range order and spin-liquid states of polycrystalline Tb$_{2+x}$Ti$_{2-x}$O$_{7+y}$,"Low-temperature states of polycrystalline samples of a frustrated pyrochlore
+oxide Tb$_{2+x}$Ti$_{2-x}$O$_{7+y}$ have been investigated by specific heat,
+magnetic susceptibility, and neutron scattering experiments. We have found that
+this system can be tuned by a minute change of $x$ from a spin-liquid state ($x
+< x_{\text{c}}$) to a partly ordered state with a small antiferromagnetic
+ordering of the order of $0.1 \mu_{\text{B}}$. Specific heat shows a sharp peak
+at a phase transition at $T_{\text{c}}= 0.5$ K for $x=0.005$. Magnetic
+excitation spectra for this sample change from a quasielastic to a gapped type
+through $T_{\text{c}}$. The possibility of a Jahn-Teller transition is
+discussed.",1211.3529v3
+2012-11-27,Theoretical spectroscopy of realistic condensed matter systems,"This thesis is devoted to ab initio calculations of ground and excited state
+properties of different systems within density functional theory and time
+dependent density functional theory. From the numerical point of view we
+implemented an original method in the DP code to calculate the independent
+particle response function. Moreover, we generalized the DP code to the spin
+degree of freedom in order to study the magnetic properties of realistic
+condensed matter systems. We studied reflectance anisotropy and energy loss
+spectra of a clean and oxidized surface, and we performed an analysis of the
+origin of the main spectral features. Thanks to the comparison between
+experimental and theoretical energy loss spectra, we roule out the p(2x1)
+reconstruction for the Si(100) surface. Moreover, in the case of a simple BeH
+molecule we evidenced the problem of correctly describing the excitation
+spectra for open shell systems within the TDDFT framework. In the second part
+of the thesis, we presented the study of the optical properties of magnetic
+systems such as FeS2, CoS2 or NiS2, interesting materials for possible
+technological applications in the growing field of spintronics. Within this
+context we calculated ground state properties and optical condictivity of BCC
+bulk iron, for which we found a nice agreement with available experimental
+data.",1211.6270v1
+2012-12-20,First-Order Superconducting Transition of Sr2RuO4,"By means of the magnetocaloric effect, we examine the nature of the
+superconducting-normal (S-N) transition of Sr2RuO4, a most promising candidate
+for a spin-triplet superconductor. We provide thermodynamic evidence that the
+S-N transition of this oxide is of first order below approximately 0.8 K and
+only for magnetic field directions very close to the conducting plane, in clear
+contrast to the ordinary type-II superconductors exhibiting second-order S-N
+transitions. The entropy release across the transition at 0.2 K is 10% of the
+normal-state entropy. Our result urges an introduction of a new mechanism to
+break superconductivity by magnetic field.",1212.4954v1
+2013-02-09,Current-driven dynamics of chiral ferromagnetic domain walls,"In most ferromagnets the magnetization rotates from one domain to the next
+with no preferred handedness. However, broken inversion symmetry can lift the
+chiral degeneracy, leading to topologically-rich spin textures such as
+spin-spirals and skyrmions via the Dzyaloshinskii-Moriya interaction (DMI).
+Here we show that in ultrathin metallic ferromagnets sandwiched between a heavy
+metal and an oxide, the DMI stabilizes chiral domain walls (DWs) whose spin
+texture enables extremely efficient current-driven motion. We show that spin
+torque from the spin Hall effect drives DWs in opposite directions in
+Pt/CoFe/MgO and Ta/CoFe/MgO, which can be explained only if the DWs assume a
+N\'eel configuration with left-handed chirality. We directly confirm the DW
+chirality and rigidity by examining current-driven DW dynamics with magnetic
+fields applied perpendicular and parallel to the spin spiral. This work
+resolves the origin of controversial experimental results and highlights a new
+path towards interfacial design of spintronic devices.",1302.2257v1
+2013-02-19,High critical current density and low anisotropy in textured Sr1-xKxFe2As2 tapes for high field applications,"From the application point of view, large critical current densities Jc (H)
+for superconducting wires are required, preferably for magnetic fields higher
+than 5 T. Here we show that strong c-axis textured Sr1-xKxFe2As2 tapes with
+nearly isotropic transport Jc were fabricated by an ex-situ powder-in-tube
+(PIT) process. At 4.2 K, the Jc values show extremely weak magnetic field
+dependence and reach high values of 1.7x10^4 A/cm^2 at 10 T and 1.4x10^4 A/cm^2
+at 14 T, respectively, these values are by far the highest ever reported for
+iron based wires and approach the Jc level desired for practical applications.
+Transmission electron microscopy investigations revealed that amorphous oxide
+layers at grain boundaries were significantly reduced by Sn addition which
+resulted in greatly improved intergranular connectivity. Our results
+demonstrated the strong potential of using iron based superconductors for high
+field applications.",1302.4583v1
+2013-03-19,Electronic structure of relativistic Mott insulator Li$_2$RhO$_3$,"Motivated by studies of coexisting electron correlation and spin-orbit
+coupling effect in Na$_2$IrO$_3$ and a recent experiment of its 4d analogue
+Li$_2$RhO$_3$, we performed first-principles calculations of the rhodium oxide
+compound. The experimentally observed ground state of Li$_2$RhO$_3$ can be
+recovered only if both spin-orbit coupling and on-site Coulomb interaction are
+taken into consideration. Within the proper $U$ range for 4d-orbitals
+($2\leqslant U\leqslant 4$ eV), the ground state of Li$_2$RhO$_3$ could be
+either zigzag-AFM or stripy-AFM, both yielding energy gap close to experimental
+observation. Furthermore, the total energy differences between the competing
+magnetic phases are $\leqslant 3$ meV/Rh within $2\leqslant U\leqslant 4$ eV,
+manifesting strong magnetic frustration in the compound. Finally, the phase
+energy of Li$_2$RhO$_3$ cannot be fitted with the two-dimensional
+Heisenberg-Kitaev model involving only the nearest neighbor interactions, and
+we propose that inter-layer interactions may be responsible for the
+discrepancy.",1303.4675v1
+2013-03-28,k.p subband structure of the LaAlO3/SrTiO3 interface,"Heterostructures made of transition metal oxides are new tailor-made
+materials which are attracting much attention. We have constructed a 6-band k.p
+Hamiltonian and used it within the envelope function method to calculate the
+subband structure of a variety of LaAlO3/SrTiO3 heterostructures. By use of
+density functional calculations, we determine the k.p parameters describing the
+conduction band edge of SrTiO3: the three effective mass parameters, L=0.6104
+eV AA^2, M=9.73 eV AA^2, N=-1.616 eV AA^2, the spin orbit splitting
+Delta_SO=28.5 meV and the low temperature tetragonal distortion energy
+splitting Delta_T=2.1 meV. For confined systems we find strongly anisotropic
+non-parabolic subbands. As an application we calculate bands, density of states
+and magnetic energy levels and compare the results to Shubnikov-de Haas quantum
+oscillations observed in high magnetic fields. For typical heterostructures we
+find that electric field strength at the interface of F = 0.1 meV/AA for a
+carrier density of 7.2 10^{12} cm^-2 results in a subband structure that is
+similar to experimental results.",1303.7095v2
+2013-04-04,Ab-initio prediction of magnetoelectricity in infinite-layer CaFeO2 and MgFeO2,"Density functional based simulations are employed to explore magnetoelectric
+effects in iron-based oxides, showing a unique layered structure. We
+theoretically predict CaFeO2 to be a promising magnetoelectric, showing
+magnetically-controlled large electric polarization, possibly even above room
+temperature. The cross coupling between magnetic and dipolar degrees of freedom
+needs, as main ingredients, Fe-site spin-orbit coupling and a spin-dependent O
+p - Fe d hybridization, along with structural constraints related to the
+non-centrosymmetric point group and the peculiar geometry characterized by
+""flattened"" FeO4 tetrahedrons. In order to enhance magnetoelectric effects, we
+performed a materials-design leading to a novel and optimized system, MgFeO2,
+where the larger O4 tetrahedral distortion leads to a stronger polarization.",1304.1228v2
+2013-04-17,Stability and metastability of clusters in a reactive atmosphere: theoretical evidence for unexpected stoichiometries of MgMOx,"By applying a genetic algorithm in a cascade approach of increasing accuracy,
+we calculate the composition and structure of MgMOx clusters at realistic
+temperatures and oxygen pressures. The stable and metastable systems are
+identified by ab initio atomistic thermodynamics. We find that small clusters
+(M <= 5) are in thermodynamic equilibrium when x > M. The non-stoichiometric
+clusters exhibit peculiar magnetic behavior, suggesting the possibility of
+tuning magnetic properties by changing environmental pressure and temperature
+conditions. Furthermore, we show that density-functional theory (DFT) with a
+hybrid exchange-correlation (xc) functional is needed for predicting accurate
+phase diagrams of metal-oxide clusters. Neither a (sophisticated) force field
+nor DFT with (semi)local xc functionals are sufficient for even a qualitative
+prediction.",1304.4803v2
+2013-04-24,"Low temperature ferromagnetism, surface paramagnetism and exchange bias effect in nano-grained alpha-Fe1.4Ga0.6O3 oxide","The compound alpha-Fe1.4Ga0.6O3 has been prepared by mechanical alloying of
+alpha-Fe2O3 and Ga2O3 and subsequent heating of the mechanical alloyed samples
+in vacuum condition. Magnetic ordering of alpha-Fe2O3 has been modified by
+substitution of non-magnetic Ga atoms. The ferromagnetism in alpha-Fe1.4Ga0.6O3
+is more soft and enhanced in comparison to alpha-Fe2O3. M\""ossbauer
+spectroscopy also confirmed enhanced ferromagnetic order in alpha-Fe1.4Ga0.6O3.
+The room temperature soft ferromagnetism by Ga substitution is interesting for
+designing alpha-Fe2O3 based unconventional ferromagnet, which is a great
+challenge to the materials scientists. The alpha-Fe1.4Ga0.6O3 samples also
+exhibited features of exchange bias, low temperature surface paramagnetism, and
+suppression of Morin transition. These features have been affected up to
+certain extent by the nano-sized grains of the samples.",1304.6512v1
+2013-05-27,Collinear and non-collinear spin ground state of wurtzite CoO,"Collinear and non-collinear spin structures of wurtzite phase CoO often
+appearing in nano-sized samples are investigated using first-principles density
+functional theory calculations. We examined the total energy of several
+different spin configurations, electronic structure and the effective magnetic
+coupling strengths. It is shown that the AF3-type antiferromagnetic ordering is
+energetically most stable among possible collinear configurations. Further, we
+found that a novel spiral spin order can be stabilized by including the
+relativistic spin-orbit coupling and the non-collinearity of spin direction.
+Our result suggests that a non-collinear spin ground state can be observed in
+the transition-metal-oxide nanostructures which adds an interesting new aspect
+to the nano-magnetism study.",1305.6496v1
+2013-06-08,Quantum Hall Effects with High Spin-Chern Numbers in Buckled Honeycomb Structure with Magnetic Order,"As a topological insulator, the quantum Hall (QH) effect is indexed by the
+Chern and spin-Chern numbers $\mathcal{C}$ and $\mathcal{C}_{\text{spin}}$. We
+have only $\mathcal{C}_{\text{spin}}=0$ or $\pm \frac{1}{2}$ in conventional QH
+systems. We investigate QH effects in generic monolayer honeycomb systems. We
+search for spin-resolved characteristic patterns by exploring Hofstadter's
+butterfly diagrams in the lattice theory and fan diagrams in the low-energy
+Dirac theory. The Chern and spin-Chern numbers are calculated based on the
+bulk-edge correspondence in the lattice theory and on the Kubo formula in the
+Dirac theory. It is shown that the spin-Chern number can takes an arbitrary
+high value for certain QH systems in coexistence with buckled structure and
+magnetic order. This is a new type of topological insulators. Samples may be
+provided by silicene with ferromagnetic order and transition-metal oxide with
+antiferromagnetic order.",1306.1859v1
+2013-07-09,"Synthesis, Crystal Structure and Physical Properties of Sr2FeOsO6","In the exploration of new osmium based double perovskites, Sr2FeOsO6 is a new
+insertion in the existing family. The polycrystalline compound has been
+prepared by solid state synthesis from the respective binary oxides. PXRD
+analysis shows the structure is pseudo-cubic at room temperature, whereas
+low-temperature synchrotron data refinements reveal the structure to be
+tetragonal, space group I4/m. Heat capacity and magnetic measurements of
+Sr2FeOsO6 indicated the presence of two magnetic phase transitions at T1 = 140
+K and T2 = 67 K. Band structure calculations showed the compound as a narrow
+energy gap semiconductor, which supports the experimental results obtained from
+the resistivity measurements. The present study documents significant
+structural and electronic effects of substituting Fe3+ for Cr3+ ion in
+Sr2CrOsO6.",1307.2586v1
+2013-10-16,Evidence for skyrmions in the high-temperature superconductors,"We claim that the charge density wave recently found by resonant soft x-ray
+scattering in layered copper oxides is the tetragonal symmetry defined by the
+distance between neighbor Cu$^{3+}$ ions in the CuO$_2$ layer that determines
+the critical temperature. We find evidence that this tetragonal symmetry is a
+skyrmionic state, which is responsible for an unusual magnetic order and charge
+flow in the layers that leads to the breaking of the time reversal symmetry
+below the pseudogap line. The core of the skyrmions form pockets of local
+magnetic field piercing the superconducting layers in opposite direction to the
+rest of the unit cell.",1310.4472v1
+2013-11-17,Giant magnetocaloric effect in magnetoelectric Eu1-xBaxTiO3,"We report the magnetic entropy change (Delta Sm) in magnetoelectric
+Eu1-xBaxTiO3 for x = 0.1- 0.9. We find - delta Sm = 11 (40) J/kg.K in x = 0.1
+for a field change of 1 (5) Tesla respectively, which is the largest value
+among all Eu-based oxides. Delta Sm arises from the field-induced suppression
+of the spin entropy of Eu2+:4f7 localized moments. While -delta Sm decreases
+with increasing x, -DeltaSm = 6.58 J/kg.K observed in the high spin diluted
+composition x = 0.9 is larger than that in many manganites. Our results
+indicate that these magnetoelectrics are potential candidates for cryogenic
+magnetic refrigeration.",1311.4161v1
+2013-11-28,"Effect of La Doping on the Crystal Structure, Electric, Magnetic and Morphologic Properties of the BSCCO System","Studies of the doping process can provide a better understanding of the
+superconducting mechanisms in cuprous oxide materials. In this work, we studied
+the doping effects on the crystal structure, electric, morphologic and magnetic
+properties of the BSCCO system with the nominal composition
+$Bi_{1.6}Pb_{0.4}Sr_{(2-x)}RE_xCa_2Cu_3O_{(10-{\delta})}$. Here, the rare earth
+element (RE) was replaced by La in the sites of Sr. The x was ranged from 0.0
+to 2.0, in steps of 0.5. The samples were prepared based on Pechini's method.
+The resulting powder was pressed at room temperature and the pellets were
+submitted to several heat treatments. The characterizations confirm the La in
+the sites of Sr however, the superconducting properties of the sample were not
+improved.",1311.7353v2
+2013-12-04,Magnetic excitation in resonant inelastic x-ray scattering of Sr$_2$IrO$_4$: A localized spin picture,"We study the magnetic excitations in 5d transition-metal oxide Sr$_2$IrO$_4$
+on the basis of the Heisenberg model with small anisotropic terms on a square
+lattice. We calculate the correlation functions by using the Green's functions
+in the spin-wave approximation. The spin waves are split into two modes with
+slightly different energies due to the anisotropic terms. It is shown that the
+spin correlation functions of the y and z components are composed of a single
+peak corresponding to each mode. We analyze the process of resonant inelastic
+x-ray scattering (RIXS) without relying on the fast collision approximation to
+obtain the local scattering operator. The RIXS intensity is derived as a sum of
+the correlation functions of the y and z spin components. We demonstrate that
+the RIXS intensity as a function of energy shows two-peak structure brought
+about by the two modes, which could be observed in the RIXS experiment.",1312.1071v2
+2013-12-05,The Chemical Instability of Na2IrO3 in Air,"We report that Na2IrO3, which has a layered honeycomb iridium oxide
+sublattice interleaved by Na planes, decomposes in laboratory air while
+maintaining the same basic crystal structure. The decomposition reaction was
+monitored by time-dependent powder x-ray diffraction under different ambient
+atmospheres, through which it was determined that it occurs only in the
+simultaneous presence of both CO2 and H2O. A hydrated sodium carbonate is the
+primary decomposition product along with altered Na2IrO3. The diffraction
+signature of the altered Na2IrO3 is quite similar to that of the pristine
+material, which makes the detection of decomposition difficult in a sample
+handled under ordinary laboratory conditions. The decomposed samples show a
+significantly decreased magnetic susceptibility and the disappearance of the
+low temperature antiferromagnetic transition considered to be characteristic of
+the phase. Samples that have never been exposed to air after synthesis display
+a previously unreported magnetic transition at 5K.",1312.1637v1
+2014-02-05,Superconductivity of Cu/CuOx interface formed by shock-wave pressure,"A mixture of powdered Cu and CuO has been subjected to a shock-wave pressure
+of 350 kbar with following quenching of the vacuum-encapsulated product to 77
+K. The ac magnetic susceptibility measurements of the samples have revealed
+metastable superconductivity with Tc = 19.5 K, characterized by glassy dynamics
+of the shielding currents below Tc . Comparison of the ac susceptibility and
+the dc magnetization measurements infers that the superconductivity arises
+within the granular interfacial layer formed between metallic Cu and its oxides
+due to the shock-wave treatment.",1402.0960v1
+2014-02-19,A site-selective antiferromagnetic ground state in layered pnictide-oxide BaTi2As2O,"The electronic and magnetic properties of BaTi$_{2}$As$_{2}$O have been
+investigated using both the first-principles and analytical methods. The
+full-potential linearized augmented plane-wave calculations show that the most
+stable state is a site-selective antiferromagnetic (AFM) metal with a
+$\text{2}\times \text{1}\times \text{1}$ magnetic unit cell containing two
+nonmagnetic Ti atoms and two other Ti atoms with antiparallel moments. Further
+analysis to Fermi surface and spin susceptibility shows that the site-selective
+AFM ground state is driven by the Fermi surface nesting and the Coulomb
+correlation. Meanwhile, the charge density distribution remains uniform,
+suggesting that the phase transition at $200$ K in experiment is a
+spin-density-wave (SDW) transition.",1402.4723v1
+2014-04-24,Large-amplitude spin oscillations triggered by nonequilibrium strongly correlated $t_{2g}$ electrons,"Laser-induced ultrafast (fs) magnetization experiments in antiferromagnets
+have recently attracted large attention, paving the road for inherently fast
+spin dynamics in the THz regime without invoking stray fields. The technical
+importance is emphasized by the rising new research field of antiferromagnetic
+(AFM) spintronics, where superexchange-dominated strongly correlated compounds
+provide an interesting materials playground. An intriguing question is whether
+the Coulomb interaction may be a key to control AFM order on ultrafast time
+scales. Therefore, we study (de)magnetization processes in a time-dependent
+multiorbital Hubbard model, focusing on $t_{2g}$ electrons in a wider doping
+range. Depending on filling, we reveal large-amplitude spin oscillations via
+interaction quenches from the antiferromagnetic or paramagnetic state.
+Nonequilibrium ultrafast spin-orientation effects in prominent correlated
+transition-metal oxides are therefrom predicted.",1404.6118v4
+2014-10-14,The magneto-structural relationship in the tetrahedral spin chain oxide CsCoO$_2$,"We have investigated the structural and magnetic transitions in CsCoO$_2$
+using calorimetric measurements, neutron powder diffraction (NPD), density
+functional theory (DFT) calculations and muon-spin relaxation ($\mu$SR)
+measurements. CsCoO$_2$ exhibits three-dimensional long-range antiferromagnetic
+(AFM) order at 424~K, resulting in antiferromagnetic alignment of chains of
+ferromagnetically ordered Co-Co spin dimers. Although there is no change in
+magnetic structure around a structural transition at $T^{*}=100$~K, the
+resulting bifurcation of corner-shared Co--O--Co bond angles causes a weakening
+of the AFM interaction for one set of bonds along the chains. Consequently, the
+system undergoes a complex freezing out of relaxation processes on cooling.",1410.3686v1
+2014-11-19,Universal domain wall dynamics under electric field in Ta/CoFeB/MgO devices with perpendicular anisotropy,"Electric field effects in ferromagnetic/oxide dielectric structures provide a
+new route to control domain wall (DW) dynamics with low power dissipation.
+However, electric field effects on DW velocities have only been observed so far
+in the creep regime where DW velocities are low due to strong interactions with
+pinning sites. Here, we show gate voltage modulation of DW velocities ranging
+from the creep to the flow regime in Ta/Co40Fe40B20/MgO/TiO2 structures with
+perpendicular magnetic anisotropy. We demonstrate a universal description of
+the role of applied electric fields in the various pinning dependent regimes by
+taking into account an effective magnetic field being linear with the electric
+field. In addition, the electric field effect is found to change sign in the
+Walker regime. Our work opens new opportunities for the study and optimization
+of electric field effect at ferromagnetic metal/insulator interfaces.",1411.5267v2
+2014-12-02,Two-stage magnetic-field-tuned superconductor-insulator transition in underdoped La$_{2-x}$Sr$_{x}$CuO$_{4}$,"In the underdoped pseudogap regime of cuprate superconductors, the normal
+state is commonly probed by applying a magnetic field ($H$). However, the
+nature of the $H$-induced resistive state has been the subject of a long-term
+debate, and clear evidence for a zero-temperature ($T=0$) $H$-tuned
+superconductor-insulator transition (SIT) has proved elusive. Here we report
+magnetoresistance measurements in underdoped La$_{2-x}$Sr$_{x}$CuO$_{4}$,
+providing striking evidence for quantum critical behavior of the resistivity --
+the signature of a $H$-driven SIT. The transition is not direct: it is
+accompanied by the emergence of an intermediate state, which is a
+superconductor only at $T=0$. Our finding of a two-stage $H$-driven SIT goes
+beyond the conventional scenario in which a single quantum critical point
+separates the superconductor and the insulator in the presence of a
+perpendicular $H$. Similar two-stage $H$-driven SIT, in which both disorder and
+quantum phase fluctuations play an important role, may also be expected in
+other copper-oxide high-temperature superconductors.",1412.1134v1
+2015-04-02,High field termination of a Cooper-pair insulator,"We conducted a systematic study of the disorder dependence of the termination
+of superconductivity, at high magnetic fields (B), of amorphous indium oxide
+films. Our lower disorder films show conventional behavior where
+superconductivity is terminated with a transition to a metallic state at a
+well-defined critical field, Bc2. Our higher disorder samples undergo a
+B-induced transition into a strongly insulating state, which terminates at
+higher B's forming an insulating peak. We demonstrate that the B terminating
+this peak coincides with Bc2 of the lower disorder samples. Additionally we
+show that, beyond this field, these samples enter a different insulating state
+in which the magnetic field dependence of the resistance is weak. These results
+provide crucial evidence for the importance of Cooper-pairing in the insulating
+peak regime.",1504.00528v2
+2015-05-22,Charge transfer and hybrid ferroelectricity in (YFeO$_{3}$)$_{n}$/(YTiO$_{3}$)$_{n}$ magnetic superlattices,"Interfaces in oxide heterostructures always provide a fertile ground for
+emergent properties. Charge transfer from a high energy band to a low energy
+opponent is naturally expected, as occurring in semiconductor $p$-$n$
+junctions. In this study, several exceptional physical phenomena have been
+predicted in (YFeO$_3$)$_n$/(YTiO$_3$)$_n$ superlattices. First, the charge
+transfer between these Mott insulators is in opposite to the intuitive band
+alignment scenario. Second, hybrid ferroelectricity with a moderate
+polarization is generated in the $n=2$ magnetic superlattice. Furthermore, the
+ferroelectric-type distortion can persist even if the
+($AB$O$_3$)$_2$/($AB$'O$_3$)$_2$ system turns to be metallic, rending possible
+metallic ferroelectricity.",1505.05978v1
+2015-06-02,Effects of frustration and cyclic exchange on the spin-1/2 Heisenberg antiferromagnet within the self-consistent spin-wave theory,"The relevance of the quasi-two-dimensional spin-1/2 frustrated quantum
+antiferromagnet due to its possibility of modelling the high-temperature
+superconducting parent compounds has resulted in numerous theoretical and
+experimental studies. This paper presents a detailed research of the influence
+of the varying exchange interactions on the model magnetic properties within
+the framework of self-consistent spin-wave theory based on Dyson-Maleev
+representation. Beside the nearest neighbour interaction within the plane, the
+planar frustration up to the third nearest neighbours, cyclic interaction and
+the interlayer coupling are taken into account. The detailed description of the
+elementary spin excitations, staggered magnetization, spin-wave velocity
+renormalization factor and ground-state energy is given. The results are
+compared to the predictions of the linear spin-wave theory and when possible
+also to the second-order perturbative spin-wave expansion results. Finally,
+having at our disposal improved experimental results for the in-plane spin-wave
+dispersion in high-$T_c$ copper oxide $\mbox{La}_2\mbox{CuO}_4$, the
+self-consistent spin-wave theory is applied to that compound in order to
+correct earlier obtained set of exchange parameters and high temperature
+spin-wave dispersion.",1506.00773v1
+2015-06-20,"Common effect of chemical and external pressures on the magnetic properties of $R$CoPO ($R$ = La, Pr, Nd, Sm). II","The direct correspondence between Co band ferromagnetism and structural
+parameters is investigated in the pnictide oxides $R$CoPO for different
+rare-earth ions ($R$ = La, Pr, Nd, Sm) by means of muon-spin spectroscopy and
+{\it ab-initio} calculations, complementing our results published previously
+[G. Prando {\it et al.}, {\it Phys. Rev. B} {\bf 87}, 064401 (2013)]. Both the
+transition temperature to the ferromagnetic phase $T_{_{\textrm{C}}}$ and the
+volume of the crystallographic unit cell $V$ are found to be conveniently tuned
+by the $R$ ionic radius and/or external pressure. A linear correlation between
+$T_{_{\textrm{C}}}$ and $V$ is reported and {\it ab-initio} calculations
+unambiguously demonstrate a full equivalence of chemical and external
+pressures. As such, $R$ ions are shown to be influencing the ferromagnetic
+phase only via the induced structural shrinkage without involving any active
+role from the electronic $f$ degrees of freedom, which are only giving a
+sizeable magnetic contribution at much lower temperatures.",1506.06211v1
+2015-06-23,Novel Spin-Orbital Phases Induced by Orbital Dilution,"We demonstrate that magnetic $3d$ impurities with $S=3/2$ spins and no
+orbital degree of freedom induce changes of spin-orbital order in a $4d^4$ Mott
+insulator with $S=1$ spins. Impurities act either as spin defects which
+decouple from the surrounding ions, or trigger orbital polarons along $3d$-$4d$
+bonds. The $4d$-$4d$ superexchange in the host $J_{\rm host}$ competes with
+$3d$-$4d$ superexchange $J_{\rm imp}$ --- it depends on which orbital is doubly
+occupied. The spin-orbital order within the host is totally modified at doping
+$x=1/4$. Our findings provide new perspective for future theoretical and
+experimental studies of doped transition-metal oxides.",1506.07048v1
+2015-06-24,Direct writing of CoFe alloy nanostructures by focused electron beam induced deposition from a heteronuclear precursor,"Recently, focused electron beam induced deposition has been employed to
+prepare functional magnetic nanostructures with potential in nanomagnetic logic
+and sensing applications by using homonuclear precursor gases like Fe(CO)5 or
+Co2(CO)8. Here we show that an extension towards the fabrication of bi-metallic
+compounds is possible by using a single-source heteronuclear precursor gas. We
+have grown CoFe alloy magnetic nanostructures from the HFeCo3(CO)12 metal
+carbonyl precursor. The compositional analysis indicate that the samples
+contain about 80 at% of metal and 10 at% of carbon and oxygen. Four-probe
+magnetotransport measurements are carried out on nanowires of various sizes
+down to a width of 50 nm, for which the room temperature resistivity of
+43~$\mu\Omega$cm is found. Micro-Hall magnetometry reveals that
+50~nm$\times$250~nm nanobars of the material are ferromagnetic up to the
+highest measured temperature of 250 K. Finally, the TEM microstructural
+investigation shows that the deposits consist of a bcc Co-Fe phase mixed with a
+FeCo2O4 spinel oxide phase with nanograins of about 5 nm diameter.",1506.07311v1
+2015-07-10,New synthesis route and magnetic structure of Tm2Mn2O7 - pyrochlore,"In this work we present a new chemical route to synthesize Tm2Mn2O7
+pyrochlore, a compound which is thermodynamically unstable at ambient pressure.
+Differently from the reported in the past high pressure synthesis of the same
+compound applying oxides as starting materials, we have obtained a pure phase
+Tm2Mn2O7 by a converting TmMnO3 at 1100 C and 1300 bar oxygen pressure. The
+studies of Tm2Mn2O7 performed by a high resolution neutron powder diffraction
+have shown, that a pure pyrochlore cubic phase Tm2Mn2O7 (space group Fd-3m)
+have been obtained. On cooling below 25K there is a transition to a
+ferromagnetically (FM) ordered phase observed with an additional
+antiferromagnetic (AFM) canting suggesting a lowering of the initial cubic
+crystal symmetry. The magnetic transition is accompanied by small but well
+visible magnetostrsiction effect. Using symmetry analysis we have found a
+solution for the AFM structure in the maximal Shubnikov subgroup I41/am'd'.",1507.02830v1
+2015-08-31,Partial spin polarization of conductance in vertical bi-layer nanowire with rectangular and smooth lateral confinement potential,"We simulate the electron transport in vertical bi-layer nanowire which can be
+fabricated in molecular beam epitaxy process with lateral confinement potential
+formed by means of cleaved overgrowth or surface oxidization methods giving
+rectangular and smooth side confinement, respectively. In calculations we take
+into account interaction between charge carriers using DFT within local spin
+density approximation. If magnetic field is perpendicular to the wire axis,
+pseudogaps are opened in energy dispersion relation E(k) what in conjunction
+with spin Zeeman shift of spin-up and spin-down subbands allows for quite high
+spin polarization of conductance. We find that in nanowire with rectangular
+lateral confinement potential, electron density has two maximums localized at
+wire edges in each layers. This modificates strongly all magnetosubbands giving
+up to four energy minimums in lowest subband and considerably diminishes widths
+of pseudogaps what translates into low maximal spin polarization of
+conductance, not exceeding $40\%$. This drawback is absent in wire with smooth
+lateral confinement. However, in order to gain a large spin polarization
+simultaneous tuning of magnetic field as well as the Fermi energies in both
+layers of nanowire are required.",1508.07963v1
+2015-09-02,Pauli Spin Blockade of Heavy Holes in a Silicon Double Quantum Dot,"In this work, we study hole transport in a planar silicon
+metal-oxide-semiconductor based double quantum dot. We demonstrate Pauli spin
+blockade in the few hole regime and map the spin relaxation induced leakage
+current as a function of inter-dot level spacing and magnetic field. With
+varied inter-dot tunnel coupling we can identify different dominant spin
+relaxation mechanisms. Applying a strong out-of-plane magnetic field causes an
+avoided singlet-triplet level crossing, from which the heavy hole g-factor
+$\sim$ 0.93, and the strength of spin-orbit interaction $\sim$ 110 $\mu$eV, can
+be obtained. The demonstrated strong spin-orbit interaction of heavy hole
+promises fast local spin manipulation using only electrical fields, which is of
+great interest for quantum information processing.",1509.00553v1
+2015-10-07,Polar domain walls trigger magnetoelectric coupling,"Interface physics in oxide heterostructures is pivotal in material's science.
+Domain walls (DWs) in ferroic systems are examples of naturally occurring
+interfaces, where order parameter of neighboring domains is modified and
+emerging properties may develop. Here we show that electric tuning of
+ferroelastic domain walls in SrTiO3 leads to dramatic changes of the magnetic
+domain structure of a neighboring magnetic layer (La1/2Sr1/2MnO3) epitaxially
+clamped on a SrTiO3 substrate. We show that by exploiting the resposiveness of
+DWs nanoregions to external stimuli, even in absence of any domain
+contribution, prominent and adjustable macroscopic reactions of neighboring
+layers can be obtained. We conclude that polar DWs, known to exist in other
+materials, can be used to trigger tunable responses and may lead to new ways
+for manipulation of interfacial emerging properties.",1510.02039v1
+2015-10-16,Adjacent Fe-Vacancy Interactions as the Origin of Room Temperature Ferromagnetism in (In$_{1-x}$Fe$_x$)$_2$O$_3$,"Dilute magnetic semiconductors (DMSs) show great promise for applications in
+spin-based electronics, but in most cases continue to elude explanations of
+their magnetic behavior. Here, we combine quantitative x-ray spectroscopy and
+Anderson impurity model calculations to study ferromagnetic Fe-substituted
+In$_2$O$_3$ films, and we identify a subset of Fe atoms adjacent to oxygen
+vacancies in the crystal lattice which are responsible for the observed room
+temperature ferromagnetism. Using resonant inelastic x-ray scattering, we map
+out the near gap electronic structure and provide further support for this
+conclusion. Serving as a concrete verification of recent theoretical results
+and indirect experimental evidence, these results solidify the role of
+impurity-vacancy coupling in oxide-based DMSs.",1510.05030v1
+2015-11-09,Investigation of the magnetic structure and crystal field states of pyrochlore antiferromagnet Nd2Zr2O7,"We present synchrotron x-ray diffraction, neutron powder diffraction and
+time-of-flight inelastic neutron scattering measurements on the rare earth
+pyrochlore oxide Nd2Zr2O7 to study the ordered state magnetic structure and
+cystal field states. The structural characterization by high-resolution
+synchrotron x-ray diffraction confirms that the pyrochlore structure has no
+detectable O vacancies or Nd/Zr site mixing. The neutron diffraction reveals
+long range all-in/all-out antiferromagnetic order below T_N ~ 0.4 K with
+propagation vector k = (0 0 0) and an ordered moment of 1.26(2) \mu_B/Nd at 0.1
+K. The ordered moment is much smaller than the estimated moment of 2.65
+\mu_B/Nd for the local <111> Ising ground state of Nd3+ (J=9/2) suggesting that
+the ordering is partially suppressed by quantum fluctuations. The strong Ising
+anisotropy is further confirmed by the inelastic neutron scattering data which
+reveals a well-isolated dipolar-octupolar type Kramers doublet ground state.
+The crystal field level scheme and ground state wavefunction have been
+determined.",1511.02749v1
+2015-11-28,Spin-orbit torque engineering via oxygen manipulation,"Spin transfer torques allow the electrical manipulation of the magnetization
+at room temperature, which is desirable in spintronic devices such as spin
+transfer torque memories. When combined with spin-orbit coupling, they give
+rise to spin-orbit torques which are a more powerful tool for magnetization
+control and can enrich device functionalities. The engineering of spin-orbit
+torques, based mostly on the spin Hall effect, is being intensely pursued. Here
+we report that the oxidation of spin-orbit torque devices triggers a new
+mechanism of spin-orbit torque, which is about two times stronger than that
+based on the spin Hall effect. We thus introduce a way to engineer spin-orbit
+torques via oxygen manipulation. Combined with electrical gating of the oxygen
+level, our findings may also pave the way towards reconfigurable logic devices.",1511.08868v1
+2016-02-24,Critical behavior of sputter-deposited magnetoelectric antiferromagnetic Cr$_2$O$_3$ films near Néel temperature,"Chromium(III) oxide is a classical collinear antiferromagnet with a linear
+magnetoelectric effect. We are presenting the measurements of the
+magnetoelectric susceptibility $\alpha$ of a sputter-deposited 500-nm film and
+a bulk single-crystal of Cr$_\mathrm{2}$O$_\mathrm{3}$. We investigated the
+magnetic phase-transition and the critical exponent $\beta$ of the sublattice
+magnetization near N\'eel temperature. For the films, an exponent of 0.49(1)
+was found below 293 K, and changed to 1.06(4) near the N\'eel temperature of
+298 K. For the single-crystal, the exponent was constant at 0.324(4). We
+investigated the reversal probability of antiferromagnetic domains during
+magnetoelectric field cooling. For the sputtered films, reversal probability
+was zero above 298 K and stabilized only below 293 K. We attribute this
+behavior to formation of grains during film growth, which gives different
+intergrain and intragrain exchange-coupling energies. For the single-crystal,
+reversal probability was stabilized immediately at the N\'eel temperature of
+307.6 K.",1602.07547v2
+2016-03-10,Local charge variation enhanced spin canting of BiFeO3/La0.7Sr0.3MnO3 heterostructure,"Transition-metal oxides (TMOs) exhibit many emergent phenomena ranging from
+high-temperature super- conductivity and giant magnetoresistance to magnetism
+and ferroelectricity. When TMOs are interfaced with each other, new
+multi-functionalities can arise, which are absent in individual components. In
+this work, we have systematically studied, within a unified double-exchange
+model, the interfacial magnetic response in layered BiFeO3 (BFO) and
+La0.7Sr0.3MnO3 (LSMO) heterostructures. The ferromagnetic/antiferromagnetic
+canting is shown to be enhanced on the interface of BFO by the influence of
+local charge variation. More interestingly, it is found that the spin canting
+in BFO can be further enhanced with deeper penetration depth to the bulk when a
+local oxygen vacancy is placed around the interface.",1603.03107v2
+2016-03-14,Probing the Nuclear Spin-Lattice Relaxation Time at the Nanoscale,"Nuclear spin-lattice relaxation times are measured on copper using magnetic
+resonance force microscopy performed at temperatures down to 42 mK. The low
+temperature is verified by comparison with the Korringa relation. Measuring
+spin-lattice relaxation times locally at very low temperatures opens up the
+possibility to measure the magnetic properties of inhomogeneous electron
+systems realized in oxide interfaces, topological insulators and other strongly
+correlated electron systems such as high-Tc superconductors.",1603.04238v2
+2016-04-22,Multiband behavior and non-metallic low-temperature state of K$_{0.50}$Na$_{0.24}$Fe$_{1.52}$Se$_{2}$,"We report evidence for multiband transport and an insulating low-temperature
+normal state in superconducting K$_{0.50}$Na$_{0.24}$Fe$_{1.52}$Se$_{2}$ with
+$T_{c}\approx 20$ K. The temperature-dependent upper critical field, $H_{c2}$,
+is well described by a two-band BCS model. The normal-state resistance,
+accessible at low temperatures only in pulsed magnetic fields, shows an
+insulating logarithmic temperature dependence as $T \rightarrow 0$ after
+superconductivity is suppressed. This is similar as for high-$T_{c}$ copper
+oxides and granular type-I superconductors, suggesting that the
+superconductor-insulator transition observed in high magnetic fields is related
+to intrinsic nanoscale phase separation.",1604.06793v1
+2016-06-16,Template-Assisted Direct Growth of 1Td/in$^2$ Bit Patterned Media,"We present a method for growing bit patterned magnetic recording media using
+directed growth of sputtered granular perpendicular magnetic recording media.
+The grain nucleation is templated using an epitaxial seed layer which contains
+Pt pillars separated by amorphous metal oxide. The scheme enables the creation
+of both templated data and servo regions suitable for high density hard disk
+drive operation. We illustrate the importance of using a process that is both
+topographically and chemically driven to achieve high quality media.",1606.05370v1
+2016-09-06,How to measure the local Dzyaloshinskii Moriya Interaction in Skyrmion Thin Film Multilayers,"The current driven motion of skyrmions in MnSi and FeGe thinned single
+crystals could be initiated at current densities of the order of $10^6$ A/m,
+five orders of magnitude smaller than for magnetic domain walls. The
+technologically crucial step of replicating these results in thin films has not
+been successful to date, but the reasons are not clear. Elucidating them
+requires analyzing system characteristics at scales of few nm where the key
+Dzyaloshinskii Moriya (DM) interactions vary, and doing so in near application
+conditions, i.e. oxidation protected systems at room temperature. In this
+work's magnetic force microscopy (MFM) studies of magnetron sputtered Ir/Co/Pt
+multilayers we show skyrmions that are smaller than previously observed, are
+not circularly symmetric, and are pinned to 50 nm wide areas of 75 percent
+higher than average DM interaction. This finding matches our measurement of Co
+layer thickness inhomogeneity of the order of $\pm$1.2 atomic monolayers per
+0.6 nm layer, and indicates that layer flatness must be controlled with greater
+precision to preclude skyrmion pinning.",1609.01615v1
+2017-02-27,Determination of oxygen vacancy limit in Mn substituted YSZ ceramics,"The series of Mnx(Y0.148Zr0.852)1-xO2-{\delta} ceramics was systematically
+studied by means of X-ray absorption and emission spectroscopy and DC magnetic
+susceptibility. XAS and XES results show changes in manganese oxidation state
+and a gradual evolution of the local atomic environment around Mn ions upon
+increasing dopants content, which is due to structural relaxation caused by
+growing amount of oxygen vacancies. Magnetic susceptibility measurements reveal
+that Mn3O4 precipitates are formed for x greater than or equal to 0.1 and
+enable independent determination of actual quantity of Mn ions dissolved in YSZ
+solid solution. We show that amount of oxygen vacancies generated by manganese
+doping into YSZ is limited to 0.19 per formula unit.",1702.08361v1
+2017-03-31,(LaTiO$_3$)$_n$/(LaVO$_3$)$_n$ as a model system for unconventional charge transfer and polar metallicity,"At interfaces between oxide materials, lattice and electronic reconstructions
+always play important roles in exotic phenomena. In this study, the density
+functional theory and maximally localized Wannier functions are employed to
+investigate the (LaTiO$_3$)$_n$/(LaVO$_3$)$_n$ magnetic superlattices. The
+electron transfer from Ti$^{3+}$ to V$^{3+}$ is predicted, which violates the
+intuitive band alignment based on the electronic structures of LaTiO$_3$ and
+LaVO$_3$. Such unconventional charge transfer quenches the magnetism of
+LaTiO$_3$ layer mostly and leads to metal-insulator transition in the $n=1$
+superlattice when the stacking orientation is altered. In addition, the
+compatibility among the polar structure, ferrimagnetism, and metallicity is
+predicted in the $n=2$ superlattice.",1703.10748v1
+2018-02-23,Probing the $J_{eff}=0$ ground state and the Van Vleck paramagnetism of the Ir$^{5+}$ ions in the layered Sr$_2$Co$_{0.5}$Ir$_{0.5}$O$_4$,"We report a combined experimental and theoretical x-ray magnetic circular
+dichroism (XMCD) spectroscopy study at the Ir-$L_{2,3}$ edges on the Ir$^{5+}$
+ions of the layered hybrid solid state oxide Sr$_2$Co$_{0.5}$Ir$_{0.5}$O$_4$
+with the K$_2$NiF$_4$ structure. From theoretical simulation of the
+experimental Ir-$L_{2,3}$ XMCD spectrum, we found a deviation from a pure
+$J_{eff}=0$ ground state with an anisotropic orbital-to-spin moment ratio
+($L_x/2S_x$ = 0.43 and $L_z/2S_z$ = 0.78). This deviation is mainly due to
+multiplet interactions being not small compared to the cubic crystal field and
+due to the presence of a large tetragonal crystal field associated with the
+crystal structure. Nevertheless, our calculations show that the energy gap
+between the singlet ground state and the triplet excited state is still large
+and that the magnetic properties of the Ir$^{5+}$ ions can be well described in
+terms of singlet Van Vleck paramagnetism.",1802.08752v1
+2018-04-04,Direct magnetization-polarization coupling in BaCuF$_4$ fluoride,"Despite oxides and some fluorides perovskites have emerged as prototypes of
+multiferroic and magnetoelectric materials, they have not impacted real
+devices. Unfortunately, their working temperatures are very low and the
+magnetoelectric coupling has been reported to be rather small. Herewith, we
+report from first-principles calculations an ideal magnetization reversal
+through polarization switching in BaCuF$_4$ which, according to our results,
+could be achieved close to room temperature. We also show that this ideal
+coupling is driven by a soft mode that combines both, polarization and
+octahedral rotation. The later being directly coupled to the weak
+ferromagnetism of BaCuF$_4$. This, added to its strong Jahn-Teller distortion
+and its orbital ordering, makes this material as a very appealing prototype for
+crystals in the $ABX_4$ family in multifunctional applications.",1804.01476v1
+2019-05-09,A Novel ground state in a new dimer iridate Ba13Ir6O30 with Ir6+(5d3) Ions,"We have synthesized and studied a new iridate, Ba13Ir6O30, with unusual Ir
+oxidation states: 2/3 Ir6+(5d3) ions and 1/3 Ir5+(5d4) ions. Its crystal
+structure features dimers of face-sharing IrO6 octahedra, and IrO6 monomers,
+that are linked via long, zigzag Ir-O-Ba-O-Ir pathways. Nevertheless,
+Ba13Ir6O30 exhibits two transitions at TN1 = 4.7 K and TN2 = 1.6 K. This
+magnetic order is accompanied by a huge Sommerfeld coefficient 200 mJ/mole K
+below TN2, signaling a coexisting frustrated/disordered state persisting down
+to at least 0.05 K. This iridate hosts unusually large Jeff=3/2 degrees of
+freedom, which is enabled by strong spin-orbit interactions (SOI) in the
+monomers with Ir6+ ions and a joint effect of molecular orbitals and SOI in the
+dimers occupied by Ir5+ and Ir6+ ions. Features displayed by the magnetization
+and heat capacity suggest that the combination of covalency, SOI and large
+effective spins leads to highly frustrated ferrimagnetic ordering, possibly
+into a skyrmion crystal, a novelty of this new high-spin iridate.",1905.03891v1
+2020-07-13,Spin polarized STM imaging of nanoscale Néel skyrmions in an SrIrO3/SrRuO3 Perovskite Bilayer,"Spin-polarized scanning tunneling microscopy (SPSTM) was used to directly
+image nanoscale N\'eel skyrmions in a SrIrO3 / SrRuO3 bilayer system that are
+among the smallest reported to date in any system. Off-axis magnetron
+sputtering was used to cap epitaxial films of the oxide ferromagnet SRO with 2
+unit cells of SrIrO3, intended to provide interfacial spin orbit coupling.
+Atomic resolution STM imaging and tunneling spectroscopy were used to identify
+island-like SrIrO3 grains and small regions of bare SrRuO3. Isolated skyrmions
+were only observed in SrIrO3-covered regions of the film, and exhibited a
+distribution of sizes and shapes with an average diameter of 3 nm. We found
+that skyrmions must be fully contained within, but may be smaller than, any
+given SrIrO3 region. Additionally, skyrmions were observed on SrIrO3 islands of
+varying thickness without loss of SPSTM contrast, suggesting the magnetic
+texture lies within the SrIrO3 island rather than the underlying ferromagnetic
+SrRuO3. Density functional theory calculations suggest this could be due to a
+small induced magnetic moment associated with IrO layers in the SrIrO3 film.",2007.06139v1
+2010-05-18,Strength of Correlations in electron and hole doped cuprates,"High temperature superconductivity was achieved by introducing holes in a
+parent compound consisting of copper oxide layers separated by spacer layers.
+It is possible to dope some of the parent compounds with electrons, and their
+physical properties are bearing some similarities but also significant
+differences from the hole doped counterparts. Here, we use a recently developed
+first principles method, to study the electron doped cuprates and elucidate the
+deep physical reasons why their behavior is so different than the hole doped
+materials. We find that electron doped compounds are Slater insulators, e.g. a
+material where the insulating behavior is the result of the presence of
+magnetic long range order. This is in sharp contrast with the hole doped
+materials, where the parent compound is a Mott charge transfer insulator,
+namely a material which is insulating due to the strong electronic correlations
+but not due to the magnetic order.",1005.3095v1
+2013-08-02,"Control of Spin in La(Mn,Zn)AsO Alloy by Carrier Doping","The control of spin without magnetic field is one of challenges in developing
+spintronic devices. In an attempt to solve this problem, we proposed a novel
+hypothetic LaMn0.5Zn0.5AsO alloy from two experimentally synthesized rare earth
+element transition metal arsenide oxides, i.e. LaMnAsO and LaZnAsO. On the
+basis of the first-principles calculations with strong-correlated correction,
+we found that the LaMn0.5Zn0.5AsO alloy is an antiferromagnetic semiconductor
+at ground state, while bipolar magnetic semiconductor at ferromagnetic state.
+Both electron and hole doping in the LaMn0.5Zn0.5AsO alloy induces the
+transition from antiferromagnetic to ferromagnetic, as well as semiconductor to
+half metal. In particular, the spin-polarization direction is switchable
+depending on the doped carrier's type. As carrier doping can be realized easily
+in experiment by applying a gate voltage, the LaMn0.5Zn0.5AsO alloy stands for
+a promising spintronic material to generate and control the spin-polarized
+carriers with electric field.",1308.0439v1
+2013-08-02,Temperature-dependent exchange bias properties of polycrystalline PtxCo1-x/CoO bilayers,"Temperature and PtCo composition dependence of exchange bias in PtxCo1-x/CoO
+bilayers is investigated. It is observed that exchange bias properties,
+blocking temperature and magnetic anisotropy of the PtxCo1-x/CoO thin films are
+strongly affected by the concentration of Pt at the common interface. A
+detailed structural analysis of antiferromagnetic CoO has been done by x-ray
+photoelectron spectroscopy (XPS). The XPS data revealed that CoO layer grows
+with non-stoichiometric behavior which results in other cobalt oxide phases and
+thus lowers blocking temperature for the exchange biased systems. Increase of
+Pt concentration in PtCo layer strengths the exchange bias and thus decreases
+training of the system. It also results in enhancement of growth-induced
+uniaxial magnetic anisotropy and onset of exchange bias at higher temperatures.
+The role of Pt concentration on the interfacial interactions between
+ferromagnetic and antiferromagnetic layers, and the effect of
+superstoichiometric CoO on blocking temperature are also discussed.",1308.0483v1
+2013-08-06,NMR evidence for spin fluctuations in the bilayer nickelate La3Ni2O6,"We report nuclear magnetic resonance data in the bilayer nickelate La3Ni2O6.
+This material belongs to a family of low valence nickel oxides with square
+planar coordination of the Ni ions and is isoelectronic to the high temperature
+superconducting cuprates. Although the three layer nickelate compound exhibits
+a spin-state transition accompanied by antiferromagnetic order, the bilayer
+material shows no phase transition. The NMR data in the bilayer La3Ni2O6 reveal
+the presence of antiferromagnetic spin fluctuations down to 5K that are
+surprisingly similar to those present in the magnetically ordered trilayer
+La4Ni3O8, suggesting a similar electronic structure in the paramagnetic phase
+of both compounds.",1308.1322v1
+2013-08-06,"Superlattice origin of incommensurable density waves in La_{2-x}Ae_xCuO4 (Ae = Ba, Sr)","In line with the Coulomb-oscillator model of superconductivity, loop currents
+of excited 3s electrons from O^2- ions, passing in the CuO2 plane through
+nuclei of nearest-neighbor oxygen quartets, create the antiferromagnetic phase
+of undoped copper oxides. Holes, introduced by alkaline-earth doping of
+La2CuO4, destroy the loop currents, thereby weakening antiferromagnetism until
+it disappears at doping x = 0.02. Further doping of La_2-xAe_xCuO4 gives rise
+to incommensurate free-hole density waves whose wavelength is determined by the
+spacing of a doping superlattice. Modulating the ordering of the ions' magnetic
+moments, the charge-density wave, of incommensurability 2 delta, causes a
+magnetic density wave of incommensurability delta. The formula derived for
+delta(x) is in excellent agreement with data from X-ray diffraction and neutron
+scattering.",1308.1396v2
+2017-01-03,Magnetite nano-islands on silicon-carbide with graphene,"X-ray magnetic circular dichroism (XMCD) measurements of iron nano-islands
+grown on graphene and covered with a Au film for passivation reveal that the
+oxidation through defects in the Au film spontaneously leads to the formation
+of magnetite nano-particles (i.e, $Fe_3$$O_4$). The Fe nano-islands (20 and 75
+monolayers; MLs) are grown on epitaxial graphene formed by thermally annealing
+6H-SiC(0001) and subsequently covered, in the growth chamber, with nominal 20
+layers of Au. Our X-ray absorption spectroscopy and XMCD measurements at
+applied magnetic fields show that the thin film (20 ML) is totally converted to
+magnetite whereas the thicker film (75 ML) exhibits properties of magnetite but
+also those of pure metallic iron. Temperature dependence of the XMCD signal (of
+both samples) shows a clear transition at $T_{\rm V}\approx 120$ K consistent
+with the Verwey transition of bulk magnetite. These results have implications
+on the synthesis of magnetite nano-crystals and also on their regular
+arrangements on functional substrates such as graphene.",1701.00861v1
+2018-05-15,Spin accumulation at nonmagnetic interface induced by direct Rashba Edelstein effect,"Rashba effect describes how electrons moving in an electric field experience
+a momentum dependent magnetic field that couples to the electron angular
+momentum (spin). This physical phenomenon permits the generation of spin
+polarization from charge current (Edelstein effect), which leads to the buildup
+of spin accumulation. Spin accumulation due to Rashba Edelstein effect has been
+recently reported to be uniform and oriented in plane, which has been suggested
+for applications as spin filter device and efficient driving force for
+magnetization switching. Here, we report the X-ray spectroscopy
+characterization Rashba interface formed between nonmagnetic metal (Cu, Ag) and
+oxide (Bi$_{2}$O$_{3}$) at grazing incidence angles. We further discuss the
+generation of spin accumulation by injection of electrical current at these
+Rashba interfaces, and its optical detection by time resolved magneto optical
+Kerr effect. We provide details of our characterization which can be extended
+to other Rashba type systems beyond those reported here.",1805.05523v1
+2012-01-31,Principles of the Field Theory of High Temperature Superconductivity in Underdoped Copper-Oxides,"Here I extend my last work about the origin of the pseudo-gaps in underdoped
+cuprates (arXiv: cond-mat. 1011.3206), to include the mechanism of
+superconductivity. This is done by adapting the formalism of the double
+correlations in systems with nested Fermi surfaces to the semi one dimensional
+system of strings of holes. It is proposed that magnetic interaction is crucial
+for the establishment of the pseudogap and the high temperature
+superconductivity. It is shown that superconductivity disturbs the completeness
+of the strings of holes, and creates fluctuations in their shapes. This, in
+turn, reduces the magnetic interaction and the pseudogap order.",1201.6494v11
+2013-09-12,One-Dimensional Dispersive Magnon Excitation in the Frustrated Spin-2 Chain System Ca3Co2O6,"Using inelastic neutron scattering, we have observed a quasi-one-dimensional
+dispersive magnetic excitation in the frustrated triangular-lattice spin-2
+chain oxide Ca3Co2O6. At the lowest temperature (T = 1.5 K), this magnon is
+characterized by a large zone-center spin gap of ~27 meV, which we attribute to
+the large single-ion anisotropy, and disperses along the chain direction with a
+bandwidth of ~3.5 meV. In the directions orthogonal to the chains, no
+measurable dispersion was found. With increasing temperature, the magnon
+dispersion shifts towards lower energies, yet persists up to at least 150 K,
+indicating that the ferromagnetic intrachain correlations survive up to 6 times
+higher temperatures than the long-range interchain antiferromagnetic order. The
+magnon dispersion can be well described within the predictions of linear
+spin-wave theory for a system of weakly coupled ferromagnetic chains with large
+single-ion anisotropy, enabling the direct quantitative determination of the
+magnetic exchange and anisotropy parameters.",1309.3222v2
+2013-09-17,Strongly Correlated Materials,"Strongly correlated materials are profoundly affected by the repulsive
+electron-electron interaction. This stands in contrast to many commonly used
+materials such as silicon and aluminum, whose properties are comparatively
+unaffected by the Coulomb repulsion. Correlated materials often have remarkable
+properties and transitions between distinct, competing phases with dramatically
+different electronic and magnetic orders. These rich phenomena are fascinating
+from the basic science perspective and offer possibilities for technological
+applications. This article looks at these materials through the lens of
+research performed at Rice University. Topics examined include: Quantum phase
+transitions and quantum criticality in ""heavy fermion"" materials and the iron
+pnictide high temperature superconductors; computational ab initio methods to
+examine strongly correlated materials and their interface with analytical
+theory techniques; layered dichalcogenides as example correlated materials with
+rich phases (charge density waves, superconductivity, hard ferromagnetism) that
+may be tuned by composition, pressure, and magnetic field; and nanostructure
+methods applied to the correlated oxides VO2 and Fe3O4, where metal-insulator
+transitions can be manipulated by doping at the nanoscale or driving the system
+out of equilibrium. We conclude with a discussion of the exciting prospects for
+this class of materials.",1309.4473v1
+2013-09-20,Steadfast perpendicular exchange coupling in an ultrathin CoO/PtFe double-layer: strain and spin orientation,"We report on the exchange coupling and magnetic properties of a strained
+ultrathin CoO/PtFe double-layer with perpendicular magnetic anisotropy. The
+cobalt oxide growth by reactive molecular beam epitaxy on a Pt-terminated
+PtFe/Pt(001) surface gives rise to an hexagonal surface and a monoclinic
+distorted CoO 3nm film at room temperature. This distorted ultrathin CoO layer
+couples with the PtFe(001) layer establishing a robust perpendicular exchange
+bias shift. Soft x-ray absorption spectroscopy provides a full description of
+the spin orientations in the CoO/PtFe doublelayer. The exchange bias shift is
+preserved up to the Neel antiferromagnetic ordering temperature of TN=293 K.
+This unique example of selfsame value for blocking and ordering temperatures,
+yet identical to the bulk ordering temperature, is likely related to the
+original strain induced distortion and strengthened interaction between the two
+well-ordered spin layers.",1309.5288v1
+2014-05-27,"Non-d$^0$ Electric Dipole in FeO$_5$ bipyramid: a New Resource for Quantum Paraelectrics, Ferroelectrics and Multiferroics","Electric polarization in conventional ferroelectric oxides usually involves
+nonmagnetic transition-metal ions with an empty d shell (the d$^0$ rule). Here
+we unravel a new mechanism for local electric dipoles based on magnetic
+Fe$^{3+}$ (3d$^5$) ion violating the d$^0$ rule. The competition between the
+long-range Coulomb interaction and short-range Pauli repulsion in a FeO$_5$
+bipyramid with proper lattice parameters would favor an off-center displacement
+of Fe$^{3+}$ that induces a local electric dipole. The manipulation of this
+kind of non-d$^0$ electric dipoles opens up a new route for generating
+unconventional dielectrics, ferroelectrics, and multiferroics. As a prototype
+example, we show that the non-d$^0$ electric dipoles in ferrimagnetic
+hexaferrites (Ba,Sr)Fe$_{12}$O$_{19}$ lead to a new family of magnetic quantum
+paraelectrics.",1405.6806v1
+2014-06-10,Multiferroic interfaces composed of d0 perovskites oxides,"We investigate the electronic, ferroelectric and magnetic properties of
+KTaO3/PbTiO3 interfaces by using conventional density functional theory (DFT)
+and advanced DFT such as hybrid functional HSE06. We show that doped holes in
+valence bands or electrons in conduction bands give rise to ferromagnetism at
+the interfaces. The ferromagnetic states are ground states for both hole-doped
+(p-type) and electron-doped (n-type) interfaces by comparison with their
+corresponding nonmagnetic and antiferromagnetic states. Carriers (holes or
+electrons) concentrate near the interface to screen the polarization charge and
+thus the concentration of carrier varies with the ferroelectric polarization.
+Furthermore, the interface magnetization, which is nearly proportional to the
+concentration of carrier, can be tuned by ferroelectric polarization reversal,
+leading to strong intrinsic magnetoelectric effects at the interface of
+originally nonmagnetic KTaO3 and PbTiO3. Interestingly, a
+ferromagnetic-nonmagnetic transition tuned by an applied electric field can be
+realized at the p-type interface. This suggests an illuminating approach to
+multiferroic materials beyond conventional single-phase multiferroics and
+multi-phase multiferroics such as ferroelectric/ferromagnet heterostructures.
+The KTaO3/PbTiO3 interfaces may be promising in future multiferroic devices
+applications.",1406.2595v2
+2014-06-16,Infrared dichroism of gold nanorods controlled using a magnetically addressable mesophase,"Gold nanorods have unique optical properties, which make them promising
+candidates for building nano-structured materials using a ""bottom-up"" strategy.
+We formulate stable bulk materials with anisotropic optical properties by
+inserting gold and iron oxide nanorods within a lamellar mesophase.
+Quantitative measurements of the order parameter by modelling the absorbance
+spectra show that the medium is macroscopically aligned in a direction defined
+by an external magnetic field. Under field, the system exhibits significant
+absorption dichroism in the infrared range, at the position of the longitudinal
+plasmon peak of the gold nanorods (about 1200 nm), indicating strong
+confinement of these particles within the water layers of the lamellar phase.
+This approach can yield soft and addressable optical elements.",1406.4014v1
+2016-08-09,High-temperature large-gap quantum anomalous Hall insulator in ultrathin double perovskite films,"Motivated by the goal of realizing topological phases in thin films and
+heterostructures of correlated oxides, we propose here a quantum anomalous Hall
+insulator (QAHI) in ultrathin films of double perovskites based on mixed 3d-5d
+or 3d-4d transition metal ions, grown along the [111] direction. Considering
+the specific case of ultrathin Ba2FeReO6, we present a theoretical analysis of
+an effective Hamiltonian derived from first-principles. We establish that a
+strong spin-orbit coupling at Re site, t2g symmetry of the low-energy d-bands,
+polarity of its [111] orientation of perovskite structure, and mixed 3d-5d
+chemistry results in room temperature magnetism with a robust QAHI state of
+Chern number C=1 and a large band-gap. We uncover and highlight a
+non-relativistic orbital-Rashba-type effect in addition to the spin-orbit
+coupling, that governs this QAHI state. Our prediction of a large topological
+band-gap of ~100 meV in electronic structure, and a magnetic transition
+temperature Tc~300K estimated by Monte Carlo simulations, is expected to
+stimulate experimental efforts at synthesis of such films and enable possible
+practical applications of its dissipationless edge currents.",1608.02950v1
+2017-06-12,Non-equilibrium restoration of duality symmetry in the vicinity of the superconductor-insulator transition,"The magnetic field driven superconductor to insulator transition in thin
+films was theoretically analyzed via a vortex-charge duality transformation
+applied to the Hamiltonian. Vortices condensation was conjectured as the
+underline physical mechanism of the insulating phase. Experimental evidence
+supported duality symmetry across the magnetic-field driven superconductor to
+insulator transition in amorphous Indium Oxide films. Counterintuitively,
+duality symmetry is broken at low temperatures where the insulating phase
+develops strongly non linear current-voltage characteristics. Here, we follow
+the breakdown of duality symmetry down to very low temperatures and demonstrate
+the restoration of duality symmetry out of equilibrium.",1706.03511v2
+2017-10-15,Itinerant ferromagnetism of the Pd-terminated polar surface of PdCoO$_2$,"We study the electronic structure of the Pd-terminated surface of the
+non-magnetic delafossite oxide metal PdCoO$_2$. Combining angle-resolved
+photoemission spectroscopy and density-functional theory, we show how an
+electronic reconstruction driven by surface polarity mediates a Stoner-like
+magnetic instability towards itinerant surface ferromagnetism. Our results
+reveal how this leads to a rich multi-band surface electronic structure, and
+provide spectroscopic evidence for an intriguing sample-dependent coupling of
+the surface electrons to a bosonic mode which we attribute to electron-magnon
+interactions. Moreover, we find similar surface state dispersions in PdCrO$_2$,
+suggesting surface ferromagnetism persists in this sister compound despite its
+bulk antiferromagnetic order.",1710.05392v1
+2017-10-16,Positive-Negative Birefringence in Multiferroic Layered Metasurfaces,"We uncover and identify the regime for a magnetically and ferroelectrically
+controllable negative refraction of light traversing multiferroic, oxide-based
+metastructure consisting of alternating nanoscopic ferroelectric (SrTiO$_2$)
+and ferromagnetic (Y$_3$Fe$_2$(FeO$_4$)$_3$, YIG) layers. We perform analytical
+and numerical simulations based on discretized, coupled equations for the
+self-consistent Maxwell/ferroelectric/ferromagnetic dynamics and obtain a
+biquadratic relation for the refractive index. Various scenarios of ordinary
+and negative refraction in different frequency ranges are analyzed and
+quantified by simple analytical formula that are confirmed by full-fledge
+numerical simulations. Electromagnetic-waves injected at the edges of the
+sample are propagated exactly numerically. We discovered that for particular
+GHz frequencies, waves with different polarizations are characterized by
+different signs of the refractive index giving rise to novel types of phenomena
+such as a positive-negative birefringence effect, and magnetically controlled
+light trapping and accelerations.",1710.05995v1
+2017-10-20,Intercalated europium metal in epitaxial graphene on SiC,"X-ray magnetic circular dichroism (XMCD) reveal the magnetic properties of
+intercalated europium metal under graphene on SiC(0001). Intercalation of Eu
+nano-clusters (average size 2.5 nm) between graphene and SiC substate are
+formed by deposition of Eu on epitaxially grown graphene that is subsequently
+annealed at various temperatures while keeping the integrity of the graphene
+layer. Using sum-rules analysis of the XMCD of Eu M$_{4,5}$ edges at $T = 15$
+K, our samples show paramagnetic-like behavior with distinct anomaly at T
+$\approx$ 90 K which may be related to the N{\`e}el transition, T$_N$ = 91 K,
+of bulk metal Eu. We find no evidence of ferromagnetism due to EuO or
+antiferromagnetism due to Eu$_2$O$_3$ indicating that the graphene layer
+protects the intercalated metallic Eu against oxidation over months of exposure
+to atmospheric environment.",1710.07396v1
+2017-12-26,Electro-optic and magneto-optic photonic devices based on multilayers photonic structures,"In this work we describe different types of photonic structures that allow
+tunability of the photonic band gap upon the application of external stimuli,
+as the electric or magnetic field. We review and compare two porous 1D photonic
+crystals: in the first one a liquid crystal has been infiltrated in the pores
+of the nanoparticle network, while in the second one the optical response to
+the electric field of metallic nanoparticles has been exploited. Then, we
+present a 1D photonic crystal made with indium tin oxide (ITO) nanoparticles,
+and we propose this system for electro-optic tuning. Finally, we describe a
+microcavity with a defect mode that is tuned in the near infrared by the
+magnetic field, envisaging a contact-less magneto-optic switch. These optical
+switches can find applications in ICT and electrochromic windows.",1712.09453v1
+2018-01-04,Tunable magnetic and transport properties of Mn3Ga thin films on Ta/Ru seedlayer,"Hexagonal D019-type Mn3Z alloys that possess large anomalous and
+topological-like Hall effects have attracted much attention due to their great
+potential in the antiferromagnetic spintronic devices. Here, we report the
+preparation of Mn3Ga film in both tetragonal and hexagonal phases with a tuned
+Ta/Ru seed layer on the thermally oxidized Si substrate. A large coercivity
+together with a large anomalous Hall resistivity is found in the Ta-only sample
+with mixed tetragonal phase. By increasing the thickness of Ru layer, the
+tetragonal phase gradually disappears and a relatively pure hexagonal phase is
+obtained in the Ta(5)/Ru(30) buffered sample. Further magnetic and transport
+measurements revealed that the anomalous Hall conductivity nearly vanishes in
+the pure hexagonal sample, while an abnormal asymmetric hump structure emerges
+in the low field region. The extracted additional Hall term is robust in a
+large temperature range and presents a sign reversal above 200K. The abnormal
+Hall properties are proposed to be closely related with the frustrated spin
+structure of D019 Mn3Ga.",1801.01233v1
+2018-01-17,Interference induced enhancement of magneto-optical Kerr effect in ultrathin magnetic films,"We have studied the magneto-optical spectra of ultrathin magnetic films
+deposited on Si substrates coated with an oxide layer (SiOx). We find that the
+Kerr rotation angle and the ellipticity of ~1 nm thick CoFeB thin films, almost
+transparent to visible light, show a strong dependence on the thickness of the
+SiOx layer. The Kerr signal from the 1 nm CoFeB thin film can be larger than
+that of ~100 nm thick CoFeB films for a given SiOx thickness and light
+wavelength. The enhancement of the Kerr signal occurs when optical interference
+takes place within the SiOx layer. Interestingly, under such resonance
+condition, the measured Kerr signal is in some cases larger than the estimation
+despite the good agreement of the measured and calculated reflection amplitude.
+We infer the discrepancy originates from interface states that are distinct
+from the bulk characteristics. These results show that optical interference
+effect can be utilized to study the magneto-optical properties of ultrathin
+films.",1801.05539v1
+2018-09-12,Atomic-Scale Interface Engineering of Majorana Edge Modes in a 2D Magnet-Superconductor Hybrid System,"Topological superconductors are predicted to harbor exotic boundary states -
+Majorana zero-energy modes - whose non-Abelian braiding statistics present a
+new paradigm for the realization of topological quantum computing. Using
+low-temperature scanning tunneling spectroscopy (STS), we here report on the
+direct real-space visualization of chiral Majorana edge states in a monolayer
+topological superconductor, a prototypical magnet-superconductor hybrid system
+comprised of nano-scale Fe islands of monoatomic height on a
+Re(0001)-O(2$\times$1) surface. In particular, we demonstrate that interface
+engineering by an atomically thin oxide layer is crucial for driving the hybrid
+system into a topologically non-trivial state as confirmed by theoretical
+calculations of the topological invariant, the Chern number.",1809.04503v1
+2018-09-21,Electronic correlations and competing orders in multiorbital dimers: a cluster DMFT study,"We investigate the violation of the first Hund's rule in 4$d$ and 5$d$
+transition metal oxides that form solids of dimers. Bonding states within these
+dimers reduce the magnetization of such materials. We parametrize the dimer
+formation with realistic hopping parameters and find not only regimes, where
+the system behaves as a Fermi liquid or as a Peierls insulator, but also
+strongly correlated regions due to Hund's coupling and its competition with the
+dimer formation. The electronic structure is investigated using the cluster
+dynamical mean-field theory for a dimer in the two-plane Bethe lattice with two
+orbitals per site and $3/8$-filling, that is three electrons per dimer. It
+reveals dimer-antiferromagnetic order of a high-spin (double exchange) state
+and a low-spin (molecular orbital) state. At the crossover region we observe
+the suppression of long-range magnetic order, fluctuation enhancement and
+renormalization of electron masses. At certain interaction strengths the system
+becomes an incoherent antiferromagnetic metal with well defined local moments.",1809.07989v1
+2018-09-26,Eigenenergies of excitonic giant-dipole states in cuprous oxide,"In this work we present the eigenspectra of a novel species of Wannier
+excitons when exposed to crossed electric and magnetic fields. In particular,
+we compute the eigenenergies of giant-dipole excitons in
+$\textrm{Cu}_2\textrm{O}$ in crossed fields. In our theoretical approach, we
+calculate the excitonic spectra within both an approximate as well as a
+numerically exact approach for arbitrary field configurations. We verify that
+stable bound excitonic giant-dipole states are only possible in the strong
+magnetic field limit, as this is the only regime providing sufficiently deep
+potential wells for their existence. Comparing both analytic as well as
+numerical calculations, we obtain excitonic giant-dipole spectra with level
+spacings in the range of $0.6\ldots100\, \mu \textrm{eV}$.",1809.10039v1
+2018-08-31,The Changed Crystal Filed of Gd3+ in Natural Zircon with Heat Treatment in Oxidizing and Reducing Atmosphere Monitor by ESR Spectroscopy,"The main purpose of this research is dedicated to the ESR study of the
+impurity ions such as Gd3+ in the natural zircon crystal because the presence
+of the impurity ions in the crystal usually causes color in crystal. The Zeeman
+interaction, the weak hyperfine interaction and the crystal field interaction
+due to the environments of the impurity ions will be calculated. Furthermore,
+the relation between the resonance magnetic field positions in the ESR spectra
+and the applied magnetic field directions will reflect the impurity ion site
+symmetry. The change in the crystal field parameters of heat-treated zircon at
+different atmospheres were related to the change in the color of zircon.",1810.00941v1
+2018-10-24,Tuning from failed superconductor to failed insulator with magnetic field,"Do charge modulations compete with electron pairing in high-temperature
+copper-oxide superconductors? We investigated this question by suppressing
+superconductivity in a stripe-ordered cuprate compound at low temperature with
+high magnetic fields. With increasing field, loss of three-dimensional
+superconducting order is followed by reentrant two-dimensional
+superconductivity and then an ultra-quantum metal phase. Circumstantial
+evidence suggests that the latter state is bosonic and associated with the
+charge stripes. These results provide experimental support to the theoretical
+perspective that local segregation of doped holes and antiferromagnetic spin
+correlations underlies the electron-pairing mechanism in cuprates.",1810.10646v2
+2018-10-30,Discovery of Ordered Vortex Phase in Multiferroic Oxide Superlattices,"Ferroics, characterized by a broken symmetry state with nonzero elastic,
+polar, or magnetic order parameters $\vec{u}$, are recognized platforms for
+staging and manipulating topologically-protected structures as well as for
+detecting unconventional topological phenomena. The unrealized possibility of
+producing ordered topological phases in magnetoelectric multiferroics,
+exhibiting coupled magnetic and polar order parameters, is anticipated to
+engender novel functionality and open avenues for manipulating topological
+features. Here, we report the discovery of an ordered $\pi_1$-$S_\infty$ vortex
+phase within single-phase magnetoelectric multiferroic BiFeO$_3$. The phase,
+characterized by positive topological charge and chiral staggering, is realized
+in coherent TbScO$_3$ and BiFeO$_3$ superlattices and established via the
+combination of direct- and Fourier-space analyses. Observed order-parameter
+morphologies are reproduced with a field model describing the local
+order-parameter stiffness and competing non-local dipole-dipole interactions.
+Anisotropies canting the order parameter towards $\left<100\right>$ suppress
+chiral staggering and produced a competing $\pi_1$-$C_{\infty v}$ vortex phase
+in which cores are centered.",1810.12895v1
+2019-06-26,k-Resolved electronic structure of buried heterostructure and impurity systems by soft-X-ray ARPES,"Angle-resolved photoelectron spectroscopy (ARPES) is the main experimental
+tool to explore electronic structure of solids resolved in the electron
+momentum k . Soft-X-ray ARPES (SX-ARPES), operating in a photon energy range
+around 1 keV, benefits from enhanced probing depth compared to the conventional
+VUV-range ARPES, and elemental/chemical state specificity achieved with
+resonant photoemission. These advantages make SX-ARPES ideally suited for
+buried heterostructure and impurity systems, which are at the heart of current
+and future electronics. These applications are illustrated here with a few
+pioneering results, including buried quantum-well states in semiconductor and
+oxide heterostructures, their bosonic coupling critically affecting electron
+transport, magnetic impurities in diluted magnetic semiconductors and
+topological materials, etc. High photon flux and detection efficiency are
+crucial for pushing the SX-ARPES experiment to these most photon-hungry cases.",1906.11025v1
+2019-06-28,Anomalous Hall and Nernst effects in a two-dimensional electron gas with an anisotropic cubic Rashba spin-orbit interaction,"The anomalous Hall and Nernst effects are considered theoretically within
+Matsubara-Green's function formalism. The effective Hamiltonian of a magnetized
+two-dimensional electron gas with cubic Rashba spin-orbit interaction may
+describe transport properties of electronic states at the interfaces or
+surfaces of perovskite oxides or another type of heterostructures that, due to
+symmetry, may be described by the same effective model. In the quasi-ballistic
+limit, both effects are determined by the topological (Fermi sea) contribution
+whereas the states at the Fermi level gives a negligibly small response. For a
+wide range of parameters describing the considered system, the anomalous Nernst
+conductivity reveals a change of the sign before the magnetic phase transition.",1906.12190v1
+2019-06-28,"Exploring the structural , electronic and magnetic properties of cation ordered 3d-5d double perovskite Bi$_2$FeReO$_6$ and Bi$_2$FeIrO$_6$ thin-films from first-principles","We report a first-principles study of Bi-based 3$d$-5$d$ ordered double
+perovskite oxides (A$_2$BB$^\prime$O$_6$) with a 3$d$ atom (Fe) at the B-site
+and 5$d$ atoms (Re,Ir) at the B$^\prime$-site while keeping highly polarizable
+ions (Bi$^{3+}$) at the A-site. We find that, under coherent heteroepitaxy,
+Bi$_2$FeReO$_6$} exhibits a strain-driven anti-ferromagnetic insulator to
+ferrimagnetic semi-metal transition, while Bi$_2$FeIrO$_6$ shows correlation
+driven ferromagnetic insulator to ferrimagnetic half-metal transition with
+calculated magnetic moments of 5 $\mu_B$/f.u. and 3 $\mu_B$/f.u., respectively.
+These properties along with the low band gaps in the insulating phases make the
+compounds appealing for spintronics applications. Furthermore, in
+Bi$_2$FeIrO$_6$, the conduction and valence states are localized on different
+transition metal sublattices implying more efficient electron-hole separation
+upon photoexcitation, a desirable feature for photovoltaic applications.",1907.00041v1
+2019-09-16,Two-dimensional transition metal oxides Mn2O3 realized quantum anomalous Hall effect,"The quantum anomalous Hall effect is a intriguing topological nontrivial
+phase arising from spontaneous magnetization and spin-orbit coupling. However,
+the tremendously harsh realizing requirements of the quantum anomalous Hall
+effects in magnetic topological insulators of Cr or V-doped (Bi,Sb)2Te3 film,
+hinder its practical applications. Here, we use first principles calculations
+to predict that the three Mn2O3 structure is an intrinsic ferromagnetic Chern
+insulator. Remarkably, a quantum anomalous Hall phase of Chern number C = -2 is
+found, and there are two corresponding gapless chiral edge states appearing
+inside the bulk gap. More interestingly, only a small tensile strain is needed
+to induce the phase transition from Cmm2 and C222 phase to P6/mmm phase.
+Meanwhile, a topological quantum phase transition between a quantum anomalous
+Hall phase and a trivial insulating phase can be realize. The combination of
+these novel properties renders the two-dimensional ferromagnet a promising
+platform for high effciency electronic and spintronic applications.",1909.07019v3
+2019-09-24,"Magnetism of (LaCoO$_3$)$_n$+(LaTiO$_3$)$_n$ superlattices with $n=1,2$","LaCoO$_3$ provides a poignant example of a transition metal oxide where the
+cobalt cations display multiple spin states and spin transitions and which
+continues to garner substantial attention. In this work, we describe first
+principles studies, based on DFT+$U$ theory, of superlattices containing
+LaCoO$_3$, specifically (LaCoO$_3$)$_n$+(LaTiO$_3$)$_n$ for $n=1,2$. The
+superlattices show strong electron transfer from Ti to Co resulting in
+Co$^{2+}$, significant structural distortions and a robust orbital polarization
+of Co$^{2+}$. We predict high-spin Co$^{2+}$ and a checkerboard or G-type
+antiferromagnetic (AFM) ground state. We provide a detailed analysis of the
+magnetic interactions and phases in the superlattices. We predict that
+ferromagnetic order on the Co${2+}$ can be stabilized by hole doping (e.g.,
+replacing La by Sr) which is rather unusual for Co$^{2+}$ cations.",1909.11007v1
+2019-10-30,"Emergence of Griffiths phase, re-entrant cluster glass,metamagnetic transition and field induced unusual spin dynamics in Tb2CoMnO6","The structural and magnetic properties of double perovskiteTb2CoMnO6 have
+been investigated. Electronic structure analysis by XPS study reveals the
+presence of mixed oxidation state (Mn4+/Mn3+ and Co2+/Co3+) of B-site ions. The
+dc and ac magnetization measurements reveal different interesting phases such
+as Griffith phase, re-entrant spin glass, metamagnetic steps, Hopkinson like
+peak and also unusual slow relaxation. The M-H curve indicates the presence of
+competing AFM/FM interactions. The disorder in Tb2CoMnO6 leads to spin
+frustration at low temperature giving rise to the re-entrant spin glass.
+Moreover, the field-dependent ac susceptibility studies unraveled the presence
+of Hopkinson like peak associated with the domain wall motion and the large
+anisotropy field. The further study yielded that the relaxation associated with
+this peak is unusually slow.",1910.13734v1
+2020-02-26,Gate-tuned Anomalous Hall Effect Driven by Rashba Splitting in Intermixed LaAlO3/GdTiO3/SrTiO3,"The Anomalous Hall Effect (AHE) is an important quantity in determining the
+properties and understanding the behavior of the two-dimensional electron
+system forming at the interface of SrTiO3-based oxide heterostructures. The
+occurrence of AHE is often interpreted as a signature of ferromagnetism, but it
+is becoming more and more clear that also paramagnets may contribute to AHE. We
+studied the influence of magnetic ions by measuring intermixed
+LaAlO3/GdTiO3/SrTiO3 at temperatures below 10 K. We find that, as function of
+gate voltage, the system undergoes a Lifshitz transition, while at the same
+time an onset of AHE is observed. However, we do not observe clear signs of
+ferromagnetism. We argue the AHE to be due to the change in Rashba spin-orbit
+coupling at the Lifshitz transition and conclude that also paramagnetic moments
+which are easily polarizable at low temperatures and high magnetic filds lead
+to the presence of AHE, which needs to be taken into account when extracting
+carrier densities and mobilities.",2002.11408v1
+2020-12-18,Spin and charge order in doped spin-orbit coupled Mott insulators,"We study a two-dimensional single band Hubbard Hamiltonian with antisymmetric
+spin-orbit coupling. We argue that this is the minimal model to understand the
+electronic properties of locally non-centrosymmetric transition-metal (TM)
+oxides such as Sr$_2$IrO$_4$. Based on exact diagonalizations of small clusters
+and the random phase approximation, we investigate the correlation effects on
+charge and magnetic order as a function of doping and of the TM-oxygen-TM bond
+angle $\theta$. For small doping and $\theta$ $\lesssim$ $15^\circ$ we find
+dominant commensurate in-plane antiferromagnetic fluctuations while
+ferromagnetic fluctuations dominate for $\theta$ $\gtrsim$ $25^\circ$.
+Moderately strong nearest-neighbor Hubbard interactions can also stabilize a
+charge density wave order. Furthermore, we compare the dispersion of magnetic
+excitations for the hole-doped case to resonant inelastic X-ray scattering data
+and find good qualitative agreement.",2012.10479v1
+2012-05-22,"Thickness dependence of magnetic properties of (Ga,Mn)As","We report on a monotonic reduction of Curie temperature in dilute
+ferromagnetic semiconductor (Ga,Mn)As upon a well controlled
+chemical-etching/oxidizing thinning from 15 nm down to complete removal of the
+ferro- magnetic response. The effect already starts at the very beginning of
+the thinning process and is accompanied by the spin reorientation transition of
+the in-plane uniaxial anisotropy. We postulate that a negative gradient along
+the growth direction of self-compensating defects (Mn interstitial) and the
+presence of surface donor traps gives quantitative account on these effects
+within the p-d mean field Zener model with adequate mod- ifications to take a
+nonuniform distribution of holes and Mn cations into account. The described
+here effects are of practical importance for employing thin and ultrathin
+layers of (Ga,Mn)As or relative compounds in concept spintronics devices, like
+resonant tunneling devices in particular.",1205.4824v1
+2017-05-12,Intricacies of the Co$^{3+}$ spin state in Sr$_2$Co$_{0.5}$Ir$_{0.5}$O$_4$: an x-ray absorption and magnetic circular dichroism study,"We report on a combined soft x-ray absorption and magnetic circular dichroism
+(XMCD) study at the Co-$L_{3,2}$ on the hybrid 3$d$/5$d$ solid state oxide
+Sr$_2$Co$_{0.5}$Ir$_{0.5}$O$_4$ with the K$_2$NiF$_4$ structure. Our data
+indicate unambiguously a pure high spin state $(S=2)$ for the Co$^{3+}$
+(3$d^6$) ions with a significant unquenched orbital moment $L_z/2S_z=0.25$
+despite the sizeable elongation of the CoO$_6$ octahedra. Using quantitative
+model calculations based on parameters consistent with our spectra, we have
+investigated the stability of this high spin state with respect to the
+competing low spin and intermediate spin states.",1705.04550v1
+2017-05-23,"Unexpected 3+ valence of iron in FeO$_2$, a geologically important material lying ""in between"" oxides and peroxides","Recent discovery of pyrite FeO$_2$, which can be an important ingredient of
+the Earth's lower mantle and which in particular may serve as an extra source
+of water in the Earth's interior, opens new perspectives for geophysics and
+geochemistry, but this is also an extremely interesting material from physical
+point of view. We found that in contrast to naive expectations Fe is nearly 3+
+in this material, which strongly affects its magnetic properties and makes it
+qualitatively different from well known sulfide analogue - FeS$_2$. Doping,
+which is most likely to occur in the Earth's mantle, makes FeO$_2$ much more
+magnetic. In addition we show that unique electronic structure places FeO$_2$
+""in between"" the usual dioxides and peroxides making this system interesting
+both for physics and solid state chemistry.",1705.08085v2
+2017-09-11,"The effect of double counting, spin density, and Hund interaction in the different DFT+$U$ functionals","A systematic comparative study has been performed to better understand
+DFT$+U$ (density functional theory + $U$) method. We examine the effect of
+choosing different double counting and exchange-correlation functionals. The
+calculated energy distribution and the Hund-$J$ dependence of potential profile
+for representative configurations clearly show the different behaviors of each
+DFT$+U$ formalism. In particular, adopting spin-dependent exchange-correlation
+functionals likely leads to undesirable magnetic solution. Our analyses are
+further highlighted by real material examples ranging from insulating oxides
+(MnO and NiO) to metallic magnetic systems (SrRuO$_3$ and BaFe$_2$As$_2$). The
+current work sheds new light on understanding DFT$+U$ and provides a guideline
+to use the related methods.",1709.03214v2
+2017-09-13,Vortex Variable Range Hopping in a Conventional Superconducting Film,"The behavior of a disordered amorphous thin film of superconducting Indium
+Oxide has been studied as a function of temperature and magnetic field applied
+perpendicular to its plane. A superconductor-insulator transition has been
+observed, though the isotherms do not cross at a single point. The curves of
+resistance vs. temperature on the putative superconducting side of this
+transition, where the resistance decreases with decreasing temperature, obey
+two-dimensional Mott variable-range hopping of vortices over wide ranges of
+temperature and resistance. To estimate the parameters of hopping, the film is
+modeled as a granular system and the hopping of vortices is treated in a manner
+analogous to hopping of charges. The reason the long range interaction between
+vortices over the range of magnetic fields investigated does not lead to a
+stronger variation of resistance with temperature than that of two-dimensional
+Mott variable-range hopping remains unresolved.",1709.04128v2
+2017-09-25,Exfoliation and van der Waals heterostructure assembly of intercalated ferromagnet Cr1/3TaS2,"Ferromagnetic van der Waals (vdW) materials are in demand for spintronic
+devices with all-two-dimensional-materials heterostructures. Here, we
+demonstrate mechanical exfoliation of magnetic-atom-intercalated transition
+metal dichalcogenide Cr1/3TaS2 from its bulk crystal; previously such
+intercalated materials were thought difficult to exfoliate. Magnetotransport in
+exfoliated tens-of-nanometres-thick flakes revealed ferromagnetic ordering
+below its Curie temperature TC ~ 110 K as well as strong in-plane magnetic
+anisotropy; these are identical to its bulk properties. Further, van der Waals
+heterostructure assembly of Cr1/3TaS2 with another intercalated ferromagnet
+Fe1/4TaS2 is demonstrated using a dry-transfer method. The fabricated
+heterojunction composed of Cr1/3TaS2 and Fe1/4TaS2 with a native Ta2O5 oxide
+tunnel barrier in between exhibits tunnel magnetoresistance (TMR), revealing
+possible spin injection and detection with these exfoliatable ferromagnetic
+materials through the vdW junction.",1709.08313v1
+2017-09-25,Electrically detected magnetic resonance of carbon dangling bonds at the Si-face 4H-SiC/SiO$_2$ interface,"SiC based metal-oxide-semiconductor field-effect transistors (MOSFETs) have
+gained a significant importance in power electronics applications. However,
+electrically active defects at the SiC/SiO$_2$ interface degrade the ideal
+behavior of the devices. The relevant microscopic defects can be identified by
+electron paramagnetic resonance (EPR) or electrically detected magnetic
+resonance (EDMR). This helps to decide which changes to the fabrication process
+will likely lead to further increases of device performance and reliability.
+EDMR measurements have shown very similar dominant hyperfine (HF) spectra in
+differently processed MOSFETs although some discrepancies were observed in the
+measured $g$-factors. Here, the HF spectra measured of different SiC MOSFETs
+are compared and it is argued that the same dominant defect is present in all
+devices. A comparison of the data with simulated spectra of the C dangling bond
+(P$_\textrm{bC}$) center and the silicon vacancy (V$_\textrm{Si}$) demonstrates
+that the P$_\textrm{bC}$ center is a more suitable candidate to explain the
+observed HF spectra.",1709.08664v1
+2018-08-14,Engineering the spin couplings in atomically crafted spin chains on an elemental superconductor,"Magnetic atoms on a superconductor give rise to Yu-Shiba-Rusinov (YSR) states
+within the superconducting energy gap. A spin chain of magnetic adatoms on an
+s-wave superconductor may lead to topological superconductivity accompanied by
+the emergence of Majorana modes at the chain ends. For their usage in quantum
+computation, it is a prerequisite to artificially assemble the chains and
+control the exchange couplings between the spins in the chain and in the
+substrate. Here, using a scanning tunneling microscope tip, we demonstrate
+engineering of the energy levels of the YSR states by placing interstitial Fe
+atoms in close proximity to adsorbed Fe atoms on an oxidized Ta surface. Based
+on this prototype platform, we show that the interaction within a long chain
+can be strengthened by linking the adsorbed Fe atoms with the interstitial
+ones. Our work adds an important step towards the controlled design and
+manipulation of Majorana end states.",1808.04641v1
+2019-02-12,Ultra-low damping in lift-off structured yttrium iron garnet thin films,"We show that using maskless photolithography and the lift-off technique,
+patterned yttrium iron garnet thin films possessing ultra-low Gilbert damping
+can be accomplished. The films of 70 nm thickness were grown on (001)-oriented
+gadolinium gallium garnet by means of pulsed laser deposition, and they exhibit
+high crystalline quality, low surface roughness, and the effective
+magnetization of 127 emu/cm3. The Gilbert damping parameter is as low as
+5x10-4. The obtained structures have well-defined sharp edges which along with
+good structural and magnetic film properties pave a path in the fabrication of
+high-quality magnonic circuits and oxide-based spintronic devices.",1902.04605v1
+2019-04-03,"Tetramer Orbital-Ordering induced Lattice-Chirality in Ferrimagnetic, Polar MnTi2O4","Using density-functional theory calculations and experimental investigations
+on structural, magnetic and dielectric properties, we have elucidated a unique
+tetragonal ground state for MnTi2O4, a Ti^{3+} (3d^1)-ion containing
+spinel-oxide. With lowering of temperature around 164 K, cubic MnTi2O4
+undergoes a structural transition into a polar P4_1 tetragonal structure and at
+further lower temperatures, around 45 K, the system undergoes a paramagnetic to
+ferrimagnetic transition. Magnetic superexchange interactions involving Mn and
+Ti spins and minimization of strain energy associated with co-operative
+Jahn-Teller distortions plays a critical role in stabilization of the unique
+tetramer-orbital ordered ground state which further gives rise to lattice
+chirality through subtle Ti-Ti bond-length modulations.",1904.01792v1
+2019-04-11,Triangular array of iron-oxide nanoparticles: A simulation study of intra- and inter-particle magnetism,"A study of spherical maghemite nanoparticles on a two dimensional triangular
+array was carried out using a stochastic Landau-Lifshitz-Gilbert (sLLG)
+approach. The simulation method was first validated with a triangular array of
+simple dipoles, where results show the expected phase transition to a
+ferromagnetic state at a finite temperature. The ground state exhibited a
+continuous degeneracy that was lifted by an order-from-disorder mechanism at
+infinitesimal temperatures with the appearance of a six-fold planar anisotropy.
+The nanoparticle array consisted of 7.5 nm diameter maghemite spheres with
+bulk-like superexchange interactions between Fe-ions in the core, and weaker
+exchange between surface Fe-ions and a radial anisotropy. The triangular
+nanoparticle array ordered at the same reduced temperature as the simple dipole
+array, but exhibited different behaviour at low temperatures due to the surface
+anisotropy. We find that the vacancies on the octahedral sites in the
+nanoparticles combine with the surface anisotropy to produce an effective
+random temperature-dependent anisotropy for each particle. This leads to a
+reduction in the net magnetization of the nanoparticle array at zero
+temperature compared to the simple dipole array.",1904.05515v1
+2019-04-11,Study of soft/hard bimagnetic CoFe2/CoFe2O4 nanocomposite,"We report an experimental study of the bimagnetic nanocomposites
+CoFe2/CoFe2O4.The precursor material, CoFe2O4 was prepared using the
+conventional stoichiometric combustion method. The nanocomposite CoFe2/CoFe2O4
+was obtained by total reduction of CoFe2O4 using a thermal treatment at 350oC
+in H2 atmospheres following a partial oxidation in O2 atmospheres at 380oC
+during 120; 30; 15, 10, and 5 min. The X-ray diffraction and Mossbauer
+spectroscopy confirmed the formation the material CoFe2/CoFe2O4 The magnetic
+hysteresis with different saturation magnetization confirms the formation of
+the CoFe2/CoFe2O4 with different content of CoFe2O4. The high energy milling to
+the precursor material increase the coercivity from 1.0 to 3.3 kOe, however the
+same effect was not observed to the CoFe2/CoFe2O4 material.",1904.05984v1
+2019-07-31,Perspective: Heusler interfaces -- opportunities beyond spintronics?,"Heusler compounds, in both cubic and hexagonal polymorphs, exhibit a
+remarkable range of electronic, magnetic, elastic, and topological properties,
+rivaling that of the transition metal oxides. To date, research on these
+quantum materials has focused primarily on bulk magnetic and thermoelectric
+properties or on applications in spintronics. More broadly, however, Heuslers
+provide a platform for discovery and manipulation of emergent properties at
+well-defined crystalline interfaces. Here, motivated by advances in the
+epitaxial growth of layered Heusler heterostructures, I present a vision for
+Heusler interfaces, focusing on the frontiers and challenges that lie beyond
+spintronics. The ability to grow these materials epitaxially on technologically
+important semiconductor substrates, such as GaAs, Ge, and Si, provides a direct
+path for their integration with modern electronics. Further advances will
+require new methods to control the stoichiometry and defects to ""electronic
+grade"" quality, and to control the interface abruptness and ordering at the
+atomic scale.",1908.00101v1
+2019-08-14,Spin-orbital glass transition in a model of a frustrated pyrochlore magnet without quenched disorder,"We show theoretically that spin and orbital degrees of freedom in the
+pyrochlore oxide Y2Mo2O7, which is free of quenched disorder, can exhibit a
+simultaneous glass transition, working as dynamical randomness to each other.
+The interplay of spins and orbitals is mediated by the Jahn-Teller lattice
+distortion that selects the choice of orbitals, which then generates variant
+spin exchange interactions ranging from ferromagnetic to antiferromagnetic
+ones. Our Monte Carlo simulations detect the power-law divergence of the
+relaxation times and the negative divergence of both the magnetic and
+dielectric non-linear susceptibilities, resolving the long-standing puzzle on
+the origin of the disorder-free spin glass.",1908.05070v3
+2019-08-16,Metallic liquid H3O in a thin-shell zone inside Uranus and Neptune,"The Solar System harbors deep unresolved mysteries despite centuries-long
+study. A highly intriguing case concerns anomalous non-dipolar and
+non-axisymmetric magnetic fields of Uranus and Neptune that have long eluded
+explanation by the prevailing theory. A thin-shell dynamo conjecture captures
+observed phenomena but leaves unexplained fundamental material basis and
+underlying mechanism. Here, we report the discovery of trihydrogen oxide (H3O)
+in metallic liquid state stabilized at extreme pressure and temperature
+conditions inside these icy planets. Calculated stability pressure field
+compared to known pressure-radius relation for Uranus and Neptune places
+metallic liquid H3O in a thin-shell zone near planetary cores. These findings
+from accurate quantum mechanical calculations rationalize the empirically
+conjectured thin-shell dynamo model and establish key physical benchmarks that
+are essential to elucidating the enigmatic magnetic-field anomaly of Uranus and
+Neptune, resolving a major mystery in planetary science.",1908.05821v1
+2019-08-18,Conductivity noise across temperature driven transitions of rare-earth nickelate heterostructures,"The metal-insulator transition (MIT) of bulk rare-earth nickelates is
+accompanied by a simultaneous charge ordering (CO) transition. We have
+investigated low-frequency resistance fluctuations (noise) across the MIT and
+magnetic transition of [EuNiO$_3$/LaNiO$_3$] superlattices, where selective
+suppression of charge ordering has been achieved by mismatching the
+superlattice periodicity with the periodicity of charge ordering. We have
+observed that irrespective of the presence/absence of long-range CO, the noise
+magnitude is enhanced by several orders with strong non-1/$f$ ($f$ = frequency)
+component when the system undergoes MIT and magnetic transition. The higher
+order statistics of resistance fluctuations reveal the presence of strong
+non-Gaussian components in both cases, further indicating inhomogeneous
+electrical transport arising from the electronic phase separation.
+Specifically, we find almost three orders of magnitude smaller noise in the
+insulating phase of the sample without long-range CO compared to the sample
+with CO. These findings suggest that digital synthesis can be a potential route
+to implement electronic transitions of complex oxides for device application.",1908.06413v1
+2019-08-28,A Cantilever Torque Magnetometry Method for the Measurement of Hall Conductivity of Highly Resistive Samples,"We present the first measurements of Hall conductivity utilizing a new torque
+magnetometry method designed for insulators. A Corbino disk exhibits a magnetic
+dipole moment proportional to Hall conductivity when voltage is applied across
+a test material. This magnetic dipole moment can be measured through torque
+magnetometry. The symmetry of this contactless technique allows for the
+measurement of Hall conductivity in previously inaccessible materials. Finally,
+a low-temperature noise bound, the lack of systematic errors on dummy devices,
+and a measurement of the Hall conductivity of sputtered indium tin oxide
+demonstrate the efficacy of the technique.",1908.10857v3
+2019-12-01,Coarse-graining in micromagnetic simulations of dynamic hysteresis loops,"Micromagnetic simulations based on the stochastic Landau-Lifshitz-Gilbert
+equation are used to calculate dynamic magnetic hysteresis loops relevant to
+magnetic hyperthermia. With the goal to effectively simulate room-temperature
+loops for large iron-oxide-based systems at relatively slow sweep rates on the
+order of 1 Oe/ns or less, a previously derived renormalization group approach
+for coarse-graining (Grinstein and Koch, Phys. Rev. Lett. 20, 207201, 2003) is
+modified and applied to calculating loops for a magnetite nanorod. The nanorod
+modelled is the building block for larger nanoparticles that were employed in
+preclinical studies (Dennis et al., Nanotechnology 20, 395103, 2009). The
+scaling algorithm is shown to produce nearly identical loops over several
+decades in the model grain size. Sweep-rate scaling involving the Gilbert
+damping parameter is also demonstrated to allow orders of magnitude speed-up of
+the loop calculations.",1912.00310v3
+2020-02-29,Nonreciprocal Emergence of Hybridized Magnons in magnetic thin Films,"We investigate the transfer and control of nonreciprocity through magnons
+themselves in permalloy thin films deposited on surface oxide silicon
+substrate. Evidences of nonreciprocal emergence of hybridized dipole exchange
+magnons (spin waves) at two permalloy surfaces are provided by studying magnon
+transmission and asymmetry, via Brillouin light scattering measurements. The
+dipole dominated spin wave and exchange dominated spin wave are found to be
+localized near the top and bottom surfaces, respectively, and traveling along
+opposite directions. The nonreciprocity and the localization are intertwined
+and ca n be tuned by an in plane magnetic field. The effects are well explained
+by the magnetostatic theory and can be quantitatively reproduced by the
+micromagnetic simulations. Our findings provide a simple and flexible approach
+to nonreciprocal all magnon logi c devices with highly compatible with silicon
+based integrated circuit technology.",2003.00230v4
+2020-03-20,Spin-orbit-coupled metal candidate PbRe2O6,"We study the lead rhenium oxide PbRe2O6 as a candidate spin-orbit-coupled
+metal (SOCM), which has attracted much attention as a testing ground for
+studying unconventional Fermi liquid instability associated with a large
+spin-orbit interaction. The compound comprises a stack of modulated honeycomb
+lattices made of Re5+ (5d2) ions in a centrosymmetric R-3m structure at room
+temperature. Resistivity, magnetic susceptibility, and heat capacity
+measurements using single crystals reveal two successive first-order phase
+transitions at Ts1 = 265 K and Ts2 = 123 K. At Ts1, the magnetic susceptibility
+is enormously reduced and a structural transition to a monoclinic structure
+takes place, while relatively small changes are observed at Ts2. Surprisingly,
+PbRe2O6 bears a close resemblance to another SOCM candidate Cd2Re2O7 despite
+crucial differences in the crystal structure and probably in the electronic
+structure, suggesting that PbRe2O6 is an SOCM.",2003.09051v1
+2020-08-05,Spin filtering in germanium/silicon core/shell nanowires with pseudo-helical gap,"Semiconductors with strong spin-orbit interactions can exhibit a helical gap
+with spin-momentum locking opened by a magnetic field. Such a gap is highly
+spin selective as a result of a topologically protected spin-momentum locking,
+which can be used for spin filtering. We experimentally demonstrate such a spin
+filtering effect in a quasi-ballistic p-type germanium/silicon core/shell
+nanowire (NW), which possesses a pseudo-helical gap without the application of
+magnetic field. Polarized hole spin injection to the NW is achieved using
+cobalt ferromagnetic contacts with controlled natural surface oxide on the NW
+as a tunnel barrier. Local and nonlocal spin valve effects are measured as the
+verification of polarized spin transport in the NW outside the helical gap. We
+electrically tune the NW into the helical gap by scanning its chemical
+potential with a gate. A hysteresis loop with three resistance states is
+observed in the local spin valve geometry, as an evidence of spin filtering in
+the helical gap.",2008.01952v1
+2020-08-18,Near-Zero-Field Spin-Dependent Recombination Current and Electrically Detected Magnetic Resonance from the Si/SiO$_2$ interface,"Dielectric interfaces critical for metal-oxide-semiconductor (MOS) electronic
+devices, such as the Si/SiO$_2$ MOS field effect transistor (MOSFET), possess
+trap states that can be visualized with electrically-detected spin resonance
+techniques, however the interpretation of such measurements has been hampered
+by the lack of a general theory of the phenomena. This article presents such a
+theory for two electrical spin-resonance techniques, electrically detected
+magnetic resonance (EDMR) and the recently observed near-zero field
+magnetoresistance (NZFMR), by generalizing Shockley Read Hall trap-assisted
+recombination current calculations via stochastic Liouville equations. Spin
+mixing at this dielectric interface occurs via the hyperfine interaction, which
+we show can be treated either quantum mechanically or semiclassically, yielding
+distinctive differences in the current across the interface. By analyzing the
+bias dependence of NZFMR and EDMR, we find that the recombination in a
+Si/SiO$_2$ MOSFET is well understood within a semiclassical approach.",2008.08121v1
+2020-08-28,Novel Copper Fluoride Analogs of Cuprates,"On the basis of the first-principles evolutionary crystal structure
+prediction of stable compounds in the Cu-F system, we predict two
+experimentally unknown stable phases -- Cu2F5 and CuF3. Cu2F5 comprises two
+interacting magnetic subsystems with the Cu atoms in the oxidation states +2
+and +3. CuF3 contains magnetic Cu 3+ ions forming a lattice with the
+antiferromagnetic coupling. We showed that some or all of Cu 3+ ions can be
+reduced to Cu 2+ by electron doping, as in the well known KCuF3. Significant
+similarities between the electronic structures calculated in the framework of
+DFT+U suggest that doped CuF3 and Cu2F5 may exhibit high-temperature
+superconductivity with the same mechanism as in cuprates.",2008.12491v1
+2020-10-21,Interface combinatorial pulsed laser deposition to enhance heterostructures functional properties,"In this chapter we will describe a new development of combinatorial pulsed
+laser deposition (CPLD) which targets the exploration of interface libraries.
+The idea is to modulate continuously the composition of interfaces on a few
+atomic layers in order to alter their functional properties. This unique
+combinatorial synthesis of interfaces is possible due to very specific PLD
+characteristics. The first one is its well-known ability for complex oxide
+stoichiometry transfer from the target to the film. The second one is the layer
+by layer control of thin film growth at the atomic level using in-situ RHEED
+characterization. The third one relates to the directionality of the ablated
+plume which allows for selective area deposition on the substrate using a
+mobile shadow-mask. However PLD also has some limitations and important PLD
+aspects to be considered for reliable CPLD are reviewed. Multiple examples
+regarding the control of interface magnetism in magnetic tunnel junctions and
+energy band and Schottky barrier height tuning in ferroelectric tunable
+capacitors are presented.",2010.10773v2
+2020-10-27,"Predicting the Structural, Electronic and Magnetic Properties of Few Atomic-layer Polar Perovskite","Density functional theory (DFT) calculations are performed to predict the
+structural, electronic and magnetic properties of electrically neutral or
+charged few-atomic-layer (AL) oxides whose parent systems are based on polar
+perovskite $KTaO_{3}$. Their properties vary greatly with the number of ALs
+($n_{AL}$) and the stoichiometric ratio. In the few-AL limit ($n_{AL}\leqslant
+14$), the even AL (EL) systems with chemical formula $(KTaO_{3})_{n}$ are
+semiconductors, while the odd AL (OL) systems with formula
+($K_{n+1}Ta_{n}O_{3n+1}$ or $K_{n}Ta_{n+1}O_{3n+2}$) are half-metal except for
+the unique $KTa_{2}O_{5}$ case which is a semiconductor due to the large
+Peierls distortions. After reaching certain critical thickness ($n_{AL}>14$),
+the EL systems show ferromagnetic surface states, while ferromagnetism
+disappears in the OL systems. These predictions from fundamental complexity of
+polar perovskite when approaching the two-dimensional (2D) limit may be helpful
+for interpreting experimental observations later.",2010.13977v1
+2020-10-28,Complete phase diagram of Sr$_{1-x}$La$_x$FeO$_3$ with versatile magnetic and charge ordering,"A detailed electronic phase diagram of perovskite-type oxides
+Sr$_{1-x}$La$_x$FeO$_3$ $(0\leq x \leq 0.5)$ was established by synchrotron
+X-ray diffraction, magnetization, and transport measurements for
+polycrystalline samples synthesized by a high-pressure technique. Among three
+kinds of helimagnetic phases in SrFeO$_3$ at zero field, two of them showing
+multiple-${\it q}$ helimagnetic spin textures tend to rapidly disappear in
+cubic symmetry upon the La substitution with $x$ less than 0.1, which
+accompanies the loss of metallic nature. On the other hand, the third
+helimagnetic phase apparently remains robustly in Sr$_{1-x}$La$_x$FeO$_3$ with
+$x$ higher than 0.1, followed by merging to the spin/charge ordered phase with
+$x\sim 1/3$. We propose an important role of itinerant ligand holes on the
+emergence of multiple-${\it q}$ states and a possible link between the third
+(putative single-${\it q}$) helimagnetic phase in SrFeO$_3$ and the spin/charge
+ordered phase in Sr$_{2/3}$La$_{1/3}$FeO$_3$.",2010.14966v1
+2020-11-06,Template-Free Preparation of Thermoresponsive Mag-netic Cilia Compatible with Biological Conditions,"Bio-inspired materials are commonly used in the development of functional
+devices. The fabrication of artificial cilia mimicking the biological functions
+has emerged as a promising strategy for fluid manipulation in miniaturized
+systems. In this study, we propose a different physicochemical insight for the
+preparation of magnetic cilia based on the temperature-triggered reversible
+assembly of coated iron oxide nanoparticles in a bio-compatible template-free
+approach. The length of the prepared cilia could be tuned between 10 and 100
+microns reaching aspect ratios up to 100 in a very dense array of flexible
+structures with persistence lengths around 8 microns. Magnetic actuation of the
+cilia revealed robust structures (over several hours of actuation) with a wide
+range of bending amplitudes resulting from high susceptibility of the
+filaments. The results demonstrate that the proposed strategy is an efficient
+and versatile alternative for templated fabrication methods and producing cilia
+with remarkable characteristics and dimensions within the template-free
+approaches.",2011.03347v1
+2020-11-14,Fabrication Of Economical Signal Amplified Vibrating Sample Magnetometer With Spiral Designed Detector,"The design and fabrication of a cost-effective vibrating sample magnetometer
+are explained. Improvement in the detected signal can be obtained using an
+operational amplifier circuit. The fabricated spiral detection coil design
+enhances the induced voltage obtained as shielding flux is reduced. A homemade
+setup is obtained by taking a woofer as an actuator and plexiglass as the
+vibrating medium. Lock-in amplifier analyzed the booster enhanced induced
+voltage signal by the principle of phase detection. Study of amplified and non
+amplified signals from the Nickel (99% purity) sample was done. Conversion of
+induced voltage to magnetization was done by calibration incorporating the
+coercivity and retentivity measurement. Magnetic oxide can be analyzed using
+this cost-effective designed Vibrating sample magnetometer. The data obtained
+from the VSM can conclude the successful operation of the designed
+magnetometer.",2011.07253v1
+2020-11-16,"First-principles study of the electronic, magnetic, and crystal structure of perovskite molybdates","The molybdate oxides SrMoO$_3$, PbMoO$_3$, and LaMoO$_3$ are a class of
+metallic perovskites that exhibit interesting properties including high
+mobility, and unusual resistivity behavior. We use first-principles methods
+based on density functional theory to explore the electronic, crystal, and
+magnetic structure of these materials. In order to account for the electron
+correlations in the partially-filled Mo $4d$ shell, a local Hubbard $U$
+interaction is included. The value of $U$ is estimated via the constrained
+random-phase approximation approach, and the dependence of the results on the
+choice of $U$ are explored. For all materials, GGA+$U$ predicts a metal with an
+orthorhombic, antiferromagnetic structure. For LaMoO$_3$, the $Pnma$ space
+group is the most stable, while for SrMoO$_3$ and PbMoO$_3$, the $Imma$ and
+$Pnma$ structures are close in energy. The $R_4^+$ octahedral rotations for
+SrMoO$_3$ and PbMoO$_3$ are found to be overestimated compared to the
+experimental low-temperature structure.",2011.08323v2
+2020-11-24,Uniaxial Néel Vector Control in Perovskite Oxide Thin Films by Anisotropic Strain Engineering,"Antiferromagnetic thin films typically exhibit a multi-domain state, and
+control of the antiferromagnetic N\'eel vector is challenging as
+antiferromagnetic materials are robust to magnetic perturbations. By relying on
+anisotropic in-plane strain engineering of epitaxial thin films of the
+prototypical antiferromagnetic material LaFeO3, uniaxial N\'eel vector control
+is demonstrated. Orthorhombic (011)- and (101)-oriented DyScO3, GdScO3 and
+NdGaO3 substrates are used to engineer different anisotropic in-plane strain
+states. The anisotropic in-plane strain stabilises structurally monodomain
+monoclinic LaFeO3 thin films. The uniaxial N\'eel vector is found along the
+tensile strained b axis, contrary to bulk LaFeO3 having the N\'eel vector along
+the shorter a axis, and no magnetic domains are found. Hence, anisotropic
+strain engineering is a viable tool for designing unique functional responses,
+further enabling antiferromagnetic materials for mesoscopic device technology.",2011.12056v1
+2020-11-27,Understanding doping of quantum materials,"Doping mobile carriers into ordinary semiconductors such as Si, GaAs, and ZnO
+was the enabling step in the electronic and optoelectronic revolutions. The
+recent emergence of a class of ""Quantum Materials"", where uniquely quantum
+interactions between the components produce specific behaviors such as
+topological insulation, unusual magnetism, superconductivity,
+spin-orbit-induced and magnetically-induced spin splitting, polaron formation,
+and transparency of electrical conductors, pointed attention to a range of
+doping-related phenomena associated with chemical classes that differ from the
+traditional semiconductors. These include wide-gap oxides, compounds containing
+open-shell d electrons, and compounds made of heavy elements yet having
+significant band gaps. The atomistic electronic structure theory of doping that
+has been developed over the past two decades in the sub-field of semiconductor
+physics has recently been extended and applied to quantum materials. The
+present review focuses on explaining the main concepts needed for a basic
+understanding of the doping phenomenology and indeed peculiarities in quantum
+materials from the perspective of condensed matter theory, with the hope of
+forging bridges to the chemists that have enabled the synthesis of some of the
+most interesting compounds in this field.",2011.13521v1
+2020-11-27,d0 Ferromagnetism in Ag-doped Monoclinic ZrO2 Compounds,"Recently d0 or intrinsic ferromagnetism was believed to provide an
+alternative pathway to transition metal induced ferromagnetism in oxide. In
+pursuit of augmenting the area of d0 ferromagnetism; we have undertaken to
+study the crystal structure and magnetic properties of Ag-doped ZrO2 compounds.
+Polycrystalline samples of Zr1-xAgxO2 (with x=0, 0.02, 0.04, 0.06 and 0.08)
+were prepared by solid-state reaction route. All the prepared compounds are
+found to crystallize in monoclinic symmetry of ZrO2. In our study, pure ZrO2
+compound exhibits paramagnetic behavior. However, the Ag-doped ZrO2 compounds
+exhibit ferromagnetic to paramagnetic transition. The Curie temperature was
+found to increase from 28.7 K for x=0.02 to 173.2 K for x= 0.08 doped ZrO2.
+Thus, the introduction of Ag in ZrO2 induces ferromagnetism with a large
+ThetaC. The measurements of hysteresis curves indicate that Ag doped ZrO2
+compounds exhibit hysteresis loops with a coercivity of around 1350 Oe.
+Moreover, increase in Ag concentration resulted increase in the value of
+saturation magnetization (MS); the maximum value of MS was recorded as 0.01
+{\mu}B/Ag ion for x= 0.06 sample. The sintering of sample at high temperature
+(13500C) diminishes the ferromagnetism and it leads to paramagnetic behaviour.",2011.13727v1
+2021-03-10,Crystal Growth of a New 8H Perovskite Sr8Os6.3O24 Exhibiting High TC Ferromagnetism,"Single crystals of a new twinned hexagonal perovskite compound Sr8Os6.3O24
+have been synthesized, and structural and magnetic properties have been
+determined. The compound crystallizes in a hexagonal cell with lattice
+parameters a = 9.6988(3) {\AA} and c = 18.1657(5) {\AA}. The structure is an
+eight-layered hexagonal B-site deficient perovskite with the layer sequence
+(ccch)2 and represents the first example of a hexagonal structure among 5d
+oxides adopting a twin option. The sample shows spontaneous ferromagnetic
+magnetization below 430 K with a small saturation moment of 0.11 {\mu}B/Os ion.
+This is the highest Curie temperature (TC) reported for any bulk perovskite
+containing only 5d ions at the B site.",2103.06305v1
+2021-05-21,Photo-induced Antiferromagnetic-ferromagnetic Transition and Electronic Structure Modulation in GdBaCo$_2$O$_{5.5}$ Thin Film,"We investigate both the ferromagnetic (FM) and antiferromagnetic (AFM)
+ultrafast dynamics of a strongly correlated oxide system, GdBaCo$_2$O$_{5.5}$
+thin film, by time-resolved x-ray magnetic circular dichroism in reflectivity
+(XMCDR) and resonant magnetic x-ray diffraction (RMXD). A photo-induced AFM-FM
+transition characterized by an increase of the transient XMCDR beyond the
+unpumped value and a decay of RMXD was observed. The photon-energy dependence
+of the transient XMCDR and reflectivity can likely be interpreted as a
+concomitant photo-induced spinstate transition.",2105.10083v1
+2021-06-18,Abrupt orthorhombic relaxation in compressively strained ultra-thin SrRuO3 films,"Lattice structure can dictate electronic and magnetic properties of a
+material. Especially, reconstruction at a surface or heterointerface can create
+properties that are fundamentally different from those of the corresponding
+bulk material. We have investigated the lattice structure on the surface and in
+the thin films of epitaxial SrRuO3 with the film thickness up to 22
+pseudo-cubic unit cells (u.c.), using the combination of surface sensitive low
+energy electron diffraction and bulk sensitive scanning transmission electron
+microscopy. Our analysis indicates that, in contrast to many perovskite oxides,
+the RuO6 tilt and rotational distortions appear even in single unit cell SrRuO3
+thin films on cubic SrTiO3, while the full relaxation to the bulk-like
+orthorhombic structure takes 3-4 u.c. from the interface for thicker films. Yet
+the TiO6 octahedra of the substrate near the interface with SrRuO3 films show
+no sign of distortion, unlike those near the interface with CaRuO3 films. Two
+orthogonal in-plane rotated structural domains are identified. These structural
+distortions are essential for the nature of the thickness dependent transport
+and magnetism in ultrathin films.",2106.10204v1
+2021-07-05,Collective spin and charge excitations in the $t$-$J$-$U$ model of high-$T_c$ cuprates,"The $t$-$J$-$U$ model of high-$T_c$ copper-oxide superconductors incorporates
+both the on-site Coulomb repulsion and kinetic exchange interaction and yields
+a semi-quantitative description of the static properties of those materials. We
+extend this analysis to dynamic quantities and address collective spin- and
+charge excitations in the correlated metallic state of the $t$-$J$-$U$ model.
+We employ VWF+$1/\mathcal{N}_f$ approach that combines the variational wave
+function (VWF) approach with the expansion in the inverse number of fermionic
+flavors ($1/\mathcal{N}_f$). It is shown that the resonant (paramagnon)
+contribution to the dynamic magnetic susceptibility remains robust as one
+interpolates between the Hubbard- and $t$-$J$-model limits, whereas the
+incoherent continuum undergoes substantial renormalization. Energy of the
+collective charge mode diminishes as the strong-coupling limit is approached.
+We also introduce the concept of effective kinetic exchange interaction that
+allows for a unified interpretation of magnetic dynamics in the Hubbard,
+$t$-$J$, and $t$-$J$-$U$ models. The results are discussed in the context of
+recent resonant inelastic $x$-ray scattering experiments for the high-$T_c$
+cuprates.",2107.02152v1
+2021-07-26,Engineering of Ferroic Orders in Thin Films by Anionic Substitution,"Multiferroics are a unique class of materials where magnetic and
+ferroelectric orders coexist. The research on multiferroics contributes
+significantly to the fundamental understanding of the strong correlations
+between different material degrees of freedom and provides an energy-efficient
+route toward the electrical control of magnetism. While multiple ABO3 oxide
+perovskites have been identified as being multiferroic, their magnetoelectric
+coupling strength is often weak, necessitating the material search in different
+compounds. Here, we report the observation of room-temperature multiferroic
+orders in multi-anion SrNbO3-xNx thin films. In these samples, the multi-anion
+state enables the room-temperature ferromagnetic ordering of the Nb
+d-electrons. Simultaneously, we find ferroelectric responses that originate
+from the structural symmetry breaking associated with both the off-center
+displacements of Nb and the geometric displacements of Sr, depending on the
+relative O-N arrangements within the Nb-centered octahedra. Our findings not
+only diversify the available multiferroic material pool but also demonstrate a
+new multiferroism design strategy via multi-anion engineering.",2107.12509v1
+2021-08-07,Space-based weather observatory at Earth-Moon Lagrange point L1 to monitor earth's magnetotail effects on the Moon,"Lunar hematite is formed by the oxidation of iron on the surface of the Moon
+by oxygen from the Earth's upper atmosphere. The Moon's surface is continuously
+affected by solar particles from the sun. However, Earth's magnetic tail blocks
+99 % of the solar wind and provides windows of opportunity to transport oxygen
+from Earth's upper atmosphere to the Moon through magnetotail when it is in its
+full moon phase. Here, we propose to place a space weather observatory at the
+Earth-Moon L1 Lagrange point carrying a crucial payload onboard to study how
+Earth's magnetotail causes the Moon's surface to rust. The space weather
+observatory monitors the effect of Earth's magnetic field on the Moon using
+advanced spectroscopic sensors from Lagrange-based stations. Earth-moon L1
+Lagrange point is the key location for space-weather observation as spacecraft
+near this point obtains a nearly unobstructed view of the moon. Numerical
+methods needed for a high-order analytical approximation have been implemented
+for more accurate predictions.",2108.03522v2
+2021-10-25,Large Phonon Thermal Hall Conductivity in a Simple Antiferromagnetic Insulator,"Phonons are known to generate a thermal Hall effect in certain insulators,
+including oxides with rare-earth impurities, quantum paraelectrics,
+multiferroic materials and cuprate Mott insulators. In each case, a special
+feature of the material is presumed relevant for the underlying mechanism that
+confers chirality to phonons in a magnetic field. The question is whether a
+phonon Hall effect is an unusual occurrence - linked to special characteristics
+such as skew scattering off rare-earth impurities, structural domains,
+ferroelectricity, ferromagnetism - or a much more common property of insulators
+than hitherto believed. To help answer this question, we have turned to a
+simple insulator, with none of the previously encountered special features: the
+cubic antiferromagnet Cu$_3$TeO$_6$. We find that it has the largest thermal
+Hall conductivity $\kappa_{\rm{xy}}$ of any insulator so far. We show that this
+record-high $\kappa_{\rm{xy}}$ signal is due to phonons and it does not require
+the presence of magnetic order, as it persists above the ordering temperature.
+We conclude that the phonon Hall effect is likely to be a fairly common
+property of solids.",2110.13277v1
+2021-10-30,"Excitonic Correlations, Spin-State Ordering, and Magnetic-Field Effects in One-Dimensional Two-Orbital Hubbard Model for Spin-Crossover Region","The electronic properties of excitonic insulators have been examined
+precisely in recent years. Pictures of exciton condensation may be applied to
+the spin-state transition observed in perovskite cobalt oxides. We examine the
+crystal-field and magnetic-field dependences of spatial spin structures on the
+basis of the density matrix renormalization group method using an effective
+model for the one-dimensional two-orbital Hubbard model in strong-coupling
+limit. We find an excitonic insulating (EI) phase and a spin-state ordering
+(SSO) phase in the intermediate region between low-spin and high-spin phases.
+In the EI phase, spin-triplet excitons are spatially fluctuating due to quantum
+effects, and an incommensurate spin correlation realizes. The analyses of a
+spin gap and degeneracy of entanglement spectra suggest the realization of the
+Haldane-like edge state in the EI phase. In the SSO phase, 3-fold or
+incommensurate SSO structures realize depending on the crystal-field splitting.
+These structures are stabilized as a result of the competition of exchange
+interactions between spin states.",2111.00209v4
+2021-12-09,Tuneable electron-magnon coupling of ferromagnetic surface states in PdCoO$_2$,"Controlling spin wave excitations in magnetic materials underpins the
+burgeoning field of magnonics. Yet, little is known about how magnons interact
+with the conduction electrons of itinerant magnets, or how this interplay can
+be controlled. Via a surface-sensitive spectroscopic approach, we demonstrate a
+strong and highly-tuneable electron-magnon coupling at the Pd-terminated
+surface of the delafossite oxide PdCoO$_2$, where a polar surface charge
+mediates a Stoner transition to itinerant surface ferromagnetism. We show how
+the coupling can be enhanced 7-fold with increasing surface disorder, and
+concomitant charge carrier doping, becoming sufficiently strong to drive the
+system into a polaronic regime, accompanied by a significant quasiparticle mass
+enhancement. Our study thus sheds new light on electron-magnon interactions in
+solid-state materials, and the ways in which these can be controlled.",2112.04869v1
+2022-01-11,Giant Valley-Polarized Spin Splittings in Magnetized Janus Pt Dichalcogenides,"We reveal giant proximity-induced magnetism and valley-polarization effects
+in Janus Pt dichalcogenides (such as SPtSe), when bound to the Europium oxide
+(EuO) substrate. Using first-principles simulations, it is surprisingly found
+that the charge redistribution, resulting from proximity with EuO, leads to the
+formation of two K and K$^{'}$valleys in the conduction bands. Each of these
+valleys displays its own spin polarization and a specific spin-texture dictated
+by broken inversion and time-reversal symmetries, and valley-exchange and
+Rashba splittings as large as hundreds of meV. This provides a platform for
+exploring novel spin-valley physics in low-dimensional semiconductors, with
+potential spin transport mechanisms such as spin-orbit torques much more
+resilient to disorder and temperature effects.",2201.04106v1
+2022-01-18,"Characterization of the Magnetism and Conformation of Single Porphyrin Molecules Adsorbed on Surfaces, and Artificial Graphene Nanoflakes","My thesis mostly focusses on the systems of porphyrin molecules adsorbed on
+single-crystalline metallic surfaces. Cyclic tetrapyrrole porphyrins play key
+roles in many important chemical and biological processes, such as oxygen
+transport in heme (iron porphyrin), electron transfer and oxidation reactions
+in photosynthetic chlorophyll (magnesium porphyrin). Comprehensive
+understanding of the magnetic and conformational properties of single porphyrin
+molecules adsorbed on metallic substrates attracts intensive research interest.
+In my thesis, I have studied the structural and electronics properties of
+porphyrin molecules by Low-temperature scanning tunneling spectroscopy (LT-STM)
+and scanning tunneling spectroscopy (STS) and theoretical methods. Owing to the
+high resolution of LT-STM, both geometric and electronic properties at the
+atomic level were probed. Moreover, the experimental results were understood by
+comprehensive theoretical methods, i.e. density functional theory, molecular
+dynamics, tight-binding and plane-wave expansion calculations.",2201.07085v2
+2022-01-21,Electron Spin Resonance Scanning Tunneling Microscope of Non-Magnetic Molecules,"Electron Spin Resonance-Scanning Tunneling Microscopy (ESR-STM) of C60
+radical ion on graphene is a first demonstration on radical ions. ESR-STM
+signal at g=2.00 was measured in accordance with macroscopic ESR of fullerene
+radical ion. The ESR-STM signal was bias voltage dependent, as it reflects the
+charge state of the molecule. The signal appears in the bias voltage which
+enables the ionization of the lowest unoccupied molecular orbital (LUMO)
+(creation of radical anion) and the highest occupied molecular orbital (HOMO
+(creation of a radical cation) of the C60 molecule when it deposited on
+graphene.
+  The linewidth provides information on the lifetime of the free radical. In
+several experiments, a 13C hyperfine splitting was observed, and a change in
+the phase of the ESR-STM peak as a function of the speed of the magnetic field
+sweep was changed. This might be used to provide information on the relaxation
+times of the molecules. In parallel, ESR-STM signal at g=1.6 was ascribed to
+Tungsten oxide (W5+) at the tip apex, which is not bias voltage dependent.
+  The ability of ESR-STM to explore non paramagnetic molecules, significantly
+broadens the scope of this technique.",2201.08608v1
+2022-01-31,Nuclear spin-lattice relaxation studies of Cu$_{2}$O,"We report the $^{63}$Cu and $^{65}$Cu nuclear spin-lattice relaxation rate
+measurements of cuprous oxide Cu$_2$O in a zero field Cu nuclear quadrupole
+resonance at $T$ = 77$-$325 K. From the detailed isotopic measurements of the
+relaxation rates, we successfully estimated a finite magnetic relaxation rate
+$^{63}W_M$ and a predominant nuclear quadrupole relaxation rate $^{63}W_Q$.
+$^{63}W_Q$ changed as $T^{2.1}$, while $^{63}W_M$ changed as $T^{1.6}$ or
+$T^{\beta}\mathrm{exp}(-\it\Delta/T)$ with $\beta$ = 0.6(3) and $\it\Delta$ =
+190(62) K. The nuclear spin scattering process due to a non-degenerate Fermi
+gas was discussed as a possible candidate of the magnetic relaxation.",2201.13074v3
+2022-05-02,Suppression of Motion Artifacts Caused by Temporally Recurring Tracer Distributions in Multi-Patch Magnetic Particle Imaging,"Magnetic particle imaging is a tracer based imaging technique to determine
+the spatial distribution of superparamagnetic iron oxide nanoparticles with a
+high spatial and temporal resolution. Due to physiological constraints, the
+imaging volume is restricted in size and larger volumes are covered by shifting
+object and imaging volume relative to each other. This results in reduced
+temporal resolution, which can lead to motion artifacts when imaging dynamic
+tracer distributions. A common source of such dynamic distributions are cardiac
+and respiratory motion in in-vivo experiments, which are in good approximation
+periodic. We present a raw data processing technique that combines data
+snippets into virtual frames corresponding to a specific state of the dynamic
+motion. The technique is evaluated on the basis of measurement data obtained
+from a rotational phantom at two different rotational frequencies. These
+frequencies are determined from the raw data without reconstruction and without
+an additional navigator signal. The reconstructed images give reasonable
+representations of the rotational phantom frozen in several different states of
+motion while motion artifacts are suppressed.",2205.01085v1
+2022-07-15,Tunable spin and orbital Edelstein effect at (111) LaAlO$_3$/SrTiO$_3$ interface,"Converting charge current into spin current is one of the main mechanisms
+exploited in spintronics. One prominent example is the Edelstein effect, namely
+the generation of a magnetization in response to an external electric field,
+which can be realized in systems with lack of inversion symmetry. If a system
+has electrons with an orbital angular momentum character, an orbital
+magnetization can be generated by the applied electric field giving rise to the
+so-called orbital Edelstein effect. Oxide heterostructures are the ideal
+platform for these effects due to the strong spin-orbit coupling and the lack
+of inversion symmetries. Beyond a gate-tunable spin Edelstein effect, we
+predict an orbital Edelstein effect an order of magnitude larger then the spin
+one at the (111) LaAlO$_3$/SrTiO$_3$ interface. We model the material as a
+bilayer of $t_{2g}$ orbitals using a tight-binding approach, while transport
+properties are obtained in the Boltzmann approach. We give an effective model
+at low filling which explains the non-trivial behaviour of the Edelstein
+response, showing that the hybridization between the electronic bands crucially
+impacts the Edelstein susceptibility.",2207.07663v1
+2022-11-25,Possible helimagnetic order in Co4+-containing perovskites Sr1-xCaxCoO3,"We systematically synthesized perovskite-type oxides Sr1-xCaxCoO3 containing
+unusually high valence Co4+ ions by a high pressure technique, and investigated
+the effect of systematic lattice change on the magnetic and electronic
+properties. As the Ca content x exceeds about 0.6, the structure changes from
+cubic to orthorhombic, which is supported by the first-principles calculations
+of enthalpy. Upon the orthorhombic distortion, the ground state remains to be
+apparently ferromagnetic with a slight drop of the Curie temperature.
+Importantly, the compounds with x larger than 0.8 show antiferromagnetic
+behavior with positive Weiss temperatures and nonlinear magnetization curves at
+lowest temperature, implying that the ground state is noncollinear
+antiferromagnetic or helimagnetic. Considering the incoherent metallic behavior
+and the suppression of the electronic specific heat at high x region, the
+possible emergence of a helimagnetic state in Sr1-xCaxCoO3 is discussed in
+terms of the band-width narrowing and the double-exchange mechanism with the
+negative charge transfer energy as well as the spin frustration owing to the
+next-nearest neighbor interaction.",2211.13903v1
+2023-02-04,"Calculating spin-lattice interactions in ferro- and antiferromagnets: the role of symmetry, dimension and frustration","Recently, the interplay between spin and lattice degrees of freedom has
+gained a lot of attention due to its importance for various fundamental
+phenomena as well as for spintronic and magnonic applications. Examples are
+ultrafast angular momentum transfer between the spin and lattice subsystems
+during ultrafast demagnetization, frustration driven by structural distortions
+in transition metal oxides, or in acoustically driven spin-wave resonances. In
+this work, we provide a systematic analysis of spin-lattice interactions for
+ferro- and antiferromagnetic materials and focus on the role of lattice
+symmetries and dimensions, magnetic order, and the relevance of spin-lattice
+interactions for angular momentum transfer as well as magnetic frustration. For
+this purpose, we use a recently developed scheme which allows an efficient
+calculation of spin-lattice interaction tensors from first principles. In
+addition to that, we provide a more accurate and self consistent scheme to
+calculate ab initio spin lattice interactions by using embedded clusters which
+allows to benchmark the performance of the scheme introduced previously.",2302.02066v2
+2023-03-21,Inducing or suppressing the anisotropy in multilayers based on CoFeB,"Controlling the uniaxial magnetic anisotropy is of practical interest to a
+wide variety of applications. We study Co$_{40}$Fe$_{40}$B$_{20}$ single films
+grown on various crystalline orientations of LiNbO$_3$ substrates and on
+oxidized silicon. We identify the annealing conditions that are appropriate to
+induce or suppress uniaxial anisotropy. Anisotropy fields can be increased by
+annealing up to 11 mT when using substrates with anisotropic surfaces. They can
+be decreased to below 1 mT when using isotropic surfaces. In the first case,
+the observed increase of the anisotropy originates from the biaxial strain in
+the film caused by the anisotropic thermal contraction of the substrate when
+back at room temperature after strain relaxation during annealing. In the
+second case, anisotropy is progressively removed by applying successive
+orthogonal fields that are assumed to progressively suppress any chemical
+ordering within the magnetic film. The method can be applied to CoFeB/Ru/CoFeB
+synthetic antiferromagnets but the tuning of the anisotropy comes with a
+decrease of the interlayer exchange coupling and a drastic change of the
+exchange stiffness.",2303.11718v1
+2023-03-22,Role of alkaline metal in the rare-earth triangular antiferromagnet KYbO$_2$,"We report crystal structure and magnetic behavior of the triangular
+antiferromagnet KYbO$_2$, the A-site substituted version of the quantum spin
+liquid candidate NaYbO$_2$. The replacement of Na by K introduces an
+anisotropic tensile strain with 1.6% in-plane and 12.1% out-of-plane lattice
+expansion. Compared to NaYbO$_2$, both Curie-Weiss temperature and saturation
+field are reduced by about 20% as the result of the increased Yb--O--Yb angles,
+whereas the $g$-tensor of Yb$^{3+}$ becomes isotropic with $g=3.08(3)$.
+Field-dependent magnetization shows the plateau at 1/2 of the saturated value
+and suggests the formation of the up-up-up-down field-induced order in the
+triangular AYbO$_2$ oxides (A = alkali metal), in contrast to the isostructural
+selenides that exhibit the 1/3 plateau and the up-up-down field-induced order.",2303.12448v2
+2023-05-12,Control of ternary alloy composition during remote epitaxy on graphene,"Understanding the sticking coefficient $\sigma$, i.e., the probability of an
+adatom sticking to a surface, is essential for controlling the stoichiometry
+during epitaxial film growth. However, $\sigma$ on monolayer graphene-covered
+surfaces and its impact on remote epitaxy are not understood. Here, using
+molecular-beam epitaxial (MBE) growth of the magnetic shape memory alloy
+Ni$_2$MnGa, we show that the sticking coefficients for metals on
+graphene-covered MgO (001) are less than one and are temperature and element
+dependent, as revealed by ion backscattering spectrometry (IBS) and energy
+dispersive x-ray spectroscopy (EDS). This lies in stark contrast with most
+transition metals sticking on semiconductor and oxide substrates, for which
+$\sigma$ is near unity at typical growth temperatures ($T<800\degree$C). By
+initiating growth below $400 \degree$ C, where the sticking coefficients are
+closer to unity and wetting on the graphene surface is improved, we demonstrate
+epitaxy of Ni$_2$MnGa films with controlled stoichiometry that can be
+exfoliated to produce freestanding membranes. Straining these membranes tunes
+the magnetic coercive field. Our results provide a route to synthesize
+membranes with complex stoichiometries whose properties can be manipulated via
+strain.",2305.07793v1
+2023-07-24,Enhanced Magnetism and Phase Transitions in Ultrathin Quantum Spin Liquid Na2IrO3 Flakes,"The quest for quantum spin liquids has garnered significant attention due to
+their rich physics and disruptive prospects in quantum communication and
+computation. Spin-orbit coupling, electron correlation, and structural
+distortion play critical roles in the candidate materials that eventually order
+antiferromagnetically at low temperatures. We introduce quantum electron
+confinement to the existing complexity and explore the interplay between
+Heisenberg and Kitaev interactions in ultrathin \ce{Na2IrO3} layers using
+first-principles calculations. The zigzag antiferromagnetic state in the
+monolayer is reinforced and pushed further away from the Kitaev spin liquid
+state due to the increased strength of Heisenberg and off-diagonal exchange
+interactions. In contrast, the carrier-doped flakes undergo a Mott
+insulator-to-metal transition accompanied by an antiferromagnetic to
+ferromagnetic transition. These findings present exciting prospects for
+comprehending magnetism in a novel two-dimensional framework of non-van der
+Waals correlated oxide flakes.",2307.12554v1
+2023-08-18,Pressure-induced softening in bulk modulus due to magneto-elastic coupling in Nd$_2$CoFeO$_6$ double Perovskite,"Double perovskite oxide materials have garnered tremendous interest due to
+their strong spin-lattice-charge coupling. Interesting in their own right,
+rare-earth-based DPOs have yet to be subjected to high-pressure studies. In
+this paper, we have investigated the structural response of Nd$_2$CoFeO$_6$ to
+pressure by XRD and Raman spectroscopic measurements. From XRD data, we have
+observed pressure-induced structural transition from the orthorhombic phase to
+the monoclinic phase at about 13.8~\si{\giga\pascal}. An anomalous increase in
+compressibility at a much lower pressure($\sim$1.1~\si{\giga\pascal}) is seen
+where no structural transition occurs. At about the same pressure, a sudden
+drop in the slope of Raman modes is observed. Further investigation at low
+temperatures reveals that the B$_g$ Raman mode is strongly affected by magnetic
+interactions. Additional high-pressure Raman experiments with the application
+of a magnetic field indicated that the mentioned anomaly around
+1.1~\si{\giga\pascal} can be explained by a high-spin to low-spin transition of
+Co$^{3+}$.",2308.09651v2
+2023-09-21,Development of Transient $μ$SR Method for High-Flux Pulsed Muons,"In order to expand the applicability of muon spin rotation, relaxation, and
+resonance ($\mu$SR) experiments with pulsed muons and to make effective use of
+the high-flux beam, we have developed a new experimental method ``transient
+$\mu$SR''. In this method, $\mu$SR data for each muon pulse are tagged with
+external parameters such as temperature and magnetic field in real time,
+allowing the sample environment to be changed without interrupting data
+collection. As a result, continuous $\mu$SR measurements under sample
+conditions that vary on a time scale longer than the beam pulse interval (40
+ms) are realized, and efficient beam utilization is achieved by eliminating the
+lag time associated with moving between discrete measurement points. The
+transient $\mu$SR method was applied to the study of the magnetic properties of
+cupric oxide (CuO) and the observation of level-crossing resonance relaxation
+in copper, and the method was successfully established by confirming that the
+results reproduce those in the previous reports.",2309.11757v1
+2023-09-30,Quantum Materials Group Annual Report 2022,"The Quantum Materials group at Indian Institute of Technology Patna is
+working on a range of topics relating to nanoelectronics, spintronics, clean
+energy and memory design etc. The PI has past experiences of working
+extensively with superconducting systems like cuprates [1, 2], ruthanate [3],
+pnictide [4, 5], thin film heterostructures [6, 7] etc and magnetic recording
+media [8, 9] etc. In this report, we have summarised the ongoing works in our
+group. We explored a range of functional materials like two-dimensional
+materials, oxides. topological insulators, organic materials etc. using a
+combination of experimnetal and computational tools. Some of the useful
+highlights are as follows: (a) tuning and control of the magnetic and
+electronic state of 2D magentic materials with rapid enhancement in the Curie
+temperature, (b) Design and detection of single electron transistor based
+nanosensors for the detection of biological species with single molecular
+resolution, (c) Observation of non-volatile memory behaviour in the hybrid
+structures made of perovskite materials and 2D hybrids. The results offer
+useful insight in the design of nanoelectronic architecrures for diverse
+applications.",2310.00456v2
+2023-10-02,Gate-voltage switching of non-reciprocal transport in oxide-based Rashba interfaces,"The linear magnetoelectric effect (ME) is the phenomenon by which an electric
+field produces a magnetization. Its observation requires both time-reversal and
+space-inversion symmetries to be broken, as in multiferroics. While the ME
+effect has only been studied in insulating materials, it can actually exist in
+non-centrosymmetric conductors such as two-dimensional electron gases (2DEGs)
+with Rashba spin-orbit coupling. It is then coined the Edelstein effect (EE),
+by which a bias voltage -- generating a charge current -- produces a transverse
+spin density, i.e. a magnetization. Interestingly, 2D systems are sensitive to
+voltage gating, which provides an extra handle to control the EE. Here, we show
+that the sign of the EE in a SrTiO$_3$ 2DEG can be controlled by a gate
+voltage. We propose various logic devices harnessing the dual control of the
+spin density by current and gate voltages and discuss the potential of our
+findings for gate-tunable non-reciprocal electronics.",2310.01598v1
+2023-09-09,Investigation into the nature behind the interesting half levitation behavior of claimed superconductor LK-99,"A recent article published by Lee et.al. claimed to have successfully
+achieved superconductivity at room temperature (RT) has become a topical issue.
+Besides the research paper, Lee and his team provided a demonstration video of
+LK-99 half levitating (HL) on a magnet. Such interesting HL appearance has
+drawn tremendous sensation both in academia and the network. However, the true
+identity of LK-99 still remains unclear, i.e., whether the HL behavior can
+necessarily indicate the diamagnetism behavior of the sample. Here, we
+fabricated our own LK-99 samples following the procedures reported by Lee et
+al. We found quite a few sample pieces showing the typical HL that is similar
+to those reported. Meanwhile, oxidation during the sample preparation was found
+to deleterious to acquiring HL in the sample, while furnace cooling or water
+quenching in the last step revealed little effect. However, our careful
+observations indicated that those HL pieces are more likely simple
+ferromagnetic. Then we conducted a comprehensive study on the behavior patterns
+of typical diamagnetism and ferromagnetic substances interacting with a
+Nd2Fe14B magnet, and provided instructions to distinguish the characteristics
+between ferromagnetic and diamagnetic to prevent misunderstanding of LK-99 like
+levitation behavior.",2310.08594v1
+2023-10-15,A singlet-triplet hole-spin qubit in MOS silicon,"Holes in silicon quantum dots are promising for spin qubit applications due
+to the strong intrinsic spin-orbit coupling. The spin-orbit coupling produces
+complex hole-spin dynamics, providing opportunities to further optimize spin
+qubits. Here, we demonstrate a singlet-triplet qubit using hole states in a
+planar metal-oxide-semiconductor double quantum dot. We observe rapid qubit
+control with singlet-triplet oscillations up to 400 MHz. The qubit exhibits
+promising coherence, with a maximum dephasing time of 600 ns, which is enhanced
+to 1.3 us using refocusing techniques. We investigate the magnetic field
+anisotropy of the eigenstates, and determine a magnetic field orientation to
+improve the qubit initialisation fidelity. These results present a step forward
+for spin qubit technology, by implementing a high quality singlet-triplet
+hole-spin qubit in planar architecture suitable for scaling up to 2D arrays of
+coupled qubits.",2310.09722v1
+2023-12-06,Fingerprints of the Jahn-Teller and superexchange physics in optical spectra of manganites,"Transition metal oxides incorporating Jahn-Teller (JT) ions Mn3+ (3d4) in
+manganites and Cu2+ (3d9) in cuprates exhibit outstanding magnetic and
+electronic properties, including colossal magnetoresistance (CMR) and
+high-temperature superconductivity (HTSC). The physics of these compounds is
+associated with the orbitally-degenerate electronic states of JT ions, leading
+to the linear electron-lattice interaction, complemented by the entirely
+electronic superexchange (SE) interaction. Here, we discuss the fingerprints of
+the JT and SE physics in the temperature-dependent complex dielectric function
+spectra and multi-order Raman scattering spectra measured in a detwinned LaMnO3
+crystal, which is a famous compound exhibiting cooperative JT effect, being
+also a progenitor of magnetic materials exhibiting CMR effect. In accordance
+with the obtained experimental evidence, the associated effective parameters
+characterizing the JT and SE physics in manganites are presented.",2312.03677v1
+2023-12-18,Impact of Oxidation State on the Valence-bond-glass Physics in the lithium-intercalated Mo$_3$O$_8$ Cluster Mott Insulators,"We have successfully synthesized four Mo$_3$O$_8$-type cluster Mott
+insulators (CMI) by intercalating lithium into nonmagnetic precursors to
+regulate the Mo$_3$ cluster valence. The resulting materials are
+Li$_{1+x}$$R$Mo$_3$O$_8$ ($R$ = Sc, Y, Lu) and Li$_x$Zn$_2$Mo$_3$O$_8$. Our
+magnetic susceptibility measurements revealed that these materials display
+characteristics akin to a valence bond glass state and suggest the presence of
+short-range ordering when the Mo$_3$ cluster valence approximates its ideal
+value. These findings challenge the prevailing belief that the plaquette charge
+ordering state is an inherent feature of Mo$_3$O$_8$-type CMI. Instead, they
+underscore the importance of Mo$_3$ cluster valence in determining the physical
+properties of these systems. These insights furnish a fresh understanding of
+the Mo$_3$O$_8$-type CMI and open new research opportunities in highly
+frustrated magnetism.",2312.11342v1
+2024-01-02,High entropy ceramics for applications in extreme environments,"Compositionally complex materials have demonstrated extraordinary promise for
+structural robustness in extreme environments. Of these, the most commonly
+thought of are high entropy alloys, where chemical complexity grants uncommon
+combinations of hardness, ductility, and thermal resilience. In contrast to
+these metal-metal bonded systems, the addition of ionic and covalent bonding
+has led to the discovery of high entropy ceramics. These materials also possess
+outstanding structural, thermal, and chemical robustness but with a far greater
+variety of functional properties which enable access to continuously
+controllable magnetic, electronic, and optical phenomena. In this perspective,
+we outline the potential for high entropy ceramics in functional applications
+under extreme environments, where intrinsic stability may provide a new path
+toward inherently hardened device design. Current works on high entropy
+carbides, actinide bearing ceramics, and high entropy oxides are reviewed in
+the areas of radiation, high temperature, and corrosion tolerance where the
+role of local disorder is shown to create pathways toward self-healing and
+structural robustness. In this context, new strategies for creating future
+electronic, magnetic, and optical devices to be operated in harsh environments
+are outlined.",2401.01418v1
+2024-02-02,Mechanism of ferromagnetism enhancement in a La$_{2/3}$ Sr$_{1/3}$ MnO$_3$ membrane released from epitaxial strain,"Recent studies have shown that the magnetic properties of the ferromagnetic
+perovskite oxide La$_{2/3}$ Sr$_{1/3}$ MnO$_3$ (LSMO) grown on an SrTiO3 (STO)
+substrate, such as its magnetic moment and Curie temperature, can be improved
+by releasing the film from the substrate. However, the microscopic origin of
+this enhancement is not yet well understood. In this study, we use synchrotron
+radiation measurements to investigate the mechanism of ferromagnetism
+enhancement in an LSMO membrane released from an STO substrate by dissolving a
+water-soluble Sr$_4$Al$_2$O$_7$ buffer layer. Using resonant photoemission
+spectroscopy on the as-grown LSMO film and LSMO membrane, we elucidate that the
+strain release from the STO substrate enhances the itineracy of the Mn-3d
+electrons via p-d hybridization, and this strengthens the double-exchange
+interaction. The reinforcement of the double-exchange interaction, in turn,
+improves the ferromagnetism of LSMO.",2402.01179v1
+2024-02-13,Tracking topological defect motion and incommensurate charge order melting in a perovskite manganite,"Charge order pervades the phase diagrams of many quantum materials where it
+competes with superconducting and magnetic phases, hosts electronic phase
+transitions and topological defects, and couples to the lattice generating
+intricate structural distortions. Incommensurate charge order is readily
+stabilized in manganese oxides where it is associated with anomalous electronic
+and magnetic properties, but its nanoscale structural inhomogeneity complicates
+precise characterization and understanding of these phases. Leveraging
+atomic-resolution variable temperature cryogenic scanning transmission electron
+microscopy (cryo-STEM), we characterize the thermal evolution of charge order
+in a model manganite system, finding that mobile networks of topological
+defects generate phase inhomogeneity and induce incommensuration in an
+otherwise lattice-locked modulation. The melting of charge order at high
+temperatures is accompanied by generation of additional defects which decouple
+large areas of the order from the lattice.",2402.08580v1
+2024-02-22,Unraveling the origin of antiferromagnetic coupling at YIG/permalloy interface,"We investigate the structural and electronic origin of antiferromagnetic
+coupling in the Yttrium iron garnet (YIG) and permalloy (Py) bilayer system at
+the atomic level. Ferromagnetic Resonance (FMR) reveal unique hybrid modes in
+samples prepared with surface ion milling, indicative of antiferromagnetic
+exchange coupling at the YIG/Py interface. Using scanning transmission electron
+microscopy (STEM), we highlight significant interfacial differences introduced
+by ion-milling. The observations suggests that the antiferromagnetic coupling
+in YIG/Py bilayers is predominantly driven by an oxygen-mediated super-exchange
+coupling mechanism on the tetrahedral Fe terminated YIG surface, which is
+supported by density functional theory (DFT) calculations. This research
+provides critical insight into the fundamental mechanisms governing the
+efficiency of coupling in magnetic bilayers and underscores the pivotal role of
+oxide surface termination in modulating magnetic interfacial dynamics.",2402.14553v2
+2024-03-29,Synthesis of $c$-axis textured CaKFe$_4$As$_4$ superconducting bulk via spark plasma texturing technique,"Grain alignment is a key factor that determines the performance of a
+superconducting bulk. In this study, the spark plasma texturing (SPT) technique
+was used to fabricate a CaKFe$_4$As$_4$ superconducting bulk. X-ray diffraction
+and electron backscatter diffraction revealed that the $c$-axes of the
+CaKFe$_4$As$_4$ grains in the SPT bulk are aligned, demonstrating that the SPT
+technique is effective in achieving $c$-axis texture. In addition, chemical
+composition analysis showed that oxide impurities, which affect the grain
+boundary characteristics that determine the inter-grain critical current
+density ($J_c$), are randomly distributed in the SPT bulk. Magnetization
+measurements showed high $J_c$ values of the SPT bulk, reaching 127 kA
+cm$^{-2}$ and 26 kA cm$^{-2}$ at 4.2 K under a self-field and magnetic field of
+5 T, respectively. These results suggest that the SPT technique is a promising
+approach for obtaining a high-performance superconducting bulk material for
+high-field applications.",2403.19984v1
+2015-01-22,A Measure of Monopole Inertia in the Quantum Spin Ice Yb$_2$Ti$_2$O$_7$,"An important and continuing theme of modern solid state physics is the
+realization of exotic excitations in materials (e.g. quasiparticles) that have
+no analogy (or have not yet been observed) in the actual physical vacuum of
+free space. Although they are not fundamental particles, such quasiparticles do
+constitute the most basic description of the excited states of the ""vacuum"" in
+which they reside. In this regard the magnetic textures of the excited states
+of spin ices, magnetic pyrochlore oxides with dominant Ising interactions, are
+proposed to be modeled as effective magnetic charge monopoles. Recent inelastic
+neutron scattering experiments have established the pyrochlore material
+Yb$_2$Ti$_2$O$_7$ (YbTO) as a quantum spin ice, where in addition to the Ising
+interactions there are substantial transverse terms that may induce quantum
+dynamics and - in principle - coherent monopole motion. Here we report a
+combined time domain terahertz spectroscopy (TDTS) and microwave cavity study
+of YbTO to probe its complex dynamic magnetic susceptibility. We find that the
+form of the susceptibility is consistent with monopole motion and a magnetic
+monopole conductivity can be defined and measured. Using the unique phase
+sensitive capabilities of these techniques, we observe a sign change in the
+reactive part of the magnetic response. In generic models of monopole motion
+this is only possible through introducing inertial effects, e.g. a mass
+dependent term, to the equations of motion. Analogous to conventional electric
+charge systems, measurement of the conductivity's spectral weight allows us to
+derive a value for the magnetic monopole mass, which we find to be
+approximately 1800 electron masses. Our results establish the magnetic
+monopoles of quantum spin ice as true coherently propagating quasiparticles of
+this system.",1501.05638v1
+2019-05-10,Complex magnetic order in nickelate slabs,"Magnetic ordering phenomena have a profound influence on the macroscopic
+properties of correlated-electron materials, but their realistic prediction
+remains a formidable challenge. An archetypical example is the ternary nickel
+oxide system RNiO3 (R = rare earth), where the period-four magnetic order with
+proposals of collinear and non-collinear structures and the amplitude of
+magnetic moments on different Ni sublattices have been subjects of debate for
+decades. Here we introduce an elementary model system - NdNiO3 slabs embedded
+in a non-magnetic NdGaO3 matrix - and use polarized resonant x-ray scattering
+(RXS) to show that both collinear and non-collinear magnetic structures can be
+realized, depending on the slab thickness. The crossover between both spin
+structures is correctly predicted by density functional theory and can be
+qualitatively understood in a low-energy spin model. We further demonstrate
+that the amplitude ratio of magnetic moments in neighboring NiO6 octahedra can
+be accurately determined by RXS in combination with a correlated double cluster
+model. Targeted synthesis of model systems with controlled thickness and
+synergistic application of polarized RXS and ab-initio theory thus provide new
+perspectives for research on complex magnetism, in analogy to two-dimensional
+materials created by exfoliation.",1905.04160v1
+2020-12-02,Synthesis and Characterization of Sodium Iron Antimonate Na2FeSbO5 One-Dimensional Antiferromagnetic Chain Compound with a Spin Glass Ground State,"A new oxide, sodium iron antimonate, Na2FeSbO5, was synthesized and
+structurally characterized, and its static and dynamic magnetic properties were
+comprehensively studied both experimentally by dc and ac magnetic
+susceptibility, magnetization, specific heat, electron spin resonance (ESR) and
+Moessbauer measurements, and theoretically by density functional calculations.
+The resulting single-crystal structure (a = 15.6991(9) A; b = 5.3323 (4) A; c =
+10.8875(6) A; S.G. Pbna) consists of edge-shared SbO6 octahedral chains, which
+alternate with vertex-linked, magnetically active FeO4 tetrahedral chains. The
+57Fe Moessbauer spectra confirmed the presence of high-spin Fe3+ (3d5) ions in
+a distorted tetrahedral oxygen coordination. The magnetic susceptibility and
+specific heat data show the absence of a long-range magnetic ordering in
+Na2FeSbO5 down to 2 K, but ac magnetic susceptibility unambigously demonstrates
+spin-glass-type behavior with a unique two-step freezing at Tf1 about 80 K and
+Tf2 about 35 K. Magnetic hyperfine splitting of 57Fe Moessbauer spectra was
+observed below T* about 104 K (Tf1 < T*). The spectra just below T* (Tf1 < T <
+T*) exhibit a relaxation behavior caused by critical spin fluctuations,
+indicating the existence of short-range correlations. The stochastic model of
+ionic spin relaxation was used to account for the shape of the Moessbauer
+spectra below the freezing temperature. A complex slow dynamics is further
+supported by ESR data revealing two different absorption modes presumably
+related to ordered and disordered segments of spin chains. The data imply a
+spin-cluster ground state for Na2FeSbO5.",2012.01106v1
+2020-12-30,Properties of Assembly of Superparamagnetic Nanoparticles in Viscous Liquid,"Detailed calculations of the specific absorption rate (SAR) of a dilute
+assembly of iron oxide nanoparticles with effective uniaxial anisotropy
+dispersed in a liquid are performed depending on the particle diameters, the
+alternating (ac) magnetic field amplitude and the liquid viscosity. For small
+and moderate ac magnetic field amplitudes H0 with respect to particle
+anisotropy field Hk the SAR of the assembly as a function of the particle
+diameter passes through a characteristic maximum and then reaches a plateau,
+whereas for sufficiently large amplitudes, H0 ~ Hk, the SAR increases
+monotonically as a function of particle diameter. This difference is a
+consequence of realization of viscous and magnetic oscillation modes for
+particle unit magnetization vector and director for moderate and sufficiently
+large H0 values, respectively. It is found that the SAR of the assembly changes
+inversely with the viscosity only in a viscous mode, for nanoparticles of
+sufficiently large diameters. In the developed magnetic mode the SAR of the
+assembly is practically independent of the viscosity, since in this case the
+nanoparticle director only weakly oscillates around the ac magnetic field
+direction. At moderate amplitudes of the ac magnetic field the SAR values of
+the assembly in the liquid and in the solid matrix are found to be close,
+except of the range of large particle diameters and sufficiently low viscosity.
+However, at large field amplitudes the SAR of randomly oriented assembly of
+nanoparticles in a solid matrix is approximately two times less than that in a
+liquid, because a significant fraction of nanoparticles of the assembly in the
+solid matrix is not optimally oriented with respect to the ac magnetic field
+direction. The conditions for the validity of the linear response theory have
+been clarified by comparison with the numerical simulation data.",2012.15179v1
+2021-05-13,Near-Room-Temperature Ferromagnetic Behavior of Single-Atom-Thick 2D Iron in Nanolaminated Ternary MAX Phases,"Two dimensional (2D) ferromagnetic materials have attracted much attention in
+the fields of condensed matter physics and materials science, but their
+synthesis is still a challenge given their limitations on structural stability
+and susceptibility to oxidization. MAX phases nanolaminated ternary carbides or
+nitrides possess a unique crystal structure in which single-atom-thick A
+sublayers are interleaved by two dimensional MX slabs, providing nanostructured
+templates for designing 2D ferromagnetic materials if the non-magnetic A
+sublayers can be substituted replaced by magnetic elements. Here, we report
+three new ternary magnetic MAX phases (Ta2FeC, Ti2FeN and Nb2FeC) with A
+sublayers of single-atom-thick 2D iron through an isomorphous replacement
+reaction of MAX precursors (Ta2AlC, Ti2AlN and Nb2AlC) with a Lewis acid salts
+(FeCl2). All these MAX phases exhibit ferromagnetic (FM) behavior. The Curie
+temperature (Tc) of Ta2FeC and Nb2FeC MAX phase are 281 K and 291 K,
+respectively, i.e. close to room temperature. The saturation magnetization of
+these ternary magnetic MAX phases is almost two orders of magnitude higher than
+that of V2(Sn,Fe)C MAX phase whose A-site is partial substituted by Fe.
+Theoretical calculations on magnetic orderings of spin moments of Fe atoms in
+these nanolaminated magnetic MAX phases reveal that the magnetism can be mainly
+ascribed to intralayer exchange interaction of the 2D Fe atomic layers. Owning
+to the richness in composition of MAX phases, there is a large compositional
+space for constructing functional single-atom-thick 2D layers in materials
+using these nanolaminated templates.",2105.06139v1
+2022-06-17,Strain and electric field control of magnetic and electrical transport properties in a magneto-elastically coupled Fe3O4/BaTiO3(001) heterostructure,"We present a study of the control of electric field induced strain on the
+magnetic and electrical transport properties in a magneto-elastically coupled
+artificial multiferroic Fe3O4/BaTiO3 heterostructure. In this Fe3O4/BaTiO3
+heterostructure, the Fe3O4 thin film is epitaxially grown in the form of
+bilateral domains, analogous to a-c stripe domains of the underlying
+BaTiO3(001) substrate. By in-situ electric field dependent magnetization
+measurements, we demonstrate the extrinsic control of the magnetic anisotropy
+and the characteristic Verwey metal-insulator transition of the epitaxial Fe3O4
+thin film in a wide temperature range between 20-300 K, via strain mediated
+converse magnetoelectric coupling. In addition, we observe strain induced
+modulations in the magnetic and electrical transport properties of the Fe3O4
+thin film across the thermally driven intrinsic ferroelectric and structural
+phase transitions of the BaTiO3 substrate. In-situ electric field dependent
+Raman measurements reveal that the electric field does not significantly modify
+the anti-phase boundary defects in the Fe3O4 thin film once it is
+thermodynamically stable after deposition and that the modification of the
+magnetic properties is mainly caused by strain induced lattice distortions and
+magnetic anisotropy. These results provide a framework to realize electrical
+control of the magnetization in a classical highly correlated transition metal
+oxide.",2206.08664v1
+2023-03-16,Nitrogen-vacancy magnetometry of individual Fe-triazole spin crossover nanorods,"[Fe(Htrz)2(trz)](BF4) (Fe-triazole) spin crossover molecules show thermal,
+electrical, and optical switching between high spin (HS) and low spin (LS)
+states, making them promising candidates for molecular spintronics. The LS and
+HS transitions originate from the electronic configurations of Fe(II), and are
+considered to be diamagnetic and paramagnetic respectively. The Fe(II) LS state
+has six paired electrons in the ground states with no interaction with the
+magnetic field and a diamagnetic behavior is usually observed. While the bulk
+magnetic properties of Fe-triazole compounds are widely studied by standard
+magnetometry techniques their properties at the individual level are missing.
+Here we use nitrogen vacancy (NV) based magnetometry to study the magnetic
+properties of the Fe-triazole LS state of nanoparticle clusters and individual
+nanorods of size varying from 20 to 1000 nm. Scanning electron microscopy (SEM)
+and Raman spectroscopy are performed to determine the size of the
+nanoparticles/nanorods and to confirm their respective spin state. The magnetic
+field patterns produced by the nanoparticles/nanorods are imaged by NV magnetic
+microscopy as a function of applied magnetic field (up to 350 mT) and
+correlated with SEM and Raman. We found that in most of the nanorods the LS
+state is slightly paramagnetic, possibly originating from the surface oxidation
+and/or the greater Fe(III) presence along the nanorod edges. NV measurements on
+the Fe-triazole LS state nanoparticle clusters revealed both diamagnetic and
+paramagnetic behavior. Our results highlight the potential of NV quantum
+sensors to study the magnetic properties of spin crossover molecules and
+molecular magnets.",2303.09636v4
+2024-03-27,Hydroflux-Controlled Growth of Magnetic K-Cu-Te-O(H) Phases,"Innovative synthetic approaches can yield new phases containing novel
+structural and magnetic motifs. In this work, we show the synthesis and
+magnetic characterization of three new and one previously reported layered
+phase in the K-Cu-Te-O(H) phase space using a tunable hydroflux technique. The
+hydroflux, with a roughly equal molar ratio of water and alkali hydroxide, is a
+highly oxidizing, low melting solvent which can be used to isolate metastable
+phases unattainable through traditional solid state or flux techniques. The
+newly synthesized phases, K$_{2}$Cu$_{2}$TeO$_{6}$, K$_{2}$Cu$_{2}$TeO$_{6}$
+$\cdot$ H$_{2}$O, and K$_{6}$Cu$_{9}$Te$_{4}$O$_{24}$ $\cdot$ 2 H$_{2}$O,
+contain Cu$^{2+}$ within CuO$_{4}$ square planar plaquettes and TeO$_{6}$
+octahedra ordering to form structural honeycomb layers isolated by interlayer
+K$^{+}$ ions and H$_{2}$O molecules. We find the synthesized structures display
+varying tilt sequences of the CuO$_{4}$ plaquettes, leading to distinct
+Cu$^{2+}$ magnetic motifs on the structural honeycomb lattice and a range of
+effective magnetic dimensionalities. We find that K$_{2}$Cu$_{2}$TeO$_{6}$
+$\cdot$ H$_{2}$O does not order and displays alternating chain Heisenberg
+antiferromagnetic (AFM) behavior, while K$_{2}$Cu$_{2}$TeO$_{6}$ and
+K$_{6}$Cu$_{9}$Te$_{4}$O$_{24}$ $\cdot$ 2 H$_{2}$O order antiferromagnetically
+(T$_{N}$ = 100 K and T$_{N}$ = 6.5 K respectively). The previously known phase,
+K$_{2}$CuTeO$_{4}$(OH)$_{2}$ $\cdot$ H$_{2}$O, we find contains structurally
+and magnetically one-dimensional CuO$_{4}$ plaquettes leading to uniform chain
+Heisenberg AFM behavior and shows no magnetic order down to T = 0.4 K. We
+discuss and highlight the usefulness of the hydroflux technique in novel
+syntheses and the interesting magnetic motifs that arise in these particular
+phases.",2403.18726v1
+2003-06-02,Possible Spin-triplet Superconductivity in NaxCoO2yH2O - 59Co NMR Study,"We report 59Co NMR studies on the magnetically oriented powder samples of
+Co-oxide superconductors NaxCoO2yH2O with Tc ~ 4.7 K. From two-dimensional
+powder pattern in the NMR spectrum, the ab-plane Knight shift in the normal
+state was estimated by the magnetic field dependence of second-order quadrupole
+shifts at various temperatures. Below 50 K, the Knight shift shows a
+Curie-Weiss-like temperature dependence, similarly to the bulk magnetic
+susceptibility chi. From the analysis of so-called K-chi plot, the spin and the
+orbital components of K and the positive hyperfine coupling constant were
+estimated. The onset temperature of superconducting transition in the Knight
+shift does not change so much in an applied magnetic field up to 7 T, which is
+consistent with the reported high upper critical field Hc2. The Knight shift at
+7 T shows an invariant behavior below Tc. No coherence peak just below Tc was
+observed in the temperature dependence of the nuclear spin-lattice relaxation
+rate 1/T1 in both cases of NMR and NQR. We conclude that the invariant behavior
+of the Knight shift below Tc and unconventional behaviors of 1/T possibly
+indicate the spin-triplet superconductivity with p- or f-wave symmetry.",0306036v4
+2004-03-19,Quantum spin fluctuations in the dipolar Heisenberg-like rare earth pyrochlores,"The magnetic pyrochlore oxide materials of general chemical formula R2Ti2O7
+and R2Sn2O7 (R = rare earth) display a host of interesting physical behaviours
+depending on the flavour of rare earth ion. These properties depend on the
+value of the total magnetic moment, the crystal field interactions at each rare
+earth site and the complex interplay between magnetic exchange and long-range
+dipole-dipole interactions. This work focuses on the low temperature physics of
+the dipolar isotropic frustrated antiferromagnetic pyrochlore materials.
+Candidate magnetic ground states are numerically determined at zero temperature
+and the role of quantum spin fluctuations around these states are studied using
+a Holstein-Primakoff spin wave expansion to order 1/S. The results indicate the
+strong stability of the proposed classical ground states against quantum
+fluctuations. The inclusion of long range dipole interactions causes a
+restoration of symmetry and a suppression of the observed anisotropy gap
+leading to an increase in quantum fluctuations in the ground state when
+compared to a model with truncated dipole interactions. The system retains most
+of its classical character and there is little deviation from the fully ordered
+moment at zero temperature.",0403494v1
+2004-06-02,Orbital and magnetic transitions in geometrically-frustrated vanadium spinels -- Monte Carlo study of an effective spin-orbital-lattice coupled model --,"We present our theoretical and numerical results on thermodynamic properties
+and the microscopic mechanism of two successive transitions in vanadium spinel
+oxides $A$V$_2$O$_4$ ($A$=Zn, Mg, or Cd) obtained by Monte Carlo calculations
+of an effective spin-orbital-lattice model in the strong correlation limit.
+Geometrical frustration in the pyrochlore lattice structure of V cations
+suppresses development of spin and orbital correlations, however, we find that
+the model exhibits two transitions at low temperatures. First, a discontinuous
+transition occurs with an orbital ordering assisted by the tetragonal
+Jahn-Teller distortion. The orbital order reduces the frustration in spin
+exchange interactions, and induces antiferromagnetic correlations in
+one-dimensional chains lying in the perpendicular planes to the tetragonal
+distortion. Secondly, at a lower temperature, a three-dimensional
+antiferromagnetic order sets in continuously, which is stabilized by the
+third-neighbor interaction among the one-dimensional antiferromagnetic chains.
+Thermal fluctuations are crucial to stabilize the collinear magnetic state by
+the order-by-disorder mechanism. The results well reproduce the experimental
+data such as transition temperatures, temperature dependence of the magnetic
+susceptibility, changes of the entropy at the transitions, and the magnetic
+ordering structure at low temperatures. Quantum fluctuation effect is also
+examined by the linear spin wave theory at zero temperature. The staggered
+moment in the ground state is found to be considerably reduced from saturated
+value, and reasonably agrees with the experimental data.",0406039v1
+2006-03-27,Jahn-Teller distortions and phase separation in doped manganites,"A ""minimal model"" of the Kondo-lattice type is used to describe a competition
+between the localization and metallicity in doped manganites and related
+magnetic oxides with Jahn-Teller ions. It is shown that the number of itinerant
+charge carriers can be significantly lower than that implied by the doping
+level x. A strong tendency to the phase separation is demonstrated for a wide
+range of intermediate doping concentrations vanishing at low and high doping.
+The phase diagram of the model in the x-T plane is constructed. At low
+temperatures, the system is in a state with a long-range magnetic order:
+antiferromagnetic (AF), ferromagnetic (FM), or AF-FM phase separated (PS)
+state. At high temperatures, there can exist two types of the paramagnetic (PM)
+state with zero and nonzero density of the itinerant electrons. In the
+intermediate temperature range, the phase diagram includes different kinds of
+the PS states: AF-FM, FM-PM, and PM with different content of itinerant
+electrons. The applied magnetic field changes the phase diagram favoring the FM
+ordering. It is shown that the variation of temperature or magnetic field can
+induce the metal-insulator transition in a certain range of doping levels.",0603711v3
+2006-09-15,Magnetic properties of iron nanoparticles prepared by exploding wire technique,"Nanoparticles of iron were prepared in distilled water using very thin iron
+wires and sheets, by the electro-exploding wire technique. Transmission
+electron microscopy reveals the size of the nanoparticles to be in the range 10
+to 50 nm. However, particles of different sizes can be segregated by using
+ultrahigh centrifuge. X-ray diffraction studies confirm the presence of the
+cubic phase of iron. These iron nanoparticles were found to exhibit
+fluorescence in the visible region in contrast to the normal bulk material. The
+room temperature hysteresis measurements upto a field of 1.0 tesla were
+performed on a suspension of iron particles in the solution as well as in the
+powders obtained by filtration. The hysteresis loops indicate that the
+particles are superparamagnetic in nature. The saturation magnetizations was ~
+60 emu / gm. As these iron particles are very sensitive to oxygen a coating of
+non-magnetic iron oxide tends to form around the particles giving it a core -
+shell structure. The core particle size is estimated theoretically from the
+magnetization measurements. Suspensions of iron nanoparticles in water have
+been proposed to be used as an effective decontaminant for ground water.",0609370v1
+2007-01-30,Influence of chemical and magnetic interface properties of Co-Fe-B / MgO / Co-Fe-B tunnel junctions on the annealing temperature dependence of the magnetoresistance,"The knowledge of chemical and magnetic conditions at the Co40Fe40B20 / MgO
+interface is important to interpret the strong annealing temperature dependence
+of tunnel magnetoresistance of Co-Fe-B / MgO / Co-Fe-B magnetic tunnel
+junctions, which increases with annealing temperature from 20% after annealing
+at 200C up to a maximum value of 112% after annealing at 350C. While the well
+defined nearest neighbor ordering indicating crystallinity of the MgO barrier
+does not change by the annealing, a small amount of interfacial Fe-O at the
+lower Co-Fe-B / MgO interface is found in the as grown samples, which is
+completely reduced after annealing at 275C. This is accompanied by a
+simultaneous increase of the Fe magnetic moment and the tunnel
+magnetoresistance. However, the TMR of the MgO based junctions increases
+further for higher annealing temperature which can not be caused by Fe-O
+reduction. The occurrence of an x-ray absorption near-edge structure above the
+Fe and Co L-edges after annealing at 350C indicates the recrystallization of
+the Co-Fe-B electrode. This is prerequisite for coherent tunneling and has been
+suggested to be responsible for the further increase of the TMR above 275C.
+Simultaneously, the B concentration in the Co-Fe-B decreases with increasing
+annealing temperature, at least some of the B diffuses towards or into the MgO
+barrier and forms a B2O3 oxide.",0701749v1
+2007-08-07,Spin and charge orders and their hole-doping dependence in single layered cobaltate La2-xCaxCoO4(0.3<x<0.8),"Neutron scattering experiments were performed on single crystals of layered
+cobalt-oxides La2-xCaxCoO4 (LCCO) to characterize the charge and spin orders in
+a wide hole-doping range of 0.3<x<0.8. For a commensurate value of x=0.5 in
+(H,0,L) plane, two types of superlattice reflections concomitantly appear at
+low temperature; one corresponds to a checkerboard charge ordered pattern of
+Co2+/Co3+ ions and the other is magnetic in origin. Further, the latter
+magnetic-superlattice peaks show two types of symmetry in the reflections,
+suggesting antiferromagnetic-stacking (AF-S) and ferromagnetic-stacking (F-S)
+patterns of spins along the c direction. From the hole-doping dependence, the
+in-plane correlation lengths of both charge and spin orders are found to give a
+maximum at x=0.5. These features are the same with those of x=0.5 in
+La1-xSr1+xMnO4 (LSMO), a typical checkerboard and spin ordered compound.
+However, in (H,H,L) plane, we found a magnetic scattering peak at
+Q=(1/4,1/4,1/2) position below TN. This magnetic peak can not be understood by
+considering the Co2+ spin configuration, suggesting that this peak is
+originated from Co3+ spin order. By analyzing these superlattice reflections,
+we found that they are originated from high-spin state of Co3+ spin order.",0708.0939v1
+2008-01-08,"Nano granular metallic Fe - oxygen deficient TiO$_{2-δ}$ composite films: A room temperature, highly carrier polarized magnetic semiconductor","Nano granular metallic iron (Fe) and titanium dioxide (TiO$_{2-\delta}$) were
+co-deposited on (100) lanthanum aluminate (LaAlO$_3$) substrates in a low
+oxygen chamber pressure using a pulsed laser ablation deposition (PLD)
+technique. The co-deposition of Fe and TiO$_2$ resulted in $\approx$ 10 nm
+metallic Fe spherical grains suspended within a TiO$_{2-\delta}$ matrix. The
+films show ferromagnetic behavior with a saturation magnetization of 3100 Gauss
+at room temperature. Our estimate of the saturation magnetization based on the
+size and distribution of the Fe spheres agreed well with the measured value.
+The film composite structure was characterized as p-type magnetic semiconductor
+at 300 K with a carrier density of the order of $ 10^{22} /{\rm cm^3}$. The
+hole carriers were excited at the interface between the nano granular Fe and
+TiO$_{2-\delta}$ matrix similar to holes excited in the metal/n-type
+semiconductor interface commonly observed in Metal-Oxide-Semiconductor (MOS)
+devices. From the large anomalous Hall effect directly observed in these films
+it follows that the holes at the interface were strongly spin polarized.
+Structure and magneto transport properties suggested that these PLD films have
+potential nano spintronics applications.",0801.1285v1
+2008-03-04,"59Co, 23Na, and 1H NMR Studies of Double-Layer Hydrated Superconductors NaxCoO2-yH2O","We present our NMR studies of double-layer hydrated cobalt oxides
+NaxCoO2-yH2O (x ~ 0.35, y ~ 1.3) with various Tc = 0 - 4.8 K and magnetic
+transition temperatures. High-resolution $^{1}$H NMR spectrum served as an
+evidence for the existence of H$_{3}$O$^{+}$ oxonium ions. $^{23}$Na nuclear
+spin-lattice relaxation rates served to detect local field fluctuations
+sensitive to Tc. $^{59}$Co nuclear quadrupole resonance (NQR) spectra served to
+classify the various Tc samples. From the classification by $^{59}$Co NQR
+frequency, the double-layer hydrated compounds were found to have two
+superconducting phases closely located to a magnetic phase. In the normal state
+and at a magnetic field in the $ab$-plane, two $^{59}$Co NMR signals with
+different Knight shifts and different $^{59}$Co nuclear spin-lattice relaxation
+times $^{59}T_{1}$ were observed. The two $^{59}$Co NMR signals suggest
+magnetic disproportionation of two Co sites or in-plane (XY) anisotropy of a
+single Co site. Non Korringa behavior and power law behavior in zero-field NQR
+1/$^{59}T_{1}$ above and below Tc suggest non-Fermi liquid and unconventional
+superconductivity.",0803.0366v1
+2008-04-24,Modelling Magnetic Fluctuations in the Stripe Ordered State,"The nature of the interplay between superconductivity and magnetism in the
+cuprates remains one of the fundamental unsolved problems in high temperature
+superconductivity. Whether and how these two phenomena are interdependent is
+perhaps most sharply seen in the stripe phases of various copper-oxide
+materials. These phases, involving a mixture of spin and charge density waves,
+do not yet admit a complete, overarching theoretical treatment. However aspects
+of this problem can be analyzed. In this work, we focus on the magnetic side of
+stripe physics. To this end, we study a simple model of a stripe-ordered phase
+consisting of an array of alternating coupled doped and undoped two-leg
+Hubbard-like ladders. To obtain the magnetic response, we employ already
+available dynamical susceptibilities of the individual two-leg ladders and
+treat the interladder coupling in a random phase approximation. Strikingly, we
+find two possible scenarios for the ordered state induced by the coupling
+between ladders: the spin modulation can occur either along or perpendicular to
+the direction of the stripes. These two scenarios are differentiated according
+to different microscopic realizations of the component doped ladders. However
+inelastic neutron scattering experiments on the two stripe ordered cuprates,
+La_{1.875}Ba_{0.125}CuO_4 and La_{2-x}Sr_xCuO_4, do not readily distinguish
+between these two scenarios due to manner in which stripes form in these
+materials.",0804.3832v1
+2008-10-21,A novel approach towards selective bulk synthesis of delaminated graphenes in an electric arc,"Here we demonstrate the selective bulk scale synthesis of delaminated
+graphene sheets by a proper choice of magnetic field modulating an
+electric-arc. An ultra-high purity glassy graphite anode was sublimated in an
+argon atmosphere. Carbon nanotubes, as well as graphene sheets were found
+inside the deposit formed on the cathode. Both the high purity carbon nanotubes
+as well as graphene sheets, with minimal structural defects, were synthesized
+separately by varying the strength and orientation of the external magnetic
+field generated by arrays of permanent magnets. The as-synthesized carbonaceous
+samples were characterized with the help of transmission electron microscopy,
+selected area electron diffraction, Raman spectroscopy and thermogravimetry for
+optimizing the highest selective production of delaminated graphenes. This
+optimization was done by varying the strength and orientation of the external
+magnetic field.
+  The as-synthesized graphene sheets exhibited relatively high degree of
+graphitization and low structural defect density as confirmed by RS. They were
+found to exhibit higher oxidation temperature than that of the carbon
+nanocrystalline particles as inferred from the thermogravimatric analysis.
+Moreover, they were found to form scroll-like carbon nanotubes at their edges
+on account of their surface energy minimization. This was confirmed by the
+selected area electron diffraction analysis. With this new technique, we could
+successfully synthesize delaminated graphenes at a rate of few grams per hour.",0810.3907v1
+2008-10-23,Electron spin blockade and singlet-triplet transition in a silicon single electron transistor,"We investigate a silicon single-electron transistor (SET) in a
+metal-oxide-semiconductor (MOS) structure by applying a magnetic field
+perpendicular to the sample surface. The quantum dot is defined
+electrostatically in a point contact channel and by the potential barriers from
+negatively charged interface traps. The magnetic field dependence of the
+excitation spectrum is primarily driven by the Zeeman effect. In the
+two-electron singlet-triplet (ST) transition, electron-electron Coulomb
+interaction plays a significant role. The evolution of Coulomb blockade peaks
+with magnetic field B is also owing to the Zeeman splitting with no obvious
+orbital effect up to 9 T. The filling pattern shows an alternate
+spin-up-spin-down sequence. The amplitude spectroscopy allows for the
+observation of the spin blockade effect, where the two-electron system forms a
+singlet state at low fields, and the spin polarized injection from the lead
+reduces the tunneling conductance by a factor of 8. At a higher magnetic field,
+due to the ST transition, the spin blockade effect is lifted and the
+conductance is fully recovered.",0810.4268v3
+2009-05-03,Exchange bias in Co/CoO core-shell nanowires: Role of the antiferromagnetic superparamagnetic fluctuations,"The magnetic properties of Co (<D>=15 nm, <L>=130nm) nanowires are reported.
+In oxidized wires, we measure large exchange bias fields of the order of 0.1 T
+below T ~ 100 K. The onset of the exchange bias, between the ferromagnetic core
+and the anti-ferromagnetic CoO shell, is accompanied by a coercivity drop of
+0.2 T which leads to a minimum in coercivity at $\sim100$ K. Magnetization
+relaxation measurements show a temperature dependence of the magnetic viscosity
+S which is consistent with a volume distribution of the CoO grains at the
+surface. We propose that the superparamagnetic fluctuations of the
+anti-ferromagnetic CoO shell play a key role in the flipping of the nanowire
+magnetization and explain the coercivity drop. This is supported by
+micromagnetic simulations. This behavior is specific to the geometry of a 1D
+system which possesses a large shape anisotropy and was not previously observed
+in 0D (spheres) or 2D (thin films) systems which have a high degree of symmetry
+and low coercivities. This study underlines the importance of the AFM
+super-paramagnetic fluctuations in the exchange bias mechanism.",0905.0268v4
+2009-06-16,Microwave Technologies-- Determination of Magnetic and Dielectric Materials Microwave Properties,"In this study, four different techniques are presented. 1 Rectangular
+waveguide measurement technique for normal microwave materials microwave
+properties such as permeability and permittivity. This technique removed guess
+parameter and dispersive effect issues of the old waveguide measurement
+techniques. It projects a new route for determination of any microwave
+materials magnetic and dielectric properties without using any guesses. 2
+Coaxial probe measurement technique for the liquid and biological tissues
+dielectric permittivity. This coaxial probe technique has an advantage which is
+to attain the highest reflected signal from the coaxial probe tip, so that it
+is a fast and very sensitive technique to differentiate lossy materials
+dielectric permittivity. This technique could be useful non destructive
+detections for tumors in hospital and non destructive detections for chemical
+liquids as well. 3 A microstripline measurement technique for oxides microwave
+measurement at low frequency spectra where the waveguide technique becomes
+robot and cumbersome. 4 A new methodology is presented for the rectangular
+waveguide technique to determine microwave metamaterials refractive index,
+permeability and permittivity using the rectangular waveguide. In summary, the
+presented techniques are capable enough to determine magnetic and non magnetic
+solid state materials, liquids, powders and biological tissues microwave
+properties from the broad microwave frequencies spectra between 1 GHz to 50
+GHz. Lastly, a special ferrites microwave properties are also presented since
+the negative refractive index from the insulator ferrite could be an
+interesting subject.",0906.2928v1
+2010-06-30,Electronic Structure of Pyrochlore Iridates: From Topological Dirac Metal to Mott Insulator,"In 5d transition metal oxides such as the iridates, novel properties arise
+from the interplay of electron correlations and spin-orbit interactions. We
+investigate the electronic structure of the pyrochlore iridates, (such as
+Y$_{2}$Ir$_{2}$O$_{7}$) using density functional theory, LDA+U method, and
+effective low energy models. A remarkably rich phase diagram emerges on tuning
+the correlation strength U. The Ir magnetic moment are always found to be
+non-collinearly ordered. However, the ground state changes from a magnetic
+metal at weak U, to a Mott insulator at large U. Most interestingly, the
+intermediate U regime is found to be a Dirac semi-metal, with vanishing density
+of states at the Fermi energy. It also exhibits topological properties -
+manifested by special surface states in the form of Fermi arcs, that connect
+the bulk Dirac points. This Dirac phase, a three dimensional analog of
+graphene, is proposed as the ground state of Y$_{2}$Ir$_{2}$O$_{7}$ and related
+compounds. A narrow window of magnetic `axion' insulator, with axion parameter
+$\theta=\pi$, may also be present at intermediate U. An applied magnetic field
+induces ferromagnetic order and a metallic ground state.",1007.0016v1
+2011-09-04,Resonant soft x-ray scattering from La(1-x)Sr(x)MnO(3) quantum wire arrays,"We describe a strategy for using resonant soft x-ray scattering (RSXS) to
+study the electronic structure of transition metal oxide quantum wires. Using
+electron beam lithography and ion milling, we have produced periodic, patterned
+arrays of colossal magnetoresistance (CMR) phase La(1-x)Sr(x)MnO(3) consisting
+of ~ 5000 wires, each of which is 80 nm in width. The scattered intensity
+exhibits a series of peaks that can be interpreted as Bragg reflections from
+the periodic structure or, equivalently, diffraction orders from the
+grating-like structure. RSXS measurements at the Mn L(2,3) edge, which has a
+large magnetic cross section, show clear evidence for a magnetic superstructure
+with a commensurate period of five wires, which we interpret as commensurately
+modulated antiferromagnetism. This superstructure, which is accompanied by
+non-trivial reorganization of the magnetization within each wire, likely
+results from classical dipole interactions among the wires. We introduce a
+simple, exactly soluble, analytic model of the scattering that captures,
+semi-quantitatively, the primary features in the RSXS data; this model will act
+as a foundation for forthcoming, detailed studies of the magnetic structure in
+these systems.",1109.0734v1
+2011-09-09,Magnetic-field-induced charge-stripe order in the high temperature superconductor YBa2Cu3Oy,"Electronic charges introduced in copper-oxide planes generate high-transition
+temperature superconductivity but, under special circumstances, they can also
+order into filaments called stripes. Whether an underlying tendency of charges
+to order is present in all cuprates and whether this has any relationship with
+superconductivity are, however, two highly controversial issues. In order to
+uncover underlying electronic orders, magnetic fields strong enough to
+destabilise superconductivity can be used. Such experiments, including quantum
+oscillations in YBa2Cu3Oy (a notoriously clean cuprate where charge order is
+not observed) have suggested that superconductivity competes with spin, rather
+than charge, order. Here, using nuclear magnetic resonance, we demonstrate that
+high magnetic fields actually induce charge order, without spin order, in the
+CuO2 planes of YBa2Cu3Oy. The observed static, unidirectional, modulation of
+the charge density breaks translational symmetry, thus explaining quantum
+oscillation results, and we argue that it is most likely the same 4a-periodic
+modulation as in stripe-ordered cuprates. The discovery that it develops only
+when superconductivity fades away and near the same 1/8th hole doping as in
+La2-xBaxCuO4 suggests that charge order, although visibly pinned by CuO chains
+in YBa2Cu3Oy, is an intrinsic propensity of the superconducting planes of high
+Tc cuprates.",1109.2011v1
+2011-09-15,Surface impedance of superconductors with magnetic impurities,"Motivated by the problem of the residual surface resistance of the
+superconducting radio-frequency (SRF) cavities, we develop a microscopic theory
+of the surface impedance of s-wave superconductors with magnetic impurities. We
+analytically calculate the current response function and surface impedance for
+a sample with spatially uniform distribution of impurities, treating magnetic
+impurities in the framework of the Shiba theory. The obtained general
+expressions hold in a wide range of parameter values, such as temperature,
+frequency, mean free path, and exchange coupling strength. This generality, on
+the one hand, allows for direct numerical implementation of our results to
+describe experimental systems (SRF cavities, superconducting qubits) under
+various practically relevant conditions. On the other hand, explicit analytical
+expressions can be obtained in a number of limiting cases, which makes possible
+further theoretical investigation of certain regimes. As a feature of key
+relevance to SRF cavities, we show that in the regime of ""gapless
+superconductivity"" the surface resistance exhibits saturation at zero
+temperature. Our theory thus explicitly demonstrates that magnetic impurities,
+presumably contained in the oxide surface layer of the SRF cavities, provide a
+microscopic mechanism for the residual resistance.",1109.3395v2
+2012-03-28,"Geometric and disorder -- type magnetic frustration in ferrimagnetic ""114"" Ferrites: Role of diamagnetic Li+ and Zn2+ cation substitution","The comparative study of the substitution of zinc and lithium for iron in the
+""114"" ferrites, YBaFe4O7 and CaBaFe4O7, shows that these diamagnetic cations
+play a major role in tuning the competition between ferrimagnetism and magnetic
+frustration in these oxides. The substitution of Li or Zn for Fe in the cubic
+phase YBaFe4O7 leads to a structural transition to a hexagonal phase
+YBaFe4-xMxO7, for M = Li (0.30 < x < 0.75) and for M = Zn (0.40 < x < 1.50). It
+is seen that for low doping values i.e. x = 0.30 (for Li) and x = 0.40 (for
+Zn), these diamagnetic cations induce a strong ferrimagnetic component in the
+samples, in contrast to the spin glass behaviour of the cubic phase. In all the
+hexagonal phases, YBaFe4-xMxO7 and CaBaFe4-xMxO7 with M = Li and Zn, it is seen
+that in the low doping regime (x ~ 0.3 to 0.5), the competition between
+ferrimagnetism and 2 D magnetic frustration is dominated by the average valency
+of iron. In contrast, in the high doping regime (x ~ 1.5), the emergence of a
+spin glass is controlled by the high degree of cationic disorder, irrespective
+of the iron valency.",1203.6220v1
+2012-08-21,High temperature structural and magnetic properties of cobalt nanowires,"We present in this paper the structural and magnetic properties of high
+aspect ratio Co nanoparticles (~10) at high temperatures (up to 623 K) using in
+situ X ray diffraction (XRD) and SQUID characterizations. We show that the
+anisotropic shapes, the structural and texture properties are preserved up to
+500 K. The coercivity can be modelled by u0Hc=2(Kmc+Kshape)/Ms with Kmc the
+magnetocrystalline anisotropy constant, Kshape the shape anisotropy constant
+and Ms the saturation magnetization. Hc decreases linearly when the temperature
+is increased due to the loss of the Co magnetocrystalline anisotropy
+contribution. At 500K, 50% of the room temperature coercivity is preserved
+corresponding to the shape anisotropy contribution only. We show that the
+coercivity drop is reversible in the range 300 - 500 K in good agreement with
+the absence of particle alteration. Above 525 K, the magnetic properties are
+irreversibly altered either by sintering or by oxidation.",1208.4403v2
+2012-10-04,"Spin-state transition, magnetism and local crystal structure in Eu_{1-x}Ca_xCoO_{3-d}","The doping series Eu1-xCaxCoO3-d provides a rather peculiar way to study the
+spin-state transition in cobalt-based complex oxides since partial substitution
+of Eu3+ ions by Ca2+ ions does not increase the mean valence state of cobalt
+but is accompanied by appearance of oxygen vacancies in the ratio d \sim x/2.
+In the parent compound EuCoO3, the low spin (LS)-high spin (HS) transition
+takes place at temperatures so high that the chemical decomposition prevents
+its direct observation. The substitution of Eu3+ for Ca2+ in this system shifts
+the LS-HS transition to lower temperatures. The energy gap associated with this
+transition in octahedrally-coordinated Co3+ ions changes from 1940 K in EuCoO3
+to 1540 K in Eu0.9Ca0.1CoO2.95 and 1050 K in Eu0.8Ca0.2CoO2.9. Besides, each
+O2- vacancy reduces the local coordination of two neighboring Co3+ ions from
+octahedral to pyramidal thereby locally creating magnetically active sites
+which couple into dimers. These dimers at low temperatures form another gapped
+magnetic system with very different energy scale, D~3 K, on the background of
+intrinsically non-magnetic lattice of octahedrally-coordinated low-spin Co3+
+ions.",1210.1289v1
+2015-03-09,Dual gate control of bulk transport and magnetism in the spin-orbit insulator Sr2IrO4,"The 5d iridates have been the subject of much recent attention due to the
+predictions of a large array of novel electronic phases driven by twisting
+strong spin-orbit coupling and Hubbard correlation. As a prototype, the single
+layered perovskite Sr2IrO4 was first revealed to host a Jeff=1/2 Mott
+insulating state. In this material, the approximate energy scale of a variety
+of interactions, involving spin-orbit coupling, magnetic exchange interaction,
+and the Mott gap, allows close coupling among the corresponding physical
+excitations, opening the possibility of cross control of the physical
+properties. Here, we experimentally demonstrate the effective gate control of
+both the transport and magnetism in a Sr2IrO4-based field effect transistor
+using an ionic liquid dielectric. This approach could go beyond the
+surface-limited field effect seen in conventional transistors, reflecting the
+unique aspect of the Jeff=1/2 state. The simultaneous modulation of conduction
+and magnetism confirms the proposed intimate coupling of charge, orbital, and
+spin degrees of freedom in this oxide. These phenomena are probably related to
+an enhanced deviation from the ideal Jeff=1/2 state due to the gate-promoted
+conduction. The present work would have important implications in modelling the
+unusual physics enabled by strong spin-orbit coupling, and provides a new route
+to explore those emergent quantum phases in iridates.",1503.02513v1
+2015-05-14,Morphology control of the magnetization reversal mechanism in Co80Ni20 nanomagnets,"Nanowires with very different size, shape, morphology and crystal symmetry
+can give rise to a wide ensemble of magnetic behaviors whose optimization
+determines their applications in nanomagnets. We present here an experimental
+work on the shape and morphological dependence of the magnetization reversal
+mechanism in weakly interacting Co80Ni20 hexagonal-close-packed nanowires.
+Non-agglomerated nanowires (with length L and diameter d) with a controlled
+shape going from quasi perfect cylinders to diabolos, have been studied inside
+their polyol solution in order to avoid any oxidation process. The coercive
+field HC was found to follow a standard behavior and to be optimized for an
+aspect ratio L/d > 15. Interestingly, an unexpected behavior was observed as
+function of the head morphology leading to the strange situation where a
+diabolo shaped nanowire is a better nanomagnet than a cylinder. This
+paradoxical behavior can be ascribed to the growth-competition between the
+aspect ratio L/d and the head morphology ratio d/D (D being the head width).
+Our experimental results clearly show the importance of the independent
+parameter (t = head thickness) that needs to be considered in addition to the
+shape aspect ratio (L/d) in order to fully describe the nanomagnets magnetic
+behavior. Micromagnetic simulations well support the experimental results and
+bring important insights for future optimization of the nanomagnets morphology",1505.03890v1
+2015-06-08,Coherent Acoustic Perturbation of Second-Harmonic-Generation in NiO,"We investigate the structural and magnetic origins of the unusual ultrafast
+second-harmonicgeneration (SHG) response of femtosecond-laser-excited nickel
+oxide (NiO) previously attributed to oscillatory reorientation dynamics of the
+magnetic structure induced by d-d excitations. Using time-resolved x-ray
+diffraction from the (3/2 3/2 3/2) magnetic planes, we show that changes in the
+magnitude of the magnetic structure factor following ultrafast optical
+excitation are limited to $\Delta<F_m>/<F_m>$ = 1.5% in the first 30 ps. An
+extended investigation of the ultrafast SHG response reveals a strong
+dependence on wavelength as well as characteristic echoes, both of which give
+evidence for an acoustic origin of the dynamics. We therefore propose an
+alternative mechanism for the SHG response based on perturbations of the
+nonlinear susceptibility via optically induced strain in a spatially confined
+medium. In this model, the two observed oscillation periods can be understood
+as the times required for an acoustic strain wave to traverse one coherence
+length of the SHG process in either the collinear or anti-collinear geometries.",1506.02679v1
+2015-08-14,Magnetic fields facilitate DNA-mediated charge transport,"Exaggerate radical-induced DNA damage under magnetic fields is of great
+concerns to medical biosafety and to bio-molecular device based upon DNA
+electronic conductivity. In this report, the effect of applying an external
+magnetic field (MF) on DNA-mediated charge transport (CT) was investigated by
+studying guanine oxidation by a kinetics trap (8CPG) via photoirradiation of
+anthraquinone (AQ) in the presence of an external MF. Positive enhancement in
+CT efficiencies was observed in both the proximal and distal 8CPG after
+applying a static MF of 300 mT. MF assisted CT has shown sensitivities to
+magnetic field strength, duplex structures, and the integrity of base pair
+stacking. MF effects on spin evolution of charge injection upon AQ irradiation
+and alignment of base pairs to CT-active conformation during radical
+propagation were proposed to be the two major factors that MF attributed to
+facilitate DNA-mediated CT. Herein, our results suggested that the electronic
+conductivity of duplex DNA can be enhanced by applying an external MF. MF
+effects on DNA-mediated CT may offer a new avenue for designing DNA-based
+electronic device, and unraveled MF effects on redox and radical relevant
+biological processes.",1508.03512v1
+2016-07-26,Interface-driven topological Hall effect in SrRuO$_3$-SrIrO$_3$ bilayer,"Electron transport coupled with magnetism has attracted attention over the
+years as exemplified in anomalous Hall effect due to a Berry phase in momentum
+space. Another type of unconventional Hall effect -- topological Hall effect,
+originating from the real-space Berry phase, has recently become of great
+importance in the context of magnetic skyrmions. We have observed topological
+Hall effect in bilayers consisting of ferromagnetic SrRuO$_3$ and paramagnetic
+SrIrO$_3$ over a wide region of both temperature and magnetic field. The
+topological term rapidly decreases with the thickness of SrRuO$_3$, ending up
+with the complete disappearance at 7 unit cells of SrRuO$_3$. Combined with
+model calculation, we concluded that the topological Hall effect is driven by
+interface Dzyaloshinskii-Moriya interaction, which is caused by both the broken
+inversion symmetry and the strong spin-orbit coupling of SrIrO$_3$. Such
+interaction is expected to realize the N\'{e}el-type magnetic skyrmion, of
+which size is estimated to be $\sim$10 nm from the magnitude of topological
+Hall resistivity. The results established that the high-quality oxide interface
+enables us to tune the chirality of the system; this can be a step towards the
+future topological electronics.",1607.07536v1
+2018-04-25,Determination of the spin-lifetime anisotropy in graphene using oblique spin precession,"We determine the spin-lifetime anisotropy of spin-polarized carriers in
+graphene. In contrast to prior approaches, our method does not require large
+out-of-plane magnetic fields and thus it is reliable for both low- and
+high-carrier densities. We first determine the in-plane spin lifetime by
+conventional spin precession measurements with magnetic fields perpendicular to
+the graphene plane. Then, to evaluate the out-of-plane spin lifetime, we
+implement spin precession measurements under oblique magnetic fields that
+generate an out-of-plane spin population. We find that the spin-lifetime
+anisotropy of graphene on silicon oxide is independent of carrier density and
+temperature down to 150 K, and much weaker than previously reported. Indeed,
+within the experimental uncertainty, the spin relaxation is isotropic.
+Altogether with the gate dependence of the spin lifetime, this indicates that
+the spin relaxation is driven by magnetic impurities or random spin-orbit or
+gauge fields.",1804.09556v1
+2020-07-28,Defect Induced Room Temperature Ferromagnetism in High Quality Co-doped ZnO Bulk Samples,"The nature of the often reported room temperature ferromagnetism in
+transition metal doped oxides is still a matter of huge debate. Herein we
+report on room temperature ferromagnetism in high quality Co-doped ZnO
+(Zn1-xCoxO) bulk samples synthesized via standard solid-state reaction route.
+Reference paramagnetic Co-doped ZnO samples with low level of structural
+defects are subjected to heat treatments in a reductive atmosphere in order to
+introduce defects in the samples in a controlled way. A detailed structural
+analysis is carried out in order to characterize the induced defects and their
+concentration. The magnetometry revealed the coexistence of a paramagnetic and
+a ferromagnetic phase at room temperature in straight correlation with the
+structural properties. The saturation magnetization is found to increase with
+the intensification of the heat treatment, and, therefore, with the increase of
+the density of induced defects. The magnetic behavior is fully explained in
+terms of the bound magnetic polaron model. Based on the experimental findings,
+supported by theoretical calculations, we attribute the origin of the observed
+defect-induced-ferromagnetism to the ferromagnetic coupling between the Co ions
+mediated by magnetic polarons due to zinc interstitial defects.",2007.14140v1
+2013-08-05,Physics picture from neutron scattering study on Fe-based superconductors,"Neutron scattering, with its ability to measure the crystal structure, the
+magnetic order, and the structural and magnetic excitations, plays an active
+role in investigating various families of Fe-based high-Tc superconductors.
+Three different types of antiferromag- netic orders have been discovered in the
+Fe plane, but two of them cannot be explained by the spin-density-wave (SDW)
+mechanism of nesting Fermi surfaces. Noticing the close relation between
+antiferromagnetic order and lattice distortion in orbital ordering from
+previous studies on manganites and other oxides, we have advocated orbital or-
+dering as the underlying common mechanism for the structural and
+antiferromagnetic transitions in the 1111, 122 and 11 parent compounds. We
+observe the coexistence of antiferromagnetic order and superconductivity in the
+(Ba,K)Fe2 As2 system, when its phase separation is generally accepted. Optimal
+Tc is proposed to be controlled by the local FeAs4 tetrahedron from our
+investigation on the 1111 materials. The Bloch phase coherence of the Fermi
+liquid is found crucial to the occurrence of bulk superconductiv- ity in iron
+chalcogenides of both the 11 and the 245 families. Iron chalcogenides carry a
+larger staggered magnetic moment (> 2{\mu}B /Fe) than that in iron pnictides (<
+1{\mu}B /Fe) in the antiferromagnetic order. Normal state magnetic excitations
+in the 11 supercon- ductor are of the itinerant nature while in the 245
+superconductor the spin-waves of localized moments. The observation of
+superconducting resonance peak provides a cru- cial piece of information in
+current deliberation of the pairing symmetry in Fe-based superconductors.",1308.1040v1
+2014-06-13,Low Energy Electrodynamics of Novel Spin Excitations in the Quantum Spin Ice Yb$_2$Ti$_2$O$_7$,"In condensed matter systems, the formation of long range order (LRO) with
+broken symmetry is often accompanied by new types of excitations. However, in
+many magnetic pyrochlore oxides, geometrical frustration suppresses
+conventional LRO while at the same time non-trivial spin correlations are
+observed. For such materials, a natural question to ask then is what is the
+nature of the excitations in this highly correlated state without broken
+symmetry? Frequently the application of a symmetry breaking field can stabilize
+excitations whose properties still reflect certain aspects of the anomalous
+state without long-range order. Here we report evidence of novel magnetic
+excitations in the quantum spin ice material Yb$_2$Ti$_2$O$_7$, obtained from
+time-domain terahertz spectroscopy (TDTS). At large fields, both magnon and
+two-magnon-like excitations are observed in a $<$001$>$ directed magnetic field
+illustrating the stabilization of a field induced LRO state. The unique ability
+of TDTS to measure complex response functions allows a direct study of magnetic
+responses in different polarization channels, revealing the existence of an
+unusual left-hand polarized magnon. The g-factors of these excitations are
+dramatically enhanced in the low-field limit, showing a cross-over of these
+one- and two-magnon states into features consistent with quantum string-like
+excitations proposed to exist in quantum spin ice in a small $<$001$>$ applied
+field.",1406.3576v1
+2016-12-15,Ba2NiOsO6: A Dirac-Mott insulator with ferromagnetism near 100 K,"The ferromagnetic semiconductor Ba2NiOsO6 (Tmag ~100 K) was synthesized at 6
+GPa and 1500 {\deg}C. It crystallizes into a double perovskite structure
+[Fm-3m; a = 8.0428(1) {\AA}], where the Ni2+ and Os6+ ions are perfectly
+ordered at the perovskite B-site. We show that the spin-orbit coupling of Os6+
+plays an essential role in opening the charge gap. The magnetic state was
+investigated by density functional theory calculations and powder neutron
+diffraction. The latter revealed a collinear ferromagnetic order in a >21 kOe
+magnetic field at 5 K. The ferromagnetic gapped state is fundamentally
+different from that of known dilute magnetic semiconductors such as (Ga,Mn)As
+and (Cd,Mn)Te (Tmag < 180 K), the spin-gapless semiconductor Mn2CoAl (Tmag ~720
+K), and the ferromagnetic insulators EuO (Tmag ~70 K) and Bi3Cr3O11 (Tmag ~220
+K). It is also qualitatively different from known ferrimagnetic
+insulator/semiconductors, which are characterized by an antiparallel spin
+arrangement. Our finding of the ferromagnetic semiconductivity of Ba2NiOsO6
+should increase interest in the platinum group oxides, because this new class
+of materials should be useful in the development of spintronic, quantum
+magnetic, and related devices.",1612.05041v1
+2016-12-15,Covalency and vibronic couplings make a nonmagnetic j=3/2 ion magnetic,"For 4$d^1$ and 5$d^1$ spin-orbit-coupled electron configurations, the notion
+of nonmagnetic j=3/2 quartet ground state discussed in classical textbooks is
+at odds with the observed variety of magnetic properties. Here we throw fresh
+light on the electronic structure of 4$d^1$ and 5$d^1$ ions in molybdenum- and
+osmium-based double-perovskite systems and reveal different kinds of on-site
+many-body physics in the two families of compounds: while the sizable magnetic
+moments and $g$ factors measured experimentally are due to both metal
+$d$-ligand $p$ hybridization and dynamic Jahn-Teller interactions for 4$d$
+electrons, it is essentially $d$-$p$ covalency for the 5$d^1$ configuration.
+These results highlight the subtle interplay of spin-orbit interactions,
+covalency and electron-lattice couplings as the major factor in deciding the
+nature of the magnetic ground states of 4$d$ and 5$d$ quantum materials. Cation
+charge imbalance in the double-perovskite structure is further shown to allow a
+fine tuning of the gap between the $t_{2g}$ and $e_g$ levels, an effect of much
+potential in the context of orbital engineering in oxide electronics.",1612.05158v1
+2017-06-25,Frustration-driven C4 symmetric orders in a hetero-structured iron-based superconductor,"A subtle balance between competing interactions in strongly correlated
+systems can be easily tipped by additional interfacial interactions in a
+heterostructure. This often induces exotic phases with unprecedented
+properties, as recently exemplified by high-Tc superconductivity in FeSe
+monolayer on the nonmagnetic SrTiO3. When the proximity-coupled layer is
+magnetically active, even richer phase diagrams are expected in iron-based
+superconductors (FeSCs), which however has not been explored due to the lack of
+a proper material system. One promising candidate is Sr2VO3FeAs, a
+naturally-assembled heterostructure of a FeSC and a Mott-insulating vanadium
+oxide. Here, using high-quality single crystals and high-accuracy 75As and 51V
+nuclear magnetic resonance (NMR) measurements, we show that a novel electronic
+phase is emerging in the FeAs layer below T0 ~ 155 K without either static
+magnetism or a crystal symmetry change, which has never been observed in other
+FeSCs. We find that frustration of the otherwise dominant Fe stripe and V Neel
+fluctuations via interfacial coupling induces a charge/orbital order with
+C4-symmetry in the FeAs layers, while suppressing the Neel antiferromagnetism
+in the SrVO3 layers. These findings demonstrate that the magnetic proximity
+coupling is effective to stabilize a hidden order in FeSCs and, more generally,
+in strongly correlated heterostructures.",1706.08157v1
+2018-01-30,"Crystalline structure and XMCD studies of Co40Fe40B20 grown on Bi2Te3, BiTeI and Bi2Se3","Epitaxial films of Co40Fe40B20 (further - CoFeB) were grown on Bi2Te3(001)
+and Bi2Se3(001) substrates by laser molecular beam epitaxy (LMBE) technique at
+200-400C. Bcc-type crystalline structure of CoFeB with (111) plane parallel to
+(001) plane of Bi2Te3 was observed, in contrast to polycrystalline CoFeB film
+formed on Bi2Se3(001) at RT using high-temperature seeding layer. Therefore,
+structurally ordered ferromagnetic thin films were obtained on the topological
+insulator surface for the first time. Using high energy electron diffraction
+(RHEED) 3D reciprocal space mapping, epitaxial relations of main
+crystallographic axes for the CoFeB/ Bi2Te3 heterostructure were revealed. MOKE
+and AFM measurements showed the isotropic azimuthal in-plane behavior of
+magnetization vector in CoFeB/ Bi2Te3, in contrast to 2nd order magnetic
+anisotropy seen in CoFeB/Bi2Se3. XPS measurements showed more stable behavior
+of CoFeB grown on Bi2Te3 to the oxidation, in compare to CoFeB grown on Bi2Se3.
+XAS and XMCD measurements of both concerned nanostructures allowed calculation
+of spin and orbital magnetic moments for Co and Fe. Additionally, crystalline
+structure and XMCD response of the CoFeB/BiTeI and Co55Fe45/BiTeI systems were
+studied, epitaxial relations of main crystallographic axes were found, and spin
+and orbital magnetic moments were calculated.",1801.10061v1
+2018-10-03,Stable hump-like Hall effect and non-coplanar spin textures in SrRuO$_3$ ultrathin film,"We observed a hump-like feature in Hall effects of SrRuO$_3$ ultrathin films,
+and systematically investigated it with controlling thicknesses, temperatures
+and magnetic fields. The hump-like feature is extremely stable, even surviving
+as a magnetic field is tilted by as much as 85$^\circ$. Based on the
+atomic-level structural analysis of a SrRuO$_3$ ultrathin film with a
+theoretical calculation, we reveal that atomic rumplings at the thin-film
+surface enhance Dzyaloshinskii-Moriya interaction, which can generate stable
+chiral spin textures and a hump-like Hall effect. Moreover, temperature
+dependent resonant X-ray measurements at Ru L-edge under a magnetic field
+showed that the intensity modulation of unexpected peaks was correlated with
+the hump region in the Hall effect. We verify that the two-dimensional property
+of ultrathin films generates stable non-coplanar spin textures having a
+magnetic order in a ferromagnetic oxide material.",1810.01615v2
+2019-06-10,Anomalous electron transport in epitaxial NdNiO$_3$ films,"The origin of simultaneous electronic, structural and magnetic transitions in
+bulk rare-earth nickelates ($RE$NiO$_3$) remains puzzling with multiple
+conflicting reports on the nature of these entangled phase transitions.
+Heterostructure engineering of these materials offers unique opportunity to
+decouple metal-insulator transition (MIT) from the magnetic transition.
+However, the evolution of underlying electronic properties across these
+decoupled transitions remains largely unexplored. In order to address this, we
+have measured Hall effect on a series of epitaxial NdNiO$_3$ films, spanning a
+variety of electronic and magnetic phases. We find that the MIT results in only
+partially gapped Fermi surface, whereas full insulating phase forms below the
+magnetic transition. In addition, we also find a systematic reduction of the
+Hall coefficient ($R_H$) in the metallic phase of these films with epitaxial
+strain and also a surprising transition to negative value at large compressive
+strain. Partially gapped weakly insulating, paramagnetic phase is reminiscence
+of pseudogap behavior of high $T_c$ cuprates. The precursor metallic phase,
+which undergoes transition to insulating phase is a non-Fermi liquid with the
+temperature exponent ($n$) of resistivity of 1, whereas the exponent increases
+to 4/3 in the non-insulating samples. Such nickelate phase diagram with
+sign-reversal of $R_H$, pseudo-gap phase and non Fermi liquid behavior are
+intriguingly similar to high $T_c$ cuprates, giving important guideline to
+engineer unconventional superconductivity in oxide heterostructure.",1906.03809v1
+2019-09-06,Octupolar order in d-orbital Mott insulators,"Motivated by experimental and theoretical interest in realizing multipolar
+orders in $d$-orbital materials, we discuss the quantum magnetism of $J\!=\!2$
+ions which can be realized in spin-orbit coupled oxides with $5d^2$ transition
+metal ions. Based on the crystal field environment, we argue for a splitting of
+the $J\!=\!2$ multiplet, leading to a low lying non-Kramers doublet which hosts
+quadrupolar and octupolar moments. We discuss a microscopic mechanism whereby
+the combined perturbative effects of orbital repulsion and antiferromagnetic
+Heisenberg spin interactions leads to ferro-octupolar coupling between
+neighboring sites, and stabilizes ferro-octupolar order for a face-centered
+cubic lattice. This same mechanism is also shown to disfavor quadrupolar
+ordering. We show that studying crystal field levels via Raman scattering in a
+magnetic field provides a probe of octupolar order. We study spin dynamics in
+the ferro-octupolar state using a slave-boson approach, uncovering a gapped and
+dispersive magnetic exciton. For sufficiently strong magnetic exchange, the
+dispersive exciton can condense, leading to conventional type-I
+antiferromagnetic (AFM) order which can preempt octupolar order. Our proposal
+for ferrooctupolar order, with specific results in the context of a model
+Hamiltonian, provides a comprehensive understanding of thermodynamics, $\mu$SR,
+X-ray diffraction, and inelastic neutron scattering measurements on a range of
+cubic $5d^2$ double perovskite materials including Ba$_2$ZnOsO$_6$,
+Ba$_2$CaOsO$_6$, and Ba$_2$MgOsO$_6$. Our proposal for exciton condensation
+leading to type-I AFM order may be relevant to materials such as
+Sr$_2$MgOsO$_6$.",1909.03089v3
+2019-09-11,Giant pressure-enhancement of multiferroicity in CuBr2,"Type-II multiferroic materials, in which ferroelectric polarization is
+induced by inversion non-symmetric magnetic order, promise new and highly
+efficient multifunctional applications based on the mutual control of magnetic
+and electric properties. Although this phenomenon has to date been limited to
+low temperatures, here we report a giant pressure-dependence of the
+multiferroic critical temperature in CuBr$_2$. At 4.5 GPa, $T_\mathrm{C}$ is
+enhanced from 73.5 to 162 K, to our knowledge the highest value yet reported
+for a non-oxide type-II multiferroic. This growth shows no sign of saturating
+and the dielectric loss remains small under these high pressures. We establish
+the structure under pressure and demonstrate a 60\% increase in the two-magnon
+Raman energy scale up to 3.6 GPa. First-principles structural and magnetic
+energy calculations provide a quantitative explanation in terms of dramatically
+pressure-enhanced interactions between CuBr$_2$ chains. These large,
+pressure-tuned magnetic interactions motivate structural control in cuprous
+halides as a route to applied high-temperature multiferroicity.",1909.04989v2
+2019-10-09,Controlling magnetisation's reversal mechanism and hyperthermia efficiency in core/shell magnetic nanoparticles by tuning the interphase coupling,"Magnetic particle hyperthermia, in which colloidal nanostructures are exposed
+to an alternating magnetic field, is a promising approach to cancer therapy.
+Unfortunately, the clinical efficacy of hyperthermia has not yet been
+optimized. Consequently, routes to improve magnetic particle hyperthermia such
+as designing hybrid structures comprised from different phase materials are
+actively pursued. Here we demonstrate enhanced hyperthermia efficiency in
+relative large spherical Fe/Fe-oxide core/shell nanoparticles through the
+manipulation of interactions between the core and shell phases. Experimental
+results on exemplary samples with diameters in the range 30-80 nm indicated a
+direct correlation of hysteresis losses to the observed temperature elevation
+rate with a maximum efficiency of around 0.9 kW/g. The absolute particle size,
+the core/shell ratio, and the interposition of a thin w\""ustite interlayer, are
+shown to have powerful effects on the specific absorption rate. By comparing
+our measurements to micromagnetic calculations we have unveiled topologically
+non-trivial magnetisation reversal modes under which interparticle interactions
+become negligible, aggregates formation is minimized, and the energy that is
+converted into heat is increased. This information has been overlooked till
+date and is in stark contrast to the existing knowledge on homogeneous
+particles.",1910.03914v1
+2019-10-23,Multi-messenger nano-probes of hidden magnetism in a strained manganite,"The ground state properties of correlated electron systems can be
+extraordinarily sensitive to external stimuli, such as temperature, strain, and
+electromagnetic fields, offering abundant platforms for functional materials.
+We present a metastable and reversible photoinduced ferromagnetic transition in
+strained films of the doped manganite La(2/3)Ca(1/3)MnO3. Using the novel
+multi-messenger combination of atomic force microscopy, cryogenic scanning
+near-field optical microscopy, magnetic force microscopy, and ultrafast laser
+excitation, we demonstrate both ""writing"" and ""erasing"" of a metastable
+ferromagnetic metal phase with nanometer-resolved finesse. By tracking both
+optical conductivity and magnetism at the nano-scale, we reveal how spontaneous
+strain underlies the thermal stability, persistence, and reversal of this
+photoinduced metal. Our first-principles electronic structure calculations
+reveal how an epitaxially engineered Jahn-Teller distortion can stabilize
+nearly degenerate antiferromagnetic insulator and ferromagnetic metal phases.
+We propose a Ginzburg-Landau description to rationalize the co-active interplay
+of strain, lattice distortion, and magnetism we resolve in strained LCMO, thus
+guiding future functional engineering of epitaxial oxides like manganites into
+the regime of phase-programmable materials.",1910.10361v1
+2020-04-20,Current-induced torque originating from orbital current,"The electrical manipulation of magnetization by current-induced spin torques
+has given access to realize a plethora of ultralow power and fast spintronic
+devices such as non-volatile magnetic memories, spin-torque nano-oscillators,
+and neuromorphic computing devices. Recent advances have led to the notion that
+relativistic spin-orbit coupling is an efficient source for current-induced
+torques, opening the field of spin-orbitronics. Despite the significant
+progress, however, the fundamental mechanism of magnetization manipulation, the
+requirement of spin currents in generating current-induced torques, has
+remained unchanged. Here, we demonstrate the generation of current-induced
+torques without the use of spin currents. By measuring the current-induced
+torque for naturally-oxidized-Cu/ferromagnetic-metal bilayers, we observed an
+exceptionally high effective spin Hall conductivity at low temperatures despite
+the absence of strong spin-orbit coupling. Furthermore, we found that the
+direction of the torque depends on the choice of the ferromagnetic layer, which
+counters the conventional understanding of the current-induced torque. These
+unconventional features are best interpreted in terms of an orbital counterpart
+of the spin torque, an orbital torque, which arises from the orbital Rashba
+effect and orbital current. These findings will shed light on the underlying
+physics of current-induced magnetization manipulation, potentially altering the
+landscape of spin-orbitronics.",2004.09165v1
+2017-05-08,"Relaxor ferroelectric behavior and intrinsic magnetodielectric behavior near room temperature in Li2Ni2Mo3O12, a compound with distorted honeycomb and spin-chains","Keeping current interests to identify materials with intrinsic
+magnetodielectric behavior near room temperature and with novel pyroelectric
+current anomalies, we report temperature and magnetic-field dependent behavior
+of complex dielectric permittivity and pyroelectric current for an oxide,
+Li2Ni2Mo3O12, containing magnetic ions with (distorted) honey-comb and chain
+arrangement and ordering magnetically below 8 K. The dielectric data reveal the
+existence of relaxor ferroelectricity behavior in the range 160-240 K and there
+are corresponding Raman mode anomalies as well in that temperature range.
+Pyrocurrent behavior is also consistent with this interpretation, with the
+pyrocurrent peak-temperature interestingly correlating with the poling
+temperature. 7Li NMR offer an evidence for crystallographic disorder intrinsic
+to this compound and we therefore conclude that such a disorder is apparently
+responsible for the randomness of local electric field leading to relaxor
+ferroelectric property. Another observation of emphasis is that there is a
+notable decrease in the dielectric constant with the application of magnetic
+field to the tune of about -2.4% at 300 K, with the magnitude varying
+mariginally with temperature. Small loss factor values validate intrinsic
+behavior of the magnetodielectric effect at room temperature.",1705.02855v1
+2017-09-12,Control of magnetic anisotropy by orbital hybridization in (La0.67Sr0.33MnO3)n/(SrTiO3)n superlattice,"The asymmetry of chemical nature at the hetero-structural interface offers an
+unique opportunity to design desirable electronic structure by controlling
+charge transfer and orbital hybridization across the interface. However, the
+control of hetero-interface remains a daunting task. Here, we report the
+modulation of interfacial coupling of (La0.67Sr0.33MnO3)n/(SrTiO3)n
+superlattices by manipulating the periodic thickness with n unit cells of
+SrTiO3 and n unit cells La0.67Sr0.33MnO3. The easy axis of magnetic anisotropy
+rotates from in-plane (n = 10) to out-of-plane (n = 2) orientation at 150 K.
+Transmission electron microscopy reveals enlarged tetragonal ratio > 1 with
+breaking of volume conservation around the (La0.67Sr0.33MnO3)n/(SrTiO3)n
+interface, and electronic charge transfer from Mn to Ti 3d orbitals across the
+interface. Orbital hybridization accompanying the charge transfer results in
+preferred occupancy of 3d3z2-r2 orbital at the interface, which induces a
+stronger electronic hopping integral along the out-of-plane direction and
+corresponding out-of-plane magnetic easy axis for n = 2. We demonstrate that
+interfacial orbital hybridization in superlattices of strongly correlated
+oxides may be a promising approach to tailor electronic and magnetic properties
+in device applications.",1709.03903v1
+2018-07-04,"Spin-orbit coupling driven insulating state in hexagonal iridates Sr3MIrO6 (M = Sr, Na and Li)","The spin-orbit coupling (SOC) interactions, electron correlation effects and
+Hund coupling cooperate and compete with each other, leading to novel
+properties, quantum phase and non-trivial topological electronic behavior in
+iridium oxides. Because of the well separated IrO6 octahedra approaching cubic
+crystal-field limit, the hexagonal iridates Sr3MIrO6 (M = Sr, Na and Li) serves
+as a canonical model system to investigate the underlying physical properties
+that arises from the novel Jeff state. Based on density functional theory
+calculations complemented by Green's function methods, we systematically
+explore the critical role of SOC on the electronic structure and magnetic
+properties of Sr3MIrO6. The crystal-field splitting combined with correlation
+effects are insufficient to account for the insulating nature, but the SOC
+interactions is the intrinsic source to trigger the insulating ground states in
+these hexagonal iridates. The decreasing geometry connectivity of IrO6
+octahedra gives rise to the increasing of effective electronic correlations and
+SOC interactions, tuning the hexagonal iridates from low-spin Jeff = 1/2 states
+with large local magnetic moments for the Ir4+ (5d5) ions in Sr4IrO6 to
+nonmagnetic singlet Jeff = 0 states without magnetic moments for the Ir5+ (5d4)
+ions in Sr3NaIrO6 and Sr3LiIrO6. The theoretical calculated results are in good
+agreement with available experimental data, and explain the magnetic properties
+of Sr3MIrO6 well.",1807.01807v1
+2019-03-19,Kitaev quantum spin liquid - concept and materialization,"A decade ago, Alexei Kitaev proposed an exactly solvable $S$ = 1/2 model on a
+two-dimensional honeycomb lattice, where the spins fractionalize into Majorana
+fermions and form a topological quantum spin liquid (QSL) in the ground state.
+It was soon recognized that a family of complex iridium oxides, as well as
+ruthenium chloride, with honeycomb structure are magnetic insulators and
+accommodate essential ingredients of the Kitaev model, due to the interplay of
+electron correlation and spin-orbit coupling. This initiated a race to
+materialize the Kitaev QSL and to capture the signature of Majorana fermions.
+In this review, we provide a wide perspective of this rapidly growing field,
+including theory, materials and experiment. We first summarize the theoretical
+background of the Kitaev QSL ground state and its materialization using
+spin-orbital-entangled $J_{\rm eff}$ = 1/2 moments. This is followed by an
+overview of candidate materials and their magnetic properties, including
+Na$_2$IrO$_3$, $\alpha$, $\beta$, $\gamma$-Li$_2$IrO$_3$,$\alpha$-RuCl$_3$ and
+H$_3$LiIr$_2$O$_6$. Finally, we review the latest exciting progress in the
+search for the Kitaev QSL. In particular, H$_3$LiIr$_2$O$_6$ and
+$\alpha$-RuCl$_3$ in applied magnetic field show signatures of the QSL state,
+and $\alpha$-RuCl$_3$ has unusual magnetic excitations and thermal transport
+properties that are consistent with spin fractionalization.",1903.08081v1
+2019-08-18,Electron g-factor engineering for non-reciprocal spin photonics,"We study the interplay of electron and photon spin in non-reciprocal
+materials. Traditionally, the primary mechanism to design non-reciprocal
+photonic devices has been magnetic fields in conjunction with magnetic oxides,
+such as iron garnets. In this work, we present an alternative paradigm that
+allows tunability and reconfigurability of the non-reciprocity through
+spintronic approaches. The proposed design uses the high-spin-orbit coupling of
+a narrow-band gap semiconductor (InSb) with ferromagnetic dopants. A
+combination of the intrinsic and a gate-applied electric field gives rise to a
+strong external Rashba spin-orbit coupling (RSOC) in a magnetically doped InSb
+film. The RSOC which is gate alterable is shown to adjust the magnetic
+permeability tensor via the electron g-factor of the medium. We use electronic
+band structure calculations (k$\cdot$p theory) to show the gate-adjustable RSOC
+manifest itself in the non-reciprocal coefficient of photon fields via shifts
+in the Kerr and Faraday rotations. In addition, we show that photon spin
+properties of dipolar emitters placed in the vicinity of a non-reciprocal
+electromagnetic environment is distinct from reciprocal counterparts. The
+Purcell factor (F$_{p}$) of a spin-polarized emitter (right-handed circular
+dipole) is significantly enhanced due to a larger g-factor while a left-handed
+dipole remains essentially unaffected. Our work can lead to electron spin
+controlled reconfigurable non-reciprocal photonic devices.",1908.06393v2
+2019-11-11,Atomic Origin of Spin-Valve Magnetoresistance at the SrRuO3 Grain Boundary,"Defects ubiquitously exist in crystal materials and usually exhibit a very
+different nature than the bulk matrix, and hence, their presence can have
+significant impacts on the properties of devices. Although it is well accepted
+that the properties of defects are determined by their unique atomic
+environments, the precise knowledge of such relationships is far from clear for
+most oxides due to the complexity of defects and difficulties in
+characterization. Here, we fabricate a 36.8{\deg} SrRuO3 grain boundary of
+which the transport measurements show a spin-valve magnetoresistance. We
+identify its atomic arrangement, including oxygen, using scanning transmission
+electron microscopy and spectroscopy. Based on the as-obtained atomic
+structure, the density functional theory calculations suggest that the
+spin-valve magnetoresistance is because of the dramatically reduced magnetic
+moments at the boundary. The ability to manipulate magnetic properties at the
+nanometer scale via defect control allows new strategies to design
+magnetic/electronic devices with low-dimensional magnetic order.",1911.04108v1
+2020-05-21,Enhancement of perpendicular magnetic anisotropy and Dzyaloshinskii-Moriya interaction in thin ferromagnetic films by atomic-scale modulation of interfaces,"To stabilize the non-trivial spin textures, e.g., skyrmions or chiral domain
+walls in ultrathin magnetic films, an additional degree of freedom such as the
+interfacial Dzyaloshinskii-Moriya interaction (IDMI) must be induced by the
+strong spin-orbit coupling (SOC) of a stacked heavy metal layer. However,
+advanced approaches to simultaneously control IDMI and perpendicular magnetic
+anisotropy (PMA) are needed for future spin-orbitronic device implementations.
+Here, we show an effect of atomic-scale surface modulation on the magnetic
+properties and IDMI in ultrathin films composed of 5d heavy
+metal/ferromagnet/4d(5d) heavy metal or oxide interfaces, such as
+Pt/CoFeSiB/Ru, Pt/CoFeSiB/Ta, and Pt/CoFeSiB/MgO. The maximum IDMI value
+corresponds to the correlated roughness of the bottom and top interfaces of the
+ferromagnetic layer. The proposed approach for significant enhancement of PMA
+and IDMI through the interface roughness engineering at the atomic scale offers
+a powerful tool for the development of the spin-orbitronic devices with the
+precise and reliable controllability of their functionality.",2005.10584v1
+2020-09-23,Magnetodielectric coupling and multi-blocking effect in the Ising-chain magnet Sr2Ca2CoMn2O9,"We have demonstrated magnetodielectric (MD) coupling in an Ising-chain magnet
+Sr2Ca2CoMn2O9, via detailed investigation of ac susceptibility and dielectric
+constant as a function of temperature, magnetic field and frequency.
+Sr2Ca2CoMn2O9 consists of spin-chains, made of the regular stacking of one CoO6
+trigonal prism with two MnO6 octahedra. The (Co2+ Mn4+ Mn4+) unit stabilizes a
+(up-down-up) spin-state along the chains which are distributed on a triangular
+lattice. This compound undergoes a partially disordered antiferromagnetic
+transition at TN ~ 28 K. The dielectric constant exhibits a clear peak at TN
+only in presence of an external magnetic field (above 5 kOe), evidencing the
+presence of MD coupling, which is further confirmed by field-dependent
+dielectric measurements. We argue that spatial inversion symmetry can be broken
+as a result of exchange-striction along each spin chain, inducing uncompensated
+local dipoles. At low temperatures, a dipolar relaxation phenomenon is
+observed, bearing strong similarities with the blocking effect typical of the
+spin dynamics in this compound. Such a spin-dipole relationship is referred to
+as a multi-blocking effect, in relation with the concept of magnetodielectric
+multiglass previously introduced for related materials.",2009.10969v2
+2020-09-26,"Electroferrofluids with non-equilibrium voltage-controlled magnetism, interfaces, and patterns","Materials with continuous dissipation can exhibit responses and
+functionalities that are not possible in thermodynamic equilibrium. While this
+concept is well-known, a major challenge has been the implementation: how to
+rationally design materials with functional non-equilibrium states and quantify
+the dissipation? Here we address these questions for the widely used colloidal
+nanoparticles that convey several functionalities. We propose that useful
+non-equilibrium states can be realised by creating and maintaining steady-state
+nanoparticle concentration gradients by continuous injection and dissipation of
+energy. We experimentally demonstrate this with superparamagnetic iron oxide
+nanoparticles that in thermodynamic equilibrium form a homogeneous functional
+fluid with a strong magnetic response (a ferrofluid). To create non-equilibrium
+functionalities, we charge the nanoparticles with anionic charge control agents
+to create electroferrofluids where nanoparticles act as charge carriers that
+can be driven with electric fields and current to non-homogeneous dissipative
+steady-states. The dissipative steady-states exhibit voltage-controlled
+magnetic properties and emergent diffuse interfaces. The diffuse interfaces
+respond strongly to external magnetic fields, leading to dissipative patterns
+that are not possible in the equilibrium state. We identify the closest
+non-dissipative analogues of these dissipative patterns, discuss the
+differences, and highlight how pattern formation in electroferrofluids is
+linked to dissipation that can be directly quantified. Beyond electrically
+controlled ferrofluids and patterns, we foresee that the concept can be
+generalized to other functional nanoparticles to create various scientifically
+and technologically relevant non-equilibrium states with optical, electrical,
+catalytic, and mechanical responses that are not possible in thermodynamic
+equilibrium.",2009.12563v1
+2020-10-11,Stripes in oxygen-enriched cuprates,"Charge-order stripes of different types occur when copper oxides are doped
+with either heterovalent metal, like $La_{2-x}Sr_xCuO_4$, or oxygen, like
+$YBa_2Cu_3O_{6+y}$. The difference shows up in the doping dependence of their
+incommensurability: $q_c(x) \propto \sqrt{x-\check{p}}$ but $q_c(y) \approx
+0.3$. The square-root dependence in the former compound family results from
+Coulomb repulsion between doped holes (or electrons), residing pairwise in
+lattice-site $O$ (or $Cu$) atoms of the $CuO_2$ planes. The almost constant
+$q_c(y)$ value in the second family results from the aggregation of ozone-like
+molecules, formed from $O^{2-}$ ions of the host with embedded oxygen atoms,
+$O_i$, at interstitial sites in the $CuO_2$ planes. The magnetic moments,
+$\mathbf{m}(O)$, of the lattice-defect $O$ atoms in the first family arrange
+antiferromagnetically, which gives rise to accompanying magnetization stripes
+of incommensurability $q_m(x) = q_c(x)/2$. The ozone complexes have a vanishing
+magnetic moment, $\mathbf{m}=0$, which explains the absence of accompanying
+magnetization stripes in the second family. Embedding excess oxygen as $O_i$
+atoms in $CuO_2$ planes is likewise assumed for $HgBa_2CuO_{4+\delta}$ and
+oxygen-enriched bismuth cuprates. A combination of characteristics from both
+families is present in oxygen-enriched $La_2CuO_{4+y}$. The validity of
+determining the hole density in oxygen-enriched cuprates with the
+universal-dome method is independently confirmed. Besides causing different
+types of stripes, the two types of lattice-defect oxygen may also cause
+different types of superconductivity. This could explain the much higher
+$T_{c,max}$ in oxygen-enriched than $Sr$-doped cuprates, as well as the cusped
+cooling-curves of X-ray intensity diffracted by stripes in the former family.",2010.06388v2
+2020-11-12,Effective Magnetic Hamiltonian at Finite Temperatures for Rare Earth Chalcogenides,"Alkali metal rare-earth chalcogenide $ARECh2$ (A=alkali or monovalent metal,
+RE=rare earth, Ch=O, S, Se, Te), is a large family of quantum spin liquid (QSL)
+candidates we discovered recently. Unlike $YbMgGaO4$, most members in the
+family except for the oxide ones, have relatively small crystalline
+electric-field (CEF) excitation levels, particularly the first ones. This makes
+the conventional Curie-Weiss analysis at finite temperatures inapplicable and
+CEF excitations may play an essential role in understanding the low-energy spin
+physics. Here we considered an effective magnetic Hamiltonian incorporating CEF
+excitations and spin-spin interactions, to accurately describe thermodynamics
+in such a system. By taking $NaYbSe2$ as an example, we were able to analyze
+magnetic susceptibility, magnetization under pulsed high fields and heat
+capacity in a systematic and comprehensive way. The analysis allows us to
+produce accurate anisotropic exchange coupling energies and unambiguously
+determine a crossover temperature ($\sim$25 K in the case of $NaYbSe2$), below
+which CEF effects fade away and pure spin-spin interactions stand out. We
+further validated the effective picture by successfully explaining the
+anomalous temperature dependence of electron spin resonance (ESR) spectral
+width. The effective scenario in principle can be generalized to other
+rare-earth spin systems with small CEF excitations.",2011.06274v2
+2021-08-18,"Charge Order and Fluctuations in Bi$_2$Sr$_{2-x}$La$_x$CuO$_{6+δ}$ Revealed by $^{63,65}$Cu-Nuclear Magnetic Resonance","The discovery of a magnetic-field-induced charge-density-wave (CDW) order in
+the pseudogap state via nuclear magnetic resonance (NMR) studies has
+highlighted the importance of ""charge"" in the physics of high
+transition-temperature ($T_{\rm c}$) superconductivity in copper oxides
+(cuprates). Herein, after briefly reviewing the progress achieved in the last
+few years, we report new results of $^{63,65}$Cu-NMR measurements on the CDW
+order and its fluctuation in the single-layered cuprate
+Bi$_2$Sr$_{2-x}$La$_x$CuO$_{6+\delta}$. The NMR spectrum under both in- and
+out-of-plane magnetic fields above $ H $ = 10 T indicates that the CDW replaces
+the antiferromagnetic order before superconductivity appears, but disappears
+before superconductivity is optimized. We found that the CDW onset temperature
+$T_{\rm CDW}$ scales with the pseudogap temperature $T^{\rm *}$. Comparison
+between $^{63}$Cu and $^{65}$Cu NMR indicates that the spin-lattice relaxation
+process is dominated by charge fluctuations in the doping regions where the CDW
+appears as well as at the pseudogap end point ($T^*$ = 0). These results
+suggest that charge orders and fluctuations exist in multiple doping regions
+and over a quite wide temperature range.",2108.08150v1
+2021-12-08,Manipulation of spin orientation via ferroelectric switching in Fe-doped Bi2WO6 from first principles,"Atomic-scale control of spins by electric fields is highly desirable for
+future technological applications. Magnetically-doped Aurivillius-phase oxides
+present one route to achieve this, with magnetic ions substituted into the
+ferroelectric structure at dilute concentrations, resulting in spin-charge
+coupling. However, there has been minimal exploration of the ferroelectric
+switching pathways in this materials class, limiting predictions of the
+influence of an electric field on the magnetic spins in the structure. Here, we
+determine the ferroelectric switching pathways of the end member of the
+Aurivilius phase family, Bi2WO6, using a combination of group theoretic
+analysis and density functional theory calculations. We find that in the ground
+state P21ab phase, a two-step switching pathway via C2 and Cm intermediate
+phases provides the lowest energy barrier. Considering iron substitutions on
+the W-site in Bi2WO6, we determine the spin easy axis. By tracking the change
+in spin directionality during ferroelectric switching, we find that a 90 degree
+switch in the polarization direction leads to a 112 degree reorientation of the
+spin easy axis. The low symmetry crystal-field environment of Bi2WO6 and
+magnetoelastic coupling on the magnetic dopant provide a route to spin control
+via and applied electric field.",2112.04055v1
+2022-01-21,Spin Hall magnetoresistance in paramagnetic NdGaO3,"In recent years, spin Hall magnetoresistance (SMR) has emerged as an
+efficient way to probe the spontaneous magnetization state in ordered magnetic
+systems, by electrical current. Less known is its versatility as a probe of
+materials that do not possess spontaneous magnetization such as in paramagnets.
+In this work, SMR is used to probe paramagnetic NdGaO3 (NGO), a rare earth
+oxide, possessing a sizable spin orbit interaction (L=6). NGO has not been
+investigated earlier for its efficiency in propagating spins. We have performed
+extensive temperature and angle dependent-magnetoresistance (ADMR) studies
+along dissimilar crystallographic axes in NGO, using platinum (Pt) as spin
+injector and detector and utilizing (inverse) spin Hall effect. We find a close
+correlation between the temperature dependence of the ADMR response with
+magnetization in NGO and a linear current bias dependence of the ADMR
+amplitudes. These are chacteristics of SMR effect in Pt/NGO, arising from the
+torque acting on localized moments in NGO and considering crystal field induced
+intermultiplet transitions with temperature. Control experiments on Pt/SrTiO3
+and Pt/SiO2 devices were also carried out in order to validate the observed SMR
+response in Pt/NGO bilayer and to rule out magnetoresistive contributions from
+Pt.",2201.08685v1
+2022-02-28,Strongly anisotropic electronic and magnetic structures in oxide dichlorides RuOCl$_2$ and OsOCl$_2$,"Here, using density functional theory and density matrix renormalization
+group methods, we investigate the electronic and magnetic properties of
+RuOCl$_2$ and OsOCl$_2$ with $d^4$ electronic configurations. Different from a
+previous study using VOI$_2$ with $d^1$ configuration, these systems with
+$4d^4$ or $5d^4$ do not exhibit a ferroelectric instability along the $a$-axis.
+Due to the fully-occupied $d_{xy}$ orbital in RuOCl$_2$ and OsOCl$_2$, the
+Peierls instability distortion disappears along the $b$-axis, leading to an
+undistorted I${\rm mmm}$ phase (No. 71). Furthermore, we observe strongly
+anisotropic electronic and magnetic structures along the $a$-axis. The large
+crystal-field splitting energy (between $d_{xz/yz}$ and $d_{xy}$ orbitals) and
+large hopping between nearest-neighbor Ru and Os atoms suppresses the
+spin-orbital effect in $M$OCl$_2$ ($M$ = Ru or Os) with electronic density $n =
+4$, resulting in a spin-1 system instead of a $J = 0$ singlet ground state.
+Moreover, we find staggered antiferromagnetic order with $\pi$ wavevector along
+the $M$-O chain direction ($a$-axis) while the magnetic coupling along the
+$b$-axis is weak. Based on Wannier functions from first-principles
+calculations, we calculated the relevant hopping amplitudes and crystal-field
+splitting energies of the $t_{2g}$ orbitals for the Os atoms to construct a
+multi-orbital Hubbard model for the $M$-O chains. Staggered AFM with
+$\uparrow$-$\downarrow$-$\uparrow$-$\downarrow$ spin structure dominates in our
+DMRG calculations, in agreement with DFT calculations.",2203.00060v2
+2022-05-08,Spin interaction and magnetism in cobaltate Kitaev candidate materials: an $ab$ $initio$ and model Hamiltonian approach,"In the quest for materials hosting Kitaev spin liquids, much of the efforts
+have been focused on the fourth- and fifth-row transition metal compounds,
+which are spin-orbit coupling assisted Mott insulators. Here, we study the
+structural and magnetic properties of 3$d$ transition metal oxides,
+Na$_2$Co$_2$TeO$_6$ and Na$_3$Co$_2$SbO$_6$. The partial occupancy of sodium in
+former compound is addressed using a cluster expansion, and a honeycomb lattice
+of sodiums is found to be energetically favored. Starting from the \textit{ab
+initio} band structures, a many-body second order perturbation theory leads to
+a pseudospin-$\frac{1}{2}$ Hamiltonian with estimated magnetic interactions. We
+show that the experimentally observed zigzag magnetic state is stabilized only
+when the first neighbor Kitaev coupling dominates over the Heisenberg term,
+both of which are highly suppressed due to presence of $e_g$ orbitals. A third
+neighbor Heisenberg interaction is found dominant in both these compounds. We
+also present a phase diagram for Na$_2$Co$_2$TeO$_6$ by varying the
+electron-electron and spin-orbit interactions. The computed spin excitation
+spectra are found to capture essential features of recent experimental magnon
+spectrum, lending support to our results.",2205.03836v2
+2022-10-17,"Long-range order, bosonic fluctuations, and pseudogap in strongly correlated electron systems","This thesis deals with the Hubbard model as prototypical model to describe
+the physics of electrons in the two-dimensional copper-oxide planes of
+high-$T_c$ cuprates. To get approximate solutions, we employ functional
+renormalization group (fRG) and dynamical mean-field theory (DMFT) methods.
+  We deal with the problem of identifying bosonic fluctuations in the vertex
+function, exhibiting an intricate dependence on momenta and frequencies already
+at moderate coupling. In the normal, paramagnetic phase, the goal is achieved
+by employing the recently introduced single-boson exchange decomposition. In
+the symmetry-broken phases, we reformulate the previously introduced
+combination of fRG with mean-field theory by explicitly introducing a bosonic
+field.
+  A widely discussed and challenging problem is the emergence of a pseudogap in
+the Hubbard model. In this thesis we assume this phase to be characterized by
+strong magnetic fluctuations. Following previous works, we fractionalize the
+electron in a chargon, carrying the electron's charge, and a charge neutral
+spinon, which represents local fluctuations of the spin orientation. The
+chargons undergo N\'eel or spiral magnetic order below a density-dependent
+transition temperature $T^*$. We compute DC charge transport coefficients for
+the chargons, and obtain a pronounced drop in the charge carrier density across
+the magnetic-to-paramagnetic transition. Directional fluctuations of the spin
+orientation are described by a non-linear sigma model and prevent long-range
+ordering of the electrons at any finite temperature. The phase where the
+chargon degrees of freedom are magnetically ordered shares many features with
+the pseudogap regime observed in high-$T_c$ cuprates: a strong reduction of the
+charge carrier density, a spin gap, Fermi arcs, and electronic nematicity.",2210.08889v1
+2022-10-17,"A comprehensive review on the ferroelectric orthochromates: Synthesis, property, and application","Multiferroics represent a class of advanced materials for promising
+applications and stand at the forefront of modern science for the special
+feature possessing both charge polar and magnetic order. Previous studies
+indicate that the family of RECrO3 (RE = rare earth) compounds is likely
+another rare candidate system holding both ferroelectricity and magnetism.
+However, many issues remain unsolved, casting hot disputes about whether RECrO3
+is multiferroic or not. For example, an incompatibility exists between reported
+structural models and observed ferroelectric behaviors, and it is not easy to
+determine the spin canting degree. To address these questions, one key step is
+to grow single crystals because they can provide more reliable information than
+other forms of matter do. In this review, the parent and doped ferroelectric
+YCrO3 compounds are comprehensively reviewed based on scientific and patent
+literatures from 1954 to 2022. The materials syntheses with different methods,
+including poly-, nano-, and single-crystalline samples and thin films, are
+summarized. The structural, magnetic, ferroelectric and dielectric, optical,
+and chemical-pressure (on Y and Cr sites by doping) dependent chemical and
+physical properties and the corresponding phase diagrams, are discussed.
+Diverse (potential) applications, including anti-corrosion, magnetohydrodynamic
+electrode, catalyst, negative-temperature-coefficient thermistor, magnetic
+refrigeration, protective coating, and solid oxide fuel cell, are present. To
+conclude, we summarize general results, reached consensuses, and existing
+controversies of the past nearly 69 years of intensive studies and highlight
+future research opportunities and emerging challenges to address existing
+issues.",2210.09170v1
+2023-04-13,"In situ theranostic platform uniting highly localized magnetic fluid hyperthermia, magnetic particle imaging, and thermometry in 3D","In all of medical profession a broad field of research is dedicated to seek
+less invasive and low-risk forms of therapy with the ultimate goal of
+non-invasive therapy, particularly in neoplasmic diseases. Theranostic
+platforms, combining diagnostic and therapeutic approaches within one system,
+have thus garnered interest to augment invasive surgical, chemical, and
+ionizing interventions. Magnetic particle imaging (MPI) offers, with its
+versatile tracer material (superparamagnetic iron oxide nanoparticles, SPIOs),
+a quite recent alternative to established radiation based diagnostic
+modalities. In addition, MPI lends a bimodal theranostic frame allowing to
+combine tomographic imaging with therapy techniques using the very same SPIOs.
+In this work, we show for the first time the interleaved combination of
+MPI-based imaging, therapy (highly localized magnetic fluid hyperthermia) and
+therapy safety control (MPI-based thermometry) within one theranostic platform
+in all three spatial dimensions.",2304.06554v2
+2023-04-23,Scanning SQUID-on-tip microscope in a top-loading cryogen-free dilution refrigerator,"The scanning superconducting quantum interference device (SQUID) fabricated
+on the tip of a sharp quartz pipette (SQUID-on-tip) has emerged as a versatile
+tool for nanoscale imaging of magnetic, thermal, and transport properties of
+microscopic devices of quantum materials. We present the design and performance
+of a scanning SQUID-on-tip microscope in a top-loading probe of a cryogen-free
+dilution refrigerator. The microscope is enclosed in a custom-made vacuum-tight
+cell mounted at the bottom of the probe and is suspended by springs to suppress
+vibrations caused by the pulse tube cryocooler. Two capillaries allow in-situ
+control of helium exchange gas pressure in the cell that is required for
+thermal imaging. A nanoscale heater is used to create local temperature
+gradients in the sample, which enables quantitative characterization of the
+relative vibrations between the tip and the sample. The spectrum of the
+vibrations shows distinct resonant peaks with maximal power density of about 27
+nm/Hz$^{1/2}$ in the in-plane direction. The performance of the SQUID-on-tip
+microscope is demonstrated by magnetic imaging of the MnBi$_2$Te$_4$ magnetic
+topological insulator, magnetization and current distribution imaging in a
+SrRuO$_3$ ferromagnetic oxide thin film, and by thermal imaging of dissipation
+in graphene.",2304.11667v1
+2024-01-10,Observation of correlation induced metal to half-metal phase transition and large orbital moment in $\mathrm{Sr_2CoO_4}$,"We present a detailed mean-field study to address the fundamental discrepancy
+in the ground state magnetization of $\mathrm{Sr_{2}CoO_{4}}$ (SCO). In
+contrast to the ferromagnetic metallic ground state obtained from density
+functional theory (DFT), DFT+$U$ gives three ferromagnetic solutions converging
+to integer moment values (1, 2 \& 3 $\mu_B$/f.u) over a range of $U$.
+Interestingly, two of the solutions are found to exhibit half-metallicity with
+correspondingly $S$=1/2 and S=3/2 spin states. The half-metallic ferromagnetic
+state with $S$=3/2 is found to be the ground state solution for SCO. Co atoms
+show a large deviation from the formal +4 oxidation state indicating the
+presence of strong covalency effects. Our results suggest a plausible metal to
+half-metal phase transition around $U$($J$)=4.4(1.16) eV. The Fermi surface
+study shows gradual collapse in states leading to half-metallicity suggesting
+\textit{\textbf{k}}-dependence of effective $U$ around the critical region.
+Surprisingly, in the presence of spin-orbit coupling (SOC), unexpectedly large
+orbital moment ($L_{z}$=0.6) is noted in SCO putting it among the class of 3$d$
+based transition metal compounds exhibiting pronounced orbital magnetization.
+The calculations give large magnetocrystalline anisotropy energy (MAE) of
+$\sim$48 meV. Large values of orbital magnetic moment contribution and MAE, in
+the presence of strong correlation effects, provide a better interpretation of
+experimental magnetization observed in SCO.",2401.05149v1
+2024-02-25,Superconducting stripes induced by ferromagnetic proximity in an oxide heterostructure,"The intimate connection between magnetism and superconducting pairing
+routinely plays a central role in determining the occurrence of unconventional
+superconducting states. In high-transition-temperature (high-Tc) stripe-ordered
+cuprate superconductors and a magnetically ordered iron-based superconductor,
+the coupling between magnetism and superconductivity gives birth to novel
+phases of matter with modulation of the superconducting pairing in the real
+space. Further exploration of these phases can shed light on the mechanism of
+unconventional superconductivity. Here we report on the discovery of a peculiar
+spatially-varying superconducting state residing at the interface between
+(110)-oriented KTaO3 and ferromagnetic EuO. Electrical transport measurements
+reveal different Tc and upper critical fields (Hc2) with current applied along
+the two orthogonal in-plane directions. Such anisotropy persistently occurs in
+the low-carrier-density samples that are characterized by strong coupling
+between Ta 5d and Eu 4f electrons, whereas in the high-carrier-density samples
+the coupling is weakened and Tc and Hc2 becomes isotropic. Complemented by
+local imaging of diamagnetism and theoretical analysis, our observations imply
+an unprecedented emergence of superconducting stripes wherein the phase
+coherence is established ahead of the rest of the interface, arising from a
+band-filling-dependent ferromagnetic proximity. The realization of such exotic
+superconducting states provides impetus for the study of novel physics in
+heterostructures possessing both magnetism and superconductivity.",2402.16022v1
+2024-03-13,Antiferromagnetic ordering and glassy nature in NASICON type NaFe$_2$PO$_4$(SO$_4$)$_2$,"We investigate crystal structure and magnetic properties including spin
+relaxation and magnetocaloric effect in NASICON type NaFe$_2$PO$_4$(SO$_4$)$_2$
+sample. The Rietveld refinement of x-ray and neutron diffraction patterns show
+a rhombohedral crystal structure with the R$\bar{3}$c space group. The
+core-level spectra confirm the desired oxidation state of constituent elements.
+The {\it dc}--magnetic susceptibility ($\chi$) behavior in zero field-cooled
+(ZFC) and field-cooled (FC) modes show the ordering temperature $\approx$50~K.
+Interestingly, the analysis of temperature dependent neutron diffraction
+patterns reveal an A-type antiferromagnetic (AFM) structure with the ordered
+moment of 3.8 $\mu_{B}$/Fe$^{3+}$ at 5~K, and a magnetostriction below $T_{\rm
+N}=$ 50~K. Further, the peak position in the {\it ac}--$\chi$ is found to be
+invariant with the excitation frequency supporting the notion of dominating AFM
+transition. Also, the unsaturated isothermal magnetization curve supports the
+AFM ordering of the moments; however, the observed coercivity suggests the
+presence of weak ferromagnetic (FM) correlations at 5~K. On the other hand, a
+clear bifurcation between ZFC and FC curves of {\it dc}--$\chi$ and the
+observed decrease in peak height of {\it ac}--$\chi$ with frequency suggest for
+the complex magnetic interactions. The spin relaxation behavior in
+thermo-remanent magnetization and aging measurements indicate the glassy states
+at 5~K. Moreover, the Arrott plots and magnetocaloric analysis reveal the
+AFM--FM interactions in the sample at lower temperatures.",2403.08679v1
+2020-07-14,High-resolution neutron imaging: a new approach to characterize water in anodic aluminum oxides,"During the growth of anodic Al oxide layers water incorporates in the film
+and therefore influences the intrinsic properties of the oxide formed. In this
+study, we propose a new approach, based on the use of high-resolution neutron
+imaging, to visualize and quantify the water content in porous Al oxides as a
+function of anodizing conditions. Water in these porous films is either
+incorporated directly in the oxide structure (structural) and/or fills the
+pores (morphological). This preliminary study demonstrates that the differences
+in water content of porous anodic Al oxide layers are strongly related to the
+oxide growth parameters but interestingly cannot be directly correlated to a
+specific change in the amorphous oxide structure or in the pore morphology. Due
+to the high sensitivity of high-resolution neutron imaging to small changes in
+the water content, we furthermore show that the morphological water content in
+Al oxides formed in sulfuric acid as well as in phosphoric acid is partially
+reversible upon heat treatment and immersion. High-resolution neutron imaging
+is also found to be highly sensitive to structural disorder and
+crystallographic orientations, allowing to identify different crystalline Al
+oxide samples based on their structural and morphological defect content. This
+offers new perspectives to study the effect of the hydrogen and/or water
+incorporation as well as oxide-related structural modifications on Al
+oxihydroxides in relation to growth parameters, stability, functionalization as
+well as properties tuning, highly relevant to surface protection and their use
+as templates.",2007.07118v1
+2014-03-18,"Film structure of epitaxial graphene oxide on SiC: Insight on the relationship between interlayer spacing, water content, and intralayer structure","Chemical oxidation of multilayer graphene grown on silicon carbide yields
+films exhibiting reproducible characteristics, lateral uniformity, smoothness
+over large areas, and manageable chemical complexity, thereby opening
+opportunities to accelerate both fundamental understanding and technological
+applications of this form of graphene oxide films. Here, we investigate the
+vertical inter-layer structure of these ultra-thin oxide films. X-ray
+diffraction, atomic force microscopy, and IR experiments show that the
+multilayer films exhibit excellent inter-layer registry, little amount (<10%)
+of intercalated water, and unexpectedly large interlayer separations of about
+9.35 {\AA}. Density functional theory calculations show that the apparent
+contradiction of ""little water but large interlayer spacing in the graphene
+oxide films"" can be explained by considering a multilayer film formed by carbon
+layers presenting, at the nanoscale, a non-homogenous oxidation, where
+non-oxidized and highly oxidized nano-domains coexist and where a few water
+molecules trapped between oxidized regions of the stacked layers are sufficient
+to account for the observed large inter-layer separations. This work sheds
+light on both the vertical and intra-layer structure of graphene oxide films
+grown on silicon carbide, and more in general, it provides novel insight on the
+relationship between inter-layer spacing, water content, and structure of
+graphene/graphite oxide materials.",1403.4633v1
+2016-11-22,Alpha-tocopherol inhibits pore formation in the oxidized bilayers,"In biological membranes, alpha-tocopherols ({\alpha}-toc; vitamin E) protect
+polyunsaturated lipids from free radicals. Although the interactions of
+{\alpha}-toc with non-oxidized lipid bilayers have been studied, their on
+oxidized bilayers remain unknown. In this study, atomistic molecular dynamics
+(MD) simulations of oxidized lipid bilayers were performed with varying
+concentrations of {\alpha}-toc. Bilayers with
+1-palmitoyl-2-lauroyl-sn-glycero-3-phosphocholine (PLPC) lipids and its
+aldehyde derivatives at 1:1 ratio were studied. Our simulations show that
+oxidized lipids self-assemble into aggregates with a water pore rapidly
+developing across the lipid bilayer. The free energy of transporting an
+{\alpha}-toc molecule in a lipid bilayer suggests that {\alpha}-tocs can
+passively adsorb into the bilayer. When {\alpha}-toc molecules were present at
+low concentrations in bilayers containing oxidized lipids, the formation of
+water pores was slowed down. At high {\alpha}-toc concentra-tions, no pores
+were observed. Based on the simulations, we propose that the mechanism of how
+{\alpha}-toc inhibits pore formation in bilayers with oxidized lipids is the
+follow-ing: {\alpha}-tocs trap the polar groups of the oxidized lipids at the
+membrane-water interface resulting in a decreased probability for the oxidized
+lipids to reach contact with the two leaflets and initiate pore formation. This
+demon-strates that {\alpha}-toc molecules not only protect the bilayer from
+oxidation but also help to stabilize the bilayer after lipid peroxidation
+occurs. These results will help in de-signing more efficient molecules to
+protect membranes from oxidative stress.",1611.07264v1
+2017-05-17,Visualizing the Cu and Cu2O Interface Transition in Nanoparticles with Environmental Scanning Transmission Electron Microscopy,"Understanding the oxidation and reduction mechanisms of catalytically active
+transition metal nanoparticles is important to improve their application in a
+variety of chemical processes. In nanocatalysis the nanoparticles can undergo
+oxidation or reduction in situ, and thus the redox species are not what are
+observed before and after reactions. We have used the novel environmental
+scanning transmission electron microscope (ESTEM) with 0.1 nm resolution in
+systematic studies of complex dynamic oxidation and reduction mechanisms of
+copper nanoparticles. The oxidation of copper has previously been reported to
+be dependent on its crystallography and its interaction with the substrate. By
+following the dynamic oxidation process in situ, in real time, with high-angle
+annular dark-field imaging in the ESTEM, we use conditions ideal to track the
+oxidation front as it progresses across a copper nanoparticle by following the
+changes in the atomic number (z) contrast with time. The oxidation occurs via
+the nucleation of the oxide phase (Cu2O) from one area of the nanoparticle
+which then progresses unidirectionally across the particle, with the Cu-to-Cu2O
+interface having a relationship of Cu{111} parallel to Cu2O{111}. The oxidation
+kinetics are related to the temperature and oxygen pressure. When the process
+is reversed in hydrogen, the reduction process is observed to be similar to the
+oxidation, with the same crystallographic relationship between the two phases.
+The dynamic observations provide unique insights into redox mechanisms which
+are important to understanding and controlling the oxidation and reduction of
+copper-based nanoparticles.",1705.06065v1
+2018-06-18,"Copper Doped Zinc Oxide Nanocrystalline Thin Film: Growth, Characterization, Effect of annealing on Photocatalytic activity and electrical properties of irradiated film","The problem of detecting the ability of some metal oxides as photocatalysts
+is receiving considerable attention in the world. The studied zinc oxide is
+considered as one of the most utilized semiconductors, due to its direct band
+gap of 3.37 eV and a large exciton binding energy of 60 meV at room
+temperature. The characteristic formulation of Copper doped zinc oxide is
+implemented to obtain an improved adsorption kinetics and photocatalytic
+activity of zinc oxide photocatalyst capable of evolving estimated
+photoluminescence (PL) spectra of zinc oxide nanoparticles to explore the
+effect of Copper doping and annealing temperature on its optical properties.
+using Solgel spin coating technique, Zinc oxide and copper doped zinc oxide
+thin films were deposited on borosilicate substrate and all films was annealed
+at 500 C for 5- hours. Optical properties of the films have been studied using
+spectrophotometer in the wavelength range 300-800nm and structure of zinc oxide
+films is investigated and included reported, also the effect of the doping
+concentration of Copper. Further the characteristic formulation to treat the
+photocatalytic performance of pure zinc oxide and Copper Doped zinc oxide
+samples were investigated through the degradation of Malachite Green (MG), as a
+model of organic pollutants, under UV light irradiation. Mainly, these films
+exhibited a good transparency in the visible region. It was observed that when
+the doping concentration increased, the transmittance also increased.
+irradiation for different times.",1806.06494v1
+2022-07-06,Detecting chiral asymmetry in the interstellar medium using propylene-oxide,"(Abridged) Life is distinctly homochiral. The origins of this homochirality
+are under active debate. Recently, propylene-oxide has been detected in the
+gas-phase interstellar medium (ISM) (McGuire et al. 2016). The enantiomeric
+composition of ISM propylene-oxide may be probed through circular polarization
+measurements, but accurate estimates of the circular dichroism properties of
+the microwave transitions of propylene-oxide are not available. We develop a
+model of the circular dichroic activity in torsion-rotation transitions of
+closed-shell chiral molecules, such as propylene-oxide. With this model, we
+estimate the viability, and optimize observation strategies, of enantiomeric
+excess detection in ISM propylene-oxide. We present estimates for the dichroic
+activity of the torsion-rotation transitions of propylene-oxide, where we
+predict that the circular polarization fractions of emission lines of
+enantiopure propylene-oxide relevant to astronomical detection of
+propylene-oxide are on the order of 10^(-6). Due to the low predicted circular
+polarization fractions, we conclude that enantiomeric characterization of
+propylene-oxide in the gas phase of the ISM is impossible with current
+astronomical observation techniques. We suggest that only chiral radical
+species may be viably employed for enantiomeric excess detection. We estimate
+that laboratory experiments may be successful in detecting the enantiomeric
+composition of a mixture of propylene-oxide through microwave dichroism
+spectroscopy. The theory we present in this paper provides a solid theoretical
+underpinning for such laboratory circular dichroism measurements in microwave
+transitions.",2207.02888v1
+2023-08-10,Predictions and correlation analyses of Ellingham diagrams in binary oxides,"Knowing oxide-forming ability is vital to gain desired or avoid deleterious
+oxides formation through tuning oxidizing environment and materials chemistry.
+Here, we have conducted a comprehensive thermodynamic analysis of 137 binary
+oxides using the presently predicted Ellingham diagrams. It is found that the
+active elements to form oxides easily are the f-block elements (lanthanides and
+actinides), elements in the groups II, III, and IV (alkaline earth, Sc, Y, Ti,
+Zr, and Hf), and Al and Li; while the noble elements with their oxides
+nonstable and easily reduced are coinage metals (Cu, Ag, and especially Au),
+Pt-group elements, and Hg and Se. Machine learning based sequential feature
+selection indicates that oxide-forming ability can be represented by electronic
+structures of pure elements, for example, their d- and s-valence electrons,
+Mendeleev numbers, and the groups, making the periodic table a useful tool to
+tailor oxide-forming ability. The other key elemental features to correlate
+oxide-forming ability are thermochemical properties such as melting points and
+standard entropy at 298 K of pure elements. It further shows that the present
+Ellingham diagrams enable qualitatively understanding and even predicting
+oxides formed in multicomponent materials, such as the Fe-20Cr-20Ni alloy (in
+wt.%) and the equimolar high entropy alloy of AlCoCrFeNi, which are in
+accordance with thermodynamic calculations using the CALPHAD approach and
+experimental observations in the literature.",2308.05837v1
+2020-07-30,The effect of structural and magnetic disorder on the 3$d$-5$d$ exchange interactions of La$_{2-x}$Ca$_{x}$CoIrO$_{6}$,"The delicate balance between spin-orbit coupling, Coulomb repulsion and
+crystalline electric field interactions observed in Ir-based oxides is usually
+manifested as exotic magnetic behavior. Here we investigate the evolution of
+the exchange coupling between Co and Ir for partial La substitution by Ca in
+La$_{2}$CoIrO$_6$. A great advantage of the use of Ca$^{2+}$ as replacement for
+La$^{3+}$ is the similarity of its ionic radii. Thus, the observed magnetic
+changes can more easily be associated to electronic variations. A thorough
+investigation of the structural, electronic and magnetic properties of the
+La$_{2-x}$Ca$_{x}$CoIrO$_6$ system was carried out by means of synchrotron
+x-ray powder diffraction, muon spin rotation and relaxation ($\mu$SR), AC and
+DC magnetization, XAS, XMCD, Raman spectroscopy, electrical resistivity and
+dielectric permittivity. Our XAS results show that up to 25% of Ca substitution
+at the La site results in the emergence of Co$^{3+}$, possibly in high spin
+state, while the introduction of larger amount of Ca leads to the increase of
+Ir valence. The competing magnetic interactions resulting from the mixed
+valences lead to a coexistence of a magnetically ordered and an emerging spin
+glass (SG) state for the doped samples. Our $\mu$SR results indicate that for
+La$_{2}$CoIrO$_6$ a nearly constant fraction of a paramagnetic (PM) phase
+persists down to low temperature, possibly related to the presence of a small
+amount of Ir$^{3+}$ and to the anti-site disorder at Co/Ir sites. For the doped
+compounds the PM phase freezes below 30 K, but there is still some dynamics
+associated with the SG. The dielectric data obtained for the parent compound
+and the one with 25% of Ca-doping indicate a possible magnetodielectric effect,
+which is discussed in terms of the electron hopping between the TM ions, the
+anti-site disorder and the distorted crystalline structure.",2007.15318v1
+2018-05-31,Hydrogen Decrepitation and Spark Plasma Sintering to Produce Recycled SmCo5 Magnets With High Coercivity,"Spark plasma sintering (SPS) technique is applied in combination with
+hydrogen decrepitation process for the recycling of SmCo5 magnets. The SmCo5
+magnets for recycling were first decrepitated by hydrogen gas of a pressure of
+4 bar for 3 hours to produce decrepitated powder. This powder was then used to
+prepare isotropic sintered magnets using the SPS technique, by sintering at
+800-1000 oC for 1 minute. Full densification of the SPS-ed magnets was possible
+at a temperature of 1000 oC. The sample sintered at 900 oC showed the best
+internal coercivity (jHc) of higher than 1500 kA/m with high remanence (Br)
+value of 0.47 T and energy product (BH(max)) of 43.4 kJ/m3. The properties of
+the SPS-ed sample sintered at 900 oC were compared with conventionally sintered
+(CVS-ed) sample prepared by using fresh SmCo5 powder. The results showed the
+improvement of the magnetic properties of the SPS-ed sample in comparison to
+the CVS-ed sample at room temperature, and the possibility to use the SPS-ed
+sample at high temperature of 180 oC, where the sample showed good magnetic
+properties of jHc of 1502 kA/m, Br of 0.44 T and BH(max) of 36.4 kJ/m3. The
+microstructure and X-ray diffraction patterns of the SPS-ed and the CVS-ed
+samples were studied; where the samples showed to basically consist of SmCo5
+matrix phase with Sm2Co7 and Sm-oxides.",1805.12347v1
+2020-12-16,Observation of anti-damping spin-orbit torques generated by in-plane and out-of-plane spin polarizations in MnPd3,"High spin-orbit torques (SOTs) generated by topological materials and heavy
+metals interfaced with a ferromagnetic layer show promise for next generation
+magnetic memory and logic devices. SOTs generated from the in-plane spin
+polarization along y-axis originated by the spin Hall and Edelstein effects can
+switch magnetization collinear with the spin polarization in the absence of
+external magnetic fields. However, an external magnetic field is required to
+switch the magnetization along x and z-axes via SOT generated by y-spin
+polarization. Here, we present that the above limitation can be circumvented by
+unconventional SOT in magnetron-sputtered thin film MnPd3. In addition to the
+conventional in-plane anti-damping-like torque due to the y-spin polarization,
+out-of-plane and in-plane anti-damping-like torques originating from z-spin and
+x-spin polarizations, respectively have been observed at room temperature. The
+spin torque efficiency corresponding to the y-spin polarization from MnPd3 thin
+films grown on thermally oxidized silicon substrate and post annealed at 400
+Deg C is 0.34 - 0.44. Remarkably, we have demonstrated complete external
+magnetic field-free switching of perpendicular Co layer via unconventional
+out-of-plane anti-damping-like torque from z-spin polarization. Based on the
+density functional theory calculations, we determine that the observed x- and
+z- spin polarizations with the in-plane charge current are due to the low
+symmetry of the (114) oriented MnPd3 thin films. Taken together, the new
+material reported here provides a path to realize a practical spin channel in
+ultrafast magnetic memory and logic devices.",2012.09315v1
+2021-09-03,Anomalous magnetic exchange in a dimerized quantum-magnet composed of unlike spin species,"We present here a study of the magnetic properties of the antiferromagnetic
+dimer material CuVOF$_4$(H$_2$O)$_6\cdot$H$_2$O, in which the dimer unit is
+composed of two different $S = 1/2$ species, Cu(II) and V(IV). An applied
+magnetic field of $\mu_0H_{\rm c1} = 13.1(1)~\rm T$ is found to close the
+singlet-triplet energy gap, the magnitude of which is governed by the
+antiferromagnetic intradimer, $J_0 \approx 21~\rm K$, and interdimer, $J'
+\approx 1~\rm K$, exchange energies, determined from magnetometry and
+electron-spin resonance measurements. The results of density functional theory
+(DFT) calculations are consistent with the experimental results and predicts
+antiferromagnetic coupling along all nearest-neighbor bonds, with the magnetic
+ground state comprising spins of different species aligning antiparallel to one
+another, while spins of the same species are aligned parallel. The magnetism in
+this system cannot be accurately described by the overlap between localized V
+orbitals and magnetic Cu orbitals lying in the Jahn-Teller (JT) plane, with a
+tight-binding model based on such a set of orbitals incorrectly predicting that
+interdimer exchange should be dominant. DFT calculations indicate significant
+spin density on the bridging oxide, suggesting instead an unusual mechanism in
+which intradimer exchange is mediated through the O atom on the Cu(II) JT axis.",2109.01529v2
+2023-08-05,$μ$SR Study of the Dipole-Octupole Quantum Spin Ice Candidate Ce$_2$Zr$_2$O$_7$,"The Ce$^{3+}$ pseudospin-1/2 degrees of freedom in Ce$_2$Zr$_2$O$_7$ possess
+both dipolar and octupolar character which enables the possibility of novel
+quantum spin liquid ground states in this material. Here we report new muon
+spin relaxation and rotation ($\mu$SR) measurements on single crystal samples
+of Ce$_2$Zr$_2$O$_7$ in zero magnetic field and in magnetic fields directed
+along the $[1,\bar{1},0]$ and $[1,1,1]$ crystallographic directions, and for
+magnetic fields directed both longitudinal and transverse to the direction of
+muon polarization. Our zero-field results show no signs of magnetic ordering or
+spin freezing, consistent with earlier zero-field $\mu$SR measurements on a
+powder sample of Ce$_2$Zr$_2$O$_7$, and also with the expectations for a
+quantum spin ice. However, we measure a more gentle relaxation rate for
+Ce$_2$Zr$_2$O$_7$ in zero-field at low temperatures than was previously
+reported. This difference in relaxation rate is likely due to the low
+oxidation, and correspondingly, the high stoichiometry of our single crystal
+samples. Longitudinal field measurements confirm that the magnetic dipole
+moments in Ce$_2$Zr$_2$O$_7$ remain dynamic at $T = 0.1$ $\mathrm{K}$. For both
+$[1,\bar{1},0]$ and $[1,1,1]$ magnetic fields, our $\mu$SR Knight shift
+measurements show a field-induced leveling off of the magnetic susceptibility
+at low temperature which is qualitatively consistent with corresponding
+calculations using the numerical-linked-cluster method in combination with
+recent estimates for the nearest-neighbour exchange parameters of
+Ce$_2$Zr$_2$O$_7$.",2308.02800v3
+2013-10-25,Quantum magnons of the intermediate phase of half-doped manganite oxides,"At half doping, the ground state of three-dimensional manganite perovskite
+oxides like R$_{1-x}$Ca$_x$MnO$_3$, where R is a trivalent ion such as La, Pr,
+etc, is still unclear. Many experimental findings agree better with the
+combined magnetic, charge, and orbital order characteristic of the
+""intermediate phase"", introduced by Efremov et al. in 2004 [Nature Mats. 3,
+853]. This phase consists of spin dimers (thus incorporating aspects of the
+Zener polaron phase (ZP) proposed in 2002 by Daoud-Aladine et al. [Phys. Rev.
+Lett. 89, 097205]), though formed by a pair of parallel Mn spins of different
+magnitude, in principle (thereby allowing for a degree of Mn charge
+disproportionation: not necessarily as large as that of Mn$^{3+}$-Mn$^{4+}$ in
+Goodenough's original CE phase [Phys. Rev. 100, 564 (1955)]). In the
+intermediate phase, consecutive spin dimers localed along the planar zig-zag
+chains are oriented at a constant relative angle $\Phi$ between them. Varying
+Mn-charge disproportionation and $\Phi$, the intermediate phase should allow to
+continuously interpolate between the two limiting cases of the CE phase and the
+dimer phase denoted as ""orthogonal intermediate $\pi/2-$phase"". It is not easy
+to find a microscopic model able to describe the phenomenological intermediate
+phase adequately for the spin, charge, and orbital degrees of freedom
+simultaneously. Here, we study the quantum spin excitations of a planar model
+of interacting localized spins, which we found can stabilize the intermediate
+phase classically. We compare the quantum magnons of the intermediate phase
+with those of the CE and orthogonal $\pi/2$ phases, in the context of recent
+experimental results.",1310.6954v1
+2015-06-16,Evidence of quantum dimer excitations in Sr$_3$Ir$_2$O$_7$,"The magnetic excitation spectrum in the bilayer iridate Sr$_3$Ir$_2$O$_7$ has
+been investigated using high-resolution resonant inelastic x-ray scattering
+(RIXS) performed at the iridium L$_3$ edge and theoretical techniques. A study
+of the systematic dependence of the RIXS spectrum on the orientation of the
+wavevector transfer, $\mathbf{Q}$, with respect to the iridium-oxide bilayer
+has revealed that the magnon dispersion is comprised of two branches well
+separated in energy and gapped across the entire Brillouin zone. Our results
+contrast with those of an earlier study which reported the existence of a
+single dominant branch. While these earlier results were interpreted as two
+overlapping modes within a spin-wave model of weakly coupled iridium-oxide
+planes, our results are more reminiscent of those expected for a system of
+weakly coupled dimers. In this latter approach the lower and higher energy
+modes find a natural explanation as those corresponding to transverse and
+longitudinal fluctuations, respectively. We have therefore developed a
+bond-operator theory which describes the magnetic dispersion in
+Sr$_3$Ir$_2$O$_7$ in terms of quantum dimer excitations. In our model
+dimerisation is produced by the leading Heisenberg exchange, $J_c$, which
+couples iridium ions in adjacent planes of the bilayer. The Hamiltonian also
+includes in plane exchange, $J$, as well as further neighbour couplings and
+relevant anisotropies. The bond-operator theory provides an excellent account
+of the dispersion of both modes, while the measured $\mathbf{Q}$ dependence of
+the RIXS intensities is in reasonable qualitative accord with the spin-spin
+correlation function calculated from the theory. We discuss our results in the
+context of the quantum criticality of bilayer dimer systems in the presence of
+anisotropic interactions derived from strong spin-orbit coupling.",1506.04877v1
+2016-04-18,The High Temperature Superconductivity in Cuprates: Physics of the Pseudogap Region,"We discuss the physics of the high temperature superconductivity in hole
+doped copper oxide ceramics in the pseudogap region. Starting from an effective
+reduced Hamiltonian relevant to the dynamics of holes injected into the copper
+oxide layers proposed in a previous paper, we determine the superconductive
+condensate wavefunction. We show that the low-lying elementary condensate
+excitations are analogous to the rotons in superfluid $^4He$. We argue that the
+rotons-like excitations account for the specific heat anomaly at the critical
+temperature. We discuss and compare with experimental observations the London
+penetration length, the Abrikosov vortices, the upper and lower critical
+magnetic fields, and the critical current density. We give arguments to explain
+the origin of the Fermi arcs and Fermi pockets. We investigate the nodal gap in
+the cuprate superconductors and discuss both the doping and temperature
+dependence of the nodal gap. We suggest that the nodal gap is responsible for
+the doping dependence of the so-called nodal Fermi velocity detected in angle
+resolved photoemission spectroscopy studies. We discuss the thermodynamics of
+the nodal quasielectron liquid and their role in the low temperature specific
+heat. We propose that the ubiquitous presence of charge density wave in hole
+doped cuprate superconductors in the pseudogap region originates from
+instabilities of the nodal quasielectrons driven by the interaction with the
+planar $CuO_2$ lattice. We investigate the doping dependence of the charge
+density wave gap and the competition between charge order and
+superconductivity. We discuss the effects of external magnetic fields on the
+charge density wave gap and elucidate the interplay between charge density wave
+and Abrikosov vortices. Finally, we examine the physics underlying quantum
+oscillations in the pseudogap region.",1604.05059v3
+2018-04-05,"Spin-orbit coupled systems in the ""atomic"" limit: rhenates, osmates, iridates","Motivated by RIXS experiments on a wide range of complex heavy oxides,
+including rhenates, osmates, and iridates, we discuss the theory of RIXS for
+site-localized $t_{2g}$ orbital systems with strong spin-orbit coupling. For
+such systems, we present exact diagonalization results for the spectrum at
+different electron fillings, showing that it accesses ""single-particle"" and
+""multi-particle"" excitations. This leads to a simple picture for the energies
+and intensities of the RIXS spectra in Mott insulators such as double
+perovskites which feature highly localized electrons, and yields estimates of
+the spin-orbit coupling and Hund's coupling in correlated $5d$ oxides. We
+present new higher resolution RIXS data at the Re-L$_3$ edge in Ba$_2$YReO$_6$
+which finds a previously unresolved peak splitting, providing further
+confirmation of our theoretical predictions. Using ab initio electronic
+structure calculations on Ba$_2$${\cal M}$ReO$_6$ (with ${\cal M}$=Re, Os, Ir)
+we show that while the atomic limit yields a reasonable effective Hamiltonian
+description of the experimental observations, effects such as $t_{2g}$-$e_g$
+interactions and hybridization with oxygen are important. Our ab initio
+estimate for the strength of the intersite exchange coupling shows that,
+compared to the osmates, the exchange is one or two orders of magnitude weaker
+in the rhenates and iridates, which may partly explain the suppression of
+long-range magnetic order in the latter compounds. As a way to interpolate
+between the site-localized picture and our electronic structure band
+calculations, we discuss the spin-orbital levels of the ${\cal M}$O$_6$
+cluster. This suggests a possible role for non-dispersive intra-cluster
+excitons in Ba$_2$YIrO$_6$ which may lead to a weak breakdown of the atomic
+$J_{\rm eff}=0$ picture and to small magnetic moments.",1804.02006v2
+2014-06-19,AC loss and coupling currents in YBCO coated conductors with varying number of filaments,"Striation of HTS coated conductors (CCs) as a way to reduce their
+magnetization AC losses has been the subject of intense research in the past
+years by several groups. While the principle of this approach is well
+understood, its practical application on commercial material to be used in
+power application is still far to be implemented due to manufacturing and
+technological constraints. Recent advances in tape quality and striation
+technology are now enabling systematic investigations of the influence of the
+number of filaments on AC loss reduction with a consistency that was not
+available in the past. In this work we demonstrate the technological
+feasibility of reducing the magnetization losses of commercially available CC
+by striating them into a high number of filaments (up to 120). The loss
+reduction exceeds one order of magnitude and does not come at the expense of
+current-carrying capability: samples with 10 and 20 filaments are unaffected by
+the striation process, while samples with 80 and 120 filaments still retain 80
+and 70% of the current-carrying potential, respectively. We also investigate
+the transverse resistivity in order to understand the paths followed by the
+coupling currents: we found that the coupling current prevalently flows in the
+metallic substrate, rather than in and out of the filaments. Finally, we use
+oxidation as a method to reduce the coupling currents and losses. The
+contribution of this work is three-fold: 1) It describes the know-how to
+produce a large number of high quality striations in commercially available
+CCs, greatly reducing their losses without extensively degrading their
+transport properties; 2) It provides a comprehensive characterization of said
+samples (e.g. measurements in a wide frequency range, transverse resistance
+profiles, influence of oxidation on DC and AC behavior); 3) It provides new
+insight on the patterns of the coupling currents.",1406.4990v2
+2018-12-17,Electron spin relaxation of single phosphorus donors in metal-oxide-semiconductor nanoscale devices,"We analyze the electron spin relaxation rate $1/T_1$ of individual
+ion-implanted $^{31}$P donors, in a large set of metal-oxide-semiconductor
+(MOS) silicon nanoscale devices, with the aim of identifying spin relaxation
+mechanisms peculiar to the environment of the spins. The measurements are
+conducted at low temperatures ($T\approx 100$~mK), as a function of external
+magnetic field $B_0$ and donor electrochemical potential $\mu_{\rm D}$. We
+observe a magnetic field dependence of the form $1/T_1\propto B_0^5$ for
+$B_0\gtrsim 3\,$ T, corresponding to the phonon-induced relaxation typical of
+donors in the bulk. However, the relaxation rate varies by up to two orders of
+magnitude between different devices. We attribute these differences to
+variations in lattice strain at the location of the donor. For $B_0\lesssim
+3\,$T, the relaxation rate changes to $1/T_1\propto B_0$ for two devices. This
+is consistent with relaxation induced by evanescent-wave Johnson noise created
+by the metal structures fabricated above the donors. At such low fields, where
+$T_1>1\,$s, we also observe and quantify the spurious increase of $1/T_1$ when
+the electrochemical potential of the spin excited state $|\uparrow\rangle$
+comes in proximity to empty states in the charge reservoir, leading to
+spin-dependent tunneling that resets the spin to $|\downarrow\rangle$. These
+results give precious insights into the microscopic phenomena that affect spin
+relaxation in MOS nanoscale devices, and provide strategies for engineering
+spin qubits with improved spin lifetimes.",1812.06644v2
+2019-03-01,Coexistence of metallic and nonmetallic properties in the pyrochlore Lu$_2$Rh$_2$O$_7$,"Transition metal oxides of the $4d$ and $5d$ block have recently become the
+targets of materials discovery, largely due to their strong spin-orbit coupling
+that can generate exotic magnetic and electronic states. Here we report the
+high pressure synthesis of Lu$_2$Rh$_2$O$_7$, a new cubic pyrochlore oxide
+based on $4d^5$ Rh$^{4+}$ and characterizations via thermodynamic, electrical
+transport, and muon spin relaxation measurements. Magnetic susceptibility
+measurements reveal a large temperature-independent Pauli paramagnetic
+contribution, while heat capacity shows an enhanced Sommerfeld coefficient,
+$\gamma$ = 21.8(1) mJ/mol-Rh K$^2$. Muon spin relaxation measurements confirm
+that Lu$_2$Rh$_2$O$_7$ remains paramagnetic down to 2 K. Taken in combination,
+these three measurements suggest that Lu$_2$Rh$_2$O$_7$ is a correlated
+paramagnetic metal with a Wilson ratio of $R_W = 2.5$. However, electric
+transport measurements present a striking contradiction as the resistivity of
+Lu$_2$Rh$_2$O$_7$ is observed to monotonically increase with decreasing
+temperature, indicative of a nonmetallic state. Furthermore, although the
+magnitude of the resistivity is that of a semiconductor, the temperature
+dependence does not obey any conventional form. Thus, we propose that
+Lu$_2$Rh$_2$O$_7$ may belong to the same novel class of non-Fermi liquids as
+the nonmetallic metal FeCrAs.",1903.00399v1
+2019-12-10,Sign-tunable anomalous Hall effect induced by two-dimensional symmetry-protected nodal structures in ferromagnetic perovskite oxide thin films,"Magnetism and spin-orbit coupling (SOC) are two quintessential ingredients
+underlying novel topological transport phenomena in itinerant ferromagnets.
+When spin-polarized bands support nodal points/lines with band degeneracy that
+can be lifted by SOC, the nodal structures become a source of Berry curvature;
+this leads to a large anomalous Hall effect (AHE). Contrary to
+three-dimensional systems that naturally host nodal points/lines,
+two-dimensional (2D) systems can possess stable nodal structures only when
+proper crystalline symmetry exists. Here we show that 2D spin-polarized band
+structures of perovskite oxides generally support symmetry-protected nodal
+lines and points that govern both the sign and the magnitude of the AHE. To
+demonstrate this, we performed angle-resolved photoemission studies of
+ultrathin films of SrRuO$_3$, a representative metallic ferromagnet with SOC.
+We show that the sign-changing AHE upon variation in the film thickness,
+magnetization, and chemical potential can be well explained by theoretical
+models. Our study is the first to directly characterize the topological band
+structure of 2D spin-polarized bands and the corresponding AHE, which could
+facilitate new switchable devices based on ferromagnetic ultrathin films.",1912.04757v2
+2021-10-05,Slow oxidation of magnetite nanoparticles elucidates the limits of the Verwey transition,"Magnetite (Fe3O4) is of fundamental importance as the original magnetic
+material and also for the Verwey transition near T_V = 125 K, below which a
+complex lattice distortion and electron orders occur. The Verwey transition is
+suppressed by strain or chemical doping effects giving rise to well-documented
+first and second-order regimes, but the origin of the order change is unclear.
+Here, we show that slow oxidation of monodisperse Fe3O4 nanoparticles leads to
+an intriguing variation of the Verwey transition that elucidates the doping
+effects. Exposure to various fixed oxygen pressures at ambient temperature
+leads to an initial drop to TV minima as low as 70 K after 45-75 days, followed
+by recovery to a constant value of 95 K after 160 days that persists in all
+experiments for aging times up to 1070 days. A physical model based on both
+doping and doping-gradient effects accounts quantitatively for this evolution
+and demonstrates that the persistent 95 K value corresponds to the lower limit
+for homogenously doped magnetite and hence for the first order regime. In
+comparison, further suppression down to 70 K results from inhomogeneous strains
+that characterize the second-order region. This work demonstrates that slow
+reactions of nanoparticles can give exquisite control and separation of
+homogenous and inhomogeneous doping or strain effects on an nm scale and offers
+opportunities for similar insights into complex electronic and magnetic phase
+transitions in other materials.",2110.01817v1
+2021-12-15,Magnetic field robust high quality factor NbTiN superconducting microwave resonators,"We systematically study the performance of compact lumped element planar
+microwave $\mathrm{Nb_{70}Ti_{30}N}$ (NbTiN) resonators operating at 5 GHz in
+external in-plane magnetic fields up to 440 mT, a broad temperature regime from
+2.2 K up to 13 K, as well as mK temperatures. For comparison, the resonators
+have been fabricated on thermally oxidized and pristine, (001) oriented silicon
+substrates. When operating the resonators in the multi-photon regime at $T=2.2$
+K, we find internal quality factors $Q_{\mathrm{int}}\simeq$ $2\cdot10^5$ for
+NbTiN resonators grown on pristine Si substrates, while resonators grown on
+thermally oxidized substrates show a reduced value of $Q_{\mathrm{int}}\simeq$
+$1\cdot10^4$, providing evidence for additional loss channels for the latter
+substrate. In addition, we investigate the $Q$-factors of the resonators on
+pristine Si substrates at millikelvin temperatures to asses their applicability
+for quantum applications. We find $Q_{\mathrm{int}}\simeq$ $2\cdot10^5$ in the
+single photon regime and $Q_{\mathrm{int}}\simeq$ $5\cdot10^5$ in the high
+power regime at $T=7$ mK.",2112.08296v1
+2022-01-17,Tailoring Mie Resonances in Cupric Oxide Particles for Use as Nanoantennas,"The field of nano-optics has grown with plasmonic metals. Metals such as
+silver, gold, and copper nanoparticles, can concentrate electromagnetic (EM)
+fields at the nanoscale, due to the special property called localized surface
+plasmon resonance (LSPR). This laid the foundation for a wide range of
+applications, including nanoscale optics, solar energy harvesting,
+photocatalysis, and biosensing. However, there are inherent problems associated
+with plasmonic metals, such as high heating losses, and their inability to be
+scaled-up like semiconductor fabrication processes. In addition, the field
+enhancement is restricted only to electric fields. All together these inhibit
+the broader use of PMNs in practical applications. In this work, we report
+submicron cupric oxide (CuO) particles with a medium refractive index that can
+exhibit strong electric and magnetic Mie resonances with strong
+extinction/scattering cross-sections comparable to or slightly exceeding those
+of their plasmonic counterparts. Through the development of particle synthesis
+techniques with strong shape and size control, optical spectroscopy, and
+finite-difference-time-domain simulations we show that the Mie resonance peak
+wavelengths are size- and shape-dependent. This gives tunability in the visible
+to near-infrared regions for harvesting a wider fraction of the solar spectrum.
+Therefore, submicron CuO particles exhibit strong potential in emerging as
+high-performance alternatives to PMNs. The strong electric and magnetic
+Mie-resonance-mediated nanoantenna effect attribute that CuO particles can be
+potentially used in a plethora of applications, including surface-enhance Raman
+spectroscopy, metamaterials, photocatalysis, and photovoltaics.",2201.06608v1
+2024-01-16,Controlled synthesis and characterization of porous silicon nanoparticles for dynamic nuclear polarization,"Si nanoparticles (NPs) have been actively developed as a hyperpolarized
+magnetic resonance imaging (MRI) agent with an imaging window of more than one
+hour. However, the progress in the development of NPs has been hampered by the
+incomplete understanding of their structural properties that correspond to
+efficient hyperpolarization build up and long polarization decays. In this work
+we study dynamic nuclear polarization (DNP) of single crystal porous Si (PSi)
+NPs with defined doping densities ranging from nominally undoped to highly
+doped with boron or phosphorus. To develop such PSi NPs we perform low-load
+metal-assisted catalytic etching for electronic grade Si powder followed by
+thermal oxidation to form the dangling bonds in the $\text{Si/SiO}_2$
+interface, the $P_b$ centers, which are the endogenous source of the unpaired
+electron spins necessary for DNP. The controlled fabrication and oxidation
+procedures allow us to thoroughly investigate the impact of the magnetic field,
+temperature and doping on the DNP process, as well as to identify the rate
+limiting step for the polarization buildup and decay. We argue that the buildup
+and decay rate constants are limited by the polarization transfer across the
+nuclear spin diffusion barrier determined by the large hyperfine shift of the
+central \textsuperscript{29}Si nuclei of the $P_b$ centers. Finally, we find
+the room temperature relaxation of low boron doped PSi NPs reaching $75 \pm 3$
+minutes and nuclear polarization levels exceeding $\sim 6$ % when polarized at
+6.7 T and 1.4 K. Our study thus establishes solid grounds for further
+development of Si NPs.",2401.08320v1
+2006-04-11,Superconductor made by electrolyzed and oxidized water,"By deintercalation of Na+ followed by inserting bilayers of water molecules
+into the host lattice, the layered cobalt oxide of gamma-Na0.7CoO2 undergoes a
+topotactic transformation to a layered cobalt oxyhydrate of
+Na0.35(H2O)1.3CoO2-delta with the c-axis expanded from c = 10.9 anstrom to c =
+19.6 anstrom. In this paper, we demonstrate that the superconducting phase of c
+= 19.6 anstrom can be directly obtained by simply immersing gamma-Na0.7CoO2
+powders in electrolyzed/oxidized (EO) water, which is readily available from a
+commercial electrolyzed water generator. We found that high oxidation-reduction
+potential of EO water drives the oxidation of the cobalt ions accompanying by
+the formation of the superconductive c = 19.6 anstrom phase. Our results
+demonstrate how EO water can be used to oxidize the cobalt ions and hence form
+superconducting cobalt oxyhydrates in a clean and simple way and may provide an
+economic and environment-friendly route to oxidize the transition metal of
+complex metal oxides",0604264v1
+2007-01-31,CO oxidation at Pd(100): A first-principles constrained thermodynamics study,"The possible formation of oxides or thin oxide films (surface oxides) on late
+transition metal surfaces is recently being recognized as an essential
+ingredient when aiming to understand catalytic oxidation reactions under
+technologically relevant gas phase conditions. Using the CO oxidation at
+Pd(100) as example, we investigate the composition and structure of this model
+catalyst surface over a wide range of (T,p)-conditions within a multiscale
+modeling approach where density-functional theory is linked to thermodynamics.
+The results show that under the catalytically most relevant gas phase
+conditions a thin surface oxide is the most stable ""phase"" and that the system
+is actually very close to a transition between this oxidic state and a reduced
+state in form of a CO covered Pd(100) surface.",0701777v1
+2007-11-30,Comparative study of the growth of sputtered aluminum oxide films on organic and inorganic substrates,"We present a comparative study of the growth of the technologically highly
+relevant gate dielectric and encapsulation material aluminum oxide in inorganic
+and also organic heterostructures. Atomic force microscopy studies indicate
+strong similarities in the surface morphology of aluminum oxide films grown on
+these chemically different substrates. In addition, from X-ray reflectivity
+measurements we extract the roughness exponent \beta of aluminum oxide growth
+on both substrates. By renormalising the aluminum oxide roughness by the
+roughness of the underlying organic film we find good agreement with \beta as
+obtained from the aluminum oxide on silicon oxide (\beta = 0.38 \pm 0.02),
+suggesting a remarkable similarity of the aluminum oxide growth on the two
+substrates under the conditions employed.",0711.5019v1
+2008-05-30,A brief comment on the chemical formulae of the rare earth iron arsenide oxide superconductors,"Just a brief comment on the chemical formulae of the rare earth iron arsenide
+oxide superconductors",0805.4668v1
+2010-02-18,Nanocrystal Growth on Graphene with Various Degrees of Oxidation,"We show a general two-step method to grow hydroxide and oxide nanocrystals of
+the iron family elements (Ni, Co, Fe) on graphene with two degrees of
+oxidation. Drastically different nanocrystal growth behaviors were observed on
+low-oxidation graphene sheets (GS) and highly oxidized graphite oxide (GO) in
+hydrothermal reactions. Small particles pre-coated on GS with few
+oxygen-containing surface groups diffused and recrystallized into
+single-crystalline nickel hydroxide Ni(OH)2 hexagonal nanoplates or iron oxide
+Fe2O3 nanorods with well defined morphologies. In contrast, particles
+pre-coated on GO were pinned by the high-concentration oxygen groups and
+defects on GO without recrystallization into well-defined shapes. Adjusting
+reaction temperature can be combined to further control materials grown on
+graphene. For materials with weak interactions with graphene, increasing the
+reaction temperature can lead to diffusion and recrystallization of surface
+species into larger crystals even on highly oxidized and defective GO. Our
+results suggest an interesting new approach to controlling the morphology of
+nanomaterials grown on graphene by tuning the surface chemistry of graphene as
+substrates for crystal nucleation and growth.",1002.3435v1
+2011-04-06,Crucible aperture: an effective way to reduce source oxidation in oxide molecular beam epitaxy process,"Growing multi-elemental complex-oxide structures using an MBE (Molecular Beam
+Epitaxy) technique requires precise control of each source flux. However, when
+the component elements have significantly different oxygen affinities,
+maintaining stable fluxes for easily oxidizing elements is challenging because
+of a source oxidation problem. Here, using Sr as a test source, we show that a
+crucible aperture insert scheme significantly reduces the source oxidation in
+an oxide-MBE environment. The crucible aperture insert was shaped like a disk
+with a hole at the center and was mounted inside the crucible; it blocks most
+of the oxygen species coming to the source, thus reducing the source oxidation.
+However, the depth of the aperture disk was critical for its performance; an
+ill-positioned aperture could make the flux stability even worse. With an
+optimally positioned aperture insert, the crucible exhibited more than four
+times improvement in Sr flux stability, compared to a conventional,
+non-apertured crucible.",1104.1120v1
+2016-02-22,Iron Oxide Surfaces,"The surface science of iron oxides is comprehensively reviewed. For the full
+abstract please see pdf.",1602.06774v1
+2016-10-26,"Atomic bonding and electrical potential at metal/oxide interfaces, a first principle study","A number of electronic devices involve metal/oxide interfaces in their
+structure where the oxide layer plays the role of electrical insulator. As the
+downscaling of devices continues, the oxide thickness can spread over only a
+few atomic layers, making the role of interfaces prominent on its insulating
+properties. The prototypical Al/SiO2 metal/oxide interface is investigated
+using first principle calculations, and the effect of the interfacial atomic
+bonding is evidenced. It is shown that the interface bonding configuration
+critically dictates the mechanical and electronic properties of the interface.
+Oxygen atoms are found to better delimit the oxide boundaries than cations.
+Interfacial cation-metal bonds allow the metal potential to leak inside the
+oxide layer, without atomic diffusion, leading to a virtual oxide thinning.",1610.08371v1
+2018-02-21,Precursors of gate oxide degradation in SiC power MOSFETs,"Gate oxide degradation is more critical in Silicon-Carbide (SiC) MOSFETs than
+in Silicon (Si) MOSFETs. This is because of the smaller gate oxide thickness
+and the higher electric field that develops across the gate oxide in SiC
+MOSFETs. While multiple precursors have been identified for monitoring the gate
+oxide degradation in Si MOSFETs, very few precursors have been identified for
+SiC MOSFETs. The purpose of this paper is to demonstrate that gate oxide
+degradation precursors used in Si MOSFETs: a) threshold voltage, b) gate
+plateau voltage and c) gate plateau time, can also be used as precursors for
+SiC MOSFETS. Moreover, all three precursors are found to exhibit a simultaneous
+increasing trend (during the stress time) leading to an increase in on-state
+loss, switching loss and switching time of the SiC MOSFET. The existing studies
+of gate oxide degradation mechanisms in SiC MOSFETs, and their effects on
+threshold voltage and mobility were extended to correlate a variation of all
+three precursors using analytical expressions. The increasing trends of
+precursors were experimentally confirmed by inducing gate oxide degradation in
+commercial SiC MOSFET samples.",1802.08085v1
+2014-03-05,Strong Oxidation Resistance of Atomically Thin Boron Nitride Nanosheets,"Investigation on oxidation resistance of two-dimensional (2D) materials is
+critical for many of their applications, because 2D materials could have higher
+oxidation kinetics than their bulk counterparts due to predominant surface
+atoms and structural distortions. In this study, the oxidation behavior of
+high-quality boron nitride (BN) nanosheets of 1-4 layer thick has been examined
+by heating in air. Atomic force microscopy and Raman spectroscopy analyses
+reveal that monolayer BN nanosheets can sustain up to 850 {\deg}C and the
+starting temperature of oxygen doping/oxidation of BN nanosheets only slightly
+increases with the increase of nanosheet layer and depends on heating
+conditions. Elongated etch lines are found on the oxidized monolayer BN
+nanosheets, suggesting that the BN nanosheets are first cut along the
+chemisorbed oxygen chains and then the oxidative etching grows perpendicularly
+to these cut lines. The stronger oxidation resistance of BN nanosheets suggests
+that they are more preferable for high-temperature applications than graphene.",1403.1002v1
+2008-07-22,Modelling the onset of oxide formation on metal surfaces from first principles,"The formation of ultrathin oxide layers on metal surfaces is a
+non-thermally-activated process which takes place spontaneously at very low
+temperatures within nanoseconds. This paper reports mechanistic details of the
+initial oxidation of bare metal surfaces, in particular Al(111) and TiN(001),
+as obtained by means of first-principles molecular dynamics modelling within
+the Density-Functional Theory. It is shown that the reactions of bare metal
+surfaces with O2 molecules take place according to a 'hot-atom' dissociative
+mechanism which is triggered by the filling of the sigma-star antibonding
+molecular orbital and is characterised by a sudden release of a large amount of
+kinetic energy. This released energy provides a driving force for metal/oxygen
+place-exchange processes which are responsible for the onset of oxide formation
+at virtually 0 K and at oxygen coverages well below 1 monolayer (ML). Further
+simulations of the oxidation reactions reveal that a disordered ultrathin oxide
+forms on Al(111), whereas a rather ordered structure develops on TiN(001)
+following a selective oxidation process which leaves clusters of Ti vacancies
+in the TiN lattice underneath the oxide layer.",0807.3430v1
+2013-09-22,Fine tuning of micropillar cavity modes through repetitive oxidations,"Repetitive wet thermal oxidations of a tapered oxide aperture in a
+micropillar structure are demonstrated. After each oxidation step the confined
+optical modes are analyzed at room temperature. Three regimes are identified.
+First, the optical confinement increases when the aperture oxidizes towards the
+center. Then, the cavity modes shift by more than 30 nm, when the taper starts
+to oxidize through the center, leading to a decrease in the optical path
+length. Finally, the resonance frequency levels o?f, when the aperture is
+oxidized all the way through the micropillar, but confined optical modes with a
+high quality factor remain. This repetitive oxidation technique therefore
+enables precise control of the optical cavity volume or wavelength.",1309.5943v1
+2015-12-11,Chromatic annuli formation and sample oxidation on copper thin films by femtosecond laser,"We report an experimental investigation on the irradiation of copper thin
+films with high repetition rate femtosecond laser pulses (1040 nm, 50 MHz), in
+ambient air and liquid water. We observe a novel, striking phenomenon of
+chromatic copper oxides (cupric oxide and cuprous oxide) annuli generation. The
+characteristic features of the chromatic copper oxide annuli are studied by
+exploiting micro-Raman Spectroscopy, Optical and Scanning Electron
+Microscopies. In the case of irradiation in water, the seldom investigated
+effects of the immersion time, after irradiation with a fixed number of pulses,
+is analyzed, and an intriguing dependence of the color of the chromatic annuli
+on the immersion time is observed. This remarkable behavior is explained by
+proposing an interpretation scenario addressing the various processes involved
+in the process. Our experimental findings show that cuprous oxide nanoparticles
+(size of ~20 nm) and cuprous oxide nanocubes (nanocube edges of ~30, ~60 nm)
+with extremely fine sizes can be effectively generated by exploiting high
+repetition rate laser-assisted oxidation.",1512.03546v1
+2017-10-08,Chemical Bonding Analysis on Amphoteric Hydrogen - Alkaline Earth Ammine Borohydrides,"Usually the ions in solid are in the positive oxidation states or in the
+negative oxidation state depending upon the chemical environment. It is highly
+unusual for an ion having both positive as well as negative oxidation state in
+a particular compound. Structural analysis suggest that the alkaline earth
+ammine borohydrides (AABH) with the chemical formula M (BH4)2(NH3)2 (M = Mg,
+Ca, or Sr) where hydrogen is present in +1 and -1 oxidation states. In order to
+understand the oxidation states of hydrogen and also the character of chemical
+bond present in AABH we have made charge density, electron localization
+function, Born effective charge, Bader effective charge, and density of states
+analyses using result from the density functional calculations. Our detailed
+analyses show that hydrogen is in amphoteric behavior with hydrogen closer to
+boron is in negative oxidation state and that closer to nitrogen is in the
+positive oxidation state. Due to the presence of finite covalent bonding
+between the consitutents in AABH the oxidation state of hydrogen is
+non-interger value. The confirmation of the presence of amphtoric behavior of
+hydrogen in AABH has implication in hydrogen storage applications.",1710.04272v1
+2019-07-10,Symmetry-Protected Degeneracies in the Electronic Band Structure of Oxidized Black Phosphorous,"We explore the oxidation of a single layer of black phosphorous using ab
+initio density functional theory calculation. We search for the equilibrium
+structures of phosphorene oxides, PO$_x$ with various oxygen concentrations $x$
+($0{\le}x{\le}1$). By evaluating the formation energies with diverse
+configurations and their vibrational properties for each of various $x$ values,
+we identify a series of stable oxidized structures with $x$ and confirm that
+the oxidation occurs naturally. We also find that oxidation makes some modes
+from the P-O bonds P-P bonds IR-active implying that the infrared spectra can
+be used to determine the degree of oxidation of phosphorene. Our electronic
+structure calculation reveals that the fully oxidized phosphorene (PO) has a
+direct band gap of 0.83 eV similar to the pristine phosphorene. Intriguingly,
+the PO possesses two nonsymmorphic symmetries with the inversion symmetry
+broken, guaranteeing a symmetry-protected band structures including the band
+degeneracy and four-fold degenerate Dirac points. Our results may provide a
+significant insight into the intriguing relations between symmetry of lattice
+and band topology of electrons.",1907.04550v1
+2017-05-19,Charge transfer driven emergent phenomena in oxide heterostructures,"Complex oxides exhibit many intriguing phenomena, including metal-insulator
+transition, ferroelectricity/multiferroicity, colossal magnetoresistance and
+high transition temperature superconductivity. Advances in epitaxial thin film
+growth techniques enable us to combine different complex oxides with atomic
+precision and form an oxide heterostructure. Recent theoretical and
+experimental work has shown that charge transfer across oxide interfaces
+generally occurs and leads to a great diversity of emergent interfacial
+properties which are not exhibited by bulk constituents. In this report, we
+review mechanisms and physical consequence of charge transfer across interfaces
+in oxide heterostructures. Both theoretical proposals and experimental
+measurements of various oxide heterostructures are discussed and compared. We
+also review the theoretical methods that are used to calculate charge transfer
+across oxide interfaces and discuss the success and challenges in theory.
+Finally, we present a summary and perspectives for future research.",1705.06962v1
+2021-02-26,Data Analytics Approach to Predict High-Temperature Cyclic Oxidation Kinetics of NiCr-based Alloys,"Although of practical importance, there is no established modeling framework
+to accurately predict high-temperature cyclic oxidation kinetics of
+multi-component alloys due to the inherent complexity. We present a data
+analytics approach to predict the oxidation rate constant of NiCr-based alloys
+as a function of composition and temperature with a highly consistent and
+well-curated experimental dataset. Two characteristic oxidation models, i.e., a
+simple parabolic law and a statistical cyclic-oxidation model, have been chosen
+to numerically represent the high-temperature oxidation kinetics of commercial
+and model NiCr-based alloys. We have successfully trained machine learning (ML)
+models using highly ranked key input features identified by correlation
+analysis to accurately predict experimental parabolic rate constants (kp). This
+study demonstrates the potential of ML approaches to predict oxidation kinetics
+of alloys over a wide composition and temperature ranges. This approach can
+also serve as a basis for introducing more physically meaningful ML input
+features to predict the comprehensive cyclic oxidation behavior of
+multi-component high-temperature alloys with proper constraints based on the
+known underlying mechanisms.",2102.13261v1
+2021-06-09,High diffusivity pathways govern massively enhanced oxidation during tribological sliding,"The lifetime of moving metallic components is often limited by accelerated
+oxidation. Yet, the mechanisms and pathways for oxidation during tribological
+loading are not well understood. Using copper as a model system,
+tribologically-induced oxidation is systematically investigated by varying the
+sliding speed and test duration under mild tribological loading. We demonstrate
+that tribo-oxidation is controlled by test duration rather than the number of
+cycles or the sliding speed. Plastic deformation from tribological loading
+creates dislocations, grain and phase boundaries that act as high diffusivity
+pathways. A combination of electron microscopy and atom probe tomography
+revealed significantly enhanced atomic concentration of the diffusing species
+around dislocations. Oxygen diffusion into the bulk as well as of copper
+towards the free surface along these defects control the oxide formation
+kinetics. Our work paves the way for formulating a physics-based understanding
+for tribo-oxidation, which is crucial to develop strategies to prevent
+oxidation and to strategically tailor surfaces to increase the lifetime of
+engineering systems.",2106.04849v2
+2022-02-27,Molecular rectifiers with very high rectification ratio enabled by oxidative damage in double-stranded DNA,"In this work, we report a novel strategy to construct molecular diodes with a
+record tunable rectification ratio of as high as 10^6 using oxidatively damaged
+DNA molecules. Being exposed to several endogenous and exogenous events, DNA
+suffers constant oxidative damages leading to oxidation of guanine to
+8-Oxoguanine (8oxoG). Here, we study the charge migration properties of native
+and oxidatively damaged DNA using a multiscale multiconfigurational methodology
+comprising of molecular dynamics, density functional theory and kinetic Monte
+Carlo simulations. We perform a comprehensive study to understand the effect of
+different concentrations and locations of 8oxoG in a dsDNA sequence on its CT
+properties and find tunable rectifier properties having potential applications
+in molecular electronics such as molecular switches and molecular rectifiers.
+We also discover the negative differential resistance properties of fully
+oxidized Drew-Dickerson sequence. The presence of 8oxoG guanine leads to the
+trapping of charge, thus operates as a charge sink, which reveals how oxidized
+guanine saves the rest of the genome from further oxidative damage.",2202.13443v1
+2022-09-01,Why Ultrafast Photo-induced CO Desorption Dominates over Oxidation on Ru(0001),"CO oxidation on Ru(0001) is a long-standing example of a reaction that, being
+thermally forbidden in ultra-high vacuum, can be activated by femtosecond laser
+pulses. In spite of its relevance, the precise dynamics of the photo-induced
+oxidation process as well as the reasons behind the dominant role of the
+competing CO photo-desorption remain unclear. Here we use ab initio molecular
+dynamics with electronic friction that account for the highly excited and
+non-equilibrated system created by the laser to investigate both reactions. Our
+simulations successfully reproduce the main experimental findings: the
+existence of photo-induced oxidation and desorption, the large desorption to
+oxidation branching ratio, and the changes in the O K-edge X-ray absorption
+spectra attributed to the initial stage of the oxidation process. Now, we are
+able to monitor in detail the ultrafast CO desorption and CO oxidation
+occurring in the highly-excited system and to disentangle what causes the
+unexpected inertness to the otherwise energetically favored oxidation.",2209.00518v1
+2022-11-29,Composition based oxidation state prediction of materials using deep learning,"Oxidation states are the charges of atoms after their ionic approximation of
+their bonds, which have been widely used in charge-neutrality verification,
+crystal structure determination, and reaction estimation. Currently only
+heuristic rules exist for guessing the oxidation states of a given compound
+with many exceptions. Recent work has developed machine learning models based
+on heuristic structural features for predicting the oxidation states of metal
+ions. However, composition based oxidation state prediction still remains
+elusive so far, which is more important in new material discovery for which the
+structures are not even available. This work proposes a novel deep learning
+based BERT transformer language model BERTOS for predicting the oxidation
+states of all elements of inorganic compounds given only their chemical
+composition. Our model achieves 96.82\% accuracy for all-element oxidation
+states prediction benchmarked on the cleaned ICSD dataset and achieves 97.61\%
+accuracy for oxide materials. We also demonstrate how it can be used to conduct
+large-scale screening of hypothetical material compositions for materials
+discovery.",2211.15895v1
+2023-05-19,A stable and low loss oxide for superconducting qubits,"The dielectric loss of amorphous oxide layers is a major limiting factor for
+the coherent time of superconducting qubits. Usually, the surface oxides of
+superconductor film are lossy and unstable in air. To increase the coherence
+time, it is essential for qubits to have stable and low dielectric loss oxides,
+either as barrier or passivation layers. Here, we demonstrate that a kind of
+amorphous tantalum oxide on Ta film is robust and stable by means of chemical
+and structural analysis. Such kind of oxide layer forms in a self-limiting
+process on the surface of {\alpha}-Ta (110) film in piranha solution, yielding
+stable thickness and steady chemical composition. Quarter-wavelength coplanar
+waveguide resonators are made to study the loss of this oxide. An internal
+quality factor of above three million is measured at single photon level for
+fresh device, and it is still over two million even after exposed to air for
+months. Furthermore, we propose a method to fabricate all-tantalum
+superconducting qubits using this kind of oxide as the dielectric and
+passivation layers.",2305.11395v1
+2023-12-11,Features of nanocontact formed using point electrical breakdown of a niobium oxide nanolayer,"The electrical characteristics of a point section of niobium oxide between a
+massive cathode made of a superconducting indium-tin alloy and a niobium film
+before the oxide breakdown and the nanocontact that appears after the breakdown
+of the oxide at room temperature have been studied. The dependences of the
+point breakdown voltage of the oxide and the resistance of nanocontacts on the
+method of breakdown and the thickness of the oxide in the range of 15-60 nm
+have been established. In particular, a minimum value of the breakdown current
+has been established (about 1 {\mu}A), below which breakdown does not occur.
+The voltage-current characteristic (VCC) of the oxide has a semiconductor
+character and indicates the dependence of the breakdown voltage of the oxide on
+its polarity. The VCC of the nanocontact is nonlinear, which is associated with
+phase transitions in the nanocontact material caused by its heating by the
+transport current.",2312.06816v1
+2024-01-30,Electrical characterization of gadolinium oxide deposited by high pressure sputtering with in situ plasma oxidation,"In this work, we characterized gadolinium oxide films deposited on silicon by
+high pressure sputtering with a two-step process: first, we sputtered metallic
+gadolinium in an argon atmosphere and then, we performed an in-situ plasma
+oxidation of the metallic layer previously deposited. By means of high
+resolution transmission electron microscopy, we can detect the oxidation degree
+of the metallic film. Under optimized deposition conditions, fully oxidized
+Gd2O3 films are obtained. In addition, the capacitance and conductance as a
+function of gate voltage of Pt gated metal-insulator-semiconductor capacitors
+confirm stable dielectric behavior of the fully oxidized films. The devices
+show low gate leakage currents (1e5 A/cm2 at 1 V for 2.2 nm of equivalent oxide
+thickness), low interface trap density and an almost negligible hysteresis and
+frequency dispersion.",2402.00889v1
+2024-02-29,Three-dimensional atomic interface between metal and oxide in Zr-ZrO2 nanoparticles,"Metal-oxide interfaces with poor coherency have unique properties comparing
+to the bulk materials and offer broad applications in the fields of
+heterogeneous catalysis, battery, and electronics. However, current
+understanding of the three-dimensional (3D) atomic metal-oxide interfaces
+remains limited because of their inherent structural complexity and limitations
+of conventional two-dimensional imaging techniques. Here, we determine the 3D
+atomic structure of metal-oxide interfaces in zirconium-zirconia nanoparticles
+using atomic-resolution electron tomography. We quantitatively analyze the
+atomic concentration and the degree of oxidation, and find the coherency and
+translational symmetry of the interfaces are broken. Moreover, we observe
+porous structures such as Zr vacancies and nano-pores and investigate their
+distribution. Our findings provide a clear 3D atomic picture of metal-oxide
+interface with direct experimental evidence. We anticipate this work could
+encourage future studies on fundamental problems of oxides such as interfacial
+structures in semiconductor and atomic motion during oxidation process.",2402.18943v1
+2004-09-27,On the Magnetic Excitation Spectra of High Tc Cu Oxides up to the Energies far above the Resonance Energy,"Magnetic excitation spectra c""(q,w) of YBa2Cu3Oy and La214 systems have been
+studied. For La1.88Sr0.12CuO4, c""(q,w) have been measured up to ~30 meV and
+existing data have been analyzed up to the energy w~150 meV by using the
+phenomenological expression of the generalized magnetic susceptibility
+c(q,w)=c0(q,w)/{1+J(q)c0(q,w)}, where c0(q,w) is the susceptibility of the
+electrons without the exchange coupling J(q) among them. In the relatively low
+energy region up to slightly above the resonance energy Er, it has been
+reported by the authors' group that the expression can explain characteristics
+of the q- and w-dependence of the spectra of YBa2Cu3Oy (YBCO or YBCOy). Here,
+it is also pointed out that the expression can reproduce the rotation of four
+incommensurate peaks of c""(q,w) within the a*-b* plane about (p/a, p/a) {or
+so-called (p, p)} point by 45 degree, which occurs as w goes to the energy
+region far above Er from E below Er. For La2-xSrxCuO4 and La2-xBaxCuO4,
+agreements between the observed results and the calculations are less
+satisfactory than for YBCO, indicating that we have to take account of the
+existence of the ""stripes"" to consistently explain the observed c""(q,w) of
+La214 system especially near x=1/8.",0409675v1
+2005-12-20,Magnetoresistance Effects in SrFeO(3-x): Dependence on Phase Composition and Relation to Magnetic and Charge Order,"Single crystals of iron(IV) rich oxides SrFeO(3-x) with controlled oxygen
+content have been studied by Moessbauer spectroscopy, magnetometry,
+magnetotransport measurements, Raman spectroscopy, and infrared ellipsometry in
+order to relate the large magnetoresistance (MR) effects in this system to
+phase composition, magnetic and charge order. It is shown that three different
+types of MR effects occur. In cubic SrFeO3 (x = 0) a large negative MR of 25%
+at 9 T is associated with a hitherto unknown 60 K magnetic transition and a
+subsequent drop in resistivity. The 60 K transition appears in addition to the
+onset of helical ordering at ~130 K. In crystals with vacancy-ordered
+tetragonal SrFeO(3-x) as majority phase (x ~0.15) a coincident
+charge/antiferromagnetic ordering transition near 70 K gives rise to a negative
+giant MR effect of 90% at 9 T. A positive MR effect is observed in tetragonal
+and orthorhombic materials with increased oxygen deficiency (x = 0.19, 0.23)
+which are insulating at low temperatures. Phase mixtures can result in a
+complex superposition of these different MR phenomena. The MR effects in
+SrFeO(3-x) differ from those in manganites as no ferromagnetic states are
+involved.",0512510v1
+2006-02-14,Magnetic properties of superconducting cobalt oxides NaxCoO2.yH2O,"Studies of the NMR Knight shift K of Na0.3CoO2.yH2O have been carried out in
+detail. The suppression of K by the occurrence of the superconductivity
+reported previously by the present authors in both magnetic field directions
+perpendicular and parallel to the c axis has been confirmed, indicating that
+the Cooper pairs are in the singlet state. The anisotropy of the suppression
+amplitudes is consistent with the anisotropy of the hyperfine coupling constant
+Aspin estimated by the K-kai plot. It has also been found that even samples,
+which do not exhibit a significant amount of the Curie-Weiss-like increase of
+the uniform magnetic susceptibility kai with decreasing temperature T, exhibit
+the superconducting transition, which indicates that the superconducting
+Na0.3CoO2.1.3H2O is not necessarily be in the proximity region of the
+ferromagnetic phase. It has also been confirmed that the superconducting
+transition temperature Tc of the samples prepared by mixing Na0.7CoO2, H2O (or
+D2O) and bromine for 4 h, and separating the resultant powder from the solution
+by filtration, depends on the elapsed time t after filtration. For these
+samples, the Curie constant of kai estimated at low temperatures increases with
+t, supporting the idea that the number of the lattice imperfection possibly due
+to the oxygen-vacancy-formation increases with t. Even for such samples, the
+superconductivity appears, which seems to exclude the possibility of the
+anisotropic superconducting order parameter. These results are favorable for
+the full-gapped superconductivity.",0602323v1
+2006-12-06,Epitaxial Bi2FeCrO6 Multiferroic Thin Films,"We present here experimental results obtained on Bi2FeCrO6 (BFCO) epitaxial
+films deposited by laser ablation directly on SrTiO3 substrates. It has been
+theoretically predicted, by Baettig and Spaldin, using first-principles density
+functional theory that BFCO is ferrimagnetic (with a magnetic moment of 2 Bohr
+magneton per formula unit) and ferroelectric (with a polarization of ~80
+microC/cm2 at 0K). The crystal structure has been investigated using X-ray
+diffraction which shows that the films are epitaxial with a high crystallinity
+and have a degree of orientation depending of the deposition conditions and
+that is determined by the substrate crystal structure. Chemical analysis
+carried out by X-ray Microanalysis and X-ray Photoelectron Spectroscopy (XPS)
+indicates the correct cationic stoichiometry in the BFCO layer, namely
+(Bi:Fe:Cr = 2:1:1). XPS depth profiling revealed that the oxidation state of Fe
+and Cr ions in the film remains 3+ throughout the film thickness and that both
+Fe and Cr ions are homogeneously distributed throughout the depth.
+Cross-section high-resolution transmission electron microscopy images together
+with selected area electron diffraction confirm the crystalline quality of the
+epitaxial BFCO films with no identifiable foreign phase or inclusion. The
+multiferroic character of BFCO is proven by ferroelectric and magnetic
+measurements showing that the films exhibit ferroelectric and magnetic
+hysteresis at room temperature. In addition, local piezoelectric measurements
+carried out using piezoresponse force microscopy (PFM) show the presence of
+ferroelectric domains and their switching at the sub-micron scale.",0612168v1
+2009-07-17,A First-Principles Study of Zinc Oxide Honeycomb Structures,"We present a first-principles study of the atomic, electronic, and magnetic
+properties of two-dimensional (2D), single and bilayer ZnO in honeycomb
+structure and its armchair and zigzag nanoribbons. In order to reveal the
+dimensionality effects, our study includes also bulk ZnO in wurtzite,
+zincblende, and hexagonal structures. The stability of 2D ZnO, its nanoribbons
+and flakes are analyzed by phonon frequency, as well as by finite temperature
+ab initio molecular-dynamics calculations. 2D ZnO in honeycomb structure and
+its armchair nanoribbons are nonmagnetic semiconductors but acquire net
+magnetic moment upon the creation of zinc-vacancy defect. Zigzag ZnO
+nanoribbons are ferromagnetic metals with spins localized at the oxygen atoms
+at the edges and have high spin polarization at the Fermi level. However, they
+change to nonmagnetic metal upon termination of their edges with hydrogen
+atoms. From the phonon calculations, the fourth acoustical mode specified as
+twisting mode is also revealed for armchair nanoribbon. Under tensile stress
+the nanoribbons are deformed elastically maintaining honeycomblike structure
+but yield at high strains. Beyond yielding point honeycomblike structure
+undergo a structural change and deform plastically by forming large polygons.
+The variation in the electronic and magnetic properties of these nanoribbons
+have been examined under strain. It appears that plastically deformed
+nanoribbons may offer a new class of materials with diverse properties.",0907.3070v2
+2010-04-02,Flux pinning on nano-sized defects and critical current in HTc superconductors,"New results of the investigations critical current problems in the high
+temperature oxide superconductors are presented, basing on an analysis of the
+flux pinning on nano-sized centers. New model of the interaction pancake
+vortices with the nano-sized centers is proposed, while comparison of obtained
+results with others pinning forces approaches presented. The energy balance
+approach is applied, which leads to the appearance of the potential barrier
+determining the pancake vortices movement in the flux creep process. Various
+initial positions of the captured vortex have been analyzed, while variation of
+the screening currents for such configuration has been considered and initial
+calculations of the influence this effect on the current-voltage
+characteristics performed. The dependence of the critical current on the
+pinning centers parameters has been obtained while comparison with experimental
+data is given. Pinning force has been calculated and its temperature
+dependence, which is in qualitative agreement with an experiment. Critical
+current determines the magnetic induction profiles and therefore flux trapping,
+very important parameter from the point of view of an application HTc
+superconductors as permanent magnets. The influence of the critical current on
+the flux trapping in ceramic granular superconductors is calculated as well as
+influence of various other material parameters - grain radius, surface barrier,
+fulfillment of the ceramic with superconducting grains. Influence of the
+critical current on a.c. losses in second generation HTc tapes with magnetic
+substrate is discussed briefly too.",1004.0316v1
+2010-06-10,NMR study on the stability of the magnetic ground state in MnCr${}_2$O${}_4$,"The canting angles and fluctuation of the magnetic ion spins of spinel oxide
+MnCr${}_2$O${}_4$ were studied by nuclear magnetic resonance (NMR) at low
+temperatures, which has a collinear ferrimagnetic order below $T_C$ and a
+ferrimagnetic spiral order below $T_s < T_C$. Contrary to previous reports,
+only one spin canting angle of Cr ions was observed. The spin canting angles of
+Mn and Cr ions in the ferrimagnetic spiral obtained at a liquid-He temperature
+were $43\,^{\circ}$ and $110\,^{\circ}$, respectively. The nuclear spin-spin
+relaxation was determined by the Suhl-Nakamura interaction at low temperatures
+but the relaxation rate $T_2^{-1}$ increases rapidly as the temperature
+approaches $T_s$. This indicates that the fluctuation of the spiral component
+becomes faster as the temperature increases but not fast enough to leave an
+averaged hyperfine field to nuclei in the time scale of nuclear spin precession
+in the ferrimagnetic phase, which is on the order of $10^{-8}$ s. The spiral
+volume fraction measured for various temperatures reveals that the collinear
+and the spiral ferrimagnetic phases are mixed below the transition temperature
+of the spiral order. The temperature hysteresis in the volume fraction implies
+that this transition has first-order characteristics.",1006.1983v1
+2010-09-28,Absence of Ferromagnetism in Mn-doped Tetragonal Zirconia,"In a recent letter, it has been predicted within first principle studies that
+Mn-doped ZrO2 compounds could be good candidate for spintronics application
+because expected to exhibit ferromagnetism far beyond room temperature. Our
+purpose is to address this issue experimentally for Mn-doped tetragonal
+zirconia. We have prepared polycrystalline samples of Y0.15(Zr0.85-yMny)O2
+(y=0, 0.05, 0.10, 0.15 & 0.20) by using standard solid state method at
+equilibrium. The obtained samples were carefully characterized by using x-ray
+diffraction, scanning electron microscopy, elemental color mapping, X-ray
+photoemission spectroscopy and magnetization measurements. From the detailed
+structural analyses, we have observed that the 5% Mn doped compound
+crystallized into two symmetries (dominating tetragonal & monoclinic), whereas
+higher Mn doped compounds are found to be in the tetragonal symmetry only. The
+spectral splitting of the Mn 3s core-level x-ray photoelectron spectra confirms
+that Mn ions are in the Mn3+ oxidation state and indicate a local magnetic
+moment of about 4.5 {\mu}B/Mn. Magnetic measurements showed that compounds up
+to 10% of Mn doping are paramagnetic with antiferromagnetic interactions.
+However, higher Mn doped compound exhibits local ferrimagnetic ordering. Thus,
+no ferromagnetism has been observed for all Mn-doped tetragonal ZrO2 samples.",1009.5583v2
+2011-08-10,"Interactions between Magnetic Nanowires and Living Cells : Uptake, Toxicity and Degradation","We report on the uptake, toxicity and degradation of magnetic nanowires by
+NIH/3T3 mouse fibroblasts. Magnetic nanowires of diameters 200 nm and lengths
+comprised between 1 {\mu}m and 40 {\mu}m are fabricated by controlled assembly
+of iron oxide ({\gamma}-Fe2O3) nanoparticles. Using optical and electron
+microscopy, we show that after 24 h incubation the wires are internalized by
+the cells and located either in membrane-bound compartments or dispersed in the
+cytosol. Using fluorescence microscopy, the membrane-bound compartments were
+identified as late endosomal/lysosomal endosomes labeled with lysosomal
+associated membrane protein (Lamp1). Toxicity assays evaluating the
+mitochondrial activity, cell proliferation and production of reactive oxygen
+species show that the wires do not display acute short-term (< 100 h) toxicity
+towards the cells. Interestingly, the cells are able to degrade the wires and
+to transform them into smaller aggregates, even in short time periods (days).
+This degradation is likely to occur as a consequence of the internal structure
+of the wires, which is that of a non-covalently bound aggregate. We anticipate
+that this degradation should prevent long-term asbestos-like toxicity effects
+related to high aspect ratio morphologies and that these wires represent a
+promising class of nanomaterials for cell manipulation and microrheology.",1108.2081v1
+2011-08-29,"Magnetization Dynamics, Throughput and Energy Dissipation in a Universal Multiferroic Nanomagnetic Logic Gate with Fan-in and Fan-out","The switching dynamics of a multiferroic nanomagnetic NAND gate with
+fan-in/fan-out is simulated by solving the Landau-Lifshitz-Gilbert (LLG)
+equation while neglecting thermal fluctuation effects. The gate and logic wires
+are implemented with dipole-coupled 2-phase (magnetostrictive/piezoelectric)
+multiferroic elements that are clocked with electrostatic potentials of ~50 mV
+applied to the piezoelectric layer generating 10 MPa stress in the
+magnetostrictive layers for switching. We show that a pipeline bit throughput
+rate of ~ 0.5 GHz is achievable with proper magnet layout and sinusoidal
+four-phase clocking. The gate operation is completed in 2 ns with a latency of
+4 ns. The total (internal + external) energy dissipated for a single gate
+operation at this throughput rate is found to be only ~ 1000 kT in the gate and
+~3000 kT in the 12-magnet array comprising two input and two output wires for
+fan-in and fan-out. This makes it respectively 3 and 5 orders of magnitude more
+energy-efficient than complementary-metal-oxide-semiconductor-transistor (CMOS)
+based and spin-transfer-torque-driven nanomagnet based NAND gates. Finally, we
+show that the dissipation in the external clocking circuit can always be
+reduced asymptotically to zero using increasingly slow adiabatic clocking, such
+as by designing the RC time constant to be 3 orders of magnitude smaller than
+the clocking period. However, the internal dissipation in the device must
+remain and cannot be eliminated if we want to perform fault-tolerant classical
+computing.
+  Keywords: Nanomagnetic logic, multiferroics, straintronics and spintronics,
+Landau-Lifshitz-Gilbert equation.",1108.5758v1
+2011-12-12,"Crystal Growth and Physical Properties of SrCu2As2, SrCu2Sb2 and BaCu2Sb2","We report the growth of single crystals of SrCu2As2, SrCu2Sb2,
+SrCu2(As{0.84}Sb{0.16})2 and BaCu2Sb2 using the self-flux technique and their
+structural, magnetic, thermal and transport properties that were investigated
+by powder x-ray diffraction (XRD), magnetic susceptibility chi, specific heat
+Cp and electrical resistivity rho measurements versus temperature T from 1.8 to
+350 K. Rietveld refinements of XRD patterns for crushed crystals confirm that
+SrCu2As2 crystallizes in the ThCr2Si2-type structure and SrCu2Sb2 crystallizes
+in the CaBe2Ge2-type structure. However, BaCu2Sb2 is found to have a large unit
+cell consisting of three blocks. Here a ThCr2Si2-type block is sandwiched
+between two CaBe2Ge2-type blocks along the c-axis, as reported, but likely with
+a monoclinic distortion. The chi data of all these compounds are diamagnetic
+and reveal nearly T-independent anisotropic behavior. The finite values of the
+Sommerfeld linear specific heat coefficients gamma and the T dependences of rho
+reveal metallic character of all four compounds. The electronic and magnetic
+properties indicate that these compounds are sp metals with Cu in the 3d^{10}
+electronic configuration corresponding to the oxidation state Cu^{+1}, as
+previously predicted theoretically for (Sr,Ba)Cu2As2 by D. J. Singh. We find
+that SrCu2As2 has a collapsed-tetragonal structure. The electronic character of
+the Cu and the strength of the As-As interlayer bonding are both expected to
+drastically change between weakly Cu-substituted BaFe2As and pure BaCu2As2.",1112.2722v2
+2012-09-23,Tunable ferroelectricity in artificial tri-layer superlattices comprised of non-ferroic components,"Heterostructured material systems devoid of ferroic components are presumed
+not to display ordering associated with ferroelectricity. In heterostructures
+composed of transition metal oxides, however, the disruption introduced by an
+interface can affect the balance of the competing interactions among electronic
+spins, charges and orbitals. This has led to the emergence of properties absent
+in the original building blocks of a heterostructure, including metallicity,
+magnetism and superconductivity. Here we report the discovery of
+ferroelectricity in artificial tri-layer superlattices consisting solely of
+non-ferroelectric NdMnO3/SrMnO3/LaMnO3 layers. Ferroelectricity was observed
+below 40 K exhibiting strong tunability by superlattice periodicity.
+Furthermore, magnetoelectric coupling resulted in 150% magnetic modulation of
+the polarization. Density functional calculations indicate that broken space
+inversion symmetry and mixed valency, because of cationic asymmetry and
+interfacial polar discontinuity, respectively, give rise to the observed
+behavior. Our results demonstrate the engineering of asymmetric layered
+structures with emergent ferroelectric and magnetic field tunable functions
+distinct from that of normal devices, for which the components are typically
+ferroelectrics.",1209.5070v1
+2012-09-28,"Quantum dynamics of a single, mobile spin impurity","Quantum magnetism describes the properties of many materials such as
+transition metal oxides and cuprate superconductors. One of its elementary
+processes is the propagation of spin excitations. Here we study the quantum
+dynamics of a deterministically created spin-impurity atom, as it propagates in
+a one-dimensional lattice system. We probe the full spatial probability
+distribution of the impurity at different times using single-site-resolved
+imaging of bosonic atoms in an optical lattice. In the Mott-insulating regime,
+a post-selection of the data allows to reduce the effect of temperature, giving
+access to a space- and time-resolved measurement of the quantum-coherent
+propagation of a magnetic excitation in the Heisenberg model. Extending the
+study to the bath's superfluid regime, we determine quantitatively how the bath
+strongly affects the motion of the impurity. The experimental data shows a
+remarkable agreement with theoretical predictions allowing us to determine the
+effect of temperature on the coherence and velocity of impurity motion. Our
+results pave the way for a new approach to study quantum magnetism, mobile
+impurities in quantum fluids, and polarons in lattice systems.",1209.6468v1
+2013-02-06,Magnetic irreversibility in ultrafine ZnFe2O4 partices,"Pure ultrafine ZnFe2O4 particles have been obtained from mechanosynthesis of
+the ZnO and Fe2O3 oxides. The average grain diameter was estimated from x-ray
+diffraction to be <d> = 36(6) nm. Refinement of neutron diffraction (ND) data
+showed that the resulting cubic spinel structure is oxygen-deficient, with ~7%
+of Fe3+ ions occupying the tetrahedral A sites. Magnetization curves taken at
+4.2 K showed absence of saturation up to fields H = 9 Tesla, associated to a
+spin-canted produced by the milling process. Field-cooled (FC) and
+zero-field-cooled (ZFC) curves showed irreversible behavior extending well
+above room temperature, which is associated to spin disorder. Annealing samples
+at 300 {\deg}C yields an average grain size <d> = 50(6) nm, and ~16% of Fe3+
+ions at A sites. Partial oxygen recovery is also deduced from neutron data
+refinement in annealed samples. Concurrently, decrease of magnetic
+irreversibility is noticed, assigned to partial recovery of the collinear spin
+structure. Complex M\""ossbauer spectra were observed at room temperature and 80
+K, with broad hyperfine field distributions spanning from ~10 T to ~40 T. At T
+= 4.2 K, hyperfine field distributions indicate high disorder in Fe local
+environments. The above data suggest the existence of Fe-rich clusters,
+yielding strong superexchange interactions between Fe ions at A and B sites of
+the spinel structure.",1302.1276v1
+2013-02-20,Spin-Triplet Superconductivity Induced by Longitudinal Ferromagnetic Fluctuations in UCoGe: Theoretical Aspect,"Identification of pairing mechanisms leading to the unconventional
+superconductivity realized in copper-oxide, heavy-fermions, and organic
+compounds is one of the most challenging issues in condensed-matter physics.
+Clear evidence for an electron-phonon mechanism in conventional superconductors
+is seen by the isotope effect on the superconducting transition temperatures
+$T_{\rm SC}$, since isotopic substitution varies the phonon frequency without
+affecting the electronic states. In unconventional superconductors, magnetic
+fluctuations have been proposed to mediate superconductivity, and considerable
+efforts have been made to unravel relationships between normal-state magnetic
+fluctuations and superconductivity. Here, we show that characteristic
+experimental results on the ferromagnetic (FM) superconductor UCoGe ($T_{\rm
+Curie} \sim 2.5 $ K and $T_{\rm SC} \sim 0.6$ K) can be understood consistently
+within a scenario of the spin-triplet superconductivity induced by FM spin
+fluctuations. Temperature and angle dependencies of the upper critical magnetic
+field of the superconductivity ($H_{c2}$) are calculated on the basis of the
+above scenario by solving the Eliashberg equation. Calculated $H_{c2}$ well
+agrees with the characteristic experimental results observed in UCoGe. This is
+a first example that FM fluctuations are shown to be a pairing glue of
+superconductivity.",1302.4827v1
+2015-04-29,"Study of grain boundary transparency in (Yb1-xCax)Ba2Cu3O bi-crystal thin films over a wide temperature, field and field orientation range","The residual low angle grain boundary (GB) network is still the most
+important current-limiting mechanism operating in bi-axially textured rare
+earth barium copper oxide (REBCO) coated conductors. While Ca-doping is well
+established to improve super-current flow across low angle GBs in weak fields
+at high temperatures, Ca-doping also depresses Tc, making it so far impractical
+for high temperature applications of REBCO coated conductors. On the other
+hand, high field magnet applications of REBCO require low temperatures. Here we
+systematically evaluate the effectiveness of Ca-doping in improving the GB
+transparency, r$^{GB}$= Jc$^{GB}$/Jc$^{grain}$ , of low angle Yb1-xCaxBaCuO
+[001] tilt bi-crystal films down to 10K and with magnetic fields perpendicular
+and parallel to the film surfaces, while varying the Ca and oxygen doping
+level. Using Low Temperature Scanning Laser Microscopy (LTSLM) and
+Magneto-Optical Imaging (MOI), we found rGB to strongly depend on the angle
+between magnetic field and the GB plane and clearly identified regimes in which
+Jc$^{GB}$ can exceed Jc$^{grain}$ (r$^{GB}$>1) where the GB pinning is
+optimized by the field being parallel to the GB dislocations. However, even in
+this favorable situation, we found that r$^{GB}$ became much smaller at lower
+temperatures. Calculations of the GB Ca segregation profile predict that the
+high Jc channels between the GB dislocation cores are almost Ca-free. It may be
+therefore that the positive effects of Ca doping seen by many authors near Tc
+are partly a consequence of the higher Tc of these Ca-free channels.",1504.07861v1
+2015-07-21,First principles study of the adsorption of MgO molecules on a clean Fe(001) surface,"The adsorption of MgO molecules on a Fe(001) surface was studied using
+density functional theory (DFT) and projector augmented wave methods. The
+energetically most favored configurations for different adsorption sites
+considered were identified. The most preferable adsorption geometry is when the
+MgO molecules are parallel to the surface, with Mg in the interstitial site and
+O in on-top of the Fe atom. During the adsorption of subsequent MgO molecules
+in this geometry, a sharp, non-oxidized interface is formed between the MgO
+adlayer and Fe(001) surface. The adsorption of MgO perpendicular to the
+surface, with oxygen incorporated in the topmost Fe layer is less probable, but
+may lead to the formation of the FeO layer when stabilized with an excess of
+oxygen atoms. Structural, electronic and magnetic properties of both interface
+types were examined for the MgO coverage from 1/9 to 1 monolayer (ML).
+Electronic and magnetic properties are sensitive to the MgO coverage. For lower
+coverage of MgO, clear hybridization between the Fe 3d and O 2p states is
+shown. The average magnetic moment of the surface Fe atoms is reduced with
+coverage, achieving 2.78 $\mu_{\rm B}$ for 1 ML of MgO.",1507.05803v2
+2015-10-29,Magnetic mechanisms of pairing in strongly correlated electron system of copper oxides,"The multielectron LDA+GTB approach has been developed to calculate electronic
+structure of strongly correlated cuprates. At low energies the effective
+Hamiltonian of the $t - t' - t"" - {t_ \bot } - {J^ * } - {J_ \bot }$-model has
+been derived with parameters coming from the ab initio calculation for LSCO.
+The electronic structure of LSCO has been calculated self-consistently with the
+short-range antiferromagnetic order for various doping level. Two Lifshitz-type
+quantum phase transitions with Fermi surface topology changes have been found
+at dopings $x_{c1}=0.15$ and $x_{c2}=0.24$. Its effect on normal and
+superconducting properties has been calculated. The interatomic exchange
+parameter and its pressure dependence has been calculated within LDA+GTB
+scheme. The magnetic mechanisms of d-wave pairing induced by static and
+dynamical spin correlations are discussed. Simultaneous treatment of magnetic
+and phonon pairing results in the conclusion that both contributions are of the
+same order. For two layer cuprates like YBCO the interlayer hopping and
+exchange effects on the electronic structure and doping dependence of $T_c$ is
+discussed as well as the Coulomb interaction induced mechanism of pairing.",1510.08640v2
+2016-02-02,Rydberg systems in parallel electric and magnetic fields: an improved method for finding exceptional points,"Exceptional points are special parameter points in spectra of open quantum
+systems, at which resonance energies degenerate and the associated eigenvectors
+coalesce. Typical examples are Rydberg systems in parallel electric and
+magnetic fields, for which we solve the Schr\""odinger equation in a complete
+basis to calculate the resonances and eigenvectors. Starting from an avoided
+crossing within the parameter-dependent spectra and using a two-dimensional
+matrix model, we develop an iterative algorithm to calculate the field
+strengths and resonance energies of exceptional points and to verify their
+basic properties. Additionally, we are able to visualise the wave functions of
+the degenerate states. We report the existence of various exceptional points.
+For the hydrogen atom these points are in an experimentally inaccessible regime
+of field strengths. However, excitons in cuprous oxide in parallel electric and
+magnetic fields, i. e., the corresponding hydrogen analogue in a solid state
+body, provide a suitable system, where the high-field regime can be reached at
+much smaller external fields and for which we propose an experiment to detect
+exceptional points.",1602.00909v3
+2016-06-07,Intra pseudogap- and superconductivity-pair spin and charge fluctuations and underdome metal-insulator (fermion-boson)-crossover phenomena as keystones of cuprate physics,"The most intriguing observation of cuprate experiments is most likely the
+metal-insulator-crossover (MIC), seen in the underdome region of the
+temperature-doping phase diagram of copper-oxides under a strong magnetic
+field, when the superconductivity is suppressed. This MIC, which results in
+such phenomena as heat conductivity downturn, anomalous Lorentz ratio,
+nonlinear entropy, insulating ground state, nematicity- and stripe-phases and
+Fermi pockets, reveals the nonconventional dielectric property of the
+pseudogap-normal phase. Since conventional superconductivity appears from a
+conducting normal phase, the understanding of how superconductivity arises from
+an insulating state becomes a fundamental problem and thus the keystone for all
+of cuprate physics. Recently, in interpreting the physics of visualization in
+scanning tunneling microscopy (STM) real space nanoregions (NRs), which exhibit
+an energy gap, we have succeeded in understanding that the minimum size for
+these NRs provides pseudogap and superconductivity pairs, which are single
+bosons. In this work, we discuss the intra-particle magnetic spin and charge
+fluctuations of these bosons, observed recently in hidden magnetic order and
+STM experiments. We find that all the mentioned MIC phenomena can be obtained
+in the Coulomb single boson and single fermion two liquid model, which we
+recently developed, and the MIC is a crossover of sample percolating NRs of
+single fermions into those of single bosons.",1606.02065v1
+2016-10-13,Monte Carlo Simulations of Spin Transport in a Strained Nanoscale InGaAs Field Effect Transistor,"Spin-based logic devices could operate at very high speed with very low
+energy consumption and hold significant promise for quantum information
+processing and metrology. Here, an in-house developed, experimentally verified,
+ensemble self-consistent Monte Carlo device simulator with a Bloch equation
+model using a spin-orbit interaction Hamiltonian accounting for Dresselhaus and
+Rashba couplings is developed and applied to a spin field effect transistor
+(spinFET) operating under externally applied voltages on a gate and a drain. In
+particular, we simulate electron spin transport in a \SI{25}{nm} gate length
+\chem{In_{0.7}Ga_{0.3}As} metal-oxide-semiconductor field-effect transistor
+(MOSFET) with a CMOS compatible architecture. We observe non-uniform decay of
+the net magnetization between the source and gate and a magnetization recovery
+effect due to spin refocusing induced by a high electric field between the gate
+and drain. We demonstrate coherent control of the polarization vector of the
+drain current via the source-drain and gate voltages, and show that the
+magnetization of the drain current is strain-sensitive and can be increased
+twofold by strain induced into the channel.",1610.04114v3
+2017-08-04,Interaction effects in assembly of magnetic nanoparticles,"A specific absorption rate of a dilute assembly of various random clusters of
+iron oxide nanoparticles in alternating magnetic field has been calculated
+using Landau- Lifshitz stochastic equation. This approach simultaneously takes
+into account both the presence of thermal fluctuations of the nanoparticle
+magnetic moments, and magneto-dipole interaction between the nanoparticles of
+the clusters. It is shown that for usual 3D clusters the intensity of magneto-
+dipole interaction is determined mainly by the cluster packing density eta =
+Np*V/Vcl, where Np is the average number of the particles in the cluster, V is
+the nanoparticle volume, and Vcl is the cluster volume. The area of the low
+frequency hysteresis loop and the assembly specific absorption rate have been
+found to be considerably reduced when the packing density of the clusters
+increases in the range of 0.005 < eta < 0.4. The dependence of the specific
+absorption rate on the mean nanoparticle diameter is retained with increase of
+eta, but becomes less pronounced. For fractal clusters of nanoparticles, which
+arise in biological media, in addition to considerable reduction of the
+absorption rate, the absorption maximum is shifted to smaller particle
+diameters. It is found also that the specific absorption rate of fractal
+clusters increases appreciably with increase of the thickness of nonmagnetic
+shells at the nanoparticle surfaces.",1708.01474v1
+2018-02-26,Capacitively Driven Global Interconnect with Magnetoelectric Switching Based Receiver for Higher Energy Efficiency,"We propose capacitively driven low-swing global interconnect circuit using a
+receiver that utilizes magnetoelectric (ME) effect induced magnetization
+switching to reduce the energy consumption. Capacitively driven wire has
+recently been shown to be effective in improving the performance of global
+interconnects. Such techniques can reduce the signal swing in the interconnect
+by using a capacitive divider network and does not require an additional
+voltage supply. However, the large reduction in signal swing makes it necessary
+to use differential signaling and amplification for successful regeneration at
+the receiver, which add area and static power. ME effect induced magnetization
+reversal has recently been proposed which shows the possibility of using a low
+voltage to switch a nanomagnet adjacent to a multi-ferroic oxide. Here, we
+propose an ME effect based receiver that uses the low voltage at the receiving
+end of the global wire to switch a nanomagnet. The nanomagnet is also used as
+the free layer of a magnetic tunnel junction (MTJ), the resistance of which is
+tuned through the ME effect. This change in MTJ resistance is converted to full
+swing binary signals by using simple digital components. This process allows
+capacitive low swing interconnection without differential signaling or
+amplification, which leads to significant energy efficiency. Our simulation
+results indicate that for 5-10 mm long global wires in IBM 45 nm technology,
+capacitive ME design consumes 3x lower energy compared to full-swing CMOS
+design and 2x lower energy compared to differential amplifier based low-swing
+capacitive CMOS design.",1802.10431v1
+2018-04-01,Structural color tuning in 1D photonic crystals with electric field and magnetic field,"A tuning of the light transmission properties of 1D photonic structures
+employing an external stimulus is very attracting and opens the way to the
+fabrication of optical switches for colour manipulation in sensing, lighting,
+and display technology. We present the electric field-induced tuning of the
+light transmission in a photonic crystal device, made by alternating layers of
+silver nanoparticles and titanium dioxide nanoparticles. We show a shift of
+around 10 nm for an applied voltage of 10 V. We ascribe the shift to an
+accumulation of charges at the silver/TiO2 interface due to electric field,
+resulting in an increase of the number of charges contributing to the plasma
+frequency in silver, giving rise to a blue shift of the silver plasmon band,
+with concomitant blue shift of the photonic band gap. The employment of a
+relatively low applied voltage gives the possibility to build a compact and
+low-cost device. We also propose the fabrication of 1D photonic crystal and
+microcavities employing a magneto-optical material as TGG (Tb3Ga5O12). With
+these structures we can observe a shift of 22 nm with a magnetic field of 5 T,
+at low temperature (8 K). The option to tune the colour of a photonic crystal
+with magnetic field is interesting because of the possibility to realize
+contactless optical switches. We also discuss the possibility to achieve the
+tuning of the photonic band gap with UV light in photonic crystals made with
+indium tin oxide (ITO).",1804.04491v1
+2018-04-17,Enhanced magnetic and thermoelectric properties in epitaxial polycrystalline SrRuO3 thin film,"Transition metal oxide thin films show versatile electrical, magnetic, and
+thermal properties which can be tailored by deliberately introducing
+macroscopic grain boundaries via polycrystalline solids. In this study, we
+focus on the modification of the magnetic and thermal transport properties by
+fabricating single- and polycrystalline epitaxial SrRuO3 thin films using
+pulsed laser epitaxy. Using epitaxial stabilization technique with atomically
+flat polycrystalline SrTiO3 substrate, epitaxial polycrystalline SrRuO3 thin
+film with crystalline quality of each grain comparable to that of
+single-crystalline counterpart is realized. In particular, alleviated
+compressive strain near the grain boundaries due to coalescence is evidenced
+structurally, which induced enhancement of ferromagnetic ordering of the
+polycrystalline epitaxial thin film. The structural variations associated with
+the grain boundaries further reduce the thermal conductivity without
+deteriorating the electronic transport, and lead to enhanced thermoelectric
+efficiency in the epitaxial polycrystalline thin films, compared with their
+single-crystalline counterpart.",1804.06077v1
+2020-07-09,Large magnetoresistance and non-zero Berry phase in the nodal-line semimetal MoO2,"We performed calculations of the electronic band structure and the Fermi
+surface as well as measured the longitudinal resistivity rhoxx(T,H), Hall
+resistivity rhoxy(T,H) and quantum oscillations of the magnetization as a
+function of temperature at various magnetic fields for MoO2 with monoclinic
+crystal structure. The band structure calculations show that MoO2 is a
+nodal-line semimetal when spin-orbit coupling is ignored. It was found that a
+large magnetoresistance reaching 5.03x10^4% at 2 K and 9 T, its nearly
+quadratic field dependence and a field-induced up-turn behavior of rhoxx(T),
+the characteristics common for many topologically non-trivial as well as
+trivial semimetals, emerge also in MoO2. The observed properties are attributed
+to a perfect charge-carrier compensation, evidenced by both calculations
+relying on the Fermi surface topology and the Hall resistivity measurements.
+Both the observation of negative magnetoresistance for magnetic field along the
+current direction and the non-zero Berry phase in de Haas-van Alphen
+measurements indicate that pairs of Weyl points appear in MoO2, which may be
+due to the crystal symmetry breaking. These results highlight MoO2 as a new
+platform materials for studying the topological properties of oxides.",2007.04814v1
+2013-08-12,Diamond Magnetometry of Superconducting Thin Films,"In recent years diamond magnetometers based on the nitrogen-vacancy (NV)
+center have been of considerable interest for magnetometry applications at the
+nanoscale. An interesting application which is well suited for NV centers is
+the study of nanoscale magnetic phenomena in superconducting materials. We
+employ the magnetic sensitivity of NV centers in diamond to interrogate the
+magnetic properties of a thin-layer yttrium barium copper oxide (YBCO)
+superconductor. Using fluorescence-microscopy methods and samples integrated
+with an NV sensor on a microchip, we measure the temperature of phase
+transition in the layer to be 70.0(2) K, and the penetration field of vortices
+to be 46(4) G. We observe the pinning of the vortices in the layer at 65 K, and
+estimate their density after cooling the sample in a ~ 10 G field to be 0.45(1)
+\mu m^{-2}. These measurements are done with a 10 nm thick NV layer, so that
+high spatial resolution may be enabled in the future. Based on these results,
+we anticipate that this magnetometer could be useful for imaging the structure
+and dynamics of vortices. As an outlook, we present a fabrication method for a
+superconductor chip designed for this purpose.",1308.2689v3
+2013-08-21,Asymmetry of collective excitations in electron and hole doped cuprate superconductors,"High-temperature superconductivity (HTSC) mysteriously emerges upon doping
+holes or electrons into insulating copper oxides with antiferromagnetic (AFM)
+order. It has been thought that the large energy scale of magnetic excitations,
+compared to phonon energies for example, lies at the heart of an
+electronically-driven superconducting phase at high temperatures. However,
+despite extensive studies, little information is available for comparison of
+high-energy magnetic excitations of hole- and electron-doped superconductors to
+assess a possible correlation with the respective superconducting transition
+temperatures. Here, we use resonant inelastic x-ray scattering (RIXS) at the Cu
+L3-edge to reveal high-energy collective excitations in the archetype
+electron-doped cuprate Nd2-xCexCuO4 (NCCO). Surprisingly, despite the fact that
+the spin stiffness is zero and the AFM correlations are short-ranged, magnetic
+excitations harden significantly across the AFM-HTSC phase boundary, in stark
+contrast with the hole-doped cuprates. Furthermore, we find an unexpected and
+highly dispersive mode in superconducting NCCO that is undetected in the
+hole-doped compounds, which emanates from the zone center with a characteristic
+energy comparable to the pseudogap, and may signal a quantum phase distinct
+from superconductivity. The uncovered asymmetry in the high-energy collective
+excitations with respect to hole and electron doping provides additional
+constraints for modeling the HTSC cuprates.",1308.4740v2
+2018-05-24,Vortex excitations in the Insulating State of an Oxide Interface,"In two-dimensional (2D) superconductors an insulating state can be induced
+either by applying a magnetic field, $H$, or by increasing disorder. Many
+scenarios have been put forth to explain the superconductor to insulator
+transition (SIT): dominating fermionic physics after the breaking of Cooper
+pairs, loss of phase coherence between superconducting islands embedded in a
+metallic or insulating matrix and localization of Cooper pairs with concomitant
+condensation of vortex-type excitations. The difficulty in characterizing the
+insulating state and its origin stems from the lack of a continuous mapping of
+the superconducting to insulating phase diagram in a single sample. Here we use
+the two-dimensional (2D) electron liquid formed at the interface between the
+two insulators (111) SrTiO$_3$ and LaAlO$_3$ to study the superconductor to
+insulator transition. This crystalline interface surprisingly exhibits very
+strong features previously observed only in amorphous systems. By use of
+electrostatic gating and magnetic fields, the sample is tuned from the metallic
+region, where supeconductivity is fully manifested, deep into the insulating
+state. Through examination of the field dependence of the sheet resistance and
+comparison of the response to fields in different orientations we identify a
+new magnetic field scale, H$_{pairing}$, where superconducting fluctuations are
+muted. Our findings show that vortex fluctuations excitations and Cooper pair
+localization are responsible for the observed SIT and that these excitations
+surprisingly persist deep into the insulating state.",1805.09574v1
+2011-11-17,Resonant magnetic exciton mode in the heavy-fermion antiferromagnet CeB6,"Resonant magnetic excitations are widely recognized as hallmarks of
+unconventional superconductivity in copper oxides, iron pnictides, and
+heavy-fermion compounds. Numerous model calculations have related these modes
+to the microscopic properties of the pair wave function, but the mechanisms
+underlying their formation are still debated. Here we report the discovery of a
+similar resonant mode in the non-superconducting, antiferromagnetically ordered
+heavy-fermion metal CeB6. Unlike conventional magnons, the mode is
+non-dispersive, and its intensity is sharply concentrated around a wave vector
+separate from those characterizing the antiferromagnetic order. The magnetic
+intensity distribution rather suggests that the mode is associated with a
+coexisting order parameter of the unusual antiferro-quadrupolar phase of CeB6,
+which has long remained ""hidden"" to the neutron-scattering probes. The mode
+energy increases continuously below the onset temperature for
+antiferromagnetism, in parallel to the opening of a nearly isotropic spin gap
+throughout the Brillouin zone. These attributes bear strong similarity to those
+of the resonant modes observed in unconventional superconductors below their
+critical temperatures. This unexpected commonality between the two disparate
+ground states indicates the dominance of itinerant spin dynamics in the ordered
+low-temperature phases of CeB6 and throws new light on the interplay between
+antiferromagnetism, superconductivity, and ""hidden"" order parameters in
+correlated-electron materials.",1111.4151v1
+2014-06-10,Role of MgO impurity on the superconducting properties of MgB2,"We address the effect of MgO impurity on the superconducting properties of
+MgB2. The synthesis of MgB2 is very crucial because of sensitivity of Mg to
+oxidation which may lead to MgO as a secondary phase. Rietveld refinement was
+performed to determine the quantitative volume fraction of MgO in the samples
+synthesized by two different techniques. Both the samples were subjected to
+magnetization measurements under dc and ac applied magnetic fields and the
+observed results were compared as a function of temperature. Paramagnetic
+Meissner effect has been observed in a sample of MgB2 having more amount of MgO
+(with Tc = 37.1K) whereas the pure sample MgB2 having minor quantity of MgO
+shows diamagnetic Meissner effect with Tc = 38.8K. M-H measurements at 10K
+reveal a slight difference in irreversibility field which is due to MgO
+impurity along with wide transition observed from ac magnetic susceptibility
+measurements. The magnetotransport measurements R(T)H using RN = 90%, 50% and
+10% criterion on pure sample of MgB2 has been used to determine the upper
+critical field whereas the sample having large quantity of MgO does not allow
+these measurements due to its high resistance.",1406.2414v2
+2014-06-20,Spin-orbit density wave: A new phase of matter applicable to the hidden order state of URu2Si2,"We provide a brief review and detailed analysis of the spin-orbit density
+wave (SODW), proposed as a possible explanation to the `hidden order' phase of
+URu2Si2. Due to the interplay between inter-orbital Coulomb interaction and
+spin-orbit coupling (SOC) in this compound, the SODW is shown to arise from
+Fermi surface nesting instability between two spin-orbit split bands. An
+effective low-energy Hamiltonian including single-particle SOC and two-particle
+SODW is derived, while numerical results are calculated by using
+density-functional theory (DFT) based band structure input. Computed gapped
+quasiparticle spectrum, entropy loss and spin-excitation spectrum are in
+detailed agreement with experiments. Interestingly, despite the fact that SODW
+governs dynamical spin-excitations, the static magnetic moment is calculated to
+be zero, owing to the time-reversal invariance imposed by SOC. As a
+consequence, SODW can be destroyed by finite magnetic field even at zero
+temperature. Our estimation of the location of the quantum critical point is
+close to the experimental value of Bc ~ 35 T. Finally, we extend the idea of
+SODW to other SOC systems including iridium oxides (iridates) and
+two-dimensional electronic systems such as BiAg2 surface and LaAlO3/SrTiO3
+interface. We show hints of quasiparticle gapping, reduction of preexisting
+magnetic moment, large magneto-resistance etc. in these systems which can be
+explained consistently within the SODW theory.",1406.5271v2
+2016-05-02,Interfilament Resistance at 77 K in Striated HTS Coated Conductors,"Striating HTS coated conductor (CC) tapes into narrow filaments offers the
+possibility of reducing the tapes' magnetization losses without unreasonably
+decreasing their current-carrying capability. However, realizing well-separated
+striations presents technological challenges, especially if the number of
+filaments is large and/or if a thick layer of metallic stabilizer is present.
+In these situations, the filaments can be easily coupled and their
+effectiveness to reduce magnetization losses is strongly diminished or
+eliminated. While the onset of coupling is well visible from magnetization loss
+measurements, the actual path of the coupling current is unknown. In this
+contribution we present a systematic study of the transverse resistance in HTS
+CC samples in order to get a deeper understanding of those paths. The measured
+samples differ in terms of manufacturer (SuperPower and SuperOx), and presence
+and thickness of stabilizer material. In addition, oxidation is used as a means
+to increase the resistance between the filaments in non-stabilized samples. The
+results are interpreted with a chain network model. This work provides useful
+insights on the factors determining the transverse resistance in striated HTS
+CCs, thus indicating ways to improve the effectiveness of the striation process
+for AC loss reduction.",1605.00401v2
+2016-08-17,Electronic tunability of the frustrated triangular-lattice cluster magnet LiZn$_{2-x}$Mo$_3$O$_8$,"LiZn$_2$Mo$_3$O$_8$ is an electrically insulating geometrically frustrated
+antiferromagnet in which inorganic Mo$_3$O$_{13}$ clusters each behaves as a
+single $S = 1/2$ unit, with the clusters arranged on a two-dimensional
+triangular lattice. Prior results have shown that LiZn$_2$Mo$_3$O$_8$ does not
+exhibit static magnetic order down to at least $T = 0.05\,K$, and instead
+possesses a valence bond ground state. Here, we show that LiZn$_2$Mo$_3$O$_8$
+can be hole doped by oxidation with $\mathrm{I}_2$ and subsequent removal of
+$\mathrm{Zn}^{2+}$ cations to access the entire range of electron count, from
+one to zero unpaired electrons per site on the triangular lattice. Contrary to
+expectations, no metallic state is induced; instead, the primary effect is to
+suppress the number of sites contributing to the condensed valence-bond state.
+Further, diffraction and pair-distribution function analysis show no evidence
+for local Jahn-Teller distortions or other deviations from the parent trigonal
+symmetry as a function of doping or temperature. Taken together, the data and
+density functional theory calculations indicate that removal of electrons from
+the magnetic layers favors Anderson localization of the resulting hole and an
+increase in the electrical band-gap over the formation of a metallic and
+superconducting state. These results put strong constraints on the chemical
+conditions necessary to realize metallic states from parent insulating
+geometrically frustrated antiferromagnets.",1608.05022v1
+2017-07-07,Exciton-phonon interaction breaking all antiunitary symmetries in external magnetic fields,"Recent experimental investigations by M. A{\ss}mann et al. [Nature Mater. 15,
+741 (2016)] on the spectrum of magnetoexcitons in cuprous oxide revealed the
+statistics of a Gaussian unitary ensemble (GUE). The model of F. Schweiner et
+al. [Phys. Rev. Lett. 118, 046401 (2017)], which includes the complete cubic
+valence band structure of the solid, can explain the appearance of GUE
+statistics if the magnetic field is not oriented in one of the symmetry planes
+of the cubic lattice. However, it cannot explain the experimental observation
+of GUE statistics for all orientations of the field. In this paper we
+investigate the effect of quasi-particle interactions or especially the
+exciton-phonon interaction on the level statistics of magnetoexcitons and show
+that the motional Stark field induced by the exciton-phonon interaction leads
+to the occurrence of GUE statistics for arbitrary orientations of the magnetic
+field in agreement with experimental observations. Importantly, the breaking of
+all antiunitary symmetries can be explained only by considering both the
+exciton-phonon interaction and the cubic crystal lattice.",1707.02869v1
+2017-12-10,"Tuning the Interfacial Charge, Orbital and Spin Polarization Properties in La0.67Sr0.33MnO3/ La1-xSrxMnO3 Bilayers","The possibility of controlling the interfacial properties of artificial oxide
+heterostructures is still attracting researchers in the field of materials
+engineering. Here, we used surface sensitive techniques and high-resolution
+transmission electron microscopy to investigate the evolution of the surface
+spin-polarization and lattice strains across the interfaces between
+La0.66Sr0.33MnO3 thin films and low-doped manganites as capping layers. We have
+been able to finely tune the interfacial spin-polarization by changing the
+capping layer thickness and composition. The spin-polarization was found to be
+highest at a critical capping thickness that depends on the Sr doping. We
+explain the non-trivial magnetic profile by the combined effect of two
+mechanisms. On one hand, the extra carriers supplied by the low-doped
+manganites that tend to compensate the overdoped interface, favouring locally a
+ferromagnetic double-exchange coupling. On the other hand, the evolution from a
+tensile-strained structure of the inner layers to a compressed structure at the
+surface that changes gradually the orbital occupation and hybridization of the
+3d-Mn orbitals, being detrimental for the spin polarization. The finding of an
+intrinsic spin-polarization at the A-site cation observed in XMCD measurements
+reveals also the existence of a complex magnetic configuration at the
+interface, different from the magnetic phases observed at the inner layers.",1712.03611v1
+2018-09-24,Probing spin correlations using angle resolved photoemission in a coupled metallic/Mott insulator system,"A nearly free electron metal and a Mott insulating state can be thought of as
+opposite ends of possibilities for the motion of electrons in a solid. In the
+magnetic oxide metal PdCrO$_{2}$, these two coexist as alternating layers.
+Using angle resolved photoemission, we surprisingly find sharp band-like
+features in the one-electron removal spectral function of the correlated
+subsystem. We show that these arise because a hole created in the Mott layer
+moves to and propagates in the metallic layer while retaining memory of the
+Mott layer's magnetism. This picture is quantitatively supported by a strong
+coupling analysis capturing the physics of PdCrO$_{2}$ in terms of a Kondo
+lattice Hamiltonian. Our findings open new routes to use the non-magnetic probe
+of photoemission to gain insights into the spin-susceptibility of correlated
+electron systems.",1809.08972v2
+2018-10-24,Magnetostriction studies up to megagauss fields using fiber Bragg grating technique,"We here report magnetostriction measurements under pulsed megagauss fields
+using a high-speed 100 MHz strain monitoring system devised using fiber Bragg
+grating (FBG) technique with optical filter method. The optical filter method
+is a detection scheme of the strain of FBG, where the changing Bragg wavelength
+of the FBG reflection is converted to the intensity of reflected light to
+enable the 100 MHz measurement. In order to show the usefulness and reliability
+of the method, we report the measurements for solid oxygen, spin-controlled
+crystal, and volborthite, a deformed Kagom\'{e} quantum spin lattice, using
+static magnetic fields up to 7 T and non-destructive millisecond pulse magnets
+up to 50 T. Then, we show the application of the method for the
+magnetostriction measurements of CaV$_{4}$O$_{9}$, a two-dimensional
+antiferromagnet with spin-halves, and LaCoO$_{3}$, an anomalous spin-crossover
+oxide, in the megagauss fields.",1810.10472v2
+2019-07-30,Antiferromagnetic Topological Insulator MnBi2Te4: Synthesis and Magnetic properties,"Recently, MnBi2Te4 has been discovered as the first intrinsic
+antiferromagnetic topological insulator (AFM TI), and will become a promising
+material to discover exotic topological quantum phenomena. In this work, we
+have realized the successful synthesis of high-quality MnBi2Te4 single crystals
+by solid-state reactions. The as-grown MnBi2Te4 single crystal exhibits a van
+der Waals layered structure, which is composed of septuple Te-Bi-Te-Mn-Te-Bi-Te
+sequences as determined by powder X-ray diffraction (PXRD) and high-resolution
+high-angle annular dark field scanning transmission electron microscopy
+(HAADF-STEM). The magnetic order below 25 K as a consequence of A-type
+antiferromagnetic interaction between Mn layers in the MnBi2Te4 crystal
+suggests the unique interplay between antiferromagnetism and topological
+quantum states. The transport measurements of MnBi2Te4 single crystals further
+confirm its magnetic transition. Moreover, the unstable surface of MnBi2Te4,
+which is found to be easily oxidized in air, deserves attention for onging
+research on few-layer samples. This study on the first AFM TI of MnBi2Te4 will
+guide the future research on other potential candidates in the MBixTey family
+(M = Ni, V, Ti, etc.).",1907.13018v1
+2019-09-11,Magnetic anisotropy in single crystal high entropy perovskite oxide La(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 films,"Local configurational disorder can have a dominating role in the formation of
+macroscopic functional responses in strongly correlated materials. Here, we use
+entropy-stabilization synthesis to create single crystal epitaxial ABO3
+perovskite thin films with equal atomic concentration of 3d transition metal
+cations on the B-site sublattice. X-ray diffraction, atomic force microscopy,
+and scanning transmission electron microscopy of
+La(Cr0.2Mn0.2Fe0.2Co0.2Ni0.2)O3 (L5BO) films demonstrate excellent
+crystallinity, smooth film surfaces, and uniform mixing of the 3d transition
+metal cations throughout the B-site sublattice. The magnetic properties are
+strongly dependent on substrate-induced lattice anisotropy and suggest the
+presence of long-range magnetic order in these exceptionally disordered
+materials. The ability to populate multiple elements onto a single sublattice
+in complex crystal structures opens new possibilities to design functionality
+in correlated systems and enable novel fundamental studies seeking to
+understand how diverse local bonding environments can work to generate
+macroscopic responses, such as those driven by electron-phonon channels and
+complex exchange interaction pathways.",1909.05019v1
+2019-09-20,Giant topological Hall effect in correlated oxide thin films,"Strong electronic correlations can produce remarkable phenomena such as
+metal-insulator transitions and greatly enhance superconductivity,
+thermoelectricity, or optical non-linearity. In correlated systems, spatially
+varying charge textures also amplify magnetoelectric effects or
+electroresistance in mesostructures. However, how spatially varying spin
+textures may influence electron transport in the presence of correlations
+remains unclear. Here we demonstrate a very large topological Hall effect (THE)
+in thin films of a lightly electron-doped charge-transfer insulator, (Ca,
+Ce)MnO3. Magnetic force microscopy reveals the presence of magnetic bubbles,
+whose density vs. magnetic field peaks near the THE maximum, as is expected to
+occur in skyrmion systems. The THE critically depends on carrier concentration
+and diverges at low doping, near the metal-insulator transition. We discuss the
+strong amplification of the THE by correlation effects and give perspectives
+for its non-volatile control by electric fields.",1909.09305v1
+2019-10-03,Charge disproportionation and site-selective local magnetic moments in the post-perovskite-type Fe$_2$O$_3$ under ultra-high pressures,"The archetypal $3d$ Mott insulator hematite, Fe$_2$O$_3$, is one of the basic
+oxide components playing an important role in mineralogy of Earth's lower
+mantle. Its high pressure-temperature behavior, such as the electronic
+properties, equation of state, and phase stability is of fundamental importance
+for understanding the properties and evolution of the Earth's interior. Here,
+we study the electronic structure, magnetic state, and lattice stability of
+Fe$_2$O$_3$ at ultra-high pressures using the density functional plus dynamical
+mean-field theory (DFT+DMFT) approach. In the vicinity of a Mott transition,
+Fe$_2$O$_3$ is found to exhibit a series of complex electronic, magnetic, and
+structural transformations. In particular, it makes a phase transition to a
+metal with a post-perovskite crystal structure and site-selective local moments
+upon compression above 75 GPa. We show that the site-selective phase transition
+is accompanied by a charge disproportionation of Fe ions, with Fe$^{3\pm
+\delta}$ and $\delta \sim 0.05$-$0.09$, implying a complex interplay between
+electronic correlations and the lattice. Our results suggest that
+site-selective local moments in Fe$_2$O$_3$ persist up to ultra-high pressures
+of $\sim$200-250 GPa, i.e., sufficiently above the core-mantle boundary. The
+latter can have important consequences for understanding of the velocity and
+density anomalies in the Earth's lower mantle.",1910.01702v1
+2019-10-21,Satellite orbital drag during magnetic storms,"We investigate satellite orbital drag effects at low-Earth orbit (LEO)
+associated with thermosphere heating during magnetic storms caused by coronal
+mass ejections. CHAllenge Mini-satellite Payload (CHAMP) and Gravity Recovery
+And Climate Experiment (GRACE) neutral density data are used to compute orbital
+drag. Storm-to-quiet density comparisons are performed with background
+densities obtained by the Jacchia-Bowman 2008 (JB2008) empirical model. Our
+storms are grouped in different categories regarding their intensities as
+indicated by minimum values of the SYM-H index. We then perform superposed
+epoch analyses with storm main phase onset as zero epoch time. In general, we
+find that orbital drag effects are larger for CHAMP (lower altitudes) in
+comparison to GRACE (higher altitudes). Results show that storm-time drag
+effects manifest first at high latitudes, but for extreme storms particularly
+observed by GRACE stronger orbital drag effects occur during early main phase
+at low/equatorial latitudes, probably due to heating propagation from high
+latitudes. We find that storm-time orbital decay along the satellites' path
+generally increases with storm intensity, being stronger and faster for the
+most extreme events. For these events, orbital drag effects decrease faster
+probably due to elevated cooling effects caused by nitric oxide, which
+introduce modeled density uncertainties during storm recovery phase. Errors
+associated with total orbit decay introduced by JB2008 are generally the
+largest for the strongest storms, and increase during storm times, particular
+during recovery phases. We discuss the implication of these uncertainties for
+the prediction of collision between space objects at LEO during magnetic
+storms.",1910.09622v1
+2020-01-16,L1 data fitting for robust reconstruction in magnetic particle imaging: quantitative evaluation on Open MPI dataset,"Magnetic particle imaging is an emerging quantitative imaging modality,
+exploiting the unique nonlinear magnetization phenomenon of superparamagnetic
+iron oxide nanoparticles for recovering the concentration. Traditionally the
+reconstruction is formulated into a penalized least-squares problem with
+nonnegativity constraint, and then solved using a variant of Kaczmarz method
+which is often stopped early after a small number of iterations. Besides the
+phantom signal, measurements additionally include a background signal and a
+noise signal. In order to obtain good reconstructions, a preprocessing step of
+frequency selection to remove the deleterious influences of the noise is often
+adopted. In this work, we propose a complementary pure variational approach to
+noise treatment, by viewing highly noisy measurements as outliers, and
+employing the l1 data fitting, one popular approach from robust statistics.
+When compared with the standard approach, it is easy to implement with a
+comparable computational complexity. Experiments with a public domain dataset,
+i.e., Open MPI dataset, show that it can give accurate reconstructions, and is
+less prone to noisy measurements, which is illustrated by quantitative (PSNR /
+SSIM) and qualitative comparisons with the Kaczmarz method. We also investigate
+the performance of the Kaczmarz method for small iteration numbers
+quantitatively.",2001.06083v2
+2021-01-19,Room-temperature colossal magnetoresistance in terraced single-layer graphene,"Disorder-induced magnetoresistance (MR) effect is quadratic at low
+perpendicular magnetic fields and linear at high fields. This effect is
+technologically appealing, especially in the two-dimensional (2D) materials
+such as graphene, since it offers potential applications in magnetic sensors
+with nanoscale spatial resolution. However, it is a great challenge to realize
+a graphene magnetic sensor based on this effect because of the difficulty in
+controlling the spatial distribution of disorder and enhancing the MR
+sensitivity in the single-layer regime. Here, we report a room-temperature
+colossal MR of up to 5,000% at 9 T in terraced single-layer graphene. By
+laminating single-layer graphene on a terraced substrate, such as TiO2
+terminated SrTiO3, we demonstrate a universal one order of magnitude
+enhancement in the MR compared to conventional single-layer graphene devices.
+Strikingly, a colossal MR of >1,000% was also achieved in the terraced graphene
+even at a high carrier density of ~1012 cm-2. Systematic studies of the MR of
+single-layer graphene on various oxide- and non-oxide-based terraced surfaces
+demonstrate that the terraced structure is the dominant factor driving the MR
+enhancement. Our results open a new route for tailoring the physical property
+of 2D materials by engineering the strain through a terraced substrate.",2101.07595v1
+2017-04-29,Competing spin liquids and hidden nematic order in spin ice with frustrated transverse exchange,"Frustration in magnetic interactions can give rise to disordered ground
+states with subtle and beautiful properties. The spin ices Ho2Ti2O7 and
+Dy2Ti2O7 exemplify this phenomenon, displaying a classical spin liquid state,
+with fractionalized magnetic--monopole excitations. Recently there has been
+great interest in closely-related ""quantum spin ice"" materials, following the
+realization that anisotropic exchange interactions could convert spin ice into
+a massively-entangled, quantum, spin liquid, where magnetic monopoles become
+the charges of an emergent quantum electrodynamics. Here we show that even the
+simplest model of a quantum spin ice, the XXZ model on the pyrochlore lattice,
+can realise a still-richer scenario. Using a combination of classical Monte
+Carlo simulation, semi--classical molecular--dynamics simulation, and analytic
+field theory, we explore the properties of this model for frustrated transverse
+exchange. We find not one, but three, competing forms of spin liquid, as well
+as a phase with hidden, spin-nematic, order. We explore the experimental
+signatures of each of these different states, making explicit predictions for
+inelastic neutron scattering. These results show an intriguing similarity to
+experiments on a range of pyrochlore oxides.",1705.00148v2
+2017-11-21,Spontaneous Hall effect induced by strain in Pr$_2$Ir$_2$O$_7$ epitaxial thin films,"Strongly correlated iridate pyrochlores with geometrically frustrated spins
+have been recognized as a potentially interesting group of oxide materials
+where novel topological phases may appear. A particularly attractive system is
+the metallic Pr$_2$Ir$_2$O$_7$, as it is known as a Fermi node semimetal
+characterized by quadratic band touching at the Brillouin zone center,
+suggesting that the topology of its electronic states can be tuned by moderate
+lattice strain. In this work we report the growth of epitaxial
+Pr$_2$Ir$_2$O$_7$ thin films grown by solid-state epitaxy. We show that the
+strained parts of the films give rise to a spontaneous Hall effect that
+persists up to 50 K without having spontaneous magnetization within our
+experimental accuracy. This indicates that a macroscopic time reversal symmetry
+(TRS) breaking appears at a temperature scale that is too high for the
+magnetism to be due to Pr 4$f$ moments, and must thus be related to magnetic
+order of the iridium 5$d$ electrons. The magnetotransport and Hall analysis
+results are consistent with the formation of a Weyl semimetal state that is
+induced by a combination of TRS breaking and cubic symmetry breaking due to
+lattice strain.",1711.07813v1
+2018-03-05,Widefield imaging of superconductor vortices with electron spins in diamond,"Understanding the mechanisms behind high-$T_{c}$ Type-II superconductors (SC)
+is still an open task in condensed matter physics. One way to gain further
+insight into the microscopic mechanisms leading to superconductivity is to
+study the magnetic properties of the SC in detail, for example by studying the
+properties of vortices and their dynamics. In this work we describe a new
+method of wide-field imaging magnetometry using nitrogen-vacancy (NV) centers
+in diamond to image vortices in an yttrium barium copper oxide (YBCO) thin
+film. We demonstrate quantitative determination of the magnetic field strength
+of the vortex stray field, the observation of vortex patterns for different
+cooling fields and direct observation of vortex pinning in our disordered YBCO
+film. This method opens prospects for imaging of the magnetic-stray fields of
+vortices at frequencies from DC to several megahertz within a wide range of
+temperatures which allows for the study of both high-$T_{C}$ and low-$T_{C}$
+SCs. The wide temperature range allowed by NV center magnetometry also makes
+our approach applicable for the study of phenomena like island
+superconductivity at elevated temperatures (e.g. in metal nano-clusters).",1803.01957v1
+2018-03-28,Perpendicular magnetic anisotropy at the Fe/MgAl$_2$O$_4$ interface: Comparative first-principles study with Fe/MgO,"We present a theoretical study on interfacial magnetocrystalline anisotropy
+for Fe/MgAl$_2$O$_4$. This system has a very small lattice mismatch at the
+interface and therefore is suitable for realizing a fully coherent
+ferromagnet/oxide interface for magnetic tunnel junctions. On the basis of
+density functional theory, we calculate the interfacial anisotropy constant
+$K_{\rm i}$ and show that this system has interfacial perpendicular magnetic
+anisotropy (PMA) with $K_{\rm i} \approx 1.2\,{\rm mJ/m^2}$, which is a little
+bit smaller than that of Fe/MgO ($K_{\rm i} \approx$ 1.5--1.7$\,{\rm mJ/m^2}$).
+Second-order perturbation analysis with respect to the spin-orbit interaction
+clarifies that the difference in $K_{\rm i}$ between Fe/MgAl$_2$O$_4$ and
+Fe/MgO originates from the difference in contributions from spin-flip
+scattering terms at the interface. We propose that the insertion of tungsten
+layers into the interface of Fe/MgAl$_2$O$_4$ is a promising way to obtain huge
+interfacial PMA with $K_{\rm i} \gtrsim 3\,{\rm mJ/m^2}$.",1803.10428v5
+2018-06-07,High Performance Metallic Amorphous Magnetic Flake-based Magnetodielectric Inductors,"Flake-shaped FeSi-based metallic amorphous alloy particles, having an aspect
+ratio as high as 175 to 1, were prepared by ball milling gas atomized amorphous
+powders of an effective diameter of 20 micrometers. The starting powder had a
+saturation magnetic flux density, Bs, of 1.5 T and a coercivity, Hc, of 94 A/m.
+The aspect ratio of the flakes, as well as their magnetic properties, were
+controlled by milling process parameters, such as duration, speed, and the
+type, mass and diameter of the milling balls. To minimize the oxidation of the
+charge, the powders were handled in an argon gas-purged glove box, milled in
+toluene, and subsequently dried in vacuo. Subsequently, soft magnetodielectric
+composites were prepared by suspending and aligning the FeSi-based powders in
+paraffin wax or epoxy resin. The composites were then pressed into toroids for
+measurements of their high frequency complex permeability by a vector network
+analyzer. The influence of the flake aspect ratio and volume loading fraction
+on the permeability of the composites were investigated. Results indicate that
+the composite permeability increases with the flake aspect ratio. For example,
+for a given loading factor of 30 vol.%, the composite permeability at 0.1 GHz
+nearly tripled and approached the value of 10 by increasing the aspect ratio of
+the FeSi-based inclusions from 1 (spheres) to greater than 175 to 1 (flakes).",1806.02486v2
+2018-08-16,Stabilization of three-dimensional charge order in YBa$_2$Cu$_3$O$_{6+x}$ via epitaxial growth,"Incommensurate charge order (CO) has been identified as the leading
+competitor of high-temperature superconductivity in all major families of
+layered copper oxides, but the perplexing variety of CO states in different
+cuprates has confounded investigations of its impact on the transport and
+thermodynamic properties. The three-dimensional (3D) CO observed in
+YBa$_2$Cu$_3$O$_{6+x}$ in high magnetic fields is of particular interest,
+because quantum transport measurements have revealed detailed information about
+the corresponding Fermi surface. Here we use resonant X-ray scattering to
+demonstrate 3D-CO in underdoped YBa$_2$Cu$_3$O$_{6+x}$ films grown epitaxially
+on SrTiO$_3$ in the absence of magnetic fields. The resonance profiles indicate
+that Cu sites in the charge-reservoir layers participate in the CO state, and
+thus efficiently transmit CO correlations between adjacent CuO$_2$ bilayer
+units. The results offer fresh perspectives for experiments elucidating the
+influence of 3D-CO on the electronic properties of cuprates without the need to
+apply high magnetic fields.",1808.05411v1
+2019-02-01,Nanoscale ferroelastic twins formed in strained LaCoO3 films,"The coexistence and coupling of ferroelasticity and magnetic ordering in a
+single material offers a great opportunity to realize novel devices with
+multiple tuning knobs. Complex oxides are a particularly promising class of
+materials to find multiferroic interactions as they often possess rich phase
+diagrams and the interactions are very sensitive to external perturbations.
+Still, there are very few examples of these systems. Here we report the
+observation of twinning domains in ferroelastic LaCoO3 epitaxial thin films and
+their geometric control of structural symmetry that are intimately linked to
+the material electronic and magnetic states. A unidirectional structural
+modulation is achieved by selective choice of substrates possessing two-fold
+rotational symmetry. This modulation perturbs the crystal field splitting
+energy, leading to unexpected in plane anisotropy of orbital configuration and
+magnetization. These findings demonstrate the utilization of structural
+modulation to control multiferroic interactions and may enable a great
+potential for stimulation of exotic phenomena through artificial domain
+engineering.",1902.00162v1
+2019-03-21,Quantum Spin Ice Dynamics in the Dipole-Octupole Pyrochlore Magnet Ce$_2$Zr$_2$O$_7$,"Neutron scattering measurements on the pyrochlore magnet Ce$_2$Zr$_2$O$_7$
+reveal an unusual crystal field splitting of its lowest $J$=5/2 multiplet, such
+that its ground state doublet is composed of m$_J$=$\pm$3/2, giving these
+doublets a dipole - octupole (DO) character with local Ising anisotropy. Its
+magnetic susceptibility shows weak antiferromagnetic correlations with
+$\theta_{CW}$=-0.4(2)K, leading to a naive expectation of an All-In, All-Out
+ordered state at low temperatures. Instead our low energy inelastic neutron
+scattering measurements show a dynamic quantum spin ice state, with suppressed
+scattering near |$\textbf{Q}$|=0, and no long range order at low temperatures.
+This is consistent with recent theory predicting symmetry enriched U(1) quantum
+spin liquids for such DO doublets decorating the pyrochlore lattice. Finally,
+we show that disorder, especially oxidation of powder samples, is important in
+Ce$_2$Zr$_2$O$_7$ and could play an important role in the low temperature
+behaviour of this material.",1903.09207v1
+2019-04-04,Impact of single and double oxygen vacancies on electronic transport in Fe/MgO/Fe magnetic tunnel junctions,"To study the impact of oxygen vacancies on spin-polarized transport, we have
+computed the electronic and transport properties of single (F centers) and
+paired (M centers) oxygen vacancies using density functional theory. These
+point defects can generate barrier heights as low as 0.4V for FeCo electrodes
+irrespective of the defect's spatial position within the barrier, and of the
+orientation of the M center. These defects promote a strong decrease in the
+conductance of the spin up channel in the magnetic tunnel junctions (MTJ)'s
+parallel (P) magnetic state that mainly accounts for an order-of-magnitude drop
+in TMR, from about 10000$\%$ in the ideal case toward values more in line with
+experiment. When placed in the middle layer of the MgO barrier, the F center
+introduces additional P $\uparrow$ transmission away from the $\Gamma$ point.
+This scattering lowers TMR to 145$\%$. In contrast, the M center merely
+broadens this transmission around $\Gamma$, thereby boosting TMR to 315$\%$.
+Rotating a M center so as to partly point along the transmission direction
+sharpens transmission around $\Gamma$, further increasing TMR to 1423$\%$. When
+these defects are placed at the MTJ interface, the transmission and ensuing
+TMR, which reaches $\approx$ 4000$\%$, suggest that such junctions behave as
+would an ideal MTJ, only with a much lower barrier height. Our results thus
+theoretically reconcile the concurrent observations of high TMR and low barrier
+heights, such as post-deposition oxidation of metallic Mg, which can generate
+oxygen vacancies at the lower MTJ interface, and annealing which can promote M
+centers over F centers.",1904.02554v1
+2019-04-04,Resonant inelastic x-ray scattering study of bond order and spin excitations in nickelate thin-film structures,"We used high-resolution resonant inelastic x-ray scattering (RIXS) at the Ni
+$L_3$ edge to simultaneously investigate high-energy interband transitions
+characteristic of Ni-O bond ordering and low-energy collective excitations of
+the Ni spins in the rare-earth nickelates $R$NiO$_3$ ($R$ = Nd, Pr, La) with
+pseudocubic perovskite structure. With the support of calculations based on a
+double-cluster model we quantify bond order (BO) amplitudes for different thin
+films and heterostructures and discriminate short-range BO fluctuations from
+long-range static order. Moreover we investigate magnetic order and exchange
+interactions in spatially confined $R$NiO$_3$ slabs by probing dispersive
+magnon excitations. While our study of superlattices (SLs) grown in the (001)
+direction of the perovskite structure reveals a robust non-collinear spin
+spiral magnetic order with dispersive magnon excitations that are essentially
+unperturbed by BO modulations and spatial confinement, we find magnons with
+flat dispersions and strongly reduced energies in SLs grown in the
+$(111)_{\text{pc}}$ direction that exhibit collinear magnetic order. These
+results give insight into the interplay of different collective ordering
+phenomena in a prototypical 3$d$ transition metal oxide and establish RIXS as a
+powerful tool to quantitatively study several order parameters and the
+corresponding collective excitations within one experiment.",1904.02782v2
+2019-04-28,Non-van der Waals honeycomb antiferromagnet SrRu$_2$O$_6$ down to a few layers,"The current family of experimentally realized two-dimensional magnetic
+materials consist of 3$d$ transition metals with very weak spin-orbit coupling.
+In contrast, we report a new platform in a chemically bonded and layered 4$d$
+oxide, with strong electron correlations and competing spin-orbit coupling. We
+synthesize ultra-thin sheets of SrRu$_2$O$_6$ using scalable liquid
+exfoliation. These exfoliated sheets are characterized by complementary
+experimental and theoretical techniques. The thickness of the nano-sheets
+varies between three to five monolayers, and within the first-principles
+calculations, we show that antiferromagnetism survives in these ultra-thin
+layers. Experimental data suggest that exfoliation occurs from the planes
+perpendicular to the $c$-axis as the intervening hexagonal Sr-lattice separates
+the two-dimensional magnetic honeycomb Ru-layers. The high-resolution
+transmission electron microscope images indicate that the average inter-atomic
+spacing between the Ru-layers is slightly reduced, which agrees with the
+present calculations. The signatures of rotational stacking of the nanosheets
+are also observed. Such new two-dimensional platform offers enormous
+possibilities to explore emergent properties that appear due to the interplay
+between magnetism, strong correlations and spin-orbit coupling. Moreover, these
+effects can be further tuned as a function of layer thickness.",1904.12326v2
+2019-11-18,Atomic-scale fragmentation and collapse of antiferromagnetic order in a doped Mott insulator,"Disentangling the relationship between the insulating state with a charge gap
+and the magnetic order in an antiferromagnetic (AF) Mott insulator remains
+difficult due to inherent phase separation as the Mott state is perturbed.
+Measuring magnetic and electronic properties at the atomic length scales would
+provide crucial insight, but this is yet to be experimentally achieved. Here we
+use spectroscopic-imaging spin-polarized scanning tunneling microscopy (SP-STM)
+to visualize periodic spin-resolved modulations originating from the AF order
+in a relativistic Mott insulator Sr2IrO4, and study these as a function of
+doping. We find that near insulator-to-metal transition (IMT), the long-range
+AF order melts into a fragmented state with short-range AF correlations.
+Crucially, we discover that the short-range AF order is locally uncorrelated
+with the observed spectral gap magnitude. This strongly suggests that short
+range AF correlations are unlikely to be the culprit behind inhomogeneous gap
+closing and the emergence of pseudogap regions near IMT. Our work establishes
+SP-STM as a powerful tool for revealing atomic-scale magnetic information in
+complex oxides.",1911.07801v1
+2019-12-10,Partial FOV Center Imaging (PCI): A Robust X-Space Image Reconstruction for Magnetic Particle Imaging,"Magnetic Particle Imaging (MPI) is an emerging medical imaging modality that
+images the spatial distribution of superparamagnetic iron oxide (SPIO)
+nanoparticles using their nonlinear response to applied magnetic fields. In
+standard x-space approach to MPI, the image is reconstructed by gridding the
+speed-compensated nanoparticle signal to the instantaneous position of the
+field free point (FFP). However, due to safety limits on the drive field, the
+field-of-view (FOV) needs to be covered by multiple relatively small partial
+field-of-views (pFOVs). The image of the entire FOV is then pieced together
+from individually processed pFOVs. These processing steps can be sensitive to
+non-ideal signal conditions such as harmonic interference, noise, and
+relaxation effects. In this work, we propose a robust x-space reconstruction
+technique, Partial FOV Center Imaging (PCI), with substantially simplified pFOV
+processing. PCI first forms a raw image of the entire FOV by mapping MPI signal
+directly to pFOV center locations. The corresponding MPI image is then obtained
+by deconvolving this raw image by a fully known, compact kernel, which solely
+depends on the pFOV size. We analyze the performance of the proposed
+reconstruction via extensive simulations, as well as imaging experiments on our
+in-house FFP MPI scanner. The results show that PCI offers a trade-off between
+noise robustness and interference robustness, outperforming standard x-space
+reconstruction in terms of both robustness against non-ideal signal conditions
+and image quality.",1912.04851v1
+2020-03-06,Assembly and disorder dissipation in superparamagnetic nanoparticle chains in a rotating magnetic field,"We investigate the formation of chains of superparamagnetic iron oxide
+nanoparticles (SPIONs) in a rotating magnetic field, combining two
+well-explored chain-forming systems: larger micron-scale beads in a rotating
+magnetic field, and SPIONs in a static field. This simple combination is
+interesting because it features self-assembly that occurs both far from
+equilibrium and at a finite temperature, with the better-explored systems
+constituting respectively its zero temperature and near-equilibrium limits.
+Theories applicable to either of the two limits qualitatively predict the chain
+length distributions, except that chains in our experiments are shorter, which
+we attribute to the simultaneous presence of thermal fluctuations and fluid
+shear forces that work in concert to break chains apart. Our most striking
+result is that the disorder in the SPION chains gradually dissipates over a
+timescale of tens of minutes, about two orders of magnitude slower than the
+characteristic chain assembly time. The disorder dissipation can be sped up by
+increasing particle concentration and solution ionic strength, both of which
+increase the speed of chain assembly. This strongly suggests that the
+improvement in chain order with time is not due to thermal fluctuations but
+rather to energy imparted by the self-assembly process, which continually
+causes chains to grow and break apart, even when a steady state distribution
+has obtained. More generally, our results indicate that self-assembly away from
+equilibrium may sometimes lead to better ordered assemblies than under
+near-equilibrium conditions.",2003.03008v2
+2020-03-29,Robust ferromagnetism in highly strained SrCoO3 thin films,"Epitaxial strain provides important pathways to control the magnetic and
+electronic states in transition metal oxides. However, the large strain is
+usually accompanied by a strong reduction of the oxygen vacancy formation
+energy, which hinders the direct manipulation of their intrinsic properties.
+Here using a post-deposition ozone annealing method, we obtained a series of
+oxygen stoichiometric SrCoO3 thin films with the tensile strain up to 3.0%. We
+observed a robust ferromagnetic ground state in all strained thin films, while
+interestingly the tensile strain triggers a distinct metal to insulator
+transition along with the increase of the tensile strain. The persistent
+ferromagnetic state across the electrical transition therefore suggests that
+the magnetic state is directly correlated with the localized electrons, rather
+than the itinerant ones, which then calls for further investigation of the
+intrinsic mechanism of this magnetic compound beyond the double-exchange
+mechanism.",2003.12982v2
+2020-09-09,Accretion disk's magnetic field controlled the composition of the terrestrial planets,"Chondrites, the building blocks of the terrestrial planets, have mass and
+atomic proportions of oxygen, iron, magnesium, and silicon totaling $\geq$90\%
+and variable Mg/Si ($\sim$25\%), Fe/Si (factor of $\geq$2), and Fe/O (factor of
+$\geq$3). The Earth and terrestrial planets (Mercury, Venus, and Mars) are
+differentiated into three layers: a metallic core, a silicate shell (mantle and
+crust), and a volatile envelope of gases, ices, and, for the Earth, liquid
+water. Each layer has different dominant elements (e.g., increasing Fe content
+with depth and increasing oxygen content to the surface). What remains an
+unknown is to what degree did physical processes during nebular disk accretion
+versus those during post-nebular disk accretion (e.g., impact erosion)
+influence these final bulk compositions. Here we predict terrestrial planet
+compositions and show that their core mass fractions and uncompressed densities
+correlate with their heliocentric distance, and follow a simple model of the
+magnetic field strength in the protoplanetary disk. Our model assesses the
+distribution of iron in terms of increasing oxidation state, aerodynamics, and
+a decreasing magnetic field strength outward from the Sun, leading to
+decreasing core size of the terrestrial planets with radial distance. This
+distribution would enhance habitability in our solar system, and would be
+equally applicable to exo-planetary systems.",2009.04311v1
+2020-09-15,Spin-orbital polarization of Majorana edge states in oxides nanowires,"We investigate a paradigmatic case of topological superconductivity in a
+one-dimensional nanowire with $d-$orbitals and a strong interplay of
+spin-orbital degrees of freedom due to the competition of orbital Rashba
+interaction, atomic spin-orbit coupling, and structural distortions. We
+demonstrate that the resulting electronic structure exhibits an orbital
+dependent magnetic anisotropy which affects the topological phase diagram and
+the character of the Majorana bound states (MBSs). The inspection of the
+electronic component of the MBSs reveals that the spin-orbital polarization
+generally occurs along the direction of the applied Zeeeman magnetic field, and
+transverse to the magnetic and orbital Rashba fields. The competition of
+symmetric and antisymmetric spin-orbit coupling remarkably leads to a
+misalignment of the spin and orbital moments transverse to the orbital Rashba
+fields, whose manifestation is essentially orbital dependent. The behavior of
+the spin-orbital polarization along the applied Zeeman field reflects the
+presence of multiple Fermi points with inequivalent orbital character in the
+normal state. Additionally, the response to variation of the electronic
+parameters related with the degree of spin-orbital entanglement leads to
+distinctive evolution of the spin-orbital polarization of the MBSs. These
+findings unveil novel paths to single-out hallmarks relevant for the
+experimental detection of MBSs.",2009.06956v1
+2020-10-17,Multiscale modelling of magnetostatic effects on magnetic nanoparticles with application to hyperthermia,"We extend a renormalization group-based course-graining method for
+micromagnetic simulations to include properly scaled magnetostatic
+interactions. We apply the method in simulations of dynamic hysteresis loops at
+clinically relevant sweep rates and at 310 K of iron oxide nanoparticles (NPs)
+of the kind that have been used in preclinical studies of magnetic
+hyperthermia. The coarse-graining method, along with a time scaling involving
+sweep rate and Gilbert damping parameter, allow us to span length scales from
+the unit cell to NPs approximately 50 nm in diameter with reasonable simulation
+times. For both NPs and the nanorods composing them, we report effective
+uniaxial anisotropy strengths and saturation magnetizations, which differ from
+those of the bulk materials magnetite and maghemite of which they are made, on
+account of the combined non-trivial effects of temperature, inter-rod exchange,
+magnetostatic interactions and the degree of orientational order within the
+nanorod composites. The effective parameters allow treating the NPs as single
+macrospins, and we find for the test case of calculating loops for two aligned
+NPs that using the dipole approximation is sufficient for distances beyond 1.5
+times the NP diameter. We also present a study on relating integration time
+step to micromagnetic cell size, finding that the optimal time step size scales
+approximately linearly with cell volume.",2010.08848v1
+2021-01-30,Colossal Magnetoresistance without Mixed Valence in a Layered Phosphide Crystal,"Materials with strong magnetoresistive responses are the backbone of
+spintronic technology, magnetic sensors, and hard drives. Among them, manganese
+oxides with a mixed valence and a cubic perovskite structure stand out due to
+their colossal magnetoresistance (CMR). A double exchange interaction underlies
+the CMR in manganates, whereby charge transport is enhanced when the spins on
+neighboring Mn3+ and Mn4+ ions are parallel. Prior efforts to find different
+materials or mechanisms for CMR resulted in a much smaller effect. Here we show
+an enormous CMR at low temperatures in EuCd2P2 without manganese, oxygen, mixed
+valence, or cubic perovskite structure. EuCd2P2 has a layered trigonal lattice
+and exhibits antiferromagnetic ordering at 11 K. The magnitude of CMR (104
+percent) in as-grown crystals of EuCd2P2 rivals the magnitude in optimized thin
+films of manganates. Our magnetization, transport, and synchrotron X-ray data
+suggest that strong magnetic fluctuations are responsible for this phenomenon.
+The realization of CMR at low temperatures without heterovalency leads to a new
+regime for materials and technologies related to antiferromagnetic spintronics.",2102.00204v1
+2021-05-26,Imaging antiferromagnetic domain fluctuations and the effect of atomic-scale disorder in a doped spin-orbit Mott insulator,"Correlated oxides can exhibit complex magnetic patterns, characterized by
+domains with vastly different size, shape and magnetic moment spanning the
+material. Understanding how magnetic domains form in the presence of chemical
+disorder and their robustness to temperature variations has been of particular
+interest, but atomic-scale insight into this problem has been limited. We use
+spin-polarized scanning tunneling microscopy to image the evolution of
+spin-resolved modulations originating from antiferromagnetic (AF) ordering in a
+spin-orbit Mott insulator Sr3Ir2O7 as a function of chemical composition and
+temperature. We find that replacing only several percent of La for Sr leaves
+behind nanometer-scale AF puddles clustering away from La substitutions
+preferentially located in the middle SrO layer within the unit cell. Thermal
+erasure and re-entry into the low-temperature ground state leads to a spatial
+reorganization of the AF modulations, indicating multiple stable AF
+configurations at low temperature. Interestingly, regardless of this
+rearrangement, the AF puddles maintain scale-invariant fractal geometry in each
+configuration. Our experiments reveal spatial fluctuations of the AF order in
+electron doped Sr3Ir2O7, and shed light on its sensitivity to different types
+of atomic-scale disorder.",2105.12648v1
+2021-08-21,Transport Spin Polarization of Noncollinear Antiferromagnetic Antiperovskites,"Spin-polarized currents play a key role in spintronics. Recently, it has been
+found that antiferromagnets with a non-spin-degenerate band structure can
+efficiently spin-polarize electric currents, even though their net
+magnetization is zero. Among the antiferromagnetic metals with magnetic space
+group symmetry supporting this functionality, the noncollinear
+antiferromagnetic antiperovskites ANMn$_3$ (A = Ga, Ni, Sn, and Pt) are
+especially promising. This is due to their high N\'eel temperatures and a good
+lattice match to perovskite oxide substrates, offering possibilities of high
+structural quality heterostructures based on these materials. Here, we
+investigate the spin polarization of antiferromagnetic ANMn$_3$ metals using
+first-principles density functional theory calculations. We find that the spin
+polarization of the longitudinal currents in these materials is comparable to
+that in widely used ferromagnetic metals, and thus can be exploited in magnetic
+tunnel junctions and spin transfer torque devices. Moreover, for certain film
+growth directions, the out-of-plane transverse spin currents with a giant
+charge-to-spin conversion efficiency can be achieved, implying that the
+ANMn$_3$ antiperovskites can be used as efficient spin sources. These
+properties make ANMn$_3$ compounds promising for application in spintronics.",2108.09540v2
+2021-08-27,An overview of the structural correlation of magnetic and electrical properties of Pr2NiMnO6 Double perovskite,"Double perovskites R2NiMnO6 (R= Rare earth element) (RNMO) are a significant
+class of materials owing to their varied tunability of the magnetic and
+electrical properties with the structural modifications. Pr2NiMnO6 (PNMO) is
+one of the least explored members of this series, which shows spin-phonon
+coupling, magnetocaloric effect, and electrochemical performance for various
+applications such as spintronics, magnetocaloric refrigerant, and solid oxide
+fuel cells. Most of the studies in PNMO are limited to the application domain
+and focus on the comparative study with different rare earth elements. Detailed
+structural studies like neutron diffraction are sparse in PNMO samples which
+will give a perception to the ordering in the compound that strongly depends on
+the physical and chemical properties. This review article goes through the
+various aspects of PNMO materials that have been reported till now and showcase
+the octahedral distortions and corresponding structural changes and the
+exchange interactions, which in turn correlates with the magnetic and
+electrical properties. The comparison study of PNMO with other members of the
+RNMO family and the relevance of PNMO over other members is also tried to
+showcase through this article. Hope this article provides an insight into the
+scope of studies in PNMO material for exploring unexposed properties of the
+materials in the double perovskite family.",2108.12498v1
+2021-09-20,Towards Non-Volatile Spin Orbit Devices: Deposition of Ferroelectric Hafnia on Monolayer Graphene/Co/HM Stacks,"Although technologically challenging, the integration of ferroelectric thin
+films with graphene spintronics potentially allows the realization of highly
+efficient, electrically tuneable, non-volatile memories. Here, the atomic layer
+deposition (ALD) of ferroelectric Hf$_{0.5}$Zr$_{0.5}$O$_2$ (HZO) directly on
+graphene (Gr)/Co/heavy metal (HM) epitaxial stacks is investigated via the
+implementation of several nucleation methods. With an in-situ method employing
+an Al$_2$O$_3$ layer, the HZO demonstrates a remanent polarization (2Pr) of
+19.2 $\mu C/cm^2$. An ex-situ, naturally oxidized sputtered Ta layer for
+nucleation produces a film with 2Pr of 10.81 $\mu C/cm^2$, but a lower coercive
+field over the stack and switching enduring over subsequent cycles. Magnetic
+hysteresis measurements taken before and after ALD deposition show strong
+perpendicular magnetic anisotropy (PMA), with only slight deviations in the
+magnetic coercive fields due to the HZO deposition process, thus pointing to a
+good preservation of the single-layer Gr. X-ray diffraction measurements
+further confirm that the high-quality interfaces demonstrated in the stack
+remain unperturbed by the ferroelectric deposition and anneal.",2109.09543v3
+2021-12-20,Spin current transport in hybrid Pt / multifunctional magnetoelectric Ga0.6Fe1.4O3 bilayers,"The low power manipulation of magnetization is currently a highly
+sought-after objective in spintronics. Non ferromagnetic large spin-orbit
+coupling heavy metal (NM) / ferromagnet (FM) heterostructures offer interesting
+elements of response to this issue, by granting the manipulation of the FM
+magnetization by the NM spin Hall effect (SHE) generated spin current.
+Additional functionalities, such as the electric field control of the spin
+current generation, can be offered using multifunctional ferromagnets. We have
+studied the spin current transfer processes between Pt and the multifunctional
+magnetoelectric Ga0.6Fe1.4O3 (GFO). In particular, via angular dependent
+magnetotransport measurements, we were able to differentiate between magnetic
+proximity effect (MPE)-induced anisotropic magnetoresistance (AMR) and spin
+Hall magnetoresistance (SMR). Our analysis shows that SMR is the dominant
+phenomenon at all temperatures and is the only one to be considered near room
+temperature, with a magnitude comparable to those observed in Pd/YIG or Pt/YIG
+heterostructures. These results indicate that magnetoelectric GFO thin films
+show promises for achieving an electric-field control of the spin current
+generation in NM/FM oxide-based heterostructures.",2112.10406v1
+2022-02-03,Thickness and temperature dependence of the atomic-scale structure of SrRuO$_3$ thin films,"Due to the strong lattice-property relationships which exist in complex oxide
+epitaxial layers, their electronic and magnetic properties can be modulated by
+structural distortions induced at the atomic scale. The modification and
+control can be affected at coherent heterointerfaces by epitaxial strain
+imposed by the substrate or by structural modifications to accommodate the
+film-substrate symmetry mismatch. Often these act in conjunction with a strong
+dependence on the layer thickness, especially for ultrathin layers. Moreover,
+as a result of these effects, the temperature dependence of the structure may
+deviate largely from that of the bulk. The temperature-dependent structure of 3
+to 44 unit cell thick ferromagnetic SrRuO$_3$ films grown on Nb-doped SrTiO$_3$
+substrates are investigated using a combination of high-resolution synchrotron
+X-ray diffraction and high-resolution electron microscopy. This aims to shed
+light on the intriguing magnetic and magnetotransport properties of epitaxial
+SRO layers, subjected to extensive investigations lately. The oxygen octahedral
+tilts and rotations are found to be strongly dependent on the temperature, the
+film thickness, and the distance away from the film-substrate interface. As a
+striking manifestation of the coupling between magnetic order and lattice
+structure, the Invar effect is observed below the ferromagnetic transition
+temperature in epitaxial layers as thin as 8 unit cells, similar to bulk
+ferromagnetic SrRuO$_3$.",2202.01652v1
+2022-03-23,Highly sensitive and high throughput magnetic resonance thermometry using superparamagnetic nanoparticles,"Magnetic resonance imaging (MRI) enables non-invasive 3D thermometry during
+thermal ablation of cancerous tumors. While T1 or T2 contrast MRI are
+relatively insensitive to temperature, techniques with greater temperature
+sensitivity such as chemical shift or diffusion imaging suffer from motional
+artifacts and long scan times. We describe an approach for highly sensitive and
+high throughput MR thermometry that is not susceptible to motional artifacts.
+We use superparamagnetic iron oxide nanoparticles (SPIONs) to spoil T2 of water
+protons. Motional narrowing results in proportionality between T2 and the
+diffusion constant, dependent only on the temperature in a specific
+environment. Our results show, for pure water, the nuclear magnetic resonance
+(NMR) linewidth and T2 follow the same temperature dependence as the
+self-diffusion constant of water. Thus, T2 mapping is a diffusion mapping in
+the presence of SPIONs, and T2 is a thermometer. For pure water, a T2 mapping
+of a 64 x 64 image (voxel size = 0.5 mm x 0.5 mm x 3 mm) in a 9.4 T MRI scanner
+resulted in a temperature resolution of 0.5 K for a scan time of 2 minutes.
+This indicates a highly sensitive and high throughput MR thermometry technique
+potentially useful for monitoring of biological tissues during thermal
+therapies or for diagnosis.",2203.12544v4
+2022-03-25,Reconciling monolayer and bilayer $J_{\rm eff} = 1/2$ square lattices in hybrid oxide superlattice,"The number of atomic layers confined in a two-dimensional structure is
+crucial for the electronic and magnetic properties. Single-layer and bilayer
+$J_{\rm eff} = 1/2$ square lattices are well-known examples where the presence
+of the extra layer turns the XY-anisotropy to the $c$-axis anisotropy. We
+report on experimental realization of a hybrid SrIrO$_3$/SrTiO$_3$ superlattice
+that integrates monolayer and bilayer square lattices in one layered structure.
+By synchrotron x-ray diffraction, resonant x-ray magnetic scattering,
+magnetization, and resistivity measurements, we found that the hybrid
+superlattice exhibits properties that are distinct from both the single-layer
+and bilayer systems and cannot be explained by a simple addition of them. In
+particular, the entire hybrid superlattice orders simultaneously through a
+single antiferromagnetic transition at temperatures similar to the bilayer
+system but with all the $J_{\rm eff} = 1/2$ moments mainly pointing in the
+$ab$-plane similar to the single-layer system. The results show that bringing
+monolayer and bilayer with orthogonal properties in proximity to each other in
+a hybrid superlattice structure is a powerful way to stabilize a unique state
+not obtainable in a uniform structure.",2203.13426v1
+2022-11-18,Synthesis of infinite-layer nickelates and influence of the capping-layer on magnetotransport,"The recent discovery of a zero-resistance state in nickel-based compounds has
+generated a re-excitement about the long-standing problem in condensed matter
+of high-critical-temperature superconductivity, in light of the analogies
+between infinite-layer nickelates and cuprates. However, despite some formal
+valence and crystal symmetry analogies, the electronic properties of
+infinite-layer nickelates are remarkably original accounting, among other
+properties, of a unique Nd5d-Ni3d hybridization. This designates infinite-layer
+nickelates as a new class of oxide superconductors which should be considered
+on their own. Here we report about Nd1-xSrxNiO2 (x = 0, 0.05 and 0.2) thin
+films synthesized with and without a SrTiO3 capping-layer, showing very smooth
+and step-terraced surface morphologies. Angle-dependent anisotropic
+magnetoresistance measurements performed with a magnetic field rotating
+in-plane or out-of-plane with respect to the sample surface, rendered important
+information about the magnetic properties of undoped SrTiO3-capped and uncapped
+samples. The results point at a key role of the capping-layer in controlling
+the magnitude and the anisotropy of the anisotropic magnetoresistance
+properties. We discuss this control in terms of a combined effect between the
+Nd-Ni hybridization and an intra-atomic exchange coupling between the Nd-4f and
+Nd-5d states, the latter essentially contributing to the (magneto)transport.
+Further studies foresee the influence of the capping layer on infinite-layer
+nickelates with no magnetic rare-earth.",2211.10251v1
+2022-12-23,Hybridization driving distortions and multiferroicity in rare-earth nickelates,"For decades transition-metal oxides have generated a huge interest due to the
+multitude of physical phenomena they exhibit. In this class of materials, the
+rare-earth nickelates, $R$NiO$_3$, stand out for their rich phase diagram
+stemming from complex couplings between the lattice, electronic and magnetic
+degrees of freedom. Here, we present a first-principles study of the
+low-temperature phase for two members of the $R$NiO$_3$ series, with $R=$ Pr,
+Y. We employ density-functional theory with Hubbard corrections accounting not
+only for the on-site localizing interactions among the Ni--$3d$ electrons
+($U$), but also the inter-site hybridization effects between the
+transition-metals and the ligands ($V$). All the \textit{U} and \textit{V}
+parameters are calculated from first-principles using density-functional
+perturbation theory, resulting in a fully \emph{ab initio} methodology. Our
+simulations show that the inclusion of the inter-site interaction parameters
+$V$ is necessary to simultaneously capture the features well-established by
+experimental characterizations of the low-temperature state: insulating
+character, antiferromagnetism and bond disproportionation. On the contrary, for
+some magnetic orderings the inclusion of on-site interaction parameters $U$
+alone completely suppresses the breathing distortion occurring in the
+low-temperature phase and produces an erroneous electronic state with a
+vanishing band gap. In addition -- only when both the \textit{U} and \textit{V}
+are considered -- we predict a polar phase with a magnetization-dependent
+electric polarization, supporting very recent experimental observations that
+suggest a possible occurrence of type-II multiferroicity for these materials.",2212.12529v1
+2023-01-04,Preparation and Characterization of NixMn0.25-xMg0.75Fe2O4 Nano-ferrite as NO2 Gas Sensing Material,"NixMn0.25-xMg0.75Fe2O4 nano-ferrites (where x = 0.00, 0.05, 0.10, 0.15 and
+0.20) were produced via sol-gel auto-combustion technique. Investigations were
+done into how the incorporation of Ni ions affects the Mn0.25Mg0.75Fe2O4
+ferrite's structure, morphological, magnetic, and NO2 gas sensing features. All
+the samples are single-phase, based on the structural study utilizing the X-ray
+diffraction (XRD) pattern. In terms of the structure of the cubic spinel,
+according to the XRD study, the crystallite sizes range from 24.30 to 28.32 nm,
+indicating nano-crystallinity. The synthesis of spherical nanoparticles with a
+small modification in particle size distribution was verified via FE-SEM
+images. The study found that the size of particles is tiny enough to act
+superparamagnetically. The area of hysteresis loop is almost non-existing, thus
+reflecting typical soft magnetic materials according to magnetic measurements
+by VSM carried out at room temperature. Furthermore, the conductance responses
+of the NixMn0.25-xMg0.75Fe2O4 nano-ferrite were measured by exposing the
+ferrite to oxidizing (NO2) gas at different operating temperatures. The results
+show that the sensor boasts shorter response and recovery times, as well as a
+higher sensitivity 707.22% of the sample (x=0.20) for nano-ferrite.",2301.01728v1
+2023-09-24,Novel one-pot sol-gel synthesis route of Fe3C/few-layered graphene core/shell nanoparticles embedded in a carbon matrix,"Fe3C/few-layered graphene core/shell nanoparticles embedded in a carbon
+matrix are synthesized by a novel two-step surfactant sol-gel strategy, where
+the processes of hydrolysis, polycondensation and drying take place in a
+one-pot. The present approach is based on the combined action of oleic acid and
+oleylamine, which act sterically on the precursor micelles when a densification
+temperature is performed in a reducing atmosphere. The structural and magnetic
+evolution of the formed compounds is investigated, ranging from iron oxides
+such as Fe3O4 and FeO, to the formation of pure Fe3C/C samples from 700 {\deg}C
+onwards. Interestingly, Fe3C nanoparticles with a size of ~20 nm crystallize
+immersed in the carbon matrix and the surrounding environment forms an oriented
+encapsulation built by few-layered graphene. The nanostructures show a
+saturation magnetization of ~43 emu/g and a moderate coercivity of ~500 Oe.
+Thereby, an innovative chemical route to produce single phase Fe3C
+nanoparticles is described, and an effective method of few-layered graphene
+passivation is proposed, yielding a product with a high magnetic response and
+high chemical stability against environmental corrosion.",2309.15858v1
+2023-11-15,Growth and Characterization of $β$-Mn Structured CoZn Thin Films,"Thin films of polycrystalline $\beta$-Mn structure CoZn have been grown on
+thermally oxidized Si substrates by co-sputtering from elemental targets
+followed by annealing. A range of films grown with variable Co deposition power
+and fixed Zn deposition power were produced, so as to vary the proportions of
+the two elements reaching the substrate, which were annealed post-growth.
+Whilst all films exhibited a (211) $\beta$-Mn structure CoZn texture in X-ray
+diffraction, transmission electron microscopy showed that the composition with
+the highest integrated intensity for that Bragg peak contained large vacancies
+and was covered by a thick ZnO cap owing to being Co-deficient overall. CoZn
+films deposited at ratios tuned to give the optimal volume fraction of
+$\beta$-Mn were continuous, with crystallites up to 200~nm in size, with a much
+thinner ZnO cap layer. Magnetic measurements show that such optimal CoZn films
+have a Curie temperature $T_\mathrm{C} \sim 420$~K and saturation magnetization
+of 120~emu/cm$^3$, properties close to those reported for bulk crystals. The
+$\beta$-Mn structure is chiral (P4$_{1}$32/P4$_{3}$32 space group) and is known
+to give rise to a Dzyaloshinkii-Moriya interaction (DMI) that stabilizes
+room-temperature skyrmions in the bulk. Our thin films are thus a potential
+materials platform, compatible with planar processing technology, for magnetic
+skyrmions arising from a bulk DMI.",2311.08824v2
+2018-10-11,Effect of thermal treatments in high purity Ar on the oxidation behavior of arc-PVD c-Al0.66Ti0.33N coatings,"The effect of temperature in high purity Ar (low oxygen partial pressure) on
+the oxidation and crystal phase evolution of c-Al0.66Ti0.33N arc-PVD coatings
+was investigated. High temperature tribology in Ar jet and adhesion behavior of
+the oxidized coating were addressed. The use of Ar protects the coating from
+the oxidation reactions and allowed to shed light into the details and paths of
+the nitride oxidation process. The c-Al0.66Ti0.33N nitrides were slightly
+oxidized in Ar even at high temperature. The surface chemistry evaluation shows
+very thin Al- and Ti-based oxide layers formation after 700C in Ar. However,
+the onset formation of the rutile TiO2 oxide was detected only after 900C and
+was clearly found by low-angle XRD diffraction after 1000C. XPS analysis of the
+oxidized samples at 800C indicated the formation of extremely thin layers
+mainly composed of mixed oxides a-Al2O3 g-Al2O3 and r-TiO2. Gradual changes in
+the chemical composition of the oxidized coatings observed at 900C clearly
+demonstrate the formation of gradient boundaries between Al-rich and Ti-rich
+oxy-nitride layers. After 1000C at least four oxides and oxi-nitrides layers
+and interlayers were found. Additionally, it is suspected that the transition
+oxide phases such as c-TiO, c-Al0.54Ti2.46O0.28N4.58, alpha-Al2TiO5 and TiOxNy
+might be precursors leading to the formation of thermodynamically stable rutile
+and alumina phases. Surface inspection after high temperature tribology in Ar
+jet showed formation of tensile cracks in the wear tracks and wear processes
+due to high size particle adhesion-abrasion and low size particle
+micro-ploughing of hard nitrides, oxi-nitrides and brittle oxide particles.
+Adhesion tests performed after high temperature tribology in Ar showed critical
+load decrease related to cohesive and adhesive damages at the contact point of
+the scratch track.",1810.05029v2
+2018-06-18,Degradation of Methylene Blue using Graphene Oxide-Tin Oxide Nanocomposite as Photocatalyst,"Environmental contamination and human exposure to dyes have dramatically
+increased over the past decades because of their increasing use in such
+industries as textiles, paper, plastics, tannery and paints. These dyes can
+cause deterioration in water quality by imparting color to the water and
+inducing the photosynthetic activity of aquatic organisms by hindering light
+penetration. Moreover, some of the dyes are considered carcinogenic and
+mutagenic for human health. Therefore, efficient treatment and removal of dyes
+from wastewater have attracted considerable attention in recent years.
+Photocatalysis, due to its mild reaction condition, high degradation, broad
+applied area and facile manipulation, is a promising method of solving
+environmental pollution problems. In this paper, we report the synthesis of
+graphene oxide-tin oxide (GO-SnO2) nanocomposite and the effectiveness of this
+composite in decolorizing Methylene Blue. Tin oxide was prepared by liquid
+phase co-precipitation method and graphene oxide-tin oxide (GOSnO2)
+nanocomposite were prepared by solution mixing method. Tin oxide (SnO2)
+nanoparticles have been ardently investigated as photocatalyst for water
+purification and environment decontamination but the photon generated electron
+and hole pair (EHP) recombination is one of the limiting factors. Graphene
+oxide-tin oxide (GO-SnO2) nanocomposite is very propitious to overcome this
+limitation for photocatalytic application. The as-synthesized graphene oxide
+(GO) and GO-SnO2 nanocomposite were characterized by X-ray Diffraction (XRD),
+Scanning Electron Microscopy (SEM), Energy Dispersive X-ray spectroscopy (EDX).
+The GO-SnO2 nanocomposite showed better photocatalytic degradation efficiency
+for Methylene Blue compared to SnO2 and Graphene oxide.
+  Keywords: Graphene Oxide(GO),Methylene Blue, Nanocomposite, Photocatalyst,
+Photodegradation, Tin Oxide(SnO2).",1806.06481v1
+2005-01-28,Transport and magnetic properties of GdBaCo_{2}O_{5+x} single crystals: A cobalt oxide with square-lattice CoO_2 planes over a wide range of electron and hole doping,"Single crystals of the layered perovskite GdBaCo_{2}O_{5+x} (GBCO) have been
+grown by the floating-zone method, and their transport, magnetic, and
+structural properties have been studied in detail over a wide range of oxygen
+contents. The obtained data are used to establish a rich phase diagram centered
+at the ""parent'' compound GdBaCo_{2}O_{5.5} -- an insulator with Co ions in the
+3+ state. An attractive feature of GBCO is that it allows a precise and
+continuous doping of CoO_{2} planes with either electrons or holes, spanning a
+wide range from the charge-ordered insulator at 50% electron doping (x=0) to
+the undoped band insulator (x=0.5), and further towards the heavily hole-doped
+metallic state. This continuous doping is clearly manifested in the behavior of
+thermoelectric power which exhibits a spectacular divergence with approaching
+x=0.5, where it reaches large absolute values and abruptly changes its sign. At
+low temperatures, the homogeneous distribution of doped carriers in GBCO
+becomes unstable, and both the magnetic and transport properties point to an
+intriguing nanoscopic phase separation. We also find that throughout the
+composition range the magnetic behavior in GBCO is governed by a delicate
+balance between ferromagnetic (FM) and antiferromagnetic (AF) interactions,
+which can be easily affected by temperature, doping, or magnetic field,
+bringing about FM-AF transitions and a giant magnetoresistance (MR) phenomenon.
+An exceptionally strong uniaxial anisotropy of the Co spins, which dramatically
+simplifies the possible spin arrangements, together with the possibility of
+continuous ambipolar doping turn GBCO into a model system for studying the
+competing magnetic interactions, nanoscopic phase separation and accompanying
+magnetoresistance phenomena.",0501706v1
+2012-07-13,Cationic vacancy induced room-temperature ferromagnetism in transparent conducting anatase Ti_{1-x}Ta_xO_2 (x~0.05) thin films,"We report room-temperature ferromagnetism in highly conducting transparent
+anatase Ti1-xTaxO2 (x~0.05) thin films grown by pulsed laser deposition on
+LaAlO3 substrates. Rutherford backscattering spectrometry (RBS), x-ray
+diffraction (XRD), proton induced x-ray emission (PIXE), x-ray absorption
+spectroscopy (XAS) and time-of-flight secondary ion mass spectrometry
+(TOF-SIMS) indicated negligible magnetic contaminants in the films. The
+presence of ferromagnetism with concomitant large carrier densities was
+determined by a combination of superconducting quantum interference device
+(SQUID) magnetometry, electrical transport measurements, soft x-ray magnetic
+circular dichroism (SXMCD), XAS, and optical magnetic circular dichroism (OMCD)
+and was supported by first-principle calculations. SXMCD and XAS measurements
+revealed a 90% contribution to ferromagnetism from the Ti ions and a 10%
+contribution from the O ions. RBS/channelling measurements show complete Ta
+substitution in the Ti sites though carrier activation was only 50% at 5% Ta
+concentration implying compensation by cationic defects. The role of Ti vacancy
+and Ti3+ was studied via XAS and x-ray photoemission spectroscopy (XPS)
+respectively. It was found that in films with strong ferromagnetism, the Ti
+vacancy signal was strong while Ti3+ signal was absent. We propose (in the
+absence of any obvious exchange mechanisms) that the localised magnetic
+moments, Ti vacancy sites, are ferromagnetically ordered by itinerant carriers.
+Cationic-defect-induced magnetism is an alternative route to ferromagnetism in
+wide-band-gap semiconducting oxides without any magnetic elements.",1207.3156v1
+2012-12-17,Magnetic field strength influence on the reactive magnetron sputter deposition of Ta2O5,"Reactive magnetron sputtering enables the deposition of various thin films to
+be used for protective as well as optical and electronic applications. However,
+progressing target erosion during sputtering results in increased magnetic
+field strengths at the target surface. Consequently, the glow discharge, the
+target poisoning, and hence the morphology, crystal structure and stoichiometry
+of the prepared thin films are influenced. Therefore, these effects were
+investigated by varying the cathode current Im between 0.50 and 1.00 A, the
+magnetic field strength B between 45 and 90 mT, and the O2/(Ar+O2) flow rate
+ratio between 0 and 100%. With increasing oxygen flow ratio a
+sub-stoichiometric TaOx oxide forms at the metallic Ta target surface which
+further transfers to a non-conductive tantalum pentoxide Ta2O5, impeding a
+stable DC glow discharge. These two transition zones (from Ta to TaOx and from
+TaOx to Ta2O5) shift to higher oxygen flow rates for increasing target
+currents. Contrary, increasing the magnetic field strength (e.g., due to
+sputter erosion) mainly shifts the TaOx to Ta2O5 transition to lower oxygen
+flow rates while marginally influencing the Ta to TaOx transition. To allow for
+a stable DC glow discharge (and to suppress the formation of non-conductive
+Ta2O5 at the target) even at a flow rate ratio of 100% either a high target
+current (Im >= 1 A) or a low magnetic field strength (B <= 60 mT) is necessary.
+These conditions are required to prepare stoichiometric and fully crystalline
+Ta2O5 films. Our investigations clearly demonstrate the importance of the
+magnetic field strength, which changes during sputter erosion, on the target
+poisoning and the resulting film quality.",1212.4089v2
+2014-08-30,"Magnetic, electrical and structural properties of the new Re-doped ruthenocuprate Ru1-xRexSr2GdCu2Oy","Despite the discovery of new superconductors classes, high-Tc oxides continue
+to be a current topic, because of their complex phase diagrams and
+doping-dependant effects (allowing one to investigate the interaction between
+orbitals), as well as structural properties such as lattice distortion and
+charge ordering, among many others. Ruthenocuprates are magnetic
+superconductors in which the magnetic transition temperature is much higher
+than the critical superconducting temperature, making them unique compounds.
+With the aim of investigating the dilution of the magnetic Ru sub-lattice, we
+proposed the synthesis of the new Ru1-xRexSr2GdCu2Oy ruthenocupratetype family,
+adapting the known two-step process (double perovskite + CuO)by directly doping
+the double perovskite, thus obtaining the new perovskite compound
+Sr2GdRu1-xRexOy, which represents a new synthesis process to the best of our
+knowledge. Our samples were structurally characterised through X-ray
+diffraction, and the patterns were analysed via Rietveld refinement. A complete
+magnetic characterisation as a function of temperature and applied field, as
+well as transport measurements were carried out. We discuss our results in the
+light of the two-lattice model for ruthenocuprates, and a relation between RuO2
+(magnetic) and CuO2 (superconductor) sublattices can clearly be observed.",1409.0152v1
+2016-02-18,Electronic and magnetic structure of epitaxial NiO/Fe$_3$O$_4$(001) heterostructures grown on MgO(001) and Nb-doped SrTiO$_3$(001),"We study the underlying chemical, electronic and magnetic properties of a
+number of magnetite based thin films. The main focus is placed onto
+NiO/Fe$_3$O$_4$(001) bilayers grown on MgO(001) and Nb-SrTiO$_3$(001)
+substrates. We compare the results with those obtained on pure Fe$_3$O$_4$(001)
+thin films. It is found that the magnetite layers are oxidized and Fe$^{3+}$
+dominates at the surfaces due to maghemite ($\gamma$-Fe$_2$O$_3$) formation,
+which decreases with increasing magnetite layer thickness. From a layer
+thickness of around 20 nm on the cationic distribution is close to that of
+stoichiometric Fe$_3$O$_4$. At the interface between NiO and Fe$_3$O$_4$ we
+find the Ni to be in a divalent valence state, with unambiguous spectral
+features in the Ni 2p core level x-ray photoelectron spectra typical for NiO.
+The formation of a significant NiFe$_2$O$_4$ interlayer can be excluded by
+means of XMCD. Magneto optical Kerr effect measurements reveal significant
+higher coercive fields compared to magnetite thin films grown on MgO(001), and
+a 45$^{\circ}$ rotated magnetic easy axis. We discuss the spin magnetic moments
+of the magnetite layers and find that the moment increases with increasing thin
+film thickness. At low thickness the NiO/Fe$_3$O$_4$ films grown on
+Nb-SrTiO$_3$ exhibits a significantly decreased spin magnetic moments. A
+thickness of 20 nm or above leads to spin magnetic moments close to that of
+bulk magnetite.",1602.05804v1
+2019-07-02,Néel-type skyrmions and their current-induced motion in van der Waals ferromagnet-based heterostructures,"Since the discovery of ferromagnetic two-dimensional (2D) van der Waals (vdW)
+crystals, significant interest on such 2D magnets has emerged, inspired by
+their appealing properties and integration with other 2D family for unique
+heterostructures. In known 2D magnets, spin-orbit coupling (SOC) stabilizes
+perpendicular magnetic anisotropy (PMA). Such a strong SOC could also lift the
+chiral degeneracy, leading to the formation of topological magnetic textures
+such as skyrmions through the Dzyaloshinskii-Moriya interaction (DMI). Here, we
+report the experimental observation of N\'eel-type chiral magnetic skyrmions
+and their lattice (SkX) formation in a vdW ferromagnet Fe3GeTe2 (FGT). We
+demonstrate the ability to drive individual skyrmion by short current pulses
+along a vdW heterostructure, FGT/h-BN, as highly required for any
+skyrmion-based spintronic device. Using first principle calculations supported
+by experiments, we unveil the origin of DMI being the interfaces with oxides,
+which then allows us to engineer vdW heterostructures for desired chiral
+states. Our finding opens the door to topological spin textures in the 2D vdW
+magnet and their potential device application.",1907.01425v4
+2019-07-18,Tuning spinterface properties in Iron/Fullerene thin films,"In ferromagnetic (FM) metal/organic semiconductor (OSC) heterostructures
+charge transfer can occur which leads to induction of magnetism in the
+non-magnetic OSC. This phenomenon has been described by the change in the
+density of states in the OSC which leads to a finite magnetic moment at the OSC
+interface and it is called the ""spinterface"". One of the main motivation in
+this field of organic spintronics is how to control the magnetic moment in the
+spinterface. In this regard, there are several open questions such as (i) which
+combination of FM and OSC can lead to more moment at the spinterface? (ii) Is
+the thickness of OSC also important? (iii) How does the spinterface moment vary
+with the FM thickness? (iv) Does the crystalline quality of the FM matters? (v)
+What is the effect of spinterface on magnetization reversal, domain structure
+and anisotropy? In this context, we have tried to answer the last three issues
+in this paper by studying Fe/C$_{60}$ bilayers of variable Fe thickness
+deposited on Si substrates. We find that both the induced moment and thickness
+of the spinterface vary proportionally with the Fe thickness. Such behavior is
+explained in terms of the growth quality of the Fe layer on the native oxide of
+the Si (100) substrate. The magnetization reversal, domain structure and
+anisotropy of these bilayer samples were studied and compared with their
+respective reference samples without having the C$_{60}$ layer. It is observed
+that the formation of spinterface leads to reduction in uniaxial anisotropy in
+Fe/C$_{60}$ on Si (100) in comparison to their reference samples.",1907.08248v1
+2019-09-30,Simultaneous individual and dipolar collective properties in binary assemblies of magnetic nanoparticles,"Applications based on aggregates of magnetic nanoparticles are becoming
+increasingly widespread, ranging from hyperthermia to magnetic recording.
+However, although some uses require a collective behavior, other need a more
+individual-like response, the conditions leading to either of these behaviors
+are still poorly understood. Here we use nanoscale-uniform binary random dense
+mixtures with different proportions of oxide magnetic nanoparticles with
+low$/$high anisotropy as a valuable tool to explore the crossover from
+individual to collective behavior. Two different anisotropy scenarios have been
+studied in two series of binary compacts: M1, comprising maghemite
+($\gamma$-Fe$_2$O$_3$) nanoparticles of different sizes (9.0 nm $/$ 11.5 nm)
+with barely a factor of 2 between their anisotropy energies and M2, mixing
+equally-sized pure maghemite (low-anisotropy) and Co-doped maghemite
+(high-anisotropy) nanoparticles with a large difference in anisotropy energy
+(ratio $>$ 8). Interestingly, while the M1 series exhibits collective behavior
+typical of strongly-coupled dipolar systems, the M2 series presents a more
+complex scenario where different magnetic properties resemble either
+""individual-like"" or ""collective"", crucially emphasizing that the collective
+character must be ascribed to specific properties and not to the system as a
+whole. The strong differences between the two series, offer new insight
+(systematically ratified by simulations) into the subtle interplay between
+dipolar interactions, local anisotropy and sample heterogeneity, to determine
+the behavior of dense assemblies of magnetic nanoparticles.",1909.13500v1
+2020-02-05,Magnetic Induction in Convecting Galilean Oceans,"To date, analyses of magnetic induction in putative oceans in Jupiter's large
+icy moons have assumed uniform conductivity in the modeled oceans. However, the
+phase and amplitude response of the induced fields will be influenced by the
+increasing electrical conductivity along oceans' convective adiabatic
+temperature profiles. Here, we examine the amplitudes and phase lags for
+magnetic diffusion in modeled oceans of Europa, Ganymede, and Callisto. We
+restrict our analysis to spherically symmetric configurations, treating
+interior structures based on self-consistent thermodynamics, which account for
+variations in electrical conductivity with depth in convective oceans (Vance et
+al., 2018). The numerical approach considers tens of radial layers. The
+induction response of the adiabatic conductivity profile differs from oceans
+with uniform conductivity based on the ice-ocean interface or the mean value of
+the adiabatic profile by more than 10% in many cases. In addition, we consider
+the generation of induced magnetic fields by oceanic fluid motions that might
+be used to probe the ocean flows directly (e.g., Chave, 1983; Tyler, 2011;
+Minami, 2017). Assuming turbulent convection (Soderlund et al., 2014), we find
+that these signals can dominate induction signal at low latitudes, which
+underscores the need for spatial coverage in magnetic induction investigations.
+Based on end-member ocean compositions (Zolotov, 2008; Zolotov & Kargel, 2009),
+we quantify the residual magnetic induction signals that might be used to infer
+the oxidation state of Europa's ocean and to investigate stable liquids within
+and under high-pressure ices in Ganymede and Callisto. Fully exploring this
+parameter space for the sake of planned missions requires electrical
+conductivity measurements in fluids at low temperature and to high salinity and
+pressure.",2002.01636v3
+2020-02-26,Magneto-Stark and Zeeman effect as origin of second harmonic generation of excitons in Cu$_2$O,"We report on the experimental and theoretical investigation of
+magnetic-field-induced second harmonic generation (SHG) and two-photon
+absorption (TPA) of excited exciton states ($n \geq 3$) of the yellow series in
+Cu$_2$O. In this centrosymmetric material, SHG can occur due to constructive
+interplay of electric dipole and electric quadrupole/magnetic dipole
+transitions for light propagating along the low-symmetry directions [111] or
+[112]. By application of a magnetic field in Voigt configuration, SHG gets also
+allowed for excitation along the [110]-axis and even the high-symmetry cubic
+direction [001]. Combining a symmetry analysis and a microscopic theory, we
+uncover the two key contributions to the magnetic-field-induced SHG: the Zeeman
+effect and the magneto-Stark effect. We demonstrate systematic dependencies of
+the SHG intensity on the linear polarization angles of the ingoing fundamental
+laser and the outgoing SHG beam. In general, the resulting contour plots in
+combination with a symmetry analysis allow one to determine uniquely the
+character of involved transitions. Moreover, we can separate in magnetic field
+the Zeeman and the magneto-Stark effect through appropriate choice of the
+experimental geometry and polarization configuration. We present a microscopic
+theory of the second harmonic generation of excitons in a centrosymmetric cubic
+semiconductor taking into account the symmetry and the band structure of
+cuprous oxide. Based on the developed microscopic theory we identify the main
+contributions to the second-order nonlinear susceptibility of $S$-, $P$- and
+$D$-excitons. We analyze the redistribution of SHG intensities between the
+excitonic states both in the absence and presence of the magnetic field and
+show good agreement with the experimental data. With increasing exciton
+principal quantum number the magneto-Stark effect overpowers the influence of
+the Zeeman effect.",2002.11560v1
+2019-04-18,"Probing the Griffiths like phase, unconventional dual glassy states, giant exchange bias effects and its correlation with its electronic structure in Pr2-xSrxCoMnO6","Electronic structure, electrical transport, dc and ac magnetization
+properties of the hole substituted (Sr2+) partially B-site disordered double
+perovskite Pr2-xSrxCoMnO6 system have been investigated. Electronic structure
+was probed by employing X-ray photoemission spectroscopy (XPS) measurements.
+The study suggested the presence of mixed valence states of the B-site ions
+(Co2+/Co3+ and Mn3+/Mn4+) with significant enhancement of the average oxidation
+states due to hole doping. The mere absence of electronic states near the Fermi
+level in the valence band (VB) spectra for both of the pure (x=0.0) and Sr
+doped (x=0.5) systems indicated the insulating nature of the samples. Sr
+substitution is observed to increase the spectral weight near the Fermi level
+suggesting for an enhanced conductivity of the hole doped system. The
+temperature variation of electrical resistivity measurements revealed the
+insulating nature for both the systems, thus supporting the VB spectra results.
+The dc magnetization data divulged a Griffiths like phase above the long range
+ordering temperature. A typical re-entrant spin glass like phase driven by the
+inherent anti-site disorder (ASD) has been maidenly recognized by ac
+susceptibility study for both the pure and doped systems. Most interestingly,
+the emergence of a new cluster glass like phase (immediately below the magnetic
+ordering temperature and above the spin-glass transition temperature) solely
+driven by the Sr substitution has been unravelled by ac magnetization dynamics
+study. The isothermal magnetization measurements further probed the exhibition
+of the giant exchange bias effect emanated from the existence of multiple
+magnetic phases.",1904.08817v2
+2019-08-16,"Evolution of electronic and magnetic properties in a series of iridate double perovskites Pr$_{2-x}$Sr$_x$MgIrO$_6$ ($x$ = 0, 0.5, 1.0)","Spin-orbit coupling (SOC) plays a crucial role in magnetic and electronic
+properties of 5$d$ iridates. In this paper we have experimentally investigated
+the structural and physical properties of a series of Ir-based double
+perovskite compounds Pr$_{2-x}$Sr$_x$MgIrO$_6$ ($x$ = 0, 0.5, 1; hereafter
+abbreviated as PMIO, PSMIO1505, and PSMIO). Interestingly, these compounds have
+recently been proposed to undergo a transition from the spin-orbit-coupled Mott
+insulating phase at $x$ = 0 to the elusive half-metallic antiferromagnetic
+(HMAFM) state with Sr doping at $x$ = 1. However, our detailed magnetic and
+electrical measurements refute any kind of HMAFM possibility in either of the
+doped samples. In addition, we establish that within these
+Pr$_{2-x}$Sr$_x$MgIrO$_6$ double perovskites, changes in Ir-oxidation states
+(4+ for PMIO to 5+ for PSMIO via mixed 4+/5+ for PSMIO1505) lead to markedly
+different magnetic behaviors. While SOC on Ir is at the root of the observed
+insulating behaviors for all three samples, the correlated magnetic properties
+of these three compounds develop entirely due to the contribution from local Ir
+moments. Additionally, the magnetic Pr$^{3+}$ (4$f^2$) ions, instead of showing
+any kind of ordering, only contribute to the total paramagnetic moment. It is
+seen that the PrSrMgIrO$_6$ sample does not order down to 2 K despite
+antiferromagnetic interactions. But, the $d^5$ iridate Pr$_2$MgIrO$_6$ shows a
+sharp antiferromagnetic (AFM) transition at around 14 K, and in the mixed
+valent Pr$_{1.5}$Sr$_{0.5}$MgIrO$_6$ sample the AFM transition is shifted to a
+much lower temperature ($\sim$ 6 K) due to weakening of the AFM exchange.",1908.05973v1
+2020-05-19,The benefits of a Bayesian analysis for the characterization of magnetic nanoparticles,"Magnetic nanoparticles offer a unique potential for various biomedical
+applications, but prior to commercial usage a standardized characterization of
+their structural and magnetic properties is required. For a thorough
+characterization, the combination of conventional magnetometry and advanced
+scattering techniques has shown great potential. In the present work, we
+characterize a powder sample of high-quality iron oxide nanoparticles that are
+surrounded with a homogeneous thick silica shell by DC magnetometry and
+magnetic small-angle neutron scattering (SANS). To retrieve the particle
+parameters such as their size distribution and saturation magnetization from
+the data, we apply standard model fits of individual data sets as well as
+global fits of multiple curves, including a combination of the magnetometry and
+SANS measurements. We show that by combining a standard least-squares fit with
+a subsequent Bayesian approach for the data refinement, the probability
+distributions of the model parameters and their cross correlations can be
+readily extracted, which enables a direct visual feedback regarding the quality
+of the fit. This prevents an overfitting of data in case of highly correlated
+parameters and renders the Bayesian method as an ideal component for a
+standardized data analysis of magnetic nanoparticle samples.",2005.09325v3
+2021-03-09,Tuning the tilting of the spiral plane by Mn doping in YBaCuFeO5 multiferroic,"The layered perovskite YBaCuFeO5 (YBCFO) is considered one of the best
+candidates to high-temperature chiral multiferroics with strong magnetoelectric
+coupling. In RBaCuFeO5 perovskites (R: rare-earth or Y) A-site cations are
+fully ordered whereas their magnetic properties strongly depend on the
+preparation process. They exhibit partial cationic disorder at the B-site that
+generates a magnetic spiral stabilized through directionally assisted long
+range coupling between canted locally frustrated spins. Moreover the
+orientation of its magnetic spiral can be critical for the magnetoelectric
+response of this chiral magnetic oxide. We have synthesized and studied
+YBaCuFe1-xMnxO5 samples doped with Mn, with the aim of increasing spin-orbit
+coupling effects, and found that the overall Fe/Cu cation disorder at the
+B-sites can be increased by doping without changing the sample preparation
+process. In YBaCuFe1-xMnxO5 samples prepared under the same conditions, the T-x
+magnetic phase diagram have been constructed in the range 10K-500K combining
+magnetometry, X-ray and neutron powder diffraction measurements. The tilting
+angles of the spins in the collinear, {\theta}col , and spiral phases,
+{\theta}spiral, barely vary with temperature. In the collinear phase
+{\theta}col is also independent of the Mn content. In contrast, the presence of
+Mn produces a progressive reorientation of the plane of the magnetic helix in
+the incommensurate phase, capable to transform the helicoidal spin ordering
+into a cycloidal one, which may critically determine the ferroelectric and
+magnetoelectric behavior in these compounds. Some of the observations are of
+interest for engineering and developing this family of potential
+high-temperature multiferroics.",2103.05540v1
+2023-03-14,The rise and fall of Mott insulating gaps in YNiO$_3$ paramagnets as a reflection of symmetry breaking and remaking,"The YNiO$_3$ nickelate is a paradigm d-electron oxide that manifests the
+intriguing temperature-mediated sequence of three phases transitions from (i)
+magnetically ordered insulator to (ii) paramagnetic (PM) insulator and then to
+(iii) PM metal. Such phenomena raised the question of the nature of the
+association of magnetism and structural symmetry breaking with the appearance
+in (i) and (ii) and disappearance in (iii) of insulating band gaps. It is
+demonstrated here that first-principles mean-field-like density functional
+theory (DFT), driven by molecular dynamics temperature evolution, can describe
+not only the origin of the magnetically long-range ordered insulating phase
+(i), but also the creation of an insulating paramagnet (ii) that lacks
+spin-long-range order, and of a metallic paramagnet (iii) as temperature rises.
+This approach provides the patterns of structural and magnetic symmetry
+breaking at different temperatures, in parallel with band gaps obtained when
+the evolving geometries are used as input to DFT electronic band structure
+calculations. This disentangles the complex interplay among spin, charge and
+orbital degrees of freedom. Analysis shows that the success in describing the
+rise and fall of the insulating band gaps along the phase transition sequence
+is enabled by allowing sufficient flexibility in describing diverse local
+structural and magnetic motifs as input to DFT. This entails using sufficiently
+large supercells that allow expressing structural disproportionation of
+octahedra, as well as a description of PM phases as a distribution of local
+magnetic moments. It appears that the historic dismissal of mean-field-like DFT
+as being unable to describe such Mott-like transitions was premature, as it was
+based on consideration of averaged crystallographic unit cells, a description
+that washes out local symmetry-breaking motifs.",2303.08199v1
+2009-12-31,Novel Structural Motifs in Oxidized Graphene,"The structural and electronic properties of oxidized graphene are
+investigated on the basis of the genetic algorithm and density functional
+theory calculations. We find two new low energy semiconducting phases of the
+fully oxidized graphene (C1O). In one phase, there is parallel epoxy pair
+chains running along the zigzag direction. In contrast, the ground state phase
+with a slightly lower energy and a much larger band gap contains epoxy groups
+in three different ways: normal epoxy, unzipped epoxy, and epoxy pair. For
+partially oxidized graphene, a phase separation between bare graphene and fully
+oxidized graphene is predicted.",1001.0171v1
+2012-07-31,Ge condensation under SiGe oxidization: from Molecular Dynamics simulation to one-dimensional analytic modeling,"Oxidization of a dilute Si(Ge) alloy is modeled using an original protocol
+based on molecular dynamics simulation and rules for the oxygen insertions.
+These rules, deduced from ab-initio calculations, favor the formation of SiO_2
+against GeO_2 oxide which leads to segregation of Ge atoms into the alloy
+during the oxidization front advance. Ge condensation is then observed close to
+the SiO_2/Ge interface due to the strain induced by oxydization in this region.
+From the analysis of the simulation process, we propose a one-dimensional
+description of Ge condensation wich perfectly reproduces the evolution of the
+Ge concentration during oxidization of the SiGe alloy.",1207.7238v1
+2015-11-24,Structural Properties and Thermodynamics of Hafnium sub-oxides in RRAM,"We study the structural and electronic properties of various hafnium
+sub-oxides HfzO from z = 9 to z = 0.5, by ab initio simulation using Density
+Functional Theory. The stability of these sub-oxides is studied against
+monoclinic HfO2. The progressive oxidation of a given HfzO is also envisaged
+toward stoichiometric HfO2. The analogy with a conductive region of electrons
+inside a HfO2 matrix is discussed within the context of Oxide-based Resistive
+Random Access Memories (OxRRAM) devices which employ hafnium dioxide as an
+insulator.",1511.07665v1
+2016-02-26,Epitaxially Stabilized Oxide Composed of Twisted Triangular-Lattice Layers,"Layered oxides have been intensively studied due to their high designability
+for various electronic functions. Here we synthesize a new oxide as epitaxial
+thin film form by pulsed laser deposition. Film characterizations including
+cross-section and plan-view transmission electron microscopy confirm that the
+film is composed of twisted stack of triangular-lattice Rh and Bi layers. We
+foresee that the concept of twisted oxide layers will open up a new route to
+design further functional layered oxides.",1602.08192v1
+2016-10-31,Buffer Layer Engineering on Graphene via Various Oxidation Methods for Atomic Layer Deposition,"The integration of high-k oxide on graphene using atomic layer deposition
+requires an electrically reliable buffer layer. In this study, Y was selected
+as the buffer layer due to the highest oxidation ability in rare earth elements
+and various oxidation methods (atmospheric, high-pressure O2 and ozone) were
+applied to the Y metal buffer layer. By optimizing oxidation conditions of the
+top gate insulator, we successfully improve the capacitance of top gate Y2O3
+insulator and demonstrate a large Ion/Ioff ratio for bilayer graphene under an
+external electric field.",1610.09857v1
+2020-01-08,Electrical and optical properties of hydrated amorphous vanadium oxide,"Electrical and optical properties of amorphous vanadium oxide thin films
+obtained by electrochemical anodic oxidation are studied. It is shown that
+under cathodic polarization the hydrogen insertion into vanadium oxide from an
+electrolyte occurs. Metal-insulator transition in amorphous HxVO2 is found to
+be preserved up to high concentration (x ~ 1.5) of hydrogen. Memory switching
+with the N-type negative differential resistance, associated with the H+ ionic
+transfer, is observed in ""V/hydrated amorphous vanadium oxide/Au"" sandwich
+structures.",2001.02418v1
+2020-09-25,Current progress in vanadium oxide nanostructures and its composites as supercapacitor electrodes,"In recent years, vanadium oxides have gained immense attention in the field
+of energy storage devices due to their low-cost, layered structure and
+multi-valency despite their limited electrical conductivity and lower
+structural stability. In this brief review, we have tried to focus on
+electrochemical properties of the stoichiometric vanadium oxides along with
+VO_x composites. The morphology engineering, doping with heteroatom and
+formation of composites with carbon-based materials and/or conducting polymers
+in enhancing the supercapacitive performances of the vanadium oxides are
+discussed in details. Finally, the potentiality and challenges of vanadium
+oxides nanocomposites for supercapacitor applications are discussed.",2009.12034v1
+2021-02-23,Structure and hardness of in situ synthesized nano-oxide strengthened CoCrFeNi high entropy alloy thin films,"In this study, we report on face-centered cubic structured CoCrFeNi
+high-entropy alloy thin films with finely dispersed nano-oxide particles which
+are formed by internal oxidation. Analytical scanning transmission electron
+microscopy imaging found that the particles are Cr2O3. The oxide particles
+contribute to the hardening of the film increasing its hardness by 14% compared
+to that of the film without precipitates, through the Orowan-type strengthening
+mechanism. Our novel approach paves the way to design medium- and high-entropy
+alloys with high strength by making use of oxide phases.",2102.11950v1
+2011-09-02,A first-principles study of helium storage in oxides and at oxide--iron interfaces,"Density-functional theory calculations based on conventional as well as
+hybrid exchange-correlation functionals have been carried out to study the
+properties of helium in various oxides (Al2O3, TiO2, Y2O3, YAP, YAG, YAM, MgO,
+CaO, BaO, SrO) as well as at oxide-iron interfaces. Helium interstitials in
+bulk oxides are shown to be energetically more favorable than substitutional
+helium, yet helium binds to existing vacancies. The solubility of He in oxides
+is systematically higher than in iron and scales with the free volume at the
+interstitial site nearly independently of the chemical composition of the
+oxide. In most oxides He migration is significantly slower and He--He binding
+is much weaker than in iron. To quantify the solubility of helium at oxide-iron
+interfaces two prototypical systems are considered (Fe|MgO, Fe|FeO|MgO). In
+both cases the He solubility is markedly enhanced in the interface compared to
+either of the bulk phases. The results of the calculations allow to construct a
+schematic energy landscape for He interstitials in iron. The implications of
+these results are discussed in the context of helium sequestration in oxide
+dispersion strengthened steels, including the effects of interfaces and lattice
+strain.",1109.0433v2
+2015-06-26,Influence of van der Waals interactions on morphology and dynamics in ultrathin liquid films at silicon oxide interfaces,"Single molecule tracer diffusion studies of evaporating (thinning) ultrathin
+tetrakis-2-ethyl-hexoxysilane (TEHOS) films on silicon with 100 nm thermal
+oxide reveal a considerable slowdown of the molecular mobility within less than
+4 nm above the substrate (corresponding to a few molecular TEHOS layers). This
+is related to restricted mobility and structure formation of the liquid in this
+region, in agreement with information obtained from a long-time ellipsometric
+study of thinning TEHOS films on silicon substrates with 100 nm thermal or 2 nm
+native oxide. Both show evidence for the formation of up to four layers.
+Additionally, on thermal oxide, a lateral flow of the liquid is observed, while
+the film on the native oxide forms an almost flat surface and shows negligible
+flow. Thus, on the 2 nm native oxide the liquid mobility is even more
+restricted in close vicinity to the substrate as compared to the 100 nm thermal
+oxide. In addition, we found a significantly smaller initial film thickness in
+case of the native oxide under similar dipcoating conditions. We ascribe these
+differences to van der Waals interactions with the underlying silicon in case
+of the native oxide, whereas the thermal oxide suffices to shield those
+interactions.",1506.08144v1
+2016-04-21,Superconductivity in the antiperovskite Dirac-metal oxide Sr$_3$SnO,"Oxides with perovskite-based structures have been known as essential
+materials for fascinating phenomena such as high-temperature and unconventional
+superconductivity. Discoveries of these oxide superconductors have driven the
+science community to vastly extend the concepts of strongly correlated electron
+systems. The base of these materials, the cubic perovskite oxides, $AB$O$_3$,
+also exhibit superconductivity with $T_{\mathrm{c}}$ of up to 30 K, as reported
+for Ba$_{0.6}$K$_{0.4}$BiO$_3$. Perovskite oxides have their counterparts,
+antiperovskite oxides $A_3B$O (or ""$B$O$A_3$""), in which the position of metal
+and oxygen ions are reversed and therefore metallic $B$ ions take unusual
+negative valence states. However, no superconductivity has been reported among
+antiperovskite oxides. Here, we report the discovery of the first
+superconducting antiperovskite oxide Sr$_3$SnO with $T_{\mathrm{c}}$ of around
+5 K. Sr$_3$SnO possesses Dirac points in its electronic structure, originating
+from the inversion of bands with different parities. Based on theoretical
+analysis, we propose possibility of topological odd-parity superconductivity
+analogous to the superfluid $^3$He-B, in moderately hole-doped Sr$_3$SnO,
+originating from unusual orbital texture on the Fermi surface. We envision that
+this discovery of a new class of oxide superconductor with the inverted valence
+configuration will stimulate the exploration of topological materials science
+based on a variety of antiperovskite oxides.",1604.06238v2
+2014-03-10,Ethylene oxide and Acetaldehyde in hot cores,"[Abridged] Ethylene oxide and its isomer acetaldehyde are important complex
+organic molecules because of their potential role in the formation of amino
+acids. Despite the fact that acetaldehyde is ubiquitous in the interstellar
+medium, ethylene oxide has not yet been detected in cold sources. We aim to
+understand the chemistry of the formation and loss of ethylene oxide in hot and
+cold interstellar objects (i) by including in a revised gas-grain network some
+recent experimental results on grain surfaces and (ii) by comparison with the
+chemical behaviour of its isomer, acetaldehyde. We test the code for the case
+of a hot core. The model allows us to predict the gaseous and solid ethylene
+oxide abundances during a cooling-down phase prior to star formation and during
+the subsequent warm-up phase. We can therefore predict at what temperatures
+ethylene oxide forms on grain surfaces and at what temperature it starts to
+desorb into the gas phase. The model reproduces the observed gaseous abundances
+of ethylene oxide and acetaldehyde towards high-mass star-forming regions. In
+addition, our results show that ethylene oxide may be present in outer and
+cooler regions of hot cores where its isomer has already been detected. Despite
+their different chemical structures, the chemistry of ethylene oxide is coupled
+to that of acetaldehyde, suggesting that acetaldehyde may be used as a tracer
+for ethylene oxide towards cold cores.",1403.2355v1
+2018-09-25,Evaluating transition-metal oxides within DFT-SCAN and SCAN+U frameworks for solar thermochemical applications,"Using the strongly constrained and appropriately normed (SCAN) and SCAN+U
+approximations for describing electron exchange-correlation (XC) within density
+functional theory, we investigate the oxidation energetics, lattice constants,
+and electronic structure of binary Ce-, Mn-, and Fe-oxides, which are crucial
+ingredients for generating renewable fuels using two-step, oxide-based, solar
+thermochemical reactors. Unlike other common XC functionals, we find that SCAN
+does not over-bind the O2 molecule, based on direct calculations of its bond
+energy and robust agreement between calculated formation enthalpies of main
+group oxides versus experiments. However, in the case of transition-metal
+oxides (TMOs), SCAN systematically overestimates (i.e., yields too negative)
+oxidation enthalpies due to remaining self-interaction errors in the
+description of their ground-state electronic structure. Adding a Hubbard U term
+to the transition-metal centers, where the magnitude of U is determined from
+experimental oxidation enthalpies, significantly improves the qualitative
+agreement and marginally improves the quantitative agreement of
+SCAN+U-calculated electronic structure and lattice parameters, respectively,
+with experiments. Importantly, SCAN predicts the wrong ground-state structure
+for a few oxides, namely, Ce2O3, Mn2O3, and Fe3O4, while SCAN+U predicts the
+right polymorph for all systems considered in this work. Hence, the SCAN+U
+framework, with an appropriately determined U, will be required to accurately
+describe ground-state properties and yield qualitatively consistent electronic
+properties for most transition- metal and rare earth oxides.",1809.09713v1
+2018-10-11,Factors controlling oxygen interstitial diffusion in the Ruddlesden-Popper oxide La2-xSrxNiO4+delta,"The development of Ruddlesden-Popper (RP) oxides as oxygen exchange and
+transport materials will benefit from mechanistic understanding of how oxygen
+transports through these materials. Using Density Functional Theory, we found
+there are two distinct oxygen interstitial diffusion mechanisms involving two
+different oxygen interstitial species that can be active in La2-xSrxNiO4+delta,
+and, we believe, in hyperstoichiometric RP oxides in general. The first
+mechanism is the previously proposed interstitialcy-mediated mechanism, which
+consists of diffusing oxide interstitials. The second mechanism is newly
+discovered in this work, and consists of both oxide and peroxide interstitial
+species. This mechanism exhibits a similar or possibly lower migration barrier
+than the interstitialcy mechanism for high oxidation states. Which mechanism
+contributes to the oxygen interstitial diffusion is the result of the change in
+relative stability between the oxide interstitial and peroxide interstitial.
+The stability of the oxide and peroxide, and the competition between the two
+oxygen diffusion mechanisms, is sensitive to the overall oxidation state of the
+system. Therefore, the oxygen diffusion mechanism is a function of the material
+composition, oxygen off-stoichiometry, operating temperature and oxygen partial
+pressure. We also examined the effect of epitaxial strain on both oxygen
+diffusion mechanisms, and found that tensile and compressive epitaxial strain
+of up to 2% had less than 100 meV/(% strain) effects on oxygen interstitial
+formation, migration, and activation energies, and that total achievable
+activation energy reductions are likely less than 100 meV for -2% to +2%
+epitaxial strain. The presented understanding of factors governing interstitial
+oxygen diffusion has significant implications for the engineering of RP oxides
+in numerous alternative energy technologies.",1810.05209v1
+2018-12-31,Diffusion- Migration-Reaction-Limited Aggregation of Point Defects: A Model for the Stability of Oxide-layers on Metals and Its Breakdown,"A thin oxide layer protects metals from electrochemical corrosion and hence
+the stability of this oxide layer is crucial for corrosion resistance of
+metals. The dynamics of cationic and anionic point defects which are injected
+into this oxide layer at the metal-oxide-layer interface and the
+oxide-layer-environment interface during electrochemical processes determine
+the stability of this oxide-layer.
+  The point defect model originally advanced by Digby Macdonald and perfected
+into a correct and complete theory by Bosco Emmanuel provides a concrete basis
+for investigating this stability question. We have formulated a system of 3
+coupled differential equations (2 PDEs and one ODE) with appropriate initial
+and boundary conditions that include the defect injection reactions. This
+system of equations recognize the diffusion, migration and clustering of the
+point defects in the oxide-layer. The defect clustering is modelled using the
+Avrami Theorem and the area-volume laws for random agglomerates.
+  This research is expected to provide insights into the criticality associated
+with the oxide-layer breakdown and the periodic, aperiodic and chaotic
+oscillations in the electrical current / potential which signal the breakdown
+of the passive oxide-layer. A large body of experimental data is waiting to be
+understood within a frame-work such as the present. Some initial results from
+the model are also reported.",1812.11807v1
+2021-02-18,Crystal orientation-dependent oxidation of epitaxial TiN films with tunable plasmonics,"Titanium nitride (TiN) is a paradigm of refractory transition metal nitrides
+with great potential in vast applications. Generally, the plasmonic performance
+of TiN can be tuned by oxidation, which was thought to be only temperature-,
+oxygen partial pressure-, and time-dependent. Regarding the role of
+crystallographic orientation in the oxidation and resultant optical properties
+of TiN films, little is known thus far. Here we reveal that both the oxidation
+resistance behavior and the plasmonic performance of epitaxial TiN films follow
+the order of (001) < (110) < (111). The effects of crystallographic orientation
+on the lattice constants, optical properties, and oxidation levels of epitaxial
+TiN films have been systematically studied by combined high-resolution X-ray
+diffraction, spectroscopic ellipsometry, X-ray absorption spectroscopy, and
+X-ray photoemission spectroscopy. To further understand the role of
+crystallographic orientation in the initial oxidation process of TiN films,
+density-functional-theory calculations are carried out, indicating the energy
+cost of oxidation is (001) < (110) < (111), consistent with the experiments.
+The superior endurance of the (111) orientation against mild oxidation can
+largely alleviate the previously stringent technical requirements for the
+growth of TiN films with high plasmonic performance. The crystallographic
+orientation can also offer an effective controlling parameter to design
+TiN-based plasmonic devices with desired peculiarity, e.g., superior chemical
+stability against mild oxidation or large optical tunability upon oxidation.",2102.09126v1
+2023-07-02,Optoelectronic properties of silver doped copper oxide thin films,"Thin films have found a wide variety of applications because of the
+substantial improvement in their properties as compared to bulk metals. Metal
+oxide thin films are increasingly being used in various fields and are
+especially important in functional applications. They can be either p- or
+n-type in nature depending on the materials, dopants, and preparation route.
+Copper oxide is an example of a p-type metal oxide, which finds application in
+solar cells, photo-electrochemical cells, gas sensors, supercapacitors, and
+thermoelectric touch detectors. Both copper (I) and copper (II) oxides can be
+grown with the lower valence state oxide stable at low temperature and the
+higher valence state obtained by annealing at higher temperatures. In this
+work, we modify the optical and electrical properties of copper oxide thin
+films, by doping of silver through a thermal evaporation process route. Copper
+is thermally evaporated onto the substrate and silver is co-evaporated during
+this process. The films are then annealed in ambient under various conditions
+to obtain copper oxide. Structural and functional comparison is made between
+undoped and silver doped copper oxide thin films, prepared under the same
+conditions. Thermal evaporation is a simple route for obtaining doped metal
+oxides and the process can be extended to a variety of other systems as well.",2307.13649v1
+1993-11-05,Correlated Electrons in High Temperature Superconductors,"Theoretical ideas and experimental results concerning high temperature
+superconductors are reviewed. Special emphasis is given to calculations carried
+out with the help of computers applied to models of strongly correlated
+electrons proposed to describe the two dimensional ${\rm Cu O_2}$ planes. The
+review also includes results using several analytical techniques. The one and
+three band Hubbard models, and the ${\rm t-J}$ model are discussed, and their
+behavior compared against experiments when available. Among the conclusions of
+the review, we found that some experimentally observed unusual properties of
+the cuprates have a natural explanation through Hubbard-like models. In
+particular abnormal features like the mid-infrared band of the optical
+conductivity $\sigma(\omega)$, the new states observed in the gap in
+photoemission experiments, the behavior of the spin correlations with doping,
+and the presence of phase separation in the copper oxide superconductors may be
+explained, at least in part, by these models. Finally, the existence of
+superconductivity in Hubbard-like models is analyzed. Some aspects of the
+recently proposed ideas to describe the cuprates as having a $\dx2y2$
+superconducting condensate at low temperatures are discussed. Numerical results
+favor this scenario over others....(continues).",9311013v1
+1995-01-06,Non-magnetic impurities in two dimensional superconductors,"A numerical approach to disordered 2D superconductors described by BCS mean
+field theory is outlined. The energy gap and the superfluid density at zero
+temperature and the quasiparticle density of states are studied. The method
+involves approximate self-consistent solutions of the Bogolubov-de$\,$Gennes
+equations on finite square lattices. Where comparison is possible, the results
+of standard analytic approaches to this problem are reproduced. Detailed
+modeling of impurity effects is practical using this approach. The {\it range}
+of the impurity potential is shown to be of {\it quantitative importance} in
+the case of strong potential scatterers. We discuss the implications for
+experiments, such as the rapid suppression of superconductivity by Zn doping in
+Copper-Oxide superconductors.",9501016v1
+1996-06-09,NiO Exchange Bias Layers Grown by Direct Ion Beam Sputtering of a Nickel Oxide Target,"A new process for fabricating NiO exchange bias layers has been developed.
+The process involves the direct ion beam sputtering (IBS) of a NiO target. The
+process is simpler than other deposition techniques for producing NiO buffer
+layers, and facilitates the deposition of an entire spin-valve layered
+structure using IBS without breaking vacuum. The layer thickness and
+temperature dependence of the exchange field for NiO/NiFe films produced using
+IBS are presented and are similar to those reported for similar films deposited
+using reactive magnetron sputtering. The magnetic properties of highly textured
+exchange couples deposited on single crystal substrates are compared to those
+of simultaneously deposited polycrystalline films, and both show comparable
+exchange fields. These results are compared to current theories describing the
+exchange coupling at the NiO/NiFe interface.",9606052v1
+1996-12-10,A scenario for the electronic state in the manganase perovskites: the orbital correlated metal,"We argue that, at low temperatures and well into the ferromagnetic phase, the
+physics of the manganase perovskites may be characterized by a correlated
+metallic state near a metal insulator transition where the orbital degrees of
+freedom play a main role. This follows from the observation that a two-band
+degenerate Hubbard model under a strong magnetic field can be mapped onto a
+para-orbital single band model. We solve the model numerically using the
+quantum Monte Carlo technique within a dynamical mean field theory which is
+exact in the limit of large lattice connectivity. We argue that the proposed
+scenario may allow for the qualitative interpretation of a variety of
+experiments which were also observed in other (early) transition metal oxides.",9612089v2
+1997-05-01,Less than 50% sublattice polarization in an insulating S=3/2 kagome' antiferromagnet at low T,"We have found weak long range antiferromagnetic order in the
+quasi-two-dimensional insulating oxide $ KCr_3(OD)_6(SO_4)_2$ which contains
+Cr$^{3+}$ S=3/2 ions on a kagom\'{e} lattice. In a sample with $\approx$ 76%
+occupancy of the chromium sites the ordered moment is 1.1(3)$\mu_B$ per
+chromium ion which is only one third of the N\'{e}el value $g\mu_BS=3\mu_B$.
+The magnetic unit cell equals the chemical unit cell, a situation which is
+favored by inter-plane interactions. Gapless quantum spin-fluctuations
+($\Delta/k_B <0.25$K) with a bandwidth of 60K >> $T_N$ = 1.6K are the dominant
+contribution to the spin correlation function, $S(Q,\omega)$ in the ordered
+phase.",9705014v1
+1997-09-08,Spin Density Functional Based Search for Half-Metallic Antiferromagnets,"We present results based on local spin density calculations of a
+computational search for half-metallic (HM) antiferromagnetic (AFM) materials
+within the class of double perovskite structure oxides LaM'M''O3 that
+incorporate open shell 3d (or 4d) transition metal ions M', M''. The pairs
+M'M'' = MnCo, CrFe, CrRu, CrNi, MnV, and VCu are studied. La2VMnO6 is the most
+promising candidate, with the HM AFM phase more stable by 0.17 eV/cell than the
+ferromagnetic phase. La2VCuO6 is another promising possibility, but due to
+S=1/2 ions quantum fluctuations my play an important role in determining the
+ground state magnetic and electronic structure. This study indicates that HM
+AFM materials should not be prohibitively difficult to find.",9709100v1
+1998-05-10,Assisted Tunneling in Ferromagnetic Junctions and Half-Metallic Oxides,"Different mechanisms of spin-dependent tunneling are analyzed with respect to
+their role in tunnel magnetoresistance (TMR). Microscopic calculation within a
+realistic model shows that direct tunneling in iron group systems leads to
+about a 30% change in resistance, which is close but lower than experimentally
+observed values. The larger observed values of the tunnel magnetoresistance
+(TMR) might be a result of tunneling involving surface polarized states. It is
+found that tunneling via resonant defect states in the barrier radically
+decreases the TMR by order of magnitude. One-magnon emission is shown to reduce
+the TMR, whereas phonons increase the effect. The inclusion of both magnons and
+phonons reasonably explains an unusual bias dependence of the TMR. The model
+presented here is applied qualitatively to half-metallics with 100% spin
+polarization, where one-magnon processes are suppressed and the change in
+resistance in the absence of spin-mixing on impurities may be arbitrarily
+large. Even in the case of imperfect magnetic configurations, the resistance
+change can be a few 1000 percent. Examples of half-metallic systems are
+CrO2/TiO2 and CrO2/RuO2.",9805114v1
+1998-07-16,On the Theory of Metal-Insulator Transitions in Gated Semiconductors,"It is shown that recent experiments indicating a metal-insulator transition
+in 2D electron systems can be interpreted in terms of a simple model, in which
+the resistivity is controlled by scattering at charged hole traps located in
+the oxide layer. The gate voltage changes the number of charged traps which
+results in a sharp change in the resistivity. The observed exponential
+temperature dependence of the resistivity in the metallic phase of the
+transition follows from the temperature dependence of the trap occupation
+number. The model naturally describes the experimentally observed scaling
+properties of the transition and effects of magnetic and electric fields.",9807245v1
+1999-03-15,Metal-insulator transition in CMR materials,"We report on resistivity measurements in La$_{0.67}$Ca$_{0.33}$MnO$_{3}$ and
+Nd$_{0.7}$Sr$_{0.3}$MnO$_{3}$ thin films in order to elucidate the underlying
+mechanism for the CMR behavior. The experimental results are analyzed in terms
+of quantum phase transition ideas to study the nature of the metal-insulator
+transition in manganese oxides. Resistivity curves as functions of
+magnetization for various temperatures show the absence of scaling behavior
+expected in a continuous quantum phase transition, which leads us to conclude
+that the observed metal-insulator transition is most likely a finite
+temperature crossover phenomenon.",9903238v2
+1999-08-12,The Essential Interactions in Oxides and Spectral Weight Transfer in Doped Manganites,"We calculate the value of the Fr\""ohlich electron-phonon interaction in
+manganites, cuprates, and some other charge-transfer insulators and show that
+this interaction is much stronger than any relevant magnetic interaction. A
+polaron shift due to the Fr\""ohlich interaction, which is about 1 eV, suggests
+that carriers in those systems are small (bi)polarons at all temperatures and
+doping levels, in agreement with the oxygen isotope effect and other data. An
+opposite conclusion, recently suggested in the literature, is shown to be
+incorrect. The frequency and temperature dependence of the optical conductivity
+of ferromagnetic manganites is explained within the framework of the bipolaron
+theory.",9908183v3
+1999-10-16,Charge and orbital order in half-doped manganites,"An explanation is given for the charge order, orbital order and insulating
+state observed in half-doped manganese oxides, such as
+Nd$_{1/2}$Sr$_{1/2}$MnO$_{3}$. The competition between the kinetic energy of
+the electrons and the magnetic exchange energy drives the formation of
+effectively one-dimensional ferromagnetic zig-zag chains. Due to a topological
+phase factor in the hopping, the chains are intrinsically insulating and
+orbital-ordered. Most surprisingly, the strong Coulomb interaction between
+electrons on the same Mn-ion leads to the experimentally observed charge
+ordering. For doping less than 1/2 the system is unstable towards phase
+separation into a ferromagnetic metallic and charge-ordered insulating phase.",9910253v1
+2000-03-14,"Magnetoresistance in ordered and disordered double perovskite oxide, Sr$_2$FeMoO$_6$","We have prepared crystallographically ordered and disorder specimens of the
+double perovskite, Sr$_2$FeMoO$_6$ and investigated their magnetoresistance
+behaviour. The extent of ordering between the Fe and Mo sites in the two
+samples is determined by Rietveld analysis of powder x-ray diffraction patterns
+and reconfirmed by M\""{o}ssbauer studies. While the ordered sample exhibits the
+sharp low-field response, followed by moderate changes in the magnetoresistance
+at higher fields, the disordered sample is characterised by the absence of the
+spectacular low-field response. We argue that the low field response depends
+crucially on the half-metallic ferromagnetism, while the high-field response
+follows from the overall magnetic nature of the sample, even in absence of the
+half-metallic state.",0003237v1
+2001-03-02,Sharp resonant multiplet in femto-second optical pair-breaking spectroscopy of YBa2Cu3O7-delta,"Femto-second optical pair breaking spectroscopy is performed on optimally
+doped YBa2Cu3O7-delta near 1.5eV. Dramatic photon energy dependence with a
+sharp triplet fine structure is seen for the first time. The peak separations
+are attributable to the reported phonon and magnetic excitations in the system.
+The power dependence is non-linear with differing exponents for the three
+contributions. These results imply the presence of insulating antiferromagnetic
+domains in the superconducting state of YBCO over sub-picosecond time scale,
+and thereby favor an electronic phase separation picture.",0103046v1
+2001-06-21,207Pb and 17O NMR Study of the Electron Density Distribution in Metal Phase of BaPb_{1-x}Bi_xO_3,"The 17O and 207Pb NMR spectra were measured in ceramic samples in the
+metallic phase of BaPb_{1-x}Bi_{x}O_3 oxides (0<x< 0.33). The inhomogeneous
+magnetic broadening which appears due to a distribution of the Knight shifts
+was analyzed in detail. It is shown that Bi atoms, which are randomly
+incorporated in BaPbO_3 parent compound give rise to an increased conduction
+electron spin density within an area which is delimited by its two first cation
+shells. According to NMR data the percolative overlap of these areas occurs in
+superconducting compositions and it is accompanied by a sharp growth of the
+average Knight shift <Ks>. The decrease of <17Ks> with temperature revealed for
+x=0.33 evidences for an opening of the energy gap near E_F near the
+metal-semiconductor transition (x=0.35).",0106431v1
+2002-01-22,Anisotropic Exchange in LiCuVO$_4$ probed by ESR,"We investigated the paramagnetic resonance in single crystals of LiCuVO$_4$
+with special attention to the angular variation of the absorption spectrum. To
+explain the large resonance linewidth of the order of 1 kOe, we analyzed the
+anisotropic exchange interaction in the chains of edge-sharing CuO$_6$
+octahedra, taking into account the ring-exchange geometry of the
+nearest-neighbor coupling via two symmetric rectangular Cu-O bonds. The
+exchange parameters, which can be estimated from theoretical considerations,
+nicely agree with the parameters obtained from the angular dependence of the
+linewidth. The anisotropy of this magnetic ring exchange is found to be much
+larger than it is usually expected from conventional estimations which neglect
+the bonding geometry. Hence, the data yield the evidence that in copper oxides
+with edge-sharing structures the role of the orbital degrees of freedom is
+strongly enhanced. These findings establish LiCuVO$_4$ as one-dimensional
+compound at high temperatures.
+  PACS: 76.30.-v, 76.30.Fc, 75.30.Et",0201403v1
+2002-04-24,Superconducting Transition and Vortex Pinning in Nb Films Patterned with Nano-scale Hole-arrays,"Nb films containing extended arrays of holes with 45-nm diameter and 100-nm
+spacing have been fabricated using anodized aluminum oxide (AAO) as substrate.
+Pronounced matching effects in the magnetization and Little-Parks oscillations
+of the superconducting critical temperature have been observed in fields up to
+9 kOe. Flux pinning in the patterned samples is enhanced by two orders of
+magnitude as compared to unpatterned reference samples in applied fields
+exceeding 5 kOe. Matching effects are a dominant contribution to vortex pinning
+at temperatures as low as 4.2 K due to the extremely small spacing of the
+holes.",0204535v1
+2002-07-05,On the two-dimensional metallic state in silicon-on-insulator structures,"It is shown that the electronic conduction in silicon-on-insulator (SOI)
+layers exhibits a metallic regime which is very similar to that in
+high-mobility Si-metal oxide semiconductor structures (MOS). The peak in the
+electron mobility versus density, the strong drop in resistivity and the
+critical concentration for the metal-insulator transition are all consistent.
+On the basis of our SOI data for the temperature and in-plane magnetic field
+dependence of the resistivity, we discuss several models for the metallic state
+in two dimensions. We find that the observed behavior can be well described by
+the theory on the interaction corrections in the ballistic regime. For the
+investigated regime, the temperature dependent screening of scattering
+potentials gives also a good description of the data.",0207170v1
+2002-07-31,Transport anisotropy in biaxially strained La(2/3)Ca(1/3)MnO(3) thin films,"Due to the complex interplay of magnetic, structural, electronic, and orbital
+degrees of freedom, biaxial strain is known to play an essential role in the
+doped manganites. For coherently strained La(2/3)Ca(1/3)MnO(3) thin films grown
+on SrTiO(3) substrates, we measured the magnetotransport properties both
+parallel and perpendicular to the substrate and found an anomaly of the
+electrical transport properties. Whereas metallic behavior is found within the
+plane of biaxial strain, for transport perpendicular to this plane an
+insulating behavior and non-linear current-voltage characteristics (IVCs) are
+observed. The most natural explanation of this anisotropy is a strain induced
+transition from an orbitally disordered ferromagnetic state to an orbitally
+ordered state associated with antiferromagnetic stacking of ferromagnetic
+manganese oxide planes.",0207730v1
+2002-08-06,Ground state of the three-band Hubbard model,"The ground state of the two-dimensional three-band Hubbard model in oxide
+superconductors is investigated by using the variational Monte Carlo method.
+The Gutzwiller-projected BCS and spin- density wave (SDW) functions are
+employed in the search for a possible ground state with respect to dependences
+on electron density. Antiferromagnetic correlations are considerably enhanced
+near half-filling. It is shown that the d-wave state may exist away from
+half-filling for both the hole and electron doping cases. The overall structure
+of the phase diagram obtained by the calculations qualitatively agrees with
+experimental indications. The superconducting condensation energy is in
+reasonable agreement with the experimental value obtained from specific heat
+and critical magnetic field measurements for optimally doped samples. The
+inhomogeneous SDW state is also examined near 1/8-hole doping.",0208105v1
+2002-09-05,Ground state properties of ferromagnetic metal/conjugated polymer interfaces,"We theoretically investigate the ground state properties of ferromagnetic
+metal/conjugated polymer interfaces. The work is partially motivated by recent
+experiments in which injection of spin polarized electrons from ferromagnetic
+contacts into thin films of conjugated polymers was reported. We use a
+one-dimensional nondegenerate Su-Schrieffer-Heeger (SSH) Hamiltonian to
+describe the conjugated polymer and one-dimensional tight-binding models to
+describe the ferromagnetic metal. We consider both a model for a conventional
+ferromagnetic metal, in which there are no explicit structural degrees of
+freedom, and a model for a half-metallic ferromagnetic colossal
+magnetoresistance (CMR) oxide which has explicit structural degrees of freedom.
+The Fermi energy of the magnetic metallic contact is adjusted to control the
+degree of electron transfer into the polymer. We investigate electron charge
+and spin transfer from the ferromagnetic metal to the organic polymer, and
+structural relaxation near the interface. Bipolarons are the lowest energy
+charge state in the bulk polymer for the nondegenerate SSH model Hamiltonian.
+As a result electrons (or holes) transferred into the bulk of the polymer form
+spinless bipolarons. However, there can be spin density in the polymer
+localized near the interface.",0209145v1
+2002-11-04,Unveiling New Magnetic Phases of Undoped and Doped Manganites,"Novel ground-state spin structures in undoped and lightly-doped manganites
+are here investigated based on the orbital-degenerate double-exchange model, by
+using mean-field and numerical techniques. In undoped manganites, a new
+antiferromagnetic (AFM) state, called the E-type phase, is found adjacent in
+parameter space to the A-type AFM phase. Its structure is in agreement with
+recent experimental results. This insulating E-AFM state is also competing with
+a ferromagnetic metallic phase as well, suggesting that large magneto-resistant
+effects could exist even in undoped Mn oxides. For doped layered manganites,
+the phase diagram includes another new AFM phase of the ${\rm C_x
+E_{1-x}}$-type. Experimental signatures of the new phases are discussed.",0211049v2
+2002-11-11,V-V Bond-Length Fluctuations in Vox,"We report a significantly stronger suppression of the phonon contribution to
+the thermal conductivity in VOx than can be accounted for by disorder of the 16
+% atomic vacancies present in VO. Since the transition from localized to
+itinerant electronic behavior is first-order and has been shown to be
+characterized by bond-length fluctuations in several transition-metal oxides
+with the perovskite structure, we propose that cooperative V-V bond-length
+fluctuations play a role in VO similar to the M-O bond-length fluctuations in
+the perovskites. This model is able to account for the strong suppression of
+the thermal conductivity, the existence of a pseudogap confirmed by
+thermoelectric power, an anomalously large Debye-Waller factor, the temperature
+dependence of the magnetic susceptibility, and the inability to order atomic
+vacancies in VO.",0211208v1
+2002-12-02,Anisotropic Optic Conductivities due to Spin and Orbital Orderings in LaVO3 and YVO3: First-Principles Studies,"The anisotropy of low energy (0$\sim$5eV) optical excitations in strongly
+correlated transition-metal oxides is closely related to the spin and orbital
+orderings. The recent successes of LDA+$U$ method in describing the magnetic
+and electronic structures enable us to calculate the optical conductivity from
+first-principles. The LaVO$_3$ and YVO$_3$, both of which have $3d^2$
+configuration and have various spin and orbital ordered phases at low
+temperature, show distinct anisotropy in the optical spectra. The effects of
+spin and orbital ordering on the anisotropy are studied in detail based on our
+first-principles calculations. The experimental spectra of both compounds at
+low temperature phases can be qualitatively explained with our calculations,
+while the studies for the intermediate temperature phase of YVO$_3$ suggest the
+substantial persistence of the low temperature phase at elevated temperature.",0212024v1
+2003-05-28,59Co-NQR study on superconducting NaxCoO2.yH2O,"Layered Co oxide NaxCoO2.yH2O with a superconducting transition temperature
+Tc =4.5 K has been studied by 59Co NQR. The nuclear spin relaxation rate 1/59T1
+is nearly proportional to temperature T in the normal state. In the
+superconducting state, it exhibits the coherence peak and decreases with
+decreasing T below ~0.8Tc. Detailed comparison of the 1/T1T values and the
+magnetic susceptibilities between NaxCoO2.yH2O and NaxCoO2 implies that the
+metallic state of the former system is closer to a ferromagnetic phase than
+that of the latter. These experimental results impose a restriction on the
+mechanism of the superconductivity.",0305649v2
+2003-06-11,59Co-NMR Knight Shift of the Superconducting NaxCoO2.yH2O,"Layered Co oxide NaxCoO2.yH2O with the superconducting transition temperature
+Tc =4.5 K has been studied by 59Co-NMR. The Knight shift K estimated from the
+observed spectra for powder sample exhibits almost temperature(T)-independent
+behavior above Tc and decreases with decreasing T below Tc. This result and the
+existence of the coherence peak in the spin-lattice-relaxation-rate versus T
+curve reported by the present authors indicate, naively speaking, that the
+singlet order parameter with s-wave symmetry is realized in NaxCoO2.yH2O.
+Differences of the observed behaviors between the spectra of the non-aligned
+sample and the one aligned in epoxy adhesive by applying the external magnetic
+field are discussed.",0306264v2
+2003-06-25,Superlight bipolarons and a checkerboard d-wave condensate in cuprates,"The seminal work by Bardeen, Cooper and Schrieffer taken further by
+Eliashberg to the intermediate coupling solved the problem of conventional
+superconductors about half a century ago. The Froehlich and Jahn-Teller
+electron-phonon interactions were identified as an essential piece of physics
+in all novel superconductors. The BCS theory provides a qualitatively correct
+description of some of them like magnesium diborade and doped fullerenes (if
+the polaron formation is taken into account). However, cuprates remain a
+problem. Here I show that the bipolaron extension of the BCS theory to the
+strong-coupling regime could be a solution. Low-energy physics in this regime
+is that of small 'superlight' bipolarons, which are real-space mobile bosonic
+pairs dressed by phonons. The symmetry and space modulations of the order
+parameter are explained in the framework of the bipolaron theory. A d-wave
+Bose-Einstein condensate of bipolarons reveals itself as a checkerboard
+modulation of the hole density and of the gap below Tc.",0306649v2
+2003-07-09,Frequency Dependence of Magnetoelectric Interactions in Layered Structures of Ferromagnetic Alloys and Piezoelectric Oxides,"Magnetoelectric (ME) interactions in layered structures of magnetostrictive
+and piezoelectric phases are mediated by mechanical deformation. Here we
+discuss the frequency dependence of ME coupling in bilayers and trilayers of
+Permendur, a ferromagnetic alloy, and lead zirconate titanate. Data on ME
+voltage coefficient versus frequency profiles reveal a giant ME coupling at
+electromechanical resonance. The maximum voltage coefficient of 90 V/cm Oe is
+three orders of magnitude higher than low-frequency values. The ME interactions
+for transverse fields is an order of magnitude stronger than for longitudinal
+fields. These results are in agreement with theory. The resonance ME effect,
+therefore, is a novel tool for enhancing the magnetic-to-electric field
+conversion efficiency in the composites.",0307208v1
+2003-07-25,Superconductivity-Related Insulating Behavior,"We present the results of an experimental study of superconducting,
+disordered, thin-films of amorphous Indium Oxide. These films can be driven
+from the superconducting phase to a reentrant insulating state by the
+application of a perpendicular magnetic field ($B$). We find that the high-$B$
+insulator exhibits activated transport with a characteristic temperature,
+$T_I$. $T_I$ has a maximum value ($T_{I}^p$) that is close to the
+superconducting transition temperature ($T_c$) at $B$ = 0, suggesting a
+possible relation between the conduction mechanisms in the superconducting and
+insulating phases. $T_{I}^p$ and $T_c$ display opposite dependences on the
+disorder strength.",0307648v2
+2003-10-10,The Silicon Inversion Layer With A Ferromagnetic Gate: A Novel Spin Source,"Novel spin transport behavior is theoretically shown to result from replacing
+the usual metal (or poly-silicon) gate in a silicon field-effect transistor
+with a ferromagnet, separated from the semiconductor by an ultra-thin oxide.
+The spin-dependent interplay between the drift current (due to a source-drain
+bias) and the diffusion current (due to carrier leakage into the ferromagnetic
+gate) results in a rich variety of spin dependence in the current that flows
+through such a device. We examine two cases of particular interest: (1)
+creating a 100% spin-polarized electrical current and (2) creating a pure spin
+current without a net electrical current. A spin-valve consisting of two
+sequential ferromagnetic gates is shown to exhibit magnetoresistance dependent
+upon the relative orientations of the magnetization of the two ferromagnets.
+The magnetoresistance ratio grows to arbitrarily large values in the regime of
+low source-drain bias, and is limited only by the spin-flip time in the
+channel.",0310259v1
+2003-10-15,Continuous Charge Modulated Diagonal Phase in Manganites,"We present a novel ground state that explain the continuous modulated charge
+diagonal order recently observed in manganese oxides, at hole densities $x$
+larger than one half. In this diagonal phase the charge is modulated with a
+predominant Fourier component inversely proportional to $1-x$. Magnetically
+this state consist of antiferromagnetic coupled zig-zag chains. For a wide
+range of relevant physical parameters as electron-phonon coupling,
+antiferromagnetic interaction between Mn ions and on-site Coulomb repulsion,
+the diagonal phase is the ground state of the system. The diagonal phase is
+favored by the modulation of the hopping amplitude along the zig-zag chains,
+and it is stabilized with respect to the one dimensional straight chain by the
+electron phonon coupling. For realistic estimation of the physical parameters,
+the diagonal modulation of the electron density is only a small fraction of the
+average charge, a modulation much smaller than the obtained by distributing
+Mn$^{+3}$ and Mn$^{+4}$ ions. We discuss also the spin and orbital structure
+properties of this new diagonal phase.",0310333v1
+2003-11-23,"A brief review of recent advances on the Mott transition: unconventional transport, spectral weight transfers, and critical behaviour","Strongly correlated metals close to the Mott transition display unusual
+transport regimes, together with large spectral weight transfers in optics and
+photoemission. We briefly review the theoretical understanding of these
+effects, based on the dynamical mean-field theory, and emphasize the key role
+played by the two energy scales associated with quasiparticle coherence scale
+and with the Mott gap. Recent experimental results on two-dimensional organic
+compounds and transition metal oxides are considered in this perspective. The
+liquid-gas critical behaviour at the Mott critical endpoint is also discussed.
+Transport calculations using the numerical renormalization group are presented.",0311520v2
+2004-01-14,Substrate surface engineering for tailoring properties of functional ceramic thin films,"Using oxide substrates for functional ceramic thin film deposition beyond
+their usual application as chemical inert, lattice-matched support for the
+films represents a novel concept in ceramic thin film research. The substrates
+are applied as a functional element in order to controllably modify the atom
+arrangement and the growth mode of ceramic prototype materials such as cuprate
+superconductors and colossal magnetoresistance manganites. One example is the
+use of epitaxial strain to adjust the relative positions of cations and anions
+in the film and thus modify their physical properties. The other makes use of
+vicinal cut SrTiO3 which enables the fabrication of regular nanoscale step and
+terrace structures. In YBa2Cu3O7-x thin films grown on vicinal cut SrTiO3
+single crystals a regular array of antiphase boundaries is generated causing an
+anisotropic enhancement of flux-line pinning. In the case of La-Ca-Mn-O thin
+films grown on vicinal cut substrates it could be demonstrated that magnetic
+in-plane anisotropy is achieved.",0401233v1
+2004-02-09,"Oxygen and Cation Ordered Perovskite, Ba2Y2Mn4O11","A three-step route has been developed for the synthesis of a new
+oxygen-ordered double perovskite, BaYMn2O5.5 or Ba2Y2Mn4O11. (i) The A-site
+cation ordered perovskite, BaYMn2O5+d, is first synthesized at d ~ 0 by an
+oxygen-getter-controlled low-O2-pressure encapsulation technique utilizing FeO
+as the getter for excess oxygen. (ii) The as-synthesized, oxygen-deficient
+BaYMn2O5.0 phase is then readily oxygenated to the d ~ 1 level by means of
+1-atm-O2 annealing at low temperatures. (iii) By annealing this
+fully-oxygenated BaYMn2O6.0 in flowing N2 gas at moderate temperatures the new
+intermediate-oxygen-content oxide, BaYMn2O5.5 or Ba2Y2Mn4O11, is finally
+obtained. From thermogravimetric observation it is seen that the final oxygen
+depletion from d ~ 1.0 to 0.5 occurs in a single sharp step about 600 C,
+implying that the oxygen stoichiometry of BaYMn2O5+d is not continuously
+tunable within 0.5 < d < 1.0. For BaYMn2O5.5 synchrotron x-ray diffraction
+analysis reveals an orthorhombic crystal lattice and a long-range ordering of
+the excess oxygen atoms in the YO0.5 layer. The magnetic behavior of BaYMn2O5.5
+(with a ferromagnetic transition at ~ 133 K) is found different from those
+previously reported for the known phases, BaYMn2O5.0 and BaYMn2O6.0.",0402230v1
+2004-03-18,Experimental evidence for a collective insulating state in two-dimensional superconductors,"We present the results of an experimental study of the current-voltage
+characteristics in strong magnetic field ($B$) of disordered, superconducting,
+thin-films of amorphous Indium-Oxide. As the $B$ strength is increased
+superconductivity degrades, until a critical field ($B_c$) where the system is
+forced into an insulating state. We show that the differential conductance
+measured in the insulating phase vanishes abruptly below a well-defined
+temperature, resulting in a clear threshold for conduction. Our results
+indicate that a new collective state emerges in two-dimensional superconductors
+at high $B$.",0403480v2
+2004-03-30,Persistence of an Energy Scale in Over-Doped High-Tc Superconductors,"Citing the disappearance of a sharp peak in the electron self-energy,
+extracted from optics and angle-resolved photoemission spectroscopy (ARPES)
+experiments in deeply over-doped copper-oxide superconductors with Tc of
+55-60K, Hwang, Timusk et al. argue that sharp modes, be they phononic or
+magnetic in origin, are not important for superconductivity in the cuprates. If
+true, this would have been an important progress. We show, however, their
+conclusions are unfounded because of the insensitivity of the optics experiment
+in studying strongly anisotropic material like the cuprates, and a
+misrepresentation of existing ARPES data. In an added note, we refute the claim
+by Valla, Timusk et. al. that the doping level of the data presented in the
+first part of this comment is lower than reported.",0403743v2
+2004-04-10,A novel heavy-fermion state in CaCu_3Ru_4O12,"We have measured susceptibility, specific heat, resistivity, and thermopower
+of CaCu$_3$Ti$_{4-x}$Ru$_x$O$_{12}$ and CaCu$_{3-y}$Mn$_y$Ru$_4$O$_{12}$, and
+have found that CaCu$_3$Ru$_4$O$_{12}$ can be regarded as a heavy-fermion oxide
+in d-electron systems. The Kondo temperature is near 200 K, and the
+susceptibility (1.4$\times10^{-3}$ emu/Cu mol) and the electron specific heat
+coefficient (28 mJ/Cu molK$^2$) are moderately enhanced. The resistivity is
+proportional to $T^2$ at low temperatures, and satisfies the Kadowaki-Woods
+relation. The heavy-fermion state comes from the interaction between the
+localized moment of Cu 3d and the conduction electron of Ru 4d. An
+insulator-metal transition occurs between $x=1.5$ and 4 in
+CaCu$_3$Ti$_{4-x}$Ru$_x$O$_{12}$, which can be regarded as a transition from
+magnetic insulator to heavy-fermion metal.",0404247v1
+2004-04-23,Percolation and Colossal Magnetoresistance in Eu-based Hexaborides,"Upon substituting Ca for Eu in the local-moment ferromagnet EuB$_6$, the
+Curie temperature $T_C$ decreases substantially with increasing dilution of the
+magnetic sublattice and is completely suppressed for $x$ $\leq$ 0.3. The Ca
+substitution leads to significant changes of the electronic properties across
+the Eu$_x$Ca$_{1-x}$B$_6$ series. Electron microscopy data for $x$ $\approx$
+0.27 indicate a phase separation into Eu- and Ca-rich clusters of 5 to 10 nm
+diameter, leading to percolation-type phenomena in the electrical transport
+properties. The related critical concentration $x_p$ is approximately 0.3. For
+$x$ $\approx$ 0.27, we observe colossal negative magnetoresistance effects at
+low temperatures, similar in magnitude as those reported for manganese oxides.",0404570v1
+2004-06-09,Exchange coupling in Eu monochalcogenides from first principles,"Using a density functional method with explicit account for strong Coulomb
+repulsion within the 4f shell, we calculate effective exchange parameters and
+the corresponding ordering temperatures of the (ferro)magnetic insulating Eu
+monochalcogenides (EuX; X=O,S,Se,Te) at ambient and elevated pressure
+conditions. Our results provide quantitative account of the many-fold increase
+of the Curie temperatures with applied pressure and reproduce well the
+enhancement of the tendency toward ferromagnetic ordering across the series
+from telluride to oxide, including the crossover from antiferromagnetic to
+ferromagnetic ordering under pressure in EuTe and EuSe. The first and second
+neighbor effective exchange are shown to follow different functional
+dependencies. Finally, model calculations indicate a significant contribution
+of virtual processes involving the unoccupied f states to the effective
+exchange.",0406229v1
+2004-06-17,Re-entrant Behavior and Gigantic Response in Disordered Spin-Peierls System,"Effects of disorder and external field on the competing spin-Peierls and
+antiferromagnetic states are studied theoretically in terms of the numerical
+transfer matrix method applied to a quasi one-dimensional spin 1/2 Heisenberg
+model coupled to the lattice degree of freedom. We show that, at temperatures
+above the impurity-induced antiferromagnetic phase, inhomogeneous spin-Peierls
+lattice distortions remain to exist showing a re-entrant behavior. This feature
+can be drastically altered by very weak perturbations, e.g., the staggered
+magnetic field or the change in interchain exchange coupling $J_\perp$, leading
+to a huge response, which is analogous to the colossal magnetoresistance
+phenomenon in perovskite manganese oxides.",0406386v1
+2004-06-21,An Origin of CMR: Competing Phases and Disorder-Induced Insulator-to-Metal Transition in Manganites,"We theoretically explore the mechanism of the colossal magnetoresistance in
+manganese oxides by explicitly taking into account the phase competition
+between the double-exchange ferromagnetism and the charge-ordered insulator. We
+find that quenched disorder causes a drastic change of the multicritical phase
+diagram by destroying the charge-ordered state selectively. As a result, there
+appears a nontrivial phenomenon of the disorder-induced insulator-to-metal
+transition in the multicritical regime. On the contrary, the disorder induces a
+highly-insulating state above the transition temperature where charge-ordering
+fluctuations are much enhanced. The contrasting effects provide an
+understanding of the mechanism of the colossal magnetoresistance. The obtained
+scenario is discussed in comparison with other theoretical proposals such as
+the polaron theory, the Anderson localization, the multicritical-fluctuation
+scenario, and the percolation scenario.",0406463v1
+2004-06-22,Stability and electronic structure of the complex K$_2$PtCl$_6$ structure-type hydrides,"The stability and bonding of the ternary complex K$_2$PtCl$_6$ structure
+hydrides is discussed using first principles density functional calculations.
+The cohesion is dominated by ionic contributions, but ligand field effects are
+important, and are responsible for the 18-electron rule. Similarities to oxides
+are discussed in terms of the electronic structure. However, phonon
+calculations for Sr$_2$RuH$_6$ also show differences, particularly in the
+polarizability of the RuH$_6$ octahedra. Nevertheless, the yet to be made
+compounds Pb$_2$RuH$_6$ and Be$_2$FeH$_6$ are possible ferroelectrics. The
+electronic structure and magnetic properties of the decomposition product,
+FeBe$_2$ are reported. Implications of the results for H storage are discussed.",0406506v1
+2004-07-22,Strongly correlated crystal-field approach to Mott insulator LaCoO3,"Our success in description of recent electron-spin-resonance results on Mott
+insulator LaCoO3, Phys. Rev. B 67 (2003) 172401, lies in taking into account
+strong electron correlations among d electrons and the relativistic spin-orbit
+coupling. In the developed by us Quantum Atomistic Solid State Theory (QUASST)
+we assume that the atomic-like integrity of the 3d^6 system is preserved in the
+Co^3+ ion in LaCoO3 and that intra-atomic correlations are much stronger than
+crystal field interactions. We conclude that in LaCoO3 there is no intermediate
+spin state as came out from band-structure calculations. The excited states
+originate from the high-spin 5T2g term, being 12 meV above the ground 1A1
+state. We are convinced that many-electron CEF approach with strong
+correlations and the atomic-scale orbital magnetism is physically adequate
+approach to 3d oxides.
+  Keywords: Mott insulator, crystal field, spin-orbit coupling, LaCoO3",0407580v2
+2004-09-08,Non-linear Temperature Dependence of Resistivity in Single Crystalline Ag$_5$Pb$_2$O$_6$,"We measured electrical resistivity, specific heat and magnetic susceptibility
+of single crystals of highly conductive oxide Ag_5Pb_2O_6, which has a layered
+structure containing a Kagome lattice. Both the out-of-plane and in-plane
+resistivity show T^2 dependence in an unusually wide range of temperatures up
+to room temperature. This behavior cannot be accounted for either by electron
+correlation or by electron-phonon scattering with high frequency optic phonons.
+In addition, a phase transition with a large diamagnetic signal was found in
+the ac susceptibility, which strongly suggests the existence of a
+superconducting phase below 48 mK.",0409184v2
+2004-09-21,Spin Frustration and Orbital Order in Vanadium Spinels,"We present the results of our theoretical study on the effects of geometrical
+frustration and the interplay between spin and orbital degrees of freedom in
+vanadium spinel oxides $A$V$_2$O$_4$ ($A$ = Zn, Mg or Cd). Introducing an
+effective spin-orbital-lattice coupled model in the strong correlation limit
+and performing Monte Carlo simulation for the model, we propose a reduced spin
+Hamiltonian in the orbital ordered phase to capture the stabilization mechanism
+of the antiferromagnetic order. Orbital order drastically reduces spin
+frustration by introducing spatial anisotropy in the spin exchange
+interactions, and the reduced spin model can be regarded as weakly-coupled
+one-dimensional antiferromagnetic chains. The critical exponent estimated by
+finite-size scaling analysis shows that the magnetic transition belongs to the
+three-dimensional Heisenberg universality class. Frustration remaining in the
+mean-field level is reduced by thermal fluctuations to stabilize a collinear
+ordering.",0409526v1
+2004-10-20,Variation of Specific Heat with x and y in NaxCoO2-yH2O/D2O,"We report specific heat measurements down to 0.4 K on the layered oxide
+Na$_x$CoO$_2\cdot\it{y}$H$_2$O/D$_2$O with 0 $\le$ $\it{x}$ $\le$ 0.74 and
+$\it{y}$ = 0 and 1.4. For the nonhydrated system ($\it{y}$ = 0), the electronic
+specific heat coefficient $\gamma_N$ and the Debye temperature $\Theta_D$ vary
+nonmonotonically with $\it{x}$, both displaying minima when $\it{x}$ is close
+to 0.5. This indicates a systematic change of the electronic and vibrational
+structures with Na content. For both hydrated and deuterated systems ($\it{x}$
+= 0.35 and $\it{y}$ = 1.4), the specific heat reveals a sharp peak with
+$\Delta$C$_p \sim$ 45.5 mJ/mol-K at T$_c^{mid} \sim$ 4.7 K and an anomaly at
+T$_x \sim$ 0.8 K. While the origin of the later is unknown, the former
+corresponds to the superconducting transition. Interestingly, the electronic
+specific heat, after subtracting lattice and Schottky contributions, exhibits
+roughly T$^2$ behavior between 0.2T$_c$ and T$_c$. This can be explained by
+assuming an unconventional superconducting symmetry with line nodes. The
+results obtained under applied magnetic field further support this scenario.",0410517v1
+2005-01-31,Colossal magnetoresistance and quenched disorder in manganese oxides,"We give an overview on several recent topics of colossal magnetoresistive
+manganites in both experiments and theories, focusing on the effect of quenched
+disorder. The disorder is intrinsically involved since the compounds are solid
+solutions, and its importance has been pointed out in several experiments of
+transport and magnetic properties. Recent progress in the experimental control
+of the strength of disorder is also reviewed. Theoretically, the effect of the
+disorder has been explored within the framework of the double-exchange
+mechanism. Several efforts to understand the phase diagram and the electronic
+properties are reviewed. We also briefly discuss a recent topic on the effect
+of disorder on competing phases and the origin of colossal magnetoresistance.",0501738v1
+2005-02-04,Critical point and the nature of the pseudogap of single-layered copper-oxide Bi$_{2}$Sr$_{2-x}$La$_{x}$CuO$_{6+δ}$ superconductors,"We apply strong magnetic fields of H=28.5 \sim 43 T to suppress
+superconductivity (SC) in the cuprates Bi_{2}Sr_{2-x}La_xCuO_{6+\delta}
+(x=0.65, 0.40, 0.25, 0.15 and 0), and investigate the low temperature (T)
+normal state by ^{63}Cu nuclear spin-lattice relaxation rate (1/T_1)
+measurements. We find that the pseudogap (PG) phase persists deep inside the
+overdoped region but terminates at x \sim 0.05 that corresponds to the hole
+doping concentration of approximately 0.21. Beyond this critical point, the
+normal state is a Fermi liquid characterized by the T_1T=const relation. A
+comparison of the superconducting state with the H-induced normal state in the
+x=0.40 (T_c = 32 K) sample indicates that there remains substantial part of the
+Fermi surface even in the fully-developed PG state, which suggests that the PG
+and SC are coexisting matters.",0502117v1
+2005-03-10,Ferromagnetic and triplet-pairing instabilities controlled by the trigonal distortion of the CoO_6 octahedra in Na_xCoO_2*yH_2O,"In the recently discovered Co-oxide superconductor Na_xCoO_2*yH_2O, the
+edge-shared CoO6 octahedra are trigonally contracted along the c-axis in the
+CoO2-plane. We study how this CoO6 distortion affects the magnetic properties
+and superconductivity in this compound by analyzing the multiorbital Hubbard
+model using the fluctuation-exchange approximation. It is shown that through
+generating the trigonal crystal field, the distortion pushes the Co e'g bands
+up and consequently gives rise to the hole-pocket Fermi surfaces, which have
+been predicted in the band calculations. As the distortion increases, the hole
+pockets are enlarged and the ferromagnetic fluctuation as well as the pairing
+instability increases, which is in good agreement with recent NQR results.",0503233v2
+2005-05-10,Novel organic-inorganic layered oxide with spin ladder structure,"Structural analysis of a layered manganese tungstate diaminoalkane hybrid
+series suggests that this compound forms a spin-5/2 spin-ladder structure. We
+use X-ray diffraction, electron microscopy and x-ray absorption spectroscopy
+results to infer the structure. DC magnetization of the manganese compound and
+a possible copper analogue appear to show that the manganese system behaves
+like 1-dimensional antiferromagnetic Heisenberg chains (i.e. $J_{\parallel} \gg
+J_{\perp})$ while the copper system is fitted well by a $S = {1/2}$ spin ladder
+model, giving the parameters $g = 1.920 \pm 0.008$, $J_{\parallel}/k_B = -0.3
+\pm 1.4$K; $J_{\perp}/k_B = 213.6 \pm 1.1$K. The ability to tune adjacent
+inorganic layers of the hybrid materials by altering the length of the organic
+`spacer' molecules gives enormous promise for the use of these materials,
+especially when doped, to provide a greater understanding of spin ladder
+systems.",0505224v1
+2005-05-19,"Fish-tail Effect and Irreversibility Field of (Cu,C)Ba$_{2}$Ca$_{3}$Cu$_{4}$O$_{x}$-(LiF)$_{y}$ superconductor","Addition of (LiF)$_{y<0.15}$, and of proper amount of (AgO)$_{z=0.45-0.8}$ as
+oxidizing agent, to (Cu,C)Ba$_{2}$Ca$_{3}$Cu$_{4}$O$_{10+d}$ superconductor is
+useful to control and shift the doping characteristics (hole density and
+distribution, and level of disorder) into the region where the irreversible
+properties, i.e. fish-tail effect (FTE) and irreversibility field H$_{irr}$,
+are improved. Among notable effects are the development of the second
+magnetization peak with a higher amplitude J$_{c}$, max and the enhancement of
+H$_{irr}$ at high temperatures, above a certain value T* which depends on both
+y$_{LiF}$ and z$_{AgO}$. The best results are obtained for the sample with
+y$_{LiF}$=0.1 and z$_{AgO}$=0.73. This sample preserves its single phase
+Cu,C-1234 composition. The influence on the FTE and H$_{irr}$ of the interplay
+between doping characteristics, controlled by LiF and AgO content, is
+discussed.",0505494v1
+2005-06-05,On the unusual behavior of nitride compounds,"This report presents consistent insight into the mechanism behind the unusual
+behavior of nitride compounds from the perspective of tetrahedron bond
+formation and its consequence on valence density of states. An extension of the
+recent bond-band-barrier (BBB) correlation mechanism for oxidation [Sun CQ,
+Prog Mater Sci 2003;48:521-685] to the electronic process of nitridation has
+led to the essentiality of sp-orbital hybridization for a nitrogen atom upon
+interacting with atoms in solid phase of arbitrary less-electronegative
+element. In the process of nitridation, a nitrogen atom forms a
+quasi-tetrahedron with surrounding host atoms through bonding and nonbonding
+interaction associated with production of electronic holes and antibonding
+dipoles, which add corresponding density of states to the valence band of the
+host. It is suggested that the valance alteration of the system takes the
+responsibility for the blue shift in photoluminescence, lowered work function
+for cold cathode field emission, corrosion and wear resistant, high elasticity,
+and magnetic modulation as well.",0506109v1
+2005-07-15,2D Kagome Ordering in the 3D Frustrated Spinel Li2Mn2O4,"muSR experiments on the geometrically frustrated spinel oxide, Li2Mn2O4, show
+the development of spin correlations over a range of length scales with
+decreasing temperature. Increased relaxation below 150 K is consistent with the
+onset of spin correlations. Below 50 K, spin order on a length scale, which is
+long range for the muSR probe, appears abruptly in temperature, consistent with
+prior neutron diffraction results. The oscillations in the zero field asymmetry
+are analyzed using a three frequency model. By locating the muon site this is
+shown to be consistent with the unexpected 2D q = root 3 x root 3 structure on
+the Kagome planes proposed originally from neutron data. Longitudinal field
+data demonstrate that some spin dynamics persist even at 2 K. Thus, a very
+complex magnetic ground state, featuring the co-existence of long length scale
+2D ordering and significant spin dynamics, is proposed. This is unusual
+considering the 3D topology of the Mn3+ spins in this material.",0507355v1
+2005-07-15,Metamagnetic quantum criticality in Sr3Ru2O7 studied by thermal expansion,"We report low-temperature thermal expansion measurements on the bilayer
+ruthenate Sr$_3$Ru$_2$O$_7$ as a function of magnetic field applied
+perpendicular to the Ruthenium-oxide planes. The field-dependence of the c-axis
+expansion coefficient indicates the accumulation of entropy close to 8 Tesla,
+related to an underlying quantum critical point. The latter is masked by two
+first-order metamagnetic transitions which bound a regime of enhanced entropy.
+Outside this region the singular thermal expansion behavior is compatible with
+the predictions of the itinerant theory for a two-dimensional metamagnetic
+quantum critical end point.",0507359v3
+2005-07-30,Metamagnetic Quantum Criticality Revealed by 17O-NMR in the Itinerant Metamagnet Sr3Ru2O7,"We have investigated the spin dynamics in the bilayered perovskite Sr3Ru2O7
+as a function of magnetic field and temperature using 17O-NMR. This system sits
+close to a metamagnetic quantum critical point (MMQCP) for the field
+perpendicular to the ruthenium oxide planes. We confirm Fermi-liquid behavior
+at low temperatures except for a narrow field region close to the MMQCP. The
+nuclear spin-lattice relaxation rate divided by temperature 1/T1T is enhanced
+on approaching the metamagnetic critical field of 7.9 T and at the critical
+field 1/T1T continues to increase and does not show Fermi- liquid behavior down
+to 0.3 K. The temperature dependence of T1T in this region suggests the
+critical temperature Theta to be 0 K, which is a strong evidence that the spin
+dynamics possesses a quantum critical character. Comparison between uniform
+susceptibility and 1/T1T reveals that antiferromagnetic fluctuations instead of
+two-dimensional ferromagnetic fluctuations dominate the spin fluctuation
+spectrum at the critical field, which is unexpected for itinerant
+metamagnetism.",0508012v1
+2005-08-08,Novel phase diagram of superconductor NaxCoO2-yH2O in a 75 % relative humidity,"We succeeded in synthesizing the powder samples of bilayer-hydrate sodium
+cobalt oxide superconductors NaxCoO2-yH2O with Tc = 0 ~ 4.6 K by systematically
+changing the keeping duration in a 75 % relative humidity atmosphere after
+intercalation of water molecules. From the magnetic measurements, we found that
+the one-day duration sample does not show any superconductivity down to 1.8 K,
+and that the samples kept for 2 ~ 7 days show superconductivity, in which Tc
+increases up to 4.6 K with increasing the duration. Tc and the superconducting
+volume fraction are almost invariant between 7 days and 1month duration. The
+59Co NQR spectra indicate a systematic change in the local charge distribution
+on the CoO2 plane with change in duration.",0508196v1
+2005-09-21,Tunneling magnetoresistance in devices based on epitaxial NiMnSb with uniaxial anisotropy,"We demonstrate tunnel magnetoresistance (TMR) junctions based on a tri layer
+system consisting of an epitaxial NiMnSb, aluminum oxide and CoFe tri layer.
+The junctions show a tunnelling magnetoresistance of Delta R/R of 8.7% at room
+temperature which increases to 14.7% at 4.2K. The layers show clear separate
+switching and a small ferromagnetic coupling. A uniaxial in plane anisotropy in
+the NiMnSb layer leads to different switching characteristics depending on the
+direction in which the magnetic field is applied, an effect which can be used
+for sensor applications.",0509538v1
+2005-10-03,Buffer-Enhanced Electrical-Pulse-Induced-Resistive Memory Effect in Thin Film Perovskites,"A multilayer perovskite thin film resistive memory device has been developed
+comprised of: a Pr0.7Ca0.3MnO3 (PCMO) perovskite oxide epitaxial layer on a
+YBCO bottom thin film electrode; a thin yttria stabilized zirconia (YSZ) buffer
+layer grown on the PCMO layer, and a gold thin film top electrode. The
+multi-layer thin film lattice structure has been characterized by XRD and TEM
+analyses showing a high quality heterostructure. I-AFM analysis indicated nano
+granular conductivity distributed uniformly throughout the PCMO film surface.
+With the addition of the YSZ buffer layer, the pulse voltage needed to switch
+the device is significantly reduced and the resistance-switching ratio is
+increased compared to a non-buffered resistance memory device, which is very
+important for the device fabrication. The magnetic field effect on the
+multilayer structure resistance at various temperatures shows CMR behavior for
+both high and low resistance states implying a bulk material component to the
+switch behavior.",0510060v1
+2005-10-15,Quasiparticle Self-Consistent GW Theory,"In past decades the scientific community has been looking for a reliable
+first-principles method to predict the electronic structure of solids with high
+accuracy. Here we present an approach which we call the quasiparticle
+self-consistent GW approximation (QpscGW). It is based on a kind of
+self-consistent perturbation theory, where the self-consistency is constructed
+to minimize the perturbation. We apply it to selections from different classes
+of materials, including alkali metals, semiconductors, wide band gap
+insulators, transition metals, transition metal oxides, magnetic insulators,
+and rare earth compounds. Apart some mild exceptions, the properties are very
+well described, particularly in weakly correlated cases. Self-consistency
+dramatically improves agreement with experiment, and is sometimes essential.
+Discrepancies with experiment are systematic, and can be explained in terms of
+approximations made.",0510408v2
+2005-10-19,Oxygen Isotope Effect on the Spin State Transition in (Pr$_{0.7}$Sm$_{0.3}$)$_{0.7}$Ca$_{0.3}$CoO${_3}$,"Oxygen isotope substitution is performed in the perovskite cobalt oxide
+(Pr$_{0.7}$Sm$_{0.3}$)$_{0.7}$Ca$_{0.3}$CoO${_3}$ which shows a sharp spin
+state transition from the intermediate spin (IS) state to the low spin (LS)
+state at a certain temperature. The transition temperature of the spin state
+up-shifts with the substitution of $^{16}O$ by $^{18}$O from the resistivity
+and magnetic susceptibility measurements. The up-shift value is 6.8 K and an
+oxygen isotope exponent ($\alpha_S$) is about -0.8. The large oxygen isotope
+effect indicates strong electron-phonon coupling in this material. The
+substitution of $^{16}$O by $^{18}$O leads to a decrease in the frequency of
+phonon and an increase in the effective mass of electron ($m$$^\ast$), so that
+the bandwidth W is decreased and the energy difference between the different
+spin states is increased. This is the reason why the $T_s$ is shifted to high
+temperature with oxygen isotopic exchange.",0510499v1
+2005-10-31,Time-Resolved Spin Torque Switching and Enhanced Damping in Py/Cu/Py Spin-Valve Nanopillars,"We report time-resolved measurements of current-induced reversal of a free
+magnetic layer in Py/Cu/Py elliptical nanopillars at temperatures T = 4.2 K to
+160 K. Comparison of the data to Landau-Lifshitz-Gilbert macrospin simulations
+of the free layer switching yields numerical values for the spin torque and the
+Gilbert damping parameters as functions of T. The damping is strongly
+T-dependent, which we attribute to the antiferromagnetic pinning behavior of a
+thin permalloy oxide layer around the perimeter of the free layer. This
+adventitious antiferromagnetic pinning layer can have a major impact on spin
+torque phenomena.",0510798v2
+2006-02-16,Manifestation of the Exchange Enhancement of the Valley Splitting in the Quantum Hall Effect Regime,"We report a new ""dip"" effect in the Hall resistance, R_{xy}, of a Si
+metal-oxide-semiconductor field-effect transistor in the quantum Hall effect
+regime. With increasing magnetic field, the Hall resistance moves from the
+plateau at Landau filling factor \nu=6 directly to the plateau at \nu=4,
+skipping the plateau at \nu=5. However, when the filling factor approaches
+\nu=5, the Hall resistance sharply ""dives"" to the value 1/5(h/e^2)
+characteristic of the \nu=5 plateau, and then returns to 1/4(h/e^2). This is
+interpreted as a manifestation of the oscillating exchange enhancement of the
+valley splitting when the Fermi level is in the middle between two adjacent
+valley-split Landau bands with the asymmetric position of the extended states.",0602376v1
+2006-03-31,Evidences of a consolute critical point in the Phase Separation regime of La(5/8-y)Pr(y)Ca(3/8)MnO(3) (y = 0.4) single crystals,"We report on DC and pulsed electric field sensitivity of the resistance of
+mixed valent Mn oxide based La(5/8-y)Pr(y)Ca(3/8)MnO(3) (y = 0.4) single
+crystals as a function of temperature. The low temperature regime of the
+resistivity is highly current and voltage dependent. An irreversible transition
+from high (HR) to a low resistivity (LR) is obtained upon the increase of the
+electric field up to a temperature dependent critical value (V_c). The
+current-voltage characteristics in the LR regime as well as the lack of a
+variation in the magnetization response when V_c is reached indicate the
+formation of a non-single connected filamentary conducting path. The
+temperature dependence of V_c indicates the existence of a consolute point
+where the conducting and insulating phases produce a critical behavior as a
+consequence of their separation.",0603850v1
+2006-05-19,23Na NMR study of non-superconducting double-layer hydrate NaxCoO2.yH2O,"We report 23Na NMR studies of the polycrystalline samples of double-layer
+hydrated cobalt oxides NaxCoO2.yH2O (x ~ 0.35 and y ~ 1.3) with the
+superconducting transition temperatures Tc < 1.8K and ~4.5K, and the dehydrated
+NaxCoO2 (x ~ 0.35). The hyperfine field and the electric field gradient at the
+Na sites in the non-hydrated Na0.7CoO2 and the dehydrated Na0.35CoO2 are found
+to be significantly reduced by the hydration, which indicates a strong
+shielding effect of the intercalated water molecules on the Na sites. The
+temperature dependence of 23 Na nuclear spin-lattice relaxation rate 1/23T1 of
+the non-superconducting double-layer hydrate NaxCoO2.yH2O is found to be
+similar to that of the non-hydrated Na0.7CoO2, whose spin dynamics is
+understood by A-type (intra-layer ferromagnetic and inter-layer
+antiferromagnetic) spin fluctuations. The superconducting phase is located
+close to the quantum critical point with the A-type magnetic instability.",0605487v2
+2006-06-02,Effects of spin-phonon interaction on the properties of in high-T$_C$ superconductors,"The mechanism of spin-phonon coupling in high-T$_C$ copper oxides is explored
+from band calculations on La$_{(2-x)}$Sr$_x$CuO$_4$ and HgBa$_2$CuO$_4$
+systems. The LMTO band calculations, based on the local density approximation,
+are made for cells containing frozen phonon displacements and/or spin waves
+within the CuO plane. The virtual crystal approximation is used for studies of
+hole doped systems. The main result is that phonons are favorable for spin
+waves and vice-versa, and that pseudogaps appear naturally in the band
+structures of striped materials with strong SPC. The qualitative results are
+compatible with many observations showing that the properties of high-T$_C$
+superconductors depend both on lattice interactions and magnetic fluctuations.
+The band results are used to model various properties, mainly of the normal
+state, such as isotope effects, pseudogaps, Fermi surface broadening,
+T-dependence of the pseudogap, phonon softening and some aspects of
+superconductivity. The possibility of perpendicular SPC is investigated, partly
+by the use of a nearly free electron model.",0606066v1
+2006-07-06,Strongly correlated electrons,"We review theoretical concepts and models for materials with strongly
+correlated d- or f electrons. We discuss low-energy effective models and the
+renormalized band method for Ce-based Kondo lattice systems. They are applied
+to the analysis of associated magnetic and superconducting instabilities. In
+addititon quantum phase transitions are investigated. Special emphasis is given
+to the partial localisation of 5f electrons in U compounds and its consequences
+for unconventional superconductivity. Wigner crystallisation in the homogeneous
+electron gas and its generalisation to 4f pnictide and 3d oxide materials is
+covered extensively. We analyse simultaneous charge order and lattice
+instabilities in geometrically frustrated V-oxide spinels. Using a spinless
+fermion model we also discuss the emergence of fractional charges in the
+frustrated pyrochlore or checkerboard lattice. Finally we focus on the
+signature of strong electronic correlations in high-energy excitations.",0607165v1
+2006-07-31,Optical study of MgTi$_2$O$_4$: Evidence for an orbital-Peierls state,"Dimension reduction due to the orbital ordering has recently been proposed to
+explain the exotic charge, magnetic and structural transitions in some
+three-dimensional (3D) transitional metal oxides. We present optical
+measurement on a spinel compound MgTi$_2$O$_4$ which undergoes a sharp
+metal-insulator transition at 240 K, and show that the spectral change across
+the transition can be well understood from the proposed picture of 1D Peierls
+transition driven by the ordering of $d_{yz}$ and $d_{zx}$ orbitals. We further
+elaborate that the orbital-driven instability picture applies also very well to
+the optical data of another spinel CuIr$_2$S$_4$ reported earlier.",0607813v2
+2006-10-05,Anomalous Superconducting Proximity Effect in Hybrid Oxide Heterostructures with Antiferromagnetic Layer,"We report an investigation of current transport in Nb/Au/CaSrCuO/YBaCuO
+heterostructures including an antiferromagnetic interlayer (CaSrCuO). Epitaxial
+thin films of YBaCuO and CaSrCuO were grown by laser ablation on NdGaO
+substrates; the thicknesses of CaSrCuO films were 20 and 50 nm, and x=0.15 or
+0.5. Our experimental results show that the superconducting current transport
+is increased in the Nb/Au/CaSrCuO/YBaCuO heterostructures in comparison with
+the ones observed in previously studied Nb/Au/YBaCuO heterostructures. It was
+found that the critical current of the structure is very sensitive to the
+absolute value and direction of the external magnetic field.",0610140v1
+2006-10-27,NMR Observation of Rattling Phonons in the Pyrochlore Superconductor KOs2O6,"We report nuclear magnetic resonance studies on the beta-pyrochlore oxide
+superconductor KOs2O6. The nuclear relaxation at the K sites is entirely caused
+by fluctuations of electric field gradient, which we ascribe to highly
+anharmonic low frequency oscillation (rattling) of K ions. A phenomenological
+analysis shows a crossover from overdamped to underdamped behavior of the
+rattling phonons with decreasing temperature and its sudden sharpening below
+the superconducting transition temperature Tc. Absence of the Hebel-Slichter
+peak in the relaxation rate at the O sites below Tc also indicates strong
+electron-phonon coupling.",0610760v2
+2006-11-25,Long-range ferromagnetic correlations between Anderson impurities in a semiconductor host,"We study the two-impurity Anderson model for a semiconductor host using the
+quantum Monte Carlo technique. We find that the impurity spins exhibit
+ferromagnetic correlations with a range which can be much more enhanced than in
+a half-filled metallic band. In particular, the range is longest when the Fermi
+level is located above the top of the valence band and decreases as the
+impurity bound state becomes occupied. Comparisons with the photoemission and
+optical absorption experiments suggest that this model captures the basic
+electronic structure of Ga_{1-x}Mn_xAs, the prototypical dilute magnetic
+semiconductor (DMS). These numerical results might also be useful for
+synthesizing DMS or dilute-oxide ferromagnets with higher Curie temperatures.",0611641v1
+2006-12-29,Intrinsic Nanoscale Inhomogeneities in Transition Metal Oxides,"Neutron elastic, inelastic and high energy x-ray scattering techniques are
+used to explore the nature of the polaron order and dynamics in La0.7Ca0.3MnO3.
+Static polaron correlations develop within a narrow temperature regime as the
+Curie temperature is approached from low temperatures, with a nanoscale
+correlation length that is only weakly temperature dependent. The static nature
+of these short-range polaron correlations indicates the presence of a
+glass-like state, similar to the observations for the bilayer manganite in the
+metallic-ferromagnetic doping region. In addition to this elastic component,
+inelastic scattering measurements reveal dynamic correlations with a comparable
+correlation length, and with an energy distribution that is quasielastic. The
+elastic component disappears at a higher temperature T*, above which the
+correlations are purely dynamic. The overall behavior bears a remarkable
+resemblance to the magnetic fluctuation spectrum recently observed in
+underdoped cuprates.",0701001v1
+2007-01-19,"Reversible Ferromagnetic Switching in Zno:(Co,Mn) Powders","We report here on the magnetic properties of ZnO:Mn and ZnO:Co doped
+nanoparticles. We have found that the ferromagnetism of ZnO:Mn can be switched
+on and off by consecutive low-temperature annealings in O2 and N2 respectively,
+while the opposite phenomenology was observed for ZnO:Co. These results suggest
+that different defects (presumably n-type for ZnO:Co and p-type for ZnO:Mn) are
+required to induce a ferromagnetic coupling in each case. We will argue that
+ferromagnetism is likely to be restricted to a very thin, nanometric layer, at
+the grain surface. These findings reveal and give insight into the dramatic
+relevance of surface effects for the occurrence of ferromagnetism in ZnO doped
+oxides.",0701473v1
+2007-02-12,Wannier functions and exchange integrals: The example of LiCu$_{2}$O$_{2}$,"Starting from a single band Hubbard model in the Wannier function basis, we
+revisit the problem of the ligand contribution to exchange and derive explicit
+formulae for the exchange integrals in metal oxide compounds in terms of atomic
+parameters that can be calculated with constrained LDA and LDA+U. The analysis
+is applied to the investigation of the isotropic exchange interactions of
+LiCu$_{2}$O$_{2}$, a compound where the Cu-O-Cu angle of the dominant exchange
+path is close to 90$^{\circ}$. Our results show that the magnetic moments are
+localized in Wannier orbitals which have strong contribution from oxygen atomic
+orbitals, leading to exchange integrals that considerably differ from the
+estimates based on kinetic exchange only. Using LSDA+U approach, we also
+perform a direct {\it ab-initio} determination of the exchange integrals
+LiCu$_{2}$O$_{2}$. The results agree well with those obtained from the Wannier
+function approach, a clear indication that this modelization captures the
+essential physics of exchange. A comparison with experimental results is also
+included, with the conclusion that a very precise determination of the Wannier
+function is crucial to reach quantitative estimates.",0702276v1
+2007-03-21,DFT investigation of 3d transition metal NMR shielding tensors in diamagnetic systems using the gauge-including projector augmented-wave method,"We present a density functional theory based method for calculating NMR
+shielding tensors for 3d transition metal nuclei using periodic boundary
+conditions. Calculations employ the gauge-including projector augmented-wave
+pseudopotentials method. The effects of ultrasoft pseudopotential and induced
+approximations on the second-order magnetic response are intensively examined.
+The reliability and the strength of the approach for 49Ti and 51V nuclei is
+shown by comparison with traditional quantum chemical methods, using benchmarks
+of finite organometallic systems. Application to infinite systems is validated
+through comparison to experimental data for the 51V nucleus in various vanadium
+oxide based compounds. The successful agreement obtained for isotropic chemical
+shifts contrasts with full estimation of the shielding tensor eigenvalues,
+revealing the limitation of pure exchange-correlation functionals compared to
+their exact-exchange corrected analogues.",0703553v2
+2000-10-03,Modeling of an Inductive Adder Kicker Pulser for Darht-II,"An all solid-state kicker pulser for a high current induction accelerator
+(the Dual-Axis Radiographic Hydrodynamic Test facility DARHT-2) has been
+designed and fabricated. This kicker pulser uses multiple solid state
+modulators stacked in an inductive-adder configuration. Each modulator is
+comprised of multiple metal-oxide-semiconductor field-effect transistors
+(MOSFETs) which quickly switch the energy storage capacitors across a magnetic
+induction core. Metglas is used as the core material to minimize loss. Voltage
+from each modulator is inductively added by a voltage summing stalk and
+delivered to a 50 ohm output cable. A lumped element circuit model of the
+inductive adder has been developed to optimize the performance of the pulser.
+Results for several stalk geometries will be compared with experimental data.",0010007v2
+2005-03-21,Photonic band structure of ZnO photonic crystal slab laser,"We recently reported on the first realization of ultraviolet photonic crystal
+laser based on zinc oxide [Appl. Phys. Lett. {\bf 85}, 3657 (2004)]. Here we
+present the details of structural design and its optimization. We develop a
+computational super-cell technique, that allows a straightforward calculation
+of the photonic band structure of ZnO photonic crystal slab on sapphire
+substrate. We find that despite of small index contrast between the substrate
+and the photonic layer, the low order eigenmodes have predominantly
+transverse-electric (TE) or transverse-magnetic (TM) polarization. Because
+emission from ZnO thin film shows strong TE preference, we are able to limit
+our consideration to TE bands, spectrum of which can possess a complete
+photonic band gap with an appropriate choice of structure parameters. We
+demonstrate that the geometry of the system may be optimized so that a sizable
+band gap is achieved.",0503170v1
+2007-06-30,Quantum Oscillations in the Underdoped Cuprate YBa2Cu4O8,"We report the observation of quantum oscillations in the underdoped cuprate
+superconductor YBa2Cu4O8 using a tunnel-diode oscillator technique in pulsed
+magnetic fields up to 85T. There is a clear signal, periodic in inverse field,
+with frequency 660+/-15T and possible evidence for the presence of two
+components of slightly different frequency. The quasiparticle mass is
+m*=3.0+/-0.3m_e. In conjunction with the results of Doiron-Leyraud et al. for
+YBa2Cu3O6.5, the present measurements suggest that Fermi surface pockets are a
+general feature of underdoped copper oxide planes and provide information about
+the doping dependence of the Fermi surface.",0707.0057v2
+2007-08-29,Evidence of orbital reconstruction at interfaces in La0.67Sr0.33MnO3 films,"Electronic properties of transition metal oxides at interfaces are influenced
+by strain, electric polarization and oxygen diffusion. Linear dichroism (LD)
+x-ray absorption, diffraction, transport and magnetization on thin
+La0.7Sr0.3MnO3 films, allow identification of a peculiar universal interface
+effect. We report the LD signature of preferential 3d-eg(3z2-r2) occupation at
+the interface, suppressing the double exchange mechanism. This surface orbital
+reconstruction is opposite of that favored by residual strain and independent
+of dipolar fields, chemical nature of the substrate and capping.",0708.3973v2
+2007-09-04,Spin-Filtering Multiferroic-Semiconductor Heterojunctions,"We report on the structural and electronic properties of the interface
+between the multiferoic oxide YMnO$_3$ and wide band-gap semiconductor GaN
+studied with the Hubbard-corrected local spin density approximation (LSDA+U) to
+density-functional theory (DFT). We find that the band offsets at the interface
+between antiferromagnetically ordered YMnO$_3$ and GaN are different for
+spin-up and spin-down states. This behavior is due to the spin splitting of the
+valence band induced by the interface. The energy barrier depends on the
+relative orientation of the electric polarization with respect to the
+polarization direction of the GaN substrate suggesting an opportunity to create
+magnetic tunnel junctions in this materials system.",0709.0318v1
+2007-10-03,Scaling analysis of normal state properties of high-temperature superconductors,"We propose a model-independent scaling method to study the physical
+properties of high-temperature superconductors in the normal state. We have
+analyze the experimental data of the c-axis resistivity, the in-plane
+resistivity, the Hall coefficient, the magnetic susceptibility, the
+spin-lattice relaxation rate, and the thermoelectric power using this method.
+It is shown that all these physical quantities exhibit good scaling behaviors,
+controlled purely by the pseudogap energy scale in the normal state. The doping
+dependence of the pseudogap obtained from this scaling analysis agrees with the
+experimental results of angle-resolved photoemission and other measurements. It
+sheds light on the understanding of the basic electronic structure of high-Tc
+oxides.",0710.0693v3
+2007-10-11,Exploiting B Site Disorder for Phase Control in the Manganites,"Disorder on the active d element site is usually very disruptive for
+conduction and long range order in perovskite transition metal oxides. However,
+in the background of phase competition such `B site' dopants also act to
+promote one ordered phase at the expense of another. This occurs either through
+valence change of the transition metal or via creation of `defects' in the
+parent magnetic state. We provide a framework for understanding the complex
+variety of phenomena observed in B site doped manganites and identify the key
+parameters that control the physics. Using a spatially resolved analysis of B
+ions in various manganite phases we explain the existing data and predict new
+situations where highly polarisable phase separated states can be created.",0710.2278v3
+2007-10-17,Superfluid density of superconductor-ferromagnet bilayers,"We report the first measurements of the effective superfluid density n_S(T)
+\propto \lambda^{-2}(T) of Superconductor-Ferromagnet (SC/FM) bilayers, where
+\lambda is the effective magnetic field penetration depth. Thin Nb/Ni bilayers
+were sputtered in ultrahigh vacuum in quick succession onto oxidized Si
+substrates. Nb layers are 102 A thick for all samples, while Ni thicknesses
+vary from 0 to 100 A. T_C determined from \lambda^{-2}(T) decreases rapidly as
+Ni thickness d_Ni increases from zero to 15 A, then it has a shallow minimum at
+d_Ni \approx 25 A. \lambda^{-2}(0) behaves similarly, but has a minimum several
+times deeper. In fact, \lambda^{-2}(0) continues to increase with increasing Ni
+thickness long after T_C has stopped changing. We argue that this indicates a
+substantial superfluid density inside the ferromagnetic Ni films.",0710.3376v1
+2007-11-01,Relationship between ferroelectricity and Dzyaloshinskii-Moriya interaction in multiferroics and the effect of bond-bending,"We studied the microscopic mechanism of multiferroics, in particular with the
+""spin current"" model (Hosho Katsura, Naoto Nagaosa and Aleander V. Balatsky,
+Phys. Rev. Lett. 95, 057205 (2005)). Starting from a system with helical spin
+configuration, we solved for the forms of the electron wave functions and
+analyzed their characteristics. The relation between ferroelectricity and
+Dzyaloshinskii-Moriya interaction (I. Dzyaloshinskii, J. Phys. Chem. Solids 4,
+241 (1958) and T. Moriya, Phys. Rev. 120, 91 (1960)) is clearly established.
+There is also a simple relation between the electric polarization and the wave
+vector of magnetic orders. Finally, we show that the bond-bending exists in
+transition metal oxides can enhance ferroelectricity.",0711.0100v2
+2007-11-29,Systematic changes of the electronic structure of the diluted ferromagnetic oxide Li-doped Ni$_{1-x}$Fe$_x$O with hole doping,"The electronic structure of Li-doped Ni$_{1-x}$Fe$_x$O has been investigated
+using photoemission spectroscopy (PES) and x-ray absorption spectroscopy (XAS).
+The Ni $2p$ core-level PES and XAS spectra were not changed by Li doping. In
+contrast, the Fe$^{3+}$ intensity increased with Li doping relative to the
+Fe$^{2+}$ intensity. However, the increase of Fe$^{3+}$ is only $\sim 5%$ of
+the doped Li content, suggesting that most of the doped holes enter the O $2p$
+and/or the charge-transferred configuration Ni $3d^8\underline{L}$. The Fe 3d
+partial density of states and the host valence-band emission near valence-band
+maximum increased with Li content, consistent with the increase of electrical
+conductivity. Based on these findings, percolation of bound magnetic polarons
+is proposed as an origin of the ferromagnetic behavior.",0711.4658v1
+2007-12-04,Pressure dependence of the superconducting transition and electron correlations in Na_xCoO_2 \cdot 1.3H_2O,"We report T_c and ^{59}Co nuclear quadrupole resonance (NQR) measurements on
+the cobalt oxide superconductor Na_{x}CoO_{2}\cdot 1.3H_{2}O (T_c=4.8 K) under
+hydrostatic pressure (P) up to 2.36 GPa. T_c decreases with increasing pressure
+at an average rate of -0.49\pm0.09 K/GPa. At low pressures P\leq0.49 GPa, the
+decrease of T_c is accompanied by a weakening of the spin correlations at a
+finite wave vector and a reduction of the density of states (DOS) at the Fermi
+level. At high pressures above 1.93 GPa, however, the decrease of T_c is mainly
+due to a reduction of the DOS. These results indicate that the
+electronic/magnetic state of Co is primarily responsible for the
+superconductivity. The spin-lattice relaxation rate 1/T_1 at P=0.49 GPa shows a
+T^3 variation below T_c down to T\sim 0.12T_c, which provides compelling
+evidence for the presence of line nodes in the superconducting gap function.",0712.0419v1
+2008-01-28,Hybridization between the conduction band and 3d orbitals in the oxide-based diluted magnetic semiconductor In$_{2-x}$V$_x$O$_3$,"The electronic structure of In$_{2-x}$V$_x$O$_3$ ($x=0.08$) has been
+investigated using photoemission spectroscopy (PES) and x-ray absorption
+spectroscopy (XAS). The V $2p$ core-level PES and XAS spectra revealed
+trivalent electronic state of the V ion, consistent with the substitution of
+the V ion for the In site. The V 3d partial density of states obtained by the
+resonant PES technique showed a sharp peak above the O $2p$ band. While the O
+$1s$ XAS spectrum of In$_{2-x}$V$_x$O$_3$ was similar to that of In$_2$O$_3$,
+there were differences in the In $3p$ and 3d XAS spectra between V-doped and
+pure In$_2$O$_3$. The observations give clear evidence for hybridization
+between the In conduction band and the V 3d orbitals in In$_{2-x}$V$_x$O$_3$.",0801.4244v1
+2008-02-08,"Superconducting Transition in the $β$-Pyrochlore AOs$_2$O$_6$ (A=Cs, Rb, K) under Pressure","Pressure dependence of superconducting transition temperature $T_{\rm c}$ has
+been determined through the DC magnetic measurements under pressure up to
+$P$=10 GPa for $\beta$-pyrochlore oxides AOs$_2$O$_6$ with A=Cs ($T_{\rm
+c}$=3.3 K), Rb (6.3 K) and K (9.6 K). Both for A=Rb and Cs, $T_{\rm c}$
+increases with increasing $P$ and shows a saturation at $T_{\rm cm}$$\sim$8.8
+K, which is considered as the upper limit of $T_{\rm c}$ inherent in
+AOs$_2$O$_6$. In contrast, the $T_{\rm c}-P$ curve for KOs$_2$O$_6$ shows a
+sharp maximum of $\sim$10 K at $P$$\sim$0.5 GPa, and $T_{\rm c}$ is higher than
+$T_{\rm cm}$ for 0$\leq$$P$$\leq$1.5GPa, suggesting the enhanced
+superconductivity due to the rattling of K ions.",0802.1179v1
+2008-03-04,Magneto-Dielectric phenomena in charge and spin frustrated system of layered iron oxide,"Dielectric and magnetic phenomena in spin and charge frustrated system RFe2O4
+(R is a rare-earth metal ion) are studied. An electronic model for charge, spin
+and orbital degrees in a pair of triangular-lattice planes is derived. We
+analyze this model by utilizing the mean-field approximation and the
+Monte-Carlo simulation in a finite size cluster. A three fold-type charge
+ordered structure with charge imbalance between the planes is stabilized in
+finite temperatures. This polar charge order is reinforced by spin ordering of
+Fe ions. This novel magneto-dielectric phenomenon is caused by spin frustration
+and charge-spin coupling in the exchange interaction. We show cross-correlation
+effect in magnetic- and electric-field responses. Oxygen deficiency effect as
+an impurity effect in a frustrated charge-spin coupled system is also examined.",0803.0394v1
+2008-03-06,Tight-Binding Theory of Manganese and Iron Oxides,"The electronic structure is found to be understandable in terms of free-atom
+term values and universal interorbital coupling parameters, since
+self-consistent tight-binding calculations indicate that Coulomb shifts of the
+d-state energies are small. Special-point averages over the bands are seen to
+be equivalent to treatment of local octahedral clusters. The cohesive energy
+per manganese for MnO, Mn2O3, and MnO2, in which manganese exists in valence
+states Mn2+, Mn3+, and Mn4+, is very nearly the same and dominated by the
+transfer of manganese s electrons to oxygen p states. There are small
+corrections, one eV per Mn in all cases, from couplings of minority-spin
+states. Transferring one majority-spin electron from an upper cluster state to
+a nonbonding oxygen state adds 1.67 eV to the cohesion for Mn2O3, and two
+transfers adds twice that for MnO2 . The electronic and magnetic properties are
+consistent with this description and appear to be understandable in terms of
+the same parameters.",0803.0994v1
+2008-03-20,Novel Jeff = 1/2 Mott State Induced by Relativistic Spin-Orbit Coupling in Sr2IrO4,"We investigated electronic structure of 5d transition-metal oxide Sr2IrO4
+using angle-resolved photoemission, optical conductivity, and x-ray absorption
+measurements and first-principles band calculations. The system was found to be
+well described by novel effective total angular momentum Jeff states, in which
+relativistic spin-orbit (SO) coupling is fully taken into account under a large
+crystal field. Despite of delocalized Ir 5d states, the Jeff-states form so
+narrow bands that even a small correlation energy leads to the Jeff = 1/2 Mott
+ground state with unique electronic and magnetic behaviors, suggesting a new
+class of the Jeff quantum spin driven correlated-electron phenomena.",0803.2927v1
+2008-03-27,Hydroxyl vacancies in single-walled aluminosilicate and aluminogermanate nanotubes,"We report the first theoretical study of hydroxyl vacancies in
+aluminosilicate and aluminogermanate single-walled metal-oxide nanotubes. The
+defects are modeled on both sides of the tube walls and lead to occupied and
+empty states in the band gap which are highly localized both in energy and in
+real space. We find different magnetization states depending on both the
+chemical composition and the specific side with respect to the tube cavity. The
+defect-induced perturbations to the pristine electronic structure are related
+to the electrostatic polarization across the tube walls and the ensuing change
+in Br{\o}nsted acid-base reactivity. Finally, the capacity to counterbalance
+local charge accumulations, a characteristic feature of these systems, is
+discussed in view of their potential application as insulating coatings for
+one-dimensional conducting nanodevices.",0803.3915v1
+2008-08-15,Magneto-Optical Trap for Polar Molecules,"We propose a method for laser cooling and trapping a substantial class of
+polar molecules, and in particular titanium (II) oxide (TiO). This method uses
+pulsed electric fields to nonadiabatically remix the ground-state magnetic
+sublevels of the molecule, allowing us to build a magneto-optical trap (MOT)
+based on a quasi-cycling $J'=J""-1$ transition. Monte-Carlo simulations of this
+electrostatically remixed MOT (ER-MOT) demonstrate the feasibility of cooling
+TiO to a temperature of 10 $\mathrm{\mu}K$ and trapping it with a
+radiation-pumping-limited lifetime on the order of 80 ms.",0808.2171v2
+2008-09-16,Interaction Effects in Conductivity of a Two-Valley Electron System in High-Mobility Si Inversion Layers,"We have measured the conductivity of high-mobility (001) Si
+metal-oxide-semiconductor field effect transistors (MOSFETs) over wide ranges
+of electron densities n=(1.8-15)x10^11cm^2, temperatures T=30mK-4.2K, and
+in-plane magnetic fields B=0-5T. The experimental data have been analyzed using
+the theory of interaction effects in the conductivity of disordered 2D systems.
+The parameters essential for comparison with the theory, such as the
+intervalley scattering time and valley splitting, have been measured or
+evaluated in independent experiments. The observed behavior of the
+conductivity, including its quasi-linear increase with decreasing T down to
+~0.4K and its downturn at lower temperatures, is in agreement with the theory.
+The values of the Fermi- liquid parameter obtained from the comparison agree
+with the corresponding values extracted from the analysis of Shubnikov-de Haas
+oscillations based on the theory of magnetooscillations in interacting 2D
+systems.",0809.2750v1
+2008-10-29,Tetragonal CuO: A new end member of the 3d transition metal monoxides,"Monoclinic CuO is anomalous both structurally as well as electronically in
+the 3$d$ transition metal oxide series. All the others have the cubic rock salt
+structure. Here we report the synthesis and electronic property determination
+of a tetragonal (elongated rock salt) form of CuO created using an epitaxial
+thin film deposition approach. In situ photoelectron spectroscopy suggests an
+enhanced charge transfer gap $\Delta$ with the overall bonding more ionic. As
+an end member of the 3d transition monoxides, its magnetic properties should be
+that of a high $T_N$ antiferromagnet.",0810.5231v1
+2008-11-12,Slow Dynamics in Hard Condensed Matter: A Case Study of the Phase Separating System NdNiO$_3$,"We report the time dependent response of electrical resistivity in the
+non-magnetic perovskite oxide NdNiO$_3$ in its phase separated state and
+provide a physical explanation of the observations. We also model the system
+and do an accurate Monte Carlo simulation of the observed behavior. While
+cooling a phase separation takes place in this system below its metal-insulator
+transition temperature and in this state the material exhibits various
+dynamical phenomena such as relaxation of resistivity, dependence of
+resistivity on cooling rate and rejuvenation of the material after ageing.
+These phenomena signal that the phase separated state of NdNiO$_3$ is not in
+thermodynamic equilibrium and we conjecture that it consists of supercooled
+paramagnetic metallic and antiferromagnetic insulating phases. The supercooled
+phases are metastable and they switch over to the insulating equilibrium state
+stochastically and this can account for the slow dynamics observed in our
+system. We also verify the predictive power of our model by simulating the
+result of a new experiment and confirming it by actual measurements.",0811.1836v1
+2008-11-26,"Does Mesophase Ag4+xPb2O6-z (0 <= x <= 1, 0,5 <= z <= 0,75) Appeal for a Point Contact ATc Superconductivity?","Weakly compacted fine particles of Ag4+xPb2O6-z which is iso-structural with
+Bystroem-Evers oxide Ag5Pb2O6 exhibit a novel class of physical properties,
+which includes an appearance of diamagnetism at t < 78 degrees Celsius, with
+corresponding absence of electric resistance, both events sounding for possible
+superconductivity. Weak compaction was performed by controlled pressing of
+introductory components Ag2O and PbO2. Pellets were heated from room
+temperature in an evacuated chamber, and solid state reaction proceeded at
+340-350 degrees Celsius in an oxygen atmosphere released by reaction itself (60
+< p < 100 mbar). Electric and magnetic properties appealing for an ambient
+temperature superconductivity may be attributed to scattering processes
+indicated by tunnelling of Ag-Ag clusters between states localized on the point
+contacts formed between adjacent particles. As compared to the work on the
+subject during past two decades, reproducibility of output data is
+satisfactory, and their correlations to the input preparation conditions appear
+as to be conclusive.",0811.4352v1
+2008-12-08,Orbital reconstruction and two-dimensional electron gas at the LaAlO3/SrTiO3 interface,"Conventional two-dimensional electron gases are realized by engineering the
+interfaces between semiconducting compounds. In 2004, Ohtomo and Hwang
+discovered that an electron gas can be also realized at the interface between
+large gap insulators made of transition metal oxides [1]. This finding has
+generated considerable efforts to clarify the underlying microscopic mechanism.
+Of particular interest is the LaAlO3/SrTiO3 system, because it features
+especially striking properties. High carrier mobility [1], electric field
+tuneable superconductivity [2] and magnetic effects [3], have been found. Here
+we show that an orbital reconstruction is underlying the generation of the
+electron gas at the LaAlO3/SrTiO3 n-type interface. Our results are based on
+extensive investigations of the electronic properties and of the orbital
+structure of the interface using X-ray Absorption Spectroscopy. In particular
+we find that the degeneracy of the Ti 3d states is fully removed, and that the
+Ti 3dxy levels become the first available states for conducting electrons.",0812.1444v1
+2008-12-31,Structural distortion and frustrated magnetic interactions in the layered copper oxychloride [CuCl]LaNb(2)O(7),"We present a computational study of the layered copper oxychloride
+[CuCl]LaNb(2)O(7) that has been recently proposed as a spin-1/2 frustrated
+square lattice compound. Our results evidence an orbitally degenerate ground
+state for the reported tetragonal crystal structure and reveal a
+Jahn-Teller-type structural distortion. This distortion heavily changes the
+local environment of copper -- CuO(2)Cl(2) plaquettes are formed instead of
+CuO(2)Cl(4) octahedra -- and restores the single-orbital scenario typical for
+copper oxides and oxyhalides. The calculated distortion is consistent with the
+available diffraction data and the experimental results on the electric field
+gradients for the Cu and Cl sites. The band structure suggests a complex
+three-dimensional spin model with the interactions up to the fourth neighbors.
+Despite the layered structure of (CuCl)LaNb(2)O(7), the spin system has
+pronounced one-dimensional features. Yet, sizable interchain interactions lead
+to the strong frustration and likely cause the spin-gap behavior. Computational
+estimates of individual exchange couplings are in qualitative agreement with
+the experimental data.",0901.0154v2
+2009-02-09,Unconventional metamagnetic electron states in orbital band systems,"We extend the study of the Fermi surface instability of the Pomeranchuk type
+into systems with orbital band structures, which are common features in
+transition metal oxides. Band hybridization significantly shifts the spectra
+weight of the Landau interactions from the conventional s-wave channel to
+unconventional non-s-wave channels, which results in anisotropic (nematic)
+Fermi surface distortions even with ordinary interactions in solids. The
+Ginzburg-Landau free energy is constructed by coupling the charge-nematic,
+spin-nematic and ferromagnetic order parameters together, which shows that
+nematic electron states can be induced by metamagnetism. The connection between
+this mechanism to the anisotropic metamagnetc states observed in
+Sr$_3$Ru$_2$O$_7$ at high magnetic fields is studied in a multi-band Hubbard
+model with the hybridized quasi-one dimensional $d_{xz}$ and $d_{yz}$-bands.",0902.1337v3
+2009-02-09,Superexchange Interaction and Magnetic Moment in Antiferromagnetic High-T_c Copper-oxide Superconductors,"Extensive Cu-NMR studies on multilayered high-Tc cuprates have deduced the
+following results;(1) Antiferromagnetic (AFM) moment M_{AFM} is decreased with
+doping, regardless of the number of CuO_2 layers n, and collapses around a
+carrier density N_h = 0.17. (2) The AFM ordering temperature is enhanced as the
+out-of-plane coupling J_{out} increases with increasing n. (3) The in-plane
+superexchange J_{in} is invariant with doping, but is even increased. (4) The
+dome shape of T_c from the underdoped to the overdoped regime with a maximum
+T_c at N_h = 0.22 does not depend on n, but its maximum value of T_c seems to
+depend on n moderately. The present results strongly suggest that the AFM
+interaction plays the vital role as the glue for the Cooper pairs, which will
+lead us to a genuine understanding of why the T_c of cuprate superconductors is
+so high.",0902.1381v1
+2009-02-10,Application of Secondary Neutral Mass Spectrometry in the investigation of doped perovskites,"Electromagnetic properties of doped perovskites depend sensitively on the
+doping level. Both the superconducting transition temperature of
+Bi2Sr2Ca(Pr)Cu2O8+d compounds and the magnetic and electronic transport
+properties of La(Sr)Co(Fe)O3 perovskites change dramatically with the doping
+level. Apart from doping, oxygen deficiency is influenced by the details of
+preparation processes such as calcination and sintering. Simultaneous
+determination of constituents is of crucial importance from sample
+characterization point of view. Quantitative analysis of perovskite oxides can
+be performed by Secondary Neutral Mass Spectrometry (SNMS) which is a suitable
+technique to measure the chemical composition of almost any sample because the
+flux of atoms sputtered from the sample is representative of the stoichiometry
+of the top-most layers. The composition and oxygen content of
+Bi2Sr2Ca0.86Pr0.14Cu2O8.4 and La1-xSrxCo0.975Fe0.025O3-d, where 0<x<0.5, were
+determined by SNMS. The results show that the method is equally applicable for
+insulating and conducting compounds. The observed electromagnetic properties
+reflect well the compositions obtained experimentally.",0902.1649v1
+2009-02-18,The energy scale behind the metallic behaviors in low-density Si-MOSFETs,"We show that the unexpected metallic behavior (the so-called two-dimensional
+metal-insulator transition) observed in low-density Silicon
+metal-oxide-semiconductor field-effect transistors (Si-MOSFETs) is controlled
+by a unique characteristic energy scale, the polarization energy. On one hand,
+we perform Quantum Monte Carlo calculations of the energy needed to polarize
+the two dimensional electron gas at zero temperature, taking into account
+Coulomb interactions, valley degeneracy and electronic mobility (disorder). On
+the other hand, we identify the characteristic energy scale controlling the
+physics in eight different sets of experiments. We find that our {\it
+ab-initio} polarization energies (obtained without any adjustable parameters)
+are in perfect agreement with the observed characteristic energies for all
+available data, both for the magnetic field and temperature dependence of the
+resistivities. Our results put strong constraints on possible mechanisms
+responsible for the metallic behavior. In particular, there are strong
+indications that the system would eventually become insulating at low enough
+temperature.",0902.3171v3
+2009-03-14,Electron coherent and incoherent pairing instabilities in inhomogeneous bipartite and nonbipartite nanoclusters,"Exact calculations of collective excitations and charge/spin (pseudo)gaps in
+an ensemble of bipartite and nonbipartite clusters yield level crossing
+degeneracies, spin-charge separation, condensation and recombination of
+electron charge and spin, driven by interaction strength, inter-site couplings
+and temperature. Near crossing degeneracies, the electron configurations of the
+lowest energies control the physics of electronic pairing, phase separation and
+magnetic transitions. Rigorous conditions are found for the smooth and dramatic
+phase transitions with competing stable and unstable inhomogeneities.
+Condensation of electron charge and spin degrees at various temperatures offers
+a new mechanism of pairing and a possible route to superconductivity in
+inhomogeneous systems, different from the BCS scenario. Small bipartite and
+frustrated clusters exhibit charge and spin inhomogeneities in many respects
+typical for nano and heterostructured materials. The calculated phase diagrams
+in various geometries may be linked to atomic scale experiments in high T$_c$
+cuprates, manganites and other concentrated transition metal oxides.",0903.2586v1
+2009-03-16,Superconductivity and quantum oscillations in crystalline Bi nanowires,"While bulk bismuth (Bi) is a semimetal, we have found clear evidence of
+superconductivity in a crystalline 72 nm diameter Bi nanowire below 1.3 K. In a
+parallel magnetic field (H), the residual resistance of the nanowire below Tc
+displays periodic oscillations with H, and the period corresponds to the
+superconducting flux quantum. This result provides evidence that the
+superconductivity comes from the interface shell between Bi and the surface
+oxide. In a perpendicular H, the resistance in the superconducting state shows
+Shubnikov-de Haas (SdH) oscillations, a signature of a normal metal. These
+results indicate a novel coexistence of Bosonic and Fermionic states in the
+surface shell of nanowires.",0903.2855v1
+2009-03-23,Spin-like susceptibility of metallic and insulating thin films at low temperature,"Susceptibility measurements of patterned thin films at sub-K temperatures
+were carried out using a scanning SQUID microscope that can resolve signals
+corresponding to a few hundred Bohr magnetons. Several metallic and insulating
+thin films, even oxide-free Au films, show a paramagnetic response with a
+temperature dependence that indicates unpaired spins as the origin. The
+observed response exhibits a measurable out-of-phase component, which implies
+that these spins will create 1/f-like magnetic noise. The measured spin density
+is consistent with recent explanations of low frequency flux noise in SQUIDs
+and superconducting qubits in terms of spin fluctuations, and suggests that
+such unexpected spins may be even more ubiquitous than already indicated by
+earlier measurements. Our measurements set several constraints on the nature of
+these spins.",0903.3748v2
+2009-03-30,Room-temperature ferromagnetism in the mixtures of the TiO2 and Co3O4 powders,"We report here the observation of ferromagnetism (FM) at 300 K in mixtures of
+TiO2 and Co3O4 powders despite the antiferromagnetic and diamagnetic character
+of both oxides respectively. The ferromagnetic behavior is found in the early
+stages of reaction and only for TiO2 in anatase structure; no FM is found for
+identical samples prepared with rutile-TiO2. Optical spectroscopy and X-ray
+absorption spectra confirm a surface reduction of octahedral Co+3->Co+2 in the
+mixtures which is in the origin of the observed magnetism",0903.5214v1
+2009-04-08,Spin--orbital physics in transition metal oxides,"We present the main features of the spin-orbital superexchange which
+describes the magnetic and optical properties of Mott insulators with orbital
+degrees of freedom. In contrast to the SU(2) symmetry of spin superexchange,
+the orbital part of the superexchange obeys the lower cubic symmetry of the
+lattice and is intrinsically frustrated. This intrinsic frustration and
+spin-orbital entanglement induce enhanced quantum fluctuations, and we point
+out a few situations where this leads to disordered states. Strong coupling
+between the spin and orbital degrees of freedom is discussed on the example of
+the $R$VO$_3$ perovskites, with $R$ standing for rare-earth ion, La,...,Lu. We
+explain the observed evolution of the orbital $T_{\rm OO}$ and N\'eel $T_{N1}$
+transition temperature in the $R$VO$_3$ series with decreasing ionic radius
+$r_R$. A few open problems and the current directions of research in the field
+of spin-orbital physics are pointed out.",0904.1297v1
+2009-05-01,Directional field-induced metallization of quasi-one-dimensional Li$_{0.9}$Mo$_6$O$_{17}$,"We report a detailed magnetotransport study of the highly anisotropic
+quasi-one-dimensional oxide Li$_{0.9}$Mo$_6$O$_{17}$ whose in-chain electrical
+resistivity diverges below a temperature $T_{\rm min} \sim$ 25 K. For $T <
+T_{\rm min}$, a magnetic field applied parallel to the conducting chain induces
+a large negative magnetoresistance and ultimately, the recovery of a metallic
+state. We show evidence that this insulator/metal crossover is a consequence of
+field-induced suppression of a density-wave gap in a highly one-dimensional
+conductor. At the highest fields studied, there is evidence for the possible
+emergence of a novel superconducting state with an onset temperature $T_c >$ 10
+K.",0905.0098v1
+2009-08-02,Spin-dependent transport in nanocomposite C:Co films,"The magneto-transport properties of nanocomposite C:Co (15 and 40 at.% Co)
+thin films are investigated. The films were grown by ion beam co-sputtering on
+thermally oxidized silicon substrates in the temperature range from 200 to 500
+degC. Two major effects are reported: (i) a large anomalous Hall effect
+amounting to 2 \mu ohm cm, and (ii) a negative magnetoresistance. Both the
+field-dependent resistivity and Hall resistivity curves coincide with the
+rescaled magnetization curves, a finding that is consistent with spin-dependent
+transport. These findings suggest that C:Co nanocomposites are promising
+candidates for carbon-based Hall sensors and spintronic devices.",0908.0127v1
+2009-08-24,Half-Skyrmion theory for high-temperature superconductivity,"We review the half-Skyrmion theory for copper-oxide high-temperature
+superconductivity. In the theory, doped holes create a half-Skyrmion spin
+texture which is characterized by a topological charge. The formation of the
+half-Skyrmion is described in the single hole doped system, and then the
+half-Skyrmion excitation spectrum is compared with the angle-resolved
+photoemission spectroscopy results in the undoped system. Multi-half-Skyrmion
+configurations are studied by numerical simulations. We show that
+half-Skyrmions carry non-vanishing topological charge density below a critical
+hole doping concentration \sim 30% even in the absence of antiferromagnetic
+long-range order. The magnetic structure factor exhibits incommensurate peaks
+in stripe ordered configurations of half-Skyrmions and anti-half-Skyrmions. The
+interaction mediated by half-Skyrmions leads to d_{x^2-y^2}-wave
+superconductivity. We also describe pseudogap behavior arising from the
+excitation spectrum of a composite particle of a half-Skyrmion and doped hole.",0908.3385v1
+2009-09-15,Anisotropy of the low-temperature magnetostriction of Sr3Ru2O7,"We use high-resolution capacitive dilatometry to study the low-temperature
+linear magnetostriction of the bilayer ruthenate Sr$_3$Ru$_2$O$_7$ as a
+function of magnetic field applied perpendicular to the ruthenium-oxide planes
+($B\parallel c$). The relative length change $\Delta L(B)/L$ is detected either
+parallel or perpendicular to the c-axis close to the metamagnetic region near
+B=8 T. In both cases, clear peaks in the coefficient $\lambda(B)=d(\Delta
+L/L)/dB$ at three subsequent metamagnetic transitions are observed. For $\Delta
+L\perp c$, the third transition at 8.1 T bifurcates at temperatures below 0.5
+K. This is ascribed to the effect of an in-plane uniaxial pressure of about 15
+bar, unavoidable in the dilatometer, which breaks the original fourfold
+in-plane symmetry.",0909.2731v1
+2009-09-28,Exciton doublet in the Mott-Hubbard LiCuVO$_4$ insulator identified by spectral ellipsometry,"Spectroscopic ellipsometry was used to study the dielectric function of
+LiCuVO$_{4}$, a compound comprised of chains of edge-sharing CuO$_4$
+plaquettes, in the spectral range (0.75 - 6.5) eV at temperatures (7-300) K.
+For photon polarization along the chains, the data reveal a weak but
+well-resolved two-peak structure centered at 2.15 and 2.95 eV whose spectral
+weight is strongly enhanced upon cooling near the magnetic ordering
+temperature. We identify these features as an exciton doublet in the
+Mott-Hubbard gap that emerges as a consequence of the Coulomb interaction
+between electrons on nearest and next-nearest neighbor sites along the chains.
+Our results and methodology can be used to address the role of the long-range
+Coulomb repulsion for compounds with doped copper-oxide chains and planes.",0909.5157v1
+2010-02-04,Origin of half-semimetallicity induced at interfaces of C-BN heterostructures,"First-principles density functional calculations are performed in C-BN
+heterojunctions. It is shown that the magnetism of the edge states in zigzag
+shaped graphene strips and polarity effects in BN strips team up to give a spin
+asymmetric screening that induces half-semimetallicity at the interface, with a
+gap of at least a few tenths of eV for one spin orientation and a tiny gap of
+hundredths of eV for the other. The dependence with ribbon widths is discussed,
+showing that a range of ribbon widths is required to obtain
+half-semimetallicity. These results open new routes for tuning electronic
+properties at nanointerfaces and exploring new physical effects similar to
+those observed at oxide interfaces, in lower dimensions.",1002.1018v1
+2010-02-24,Magnetic Structure of CaBaCo4O7: Lifting of Geometrical Frustration towards Ferrimagnetism,"CaBaCo4O7 represents a new class of ferrimagnets whose structure is built up
+of CoO4 tetrahedra only, similarly to other members LnBaCo4O7 of the 114
+series, forming an alternate stacking of kagome and triangular layers. Neutron
+powder diffraction reveals, that this compound exhibits the largest distortion
+within the 114 series, characterized by a strong buckling of the kagome layers.
+Differently from all other members it shows charge ordering, with Co2+ sitting
+on two sites (Co2, Co3) and mixed valent cobalt Co3+/Co2+L sitting on two other
+sites (Co1, Co4). The unique ferrimagnetic structure of this cobaltite at 4 K
+can be described as the assemblage of ferrimagnetic triple chains (Co1 Co2 Co3)
+running perpendicular to the kagome layers, ferromagnetically coupled within
+the layers, and antiferromagnetically coupled with a fourth cobalt species Co4.
+The lifting of the geometrical frustration towards ferrimagnetism, which
+appears in spite of the triangular topology of the cobalt lattice, is explained
+by the very large structural distortion, charge ordering phenomena and large
+cobalt valence compared to other LnBaCo4O7 oxides.",1002.4544v1
+2010-03-08,Origin of the magnetoelectric coupling effect in Pb(Zr0.2Ti0.8)O3/La0.8Sr0.2MnO3 multiferroic heterostructures,"The electronic valence state of Mn in Pb(Zr0.2Ti0.8)O3/La0.8Sr0.2MnO3
+multiferroic heterostructures is probed by near edge x-ray absorption
+spectroscopy as a function of the ferroelectric polarization. We observe a
+temperature independent shift in the absorption edge of Mn associated with a
+change in valency induced by charge carrier modulation in the La0.8Sr0.2MnO3,
+demonstrating the electronic origin of the magnetoelectric effect.
+Spectroscopic, magnetic, and electric characterization shows that the large
+magnetoelectric response originates from a modified interfacial spin
+configuration, opening a new pathway to the electronic control of spin in
+complex oxide materials.",1003.1752v1
+2010-06-07,A Robust Approach for the Growth of Epitaxial Spinel Ferrite Films,"Heteroepitaxial spinel ferrites NiFe2O4 and CoFe2O4 films have been prepared
+by pulsed laser deposition (PLD) at various temperatures (175 - 690 {\deg}C)
+under ozone/oxygen pressure of 10 mTorr. Due to enhanced kinetic energy of
+ablated species at low pressure and enhanced oxidation power of ozone, epitaxy
+has been achieved at significantly lower temperatures than previously reported.
+Films grown at temperature below 550 {\deg}C show a novel growth mode, which we
+term ""vertical step-flow"" growth mode. Epitaxial spinel ferrite films with
+atomically flat surface over large areas and enhanced magnetic moment can be
+routinely obtained. Interestingly, the growth mode is independent of the nature
+of substrates (spinel MgAl2O4, perovskite SrTiO3, and rock salt MgO) and film
+thicknesses. The underlying growth mechanism is discussed.",1006.1161v1
+2010-08-18,Field-dependent low-field enhancement in effective paramagnetic moment with nano-scaled Co3O4,"Paramagnetic (PM) properties of columnar cobaltosic oxide (Co3O4)
+nanoparticles, about 75 nm in diameter, have been investigated by magnetization
+measurements at T > TN = 39 K. In zero or low applied field, the effective PM
+moment per formula unit (FU), Mu_eff, enhances significantly from the bulk
+value of 4.14 Mu_B/FU. It decreases asymptotically from 5.96 Mu_B/FU at Happ =
+50 Oe down to 4.21 Mu_B/FU as the applied field increases to Happ = 10 kOe. The
+field dependent PM properties are explained by a structural inversion, from the
+normal spinel (spin-only moment ~ 3.9 Mu_B/FU) to the inverse spinel structure
+(spin-only moment ~ 8.8 Mu_B/FU). The structural inversion is reversible with
+the variation of the applied field. The lattice structure becomes almost 100%
+normal spinel in the high field exceeding 10 kOe, as revealed by the magnitude
+of the effective PM moment. The reversible, field dependent structure inversion
+is an important property with promising application potential. It is
+interesting for the future investigations.",1008.3156v1
+2010-09-24,Control of Correlations in Sr4V2O6Fe2As2 by Chemical Stoichiometry,"We show using a combination of powder X-ray and neutron diffraction, first
+principles calculations, temperature- and field-dependent magnetization, heat
+capacity and resistivity data that the superconducting behavior of
+`Sr$_4$V$_2$O$_6$Fe$_2$As$_2$' is dependent on synthesis conditions,
+particularly, heating profiles result in unintentional chemical doping. This
+compound can be tuned from a state in which the vanadium electrons are
+itinerant with a high electronic density of states, to a state where the
+vanadium-oxide layers are insulating and presumably antiferromagnetic.",1009.4911v1
+2010-12-17,Observation of Andreev bound states at spin-active interfaces,"We report on high-resolution differential conductance experiments on
+nanoscale superconductor/ferromagnet tunnel junctions with ultra-thin oxide
+tunnel barriers. We observe subgap conductance features which are symmetric
+with respect to bias, and shift according to the Zeeman energy with an applied
+magnetic field. These features can be explained by resonant transport via
+Andreev bound states induced by spin-active scattering at the interface. From
+the energy and the Zeeman shift of the bound states, both the magnitude and
+sign of the spin-dependent interfacial phase shifts between spin-up and
+spin-down electrons can be determined. These results contribute to the
+microscopic insight into the triplet proximity effect at spin-active
+interfaces.",1012.3867v2
+2010-12-31,Orbital reflectometry,"The occupation of d-orbitals controls the magnitude and anisotropy of the
+inter-atomic electron transfer in transition metal oxides and hence exerts a
+key influence on their chemical bonding and physical properties. Atomic-scale
+modulations of the orbital occupation at surfaces and interfaces are believed
+to be responsible for massive variations of the magnetic and transport
+properties, but could thus far not be probed in a quantitative manner. Here we
+show that it is possible to derive quantitative, spatially resolved orbital
+polarization profiles from soft x-ray reflectivity data, without resorting to
+model calculations. We demonstrate that the method is sensitive enough to
+resolve differences of 3 % in the occupation of Ni e_g orbitals in adjacent
+atomic layers of a LaNiO3-LaAlO3 superlattice, in good agreement with ab-initio
+electronic-structure calculations. The possibility to quantitatively correlate
+theory and experiment on the atomic scale opens up many new perspectives for
+orbital physics in d-electron materials.",1101.0238v1
+2011-01-27,Magnetic excitations in one-dimensional spin-orbital models,"We study the dynamics and thermodynamics of one-dimensional spin-orbital
+models relevant for transition metal oxides. We show that collective spin,
+orbital, and combined spin-orbital excitations with infinite lifetime can
+exist, if the ground state of both sectors is ferromagnetic. Our main focus is
+the case of effectively ferromagnetic (antiferromagnetic) exchange for the spin
+(orbital) sector, respectively, and we investigate the renormalization of spin
+excitations via spin-orbital fluctuations using a boson-fermion representation.
+We contrast a mean-field decoupling approach with results obtained by treating
+the spin-orbital coupling perturbatively. Within the latter self-consistent
+approach we find a significant increase of the linewidth and additional
+structures in the dynamical spin structure factor as well as Kohn anomalies in
+the spin-wave dispersion caused by the scattering of spin excitations from
+orbital fluctuations. Finally, we analyze the specific heat c(T) by comparing a
+numerical solution of the model obtained by the density-matrix renormalization
+group with perturbative results. At low temperatures T we find numerically c(T)
+T pointing to a low-energy effective theory with dynamical critical exponent
+z=1.",1101.5301v1
+2011-01-30,Controlling electrostatic co-assembly using ion-containing copolymers : from surfactants to nanoparticles,"In this review, we address the issue of the electrostatic complexation
+between charged-neutral diblock copolymers and oppositely charged nanocolloids.
+We show that nanocolloids such as surfactant micelles and iron oxide magnetic
+nanoparticles share similar properties when mixed with charged-neutral
+diblocks. Above a critical charge ratio, core-shell hierarchical structures
+form spontaneously under direct mixing conditions. The core-shell structures
+are identified by a combination of small-angle scattering techniques and
+transmission electron microscopy. The formation of multi-level objects is
+driven by the electrostatic attraction between opposite charges and by the
+release of the condensed counterions. Alternative mixing processes inspired
+from molecular biology are also described. The protocols applied here consist
+in screening the electrostatic interactions of the mixed dispersions, and then
+removing the salt progressively as example by dialysis. With these techniques,
+the oppositely charged species are intimately mixed before they can interact,
+and their association is monitored by the desalting kinetics. As a result,
+sphere- and rod-like aggregates with remarkable superparamagnetic and stability
+properties are obtained. These findings are discussed in the light of a new
+paradigm which deals with the possibility to use inorganic nanoparticles as
+building blocks for the design and fabrication of supracolloidal assemblies
+with enhanced functionalities.",1101.5821v1
+2011-03-15,Spin filling of valley-orbit states in a silicon quantum dot,"We report the demonstration of a low-disorder silicon
+metal-oxide-semiconductor (Si MOS) quantum dot containing a tunable number of
+electrons from zero to N=27. The observed evolution of addition energies with
+parallel magnetic field reveals the spin filling of electrons into valley-orbit
+states. We find a splitting of 0.10 meV between the ground and first excited
+states, consistent with theory and placing a lower bound on the valley
+splitting. Our results provide optimism for the realization in the near future
+of spin qubits based on silicon quantum dots.",1103.2895v2
+2011-03-15,Oxygen hyperstoichiometric hexagonal ferrite CaBaFe4O7+δ(δ \approx 0.14) : coexistence of ferrimagnetism and spin glass behavior,"An oxygen hyperstoichiometric ferrite CaBaFe4O7+\delta (\delta \approx 0.14)
+has been synthesized using ""soft"" reduction of CaBaFe4O8. Like the oxygen
+stoichiometric ferrimagnet CaBaFe4O7, this oxide also keeps the hexagonal
+symmetry (space group: P63mc), and exhibits the same high Curie temperature of
+270 K. However, the introduction of extra oxygen into the system weakens the
+ferrimagnetic interaction significantly at the cost of increased magnetic
+frustration at low temperature. Moreover, this canonical spin glass (Tg ~ 166
+K) exhibits an intriguing cross-over from de Almeida-Thouless type to
+Gabay-Toulouse type critical line in the field temperature plane above a
+certain field strength, which can be identified as the anisotropy field. Domain
+wall pinning is also observed below 110 K. These results are interpreted on the
+basis of cationic disordering on the iron sites.",1103.2939v1
+2011-03-17,Magneto-Transport Properties of Exfoliated Graphene on GaAs,"We studied the magneto-transport properties of graphene prepared by
+exfoliation on a III V semiconductor substrate. Tuneability of the carrier
+density of graphene was achieved by using a doped GaAs substrate as a
+back-gate. A GaAs/AlAs multilayer, designed to render the exfoliated graphene
+flakes visible, also provides the required back-gate insulation. Good
+tuneability of the graphene carrier density is obtained, and the typical Dirac
+resistance characteristic is observed despite the limited height of the
+multilayer barrier compared to the usual SiO2 oxide barrier on doped silicon.
+In a magnetic field weak localization effects as well as the quantum Hall
+effect of a graphene monolayer are studied.",1103.3367v4
+2011-05-31,Octahedral rotation-induced ferroelectricity in cation ordered perovskites,"Increasing demands for electric field-tunable electric, magnetic, and orbital
+(EMO) materials has renewed interests in ferroelectricity and its coupling to
+EMO properties in complex perovskite oxides. The historic design strategy to
+achieve a spontaneous polarization involves the incorporation of second-order
+Jahn-Teller (SOJT) active cations. The challenge, however, is that this
+mechanism is limited to specific chemistries and the polar distortions that
+arise are largely decoupled from EMO properties, limiting their use as
+field-tunable multifunctional technology materials. Here we report the
+crystal-chemistry criteria which circumvents those restrictions and enables the
+rational design of new materials displaying octahedral rotation-induced
+ferroelectricity - an innovative route to realize electric polarization without
+the need for SOJT cations - from non-polar building blocks. The strategy
+exploits the centric octahedral rotation patterns, which strongly couple to EMO
+properties, and cation ordering commonly observed in non-polar $AB$O$_3$
+perovskites. By uniting switchable electric polarizations to the connectivity
+of the transition-metal oxygen octahedra, electric-field control over materials
+properties is possible.",1106.0049v3
+2011-06-02,Microscopic Study of Electronic and Magnetic Properties for Ir Oxide,"The exact diagonalization and the variational cluster approximation (VCA) are
+used to study the nature of a novel Mott insulator induced by a strong
+spin-orbit coupling for a two-dimensional three-band Hubbard model consisting
+of the $t_{2g}$ manifold of $5d$ orbitals. To characterize the ground state, we
+introduce a local Kramer's doublet which can represent a state with effective
+angular momentum $J_{\rm eff}=|{\bm S}-{\bm L}|=1/2$ as well as spin $S=1/2$.
+Our systematic study of the pseudo-spin structure factor defined by the
+Kramer's doublet shows that the $J_{\rm eff}=1/2$ Mott insulator is smoothly
+connected to the $S=1/2$ Mott insulator. Using the Kramer's doublet as a
+variational state for the VCA, we examine the one-particle excitations for the
+Mott insulating phase. These results are compared with recent experiments on
+Sr$_2$IrO$_4$.",1106.0413v1
+2011-06-12,Electrodynamics of Correlated Electron Materials,"We review studies of the electromagnetic response of various classes of
+correlated electron materials including transition metal oxides, organic and
+molecular conductors, intermetallic compounds with $d$- and $f$-electrons as
+well as magnetic semiconductors. Optical inquiry into correlations in all these
+diverse systems is enabled by experimental access to the fundamental
+characteristics of an ensemble of electrons including their self-energy and
+kinetic energy. Steady-state spectroscopy carried out over a broad range of
+frequencies from microwaves to UV light and fast optics time-resolved
+techniques provide complimentary prospectives on correlations. Because the
+theoretical understanding of strong correlations is still evolving, the review
+is focused on the analysis of the universal trends that are emerging out of a
+large body of experimental data augmented where possible with insights from
+numerical studies.",1106.2309v1
+2011-06-13,Iron-chalcogenide FeSe$_{0.5}$Te$_{0.5}$ coated superconducting tapes for high field applications,"The high upper critical field characteristic of the recently discovered
+iron-based superconducting chalcogenides opens the possibility of developing a
+new type of non-oxide high-field superconducting wires. In this work, we
+utilize a buffered metal template on which we grow a textured
+FeSe$_{0.5}$Te$_{0.5}$ layer, an approach developed originally for high
+temperature superconducting coated conductors. These tapes carry high critical
+current densities (>1$\times10^{4}$A/cm$^{2}$) at about 4.2K under magnetic
+field as high as 25 T, which are nearly isotropic to the field direction. This
+demonstrates a very promising future for iron chalcogenides for high field
+applications at liquid helium temperatures. Flux pinning force analysis
+indicates a point defect pinning mechanism, creating prospects for a
+straightforward approach to conductor optimization.",1106.2466v1
+2011-08-15,Polar octahedral rotations: a path to new multifunctional materials,"Perovskite ABO$_3$ oxides display an amazing variety of phenomena that can be
+altered by subtle changes in the chemistry and internal structure, making them
+a favorite class of materials to explore the rational design of novel
+properties. Here we highlight a recent advance in which rotations of the BO$_6$
+octahedra give rise to a novel form of ferroelectricity -- hybrid improper
+ferroelectricity. Octahedral rotations also strongly influence other
+structural, magnetic, orbital, and electronic degrees of freedom in perovskites
+and related materials. Octahedral rotation-driven ferroelectricity consequently
+has the potential to robustly control emergent phenomena with an applied
+electric field. The concept of `functional' octahedral rotations is introduced
+and the challenges for materials chemistry and the possibilities for new
+rotation-driven phenomena in multifunctional materials are explored.",1108.2915v2
+2011-09-07,Possible interaction driven topological phases in (111) bilayers of LaNiO3,"We use the variational mean-field approach to systematically study the phase
+diagram of a bilayer heterostructure of the correlated transition metal oxide
+LaNiO3, grown along the (111) direction. The Ni 3+ ions with d7 (or eg1)
+configuration form a buckled honeycomb lattice. We show that as a function of
+the strength of the on-site interactions, various topological phases emerge. In
+the presence of a reasonable size of the Hund's coupling, as the correlation is
+tuned from intermediate to strong, the following sequence of phases is found:
+(1) a Dirac half-semimetal phase, (2) a quantum anomalous hall insulator (QAHI)
+phase with Chern number one, and (3) a ferromagnetic nematic phase breaking the
+lattice point group symmetry. The spin-orbit couplings and magnetism are both
+dynamically generated in the QAHI phase.",1109.1551v2
+2011-09-09,Conditions determining the morphology and nanoscale magnetism of Co nanoparticles: Experimental and numerical studies,"Co-based nanostructures ranging from core-shell to hollow nanoparticles were
+produced by varying the reaction time and the chemical environment during the
+thermal decomposition of Co2(CO)8. Both structural characterization and kinetic
+model simulation illustrate that the diffusivities of Co and oxygen determine
+the growth ratio and the final morphology of the nanoparticles. Exchange
+coupling between Co and Co-oxide in core/shell nanoparticles induced a shift of
+field-cooled hysteresis loops that is proportional to the shell thickness, as
+verified by numerical studies. The increased nanocomplexity when going from
+core/shell to hollow particles, also leads to the appearance of hysteresis
+above 300 K due to an enhancement of the surface anisotropy resulting from the
+additional spin-disordered surfaces.",1109.2024v1
+2011-10-07,Overlapping-gate architecture for silicon Hall bar MOSFET devices in the low electron density and high magnetic field regime,"A common issue in low temperature measurements of enhancement-mode
+metal-oxide-semiconductor (MOS) field-effect transistors (FETs) in the low
+electron density regime is the high contact resistance dominating the device
+impedance. In that case a voltage bias applied across the source and drain
+contact of a Hall bar MOSFET will mostly fall across the contacts (and not
+across the channel) and therefore magneto-transport measurements become
+challenging. However, from a physical point of view, the study of MOSFET
+nanostructures in the low electron density regime is very interesting (impurity
+limited mobility [1], carrier interactions [2,3] and spin-dependent transport
+[4]) and it is therefore important to come up with solutions [5,6] that work
+around the problem of a high contact resistance in such devices (c.f. Fig. 1
+(a)).",1110.1418v1
+2012-02-20,Correlation effects on 3D topological phases: from bulk to boundary,"Topological phases of quantum matter defy characterization by conventional
+order parameters but can exhibit quantized electro-magnetic response and/or
+protected surface states. We examine such phenomena in a model for
+three-dimensional correlated complex oxides, the pyrochlore iridates. The model
+realizes interacting topological insulators with and without time-reversal
+symmetry, and topological Weyl semimetals. We use cellular dynamical mean field
+theory, a method that incorporates quantum-many-body effects and allows us to
+evaluate the magneto-electric topological response coefficient in correlated
+systems. This invariant is used to unravel the presence of an interacting axion
+insulator absent within a simple mean field study. We corroborate our bulk
+results by studying the evolution of the topological boundary states in the
+presence of interactions. Consequences for experiments and for the search for
+correlated materials with symmetry-protected topological order are given.",1202.4460v2
+2012-02-23,Quantum-fluctuation effects in transport properties of superconductors above the paramagnetic limit,"We study the transport in ultrathin disordered film near the quantum critical
+point induced by the Zeeman field. We calculate corrections to the normal state
+conductivity due to quantum pairing fluctuations. The fluctuation-induced
+transport is mediated by virtual rather than real quasi-particles. We find that
+at zero temperature, where the corrections come from purely quantum
+fluctuations, the Aslamazov-Larkin paraconductivity term, the Maki-Thompson
+interference contribution and the density of states effects are all of the same
+order. The total correction leads to the negative magnetoresistance. This
+result is in qualitative agreement with the recent transport observations in
+the parallel magnetic field of the homogeneously disordered amorphous films and
+superconducting two-dimensional electron gas realized at the oxide interfaces.",1202.5082v1
+2012-03-08,Covalent functionalization of strained graphene,"Enhancement of the chemical activity of graphene is evidenced by
+first-principles modelling of chemisorption of the hydrogen, fluorine, oxygen
+and hydroxyl groups on strained graphene. For the case of negative strain or
+compression, chemisorption of the single hydrogen, fluorine or hydroxyl group
+is energetically more favourable than those of their pairs on different
+sublattices. This behaviour stabilizes the magnetism caused by the
+chemisorption being against its destruction by the pair formations. Initially
+flat, compressed graphene is shown to buckle spontaneously right after
+chemisorption of single adatoms. Unlike hydrogenation or fluorination, the
+oxidation process turns from the endothermic to exothermic for all types of the
+strain and depends on the direction of applied strains. Such properties will be
+useful in designing graphene devices utilizing functionalization as well as
+mechanical strains.",1203.1710v1
+2012-03-12,Disentangling a quantum antiferromagnet with resonant inelastic X-ray scattering,"Low-dimensional copper oxide lattices naturally manifest electronic states
+with strong short range quantum entanglement, which are known to lead to
+remarkable emergent material properties. However the nanometer scale many-body
+wavefunction is challenging to measure or manipulate in a simple way. In this
+study, X-ray induced $dd$ electronic transitions are used to suppress spin
+entanglement across a single lattice site in the spin-1/2 antiferromagnetic
+chain compound SrCuO$_2$, revealing a class of cuprate magnetic excitations
+that result from breaking the spin chain. These measurements are the first to
+employ two closely spaced X-ray resonances of copper (M$_2$ and M$_3$) as a
+form of natural 2-slit interferometer to distinguish between different types of
+electronic transition and resolve how they influence the dynamics of nearby
+spin-entangled electrons.",1203.2397v1
+2012-03-15,Temperature dependent magnetotransport around $ν$= 1/2 in ZnO heterostructures,"The sequence of prominent fractional quantum Hall states up to $\nu$=5/11
+around $\nu$=1/2 in a high mobility two-dimensional electron system confined at
+oxide heterointerface (ZnO) is analyzed in terms of the composite fermion
+model. The temperature dependence of $\Rxx$ oscillations around $\nu$=1/2
+yields an estimation of the composite fermion effective mass, which increases
+linearly with the magnetic field. This mass is of similar value to an enhanced
+electron effective mass, which in itself arises from strong electron
+interaction. The energy gaps of fractional states and the temperature
+dependence of $\Rxx$ at $\nu$=1/2 point to large residual interactions between
+composite fermions.",1203.3349v1
+2012-03-28,"Nut-charged black holes in matter-coupled N=2, D=4 gauged supergravity","Using the results of arXiv:0804.0009, where all timelike supersymmetric
+backgrounds of N=2, D=4 matter-coupled supergravity with Fayet-Iliopoulos
+gauging were classified, we construct genuine nut-charged BPS black holes in
+AdS_4 with nonconstant moduli. The calculations are exemplified for the
+SU(1,1)/U(1) model with prepotential F=-iX^0X^1. The resulting supersymmetric
+black holes have a hyperbolic horizon and carry two electric, two magnetic and
+one nut charge, which are however not all independent, but are given in terms
+of three free parameters. We find that turning on a nut charge lifts the flat
+directions in the effective black hole potential, such that the horizon values
+of the scalars are completely fixed by the charges. We also oxidize the
+solutions to eleven dimensions, and find that they generalize the geometry
+found in hep-th/0105250 corresponding to membranes wrapping holomorphic curves
+in a Calabi-Yau five-fold. Finally, a class of nut-charged Nernst branes is
+constructed as well, but these have curvature singularities at the horizon.",1203.6179v1
+2012-06-14,TiO2 as an electrostatic template for epitaxial growth of EuO on MgO(001) by reactive molecular beam epitaxy,"We investigate the initial growth modes and the role of interfacial
+electrostatic interactions of EuO epitaxy on MgO(001) by reactive molecular
+beam epitaxy. A TiO2 interfacial layer is employed to produce high quality
+epitaxial growth of EuO on MgO(001) with a 45{\deg} in plane rotation. For
+comparison, direct deposition of EuO on MgO, without the TiO2 layer shows a
+much slower time evolution in producing a single crystal film. Conceptual
+arguments of electrostatic repulsion of like-ions are introduced to explain the
+increased EuO quality at the interface with the TiO2 layer. It is shown that
+ultrathin EuO films in the monolayer regime can be produced on the TiO2 surface
+by substrate-supplied oxidation and that such films have bulk-like magnetic
+properties.",1206.2981v1
+2012-06-29,Double exchange model on triangular lattice: non-coplanar spin configuration and phase transition near quarter filling,"Unconventional anomalous Hall effect in frustrated pyrochlore oxides is
+originated from spin chirality of non-coplanar localized spins, which can also
+be induced by the competition between ferromagnetic (FM) double exchange
+interaction $J_{H}$ and antiferromagnetic superexchange interaction $J_{AF}$.
+Here truncated polynomial expansion method and Monte Carlo simulation are
+adopted to investigate the above model on two-dimensional triangular lattice.
+We discuss the influence of the range of FM-type spin-spin correlation and
+strong electron-spin correlation on the truncation error of spin-spin
+correlation near quarter filling. Two peaks of the probability distribution of
+spin-spin correlation in non-coplanar spin configuration clearly show that
+non-coplanar spin configuration is an intermediate phase between FM and
+120-degree spin phase. Near quarter filling, there is a phase transition from
+FM into non-coplanar and further into 120-degree spin phase when $J_{AF}$
+continually increases. Finally the effect of temperature on magnetic structure
+is discussed.",1206.6944v2
+2012-07-04,Kondo-like behavior near the metal-to-insulator transition of nano-scale granular aluminum,"We show that the normal state transport properties of nano-scale granular
+Aluminum films, near the metal to insulator transition, present striking
+similarities with those of Kondo systems. Those include a negative
+magneto-resistance, a minimum of resistance R at a temperature Tm in metallic
+films, a logarithmic rise at low temperatures and a negative curvature of R(T)
+at high temperatures. These normal state properties are interpreted in terms of
+spin-flip scattering of conduction electrons by local magnetic moments,
+possibly located at the metal/oxide interfaces. Their co-existence with the
+enhanced superconductivity seen in these films is discussed.",1207.0970v3
+2012-08-15,Two-dimensional electron-gas-like charge transport at magnetic Heusler alloy-SrTiO$_3$ interface,"We report remarkably low residual resistivity, giant residual resistivity
+ratio, free-electron-like Hall resistivity and high mobility ($\approx$ 10$^4$
+cm$^2$V$^{-1}$s$^{-1}$) charge transport in epitaxial films of Co$_2$MnSi and
+Co$_2$FeSi grown on (001) SrTiO$_3$. This unusual behavior is not observed in
+films deposited on other cubic oxide substrates of comparable lattice
+parameters. The scaling of the resistivity with thickness of the films allow
+extraction of interface conductance, which can be attributed to a layer of
+oxygen vacancies confined within 1.9 nm of the interface as revealed by
+atomically resolved electron microscopy and spectroscopy. The high mobility
+transport observed here at the interface of a fully spin polarized metal is
+potentially important for spintronics applications.",1208.3099v2
+2012-08-29,Floating Zone Growth of Large Single Crystals of SrFeO_3-x,"The Fe^{4+}-containing cubic perovskite phase SrFeO_3-x is of interest both
+for its high-temperature, oxygen-conducting properties as a solid oxide fuel
+cell component, and at low temperatures, where it exhibits a plethora of
+helical magnetic phases and a candidate Skyrmion lattice. However, a sequence
+of structural phase transitions encountered on cooling to room temperature has
+limited the size of single crystals. We report the floating-zone growth and
+oxygen-annealing of multiple-cubic-centimetre-sized single crystals of
+SrFeO_3-x, suitable for inelastic neutron scattering and other measurement
+techniques requiring large sample volumes.",1208.6030v1
+2012-09-18,Magneto-optical trapping of diatomic molecules,"The development of the magneto-optical trap revolutionized the fields of
+atomic and quantum physics by providing a simple method for the rapid
+production of ultracold, trapped atoms. A similar technique for producing a
+diverse set of dense, ultracold diatomic molecular species will likewise
+transform the study of strongly interacting quantum systems, precision
+measurement, and physical chemistry. We demonstrate one- and two-dimensional
+transverse laser cooling and magneto-optical trapping of the polar molecule
+yttrium (II) oxide (YO). Using a quasicycling optical transition we observe
+transverse Doppler cooling of a YO molecular beam to a temperature of 5 mK,
+limited by interaction time. With the addition of an oscillating magnetic
+quadrupole field we demonstrate a transverse magneto-optical trap and achieve
+temperatures of 2 mK.",1209.4069v1
+2012-10-12,"Layered pnictide-oxide Na$_2$Ti$_2$Pn$_2$O (Pn=As, Sb): a paradigm for spin density waves","From the first-principles calculations, we have studied the electronic and
+magnetic structures of compound Na$_2$Ti$_2$Pn$_2$O (Pn = As or Sb). We find
+that in the ground state Na$_2$Ti$_2$As$_2$O is a blocked checkerboard
+antiferromagnetic semiconductor with a small band gap of about 0.15 eV, in
+contrast, Na$_2$Ti$_2$Sb$_2$O is a bi-collinear antiferromagnetic semimetal,
+both with a small moment of about 0.5$\mu_B$ around each Ti atom. We show that
+there is a strong Fermi surface nesting in Na$_2$Ti$_2$Pn$_2$O. And we verify
+that the blocked checkerboard and bi-collinear antiferromagnetic states both
+are the spin density waves induced by the Fermi surface nesting. A tetramer
+structural distortion is found in company with the formation of a blocked
+checkerboard antiferromagnetic order, in good agreement with the experimentally
+observed commensurate structural distortion but with space group symmetry
+retained after the anomaly happening. Further analysis and discussion in
+connection with experimental observations are given as well.",1210.3481v1
+2012-12-02,Lateral spin injection and detection through electrodeposited Fe/GaAs contacts,"Efforts to achieve efficient injection of spin-polarized electrons into a
+semiconductor, a key prerequisite for developing electronics that exploit the
+electron's spin degree of freedom, have so far met with limited success. Here
+we report experimental studies of lateral spin injection and detection through
+electrodeposited Fe/GaAs tunnel contacts. We demonstrate spin injection
+efficiencies two orders of magnitude higher than for state-of-the-art contacts
+fabricated via ultra-high-vacuum methods, including those with MgO or Al2O3
+tunnel barriers. To account for this enhancement, we propose that an iron oxide
+layer that forms at the Fe/GaAs interface during electrodeposition, being
+magnetic, acts as a tunnel barrier with a spin-dependent height, presenting
+quantum spin transport calculations for such systems. This serendipitous
+discovery of greatly enhanced efficiency of spin injection into GaAs via
+electrodeposited contacts introduces a promising new direction for the
+development of practical semiconductor spintronic devices.",1212.0258v1
+2012-12-06,Quantum transport modeling of Fe/MgO/Fe magnetic tunnel junction with FeO$_{0.5}$ buffer layer: the effects of correlations,"We report \textit{ab initio} simulations of quantum transport properties of
+Fe/MgO/Fe trilayer structures with FeO$_{0.5}$ buffer iron oxide layer, where
+on-site Coulomb interaction is explicitly taken into account by local density
+approximation + Hubbard \textit{U} approach. We show that on-site Coulomb
+repulsion in the iron-oxygen layer can cause a dramatic drop of the tunnel
+magnetoresistance of the system. We present an understanding of microscopic
+details of this phenomenon, connecting it to localization of the Fermi
+electrons of particular symmetry, which takes place in the buffer Fe-O layer,
+when on-site Coulomb repulsion is introduced. We further study the possible
+influence of the symmetry reduction in the buffer Fe-O layer on the transport
+properties of the Fe/MgO/Fe interface.",1212.1374v1
+2012-12-24,Competing Antiferromagnetic and Spin-Glass Phases in a Hollandite Structure,"We introduce a simple lattice model with Ising spins to explain recent
+experimental results on spin freezing in a hollandite-type structure. We argue
+that geometrical frustration of the lattice in combination with
+nearest-neighbour antiferromagnetic (AFM) interactions is responsible for the
+appearance of a spin-glass phase in presence of disorder. We investigate this
+system numerically using parallel tempering. The model reproduces the magnetic
+behaviour of oxides with hollandite structure, such as $\alpha-\text{MnO}_2$
+and presents a rich phenomenology: in absence of disorder three types of ground
+states are possible, depending on the relative strength of the interactions,
+namely AFM ordered and two different disordered, macroscopically degenerate
+families of ground states. Remarkably, for sets of AFM couplings having an AFM
+ground state in the clean system, there exists a critical value of the disorder
+for which the ground state is replaced by a spin-glass phase while maintaining
+all couplings AFM. To the best of our knowledge this is the only existing model
+that presents this kind of transition with short-range AFM interactions. We
+argue that this model could be useful to understand the relation between AFM
+coupling, disorder and the appearance of a spin-glass phase.",1212.5954v1
+2013-01-21,The origin of the dead-layer at the La0.67Sr0.33MnO3/SrTiO3 interface and dead-layer reduction via interfacial engineering,"Transition metal oxide hetero-structure has great potential for
+multifunctional devices. However, the degraded physical properties at
+interface, known as dead-layer behavior, present a main obstacle for device
+applications. Here we present the systematic study of the dead-layer behavior
+in La0.67Sr0.33MnO3 thin film grown on SrTiO3 substrate with ozone assisted
+molecular beam epitaxy. We found that the evolution of electric and magnetic
+properties as a function of thickness shows a remarkable resemblance to the
+phase diagram as a function of doping for bulk materials, providing compelling
+evidences of the hole depletion in near interface layers that causes
+dead-layer. Detailed electronic and surface structure studies indicate that the
+hole depletion is due to the intrinsic oxygen vacancy formation. Furthermore,
+we show that oxygen vacancies are partly caused by interfacial electric dipolar
+field, and thus by doping-engineering at the single-atomic-layer level, we
+demonstrate the dead-layer reduction in films with higher interfacial hole
+concentration.",1301.4822v1
+2013-01-24,"Superconductivity, Antiferromagnetism, and Neutron Scattering","High-temperature superconductivity in both the copper-oxide and the
+iron-pnictide/chalcogenide systems occurs in close proximity to
+antiferromagnetically ordered states. Neutron scattering has been an essential
+technique for characterizing the spin correlations in the antiferromagnetic
+phases and for demonstrating how the spin fluctuations persist in the
+superconductors. While the nature of the spin correlations in the
+superconductors remains controversial, the neutron scattering measurements of
+magnetic excitations over broad ranges of energy and momentum transfer provide
+important constraints on the theoretical options. We present an overview of the
+neutron scattering work on high-temperature superconductors and discuss some of
+the outstanding issues.",1301.5888v1
+2013-02-05,Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting,"Although silicon is a promising material for quantum computation, the
+degeneracy of the conduction band minima (valleys) must be lifted with a
+splitting sufficient to ensure formation of well-defined and long-lived spin
+qubits. Here we demonstrate that valley separation can be accurately tuned via
+electrostatic gate control in a metal-oxide-semiconductor quantum dot,
+providing splittings spanning 0.3 - 0.8 meV. The splitting varies linearly with
+applied electric field, with a ratio in agreement with atomistic tight-binding
+predictions. We demonstrate single-shot spin readout and measure the spin
+relaxation for different valley configurations and dot occupancies, finding
+one-electron lifetimes exceeding 2 seconds. Spin relaxation occurs via phonon
+emission due to spin-orbit coupling between the valley states, a process not
+previously anticipated for silicon quantum dots. An analytical theory describes
+the magnetic field dependence of the relaxation rate, including the presence of
+a dramatic rate enhancement (or hot-spot) when Zeeman and valley splittings
+coincide.",1302.0983v2
+2013-02-10,Single Dirac-Cone State and Quantum Hall Effects in Honeycomb Structure,"A honeycomb lattice system has four types of Dirac electrons corresponding to
+the spin and valley degrees of freedom. We consider a state that contains only
+one type of massless electrons and three types of massive ones, which we call
+the single Dirac-cone state. We analyze quantum Hall (QH) effects in this
+state. We make a detailed investigation of the Chern and spin-Chern numbers. We
+make clear the origin of unconventional QH effects discovered in graphene. We
+also show that the single Dirac-cone state may have arbitrary large spin-Chern
+numbers in magnetic field. Such a state will be generated in antiferromagnetic
+transition-metal oxides under electric field or silicene with antiferromagnetic
+order under electric field.",1302.2284v2
+2013-04-02,Ab initio study of the TiO$_2$ Rutile(110)/Fe interface,"Adsorption of Fe on the rutile (110)-surface is investigated by means of {\it
+ab initio} density functional theory calculations. We discuss the deposition of
+single Fe atoms, an increasing Fe coverage, as well as the adsorption of small
+Fe clusters. It is shown that the different interface structures found in
+experiment can be understood in terms of the adsorption of the Fe atoms landing
+first on the rutile surface. On the one hand, strong interface bonds form if
+single Fe atoms are deposited. On the other hand, the Fe-Fe bonds in deposited
+Fe clusters lead to a three-dimensional growth mode. Mainly ionic Fe-oxide
+bonds are formed in both cases and the electronic band gap of the surface is
+reduced due to interface states. Besides the structural and electronic
+properties, we discuss the influence of the interface on the magnetic
+properties finding stable Fe moments and induced moments within the interface
+which leads to a large spin polarization of the Fe atoms at the rutile (110)/Fe
+interface.",1304.0570v1
+2013-04-24,Spin Resolution and Evidence for Superexchange on NiO(001) observed by Force Microscopy,"The spin order of the nickel oxide (001) surface is resolved, employing
+non-contact atomic force microscopy at 4.4 K using bulk Fe- and SmCo-tips
+mounted on a qPlus sensor that oscillates at sub-50 pm amplitudes. The
+spin-dependent signal is hardly detectable with Fe-tips. In contrast, SmCo-tips
+yield a height contrast of 1.35 pm for Ni ions with opposite spins. SmCo tips
+even show a small height contrast on the O atoms of 0.5 pm within the 2x1 spin
+unit cell, pointing to the observation of superexchange. We attribute this to
+the increased magnetocrystalline anisotropy energy of SmCo, which stabilizes
+the magnetic moment at the apex. Atomic force spectroscopy on the Ni up, Ni
+down and O lattice site reveals a magnitude of the exchange energy of merely 1
+meV at the closest accessible distance with an exponential decay length of
+\lambda_exc = 18 pm.",1304.6515v3
+2013-04-29,Engineering Correlation Effects via Artificially Designed Oxide Superlattices,"Ab initio calculations are used to predict that a superlattice composed of
+layers of LaTiO3 and LaNiO3 alternating along the [001] direction is a S=1 Mott
+insulator with large magnetic moments on the Ni sites, negligible moments on
+the Ti sites and a charge transfer gap set by the energy difference between Ni
+d and Ti d states, distinct from conventional Mott insulators. Correlation
+effects are enhanced on the Ni sites via filling the oxygen p states and
+reducing the Ni-O-Ni bond angle. Small hole (electron) doping of the
+superlattice leads to a two-dimensional single-band situation with holes
+(electrons) residing on Ni dx2-y2 (Ti dxy) orbital and coupled to
+antiferromagnetically correlated spins in the NiO2 layer.",1304.7815v1
+2013-05-29,Thermal drag in spin ladders coupled to phonons,"We study the spin-phonon drag effect in the magnetothermal transport of
+spin-1/2 two-leg ladders coupled to lattice degrees of freedom. Using a bond
+operator description for the triplon excitations of the spin ladder and
+magnetoelastic coupling to acoustic phonons, we employ the time convolutionless
+projection operator method to derive expressions for the diagonal and
+off-diagonal thermal conductivities of the coupled two-component triplon-phonon
+system. We find that for magnetoelastic coupling strengths and diagonal
+scattering rates relevant to copper-oxide spin-ladders the drag heat
+conductivity can be of similar magnitude as the diagonal triplon heat
+conductivity. Moreover, we show that the drag and diagonal conductivities
+display very similar overall temperature dependences. Finally, the drag
+conductivity is shown to be rather susceptible to external magnetic fields.",1305.6911v1
+2013-06-09,Quantum nucleation of effective Minkowski spacetime in hyperbolic metamaterials based on high Tc superconductors,"We demonstrate that high Tc superconductors exhibit hyperbolic metamaterial
+behavior in the far infrared and THz frequency ranges. In the THz range the
+hyperbolic behavior occurs only in the normal state, while no propagating modes
+exist in the superconducting state. Wave equation, which describes propagation
+of extraordinary light inside a hyperbolic metamaterial exhibits 2+1
+dimensional Lorentz symmetry. The role of time in the corresponding effective
+3D Minkowski spacetime is played by the spatial coordinate aligned
+perpendicular to the copper oxide layers. Such superconductor-based hyperbolic
+metamaterials exhibit a quantum phase transition at T=0, in which the effective
+Minkowski spacetime arise in the mixed state of the superconductor at some
+critical value of external magnetic field. Nucleation of Minkowski spacetime
+occurs via formation of quantized Abrikosov vortices, so that these vortices
+play the role of effective Minkowski spacetime quanta.",1306.1975v2
+2013-07-02,Non-volatile ferroelastic switching of the Verwey transition and resistivity of epitaxial Fe3O4/PMN-PT (011),"A central goal of electronics based on correlated materials or 'Mottronics'
+is the ability to switch between distinct collective states with a control
+voltage. Small changes in structure and charge density near a transition can
+tip the balance between competing phases, leading to dramatic changes in
+electronic and magnetic properties. In this work, we demonstrate that an
+electric field induced two-step ferroelastic switching pathway in (011)
+oriented 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-PT) substrates can be used to
+tune the Verwey metal-insulator transition in epitaxial Fe3O4 films in a stable
+and reversible manner. We also observe robust non-volatile resistance switching
+in Fe3O4 up to room temperature, driven by ferroelastic strain. These results
+provides a framework for realizing non-volatile and reversible tuning of order
+parameters coupled to lattice-strain in epitaxial oxide heterostructures over a
+broad range of temperatures, with potential device applications.",1307.0838v1
+2013-07-17,Growth modes of nanoparticle superlattice thin films,"We report about the fabrication and characterization of iron oxide
+nanoparticle thin film superlattices. The formation into different film
+morphologies is controlled by tuning the particle plus solvent-to-substrate
+interaction. It turns out that the wetting vs. dewetting properties of the
+solvent before the self-assembly process during solvent evaporation plays a
+major role to determine the resulting film morphology. In addition to layerwise
+growth also three-dimensional mesocrystalline growth is evidenced. The
+understanding of the mechanisms ruling nanoparticle self-assembly represents an
+important step toward the fabrication of novel materials with tailored optical,
+magnetic or electrical transport properties.",1307.4693v4
+2013-11-05,Mixed valency and site-preference chemistry for Cerium and its compounds: A predictive DFT study,"Cerium and its technologically relevant compounds are examples of anomalous
+mixed valency, originating from two competing oxidation states -- itinerant
+Ce$^{3+}$ and localized Ce$^{4+}$. Under applied stress, anomalous transitions
+are observed but not well understood. Here we treat mixed valency as an ""alloy""
+involving two valences with competing and numerous site-occupancy
+configurations, and we use density functional theory with Hubbard U ($i.e.$,
+DFT+U) to evaluate the effective valence and predict properties, including
+controlling valence by pseudo-ternary alloying. For Ce and its compounds, such
+as (Ce-La)$_2$(Fe-Co)$_{14}$B permanent magnets, we find a stable mixed-valent
+$\alpha$-state near the spectroscopic value of $\nu_s=3.53$. Ce valency in
+compounds depends on its steric volume and local chemistry; for La doping,
+Ce-valency shifts towards $\gamma$-like Ce$^{3+}$, as expected from steric
+volume; for Co doping, valency depends on local Ce-site chemistry and steric
+volume. Our approach captures the key origins of anomalous valency and
+site-preference chemistry in complex compounds.",1311.0962v1
+2013-11-07,Imaging the Nanoscale Band Structure of Topological Sb,"Many promising building blocks of future electronic technology - including
+non-stoichiometric compounds, strongly correlated oxides, and strained or
+patterned films - are inhomogeneous on the nanometer length scale. Exploiting
+the inhomogeneity of such materials to design next-generation nanodevices
+requires a band structure probe with nanoscale spatial resolution. To address
+this demand, we report the first simultaneous observation and quantitative
+reconciliation of two candidate probes - Landau level spectroscopy and
+quasiparticle interference imaging - which we employ here to reconstruct the
+multi-component surface state band structure of the topological semimetal
+antimony(Sb). We thus establish the technique of band structure tunneling
+microscopy (BSTM), whose unique advantages include nanoscale access to
+non-rigid band structure deformation, empty state dispersion, and magnetic
+field dependent states. We use BSTM to elucidate the relationship between bulk
+conductivity and surface state robustness in topological materials, and to
+quantify essential metrics for spintronics applications.",1311.1758v1
+2013-11-13,A new route to spin-orbit torque engineering via oxygen manipulation,"Spin transfer torques allow for electrical manipulation of magnetization at
+room temperature, which is utilized to build future electronic devices such as
+spin transfer torque memories. Recent experiments have discovered that the
+combination of the spin transfer torque with the spin Hall effect enables more
+efficient manipulation. A versatile control mechanism of such spin-orbit
+torques is beneficial to envision device applications with competitive
+advantages over the existing schemes. Here we report that the oxidation
+manipulation of spin-orbit torque devices triggers a new mechanism, and the
+resulting torques are estimated to be about two times stronger than that of the
+spin Hall effect. Our result introduces an entirely new way to engineer the
+spin-orbit torques for device operation via oxygen manipulation. Combined with
+electrical gating for the control of the oxygen content, our finding may also
+pave the way for towards reconfigurable logic devices.",1311.3032v1
+2013-11-20,Electron Correlation in Oxygen Vacancy in SrTiO$_3$,"Oxygen vacancies are an important type of defect in transition metal oxides.
+In SrTiO$_3$ they are believed to be the main donors in an otherwise intrinsic
+crystal. At the same time, a relatively deep gap state associated with the
+vacancy is widely reported. To explain this inconsistency we investigate the
+effect of electron correlation in an oxygen vacancy (OV) in SrTiO$_3$. When
+taking correlation into account, we find that the OV-induced localized level
+can at most trap one electron, while the second electron occupies the
+conduction band. Our results offer a natural explanation of how the OV in
+SrTiO$_3$ can produce a deep in-gap level (about 1 eV below the conduction band
+bottom) in photoemission, and at the same time be an electron donor. Our
+analysis implies an OV in SrTiO$_3$ should be fundamentally regarded as a
+magnetic impurity, whose deep level is always partially occupied due to the
+strong Coulomb repulsion. An OV-based Anderson impurity model is derived, and
+its implications are discussed.",1311.5160v1
+2013-11-23,Thirty Femtograms Detection of Iron in Mammalian Cells,"Inorganic nanomaterials and particles with enhanced optical, mechanical or
+magnetic attributes are currently being developed for a wide range of
+applications. Safety issues have been formulated however concerning their
+potential cyto- and genotoxicity. For in vivo and in vitro experimentations,
+recent developments have heightened the need of simple and facile methods to
+measure the amount of nanoparticles taken up by cells or tissues. In this work,
+we present a rapid and highly sensitive method for quantifying the uptake of
+iron oxide nanoparticles in mammalian cells. Our approach exploits the
+digestion of incubated cells with concentrated hydrochloric acid reactant and a
+colorimetric based UV-Visible absorption technique. The technique allows the
+detection of iron in cells over 4 decades in masses, from 0.03 to 300 picograms
+per cell. Applied on particles of different surface chemistry and sizes, the
+protocol demonstrates that the coating is the key parameter in the
+nanoparticle/cell interactions. The data are corroborated by scanning and
+transmission electron microscopy and stress the importance of resiliently
+adsorbed nanoparticles at the plasma membrane.",1311.6019v1
+2013-12-05,p-Type Zinc Oxide Spinels: Application to Transparent Conductors and Spintronics,"We report on the electronic and optical properties of two theoretically
+predicted stable spinel compounds of the form ZnB2O4, where B = Ni or Cu;
+neither compound has been previously synthesized, so we compare them to the
+previously studied p-type ZnCo2O4 spinel. These new materials exhibit spin
+polarization that is ideal for spintronics applications, and broad conductivity
+maxima near the valence band edge that facilitate p-type dopability. We show
+that 3d electrons on the octahedrally coordinated Zn atom fall deep within the
+valence band and do not contribute significantly to the electronic structure of
+the material, while the O 2p and tetrahedrally coordinated B 3d electrons
+hybridize broadly in the shallow valence states, resulting in increasing
+curvature (i.e., decreased electron effective mass) of valence bands near the
+band edge. In particular, ZnCu2O4 exhibits high electrical conductivities near
+the valence band edge that, at sigma = 2 x 10^4 S/cm, are twice the maximum
+found for ZnCo2O4, a previously synthesized compound in this class of
+materials. This material also exhibits ferromagnetism in all of its most stable
+structures, which makes it a good candidate for further study as a dilute
+magnetic semiconductor.",1312.1728v1
+2014-02-05,First-Principles Study of the Honeycomb-Lattice Iridates Na2IrO3 in the Presence of Strong Spin-Orbit Interaction and Electron Correlations,"An effective low-energy Hamiltonian of itinerant electrons for iridium oxide
+Na2IrO3 is derived by an ab initio downfolding scheme. The model is then
+reduced to an effective spin model on a honeycomb lattice by the strong
+coupling expansion. Here we show that the ab initio model contains spin-spin
+anisotropic exchange terms in addition to the extensively studied Kitaev and
+Heisenberg exchange interactions, and allows to describe the experimentally
+observed zigzag magnetic order, interpreted as the state stabilized by the
+antiferromagnetic coupling of the ferromagnetic chains. We clarify possible
+routes to realize quantum spin liquids from existing Na2IrO3.",1402.1030v2
+2014-02-12,Refinement of Nb3Sn grain size by the generation of ZrO2 precipitates in Nb3Sn wires,"In this letter we demonstrate that if oxygen can be properly supplied to
+(Nb-Zr)-Sn wires, ZrO2 precipitates will form during the heat treatment,
+refining the Nb3Sn grain size markedly. Here, a Nb3Sn subelement was fabricated
+in which Nb-1Zr alloy was used, and oxygen was supplied via SnO2 powder. The
+results showed that such a design could supply sufficient oxygen to internally
+oxidize the Zr in the Nb-1Zr alloy, and that the sample reacted at 650 {\deg}C
+had grain sizes of ~45 nm, less than half the size of the grains in present
+Nb3Sn conductors. Magnetic measurements showed that the peak of the pinning
+force vs. field (Fp-B) curve was shifted to ~0.3Birr (the irreversibility
+field).",1402.3001v2
+2014-04-07,Structural insight into $Co_{3-x}Mn_xTeO_6$; ($0 \lt x \le 2$) solid solutions using Synchrotron X-ray diffraction and XANES,"Structural investigation on $Co_{3-x}Mn_xTeO_6$; ($0 \lt x \le 2$) solid
+solutions as a function of Mn concentration using Synchrotron X-ray diffraction
+(SXRD) and XANES measurements are presented. Phase diagram obtained from
+Rietveld Refinement on SXRD data as a function of Mn concentration indicates
+doping disproportionate mixing of both monoclinic (C2/c) and rhombohedral (R-3)
+structure (for $x \lt 0.5$) while only R-3 symmetry for $x \ge 0.5$.
+Furthermore, Rietveld analysis on SXRD data shows increase in lattice
+parameters and average transition metal oxygen (Co/Mn-O) bond lengths for $x
+\ge 0.5$. Co and Mn K-edge XANES spectra reveal that both Co and Mn are in
+mixed oxidation state of $Co^{2+}/Mn^{2+}$ and $Co^{3+}/Mn^{3+}$. Relative
+ratio of $Co^{3+}/Co^{2+}$ and $Mn^{3+}/Mn^{2+}$ using Linear combination fit
+(LCF) decrease with increasing $x$ for $x \ge 0.5$. These structural and
+spectroscopic evidences are used to provide possible interpretation of the
+reported observations of maximum Neel Temperature (TN) at $x ~\sim 0.5$ and
+enhancements of antiferro/ferro-magnetic interactions in $Co_{3-x}Mn_xTeO_6$
+solid solutions.",1404.1666v1
+2014-06-12,Tube filling technique influence on superconductivity in MgB2-based conductors prepared using laboratory made boron,"Here we report a systematic study of superconductive properties of
+mono-filamentary MgB2-based wires, manufactured with different filling
+technique. A detailed comparison of the influence of filling technique and
+final heat treatment on superconducting properties has been given. Boron used
+was synthesized in laboratory following magnesiothermic reduction of boron
+oxide, purified thanks to several acid leaching and heat treated at high
+temperature, to enhance crystalline degree. Critical current density and
+critical temperature have been investigated at different synthesis/sintering
+temperature in order to evaluate their dependence to applied final heat
+treatment. Critical current density has been evaluated on short wire pieces by
+magnetic measurement in a MPMS 5.5T Quantum Design SQUID, while critical
+temperature has been measured with a four probe system, by the drop of
+resistivity during the cooling of the sample in a liquid helium dewar.",1407.2111v1
+2014-07-24,Extraordinary Tunability of the Superexchange Interactions in Nanoparticles of the Multiferroic 0.50BiFeO3-0.50PbTiO3,"The coexistence and coupling of magnetic and ferroelectric orderings in
+single phase multiferroics has evinced enormous scientific interest as it
+involves breaking of time reversal and space inversion symmetries in the same
+material. The mutual controllability of the two diverse orderings in
+multiferroics has potential for developing new generation multifunctional
+sensor, actuator and data storage devices. We present here evidence for a new
+exotic facet of multiferroicity, whereby one can raise the strength of
+antiferromagnetic (AFM) superexchange interaction and hence tune the N\'eel
+temperature (TN) from ~120K in bulk to ~350K in 18nm size particles by tuning
+the ferroelectric distortion in the tetragonal phase of multiferroic
+(1-x)BiFeO3 -xPbTiO3 solid solutions . This observation is unique to
+multiferroics only as the TN in non-multiferroic AFM oxides decreases with
+particle size. Our results provide a scientific basis for designing room
+temperature single phase multiferroics, useful for making multifunctional
+device operating at room temperature.",1407.6485v1
+2014-09-30,"Coupling and Electrical Control of Structural, Orbital and Magnetic Orders in Perovskites","Perovskite oxides are already widely used in industry and have huge potential
+for novel device applications thanks to the rich physical behaviour displayed
+in these materials. The key to the functional electronic properties exhibited
+by perovskites is often the so-called Jahn-Teller distortion. For applications,
+an electrical control of the Jahn-Teller distortions, which is so far out of
+reach, would therefore be highly desirable. Based on universal symmetry
+arguments, we determine new lattice mode couplings that can provide exactly
+this paradigm, and exemplify the effect from first-principles calculations. The
+proposed mechanism is completely general, however for illustrative purposes, we
+demonstrate the concept on vanadium based perovskites where we reveal an
+unprecedented orbital ordering and Jahn-Teller induced ferroelectricity. Thanks
+to the intimate coupling between Jahn-Teller distortions and electronic degrees
+of freedom, the electric field control of Jahn-Teller distortions is of general
+relevance and may find broad interest in various functional devices.",1409.8422v1
+2014-10-07,Decoding Spatial Complexity in Strongly Correlated Electronic Systems,"Inside the metals, semiconductors, and magnets of our everyday experience,
+electrons are uniformly distributed throughout the material. By contrast,
+electrons often form clumpy patterns inside of strongly correlated electronic
+systems (SCES) such as colossal magnetoresistance materials and high
+temperature superconductors. In copper-oxide based high temperature
+superconductors, scanning tunneling microscopy (STM) has detected an electron
+nematic on the surface of the material, in which the electrons form nanoscale
+structures which break the rotational symmetry of the host crystal. These
+structures may hold the key to unlocking the mystery of high temperature
+superconductivity in these materials, but only if the nematic also exists
+throughout the entire bulk of the material. Using newly developed methods for
+decoding these surface structures, we find that the nematic indeed persists
+throughout the bulk of the material. We furthermore find that the intricate
+pattern formation is set by a delicate balance among disorder, interactions,
+and material anisotropy, leading to a fractal nature of the cluster pattern.
+The methods we have developed can be extended to many other surface probes and
+materials, enabling surface probes to determine whether surface structures are
+confined only to the surface, or whether they extend throughout the material.",1410.1787v1
+2014-11-06,Facetted growth of Fe3Si shells around GaAs nanowires on Si(111),"GaAs nanowires and GaAs/Fe3Si core/shell nanowire structures were grown by
+molecular-beam epitaxy on oxidized Si(111) substrates and characterized by
+transmission electron microscopy. The surfaces of the original GaAs NWs are
+completely covered by magnetic Fe3Si exhibiting nanofacets and an enhanced
+surface roughness compared to the bare GaAs NWs. Shell growth at a substrate
+temperature of T{S} = 200 {\deg}C leads to regular nanofacetted Fe3Si shells.
+These facets, which lead to thickness inhomogeneities of the shells, consist
+mainly of well pronounced Fe3Si(111) planes. The crystallographic orientation
+of core and shell coincide, i.e. they are pseudomorphic. The nanofacetted Fe3Si
+shells found in the present work are probably the result of the Vollmer-Weber
+island growth mode of Fe3Si on the {110} side facets of the GaAs NWs.",1411.1556v2
+2014-11-07,Numerical evidence of quantum melting of spin ice: quantum-classical crossover,"Unbiased quantum Monte-Carlo simulations are performed on the
+nearest-neighbor spin-$\frac{1}{2}$ pyrochlore XXZ model with an
+antiferromagnetic longitudinal and a weak ferromagnetic transverse exchange
+couplings, $J$ and $J_\perp$. The specific heat exhibits a broad peak at
+$T_{\mathrm{CSI}}\sim0.2J$ associated with a crossover to a classical Coulomb
+liquid regime showing a suppressed spin-ice monopole density, a broadened
+pinch-point singularity, and the Pauling entropy for $|J_\perp|\ll J$, as in
+classical spin ice. On further cooling, the entropy restarts decaying for
+$J_\perp>J_{\perp c}\sim-0.104J$, producing another broad specific heat peak
+for a crossover to a bosonic quantum Coulomb liquid, where the spin correlation
+contains both photon and quantum spin-ice monopole contributions. With
+negatively increasing $J_\perp$ across $J_{\perp c}$, a first-order thermal
+phase transition occurs from the quantum Coulomb liquid to an XY ferromagnet.
+Relevance to magnetic rare-earth pyrochlore oxides is discussed.",1411.1918v3
+2015-01-21,Large exchange bias in polycrystalline MnN/CoFe bilayers at room temperature,"We report on the new polycrystalline exchange bias system MnN/CoFe, which
+shows exchange bias of up to 1800Oe at room temperature with a coercive field
+around 600Oe. The room temperature values of the interfacial exchange energy
+and the effective uniaxial anisotropy are estimated to be $J_\mathrm{eff} =
+0.41\,\mathrm{mJ}/\mathrm{m}^2$ and $K_\mathrm{eff} =
+37\,\mathrm{kJ}\,/\,\mathrm{m}^3$. The thermal stability was found to be
+tunable by controlling the nitrogen content of the MnN. The maximum blocking
+temperature exceeds $325^\circ$C, however the median blocking temperature in
+the limit of thick MnN is $160^\circ$C. Good oxidation stability through
+self-passivation was observed, enabling the use of MnN in lithographically
+defined microstructures. As a proof-of-principle we demonstrate a simple GMR
+stack exchange biased with MnN, which shows clear separation between parallel
+and antiparallel magnetic states. These properties come along with a
+surprisingly simple manufacturing process for the MnN films.",1501.05162v2
+2015-02-24,"Electro-mechanical properties of REBCO coated conductors from various industrial manufacturers at 77 K, self-field and 4.2 K, 19 T","Rare-earth-barium-copper-oxide (REBCO) tapes are now available from several
+industrial manufacturers and are very promising conductors in high field
+applications. Due to diverging materials and deposition processes, these
+manufacturers' tapes can be expected to differ in their electro-mechanical and
+mechanical properties. For magnets designers, these are together with the
+conductors' in-field critical current performance of the highest importance in
+choosing a suitable conductor. In this work, the strain and stress dependence
+of the current carrying capabilities as well as the stress and strain
+correlation are investigated for commercial coated conductors from Bruker HTS,
+Fujikura, SuNAM, SuperOx and SuperPower at 77 K, self-field and 4.2 K, 19 T.",1502.06713v1
+2015-02-24,High Quality Yttrium Iron Garnet Grown by Room Temperature Pulsed Laser Deposition and Subsequent Annealing,"We have investigated recrystallization of amorphous Yttrium Iron Garnet (YIG)
+by annealing in oxygen atmosphere. Our findings show that well below the
+melting temperature the material transforms into a fully epitaxial layer with
+exceptional quality, both structural and magnetic.\\ In ferromagnetic resonance
+(FMR) ultra low damping and extremely narrow linewidth can be observed. For a
+56 nm thick layer a damping constant of
+$\alpha$=(6.63$\pm$1.50)$\cdot$10$^{-5}$ is found and the linewidth at 9.6 GHz
+is as small as 1.30$\pm$0.05 Oe which are the lowest values for PLD grown thin
+films reported so far. Even for a 20 nm thick layer a damping constant of
+$\alpha$=(7.51$\pm$1.40)$\cdot$10$^{-5}$ is found which is the lowest value for
+ultrathin films published so far. The FMR linewidth in this case is
+3.49$\pm$0.10 Oe at 9.6 GHz. Our results not only present a method of
+depositing thin film YIG of unprecedented quality but also open up new options
+for the fabrication of thin film complex oxides or even other crystalline
+materials.",1502.06724v2
+2015-02-26,Inhomogeneous multi-carrier superconductivity at LaXO3/SrTiO3 (X=Al or Ti) oxide interfaces,"Several experiments reveal the inhomogeneous character of the superconducting
+state that occurs when the carrier density of the two-dimensional electron gas
+formed at the LaXO3/SrTiO3 (X=Al or Ti) interface is tuned above a threshold
+value by means of gating. Re-analyzing previous measurements, that highlight
+the presence of two kinds of carriers, with low and high mobility, we shall
+provide a description of multi-carrier magneto-transport in an inhomogeneous
+two-dimensional electron gas, gaining insight into the properties of the
+physics of the systems under investigation. We shall then show that the
+measured resistance, superfluid density, and tunneling spectra result from the
+percolative connection of superconducting ""puddles"" with randomly distributed
+critical temperatures, embedded in a weakly localizing metallic matrix. We
+shall also show that this scenario is consistent with the characteristics of
+the superconductor-to-metal transition driven by a magnetic field. A
+multi-carrier description of the superconducting state, within a weak-coupling
+BCS-like model, will be finally discussed.",1502.07572v1
+2015-04-06,Probing the electron-phonon interaction in correlated systems with coherent lattice fluctuation spectroscopy,"Tailoring the properties of correlated oxides is accomplished by chemical
+doping, pressure, temperature or magnetic field. Photoexcitation is a valid
+alternative to reach out-of-equilibrium states otherwise inaccessible. Here, we
+quantitatively estimate the coupling between a lattice distortion and the
+charge-transfer excitation in (La$_2$CuO$_{4+\delta}$). We photoinduce a
+coherent La ion vibration and monitor the response of the optical constants in
+a broad energy range, providing quantitative information on the electron-phonon
+matrix element that can be compared to theoretical models. We propose the same
+methodology to probe electron-electron interactions in other materials.",1504.02760v1
+2015-07-06,Quantum Oscillations in Hole-Doped Cuprates,"One of the leading challenges of condensed matter physics in the past few
+decades in an understanding of the high-temperature copper-oxide
+superconductors. While the d-wave character of the superconducting state is
+well understood, the normal state in the underdoped regime has eluded
+understanding. Here we review the past few years of quantum oscillation
+measurements performed in the underdoped cuprates that have culminated in an
+understanding of the normal ground state of these materials. A nodal electron
+pocket created by charge order is found to characterise the normal ground state
+in YBa2Cu3O6+x and is likely universal to a majority of the cuprate
+superconductors. An open question remains regarding the origin of the
+suppression of the antinodal density of states at the Fermi energy in the
+underdoped normal state, either from mainly charge correlations, or more
+likely, from mainly pairing and / or magnetic correlations that precede charge
+order.",1507.01315v1
+2015-07-07,Chemical modification of silicene,"Silicene is a two-dimensional material, which is composed of a single layer
+of silicon atoms with sp2-sp3 mixed hybridization. The sp2-sp3 mixed
+hybridization renders silicene excellent reactive ability, facilitating the
+chemical modification of silicene. It has been demonstrated that chemical
+modification effectively enables the tuning of the properties of silicene. We
+now review all kind of chemical modification methods for silicene including
+hydrogenation, halogenation, organic surface modification, oxidation, doping
+and alloying. The effects of these chemical modification methods on the
+geometrical, electronic, optical and magnetic properties of silicene are
+discussed. The potential applications of chemically modified silicene in a
+variety of fields such as electronics, optoelectronics and magnetoelectronics
+are introduced. We finally envision future work on the chemical modification of
+silicene for the sake of further advancing the development of silicene.",1507.01658v1
+2015-07-09,Casimir and van der Waals forces: Advances and problems,"We review modern achievements and problems in physics of the van der Waals
+and Casimir forces which arise due to zero-point and thermal fluctuations of
+the electromagnetic field between closely spaced material surfaces. This
+subject attracted great experimental and theoretical attention during the last
+few years because the fluctuation-induced forces find a lot of applications in
+both fundamental physics and nanotechnology. After a short introduction to the
+subject, we describe main experimental and theoretical results obtained in the
+field during the last fifteen years. In the following presentation, we discuss
+some of the recent results by the authors and their collaborators which are of
+high promise for future developments. Specifically, we consider new features of
+the Casimir force acting between a gold sphere and an indium tin oxide plate,
+present the experimental and theoretical results on measuring the Casimir
+interaction between two gold surfaces by means of dynamic atomic force
+microscope, and outline first measurements of the Casimir interaction between
+magnetic surfaces and related theory. Special attention is devoted to the
+Casimir effect for graphene, which is the prospective material for
+microelectromechanical devices of next generations.",1507.02393v1
+2015-08-01,Exchange-driven spin relaxation in ferromagnet/oxide/semiconductor heterostructures,"We investigate electron spin relaxation in GaAs in the proximity of a Fe/MgO
+layer using spin-resolved optical pump-probe spectroscopy, revealing a strong
+dependence of the spin relaxation time on the strength of an exchange-driven
+hyperfine field. The temperature dependence of this effect reveals a strong
+correlation with carrier freeze out, implying that at low temperatures the free
+carrier spin lifetime is dominated by inhomogeneity in the local hyperfine
+field due to carrier localization. This result resolves a long-standing and
+contentious question of the origin of the spin relaxation in GaAs at low
+temperature when a magnetic field is present. Further, this improved
+fundamental understanding paves the way for future experiments exploring the
+time-dependent exchange interaction at the ferromagnet/semiconductor interface
+and its impact on spin dissipation and transport in the regime of
+dynamically-driven spin pumping.",1508.00164v1
+2015-08-03,Theory of Valence Transition in BiNiO$_3$,"Motivated by the colossal negative thermal expansion recently found in
+BiNiO$_3$, the valence transition accompanied by the charge transfer between
+the Bi and Ni sites is theoretically studied. We introduce an effective model
+for Bi-$6s$ and Ni-$3d$ orbitals with taking into account the valence skipping
+of Bi cations, and investigate the ground-state and finite-temperature phase
+diagrams within the mean-field approximation. We find that the valence
+transition is caused by commensurate locking of the electron filling in each
+orbital associated with charge and magnetic orderings, and the critical
+temperature and the nature of the transitions are strongly affected by the
+relative energy between the Bi and Ni levels and the effective
+electron-electron interaction in the Bi sites. The obtained phase diagram well
+explains the temperature- and pressure-driven valence transitions in BiNiO$_3$
+and the systematic variation of valence states for a series of Bi and Pb
+perovskite oxides.",1508.00296v1
+2015-10-09,Better Band Gaps with Asymptotically Corrected Local Exchange Potentials,"We formulate a spin-polarized van Leeuwen and Baerends (vLB) correction to
+the local density approximation (LDA) exchange potential [Phys. Rev. A 49, 2421
+(1994)] that enforces the ionization potential (IP) theorem following Stein et
+al. [Phys. Rev. Lett. 105, 266802 (2010)]. For electronic-structure problems,
+the vLB-correction replicates the behavior of exact-exchange potentials, with
+improved scaling and well-behaved asymptotics, but with the computational cost
+of semi-local functionals. The vLB+IP corrections produces large improvement in
+the eigenvalues over that from LDA due to correct asympotic behavior and atomic
+shell structures, as shown on rare-gas, alkaline-earth, zinc-based oxides,
+alkali-halides, sulphides, and nitrides. In half-Heusler alloys, this
+asymptotically-corrected LDA reproduces the spin-polarized properties
+correctly, including magnetism and half-metallicity. We also considered
+finite-sized systems [e.g., ringed boron-nitirde (B$_{12}$N$_{12}$) and
+graphene (C$_{24}$)] to emphasize the wide applicability of the method.",1510.02688v3
+2015-10-26,Spin-dependent transport properties of a GaMnAs-based vertical spin metal-oxide- semiconductor field-effect transistor structure,"We fabricate a vertical spin metal-oxide-semiconductor field-effect
+transistor (spin-MOSFET) structure, which is composed of an epitaxial
+single-crystal heterostructure with a ferromagnetic-semiconductor GaMnAs
+source/drain, and investigate its spin-dependent transport properties. We
+modulate the drain-source current IDS by ~+ or -0.5 % with a gate-source
+voltage of + or -10.8 V and also modulate IDS by up to 60 % with changing the
+magnetization configuration of the GaMnAs source/drain at 3.5 K. The
+magnetoresistance ratio is more than two orders of magnitude higher than that
+obtained in the previous studies on spin MOSFETs. Our result shows that a
+vertical structure is one of the hopeful candidates for spin MOSFET when the
+device size is reduced to a sub-micron or nanometer scale.",1510.07497v1
+2015-10-31,Controlled formation of high-mobility shallow electron gases in SrTiO3 single crystal,"We report controlled formation of sub-100 nm-thin electron channels in
+SrTiO$_3$ by doping with oxygen vacancies induced by Ar$^+$-ion irradiation.
+The conducting channels exhibit a consistent high electron mobility (~15,000
+cm$^2$V$^{-1}$s$^{-1}$), which enables clear observation of magnetic quantum
+oscillations, and gate-tunable linear magnetoresistance. Near the onset of
+electrical conduction, the metal-insulator transition is induced by the
+mobility suppression. With the high electron mobility and the ease of
+controlled channel formation, this ion-irradiation doping method may provide an
+excellent basis for developing oxide electronics.",1511.00093v1
+2015-11-22,Passively Q-switched EDFL using Fe3O4-nanoparticle saturable absorber,"We experimentally demonstrate a passively Q-switched erbium-doped fiber laser
+(EDFL) operation by using a saturable absorber based on Fe3O4 nanoparticles
+(FONP) in magnetic fluid (MF). As a kind of transition metal oxide, the FONP
+has a large nonlinear optical response with a fast response time for saturable
+absorber. By depositing MF at the end of optical fiber ferrule, we fabricated a
+FONP-based saturable absorber, which enables a strong light-matter interaction
+owing to the confined transmitted optical field within the single mode fiber.
+Because of large third-order optical nonlinearities of FONP-based saturable
+absorber, large modulation depth of 8.2% and non saturable absorption of 56.6%
+are demonstrated. As a result, stable passively Q-switched EDFL pulses with
+maximum output pulse energy of 23.76 nJ, repetition rate of 33.3 kHz, and pulse
+width of 3.2 {\mu}s are achieved when the input pump power is 110 mW at the
+wavelength of 980 nm. The laser features a low threshold pump power of ~15 mW.",1511.07016v1
+2015-11-23,Direct probing of the Mott crossover in the SU($N$) Fermi-Hubbard model,"The Fermi-Hubbard model (FHM) is a cornerstone of modern condensed matter
+theory. Developed for interacting electrons in solids, which typically exhibit
+SU($2$) symmetry, it describes a wide range of phenomena, such as metal to
+insulator transitions and magnetic order. Its generalized SU($N$)-symmetric
+form, originally applied to multi-orbital materials such as transition-metal
+oxides, has recently attracted much interest owing to the availability of
+ultracold SU($N$)-symmetric atomic gases. Here we report on a detailed
+experimental investigation of the SU($N$)-symmetric FHM using local probing of
+an atomic gas of ytterbium in an optical lattice to determine the equation of
+state through different interaction regimes. We prepare a low-temperature
+SU($N$)-symmetric Mott insulator and characterize the Mott crossover,
+representing important steps towards probing predicted novel SU($N$)-magnetic
+phases.",1511.07287v1
+2016-03-03,Unconventional electron states in $δ$-doped SmTiO$_3$,"The Mott-insulating distorted perovskite SmTiO$_3$, doped with a single SrO
+layer in a quantum-well architecture is studied by the combination of density
+functional theory with dynamical mean-field theory. A rich correlated
+electronic structure in line with recent experimental investigations is
+revealed by the given realistic many-body approach to a large-unit-cell oxide
+heterostructure. Coexistence of conducting and Mott-insulating TiO$_2$ layers
+prone to magnetic order gives rise to multi-orbital electronic transport beyond
+standard Fermi-liquid theory. First hints towards a pseudogap opening due to
+electron-electron scattering within a background of ferromagnetic and
+antiferromagnetic fluctuations are detected.",1603.01031v4
+2016-03-10,Engineering charge ordering into multiferroicity,"Multiferroic materials have attracted great interests but are rare in nature.
+In many transitional metal oxides, charge ordering and magnetic ordering
+coexist, so that a method of engineering charge-ordered materials into
+ferroelectric materials would lead to a large class of multiferroic materials.
+We propose a strategy for designing new ferroelectric or even multiferroic
+materials by inserting a spacing layer into each two layers of charge-ordered
+materials and artificially making a superlattice. One example of the model
+demonstrated here is the perovskite (LaFeO$_3$)$_2$/LaTiO$_3$ (111)
+superlattice, in which the LaTiO$_3$ layer acts as the donor and the spacing
+layer, and the LaFeO$_3$ layer is half doped and performs charge ordering. The
+collaboration of the charge ordering and the spacing layer breaks the space
+inversion symmetry, resulting in a large ferroelectric polarization. As the
+charge ordering also leads to a ferrimagnetic structure, the
+(LaFeO$_3$)$_2$/LaTiO$_3$ is multiferroic. It is expected that this work can
+encourage the designing and experimentally implementation of a large class of
+multiferroic structures with novel properties.",1603.03253v1
+2016-03-30,Quantum Monte Carlo analysis of a charge ordered insulating antiferromagnet: the Ti$_4$O$_7$ Magnéli phase,"The Magn\'eli phase Ti$_4$O$_7$ is an important transition metal oxide with a
+wide range of applications because of its interplay between charge, spin, and
+lattice degrees of freedom. At low temperatures, it has non-trivial magnetic
+states very close in energy, driven by electronic exchange and correlation
+interactions. We have examined three low-lying states, one ferromagnetic and
+two antiferromagnetic, and calculated their energies as well as Ti spin moment
+distributions using highly accurate Quantum Monte Carlo methods. We compare our
+results to those obtained from density functional theory-based methods that
+include approximate corrections for exchange and correlation. Our results
+confirm the nature of the states and their ordering in energy, as compared with
+density-functional theory methods. However, the energy differences and spin
+distributions differ. A detailed analysis suggests that non-local
+exchange-correlation functionals, in addition to other approximations such as
+LDA+U to account for correlations, are needed to simultaneously obtain better
+estimates for spin moments, distributions, energy differences and energy gaps.",1603.09367v2
+2016-04-25,Quantitative determination of bond order and lattice distortions in nickel oxide heterostructures by resonant x-ray scattering,"We present a combined study of Ni $K$-edge resonant x-ray scattering and
+density functional calculations to probe and distinguish electronically driven
+ordering and lattice distortions in nickelate heterostructures. We demonstrate
+that due to the low crystal symmetry, contributions from structural distortions
+can contribute significantly to the energy-dependent Bragg peak intensities of
+a bond-ordered NdNiO$_3$ reference film. For a LaNiO$_3$-LaAlO$_3$ superlattice
+that exhibits magnetic order, we establish a rigorous upper bound on the
+bond-order parameter. We thus conclusively confirm predictions of a dominant
+spin density wave order parameter in metallic nickelates with a
+quasi-two-dimensional electronic structure.",1604.07317v1
+2016-06-06,New perspectives in the ultrafast spectroscopy of many-body excitations in correlated materials,"Ultrafast spectroscopies constitute a fundamental tool to investigate the
+dynamics of non-equilibrium many-body states in correlated materials.
+Two-pulses (pump-probe) experiments have shed new light on the interplay
+between high-energy electronic excitations and the emerging low-energy
+properties, such as superconductivity and charge-order, in many interesting
+materials. Here we will review some recent results on copper oxides and we will
+propose the use of high-resolution multi-dimensional techniques to investigate
+the decoherence processes of optical excitations in these systems. This novel
+piece of information is expected to open a new route toward the understanding
+of the fundamental interactions that lead to the exotic electronic and magnetic
+properties of correlated materials.",1606.01702v1
+2016-06-21,Instability of insulators near quantum phase transitions,"Thin films of Amorphous indium oxide undergo a magnetic field driven
+superconducting to insulator quantum phase transition. In the insulating phase,
+the current-voltage characteristics show large current discontinuities due to
+overheating of electrons. We show that the onset voltage for the
+discontinuities vanishes as we approach the quantum critical point.
+  As a result the insulating phase becomes unstable with respect to any applied
+voltage making it, at least experimentally, immeasurable.
+  We emphasize that unlike previous reports of the absence of linear response
+near quantum phase transitions, in our system, the departure from equilibrium
+is discontinuous. Because the conditions for these discontinuities are
+satisfied in most insulators at low temperatures, and due to the decay of all
+characteristic energy scales near quantum phase transitions, we believe that
+this instability is general and should occur in various systems while
+approaching their quantum critical point. Accounting for this instability is
+crucial for determining the critical behavior of systems near the transition.",1606.06606v2
+2016-06-24,Spin glass state and enhanced spiral phase in doped delafossite oxide CuCrO2,"In this work, we study the doping effects on the magnetic states of CuCrO2
+based on the classical frustrated spin model [Lin et al., Phys. Rev. B 89,
+220405(R) (2014)]. Several experimental observations can be well reproduced by
+the Monte Carlo simulations of the modified spin models. Our work suggests that
+the disorder induced by V/Al doping cooperated with the frustration in the
+system may contribute to the emergence of the spin glass state. Furthermore,
+the hole-doping by Mg2+ substituting Cr3+ enhances the quantum fluctuations and
+bond disorder which modulate the biquadratic exchanges, and in turn results in
+the promotion of the spiral phase, consistent with the experimental report.",1606.07854v1
+2016-06-29,Physics of ultrathin films and heterostructures of rare earth nickelates,"The electronic structure of transition metal oxides featuring correlated
+electrons can be rationalized within the Zaanen-Sawatzky-Allen framework.
+Following a brief description of the present paradigms of electronic behavior,
+we focus on the physics of rare earth nickelates as an archetype of complexity
+emerging within the charge transfer regime. The intriguing prospect of
+realizing the physics of high $T_c$ cuprates through heterostructuring resulted
+in a massive endeavor to epitaxially stabilize these materials in ultra-thin
+form. A plethora of new phenomena unfolded in such artificial structures due to
+the effect of epitaxial strain, quantum confinement, and interfacial charge
+transfer. Here we review the present status of artificial rare-earth nickelates
+in an effort to uncover the interconnection between the electronic and magnetic
+behavior and the underlying crystal structure. We conclude by discussing future
+directions to disentangle the puzzle regarding the origin of the
+metal-insulator transition, the role of oxygen holes, and the true nature of
+the antiferromagnetic spin configuration in the ultra-thin limit.",1606.09291v1
+2016-07-05,Effects of intense optical phonon pumping on the structure and electronic properties of yttrium barium copper oxide,"We investigate the structural modulations induced by optical excitation of a
+polar phonon mode in YBa$_2$Cu$_3$O$_7$, using first-principles calculations
+based on density functional theory. We focus on the intense-excitation regime
+in which we expect that fourth-order phonon-phonon coupling terms dominate, and
+model the structural modulations induced by pulses of such intensity. Our
+calculations of the phonon-phonon anharmonicities confirm that the cubic
+coupling between modes, shown in earlier work to cause a quasi-static change in
+the apical O - Cu distance and a buckling of the CuO$_2$ planes, is the leading
+contribution at moderate pump strengths. At higher pump strengths ($\sim$10
+MV/cm) the previously neglected quartic couplings become relevant and produce
+an additional shearing of the CuO$_2$ planes. Finally, we analyze the changes
+in the electronic and magnetic properties associated with the induced
+structural changes.",1607.01180v2
+2016-09-21,Universal self-field critical current for thin-film superconductors,"For any practical superconductor the magnitude of the critical current
+density, $J_\textrm{c}$, is crucially important. It sets the upper limit for
+current in the conductor. Usually $J_\textrm{c}$ falls rapidly with increasing
+external magnetic field but even in zero external field the current flowing in
+the conductor generates a self-field which limits $J_\textrm{c}$. Here we show
+for thin films of thickness less than the London penetration depth, $\lambda$,
+this limiting $J_\textrm{c}$ adopts a universal value for all superconductors -
+metals, oxides, cuprates, pnictides, borocarbides and heavy Fermions. For type
+I superconductors, it is $H_{\textrm{c}}/\lambda$ where $H_\textrm{c}$ is the
+thermodynamic critical field. But surprisingly for type II superconductors we
+find the self-field $J_\textrm{c}$ is $H_{\textrm{c}1}/\lambda$ where
+$H_{\textrm{c}1}$ is the lower critical field. $J_\textrm{c}$ is thus
+fundamentally determined and this provides a simple means to extract absolute
+values of $\lambda(T)$ and, from its temperature dependence, the symmetry and
+magnitude of the superconducting gap.",1609.06397v1
+2016-09-22,Quantum-Many-Body Intermetallics: Phase Stability of Fe$_3$Al and Small-Gap Formation in Fe$_2$VAl,"Various intermetallic compounds harbor subtle electronic correlation effects.
+To elucidate this fact for the Fe-Al system, we perform a realistic many-body
+investigation based on the combination of density functional theory with
+dynamical mean-field theory in a charge self-consistent manner. A better
+characterization and understanding of the phase stability of bcc-based
+D0$_3$-Fe$_3$Al through an improved description of the correlated charge
+density and the magnetic-energy is achevied. Upon replacement of one Fe
+sublattice by V, the Heusler compound Fe$_2$VAl is realized, known to display
+bad-metal behavior and increased specific heat. We here document a charge-gap
+opening at low temperatures in line with previous experimental work. The gap
+structure does not match conventional band theory and is reminiscent of
+(pseudo)gap charateristics in correlated oxides.",1609.06928v2
+2016-10-17,Observation of semi-localized dispersive states in the strongly correlated electron-doped ferromagnet Eu$_{1-x}$Gd$_{x}$O,"Chemical substitution plays a key role in controlling the electronic and
+magnetic properties of complex materials. For instance, in EuO, carrier doping
+can induce a spin-polarized metallic state, colossal magnetoresistance, and
+significantly enhance the Curie temperature. Here, we employ a combination of
+molecular-beam epitaxy, angle-resolved photoemission spectroscopy, and an
+effective model calculation to investigate and understand how semi-localized
+states evolve in lightly electron doped Eu$_{1-x}$Gd$_{x}$O above the
+ferromagnetic Curie temperature. Our studies reveal a characteristic length
+scale for the spatial extent of the donor wavefunctions which remains constant
+as a function of doping, consistent with recent tunneling studies of doped EuO.
+Our work sheds light on the nature of the semiconductor-to-metal transition in
+Eu$_{1-x}$Gd$_{x}$O and should be generally applicable for doped complex
+oxides.",1610.05337v1
+2016-10-19,Applications and non-idealities of submicron Al-AlOx-Nb tunnel junctions,"We have developed a technique to fabricate sub-micron, 0.6 um x 0.6 um
+Al-AlOx-Nb tunnel junctions using a standard e-beam resist, angle evaporation
+and double oxidation of the tunneling barrier, resulting in high quality
+niobium, as determined by the the high measured values of the critical
+temperature TC 7.5 K and the gap 1.3 meV. The devices show great promise for
+local nanoscale thermometry in the temperature range 1 - 7.5 K. Electrical
+characterization of the junctions was performed at sub-Kelvin temperatures both
+with and without an external magnetic field, which was used to suppress
+superconductivity in Al and thus bring the junction into a
+normal-metal-insulator-superconductor (NIS) configuration. We observed excess
+sub-gap current, which could not be explained by the standard tunneling theory.
+Evidence points towards materials science issues of the barrier or Nb/AlOx
+interface as the culprit.",1610.05903v1
+2017-02-09,Spin Transfer Torque Driven Coupled Oscillators for Self-Oscillating RF Mixers,"Spin transfer torque oscillators (STOs) based on magnetic tunnel junction
+(MTJ) devices are emerging as a possible replacement for complementary
+metal-oxide semiconductors for radio-frequency (RF) signal generation.
+Advantages include low power consumption, small device area, and large
+frequency tunability. But such a single device cannot achieve the necessary
+noise performance for RF applications. It has been reported lately that a
+network of globally coupled STOs achieves significant improvement in phase
+noise. The study here is to propose use of such coupled STOs as
+self-oscillating RF mixers. Critical mixer performance parameters, including
+conversion gain, output power, and linearity, are discussed.",1702.02746v5
+2017-02-14,Inelastic Light Scattering Spectroscopy of Magnons and Phonons in Nickel Oxide: Effects of Temperature,"We report results of an investigation of the temperature dependence of the
+magnon and phonon frequencies in NiO. A combination of Brillouin - Mandelstam
+and Raman spectroscopies allowed us to elucidate the evolution of the phonon
+and magnon spectral signatures from the Brillouin zone center (GHz range) to
+the second-order peaks from the zone boundary (THz range). The
+temperature-dependent behavior of the magnon and phonon bands in the NiO
+spectrum indicates the presence of antiferromagnetic (AF) order fluctuation or
+a persistent AF state at temperatures above the Neel temperature (T=523 K).
+Tuning the intensity of the excitation laser provides a method for
+disentangling the features of magnons from acoustic phonons without the
+application of a magnetic field. Our results are useful for interpretation of
+the inelastic-light scattering spectrum of NiO, and add to the knowledge of its
+magnon properties important for THz spintronic devices.",1702.04366v1
+2017-02-22,Prediction of High Temperature Quantum Anomalous Hall Effect in Two Dimensional Transition-Metal Oxides,"Quantum anomalous Hall (QAH) insulator is a topological phase which exhibits
+chiral edge states in the absence of magnetic field. The celebrated Haldane
+model is the first example of QAH effect, but difficult to realize. Here, we
+predict the two-dimensional single-atomic-layer V2O3 with a honeycomb-Kagome
+structure is a QAH insulator with a large band gap (large than 0.1 eV) and a
+high ferromagnetic Curie temperature (about 900 K). Combining the
+first-principle calculations with the effective Hamiltonian analysis, we find
+that the spin-majority dxy and dyz orbitals of V atoms on the honeycomb lattice
+form a massless Dirac cone near the Fermi level which becomes massive when the
+on-site spin-orbit coupling is included. Interestingly, we find that the large
+band gap is caused by a cooperative effect of electron correlation and
+spin-orbit coupling. Both first-principle calculations and the effective
+Hamiltonian analysis confirm that 2D V2O3 has a non-zero Chern number (i.e.,
+one). Our work paves a new direction towards realizing the QAH effect at room
+temperature.",1702.07022v1
+2017-03-14,Thermal-error regime in high-accuracy gigahertz single-electron pumping,"Single-electron pumps based on semiconductor quantum dots are promising
+candidates for the emerging quantum standard of electrical current. They can
+transfer discrete charges with part-per-million (ppm) precision in nanosecond
+time scales. Here, we employ a metal-oxide-semiconductor silicon quantum dot to
+experimentally demonstrate high-accuracy gigahertz single-electron pumping in
+the regime where the number of electrons trapped in the dot is determined by
+the thermal distribution in the reservoir leads. In a measurement with
+traceability to primary voltage and resistance standards, the averaged pump
+current over the quantized plateau, driven by a \mbox{$1$-GHz} sinusoidal wave
+in the absence of magnetic field, is equal to the ideal value of $ef$ within a
+measurement uncertainty as low as $0.27$~ppm.",1703.04795v2
+2018-02-21,Design of Chern Insulating Phases in Honeycomb Lattices,"The search for robust examples of the magnetic version of topological
+insulators, referred to as quantum anomalous Hall insulators or simply Chern
+insulators, so far lacks success. Our groups have explored two distinct
+possibilities based on multiorbital 3d oxide honeycomb lattices. Each has a
+Chern insulating phase near the ground state, but materials parameters were not
+appropriate to produce a viable Chern insulator. Further exploration of one of
+these classes, by substituting open shell 3d with 4d and 5d counterparts, has
+led to realistic prediction of Chern insulating ground states. Here we recount
+the design process, discussing the many energy scales that are active in
+participating (or resisting) the desired Chern insulator phase.",1802.07411v1
+2018-04-06,Spatially modulated susceptibility in thin film La$_{2-x}$Ba$_x$CuO$_4$,"The high critical temperature superconductor Lanthanum Barium Copper Oxide
+(La2-xBaxCuO4 or LBCO) exhibits a strong anomaly in critical temperature at
+1/8th doping, nematicity, and other interesting properties. We report here
+Scanning Superconducting Quantum Interference Device (SQUID) imaging of the
+magnetic fields and susceptibility in a number of thin film LBCO samples with
+doping in the vicinity of the 1/8th anomaly. Spatially resolved measurements of
+the critical temperatures of these samples do not show a pronounced depression
+at 1/8th doping. They do, however, exhibit strong, nearly linear modulations of
+the susceptibility (""straie"") of multiple samples with surprisingly long
+periods of 1-4 microns. Counterintuitively, vortices trap in positions of
+largest diamagnetic susceptibility in these striae. Given the rich interplay of
+different orders in this material system and its known sensitivity to epitaxial
+strain, we propose phase separation as a possible origin of these features and
+discuss scenarios in which that might arise.",1804.02483v1
+2018-04-12,Stabilizing Single Ni adatoms on a Two-dimensional Porous Titania Overlayer at the SrTiO$_3$(110) Surface,"Nickel vapor-deposited on the SrTiO$_3$(110) surface was studied using
+scanning tunneling microscopy, photoemission spectroscopy (PES), and density
+functional theory calculations. This surface forms a (4 $\times$ 1)
+reconstruction, composed of a 2-D titania structure with periodic six- and
+ten-membered nanopores. Anchored at these nanopores, Ni single adatoms are
+stabilized at room temperature. PES measurements show that the Ni adatoms
+create an in-gap state located at 1.9 eV below the conduction band minimum and
+induce an upward band bending. Both experimental and theoretical results
+suggest that Ni adatoms are positively charged. Our study produces
+well-dispersed single-adatom arrays on a well-characterized oxide support,
+providing a model system to investigate single-adatom catalytic and magnetic
+properties.",1804.04461v1
+2018-04-17,"Synthesis and physical properties of Na$_x$TO$_2$ (T=Mn, Co) nanostructures for cathode materials in Na--ion batteries","We prepared Na$_x$TO$_2$ (T = Mn, Co) nanostructures to use as cathode
+material in Na-ion batteries. The Rietveld refinement of x-ray diffraction data
+confirms the hexagonal symmetry. Scanning and transmission electron microscopy
+measurements show hexagonal and rod-shape morphology for T = Co and Mn,
+respectively. The magnetic measurements indicate the presence of variable
+oxidation states of Mn/Co ions, but no long range ordering till 5~K. We find
+that the Na$_{0.6}$MnO$_2$ is highly insulating whereas Na$_{0.7}$CoO$_2$ is
+semiconducting in nature. The conduction in Na$_{0.7}$CoO$_2$ takes place
+through both variable range hopping (VRH) as well as activation mechanisms in
+different temperature ranges. However, for Na$_{0.6}$MnO$_2$ the VRH prevails
+at elevated temperatures. Furthermore, the coin cells have been fabricated and
+tested the electrochemical behavior using cyclic voltammetry, which confirms
+the reversibility of Na--ions during intercalation/de-intercalation.",1804.06157v1
+2019-05-07,Structure-mining: screening structure models by automated fitting to the atomic pair distribution function over large numbers of models,"A new approach is presented to obtain candidate structures from atomic pair
+distribution function (PDF) data in a highly automated way. It fetches, from
+web-based structural databases, all the structures meeting the experimenter's
+search criteria and performs structure refinements on them without human
+intervention. It supports both x-ray and neutron PDFs. Tests on various
+material systems show the effectiveness and robustness of the algorithm in
+finding the correct atomic crystal structure. It works on crystalline and
+nanocrystalline materials including complex oxide nanoparticles and nanowires,
+low-symmetry and locally distorted structures, and complicated doped and
+magnetic materials. This approach could greatly reduce the traditional
+structure searching work and enable the possibility of high-throughput
+real-time auto analysis PDF experiments in the future.",1905.02677v2
+2019-05-14,Fermi-Bose mixtures and BCS-BEC crossover in high-Tc superconductors,"In this review article we consider theoretically and give experimental
+support to the models of the Fermi-Bose mixtures and the BCS-BEC crossover
+compared with the strong-coupling approach, which can serve as the cornerstones
+on the way from high-temperature to room-temperature superconductivity in
+pressurized metallic hydrides. We discuss some key theoretical ideas and
+mechanisms proposed for unconventional superconductors (cuprates, pnictides,
+chalcogenides, bismuthates, diborides, heavy-fermions, organics, bilayer
+graphene, twisted graphene, oxide hetero-structures), superfluids and balanced
+or imbalanced ultracold Fermi gases in magnetic traps. We build a bridge
+between unconventional superconductors and recently discovered pressurized
+hydrides superconductors H3S and LaH10 with the critical temperature close to
+room temperature. We discuss systems with line of nodal Dirac points close to
+the Fermi surface, superconducting shape resonances and hyperbolic
+superconducting networks which are very important for the development of novel
+topological superconductors, for the energetics, for the applications in
+nano-electronics and quantum computations.",1905.05419v4
+2020-07-02,Terahertz spectroscopy evidence of possible 40 K superconductivity in rhenium-doped strontium ruthenates,"Strontium ruthenates have many similarities with copper oxide superconductors
+and are of particular interest for the investigation of the mechanisms and
+conditions which lead to high-temperature superconductivity. We report here on
+multiple experimental indications of superconductivity with onset at 40 K in
+strontium ruthenate doped by rhenium and selenium with chlorine used as the
+flux. The main experimental evidence arises from terahertz spectroscopy of this
+material followed by AC and DC magnetization, as well as measurements of its
+heat capacity and magnetoresistance. Structural and morphological studies
+revealed the heterophase nature of this polycrystalline material as well as the
+changes of lattice parameters relative to the original phases. Experimental
+data show a higher critical temperature on the surface compared to that of the
+bulk of the sample.",2007.06509v1
+2020-07-14,"Recent advances, perspectives and challenges in ferroelectric synapses","The multiple ferroelectric polarization tuned by external electric field
+could be used to simulate the biological synaptic weight. Ferroelectric
+synaptic devices have two advantages compared with other reported ones: One is
+the intrinsic switching of ferroelectric domains without invoking of defect
+migration as in resistive oxides contributes reliable performance in these
+ferroelectric synapses. Another tremendous advantage is the extremely low
+energy consumption because the ferroelectric polarization is manipulated by
+electric field which eliminate the Joule heating by current as in magnetic and
+phase change memory. Ferroelectric synapses are potential for the construction
+of low-energy and effective brain-like intelligent networks. Here we summarize
+recent pioneering work of ferroelectric synapses involving the structure of
+ferroelectric tunnel junctions (FTJs), ferroelectric diodes (FDs) and
+ferroelectric field effect transistors (FeFETs), respectively, and shed light
+on future work needed to accelerate their application for efficient neural
+network.",2007.06914v1
+2020-07-20,Anisotropic vortices on superconducting Nb(110),"We investigate the electronic properties of type-II superconducting Nb(110)
+in an external magnetic field. Scanning tunneling spectroscopy reveals a
+complex vortex shape which develops from circular via coffee bean-shaped to
+elliptical when decreasing the energy from the edge of the superconducting gap
+to the Fermi level. This anisotropy is traced back to the local density of
+states of Caroli-de-Gennes-Matricon states which exhibits a direction-dependent
+splitting. Oxidizing the Nb(110) surface triggers the transition from the clean
+to the dirty limit, quenches the vortex bound states, and leads to an isotropic
+appearance of the vortices. Density functional theory shows that the Nb(110)
+Fermi surface is stadium-shaped near the \Gamma point. Calculations within the
+Bogoliubov-de-Gennes theory using these Fermi contours consistently reproduce
+the experimental results.",2007.09924v1
+2013-08-08,"Effects of Edge Oxidation on the Structural, Electronic, and Magnetic Properties of Zigzag Boron Nitride Nanoribbons","The effects of edge chemistry on the relative stability and electronic
+properties of zigzag boron nitride nanoribbons (ZBNNRs) are investigated. Among
+all functional groups considered, fully hydroxylated ZBNNRs are found to be the
+most energetically stable. When an in-plane external electric field is applied
+perpendicular to the axis of both hydrogenated and hydroxylated ZBNNRs, a
+spin-polarized half-metallic state is induced, whose character is different
+than that predicted for ZGNRs. The onset field for achieving the half-metallic
+state is found to mainly depend on the width of the ribbon. Our results
+indicate that edge functionalization of ZBNNRs may open the way for the design
+of new nano-electronic and nano-spintronic devices.",1308.1894v1
+2013-08-13,Coulomb interaction and valley-orbit coupling in Si quantum dots,"The valley-orbit coupling in a few-electron Si quantum dot is expected to be
+a function of its occupation number N. We study the spectrum of multivalley Si
+quantum dots for 2 <= N <= 4, showing that, counterintuitively,
+electron-electron interaction effects on the valley-orbit coupling are
+negligible. For N=2 they are suppressed by valley interference, for N=3 they
+vanish due to spinor overlaps, and for N = 4 they cancel between different
+pairs of electrons. To corroborate our theoretical findings, we examine the
+experimental energy spectrum of a few-electron metal-oxide-semiconductor
+quantum dot. The measured spin-valley state filling sequence in a magnetic
+field reveals that the valley-orbit coupling is definitively unaffected by the
+occupation number.",1308.2728v1
+2014-03-11,Spin correlated electronic state on the surface of a spin-orbit Mott system (Layered Iridates),"Novel phases of two dimensional electron systems resulting from new surface
+or interface modified electronic structures have generated significant interest
+in material science. We utilize photoemission spectroscopy to show that the
+near-surface electronic structure of a bulk insulating iridate
+Sr$_3$Ir$_2$O$_7$ lying near metal-Mott insulator transition exhibit weak
+metallicity signified by finite electronic spectral weight at the Fermi level.
+The surface electrons exhibit a unique spin structure resulting from an
+interplay of spin-orbit, Coulomb interaction and surface quantum magnetism,
+distinct from a topological insulator state. Our results suggest the
+experimental realization of a novel quasi two dimensional interacting electron
+surface ground state, opening the door for exotic quantum entanglement and
+transport phenomena in iridate-based oxide devices.",1403.2704v1
+2014-03-14,Investigation on Mn$_{3-δ}$Ga/MgO interface for magnetic tunneling junctions,"The Mn$_3$Ga Heusler compound and related alloys are the most promising
+materials for the realization of spin-transfer-torque switching in magneto
+tunneling junctions. Improved performance can be achieved by high quality
+interfaces in these multilayered structured devices. In this context, the
+interface between Mn$_{1.63}$Ga and MgO is of particular interest because of
+its spin polarization properties in tunneling junctions. We performed a
+chemical characterization of the MgO/Mn$_{1.63}$Ga junction by hard x-ray
+photoelectron spectroscopy (HAXPES). The experiment indicated the formation of
+Ga-O bonds at the interface and evidenced changes in the local environment of
+Mn atoms in the proximity of the MgO film. In addition, we show that the
+insertion of a metallic Mg-layer interfacing the MgO and Mn--Ga film strongly
+suppresses the oxidation of gallium.",1403.3556v4
+2014-03-20,A New Type of Quantum Criticality in the Pyrochlore Iridates,"Magnetic fluctuations and electrons couple in intriguing ways in the vicinity
+of zero temperature phase transitions - quantum critical points - in conducting
+materials. Quantum criticality is implicated in non-Fermi liquid behavior of
+diverse materials, and in the formation of unconventional superconductors. Here
+we uncover an entirely new type of quantum critical point describing the onset
+of antiferromagnetism in a nodal semimetal engendered by the combination of
+strong spin-orbit coupling and electron correlations, and which is predicted to
+occur in the iridium oxide pyrochlores. We formulate and solve a field theory
+for this quantum critical point by renormalization group techniques, show that
+electrons and antiferromagnetic fluctuations are strongly coupled, and that
+both these excitations are modified in an essential way. This quantum critical
+point has many novel features, including strong emergent spatial anisotropy, a
+vital role for Coulomb interactions, and highly unconventional critical
+exponents. Our theory motivates and informs experiments on pyrochlore iridates,
+and constitutes a singular realistic example of a non-trivial quantum critical
+point with gapless fermions in three dimensions.",1403.5255v1
+2016-11-09,Nanosize effect: Enhanced compensation temperature and existence of magneto-dielectric coupling in SmFeO3,"In transition metal oxides, quantum confinement arising from a large surface
+to volume ratio often gives rise to novel physico-chemical properties at
+nanoscale. Their size dependent properties have potential applications in
+diverse areas, including therapeutics, imaging, electronic devices,
+communication systems, sensors, and catalysis. We have analyzed structural,
+magnetic, dielectric, and thermal properties of weakly ferromagnetic SmFeO3
+nanoparticles of sizes about 55 nm and 500 nm. The nano-size particles exhibit
+several distinct features that are neither observed in their larger-size
+variants nor reported previously for the single crystals. In particular, for
+the 55 nm particle, we observe six-fold enhancement of compensation
+temperature, an unusual rise in susceptibility in the temperature range 550 to
+630 K due to spin pinning, and coupled antiferromagnetic-ferroelectric
+transition, directly observed in the dielectric constant.",1611.02850v2
+2016-11-22,The interface between Sr$_2$RuO$_4$ and Ru-metal inclusion--Implications for its superconductivity,"Under various conditions of the growth process, when the presumably
+unconventional superconductor Sr$_2$RuO$_4$ (SRO) contains micro-inclusions of
+Ru metal, the superconducting critical temperature increases significantly. An
+STEM study shows a sharp interface geometry which allows crystals of SRO and of
+Ru-metal to grow side by side by forming a commensurate superlattice structure
+at the interface. In an attempt to shed light as to why this happens, we
+investigated the atomic structure and electronic properties of the interface
+between the oxide and the metal micro-inclusions using density functional
+theory (DFT) calculations. Our results support the observed structure
+indicating that it is energetically favored over other types of Ru-metal/SRO
+interfaces. We find that a $t_{2g}$-$e_g$ orbital mixing occurs at the
+interface with significantly enhanced magnetic moments. Based on our findings,
+we argue that an inclusion mediated interlayer coupling reduces phase
+fluctuations of the superconducting order parameter which could explain the
+observed enhancement of the superconducting critical temperature in SRO samples
+containing micro-inclusions.",1611.07130v1
+2017-01-05,Relationship between electronic and crystal structure in Nd1+xBa2-xCu3O6+d,"In accordance with a relation between the lattice parameter c and the
+concentration of holes p, which has been found earlier for the YBa2Cu3O6+d
+compound, we obtain the p parameter in the same manner for the solid solution
+Nd1.2Ba1.8Cu3O6+d with substitution of Nd3+ for Ba2+ in barium sites. For this,
+structural and superconducting properties of the Nd1.2Ba1.8Cu3O6+d samples
+stored for specified times t after quenching from annealing temperatures have
+been studied. The investigation shows that Nd1.2Ba1.8Cu3O6+d stored for a long
+time has quite a low critical temperature Tc extending only to Tconset = 55 K
+for the most oxidized sample with d = 0.953. We find that the d-dependence of
+the lattice parameter c significantly changes with time t. When using the
+relation between c and p, the existence of electron doping of 0.045 per Cu in
+Nd1.2Ba1.8Cu3O6+d can be inferred. This doping explains well reduced Tc in
+Nd1.2Ba1.8Cu3O6+d. In addition, we observe a local drop of Tc by up to 20 K for
+the samples with p ~ 0.095 (d ~ 0.8) similar to decreasing Tc known as ""anomaly
+1/8"".",1701.01397v2
+2017-01-16,A Deep Mixing Solution to the Aluminum and Oxygen Isotope Puzzles in Presolar Grains,"We present here the application of a model for a mass circulation mechanism
+in between the H-burning shell and the base of the convective envelope of low
+mass AGB stars, aimed at studying the isotopic composition of those presolar
+grains showing the most extreme levels of 18O depletion and high concentration
+of 26Mg from the decay of 26Al. The mixing scheme we present is based on a
+previously suggested magnetic-buoyancy process, already shown to account
+adequately for the formation of the main neutron source for slow neutron
+captures in AGB stars. We find that this scenario is also capable of
+reproducing for the first time the extreme values of the 17O/16O, the 18O/16O,
+and the 26Al/27Al isotopic ratios found in the mentioned oxide grains,
+including the highest amounts of 26Al there measured.",1701.04445v1
+2017-01-25,Excitonic giant-dipole potentials in cuprous oxide,"In this work we predict the existence of a novel species of Wannier excitons
+when exposed to crossed electric and magnetic fields. In particular, we present
+a theory of giant-dipole excitons in $\textrm{Cu}_2\rm O$ in crossed fields.
+Within our theoretical approach we perform a pseudoseparation of the
+center-of-mass motion for the field-dressed excitonic species, thereby
+obtaining an effective single-particle Hamiltonian for the relative motion. For
+arbitrary gauge fields we exactly separate the gauge-dependent kinetic energy
+terms from the effective single-particle interaction potential. Depending on
+the applied field strengths and the specific field orientation, the potential
+for the relative motion of electron and hole exhibits an outer well at spatial
+separations up to several micrometers and depths up to $380\, \mu \rm eV$,
+leading to possible permanent excitonic electric dipole moments of around three
+million Debye.",1701.08847v2
+2017-04-11,Tuning Interfacial Ferromagnetism in LaNiO$_3$/CaMnO$_3$ Superlattices by Stabilizing Non-Equilibrium Crystal Symmetry,"Perovskite oxide heterostructures offer an important path forward for
+stabilizing and controlling low-dimensional magnetism. One of the guiding
+design principles for these materials systems is octahedral connectivity. In
+superlattices composed of perovskites with different crystal symmetries,
+variation of the relative ratio of the constituent layers as well as the
+individual layer thicknesses gives rise to non-equilibrium crystal symmetries
+that, in turn, lead to unprecedented control of interfacial ferromagnetism. We
+have found that in superlattices of CaMnO$_3$ (CMO) and LaNiO$_3$ (LNO),
+interfacial ferromagnetism can be modulated by a factor of three depending on
+LNO and CMO layer thicknesses as well as their relative ratio. Such an effect
+is only possible due to the non-equilibrium crystal symmetries at the
+interfaces and can be understood in terms of the anisotropy of the exchange
+interactions and modifications in the interfacial Ni-O-Mn and Mn-O-Mn bond
+angles and lengths with increasing LNO layer thickness. These results
+demonstrate the potential of engineering non-equilibrium crystal symmetries in
+designing ferromagnetism.",1704.03154v2
+2017-04-25,Strain-controlled Insulator-Metal Transition in YTiO3/SrTiO3 Superlattices: A First-Principles Study,"The structural, magnetic, and electronic properties of (STO)$_4$/(YTO)$_2$
+superlattice consisting of Mott insulator YTiO$_3$ (YTO) and band insulator
+SrTiO$_3$ (STO) under strain are investigated by the density-functional-theory
+plus \emph{U} method. It is found that an insulator-metal transition occurs
+when a compressive strain of 0.2\% is applied. The structural analyses reveal
+that the presence of metallic state in such superlattices accompanies
+structural phase transition with restoring of inversion symmetry. Further study
+shows that this strain-induced structural transition makes the $d$ energy level
+of the interfacial Ti atoms of the YTO layer move upward due to the decreasing
+of the TiO$_{6}$ octahedral volume and induces the electron reconstruction in
+the whole superlattice systems. In addition, when the on-site interaction $U$
+is changed from 5 to 4 eV, a similar insulator-metal transition also occurs in
+such superlattices due to the weakened electron correlation. These findings can
+improve our understanding of the insulator-metal transitions in such oxide
+superlattices.",1704.07687v1
+2018-05-09,Hund nodal line semimetals: The case of twisted magnetic phase in the double-exchange model,"We propose a class of topological metals, which we dub \emph{Hund nodal line
+semimetals}, arising from the strong Coulomb interaction encoded in the Hund's
+coupling between itinerant electrons and localized spins. We here consider a
+particular twisted spin configuration, which is realized in the double exchange
+model which describes the manganite oxides. The resulting effective tetragonal
+lattice of electrons with hoppings tied to the local spin features an
+antiunitary \emph{non-symmorphic} symmetry that in turn, together with another
+non-symmorphic but unitary, glide mirror symmetry, protects crossings of a
+double pair of bands along a high-symmetry line on the Brillouin zone boundary.
+We also discuss symmetry breaking arising from various perturbations of the
+twisted phase. Our results may motivate further studies of other realizations
+of this state of matter, for instance in different spin backgrounds, properties
+of its drumhead surface states, as well as its stability to disorder and
+interactions among the itinerant electrons.",1805.03640v2
+2018-05-30,The role of interstitial hydrogen in SrCoO$_{2.5}$ antiferromagnetic insulator,"Hydrogen exhibits qualitatively different charge states depending on the host
+material, as nicely explained by the state-of-the-art impurity-state
+calculation. Motivated by a recent experiment [Nature 546, 124 (2017)], we show
+that the complex oxide SrCoO$_{2.5}$ represents an interesting example, in
+which the interstitial H appears as a deep-level center according to the
+commonly-used transition level calculation, but no bound electron can be found
+around the impurity. Via a combination of charge difference analysis, density
+of states projection and constraint magnetization calculation, it turns out
+that the H-doped electron is spontaneously trapped by a nonunique Co ion and is
+fully spin-polarized by the onsite Hund's rule coupling. Consequently, the
+doped system remains insulating, whereas the antiferromagnetic exchange is
+slightly perturbed locally.",1805.11766v2
+2008-07-11,Electronic liquid crystal state in the high-temperature superconductor YBCO(6.45),"Electronic phases with symmetry properties matching those of conventional
+liquid crystals have recently been discovered in transport experiments on
+semiconductor heterostructures and metal oxides at milli-Kelvin temperatures.
+We report the spontaneous onset of a onedimensional, incommensurate modulation
+of the spin system in the high-temperature superconductor YBa2Cu3O6.45 upon
+cooling below ~150 K, while static magnetic order is absent above 2 K. The
+evolution of this modulation with temperature and doping parallels that of the
+in-plane anisotropy of the resistivity, indicating an electronic nematic phase
+that is stable over a wide temperature range. The results suggest that soft
+spin fluctuations are a microscopic route towards electronic liquid crystals,
+and nematic order can coexist with high-temperature superconductivity in
+underdoped cuprates.",0807.1861v1
+2009-12-05,"Structural, electrical and magnetic properties of Mo1-xFexO2 (x=0-0.05) thin films grown by pulsed laser ablation","We report the growth of undoped and Fe (2 and 5 at. percentage) doped
+molybdenum oxide thin films on c-plane of sapphire substrate using pulsed laser
+ablation. X-ray diffraction results show that the films are oriented in (100)
+direction and have monoclinic structure based on MoO2 phase as also supported
+by Raman spectroscopy. The x-ray photoelectron spectroscopy reveals chemical
+state of Fe is +2, which favors the substitutional occupancy of Fe ion in the
+MoO2 matrix. The room temperature resistivity of all the films are very low
+(approx.100 microohm-cm). The Fe doped samples show ferromagnetic behavior at
+room temperature.",0912.0978v1
+2009-12-06,Spectrum of extended systems from Reduced Density Matrix Functional Theory,"We present a method for calculating the spectrum of extended solids within
+reduced density matrix functional theory. An application of this method to the
+strongly correlated transition metal oxide series demonstrates that (i) an
+insulating state is found in the absence of magnetic order and, in addition,
+(ii) the interplay between the change transfer and Mott-Hubbard correlation is
+correctly described. In this respect we find that while NiO has a strong charge
+transfer character to the electronic gap, with substantial hybridization
+between $t_{2g}$ and oxygen-$p$ states in the lower Hubbard band, for MnO this
+is almost entirely absent. As a validation of our method we also calculate the
+spectra for a variety of weakly correlated materials, finding good agreement
+with experiment and other techniques.",0912.1118v2
+2009-12-17,"Multiferroic double perovskites: Opportunities, Issues and Challenges","Despite the great technological and scientific importance, a well-controlled
+coupled behavior in magnetoelectric multiferroic materials at room temperature
+remains challenging. We demonstrate that the self-ordered A2BBO6 (e.g., A = La,
+B = Mn, and B = Ni) double perovskites provide a unique alternative opportunity
+to control and/or to induce such behavior in oxides. In this paper, we outline
+and discuss the various challenges and bottleneck issues related to this class
+of materials using La2NiMnO6 as a prototype. Details of the synthesis
+strategies, using pulsed laser deposition as a central tool, to obtain a
+meticulous control over cation ordering is illustrated. The possible impact of
+Ni/Mn cation ordering on the magnetic ground states, ferromagnetic transition
+temperature, phonon behavior, and spin-phonon coupling are presented. Our
+results are also compared with the current literature on related compounds.",0912.3292v1
+2009-12-21,Electronic Ferroelectricity and Frustration,"Beyond a conventional classification of ferroelectricity, there is a class of
+materials where electronic degrees of freedom and electronic interactions are
+directly responsible for electric polarization and ferroelectric transition.
+This is termed electronic ferroelectricity. In this article, we review
+electronic ferroelectricity from a view point of frustration. Experimental and
+theoretical examinations in spin driven ferroelectric materials, recently
+termed multiferroics, are introduced. Spin frustration caused by competing
+magnetic interactions is of prime importance for this type of ferroelectricity.
+Charge driven ferroelectricity where electronic charge order induces electric
+polarization is reviewed. In particular, exotic dielectric and
+magneto-dielectric properties in layered iron oxides are focused on. Through a
+number of recent experimental and theoretical researches, charge fluctuation
+due to frustrated geometry plays essential roles on electronic ferroelectricity
+in this compound.",0912.4083v1
+2011-11-14,Layer-by-layer epitaxial growth of polar FeO(111) thin films on MgO(111),"We report on the structural properties of epitaxial FeO layers grown by
+molecular beam epitaxy on MgO(111). The successful stabilization of polar FeO
+films as thick as 16 monolayers (ML), obtained by deposition and subsequent
+oxidation of single Fe layers, is presented. FeO/MgO(111) thin films were
+chemically and structurally characterized using low-energy electron
+diffraction, Auger electron spectroscopy and conversion electron Mossbauer
+spectroscopy (CEMS). Detailed in situ CEMS measurements as a function of the
+film thickness demonstrated a size-effect-induced evolution of the hyperfine
+parameters, with the thickest film exhibiting the bulk-wustite hyperfine
+pattern. Ex situ CEMS investigation confirmed the magnetic ordering of the
+wustite thin film phase at liquid nitrogen temperature.",1111.3161v1
+2011-11-21,Ab initio Derivation of Correlated Superatom Model for Potassium Loaded Zeolite A,"We derive an effective low-energy Hamiltonian for potassium loaded zeolite A,
+a unique ferromagnet from non-magnetic elements. We perform ab initio density
+functional calculations and construct maximally localized Wannier functions for
+low-energy states made from potassium s electrons. The resulting Wannier
+orbitals, spreading widely in the alminosilicate cage, are found to be the
+superatomic s and p orbitals in the confining potential formed by the host
+cage. We then make a tight-binding model for these superatomic orbitals and
+introduce interaction parameters such as the Hubbard U. After mean-field
+calculations for the effective model, we find that ab initio spin density
+functional results are well reproduced by choosing appropriate sets of the
+interaction parameters. The interaction parameters turn out to be as large as
+the band width, $\sim$ 0.5 eV, indicating the importance of electron
+correlation, and that the present system is an interesting analog of correlated
+multi-orbital transition metal oxides.",1111.4815v2
+2011-11-25,Exact diagonalization results for resonant inelastic x-ray scattering spectra of one-dimensional Mott insulators,"We examine the momentum-dependent excitation spectra of indirect as well as
+direct resonant inelastic x-ray scattering (RIXS) processes in half-filled
+(extended) Hubbard rings. We determine the fundamental features of the
+groundstate RIXS response and discuss the experimental conditions that can
+allow for the low-energy part of these features to be distinguished in
+one-dimensional copper-oxide materials, focusing particularly on the different
+magnetic excitations occurring in indirect and direct RIXS processes. We study
+the dependence of spin and charge excitations on the choice of and detuning
+from resonance. Moreover, final state excitation weights are calculated as a
+function of the core-hole potential strength and lifetime. We show that these
+results can be used to determine material characteristics, such as the
+core-hole properties, from RIXS measurements.",1111.6028v2
+2012-01-04,Non-Kondo mechanism for resistivity minimum in spin ice conduction systems,"We present a mechanism of resistivity minimum in conduction electron systems
+coupled with localized moments, which is distinguished from the Kondo effect.
+Instead of the spin-flip process in the Kondo effect, electrons are elastically
+scattered by local spin correlations which evolve in a particular way under
+geometrical frustration as decreasing temperature. This is demonstrated by the
+cellular dynamical mean-field theory for a spin-ice type Kondo lattice model on
+a pyrochlore lattice. Peculiar temperature dependences of the resistivity,
+specific heat, and magnetic susceptibility in the non-Kondo mechanism are
+compared with the experimental data in metallic Ir pyrochlore oxides.",1201.0929v2
+2012-04-15,A Structural Phase Transition in Ca3Co4O9 Associated with Enhanced High Temperature Thermoelectric Properties,"Temperature dependent electrical resistivity, crystal structure and heat
+capacity measurements reveal a resistivity drop and metal to semiconductor
+transition corresponding to first order structural phase transition near 400 K
+in Ca3Co4O9. The lattice parameter c varies smoothly with increasing
+temperature, while anomalies in the a, b1 and b2 lattice parameters occur at ~
+400 K. Both Ca2CoO3 and CoO2 layers become distorted above ~ 400 K associated
+with the metal to semiconductor transport behavior change. Resistivity and heat
+capacity measurements as a function of temperature under magnetic field
+indicates low spin contribution to this transition. Reduced resistivity
+associated with this first order phase transition from metallic to
+semiconducting behavior enhances the thermoelectric properties at high
+temperatures and points to the metal to semiconductor transition as a mechanism
+for improved ZT in high temperature thermoelectric oxides.",1204.3231v1
+2013-09-20,Jeff=1/2 Mott spin-orbit insulating state close to the cubic limit in Ca4IrO6,"The Jeff=1/2 state is manifested in systems with large cubic crystal field
+splitting and spin-orbit coupling that are comparable to the on-site Coulomb
+interaction, U. 5d transition metal oxides host parameters in this regime and
+strong evidence for this state in Sr2IrO4, and additional iridates, has been
+presented. All the candidates, however, deviate from the cubic crystal field
+required to provide an unmixed canonical Jeff=1/2 state, impacting the
+development of a robust model of this novel insulating and magnetic state. We
+present results that not only show Ca4IrO6 hosts the state, but furthermore
+uniquely resides close to the ideal case required for an unmixed Jeff=1/2
+state.",1309.5411v1
+2014-06-29,Evidence for a Finite Temperature Insulator,"In superconductors the zero-resistance current-flow is protected from
+dissipation at finite temperatures (T) by virtue of the short-circuit condition
+maintained by the electrons that remain in the condensed state. The recently
+suggested finite-T insulator and the ""superinsulating"" phase are different
+because any residual mechanism of conduction will eventually become dominant as
+the finite-T insulator sets-in. If the residual conduction is small it may be
+possible to observe the transition to these intriguing states. We show that the
+conductivity of the high magnetic-field insulator terminating superconductivity
+in amorphous indium-oxide exhibits an abrupt drop, and seem to approach a zero
+conductance at T<0.04 K. We discuss our results in the light of theories that
+lead to a finite-T insulator.",1406.7510v4
+2015-12-18,Substrate-tuning of correlated spin-orbit oxides,"We have systematically investigated substrate-strain effects on the
+electronic structures of two representative Sr-iridates, a correlated-insulator
+Sr$_2$IrO$_4$ and a metal SrIrO$_3$. Optical conductivities obtained by the
+\emph{ab initio} electronic structure calculations reveal that the tensile
+strain shifts the optical peak positions to higher energy side with altered
+intensities, suggesting the enhancement of the electronic correlation and
+spin-orbit coupling (SOC) strength in Sr-iridates. The response of the
+electronic structure upon tensile strain is found to be highly correlated with
+the direction of magnetic moment, the octahedral connectivity, and the SOC
+strength, which cooperatively determine the robustness of $J_{eff}$=1/2 ground
+states. Optical responses are analyzed also with microscopic model calculation
+and compared with corresponding experiments. In the case of SrIrO$_3$, the
+evolution of the electronic structure near the Fermi level shows high
+tunability of hole bands, as suggested by previous experiments.",1512.05932v1
+2015-12-30,Topological insulator associated with quantum anomalous Hall phase in ferromagnetic perovskite superlattices,"We do a search for topological insulators which are associated with
+ferromagnetic ordering and show anomalous quantum Hall effect, among transition
+metal oxide superlattices taking the parent compounds as LaAlO3 and SrTiO3.
+Among the various superlattices which are studied here, (LaAlO3)10/(LaOsO3)2
+exhibits a ferromagnetic ground state with a topologically non-trivial energy
+gap when a spin-orbit interaction is turned on. The study of transverse
+conductivity shows that the system has quantized Hall conductivity inside the
+topological energy gap without applying any external magnetic field. The
+ferromagnetic order parameters and the ordering temperature (Tc) have been
+estimated by taking a simple Heisenberg model of ferromagnetism.",1512.08843v1
+2016-05-13,Controlling Kondo-like Scattering at the SrTiO3-based Interfaces,"The observation of magnetic interaction at the interface between nonmagnetic
+oxides has attracted much attention in recent years. In this report, we show
+that the Kondo-like scattering at the SrTiO3-based conducting interface is
+enhanced by increasing the lattice mismatch and growth oxygen pressure PO2. For
+the 26-unit-cell LaAlO3/SrTiO3 (LAO/STO) interface with lattice mismatch being
+3.0%, the Kondo-like scattering is observed when PO2 is beyond 1 mTorr. By
+contrast, when the lattice mismatch is reduced to 1.0% at the
+(La0.3Sr0.7)(Al0.65Ta0.35)O3/SrTiO3 (LSAT/STO) interface, the metallic state is
+always preserved up to PO2 of 100 mTorr. The data from Hall measurement and
+X-ray absorption near edge structure (XANES) spectroscopy reveal that the
+larger amount of localized Ti3+ ions are formed at the LAO/STO interface
+compared to LSAT/STO. Those localized Ti3+ ions with unpaired electrons can be
+spin-polarized to scatter mobile electrons, responsible for the Kondo-like
+scattering observed at the LAO/STO interface.",1605.04038v1
+2016-05-23,Soft X-ray Absorption Spectroscopy Study of Multiferroic Bi-substituted Ba(1-x)Bi(x)Ti(0.9)Fe(0.1)O(3),"The electronic structures of multiferroic oxides of
+Ba(1-x)Bi(x)Ti(0.9)Fe(0.1)O(3) (0 < x < 0.12) have been investigated by
+employing photoemission spectroscopy and soft x-ray absorption spectroscopy
+(XAS). The measured Fe and Ti 2p XAS spectra show that Ti ions are in the Ti4+
+states for all x and that Fe ions are Fe2+-Fe3+ mixed-valent for x > 0. The
+valence states of Fe ions are found to be nearly trivalent for x=0, and
+decreases with increasing x from being nearly trivalent (v(Fe)~ 3) for x=0 to
+v(Fe)~ 2.6 for x=0.12. The valence states of both Ti and Ba ions do not change
+for all x < 0.12. Based on the obtained valence states of Fe ions, the
+electronic and magnetic properties of Ba(1-x)Bi(x)Ti(0.9)Fe(0.1)O(3) are
+explored.",1605.06869v1
+2016-12-14,Bulk superconductivity at 84 K in the strongly overdoped regime of cuprates,"By means of magnetization, specific heat and muon-spin relaxation
+measurements, we investigate high-pressure oxidized \mohpo, in which overdoping
+is achieved up to $p \sim 0.45$ hole/Cu, well beyond the $T_c - p$
+superconducting dome of cuprates, where Fermi liquid behavior is expected.
+Surprisingly, we find bulk superconductivity with $T_c$=84 K and superfluid
+density similar to those of optimally doped Y123. On the other hand, specific
+heat data display a large electronic contribution at low temperature,
+comparable to that of nonsuperconducting overdoped La214. These results point
+at an unusual high-$T_c$ phase with a large fraction of unpaired holes. Further
+experiments may assess the Fermi liquid properties of the present phase, which
+would put into question the paradigm that the high $T_c$ of cuprates originates
+from a non-Fermi liquid ground state.",1612.04707v1
+2016-12-15,Correlation-Induced Band Competition in SrTiO3/LaAlO3,"The oxide interface SrTiO3/LaAlO3 supports a 2D electron liquid displaying
+superconductivity and magnetism, while allowing for a continuous control of the
+electron density using a gate. Our recent measurements have shown a similar
+surprising nonmonotonic behavior as function of the gate voltage (carrier
+density) of three quantities: the superconducting critical temperature and
+field, the inverse Hall coefficient, and the frequency of quantum oscillations.
+While the total density has to be monotonic as function of gate, the last
+result indicates that one of the involved bands has a nonmontonic occupancy as
+function of the chemical potential. We show how electronic interactions can
+lead to such an effect, by creating a competition between the involved bands
+and making their structure non-rigid, and thus account for all these effects.
+Adding Fock terms to our previous Hartree treatment makes this scenario even
+more generic.",1612.05094v4
+2016-12-20,Enhanced Superconductivity in TiO Epitaxial Thin Films,"Titanium oxides have many fascinating optical and electrical properties, such
+as the superconductivity at 2.0 K in cubic titanium monoxide TiO
+polycrystalline bulk. However, the lack of TiO single crystals or epitaxial
+films has prevented systematic investigations on its superconductivity. Here,
+we report the basic superconductivity characterizations of cubic TiO films
+epitaxially grown on (0001)-oriented Al2O3 substrates. The magnetic and
+electronic transport measurements confirmed that TiO is a type-II
+superconductor and the record high Tc is about 7.4 K. The lower critical field
+(Hc1) at 1.9 K, the extrapolated upper critical field Hc2(0) and coherence
+length are about 18 Oe, 13.7 T and 4.9 nm, respectively. With increasing
+pressure, the value of Tc shifts to lower temperature while the normal state
+resistivity increases. Our results on the superconducting TiO films confirm the
+strategy to achieve higher Tc in epitaxial films, which may be helpful for
+finding more superconducting materials in various related systems.",1612.06506v1
+2016-12-30,Itinerant Antiferromagnetism in RuO$_{2}$,"Bulk rutile RuO$_2$ has long been considered a Pauli paramagnet. Here we
+report that RuO$_2$ exhibits a hitherto undetected lattice distortion below
+approximately 900 K. The distortion is accompanied by antiferromagnetic order
+up to at least 300 K with a small room temperature magnetic moment of
+approximately 0.05 $\mu_B$ as evidenced by polarized neutron diffraction.
+Density functional theory plus $U$ (DFT+$U$) calculations indicate that
+antiferromagnetism is favored even for small values of the Hubbard $U$ of the
+order of 1 eV. The antiferromagnetism may be traced to a Fermi surface
+instability, lifting the band degeneracy imposed by the rutile crystal field.
+The combination of high N\'eel temperature and small itinerant moments make
+RuO$_2$ unique among ruthenate compounds and among oxide materials in general.",1612.09589v1
+2017-06-06,Time-spliced X-ray Diffraction Imaging,"Diffraction imaging of non-equilibrium dynamics at atomic resolution is
+becoming possible with X-ray free-electron lasers. However, there are
+unresolved problems with applying this method to objects that are confined in
+only one dimension. Here I show that one-dimensional coherent diffraction
+imaging is possible by splicing together images recovered from different delays
+in a time-resolved experiment. This is used to image the time and space
+evolution of antiferromagnetic order in a complex oxide heterostructure from
+measurements of a resonant soft X-ray diffraction peak. Mid-infrared excitation
+of the substrate is shown to lead to a magnetic front that propagates at a
+velocity exceeding the speed of sound, a critical observation for the
+understanding of driven phase transitions in complex condensed matter.",1706.01718v3
+2017-06-20,High-pressure synthesis of an unusual antiferromagnetic metal CaCoO$_{3}$ with GdFeO$_{3}$-type perovskite structure,"The GdFeO$_{3}$-type perovskite CaCoO$_{3}$ has been successfully synthesized
+by high-pressure oxygen annealing for the oxygen deficient perovskite. A
+detailed structural analysis based on synchrotron X-ray diffraction data and a
+thermogravimetric analysis show that the valence of Co is +4 and the sample is
+free from oxygen deficiency. This compound shows an antiferromagnetic ordering
+at 95 K, which has presumably helical spin arrangement, with keeping the
+incoherent metallic state down to the lowest temperature. This work
+demonstrates that the Co$^{4+}$-perovskite oxides exhibit a variety of magnetic
+phases by the band-width control through the lattice distortion.",1706.06373v2
+2017-06-16,An argon ion beam milling process for native $\text{AlO}_\text{x}$ layers enabling coherent superconducting contacts,"We present an argon ion beam milling process to remove the native oxide layer
+forming on aluminum thin films due to their exposure to atmosphere in between
+lithographic steps. Our cleaning process is readily integrable with
+conventional fabrication of Josephson junction quantum circuits. From
+measurements of the internal quality factors of superconducting microwave
+resonators with and without contacts, we place an upper bound on the residual
+resistance of an ion beam milled contact of 50$\,\mathrm{m}\Omega \cdot \mu
+\mathrm{m}^2$ at a frequency of 4.5 GHz. Resonators for which only $6\%$ of the
+total foot-print was exposed to the ion beam milling, in areas of low electric
+and high magnetic field, showed quality factors above $10^6$ in the single
+photon regime, and no degradation compared to single layer samples. We believe
+these results will enable the development of increasingly complex
+superconducting circuits for quantum information processing.",1706.06424v1
+2017-10-30,Strain induced Jahn-Teller distortions in BaFeO3 : A first-principles study,"The effect of epitaxial strain on structural, magnetic and electronic
+properties of BaFeO 3 per- ovskite oxide are investigated from first principles
+calculations, using the Density Functional The- ory (DFT) plus the Hubbard
+approach (DFT+U) within the Generalized Gradient Approximation (GGA). Hybrid
+functional calculations, based on mixed exact Hartree-Fock (HF) and DFT
+exchange energy functionals, are also performed. For the ground state
+calculations,the DFT+U is found more suitable to describe the half metallic and
+ferromagnetic state of cubic BaFeO 3 . The possible oc- curence of oxygen
+octahedra rotations, Jahn-Teller distortions and charge orderings through
+biaxial strain are explored. The obtained results reveal that the Jahn-teller
+distortion is induced under tensile biaxial strain while the oxygen octahedra
+rotations and breathing are unusualy not observed. Then, the strained BaFeO 3
+is considered as a particular Jahn-Teller distorted perovskite with excep-
+tional properties when compared to CaFeO 3 and SrFeO 3 . These findings lead to
+a strain engineering of the JT distortions in BaFeO 3 , and thus for high
+fundamental and technological interests.",1710.10997v1
+2017-11-30,Nonlinear Pauli Susceptibilities in Sr$_3$Ru$_2$O$_7$ and Universal Features of Itinerant Metamagnetism,"We report, for the first time, measurements of the third order, $\chi_3$ and
+fifth order, $\chi_5$, susceptibilities in an itinerant oxide metamagnet,
+Sr$_3$Ru$_2$O$_7$ for magnetic fields both parallel and perpendicular to the
+c-axis. These susceptibilities exhibit maxima in their temperature dependence
+such that $T_1 \approx 2T_3 \approx 4T_5$ where the $T_i$ are the position in
+temperature where a peak in the $i$-th order susceptibility occurs. These
+features taken together with the scaling of the critical field with the
+temperature $T_1$ observed in a diverse variety of itinerant metamagnets find a
+natural explanation in a single band model with one Van Hove singularity (VHS)
+and onsite repulsion $U$. The separation of the VHS from the Fermi energy
+$\Delta$, sets a single energy scale, which is the primary driver for the
+observed features of itinerant metamagnetism at low temperatures.",1712.00113v1
+2017-12-04,Particle-hole symmetry reveals failed superconductivity in the metallic phase of two-dimensional superconducting films,"Electrons confined to two dimensions display an unexpected diversity of
+behaviors as they are cooled to absolute zero. Noninteracting electrons are
+predicted to eventually ""localize"" into an insulating ground state, and it has
+long been supposed that electron correlations stabilize only one other phase:
+superconductivity. However, many two-dimensional (2D) superconducting materials
+have shown surprising evidence for metallic behavior, where the electrical
+resistivity saturates in the zero-temperature limit, the nature of this
+unexpected metallic state remains under intense scrutiny. We report electrical
+transport properties for two disordered 2D superconductors, indium oxide and
+tantalum nitride, and observe a magnetic field-tuned transition from a true
+superconductor to a metallic phase with saturated resistivity. This metallic
+phase is characterized by a vanishing Hall resistivity, suggesting that it
+retains particle-hole symmetry from the disrupted superconducting state.",1712.00947v1
+2017-12-14,Muon spin relaxation and inelastic neutron scattering investigations of all-in/all-out antiferromagnet Nd2Hf2O7,"Nd2Hf2O7, belonging to the family of geometrically frustrated cubic rare
+earth pyrochlore oxides, was recently identified to order antiferromagnetically
+below T_N = 0.55 K with an all-in/all-out arrangement of Nd3+ moments, however
+with a much reduced ordered state moment. Herein we investigate the spin
+dynamics and crystal field states of Nd2Hf2O7 using muon spin relaxation (muSR)
+and inelastic neutron scattering (INS) measurements. Our muSR study confirms
+the long range magnetic ordering and shows evidence for coexisting persistent
+dynamic spin fluctuations deep inside the ordered state down to 42 mK. The INS
+data show the crytal electric field (CEF) excitations due to the transitions
+both within the ground state multiplet and to the first excited state
+multiplet. The INS data are analyzed by a model based on CEF and crystal field
+states are determined. Strong Ising-type anisotropy is inferred from the ground
+state wavefunction. The CEF parameters indicate the CEF-split Kramers doublet
+ground state of Nd3+ to be consistent with the dipolar-octupolar character.",1712.05201v1
+2017-12-26,Nanoscale electrical conductivity imaging using a nitrogen-vacancy center in diamond,"The electrical conductivity of a material can feature subtle, nontrivial, and
+spatially-varying signatures with critical insight into the material's
+underlying physics. Here we demonstrate a conductivity imaging technique based
+on the atom-sized nitrogen-vacancy (NV) defect in diamond that offers local,
+quantitative, and noninvasive conductivity imaging with nanoscale spatial
+resolution. We monitor the spin relaxation rate of a single NV center in a
+scanning probe geometry to quantitatively image the magnetic fluctuations
+produced by thermal electron motion in nanopatterned metallic conductors. We
+achieve 40-nm scale spatial resolution of the conductivity and realize a
+25-fold increase in imaging speed by implementing spin-to-charge conversion
+readout of a shallow NV center. NV-based conductivity imaging can probe
+condensed-matter systems in a new regime, and as a model example, we project
+readily achievable imaging of nanoscale phase separation in complex oxides.",1712.09209v1
+2018-09-13,In situ soft x-ray absorption spectroscopic study of Fe/MgO interfaces,"Interfacial reaction between iron and MgO has been studied in situ during
+deposition of iron on MgO surface, using soft x-ray absorption spectroscopy.
+High sensitivity of the technique which is capable of detecting even a sub
+monolayer of a given phase, combined with in situ measurements as a function of
+iron layer thickness, allowed one to make a quantitative estimate of
+interfacial phases. Two different substrates namely, MgO (001) single crystal,
+and a polycrystalline MgO film on Si substrate have been used in order to
+elucidate the role of the state of MgO surface in controlling the interface
+structure. It is found that at the interface of iron and MgO film, about two
+monolayers of Fe3O4 is formed. Fe3O4 being the oxide of iron with the highest
+heat of formation, the reaction appears to be controlled thermodynamically. On
+the other hand, on the interface with MgO (001) surface, FeO is formed,
+suggesting that the reaction is limited by the availability of oxygen atoms.
+Magnetic behaviour of the FeO layer gets modified significantly due to
+proximity effect of the bulk ferromagnetic iron layer.",1809.04782v2
+2018-10-15,Possible High TC Layered Ferromagnetic Insulator Sr2NiRuO4: An ab initio Study,"Magnetic insulators are often antiferromagnetic (AFM) and layered AFM
+compounds usually show low ordering temperature. On the other hand, layered
+ferromagnetic (FM) insulators with high-TC are very rare although they could be
+quite useful for spintronic applications. Here, using crystal field level
+analysis in combination with density functional theory calculations as well as
+Monte Carlo simulations, we predict that the layered insulator Sr2NiRuO4 would
+have a strong FM coupling with TC as high as 240 K. The tetragonal crystal
+field in the Ni-O-Ru square plane stabilizes the S=1/2 Ni+ and S=3/2 Ru3+
+states. The unique level ordering and occupation optimize the FM Ni-Ru
+superexchange interactions in the checkerboard arrangement, thus suggesting
+Sr2NiRuO4 as an unusual high-TC layered FM insulator. This work highlights the
+potential of charge-spin-orbital degrees of freedom for stabilizing strong FM
+coupling in layered oxides.",1810.06142v1
+2018-10-18,R1 dispersion contrast at high field with fast field-cycling MRI,"Contrast agents with a strong $R_1$ dispersion have been shown to be
+effective in generating target-specific contrast in MRI. The utilization of
+this $R_1$ field dependence requires the adaptation of a MRI scanner for fast
+field-cycling (FFC). Here, we present the first implementation and validation
+of FFC-MRI at a clinical field strength of 3 T. A field-cycling range of
+$\pm$100 mT around the nominal $B_0$ field was realized by inserting an
+additional insert coil into an otherwise conventional MRI system. System
+validation was successfully performed with selected iron oxide magnetic
+nanoparticles and comparison to FFC-NMR relaxometry measurements. Furthermore,
+we show proof-of-principle $R_1$ dispersion imaging and demonstrate the
+capability of generating R1 dispersion contrast at high field with suppressed
+background signal. With the presented ready-to-use hardware setup it is
+possible to investigate MRI contrast agents with a strong R1 dispersion at a
+field strength of 3 T.",1810.07930v1
+2018-10-02,"Design and development of a low temperature, inductance based high frequency ac susceptometer","We report on the development of an induction based low temperature high
+frequency ac susceptometer capable of measuring at frequencies up to 3.5 MHz
+and at temperatures between 2 K and 300 K. Careful balancing of the detection
+coils and calibration have allowed a sample magnetic moment resolution of
+$5\times10^{-10} Am^2$ at 1 MHz. We will discuss the design and
+characterization of the susceptometer, and explain the calibration process. We
+also include some example measurements on the spin ice material CdEr$_2$S$_4$
+and iron oxide based nanoparticles to illustrate functionality.",1810.09559v1
+2019-06-28,High pO2 Floating Zone Crystal Growth of the Perovskite Nickelate PrNiO3,"Single crystals of PrNiO3 were grown under an oxygen pressure of 295 bar
+using a unique high-pressure optical-image floating zone furnace. The crystals,
+with volume in excess of 1 mm3, were characterized structurally using single
+crystal and powder X-ray diffraction. Resistivity, specific heat, and magnetic
+susceptibility were measured, all of which evidenced an abrupt, first order
+metal-insulator transition (MIT) at ~130 K, in agreement with previous
+literature reports on polycrystalline specimens. Temperature-dependent single
+crystal diffraction was performed to investigate changes through the MIT. Our
+study demonstrates the opportunity space for high fugacity, reactive
+environments for single crystal growth specifically of perovskite nickelates
+but more generally to correlated electron oxides.",1907.00078v1
+2019-09-01,Observation of a charge-neutral muon-polaron complex in antiferromagnetic Cr$_2$O$_3$,"We report a comprehensive muon spin rotation ($\mu$SR) study of the
+prototypical magnetoelectric antiferromagnet Cr$_2$O$_3$. We find the
+positively charged muon ($\mu^+$) occupies several distinct interstitial sites,
+and displays a rich dynamic behavior involving local hopping, thermally
+activated site transitions and the formation of a charge-neutral complex
+composed of a muon and an electron polaron. The discovery of such a complex has
+implications for the interpretation of $\mu$SR spectra in a wide range of
+magnetic oxides, and opens a route to study the dopant characteristics of
+interstitial hydrogen impurities in such materials. We address implications
+arising from implanting a $\mu^+$ into a linear magnetoelectric, and discuss
+the challenges of observing a local magnetoelectric effect generated by the
+charge of the muon.",1909.00416v1
+2020-01-20,First-principles studies of electronic properties in Lithium metasilicate (Li2SiO3),"Lithium metasilicate (Li2SiO3) has attracted considerable interest as a
+promising electrolyte material for potential use in lithium batteries. However,
+its electronic properties are still not thoroughly understood. In this work,
+density functional theory calculations were adopted, our calculations find out
+that Li2SiO3 exhibits unique lattice symmetry (orthorhombic crystal), valence
+and conduction bands, charge density distribution, and van Hove singularities.
+Delicate analyses, the critical multi-orbital hybridizations in Li-O and Si-O
+bonds 2s- (2s, 2px, 2py, 2pz) and (3s, 3px, 3py, 3pz)- (2s, 2px, 2py, 2pz),
+respectively was identified. In particular, this system shows a huge
+indirect-gap of 5.077 eV. Therefore, there exist many strong covalent bonds,
+with obvious anisotropy and non-uniformity. On the other hand, the
+spin-dependent magnetic configurations are thoroughly absent. The theoretical
+framework could be generalized to explore the essential properties of cathode
+and anode materials of oxide compounds.",2001.07128v1
+2020-01-21,Field-Driven Gapless Spin Liquid in the Spin-1 Kitaev Honeycomb Model,"Recent proposals for spin-1 Kitaev materials, such as honeycomb Ni oxides
+with heavy elements of Bi and Sb, have shown that these compounds naturally
+give rise to antiferromagnetic (AFM) Kitaev couplings. Conceptual interest in
+such AFM Kitaev systems has been sparked by the observation of a transition to
+a gapless $U(1)$ spin liquid at intermediate field strengths in the AFM
+spin-1/2 Kitaev model. However, all hitherto known spin-1/2 Kitaev materials
+exhibit ferromagnetic bond-directional exchanges. Here we discuss the physics
+of the spin-1 Kitaev model in a magnetic field and show, by extensive numerical
+analysis, that for AFM couplings it exhibits an extended gapless quantum spin
+liquid at intermediate field strengths. The close analogy to its spin-1/2
+counterpart suggests that this gapless spin liquid is a $U(1)$ spin liquid with
+a neutral Fermi surface, that gives rise to enhanced thermal transport
+signatures.",2001.07699v1
+2020-02-16,"First-principles Study on Piezoelectricity and Spontaneous Polarization in Bi(Fe,Co)O3","Solid solution BiFe1-xCoxO3 shows anti-ferromagnetic order and pyroelectric
+order, simultaneously. It has been known that BiFe1-xCoxO3 exhibits a
+structural phase transition between monoclinic and tetragonal phases as x
+increases. This kinds of transition is often called morphotoropic phase
+boundary, which is well known to take place in a representative piezoelectric
+oxide, PbZr1-xTixO3. In order to theoretically understand the piezoelectric
+property in BiFe1-xCoxO3, we performed ab-initio electronic-structure
+calculations and studied the structural stability, the magnetic property, and
+the electronic polarization by means of super-cell approach. It turns out that
+the large electric polarization and the particular pyramidal coordination
+suppress the response of the electric polarization under strain. A way to
+enhance the piezoelectric effect in BiFe1-xCoxO3 is proposed.",2002.06510v1
+2020-02-23,Local polarization in oxygen-deficient LaMnO$_3$ induced by charge localization in the Jahn-Teller distorted structure,"The functional properties of transition metal perovskite oxides are known to
+result from a complex interplay of magnetism, polarization, strain, and
+stoichiometry. Here, we show that for materials with a cooperative Jahn-Teller
+distortion, such as LaMnO$_3$ (LMO), the orbital order can also couple to the
+defect chemistry and induce novel material properties. At low temperatures, LMO
+exhibits a strong Jahn-Teller distortion that splits the $e_g$ orbitals of the
+high-spin Mn$^{3+}$ ions and leads to alternating long, short, and intermediate
+Mn--O bonds. Our DFT+$U$ calculations show that, as a result of this orbital
+order, the charge localization in LMO upon oxygen vacancy formation differs
+from other manganites, like SrMnO$_3$, where the two extra electrons reduce the
+two Mn sites adjacent to the vacancy. In LMO, relaxations around the defect
+depend on which type of Mn--O bond is broken, affecting the $d$-orbital
+energies and leading to asymmetric and hence polar excess-electron localization
+with respect to the vacancy. Moreover, we show that the Mn--O bond lengths,
+orbital order and consequently the charge localization and polarity are tunable
+via strain.",2002.09921v1
+2020-04-03,Plasma-enhanced atomic layer deposition of nickel nanotubes with low resistivity and coherent magnetization dynamics for 3D spintronics,"We report plasma-enhanced atomic layer deposition (ALD) to prepare conformal
+nickel thin films and nanotubes by using nickelocene as a precursor, water as
+the oxidant agent and an in-cycle plasma enhanced reduction step with hydrogen.
+The optimized ALD pulse sequence, combined with a post-processing annealing
+treatment, allowed us to prepare 30 nm thick metallic Ni layers with a
+resistivity of 8 $\mu\Omega$cm at room temperature and good conformality both
+on the planar substrates and nanotemplates. Thereby we fabricated several
+micrometer-long nickel nanotubes with diameters ranging from 120 to 330 nm. We
+report on the correlation between ALD growth and functional properties of
+individual Ni nanotubes characterized in terms of magneto-transport and the
+confinement of spin wave modes. The findings offer novel perspectives for
+Ni-based spintronics and magnonic devices operated in the GHz frequency regime
+with a 3D device architecture.",2004.01592v2
+2020-12-07,Van der Waals Multiferroic Tunnel Junctions,"Multiferroic tunnel junctions (MFTJs) have aroused significant interest due
+to their functional properties useful for non-volatile memory devices. So far,
+however, all the existing MFTJs have been based on perovskite-oxide
+heterostructures limited by a relatively high resistance-area (RA) product
+unfavorable for practical applications. Here, using first-principles
+calculations, we explore spin-dependent transport properties of van der Waals
+(vdW) MFTJs which consist of two-dimensional (2D) ferromagnetic FenGeTe2 (n =
+3, 4, 5) electrodes and 2D ferroelectric In2Se3 barrier layers. We demonstrate
+that such FemGeTe2/In2Se3/FenGeTe2 (m, n = 3, 4, 5) MFTJs exhibit multiple
+non-volatile resistance states associated with different polarization
+orientation of the ferroelectric In2Se3 layer and magnetization alignment of
+the two ferromagnetic FenGeTe2 layers. We find a remarkably low RA product
+which makes the proposed vdW MFTJs superior to the conventional MFTJs in terms
+of their promise for non-volatile memory applications.",2012.03546v1
+2020-12-22,Crystalline symmetry-dependent magnon formation in itinerant ferromagnet SrRuO3,"SrRuO3 (SRO) is an itinerant ferromagnet with strong coupling between the
+charge, spin, and lattice degrees of freedom. This strong coupling suggests
+that the electronic and magnetic behaviors of SRO are highly susceptible to
+changes in the lattice distortion. Here we show how the spin interaction and
+resultant magnon formation change with the modification in the crystallographic
+orientation. We fabricated SRO epitaxial thin films with (100), (110), and
+(111) surface orientations, to systematically modulate the spin interaction and
+spin dimensionality. The reduced spin dimensionality and enhanced exchange
+interaction in the (111)-oriented SRO thin film significantly suppresses magnon
+formation. Our study comprehensively demonstrates the facile tunability of
+magnon formation and spin interaction in correlated oxide thin films.",2012.11865v1
+2021-01-19,Robust ferromagnetism in insulating La$_2$NiMnO$_6$ thin films,"The field of oxide spintronics can strongly benefit from the establishment of
+robust ferromagnetic insulators with near room-temperature Curie temperature.
+Here we investigate the structural, electronic, and magnetic properties of
+atomically-precise epitaxially-strained thin films of the double perovskite
+La$_2$NiMnO$_6$ (LNMO) grown by off-axis radio-frequency magnetron sputtering.
+We find that the films retain both a strong insulating behavior and a bulk-like
+Curie temperature in the order of 280 K, nearly independently from epitaxial
+strain conditions. These results suggest a prospective implementation of LNMO
+films in multi-layer device architectures where a high-temperature
+ferromagnetic insulating state is a prerequisite.",2101.07530v2
+2012-05-18,Measurements of the gate tuned superfluid density in superconducting LaAlO3/SrTiO3,"The interface between the insulating oxides LaAlO3 and SrTiO3 exhibits a
+superconducting two-dimensional electron system that can be modulated by a gate
+voltage. While gating of the conductivity has been probed extensively and
+gating of the superconducting critical temperature has been demonstrated, the
+question whether, and if so how, the gate tunes the superfluid density and
+superconducting order parameter is unanswered. We present local magnetic
+susceptibility, related to the superfluid density, as a function of
+temperature, gate voltage and location. We show that the temperature dependence
+of the superfluid density at different gate voltages collapse to a single curve
+characteristic of a full superconducting gap. Further, we show that the dipole
+moments observed in this system are not modulated by the gate voltage.",1205.4064v1
+2012-05-20,Dimensionality Driven Spin-Flop Transition in Layered Iridates,"Using resonant x-ray diffraction, we observe an easy c-axis collinear
+antiferromagnetic structure for the bilayer Sr$_3$Ir$_2$O$_7$, a significant
+contrast to the single layer Sr$_2$IrO$_4$ with in-plane canted moments. Based
+on a microscopic model Hamiltonian, we show that the observed spin-flop
+transition as a function of number of IrO$_2$ layers is due to strong
+competition among intra- and inter-layer bond-directional pseudo-dipolar
+interactions of the spin-orbit entangled $J_{eff}$=1/2 moments. With this we
+unravel the origin of anisotropic exchange interactions in a Mott insulator in
+the strong spin-orbit coupling regime, which holds the key to the various types
+of unconventional magnetism proposed in 5$d$ transition metal oxides.",1205.4381v1
+2017-05-01,High pressure floating-zone growth of perovskite nickelate LaNiO3 single crystals,"We report the first single crystal growth of the correlated metal LaNiO3
+using a high-pressure optical-image floating zone furnace. The crystals were
+studied using single crystal/powder x-ray diffraction, resistivity, specific
+heat, and magnetic susceptibility. The availability of bulk LaNiO3 crystals
+will (i) promote deep understanding in this correlated material, including the
+mechanism of enhanced paramagnetic susceptibility, and (ii) provide rich
+opportunities as a substrate for thin film growth such as important
+ferroelectric and/or multiferroic materials. This study demonstrates the power
+of high pO2 single crystal growth of nickelate perovskites and correlated
+electron oxides more generally.",1705.00570v1
+2017-05-06,Model of ultrafast demagnetization driven by spin-orbit coupling in a photoexcited antiferromagnetic insulator Cr2O3,"We theoretically study the dynamic time evolution following laser pulse
+pumping in an antiferromagnetic insulator Cr$_{2}$O$_{3}$. From the
+photoexcited high-spin quartet states to the long-lived low-spin doublet
+states, the ultrafast demagnetization processes are investigated by solving the
+dissipative Schr\""odinger equation. We find that the demagnetization times are
+of the order of hundreds of femtosecond, in good agreement with recent
+experiments. The switching times could be strongly reduced by properly tuning
+the energy gaps between the multiplet energy levels of Cr$^{3+}$. Furthermore,
+the relaxation times also depend on the hybridization of atomic orbitals in the
+first photoexcited state. Our results suggest that the selective manipulation
+of electronic structure by engineering stress-strain or chemical substitution
+allows effective control of the magnetic state switching in photoexcited
+insulating transition-metal oxides.",1705.02439v2
+2017-08-22,ZnO/LSMO Nanocomposites for Energy Harvesting,"The composites of strontium-doped lanthanum manganite (LSMO) with zinc oxide
+(ZnO) are candidate materials for energy harvesting by virtue of their magnetic
+and piezoelectric characteristics. They could be used to harvest energy from
+stray sources, such as the vibrations and electromagnetic noise from
+transformers and compressors within electrical grid power stations to power
+small diagnostic sensors, among other applications. The LSMO/ZnO nanocomposites
+were made by: (i) milling the two bulk powders and, (ii) a wet chemical process
+which resulted in core-shell structures. The electrical, piezoelectric, and
+magnetoelectric properties showed strong dependence on the fabrication method.
+Growth of ZnO nanopillars on the particulate core of LSMO surface appears to
+have improved the piezoelectric properties. Moreover, the chemical bath
+deposition process can be easily modified to incorporate dopants to augment
+these properties further.",1709.01797v1
+2017-09-26,Possibility to realize spin-orbit-induced correlated physics in iridium fluorides,"Recent theoretical predictions of ""unprecedented proximity"" of the electronic
+ground state of iridium fluorides to the SU(2) symmetric $j_{\mathrm{eff}}=1/2$
+limit, relevant for superconductivity in iridates, motivated us to investigate
+their crystal and electronic structure. To this aim, we performed
+high-resolution x-ray powder diffraction, Ir L$_3$-edge resonant inelastic
+x-ray scattering, and quantum chemical calculations on Rb$_2$[IrF$_6$] and
+other iridium fluorides. Our results are consistent with the Mott insulating
+scenario predicted by Birol and Haule [Phys. Rev. Lett. 114, 096403 (2015)],
+but we observe a sizable deviation of the $j_{\mathrm{eff}}=1/2$ state from the
+SU(2) symmetric limit. Interactions beyond the first coordination shell of
+iridium are negligible, hence the iridium fluorides do not show any magnetic
+ordering down to at least 20 K. A larger spin-orbit coupling in iridium
+fluorides compared to oxides is ascribed to a reduction of the degree of
+covalency, with consequences on the possibility to realize spin-orbit-induced
+strongly correlated physics in iridium fluorides.",1709.09027v1
+2017-11-27,Control of surface plasmon-polaritons in magnetoelectric heterostructures,"The work is devoted to the investigation of the surface plasmon polaritons in
+the metal - dielectric heterostructures containing materials with
+magnetoelectric properties. The analysis of various possible configurations
+shows that the magnetoelectric effect influences the plasmonic surface wave
+polarization, localization and dispersion. The essential case of chromium (III)
+oxide as a magnetoelectric dielectric is described in detail, revealing the
+switching between different regimes of magnetoelectric impact on
+plasmon-polaritons. Plasmonic heterostructures with magnetoelectric
+constituents can be used as a polarization- and dispersion-sensitive instrument
+to reveal the magnetoelectric coupling and besides might act as an optical tool
+for control of the surface plasmon-polariton dispersion and dynamics via
+external electric and magnetic fields. Apart from that, the described effects
+can be applied to the manipulation of the far-field optical response of
+plasmonic structures. Composite magnetoelectric materials like
+$\mathrm{BaTiO_3/BiFeO_3}$ that exhibit giant magnetoelectric effect are very
+promising for these purposes.",1711.09606v1
+2018-03-04,Ultrafast optically induced ferromagnetic/anti-ferromagnetic phase transition in GdTiO$_3$ from first principles,"Epitaxial strain and chemical substitution have been the workhorses of
+functional materials design. These static techniques have shown immense success
+in controlling properties in complex oxides through the tuning of subtle
+structural distortions. Recently, an approach based on the excitation of an
+infrared active phonon with intense mid-infrared light has created an
+opportunity for dynamical control of structure through special nonlinear
+coupling to Raman phonons. We use first-principles techniques to show that this
+approach can dynamically induce a magnetic phase transition from the
+ferromagnetic ground state to a hidden antiferromagnetic phase in the rare
+earth titanate GdTiO$_3$ for realistic experimental parameters. We show that a
+combination of a Jahn-Teller distortion, Gd displacement, and infrared phonon
+motion dominate this phase transition with little effect from the octahedral
+rotations, contrary to conventional wisdom.",1803.01323v1
+2018-03-28,Split Fermi Surfaces of the Spin-Orbit-Coupled Metal Cd2Re2O7 Probed by de Haas-van Alphen Effect,"The superconducting pyrochlore oxide Cd2Re2O7 shows a structural transition
+with inversion symmetry breaking (ISB) at Ts1 = 200 K. A recent theory [L. Fu,
+Phys. Rev. Lett. 115, 026401 (2015)] suggests that the origin is an electronic
+instability that leads to a multipolar order in the spin-orbit-coupled metal.
+To observe the Fermi surface of the low-temperature phase of Cd2Re2O7, we
+perform de Haas-van Alphen effect measurements by means of magnetic torque. In
+reference to a calculated band structure, the spin-split Fermi surfaces with
+large cyclotron masses of 5-9m0 are revealed. The splitting is suggested to be
+due to an antisymmetric spin-orbit coupling induced by ISB, the strength of
+which is estimated to be approximately 67 K, which is rather smaller than those
+of typical non-centrosymmetric metals.",1803.10472v1
+2018-06-05,Observation of out-of-plane spin texture in a SrTiO3 (111) two-dimensional electron gas,"We explore the second order bilinear magnetoelectric resistance (BMER) effect
+in the d-electron-based two-dimensional electron gas (2DEG) at the SrTiO3 (111)
+surface. We find an evidence of a spin-split band structure with the archetypal
+spin-momentum locking of the Rashba effect for the in-plane component. Under an
+out-of-plane magnetic field, we find a BMER signal that breaks the six-fold
+symmetry of the electronic dispersion, which is a fingerprint for the presence
+of a momentum dependent out-of-plane spin component. Relativistic electronic
+structure calculations reproduce this spin-texture and indicate that the
+out-of-plane component is a ubiquitous property of oxide 2DEGs arising from
+strong crystal field effects. We further show that the BMER response of the
+SrTiO3 (111) 2DEG is tunable and unexpectedly large.",1806.01533v1
+2018-06-06,Emergent topological spin structures in a centrosymmetric cubic perovskite,"The skyrmion crystal (SkX) characterized by a multiple-q helical spin
+modulation has been reported as a unique topological state that competes with
+the single-q helimagnetic order in non-centrosymmetric materials. Here we
+report the discovery of a rich variety of multiple-q helimagnetic spin
+structures in the centrosymmetric cubic perovskite SrFeO3. On the basis of
+neutron diffraction measurements, we have identified two types of robust
+multiple-q topological spin structures that appear in the absence of external
+magnetic fields: an anisotropic double-q spin spiral and an isotropic
+quadruple-q spiral hosting a three-dimensional lattice of hedgehog
+singularities. The present system not only diversifies the family of SkX host
+materials, but furthermore provides an experimental missing link between
+centrosymmetric lattices and topological helimagnetic order. It also offers
+perspectives for integration of SkXs into oxide electronic devices.",1806.02309v1
+2018-06-08,A superconducting absolute spin valve,"A superconductor with a spin-split excitation spectrum behaves as an ideal
+ferromagnetic spin-injector in a tunneling junction. It was theoretical
+predicted that the combination of two such spin-split superconductors with
+independently tunable magnetizations, may be used as an ideal $absolute$
+spin-valve. Here we report on the first switchable superconducting spin-valve
+based on two EuS/Al bilayers coupled through an aluminum oxide tunnel barrier.
+The spin-valve shows a relative resistance change between the parallel and
+antiparallel configuration of the EuS layers up to 900% that demonstrates a
+highly spin-polarized currents through the junction. Our device may be pivotal
+for realization of thermoelectric radiation detectors, logical element for a
+memory cell in cryogenics superconductor-based computers and superconducting
+spintronics in general.",1806.03151v1
+2018-07-13,"Defect-induced modulation of magnetic, electronic and optical properties of double perovskite oxide La$_2$CoMnO$_6$","Electron- and hole-doped La$_2$CoMnO$_6$(LCMO) are investigated using first
+principles DFT calculations. Hole and electron doping are achieved respectively
+by introducing Sr$^{2+}$ at La$^{3+}$ sites and by inducing O-site vacancies in
+LCMO. Electronic structure calculations suggest that hole doping alters the
+charge and valence state of Co ions, whereas electron doping influences the Mn
+ions. Introduction of defects is found to enhance antisite disorder(ASD) at
+Co/Mn site, which is expected to influence the magnetodielectric properties of
+the system. Our calculations suggest that while ASD and/or hole doping induces
+half-metallicity in LCMO, electron doping restores its insulating state.
+Mean-field calculations performed using exchange constants obtained by mapping
+DFT total energies of different collinear spin configurations onto the Ising
+Hamiltonian find that defects tend to reduce the Curie temperature ($T_C$).
+Interestingly, the calculated linear optical properties of the system suggest
+that the material becomes optically active with high values of birefringence in
+the presence of defects, a property that is highly sought-after in the optical
+communications and laser industry.",1807.05019v2
+2018-07-13,Layered palladates and their relation to nickelates and cuprates,"We explore the layered palladium oxides La$_2$PdO$_4$, LaPdO$_2$ and
+La$_4$Pd$_3$O$_8$ via ab initio calculations. La$_2$PdO$_4$, being low spin
+$d^8$, is quite different from its high spin nickel analog. Hypothetical
+LaPdO$_2$, despite its $d^9$ configuration, has a paramagnetic electronic
+structure very different from cuprates. On the other hand, the hypothetical
+trilayer compound La$_4$Pd$_3$O$_8$ ($d^{8.67}$) is more promising in that its
+paramagnetic electronic structure is very similar to that of overdoped
+cuprates. But even in the $d^9$ limit (achieved by partial substitution of La
+with a 4+ ion), we find that an antiferromagnetic insulating state cannot be
+stabilized due to the less correlated nature of Pd ions. Therefore, this
+material, if it could be synthesized, would provide an ideal platform for
+testing the validity of magnetic theories for high-temperature
+superconductivity.",1807.05046v1
+2018-07-18,"The pyrochlore Ho2Ti2O7: Synthesis, crystal growth and stoichiometry","We have investigated the effect of synthesis and growth conditions on the
+magnetic, structural, and compositional properties of pyrochlore oxide holmium
+titanate and demonstrate a method for growing high quality stoichiometric
+single crystals. A series of polycrystalline samples with various contents of
+Ti (-0.08 \leqslant x \leqslant 0.08, and nominal compositions of Ho2Ti2+xO7)
+were synthesized at different temperatures, and characterized using powder
+X-ray diffraction. The results show that synthesizing powders at a higher
+temperature of 1500 {\deg}C yield single phase compounds. Ti deficient powders
+showed an increase of lattice constant due to stuffing (Ho into Ti positions),
+while Ti rich powders showed a decrease in lattice constant due to
+anti-stuffing (Ti into Ho positions). A post annealing in O2 was found to be
+necessary to accomplish the anti-stuffing process. Use of the conventional
+floating zone (FZ) technique introduced Ti deficiency, stuffing, and oxygen
+vacancies in the grown crystal. Growth of high structural quality and
+stoichiometric single crystals of Ho2Ti2O7 by the traveling solvent floating
+zone (TSFZ) is reported. AC susceptibility measurements revealed that the
+stoichiometric crystal shows a higher ice freezing temperature, indicating that
+crystal quality and stoichiometry play a key role on low temperature spin ice
+properties of this compound.",1807.06788v1
+2018-07-19,Three-Dimensional Quantum Anomalous Hall Effect in Ferromagnetic Insulators,"The quantum anomalous Hall effect (QAHE) hosts the dissipationless chiral
+edge states associated with the nonzero Chern number, providing potentially
+significant applications in future spintronics. The QAHE usually occurs in a
+two-dimensional (2D) system with time-reversal symmetry breaking. In this work,
+we propose that the QAHE can exist in three-dimensional (3D) ferromagnetic
+insulators. By imposing inversion symmetry, we develop the topological
+constraints dictating the appearance of 3D QAHE based on the parity analysis at
+the time-reversal invariant points in reciprocal space. Moreover, using
+first-principles calculations, we identify that 3D QAHE can be realized in a
+family of intrinsic ferromagnetic insulating oxides, including layered and
+non-layered compounds that share a centrosymmetric structure with space group
+$R\bar{3}m$ (No. 166). The Hall conductivity is quantized to be
+$-\frac{3e^2}{hc}$ with the lattice constant $c$ along $c$-axis. The chiral
+surface sheet states are clearly visible and uniquely distributed on the
+surfaces that are parallel to the magnetic moment. Our findings open a
+promising pathway to realize the QAHE in 3D ferromagnetic insulators.",1807.07262v1
+2018-12-20,Magnon-polarons in cubic collinear Antiferromagnets,"We present a theoretical study of excitations formed by hybridization between
+magnons and phonons - magnon-polarons - in antiferromagnets. We first outline a
+general approach to determining which magnon and phonon modes can and cannot
+hybridize in a system thereby addressing the qualitative questions concerning
+magnon-polaron formation. As a specific and experimentally relevant case, we
+study Nickel Oxide quantitatively and find perfect agreement with the
+qualitative analysis, thereby highlighting the strength of the former. We find
+that there are two distinct features of antiferromagnetic magnon-polarons which
+differ from the ferromagnetic ones. First, hybridization between magnons and
+the longitudinal phonon modes is expected in many cubic antiferromagnetic
+structures. Second, we find that the very existence of certain hybridizations
+can be controlled via an external magnetic field, an effect which comes in
+addition to the ability to move the magnon modes relative to the phonons modes.",1812.09239v1
+2019-02-27,High-performance dendritic metamaterial absorber for broadband and near-meter wave radar,"Absorbing materials in ultra-high frequency (UHF) band has constantly been a
+major challenge. The size of the absorber in UHF band is large, whereas the
+resonant frequency band is narrow. According to Rozanov's theory, two kinds of
+composite metamaterial absorbers are designed to realize the requirements of
+low-frequency broadband metamaterial microwave absorber: the
+magnetic-metamaterial composite absorber1 (MA1) and the dielectric-metamaterial
+composite absorber 2 (MA2). In the range of approximately 300-1000MHz, both
+absorbers achieve absorption of over 90% and feature good adaptability to the
+incident angle of the incident wave. The absorbers also present good absorption
+rate of over 80% in the range of 0-45 degree. Processing samples of indium tin
+oxide (ITO) resistance film and polymethacrylimide (PMI) foam board feature
+simple preparation and low cost, and the most important thing is to consider
+the weight problem, which features certain advantages in terms of use.",1902.10398v1
+2019-02-27,Coulomb gap induced by electronic correlation and enlarged superconducting gap in laterally confined Pb islands grown on SrTiO3,"We report high-resolution scanning tunneling microscopy (STM) study of
+nano-sized Pb islands grown on SrTiO3, where three distinct types of gaps with
+different energy scales are revealed. At low temperature, an enlarged
+superconducting gap ({\Delta}s) emerges while there is no enhancement in
+superconducting transition temperature (Tc), giving rise to a larger BCS ratio
+2{\Delta}s/kBTc ~ 6.22. The strong coupling here may originate from the
+electron-phonon coupling on the metal-oxide interface. As the superconducting
+gap is suppressed under applied magnetic field or at elevated temperature,
+Coulomb gap and pseudogap appear, respectively. The Coulomb gap is sensitive to
+the lateral size of Pb islands, indicating that quantum size effect is able to
+influence electronic correlation, which is usually ignored in low-dimensional
+superconductivity. Our experimental results shall shed important light on the
+interplay between quantum size effect and correlations in nano-sized
+superconductors.",1902.10539v1
+2019-03-26,Dynamical Bonding Driving Mixed Valency in a Metal Boride,"Samarium hexaboride is an anomaly, having many exotic and seemingly mutually
+incompatible properties. It was proposed to be a mixed-valent semiconductor,
+and later - a topological Kondo insulator, and yet has a Fermi surface despite
+being an insulator. We propose a new and unified understanding of SmB$_6$
+centered on the hitherto unrecognized dynamical bonding effect: the coexistence
+of two Sm-B bonding modes within SmB$_6$, corresponding to different oxidation
+states of the Sm. The mixed valency arises in SmB$_6$ from thermal population
+of these distinct minima enabled by motion of B. Our model simultaneously
+explains the thermal valence fluctuations, appearance of magnetic Fermi
+surface, excess entropy at low temperatures, pressure-induced phase
+transitions, and related features in Raman spectra and their unexpected
+dependence on temperature and boron isotope.",1903.10650v2
+2019-04-26,Terahertz spin dynamics driven by a field-derivative torque,"Efficient manipulation of magnetization at ultrashort time scales is of
+particular interest for future technology. Here, we numerically investigate the
+influence of the so-called field-derivative torque, which was derived earlier
+based on relativistic Dirac theory [Mondal et al., Phys. Rev. B 94, 144419
+(2016)], on the spin dynamics triggered by ultrashort laser pulses. We find
+that only considering the THz Zeeman field can underestimate the spin
+excitation in antiferromagnetic oxide systems as, e.g., NiO and CoO. However,
+accounting for both, the THz Zeeman torque and the field-derivative torque, the
+amplitude of the spin excitation increases significantly. Studying the damping
+dependence of field-derivative torque we observe larger effects for materials
+having larger damping constants.",1904.11768v2
+2019-04-29,First Observed Metal-like to Insulator Transition in the vacant 3d orbital Quantum Spin Liquid Tb$_2$Ti$_2$O$_7$,"We report the observation of metal-like to insulator transition (MTI) in the
+3dpyrochlore oxide Tb2Ti2O7 at 603 K due to the interaction of empty 3d
+orbitals of Ti4+ with O2- ions, evidenced by the transition in resistivity.
+Magnetisation, specific heat capacity and differential scanning calorimetry
+support the MTI, and the transition is of second order. An appreciable change
+in magnetisation with temperature, without any magnetic phase transition, is a
+behaviour typical in this family of compounds which is seldom observed in empty
+d orbital pyrochlores. The possible mechanism that supports the MTI in Tb2Ti2O7
+is discussed. Subsequently, a broad change in magnetisation from 696 K is also
+seen. Thermogravimetric analysis confirms the observed MTI (603 K) and the
+broad change in magnetisation (696 K)are not due to oxygen vacancy",1904.12478v6
+2019-08-02,Machine-learning-assisted thin-film growth: Bayesian optimization in molecular beam epitaxy of SrRuO3 thin films,"Materials informatics exploiting machine learning techniques, e.g., Bayesian
+optimization (BO), has the potential to offer high-throughput optimization of
+thin-film growth conditions through incremental updates of machine learning
+models in accordance with newly measured data. Here, we demonstrated BO-based
+molecular beam epitaxy (MBE) of SrRuO3, one of the most-intensively studied
+materials in the research field of oxide electronics, mainly owing to its
+unique nature as a ferromagnetic metal. To simplify the intricate search space
+of entangled growth conditions, we ran the BO for a single condition while
+keeping the other conditions fixed. As a result, high-crystalline-quality
+SrRuO3 film exhibiting a high residual resistivity ratio (RRR) of over 50 as
+well as strong perpendicular magnetic anisotropy was developed in only 24 MBE
+growth runs in which the Ru flux rate, growth temperature, and
+O3-nozzle-to-substrate distance were optimized. Our BO-based search method
+provides an efficient experimental design that is not as dependent on the
+experience and skills of individual researchers, and it reduces experimental
+time and cost, which will accelerate materials research.",1908.00739v1
+2019-08-07,Compressive-strain induced enhancement of exchange interactions and short-range magnetic order in Sr$_2$IrO$_4$ investigated by Raman spectroscopy,"We have carried out Raman spectroscopy experiments to investigate two-magnon
+excitations in epitaxial thin films of the quasi-two-dimensional
+antiferromagnetic Mott insulator Sr$_2$IrO$_4$ under in-plane misfit strain.
+With in-plane biaxial compression, the energy of the two-magnon peak increases,
+and the peak remains observable over a wider temperature range above the N\'eel
+temperature, indicating strain-induced enhancement of the superexchange
+interactions between $\it{J}_{eff}$ = 1/2 pseudospins. From density functional
+theory calculations, we have found an increase of the nearest-neighbor hopping
+parameter and exchange interaction with increasing biaxial compressive strain,
+in agreement with the experimental observations. Our experimental and
+theoretical results provide perspectives for systematic, theory-guided strain
+control of the primary exchange interactions in 5$\it{d}$ transition metal
+oxides.",1908.02716v1
+2019-08-18,Influence of chemical stability on the fabrication of MnGa-based devices,"Ferromagnetic films of L10-ordered MnGa have shown promise not only in the
+applications in ultrahigh-density magnetic recording and spintronic memories,
+oscillators, and sensors, but also in controllable studies of novel electrical
+transport phenomena. However, the stability of MnGa in chemicals and oxygen
+plasma that are commonly used in the standard micro-/nano-fabrication process
+has unsettled. In this work, we report a systematic study on the chemical
+stability of the MnGa films in acids, acetone, ethanol, deionized water,
+tetramethylammonium hydroxide (TMAOH) and oxygen plasma. We find that MnGa is
+very stable in acetone and ethanol, while can be attacked substantially if
+soaked in TMAOH solution for sufficiently long time. Deionized water and acids
+(e.g., HCl, H3PO4 and H2SO4 solutions) attack MnGa violently and should be
+avoided whenever possible. In addition, oxygen plasma can passivate the MnGa
+surface by oxidizing the surface. These results provide important information
+for the fabrication and the integration of MnGa based spintronic devices.",1908.06536v1
+2019-08-19,Planar Hall Effect and Anisotropic Magnetoresistance in a polar-polar interface of LaVO$_3$-KTaO$_3$ with strong spin-orbit coupling,"Among the perovskite oxide family, KTaO$_3$ (KTO) has recently attracted
+considerable interest as a possible system for the realization of the Rashba
+effect. In this work, we improvise a novel conducting interface by juxtaposing
+KTO with another insulator, namely LaVO$_3$ (LVO) and report planar Hall effect
+(PHE) and anisotropic magnetoresistance (AMR) measurements. This interface
+exhibits a signature of strong spin-orbit coupling. Our experimental
+observation of two fold AMR at low magnetic fields can be intuitively
+understood using a phenomenological theory for a Rashba spin-split system. At
+high fields ($\sim$8 T), we see a two fold to four fold transition in the AMR
+that could not be explained using only Rashba spin-split energy spectra. We
+speculate that it might be generated through an intricate process arising from
+the interplay between strong spin-orbit coupling, broken inversion symmetery,
+relativistic conduction electron and possible uncompensated localized vanadium
+spins.",1908.06636v1
+2019-08-25,The Critical Current of Disordered Superconductors near T=0,"An increasing current through a superconductor can result in a discontinuous
+increase in the differential resistance at the critical current. This critical
+current is typically associated either with breaking of Cooper-pairs
+(de-pairing) or with a collective motion of vortices (de-pinning). In this work
+we measure superconducting amorphous indium oxide films at low temperatures and
+high magnetic fields. Using heat-balance considerations we demonstrate that the
+current-voltage characteristics are well explained by electron overheating that
+occurs due to the thermal decoupling of the electrons from the host phonons. As
+a result the electrons overheat to a significantly higher temperature than that
+of the lattice. By solving the heat-balance equation we are able to accurately
+predict the critical currents in a variety of experimental conditions. The
+heat-balance approach stems directly from energy conservation. As such it is
+universal and applies to diverse situations from critical currents in
+superconductors to climate bi-stabilities that can initiate another ice-age.
+One disadvantage of the universal nature of this approach is that it is
+insensitive to the microscopic details of the system, which limits our ability
+to draw conclusions regarding the initial departure from equilibrium.",1908.09303v1
+2019-12-01,Designing Disorder into Crystalline Materials,"Crystals are a state of matter characterised by periodic order. Yet
+crystalline materials can harbour disorder in many guises, such as
+non-repeating variations in composition, atom displacements, bonding
+arrangements, molecular orientations, conformations, charge states, orbital
+occupancies, or magnetic structure. Disorder can sometimes be random, but more
+usually it is correlated. Frontier research into disordered crystals now seeks
+to control and exploit the unusual patterns that persist within these
+correlated disordered states in order to access functional responses
+inaccessible to conventional crystals. In this review we survey the core design
+principles at the disposal of materials chemists that allow targeted control
+over correlated disorder. We show how these principles---often informed by
+long-studied statistical mechanical models---can be applied across an
+unexpectedly broad range of materials, including organics, supramolecular
+assemblies, oxide ceramics, and metal--organic frameworks. We conclude with a
+forward-looking discussion of the exciting link to function in responsive
+media, thermoelectrics, topological phases, and information storage.",1912.00366v1
+2019-12-16,Micromagnetic modelling and imaging of vortex|merons structures in an oxide|metal heterostructure,"Using micromagnetic simulations, we have modelled the formation of imprinted
+merons and anti-merons in cobalt overlayers of different thickness (1-8 nm),
+stabilised by interfacial exchange with antiferromagnetic vortices in
+$\alpha$-Fe2O3. Structures similar to those observed experimentally could be
+obtained with reasonable exchange parameters, also in the presence of surface
+roughness. We produce simulated meron|antimeron images by magnetic force
+microscopy (MFM) and nitrogen-vacancy (N-V) centre microscopy, and established
+signatures of these topological structures in different experimental
+configurations.",1912.07511v4
+2019-11-27,The Itinerancy and Interactions of the Linear Strings of Holes in Copper Oxide Superconductors,"Here I present a new model for the itinerancy of the strings of holes in the
+Cuprates HTSC. The model assumes various scenarios with respect to the order of
+the holes hopping and evaluates the weighting parameters for the different
+scenarios. The new model still results in the aggregation of holes into
+strings, but yields a spectral distribution for the itinerancy rates of the
+strings. From this distribution I infer a spectral distribution for the
+magnetic interaction between the strings, which suggests also a spectral
+distribution for the pseudogap parameter, and some relevant experimental
+functions. Apart from these distributions, the basic assumptions of former
+relevant theories remain intact. Such assumptions are the existence of the
+anti-ferromagnetic phases A and B, the basic structure of the pseudogap ground
+state, the excitation operators, and the field. The ground state and the field
+are basically divided into two bands, the gapless low energy band, and the high
+energy band. Due to the wide distributions, the bands may be partially
+overlapped.",1912.11080v1
+2020-03-20,Theoretical investigation of superconductivity in trilayer square-planar nickelates,"The discovery of superconductivity in Sr-doped NdNiO$_{2}$ is a crucial
+breakthrough in the long pursuit for nickel oxide materials with electronic and
+magnetic properties similar to those of the cuprates. NdNiO$_2$ is the
+infinite-layer member of a family of square-planar nickelates with general
+chemical formula R$_{n+1}$Ni$_n$O$_{2n+2}$ (R = La, Pr, Nd, $n= 2, 3, ...
+\infty$). In this letter, we investigate superconductivity in the trilayer
+member of this series (R$_4$Ni$_3$O$_8$) using a combination of
+first-principles and $t-J$ model calculations. R$_4$Ni$_3$O$_8$ compounds
+resemble cuprates more than RNiO$_2$ materials in that only
+Ni-$d_{x^{2}-y^{2}}$ bands cross the Fermi level, they exhibit a largely
+reduced charge transfer energy, and as a consequence superexchange interactions
+are significantly enhanced. We find that the superconducting instability in
+doped R$_4$Ni$_3$O$_8$ compounds is considerably stronger with a maximum gap
+about four times larger than that in Sr$_{0.2}$Nd$_{0.8}$NiO$_2$.",2003.09132v1
+2020-05-09,Quest for New Quantum States via Field-Editing Technology,"We report new quantum states in spin-orbit-coupled single crystals that are
+synthesized using a game-changing technology that ""field-edits"" crystal
+structures (borrowing from the phrase ""genome editing"") via application of
+magnetic field during crystal growth. This study is intended to fundamentally
+address a major challenge facing the research community today: A great deal of
+theoretical work predicting exotic states for strongly spin-orbit-coupled,
+correlated materials has thus far met very limited experimental confirmation.
+These conspicuous discrepancies are due chiefly to the extreme sensitivity of
+these materials to structural distortions. The results presented here
+demonstrate that the ""field-edited"" materials not only are much less distorted
+but also exhibit novel phenomena absent in their ""non-edited"" counterparts. The
+field-edited materials include an array of 4d and 5d transition metal oxides,
+and three representative materials presented here are Ba4Ir3O10, Ca2RuO4, and
+Sr2IrO4. This study provides an entirely new paradigm for discovery of new
+quantum states and materials otherwise unavailable.",2005.04327v3
+2020-05-17,Spin-orbital liquid in Ba$_3$CuSb$_2$O$_9$ stabilized by oxygen holes,"Both the Jahn-Teller distortion of Cu$^{2+}$O$_6$ octahedra and magnetic
+ordering are absent in hexagonal Ba$_3$CuSb$_2$O$_9$ suggesting a Cu 3$d$
+spin-orbital liquid state. Here, by means of resonant x-ray scattering and
+absorption experiment, we show that oxygen 2$p$ holes play crucial role in
+stabilizing this spin-orbital liquid state. These oxygen holes appear due to
+the ""reaction"" Sb$^{5+}$$\rightarrow$Sb$^{3+}$ $+$ two oxygen holes, with these
+holes being able to attach to Cu ions. The hexagonal phase with oxygen 2$p$
+holes exhibits also a novel charge-orbital dynamics which is absent in the
+orthorhombic phase of Ba$_3$CuSb$_2$O$_9$ with Jahn-Teller distortion and Cu
+3$d$ orbital order. The present work opens up a new avenue towards
+spin-charge-orbital entangled liquid state in transition-metal oxides with
+small or negative charge transfer energy.",2005.08200v1
+2020-06-01,Magnetocaloric effect and spin-phonon correlations in RFe0.5Cr0.5O3 (R = Er and Yb) compounds,"We report the results of our investigation of the physical properties of
+mixed metal oxides RFe0.5Cr0.5O3 (R = Er and Yb). ErFe0.5Cr0.5O3 undergoes an
+antiferromagnetic ordering around 270 K followed by spin reorientation (SR)
+transitions around 150 and 8 K respectively. In contrast, in YbFe0.5Cr0.5O3 a
+single SR transition is noted at 36 K, below the AFM ordering temperature of
+280 K. In ErFe0.5Cr0.5O3, a significant value of magnetic entropy change
+({\Delta}SM) ~ -12.4 J/kg-K is noted near the 2nd SR transition, however, this
+value is suppressed in YbFe0.5Cr0.5O3. Temperature dependent dielectric
+permittivity of ErFe0.5Cr0.5O3 and YbFe0.5Cr0.5O3 at different frequencies,
+reveal the presence of Debye-like relaxation behaviour in both compounds, which
+can be due to the effect of charge carrier hopping between localized states of
+Fe and Cr ions. Temperature dependent Raman scattering studies divulge that
+spin-phonon coupling plays a crucial role in defining the physical properties
+of these compounds.",2006.00736v1
+2020-06-24,Microwave response of interacting oxide two-dimensional electron systems,"We present an experimental study on microwave illuminated high mobility
+MgZnO/ZnO based two-dimensional electron systems with different electron
+densities and, hence, varying Coulomb interaction strength. The photoresponse
+of the low-temperature dc resistance in perpendicular magnetic field is
+examined in low and high density samples over a broad range of illumination
+frequencies. In low density samples a response due to cyclotron resonance (CR)
+absorption dominates, while high density samples exhibit pronounced
+microwave-induced resistance oscillations (MIRO). Microwave transmission
+experiments serve as a complementary means of detecting the CR over the entire
+range of electron densities and as a reference for the band mass unrenormalized
+by interactions. Both CR and MIRO-associated features in the resistance permit
+extraction of the effective mass of electrons but yield two distinct values.
+The conventional cyclotron mass representing center-of-mass dynamics exhibits
+no change with density and coincides with the band electron mass of bulk ZnO,
+while MIRO mass reveals a systematic increase with lowering electron density
+consistent with renormalization expected in interacting Fermi liquids.",2006.13627v1
+2020-08-02,Design and analysis of guided modes in photonic waveguides using optical neural network,"We present a deep learning approach using an optical neural network to
+predict the fundamental modal indices $n_{\rm{eff}}$ in a silicon (Si) channel
+waveguide. We use three inputs, e.g., two geometric parameters and one material
+property, and predict the $n_{\rm{eff}}$ for the transverse electric and
+transverse magnetic polarizations. With the least number (i.e., $3^3$ or $4^3$)
+of exact mode solutions from Maxwell's equations, we can uncover the solutions
+which correspond to $10^3$ numerical simulations. Note that this consumes the
+lowest amount of computational resources. The mean squared errors of the exact
+and the predicted results are $<10^{-5}$. Moreover, our parameters' ranges are
+compatible with current photolithography and complementary
+metal-oxide-semiconductor (CMOS) fabrication technology. We also show the
+impacts of different transfer functions and neural network layouts on the
+model's performance. Our approach presents a unique advantage to uncover the
+guided modes in any photonic waveguides within the least possible numerical
+simulations.",2008.00398v1
+2020-09-04,Geometric and Electronic Properties of Li$_2$GeO$_3$,"The 3D ternary Li$_2$GeO$_3$ compound, which could serve as the electrolyte
+material in Li+-based batteries, exhibits an unusual lattice symmetry
+(orthorhombic crystal), band structure, charge density distribution and density
+of states. The essential properties are fully explored through the
+first-principles method. In the delicate calculations and analyses, the main
+features of atom-dominated electronic energy spectrum, space-charge
+distribution, and atom-/orbital-projected density of states are suffi$cient to
+identify the critical multi-orbital hybridizations of the chemical bonds:
+2s-(2p$_x, 2p$_y$, 2p$_z$) and (4s, 4p$_x$, 4p$_y$, 4p$_z$)-(2s, 2p$_x$,
+2p$_y$, 2p$_z$), respectively, for Li-O and Ge-O. This system possesses a large
+indirect gap of Eg = 3.77 eV. There exist a lot of significant covalent bonds,
+with an obvious non-uniformity and anisotropy. In addition, spin-dependent
+magnetic configurations are completely absent. The theoretical framework could
+be developed to investigate the important features of anode and cathode
+materials related to lithium oxide compounds.",2009.02154v1
+2020-09-13,Electric field control of disorder-tunable superconductivity and the emergence of quantum metal at an oxide interface,"We report on an extraordinary field effect of the superconducting
+LaAlO3/KTaO3(111) interface with Tc ~2 K. By applying a gate voltage (VG)
+across KTaO3, the interface can be continuously tuned from superconducting into
+insulating states, yielding a dome-shaped Tc-VG dependence. The electric gating
+has only a minor effect on carrier density as evidenced in the Hall-effect
+measurement, while it changes spatial profile of the carriers in the interface,
+hence the carrier's disorder level significantly. As temperature is decreased,
+the resistance saturates at lowest temperature in both superconducting and
+insulating sides, despite an initial dramatic dropping or increasing, which
+suggests an emergence of quantum metallic state associated with failed
+superconductor and/or fragile insulator. A VG-modulation of the
+magnetic-field-driven superconductor to insulator quantum phase transition
+reveals a non-universal criticality.",2009.05896v1
+2020-09-19,Enhanced Ferromagnetism of CrI3 Bilayer by Self-Intercalation,"Two-dimensional (2D) ferromagnets with high Curie temperature have long been
+the pursuit for electronic and spintronic applications. CrI3 is a rising star
+of intrinsic 2D ferromagnets, however, it suffers from weak exchange coupling.
+Here we propose a general strategy of self-intercalation to achieve enhanced
+ferromagnetism in bilayer CrI3. We showed that filling either Cr or I atoms
+into the van der Waals gap of stacked and twisted CrI3 bilayers can induce the
+double exchange effect and significantly strengthen the interlayer
+ferromagnetic coupling. According to our first-principles calculations, the
+intercalated native atoms act as covalent bridge between two CrI3 layers and
+lead to discrepant oxidation states for the Cr atoms. These theoretical results
+offer a facile route to achieve high-Curie-temperature 2D magnets for device
+implementation.",2009.09212v1
+2021-02-02,"Coupled spin-orbital fluctuations in a three orbital model for $4d$ and $5d$ oxides with electron fillings $n=3,4,5$ -- Application to $\rm NaOsO_3$, $\rm Ca_2RuO_4$, and $\rm Sr_2IrO_4$","A unified approach is presented for investigating coupled spin-orbital
+fluctuations within a realistic three-orbital model for strongly spin-orbit
+coupled systems with electron fillings $n=3,4,5$ in the $t_{2g}$ sector of
+$d_{yz},d_{xz},d_{xy}$ orbitals. A generalized fluctuation propagator is
+constructed which is consistent with the generalized self-consistent
+Hartree-Fock approximation where all Coulomb interaction contributions
+involving orbital diagonal and off-diagonal spin and charge condensates are
+included. Besides the low-energy magnon, intermediate-energy orbiton and
+spin-orbiton, and high-energy spin-orbit exciton modes, the generalized
+spectral function also shows other high-energy excitations such as the Hund's
+coupling induced gapped magnon modes. We relate the characteristic features of
+the coupled spin-orbital excitations to the complex magnetic behavior resulting
+from the interplay between electronic bands, spin-orbit coupling, Coulomb
+interactions, and structural distortion effects, as realized in the compounds
+$\rm NaOsO_3$, $\rm Ca_2RuO_4$, and $\rm Sr_2IrO_4$.",2102.01400v2
+2021-02-04,Spin-orbit-entangled electronic phases in 4$d$ and 5$d$ transition-metal compounds,"Complex oxides with $4d$ and $5d$ transition-metal ions recently emerged as a
+new paradigm in correlated electron physics, due to the interplay between
+spin-orbit coupling and electron interactions. For $4d$ and $5d$ ions, the
+spin-orbit coupling, $\zeta$, can be as large as 0.2-0.4 eV, which is
+comparable with and often exceeds other relevant parameters such as Hund's
+coupling $J_{\rm H}$, noncubic crystal field splitting $\Delta$, and the
+electron hopping amplitude $t$. This gives rise to a variety of
+spin-orbit-entangled degrees of freedom and, crucially, non-trivial
+interactions between them that depend on the $d$-electron configuration, the
+chemical bonding, and the lattice geometry. Exotic electronic phases often
+emerge, including spin-orbit assisted Mott insulators, quantum spin liquids,
+excitonic magnetism, multipolar orderings and correlated topological
+semimetals. This paper provides a selective overview of some of the most
+interesting spin-orbit-entangled phases that arise in $4d$ and $5d$
+transition-metal compounds.",2102.02740v1
+2021-02-12,Probing the evolution of electronic phase-coexistence in complex systems by terahertz radiation,"In complex oxides, the electrons under the influence of competing energetics
+are the cornerstone of coexistence (or phase-separation) of two or more
+electronic/magnetic phases in same structural configuration. Probing of growth
+and evolution of such phase-coexistence state is crucial to determine the
+correct mechanism of related phase-transition. Here, we demonstrate the
+combination of terahertz (THz) time-domain spectroscopy and DC transport as a
+novel strategy to probe the electronic phase-coexistence. This is demonstrated
+in disorder controlled phase-separated rare-earth nickelate thin films which
+exhibit metal-insulator transition in dc conductivity at around 180 K but lack
+this transition in terahertz (THz) dynamics conductivity down to low
+temperature. Such pronounced disparity exploits two extreme attributes: i)
+enormous sensitivity of THz radiation to a spatial range of its
+wavelength-compatible electronic inhomogeneities and ii) insensitivity to a
+range beyond the size of its wavelength. This feature is generic in nature
+(sans a photo-induced effect), depends solely on the size of
+insulating/metallic clusters and formulates a methodology with unique
+sensitivity to investigate electronic phase-coexistence and phase transition of
+any material system.",2102.06353v1
+2021-02-12,Topological surface currents accessed through reversible hydrogenation of the three-dimensional bulk,"Hydrogen, the smallest and most abundant element in nature, can be
+efficiently incorporated within a solid and drastically modify its electronic
+state - it has been known to induce novel magnetoelectric effects in complex
+perovskites and modulate insulator-to-metal transition in a correlated Mott
+oxide. Here we demonstrate that hydrogenation resolves an outstanding challenge
+in chalcogenide classes of three-dimensional (3D) topological insulators and
+magnets - the control of intrinsic bulk conduction that denies access to
+quantum surface transport. With electrons donated by a reversible binding of H+
+ions to Te(Se) chalcogens, carrier densities are easily changed by over 10^20
+cm^-3, allowing tuning the Fermi level into the bulk bandgap to enter
+surface/edge current channels. The hydrogen-tuned topological materials are
+stable at room temperature and tunable disregarding bulk size, opening a
+breadth of platforms for harnessing emergent topological states.",2102.06639v1
+2021-03-08,The fate of compound with AgF$_2$ plus AgO stoichiometry. A theoretical study,"Metal oxyfluorides constitute a broad group of chemical compounds with rich
+spectrum of crystal structures and properties. Here we predict, based on
+evolutionary algorithm approach, the crystal structure and selected properties
+of Ag$_2$OF$_2$. This system may be considered as the 1 to 1 adduct of AgF$_2$
+(i.e. an antiferromagnetic charge transfer positive U insulator) and AgO (i.e.
+a disproportionated negative U insulator). We analyze oxidation states of
+silver in each structure, possible magnetic interactions, as well as energetic
+stability. Prospect is outlined for synthesis of polytypes of interest using
+diverse synthetic approaches.",2103.04733v1
+2021-03-16,Hard x-ray photoemission study on strain effect in LaNiO$_3$ thin films,"The strain effect from a substrate is an important experimental route to
+control electronic and magnetic properties in transition-metal oxide (TMO) thin
+films. Using hard x-ray photoemission spectroscopy, we investigate the strain
+dependence of the valence states in LaNiO$_{3}$ thin films, strongly correlated
+perovskite TMO, grown on four substrates: LaAlO$_{3}$,
+(LaAlO$_{3}$)$_{0.3}$(SrAl$_{0.5}$Ta$_{0.5}$O$_{3}$)$_{0.7}$, SrTiO$_{3}$, and
+DyScO$_{3}$. A Madelung potential analysis of core-level spectra suggests that
+the point-charge description is valid for the La ions while it breaks down for
+Ni and O ions due to a strong covalent bonding between the two. A clear x-ray
+photon-energy dependence of the valence spectra is analyzed by the density
+functional theory, which points to a presence of the La 5$p$ state near the
+Fermi level.",2103.09208v1
+2021-03-19,Entangled radicals may explain lithium effects on hyperactivity,"It is known that bipolar disorder and its lithium treatment involve the
+modulation of oxidative stress. Moreover, it has been observed that lithium's
+effects are isotope-dependent. Based on these findings, here we propose that
+lithium exerts its effects by influencing the recombination dynamics of a
+naturally occurring radical pair involving oxygen. We develop a simple model
+inspired by the radical-pair mechanism in cryptochrome in the context of avian
+magnetoreception and xenon-induced anesthesia. Our model reproduces the
+observed isotopic dependence in the lithium treatment of hyperactivity in rats.
+It predicts a magnetic-field dependence of the effectiveness of lithium, which
+provides one potential experimental test of our hypothesis. Our findings show
+that Nature might harness quantum entanglement for the brain's cognitive
+processes.",2103.11057v1
+2021-05-24,A non-perturbative study of bulk photovoltaic effect enhanced by an optically induced phase transition,"Solid systems with strong correlations and interactions under light
+illumination have the potential for exhibiting interesting bulk photovoltaic
+behavior in the non-perturbative regime, which has remained largely unexplored
+in the past theoretical studies. We investigate the bulk photovoltaic response
+of a perovskite manganite with strongly coupled electron-spin-lattice dynamics,
+using real-time simulations performed with a tight-binding model. The transient
+changes in the band structure and the photoinduced phase transitions, emerging
+from spin and phonon dynamics, result in a nonlinear current versus intensity
+behavior beyond the perturbative limit. The current rises sharply across a
+photoinduced magnetic phase transition, which later saturates at higher light
+intensities due to excited phonon and spin modes. The predicted peak
+photoresponsivity is orders of magnitude higher than other known ferroelectric
+oxides such as BiFeO$_3$. We disentangle phonon-and spin-assisted components to
+the ballistic photocurrent, showing that they are comparable in magnitude. Our
+results illustrate a promising alternative way for controlling and optimizing
+the bulk photovoltaic response through the photoinduced phase transitions in
+strongly-correlated systems.",2105.11310v1
+2021-06-25,Charged Defects and Phonon Hall Effects in Ionic Crystals,"It has been known for decades that a magnetic field can deflect phonons as
+they flow in response to a thermal gradient, producing a thermal Hall effect.
+Several recent experiments have revealed ratios of the phonon Hall conductivity
+to the phonon longitudinal conductivity in oxide dielectrics that are larger
+than $10^{-3}$ when phonon mean-free-paths exceed phonon wavelengths. At the
+same time $\kappa_{H}/\kappa_{L}$ is not strongly temperature dependent. We
+argue that these two properties together imply a mechanism related to phonon
+scattering from defects that break time-reversal symmetry, and we show that
+Lorentz forces acting on charged defects produce substantial skew-scattering
+amplitudes, and related thermal Hall effects that are consistent with recent
+observations.",2106.13889v3
+2021-07-16,First principles studies of the electronic and structural properties of the rutile VO$_{2}$(110) surface and its oxygen-rich terminations,"We present a Density Functional Theory (DFT) study of the structural and
+electronic properties of bare rutile VO$_{2}$(110) surfaces and its oxygen-rich
+terminations. We discuss the performance of various DFT functionals, including
+PBE, PBE+U (U = 2 eV), SCAN and SCAN+rVV functionals with non-magnetic and
+ferromagnetic spin ordering. We predict the presence of a ring-like termination
+that is electronically and structurally related to a V$_{2}$O$_{5}$(001)
+monolayer and shows a higher stability than pure oxygen adsorption phases.
+Despite the fact that the calculated phase stabilities depend on the chosen
+functional, our results show that employing the spin-polarized SCAN functional
+offers a good compromise yielding both a reasonable description of the
+structural and electronic properties of the rutile VO$_{2}$ bulk phase and the
+enthalpy of formation for different stages of vanadium oxidation.",2107.07899v1
+2021-07-22,Variability of electron and hole spin qubits due to interface roughness and charge traps,"Semiconductor spin qubits may show significant device-to-device variability
+in the presence of spin-orbit coupling mechanisms. Interface roughness, charge
+traps, layout or process inhomogeneities indeed shape the real space wave
+functions, hence the spin properties. It is, therefore, important to understand
+how reproducible the qubits can be, in order to assess strategies to cope with
+variability, and to set constraints on the quality of materials and
+fabrication. Here we model the variability of single qubit properties (Larmor
+and Rabi frequencies) due to disorder at the Si/SiO$_2$ interface (roughness,
+charge traps) in metal-oxide-semiconductor devices. We consider both electron
+qubits (with synthetic spin-orbit coupling fields created by micro-magnets) and
+hole qubits (with intrinsic spin-orbit coupling). We show that charge traps are
+much more limiting than interface roughness, and can scatter Rabi frequencies
+over one order of magnitude. We discuss the implications for the design of spin
+qubits and for the choice of materials.",2107.10902v2
+2021-09-01,On the resistance minimum in LaAlO$_3$/Eu$_{1-x}$La$_x$TiO$_3$/SrTiO$_3$ heterostructures,"In this paper we study LaAlO$_3$/Eu$_{1-x}$La$_x$TiO$_3$/SrTiO$_3$ structures
+with nominally x = 0, 0.1 and different thicknesses of the
+Eu$_{1-x}$La$_x$TiO$_3$ layer. We observe that both systems have many
+properties similar to previously studied LaAlO$_3$/EuTiO$_3$/SrTiO$_3$ and
+other oxide interfaces, such as the formation of a 2D electron liquid for 1 or
+2 unit cells of Eu$_{1-x}$La$_x$TiO$_3$; a metal-insulator transition driven by
+the thickness increase of Eu$_{1-x}$La$_x$TiO$_3$ layer; the presence of an
+Anomalous Hall effect (AHE) when driving the systems above the Lifshitz point
+with a backgate voltage; and a minimum in the temperature dependence of the
+sheet resistance below the Lifshitz point in the one-band regime, which becomes
+more pronounced with increasing gate voltage. However, and notwithstanding the
+likely presence of magnetism in the system, we do not attribute that minimum to
+the Kondo effect, but rather to the properties of SrTiO$_3$ crystal and the
+inevitable effects of charge trapping when using back gates.",2109.00620v1
+2021-10-04,Experimental observation of pseudogap in a modulation-doped Mott insulator: Sn/Si(111)-($\sqrt{3}\times \sqrt{3}$)-R30$^\textrm{o}$,"Unusual quantum phenomena usually emerge upon doping Mott insulators. Using a
+combinatorial molecular beam epitaxy system integrated with cryogenic scanning
+tunneling microscopy, we investigate the electronic structure of a
+modulation-doped Mott insulator Sn/Si(111)-($\sqrt{3}\times
+\sqrt{3}$)-R30$^\textrm{o}$. In underdoped regions, we observe a universal
+pseudogap opening around the Fermi level, which changes little with the applied
+magnetic field and the occurrence of Sn vacancies. The pseudogap gets smeared
+out at elevated temperatures and alters in size with the spatial confinement of
+the Mott insulating phase. Our findings, along with the previously observed
+superconductivity at a higher doping level, are highly reminiscent of the
+electronic phase diagram in the doped copper oxide compounds.",2110.01136v1
+2021-10-19,Effect of the electronic charge gap on LO bond-stretching phonons in undoped La$_2$CuO$_4$ calculated using LDA+U,"Typical density-functional theory calculations that wrongly predict undoped
+cuprates to be metallic also predict Cu-O half- and full-breathing phonon
+energies that are significantly softer than observed, presumably because of
+weak on-site Coulomb repulsion on the Cu 3d orbitals. We used DFT+U
+calculations with antiferromagnetic supercells of La$_2$CuO$_4$ to establish
+correlation between the on-site repulsion strength, tuned via adjusting the
+value of U, and phonon dispersions. We find that breathing and half-breathing
+phonons reach experimental values when U is tuned to obtain the correct optical
+gap and magnetic moments. We demonstrate that using distorted supercells within
+DFT+U is a promising framework to model phonons in undoped cuprates and other
+perovskite oxides with complex, interrelated structural and electronic degrees
+of freedom.",2110.10274v2
+2022-01-04,Energy dissipation in composites with hybrid nacre-like helicoidal microstructures,"Natural ceramic composites present complex microstructures that lead to
+tortuous crack paths and confer them high toughness. Current microreinforced
+composites do not yet reach the same level of complexity in their
+microstructures, resulting in poorer properties. To achieve complex
+microstructuration, magnetically-assisted slip casting (MASC) was conducted
+using a setup with 4 degrees of freedom. Among all possible microstructures, a
+hybrid design between nacre-like and helicoidal arrangements was selected due
+to its ability to tilt and twist the crack path. The hybrid microstructured
+specimen fabricated, consisting of aluminum oxide micro platelets in a silicone
+matrix, were tested under compression and their mechanical performance
+compared. Although nacre-like composites exhibited the highest strength and
+toughness, helicoidal hybrids could show some ductility and higher stiffness.
+The fabrication strategy proposed here could thus be a simple route to study
+more complex microstructures in view of increasing the toughness of
+microplatelet reinforced composites.",2201.04955v1
+2022-01-26,High precision scalable power converter for accelerator magnets,"The lower conduction power losses and the positive temperature coefficient
+that favours parallel connections, make Silicon Carbide (SiC) metal oxide
+semiconductor field-effect transistors (MOSFETs) to be an excellent replacement
+of existing Silicon insulated gate bipolar transistors (IGBTs) technology.
+These characteristics combined with high switching frequency operation, enables
+the design of high-accuracy DC-DC converters with minimised filtering
+requirements. This paper investigates the design for a converter with
+high-accuracy current (0.9ppm) supplying a 0.05H electromagnetic load, aiming
+to achieve the accuracy without the use of active filters, by using SiC MOSFETs
+and a scalable module-based converter design.",2201.10824v2
+2022-02-09,Gate tunable anomalous Hall effect at (111) LaAlO$_3$/SrTiO$_3$ interface,"We present the theoretical prediction of a gate tunable anomalous Hall effect
+(AHE) in an oxide interface as a hallmark of spin-orbit coupling. The observed
+AHE at low-temperatures in the presence of an external magnetic field emerges
+from a complex structure of the Berry curvature of the electrons on the Fermi
+surface and strongly depends on the orbital character of the occupied bands. A
+detailed picture of the results comes from a multiband low-energy model with a
+generalized Rashba interaction that supports characteristic out-of-plane spin
+and orbital textures. We discuss strategies for optimizing the intrinsic AHE in
+(111) SrTiO$_3$ heterostructure interfaces.",2202.04664v1
+2022-04-07,Where to find lossless metals?,"Hypothetical metals having optical absorption losses as low as those of the
+transparent insulators, if found, could revolutionize optoelectronics. We
+perform the first high-throughput search for lossless metals among all known
+inorganic materials in the databases of over 100,000 entries. The 381
+candidates are identified -- having well-isolated partially-filled bands -- and
+are analyzed by defining the figures of merit and classifying their real-space
+conductive connectivity. The existing experimental evidence of most candidates
+being insulating, instead of conducting, is due to the limitation of current
+density functional theory in predicting narrow-band metals that are unstable
+against magnetism, structural distortion, or electron-electron interactions. We
+propose future research directions including conductive oxides, intercalating
+layered materials, and compressing these false-metal candidates under high
+pressures into eventual lossless metals.",2204.03222v2
+2022-04-12,First-principles electronic structure investigation of HgBa$_{2}$Ca$_{n-1}$Cu$_{n}$O$_{2n+2+x}$ with the SCAN density functional,"We perform first-principles calculation to study the electronic structure of
+HgBa$_{2}$Ca$_{n-1}$Cu$_{n}$O$_{2n+2+x}$ copper oxides up to $n = 6$ for the
+undoped parent compound $(x = 0)$ and up to $n = 3$ for the doped compound $(x
+> 0)$ by means of the SCAN meta-GGA density functional. Our calculations
+predict an antiferromagnetic insulator ground state for the parent compounds
+with an energy gap that decreases with the number of CuO$_{2}$ planes. We
+report structural, electronic and magnetic order evolution with $x$ which agree
+with experiments. We find an enhanced density of states at Fermi level at $x
+\approx 0.25$ for the single-layered compound manifesting in a peak of the
+Sommerfeld parameter, which recently has been discussed as a possible signature
+of quantum criticality generic to all cuprates.",2204.05719v3
+2022-05-09,Coupling Spin Defects in Hexagonal Boron Nitride to Titanium Oxide Ring Resonators,"Spin-dependent optical transitions are attractive for a plethora of
+applications in quantum technologies. Here we report on utilization of high
+quality ring resonators fabricated from TiO2 to enhance the emission from
+negatively charged boron vacancies in hexagonal Boron Nitride. We show that the
+emission from these defects can efficiently couple into the whispering gallery
+modes of the ring resonators. Optically coupled boron vacancy showed
+photoluminescence contrast in optically detected magnetic resonance signals
+from the hybrid coupled devices. Our results demonstrate a practical method for
+integration of spin defects in 2D materials with dielectric resonators which is
+a promising platform for quantum technologies.",2205.04031v1
+2022-06-30,Current Mapping of Amorphous LaAlO3/SrTiO3 near the Metal-Insulator Transition,"The two-dimensional electron system found between LaAlO3 and SrTiO3 hosts a
+variety of physical phenomena that can be tuned through external stimuli. This
+allows for electronic devices controlling magnetism, spin-orbit coupling, and
+superconductivity. Controlling the electron density by varying donor
+concentrations and using electrostatic gating are convenient handles to modify
+the electronic properties, but the impact on the microscopic scale,
+particularly of the former, remains underexplored. Here, we image the current
+distribution at 4.2 K in amorphous-LaAlO3/SrTiO3 using scanning
+superconducting-quantum-interference-device microscopy while changing the
+carrier density in situ using electrostatic gating and oxygen annealing. We
+show how potential disorder affects the current and how homogeneous 2D flow
+evolves into several parallel conducting channels when approaching the
+metal-to-insulator transition. We link this to ferroelastic domains and oxygen
+vacancies. This has important consequences for micro- and nanoscale devices
+with low carrier density and fundamental studies on quantum effects in oxides.",2206.15458v1
+2022-07-07,Asymmetric Ground States in La$_{0.67}$Sr$_{0.33}$MnO$_3$/BaTiO$_3$ heterostructures Induced by Flexoelectric Bending,"Misfit strain delivered from single-crystal substrates typically modifies the
+ground states of transition metal oxides, generating increasing interests in
+designing modern transducers and sensors. Here, we demonstrate that
+magnetotransport properties of La$_{0.67}$Sr$_{0.33}$MnO$_3$ (LSMO) films were
+continuously tuned by uniaxial strain produced by a home-designed bending jig.
+The electrical conductivity and Curie temperature of LSMO films are enhanced by
+bending stresses. The resistivity of a u-shape bended LSMO decays three times
+faster than that of a n-shape bended LSMO as a response to the same magnitude
+of strain. The asymmetric magnetic states in uniaxially strained LSMO are
+attributed to the dual actions of Jahn-Teller distortion and strain gradient
+mediated flexoelectric fields in an adjacent ferroelectric layer. These
+findings of multi-field regulation in a single material provide a feasible
+means for developing flexible electronic and spintronic devices.",2207.03297v1
+2022-07-13,Strong Spin-Orbit Torque Induced by the Intrinsic Spin Hall Effect in Cr1-xPtx,"We report on a spin-orbit torque study of the spin current generation in
+Cr1-xPtx alloy, using the light 3d ferromagnetic Co as the spin current
+detector. We find that the dampinglike spin-orbit torque of Cr1-xPtx/Co
+bilayers can be enhanced by tuning the Cr concentration in the Cr1-xPtx layer,
+with a maximal value of 0.31 at the optimal composition of Cr0.2Pt0.8. We find
+that the spin current generation in the Cr1-xPtx alloy can be fully understood
+by the characteristic trade-off between the intrinsic spin Hall conductivity of
+Pt and the carrier lifetime in the dirty limit. We find no evidence for the
+spin current generation by other mechanisms in this material, revealing that
+the role of Cr is found to be simply the same as other metals and oxides in
+previous studies. This work also establishes the low-resistivity Cr0.2Pt0.8 as
+an energy-efficient spin-orbit torque provider for magnetic memory and
+computing technologies.",2207.05992v2
+2022-07-21,New CuSO4-related high-temperature polymorph of AgIISO4,"Silver(II) compounds exhibit powerful oxidizing properties and strong
+magnetic superexchange. AgSO4 is a rare fluorine-free salt of Ag(II) which
+found some application in organic chemistry. Here, we report a discovery of a
+new AgSO4 polymorph (\b{eta}). The distinct nature of the two polytypes of
+AgSO4 is established using powder x-ray diffraction, vibrational spectroscopy
+and theoretical calculations. The \b{eta} polymorph crystallizes in the
+monoclinic system (P21/n) and shows structural similarities with CuSO4. DFT
+calculations indicate very small differences in the energy of the two
+polymorphs AgSO4, but the relative stability of the \b{eta} polymorph should
+increase with temperature. The monoclinic distortion of the orthorhombic CuSO4
+prototype originates from an unprecedented strong antiferromagnetic interaction
+between Ag sites along the unit cell diagonal.",2207.10393v1
+2022-07-23,Coexistence of Weyl semimetal and Weyl nodal loop semimetal phases in a collinear antiferromagnet,"Antiferromagnets (AFMs) with anomalous quantum responses have lead to new
+progress for the understanding of their magnetic and electronic structures from
+symmetry and topology points of view. Two typical topological states are the
+collinear antiferromagnetic Weyl semimetal (WSM) and Weyl nodal loop semimetal
+(WNLSM). In comparison with the counterparts in ferromagnets and non-collinear
+AFMs, the WSMs and WNLSMs in collinear AFMs are still waiting for experimental
+verification. In this work, we theoretically predicted the coexistence of Weyl
+points (WPs) and Weyl nodal loops (WNLs) in transition metal oxide RuO2. Owing
+to the small magnetocrystalline anisotropy energy, the WPs and WNLs can
+transform to each other via tuning the Neel vector. Moreover, since the WPs are
+very close to Fermi level and the WNLs are even crossing Fermi level, the
+topological states in RuO2 can be easily probed by photoemission and STM
+methods. Our result provides a promising material platform for the study of WSM
+and WNLSM states in collinear AFMs.",2207.11472v1
+2022-07-29,Structural investigation of Ayurveda Lauha (Iron) Bhasma,"In Ayurveda, Lauha (Iron) bhasma is primarily used to cure diseases related
+with iron deficiency in humans. It is produced from purified raw metallic iron
+using a combination of multi-step traditional preparation processes described
+in the Ayurveda literature. Here, we present results of structural
+investigation performed on the medicinal grade Lauha bhasma using various X-ray
+based techniques. Our results indicate that after several rounds of heating and
+cooling in specific conditions following the Ayurvedic preparation procedure,
+metallic iron eventually converts to a natural iron-oxide mineral belonging to
+the Magnetite group. Scanning electron microscopy (SEM) and X-ray standing wave
+assisted fluorescence measurements carried out on powdered bhasma specimen
+reveal that the Magnetite micro-particles in the bhasma specimen are usually
+present in the form of agglomerates of nano-particles. We anticipate that the
+Ayurvedic Lauha Bhasma has great potential for noninvasive localized target
+killing of cancer cells, particularly in sensitive parts of the human body such
+as brain, spinal cord, and lungs, via necrosis by application of an alternating
+external magnetic field or photo electron generation through X-rays.",2207.14615v3
+2022-08-09,Effect of annealing in the formation of well crystallized and textured SrFe$_{12}$O$_{19}$ films grown by RF magnetron sputtering,"We have studied the influence of annealing treatment on the crystalline
+growth of SrFe_12_O_19 previously deposited on Si (100) substrates using radio
+frequency (RF) magnetron sputtering. For this goal, two grown films, with and
+without \textit{ex-situ} heating step, have been analysed and compared to
+determine the differences in their structural, compositional and magnetic
+properties. The results obtained by the different analysis techniques, in
+particular M\""ossbauer spectroscopy together with EXAFS and XANES data, suggest
+that the as-grown film is composed of nanocrystalline maghemite nanoparticles
+and amorphous strontium oxide. A strontium hexaferrite canonical structure with
+c-axis orientation in the sample plane was found for the annealed film.",2208.04658v1
+2022-09-06,Preserving Metamagnetism in Self-Assembled FeRh Nanomagnets,"We present self-assembly routes of metamagnetic FeRh nanoisland arrays using
+sputter deposition processing. Controlling the growth parameters and epitaxy
+allows tuning the size and shape of the FeRh nanoislands. While the phase
+transition between antiferromagnetic and ferromagnetic order is largely
+suppressed in nanoislands formed on oxide substrates via thermodynamic
+nucleation, we find that metamagnetism is largely preserved in nanomagnet
+arrays formed through solid-state dewetting. This behavior is strongly
+dependent on the resulting crystal faceting of the nanoislands, which is
+characteristic of each assembly route. Comparing the calculated surface
+energies for each magnetic phase of the nanoislands reveals that metamagnetism
+can be suppressed or allowed by specific geometrical configurations of the
+facets. Furthermore, we find that the spatial confinement leads to very
+pronounced supercooling and the absence of phase separation in the nanoislands.
+Finally, the supported nanomagnets are chemically etched away from the
+substrates to inspect the phase transition properties of self-standing
+nanoparticles. We demonstrate that solid-state dewetting is a feasible and
+scalable way to obtain supported and free-standing FeRh nanomagnets with
+preserved metamagnetism.",2209.02469v1
+2022-10-19,Near-Field Optical MIMO Communication with Polarization-dependent Metasurfaces,"The ability to control waves at the nanoscale has attracted considerable
+attention to ultrathin metasurface lenses (metalenses) in optical imaging and
+encryption systems. We propose an approach to active tuning metasurfaces by
+integrating an ultrathin layer of indium-tin-oxide (ITO) into a unit cell as an
+electro-optically tunable material. A proposed design features two orthogonal
+wings that can independently manipulate waves with corresponding orthogonal
+polarizations. The charge carrier concentration in the ITO accumulation layer
+is altered by modulating the applied bias voltage. This bias voltage generates
+phase variations at terahertz frequencies for the reflected transverse electric
+and transverse magnetic polarized waves. It is possible to move both focal
+points of a metalens without any physical movement by varying the bias voltage.
+In addition, this paper explores the application of virtually moving metalens
+for a novel multiple-input and multiple-output (MIMO) communication
+architecture. We demonstrate a communication system based on single-point
+binary data communication and hexadecimal orbital angular momentum (OAM) data
+communication. Then, orthogonal channels can be used for MIMO communication
+with high capacity. The proposed design paves the way for high-speed
+communications as well as polarization-controlled molecular imaging systems.",2210.10237v1
+2022-12-05,Room temperature multiferroicity in a transition metal dichalcogenide,"The coexistence of multiple ferroic orders, i.e. multiferroicity, is a scarce
+property to be found in materials. Historically, this state has been found
+mainly in 3-dimensional complex oxides, but so far this state has still been
+elusive for the most widely studied and characterized family of 2-dimensional
+compounds, the transition metal dichalcogenides. In this study we report the
+experimental realization of multiferroic states in this family of materials, at
+room temperature, in bulk single crystals of Te-doped WSe2. We observe the
+coexistence of ferromagnetism and ferroelectricity, evidenced in the presence
+of magnetization and piezoresponse force microscopy hysteresis loops. These
+findings open the possibility of widening the use and study of van der
+Waals-based multifunctional devices for new nanoelectronics and spintronics
+applications.",2212.02490v2
+2022-12-22,Tunneling anisotropic spin galvanic effect,"We show that pure spin injection from a magnetic electrode into an inversion
+symmetry-broken system composed of a tunnel barrier and a metallic region
+generates a transverse charge current. Such a tunnelling spin galvanic
+conversion is robust to disorder and non-local, i.e. injection and detection
+contacts do not coincide, and is strongly anisotropic whenever the internal
+spin-orbit field has a non-trivial angular dependence. The anisotropy shows up
+in linear response, contrary to what happens in bulk conversion setups lacking
+tunnelling elements. This is particularly relevant for spin-charge conversion
+at oxide interfaces, where both the tunnel barrier and the receiving
+low-dimensional metallic system host effective spin-orbit fields with complex
+angular symmetries.",2212.11698v2
+2023-01-21,Replica theory for disorder-free spin-lattice glass transition on a tree-like simplex network,"A class of pyrochlore oxides, $A_2$Mo$_2$O$_7$ ($A =$ Ho, Y, Dy, Tb) with
+magnetic ions on corner-sharing tetrahedra is known to exhibit spin-glass
+transitions without appreciable amount of quenched disorder. Recently a
+disorder-free theoretical model for such a system has been proposed which takes
+into account not only spins but also lattice distortions as dynamical variables
+[K. Mitsumoto, C. Hotta and H. Yoshino, Phys. Rev. Lett. 124, 087201 (2020)].
+In the present paper we develop and analyze an exactly solvable disorder-free
+mean-field model which is a higher-dimensional counterpart of the model. We
+find the system exhibit complex free-energy landscape accompanying replica
+symmetry breaking through the spin-lattice coupling.",2301.08884v1
+2023-01-26,Unraveling the effects of inter-site Hubbard interactions in spinel Li-ion cathode materials,"Accurate first-principles predictions of the structural, electronic,
+magnetic, and electrochemical properties of cathode materials can be key in the
+design of novel efficient Li-ion batteries. Spinel-type cathode materials
+Li$_x$Mn$_2$O$_4$ and Li$_x$Mn$_{1.5}$Ni$_{0.5}$O$_4$ are promising candidates
+for Li-ion battery technologies, but they present serious challenges when it
+comes to their first-principles modeling. Here, we use density-functional
+theory with extended Hubbard functionals - DFT+$U$+$V$ with on-site $U$ and
+inter-site $V$ Hubbard interactions - to study the properties of these
+transition-metal oxides. The Hubbard parameters are computed from
+first-principles using density-functional perturbation theory. We show that
+while $U$ is crucial to obtain the right trends in properties of these
+materials, $V$ is essential for a quantitative description of the structural
+and electronic properties, as well as the Li-intercalation voltages. This work
+paves the way for reliable first-principles studies of other families of
+cathode materials without relying on empirical fitting or calibration
+procedures.",2301.11143v2
+2023-02-03,Ligand hole driven metal-insulator transition in a prototypical transition metal double perovskite oxide Ca$_2$FeMnO$_6$,"Ca$_2$FeMnO$_6$ (CFMO) double perovskite was studied using first principles
+density functional theory and tight-binding (TB) Hamiltonian modeling using
+extended Hubbard model. We have shown by electronic structure analysis that
+charge- and magnetic-ordering are driven by charge disproportionation at low
+temperature caused by partial localization of O-$2p$ ligand holes at alternate
+Fe sites that creates Jahn-Teller distortion, which leads to metal to insulator
+transition (MIT) in CFMO. Our results suggests MIT was triggered by negative
+charge-transfer energy of self-hole doping, responsible for symmetry lowering
+transitions. Notably, the band-gap was found to fundamentally controlled by the
+strength of the charge-transfer energy, and not by the Mott-Hubbard
+interactions, which can be modeled by composition, pressure or stoichiometry
+modulations. The fundamental insights presented in this work will help
+understand similar physics and mechanisms in other class of perovskites and
+correlated metals.",2302.01545v2
+2023-02-13,Thickness and temperature dependent damping in La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ epitaxial films,"The damping of La0.67Sr0.33MnO3 (LSMO) epitaxial films as a function of
+thickness at different temperatures was studied. The competition between two
+scattering types (\r{ho}-like and {\sigma}-like) with entirely distinct
+thickness and temperature dependencies resulted in complicated damping
+behavior. The behavior of {\sigma}-like damping in LSMO films is consistent
+with the behavior in magnetic metal films. However, because \r{ho}-like damping
+is sensitive to the fine electron structure near the Fermi surface, the
+distortion of the oxygen octahedra controlled by the film thickness is an
+important factor in controlling the damping. Our study demonstrates that the
+complexity of damping in LSMO epitaxial films is a consequence of
+strong-correlation effects, which are characteristic of complex
+transition-metal oxides.",2302.06099v3
+2023-03-05,Real-Space Observation of Ligand Hole State in Cubic Perovskite SrFeO$_3$,"An anomalously high valence state sometimes shows up in transition-metal
+oxide compounds. In such systems, holes tend to occupy mainly the ligand $p$
+orbitals, giving rise to interesting physical properties such as
+superconductivity in cuprates and rich magnetic phases in ferrates. However, no
+one has ever observed the distribution of ligand holes in real space. Here, we
+report a successful observation of the spatial distribution of valence
+electrons in cubic perovskite SrFeO$_3$ by high-energy X-ray diffraction
+experiments and precise electron density analysis using a core differential
+Fourier synthesis method. A real-space picture of ligand holes formed by the
+orbital hybridization of Fe 3$d$ and O 2$p$ is revealed. The anomalous valence
+state in Fe is attributed to the considerable contribution of the ligand hole,
+which is related to the metallic nature and the absence of Jahn-Teller
+distortions in this system.",2303.02571v2
+2023-03-20,Thermal decomposition of the Kitaev material $α$-RuCl$_3$ and its influence on low-temperature behavior,"We explore the effect of heat treatment in argon atmosphere under various
+temperatures up to $500^\circ$C on single crystals of $\alpha$-RuCl$_3$ by
+study of the mass loss, microprobe energy dispersive x-ray spectroscopy, powder
+x-ray diffraction, electrical resistance as well as low-temperature magnetic
+susceptibility and specific heat. Clear signatures of dechlorination and
+oxidation of Ru appear for annealing temperatures beyond $300^\circ$C. Analysis
+of the specific heat below 2~K reveals a RuO$_2$ mass fraction of order $1\%$
+for pristine $\alpha$-RuCl$_3$ which increases up to $20\%$ after thermal
+annealing, fully consistent with mass-loss analysis. The small RuO$_2$
+inclusions drastically reduce the global electrical resistance and may thus
+significantly affect low-temperature thermal transport and Hall effect.",2303.11308v1
+2023-03-24,Simulation of 1/f charge noise affecting a quantum dot in a Si/SiGe structure,"Due to presence of magnetic field gradient needed for coherent spin control,
+dephasing of single-electron spin qubits in silicon quantum dots is often
+dominated by $1/f$ charge noise. We investigate theoretically fluctuations of
+ground state energy of an electron in gated quantum dot in realistic Si/SiGe
+structure. We assume that the charge noise is caused by motion of charges
+trapped at the semiconductor-oxide interface. We consider a realistic range of
+trapped charge densities, $\rho \! \sim \! 10^{10}$ cm$^{-2}$, and typical
+lenghtscales of isotropically distributed displacements of these charges,
+$\delta r \! \leq \! 1$ nm, and identify pairs $(\rho,\delta r)$ for which the
+amplitude and shape of the noise spectrum is in good agreement with spectra
+reconstructed in recent experiments on similar structures.",2303.13968v1
+2023-04-20,Noncollinear DFT+$U$ and Hubbard parameters with fully-relativistic ultrasoft pseudopotentials,"The magnetic, noncollinear parametrization of Dudarev's DFT+$U$ method is
+generalized to fully-relativistic ultrasoft pseudopotentials. We present the
+definition of the DFT+$U$ total energy functional, and the calculation of
+forces and stresses in the case of orthogonalized atomic orbitals defining the
+localised Hubbard manifold, where additional contributions arising from the
+derivative of the inverse square root of the overlap matrix appear. We further
+extend the perturbative calculation of the Hubbard $U$ parameters within
+density-functional perturbation theory to the noncollinear relativistic case,
+by exploiting an existing and recently developed theoretical approach that
+takes advantage of the time-reversal operator to solve a second Sternheimer
+equation. We validate and apply the new scheme by studying the electronic
+structure and the thermodynamics of the binary compounds EuX (where X = O, S,
+Se, Te is a chalcogen atom), as representative simple crystals, and of the
+pyrochlore Cd$_2$Os$_2$O$_7$, representative of a more structurally complex
+oxide.",2304.10178v1
+2023-04-29,Natural orbitals and two-particle correlators as tools for analysis of effective exchange couplings in solids,"Using generalizations of natural orbitals, spin-averaged natural orbitals,
+and two-particle charge correlators for solids, we investigate electronic
+structure of antiferromagnetic transition-metal oxides with a fully
+self-consistent, finite-temperature GW method. Our findings disagree with
+Goodenough-Kanamori (GK) rules, commonly used for qualitative interpretation of
+such solids. First, we found a strong dependence of natural orbital occupancies
+on momenta contradicting GK assumptions. Second, along the momentum path, the
+character of natural orbitals changes. In particular, contributions of oxygen
+2s orbitals are important, which has not been considered in the GK rules. To
+analyze the influence of electronic correlation on the values of effective
+exchange coupling constants, we use both natural orbitals and two-particle
+correlators and show that electronic screening modulates the degree of
+superexchange by stabilizing the charge-transfer contributions, greatly
+affecting these coupling constants. Finally, we give a set of predictions and
+recommendations regarding the use of density functional, Green's function, and
+wave-function methods for evaluating effective magnetic couplings in molecules
+and solids.",2305.00325v1
+2023-05-04,Two-particle bound states on a lattice,"Two-particle lattice states are important for physics of magnetism,
+superconducting oxides, and cold quantum gases. The quantum-mechanical lattice
+problem is exactly solvable for finite-range interaction potentials. A two-body
+Schroedinder equation can be reduced to a system of linear equations whose
+numbers scale with the number of interacting sites. For the simplest cases such
+as on-site or nearest-neighbor attractions, many pair properties can be derived
+analytically, although final expressions can be quite complicated. In this
+work, we systematically investigate bound pairs in one-, two-, and
+three-dimensional lattices. We derive pairing conditions, plot phase diagrams,
+and compute effective masses, radii, and energies. Along the way, we analyze
+nontrivial physical effects such as light pairs and the dependence of binding
+thresholds on pair momenta. At the end, we discuss the preformed-pair mechanism
+of superconductivity and stability of many-pair systems against phase
+separation. The paper is a combination of original work and pedagogical
+tutorial.",2305.02548v2
+2023-05-10,Correlations of spin splitting and orbital fluctuations due to 1/f charge noise in the Si/SiGe Quantum Dot,"Fluctuations of electric fields can change the position of a gate-defined
+quantum dot in a semiconductor heterostructure. In the presence of magnetic
+field gradient, these stochastic shifts of electron's wavefunction lead to
+fluctuations of electron's spin splitting. The resulting spin dephasing due to
+charge noise limits the coherence times of spin qubits in isotopically purified
+Si/SiGe quantum dots. We investigate the spin splitting noise caused by such
+process caused by microscopic motion of charges at the semiconductor-oxide
+interface. We compare effects of isotropic and planar displacement of the
+charges, and estimate their densities and typical displacement magnitudes that
+can reproduce experimentally observed spin splitting noise spectra. We predict
+that for defect density of $10^{10}$ cm$^{-2}$, visible correlations between
+noises in spin splitting and in energy of electron's ground state in the
+quantum dot, are expected.",2305.06011v1
+2023-05-25,Optimizing Experimental Parameters for Orbital Mapping,"A new material characterization technique is emerging for the transmission
+electron microscope (TEM). Using electron energy-loss spectroscopy, real space
+mappings of the underlying electronic transitions in the sample, so called
+orbital maps, can be produced. Thus, unprecedented insight into the electronic
+orbitals responsible for most of the electrical, magnetic and optical
+properties of bulk materials can be gained. However, the incredibly demanding
+requirements on spatial as well as spectral resolution paired with the low
+signal-to-noise ratio severely limits the day-to-day use of this new technique.
+With the use of simulations, we strive to alleviate these challenges as much as
+possible by identifying optimal experimental parameters. In this manner, we
+investigate representative examples of a transition metal oxide, a material
+consisting entirely of light elements, and an interface between two different
+materials to find and compare acceptable ranges for sample thickness,
+acceleration voltage and electron dose for a scanning probe as well as for
+parallel illumination.",2305.16039v1
+2023-05-25,A tunable and versatile 28nm FD-SOI crossbar output circuit for low power analog SNN inference with eNVM synapses,"In this work we report a study and a co-design methodology of an analog SNN
+crossbar output circuit designed in a 28nm FD-SOI technology node that
+comprises a tunable current attenuator and a leak-integrate and fire neurons
+that would enable the integration of emerging non-volatile memories (eNVMs) for
+synaptic arrays based on various technologies including phase change (PCRAM),
+oxide-based (OxRAM), spin transfer and spin orbit torque magnetic memories
+(STT, SOT-MRAM). Circuit SPICE simulation results and eNVM experimental data
+are used to showcase and estimate the neurons fan-in for each type of eNVM
+considering the technology constraints and design trade-offs that set its
+limits such as membrane capacitance and supply voltage, etc.",2305.16187v1
+2023-05-29,Essential L-Amino Acid-Functionalized Graphene Oxide for Liquid Crystalline Phase Formation,"The colloidal 2D materials based on graphene and its modifications are of
+great interest when it comes to forming LC phases. These LC phases allow
+controlling the orientational order of colloidal particles, paving the way for
+the efficient processing of modified graphene with anisotropic properties.
+Here, we present the peculiarities of AA functionalization of GO, along with
+the formation of its LC phase and orientational behavior in an external
+magnetic field. We discuss the influence of pH on the GOLC, ultimately showing
+its pH-dependent behavior for GO-AA complexes. In addition, we observe
+different GO morphology changes due to the presence of AA functional groups,
+namely L-cysteine dimerization on the GO platform. The pH dependency of
+AA-functionalized LC phase of GO is examined for the first time. We believe
+that our studies will open new possibilities for applications in
+bionanotechnologies due to self-assembling properties of LCs and magnificent
+properties of GO.",2305.17919v1
+2023-06-08,Hidden Hydroxides in KOH-Grown BaNiO3 Crystals: A Potential Link to Their Catalytic Behavior,"The hexagonal perovskite BaNiO3, prepared via non-ceramic approaches, is
+known to act as a good catalyst for the oxygen-evolution reaction (OER) in
+alkaline media. Here we report our observation that BaNiO3 synthesized via KOH
+flux growth and high O2 pressure ceramic synthesis have different magnetic
+properties. We show that this is because the KOH flux-grown crystals made in
+open-air are actually a hydroxide-containing form of BaNiO3 that can be dried
+upon annealing in O2 flow. This work not only unveils a previously unknown
+aspect of the BaNiO3 OER catalyst and offers some insights into the underlying
+mechanism, but also suggests that hydroxide ions may be present in other
+hexagonal perovskite oxides prepared in wet conditions.",2306.05488v2
+2023-07-03,"Strain, Young's modulus, and structural transition of EuTiO3 thin films probed by micro-mechanical methods","EuTiO3 (ETO) is a well-known complex oxide mainly investigated for its
+magnetic properties and its incipient ferro-electricity. In this work, we
+demonstrate the realization of suspended micro-mechanical structures, such as
+cantilevers and micro-bridges, from 100 nm-thick single-crystal epitaxial ETO
+films deposited on top of SrTiO3(100) substrates. By combining profile analysis
+and resonance frequency measurements of these devices, we obtain the Young's
+modulus, strain, and strain gradients of the ETO thin films. Moreover, we
+investigate the ETO anti-ferro-distorsive transition by temperature-dependent
+characterizations, which show a non-monotonic and hysteretic mechanical
+response. Comparison between experimental and literature data allows us to
+weight the contribution from thermal expansion and softening to the tuning
+slope, while a full understanding of the origin of such a wide hysteresis is
+still missing. We also discuss the influence of oxygen vacancies on the
+reported mechanical properties by comparing stoichiometric and oxygen-deficient
+samples.",2307.01022v2
+2023-09-24,Tuning the Néel temperature in an antiferromagnet: the case of NixCo1-xO microstructures,"We show that it is possible to tune the N\'eel temperature of
+nickel(II)-cobalt(II) oxide films by changing the Ni to Co ratio. We grow
+single crystalline micrometric triangular islands with tens of nanometers
+thickness on a Ru(0001) substrate using high temperature oxygen-assisted
+molecular beam epitaxy. Composition is controlled by adjusting the deposition
+rates of Co and Ni. The morphology, shape, crystal structure and composition
+are determined by low-energy electron microscopy and diffraction, and
+synchrotron-based x-ray absorption spectromicroscopy. The antiferromagnetic
+order is observed by x-ray magnetic linear dichroism. Antiferromagnetic domains
+up to micrometer width are observed.",2309.13721v1
+2023-09-28,Full Breit Hamiltonian in the Multiwavelets Framework,"New techniques in core-electron spectroscopy are necessary to resolve the
+structures of oxides of $f$-elements and other strongly correlated materials
+that are present only as powders and not as single crystals. Thus, accurate
+quantum chemical methods need to be developed to calculate core spectroscopic
+properties in such materials. In this contribution, we present an important
+development in this direction, extending our fully adaptive real-space
+multiwavelet basis framework to tackle the 4-component Dirac-Coulomb-Breit
+Hamiltonian. We show that Multiwavelets are able to reproduce one-dimensional
+grid-based approaches. They are however a fully three-dimensional approach
+which can later on be extended to molecules and materials. Our Multiwavelet
+implementation attained precise results irrespective of the chosen nuclear
+model, provided that the error threshold is tight enough and the chosen
+polynomial basis is sufficiently large. Furthermore, our results confirmed that
+in two-electron species, the magnetic and Gauge contributions from $s$-orbitals
+are identical in magnitude and can account for the experimental evidence from
+$K$ and $L$ edges.",2309.16183v2
+2023-10-09,Isolation of Single Donors in ZnO,"The shallow donor in zinc oxide (ZnO) is a promising semiconductor spin qubit
+with optical access. Single indium donors are isolated in a commercial ZnO
+substrate using plasma focused ion beam (PFIB) milling. Quantum emitters are
+identified optically by spatial and frequency filtering. The indium donor
+assignment is based on the optical bound exciton transition energy and magnetic
+dependence. The single donor emission is intensity and frequency stable with a
+transition linewidth less than twice the lifetime limit. The isolation of
+optically stable single donors post-FIB fabrication is promising for optical
+device integration required for scalable quantum technologies based on single
+donors in direct band gap semiconductors.",2310.05806v3
+2023-10-16,First-Principle Investigation Of Near-Field Energy Transfer Between Localized Quantum Emitters in Solids,"We present a predictive and general approach to investigate near-field energy
+transfer processes between localized defects in semiconductors, which couples
+first principle electronic structure calculations and a nonrelativistic quantum
+electrodynamics description of photons in the weak-coupling regime. We apply
+our approach to investigate an exemplar point defect in an oxide, the F center
+in MgO, and we show that the energy transfer from a magnetic source, e.g., a
+rare earth impurity, to the vacancy can lead to spin non conserving long-lived
+excitation that are dominant processes in the near field, at distances relevant
+to the design of photonic devices and ultra-high dense memories. We also define
+a descriptor for coherent energy transfer to predict geometrical configurations
+of emitters to enable long-lived excitations, that are useful to design optical
+memories in semiconductor and insulators.",2310.10028v1
+2023-10-27,Nanostructured Superconductors,"The relevant length scales for superconductivity are of the order of
+nanometers. By confining the superconducting condensate to such dimensions,
+many physical properties change substantially, and novel phenomena emerge,
+which are absent in the pristine material. We discuss various methods of
+creating artificial nanostructures by top-down approaches in metallic and
+copper-oxide superconductors and their applications. Such nanostructures can be
+used to control magnetic flux quanta in superconductors, anchoring them to
+engineered defects to avoid dissipation, guiding their motion, or building
+artificial flux-quanta arrangements. Nanopatterned superconductors are
+essential for creating model systems for basic research and enable building
+almost dissipationless and ultrafast electronic devices and highly sensitive
+sensors.",2310.18232v1
+2023-11-01,A complementary experimental study of epitaxial La0.67Sr0.33MnO3 to identify morphological and chemical disorder,"Gaining insight into the characteristics of epitaxial complex oxide films is
+essential to control the behavior of devices and catalytic processes. It is
+known that substrate induced strain, doping, and layer growth can affect the
+electronic and magnetic properties of the film's bulk. In this study, we
+demonstrate a clear distinction between the bulk and surface of thin films of
+La0.67Sr0.33MnO3 in terms of chemical composition, electronic disorder, and
+surface morphology. We employed a combined experimental approach of X-ray based
+characterization methods and scanning probe microscopy. X-ray diffraction and
+resonant X-ray reflectivity revealed surface non-stochiometry in the strontium
+and lanthanum, as well as an accumulation of oxygen vacancies. Scanning
+tunneling microscopy showed a staggered growth surface morphology accompanied
+by an electronic phase separation (EPS) related to this non-stochiometry. The
+EPS is likely responsible for the temperature-dependent resistivity transition
+and is a cause of a proposed mixed-phase ferromagnetic and paramagnetic state
+near room temperature in these thin films.",2311.00504v1
+2023-11-08,Mie-scattering controlled all-dielectric resonator-antenna for bright and directional point dipole emission,"Designing a deterministic, bright, robust, room temperature stable, on-demand
+solid-state single photon source has been a major demand in the field of
+quantum-photonics. For this, various single-photon resonator and antenna
+schemes are being actively explored. Here, using the Cartesian multi-polar
+decomposition of the excited Mie-scattering moments, we present the design of a
+all-dielectric coupled-dipolar antenna comprising of two dielectric (Tin-oxide,
+TiO$_2$) cylinders sandwiching a nanodiamond based nitrogen-vacancy (NV$^-$)
+center trapped in a poly-vinyl alcohol (PVA) matrix. The Mie-scattering
+resonant cavity formed in the middle PVA layer provides more than an order of
+magnitude decay rate or Purcell enhancement. The balancing of the electric and
+magnetic dipolar moments (a phenomenon commonly known as the Kerker condition)
+of the coupled TiO$_2$ cylinders under NV$^-$ dipole excitation, provides
+significant directionality to the radiation pattern. Using a collection lens
+with a numerical aperture (NA) of 0.9 the vertical collection efficiency (VCE)
+was observed to be around 80\% at the NV$^-$ center's zero-phonon line
+wavelength.",2311.04500v2
+2023-11-12,Quantum Griffiths singularity in three-dimensional superconductor to Anderson critical insulator transition,"Disorder is ubiquitous in real materials and can have dramatic effects on
+quantum phase transitions. Originating from the disorder enhanced quantum
+fluctuation, quantum Griffiths singularity (QGS) has been revealed as a
+universal phenomenon in quantum criticality of low-dimensional superconductors.
+However, due to the weak fluctuation effect, QGS is very challenging to detect
+experimentally in three-dimensional (3D) superconducting systems. Here we
+report the discovery of QGS associated with the quantum phase transition from
+3D superconductor to Anderson critical insulator in a spinel oxide MgTi2O4
+(MTO). Under both perpendicular and parallel magnetic field, the dynamical
+critical exponent diverges when approaching the quantum critical point,
+demonstrating the existence of 3D QGS. Among 3D superconductors, MTO shows
+relatively strong fluctuation effect featured as a wide superconducting
+transition region. The enhanced fluctuation, which may arise from the mobility
+edge of Anderson localization, finally leads to the occurrence of 3D quantum
+phase transition and QGS. Our findings offer a new perspective to understand
+quantum phase transitions in strongly disordered 3D systems.",2311.06710v1
+2023-12-06,Surface termination effect of SrTiO3 substrate on ultrathin SrRuO3,"A uniform one-unit-cell-high step on the SrTiO3 substrate is a prerequisite
+for growing high-quality epitaxial oxide heterostructures. However, it is
+inevitable that defects induced by mixed substrate surface termination exist at
+the interface, significantly impacting the properties of ultrathin films. In
+this study, we microscopically identify the origin for the lateral
+inhomogeneity in the growth of ultrathin SrRuO3 films due to the step effects
+of SrTiO3(001). By using atomic-resolved scanning transmission electron
+microscopy, we observe two distinct types of step propagation along the [011]
+and [0-11]crystallographic direction in SrTiO3-SrRuO3 heterostructures,
+respectively. In particular, the type-II [0-11] step results in lateral
+discontinuity of monolayer SrRuO3 and originates from the SrO-terminated
+regions along the TiO2-terminated step edge. Such an induced lateral
+discontinuity should be responsible for the distinct electronic and magnetic
+properties of monolayer SrRuO3. Our findings underscore the critical importance
+of using single termination STO substrate to achieve high-quality termination
+selective films and to unveil the intrinsic properties of epitaxial films in
+the atomic limit.",2312.14944v1
+2024-01-04,Emergent transverse-field Ising model in $\boldsymbol{d}^\mathbf{4}$ spin-orbit Mott insulators,"Mott-insulating transition metal oxides containing $t_{2g}^4$ ions with
+strong spin-orbit coupling were recently demonstrated to display unusual
+magnetism due to a dynamical mixing of the low-energy multiplet states via
+exchange processes. Here we derive exchange interactions in the situation where
+a tetragonal or trigonal crystal field selects a single relevant excited state
+on top of the singlet ionic ground state, producing an effective
+spin-$\frac12$. We show that these moments universally obey antiferromagnetic
+transverse-field Ising model (TFIM) with an intrinsic transverse field
+generated by the splitting of the two ionic singlets. Using Ru$^{4+}$ as a
+example ion, we provide quantitative estimates of the exchange and illustrate
+the emergent TFIM physics based on phase diagrams and excitation spectra
+obtained for several 2D lattices - square, honeycomb, as well as for the
+frustrated triangular lattice.",2401.02532v1
+2024-02-03,Reducing disorder in PbTe nanowires for Majorana research,"Material challenges are the key issue in Majorana nanowires where surface
+disorder constrains device performance. Here, we tackle this challenge by
+embedding PbTe nanowires within a latticematched crystal, an oxide-free
+environment. The wire edges are shaped by self-organized growth instead of
+lithography, resulting in nearly-atomic-flat facets along both cross-sectional
+and longitudinal directions. Quantized conductance plateaus are observed at
+zero magnetic field with channel lengths reaching 1.54 $\mu$m, significantly
+surpassing the state-of-the-art of III-V nanowires (nearly an
+order-of-magnitude improvement compared to InSb). Coupling PbTe to a Pb film
+unveils a flat interface spanning microns and a large superconducting gap of 1
+meV. Our results meet the stringent low-disorder requirement for the definitive
+observation of Majoranas.",2402.02132v1
+2024-03-07,Pressure tuning of hydrogen bond ordering in the metal-organic framework [(CH3)2NH2]Mn(HCOO)3,"The influence of pressure on the hydrogen bond ordering in the perovskite
+metal-organic framework [(CH3)2NH2]Mn(HCOO)3 has been investigated by
+dielectric, pyroelectric adn magnetic measurements in a piston-cylinder cell.
+Under ambient pressure the ordering of hydrogen bonds takes place at TC = 188 K
+and induces a first-order ferroelectric phase transition. With increasing
+pressure to p = 3.92 kbar, the order-disorder transition shifts to a lower
+temperature and retains the first-order ferroelectric nature. However, under
+higher pressures, the ordering process of hydrogen bonds is split into two
+transitions: a broad antiferroelectric transition at high temperature and a
+first-order ferroelectric transition at low temperature. With increasing
+pressure, the antiferroelectric phase is enhanced whereas the ferroelectric
+phase is greatly suppressed, which implies that compression of the perovskite
+framework favors antiparallel arrangement of the hydrogen bonds. The canted
+anti-ferromagnetic transition was almost unchanged when pressure up to 10.85
+kbar. Our study demonstrated that the perovskite metal-organic frameworks are
+more sensitive to external pressure than conventional perovskite oxides so that
+their electric properties can be easily tuned by pressure.",2403.04241v1
+2024-04-08,Vortex matching at 6 T in YBa$_2$Cu$_3$O$_{7-δ}$ thin films by imprinting a 20 nm-periodic pinning array with a focused helium ion beam,"Controlled engineering of vortex pinning sites in copper-oxide
+superconductors is a critical issue in manufacturing devices based on magnetic
+flux quanta. To address this, we employed a focused He-ion beam (He-FIB) to
+irradiate thin YBa$_2$Cu$_3$O$_{7-\delta}$ films and create ultradense
+hexagonal arrays of defects with lattice spacings as small as 20 nm. Critical
+current and magnetoresistance measurements demonstrate efficient pinning by an
+unprecedentedly high matching field of 6 T visible in a huge temperature range
+from the critical temperature $T_c$ down to 2 K. These results show that He-FIB
+irradiation provides excellent opportunities for the development and
+application of superconducting fluxonic devices based on Abrikosov vortices. In
+particular, our findings suggest that such devices can operate at temperatures
+far below $T_c$, where superconductivity is robust.",2404.05382v1
+1999-06-03,Transition to Long Range Magnetic Order in the Highly Frustrated Insulating Pyrochlore Antiferromagnet Gd_2Ti_2O_7,"Experimental evidence from measurements of the a.c. and d.c. susceptibility,
+and heat capacity data show that the pyrochlore structure oxide, Gd_2Ti_2O_7,
+exhibits short range order that starts developing at 30K, as well as long range
+magnetic order at $T\sim 1$K. The Curie-Weiss temperature, $\theta_{CW}$ =
+-9.6K, is largely due to exchange interactions. Deviations from the Curie-Weiss
+law occur below $\sim$10K while magnetic heat capacity contributions are found
+at temperatures above 20K. A sharp maximum in the heat capacity at $T_c=0.97$K
+signals a transition to a long range ordered state, with the magnetic specific
+accounting for only $\sim$ 50% of the magnetic entropy. The heat capacity above
+the phase transition can be modeled by assuming that a distribution of random
+fields acts on the $^8S_{7/2}$ ground state for Gd$^{3+}$. There is no
+frequency dependence to the a.c. susceptibility in either the short range or
+long range ordered regimes, hence suggesting the absence of any spin-glassy
+behavior. Mean field theoretical calculations show that no long range ordered
+ground state exists for the conditions of nearest-neighbor antiferromagnetic
+exchange and long range dipolar couplings. At the mean-field level, long range
+order at various commensurate or incommensurate wave vectors is found only upon
+inclusion of exchange interactions beyond nearest-neighbor exchange and dipolar
+coupling. The properties of Gd$_2Ti_2O_7 are compared with other geometrically
+frustrated antiferromagnets such as the Gd_3Ga_5O_{12} gadolinium gallium
+garnet, RE_2Ti_2O_7 pyrochlores where RE = Tb, Ho and Tm, and Heisenberg-type
+pyrochlore such as Y_2Mo_2O_7, Tb_2Mo_2O_7, and spinels such as ZnFe_2O_4",9906043v1
+2004-05-18,Structural and magnetic properties of the single-layer manganese oxide La{1-x}Sr{1+x}MnO4,"Using x-ray and neutron scattering, we have studied the structural and
+magnetic properties of the single-layer manganite La{1-x}Sr{1+x}MnO4 (0 < x <
+0.7). Single crystals were grown by the traveling-solvent floating-zone method
+at 18 La/Sr concentrations. The low-temperature phase diagram can be understood
+by considering the strong coupling of the magnetic and orbital degrees of
+freedom, and it can be divided into three distinct regions: low (x < 0.12),
+intermediate (0.12< x < 0.45), and high (x > 0.45) doping. LaSrMnO_4 (x=0) is
+an antiferromagnetic Mott insulator,and its spin-wave spectrum is
+well-described by linear spin-wave theory for the spin-2 square-lattice
+Heisenberg Hamiltonian with Ising anisotropy. Upon doping, as the e_g electron
+concentration (1-x) decreases, both the two-dimensional antiferromagnetic spin
+correlations in the paramagnetic phase and the low-temperature ordered moment
+decrease due to an increase of frustrating interactions, and Neel order
+disappears above xc = 0.115(10). In the intermediate region, there exists
+neither long-range magnetic nor superstructural order. Short-range-correlated
+structural ""nanopatches"" begin to form above x ~ 0.25. At high doping (x >
+0.45), the ground state of La{1-x}Sr{1+x}MnO4 exhibits long-range
+superstructural order and a complex (CE-type) antiferromagnetic order which
+differs from that at low doping. The superstructural order is thought to arise
+from charge and orbital ordering on the Mn sites. For x > 0.50, the
+superstructural order becomes incommensurate with the lattice, with a
+modulation wavevector that depends linearly on the e_g electron concentration.
+On the other hand, the magnetic order remains commensurate, but loses its
+long-range coherence upon doping beyond x = 0.50.",0405424v1
+2008-08-27,Epitaxial Zn(x)Fe(3-x)O(4) Thin Films: A Spintronic Material with Tunable Electrical and Magnetic Properties,"The ferrimagnetic spinel oxide Zn(x)Fe(3-x)O(4) combines high Curie
+temperature and spin polarization with tunable electrical and magnetic
+properties, making it a promising functional material for spintronic devices.
+We have grown epitaxial thin films with 0<=x<=0.9 on MgO(001) substrates with
+excellent structural properties both in pure Ar atmosphere and an Ar/O2 mixture
+by laser molecular beam epitaxy. We find that the electrical conductivity and
+the saturation magnetization can be tuned over a wide range during growth. Our
+extensive characterization of the films provides a clear picture of the
+underlying physics of this spinel ferrimagnet with antiparallel Fe moments on
+the A and B sublattice: (i) Zn substitution removes both Fe3+ moments from the
+A sublattice and itinerant charge carriers from the B sublattice, (ii) growth
+in finite oxygen partial pressure generates Fe vacancies on the B sublattice
+also removing itinerant charge carriers, and (iii) application of both Zn
+substitution and excess oxygen results in a compensation effect as Zn
+substitution partially removes the Fe vacancies. A decrease (increase) of
+charge carrier density results in a weakening (strengthening) of double
+exchange and thereby a decrease (increase) of conductivity and the saturation
+magnetization. This scenario is confirmed by the observation that the
+saturation magnetization scales with the longitudinal conductivity. The
+combination of tailored films with semiconductor materials such as ZnO in
+multi-functional heterostructures seems to be particularly appealing.",0808.3642v3
+2010-09-05,Cell death induced by the application of alternating magnetic fields to nanoparticle-loaded dendritic cells,"In this work, the capability of primary, monocyte-derived dendritic cells
+(DCs) to uptake iron oxide magnetic nanoparticles (MNPs) is assessed and a
+strategy to induce selective cell death in these MNP-loaded DCs using external
+alternating magnetic fields (AMFs) is reported. No significant decrease in the
+cell viability of MNP-loaded DCs, compared to the control samples, was observed
+after five days of culture. The amount of MNPs incorporated into the cytoplasm
+was measured by magnetometry, which confirmed that 1 to 5 pg of the particles
+were uploaded per cell. The intracellular distribution of these MNPs, assessed
+by transmission electron microscopy, was found to be primarily inside the
+endosomic structures. These cells were then subjected to an AMF for 30 min, and
+the viability of the blank DCs (i.e., without MNPs), which were used as control
+samples, remained essentially unaffected. However, a remarkable decrease of
+viability from approximately 90% to 2-5% of DCs previously loaded with MNPs was
+observed after the same 30 min exposure to an AMF. The same results were
+obtained using MNPs having either positive (NH2+) or negative (COOH-) surface
+functional groups. In spite of the massive cell death induced by application of
+AMF to MNP-loaded DCs, the amount of incorporated magnetic particles did not
+raise the temperature of the cell culture. Clear morphological changes at the
+cell structure after magnetic field application were observed using scanning
+electron microscopy. Therefore, local damage produced by the MNPs could be the
+main mechanism for the selective cell death of MNP-loaded DCs under an AMF.
+Based on the ability of these cells to evade the reticuloendothelial system,
+these complexes combined with an AMF should be considered as a potentially
+powerful tool for tumour therapy.",1009.0907v2
+2013-12-04,Structure and Properties of α-NaFeO2-type Ternary Sodium Iridates,"The synthesis, structure, and elementary magnetic and electronic properties
+are reported for layered compounds of the type Na3-xMIr2O6 and Na3-xM2IrO6,
+where M is a transition metal from the 3d series (M=Zn, Cu, Ni, Co, Fe and Mn).
+The rhombohedral structures, in space group R-3m, were determined by refinement
+of neutron and synchrotron powder diffraction data. No clear evidence for long
+range 2:1 or 1:2 honeycomb-like M/Ir ordering was found in the neutron powder
+diffraction patterns except in the case of M = Zn, thus in general the
+compounds are best designated as sodium deficient {\alpha}-NaFeO2-type phases
+with formulas Na1-xM1/3Ir2/3O2 or Na1-xM2/3Ir1/3O2. Synchrotron powder
+diffraction patterns indicate that several of the compounds likely have
+honeycomb in-plane metal-iridium ordering with disordered stacking of the
+layers. All the compounds are sodium deficient under our synthetic conditions
+and are black and insulating. Weiss constants derived from magnetic
+susceptibility measurements indicate that Na0.62Mn0.61Ir0.39O2,
+Na0.80Fe2/3Ir1/3O2, Na0.92Ni1/3Ir2/3O2, Na0.86Cu1/3Ir2/3O2, and
+Na0.89Zn1/3Ir2/3O2 display dominant antiferromagnetic interactions. For
+Na0.90Co1/3Ir2/3O2 the dominant magnetic interactions at low temperature are
+ferromagnetic while at high temperatures they are antiferromagnetic; there is
+also a change in the effective moment. Low temperature specific heat
+measurements (to 2 K) on Na0.92Ni1/3Ir2/3O2 indicate the presence of a broad
+magnetic ordering transition. X-ray absorption spectroscopy shows that iridium
+is at or close to the 4+ oxidation state in all compounds. 23Na nuclear
+magnetic resonance measurements comparing Na2IrO3 to Na0.92Ni1/3Ir2/3O2 and
+Na0.89Zn1/3Ir2/3O2 provide strong indications that the electron spins are
+short-range ordered in the latter two materials. All of the compounds are spin
+glasses.",1312.0995v1
+2018-02-12,"Superconducting transition temperatures in the electronic and magnetic phase diagrams of Sr2VFeAsO3-delta, a superconductor","We elucidate the magnetic phases and superconducting transition temperatures
+(Tc) in Sr2VFeAsO3-delta (21113V), an iron-based superconductor with a
+thick-blocking layer fabricated from a perovskite-related transition metal
+oxide. At low temperatures (T < 37.1 K), 21113V exhibited a superconducting
+phase in the range 0.031 =< delta =< 0.145 and an antiferromagnetic (AFM) iron
+sublattice in the range 0.267 =< delta =< 0.664. Mixed-valent vanadium
+exhibited a dominant AFM phase in 0.031 =< delta =< 0.088, and a partial
+ferrimagnetic (Ferri.) phase in the range 0.124 =< delta =< 0.664. The Ferri.
+phase was the most dominant at a delta value of 0.267, showing an AFM phase of
+Fe at T < 20 K. Increasing the spontaneous magnetic moments reduced the
+magnetic shielding volume fraction due to the superconducting phase. This
+result was attributed to the magnetic phase of vanadium, which dominates the
+superconductivity of Fe in 21113V. The Tc-delta curve showed two maxima. The
+smaller and larger of Tc maxima occurred at delta = 0.073 and delta = 0.145,
+respectively; the latter resides on the phase boundary between AFM and the
+partial Ferri. phases of vanadium. 21113V is a useful platform for verifing new
+mechanisms of Tc enhancement in iron-based superconductors.",1802.03907v2
+2016-08-28,Magnetic order and spin-orbit coupled Mott state in double perovskite (La$_{1-x}$Sr$_x$)$_2$CuIrO$_6$,"Double-perovskite oxides that contain both 3d and 5d transition metal
+elements have attracted growing interest as they provide a model system to
+study the interplay of strong electron interaction and large spin-orbit
+coupling (SOC). Here, we report on experimental and theoretical studies of the
+magnetic and electronic properties of double-perovskites
+(La$_{1-x}$Sr$_x$)$_2$CuIrO$_6$ ($x$ = 0.0, 0.1, 0.2, and 0.3). The undoped
+La$_2$CuIrO$_6$ undergoes a magnetic phase transition from paramagnetism to
+antiferromagnetism at T$_N$ $\sim$ 74 K and exhibits a weak ferromagnetic
+behavior below $T_C$ $\sim$ 52 K. Two-dimensional magnetism that was observed
+in many other Cu-based double-perovskites is absent in our samples, which may
+be due to the existence of weak Cu-Ir exchange interaction. First-principle
+density-functional theory (DFT) calculations show canted antiferromagnetic
+(AFM) order in both Cu$^{2+}$ and Ir$^{4+}$ sublattices, which gives rise to
+weak ferromagnetism. Electronic structure calculations suggest that
+La$_2$CuIrO$_6$ is an SOC-driven Mott insulator with an energy gap of $\sim$
+0.3 eV. Sr-doping decreases the magnetic ordering temperatures ($T_N$ and
+$T_C$) and suppresses the electrical resistivity. The high temperatures
+resistivity can be fitted using a variable-range-hopping model, consistent with
+the existence of disorders in these double-pervoskite compounds.",1608.07763v2
+2019-06-04,Influence of interface and microstructure on magnetization of epitaxial Fe4N thin film,"Epitaxial Fe4N thin films grown on lattice-matched LaAlO3 (LAO) substrate
+using sputtering and molecular beam epitaxy techniques have been studied in
+this work. Within the sputtering process, films were grown with conventional
+direct current magnetron sputtering (dcMS) and for the first time, using a high
+power impulse magnetron sputtering (HiPIMS) process. Surface morphology and
+depth profile reveal that HiPIMS deposited film has the lowest roughness, the
+highest packing density and the sharpest interface. La from the LAO substrate
+and Fe from the film interdiffuse and forms an undesired interface spreading to
+an extent of about 10-20 nm. In the HiPIMS process, layer by layer type growth
+leads to a globular microstructure which restricts the extent of the
+interdiffused interface. Such substrate-film interactions and microstructure
+play a vital role in affecting the electronic hybridization and magnetic
+properties of Fe4N films. The magnetic moment (Ms) was compared using bulk,
+element-specific and magnetic depth profiling techniques. We found that Ms was
+the highest when the thickness of the interdiffused layer was lowest and only
+be achieved in the HiPIMS grown samples. Presence of small moment at the N site
+was also evidenced by element-specific x-ray circular dichroism measurement in
+HiPIMS grown sample. A large variation in the Ms values of Fe4N found in the
+experimental works carried out so far could be due to such interdiffused layer
+which is generally not expected to form in otherwise stable oxide substrate. In
+addition, a consequence of substrate-film interdiffusion and microstructure
+results in different kinds of different kind of magnetic anisotropies in films
+grown using different techniques.",1906.01238v1
+2019-10-01,"Oxygen deficiency and migration mediated electric polarization in Fe,Co-substituted SrTiO$_{3-δ}$","We use density functional theory (DFT) calculations to show that oxygen
+vacancies ($v_\mathrm{O}$) and mobility induce noncentrosymmetric polar
+structures in SrTi$_{1-x-y}$Fe$_{x}$Co$_{y}$O$_{3-\delta}$ ($x=y=0.125$) with
+$\delta = \{0.125, 0.25\}$, enhance the saturation magnetization and give rise
+to large changes in the electric polarization $\vert\Delta P\vert$. We present
+an intuitive set of rules for SrTiFeCoO$_{3-\delta}$ (STFC), which are based on
+the interplay between (Co/Fe)-$v_\mathrm{O}$ defects, magnetic cations
+coordination and topological vacancy disorder. STFC structures convey layered
+crystals with sheets of linear organized O$_{4,5,6}$-coordinated Fe-Co pairs,
+sandwiched with layers of O$_{5}$-coordinated Ti. Co,Fe-$v_\mathrm{O}$ defects
+are the source of the crystal distortions, cations off-centering and bending of
+the oxygen octahedra, which added to the charge redistribution mediated by
+$v_\mathrm{O}$, the cations electronegativity and valence states trigger an
+effective electric polarization. Oxygen migrations for $\delta=0.125$ provides
+us with $\vert\Delta \mathbf{P}\vert$ $>\sim10 \mu$C/cm$^2$ due to a
+quantum-of-polarization differences between $\delta=0.125$ structures.
+Increasing the deficiency to $\delta=0.25$ yields $\vert\Delta \mathbf{P}\vert$
+whose O-migration resolved polarization for $\delta=0.25$ is $>\sim3
+\mu$C/cm$^2$ in the worst case scenario. Magnetism is dominated by the Fe,Co
+spin states for $\delta=0.125$ while there is a raid of Ti magnetic moments
+($\sim1\mu_{B}$) for $\delta=0.25$. Magnetic and electric order parameters
+change for variations of $\delta$ or oxygen migrations for a given deficiency.
+Our results capture characteristics observed in the end-members of the series
+SrTi(Co,Fe)O$_{3}$, and suggest the existence of a broader set of rules for
+oxygen deficient multiferroic oxides.",1910.00176v2
+2020-04-23,Effective point-charge analysis of crystal electric fields -- application to rare-earth pyrochlores and tripod kagome magnets R3Mg2Sb3O14,"An indispensable step to understand collective magnetic phenomena in
+rare-earth compounds is the determination of spatially-anisotropic single-ion
+properties resulting from spin-orbit coupling and crystal field (CF). The CF
+Hamiltonian has a discrete energy spectrum -- accessible to spectroscopic
+probes such as neutron scattering -- controlled by a number of independent
+parameters reflecting the point-symmetry of the magnetic sites. Determining
+these parameters in low-symmetry systems is often challenging. Here, we
+describe a general method to analyze CF excitation spectra using adjustable
+effective point-charges. We benchmark our method to existing neutron-scattering
+measurements on pyrochlore rare-earth oxides and obtain a universal
+point-charge model that describes a large family of related materials. We adapt
+this model to the newly discovered tripod Kagome magnets
+($R_{3}$Mg$_2$Sb$_{3}$O$_{14}$, $R$ = Tb, Ho, Er, Yb) for which we report
+broadband inelastic neutron-scattering spectra. Analysis of these data using
+adjustable point-charges yields the CF wave-functions for each compound. From
+this, we calculate thermomagnetic properties that accurately reflect our
+measurements on powder samples, and predict the effective gyromagnetic tensor
+for pseudo-spin degrees of freedom -- a crucial step to understand the exotic
+collective properties of these kagome magnets at low temperature. We present
+further applications of our method to other tripod kagome materials and
+triangular rare-earth compounds $R$MgGaO$_4$ ($R$ =Yb, Tm). Overall, this study
+establishes a widely applicable methodology to predict CF and single-ion
+properties of rare-earth compounds based on interpretable and adjustable models
+of effective point-charges.",2004.10957v3
+2017-11-15,A High-Resolution Combined Scanning Laser- and Widefield Polarizing Microscope for Imaging at Temperatures from 4 K to 300 K,"Polarized light microscopy, as a contrast-enhancing technique for optically
+anisotropic materials, is a method well suited for the investigation of a wide
+variety of effects in solid-state physics, as for example birefringence in
+crystals or the magneto-optical Kerr effect (MOKE). We present a microscopy
+setup that combines a widefield microscope and a confocal scanning laser
+microscope with polarization-sensitive detectors. By using a high numerical
+aperture objective, a spatial resolution of about 240 nm at a wavelength of 405
+nm is achieved. The sample is mounted on a $^4$He continuous flow cryostat
+providing a temperature range between 4 K and 300 K, and electromagnets are
+used to apply magnetic fields of up to 800 mT with variable in-plane
+orientation and 20 mT with out-of-plane orientation. Typical applications of
+the polarizing microscope are the imaging of the in-plane and out-of-plane
+magnetization via the longitudinal and polar MOKE, imaging of magnetic flux
+structures in superconductors covered with a magneto-optical indicator film via
+Faraday effect or imaging of structural features, such as twin-walls in
+tetragonal SrTiO$_3$. The scanning laser microscope furthermore offers the
+possibility to gain local information on electric transport properties of a
+sample by detecting the beam-induced voltage change across a current-biased
+sample. This combination of magnetic, structural and electric imaging
+capabilities makes the microscope a viable tool for research in the fields of
+oxide electronics, spintronics, magnetism and superconductivity.",1711.06204v1
+2021-03-08,Magnetic and electronic ordering phenomena in the [Ru$_2$O$_6$] honeycomb lattice compound AgRuO$_3$,"The silver ruthenium oxide AgRuO$_3$ consists of honeycomb
+[Ru$_2^{5+}$O$_6^{2-}$] layers, and can be considered an analogue of
+SrRu$_2$O$_6$ with a different intercalation stage. We present measurements of
+magnetic susceptibility and specific heat on AgRuO$_3$ single crystals which
+reveal a sharp antiferromagnetic transition at 342(3)K. The electrical
+transport in single crystals of AgRuO$_3$ is determined by a combination of
+activated conduction over an intrinsic semiconducting gap of $\approx$ 100 meV
+and carriers trapped and thermally released from defects. From powder neutron
+diffraction data a N\'eel-type antiferromagnetic structure with the Ru moments
+along the $c$ axis is derived. Raman and muon spin rotation spectroscopy
+measurements on AgRuO$_3$ powder samples indicate a further weak phase
+transition or a crossover in the temperature range 125-200 K. The transition
+does not show up in magnetic susceptibility and its origin is argued to be
+related to defects but cannot be fully clarified. The experimental findings are
+complemented by DFT-based electronic structure calculations. It is found that
+the magnetism in AgRuO$_3$ is similar to that of SrRu$_2$O$_6$, however with
+stronger intralayer and weaker interlayer magnetic exchange interactions.",2103.04815v1
+2021-03-09,Ferromagnetic metallic Sr-rich Ln$_{1/2}$A$_{1/2}$CoO$_3$ cobaltites with spontaneous spin rotation,"The Pr$_{0.50}$Sr$_{0.5}$0CoO$_3$ perovskite exhibits unique
+magnetostructural properties among the rest of ferromagnetic/metallic
+Ln$_{0.50}$Sr$_{0.50}$CoO$_3$ compounds. The sudden orthorhombic-tetragonal
+(Imma $\to$ I4/mcm) structural transition produces an unusual magnetic behavior
+versus temperature and external magnetic fields. In particular, the symmetry
+change is responsible for a spontaneous spin rotation in this metallic oxide.
+We have studied half-doped Ln$_{0.50}$(Sr$_{1-x}$A$_x$)$_{0.50}$CoO$_3$
+cobaltites varying the ionic radius rA of A-site cations (divalent cations and
+lanthanides) in order to complete the T-rA phase diagram. The influence of the
+structural distortion and the A-cations size for the occurrence of a
+spontaneous spin reorientation in the metallic state has been investigated. As
+the reorientation of the magnetization is driven by the temperature induced
+collapse of the orthorhombic distortion, a careful investigation of the
+structural symmetry is presented varying the structural distortion of the
+Sr-rich half-doped cobaltites by means of both compositional and temperature
+changes. The region in the phase diagram of these perovskites where the phase
+of magnetic symmetry Fm'm'm replaces that of Im'm'a symmetry was determined in
+this family of ferromagnetic/metallic cobaltites. In that region the
+magnetization direction has rotated 45 degrees within the a-b plane with
+respect to the second.",2103.05410v1
+2021-07-09,Failure to achieve the $J_{eff}$~=~0 state even in nearly isolated Ir$^{5+}$ in Sr$_3$NaIrO$_6$: are iridates enough for realizing true $j$-$j$ coupling?,"Spin-orbit coupling (SOC) often gives rise to interesting electronic and
+magnetic phases in an otherwise ordinary pool of paramagnetic heavy metal
+oxides. In presence of strong SOC, assumed to be working in $j$-$j$ coupling
+regime, 5$d^4$ iridates are generally speculated to possess a nonmagnetic
+$J_{eff}$~=~0 singlet ground state, which invariably gets masked due to
+different solid-state effects (e.g. hopping). Here, we try to probe the
+trueness of the atomic SOC-based proposal in an apparently 1-dimensional
+system, Sr$_3$NaIrO$_6$, possessing a 2$H$ hexagonal structure with well
+separated Ir$^{5+}$ (5$d^4$) ions. But all the detailed experimental as well as
+theoretical characterizations reveal that the ground state of Sr$_3$NaIrO$_6$
+is not nonmagnetic, rather accommodating a significantly high effective
+magnetic moment on Ir$^{5+}$ ion. However our combined dc susceptibility
+($\chi$), ${}^{23}$Na nuclear magnetic resonance (NMR),
+muon-spin-relaxation/rotation ($\mu$SR) and heat capacity ($C_p$) measurements
+clearly refute any sign of spin-freezing or ordered magnetism among the
+Ir$^{5+}$ moments due to geometrical exchange frustration, while in-depth
+zero-field (ZF) and longitudinal field (LF) $\mu$SR investigations strongly
+point towards inhomogeneous quantum spin-orbital liquid (QSOL)-like ground
+state. In addition, the linear temperature dependence of both the NMR
+spin-lattice relaxation rate and the magnetic heat capacity at low temperatures
+suggest low-lying gapless spin excitations in the QSOL phase of this material.
+Finally, we conclude that the effective SOC realised in $d^4$ iridates are
+unlikely to offer a ground state which will be consistent with a purely atomic
+$j$-$j$ coupling description.",2107.04431v1
+2022-02-16,Enhanced magnetism and suppressed magnetoelastic coupling induced by electron doping in Ca$_{1-x}$Y$_{x}$MnReO$_6$,"The Ca$_2$MnReO$_6$ double perovskite is a spin-orbit-assisted Mott insulator
+with exotic magnetic properties, including a largely non-collinear Mn$^{2+}$
+spin arrangement and nearly orthogonal coupling between such spins and the much
+smaller Re $5d$ magnetic moments. Here, the electron-doped compound
+Ca$_{1.7}$Y$_{0.3}$MnReO$_6$ is investigated. Neutron and X-ray powder
+diffraction confirm that nearly full chemical order is maintained at the Mn and
+Re sites under the Y substitution at the Ca site. X-ray absorption measurements
+and an analysis of the Mn-O/Re-O bond distances show that the Mn oxidation
+state remains stable at +2 whereas Re is reduced upon doping. The electron
+doping increases the magnetic ordering temperature from $T_c = 121$ to $150$ K
+and also enhances significantly the ferromagnetic component of the Mn spins at
+the expense of the antiferromagnetic component at the base temperature ($T=3$
+K). The lattice parameter anomalies at $T_c$ observed in the parent compound
+are suppressed by the electron doping. The possible reasons for the enhanced
+magnetism and the suppressed magnetoelastic coupling in
+Ca$_{1.7}$Y$_{0.3}$MnReO$_6$ are discussed.",2202.08220v1
+2022-04-26,"Electronic and structural properties of RbCeX$_2$ (X$_2$: O$_2$, S$_2$, SeS, Se$_2$, TeSe, Te$_2$)","Triangular lattice delafossite compounds built from magnetic lanthanide ions
+are a topic of recent interest due to their frustrated magnetism and
+realization of quantum disordered magnetic ground states. Here we report the
+evolution of the structure and electronic ground states of RbCe$X_2$ compounds,
+built from a triangular lattice of Ce$^{3+}$ ions, upon varying their anion
+character ($X_2$= O$_2$, S$_2$, SeS, Se$_2$, TeSe, Te$_2$). This includes the
+discovery of a new member of this series, RbCeO$_2$, that potentially realizes
+a quantum disordered ground state analogous to NaYbO$_2$. Magnetization and
+susceptibility measurements reveal that all compounds manifest mean-field
+antiferromagnetic interactions and, with the exception of the oxide, possess
+signatures of magnetic correlations onset below 1 K. The crystalline electric
+field level scheme is explored via neutron scattering and \textit{ab initio}
+calculations in order to model the intramultiplet splitting of the $J=5/2$
+multiplet. In addition to the two excited doublets expected within the $J=5/2$
+manifold, we observe one extra, local mode present across the sample series.
+This added mode shifts downward in energy with increasing anion mass and
+decreasing crystal field strength, suggesting a long-lived anomalous mode
+endemic to anion motion about the Ce$^{3+}$ sites.",2204.12086v2
+2022-11-12,Quantum paramagnetism in a non-Kramers rare-earth oxide: Monoclinic $\rm Pr_2Ti_2O_7$,"Little is so far known about the magnetism of the $\rm A_2B_2O_7$ monoclinic
+layered perovskites that replace the spin-ice supporting pyrochlore structure
+for $r_A/r_B>1.78$. We show that high quality monoclinic Pr$_2$Ti$_2$O$_7$
+single crystals with a three-dimensional network of non-Kramers Pr$^{3+}$ ions
+that interact through edge-sharing super-exchange interactions, form a singlet
+ground state quantum paramagnet that does not undergo any magnetic phase
+transitions down to at least 1.8 K. The chemical phase stability, structure,
+and magnetic properties of the layered perovskite Pr$_2$Ti$_2$O$_7$ were
+investigated using x-ray diffraction, transmission electron microscopy, and
+magnetization measurements. Synthesis of polycrystalline samples with the
+nominal compositions of Pr$_2$Ti$_{2+x}$O$_7$ ($-0.16 \leq x \leq 0.16$) showed
+that deviations from the Pr$_2$Ti$_2$O$_7$ stoichiometry lead to secondary
+phases of related, structures including the perovskite phase Pr$_{2/3}$TiO$_3$
+and the orthorhombic phases Pr$_4$Ti$_9$O$_{24}$ and Pr$_2$TiO$_5$. No
+indications of site disordering (stuffing and anti-stuffing) or vacancy defects
+were observed in the Pr$_2$Ti$_2$O$_7$ majority phase. A procedure for growth
+of high-structural-quality, stoichiometric single crystals of Pr$_2$Ti$_2$O$_7$
+by the traveling solvent floating zone (TSFZ) method is reported.
+Thermo-magnetic measurements of single-crystalline Pr$_2$Ti$_2$O$_7$ reveal an
+isolated singlet ground state that we associate with the low symmetry crystal
+electric field environments that split the $2J+1=9$-fold degenerate
+spin-orbital multiplets of the four differently coordinated Pr$^{3+}$ ions into
+36 isolated singlets resulting in an anisotropic temperature independent
+van-Vleck susceptibility at low $T$. A small isotropic Curie term is associated
+with 0.96(2)\% non-interacting Pr$^{4+}$ impurities.",2211.06758v2
+2022-11-28,"Insulating band gaps both below and above the Néel temperature in d-electron LaTiO3, LaVO3, SrMnO3, and LaMnO3 perovskites as a symmetry-breaking event","Compounds having an odd number of electrons with the same orbital character
+in occupied and unoccupied band edge states would be expected to have band
+degeneracy at the Fermi energy, making such reference system metals. Yet, many
+ABO3 oxide perovskites with a magnetic 3d B-atom are, in fact, insulators both
+below and above the Neel temperature. These inconsistencies between
+experimental observation and expectation have been traditionally resolved by
+invoking degeneracy-breaking physics based largely on high-order electron
+effects, such as strong interelectronic correlation (the Mott mechanism). Such
+explanations generally utilize the highest symmetry structure, considering
+microscopic degrees of freedom (m-DOF) as largely passive spectators. Yet, it
+has long been known that ABO3 perovskites can manifest an arrangement of m-DOFs
+in the form of octahedral tilting, bond dimerization, Jahn-Teller distortions,
+and ordering of local magnetic moments as part of the stabilizing intrinsic
+symmetry. Such m-DOFs are seen both by local experimental probes and
+theoretically in total energy minimization of its Born-Oppenheimer state. While
+such local structural and magnetic symmetry breaking motifs were often
+considered to be the reason for gapping of the reference system below the
+transition into Para phases, it was also often thought that above the
+transition those local motifs might vanish, requiring a different mechanism for
+gapping - such as strong correlation. Here we examine if such intrinsic
+structural and magnetic symmetry breaking might systematically explain the
+formation of insulating band gaps both below and above the magnetic transition
+and account at the same time for specific and non-accidental exceptions of the
+absence of gaping in some compounds, such as SrVO3.",2211.15563v2
+2023-10-06,"Correlations between laboratory line lists for FeH, CrH, and NiH and M-star spectra collected with ESPaDOnS and SPIRou","Molecular bands of metal oxides and hydrides dominate the optical and
+near-infrared spectra of M dwarfs. High-resolution spectra of these bands have
+immense potential for determining many properties of these stars, such as
+effective temperature, surface gravity, elemental abundances, radial velocity,
+or surface magnetic fields. Techniques are being developed to do this but
+remain limited by the current availability and accuracy of molecular data and
+spectral line lists. This paper reports metal monohydride line lists selected
+from near-infrared and visible laboratory data to show that specific bands in
+several electronic transitions can be used to identify CrH, NiH, and FeH in M
+stars and to determine radial velocities from Doppler shifts. The possibility
+of measuring magnetic fields is also investigated for FeH and CrH. We used
+systematic cross-correlation analysis between unpolarised spectra from a
+selection of M stars and state-specific laboratory line lists. These lists were
+generated from a combination of existing data and new laboratory
+laser-excitation spectra recorded at Doppler-limited resolution, in zero-field
+conditions or in magnetic fields up to 0.6 tesla. Results. We show that
+transitions at visible wavelengths in FeH and NiH, usually neglected in the
+analysis of the spectra of M-type stars, do in fact contribute to the spectra,
+and we demonstrate the influence of magnetic sensitivity on selected
+transitions in CrH and FeH. Although the new line lists focus on transitions
+recorded at temperatures significantly lower than those of stellar objects,
+they remain pertinent because they cover some band-head regions of high
+spectral density. FeH bands can provide a useful supplement to atomic lines for
+the analysis of high-resolution optical and near-infrared spectra of M dwarfs.
+We demonstrate the influence of a magnetic field on CrH signatures around 862
+nm.",2310.04497v1
+2024-02-28,Unveiling unconventional magnetism at the surface of Sr$_2$RuO$_4$,"Materials with strongly correlated electrons exhibit physical properties that
+are often difficult to predict as they result from the interactions of large
+numbers of electrons combined with several quantum degrees of freedom. The
+layered oxide perovskite Sr$_2$RuO$_4$ is a strongly correlated electron
+material that has been intensively investigated since its discovery due to its
+unusual physical properties. Whilst recent experiments have reopened the debate
+on the exact symmetry of the superconducting state in Sr$_2$RuO$_4$, a deeper
+understanding of the Sr$_2$RuO$_4$ normal state appears crucial as this is the
+background in which electron pairing occurs. Here, by using low-energy muon
+spin spectroscopy we discover the existence of magnetism at the surface of
+Sr$_2$RuO$_4$ in its normal state. We detect static weak dipolar fields yet
+manifesting below a relatively high onset temperature larger than 50 K, which
+reveals the unconventional nature of the observed magnetism. We relate the
+origin of this phase breaking time reversal symmetry to electronic ordering in
+the form of orbital loop currents that originate at the reconstructed
+Sr$_2$RuO$_4$ surface. Our observations set a reference for the discovery of
+the same magnetic phase in other materials and unveil an electronic ordering
+mechanism that can influence unconventional electron pairing with broken time
+reversal symmetry in those materials where the observed magnetic phase coexists
+with superconductivity.",2402.18359v1
+2024-03-01,Emergence of interfacial magnetism in strongly-correlated nickelate-titanate superlattices,"Strongly-correlated transition-metal oxides are widely known for their
+various exotic phenomena. This is exemplified by rare-earth nickelates such as
+LaNiO$_{3}$, which possess intimate interconnections between their electronic,
+spin, and lattice degrees of freedom. Their properties can be further enhanced
+by pairing them in hybrid heterostructures, which can lead to hidden phases and
+emergent phenomena. An important example is the LaNiO$_{3}$/LaTiO$_{3}$
+superlattice, where an interlayer electron transfer has been observed from
+LaTiO$_{3}$ into LaNiO$_{3}$ and is predicted to result in a high-spin state.
+However, macroscopic emergence of magnetic order has so far not been observed.
+Here, by using muon spin rotation, x-ray absorption, and resonant inelastic
+x-ray scattering, we present direct evidence of an emergent antiferromagnetic
+order with high magnon energy and exchange interactions at the
+LaNiO$_{3}$/LaTiO$_{3}$ interface. As the magnetism is purely interfacial, a
+single LaNiO$_{3}$/LaTiO$_{3}$ interface can essentially behave as an
+atomically thin quasi-two-dimensional antiferromagnet, potentially allowing its
+technological utilisation in advanced spintronic devices. Furthermore, its
+strong quasi-two-dimensional magnetic correlations and orbitally-polarized
+planar ligand holes make its electronic and magnetic configurations resemble
+the precursor states of superconducting cuprates and nickelates, but with an S
+$\rightarrow$ 1 spin state instead.",2403.00728v1
+2009-01-24,"Uniform mixing of antiferromagnetism and high-T_c superconductivity in multilayered copper oxides Ba_2Ca_{n-1}Cu_nO_{2n}F_2 with apical fluorines (n=2,3,4): Cu-NMR/NQR and F-NMR","We report Cu-NMR/NQR and F-NMR studies on the multilayered high-T_c copper
+oxides Ba_2Ca_{n-1}Cu_nO_{2n}F_2 with n=2,3,4, where n is the number of CuO_2
+planes. It is revealed that bi-layered Ba_2CaCu_2O_4F_2 is an underdoped
+superconductor with hole carriers, which are introduced into CuO_2 planes by an
+unexpected deviation from the nominal content of apical fluorines. In a
+previous paper, we proposed a self-doping mechanism as the origin of carrier
+doping in n=3 and n=4; in the mechanism, electrons are transferred from the
+inner CuO_2 plane (IP) to the outer one (OP). However, since it has been found
+that the bi-layered compound is hole doped, we have reexamined the
+superconducting and magnetic properties in n=3 and n=4 by Cu-NMR/NQR and F-NMR.
+The extensive NMR studies have confirmed that the apical-fluorine compounds are
+not self-doped but hole-doped, and that antiferromagnetism (AFM) and
+superconductivity (SC) coexist in a single CuO_2 plane. In n=4, the AFM
+ordering occurs at T_N = 80 K, well above T_c=55 K, where the respective AFM
+moments are M_AFM=0.11 mu_B and 0.18 mu_B at the OP and the IP. In n=3, on the
+other hand, the underdoped single IP exhibits a spontaneous moment M_AFM=0.12
+mu_B at low temperatures and a peak in the nuclear-spin-lattice relaxation rate
+1/T_1 of F at T_N=23 K, much lower than T_c = 76 K. We note that the increase
+in the number of IPs from one to two leads to an increase in T_N due to
+strengthening the interlayer coupling, although the doping levels for both
+compounds are almost comparable. The present results strongly suggest that the
+uniform mixing of AFM and SC is a general property inherent to a single CuO_2
+plane in the underdoped regime for hole-doping.",0901.3811v1
+2010-11-17,Tailoring a two-dimensional electron gas at the LaAlO3/SrTiO3 (001) interface by epitaxial strain,"Recently a metallic state was discovered at the interface between insulating
+oxides, most notably LaAlO3 and SrTiO3. Properties of this two-dimensional
+electron gas (2DEG) have attracted significant interest due to its potential
+applications in nanoelectronics. Control over this carrier density and mobility
+of the 2DEG is essential for applications of these novel systems, and may be
+achieved by epitaxial strain. However, despite the rich nature of strain
+effects on oxide materials properties, such as ferroelectricity, magnetism, and
+superconductivity, the relationship between the strain and electrical
+properties of the 2DEG at the LaAlO3/SrTiO3 heterointerface remains largely
+unexplored. Here, we use different lattice constant single crystal substrates
+to produce LaAlO3/SrTiO3 interfaces with controlled levels of biaxial epitaxial
+strain. We have found that tensile strained SrTiO3 destroys the conducting
+2DEG, while compressively strained SrTiO3 retains the 2DEG, but with a carrier
+concentration reduced in comparison to the unstrained LaAlO3/SrTiO3 interface.
+We have also found that the critical LaAlO3 overlayer thickness for 2DEG
+formation increases with SrTiO3 compressive strain. Our first-principles
+calculations suggest that a strain-induced electric polarization in the SrTiO3
+layer is responsible for this behavior. It is directed away from the interface
+and hence creates a negative polarization charge opposing that of the polar
+LaAlO3 layer. This both increases the critical thickness of the LaAlO3 layer,
+and reduces carrier concentration above the critical thickness, in agreement
+with our experimental results. Our findings suggest that epitaxial strain can
+be used to tailor 2DEGs properties of the LaAlO3/SrTiO3 heterointerface.",1011.4082v1
+2012-06-19,K-edge X-ray absorption spectra in transition metal oxides beyond the single particle approximation: shake-up many body effects,"The near edge structure (XANES) in K-edge X-ray absorption spectroscopy (XAS)
+is a widely used tool for studying electronic and local structure in materials.
+The precise interpretation of these spectra with the help of calculations is
+hence of prime importance, especially for the study of correlated materials
+which have a complicated electronic structure per se. The single particle
+approach, for example, has generally limited itself to the dominant dipolar
+cross-section. It has long been known however that effects beyond this approach
+should be taken into account, both due to the inadequacy of such calculations
+when compared to experiment and the presence of shake-up many-body satellites
+in core-level photoemission spectra of correlated materials. This effect should
+manifest itself in XANES spectra and the question is firstly how to account for
+it theoretically and secondly how to verify it experimentally. By using
+state-of-the-art first principles electronic structure calculations and 1s
+photoemission measurements we demonstrate that shake-up many-body effects are
+present in K-edge XAS dipolar spectra of NiO, CoO and CuO at all energy scales.
+We show that shake-up effects can be included in K-edge XAS spectra in a simple
+way by convoluting the single-particle first-principles calculations including
+core-hole effects with the 1s photoemission spectra. We thus describe all
+features appearing in the XAS dipolar cross-section of NiO and CoO and obtain a
+dramatic improvement with respect to the single-particle calculation in CuO.
+These materials being prototype correlated magnetic oxides, our work points to
+the presence of shake-up effects in K-edge XANES of most correlated transition
+metal compounds and shows how to account for them, paving the way to a precise
+understanding of their electronic structure.",1206.4235v1
+2012-12-12,Impurity-induced frustration: low-energy model of diluted oxides,"We provide a detailed derivation of the low-energy model for Zn-diluted
+La2CuO4 in the limit of low doping together with a study of the ground-state
+properties of that model. We consider Zn-doped La2CuO4 within a framework of
+the three-band Hubbard model, which closely describes high-Tc cuprates on the
+energy scale of the most relevant atomic orbitals. Qualitatively, we find that
+the hybridization of zinc and oxygen orbitals can result in an impurity state
+with the energy \varepsilon, which is lower than the effective Hubbard gap U.
+The low-energy, spin-only Hamiltonian includes terms of the order t^2/U and
+t^4/\varepsilon^3. That is, besides the usual nearest-neighbor superexchange
+J-terms of order t^2/U, the low-energy model contains impurity-mediated,
+further-neighbor frustrating interactions among the Cu spins surrounding
+Zn-sites in an otherwise unfrustrated antiferromagnetic background. These terms
+can be substantial when \varepsilon ~ U/2, the latter value corresponding to
+the realistic CuO2 parameters. In order to verify this spin-only model, we
+subsequently apply the T-matrix approach to study the effect of impurities on
+the antiferromagnetic order parameter. Previous theoretical studies, which
+include only the dilution effect of impurities, show a large discrepancy with
+experimental data in the doping dependence of the staggered magnetization at
+low doping. We demonstrate that this discrepancy is eliminated by including
+impurity-induced frustrations into the effective spin model with realistic CuO2
+parameters. Recent experimental study shows a significantly stronger
+suppression of spin stiffness in the case of Zn-doped La2CuO4 compared to the
+Mg-doped case and thus gives a strong support to our theory. We argue that the
+proposed impurity-induced frustrations should be important in other strongly
+correlated oxides and charge-transfer insulators.",1212.2976v2
+2013-07-15,Topotactic phase transformation of the brownmillerite SrCoO2.5 to the perovskite SrCoO3-δ,"Oxygen stoichiometry is one of the most important elements in determining the
+physical properties of transition metal oxides (TMOs). A small fractional
+change in the oxygen content, resulting in the variation of valence state of
+the transition metal, can drastically modify the materials functionalities. In
+particular, TMOs with mixed valences have attracted attention for many energy
+applications. Previous studies also showed that the ability to control the
+number of d-band electron populations and detailed spin configurations is
+critical for improved catalytic performance of TMOs. In this context,
+SrCoO$_{x}$ (2.5 < x < 3.0) is an ideal class of materials due to the existence
+of two structurally distinct topotatic phases, i.e. the brownmillerite
+SrCoO$_{2.5}$(BM-SCO) and the perovskite SrCoO$_{3}$. Especially, BM-SCO has
+atomically-ordered one-dimensional vacancy channels, which can accommodate
+additional oxygen. Moreover, SrCoO$_{x}$ exhibits a wide spectrum of physical
+properties depending on the oxygen stoichiometry. Since SrCoOx has only a
+single knob to control the Co valence state without cation doping, it is an
+attractive material for studying the valence state dependent physical
+properties. However, so far, the growth of high quality single crystalline
+materials has not been much studied due to difficulty in controlling the right
+oxidation state. In this work, we report on the epitaxial growth of BM-SCO
+single crystalline films on SrTiO3 by pulsed laser epitaxy. In order to examine
+the topotactic phase transformation to the perovskite SrCoO$_{3-\delta}$, some
+of samples were subsequently in-situ annealed at various oxygen pressure
+P(O$_{2}$). We found that post-annealing in high P(O$_{2}$) (> several hundreds
+of Torr) could fill some of oxygen vacancies accompanying systematic evolution
+in electronic, magnetic, and thermoelectric properties.",1307.3932v1
+2014-01-07,Superparamagnetic iron oxide polyacrylic acid coated γ-Fe2O3 nanoparticles does not affect kidney function but causes acute effect on the cardiovascular function in healthy mice,"This study describes the distribution of intravenously injected polyacrylic
+acid (PAA) coated {\gamma}-Fe2O3 NPs (10 mg kg-1) at the organ, cellular and
+subcellular levels in healthy BALB/cJ mice and in parallel addresses the
+effects of NP injection on kidney function, blood pressure and vascular
+contractility. Magnetic resonance imaging (MRI) and transmission electron
+microscopy (TEM) showed accumulation of NPs in the liver within 1h after
+intravenous infusion, accommodated by intracellular uptake in endothelial and
+Kupffer cells with subsequent intracellular uptake in renal cells, particularly
+the cytoplasm of the proximal tubule, in podocytes and mesangial cells. The
+renofunctional effects of NPs were evaluated by arterial acid-base status and
+measurements of glomerular filtration rate (GFR) after instrumentation with
+chronically indwelling catheters. Arterial pH was 7.46 and 7.41 in mice 0.5 h
+after injections of saline or NP, and did not change over the next 12h. In
+addition, the injections of NP did not affect arterial PCO2 or [HCO3-] either.
+Twenty-four and 96h after NP injections, the GFR averaged 11.0 and 13.0 ml
+min-1 g-1, respectively, values which were statistically comparable with
+controls (14.0 and 14.0 ml min-1 g-1). Mean arterial blood pressure (MAP)
+decreased 12-24h after NP injections (111 vs 123 min-1) associated with a
+decreased contractility of small mesenteric arteries revealed by myography to
+characterise endothelial function. In conclusion, our study demonstrates that
+accumulation of superparamagnetic iron oxide nanoparticles does not affect
+kidney function in healthy mice but temporarily decreases blood pressure.",1401.1847v1
+2015-01-20,Anomalous High-Energy Waterfall-Like Electronic Structure in 5d Transition Metal Oxide Sr2IrO4 with a Strong Spin-Orbit Coupling,"The layered 5d transition metal oxides like Sr2IrO4 have attracted
+significant interest recently due to a number of exotic and new phenomena
+induced by the interplay between the spin-orbit coupling, bandwidth W and
+on-site Coulomb correlation U. In contrast to a metallic behavior expected from
+the Mott-Hubbard model due to more spatially extended 5d orbitals and moderate
+U, an insulating ground state has been observed in Sr2IrO4. Such an insulating
+behavior can be understood by an effective J_eff=1/2 Mott insulator model by
+incorporating both electron correlation and strong spin-orbital coupling,
+although its validity remains under debate at present. In particular, Sr2IrO4
+exhibits a number of similarities to the high temperature cuprate
+superconductors in the crystal structure, electronic structure, magnetic
+structure, and even possible high temperature superconductivity. Here we report
+a new observation of the anomalous high energy electronic structure in Sr2IrO4.
+By taking high-resolution angle-resolved photoemission measurements on Sr2IrO4
+over a wide energy range, we have revealed that the high energy electronic
+structures show unusual nearly-vertical bands that extend over a large energy
+range. Such anomalous high energy behaviors resemble the high energy waterfall
+features observed in the cuprate superconductors, adding one more important
+similarity between these two systems. While strong electron correlation plays
+an important role in producing high energy waterfall features in the cuprate
+superconductors, the revelation of the high energy anomalies in Sr2IrO4 points
+to a novel route in generating exotic electronic excitations from the strong
+spin-orbit coupling and a moderate electron correlation.",1501.04687v1
+2016-01-19,Strong evidence for d-electron spin transport at room temperature at a LaAlO3/SrTiO3 interface,"A d-orbital electron has an anisotropic electron orbital and is a source of
+magnetism. The realization of a 2-dimensional electron gas (2DEG) embedded at a
+LaAlO3/SrTiO3 interface surprised researchers in materials and physical
+sciences because the 2DEG consists of 3d-electrons of Ti with extraordinarily
+large carrier mobility, even in the insulating oxide heterostructure. To date,
+a wide variety of physical phenomena, such as ferromagnetism and the quantum
+Hall effect, have been discovered in this 2DEG systems, demonstrating the
+ability of the d-electron 2DEG systems to provide a material platform for the
+study of interesting physics. However, because of both ferromagnetism and the
+Rashba field, long-range spin transport and the exploitation of spintronics
+functions have been believed difficult to implement in the d-electron 2DEG
+systems. Here, we report the experimental demonstration of room-temperature
+spin transport in the d-electron-based 2DEG at a LaAlO3/SrTiO3 interface, where
+the spin relaxation length is ca. exceeding 200 nm. Our finding, which counters
+the conventional understandings to d-electron 2DEGs, opens a new field of
+d-electron spintronics. Furthermore, this work highlights a novel spin function
+in the conductive oxide system.",1601.07568v2
+2018-11-21,Beneficial influence of Hf and Zr additions to Nb4at.%Ta on the vortex pinning of Nb$_{3}$Sn with and without an O source,"Here we show that addition of Hf to Nb4Ta can significantly improve the high
+field performance of Nb$_{3}$Sn, making it suitable for dipole magnets for
+Future Circular Collider (FCC). A big challenge for the FCC is that a realistic
+production target for FCC Nb3Sn requires ~30% improvement over current
+conductor performance. Recent success with internal oxidation(IO) of Nb-Zr
+precursor has shown significant improvement in the layer J$_{c}$ of Nb$_{3}$Sn
+wires, albeit the complication of providing an internal O$_{2}$ diffusion path
+and avoiding degradation of irreversibility field($_{irr}$). We compare Zr and
+Hf additions to the standard Nb4Ta alloy of maximum H$_{c2}$ and H$_{irr}$.
+Nb4Ta rods with 1Zr or 1Hf were made into monofilament wires with and without
+SnO$_{2}$ and their properties measured over the entire superconducting range
+up to 31 T. We found that group IV alloying of Nb4Ta raises H$_{irr}$, though
+adding O$_{2}$ still degrades this slightly. As noted in Nb1Zr studies, the
+pinning force density F$_{p}$ is strongly enhanced and its peak value shifted
+to higher field by IO. A surprising result of this work is that we found better
+properties in Nb4Ta1Hf without SnO$_{2}$, F$_{pmax}$ achieving 2.35 times that
+of the standard Nb4Ta alloy, while the oxidized Nb4Ta1Zr alloy achieved 1.54
+times that of the Nb4Ta alloy. The highest layer J$_{c}$ (16 T, 4.2 K) of 3700
+A/mm$^{2}$ was found in the SnO$_{2}$-free wire made with Nb4Ta1Hf alloy. Using
+a standard A15 cross-section fraction of 60% for modern PIT and RRP wires, we
+estimated that a non-Cu J$_{c}$ of 2200 A/mm$^{2}$ is obtainable in modern
+conductors, well above the 1500A/mm$^{2}$ FCC specification. Moreover, the best
+properties were obtained without SnO$_{2}$, the Nb4Ta1Hf alloy appears to open
+a straightforward route to enhanced properties in Nb$_{3}$Sn wires.",1811.08867v1
+2018-05-16,Insight into bulk niobium superconducting RF cavities performances by tunneling spectroscopy,"Point contact tunneling (PCT) spectroscopy measurements are reported over
+wide areas of cm-sized cut outs from niobium superconducting RF cavities. A
+comparison is made between a high-quality, conventionally processed (CP) cavity
+with a high field Q drop for acceleration field E $>$ 20 MV/m and a nitrogen
+doped (N-doped) cavity that exhibits an increasing Q up to fields approaching
+15 MV/m. The CP cavity displays hot spot regions at high RF fields where Q-drop
+occurs as well as unaffected regions (cold spots). PCT data on cold spots
+reveals a near ideal BCS density of states (DOS) with gap parameters, $\Delta$
+as high as 1.62 meV, that are among the highest values ever reported for Nb.
+Hot spot regions exhibit a wide distribution of gap values down to $\Delta
+\sim$ 1.0 meV and DOS broadening characterized by a relatively large value of
+pair-breaking rate, $\Gamma$, indicating surface regions of significantly
+reduced superconductivity. In addition, hot spots commonly exhibit Kondo
+tunneling peaks indicative of surface magnetic moments attributed to a
+defective oxide. N-doped cavities reveal a more homoegeneous gap distribution
+centered at $\Delta \sim$ 1.5 meV and relatively small values of
+$\Gamma/\Delta$. The absence of regions of significantly reduced
+superconductivity indicates that the N interstitials are playing an important
+role in preventing the formation of hydride phases and other macroscopic
+defects which might otherwise severely affect the local, surface
+superconductivity that lead to hot spot formation. The N-doped cavities also
+display a significantly improved surface oxide, i.e., increased thickness and
+tunnel barrier height, compared to CP cavities. These results help explain the
+improved performance of N-doped cavities and give insights into the origin of
+the initial increasing Q with RF amplitude.",1805.06359v1
+2018-01-24,$Ab-initio$ investigation of the thermodynamics of cation distribution and the electronic and magnetic structures in the LiMn$_2$O$_4$ spinel,"The spinel-structured lithium manganese oxide (LiMn$_2$O$_4$) is a material
+currently used as cathode for secondary lithium-ion batteries, but whose
+properties are not yet fully understood. Here, we report a computational
+investigation of the inversion thermodynamics and electronic behaviour of
+LiMn$_2$O$_4$ derived from spin-polarised density functional theory
+calculations with a Hubbard Hamiltonian and long-range dispersion corrections
+(DFT+$U-$D3). Based on the analysis of the configurational free energy, we have
+elucidated a partially inverse equilibrium cation distribution for the
+LiMn$_2$O$_4$ spinel. This equilibrium degree of inversion is rationalised in
+terms of the crystal field stabilisation effects and the difference between the
+size of the cations. We compare the atomic charges with the oxidation numbers
+for each degree of inversion. We found segregation of the Mn charge once these
+ions occupy the tetrahedral and octahedral sites of the spinel. We have
+obtained the atomic projections of the electronic band structure and density of
+states, showing that the normal LiMn$_2$O$_4$ has half-metallic properties,
+while the fully inverse spinel is an insulator. This material is in the
+ferrimagnetic state for the inverse and partially inverse cation arrangement.
+The optimised lattice and oxygen parameters, as well as the equilibrium degree
+of inversion, are in agreement with the available experimental data. The
+partially inverse equilibrium degree of inversion is important in the
+interpretation of the lithium ion migration and surface properties of the
+LiMn$_2$O$_4$ spinel.",1801.08013v1
+2020-04-28,Charge transfer induced interfacial ferromagnetism in La$_{0.7}$Sr$_{0.3}$MnO$_3$/NdNiO$_3$,"Charge transfer induced interfacial ferromagnetism and its impact on the
+exchange bias effect in La$_{0.7}$Sr$_{0.3}$MnO$_3$/NdNiO$_3$ correlated oxide
+heterostructures were investigated by soft x-ray absorption and x-ray magnetic
+circular dichroism spectra in a temperature range from 10 to 300 K. Besides the
+antiferromagnetic Ni$_3^+$ cations which are naturally part of the NdNiO$_3$
+layer, Ni$_2^+$ ions are formed at the interface due to a charge transfer
+mechanism involving the Mn element of the adjacent layer. They exhibit a
+ferromagnetic behavior due to the exchange coupling to the Mn$_4^+$ ions in the
+La$_{0.7}$Sr$_{0.3}$MnO$_3$ layer. This can be seen as detrimental to the
+strength of the unidirectional anisotropy since a significant part of the
+interface does not contribute to the pinning of the ferromagnetic layer. By
+analyzing the line shape changes of the x-ray absorption at the Ni L$_{2,3}$
+edges, the metal-insulator transition of the NdNiO$_3$ layer is resolved in an
+element specific manner. This phase transition is initiated at about 120 K, way
+above the paramagnetic to antiferromagnetic transition of NdNiO$_3$ layer which
+measured to be 50 K. Exchange bias and enhanced coercive fields were observed
+after field cooling the sample through the Neel temperature of the NdNiO$_3$
+layer. Different from La$_{0.7}$Sr$_{0.3}$MnO$_3$/LaNiO$_3$, the exchange bias
+observed in La$_{0.7}$Sr$_{0.3}$MnO$_3$/NdNiO$_3$ is due to the
+antiferromagnetism of NdNiO$_3$ and the frustration at the interface. These
+results suggest that reducing the interfacial orbital hybridization may be used
+as a tunable parameter for the strength of the exchange bias effect in
+all-oxide heterostructures which exhibit a charge transfer mechanism.",2004.13593v1
+2018-12-18,Two-dimensional Ca-Cl crystals under ambient conditions observed directly by cryo-electron microscopy,"Recently, we report the direct observation, under ambient conditions, of
+Na2Cl and Na3Cl as two-dimensional (2D) Na-Cl crystals, together with regular
+NaCl, on reduced graphene oxide membranes and on the surfaces of natural
+graphite powders from salt solutions far below the saturated concentration.
+However, what are these abnormal stoichiometries for high valence ions, such as
+calcium ions and copper ions still remain unknown. Here, using cryo-electron
+microscopy, we report the direct observation of two-dimensional (2D) Ca-Cl
+crystals on reduced graphene oxide (rGO) membranes, in which the calcium ions
+are only monovalent (i.e. +1). Remarkably, metallic properties rather than
+insulating are displayed by those CaCl crystals. We note that such CaCl
+crystals are obtained by simply incubating rGO membranes in salt solutions
+below the saturated concentration, under ambient conditions. Theoretical
+studies show that the formation of those abnormal crystals is attributed to the
+strong cation-pi interactions of the Ca2+ ions with the aromatic rings in the
+graphitic surfaces. Since strong cation-pi interactions also exist between
+other metal ions (such as Mg2+, Fe2+, Co2+, Cu2+, Cd2+, Cr2+ and Pb2+) and
+graphitic surfaces, similar 2D crystals with abnormal valence state of the
+metal cations and corresponding abnormal properties are highly expected. The 2D
+crystals with monovalent calcium ions show unusual electronic properties, and
+can be applicated in catalyzer, hydrogen storage, high-performance conducting
+electrodes and sensors. These findings also produce functionalized graphene
+including compact ""graphene-metallic CaCl-insulating CaCl2"" junction that can
+serve as transistors down to the atomic scale, and other devices for magnetic,
+optical and mechanical applications.",1812.07195v1
+2019-03-01,Anisotropic Magnetoresistance in Multiband Systems: 2DEGs and Polar Metals at Oxide Interfaces,"Low density two-dimensional electron gases (2DEGs) with spin-orbit coupling
+are highly sensitive to an in-plane magnetic field, which impacts their Fermi
+surfaces and transport properties. Such 2DEGs, formed at transition metal oxide
+surfaces or interfaces, can also undergo surface phase transitions leading to
+polar metals which exhibit electronic nematicity. Motivated by experiments on
+such systems, we theoretically study magnetotransport in $t_{2g}$ orbital
+systems, using Hamiltonians which include atomic spin-orbit coupling (SOC) and
+broken inversion symmetry, for both square symmetry (001) and hexagonal
+symmetry (111) 2DEGs. Using a numerical solution to the full multiband
+matrix-Boltzmann equation, together with insights gleaned from the impurity
+scattering overlap matrix, we explore the anisotropic magnetoresistance (AMR)
+in the presence of impurities which favor small momentum scattering. We find
+that transport in the (001) 2DEG is dominated by a single pair of bands, weakly
+coupled by impurity scattering, one of which has a larger Fermi velocity while
+the other provides an efficient current-relaxation mechanism. This leads to
+strong angle-dependent current damping and a large AMR with many angular
+harmonics. In contrast, AMR in the (111) 2DEG typically features a single
+$\cos(2\vartheta)$ harmonic, with the angle-averaged magnetoresistance being
+highly tunable by a symmetry-allowed trigonal distortion. We also explore how
+the (111) 2DEG Fermi sufaces are impacted by electronic nematicity via a
+surface phase transition into a 2D polar metal for which we discuss a Landau
+theory, and show that this leads to distinct symmetry components and higher
+angular harmonics in the AMR. Our results are in qualitative agreement with
+experiments from various groups for 2DEGs at the SrTiO$_3$ surface or the
+LaAlO$_3$-SrTiO$_3$ interface.",1903.00476v2
+2021-04-29,Observation of perfect diamagnetism and interfacial effect on the electronic structures in Nd0.8Sr0.2NiO2 superconducting infinite layers,"Nickel-based complex oxides have served as a playground for decades in the
+quest for a copper-oxide analog of the high-temperature superconductivity. They
+may provide clues towards understanding the mechanism and an alternative route
+for high-temperature superconductors. The recent discovery of superconductivity
+in the infinite-layer nickelate thin films has fulfilled this pursuit. However,
+material synthesis remains challenging, direct demonstration of perfect
+diamagnetism is still missing, and understanding of the role of the interface
+and bulk to the superconducting properties is still lacking. Here, we show
+high-quality Nd0.8Sr0.2NiO2 thin films with different thicknesses and
+demonstrate the interface and strain effects on the electrical, magnetic and
+optical properties. Perfect diamagnetism is achieved, confirming the occurrence
+of superconductivity in the films. Unlike the thick films in which the
+normal-state Hall-coefficient changes signs as the temperature decreases, the
+Hall-coefficient of films thinner than 5.5 nm remains negative, suggesting a
+thickness-driven band structure modification. Moreover, X-ray absorption
+spectroscopy reveals the Ni-O hybridization nature in doped infinite-layer
+nickelates, and the hybridization is enhanced as the thickness decreases.
+Consistent with band structure calculations on the nickelate/SrTiO3
+heterostructure, the interface and strain effect induce a dominating
+electron-like band in the ultrathin film, thus causing the sign-change of the
+Hall-coefficient.",2104.14195v2
+2022-06-23,Suppressing initial capacity fade in Li-rich Li$_5$FeO$_4$ with anionic redox by partial Co substitution,"The increasing relevance of energy storage technologies demands high-capacity
+cathode materials for Li-ion batteries. Recently, Li-rich defect anti-fluorite
+Li$_5$FeO$_4$ has emerged as a high-capacity cathode material exhibiting
+simultaneous anionic and cationic redox without significant oxygen release. But
+suffers from irreversible structural change and capacity fade during cycling.
+Herein we investigate the suppressed capacity fade reported in Co substituted
+Li$_5$FeO$_4$ and establish the optimal performance through tuning the
+concentration and oxidation state of Co. We have substituted Co at the Fe site
+and carried out a detailed analysis of structural, magnetic, electronic, and
+electrochemical properties using first-principles density functional theory
+calculations. The extended stability and suppressed capacity fading are found
+only in specific compositions depending on the Co/Li concentration and the
+oxidation state of Co. The reasons behind suppressed capacity fading in Co
+substituted systems have been unveiled on the basis of bonding analyses and
+proposed as a strategy to suppress the voltage fading reported in Li-rich
+materials due to transition metal migration. From the evaluation of
+thermodynamic stability and electronic structure,
+Li$_{5.5}$Fe$_{0.5}$Co$_{0.5}$O$_4$, Li$_5$Fe$_{0.25}$Co$_{0.75}$O$_4$, and
+Li$_{4.5}$Fe$_{0.5}$Co$_{0.5}$O$_4$ are found to exhibit better electrical
+conductivity than Li$_5$FeO$_4$. All these systems have voltage in the range of
+3 to 5 V and exhibit three dimensional Li diffusion pathway with a diffusion
+barrier height of around 0.3 eV. From Li$_5$Fe$_{0.25}$Co$_{0.75}$O$_4$, one
+can delithiate three Li-ions without structural change and oxygen release,
+therefore expected to acquire a reversible capacity of around 513 mAh/g.
+Moreover, as in pristine Li$_5$FeO$_4$, the selected Co substituted systems
+also exhibit simultaneous anionic and cationic redox without significant O2
+release.",2206.11496v1
+2022-06-29,Ultra-High Carrier Mobilities in Ferroelectric Domain Wall Corbino Cones at Room Temperature,"Recently, electrically conducting heterointerfaces between dissimilar
+band-insulators (such as lanthanum aluminate and strontium titanate) have
+attracted considerable research interest. Charge transport has been thoroughly
+explored and fundamental aspects of conduction firmly established. Perhaps
+surprisingly, similar insights into conceptually much simpler conducting
+homointerfaces, such as the domain walls that separate regions of different
+orientations of electrical polarisation within the same ferroelectric
+band-insulator, are not nearly so well-developed. Addressing this disparity, we
+herein report magnetoresistance in approximately conical 180o charged domain
+walls, which occur in partially switched ferroelectric thin film single crystal
+lithium niobate. This system is ideal for such measurements: firstly, the
+conductivity difference between domains and domain walls is extremely and
+unusually large (a factor of at least 1013) and hence currents driven through
+the thin film, between planar top and bottom electrodes, are overwhelmingly
+channelled along the walls; secondly, when electrical contact is made to the
+top and bottom of the domain walls and a magnetic field is applied along their
+cone axes (perpendicular to the thin film surface), then the test geometry
+mirrors that of a Corbino disc, which is a textbook arrangement for geometric
+magnetoresistance measurement. Our data imply carriers at the domain walls with
+extremely high room temperature Hall mobilities of up to ~ 3,700cm2V-1s-1. This
+is an unparalleled value for oxide interfaces (and for bulk oxides too) and is
+most comparable to mobilities in other systems typically seen at cryogenic,
+rather than at room, temperature.",2206.14585v1
+2022-08-30,Distinct electridelike nature of infinite-layer nickelates and the resulting theoretical challenges to calculate their electronic structure,"We demonstrate in this paper that the recently discovered infinite-layer (IL)
+nickelates have much in common with a class of materials known as electrides.
+Oxide based electrides are compounds in which topotactic removal of loosely
+bound oxygens leaves behind voids with a landscape of attractive potentials for
+electrons. We show that this is also what happens in the IL nickelates, where
+one of the two electrons (per formula unit) freed during the topotactic
+synthesis is to a large degree located in the oxygen vacancy position,
+occupying partially a local $s$-symmetry interstitial orbital, rather than
+taking part alongside the other electon in converting Ni from 3+ to a full 1+
+oxidation state. We demonstrate that the interstitial orbital in question,
+referred to by us as the zeronium $s$ or Z $s$ orbital, forms strong covalent
+bonds with neighboring Ni $3d_{3z^2-r^2}$ orbitals, which in turn facilitates
+the one-dimensional-like dispersion of the Ni $3d_{3z^2-r^2}$ band along the
+$c$-axis direction, leading also to a possible large out-of-plane coupling
+between Ni magnetic moments. This finding, reinforced by our electron
+localization function analysis, points to a fundamental distinction between the
+nickelates and the structurally analogous cuprates, may explain the absence of
+superconductivity in hydrogen-poor samples, and is certainly in agreement with
+the observed large $z$-polarized component in the Ni $L_3$-edge x-ray
+absorption spectra. In addition, by using DFT+U calculations as an
+illustration, we show that the electride-like nature of the IL nickelates is
+one of the main reasons for the theoretical difficulty in determining the much
+debated elusive Fermi surface of these novel superconductors and aslo in
+exploring the possibility of them becoming excitonic insulators at low
+temperatures.",2208.14556v2
+2019-04-10,Hard x-ray standing-wave photoemission insights into the structure of an epitaxial Fe/MgO multilayer magnetic tunnel junction,"The Fe/MgO magnetic tunnel junction is a classic spintronic system, with
+current importance technologically, and interest for future innovation. The key
+magnetic properties are linked directly to the structure of hard-to-access
+buried interfaces, and the Fe and MgO components near the surface are unstable
+when exposed to air, making a deeper probing, non-destructive, in-situ
+measurement ideal for this system. We have thus applied hard x-ray
+photoemission spectroscopy (HXPS) and standing-wave (SW) HXPS in the few keV
+energy range to probe the structure of an epitaxially-grown MgO/Fe
+superlattice. The superlattice consists of 9 repeats of MgO grown on Fe by
+magnetron sputtering on an MgO (001) substrate, with a protective Al2O3 capping
+layer. We determine through SW-HXPS that 8 of the 9 repeats are similar and
+ordered, with a period of 33 $\pm$ 4 angstrom, with minor presence of FeO at
+the interfaces and a significantly distorted top bilayer with ca. 3 times the
+oxidation of the lower layers at the top MgO/Fe interface. There is evidence of
+asymmetrical oxidation on the top and bottom of the Fe layers. We find
+agreement with dark-field scanning transmission electron microscope (STEM) and
+x-ray reflectivity measurements. Through the STEM measurements we confirm an
+overall epitaxial stack with dislocations and warping at the interfaces of ca.
+5 angstrom. We also note a distinct difference in the top bilayer, especially
+MgO, with possible Fe inclusions. We thus demonstrate that SW-HXPS can be used
+to probe deep buried interfaces of novel magnetic devices with few angstrom
+precision.",1904.04999v2
+2008-08-08,Chemistry of layered d-metal pnictide oxides and their potential as candidates for new superconductors,"Layered d-metal pnictide oxides are a unique class of compounds which
+consists of characteristic d-metal pnictide layers and metal oxide layers. More
+than 100 of these layered compounds, including the recently discovered Fe-based
+superconducting pnictide oxides, can be classified into 9 structure types.
+These structure types and the chemical and physical properties of the
+characteristic d-metal pnictide layers and metal oxide layers of the layered
+d-metal pnictide oxides are reviewed and discussed. Furthermore, possible
+approaches to design new superconductors based on these layered d-metal
+pnictide oxides are proposed.",0808.1158v6
+2009-08-12,Electronic structure and ionicity of actinide oxides from first principles calculations,"The ground state electronic structures of the actinide oxides AO, A2O3 and
+AO2 (A=U, Np, Pu, Am, Cm, Bk, Cf) are determined from first-principles
+calculations, using the self-interaction corrected local spin-density (SIC-LSD)
+approximation. Emphasis is put on the degree of f-electron localization, which
+for AO2 and A2O3 is found to follow the stoichiometry, namely corresponding to
+A(4+) ions in the dioxide and A(3+) ions in the sesquioxides. In contrast, the
+A(2+) ionic configuration is not favorable in the monoxides, which therefore
+become metallic. The energetics of the oxidation and reduction of the actinide
+dioxides is discussed, and it is found that the dioxide is the most stable
+oxide for the actinides from Np onwards. Our study reveals a strong link
+between preferred oxidation number and degree of localization which is
+confirmed by comparing to the ground state configurations of the corresponding
+lanthanide oxides. The ionic nature of the actinide oxides emerges from the
+fact that only those compounds will form where the calculated ground state
+valency agrees with the nominal valency expected from a simple charge counting.",0908.1806v1
+2010-04-29,Internal Interface Strains Effects on UO2/U3O7 Oxidation Behaviour,"The growth of a U3O7 oxide layer during the anionic oxidation of UO2 pellets
+induced very important mechanical stresses due to the crystallographic lattice
+parameters differences between UO2 and its oxide. These stresses, combined with
+the chemical processes of oxidation, can lead to the cracking of the system,
+called chemical fragmentation. We study the crystallographic orientation of the
+oxide lattice growing at the surface of UO2, pointing the fact that epitaxy
+relations at interface govern the coexistence of UO2 and U3O7. In this work,
+several results are given: - Determination of the epitaxy relations between the
+substrate and its oxide thanks to the Bollmann's method; epitaxy strains are
+deduced. - Study of the coexistence of different domains in the U3O7
+(crystallographic compatibility conditions at the interface between two phases:
+Hadamard conditions). - FEM simulations of a multi-domain U3O7 connected to a
+UO2 substrate explain the existence of a critical thickness of U3O7 layer.",1004.5295v1
+2011-06-16,Silicon dry oxidation kinetics at low temperature in the nanometric range: Modeling and experiment,"Kinetics of silicon dry oxidation are investigated theoretically and
+experimentally at low temperature in the nanometer range where the limits of
+the Deal and Grove model becomes critical. Based on a fine control of the
+oxidation process conditions, experiments allow the investigation of the growth
+kinetics of nanometric oxide layer. The theoretical model is formulated using a
+reaction rate approach. In this framework, the oxide thickness is estimated
+with the evolution of the various species during the reaction. Standard
+oxidation models and the reaction rate approach are confronted with these
+experiments. The interest of the reaction rate approach to improve silicon
+oxidation modeling in the nanometer range is clearly demonstrated.",1106.3160v2
+2012-03-09,Thermodynamic Oxidation and Reduction Potentials of Photocatalytic Semiconductors in Aqueous Solution,"We introduce an approach to calculate the thermodynamic oxidation and
+reduction potentials of semiconductors in aqueous solution. By combining a
+newly-developed ab initio calculation for compound formation energy and band
+alignment with electrochemistry experimental data, this approach can be used to
+predict the stability of almost any compound semiconductor in aqueous solution.
+30 photocatalytic semiconductors have been studied, and a graph (a simplified
+Pourbaix diagram) showing their valence/conduction band levels and
+oxidation/reduction potentials is produced. Based on this graph, we have
+studied the stabilities and trends against the oxidative and reductive
+photocorrosion for compound semiconductors. We found that, only metal oxides
+can be thermodynamically stable when used as the n-type photoanodes. All the
+non-oxides are unstable due to easy oxidation by the photogenerated holes, but
+they can be resistant to the reduction by electrons, thus stable as the p-type
+photocathodes.",1203.1970v1
+2012-12-27,Molecular theory of graphene oxide,"Applying to graphene oxides, molecular theory of graphene is based on the
+oxide molecular origin when it is considered as a final product in the
+succession of a graphene molecule polyderivatives related to a particular
+oxidation reaction. The graphene oxide structure is created in due course of
+calculations following the algorithms that take into account the graphene
+molecules natural radicalization, correlation of odd electrons, an extremely
+strong influence of structure on properties, a sharp response of the molecule
+behavior on small action of external factors. Taking together, the theory
+facilities has allowed for getting a clear, transparent and understandable
+explanation of hot points of the graphene oxide chemistry and suggesting
+reliable models of both chemically produced and chemically reduced graphene
+oxides.",1212.6413v1
+2013-04-30,Carbon mono and dioxide hydrogenation over pure and metal oxide decorated graphene oxide substrates: insight from DFT,"Based on first principles density functional theory calculations we explore
+the energetics of the conversion of carbon mono and dioxide to methane over
+graphene oxide surfaces. Similar to the recently discovered hydration of
+various organic species over this catalyst, the transfer of hydrogen atoms from
+hydroxyl groups of graphene oxide provide a step by step transformation
+hydrogenation of carbon oxides. Estimated yields of modeled reactions at room
+temperature are about 0.01% for the carbon mono and dioxide. For the modeling
+of graphene oxide/metal oxide composites, calculations in the presence of MO_2
+(where M = V, Cr, Mn, Fe) have been performed. Results of these calculations
+demonstrate significant decreases of the energy costs and increases of reaction
+yields to 0.07%, which is comparable to the efficiency of these reactions over
+platinum and ruthenium-based photocatalysts. Increasing the temperature to the
+value 100C should provide the total conversion of carbon mono and dioxides.",1304.7929v1
+2013-07-23,Untangling the role of oxide in Ga-assisted growth of GaAs nanowires on Si substrates,"The influence of the oxide in Ga-assisted growth of GaAs nanowires on Si
+substrates is investigated. Three different types of oxides with different
+structure and chemistry are considered. We observe that the critical oxide
+thicknesses needed for achieving nanowire growth depends on the nature of oxide
+and how it is processed. Additionally, we find that different growth conditions
+such as temperature and Ga rate are needed for successful nanowire growth on
+different oxides. We generalize the results in terms of the characteristics of
+the oxides such as surface roughness, stoichiometry and thickness. These
+results constitute a step further towards the integration of GaAs technology on
+the Si platform.",1307.6113v1
+2014-07-31,Compact chromium oxide thin film resistors for use in nanoscale quantum circuits,"We report on the electrical characterisation of a series of thin chromium
+oxide films, grown by dc sputtering, to evaluate their suitability for use as
+on-chip resistors in nanoelectronics. By increasing the level of oxygen doping,
+the room-temperature sheet resistance of the chromium oxide films was varied
+from 28$\Omega / \square$ to 32.6k$\Omega / \square$. The variation in
+resistance with cooling to 4.2K in liquid helium was investigated; the sheet
+resistance at 4.2K varied with composition from 65$\Omega / \square$ to above
+20G$\Omega / \square$. All of the films measured displayed ohmic behaviour at
+all measured temperatures. For on-chip devices for quantum phase-slip
+measurements using niobium-silicon nanowires, interfaces between
+niobium-silicon and chromium oxide are required. By characterising the
+interface contact resistance, we found that a gold intermediate layer is
+favourable: the specfic contact resistivity of chromium-oxide-to-gold
+interfaces was 0.15 m$\Omega$cm$^2$, much lower than the value for direct
+chromium-oxide to niobium-silicon interfaces, 65m$\Omega$cm$^2$. We conclude
+that these chromium oxide films are suitable for use in nanoscale circuits as
+high-value resistors, with resistivity tunable by oxygen content.",1407.8467v1
+2015-05-18,High-Q Tantalum Oxide Nanomechanical Resonators by Laser-Oxidation of TaSe2,"Controlling the strain in two-dimensional materials is an interesting avenue
+to tailor the mechanical properties of nanoelectromechanical systems. Here we
+demonstrate a technique to fabricate ultrathin tantalum oxide nanomechanical
+resonators with large stress by laser-oxidation of nano-drumhead resonators
+made out of tantalum diselenide (TaSe2), a layered 2D material belonging to the
+metal dichalcogenides. Prior to the study of their mechanical properties with a
+laser interferometer, we checked the oxidation and crystallinity of the
+freely-suspended tantalum oxide in a high-resolution electron microscope. We
+show that the stress of tantalum oxide resonators increase by 140 MPa (with
+respect to pristine TaSe2 resonators) which causes an enhancement of quality
+factor (14 times larger) and resonance frequency (9 times larger) of these
+resonators.",1505.04727v2
+2016-04-21,Effects of Oxygen Contamination on Monolayer GeSe: A computational study,"Natural oxidation is a common degradation mechanism of both mechanical and
+electronic properties for most of the new two-dimensional materials. From
+another perspective, controlled oxidation is an option to tune material
+properties, expanding possibilities for real-world applications. Understanding
+the electronic structure modifications induced by oxidation is highly desirable
+for new materials like monolayer GeSe, which is a new candidate for
+near-infrared photodetectors. By means of first-principles calculations, we
+study the influence of oxygen defects on the structure and electronic
+properties of the single layer GeSe. Our calculations show that the oxidation
+is an exothermic process, and it is nucleated in the germanium sites. The
+oxidation can cause severe local deformations on the monolayer GeSe structure
+and introduces a deep state in the bandgap or a shallow state near the
+conduction band edge. Furthermore, the oxidation increases the bandgap by up to
+23 %, and may induce direct to indirect bandgap transitions. These results
+suggest that the natural or intentionally induced monolayer GeSe oxidation can
+be a source of new optoelectronic properties, adding another important building
+block to the two-dimensional layered materials.",1604.06322v1
+2016-06-09,"Oxygen Point Defect Chemistry in Ruddlesden-Popper Oxides (La$_{1-x}$Sr$_{x}$)$_{2}$MO$_{4{\pm}δ}$ (M = Co, Ni, Cu)","Stability of oxygen point defects in Ruddlesden-Popper oxides
+(La$_{1-x}$Sr$_{x}$)$_{2}$MO$_{4{\pm}{\delta}}$ (M = Co, Ni, Cu) is studied
+with density functional theory calculations to determine their stable sites,
+charge states, and energetics as functions of Sr content ($x$), transition
+metal (M) and defect concentration ({\delta}). We demonstrate that the dominant
+O point defects can change between oxide interstitials, peroxide interstitials,
+and vacancies. Generally, increasing $x$ and atomic number of M stabilizes
+peroxide over oxide interstitials, as well as vacancies over both peroxide and
+oxide interstitials; increasing {\delta} destabilizes both oxide interstitials
+and vacancies, but affects little peroxide interstitials. We also demonstrate
+that the O 2$p$-band center is a powerful descriptor for these materials and
+correlates linearly with the formation energy of all the defects. The trends of
+formation energy versus $x$, M and {\delta} and the correlation with O
+2$p$-band center are explained in terms of oxidation chemistry and electronic
+structure.",1606.02963v1
+2017-08-10,Numerical simulation of oxidation processes in a cross-flow around tube bundles,"An oxidation process is simulated for a bundle of metal tubes in a
+cross-flow. A fluid flow is governed by the incompressible Navier-Stokes
+equations. To describe the transport of oxygen, the corresponding
+convection-diffusion equation is applied. The key point of the model is related
+to the description of oxidation processes taking into account the growth of a
+thin oxide film in the quasi-stationary approximation. Mathematical modeling of
+oxidant transport in a tube bundle is carried out in the 2D approximation. The
+numerical algorithm employed in the work is based on the finite-element
+discretization in space and the fully implicit discretization in time. The tube
+rows of a bundle can be either in-line or staggered in the direction of the
+fluid flow velocity. The growth of the oxide film on tube walls is predicted
+for various bundle structures using the developed oxidation model.",1708.04138v1
+2018-02-21,Non-equilibrium Solute Capture in Passivating Oxide Films,"If all humans vanished tomorrow, almost every metal structure would collapse
+within a century or less, the metal converting to an oxide. In applications
+ranging from the mature technology of nuts and bolts to high technology
+batteries, nuclear fuels and turbine engines, protective oxide films are
+critical to limiting oxidation. To date models of these oxide films have
+assumed that they form thermodynamic equilibrium stable or metastable phases
+doped within thermodynamic solubility limits. Here we demonstrate
+experimentally and theoretically the formation of unusual non-equilibrium oxide
+phases, that can be predicted using a scientific framework for solute capture
+at a moving oxide/substrate interface. The theory shows that solute capture is
+likely a generic process for many electrochemical processes, and suggests that
+similar phenomena yielding non-equilibrium phases can occur and be predicted
+for a wide range of other processes involving solid-fluid and solid-solid
+chemical reactions.",1802.07685v1
+2014-03-19,Graphene Oxide flakes: methods and techniques for properties at interfaces,"Graphene Oxide and reduced Graphene Oxide are intriguing materials for
+photonics and electronic devices both for intrinsic characteristics and as
+precursors for the synthesis of graphene. Whatever the application and the
+engineering purpose, a fine control of the chemical and physical properties is
+required since the performances of graphene based systems depend on the
+reduction state of Graphene Oxide and can be strongly affected by interfaces
+interactions and neighboring effects. Then, a method for a local control of
+electric, electronic and chemical properties is required. The synergic
+application of Near Edge X ray Absorption Fine Structure Spectroscopy and
+Conductive Atomic Force Microscopy is a powerful way for such purpose allowing
+a full characterization of simple and composite samples, including specimens
+with dielectric discontinuities. Graphene Oxide/Gold (GO/Au) and Graphene
+Oxide/Silicon Oxide (GO/SiO2) have been selected as proof by example. The
+results show that the approach allow to relate chemical, electronic and
+physical properties to morphological features and local conductance behavior.",1403.4738v1
+2018-09-01,Controlled Layer-by-Layer Oxidation of MoTe2 via O3 Exposure,"Growing uniform oxides with various thickness on TMDs is one of the biggest
+challenges to integrate TMDs into complementary metal oxide semiconductor
+(CMOS) logic circuits. Here, we report a layer-by-layer oxidation of atomically
+thin MoTe2 flakes via ozone (O3) exposure. The thickness of MoOx oxide film
+could be tuning with atomic-level accuracy simply by varying O3 exposure time.
+Additionally, MoOx-covered MoTe2 shows a hole-dominated transport behavior. Our
+findings point to a simple and effective strategy for growing homogenous
+surface oxide film on MoTe2, which is promising for several purposes in
+metal-oxide-semiconductor transistor, ranging from surface passivation to
+dielectric layers.",1809.00119v1
+2019-10-25,Macroscopic visualization of fast electrochemical reaction of SrCoOx oxygen sponge,"Strontium cobaltite (SrCoOx) is known as a material showing fast topotactic
+electrochemical Redox reaction so-called oxygen sponge. Although atomic scale
+phenomenon of the oxidation of SrCoO2.5 into SrCoO3 is known, the macroscopic
+phenomenon has not been clarified yet thus far. Here, we visualize the
+electrochemical oxidation of SrCoOx macroscopically. SrCoOx epitaxial films
+with various oxidation states were prepared by the electrochemical oxidation of
+SrCoO2.5 film into SrCoO3-d film. Steep decrease of both resistivity and the
+absolute value of thermopower of electrochemically oxidized SrCoOx epitaxial
+films indicated the columnar oxidation firstly occurred along with the surface
+normal and then spread in the perpendicular to the normal. Further, we directly
+visualized the phenomena using the conductive AFM. This macroscopic image of
+the electrochemical oxidation would be useful to develop a functional device
+utilizing the electrochemical redox reaction of SrCoOx.",1910.11465v1
+2020-12-08,Scaled Atomic-Layer-Deposited Indium Oxide Nanometer Transistors with Maximum Drain Current Exceeding 2 A/mm at Drain Voltage of 0.7 V,"In this work, we demonstrate scaled back-end-of-line (BEOL) compatible indium
+oxide (In2O3) transistors by atomic layer deposition (ALD) with channel
+thickness (Tch) of 1.0-1.5 nm, channel length (Lch) down to 40 nm, and
+equivalent oxide thickness (EOT) of 2.1 nm, with record high drain current of
+2.0 A/mm at VDS of 0.7 V among all oxide semiconductors. Enhancement-mode In2O3
+transistors with ID over 1.0 A/mm at VDS of 1 V are also achieved by
+controlling the channel thickness down to 1.0 nm at atomic layer scale. Such
+high current density in a relatively low mobility amorphous oxide semiconductor
+is understood by the formation of high density 2D channel beyond 4E13 /cm2 at
+HfO2/In2O3 oxide/oxide interface.",2012.04789v1
+2017-04-30,Band offsets at amorphous-crystalline $Al_2O_3-SrTiO_3$ oxide interfaces,"2D electron gases (2DEGs) formed at oxide interfaces provide a rich testbed
+for fundamental physics and device applications. While the discussion of the
+physical origins of this phenomenon continues, the recent discovery of oxide
+2DEGs at non-epitaxial interfaces between amorphous and crystalline oxides
+provides useful insight onto this debate. Furthermore, using amorphous oxides
+offers a low-cost route towards realizing 2DEGs for device applications. In
+this work, the band offsets of a simple model system of amorphous-crystalline
+oxide interface are investigated. The model system consists of amorphous
+$Al_2O_3$ grown on single-crystalline (001) $SrTiO_3$. X-ray photoelectron
+spectroscopy is employed to study the chemical states, band gap and band
+offsets at the interface. The density of ionic defects near the interface is
+found to be below the detection limit, and the interface is found to be
+insulating. Analysis of the relative band structure yields significant
+interfacial barriers, exceeding 1.05 eV for holes and 2.0 eV for electrons. The
+barrier for holes is considerably larger than what is known for related
+materials systems, outlining the promise of using amorphous $Al_2O_3$ as an
+effective and simple insulator, an important building block for oxide-based
+field effect devices.",1705.00315v2
+2018-06-21,Anomalous dielectric response at intermixed oxide heterointerfaces,"Two-dimensional charge carrier accumulation at oxide heterointerfaces
+presents a paradigm shift for oxide electronics. Like a capacitor, interfacial
+charge buildup couples to an electric field across the dielectric medium. To
+prevent the so-called polar catastrophe, several charge screening mechanisms
+emerge, including polar distortions and interfacial intermixing which reduce
+the sharpness of the interface. Here, we examine how atomic intermixing at
+oxide interfaces affect the balance between polar distortions and electric
+potential across the dielectric medium. We find that intermixing moves the peak
+charge distribution away from the oxide/oxide interface; thereby changing the
+direction of polar distortions away from this boundary with minimal effect on
+the electric field. This opposing electric field and polar distortions is
+equivalent to the transient phase transition tipping point observed in double
+well ferroelectrics; resulting in an anomalous dielectric response -- a
+possible signature of local negative differential capacitance, with
+implications for designing dissipationless oxide electronics.",1806.08382v1
+2018-08-07,Thresholds and bistability in HIV infection models with oxidative stress,"Oxidative stress, a reaction caused by the imbalance between the reactive
+oxygen species of human organism and its ability to detoxify reactive
+intermediates and to repair the resulting damage plays an important role in
+HIV-infections. On one hand, HIV infection is responsible for the chronic
+oxidative stress of the patients. On the other hand, the oxidative stress
+contributions to the HIV disease pathogenesis. In this paper, we integrate
+oxidative stress into an HIV infection model to investigate its effects on the
+virus dynamics. Through mathematical analysis, we obtain the basic reproduction
+number R0 of the model which describes the persistence of viruses. In
+particular, we show that for R0 > 1, the model has a bistable interval with
+virus rebound threshold and elite control threshold. Numerical simulations and
+bifurcation analysis are presented to illustrate the viral dynamics under
+oxidative stress. Our investigation reveals the interplay between viruses and
+the reaction of human organism including immune response and oxidative stress,
+and their effects on the health of human being.",1808.02276v1
+2018-12-05,Influence of composition and heating schedules on compatibility of FeCrAl alloys with high-temperature steam,"FeCrAl alloys are proposed and being intensively investigated as alternative
+accident tolerant fuel (ATF) cladding for nuclear fission application. Herein,
+the influence of major alloy elements (Cr and Al), reactive element effect and
+heating schedules on the oxidation behavior of FeCrAl alloys in steam up to
+1500{\deg}C was examined. In case of transient ramp tests, catastrophic
+oxidation, i.e. rapid and complete consumption of the alloy, occurred during
+temperature ramp up to above 1200{\deg}C for specific alloys. The maximum
+compatible temperature of FeCrAl alloys in steam increases with raising Cr and
+Al content, decreasing heating rates during ramp period and doping of yttrium.
+Isothermal oxidation resulted in catastrophic oxidation at 1400{\deg}C for all
+examined alloys. However, formation of a protective alumina scale at
+1500{\deg}C was ascertained despite partial melting. The occurrence of
+catastrophic oxidation seems to be controlled by dynamic competitive mechanisms
+between mass transfer of Al from the substrate and transport of oxidizing gas
+through the scale both toward the metal/oxide scale interface.",1812.01850v1
+2019-02-12,Electro-Oxidation of p-Silicon in Fluoride-Containing Electrolyte: A Physical Model for the Regime of Negative Differential Resistance,"When Si is anodically oxidized in a fluoride containing electrolyte, an oxide
+layer is grown. Simultaneously, the layer is etched by the fluoride containing
+electrolyte. The resulting stationary state exhibits a negative slope of the
+current-voltage characteristics in a certain range of applied voltage. We
+propose a physical model that reproduces this negative slope. In particular,
+our model assumes that the oxide layer consists of both partially and fully
+oxidized Si and that the etch rate depends on the effective degree of
+oxidation. Finally, we show that our simulations are in good agreement with
+measurements of the current-voltage characteristics, the oxide layer thickness,
+the dissolution valence, and the impedance spectra of the electrochemical
+system.",1902.04328v1
+2019-02-15,Record-high photocatalytic rate at single atomic metal oxide,"Metal oxides have been extensively investigated and applied in environmental
+remediation and protection, energy conversion and storage. Most of these
+diverse applications are results of a large diversity of the electronic states
+of metal oxides. Noticeably, however, numerous metal oxides have obstacles for
+applications in catalysis because of low density of active sites in these
+materials. Size reduction of oxide catalyst is a strategy to improve the active
+site density. Here, we demonstrate the fabrication of single atomic metal oxide
+in which the oxide size reaches its minimum. However, the catalytic mechanism
+in this SATO is determined by a quasi atom physics which is fundamentally
+distinct from the traditional size effect, and also is in contrast to the
+standard condensed matter physics. SATO results in a record high and stable
+sunlight photocatalytic degradation rate of 0.24, which exceeds those of
+available photocatalysis by approximately two orders of magnitude. The
+photocatalytic process is enabled by a quasi atom physical mechanism, in which,
+an electron in the spin up channel is excited from HOMO to LUMO+1 state, which
+can only occur in SATO with W5+.",1902.05697v1
+2019-02-18,Asymmetric Oxidation of Giant Vesicles triggers Curvature-associated Shape Transition and Permeabilization. Running title: Oxidation of Vesicles produces Curvature,"(200 words) Oxidation of unsaturated lipids is a fundamental process involved
+in cell bioenergetics as well as in cell death. Using giant unilamellar
+vesicles and a chlorin photosensitizer, we asymmetrically oxidized the outer or
+inner monolayers of lipid membranes. We observed different shape transitions
+such as oblate to prolate and budding, which are typical of membrane curvature
+modifications. The asymmetry of the shape transitions is in accordance with a
+lowered effective spontaneous curvature of the leaflet being targeted. We
+interpret this effect as a decrease in the preferred area of the targeted
+leaflet compared to the other, due to the secondary products of oxidation
+(cleaved-lipids). Permeabilization of giant vesicles by light-induced oxidation
+is observed after a lag and is characterized in relation with the
+photosensitizer concentration. We interpret permeabilization as the opening of
+a pore above a critical membrane tension, resulting from the budding of
+vesicles. The evolution of photosensitized giant vesicle lysis tension was
+measured and yields an estimation of the effective spontaneous curvature at
+lysis. Additionally photo-oxidation was shown to be fusogenic.",1902.06638v1
+2019-11-20,Two-dimensional modeling of the self-limiting oxidation in silicon and tungsten nanowires,"Self-limiting oxidation of nanowires has been previously described as a
+reaction- or diffusion-controlled process. In this letter, the concept of
+finite reactive region is introduced into a diffusion-controlled model, based
+upon which a two-dimensional cylindrical kinetics model is developed for the
+oxidation of silicon nanowires and is extended for tungsten. In the model,
+diffusivity is affected by the expansive oxidation reaction induced stress. The
+dependency of the oxidation upon curvature and temperature is modeled. Good
+agreement between the model predictions and available experimental data is
+obtained. The developed model serves to quantify the oxidation in
+two-dimensional nanostructures and is expected to facilitate their fabrication
+via thermal oxidation techniques. https://doi.org/10.1016/j.taml.2016.08.002",1911.08908v1
+2020-04-14,Amorphous Mo-Ta oxide nanotubes for long-term stable Mo oxide based supercapacitors,"With a large-scale usage of portable electric appliances, a high demand for
+increasingly high density energy storage devices has emerged. MoO3 has, in
+principle, a large potential as negative electrode material in supercapacitive
+devices, due to high charge densities that can be obtained from its reversible
+redox reactions. Nevertheless, the extremely poor electrochemical stability of
+MoO3 in aqueous electrolytes prevents a practical use in high capacitance
+devices. In this work, we describe how to overcome this severe stability issue
+by forming amorphous molybdenum oxide/tantalum oxide nanotubes by anodic
+oxidation of a Mo-Ta alloy. The presence of a critical amount of Ta-oxide (> 20
+at-%) prevents the electrochemical decay of the MoO3 phase and thus yields an
+extremely high stability. Due to the protection provided by tantalum oxide, no
+capacitance losses are measureable after 10000 charg-ing/discharging cycles.",2005.00532v1
+2020-06-10,Investigation of energetics of 1:1 stoichiometric Al/PVP-fuel and nc-CeO2-oxidizer nanocomposite material,"The investigations of the nanostructured-Al (nano-Al) based thermo-oxidative
+reaction attributes are detailed in this chapter-5. Two products are selected
+for the thermo-oxidative reaction studies. They are (1) Nano-Al embedded in the
+PVP matrix (will be termed as fuel) and (2) its physically mixed 1:1
+stoichiometric nanocomposite processed with the ultrafine nc-ceria oxidizer
+(also will be termed as nanoenergetic material (NEM)), respectively. The
+graphical abstract presented below illustrates an overview of the
+thermo-oxidative reaction of fuel tracked employing thermogravimetric analysis
+(TGA) investigation. Similar TGA experimentation of the designed NEMs is
+carried out to gather scientific information validating, whether or not a
+desired enhanced attribute is achieved. Also, in coincidence with the TGA
+oxidation event, a synchronous exothermic energy release event in differential
+scanning calorimetry (DSC) trace is observed. The above mentioned two products
+and their thermo-oxidative reaction behavior employing TGA/DTA and TGA/DSC
+thermal traces are compared and interpreted based on the data available in the
+literature.",2006.05972v1
+2020-11-17,Effect of surface mechanical treatment on the oxidation behavior of FeAl-model alloy,"Fe based alloys are commonly used in almost every sector of human life. For
+different reasons, the surfaces of the real parts are prepared using different
+methods, e.g., mirror-like polishing, grit-blasting, etc. The purpose of the
+present work is to answer the question how the surface preparation influences
+the oxidation behavior of Fe-based alloys. To answer this question, a high
+purity model alloy, Fe 5 wt Al, was isothermally oxidized in a
+thermogravimetrical furnace. The post-exposure analysis included SEM/EDS (WDS)
+and XRD. The surface roughness was determined by a contact and laser
+profilometer. The obtained results demonstrate that the mechanical surface
+preparation influences oxidation kinetics as well as the microstructure of the
+oxide scale formed on the alloy at both studied temperatures. Namely, polishing
+and grinding caused local formation of Fe-rich nodules and sub-layer of
+protective Al2O3. In contrast, gritblasting leads to the formation of a thick
+outer Fe-oxide and internal aluminum nitridation. A significant increase in the
+oxidation rate of the material after gritblasting was attributed to grain
+refinement in the near-surface region, resulting in an increase in easy
+diffusion paths, namely grain boundaries.",2011.08913v1
+2021-02-01,Thermal Conductivity Mapping of Oxidized SiC SiC Composites by Time Domain Thermoreflectance with Heterodyne Detection,"Silicon carbide silicon carbide (SiC SiC) composites are often used in
+oxidizing environments at high temperatures. Measurements of the thermal
+conductance of the oxide layer provide a way to better understand the oxidation
+process with high spatial resolution. We use time domain thermoreflectance
+(TDTR) to map the thermal conductance of the oxide layer and the thermal
+conductivity of the SiC SiC composite with a spatial resolution of 3 {\mu}m.
+Heterodyne detection using a 50 kHz modulated probe beam and a 10 MHz modulated
+pump suppresses the coherent pick-up and enables faster data acquisition than
+what has previously been possible using sequential demodulation. By analyzing
+the noise of the measured signals, we find that in the limit of small
+integration time constants or low laser powers, the dominant source of noise is
+the input noise of the preamplifier. The thermal conductance of the oxide that
+forms on the fiber region is lower than the oxide on the matrix due to small
+differences in thickness and thermal conductivity.",2102.01233v1
+2021-10-22,The interaction between phosphorene oxide and the villin headpiece,"Phosphorene, a novel member of the two-dimensional nanomaterial family, has
+been demonstrated a great potential in biomedical applications, such as
+photothermal therapy, drug delivery and antibacterial. However, phosphorene is
+unstable and easily oxidized in an aerobic environment. In this paper, using
+the larger-scale molecular dynamics simulations, we investigated the disruption
+of phosphorene oxide (PO) to the structure of a model protein, villin headpiece
+subdomain (HP35). It shows that the disruption of PO nanosheets to protein
+structure enhances with the increase of the oxidation concentration of PO, but
+the oxidation mode has almost no effect on the PO-HP35 interaction. At low
+oxidation concentration, PO is good biocompatibility to HP35. Oxygen atoms
+filled into the groove region in puckered surface of phosphorene enhances the
+dispersion interaction between phosphorene and HP35. Thus, oxidation enhances
+the destructive effect of phosphorene on the structure of HP35. These findings
+might shed light on understanding the biological toxicity of PO nanosheets and
+would be helpful for the future potential biomedical applications of PO
+nanosheets, such as nanodrugs and antibacterial agents.",2110.11880v1
+2023-02-04,Distinct melting behaviour of partially oxidized Cu nanoparticles and nanowires,"While most of the experimental studies are dealing with partially oxidized
+metallic nanosolids, their behaviour is not well understood theoretically. To
+this end we utilized molecular dynamics simulation and charge-optimized
+many-body potential to probe melting of Cu nanoparticles and nanowires with and
+without a monolayer of Cu$_2$O as a shell. It is shown that partially oxidized
+nanosolids present a different melting behaviour than the widely accepted
+picture of melting, and especially different than surface melting. (i) For both
+types of nanosolids we observed inward diffusion of $\sim$40\% of atomic oxygen
+into the metallic core at room temperature. (ii) For the nanowire with oxide
+shell we observed a solid state phase transition in the Cu core that is not
+present for the case without the oxide. (iii) Prior to melting, the oxide shell
+shrinks, and this process continues after melting, to form a particulate oxide,
+for both types of nanosolids.",2302.02219v1
+2023-04-23,Third Harmonic Generation And Photoluminescence Measurements in Zinc Oxide And Aluminum doped Zinc Oxide Thin Films Grown by Atomic Layer Deposition,"Zinc Oxide is a thoroughly studied wide-bandgap semiconductor possessing
+excellent optical and electronic properties at room temperature. The renewed
+interest in this material has been generated by doping with various impurities
+in order to further enhance versatile optoelectronic responses for practical
+applications. Specifically, Aluminum-doped Zinc Oxide is an emerging
+transparent conducting oxide for photovoltaic applications. Here I propose to
+conduct a series of experimental studies on broadband optical nonlinearity as
+well as photoluminescence from Aluminum doped Zinc Oxide as a function of
+Aluminum doping. The results of this study include studies including 1) Bandgap
+measurements 2) wavelength-dependent third harmonic generation and 3)
+one-photon-induced Photoluminescence. The most notable result is a multifold
+enhanced third-order nonlinear optical response from weakly doped Aluminum
+doped Zinc Oxide (up to 4%) in comparison with the undoped counterpart. The
+observed nonlinear optical trend as a function of Aluminum doping is correlated
+to the modification of the corresponding band structure. The Aluminum doping
+effect is extensively investigated in the context of absorption and
+Photoluminescence.",2304.11724v1
+2023-06-30,Substrate suppression of oxidation process in pnictogen monolayers,"2D materials present an interesting platform for device designs. However,
+oxidation can drastically change the system's properties, which need to be
+accounted for. Through {\it ab initio} calculations, we investigated
+freestanding and SiC-supported As, Sb, and Bi mono-elemental layers. The
+oxidation process occurs through an O$_2$ spin-state transition, accounted for
+within the Landau-Zener transition. Additionally, we have investigated the
+oxidation barriers and the role of spin-orbit coupling. Our calculations
+pointed out that the presence of SiC substrate reduces the oxidation time scale
+compared to a freestanding monolayer. We have extracted the energy barrier
+transition, compatible with our spin-transition analysis. Besides, spin-orbit
+coupling is relevant to the oxidation mechanisms and alters time scales. The
+energy barriers decrease as the pnictogen changes from As to Sb to Bi for the
+freestanding systems, while for SiC-supported, they increase across the
+pnictogen family. Our computed energy barriers confirm the enhanced robustness
+against oxidation for the SiC-supported systems.",2307.00138v1
+2011-04-18,Self-limited oxide formation in Ni(111) oxidation,"The oxidation of the Ni(111) surface is studied experimentally with low
+energy electron microscopy and theoretically by calculating the electron
+reflectivity for realistic models of the NiO/Ni(111) surface with an ab-initio
+scattering theory. Oxygen exposure at 300 K under ultrahigh-vacuum conditions
+leads to the formation of a continuous NiO(111)-like film consisting of
+nanosized domains. At 750 K, we observe the formation of a nano-heterogeneous
+film composed primarily of NiO(111)-like surface oxide nuclei, which exhibit
+virtually the same energy-dependent reflectivity as in the case of 300 K and
+which are separated by oxygen-free Ni(111) terraces. The scattering theory
+explains the observed normal incidence reflectivity R(E) of both the clean and
+the oxidized Ni(111) surface. At low energies R(E) of the oxidized surface is
+determined by a forbidden gap in the k_parallel=0 projected energy spectrum of
+the bulk NiO crystal. However, for both low and high temperature oxidation a
+rapid decrease of the reflectivity in approaching zero kinetic energy is
+experimentally observed. This feature is shown to characterize the thickness of
+the oxide layer, suggesting an average oxide thickness of two NiO layers.",1104.3481v2
+2018-04-12,Pt$_3$Zr(0001): A substrate for growing well-ordered ultrathin zirconia films by oxidation,"We have studied the surface of pure and oxidized Pt$_3$Zr(0001) by scanning
+tunneling microscopy (STM), Auger electron microscopy, and density functional
+theory (DFT). The well-annealed alloy surface shows perfect long-range chemical
+order. Occasional domain boundaries are probably caused by nonstoichiometry.
+Pt$_3$Zr exhibits ABAC stacking along [0001]; only the A-terminated surfaces
+are seen by STM, in agreement with DFT results showing a lower surface energy
+for the A termination. DFT further predicts a stronger inward relaxation of the
+surface Zr than for Pt, in spite of the larger atomic size of Zr. A closed
+ZrO$_2$ film is obtained by oxidation in $10^{-7}$ mbar O$_2$ at 400 $^\circ$C
+and post-annealing at $\approx 800 ^\circ$C. The oxide consists of an O-Zr-O
+trilayer, equivalent to a (111) trilayer of the fluorite structure of cubic
+ZrO$_2$, but contracted laterally. The oxide forms a $(\sqrt{19} \times
+\sqrt{19})$R23$^\circ$ superstructure. The first monolayer of the substrate
+consists of Pt and contracts, similar to the metastable reconstruction of pure
+Pt(111). DFT calculations show that the oxide trilayer binds rather weakly to
+the substrate. In spite of the O-terminated oxide, bonding to the substrate
+mainly occurs via the Zr atoms in the oxide, which strongly buckle down towards
+the Pt substrate atoms, if near a Pt position. According to DFT, the oxide has
+a bandgap; STM indicates that the conduction band minimum lies $\approx 2.3$ eV
+above $E_\mathrm{F}$.",1804.04405v1
+2018-04-24,Elucidation of the atomic-scale mechanism of the anisotropic oxidation rate of 4H-SiC between the ($0001$) Si-face and ($000\overline{1}$) C-face by using a new Si-O-C interatomic potential,"Silicon carbide (SiC) is an attractive semiconductor material for
+applications in power electronic devices. However, fabrication of a
+high-quality SiC/SiO${}_2$ interface has been a challenge. It is well-known
+that there is a great difference in oxidation rate between the Si-face and
+C-face, and that the quality of oxide on the Si-face is greater than that on
+the C-face. However, the atomistic mechanism of the thermal oxidation of SiC
+remains to be solved. In this paper, a new Si-C-O interatomic potential was
+developed to reproduce the kinetics of the thermal oxidation of SiC. Using this
+newly developed potential, large-scale SiC oxidation simulations at various
+temperature were performed. The results showed that the activation energy of
+the Si-face is much larger than that of the C-face. In the case of the Si-face,
+a flat and aligned interface structure including Si${}^{1+}$ was created. Based
+on the estimated activation energies of the intermediate oxide states, it is
+proposed that the stability of the flat interface structure is the origin of
+the high activation energy of the oxidation of the Si-face. In contrast, in the
+case of the C-face, it is found that the Si atom at the interface are easily
+pulled up by the O atoms. This process generates the disordered interface and
+decreases the activation energy of the oxidation. It is also proposed that many
+excess C atoms are created in the case of the C-face.",1804.08860v1
+2013-09-09,High-Mobility Two-Dimensional Electron Gases at Oxide Interfaces: Origins and Opportunities,"The discovery of two-dimensional electron gas (2DEG) at well-defined
+interfaces between insulating complex oxides provides the opportunity for a new
+generation of all-oxide electronics. Particularly, the 2DEG at the interface
+between two perovskite insulators represented by the formula of ABO3, such as
+LaAlO3 and SrTiO3, has attracted significant attention. In recent years,
+progresses have been made to decipher the puzzle of the origin of interface
+conduction, to design new types of oxide interfaces, and to improve the
+interfacial carrier mobility significantly. These achievements open the door to
+explore fundamental as well as applied physics of complex oxides. Here, we
+review our recent experimental work on metallic and insulating interfaces
+controlled by interfacial redox reactions in SrTiO3-based heterostructures. Due
+to the presence of oxygen-vacancies at the SrTiO3 surface, metallic conduction
+can be created at room temperature in perovskite-type interfaces when the
+overlayer oxide ABO3 involves Al, Ti, Zr, or Hf elements at the B-sites.
+Furthermore, relying on interface-stabilized oxygen vacancies, we have created
+a new type of 2DEG at the heterointerface between SrTiO3 and a spinel
+{\gamma}-Al2O3 epitaxial film with compatible oxygen ions sublattices. The
+spinel/perovskite oxide 2DEG exhibits an electron mobility exceeding 100,000
+cm2V-1s-1, more than one order of magnitude higher than those of hitherto
+investigated perovskite-type interfaces. Our findings pave the way for design
+of high-mobility all-oxide electronic devices and open a route towards studies
+of mesoscopic physics with complex oxides.",1309.2124v1
+2019-08-07,Part I: Theoretical Predictions of Preferential Oxidation in Refractory High Entropy Materials,"High entropy materials, which include high entropy alloys, carbides, and
+borides, are a topic of substantial research interest due to the possibility of
+a large number of new material compositions that could fill gaps in application
+needs. There is a current need for materials exhibiting high temperature
+stability, particularly oxidation resistance. A systematic understanding of the
+oxidation behavior in high entropy materials is therefore required. Prior work
+notes large differences in the thermodynamic favorability between oxides formed
+upon oxidation of high entropy materials. This work uses both analytical and
+computational thermodynamic approaches to investigate and quantify the effects
+of this large variation and the resulting potential for preferential component
+oxidation in refractory high entropy materials including group IV-, V- and
+VI-element based alloys and ceramics. Thermodynamic calculations show that a
+large tendency towards preferential oxidation is expected in these materials,
+even for elements whose oxides exhibit a small difference in thermodynamic
+favorability. The effect is reduced in carbides, compared to their alloy
+counterparts. Further, preferential oxidation in high entropy refractory
+materials could result in possible destabilization of the solid solution or
+formation of other, competing phases, with corresponding changes in bulk
+material properties.",1908.02654v2
+2022-02-08,Kinetic Monte Carlo Modelling of Nano-oxide Precipitation and its Associated Stability under Neutron Irradiation for the Fe-Ti-Y-O system,"While developing nuclear materials, predicting their behavior under long-term
+irradiation regimes spanning decades poses a significant challenge. We
+developed a novel Kinetic Monte Carlo (KMC) model to explore the precipitation
+behavior of Y-Ti-O oxides along grain boundaries within nanostructured ferritic
+alloys (NFA). This model also assessed the response of the oxides to neutron
+irradiation, even up simulated radiation damage levels in the desired long dpa
+range for reactor components. Our simulations investigated how temperature and
+grain boundary sinks influenced the oxide characteristics of a 12YWT-like alloy
+during heat treatments at 1023 K, 1123 K, and 1223 K. The oxide characteristics
+observed in our simulations were in good agreement with existing literature.
+Furthermore, the impact of grain boundaries on precipitation was found to be
+minimal. The resulting oxide configurations and positions were used in
+subsequent simulations that exposed them to simulated neutron irradiation to a
+total accumulated dose of 8 dpa at three temperatures: 673 K, 773 K, and 873 K,
+and at dose rates of 10^(-3), 10^(-4), and 10^(-5) dpa/s. This demonstrated the
+expected inverse relationship between oxide size and dose rate. In a long-term
+irradiation simulation at 873 K and 10^(-3) dpa/s was taken out to 66 dpa and
+found the oxides in the vicinity of the grain boundary were more susceptible to
+dissolution. Additionally, we conducted irradiation simulations of a 14YWT-like
+alloy to reproduce findings from neutron irradiation experiments. The larger
+oxides in the 14YWT-like alloy did not dissolve and displayed stability similar
+to the experimental results.",2202.03641v3
+2023-10-09,Detecting Iron Oxidation States in Liquids with the VOXES Bragg Spectrometer,"Determining the oxidation states of metals assumes great importance in
+various applications because a variation in the oxidation number can
+drastically influence the material properties. As an example, this becomes
+evident in edible liquids like wine and oil, where a change in the oxidation
+states of the contained metals can significantly modify both the overall
+quality and taste. To this end, here we present the MITIQO project, which aims
+to identify oxidation states of metals in edible liquids utilizing X-ray
+emission with Bragg spectroscopy. This is achieved using the VOXES crystal
+spectrometer, developed at INFN National Laboratories of Frascati (LNF),
+employing mosaic crystal (HAPG) in the Von Hamos configuration. This
+combination allow us to work with effective source sizes of up to a few
+millimeters and improves the typical low efficiency of Bragg spectroscopy, a
+crucial aspect when studying liquids with low metal concentration. Here we
+showcase the concept behind MITIQO, for a liquid solution containing oxidized
+iron. We performed several high-resolution emission spectra measurements, for
+the liquid and for different powdered samples containing oxidized and pure
+iron. By looking at the spectral features of the iron's K$\beta$ emission
+lineshape, we were able to obtain, for a liquid, a result consistent with the
+oxidized iron powders and successfully quantifying the effect of oxidation.",2310.06062v1
+1997-07-11,Intermediate Valence Model for the Colossal Magnetoresistance in Tl_{2}Mn_{2}O_{7},"The colossal magnetoresistance exhibited by Tl_{2}Mn_{2}O_{7} is an
+interesting phenomenon, as it is very similar to that found in perovskite
+manganese oxides although the compound differs both in its crystalline
+structure and electronic properties from the manganites. At the same time,
+other pyrochlore compounds, though sharing the same structure with
+Tl_{2}Mn_{2}O_{7}, do not exhibit the strong coupling between magnetism and
+transport properties found in this material. Mostly due to the absence of
+evidence for significant doping into the Mn-O sublattice, and the tendency of
+Tl to form conduction bands, the traditional double exchange mechanism
+mentioned in connection with manganites does not seem suitable to explain the
+experimental results in this case. We propose a model for Tl_{2}Mn_{2}O_{7}
+consisting of a lattice of intermediate valence ions fluctuating between two
+magnetic configurations, representing Mn-3d orbitals, hybridized with a
+conduction band, which we associate with Tl. This model had been proposed
+originally for the analysis of intermediate valence Tm compounds. With a
+simplified treatment of the model we obtain the electronic structure and
+transport properties of Tl_{2}Mn_{2}O_{7}, with good qualitative agreement to
+experiments. The presence of a hybridization gap in the density of states seems
+important to understand the reported Hall data.",9707130v2
+1999-02-17,Quantum Monte Carlo Study of Weakly Coupled Spin Ladders,"We report a quantum Monte Carlo study of the thermodynamic properties of
+arrays of spin ladders with various widths ($n$), coupled via a weak
+inter-ladder exchange coupling $\alpha J$, where $J$ is the intra-ladder
+coupling both along and between the chains. This coupled ladder system serves
+as a simplified model for the magnetism of presumed ordered spin and charge
+stripes in the two-dimensional CuO$_2$ planes of hole-doped copper oxides. Our
+results for $n=3$ with weak inter-ladder coupling $\alpha=0.05$, estimated from
+the $t-t'-t''-J$ model, show good agreement with the ordering temperature of
+the recently observed spin density wave condensation in La$_2$CuO$_{4+y}$. We
+show that there exists a quantum critical point at $\alpha_c \simeq 0.07$ for
+$n=4$, and determine the phase diagram. Our data at this quantum critical point
+agree quantitatively with the universal scaling predicted by the quantum
+nonlinear $\sigma$ model. We also report results on random mixtures of $n=2$
+and $n=3$ ladders, which correspond to the doping region near but above 1/8.
+Our study on the magnetic static structure factor reveals a saturation of the
+incommensurability of the spin correlations around 1/8, while the
+incommensurability of the charge stripes grows linearly with hole
+concentration. The implications of this result for the interpretation of
+neutron scattering experiments on the dynamic spin fluctuations in
+La$_{2-x}$Sr$_x$CuO$_4$ are discussed.",9902248v1
+2000-11-28,Tunneling conductance of SIN junctions with different gap symmetries and non-magnetic impurities by direct solution of real-axis Eliashberg equations,"We theoretically investigate the effect of various symmetries of the
+superconducting order parameter Delta(omega) on the normalized tunneling
+conductance of SIN junctions by directly solving the real-axis Eliashberg
+equations (EEs) for a half-filled infinite band, with the simplifying
+assumption mu*=0. We analyze six different symmetries of the order parameter:
+s, d, s+id, s+d, extended s and anisotropic s, by assuming that the spectral
+function alpha^{2}F(Omega) contains an isotropic part alpha^{2}F(Omega)_{is}
+and an anisotropic one, alpha^{2}F(Omega)_{an}, such that
+alpha^{2}F(Omega)_{an} = g alpha^{2}F(Omega)_{is}, where g is a constant.
+  We compare the resulting conductance curves at T=2 K to those obtained by
+analytical continuation of the imaginary-axis solution of the EEs, and we show
+that the agreement is not equally good for all symmetries. Then, we discuss the
+effect of non-magnetic impurities on the theoretical tunneling conductance
+curves at T=4 K for all the symmetries considered.
+  Finally, as an example, we apply our calculations to the case of
+optimally-doped high-T_{c} superconductors (HTSC). Surprisingly, although the
+possibility of explaining the very complex phenomenology of HTSC is probably
+beyond the limits of the Eliashberg theory, the comparison of the theoretical
+curves calculated at T=4 K with the experimental ones obtained in various
+optimally-doped copper-oxides gives fairly good results.",0011472v3
+2000-12-01,Magnetic and orbital ordering in cuprates and manganites,"The mechanisms of magnetic and orbital interactions due to double exchange
+(DE) and superexchange (SE) in transition metal oxides with degenerate e_g
+orbitals are presented. Specifically, we study the effective spin-orbital
+models derived for the d^9 ions as in KCuF_3, and for the d^4 ions as in
+LaMnO_3, for spins S=1/2 and S=2, respectively. Such models are characterized
+by three types of elementary excitations: spin waves, orbital waves, and
+spin-and-orbital waves. The SE interactions between Cu^{2+} (d^9) ions are
+inherently frustrated, which leads to a new mechanism of spin liquid which
+operates in three dimensions. The SE between Mn^{3+} (d^4) ions explains the
+A-type antiferromagnetic order in LaMnO_3 which coexists with the orbital
+order. In contrast, the ferromagnetic metallic phase and isotropic spin waves
+observed in doped manganites are explained by DE for degenerate e_g orbitals.
+It is shown that although a hole does not couple to spin excitations in
+ferromagnetic planes of LaMnO_3, the orbital excitations change the energy
+scale for the coherent hole propagation and cause a large redistribution of
+spectral weight. Finally, we point out some open problems in the present
+understanding of doped manganites.",0012013v1
+2001-04-09,Enhancement of the high-field critical current density of superconducting MgB2 by proton irradiation,"A relatively high critical temperature, Tc, approaching 40 K, places the
+recently-discovered superconductor magnesium diboride (MgB2) intermediate
+between the families of low- and copper-oxide-based high-temperature
+superconductors (HTS). Supercurrent flow in MgB2 is unhindered by grain
+boundaries, unlike the HTS materials. Thus, long polycrystalline MgB2
+conductors may be easier to fabricate, and so could fill a potentially
+important niche of applications in the 20 to 30 K temperature range. However,
+one disadvantage of MgB2 is that in bulk material the critical current density,
+Jc, appears to drop more rapidly with increasing magnetic field than it does in
+the HTS phases. The magnitude and field dependence of Jc are related to the
+presence of structural defects that can ""pin"" the quantised magnetic vortices
+that permeate the material, and prevent them from moving under the action of
+the Lorentz force. Vortex studies suggest that it is the paucity of suitable
+defects in MgB2 that causes the rapid decay of Jc with field. Here we show that
+modest levels of atomic disorder, induced by proton irradiation, enhance the
+pinning, and so increase Jc significantly at high fields. We anticipate that
+chemical doping or mechanical processing should be capable of generating
+similar levels of disorder, and so achieve technologically-attractive
+performance in MgB2 by economically-viable routes.",0104156v2
+2002-09-14,"Magnon-polaron and Spin-polaron Signatures in the Specific Heat and Electrical Resistivity of $La_{0.6}Y_{0.1}Ca_{0.3}MnO_3$ in Zero Magnetic Field, and the Effect of $Mn-O-Mn$ Bond Environment","$La_{0.6}Y_{0.1}Ca_{0.3}MnO_{3}$, an $ABO_{3}$ perovskite manganite oxide,
+exhibits a non trivial behavior in the vicinity of the sharp peak found in the
+resistivity $\rho$ as a function of temperature $T$ in zero magnetic field. The
+various features seen on $d\rho/dT$ are discussed in terms of competing phase
+transitions. They are related to the $Mn-O-Mn$ bond environment depending on
+the content of the $A$ crystallographic site. A Ginzburg-Landau type theory is
+presented for incorporating concurrent phase transitions. The specific heat $C$
+of such a compound is also examined from 50 till 200 K. A log-log analysis
+indicates different regimes. In the low temperature conducting ferromagnetic
+phase, a collective magnon signature ($C \simeq T^{3/2}$) is found as for what
+are called magnon-polaron excitations. A $C \simeq T^{2/3}$ law is found at
+high temperature and discussed in terms of the fractal dimension of the
+conducting network of the weakly conducting (so-called insulating) phase and
+Orbach estimate of the excitation spectral behaviors. The need of considering
+both independent spin scattering and collective spin scattering is thus
+emphasized. The report indicates a remarkable agreement for the Fisher-Langer
+formula, i.e. $C$ $\sim$ $d\rho/dT$ at second order phase transitions. Within
+the Attfield model, we find an inverse square root relationship between the
+critical temperature(s) and the total local $Mn-O-Mn$ strain.",0209340v1
+2004-05-26,Microwave Magnetoelectric Effects in Single Crystal Bilayers of Yttrium Iron Garnet and Lead Magnesium Niobate-Lead Titanate,"The first observation of microwave magnetoelectric (ME) interactions through
+ferromagnetic resonance (FMR) in bilayers of single crystal
+ferromagnetic-piezoelectric oxides and a theoretical model for the effect are
+presented. An electric field E produces a mechanical deformation in the
+piezoelectric phase, resulting in a shift dHE in the resonance field for the
+ferromagnet. The strength of ME coupling is obtained from data on dHE vs E.
+Studies were performed at 9.3 GHz on bilayers of (111) yttrium iron garnet
+(YIG) films and (001) lead magnesium niobate-lead titanate (PMN-PT). The
+samples were positioned outside a TE102-reflection type cavity. Resonance
+profiles were obtained for E = 0-8 kV/cm for both in-plane and out-of-plane
+magnetic fields H. Important results are as follows. (i) The ME coupling in the
+bilayers is an order of magnitude stronger than in polycrystalline composites
+and is in the range 1-5.4 Oe cm/kOe, depending on the YIG film thickness. (ii)
+The coupling strength is dependent on the magnetic field orientation and is
+higher for out-of-plane H than for in-plane H. (iii) Estimated ME constant and
+its dependence on volume ratio for the two phases are in good agreement with
+the data.",0405622v1
+2005-03-31,Synthesis and characterization of Na03RhO206H2O - a semiconductor with a weak ferromagnetic component,"We have prepared the oxyhydrate Na03RhO206H2O by extracting Na+ cations from
+NaRhO2 and intercalating water molecules using an aqueous solution of Na2S2O8.
+Synchrotron X-ray powder diffraction, thermogravimetric analysis (TGA), and
+energy-dispersive x-ray analysis (EDX) reveal that a non-stoichiometric
+Na03(H2O)06 network separates layers of edge-sharing RhO6 octahedra containing
+Rh3+(4d6, S=0) and Rh4+ (4d5, S=1/2). The resistivities of NaRhO2 and
+Na03RhO206H2O (T < 300) reveal insulating and semi-conducting behavior with
+activation gaps of 134 meV and 7.8 meV, respectively. Both Na03RhO206H2O and
+NaRhO2 show paramagnetism at room temperature, however, the sodium-deficient
+sample exhibits simultaneously a weak but experimentally reproducible
+ferromagnetic component. Both samples exhibit a temperature-independent Pauli
+paramagnetism, for NaRhO2 at T > 50 K and for Na03RhO206H2O at T > 25 K. The
+relative magnitudes of the temperature-independent magnetic susceptibilities,
+that of the oxide sample being half that of the oxyhydrate, is consistent with
+a higher density of thermally accessible electron states at the Fermi level in
+the hydrated sample. At low temperatures the magnetic moments rise sharply,
+providing evidence of localized and weakl -ordered electronic spins.",0504007v1
+2005-05-04,From Finite-Size and Surface Effects to Glassy Behaviour in Ferrimagnetic Nanoparticles,"This chapter is aimed at studying the anomalous magnetic properties (glassy
+behaviour) observed at low temperatures in nanoparticles of ferrimagnetic
+oxides. This topic is discussed both from numerical results and experimental
+data. Ferrimagnetic fine particles show most of the features of glassy systems
+due to the random distribution of anisotropy axis, interparticle interactions
+and surface effects. Experiments have shown that the hysteresis loops display
+high closure fields with high values of the differential susceptibility. Low
+magnetisation as compared to bulk, shifted loops after field-cooling, highfield
+irreversibilities between zero-field and field cooling processes and ageing
+phenomena in the time-dependence of the magnetisation, are also observed. This
+phenomenology indicates the existence of some kind of freezing phenomenon
+arising from a complex hierarchy of the energy levels, whose origin is
+currently under discussion. Two models have been proposed to account for it: i)
+the existence of a spin-glass state at the surface of the particle which is
+coupled to the particle core through an exchange field; and ii) the collective
+behaviour induced by interparticle interactions. In real systems, both
+contributions simultaneously occur, being difficult to distinguish their
+effects. In contrast, numerical simulations allow us to build a model just
+containing the essential ingredients to study solely one of two phenomena.",0505112v1
+2005-07-05,Valence instability of cerium under pressure in the Kondo-like perovskite La$_{0.1}$Ce$_{0.4}$Sr$_{0.5}$MnO$_3$,"Effect of hydrostatic pressure and magnetic field on electrical resistance of
+the Kondo-like perovskite manganese oxide,
+La$_{0.1}$Ce$_{0.4}$Sr$_{0.5}$MnO$_3$ with a ferrimagnetic ground state, have
+been investigated up to 2.1 GPa and 9 T. In this compound, the Mn-moments
+undergo double exchange mediated ferromagnetic ordering at $T_{\rm C}$ $\sim$
+280 K and there is a resistance maximum, $T_{\rm max}$ at about 130 K which is
+correlated with an antiferromagnetic ordering of {\it cerium} with respect to
+the Mn-sublattice moments. Under pressure, the $T_{\rm max}$ shifts to lower
+temperature at a rate of d$T_{max}$/d$P$ = -162 K/GPa and disappears at a
+critical pressure $P_{\rm c}$ $\sim$ 0.9 GPa. Further, the coefficient, $m$ of
+$-logT$ term due to Kondo scattering decreases linearly with increase of
+pressure showing an inflection point in the vicinity of $P_{\rm c}$. These
+results suggest that {\it cerium} undergoes a transition from Ce$^{3+}$ state
+to Ce$^{4+}$/Ce$^{3+}$ mixed valence state under pressure. In contrast to
+pressure effect, the applied magnetic field shifts $T_{\rm max}$ to higher
+temperature presumably due to enhanced ferromagnetic Mn moments.",0507094v1
+2007-01-17,Heisenberg exchange in magnetic monoxides,"The superexchange intertacion in transition-metal oxides, proposed initially
+by Anderson in 1950, is treated using contemporary tight-binding theory and
+existing parameters. We find also a direct exchange for nearest-neighbor metal
+ions, larger by a factor of order five than the superexchange. This direct
+exchange arises from Vddm coupling, rather than overlap of atomic charge
+densities, a small overlap exchange contribution which we also estimate. For
+FeO and CoO there is also an important negative contribution, related to Stoner
+ferromagnetism, from the partially filled minority-spin band which broadens
+when ionic spins are aligned. The corresponding J1 and J2 parameters are
+calculated for MnO, FeO, CoO, and NiO. They give good accounts of the Neel and
+the Curie-Weiss temperatures, show appropriate trends, and give a reasonable
+account of their volume dependences. For MnO the predicted value for the
+magnetic susceptibility at the Neel temperature and the crystal distortion
+arising from the antiferromagnetic transition were reasonably well given.
+Application to CuO2 planes in the cuprates gives J=1220oK, compared to an
+experimental 1500oK, and for LiCrO2 gives J1=4 50oK compared to an experimental
+230oK.",0701423v3
+2007-08-17,Quantum spin correlations through the superconducting-normal phase transition in electron-doped superconducting Pr0.88LaCe0.12CuO4-d,"The quantum spin fluctuations of the S = 1/2 Cu ions are important in
+determining the physical properties of the high-transition temperature
+(high-Tc) copper oxide superconductors, but their possible role in the electron
+pairing for superconductivity remains an open question. The principal feature
+of the spin fluctuations in optimally doped high-Tc superconductors is a well
+defined magnetic resonance whose energy (Er) tracks Tc (as the composition is
+varied) and whose intensity develops like an order parameter in the
+superconducting state. We show that the suppression of superconductivity and
+its associated condensation energy by a magnetic field in the electron-doped
+high-Tc superconductor, Pr0.88LaCe0.12CuO4-d (Tc = 24 K), is accompanied by the
+complete suppression of the resonance and the concomitant emergence of static
+antiferromagnetic (AF) order. Our results demonstrate that the resonance is
+intimately related to the superconducting condensation energy, and thus suggest
+that it plays a role in the electron pairing and superconductivity.",0708.2326v1
+2008-03-25,"Structural and Magnetic Properties of Pyrochlore Solid Solutions (Y,Lu)2Ti2-x(Nb,Ta)xO7+/-y","The synthesis and characterization of the pyrochlore solid solutions,
+Y2Ti2-xNbxO7-y, Lu2Ti2-xNbxO7-y, Y2Ti2-xTaxO7-y and Lu2TiTaO7-y (-0.4<y<0.5),
+is described. Synthesis at 1600 C, and 10-5 Torr yields oxygen deficiency in
+all systems. All compounds are found to be paramagnetic and semiconducting,
+with the size of the local moments being less, in some cases substantially
+less, than the expected value for the number of nominally unpaired electrons
+present. Thermogravimetric analysis (TGA) shows that all compounds can be fully
+oxidized while retaining the pyrochlore structure, yielding oxygen rich
+pyrochlores as white powders. Powder neutron diffraction of Y2TiNbO7-based
+samples was done. Refinement of the data for oxygen deficient Y2TiNbO6.76
+indicates the presence of a distribution of oxygen over the 8b and 48f sites.
+Refinement of the data for oxygen rich Y2TiNbO7.5 shows these sites to be
+completely filled, with an additional half filling of the 8a site. The magnetic
+and TGA data strongly suggest a preference for a Ti3+/(Nb,Ta)5+ combination, as
+opposed to Ti4+/(Nb,Ta)4+, in this pyrochlore family. In addition, the evidence
+clearly points to Ti3+ as the source of the localized moments, with no evidence
+for localized Nb4+ moments.",0803.3568v1
+2008-06-17,Superconductivity in Silicon Nanostructures,"We present the findings of the superconductivity in the silicon
+nanostructures prepared by short time diffusion of boron after preliminary
+oxidation of the n-type Si (100) surface. These Si-based nanostructures
+represent the p-type high mobility silicon quantum well (Si-QW) confined by the
+delta - barriers heavily doped with boron. The ESR studies show that the delta
+- barriers appear to consist of the trigonal dipole centers, B(+)-B(-), which
+are caused by the negative-U reconstruction of the shallow boron acceptors,
+2B(0)=>B(+)-B(-). The temperature and magnetic field dependencies of the
+resistance, thermo-emf, specific heat and magnetic susceptibility demonstrate
+that the high temperature superconductivity observed seems to result from the
+transfer of the small hole bipolarons through these negative-U dipole centers
+of boron at the Si-QW - delta - barrier interfaces. The value of the
+superconductor energy gap obtained is in a good agreement with the data derived
+from the oscillations of the conductance in normal state and of the
+zero-resistance supercurrent in superconductor state as a function of the bias
+voltage. These oscillations appear to be correlated by on- and off-resonance
+tuning the two-dimensional subbands of holes with the Fermi energy in the
+superconductor delta - barriers. Finally, the proximity effect in the S- Si-QW
+-S structure is revealed by the findings of the multiple Andreev reflection
+(MAR) processes and the quantization of the supercurrent.",0806.2800v1
+2010-04-04,"Adsorption of molecular oxygen on doped graphene: atomic, electronic and magnetic properties","Adsorption of molecular oxygen on B-, N-, Al-, Si-, P-, Cr- and Mn-doped
+graphene is theoretically studied using density functional theory in order to
+clarify if O2 can change the possibility of using doped graphene for gas
+sensors, electronic and spintronic devices. O2 is physisorbed on B-, and Ndoped
+graphene with small adsorption energy and long distance from the graphene
+plane, indicating the oxidation will not happen; chemisorption is observed on
+Al-, Si-, P-, Cr- and Mn-doped graphene. The local curvature caused by the
+large bond length of X-C (X represents the dopants) relative to CC bond plays a
+very important role in this chemisorption. The chemisorption of O2 induces
+dramatic changes of electronic structures and localized spin polarization of
+doped graphene, and in particular, chemisorption of O2 on Cr-doped graphene is
+antiferromagnetic. The analysis of electronic density of states shows the
+contribution of the hybridization between O and dopants is mainly from the p or
+d orbitals. Furthermore, spin density shows that the magnetization locates
+mainly around the doped atoms, which may be responsible for the Kondo effect.
+These special properties supply a good choice to control the electronic
+properties and spin polarization in the field of graphene engineering.",1004.0518v2
+2010-07-01,Electric-Field-control of spin rotation in bilayer graphene,"The manipulation of the electron spin degree of freedom is at the core of the
+spintronics paradigm, which offers the perspective of reduced power
+consumption, enabled by the decoupling of information processing from net
+charge transfer. Spintronics also offers the possibility of devising hybrid
+devices able to perform logic, communication, and storage operations. Graphene,
+with its potentially long spin-coherence length, is a promising material for
+spin-encoded information transport. However, the small spin-orbit interaction
+is also a limitation for the design of conventional devices based on the
+canonical Datta-Das spin-FET. An alternative solution can be found in magnetic
+doping of graphene, or, as discussed in the present work, in exploiting the
+proximity effect between graphene and Ferromagnetic Oxides (FOs). Graphene in
+proximity to FO experiences an exchange proximity interaction (EPI), that acts
+as an effective Zeeman field for electrons in graphene, inducing a spin
+precession around the magnetization axis of the FO. Here we show that in an
+appropriately designed double-gate field-effect transistor, with a bilayer
+graphene channel and FO used as a gate dielectric, spin-precession of carriers
+can be turned ON and OFF with the application of a differential voltage to the
+gates. This feature is directly probed in the spin-resolved conductance of the
+bilayer.",1007.0091v1
+2010-10-14,Growth mechanism of nanostructured superparamagnetic rods obtained by electrostatic co-assembly,"We report on the growth of nanostructured rods fabricated by electrostatic
+co-assembly between iron oxide nanoparticles and polymers. The nanoparticles
+put under scrutiny, {\gamma}-Fe2O3 or maghemite, have diameter of 6.7 nm and
+8.3 nm and narrow polydispersity. The co-assembly is driven by i) the
+electrostatic interactions between the polymers and the particles, and by ii)
+the presence of an externally applied magnetic field. The rods are
+characterized by large anisotropy factors, with diameter 200 nm and length
+comprised between 1 and 100 {\mu}m. In the present work, we provide for the
+first time the morphology diagram for the rods as a function of ionic strength
+and concentration. We show the existence of a critical nanoparticle
+concentration and of a critical ionic strength beyond which the rods do not
+form. In the intermediate regimes, only tortuous and branched aggregates are
+detected. At higher concentrations and lower ionic strengths, linear and stiff
+rods with superparamagnetic properties are produced. Based on these data, a
+mechanism for the rod formation is proposed. The mechanism proceeds in two
+steps : the formation and growth of spherical clusters of particles, and the
+alignment of the clusters induced by the magnetic dipolar interactions. As far
+as the kinetics of these processes is concerned, the clusters growth and their
+alignment occur concomitantly, leading to a continuous accretion of particles
+or small clusters, and a welding of the rodlike structure.",1010.2852v1
+2011-01-06,Quantum phase transitions in a strongly entangled spin-orbital chain: A field-theoretical approach,"Motivated by recent experiments on quasi-1D vanadium oxides, we study quantum
+phase transitions in a one-dimensional spin-orbital model describing a Haldane
+chain and a classical Ising chain locally coupled by the relativistic
+spin-orbit interaction. By employing a field-theoretical approach, we analyze
+the topology of the ground-state phase diagram and identify the nature of the
+phase transitions. In the strong coupling limit, a long-range N\'eel order of
+entangled spin and orbital angular momentum appears in the ground state. We
+find that, depending on the relative scales of the spin and orbital gaps, the
+linear chain follows two distinct routes to reach the N\'eel state. First, when
+the orbital exchange is the dominating energy scale, a two-stage ordering takes
+place in which the magnetic transition is followed by melting of the orbital
+Ising order; both transitions belong to the two-dimensional Ising universality
+class. In the opposite limit, the low-energy orbital modes undergo a continuous
+reordering transition which represents a line of Gaussian critical points. On
+this line the orbital degrees of freedom form a Tomonaga-Luttinger liquid. We
+argue that the emergence of the Gaussian criticality results from merging of
+the two Ising transitions in the strong hybridization region where the
+characteristic spin and orbital energy scales become comparable. Finally, we
+show that, due to the spin-orbit coupling, an external magnetic field acting on
+the spins can induce an orbital Ising transition.",1101.1268v3
+2011-09-20,"Hybrid functional electronic structure of PbPdO$_2$, a small-gap semiconductor","PbPdO$_2$, a ternary compound containing the lone-pair active ion Pb$^{2+}$
+and the square-planar d$^8$ Pd$^{2+}$ ion, has attracted recent interest
+because of the suggestion that its electronic structure, calculated within
+density functional theory using either the local density or the generalized
+gradient approximations, displays zero-gap behavior. In light of the potential
+ease of doping magnetic ions in this structure, it has been suggested that the
+introduction of spin, in conjunction with zero band gap, can result in unusual
+magnetic ground states and unusual magnetotransport. It is known that most
+electronic structure calculations do not properly obtain a band gap even for
+the simple oxide PdO, and instead obtain a metal or a zero-gap semiconductor.
+Here we present density functional calculations employing a screened hybrid
+functional (HSE) which correctly obtain a band gap for the electronic structure
+of PdO. When employed to calculate the electronic ground state of PbPdO$_2$, a
+band gap is again obtained, which is consistent both with the experimental data
+on this compound, as well as a consideration of valence states and of
+metal-oxygen connectivity in the crystal structure. We also present comparisons
+of the absolute positions (relative to the vacuum level) of the conduction band
+minima and the valence band maxima in {\alpha}-PbO, PdO and PbPdO$_2$, which
+suggest ease of $p$-type doping in PbPdO$_2$ that has been observed even in
+nominally pure materials.",1109.4446v2
+2011-12-19,Quantum-Hall plateau-plateau transition in top-gated epitaxial graphene grown on SiC (0001),"We investigate the low-temperature magneto-transport properties of monolayer
+epitaxial graphene films formed on the Si-face of semi-insulating 4H-SiC
+substrates by a high temperature sublimation process. A high-k top-gate on the
+epitaxial graphene is realized by inserting a fully oxidized nanometer thin
+aluminum film as a seeding layer, followed by an atomic layer deposition
+process. At low temperatures, the devices demonstrate a strong field effect by
+the top gate with an on/off ratio of ~7 and an electron mobility up to ~3250
+cm^2/Vs. After the observation of the half-integer quantum Hall effect for
+monolayer epitaxial graphene films, detailed magneto-transport measurements
+have been carried out including varying densities, temperatures, magnetic
+fields and currents. We study the width of the distinguishable quantum-Hall
+plateau to plateau transition (Landau level index n=0 to n=1) as temperature
+(T) and current are varied. For both gate voltage and magnetic field sweeps and
+T>10 K the transition width goes as T^{-\kappa} with exponent \kappa ~0.42.
+This universal scaling exponent agrees well with those found in III-V
+heterojunctions with short range alloy disorders and in exfoliated graphene.",1112.4345v2
+2012-06-20,Ga$^{3+}$-substitution effects in the weak ferromagnetic oxide LaCo$_{0.8}$Rh$_{0.2}$O$_{3}$,"Magnetization and x-ray diffraction have been measured on polycrystalline
+samples of LaCo$_{0.8-y}$Rh$_{0.2}$Ga$_{y}$O$_{3}$ for $0 \leq y \leq 0.15$ in
+order to understand the spin state of Co$^{3+}$ through the Ga$^{3+}$
+substitution effect. The ferromagnetic order in LaCo$_{0.8}$Rh$_{0.2}$O$_{3}$
+below 15 K is dramatically suppressed by the Ga$^{3+}$ substitution, where the
+ferromagnetic volume fraction is linearly decreased. The normal state
+susceptibility also systematically decreases with the Ga content, from which we
+find that one Ga$^{3+}$ ion reduces 4.6 $\mu_{\rm B}$ per formula unit. We have
+evaluated how the concentration of the high-spin state Co$^{3+}$ changes with
+temperature by using an extended Curie-Weiss law, and have found that the
+substituted Rh$^{3+}$ ion stabilizes the high-spin state Co$^{3+}$ ion down to
+low temperatures. We find that Ga$^{3+}$ preferentially replaces the high-spin
+state Co$^{3+}$, which makes a remarkable contrast to our previous finding that
+Rh$^{3+}$ preferentially replaces the low-spin state Co$^{3+}$. These results
+strongly suggest that the magnetically excited state of LaCoO$_{3}$ at room
+temperature is a mixed state of high-spin state Co$^{3+}$ and low-spin state
+Co$^{3+}$.",1206.4472v1
+2013-02-15,Road to room-temperature superconductivity: A universal model,"In a semiclassical view superconductivity is attributed exclusively to the
+advance of atoms' outer s electrons through the nuclei of neighbor atoms in a
+solid. The necessary progression of holes in the opposite direction has the
+electric and magnetic effect as if two electrons were advancing instead of each
+actual one. Superconductivity ceases when the associated lateral oscillation of
+the outer s electrons extends between neighbor atoms. If such overswing occurs
+already at T = 0, then the material is a normal conductor. Otherwise, lateral
+overswing can be caused by lattice vibrations at a critical temperature Tc or
+by a critical magnetic field Bc. Lateral electron oscillations are reduced -
+and Tc is increased - when the atoms of the outer s electrons are squeezed, be
+it in the bulk crystal, in a thin film, or under external pressure on the
+sample. The model is applied to alkali metals and alkali-doped fullerenes.
+Aluminum serves as an example of a simple metal with superconductivity.
+Application of the model to transition metals, intertransitional alloys and
+compounds of transition metals with other elements sheds light on the pattern
+of their critical temperature. More examples of the squeeze effect are provided
+by the superconductivity of PdH, MgB2, borocarbides, ferropnictides, and
+organic charge-transfer salts. The model also provides the superconduction
+mechanism in the oxide superconductors, exemplified by YBa2Cu3O7. Finally the
+model suggests which steps to take in order to reach superconductivity at room
+temperature and above.",1302.5043v2
+2013-02-26,Colloidal Anisotropic ZnO-Fe@FexOy Nanoarchitectures with Interface-Mediated Exchange-Bias and Band-Edge Ultraviolet Fluorescence,"Hybrid nanocrystals (HNCs), based on ZnO nanorods (NRs) decorated with
+magnetic Fe-based domains, were synthesized via a colloidal seeded-growth
+method. The approach involved heterogeneous nucleation of Fe nanocrystals on
+size-tailored ZnO nanorod seeds in a noncoordinating solvent, followed by
+partial surface oxidation of the former to the corresponding Fe@FexOy
+core@shell domains. HNCs with variable population and size of the Fe-based
+nanodomains could be synthesized depending on the surface reactivity of the ZnO
+seeds. The structure-property relationships in these HNCs were carefully
+studied. In HNCs characterized by a large number of small Fe@FexOy core@shell
+nanodomains on the ZnO seed surface, the interfacial communication across the
+Fe-core and FexOy-shell generated a sizeable exchange-bias effect mediated by
+frozen interfacial spins. On the other hand, in HNCs carrying a lower density
+of comparatively larger Fe@FexOy domains, partial removal of the Fe core
+created an inner void in-between that led to suppressed exchange coupling
+anisotropy. As a further proof of functionality, the HNCs exhibited pronounced
+band-edge ultraviolet fluorescence. The latter was blue-shifted compared to the
+parent ZnO NRs, inferring coupling of the semiconductor and magnet sections.",1302.6347v1
+2013-03-05,Anomalous Transport in Sketched Nanostructures at the LaAlO3/SrTiO3 Interface,"The oxide heterostructure LaAlO3/SrTiO3 supports a two-dimensional electron
+liquid with a variety of competing phases including magnetism,
+superconductivity and weak antilocalization due to Rashba spin-orbit coupling.
+Further confinement of this 2D electron liquid to the quasi-one-dimensional
+regime can provide insight into the underlying physics of this system and
+reveal new behavior. Here we describe magnetotransport experiments on narrow
+LaAlO3/SrTiO3 structures created by a conductive atomic force microscope
+lithography technique. Four-terminal local transport measurements on
+~10-nm-wide Hall bar structures yield longitudinal resistances that are
+comparable to the resistance quantum h/e2 and independent of the channel
+length. Large nonlocal resistances (as large as 10^4 ohms) are observed in some
+but not all structures with separations between current and voltage that are
+large compared to the 2D mean-free path. The nonlocal transport is strongly
+suppressed by the onset of superconductivity below ~200 mK. The origin of these
+anomalous transport signatures is not understood, but may arise from coherent
+transport defined by strong spin-orbit coupling and/or magnetic interactions.",1303.1079v1
+2013-03-12,Démixtion et ségrégation superficielle dans les alliages fer-chrome,"Ferritic steels possibly strengthened by oxide dispersion are candidates as
+structural materials for generation IV and fusion nuclear reactors. Their use
+is limited by incomplete knowledge of the iron-chromium phase diagram at low
+temperatures and of the phenomena inducing preferential segregation of one
+element at grain boundaries or at surfaces. In this context, this work
+contributes to the multi-scale study of the model iron-chromium alloy and their
+free surfaces by numerical simulations. This study begins with ab initio
+calculations of properties related to the mixture of atoms of iron and
+chromium. We highlight complex dependency of the magnetic moments of the
+chromium atoms on their local chemical environment. Surface properties are also
+proving sensitive to magnetism. This is the case of impurity segregation of
+chromium in iron and of their interactions near the surface. In a second step,
+we construct a simple energy model for high numerical efficiency. It is based
+on pair interactions on a rigid lattice to which are given local chemical
+environment and temperature dependencies. With this model, we reproduce the ab
+initio results at zero temperature and experimental results at high
+temperature. We also deduce the solubility limits at all intermediate
+temperatures with mean field approximations that we compare to Monte Carlo
+simulations. The last step of our work is to introduce free surfaces in our
+model. We then study the effect of ab initio calculated bulk and surface
+properties on surface segregation. Finally, we calculate segregation isotherms.
+We therefore propose an evolution model of surface composition of iron-chromium
+alloys as a function of bulk composition.",1303.2938v1
+2013-11-03,Thickness-dependent ferromagnetic metal to paramagnetic insulator transition in La$_{0.6}$Sr$_{0.4}$MnO$_3$ thin films studied by x-ray magnetic circular dichroism,"Metallic transition-metal oxides undergo a metal-to-insulator transition
+(MIT) as the film thickness decreases across a ritical thickness of several
+monolayers (MLs), but its driving mechanism remains controversial. We have
+studied the thickness-dependent MIT of the ferromagnetic metal
+La$_{0.6}$Sr$_{0.4}$MnO$_3$ by x-ray absorption spectroscopy and x-ray magnetic
+circular dichroism. As the film thickness was decreased across the critical
+thickness of the MIT (6-8 ML), a gradual decrease of the ferromagnetic signals
+and a concomitant increase of paramagnetic signals were observed, while the Mn
+valence abruptly decreased towards Mn$^{3+}$. These observations suggest that
+the ferromagnetic phase gradually and most likely inhomogeneously turns into
+the paramagnetic phase and both phases abruptly become insulating at the
+critical thickness.",1311.0520v4
+2014-07-21,Direct epitaxial integration of the ferromagnetic semiconductor EuO with silicon for spintronic applications,"Materials in which charge and spin degrees of freedom interact strongly offer
+applications known as spintronics. Following a remarkable success of metallic
+spintronics based on the giant-magnetoresistive effect, tremendous efforts have
+been invested into the less developed semiconductor spintronics, in particular,
+with the aim to produce three-terminal spintronic devices, e.g. spin
+transistors. One of the most important prerequisites for such a technology is
+an effective injection of spin-polarized carriers from a ferromagnetic
+semiconductor into a nonmagnetic semiconductor, preferably one of those
+currently used for industrial applications such as Si - a workhorse of modern
+electronics. Ferromagnetic semiconductor EuO is long believed to be the best
+candidate for integration of magnetic semiconductor with Si. Although EuO
+proved to offer optimal conditions for effective spin injection into silicon
+and in spite of considerable efforts, the direct epitaxial stabilization of
+stoichiometric EuO thin films on Si without any buffer layer has not been
+demonstrated to date. Here we report a new technique for control of EuO/Si
+interface on submonolayer level which may have general implications for the
+growth of functional oxides on Si. Using this technique we solve a
+long-standing problem of direct epitaxial growth on silicon of thin EuO films
+which exhibit structural and magnetic properties of EuO bulk material. This
+result opens up new possibilities in developing all-semiconductor spintronic
+devices.",1407.5431v1
+2014-08-18,Unquenched $e_g^1$ orbital moment in the Mott insulating antiferromagnet KOsO4,"Applying the correlated electronic structure method based on density
+functional theory plus the Hubbard $U$ interaction, we have investigated the
+tetragonal scheelite structure Mott insulator KOsO$_4$, whose $e_g^1$
+configuration should be affected only slightly by spin-orbit couping (SOC). The
+method reproduces the observed antiferromagnetic Mott insulating state,
+populating the Os $d_{z^2}$ majority orbital. The quarter-filled $e_g$ manifold
+is characterized by a symmetry breaking due to the tetragonal structure, and
+the Os ion shows a crystal field splitting $\Delta_{cf}$ = 1.7 eV from the
+$t_{2g}$ complex, which is relatively small considering the high formal
+oxidation state Os$^{7+}$. The small magnetocrystalline anisotropy before
+including correlation (i.e., in the metallic state) is increased by more than
+an order of magnitude in the Mott-insulating state, a result of a strong
+interplay between large SOC and a strong correlation. In contrast to
+conventional wisdom that the $e_g$ complex will not support orbital magnetism,
+we find that for the easy axis [100] direction the substantial Os orbital
+moment $M_L\approx-0.2 \mu_B$ compensates half of the Os spin moment $M_S$ =
+0.4$\mu_B$. The origin of the orbital moment is analyzed and understood in
+terms of additional spin-orbital lowering of symmetry, and beyond that due to
+structural distortion, for magnetization along [100]. Further interpretation is
+assisted by analysis of the spin density and the Wannier function with SOC
+included.",1408.4078v2
+2015-06-12,Mechanisms and origins of half-metallic ferromagnetism in CrO2,"Chromium dioxide (CrO2) offers a rare example of metallic ferromagnetism
+among stoichiometric transition-metal oxides. What makes it even more
+remarkable is the half-metallic electronic structure. Today, CrO2 is widely
+used in magnetorecording and regarded as a promising spintronic material.
+Nevertheless, the key question ""Why is it ferromagnetic?"" remains largely
+unanswered, despite general interest to the problem and practical importance of
+CrO2. In the present work we challenge this question by combining
+first-principles electronic structure calculations with the model Hamiltonian
+approach and modern many-body methods for treating electron correlations. Our
+analysis demonstrates that the problem is indeed highly nontrivial: at the
+first glance, the ferromagnetism in CrO2 can be easily explained by Hund's rule
+related exchange processes in the narrow t2g band. However, the electron
+correlations, rigorously treated in the frameworks of dynamical mean-field
+theory, tend to destabilize this state. The ferromagnetism reemerges if,
+besides conventional kinetic energy changes in the t2g band, to consider other
+mechanism, involving direct exchange and magnetic polarization of the oxygen
+band. We show how all these contributions can be evaluated using
+first-principles electronic structure calculations. Our results explain the
+overall stability of the ferromagnetic state and provide the firm microscopic
+basis for understanding the magnetism of CrO2.",1506.03886v1
+2015-07-17,Phonons in ultrathin oxide films - 2D to 3D transition in FeO on Pt(111),"The structural and magnetic properties of ultrathin FeO(111) films on Pt(111)
+with thicknesses from 1 to 16 monolayers (ML) were studied using the nuclear
+inelastic scattering (NIS) of synchrotron radiation. Distinct evolution of
+vibrational characteristics with thickness that is revealed in the phonon
+density of states (PDOS) witnesses a textbook transition from 2D to 3D lattice
+dynamics. For the thinnest films of 1 and 2 ML, the low energy part of the PDOS
+followed a linear dependence in energy that is characteristic for 2-dimensional
+systems. This dependence gradually transforms with thickness to the bulk
+~E-square relation. Density functional theory phonon calculations perfectly
+reproduced the measured 1 ML PDOS within a simple model of a pseudomorphic
+FeO/Pt(111) interface. The calculations show that the 2D PDOS character is due
+to a weak coupling of the FeO film to the Pt(111) substrate. The evolution of
+the vibrational properties with an increasing thickness is closely related to a
+transient long range magnetic order and stabilization of an unusual structural
+phase.",1507.04874v6
+2015-08-29,First-principles studies of multiferroic and magnetoelectric materials,"Multiferroics are materials where two or more ferroic orders coexist owing to
+the interplay between spin, charge, lattice and orbital degrees of freedom. The
+explosive expansion of multiferroics literature in recent years demon-strates
+the fast growing interest in this field. In these studies, the first-principles
+calculation has played a pioneer role in the experiment explanation, mechanism
+discovery and prediction of novel multiferroics or magnetoelectric materials.
+In this review, we discuss, by no means comprehensively, the extensive
+applications and successful achievements of first-principles approach in the
+study of multiferroicity, magnetoelectric effect and tunnel junc-tions. In
+particular, we introduce some our recently developed methods, e.g., the orbital
+selective external potential (OSEP) method, which prove to be powerful tools in
+the finding of mechanisms responsible for the intriguing phe-nomena occurred in
+multiferroics or magnetoelectric materials. We also summarize first-principles
+studies on three types of electric control of magnetism, which is the common
+goal of both spintronics and multiferroics. Our review offers in depth
+understanding on the origin of ferroelectricity in transition metal oxides, and
+the coexistence of fer-roelectricity and ordered magnetism, and might be
+helpful to explore novel multiferroic or magnetoelectric materi-als in the
+future.",1508.07414v1
+2015-11-10,Topological magnetic phase in LaMnO$_3$ (111) bilayer,"Candidates for correlated topological insulators, originated from the
+spin-orbit coupling as well as Hubbard type correlation, are expected in the
+($111$) bilayer of perovskite-structural transition-metal oxides. Based on the
+first-principles calculation and tight-binding model, the electronic structure
+of a LaMnO$_3$ ($111$) bilayer sandwiched in LaScO$_3$ barriers has been
+investigated. For the ideal undistorted perovskite structure, the Fermi energy
+of LaMnO$_3$ ($111$) bilayer just stays at the Dirac point, rendering a
+semi-metal (graphene-like) which is also a half-metal (different from graphene
+nor previous studied LaNiO$_3$ ($111$) bilayer). The Dirac cone can be opened
+by the spin-orbit coupling, giving rise to nontrivial topological bands
+corresponding to the (quantized) anomalous Hall effect. For the realistic
+orthorhombic distorted lattice, the Dirac point moves with increasing Hubbard
+repulsion (or equivalent Jahn-Teller distortion). Finally, a Mott gap opens,
+establishing a phase boundary between the Mott insulator and topological
+magnetic insulator. Our calculation finds that the gap opened by spin-orbit
+coupling is much smaller in the orthorhombic distorted lattice ($\sim$$1.7$
+meV) than the undistorted one ($\sim$$11$ meV). Therefore, to suppress the
+lattice distortion can be helpful to enhance the robustness of topological
+phase in perovskite ($111$) bilayers.",1511.02968v1
+2016-01-20,Orbital Order and Spin Nematicity in the Tetragonal Phase of Electron-doped Iron-Pnictides NaFe$_{1-x}$Co$_{x}$As,"In copper-oxide and iron-based high temperature (high-$T_{\rm c}$)
+superconductors, many physical properties exhibit in-plane anisotropy, which is
+believed to be caused by a rotational symmetry-breaking nematic order, whose
+origin and its relationship to superconductivity remain elusive. In many
+iron-pnictides, a tetragonal-to-orthorhombic structural transition temperature
+$T_{\rm s}$ coincides with the magnetic transition temperature $T_{\rm N}$,
+making the orbital and spin degrees of freedom highly entangled. NaFeAs is a
+system where $T_{\rm s}$ = 54 K is well separated from $T_{\rm N}$ = 42 K,
+which helps simplify the experimental situation. Here we report nuclear
+magnetic resonance (NMR) measurements on NaFe$_{1-x}$Co$_x$As (0 $\leq x \leq$
+0.042) that revealed orbital and spin nematicity occurring at a temperature
+$T^{\rm *}$ far above $T_{\rm s}$ in the tetragonal phase. We show that the NMR
+spectra splitting and its evolution can be explained by an incommensurate
+orbital order that sets in below $T^{\rm *}$ and becomes commensurate below
+$T_{\rm s}$, which brings about the observed spin nematicity.",1601.05293v1
+2016-02-10,Oxygen vacancy induced room temperature metal-insulator transition in nickelates films and its potential application in photovoltaics,"Oxygen vacancy is intrinsically coupled with magnetic, electronic and
+transport properties of transition-metal oxide materials and directly
+determines their multifunctionality. Here, we demonstrate reversible control of
+oxygen content by post-annealing at temperature lower than 300 degree
+centigrade and realize the reversible metal-insulator transition in epitaxial
+NdNiO3 films. Importantly, over six orders of magnitude in the resistance
+modulation and a large change in optical band gap are demonstrated at room
+temperature without destroying the parent framework and changing the p-type
+conductive mechanism. Further study revealed that oxygen vacancies stabilized
+the insulating phase at room temperature is universal for perovskite nickelates
+films. Acting as electron donors, oxygen vacancies not only stabilize the
+insulating phase at room temperature, but also induce a large magnetization of
+~50 emu/cm3 due to the formation of strongly correlated Ni2+ t2g6eg2 states.
+The band gap opening is an order of magnitude larger than that of the thermally
+driven metal-insulator transition and continuously tunable. Potential
+application of the newly found insulating phase in photovoltaics has been
+demonstrated in the nickelates-based heterojunctions. Our discovery opens up
+new possibilities for strongly correlated perovskite nickelates.",1602.03310v1
+2016-07-05,Probing the core and shell contributions to exchange bias in Co/Co$_3$O$_4$ nanoparticles of controlled size,"Coupling at the interface of core/shell magnetic nanoparticles is known to be
+responsible for the exchange bias (EB) and the relative sizes of core and shell
+components are supposed to influence the associated phenomenology. In this
+work, we have prepared core/shell structured nanoparticles with the total
+averaged diameter around $\sim$ 27 nm and a wide range of shell thicknesses
+through the controlled oxidation of Co nanoparticles well dispersed in an
+amorphous silica host. Structural characterizations give compelling evidence of
+the formation of Co$_3$O$_4$ crystallite phase at the shells surrounding the Co
+core. Field cooled hysteresis loops display nonmonotonous dependence of the
+exchange bias $H_E$ and coercive $H_C$ fields, that become maximum for a sample
+with an intermediate shell thickness, at which lattice strain is also maximum
+for both the phases. Results of our atomistic Monte Carlo simulations of the
+particles with the same size and compositions as in experiments are in
+agreement with the experimental observations and have allowed us to identify a
+change in the contribution of the interfacial surface spins to the
+magnetization reversal giving rise to the maximum in $H_E$ and $H_C$.",1607.01336v1
+2016-09-22,Quantum meets classical phase transition: Low-temperature anomaly in disordered superconductors near $B_{c2}$,"Strongly disordered superconductors in a magnetic field display many
+characteristic properties of type-II superconductivity--- except at low
+temperatures where an anomalous linear $T$-dependence of the resistive critical
+field $B_{c2}$ is routinely observed. This behavior violates the conventional
+theory of superconductivity, and its origin remains a long-standing puzzle.
+Here we report on systematic measurements of the critical magnetic field and
+current on amorphous indium oxide films of various levels of disorder.
+Surprisingly, our measurements show that the $B_{c2}$ anomaly near
+zero-temperature is accompanied by a clear mean-field like scaling behavior of
+the critical current. We demonstrate theoretically that these are consequences
+of the vortex-glass ground state and its thermal fluctuations. This theory
+further predicts the linear-$T$ anomaly to occur in films as well as bulk
+superconductors with a slope that depends on the normal-state sheet
+resistance---in agreement with experimental data. Thus, our combined
+experimental and theoretical study reveals universal low-temperature behavior
+of $B_{c2}$ in a large class of disordered superconductors.",1609.07105v4
+2017-03-08,Fully gapped superconductivity with no sign change in the prototypical heavy-fermion CeCu2Si2,"In exotic superconductors including high-$T_c$ copper-oxides, the
+interactions mediating electron Cooper-pairing are widely considered to have a
+magnetic rather than the conventional electron-phonon origin. Interest in such
+exotic pairing was initiated by the 1979 discovery of heavy-fermion
+superconductivity in CeCu$_2$Si$_2$, which exhibits strong antiferromagnetic
+fluctuations. A hallmark of unconventional pairing by anisotropic repulsive
+interactions is that the superconducting energy gap changes sign as a function
+of the electron momentum, often leading to nodes where the gap goes to zero.
+Here, we report low-temperature specific heat, thermal conductivity and
+magnetic penetration depth measurements in CeCu$_2$Si$_2$, demonstrating the
+absence of gap nodes at any point on the Fermi surface. Moreover,
+electron-irradiation experiments reveal that the superconductivity survives
+even when the electron mean free path becomes substantially shorter than the
+superconducting coherence length. This indicates that superconductivity is
+robust against impurities, implying that there is no sign change in the gap
+function. These results show that, contrary to long-standing belief, heavy
+electrons with extremely strong Coulomb repulsions can condense into a
+fully-gapped s-wave superconducting state, which has an on-site attractive
+pairing interaction.",1703.02800v1
+2017-03-22,Hard superconducting gap and vortex-state spectroscopy in NbSe$_2$ van der Waals tunnel junctions,"Device-based tunnel spectroscopy of superconductors was first performed by
+Giaever, whose seminal work provided clear evidence for the spectral gap in the
+density of states (DOS) predicted by the Bardeen-Cooper-Schrieffer (BCS)
+theory. Since then, tunnel-barrier-based heterostructure devices have revealed
+myriad physical phenomena and found a range of applications. Most of these
+devices rely on a limited number of oxides, which form high-quality insulating,
+non-magnetic barriers. These barriers, however, do not grow well on all
+surfaces. Promising alternatives are van der Waals (vdW) materials, ultrathin
+layers of which can be precisely positioned on many surfaces; they have been
+shown to form tunnel barriers when engaged with graphene. Here we demonstrate
+that vdW semiconductors MoS$_2$ and WSe$_2$ deposited on the superconductor
+NbSe$_2$ form high quality tunnel barriers, with transparencies in the
+$10^{-8}$ range. Our measurements of the NbSe$_2$ DOS at 70mK show a hard
+superconducting gap, and a quasiparticle peak structure with clear evidence of
+contributions from two bands, with intrinsic superconductivity in both bands.
+In both perpendicular and parallel magnetic fields, we observe a sub-gap DOS
+associated with vortex bound states. The linear dependence of the zero-bias
+signal on perpendicular field allows us to confirm the s-wave nature of
+superconductivity in NbSe$_2$. As vdW tunnel barriers can be deployed on many
+solid surfaces, they extend the range of superconducting and other materials
+addressable not only by high resolution tunneling spectroscopy but also
+non-equilibrium and/or non-local transport.",1703.07677v1
+2017-08-28,Manipulating Multiple Order Parameters via Oxygen Vacancies: The case of Eu0.5Ba0.5TiO3-δ,"Controlling functionalities, such as magnetism or ferroelectricity, by means
+of oxygen vacancies (VO) is a key issue for the future development of
+transition metal oxides. Progress in this field is currently addressed through
+VO variations and their impact on mainly one order parameter. Here we reveal a
+new mechanism for tuning both magnetism and ferroelectricity simultaneously by
+using VO. Combined experimental and density-functional theory studies of
+Eu0.5Ba0.5TiO3-{\delta}, we demonstrate that oxygen vacancies create Ti3+ 3d1
+defect states, mediating the ferromagnetic coupling between the localized Eu
+4f7 spins, and increase an off-center displacement of Ti ions, enhancing the
+ferroelectric Curie temperature. The dual function of Ti sites also promises a
+magnetoelectric coupling in the Eu0.5Ba0.5TiO3-{\delta}.",1708.08235v1
+2010-05-24,Magnetic and Electronic Properties of Li$_x$CoO$_2$ Single Crystals,"Measurements of electrical resistivity ($\rho$), DC magnetization ($M$) and
+specific heat ($C$) have been performed on layered oxide Li$_x$CoO$_2$
+(0.25$\leq$$x$$\leq$0.99) using single crystal specimens. The $\rho$ versus
+temperature ($T$) curve for $x$=0.90 and 0.99 is found to be insulating but a
+metallic behavior is observed for 0.25$\leq$$x$$\leq$0.71. At $T_{\rm
+S}$$\sim$155 K, a sharp anomaly is observed in the $\rho$$-$$T$, $M$$-$$T$ and
+$C$$/$$T$$-$$T$ curves for $x$=0.66 with thermal hysteresis, indicating the
+first-order charactor of the transition. The transition at $T_{\rm S}$$\sim$155
+K is observed for the wide range of $x$=0.46$-$0.71. It is found that the
+$M$$-$$T$ curve measured after rapid cool becomes different from that after
+slow cool below $T_{\rm F}$, which is $\sim$130 K for $x$=0.46$-$0.71. $T_{\rm
+F}$ is found to agree with the temperature at which the motional narrowing in
+the $^7$Li NMR line width is observed, indicating that the Li ions stop
+diffusing and order at the regular site below $T_{\rm F}$. The ordering of Li
+ions below $T_{\rm F}$$\sim$130 K is likely to be triggered and stabilized by
+the charge ordering in CoO$_2$ layers below $T_{\rm S}$.",1005.4253v3
+2014-03-26,Unconventional pairing and electronic dimerization instabilities in the doped Kitaev-Heisenberg model,"We study the quantum many-body instabilities of the $t -J_{\mathrm{K}} -
+J_{\mathrm{H}}$ Kitaev-Heisenberg Hamiltonian on the honeycomb lattice as a
+minimal model for a doped spin-orbit Mott insulator. This spin-$1/2$ model is
+believed to describe the magnetic properties of the layered transition-metal
+oxide Na$_2$IrO$_3$. We determine the ground-state of the system with finite
+charge-carrier density from the functional renormalization group (fRG) for
+correlated fermionic systems. To this end, we derive fRG flow-equations adapted
+to the lack of full spin-rotational invariance in the fermionic interactions,
+here represented by the highly frustrated and anisotropic Kitaev exchange term.
+Additionally employing a set of Ward identities for the Kitaev-Heisenberg
+model, the numerical solution of the flow equations suggests a rich phase
+diagram emerging upon doping charge carriers into the ground-state manifold
+($\mathbb{Z}_2$ quantum spin liquids and magnetically ordered phases). We
+corroborate superconducting triplet $p$-wave instabilities driven by
+ferromagnetic exchange and various singlet pairing phases. For filling $\delta
+> 1/4$, the $p$-wave pairing gives rise to a topological state with protected
+Majorana edge-modes. For antiferromagnetic Kitaev and ferromagnetic Heisenberg
+exchange we obtain bond-order instabilities at van Hove filling supported by
+nesting and density-of-states enhancement, yielding dimerization patterns of
+the electronic degrees of freedom on the honeycomb lattice. Further, our flow
+equations are applicable to a wider class of model Hamiltonians.",1403.6762v2
+2017-04-20,Orbital and spin ordering physics of the Mn$_3$O$_4$ spinel,"Motivated by recent experiments, we present a comprehensive theoretical study
+of the geometrically frustrated strongly correlated magnetic insulator
+Mn$_3$O$_4$ spinel oxide based on a microscopic Hamiltonian involving lattice,
+spin and orbital degrees of freedom. Possessing the physics of degenerate e$_g$
+orbitals, this system shows a strong Jahn-Teller effect at high temperatures.
+Further, careful attention is paid to the special nature of the superexchange
+physics arising from the 90$^o$ Mn-O-Mn bonding angle. The Jahn-Teller and
+superexchange-based orbital-spin Hamiltonians are then analysed in order to
+track the dynamics of orbital and spin ordering. We find that a
+high-temperature structural transition results in orbital ordering whose nature
+is mixed with respect to the two originally degenerate $e_{g}$ orbitals. This
+ordering of orbitals is shown to relieve the intrinsic geometric frustration of
+the spins on the spinel lattice, leading to ferrimagnetic Yafet-Kittel ordering
+at low-temperatures. Finally, we develop a model for a magnetoelastic coupling
+in Mn$_3$O$_4$, enabling a systematic understanding of the experimentally
+observed complexity in the low-temperature structural and magnetic
+phenomenology of this spinel. Our analysis predicts that a quantum
+fluctuation-driven orbital-spin liquid phase may be stabilised at low
+temperatures upon the application of pressure.",1704.06026v1
+2018-05-18,Strain-Engineering Mott-Insulating La$_2$CuO$_4$,"The transition temperature $T_\textrm{c}$ of unconventional superconductivity
+is often tunable. For a monolayer of FeSe, for example, the sweet spot is
+uniquely bound to titanium-oxide substrates. By contrast for
+La$_{2-\mathrm{x}}$Sr$_\mathrm{x}$CuO$_4$ thin films, such substrates are
+sub-optimal and the highest $T_\textrm{c}$ is instead obtained using
+LaSrAlO$_4$. An outstanding challenge is thus to understand the optimal
+conditions for superconductivity in thin films: which microscopic parameters
+drive the change in $T_\mathrm{c}$ and how can we tune them? Here we
+demonstrate, by a combination of x-ray absorption and resonant inelastic x-ray
+scattering spectroscopy, how the Coulomb and magnetic-exchange interaction of
+La$_2$CuO$_4$ thin films can be enhanced by compressive strain. Our experiments
+and theoretical calculations establish that the substrate producing the largest
+$T_\textrm{c}$ under doping also generates the largest nearest neighbour
+hopping integral, Coulomb and magnetic-exchange interaction. We hence suggest
+optimising the parent Mott state as a strategy for enhancing the
+superconducting transition temperature in cuprates.",1805.07173v3
+2018-04-18,Heteroatomic jet fuel components: Lichen substances as fuel component and potential additives,"This article presents chemical analysis of jet fuel (Jet A-1) heteroatomic
+fuel components with identification of an antioxidant lichen substance in
+methanol extracted fuel samples. Thermal stressing of jet fuel produces soluble
+macromolecular oxidatively reactive species (SMORS) and heteroatomic deposits.
+SMORS are deposit precursors and elementary heteroatomic units containing
+unsaturated and aromatic hydrocarbons. Fuel additives such as antioxidants can
+inhibit SMORS and deposit formation within limited heating residence time and
+temperature range. Jet A-1 was thermally stressed in the autoxidation regime
+(150 to 300 0C) followed by spectroscopic analysis. Thermally stressed jet fuel
+static tests electrospray ionization mass spectra (ESI-MS) show higher
+molecular weight compounds in the mass range 300-1000 Da compared with
+unstressed fuel samples supporting deposition. Jet A-1 samples were analyzed by
+electrospray ion source mass spectrometry (ESI-MS), Fourier transform infrared
+(FTIR) and 13C nuclear magnetic resonance (NMR) spectroscopy. FTIR bands for
+oxygen containing species reveal the presence of alcohol, phenol and ether
+groups. 13C nuclear magnetic resonance (NMR) standard and distorsionless
+enhancement polarization transfer (DEPT 135) spectra recorded heteroatomic
+alkoxy species in both unstressed and thermally stressed fuel samples. Natural
+products polyphenols and lichen derived oxygenated compounds are excellent
+antioxidants. A new perspective of using lichen substances as fuel additives
+emerged in this study. Exploring further, natural products extraction methods
+optimization remains a key challenge and advantages of polyphenolic lichen
+acids as potential fuel and chemical additives are discussed.",1805.11675v1
+2008-07-03,Electric Field Control of the LaAlO$_{3}$/SrTiO$_{3}$ Interface Ground State,"Interfaces between complex oxides are emerging as one of the most interesting
+playgrounds in condensed matter physics. In this special setting, in which
+translational symmetry is artificially broken, a variety of novel electronic
+phases can be promoted. Theoretical studies predict complex phase diagrams and
+suggest the key role of the carrier density in determining the systems ground
+states. A particularly fascinating system is the interface between the
+insulators LaAlO$_{3}$ and SrTiO$_{3}$, which displays conductivity with high
+mobility. Recently two possible ground states have been experimentally
+identified: a magnetic state and a two dimensional (2D) superconducting
+condensate. In this Letter we use the electric field effect to explore the
+phase diagram of the system. The electrostatic tuning of the carrier density
+allows an on/off switching of superconductivity and drives a quantum phase
+transition (QPT) between a 2D superconducting state and an insulating state
+(2D-QSI). Analyses of the magnetotransport properties in the insulating state
+are consistent with weak localisation and do not provide evidence for
+magnetism. The electric field control of superconductivity demonstrated here
+opens the way to the development of novel mesoscopic superconducting circuits",0807.0585v1
+2008-07-08,Dispersing bimagnons and doping induced bimagnon-charge modes in superconducting cuprates,"In the early days of high temperature superconductivity it was already
+recognized that magnetic properties of these materials are intimately related
+to the superconducting ones . When doped, the long-range ordered
+antiferromagnetic background of pristine copper-oxide insulators melts away and
+makes room for a spin liquid and superconductivity. By resonant inelastic x-ray
+scattering (RIXS) in the soft regime we probe the hitherto inaccessible
+dynamical multiple-spin correlations of the magnetic background in a series of
+parent compounds and in high Tc materials [NCCO (Nd2-xCexCuO4) and LSCO
+(La2-xSrxCuO4)]. High resolution measurements allows the clear observation of
+dispersing bimagnon excitations. In the undoped compounds the theory, fits the
+data on these coherent spin excitations without free parameters. In nearly
+optimally doped LSCO we observe the appearance of a new collective excitation
+at an energy of 250 +/- 60 meV having the signature of a coupled
+bimagnon-charge mode. It has a strongly reduced dispersion and lies in a so far
+unexplored region of momentum and energy space in the mid-infrared.",0807.1140v1
+2013-09-23,Zinc Oxide - From Dilute Magnetic Doping to Spin Transport,"During the past years there has been renewed interest in the wide-bandgap
+II-VI semiconductor ZnO, triggered by promising prospects for spintronic
+applications. First, ferromagnetism was predicted for dilute magnetic doping.
+In comprehensive investigation of ZnO:Co thin films based on the combined
+measurement of macroscopic and microscopic properties, we find no evidence for
+carrier-mediated itinerant ferromagnetism. Phase-pure, crystallographically
+excellent ZnO:Co is uniformly paramagnetic. Superparamagnetism arises when
+phase separation or defect formation occurs, due to nanometer-sized metallic
+precipitates. Other compounds like ZnO:(Li,Ni) and ZnO:Cu do not exhibit
+indication of ferromagnetism.
+  Second, its small spin-orbit coupling and correspondingly large spin
+coherence length makes ZnO suitable for transporting or manipulating spins in
+spintronic devices. From optical pump/optical probe experiments, we find a spin
+dephasing time of the order of 15 ns at low temperatures which we attribute to
+electrons bound to Al donors. In all-electrical magnetotransport measurements,
+we successfully create and detect a spin-polarized ensemble of electrons and
+transport this spin information across several nanometers. We derive a spin
+lifetime of 2.6 ns for these itinerant spins at low temperatures, corresponding
+well to results from an electrical pump/optical probe experiment.",1309.5857v1
+2014-05-16,Mixed configuration ground state in Iron(II) Phthalocyanine,"We calculate the angular dependence of the x-ray linear and circular
+dichroism at the $L_{2,3}$ edges of $\alpha$-Fe(II) Phthalocyanine (FePc) thin
+films using a ligand field model with full configuration interaction. We find
+the best agreement with the experimental spectra for a mixed ground state of
+$^3E_{g}(a_{1g}^2e_g^3b_{2g}^1)$ and $^3B_{2g}(a_{1g}^1e_g^4b_{2g}^1)$ with the
+two configurations coupled by the spin-orbit interaction. The $^3E_{g}(b)$ and
+$^3B_{2g}$ states have an easy axis and plane anisotropies, respectively. Our
+model accounts for an easy-plane magnetic anisotropy and the measured
+magnitudes of the in-plane orbital and spin moments. The proximity in energy of
+the two configurations allows a switching of the magnetic anisotropy from easy
+plane to easy axis with a small change in the crystal field, as recently
+observed for FePc adsorbed on an oxidized Cu surface. We also discuss the
+possibility of a quintet ground state ($^5A_{1g}$ is 250~meV above the ground
+state) with planar anisotropy by manipulation of the Fe-C bond length by
+depositing the complex on a substrate that is subjected to a mechanical strain.",1405.4313v4
+2016-12-15,The properties of ultrapure delafossite metals,"Although they were first synthesized in chemistry laboratories nearly fifty
+years ago, the physical properties of the metals PdCoO2, PtCoO2 and PdCrO2 have
+only more recently been studied in detail. The delafossite structure contains
+triangular co-ordinated atomic layers, and electrical transport in the
+delafossite metals is strongly two-dimensional. Their most notable feature is
+their in-plane conductivity, which is amazingly high for oxide metals. At room
+temperature, the conductivity of non-magnetic PdCoO2 and PtCoO2 is higher per
+carrier than those of any alkali metal and even the most conductive elements,
+copper and silver. At low temperatures the best crystals have resistivities of
+a few n{\Omega}cm, corresponding to mean free paths of tens of microns. PdCrO2
+is a frustrated antiferromagnetic metal, with magnetic scattering contributing
+to the resistivity at high temperatures and small gaps opening in the Fermi
+surface below the N\'eel temperature. There is good evidence that electronic
+correlations are weak in the Pd/Pt layers but strong in the Co/Cr layers;
+indeed the Cr layer in PdCrO2 is thought to be a Mott insulator. The
+delafossite metals therefore act like natural heterostructures between strongly
+correlated and nearly free electron sub-systems. Combined with the extremely
+high conductivity, they provide many opportunities to study electrical
+transport and other physical properties in new regimes. The purpose of this
+review is to describe current knowledge of these fascinating materials and set
+the scene for what is likely to be a considerable amount of future research.",1612.04948v1
+2017-06-30,A review and prospects for Nb3Sn superconductor development,"Nb3Sn superconductors have significant applications in constructing
+high-field (> 10 T) magnets. This article briefly reviews development of Nb3Sn
+superconductor and proposes prospects for further improvement. It is shown that
+significant improvement of critical current density (Jc) is needed for future
+accelerator magnets. After a brief review of the development of Nb3Sn
+superconductors, the factors controlling Jc are summarized and correlated with
+their microstructure and chemistry. The non-matrix Jc of Nb3Sn conductors is
+mainly determined by three factors: the fraction of current-carrying Nb3Sn
+phase in the non-matrix area, the upper critical field Bc2, and the flux-line
+pinning capacity. Then prospects to improve the three factors are discussed
+respectively. An analytic model was developed to show how the ratios of
+precursors determine the phase fractions after heat treatment, based on which
+it is predicted that the limit of current-carrying Nb3Sn fraction in
+subelements is ~65%. Then, since Bc2 is largely determined by the Nb3Sn
+stoichiometry, a thermodynamic/kinetic theory was presented to show what
+essentially determines the Sn content of Nb3Sn conductors. This theory explains
+the influences of Sn sources and Ti addition on stoichiometry and growth rate
+of Nb3Sn layers. Next, to improve flux pinning, previous efforts in this
+community to introduce additional pinning centers (APC) to Nb3Sn wires are
+reviewed, and an internal oxidation technique is described. Finally, prospects
+for further improvement of non-matrix Jc of Nb3Sn conductors are discussed, and
+it is seen that the only opportunity for further significantly improving Jc
+lies in improving the flux pinning.",1706.10253v1
+2017-12-12,Engineering the eigenstates of coupled spin-1/2 atoms on a surface,"Quantum spin networks having engineered geometries and interactions are
+eagerly pursued for quantum simulation and access to emergent quantum phenomena
+such as spin liquids. Spin-1/2 centers are particularly desirable because they
+readily manifest coherent quantum fluctuations. Here we introduce a
+controllable spin-1/2 architecture consisting of titanium atoms on a magnesium
+oxide surface. We tailor the spin interactions by atomic-precision positioning
+using a scanning tunneling microscope (STM), and subsequently perform electron
+spin resonance (ESR) on individual atoms to drive transitions into and out of
+quantum eigenstates of the coupled-spin system. Interactions between the atoms
+are mapped over a range of distances extending from highly anisotropic dipole
+coupling, to strong exchange coupling. The local magnetic field of the magnetic
+STM tip serves to precisely tune the superposition states of a pair of spins.
+The precise control of the spin-spin interactions and ability to probe the
+states of the coupled-spin network by addressing individual spins will enable
+exploration of quantum many-body systems based on networks of spin-1/2 atoms on
+surfaces.",1712.04082v1
+2018-01-16,Spin-orbit-torque and magnetic damping in tailored ferromagnetic bilayers,"We study spin-orbit-torque-driven ferromagnetic resonance (FMR) in
+ferromagnetic (FM) bilayers, consisting of Co and permalloy (Py), sandwiched
+between Pt and MgO layers. We find that the FM layer in contact with the Pt
+layers dominantly determines that spin Hall angle, which is consistent with the
+spin-transparency model. By contrast, the FMR linewidths are considerably
+influenced not only by the spin-pumping effect across the Pt|FM in terface but
+also by the spin relaxation such as two-magnon scattering at the FMMgO
+interface.The CoMgO interface leads to notably increased FMR linewidths, while
+the Py|MgO interface has less effect. This different contribution of each
+interface to the spin Hall angel and dissipation parameter suggests that the
+stack configuration of Pt|Co|Py|MgO requires less writing energy than
+Pt|Py|Co|MgO in spin-orbit-torque-driven magnetic switching. Our approach
+offers a promising method to optimize material parameters by engineering either
+interfaces in contact with the heavy-metal or the oxide layer.",1801.05131v2
+2018-09-05,Tuning interactions in the spin-ice materials Dy$_2$Ge$_{2-x}$Si$_x$O$_7$ by silicon substitution,"We report that the lattice constant of Dy$_2$Ge$_{2-x}$Si$_x$O$_7$ ($x=0,
+0.02, 0.08, 0.125$) can be systematically reduced by substituting the
+non-magnetic germanium ion in the cubic pyrochlore oxide with silicon. A
+multi-anvil high-pressure synthesis was performed up to 16 GPa and 1100
+$^\circ$C to obtain polycrystalline samples in a solid-state reaction.
+Measurements of magnetization, ac susceptibility, and heat capacity reveal the
+typical signatures of a spin-ice phase. From the temperature shift of the
+peaks, observed in the temperature-dependent heat capacity, we deduce an
+increase of the strength of the exchange interaction. In conclusion, the
+reduced lattice constant leads to a changed ratio of the competing exchange and
+dipolar interaction. This puts the new spin-ice compounds closer towards the
+phase boundary of short-range spin-ice arrangement and antiferromagnetic
+long-range order consistent with an observed reduction of the monopole energy
+scale.",1809.01480v2
+2019-06-06,Novel Mechanocaloric Materials for Solid-State Cooling Applications,"Solid-state cooling is an environmentally friendly and highly scalable
+technology that may solve most of the problems associated with current
+refrigerant methods. Solid-state cooling consists of applying external fields
+on caloric materials, which react thermally as a result of induced phase
+transformations. From an energy efficiency point of view, mechanocaloric
+compounds, in which the phase transitions of interest are driven by mechanical
+stresses, probably represent the most encouraging type of caloric materials.
+Conventional mechanocaloric materials like shape-memory alloys already display
+good cooling performances however in most cases they also present critical
+mechanical fatigue and hysteresis problems that limit their applicability.
+Finding new mechanocaloric materials and mechanisms able to overcome those
+problems while simultaneously rendering large temperature shifts, is necessary
+to further advance the field of solid-state cooling. In this article, we review
+novel families of mechanocaloric materials that in recent years have been shown
+to be specially promising in the aspects that conventional mechanocaloric
+materials are not, and which exhibit unconventional but significant caloric
+effects. We put an emphasis on elastocaloric materials, in which the targeted
+cooling spans are obtained through uniaxial stresses, since from an applied
+perspective these appear to be the most accomplished. Two different types of
+mechanocaloric materials emerge as particularly hopeful from our analysis,
+compounds that exhibit field-induced order disorder phase transitions involving
+either ions or molecules (fast-ion conductors and plastic crystals), and
+multiferroics in which the structural parameters are strongly coupled with
+polar and/or magnetic degrees of freedom (magnetic alloys and oxide
+perovskites).",1906.02363v1
+2019-06-10,Néel and stripe ordering from spin-orbital entanglement in $α$-Sr$_2$CrO$_4$,"The rich phenomenology engendered by the coupling between the spin and
+orbital degrees of freedom has become appreciated as a key feature of many
+strongly-correlated electron systems. The resulting emergent physics is
+particularly prominent in a number of materials, from Fe-based unconventional
+superconductors to transition metal oxides, including manganites and vanadates.
+Here, we investigate the electronic ground states of $\alpha$-Sr$_2$CrO$_4$, a
+compound that is a rare embodiment of the spin-1 Kugel-Khomskii model on the
+square lattice -- a paradigmatic platform to capture the physics of coupled
+magnetic and orbital electronic orders. We have used resonant X-ray diffraction
+at the Cr-$K$ edge to reveal N\'{e}el magnetic order at the in-plane wavevector
+$\mathbf{Q}_N = (1/2, 1/2)$ below $T_N = 112$ K, as well as an additional
+electronic order at the 'stripe' wavevector $\mathbf{Q}_s = (1/2, 0)$ below
+T$_s$ $ \sim 50$ K. These findings are examined within the framework of the
+Kugel-Khomskii model by a combination of mean-field and Monte-Carlo approaches,
+which supports the stability of the spin N\'{e}el phase with subsequent
+lower-temperature stripe orbital ordering, revealing a candidate mechanism for
+the experimentally observed peak at $\mathbf{Q}_s$. On the basis of these
+findings, we propose that $\alpha$-Sr$_2$CrO$_4$ serves as a new platform in
+which to investigate multi-orbital physics and its role in the low-temperature
+phases of Mott insulators.",1906.04194v2
+2020-04-15,Interfacial-hybridization-modified Ir Ferromagnetism and Electronic Structure in LaMnO$_3$/SrIrO$_3$ Superlattices,"Artificially fabricated 3$d$/5$d$ superlattices (SLs) involve both strong
+electron correlation and spin-orbit coupling in one material by means of
+interfacial 3$d$-5$d$ coupling, whose mechanism remains mostly unexplored. In
+this work we investigated the mechanism of interfacial coupling in
+LaMnO$_3$/SrIrO$_3$ SLs by several spectroscopic approaches. Hard x-ray
+absorption, magnetic circular dichroism and photoemission spectra evidence the
+systematic change of the Ir ferromagnetism and the electronic structure with
+the change of the SL repetition period. First-principles calculations further
+reveal the mechanism of the SL-period dependence of the interfacial electronic
+structure and the local properties of the Ir moments, confirming that the
+formation of Ir-Mn molecular orbital is responsible for the interfacial
+coupling effects. The SL-period dependence of the ratio between spin and
+orbital components of the Ir magnetic moments can be attributed to the
+realignment of electron spin during the formation of the interfacial molecular
+orbital. Our results clarify the nature of interfacial coupling in this
+prototypical 3$d$/5$d$ SL system and the conclusion will shed light on the
+study of other strongly correlated and spin-orbit coupled oxide
+hetero-interfaces.",2004.06864v1
+2020-12-25,Superconductivity to 262 kelvin via catalyzed hydrogenation of yttrium at high pressures,"Room temperature superconductivity has been achieved under high pressure in
+an organically derived carbonaceous sulfur hydride with a critical
+superconducting transition temperature (Tc) of 288 kelvin. This development is
+part of a new class of dense, hydrogen rich materials with remarkably high
+critical temperatures. Metal superhydrides are a subclass of these materials
+that provide a different and potentially more promising route to very high Tc
+superconductivity. The most promising binary metal superhydrides contain
+alkaline or rare earth elements, and recent experimental observations of LaH10
+have shown them capable of Tc s up to 250 to 260 kelvin. Predictions have shown
+yttrium superhydrides to be the most promising with an estimated Tc in excess
+of 300 kelvin for YH10. Here we report the synthesis of an yttrium superhydride
+that exhibits superconductivity at a critical temperature of 262 kelvin at 182
+gigapascal. A palladium thin film assists the synthesis by protecting the
+sputtered yttrium from oxidation and promoting subsequent hydrogenation. Phonon
+mediated superconductivity is established by the observation of zero
+resistance, an isotope effect and the reduction of Tc under an external
+magnetic field. The upper critical magnetic field is 103 tesla at zero
+temperature. We suggest YH9 is the synthesized product based on comparison of
+the measured Raman spectra and Tc to calculated Raman results.",2012.13627v1
+2021-01-06,Experimental System for Molecular Communication in Pipe Flow With Magnetic Nanoparticles,"In the emerging field of molecular communication (MC), testbeds are needed to
+validate theoretical concepts, motivate applications, and guide further
+modeling efforts. To this end, this paper presents a flexible and extendable
+in-vessel testbed for flow-based macroscopic MC, abstractly modeling, e.g., a
+part of a chemical reactor or a blood vessel. Signaling is based on injecting
+non-reactive superparamagnetic iron oxide nanoparticles (SPIONs) dispersed in
+an aqueous suspension into a tube with background flow. A commercial magnetic
+susceptometer is used for non-intrusive downstream signal reception. To shed
+light on the operation of the testbed, we identify the physical mechanisms
+governing the transmission, propagation, and reception of the
+information-carrying SPIONs. Moreover, to facilitate system design, we propose
+a closed-form parametric expression for the end-to-end channel impulse response
+(CIR). The proposed CIR model is shown to consistently capture the
+experimentally observed distance-dependent impulse response peak heights and
+peak decays for transmission distances from 5cm to 40cm. Moreover, to validate
+our testbed, reliable communication is demonstrated based on experimental data
+for model-agnostic and model-based detection methods.",2101.02201v2
+2021-01-19,"Quantitative analysis of iron sand mineral content from the south coast of Cidaun, West Java using rietveld refinement method","Iron sand is one of the abundant natural resources in Indonesia, especially
+on the south coast of Cidaun; West Java which is the basic material for
+building and metal industry. Iron mineral content is generally metal oxide such
+as magnetite, hematite and silica/quartz. Sand with iron content used in this
+study is derived from beach sand Desa Kertajadi, Kecamatan Cidaun, Kabupaten
+Cianjur, Jawa Barat. Then mass of 2 kg sand was separated using a magnetic
+separator in order to obtain magnetic and nonmagnetic mineral content. After
+nine rounds of separation takes two different types of samples that are no
+separation sand (TS) sample and concentrate in the third separation (S3)
+sample. The sample is then examined by X-Ray Diffraction (XRD) measurement and
+analyzed quantitatively using MAUD software to determine the content of Fe3O4
+(magnetite) by using the Rietveld refinement method from XRD data. As the
+analysis result, the magnetite content contained in iron sand is counted
+quantitatively for each different sample. For iron sand samples (TS) yielding a
+24.27 percent of magnetite and a third concentrate separation sample (S3)
+yields 61.98 percent.",2101.10442v1
+2017-05-05,Nanostructured complex oxides as a route towards thermal behavior in artificial spin ice systems,"We have used soft x-ray photoemission electron microscopy to image the
+magnetization of single domain La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ nano-islands
+arranged in geometrically frustrated configurations such as square ice and
+kagome ice geometries. Upon thermal randomization, ensembles of nano-islands
+with strong inter-island magnetic coupling relax towards low-energy
+configurations. Statistical analysis shows that the likelihood of ensembles
+falling into low-energy configurations depends strongly on the annealing
+temperature. Annealing to just below the Curie temperature of the ferromagnetic
+film (T$_{C}$ = 338 K) allows for a much greater probability of achieving low
+energy configurations as compared to annealing above the Curie temperature. At
+this thermally active temperature of 325 K, the ensemble of ferromagnetic
+nano-islands explore their energy landscape over time and eventually transition
+to lower energy states as compared to the frozen-in configurations obtained
+upon cooling from above the Curie temperature. Thus, this materials system
+allows for a facile method to systematically study thermal evolution of
+artificial spin ice arrays of nano-islands at temperatures modestly above room
+temperature.",1705.02309v1
+2017-11-08,Surface impedance and optimum surface resistance of a superconductor with imperfect surface,"We calculate a low-frequency surface impedance of a dirty, s-wave
+superconductor with an imperfect surface incorporating either a thin layer with
+a reduced pairing constant or a thin, proximity-coupled normal layer. Such
+structures model realistic surfaces of superconducting materials which can
+contain oxide layers, absorbed impurities or nonstoichiometric composition. We
+solved the Usadel equations self-consistently and obtained spatial
+distributions of the order parameter and the quasiparticle density of states
+which then were used to calculate a low-frequency surface resistance $R_s(T)$
+and the magnetic penetration depth $\lambda(T)$ as functions of temperature in
+the limit of local London electrodynamics. It is shown that the imperfect
+surface in a single-band s-wave superconductor results in a non-exponential
+temperature dependence of $Z(T)$ at $T\ll T_c$ which can mimic the behavior of
+multiband or d-wave superconductors. The imperfect surface and the broadening
+of the gap peaks in the quasiparticle density of states $N(\epsilon)$ in the
+bulk give rise to a weakly temperature-dependent residual surface resistance.
+We show that the surface resistance can be optimized and even reduced below its
+value for an ideal surface by engineering $N(\epsilon)$ at the surface using
+pairbreaking mechanisms, particularly, by incorporating a small density of
+magnetic impurities or by tuning the thickness and conductivity of the normal
+layer and its contact resistance. The results of this work address the limit of
+$R_s$ in superconductors at $T\ll T_c$, and the ways of engineering the optimal
+density of states by surface nano-structuring and impurities to reduce losses
+in superconducting micro-resonators, thin film strip lines, and radio frequency
+cavities for particle accelerators.",1711.03077v1
+2017-11-27,Spectroscopy of bulk and few-layer superconducting NbSe$_2$ with van der Waals tunnel junctions,"Tunnel junctions, a well-established platform for high-resolution
+spectroscopy of superconductors, require defect-free insulating barriers with
+clean engagement to metals on both sides. Extending the range of materials
+accessible to tunnel junction fabrication, beyond the limited selection which
+allows high-quality oxide formation, requires the development of alternative
+fabrication techniques. Here we show that van-der-Waals (vdW) tunnel barriers,
+fabricated by stacking layered semiconductors on top of the transition metal
+dichalcogenide (TMD) superconductor NbSe$_2$, sustain a stable, low noise
+tunneling current, and exhibit strong suppression of sub-gap tunneling. We
+utilize the technique to measure the spectra of bulk (20 nm) and ultrathin (3-
+and 4-layer) devices at 70 mK. The spectra exhibit two distinct energy gaps,
+the larger of which decreases monotonously with thickness and $T_C$, in
+agreement with BCS theory. The spectra are analyzed using a two-band model
+modified to account for depairing. We show that in the bulk, the smaller gap
+exhibits strong depairing in an in-plane magnetic field, consistent with a high
+Fermi velocity. In the few-layer devices, depairing of the large gap is
+negligible, consistent with out-of-plane spin-locking due to Ising spin-orbit
+coupling. Our results demonstrate the utility of vdW tunnel junctions in
+mapping the intricate spectral evolution of TMD superconductors over a range of
+magnetic fields.",1711.09615v2
+2018-12-07,"Ab-initio approach to the stability and the structural, electronic and magnetic properties of the (001) Znfe2O4 surface terminations","We present a Density Functional Theory (DFT) based study of the structural
+and magnetic properties of the (001) surface of the semiconducting oxide
+ZnFe2O4 (spinel structure). The calculations were performed using the DFT based
+ab initio plane wave and pseudopotential method as implemented in the Quantum
+Espresso code. The all electron Full-potential linearized-augmented-plane-wave
+method (FP-LAPW) was also employed to check the accuracy of plane wave method.
+In both calculations the DFT+U methodology was employed and different (001)
+surface terminations of ZnFe2O4 were studied: We find that the surface
+terminated in Zn is the stable one. For all the (001) surface terminations our
+calculations predict that the Zn-Fe cationic inversion (antisites), which are
+defects in bulk ZnFe2O4, becomes stable and an integral part of the surface.
+Also, a ferrimagnetic behavior is predicted for the case of antisites in the
+superficial layer. Our results for different properties of the surface of
+ZnFe2O4 are compared with those obtained in bulk samples and those reported in
+the literature.",1812.03129v2
+2019-04-29,Metal to Orthogonal Metal Transition,"Orthogonal metal is a new quantum metallic state that conducts electricity
+but acquires no Fermi surface (FS) or quasiparticles, and hence orthogonal to
+the established paradigm of Landau's Fermi-liquid (FL). Such a state may hold
+the key of understanding the perplexing experimental observations of quantum
+metals that are beyond FL, i.e., dubbed non-Fermi-liquid (nFL), ranging from
+the Cu- and Fe-based oxides, heavy fermion compounds to the recently discovered
+twisted graphene heterostructures. However, to fully understand such an exotic
+state of matter, at least theoretically, one would like to construct a lattice
+model and to solve it with unbiased quantum many-body machinery. Here we
+achieve this goal by designing a 2D lattice model comprised of fermionic and
+bosonic matter fields coupled with dynamic $\mathbb Z_2$ gauge fields, and
+obtain its exact properties with sign-free quantum Monte Carlo simulations. We
+find that as the bosonic matter fields become disordered, with the help of
+deconfinement of the $\mathbb Z_2$ gauge fields, the system reacts with
+changing its nature from the conventional normal metal with an FS to an
+orthogonal metal of nFL without FS and quasiparticles and yet still responds to
+magnetic probe like an FL. Such a quantum phase transition from a normal metal
+to an orthogonal metal, with its electronic and magnetic spectral properties
+revealed, is calling for the establishment of new paradigm of quantum metals
+and their transition with conventional ones.",1904.12872v2
+2019-11-07,Metal-Insulator and Magnetic Phase Diagram of Ca$_2$RuO$_4$ from Auxiliary Field Quantum Monte Carlo and Dynamical Mean Field Theory,"Layered perovskite ruthenium oxides exhibit a striking series of
+metal-insulator and magnetic-nonmagnetic phase transitions easily tuned by
+temperature, pressure, epitaxy, and nonlinear drive. In this work, we combine
+results from two complementary state of the art many-body methods, Auxiliary
+Field Quantum Monte Carlo and Dynamical Mean Field Theory, to determine the
+low-temperature phase diagram of Ca$_2$RuO$_4$. Both methods predict a low
+temperature, pressure-driven metal-insulator transition accompanied by a
+ferromagnetic-antiferromagnetic transition. The properties of the ferromagnetic
+state vary non-monotonically with pressure and are dominated by the ruthenium
+$d_{xy}$ orbital, while the properties of the antiferromagnetic state are
+dominated by the $d_{xz}$ and $d_{yz}$ orbitals. Differences of detail in the
+predictions of the two methods are analyzed. This work is theoretically
+important as it presents the first application of the Auxiliary Field Quantum
+Monte Carlo method to an orbitally-degenerate system with both Mott and Hunds
+physics, and provides an important comparison of the Dynamical Mean Field and
+Auxiliary Field Quantum Monte Carlo methods.",1911.02702v1
+2019-11-25,Phase Instability amid Dimensional Crossover in Artificial Oxide Crystal,"Artificial crystals synthesized by atomic-scale epitaxy provides the ability
+to control the dimensions of the quantum phases and associated phase
+transitions via precise thickness modulation. In particular, reduction in
+dimensionality via quantized control of atomic layers is a powerful approach to
+revealing hidden electronic and magnetic phases. Here, we demonstrate a
+dimensionality-controlled and induced metal-insulator transition (MIT) in
+atomically designed superlattices by synthesizing a genuine two dimensional
+(2D) SrRuO3 crystal with highly suppressed charge transfer. The tendency to
+ferromagnetically align the spins in SrRuO3 layer diminishes in 2D as the
+interlayer exchange interaction vanishes, accompanying the 2D localization of
+electrons. Furthermore, electronic and magnetic instabilities in the two SrRuO3
+unit cell layers induce a thermally-driven MIT along with a metamagnetic
+transition.",1911.10665v1
+2020-03-03,Parabolic diamond scanning probes for single spin magnetic field imaging,"Enhancing the measurement signal from solid state quantum sensors such as the
+nitrogen-vacancy (NV) center in diamond is an important problem for sensing and
+imaging of condensed matter systems. Here we engineer diamond scanning probes
+with a truncated parabolic profile that optimizes the photonic signal from
+single embedded NV centers, forming a high-sensitivity probe for nanoscale
+magnetic field imaging. We develop a scalable fabrication procedure based on
+dry etching with a flowable oxide mask to reliably produce a controlled tip
+curvature. The resulting parabolic tip shape yields a median saturation count
+rate of 2.1 $\pm$ 0.2 MHz, the highest reported for single NVs in scanning
+probes to date. Furthermore, the structures operate across the full NV
+photoluminescence spectrum, emitting into a numerical aperture of 0.46 and the
+end-facet of the truncated tip, located near the focus of the parabola, allows
+for small NV-sample spacings and nanoscale imaging. We demonstrate the
+excellent properties of these diamond scanning probes by imaging ferromagnetic
+stripes with a spatial resolution better than 50 nm. Our results mark a 5-fold
+improvement in measurement signal over the state-of-the art in scanning-probe
+based NV sensors.",2003.01733v1
+2020-03-06,Mössbauer parameters of $^{57}$Fe substituents in the topological insulator $Bi_2Se_3$,"$^{57}$Fe M\""ossbauer spectroscopy can probe several \emph{local} structural,
+electronic and magnetic properties of Fe-containing systems. However, to
+establish a direct relationship between these properties and a system's
+geometric structure, the experimental M\""ossbauer parameters need to be
+analyzed \emph{via} electronic structure calculations. Herein, structural,
+electronic and magnetic effects of iron substituents in the topological
+insulator $Bi_2Se_3$, as uniquely probed by $^{57}$Fe M\""ossbauer spectroscopy,
+have been determined \emph{via} spin-polarized electronic structure
+calculations. The iron ion substituents, of \emph{nominal} Fe$^{3+}(S = 5/2)$
+oxidation and spin state, are unequivocally shown to substitute Bi$^{3+}$ sites
+in epitaxial $Bi_2Se_3$ thin-films used for M\""ossbauer measurements.
+Concomitant with iron substitution, \emph{localized} structural rearrangements
+take place whereby the longer Bi-Se bonds of the native system are replaced by
+significantly shorter Fe-Se counterparts in the Fe-containing system. The
+resulting distorted-octahedral environment about substituent iron ions gives
+rise to characteristic M\""ossbauer parameters ($\delta_{Fe} \approx$ 0.51 mm/s,
+$\Delta E_{Q} \approx$ 0.20 mm/s) which have been calculated in excellent
+agreement with measured values for Fe-doped $Bi_2Se_3$ thin films. Consistent
+with a substituent Fe$^{3+}$ ion's \emph{nominal} high-spin electronic
+configuration ($t_{2g}^{\uparrow \uparrow \uparrow} e_g^{\uparrow \uparrow}$),
+an Fe-centered spin density has been established which, nevertheless, extends
+towards neighboring Se atoms \emph{via} direct Fe-Se bonding and concomitant
+Fe(d)-Se(p) hybridization.",2003.03458v1
+2020-03-16,Spin orbit field in a physically defined p type MOS silicon double quantum dot,"We experimentally and theoretically investigate the spin orbit (SO) field in
+a physically defined, p type metal oxide semiconductor double quantum dot in
+silicon. We measure the magnetic field dependence of the leakage current
+through the double dot in the Pauli spin blockade. A finite magnetic field
+lifts the blockade, with the lifting least effective when the external and SO
+fields are parallel. In this way, we find that the spin flip of a tunneling
+hole is due to a SO field pointing perpendicular to the double dot axis and
+almost fully out of the quantum well plane. We augment the measurements by a
+derivation of SO terms using group symmetric representations theory. It
+predicts that without in plane electric fields (a quantum well case), the SO
+field would be mostly within the plane, dominated by a sum of a Rashba and a
+Dresselhaus like term. We, therefore, interpret the observed SO field as
+originated in the electric fields with substantial in plane components.",2003.07079v2
+2020-05-16,Vacancy-driven non-cubic local structure and magnetic anisotropy tailoring in Fe$_x$O-Fe$_{3-δ}$O$_4$ nanocrystals,"In contrast to bulk materials, nanoscale crystal growth is critically
+influenced by size- and shape-dependent properties. However, it is challenging
+to decipher how stoichiometry, in the realm of mixed-valence elements, can act
+to control physical properties, especially when complex bonding is implicated
+by short and long-range ordering of structural defects. Here, solution-grown
+iron-oxide nanocrystals (NCs) of the pilot wustite system are found to convert
+into iron-deficient rock-salt and ferro-spinel sub-domains, but attain a
+surprising tetragonally distorted local structure. Cationic vacancies within
+chemically uniform NCs are portrayed as the parameter to tweak the underlying
+properties. These lattice imperfections are shown to produce local
+exchange-anisotropy fields that reinforce the nanoparticles magnetization and
+overcome the influence of finite-size effects. The concept of atomic-scale
+defect control in subcritical size NCs, aspires to become a pathway to
+tailor-made properties with improved performance for hyperthermia heating over
+defect-free NCs.",2005.07947v1
+2020-06-30,Magnetic exchange coupling in cuprate-analog $d^9$ nickelates,"Motivated by the recent discovery of superconductivity in doped NdNiO$_2$, we
+study the magnetic exchange interaction $J$ in layered $d^9$ nickelates from
+first principles. The mother compounds of the high-$T_{\rm c}$ cuprates belong
+to the charge-transfer regime in the Zaanen-Sawatzky-Allen diagram and have $J$
+larger than 100 meV. While this feature makes the cuprates very different from
+other transition metal oxides, it is of great interest whether layered $d^9$
+nickelates can also have such a large $J$. However, one complexity is that
+NdNiO$_2$ is not a Mott insulator due to carrier doping from the block layer.
+To compare the cuprates and $d^9$ nickelates on an equal basis, we study
+RbCa$_2$NiO$_3$ and $A_{2}$NiO$_{2}$Br$_2$ ($A$: a cation with the valence of
+$2.5+$), which were recently designed theoretically by block-layer engineering.
+These nickelates are free from the self-doping effect and belong to the
+Mott-Hubbard regime. We show that these nickelates share a common thread with
+the high-$T_{\rm c}$ cuprates in that they also have a significant exchange
+interaction $J$ as large as about 100 meV.",2006.16943v3
+2021-03-29,Surface NMR using quantum sensors in diamond,"Characterization of the molecular properties of surfaces under ambient or
+chemically reactive conditions is a fundamental scientific challenge. Moreover,
+many traditional analytical techniques used for probing surfaces often lack
+dynamic or molecular selectivity, which limits their applicability for
+mechanistic and kinetic studies under realistic chemical conditions. Nuclear
+magnetic resonance spectroscopy (NMR) is a widely used technique and would be
+ideal for probing interfaces due to the molecular information it provides
+noninvasively. However, it lacks the sensitivity to probe the small number of
+spins at surfaces. Here, we use nitrogen vacancy (NV) centers in diamond as
+quantum sensors to optically detect nuclear magnetic resonance signals from
+chemically modified aluminum oxide surfaces, prepared with atomic layer
+deposition (ALD). With the surface NV-NMR technique, we are able to monitor in
+real-time the formation kinetics of a self assembled monolayer (SAM) based on
+phosphonate anchoring chemistry to the surface. This demonstrates the
+capability of quantum sensors as a new surface-sensitive tool with
+sub-monolayer sensitivity for in-situ NMR analysis with the additional
+advantage of a strongly reduced technical complexity.",2103.15955v1
+2021-03-30,Competing correlated states around the zero field Wigner crystallization transition of electrons in two-dimensions,"The competition between kinetic energy and Coulomb interactions in electronic
+systems can lead to complex many-body ground states with competing
+superconducting, charge density wave, and magnetic orders. Here we study the
+low temperature phases of a strongly interacting zinc-oxide-based high mobility
+two dimensional electron system that displays a tunable metal-insulator
+transition. Through a comprehensive analysis of the dependence of electronic
+transport on temperature, carrier density, in-plane and perpendicular magnetic
+fields, and voltage bias, we provide evidence for the existence of competing
+correlated metallic and insulating states with varying degrees of spin
+polarization. Our system features an unprecedented level of agreement with the
+state-of-the-art Quantum Monte Carlo phase diagram of the ideal jellium model,
+including a Wigner crystallization transition at a value of the interaction
+parameter $r_s\sim 30$ and the absence of a pure Stoner transition. In-plane
+field dependence of transport reveals a new low temperature state with partial
+spin polarization separating the spin unpolarized metal and the Wigner crystal,
+which we examine against possible theoretical scenarios such as an
+anti-ferromagnetic crystal, Coulomb induced micro-emulsions, and disorder
+driven puddle formation.",2103.16586v1
+2021-05-06,Growth and Characterisation Studies of Eu$_3$O$_4$ Thin Films Grown on Si/SiO$_2$ and Graphene,"We report the growth, structural and magnetic properties of the less studied
+Eu-oxide phase, Eu$_3$O$_4$, thin films grown on a Si/SiO$_2$ substrate and
+Si/SiO$_2$/graphene using molecular beam epitaxy. The X-ray diffraction scans
+show that highly-textured crystalline Eu$_3$O$_4$(001) films are grown on both
+substrates, whereas the film deposited on graphene has a better crystallinity
+than that grown on the Si/SiO$_2$ substrate. The SQUID measurements show that
+both films have a Curie temperature of about 5.5 K, with a magnetic moment of
+0.0032 emu/g at 2 K. The mixed-valency of the Eu cations has been confirmed by
+the qualitative analysis of the depth-profile X-ray photoelectron spectroscopy
+measurements with the Eu$^{2+}$ : Eu$^{3+}$ ratio of 28 : 72. However,
+surprisingly, our films show no metamagnetic behaviour as reported for the bulk
+and powder form. Furthermore, the Raman spectroscopy scans show that the growth
+of the Eu$_3$O$_4$ thin films has no damaging effect on the underlayer graphene
+sheet. Therefore, the graphene layer is expected to retain its properties.",2105.02705v1
+2021-05-10,Observation of the Orbital Rashba-Edelstein Magnetoresistance,"We report the observation of magnetoresistance (MR) originating from the
+orbital angular momentum transport (OAM) in a Permalloy (Py) / oxidized Cu
+(Cu*) heterostructure: the orbital Rashba-Edelstein magnetoresistance. The
+angular dependence of the MR depends on the relative angle between the induced
+OAM and the magnetization in a similar fashion as the spin Hall
+magnetoresistance (SMR). Despite the absence of elements with large spin-orbit
+coupling, we find a sizable MR ratio, which is in contrast to the conventional
+SMR which requires heavy elements. By varying the thickness of the Cu* layer,
+we confirm that the interface is responsible for the MR, suggesting that the
+orbital Rashba-Edelstein effect is responsible for the generation of the OAM.
+Through Py thickness-dependence studies, we find that the effective values for
+the spin diffusion and spin dephasing lengths of Py are significantly larger
+than the values measured in Py / Pt bilayers, approximately by the factor of 2
+and 4, respectively. This implies that another mechanism beyond the
+conventional spin-based scenario is responsible for the MR observed in Py / Cu*
+structures originated in a sizeable transport of OAM. Our findings not only
+unambiguously demonstrate the current-induced torque without using any heavy
+element via the OAM channel but also provide an important clue towards the
+microscopic understanding of the role that OAM transport can play for
+magnetization dynamics.",2105.04495v2
+2021-06-03,Oxygen out-diffusion in REBCO coated conductor due to heating,"Rare earth barium copper oxide (REBCO) coated conductor has emerged as one of
+the high Tc superconductors suitable for future ultrahigh field superconducting
+magnet applications. In the design and fabrication of such ultrahigh field
+REBCO magnets, it is essential to understand the behavior of REBCO coated
+conductor. The effect of heating on the properties of commercial REBCO coated
+conductors is very important for many practical reasons. Nevertheless, a
+comprehensive study on this effect have not yet been presented in the published
+literature. This work studies a commercial REBCO coated conductor heat-treated
+at temperatures between 175 {\deg}C and 300 {\deg}C for various durations.
+Critical current and lap joint resistivity were measured at 77 K and 4.2 K for
+the heat-treated samples. We found that critical current degrades with heat
+treatment time and temperature. This degradation can be described by a
+one-dimensional oxygen out-diffusion model with a diffusion coefficient of D =
+2.5 x 10-6 exp (-1.17 eV/kT) m2/s. The heat treatment also causes appreciable
+increase in joint resistivity. Comprehensive structural and chemical analyses
+were performed on Cu/Ag/RECBO interfaces by transmission electron microscopy
+(TEM). Our electron energy loss spectroscopy (EELS) study provided direct
+evidence of oxygen deficiency in the heat treated REBCO samples. In addition,
+it is found that the oxygen diffused out of the REBCO layer forms mostly Cu2O
+at both Ag/REBCO and Cu/Ag interfaces. Cu2O is also observed at grain
+boundaries of the Ag layer. The oxygen out-diffusion model proposed in this
+work is used to predict REBCO thermal degradation in several engineering
+scenarios.",2106.01905v1
+2021-06-08,"Superconducting microresonators for electron spin resonance, the good, the bad, and the future","The field of electron spin resonance is in constant need to improve its
+capabilities. Among other things, this means having better resonators which
+would provide improved spin sensitivity, as well as enable larger microwave
+magnetic field power conversion factors. Surface micro resonators, made of
+small metallic patches on a dielectric substrate, provide very good absolute
+spin sensitivity and high conversion factors due to their very small mode
+volume. However, such resonators suffer from having a relatively low quality
+factor, which offsets some of their significant potential advantages. The use
+of superconducting patches to replace the metallic layer seems like a
+reasonable and straightforward solution to the quality factor issue, at least
+for measurements carried out at cryogenic temperatures. Nevertheless,
+superconducting materials are not easily incorporated into setups requiring
+high magnetic fields, due to electric current vortices generated in the
+latter's surface. This makes the transition from normal conducing materials to
+superconductors highly nontrivial. Here we present the design, fabrication, and
+testing results of surface micro resonators made of yttrium barium copper oxide
+(YBCO) superconducting material. We show that with a unique experimental setup,
+these resonators can be made to operate well even at high fields of about 1.2
+T. Furthermore, we analyze the effect of current vortices on the ESR signal and
+the spins' coherence times. Finally, we provide a head to head comparison of
+YBCO vs copper resonators of the same dimensions, which clearly shows their
+pros and cons and directs us to future potential developments and improvements
+in this field.",2106.04163v2
+2021-06-18,"Growth and characterization of large (Y,La)TiO$_3$ and (Y,Ca)TiO$_3$ single crystals","The Mott-insulating rare-earth titanates (RTiO$_3$, R being a rare-earth ion)
+are an important class of materials that encompasses interesting spin-orbital
+phases as well as ferromagnet-antiferromagnet and insulator-metal transitions.
+The growth of these materials has been plagued by difficulties related to
+overoxidation, which arises from a strong tendency of Ti$^{3+}$ to oxidize to
+Ti$^{4+}$. We describe our efforts to grow sizable single crystals of YTiO$_3$
+and its La-substituted and Ca-doped variants with the optical
+travelling-solvent floating-zone technique. We present sample characterization
+$via$ chemical composition analysis, magnetometry, charge transport, neutron
+scattering, x-ray absorption spectroscopy and x-ray magnetic circular dichroism
+to understand macroscopic physical property variations associated with
+overoxidation. Furthermore, we demonstrate a good signal-to-noise ratio in
+inelastic magnetic neutron scattering measurements of spin-wave excitations. A
+superconducting impurity phase, found to appear in Ca-doped samples at high
+doping levels, is identified as TiO.",2106.10253v1
+2021-07-06,Structural modulation in potassium birnessite single crystals,"We report on the growth of single-crystal potassium birnessite
+(K0.31MnO2*0.41H2O) and present both the average and local structural
+characterization of this frustrated magnetic system. Single crystals were
+obtained employing a flux growth method with a KNO3/B2O3 flux at 700 {\deg}C.
+Single-crystal X-ray diffraction revealed an average orthorhombic symmetry,
+with space group Cmcm. A combination of high angle annular dark field scanning
+transmission electron microscopy (HAADF-STEM) with atomic resolution energy
+dispersive X-ray spectroscopy (EDS) demonstrated the layered structure of
+potassium birnessite with manganese-containing planes well separated by layers
+of potassium atoms. MnO6 octahedra and the K/H2O planes were clearly imaged via
+integrated differential phase contrast (iDPC) STEM. Furthermore, iDPC-STEM also
+revealed the existence of local domains with alternating contrast of the
+manganese oxide planes, most likely originating from charge ordering of Mn3+
+and Mn4+ along the c-axis. These charge-ordered domains are clearly correlated
+with a reduction in the c-lattice parameter compared to the rest of the matrix.
+The insight gained from this work allows for a better understanding of the
+correlation between structure and magnetic properties.",2107.02880v1
+2021-09-26,Electronic phase separation: recent progress in the old problem,"We consider the nanoscale electronic phase separation in a wide class of
+different materials, mostly in strongly correlated electron systems. The phase
+separation turns out to be quite ubiquitous manifesting itself in different
+situations, where the itineracy of charge carriers competes with their tendency
+toward localization. The latter is often related to some specific type of
+magnetic ordering, e.g. antiferromagnetic in manganites and low-spin states in
+cobaltites. The interplay between the localization-induced lowering of
+potential energy and metallicity (which provides the gain in the kinetic
+energy) favors an inhomogeneous ground state such as nanoscale ferromagnetic
+droplets in an antiferromagnetic insulating background. The present review
+article deals with the advances in the subject of electronic phase separation
+and formation of different types of nanoscale ferromagnetic (FM) metallic
+droplets (FM polarons or ferrons) in antiferromagnetically ordered (AFM),
+charge-ordered (CO), or orbitally-ordered (OO) insulating matrices, as well as
+the colossal magnetoresistance (CMR) effect and tunneling electron transport in
+the nonmetallic phase-separated state of complex magnetic oxides. It also
+touches upon the compounds with spin-state transitions, inhomogeneous
+phase-separated state in strongly correlated multiband systems, and electron
+polaron effect. A special, attention is paid to the systems with the imperfect
+Fermi surface nesting such as chromium alloys, iron-based pnictides, and AA
+stacked graphene bilayers.",2109.12684v2
+2021-11-11,Current-induced superconducting anisotropy of Sr$\mathsf{_2}$RuO$\mathsf{_4}$,"In the unconventional superconductor Sr$\mathsf{_2}$RuO$\mathsf{_4}$, unusual
+first-order superconducting transition has been observed in the low-temperature
+and high-field region, accompanied by a four-fold anisotropy of the in-plane
+upper critical magnetic field $H_{c2}$. The origin of such unusual $H_{c2}$
+behavior should be closely linked to the debated superconducting symmetry of
+this oxide. Here, toward clarification of the unusual $H_{c2}$ behavior, we
+performed the resistivity measurements capable of switching in-plane current
+directions as well as precisely controlling the field directions. Our results
+reveal that resistive $H_{c2}$ under the in-plane current exhibits an
+additional two-fold anisotropy. By systematically analyzing $H_{c2}$ data taken
+under various current directions, we succeeded in separating the two-fold
+$H_{c2}$ component into the one originating from applied current and the other
+originating from certain imperfection in the sample. The former component,
+attributable to vortex flow effect, is weakened at low temperatures where
+$H_{c2}$ is substantially suppressed. The latter component is enhanced in the
+first order transition region, possibly reflecting a change in the nature of
+the superconducting state under high magnetic field.",2111.06097v1
+2021-11-23,Li-ion diffusion in single crystal LiFePO$_4$ measured by muon spin spectroscopy,"Muon spin spectroscopy ($\mu^+$SR) is now an established method to measure
+atomic scale diffusion coefficients of ions in oxides. This is achieved via the
+ion hopping rate, which causes periodic change in the local magnetic field at
+the muon site(s). We present here the first systematic study on a single
+crystalline sample. The highly anisotropic diffusion of Li-ions in the battery
+cathode material LiFePO$_4$, combined with the extensive investigation of this
+material with $\mu^+$SR and other techniques make it a perfect model compound
+for this study. With this experiment we can confirm that Li diffusion in the
+bulk LiFePO$_4$ is measurable with $\mu^+$SR. Hence, surface/interface effects,
+which might play a crucial role in case of powders/nano crystals, are less
+significant for macroscopic single crystals where bulk diffusion is in fact
+present. We observe that the internal magnetic field fluctuations caused by the
+diffusing Li-ions are different depending on the crystal orientation. This is
+not obviously expected based on theoretical considerations. Such fluctuation
+rates were used to estimate the diffusion coefficient, which agrees well with
+values estimated by first principle calculations considering anisotropic
+diffusion.",2111.11941v1
+2022-01-16,Physical realization of topological Roman surface by spin-induced ferroelectric polarization in cubic lattice,"Topology, a mathematical concept in geometry, has become an ideal theoretical
+tool for describing topological states and phase transitions. Many topological
+concepts have found their physical entities in real or reciprocal spaces
+identified by topological/geometrical invariants, which are usually defined on
+orientable surfaces such as torus and sphere. It is natural to quest whether it
+is possible to find the physical realization of more intriguing non-orientable
+surfaces. Herein, we show that the set of spin-induced ferroelectric
+polarizations in cubic perovskite oxides AMn3Cr4O12 (A = La and Tb) resides on
+the topological Roman surface, a non-orientable two-dimensional manifold formed
+by sewing a Mobius strip edge to that of a disc. The induced polarization may
+travel in a loop along the non-orientable Mobius strip or orientable disc
+depending on how the spin evolves as controlled by external magnetic field.
+Experimentally, the periodicity of polarization can be the same or the twice of
+the rotating magnetic field, being well consistent with the orientability of
+disc and Mobius strip, respectively. This path dependent topological
+magnetoelectric effect presents a way to detect the global geometry of the
+surface and deepens our understanding of topology in both mathematics and
+physics",2201.06018v1
+2022-04-08,Quantum Dots / Spin Qubits,"Spin qubits in semiconductor quantum dots represent a prominent family of
+solid-state qubits in the effort to build a quantum computer. They are formed
+when electrons or holes are confined in a static potential well in a
+semiconductor, giving them a quantized energy spectrum. The simplest spin qubit
+is a single electron spin located in a quantum dot, but many additional
+varieties have been developed, some containing multiple spins in multiple
+quantum dots, each of which has different benefits and drawbacks. While these
+spins act as simple quantum systems in many ways, they also experience complex
+effects due to their semiconductor environment. They can be controlled by both
+magnetic and electric fields depending on their configuration and are therefore
+dephased by magnetic and electric field noise, with different types of spin
+qubits having different control mechanisms and noise susceptibilities. While
+initial experiments were primarily performed in gallium arsenide (GaAs) based
+materials, silicon qubits have developed substantially and research on qubits
+in metal-oxide-semiconductor (Si-MOS), silicon/silicon germanium (Si/SiGe)
+heterostructures, and donors in silicon is also being pursued. An increasing
+number of spin qubit varieties have attained error rates that are low enough to
+be compatible with quantum error correction for single-qubit gates and
+two-qubit gates have been performed in several with success rates, or
+fidelities, of 90-95%.",2204.04261v1
+2022-05-06,Magnetic frustration in the cubic double perovskite Ba2NiIrO6,"Hybrid transition metal oxides continue to attract attention due to their
+multiple degrees of freedom ($e.g.$, lattice, charge, spin, and orbital) and
+versatile properties. Here we investigate the magnetic and electronic
+properties of the newly synthesized double perovskite Ba$_2$NiIrO$_6$, using
+crystal field theory, superexchange model analysis, density functional
+calculations, and parallel tempering Monte Carlo (PTMC) simulations. Our
+results indicate that Ba$_2$NiIrO$_6$ has the Ni$^{2+}$
+($t_{2g}^{6}e_{g}^{2}$)-Ir$^{6+}$ ($t_{2g}^{3}$) charge states. The first
+nearest-neighboring (1NN) Ni$^{2+}$-Ir$^{6+}$ ions prefer a ferromagnetic (FM)
+coupling as expected from the Goodenough-Kanamori-Anderson rules, which
+contradicts the experimental antiferromagnetic (AF) order in Ba$_2$NiIrO$_6$.
+We find that the strong 2NN AF couplings are frustrated in the fcc sublattices,
+and they play a major role in determining the observed AF ground state. We also
+prove that the $J_{\rm eff}$ = 3/2 and $J_{\rm eff}$ = 1/2 states induced by
+spin-orbit coupling, which would be manifested in low-dimensional (e.g.,
+layered) iridates, are however not the case for cubic Ba$_2$NiIrO$_6$. Our PTMC
+simulations show that when the long-range (2NN and 3NN) AF interactions are
+included, an AF transition with $T_{\rm N}$ = 66 K would be obtained and it is
+well comparable with the experimental 51 K. Meanwhile, we propose a possible
+2$\times$2$\times$2 noncollinear AF structure for Ba$_2$NiIrO$_6$.",2205.03049v1
+2022-05-14,Anomalous metallic oxygen band in the potential superconductor KCa$_2$Fe$_4$As$_4$O$_2$,"The electronic structure, magnetism and Fermi surface of a hole self-doped
+potential iron-based superconductor KCa$_2$Fe$_4$As$_4$O$_2$ (12442) were
+studied by a first-principes DFT/GGA approach. The projection onto Wannier
+functions basis is proposed to calculate directly the self-doping value. In
+particular for KCa$_2$Fe$_4$As$_4$O$_2$ it is 0.75 hole on Fe-3d states.
+Surprisingly, for the KCa$_2$Fe$_4$As$_4$O$_2$ it was found that except the
+Fe-3d bands the O-2p bands also cross the Fermi level, which is quite anomalous
+behavior for O-2p states. In general, the O-2p states are usually fully
+occupied in transition metal oxides. Here it is not the case due to the fact
+that CaO layer gives some of the electrons to the FeAs layer, thus leaving O-2p
+states partially occupied. The O-2p states form additional Fermi surface sheet
+with propeller-like shape around $\Gamma$-point and modify the Fe-3d Fermi
+surface sheets due to the hybridization. To prove the presence of anomalous
+metallic O-2p band in KCa$_2$Fe$_4$As$_4$O$_2$ the comparative study with the
+same family systems KCa$_2$Fe$_4$As$_4$F$_2$ and RbGd$_2$Fe$_4$As$_4$O$_2$
+(where it is not the case) was performed. The magnetic ground state is found to
+be antiferromagnetic with checkerboard ordering. Therefore, we expect that the
+KCa$_2$Fe$_4$As$_4$O$_2$ might be a potential superconductor with unusual
+properties.",2205.07007v1
+2022-08-23,Topotactic-hydrogen forms chains in $AB$O$_2$ nickelate superconductors,"Despite enormous experimental and theoretical efforts, obtaining generally
+accepted conclusions regarding the intrinsic magnetic and electronic properties
+of superconducting nickelates remains exceptionally challenging. Experiments
+show a significant degree of uncertainty, indicating hidden factors in the
+synthesized films, which call for further investigations. One of those ""hidden
+factors"" is the possibility of intercalating hydrogen during the chemical
+reduction process from Nd(La)NiO$_3$ to Nd(La)NiO$_2$ using CaH$_2$. While
+hydrogen has been detected in experimental samples, not much is known about its
+distribution through the crystal and its influence on the electronic
+environment. Here, we show the tendency toward the formation of one-dimensional
+hydrogen chains in infinite-layers LaNiO$_2$ superconductors using
+density-functional theory (DFT) supplemented by dynamical mean-field theory
+(DMFT). The formation of such hydrogen chains induces a coexistence of
+different oxidation states of Ni and competing magnetic phases, and possibly
+explains the recently observed charge order states in nickelate
+superconductors. Furthermore, it contributes to the difficulty of synthesizing
+homogeneous nickelates and determining their ground states. The smoking gun to
+detect excess hydrogen in nickelates are flat phonon modes, which are infrared
+active and quite insensitive to the exact arrangement of the H atoms.",2208.11085v2
+2022-11-30,A proposal for leaky integrate-and-fire neurons by domain walls in antiferromagnetic insulators,"Brain-inspired neuromorphic computing is a promising path towards next
+generation analogue computers that are fundamentally different compared to the
+conventional von Neumann architecture. One model for neuromorphic computing
+that can mimic the human brain behavior are spiking neural networks (SNNs), of
+which one of the most successful is the leaky integrate-and-fire (LIF) model.
+Since conventional complementary metal-oxide-semiconductor (CMOS) devices are
+not meant for modelling neural networks and are energy inefficient in network
+applications, recently the focus shifted towards spintronic-based neural
+networks. In this work, using the advantage of antiferromagnetic insulators, we
+propose a non-volatile magnonic neuron that could be the building block of a
+LIF spiking neuronal network. In our proposal, an antiferromagnetic domain wall
+in the presence of a magnetic anisotropy gradient mimics a biological neuron
+with leaky, integrating, and firing properties. This single neuron is
+controlled by polarized antiferromagnetic magnons, activated by either a
+magnetic field pulse or a spin transfer torque mechanism, and has properties
+similar to biological neurons, namely latency, refraction, bursting and
+inhibition. We argue that this proposed single neuron, based on
+antiferromagnetic domain walls, is faster and has more functionalities compared
+to previously proposed neurons based on ferromagnetic systems.",2211.16845v2
+2022-12-27,"Interrelations among critical current density, irreversibility field and pseudogap in hole doped high-Tc cuprates","The effects of hole content (p) and oxygen deficiency (delta) on the
+zero-field critical current density, Jc0, were investigated for high-quality
+c-axis oriented Y1-xCaxBa2Cu3O7-delta (x = 0, 0.05, 0.10, and 0.20) thin films.
+Low temperature critical current density of these films above the optimum
+doping were found to be high and were primarily determined by the hole
+concentration, reaching a maximum at p ~ 0.185 +/- 0.005, irrespective of the
+level of oxygen deficiency. This implies that oxygen disorder plays only a
+secondary role and the intrinsic Jc0 is primarily governed by the carrier
+concentration in the copper oxide planes. Further support in favor of this was
+found from the analysis of the in-plane resistive transitions of c-axis
+oriented crystalline thin films of YBa2Cu3O7-delta (YBCO) under magnetic fields
+(H) applied along the c-direction, over a wide range of doped holes. The
+characteristic magnetic field (H0), linked to the vortex activation energy and
+the irreversibility field, exhibits similar p-dependence as shown by Jc0(p). We
+have explained these observations in terms of the doping dependent pseudogap
+(PG) in the low-energy electronic energy density of states. Both the intrinsic
+critical current density and the irreversibility field depend directly on the
+superconducting condensation energy, which in turn is largely controlled by the
+magnitude of the hole concentration dependent PG in the quasiparticle spectral
+density.",2212.13339v1
+2023-02-01,From a superconductor NdNiO$_2$ to a Mott multiferroic BiNiO$_2$,"Motivated by the recently discovered superconductivity in Sr-doped nickelate
+oxides NdNiO$_2$, we predict a material BiNiO$_2$ that provides an opportunity
+to study the intertwined ferroelectricity, metallicity, and magnetism in a
+crystal with very simple atomic structures. There is a ferroelectric structural
+transition from the nonpolar phase with the P4/mmm space group to the polar
+phase with the P4mm space group, which is driven by the lone pair on Bi.
+Calculations based on the Heyd-Scuseria-Ernzerhof hybrid density functional
+reveal that both the nonmagnetic and ferromagnetic states are metallic for
+nonpolar and polar phases, while the lowest energy ground-state for polar
+BiNiO$_2$ is a Hubbard Mott insulator with the G-type antiferromagnetic spin
+configurations. As a ferroelectric material with an electric polarization of
+0.49 C/m2, it may be possible to control the magnetic order in BiNiO$_2$ by an
+applied electric field. The replacement of Nd by Bi serves as a connecting link
+between a high-temperature superconductor and a Mott multiferroic. Our work
+supports a route towards strongly correlated ferroelectrics.",2302.00172v1
+2023-02-19,Hysteresis and training effect in the electric control of spin current in Pt/Y3Fe5O12 heterostructures,"We have reported on the hysteresis and training effect of spin current in
+Pt/Y3Fe5O12 heterostructures during subsequent cycles of ionic liquid gate
+voltage Vg. The inverse spin Hall effect voltage in spin pumping and spin Hall
+magnetoresistance exhibit diode-like behaviors in the first half cycle of Vg
+andalsoshowhysteresisinthe first cycle of Vg. Both the diode-like behavior and
+the hysteresis become weak and even vanish in the second cycle of Vg due to the
+training effect. The above experimental results can be well explained by the
+screening charge doping model, in which the charge and the local magnetic
+moment are asymmetrically distributed in the Pt layer. The applicability of
+this model is further confirmed by measurements of anisotropic
+magnetoresistance and ferromagnetic resonance. The diode-like behavior is
+attributed to interplay between the asymmetrically distributed local magnetic
+moment and the spin current relaxation in the Pt layer. The hysteresis and the
+training effect arise from the incompletely reversible process between
+oxidation and reduction of Pt atoms and the evolution of the surface morphology
+at the ionic liquid/Pt interface under electric gating. This work provides new
+insights to improve the functional performance of electrically controlled spin
+current devices.",2302.09505v1
+2023-04-03,Nonrelativistic and nonmagnetic control of terahertz charge currents via electrical anisotropy in RuO2 and IrO2,"Precise and ultrafast control over photo-induced charge currents across
+nanoscale interfaces could lead to important applications in energy harvesting,
+ultrafast electronics, and coherent terahertz sources. Recent studies have
+shown that several relativistic mechanisms, including inverse spin-Hall effect,
+inverse Rashba-Edelstein effect and inverse spin-orbit-torque effect, can
+convert longitudinally injected spin-polarized currents from magnetic materials
+to transverse charge currents, thereby harnessing these currents for terahertz
+generation. However, these mechanisms typically require external magnetic
+fields and suffer from low spin-polarization rates and low efficiencies of
+relativistic spin-to-charge conversion. In this work, we present a novel
+nonrelativistic and nonmagnetic mechanism that directly utilizes the
+photo-excited high-density charge currents across the interface. We demonstrate
+that the electrical anisotropy of conductive oxides RuO2 and IrO2 can
+effectively deflect injected charge currents to the transverse direction,
+resulting in efficient and broadband terahertz radiation. Importantly, this new
+mechanism has the potential to offer much higher conversion efficiency compared
+to previous methods, as conductive materials with large electrical anisotropy
+are readily available, whereas further increasing the spin-Hall angle of
+heavy-metal materials would be challenging. Our new findings offer exciting
+possibilities for directly utilizing these photo-excited high-density currents
+across metallic interfaces for ultrafast electronics and terahertz
+spectroscopy.",2304.00692v1
+2023-04-13,Direct experimental evidence of tunable charge transfer at the $LaNiO_{3}/CaMnO_{3}$ ferromagnetic interface,"Interfacial charge transfer in oxide heterostructures gives rise to a rich
+variety of electronic and magnetic phenomena. Designing heterostructures where
+one of the thin-film components exhibits a metal-insulator transition opens a
+promising avenue for controlling such phenomena both statically and
+dynamically. In this letter, we utilize a combination of depth-resolved soft
+X-ray standing-wave and hard X-ray photoelectron spectroscopies in conjunction
+with polarization-dependent X-ray absorption spectroscopy to investigate the
+effects of the metal-insulator transition in $LaNiO_{3}$ on the electronic and
+magnetic states at the $LaNiO_{3}/CaMnO_{3}$ interface. We report on a direct
+observation of the reduced effective valence state of the interfacial Mn
+cations in the metallic superlattice with an above-critical $LaNiO_{3}$
+thickness (6 u.c.) due to the leakage of itinerant Ni 3d $e_{g}$ electrons into
+the interfacial $CaMnO_{3}$ layer. Conversely, in an insulating superlattice
+with a below-critical $LaNiO_{3}$ thickness of 2 u.c., a homogeneous effective
+valence state of Mn is observed throughout the $CaMnO_{3}$ layers due to the
+blockage of charge transfer across the interface. The ability to switch and
+tune interfacial charge transfer enables precise control of the emergent
+ferromagnetic state at the $LaNiO_{3}/CaMnO_{3}$ interface and, thus, has
+far-reaching consequences on the future strategies for the design of
+next-generation spintronic devices.",2304.06688v1
+2023-04-14,Recent advances in La2NiMnO6 Double Perovskites for various applications; Challenges and opportunities,"Double perovskites R2NiMnO6 (R= Rare earth element) (RNMO) are a significant
+class of materials owing to their Multifunctional properties with structural
+modifications. In particular, multifunctional double perovskite oxides
+La2NiMnO6 (LNMO) which possess both electric and magnetic orderings, chemical
+flexibility, versatility, and indispensable properties like high ferromagnetic
+curie temperature, high absorption rates, dielectrics, etc. have drawn a lot of
+attention due their rich physics and diverse applications in various
+technology. This justifies the intense research in this class of materials, and
+the keen interest they are subject to both the fundamental and practical side.
+In view of the demands of this material in lead-free perovskite solar cells,
+photocatalytic degradation of organic dyes, clean hydrogen production, electric
+tuneable devices, Fuel cells, gas sensing, and Biomedical applications, there
+is a need for an overview of all the literature so far, the ongoing research
+and the future prospective. This review summarised all the Physical and
+Structural Properties of LNMO such as electric, magnetic, catalytic, and
+dielectric properties with their underlying mechanisms. This review article
+provides insight into the scope of studies in LNMO material for exploring
+unexposed properties in new material research and to identify areas of future
+investigation of the materials in the double perovskite family.",2304.06951v1
+2023-06-16,Magneto-ionic modulation of the interlayer exchange interaction in synthetic antiferromagnets,"The electric-field control of magnetism is a highly promising and potentially
+effective approach for achieving energy-efficient applications. In recent
+times, there has been significant interest in the magneto-ionic effect in
+synthetic antiferromagnets, primarily due to its strong potential in the
+realization of high-density storage devices with ultra-low power consumption.
+However, the underlying mechanism responsible for the magneto-ionic effect on
+the interlayer exchange coupling (IEC) remains elusive. In this study, we have
+successfully identified that the magneto-ionic control of the properties of the
+top ferromagnetic layer of the synthetic antiferromagnet (SyAFM), which is in
+contact with the high ion mobility oxide, plays a pivotal role in driving the
+observed gate-induced changes to the IEC. Our findings provide crucial insights
+into the intricate interplay between stack structure and magnetoionic-field
+effect on magnetic properties in synthetic antiferromagnetic thin film systems.",2306.09888v1
+2023-08-18,Magnetoresistance anomaly during the electrical triggering of a metal-insulator transition,"Phase separation naturally occurs in a variety of magnetic materials and it
+often has a major impact on both electric and magnetotransport properties. In
+resistive switching systems, phase separation can be created on demand by
+inducing local switching, which provides an opportunity to tune the electronic
+and magnetic state of the device by applying voltage. Here we explore the
+magnetotransport properties in the ferromagnetic oxide (La,Sr)MnO3 (LSMO)
+during the electrical triggering of an intrinsic metal-insulator transition
+(MIT) that produces volatile resistive switching. This switching occurs in a
+characteristic spatial pattern, i.e., the formation of an insulating barrier
+perpendicular to the current flow, enabling an electrically actuated
+ferromagnetic-paramagnetic-ferromagnetic phase separation. At the threshold
+voltage of the MIT triggering, both anisotropic and colossal magnetoresistances
+exhibit anomalies including a large increase in magnitude and a sign flip.
+Computational analysis revealed that these anomalies originate from the
+coupling between the switching-induced phase separation state and the intrinsic
+magnetoresistance of LSMO. This work demonstrates that driving the MIT material
+into an out-of-equilibrium resistive switching state provides the means to
+electrically control of the magnetotransport phenomena.",2308.09260v2
+2023-10-23,First Chromospheric Activity and Doppler Imaging Study of PW And Using a New Doppler Imaging Code: SpotDIPy,"Measuring coverage of dark spots on cool stars is important in understanding
+how stellar magnetic activity scales with the rotation rate and convection zone
+depth. In this respect, it is crucial to infer surface magnetic patterns on G
+and K stars, to reveal solar-like stellar dynamos in action. Molecular bands
+serve as invaluable indicators of cool spots on the surfaces of stars, as they
+play a crucial role in enabling accurate assessments of the extent of spot
+coverage across the stellar surface. Therefore, more reliable surface images
+can be obtained considering the inversion of atomic lines with molecular bands.
+In this context, we simultaneously carry out Doppler imaging (DI) using atomic
+lines as well as Titanium Oxide (TiO) band profiles of PW And (K2 V) and also
+investigate chromospheric activity indicators for the first time in the
+literature, using the high-resolution spectra. The surface spot distribution
+obtained from the inversion process represents both atomic line and TiO-band
+profiles quite accurately. The chromospheric emission is also correlated with
+photospheric spot coverage, except during a possible flare event during the
+observations. We detect frequent flare activity, using TESS photometry. We also
+introduce a new open-source, Python-based DI code SpotDIPy that allows
+performing surface reconstructions of single stars using the maximum entropy
+method. We test the code by comparing surface reconstruction simulations with
+the extensively used DoTS code. We show that the surface brightness
+distribution maps reconstructed via both codes using the same simulated data
+are consistent with each other.",2310.14865v1
+2024-01-24,Mesoscale self-organization of polydisperse magnetic nanoparticles at the water surface,"In this study, we investigated the self-ordering process in Langmuir films of
+polydisperse iron oxide nanoparticles on a water surface, employing in-situ
+X-ray scattering, surface pressure-area isotherm analysis, and Brewster angle
+microscopy. X-ray reflectometry confirmed the formation of a monolayer, while
+grazing incidence small-angle X-ray scattering revealed short-range lateral
+correlations with a characteristic length equal to the mean particle size.
+Remarkably, our findings indicated that at zero surface pressure, the particles
+organized into submicrometer clusters, merging upon compression to form a
+homogeneous layer. These layers were subsequently transferred to a solid
+substrate using the Langmuir-Schaefer technique and further characterized via
+scanning electron microscopy and polarized neutron reflectometry. Notably, our
+measurements unveiled a second characteristic length in the lateral
+correlations, orders of magnitude longer than the mean particle diameter, with
+polydisperse particles forming circular clusters densely packed in a hexagonal
+lattice. Furthermore, our evidence suggested that the lattice constant of this
+mesocrystal depended on the characteristics of the particle size distribution,
+specifically the mean particle size and the width of the size distribution.
+Additionally, we observed internal size separation within these clusters, where
+larger particles were positioned closer to the center of the cluster. Finally,
+polarized neutron reflectometry measurements provided valuable insights into
+the magnetization profile across the layer.",2401.13768v1
+2024-01-26,Engineering strong magnetoelectricity using a hexagonal 2D material on electron-doped hexagonal LuFeO$_3$,"Cubic perovskite-structure ABO$_3$ and A$_{1-x}$A$^{\prime}$$_x$BO$_3$-type
+oxides have been investigated extensively while their hexagonal-structure
+versions have received minimal attention, even though they are multiferroic and
+can form heterostructures with the manifold hexagonal two-dimensional
+materials. Hexagonal ferrites of the form RFeO$_3$, where R is yttrium or a
+rare-earth element such as Lu, Yb, etc., feature coupled ferroelectricity (FE)
+and weak-ferromagnetism (wFM), exhibiting linear magnetoelectricity. Their only
+drawback is weak ferromagnetism. In this paper, we employ
+density-functional-theory (DFT) calculations on hexagonal LuFeO$_3$ ($h$-LFO),
+targeting its magnetic ordering by electron doping,anticipating
+spin-disproportionation of the Fe sublattices. Indeed, we show that
+spin-disproportionation in heavily-electron-doped versions
+Lu$_{1-x}$Hf$_x$FeO$_3$ ($h$-LHFO), especially for x=1/3 and 1/2, leads to
+robust out-of-plane collinear ferrimagnetism that is stable at room
+temperature. Furthermore, the robust ferroelectricity of $h$-LFO persists via a
+Jahn-Teller metal-to-insulator transition. Finally, we construct a
+$h$-LHFO/$h$-2D heterostructure, where $h$-2D stands for the FE/FM monolayer
+MnSTe, and demonstrate strong magnetoelectric coupling, namely manipulation of
+magnetic skyrmions in MnSTe by an external electric field through the $h$-LHFO
+polarization, opening up a new realm for magnetoelectric applications.",2401.15053v1
+2004-04-09,New beta-Pyrochlore Oxide Superconductor CsOs2O6,"The discovery of a new beta-pyrochlore oxide superconductor CsOs2O6 with Tc =
+3.3 K is reported. It is the third superconductor in the family of
+beta-pyrochlore oxides, following KOs2O6 with Tc = 9.6 K and RbOs2O6 with Tc =
+6.3 K. The Tc of this series decreases with increasing the ionic radius of
+alkaline metal ions, imposing negative chemical pressure upon the Os pyrochlore
+lattice.",0404220v1
+2006-05-11,First-Principles Modeling of Ferroelectric Oxide Nanostructures,"The aim of this Chapter is to provide an account of recent advances in the
+first-principles modeling of ferroelectric oxide nanostructures. Starting from
+a microscopic description of ferroelectricity in bulk materials and considering
+then, successively, different kinds of nanostructures (films, multilayers,
+wires, and particles), we try to identify the main trends and to provide a
+coherent picture of the role of finite size effects in ferroelectric oxides.",0605299v1
+2008-12-16,Electrical properties of vanadium oxide subject to hydrogen plasma treatment,"The effect of doping with hydrogen on the electrical properties of vanadium
+oxide is studied. For vanadium oxide films, subject to cold hydrogen plasma
+treatment, the temperature dependence of resistance with a maximum at T ~ 100 K
+is observed. Also, the dependence of the a.c. resistance on frequency is
+studied. A strategy for fabrication new superconducting materials is discussed.",0812.2973v1
+2009-10-07,An oxide thermal rectifier,"We have experimentally demonstrated thermal rectification as bulk effect.
+According to a theoretical design of a thermal rectifier, we have prepared an
+oxide thermal rectifier made of two cobalt oxides with different thermal
+conductivities, and have made an experimental system to detect the thermal
+rectification. The rectifying coefficient of the device is found to be 1.43,
+which is in good agreement with the numerical calculation.",0910.1153v1
+2011-02-18,Formation and Rupture of the Nanosized Metal Filament inside Oxide Matrix,"The paper presents a model of the electrically actuated formation and rupture
+of the nanosized metal filament inside oxide matrix. NiO oxide is used as an
+example for this model of ReRAM operation.",1102.3840v1
+2011-05-29,General considerations of the electrostatic boundary conditions in oxide heterostructures,"This is a book chapter that covers general considerations of the
+electrostatic stability of oxide surfaces and interfaces.",1105.5779v1
+2013-10-15,The chemical state of complex uranium oxides,"We report here the first direct observation of U(V) in uranium binary oxides
+and analyze the gradual conversion of the U oxidation state in the mixed
+uranium systems. Our finding clarifies previous contradicting results and
+provides important input for the geological disposal of spent fuel, recycling
+applications and chemistry of uranium species.",1310.4003v1
+2012-06-07,Resistive and magnetoresistive properties of CrO2 pressed powders with different types of inter-granular dielectric layers,"Resistive, magnetoresistive and magnetic properties of four kinds of pressed
+CrO2 powders, synthesized by hydrothermal method of chromic anhydride have been
+investigated. The particles in powders constituted of rounded particles
+(diameter 120 nm) or needle-shaped crystals with an average diameter of 22.9 nm
+and average length of 302 nm. All of the particles had a surface dielectric
+shell of varying thickness and different types (such as oxyhydroxide -CrOOH or
+chromium oxide Cr2O3). For all the samples at low temperatures we found
+non-metallic temperature dependence of resistivity and giant negative
+magnetoresistance (MR). The maximum value of MR at low temperatures (T \approx
+5 K) is \approx 37% in relatively small fields (0.5 T). At higher temperatures
+there was a rapid decrease of MR (up to \approx 1% / T at T \approx 200 K). The
+main objective of this work was studying the influence of properties and
+thickness of the intergranular dielectric layers, as well as CrO2 particle
+shape, on the magnitude of the tunneling resistance and MR of the pressed
+powder. The new results obtained in this study include: (1) detection at low
+temperatures in powders with needle-like particles a new type of MR hysteresis,
+and nonmonotonic MR behaviour with increasing magnetic field (absolute value of
+the MR at first grows rather rapidly with the field, and then begins
+diminishing markedly, forming a maximum), and (2) detection of non-monotonic
+temperature dependence, where - a field in which the resistance in a magnetic
+field has a maximum, as well as finding discrepancies in values of and
+coercivity fields, (3) detection of the anisotropy of MR, depending on the
+relative orientation of the transport current and the magnetic field, (4) a new
+method of synthesis, to regulate the thickness of dielectric coating.",1206.1533v1
+2014-02-13,A new spin-anisotropic harmonic honeycomb iridate,"The physics of Mott insulators underlies diverse phenomena ranging from high
+temperature superconductivity to exotic magnetism. Although both the electron
+spin and the structure of the local orbitals play a key role in this physics,
+in most systems these are connected only indirectly --- via the Pauli exclusion
+principle and the Coulomb interaction. Iridium-based oxides (iridates) open a
+further dimension to this problem by introducing strong spin-orbit
+interactions, such that the Mott physics has a strong orbital character. In the
+layered honeycomb iridates this is thought to generate highly spin-anisotropic
+interactions, coupling the spin orientation to a given spatial direction of
+exchange and leading to strongly frustrated magnetism. The potential for new
+physics emerging from such interactions has driven much scientific excitement,
+most recently in the search for a new quantum spin liquid, first discussed by
+Kitaev \cite{kitaev_anyons_2006}. Here we report a new iridate structure that
+has the same local connectivity as the layered honeycomb, but in a
+three-dimensional framework. The temperature dependence of the magnetic
+susceptibility exhibits a striking reordering of the magnetic anisotropy,
+giving evidence for highly spin-anisotropic exchange interactions. Furthermore,
+the basic structural units of this material suggest the possibility of a new
+family of structures, the `harmonic honeycomb' iridates. This compound thus
+provides a unique and exciting glimpse into the physics of a new class of
+strongly spin-orbit coupled Mott insulators.",1402.3254v2
+2014-04-08,What constitutes a nanoswitch? A Perspective,"Progress in the last two decades has effectively integrated spintronics and
+nanomagnetics into a single field, creating a new class of spin-based devices
+that are now being used both to Read (R) information from magnets and to Write
+(W) information onto magnets. Many other new phenomena are being investigated
+for nano-electronic memory as described in Part II of this book. It seems
+natural to ask whether these advances in memory devices could also translate
+into a new class of logic devices.
+  What makes logic devices different from memory is the need for one device to
+drive another and this calls for gain, directionality and input-output
+isolation as exemplified by the transistor. With this in mind we will try to
+present our perspective on how W and R devices in general, spintronic or
+otherwise, could be integrated into transistor-like switches that can be
+interconnected to build complex circuits without external amplifiers or clocks.
+We will argue that the most common switch used to implement digital logic based
+on complementary metal oxide semiconductor (CMOS) transistors can be viewed as
+an integrated W-R unit having an input-output asymmetry that give it gain and
+directionality. Such a viewpoint is not intended to provide any insight into
+the operation of CMOS switches, but rather as an aid to understanding how W and
+R units based on spins and magnets can be combined to build transistor-like
+switches. Next we will discuss the standard W and R units used for magnetic
+memory devices and present one way to integrate them into a single unit with
+the input electrically isolated from the output. But we argue that this
+integrated W-R unit would not provide the key property of gain. We will then
+show that the recently discovered giant spin Hall effect could be used to
+construct a W-R unit with gain and suggest other possibilities for spin
+switches with gain.",1404.2254v1
+2014-09-29,Magnetotransport Measurements of the Surface States of Samarium Hexaboride using Corbino Structures,"The recent conjecture of a topologically-protected surface state in SmB$_6$
+and the verification of robust surface conduction below 4 K have prompted a
+large effort to understand the surface states. Conventional Hall transport
+measurements allow current to flow on all surfaces of a topological insulator,
+so such measurements are influenced by contributions from multiple surfaces of
+varying transport character. Instead, we study magnetotransport of SmB$_6$
+using a Corbino geometry, which can directly measure the conductivity of a
+single, independent surface. Both (011) and (001) crystal surfaces show a
+strong negative magnetoresistance at all magnetic field angles measured. The
+(011) surface has a carrier mobility of $122\text{
+cm}^2/\text{V}\cdot\text{sec}$ with a carrier density of $2.5\times10^{13}
+\text{ cm}^{-2}$, which are significantly smaller than indicated by Hall
+transport studies. This mobility value can explain a failure so far to observe
+Shubnikov-de Haas oscillations. Analysis of the angle-dependence of
+conductivity on the (011) surface suggests a combination of a field-dependent
+enhancement of the carrier density and a suppression of Kondo scattering from
+native oxide layer magnetic moments as the likely origin of the negative
+magnetoresistance. Our results also reveal a hysteretic behavior whose
+magnitude depends on the magnetic field sweep rate and temperature. Although
+this feature becomes smaller when the field sweep is slower, does not disappear
+or saturate during our slowest sweep-rate measurements, which is much slower
+than a typical magnetotransport trace. These observations cannot be explained
+by quantum interference corrections such as weak anti-localization, but are
+more likely due to an extrinsic magnetic effect such as the magnetocaloric
+effect or glassy ordering.",1409.8199v2
+2016-09-02,Semiclassical theory of anisotropic transport at LaAlO3/SrTiO3 interfaces under in-plane magnetic field,"The unconventional magnetotransport at the interface between transition-metal
+oxides $LaAlO_3$ (LAO) and $SrTiO_3$ (STO) is frequently related to mobile
+electrons interacting with localized magnetic moments. However nature and
+properties of magnetism at this interface are not well understood so far. In
+this paper, we focus on transport effects driven by spin-orbit coupling and
+intentionally neglect possible strong correlations. The electrical resistivity
+tensor is calculated as a function of the magnitude and orientation of an
+external magnetic field parallel to the interface. The semiclassical Boltzmann
+equation is solved numerically for the two-dimensional system of spin-orbit
+coupled electrons accelerated by an electric field and scattered by
+spatially-correlated impurities. At temperatures of a few Kelvin and densities
+such that the chemical potential crosses the second pair of spin-orbit split
+bands, we find a strongly anisotropic modulation of the (negative)
+magnetoresistance above 10 T, characterized by multiple maxima and minima away
+from the crystalline axes. Along with the drop of the magnetoresistance, an
+abrupt enhancement of the transverse resistivity occurs. The angular modulation
+of the latter considerably deviates from a (low-field) sinusoidal dependence to
+a (high-field) step-like behaviour. These peculiar features are the
+consequences of the anisotropy of both (intra-band and inter-band )
+scattering-amplitudes in the Brillouin zone when the relevant energy scales in
+the system - chemical potential, spin-orbit interaction and Zeeman energy - are
+all comparable to each other. The theory provides good qualitative agreement
+with experimental data in the literature.",1609.00663v3
+2018-11-01,Ordered magnetism in the intrinsically decorated $j\rm{_{eff}}$ = $\frac{1}{2}$ $α$-CoV$_{3}$O$_{8}$,"The antiferromagnetic mixed valence ternary oxide $\alpha$-CoV$_{3}$O$_{8}$
+displays disorder on the Co$^{2+}$ site that is inherent to the $Ibam$ space
+group. The zero field structural and dynamic properties of
+$\alpha$-CoV$_{3}$O$_{8}$~have been investigated using a combination of neutron
+and x-ray diffraction, DC susceptibility, and neutron spectroscopy. The low
+temperature magnetic and structural properties are consistent with a random
+macroscopic distribution of Co$^{2+}$ over the 16$k$ metal sites. However, by
+applying the sum rules of neutron scattering we observe the collective magnetic
+excitations are parameterized with an ordered Co$^{2+}$ arrangement and
+critical scattering consistent with a three dimensional Ising universality
+class. The low energy spectrum is well-described by Co$^{2+}$ cations coupled
+$via$ a three dimensional network composed of competing ferromagnetic and
+stronger antiferromagnetic superexchange within the $ab$ plane and along $c$,
+respectively. While the extrapolated Weiss temperature is near zero, the 3D
+dimensionality results in long range antiferromagnetic order at
+$T\rm{_{N}}\sim$ 19 K. A crystal field analysis finds two bands of excitations
+separated in energy at $\hbar \omega$ $\sim$ 5 meV and 25 meV, consistent with
+a $j\rm{_{eff}}=\frac{1}{2}$ ground state with little mixing between spin-orbit
+split Kramers doublets. A comparison of our results to the random 3D Ising
+magnets and other compounds where spin-orbit coupling is present indicate that
+the presence of an orbital degree of freedom, in combination with strong
+crystal field effects and well-separated $j\rm{_{eff}}$ manifolds may play a
+key role in making the dynamics largely insensitive to disorder.",1811.00395v2
+2014-03-11,Emergent quantum phases in a frustrated J1-J2 Heisenberg model on hyperhoneycomb lattice,"We investigate possible quantum ground states as well as the classical limit
+of a frustrated J1-J2 Heisenberg model on the three-dimensional (3D)
+hyperhoneycomb lattice. Our study is inspired by the recent discovery of
+beta-Li2IrO3, where Ir^{4+} ions form a 3D network with each lattice site being
+connected to three nearest neighbors. We focus on the influence of magnetic
+frustration caused by the second-nearest neighbor spin interactions. Such
+interactions are likely to be significant due to large extent of 5d orbitals in
+iridates or other 5d transition metal oxides. In the classical limit, the
+ground state manifold is given by line degeneracies of the spiral
+magnetic-order wavevectors when J2/J1\gtrsim 0.17 while the collinear stripy
+order is included in the degenerate manifold when J2/J1 = 0.5. Quantum
+order-by-disorder effects are studied using both the semi-classical $1/S$
+expansion in the spin wave theory and Schwinger boson approach. In general,
+certain coplanar spiral orders are chosen from the classical degenerate
+manifold for a large fraction of the phase diagram. Nonetheless quantum
+fluctuations favor the collinear stripy order over the spiral orders in an
+extended parameter region around J2/J1 = 0.5, despite the spin-rotation
+invariance of the underlying Hamiltonian. This is in contrast to the emergence
+of stripy order in the Heisenberg-Kitaev model studied earlier on the same
+lattice, where the Kitaev-type Ising interactions are important for stabilizing
+the stripy order. As quantum fluctuations become stronger, U(1) and Z2 quantum
+spin liquid phases are shown to arise via quantum disordering of the Neel,
+stripy and spiral magnetically-ordered phases. The effects of magnetic
+anisotropy and their relevance to future experiments are also discussed.",1403.2724v1
+2016-11-14,Impact of strain and morphology on magnetic properties of Fe$_3$O$_4$/NiO bilayers grown on Nb:SrTiO$_3$(001) and MgO(001),"We present a comparative study on the morphology and structural as well as
+magnetic properties of crystalline Fe$_3$O$_4$/NiO bilayers grown on both
+MgO(001) and SrTiO$_3$(001) substrates by reactive molecular beam epitaxy.
+These structures are investigated by means of x-ray photoelectron spectroscopy,
+low energy electron diffraction, x-ray reflectivity and diffraction as well as
+vibrating sample magnetometry. While the lattice mismatch of NiO grown on
+MgO(001) is only 0.8%, it is exposed to a lateral lattice mismatch of -6.9% if
+grown on SrTiO$_3$. In the case of Fe$_3$O$_4$, the misfit strain on MgO(001)
+and SrTiO$_3$(001) amounts to 0.3% and -7.5%, respectively. To clarify the
+relaxation process of the bilayer system, the film thicknesses of the magnetite
+and nickel oxide films have been varied between 5 and 20nm. While NiO films are
+well ordered on both substrates, Fe$_3$O$_4$ films grown on NiO/SrTiO$_3$
+exhibit a higher surface roughness as well as lower structural ordering
+compared to films grown on NiO/MgO. Further, NiO films grow pseudomorphic in
+the investigated thickness range on MgO substrates without any indication of
+relaxation, whereas on SrTiO$_3$ the NiO films show strong strain relaxation.
+Fe$_3$O$_4$ films exhibit also strong relaxation even for films of 5nm
+thickness on both NiO/MgO as well as on NiO/SrTiO$_3$. The magnetite layers on
+both substrates show a fourfold magnetic in-plane anisotropy with magnetic easy
+axes pointing in $\left\langle100\right\rangle$ directions. The coercive field
+is strongly enhanced for magnetite grown on NiO/SrTiO$_3$ due to higher density
+of structural defects, compared to magnetite grown on NiO/MgO.",1611.04402v2
+2008-07-09,Effects of Strain on Orbital Ordering and Magnetism at the Perovskite Oxide Interfaces: LaMnO$_3$/SrMnO$_3$,"We study how strain affects orbital ordering and magnetism at the interface
+between SrMnO$_3$ and LaMnO$_3$ from density-functional calculations and
+interpret the basic results in terms of a three-site Mn-O-Mn model. Magnetic
+interaction between the Mn atoms is governed by a competition between the
+antiferromagnetic superexchange of the Mn t$_{2g}$ core spins and the
+ferromagnetic double exchange of the itinerant e$_g$ electrons. While the core
+electrons are relatively unaffected by the strain, the orbital character of the
+itinerant electron is strongly affected, which in turn causes a large change in
+the strength of the ferromagnetic double exchange. The epitaxial strain
+produces the tetragonal distortion of the MnO$_6$ octahedron, splitting the
+Mn-e$_g$ states into x$^2$-y$^2$ and 3z$^2$-1 states, with the former being
+lower in energy, if the strain is tensile in the plane, and opposite if the
+strain is compressive. For the case of the tensile strain, the resulting higher
+occupancy of the x$^2$-y$^2$ orbital enhances the in-plane ferromagnetic double
+exchange owing to the larger electron hopping in the plane, causing at the same
+time a reduction of the out-of-plane double exchange. This reduction is large
+enough to be overcome by antiferromagnetic superexchange, which wins to produce
+a net antiferromagnetic interaction between the out-of-plane Mn atoms. For the
+case of the in-plane compressive strain, the reverse happens, viz., that the
+higher occupancy of the 3z$^2$-1 orbital results in the out-of-plane
+ferromagnetic interaction, while the in-plane magnetic interaction remains
+antiferromagnetic. Concrete density-functional results are presented for the
+(LaMnO$_3$)$_1$/(SrMnO$_3$)$_1$ and (LaMnO$_3$)$_1$/(SrMnO$_3$)$_3$
+superlattices for various strain conditions.",0807.1479v1
+2017-06-19,A Large-Diameter Hollow-Shaft Cryogenic Motor Based on a Superconducting Magnetic Bearing for Millimeter-Wave Polarimetry,"In this paper we present the design and measured performance of a novel
+cryogenic motor based on a superconducting magnetic bearing (SMB). The motor is
+tailored for use in millimeter-wave half-wave plate (HWP) polarimeters, where a
+HWP is rapidly rotated in front of a polarization analyzer or
+polarization-sensitive detector. This polarimetry technique is commonly used in
+cosmic microwave background (CMB) polarization studies. The SMB we use is
+composed of fourteen yttrium barium copper oxide (YBCO) disks and a contiguous
+neodymium iron boron (NdFeB) ring magnet. The motor is a hollow-shaft motor
+because the HWP is ultimately installed in the rotor. The motor presented here
+has a 100 mm diameter rotor aperture. However, the design can be scaled up to
+rotor aperture diameters of approximately 500 mm. Our motor system is composed
+of four primary subsystems: (i) the rotor assembly, which includes the NdFeB
+ring magnet, (ii) the stator assembly, which includes the YBCO disks, (iii) an
+incremental encoder, and (iv) the drive electronics. While the YBCO is cooling
+through its superconducting transition, the rotor is held above the stator by a
+novel hold and release mechanism (HRM). The encoder subsystem consists of a
+custom-built encoder disk read out by two fiber optic readout sensors. For the
+demonstration described in this paper, we ran the motor at 50 K and tested
+rotation frequencies up to approximately 10 Hz. The feedback system was able to
+stabilize the the rotation speed to approximately 0.4%, and the measured rotor
+orientation angle uncertainty is less than 0.15 deg. Lower temperature
+operation will require additional development activities, which we will
+discuss.",1706.05963v3
+2020-12-08,Large magneto-optical effect and magnetic anisotropy energy in two-dimensional metallic ferromagnet Fe$_3$GeTe$_2$,"Few layers Fe$_3$GeTe$_2$ is currently the only atomically thin ferromagnetic
+metal, and thus has drawn huge attention in the field of two-dimensional (2D)
+magnetism. In this paper, we perform a systematic first principle study on the
+electronic structure, magnetic anisotropy energy (MAE), and magneto-optical
+(MO) effects in monolayer (ML), bilayer (BL) and trilayer (TL) as well as bulk
+Fe$_3$GeTe$_2$. All the considered structures of Fe$_3$GeTe$_2$ are predicted
+to have large MAE of order $\sim$3.0 meV/f.u., being larger than reported 2D
+ferromagnetic semiconductors Cr$_2$Ge$_2$Te$_6$ and CrI$_3$ and also being
+comparable to that of FePt which has the largest MAE among the transition metal
+alloys. This large MAE thus stabilizes the long range ferromagnetic order down
+to atomically thin layers and also suggests promising applications of 2D
+Fe$_3$GeTe$_2$ in high density data storage. Furthermore, the calculated
+magneto-optical spectra show large magnetic circular dichroism, thus resulting
+in large MO Kerr rotation and Faraday rotation angles. In visible frequency
+range, Kerr rotation angles up to $\sim$1.0$^\circ$ for TL Fe$_3$GeTe$_2$ are
+found. Such values are larger than famous MO transition metal alloy MnBi. Also,
+large Faraday rotation angles are predicted for all considered Fe$_3$GeTe$_2$
+structures. In particular, ML Fe$_3$GeTe$_2$ has a Faraday rotation angle of
+-156$^\circ$/$\mu m$, which is three times larger than famous MO oxide
+Bi$_3$Fe$_5$O$_{12}$. These important findings are analysed in terms of the
+calculated orbital-decomposed density of states and dipole selection rule
+derived from the group theory. Our findings thus suggest that few layers and
+bulk Fe$_3$GeTe$_2$ are promising MO materials and could be widely applied to
+nano MO devices in the future.",2012.04285v2
+2018-12-20,Single-spin qubits in isotopically enriched silicon at low magnetic field,"Single-electron spin qubits employ magnetic fields on the order of 1 Tesla or
+above to enable quantum state readout via spin-dependent-tunnelling. This
+requires demanding microwave engineering for coherent spin resonance control
+and significant on-chip real estate for electron reservoirs, both of which
+limit the prospects for large scale multi-qubit systems. Alternatively,
+singlet-triplet (ST) readout enables high-fidelity spin-state measurements in
+much lower magnetic fields, without the need for reservoirs. Here, we
+demonstrate low-field operation of metal-oxide-silicon (MOS) quantum dot qubits
+by combining coherent single-spin control with high-fidelity, single-shot,
+Pauli-spin-blockade-based ST readout. We discover that the qubits decohere
+faster at low magnetic fields with $T_{2}^{Rabi}=18.6$~$\mu$s and
+$T_2^*=1.4$~$\mu$s at 150~mT. Their coherence is limited by spin flips of
+residual $^{29}$Si nuclei in the isotopically enriched $^{28}$Si host material,
+which occur more frequently at lower fields. Our finding indicates that new
+trade-offs will be required to ensure the frequency stabilization of spin
+qubits and highlights the importance of isotopic enrichment of device
+substrates for the realization of a scalable silicon-based quantum processor.",1812.08347v5
+2020-06-23,Electron doping of the layered nickelate La$_4$Ni$_3$O$_{10}$ by aluminum substitution: A combined experimental and DFT study,"The physical properties of La$_4$Ni$_3$O$_{10}$ with a 2D-like
+Ruddlesden-Popper-type crystal structure are extraordinarily dependent on
+temperature and chemical substitution. By introducing Al$^{3+}$ atoms ($x$)
+randomly at the Ni-sites, the average oxidation state for the two
+non-equivalent Ni-cations is tuned and adopt values below the average of +2.67
+in La$_4$Ni$_3$O$_{10}$. La$_4$Ni$_{3-x}$Al$_x$O$_{10}$ is a solid solution for
+$x=0.00$ to 1.00, and are prepared by the citric acid method. The samples adopt
+a slightly distorted monoclinic structure (P21/a), evidenced by peak broadening
+of the (117) reflection. We report on a remarkable effect on the electronic
+properties induced by tiny amounts of homogeneously distributed Al-cations,
+with clear correspondence between resistivity, magnetization, diffraction, and
+DFT data. DFT shows that electronically there is no significant difference
+between the non-equivalent Ni atoms and no tendency towards any
+Ni$^{3+}$/Ni$^{2+}$ charge ordering. The electron doping via Al-substitution
+has a profound effect on electric and magnetic properties. The resistivity
+changes from metallic to semiconducting with increasing band-gap at higher
+Al-levels, consistent with results from DFT. The metal-to-metal transition
+reported for La$_4$Ni$_3$O$_{10}$, which is often interpreted as a charge
+density wave, is maintained until $x = 0.15$ Al-level. However, the temperature
+characteristics of the resistivity change already at very low Al-levels (below
+0.03). A coupling of the metal-to-metal transition to the lattice is evidenced
+by an anomaly in the unit cell dimensions. No long-range magnetic order is
+detected by powder neutron diffraction. The introduction of the non-magnetic
+Al$^{3+}$ changes the Ni$^{3+}$/Ni$^{2+}$ ratio and is likely to block
+double-exchange pathways by means of -Ni-O-Al-O-Ni- fragments into the network
+of corner shared octahedra with the emergence of possible short-range order in
+ferromagnetic like islands.",2006.12854v1
+2021-04-23,Roadmap of spin-orbit torques,"Spin-orbit torque (SOT) is an emerging technology that enables the efficient
+manipulation of spintronic devices. The initial processes of interest in SOTs
+involved electric fields, spin-orbit coupling, conduction electron spins and
+magnetization. More recently interest has grown to include a variety of other
+processes that include phonons, magnons, or heat. Over the past decade, many
+materials have been explored to achieve a larger SOT efficiency. Recently,
+holistic design to maximize the performance of SOT devices has extended
+material research from a nonmagnetic layer to a magnetic layer. The rapid
+development of SOT has spurred a variety of SOT-based applications. In this
+Roadmap paper, we first review the theories of SOTs by introducing the various
+mechanisms thought to generate or control SOTs, such as the spin Hall effect,
+the Rashba-Edelstein effect, the orbital Hall effect, thermal gradients,
+magnons, and strain effects. Then, we discuss the materials that enable these
+effects, including metals, metallic alloys, topological insulators,
+two-dimensional materials, and complex oxides. We also discuss the important
+roles in SOT devices of different types of magnetic layers. Afterward, we
+discuss device applications utilizing SOTs. We discuss and compare
+three-terminal and two-terminal SOT-magnetoresistive random-access memories
+(MRAMs); we mention various schemes to eliminate the need for an external
+field. We provide technological application considerations for SOT-MRAM and
+give perspectives on SOT-based neuromorphic devices and circuits. In addition
+to SOT-MRAM, we present SOT-based spintronic terahertz generators,
+nano-oscillators, and domain wall and skyrmion racetrack memories. This paper
+aims to achieve a comprehensive review of SOT theory, materials, and
+applications, guiding future SOT development in both the academic and
+industrial sectors.",2104.11459v2
+2023-03-03,Comparative study of magnetocaloric properties for Gd$^{3+}$ compounds with different frustrated lattice geometries,"As materials with suppressed ordering temperatures and enhanced ground state
+entropies, frustrated magnetic oxides are ideal candidates for cryogenic
+magnetocaloric refrigeration. While previous materials design has focused on
+tuning the magnetic moments, their interactions, and density of moments on the
+lattice, there has been relatively little attention to frustrated lattices.
+Prior theoretical work has shown that the magnetocaloric cooling rate at the
+saturation field is proportional to a macroscopic number of soft mode
+excitations that arise due to the classical ground state degeneracy. The number
+of these modes is directly determined by the geometry of the frustrating
+lattice. For corner-sharing geometries, the pyrochlore has 50\% more modes than
+the garnet and kagome lattices, whereas the edge-sharing \emph{fcc} has only a
+subextensive number of soft modes. Here, we study the role of soft modes in the
+magnetocaloric effect of four large-spin Gd$^{3+}$ ($L=0$, $J=S=7/2$)
+Heisenberg antiferromagnets on a kagome, garnet, pyrochlore, and \emph{fcc}
+lattice. By comparing measurements of the magnetic entropy change $\Delta S_m$
+of these materials at fields up to $9$~T with predictions using mean-field
+theory and Monte Carlo simulations, we are able to understand the relative
+importance of spin correlations and quantization effects. We observe that
+tuning the value of the nearest neighbor coupling has a more dominant
+contribution to the magnetocaloric entropy change in the liquid-He cooling
+regime ($2$-$20$~K), rather than tuning the number of soft mode excitations.
+Our results inform future materials design in terms of dimensionality, degree
+of magnetic frustration, and lattice geometry.",2303.01773v1
+2023-08-22,"Structural, morphological, and magnetic characterizations of (Fe0.25Mn0.75)2O3 nanocrystals: a comprehensive stoichiometric determination","Iron manganese trioxide (Fe0.25Mn0.75)2O3 nanocrystals were synthesized by
+the sol-gel method. The 80 K Mossbauer spectrum was well-fitted using two
+doublets representing the 8b and 24d crystallographic sites of the
+(FexMn1-x)2O3 phase and two weak extra sextets which were attributed to
+crystalline and amorphous hematite. Our findings showed formation of a bixbyite
+primary phase. The Raman spectrum exhibits six Raman active modes, typical of
+(Fe,Mn)2O3, and two extra Raman modes associated with the secondary hematite
+phase. X-ray photoelectron spectroscopy analysis confirmed the presence of
+oxygen vacancy onto the (FexMn1-x)2O3 particle surface, with varying oxidation
+states. X-band magnetic resonance data revealed a single broad resonance line
+in the whole temperature range (3.8 K - 300 K). The temperature dependence of
+both resonance field and resonance linewidth shows a remarkable change in the
+range of 40 - 50 K, herein credited to surface spin glass behavior. The model
+picture used assumes (FexMn1-x)2O3 nanoparticles with a core-shell structure.
+Results indicate that below about 50 K the spin system of shell reveals a
+paramagnetic to spin glass-like transition upon cooling, with a critical
+temperature estimated at 43 K. In the higher temperature range, the
+superparamagnetic hematite (secondary) phase contributes remarkably to the
+temperature dependence of the resonance linewidth. Zero-field-cooled (ZFC) and
+fieldcooled (FC) data show strong irreversibility and a peak in the ZFC curve
+at 33 K, attributed to a paramagnetic-ferrimagnetic transition of the main
+phase. Hysteresis curve at 5 K shows a low coercive field of 4 kOe, with the
+magnetization not reaching saturation at 70 kOe, suggesting the occurrence of a
+ferrimagnetic core with a magnetic disorder at surface, characteristic of
+core-shell spin-glass-like behavior.",2308.11128v2
+2002-08-07,First-principles theoretical evaluation of crystalline zirconia and hafnia as gate oxides for Si microelectronics,"Parameters determining the performance of the crystalline oxides zirconia
+(ZrO_2) and hafnia (HfO_2) as gate insulators in nanometric Si electronics are
+estimated via ab initio calculations of the energetics, dielectric properties,
+and band alignment of bulk and thin-film oxides on Si (001). With their large
+dielectric constants, stable and low-formation-energy interfaces, large valence
+offsets, and reasonable (though not optimal) conduction offsets (electron
+injection barriers), zirconia and hafnia appear to have a considerable
+potential as gate oxides for Si electronics.",0208149v1
+2003-01-07,Transient-Enhanced Surface Diffusion on Native-Oxide-Covered Si(001) Nano-Structures during Vacuum Annealing,"We report on the transient-enhanced shape transformation of nano-structured
+Si(001) surfaces upon in vacuo annealing at relatively low temperatures of
+1175K - 1225K for a few minutes. We find dramatic surface mass transport
+concomitant with the development of low-energy facets on surfaces that are
+covered by native oxide. The enhanced surface mass transport ceases after the
+oxide is completely desorbed, and it is also not observed on surfaces where the
+native oxide had been removed by HF before annealing.",0301074v1
+2005-04-11,Ab-initio simulations on growth and interface properties of epitaxial oxides on silicon,"The replacement of SiO2 by so-called high-k oxides is one of the major
+challenges for the semiconductor industry to date. Based on electronic
+structure calculations and ab-initio molecular dynamics simulations, we are
+able to provide a consistent picture of the growth process of a class of
+epitaxial oxides around SrO and SrTiO3. The detailed understanding of the
+interfacial binding principles has also allowed us to propose a way to engineer
+the band-offsets between the oxide and the silicon substrate.",0504256v1
+2008-04-04,Modeling of graphite oxide,"Based on density functional calculations, optimized structures of graphite
+oxide are found for various coverage by oxygen and hydroxyl groups, as well as
+their ratio corresponding to the minimum of total energy. The model proposed
+describes well known experimental results. In particular, it explains why it is
+so difficult to reduce the graphite oxide up to pure graphene. Evolution of the
+electronic structure of graphite oxide with the coverage change is
+investigated.",0804.0784v2
+2010-09-06,Graphene produced by radiation-induced reduction of graphene oxide,"Effect of irradiation on graphene oxide by sunlight, UV light and KrF excimer
+laser has been investigated in detail. Both sunlight and ultraviolet light
+reduce graphene oxide well after prolonged irradiation, but laser irradiation
+produces graphene with negligible oxygen functionalities within a short time.
+Laser irradiation is also useful for one-step synthesis of metal particle
+decorated graphene. Laser irradiation of graphene oxide appears to be an
+efficient procedure for large-scale synthesis of graphene.",1009.1028v2
+2011-07-13,High-temperature oxide thermoelectrics,"We have evaluated the power factor of transition metal oxides at high
+temperatures using the Heikes formula and the Ioffe-Regel conductivity. The
+evaluated power factor is found to be nearly independent of carrier
+concentration in a wide range of doping, and well explains the experimental
+data for cobalt oxides. This suggests that the same power factor can be
+obtained with a thermopower larger than $2k_B/e$, and also suggests a
+reasonably high value of the dimensionless figure of merit $ZT$. We propose an
+oxide thermoelectric power generator by using materials having a thermopower
+larger than 300 $\mu$V/K.",1107.2530v1
+2012-12-03,Formation enthalpy of BaCe0.7Nd0.2In0.1O2.85,"In this paper for the first time we synthesized the compound
+BaCe0.7Nd0.2In0.1O2.85 by solid-state reaction. The phase has orthorhombic
+structure (space group Pmcn). We also measured the standard formation
+enthalpies of BaCe0.7Nd0.2In0.1O2.85 by solution calorimetry in 1 M HCl with
+0.1 M KI. We determined the stability of Nd(In)-doped barium cerate with
+respect to mixtures of binary oxides. On the basis of these data we established
+that above-mentioned mixed oxide is thermodynamically stable with respect to
+their decomposition into binary oxides at room temperatures. We also
+established that BaCe0.7Nd0.2In0.1O2.85 oxide is thermodynamically favoured
+than BaCe0.8Nd0.2O2.9.",1212.0344v1
+2013-01-15,Massive production of graphene oxide from expanded graphite,"In a deviation from the conventional Hummers method, a spontaneous expansion
+approach was introduced with expanded graphite as the precursors. The
+intercalating agent (H2SO4) was able to penetrate into the expanded graphite;
+this had further expanded the graphite and as a result, a foam-like
+intermediate was produced. The foam-like graphite was more easily oxidized in
+reaction with the oxidant (KMnO4) to form graphene oxide (GO). Fully exfoliated
+GO was obtained with expanded graphite having the median diameter ~ 15 {\mu}m
+as the precursors. This procedure was much safer and productive in scalable
+applications than the conventional Hummers methods.",1301.3253v1
+2013-03-18,Exploring Morphology-Activity Relationships: Ab Initio Wulff Construction for RuO2 Nanoparticles under Oxidizing Conditions,"We present a density-functional theory based Wulff construction of the
+equilibrium shape of RuO2 particles in an oxygen environment. The obtained
+intricate variations of the crystal habit with the oxygen chemical potential
+allow for a detailed discussion of the dependence on the oxidizing pretreatment
+observed in recent powder catalyst studies. The analysis specifically indicates
+an incomplete particle shape equilibration in previously employed low
+temperature calcination. Equilibrated particles could be active CO oxidation
+catalysts with long-term stability in oxidizing feed and then represent an
+interesting alternative to the previously suggested core-shell concept.",1303.4203v1
+2013-05-24,Interatomic potential for the calculation of barrier distributions in amorphous oxides,"Amorphous oxides are important for implants, optics, and gate insulators.
+Understanding the effects of oxide doping is crucial to optimize performance.
+Here we report energy barrier distributions for amorphous tantala and doped
+oxides using a new set of computationally efficient, two-body potentials that
+reproduce the structural properties of the samples. The distributions can be
+directly compared to experiment and used to calculate physical quantities such
+as internal friction.",1305.5821v1
+2013-07-30,Synthesis of Self-assembled Iron Silicon Oxide Nanowires onto Single-crystalline Si(100),"Iron silicon oxide nanowire has been synthesized by putting single
+crystalline Si(100) wafer into ammonium iron sulfate, hydrogen peroxide, and
+triethylamine solution heated to from 70 to 100 degree in the air. The prepared
+iron silicon oxide nanowires with diameters of about 10nm (onto non etched
+Si(100) wafer) and about 75nm(onto etched Si(100) wafer) and their self
+assembles were characterized. The possible mechanism that accounted for the
+formation of iron silicon oxide nanowire is suggested based on experimental
+evidence.",1307.7783v1
+2015-02-11,Excited States at Interfaces of a Metal-Supported Ultrathin Oxide Film,"We report layer-resolved measurements of the \textit{unoccupied} electronic
+structure of ultrathin MgO films grown on Ag(001). The metal-induced gap states
+at the metal/oxide interface, the oxide band gap as well as a surface core
+exciton involving an image-potential state of the vacuum are revealed through
+resonant Auger spectroscopy of the Mg $KL_{23}L_{23}$ Auger transition. Our
+results demonstrate how to obtain new insights on \textit{empty} states at
+interfaces of metal-supported ultrathin oxide films.",1502.03227v3
+2016-03-07,Flexible Metal Oxide/Graphene Oxide Hybrid Neuromorphic Devices on Flexible Conducting Graphene Substrates,"Flexible metal oxide/graphene oxide hybrid multi-gate neuron transistors were
+fabricated on flexible graphene substrates. Dendritic integrations in both
+spatial and temporal modes were successfully emulated, and spatiotemporal
+correlated logics were obtained. A proof-of-principle visual system model for
+emulating lobula giant motion detector neuron was investigated. Our results are
+of great interest for flexible neuromorphic cognitive systems.",1609.00032v1
+2016-10-30,On Static Dielectric Response of Microcomposites of the Type Ferrolastics-Dielectrics For Application in Solid Oxide Fuel Cells (SOFC),"We describe the static dielectric response of ferroelastic-dielectric
+microcomposites. Dependence on temperature, pressure and concentration is
+considered for temperatures in the paraelastic transition. In recent years
+there has been considerable interest in perovskite oxides for application in
+solid oxide fuel cells (SOFC), exhaust gas sensors in automobiles, membranes
+for separation processes and as catalysts, which are of the ferroeleastic
+nature, f.e. of the ($ LaSrCoO_{3}$) type. Ferroelastic-dielectric
+microcomposites and measurement of their properties may improve properties of
+perovskite oxides for these applications.",1610.09617v1
+2020-07-29,Order-Disorder Behavior at Thin Film Oxide Interfaces,"Order-disorder processes fundamentally determine the structure and properties
+of many important oxide systems for energy and computing applications. While
+these processes have been intensively studied in bulk materials, they are less
+investigated and understood for nanostructured oxides in highly non-equilibrium
+conditions. These systems can now be realized through a range of deposition
+techniques and probed at exceptional spatial and chemical resolution, leading
+to a greater focus on interface dynamics. Here we survey a selection of recent
+studies of order-disorder behavior at thin film oxide interfaces, with a
+particular emphasis on the emergence of order during synthesis and disorder in
+extreme irradiation environments. We summarize key trends and identify
+directions for future study in this growing research area.",2007.15136v1
+2010-05-26,Substrate coherency-driven octahedral rotations in perovskite oxide films,"We perform first-principles density functional calculations to explore the
+role of substrate proximity effects on the octahedral rotation patterns in
+perovskite oxide superlattices. With cubic perovskite SrFeO$_3$ as our model
+film and tetragonal SrTiO$_3$ as the substrate, we show that in most cases the
+substrate octahedral rotation patterns propagate into the film across the
+heterointerface. We also identify elastic boundary conditions for which the
+enforced structural coherence induces atomic displacement patterns that are not
+found in the bulk phase diagram of either individual constituent. We suggest
+that such substrate coherency-induced octahedral texturing of thin film oxides
+is a promising approach for tuning the electronic structure of functional oxide
+thin films.",1005.4835v1
+2016-11-08,Reduced Graphene Oxide and Its Natural Counterpart Shungite Carbon,"Large variety of structure and chemical-composition of reduced graphene oxide
+(RGO) is explained from a quantum-chemical standpoint. The related molecular
+theory of graphene oxide, supported by large experience gained by the modern
+graphene science, has led the foundation of the concept of a multi-stage
+graphene oxide reduction. This microscopic approach has found a definite
+confirmation when analyzing the available empirical data concerning both
+synthetic and natural RGO products, the latter in view of shungite carbon,
+suggesting the atomic-microscopic model for its structure.",1611.02696v1
+2016-08-31,Spontaneous dehydrogenation of methanol over defect-free MgO(100) thin film deposited on molybdenum,"The dehydrogenation reaction of methanol on metal supported MgO(100) films
+has been studied by employing periodic density functional calculations. As far
+as we know, the dehydrogenation of single methanol molecule over inert oxide
+insulators such as MgO has never been realized before without the introduction
+of defects and low coordinated atoms. By depositing the very thin oxide films
+on Mo substrate we have successfully obtained the dissociative state of
+methanol. The dehydrogenation reaction is energetically exothermic and nearly
+barrierless. The metal supported thin oxide films studied here provide a
+versatile approach to enhance the activity and properties of oxides.",1608.08827v1
+2017-06-19,An efficient and reliable growth method for epitaxial complex oxide films by molecular beam epitaxy,"Transition metal oxide heterostructures and interfaces host a variety of
+exciting quantum phases and can be grown with atomic-scale precision by
+utilising the intensity oscillations of $in$ $situ$ reflection high-energy
+electron diffraction (RHEED). However, establishing a stable oscillation
+pattern in the growth calibration of complex oxides films is very challenging
+and time consuming. Here, we develop a substantially more efficient and
+reliable growth calibration method for complex oxide films using molecular beam
+epitaxy.",1706.05797v1
+2017-10-25,Ordered C vacancies in titanium carbides: a correlation between crystal structure and the effects on oxidation behavior at elevated temperature,"It has been widely accepted that the introduction of titanium carbides into
+titanium-based alloys can significantly enhance the oxidation resistance due to
+their superior physicochemical stability at elevated temperatures. The present
+study reported for the first time that the ordered C vacancies within titanium
+carbides could lead to an uncommon phenomenon particularly at the very initial
+stage of oxidation. The intrinsic micro-to-macro oxidation mechanisms were
+systematically clarified with the aids of transmission electron microscope and
+ab-initio molecular dynamics simulation.",1710.09311v1
+2018-10-24,On the effect of Ti on Oxidation Behaviour of a Polycrystalline Nickel-based Superalloy,"Titanium is commonly added to nickel superalloys but has a well-documented
+detrimental effect on oxidation resistance. The present work constitutes the
+first atomistic-scale quantitative measurements of grain boundary and bulk
+compositions in the oxide scale of a current generation polycrystalline nickel
+superalloy performed through atom probe tomography. Titanium was found to be
+particularly detrimental to oxide scale growth through grain boundary
+diffusion.",1810.10444v1
+2021-01-19,High temperature oxidation behavior of disordered (Ti0.5Zr0.5)2AlC MAX phase via a Machine Learning-Augmented DFT Approach,"The Zr-based MAX phases have attracted considerable attention for their
+outstanding irradiation behavior and high neutron transparency relevant to
+nuclear power generation technologies. In spite of increased understanding of
+physical behavior crystalline MAX phases, the high-temperature oxidation
+behavior and reaction mechanism of disordered MAX phases both from theory and
+experiments are not well understood due to increased system complexity. Here,
+we present a detailed comparative assessment of high-temperature
+thermodynamic-stability and oxidation behavior (reaction-products and chemical
+activity) of ordered Ti2AlC and disordered (Ti0.5Zr0.5)2AlC. We believe that
+the new insights will enhance our understanding of oxidation process in
+disordered MAX phases.",2101.07460v1
+2019-01-27,A simple INDIUM TIN OXIDE/glass DRA,"A novel Dielectric Resonator Antenna, simply made of INDIUM TIN OXIDE coated
+glass slides placed on a microstrip transmission line, for communication
+applications is presented. Changes in the bandwidth and gain of the antenna are
+observed by modifying the dimensions of the INDIUM TIN OXIDE coated glass
+slides. Changes in gain, directivity and reflection coefficient are observed. A
+parametric study is conducted on the size of the DRA to understand the effect
+on bandwidth, reflection coefficient and gain.",1901.09340v1
+2021-12-23,Metal Oxide Nanoparticles and Their Applications: A Report,"Herein, we report a brief introduction of metal oxide nanoparticles and their
+diverse applications in different scientific and medical fields. This report
+will be updated frequently to give a complete review in similar fields of
+nanotechnology. In the present version of the report, an introduction to
+nanotechnology and nanomaterials with some synthesis routes (such as
+Hydrothermal synthesis and Sol-Gel synthesis etc.) to prepare the metal oxide
+nanoparticles is given. In this version we have primarily included the basic
+introduction of application of metal oxide nanoparticles in the fields of
+biomedical, resistive switching and photovoltaic etc.",2201.04938v1
+2023-04-13,Probing magnetic ordering in air stable iron-rich van der Waals minerals,"In the rapidly expanding field of two-dimensional materials, magnetic
+monolayers show great promise for the future applications in nanoelectronics,
+data storage, and sensing. The research in intrinsically magnetic
+two-dimensional materials mainly focuses on synthetic iodide and telluride
+based compounds, which inherently suffer from the lack of ambient stability. So
+far, naturally occurring layered magnetic materials have been vastly
+overlooked. These minerals offer a unique opportunity to explore air-stable
+complex layered systems with high concentration of local moment bearing ions.
+We demonstrate magnetic ordering in iron-rich two-dimensional phyllosilicates,
+focusing on mineral species of minnesotaite, annite, and biotite. These are
+naturally occurring van der Waals magnetic materials which integrate local
+moment baring ions of iron via magnesium/aluminium substitution in their
+octahedral sites. Due to self-inherent capping by silicate/aluminate
+tetrahedral groups, ultra-thin layers are air-stable. Chemical
+characterization, quantitative elemental analysis, and iron oxidation states
+were determined via Raman spectroscopy, wavelength disperse X-ray spectroscopy,
+X-ray absorption spectroscopy, and X-ray photoelectron spectroscopy.
+Superconducting quantum interference device magnetometry measurements were
+performed to examine the magnetic ordering. These layered materials exhibit
+paramagnetic or superparamagnetic characteristics at room temperature. At low
+temperature ferrimagnetic or antiferromagnetic ordering occurs, with the
+critical ordering temperature of 38.7 K for minnesotaite, 36.1 K for annite,
+and 4.9 K for biotite. In-field magnetic force microscopy on iron bearing
+phyllosilicates confirmed the paramagnetic response at room temperature,
+present down to monolayers.",2304.06533v1
+2021-04-28,Graphene oxide doped ethanol droplet combustion: Ignition delay and contribution of atomization to burning rate,"Effects of graphene oxide nanomaterials addition and oxidation level on
+ignition delay and burning rate of ethanol droplets are experimentally
+investigated. Three graphene oxide samples are synthesized and characterized.
+Separate high-speed OH* chemiluminescence and high-speed shadowgraphy images
+are collected. The results suggest that increasing the loading concentration
+from 0 to 0.1% generally increases the ignition delay, except for ethanol doped
+with the highly oxidized graphene. The probability density function of the
+atomized baby droplet diameter, initial projected velocity, and length of the
+projected trajectory are similar for all tested conditions and independent of
+the oxidation level and loading concentration of the additives. The joint
+probability density function calculated for the atomization-related parameters
+against one another suggests that the majority of the baby droplets feature a
+relatively short lifetime, indicating they may potentially burn inside the
+flame envelope. Using droplet surface regression curves versus time, the
+burning rate for periods in which the atomization does not occur, and for the
+periods that the atomization is present are estimated. The former burning rate
+is shown to enhance by increasing the loading concentration and reducing the
+oxidation level of graphene. However, it is found that a maximum increase in
+the latter burning rate for both loading concentrations occurs for ethanol
+doped with the graphene oxide that features maximum amount of infrared
+radiation absorption. It is shown that relatively intense atomization
+suppresses the mass loss. Doping ethanol with graphene oxide and increasing the
+loading concentration from 0.01 to 0.1% enhances the overall burning rate, with
+a maximum enhancement of 8.4% pertaining to addition of reduced oxidized
+graphene oxide and for the loading concentration of 0.1%.",2104.13544v1
+2022-04-29,Modeling the Initial Stages of Si(100) Thermal Oxidation: An Ab-initio Approach,"Silicon together with its native oxide SiO$_2$ was recognized as an
+outstanding material system for the semiconductor industry in the 1950s. In
+state-of-the-art device technology, SiO$_2$ is widely used as an insulator in
+combination with high-$k$ dielectrics such as HfO$_2$, demanding fabrication of
+ultra-thin interfacial layers. The classical standard model derived by Deal and
+Grove accurately describes the oxidation of Si in a progressed stage, however,
+strongly underestimates growth rates for thin oxide layers. Recent studies
+report a variety of oxidation mechanisms during the growth of oxide films in
+the range of \SI{10}{\angstrom} with various details still under debate. This
+paper presents a first-principles based approach to theoretically assess the
+thermal oxidation process of the technologically relevant Si(100) surfaceduring
+this initial stage. Our investigations range from the chemisorption of single
+O$_2$ molecules onto the $p(2\times2)$ reconstructed Si surface to oxidized Si
+surface layers with a thickness of up to \SI{20}{\angstrom}. The initially
+observed enhanced growth rate is assigned to barrierless O$_2$ chemisorption
+events upon which the oxygen molecule dissociate. We present strong evidence
+for an immediate amorphization of the oxide layer from the onset of oxidation.
+Surface reactions dominate until the surface is saturated with oxygen and
+separated from the Si substrate by a \SI{5}{\angstrom} transition region. The
+saturated surface becomes inert to dissociative reactions and enables the
+diffusion of molecular oxygen to the \interface interface as assumed within the
+Deal-Grove model. Further oxidation of the Si substrate is then provided by
+O$_2$ dissociations at the interface due to the same charge transfer process
+responsible for the chemisorption at the surface.",2204.13954v2
+2023-02-13,The ignition of fine iron particles in the Knudsen transition regime,"A theoretical model is considered to predict the minimum ambient gas
+temperature at which fine iron particles can undergo thermal runaway--the
+ignition temperature. The model accounts for Knudsen transition transport
+effects, which become significant when the particle size is comparable to, or
+smaller than, the molecular mean free path of the surrounding gas. Two kinetic
+models for the high-temperature solid-phase oxidation of iron are analyzed. The
+first model (parabolic kinetics) considers the inhibiting effect of the iron
+oxide layers at the particle surface on the rate of oxidation, and a kinetic
+rate independent of the gaseous oxidizer concentration. The ignition
+temperature is solved as a function of particle size and initial oxide layer
+thickness with an unsteady analysis considering the growth of the oxide layers.
+In the small-particle limit, the thermal insulating effect of transition heat
+transport can lead to a decrease of ignition temperature with decreasing
+particle size. However, the presence of the oxide layer slows the reaction
+kinetics and its increasing proportion in the small-particle limit can lead to
+an increase of ignition temperature with decreasing particle size. This effect
+is observed for sufficiently large initial oxide layer thicknesses. The
+continuum transport model is shown to predict the ignition temperature of iron
+particles exceeding an initial diameter of 30 $\mu$m to a difference of 3% (30
+K) or less when compared to the transition transport model. The second kinetic
+model (first-order kinetics) considers a porous, non-hindering oxide layer, and
+a linear dependence of the kinetic rate of oxidation on the gaseous oxidizer
+concentration. The ignition temperature is resolved as a function of particle
+size with the transition and continuum transport models, and the differences
+between the ignition characteristics predicted by the two models are discussed.",2302.06704v1
+2013-04-01,A high-mobility two-dimensional electron gas at the heteroepitaxial spinel/perovskite complex oxide interface of γ-Al2O3/SrTiO3,"The discovery of two-dimensional electron gases (2DEGs) at the
+heterointerface between two insulating perovskite-type oxides, such as LaAlO3
+and SrTiO3, provides opportunities for a new generation of all-oxide electronic
+and photonic devices. However, significant improvement of the interfacial
+electron mobility beyond the current value of approximately 1,000 cm2V-1s-1 (at
+low temperatures), remains a key challenge for fundamental as well as applied
+research of complex oxides. Here, we present a new type of 2DEG created at the
+heterointerface between SrTiO3 and a spinel {\gamma}-Al2O3 epitaxial film with
+excellent quality and compatible oxygen ions sublattices. This
+spinel/perovskite oxide heterointerface exhibits electron mobilities more than
+one order of magnitude higher than those of perovskite/perovskite oxide
+interfaces, and demonstrates unambiguous two-dimensional conduction character
+as revealed by the observation of quantum magnetoresistance oscillations.
+Furthermore, we find that the spinel/perovskite 2DEG results from
+interface-stabilized oxygen vacancies and is confined within a layer of 0.9 nm
+in proximity to the heterointerface. Our findings pave the way for studies of
+mesoscopic physics with complex oxides and design of high-mobility all-oxide
+electronic devices.",1304.0336v1
+2014-04-16,Origin of High Temperature Oxidation Resistance of Ti-Al-Ta-N Coatings,"Alloying Ti-Al-N coatings with Ta has proven to enhance their hardness,
+thermal stability, and oxidation resistance. However, especially for
+arc-evaporated Ti-Al-Ta-N coatings only limited information on the detailed
+influence of the elements on various properties is available. Therefore, we
+have developed arc-evaporated Ti1-x-yAlxTayN coatings with various Al (x = 0.50
+- 0.65) and Ta (y = 0.00 - 0.15) contents. While the thermal stability of our
+coatings during annealing in inert He atmosphere increases with increasing Ta
+content, best results are obtained for specific Ta-Al ratios during oxidation.
+Single phase cubic Ti0.32Al0.60Ta0.08N yields a mass-gain of only ~5 % after 5
+h at 950 {\deg}C in synthetic air, whereas Ti0.35Al0.65N is completely oxidized
+after 15 min. This is in part based on the suppressed anatase and direct rutile
+TiO2 formation at a defined Ta-Al content. Consequently, the anatase-to-rutile
+transformation, generally observed for Ti1-xAlxN, is absent. This reduces the
+generation of pores and cracks within the oxide scale and especially at the
+nitride-oxide interface, leading to the formation of a protective rutile and
+corundum based oxide scale. This is also reflected in the pronounced decrease
+in activation energy for the protective scale formation from 232 kJ/mol for
+Ti0.35Al0.65N down to 14.5 kJ/mol for Ti0.32Al0.60Ta0.08N. Based on our results
+we can conclude that especially phase transformations within the oxide scale
+need to be suppressed, as the connected volume changes lead to the formation of
+cracks and pores.",1404.4345v1
+2015-02-02,Efficient Electro-Optical Modulation Based on Indium Tin Oxide,"We experimentally demonstrate several electro-optical modulators based on
+transparent conducting oxides. Our previous work demonstrated the modulator
+structure on glass substrate with broadband bias polarity-dependent modulation.
+Further exploration shows similar modulation effect of the modulator on quartz
+and silicon substrate.",1502.00651v1
+2015-02-22,Optimum High-k Oxide for the Best Performance of Ultra-scaled Double-Gate MOSFETs,"A widely used technique to mitigate the gate leakage in the ultra-scaled
+metal oxide semiconductor field effect transistors (MOSFETs) is the use of
+high-k dielectrics, which provide the same equivalent oxide thickness (EOT) as
+$\rm SiO_2$, but thicker physical layers. However, using a thicker physical
+dielectric for the same EOT has a negative effect on the device performance due
+to the degradation of 2D electrostatics. In this letter, the effects of high-k
+oxides on double-gate (DG) MOSFET with the gate length under 20 nm are studied.
+We find that there is an optimum physical oxide thickness ($\rm T_{OX}$) for
+each gate stack, including $\rm SiO_2$ interface layer and one high-k material.
+For the same EOT, $\rm Al_2O_3$ (k=9) over 3 $\rm\AA$ $\rm SiO_2$ provides the
+best performance, while for $\rm HfO_2$ (k=20) and $\rm La_2O_3$ (k=30), $\rm
+SiO_2$ thicknesses should be 5 $\rm\AA$ and 7 $\rm\AA$, respectively. The
+effects of using high-k oxides and gate stacks on the performance of
+ultra-scaled MOSFETs are analyzed. While thin oxide thickness increases the
+gate leakage, the thick oxide layer reduces the gate control on the channel.
+Therefore, the physical thicknesses of gate stack should be optimized to
+achieve the best performance.",1502.06178v1
+2016-05-26,Design of ternary alkaline-earth metal Sn(II) oxides with potential good p-type conductivity,"Oxides with good p-type conductivity have been long sought after to achieve
+high performance all-oxide optoelectronic devices. Divalent Sn(II) based oxides
+are promising candidates because of their rather dispersive upper valence bands
+caused by the Sn-5s/O-2p anti-bonding hybridization. There are so far few known
+Sn(II) oxides being p-type conductive suitable for device applications. Here,
+we present via first-principles global optimization structure searches a
+material design study for a hitherto unexplored Sn(II)-based system, ternary
+alkaline-earth metal Sn(II) oxides in the stoichiometry of MSn2O3 (M = Mg, Ca,
+Sr, Ba). We identify two stable compounds of SrSn2O3 and BaSn2O3, which can be
+stabilized by Sn-rich conditions in phase stability diagrams. Their structures
+follow the Zintl behaviour and consist of basic structural motifs of SnO3
+tetrahedra. Unexpectedly they show distinct electronic properties with band
+gaps ranging from 1.90 (BaSn2O3) to 3.15 (SrSn2O3) eV, and hole effective
+masses ranging from 0.87 (BaSn2O3) to above 6.0 (SrSn2O3) m0. Further
+exploration of metastable phases indicates a wide tunability of electronic
+properties controlled by the details of the bonding between the basic
+structural motifs. This suggests further exploration of alkaline-earth metal
+Sn(II) oxides for potential applications requiring good p-type conductivity
+such as transparent conductors and photovoltaic absorbers.",1605.08252v1
+2017-06-30,Graphene-Complex-oxide Nanoscale Device Concepts,"The integration of graphene with complex-oxide heterostructures such as
+LaAlO$_3$/SrTiO$_3$ offers the opportunity to combine the multifunctional
+properties of an oxide interface with the electronic properties of graphene.
+The ability to control interface conduction through graphene and understanding
+how it affects the intrinsic properties of an oxide interface are critical to
+the technological development of novel multifunctional devices. Here we
+demonstrate several device archetypes in which electron transport at an oxide
+interface is modulated using a patterned graphene top gate. Nanoscale devices
+are fabricated at the oxide interface by conductive atomic force microscope
+(c-AFM) lithography, and transport measurements are performed as a function of
+the graphene gate voltage. Experiments are performed with devices written
+adjacent to or directly underneath the graphene gate. Unique capabilities of
+this approach include the ability to create highly flexible device
+configurations, the ability to modulate carrier density at the oxide interface,
+and the ability to control electron transport up to the
+single-electron-tunneling regime, while maintaining intrinsic transport
+properties of the oxide interface. Our results facilitate the design of a
+variety of nanoscale devices that combine unique transport properties of these
+two intimately coupled two-dimensional electron systems.",1706.10254v2
+2017-09-06,Silicon-Oxide Interfaces: Structure and Electronic Properties,"The paper reviews methods used to study the electronic and structural
+properties of silicon/insulator interfaces. Methodological approaches to study
+the interface states and charge trapping in the oxide are considered. An
+overview of archetypical structural defects of the Si/SiO2 interface is given.",1709.01917v1
+2019-03-21,Doped-MoSe2 nanoflakes/3d metal oxide-hydr(oxy)oxides hybrid catalysts for pH-universal electrochemical hydrogen evolution reaction,"Clean hydrogen production through efficient and cost-effective
+electrochemical water splitting is highly promising to meeting future global
+energy demands. The design of Earth-abundant materials with both high activity
+for hydrogen evolution reaction (HER) and electrochemical stability in both
+acidic and alkaline environments summarize the outcomes needed for practical
+applications. Here, we report a non-noble 3d metal Cl-chemical doping of liquid
+phase exfoliated single/few-layer flakes of MoSe2 for creating MoSe2
+nanoflakes/3d metal oxide-hydr(oxy)oxide hybrid HER-catalysts. We propose that
+the electron-transfer from MoSe2 nanoflakes to metal cations and the chlorine
+complexation-induced both neutralization, as well as the in situ formation of
+metal oxide-hydr(oxy)oxides on MoSe2 nanoflake's surface, tailor the proton
+affinity of the derived catalysts, increasing the number and HER-kinetic of
+their active sites in both acidic and alkaline electrolytes. The
+electrochemical coupling between the doped-MoSe2 nanoflakes/metal
+oxide-hydr(oxy)oxide hybrids and single-walled carbon nanotubes
+heterostructures further accelerates the HER process. Lastly, monolithic
+stacking of multiple heterostructures is reported as a facile electrode
+assembly strategy to achieve overpotential for a cathodic current density of
+10mAcm-2 of 0.081V and 0.064V in 0.5M H2SO4 and 1M KOH, respectively. This
+opens up new opportunities to address the current density vs. overpotential
+requirements targeted in pH-universal H2 production.",1903.08947v1
+2020-08-24,Bond Synergy Model for Bond Energies in Alloy Oxides,"In this work we introduce a metal-oxide bond-energy model for alloy oxides
+based on pure-phase bond energies and bond synergy factors that describe the
+effect of alloying on the bond energy between cations and oxygen, an important
+quantity to understand formation and stability of passive films. This model is
+parameterized for binary cation-alloy oxides using density-functional theory
+energies and is shown to be directly transferable to multi-component alloy
+oxides. We parameterized the model for alloy oxide energies with metal cations
+that form the basis of corrosion resistant alloys, including Fe, Ni, Cr, Mo,
+Mn, W, Co, and Ru. We find that isoelectronic solutes allow quantification of
+pure-phase bond energies in oxides and that the calculated bond energy values
+give sensible results compared to common experience, including the role of Cr
+as the passive-layer former in Fe-Ni-Cr alloys for corrosion applications.
+Additionally, the bond synergy factors give insights into the mutual
+strengthening and weakening effects of alloying on cation-oxygen bonds and can
+be related to enthalpy of mixing and charge neutrality constraints. We
+demonstrate how charge neutrality can be identified and achieved by the
+oxidation states that the different cations assume depending on alloy
+composition and the presence of defects.",2008.10172v1
+2021-08-04,Comprehensive study of amorphous metal oxide and Ta$_2$O$_5$-based mixed oxide coatings for gravitational-wave detectors,"High finesse optical cavities of current interferometric gravitational-wave
+detectors are significantly limited in sensitivity by laser quantum noise and
+coating thermal noise. The thermal noise is associated with internal energy
+dissipation in the materials that compose the test masses of the
+interferometer. Our understanding of how the internal friction is linked to the
+amorphous material structure is limited due to the complexity of the problem
+and the lack of studies that span over a large range of materials. We present a
+systematic investigation of amorphous metal oxide and Ta$_2$O$_5$-based mixed
+oxide coatings to evaluate their suitability for low Brownian noise
+experiments. It is shown that the mechanical loss of metal oxides is correlated
+to their amorphous morphology, with continuous random network materials such as
+SiO$_2$ and GeO$_2$ featuring the lowest loss angles. We evaluated different
+Ta$_2$O$_5$-based mixed oxide thin films and studied the influence of the
+dopant in the optical and elastic properties of the coating. We estimated the
+thermal noise associated with high-reflectance multilayer stacks that employ
+each of the mixed oxides as the high index material. We concluded that the
+current high index material of TiO$_2$-doped Ta$_2$O$_5$ is the optimal choice
+for reduced thermal noise among Ta$_2$O$_5$-based mixed oxide coatings with low
+dopant concentrations.",2108.02127v1
+2021-10-22,Design and realization of Ohmic and Schottky interfaces for oxide electronics,"Understanding band alignment and charge transfer at complex oxide interfaces
+is critical to tailoring and utilizing their diverse functionality. Towards
+this goal, we design and experimentally validate both Ohmic- and Schottky-like
+charge transfers at oxide/oxide semiconductor/metal interfaces. We utilize a
+method for predicting band alignment and charge transfer in ABO3 perovskites,
+where previously established rules for simple semiconductors fail. The
+prototypical systems chosen are the rare class of oxide metals, SrBO3 with
+B=V-Ta, when interfaced with the multifaceted semiconducting oxide, SrTiO3. For
+B=Nb and Ta, we confirm that a large accumulation of charge occurs in SrTiO3
+due to higher energy Nb and Ta d-states relative to Ti; this gives rise to a
+high mobility metallic interface, which is an ideal epitaxial oxide/oxide Ohmic
+contact. On the other hand, for B=V, there is no charge transfer into the
+SrTiO3 interface, which serves as a highly conductive epitaxial gate metal.
+Going beyond these specific cases, this work opens the door to integrating the
+vast phenomena of ABO3 perovskites into a wide range of practical devices.",2110.12032v1
+2021-10-28,A Quantitative Analysis of the Ignition Characteristics of Fine Iron Particles,"Ignition of iron particles in an oxidizing environment marks the onset of a
+self-sustained combustion. The objective of the current study is to
+quantitatively examine the ignition characteristics of fine iron particles
+governed by the kinetics of solid-phase iron oxidation. The oxidation rates are
+inversely proportional to the thickness of the oxide layer and calibrated using
+the experimentally measured growth of iron-oxide layers over time. Steady-state
+and unsteady analysis have been performed to probe the dependence of the
+critical gas temperature required to trigger a thermal runaway (namely, the
+ignition temperature $T_\mathrm{ign}$) on particle size, initial thickness of
+oxide layer, inert gas species, radiative heat loss, and the collective heating
+effect in a suspension of particles. Both analyses indicate that
+$T_\mathrm{ign}$ depends on $\delta_0$, i.e., the ratio between the initial
+oxide layer thickness and particle size, regardless of the absolute size of the
+particle. The unsteady analysis predicts that, for $\delta_0 \lesssim 0.003$,
+$T_\mathrm{ign}$ becomes independent of $\delta_0$. Under standard conditions
+in air, $T_\mathrm{ign}$ is approximately 1080 K for any particle size greater
+than 5 microns. Radiative heat loss has a minor effect on $T_\mathrm{ign}$. The
+collective effect of a suspension of iron particles in reducing
+$T_\mathrm{ign}$ is demonstrated. The transition behavior between
+kinetic-controlled and external-diffusion-controlled combustion regimes of an
+ignited iron particle is systematically examined. The influences of initial
+oxide-layer thickness and particle temperature on the ignition delay time,
+$\tau_\mathrm{ign}$, of iron particles are parametrically probed. A $d^2$-law
+scaling between $\tau_\mathrm{ign}$ and particle size is identified.",2110.15461v2
+2022-01-31,Ti Passivation from a Dissipative Structure of the Oxide Layer,"For the long-standing riddle of metallic passivation, the second law of
+thermodynamics helps little. But this study shows that Ti passivation layer
+coming from room-temperature spontaneous oxidation possesses a dissipative
+structure which naturally extends from the lattice structure of Ti matrix.
+Macroscopically, its oxidation degree, oxygen content and amorphous structures
+exhibit a gradient decline from its surface to its bottom. Beneath a stable
+chemisorbed oxygen-metal atom monolayer, residue Ti lattice structures resemble
+stones and amorphous structures composed of TiO2, Ti2O3 and TiO resemble
+mortar, together they forming a heterogeneous stone-wall like structure. The
+rapid formation of the stable chemisorbed monolayer passivates the outmost Ti
+atoms to start Ti passivation, and subsequently a dissipative mechanism of
+oxidation cracks the Ti lattice structures and thus the oxide layer is formed
+and effect passivation. The solid phase formed by the open, stable,
+macroscopically-ordered, non-equilibrium oxide film, which can be aptly called
+""the dissipative oxidation phase"", theoretically does not end in complete
+oxidation of thermodynamic stability. This study derails both the adsorption
+theory of passivation and the theory of passivity film, and thus sheds new
+light on the metallic passivation.",2201.12964v1
+2022-12-13,On the evolution of oxidative etching of few layer graphene (FLG) in FLG /TiO$_2$ nanocomposites. Interfacial dipole signature and chemical shift in C1s X-ray photoemission spectra,"We present the effect of oxidative etching in FLG/TiO$_2$ hybrids on FLG
+edges chemistry/morphology addressing also the catalytic activity of TiO$_2$
+NPs. According to the XPS and TGA analysis the oxidation degree strongly
+depends on TiO$_2$:FLG ratio. The preparation of two series of FLG/TiO$_2$
+hybrids via sol-gel method and in-situ oxidation permitted to correctly
+describe and distinguish the chemical composition, core shift and charge
+distribution in C1s XPS with Tip peak as reference. Such analysis is
+challenging in carbon materials due the overlapping of C1s peaks from the
+sample and adventitious carbon reference. We claim the formation of interfacial
+dipole as possible direct signature of charge transfer from TiO$_2$ to FLG. A
+downward shift of C1s (sp$^2$C) up to 1.4 eV is measured and contributions of
+non sp$^2$C are determined in the composites. The modifications related to the
+oxidation are supported by TEM/SEM observations, and referred to non-catalytic
+oxidation and oxidation in mechanically mixed components.
+  KEYWORDS: oxidative etching, graphene edges, TiO$_2$ catalyst, interfacial
+dipole, XPS, charge transfer",2212.06697v1
+2023-01-25,"Bioabsorbable WE43 Mg alloy wires modified by continuous plasma-electrolytic oxidation for implant applications. Part I: processing, microstructure and mechanical properties","In our work, a novel processing strategy for the continuous fabrication and
+surface modification of wires from Magnesium alloy WE43 by means of
+plasma-electrolytic oxidation (PEO) is presented. In the first step, wires with
+a strong basal texture and small grain size ($\approx$ 1 $\mu$m) were
+manufactured by combined cold drawing and in-line stress-relief heat treatment
+steps that optimized the mechanical properties (in terms of strength and
+ductility) by means of annealing. In a second step, and to the best of our
+knowledge for the first time ever, the wires were continuously surface-modified
+with a novel plasma electrolytic oxidation process, which was able to create a
+homogeneous porous oxide layer made of MgO and Mg$_3$(PO4)$_2$ on the wire
+surface. While the oxide layer slightly diminished the tensile properties, the
+strength of the surface-modified wires could be maintained close to 300 MPa
+with a strain-to-failure $\approx$ 8\%. Furthermore, the thickness of the oxide
+layer could be controlled by immersion time within the electrolytic bath and
+was adjusted to realize a thicknesses of $\approx$ 8 $\mu$m, which could be
+obtained in $<$ 20 s. Our experiments showed that the chemical composition,
+morphology and porosity of the oxide layer could be tailored by changing
+electrical parameters. The combined cold drawing and heat treatment process
+with additional continuous plasma electrolytic oxidation processing can be
+upscaled to produce a novel generation of bioabsorbable Mg wires with optimized
+mechanical, degradation and biological performance for use in biomedical
+applications.",2301.10479v1
+2023-07-27,Super-tetragonal Sr4Al2O7: a versatile sacrificial layer for high-integrity freestanding oxide membranes,"Releasing the epitaxial oxide heterostructures from substrate constraints
+leads to the emergence of various correlated electronic phases and paves the
+way for integrations with advanced semiconductor technologies. Identifying a
+suitable water-soluble sacrificial layer, compatible with the high-quality
+epitaxial growth of oxide heterostructures, is currently the key to the
+development of large-scale freestanding oxide membranes. In this study, we
+unveil the super-tetragonal Sr4Al2O7 (SAOT) as a promising water-soluble
+sacrificial layer. The distinct low-symmetric crystal structure of SAOT enables
+a superior capability to sustain epitaxial strain, thus allowing for broad
+tunability in lattice constants. The resultant structural coherency and
+defect-free interface in perovskite ABO3/SAOT heterostructures effectively
+restrain crack formations during the water-assisted release of freestanding
+oxide membranes. For a variety of non-ferroelectric oxide membranes, the
+crack-free areas can span up to a few millimeters in length scale. These
+compelling features, combined with the inherent high-water solubility, make
+SAOT a versatile and feasible sacrificial layer for producing high-quality
+freestanding oxide membranes, thereby boosting their potential for innovative
+oxide electronics and flexible device designs.",2307.14966v2
+2003-04-08,Oxide formation at the surface of late 4d transition metals: Insights from first-principles atomistic thermodynamics,"Using density-functional theory we assess the stability of bulk and surface
+oxides of the late 4d transition metals in a ``constrained equilibrium'' with a
+gas phase formed of O2 and CO. While the stability range of the most stable
+bulk oxide extends for ruthenium well into gas phase conditions representative
+of technological CO oxidation catalysis, this is progressively less so for the
+4d metals to its right in the periodic system. Surface oxides could
+nevertheless still be stable under such conditions. These thermodynamic
+considerations are discussed in the light of recent experiments, emphasizing
+the role of (surface) oxides as the active phase of model catalysts formed from
+these metals.",0304184v1
+2003-11-24,Kinetic hindrance during the initial oxidation of Pd(100) at ambient pressures,"The oxidation of the Pd(100) surface at oxygen pressures in the 10^-6 to 10^3
+mbar range and temperatures up to 1000 K has been studied in-situ by surface
+x-ray diffraction (SXRD). The results provide direct structural information on
+the phases present in the surface region and on the kinetics of the oxide
+formation. Depending on the (T,p) environmental conditions we either observe a
+thin sqrt(5) x sqrt(5) R27 surface oxide or the growth of a rough, poorly
+ordered bulk oxide film of PdO predominantly with (001) orientation. By either
+comparison to the surface phase diagram from first-principles atomistic
+thermodynamics or by explicit time-resolved measurements we identify a strong
+kinetic hindrance to the bulk oxide formation even at temperatures as high as
+675 K.",0311541v1
+2004-06-23,White Lines and 3d-Occupancy for the 3d Transition-Metal Oxides,"Electron energy-loss spectrometry was employed to measure the white lines at
+the L23 absorption edges of the 3d transition-metal oxides and lithium
+transition-metal oxides. The white-line ratio (L3/L2) was found to increase
+between d^0 and d^5 and decrease between d^5 and d^10, consistent with previous
+results for the transition metals and their oxides. The intensities of the
+white lines, normalized to the post-edge background, are linear for the 3d
+transition-metal oxides and lithium transition-metal oxides. An empirical
+correlation between normalized white-line intensity and 3d occupancy is
+established. It provides a method for measuring changes in the 3d-state
+occupancy. As an example, this empirical relationship is used to measure
+changes in the transition-metal valences of Li_{1-x}Ni_{0.8}Co_{0.2}O_2 in the
+range of 0 < x < 0.64. In these experiments the 3d occupancy of the nickel ion
+decreased upon lithium deintercalation, while the cobalt valence remained
+constant.",0406561v1
+2005-03-18,"Oxide nanotemplates for self-assembling ""solid"" building blocks","It is widely accepted that self-assembling building blocks is one of the
+promising ways for engineering new materials. Recent years reveal substantial
+progress in fabricating colloidal particles, polymer blocks and supramolecular
+aggregates of organic molecules. Despite of substantial progress in molecular
+self-assembly there is still a lack of simple blocks made of ""solid matter""
+(e.g. metals, oxides etc.) with well-defined crystal structure and spatial
+order. Here we demonstrate that ordered arrays of metal nanoclusters can be
+fabricated by self-assembly on a wide range of oxide templates. These
+nano-templates are produced either by depositing an alien oxide film or by
+oxidizing a metal/metal oxide substrate.",0503484v2
+2005-07-11,Precipitation-Redispersion of Cerium Oxide Nanoparticles with Poly(Acrylic Acid) : Towards Stable Dispersions,"We exploit a precipitation-redispersion mechanism for complexation of short
+chain polyelectrolytes with cerium oxide nanoparticles to extend their
+stability ranges. As synthesized, cerium oxide sols at pH 1.4 consist of
+monodisperse cationic nanocrystalline particles having a hydrodynamic diameter
+of 10 nm and a molecular weight 400000 gmol-1. We show that short chain
+uncharged poly(acrylic acid) at low pH when added to a cerium oxide sols leads
+to macroscopic precipitation. As the pH is increased, the solution
+spontaneously redisperses into a clear solution of single particles with an
+anionic poly(acrylic acid) corona. The structure and dynamics of cerium oxide
+nanosols and their hybrid polymer-inorganic complexes in solution are
+investigated by static and dynamic light scattering, X-ray scattering, and by
+chemical analysis. Quantitative analysis of the redispersed sol gives rise to
+an estimate of 40 - 50 polymer chains per particle for stable suspension. This
+amount represents 20 % of the mass of the polymer-nanoparticle complexes. This
+complexation adds utility to the otherwise unstable cerium oxide dispersions by
+extending the range of stability of the sols in terms of pH, ionic strength and
+concentration.",0507238v2
+2006-01-31,Local oxidation of Ga[Al]As heterostructures with modulated tip-sample voltages,"Nanolithography based on local oxidation with a scanning force microscope has
+been performed on an undoped GaAs wafer and a Ga[Al]As heterostructure with an
+undoped GaAs cap layer and a shallow two-dimensional electron gas. The oxide
+growth and the resulting electronic properties of the patterned structures are
+compared for constant and modulated voltage applied to the conductive tip of
+the scanning force microscope. All the lithography has been performed in
+non-contact mode. Modulating the applied voltage enhances the aspect ratio of
+the oxide lines, which significantly strengthens the insulating properties of
+the lines on GaAs. In addition, the oxidation process is found to be more
+reliable and reproducible. Using this technique, a quantum point contact and a
+quantum wire have been defined and the electronic stability, the confinement
+potential and the electrical tunability are demonstrated to be similar to the
+oxidation with constant voltage.",0601704v1
+2008-11-27,Two-dimensional manganese oxide nanolayers on Pd(100): Surface phase diagram,"Two-dimensional manganese oxide layers have been grown on Pd(100) and have
+been characterized by scanning tunnelling microscopy (STM), low-energy electron
+diffraction (LEED) and X-ray photoelectron spectroscopy (XPS). The complex
+surface phase diagram of MnOx on Pd(100) is reported, where nine different
+novel Mn oxide phases have been detected as a function of the chemical
+potential of oxygen mO. Three regions of the chemical potential of oxygen can
+be identified, in which structurally related oxide phases are formed, often in
+coexistence at the surface. The different regions of mO are reflected in the
+oxidation states of the respective Mn oxide nanolayers as revealed by the Mn 2p
+and O 1s XPS binding energies. The MnOx nanolayers form two-dimensional wetting
+layers and it is speculated that they mediate the epitaxial growth of MnO on
+Pd(100) by providing structurally graded interfaces.",0811.4555v1
+2009-03-23,Modeling of autoignition and NO sensitization for the oxidation of IC engine surrogate fuels,"This paper presents an approch for modeling with one single kinetic mechanism
+the chemistry of the autoignition and combustion processes inside an internal
+combustion engine, as well as the chemical kinetics governing the
+post-oxidation of unburned hydrocarbons in engine exhaust gases. Therefore a
+new kinetic model was developed, valid over a wide range of temperatures
+including the negative temperature coefficient regime. The model simulates the
+autoignition and the oxidation of engine surrogate fuels composed of n-heptane,
+iso-octane and toluene, which are sensitized by the presence of nitric oxides.
+The new model was obtained from previously published mechanisms for the
+oxidation of alkanes and toluene where the coupling reactions describing
+interactions between hydrocarbons and NOx were added. The mechanism was
+validated against a wide range of experimental data obtained in jet-stirred
+reactors, rapid compression machines, shock tubes and homogenous charge
+compression ignition engines. Flow rate and sensitivity analysis were performed
+in order to explain the low temperature chemical kinetics, especially the
+impact of NOx on hydrocarbon oxidation.",0903.3809v1
+2009-10-14,Experimental study of the interfacial cobalt oxide in Co3O4/a-Al2O3(0001) epitaxial films,"A detailed spectroscopic and structural characterization of ultrathin cobalt
+oxide films grown by O-assisted molecular beam epitaxy on a-Al2O3(0001) single
+crystals is reported. The experimental results show that the cobalt oxide films
+become progressively more disordered with increasing thickness, starting from
+the early stages of deposition. Low energy electron diffraction patterns
+suggest that the unit cell remains similar to that of a-Al2O3(0001) up to a
+thickness of 17 A, while at larger thicknesses a pattern identified with that
+of Co3O4(111) becomes visible. X-ray photoelectron spectroscopy reveals sudden
+changes in the shape of the Co 2p lines from 3.4 to 17 A cobalt oxide
+thickness, indicating the transition from an interfacial cobalt oxide layer
+towards [111]-oriented Co3O4. In particular, the absence of characteristic
+satellite peaks in the Co 2p lines indicates the formation of a trivalent,
+octahedrally coordinated, interfacial cobalt oxide layer during the early
+stages of growth, identified as the Co2O3 corundum phase.",0910.2647v1
+2010-02-04,Activated O2 dissociation and formation of oxide islands on the Be(0001) surface: Another atomistic model for metal oxidation,"By simulating the dissociation of O2 molecules on the Be(0001) surface using
+the first-principles molecular dynamics approach, we propose a new atomistic
+model for the surface oxidation of sp metals. In our model, only the
+dissociation of the first oxygen molecule needs to overcome an energy barrier,
+while the subsequent oxygen molecules dissociate barrierlessly around the
+adsorption area. Consequently, oxide islands form on the metal surface, and
+grow up in a lateral way. We also discover that the firstly dissociated oxygen
+atoms are not so mobile on the Be(0001) surface, as on the Al(111) surface. Our
+atomistic model enlarges the knowledge on metal surface oxidations by perfectly
+explaining the initial stage during the surface oxidation of Be, and might be
+applicable to some other sp metal surfaces.",1002.0967v2
+2010-11-19,Bond-specific reaction kinetics during the oxidation of (111) Si: Effect of n-type doping,"It is known that a higher concentration of free carriers leads to a higher
+oxide growth rate in the thermal oxidation of silicon. However, the role of
+electrons and holes in oxidation chemistry is not clear. Here, we report
+real-time second-harmonic-generation data on the oxidation of H-terminated
+(111)Si that reveal that high concentrations of electrons increase the chemical
+reactivity of the outer-layer Si-Si back bonds relative to the Si-H up bonds.
+However, the thicknesses of the natural oxides of all samples stabilize near 1
+nm at room temperature, regardless of the chemical kinetics of the different
+bonds.",1011.4386v1
+2011-02-01,Universality of transport properties of ultra-thin oxide films,"We report low-temperature measurements of current-voltage characteristics for
+highly conductive Nb/Al-AlOx-Nb junctions with thicknesses of the Al interlayer
+ranging from 40 to 150 nm and ultra-thin barriers formed by diffusive oxidation
+of the Al surface. In the superconducting state these devices have revealed a
+strong subgap current leakage. Analyzing Cooper-pair and quasiparticle currents
+across the devices, we conclude that the strong suppression of the subgap
+resistance comparing with conventional tunnel junctions originates from a
+universal bimodal distribution of transparencies across the Al-oxide barrier
+proposed earlier by Schep and Bauer. We suggest a simple physical explanation
+of its source in the nanometer-thick oxide films relating it to strong local
+barrier-height fluctuations which are generated by oxygen vacancies in thin
+aluminum oxide tunnel barriers formed by thermal oxidation.",1102.0139v2
+2012-11-20,Full field chemical imaging of buried native sub-oxide layers on doped silicon patterns,"Fully energy-filtered X-ray photoelectron emission microscopy is used to
+analyze the spatial distribution of the silicon sub-oxide structure at the
+SiO2/Si interface as a function of underlying doping pattern. Using a
+spectroscopic pixel-by-pixel curve fitting analysis, we obtain the sub-oxide
+binding energy and intensity distributions over the full field of view. Binding
+energy maps for each oxidation state are obtained with a spatial resolution of
+120 nm. Within the framework of a five-layer model, the experimental data are
+used to obtain quantitative maps of the sub-oxide layer thickness and also
+their spatial distribution over the p-n junctions. Variations in the sub-oxide
+thicknesses are found to be linked to the level and type of doping. The
+procedure, which takes into account instrumental artefacts, enables the
+quantitative analysis of the full 3D dataset.",1211.4724v1
+2013-01-15,Oxidation of In2S3 films to synthetize In2S3(1-x)O3x thin films as a buffer layer in solar cells,"In2S3(1-x)O3x is known from preceding studies to have a bandgap varying
+continuously as a function of x, the reason why this solid solution is
+potentially interesting in the field of photovoltaics. In this work, we present
+results on oxidation of In2S3 by heating in air atmosphere to obtain the
+desired material. The oxidation is accompanied by a mass loss due to the
+substitution of S by O atoms that is studied by means of thermogravimetric
+analysis. It appears that the temperature region in which the oxidation occurs
+is strongly dependent on the texture of deposited films. As-grown films
+deposited by chemical bath deposition are subjected to nano-oxidation occurring
+at lower temperature than oxidation of materials that are characterized by a
+better crystallinity and larger crystallite size. X ray diffraction and
+scanning electron microscopy (including EDX) were used to get information on
+the compounds and the texture of films. The main conclusion of the paper opens
+the perspective of practical applications for producing layers for solar cells.",1301.3467v2
+2013-03-29,Adsorbate-Mediated Growth of Rare-Earth Oxides on Silicon,"Ultrathin cerium oxide films have been deposited on chlorine, gallium, and
+silver passivated Si(111) by reactive molecular beam epitaxy in a comparative
+study. The crystallinity of these films has been characterized by x-ray
+standing waves while the oxidation state of the rare-earth oxide (REOx) films
+and the chemical interface composition have been revealed by hard x-ray
+photoelectron spectroscopy. The use of Cl as passivating agent results in the
+epitaxial growth of highly crystalline REOx films with the RE metal in the 3+
+oxidation state while effectively suppressing silicate and silicon oxide
+formation at the interface. In contrast, Ga and Ag preadsorption yield films of
+inferior quality, in the case of Ag of even lower crystallinity than without
+passivation. Further investigations show that Cl-passivation also results in
+ultrathin lanthana films of superior quality, which facilitate the growth of
+well-ordered ceria on lanthana REOx multilayers.",1303.7414v1
+2013-12-27,Characterization of low-temperature microwave loss of thin aluminum oxide formed by plasma oxidation,"We report on the characterization of microwave loss of thin aluminum oxide
+films at low temperatures using superconducting lumped resonators. The oxide
+films are fabricated using plasma oxidation of aluminum and have a thickness of
+5 nm. We measure the dielectric loss versus microwave power for resonators with
+frequencies in the GHz range at temperatures from 54 to 303 mK. The power and
+temperature dependence of the loss is consistent with the tunneling two-level
+system theory. These results are relevant to understanding decoherence in
+superconducting quantum devices. The obtained oxide films are thin and robust,
+making them suitable for capacitors in compact microwave resonators.",1312.7362v1
+2014-09-03,Dynamics of stress p53: Nitric oxide induced transition of states and synchronization,"We study the temporal and the synchronous behaviours in p53-Mdm2 regulatory
+network due to the interaction of its complex network components with the
+nitric oxide molecule. In single cell process, increase in nitric oxide
+concentration gives rise the transition to various p53 temporal behaviours,
+namely fixed point oscillation, damped oscillation and sustain oscillation
+indicating stability, weakly activated and strongly activated states. The noise
+in stochastic system is found to help to reach these states much faster as
+compared to deterministic case which is evident from permutation entropy
+dynamics. In coupled system with nitric oxide as diffusively coupling molecule,
+we found nitric oxide as strong coupling molecule within a certain range of
+coupling strength \epsilon beyond which it become weak synchronizing agent. We
+study these effects by using correlation like synchronization indicator \gamma
+obtained from permutation entropies of the coupled system, and found five
+important regimes in (\epsilon-\gamma) phase diagram, indicating
+desynchronized, transition, strongly synchronized, moderately synchronized and
+weakly synchronized regimes respectively. We claim that there is the
+competition between the toxicity and the synchronizing role of nitric oxide
+that lead the cell in different stressed conditions.",1409.1944v1
+2014-09-25,Characterization of Interface Traps in SiO$_2$/SiC Structures Close to the Conduction Band by Deep-Level Transient Spectroscopy,"The effects of the oxidation atmosphere and crystal faces on the
+interface-trap density was examined by using constant-capacitance deep-level
+transient spectroscopy to clarify the origin of them. By comparing the DLTS
+spectra of the low-mobility interfaces oxidized in a N$_2$O atmosphere with
+those of the high-mobility interfaces on C-face oxidized in a wet atmosphere,
+it was found that a high density of traps are commonly observed around the
+energy of 0.16 eV from the edge of the conduction band ($C1$ traps) in
+low-mobility interfaces irrespective of crystal faces. It was also found that
+the generation and elimination of traps specific to crystal faces: (1) the $C1$
+traps can be eliminated by wet oxidation only on the C-face, and (2) the $O2$
+traps (0.37 eV) can be observed in the SiC/SiO$_2$ interface only on the
+Si-face. The generation of $O2$ traps on the Si-face and the elimination of
+$C1$ traps on the C-face by wet oxidation may be caused by the oxidation
+reaction specific to the crystal faces.",1409.7170v1
+2015-02-25,Porous nanostructured metal oxides synthesized through atomic layer deposition on a carbonaceous template followed by calcination,"Porous metal oxides with nano-sized features attracted intensive interest in
+recent decades due to their high surface area which is essential for many
+applications, e.g. Li ion batteries, photocatalysts, fuel cells and
+dye-sensitized solar cells. Various approaches were so far investigated to
+synthesize porous nanostructured metal oxides, including self-assembly and
+template-assisted synthesis. For the latter approach, forests of carbon
+nanotubes are considered as particularly promising templates, with respect to
+their one dimensional nature and the resulting high surface area. In this work,
+we systematically investigate the formation of porous metal oxides (Al2O3,
+TiO2, V2O5 and ZnO) with different morphologies using atomic layer deposition
+on multi-walled carbon nanotubes followed by post deposition calcination. X-ray
+diffraction, scanning electron microscopy accompanied with X-ray energy
+dispersive spectroscopy and transmission electron microscopy were used for the
+investigation of morphological and structural transitions at the micro- and
+nano-scale during the calcination process. The crystallization temperature and
+the surface coverage of the metal oxides and the oxidation temperature of the
+carbon nanotubes were found to produce significant influence on the final
+morphology.",1502.07233v1
+2015-02-26,"Chemical interaction, space-charge layer and molecule charging energy for metal oxide / organic interfaces","Three driving forces control the energy level alignment between
+transition-metal oxides and organic materials: the chemical interaction between
+the two materials, the organic electronegativity and the possible space charge
+layer formed in the oxide. This is illustrated in this letter by analyzing
+experimentally and theoretically a paradigmatic case, the TiO2(110) / TCNQ
+interface: due to the chemical interaction between the two materials, the
+organic electron affinity level is located below the Fermi energy of the
+n-doped TiO2. Then, one electron is transferred from the oxide to this level
+and a space charge layer is developed in the oxide inducing an important
+increase in the interface dipole and in the oxide work function.",1502.07554v1
+2015-04-23,Interfacial Effects on the Optical Properties of CdTe/CdS Quantum Dots,"Using a combination of continuous wave and time-resolved spectroscopy, we
+study the effects of interfacial conditions on the radiative lifetimes and
+photoluminescence intensities of colloidal CdTe/CdS quantum dots (QDs) embedded
+in a three-dimensional nanostructured silicon (NSi) matrix. The NSi matrix was
+thermally oxidized under different conditions to change the interfacial oxide
+thickness. QDs embedded in a NSi matrix with ~0.5 nm of interfacial oxide
+exhibited reduced photoluminescence intensity and nearly five times shorter
+radiative lifetimes (~16 ns) compared to QDs immobilized within completely
+oxidized, nanostructured silica (NSiO2) frameworks (~78 ns). Optical absorption
+by the sub-nm oxidized NSi matrix partially lowers QD emission intensities
+while non-radiative carrier recombination and phonon assisted transitions
+influenced by defect sites within the oxide and NSi are believed to be the
+primary factors limiting the QD exciton lifetimes in the heterostructures.",1504.06269v1
+2015-08-14,In-situ Raman study of laser-induced graphene oxidation,"We present in-situ Raman measurements of laser-induced oxidation in
+exfoliated single-layer graphene. By using high-power laser irradiation, we can
+selectively and in a controlled way initiate the oxidation process and
+investigate its evolution over time. Our results show that the laser-induced
+oxidation process is divided into two separate stages, namely tensile strain
+due to heating and subsequent $p$-type doping due to oxygen binding. We discuss
+the temporal evolution of the $D/G$-mode ratio during oxidation and explain the
+unexpected steady decrease of the defect-induced $D$ mode at long irradiation
+times. Our results provide a deeper understanding of the oxidation process in
+single-layer graphene and demonstrate the possibility of sub-$\mu$m patterning
+of graphene by an optical method.",1508.03457v1
+2015-08-19,Combinatorial approach for development of new metal oxides materials for all oxide photovoltaics,"The combinatorial approach to all oxide material and device research is based
+on the synthesis of hundreds of related materials in a single experiment. This
+approach requires the development of new tools to rapidly characterize these
+materials libraries and new techniques to analyze the resulting data. The
+research presented here is intended to make a contribution towards meeting this
+demand, and thereby advance the pace of materials research. In many cases
+photovoltaic determinations are well-suited for high throughput methodologies,
+enabling direct quantitative analysis of properties whose implementation I
+demonstrate my thesis. This thesis focuses on the development and utilization
+of high throughput and combinatorial methods that have incorporated, or are
+associated with, the all-oxide photovoltaic field. The development of new
+absorbers often requires novel buffer layers, contact materials, and interface
+engineering. The importance and contribution of the combinatorial material
+science approach for the development and rapid characterization of new and
+known metal oxide thin films for all oxide photovoltaics have been shown and
+discussed in my thesis.",1508.04626v1
+2015-09-24,Selective electrochemical generation of hydrogen peroxide from water oxidation,"Water is a life-giving source, fundamental to human existence, yet, over a
+billion people lack access to clean drinking water. Present techniques for
+water treatment such as piped, treated water rely on time and resource
+intensive centralized solutions. In this work, we propose a decentralized
+device concept that can utilize sunlight to split water into hydrogen and
+hydrogen peroxide. The hydrogen peroxide can oxidize organics while the
+hydrogen bubbles out. In enabling this device, we require an electrocatalyst
+that can oxidize water while suppressing the thermodynamically favored oxygen
+evolution and form hydrogen peroxide. Using density functional theory
+calculations, we show that the free energy of adsorbed OH$^*$ can be used as a
+descriptor to screen for selectivity trends between the 2e$^-$ water oxidation
+to H$_2$O$_2$ and the 4e$^-$ oxidation to O$_2$. We show that materials that
+bind oxygen intermediates sufficiently weakly, such as SnO$_2$, can activate
+hydrogen peroxide evolution. We present a rational design principle for the
+selectivity in electrochemical water oxidation and identify new material
+candidates that could perform H$_2$O$_2$ evolution selectively.",1509.07444v1
+2016-01-21,Patterning of high mobility electron gases at complex oxide interfaces,"Oxide interfaces provide an opportunity for electronics. However, patterning
+of electron gases at complex oxide interfaces is challenging. In particular,
+patterning of complex oxides while preserving a high electron mobility remains
+underexplored and inhibits the study of quantum mechanical effects where
+extended electron mean free paths are paramount. This letter presents an
+effective patterning strategy of both the amorphous-LaAlO$_3$/SrTiO$_3$
+(a-LAO/STO) and modulation-doped amorphous-
+LaAlO$_3$/La$_{7/8}$Sr$_{1/8}$MnO$_3$/SrTiO$_3$ (a-LAO/LSM/STO) oxide
+interfaces. Our patterning is based on selective wet etching of amorphous-LSM
+(a-LSM) thin films which acts as a hard mask during subsequent depositions.
+Strikingly, the patterned modulation-doped interface shows electron mobilities
+up to ~8,700 cm$^2$/Vs at 2 K, which is among the highest reported values for
+patterned conducting complex oxide interfaces that usually are ~1,000 cm$^2$/Vs
+at 2 K.",1601.05571v1
+2016-06-17,Ultra-high oxidation potential of Ti/Cu-SnO2 anodes fabricated by spray pyrolysis for wastewater treatment,"High oxidation potential indicates anodes have high oxidation power and high
+current efficiency for organics oxidation. In this paper, we prepared
+Ti/Cu-SnO2 anodes using spray pyrolysis method. The Ti/Cu-SnO2 anodes have an
+ultra-high oxidation potential of about 2.7 V vs NHE, suitable for use in
+wastewater treatment. The Ti/Cu-SnO2 anodes exhibit the preferred orientation
+along (110) plane at high Cu doped concentration. First-principles calculations
+suggest that work function of Cu-SnO2 increases with the Cu doping
+concentration. It is obtained that the preferred (110) plane and the high work
+function are responsible for the enhanced oxidation potential of Ti/Cu-SnO2
+anodes.",1606.06332v1
+2016-09-21,Hollow carbon sphere/metal oxide nanocomposite anodes for lithium-ion batteries,"Hollow carbon spheres (HCS) covered with metal oxide nanoparticles (SnO2 and
+MnO2, respectively) were successfully synthesized and investigated regarding
+their potential as anode materials for lithium-ion batteries. Raman
+spectroscopy shows a high degree of graphitization for the HCS host structure.
+The mesoporous nature of the nanocomposites is confirmed by
+Brunauer-Emmett-Teller analysis. For both metal oxides under study, the metal
+oxide functionalization of HCS yields a significant increase of electrochemical
+performance. The charge capacity of HCS/SnO2 is 370 mAh/g after 45 cycles (266
+mAh/g in HCS/MnO2) which clearly exceeds the value of 188 mAh/g in pristine
+HCS. Remarkably, the data imply excellent long term cycling stability after 100
+cycles in both cases. The results hence show that mesoporous HCS/metal oxide
+nanocomposites enable exploiting the potential of metal oxide anode materials
+in Lithium-ion batteries by providing a HCS host structure which is both
+conductive and stable enough to accommodate big volume change effects.",1609.06523v1
+2019-05-29,The effect of atomic structure on the electrical response of aluminium oxide tunnel junctions,"Many nanoelectronic devices rely on thin dielectric barriers through which
+electrons tunnel. For instance, aluminium oxide barriers are used as Josephson
+junctions in superconducting electronics. The reproducibility and drift of
+circuit parameters in these junctions are affected by the uniformity,
+morphology, and composition of the oxide barriers. To improve these circuits
+the effect of the atomic structure on the electrical response of aluminium
+oxide barriers must be understood. We create three-dimensional atomistic models
+of aluminium oxide tunnel junctions and simulate their electronic transport
+properties with the non-equilibrium Green's function formalism. Increasing the
+oxide density is found to produce an exponential increase in the junction
+resistance. In highly oxygen-deficient junctions we observe metallic channels
+which decrease the resistance significantly. Computing the charge and current
+density within the junction shows how variation in the local potential
+landscape can create channels which dominate conduction. An atomistic approach
+provides a better understanding of these transport processes and guides the
+design of junctions for nanoelectronics applications.",1905.12214v1
+2020-07-20,Expanding materials selection via transfer learning for high-temperature oxide selection,"Materials with higher operating temperatures than today's state of the art
+can improve system performance in several applications and enable new
+technologies. Under most scenarios, a protective oxide scale with high melting
+temperatures and thermodynamic stability as well as low ionic diffusivity is
+required. Thus, the design of high-temperature systems would benefit from
+knowledge of these properties and related ones for all known oxides. While some
+properties of interest are known for many oxides (e.g. elastic constants exist
+for over 1,000 oxides), melting temperature is known for a relatively small
+subset. The determination of melting temperatures is time consuming and costly,
+both experimentally and computationally, thus we use data science tools to
+develop predictive models from the existing data. The relatively small number
+of available melting temperature values precludes the use of standard tools;
+therefore, we use a multi-step approach based on sequential learning where
+surrogate data from first-principles calculations is leveraged to develop
+models using small datasets. We use these models to predict the desired
+properties for nearly 11,000 oxides and quantify uncertainties in the space.",2007.12262v1
+2017-04-23,Band alignment of metal/amorphous-oxide interface using atomic orbitals projection of plane-wave: a first principle study at the Al/a-SiO2 interface,"Amorphous insulating oxides play a significant role in the contemporary
+electronic industry. Understanding the band alignment of heterogeneous
+interfaces containing amorphous structures helps to better control the carrier
+transport property at the interface. Classical band offset methods developed
+previously line-up eigenlevels with respect to an ideal bulk reference or
+vacuum level. However, the local disorder of amorphous structures makes the
+bulk reference ambiguous. Therefore, classical methods cannot be applied. In
+this study, we introduce a new approach based on the Linear Combination of
+Atomic Orbital (LCAO) projection of wave-function to line-up bands at
+metal/oxide interfaces. The LCAO projection of wave-function accounts for all
+metal/oxide interface effects, such as build-in voltage, interface dipole,
+virtual oxide thinning, barrier deformation, etc. Therefore, it provides
+accurate band alignments. Calculations performed at an Al/amorphous-SiO2
+exhibit a good agreement between existing experiments and simulation data. We
+Also observed a space charge region at the interface resulting in non-linear
+band bending in the oxide, which virtually decreases its thickness, hence
+lowering the dielectric strength.",1704.06978v2
+2018-05-15,Measurement of the Oxidation state of Fe in the ISM using X-ray Absorption Spectroscopy,"The oxidation state of iron in the interstellar medium (ISM) can provide
+constraints on the processes that operated on material in the protosolar disk.
+We used synchrotron-based X-ray absorption spectra of several mineral standards
+and two kinds of primitive extraterrestrial materials to constrain the
+oxidation state and mineralogy of the host-phase of ISM Fe as measured by X-ray
+observations of Fe-L ISM absorption from the {\em Chandra X-ray Observatory}.
+Given the initial oxidation state of the building blocks of the Solar System,
+we explore nebular and parent-body processes that eventually led to the
+remarkable diversity of oxidation states of primitive Solar System materials.
+Oxidation of cometary material appears to have taken place in the nebula,
+before incorporation into cometary nuclei, although the mechanism is unknown.",1805.05921v1
+2008-07-22,Stress Development and Impurity Segregation during Oxidation of the Si(100) Surface,"We have studied the segregation of P and B impurities during oxidation of the
+Si(100) surface by means of combined static and dynamical first-principles
+simulations based on density functional theory. In the bare surface, dopants
+segregate to chemically stable surface sites or to locally compressed
+subsurface sites. Surface oxidation is accompanied by development of tensile
+surface stress up to 2.9 N/m at a coverage of 1.5 monolayers of oxygen and by
+formation of oxidised Si species with charges increasing approximately linearly
+with the number of neighbouring oxygen atoms. Substitutional P and B defects
+are energetically unstable within the native oxide layer, and are
+preferentially located at or beneath the Si/SiOx interface. Consistently,
+first-principles molecular dynamics simulations of native oxide formation on
+doped surfaces reveal that dopants avoid the formation of P-O and B-O bonds,
+suggesting a surface oxidation mechanism whereby impurities remain trapped at
+the Si/SiOx interface. This seems to preclude a direct influence of impurities
+on the surface electrostatics and, hence, on the interactions with an external
+environment.",0807.3426v1
+2009-12-08,The Deposition of High-Quality HfO2 on Graphene and the Effect of Remote Oxide Phonon Scattering,"We demonstrate the atomic layer deposition of high-quality HfO2 film on
+graphene and report the magnitude of remote oxide phonon (ROP) scattering in
+dual-oxide graphene transistors. Top gates with 30 nm HfO2 oxide layer exhibit
+excellent doping capacity of greater than 1.5x10^(13)/cm^(2). The carrier
+mobility in HfO2-covered graphene reaches 20,000 cm^(2)/Vs at low temperature,
+which is the highest among oxide-covered graphene and compares to that of
+pristine samples. The temperature-dependent resistivity exhibits the effect of
+ROP scattering from both the SiO2 substrate and the HfO2 over-layer. At room
+temperature, surface phonon modes of the HfO2 film centered at 54 meV dominate
+and limit the carrier mobility to ~20,000 cm^(2)/Vs. Our results highlight the
+important choice of oxide in graphene devices.",0912.1378v2
+2012-01-04,Zinc in a +III oxidation state,"The possibility of Group 12 elements, such as Zn, Cd, and Hg existing in an
+oxidation state of +III or higher and hence transforming them into transition
+metals has fascinated chemists for decades. It took nearly 20 years before
+experiment could confirm the theoretical prediction that Hg indeed can exist in
+an oxidation state of +IV. While this unusual property of Hg is attributed to
+the relativistic effects, Zn being much lighter than Hg has not been expected
+to have an oxidation state higher than +II. Using density functional theory we
+show that an oxidation state of +III for Zn can be realized by choosing
+specific ligands with large electron affinities. We demonstrate this by a
+systematic study of the interaction of Zn with F, BO2, and AuF6 ligands whose
+electron affinities are progressively higher, namely, 3.4 eV, 4.5 eV, and 8.6
+eV, respectively. Discovery of higher oxidation states of elements can help in
+the formulation of new reactions and hence in the development of new chemistry.",1201.1014v1
+2012-01-23,Effect of oxidation on the Mechanical Properties of Liquid Gallium and Eutectic Gallium-Indium,"Liquid metals exhibit remarkable mechanical properties, in particular large
+surface tension and low viscosity. However, these properties are greatly
+affected by oxidation when exposed to air. We measure the viscosity, surface
+tension, and contact angle of gallium (Ga) and a eutectic gallium-indium alloy
+(eGaIn) while controlling such oxidation by surrounding the metal with an acid
+bath of variable concentration. Rheometry measurements reveal a yield stress
+directly attributable to an oxide skin that obscures the intrinsic behavior of
+the liquid metals. We demonstrate how the intrinsic viscosity can be obtained
+with precision through a scaling technique that collapses low- and
+high-Reynolds number data. Measuring surface tension with a pendant drop
+method, we show that the oxide skin generates a surface stress that mimics
+surface tension and develop a simple model to relate this to the yield stress
+obtained from rheometry. We find that yield stress, surface tension, and
+contact angle all transition from solid-like to liquid behavior at the same
+critical acid concentration, thereby quantitatively confirming that the
+wettability of these liquid metals is due to the oxide skin.",1201.4828v1
+2015-12-06,"Anisotropy, band-to-band transitions, phonon modes, and oxidation properties of cobalt-oxide core-shell slanted columnar thin films","Highly-ordered and spatially-coherent cobalt slanted columnar thin films were
+deposited by glancing angle deposition onto silicon substrates, and
+subsequently oxidized by annealing at 475 $^{\circ}$C. Scanning electron
+microscopy, Raman scattering, generalized ellipsometry, and density functional
+theory investigations reveal shape-invariant transformation of the slanted
+nanocolumns from metallic to transparent metal-oxide core-shell structures with
+properties characteristic of spinel cobalt oxide. We find passivation of
+Co-SCTFs yielding CoAl$_2$O$_3$ core-shell structures produced by conformal
+deposition of a few nanometers of alumina using atomic layer deposition fully
+prevents cobalt oxidation in ambient and from annealing up to 475 $^{\circ}$C.",1512.01860v1
+2016-12-12,Revisiting Graphene Oxide Chemistry via Spatially-Resolved Electron Energy Loss Spectroscopy,"The type and distribution of oxygen functional groups in graphene oxide (GO)
+and reduced graphene oxide (RGO) remain still a subject of great debate. Local
+analytic techniques are required to access the chemistry of these materials at
+a nanometric scale. Electron energy loss spectroscopy in a scanning
+transmission electron microscope can provide the suitable resolution, but GO
+and RGO are extremely sensitive to electron irradiation. In this work we employ
+a dedicated experimental setup to reduce electron illumination below damage
+limit. GO oxygen maps obtained at a few nanometers scale show separated domains
+with different oxidation levels. The C/O ratio varies from about 4:1 to 1:1,
+the latter corresponding to a complete functionalization of the graphene
+flakes. In RGO the residual oxygen concentrates mostly in regions few tens
+nanometers wide. Specific energy-loss near-edge structures are observed for
+different oxidation levels. By combining these findings with first-principles
+simulations we propose a model for the highly oxidized domains where graphene
+is fully functionalized by hydroxyl groups forming a 2D-sp$^3$ carbon network
+analogous to that of graphane.",1612.03594v1
+2016-12-19,Three-dimensional patterning of solid microstructures through laser reduction of colloidal graphene oxide in liquid-crystalline dispersions,"Graphene materials and structures have become an essential part of modern
+electronics and photovoltaics. However, despite many production methods,
+applications of graphene-based structures are hindered by high costs, lack of
+scalability and limitations in spatial patterning. Here we fabricate
+three-dimensional functional solid microstructures of reduced graphene oxide in
+a lyotropic nematic liquid crystal of graphene oxide flakes using a pulsed
+near-infrared laser. This reliable, scalable approach is mask-free, does not
+require special chemical reduction agents, and can be implemented at ambient
+conditions starting from aqueous graphene oxide flakes. Orientational ordering
+of graphene oxide flakes in self-assembled liquid-crystalline phases enables
+laser patterning of complex, three-dimensional reduced graphene oxide
+structures and colloidal particles, such as trefoil knots, with ""frozen""
+orientational order of flakes. These structures and particles are mechanically
+rigid and range from hundreds of nanometres to millimetres in size, as needed
+for applications in colloids, electronics, photonics and display technology.",1612.06030v1
+2019-06-05,Inverted Perovskite Photovoltaics using Flame Spray Pyrolysis Solution based CuAlO2/Cu-O Hole Selective Contact,"We present the functionalization process of a conductive and transparent
+copper aluminum oxide, copper oxide alloy. The copper aluminum oxide, copper
+oxide powders were developed by flame spray pyrolysis and their stabilized
+dispersions were treated by sonication and centrifugation methods. We show that
+when the supernatant part of the treated copper aluminum oxide, copper oxide
+dispersions is used for the development of hole transporting layers the
+corresponding inverted perovskite solar cells show improved functionality and
+power conversion efficiency with negligible hysteresis effect.",1906.01989v1
+2019-07-25,Stainless Steel Surface Structure and Initial Oxidation at Nanometric and Atomic Scales,"The durability of passivable metals and alloys is often limited by the
+stability of the surface oxide film, the passive film, providing
+self-protection against corrosion in aggressive environments. Improving this
+stability requires to develop a deeper understanding of the surface structure
+and initial surface reactivity at the nanometric or atomic scale. In this work
+we applied scanning tunneling microscopy to unravel the surface structure of a
+model stainless steel surface in the metallic state and its local modifications
+induced by initial reaction in dioxygen gas. The results show a rich and
+complex structure of the oxide-free surface with reconstructed atomic lattice
+and self-organized lines of surface vacancies at equilibrium. New insight is
+brought into the mechanisms of initial oxidation at steps and vacancy injection
+on terraces leading to Cr-rich oxide nuclei and locally Cr-depleted terraces,
+impacting the subsequent mechanism of chromium enrichment essential to the
+stability of the surface oxide.",1907.10911v1
+2019-10-19,Wafer-size VO2 film prepared by water-vapor oxidant,"The growth of wafer-scale and uniform monoclinic VO2 film was a challenge if
+considering the multivalent vanadium atom and the various phase structures of
+VO2 compound. Directly oxidizing metallic vanadium film in oxygen gas seemed to
+be an easy way, while the oxidation parameters were extremely sensitive due to
+the critical preparation window. Here we proposed a facile thermal oxidation by
+water-vapor to produce wafer-scale VO2 films with high quality. Results
+indicated that by using the water-vapor oxidant, the temperature window for VO2
+growth was greatly broadened. In addition, the obtained wafer-size VO2 film
+showed very uniform surface and sharp resistance change. The chemical reaction
+routes with water-vapor were calculated, which favored the VO2 film growth. Our
+results not only demonstrated that the water-vapor could be used as a modest
+oxidizing agent, but also showed the unique advantage for large size VO2 film
+preparation.",1910.08776v3
+2020-01-05,Two-section reactor model for autothermal reforming of methane to synthesis gas,"A one-dimensional and stationary reactor model is presented to describe the
+catalytic conversion of a gaseous hydrocarbon fuel with air and steam to
+synthesis gas by autothermal reforming (ATR) and catalytic partial oxidation
+(CPO). The model defines two subsequent sections in the reactor, namely an
+upstream oxidation section, and a downstream reforming section. In the
+oxidation section all of the oxygen is converted, with partial conversion of
+the fuel. An empirical fuel utilization ratio is used to quantify which part of
+the fuel is converted in the oxidation section as function of the relative
+flows of air and steam. In the oxidation section, the gas temperature rapidly
+increases toward the toptemperature at the intersection with the reforming
+section. In this section the temperature decreases while the fuel is further
+converted with water and CO2 as oxidant. For methane as fuel, simulation
+results are presented and compared with experiments. For multicomponent fuels
+such as natural gas and naphtha, it is described how the two-section model can
+be applied.",2001.01282v1
+2020-01-08,Novel hypostasis of old materials in oxide electronics: metal oxides for resistive random access memory applications,"Transition-metal oxide films, demonstrating the effects of both threshold and
+nonvolatile memory resistive switching, have been recently proposed as
+candidate materials for storage-class memory. In this work we describe some
+experimental results on threshold switching in a number of various transition
+metal (V, Ti, Fe, Nb, Mo, W, Hf, Zr, Mn, Y, and Ta) oxide films obtained by
+anodic oxidation. Then, the results concerning the effects of bistable
+resistive switching in MOM and MOS structures on the basis of such oxides as
+V2O5, Nb2O5, and NiO are presented. It is shown that sandwich structures on the
+basis of the Au/V2O5/SiO2/Si, Nb/Nb2O5/Au, and Pt/NiO/Pt can be used as memory
+elements for ReRAM applications. Finally, model approximations are developed in
+order to describe theoretically the effect of nonvolatile unipolar switching in
+Pt NiO-Pt structures.",2001.03026v1
+2020-12-12,Single-Phase Duodenary High-Entropy Fluorite/Pyrochlore Oxides with an Order-Disorder Transition,"Improved thermomechanical properties have been reported for various
+high-entropy oxides containing typically five metal cations. This study further
+investigates a series of duodenary (11 metals + oxygen) high-entropy oxides by
+mixing different fractions of a five-cation fluorite-structured niobate and a
+seven-cation pyrochlore (both containing Yb) with matching lattice constants.
+Nine compositions of duodenary high-entropy oxides have been examined. All of
+them exhibit single high-entropy phases of either disordered fluorite or
+ordered pyrochlore structure. An order-disorder transition (ODT) is evident
+with changing composition, accompanied by a reduction in thermal conductivity
+(k). In comparison with the ODT criteria developed from ternary oxides, these
+duodenary oxides are more prone to disorder, but the ODT is still controlled by
+similar factors (but at different thresholds). Interestingly, there are abrupt
+increases in Young's modulus (E) at low mixing concentrations near both
+endmembers. The E/k ratios are increased, in comparison with both endmembers.
+This study suggests a new route to tailor high-entropy ceramics via controlling
+cation ordering vs. disordering.",2012.12866v1
+2017-11-20,Atomic and electronic structures of stable linear carbon chains on Ag-nanoparticles,"In this work, we report X-ray photoelectron (XPS) and valence band (VB)
+spectroscopy measurements of surfactant-free silver nanoparticles and
+silver/linear carbon chains (Ag@LCC) structures prepared by pulse laser
+ablation (PLA) in water. Our measurements demonstrate significant oxidation
+only on the surfaces of the silver nanoparticles with many covalent
+carbon-silver bonds but only negligible traces of carbon-oxygen bonds.
+Theoretical modeling also provides evidence of the formation of robust
+carbon-silver bonds between linear carbon chains and pure and partially
+oxidized silver surfaces. A comparison of theoretical and experimental
+electronic structures also provides evidence of the presence of non-oxidized
+linear carbon chains on silver surfaces. To evaluate the chemical stability, we
+investigated the energetics of the physical adsorption of oxidative species
+(water and oxygen) and found that this adsorption is much preferrable on
+oxidized or pristine silver surfaces than the adsorption of linear carbon
+chains, which makes the initial step in the oxidation of LCC energetically
+unfavorable.",1711.07119v1
+2019-04-08,Probing the correlation between phase evolution and growth kinetics in the oxide layers of tungsten using Raman spectroscopy and EBSD,"Tungsten, a plasma-facing material for future fusion reactors, may be exposed
+to air during abnormal operation or accidents. Only limited information is
+available on the evolution of related oxide phases. This work addresses the
+effect of substrate orientation on structural variations of tungsten oxides.
+Annealing experiments in an argon-oxygen atmosphere have been conducted at T =
+400 {\deg}C under varying oxygen partial pressure and oxidation time. A
+combination of EBSD, Raman spectroscopy and confocal microscopy shows
+preferential oxidation initially on {111} base material planes. The oxide scale
+changes its phase composition dynamically, influencing the kinetics of its
+growth.",1904.04392v2
+2020-08-10,Interface-Confined Doubly Anisotropic Oxidation of Two-Dimensional MoS2,"Despite their importance, chemical reactions confined in a low dimensional
+space are elusive and experimentally intractable. In this work, we report
+doubly anisotropic, in-plane and out-of-plane, oxidation reactions of
+two-dimensional crystals, by resolving interface-confined thermal oxidation of
+a single and multilayer MoS2 supported on silica substrates from their
+conventional surface reaction. Using optical second-harmonic generation
+spectroscopy of artificially stacked multilayers, we directly proved that
+crystallographically oriented triangular oxides (TOs) were formed in the
+bottommost layer while triangular etch pits (TEs) were generated in the topmost
+layer and that both structures were terminated with zigzag edges. The formation
+of the Mo oxide layer at the interface demonstrates that O2 diffuses
+efficiently through the van der Waals (vdW) gap but not MoO3, which would
+otherwise sublime. The fact that TOs are several times larger than TEs
+indicates that oxidation is greatly enhanced when MoS2 is in direct contact
+with silica substrates, which suggests a catalytic effect. This study indicates
+that the vdW-bonded interfaces are essentially open to mass transport and can
+serve as a model system for investigating chemistry in low dimensional spaces.",2008.03933v1
+2020-10-14,Trends of epitaxial perovskite oxide films catalyzing the oxygen evolution reaction in alkaline media,"The oxygen evolution reaction (OER) is considered a key reaction for
+electrochemical energy conversion but slow kinetics hamper application in
+electrolyzers, metal-air batteries and other applications that rely on
+sustainable protons from water oxidation. In this review, the prospect of
+epitaxial perovskite oxides for the OER at room temperature in alkaline media
+is reviewed with respect to fundamental insight into systematic trends of the
+activity. First, we thoroughly define the perovskite structure and its
+parameter space. Then, the synthesis methods used to make electrocatalytic
+epitaxial perovskite oxide are surveyed, and we classify the different kinds of
+electrodes that can be assembled for electrocatalytic investigations. We
+discuss the semiconductor physics of epitaxial perovskite electrodes and their
+consequences for the interpretation of catalytic results. Prototypical
+mechanisms of the OER are introduced and comparatively discussed. OER
+investigations on epitaxial perovskite oxides are comprehensively surveyed and
+selected trends are graphically highlighted. The review concludes with a short
+perspective on opportunities for future electrocatalytic research on epitaxial
+perovskite oxide systems.",2010.06860v1
+2020-11-17,Synthetically Encapsulated \& Self-Organized Transition Metal Oxide Nano Structures inside Carbon Nanotubes as Robust Li-ion Battery Anode Materials,"We report a comprehensive study on the electrochemical performance of four
+different Transition Metal Oxides encapsulated inside carbon nanotubes (CNT).
+Irrespective of the type of oxide-encapsulate, all these samples exhibit
+superior cyclic stability as compared to the bare-oxide. Innovative use of
+camphor during sample synthesis enables precise control over the morphology of
+these self-organized carbon nanotube structures, which in turn appears to play
+a crucial role in the magnitude of the specific capacity. A comparative
+evaluation of the electrochemical data on different samples bring forward
+interesting inferences pertaining to the morphology, filling fraction of the
+oxide-encapsulate, and the presence of oxide nano-particles adhering outside
+the filled CNT. Our results provides useful pointers towards the optimization
+of critical parameters, thus paving the way for using these synthetically
+encapsulated and self-organized carbon nanotube structures as anode materials
+for Li-ion batteries, and possibly other electrochemical applications.",2011.08619v1
+2020-11-17,Effect of Surface Roughness on Early Stage Oxidation Behavior of Ni-Base Superalloy IN 625,"In the present work the effect of surface roughness on oxidation behavior
+during the early stages of high temperature exposure of Ni-base superalloy IN
+625 is described. The surface roughness was described using standard contact
+profilometer as well as novel method, fractal analysis. It was found that the
+different surface preparation resulted in a difference in roughness with a
+parameter increase of at least one order of magnitude for the ground sample as
+compared with the polished sample. The oxidation test was performed in a
+horizontal tube furnace. Post exposure analyses including glow discharge
+optical emission spectrometry (GD OES) and scanning electron microscopy (SEM),
+which revealed that grinding lowers the oxidation kinetics of IN 625. It was
+found that surface preparation influences the oxide scale composition and
+morphology. The hypothesis explaining the mechanism responsible for the changes
+in oxidation behavior is proposed as well.",2011.08931v1
+2020-11-21,Fabrication of zinc oxide/graphene-carbon nanotubes nanocomposite with enhanced dye degradation ability,"A comparative study between zinc oxide graphene-carbon nanotubes
+nanocomposite and ZnO nanoparticles was carried out to investigate their
+abilities in the degradation of Rhodamine B dye. We utilized the Modified
+Hummer method to prepare the graphene oxide nanosheet. Moreover,
+graphene-carbon nanotubes had been synthesized from GO and multi-walled carbon
+nanotubes with a hydroxyl group. The hydrothermal method was employed to
+fabricate the zinc oxide graphene-carbon nanotubes nanocomposite from ZnO
+nanoparticles and graphene-carbon nanotubes. During the characterization by
+X-ray Diffraction (XRD), all the significant peaks of ZnO and zinc oxide
+graphene-carbon nanotubes nanocomposite were found in the same phase angle. In
+addition, the final nanocomposite was also characterized by Field Emission
+Scanning Electron Microscope (FESEM) and Energy Dispersive X-ray Spectroscopy
+(EDS). Finally, from the dye degradation test, it was apparent that zinc oxide
+graphene-carbon nanotubes nanocomposite showed superior dye removal ability
+compared to the ZnO nanoparticles.",2011.10841v2
+2021-05-12,Iron-silica interaction during reduction of precipitated silica-promoted iron oxides using in situ XRD and TEM,"The effect of silica-promotion on the reduction of iron oxides in hydrogen
+was investigated using in situ X-ray diffraction and aberration-corrected
+transmission electron microscopy to understand the mechanism of reduction and
+the identity of the iron(II) silicate phase that has historically been
+designated as the cause of the iron-silica interaction in such materials. In
+the absence of a silica promoter the reduction of hematite to {\alpha}-Fe
+proceeds via magnetite. Silica promoted amorphous iron oxide is reduced to
+{\alpha}-Fe via stable magnetite and w\""ustite phases. During reduction of
+silica-promoted iron oxide, Fe0 diffuses out of the amorphous silica-promoted
+iron oxide matrix upon reduction from Fe2+ and coexists with an amorphous
+Fe-O-Si matrix. Certain portions of w\""ustite remain difficult to reduce to
+{\alpha}-Fe owing to the formation of a protective silica-containing layer
+covering the remaining iron oxide regions. Given sufficient energy, this
+amorphous Fe-O-Si material forms ordered, crystalline fayalite.",2105.05620v1
+2021-12-11,Elucidating the Influence of Native Defects on Electrical and Optical Properties in Semiconducting Oxides: An Experimental and Theoretical Investigation,"Defect engineering using self-doping or creating vacancies in polycrystalline
+oxide based materials has profound influence on optical absorption, UV photo
+detection, and electrical switching. However, defects induced semiconducting
+oxide devices show enhancement in photo detection and photosensitivity, and
+hence still remain interesting in the field of optoelectronics. In this study,
+defect engineering in semiconducting oxide materials is discussed along with
+their roles in optoelectronic device-based applications. Theoretical
+investigations have been done for identifying defect states by performing
+first-principles electronic structure calculations, employing the
+density-functional theory. Particularly, in this work, we have focused on
+probing the defect-induced changes in optical and electrical processes by means
+of experimental as well as computational investigations. Hence, systematic
+experimental measurements of optical absorption, electrical switching, charge
+density, and photocurrent in defect-rich semiconducting oxide samples have been
+performed. Our results suggest that defects can lead to enhancement of
+optoelectronic properties such as photocurrent, switching speed, optical
+absorption, etc. for semiconducting oxide based devices.",2112.05926v1
+2022-04-11,On the fluctuation-dissipation of the oxide trapped charge in a MOSFET operated down to deep cryogenic temperatures,"An analysis of the oxide trapped charge noise in a MOSFET operated down to
+deep cryogenic temperatures is proposed. To this end, a revisited derivation of
+the interface trap conductance Gp and oxide trapped charge noise SQt at the
+SiO2/Si MOS interface is conducted under very low temperature condition, where
+Fermi-Dirac statistics applies. A new relation between the oxide trapped charge
+noise SQt and the interface trap conductance Gp is established, showing the
+inadequacy of the Nyquist relation at very low temperature. Finally, a new
+formula for the oxide trapped charge 1/f noise, going beyond the classical
+Boltzmann expression, is developed in terms of oxide trap density and effective
+temperature accounting for degenerate statistics.",2204.04958v2
+2023-03-20,Oxide spinels with superior Mg conductivity,"Mg batteries with oxide cathodes have the potential to significantly surpass
+existing Li-ion technologies in terms of sustainability, abundance, and energy
+density. However, Mg intercalation at the cathode is often severely hampered by
+the sluggish kinetics of Mg$^{2+}$ migration within oxides. Here we report a
+combined theoretical and experimental study addressing routes to identify
+cathode materials with an improved Mg-ion mobility. Using periodic density
+functional theory calculations, Mg$^{2+}$ migration in oxide spinels has been
+studied, revealing key features that influence the activation energy for
+Mg$^{2+}$ migration. Furthermore, the electronic and geometrical properties of
+the oxide spinels as well as their stability have been analyzed for a series of
+different transition metals in the spinels. We find that electronegative
+transition metals enable a high Mg-ion mobility in the oxide spinel frameworks
+and thus a favorable cathode functionality. Based on the theoretical findings,
+some promising candidates have been identified, prepared and structurally
+characterized. Our combined theoretical and experimental findings open up an
+avenue toward the utilization of functional cathode materials with improved
+Mg$^{2+}$ transport properties for Mg-metal batteries.",2303.11122v1
+2023-04-26,Elucidating the active phases of CoOx films on Au(111) in the CO Oxidation Reaction,"Using CoOx thin films supported on Au(111) single crystal surfaces as model
+catalysts for the CO oxidation reaction we show that three reaction regimes
+exist in response to chemical and topographic restructuring of the CoOx
+catalyst as a function of reactant gas phase CO/O2 stoichiometry a finding that
+highlights the versatility of catalysts and their evolution in response to
+reaction conditions. Under oxygen-lean conditions and moderate temperatures
+(below 150C degrees) partially oxidized films containing CoO were found to be
+efficient catalysts. In contrast, stoichiometric CoO films containing only Co2+
+form carbonates in the presence of CO that poison the reaction below 300 C
+degrees. Under oxygen-rich conditions a more oxidized catalyst phase forms
+containing Co3+ species that is effective in a wide temperature range. Resonant
+photoemission spectroscopy (ResPES) revealed the unique role of Co3+ sites in
+catalyzing the CO oxidation. DFT calculations provided deeper insights into the
+pathway and free energy barriers for the reactions on these oxide phases.",2304.13859v1
+2023-05-02,"Data-Driven, Physics-Informed Descriptors of Cation Ordering in Multicomponent Oxides","The structural tunability and compositional diversity of multicomponent
+perovskite oxides have enabled their various applications, including catalysis
+and electronics. The cation ordering in these oxides, ranging from disordered
+(i.e., high-entropy) to ordered (e.g., rocksalt), profoundly influences their
+properties. While computational design tools can typically predict properties
+associated with a particular ordering, inferring which ordering -- if any --
+will be observed in synthesized oxides remains challenging. Here, we leveraged
+first-principles simulations and machine learning to develop data-driven,
+physics-informed descriptors of experimental ordering in multicomponent
+perovskites and compared them with traditional physicochemical descriptors,
+e.g., ionic radii and oxidation states. The fitted low-dimensional
+classification models correctly rank up to 93% of compositions in an
+experimental dataset of 190 perovskites between cation-ordered and disordered,
+offering a rigorous benchmark between theory and experiments. Furthermore,
+these descriptors accelerate high-throughput virtual screening of
+multicomponent oxides by predicting their dominant ordering to avoid costly,
+exhaustive simulations of cation arrangements.",2305.01806v1
+2023-05-11,Interfacial two-dimensional oxide enhances photocatalytic activity of graphene/titania via electronic structure modification,"A two-dimensional layer of oxide reveals itself as a essential element to
+drive the photocatalytic activity in a nanostructured hybrid material, which
+combines high-quality epitaxial graphene and titanium dioxide nanoparticles. In
+particular, it has been revealed that the addition of a 2D Ti oxide layer
+sandwiched between graphene and metal induces a p-doping of graphene and a
+consistent shift in the Ti d states. These modifications induced by the
+interfacial oxide layer induce a reduction of the probability of charge carrier
+recombination and enhance the photocatalytic activity of the heterostructure.
+This is indicative of a capital role played by thin oxide films in fine-tuning
+the properties of heterostructures based on graphene and pave the way to new
+combinations of graphene/oxides for photocatalysis-oriented applications.",2305.06708v1
+2023-07-19,Oxide layer dependent orbital torque efficiency in ferromagnet/Cu/Oxide heterostructures,"The utilization of orbital transport provides a versatile and efficient spin
+manipulation mechanism. As interest in orbital-mediated spin manipulation
+grows, we face a new issue to identify the underlying physics that determines
+the efficiency of orbital torque (OT). In this study, we systematically
+investigate the variation of OT governed by orbital Rashba-Edelstein effect at
+the Cu/Oxide interface, as we change the Oxide material. We find that OT varies
+by a factor of ~2, depending on the Oxide. Our results suggest that the active
+electronic interatomic interaction (hopping) between Cu and oxygen atom is
+critical in determining OT. This also gives us an idea of what type of material
+factors is critical in forming a chiral orbital Rashba texture at the Cu/Oxide
+interface.",2307.09824v1
+2023-08-07,Modeling of electrochemical oxide film growth -- impact of band-to-band tunneling,"The Point Defect Model (PDM) describes the corrosion resistance properties of
+oxide films based on interfacial reactions and defect transport, which are
+affected by the electric field inside the oxide film. The PDM assumes a
+constant electric field strength due to band-to-band tunneling (BTBT) of
+electrons and the separation of electrons and holes by high electric fields. In
+this manuscript we present a more complex expansion of the common models to
+simulate steady state oxide films to test this assumption. The R-PDM was
+extended by including the transport of electrons and holes and BTBT. It could
+be shown that BTBT only occurs in very rare cases of narrow band gaps and high
+electric fields and the impact of electrons and holes does indeed lead to a
+buffering effect on the electric field, but does not lead to a constant
+electric field strength. Modeling the transport of electrons and holes on the
+oxide film allows to specifically estimate their potential impact on the film
+growth. Especially during modeling of oxide films with narrow band gap and/or
+electrochemical reactions at the film/solution interface the electrons and
+holes needs to be included to the model.",2308.05113v1
+2023-08-24,Modeling for heterogeneous oxidative aging of polymers using coarse-grained molecular dynamics,"This study presents a coarse-grained molecular dynamics simulation model to
+investigate the process of oxidative aging in polymers. The chemical aging
+effect is attributed to the auto-oxidation mechanism, which is initiated by
+radicals, leading to the chain scission and crosslinking of polymer chains. In
+this study, we integrate a thermal oxidation kinetic model in the oxygen excess
+regime into the Kremer-Grest model, thereby enabling a reactive coarse-grained
+molecular dynamics simulation to capture the process of oxidative degradation.
+Our simulation reveals that when the timescale of the characteristic reaction
+step of oxidative degradation is shorter than the longest relaxation time of
+polymer chains, the scission sites exhibit spatial heterogeneity. This
+innovative simulation model possesses the potential to enhance our
+comprehension of polymer aging phenomena, thus making noteworthy contributions
+to the realm of polymer science and degradation chemistry.",2308.12620v1
+2023-11-22,Mechanistic Insights into the Hydrazine-induced Chemical Reduction Pathway of Graphene Oxide,"Hydrazine stands out as the most generally used chemical-reducing agent for
+reducing graphene oxide. Despite numerous experimental and theoretical
+investigations into the reduction reaction, the reduction mechanism remains
+unclear. In this study, we propose that, in aqueous hydrazine solutions, both
+hydrazine and hydroxide ions could initiate the reduction of graphene oxide. We
+introduce a chemical reaction pathway involving C-H cleavage and a
+dehydroxylation process for the reduction of graphene oxide. By utilizing
+density functional theory calculations, the reduction reactions mediated by
+hydrazine and hydroxide ions are separately investigated. The reaction routes
+on the basal plane and edge regions of graphene oxide are discussed
+independently. The density functional theory calculations demonstrate that the
+proposed mechanism is both thermodynamically and dynamically feasible. This
+work might contribute to an atomic-level comprehension of a longstanding
+challenge in the field of graphene oxide.",2311.13086v1
+2024-02-06,High-temperature oxidation and nitridation of substoichiometric zirconium carbide in isothermal air,"The influence of nitrogen on the oxidation behavior of hot-pressed zirconium
+carbide was investigated using a flow-tube furnace at temperatures ranging from
+1000 to 1600 {\deg}C. Mass gain, oxide formation characteristics, and oxide
+transitions were evaluated at various experimental conditions. Differences in
+oxidation behavior across the range of temperatures investigated show both
+kinetic and microstructural dependence with implications pointing to this
+materials efficacy in ultra-high temperature applications. Results suggest that
+at temperatures above 1400 {\deg}C, although oxidation mechanisms remain
+dominant, nitridation and reduction mechanisms may be appreciable enough to
+require consideration. Supporting discussions regarding polymorphism and
+microstructural influences are outlined.",2402.04337v1
+1998-12-14,Estimation of the charge carrier localization length from Gaussian fluctuations in the magneto-thermopower of La_{0.6}Y_{0.1}Ca_{0.3}MnO_3,"The magneto-thermoelectric power (TEP) $\Delta S(T,H)$ of perovskite type
+manganise oxide $La_{0.6}Y_{0.1}Ca_{0.3}MnO_3$ is found to exhibit a sharp peak
+at some temperature $T^{*}=170K$. By approximating the true shape of the
+measured magneto-TEP in the vicinity of $T^{*}$ by a linear triangle of the
+form $\Delta S(T,H)\simeq S_p(H)\pm B^{\pm}(H)(T^{*}-T)$, we observe that $B
+^{-}(H)\simeq 2B ^{+}(H)$. We adopt the electron localization scenario and
+introduce a Ginzburg-Landau (GL) type theory which incorporates the two
+concurrent phase transitions, viz., the paramagnetic-ferromagnetic transition
+at the Curie point $T_C$ and the ""metal-insulator"" (M-I) transition at
+$T_{MI}$. The latter is characterized by the divergence of the field-dependent
+charge carrier localization length $\xi (T,H)$ at some characteristic field
+$H_0$. Calculating the average and fluctuation contributions to the total
+magnetization and the transport entropy related magneto-TEP $\Delta S(T,H)$
+within the GL theory, we obtain a simple relationship between $T^{*}$ and the
+above two critical temperatures ($T_{C}$ and $T_{MI}$). The observed slope
+ratio $B ^{-}(H)/B ^{+}(H)$ is found to be governed by the competition between
+the electron-spin exchange $JS$ and the induced magnetic energy $M_sH_0$. The
+comparison of our data with the model predictions produce $T_{C}=195K$,
+$JS=40meV$, $M_0=0.4M_s$, $\xi_0=10\AA$, and $n_e/n_i=2/3$ for the estimates of
+the Curie temperature, the exchange coupling constant, the critical
+magnetization, the localization length, and the free-to-localized carrier
+number density ratio, respectively.",9812219v1
+2013-07-28,Novel multiferroics with ferromagnetic phase induced in paraelectric antiferromagnets by electric field application,"The phase diagram of a quantum paraelectric antiferromagnet EuTiO3 under an
+external electric field was calculated using Landau-Ginzburg-Devonshire theory.
+It was shown that the application of an external electric field E leads to the
+appearance of a ferromagnetic phase due to the magnetoelectric coupling. In
+particular, electric field application decreases the transition temperature
+TAFM to antiferromagnetic (AFM) phase and induces ferromagnetic (FM) phase, so
+that at some E field larger than the critical field (Ecr), TFM becomes higher
+than TAFM and the FM phase appears. Note that Ecr increases and magnetization
+decreases as the temperature increases. The value of the critical field Ecr =
+0.40*10^6 V/cm we calculated appeared close to the value Ecr = 0.5*10^6 V/cm
+obtained recently by Ryan et al. with the help of density functional theory for
+EuTiO3 film under a compressive strain produced by substrate. At the fields E
+>0.83*10^6 V/cm, AFM disappears for all considered temperatures and so FM
+becomes the only stable magnetic phase. We find that ferromagnetic phase can be
+induced by an E-field in other paraelectric antiferromagnet oxides with a
+positive AFM-type magnetoelectric (ME) coupling coefficient and negative
+FM-type ME coupling coefficient. In particular, the critical E-field was
+estimated for another paraelectric antiferromagnet Sr0.7Ba0.3MnO3 as
+0.2x10^5V/cm at 0 K. Analysis of the dependence of magnetization and
+antimagnetization on the external electric field and the polarization induced
+by the field, which yields the magnetoelectric coupling, is reported. The
+results show the possibility to control multiferroicity, including the FM and
+AFM phases, with help of an electric field application.",1307.7402v1
+2015-10-08,Phonons and Stability of Infinite-Layer Iron Oxides SrFeO2 and CaFeO2,"We present detailed ab-initio lattice dynamical analysis of the Fe-O
+infinite-layer compounds CaFeO2 and SrFeO2 in various magnetic configurations.
+These indicate strong spin-phonon coupling in SrFeO2 in contrast to that in
+case of CaFeO2. Powder neutron inelastic scattering experiments on SrFeO2 have
+also been performed at temperatures from 5 K to 353 K in the antiferromagnetic
+phase and analyzed using the ab-initio calculations. These suggest distortion
+of the ideal infinite planer structure above 300 K. From our ab-initio
+calculations in SrFeO2 as a function of volume, we suggest that the distortion
+in SrFeO2 above 300 K is similar to that known in CaFeO2 at ambient conditions.
+The distortion of the planer structure of CaFeO2 involves doubling of the
+planer unit cell that may be usually expected to be due to a soft phonon mode
+at the M-point (1/2 1/2 0). However, our ab-initio calculations show quite
+unusually that all the M-point (1/2 1/2 0) phonons are stable, but two stable
+M3+ and M2-modes anharmonically couple with an unstable Bu mode at the zone
+centre and lead to the cell doubling and the distorted structure. Magnetic
+exchange interactions in both the compounds have been computed on the basis of
+the ideal planar structure (P4/mmm space group) and with increasing amplitude
+of the Bu phonon mode. These reveal that the magnetic exchange interactions
+reduce significantly with increasing distortion. We have extended the ab-initio
+phonon calculation to high pressures, which reveal that, above 20 GPa of
+pressure, the undistorted planer CaFeO2 becomes dynamically stable. We also
+report computed phonon spectra in SrFeO3 that has a cubic structure, which is
+useful to understand the role of the difference in geometry of oxygen atoms
+around the Fe atom with respect to planer SrFeO2.",1510.02294v1
+2016-06-14,Nickel-cobalt-titanate thin films - new sustainable magnetic oxides,"Single phase nickel-cobalt-titanate thin films with a formula A1+2xTi1-xO3,
+where A is Ni2+,Co2+ and -0.25<x<1, were grown by pulsed laser deposition on
+sapphire substrates. There is a large window in which both Ni/Co ratio and x
+can be chosen independently. In the prototype ilmenite and corundum structures
+one third of the octahedra are vacant. The reported structure is obtained by
+filling vacant (x>0) or emptying filled (x<0) octahedra. When x = 1 all
+octahedra are filled. Two factors controlling the magnetism and crystal
+distortion are identified. First is a direct overlap between the adjacent
+cation d-orbitals resulting in a bond formation and magnetic interactions
+between the cations. This is most clearly revealed as a crystal distortion in
+the x approximately 0 compositions with approximately equal amounts of Ni and
+Co: the distortion of the x approximately 0 compound is a function of Ni/Co
+ratio. The second factor is x, which controls the cation shift towards a vacant
+octahedron. The displacement decreases and the symmetry increases with
+decreasing Ti content as was revealed by x-ray diffraction and Raman
+spectroscopy. When all octahedra are filled the cations prefer octahedron
+center positions. Also the number density of cations has increased by a factor
+of 50 percent when compared to the ilmenite structure. The number density
+ratios of Ni/Co cations between x=1 and x=0 compounds is 3. The Raman and x-ray
+diffraction data collected on samples with x = 1 or close to 1 are interpreted
+in terms of P63/mmc space group.",1606.04256v3
+2020-07-17,"Crystalline and magnetic structures, magnetization, heat capacity and anisotropic magnetostriction effect in a yttrium-chromium oxide","We have studied a nearly stoichiometric insulating
+Y$_{0.97(2)}$Cr$_{0.98(2)}$O$_{3.00(2)}$ single crystal by performing
+measurements of magnetization, heat capacity, and neutron diffraction. Albeit
+that the YCrO$_3$ compound behaviors like a soft ferromagnet with a coersive
+force of $\sim$ 0.05 T, there exist strong antiferromagnetic (AFM) interactions
+between Cr$^{3+}$ spins due to a strongly negative paramagnetic Curie-Weiss
+temperature, i.e., -433.2(6) K. The coexistence of ferromagnetism and
+antiferromagnetism may indicate a canted AFM structure. The AFM phase
+transition occurs at $T_\textrm{N} =$ 141.5(1) K, which increases to
+$T_\textrm{N}$(5T) = 144.5(1) K at 5 T. Within the accuracy of the present
+neuron-diffraction studies, we determine a G-type AFM structure with a
+propagation vector \textbf{k} = (1 1 0) and Cr$^{3+}$ spin directions along the
+crystallographic \emph{c} axis of the orthorhombic structure with space group
+\emph{Pnma} below $T_\textrm{N}$. At 12 K, the refined moment size is 2.45(6)
+$\mu_\textrm{B}$, $\sim$ 82\% of the theoretical saturation value 3
+$\mu_\textrm{B}$. The Cr$^{3+}$ spin interactions are probably two-dimensional
+Ising like within the reciprocal (1 1 0) scattering plane. Below
+$T_\textrm{N}$, the lattice configuration (\emph{a}, \emph{b}, \emph{c}, and
+\emph{V}) deviates largely downward from the Gr$\ddot{\textrm{u}}$neisen law,
+displaying an anisotropic magnetostriction effect and a magnetoelastic effect.
+Especially, the sample contraction upon cooling is enhanced below the AFM
+transition temperature. There is evidence to suggest that the actual
+crystalline symmetry of YCrO$_3$ compound is probably lower than the currently
+assumed one. Additionally, we compared the $t_{2\textrm{g}}$ YCrO$_3$ and the
+$e_\textrm{g}$ La$_{7/8}$Sr$_{1/8}$MnO$_3$ single crystals for a further
+understanding of the reason for the possible symmetry lowering.",2007.08985v2
+2016-11-16,Quantized Ballistic Transport of Electrons and Electron Pairs in LaAlO$_3$/SrTiO$_3$ Nanowires,"SrTiO$_3$-based heterointerfaces support quasi-two-dimensional (2D) electron
+systems that are analogous to III-V semiconductor heterostructures, but also
+possess superconducting, magnetic, spintronic, ferroelectric, and ferroelastic
+degrees of freedom. Despite these rich properties, the relatively low
+mobilities of 2D complex-oxide interfaces appear to preclude ballistic
+transport in 1D. Here we show that the 2D LaAlO$_3$/SrTiO$_3$ interface can
+support quantized ballistic transport of electrons and (non-superconducting)
+electron pairs within quasi-1D structures that are created using a
+well-established conductive atomic-force microscope (c-AFM) lithography
+technique. The nature of transport ranges from truly single-mode (1D) to
+three-dimensional (3D), depending on the applied magnetic field and gate
+voltage. Quantization of the lowest $e^2/h$ plateau indicate a ballistic
+mean-free path $l_{MF}\sim$ 20 $\mu$m, more than two orders of magnitude larger
+than for 2D LaAlO$_3$/SrTiO$_3$ heterostructures. Non-superconducting electron
+pairs are found to be stable in magnetic fields as high as $B=11$ T, and
+propagate ballistically with conductance quantized at 2$e^2/h$. Theories of
+one-dimensional (1D) transport of interacting electron systems depend crucially
+on the sign of the electron-electron interaction, which may help explain the
+highly ballistic transport behavior. The 1D geometry yields new insights into
+the electronic structure of the LaAlO$_3$/SrTiO$_3$ system and offers a new
+platform for the study of strongly interacting 1D electronic systems.",1611.05127v4
+2016-05-26,Evaluating the paleomagnetic potential of single zircon crystals using the Bishop Tuff,"Zircon crystals offer a unique combination of suitability for high-precision
+radiometric dating and high resistance to alteration. Paleomagnetic experiments
+on ancient zircons may potentially constrain the earliest geodynamo, which
+holds broad implications for the early Earth interior and atmosphere. However,
+the ability of zircons to record accurately the geomagnetic field has not been
+fully demonstrated. Here we conduct thermal and room temperature alternating
+field (AF) paleointensity experiments on 767.1 thousand year old (ka) zircons
+from the Bishop Tuff, California. The rapid emplacement of these zircons in a
+well-characterized magnetic field provides a high-fidelity test of the zircons
+intrinsic paleomagnetic recording accuracy. Successful dual heating experiments
+on nine zircons measured using a superconducting quantum interference device
+(SQUID) microscope yield a mean paleointensity of 46.2 +/- 18.8 microtesla
+(1sigma), which agrees closely with high-precision results from Bishop Tuff
+whole rock (43.0 +/- 3.2 microtesla). High-resolution quantum diamond magnetic
+mapping, electron microscopy, and X-ray tomography indicate that the bulk of
+the remanent magnetization in Bishop Tuff zircons is carried by Fe oxides
+associated with apatite inclusions, which would be susceptible to destruction
+via metamorphism and aqueous alteration in older zircons. As such, while
+zircons can reliably record the geomagnetic field, robust zircon-derived
+paleomagnetic results require careful characterization of the ferromagnetic
+carrier and demonstration of their occurrence in primary inclusions. We further
+conclude that a combination of quantum diamond magnetometry and high-resolution
+imaging can provide detailed, direct characterization of the ferromagnetic
+mineralogy of geological samples.",1605.08479v1
+2018-07-27,Controlling spin-orbit interactions in silicon quantum dots using magnetic field direction,"Silicon quantum dots are considered an excellent platform for spin qubits,
+partly due to their weak spin-orbit interaction. However, the sharp interfaces
+in the heterostructures induce a small but significant spin-orbit interaction
+which degrade the performance of the qubits or, when understood and controlled,
+could be used as a powerful resource. To understand how to control this
+interaction we build a detailed profile of the spin-orbit interaction of a
+silicon metal-oxide-semiconductor double quantum dot system. We probe the
+derivative of the Stark shift, $g$-factor and $g$-factor difference for two
+single-electron quantum dot qubits as a function of external magnetic field and
+find that they are dominated by spin-orbit interactions originating from the
+vector potential, consistent with recent theoretical predictions. Conversely,
+by populating the double dot with two electrons we probe the mixing of singlet
+and spin-polarized triplet states during electron tunneling, which we conclude
+is dominated by momentum-term spin-orbit interactions that varies from 1.85 MHz
+up to 27.5 MHz depending on the magnetic field orientation. Finally, we exploit
+the tunability of the derivative of the Stark shift of one of the dots to
+reduce its sensitivity to electric noise and observe an 80 % increase in
+$T_2^*$. We conclude that the tuning of the spin-orbit interaction will be
+crucial for scalable quantum computing in silicon and that the optimal setting
+will depend on the exact mode of qubit operations used.",1807.10415v4
+2021-02-12,"Oxygen magnetic polarization, nodes in spin density, and zigzag spin order in oxides","Recent DFT calculations for Ba2CoO4 (BCO) and neutron scattering experiments
+for SrRuO3 (SRO) have shown that oxygen develops a magnetic polarization.
+Moreover, DFT calculations for these compounds also unveiled unexpected nodes
+in the spin density, both along Co-O and Ru-O. For BCO, the overall
+antiferromagnetic state in its triangular lattice contains unusual zigzag spin
+patterns. Here, using simple model calculations supplemented by DFT we explain
+and extend these results. We predict that ligands that in principle should be
+spinless, such as O$^{2-}$, will develop a net polarization when they act as
+electronic bridges between transition metal (TM) spins ferromagnetically
+ordered, regardless of the number of intermediate ligand atoms. The reason is
+the hybridization between atoms and mobility of the electrons with spins
+opposite to those of the closest TM atoms. Moreover, for bonds with TMs
+antiferromagnetically ordered, counterintuitively our calculations show that
+oxygens should also have a net magnetization for the super-super-exchange cases
+TM-O-O-TM while for only one oxygen, as in Cu-O-Cu, the O-polarization should
+cancel. Our simple model also allows us to explain the presence of nodes based
+on the antibonding character of the dominant singly occupied molecular orbitals
+along the TM-O bonds. Finally, the zigzag pattern order becomes the ground
+state mainly due to the influence of the Hubbard $U$, that creates the moments,
+in combination with a robust easy-axis anisotropy that suppresses the competing
+120$^{\circ}$ degree antiferromagnetic order of a triangular lattice. Our
+predictions are generic and should be applicable to any other compound with
+characteristics similar to those of BCO and SRO.",2102.06669v2
+2023-06-21,Sayonara BCS: Realization of Room Temperature Superconductivity as a result of a First Order Phase Transition,"By making periodic thru-holes in a suspended film, the phonon system can be
+modified. Motivated by the BCS theory, the technique -- so-called phonon
+engineering -- was applied to a metallic niobium sheet. It was found that its
+electrical resistance dropped to zero at 175 K, and the zero-resistance state
+persisted up to 290 K in the subsequent warming process. Despite the initial
+motivation, neither these high transition temperatures nor the phase transition
+with thermal hysteresis can be accounted for by the BCS theory. Therefore, we
+abandon the BCS theory. Instead, it turns out that the metallic holey sheet is
+partly oxidized to form a niobium-oxygen square lattice, which has points of
+resemblance to a copper-oxygen plane, the fundamental component of cuprate
+high-$T_{c}$ superconductors. Therefore, the pairing mechanism underlying this
+study should be related to that of cuprate high-$T_{c}$ superconductors, which
+we may not yet understand. In addition to the electrical results of zero
+resistance, the holey sheet exhibited a decrease in magnetization upon cooling,
+i.e., the Meissner effect. Moreover, the remnant magnetization was clearly
+detected at 300 K, which can only be attributed to persistent currents flowing
+in a superconducting sample. Thus, this study meets the established criteria
+for a conclusive demonstration of true superconductivity. Finally, the
+superconducting transition with the unambiguous thermal hysteresis is
+discussed. According to Halperin, Lubensky, and Ma, or HLM for short, any
+superconducting transition must always be first order with thermal hysteresis
+because of the intrinsic fluctuating magnetic field. The HLM theory is very
+compatible with the highly oriented system harboring two-dimensional
+superconductivity.",2306.13172v3
+2024-01-15,Room-temperature intrinsic ferromagnetism of two-dimensional Na2Cl crystals originated by s- and p-orbitals,"Ferromagnetism, as one of the most valuable properties of materials, has
+attracted sustained and widespread interest in basic and applied research from
+ancient compasses to modern electronic devices. Traditionally, intrinsic
+ferromagnetism has been attributed to the permanent magnetic moment induced by
+partially filled d- or f-orbitals. However, the development of ferromagnetic
+materials has been limited by this electronic structure convention. Thus, the
+identification of additional materials that are not constrained by this
+conventional rule but also exhibit intrinsic ferromagnetism is highly expected
+and may impact all the fields based on ferromagnetism. Here, we report the
+direct observation of room-temperature intrinsic ferromagnetism in
+two-dimensional (2D) Na2Cl crystals, in which there are only partially filled
+s- and p-orbitals rather than d- or f-orbitals, using the superconducting
+quantum interference device (SQUID) and magnetic force microscope (MFM). These
+Na2Cl crystals formed in reduced graphene oxide (rGO) membranes have an
+unconventional stoichiometric structure leading to unique electron and spin
+distributions. And the structure of these 2D Na2Cl crystals, including the Na
+and Cl sites, is characterized in situ for the first time and directly observed
+by cryo-electron microscopy (cryo-EM) based on the observed difference in
+contrast between Na stacked with Cl and single Na. These findings break the
+conventional rule of intrinsic ferromagnetism and provide new insights into the
+design of novel magnetic and electronic devices and transistors with a size
+down to the atomic scale.",2401.07524v1
+2011-08-02,Analysis of Sulfur Poisoning on a PEM Fuel Cell Electrode,"The extent of irreversible deactivation of Pt towards hydrogen oxidation
+reaction (HOR) due to sulfur adsorption and subsequent electrochemical
+oxidation is quantified in a functional PEM fuel cell. At 70 {\deg}C,
+sequential hydrogen sulfide (H2S) exposure and electrochemical oxidation
+experiments indicate that as much as 6% of total Pt sites are deactivated per
+monolayer sulfur adsorption at open circuit potential of a PEM fuel cell
+followed by its removal. The extent of such deactivation is much higher when
+the electrode is exposed to H2S when the fuel cell is operating at a finite
+load, and is dependent on the local overpotential and the duration of exposure.
+Regardless of this deactivation, the H2/O2 polarization curves obtained on
+post-recovery electrodes do not show performance losses suggesting that such
+performance curves alone cannot be used to assess the extent of recovery due to
+sulfur poisoning. A concise mechanism for the adsorption and electro-oxidation
+of H2S on Pt anode is presented. H2S dissociatively adsorbs onto Pt as two
+different sulfur species and at intermediate oxidation potentials, undergoes
+electro-oxidation to sulfur and then to sulfur dioxide (SO2). This mechanism is
+validated by charge balances between hydrogen desorption and sulfur
+electro-oxidation on Pt. The ignition potential for sulfur oxidation decreases
+with increase in temperature, which coupled with faster electro-oxidation
+kinetics result in the easier removal of adsorbed sulfur at higher
+temperatures. Furthermore, the adsorption potential is found to influence
+sulfur coverage of an electrode exposed to H2S. As an implication, the local
+potential of a PEM fuel cell anode exposed to H2S contaminated fuel should be
+kept below the equilibrium potential for sulfur oxidation to prevent
+irreversible loss of Pt sites.",1108.0609v1
+2016-11-10,Evolutionary optimization of a charge transfer ionic potential model for Ta/Ta-oxide hetero-interfaces,"Tantalum, tantalum oxide and their hetero-interfaces are of tremendous
+technological interest in several applications spanning electronics, thermal
+management, catalysis and biochemistry. For example, local oxygen stoichiometry
+variation in TaOx memristors comprising of metallic (Ta) and insulating oxide
+(Ta2O5) have been shown to result in fast switching on the sub-nanosecond
+timescale over a billion cycles, relevant to neuromorphic computation. Despite
+its broad importance, an atomistic scale understanding of oxygen stoichiometry
+variation across Ta/TaOx hetero-interfaces, such as during early stages of
+oxidation and oxide growth, is not well understood. This is mainly due to the
+lack of a variable charge interatomic potential model for tantalum oxides that
+can accurately describe the ionic interactions in the metallic (Ta) and oxide
+(TaOx) environment as well as at their interfaces. To address this challenge,
+we introduce a charge transfer ionic potential (CTIP) model for Ta/Ta-oxide
+system by training against lattice parameters, cohesive energies, equations of
+state, and elastic properties of various experimentally observed Ta2O5
+polymorphs. The best set of CTIP parameters are determined by employing a
+single-objective global optimization scheme driven by genetic algorithms
+followed by local Simplex optimization. Our newly developed CTIP potential
+accurately predicts structure, thermodynamics, energetic ordering of
+polymorphs, as well as elastic and surface properties of both Ta and Ta2O5, in
+excellent agreement with DFT calculations and experiments. We employ our newly
+parameterized CTIP potential to investigate the early stages of oxidation of Ta
+at different temperatures and atomic/molecular nature of the oxidizing species.",1611.03519v2
+2017-10-25,High-temperature cyclic oxidation kinetics and microstructural transition mechanisms of Ti-6Al-4V composites reinforced with hybrid (TiC+TiB) networks,"The microstructural features and high-temperature oxidation resistance of
+hybrid (TiC+TiB) networks reinforced Ti-6Al-4V composites were investigated
+after fabricated with reaction hot pressing technique. The inhomogeneous
+distribution of hybrid reinforcers resulted in a sort of stress-induced grain
+refinement for {\alpha}-Ti matrix phase, which was further facilitated by
+heterogeneous nucleation upon additive interfaces. HRTEM analyses revealed the
+crystallographic orientation relation between TiB and alpha-Ti phases as
+(201)TiB//(-1100)alpha-Ti plus [11-2]//[0001] alpha-Ti, while TiC and
+{\alpha}-Ti phases maintained the interrelation of (-200)TiC//(-2110)
+{\alpha}-Ti and [001]TiC//[01-10] alpha-Ti. The hybridly reinforced
+Ti-6Al-4V/(TiC+TiB) composites displayed superior oxidation resistance to both
+the sintered matrix alloy and the two composites reinforced solely with TiC or
+TiB addition during the cyclic oxidation at 873, 973 and 1073 K respectively
+for 100 h. The hybrid reinforcers volume fraction was a more influential factor
+to improve oxidation resistance than the matrix alloy powder size. As
+temperature rose from 873 to 1073 K, the oxidation kinetics transferred from
+the nearly parabolic type through qusilinear tendency into the finally linear
+mode. This corresponded to the morphological transition of oxide scales from a
+continuous protective film to a partially damaged layer and ended up with the
+complete spallation of alternating alumina and rutile multilayers. A
+phenomenological model was proposed to elucidate the growth process of oxides
+scales. The release of thermal stress, the suppression of oxygen diffusion and
+the fastening of oxide adherence were found as the three major mechanisms to
+enhance the oxidation resistance of hybrid reinforced composites.",1710.09315v1
+2019-10-24,Hybrid Organic-Metal Oxide Multilayer Channel Transistors with Record Operational Stability,"Metal oxide thin-film transistors are fast becoming a ubiquitous technology
+for application in driving backplanes of organic light-emitting diode displays.
+Currently all commercial products rely on metal oxides processed via physical
+vapor deposition methods. Transition to simpler, higher throughput
+manufacturing methods such as solution-based processes, are currently been
+explored as cost-effective alternatives. However, developing printable oxide
+transistors with high carrier mobility and bias-stable operation has proved
+challenging. Here we show that hybrid multilayer channels composed of
+alternating ultra-thin layers ($\leq$4 nm) of indium oxide, zinc oxide
+nanoparticles, ozone-treated polystyrene and a compact zinc oxide layer, all
+solution-processed in ambient atmosphere, can be used to create TFTs with
+remarkably high electron mobility (50 cm$^{2}$/Vs) and record operational
+stability. Insertion of the ozone-treated polystyrene interlayer is shown to
+reduce the concentration of electron traps at the metal oxide surfaces and
+heterointerfaces. The resulting transistors exhibit dramatically enhanced bias
+stability over 24 h continuous operation and while subjected to large electric
+field flux density (2.1$\times$10$^{-6}$ C/cm$^{2}$) with no adverse effects on
+the electron mobility. Density functional theory calculations identify the
+origin of this enhanced stability as the passivation of the oxygen
+vacancy-related gap states due to interaction between ozonolyzed styrene
+moieties and the oxides. Our results sets new design guidelines for bias-stress
+resilient metal oxide transistors.",1910.11013v1
+2018-06-04,Water Oxidation Chemistry of Oxynitrides and Oxides: Comparing NaTaO$_3$ and SrTaO$_2$N,"The oxygen evolution reaction (OER) plays an important role in evaluating a
+photocatalyst and to understand its surface chemistry. In this work we present
+a comparative study of the OER on the oxide NaTaO$_3$ (113) surface and the
+oxynitride SrTaO$_2$N (001) surface. Oxynitrides are highly promising
+photocatalysts due to their smaller band gap and resulting better visible light
+absorption compared to oxides but our knowledge about their surface structure
+and chemistry is still very limited. With the goal to compare the surface
+chemistry of oxides and oxynitrides, we perform density functional theory
+calculations to obtain the free energy changes associated with the OER reaction
+steps. For the OER at the Ta site of the clean surfaces, our results predict
+the rate-limiting step for both materials to be the formation of the *OOH
+intermediate, with a larger overpotential for the oxide than the oxynitride
+(1.30 V vs 1.01 V). The Na site is found to be more active than the Ta site on
+the oxide surface with an OER overpotential of 0.88 V, whereas the OER at the
+Sr site on the oxynitride has an overpotential of 1.14 V. For the A sites,
+contrary to the Ta site, the deprotonation of *OH was found to be the
+rate-limiting step. Computed Pourbaix diagrams show that at relevant
+(photo)electrochemical conditions all surfaces are covered with oxygen
+adsorbates. Oxygen adsorbates at A (Na, Sr) sites are however found to couple
+and desorb as O$_2$, leaving these sites empty under typical operating
+conditions. Following this desorption, we find the OER to proceed by the
+conventional *OOH mechanism on the SrO termination of the oxynitride but by a
+direct coupling of neighbouring *O at Na sites on the oxide surface. This
+coupling mechanism on the oxide has the smallest overpotential of 0.79 V
+compared to 0.88 V for the oxynitride, implying that the oxide is a better OER
+catalyst.",1806.01252v1
+1996-07-15,Non Fermi-Liquid States and Pairing of a general Model of Copper-Oxide Metals,"A model of copper-oxygen bonding and anti-bonding bands with the most general
+two-body interactions allowable by symmetry is considered. The model has a
+continuous transition as a function of hole-density x and temperature T to a
+phase in which a current circulates in each unit cell. This phase preserves the
+translational symmetry of the lattice while breaking time-reversal invariance
+and the four-fold rotational symmetry. The product of time-reversal and
+four-fold rotation is preserved. The circulating current phase terminates at a
+critical point at $x=x_c, T=0$. In the quantum-critical region about this point
+the logarithm of the frequency of the current fluctuations scales with their
+momentum. The microscopic basis for the marginal Fermi-liquid phenemenology and
+the observed long wavelength transport anomalies near $x=x_c$ are derived from
+such fluctuations. The symmetry of the current fluctuations is such that the
+associated magnetic field fluctuations are absent at oxygen sites and have the
+correct form to explain the anomalous copper nuclear relaxation rate.
+Cross-overs to the Fermi-liquid phase on either side of $x_c$ and the role of
+disorder are briefly considered. The current fluctuations promote
+superconductive instability with a propensity towards ``D-wave"" symmetry or
+``extended S-wave""symmetry depending on details of the band-structure.",9607105v2
+1999-06-30,Spin gap and magnetic coherence in a clean high-T_c superconductor,"A notable aspect of high-temperature superconductivity in the copper oxides
+is the unconventional nature of the underlying paired-electron state. A direct
+manifestation of the unconventional state is a pairing energy - that is, the
+energy required to remove one electron from the superconductor - that varies
+(between zero and a maximum value) as a function of momentum or wavevector: the
+pairing energy for conventional superconductors is wavevector-independent. The
+wavefunction describing the superconducting state will include not only the
+pairing of charges, but also of the spins of the paired charges. Each pair is
+usually in the form of a spin singlet, so there will also be a pairing energy
+associated with transforming the spin singlet into the higher energy spin
+triplet form without necessarily unbinding the charges. Here we use inelastic
+neutron scattering to determine the wavevector-dependence of spin pairing in
+La_{2-x}Sr_xCuO_4, the simplest high-temperature superconductor. We find that
+the spin pairing energy (or 'spin gap') is wavevector independent, even though
+superconductivity significantly alters the wavevector dependence of the spin
+fluctuations at higher energies.",9906456v1
+2002-03-22,Roles of Electron Correlations in the Spin-Triplet Superconductivity of Sr2RuO4,"We discuss a microscopic mechanism of the spin-tiplet superconductivity in
+the quasi-two-dimensional ruthenium oxide Sr2RuO4 on the basis of
+two-dimensional three-band Hubbard model. We solve the linearized Eliashberg
+equation by taking into account the full momentum-frequency dependence of the
+order parameter for the spin-triplet and the spin-singlet states, and estimate
+the transition temperature as a function of the Coulomb integrals. The
+effective pairing interaction is expanded perturbatively with respect to the
+Coulomb interaction at the Ru sites up to the third order. As a result, we show
+that the spin-triplet p-wave state is more stable than the spin-singlet d-wave
+state for moderately strong Coulomb interaction. Our results suggest that one
+of the three bands, $\gamma$, plays a dominant role in the superconducting
+transition, and the pairing on the other two bands($\alpha$ and $\beta$) is
+induced passively through the inter-orbit couplings. The most significant
+momentum dependence for the p-wave pairing originates from the vertex
+correction terms, while the incommensurate antiferromagnetic spin fluctuations,
+which are observed in inelastic neutron scattering experiments, are expected to
+disturb the p-wave pairing by enhancing the d-wave pairing. Therefore we can
+regard the spin-triplet superconductivity in Sr2RuO4 as one of the natural
+results of the electron correlations, and cannot consider as a result of some
+strong magnetic fluctuations. We will also mention the normal Fermi liquid
+properties of Sr2RuO4.",0203453v2
+2002-08-27,Angle-resolved photoemission spectroscopy of the cuprate superconductors,"This paper reviews the most recent ARPES results on the cuprate
+superconductors and their insulating parent and sister compounds, with the
+purpose of providing an updated summary of the extensive literature in this
+field. The low energy excitations are discussed with emphasis on some of the
+most relevant issues, such as the Fermi surface and remnant Fermi surface, the
+superconducting gap, the pseudogap and d-wave-like dispersion, evidence of
+electronic inhomogeneity and nano-scale phase separation, the emergence of
+coherent quasiparticles through the superconducting transition, and many-body
+effects in the one-particle spectral function due to the interaction of the
+charge with magnetic and/or lattice degrees of freedom. The first part of the
+paper introduces photoemission spectroscopy in the context of strongly
+interacting systems, along with an update on the state-of-the-art
+instrumentation. The second part provides a brief overview of the scientific
+issues relevant to the investigation of the low energy electronic structure by
+ARPES. The rest of the paper is devoted to the review of experimental results
+from the cuprates and the discussion is organized along conceptual lines:
+normal-state electronic structure, interlayer interaction, superconducting gap,
+coherent superconducting peak, pseudogap, electron self energy and collective
+modes. Within each topic, ARPES data from the various copper oxides are
+presented.",0208504v1
+2003-05-19,Superconductivity Phase Diagram of Na(x)CoO(2).1.3H(2)O,"Although the microscopic origin of the superconductivity in high Tc copper
+oxides remains the subject of active inquiry, several of their electronic
+characteristics are well established as universal to all the known materials,
+forming the experimental foundation that all theories must address. The most
+fundamental of those characteristics is the dependence of the superconducting
+transition temperature on the degree of electronic band filling. Since the
+discovery of cuprate superconductivity in 1986 (1), the search for other
+families of superconductors that might help shed light on the superconducting
+mechanism of the cuprates has been of great interest. The recent report of
+superconductivity near 4K in the triangular lattice, layered sodium cobalt
+oxyhydrate, Na0.35CoO2.1.3H2O, is the best indication that superconductors
+related to the cuprates may be found (2). Here we show that the superconducting
+transition temperature of this compound displays the same kind of band-filling
+behavior that is observed in the cuprates. Specifically, that the optimal
+superconducting Tc occurs in a narrow range of band filling, and decreases for
+both underdoped and overdoped materials, in dramatic analogy to the phase
+diagram of the cuprate superconductors. Our results suggest that
+characterization of the detailed electronic and magnetic behavior of these new
+materials may help establish which of the many special characteristics of the
+cuprates is fundamental to their high Tc superconductivity.",0305450v2
+2004-03-13,Interplay of structural and electronic phase separation in single crystalline La(2)CuO(4.05) studied by neutron and Raman scattering,"We report a neutron and Raman scattering study of a single-crystal of
+La(2)CuO(4.05) prepared by high temperature electrochemical oxidation. Elastic
+neutron scattering measurements show the presence of two phases, corresponding
+to the two edges of the first miscibility gap, all the way up to 300 K. An
+additional oxygen redistribution, driven by electronic energies, is identified
+at 250 K in Raman scattering (RS) experiments by the simultaneous onset of
+two-phonon and two-magnon scattering, which are fingerprints of the insulating
+phase. Elastic neutron scattering measurements show directly an
+antiferromagnetic ordering below a N\'eel temperature of T_N =210K. The opening
+of the superconducting gap manifests itself as a redistribution of electronic
+Raman scattering below the superconducting transition temperature, T_c = 24K. A
+pronounced temperature-dependent suppression of the intensity of the (100)
+magnetic Bragg peak has been detected below T_c. We ascribe this phenomenon to
+a change of relative volume fraction of superconducting and antiferromagnetic
+phases with decreasing temperature caused by a form of a superconducting
+proximity effect.",0403340v1
+2004-04-02,Stability of $π$ junction configurations in ferromagnet-superconductor heterostructures,"We investigate the stability of possible order parameter configurations in
+clean layered heterostructures of the $SFS...FS$ type, where $S$ is a
+superconductor and $F$ a ferromagnet. We find that for most reasonable values
+of the geometric parameters (layer thicknesses and number) and of the material
+parameters (such as magnetic polarization, wavevector mismatch, and oxide
+barrier strength) several solutions of the {\it self consistent} microscopic
+equations can coexist, which differ in the arrangement of the sequence of ``0''
+and ``$\pi$'' junction types (that is, with either same or opposite sign of the
+pair potential in adjacent $S$ layers). The number of such coexisting self
+consistent solutions increases with the number of layers. Studying the relative
+stability of these configurations requires an accurate computation of the small
+difference in the condensation free energies of these inhomogeneous systems. We
+perform these calculations, starting with numerical self consistent solutions
+of the Bogoliubov-de Gennes equations. We present extensive results for the
+condensation free energies of the different possible configurations, obtained
+by using efficient and accurate numerical methods, and discuss their relative
+stabilities. Results for the experimentally measurable density of states are
+also given for different configurations and clear differences in the spectra
+are revealed. Comprehensive and systematic results as a function of the
+relevant parameters for systems consisting of three and seven layers (one or
+three junctions) are given, and the generalization to larger number of layers
+is discussed.",0404058v1
+2004-06-05,Dependence of the superconducting critical temperature on the number of layers in homologous series of high-Tc cuprates,"We study a model of $n$-layer high-temperature cuprates of homologous series
+like HgBa_2Ca_(n-1)Cu_nO_(2+2n+\delta) to explain the dependence of the
+critical temperature Tc(n) on the number $n$ of Cu-O planes in the elementary
+cell. Focusing on the description of the high-temperature superconducting
+system in terms of the collective phase variables, we have considered a
+semi-microscopic anisotropic three-dimensional vector XY model of stacked
+copper-oxide layers with adjustable parameters representing microscopic
+in-plane and out-of-plane phase stiffnesses. The model captures the layered
+composition along c-axis of homologous series and goes beyond the
+phenomenological Lawrence-Doniach model for layered superconductors.
+Implementing the spherical closure relation for vector variables we have solved
+the phase XY model exactly with the help of transfer matrix method and
+calculated Tc(n) for arbitrary block size $n$, elucidating the role of the
+c-axis anisotropy and its influence on the critical temperature. Furthermore,
+we accommodate inhomogeneous charge distribution among planes characterized by
+the charge imbalance coefficient $R$ being the function of number of layers
+$n$. By making a physically justified assumption regarding the doping
+dependence of the microscopic phase stiffnesses, we have calculated the values
+of parameter $R$ as a function of block size $n$ in good agreement with the
+nuclear magnetic resonance data of carrier distribution in multilayered high-Tc
+cuprates.",0406142v1
+2004-07-20,Synthesis of Colloidal Mn2+:ZnO Quantum Dots and High-TC Ferromagnetic Nanocrystalline Thin Films,"We report the synthesis of colloidal Mn2+-doped ZnO (Mn2+:ZnO) quantum dots
+and the preparation of room-temperature ferromagnetic nanocrystalline thin
+films. Mn2+:ZnO nanocrystals were prepared by a hydrolysis and condensation
+reaction in DMSO under atmospheric conditions. Synthesis was monitored by
+electronic absorption and electron paramagnetic resonance (EPR) spectroscopies.
+Zn(OAc)2 was found to strongly inhibit oxidation of Mn2+ by O2, allowing the
+synthesis of Mn2+:ZnO to be performed aerobically. Mn2+ ions were removed from
+the surfaces of as-prepared nanocrystals using dodecylamine to yield
+high-quality internally doped Mn2+:ZnO colloids of nearly spherical shape and
+uniform diameter (6.1 +/- 0.7 nm). Simulations of the highly resolved X- and
+Q-band nanocrystal EPR spectra, combined with quantitative analysis of magnetic
+susceptibilities, confirmed that the manganese is substitutionally incorporated
+into the ZnO nanocrystals as Mn2+ with very homogeneous speciation, differing
+from bulk Mn2+:ZnO only in the magnitude of D-strain. Robust ferromagnetism was
+observed in spin-coated thin films of the nanocrystals, with 300 K saturation
+moments as large as 1.35 Bohr magneton/Mn2+ and TC > 350 K. A distinct
+ferromagnetic resonance signal was observed in the EPR spectra of the
+ferromagnetic films. The occurrence of ferromagnetism in Mn2+:ZnO and its
+dependence on synthetic variables are discussed in the context of these and
+previous theoretical and experimental results.",0407500v1
+2004-10-29,Quantum Mott Transition and Multi-Furcating Criticality,"Phenomenological theory of the Mott transition is presented. When the
+critical temperature of the Mott transition is much higher than the quantum
+degeneracy temperature, the transition is essentially described by the Ising
+universality class. Below the critical temperature, phase separation or
+first-order transition occurs. However, if the critical point is involved in
+the Fermi degeneracy region, a marginal quantum critical point appears at zero
+temperature. The originally single Mott critical point generates subsequent
+many unstable fixed points through various Fermi surface instabilities induced
+by the Mott criticality characterized by the diverging charge susceptibility or
+doublon susceptibility. This occurs in marginal quantum-critical region.
+Charge, magnetic and superconducting instabilitites compete severely under
+these critical charge fluctuations. The quantum Mott transition triggers
+multi-furcating criticality, which goes beyond the conventional concept of
+multicriticality in quantum phase transitions. Near the quantum Mott
+transition, the criticality generically drives growth of inhomogeneous
+structure in the momentum space with singular points of flat dispersion on the
+Fermi surface. The singular points determine the quantum dynamics of the Mott
+transition by the dynamical exponent $z=4$. We argue that many of
+filling-control Mott transitions are classified to this category. Recent
+numerical results as well as experimental results on strongly correlated
+systems including transition metal oxides, organic materials and $^3$He layer
+adsorbed on a substrate are consistently analyzed especially in two-dimensional
+systems.",0410753v1
+2004-11-04,W=0 pairing in Hubbard and related models of low-dimensional superconductors,"Lattice Hamiltonians with on-site interaction $W$ have W=0 solutions, that
+is, many-body {\em singlet} eigenstates without double occupation. In
+particular, W=0 pairs give a clue to understand the pairing force in repulsive
+Hubbard models. These eigenstates are found in systems with high enough
+symmetry, like the square, hexagonal or triangular lattices. By a general
+theorem, we propose a systematic way to construct all the W=0 pairs of a given
+Hamiltonian. We also introduce a canonical transformation to calculate the
+effective interaction between the particles of such pairs. In geometries
+appropriate for the CuO$_{2}$ planes of cuprate superconductors, armchair
+Carbon nanotubes or Cobalt Oxides planes, the dressed pair becomes a bound
+state in a physically relevant range of parameters. We also show that W=0 pairs
+quantize the magnetic flux like superconducting pairs do. The pairing mechanism
+breaks down in the presence of strong distortions. The W=0 pairs are also the
+building blocks for the antiferromagnetic ground state of the half-filled
+Hubbard model at weak coupling. Our analytical results for the $4\times 4$
+Hubbard square lattice, compared to available numerical data, demonstrate that
+the method, besides providing intuitive grasp on pairing, also has quantitative
+predictive power. We also consider including phonon effects in this scenario.
+Preliminary calculations with small clusters indicate that vector phonons
+hinder pairing while half-breathing modes are synergic with the W=0 pairing
+mechanism both at weak coupling and in the polaronic regime.",0411101v1
+2005-01-05,Hole crystallization in the spin ladder of Sr14Cu24O41,"One of the deepest questions in condensed matter physics concerns what other
+phases compete with superconductivity in high-transition-temperature (high-Tc)
+superconductors. One candidate is the ""stripe"" phase, in which the carriers
+(holes) condense into rivers of charge separating regions of
+antiferromagnetism. A related but lesser known system is the ""spin ladder"",
+which consists of two coupled chains of magnetic ions forming an array of
+rungs. A doped ladder can be thought of as a high-Tc material with lower
+dimensionality, and has been predicted to exhibit both superconductivity and an
+insulating ""hole crystal"" phase in which the carriers are localised through
+many-body interactions. The competition between the two resembles that between
+static stripes and superconductivity in high-Tc materials. Here we report
+evidence, from resonant x-ray scattering, for the existence of a hole crystal
+in the doped spin ladder of Sr14Cu24O41. This phase exists without a detectable
+distortion in the structural lattice, indicating it arises from many-body
+effects. Our measurements confirm theoretical predictions and support the
+picture that proximity to charge ordered states is a general property of
+superconductivity in copper-oxides.",0501087v1
+2005-09-21,Effect of iron-doping on spin-state transition and ferromagnetism in Pr$_{0.5}$Ca$_{0.5}$CoO$_{3-δ}$ cobalt oxides,"Resistivity and dc magnetization measurements were performed for the
+polycrystalline Pr$_{0.5}$Ca$_{0.5}$Co$_{1-x}$Fe$_{x}$O$_{3-\delta}$ ($x$ = 0,
+0.05, 0.10 and 0.15) samples. The as-fabricated samples exhibit ferromagnetic
+(FM) transition and the transition temperature increases with increasing the
+iron doping level. Annealing under high oxygen pressure induces a spin-state
+transition of Co ions in the \emph{iron-free} sample and such transition is
+reinforced with increasing the annealing oxygen pressure, while the annealing
+under high oxygen pressure suppresses the ferromagnetic ordering. Contrary to
+the case of the \emph{iron-free} sample, no spin-state transition is induced by
+the annealing under high oxygen pressure for the \emph{iron-doped} samples, and
+the ferromagnetic transition temperature is nearly independent of the annealing
+procedures. The enhancement of the spin-state transition in the
+\emph{iron-free} sample after annealing under high oxygen pressure should be
+attributed to the reduction of the cell volume. The suppression of the
+spin-state transition by the Fe doping is related to the enlargement of the
+cell volume and the stronger Fe-O bonds than Co-O bonds. The enhancement of the
+ferromagnetism by the iron-doping might arise from the ferromagnetic exchange
+interaction between Fe$^{3+}$ and Co$^{4+}$ through oxygen
+(Fe$^{3+}$-O-Co$^{4+}$).",0509533v1
+2005-11-01,"Spatially modulated ""Mottness"" in La2-xBaxCuO4","Stripe phases were predicted to arise in doped antiferromagnets through
+competition between magnetism and the kinetic energy of mobile carriers
+(typically holes). In copper-oxides the main experimental evidence for stripes
+is neutron scattering from La1.48Nd0.4Sr0.12CuO4 (LNSCO) and La1.875Ba0.125CuO4
+(LBCO) which reveals coexisting static spin and charge order whose wavelengths
+differ by a factor of two, reminiscent of charged rivers separating regions of
+oppositely-phased antiferromagnetism. A neutron is an electrically neutral
+object, however, so does not detect charge but rather its associated lattice
+distortion ; it is not known if the ""stripe"" phase in LNSCO and LBCO actually
+involves ordering of the doped holes. Here we present a study of the charge
+order in LBCO with resonant soft x-ray scattering (RSXS). We observe giant
+resonances at both the mobile carrier and upper-Hubbard band features in the OK
+edge. These demonstrate a substantial modulation in the doped hole density as
+well as the amount of spectral weight near the correlated gap, i.e. the degree
+of ""Mottness"". The peak-to-trough amplitude of the valence modulation is
+estimated to be 0.063 holes, which if interpreted with a model of the stripe
+form factor suggests an integrated area of 0.59 holes under a single stripe.
+While only an estimate, this number agrees with what is expected for
+half-filled stripes.",0511019v1
+2005-12-03,Electron-phonon coupling reflecting dynamic charge inhomogeneity in copper-oxide superconductors,"The attempt to understand cuprate superconductors is complicated by the
+presence of multiple strong interactions. While many believe that
+antiferromagnetism is important for the superconductivity, there has been
+revived interest in the role of electron-lattice coupling. The recently studied
+conventional superconductor MgB2 has a very strong electron-lattice coupling,
+involving a particular vibrational mode (phonon), that was predicted by
+standard theory and confirmed quantitatively by experiment. Here we present
+inelastic scattering measurements that show a similarly strong anomaly in the
+Cu-O bond-stretching phonon in the cuprate superconductors La2-xSrxCuO4 (with
+x=0.07, 0.15). This is in contrast to conventional theory, which does not
+predict such behavior. The anomaly is strongest in La1.875Ba0.125CuO4 and
+La1.48Nd0.4Sr0.12CuO4, compounds that exhibit spatially modulated charge and
+magnetic order, often called stripe order. It occurs at a wave vector
+corresponding to the charge order. These results suggest that this giant
+electron-phonon anomaly, which is absent in undoped and over-doped
+non-superconductors, is associated with charge inhomogeneity. It follows that
+electron-phonon coupling may be important to our understanding of
+superconductivity, although its contribution to the mechanism is likely to be
+indirect.",0512063v2
+2006-03-01,Theoretical Aspects of Charge Ordering in Molecular Conductors,"Theoretical studies on charge ordering phenomena in quarter-filled molecular
+(organic) conductors are reviewed. Extended Hubbard models including not only
+the on-site but also the inter-site Coulomb repulsion are constructed in a
+straightforward way from the crystal structures, which serve for individual
+study on each material as well as for their systematic understandings. In
+general the inter-site Coulomb interaction stabilizes Wigner crystal-type
+charge ordered states, where the charge localizes in an arranged manner
+avoiding each other, and can drive the system insulating. The variety in the
+lattice structures, represented by anisotropic networks in not only the
+electron hopping but also in the inter-site Coulomb repulsion, brings about
+diverse problems in low-dimensional strongly correlated systems. Competitions
+and/or co-existences between the charge ordered state and other states are
+discussed, such as metal, superconductor, and the dimer-type Mott insulating
+state which is another typical insulating state in molecular conductors.
+Interplay with magnetism, e.g., antiferromagnetic state and spin gapped state
+for example due to the spin-Peierls transition, is considered as well. Distinct
+situations are pointed out: influences of the coupling to the lattice degree of
+freedom and effects of geometrical frustration which exists in many molecular
+crystals. Some related topics, such as charge order in transition metal oxides
+and its role in new molecular conductors, are briefly remarked.",0603008v2
+2007-08-29,X-ray Anomalous Scattering of Diluted Magnetic Oxide Semiconductors: Possible Evidence of Lattice Deformation for High Temperature Ferromagnetism,"We have examined whether the Co ions crystallographically substitute on the
+Ti sites in rutile and anatase Ti_{1-x}$Co$_{x}$O$_{2-delta}$ thin films that
+exhibit room-temperature ferromagnetism. Intensities of the x-ray Bragg
+reflection from the films were measured around the $K$-absorption-edge of Co.
+If the Co ions randomly substitute on the Ti sites, the intensity should
+exhibit an anomaly due to the anomalous dispersion of the atomic scattering
+factor of Co. However, none of the anatase and rutile samples did exhibit an
+anomaly, unambiguously showing that the Co ions in
+Ti$_{1-x}$Co$_{x}$O$_{2-delta}$ are not exactly located at the Ti sites of
+TiO$_2$. The absence of the anomaly is probably caused by a significant
+deformation of the local structure around Co due to the oxygen vacancy. We have
+applied the same method to paramagnetic Zn$_{1-x}$Co$_{x}$O thin films and
+obtained direct evidence that the Co ions are indeed substituted on the Zn
+sites.",0708.3876v1
+2007-09-14,An inhomogeneous Josephson phase in thin-film and High-Tc superconductors,"In many cases inhomogeneities are known to exist near the metal (or
+superconductor)-insulator transition, as follows from well-known domain-wall
+arguments. If the conducting regions are large enough (i.e. when the T=0
+superconducting gap is much larger than the single-electron level spacing), and
+if they have superconducting correlations, it becomes energetically favorable
+for the system to go into a Josephson-coupled zero-resistance state before
+(i.e. at higher resistance than) becoming a ""real"" metal. We show that this is
+plausible by a simple comparison of the relevant coupling constants. For small
+grains in the above sense, the electronic grain structure is washed out by
+delocalization and thus becomes irrelevant. When the proposed ""Josephson state""
+is quenched by a magnetic field, an insulating, rather then a metallic, state
+should appear. This has been shown to be consistent with the existing data on
+oxide materials as well as ultra-thin films. We discuss the Uemura correlations
+versus the Homes law, and derive the former for the large-grain Josephson array
+(inhomogenous superconductor) model. The small-grain case behaves like a dirty
+homogenous metal. It should obey the Homes law provided that the system is in
+the dirty supeconductivity limit. A speculation why that is typically the case
+for d-wave superconductors is presented.",0709.2321v1
+2007-12-10,"Long Range Antiferromagnetic Ordering in the S = 1/2 Ordered Rock Salt Oxide, Li5OsO6: Comparison with the Isoelectronicand Isostructural Spin Glass, Li4MgReO6","Li5OsO6 and Li5ReO6 polycrystalline samples were synthesized by conventional
+solid state methods. Employing powder neutron diffraction data, the crystal
+structure of Li5OsO6 was re-investigated. Li5OsO6 crystallizes in C2/m space
+group in an ordered NaCl structure type where a = 5.0472(1) A, b = 8.7827(2) A,
+c = 5.0079(1) A, Beta = 109.777(2) degree and V = 208.90(1).A^3 Magnetic
+susceptibility and heat capacity data indicate an AFM long range order below
+40K although there is evidence for low dimensional short range order above 80K.
+As well, the frustration index, f = |theta|/TN ~1, in contrast to the
+isostructural and isoelectronic compound, Li4MgReO6, which is a spin glass
+below 12K and has f ~ 14. An attempt was made to rationalize these differences
+using spin dimer analysis. The key results are that the spin exchange
+interactions in the Re-based compound are stronger and are consistent with a
+frustrated triangular lattice model while a low dimensional short range order
+model is better for Li5OsO6. The main reason for this is a strong Jahn-Teller
+distortion in the OsO6 octahedron material which constrains the unpaired
+electron to occupy the dxy orbital.",0712.1580v1
+2008-02-20,Intersite 4p-3d hybridization in cobalt oxides: a resonant x-ray emission spectroscopy study,"We report on strong dipole transitions to 3d orbitals of neighboring Co atoms
+in the Co 1s x-ray absorption pre-edge. They are revealed by applying
+high-resolution resonant x-ray emission spectroscopy (RXES) to compounds
+containing CoO6 clusters. When contrasted to quadrupole local 1s3d excitations,
+these non-local 1s3d transitions are identified by their energy dispersion and
+angular dependence, their sensitivity to second-shell effects (i.e. the
+connection mode of the CoO6 octahedra and the bond lengths), and an upwards
+energy shift of 2.5 eV due to the poorer screening of the core hole. The
+experiment reveals that the intensity of the non-local transitions gauges the
+oxygen-mediated 4p-O-3d intersite hybridization. We propose a revised
+interpretation of the pre-edges of transition metal compounds. Detailed
+analysis of these new features in the pre-edge offers a unique insight in the
+oxygen mediated metal-metal interactions in transition metal-based systems,
+which is a crucial aspect in orbital ordering and related electronic and
+magnetic properties. In addition, the exceptional resolving power of the
+present 1s2p RXES experiment allows us to demonstrate the coherent second-order
+nature of the underlying scattering process.",0802.2744v1
+2008-05-08,Anomalous Hall Effect in Magnetite: Universal Scaling Relation Between Hall and Longitudinal Conductivity in Low-Conductivity Ferromagnets,"The anomalous Hall effect (AHE) has been studied systematically in the
+low-conductivity ferromagnetic oxide Fe$_{3-x}$Zn$_x$O$_4$ with $x = 0$, 0.1,
+and 0.5. We used (001), (110), and (111) oriented epitaxial
+Fe$_{3-x}$Zn$_x$O$_4$ films grown on MgO and sapphire substrates in different
+oxygen partial pressure to analyze the dependence of the AHE on
+crystallographic orientation, Zn content, strain state, and oxygen deficiency.
+Despite substantial differences in the magnetic properties and magnitudes of
+the anomalous Hall conductivity $\sigma_{xy}^{\rm AHE}$ and the longitudinal
+conductivity $\sigma_{xx}$ over several orders of magnitude, a universal
+scaling relation $\sigma_{xy}^{\rm AHE} \propto \sigma_{xx}^{\alpha}$ with
+$\alpha = 1.69 \pm 0.08$ was found for all investigated samples. Our results
+are in agreement with recent theoretical and experimental findings for
+ferromagnetic metals in the dirty limit, where transport is by metallic
+conduction. We find the same scaling relation for magnetite, where hopping
+transport prevails. The fact that this relation is independent of
+crystallographic orientation, Zn content, strain state, and oxygen deficiency
+suggests that it is universal and particularly does not depend on the nature of
+the transport mechanism.",0805.1120v1
+2008-05-15,Field-induced quantum critical route to a Fermi liquid in high-temperature superconductors,"In high transition temperature (T_c) superconductivity, charge doping is a
+natural tuning parameter that takes copper oxides from the antiferromagnet to
+the superconducting region. In the metallic state above T_c the standard
+Landau's Fermi-liquid theory of metals as typified by the temperature squared
+(T^2) dependence of resistivity appears to break down. Whether the origin of
+the non-Fermi-liquid behavior is related to physics specific to the cuprates is
+a fundamental question still under debate. We uncover a new transformation from
+the non-Fermi- to a standard Fermi-liquid state driven not by doping but by
+magnetic field in the overdoped high-T_c superconductor Tl_2Ba_2CuO_{6+x}. From
+the c-axis resistivity measured up to 45 T, we show that the Fermi-liquid
+features appear above a sufficiently high field which decreases linearly with
+temperature and lands at a quantum critical point near the superconductivity's
+upper critical field -- with the Fermi-liquid coefficient of the T^2 dependence
+showing a power-law diverging behavior on the approach to the critical point.
+This field-induced quantum criticality bears a striking resemblance to that in
+quasi-two dimensional heavy-Fermion superconductors, suggesting a common
+underlying spin-related physics in these superconductors with strong electron
+correlations.",0805.2215v1
+2008-06-05,"Antiferromagnetic, Charge and Orbital Ordered States of Na0.5CoO2 Based on the Two-Dimensional Triangular Lattice d-p Model","We investigate the electronic state of a CoO_2 plane in the layered cobalt
+oxides Na_xCoO_2 using the 11 band d-p model on a two-dimensional triangular
+lattice, where the tight-binding parameters are determined so as to fit the LDA
+band structure. Effects of the Coulomb interaction at a Co site: the intra- and
+inter-orbital direct terms U and U', the exchange coupling J and the
+pair-transfer J', are treated within the Hartree-Fock approximation. We also
+consider the effect of the Na order at x=0.5, where Na ions form
+one-dimensional chains, by taking into account of an effective one-dimensional
+potential Delta epsilon_{d}. It is found that the one-dimensional Na order
+enhances the Fermi surface nesting and antiferromagnetism is caused which is
+suppressed due to the frustration effect in the case without the Na order. %It
+is found that the Na order enhances the Fermi surface nesting resulting in a
+metallic antiferromagnetism which is suppressed due to the frustration effect
+in the case without the Na order. Furthermore, we consider the effect of the
+Coulomb interaction between the nearest-neighbor Co sites V and find that a
+coexistence of the magnetic, charge and orbital ordered state takes place for
+V>V_c where the system becomes insulator.",0806.0911v1
+2008-06-10,Unusual electron correlations in NaxCoO2 due to the spin-state quasidegeneracy of cobalt ions,"Recent studies exposed many remarkable properties of layered cobaltates
+NaxCoO2. Surprisingly, many-body effects have been found to increase at
+sodium-rich compositions of NaxCoO2 where one expects a simple, nearly free
+motion of the dilute S=1/2 holes doped into a band insulator NaCoO2. Here we
+discuss the origin of enigmatic correlations that turn a doped NaCoO2 into a
+strongly correlated electronic system. A minimal model including orbital
+degeneracy is proposed and its predictions are discussed. The model is based on
+a key property of cobalt oxides - the spin-state quasidegeneracy of CoO6
+octahedral complex - which has been known, e.g., in the context of an unusual
+physics of LaCoO3 compound. Another important ingredient of the model is the
+90-degree Co-O-Co bonding in NaxCoO2 which allows nearest-neighbor $t_{2g}-e_g$
+hopping. This hopping introduces a dynamical mixture of electronic
+configurations $t_{2g}^6, S=0$ and $t_{2g}^5e_g^1, S=1$ of neighboring cobalt
+ions. We show that scattering of charge carriers on spin-state fluctuations
+suppresses their coherent motion and leads to the spin-polaron physics at
+$x\sim 1$. At larger doping when coherent fermionic bands are formed, the model
+predicts singlet superconductivity of extended s-wave symmetry. The presence of
+low-lying spin states of Co$^{3+}$ is essential for the pairing mechanism.
+Implications of the model for magnetic orderings are also discussed.",0806.1682v1
+2008-06-25,Spin dynamics in the pseudogap state of a high-temperature superconductor,"The pseudogap is one of the most pervasive phenomena of high temperature
+superconductors. It is attributed either to incoherent Cooper pairing setting
+in above the superconducting transition temperature Tc, or to a hidden order
+parameter competing with superconductivity. Here we use inelastic neutron
+scattering from underdoped YBa(2)Cu(3)O(6.6) to show that the dispersion
+relations of spin excitations in the superconducting and pseudogap states are
+qualitatively different. Specifically, the extensively studied ""hour glass""
+shape of the magnetic dispersions in the superconducting state is no longer
+discernible in the pseudogap state and we observe an unusual ""vertical""
+dispersion with pronounced in-plane anisotropy. The differences between
+superconducting and pseudogap states are thus more profound than generally
+believed, suggesting a competition between these two states. Whereas the
+high-energy excitations are common to both states and obey the symmetry of the
+copper oxide square lattice, the low-energy excitations in the pseudogap state
+may be indicative of collective fluctuations towards a state with broken
+orientational symmetry predicted in theoretical work.",0806.4134v1
+2008-06-27,Electron pockets in the Fermi surface of hole-doped high-Tc superconductors,"High-temperature superconductivity occurs as copper oxides are chemically
+tuned to have a carrier concentration intermediate between their metallic state
+at high doping and their insulating state at zero doping. The underlying
+evolution of the electron system in the absence of superconductivity is still
+unclear and a question of central importance is whether it involves any
+intermediate phase with broken symmetry. The Fermi surface of underdoped
+YBa2Cu3Oy and YBa2Cu4O8 was recently shown to include small pockets in contrast
+with the large cylinder characteristic of the overdoped regime1, pointing to a
+topological change in the Fermi surface. Here we report the observation of a
+negative Hall resistance in the magnetic field-induced normal state of
+YBa2Cu3Oy and YBa2Cu4O8, which reveals that these pockets are electron-like. We
+propose that electron pockets arise most likely from a reconstruction of the
+Fermi surface caused by the onset of a density-wave phase, as is thought to
+occur in the electron-doped materials near the onset of antiferromagnetic order
+Comparison with materials of the La2CuO4 family that exhibit spin/charge
+density-wave order suggests that a Fermi surface reconstruction also occurs in
+those materials, pointing to a generic property of high-Tc superconductors.",0806.4621v1
+2009-02-12,"Manganite charge and orbitally ordered and disordered states probed by Fe substitution into Mn site in LnBaMn1.96Fe0.04O5, LnBaMn1.96Fe0.04O6 and LnBaMn1.96Fe0.04O5.5 (Ln=Y, Gd, Sm, Nd, Pr, La)","The layered manganese oxides LnBaMn1.96Fe0.04Oy (Ln=Y, Gd, Sm, Nd, Pr, La)
+have been synthesized for y=5, 5.5 and 6. In the oxygen-saturated state (y=6)
+they exhibit the charge and orbital order at ambient temperature for Ln=Y, Gd,
+Sm, but unordered eg-electronic system for Ln=La,Pr,Nd. Fourfold increase of
+quadrupole splitting was observed owing to the charge and orbital ordering.
+This is in agreement with the jumplike increase in distortion of the reduced
+perovskite-like cell for the charge and orbitally ordered manganites compared
+to the unordered ones. Substitution of 2 percents of Mn by Fe suppresses the
+temperatures of structural and magnetic transitions by 20 to 50 K. Parameters
+of the crystal lattices and the room-temperature M\""{o}ssbauer spectra were
+studied on forty samples whose structures were refined within five symmetry
+groups: P4/mmm, P4/nmm, Pm-3m, Icma and P2/m. Overwhelming majority of the Fe
+species are undifferentiated in the M\""{o}ssbauer spectra for most of the
+samples. Such the single-component spectra in the two-site structures are
+explained by the preference of Fe towards the site of Mn(III) and by the
+segmentation of the charge and orbitally ordered domains.",0902.2027v2
+2009-04-26,Anomalous Hall effect,"We present a review of experimental and theoretical studies of the anomalous
+Hall effect (AHE), focusing on recent developments that have provided a more
+complete framework for understanding this subtle phenomenon and have, in many
+instances, replaced controversy by clarity. Synergy between experimental and
+theoretical work, both playing a crucial role, has been at the heart of these
+advances. On the theoretical front, the adoption of Berry-phase concepts has
+established a link between the AHE and the topological nature of the Hall
+currents which originate from spin-orbit coupling. On the experimental front,
+new experimental studies of the AHE in transition metals, transition-metal
+oxides, spinels, pyrochlores, and metallic dilute magnetic semiconductors, have
+more clearly established systematic trends. These two developments in concert
+with first-principles electronic structure calculations, strongly favor the
+dominance of an intrinsic Berry-phase-related AHE mechanism in metallic
+ferromagnets with moderate conductivity. The intrinsic AHE can be expressed in
+terms of Berry-phase curvatures and it is therefore an intrinsic quantum
+mechanical property of a perfect cyrstal. An extrinsic mechanism, skew
+scattering from disorder, tends to dominate the AHE in highly conductive
+ferromagnets. We review the full modern semiclassical treatment of the AHE
+together with the more rigorous quantum-mechanical treatments based on the Kubo
+and Keldysh formalisms, taking into account multiband effects, and demonstrate
+the equivalence of all three linear response theories in the metallic regime.
+Finally we discuss outstanding issues and avenues for future investigation.",0904.4154v1
+2009-05-18,Two-orbital SU(N) magnetism with ultracold alkaline-earth atoms,"Fermionic alkaline-earth atoms have unique properties that make them
+attractive candidates for the realization of novel atomic clocks and degenerate
+quantum gases. At the same time, they are attracting considerable theoretical
+attention in the context of quantum information processing. Here we demonstrate
+that when such atoms are loaded in optical lattices, they can be used as
+quantum simulators of unique many-body phenomena. In particular, we show that
+the decoupling of the nuclear spin from the electronic angular momentum can be
+used to implement many-body systems with an unprecedented degree of symmetry,
+characterized by the SU(N) group with N as large as 10. Moreover, the interplay
+of the nuclear spin with the electronic degree of freedom provided by a stable
+optically excited state allows for the study of spin-orbital physics. Such
+systems may provide valuable insights into strongly correlated physics of
+transition metal oxides, heavy fermion materials, and spin liquid phases.",0905.2610v2
+2009-10-23,139La NMR evidence for phase solitons in the ground state of overdoped manganites,"Hole doped transition metal oxides are famous due to their extraordinary
+charge transport properties, such as high temperature superconductivity
+(cuprates) and colossal magnetoresistance (manganites). Astonishing, the mother
+system of these compounds is a Mott insulator, whereas important role in the
+establishment of the metallic or superconducting state is played by the way
+that holes are self-organized with doping. Experiments have shown that by
+adding holes the insulating phase breaks into antiferromagnetic (AFM) regions,
+which are separated by hole rich clumps (stripes) with a rapid change of the
+phase of the background spins and orbitals. However, recent experiments in
+overdoped manganites of the La(1-x)Ca(x)MnO(3) (LCMO) family have shown that
+instead of charge stripes, charge in these systems is organized in a uniform
+charge density wave (CDW). Besides, recent theoretical works predicted that the
+ground state is inhomogeneously modulated by orbital and charge solitons, i.e.
+narrow regions carrying charge (+/-)e/2, where the orbital arrangement varies
+very rapidly. So far, this has been only a theoretical prediction. Here, by
+using 139La Nuclear Magnetic Resonance (NMR) we provide direct evidence that
+the ground state of overdoped LCMO is indeed solitonic. By lowering temperature
+the narrow NMR spectra observed in the AFM phase are shown to wipe out, while
+for T<30K a very broad spectrum reappears, characteristic of an incommensurate
+(IC) charge and spin modulation. Remarkably, by further decreasing temperature,
+a relatively narrow feature emerges from the broad IC NMR signal, manifesting
+the formation of a solitonic modulation as T->0.",0910.4494v1
+2010-02-22,Quasiparticle Interference in the Unconventional Metamagnetic Compound Sr$_3$Ru$_2$O$_7$,"Quasiparticle interference (QPI) in spectroscopic imaging scanning tunneling
+microscopy provides a powerful method to detect orbital band structures and
+orbital ordering patterns in transition metal oxides. We use the $T$-matrix
+formalism to calculate the QPI spectra for the unconventional metamagnetic
+system of Sr$_3$Ru$_2$O$_7$ with a $t_{2g}$-orbital band structure. A detailed
+tight-binding model is constructed accounting for features such as spin-orbit
+coupling, bilayer splitting, and the staggered rotation of the RuO octahedra.
+The band parameters are chosen by fitting the calculated Fermi surfaces with
+those measured in the angular-resolved photo-emission spectroscopy experiment.
+The calculated quasiparticle interference at zero magnetic field exhibits a
+hollow square-like feature arising from the nesting of the quasi-1d $d_{xz}$
+and $d_{yz}$ orbital bands, in agreement with recent measurements by J. Lee
+{\it et al.} (Nature Physics {\bf 5}, 800 (2009)). Rotational symmetry breaking
+in the nematic metamagnetic state also manifests in the quasi-particle
+interference spectra.",1002.4079v5
+2010-06-02,"Electric and magnetic polarizabilities of hexagonal Ln2CuTiO6 (Ln=Y, Dy, Ho, Er and Yb)","We investigated the rare-earth transition metal oxide series, Ln2CuTiO6
+(Ln=Y, Dy, Ho, Er and Yb), crystallizing in the hexagonal structure with
+non-centrosymmetric P63cm space group for possible occurrences of multiferroic
+properties. Our results show that while these compounds, except Ln=Y, exhibit a
+low temperature antiferromagnetic transition due to the ordering of the
+rare-earth moments, the expected ferroelectric transition is frustrated by the
+large size difference between Cu and Ti at the B-site. Interestingly, this
+leads these compounds to attain a rare and unique combination of desirable
+paraelectric properties with high dielectric constants, low losses and weak
+temperature and frequency dependencies. First-principles calculations establish
+these exceptional properties result from a combination of two effects. A
+significant difference in the MO5 polyhedral sizes for M = Cu and M = Ti
+suppress the expected co-operative tilt pattern of these polyhedra, required
+for the ferroelectric transition, leading to relatively large values of the
+dielectric constant for every compound investigated in this series.
+Additionally, it is shown that the majority contribution to the dielectric
+constant arises from intermediate-frequency polar vibrational modes, making it
+relatively stable against any temperature variation. Changes in the temperature
+stability of the dielectric constant amongst different members of this series
+are shown to arise from changes in relative contributions from soft polar
+modes.",1006.0417v2
+2010-07-14,Combining DFT and Many-Body Methods to Understand Correlated Materials,"The electronic and magnetic properties of many strongly-correlated systems
+are controlled by a limited number of states, located near the Fermi level and
+well isolated from the rest of the spectrum. This opens a formal way for
+combining the methods of first-principles electronic structure calculations,
+based on the density-functional theory (DFT), with many-body models, formulated
+in the restricted Hilbert space of states close to the Fermi level. The core of
+this project is the so-called ""realistic modeling"" or the construction of the
+model many-body Hamiltonians entirely from the first principles. Such a
+construction should be able to go beyond the conventional local-density
+approximation (LDA), which typically supplements the density-functional theory,
+and incorporate the physics of Coulomb correlations. It should also provide a
+transparent physical picture for the low-energy properties of strongly
+correlated materials. In this review article, we will outline the basic ideas
+of such a realistic modeling. The entire procedure will be illustrated on the
+series of examples, including the distorted transition-metal perovskite oxides,
+the compounds with the inversion symmetry breaking caused by the defects, and
+the alkali hyperoxide KO2, which can be regarded as an analog of
+strongly-correlated systems where the localized electrons reside on the
+molecular orbitals of the O2- dimer. In order to illustrate abilities of the
+realistic modeling, we will also consider solutions of the obtained low-energy
+models for a number of systems, and argue that it can be used as a powerful
+tool for the exploration and understanding of properties of strongly correlated
+materials.",1007.2271v1
+2010-07-19,Intra-unit-cell electronic nematicity of the high-Tc copper-oxide pseudogap states,"In the high-transition-temperature (high-Tc) superconductors the pseudogap
+phase becomes predominant when the density of doped holes is reduced1. Within
+this phase it has been unclear which electronic symmetries (if any) are broken,
+what the identity of any associated order parameter might be, and which
+microscopic electronic degrees of freedom are active. Here we report the
+determination of a quantitative order parameter representing intra-unit-cell
+nematicity: the breaking of rotational symmetry by the electronic structure
+within CuO2 unit cell. We analyze spectroscopic-imaging scanning tunneling
+microscope images of the intra-unit-cell states in underdoped
+Bi2Sr2CaCu2O8+{\delta} and, using two independent evaluation techniques, find
+evidence for electronic nematicity of the states close to the pseudogap energy.
+Moreover, we demonstrate directly that these phenomena arise from electronic
+differences at the two oxygen sites within each unit cell. If the
+characteristics of the pseudogap seen here and by other techniques all have the
+same microscopic origin, this phase involves weak magnetic states at the O
+sites that break 90o -rotational symmetry within every CuO2 unit cell.",1007.3216v1
+2010-12-07,Pauli Spin Blockade in a Highly Tunable Silicon Double Quantum Dot,"Double quantum dots are convenient solid-state platforms to encode quantum
+information. Two-electron spin states can be conveniently detected and
+manipulated using strong quantum selection rules based on the Pauli exclusion
+principle, leading to the well-know Pauli spin blockade of electron transport
+for triplet states. Coherent spin states would be optimally preserved in an
+environment free of nuclear spins, which is achievable in silicon by isotopic
+purification. Here we report on a deliberately engineered, gate-defined silicon
+metal-oxide-semiconductor double quantum dot system. The electron occupancy of
+each dot and the inter-dot tunnel coupling are independently tunable by
+electrostatic gates. At weak inter-dot coupling we clearly observe Pauli spin
+blockade and measure a large intra-dot singlet-triplet splitting $>$ 1 meV. The
+leakage current in spin blockade has a peculiar magnetic field dependence,
+unrelated to electron-nuclear effects and consistent with the effect of
+spin-flip cotunneling processes. The results obtained here provide excellent
+prospects for realizing singlet-triplet qubits in silicon.",1012.1410v2
+2010-12-10,Pairing mechanism of high-temperature superconductivity: Experimental constraints,"Developing a theory of high-temperature superconductivity in copper oxides is
+one of the outstanding problems in physics. It is a challenge that has defeated
+theoretical physicists for more than twenty years. Attempts to understand this
+problem are hindered by the subtle interplay among a few mechanisms and the
+presence of several nearly degenerate and competing phases in these systems.
+Here we present some crucial experiments that place essential constraints on
+the pairing mechanism of high-temperature superconductivity. The observed
+unconventional oxygenisotope effects in cuprates have clearly shown strong
+electron-phonon interactions and the existence of polarons and/or bipolarons.
+Angle-resolved photoemission and tunneling spectra have provided direct
+evidence for strong coupling to multiple-phonon modes. In contrast, these
+spectra do not show strong coupling features expected for magnetic resonance
+modes. Angle-resolved photoemission spectra and the oxygen-isotope effect on
+the antiferromagnetic exchange energy J in undoped parent compounds
+consistently show that the polaron binding energy is about 2 eV, which is over
+one order of magnitude larger than J = 0.14 eV. The normal-state
+spin-susceptibility data of holedoped cuprates indicate that intersite
+bipolarons are the dominant charge carriers in the underdoped region while the
+component of Fermi-liquid-like polarons is dominant in the overdoped region.
+All the experiments to test the gap or order-parameter symmetry consistently
+demonstrate that the intrinsic gap (pairing) symmetry for the Fermi-liquid-like
+component is anisotropic s-wave and the order-parameter symmetry of the
+Bose-Einstein condensation of bipolarons is d-wave.",1012.2368v2
+2011-06-30,Hole spectral functions in lightly doped quantum antiferromagnets,"We study the hole and magnon spectral functions as a function of hole doping
+in the two-dimensional (2D) t-J and t-t'-t""-J models working within the limits
+of the spin-wave theory, by linearizing the hole-spin-deviation interaction and
+by adapting the non-crossing approximation (NCA). We find that the staggered
+magnetization decreases rather rapidly with doping and it goes to zero at a few
+percent of hole concentration in both t-J and the t-t'-t""-J model. We find that
+with doping, the residue of the quasiparticle peak at G=(pi/2,pi/2) decreases
+rapidly with doping and the spectral function is in agreement with high
+resolution angle-resolved photo-emission spectroscopy (ARPES) studies of the
+copper-oxide superconductors. The observed large shift of the chemical
+potential inside the Mott gap is found to be a result of broadening of the
+quasiparticle peak. We find pockets centered at G, similar to those observed by
+quantum oscillation measurements, (i) with an elliptical shape with large
+eccentricity along the anti-nodal direction in the case of the t-J model, and
+(ii) with an almost circular shape in the case of the t-t'-t""-J model. We also
+find that the spectral intensity distribution in the doped antiferromagnet has
+a waterfall-like patten along the nodal direction of the Brillouin zone, a
+feature that is also seen in ARPES measurements.",1106.6332v1
+2011-09-27,Boron Nitride Nanotubes as Templates for Half-Metal Nanowires,"We investigate by means of DFT/GGA+U calculations the electronic and
+structural properties of magnetic nanotubes composed of an iron oxide monolayer
+and (n,0) Boron Nitride (BN) nanotubes, with n ranging from 6 up to 14. The
+formation energy per FeO molecule of FeO covered tubes is smaller than the
+formation energy of small FeO nanoparticles which suggest that the FeO
+molecules may cover the BN nanotubes rather than to aggregate to form the FeO
+bulk. We propose a continuous model for the FeO covered BN nanotubes formation
+energy which predicts that BN tubes with diameter of roughly 13 \AA are the
+most stable. Unlike carbon nanotubes, the band structure of FeO covered BN
+nanotubes can not be obtained by slicing the band structure of a FeO layer, the
+curvature and the interaction with the BN tube is determinant for the
+electronic behavior of FeO covered tubes. As a result the tubes are
+semiconductors, intrinsic half-metals or semi-half-metals that can become
+half-metals charged with either electrons and holes. Such a result may be
+important in the spintronics context.",1109.5936v1
+2011-10-27,Effect of spin relaxation rate on the interfacial spin depolarization in ferromagnet/oxide/semiconductor contacts,"Combined measurements of normal and inverted Hanle effects in
+CoFe/MgO/semiconductor (SC) contacts reveal the effect of spin relaxation rate
+on the interfacial spin depolarization (ISD) from local magnetic fields.
+Despite the similar ferromagnetic electrode and interfacial roughness in both
+CoFe/MgO/Si and CoFe/MgO/Ge contacts, we have observed clearly different
+features of the ISD depending on the host SC. The precession and relaxation of
+spins in different SCs exposed to the local fields from more or less the same
+ferromagnets give rise to a notably different ratio of the inverted Hanle
+signal to the normal one. At room temperature, a large ISD is observed in the
+CoFe/MgO/Si contact, but a small ISD in the CoFe/MgO/Ge contact. The ISD of the
+CoFe/MgO/Ge contact has been substantially increased at low temperature. These
+results can be ascribed to the difference of spin relaxation in host SCs. A
+model calculation of the ISD, considering the spin precession due to the local
+field and the spin relaxation in the host SC, explains the temperature and bias
+dependence of the ISD consistently.",1110.5978v2
+2011-11-30,Semimetal and Topological Insulator in Perovskite Iridates,"The two-dimensional layered perovskite Sr2IrO4 was proposed to be a
+spin-orbit Mott insulator, where the effect of Hubbard interaction is amplified
+on a narrow J_{eff} = 1/2 band due to strong spin-orbit coupling. On the other
+hand, the three-dimensional orthorhombic perovskite (Pbnm) SrIrO3 remains
+metallic. To understand the physical origin of the metallic state and possible
+transitions to insulating phases, we construct a tight-binding model for
+SrIrO3. The band structure possesses a line node made of J_{eff} = 1/2 bands
+below the Fermi level. As a consequence, instability towards magnetic ordering
+is suppressed and the system remains metallic. This line node, originating from
+the underlying crystal structure, turns into a pair of three-dimensional nodal
+points on the introduction of a staggered potential or spin-orbit coupling
+strength between alternating layers. Increasing this potential beyond a
+critical strength induces a transition to a strong topological insulator,
+followed by another transition to a normal band insulator. We propose that
+materials constructed with alternating Ir- and Rh-oxide layers along the (001)
+direction, such as Sr2IrRhO6, are candidates for a strong topological
+insulator.",1112.0015v2
+2011-12-21,"Resonant soft x-ray scattering, stripe order, and the electron spectral function in cuprates","We review the current state of efforts to use resonant soft x-ray scattering
+(RSXS), which is an elastic, momentum-resolved, valence band probe of strongly
+correlated electron systems, to study stripe-like phenomena in copper-oxide
+superconductors and related materials. We review the historical progress
+including RSXS studies of Wigner crystallization in spin ladder materials,
+stripe order in 214-phase nickelates, 214-phase cuprates, and other systems.
+  One of the major outstanding issues in RSXS concerns its relationship to more
+established valence band probes, namely angle-resolved photoemission (ARPES)
+and scanning tunneling microscopy (STM). These techniques are widely understood
+as measuring a one-electron spectral function, yet a relationship between RSXS
+and a spectral function has so far been unclear. Using physical arguments that
+apply at the oxygen $K$ edge, we show that RSXS measures the square modulus of
+an advanced version of the Green's function measured with STM. This indicates
+that, despite being a momentum space probe, RSXS is more closely related to STM
+than to ARPES techniques.
+  Finally, we close with some discussion of the most promising future
+directions for RSXS. We will argue that the most promising area lies in high
+magnetic field studies, particularly of edge states in strongly correlated
+heterostructures, and the vortex state in superconducting cuprates, where RSXS
+may clarify the anomalous periodicities observed in recent quantum oscillation
+experiments.",1112.5112v2
+2012-09-20,Virtual Synthesis of Nanoscale Systems with Pre-Designed Properties: Fundamentals and Applications. Chapter 7. Nickel Oxide Quantum Dots and Polymer Nanowires,"The virtual (i.e., fundamental many body quantum theory-based, computational)
+synthesis method is used to establish electronic templates of about 30
+non-stoichiometric nanosystems composed of nickel and oxygen atoms and ranging
+from about 6 {\AA} to 6 nm in linear dimensions. Flexible and stretchable Ni-O
+bond in such structures accommodates various ratios of Ni to O atoms, and both
+antiferromagnetic and ferromagnetic spin alignments. Depending on synthesis
+conditions, smaller Ni-O quantum dots (QDs) composed of up to 14 atoms or so
+may have both types of spin alignments, while quantum-confined, quasi one
+dimensional Ni-O nanowires (QWs) appear to be nanopolymers with
+antiferromagnetic spin alignment. Ni-O bond flexibility and related ease of
+spin re-arrangement may facilitate physical mechanisms leading to the
+development or loss of exchange bias when such Ni-O quantum dots and wires
+(QDWs) interact with surfaces or each other at some thermochemical conditions.
+These structural and compositional flexibility is reflected by QDWs' molecular
+electrostatic potential (MEP) and electronic level structure (ELS). In
+particular, the direct optical transition energy (OTE) of the studied Ni-O
+systems may vary within an order of magnitude, and their electronic and
+magnetic properties can be finely tuned to match applications requirements by
+manipulations with synthesis conditions, the structure and composition of
+quantum confinement. The developed electronic templates are available upon
+request.",1209.4666v1
+2012-10-25,Effect of high temperature heat treatments on the quality factor of a large-grain superconducting radio-frequency niobium cavity,"Large-grain Nb has become a viable alternative to fine-grain Nb for the
+fabrication of superconducting radio-frequency cavities. In this contribution
+we report the results from a heat treatment study of a large-grain 1.5 GHz
+single-cell cavity made of ""medium purity"" Nb. The baseline surface preparation
+prior to heat treatment consisted of standard buffered chemical polishing. The
+heat treatment in the range 800 - 1400 C was done in a newly designed vacuum
+induction furnace. Q0 values of the order of 2x1010 at 2.0 K and peak surface
+magnetic field (Bp) of 90 mT were achieved reproducibly. A Q0-value of
+(5+-1)1010 at 2.0 K and Bp = 90 mT was obtained after heat treatment at 1400 C.
+This is the highest value ever reported at this temperature, frequency and
+field. Samples heat treated with the cavity at 1400 C were analyzed by
+secondary ion mass spectrometry, secondary electron microscopy, energy
+dispersive X-ray, point contact tunneling and X-ray diffraction and revealed a
+complex surface composition which includes titanium oxide, increased carbon and
+nitrogen content but reduced hydrogen concentration compared to a non
+heat-treated sample.",1210.6875v4
+2012-11-14,Synthesis of Homogeneous Manganese-Doped Titanium Oxide Nanotubes from Titanate Precursors,"We report a novel synthesis route of homogeneously manganese-doped titanium
+dioxide nanotubes in a broad concentration range. The scroll-type trititanate
+(H(2)Ti(3)O(7)) nanotubes prepared by hydrothermal synthesis were used as
+precursors. Mn2+ ions were introduced by an ion exchange method resulting
+Mn(x)H(2-x)Ti(3)O(7). In a subsequent heat-treatment they were transformed into
+Mn(y)Ti(1-y)O(2) where y=x/(3+x). The state and the local environment of the
+Mn2+ ions in the precursor and final products were studied by Electron Spin
+Resonance (ESR) technique. It was found that the Mn2+ ions occupy two
+positions: the first having an almost perfect cubic symmetry while the other is
+in a strongly distorted octahedral site. The ratio of the two Mn2+ sites is
+independent of the doping level and amounts to 15:85 in Mn(x)H(2-x)Ti(3)O(7)
+and to 5:95 in Mn(y)Ti(1-y)O(2). SQUID magnetometry does not show long-range
+magnetic order in the homogeneously Mn2+-doped nanotubes.",1211.3459v2
+2013-03-20,Performance of Titanium-Oxide/Polymer Insulation in Bi-2212/Ag-alloy Round Wire Wound Superconducting Coils,"Conductor insulation is one of the key components needed to make Ag-alloy
+clad Bi2Sr2CaCu2O8+x (Bi-2212/Ag) superconducting round wire (RW) successful
+for high field magnet applications as dielectric standoff and high winding
+current densities (Jw) directly depend on it. In this study, a TiO2/polymer
+insulation coating developed by nGimat LLC was applied to test samples and a
+high field test coil. The insulation was investigated by differential thermal
+analysis (DTA), thermo-gravimetric analysis (TGA), scanning electron microscopy
+(SEM), dielectric properties measurement, and transport critical current (Ic)
+properties measurement. About 29% of the insulation by weight is polymer. When
+the Bi-2212/Ag wire is full heat treated, this decomposes with slow heating to
+400{\deg}C in pure O2. After the full reaction, we found that the TiO2 did not
+degrade the critical current properties, adhered well to the conductor, and
+provided a breakdown voltage of >100 V, which allowed the test coil to survive
+quenching in 31.2 T background field, while providing a 2.6 T field increment.
+For Bi-2212/Ag RW with a typical diameter of 1.0-1.5 mm, this ~15 um thick
+insulation allows a very high coil packing factor of ~0.74, whereas earlier
+alumino-silicate braid insulation only allows packing factors of 0.38-0.48.",1303.4810v1
+2013-03-28,Microscopic and Spectroscopic Evidence for a Slater Metal-Insulator Transition in Sr2IrO4,"Layered 5d transition metal oxides (TMOs) have attracted significant interest
+in recent years because of the rich physical properties induced by the
+interplay between spin-orbit coupling, bandwidth and on-site Coulomb repulsion.
+In Sr2IrO4, this interplay opens a gap near the Fermi energy and stabilizes a
+Jeff=1/2 spin-orbital entangled insulating state at low temperatures. Whether
+this metal-insulating transition (MIT) is Mott-type (electronic-correlation
+driven) or Slater-type (magnetic-order driven) has been under intense debate.
+We address this issue via spatially resolved imaging and spectroscopic studies
+of the Sr2IrO4 surface using scanning tunneling microscopy/spectroscopy
+(STM/S). The STS results clearly illustrate the opening of the (~150-250 meV)
+insulating gap at low temperatures, in qualitative agreement with our
+density-functional theory (DFT) calculations. More importantly, the measured
+temperature dependence of the gap width coupled with our DFT+dynamical mean
+field theory (DMFT) results strongly support the Slater-type MIT scenario in
+Sr2IrO4. The STS data further reveal a pseudogap structure above the Neel
+temperature, presumably related to the presence of antiferromagnetic
+fluctuations.",1303.7265v2
+2013-05-17,Onsager's Wien Effect on a Lattice,"The Second Wien Effect describes the non-linear, non-equilibrium response of
+a weak electrolyte in moderate to high electric fields. Onsager's 1934
+electrodiffusion theory along with various extensions has been invoked for
+systems and phenomena as diverse as solar cells, surfactant solutions, water
+splitting reactions, dielectric liquids, electrohydrodynamic flow, water and
+ice physics, electrical double layers, non-Ohmic conduction in semiconductors
+and oxide glasses, biochemical nerve response and magnetic monopoles in spin
+ice. In view of this technological importance and the experimental ubiquity of
+such phenomena, it is surprising that Onsager's Wien effect has never been
+studied by numerical simulation. Here we present simulations of a lattice
+Coulomb gas, treating the widely applicable case of a double equilibrium for
+free charge generation. We obtain detailed characterisation of the Wien effect
+and confirm the accuracy of the analytical theories as regards the field
+evolution of the free charge density and correlations. We also demonstrate that
+simulations can uncover further corrections, such as how the field-dependent
+conductivity may be influenced by details of microscopic dynamics. We conclude
+that lattice simulation offers a powerful means by which to investigate
+system-specific corrections to the Onsager theory, and thus constitutes a
+valuable tool for detailed theoretical studies of the numerous practical
+applications of the Second Wien Effect.",1305.4072v2
+2013-05-17,"Spins, Stripes, and Superconductivity in Hole-Doped Cuprates","One of the major themes in correlated electron physics over the last quarter
+century has been the problem of high-temperature superconductivity in
+hole-doped copper-oxide compounds. Fundamental to this problem is the
+competition between antiferromagnetic spin correlations, a symptom of strong
+Coulomb interactions, and the kinetic energy of the doped carriers, which
+favors delocalization. After discussing some of the early challenges in the
+field, I describe the experimental picture provided by a variety of
+spectroscopic and transport techniques. Then I turn to the technique of neutron
+scattering, and discuss how it is used to determine spin correlations,
+especially in model systems of quantum magnetism. Neutron scattering and
+complementary techniques have determined the extent to which antiferromagnetic
+spin correlations survive in the cuprate superconductors. One experimental case
+involves the ordering of spin and charge stripes. I first consider related
+measurements on model compounds, such as La(2-x)Sr(x)NiO(4+d), and then discuss
+the case of La(2-x)Ba(x)CuO(4). In the latter system, recent transport studies
+have demonstrated that quasi-two-dimensional superconductivity coexists with
+the stripe order, but with frustrated phase order between the layers. This has
+led to new concepts for the coexistence of spin order and superconductivity.
+While the relevance of stripe correlations to high-temperature
+superconductivity remains a subject of controversy, there is no question that
+stripes are an intriguing example of electron matter that results from strong
+correlations.",1305.4118v1
+2013-10-17,Insights into the Phase Diagram of Bismuth Ferrite from Quasi-Harmonic Free Energy Calculations,"We have used first-principles methods to investigate the phase diagram of
+multiferroic bismuth ferrite (BiFeO3 or BFO), revealing the energetic and
+vibrational features that control the occurrence of various relevant
+structures. More precisely, we have studied the relative stability of four
+low-energy BFO polymorphs by computing their free energies within the
+quasi-harmonic approximation, introducing a practical scheme that allows us to
+account for the main effects of spin disorder. As expected, we find that the
+ferroelectric ground state of the material (with R3c space group) transforms
+into an orthorhombic paraelectric phase (Pnma) upon heating. We show that this
+transition is not significantly affected by magnetic disorder, and that the
+occurrence of the Pnma structure relies on its being vibrationally (although
+not elastically) softer than the R3c phase. We also investigate a
+representative member of the family of nano-twinned polymorphs recently
+predicted for BFO [Prosandeev et al., Adv. Funct. Mater. 23, 234 (2013)] and
+discuss their possible stabilization at the boundaries separating the R3c and
+Pnma regions in the corresponding pressure-temperature phase diagram. Finally,
+we elucidate the intriguing case of the so-called super-tetragonal phases of
+BFO: Our results explain why such structures have never been observed in the
+bulk material, despite their being stable polymorphs of very low energy.
+Quantitative comparison with experiment is provided whenever possible, and the
+relative importance of various physical effects (zero-point motion, spin
+fluctuations, thermal expansion) and technical features (employed
+exchange-correlation energy density functional) is discussed. Our work attests
+the validity and usefulness of the quasi-harmonic scheme to investigate the
+phase diagram of this complex oxide, and prospective applications are
+discussed.",1310.4703v1
+2013-11-25,Theory of nodal s+- wave pairing symmetry in the Pu-based 115 superconductor family,"The spin-fluctuation mechanism of superconductivity usually results in the
+presence of gapless or nodal quasiparticle states in the excitation spectrum.
+Nodal quasiparticle states are well established in copper-oxide, and
+heavy-fermion superconductors, but not in iron-based superconductors. Here, we
+study the pairing symmetry and mechanism of a new class of plutonium-based
+high-Tc superconductors and predict the presence of a nodal $s^{+-}$ wave
+pairing symmetry in this family. Starting from a density-functional theory
+(DFT) based electronic structure calculation we predict several
+three-dimensional (3D) Fermi surfaces in this 115 superconductor family. We
+identify the dominant Fermi surface ``hot-spots' in the inter-band scattering
+channel, which are aligned along the wavevector ${\bf Q}\sim(\pi,\pi,\pi)$,
+where degeneracy could induce sign-reversal of the pairing symmetry. Our
+calculation demonstrates that the $s^{+-}$ wave pairing strength is stronger
+than the previously thought $d$-wave pairing; and more importantly, this
+pairing state allows for the existence of nodal quasiparticles. Finally, we
+predict the shape of the momentum- and energy-dependent magnetic resonance
+spectrum for the identification of this pairing symmetry.",1311.6410v2
+2013-11-26,Local Reconstructions of Silicene Induced by Adatoms,"The interaction of silicene with Si, C, H, O, Ti atoms along with H$_2$,
+H$_2$O and O$_2$ molecules are investigated and the induced functionalities
+thereof are analyzed using first principles density functional theory. Si
+adatom initially adsorbed at the top site of silicene pushes down the Si atom
+underneath to form a dumbbell like structure with 3+1 coordination. This
+prediction is important for silicene research and reveal new physical phenomena
+related with the formation of multilayer Si, which is apparently the precursor
+state for missing layered structure of silicon. We found that dumbbell
+structure attributes coverage dependent electronic and magnetic properties to
+nonmagnetic bare silicene. Even more interesting is that silicene with
+dumbbells is energetically more favorable than the pristine silicene: The more
+dense the dumbbell coverage, the stronger is the cohesion. Incidentally, these
+structures appear to be intermediate between between silicene and silicon.
+Carbon adatom, which is initially adsorbed to the bridge position, substitutes
+one Si atom, if it overcomes a small energy barrier. Oxygen molecule can
+dissociate on silicene surface, whereby constituent oxygen atoms oxidize
+silicene by forming strong bonds. By varying the concentration and decoration
+of carbon, hydrogen and oxygen atoms one can tune the band gap of silicene.
+Through the adsorption of hydrogen or titanium adatom, silicene acquires spin
+polarized state. A half metallic ferromagnetic behavior is attained at specific
+uniform coverage of Ti adatom, which may function as a spin valve.",1311.6657v1
+2014-04-24,Competition between heavy-fermion and Kondo interaction in isoelectronic A-site ordered perovskites,"With current research efforts shifting towards the 4$d$ and 5$d$ transition
+metal oxides, understanding the evolution of the electronic and magnetic
+structure as one moves away from 3$d$ materials is of critical importance. Here
+we perform X-ray spectroscopy and electronic structure calculations on $A$-site
+ordered perovskites with Cu in the $A$-site and the $B$-sites descending along
+the 9th group of the periodic table to elucidate the emerging properties as
+$d$-orbitals change from partially filled 3$d$, 4$d$, to 5$d$. The results show
+that when descending from Co to Ir the charge transfers from the cuprate like
+Zhang-Rice state on Cu to the t$_{2g}$ orbital of the B site. As the Cu
+$d$-orbital occupation approaches the Cu$^{2+}$ limit, a mixed-valence state in
+CaCu$_3$Rh$_4$O$_{12}$ and heavy fermion state in CaCu$_3$Ir$_4$O$_{12}$ are
+obtained. The investigated d-electron compounds are mapped onto the Doniach
+phase diagram of the competing RKKY and Kondo interactions developed for
+f-electron systems.",1404.6137v4
+2014-08-14,Iron based superconductors: A brief overview,"Fe-based superconductors were discovered in 2008. This discovery with T$_c$
+values up to 56 K, generated a new belief in the field of superconductivity.
+Till its discovery, high temperature superconductivity in cuprates, created a
+prejudice that Cu-oxides are essential building blocks for a high temperature
+superconducting material. These Fe based superconductors do not contain Cu-O
+planes (some of the materials are even O free). It will be argued in this
+review, that these iron pnictide and chalcogenide (FePn/Ch) superconductors
+have Fe electrons at the Fermi surface together with an unusual Fermiology that
+can change rapidly with doping. This may lead to very different normal and
+superconducting state properties compared to those in standard electron-phonon
+coupled {\it conventional} superconductors. There are a large number of
+evidences showing that superconductivity, magnetism, orbital fluctuations are
+intimately related and coexist in these materials although the mechanism of
+superconductivity in these compounds is still unknown. The electronic specific
+heat, $\frac{2\Delta}{k_B T_c}$ ratio, phase diagrams, isotope effect, crystal
+structures and there correlation to T$_c$ from various available experimental
+data are main inputs of this review to show the above.",1408.3244v1
+2014-10-12,"Spin-orbit coupling, strong correlation, and insulator-metal transitions: the J$_{\rm eff}$ =3\2 ferromagnetic Mott insulator Ba$_{2}$NaOsO$_{6}$","The double perovskite Ba$_{2}$NaOsO$_{6}$ (BNOO), an exotic example of a very
+high oxidation state (heptavalent) osmium $d^1$ compound and also uncommon by
+being a ferromagnetic Mott insulator without Jahn-Teller (JT) distortion, is
+modeled using the density functional theory (DFT) hybrid functional based exact
+exchange for correlated electrons (oeeHyb) method and including spin-orbit
+coupling (SOC). The experimentally observed narrow gap ferromagnetic insulating
+ground state is obtained, with easy axis along [110] in accord with experiment,
+providing support that this approach provides a realistic method for studying
+this system. The predicted spin density for [110] spin orientation is nearly
+cubic (unlike for other directions), providing an explanation for the absence
+of JT distortion. An orbital moment of -0.4$\mu_B$ strongly compensates the
++0.5$\mu_B$ spin moment on Os, leaving a strongly compensated moment more in
+line with experiment. Remarkably, the net moment lies primarily on the oxygen
+ions. An insulator-metal transition by rotating the magnetization direction
+with an external field under moderate pressure is predicted as one consequence
+of strong SOC, and metallization under moderate pressure is predicted.
+Comparison is made with the isostructural, isovalent insulator Ba$_2$LiOsO$_6$
+which however orders antiferromagnetically.",1410.3167v1
+2014-10-20,Al/AlO$_{\rm {x}}$/Al-Josephson-junction-based microwave generators for weak-signal applications below 100 mK,"An application-specific Josephson generator is being developed as an on-chip
+calibration source for single-microwave-photon detectors operating below $T
+\sim $100 mK in the frequency range from 110 to 170 GHz. The targeted
+calibration power corresponds to the photon detection rate of 0.01 to 10 counts
+per second. We analyze the Josephson oscillations within the framework of the
+tunnel junction microscopic (TJM) model and find the corrections to be made to
+a standard RSJ model of the junction, operating as a quasi-monochromatic source
+of microwaves. Experimentally, we implemented a number of aluminium-based
+two-junction interferometers connected to the leads via microstripline
+resistors made of partly oxidized titanium films. The $I$-$V$ curves exhibit a
+behaviour ensuring generation of the microwave signal in the frequency range
+required. By setting the biasing point $\bar{V}$ and applying the magnetic
+field, one can tune the generator's frequency and power, respectively. A small
+oscillation linewidth, down to a few GHz, and a low level of black-body
+radiation emitted by hot parts of the circuit are predicted, using the
+experimental parameters.",1410.5314v1
+2014-10-27,Scaling behavior of the thermopower of the archetypical heavy-fermion metal $\rm{YbRh_2Si_2}$,"We reveal and explain a scaling behavior of the thermopower $S/T$ exhibiting
+by the archetypical heavy-fermion (HF) metal $\rm{YbRh_2Si_2}$ under the
+application of magnetic field $B$ at temperatures $T$. We show that the same
+scaling is demonstrated by such different HF compounds as $\beta$-${\rm
+YbAlB_4}$ and the strongly correlated layered cobalt oxide $\rm
+[BiBa_{0.66}K_{0.36}O_{2}]CoO_{2}$. Using $\rm{YbRh_2Si_2}$ as an example, we
+demonstrate that the scaling behavior of $S/T$ is violated at the
+antiferromagnetic phase transition, while both the residual resistivity
+$\rho_0$ and the density of states $N$ experience jumps at the phase
+transition, making the thermopower experience two jumps and change its sign.
+Our elucidation is based on flattening of the single-particle spectrum that
+profoundly affects $\rho_0$ and $N$. To depict the main features of the $S/T$
+behavior, we construct the $T-B$ schematic phase diagram of $\rm{YbRh_2Si_2}$.
+Our calculated $S/T$ for the HF compounds are in good agreement with
+experimental facts and support our observations.",1410.7299v4
+2014-12-02,Exploring intertwined orders in cuprate superconductors,"The concept of intertwined orders has been introduced to describe the
+cooperative relationship between antiferromagnetic spin correlations and
+electron (or hole) pair correlations that develop in copper-oxide
+superconductors. This contrasts with systems in which, for example,
+charge-density-wave (CDW) order competes for Fermi surface area with
+superconductivity. La$_{2-x}$Ba$_x$CuO$_4$ with $x=0.125$ provides an example
+in which the ordering of spin stripes coincides with the onset of
+two-dimensional superconducting correlations. The apparent frustration of the
+interlayer Josephson coupling has motivated the concept of the
+pair-density-wave superconductor, a state that theoretical calculations show to
+be energetically competitive with the uniform $d$-wave superconductor. Even at
+$x=0.095$, where there is robust superconductivity below 32~K in zero field,
+the coexistence of strong, low-energy, incommensurate spin excitations implies
+a spatially modulated and intertwined pair wave function. Recent observations
+of CDW order in YBa$_2$Cu$_3$O$_{6+x}$ and other cuprate families have raised
+interesting questions regarding the general role of charge modulations and the
+relation to superconductivity. While there are differences in the doping
+dependence of the modulation wave vectors in YBa$_2$Cu$_3$O$_{6+x}$ and
+La$_{2-x}$Ba$_x$CuO$_4$, the maximum ordering strength is peaked at the hole
+concentration of 1/8 in both cases. There are also possible connections with
+the quantum oscillations that have been detected about the same hole
+concentration but at high magnetic fields. Resolving these relationships
+remains a research challenge.",1412.1011v1
+2015-01-29,Interface observation of heat-treated Co/Mo2C multilayers,"We study the interface evolution of a series of periodic Co/Mo2C multilayers
+as a function of the annealing temperature up to 600{\textdegree}C. Different
+complementary techniques are implemented to get information on the phenomenon
+taking place at the interfaces of the stack. The periodical structure of
+Co/Mo2C multilayer is proven by Time-of-flight secondary ion mass spectrometry
+(ToF-SIMS) depth profiles which demonstrate the formation of an oxide layer at
+both air/stack and stack/substrate interfaces. From Nuclear magnetic resonance
+(NMR) spectra, we observed the intermixing phenomenon of Co and C atoms for the
+as-deposited sample, and then at annealing temperature above 300{\textdegree}C
+Co and C atoms separate from their mixed regions. Comparison of NMR results
+between Co/Mo 2 C and Co/C references confirms this phenomenon. This is in
+agreement with x-ray emission spectroscopy (XES) measurements. Furthermore the
+calculation of the Co-C, Co-Mo and Mo-C mixing enthalpy using Miedema's model
+gives a proof of the demixing of Co and C atoms present within the stacks above
+300{\textdegree}C. From the transmission electron microscopy (TEM) analysis, we
+found the presence of some crystallites within the as-deposited sample as well
+as the mainly amorphous nature of all layers. This is confirmed using x-ray
+diffraction (XRD) patterns which also demonstrate the growth of crystallites
+induced upon annealing.",1501.07360v1
+2015-03-12,High On/Off Ratio Memristive Switching of Manganite-Cuprate Bilayer by Interfacial Magnetoelectricity,"Memristive switching serves as the basis for a new generation of electronic
+devices. Memristors are two-terminal devices in which the current is turned on
+and off by redistributing point defects, e.g., vacancies, which is difficult to
+control. Memristors based on alternative mechanisms have been explored, but
+achieving both the high On/Off ratio and the low switching energy desirable for
+use in electronics remains a challenge. Here we report memristive switching in
+a La0.7Ca0.3MnO3/PrBa2Cu3O7 bilayer with an On/Off ratio greater than 10^3 and
+demonstrate that the phenomenon originates from a new type of interfacial
+magnetoelectricity. Using results from first-principles calculations, we show
+that an external electric-field induces subtle displacements of the interfacial
+Mn ions, which switches on/off an interfacial magnetic ""dead"" layer, resulting
+in memristive behavior for spin-polarized electron transport across the
+bilayer. The interfacial nature of the switching entails low energy cost about
+of a tenth of atto Joule for write/erase a ""bit"". Our results indicate new
+opportunities for manganite/cuprate systems and other transition-metal-oxide
+junctions in memristive applications.",1503.03601v1
+2015-06-03,Development of hard x-ray photoelectron SPLEED-based spectrometer applicable for probing of buried magnetic layer valence states,"A novel design of high-voltage compatible polarimeter for spin-resolved hard
+x-ray photoelectron spectroscopy (Spin-HAXPES) went into operation at beamline
+BL09XU of SPring-8 in Hyogo, Japan. The detector is based on the
+well-established principle of electron diffraction from a W(001) single-crystal
+at a scattering energy of 103.5 eV. Its special feature is that it can be
+operated at a high negative bias potential up to 10 kV, necessary to access the
+HAXPES range. The polarimeter is operated behind a large hemispherical analyzer
+(Scienta R-4000). It was optimized for high transmission of the transfer
+optics. The exit plane of the analyzer contains a delay-line detector (20 mm
+dia.) for conventional multichannel intensity spectroscopy simultaneously with
+single-channel spin analysis. The performance of the combined setup is
+demonstrated by the first spin-resolved data for the valence-region of a FeCo
+functional layer of a tunneling device, buried beneath 3 nm of oxidic material.
+The well-structured spin polarization spectrum validates Spin-HAXPES in the
+valence energy range as powerful method for bulk electronic structure analysis.
+The spin polarization spectrum exhibits a rich structure, originating from
+clearly discernible transitions in the majority and minority partial spin
+spectra.",1506.01356v1
+2015-06-29,Strain Doping: Reversible Single-Axis Control of a Complex Oxide Lattice via Helium Implantation,"We report on the use of helium ion implantation to independently control the
+out-of-plane lattice constant in epitaxial La0.7Sr0.3MnO3 thin films without
+changing the in-plane lattice constants. The process is reversible by a vacuum
+anneal. Resistance and magnetization measurements show that even a small
+increase in the out-of-plane lattice constant of less than 1% can shift the
+metal-insulator transition and Curie temperatures by more than 100 {\deg}C.
+Unlike conventional epitaxy-based strain tuning methods which are constrained
+not only by the Poisson effect but by the limited set of available substrates,
+the present study shows that strain can be independently and continuously
+controlled along a single axis. This permits novel control over orbital
+populations through Jahn-Teller effects, as shown by Monte Carlo simulations on
+a double-exchange model. The ability to reversibly control a single lattice
+parameter substantially broadens the phase space for experimental exploration
+of predictive models and leads to new possibilities for control over materials'
+functional properties.",1506.08659v1
+2015-09-10,Metal insulator transition and magnetotransport anomalies in perovskite SrIr0.5Ru0.5O3 thin films,"We investigated the nature of transport and magnetic properties in
+SrIr0.5Ru0.5O3, (SIRO) which has characteristics intermediate between a
+correlated non-Fermi liquid state and an itinerant Fermi liquid state, by
+growing perovskite thin films on various substrates (SrTiO3 (001),
+(LaAlO3)0.3(Sr2TaAlO6)0.7 (001) and LaAlO3 (001)). We observed systematic
+variation of underlying substrate dependent metal-to-insulator transition
+temperatures at 80 K on SrTiO3, 90 K on (LaAlO3)0.3(Sr2TaAlO6)0.7 and 100 K on
+LaAlO3) in resistivity. Resistivity in the metallic region follows a T3/2 power
+law; whereas insulating nature at low T is due to the localization effect.
+Magnetoresistance (MR) measurement of SIRO on SrTiO3 (001) shows negative MR
+upto 25 K and positive MR above 25 K, with negative MR proportional to B1/2 and
+positive MR proportional to B2; consistent with the localized-to-normal
+transport crossover dynamics. Furthermore, observed spin glass like behavior of
+SIRO on SrTiO3 (001) in the localized regime, validates the hypothesis that
+(Anderson) localization favors glassy ordering. These remarkable features
+provide a promising approach for future applications and of fundamental
+interest in oxide thin films.",1509.02990v1
+2015-11-22,Review of Spin Orbit Coupled Semimetal SrIrO3 in thin film form,"Spin orbit coupling provides a mechanism to lock the momentum of electron to
+its spin degree, recent years was revealed to be essential in arousing many
+novel physical behaviors. SrIrO3 is a typical metallic member of the strong
+spin orbit coupling iridate family. Its orthorhombic phase was confirmed as a
+particular spin orbit coupling assistant electron correlated semimetal with
+small electron and hole pockets, and was supposed to host versatile topological
+phases, with prospect of opening a new topological matter field based on
+oxides. The existing experiments have demonstrated that orthorhombic SrIrO3 can
+be easily synthesized at two dimensional scale films under the substrate
+lattice constraint, and the films display Fermi-liquid behavior in high
+temperature and generally two dimensional weak localization resulted metal
+insulator transition. The properties of orthorhombic SrIrO3 film are sensitive
+to the rotation and tilting angle, as well as the interlayer coupling of the
+IrO6 octahedras, consequently can be tuned through substrate strain engineering
+and size scale. For example, the film was approached a state similar to Sr2IrO4
+at the ultrathin limit to several unit cell, becoming a canted
+antiferromagnetic semiconductor/insulator. The existing knowledges suggest
+urgent demands of researches on the superlattices constructed with orthorhombic
+SrIrO3, for further understanding the evolution mechanism of the electron
+structure, and so the relevant magnetic state and topological phases in the
+orthorhombic SrIrO3 and its family.",1511.06979v2
+2016-01-20,"Mechanism, time-reversal symmetry and topology of superconductivity in noncentrosymmetric systems","We analyze the possible interaction-induced superconducting instabilities in
+noncentrosymmetric systems based on symmetries of the normal state. It is
+proven that pure electron-phonon coupling will always lead to a fully gapped
+superconductor that does not break time-reversal symmetry and is topologically
+trivial. We show that topologically nontrivial behavior can be induced by
+magnetic doping without gapping out the resulting Kramers pair of Majorana edge
+modes. In case of superconductivity arising from the particle-hole fluctuations
+associated with a competing instability, the properties of the condensate
+crucially depend on the time-reversal behavior of the order parameter of the
+competing instability. When the order parameter preserves time-reversal
+symmetry, we obtain exactly the same properties as in case of phonons. If it is
+odd under time-reversal, the Cooper channel of the interaction will be fully
+repulsive leading to sign changes of the gap and making spontaneous
+time-reversal symmetry breaking possible. To discuss topological properties, we
+focus on fully gapped time-reversal symmetric superconductors and derive
+constraints on possible pairing states that yield necessary conditions for the
+emergence of topologically nontrivial superconductivity. These conditions might
+serve as a tool in the search for topological superconductors. We also discuss
+implications for oxides heterostructures and single-layer FeSe.",1601.05459v1
+2016-02-10,Superconductor Digital Electronics: Scalability and Energy Efficiency Issues,"Superconductor digital electronics using Josephson junctions as ultrafast
+switches and magnetic-flux encoding of information was proposed over 30 years
+ago as a sub-terahertz clock frequency alternative to semiconductor electronics
+based on complementary metal-oxide-semiconductor (CMOS) transistors. Recently,
+interest in developing superconductor electronics has been renewed due to a
+search for energy saving solutions in applications related to high-performance
+computing. The current state of superconductor electronics and fabrication
+processes are reviewed in order to evaluate whether this electronics is
+scalable to a very large scale integration (VLSI) required to achieve
+computation complexities comparable to CMOS processors. A fully planarized
+process at MIT Lincoln Laboratory, perhaps the most advanced process developed
+so far for superconductor electronics, is used as an example. The process has
+nine superconducting layers: eight Nb wiring layers with the minimum feature
+size of 350 nm, and a thin superconducting layer for making compact
+high-kinetic-inductance bias inductors. All circuit layers are fully planarized
+using chemical mechanical planarization (CMP) of SiO2 interlayer dielectric.
+The physical limitations imposed on the circuit density by Josephson junctions,
+circuit inductors, shunt and bias resistors, etc., are discussed. Energy
+dissipation in superconducting circuits is also reviewed in order to estimate
+whether this technology, which requires cryogenic refrigeration, can be energy
+efficient. Fabrication process development required for increasing the density
+of superconductor digital circuits by a factor of ten and achieving densities
+above 10^7 Josephson junctions per cm^2 is described.",1602.03546v2
+2016-02-25,Phase diagram and collective excitation in excitonic insulator: from the orbital physics viewpoint,"Excitonic insulating system is studied from the viewpoints of the orbital
+physics in strongly correlated electron systems. An effective model Hamiltonian
+for low-energy electronic states is derived from the two-orbital Hubbard model
+with a finite energy difference corresponding to the crystalline field
+splitting. The effective model is represented by the spin operators and the
+pseudo-spin operators for the spin-state degrees of freedom. The ground state
+phase diagram is analyzed by the mean-field approximation. In addition to the
+low-spin state and high-spin state phases, two kinds of the excitonic
+insulating phases emerge as a consequence of the competition between the
+crystalline field effect and the Hund coupling. The excitonic transition is
+classified to be an Ising-like transition reflecting a spontaneous breaking of
+the $Z_2$ symmetry. Magnetic structures in the two excitonic insulating phases
+are different from each other; an antiferromagnetic order and a spin nematic
+order. Collective excitations in each phase are examined by using the
+generalized spin-wave method. The Goldstone modes in the excitonic insulating
+phases appear in the dynamical correlation functions for the spins and
+pseudo-spin operators. Both the transverse and longitudinal spin excitation
+modes are active in the two excitonic insulating phases in contrast to the
+low-spin state and high-spin state phases. Connections of the present results
+to the perovskite cobalt oxides are discussed.",1602.07831v2
+2016-06-13,Observation of Spatial Charge and Spin Correlations in the 2D Fermi-Hubbard Model,"Strong electron correlations lie at the origin of transformative phenomena
+such as colossal magneto-resistance and high-temperature superconductivity.
+Already near room temperature, doped copper oxide materials display remarkable
+features such as a pseudo-gap and a ""strange metal"" phase with unusual
+transport properties. The essence of this physics is believed to be captured by
+the Fermi-Hubbard model of repulsively interacting, itinerant fermions on a
+lattice. Here we report on the site-resolved observation of charge and spin
+correlations in the two-dimensional (2D) Fermi-Hubbard model realized with
+ultracold atoms. Antiferromagnetic spin correlations are maximal at
+half-filling and weaken monotonically upon doping. Correlations between singly
+charged sites are negative at large doping, revealing the Pauli and correlation
+hole\textemdash a suppressed probability of finding two fermions near each
+other. However, as the doping is reduced below a critical value, correlations
+between such local magnetic moments become positive, signaling strong bunching
+of doublons and holes. Excellent agreement with numerical linked-cluster
+expansion (NLCE) and determinantal quantum Monte Carlo (DQMC) calculations is
+found. Positive non-local moment correlations directly imply potential energy
+fluctuations due to doublon-hole pairs, which should play an important role for
+transport in the Fermi-Hubbard model.",1606.04089v1
+2016-06-24,Spintronic nano-devices for bio-inspired computing,"Bio-inspired hardware holds the promise of low-energy, intelligent and highly
+adaptable computing systems. Applications span from automatic classification
+for big data management, through unmanned vehicle control, to control for
+bio-medical prosthesis. However, one of the major challenges of fabricating
+bio-inspired hardware is building ultra-high density networks out of complex
+processing units interlinked by tunable connections. Nanometer-scale devices
+exploiting spin electronics (or spintronics) can be a key technology in this
+context. In particular, magnetic tunnel junctions are well suited for this
+purpose because of their multiple tunable functionalities. One such
+functionality, non-volatile memory, can provide massive embedded memory in
+unconventional circuits, thus escaping the von-Neumann bottleneck arising when
+memory and processors are located separately. Other features of spintronic
+devices that could be beneficial for bio-inspired computing include tunable
+fast non-linear dynamics, controlled stochasticity, and the ability of single
+devices to change functions in different operating conditions. Large networks
+of interacting spintronic nano-devices can have their interactions tuned to
+induce complex dynamics such as synchronization, chaos, soliton diffusion,
+phase transitions, criticality, and convergence to multiple metastable states.
+A number of groups have recently proposed bio-inspired architectures that
+include one or several types of spintronic nanodevices. In this article we show
+how spintronics can be used for bio-inspired computing. We review the different
+approaches that have been proposed, the recent advances in this direction, and
+the challenges towards fully integrated spintronics-CMOS (Complementary metal -
+oxide - semiconductor) bio-inspired hardware.",1606.07700v2
+2016-07-18,Robust Upward Dispersion of the Neutron Spin Resonance in the Heavy Fermion Superconductor Ce$_{1-x}$Yb$_{x}$CoIn$_5$,"The neutron spin resonance is a collective magnetic excitation that appears
+in copper oxide, iron pnictide, and heavy fermion unconventional
+superconductors. Although the resonance is commonly associated with a
+spin-exciton due to the $d$($s^{\pm}$)-wave symmetry of the superconducting
+order parameter, it has also been proposed to be a magnon-like excitation
+appearing in the superconducting state. Here we use inelastic neutron
+scattering to demonstrate that the resonance in the heavy fermion
+superconductor Ce$_{1-x}$Yb$_{x}$CoIn$_5$ with $x=0,0.05,0.3$ has a ring-like
+upward dispersion that is robust against Yb-doping. By comparing our
+experimental data with random phase approximation calculation using the
+electronic structure and the momentum dependence of the $d_{x^2-y^2}$-wave
+superconducting gap determined from scanning tunneling microscopy for
+CeCoIn$_5$, we conclude the robust upward dispersing resonance mode in
+Ce$_{1-x}$Yb$_{x}$CoIn$_5$ is inconsistent with the downward dispersion
+predicted within the spin-exciton scenario.",1607.05326v1
+2016-07-20,Epitaxial growth of complex oxides on silicon by enhanced surface diffusion in large area pulsed laser deposition,"Homogeneous highly epitaxial LaSrMnO3 (LSMO) thin films have been grown on
+Yttria-stabilized-Zirconia (YsZ) / CeO2 buffer layers on technological relevant
+4"" silicon wafers using a Twente Solid State Technology B.V. (TSST) developed
+large area Pulsed Laser Deposition (PLD) setup. We study and show the results
+of the effect of an additional SrRuO3 buffer layer on the growth temperature
+dependent structural and magnetic properties of LSMO films. With the
+introduction of a thin SrRuO3 layer on top of the buffer stack, LSMO films show
+ferromagnetic behaviour for growth temperatures as low as 250C. We suggest that
+occurrence of epitaxial crystal growth of LSMO at these low growth temperatures
+can be understood by an improved surface diffusion, which ensures sufficient
+intermixing of surface species for formation of the correct phase. This
+intermixing is necessary because the full plume is collected on the 4"" wafer
+resulting in a compositional varying flux of species on the wafer, in contrast
+to small scale experiments.",1607.05955v1
+2016-09-05,Field-induced Conductance Switching by Charge-state Alternation in Organometallic Single-Molecule Junctions,"Charge transport through single molecules can be influenced by the charge and
+spin states of redox-active metal centres placed in the transport pathway.
+These molecular intrinsic properties are usually addressed by varying the
+molecules electrochemical and magnetic environment, a procedure that requires
+complex setups with multiple terminals. Here we show that oxidation and
+reduction of organometallic compounds containing either Fe, Ru or Mo centres
+can solely be triggered by the electric field applied to a two-terminal
+molecular junction. Whereas all compounds exhibit bias-dependent hysteresis,
+the Mo-containing compound additionally shows an abrupt voltage-induced
+conductance switching, yielding high to low current ratios exceeding 1000 at
+voltage stimuli of less than 1.0 V. DFT calculations identify a localized,
+redox active molecular orbital that is weakly coupled to the electrodes and
+closely aligned with the Fermi energy of the leads because of the
+spin-polarised ground state unique to the Mo centre. This situation opens an
+additional slow and incoherent hopping channel for transport, triggering a
+transient charging effect of the entire molecule and a strong hysteresis with
+unprecedented high low-to-high current ratios.",1609.01200v1
+2017-03-21,Anisotropic electrical resistance in mesoscopic LaAlO$_3$/SrTiO$_3$ devices with individual domain walls,"The crystal structure of bulk SrTiO$_3$(STO) transitions from cubic to
+tetragonal at around 105K. Recent local scanning probe measurements of
+LaAlO$_3$/SrTiO$_3$ (LAO/STO) interfaces indicated the existence of spatially
+inhomogeneous electrical current paths and electrostatic potential associated
+with the structural domain formation in the tetragonal phase of STO. However,
+how these effects impact the electron conduction in LAO/STO devices has not
+been fully studied. Here we report a study of temperature dependent electronic
+transport in combination with the polarized light microscopy of structural
+domains in mesoscopic scale LAO/STO devices. By reducing the spatial size of
+the conductive interface to be comparable to the size of a single tetragonal
+domain of STO, the anisotropy of interfacial electron conduction in
+relationship to the domain wall and its direction was characterized in the
+temperature range $T$=10-300K. It was found that the four-point resistance
+measured with current parallel to the domain wall in device is larger than the
+resistance measured perpendicular to the domain wall. This observation is
+qualitatively consistent with the current diverting effect from a more
+conductive domain wall within the sample. Among all the samples studied, the
+maximum resistance ratio found is at least 10 and could be as large as 10$^5$
+at $T$=10K. This electronic anisotropy may have implications on other oxide
+hetero-interfaces and the further understanding of electronic/magnetic
+phenomena found in LAO/STO.",1703.07229v1
+2017-03-25,Structure and physical properties of superconducting compounds Y(La)-Ba(Sr)-Cu-O,"The structure and physical properties of superconducting compounds
+Y(La)-Ba(Sr)-Cu-O are studied, the compounds being prepared by the method of
+cryogenic dispersion of a charge consisting of premix oxides and carbonates.
+Electrical conductivity and critical current density of the superconductors are
+measured over a wide temperature range of 10~$mK$ to 300~$K$. Degradation of
+the superconductor critical parameters in time and structural characteristics,
+magnetic susceptibility, heat capacity and acoustic properties are studied, and
+current-voltage characteristics are determined.",1703.08707v1
+2018-02-06,Via Method for Lithography Free Contact and Preservation of 2D Materials,"Atomically thin 2D materials span the common components of electronic
+circuits as metals, semi-conductors, and insulators, and can manifest
+correlated phases such as superconductivity, charge density waves, and
+magnetism. An ongoing challenge in the field is to incorporate these 2D
+materials into multi-layer hetero-structures with robust electrical contacts
+while preventing disorder and degradation. In particular, preserving and
+studying air-sensitive 2D materials has presented a significant challenge since
+they readily oxidize under atmospheric conditions. We report a new technique
+for contacting 2D materials, in which metal via contacts are integrated into
+flakes of insulating hexagonal boron nitride, and then placed onto the desired
+conducting 2D layer, avoiding direct lithographic patterning onto the 2D
+conductor. The metal contacts are planar with the bottom surface of the boron
+nitride and form robust contacts to multiple 2D materials. These structures
+protect air-sensitive 2D materials for months with no degradation in
+performance. This via contact technique will provide the capability to produce
+atomic printed circuit boards that can form the basis of more complex
+multi-layer heterostructures.",1802.02197v1
+2018-02-09,Superconducting properties of under- and over-doped Ba$_{x}$K$_{1-x}$BiO$_{3}$ perovskite oxide,"In the present study, we investigate the thermodynamic properties of the
+Ba$_{x}$K$_{1-x}$BiO$_{3}$ (BKBO) superconductor in the under- ($x=0.5$) and
+over-doped ($x=0.7$) regime, within the framework of the Migdal-Eliashberg
+formalism. The analysis is conducted to verify that the electron-phonon pairing
+mechanism is responsible for the induction of the superconducting phase in the
+mentioned compound. In particular, we show that BKBO is characterized by the
+relatively high critical value of the Coulomb pseudopotential, which changes
+with doping level and does not follow the Morel-Anderson model. In what
+follows, the corresponding superconducting band gap size and related
+dimensionless ratio are estimated to increase with the doping, in agreement
+with the experimental predictions. Moreover the effective mass of electrons is
+found to take on high values in the entire doping and temperature region.
+Finally, the characteristic dimensionless ratios for the superconducting band
+gap, the critical magnetic field and the specific heat for the superconducting
+state are predicted to exceed the limits set within the
+Bardeen-Cooper-Schrieffer theory, suggesting pivotal role of the
+strong-coupling and retardation effects in the analyzed compound. Presented
+results supplement our previous investigations and account for the
+strong-coupling phonon-mediated character of the superconducting phase in BKBO
+at any doping level.",1802.03434v3
+2018-04-09,Boiling crisis dynamics: low gravity experiments at high pressure,"To understand the boiling crisis mechanism, one can take advantage of the
+slowing down of boiling at high pressures, in the close vicinity of the
+liquid-vapor critical point of the given fluid. To preserve conventional bubble
+geometry, such experiments need to be carried out in low gravity. We report
+here two kinds of saturated boiling experiments. First we discuss the spatial
+experiments with SF$_6$ at 46$^\circ$ C. Next we address two ground-based
+experiments under magnetic gravity compensation with H$_2$ at 33 K. We compare
+both kinds of experiments and show their complementarity. The dry spots under
+vapor bubbles are visualized by using transparent heaters made with metal oxide
+films. We evidence two regimes of the dry spots growth: the regime of circular
+dry spots and the regime of chain coalescence of dry spots that immediately
+precedes the heater dryout. A recent H$_2$ experiment is shown to bridge the
+gap between the near-critical and low pressure boiling experiments.",1804.03050v1
+2018-04-09,Charged black strings and black branes in Lovelock theories,"It is well known that the Reissner-Norstrom solution of Einstein-Maxwell
+theory cannot be cylindrically extended to higher dimension, as with the black
+hole solutions in vacuum. In this paper we show that this result is
+circumvented in Lovelock gravity. We prove that the theory containing only the
+quadratic Lovelock term, the Gauss-Bonnet term, minimally coupled to a $U(1)$
+field, admits homogeneous black string and black brane solutions characterized
+by the mass, charge and volume of the flat directions. We also show that
+theories containing a single Lovelock term of order $n$ in the Lagrangian
+coupled to a $(p-1)$-form field admit simple oxidations only when $n$ equals
+$p$, giving rise to new, exact, charged black branes in higher curvature
+gravity. For General Relativity this stands for a Lagrangian containing the
+Einstein-Hilbert term coupled to a massless scalar field, and no-hair theorems
+in this case forbid the existence of black branes. In all these cases the field
+equations acquire an invariance under a global scaling scale transformation of
+the metric. As explicit examples we construct new magnetically charged black
+branes for cubic Lovelock theory coupled to a Kalb-Ramond field in dimensions
+$(3m+2)+q$, with $m$ and $q$ integers, and the latter denoting the number of
+extended flat directions. We also construct dyonic solutions in quartic
+Lovelock theory in dimension $(4m+2)+q$.",1804.03130v2
+2018-04-27,Interacting topological insulators: a review,"The discovery of the quantum spin Hall effect and topological insulators more
+than a decade ago has revolutionized modern condensed matter physics. Today,
+the field of topological states of matter is one of the most active and
+fruitful research areas for both experimentalists and theorists. The physics of
+topological insulators is typically well described by band theory and systems
+of non-interacting fermions. In contrast, several of the most fascinating
+effects in condensed matter physics merely exist due to electron-electron
+interactions, examples include unconventional superconductivity, the Kondo
+effect, and the Mott-Hubbard transition. The aim of this review article is to
+give an overview of the manifold directions which emerge when topological
+bandstructures and correlation physics interfere and compete. These include the
+study of the stability of topological bandstructures and correlated topological
+insulators. Interaction-induced topological phases such as the topological
+Kondo insulator provide another exciting topic. More exotic states of matter
+such as topological Mott insulator and fractional Chern insulators only exist
+due to the interplay of topology and strong interactions and do not have any
+bandstructure analogue. Eventually the relation between topological
+bandstructures and frustrated quantum magnetism in certain transition metal
+oxides is emphasized.",1804.10656v3
+2018-11-28,Computational Design of Flexible Electrides with Non-trivial Band Topology,"Electrides, with their excess electrons distributed in crystal cavities
+playing the role of anions, exhibit a variety of unique electronic and magnetic
+properties. In this work, we employ the first-principles crystal structure
+prediction to identify a new prototype of A$_3$B electride in which both
+interlayer spacings and intralayer vacancies provide channels to accommodate
+the excess electrons in the crystal. This A$_3$B type of structure is
+calculated to be thermodynamically stable for two alkaline metals oxides
+(Rb$_3$O and K$_3$O). Remarkably, the unique feature of multiple types of
+cavities makes the spatial arrangement of anionic electrons highly flexible via
+elastic strain engineering and chemical substitution, in contrast to the
+previously reported electrides characterized by a single topology of
+interstitial electrons. More importantly, our first-principles calculations
+reveal that Rb$_3$O is a topological Dirac nodal line semimetal, which is
+induced by the Rb-$s$ $\rightarrow$ O-$p$ band inversion at the general
+electronic k momentums in the Brillouin zone associated with the intersitial
+electric charges. The discovery of flexible electride in combining with
+topological electronic properties opens an avenue for electride design and
+shows great promises in electronic device applications.",1811.11334v2
+2019-05-08,Room Temperature Ferroelectric Ferromagnet in 1D Tetrahedral Chain Network,"Ferroelectricity occurs in crystals with broken spatial inversion symmetry.
+In conventional perovskite oxides, concerted ionic displacements within a
+three-dimensional network of transition metal-oxygen polyhedra (MOx) manifest
+spontaneous polarization. Meanwhile, some two-dimensional networks of MOx can
+foster geometric ferroelectricity with magnetism, owing to the distortion of
+the polyhedra. Because of the fundamentally different mechanism of
+ferroelectricity in a two-dimensional network, one can further challenge an
+uncharted mechanism of ferroelectricity in a one-dimensional channel of MOx and
+estimate its feasibility. This communication presents ferroelectricity and
+coupled ferromagnetism in a one-dimensional FeO4 tetrahedral chain network of a
+brownmillerite SrFeO2.5 epitaxial thin film. The result provides a new paradigm
+for designing low-dimensional MOx networks, which is expected to benefit the
+realization of macroscopic ferro-ordering materials including ferroelectric
+ferromagnets.",1905.02931v1
+2020-07-11,Magnon-bipolar carrier drag thermopower in antiferromagnetic/ferromagnetic semiconductors: theoretical formulation and experimental evidence,"Quantized spin-wave known as magnon, a bosonic quasiparticle, can drag
+electrons or holes via sd exchange interaction and boost the thermopower over
+the conventional diffusive thermopower. P-type magnon-drag thermopower has been
+observed in both ferromagnetic and antiferromagnetic metallic and degenerate
+semiconductors. However, it has been less reported for intrinsic or n-type
+magnetic semiconductors; therefore, the impact of magnon-bipolar carrier drag
+on thermopower has remained unexplored. Here, a theoretical model for
+magnon-bipolar carrier drag thermopower is derived based on the magnon-carrier
+interaction lifetimes. The model predicts that the bipolar carrier drag
+thermopower becomes independent of both the carrier and magnon relaxation
+times. A proof of concept experiment is presented that confirms this
+prediction. We also report the observation of magnon-carrier drag thermopower
+in n-type and intrinsic ferromagnetic semiconductors experimentally. The p-type
+antiferromagnetic MnTe is doped with different amounts of Cr to produce
+non-degenerate and n-type semiconductors of various carrier concentrations. Cr
+dopants have a donor nature and create ferromagnetic-antiferromagnetic clusters
+due to the Cr3+ oxidation state. Heat capacity measurements confirm the
+presence of magnons in Cr-doped MnTe. It is shown that the magnon-drag
+thermopower is significantly reduced for 3%-5% Cr-doped samples due to bipolar
+drag effects and becomes negative for 14% and 20% Cr-doped MnTe due to dominant
+magnon-electron drag thermopower.",2007.05682v1
+2020-07-13,Molecule Oxygen Induced Ferromagnetism and Half-metallicity in α-BaNaO4: A First Principles Study,"Molecule oxygen resembles 3d and 4f metals in exhibiting long-range spin
+ordering and electron strong correlated behaviors in compounds. The
+ferromagnetic spin ordering and half-metallicity, however, are quite elusive
+and have not been well acknowl-edged. In this article, we address this issue to
+study how spins will interact each other if the oxygen dimers are arranged in a
+dif-ferent way from that in the known super- and per-oxides by first principles
+calculations. Based on the results of structure search, thermodynamic study and
+lattice dynamics, we show that tetragonal {\alpha}-BaNaO4 is a stable
+half-metal with a Curie temperature at 120 K, a first example in this class of
+compounds. Like 3d and 4f metals, the O2 dimer carries a local magnetic moment
+0.5 {\mu}B due to the unpaired electrons in its {\pi}* orbitals. This compound
+can be regarded as forming from the O2 dimer layers stacking in a head to head
+way. Different from that in AO2 (A=K, Rb, Cs), the spins are both
+ferromagnetically coupled within and between the layers. Spin polarization
+occurs in {\pi}* orbitals with spin-up electrons fully occupying the valence
+band and spin-down electrons partially the conduction band, forming the
+semiconducting and metallic channels, respectively. Our results highlight the
+im-portance of geometric arrangement of O2 dimers in inducing ferromagnetism
+and other novel properties in O2 dimer containing compounds.",2007.06433v1
+2020-07-15,Effects of paramagnetic fluctuations on the thermochemistry of MnO (100) surfaces in the oxygen evolution reaction,"We investigated the effects of paramagnetic (PM) fluctuations on the
+thermochemistry of the MnO(100) surface in the oxygen evolution reaction (OER)
+using the ""noncollinear magnetic sampling method \textit{plus} $U$""
+(NCMSM$+U$). Various physical properties, such as the electronic structure,
+free energy, and charge occupation, of the MnO (100) surface in the PM state
+with several OER intermediates, were reckoned and compared to those in the
+antiferromagnetic (AFM) state. We found that PM fluctuation enhances charge
+transfer from a surface Mn ion to each of the intermediates and strengthens the
+chemical bond between them, while not altering the overall features, such as
+the rate determining step and resting state, in reaction pathways. The enhanced
+charge transfer can be attributed to the delocalized nature of valence bands
+observed in the PM surface. In addition, it was observed that chemical-bond
+enhancement depends on the intermediates, resulting in significant deviations
+in reaction energy barriers. Our study suggests that PM fluctuations play a
+significant role in the thermochemistry of chemical reactions occurring on
+correlated oxide surfaces.",2007.07790v2
+2020-07-20,Revealing the site selective local electronic structure of Co$_{3}$O$_{4}$ using $2p3d$ resonant inelastic X-ray scattering,"We investigate mixed-valence oxide Co$_3$O$_4$ using Co $2p3d$ resonant
+inelastic X-ray scattering (RIXS). By setting resonant edges at Co$^{2+}$ and
+Co$^{3+}$ ions, the $dd$ excitations on the two Co sites are probed
+selectively, providing detailed information on the local electronic structure
+of Co$_3$O$_4$. The $2p3d$ RIXS result reveals the $^4$T$_{2}$ excited state of
+tetrahedral Co$^{2+}$ site at 0.5 eV beyond the discriminative power of optical
+absorption spectroscopies. Additionally, the $^3$T$_{2g}$ excited stated at 1.3
+eV is uniquely identified for the octahedral Co$^{3+}$ site. Guided by cluster
+multiplet simulations, the ground-state character of the Co$^{2+}$ and
+Co$^{3+}$ site is determined to be high-spin $^4$A$_{2}$(T$_d$) and low-spin
+$^1$A$_{1g}$(O$_h$), respectively. This indicates that only the Co$^{2+}$ site
+is magnetically active site at low-temperatures in Co$_3$O$_4$. The
+ligand-to-metal charge transfer analysis suggests a formation of a strong
+covalent bonding between Co and O ions at the Co$^{3+}$ site, while Co$^{2+}$
+is rather ionic.",2007.10280v1
+2010-05-14,"Electron Confinement, Orbital Ordering, and Orbital Moments in $d^0$-$d^1$ Oxide Heterostructures","The (SrTiO$_3$)$_m$/(SrVO$_3$)$_n$ $d^0-d^1$ multilayer system is studied
+with first principles methods through the observed insulator-to-metal
+transition with increasing thickness of the SrVO$_3$ layer. When correlation
+effects with reasonable magnitude are included, crystal field splittings from
+the structural relaxations together with spin-orbit coupling (SOC) determines
+the behavior of the electronic and magnetic structures. These confined slabs of
+SrVO$_3$ prefer $Q_{orb}$=($\pi,\pi$) orbital ordering of $\ell_z = 0$ and
+$\ell_z = -1$ ($j_z=-1/2$) orbitals within the plane, accompanied by
+$Q_{spin}$=(0,0) spin order (ferromagnetic alignment). The result is a
+SOC-driven ferromagnetic Mott insulator. The orbital moment of 0.75 $\mu_B$
+strongly compensates the spin moment on the $\ell_z = -1$ sublattice. The
+insulator-metal transition for $n = 1 \to 5$ (occurring between $n$=4 and
+$n$=5) is reproduced. Unlike in the isoelectronic $d^0-d^1$ TiO$_2$/VO$_2$
+(rutile structure) system and in spite of some similarities in orbital
+ordering, no semi-Dirac point [{\it Phys. Rev. Lett.} {\bf 102}, 166803 (2009)]
+is encountered, but the insulator-to-metal transition occurs through a
+different type of unusual phase. For n=5 this system is very near (or at) a
+unique semimetallic state in which the Fermi energy is topologically determined
+and the Fermi surface consists of identical electron and hole Fermi circles
+centered at $k$=0. The dispersion consists of what can be regarded as a
+continuum of radially-directed Dirac points, forming a ""Dirac circle"".",1005.2484v1
+2013-08-01,Electronic superlattice revealed by resonant scattering from random impurities in Sr3Ru2O7,"Resonant elastic x-ray scattering (REXS) is an exquisite element-sensitive
+tool for the study of subtle charge, orbital, and spin superlattice orders
+driven by the valence electrons, which therefore escape detection in
+conventional x-ray diffraction (XRD). Although the power of REXS has been
+demonstrated by numerous studies of complex oxides performed in the soft x-ray
+regime, the cross section and photon wavelength of the material-specific
+elemental absorption edges ultimately set the limit to the smallest
+superlattice amplitude and periodicity one can probe. Here we show -- with
+simulations and REXS on Mn-substituted Sr$_3$Ru$_2$O$_7$ -- that these
+limitations can be overcome by performing resonant scattering experiments at
+the absorption edge of a suitably-chosen, dilute impurity. This establishes
+that -- in analogy with impurity-based methods used in electron-spin-resonance,
+nuclear-magnetic resonance, and M\""ossbauer spectroscopy -- randomly
+distributed impurities can serve as a non-invasive, but now momentum-dependent
+probe, greatly extending the applicability of resonant x-ray scattering
+techniques.",1308.0185v1
+2013-08-01,Topological Flat Band Models and Fractional Chern Insulators,"Topological insulators and their intriguing edge states can be understood in
+a single-particle picture and can as such be exhaustively classified.
+Interactions significantly complicate this picture and can lead to entirely new
+insulating phases, with an altogether much richer and less explored
+phenomenology. Most saliently, lattice generalizations of fractional quantum
+Hall states, dubbed fractional Chern insulators, have recently been predicted
+to be stabilized by interactions within nearly dispersionless bands with
+non-zero Chern number, $C$. Contrary to their continuum analogues, these states
+do not require an external magnetic field and may potentially persist even at
+room temperature, which make these systems very attractive for possible
+applications such as topological quantum computation. This review recapitulates
+the basics of tight-binding models hosting nearly flat bands with non-trivial
+topology, $C\neq 0$, and summarizes the present understanding of interactions
+and strongly correlated phases within these bands. Emphasis is made on
+microscopic models, highlighting the analogy with continuum Landau level
+physics, as well as qualitatively new, lattice specific, aspects including
+Berry curvature fluctuations, competing instabilities as well as novel
+collective states of matter emerging in bands with $|C|>1$. Possible
+experimental realizations, including oxide interfaces and cold atom
+implementations as well as generalizations to flat bands characterized by other
+topological invariants are also discussed.",1308.0343v2
+2014-03-06,Spin-orbital Entangled Molecular $j_{\rm eff}$ States in Lacunar Spinel Compounds,"The entanglement of the spin and orbital degrees of freedom through the
+spin-orbit coupling has been actively studied in condensed matter physics. In
+several iridium-oxide systems, the spin-orbital entangled state, identified by
+the effective angular momentum $j_{\rm eff}$, can host novel quantum phases
+with the help of electron correlations. Here, we show that a series of lacunar
+spinel compounds, Ga$M_4X_8$ ($M$ = Nb, Mo, Ta, and W and $X$ = S, Se, and Te),
+gives rise to a $\textit{molecular}$ $j_{\rm eff}$ state as a new spin-orbital
+composite on which the low energy effective Hamiltonian is based. A wide range
+of electron correlations is accessible by tuning the bandwidth under external
+and/or chemical pressure, enabling us to investigate the interesting
+cooperation between spin-orbit coupling and electron correlations. As
+illustrative examples, a two-dimensional topological insulating phase and an
+anisotropic spin Hamiltonian are investigated in the weak and strong coupling
+regimes, respectively. Our finding can provide an ideal platform for exploring
+$j_{\rm eff}$ physics and the resulting emergent phenomena.",1403.1358v2
+2014-03-06,Channelling study of La$_{1-x}$Sr$_x$CoO$_3$ films on different substrates,"The cobalt oxide system LaCoO$_3$ and its Sr-doped child compounds have been
+intensively studied for decades due to their intriguing magnetic and electronic
+properties. Preparing thin La$_{1-x}$Sr$_x$CoO$_3$ (LSCO) films on different
+substrates allows for studies with a new type of perturbation, as the films are
+subject to substrate-dependent epitaxial strain. By choosing a proper substrate
+for a thin film grow, not only compressing but also tensile strain can be
+applied. The consequences for the fundamental physical properties are dramatic:
+while compressed films are metallic, as the bulk material, films under tensile
+strain become insulating. The goal of this work is to determine the strain
+tensor in LSCO films prepared on LaAlO$_3$ and SrTiO$_3$ substrates by pulsed
+laser deposition using RBS/channelling methods. Apart from the composition and
+defect structure of the samples, the depth dependence of the strain tensor, the
+cell parameters, and the volume of the unit cell are also determined.
+Asymmetric behaviour of the strained cell parameters is found on both
+substrates. This asymmetry is rather weak in the case of LSCO film grown on
+LaAlO$_3$, while stronger on SrTiO$_3$ substrate. The strain is more effective
+at the interface, some relaxation can be observed near to the surface.",1403.1439v1
+2016-11-08,Experimental simulation of next-nearest-neighbor Heisenberg chain with photonic crystal waveguide array,"Next-nearest-neighbor Heisenberg chain plays important roles in solid state
+physics, such as predicting exotic electric properties of two-dimensional
+materials or magnetic properties of organic compounds. Direct experimental
+studies of the many-body electron systems or spin systems associating to these
+materials are challenging tasks, while optical simulation provides an effective
+and economical way for immediate observation. Comparing with bulk optics,
+integrated optics are more of fascinating for steady, large scale and long-time
+evolution simulations. Photonic crystal is an artificial microstructure
+material with multiple methods to tune the propagation properties, which are
+essential for various simulation tasks. Here we report for the first time an
+experimental simulation of next-nearest-neighbor Heisenberg chain with an
+integrated optical chip of photonic crystal waveguide array. The use of
+photonic crystal enhances evanescent field thus allows coupling between
+next-nearest-neighbor waveguides in such a planar waveguide array, without
+breaking the weak coupling condition of the coupled mode equation.
+Particularly, similarities between the model and coherent light propagation
+could reach 0.99 in numerical simulations and 0.89 in experiment. Localization
+effect induced by second-order coupling and coupling strengthening with
+increasing wavelengths were also revealed in both numerical simulations and
+experiments. The platform proposed here is compatible with mature complementary
+metal oxide semiconductor technology thus possesses the potential for
+larger-scale problems and photonic crystals further allows simulations of
+specific target Hamiltonians.",1611.02520v1
+2017-01-09,Cooperative elastic fluctuations provide tuning of the metal-insulator transition,"Metal to insulator transitions (MITs) driven by strong electronic
+correlations are common in condensed matter systems, and are associated with
+some of the most remarkable collective phenomena in solids, including
+superconductivity and magnetism. Tuning and control of the transition holds the
+promise of novel, low power, ultrafast electronics, but the relative roles of
+doping, chemistry, elastic strain and other applied fields has made systematic
+understanding difficult to obtain. Here we point out that existing data on
+tuning of the MIT in perovskite transition metal oxides through ionic size
+effects provides evidence of systematic and large effects on the phase
+transition due to dynamical fluctuations of the elastic strain, which have been
+usually neglected. This is illustrated by a simple yet quantitative statistical
+mechanical calculation in a model that incorporates cooperative lattice
+distortions coupled to the electronic degrees of freedom. We reproduce the
+observed dependence of the transition temperature on cation radius in the
+well-studied manganite and nickelate materials. Since the elastic couplings are
+generically quite strong, these conclusions will broadly generalize to all MITs
+that couple to a change in lattice symmetry.",1701.02318v3
+2017-04-11,Competition between electron pairing and phase coherence in superconducting interfaces,"The large diversity of exotic electronic phases displayed by two-dimensional
+superconductors confronts physicists with new challenges. These include the
+recently discovered quantum Griffith singularity in atomic Ga films,
+topological phases in proximized topological insulators and unconventional
+Ising pairing in transition metal dichalcogenide layers. In LaAlO3/SrTiO3
+heterostructures, a gate tunable superconducting electron gas is confined in a
+quantum well at the interface between two insulating oxides. Remarkably, the
+gas coexists with both magnetism and strong Rashba spin-orbit coupling and is a
+candidate system for the creation of Majorana fermions. However, both the
+origin of superconductivity and the nature of the transition to the normal
+state over the whole doping range remain elusive. Missing such crucial
+information impedes harnessing this outstanding system for future
+superconducting electronics and topological quantum computing. Here we show
+that the superconducting phase diagram of LaAlO3/SrTiO3 is controlled by the
+competition between electron pairing and phase coherence. Through resonant
+microwave experiments, we measure the superfluid stiffness and infer the gap
+energy as a function of carrier density. Whereas a good agreement with the
+Bardeen-Cooper-Schrieffer (BCS) theory is observed at high carrier doping, we
+find that the suppression of Tc at low doping is controlled by the loss of
+macroscopic phase coherence instead of electron pairing as in standard BCS
+theory. We find that only a very small fraction of the electrons condenses into
+the superconducting state and propose that this corresponds to the weak filling
+of a high-energy dxz/yz band, more apt to host superconductivity",1704.03365v1
+2017-04-19,Potential Fluctuations at Low Temperatures in Mesoscopic-Scale SmTiO$_{3}$/SrTiO$_{3}$/SmTiO$_{3}$ Quantum Well Structures,"Heterointerfaces of SrTiO$_{3}$ with other transition metal oxides make up an
+intriguing family of systems with a bounty of coexisting and competing physical
+orders. Some examples, such as LaAlO$_{3}$/SrTiO$_{3}$, support a high carrier
+density electron gas at the interface whose electronic properties are
+determined by a combination of lattice distortions, spin-orbit coupling,
+defects, and various regimes of magnetic and charge ordering. Here, we study
+electronic transport in mesoscale devices made with heterostructures of
+SrTiO$_{3}$ sandwiched between layers of SmTiO$_{3}$, in which the transport
+properties can be tuned from a regime of Fermi-liquid like resistivity ($\rho
+\sim T^{2}$) to a non-Fermi liquid ($\rho \sim T^{5/3}$) by controlling the
+SrTiO$_{3}$ thickness. In mesoscale devices at low temperatures, we find
+unexpected voltage fluctuations that grow in magnitude as $T$ is decreased
+below 20 K, are suppressed with increasing contact electrode size, and are
+independent of the drive current and contact spacing distance.
+Magnetoresistance fluctuations are also observed, which are reminiscent of
+universal conductance fluctuations but not entirely consistent with their
+conventional properties. Candidate explanations are considered, and a mechanism
+is suggested based on mesoscopic temporal fluctuations of the Seebeck
+coefficient. An improved understanding of charge transport in these model
+systems, especially their quantum coherent properties, may lead to insights
+into the nature of transport in strongly correlated materials that deviate from
+Fermi liquid theory.",1704.05744v1
+2018-05-24,"Evolution of electronic and crystal structure during room-temperature annealing of quenched REBa2Cu3O6+d, RE=Y, Nd","The crystal structure parameters and the low-temperature magnetic moment of
+the HTSC cuprates YBa2Cu3O6+d, Y1-xCaxBa2Cu3O6+d, and Nd1+xBa2-xCu3O6+d, x =
+0.2 are recorded after quenching them from the temperature of oxidative
+annealing. The subject of the present study is the aging effect, which results
+in an increase in the critical temperature Tc and a decrease in the c parameter
+of the crystal lattice for a while after the quenching. On the example of
+YBa2Cu3O6+d, it is shown that the oxygen content dependence of c undergoes the
+following changes with time: (1) there is an increase in the dependence slope
+with respect to the (6+d)-axis; (2) there is an increase in the dependence
+nonlinearity. The first type of changes is explained by an increase in the
+valence of copper ions in the CuOd planes that is accompanied by a decrease in
+their radius. The second type is explained by the electrostatic interaction of
+the CuO2 structural planes due to the accumulation on them electron holes.
+Calculation of the parameter c changes shows good quantitative agreement with
+the experimental data. The data obtained for the compounds Y1-xCaxBa2Cu3O6+d,
+and Nd1+xBa2-xCu3O6+d (the cases of the hole and electron doping of
+CuO2-planes) are discussed on the basis of the model representation developed
+by us for YBa2Cu3O6+d.",1805.09788v1
+2008-07-13,Electronic structure of the iron-based superconductor LaOFeP,"The recent discovery of superconductivity in the so-called iron-oxypnictide
+family of compounds has generated intense interest. The layered crystal
+structure with transition metal ions in planar square lattice form and the
+discovery of spin-density-wave order near 130 K seem to hint at a strong
+similarity with the copper oxide superconductors. A burning current issue is
+the nature of the ground state of the parent compounds. Two distinct classes of
+theories have been put forward depending on the underlying band structures:
+local moment antiferromagnetic ground state for strong coupling approach and
+itinerant ground state for weak coupling approach. The local moment magnetism
+approach stresses on-site correlations and proximity to a Mott insulating state
+and thus the resemblance to cuprates; while the latter approach emphasizes the
+itinerant electron physics and the interplay between the competing
+ferromagnetic and antiferromagnetic fluctuations. Such a controversy is partly
+due to the lack of conclusive experimental information on the electronic
+structures. Here we report the first angle-resolved photoemission spectroscopy
+(ARPES) investigation of LaOFeP (Tc = 5.9 K), the first reported iron-based
+superconductor. Our results favor the itinerant ground state, albeit with band
+renormalization. In addition, our data reveal important differences between
+these and copper based superconductors.",0807.2009v1
+2011-11-11,Surface-enhanced charge-density-wave instability in underdoped Bi2201,"Neutron and x-ray scattering experiments have provided mounting evidence for
+spin and charge ordering phenomena in underdoped cuprates. These range from
+early work on stripe correlations in Nd-LSCO to the latest discovery of
+charge-density-waves in YBCO. Both phenomena are characterized by a pronounced
+dependence on doping, temperature, and an externally applied magnetic field.
+Here we show that these electron-lattice instabilities exhibit also a
+previously unrecognized bulk-surface dichotomy. Surface-sensitive electronic
+and structural probes uncover a temperature-dependent evolution of the CuO2
+plane band dispersion and apparent Fermi pockets in underdoped Bi2201, which is
+directly associated with an hitherto-undetected strong temperature dependence
+of the incommensurate superstructure periodicity below 130K. In stark contrast,
+the structural modulation revealed by bulk-sensitive probes is temperature
+independent. These findings point to a surface-enhanced incipient
+charge-density-wave instability, driven by Fermi surface nesting. This
+discovery is of critical importance in the interpretation of single-particle
+spectroscopy data and establishes the surface of cuprates and other complex
+oxides as a rich playground for the study of electronically soft phases.",1111.2673v3
+2012-01-27,Interface induced high temperature superconductivity in single unit-cell FeSe films on SrTiO3,"Searching for superconducting materials with high transition temperature (TC)
+is one of the most exciting and challenging fields in physics and materials
+science. Although superconductivity has been discovered for more than 100
+years, the copper oxides are so far the only materials with TC above 77 K, the
+liquid nitrogen boiling point. Here we report an interface engineering method
+for dramatically raising the TC of superconducting films. We find that one
+unit-cell (UC) thick films of FeSe grown on SrTiO3 (STO) substrates by
+molecular beam epitaxy (MBE) show signatures of superconducting transition
+above 50 K by transport measurement. A superconducting gap as large as 20 meV
+of the 1 UC films observed by scanning tunneling microcopy (STM) suggests that
+the superconductivity could occur above 77 K. The occurrence of
+superconductivity is further supported by the presence of superconducting
+vortices under magnetic field. Our work not only demonstrates a powerful way
+for finding new superconductors and for raising TC, but also provides a
+well-defined platform for systematic study of the mechanism of unconventional
+superconductivity by using different superconducting materials and substrates.",1201.5694v1
+2014-05-07,"Density, porosity, mineralogy, and internal structure of cosmic dust and alteration of its properties during high velocity atmospheric entry","X-ray microtomography (XMT), X-ray diffraction (XRD) and magnetic hysteresis
+measurements were used to determine micrometeorite internal structure,
+mineralogy, crystallography, and physical properties at ~{\mu}m resolution. The
+study samples include unmelted, partially melted (scoriaceous) and completely
+melted (cosmic spherules) micrometeorites. This variety not only allows
+comparison of the mineralogy and porosity of these three micrometeorite types,
+but also reveals changes in meteoroid properties during atmospheric entry at
+various velocities. At low entry velocities, meteoroids do not melt, and their
+physical properties do not change. The porosity of unmelted micrometeorites
+varies considerably (0-12%) with one friable example having porosity around
+50%. At higher velocities, the range of meteoroid porosity narrows, but average
+porosity increases (to 16-27%) due to volatile evaporation and partial melting
+(scoriaceous phase). Metal distribution seems to be mostly unaffected at this
+stage. At even higher entry velocities, complete melting follows the
+scoriaceous phase. Complete melting is accompanied by metal oxidation and
+redistribution, loss of porosity (1 $\pm$ 1%), and narrowing of the bulk (3.2
+$\pm$ 0.5 g/cm$^{3}$) and grain (3.3 $\pm$ 0.5 g/cm$^{3}$) density range.
+Melted cosmic spherules with a barred olivine structure show an oriented
+crystallographic structure, whereas other subtypes do not.",1405.1596v2
+2015-12-05,Coherent coupling between a quantum dot and a donor in silicon,"Individual donors in silicon chips are used as quantum bits with extremely
+low error rates. However, physical realizations have been limited to one donor
+because their atomic size causes fabrication challenges. Quantum dot qubits, in
+contrast, are highly adjustable using electrical gate voltages. This
+adjustability could be leveraged to deterministically couple donors to quantum
+dots in arrays of qubits. In this work, we demonstrate the coherent interaction
+of a $^{31}$P donor electron with the electron of a metal-oxide-semiconductor
+quantum dot. We form a logical qubit encoded in the spin singlet and triplet
+states of the two-electron system. We show that the donor nuclear spin drives
+coherent rotations between the electronic qubit states through the contact
+hyperfine interaction. This provides every key element for compact two-electron
+spin qubits requiring only a single dot and no additional magnetic field
+gradients, as well as a means to interact with the nuclear spin qubit.",1512.01606v3
+2015-12-07,Computational and experimental investigation of unreported transition metal selenides and sulphides,"Expanding the library of known inorganic materials with functional electronic
+or magnetic behavior is a longstanding goal in condensed matter physics and
+materials science. Recently, the transition metal chalchogenides including
+selenium and sulfur have been of interest because of their correlated-electron
+properties, as seen in the iron based superconductors and the transition metal
+dichalcogenides. However, the chalcogenide chemical space is less explored than
+that of oxides, and there is an open question of whether there may be new
+materials heretofore undiscovered. We perform a systematic combined theoretical
+and experimental search over ternary phase diagrams that are empty in the
+Inorganic Crystal Structure Database containing cations, transition metals, and
+one of selenium or sulfur. In these 27 ternary systems, we use a probabilistic
+model to reduce the likelihood of false negative predictions, which results in
+a list of 24 candidate materials. We then conduct a variety of synthesis
+experiments to check the candidate materials for stability. While the
+prediction method did obtain previously unknown compositions that are predicted
+stable within density functional theory, none of the candidate materials formed
+in our experiments. We come to the conclusion that these phase diagrams are
+""empty"" in the case of bulk synthesis, but it remains a possibility that
+alternate synthesis routes may produce some of these phases.",1512.02214v3
+2015-12-27,Two types of superconducting domes in unconventional superconductors,"Uncovering the origin of unconventional superconductivity is often plagued by
+the overwhelming material diversity with varying normal and superconducting
+(SC) properties. In this article, we deliver a comprehensive study of the SC
+properties and phase diagrams using multiple tunings (such as disorder,
+pressure or magnetic field in addition to doping and vice versa) across several
+families of unconventional superconductors, including the copper-oxides,
+heavy-fermions, organics and the recently discovered iron-pnictides,
+iron-chalcogenides, and oxybismuthides. We discover that all these families
+often possess two types of SC domes, with lower and higher superconducting
+transition temperatures Tc, both unconventional but with distinct SC and normal
+states properties. The lower Tc dome arises with or without a quantum critical
+point (QCP), and not always associated with a non-Fermi liquid (NFL)
+background. On the contrary, the higher-Tc dome clearly stems from a NFL or
+strange metal phase, without an apparent intervening phase transition or a QCP.
+The two domes appear either fully separated in the phase diagram, or merged
+into one, or arise independently owing to their respective normal state
+characteristics. Our findings suggest that a QCP-related mechanism is an
+unlikely scenario for the NFL phase in these materials, and thereby narrows the
+possibility towards short-range fluctuations of various degrees of freedom in
+the momentum and frequency space. We also find that NFL physics may be a
+generic route to higher-Tc superconductivity.",1512.08186v2
+2016-05-03,On the Structural Origin of the Single-ion Magnetic Anisotropy in LuFeO3,"Electronic structures for the conduction bands of both hexagonal and
+orthorhombic LuFeO3 thin films have been measured using x-ray absorption
+spectroscopy at oxygen K (O K) edge. Dramatic differences in both the spectra
+shape and the linear dichroism are observed. These differences in the spectra
+can be explained using the differences in crystal field splitting of the metal
+(Fe and Lu) electronic states and the differences in O 2p-Fe 3d and O 2p-Lu 5d
+hybridizations. While the oxidation states has not changed, the spectra are
+sensitive to the changes in the local environments of the Fe3+ and Lu3+ sites
+in the hexagonal and orthorhombic structures. Using the crystal-field splitting
+and the hybridizations that are extracted from the measured electronic
+structures and the structural distortion information, we derived the
+occupancies of the spin minority states in Fe3+, which are non-zero and uneven.
+The single ion anisotropy on Fe3+ sites is found to originate from these uneven
+occupancies of the spin minority states via spin-orbit coupling in LuFeO3.",1605.01111v1
+2016-05-23,Electron doping evolution of the neutron spin resonance in NaFe$_{1-x}$Co$_{x}$As,"Neutron spin resonance, a collective magnetic excitation coupled to
+superconductivity, is one of the most prominent features shared by a broad
+family of unconventional superconductors including copper oxides, iron
+pnictides, and heavy fermions. In this work, we study the doping evolution of
+the resonances in NaFe$_{1-x}$Co$_x$As covering the entire superconducting
+dome. For the underdoped compositions, two resonance modes coexist. As doping
+increases, the low-energy resonance gradually loses its spectral weight to the
+high-energy one but remains at the same energy. By contrast, in the overdoped
+regime we only find one single resonance, which acquires a broader width in
+both energy and momentum, but retains approximately the same peak position even
+when $T_c$ drops by nearly a half compared to optimal doping. These results
+suggest that the energy of the resonance in electron overdoped
+NaFe$_{1-x}$Co$_x$As is neither simply proportional to $T_c$ nor the
+superconducting gap, but is controlled by the multi-orbital character of the
+system and doped impurity scattering effect.",1605.06890v1
+2017-06-01,Leakage-free electrolytes with different conductivity for non-volatile memory device utilizing insulator/metal ferromagnet transition of SrCoOx,"The electrochemical switching of SrCoOx-based non-volatile memory with
+thin-film-transistor structure was examined by using liquid-leakage-free
+electrolytes with different conductivity (s) as the gate insulator. We first
+examined leakage-free water, which is incorporated in the amorphous (a-) 12CaO
+7Al2O3 film with nanoporous structure (CAN), but the electrochemical
+oxidation/reduction of SrCoOx layer required the application of high gate
+voltage (Vg) up to 20 V for a very long retention-time (t) 40 minutes,
+primarily due to the low s (2.0 x 10-8 S cm-1 at RT) of leakage-free water.We
+then controlled the s of leakage-free electrolyte, infiltrated in the a-NaxTaO3
+film with nanopillar array structure, from 8.0 x 10-8 S cm-1 to 2.5 x 10-6 S
+cm-1 at RT by changing the x = 0.01-1.0. As the result, the t, required for the
+metallization of SrCoOx layer under small Vg = -3 V, becomes two orders of
+magnitude shorter with increase of the s of the a-NaxTaO3 leakage-free
+electrolyte. These results indicate that the ion migration in the leakage-free
+electrolyte is the rate-determining step for the electrochemical switching,
+compared to the other electrochemical process, and the high s of the
+leakage-free electrolyte is the key factor for the development of the
+non-volatile SrCoOx-based electro-magnetic phase switching device.",1706.00132v1
+2017-10-18,Using MRI Cell Tracking to Monitor Immune Cell Recruitment in Response to a Peptide-Based Cancer Vaccine,"Purpose: MRI cell tracking can be used to monitor immune cells involved in
+the immunotherapy response, providing insight into the mechanism of action,
+temporal progression of tumour growth and individual potency of therapies. To
+evaluate whether MRI could be used to track immune cell populations in response
+to immunotherapy, CD8+ cytotoxic T cells (CTLs), CD4+CD25+FoxP3+ regulatory T
+cells (Tregs) and myeloid derived suppressor cells (MDSCs) were labelled with
+superparamagnetic iron oxide (SPIO) particles.
+  Methods: SPIO-labelled cells were injected into mice (one cell type/mouse)
+implanted with an HPV-based cervical cancer model. Half of these mice were also
+vaccinated with DepoVaxTM, a lipid-based vaccine platform that was developed to
+enhance the potency of peptide-based vaccines.
+  Results: MRI visualization of CTLs, Tregs and MDSCs was apparent 24 hours
+post-injection, with hypointensities due to iron labelled cells clearing
+approximately 72 hours post-injection. Vaccination resulted in increased
+recruitment of CTLs and decreased recruitment of MDSCs and Tregs to the tumour.
+We also found that MDSC and Treg recruitment was positively correlated with
+final tumour volume.
+  Conclusion: This type of analysis can be used to non-invasively study changes
+in immune cell recruitment in individual mice over time, potentially allowing
+improved application and combination of immunotherapies.",1710.06817v1
+2018-01-14,Spin filling and orbital structure of the first six holes in a silicon metal-oxide-semiconductor quantum dot,"The spin states of electrons confined in semiconductor quantum dots form a
+promising platform for quantum computation. Recent studies of silicon CMOS
+qubits have shown coherent manipulation of electron spin states with extremely
+high fidelity. However, manipulation of single electron spins requires large
+oscillatory magnetic fields to be generated on-chip, making it difficult to
+address individual qubits when scaling up to multi-qubit devices. The
+spin-orbit interaction allows spin states to be controlled with electric
+fields, which act locally and are easier to generate. While the spin-orbit
+interaction is weak for electrons in silicon, valence band holes have an
+inherently strong spin-orbit interaction. However, creating silicon quantum
+dots in which a single hole can be localised, in an architecture that is
+suitable for scale-up to a large number of qubits, is a challenge. Here we
+report a silicon quantum dot, with an integrated charge sensor, that can be
+operated down to the last hole. We map the spin states and orbital structure of
+the first six holes, and show they follow the Fock-Darwin spectrum. We also
+find that hole-hole interactions are extremely strong, reducing the two-hole
+singlet-triplet splitting by 90% compared to the single particle level spacing
+of 3.5 meV. These results provide a route to single hole spin quantum bits in a
+planar silicon CMOS architecture.",1801.04494v1
+2018-01-15,The cellular uptake mechanism of SPIONs: an in-vitro study,"The Superparamagnetic Iron Oxide Nanoparticles (SPIONs) of sizes ranging from
+10-50 nm are being used in a large number of biological studies because of
+their peculiar characteristics of inducing local hyperthermia, MR imaging,
+specific targeting and drug delivery. An in-vitro study of the cytotoxicity and
+an understanding of the specific pathway of cellular uptake will enable
+manipulation of conditions for optimal cellular uptake of SPIONs for targeted
+therapy. The objective of the present study was to identify the endocytotic
+pathway through which the SPIONs are taken up by C6 glioma cells. The cells
+were pre-incubated with different concentrations of pharmacological inhibitors
+and then exposed to SPIONs for a few hours. The endocytosed particles were
+localized and quantitatively estimated using Perl's or Prussian Blue reaction.
+There was significant reduction in the uptake of SPIONs when incubated with the
+inhibitor indicating the uptake of nanoparticles is being inhibited. This
+reduction in SPION uptake was found to be dependent on the concentration of the
+inhibitors and also the nature of the inhibitors. By a systematic study of
+choosing various inhibitors, the data can be narrowed down to the final pathway
+that may be involved in the SPION uptake. The present preliminary investigation
+is expected to provide insight of testing the possible mechanisms with
+complementary techniques.",1801.04825v1
+2018-09-21,Electronic Spin transition in FeO$_{2}$: evidence for Fe(II) with peroxide O$_{2}^{2-}$,"The discovery of FeO$_{2}$ containing more oxygen than hematite
+(Fe$_{2}$O$_{3}$) that was previously believed to be the most oxygen rich iron
+compounds, has important implications on the study of the deep lower mantle
+compositions. Compared to other iron compounds, there are limited reports on
+FeO$_{2}$ making studies of its physical properties of great interest in
+fundamental condensed matter physics and geoscience. Even the oxidation state
+of Fe in FeO$_{2}$ is the subject of debate in theoretical works and there have
+not been reports from experimental electronic and magnetic properties
+measurements. Here, we report the pressure-induced spin state transition from
+synchrotron experiments and our computational results explain the underlying
+mechanism. Using density functional theory and dynamical mean field theory, we
+calculated spin states of Fe with volume and Hubbard interaction $U$ change,
+which clearly demonstrate that Fe in FeO$_{2}$ consists of Fe(II) and peroxide
+O$_{2}^{2-}$. Our study suggests that localized nature of both Fe 3$d$ orbitals
+and O$_{2}$ molecular orbitals should be correctly treated for unveiling the
+structural and electronic properties of FeO$_{2}$.",1809.07969v1
+2018-10-18,Andreev reflection at the interface with an oxide in the quantum Hall regime,"Quantum Hall/superconductor junctions have been an attractive topic as the
+two macroscopically quantum states join at the interface. Despite longstanding
+efforts, however, experimental understanding of this system has not been
+settled yet. One of the reasons is that most semiconductors hosting
+high-mobility two-dimensional electron systems (2DES) usually form Schottky
+barriers at the metal contacts, preventing efficient proximity between the
+quantum Hall edge states and Cooper pairs. Only recently have relatively
+transparent 2DES/superconductor junctions been investigated in graphene. In
+this study, we propose another material system for investigating
+2DES/superconductor junctions, that is ZnO-based heterostrcuture. Due to the
+ionic nature of ZnO, a Schottky barrier is not effectively formed at the
+contact with a superconductor MoGe, as evidenced by the appearance of Andreev
+reflection at low temperatures. With applying magnetic field, while clear
+quantum Hall effect is observed for ZnO 2DES, conductance across the junction
+oscillates with the filling factor of the quantum Hall states. We find that
+Andreev reflection is suppressed in the well developed quantum Hall regimes,
+which we interpret as a result of equal probabilities of normal and Andreev
+reflections as a result of multiple Andreev reflection at the
+2DES/superconductor interface.",1810.08198v1
+2019-06-15,Symmetry-Breaking Polymorphous Descriptions for Complex Materials without Interelectronic U,"Correlated materials with open-shell d- and f-ions having degenerate band
+edge states show a rich variety of interesting properties ranging from
+metal-insulator transition to unconventional superconductivity. The textbook
+view for the electronic structure of these materials is that mean-field
+approaches are inappropriate, as the interelectronic interaction U is required
+to open a band gap between the occupied and unoccupied degenerate states while
+retaining symmetry. We show that the latter scenario often defining what Mott
+insulators are, is in fact not needed for the 3d binary oxides MnO, FeO, CoO,
+and NiO. The mean-field band theory can indeed lift such degeneracies in the
+binaries when nontrivial unit cell representations (polymorphous networks) are
+allowed to break symmetries, in conjunction with a recently developed
+non-empirical exchange and correlation density-functional without an on-site
+interelectronic interaction U. We explain how density-functional theory (DFT)
+in the polymorphous representation achieves band gap opening in correlated
+materials through a separate mechanism to the Mott-Hubbard approach. We show
+the method predicts magnetic moments and gaps for the four binary monoxides in
+both the antiferromagnetic and paramagnetic phases, offering an effective
+alternative to symmetry-conserving approaches for studying a range of
+functionalities in open d- and f-shell complex materials.",1906.06467v3
+2019-06-17,Imaging Antiferromagnetic Domains in Nickel-oxide Thin Films by Magneto-optical Voigt Effect,"Recent demonstrations of electrical detection and manipulation of
+antiferromagnets (AFMs) have opened new opportunities towards robust and
+ultrafast spintronics devices. However, it is difficult to establish the
+connection between the spin-transport behavior and the microscopic AFM domain
+states due to the lack of the real-time AFM domain imaging technique under the
+electric field. Here we report a significant Voigt rotation up to 60 mdeg in
+thin NiO(001) films at room temperature. Such large Voigt rotation allows us to
+directly observe AFM domains in thin-film NiO by utilizing a wide-field optical
+microscope. Further complementary XMLD-PEEM measurement confirms that the Voigt
+contrast originates from the NiO AFM order. We examine the domain pattern
+evolution at a wide range of temperature and with the application of external
+magnetic field. Comparing to large-scale-facility techniques such as the X-ray
+photoemission electron microscopy, the use with a wide-field, tabletop optical
+imaging method enables straightforward access to domain configurations of
+single-layer AFMs.",1906.06844v2
+2019-07-28,Field-dependent nonlinear surface resistance and its optimization by surface nano-structuring in superconductors,"We propose a theory of nonlinear surface resistance of a dirty superconductor
+in a strong radio-frequency (RF) field, taking into account magnetic and
+nonmagnetic impurities, finite quasiparticle lifetimes, and a thin
+proximity-coupled normal layer characteristic of the oxide surface of many
+materials. The Usadel equations were solved to obtain the quasiparticle density
+of states (DOS) and the low-frequency surface resistance $R_s$ as functions of
+the RF field amplitude $H_0$. It is shown that the interplay of the broadening
+of the DOS peaks and a decrease of a quasiparticle gap caused by the RF
+currents produces a minimum in $R_s(H_0)$ and an extended rise of the quality
+factor $Q(H_0)$ with the RF field. Paramagnetic impurities shift the minimum in
+$R_s(H_0)$ to lower fields and can reduce $R_s(H_0)$ in a wide range of $H_0$.
+Subgap states in the DOS can give rise to a residual surface resistance while
+reducing $R_s$ at higher temperatures. A proximity-coupled normal layer at the
+surface can shift the minimum in $R_s(H_0)$ to either low and high fields and
+can reduce $R_s$ below that of an ideal surface. The theory shows that the
+behavior of $R_s(H_0)$ changes as the temperature and the RF frequency are
+increased, and the field dependence of $Q(H_0)$ can be very sensitive to the
+materials processing. Our results suggest that the nonlinear RF losses can be
+minimized by tuning pairbreaking effects at the surface using impurity
+management or surface nanostructuring.",1907.12040v1
+2019-09-02,Electronic structure of interstitial hydrogen in In-Ga-Zn-O semiconductor simulated by muon,"We report on the local electronic structure of interstitial muon (Mu) as
+pseudo-hydrogen in In-Ga-Zn oxide (IGZO) semiconductor studied by muon spin
+rotation/relaxation ($\mu$SR) experiment. In polycrystalline (c-) IGZO, it is
+inferred that Mu is in a diamagnetic state, where the $\mu$SR time spectra
+under zero external field is perfectly described by the Gaussian Kubo-Toyabe
+relaxation function with the linewidth $\Delta$ serving as a sensitive measure
+for the random local fields from In/Ga nuclear magnetic moments. The magnitude
+of $\Delta$ combined with the density functional theory calculations for H (to
+mimic Mu) suggests that Mu occupies Zn-O bond-center site (Mu$_{\rm BC}$)
+similar to the case in crystalline ZnO. This implies that the diamagnetic state
+in c-IGZO corresponds to Mu$_{\rm BC}^+$, thus serving as an electron donor. In
+amorphous (a-) IGZO, the local Mu structure in as-deposited films is nearly
+identical with that in c-IGZO, suggesting Mu$_{\rm BC}^+$ for the electronic
+state. In contrast, the diamagnetic signal in heavily hydrogenated a-IGZO films
+exhibits the Lorentzian Kubo-Toyabe relaxation, implying that Mu accompanies
+more inhomogeneous distribution of the neighboring nuclear spins that may
+involve Mu$^-$H$^-$-complex state in an oxygen vacancy.",1909.00503v1
+2019-09-11,Full control of Co valence in isopolar LaCoO3 / LaTiO3 perovskite heterostructures via interfacial engineering,"We report charge-transfer up to a single electron per interfacial unit cell
+across non-polar heterointerfaces from the Mott insulator LaTiO3 to the charge
+transfer insulator LaCoO3. In high-quality bi- and tri-layer systems grown
+using pulsed laser deposition, soft X-ray absorption, dichroism and STEM-EELS
+are used to probe the cobalt 3d-electron count and provide an element-specific
+investigation of the magnetic properties. The experiments prove a
+deterministically-tunable charge transfer process acting in the LaCoO3 within
+three unit cells of the heterointerface, able to generate full conversion to
+3d7 divalent Co, which displays a paramagnetic ground state. The number of
+LaTiO3 / LaCoO3 interfaces, the thickness of an additional ""break"" layer
+between the LaTiO3 and LaCoO3, and the LaCoO3 film thickness itself in
+tri-layers provide a trio of sensitive control knobs for the charge transfer
+process, illustrating the efficacy of O2p-band alignment as a guiding principle
+for property design in complex oxide heterointerfaces.",1909.05247v1
+2019-09-13,Gate-tunable spin exclusive or operation in a silicon-based spin device at room temperature,"Room temperature operation of a spin exclusive or (XOR) gate was demonstrated
+in lateral spin valve devices with nondegenerate silicon (Si) channels. The
+spin XOR gate is a fundamental part of the magnetic logic gate (MLG) that
+enables reconfigurable and nonvolatile NAND or OR operation in one device. The
+device for the spin XOR gate consists of three iron (Fe)/cobalt (Co)/magnesium
+oxide (MgO) electrodes, i.e., two input and one output electrodes. Spins are
+injected into the Si channel from the input electrodes whose spin angular
+momentum corresponds to the binary input 1 or 0. The spin drift effect is
+controlled by a lateral electric field in the Si channel to adjust the spin
+accumulation voltages under two different parallel configurations,
+corresponding to (1, 1) and (0, 0), so that they exhibit the same value. As a
+result, the spin accumulation voltage detected by the output electrode exhibits
+three different voltages, represented by an XOR gate. The one-dimensional spin
+drift-diffusion model clearly explains the obtained XOR behavior. Charge
+current detection of the spin XOR gate is also demonstrated. The detected
+charge current has a maximum of 0.94 nA, the highest value in spin XOR gates
+reported thus far. Furthermore, gate voltage modulation of the spin XOR gate is
+also demonstrated, which enables operation of multiple MLG devices.",1909.06080v1
+2019-10-04,Large Magnetoelectric Response in Sr2IrO4/SrTiO3 superlattices with non-equivalent interfaces,"Large magnetoelectric response in thin films is highly desired for
+high-throughput and high-density microelectronic applications. However, the d0
+rule in single-phase compounds usually results in a weak interaction between
+ferroelectric and magnetic orders; the magnetoelectric coupling via elastic
+resonance in composites restricts their thin-film integration in broadband.
+Here, we effectuate a concurrence of ferroelectric-like and antiferromagnetic
+phase transitions in Sr2IrO4/SrTiO3 superlattices by artificial design
+periodically non-equivalent interfaces, where a maximum magnetoelectric
+coefficient of ~980 mV cm-1 Oe-1 can be measured. Evidenced by synchrotron
+X-ray absorption and electron energy loss spectroscopies, a lopsided electron
+occupation occurs at the interfacial Ti ions. From perturbative calculations
+and numerical results, a strong coupling of antiferromagnetism and asymmetric
+electron occupation mediated by spin-orbit interaction leads to a large bulk
+magnetoelectric response. This atomic tailoring of the quantum order parameters
+in 3d and 5d oxides provides an alternative pathway towards strong
+magnetoelectric effects with thin-film integrations.",1910.01787v1
+2020-01-26,Electronically driven spin-reorientation transition of the correlated polar metal Ca$_3$Ru$_2$O$_7$,"Polar distortions in solids give rise to the well-known functionality of
+switchable macroscopic polarisation in ferroelectrics and, when combined with
+strong spin-orbit coupling, can mediate giant spin splittings of electronic
+states. While typically found in insulators, ferroelectric-like distortions can
+remain robust against increasing itineracy, giving rise to so-called ""polar
+metals"". Here, we investigate the temperature-dependent electronic structure of
+Ca$_3$Ru$_2$O$_7$, a correlated oxide metal in which octahedral tilts and
+rotations combine to mediate pronounced polar distortions. Our angle-resolved
+photoemission measurements reveal the destruction of a large hole-like Fermi
+surface upon cooling through a coupled structural and spin-reorientation
+transition at 48 K, accompanied by a sudden onset of quasiparticle coherence.
+We demonstrate how these result from band hybridisation mediated by a hidden
+Rashba-type spin-orbit coupling. This is enabled by the bulk structural
+distortions and unlocked when the spin reorients perpendicular to the local
+symmetry-breaking potential at the Ru sites. We argue that the electronic
+energy gain associated with the band hybridisation is actually the key driver
+for the phase transition, reflecting a delicate interplay between spin-orbit
+coupling and strong electronic correlations, and revealing a new route to
+control magnetic ordering in solids.",2001.09499v1
+2020-04-11,Understanding the mechanism of oxygen evolution reaction (OER) with the consideration of spin,"Oxygen evolution reaction (OER) with intractable high overpotential is the
+rate-limiting step for rechargeable metal-air battery, water electrolysis
+systems, and solar fuels devices. There exists a spin state transition from
+spin singlet OH-/H2O reactant to spin triplet O2 product, which has not
+received enough attention yet. In this perspective, we attempt to retrospect
+electron behaviours during the whole OER process, with the consideration of
+spin attribute. Regardless of the adopted mechanisms by different
+electrocatalysts, for example, adsorbate evolution mechanism (AEM) or lattice
+oxygen mechanism (LOM), the underlying rationale is that active sites have to
+extract three in four electrons with the same spin direction before the
+formation of O=O. This spin-sensitive nature of OER superimposes additional
+high requirements on the electrocatalysts, especially on the spin structure, to
+compliment the fast electron transfer in the interface with spin selection and
+smoothly delivery afterwards. When optimizing the geometric and electronic
+structures catering for the spin-sensitive OER, awareness of the couplings
+between spin, charge, orbital and lattice is necessary. Some spin-correlated
+physical properties, such as (1) crystal field, (2) coordination, (3)
+oxidation, (4) bonding, (5) eg electron number, (6) conductivity and (7)
+magnetism, are also discussed briefly. It is hoped that our perspective could
+shed lights on the underlying physics of the slow kinetics of OER, providing a
+rational guidance for more effective energy conversion electrocatalysts
+designs.",2004.05326v1
+2020-12-11,Isotropic Pauli-Limited Superconductivity in the Infinite Layer Nickelate Nd$_{0.775}$Sr$_{0.225}$NiO$_{2}$,"The recent observation of superconductivity in thin film infinite-layer
+nickelates$^{1-3}$ offers a different angle to investigate superconductivity in
+layered oxides$^{4}$. A wide range of candidate models have been
+proposed$^{5-10}$, emphasizing single- or multi-orbital electronic structure,
+Kondo or Hund's coupling, and analogies to cuprates. Clearly, further
+experimental characterization of the superconducting state is needed to develop
+a full understanding of the nickelates. Here we use magnetotransport
+measurements to probe the superconducting anisotropy in
+Nd$_{0.775}$Sr$_{0.225}$NiO$_{2}$. We find that the upper critical field is
+surprisingly isotropic at low temperatures despite the layered crystal
+structure. In a magnetic field the superconductivity is strongly Pauli-limited,
+such that the paramagnetic effect dominates over orbital de-pairing. Underlying
+this isotropic response is a substantial anisotropy in the superconducting
+coherence length, which is at least four times longer in-plane than
+out-of-plane. A prominent low-temperature upturn in the upper critical field
+indicates the presence of an unconventional ground state.",2012.06560v1
+2020-12-18,Methodology for In-flight Flat-field Calibration of the Lyman-alpha Solar Telescope (LST),"Flat-field reflects the non-uniformity of the photometric response at the
+focal plane of an instrument, which uses digital image sensors, such as Charge
+Coupled Device (CCD) and Complementary Metal-Oxide-Semiconductor (CMOS). This
+non-uniformity must corrected before being used for scientific research. In
+this paper, we assess various candidate methods via simulation using available
+data so as to figure the in-flight flat-field calibration methodology for the
+Lyman-alpha Solar Telescope (LST). LST is one of the payloads for the Advanced
+Space-based Solar Observatory (ASO-S) mission and consists of three
+instruments: a White-light Solar Telescope (WST), a Solar Disk Imager (SDI) and
+a dual-waveband Solar Corona Imager (SCI). In our simulations, data from the
+Helioseismic and Magnetic Imager (HMI) and Atmospheric Imaging Assembly (AIA)
+onboard the Solar Dynamics Observatory (SDO) mission are used. Our results show
+that the normal KLL method is appropriate for in-flight flat-field calibration
+of WST and implementing a transmissive diffuser is applicable for SCI. For the
+in-flight flat-field calibration of SDI, we recommend the KLL method with
+off-pointing images with defocused resolution of around 18"", and use the local
+correlation tracking (LCT) algorithm instead of limb-fitting to determine the
+relative dis-placements between different images.",2012.10110v1
+2021-01-12,Non-volatile reconfigurable spin logic device: parallel operations,"A new proposal is given for designing a non-volatile, completely spin logic
+device, that can be reprogrammed for different functional classical logical
+operations. We use the concept of bias driven spin dependent circular current
+and current induced magnetic field in a quantum ring under asymmetric
+ring-to-electrode interface configuration to implement all the Boolean
+operations. We extend our idea to build two kinds of parallel computing
+architectures for getting parallelized operations, all at a particular time.
+For one case, different kinds of parallel operations are performed in a single
+device, whereas in the other type all the possible inputs of a logic gate are
+processed in parallel and all the outputs are read simultaneously. The
+performance and reliability are investigated in terms of power, delay and
+power-delay-product and finally the system temperature. We find that both the
+individual and simultaneous logic operations studied here are much superior
+compared to the operations performed in different conventional logic families
+like complementary metal oxide semiconductor logic, transistor-transistor
+logic, etc. The key advantage is that we can perform several logic operations,
+as many as we wish, repeating the same or different logic gates using a single
+setup, which indeed reduces wiring in the circuits and hence consumes much less
+power. Our analysis can be utilized to design optimized logic circuits at
+nano-scale level.",2101.04311v1
+2012-05-25,Anisotropic ferromagnetism in carbon doped zinc oxide from first-principles studies,"A density functional theory study of substitutional carbon impurities in ZnO
+has been performed, using both the generalized gradient approximation (GGA) and
+a hybrid functional (HSE06) as exchange-correlation functional. It is found
+that the non-spinpolarized C$_\mathrm{Zn}$ impurity is under almost all
+conditions thermodynamically more stable than the C$_\mathrm{O}$ impurity which
+has a magnetic moment of $2\mu_{\mathrm{B}}$, with the exception of very O-poor
+and C-rich conditions. This explains the experimental difficulties in sample
+preparation in order to realize $d^{0}$-ferromagnetism in C-doped ZnO. From GGA
+calculations with large 96-atom supercells, we conclude that two
+C$_\mathrm{O}$-C$_\mathrm{O}$ impurities in ZnO interact ferromagnetically, but
+the interaction is found to be short-ranged and anisotropic, much stronger
+within the hexagonal $ab$-plane of wurtzite ZnO than along the c-axis. This
+layered ferromagnetism is attributed to the anisotropy of the dispersion of
+carbon impurity bands near the Fermi level for C$_{\mathrm{O}}$ impurities in
+ZnO. From the calculated results, we derive that a C$_{\mathrm{O}}$
+concentration between 2% and 6% should be optimal to achieve
+$d^{0}$-ferromagnetism in C-doped ZnO.",1205.5830v1
+2017-09-20,Optical time reversal from time-dependent Epsilon-Near-Zero media,"Materials with a spatially uniform but temporally varying optical response
+have applications ranging from magnetic field-free optical isolators to
+fundamental studies of quantum field theories. However, these effects typically
+become relevant only for time-variations oscillating at optical frequencies,
+thus presenting a significant hurdle that severely limits the realisation of
+such conditions. Here we present a thin-film material with a permittivity that
+pulsates (uniformly in space) at optical frequencies and realises a
+time-reversing medium of the form originally proposed by Pendry [Science 322,
+71 (2008)]. We use an optically pumped, 500 nm thick film of epsilon-near-zero
+(ENZ) material based on Al-doped zinc oxide (AZO). An incident probe beam is
+both negatively refracted and time-reversed through a reflected
+phase-conjugated beam. As a result of the high nonlinearity and the refractive
+index that is close to zero, the ENZ film leads to time reversed beams
+(simultaneous negative refraction and phase conjugation) with near-unit
+efficiency and greater-than-unit internal conversion efficiency. The ENZ
+platform therefore presents the time-reversal features required e.g. for
+efficient subwavelength imaging, all-optical isolators and fundamental quantum
+field theory studies.",1709.06972v1
+2017-09-27,Pressure induced spin crossover in disordered α-LiFeO2,"Structural, magnetic and electrical-transport properties of {\alpha}-LiFeO2,
+crystallizing in the rock salt structure with random distribution of Li and Fe
+ions, have been studied by synchrotron X-ray diffraction, 57Fe M\""ossbauer
+spectroscopy and electrical resistance measurements at pressures up to 100 GPa
+using diamond anvil cells. It was found that the crystal structure is stable at
+least to 82 GPa, though a significant change in compressibility has been
+observed above 50 GPa. The changes in the structural properties are found to be
+on a par with a sluggish Fe3+ high- to low-spin (HS-LS) transition (S=5/2 to
+S=1/2) starting at 50 GPa and not completed even at ~100 GPa. The HS-LS
+transition is accompanied by an appreciable resistance decrease remaining a
+semiconductor up to 115 GPa and is not expected to be metallic even at about
+200 GPa. The observed feature of the pressure-induced HS-LS transition is not
+an ordinary behavior of ferric oxides at high pressures. The effect of Fe3+
+nearest and next nearest neighbors on the features of the spin crossover is
+discussed.",1709.09680v1
+2017-10-31,Spin susceptibility of charge ordered YBa2Cu3Oy across the upper critical field,"The value of the upper critical field Hc2, a fundamental characteristic of
+the superconducting state, has been subject to strong controversy in high-Tc
+copper-oxides. Since the issue has been tackled almost exclusively by
+macroscopic techniques so far, there is a clear need for local-probe
+measurements. Here, we use 17O NMR to measure the spin susceptibility
+$\chi_{spin}$ of the CuO2 planes at low temperature in charge ordered
+YBa2Cu3Oy. We find that $\chi_{spin}$ increases (most likely linearly) with
+magnetic field H and saturates above field values ranging from 20 to 40 T. This
+result is consistent with Hc2 values claimed by G. Grissonnanche et al. [Nat.
+Commun. 5, 3280 (2014)] and with the interpretation that the
+charge-density-wave (CDW) reduces Hc2 in underdoped YBa2Cu3Oy. Furthermore, the
+absence of marked deviation in $\chi_{spin}(H)$ at the onset of long-range CDW
+order indicates that this Hc2 reduction and the Fermi-surface reconstruction
+are primarily rooted in the short-range CDW order already present in zero
+field, not in the field-induced long-range CDWorder. Above Hc2, the relatively
+low values of $\chi_{spin}$ at T=2 K show that the pseudogap is a ground-state
+property, independent of the superconducting gap.",1711.00109v1
+2017-11-21,Superconducting Gatemon Qubit based on a Proximitized Two-Dimensional Electron Gas,"The coherent tunnelling of Cooper pairs across Josephson junctions (JJs)
+generates a nonlinear inductance that is used extensively in quantum
+information processors based on superconducting circuits, from setting qubit
+transition frequencies and interqubit coupling strengths, to the gain of
+parametric amplifiers for quantum-limited readout. The inductance is either set
+by tailoring the metal-oxide dimensions of single JJs, or magnetically tuned by
+parallelizing multiple JJs in superconducting quantum interference devices
+(SQUIDs) with local current-biased flux lines. JJs based on
+superconductor-semiconductor hybrids represent a tantalizing all-electric
+alternative. The gatemon is a recently developed transmon variant which employs
+locally gated nanowire (NW) superconductor-semiconductor JJs for qubit control.
+Here, we go beyond proof-of-concept and demonstrate that semiconducting
+channels etched from a wafer-scale two-dimensional electron gas (2DEG) are a
+suitable platform for building a scalable gatemon-based quantum computer. We
+show 2DEG gatemons meet the requirements by performing voltage-controlled
+single qubit rotations and two-qubit swap operations. We measure qubit
+coherence times up to ~2 us, limited by dielectric loss in the 2DEG host
+substrate.",1711.07665v3
+2018-06-11,Towards understanding the special stability of ${\text{SrCo}\text{O}_{2.5}}$ and ${\text{HSrCo}\text{O}_{2.5}}$,"Reversible hydrogen incorporation was recently attested [N. Lu, $\textit{et
+al.}$, Nature $\textbf{546}$, 124 (2017)] in ${\text{SrCo}\text{O}_{2.5}}$, the
+brownmillerite phase (BM) of strontium cobalt oxide (SCO), opening new avenues
+in catalysis and energy applications. However, existing theoretical studies of
+BM-SCO are insufficient, and that of ${\text{HSrCo}\text{O}_{2.5}}$, the
+newly-reported hydrogenated SCO (H-SCO), is especially scarce. In this work, we
+demonstrate how the electron-counting model (ECM) can be used in understanding
+the phases, particularly in explaining the stability of the oxygen-vacancy
+channels (OVCs), and in examining the Co valance problem. Using
+density-functional theoretical (DFT) methods, we analyze the crystalline,
+electronic, and magnetic structures of BM- and H-SCO. Based on our structure
+search, we discovered stable phases with large bandgaps (> 1 eV) for both
+BM-SCO and H-SCO, agreeing better with experiments on the electronic
+structures. Our calculations also indicate limited charge transfer from H to O
+that may explain the special stability of the H-SCO phase and the reversibility
+of H incorporation observed in experiments. In contrary to the initial study,
+our calculation also suggests intrinsic antiferromagnetism (AFM) of H-SCO,
+showing how the measured ferromagnetism (FM) has possible roots in hole doping.",1806.03917v2
+2018-06-25,A materials informatics approach to the identification of one-band correlated materials analogous to the cuprates,"One important yet exceedingly rare property of the cuprate high-temperature
+superconductors is the presence of a single correlated $d$ band in the
+low-energy spectrum, leading to the one-band Hubbard model as the minimal
+description. In order to search for materials with interesting strong
+correlation physics as well as possible benchmark systems for the one-band
+Hubbard model, here we present a new approach to find one-band correlated
+materials analogous to the cuprates by leveraging the emerging area of
+materials informatics. Using the composition, structure, and formation energy
+of more than half a million real and hypothetical inorganic crystalline
+materials in the Open Quantum Materials Database, we search for synthesizable
+materials whose nominal transition metal $d$ electron count and crystal field
+are compatible with achieving an isolated half-filled $d$ band. Five Cu
+compounds, including bromide, oxide, selenate, and pyrophosphate chemistries,
+are shown to successfully achieve the one-band electronic structure based on
+density functional theory band structure calculations. Further calculations
+including magnetism and explicit on-site Coulomb interaction reveal significant
+evidence for strong correlation physics in the five candidates, including Mott
+insulating behavior and antiferromagnetism. The success of our data-driven
+approach to discovering new correlated materials opens up new avenues to design
+and discover materials with rare electronic properties.",1806.09662v1
+2018-07-09,High tunability of the transport properties in macroscopically in-plane modulated two-dimensional system,"Gate-controllable two dimensional systems with in-plane modulation of
+properties could serve as highly tunable effective media. Intuitively, such
+systems may bring novel functionality provided that the period of the lateral
+modulation is much less than the relevant scattering lengths (mean free path,
+coherence length etc.). Our work experimentally demonstrates the opposite,
+disordered limit of such system, defined in the macroscopically modulated
+metal-oxide-semiconductor structure. The system consists of parent
+two-dimensional gas with periodic array of islands (dots/antidots), filled with
+two-dimensional gas of different density, and surrounded by depletion regions
+(shells). Carrier densities of both parent gas and islands are controlled by
+two independent gate electrodes, allowing us to explore a rich phase diagram of
+low-temperature transport properties of this modulated two-dimensional system,
+resembling various transport regimes: insulating, shell-dominated,
+gas-dominated, island-dominated. These regimes can be identified by various
+Hall resistance and its magnetic field dependence, temperature dependencies of
+the resistivity, and Shubnikov-de Haas patterns. We also suggest the
+theoretical approach for description of such inhomogeneous but periodical
+systems. Theory based on the classical mean field approach qualitatively
+describes our system as theoretical dependencies reproduce the main features of
+the experimental behavior of the effective Hall concentration from gate
+voltage. Thus, our work demonstrates feasibility of the macroscopically
+inhomogeneous two-dimensional system as a tunable platform for novel physics
+and proposes the approach for the theoretical description of such systems.",1807.03421v2
+2018-07-13,Disentangling orbital and spin exchange interactions for Co$^{2+}$ on a rocksalt lattice,"Neutron spectroscopy was applied to study the magnetic interactions of
+orbitally degenerate Co$^{2+}$ on a host MgO rocksalt lattice where no long
+range spin or orbital order exists. The paramagnetic nature of the substituted
+monoxide Co$_{0.03}$Mg$_{0.97}$O allows for the disentanglement of
+spin-exchange and spin-orbit interactions. By considering the prevalent
+excitations from Co$^{2+}$ spin pairs, we extract 7 exchange constants out to
+the fourth coordination shell. An antiferromagnetic next nearest neighbor
+180$^{\circ}$ exchange interaction is dominant, however dual ferromagnetic and
+antiferromagnetic interactions are observed for pairings with other pathways.
+These interactions can be understood in terms of a combination of orbital
+degeneracy in the $t_{2g}$ channel and the Goodenough-Kanamori-Anderson (GKA)
+rules. Our work suggests that such a hierarchy of exchange interactions exists
+in transition metal-based oxides with a $t_{2g}$ orbital degeneracy.",1807.05012v2
+2018-08-11,Novel Superconducting SrSnP with Strong Sn-P Antibonding Interaction: Is the Sn Atom Single or Mixed Valent?,"The large single crystals of SrSnP were prepared using Sn self-flux method.
+The superconductivity in the tetragonal SrSnP is observed with the critical
+temperature of ~2.3 K. The results of a crystallographic analysis,
+superconducting characterization, and theoretical assessment of tetragonal
+SrSnP are presented. The SrSnP crystallizes in the CaGaN structure type with
+space group P4/nmm (S.G.129, Pearson symbol tP6) according to the single
+crystal X-ray diffraction characterization. A combination of magnetic
+susceptibility, resistivity, and heat capacity measurements confirms the bulk
+superconductivity with Tc = 2.3(1) K in SrSnP. According to the X-ray
+photoelectron spectroscopy (XPS) measurement, the assignments of Sr2+ and P3-
+are consistent with the chemical valence electron balance principles. Moreover,
+it is highly likely that Sn atom has only one unusual oxidation state.
+First-principles calculations indicate the bands around Fermi level are
+hybridized among Sr-d, Sn-p, and P-p orbitals. The strong Sn-P and Sr-P
+interactions pose as keys to stabilize the crystallographic structure and
+induce the superconductivity, respectively. The physics-based electronic and
+phononic calculations are consistent with the molecular viewpoint. After
+including the spin-orbit coupling (SOC) into the calculation, the band
+degeneracies at gamma-point in the first Brillouin zone (BZ) split into two
+bands, which yield to the van Hove singularities around Fermi level.",1808.03828v1
+2018-08-15,Chirality and intrinsic dissipation of spin modes in two-dimensional electron liquids,"We review recent theoretical and experimental developments concerning
+collective spin excitations in two-dimensional electron liquid (2DEL) systems,
+with particular emphasis on the interplay between many-body and spin-orbit
+effects, as well as the intrinsic dissipation due to the spin-Coulomb drag.
+Historically, the experimental realization of 2DELs in silicon inversion layers
+in the 60s and 70s created unprecedented opportunities to probe subtle quantum
+effects, culminating in the discovery of the quantum Hall effect. In the
+following years, high quality 2DELs were obtained in doped quantum wells made
+in typical semiconductors like GaAs or CdTe. These systems became important
+test beds for quantum many-body effects due to Coulomb interaction, spin
+dynamics, spin-orbit coupling, effects of applied magnetic fields, as well as
+dissipation mechanisms. Here we focus on the recent results involving chiral
+effects and intrinsic dissipation of collective spin modes: these are not only
+of fundamental interest but also important towards demonstrating new concepts
+in spintronics. Moreover, new realizations of 2DELs are emerging beyond
+traditional semiconductors, for instance in multilayer graphene, oxide
+interfaces, dichalcogenide monolayers, and many more. The concepts discussed in
+this review will be relevant also for these emerging systems.",1808.05266v2
+2018-08-17,Yang-Mills Structure for Electron-Phonon Interactions,"This work presents a method of grouping the electron spinors and the acoustic
+phonon modes of polar crystals such as metal oxides into an SU(2) gauge theory.
+The gauge charge is the electron spin, which is assumed to couple to the
+transverse acoustic phonons on the basis of spin ordering phenomena in crystals
+such as V$_{2}$O$_{3}$ and VO$_{2}$, while the longitudinal mode is neutral. A
+generalization the Peierls mechanism is presented based on the discrete gauge
+invariance of crystals and the corresponding Ward-Takahashi identity. The
+introduction of a band index violates the Ward-Takahashi identity for interband
+transitions resulting in a longitudinal component appearing in the upper phonon
+band. Thus both the spinors and the vector bosons acquire mass and a crystal
+with an electronic band gap and optical phonon modes results. In the limit that
+the coupling of bosons charged under the SU(2) gauge group goes to zero,
+breaking the electron U(1) symmetry recovers the BCS mechanism. In the limit
+that the neutral boson decouples, a Cooper instability mediated by spin-wave
+exchange results from symmetry breaking, i.e. unconventional superconductivity
+mediated by magnetic interactions.",1808.05769v2
+2018-12-15,Anomalous behavior of the quasi-one-dimensional quantum material Na$_{2}$OsO$_{4}$ at high pressure,"Na$_{2}$OsO$_{4}$ is an unusual quantum material that, in contrast to the
+common 5${d}^{2}$ oxides with spins = 1, owns a magnetically silent ground
+state with spin = 0 and a band gap at Fermi level attributed to a distortion in
+the OsO$_{6}$ octahedral sites. In this semiconductor, our low-temperature
+electrical transport measurements indicate an anomaly at 6.3 K with a power-law
+behavior inclining through the semiconductor-to-metal transition observed at 23
+GPa. Even more peculiarly, we discover that before this transition, the
+material becomes more insulating instead of merely turning into a metal
+according to the conventional wisdom. To investigate the underlying mechanisms,
+we applied experimental and theoretical methods to examine the electronic and
+crystal structures comprehensively, and conclude that the enhanced insulating
+state at high pressure originates from the enlarged distortion of the
+OsO$_{6}$. It is such a distortion that widens the band gap and decreases the
+electron occupancy in Os's ${t}_{2g}$ orbital through an interplay of the
+lattice, charge, and orbital in the material, which is responsible for the
+changes observed in our experiments.",1812.06256v3
+2018-12-15,Observation of high-Tc superconductivity in inhomogeneous combinatorial ceramics,"A single-sample synthesis concept based on multi-element ceramic samples can
+produce a variety of local products. When applied to cuprate superconductors
+(SC), statistical modelling predicts the occurrence of possible compounds in a
+concentration range of about 50 ppm. In samples with such low concentrations,
+determining which compositions are superconducting is a challenging task and
+requires local probes or separation techniques. Here, we report results from
+samples with seven components: BaO2, CaCO3, SrCO3, La2O3, PbCO3, ZrO2 and CuO
+oxides and carbonates, starting from different grain sizes. The reacted
+ceramics show different phases, particular grain growth, as well as variations
+in homogeneity and superconducting properties. High-Tc superconductivity up to
+118 K was found. Powder x-ray diffraction (XRD) in combination with
+energy-dispersive spectroscopy (EDS), scanning transmission electron microscopy
+(STEM) can assign Pb1223 and (Sr,Ca,Ba)0.7-1.0CuO2 phases in inhomogeneous
+samples milled with 10 mm ball sizes. Rather uniform samples featuring strong
+grain growth were obtained with 3 mm ball sizes, resulting in Tc =70 K
+superconductivity of the La(Ba,Ca)2Cu3Ox based phase. Scanning SQUID microscopy
+(SSM) establishes locally formed superconducting areas at a level of a few
+microns in inhomogeneous superconducting particles captured by a magnetic
+separation technique. The present results demonstrate a new synthetic approach
+for attaining high-Tc superconductivity in compounds without Bi, Tl, Hg, or the
+need for high-pressure synthesis.",1812.06273v1
+2019-01-19,Resolving the nature of electronic excitations in resonant inelastic x-ray scattering,"The study of elementary bosonic excitations is essential toward a complete
+description of quantum electronic solids. In this context, resonant inelastic
+X-ray scattering (RIXS) has recently risen to becoming a versatile probe of
+electronic excitations in strongly correlated electron systems. The nature of
+the radiation-matter interaction endows RIXS with the ability to resolve the
+charge, spin and orbital nature of individual excitations. However, this
+capability has been only marginally explored to date. Here, we demonstrate a
+systematic method for the extraction of the character of excitations as
+imprinted in the azimuthal dependence of the RIXS signal. Using this novel
+approach, we resolve the charge, spin, and orbital nature of elastic
+scattering, (para-)magnon/bimagnon modes, and higher energy dd excitations in
+magnetically-ordered and superconducting copper-oxide perovskites (Nd2CuO4 and
+YBa2Cu3O6.75). Our method derives from a direct application of scattering
+theory, enabling us to deconstruct the complex scattering tensor as a function
+of energy loss. In particular, we use the characteristic tensorial nature of
+each excitation to precisely and reliably disentangle the charge and spin
+contributions to the low energy RIXS spectrum. This procedure enables to
+separately track the evolution of spin and charge spectral distributions in
+cuprates with doping. Our results demonstrate a new capability that can be
+integrated into the RIXS toolset, and that promises to be widely applicable to
+materials with intertwined spin, orbital, and charge excitations.",1901.06583v1
+2019-02-04,Auxiliary Field Quantum Monte Carlo for Multiband Hubbard Models: Controlling the Sign and Phase Problems to Capture Hund's Physics,"In the study of strongly-correlated, many-electron systems, the Hubbard
+Kanamori (HK) model has emerged as one of the prototypes for transition metal
+oxide physics. The model is multi-band in nature and contains Hund's coupling
+terms, which have pronounced effects on metal-insulator transitions,
+high-temperature superconductivity, and other physical properties. In the
+following, we present a complete theoretical framework for treating the HK
+model using the ground state Auxiliary Field Quantum Monte Carlo (AFQMC) method
+and analyze its performance on few-band models whose parameters approximate
+those observed in ruthenate, rhodates, and other materials exhibiting Hund's
+physics. Unlike previous studies, the constrained path and phaseless
+approximations are used to respectively control the sign and phase problems,
+which enables high accuracy modeling of the HK model's ground state properties
+within parameter regimes of experimental interest. We demonstrate that, after
+careful consideration of the Hubbard-Stratonovich transformations and trial
+wave functions employed, relative errors in the energy of less than 1% can
+routinely be achieved for moderate to large values of the Hund's coupling
+constant. Crucially, our methodology also accurately predicts magnetic ordering
+and phase transitions. The results presented open the door to more predictive
+modeling of Hund's physics within a wide range of strongly-correlated materials
+using AFQMC.",1902.01463v1
+2019-04-03,Spin waves and spin-state transitions in a ruthenate high-temperature antiferromagnet,"Ruthenium compounds play prominent roles in materials research ranging from
+oxide electronics to catalysis, and serve as a platform for fundamental
+concepts such as spin-triplet superconductivity, Kitaev spin-liquids, and
+solid-state analogues of the Higgs mode in particle physics. However, basic
+questions about the electronic structure of ruthenates remain unanswered,
+because several key parameters (including the Hund's-rule, spin-orbit, and
+exchange interactions) are comparable in magnitude, and their interplay is
+poorly understood - partly due to difficulties in synthesizing sizable single
+crystals for spectroscopic experiments. Here we introduce a resonant inelastic
+x-ray scattering (RIXS) technique capable of probing collective modes in
+microcrystals of $4d$-electron materials. We present a comprehensive set of
+data on spin waves and spin-state transitions in the honeycomb antiferromagnet
+SrRu$_{2}$O$_{6}$, which possesses an unusually high N\'eel temperature. The
+new RIXS method provides fresh insight into the unconventional magnetism of
+SrRu$_{2}$O$_{6}$, and enables momentum-resolved spectroscopy of a large class
+of $4d$ transition-metal compounds.",1904.01930v2
+2019-08-07,Chern and $Z_{2}$ topological insulating phases in perovskite-derived $4d$ and $5d$ oxide buckled honeycomb lattices,"Based on density functional theory calculations including a Coulomb repulsion
+parameter $U$, we explore the topological properties of
+(La$X$O$_3$)$_2$/(LaAlO$_3$)$_4$(111) with $X=$ $4d$ and $5d$ cations. The
+metastable ferromagnetic phases of LaTcO$_3$ and LaPtO$_3$ preserve P321
+symmetry and emerge as Chern insulators (CI) with $C$=2 and 1 and band gaps of
+41 and 38 meV at the lateral lattice constant of LaAlO$_3$, respectively. Berry
+curvatures, spin textures as well as edge states provide additional insight
+into the nature of the CI states. While for $X$=Tc the CI phase is further
+stabilized under tensile strain, for $X$=Pd and Pt a site disproportionation
+takes place when increasing the lateral lattice constant from $a_{\rm LAO}$ to
+$a_{\rm LNO}$. The CI phase of $X$=Pt shows a strong dependence on the Hubbard
+$U$ parameter with sign reversal for higher values associated with the change
+of band gap opening mechanism. Parallels to the previously studied
+($X_2$O$_3$)$_1$/(Al$_2$O$_3$)$_5$(0001) honeycomb corundum layers are
+discussed. Additionally, non-magnetic systems with $X$=Mo and W are identified
+as potential candidates for $Z_2$ topological insulators at $a_{\rm LAO}$ with
+band gaps of 26 and 60 meV, respectively. The computed edge states and $Z_{2}$
+invariants underpin the non-trivial topological properties.",1908.02835v1
+2019-08-17,Electronic phase separation at LaAlO3/SrTiO3 interfaces tunable by oxygen deficiency,"Electronic phase separation is crucial for the fascinating macroscopic
+properties of the LaAlO3/SrTiO3 (LAO/STO) paradigm oxide interface, including
+the coexistence of superconductivity and ferromagnetism. We investigate this
+phenomenon using angle-resolved photoelectron spectroscopy (ARPES) in the
+soft-X-ray energy range, where the enhanced probing depth combined with
+resonant photoexcitation allow access to fundamental electronic structure
+characteristics (momentum-resolved spectral function, dispersions and ordering
+of energy bands, Fermi surface) of buried interfaces. Our experiment uses X-ray
+irradiation of the LAO/STO interface to tune its oxygen deficiency, building up
+a dichotomic system where mobile weakly correlated Ti t2g-electrons co-exist
+with localized strongly correlated Ti eg-ones. The ARPES spectra dynamics under
+X-ray irradiation shows a gradual intensity increase under constant Luttinger
+count of the Fermi surface. This fact identifies electronic phase separation
+(EPS) where the mobile electrons accumulate in conducting puddles with fixed
+electronic structure embedded in an insulating host phase, and allows us to
+estimate the lateral fraction of these puddles. We discuss the physics of EPS
+invoking a theoretical picture of oxygen-vacancy clustering, promoted by the
+magnetism of the localized Ti eg-electrons, and repelling of the mobile
+t2g-electrons from these clusters. Our results on the irradiation-tuned EPS
+elucidate the intrinsic one taking place at the stoichiometric LAO/STO
+interfaces.",1908.06321v1
+2019-11-13,Estimation of Cooper pair density and its relation to the critical current density in hole doped high-Tc cuprate superconductors,"Hole concentration in the CuO2 plane largely controls all the properties in
+the normal and superconducting states of high-Tc cuprates. The critical current
+density, Jc, is no exception. Previous hole content dependent studies have
+demonstrated that the role of intrinsic depairing current density in
+determining the observed critical current density in copper oxide
+superconductors. It is also widely agreed upon that the temperature and
+magnetic field dependent vortex pinning energy plays a major role the Jc of a
+system.This pinning energy depends directly on the superconducting condensation
+energy. Superconducting condensation energy, on the other hand, is proportional
+to the Cooper pair density (superpair density), which is found to be highly
+dependent on the hole concentration, p, within the CuO2 plane. We have
+calculated the Cooper pair density, rho_s, of YBCO (Y123), a typical hole doped
+cuprate, as a function of p, in this study. A triangular pseudogap (PG), pinned
+at the Fermi level, in the quasiparticle spectral density has been considered.
+The low-temperature critical current density of a number of Y(Ca)BCO
+superconductors over wide range of compositions and hole concentrations have
+been explored. The normalized values of the superpair density and the critical
+current density exhibit a clear correspondence as the in-plane hole content is
+varied. This systematic behavior provides us with strong evidence that the
+critical current density of hole doped cuprates is primarily dependent on the
+superpair density, which in turn depends on the magnitude of the PG energy.The
+agreement between the estimated p-dependent superpair density and the
+previously experimentally determined superfluid density of Y(Ca)BCO is quite
+remarkable.",1911.05237v1
+2019-11-13,"Anomalous thickness-dependent electrical conductivity in van der Waals layered transition metal halide, Nb_3Cl_8","Understanding the electronic transport properties of layered, van der Waals
+transition metal halides (TMHs) and chalcogenides is a highly active research
+topic today. Of particular interest is the evolution of those properties with
+changing thickness as the 2D limit is approached. Here, we present the
+electrical conductivity of exfoliated single crystals of the TMH, cluster
+magnet, Nb3Cl8, over a wide range of thicknesses both with and without
+hexagonal boron nitride (hBN) encapsulation. The conductivity is found to
+increase by more than three orders of magnitude when the thickness is decreased
+from 280 {\mu}m to 5 nm, at 300 K. At low temperatures and below ~50 nm, the
+conductance becomes thickness independent, implying surface conduction is
+dominating. Temperature dependent conductivity measurements indicate Nb3Cl8 is
+an insulator, however the effective activation energy decreases from a bulk
+value of 310 meV to 140 meV by 5nm. X-ray photoelectron spectroscopy (XPS)
+shows mild surface oxidation in devices without hBN capping, however, no
+significant difference in transport is observed when compared to the capped
+devices, implying the thickness dependent transport behavior is intrinsic to
+the material. A conduction mechanism comprised of a higher conductivity surface
+channel in parallel with a lower conductivity interlayer channel is discussed.",1911.05379v1
+2019-11-18,Thermally Activated Processes for Ferromagnet Intercalation in Graphene-Heavy Metal Interfaces,"The development of graphene (Gr) spintronics requires the ability to engineer
+epitaxial Gr heterostructures with interfaces of high quality, in which the
+intrinsic properties of Gr are modified through proximity with a ferromagnet to
+allow for efficient room temperature spin manipulation or the stabilization of
+new magnetic textures. These heterostructures can be prepared in a controlled
+way by intercalation through graphene of different metals. Using photoelectron
+spectroscopy (XPS) and Scanning Tunneling Microscopy (STM), we achieve a
+nanoscale control of thermal activated intercalation of homogeneous
+ferromagnetic (FM) layer underneath epitaxial Gr grown onto (111)-oriented
+heavy metal (HM) buffers deposited in turn onto insulating oxide surfaces. XPS
+and STM demonstrate that Co atoms evaporated on top of Gr arrange in 3D
+clusters, and, upon thermal annealing, penetrate through and diffuse below Gr
+in a 2D fashion. The complete intercalation of the metal occurs at specific
+temperatures depending on the type of metallic buffer. The activation energy
+and the optimum temperature for the intercalation processes are determined. We
+describe a reliable method to fabricate and characterize in-situ high quality
+Gr-FM/HM heterostructures enabling the realization of novel spin-orbitronic
+devices that exploits the extraordinary properties of Gr.",1911.07549v2
+2019-11-28,Hund-Heisenberg model in superconducting infinite-layer nickelates,"We theoretically investigate the unconventional superconductivity in the
+newly discovered infinite-layer nickelates Nd$_{1-x}$Sr$_{x}$NiO$_{2}$ based on
+a two-band model. By analyzing the transport experiments, we propose that the
+doped holes dominantly enter the Ni $d_{xy}$ or/and $d_{3z^{2}-r^{2}}$ orbitals
+as charged carriers, and form a conducting band. Via the onsite Hund coupling,
+the doped holes are coupled to the Ni localized holes in the $d_{x^{2}-y^{2}}$
+orbital band. We demonstrate that this two-band model could be further reduced
+to a Hund-Heisenberg model. Using the reduced model, we show the non-Fermi
+liquid state above the critical $T_{c}$ could stem from the carriers coupled to
+the spin fluctuations of the localized holes. In the superconducting phase, the
+short-range spin fluctuations mediate the carriers into Cooper pairs and
+establish $d_{x^{2}-y^{2}}$-wave superconductivity. We further predict that the
+doped holes ferromagnetically coupled with the local magnetic moments remain
+itinerant even at very low temperature, and thus the pseudogap hardly emerges
+in nickelates. Our work provides a new superconductivity mechanism for strongly
+correlated multi-orbital systems and paves a distinct way to exploring new
+superconductors in transition or rare-earth metal oxides.",1911.12731v3
+2019-11-28,Magnon damping in the zigzag phase of the Kitaev-Heisenberg-$Γ$ model on a honeycomb lattice,"We calculate magnon dispersions and damping in the Kitaev-Heisenberg model
+with an off-diagonal exchange $\Gamma$ and isotropic third-nearest-neighbor
+interaction $J_3$ on a honeycomb lattice. This model is relevant to a
+description of the magnetic properties of iridium oxides $\alpha$-Li$_2$IrO$_3$
+and Na$_2$IrO$_3$, and Ru-based materials such as $\alpha$-RuCl$_3$. We use an
+unconventional parametrization of the spin-wave expansion, in which each
+Holstein-Primakoff boson is represented by two conjugate hermitian operators.
+This approach gives us an advantage over the conventional one in identifying
+parameter regimes where calculations can be performed analytically. Focusing on
+the parameter regime with the zigzag spin pattern in the ground state that is
+consistent with experiments, we demonstrate that one such region is $\Gamma =
+K>0$, where $K$ is the Kitaev coupling. Within our approach we are able to
+obtain explicit analytical expressions for magnon energies and eigenstates and
+go beyond the standard linear spin-wave theory approximation by calculating
+magnon damping and demonstrating its role in the dynamical structure factor. We
+show that the magnon damping effects in both Born and self-consistent
+approximations are very significant, underscoring the importance of non-linear
+magnon coupling in interpreting broad features in the neutron-scattering
+spectra.",1911.12829v2
+2019-12-19,Unravelling competing microscopic interactions at a phase boundary: a single crystal study of the metastable antiferromagnetic pyrochlore Yb$_{2}$Ge$_{2}$O$_{7}$,"We report inelastic neutron scattering measurements from our newly
+synthesized single crystals of the structurally metastable antiferromagnetic
+pyrochlore Yb$_{2}$Ge$_{2}$O$_{7}$. We determine the four symmetry-allowed
+nearest-neighbor anisotropic exchange parameters via fits to linear spin wave
+theory supplemented by fits of the high-temperature specific heat. The exchange
+parameters so-determined are strongly correlated to the values determined for
+the $g$-tensor components, as previously observed for the related Yb pyrochlore
+Yb$_{2}$Ti$_{2}$O$_{7}$. To address this issue, we directly determined the
+$g$-tensor from electron paramagnetic resonance of 1% Yb-doped
+Lu$_{2}$Ge$_{2}$O$_{7}$, thus enabling an unambiguous determination of the
+exchange parameters. Our results show that Yb$_{2}$Ge$_{2}$O$_{7}$ resides
+extremely close to the classical phase boundary between an antiferromagnetic
+$\Gamma_5$ phase and a splayed ferromagnet phase. By juxtaposing our results
+with recent ones on Yb$_{2}$Ti$_{2}$O$_{7}$, our work illustrates that the Yb
+pyrochlore oxides represent ideal systems for studying quantum magnets in close
+proximity to classical phase boundaries.",1912.09448v2
+2019-12-30,The Fermi surface of PtCoO2 from quantum oscillations and electronic structure calculations,"The delafossite series of layered oxides include some of the highest
+conductivity metals ever discovered. Of these, PtCoO2, with a room temperature
+resistivity of 1.8 microOhmcm for in-plane transport, is the most conducting of
+all. The high conduction takes place in triangular lattice Pt layers, separated
+by layers of Co-O octahedra, and the electronic structure is determined by the
+interplay of the two types of layer. We present a detailed study of quantum
+oscillations in PtCoO2, at temperatures down to 35 mK and magnetic fields up to
+30 T. As for PdCoO2 and PdRhO2, the Fermi surface consists of a single cylinder
+with mainly Pt character, and an effective mass close to the free electron
+value. Due to Fermi-surface warping, two close-lying high frequencies are
+observed. Additionally, a pronounced difference frequency appears. By analysing
+the detailed angular dependence of the quantum-oscillation frequencies, we
+establish the warping parameters of the Fermi surface. We compare these results
+to the predictions of first-principles electronic structure calculations
+including spin-orbit coupling on Pt and Co and on-site correlation U on Co, and
+hence demonstrate that electronic correlations in the Co-O layers play an
+important role in determining characteristic features of the electronic
+structure of PtCoO2.",1912.13071v1
+2020-03-03,Ab Initio Full Cell GW+DMFT for Correlated Materials,"Quantitative prediction of electronic properties in correlated materials
+requires simulations without empirical truncations and parameters. We present a
+method to achieve this goal through a new ab initio formulation of dynamical
+mean-field theory (DMFT). Instead of using small impurities defined in a
+low-energy subspace, which require complicated downfolded interactions which
+are often approximated, we describe a full cell $GW$+DMFT approach, where the
+impurities comprise all atoms in a unit cell or supercell of the crystal. Our
+formulation results in large impurity problems, which we treat here with
+efficient quantum chemistry impurity solvers that work on the real-frequency
+axis, combined with a one-shot $G_0W_0$ treatment of long-range interactions.
+We apply our full cell approach to bulk Si, two antiferromagnetic correlated
+insulators NiO and $\alpha$-Fe$_2$O$_3$, and the paramagnetic correlated metal
+SrMoO$_3$, with impurities containing up to 10 atoms and 124 orbitals. We find
+that spectral properties, magnetic moments, and two-particle spin correlation
+functions are obtained in good agreement with experiments. In addition, in the
+metal oxide insulators, the balanced treatment of correlations involving all
+orbitals in the cell leads to new insights into the orbital character around
+the insulating gap.",2003.01349v2
+2020-03-26,Buried Moire supercells through SrTiO$_3$ nanolayer relaxation,"The interface of complex oxide heterostructures sets the stage for various
+electronic and magnetic phenomena. Many of these collective effects originate
+from the precise structural arrangement at the interface that in turn governs
+local spin- and charge interactions. Currently, interfacial straining, so the
+naturally evolving compressive or tensile strain by mismatch of the neighboring
+lattices, is the most common route towards engineering collective material
+properties -- yet, significant progress might require exploration of entirely
+new approaches towards interface correlations. In this work, we turn the page
+by looking at the interface of a perfectly relaxed, unstrained heterostructure,
+where we identify a highly ordered Moire lattice at an inherently disordered
+SrTiO$_3$ (STO) - LSAT interface. Using high-resolution reciprocal space
+mapping via synchrotron based X-Ray diffraction, we find long-ranged ordered
+supercells of 106/107 unit cells of STO/LSAT, caused by lattice relaxation
+through high-temperature annealing. Model calculations confirm the
+experimentally observed scattering phenomena, showing that cross-interfacial
+bonding is locally different at the Moire-overlap points. Notably, the presence
+of such super-ordered structures in the family of 2D electron gas systems sets
+the ideal conditions for Moire-motif tuned plasmonic responses and
+ferroelectric super-crystallinity and opens up the possibility to novel
+interface functionalities in these simple perovskites.",2003.11762v3
+2020-06-14,Ferroelastic-switching-driven colossal shear strain and piezoelectricity in a hybrid ferroelectric,"Materials that can produce large controllable strains are widely used in
+shape memory devices, actuators and sensors. Great efforts have been made to
+improve the strain outputs of various material systems. Among them,
+ferroelastic transitions underpin giant reversible strains in
+electrically-driven ferro/piezoelectrics and thermally- or magneticallydriven
+shape memory alloys. However, large-strain ferroelastic switching in
+conventional ferroelectrics is very challenging while magnetic and thermal
+controls are not desirable for applications. Here, we demonstrate an
+unprecedentedly large shear strain up to 21.5 % in a hybrid ferroelectric,
+C6H5N(CH3)3CdCl3. The strain response is about two orders of magnitude higher
+than those of top-performing conventional ferroelectric polymers and oxides. It
+is achieved via inorganic bond switching and facilitated by the structural
+confinement of the large organic moieties, which prevents the undesired
+180-degree polarization switching. Furthermore, Br substitution can effectively
+soften the bonds and result in giant shear piezoelectric coefficient (d35 ~
+4800 pm/V) in Br-rich end of the solid solution, C6H5N(CH3)3CdBr3xCl3(1-x). The
+superior electromechanical properties of the compounds promise their potential
+in lightweight and high energy density devices, and the strategy described here
+should inspire the development of next-generation piezoelectrics and
+electroactive materials based on hybrid ferroelectrics.",2006.07883v1
+2020-06-15,Room-temperature quantum spin Hall phase in laser-patterned few-layer 1T'- MoS2,"The quantum-spin-Hall (QSH) phase of 2D topological insulators has attracted
+increased attention since the onset of 2D materials research. While large bulk
+gaps with vanishing edge gaps in atomically thin layers have been reported,
+verifications of the QSH phase by resistance measurements are comparatively
+few. This is partly due to the poor uniformity of the bulk gap induced by the
+substrate over a large sample area and/or defects induced by oxidation. Here,
+we report the observation of the QSH phase at room-temperature in the 1T'-phase
+of few-layer MoS2 patterned onto the 2H semiconducting phase using low-power
+and short-time laser beam irradiation. Two different resistance measurements
+reveal hallmark transport conductance values, ~e2/2h and e2/4h, as predicted by
+the theory. Magnetic-field dependence, scanning tunneling spectra, and
+calculations support the emergence of the room-temperature QSH phase. Although
+further experimental verification is still desirable, our results provide
+feasible application to room-temperature topological devices.",2006.08125v2
+2020-06-23,Antiferromagnetic Half-skyrmions and Bimerons at room temperature,"In the quest for post-CMOS technologies, ferromagnetic skyrmions and their
+anti-particles have shown great promise as topologically protected solitonic
+information carriers in memory-in-logic or neuromorphic devices. However, the
+presence of dipolar fields in ferromagnets, restricting the formation of
+ultra-small topological textures, and the deleterious skyrmion Hall effect when
+driven by spin torques have thus far inhibited their practical implementations.
+Antiferromagnetic analogues, which are predicted to demonstrate relativistic
+dynamics, fast deflection-free motion and size scaling have recently come into
+intense focus, but their experimental realizations in natural antiferromagnetic
+systems are yet to emerge. Here, we demonstrate a family of topological
+antiferromagnetic spin-textures in $\alpha$-Fe$_2$O$_3$ - an earth-abundant
+oxide insulator - capped with a Pt over-layer. By exploiting a first-order
+analogue of the Kibble-Zurek mechanism, we stabilize exotic merons-antimerons
+(half-skyrmions), and bimerons, which can be erased by magnetic fields and
+re-generated by temperature cycling. These structures have characteristic sizes
+of the order ~100 nm that can be chemically controlled via precise tuning of
+the exchange and anisotropy, with pathways to further scaling. Driven by
+current-based spin torques from the heavy-metal over-layer, some of these AFM
+textures could emerge as prime candidates for low-energy antiferromagnetic
+spintronics at room temperature.",2006.12699v2
+2020-08-05,From Mott Insulators to Quantum Metals,"High critical temperature cuprate superconducting materials are composed of
+copper oxide layers and interlayer charge reservoirs. When not doped, these
+cuprates are antiferromagnetic insulators. We propose to design new materials
+by combining alternating layers of parents of hole-doped and electron-doped of
+these cuprates and modifications thereof. Our goal is to find undoped cuprates
+that can be either an antiferromagnetic insulator or a quantum metal. The term
+quantum metal means a metal characterized by long range antiferromagnetic order
+or only strong antiferromagnetic correlations, i.e., it is thus a stable ground
+state against any other perturbations. The new metallic states sought here
+could be precursors to new superconducting states in the absence or presence of
+doping. Using the density functional theory, we report on two compounds
+{La}{Pr}CuO4 and {La}{V}CuO4 that illustrate the different physics described
+above. The curly brackets mean that the preparation of these compounds shall be
+done by depositing a layer containing Pr, then one CuO2 layer, then finally the
+La layer in {La}{Pr}CuO4 for example. The configuration formed by the positions
+of the charge reservoir atoms with respect to the CuO2 layer is an important
+factor in the new procedure we propose here. This paper reports on the X-ray
+diffraction, electronic, optical, and magnetic properties of these hypothetical
+materials. We found that {La}{Pr}CuO4 is a Mott insulator, but {La}{V}CuO4 is
+an undoped correlated quantum metal with long-range order. Our calculations
+were performed using the linearized plane wave method (FP-LAPW) implemented
+within the Wien2k software.",2008.02360v1
+2020-08-27,Odd-frequency pair density wave correlations in underdoped cuprates,"Pair density waves, identified by Cooper pairs with finite center-of-mass
+momentum, have recently been observed in copper oxide based high T$_\textrm{c}$
+superconductors (cuprates). A charge density modulation or wave is also
+ubiquitously found in underdoped cuprates. Within a general mean-field one-band
+model we show that the coexistence of charge density waves and uniform
+superconductivity in $d$-wave superconductors like cuprates, generates an
+odd-frequency spin-singlet pair density wave, in addition to the even-frequency
+counterparts. The strength of the induced odd-frequency pair density wave
+depends on the modulation wave vector of the charge density wave, with the
+odd-frequency pair density waves even becoming comparable to the even-frequency
+ones in parts of the Brillouin zone. We show that a change in the modulation
+wave vector of the charge density wave from bi-axial to uni-axial, can enhance
+the odd-frequency component of the pair density waves. Such a coexistence of
+superconductivity and uni-axial charge density wave has already been
+experimentally verified at high magnetic fields in underdoped cuprates. We
+further discuss the possibility of an odd-frequency spin-triplet pair density
+wave generated in the coexistence regime of superconductivity and spin density
+waves, applicable to the iron-based superconductors. Our work thus presents a
+route to bulk odd-frequency superconductivity in high T$_c$ superconductors.",2008.12021v2
+2020-09-28,A hybrid optoelectronic Mott insulator,"The coupling of electronic degrees of freedom in materials to create
+hybridized functionalities is a holy grail of modern condensed matter physics
+that may produce novel mechanisms of control. Correlated electron systems often
+exhibit coupled degrees of freedom with a high degree of tunability which
+sometimes lead to hybridized functionalities based on external stimuli.
+However, the mechanisms of tunability and the sensitivity to external stimuli
+are determined by intrinsic material properties which are not always
+controllable. A Mott metal-insulator transition, which is technologically
+attractive due to the large changes in resistance, can be tuned by doping,
+strain, electric fields, and orbital occupancy but cannot be, in and of itself,
+controlled externally with light. Here we present a new approach to produce
+hybridized functionalities using a properly engineered
+photoconductor/strongly-correlated hybrid heterostructure, showing control of
+the Metal-to-Insulator transition (MIT) using optical means. This approach
+combines a photoconductor, which does not exhibit an MIT, with a strongly
+correlated oxide, which is not photoconducting. Due to the close proximity
+between the two materials, the heterostructure exhibits large volatile and
+nonvolatile, photoinduced resistivity changes and substantial photoinduced
+shifts in the MIT transition temperatures. This approach can potentially be
+extended to other judiciously chosen combinations of strongly correlated
+materials with systems which exhibit optically, electrically or magnetically
+controllable behavior.",2009.13606v1
+2020-10-13,"High-pressure synthesis of Ba$_2$RhO$_4$, a rhodate analogue of the layered perovskite Sr-ruthenate","A new layered perovskite-type oxide Ba$_2$RhO$_4$ was synthesized by a
+high-pressure technique with the support of convex-hull calculations. The
+crystal and electronic structure were studied by both experimental and
+computational tools. Structural refinements for powder x-ray diffraction data
+showed that Ba$_2$RhO$_4$ crystallizes in a K$_2$NiF$_4$-type structure,
+isostructural to Sr$_2$RuO$_4$ and Ba$_2$IrO$_4$. Magnetic, resistivity, and
+specific heat measurements for polycrystalline samples of Ba$_2$RhO$_4$
+indicate that the system can be characterized as a correlated metal. Despite
+the close similarity to its Sr$_2$RuO$_4$ counterpart in the electronic
+specific heat coefficient and the Wilson ratio, Ba$_2$RhO$_4$ shows no
+signature of superconductivity down to 0.16 K. Whereas the Fermi surface
+topology has reminiscent pieces of Sr$_2$RuO$_4$, an electron-like
+e$_g$-($d_{x^2-y^2}$) band descends below the Fermi level, making of this
+compound unique also as a metallic counterpart of the spin-orbit-coupled Mott
+insulator Ba$_2$IrO$_4$.",2010.06556v1
+2020-10-23,Superconductor-metal quantum transition at the EuO-KTaO3 interface,"Superconductivity has been one of the most fascinating quantum states of
+matter for over several decades. Among the superconducting materials,
+LaAlO3/SrTiO3 interface is of particularly interest since superconductivity
+exists between two insulating materials, which provides it with various unique
+applications compared with bulk superconductors and makes it a suitable
+platform to study the quantum Hall effect, charge density wave,
+superconductivity and magnetism in one device. Therefore, a lot of efforts have
+been made to search new superconducting oxide interface states with higher
+superconducting critical temperature (TC). Recently, a superconducting state
+with TC ~ 2 K has been found at the interface between a ferromagnetic insulator
+EuO and a band insulator (111)-KTaO3. Here, we report the experimental
+investigation of the superconductor-metal quantum phase transition of the
+EuO/KTaO3 interface. Around the transition, a divergence of the dynamical
+critical exponent is observed, which supports the quantum Griffiths singularity
+in the EuO/KTaO3 interface. The quantum Griffiths singularity could be
+attributed to large rare superconducting regions and quenched disorders at the
+interface. Our results could pave the way for studying the exotic
+superconducting properties at the EuO/KTaO3 interface.",2010.12204v2
+2020-11-11,Domain Wall Leaky Integrate-and-Fire Neurons with Shape-Based Configurable Activation Functions,"Complementary metal oxide semiconductor (CMOS) devices display volatile
+characteristics, and are not well suited for analog applications such as
+neuromorphic computing. Spintronic devices, on the other hand, exhibit both
+non-volatile and analog features, which are well-suited to neuromorphic
+computing. Consequently, these novel devices are at the forefront of
+beyond-CMOS artificial intelligence applications. However, a large quantity of
+these artificial neuromorphic devices still require the use of CMOS, which
+decreases the efficiency of the system. To resolve this, we have previously
+proposed a number of artificial neurons and synapses that do not require CMOS
+for operation. Although these devices are a significant improvement over
+previous renditions, their ability to enable neural network learning and
+recognition is limited by their intrinsic activation functions. This work
+proposes modifications to these spintronic neurons that enable configuration of
+the activation functions through control of the shape of a magnetic domain wall
+track. Linear and sigmoidal activation functions are demonstrated in this work,
+which can be extended through a similar approach to enable a wide variety of
+activation functions.",2011.06075v1
+2021-02-19,Surface and interface effects in oxygen deficient SrMnO$_3$ thin films grown on SrTiO$_3$,"Complex oxide functionality, such as ferroelectricity, magnetism or
+superconductivity is often achieved in epitaxial thin-film geometries. Oxygen
+vacancies tend to be the dominant type of defect in these materials but a
+fundamental understanding of their stability and electronic structure has so
+far mostly been established in the bulk or strained bulk, neglecting interfaces
+and surfaces present in a thin-film geometry. We investigate here, via density
+functional theory calculations, oxygen vacancies in the model system of a
+SrMnO$_3$ (SMO) thin film grown on a SrTiO$_3$ (STO) (001) substrate.
+Structural and electronic differences compared to bulk SMO result mainly from
+undercoordination at the film surface. The changed crystal field leads to a
+depletion of subsurface valence-band states and transfer of this charge to
+surface Mn atoms, both of which strongly affect the defect chemistry in the
+film. The result is a strong preference of oxygen vacancies in the surface
+region compared to deeper layers. Finally, for metastable oxygen vacancies in
+the substrate, we predict a spatial separation of the defect from its excess
+charge, the latter being accommodated in the film but close to the substrate
+boundary. These results show that surface and interface effects lead to
+significant differences in stability and electronic structure of oxygen
+vacancies in thin-film geometries compared to the (strained) bulk.",2102.10141v1
+2021-03-30,Positive magnetoresistance and chiral anomaly in exfoliated type-II Weyl semimetal $T_\mathrm{d}$-WTe$_{2}$,"Layered van der Waals semimetallic $T_\mathrm{d}$-WTe$_{2}$, exhibiting
+intriguing properties which include non-saturating extreme positive
+magnetoresistance (MR) and tunable chiral anomaly, has emerged as model
+topological type-II Weyl semimetal system. Here, $\sim$45 nm thick mechanically
+exfoliated flakes of $T_\mathrm{d}$-WTe$_{2}$ are studied $via$ atomic force
+microscopy, Raman spectroscopy, low-$T$/high-$\mu_{0}H$ magnetotransport
+measurements and optical reflectivity. The contribution of anisotropy of the
+Fermi liquid state to the origin of the large positive transverse
+$\mathrm{MR}_\perp$ and the signature of chiral anomaly of the type-II Weyl
+fermions are reported. The samples are found to be stable in air and no
+oxidation or degradation of the electronic properties are observed. A
+transverse $\mathrm{MR}_\perp$ $\sim$1200\,\% and an average carrier mobility
+of $5000$\, cm$^{2}$V$^{-1}$s$^{-1}$ at $T=5\,\mathrm{K}$ for an applied
+perpendicular field $\mu_{0}H_{\perp} = 7\,\mathrm{T}$ are established. The
+system follows a Fermi liquid model for $T\leq50\,\mathrm{K}$ and the
+anisotropy of the Fermi surface is concluded to be at the origin of the
+observed positive MR. The anisotropy of the electronic behaviour is also
+confirmed by optical reflectivity measurements. The relative orientation of the
+crystal axes and of the applied electric and magnetic fields is proven to give
+rise to the observed chiral anomaly in the in-plane magnetotransport.",2103.16326v1
+2021-04-01,Absence of moment fragmentation in the mixed $B$-site pyrochlore Nd$_{2}$GaSbO$_{7}$,"Nd-based pyrochlore oxides of the form Nd$_{2}B_{2}$O$_{7}$ have garnered a
+significant amount of interest owing to the moment fragmentation physics
+observed in Nd$_{2}$Zr$_{2}$O$_{7}$ and speculated in Nd$_{2}$Hf$_{2}$O$_{7}$.
+Notably this phenomenon is not ubiquitous in this family, as it is absent in
+Nd$_{2}$Sn$_{2}$O$_{7}$, which features a smaller ionic radius on the $B$-site.
+Here, we explore the necessary conditions for moment fragmentation in the Nd
+pyrochlore family through a detailed study of the mixed $B$-site pyrochlore
+Nd$_{2}$GaSbO$_{7}$. The $B$-site of this system is characterized by
+significant disorder and an extremely small average ionic radius. Similarly to
+Nd$_{2}$Sn$_{2}$O$_{7}$, we find no evidence for moment fragmentation through
+our bulk characterization and neutron scattering experiments, indicating that
+chemical pressure (and not necessarily the $B$-site disorder) plays a key role
+in the presence or absence of this phenomenon in this material family.
+Surprisingly, the presence of significant $B$-site disorder in
+Nd$_{2}$GaSbO$_{7}$ does not generate a spin glass ground state and instead the
+same all-in-all-out magnetic order identified in other Nd pyrochlores is found
+here.",2104.00791v1
+2021-04-26,Manipulation of polar vortex chirality in oxide superlattices,"Topological polar vortices that are the electric analogues of magnetic
+objects, present great potential in applications of future nanoelectronics due
+to their nanometer size, anomalous dielectric response, and chirality. To
+enable the functionalities, it is prerequisite to manipulate the polar states
+and chirality by using external stimuli. Here, we probe the evolutions of polar
+state and chirality of polar vortices in PbTiO3/SrTiO3 superlattices under
+electric field by using atomically resolved in situ scanning transmission
+electron microscopy and phase-field simulations. We find that the adjacent
+clockwise and counterclockwise vortex usually have opposite chirality. The
+phase-field simulations suggest that the rotation reversal or axial
+polarization switching can lead to the chirality change. Guided by which, we
+experimentally validate that the vortex rotation direction can be changed by
+applying and subsequently removing of electric fields, offering a potential
+strategy to manipulate the vortex chirality. The revealed details of dynamic
+behavior for individual polar vortices at atomic scale and the proposed
+strategy for chirality manipulation provide fundamentals for future device
+applications.",2104.12310v1
+2021-05-05,Ni$_{80}$Fe$_{20}$ Nanotubes with Optimized Spintronic Functionalities Prepared by Atomic Layer Deposition,"Permalloy Ni$_{80}$Fe$_{20}$ is one of the key magnetic materials in the
+field of magnonics. Its potential would be further unveiled if it could be
+deposited in three dimensional (3D) architectures of sizes down to the
+nanometer. Atomic Layer Deposition, ALD, is the technique of choice for
+covering arbitrary shapes with homogeneous thin films. Early successes with
+ferromagnetic materials include nickel and cobalt. Still, challenges in
+depositing ferromagnetic alloys reside in the synthesis via decomposing the
+consituent elements at the same temperature and homogeneously. We report
+plasma-enhanced ALD to prepare permalloy Ni$_{80}$Fe$_{20}$ thin films and
+nanotubes using nickelocene and iron(III) tert-butoxide as metal precursors,
+water as the oxidant agent and an in-cycle plasma enhanced reduction step with
+hydrogen. We have optimized the ALD cycle in terms of Ni:Fe atomic ratio and
+functional properties. We obtained a Gilbert damping of 0.013, a resistivity of
+28 $\mu\Omega$cm and an anisotropic magnetoresistance effect of 5.6 $\%$ in the
+planar thin film geometry. We demonstrate that the process also works for
+covering GaAs nanowires, resulting in permalloy nanotubes with high aspect
+ratios and diameters of about 150 nm. Individual nanotubes were investigated in
+terms of crystal phase, composition and spin-dynamic response by microfocused
+Brillouin Light Scattering. Our results enable NiFe-based 3D spintronics and
+magnonic devices in curved and complex topology operated in the GHz frequency
+regime.",2105.01969v1
+2021-05-08,Evidence for strong electron correlations in a non-symmorphic Dirac semimetal,"Metallic iridium oxides (iridates) provide a fertile playground to explore
+new phenomena resulting from the interplay between topological protection,
+spin-orbit and electron-electron interactions. To date, however, few studies of
+the low energy electronic excitations exist due to the difficulty in
+synthesising crystals with sufficiently large carrier mean-free-paths. Here, we
+report the observation of Shubnikov-de Haas quantum oscillations in
+high-quality single crystals of monoclinic SrIrO$_3$ in magnetic fields up to
+35~T. Analysis of the oscillations reveals a Fermi surface comprising multiple
+small pockets with effective masses up to 4.5 times larger than the calculated
+band mass. \textit{Ab-initio} calculations reveal robust linear band-crossings
+at the Brillouin zone boundary, due to its non-symmorphic symmetry, and overall
+we find good agreement between the angular dependence of the oscillations and
+the theoretical expectations. Further evidence of strong electron correlations
+is realized through the observation of signatures of non-Fermi liquid transport
+as well as a large Kadowaki-Woods ratio. These collective findings, coupled
+with knowledge of the evolution of the electronic state across the
+Ruddlesden-Popper iridate series, establishes monoclinic SrIrO$_3$ as a
+topological semimetal on the boundary of the Mott metal-insulator transition.",2105.03740v2
+2021-05-19,"Polyrotaxane: New Generation of Sustainable, Ultra-flexible, Form-stable and Smart Phase Change Materials","The development of thermal energy storage materials is the most attractive
+strategy to harvest the solar energy and increase the energy utilization
+efficiency. Phase change materials (PCMs) have received much attention in this
+research field for several decades. Herein, we reported a new kind of PCM micro
+topological structure, design direction, and the ultra-flexible, form-stable
+and smart PCMs, polyrotaxane. The structure of polyrotaxane was fully confirmed
+by 1H nuclear magnetic resonance,attenuated total reflection-fourier transform
+infrared and X-ray diffraction. Then the tensile properties,thermal stability
+in the air, phase change energy storage and shape memory properties of the
+films were systematically analyzed. The results showed that all the mechanical
+performance, thermal stability in air and shape memory properties of
+polyrotaxanes were enhanced significantly compared to those of polyethylene
+oxide (PEO). The form stability at temperatures above the melting point of PEO
+significantly increased with the {\alpha}-CD addition. Further with the high
+phase transition enthalpy and excellent cycle performance, the polyrotaxane
+films are therefore promising sustainable and advanced form-stable phase change
+materials for thermal energy storage. Notably, its ultra-high flexibility,
+remolding ability and excellent shape memory properties provide a convenient
+way for the intelligent heat treatment packaging of complex and flexible
+electronic devices. In addition, this is a totally novel insight for
+polyrotaxane application and new design method for form-stable PCMs.",2105.09074v1
+2021-05-27,"Nickelate superconductivity without rare-earth magnetism: (La,Sr)NiO$_{2}$","The observation of superconductivity in infinite layer nickelate
+(Nd,Sr)NiO$_{2}$ thin films has led to rapid theoretical and experimental
+investigations of these copper-oxide-analogue systems [1-15]. Superconductivity
+has also been found in (Pr,Sr)NiO$_{2}$ [16,17], but not previously in
+(La,Sr)NiO$_{2}$ [2], raising a fundamental question whether superconductivity
+is associated with the presence of rare-earth moments [18,19]. Here we show
+that with significant materials optimization, substantial portions of the
+La$_{1-x}$Sr$_{x}$NiO$_{2}$ phase diagram can enter the regime of coherent
+low-temperature transport ($x$ = 0.14 - 0.20), with subsequent superconducting
+transitions and a maximum onset of ~ 9 K at $x$ = 0.20. Additionally, we
+observe the unexpected indication of a superconducting ground state in undoped
+LaNiO$_{2}$, which likely reflects the self-doped nature of the electronic
+structure. Combining the results of (La/Pr/Nd)$_{1-x}$Sr$_{x}$NiO$_{2}$ reveals
+a generalized superconducting dome, characterized by systematic shifts in the
+unit cell volume and in the relative electron-hole populations across the
+lanthanides.",2105.13494v1
+2021-06-07,The ground state in a proximity to a possible Kitaev spin liquid: An undistorted honeycomb iridate NaxIrO3 (0.60 < x < 0.80),"We report results of our study of a newly synthesized honeycomb iridate
+NaxIrO3 (0.60 < x < 0.80). Single-crystal NaxIrO3 adopts a honeycomb lattice
+noticeably without distortions and stacking disorder inherently existent in its
+sister compound Na2IrO3. The oxidation state of the Ir ion is a mixed valence
+state resulting from a majority Ir5+(5d4) ion and a minority Ir6+(5d3) ion.
+NaxIrO3 is a Mott insulator likely with a predominant pseudospin = 1 state. It
+exhibits an effective moment of 1.1 Bohr Magneton/Ir and a Curie-Weiss
+temperature of -19 K but with no discernable long-range order above 1 K. The
+physical behavior below 1 K features two prominent anomalies at Th = 0.9 K and
+Tl = 0.12 K in both the heat capacity and AC magnetic susceptibility.
+Intermediate between Th and Tl lies a pronounced temperature linearity of the
+heat capacity with a large slope of 77 mJ/mole K2, a feature expected for
+highly correlated metals but not at all for insulators. These results along
+with comparison drawn with the honeycomb lattices Na2IrO3 and (Na0.2Li0.8)2IrO3
+point to an exotic ground state in a proximity to a possible Kitaev spin
+liquid.",2106.04012v1
+2021-07-15,Epitaxial stabilization of metastable 3C BaRuO3 thin film with ferromagnetic non-Fermi liquid phase,"Thin films of perovskite Ruthenates of the general formula ARuO3 (A = Ca and
+Sr) are versatile electrical conductors for viable oxide electronics. They are
+also scientifically intriguing, as they exhibit non-trivial electromagnetic
+ground states depending on the A-site element. Among them, realization of the
+cubic perovskite (3C) BaRuO3 thin film has been a challenge so far, because the
+3C phase is metastable with the largest formation energy among the various
+polymorph phases of BaRuO3. In this study, we successfully prepared 3C BaRuO3
+thin films employing epitaxial stabilization. The 3C BaRuO3 thin films show
+itinerant ferromagnetism with a transition temperature of ~48 K and a non-Fermi
+liquid phase. The epitaxial stabilization of the 3C BaRuO3 further enabled us
+to make a standard comparison of perovskite Ruthenates thin films, thereby
+establishing the importance of the Ru-O orbital hybridization in understanding
+the itinerant magnetic system.",2107.07181v1
+2021-07-16,Long-Range Superconducting Proximity Effect in Nickel Nanowires,"When a ferromagnet is placed in contact with a superconductor, owing to
+incompatible spin order, the Cooper pairs from the superconductor cannot
+survive more than one or two nanometers inside the ferromagnet. This is
+confirmed in the measurements of ferromagnetic nickel (Ni) nanowires contacted
+by superconducting niobium (Nb) leads. However, when a 3 nm thick copper oxide
+(CuO) buffer layer made by exposing an evaporated or a sputtered 3 nm Cu film
+to air, is inserted between the Nb electrodes and the Ni wire, the spatial
+extent of the superconducting proximity range is dramatically increased from 2
+to a few tens of nanometers. Scanning transmission electron microscope study
+confirms the formation of a 3 nm thick CuO layer when an evaporated Cu film is
+exposed to air. Magnetization measurements of such a 3 nm CuO film on a SiO2/Si
+substrate and on Nb/SiO2/Si show clear evidence of ferromagnetism. One way to
+understand the long-range proximity effect in the Ni nanowire is that the CuO
+buffer layer with ferromagnetism facilitates the conversion of singlet
+superconductivity in Nb into triplet supercurrent along the Ni nanowires.",2107.08018v3
+2021-07-26,Electrically Enhanced Exchange Bias via Solid State Magneto-Ionics,"Electrically induced ionic motion offers a new way to realize
+voltage-controlled magnetism, opening the door to a new generation of logic,
+sensor, and data storage technologies. Here, we demonstrate an effective
+approach to magneto-ionically and electrically tune exchange bias in
+Gd/Ni$_{1-x}$Co$_{x}$O thin films (x=0.50, 0.67), where neither of the layers
+alone is ferromagnetic at room temperature. The Gd capping layer deposited onto
+antiferromagnetic Ni$_{1-x}$Co$_{x}$O initiates a solid-state redox reaction
+that reduces an interfacial region of the oxide to ferromagnetic NiCo. Exchange
+bias is established after field cooling, which can be enhanced by up to 35%
+after a voltage conditioning and subsequently reset with a second field
+cooling. These effects are caused by the presence of an interfacial
+ferromagnetic NiCo layer, which further alloys with the Gd layer upon field
+cooling and voltage application, as confirmed by electron microscopy and
+polarized neutron reflectometry studies. These results highlight the viability
+of the solid-state magneto-ionic approach to achieve electric control of
+exchange bias, with potentials for energy-efficient magneto-ionic devices.",2107.12503v2
+2021-07-28,Dynamics of Polar Skyrmion Bubbles under Electric Fields,"Room-temperature polar skyrmion bubbles that are recently found in oxide
+superlattice, have received enormous interests for their potential applications
+in nanoelectronics due to the nanometer size, emergent chirality, and negative
+capacitance. For practical applications, the ability to controllably manipulate
+them by using external stimuli is prerequisite. Here, we study the dynamics of
+individual polar skyrmion bubbles at the nanoscale by using in situ biasing in
+a scanning transmission electron microscope. The reversible electric
+field-driven phase transition between topological and trivial polar states are
+demonstrated. We create, erase and monitor the shrinkage and expansion of
+individual polar skyrmions. We find that their transition behaviors are
+substantially different from that of magnetic analogue. The underlying
+mechanism is discussed by combing with the phase-field simulations. The
+controllable manipulation of nanoscale polar skyrmions allows us to tune the
+dielectric permittivity at atomic scale and detailed knowledge of their phase
+transition behaviors provides fundamentals for their applications in
+nanoelectronics.",2107.13390v1
+2021-08-08,On the Electron Pairing Mechanism of Copper-Oxide High Temperature Superconductivity,"The elementary CuO2 plane sustaining cuprate high-temperature
+superconductivity occurs typically at the base of a periodic array of
+edge-sharing CuO5 pyramids. Virtual transitions of electrons between adjacent
+planar Cu and O atoms, occurring at a rate $t/{\hbar}$ and across the
+charge-transfer energy gap E, generate 'superexchange' spin-spin interactions
+of energy $J\approx4t^4/E^3$ in an antiferromagnetic correlated-insulator
+state. However, Hole doping the CuO2 plane converts this into a very high
+temperature superconducting state whose electron-pairing is exceptional. A
+leading proposal for the mechanism of this intense electron-pairing is that,
+while hole doping destroys magnetic order it preserves pair-forming
+superexchange interactions governed by the charge-transfer energy scale E. To
+explore this hypothesis directly at atomic-scale, we combine single-electron
+and electron-pair (Josephson) scanning tunneling microscopy to visualize the
+interplay of E and the electron-pair density nP in ${Bi_2Sr_2CaCu_2O_{8+x}}$.
+The responses of both E and nP to alterations in the distance {\delta} between
+planar Cu and apical O atoms are then determined. These data reveal the
+empirical crux of strongly correlated superconductivity in CuO2, the response
+of the electron-pair condensate to varying the charge transfer energy.
+Concurrence of predictions from strong-correlation theory for hole-doped
+charge-transfer insulators with these observations, indicates that
+charge-transfer superexchange is the electron-pairing mechanism of
+superconductive ${Bi_2Sr_2CaCu_2O_{8+x}}$.",2108.03655v3
+2021-09-05,Isostructural Metal-Insulator Transition Driven by Dimensional-Crossover in SrIrO3 Heterostructures,"Dimensionality reduction induced metal-insulator transitions in oxide
+heterostructures are usually coupled with structural and magnetic phase
+transitions, which complicate the interpretation of the underlying physics.
+Therefore, achieving isostructural MIT is of great importance for fundamental
+physics and even more for applications. Here, we report an isostructural
+metal-insulator transition driven by dimensional-crossover in spin-orbital
+coupled SrIrO3 films. By using in-situ pulsed laser deposition and
+angle-resolved photoemission spectroscopy, we synthesized and investigated the
+electronic structure of SrIrO3 ultrathin films with atomic-layer precision.
+Through inserting orthorhombic CaTiO3 buffer layers, we demonstrate that the
+crystal structure of SrIrO3 films remains bulk-like with similar oxygen
+octahedra rotation and tilting when approaching the ultrathin limit. We observe
+that a dimensional-crossover metal-insulator transition occurs in isostructural
+SrIrO3 films. Intriguingly, we find the bandwidth of Jeff=3/2 states reduces
+with lowering the dimensionality and drives the metal-insulator transition. Our
+results establish a bandwidth controlled metal-insulator transition in the
+isostructural SrIrO3 thin films.",2109.02056v1
+2021-09-27,Ultrafast renormalization of the onsite Coulomb repulsion in a cuprate superconductor,"Ultrafast lasers are an increasingly important tool to control and stabilize
+emergent phases in quantum materials. Among a variety of possible excitation
+protocols, a particularly intriguing route is the direct light-engineering of
+microscopic electronic parameters, such as the electron hopping and the local
+Coulomb repulsion (Hubbard $U$). In this work, we use time-resolved x-ray
+absorption spectroscopy to demonstrate the light-induced renormalization of the
+Hubbard $U$ in a cuprate superconductor, La$_{1.905}$Ba$_{0.095}$CuO$_4$. We
+show that intense femtosecond laser pulses induce a substantial redshift of the
+upper Hubbard band, while leaving the Zhang-Rice singlet energy unaffected. By
+comparing the experimental data to time-dependent spectra of single- and
+three-band Hubbard models, we assign this effect to a $\sim140$ meV reduction
+of the onsite Coulomb repulsion on the copper sites. Our demonstration of a
+dynamical Hubbard $U$ renormalization in a copper oxide paves the way to a
+novel strategy for the manipulation of superconductivity, magnetism, as well as
+to the realization of other long-range-ordered phases in light-driven quantum
+materials.",2109.13229v1
+2021-10-12,Bridging the Band Gap: What Device Physicists Need to Know About Machine Learning,"This article surveys the landscape of semiconductor materials and devices
+research for the acceleration of machine learning (ML) algorithms. We observe a
+disconnect between the semiconductor and device physics and engineering
+communities, and the digital logic and computer hardware architecture
+communities. The article first provides an overview of the principles of
+computational complexity and fundamental physical limits to computing and their
+relation to physical systems. The article then provides an introduction to ML
+by presenting three key components of ML systems: representation, evaluation,
+and optimisation. The article then discusses and provides examples of the
+application of emerging technologies from the demiconductor and device physics
+domains as solutions to computational problems, alongside a brief overview of
+emerging devices for computing applications. The article then reviews the
+landscape of ML accelerators, comparing fixed-function and reprogrammable
+digital logic with novel devices such as memristors, resistive memories,
+magnetic memories, and probabilistic bits. We observe broadly lower performance
+of ML accelerators based on novel devices and materials when compared to those
+based on digital complimentary metal-oxide semiconductor (CMOS) technology,
+particularly in the MNIST optical character recognition task, a common ML
+benchmark, and also highlight the lack of a trend of progress in approaches
+based on novel materials and devices. Lastly, the article proposes figures of
+merit for meaningful evaluation and comparison of different ML implementations
+in the hope of fostering a dialogue between the materials science, device
+physics, digital logic, and computer architecture communities by providing a
+common frame of reference for their work.",2110.05910v2
+2021-11-25,NV microscopy of thermally controlled stresses caused by Cr$_2$O$_3$ thin films,"Many modern applications, including quantum computing and quantum sensing,
+use substrate-film interfaces. Particularly, thin films of chromium or titanium
+and their oxides are commonly used to bind various structures, such as
+resonators, masks, or microwave antennas, to a diamond surface. Due to
+different thermal expansions of involved materials, such films and structures
+could produce significant stresses, which need to be measured or predicted. In
+this paper, we demonstrate imaging of stresses in the top layer of diamond with
+deposited structures of Cr$_2$O$_3$ at temperatures 19$^{\circ}$C and
+37$^{\circ}$C by using stress-sensitive optically detected magnetic resonances
+(ODMR) in NV centers. We also calculated stresses in the diamond-film interface
+by using finite-element analysis and correlated them to measured ODMR frequency
+shifts. As predicted by the simulation, the measured high-contrast
+frequency-shift patterns are only due to thermal stresses, whose spin-stress
+coupling constant along the NV axis is 21$\pm$1 MHz/GPa, that is in agreement
+with constants previously obtained from single NV centers in diamond
+cantilever. We demonstrate that NV microscopy is a convenient platform for
+optically detecting and quantifying spatial distributions of stresses in
+diamond-based photonic devices with micrometer precision and propose thin films
+as a means for local application of temperature-controlled stresses. Our
+results also show that thin film structures produce significant stresses in
+diamond substrates, which should be accounted for in NV-based applications.",2111.12979v2
+2021-12-06,Interior Structure Models Of Venus,"Venus' mass and radius are similar to those of Earth. However,
+dissimilarities in atmospheric properties, geophysical activity and magnetic
+field generation could hint towards significant differences in the chemical
+composition and interior evolution of the two planets. Although various
+explanations for the differences between Venus and Earth have been proposed,
+the currently available data are insufficient to discriminate among the
+different solutions. Here we investigate the possible range of Venus structure
+models. We assume that core segregation happened as a single-stage event. The
+mantle composition is inferred from the core composition using a prescription
+for metal-silicate partitioning. We consider three different cases for the
+composition of Venus defined via the bulk Si and Mg content, and the core's S
+content. Permissible ranges for the core size, mantle and core composition as
+well as the normalized moment of inertia (MoI) are presented for these
+compositions. A solid inner core could exist for all compositions. We estimate
+that Venus' MoI is 0.317-0.351 and its core size 2930-4350 km for all assumed
+compositions. Higher MoI values correspond to more oxidizing conditions during
+core segregation. A determination of the abundance of FeO in Venus' mantle by
+future missions could further constrain its composition and internal structure.
+This can reveal important information on Venus' formation and evolution, and
+possibly, the reasons for the differences between Venus and our home planet.",2112.03225v2
+2021-12-31,Ferromagnetic Enhancement in LaMnO3 Films with Release and Flexure,"A variety of novel phenomena and functionalities emerge from lowering the
+dimensionality of materials and enriching the degrees of freedom in modulation.
+In this work, it is found that the saturation magnetization of LaMnO3 (LMO)
+films is largely enhanced by 56% after releasing from a brand-new phase of
+tetragonal strontium aluminate buffer layer, and is significantly increased by
+92% with bending films to a curvature of 1 mm-1 using a water-assisted
+direct-transferring method. Meanwhile, the Curie temperature of LMO films has
+been improved by 13 K. High-resolution spherical aberration-corrected scanning
+transmission electron microscopy and first-principles calculations
+unambiguously demonstrate that the enhanced ferromagnetism is attributed to the
+strengthened Mn-O-Mn super-exchange interactions from the augmented
+characteristics of the unconventional P21/n structure caused by the
+out-of-plane lattice shrinking after strain releasing and increased flexure
+degree of freestanding LMO films. This work paves a way to achieve large-scale
+and crack-and-wrinkle-free freestanding films of oxides with largely improved
+functionalities.",2112.15307v1
+2022-01-21,A single hole spin with enhanced coherence in natural silicon,"Semiconductor spin qubits based on spin-orbit states are responsive to
+electric field excitation allowing for practical, fast and potentially scalable
+qubit control. Spin-electric susceptibility, however, renders these qubits
+generally vulnerable to electrical noise, which limits their coherence time.
+Here we report on a spin-orbit qubit consisting of a single hole
+electrostatically confined in a natural silicon metal-oxide-semiconductor
+device. By varying the magnetic field orientation, we reveal the existence of
+operation sweet spots where the impact of charge noise is minimized while
+preserving an efficient electric-dipole spin control. We correspondingly
+observe an extension of the Hahn-echo coherence time up to 88 $\mu$s, exceeding
+by an order of magnitude the best reported values for hole-spin qubits, and
+approaching the state-of-the-art for electron spin qubits with synthetic
+spin-orbit coupling in isotopically-purified silicon. This finding largely
+enhances the prospects of silicon-based hole spin qubits for scalable quantum
+information processing.",2201.08637v2
+2022-02-01,Proximity-Induced Superconductivity in Atomically Precise Nanographene,"Obtaining a robust superconducting state in atomically precise nanographene
+(NG) structures by proximity to a superconductor could foster the discovery of
+topological superconductivity in graphene. On-surface synthesis of such NGs has
+been achieved on noble metals or metal oxides, however, it is still absent on
+superconductors. Here, we present a synthetic method to induce
+superconductivity to polymeric chains and NGs adsorbed on the superconducting
+Nb(110) substrate covered by thin Ag films. Using atomic force microscopy at
+low-temperature, we characterize the chemical structure of each sub-product
+formed on the superconducting Ag layer. Scanning tunneling spectroscopy further
+allows us to elucidate electronic properties of these nanostructures, which
+consistently show a superconducting gap. We foresee our approach to become a
+promising platform for exploring the interplay between carbon magnetism and
+superconductivity at the fundamental level.",2202.00460v1
+2022-02-09,An electrically-driven single-atom `flip-flop' qubit,"The spins of atoms and atom-like systems are among the most coherent objects
+in which to store quantum information. However, the need to address them using
+oscillating magnetic fields hinders their integration with quantum electronic
+devices. Here we circumvent this hurdle by operating a single-atom `flip-flop'
+qubit in silicon, where quantum information is encoded in the electron-nuclear
+states of a phosphorus donor. The qubit is controlled using local electric
+fields at microwave frequencies, produced within a metal-oxide-semiconductor
+device. The electrical drive is mediated by the modulation of the
+electron-nuclear hyperfine coupling, a method that can be extended to many
+other atomic and molecular systems. These results pave the way to the
+construction of solid-state quantum processors where dense arrays of atoms can
+be controlled using only local electric fields.",2202.04438v3
+2022-03-15,Formation of CuO$_2$ sublattices by suppression of interlattice correlations in tetragonal CuO,"We investigate the tetragonal phase of the binary transition metal oxide CuO
+(t-CuO) within the context of cellular dynamical mean-field theory. Due to its
+strong antiferromagnetic correlations and simple structure, analysing the
+physics of t-CuO is of high interest as it may pave the way towards a more
+complete understanding of high temperature superconductivity in hole-doped
+antiferromagnets. In this work we give a formal justification for the weak
+coupling assumption that has previously been made for the interconnected
+sublattices within a single layer of t-CuO by studying the non-local
+self-energies of the system. We compute momentum-resolved spectral functions
+using a Matrix Product State (MPS)-based impurity solver directly on the real
+axis, which does not require any numerically ill-conditioned analytic
+continuation. The agreement with photoemission spectroscopy indicates that a
+single band Hubbard model is sufficient to capture the material's low energy
+physics. We perform calculations on a range of different temperatures, finding
+two magnetic regimes, for which we identify the driving mechanism behind their
+respective insulating state. Finally, we show that in the hole-doped regime the
+sublattice structure of t-CuO has interesting consequences on the symmetry of
+the superconducting state.",2203.07880v2
+2022-03-29,Accurate electronic properties and intercalation voltages of olivine-type Li-ion cathode materials from extended Hubbard functionals,"The design of novel cathode materials for Li-ion batteries would greatly
+benefit from accurate first-principles predictions of structural, electronic,
+and magnetic properties as well as intercalation voltages in compounds
+containing transition-metal elements. For such systems, density-functional
+theory (DFT) with standard (semi-)local exchange-correlation functionals is of
+limited use as it often fails due to strong self-interaction errors that are
+especially relevant in the partially filled $d$ shells. Here, we perform a
+detailed comparative study of the phospho-olivine cathode materials
+Li$_x$MnPO$_4$, Li$_x$FePO$_4$, and the mixed transition metal
+Li$_x$Mn$_{1/2}$Fe$_{1/2}$PO$_4$ ($x=0, 1/4, 1/2, 3/4, 1$) using four
+electronic-structure methods: DFT, DFT+$U$, DFT+$U$+$V$, and HSE06. We show
+that DFT+$U$+$V$, with onsite $U$ and intersite $V$ Hubbard parameters
+determined from first principles and self-consistently with respect to the
+structural parameters by means of density-functional perturbation theory
+(linear response), provides the most accurate description of the electronic
+structure of these challenging compounds. In particular, we demonstrate that
+DFT+$U$+$V$ displays very clearly ""digital"" changes in oxidation states of the
+transition-metal ions in all compounds, including the mixed-valence phases
+occurring at intermediate Li concentrations, leading to voltages in remarkable
+agreement with experiments. We show that the inclusion of intersite Hubbard
+interactions is essential for the accurate prediction of thermodynamic
+quantities, balancing the drive for localization induced by the onsite $U$ with
+intersite $V$ orbital hybridizations.",2203.15732v2
+2022-04-29,Anomalous Josephson Coupling and High-Harmonics in Non-Centrosymmetric Superconductors with $S$-wave Spin-Triplet Pairing,"We study the Josephson effects arising in junctions made of
+non-centrosymmetric superconductors with spin-triplet pairing having $s$-wave
+orbital-singlet symmetry. We demonstrate that the orbital dependent character
+of the spin-triplet order parameter determines its non-trivial texture in the
+momentum space due to the inversion symmetry breaking and spin-orbit
+interactions. The emergence of this pattern is responsible for the occurrence
+of an anomalous Josephson coupling and a dominance of high-harmonics in the
+current phase relation. Remarkably, due to the spin-orbital couplings,
+variations in the electronic structure across the heterostructure can generally
+turn the ground state of the junction from 0- to a generic value of the
+Josephson phase, thus realizing the so-called $\varphi$-junction. Hallmarks of
+the resulting Josephson behavior, apart from non-standard current-phase
+relation, are provided by an unconventional temperature and magnetic field
+dependence of the critical current. These findings indicate the path for the
+design of superconducting orbitronics devices and account for several observed
+anomalies of the supercurrent in oxide interface superconductors.",2204.14083v2
+2022-05-06,Anisotropic carrier dynamics in a laser-excited Fe$_{1}$/(MgO)$_{3}$(001) heterostructure from real-time time-dependent DFT,"The interaction of a femtosecond optical pulse with a
+Fe$_{1}$/(MgO)$_{3}$(001) metal/oxide heterostructure is investigated using
+time-dependent density functional theory (TDDFT) calculations in the real-time
+domain. We systematically study electronic excitations as a function of laser
+frequency, peak power density and polarization direction. While spin-orbit
+coupling is found to result in only a small time-dependent reduction of
+magnetization (less than 10%), we find a marked anisotropy in the response to
+in-plane and out-of-plane polarized light, which changes its character
+qualitatively depending on the excitation energy: the Fe-layer is efficiently
+addressed at low frequencies by in-plane polarized light, whereas for
+frequencies higher than the MgO band gap, we find a particularly strong
+response of the central MgO-layer for cross-plane polarized light. For laser
+excitations between the charge transfer gap and the MgO band gap, the interface
+plays the most important role, as it mediates concerted transitions from the
+valence band of MgO into the $3d$ states of Fe closely above the Fermi level
+and from the Fe-states below the Fermi level into the conduction band of MgO.
+As these transitions can occur simultaneously altering charge balance of the
+layers, they could potentially lead to an efficient transfer of excited
+carriers into the MgO bulk, where the corresponding electron and hole states
+can be separated by an energy which is significantly larger than the photon
+energy.",2205.03178v1
+2022-08-14,Chern insulators and high Curie temperature Dirac half-metal in two-dimensional metal-organic frameworks,"Two-dimensional (2D) magnetic materials with nontrivial topological states
+have drawn considerable attention recently. Among them, 2D metal-organic
+frameworks (MOFs) are standing out due to their advantages, such as the easy
+synthesis in practice and less sensitivity to oxidation that are distinctly
+different from inorganic materials. By means of density-functional theory
+calculations, we systematically investigate the electronic and topological
+properties of a class of 2D MOFs X(C21H15N3) (X = transition metal element from
+3d to 5d). Excitingly, we find that X(C21H15N3) (X = Ti, Zr, Ag, Au) are Chern
+insulators with sizable band gaps (~7.1 meV). By studying a four-band effective
+model, it is revealed that the Chern insulator phase in X(C21H15N3) (X = Ti,
+Zr, Ag, Au) is caused cooperatively by the band inversion of the p orbitals of
+the C21H15N3 molecule and the intrinsic ferromagnetism of X(C21H15N3).
+Additionally, Mn(C21H15N3) is a Dirac half-metal ferromagnet with a high Curie
+temperature up to 156 K. Our work demonstrates that 2D MOFs X(C21H15N3) are
+good platforms for realizing Quantum anomalous Hall effect and designing novel
+spintronic devices based on half-metals with high-speed and long-distance spin
+transport.",2208.06891v2
+2022-09-01,Reflective Dielectric Cavity Enhanced Emission from Hexagonal Boron Nitride Spin Defect Arrays,"Among the various kinds of spin defects in hBN, the negatively charged boron
+vacancy ($\rm V_B^-$) spin defect that can be deterministically generated is
+undoubtedly a potential candidate for quantum sensing, but its low quantum
+efficiency restricts its %use in practical applications. Here, we demonstrate a
+robust enhancement structure with advantages including easy on-chip
+integration, convenient processing, low cost and suitable broad-spectrum
+enhancement for $\rm V_B^-$ defects. %Improved photoluminescence (PL) intensity
+and optically detected magnetic resonance (ODMR) contrast of $\rm V_B^-$ defect
+arrays. In the experiment, we used a metal reflective layer under the hBN
+flakes, filled with a transition dielectric layer in the middle, and adjusted
+the thickness of the dielectric layer to achieve the best coupling between the
+reflective dielectric cavity and the hBN spin defect. Using a reflective
+dielectric cavity, we achieved a PL enhancement of approximately 7-fold, and
+the corresponding ODMR contrast achieved 18\%. Additionally, the oxide layer of
+the reflective dielectric cavity can be used as an integrated material for
+micro-nano photonic devices for secondary processing, which means that it can
+be combined with other enhancement structures to achieve stronger enhancement.
+This work has guiding significance for realizing the on-chip integration of
+spin defects in two-dimensional materials.",2209.00256v1
+2022-09-07,Ab initio Quantum Simulation of Strongly Correlated Materials with Quantum Embedding,"Quantum computing has shown great potential in various quantum chemical
+applications such as drug discovery, material design, and catalyst
+optimization. Although significant progress has been made in quantum simulation
+of simple molecules, ab initio simulation of solid-state materials on quantum
+computers is still in its early stage, mostly owing to the fact that the system
+size quickly becomes prohibitively large when approaching the thermodynamic
+limit. In this work, we introduce an orbital-based multi-fragment approach on
+top of the periodic density matrix embedding theory, resulting in a
+significantly smaller problem size for the current near-term quantum computer.
+We demonstrate the accuracy and efficiency of our method compared with the
+conventional methodologies and experiments on solid-state systems with complex
+electronic structures. These include spin polarized states of a hydrogen chain
+(1D-H), the equation of states of a boron nitride layer (h-BN) as well as the
+magnetic ordering in nickel oxide (NiO), a prototypical strongly correlated
+solid. Our results suggest that quantum embedding combined with a chemically
+intuitive fragmentation can greatly advance quantum simulation of realistic
+materials, thereby paving the way for solving important yet classically hard
+industrial problems on near-term quantum devices.",2209.03202v2
+2023-01-11,Coexistence of zigzag antiferromagnetic order and superconductivity in compressed NiPSe3,"NiPSe3 is regarded as a bandwidth-controlled Mott insulator, distinct from
+the widely studied Mott insulating magnetic graphene MPSe3 (M = Mn and Fe)
+family. By employing high-pressure synchrotron X-ray diffraction, we observe
+two structural transitions as a function of pressure. With the help of
+first-principles calculations, we discover the antiferromagnetic (AFM) moment
+directions of NiPSe3 switch from out-of-plane to in-plane and the honeycomb
+layers slide relative to each other at the first structural transition. The
+in-plane AFM order persists until the second structural transition, whereupon
+the two-dimensional (2D) structure assumes a more three-dimensional (3D)
+character. A bandwidth-controlled Mott insulator-metal transition (IMT) occurs
+between the two structural transitions at 8.0 GPa, concomitant with the
+emergence of superconductivity with 4.8 K. The superconductivity in NiPSe3
+emerging in the 2D monoclinic phase coexists with the in-plane AFM order and
+continues into the 3D trigonal phase. Our electronic structure calculations
+reveal that the Mott IMT and superconductivity in NiPSe3 are both closely
+related to the enhanced Se2- 4p and Ni2+ 3d electronic hybridizations under
+pressure. From these results, we construct the temperature-pressure electronic
+phase diagram of NiPSe3, revealing rich physics and many similarities with
+copper oxide and iron-based superconductors.",2301.04329v1
+2023-01-12,The Role of Electrolytes in the Relaxation of Near-Surface Spin Defects in Diamond,"Quantum sensing with spin defects in diamond, such as the nitrogen-vacancy
+(NV) center, enables the detection of various chemical species on the
+nanoscale. Molecules or ions with unpaired electronic spins are typically
+probed by their influence on the NV center's spin relaxation. Whereas it is
+well-known that paramagnetic ions reduce the NV center's relaxation time
+($T_1$), here we report on the opposite effect for diamagnetic ions. We
+demonstrate that millimolar concentrations of aqueous diamagnetic electrolyte
+solutions increase the $T_1$ time of near-surface NV center ensembles compared
+to pure water. To elucidate the underlying mechanism of this surprising effect,
+single and double quantum NV experiments are performed, which indicate a
+reduction of magnetic and electric noise in the presence of diamagnetic
+electrolytes. In combination with ab initio simulations, we propose that a
+change in the interfacial band bending due to the formation of an electric
+double layer leads to a stabilization of fluctuating charges at the interface
+of an oxidized diamond. This work not only helps to understand noise sources in
+quantum systems but could also broaden the application space of quantum sensors
+towards electrolyte sensing in cell biology, neuroscience and electrochemistry.",2301.04952v2
+2023-02-28,Quantum criticality of bandwidth-controlled Mott transition,"Metallic states near the Mott insulator show a variety of quantum phases
+including various magnetic, charge ordered states and high-temperature
+superconductivity in various transition metal oxides and organic solids. The
+emergence of a variety of phases and their competitions are likely intimately
+associated with quantum transitions between the electron-correlation driven
+Mott insulator and metals characterized by its criticality, and is related to
+many central questions of condensed matter. The quantum criticality is,
+however, not well understood when the transition is controlled by the bandwidth
+through physical parameters such as pressure. Here, we quantitatively estimate
+the universality class of the transition characterized by a comprehensive set
+of critical exponents by using a variational Monte Carlo method implemented as
+an open-source innovated quantum many-body solver, with the help of established
+scaling laws at a typical bandwidth-controlled Mott transition. The criticality
+indicates a weaker charge and density instability in contrast to the
+filling-controlled transition realized by carrier doping, implying a weaker
+instability to superconductivity as well. The present comprehensive
+clarification opens up a number of routes for quantitative experimental studies
+for complete understanding of elusive quantum Mott transition and nearby
+strange metal that cultivate future design of functionality.",2302.14605v2
+2023-03-01,Influence of Structural Defects on Charge Density Waves in 1T-TaS2,"The influence of intrinsic defects of 1T-TaS2 on charge density waves (CDW)
+is studied using scanning tunneling microscopy and spectroscopy (STM, STS),
+angle-resolved photoelectron spectroscopy (ARPES), and density functional
+theory (DFT). We identify several types of structural defects and find that
+most have a local character limited to the single CDW site, with single
+exception which effectively behaves as a dopant, leading to band bending and
+affecting multiple neighboring sites. While only one type of defect can be
+observed by STM topographic imaging, all defects are easily resolved by local
+density of states (LDOS) mapping with STS. We correlate atomically-resolved STM
+periodicity of defect-free 1T-TaS2 to top sulfur atoms and introduce tiling of
+the surface using equiangular hexagon. DFT calculations (with included Coulomb
+interactions) are used to investigate the electronic structure by introducing
+sulfur vacancy or substituting sulfur with oxygen. The sulfur vacancy is
+characterized by metallic properties and is identified as an origin of one of
+observed experimentally defects. Whereas in the case of the latter, the
+oxidation of 1T-TaS2 is found to result in the loss of magnetic properties
+expected in defect-free material.",2303.00256v1
+2023-04-05,Observation of charge-to-spin conversion with giant efficiency at Ni$_{0.8}$Fe$_{0.2}$/Bi$_{2}$WO$_{6}$ interface,"Magnetization switching using spin-orbit torque offers a promising route to
+developing non-volatile memory technologies. The prerequisite, however, is the
+charge-to-spin current conversion, which has been achieved traditionally by
+harnessing the spin-orbit interaction in heavy metals, topological insulators,
+and heterointerfaces hosting a high-mobility two-dimensional electron gas.
+Here, we report the observation of charge-to-spin current conversion at the
+interface between ferromagnetic Ni$_{0.8}$Fe$_{0.2}$ and ferroelectric
+Bi$_{2}$WO$_{6}$ thin films. The resulting spin-orbit torque consists of
+damping-like and field-like components, and the estimated efficiency amounts to
+about 0.48 $\pm$ 0.02, which translates to 0.96 $\pm$ 0.04 nm$^{-1}$ in terms
+of interfacial efficiency. These numbers are comparable to contemporary
+spintronic materials exhibiting giant spin-orbit torque efficiency. We suggest
+that the Rashba Edelstein effect underpins the charge-to-spin current
+conversion on the interface side of Ni$_{0.8}$Fe$_{0.2}$. Further, we provide
+an intuitive explanation for the giant efficiency in terms of the spin-orbit
+proximity effect, which is enabled by orbital hybridization between W and Ni
+(Fe) atoms across the interface. Our work highlights that Aurivillius compounds
+are a potential addition to the emerging transition metal oxide-based
+spin-orbit materials.",2304.02751v1
+2023-04-12,CMOS + stochastic nanomagnets: heterogeneous computers for probabilistic inference and learning,"Extending Moore's law by augmenting complementary-metal-oxide semiconductor
+(CMOS) transistors with emerging nanotechnologies (X) has become increasingly
+important. One important class of problems involve sampling-based Monte Carlo
+algorithms used in probabilistic machine learning, optimization, and quantum
+simulation. Here, we combine stochastic magnetic tunnel junction (sMTJ)-based
+probabilistic bits (p-bits) with Field Programmable Gate Arrays (FPGA) to
+create an energy-efficient CMOS + X (X = sMTJ) prototype. This setup shows how
+asynchronously driven CMOS circuits controlled by sMTJs can perform
+probabilistic inference and learning by leveraging the algorithmic
+update-order-invariance of Gibbs sampling. We show how the stochasticity of
+sMTJs can augment low-quality random number generators (RNG). Detailed
+transistor-level comparisons reveal that sMTJ-based p-bits can replace up to
+10,000 CMOS transistors while dissipating two orders of magnitude less energy.
+Integrated versions of our approach can advance probabilistic computing
+involving deep Boltzmann machines and other energy-based learning algorithms
+with extremely high throughput and energy efficiency.",2304.05949v3
+2023-05-07,Evaluation of P3-type layered oxides as K-ion battery cathodes,"Given increasing energy storage demands and limited natural resources of Li,
+K-ion batteries (KIBs) could be promising next-generation systems having
+natural abundance, similar chemistry and energy density. Here, we have
+investigated the P3-type K$_{0.5}$TMO$_2$ (where TM = Ti, V, Cr, Mn, Co, or Ni)
+systems using density functional theory calculations, as potential positive
+intercalation electrodes (or cathodes) for KIBs. Specifically, we have
+identified the ground state configurations, and calculated the average
+topotactic voltages, electronic structures, on-site magnetic moments, and
+thermodynamic stabilities of all P3-K$_{0.5}$TMO$_2$ compositions and their
+corresponding depotassiated P3-TMO$_2$ frameworks. We find that K adopts the
+honeycomb or zig-zag configuration within each K-layer of all P3 structures
+considered, irrespective of the TM. In terms of voltages, we find the Co- and
+Ti-based compositions to exhibit the highest (4.59 V vs. K) and lowest (2.24 V)
+voltages, respectively, with the TM contributing to the redox behavior upon K
+(de-)intercalation. We observe all P3-K$_{0.5}$TMO$_2$ to be (meta)stable, and
+hence experimentally synthesizeable according to our 0 K convex hull
+calculations, while all depotassiated P3-TMO$_2$ configurations are unstable
+and may appear during electrochemical cycling. Also, we verified the stability
+of the prismatic coordination environment of K compared to octahedral
+coordination at the K$_{0.5}$TMO$_2$ compositions using Rouxel and cationic
+potential models. Finally, combining our voltage and stability calculations, we
+find P3-K$_x$CoO$_2$ to be the most promising cathode composition, while
+P3-K$_x$NiO$_2$ is worth exploring. Our work should contribute to the
+exploration of strategies and materials required to make practical KIBs.",2305.04299v1
+2023-05-12,Microscopic Examination of SRF-quality Nb Films through Local Nonlinear Microwave Response,"The performance of superconducting radio-frequency (SRF) cavities is
+sometimes limited by local defects. To investigate the RF properties of these
+local defects, a near-field magnetic microwave microscope is employed. Local
+third harmonic response (P3f) and its temperature-dependence and RF
+power-dependence are measured for one Nb/Cu film grown by Direct Current
+Magnetron Sputtering (DCMS) and six Nb/Cu films grown by High Power Impulse
+Magnetron Sputtering (HiPIMS) with systematic variation of deposition
+conditions. Five out of the six HiPIMS Nb/Cu films show a strong third harmonic
+response that is likely coming from a low-Tc surface defect with a transition
+temperature between 6.3 K and 6.8 K, suggesting that this defect is a generic
+feature of air-exposed HiPIMS Nb/Cu films. One possible origin of such a defect
+is grain boundaries hosting a low-Tc impurity such as oxidized Nb.
+Time-Dependent Ginzburg-Landau (TDGL) simulations are performed to better
+understand the measured third harmonic response. The simulation results show
+that the third harmonic response of RF vortex nucleation caused by surface
+defects can qualitatively explain the experimental data. Moreover, the density
+of surface defects that nucleate RF vortices, and how deep an RF vortex travels
+through these surface defects, can be extracted qualitatively from third
+harmonic response measurements. From the point of view of these two properties,
+the best Nb/Cu film for SRF applications can be identified.",2305.07746v1
+2023-05-19,Measurements of the amplitude-dependent microwave surface resistance of an Au/Nb bilayer,"Surface properties are critical to the capabilities of superconducting
+microwave devices. The native oxide of niobium-based devices is thought to
+consist of a thin normal conducting layer. To improve understanding on the
+importance of this layer, an attempt was made to replace it with a more easily
+controlled gold film. A niobium sample host microwave cavity was used to
+measure the surface resistance in continuous wave operation at 4.0 GHz and 5.2
+GHz. Sample conditions studied include temperatures ranging from 1.6 K to 4.2 K
+with RF magnetic fields on the sample surface ranging from 1 mT to the maximum
+field before the superconducting properties were lost (quench field). The
+nominal film thickness of the gold layer was increased from 0.1 nm to 2.0 nm in
+five steps to study the impact of the normal layer thickness on surface
+resistance on a single niobium substrate. The 0.1 nm film was found to reduce
+the surface resistance of the sample and to enhance the quench field. With the
+exception of the final step from a 1.5 nm gold film to 2.0 nm, the magnitude of
+the surface resistance increased substantially with gold film thickness. The
+nature of the surface resistance field-dependence appeared to be roughly
+independent from the gold layer thickness. This initial study provides new
+perspectives and suggests avenues for optimizing and designing surfaces for
+resonant cavities in particle accelerators and quantum information
+applications.",2305.12035v2
+2023-06-19,Formation of spin-orbital entangled 2D electron gas in layer delta-doped bilayer iridate La$_δ$Sr$_3$Ir$_2$O$_7$,"5$d$ transition metal oxides host a variety of exotic phases due to the
+comparable strength of Coulomb repulsion and spin-orbit coupling. Herein, by
+pursuing density-functional studies on a delta-doped quasi-two-dimensional
+iridate Sr$_3$Ir$_2$O$_7$, where a single SrO layer is replaced by LaO layer,
+we predict the formation of a spin-orbital entangled two-dimensional electron
+gas (2DEG) which is sharply confined on two IrO$_2$ layers close to the LaO
+layer. In this bilayer crystal structure, an existing potential well is further
+augmented with the inclusion of positively charged LaO layer which results in
+confining the extra valence electron made available by the La$^{3+}$ ion. The
+confined electron is bound along crystal $a$ direction and is highly mobile in
+the $bc$ plane. From the band structure point of view, now the existing
+half-filled $J_{eff}$ = 1/2 states are further electron doped to destroy the
+antiferromagnetic Mott insulating state of IrO$_2$ layers near to the
+delta-doped layer. This leads to partially occupied Ir upper-Hubbard subbands
+which host the spin-orbital entangled 2DEG. The IrO$_2$ layers far away from
+the interface remain insulating and preserve the collinear G-type magnetic
+ordering of pristine Sr$_3$Ir$_2$O$_7$. The conductivity tensors calculated
+using semi-classical Boltzmann theory at room temperature reveal that the 2DEG
+exhibits large electrical conductivity of the order of 10$^{19}$.",2306.10978v2
+2023-06-20,Optimizing the Ullmann coupling reaction efficiency on an oxide surface by metal atom addition,"The bottom-up synthesis of carbon based nanomaterials directly on
+semiconductor surfaces allows to decouple their electronic and magnetic
+properties from the substrates. However, the lack of reactivity on these
+non-metallic surfaces hinders or reduces significantly the yield of these
+reactions. Such hurdles practically precludes transferring bottom-up synthesis
+strategies onto semiconducting and insulating surfaces. Here, we achieve a high
+polymerization yield of terphenyl molecules on the semiconductor TiO$_2$(110)
+surface by incorporating cobalt atoms as catalysts in the Ullmann coupling
+reaction. Cobalt atoms trigger the debromination of 4,4-dibromo-p-terphenyl
+(DBTP) molecules on TiO$_2$(110) and the formation of an intermediate
+organometallic phase already at room-temperature (RT). As the debromination
+temperature is drastically reduced, the homo-coupling temperature is also
+significantly lowered, preventing the desorption of DBTP molecules from the
+TiO$_2$(110) surface and leading to a radical improvement on the
+poly-para-phenylene (PPP) polymerization yield. The universality of this
+mechanism is demonstrated with an iodinated terphenyl derivative (DITP), which
+shows analogous dehalogenation and polymerization temperatures with a very
+similar reaction yield. Consequently, we propose to use minute amounts of metal
+catalyst to drive forward generic bottom-up synthesis strategies on
+non-metallic surfaces.",2306.11388v1
+2023-06-27,Spin-orbital Jahn-Teller bipolarons,"Polarons and spin-orbit (SO) coupling are distinct quantum effects that play
+a critical role in charge transport and spin-orbitronics. Polarons originate
+from strong electron-phonon interaction and are ubiquitous in polarizable
+materials featuring electron localization, in particular $\mathrm{3d}$
+transition metal oxides (TMOs). On the other hand, the relativistic coupling
+between the spin and orbital angular momentum is notable in lattices with heavy
+atoms and develops in $\mathrm{5d}$ TMOs, where electrons are spatially
+delocalized. Here we combine ab initio calculations and magnetic measurements
+to show that these two seemingly mutually exclusive interactions are entangled
+in the electron-doped SO-coupled Mott insulator
+$\mathrm{Ba_2Na_{1-x}Ca_xOsO_6}$ ($0< x < 1$), unveiling the formation of
+spin-orbital bipolarons. Polaron charge trapping, favoured by the Jahn-Teller
+lattice activity, converts the Os $\mathrm{5d^1}$ spin-orbital
+$\mathrm{J_{eff}=3/2}$ levels, characteristic of the parent compound
+$\mathrm{Ba_2NaOsO_6}$ (BNOO), into a bipolaron $\mathrm{5d^2}$
+$\mathrm{J_{eff}=2}$ manifold, leading to the coexistence of different
+J-effective states in a single-phase material. The gradual increase of
+bipolarons with increasing doping creates robust in-gap states that prevents
+the transition to a metal phase even at ultrahigh doping, thus preserving the
+Mott gap across the entire doping range from $\mathrm{d^1}$ BNOO to
+$\mathrm{d^2}$ $\mathrm{Ba_2CaOsO_6}$ (BCOO).",2306.15757v1
+2023-09-27,Interfacial and thickness effects in La$_{2/3}$Sr$_{1/3}$MnO$_3$/YBa$_2$Cu$_3$O$_{7}$ superlattices,"Superlattices of correlated oxides have been used to explore interfacial
+effects and to achieve additional control over the physical properties of
+individual constituents. In this work, we present a first-principles
+perspective of the strain and thickness effects in
+La$_{2/3}$Sr$_{1/3}$MnO$_3$/YBa$_2$Cu$_3$O$_{7}$ (LSMO/YBCO) superlattices. Our
+findings indicate that the presence of epitaxial strain and LSMO leads to a
+reduction of buckling parameters of the interfacial CuO$_2$ planes, as well as
+the transfer of electrons from LSMO to YBCO. In addition, the change in Cu-3$d$
+valence is slightly dependent on the LSMO layer thickness. More interestingly,
+the in-plane ferromagnetic ground state within the CuO$_2$ planes near the
+interface is induced due to the local moments centered at the copper atoms.
+These local moments are decoupled from the charge transfer and, according to
+our calculations, appear mainly due to the Mn $3d$-O $2p$-Cu $3d$ hybridization
+being restricted to the interfacial region. The induced net magnetic ordering
+in interfacial copper atoms may have implications in the control of the
+superconducting state in the LSMO/YBCO superlattices.",2309.16013v2
+2024-01-16,"Mass inversion at the Lifshitz transition in monolayer graphene by diffusive, high-density, on-chip, doping","Experimental setups for charge transport measurements are typically not
+compatible with the ultra-high vacuum conditions for chemical doping, limiting
+the charge carrier density that can be investigated by transport methods.
+Field-effect methods, including dielectric gating and ionic liquid gating,
+achieve too low a carrier density to induce electronic phase transitions. To
+bridge this gap, we developed an integrated flip-chip method to dope graphene
+by alkali vapour in the diffusive regime, suitable for charge transport
+measurements at ultra-high charge carrier density. We introduce a cesium
+droplet into a sealed cavity filled with inert gas to dope a monolayer graphene
+sample by the process of cesium atom diffusion, adsorption and ionization at
+the graphene surface, with doping beyond an electron density of
+$4.7\times10^{14}~\mathrm{cm}^{-2}$ monitored by operando Hall measurement. The
+sealed assembly is stable against oxidation, enabling measurement of charge
+transport versus temperature and magnetic field. Cyclotron mass inversion is
+observed via the Hall effect, indicative of the change of Fermi surface
+geometry associated with the Liftshitz transition at the hyperbolic $M$ point
+of monolayer graphene. The transparent quartz substrate also functions as an
+optical window, enabling non-resonant Raman scattering. Our findings show that
+chemical doping, hitherto restricted to ultra-high vacuum, can be applied in a
+diffusive regime at ambient pressure in an inert gas environment and thus
+enable charge transport studies in standard cryogenic environments",2401.08051v1
+2024-02-07,Gaussian-process-regression-based method for the localization of exceptional points in complex resonance spectra,"Resonances in open quantum systems depending on at least two controllable
+parameters can show the phenomenon of exceptional points (EPs), where not only
+the eigenvalues but also the eigenvectors of two or more resonances coalesce.
+Their exact localization in the parameter space is challenging, in particular
+in systems, where the computation of the quantum spectra and resonances is
+numerically very expensive. We introduce an efficient machine learning
+algorithm to find exceptional points based on Gaussian process regression
+(GPR). The GPR-model is trained with an initial set of eigenvalue pairs
+belonging to an EP and used for a first estimation of the EP position via a
+numerically cheap root search. The estimate is then improved iteratively by
+adding selected exact eigenvalue pairs as training points to the GPR-model. The
+GPR-based method is developed and tested on a simple low-dimensional matrix
+model and then applied to a challenging real physical system, viz., the
+localization of EPs in the resonance spectra of excitons in cuprous oxide in
+external electric and magnetic fields. The precise computation of EPs, by
+taking into account the complete valence band structure and central-cell
+corrections of the crystal, can be the basis for the experimental observation
+of EPs in this system.",2402.05972v1
+2024-02-20,Antiferromagnetic Chern insulator with large charge gap in heavy transition-metal compounds,"Despite the discovery of multiple intrinsic magnetic topological insulators
+in recent years the observation of Chern insulators is still restricted to very
+low temperatures due to the negligible charge gaps. Here, we uncover the
+potential of heavy transition-metal compounds for realizing a collinear
+antiferromagnetic Chern insulator (AFCI) with a charge gap as large as 300 meV.
+Our analysis relies on the Kane-Mele-Kondo model with a ferromagnetic Hund
+coupling $J_{\rm H}$ between the spins of itinerant electrons and the localized
+spins of size $S$. We show that a spin-orbit coupling $\lambda_{\rm SO} \gtrsim
+0.03t$, where $t$ is the nearest-neighbor hopping element, is already large
+enough to stabilize an AFCI provided the alternating sublattice potential
+$\delta$ is in the range $\delta \approx SJ_{\rm H}$. We establish a remarkable
+increase in the charge gap upon increasing $\lambda_{\rm SO}$ in the AFCI
+phase. Using our results we explain the collinear AFCI recently found in
+monolayers of CrO and MoO with charge gaps of 1 and $50$ meV, respectively. In
+addition, we propose bilayers of heavy transition-metal oxides of perovskite
+structure as candidates to realize a room-temperature AFCI if grown along the
+$[111]$ direction and subjected to a perpendicular electric field.",2402.12918v1
+2024-02-28,Embracing Disorder in Quantum Materials Design,"Many of the most exciting materials discoveries in fundamental condensed
+matter physics are made in systems hosting some degree of intrinsic disorder.
+While disorder has historically been regarded as something to be avoided in
+materials design, it is often of central importance to correlated and quantum
+materials. This is largely driven by the conceptual and theoretical ease to
+handle, predict, and understand highly uniform systems that exhibit complex
+interactions, symmetries and band structures. In this perspective, we highlight
+how flipping this paradigm has enabled exciting possibilities in the emerging
+field of high entropy oxide (HEO) quantum materials. These materials host high
+levels of cation or anion compositional disorder while maintaining unexpectedly
+uniform single crystal lattices. The diversity of atomic scale interactions of
+spin, charge, orbital, and lattice degrees of freedom are found to emerge into
+coherent properties on much larger length scales. Thus, altering the variance
+and magnitudes of the atomic scale properties through elemental selection can
+open new routes to tune global correlated phases such as magnetism,
+metal-insulator transitions, ferroelectricity, and even emergent topological
+responses. The strategy of embracing disorder in this way provides a much
+broader pallet from which functional states can be designed for next-generation
+microelectronic and quantum information systems.",2402.18379v1
+2024-03-05,Microelectronic readout of a diamond quantum sensor,"Quantum sensors based on the nitrogen-vacancy (NV) centre in diamond are
+rapidly advancing from scientific exploration towards the first generation of
+commercial applications. While significant progress has been made in developing
+suitable methods for the manipulation of the NV centre spin state, the
+detection of the defect luminescence has so far limited the performance of
+miniaturized sensor architectures. The recent development of photoelectric
+detection of the NV centre's spin state offers a path to circumvent these
+limitations, but has to-date required research-grade low current amplifiers to
+detect the picoampere-scale currents obtained from these systems. Here we
+report on the photoelectric detection of magnetic resonance (PDMR) with NV
+ensembles using a complementary metal-oxide semiconductor (CMOS) device. The
+integrated circuit delivers a digitized output of the diamond sensor with low
+noise and 50 femtoampere resolution. This integration provides the last missing
+component on the path to a compact, diamond-based quantum sensor. The device is
+suited for continuous wave (CW) as well as pulsed operation. We demonstrate its
+functionality with DC and AC magnetometry up to several megahertz, coherent
+spin rotation and multi-axial decoupling sequences for quantum sensing.",2403.03090v2
+2003-05-14,"Insights into the function of silver as an oxidation catalyst by ab initio, atomistic thermodynamics","To help understand the high activity of silver as an oxidation catalyst,
+e.g., for the oxidation of ethylene to epoxide and the dehydrogenation of
+methanol to formaldehyde, the interaction and stability of oxygen species at
+the Ag(111) surface has been studied for a wide range of coverages. Through
+calculation of the free energy, as obtained from density-functional theory and
+taking into account the temperature and pressure via the oxygen chemical
+potential, we obtain the phase diagram of O/Ag(111). Our results reveal that a
+thin surface-oxide structure is most stable for the temperature and pressure
+range of ethylene epoxidation and we propose it (and possibly other similar
+structures) contains the species actuating the catalysis. For higher
+temperatures, low coverages of chemisorbed oxygen are most stable, which could
+also play a role in oxidation reactions. For temperatures greater than about
+775 K there are no stable oxygen species, except for the possibility of O atoms
+adsorbed at under-coordinated surface sites Our calculations rule out thicker
+oxide-like structures, as well as bulk dissolved oxygen and molecular
+ozone-like species, as playing a role in the oxidation reactions.",0305312v1
+2004-02-05,The interface between silicon and a high-k oxide,"The ability to follow Moore's Law has been the basis of the tremendous
+success of the semiconductor industry in the past decades. To date, the
+greatest challenge for device scaling is the required replacement of silicon
+dioxide-based gate oxides by high-k oxides in transistors. Around 2010 high-k
+oxides are required to have an atomically defined interface with silicon
+without any interfacial SiO2 layer. The first clean interface between silicon
+and a high-K oxide has been demonstrated by McKee et al. Nevertheless, the
+interfacial structure is still under debate. Here we report on first-principles
+calculations of the formation of the interface between silicon and SrTiO3 and
+its atomic structure. Based on insights into how the chemical environment
+affects the interface, a way to engineer seemingly intangible electrical
+properties to meet technological requirements is outlined. The interface
+structure and its chemistry provide guidance for the selection process of other
+high-k gate oxides and for controlling their growth. Our study also shows that
+atomic control of the interfacial structure can dramatically improve the
+electronic properties of the interface. The interface presented here serves as
+a model for a variety of other interfaces between high-k oxides and silicon.",0402173v1
+2010-03-24,Renormalized ionic polarizability functional applied to evaluate the molecule-oxide interactions for gas-sensing applications,"Metal-oxide sensors are widely used due to their sensitivities to different
+types of gaseous, and these sensors are suitable for long-term applications,
+even in the presence of corrosive environments. However, the microscopic
+mechanisms with quantum effects, which are required to understand the gas-oxide
+interactions are not well developed despite the oxide sensors potential
+applications in numerous fields, namely, medicine (breath-sensors), engineering
+(gas-sensors) and food processing (odor-sensors). Here, we develop a rigorous
+theoretical strategy based on the ionization energy theory (IET) to
+unambiguously explain why and how a certain gas molecule intrinsically prefers
+a particular oxide surface. We make use of the renormalized ionic displacement
+polarizability functional derived from the IET to show that the gas/surface
+interaction strength (sensing sensitivity) between an oxide surface and an
+isolated gas molecule can be predicted from the polarizability of these two
+systems. Such predictions are extremely important for the development of health
+monitoring bio-sensors, as well as to select the most suitable oxide to detect
+a particular gas with optimum sensitivity.",1003.4625v4
+2010-06-22,Three-terminal field effect devices utilizing thin film vanadium oxide as the channel layer,"Electrostatic control of the metal-insulator transition (MIT) in an oxide
+semiconductor could potentially impact the emerging field of oxide electronics.
+Vanadium dioxide is of particular interest due to the fact that the MIT happens
+in the vicinity of room temperature and it is considered to exhibit the Mott
+transition. We present a detailed account of our experimental investigation
+into three-terminal field effect transistor-like devices using thin film VO2 as
+the channel layer. The gate is separated from the channel through an insulating
+gate oxide layer, enabling true probing of the field effect with minimal or no
+interference from large leakage currents flowing directly from the electrode.
+The influence of the fabrication of multiple components of the device,
+including the gate oxide deposition, on the VO2 film characteristics is
+discussed. Further, we discuss the effect of the gate voltage on the device
+response, point out some of the unusual characteristics including temporal
+dependence. A reversible unipolar modulation of the channel resistance upon the
+gate voltage is demonstrated for the first time in optimally engineered
+devices. The results presented in this work are of relevance towards
+interpreting gate voltage response in such oxides as well as addressing
+challenges in advancing gate stack processing for oxide semiconductors.",1006.4373v1
+2010-09-14,Growth of epitaxially oriented Ag nanoislands on air-oxidized Si(111)-(7x7) surfaces: Influence of short range order on the substrate,"Clean Si(111)-(7{x7) surfaces, followed by air-exposure, have been
+investigated by reflection high energy electron diffraction (RHEED) and
+scanning tunneling microscopy (STM). Fourier transforms (FTs) of STM images
+show the presence of short range (7x7) order on the air-oxidized surface.
+Comparison with FTs of STM images from a clean Si(111)-(7x7) surface shows that
+only the 1/7th order spots are present on the air-oxidized surface. The oxide
+layer is ~ 2-3 nm thick, as revealed by cross-sectional transmission electron
+microscopy (XTEM). Growth of Ag islands on these air-oxidized Si(111)-(7x7)
+surfaces has been investigated by in-situ RHEED and STM and ex-situ XTEM and
+scanning electron microscopy. Ag deposition at room temperature leads to the
+growth of randomly oriented Ag islands while preferred orientation evolves when
+Ag is deposited at higher substrate temperatures. For deposition at 550{\deg}C
+face centered cubic Ag nanoislands grow with a predominant epitaxial
+orientation [1 -1 0]Ag || [1 -1 0]Si, (111)Ag || (111)Si along with its twin
+[-1 1 0]Ag || [1 -1 0]Si, (111)Ag || (111)Si, as observed for epitaxial growth
+of Ag on Si(111) surfaces. The twins are thus rotated by a 180{\deg} rotation
+of the Ag unit cell about the Si [111] axis. It is intriguing that Ag
+nanoislands follow an epitaxial relationship with the Si(111) substrate in
+spite of the presence of a 2-3 nm thick oxide layer between Ag and Si.
+Apparently the short range order on the oxide surface influences the
+crystallographic orientation of the Ag nanoislands.",1009.2633v1
+2013-02-05,Impact Dynamics of Oxidized Liquid Metal Drops,"With exposure to air, many liquid metals spontaneously generate an oxide
+layer on their surface. In oscillatory rheological tests, this skin is found to
+introduce a yield stress that typically dominates the elastic response but can
+be tuned by exposing the metal to hydrochloric acid solutions of different
+concentration. We systematically studied the normal impact of eutectic
+gallium-indium (eGaIn) drops under different oxidation conditions and show how
+this leads to two different dynamical regimes. At low impact velocity (or low
+Weber number), eGaIn droplets display strong recoil and rebound from the
+impacted surface when the oxide layer is removed. In addition, the degree of
+drop deformation or spreading during the impact is controlled by the oxide
+skin. We show that the scaling law known from ordinary liquids for the maximum
+spreading radius as a function of impact velocity can still be applied to the
+case of oxidized eGaIn if an effective Weber number $We^{\star}$ is employed
+that uses an effective surface tension factoring in the yield stress. In
+contrast, no influence on spreading from different oxidations conditions is
+observed for high impact velocity. This suggests that the initial kinetic
+energy is mostly damped by bulk viscous dissipation. Results from both regimes
+can be collapsed in an impact phase diagram controlled by two variables, the
+maximum spreading factor $P_m = R_0/R_m$, given by the ratio of initial to
+maximum drop radius, and the impact number $K = We^{\star}/Re^{4/5}$, which
+scales with the effective Weber number $We^{\star}$ as well as the Reynolds
+number $Re$. The data exhibit a transition from capillary to viscous behavior
+at a critical impact number $K_c \sim 0.1$.",1302.0921v1
+2013-04-11,Resistance switching in oxides with inhomogeneous conductivity,"Electric-field-induced resistance switching (RS) phenomena have been studied
+for over 60 years in metal/dielectrics/metal structures. In these experiments a
+wide range of dielectrics have been studied including binary transition metal
+oxides, perovskite oxides, chalcogenides, carbon- and silicon-based materials,
+as well as organic materials. RS phenomena can be used to store information and
+offer an attractive performance, which encompasses fast switching speeds, high
+scalability, and the desirable compatibility with Si-based
+complementary-metal-oxide-semiconductor fabrication. This is promising for
+nonvolatile memory technology, i.e. resistance random access memory (RRAM).
+However, a comprehensive understanding of the underlying mechanism is still
+lacking. This impedes a faster product development as well as an accurate
+assessment of the device performance potential. Generally speaking, RS occurs
+not in the entire dielectric but only a small, confined region, which results
+from the local variation of conductivity in dielectrics. In this review, we
+focus on the RS in oxides with such an inhomogeneous conductivity. According to
+the origin of the conductivity inhomogeneity, the RS phenomena and their
+working mechanism are reviewed by dividing them into two aspects: interface RS,
+based on the change of contact resistance at metal/oxide interface due to the
+change of Schottky barrier and interface chemical layer, and bulk RS, realized
+by the formation, connection, and disconnection of conductive channels in the
+oxides. Finally the current challenges of RS investigation and the potential
+improvement of the RS performance for the nonvolatile memories are discussed.",1304.3290v1
+2014-02-22,An Acetate Bound Cobalt Oxide Catalyst for Water Oxidation: Role of Monovalent Anions and Cations In Lowering Overpotential,"Co(II) dissolved in acetate buffer at pH 7 is found to be a good water
+oxidation catalyst (WOC) showing electrocatalytic water oxidation current
+significantly greater than Co(II) in phosphate buffer under the same conditions
+owing to the higher solubility of the former. When electrodeposited on ITO/FTO
+electrodes it forms acetate bound cobalt(II)oxide based material (Co-Ac-WOC)
+showing catalytic water oxidation current density of 0.1 mA/cm$^{2}$ at 830 mV
+and 1 mA/cm$^{2}$ at 1 V in a pH 7 buffer solution. The morphology of Co-Ac-OEC
+is investigated with AFM, HR-TEM and SEM (at different times and
+electrodeposition potentials). The chemical composition of Co-Ac-OEC is
+investigated using XPS, EDX, combustion analysis and ATR-FTIR which indicates
+that this material has a CoO core with chloride and acetate anions bound to the
+Co center. Sodium is found to be integrated in the Co-Ac-WOC. The presence of
+the sodium ions and the chloride ions lowers the onset potential for oxygen
+evolution reaction (OER) by 240 mV relative to the classic Co-Pi at pH 7. The
+lower onset potential and higher OER current lowers the exchange current
+density to 10$^{-6.7}$ in Co-Ac-WOC relative to 10$^{-8}$-10$^{-10}$ in Co-Pi
+and its derivatives.",1402.5491v1
+2015-09-29,Molecular mechanism of water permeation in helium impermeable graphene and graphene oxide membrane,"The layers of graphene oxide (GO) are found to be good for permeation of
+water but not for helium (Science 2012 335 (6067): 442-444) suggesting that the
+GO layers are dynamic in the formation of permeation route depending on the
+environment they are in (i.e, water or helium). To probe the microscopic origin
+of this observation we calculate the potential of mean force (PMF) of GO sheets
+(oxidized and reduced parts), with inter-planar distance as reaction coordinate
+in helium and water. Our PMF calculation shows that equilibrium interlayer
+distance between oxidized part of GO sheets in helium is at 4.8 {\AA} leaving
+no space for helium permeation. In contrast PMF of oxidized part of GO in water
+shows two minima one at 4.8 {\AA} and another at 6.8 {\AA} corresponding to no
+water and water filled region and thus giving rise to permeation path. The
+increased electrostatic interaction between water with the oxidized part of the
+sheet helps the sheet opening up and pushing water inside. Based on the entropy
+calculations for water trapped between graphene sheets and oxidized graphene
+sheets at different inter-sheet spacing we also show the thermodynamics of
+filling.",1509.08683v1
+2016-01-15,Surface Oxidation of the Topological Insulator Bi2Se3,"A comprehensive picture of the aging and oxidation of the (0001) surface of
+Bi2Se3 is critical to understanding the physical origin of changes in its
+topologically protected surface states. We find that surface aging in ambient
+conditions occurs in two major steps. Within two hours of exfoliation, a series
+of ~ 3.6 A high islands are observed by atomic force microscopy over
+approximate 10% of the surface. Subsequently, patch growth stops, and oxidation
+begins after the two hours and continues until one quintuple layer has been
+oxidized. X-ray photoelectron spectroscopy shows no sign of oxidation before ~
+120 minutes of exposure to air, and the oxygen 1s peak is clearly present after
+~ 190 minutes of ambient exposure. Variable angle spectroscopic ellipsometry
+also indicates that the oxidation of a full quintuple layer occurs on the time
+scale of days. These results are in good agreement with the time dependent
+changes previously observed in the surface crystal structure by second harmonic
+generation. In addition to providing the ability to non-destructively measure
+oxide on the surface of Bi2Se3 crystals, ellipsometry can be used to identify
+the thickness of Bi2Se3 flakes. These results are consistent with non-linear
+optical methods including rotational anisotropy second harmonic generation,
+which follow the time dependence of the changes to the top quintuple layer.",1601.04057v1
+2016-09-22,Selective oxidation-induced strengthening of Zr/Nb nanoscale multilayers,"The paper presents a new approach, based on controlled oxidation of nanoscale
+metallic multilayers, to produce strong and hard oxide/metal nanocomposite
+coatings with high strength and good thermal stability. The approach is
+demonstrated by performing long term annealing on sputtered Zr/Nb nanoscale
+metallic multilayers and investigating the evolution of their microstructure
+and mechanical properties by combining analytical transmission electron
+microscopy, nano-mechanical tests and finite element models. As-deposited
+multilayers were annealed at 350 C in air for times ranging between 1 - 336
+hours. The elastic modulus increased by approx. 20% and the hardness by approx.
+42% after 15 hours of annealing. Longer annealing times did not lead to changes
+in hardness, although the elastic modulus increased up to 35% after 336 hrs.
+The hcp Zr layers were rapidly transformed into monoclinic ZrO2 (in the first
+15 hours), while the Nb layers were progressively oxidised, from top surface
+down towards the substrate, to form an amorphous oxide phase at a much lower
+rate. The sequential oxidation of Zr and Nb layers was key for the oxidation to
+take place without rupture of the multi-layered structure and without coating
+spallation, as the plastic deformation of the metallic Nb layers allowed for
+the partial relieve of the residual stresses developed as a result of the
+volumetric expansion of the Zr layers upon oxidation. Moreover, the development
+of residual stresses induced further changes in mechanical properties in
+relation to the annealing time, as revealed by finite element simulations.",1609.06882v1
+2017-08-14,Structure of Native Two-dimensional Oxides on III--Nitride Surfaces,"When pristine material surfaces are exposed to air, highly reactive broken
+bonds can promote the formation of surface oxides with structures and
+properties differing greatly from bulk. Determination of the oxide structure,
+however, is often elusive through the use of indirect diffraction methods or
+techniques that probe only the outer most layer. As a result, surface oxides
+forming on widely used materials, such as group III-nitrides, have not been
+unambiguously resolved, even though critical properties can depend sensitively
+on their presence. In this work, aberration corrected scanning transmission
+electron microscopy reveals directly, and with depth dependence, the structure
+of native two--dimensional oxides that form on AlN and GaN surfaces. Through
+atomic resolution imaging and spectroscopy, we show that the oxide layers are
+comprised of tetrahedra--octahedra cation--oxygen units, similar to bulk
+$\theta$--Al$_2$O$_3$ and $\beta$--Ga$_2$O$_3$. By applying density functional
+theory, we show that the observed structures are more stable than previously
+proposed surface oxide models. We place the impact of these observations in the
+context of key III-nitride growth, device issues, and the recent discovery of
+two-dimnesional nitrides.",1708.03997v1
+2018-05-10,Evaluation of Reduced-Graphene-Oxide Aligned with WO3-Nanorods as Support for Pt Nanoparticles during Oxygen Electroreduction in Acid Medium,"Hybrid supports composed of chemically-reduced graphene-oxide-aligned with
+tungsten oxide nanowires are considered here as active carriers for dispersed
+platinum with an ultimate goal of producing improved catalysts for
+electroreduction of oxygen in acid medium. Here WO3 nanostructures are expected
+to be attached mainly to the edges of graphene thus making the hybrid structure
+not only highly porous but also capable of preventing graphene stacking and
+creating numerous sites for the deposition of Pt nanoparticles. Comparison has
+been made to the analogous systems utilizing neither reduced graphene oxide nor
+tungsten oxide component. By over-coating the reduced-graphene-oxide support
+with WO3 nanorods, the electrocatalytic activity of the system toward the
+reduction of oxygen in acid medium has been enhanced even at the low Pt loading
+of 30 microg cm-2. The RRDE data are consistent with decreased formation of
+hydrogen peroxide in the presence of WO3. Among important issues are such
+features of the oxide as porosity, large population of hydroxyl groups, high
+Broensted acidity, as well as fast electron transfers coupled to unimpeded
+proton displacements. The conclusions are supported with mechanistic and
+kinetic studies involving double-potential-step chronocoulometry as an
+alternative diagnostic tool to rotating ring-disk voltammetry.",1805.12594v1
+2012-01-25,Covalent Hybrid of Spinel Manganese-Cobalt Oxide and Gra-phene as Advanced Oxygen Reduction Electrocatalysts,"Through direct nanoparticle nucleation and growth on nitrogen doped, reduced
+graphene oxide sheets and cation substitution of spinel Co3O4 nanoparticles, a
+manganese-cobalt spinel MnCo2O4/graphene hybrid was developed as a highly
+efficient electrocatalyst for oxygen reduction reaction (ORR) in alkaline
+conditions. Electrochemical and X-ray near edge structure (XANES)
+investigations revealed that the nucleation and growth method for forming
+inorganic-nanocarbon hybrid results in covalent coupling between spinel oxide
+nanoparticles and N-doped reduced graphene oxide (N-rmGO) sheets. Carbon K-edge
+and nitrogen K-edge XANES showed strongly perturbed C-O and C-N bonding in the
+N-rmGO sheet, suggesting the formation of C-O-metal and C-N-metal bonds between
+N-doped graphene oxide and spinel oxide nanoparticles. Co L-edge and Mn L-edge
+XANES suggested substitu-tion of Co3+ sites by Mn3+, which increased the
+activity of the catalytic sites in the hybrid materials, further boosting the
+ORR activity compared to the pure cobalt oxide hybrid. The covalently bonded
+hybrid afforded much greater activity and durability than the physi-cal mixture
+of nanoparticles and carbon materials including N-rmGO. At the same mass
+loading, the MnCo2O4/N-graphene hybrid can outperform Pt/C in ORR current
+density at medium overpotentials with superior stability to Pt/C in alkaline
+solutions.",1201.5193v1
+2017-06-09,Nucleation of dislocations and their dynamics in layered oxides cathode materials during battery charging,"Defects and their interactions in crystalline solids often underpin material
+properties and functionality as they are decisive for stability, result in
+enhanced diffusion, and act as a reservoir of vacancies. Recently, lithium-rich
+layered oxides have emerged among the leading candidates for the
+next-generation energy storage cathode material, delivering 50 % excess
+capacity over commercially used compounds. Oxygen-redox reactions are believed
+to be responsible for the excess capacity, however, voltage fading has
+prevented commercialization of these new materials. Despite extensive research
+the understanding of the mechanisms underpinning oxygen-redox reactions and
+voltage fade remain incomplete. Here, using operando three-dimensional Bragg
+coherent diffractive imaging, we directly observe nucleation of a mobile
+dislocation network in nanoparticles of lithium-rich layered oxide material.
+Surprisingly, we find that dislocations form more readily in the lithium-rich
+layered oxide material as compared with a conventional layered oxide material,
+suggesting a link between the defects and the anomalously high capacity in
+lithium-rich layered oxides. The formation of a network of partial dislocations
+dramatically alters the local lithium environment and contributes to the
+voltage fade. Based on our findings we design and demonstrate a method to
+recover the original high voltage functionality. Our findings reveal that the
+voltage fade in lithium-rich layered oxides is reversible and call for new
+paradigms for improved design of oxygen-redox active materials.",1706.03031v1
+2020-12-23,Site-Selective Oxygen Vacancy Formation Derived from the Characteristic Crystal Structures of in Sn-Nb complex Oxides,"Divalent tin oxides have attracted considerable attention as novel p-type
+oxide semiconductors, which are essential for realizing future oxide electronic
+devices. Recently, p-type Sn2Nb2O7 and SnNb2O6 were developed; however,
+enhanced hole mobility by reducing defect concentrations is required for
+practical use. In this work, we investigate the correlation between the
+formation of oxygen vacancy which may reduce the hole-generation efficiency and
+hole mobility, and the crystal structure in Sn-Nb complex oxides. Extended
+X-ray absorption fine structure spectroscopy and Rietveld analysis of x-ray
+diffraction revealed the preferential formation of oxygen vacancy at the O site
+bonded to the Sn ions in both the tin niobates. Moreover, a large amount of
+oxygen vacancy around the Sn ions were found in the p-type Sn2Nb2O7, thereby
+indicating the effect of oxygen vacancy to the low hole-generation efficiency.
+The dependence of the formation of oxygen vacancy on the crystal structure can
+be elucidated from the Sn-O bond strength that is evaluated based on the bond
+valence sum and Debye temperature. The differences in the bond strengths of the
+two Sn-Nb complex oxides are correlated through the steric hindrance of Sn2+
+with asymmetric electron density distribution. This suggests the importance of
+the material design with a focus on the local structure around the Sn ions to
+prevent the formation of oxygen vacancy in p-type Sn2+ oxides.",2012.12921v1
+2018-03-03,Sulfate Radical Oxidation of Aromatic Contaminants: A Detailed Assessment of Density Functional Theory and High-Level Quantum Chemical Methods,"Advanced oxidation processes that utilize highly oxidative radicals are
+widely used in water reuse treatment. In recent years, the application of
+sulfate radical (SO$_4\cdot^-$) as a promising oxidant for water treatment has
+gained increasing attention. To understand the efficiency of SO$_4\cdot^-$ in
+the degradation of organic contaminants in wastewater effluent, it is important
+to be able to predict the reaction kinetics of various SO$_4\cdot^-$-driven
+oxidation reactions. In this study, we utilize density functional theory (DFT)
+and high-level wavefunction-based methods (including computationally-intensive
+coupled cluster methods), to explore the activation energies and kinetic rates
+of SO$_4\cdot^-$-driven oxidation reactions on a series of benzene-derived
+contaminants. These high-level calculations encompassed a wide set of reactions
+including 110 forward/reverse reactions and 5 different computational methods
+in total. Based on the high-level coupled-cluster quantum calculations, we find
+that the popular M06-2X DFT functional is significantly more accurate for
+HO-additions than for SO$_4\cdot^-$ reactions. Most importantly, we highlight
+some of the limitations and deficiencies of other computational methods, and we
+recommend the use of high-level quantum calculations to spot-check
+environmental chemistry reactions that may lie outside the training set of the
+M06-2X functional, particularly for water oxidation reactions that involve
+SO$_4\cdot^-$ and other inorganic species.",1803.01227v1
+2018-08-30,Modeling Selective Intergranular Oxidation of Binary Alloys,"Intergranular attack of alloys under hydrothermal conditions is a complex
+problem that depends on metal and oxygen transport kinetics via solid-state and
+channel-like pathways to an advancing oxidation front. Experiments reveal very
+different rates of intergranular attack and minor element depletion distances
+ahead of the oxidation front for nickel-based binary alloys depending on the
+minor element. For example, a significant Cr depletion up to 9 microns ahead of
+grain boundary crack tips were documented for Ni-5Cr binary alloy, in contrast
+to relatively moderate Al depletion for Ni-5Al (~100s of nm). We present a
+mathematical kinetics model that adapts Wagner's model for thick film growth to
+intergranular attack of binary alloys. The transport coefficients of elements
+O, Ni, Cr, and Al in bulk alloys and along grain boundaries were estimated from
+the literature. For planar surface oxidation, a critical concentration of the
+minor element can be determined from the model where the oxide of minor element
+becomes dominant over the major element. This generic model for simple grain
+boundary oxidation can predict oxidation penetration velocities and minor
+element depletion distances ahead of the advancing front that are comparable to
+experimental data. The significant distance of depletion of Cr in Ni-5Cr in
+contrast to the localized Al depletion in Ni-5Al can be explained by the model
+due to the combination of the relatively faster diffusion of Cr along the grain
+boundary and slower diffusion in bulk grains, relative to Al.",1808.10397v1
+2020-03-06,Anodic Decomposition of Surface Films on High Voltage Spinel Surfaces -- Density Function Theory and Experimental Study,"Oxidative decomposition of organic-solvent-based liquid electrolytes at
+cathode material interfaces has been identified as a main reason for rapid
+capacity fade in high-voltage lithium ion batteries. The evolution of ""cathode
+electrolyte interphase: (CEI) films, partly or completely consisting of
+electrolyte decomposition products, has also recently been demonstrated to be
+correlated with battery cycling behavior at high potentials. Using Density
+Functional Theory (DFT) calculations, the hybrid PBE0 functional, and the (001)
+surfaces of spinel oxides as models, we examine these two interrelated
+processes. Consistent with previous calculations, ethylene carbonate (EC)
+solvent molecules are predicted to be readily oxidized on the Li(x)Mn(2)O(4)
+(001) surface at modest operational voltages, forming adsorbed organic
+fragments. Further oxidative decompostion of such CEI fragments to release CO2
+gas is however predicted to require higher voltages consistent with
+Li(x)Ni(0.5)Mn(1.5)O(4) (LNMO) at smaller x values. We argue that multi-step
+reactions, involving first formation of CEI films and then further oxidization
+of CEI at higher potentials, are most relevant to capacity fade. Mechanisms
+associated with dissolution or oxidation of native Li2CO3 films, which is
+removed before the electrolyte is in contact with oxide surfaces, are also
+explored.",2003.03443v1
+2020-08-12,O2-Oxidation of Individual Graphite and Graphene Nanoparticles in the 1200 to 2200 K Range: Particle-to-Particle Variations and the Evolution of the Reaction Rates and Optical Properties,"The kinetics for O2 oxidation of individual graphite and graphene platelet
+nanoparticles (NPs) were studied as a function of temperature (1200 to 2200 K)
+at varying oxygen partial pressures, using a single nanoparticle mass
+spectrometry method. NP temperature (TNP) was measured by measuring the NP
+thermal emission spectra during the kinetics studies. The initial oxidation
+efficiency is found to peak in the 1200 to 1500 K range, dropping by an order
+of magnitude as TNP was increased above 2000 K. There were large NP-to-NP
+variations in the oxidation rates, attributed to variations in the NP surface
+structure. In addition, the oxidation efficiencies decreased,
+non-monotonically, as the NPs reacted, by factors of between 10 and 300. This
+evolution of reactivity is attributed to changes in the NP surface structure
+due to the combination of oxidation and annealing. The optical properties,
+including wavelength dependence of the emissivity, and the absorption cross
+section for the 532 nm heating laser, also tend to evolve as the NPs oxidize,
+but differently for each individual NP, presumably reflecting differences in
+the initial structures, and how they evolve under different reaction
+conditions.",2008.05078v1
+2020-10-25,Coulombically-stabilized oxygen hole polarons enable fully reversible oxygen redox,"Stabilizing high-valent redox couples and exotic electronic states
+necessitate an understanding of the stabilization mechanism. In oxides, whether
+they are being considered for energy storage or computing, highly oxidized
+oxide-anion species rehybridize to form short covalent bonds and are related to
+significant local structural distortions. In intercalation oxide electrodes for
+batteries, while such reorganization partially stabilizes oxygen redox, it also
+gives rise to substantial hysteresis. In this work, we investigate oxygen redox
+in layered Na2-XMn3O7, a positive electrode material with ordered Mn vacancies.
+We show that coulombic interactions between oxidized oxide-anions and the
+interlayer Na vacancies can disfavor rehybridization and stabilize hole
+polarons on oxygen at 4.2 V vs. Na/Na+. These coulombic interactions provide
+thermodynamic energy saving as large as O-O covalent bonding and enable ~ 40 mV
+voltage hysteresis over multiple electrochemical cycles with negligible voltage
+fade. Our results establish a complete picture of redox energetics by
+highlighting the role of coulombic interactions across several atomic distances
+and suggest avenues to stabilize highly oxidized oxygen for applications in
+energy storage and beyond.",2010.13107v1
+2021-05-11,Combinatorial screening of crystal structure in Ba-Sr-Mn-Ce perovskite oxides with ABO3 stoichiometry,"ABO3 oxides with the perovskite-related structures are attracting significant
+interest due to their promising physical and chemical properties for many
+applications requiring tunable chemistry, including fuel cells, catalysis, and
+electrochemical water splitting. Here we report on the crystal structure of the
+entire family of perovskite oxides with ABO3 stoichiometry, where A and B are
+Ba, Sr, Mn, Ce. Given the vast size of this chemically complex material system,
+exploration for stable perovskite-related structures with respect to its
+constituent elements and annealing temperature is performed by combinatorial
+pulsed laser deposition and spatially-resolved characterization of composition
+and structure. As a result of this high-throughput experimental study, we
+identify hexagonal perovskite-related polytypic transformation as a function of
+composition in the Ba1-xSrxMnO3 oxides after annealing at different
+temperatures. Furthermore, a hexagonal perovskite-related polytype is observed
+in a narrow composition-temperature range of the BaCexMn1-xO3 oxides. In
+contrast, a tetragonally-distorted perovskite is observed across a wider range
+of compositions and annealing temperatures in the Sr1-xCexMnO3 oxides. This
+structure stability is further enhanced along the BaCexMn1-xO3 - Sr1-xCexMnO3
+pseudo-binary tie-line at x=0.25 by increasing Ba-incorporation and annealing
+temperature. These results indicate that the BaCexMn1-xO3 - Sr1-xCexMnO3
+pseudo-binary oxide alloys (solid solutions) with tetragonal perovskite
+structure and broad composition-temperature range of stability are promising
+candidates for thermochemical water splitting applications.",2105.05206v2
+2021-05-21,"Cerium (III) and (IV) containing mesoporous glasses/alginate beads for bone regeneration: bioactivity, biocompatibility and reactive oxygen species activity","A very small number of biomaterials investigated for bone regeneration was
+reported as able to prevent the oxidative stress. In this study beads based on
+alginate hydrogel and mesoporous glasses (MG) containing different amounts of
+cerium oxides (Ce3+/Ce4+) exhibiting antioxidant properties were investigated
+as a good approach to mimic the action of antioxidant enzymes in our organism.
+The effect of cerium contents on the bioactivity and biocompatibility of beads
+were investigated. Moreover, the potential capability of Ce-containing MG to
+prevent the oxidative stress caused by the activity of reactive oxygen species
+(ROS) was here investigated for the first time. The increment of cerium oxide
+from 1.2, to 3.6 and 5.3 mol-% decreases the surface area and porosity of MG
+and increases the catalase mimetic activity after 168 h. Swelling tests in
+different cell culture media (D- and {\alpha}-MEM) demonstrated the rehydration
+capability of beads. The presence of beads with the highest Ce-contents (3.6
+and 5.3 %) improved the proliferation of pre-osteoblastic cells MC3T3-C1 cells.
+However, the cell differentiation decreased when increased the cerium content.
+Lactate dehydrogenase assays showed beads are cytocompatible materials.
+Moreover, oxidative stress tests with H2O2 showed a better response related to
+cell viability and the elimination of oxidant species when increased cerium
+content. Beads of glasses with 1.2 and 3.6 % of CeO2 are excellent candidates
+as bioactive scaffolds for bone regeneration capable of counteract the
+oxidative stress.",2105.10231v1
+2021-10-24,Investigation of the Imperfect Interface at the Si/GaAs Heterojunction Formed by Ultra-Thin Oxide Interfacial Layer,"The structure property of non-ideal Si/GaAs heterostructures that were
+integrated with the ultra-thin oxide (UO) tunneling interfacial layer has been
+systematically investigated. Si nanomembranes (NMs) were oxidized in different
+time periods prior to the hetero-integration process to create the non-ideal
+single-side passivated Si/GaAs heterostructure. The atomic level oxygen
+distribution and the degree of oxygen content in Si NM and GaAs were carefully
+investigated using the atom probe tomography (APT) and X-ray photoelectron
+spectroscopy (XPS) to trace the changes in chemical composition and reactional
+mechanism across the UO interface when the surface of Si NM was exposed to air
+for different period of time. The negatively induced charges at the UO layer
+caused the oxygen diffusion to GaAs layer and formed the unwanted GaAs oxide
+layer. This native oxide stack noticeably degraded the thermal properties of
+the Si/GaAs heterostructure as Si NMs were more oxidized. This study revealed
+that the poor surface passivation on the one side of the heterointerface leads
+to a both-side oxidation, thus severely deteriorating the transport properties
+across the heterojunction that is formed with the UO layer.",2110.12496v1
+2022-07-29,Theory of layered-oxide cathode degradation in Li-ion batteries by oxidation-induced cation disorder,"Disorder-driven degradation phenomena, such as structural phase
+transformations and surface reconstructions, can significantly reduce the
+lifetime of Li-ion batteries, especially those with nickel-rich layered-oxide
+cathodes. We develop a general free energy model for layered-oxide
+ion-intercalation materials as a function of the degree of disorder, which
+represents the density of defects in the host crystal. The model accounts for
+defect core energies, long-range dipolar electrostatic forces, and
+configurational entropy of the solid solution. In the case of nickel-rich
+oxides, we hypothesize that nickel with a high concentration of defects is
+driven into the bulk by electrostatic forces as oxidation reactions at the
+solid-electrolyte interface reduce nickel and either evolve oxygen gas or
+oxidize the organic electrolyte at high potentials (>4.4V vs. Li/Li+). The
+model is used in battery cycling simulations to describe the extent of cathode
+degradation when using different voltage cutoffs, in agreement with
+experimental observations that lower-voltage cycling can substantially reduce
+cathode degradation. The theory provides a framework to guide the development
+of cathode compositions, coatings and electrolytes to enhance rate capability
+and enhance battery lifetime. The general theory of cation-disorder formation
+may also find applications in electrochemical water treatment and ion
+separations, such as lithium extraction from brines, based on competitive ion
+intercalation in battery materials.",2207.14699v3
+2023-02-13,Growth of Zr/ZrO2 core-shell structures by Fast Thermal Oxidation,"This research has been conducted to characterize and validate the resistive
+heating as a synthesis method for zirconium oxides (ZrO$_2$). A wire of Zr has
+been oxidized to form a core shell structure, in which the core is the metal
+wire, and the shell is an oxide layer around 10${\mu}$m thick. The
+characterization This research has been conducted to characterize and validate
+the resistive heating as a synthesis method for zirconium oxides (ZrO$_2$). A
+wire of Zr has been oxidized to form a core shell structure, in which the core
+is the metal wire, and the shell is an oxide layer around 10${\mu}$m thick. The
+characterization of the samples has been performed by means of Scanning
+Electron Microscopy (SEM). The chemical composition was analysed by X-ray
+spectroscopy (EDX). X-ray diffraction (XRD) and Raman spectroscopy have been
+used to assess crystallinity and crystal structure. Photoluminescence (PL) and
+cathodoluminescence (CL) measurements have allowed us to study the distribution
+of defects along the shell, and to confirm the degree of uniformity. The oxygen
+vacancies, either as isolated defects or forming complexes with impurities,
+play a determinant role in the luminescent processes. Colour centres, mainly
+electron centres as F, F$_A$ and F$_{AA}$, give rise to several visible
+emissions extending from blue to green, with main components around 2eV,
+2.4-2.5eV and 2.7eV. The differences between PL and CL are also discussed.",2302.06296v1
+2023-04-21,Constraining the Origin of Mars via Simulations of Multi-Stage Core Formation,"It remains an elusive goal to simultaneously model the astrophysics of Solar
+System accretion while reproducing the mantle chemistry of more than one inner
+terrestrial planet. Here, we used a multistage core-mantle differentiation
+model based on Rubie et al. (2011,2015) to track the formation and composition
+of Earth and Mars in various Grand Tack formation simulations. Prior studies
+showed that in order to recreate Earth's mantle composition, it must grow first
+from reduced (Fe-metal rich and O-poor) building blocks and then from
+increasingly oxidized (FeO rich) material. This accretion chemistry occurs when
+an oxidation gradient exists across the disk so that the innermost solids are
+reduced and increasingly oxidized material is found at greater heliocentric
+distances. For a suite of Grand Tack simulations, we investigated whether Earth
+and Mars can be simultaneously produced by the same oxidation gradient. Our
+model did not find an oxidation gradient that simultaneously reproduces the
+mantle composition of Earth and Mars. Due to its small mass and rapid
+formation, the formation history of Mars-like planets is very stochastic which
+decreases the likelihood of compatibility with an Earth-producing oxidation
+gradient in any given realization. To reconcile the accretion history and ideal
+chemistry of the Mars-like planet with the oxidation gradient of an
+Earth-producing disk, we determined where in the Earth-producing disk Mars must
+have formed. We find that the FeO-rich composition of the Martian mantle
+requires that Mars' building blocks must originate exterior to 1.0 astronomical
+units (AU).",2304.11236v1
+2023-05-05,Shock induced atomisation of a liquid metal droplet,"The present study uses Galinstan as a test fluid to investigate the
+shock-induced aerobreakup of a liquid metal droplet in a high Weber number
+regime (We ~ 400 - 8000). Atomization dynamics is examined for three test
+environments: oxidizing (Galinstan-air), inert (Galinstan-nitrogen), and
+conventional fluids (DI water-air). Due to the readily oxidizing nature of
+liquid metals, their atomization in an industrial scale system is generally
+carried in inert atmosphere conditions. However, no previous study has
+considered gas-induced secondary atomization of liquid metals in inert
+conditions. Due to experimental challenges associated with molten metals,
+laboratory scale models are generally tested for conventional fluids like DI
+water, liquid fuels, etc. The translation of results obtained from conventional
+fluid to liquid metal atomization is rarely explored. Here a direct multi-scale
+spatial and temporal comparison is provided between the atomization dynamics of
+conventional fluid and liquid metals under oxidizing and inert conditions. The
+liquid metal droplet undergoes breakup through Shear-Induced Entrainment (SIE)
+mode for the studied range of Weber number values. The prevailing mechanism is
+explained based on the relative dominance of droplet deformation and KH wave
+formation. The study provides quantitative and qualitative similarities for the
+three test cases and explains the differences in morphology of fragmenting
+secondary droplets in the oxidizing test case (Galinstan-air) due to rapid
+oxidation of the fragmenting ligaments. A phenomenological framework is
+postulated for predicting the morphology of secondary droplets. The formation
+of flake-like secondary droplets in the Galinstan air test case is based on the
+oxidation rate of liquid metals and the properties of the oxide layer formed on
+the atomizing ligament surface.",2305.03525v1
+2023-05-23,Modeling of Surface Damage at the Si/SiO$_2$-interface of Irradiated MOS-capacitors,"Surface damage caused by ionizing radiation in SiO$_2$ passivated silicon
+particle detectors consists mainly of the accumulation of a positively charged
+layer along with trapped-oxide-charge and interface traps inside the oxide and
+close to the Si/SiO$_2$-interface. High density positive interface net charge
+can be detrimental to the operation of a multi-channel $n$-on-$p$ sensor since
+the inversion layer generated under the Si/SiO$_2$-interface can cause loss of
+position resolution by creating a conduction channel between the electrodes. In
+the investigation of the radiation-induced accumulation of oxide charge and
+interface traps, a capacitance-voltage characterization study of n/$\gamma$-
+and $\gamma$-irradiated Metal-Oxide-Semiconductor (MOS) capacitors showed that
+close agreement between measurement and simulation were possible when oxide
+charge density was complemented by both acceptor- and donor-type deep interface
+traps with densities comparable to the oxide charges. Corresponding inter-strip
+resistance simulations of a $n$-on-$p$ sensor with the tuned oxide charge
+density and interface traps show close agreement with experimental results. The
+beneficial impact of radiation-induced accumulation of deep interface traps on
+inter-electrode isolation may be considered in the optimization of the
+processing parameters of isolation implants on $n$-on-$p$ sensors for the
+extreme radiation environments.",2305.14316v3
+2023-07-12,Multimodal Operando X-ray Mechanistic Studies of a Bimetallic Oxide Electrocatalyst in Alkaline Media,"Furthering the understanding of the catalytic mechanisms in the oxygen
+reduction reaction (ORR) is critical to advancing and enabling fuel cell
+technology. In this work, we use multimodal operando synchrotron X-ray
+diffraction (XRD) and resonant elastic X-ray scattering (REXS) to investigate
+the interplay between the structure and oxidation state of a Co-Mn spinel oxide
+electrocatalyst, which has previously shown ORR activity that rivals Pt in
+alkaline fuel cells. During cyclic voltammetry, the electrocatalyst exhibited a
+reversible and rapid increase in tensile strain at low potentials, suggesting
+robust structural reversibility and stability of Co-Mn oxide electrocatalysts
+during normal fuel cell operating conditions. At low potential holds, exploring
+the limit of structural stability, an irreversible tetragonal-to-cubic phase
+transition was observed, which may be correlated to reduction in both Co and Mn
+valence states. Meanwhile, joint density-functional theory (JDFT) calculations
+provide insight into how reactive adsorbates induce strain in spinel oxide
+nanoparticles. Through this work, strain and oxidation state changes that are
+possible sources of degradation during the ORR in Co-Mn oxide electrocatalysts
+are uncovered, and the unique capabilities of combining structural and chemical
+characterization of electrocatalysts in multimodal operando X-ray studies are
+demonstrated.",2307.05912v1
+2023-09-07,Enhanced strength-ductility combination by introducing bimodal grains structures in high-density oxide dispersion strengthened FeCrAl alloys fabricated by spark plasma sintering technology,"Oxide dispersion strengthened FeCrAl alloys dispersed high-density
+nano-oxides in the matrix show outstanding corrosion resistance and mechanical
+properties. However, ODS FeCrAl alloys achieve the high strength generally at
+the expense of ductility in some way. Here, a method by introducing a bimodal
+grain structure was designed to overcome the strength-ductility tradeoff. In
+this work, ODS FeCrAl alloys were successfully fabricated through various
+mechanical alloying time, combined with spark plasma sintering under the vacuum
+of less than 4Pa. Microstructural characterization showed that the average
+grains size and nano-oxides size decrease gradually, and the density of
+nano-oxides increases, as the milling time increases. Mechanical properties
+revealed that both the strength and ductility were significantly synergistic
+enhanced with increasing milling time. The bimodal grain distribution
+characterized by electron backscatter diffraction (EBSD) (vacuum degree was
+less than 5E-5pa) was beneficial for the activation of the back stress
+strengthening and the annihilation of these microcracks, thus achieving the
+excellent ductility (27.65%). In addition, transmission electron microscope
+(TEM) characterization under the vacuum degree of less than 10-6pa illustrated
+that ultra-high-density nano-oxides (9.61E22/m3) was crucial for enhancing the
+strength of ODS FeCrAl alloys (993MPa). The strengthening mechanism
+superposition, based on the model of nano-oxides interrelated with the
+dislocation, illustrated an excellent agreement with experimental results from
+yield strength strengthening mechanisms. To our best knowledge, H40 (milled for
+40h, and sintered at 1100C) alloy presents the outstanding strength with the
+exceptional ductility among all studied ODS FeCrAl alloys, which makes it the
+promising cladding materials for the accident tolerant fuel cladding.",2309.03703v1
+2024-01-26,E-Beam Induced Micropattern Generation and Amorphization of L-Cysteine-Functionalized Graphene Oxide Nano-composites,"The evolution of dynamic processes in graphene-family materials are of great
+interest for both scientific purposes and technical applications. Scanning
+electron microscopy and transmission electron microscopy outstand among the
+techniques that allow both observing and controlling such dynamic processes in
+real time. On the other hand, functionalized graphene oxide emerges as a
+favorable candidate from graphene-family materials for such an investigation
+due to its distinctive properties, that encompass a large surface area, robust
+thermal stability, and noteworthy electrical and mechanical properties after
+its reduction. Here, we report on studies of surface structure and adsorption
+dynamics of L-Cysteine on electrochemically exfoliated graphene oxides basal
+plane. We show that electron beam irradiation prompts an amorphization of
+functionalized graphene oxide along with the formation of micropatterns of
+controlled geometry composed of L-Cysteine-Graphene oxide nanostructures. The
+controlled growth and predetermined arrangement of micropatterns as well as
+controlled structure disorder induced by e beam amorphization, in its turn
+potentially offering tailored properties and functionalities paving the way for
+potential applications in nanotechnology, sensor development, and surface
+engineering. Our findings demonstrate that graphene oxide can cover L-Cysteine
+in such a way to provide a control on the positioning of emerging
+microstructures about 10-20 um in diameter. Besides, Raman and SAED measurement
+analyses yield above 50% amorphization in a material. The results of our
+studies demonstrate that such a technique enables the direct creation of
+micropatterns of L-Cysteine-Graphene oxide eliminating the need for complicated
+mask patterning procedures.",2401.14783v1
+2019-06-02,Oxidation of Monolayer WS$_{2}$ in Ambient is a Photoinduced Process,"We have studied the ambient air oxidation of chemical vapor deposition (CVD)
+grown monolayers of the semiconducting transition metal dichalcogenide (S-TMD)
+WS$_{2}$ using optical microscopy, laser scanning confocal microscopy (LSCM),
+photoluminescence (PL) spectroscopy, and atomic force microscopy (AFM).
+Monolayer WS$_{2}$ exposed to ambient conditions in the presence of light
+(typical laboratory ambient light for weeks, or typical PL spectroscopy map),
+exhibits damage due to oxidation which can be detected with the LSCM and AFM;
+though may not be evident in conventional optical microscopy due to poorer
+contrast and resolution. Additionally, this oxidation was not random, and
+correlated with 'high-symmetry' and red-shifted areas in the PL spectroscopy
+map - areas thought to contain a higher concentration of sulfur vacancies. In
+contrast, samples kept in ambient and darkness showed no signs of oxidation for
+up to 10 months. Low-irradiance/fluence experiments showed that samples
+subjected to excitation energies at or above the trion excitation energy (532
+nm/2.33 eV and 660 nm/1.88 eV) oxidized in as little as 7 days, even for
+irradiances and fluences eight and four orders of magnitude lower
+(respectively) than previously reported. No significant oxidation was observed
+for 760 nm/1.63 eV light exposure, which lies below the trion excitation energy
+in WS$_{2}$. The strong wavelength dependence and apparent lack of irradiance
+dependence suggests that ambient oxidation of WS$_{2}$ is initiated by
+photon-mediated electronic band transitions, that is, photo-oxidation. These
+findings have important implications for prior, present and future studies
+concerning S-TMDs measured, stored or manipulated in ambient conditions.",1906.00375v2
+2018-06-18,Significantly enhanced photocatalytic degradation of Methylene Blue using rGO-SnO2 nanocomposite under natural sunlight and UV light irradiation,"In this paper, we report the synthesis of reduced Graphene Oxide-Tin Oxide
+nanocomposite and the effectiveness of this composite in decolorizing and
+degrading Methylene Blue (MB). Tin Oxide was prepared by liquid phase
+co-precipitation method and reduced Graphene Oxide-Tin Oxide (rGO-SnO2)
+nanocomposite was prepared by solution mixing method. Tin Oxide nanoparticles
+(NPs) have been ardently investigated as photocatalyst for water purification
+and environment decontamination but the photon generated electron and hole pair
+(EHP) recombination is one of the limiting factors. Reduced Graphene Oxide-Tin
+Oxide (rGO-SnO2) nanocomposite is very efficient to overcome this limitation
+for photocatalytic application. The as-synthesized GO, SnO2, GO-SnO2, rGO and
+rGO-SnO2 nanocomposite were characterized by X-ray Diffraction, Scanning
+Electron Microscopy, Energy Dispersive X-ray spectroscopy and Fourier Transform
+Infrared spectroscopy. The XRD data confirms the sharp peak at 2Theta=10.44
+degree corresponding to (002) reflection of GO with interlayer d spacing of
+8.46 Angstrom indication of successful preparation of GO by oxidation of
+graphite. Moreover, the diffraction peak shifts from 2Theta=10.44 degree to
+2Theta=23.31 degree confirm successful synthesis of rGO as well. SEM image
+shows the morphology of all the photocatalysts. EDX studies are carried out to
+investigate the elemental composition and purity of the sample by giving all
+the elements present in the nanomaterials. The presence of functional groups
+was identified by FTIR. The rGO-SnO2 (1:10) nanocomposite shows an efficient
+photodegradation efficiency of ~94% and ~95% under natural sunlight and UV
+light irradiation respectively for Methylene Blue (MB) within 15 minutes.
+Furthermore, the degradation kinetics of MB is also studied in this paper as
+well.",1808.02107v1
+2024-02-02,"Size, nanostructure, and composition dependence of bimetallic Au-Pd supported on ceria-zirconia mixed oxide catalysts for selective oxidation of benzyl alcohol","A bimetallic Au-Pd catalyst supported on ceriazirconia with Au:Pd molar ratio
+0.8 has been synthesized using a simultaneous deposition-precipitation method
+and oxidized at 250, 450, and 700 $^\circ$C in order to modify its particle
+size, nanostructure, and composition. Combined Xray energy dispersive
+spectroscopy and Xray photoelectron spectroscopy analysis clearly evidence that
+the bimetallic Au-Pd catalyst oxidized at 250 $^\circ$C is made up of a mixture
+of monometallic Au and Pd and bimetallic Au-Pd nanoparticles with Au:Pd ratios
+varying over a wide range. Increasing oxidation temperature leads to a stronger
+interaction between Au and Pd. Meanwhile, a slight increase of particle size
+and a narrowing of the Au:Pd ratio in the bimetallic nanoparticles take place.
+Compared with titania and activated carbon supports, the resistance against
+sintering at high temperatures of Au-Pd metal particles supported on
+ceriazirconia is proven to be higher. A synergistic effect has been observed
+for selective oxidation of benzyl alcohol on these catalysts. The catalytic
+activity decreases only slightly after oxidation at 450 $^\circ$C. However,
+oxidation at 700 $^\circ$C results in much lower catalytic activity. Migration
+of Pd onto Au particles during oxidation of benzyl alcohol enhances the
+catalytic activity of a physical mixture of monometallic Au and Pd supported on
+ceriazirconia catalysts. This fact, jointly with an analysis of the intrinsic
+activity, reveals the influence of the actual nature of Au-Pd interactions in
+the bimetallic particles, which points to higher activity of Au@Pd or Au@Pd@Pd
+nanostructures on ceria-zirconia support.",2403.03958v1
+2005-12-21,"Poly-MTO, {(CH_3)_{0.92} Re O_3}_\infty, a Conducting Two-Dimensional Organometallic Oxide","Polymeric methyltrioxorhenium, {(CH_{3})_{0.92}ReO_{3}}_{\infty} (poly-MTO),
+is the first member of a new class of organometallic hybrids which adopts the
+structural pattern and physical properties of classical perovskites in two
+dimensions (2D). We demonstrate how the electronic structure of poly-MTO can be
+tailored by intercalation of organic donor molecules, such as
+tetrathiafulvalene (TTF) or bis-(ethylendithio)-tetrathiafulvalene (BEDT-TTF),
+and by the inorganic acceptor SbF$_3$. Integration of donor molecules leads to
+a more insulating behavior of poly-MTO, whereas SbF$_3$ insertion does not
+cause any significant change in the resistivity. The resistivity data of pure
+poly-MTO is remarkably well described by a two-dimensional electron system.
+Below 38 K an unusual resistivity behavior, similar to that found in doped
+cuprates, is observed: The resistivity initially increases approximately as
+$\rho \sim$ ln$(1/T$) before it changes into a $\sqrt{T}$ dependence below 2 K.
+As an explanation we suggest a crossover from purely two-dimensional
+charge-carrier diffusion within the \{ReO$_2$\}$_{\infty}$ planes at high
+temperatures to three-dimensional diffusion at low temperatures in a
+disorder-enhanced electron-electron interaction scenario (Altshuler-Aronov
+correction). Furthermore, a linear positive magnetoresistance was found in the
+insulating regime, which is caused by spatial localization of itinerant
+electrons at some of the Re atoms, which formally adopt a $5d^1$ electronic
+configuration. X-ray diffraction, IR- and ESR-studies, temperature dependent
+magnetization and specific heat measurements in various magnetic fields suggest
+that the electronic structure of poly-MTO can safely be approximated by a
+purely 2D conductor.",0512544v1
+2007-02-05,Quantum phase transitions in magnetism and superconductivity: emergent spin topology seen with neutrons,"Magnetic spins and charges interact strongly in high-temperature
+superconductors. New physics emerges as layers of copper oxide are tuned
+towards the boundary of the superconducting phase. As the pseudogap increases
+the characteristic spin excitation energy decreases. We show that our
+well-annealed YBa2Cu3O6+x (YBCO6+x) single crystals are orthorhombic and
+superconducting but not antiferromagnetically ordered. Near the critical
+concentration for superconductivity for x = 0.35 the spins fluctuate on two
+energy scales, one a relaxational spin response at ~2 meV and the other a slow
+central mode that is resolution-limited in energy (<0.08 meV) but broad in
+momentum. The gradual formation on cooling of a central mode over a range of
+momenta suggests that the spin ground state from which coherent superconducting
+pairing emerges may be quantum disordered. We show that YBCO6.35 adopts a
+homogeneous state that consists of highly-organized frozen sub-critical
+three-dimensional spin correlations. The continuous spin evolution indicates
+that a single quantum state occurs in contrast to claims from site-based probes
+that lightly doped YBCO undergoes a transition to antiferromagnetic Bragg order
+followed by a sharp transition to a cluster glass phase. For x = 0.35, where Tc
+= 18 K is reduced to 1/5 of Tcmax, the spin ground state is reached without a
+sharp transition and consists of short correlations extending over only 8
+Angstrom between cells and 42 Angstrom within the planes. Polarized neutrons
+show the angular spin distribution to be isotropic unlike the AF insulator.
+Since moment is conserved we interpret this as evidence for hole-induced spin
+rotations rather than decay.",0702062v2
+2007-03-12,"Metal-insulator (fermion-boson)-crossover origin of pseudogap phase of cuprates I: anomalous heat conductivity, insulator resistivity boundary, nonlinear entropy","Among all experimental observations of cuprate physics, the
+metal-insulator-crossover (MIC), seen in the pseudogap (PG) region of the
+temperature-doping phase diagram of copper-oxides under a strong magnetic
+field, when the superconductivity is suppressed, is most likely the most
+intriguing one. Since it was expected that the PG-normal state for these
+materials, as for conventional superconductors, is conducting. This MIC,
+revealed in such phenomena as heat conductivity downturn, anomalous Lorentz
+ratio, insulator resistivity boundary, nonlinear entropy, resistivity
+temperature upturn, insulating ground state, nematicity- and stripe-phases and
+Fermi pockets, unambiguously indicates on the insulating normal state, from
+which the high-temperature superconductivity (HTS) appears. In the present work
+(article I), we discuss the MIC phenomena mentioned in the title of article.
+The second work (article II) will be devoted to discussion of other listed
+above MIC phenomena and also to interpretation of the recent observations in
+the hidden magnetic order and scanning tunneling microscopy (STM) experiments
+spin and charge fluctuations as the intra PG and HTS pair ones. We find that
+all these MIC (called in the literature as non-Fermi liquid) phenomena can be
+obtained within the Coulomb single boson and single fermion two liquid model,
+which we recently developed, and the MIC is a crossover of single fermions into
+those of single bosons. We show that this MIC originates from bosons of Coulomb
+two liquid model and fermions, whose origin is these bosons. At an increase of
+doping up to critical value or temperature up to PG boundary temperature, the
+boson system undegoes bosonic insulator - bosonic metal - fermionic metal
+transitions.",0703290v3
+2007-10-03,Gapped itinerant spin excitations account for missing entropy in the hidden order state of URu$_2$Si$_2$,"One of the primary goals of modern condensed matter physics is to elucidate
+the nature of the ground state in various electronic systems. Many correlated
+electron materials, such as high temperature superconductors, geometrically
+frustrated oxides, and low-dimensional magnets are still the objects of
+fruitful study because of the unique properties which arise due to poorly
+understood many-body effects. Heavy fermion metals - materials which have high
+effective electron masses due to these effects - represent a class of materials
+with exotic properties, such as unusual magnetism, unconventional
+superconductivity, and ""hidden order"" parameters. The heavy fermion
+superconductor URu2Si2 has held the attention of physicists for the last two
+decades due to the presence of a ""hidden order"" phase below 17.5 K. Neutron
+scattering measurements indicate that the ordered moment is 0.03 $\mu_{B}$,
+much too small to account for the large heat capacity anomaly at 17.5 K. We
+present recent neutron scattering experiments which unveil a new piece of this
+puzzle - the spin excitation spectrum above 17.5 K exhibits well-correlated,
+itinerant-like spin excitations up to at least 10 meV emanating from
+incommensurate wavevectors. The gapping of these excitations corresponds to a
+large entropy release and explains the reduction in the electronic specific
+heat through the transition.",0710.0896v2
+2008-08-25,Low energy theory of the t-t'-t''-U Hubbard Model at half-filling: interaction strengths in cuprate superconductors and an effective spin-only description of La_2CuO_4,"Spin-only descriptions of the half-filled one-band Hubbard model are relevant
+for a wide range of Mott insulators. In addition to the usual Heisenberg
+exchange, many new types of interactions, including ring exchange, appear in
+the effective Hamiltonian in the intermediate coupling regime. In order to
+improve on the quantitative description of magnetic excitations in the
+insulating antiferromagnetic phase of copper-oxide (cuprate) materials, and to
+be consistent with band structure calculations and photoemission experiments on
+these systems, we include second and third neighbor hopping parameters, t' and
+t'', into the Hubbard Hamiltonian. A unitary transformation method is used to
+find systematically the effective Hamiltonian and any operator in the spin-only
+representation. The results include all closed, four hop electronic pathways in
+the canonical transformation. The method generates many ring exchange terms
+that play an important role in the comparison with experiments on La2CuO4.
+Performing a spin wave analysis, we calculate the magnon dispersion as a
+function of U,t,t' and t''. The four parameters are estimated by fitting the
+magnon dispersion to the experimental results of Coldea et al. [Phys. Rev.
+Lett. 86, 5377, {2001}] for La2CuO4. The ring exchange terms are found
+essential, in particular to determine the relative sign of t' and t'', with the
+values found in good agreement with independent theoretical and experimental
+estimates for other members of the cuprate family. The zero temperature
+sublattice magnetization is calculated using these parameters and also found to
+be in good agreement with the experimental value estimated by Lee et al. [Phys.
+Rev. B 60, 3643 (1999)]. We find a value of the interaction strength U~8t
+consistent with Mott insulating behavior.",0808.3167v1
+2010-05-31,The Effect of a Strong Stellar Flare on the Atmospheric Chemistry of an Earth-like Planet Orbiting an M dwarf,"Main sequence M stars pose an interesting problem for astrobiology: their
+abundance in our galaxy makes them likely targets in the hunt for habitable
+planets, but their strong chromospheric activity produces high energy radiation
+and charged particles that may be detrimental to life. We studied the impact of
+the 1985 April 12 flare from the M dwarf, AD Leonis (AD Leo), simulating the
+effects from both UV radiation and protons on the atmospheric chemistry of a
+hypothetical, Earth-like planet located within its habitable zone. Based on
+observations of solar proton events and the Neupert effect we estimated a
+proton flux associated with the flare of $5.9\times 10^{8}$ protons cm$^{-2}$
+sr$^{-1}$ s$^{-1}$ for particles with energies >10 MeV. Then we calculated the
+abundance of nitrogen oxides produced by the flare by scaling the production of
+these compounds during a large solar proton event called the ""Carrington
+event"". The simulations were performed using a 1-D photochemical model coupled
+to a 1-D radiative/convective model. Our results indicate that the ultraviolet
+radiation emitted during the flare does not produce a significant change in the
+ozone column depth of the planet. When the action of protons is included, the
+ozone depletion reached a maximum of 94% two years after the flare for a planet
+with no magnetic field. At the peak of the flare, the calculated UV fluxes that
+reach the surface, in the wavelength ranges that are damaging for life, exceed
+those received on Earth during less than 100 s. Flares may therefore not
+present a direct hazard for life on the surface of an orbiting habitable
+planet. Given that AD Leo is one of the most magnetically-active M dwarfs
+known, this conclusion should apply to planets around other M dwarfs with lower
+levels of chromospheric activity.",1006.0022v1
+2013-10-11,Neutron spectroscopic study of crystal field excitations in Tb2Ti2O7 and Tb2Sn2O7,"We present time-of-flight inelastic neutron scattering measurements at low
+temperature on powder samples of the magnetic pyrochlore oxides Tb2Ti2O7 and
+Tb2Sn2O7. These two materials possess related, but different ground states,
+with Tb2Sn2O7 displaying ""soft"" spin ice order below Tn~0.87 K, while Tb2Ti2O7
+enters a hybrid, glassy spin ice state below Tg~0.2 K. Our neutron
+measurements, performed at T=1.5 K and 30 K, probe the crystal field states
+associated with the J=6 states of Tb3+ within the appropriate Fd\bar{3}m
+pyrochlore environment. These crystal field states determine the size and
+anisotropy of the Tb3+ magnetic moment in each material's ground state,
+information that is an essential starting point for any description of the
+low-temperature phase behavior and spin dynamics in Tb2Ti2O7 and Tb2Sn2O7.
+While these two materials have much in common, the cubic stanate lattice is
+expanded compared to the cubic titanate lattice. As our measurements show, this
+translates into a factor of ~2 increase in the crystal field bandwidth of the
+2J+1=13 states in Tb2Ti2O7 compared with Tb2Sn2O7. Our results are consistent
+with previous measurements on crystal field states in Tb2Sn2O7, wherein the
+ground state doublet corresponds primarily to m_J=|\pm 5> and the first excited
+state doublet to mJ=|\pm 4>. In contrast, our results on Tb2Ti2O7 differ
+markedly from earlier studies, showing that the ground state doublet
+corresponds to a significant mixture of mJ=|\pm 5>, |\mp 4>, and |\pm 2>, while
+the first excited state doublet corresponds to a mixture of mJ=|\pm 4>, |\mp
+5>, and |\pm 1>. We discuss these results in the context of proposed mechanisms
+for the failure of Tb2Ti2O7 to develop conventional long-range order down to 50
+mK.",1310.3264v2
+2013-10-23,Functional Renormalization Group for multi-orbital Fermi Surface Instabilities,"Technological progress in material synthesis, as well as artificial
+realization of condensed matter scenarios via ultra-cold atomic gases in
+optical lattices or epitaxial growth of thin films, is opening the gate to
+investigate a plethora of unprecedented strongly correlated electron systems.
+In a large subclass thereof, a metallic state of layered electrons undergoes an
+ordering transition below some temperature into unconventional states of matter
+driven by electronic correlations, such as magnetism, superconductivity, or
+other Fermi surface instabilities. While this type of phenomena has been a
+well-established direction of research in condensed matter for decades, the
+variety of today's accessible scenarios pose fundamental new challenges to
+describe them. A core complication is the multi-orbital nature of the
+low-energy electronic structure of these systems, such as the multi-d orbital
+nature of electrons in iron pnictides and transition-metal oxides in general,
+but also electronic states of matter on lattices with multiple sites per unit
+cell such as the honeycomb or kagome lattice. In this review, we propagate the
+functional renormalization group (FRG) as a suited approach to investigate
+multi-orbital Fermi surface instabilities. The primary goal of the review is to
+describe the FRG in explicit detail and render it accessible to everyone both
+at a technical and intuitive level. Summarizing recent progress in the field of
+multi-orbital Fermi surface instabilities, we illustrate how the unbiased
+fashion by which the FRG treats all kinds of ordering tendencies guarantees an
+adequate description of electronic phase diagrams and often allows to obtain
+parameter trends of sufficient accuracy to make qualitative predictions for
+experiments. This review includes detailed and illustrative illustrations of
+magnetism and, in particular, superconductivity for the iron pnictides from the
+viewpoint of FRG. Furthermore, it discusses candidate scenarios for topological
+bulk singlet superconductivity and exotic particle-hole condensates on
+hexagonal lattices such as sodium-doped cobaltates, graphene doped to van Hove
+Filling, and the kagome Hubbard model. In total, the FRG promises to be one of
+the most versatile and revealing numerical approaches to address unconventional
+Fermi surface instabilities in future fields of condensed matter research.",1310.6191v1
+2014-09-10,"ARC: A compact, high-field, fusion nuclear science facility and demonstration power plant with demountable magnets","The affordable, robust, compact (ARC) reactor conceptual design study aims to
+reduce the size, cost, and complexity of a combined fusion nuclear science
+facility (FNSF) and demonstration fusion Pilot power plant. ARC is a 200-250
+MWe tokamak reactor with a major radius of 3.3 m, a minor radius of 1.1 m, and
+an on-axis magnetic field of 9.2 T. ARC has rare earth barium copper oxide
+(REBCO) superconducting toroidal field coils, which have joints to enable
+disassembly. This allows the vacuum vessel to be replaced quickly, mitigating
+first wall survivability concerns, and permits a single device to test many
+vacuum vessel designs and divertor materials. The design point has a plasma
+fusion gain of Q_p~13.6, yet is fully non-inductive, with a modest bootstrap
+fraction of only ~63%. Thus ARC offers a high power gain with relatively large
+external control of the current profile. This highly attractive combination is
+enabled by the ~23 T peak field on coil with newly available REBCO
+superconductor technology. External current drive is provided by two innovative
+inboard RF launchers using 25 MW of lower hybrid and 13.6 MW of ion cyclotron
+fast wave power. The resulting efficient current drive provides a robust,
+steady state core plasma far from disruptive limits. ARC uses an all-liquid
+blanket, consisting of low pressure, slowly flowing fluorine lithium beryllium
+(FLiBe) molten salt. The liquid blanket is low-risk technology and provides
+effective neutron moderation and shielding, excellent heat removal, and a
+tritium breeding ratio >= 1.1. The large temperature range over which FLiBe is
+liquid permits blanket operation at 900 K with single phase fluid cooling and a
+high-efficiency Brayton cycle, allowing for net electricity generation when
+operating ARC as a Pilot power plant.",1409.3540v2
+2016-01-20,The rate of quasiparticle recombination probes the onset of coherence in cuprate superconductors,"The condensation of an electron superfluid from a conventional metallic state
+at a critical temperature $T_c$ is described well by the BCS theory. In the
+underdoped copper-oxides, high-temperature superconductivity condenses instead
+from a nonconventional metallic ""pseudogap"" phase that exhibits a variety of
+non-Fermi liquid properties. Recently, it has become clear that a charge
+density wave (CDW) phase exists within the pseudogap regime, appearing at a
+temperature $T_{CDW}$ just above $T_c$. The near coincidence of $T_c$ and
+$T_{CDW}$, as well the coexistence and competition of CDW and superconducting
+order below $T_c$, suggests that they are intimately related. Here we show that
+the condensation of the superfluid from this unconventional precursor is
+reflected in deviations from the predictions of BSC theory regarding the
+recombination rate of quasiparticles. We report a detailed investigation of the
+quasiparticle (QP) recombination lifetime, $\tau_{qp}$, as a function of
+temperature and magnetic field in underdoped HgBa$_{2}$CuO$_{4+\delta}$
+(Hg-1201) and YBa$_{2}$Cu$_{3}$O$_{6+x}$ (YBCO) single crystals by ultrafast
+time-resolved reflectivity. We find that $\tau_{qp}(T)$ exhibits a local
+maximum in a small temperature window near $T_c$ that is prominent in
+underdoped samples with coexisting charge order and vanishes with application
+of a small magnetic field. We explain this unusual, non-BCS behavior by
+positing that $T_c$ marks a transition from phase-fluctuating SC/CDW composite
+order above to a SC/CDW condensate below. Our results suggest that the
+superfluid in underdoped cuprates is a condensate of coherently-mixed
+particle-particle and particle-hole pairs.",1601.05224v1
+2016-03-01,"Spin orientations of the spin-half Ir4+ ions in Sr3NiIrO6, Sr2IrO4 and Na2IrO3: Density functional, perturbation theory and Madelung potential analyses","The spins of the low-spin Ir4+ (S = 1/2, d5) ions at the octahedral sites of
+the oxides Sr3NiIrO6, Sr2IrO4 and Na2IrO3 exhibit preferred orientations with
+respect to their IrO6 octahedra. We evaluated the magnetic anisotropies of
+these S = 1/2 ions on the basis of DFT calculations including spin-orbit
+coupling (SOC), and probed their origin by performing perturbation theory
+analyses with SOC as perturbation within the LS coupling scheme. The observed
+spin orientations of Sr3NiIrO6 and Sr2IrO4 are correctly predicted by DFT
+calculations, and are accounted for by the perturbation theory analysis. As for
+the spin orientation of Na2IrO3, both experimental studies and DFT calculations
+have not been unequivocal. Our analysis reveals that the Ir4+ spin orientation
+of Na2IrO3 should have nonzero components along the c- and a-axes directions.
+The spin orientations determined by DFT calculations are sensitive to the
+accuracy of the crystal structures employed, which is explained by perturbation
+theory analyses when interactions between adjacent Ir4+ ions are taken into
+consideration. There are indications implying that the 5d electrons of Na2IrO3
+are less strongly localized compared with those of Sr3NiIrO6 and Sr2IrO4. This
+implication was confirmed by showing that the Madelung potentials of the Ir4+
+ions are less negative in Na2IrO3 than in Sr3NiIrO6, Sr2IrO4. Most
+transition-metal S = 1/2 ions do have magnetic anisotropies because the SOC
+induces interactions among their crystal-field split d-states, and the
+associated mixing of the states modifies only the orbital parts of the states.
+This finding cannot be mimicked by a spin Hamiltonian because this model
+Hamiltonian lacks the orbital degree of freedom, thereby leading to the
+spin-half syndrome. The spin-orbital entanglement for the 5d spin-half ions
+Ir4+ is not as strong as has been assumed lately.",1603.00523v2
+2016-04-28,"Highly-anisotropic exchange interactions of $j_{\rm eff}=1/2$ iridium moments on the fcc lattice in La$_2B$IrO$_6$ ($B$ $=$ Mg, Zn)","We have performed inelastic neutron scattering (INS) experiments to
+investigate the magnetic excitations in the weakly distorted
+face-centered-cubic (fcc) iridate double perovskites La$_2$ZnIrO$_6$ and
+La$_2$MgIrO$_6$, which are characterized by A-type antiferromagnetic ground
+states. The powder inelastic neutron scattering data on these geometrically
+frustrated $j_{\rm eff}=1/2$ Mott insulators provide clear evidence for gapped
+spin wave excitations with very weak dispersion. The INS results and
+thermodynamic data on these materials can be reproduced by conventional
+Heisenberg-Ising models with significant uniaxial Ising anisotropy and sizeable
+second-neighbor ferromagnetic interactions. Such a uniaxial Ising exchange
+interaction is symmetry-forbidden on the ideal fcc lattice, so that it can only
+arise from the weak crystal distortions away from the ideal fcc limit. This may
+suggest that even weak distortions in $j_{\rm eff}=1/2$ Mott insulators might
+lead to strong exchange anisotropies. More tantalizingly, however, we find an
+alternative viable explanation of the INS results in terms of spin models with
+a dominant Kitaev interaction. In contrast to the uniaxial Ising exchange, the
+highly-directional Kitaev interaction is a type of exchange anisotropy which is
+symmetry-allowed even on the ideal fcc lattice. The Kitaev model has a magnon
+gap induced by quantum order-by-disorder, while weak anisotropies of the Kitaev
+couplings generated by the symmetry-lowering due to lattice distortions, can
+pin the order and enhance the magnon gap. Our findings highlight how even
+conventional magnetic orders in heavy transition metal oxides may be driven by
+highly-directional exchange interactions rooted in strong spin-orbit coupling.",1604.08431v1
+2011-11-24,Modern trends in Superconductivity and Superfluidity. Selected Chapters,"In Chapter 1 we start with general Landau scheme of the conservation laws for
+the hydrodynamics of classical liquids and superfluids. On the basis of Landau
+scheme we consider hydrodynamics of rotating superfluids with large number of
+vortices. We study different regimes of slow and fast rotations. In Chapter 4
+we consider complicated and yet unresolved problem of chiral anomaly in
+superfluid 3He-A and present two competing approaches. The first one is based
+on supersymmetric hydrodynamics, another one on the formal analogy with Dirac
+equation in QED. In Chapters 6 and 7 we study composed fermions and bosons
+which correspond to the different bound states consisting of two fermions, two
+bosons and fermion and boson in ultracold quantum gasses and mixtures. We also
+elucidate the exact solutions of the Skorniakov-Ter-Martirosian integral
+equations. We present the basic ideas of Nozieres-Schmitt Rink and Legget
+theory on BCS-BEC crossover in quantum gasses and construct the phase diagrams
+for the s-wave and p-wave pairings. In Chapters 9 and 10 we discuss non-phonon
+mechanisms of superconductivity of the Kohn-Luttinger type for different models
+in 3D and 2D electron systems at low densities including Fermi-gas, Hubbard and
+Shubin-Vonsovsky models. We complete the superconductive phase-diagrams of
+p-wave and d-wave pairing and discuss the possibility to increase Tc already at
+low density. In Chapters 15 and 16 the mechanisms of electron nanoscale
+phase-separation in manganite-type oxide materials are analyzed. The
+instability of magnetic (or charge) homogeneous ordering towards the formation
+of droplet structures (magnetic polarons) is predicted for a wide parameter
+range on the phase-diagram. The transport properties of these materials in the
+phase-separated state are also discussed.",1111.5711v5
+2015-12-07,Recent progress on correlated electron systems with strong spin-orbit coupling,"Emergence of novel quantum ground states in correlated electron systems with
+strong spin-orbit coupling has been a recent subject of intensive studies.
+While it has been realized that spin-orbit coupling can provide non-trivial
+band topology in weakly interacting electron systems, as in topological
+insulators and semi-metals, the role of electron-electron interaction in
+strongly spin-orbit coupled systems has not been fully understood. The
+availability of new materials with significant electron correlation and strong
+spin-orbit coupling now makes such investigations possible. Many of these
+materials contain 5d or 4d transition metal elements; the prominent examples
+are iridium oxides or iridates. In this review, we succinctly discuss recent
+theoretical and experimental progress on this subject. After providing a brief
+overview, we focus on pyrochlore iridates and three-dimensional honeycomb
+iridates. In pyrochlore iridates, we discuss the quantum criticality of the
+bulk and surface states, and the relevance of the surface/boundary states in a
+number of topological and magnetic ground states, both in the bulk and thin
+film configurations. Experimental signatures of these boundary and bulk states
+are discussed. Domain wall formation and strongly-direction-dependent
+magneto-transport are also discussed. Regarding the three-dimensional honeycomb
+iridates, we consider possible quantum spin liquid phases and unusual magnetic
+orders in theoretical models with strongly bond-dependent interactions. These
+theoretical ideas and results are discussed in light of recent resonant X-ray
+scattering experiments on three-dimensional honeycomb iridates. We also
+contrast these results with the situation in two-dimensional honeycomb
+iridates. We conclude with the outlook on other related systems.",1512.02224v1
+2016-12-16,Experimental verification of orbital engineering at the atomic scale: charge transfer and symmetry breaking in nickelate heterostructures,"Epitaxial strain, layer confinement and inversion symmetry breaking have
+emerged as powerful new approaches to control the electronic and atomic-scale
+structural properties in complex metal oxides. Nickelate heterostructures,
+based on RENiO$_3$, where RE is a trivalent rare-earth cation, have been shown
+to be relevant model systems since the orbital occupancy, degeneracy, and,
+consequently, the electronic/magnetic properties can be altered as a function
+of epitaxial strain, layer thickness and superlattice structure. One such
+recent example is the tri-component LaTiO$_3$-LaNiO$_3$-LaAlO$_3$ superlattice,
+which exhibits charge transfer and orbital polarization as the result of its
+interfacial dipole electric field. A crucial step towards control of these
+parameters for future electronic and magnetic device applications is to develop
+an understanding of both the magnitude and range of the octahedral network's
+response towards interfacial strain and electric fields. An approach that
+provides atomic-scale resolution and sensitivity towards the local octahedral
+distortions and orbital occupancy is therefore required. Here, we employ
+atomic-resolution imaging coupled with electron spectroscopies and first
+principles theory to examine the role of interfacial charge transfer and
+symmetry breaking in a tricomponent nickelate superlattice system. We find that
+nearly complete charge transfer occurs between the LaTiO$_3$ and LaNiO$_3$
+layers, resulting in a Ni$^{2+}$ valence state. We further demonstrate that
+this charge transfer is highly localized with a range of about 1 unit cell,
+within the LaNiO$_3$ layers. The results presented here provide important
+feedback to synthesis efforts aimed at stabilizing new electronic phases that
+are not accessible by conventional bulk or epitaxial film approaches.",1612.05610v1
+2017-07-13,Probing low noise at the MOS interface with a spin-orbit qubit,"The silicon metal-oxide-semiconductor (MOS) material system is
+technologically important for the implementation of electron spin-based quantum
+information technologies. Researchers predict the need for an integrated
+platform in order to implement useful computation, and decades of advancements
+in silicon microelectronics fabrication lends itself to this challenge.
+However, fundamental concerns have been raised about the MOS interface (e.g.
+trap noise, variations in electron g-factor and practical implementation of
+multi-QDs). Furthermore, two-axis control of silicon qubits has, to date,
+required the integration of non-ideal components (e.g. microwave strip-lines,
+micro-magnets, triple quantum dots, or introduction of donor atoms). In this
+paper, we introduce a spin-orbit (SO) driven singlet-triplet (ST) qubit in
+silicon, demonstrating all-electrical two-axis control that requires no
+additional integrated elements and exhibits charge noise properties equivalent
+to other more model, but less commercially mature, semiconductor systems. We
+demonstrate the ability to tune an intrinsic spin-orbit interface effect, which
+is consistent with Rashba and Dresselhaus contributions that are remarkably
+strong for a low spin-orbit material such as silicon. The qubit maintains the
+advantages of using isotopically enriched silicon for producing a quiet
+magnetic environment, measuring spin dephasing times of 1.6 $\mu$s using 99.95%
+$^{28}$Si epitaxy for the qubit, comparable to results from other isotopically
+enhanced silicon ST qubit systems. This work, therefore, demonstrates that the
+interface inherently provides properties for two-axis control, and the
+technologically important MOS interface does not add additional detrimental
+qubit noise.",1707.04357v1
+2020-01-22,Superconductivity by Hidden Spin Fluctuations in Electron-Doped Iron Selenide,"Berg, Metlitski and Sachdev, Science 338, 1606 (2012), have shown that the
+exchange of hidden spin fluctuations by conduction electrons with two orbitals
+can result in high-temperature superconductivity in copper-oxide materials. We
+introduce a similar model for high-temperature iron-selenide superconductors
+that are electron doped. Conduction electrons carry the minimal 3d xz and 3d yz
+iron-atom orbitals. Low-energy hidden spin fluctuations at the checkerboard
+wavevector Q_AF result from nested Fermi surfaces at the center and at the
+corner of the unfolded (one-iron) Brillouin zone. Magnetic frustration from
+super-exchange interactions via the selenium atoms stabilize hidden spin
+fluctuations at Q_AF versus true spin fluctuations. At half filling, Eliashberg
+theory based purely on the exchange of hidden spin fluctuations reveals a
+Lifshitz transition to electron/hole Fermi surface pockets at the corner of the
+folded (two-iron) Brillouin zone, but with vanishing spectral weights. The
+underlying hidden spin-density wave groundstate is therefore a Mott insulator.
+Upon electron doping, Eliashberg theory finds that the spectral weights of the
+hole Fermi surface pockets remain vanishingly small, while the spectral weights
+of the larger electron Fermi surface pockets become appreciable. This
+prediction is therefore consistent with the observation of electron Fermi
+surface pockets alone in electron-doped iron selenide by angle-resolved
+photoemission spectroscopy (ARPES). Eliashberg theory also finds an instability
+to S+- superconductivity at electron doping, with isotropic Cooper pairs that
+alternate in sign between the visible electron Fermi surface pockets and the
+faint hole Fermi surface pockets. Comparison with the isotropic energy gaps
+observed in electron-doped iron selenide by ARPES and by scanning tunneling
+microscopy (STM) is consistent with short-range hidden magnetic order.",2001.07908v3
+2020-12-28,"Structural, optical and magnetic properties of nanostructured Cr-substituted Ni-Zn spinel ferrites synthesized by a microwave combustion method","Nanoparticles of Cr3+-substituted Ni-Zn ferrites with a general formula
+Ni0.4Zn0.6-xCrxFe2O4 (x = 0.0 - 0.6) have been synthesized via a facile
+microwave combustion route. The crystalline phase has been characterized by
+XRD, TEM, FT-I and XPS revealing the spinel ferrite structure without extra
+phases. Crystallite sizes of 23 - 32 nm as estimated by XRD analyses, after
+corrections for crystal stains by Williamson-Hall method, are comparable to the
+average particle sizes observed by TEM which indicates successfully synthesized
+nanocrystals. Rietveld refinement analyses of the XRD patterns have inferred a
+monotonic decrease behavior of the lattice parameter with Cr doping in
+agreement with Vegard's law of solid solution series. Furthermore, cations
+distribution with an increased inversion factor indicate the B-site preference
+of Cr3+ ions. The oxidation states and cations distribution indicated by XPS
+results imply the Cr3+ doping on the account of Zn2+ ions and a partial
+reduction of Fe3+ to Fe2+ to keep the charge balance in a composition series of
+(Ni2+)0.4(Zn2+, Cr3+)0.6(Fe2+, Fe3+)2(O2-)4. The optical properties were
+explored by optical UV-Vis spectroscopy indicating allowed direct transitions
+with band gap energy that decreases from 3.9 eV to 3.7 eV with Cr doping.
+Furthermore, the photocatalytic activity for the degradation of methyl orange
+(MO) dye was investigated showing largely enhanced photodecomposition up to 30%
+of MO dye over Ni0.4Cr0.6Fe2O4 for 6 hours. A vibrating sample magnetometry
+(VSM) measurements at room temperature show further enhancement in the
+saturation magnetization of Ni0.4Zn0.6Fe2O4 , the highest in Ni-Zn ferrites,
+from about 60 to 70 emu/g with the increase of Cr concentration up to x = 0.1,
+while the coercivity shows a general increase in the whole range of Cr doping.",2012.14232v1
+2019-01-15,Ferromagnetic Epitaxial μ-Fe$_{2}$O$_{3}$ on β-Ga$_{2}$O$_{3}$: A New Monoclinic form of Fe$_{2}$O$_{3}$,"Here we demonstrate a new monoclinic iron oxide phase
+({\mu}-Fe$_{2}$O$_{3}$), epitaxially stabilized by growth on (010)
+{\beta}-Ga$_{2}$O$_{3}$. Density functional theory (DFT) calculations find that
+the lattice parameters of freestanding {\mu}-Fe$_{2}$O$_{3}$ are within ~1% of
+those of {\beta}-Ga$_{2}$O$_{3}$ and that its energy of formation is comparable
+to that of naturally abundant Fe$_{2}$O$_{3}$ polytypes. A superlattice of
+{\mu}-Fe$_{2}$O$_{3}$/{\beta}-Ga$_{2}$O$_{3}$ is grown by plasma assisted
+molecular beam epitaxy, with resulting high-resolution x-ray diffraction (XRD)
+measurements indicating that the {\mu}-Fe$_{2}$O$_{3}$ layers are
+lattice-matched to the substrate. The measured out-of-plane (b) lattice
+parameter of 3.12 $\pm$ 0.4 {\AA} is in agreement with the predicted lattice
+constants and atomic-resolution scanning transmission electron microscopy
+(STEM) images confirm complete registry of the {\mu}-Fe$_{2}$O$_{3}$ layers
+with {\beta}-Ga$_{2}$O$_{3}$. Finally, DFT modeling predicts that bulk
+{\mu}-Fe$_{2}$O$_{3}$ is antiferromagnetic, while the interface region between
+{\mu}-Fe$_{2}$O$_{3}$ and {\beta}-Ga$_{2}$O$_{3}$ leads to ferromagnetic
+coupling between interface Fe$^{3+}$ cations selectively occupying tetrahedral
+positions. Magnetic hysteresis persisting to room temperature is observed via
+SQUID measurements, consistent with the computationally predicted interface
+magnetism.",1901.04844v2
+2020-09-25,Strain-engineering of the charge and spin-orbital interactions in Sr2IrO4,"In the high spin-orbit coupled Sr2IrO4, the high sensitivity of the ground
+state to the details of the local lattice structure shows a large potential for
+the manipulation of the functional properties by inducing local lattice
+distortions. We use epitaxial strain to modify the Ir-O bond geometry in
+Sr2IrO4 and perform momentum-dependent Resonant Inelastic X-ray Scattering
+(RIXS) at the metal and at the ligand sites to unveil the response of the low
+energy elementary excitations. We observe that the pseudospin-wave dispersion
+for tensile-strained Sr2IrO4 films displays large softening along the [h,0]
+direction, while along the [h,h] direction it shows hardening. This evolution
+reveals a renormalization of the magnetic interactions caused by a
+strain-driven crossover from anisotropic to isotropic interactions between the
+magnetic moments. Moreover, we detect dispersive electron-hole pair excitations
+which shift to lower (higher) energies upon compressive (tensile) strain,
+manifesting a reduction (increase) in the size of the charge gap. This behavior
+shows an intimate coupling between charge excitations and lattice distortions
+in Sr2IrO4, originating from the modified hopping elements between the t2g
+orbitals. Our work highlights the central role played by the lattice degrees of
+freedom in determining both the pseudospin and charge excitations of Sr2IrO4
+and provides valuable information towards the control of the ground state of
+complex oxides in the presence of high spin-orbit coupling.",2009.12262v1
+2020-10-22,"Synthesis and physical properties of perovskite Sm$_{1-x}$Sr$_x$NiO$_3$ (x = 0, 0.2) and infinite-layer Sm$_{0.8}$Sr$_{0.2}$NiO$_2$ nickelates","Recently, superconductivity at about 9-15K was discovered in
+Nd$_{1-x}$Sr$_x$NiO$_2$ infinite-layer thin films, which has stimulated
+enormous interests in related rare-earth nickelates. Usually, the first step to
+synthesize this 112 phase is to fabricate the RNiO$_3$ phase, however, it was
+reported that the 113 phase is very difficult to be synthesized successfully
+due to the formation of unusual Ni$^{3+}$ oxidation state. And the difficulty
+of preparation is enhanced as the ionic radius of rare-earth element decreases.
+In this work, we report the synthesis and investigation on multiple physical
+properties of polycrystalline perovskites Sm$_{1-x}$Sr$_x$NiO$_3$ (x = 0, 0.2)
+in which the ionic radius of Sm$^{3+}$ is smaller than that of Pr$^{3+}$ and
+Nd$^{3+}$ in related superconducting thin films. The structural and
+compositional analyses conducted by X-ray diffraction and energy dispersive
+X-ray spectrum reveal that the samples mainly contain the perovskite phase of
+Sm$_{1-x}$Sr$_x$NiO$_3$ with small amount of NiO impurities. Magnetization and
+resistivity measurements indicate that the parent phase SmNiO$_3$ undergoes a
+paramagnetic-antiferromagnetic transition at about 224K on a global insulating
+background. In contrast, the Sr-doped sample Sm$_{0.8}$Sr$_{0.2}$NiO$_3$ shows
+a metallic behavior from 300K down to about 12K, while below 12K the
+resistivity exhibits a slight logarithmic increase. Meanwhile, from the
+magnetization curves, we can see that a possible spin-glass state occurs below
+12K in Sm$_{0.8}$Sr$_{0.2}$NiO$_3$. Using a soft chemical reduction method, we
+also obtain the infinite-layer phase Sm$_{0.8}$Sr$_{0.2}$NiO$_2$ with square
+NiO$_2$ planes. The compound shows an insulating behavior which can be
+described by the three-dimensional variable-range-hopping model. And
+superconductivity is still absent in the polycrystalline
+Sm$_{0.8}$Sr$_{0.2}$NiO$_2$.",2010.11777v2
+2022-02-16,Giant oscillatory tunnel magnetoresistance in CoFe/MgO/CoFe(001) junctions,"The tunnel magnetoresistance (TMR) effect observed in magnetic tunnel
+junctions (MTJs) is commonly used in many spintronic applications because the
+effect can easily convert from local magnetic states to electric signals in a
+wide range of device resistances. In this study, we demonstrated TMR ratios of
+up to 631% at room temperature (RT), which is two or more times larger than
+those used currently for magnetoresistive random access memory (MRAM) devices,
+using CoFe/MgO/CoFe(001) epitaxial MTJs. The TMR ratio increased up to 1143% at
+10 K, which corresponds to an effective tunneling spin polarization of 0.923.
+The observed large TMR ratios resulted from the fine-tuning of atomic-scale
+structures of the MTJs, such as crystallographic orientations and MgO interface
+oxidation, in which the well-known Delta1 coherent tunneling mechanism for the
+giant TMR effect is expected to be pronounced. However, behavior that is not
+covered by the standard coherent tunneling theory was unexpectedly manifested;
+i.e., (i) TMR saturation at a thick MgO barrier region and (ii) enhanced TMR
+oscillation with a 0.32 nm period in MgO thickness. Particularly, the TMR
+oscillatory behavior dominates the transport in a wide range of MgO
+thicknesses; the peak-to-valley difference of the TMR oscillation exceeded 140%
+at RT, attributable to the appearance of large oscillatory components in
+resistance area product (RA). Further, we found that the oscillatory behaviors
+of the TMR ratio and RA survive, even under a +-1 V bias voltage application,
+indicating the robustness of the oscillation. Our demonstration of the giant
+RT-TMR ratio will be an essential step for establishing spintronic
+architectures, such as large-capacity MRAMs and spintronic artificial neural
+networks. More essentially, the present observations can trigger us to revisit
+the true TMR mechanism in crystalline MTJs.",2202.07847v1
+2022-04-06,First principles investigation of anionic redox in bisulfate lithium battery cathodes,"The search for an alternative high-voltage polyanionic cathode material for
+Li-ion batteries is vital to improve the energy densities beyond the
+state-of-the-art, where sulfate frameworks form an important class of
+high-voltage cathode materials due to the strong inductive effect of the
+S$^{6+}$ ion. Here, we have investigated the mechanism of cationic and/or
+anionic redox in Li$_x$M(SO$_4$)$_2$ frameworks (M = Mn, Fe, Co, and Ni and 0
+$\leq$ x $\leq$ 2) using density functional calculations. Specifically, we have
+used a combination of Hubbard $U$ corrected strongly constrained and
+appropriately normed (SCAN+$U$) and generalized gradient approximation
+(GGA+$U$) functionals to explore the thermodynamic (polymorph stability),
+electrochemical (intercalation voltage), geometric (bond lengths), and
+electronic (band gaps, magnetic moments, charge populations, etc.) properties
+of the bisulfate frameworks considered. Importantly, we find that the anionic
+(cationic) redox process is dominant throughout delithiation in the Ni (Mn)
+bisulfate, as verified using our calculated projected density of states, bond
+lengths, and on-site magnetic moments. On the other hand, in Fe and Co
+bisulfates, cationic redox dominates the initial delithiation (1 $\leq$ x
+$\leq$ 2), while anionic redox dominates subsequent delithiation (0 $\leq$ x
+$\leq$ 2). In addition, evaluation of the crystal overlap Hamilton population
+reveals insignificant bonding between oxidizing O atoms throughout the
+delithiation process in the Ni bisulfate, indicating robust battery performance
+that is resistant to irreversible oxygen evolution. Finally, we observe both
+GGA+$U$ and SCAN+$U$ predictions are in qualitative agreement for the various
+properties predicted. Our work should open new avenues for exploring lattice
+oxygen redox in novel high voltage polyanionic cathodes, especially using the
+SCAN+$U$ functional.",2204.02673v1
+2022-06-22,Oxygen vacancy formation and electronic reconstruction in strained LaNiO$_3$ and LaNiO$_3$/LaAlO$_3$ superlattices,"By using DFT+U, we explore the formation of oxygen vacancies and their impact
+on the electronic and magnetic structure in strained bulk LaNiO3 and
+(LaNiO3)$_1$/(LaAlO3)$_1$(001) superlattices. For bulk LaNiO3, we find that
+epitaxial strain induces a substantial anisotropy in the oxygen vacancy
+formation energy. In particular, tensile strain promotes the selective
+reduction of apical oxygen, which may explain why the recently observed
+superconductivity of infinite-layer nickelates is limited to strained films.
+For (LaNiO3)$_1$/(LaAlO3)$_1$(001) superlattices, the simulations reveal that
+the NiO2 layer is most prone to vacancy formation, whereas the AlO2 layer
+exhibits generally the highest formation energies. The reduction is
+consistently endothermic, and a largely repulsive vacancy-vacancy interaction
+is identified as a function of the vacancy concentration. The released
+electrons are accommodated exclusively in the NiO2 layer, reducing the vacancy
+formation energy in the AlO2 layer by 70% with respect to bulk LaAlO3. By
+varying the vacancy concentration from 0% to 8.3% in the NiO2 layer at tensile
+strain, we observe an unexpected transition from a localized
+site-disproportionated (0.5%) to a delocalized (2.1%) charge accommodation, a
+re-entrant site disproportionation leading to a metal-to-insulator transition
+despite a half-filled majority-spin Ni $e_g$ manifold (4.2%), and finally a
+magnetic phase transition (8.3%). While a band gap of up to 0.5 eV opens at
+4.2% for compressive strain, it is smaller for tensile strain or the system is
+metallic, which is in sharp contrast to the defect-free superlattice. The
+strong interplay of electronic reconstructions and structural modifications
+induced by oxygen vacancies in this system highlights the key role of an
+explicit supercell treatment and exemplifies the complex response to defects in
+artificial transition metal oxides.",2206.11028v1
+2023-06-29,Optimization strategies developed on NiO for Heisenberg exchange coupling calculations using projector augmented wave based first-principles DFT+U+J,"High-performance batteries, heterogeneous catalysts and next-generation
+photovoltaics often centrally involve transition metal oxides (TMOs) that
+undergo charge or spin-state changes. Demand for accurate DFT modeling of TMOs
+has increased in recent years, driving improved quantification and correction
+schemes for approximate DFT's characteristic errors, notably those pertaining
+to self-interaction and static correlation. Of considerable interest,
+meanwhile, is the use of DFT-accessible quantities to compute parameters of
+coarse-grained models such as for magnetism. To understand the interference of
+error corrections and model mappings, we probe the prototypical Mott-Hubbard
+insulator NiO, calculating its electronic structure in its antiferromagnetic
+I/II and ferromagnetic states. We examine the pronounced sensitivity of the
+first principles calculated Hubbard U and Hund's J parameters to choices
+concerning Projector Augmented Wave (PAW) based population analysis, we
+reevaluate spin quantification conventions for the Heisenberg model, and we
+seek to develop best practices for calculating Hubbard parameters specific to
+energetically meta-stable magnetic orderings of TMOs. Within this framework, we
+assess several corrective functionals using in situ calculated U and J
+parameters, e.g., DFT+U and DFT+U+J. We find that while using a straightforward
+workflow with minimal empiricism, the NiO Heisenberg parameter RMS error with
+respect to experiment was reduced to 13%, an advance upon the state-of-the-art.
+Methodologically, we used a linear-response implementation for calculating the
+Hubbard U available in the open-source plane-wave DFT code Abinit. We have
+extended its utility to calculate the Hund's exchange coupling J, however our
+findings are anticipated to be applicable to any DFT+U implementation.",2306.17148v2
+2024-03-24,The nontrivial effects of annealing on superconducting properties of Nb single crystals,"The effect of annealing on the superconducting properties of niobium single
+crystals cut from the same master boule was studied by local and global
+magnetic measurements, as well as scanning tunneling microscopy (STM). The
+formation of large hydride precipitates was observed in unannealed samples. The
+variation in structural and magnetic properties was studied after annealing
+under high vacuum at 800 C, 1400 C, and near the melting point of niobium (2477
+C) for a few seconds. The initial samples had a high hydrogen content.
+Polarized optics and magneto-optical studies show that the formation of large
+niobium hydride precipitates is suppressed already by 800 C annealing. However,
+the overall superconducting properties in the annealed samples did not improve
+after annealing, and in fact, worsened. The superconducting transition
+temperature decreased, the upper critical field increased, and the pinning
+strength increased. Parallel studies were conducted using STM, where the sample
+was annealed initially at 400 C, measured, annealed again at 1700 C, and
+measured again. These studies revealed a ``dirty'' superconducting gap with a
+significant spatial variation of tunneling conductance after annealing at 400
+C. The clean gap was recovered after annealing at 1700 C. It is likely that
+these results are due to oxygen redistribution near the surface, which is
+always covered by oxide layers in as-grown crystals. Overall, the results
+indicate that vacuum annealing at least up to 1400 C, while expected to remove
+a large amount of hydrogen, introduces additional nanosized defects, perhaps
+hydride precipitates, that act as efficient pair-breaking and pinning centers.",2403.16279v1
+1995-11-08,On the Stereochemistry of the Cations in the Doping Block of Superconducting Copper-Oxides,"Metal-oxygen complexes containing Cu,- Tl-, Hg-, Bi- and Pb-cations are
+electronically active in superconducting copper-oxides by stabilizing single
+phases with enhanced $T_c$, whereas other metal-oxygen complexes deteriorate
+copper-oxide superconductivity. Cu, Tl, Hg, Bi, Pb in their actual oxidation
+states are closed shell $d^{10}$ or inert $s^2$ pair ions. Their electronic
+configurations have a strong tendency to polarize the oxygen environment. The
+closed shell $d$ ions with low lying $nd^{10}\leftrightarrow nd^9(n+1)s$
+excitations form linear complexes through $d_{z^2}-s$ hybridization polarizing
+the apical oxygens. Comparatively low $nd^9(n+1)s$ excitation energies
+distinguish $\rm Cu^{1+,3+}, Tl^{3+}, Hg^{2+}$ from other closed shell $d^{10}$
+ions deteriorating copper-oxide superconductivity, {\it e.g.} $\rm Zn^{2+}$.",9511041v2
+1999-01-28,Diffusion-reaction in thermal growth of silicon oxide films on Si,"The thermal growth of silicon oxide films on Si in dry O2 is modelled as a
+dynamical system, assuming that it is basically a diffusion-reaction
+phenomenon. Relevant findings of the last decade are incorporated, as structure
+and composition of the oxide/Si interface and O2 transport and reaction at
+initial stages of growth. The present model departs from the well established
+Deal and Grove framework (Deal, B.E. and Grove, A. S. General Relationship for
+the Thermal Oxidation of Silicon, J. Appl. Phys. 36, 3770-3778 (1965))
+indicating that its basic assumptions, steady-state regime and reaction between
+O2 and Si at a sharp oxide/Si interface are only attained asymptotically.
+Experimental growth kinetics by various authors, obtained for a wide range of
+growth parameters are shown to collapse into one single curve when the scaling
+properties of this model equations are explored.",9901335v1
+2005-07-01,Silver-assisted growth of NdBa2Cu3O7-d thin films: A novel approach for the growth of superior quality ceramic oxide films,"We have grown NdBa2Cu3O7-d films under silver atomic flux by molecular beam
+epitaxy, which show a drastic improvement in microstructure and also
+crystallinity leading to 30 % enhancement in critical current density. The most
+remarkable point is that the final film is free from silver. The key to our
+process in achieving a silver-free film was the use of RF-activated oxygen that
+oxidizes silver, nonvolatile, to silver oxide, volatile at the deposition
+temperature. This process enables one to utilize the beneficial effects of
+silver in the growth of oxide films and at the same time ensures that the final
+film be free from silver, which is important for high-frequency applications.
+This method can be made use in the growth of thin films of other complex oxide
+materials.",0507006v1
+2005-08-16,Low frequency noise statistics for the breakdown characterization of ultra-thin gate oxides,"We have investigated the statistics of low frequency noise in the tunneling
+current of ultrathin oxides (2.5nm-4nm) in metal oxide semiconductor capacitors
+as a function of the applied voltage stress. The statistical analysis includes
+(i) non-Gaussianity (nG), which is a measure of the degree of temporal
+correlation in the noise, and (ii) ratio of integrated noise power to the DC
+leakage current (R). The occurrence of high peaks in nG indicates the
+appearance of new percolation paths, and the subsequent conduction through
+these paths is indicated by R. Our results show that the nG and R
+characteristics are generic for the oxides of different thickness and growth
+quality and have the potential, in conjunction with leakage itself, of being
+used as a prognosticator of oxide reliability.",0508370v1
+2006-09-05,First-principles statistical mechanics study of the stability of a sub-nanometer thin surface oxide in reactive environments: CO oxidation at Pd(100),"We employ a multiscale modeling approach to study the surface structure and
+composition of a Pd(100) model catalyst in reactive environments. Under gas
+phase conditions representative of technological CO oxidation (~1 atm, 300-600
+K) we find the system on the verge of either stabilizing sub-nanometer thin
+oxide structures or CO adlayers at the surface. Under steady-state operation
+this suggests the presence or continuous formation and reduction of oxidic
+patches at the surface, which could be key to understand the observable
+catalytic function.",0609083v1
+2006-12-04,Superconductivity and Disorder in High-Tc Materials: Crystalline Copper Oxides and Liquid Metallic Hydrogen,"Our goals are to assist a non-practitioner understand likely resolution of
+the controversy about the boson that couples Cooper pairs in Cu oxides and to
+consider if high temperature superconductivity (HTS) in solid oxides might be
+related to predicted HTS in liquid metallic hydrogen (LMH) near 0 K. High
+temperatures (T~Tc~!D~100 K, where Tc is superconducting critical temperature
+and !D is the Debye temperature) induce phonon-phonon scattering in ordered
+materials, which is sensitive to impurities and disorder. Experimental results
+suggest the boson that couples Cooper pairs in Bi2SrCa2Cu2O8 is incoherent ion
+vibration caused by disorder, which is observed from ~100 K down to 4 K.
+Phonons are not well-defined in BSSCO and its coherence length is comparable to
+the dimension of its unit cell (~1 nm), as for other oxides. Sr2CuO3+d (Tc=95
+K) has a crystal structure that enables experimental demonstration that
+disorder of apical oxygen atoms has a strong affect on Tc. Disorder in sold
+oxides on an atomic scale and the temperature dependence of phonons at high
+temperatures (T~!D) probably must be taken into account to understand HTS.
+There are several reasons to believe that LMH will be a high temperature
+superconductor and no known reason why LMH cannot be one.",0612069v1
+2002-12-03,The group theory of oxidation II: Cosets of non-split groups,"The oxidation program of hep-th/0210178 is extended to cover oxidation of 3-d
+sigma model theories on a coset G/H, with G non-compact (but not necessarily
+split), and H the maximal compact subgroup. We recover the matter content, the
+equations of motion and Bianchi identities from group lattice and Cartan
+involution. Satake diagrams provide an elegant tool for the computations, the
+maximal oxidation dimension, and group disintegration chains can be directly
+read off. We give a complete list of theories that can be recovered from
+oxidation of a 3 dimensional coset sigma model on G/H, where G is a simple
+non-compact group.",0212024v2
+2007-07-13,Ultrathin oxides: bulk-oxide-like model surfaces or unique films?,"To better understand the electronic and chemical properties of wide-gap oxide
+surfaces at the atomic scale, experimental work has focused on epitaxial films
+on metal substrates. Recent findings show that these films are considerably
+thinner than previously thought. This raises doubts about the transferability
+of the results to surface properties of thicker films and bulk crystals. By
+means of density-functional theory and approximate GW corrections for the
+electronic spectra we demonstrate for three characteristic wide-gap oxides
+(silica, alumina, and hafnia) the influence of the substrate and highlight
+critical differences between the ultrathin films and surfaces of bulk
+materials. Our results imply that monolayer-thin oxide films have rather unique
+properties.",0707.2031v1
+2007-10-03,The effect of ozone oxidation on single-walled carbon nanotubes,"Exposing single-walled carbon nanotubes to room temperature UV-generated
+ozone leads to an irreversible increase in their electrical resistance. We
+demonstrate that the increased resistance is due to ozone oxidation on the
+sidewalls of the nanotubes rather than at the end caps. Raman and x-ray
+photoelectron spectroscopy show an increase in the defect density due to the
+oxidation of the nanotubes. Using ultraviolet photoelectron spectroscopy we
+show that these defects represent the removal of pi-conjugated electron states
+near the Fermi level, leading to the observed increase in electrical
+resistance. Oxidation of carbon nanotubes is an important first step in many
+chemical functionalization processes. Since the oxidation rate is controllable
+with short exposures, UV-generated ozone offers the potential for use as a
+low-thermal budget processing tool.",0710.0803v1
+2007-12-05,"The epitaxial-graphene/graphene-oxide junction, an essential step towards epitaxial graphene electronics","Graphene oxide (GO) flakes have been deposited to bridge the gap between two
+epitaxial graphene electrodes to produce all-graphene devices. Electrical
+measurements indicate the presence of Schottky barriers (SB) at the
+graphene/graphene oxide junctions, as a consequence of the band-gap in GO. The
+barrier height is found to be about 0.7 eV, and is reduced after annealing at
+180 $^\circ$C, implying that the gap can be tuned by changing the degree of
+oxidation. A lower limit of the GO mobility was found to be 850 cm$^2$/Vs,
+rivaling silicon. {\it In situ} local oxidation of patterned epitaxial graphene
+has been achieved.",0712.0820v2
+2008-11-12,Synthesis of infinite-layer LaNiO2 films by metal-organic deposition,"We report the synthesis of infinite-layer LaNiO2 thin films by metal organic
+decomposition. Our work is aimed to synthesize perovskite-like oxides with 3d9
+electronic configuration, which is common to high-Tc copper oxides. The 3d9
+configuration is very rare in oxides other than cuprates. Ni1+ oxides, even
+though Ni1+ is an unusual oxidation state, may be one of very few candidates.
+One example of the Ni1+ phases is infinite-layer LaNiO2. The bulk synthesis of
+LaNiO2 is difficult, but we demonstrate in this article that the thin-film
+synthesis of LaNiO2 by metal organic decomposition is rather easy. This is due
+to the advantage of thin films with a large-surface-to-volume ratio, which
+makes oxygen diffusion prompt. Resistivity measurements indicate that LaNiO2 is
+essentially a metal but unfortunately with no trace of superconductivity yet.",0811.1858v1
+2009-03-06,Ab initio structure modeling of complex thin-film oxides: thermodynamical stability of TiC/thin-film alumina,"We present an efficient and general method to identify promising candidate
+configurations for thin-film oxides and to determine structural characteristics
+of (metastable) thin-film structures using ab initio calculations. At the heart
+of this method is the complexity of the oxide bulk structure, from which a
+large number of thin films with structural building blocks, that is motifs,
+from metastable bulk oxide systems can be extracted. These span a coarse but
+well-defined network of initial configurations for which density functional
+theory (DFT) calculations predict and implement dramatic atomic relaxations in
+the corresponding, resulting thin-film candidates. The network of thin-film
+candidates (for various film thicknesses and stoichiometries) can be ordered
+according to their variation in ab initio total energy or in ab initio
+equilibrium Gibbs free energy. Analysis of the relaxed atomic structures for
+the most favored structures gives insight into the nature of stable and
+metastable thin-film oxides. We investigate ultrathin alumina nucleated on TiC
+as a model system to illustrate this method.",0903.1252v1
+2009-03-25,"Adsorption of benzene, phenol, propane and carbonic acid molecules on oxidized Al(111) and alpha-Al2O3(0001) surfaces: A first-principles study","We present the results of ab initio calculations describing the adsorption of
+certain small organic molecules on clean and oxidized Al(111) surfaces as well
+as on the alpha-Al2O3(0001) surface. Our results show that adsorption of
+benzene on the clean and oxidized Al(111) surfaces is generally weak, the
+adsorption energy being at most around -0.5 eV per benzene molecule, and the
+molecule adsorbed at a considerable distance from the surfaces. The adsorption
+energy varies weakly at the different adsorption sites and as a function of the
+oxygen coverage. For the alumina surface, we find no benzene adsorption at all.
+We have also calculated a phenol molecule on the aluminium and alumina
+surfaces, since it is similar to the benzene molecule. The results show a weak
+adsorption for phenol on the alumina surface and no adsorption on the aluminium
+or oxidized aluminium surfaces at all. For the propane molecule there is no
+adsorption on either the oxidized aluminium or the alumina surface, whereas the
+carbonic acid molecule binds strongly to the alumina but not to the aluminium
+surface.",0903.4306v1
+2009-04-14,Density functional theory study of Fe(II) adsorption and oxidation on goethite surfaces,"We study the interactions between Fe(II) aqua complexes and surfaces of
+goethite (alpha-FeOOH) by means of density functional theory calculations
+including the so-called Hubbard U correction to the exchange-correlation
+functional. Using a thermodynamic approach, we find that (110) and (021)
+surfaces in contact with aqueous solutions are almost equally stable, despite
+the evident needlelike shape of goethite crystals indicating substantially
+different reactivity of the two faces. We thus suggest that crystal anisotropy
+may result from different growth rates due to virtually barrierless adsorption
+of hydrated ions on the (021) but not on the (110) surface. No clear evidence
+is found for spontaneous electron transfer from an adsorbed Fe(II) hex-aqua
+complex to a defect-free goethite substrate. Crystal defects are thus inferred
+to play an important role in assisting such electron transfer processes
+observed in a recent experimental study. Finally, goethite surfaces are
+observed to enhance the partial oxidation of adsorbed aqueous Fe(II) upon
+reaction with molecular oxygen. We propose that this catalytic oxidation effect
+arises from donation of electronic charge from the bulk oxide to the oxidizing
+agent through shared hydroxyl ligands anchoring the Fe(II) complexes on the
+surface.",0904.2111v1
+2009-04-23,Microscopic origin of bipolar resistive switching of nanoscale titanium oxide thin films,"We report a direct observation of the microscopic origin of the bipolar
+resistive switching behavior in nanoscale titanium oxide films. Through a
+high-resolution transmission electron microscopy, an analytical TEM technique
+using energy-filtering transmission electron microscopy and an in situ x-ray
+photoelectron spectroscopy, we demonstrated that the oxygen ions piled up at
+top interface by an oxidation-reduction reaction between the titanium oxide
+layer and the top Al metal electrode. We also found that the drift of oxygen
+ions during the on/off switching induced the bipolar resistive switching in the
+titanium oxide thin films.",0904.3628v2
+2011-01-29,Multi-component Transparent Conducting Oxides: Progress in Materials Modelling,"Transparent conducting oxides (TCOs) play an essential role in modern
+optoelectronic devices through their combination of electrical conductivity and
+optical transparency. We review recent progress in our understanding of
+multi-component TCOs formed from solid-solutions of ZnO, In2O3, Ga2O3 and
+Al2O3, with a particular emphasis on the contributions of materials modelling,
+primarily based on Density Functional Theory. In particular, we highlight three
+major results from our work: (i) the fundamental principles governing the
+crystal structures of multi-component oxide structures including (In2O3)(ZnO)n,
+named IZO, and (In2O3)m(Ga2O3)l(ZnO)n, named IGZO; (ii) the relationship
+between elemental composition and optical and electrical behaviour, including
+valence band alignments; (iii) the high-performance of amorphous oxide
+semiconductors. From these advances, the challenge of the rational design of
+novel electroceramic materials is discussed.",1101.5720v1
+2012-03-12,Graphene coatings: An efficient protection from oxidation,"We demonstrate that graphene coating can provide an efficient protection from
+oxidation by posing a high energy barrier to the path of oxygen atom, which
+could have penetrated from the top of graphene to the reactive surface
+underneath. Graphene bilayer, which blocks the diffusion of oxygen with a
+relatively higher energy barrier provides even better protection from
+oxidation. While an oxygen molecule is weakly bound to bare graphene surface
+and hence becomes rather inactive, it can easily dissociates into two oxygen
+atoms adsorbed to low coordinated carbon atoms at the edges of a vacancy. For
+these oxygen atoms the oxidation barrier is reduced and hence the protection
+from oxidation provided by graphene coatings is weakened. Our predictions
+obtained from the state of the art first-principles calculations of electronic
+structure, phonon density of states and reaction path will unravel how a
+graphene can be used as a corrosion resistant coating and guide further studies
+aiming at developing more efficient nanocoatings.",1203.2580v1
+2012-06-25,Local Conduction at the BiFeO3-CoFe2O4 Tubular Oxide Interface,"In strongly correlated oxides, heterointerfaces, manipulating the
+interaction, frustration, and discontinuity of lattice, charge, orbital, and
+spin degrees of freedom, generate new possibilities for next generation
+devices. In this study, we went back to examine the existing oxide
+heterostructures and found the local conduction at the BiFeO3-CoFe2O4 vertical
+interface. In such hetero-nanostructure, the tubular interface, surrounding
+BiFeO3-CoFe2O4 vertical interface, can not only be the medium to the coupling
+between phases, but also be a new state of the matter. Our study demonstrates a
+novel concept on oxide interface design and opens a pathway alternative for the
+explorations of diverse functionalities in complex oxide interfaces.",1206.5599v2
+2012-09-28,Oxidation effects on graded porous silicon anti-reflection coatings,"Efficient anti-reflection coatings (ARC) improve the light collection and
+thereby increase the current output of solar cells. By simple electrochemical
+etching of the Si wafer, porous silicon (PS) layers with excellent broadband
+anti-reflection properties can be fabricated. In this work, ageing of graded PS
+has been studied using Spectroscopic Ellipsometry, Transmission Electron
+Microscopy and X-ray Photoelectron Spectroscopy. During oxidation of PS
+elements such as pure Si (Si$^0$), Si$_2$O (Si$^+$), SiO (Si$^{2+}$),
+Si$_2$O$_3$ (Si$^{3+}$), and SiO$_2$ (Si$^{4+}$) are present. In addition both
+hydrogen and carbon is introduced to the PS in the form of Si$_3$SiH and CO.
+The oxide grows almost linearly with time when exposed to oxygen, from an
+average thickness of 0 - 3.8 nm for the surface PS. The oxidation is then
+correlated to the optical stability of multi-layered PS ARCs. It is found that
+even after extensive oxidation, the changes in the optical properties of the PS
+structures are small.",1210.0038v1
+2012-11-28,Stability of xenon oxides at high pressures,"Xenon, which is quite inert under ambient conditions, may become reactive
+under pressure. The possibility of formation of stable xenon oxides and
+silicates in the interior of the Earth could explain the atmospheric missing
+xenon paradox. Using the ab initio evolutionary algorithm, we predict the
+thermodynamical stabilization of Xe-O compounds at high pressures (XeO, XeO2
+and XeO3 at pressures above 83, 102 and 114 GPa, respectively). Our
+calculations indicate large charge transfer in these oxides, suggesting that
+large electronegativity difference and pressure are the key factors favoring
+the formation of xenon compounds. Xenon compounds in the Earth's mantle,
+however, cannot directly explain the missing xenon paradox: xenon oxides are
+unstable in equilibrium with metallic iron in the Earth's lower mantle, while
+xenon silicates are predicted to spontaneously decompose at all mantle
+pressures (<136 GPa). This does not preclude Xe atoms from being retained in
+defects of mantle silicates and oxides.",1211.6520v2
+2013-01-15,CO oxidation on Pd(100) vs. PdO(sqrt5xsqrt5)R27^o: First-Principles Kinetic Phase Diagrams and Bistability Conditions,"We present first-principles kinetic Monte Carlo (1p-kMC) simulations
+addressing the CO oxidation reaction at Pd(100) for gas-phase conditions
+ranging from ultra-high vacuum (UHV) to ambient pressures and elevated
+temperatures. For the latter technologically relevant regime there is a
+long-standing debate regarding the nature of the active surface. The pristine
+metallic surface, an ultra-thin (sqrt5xsqrt5)R27^o PdO(101) surface oxide, and
+thicker oxide layers have each been suggested as the active state. We
+investigate these hypotheses with 1p-kMC simulations focusing on either the
+Pd(100) surface or the PdO(101) surface oxide and intriguingly obtain a range
+of (T, p)-conditions where both terminations appear metastable. The predicted
+bistability regime nicely ties in with oscillatory behavior reported
+experimentally by Hendriksen and coworkers [Catal. Today 105, 234 (2005)].
+Within this regime we find that both surface terminations exhibit very similar
+intrinsic reactivity, which puts doubts on attempts to assign the catalytic
+function to just one active state.",1301.3285v1
+2013-01-26,Monitoring the formation of oxide apertures in micropillar cavities,"An imaging technique is presented that enables monitoring of the wet thermal
+oxidation of a thin AlAs layer embedded between two distributed Bragg reflector
+(DBR) mirrors in a micropillar. After oxidation we confirm by white light
+reflection spectroscopy that high quality optical modes confined to a small
+volume have been formed. The combination of these two optical techniques
+provides a reliable and efficient way of producing oxide apertured micropillar
+cavities for which the wet thermal oxidation is a critical fabrication step.",1301.6248v2
+2013-03-16,The influence of residual oxidizing impurities on the synthesis of graphene by atmospheric pressure chemical vapor deposition,"The growth of graphene on copper by atmospheric pressure chemical vapor
+deposition in a system free of pumping equipment is investigated. The emphasis
+is put on the necessity of hydrogen presence during graphene synthesis and
+cooling. In the absence of hydrogen during the growth step or cooling at slow
+rate, weak carbon coverage, consisting mostly of oxidized and amorphous carbon,
+is obtained on the copper catalyst. The oxidation originates from the
+inevitable occurrence of residual oxidizing impurities in the reactor's
+atmosphere. Graphene with appreciable coverage can be grown within the
+vacuum-free furnace only upon admitting hydrogen during the growth step. After
+formation, it is preserved from the destructive effect of residual oxidizing
+contaminants once exposure at high temperature is minimized by fast cooling or
+hydrogen flow. Under these conditions, micrometer-sized hexagon-shaped graphene
+domains of high structural quality are achieved.",1303.3951v2
+2013-06-11,A Preliminary Study of Oxidation of Lignin from Rubber Wood to Vanillin in Ionic Liquid Medium,"In this study, lignin was oxidised to vanillin by means of oxygen in ionic
+liquid (1,3-dimethylimidazolium methylsulphate) medium. The parameters of the
+oxidation reaction that have been investigated were the following:
+concentration of oxygen (5, 10, 15 and 20 ft3 h-1), reaction time (2, 4, 6, 8
+and 10 h) and reaction temperature (25, 40, 60, 80 and 100{\deg}C). The Fourier
+transform infrared spectroscopy, high performance liquid chromatography and
+ultraviolet-visible analyses were used to characterise the product. The results
+revealed vanillin as the product obtained via the oxidation reaction. The
+optimum parameters of vanillin production were 20 ft3 h-1 of oxygen for 10 h at
+100{\deg}C. In conclusion, 1,3-dimethylimidazolium methylsulphate could be used
+as an oxidation reaction medium for the production of vanillin from rubber wood
+lignin.",1306.2442v1
+2013-07-24,Origin of Anomalous Water Permeation through Graphene Oxide Membrane,"Water inside the low dimensional carbon structures has been considered
+seriously owing to fundamental interest in its flow and structures as well as
+its practical impact. Recently, the anomalous perfect penetration of water
+through graphene oxide membrane was demonstrated although the membrane was
+impenetrable for other liquids and even gases. The unusual auxetic behavior of
+graphene oxide in the presence of water was also reported. Here, based on
+first-principles calculations, we establish atomistic models for hybrid systems
+composed of water and graphene oxides revealing the anomalous water behavior
+inside the stacked graphene oxides. We show that formation of hexagonal ice
+bilayer in between the flakes as well as melting transition of ice at the edges
+of flakes are crucial to realize the perfect water permeation across the whole
+stacked structures. The distance between adjacent layers that can be controlled
+either by oxygen reduction process or pressure is shown to determine the water
+flow thus highlighting a unique water dynamics in randomly connected
+two-dimensional spaces.",1307.6312v1
+2014-08-03,Thermopower enhancement by fractional layer control in 2D oxide superlattices,"We have investigated two-dimensional thermoelectric properties in transition
+metal oxide heterostructures. In particular, we adopted an unprecedented
+approach to direct tuning of the 2D carrier density using fractionally
+{\delta}-doped oxide superlattices. By artificially controlling the carrier
+density in the 2D electron gas that emerges at a LaxSr1-xTiO3 {\delta}-doped
+layer, we demonstrate that a thermopower as large as 408 {\mu}V K-1 can be
+reached. This approach also yielded a power factor of the 2D carriers 117
+{\mu}Wcm-1K-2, which is one of the largest reported values from transition
+metal oxide based materials. The promising result can be attributed to the
+anisotropic band structure in the 2D system, indicating that {\delta}-doped
+oxide superlattices can be a good candidate for advanced thermoelectrics.",1408.0449v1
+2014-10-27,Band-gap engineering at a semiconductor - crystalline oxide interface,"The epitaxial growth of crystalline oxides on semiconductors provides a
+pathway to introduce new functionalities to semiconductor devices. Key to
+electrically coupling crystalline oxides with semiconductors to realize
+functional behavior is controlling the manner in which their bands align at
+interfaces. Here we apply principles of band gap engineering traditionally used
+at heterojunctions between conventional semiconductors to control the band
+offset between a single crystalline oxide and a semiconductor. Reactive
+molecular beam epitaxy is used to realize atomically abrupt and structurally
+coherent interfaces between SrZr$_{x}$Ti$_{1-x}$O$_3$ and Ge, in which the
+band-gap of the former is enhanced with Zr content $x$. We present structural
+and electrical characterization of SrZr$_{x}$Ti$_{1-x}$O$_3$-Ge heterojunctions
+for $x$ = 0.2 to 0.75 and demonstrate the band offset can be tuned from type-II
+to type-I, with the latter being verified using photoemission measurements. The
+type-I band offset provides a platform to integrate the dielectric,
+ferroelectric and ferromagnetic functionalities of oxides with semiconducting
+devices.",1410.7327v1
+2015-06-19,Inverse spin Hall effect in a complex ferromagnetic oxide heterostructure,"Complex oxide heterostructures are hot candidates for post CMOS
+multi-functional devices. Especially in spintronics applications ferromagnetic
+oxides may play a key role because they can exhibit extraordinary high spin
+polarization. Indeed, there are already plenty of examples in spintronics,
+notably in the area of spin pumping and inverse spin Hall effect (ISHE)
+\cite{Azevedo2011, Czeschka2011, Hahn2013, Obstbaum2014}. Although complex
+oxides have been used in these experiments as a source of spin currents, they
+have never been demonstrated to act as a spin sink that exhibits ISHE. Here we
+show that in a heterostructure consisting of La$_{0.7}$Sr$_{0.3}$MnO$_{3}$
+(LSMO) and SrRuO$_{3}$ (SRO) the low temperature ferromagnet SRO can act as a
+spin sink and exhibit a sizeable ISHE which persists even below its Curie
+temperature. This result opens up new possibilities for application of all
+oxide heterostructures in spintronics and may significantly extend the research
+on spin Hall effect and related phenomena.",1506.05921v1
+2015-06-24,Resonant tunneling in a quantum oxide superlattice,"Resonant tunnelling is a quantum mechanical process that has long been
+attracting both scientific and technological attention owing to its intriguing
+underlying physics and unique applications for high-speed electronics. The
+materials system exhibiting resonant tunnelling, however, has been largely
+limited to the conventional semiconductors, partially due to their excellent
+crystalline quality. Here we show that a deliberately designed transition metal
+oxide superlattice exhibits a resonant tunnelling behaviour with a clear
+negative differential resistance. The tunnelling occurred through an atomically
+thin, lanthanum {\delta}-doped SrTiO3 layer, and the negative differential
+resistance was realized on top of the bipolar resistance switching typically
+observed for perovskite oxide junctions. This combined process resulted in an
+extremely large resistance ratio (~10^5) between the high and low-resistance
+states. The unprecedentedly large control found in atomically thin
+{\delta}-doped oxide superlattices can open a door to novel oxide-based
+high-frequency logic devices.",1506.07583v1
+2015-09-28,Solid-state chemistry of glassy antimony oxides,"The amorphous phases of antimony oxide at three different oxidation levels
+have been investigated by {\it ab initio} molecular-dynamics calculations using
+a simulated `melt-quench' approach. The atomic and electronic structure of the
+amorphous phases are analyzed and compared to their crystalline counterparts.
+The amorphous structure of the trioxide ({\it a\,}--Sb$_2$O$_3$) resembles the
+$\beta$-phase of the crystalline form (valentinite), in agreement with previous
+observations. In the relaxed athermal structure, however, more
+senarmontite-like structural features are apparent. The phase diagram of the
+amorphous phases with respect to oxygen chemical potential has been calculated
+within the framework of {\it ab initio} thermodynamics. At elevated oxidation
+levels, the resulting tetraoxide and pentoxide materials show distinct
+variation in electronic structure compared to the trioxide, with the electronic
+density of states indicating a narrowing of the electronic gap with increasing
+oxidation level.",1509.08192v1
+2015-10-29,Degenerate epitaxy-driven defects in monolayer silicon oxide onto ruthenium,"The structure of the ultimately-thin crystalline allotrope of silicon oxide,
+prepared onto a ruthenium surface, is unveiled down to atomic scale with
+chemical sensitivity, thanks to high resolution scanning tunneling microscopy
+and first principle calculations. An ordered oxygen lattice is imaged which
+coexists with the two-dimensional monolayer oxide. This coexistence signals a
+displacive transformation from an oxygen reconstructed-Ru(0001) to silicon
+oxide, along which latterally-shifted domains form, each with equivalent and
+degenerate epitaxial relationships with the substrate. The unavoidable
+character of defects at boundaries between these domains appeals for the
+development of alternative methods capable of producing single-crystalline
+two-dimensional oxides.",1510.08607v1
+2015-11-21,Single Crystal Functional Oxides on Silicon,"Single crystalline thin films of complex oxides show a rich variety of
+functional properties such as ferroelectricity, piezoelectricity, ferro and
+antiferromagnetism etc. that have the potential for completely new electronic
+applications (1-2). Direct synthesis of such oxides on Si remains challenging
+due to the fundamental crystal chemistry and mechanical incompatibility of
+dissimilar interfaces (3-16). Here we report integration of thin (down to 1
+unit cell) single crystalline, complex oxide films onto Si substrates, by
+epitaxial transfer at room temperature. In a field effect transistor using a
+transferred Pb0.2Zr0.8TiO3 (PZT) layer as the gate insulator, we demonstrate
+direct reversible control of the semiconductor channel charge with polarization
+state. These results represent the realization of long pursued but yet to be
+demonstrated single crystal functional oxides on-demand on silicon.",1511.06832v1
+2016-01-27,Graphene oxide and adsorption of chloroform: a density functional study,"Chlorinated hydrocarbon compounds are of environmental concerns, since they
+are toxic to humans and other mammals, are widespread, and exposure is hard to
+avoid. Understanding and improving methods to reduce the amount of the
+substances is important. We present an atomic-scale calculational study of the
+adsorption of chlorine-based substance chloroform (CHCl3) on graphene oxide, as
+a step in estimating the capacity of graphene oxide for filtering out such
+substances, e.g., from drinking water. The calculations are based on density
+functional theory (DFT), and the recently developed consistent-exchange
+functional for the van der Waals density-functional method (vdW-DF-cx) is
+employed. We obtain values of the chloroform adsorption energy varying from
+roughly 0.2 to 0.4 eV per molecule. This is comparable to previously found
+results for chloroform adsorbed directly on clean graphene, using similar
+calculations. In a wet environment, like filters for drinking water, the
+graphene will not stay clean and will likely oxidize, and thus adsorption onto
+graphene oxide, rather than clean graphene, is a more relevant process to
+study.",1601.07329v1
+2016-02-22,Laser-assisted Oxidation of Multi-layer Tungsten Diselenide Nanosheets,"We report the structural and electrical characterization of tungsten oxides
+formed by illuminating multi-layer tungsten diselenide (WSe2) nanosheets with
+an intense laser beam in the ambient environment. A noninvasive microwave
+impedance microscope (MIM) was used to perform electrical imaging of the
+samples. The local conductivity ~100 S/m of the oxidized product, measured by
+the MIM and conventional transport experiments, is much higher than that of the
+pristine WSe2, suggesting the formation of sub-stoichiometric WO3-x
+polycrystals with n-type carriers. With further efforts to improve the
+conductivity of the oxides, the laser-assisted oxidation process may be useful
+for patterning conductive features on WSe2 or forming electrical contacts to
+various transition metal dichalcogenides.",1602.06639v1
+2016-07-08,High Tc superconductivity at the interface between the CaCuO2 and SrTiO3 insulating oxides,"At interfaces between complex oxides it is possible to generate electronic
+systems with unusual electronic properties, which are not present in the
+isolated oxides. One important example is the appearance of superconductivity
+at the interface between insulating oxides, although, until now, with very low
+Tc. We report the occurrence of high Tc superconductivity in the bilayer
+CaCuO2/SrTiO3, where both the constituent oxides are insulating. In order to
+obtain a superconducting state, the CaCuO2/SrTiO3 interface must be realized
+between the Ca plane of CaCuO2 and the TiO2 plane of SrTiO3. Only in this case
+extra oxygen ions can be incorporated in the interface Ca plane, acting as
+apical oxygen for Cu and providing holes to the CuO2 planes. A detailed hole
+doping spatial profile has been obtained by STEM/EELS at the O K-edge, clearly
+showing that the (super)conductivity is confined to about 1-2 CaCuO2 unit cells
+close to the interface with SrTiO3. The results obtained for the CaCuO2/SrTiO3
+interface can be extended to multilayered high Tc cuprates, contributing to
+explain the dependence of Tc on the number of CuO2 planes in these systems.",1607.02449v1
+2016-10-27,Hybrid electrochromic device with Tungsten oxide (WO3-x) and nafion membrane: performance with varying tungsten oxide thickness,"Electrochromic devices, which dynamically change color under the applied
+potential, are widely studied because of its wide range of applications such as
+energy-efficient smart windows, rear view mirrors and display devices etc. In
+this study we are reporting four layer electrochromic device based on tungsten
+oxide as a electrochromic layer and nafion membrane as a ionic conducting
+layer. Nafion membranes are generally used in fuel cell applications because of
+its high ionic conductivity and high optical transparency which is suitable for
+electrochromic device to attain higher efficiencies. We have prepared an
+electrochromic device by sandwiching ITO coated glass and WO3 coated ITO thin
+film between nafion membrane. The overall structure of the device is
+Glass/ITO/WO3/Nafion/ITO/Glass. We deposited tungsten oxide thin films with
+different thickness on ITO coated glass substrate at room temperature by using
+reactive DC Magnetron sputtering and we studied the performance of the
+electrochromic device with the function of thickness. We have observed that
+electrochromic efficiency is increasing with increase in the tungsten oxide
+layer thickness. The efficiency of the device increased from 24.8 cm2/C to
+184.3 cm2/C.",1610.08807v1
+2017-08-05,Copper-oxide Nanowires based Humidity Sensor,"This paper presents investigated results of copper-oxide nanowires used as a
+humidity sensor. Copper-oxide nanowires films were grown over cross-comb type
+gold electrodes on a SiO2 substrate using thermal annealing technique, and its
+humidity sensitive characteristics were investigated through resistance across
+the gold electrodes. These copper-oxide nanowires films revealed high
+sensitivity and long-term stability with fast response time. It was found that
+resistance across gold electrodes of the fabricated sensor decreases with
+increase in humidity almost linearly on a logarithmic scale. It appears that
+copper-oxide nanowires can be used as low-cost humidity sensor with high output
+reliability and reproduction rate. The observations were carried out at room
+temperature (RT) and relative humidity (RH) in the range of 6% to 97%.",1708.01720v1
+2018-02-07,"Stability of boron-doped graphene/copper interface: DFT, XPS and OSEE studies","Two different types of boron-doped graphene/copper interfaces synthesized
+using two different flow rates of Ar through the bubbler containing the boron
+source were studied. X-ray photoelectron spectra (XPS) and optically stimulated
+electron emission (OSEE) measurements have demonstrated that boron-doped
+graphene coating provides a high corrosion resistivity of Cu-substrate with the
+light traces of the oxidation of carbon cover. The density functional theory
+calculations suggest that for the case of substitutional (graphitic)
+boron-defect only the oxidation near boron impurity is energetically favorable
+and creation of the vacancies that can induce the oxidation of copper substrate
+is energetically unfavorable. In the case of non-graphitic boron defects
+oxidation of the area, a nearby impurity is metastable that not only prevent
+oxidation but makes boron-doped graphene. Modeling of oxygen reduction reaction
+demonstrates high catalytic performance of these materials.",1802.02345v1
+2018-04-13,Subsurface Cation Vacancy Stabilization of the Magnetite (001) Surface,"Iron oxides play an increasingly prominent role in heterogeneous catalysis,
+hydrogen production, spintronics and drug delivery. The surface or material
+interface can be performance limiting in these applications, so it is vital to
+determine accurate atomic-scale structures for iron oxides and understand why
+they form. Using a combination of quantitative low-energy electron diffraction,
+scanning tunneling microscopy, and density functional theory calculations, we
+show that an ordered array of subsurface iron vacancies and interstitials
+underlies the well-known (rt2xrt2)R45{\deg} reconstruction of Fe3O4(001). This
+hitherto unobserved stabilization mechanism occurs because the iron oxides
+prefer to redistribute cations in the lattice in response to oxidizing or
+reducing environments. Many other metal oxides also achieve stoichiometric
+variation in this way, so such surface structures are likely commonplace.",1804.04836v1
+2018-11-06,"Effect of pre-oxidation treatments on the structural, microstructural, and chemical properties of (Ni,Pt)Al systems","The effect of isothermal pre-oxidation treatments on the \b{eta}-(Ni,Pt)Al +
+Ren\'e N5 system degradation is here reported. The oxidation treatments were
+carried out from 900 (mostly {\theta}-Al2O3 growing conditions) to 1200{\deg}C
+(mainly {\alpha}-Al2O3 growing conditions) for 5 h, under a purified Ar-stream
+with a fixed pO2= 1 x 10-5 atm. Results are discussed based on the correlation
+between the structural, microstructural and chemical properties of the
+\b{eta}-(Ni,Pt)Al BC showing that pre-oxidation parameters have an important
+effect on the multi-elemental counter diffusion phenomena along BC. For
+instance, a significant BC+IDZ thickness increase of 55% at 1200 {\deg}C was
+observed with respect to as-received sample just after 5 h of oxidation
+resulting in a severe BC degradation.",1811.02176v1
+2019-05-07,Mechanism of CO-oxidation on Pd/CeO2(100): The unique surface-structure of CeO2(100) and the role of peroxide,"Understanding the atomic mechanism of low-temperature CO oxidation on a
+heterogeneous catalyst is challenging. We performed density functional theory
+(DFT) calculations to identify the surface structure and reaction mechanism
+responsible for low-temperature CO oxidation on Pd/CeO2 (100) surfaces. DFT
+calculations reveal the formation of a unique zigzag chain structure by the
+oxygen and Ce atoms of the topmost surface of CeO2(100) with Pd atoms located
+between the zigzag chains. O2 adsorbed on such Pd atoms is stable in the
+presence of CO but plays a very important role in lowering the activation
+barrier for low-temperature CO oxidation by forming a square-planar PdO4
+structure and facilitating further O2 adsorption. In-situ Raman spectroscopy
+studies confirm the adsorbed oxygen species to be peroxides. The calculated
+activation barrier for CO oxidation, based on the mechanism suggested by these
+unique structures and peroxides, is 31.2 kJ/mol, in excellent agreement with
+our experimental results.",1905.02398v1
+2013-08-20,Quantifying Oxidation Rates of Carbon Monoxide on a Pt/C Electrode,"The electrochemical oxidation of carbon monoxide adsorbed (COad) on
+platinum-on-carbon electrodes was studied via a methodology in which
+pre-adsorbed CO was partially oxidized by applying potentiostatic pulses for
+certain durations. The residual COad was analyzed using stripping voltammetry
+that involved the deconvolution of COad oxidation peaks of voltammograms to
+quantify the weakly and strongly bound species of COad. The data obtained for
+various potentials and temperatures were fit to a model based on a nucleation
+and growth mechanism. The resulting fit produced potential- and
+temperature-dependent rate parameters that provided insight into the oxidation
+mechanism of the two COad species. Irrespective of the applied potential or
+temperature, the concentration of weakly bound COad species decreased
+exponentially with time. In contrast, the strongly bound COad species showed a
+gradual transition of mechanisms, from progressive nucleation at relatively low
+potentials to exponential decay at high potentials.",1308.4317v1
+2018-05-02,Local anodic oxidation on hydrogen-intercalated graphene layers: oxide composition analysis and role of the silicon carbide substrate,"We investigate nanoscale local anodic oxidation (LAO) on
+hydrogen-intercalated graphene grown by controlled sublimation of silicon
+carbide (SiC). Scanning probe microscopy (SPM) was used as a lithographic and
+characterization tool in order to investigate the local properties of the
+nanofabricated structures. The anomalous thickness observed after the graphene
+oxidation process is linked to the impact of LAO on the substrate. Micro-Raman
+spectroscopy was employed to demonstrate the presence of two oxidation regimes
+depending on the applied bias. We show that partial and total etching of
+monolayer graphene can be achieved by tuning the bias voltage during LAO.
+Finally, a complete compositional characterization was achieved by scanning
+electron microscopy and energy dispersive spectroscopy (EDS).",1805.00673v1
+2018-05-07,Chemistry with Graphene and Graphene Oxide - Challenges for Synthetic Chemists,"The chemical production of graphene as well as its controlled wet- chemical
+modification is a challenge for synthetic chemists and the characterization of
+reaction products requires sophisticated analytic methods. In this review we
+first describe the structure of graphene and graphene oxide. We then outline
+the most important synthetic methods which are used for the production of these
+carbon based nanomaterials. We summarize the state-of-the-art for their
+chemical functionalization by non-covalent and covalent approaches. We put
+special emphasis on the differentiation of the terms graphite, graphene,
+graphite oxide and graphene oxide. An improved fundamental knowledge about the
+structure and the chemical properties of graphene and graphene oxide is an
+important prerequisite for the development of practical applications.",1805.03088v1
+2018-05-08,Reduced-Graphene-Oxide with Traces of Iridium or Gold as Active Support for Pt Catalyst at Low Loading during Oxygen Electroreduction,"Chemically-reduced graphene-oxide-supported gold or iridium nanoparticles are
+considered here as active carriers for dispersed platinum with an ultimate goal
+of producing improved catalysts for electroreduction of oxygen in acid medium.
+Comparison is made to the analogous systems not utilizing reduced graphene
+oxide. High electrocatalytic activity of platinum (loading up to 30 {\mu}g
+cm-2) dispersed over the reduced-graphene oxide-supported Au (up to 30 {\mu}g
+cm-2) or Ir (up to 1.5 {\mu}g cm-2) nanoparticles toward reduction of oxygen
+has been demonstrated using cyclic and rotating ring-disk electrode (RRDE)
+voltammetric experiments. Among important issues are possible activating
+interactions between gold and the support, as well as presence of structural
+defects existing on poorly organized graphitic structure of reduced graphene
+oxide. The RRDE data are consistent with decreased formation of hydrogen
+peroxide.",1805.03147v1
+2009-12-01,Oxidation States of Graphene: Insights from Computational Spectroscopy,"When it is oxidized, graphite can be easily exfoliated forming graphene oxide
+(GO). GO is a critical intermediate for massive production of graphene, and it
+is also an important material with various application potentials. With many
+different oxidation species randomly distributed on the basal plane, GO has a
+complicated nonstoichiometric atomic structure that is still not well
+understood in spite of of intensive studies involving many experimental
+techniques. Controversies often exist in experimental data interpretation. We
+report here a first principles study on binding energy of carbon 1s orbital in
+GO. The calculated results can be well used to interpret experimental X-ray
+photoelectron spectroscopy (XPS) data and provide a unified spectral
+assignment. Based on the first principles understanding of XPS, a GO structure
+model containing new oxidation species epoxy pair and epoxy-hydroxy pair is
+proposed. Our results demonstrate that first principles computational
+spectroscopy provides a powerful means to investigate GO structure.",0912.0085v1
+2012-04-25,A Computational Investigation of the Catalytic Properties of Graphene Oxide: Exploring Mechanisms Using DFT Methods,"Here we describe a computational study undertaken in an effort to elucidate
+the reaction mechanisms behind the experimentally observed oxidations and
+hydrations catalyzed by graphene oxide (GO). Using the oxidation of benzyl
+alcohol to benzaldehyde as a model reaction, density functional theory (DFT)
+calculations revealed that this reactivity stemmed from the transfer of
+hydrogen atoms from the organic molecule to the GO surface. In particular,
+neighbouring epoxide groups decorating GO's basal plane were ring-opened,
+resulting in the formation of diols, followed by dehydration. Consistent with
+the experimentally-observed dependence of this chemistry on molecular oxygen,
+our calculations revealed that the partially reduced catalyst was able to be
+recharged by molecular oxygen, allowing for catalyst turnover. Functional
+group-free carbon materials, such as graphite, were calculated to have
+substantially higher reaction barriers, indicating that the high chemical
+potential and rich functionality of GO are necessary for the observed
+reactivity.",1204.5557v1
+2012-04-28,Low Frequency Dielectric Loss of Metal/Insulator/Organic Semiconductor Junctions in Ambient Conditions,"The complex admittance of metal/oxide/pentacene thin film junctions is
+investigated under ambient conditions. At low frequencies, a contribution
+attributed to proton diffusion through the oxide is seen. This diffusion is
+shown to be anomalous and is believed to be also at the origin of the bias
+stress effect observed in organic field effect transistors. At higher
+frequencies, two dipolar contributions are evidenced, attributed to defects
+located one at the organic/oxide interface or within the organic, and the other
+in the bulk of the oxide. These two dipolar responses show different dynamic
+properties that manifest themselves in the admittance in the form of a Debye
+contribution for the defects located in the oxide, and of a Cole-Cole
+contribution for the defects related to the organic.",1204.6406v1
+2016-08-22,Cohesive energy and structural parameters of binary oxides of groups IIA and IIIB from diffusion quantum Monte Carlo,"We have applied the diffusion quantum Monte Carlo (DMC) method to calculate
+the cohesive energy and the structural parameters of the binary oxides CaO,
+SrO, BaO, Sc2O3, Y2O3 and La2O3. The aim of our calculations is to
+systematically quantify the accuracy of the DMC method to study this type of
+metal oxides. The DMC results were compared with local, semi-local and hybrid
+Density Functional Theory (DFT) approximations as well as with experimental
+measurements. The DMC method yields cohesive energies for these oxides with a
+mean absolute deviation from experimental measurements of 0.18(2) eV, while
+with local, semi-local and hybrid DFT approximations the deviation is 3.06,
+0.94 and 1.23 eV, respectively. For lattice constants, the mean absolute
+deviation in DMC, local, semi-local and hybrid DFT approximations, are
+0.017(1), 0.07, 0.05 and 0.04 {\AA}, respectively. DMC is highly accurate
+method, outperforming the DFT approximations in describing the cohesive
+energies and structural parameters of these binary oxides.",1608.06321v1
+2018-01-22,Transfer of Graphene with Protective Oxide Layers,"Transfer of graphene, grown by Chemical Vapor Deposition (CVD), to a
+substrate of choice, typically involves deposition of a polymeric layer
+(typically, poly(methyl methacrylate, PMMA or polydimethylsiloxane, PDMS).
+These polymers are quite hard to remove without leaving some residues behind.
+Here we study a transfer of graphene with a protective thin oxide layer. The
+thin oxide layer is grown by Atomic Deposition Layer (ALD) on the graphene
+right after the growth stage on Cu foils. One can further aid the
+oxide-graphene transfer by depositing a very thin polymer layer on top of the
+composite (much thinner than the usual thickness) following by a more
+aggressive polymeric removal methods, thus leaving the graphene intact. We
+report on the nucleation growth process of alumina and hafnia films on the
+graphene, their resulting strain and on their optical transmission. We suggest
+that hafnia is a better oxide to coat the graphene than alumina in terms of
+uniformity and defects.",1801.07338v2
+2018-09-13,Dendritic Oxide Growth in Zero-Valent Iron Nanofilms Revealed by Atom Probe Tomography,"Atom probe tomography (APT) analysis of chemically pure nanofilms of
+zero-valent iron (Fe(0), or ZVI) and their thermal oxide nano-overlayers
+reveals the presence of dendritic iron oxide features that extend from the
+oxide nano-overlayer surface into the ZVI bulk. The dendrites are observed by
+APT to be in the 5 nm x 10 nm size range and form quickly under natural
+atmospheric conditions. Their growth into the ZVI lalyer is, within the limit
+of our three-month long study, self-limiting (i.e. their initial growth appears
+to quickly discontinue). The atomistic views presented here shed first light on
+the atmospheric corrosion process of Fe(0)-bearing engineered nanostructures
+and their surfaces in the limit of low bulk impurities. Possible roles of the
+newly identified oxidized iron dendrites are also discussed in the context of
+passivation processes limiting technological applications of Fe(0).",1809.04909v2
+2018-10-24,Calculation of the equilibrium composition of metallic and oxide melts during their interaction,"Thermodynamic equilibrium can be sometimes reached at the interaction between
+metal and oxide melts in high temperature welding and metallurgical processes.
+Calculation of equilibrium phase composition is also one of the stages (along
+with kinetics analysis) of building an end-to-end physical and chemical model
+of real processes. Developing a thermodynamic model of high temperature
+processes is described in many scientific sources (1-18). Thermodynamic
+patterns of oxidation-reduction reactions on the metal-slag melt interface are
+also taken into account when building phenomenological models of real welding,
+facing, and metallurgical processes (19-30). This paper deals with calculating
+an equilibrium phase composition for a specific reaction. A method proposed
+herein also takes into account an interaction among any number of chemical
+reactions in the metal-oxide melt interface that form an equilibrium phase
+composition",1810.10163v1
+2018-10-24,Simulation of metal-oxide melt interaction in view of kinetics of chemical reactions in the interphase boundary,"Thermodynamics analysis of oxidation-reduction reactions between metal melt
+and slag (1) provides answers to certain practical issues such as the path of
+specific chemical reactions, final (equilibrium) phase composition, and the
+elements that are reduced and oxidized at given physical parameters. Although
+considerable, this is obviously not enough to analyze real technological
+systems, because the required equilibrium cannot be normally achieved despite
+high temperatures of welding and metallurgical processes. Hence, a dynamic
+problem has to be resolved here, which is calculating phase composition as a
+function of time. This cannot be achieved without knowing the rates of element
+concentration changes in each and every phase, and also technological
+parameters of the process. Relevant studies are detailed in(2-19). This paper
+analyzes special kinetic features of physical and chemical processes in the
+metal and oxide melt interface.",1810.10166v1
+2019-06-19,Correlation between the Dzyaloshinskii-Moriya interaction and the orbital angular momentum at an oxide / ferromagnet interface,"We report on the Dzyaloshinskii-Moriya (DMI) interaction at the interface
+between a ferromagnet and an oxide. We demonstrate experimentally that oxides
+can give rise to DMI. By comparison of systems comprised of Pt/Co90Fe10/Oxide
+and Cu/Co90Fe10/Oxide, we also show how oxidation of one interface can enhance
+and add to the total DMI of that generated by the Pt interface. This is due to
+the fact that the DMI on both interfaces promotes left-handed chirality.
+Finally, by use of ferromagnetic resonance spectroscopy, we show that the DMI
+and the spectroscopic splitting factor, which is a measure of the orbital
+momentum, are correlated. This indicates the importance of hybridization and
+charge transfer at the oxide interface for the DMI.",1906.08395v1
+2019-10-27,Mechanoradicals in tensed tendon collagen as a new source of oxidative stress,"As established nearly a century ago, mechanoradicals originate from homolytic
+bond scission in polymers. The existence, nature and biological relevance of
+mechanoradicals in proteins, instead, are unknown. We here show that mechanical
+stress on collagen produces radicals and subsequently reactive oxygen species,
+essential biological signaling molecules. Electron-paramagnetic resonance (EPR)
+spectroscopy of stretched rat tail tendon, atomistic Molecular Dynamics
+simulations and quantum calculations show that the radicals form by bond
+scission in the direct vicinity of crosslinks in collagen. Radicals migrate to
+adjacent clusters of aromatic residues and stabilize on oxidized tyrosyl
+radicals, giving rise to a distinct EPR spectrum consistent with a stable
+dihydroxyphenylalanine (DOPA) radical. The protein mechanoradicals, as a yet
+undiscovered source of oxidative stress, finally convert into hydrogen
+peroxide. Our study suggests collagen I to have evolved as a radical sponge
+against mechano-oxidative damage and proposes a new mechanism for
+exercise-induced oxidative stress and redox-mediated pathophysiological
+processes.",1910.12190v1
+2012-02-13,Effect of nanostructured zinc oxide additives on the humidity and temperature sensing properties of cuprous oxide,"Present paper reports the effect of ZnO additives on humidity and temperature
+sensing properties of cuprous oxide. The cuprous oxide powder was mixed with
+10% and 25% ZnO by weight and these samples were pelletized by using hydraulic
+pressing machine. The sensing materials were also investigated by Scanning
+Electron Microscope (SEM) and X-ray Diffraction (XRD). SEM images show
+morphology and porosity of material. The average particles size of cuprous
+oxide was found to be 1.2 micron. The sheet like structures of ZnO is evident
+in micrographs. From XRD all peaks are well identified and crystallite size for
+defferent peaks has also been calculated. The pellets of sensing materials were
+subjected to annealing at temperatures 200, 400 and 600 degrees C respectively
+and were exposed to humidity and temperature variations. Electrical resistances
+of pellets were found to vary with humidity and temperature and were recorded.
+The sensitivity of sensors at various temperature and humidity levels was
+calculated.",1205.2707v1
+2012-05-29,Influence of polarizability on metal oxide properties studied by molecular dynamics simulations,"We have studied the dependence of metal oxide properties in molecular
+dynamics (MD) simulations on the polarizability of oxygen ions. We present
+studies of both liquid and crystalline structures of silica (SiO2), magnesia
+(MgO) and alumina (Al2O3). For each of the three oxides, two separately
+optimized sets of force fields were used: (i) Long-range Coulomb interactions
+between oxide and metal ions combined with a short-range pair potential. (ii)
+Extension of force field (i) by adding polarizability to the oxygen ions. We
+show that while an effective potential of type (i) without polarizable oxygen
+ions can describe radial distributions and lattice constants reasonably well,
+potentials of type (ii) are required to obtain correct values for bond angles
+and the equation of state. The importance of polarizability for metal oxide
+properties decreases with increasing temperature.",1205.6296v4
+2017-05-09,Native surface oxide turns alloyed silicon membranes into nanophononic metamaterials with ultra-low thermal conductivity,"A detailed understanding of the relation between microscopic structure and
+phonon propagation at the nan oscale is essential to design materials with
+desired phononic and thermal properties.Here we uncover a new mechanism of
+phonon interaction in surface oxidized membranes, i.e., native oxide layers
+interact with phonons in ultra-thin silicon membranes through local resonances.
+The local resonances reduce the low frequency phonon group velocities and
+shorten their mean free path. This effect opens up a new strategy for ultralow
+thermal conductivity design as it complements the scattering mechanism which
+scatters higher frequency modes effectively. The combination of native oxide
+layer and alloying with germanium in concentration as small as 5% reduces the
+thermal conductivity of silicon membranes to 100 time lower than the bulk. In
+addition, the resonance mechanism produced by native oxide surface layers is
+particularly effective for thermal condutivity reduction even at very low
+temperatures, at which only low frequency modes are populated.",1705.03143v1
+2017-09-11,Signature of growth-deposition technique on the properties of PECVD and thermal SiO2,"In this article, we report the process induced variation in the
+characteristics of PECVD deposited and thermally grown silicon dioxide (SiO2)
+thin film. We find key differences in the porosity, arrangement of the
+nano-pores, surface roughness, refractive index and electrical resistivity of
+the SiO2 thin films obtained by the two methods. While the occurrence of the
+nanoporous structure is an inherent property of the material and independent of
+the process of film growth or deposition, the arrangements of these nano-pores
+in the oxide film is process dependent. The distinct arrangements of the
+nano-pores are signatures of the deposition/growth processes. Morphological
+analysis has been carried out to demonstrate the difference between oxides
+either grown by thermal oxidation or through PECVD deposition. The tunable
+conductive behavior of the metal filled nano-porous oxides is also
+demonstrated, which has potential to be used as conductive oxides in various
+applications.",1709.03257v1
+2017-09-20,Thermodynamic investigations on the growth of CuAlO$_2$ delafossite crystals,"Simultaneous differential thermal analysis (DTA) and thermogravimetric (TG)
+measurements with copper oxide/aluminum oxide mixtures were performed in
+atmospheres with varying oxygen partial pressures and with crucibles made of
+different materials. Only sapphire and platinum crucibles proved to be stable
+under conditions that are useful for the growth of CuAlO$_2$ delafossite single
+crystals. Then the ternary phase diagram Al$_2$O$_3$-CuO-Cu and its isopleth
+section Cu$_2$O-Al$_2$O$_3$ were redetermined. Millimeter sized crystals could
+be obtained from copper oxide melts with 1-2 mol % addition of aluminum oxide
+that are stable in platinum crucibles held in oxidizing atmosphere containing
+15-21 % oxygen.",1709.06776v1
+2017-11-09,Graphene oxide dielectric permittivity at GHz and its applications for wireless humidity sensing,"Graphene oxide relative dielectric permittivity, both its real and imaginary
+parts, have been measured under various humidity conditions at GHz. It is
+demonstrated that the relative dielectric permittivity increases with
+increasing humidity due to water uptake. This electrical property of graphene
+oxide was used to create a battery-free wireless radio-frequency identification
+(RFID) humidity sensor by coating printed graphene antenna with the graphene
+oxide layer. The resonance frequency as well as the backscattering phase of
+such graphene oxide/graphene antenna become sensitive to the surrounding
+humidity and can be detected by the RFID reader. This enables batteryless
+wireless monitoring of the local humidity with digital identification attached
+to any location or item and paves the way for low-cost efficient sensors for
+Internet of Things applications.",1711.03435v1
+2017-11-15,NC-AFM and XPS Investigation of Single-crystal Surfaces Supporting Cobalt (III) Oxide Nanostructures Grown by a Photochemical Method,"The work of this thesis comprises extensive Noncontact Atomic Force
+Microscopy (NC-AFM) characterization of clean metal-oxide (YSZ(100)/(111) and
+MgO(100)) and graphitic (HOPG) supports as templates for the novel,
+photochemically induced nucleation of cobalt oxide nanostructures, particularly
+Cobalt (III) Oxide. The nanostructure-support surfaces were also studied by
+X-ray Photoelectron Spectroscopy (XPS) to verify the nature of the supported
+cobalt oxide and to corroborate the surface topographic and phase NC-AFM data.
+Heteroepitaxial growth of Co2O3 nanostructures proves to exhibit a variety of
+different growth modes based on the structure of the support surface. On this
+basis, single-crystal support surfaces ranging from nonpolar to polar and
+atomically flat to highly defective and reactive were chosen, again, yielding
+numerous substrate-nanostructure interactions that could be probed by
+high-performance surface science techniques.",1711.09971v1
+2018-06-07,Idiosyncratic Approach to Visualize Degradation of Black Phosphorus,"Black Phosphorus (BP) is an excellent material for post graphene era due to
+its layer dependent band gap, high mobility and high Ion/Ioff. However, its
+poor stability in ambient poses a great challenge in its practical and
+long-term usage. Optical visualization of oxidized BP is the key and foremost
+step for its successful passivation from the ambience. Here, we have done a
+systematic study of the oxidation of BP and developed a technique to optically
+identify the oxidation of BP using Liquid Crystal (LC). Interestingly we found
+that rapid oxidation of thin layers of BP makes them disappear and can be
+envisaged by using the alignment of LC. The molecular dynamics simulations also
+proved the preferential alignment of LC on oxidized BP. We believe that this
+simple technique will be effective in passivation efforts of BP and will enable
+it for exploitation of its properties in the field of electronics.",1806.02872v1
+2018-06-30,Nanoscale compositional evolution in complex oxide based resistive memories,"Functional oxides based resistive memories are recognized as potential
+candidate for the next-generation high density data storage and neuromorphic
+applications. Fundamental understanding of the compositional changes in the
+functional oxides is required to tune the resistive switching characteristics
+for enhanced memory performance. Herein, we present the micro/nano-structural
+and compositional changes induced in a resistive oxide memory during resistive
+switching. Oxygen deficient amorphous chromium doped strontium titanate
+(Cr:$a$-SrTiO$_{3-x}$) based resistance change memories are fabricated in a
+Ti/Cr:$a$-SrTiO$_{3-x}$ heterostructure and subjected to different biasing
+conditions to set memory states. Transmission electron microscope based
+cross-sectional analyses of the memory devices in different memory states shows
+that the micro/nano-structural changes in amorphous complex oxide and
+associated redox processes define the resistive switching behavior. These
+experimental results provide insights and supporting material for Ref. [1].",1807.00185v1
+2018-07-07,Oxygen Potential Transition in Mixed Conducting Oxide Electrolyte,"It is generally assumed that oxygen potential in a thin oxide electrolyte
+follows a linear distribution between electrodes. Jacobsen and Mogensen have
+shown, however, that this is not the case for thin zirconia membranes in solid
+oxide electrochemical cells. Here we demonstrate that there is a ubiquitous
+oxygen potential transition rooted in the p-type/n-type transition of
+electronic conductivity inside mixed conducting oxides, and that the transition
+is extremely sensitive to electrode potential and current density. It is also
+remarkably sensitive to the conductivity ratio of electrons and holes, as well
+as their association with lattice oxygens and vacancies, which tends to
+increase the oxygen flow. Direct evidence of a sharp oxygen potential
+transition has been found in an equally sharp grain size transition in
+electrically loaded zirconia. More broadly speaking, the oxygen potential
+transition is akin to a first-order phase transition. Therefore, it will suffer
+interface instability, especially in high-current-density devices. These
+findings provide new opportunities to understand several disparate observations
+in the literature, from microstructural degradation and stress distribution in
+solid oxide fuel/electrolyzer cells, to field-assisted sintering, to conducting
+filaments in resistance memory, to dendrite formation in electrochemical cells.",1807.02704v1
+2018-08-23,Oxide Heterostructures from a Realistic Many-Body Perspective,"Oxide heterostructures are a new class of materials by design, that open the
+possibility for engineering challenging electronic properties, in particular
+correlation effects beyond an effective single-particle description. This short
+review tries to highlight some of the demanding aspects and questions,
+motivated by the goal to describe the encountered physics from first
+principles. The state-of-the-art methodology to approach realistic many-body
+effects in strongly correlated oxides, the combination of density functional
+theory with dynamical mean-field theory, will be briefly introduced. Discussed
+examples deal with prominent Mott-band- and band-band-insulating type of oxide
+heterostructures, where different electronic characteristics may be stabilized
+within a single architectured oxide material.",1808.07672v1
+2019-02-12,Deal-Grove Oxidation and Nanoparticle Adhesion - an AFM Study,"We study the formation of nanometer thick oxide layers around nanoparticles
+(plateaus) in a wet nitrogen environment over 32 days. We determine both the
+plateau height and the lateral force needed to remove the particles with an
+atomic force microscope (AFM). The height is well described by the Deal-Grove
+model for a thermally activated diffusion limited oxidation process.
+Furthermore, we observe that height and force appear to be correlated
+suggesting that the rise in adhesion forces is mainly governed by an oxidation
+process. Since the plateaus are the result of a change in the chemical
+structure, the surface remains permanently altered even after the removal of
+the nanoparticles. This observation is of great importance for many
+applications requiring smooth silicon surfaces, such as photolithography, where
+small contamination can cause the observed oxidation process and significantly
+increase the surface roughness.",1902.04494v1
+2019-02-14,Coherent optical modulation of partially mode-locked fiber laser based on coherent population oscillation in reduced oxide graphene,"Optical control of graphene-based photonic devices and systems has been under
+extensive explorations, nevertheless, the requirement of high power pump laser
+due to incoherent modulation makes those schemes low efficient. Here, we
+demonstrate coherent manipulation of the operating states of partially
+mode-locked fiber laser based on coherent population oscillation in reduced
+graphene oxide for the first time. We couple a much weaker continuous wave
+laser into the resonator operating with parametric instability state, and
+observe significant depression/enhancement of the sidebands when the coherent
+population oscillation conditions are satisfied. Besides, significant
+depression of partially mode-locked fiber laser is achieved. The experimental
+results reveal that the coherent population oscillation in reduced graphene
+oxide is highly effective in manipulating mode-locked fiber laser system, and
+the induced phase variation is highly asymmetrical. The discovery of coherent
+population oscillation in reduced graphene oxide facilitates coherent optical
+modulation of reduced graphene oxide-based photonic devices and systems with a
+much weaker controlling laser.",1902.05901v1
+2019-03-13,Nanoscale Oxygen Defect Gradients in the Actinide Oxides,"Oxygen defects govern the behavior of a range of materials spanning
+catalysis, quantum computing, and nuclear energy. Understanding and controlling
+these defects is particularly important for the safe use, storage, and disposal
+of actinide oxides in the nuclear fuel cycle, since their oxidation state
+influences fuel lifetimes, stability, and the contamination of groundwater.
+However, poorly understood nanoscale fluctuations in these systems can lead to
+significant deviations from bulk oxidation behavior. Here we describe the first
+use of aberration-corrected scanning transmission electron microscopy and
+electron energy loss spectroscopy to resolve changes in the local oxygen defect
+environment in UO$_2$ surfaces. We observe large image contrast and spectral
+changes that reflect the presence of sizable gradients in interstitial oxygen
+content at the nanoscale, which we quantify through first principles
+calculations and image simulations. These findings reveal an unprecedented
+level of excess oxygen incorporated in a complex near-surface spatial
+distribution, offering new insight into defect formation pathways and kinetics
+during UO$_2$ oxidation.",1903.05741v1
+2019-03-14,Nano-engineering of electron correlation in oxide superlattices,"Oxide heterostructures and superlattices have attracted a great deal of
+attention in recent years owing to the rich exotic properties encountered at
+their interfaces. We focus on the potential of tunable correlated oxides by
+investigating the spectral function of the prototypical correlated metal SrVO3,
+using soft x-ray absorption spectroscopy (XAS) and resonant inelastic soft
+x-ray scattering (RIXS) to access both unoccupied and occupied electronic
+states, respectively. We demonstrate a remarkable level of tunability in the
+spectral function of SrVO3 by varying its thickness within the SrVO3/SrTiO3
+superlattice, showing that the effects of electron correlation can be tuned
+from dominating the energy spectrum in a strongly correlated Mott-Hubbard
+insulator, towards a correlated metal. We show that the effects of
+dimensionality on the correlated properties of SrVO3 are augmented by
+interlayer coupling, yielding a highly flexible correlated oxide that may be
+readily married with other oxide systems.",1903.05911v1
+2020-03-31,Conductive Domain Walls in Non-Oxide Ferroelectrics Sn2P2S6,"The conductive domain wall (CDW) is extensively investigated in
+ferroelectrics, which can be considered as a quasi-two-dimensional
+reconfigurable conducting channel embedded into an insulating material.
+Therefore, it is highly important for the application of ferroelectric
+nanoelectronics. Hitherto, most CDW investigations are restricted in oxides,
+and limited work has been reported in non-oxides to the contrary. Here, by
+successfully synthesizing the non-oxide ferroelectric Sn2P2S6 single crystal,
+we observed and confirmed the domain wall conductivity by using different
+scanning probe techniques which origins from the nature of inclined domain
+walls. Moreover, the domains separated by CDW also exhibit distinguishable
+electrical conductivity due to the interfacial polarization charge with
+opposite signs. The result provides a novel platform for understanding
+electrical conductivity behavior of the domains and domain walls in non-oxide
+ferroelectrics.",2003.13927v1
+2020-08-13,Where are the Extrasolar Mercuries?,"We utilize observations of 16 white dwarf stars to calculate and analyze the
+oxidation states of the parent bodies accreting onto the stars. Oxygen
+fugacity, a measure of overall oxidation state for rocks, is as important as
+pressure and temperature in determining the structure of a planet. We find that
+most of the extrasolar rocky bodies formed under oxidizing conditions, but
+approximately 1/4 of the polluted white dwarfs have compositions consistent
+with more reduced parent bodies. The difficulty in constraining the oxidation
+states of relatively reduced bodies is discussed and a model for the
+time-dependent evolution of the apparent oxygen fugacity for a hypothetical
+reduced body engulfed by a WD is investigated. Differences in diffusive fluxes
+of various elements through the WD envelope yield spurious inferred bulk
+elemental compositions and oxidation states of the accreting parent bodies
+under certain conditions. The worst case for biasing against detection of
+reduced bodies occurs for high effective temperatures. For moderate and low
+effective temperatures, evidence for relatively reduced parent bodies is
+preserved under most circumstances for at least several characteristic
+lifetimes of the debris disk.",2008.05992v1
+2020-11-17,Orbital Rashba effect in surface oxidized Cu film,"Recent experimental observation of unexpectedly large current-induced
+spin-orbit torque in surface oxidized Cu on top of a ferromagnet suggested a
+possible role of the orbital Rashba effect (ORE). With this motivation, we
+investigate the ORE from first principles by considering an oxygen monolayer on
+top of a Cu(111) film. We show that surface oxidization of Cu film leads to
+gigantic enhancement of the ORE for states near the Fermi surface. The
+resulting chiral orbital texture in the momentum space is exceptionally strong,
+reaching $\sim 0.5\hbar$ in magnitude. We find that resonant hybridization
+between O $p$-states and Cu $d$-states is responsible for the emergence of the
+ORE. We demonstrate that application of an external electric field generates
+huge orbital Hall current, which is an order of magnitude larger than the spin
+Hall current found in heavy metals. This implies that ""orbital torque""
+mechanism may be significant in surface oxidized Cu/ferromagnet structures. It
+also encourages experimental verification of the orbital texture in surface
+oxidized Cu through optical measurements such as angle-resolved photoemission
+spectroscopy.",2011.08601v1
+2021-05-22,Scaling Theory of Two-Dimensional Field Effect Transistors,"We present a scaling theory of two-dimensional (2D) field effect transistors
+(FETs). For devices with channel thickness less than 4 nm, the device
+electrostatics is dominated by the physical gate oxide thickness and not the
+effective oxide thickness. Specifically, for symmetric double gate (DG) FETs
+the scale length ({\Lambda}) varies linearly with the gate oxide
+thickness(t_{ox}) as {\Lambda} ~ 3/4t_{ox}. The gate oxide dielectric
+permittivity and the semiconductor channel thickness do not affect the device
+electrostatics for such device geometries. For an asymmetric device such as
+single gate (SG) FETs, the fringing fields have a second order effect on the
+scale length. However, like symmetric DG FETs, the scale length in asymmetric
+FETs is also ultimately limited by the physical gate oxide thickness. We
+compare our theoretical predictions for scaled monolayer MoS2 DG FETs.",2105.10791v1
+2021-10-09,Deciphering the role of Al$_2$O$_3$ formed during isothermal oxidation in a dual-phase AlCoCrFeNi$_{2.1}$ Eutectic High-Entropy Alloy,"In recent times,there has been a significant volume of work on Eutectic High
+Entropy Alloys (EHEAs) owing to their remarkable castability combined with
+excellent mechanical properties,which aids in clearing obstacles for their
+technological applications. One of the most common EHEAs,which has been of
+enormous interest at present, primarily owing to its solidification and tensile
+behavior, is AlCoCrFeNi$_{2.1}$. However,to aim for high-temperature
+applications,oxidation behaviour of material is one of the major aspects that
+needs to be extensively investigated.To this end,the present work aims to study
+the phases evolved during oxidation at elevated temperatures as high as 950 and
+1000$^\circ$C in AlCoCrFeNi$_{2.1}$ using XRD and also to determine the rate
+law followed for isothermal oxidation of this alloy at 950 and 1000$^\circ$C,in
+order to understand the role of Al$_2$O$_3$ phase formed during isothermal
+oxidation at 950 and 1000$^\circ$C.",2110.09222v1
+2021-11-01,Noble-Metal-Assisted Fast Interfacial Oxygen Migration with Topotactic Phase Transition in Perovskite Oxides,"Transition-metal perovskite oxides constitute a series of functional material
+systems for electronics, catalysis and energy-conversion processes, in which
+oxygen migration and evolution play a key role. However, the stable
+metal-oxygen (M-O) bond forms large energy barrier inhibiting ion diffusion.
+Therefore, seeking efficient and facile approaches to accelerate oxygen
+kinetics has become a significant issue. Here, the interaction (interfacial
+charge transfer and cooperative bonding) between noble metal (Pt, Ag) and
+perovskites oxide (SrCoO3-delta) is employed to weaken (M-O) bond and decrease
+the energy barrier of oxygen migration. Noble metal layers serving as oxygen
+pumps can continuously extract oxygen from oxide films to atmosphere. The
+temperature of topotactic phase transition from perovskite (SrCoO3) to
+brownmillerite (SrCoO2.5) is remarkably lowered from 200 K to room temperature.
+Furthermore, this approach can also be applied to SrFeO3 for similar topotactic
+phase reduction by moderate thermal activation. Our finding paves a promising
+and general pathway to achieve fast oxygen migration in perovskite oxides, with
+important application prospect in low-temperature electrodes and high-activity
+catalysis interface.",2111.00663v1
+2021-11-23,Eliminating Delocalization Error to Improve Heterogeneous Catalysis Predictions with Molecular DFT+U,"Approximate semi-local density functional theory (DFT) is known to
+underestimate surface formation energies yet paradoxically overbind adsorbates
+on catalytic transition-metal oxide surfaces due to delocalization error. The
+low-cost DFT+U approach only improves surface formation energies for early
+transition-metal oxides or adsorption energies for late transition-metal
+oxides. In this work, we demonstrate that this inefficacy arises due to the
+conventional usage of metal-centered atomic orbitals as projectors within
+DFT+U. We analyze electron density rearrangement during surface formation and O
+atom adsorption on rutile transition-metal oxides to highlight that a standard
+DFT+U correction fails to tune properties when the corresponding density
+rearrangement is highly delocalized across both metal and oxygen sites. To
+improve both surface properties simultaneously while retaining the simplicity
+of a single-site DFT+U correction, we systematically construct
+multi-atom-centered molecular-orbital-like projectors for DFT+U. We demonstrate
+this molecular DFT+U approach for tuning adsorption energies and surface
+formation energies of minimal two-dimensional models of representative early
+(i.e., TiO2) and late (i.e., PtO2) transition-metal oxides. Molecular DFT+U
+simultaneously corrects adsorption energies and surface formation energies of
+multi-layer models of rutile TiO2(110) and PtO2(110) to resolve the paradoxical
+description of surface stability and surface reactivity of semi-local DFT.",2111.11614v1
+2022-02-03,Tuning carrier density and phase transitions in oxide semiconductors using focused ion beams,"We demonstrate spatial modification of the optical properties of thin-film
+metal oxides, zinc oxide and vanadium dioxide as representatives, using a
+commercial focused ion beam (FIB) system. Using a Ga+ FIB and thermal
+annealing, we demonstrated variable doping of a band semiconductor, zinc oxide
+(ZnO), achieving carrier concentrations from 10^18 cm-3 to 10^20 cm-3. Using
+the same FIB without subsequent thermal annealing, we defect-engineered a
+correlated semiconductor, vanadium dioxide (VO2), locally modifying its
+insulator-to-metal transition (IMT) temperature by range of ~25 degrees C. Such
+area-selective modification of metal oxides by direct writing using a FIB
+provides a simple, mask-less route to the fabrication of optical structures,
+especially when multiple or continuous levels of doping or defect density are
+required.",2202.01777v3
+2022-02-22,Stabilization of Co oxide during oxygen evolution in alkaline media by the introduction of Mn oxide,"Improving the stability of electrocatalysts for the oxygen evolution reaction
+(OER) through materials design has received less attention than improving their
+catalytic activity. We explored the effect of Mn addition to a cobalt oxide for
+stabilizing the catalyst by comparing Na-containing CoOx and (Co0.7Mn0.3)Ox
+films electrodeposited in alkaline solution. The obtained disordered films were
+classified as layered oxides using X-ray absorption spectroscopy (XAS). The
+CoOx films showed a constant decrease in the catalytic activity during cycling,
+confirmed by oxygen detection, while that of (Co0.7Mn0.3)Ox slightly increased
+as measured by electrochemical metrics. These trends were rationalized based on
+XAS analysis of the metal oxidation states, which were Co2.8+ and Mn3.7+ near
+the surface after cycling. Thus, adding Mn to CoOx successfully stabilized the
+catalyst material and its activity during OER cycling. The development of
+stabilization approaches is essential to extend the durability of OER
+catalysts.",2202.10836v1
+2022-03-13,Mixed excitonic nature in water-oxidized BiVO$_4$ surfaces with defects,"BiVO$_4$ is a promising photocatalyst for efficient water oxidation, with
+surface reactivity determined by the structure of active catalytic sites.
+Surface oxidation in the presence of oxygen vacancies induces electron
+localization, suggesting an atomistic route to improve the charge transfer
+efficiency within the catalytic cycle. In this work, we study the effect of
+oxygen vacancies on the electronic and optical properties at BiVO$_4$ surfaces
+upon water oxidation. We use density functional theory and many-body
+perturbation theory to explore the change in the electronic and quasiparticle
+energy levels and to evaluate the electron-hole coupling as a function of the
+underlying structure. We show that while the presence of defects alters the
+atomic structure and largely modifies the wavefunction nature, leading to
+defect-localized states at the quasipatricle gap region, the optical
+excitations remain largely unchanged due to substantial hybridization of defect
+and non-defect electron-hole transitions. Our findings suggest that
+defect-induced surface oxidation supports improved electron transport, both
+through bound and tunable electronic states and via a mixed nature of the
+optical transitions, expected to reduce electron-hole defect trapping.",2203.06636v1
+2022-03-21,Thermodynamic descriptors to predict oxide formation in aqueous solutions,"We formulate the maximum driving force (MDF) parameter as a descriptor to
+capture the thermodynamic stability of aqueous surface scale creation over a
+range of environmental conditions. We use formation free energies, $\Delta_f
+G$s, sourced from high-throughput density functional theory (DFT) calculations
+and experimental databases to compute the maximum driving force for a wide
+variety of materials, including simple oxides, intermetallics, and alloys of
+varying compositions. We show how to use the MDF to describe trends in aqueous
+corrosion of nickel thin films determined from experimental
+linear-sweep-voltometry data. We also show how to account for subsurface
+oxidation behavior using depth-dependent effective chemical potentials. We
+anticipate this approach will increase overall understanding of oxide formation
+on chemically complex multielement alloys, where competing oxide phases can
+form during transient aqueous corrosion.",2203.11013v1
+2022-08-26,What is in a Name: Defining -High Entropy- Oxides,"High entropy oxides are emerging as an exciting new avenue to design highly
+tailored functional behaviors that have no traditional counterparts. Study and
+application of these materials are bringing together scientists and engineers
+from physics, chemistry, and materials science. The diversity of each of these
+disciplines comes with perspectives and jargon that may be confusing to those
+outside of the individual fields, which can result in miscommunication of
+important aspects of research. In this perspective, we provide examples of
+research and characterization taken from these different fields to provide a
+framework for classifying the differences between compositionally complex
+oxides, high entropy oxides, and entropy stabilized oxides, which is intended
+to bring a common language to this emerging area. We highlight the critical
+importance of understanding a materials crystallinity, composition, and mixing
+length scales in determining its true definition.",2208.12709v2
+2022-09-12,Origin of superconductivity in hole doped SrBiO3 bismuth oxide perovskite from parameter-free first-principles simulations,"The recent discovery nickel oxides superconductors have highlighted the
+importance of first-principles simulations for understanding the formation of
+the bound electrons at the core of superconductivity. Nevertheless,
+superconductivity in oxides is often ascribed to strong electronic correlation
+effects that Density Functional Theory (DFT) cannot properly take into account,
+thereby disqualifying this technique. Being isostructural to nickel oxides,
+Sr1-xKxBiO3 superconductors form an ideal testbed for unveiling (i) the lowest
+theory level needed to model complex superconductors and (ii) the underlying
+pairing mechanism yielding superconductivity. Here I show that parameter-free
+DFT simulations capture all the experimental features and related quantities of
+Sr1-xKxBiO3 superconductors, encompassing the prediction of an insulating to
+metal phase transition upon increasing the K doping content and of an
+electron-phonon coupling constant of 1.22 in sharp agreement with the
+experimental value of 1.3 +/- 0.2. Proximity of a disproportionated phase is
+further demonstrated to be a prerequisite for superconductivity in bismuthates.
+This work highlights that appropriately executed DFT is a sufficient platform
+for studying superconductivity in complex oxides.",2209.05198v1
+2022-09-16,Epitaxy of hexagonal ABO$_3$ quantum materials,"Hexagonal $AB$O$_3$ oxides ($A$, $B$ = cation) are a rich materials class for
+realizing novel quantum phenomena. Their hexagonal symmetry, oxygen trigonal
+bipyramid coordination and quasi-two dimensional layering give rise to
+properties distinct from those of the cubic $AB$O$_3$ perovskites. As bulk
+materials, most of the focus in this materials class has been on the rare earth
+manganites, $R$MnO$_3$ ($R$ = rare earth); these materials display coupled
+ferroelectricity and antiferromagnetic order. In this review, we focus on the
+thin film manifestations of the hexagonal $AB$O$_3$ oxides. We cover the
+stability of the hexagonal oxides and substrates which can be used to template
+the hexagonal structure. We show how the thin film geometry not only allows for
+further tuning of the bulk-stable manganites but also the realization of
+metastable hexagonal oxides such as the $R$FeO$_3$ that combine
+ferroelectricity with weak ferromagnetic order. The thin film geometry is a
+promising platform to stabilize additional metastable hexagonal oxides to
+search for predicted high-temperature superconductivity and topological phases
+in this materials class.",2209.08006v1
+2023-01-07,Visible-light photocatalytic oxygen production on a high-entropy oxide by multiple-heterojunction introduction,"High-entropy oxides (HEOs), as multi-component ceramics with high
+configurational entropy, have been of recent interest due to their attractive
+properties including photocatalytic activity for H2 production and CO2
+conversion. However, the photocatalytic activity of HEOs is still limited to
+ultraviolet light. In this study, to achieve visible-light-driven
+photocatalysis, 10 different heterojunctions were simultaneously introduced in
+the Ti-Zr-Nb-Ta-W-O system. The oxide, which was synthesized by a high-pressure
+torsion method and oxidation, successfully produced oxygen from water under
+visible light without co-catalyst addition. The photocatalytic performance was
+attributed to high visible-light absorption, narrow bandgap, appropriate band
+structure, presence of multiple heterojunctions and accordingly easy
+electron-hole separation and slow recombination. These results not only show
+the potential of high-entropy oxides as new visible-light-active
+photocatalysts, but also introduce the multiple-heterojunction introduction as
+a strategy to achieve photocatalysis under visible light.",2301.05016v1
+2023-04-27,Wavelength Dependent Nonlinear Spectroscopic Study of Third Harmonic Generation Probed by Rotational Maker Fringes Method,"Efficient third-order nonlinearities of the Zinc Oxide and Al-doped Zinc
+Oxide were studied by Third Harmonic Generation (Third Harmonic Generation)
+Maker fringes to establish the effect Aluminum of Aluminum doping(Al-doping) on
+the cubic nonlinearities. The addition of the Al-dopant to the Zinc Oxide
+crystal structure results in changes that affected the optical and nonlinear
+characteristics. Presented results indicate that magnitude of the third-order
+nonlinear susceptibility tensor was enhanced at single experimental
+wavelengths, however, across the broadband experimental spectrum the effect of
+Al-doping remained relatively constant. The observed enhancement of third-order
+nonlinearity was purely from the bound electronic response and the observation
+is attributed to increased charge carriers and spontaneous polarization in the
+Zinc Oxide and Al-doped Zinc Oxide crystal structure.",2304.14523v1
+2023-04-29,The Combination of Metal Oxides as Oxide Layers for RRAM and Artificial Intelligence,"Resistive random-access memory (RRAM) is a promising candidate for
+next-generation memory devices due to its high speed, low power consumption,
+and excellent scalability. Metal oxides are commonly used as the oxide layer in
+RRAM devices due to their high dielectric constant and stability. However, to
+further improve the performance of RRAM devices, recent research has focused on
+integrating artificial intelligence (AI). AI can be used to optimize the
+performance of RRAM devices, while RRAM can also power AI as a hardware
+accelerator and in neuromorphic computing. This review paper provides an
+overview of the combination of metal oxides-based RRAM and AI, highlighting
+recent advances in these two directions. We discuss the use of AI to improve
+the performance of RRAM devices and the use of RRAM to power AI. Additionally,
+we address key challenges in the field and provide insights into future
+research directions",2305.00166v1
+2023-06-08,Iron Oxide Nanoparticles as a Contrast Agent for Synchrotron Imaging of Sperm,"Fast phase-contrast imaging offered by modern synchrotron facilities opens
+the possibility of imaging dynamic processes of biological material such as
+cells. Cells are mainly composed of carbon and hydrogen, which have low X-ray
+attenuation, making cell studies with X-ray tomography challenging. At specific
+low energies, cells provide contrast, but cryo-conditions are required to
+protect the sample from radiation damage. Thus, non-toxic labelling methods are
+needed to prepare living cells for X-ray tomography at higher energies. We
+propose using iron oxide nanoparticles due to their proven compatibility in
+other biomedical applications. We show how to synthesize and attach iron oxide
+nanoparticles and demonstrate that cell-penetrating peptides facilitate iron
+oxide nanoparticle uptake into sperm cells. We show results from the TOMCAT
+Nanoscope (Swiss Light Source), showing that iron oxide nanoparticles allow the
+heads and midpiece of fixed sperm samples to be reconstructed from X-ray
+projections taken at 10 keV.",2309.03908v1
+2023-10-12,Localization of vibrational modes in high-entropy oxides,"The recently-discovered high-entropy oxides offer a paradoxical combination
+of crystalline arrangement and high disorder. They differ qualitatively from
+established paradigms for disordered solids such as glasses and alloys. In
+these latter systems, it is well known that disorder induces localized
+vibrational excitations. In this article, we explore the possibility of
+disorder-induced localization in (MgCoCuNiZn)O, the prototypical high-entropy
+oxide with rock-salt structure. To describe phononic excitations, we model the
+interatomic potentials for the cation-oxygen interactions by fitting to the
+physical properties of the parent binary oxides. We validate our model against
+the experimentally determined crystal structure, bond lengths, and optical
+conductivity. The resulting phonon spectrum shows wave-like propagating modes
+at low energies and localized modes at high energies. Localization is reflected
+in signatures such as participation ratio and correlation amplitude. Finally,
+we explore the possibility of increased mass disorder in the oxygen sublattice.
+Admixing sulphur or tellurium atoms with oxygen enhances localization. It even
+leads to localized modes in the middle of the spectrum. Our results suggest
+that high-entropy oxides are a promising platform to study Anderson
+localization of phonons.",2310.08668v1
+2023-10-21,Advances in Complex Oxide Quantum Materials Through New Approaches to Molecular Beam Epitaxy,"Molecular beam epitaxy (MBE), a workhorse of the semiconductor industry, has
+progressed rapidly in the last few decades in the development of novel
+materials. Recent developments in condensed matter and materials physics have
+seen the rise of many novel quantum materials that require ultra-clean and
+high-quality samples for fundamental studies and applications. Novel
+oxide-based quantum materials synthesized using MBE have advanced the
+development of the field and materials. In this review, we discuss the recent
+progress in new MBE techniques that have enabled synthesis of complex oxides
+that exhibit ""quantum"" phenomena, including superconductivity and topological
+electronic states. We show how these techniques have produced breakthroughs in
+the synthesis of 4d and 5d oxide films and heterostructures that are of
+particular interest as quantum materials. These new techniques in MBE offer a
+bright future for the synthesis of ultra-high quality oxide quantum materials.",2310.13902v1
+2024-03-02,"A peridynamic investigation of particle oxidation, size and material during cold-spray","Cold spray technology, distinguished by its unique ability to deposit
+particles in a solid state, offers unparalleled potential for applications such
+as coating, repair, and additive manufacturing. In this research, we employed a
+peridynamic modeling approach to systematically analyze the effects of key
+powder features on deposit properties. Notably, our model incorporates the
+explicit modeling of nanometer-sized oxide layers, providing a more accurate
+representation of real-world conditions. We assessed the influence of
+parameters such as particle size, oxidation conditions, and material type on
+crucial deposition indicators like critical velocity and compression ratio. Our
+results demonstrated excellent agreement with reported experimental data,
+affirming the effectiveness of the proposed numerical framework. Specifically,
+our findings highlighted that, for a given impact velocity, smaller particles,
+thicker oxide layers, and harder materials contribute to limited oxide removal
+and a decreased likelihood of successful adhesion. Additionally, we present a
+predictive framework that establishes a correlation between particle size and
+critical velocity, providing valuable insights for optimizing cold spray
+deposition parameters. This innovative approach not only enhances our
+understanding of the intricate interplay between powder features and deposit
+properties but also paves the way for a more efficient and cost-effective
+optimization process in cold spray applications.",2403.01311v1
+2024-03-18,Theoretical Study on Optoelectronic properties of Layered In2O3 and Ga2O3,"Composite oxides have been indeed proved to be valuable materials in
+optoelectronic applications. The combination of indium oxide and gallium oxide
+and other materials can lead to enhanced optical and electronic properties,
+making them suitable for a variety of optoelectronic devices. Meticulous
+analysis of the various optical properties helped to draw conclusions about the
+heterostructure of Indium and Gallium oxide and its use as a suitable
+semiconducting material in the medium bandgap range. The density of states and
+the band structure have been obtained from the density functional theory
+calculations. Real frequency phonon density of states supports dynamical
+stability of the crystal structure. A favorable energy band gap is achieved in
+the visible region of the spectrum, indicating that this mixed oxide is well
+suited for optoelectronic devices such as LEDs and solar cells.",2403.11619v1
+2004-05-15,Ordinary Chondrite Formation from two Components: Implied Connection to Planet Mercury,"Major element fractionation among chondrites has been discussed for decades
+as ratios relative to Si or Mg. Expressing ratios relative to Fe leads to a new
+relationship admitting the possibility that ordinary chondrite meteorites are
+derived from two components: one is a relatively undifferentiated, primitive
+component, oxidized like the CI or C1 chondrites; the other is a somewhat
+differentiated, planetary component, with oxidation state like the reduced
+enstatite chondrites. Such a picture would seem to explain for the ordinary
+chondrites, their major element compositions, their intermediate states of
+oxidation, and their ubiquitous deficiencies of refractory siderophile
+elements. I suggest that the planetary component of ordinary chondrite
+formation consists of planet Mercury's missing complement of elements.",0405298v1
+1996-08-01,Collective rotations in oxides,"Based on bond arguments, a Hamiltonian is introduced to describe the
+fundamental physics of the collective rotations of oxygen atoms in oxides.
+Values for the relevant material parameters are estimated for silica and Cu
+oxides. Zero-temperature phase diagrams are presented; the different phases and
+associated transitions are characterized. Phases with non-phononic excitations
+are found.",9608002v1
+1997-05-30,Polar Jahn-Teller Centers and Isotope Effect in Copper Oxide high-T_c-Superconductors,"The $CuO_4$-cluster based copper oxides are considered as generalized quantum
+lattice bose-gas or a system of the local singlet bosons moving in a lattice of
+the hole Jahn-Teller centers $[CuO_{4}^{5-}]_{JT}$. The model is illustrated by
+the qualitative and quantitative description of the various peculiarities of an
+isotope shift (IS-) effect in a series of 123-like oxides.",9705306v1
+1999-03-10,Large Thermopower in a Layered Oxide NaCo_2O_4,"A transition-metal oxide NaCo_2O_4 is a layered oxide in which CoO_2 and Na
+alternately stack along the c axis. Recently we have found that this compound
+shows unusually large thermopower with low resistivity, which is comparable to
+those of Bi_2Te_3. The negative transverse magnetoresistance and the strongly
+temperature-dependent Hall coefficient suggest that electron correlation
+dominates the conduction mechanism in NaCo_2O_4.",9903162v1
+2002-02-19,Production of a hafnium silicate dielectric layer for use as a gate oxide by solid-state reaction,"The formation of hafnium silicate films (HfSixOy) for use as gate oxides with
+large dielectric constant by solid state reaction of Hf metal and SiO2 was
+investigated. Thin, fully reacted silicate films could be formed, and were
+thermally stable in vacuum to temperatures in excess of 800 C. The interface
+between a hafnium silicate layer and the silicon substrate was shown to be
+stable against SiO2 formation. The results suggest a new processing route for
+production of a gate insulator having low equivalent oxide thickness.",0202328v1
+2002-06-28,"Electron localization : band-by-band decomposition, and application to oxides","Using a plane wave pseudopotential approach to density functional theory we
+investigate the electron localization length in various oxides. For this
+purpose, we first set up a theory of the band-by-band decomposition of this
+quantity, more complex than the decomposition of the spontaneous polarization
+(a related concept), because of the interband coupling. We show its
+interpretation in terms of Wannier functions and clarify the effect of the
+pseudopotential approximation. We treat the case of different oxides: BaO,
+$\alpha$-PbO, BaTiO$_3$ and PbTiO$_3$. We also investigate the variation of the
+localization tensor during the ferroelectric phase transitions of BaTiO$_3$ as
+well as its relationship with the Born effective charges.",0206580v1
+2004-05-31,Electron-phonon interaction enhanced by antiferromagnetic and superconducting fluctuations in cuprate oxide superconductors,"An electron-phonon interaction arising from the modulation of the
+superexchange interaction by phonons is studied within the theoretical
+framework of Kondo lattices. It is relevant in strongly correlated electron
+liquids in cuprate oxide superconductors, which lie in the vicinity of the
+Mott-Hubbard metal-insulator transition. It is enhanced by antiferromagnetic
+and superconducting fluctuations, which are developed mainly because of the
+superexchange interaction. When the enhancement of the electron-phonon
+interaction is large enough, it can explain the softening of phonons and kinks
+in the quasiparticle dispersion in cuprate oxide superconductors. However, the
+superexchange interaction itself must be mainly responsible for the formation
+of Cooper pairs.",0405703v1
+2006-01-25,The energetics of water on oxide surfaces by quantum Monte Carlo,"Density functional theory (DFT) is widely used in surface science, but gives
+poor accuracy for oxide surface processes, while high-level quantum chemistry
+methods are hard to apply without losing basis-set quality. We argue that
+quantum Monte Carlo techniques allow these difficulties to be overcome, and we
+present diffusion Monte Carlo results for the formation energy of the MgO(001)
+surface and the adsorption energy of H$_2$O on this surface, using periodic
+slab geometry. The results agree well with experiment. We note other oxide
+surface problems where these techniques could yield immediate progress.",0601572v2
+2006-03-28,Tungsten oxide nanowire growth by chemically-induced strain,"We have investigated the formation of tungsten oxide nanowires under
+different CVD conditions. We find that exposure of oxidized tungsten films to
+hydrogen and methane at 900C leads to the formation of a dense array of
+typically 10 nm diameter nanowires. Structural and chemical analysis shows that
+the wires are crystalline WO3. We propose a chemically-driven whisker growth
+mechanism in which interfacial strain associated with the formation of tungsten
+carbide stimulates nanowire growth. This might be a general concept, applicable
+also in other nanowire systems.",0603746v1
+2006-04-09,MgB2 tunnel junctions with native or thermal oxide barriers,"MgB2 tunnel junctions (MgB2/barrier/MgB2) were fabricated using a native
+oxide grown on the bottom MgB2 film as the tunnel barrier. Such barriers
+therefore survive the deposition of the second electrode at 300oC, even over
+junction areas of ~1 mm2. Studies of such junctions, and those of the type
+MgB2/native or thermal oxide/metal (Pb, Au, or Ag) show that tunnel barriers
+grown on MgB2 exhibit a wide range of barrier heights and widths.",0604229v1
+2007-02-09,X-ray photoemission study of CoFeB/MgO thin film bi-layers,"We present results from an X-ray photoemission spectroscopy (XPS) study of
+CoFeB/MgO bi-layers where we observe process-dependent formation of B, Fe, and
+Co oxides at the CoFeB/MgO interface due to oxidation of CoFeB during MgO
+deposition. Vacuum annealing reduces the Co and Fe oxides but further
+incorporates B into the MgO forming a composite MgBxOy layer. Inserting an Mg
+layer between CoFeB and MgO introduces an oxygen sink, providing increased
+control over B content in the barrier.",0702232v1
+2003-12-22,Cosmological billiards and oxidation,"We show how the properties of the cosmological billiards provide useful
+information (spacetime dimension and $p$-form spectrum) on the oxidation
+endpoint of the oxidation sequence of gravitational theories. We compare this
+approach to the other available methods: $GL(n,R)$ subgroups and the
+superalgebras of dualities.",0312251v2
+2007-04-29,Pinned Low Energy Electronic Excitation in Metal Exchanged Vanadium Oxide Nanoscrolls,"We measured the optical properties of mixed valent vanadium oxide nanoscrolls
+and their metal exchanged derivatives in order to investigate the charge
+dynamics in these compounds. In contrast to the prediction of a metallic state
+for the metal exchanged derivatives within a rigid band model, we find that the
+injected charges in Mn$^{2+}$ exchanged vanadium oxide nanoscrolls are pinned.
+A low-energy electronic excitation associated with the pinned carriers appears
+in the far infrared and persists at low temperature, suggesting that the
+nanoscrolls are weak metals in their bulk form, dominated by inhomogeneous
+charge disproportionation and Madelung energy effects.",0704.3861v1
+2007-07-23,Chemical nanomachining of silicon by gold-catalyzed oxidation,"A chemical nanomachining process for the rapid, scalable production of
+nanostructure assemblies from silicon-on-insulator is demonstrated. The process
+is based on the spontaneous, local oxidation of Si induced by Au, which is
+selectively evaporated onto the Si surface. The Au-catalyzed oxide forms a
+pattern that serves as a robust mask for the underlying Si, enabling the use of
+simple wet chemistry to sculpt arrays of nanostructures of diverse shapes
+including rings, pillars, wires, and nanopores. The remarkable simplicity of
+this chemical nanomachining process makes it widely accessible as an enabling
+technique for applications from photonics to biotechnology.",0707.3307v1
+2007-08-31,Phase stability of hafnium oxide and zirconium oxide on silicon substrate,"Phase stabilities of Hf-Si-O and Zr-Si-O have been studied with
+first-principles and thermodynamic modeling. From the obtained thermodynamic
+descriptions, phase diagrams pertinent to thin film processing were calculated.
+We found that the relative stability of the metal silicates with respect to
+their binary oxides plays a critical role in silicide formation. It was
+observed that both the HfO$_2$/Si and ZrO$_2$/Si interfaces are stable in a
+wide temperature range and silicide may form at low temperatures, partially at
+the HfO$_2$/Si interface.",0708.4356v1
+2008-04-30,Crystal chemical simulation of superconductors on the basis of oxide and intermetallic layers,"Simulation of 'hybrid' superconductors of 3d-, 4d- and 5d-transition elements
+consisting of two different superconducting fragments located between
+positively charged ions planes - B'O2 oxide planes and B2C2 intermetallic
+layers - has been performed on the basis of the structure of Sr2Mn3As2O2
+(A2(B2C2)(B'O2)). The oxide planes are similar to those of CuO2 in
+high-temperature superconducting cuprates while the intermetallic layers - to
+those of Ni2B2 in low-temperature superconducting borocarbides RNi2B2C and
+Fe2As2 layers in high-temperature superconducting oxypnictides RFeAsO1-xFx.",0804.4763v2
+2008-08-13,Coreless Terrestrial Exoplanets,"Differentiation in terrestrial planets is expected to include the formation
+of a metallic iron core. We predict the existence of terrestrial planets that
+have differentiated but have no metallic core--planets that are effectively a
+giant silicate mantle. We discuss two paths to forming a coreless terrestrial
+planet, whereby the oxidation state during planetary accretion and
+solidification will determine the size or existence of any metallic core. Under
+this hypothesis, any metallic iron in the bulk accreting material is oxidized
+by water, binding the iron in the form of iron oxide into the silicate minerals
+of the planetary mantle. The existence of such silicate planets has
+consequences for interpreting the compositions and interior density structures
+of exoplanets based on their mass and radius measurements.",0808.1908v1
+2008-11-21,Si3N4 single-crystal nanowires grown from silicon micro and nanoparticles near the threshold of passive oxidation,"A simple and most promising oxide-assisted catalyst-free method is used to
+prepare silicon nitride nanowires that give rise to high yield in a short time.
+After a brief analysis of the state of the art, we reveal the crucial role
+played by the oxygen partial pressure: when oxygen partial pressure is slightly
+below the threshold of passive oxidation, a high yield inhibiting the formation
+of any silica layer covering the nanowires occurs and thanks to the synthesis
+temperature one can control nanowire dimensions.",0811.3575v1
+2009-01-25,Sketching the Theory of Copper Oxide High Temperature Superconductivity,"The role of the anti-bonding state in the electron correlations in Copper
+Oxide HTSC is analyzed. Then the t-J Hamiltonian is used to establish the
+formation of the charge stripes in underdoped oxides. It is proposed that these
+stripes make up the boundaries between the two degenerate anti-ferromagnetic
+(AFM) states, and that they are a key factor in switching between these states.
+We also provide a theoretical expression for the charge driven AFM magnons that
+have been observed by Neutron scattering experiments. Finally, the double
+correlation theory is applied to the stripe phase of holes to result in the
+superconductive gap and in the ""pseudogap"".",0901.3896v2
+2009-02-10,Exchange bias in laterally oxidized Au/Co/Au nanopillars,"Au/Co/Au nanopillars fabricated by colloidal lithography of continuous
+trilayers exhibit and enhanced coercive field and the appearance of an exchange
+bias field with respect to the continuous layers. This is attributed to the
+lateral oxidation of the Co interlayer that appears upon disc fabrication. The
+dependence of the exchange bias field on the Co nanodots size and on the
+oxidation degree is analyzed and its microscopic origin clarified by means of
+Monte Carlo simulations based on a model of a cylindrical dot with lateral
+core/shell structure.",0902.1687v1
+2009-08-21,Structural and Electronic Properties of Oxidized Graphene,"We have systematically investigated the effect of oxidation on the structural
+and electronic properties of graphene based on first-principles calculations.
+Energetically favorable atomic configurations and building blocks are
+identified, which contain epoxide and hydroxyl groups in close proximity with
+each other. Different arrangements of these units yield an LDA band gap over a
+range of a few eV. These results suggest the possibility of creating and tuning
+the band gap in graphene by varying the oxidation level and the relative amount
+of epoxide and hydroxyl functional groups on the surface.",0908.3172v1
+2009-10-12,Chemical-etch-assisted growth of epitaxial zinc oxide,"We use real-time spectroscopic polarimetric observations of growth and a
+chemical model derived therefrom, to develop a method of growing dense,
+two-dimensional zinc oxide epitaxially on sapphire by metalorganic chemical
+vapor deposition. Particulate zinc oxide formed in the gas phase is used to
+advantage as the deposition source. Our real-time data provide unequivocal
+evidence that: a seed layer is required; unwanted fractions of ZnO are
+deposited; but these fractions can be removed by cycling between brief periods
+of net deposition and etching. The transition between deposition and etching
+occurs with zinc precursor concentrations that only differ by 13%. These
+processes are understood by considering the chemistry involved.",0910.2199v1
+2010-02-25,"Trends in Metal Oxide Stability for Nanorods, Nanotubes, and Surfaces","The formation energies of nanostructures play an important role in
+determining their properties, including the catalytic activity. For the case of
+15 different rutile and 8 different perovskite metal oxides, we find that the
+density functional theory (DFT) calculated formation energies of (2,2)
+nanorods, (3,3) nanotubes, and the (110) and (100) surfaces may be described
+semi-quantitatively by the fraction of metal--oxygen bonds broken and the
+bonding band centers in the bulk metal oxide.",1002.4834v1
+2010-06-11,"First Homologous Series of Iron Pnictide Oxide Superconductors (Fe2As2)(Can+1(Sc,Ti)nOy) [n = 3,4,5] with Extremely Thick Blocking Layers","We have discovered first homologous series of iron pnictide oxide
+superconductors (Fe2As2)(Can+1(Sc,Ti)nOy) [n = 3,4,5]. These compounds have
+extremely thick blocking layers up to quintuple perovskite oxide layers
+sandwiched by the Fe2As2 layers. These samples exhibited bulk superconductivity
+with relatively high Tc up to 42 K. The relationship between Tc and the
+iron-plane interlayer distance suggested that superconductivity due to the mono
+Fe2As2 layer is substantially 40 K-class.",1006.2355v2
+2010-07-02,$sp^{2}$/$sp^{3}$ carbon ratio in graphite oxide with different preparation times,"Graphite oxide is an amorphous insulator. Although several models have been
+suggested, its structure remains controversial. To elucidate this issue, 5
+samples were prepared by the Brodie process and the Staudenmaier process. The
+electronic structure of graphite oxide was examined with x-ray absorption near
+edge structure and the ratio of $sp^{2}$ to $sp^{3}$ bonded carbon atoms was
+investigated with x-ray photoemission spectroscopy as a function of sample
+preparation times. It was found that this ratio approaches 0.3 exponentially
+with a characteristic time of 1.5 weeks. We believe this long characteristic
+time is the reason the structure has remained unclear.",1007.0287v2
+2010-10-01,Thermally induced 0-pi phase transition in Josephson junctions through a ferromagnetic oxide film,"We investigate the Josephson transport through a ferromagnetic oxide film,
+e.g., La$_2$BaCuO$_5$, theoretically. Using the recursive Green's function
+technique, we found the formation of a pi-junction in such systems. Moreover
+the 0-pi phase transition is induced by increasing the temperature. Such
+ferromagnetic-oxide based Josephson junctions may become an element in the
+architecture of future quantum computers.",1010.0042v1
+2010-10-26,Transparent and conductive graphene oxide-polyethylenglycol diacrylate coatings obtained by photopolymerization,"Water dispersed graphene oxide sheets were used to prepare
+graphene-polyethylenglycol diacrylate resin composites by photopolymerization.
+It was found that graphene sheets undergo excellent morphological distribution
+within the resin system, giving rise to transparent composites with unaltered
+thermal properties with respect to the neat resin, that are electrically
+conductive at loading ratios as low as 0.02 %wt of graphene oxide . The
+proposed strategy based on photopolymerization provides an easy, energy-saving
+and environmental friendly technique that can find a wide application in
+coating technology, mainly for electromagnetic shielding and antistatic
+coatings.",1010.5409v1
+2010-11-16,Field-induced water electrolysis switches an oxide semiconductor from an insulator to a metal,"Here we demonstrate that water-infiltrated nanoporous glass electrically
+switches an oxide semiconductor from an insulator to metal. We fabricated the
+field effect transistor structure on an oxide semiconductor, SrTiO3, using
+100%-water-infiltrated nanoporous glass - amorphous 12CaO*7Al2O3 - as the gate
+insulator. For positive gate voltage, electron accumulation, water electrolysis
+and electrochemical reduction occur successively on the SrTiO3 surface at room
+temperature, leading to the formation of a thin (~3 nm) metal layer with an
+extremely high electron concentration of 10^15-10^16 cm^-2, which exhibits
+exotic thermoelectric behaviour.",1011.3681v1
+2010-12-22,Thermoelectric effect of multiferroic oxide interfaces,"We investigate the thermoelectric properties of electrons at the interface of
+oxide heterostructure and in the presence of a multiferroic oxide with spiral
+spin order. We find there is no (spin) Hall current generated by the
+temperature gradient. A Seebeck effect is however present. Due to the
+magnetoelectric coupling, the charge and thermal conductivities are
+electrically controllable via the spin spiral helicity. Moreover, the
+thermopower exhibits a sign change when tuning electro-statically the carrier
+density.",1012.4865v1
+2011-08-24,"Wettability and ""petal effect"" of GaAs native oxides","We discuss unreported transitions of oxidized GaAs surfaces between
+(super)hydrophilic and hydrophobic states when stored in ambient conditions.
+Contact angles higher than 90deg and high adhesive force were observed for
+several air-aged epitaxial samples grown under different conditions as well as
+on epi-ready wafers. Regardless of the morphologies of the surface,
+superhydrophilicity of oxygen-plasma treated samples was observed, an effect
+disappearing with storage time. Reproducible hydrophobicity was likewise
+observed, as expected, after standard HCl surface etching. The relation between
+surface oxides and hydrophobic/hydrophilic behavior is discussed.",1108.4789v1
+2012-07-03,Doping of Si nanoparticles: the effect of oxidation,"The preferred location of boron and phosphorus in oxidized free-standing Si
+nanoparticles was investigated using a first-principles density functional
+approach. The calculated formation energies indicate that P should segregate to
+the silicon core, whereas B is equally stable in the Si and SiO_2 regions. Our
+models thus suggest that, in contrast with nanocrystals with H-terminated
+surfaces, the efficiency of phosphorus incorporation in oxidized Si
+nanoparticles can be improved by thermal annealing.",1207.0770v2
+2012-11-21,Atomic scale characterization of the nucleation and growth of SnO2 particles in oxidized CuSn alloys,"The internal oxidation of Sn was investigated to understand the oxidation
+kinetics of monophase CuSn alloys. SnO2 particles were characterized by
+analytical transmission electron microscopy. The orientation relationship
+between SnO2 and Cu was determined with a special emphasis on the atomic scale
+structure of Cu/SnO2 interfaces (misfit dislocations and chemical structure).
+Habit planes with a pure oxygen plane terminating the SnO2 phase are greatly
+favored and large misfits promote the growth of plate shaped precipitates.",1211.5038v1
+2012-11-22,Physical properties and band structure of reactive molecular beam epitaxy grown oxygen engineered HfO$_{2\pm x}$,"We have conducted a detailed thin film growth structure of oxygen engineered
+monoclinic HfO$_{2\pm x}$ grown by reactive molecular beam epitaxy (MBE). The
+oxidation conditions induce a switching between ($\bar{1}11$) and (002) texture
+of hafnium oxide. The band gap of oxygen deficient hafnia decreases with
+increasing amount of oxygen vacancies by more than 1 eV. For high oxygen
+vacancy concentrations, defect bands form inside the band gap that induce
+optical transitions and $p$-type conductivity. The resistivity changes by
+several orders of magnitude as a function of oxidation conditions. Oxygen
+vacancies do not give rise to ferromagnetic behavior.",1211.5215v1
+2013-02-13,Theory of ferromagnetism in vanadium-oxide based perovskites,"The conditions under which ferromagnetism may occur in transition metal
+oxides with partially filled $t_{2g}$ shells such as vanadium-based perovskites
+are studied using a combination of density functional and single-site dynamical
+mean field methods. For reasonable values of the correlation strength,
+rotations of the VO$_6$ octahedra play an important role in enabling
+ferromagnetism, with ferromagnetism typically occurring for rotations larger
+than a nonzero critical value. Ferromagnetism is suppressed near the Mott
+insulating phase but the phase boundary is otherwise only weakly dependent on
+carrier concentration. Design rules are suggested for new oxide systems
+exhibiting ferromagnetism.",1302.3062v2
+2013-12-14,Formation and anisotropic magnetoresistance of Co/Pt nano-contacts through aluminum oxide barrier,"We report on the observation of anisotropic magnetoresistance (AMR) in
+vertical asymmetric nano-contacts (NCs) made through AlO$_x$ nano-oxide layer
+(NOL) formed by ion-assisted oxidation method in the film stack of
+Co/AlO$_x$-NOL/Pt. Analysis of NC formation was based on \emph{in situ}
+conductive atomic force microscopy and transmission electron microscopy.
+Depending on the purity of NCs from Al contamination, we observed up to 29% AMR
+ratio at room temperature.",1312.4061v1
+2014-01-29,Thermodynamic properties of yttrium cuprate,"The standard formation enthalpy and enthalpy from binary oxide of yttrium
+cuprate have been determined by solution calorimetry combining the solution
+enthalpies of Y2Cu2O5 and Y2O3 + 2CuO mixture in 6 M HCl at 323.15 K and
+literature data. The heat capacity of Y2Cu2O5 has been measured by adiabatic
+calorimetry from 8 up to 303 K. Smoothed values of heat capacities, entropies
+and enthalpies were calculated on the basis of experimental data. The
+thermodynamic functions (heat capacity, entropy and enthalpy) at 298.15 K have
+been calculated. On the basis of obtained data it has been obtained that
+above-mentioned complex oxide is thermodynamically unstable with respect to
+their decomposition into binary oxides at room temperatures.",1401.7422v1
+2014-11-23,Structural and electrochemical properties of MnO2-Carbon based supercapacitor electrodes,"We present results of an approach to incorporate redox-active manganese oxide
+into the 3-dimensional porous structure of carbon xerogels under self-limiting
+electroless conditions. By varying the structure of the carbon backbone, we
+found that deposition of manganese oxide preferably takes place on the external
+surface area of the carbon xerogels. From our detailed analysis we conclude
+that 3-dimensional carbon xerogels with particle and pore sizes ranging from 10
+to 20 nm and low manganese oxide precursor concentration combined with long
+deposition times are beneficial for fast operating pseudocapacitance electrodes
+with high capacitance and effective use of the redox active component.",1411.6278v1
+2015-06-04,In situ TEM observation of oxygen evolution reaction in GDC-Pt half cell at elevated temperatures,"Gadolinium-doped ceria was studied in a half SOFCs at elevated temperatures.
+In situ electron holography could reveal ionic activity in a single GDC-Pt
+interface at the elevated temperatures that result in further oxidation of the
+GDC. In situ EELS measurements confirmed holography results and showed the
+existence of the gadolinium in a new oxidation state. Also, it was found that
+the doped cations are the active ions in the oxygen evolution reaction from the
+solid oxide electrolyte.",1506.02067v1
+2015-10-01,Krypton oxides under pressure,"Under high pressure, krypton, one of the most inert elements is predicted to
+become sufficiently reactive to form a new class of krypton compounds; krypton
+oxides. Using modern ab-initio evolutionary algorithms in combination with
+Density Functional Theory, we predict the existence of several
+thermodynamically stable Kr/O species at elevated pressures. In particular, our
+calculations indicate that at approx. 300 GPa the monoxide, KrO, should form
+spontaneously and remain thermo- and dynamically stable with respect to
+constituent elements and higher oxides. The monoxide is predicted to form
+non-molecular crystals with short Kr-O contacts, typical for genuine chemical
+bonds.",1510.00255v1
+2016-03-15,Infrared dielectric properties of low-stress silicon oxide,"Silicon oxide thin films play an important role in the realization of optical
+coatings and high-performance electrical circuits. Estimates of the dielectric
+function in the far- and mid-infrared regime are derived from the observed
+transmittance spectrum for a commonly employed low-stress silicon oxide
+formulation. The experimental, modeling, and numerical methods used to extract
+the dielectric function are presented.",1603.04815v1
+2017-02-06,On the oxidation state of titanium in titanium dioxide,"The oxidation state of titanium in titanium dioxide is commonly assumed to be
++4. This assumption is used ubiquitously to rationalize phenomena observed with
+TiO2. We present a comprehensive electronic structure investigation of Ti ions,
+TiO2 molecules and TiO2 bulk crystals, using different density functional
+theory and wave function-based approaches, which suggests a lower oxidation
+state (+3). Specifically, there is evidence of a significant remaining
+contribution from valence s and d electrons of Ti, including the presence of a
+nuclear cusp around the Ti core. The charge corresponding to valence s and d
+states of Ti amounts to 1 e. The commonly assumed picture may therefore have to
+be revised.",1702.01555v1
+2017-02-18,Delta-doped Beta- Gallium Oxide Field Effect Transistor,"We report silicon delta doping in Gallium Oxide (\b{eta}-Ga2O3) grown by
+plasma assisted molecular beam epitaxy using a shutter pulsing technique. We
+describe growth procedures that can be used to realize high Si incorporation in
+an oxidizing oxygen plasma environment. Delta doping was used to realize thin
+(12 nm) low-resistance layers with sheet resistance of 320 Ohm/square (mobility
+of 83 cm^2/Vs, integrated sheet charge of 2.4x10^14 cm^-2). A single
+delta-doped sheet of carriers was employed as a channel to realize a field
+effect transistor with current ID,MAX =292 mA/mm and transconductance gM = 27
+mS/mm.",1702.06584v1
+2017-03-01,Infrared properties of micromachined vanadium oxide thin films,"This paper discusses questions of synthesizing and pressing vanadium oxides
+to create film-forming materials that can be used in producing optical
+coatings. Based on the film-forming materials thus created, technological
+processes have been developed for fabricating coatings from vanadium dioxide by
+two methods of producing thin films: vacuum evaporation and magnetron
+sputtering. Questions of using films made from vanadium oxide in optical
+instrumentation are considered.",1703.00127v1
+2018-02-23,Independence of surface morphology and reconstruction during the thermal preparation of perovskite oxide surfaces,"Using a CO$_2$ laser to directly heat the crystals from the back side,
+SrTiO$_3$ substrates may be thermally prepared in situ for epitaxy without the
+need for ex-situ etching and annealing. We find that the formation of large
+terraces with straight steps at 900-1100 {\deg}C is independent from the
+formation of the ideal surface reconstruction for epitaxy, which requires
+temperatures in excess of 1200 {\deg}C to complete. The process may be
+universal, at least for perovskite oxide surfaces, as it also works, at
+different temperatures, for LaAlO$_3$ and NdGaO$_3$, two other widely used
+oxide substrate materials.",1802.08423v1
+2018-03-30,Nanostructured Ceramic Oxides with a Slow Crack Growth Resistance Close to Covalent Materials,"Oxide ceramics are sensitive to slow crack growth because adsorption of water
+can take place at the crack tip, leading to a strong decrease of the surface
+energy in humid (or air) conditions. This is a major drawback concerning
+demanding, long-term applications such as orthopaedic implants. Here we show
+that a specific nanostructuration of ceramic oxides can lead to a crack
+resistance never reached before, similar to that of covalent ceramics.",1804.01393v1
+2020-07-04,Data-Mining Element Charges in Inorganic Materials,"Oxidation states are well-established in chemical science teaching and
+research. We data-mine more than 168,000 crystallographic reports to find an
+optimal allocation of oxidation states to each element. In doing so we uncover
+discrepancies between text-book chemistry and reported charge states observed
+in materials. We go on to show how the oxidation states we recommend can
+significantly facilitate materials discovery and heuristic design of novel
+inorganic compounds.",2007.02085v1
+2016-11-28,Dynamical mean field theory for oxide heterostructures,"Transition metal oxide heterostructures often, but by far not always, exhibit
+strong electronic correlations. State-of-the-art calculations account for these
+by dynamical mean field theory (DMFT). We discuss the physical situations in
+which DMFT is needed, not needed, and where it is actually not sufficient. By
+means of an example, SrVO$_3$/SrTiO$_3$, we discuss step-by-step and
+figure-by-figure a density functional theory(DFT)+DMFT calculation. The second
+part reviews DFT+DMFT calculations for oxide heterostructure focusing on
+titanates, nickelates, vanadates, and ruthenates.",1611.09044v1
+2017-04-04,Continuum model for hydrogen pickup in Zirconium alloys of LWR fuel cladding,"A continuum model for calculating the time-dependent hydrogen pickup
+fractions in various Zirconium alloys under steam and pressured water oxidation
+has been developed in this study. Using only one fitting parameter, the
+effective hydrogen gas partial pressure at the oxide surface, a qualitative
+agreement is obtained between the predicted and previously measured hydrogen
+pickup fractions. The calculation results therefore demonstrate that H
+diffusion through the dense oxide layer plays an important role in the hydrogen
+pickup process. The limitations and possible improvement of the model are also
+discussed.",1704.01201v1
+2017-04-04,Multibit memory operation of metal-oxide bi-layer memristors,"In this work, we evaluate a multitude of metal-oxide bi-layers and
+demonstrate the benefits from increased memory stability via multibit memory
+operation. We introduce a programming methodology that allows for operating
+metal-oxide memristive devices as multibit memory elements with highly packed
+yet clearly discernible memory states. We finally demonstrate a 5.5-bit memory
+cell (47 resistive states) with excellent retention and power consumption
+performance. This paves the way for neuromorphic and non-volatile memory
+applications.",1704.03313v1
+2008-07-18,AFM local oxidation nanolithography of graphene,"We demonstrate the local oxidation nanopatterning of graphene films by an
+atomic force microscope. The technique provides a method to form insulating
+trenches in graphene flakes and to fabricate nanodevices with sub-nm precision.
+We demonstrate fabrication of a 25-nm-wide nanoribbon and sub-micron size
+nanoring from a graphene flake. We also found that we can write either trenches
+or bumps on the graphene surface depending on the lithography conditions. We
+attribute the bumps to partial oxidation of the surface and incorporation of
+oxygen into the graphene lattice.",0807.2886v2
+2009-12-01,How Graphene Is Cut upon Oxidation?,"Our first principles calculations reveal that oxidative cut of graphene is
+realized by forming epoxy and then carbonyl pairs. Direct forming carbonyl pair
+to tear graphene up from an edge position is not favorable in energy. This
+atomic picture is valuable for developing effective graphene manipulation
+means. The proposed epoxy pairs may be related to some long puzzling
+experimental observations on graphene oxide.",0912.0083v1
+2009-12-04,Nanophotonic devices on thin buried oxide Silicon-On-Insulator substrates,"We demonstrate a silicon photonic platform using thin buried oxide
+silicon-on-insulator (SOI) substrates using localized substrate removal. We
+show high confinement silicon strip waveguides, micro-ring resonators and
+nanotapers using this technology. Propagation losses for the waveguides using
+the cutback method are 3.88 dB/cm for the quasi-TE mode and 5.06 dB/cm for the
+quasi-TM mode. Ring resonators with a loaded quality factor (Q) of 46,500 for
+the quasi-TM mode and intrinsic Q of 148,000 for the quasi-TE mode have been
+obtained. This process will enable the integration of photonic structures with
+thin buried oxide SOI based electronics.",0912.0775v1
+2011-11-08,Unusual ferromagnetism in nanoparticles of doped oxides and manganites,"The observation of unusually large ferromagnetism in the nanoparticles of
+doped oxides and enhanced ferromagnetic tendencies in manganite nanoparticles
+have been in focus recently. For the transition metal-doped oxide nanoparticles
+a phenomenological `charge transfer ferromagnetism' model is recently proposed
+by Coey et al. From a microscopic calculation with charge transfer between the
+defect band and mixed valent dopants, acting as reservoir, we show how the
+unusually high ferromagnetic response develops. The puzzle of nanosize-induced
+ferromagnetic tendencies in manganites is also addressed within the same
+framework where lattice imperfections and uncompensated charges at the surface
+of the nanoparticle are shown to reorganize the surface electronic structures
+with enhanced double exchange.",1111.1778v1
+2012-01-26,Resistive switching effects on the spatial distribution of phases in metal-complex oxide interfaces,"In order to determine the key parameters that control the resistive switching
+mechanism in metal-complex oxides interfaces, we have studied the electrical
+properties of metal / YBa2Cu3O7-d (YBCO) interfaces using metals with different
+oxidation energy and work function (Au, Pt, Ag) deposited by sputtering on the
+surface of a YBCO ceramic sample. By analyzing the IV characteristics of the
+contact interfaces and the temperature dependence of their resistance, we
+inferred that ion migration may generate or cancel conducting filaments, which
+modify the resistance near the interface, in accordance with the predictions of
+a recent model.",1201.5670v1
+2012-04-10,Analytical and numerical study of particles with binary adsorption,"Electro-oxidation of ethanol represents a key process in fuel-cells
+technology. We introduce a generalization of the random sequential adsorption
+model to study the long timescale and large length scale properties of the
+electro-oxidation process. We provide an analytical solution for one dimension
+and Monte Carlo results in two dimensions. We characterize the coverage and
+percolation properties of the jammed state and unveil the influence of quenched
+impurities in the selectivity of oxidation products.",1204.2093v1
+2012-04-25,Intrinsic Origin of Negative Fixed Charge in Wet Oxidation for Silicon Carbide,"We demonstrate on the basis of first-principles calculations that the
+formation of carbonate-like moiety in SiO$_2$ could be the intrinsic origin of
+negative fixed charge in SiC thermal oxidation. We find that two possible
+origins for the negative fixed charges are O-lone-pair state and a negatively
+charged CO$_3$ ion in SiO$_2$. Such CO$_3$ ion is able to be formed as a result
+of the existence of residual C atoms in SiO$_2$, which are expected to be
+emitted from the interface between SiC and SiO$_2$, and the incorporation of H
+atoms during wet oxidation.",1204.5556v1
+2015-12-08,Analysis of high quality superconducting resonators: consequences for TLS properties in amorphous oxides,"$1/f$ noise caused by microscopic Two-Level Systems (TLS) is known to be very
+detrimental to the performance of superconducting quantum devices but the
+nature of these TLS is still poorly understood. Recent experiments with
+superconducting resonators indicates that interaction between TLS in the oxide
+at the film-substrate interface is not negligible. Here we present data on the
+loss and $1/f$ frequency noise from two different Nb resonators with and
+without Pt capping and discuss what conclusions can be drawn regarding the
+properties of TLS in amorphous oxides. We also estimate the concentration and
+dipole moment of the TLS.",1512.02553v1
+2016-08-18,Geometrical lattice engineering of complex oxide heterostructures: a designer approach to emergent quantum states,"Epitaxial heterostructures composed of complex oxides have fascinated
+researchers for over a decade as they offer multiple degrees of freedom to
+unveil emergent many-body phenomena often unattainable in bulk. Recently, apart
+from stabilizing such artificial structures along the conventional
+[001]-direction, tuning the growth direction along unconventional
+crystallographic axes has been highlighted as a promising route to realize
+novel quantum many-body phases. Here we illustrate this rapidly developing
+field of geometrical lattice engineering with the emphasis on a few
+prototypical examples of the recent experimental efforts to design complex
+oxide heterostructures along the (111) orientation for quantum phase discovery
+and potential applications.",1608.05283v1
+2017-06-08,Ab initio studies of carbon dioxide affinity to carbon compounds and minerals,"We have performed quantum chemical computational studies to determine carbon
+dioxide affinity to carbon compounds and minerals, which could be present in
+shales. These studies shed light on the microscopic mechanisms of the possible
+carbon oxide sequestration processes. Our studies reveal that the carbon oxide
+can be adsorbed to various forms of carbon structures and also minerals such as
+periclase or illite. We find out that the strongest affinity of carbon oxide
+towards carbon structures occurs when the carbon structures exhibit $sp^3$
+bonds.",1706.02572v1
+2017-10-10,Growth of Antiperovskite Oxide Ca3SnO Films by Pulsed Laser Deposition,"We report the epitaxial growth of Ca3SnO antiperovskite oxide films on
+(001)-oriented cubic yttria-stabilized zirconia (YSZ) substrates by using a
+conventional pulsed laser deposition (PLD) technique. In this work, a sintered
+Ca3SnO pellet is used as the ablation target. X-ray diffraction measurements
+demonstrate the (001) growth of Ca3SnO films with the antiperovskite structure
+and a cube-on-cube orientation relationship to the YSZ substrate. The
+successful synthesis of the antiperovskite phase is further confirmed by x-ray
+photoemission spectroscopy. These results strongly suggest that
+antiperovskite-oxide films can be directly grown on substrates from the target
+material using a PLD technique.",1710.03406v1
+2020-04-28,High mobility conducting channel at semi-insulating GaAs -- metal oxide interfaces,"Absence of an efficient technology of GaAs passivation limits the use of
+III-V semiconductors in modern electronics. The effect reported here can
+possibly lead to a solution of this long standing problem. We found that an
+electrically conducting interfacial channel is formed when insulating metal
+oxide dielectrics are deposited on untreated semi-insulating GaAs wafers by
+reactive RF sputtering in argon/oxygen plasma. The conducting channel is n-type
+with the surface charge density of 10^7 to 10^10 cm^-2 and Hall mobility as
+high as 6000 cm^2/Vsec, depending on the RF plasma excitation power and oxygen
+content during the deposition. The conducting channel is formed by depositing
+any of the tested metal oxide dielectrics: MgO, SiO2, Al2O3 and HfO2.",2004.13543v1
+2012-05-02,Nanoscale Plasmonic and Optical Modulators Based on Transparent Conducting Oxides,"Recent experiments showed that unity-order index change in a transparent
+conducting oxide (TCO) can be achieved in a metal-oxide-semiconductor (MOS)
+structure by accumulation charge. However, the ultrathin (~5nm) accumulation
+layer and inherent absorption of TCOs impede the practical applications of this
+effect. Herein, we propose and explore a novel waveguide, namely ""TCO-slot
+waveguide"", which combines both the tunable property of a TCO and field
+enhancement of a slot waveguide. In particular, light absorption can be sharply
+enhanced when the slot dielectric constant is tuned close to zero. Based on
+TCO-slot waveguides, efficient electro-absorption modulation can be achieved
+within 200 nm with small insertion loss.",1205.0502v1
+2017-05-02,Carbon Ejection from a SiO2/SiC(0001) Interface by Annealing in High-Purity Ar,"We found that carbon-associated byproducts formed at the dry-oxidized
+SiO2/SiC(0001) interface could be decomposed and be taken out to the SiO2 side
+by high-purity Ar annealing. We evaluated the concentration of the ejected
+carbon atoms in the SiO2 by secondary ion mass spectrometry, and discovered
+that it clearly depends on the condition of oxide formation (dry-oxidation,
+nitridation treatment, and phosphorus treatment). This work provides an
+indirect but unambiguous evidence for the carbon-byproducts existing at the
+SiO2/SiC interfaces, and also indicates that the phosphorus treatment removes
+the carbon-byproducts, leading to significant reduction of interface defects.",1705.00814v1
+2017-11-20,"Structural, Optical and Electronic properties of Magnetron Sputtered Si and Ge thin films","We report the results of GIXRR, UV-VIS NIR and XPS measurements on Si and Ge
+thin films of various thicknesses. While GIXRR measurements show no presence of
+oxide on the top of these films, XPS measurements show small amount of oxides.
+Also, a sharp increase in surface roughness is seen with thickness in agreement
+with the columnar growth of films. In contrast, in case of Si films, oxide is
+present even inside the layers but in a very small amount and is not detected
+in GIXRR/absorption measurements.",1711.07174v1
+2019-01-08,Structure and Synthesis of graphene oxide,"Graphene oxide (GO) is regarded as one typical two-dimension structured
+oxygenated planar molecular material. Researchers across multiple disciplines
+have paid enormous attention to it due to unique physiochemical properties.
+However, models used to describe the structure of GO are still in argument and
+ongoing to update. Currently, synthesis methods for massive production are
+seemingly abundant but in fact, dominated by few thought systems. We herein aim
+to give a mini but critical review over the synthesis of graphene oxide as well
+as its structure, involving relative peer work.",1901.02274v2
+2019-08-06,Surface terraces in pure tungsten formed by high-temperature oxidation,"We observe large-scale surface terraces in tungsten oxidised at high
+temperature and in high vacuum. Their formation is highly dependent on crystal
+orientation, with only {111} grains showing prominent terraces. Terrace facets
+are aligned with {100} crystallographic planes, leading to an increase in total
+surface energy, making a diffusion-driven formation mechanism unlikely. Instead
+we hypothesize that preferential oxidation of {100} crystal planes controls
+terrace formation. Grain height profiles after oxidation and the morphology of
+samples heat treated with limited oxygen supply are consistent with this
+hypothesis. Our observations have important implications for the use of
+tungsten in extreme environments.",1908.02036v1
+2021-03-20,Influence of nonlinear- and saturable-absorption on laser lift-off threshold of oxide/metal structure,"In this work, a new model of effective lift-off threshold of oxide/metal
+target is presented. The influence of nonlinear processes in the oxide layer on
+its removal from the metallic samples using picosecond laser was investigated.
+Nonlinear and saturable absorption in the layer was incorporated into modeling
+for prediction of effective laser lift-off threshold fluence change with
+varying peak intensities in z-scan type experiment for the first time. The new
+model coincides well with the experimental results.",2103.11140v2
+2022-07-25,Experimental evaluation of a silicone oil as an oxidation inhibitor for magnesium alloy under contact sliding at elevated temperatures,"This paper experimentally investigated the effects of silicone oil on the
+tribological behaviour of AZ31B/86CrMoV7 contact pair under a pin-on-disk
+configuration. A commercial silicone oil was used as an oxidation inhibiter for
+the AZ31B at elevated temperatures to 300 oC. The wear mechanism of the contact
+pair was explored by SEM morphologies of worn surfaces. The analysis revealed
+that silicone oil can effectively minimize surface oxidation. Compared with dry
+sliding, silicone oil can considerably lower down the friction coefficient and
+specific wear rate. Under lubrication, the abrasive wear at a lower temperature
+can transit to the combined wear of abrasion, fatigue and adhesion when the
+temperature rises.",2207.11908v1
+2022-12-21,Impact of different metal electrodes on the ferroelectric properties of hafnium-zirconium oxide in M1/FE/M2 structures during the electric field cycling,"The interest in the ferroelectric non-volatile memory as a candidate for low
+power consumption electronic memories was raised after the discovery of
+ferroelectricity in hafnium oxide. Doping by different elements of hafnia films
+allows improving their ferroelectric properties. In this work, the transport
+experiments are combined with the simulations to study the evolution of
+ferroelectric properties and the mean distance between oxygen vacancies during
+the endurance of hafnium-zirconium oxide in metal-ferroelectric-metal
+structures to study the impact of different metal electrodes.",2212.10858v1
+2023-03-23,Antiferromagnetic insulatronics: spintronics in insulating 3d metal oxides with antiferromagnetic coupling,"Antiferromagnetic transition metal oxides are an established and widely
+studied materials system in the context of spin-based electronics, commonly
+used as passive elements in exchange bias-based memory devices. Currently,
+major interest has resurged due to the recent observation of long-distance spin
+transport, current-induced switching, and THz emission. As a result, insulating
+transition metal oxides are now considered to be attractive candidates for
+active elements in novel spintronic devices. Here, we discuss some of the most
+promising materials systems and highlight recent advances in reading and
+writing antiferromagnetic ordering. This article aims to provide an overview of
+the current research and potential future directions in the field of
+antiferromagnetic insulatronics.",2303.13369v1
+2003-02-06,Sub-surface Oxygen and Surface Oxide Formation at Ag(111): A Density-functional Theory Investigation,"To help provide insight into the remarkable catalytic behavior of the
+oxygen/silver system for heterogeneous oxidation reactions, purely sub-surface
+oxygen, and structures involving both on-surface and sub-surface oxygen, as
+well as oxide-like structures at the Ag(111) surface have been studied for a
+wide range of coverages and adsorption sites using density-functional theory.
+Adsorption on the surface in fcc sites is energetically favorable for low
+coverages, while for higher coverage a thin surface-oxide structure is
+energetically favorable. This structure has been proposed to correspond to the
+experimentally observed (4x4) phase. With increasing O concentrations, thicker
+oxide-like structures resembling compressed Ag2O(111) surfaces are
+energetically favored. Due to the relatively low thermal stability of these
+structures, and the very low sticking probability of O2 at Ag(111), their
+formation and observation may require the use of atomic oxygen (or ozone, O3)
+and low temperatures. We also investigate diffusion of O into the sub-surface
+region at low coverage (0.11 ML), and the effect of surface Ag vacancies in the
+adsorption of atomic oxygen and ozone-like species. The present studies,
+together with our earlier investigations of on-surface and
+surface-substitutional adsorption, provide a comprehensive picture of the
+behavior and chemical nature of the interaction of oxygen and Ag(111), as well
+as of the initial stages of oxide formation.",0302122v1
+2007-02-15,Tip artifact in atomic force microscopy observations of InAs quantum dots grown in Stranski-Krastanow mode,"The tip artifact in atomic force microscopy (AFM) observations of InAs
+islands was evaluated quantitatively. The islands were grown in the
+Stranski-Krastanow mode of molecular beam epitaxy. The width and height of the
+islands were determined using transmission electron microscopy (TEM) and AFM.
+The average $[\bar{1}10]$ in-plane width and height determined using TEM
+excluding native oxide were 22 and 7 nm, respectively; those determined using
+AFM including the oxide were 35 and 8 nm, respectively. The difference in width
+was due to the oxide and the tip artifact. The sizes including the oxide were
+deduced from TEM observations to be a width of 27 nm and a height of 6 nm with
+correction for the thickness of the oxide. The residual difference of 8 nm
+between the width determined using AFM and that determined using TEM including
+the oxide was ascribed to the tip artifact. The results enable us to determine
+the actual size of the islands from their AFM images.",0702354v1
+2007-08-03,Time course of oxidative damage in different brain regions following transient cerebral ischemia in gerbils,"The time course of oxidative damage in different brain regions was
+investigated in the gerbil model of transient cerebral ischemia. Animals were
+subjected to both common carotid arteries occlusion for 5 min. After the end of
+ischemia and at different reperfusion times (2, 6, 12, 24, 48, 72, 96 h and 7
+days), markers of lipid peroxidation, reduced and oxidized glutathione levels,
+glutathione peroxidase, glutathione reductase, manganese-dependent superoxide
+dismutase (MnSOD) and copper/zinc containing SOD (Cu/ZnSOD) activities were
+measured in hippocampus, cortex and striatum. Oxidative damage in hippocampus
+was maximal at late stages after ischemia (48-96 h) coincident with a
+significant impairment in glutathione homeostasis. MnSOD increased in
+hippocampus at 24, 48 and 72 h after ischemia, coincident with the marked
+reduction in the activity of glutathione-related enzymes. The late disturbance
+in oxidant-antioxidant balance corresponds with the time course of delayed
+neuronal loss in the hippocampal CA1 sector. Cerebral cortex showed early
+changes in oxidative damage with no significant impairment in antioxidant
+capacity. Striatal lipid peroxidation significantly increased as early as 2 h
+after ischemia and persisted until 48 h with respect to the sham-operated
+group. These results contribute significant information on the timing and
+factors that influence free radical formation following ischemic brain injury,
+an essential step in determining effective antioxidant intervention.",0708.0572v1
+2009-01-23,The DNA Single-Strand Break Repair Machinery Facilitates CAF-1-Mediated Histone Deposition at Oxidative DNA Strand Breaks,"Oxidative DNA single strand breaks arise continuously in cells and defects in
+their repair have been implicated in neurological disease. While much progress
+has been made in understanding how chromosomal single strand breaks are
+repaired little is known about the changes chromatin structure that accompany
+this process. Here, we show that nascent recombinant histone H3.1 protein
+accumulates and is deposited into chromatin at sites of DNA strand breakage in
+quiescent human cells following oxidative stress, and that core components of
+the single-strand break repair machinery are required for this process. We show
+that the SSBR sensor and scaffold proteins poly (ADP-ribose) polymerase and
+XRCC1 facilitate accumulation of chromatin assembly factor-1 (CAF-1) at sites
+of oxidative DNA strand breakage, which in turn mediates the deposition of
+Histone H3.1. We also demonstrate that depletion of CAF-1 slows global rates of
+DNA strand break repair in quiescent cells following oxidative stress,
+demonstrating that single-strand break repair and histone deposition are
+tightly coordinated processes. These data describe a novel role for the DNA
+singlestrand break repair machinery and implicate histone turnover as a core
+component of the cellular response of quiescent cells to oxidative damage.",0901.3719v4
+2010-01-25,Novel Multifunctional Materials Based on Oxide Thin Films and Artificial Heteroepitaxial Multilayers,"Transition metal oxides show fascinating physical properties such as high
+temperature superconductivity, ferro- and antiferromagnetism, ferroelectricity
+or even multiferroicity. The enormous progress in oxide thin film technology
+allows us to integrate these materials with semiconducting, normal conducting,
+dielectric or non-linear optical oxides in complex oxide heterostructures,
+providing the basis for novel multi-functional materials and various device
+applications. Here, we report on the combination of ferromagnetic,
+semiconducting, metallic, and dielectric materials properties in thin films and
+artificial heterostructures using laser molecular beam epitaxy. We discuss the
+fabrication and characterization of oxide-based ferromagnetic tunnel junctions,
+transition metal-doped semiconductors, intrinsic multiferroics, and artificial
+ferroelectric/ferromagetic heterostructures - the latter allow for the detailed
+study of strain effects, forming the basis of spin-mechanics. For
+characterization we use X-ray diffraction, SQUID magnetometry, magnetotransport
+measurements, and advanced methods of transmission electron microscopy with the
+goal to correlate macroscopic physical properties with the microstructure of
+the thin films and heterostructures.",1001.4447v2
+2012-02-03,Temperature-dependent electron microscopy study of Au thin films on Si (100) with and without native oxide layer as barrier at the interface,"Real time electron microscopy observation on morphological changes in gold
+nano structures deposited on Si (100) surfaces as a function of annealing
+temperatures has been reported. Two types of interfaces with the substrate
+silicon were used prior to gold thin film deposition: (i) without native oxide
+and on ultra-clean reconstructed Si surfaces and (ii) with native oxide covered
+Si surfaces. For a \approx 2.0 nm thick Au films deposited on reconstructed
+Si(100) surfaces using molecular beam epitaxy method under ultra high vacuum
+conditions, aligned four-fold symmetric nanogold silicide structures formed at
+relatively lower temperatures (compared with the one with native oxide at the
+interface). For this system, 82% of the nanostructures were found to be nano
+rectangles like structures with an average length \approx 27 nm and aspect
+ratio of 1.13 at \approx 700{\deg}C. For \approx 5.0 nm thick Au films
+deposited on Si (100) surface with native oxide at the interface, formation of
+rectangular structures were observed at higher temperatures (\approx 850{\deg}
+C). At these high temperatures, desorption of the gold silicide followed the
+symmetry of the substrate. Native oxide at the interface was found to act like
+a barrier for the inter-diffusion phenomena. Structural characterization was
+carried out using advanced electron microscopy methods.",1202.0647v1
+2012-09-29,Passivity of Metals in the Point Defect Model: Effect of Chloride [Part-III],"In this paper we study the effect of addition of chloride on the stability of
+the compact oxide layer pre-existing on a metal surface at a given impressed
+potential and . The variant of the point defect model (PDM)advanced by us
+recently is used to construct a theory for the chloride-induced build-up of
+metal vacancies at the metal-film interface and the chloride-induced
+dissolution of the compact oxide layer. Under the quasi-steady-state
+approximation the relevant moving boundary value problem is solved exactly and
+analytical expressions are found for the incubation time, oxide dissolution
+time, and critical pitting potential, the time evolution of the passive current
+density and the metal vacancy concentration and the dependence of these
+quantities on the chloride ion concentration. Some diagnostics are also
+provided. The replacement of a reaction of the original PDM by another reaction
+in the variant is shown to have important consequences for the chloride-ion
+effect. While the original PDM invoked the Schottky-pair reaction to couple the
+chloride ion to the cation flux and to the metal vacancy generation, the
+present model couples the chloride ion directly to the metal vacancy
+annihilation without invoking the Schottky-pair reaction. The anion
+flux-pinning by chloride is shown to be sufficient to destabilize the oxide
+layer. An interesting conclusion of the present work is that thicker oxide
+layers are in general more susceptible to pitting due to the chloride ion and
+thinner oxide layers destabilize by simple dissolution in the presence of
+chloride.",1210.0099v1
+2013-11-04,Molecular responses of mouse macrophages to copper and copper oxide nanoparticles inferred from proteomic analyses,"The molecular responses of macrophages to copper-based nanoparticles have
+been investigated via a combination of proteomic and biochemical approaches,
+using the RAW264.7 cell line as a model. Both metallic copper and copper oxide
+nanoparticles have been tested, with copper ion and zirconium oxide
+nanoparticles used as controls. Proteomic analysis highlighted changes in
+proteins implicated in oxidative stress responses (superoxide dismutases and
+peroxiredoxins), glutathione biosynthesis, the actomyosin cytoskeleton, and
+mitochondrial proteins (especially oxidative phosphorylation complex subunits).
+Validation studies employing functional analyses showed that the increases in
+glutathione biosynthesis and in mitochondrial complexes observed in the
+proteomic screen were critical to cell survival upon stress with copper-based
+nanoparticles; pharmacological inhibition of these two pathways enhanced cell
+vulnerability to copper-based nanoparticles, but not to copper ions.
+Furthermore, functional analyses using primary macrophages derived from bone
+marrow showed a decrease in reduced glutathione levels, a decrease in the
+mitochondrial transmembrane potential, and inhibition of phagocytosis and of
+lipopolysaccharide-induced nitric oxide production. However, only a fraction of
+these effects could be obtained with copper ions. In conclusion, this study
+showed that macrophage functions are significantly altered by copper-based
+nanoparticles. Also highlighted are the cellular pathways modulated by cells
+for survival and the exemplified cross-toxicities that can occur between
+copper-based nanoparticles and pharmacological agents.",1311.0802v1
+2014-11-02,Re-visiting the O/Cu(111) system -- When metastable surface oxides could become an issue!,"Surface oxidation processes are crucial for the functionality of Cu-based
+catalytic systems used for methanol synthesis, partial oxidation of methanol or
+the water-gas shift reaction. We assess the stability and population of the
+""8""-structure, a $|\begin{smallmatrix} 3&2\\ -1&2 \end{smallmatrix}|$ oxide
+phase, on the Cu(111) surface. This structure has been observed in x-ray
+photoelectron spectroscopy and low-energy electron diffraction experiments as a
+Cu(111) surface reconstruction that can be induced by a hyperthermal oxygen
+molecular beam. Using density-functional theory calculations in combination
+with \textit{ab initio} atomistic thermodynamics and Boltzmann statistical
+mechanics, we find that the proposed oxide superstructure is indeed metastable
+and that the population of the ""8""-structure is competitive with the known ""29""
+and ""44"" oxide film structures on Cu(111). We show that the configuration of O
+and Cu atoms in the first and second layers of the ""8""-structure closely
+resembles the arrangement of atoms in the first two layers of Cu$_2$O(110),
+where the atoms in the ""8""-structure are more constricted. Cu$_2$O(110) has
+been suggested in the literature as the most active low index facet for
+reactions such as water splitting under light illumination. If the
+""8""-structure were to form during a catalytic process, it is therefore likely
+to be one of the reactive phases.",1411.0276v1
+2014-12-15,High-Mobility Bismuth-based Transparent P-Type Oxide from High-throughput Material Screening,"Transparent oxides are essential building blocks to many technologies,
+ranging from components in transparent electronics, transparent conductors, to
+absorbers and protection layers in photovoltaics and photoelectrochemical
+devices. However, thus far, it has been difficult to develop p-type oxides with
+wide band gap and high hole mobility; current state-of-art transparent p-type
+oxides have hole mobility in the range of < 10 cm$^2$/Vs, much lower than their
+n-type counterparts. Using high-throughput computational screening to guide the
+discovery of novel oxides with wide band gap and high hole mobility, we report
+the computational identification and the experimental verification of a
+bismuth-based double-perovskite oxide that meets these requirements. Our
+identified candidate, Ba$_2$BiTaO$_6$, has an optical band gap larger than 4 eV
+and a Hall hole mobility above 30 cm$^2$/Vs. We rationalize this finding with
+molecular orbital intuitions; Bi$^{3+}$ with filled s-orbitals strongly overlap
+with the oxygen p, increasing the extent of the metal-oxygen covalency and
+effectively reducing the valence effective mass, while Ta$^{5+}$ forms a
+conduction band with low electronegativity, leading to a high band gap beyond
+the visible range. Our concerted theory-experiment effort points to the growing
+utility of a data-driven materials discovery and the combination of both
+informatics and chemical intuitions as a way to discover future technological
+materials.",1412.4429v1
+2014-12-20,Surface Energetics of Alkaline-Earth Metal Oxides: Trends in Stability and Adsorption of Small Molecules,"We present a systematic theoretical investigation of the surface properties,
+stability and reactivity, of rock-salt type alkaline-earth metal oxides
+including MgO, CaO, SrO, and BaO. The accuracy of commonly used
+exchange-correlation density functionals (LDA, PBE, RPBE, PBEsol, BEEF-vdW and
+hybrid HSE) and random-phase approximation (RPA) is evaluated and compared to
+existing experimental values. Calculated surface energies of the four most
+stable surface facets under vacuum conditions: the (100) surface, the metal and
+oxygen terminated octopolar (111), and the (110) surfaces exhibit a monotonic
+increase in stability from MgO to BaO. On the MgO(100) surface, adsorption of
+CO, NO, CH4 is characterized by physisorption while H2O chemisorbs, which is in
+agreement with experimental findings. We further use the on-top metal
+adsorption of CO and NO molecules to map out the surface energetics of each
+alkaline-earth metal oxide surface. The considered functionals all
+qualitatively predict similar adsorption energy trends. The ordering between
+the adsorption energies on different surface facets can be attributed to
+differences in the local geometrical surface structure and the electronic
+structure of the metal constituent of the alkaline-earth metal oxide. The
+striking observation that CO adsorption strength is weaker than NO adsorption
+on the (100) terraces as the period of the alkaline-earth metal in the oxide
+increases, is analyzed in detail in terms of charge redistribution within the
+{\sigma} and {\pi} channels of adsorbates. Finally, we also present oxygen
+adsorption and oxygen vacancy formation energies in these oxide systems.",1412.6585v2
+2015-07-14,Thermal Oxidation of WSe2 Nano-sheets Adhered on SiO2/Si Substrates,"Due to the drastically different intralayer versus interlayer bonding
+strengths, the mechanical, thermal, and electrical properties of
+two-dimensional (2D) materials are highly anisotropic between the in-plane and
+out-of-plane directions. The structural anisotropy may also play a role in
+chemical reactions, such as oxidation, reduction, and etching. Here, the
+composition, structure, and electrical properties of mechanically exfoliated
+WSe2 nano- sheets on SiO2/Si substrates were studied as a function of the
+extent of thermal oxidation. A major component of the oxidation, as indicated
+from optical and Raman data, starts from the nano-sheet edges and propagates
+laterally towards the center. Partial oxidation also occurs in certain areas at
+the surface of the flakes, which are shown to be highly conductive by microwave
+impedance microscopy. Using secondary ion mass spectroscopy, we also observed
+extensive oxidation at the WSe2/SiO2 interface. The combination of multiple
+microcopy methods can thus provide vital information on the spatial evolution
+of chemical reactions on 2D materials and the nanoscale electrical properties
+of the reaction products.",1507.04048v1
+2015-10-08,Nearly-free electrons in a 5d delafossite oxide metal,"Understanding the role of electron correlations in strong spin-orbit
+transition-metal oxides is key to the realisation of numerous exotic phases
+including spin-orbit assisted Mott insulators, correlated topological solids,
+and prospective new high-temperature superconductors. To date, most attention
+has been focussed on the $5d$ iridium-based oxides. Here, we instead consider
+the Pt-based delafossite oxide PtCoO$_2$. Our transport measurements, performed
+on single-crystal samples etched to well-defined geometries using focussed
+ion-beam techniques, yield a room-temperature resistivity of only
+2.1~$\mu\Omega$cm, establishing PtCoO$_2$ as the most conductive oxide known.
+From angle-resolved photoemission and density-functional theory, we show that
+the underlying Fermi surface is a single cylinder of nearly hexagonal
+cross-section, with very weak dispersion along k$_z$. Despite being
+predominantly composed of $d$-orbital character, the conduction band is
+remarkably steep, with an average effective mass of only 1.14$m_e$. Moreover,
+the sharp spectral features observed in photoemission remain well-defined with
+little additional broadening for over 500~meV below E$_F$, pointing to
+suppressed electron-electron scattering. Together, our findings establish
+PtCoO$_2$ as a model nearly-free electron system in a $5d$ delafossite
+transition-metal oxide.",1510.02439v1
+2016-03-09,Quantization of Hall Resistance at the Metallic Interface between an Oxide Insulator and SrTiO$_{3}$,"The two-dimensional metal forming at the interface between an oxide insulator
+and SrTiO3 provides new opportunities for oxide electronics. However, the
+quantum Hall effect, one of the most fascinating effects of electrons confined
+in two dimensions, remains underexplored at these complex oxide
+heterointerfaces. Here, we report the experimental observation of quantized
+Hall resistance in a SrTiO3 heterointerface based on the modulation-doped
+amorphous-LaAlO$_{3}$/SrTiO$_{3}$ heterostructure, which exhibits both high
+electron mobility exceeding 10000 cm$^{2}$/Vs and low carrier density on the
+order of ~10$^{12}$ cm$^{-2}$. Along with unambiguous Shubnikov-de Haas
+oscillations, the spacing of the quantized Hall resistance suggests that the
+interface is comprised of a single quantum well with ten parallel conducting
+two-dimensional subbands. This provides new insight into the electronic
+structure of conducting oxide interfaces and represents an important step
+towards designing and understanding advanced oxide devices.",1603.02850v2
+2016-07-28,Two-Dimensional Boron Oxides with Dirac Loop and Strongly anisotropic Carrier Mobility,"Recently, two-dimensional boron sheets have attracted a lot of attentions
+owing to their structural polymorphs and outstanding properties. And, due to
+chemical complexity and electron deficiency of B atoms, the 2D boron sheets are
+easy affected by the environment. So, exploring novel 2D boron oxides gets
+highly needed. In this study, we theoretically explored 2D boron oxides
+structures and their basic properties. We found 2D boron oxides are metals or
+semimetals, when oxygen concentration is low. More interesting, the B6O1
+exhibits Dirac Loop near the Fermi level and the maximum Fermi velocity is
+estimated as high as 0.61*10E6 m/s, which much close to that in graphene. In
+addition, when the oxygen concentration is one forth, the most stable B4O1 get
+a semiconductor with a direct band gap of 1.24 eV and a strong anisotropic
+carrier mobility. Such huge differences of carrier mobility between two
+directions have not been reported in other 2D materials. Besides, when oxygen
+concentra-tion is higher than one forth, the 2D boron sheets will get unstable
+based our results. We also proposed a method how to synthesize these systems.
+Our work provide a basic knowledge of 2D boron oxides and may lead to novel 2D
+boron oxides discovered. The unique electronic properties of the B6O1 and B4O1
+render them promising 2D materials for applications in high-performance
+nanodevices.",1607.08290v1
+2017-03-08,Oxidation-Mediated Fingering in Liquid Metals,"We identify and characterize a new class of fingering instabilities in liquid
+metals; these instabilities are unexpected due to the large interfacial tension
+of metals. Electrochemical oxidation lowers the effective interfacial tension
+of a gallium-based liquid metal alloy to values approaching zero, thereby
+inducing drastic shape changes, including the formation of fractals. The
+measured fractal dimension ($D = 1.3 \pm 0.05$) places the instability in a
+different universality class than other fingering instabilities. By
+characterizing changes in morphology and dynamics as a function of droplet
+volume and applied electric potential, we identify the three main forces
+involved in this process: interfacial tension, gravity, and oxidative stress.
+Importantly, we find that electrochemical oxidation can generate compressive
+interfacial forces that oppose the tensile forces at a liquid interface. Thus,
+the surface oxide layer not only induces instabilities, but ultimately provides
+a physical barrier that halts the instabilities at larger positive potentials.
+Controlling the competition between surface tension and oxidative (compressive)
+stresses at the interface is important for the development of reconfigurable
+electronic, electromagnetic, and optical devices that take advantage of the
+metallic properties of liquid metals.",1703.03011v1
+2017-08-15,Effects of ultrasound waves intensity on the removal of Congo red color from the textile industry wastewater by Fe3O4@TiO2 core-shell nanospheres,"Environmental pollutants, such as colors from the textile industry, affect
+water quality indicators like color, smell, and taste. These substances in the
+water cause the obstruction of filters and membranes and thereby reduce the
+efficiency of advanced water treatment processes. In addition, they are harmful
+to human health because of reaction with disinfectants and production of
+by-products. Iron oxide nanoparticles are considered effective absorbents for
+the removal of pollutants from aqueous environments. In order to increase the
+stability and dispersion, nanospheres with iron oxide core and titanium dioxide
+coating were used in this research and their ability to absorb Congo red color
+was evaluated. Iron oxide-titanium oxide nanospheres were prepared based on the
+coprecipitation method and then their physical properties were determined using
+a tunneling electron microscope (TEM) and an X-ray diffraction device.
+Morphological investigation of the absorbent surface showed that iron
+oxide-titanium oxide nanospheres sized about 5 to 10 nm. X-ray dispersion
+survey also suggested the high purity of the sample. In addition, the
+absorption rate was measured in the presence of ultrasound waves and the
+results indicated that the capacity of the synthesized sample to absorb Congo
+red is greatly dependent on the intensity power of ultrasound waves, as the
+absorption rate reaches 100% at powers above 30 watts.",1708.04683v2
+2018-11-06,Effect of surface oxidation on electron spin coherence of single nitrogen-vacancy centers in nanodiamonds,"Fluorescent nanodiamonds (NDs) are crystal defect-based light-emitting
+nanoparticles that can be applied to quantum information science and quantum
+sensing. Of particular interest are nitrogen vacancy (NV) centers that allow
+optical access to their coherently controllable electron spin systems, leading
+to spin-photon quantum devices and nanoscale sensing of various physical
+parameters. However, the NV spin coherence time (T2) in NDs has been limited to
+one or two orders of magnitude shorter than those in bulk diamonds owing to the
+complicated surface effect that decoheres the NV spin systems. Here, we study
+the relation between the surface properties and T2 of single NV centers in NDs
+by systematically analyzing the effect of surface oxidation. We apply aerobic
+and acidic oxidation methods with various heating temperatures and processing
+times and find that aerobic oxidation most effectively oxidizes the surface and
+extends T2 by a factor of 1.6 to the original NDs. The ND-size dependence of T2
+clearly shows that the surface oxidation removes a constant decoherence
+contribution irrespective of the ND size and that a new surface derived
+decoherence source emerges when the ND size reduces below 50 nm. The present
+results provide quantitative information on the decoherence sources of NV spin
+systems of NDs and will enable a strategic surface modification for better spin
+manipulations of NV centers in the context of quantum information science and
+nanoscale quantum sensing.",1811.02235v2
+2018-11-12,Laser writable high-K dielectric for van der Waals nano-electronics,"Like silicon-based semiconductor devices, van der Waals heterostructures will
+require integration with high-K oxides. This is needed to achieve suitable
+voltage scaling, improved performance as well as allowing for added
+functionalities. Unfortunately, commonly used high-k oxide deposition methods
+are not directly compatible with 2D materials. Here we demonstrate a method to
+embed a multi-functional few nm thick high-k oxide within van der Waals devices
+without degrading the properties of the neighbouring 2D materials. This is
+achieved by in-situ laser oxidation of embedded few layer HfS2 crystals. The
+resultant oxide is found to be in the amorphous phase with a dielectric
+constant of k~15 and break-down electric fields in the range of 0.5-0.6 V/nm.
+This transformation allows for the creation of a variety of fundamental
+nano-electronic and opto-electronic devices including, flexible Schottky
+barrier field effect transistors, dual gated graphene transistors as well as
+vertical light emitting and detecting tunnelling transistors. Furthermore, upon
+dielectric break-down, electrically conductive filaments are formed. This
+filamentation process can be used to electrically contact encapsulated
+conductive materials. Careful control of the filamentation process also allows
+for reversible switching between two resistance states. This allows for the
+creation of resistive switching random access memories (ReRAMs). We believe
+that this method of embedding a high-k oxide within complex van der Waals
+heterostructures could play an important role in future flexible
+multi-functional van der Waals devices.",1811.04829v1
+2020-06-30,Growth kinetics and atomistic mechanisms of native oxidation of ZrS$_x$Se$_{2-x}$ and MoS$_2$ crystals,"A thorough understanding of native oxides is essential for designing
+semiconductor devices. Here we report a study of the rate and mechanisms of
+spontaneous oxidation of bulk single crystals of ZrS$_x$Se$_{2-x}$ alloys and
+MoS$_2$. ZrS$_x$Se$_{2-x}$ alloys oxidize rapidly, and the oxidation rate
+increases with Se content. Oxidation of basal surfaces is initiated by
+favorable O$_2$ adsorption and proceeds by a mechanism of Zr-O bond switching,
+that collapses the van der Waals gaps, and is facilitated by progressive redox
+transitions of the chalcogen. The rate-limiting process is the formation and
+out-diffusion of SO$_2$. In contrast, MoS$_2$ basal surfaces are stable due to
+unfavorable oxygen adsorption. Our results provide insight and quantitative
+guidance for designing and processing semiconductor devices based on
+ZrS$_x$Se$_{2-x}$ and MoS$_2$, and identify the atomistic-scale mechanisms of
+bonding and phase transformations in layered materials with competing anions.",2007.00117v3
+2018-05-09,Development of nanostructured-graphene-supported silver nanoparticles as catalysts for electroreduction of oxygen in alkaline electrolyte,"Here we develop a class off face centred cubic structure of metallic silver
+nanocrystals, to enable high ORR activity process. Silver nanoparticles
+deposited within different carbon supports: carboxylated-graphene, SiO2-doted
+reduced- graphene-oxide (Gr/SiO2) and reduced-graphene-oxide (Gr) were
+prepared. The reduction of silver ions and the formation of silver
+nanoparticles deposited within graphene-type supports have been assessed by
+UV-Vis spectroscopy and was confirmed by XRD studies. The major advantage of
+the proposed chemical synthetic method is the integration of the superb
+properties of both silver nanoparticles and graphene supports in a single-step
+synthesis with a 100% usage of the silver precursor (AgNO3). The choice of the
+carbon support strongly affected catalytic activity of the resulting Ag
+nanoparticles towards oxygen electroreduction in alkaline medium. We show that
+SiO2-doted reduced- graphene-oxide supported silver nanoparticles display
+significantly enhanced catalytic activity towards the oxygen reduction reaction
+(ORR) in alkaline solutions compared to the silver nanoparticles immobilized
+within carboxylated-graphene support and chemically reduced graphene oxide
+(Gr). Moreover under RRDE conditions the hybrid material based on SiO2-doted
+reduced- graphene-oxide supported silver nanoparticles displays the most
+impressive electrocatalytic performance toward ORR and shows the highest number
+of exchanged electrons (n) ranging from 3.96 to 3.998 when compared to the
+silver nanoparticles immobilized within carboxylated-graphene support
+(3.90-3.994) and reduced-graphene-oxide (Gr) supported silver nanoparticles
+(3.88-3.991).",1805.03389v1
+2012-04-23,Integrating Functional Oxides with Graphene,"Graphene-oxide hybrid structures offer the opportunity to combine the
+versatile functionalities of oxides with the excellent electronic transport in
+graphene. Understanding and controlling how the dielectric environment affects
+the intrinsic properties of graphene is also critical to fundamental studies
+and technological development of graphene. Here we review our recent effort on
+understanding the transport properties of graphene interfaced with
+ferroelectric Pb(Zr,Ti)O_3 (PZT) and high-k HfO_2. Graphene field effect
+devices prepared on high-quality single crystal PZT substrates exhibit up to
+tenfold increases in mobility compared to SiO_2-gated devices. An unusual and
+robust resistance hysteresis is observed in these samples, which is attributed
+to the complex surface chemistry of the ferroelectric. Surface polar optical
+phonons of oxides in graphene transistors play an important role in the device
+performance. We review their effects on mobility and the high source-drain bias
+saturation current of graphene, which are crucial for developing graphene-based
+room temperature high-speed amplifiers. Oxides also introduce scattering
+sources that limit the low temperature electron mobility in graphene. We
+present a comprehensive study of the transport and quantum scattering times to
+differentiate various scattering scenarios and quantitatively evaluate the
+density and distribution of charged impurities and the effect of dielectric
+screening. Our results can facilitate the design of multifunctional
+nano-devices utilizing graphene-oxide hybrid structures.",1204.5161v1
+2017-06-05,"Ultra-small (r<2 nm), stable (>1 year), mixed valence copper oxide quantum dots with anomalous band gap","Ultra-small (r<2 nm) semiconductor quantum dots (QDs) have attracted
+attention for applications ranging from dye sensitized solar cells to sensing
+due to its tunable electronic structure and band gap, and large specific
+surface area. However obtaining monodisperse QDs and stabilization in this size
+regime remains a challenge. A recent report on digestive ripening of an oxide
+system showed substantial promise in addressing these requirements of QDs. In
+this work, we report a green solution, soft chemical (chimie douce) approach
+for synthesis of quasi-spherical, ultra-small, stable, and monodispersed copper
+oxide QDs (r<2 nm) based on digestive ripening (DR). It may be noted this is
+only the second transition metal oxide system in which DR is reported so far.
+DR involves the refluxing of polydispersed colloidal nanoparticles in the
+presence of surface active agents (e.g. triethanolamine (TEA)) that leads to
+fairly monodispersed nanoparticles. It has been noticed that capping with TEA
+results in reduction in the average particle diameter from 6 +/- 4 nm to 2.4
++/- 0.5 nm and an increase of zeta potential ({\xi}) from +12 +/- 2 mV to +31
++/- 2 mV. These copper oxide QDs are monodispersed (size ~ 2.4 +/- 0.5 nm), and
+stable (>1 year). In addition, these quantum dots show an anomalous increase in
+band gap (5.3 eV), inexplicable using Brus' equation. XPS indicates that Cu
+exists in mixed valence state in this material. Based on our observations, we
+suggest that off-stoichiometry in copper oxide, which is seemingly substantial
+at these length scales, is responsible for the observed anomaly in band gap.",1706.01261v1
+2017-12-11,Homolytic Cleavage of Water on Magnesia Film Promoted by Interfacial Oxide-Metal Nanocomposite,"The atomic scale insights into the interaction of water with oxide surface
+are essential for elucidating the mechanism of physiochemical processes in
+various scientific and practical fields, since the water is ubiquitous and
+coats multifarious material surface under ambient conditions. By utilizing
+periodic density functional theory calculations with van der Waals corrections,
+herein we report for the first time the energetically and thermodynamically
+favorable homolytic dissociative adsorption behavior of water over magnesia
+(001) films deposited on metal substrate. The water adsorption on pristine
+magnesia (001) is quite weak and the heterolytic dissociation is the only
+fragmentation pathway, which is highly endothermic with large activation
+barrier of 1.167 eV. The binding strength for the molecular and dissociative
+adsorption configurations of water on hybrid MgO(001) films are significantly
+larger than corresponding configurations on bare magnesia (001). The homolytic
+dissociative adsorption energy of water on monolayer oxide is calculated to be
+-1.192 eV, which is even larger than all the heterolytic dissociative
+adsorption states. With the increase of the oxide thickness, the homolytic
+dissociative adsorption energy decreases promptly, indicating the nanoscale of
+oxide film play a crucial role in homolytic splitting of water. The homolytic
+dissociative adsorption structure could be obtained by transformation reaction
+from heterolytic dissociative adsorption structure, presenting activation
+barriers 0.733, 1.103, 1.306, 1.571, and 1.849 eV for reactions on 1 ML to 5 ML
+films. It is anticipated that the results here could provide inspiring clue and
+versatile strategy for enhancing chemical reactivity and properties of
+insulating oxide toward homolytic water splitting processes involved in novel
+and unprecedented applications.",1712.03762v1
+2017-12-20,Interaction between U/UO2 bilayers and hydrogen studied by in-situ X-ray diffraction,"This paper reports experiments investigating the reaction of H$_{2}$ with
+uranium metal-oxide bilayers. The bilayers consist of $\leq$ 100 nm of
+epitaxial $\alpha$-U (grown on a Nb buffer deposited on sapphire) with a
+UO$_{2}$ overlayer of thicknesses of between 20 and 80 nm. The oxides were made
+either by depositing via reactive magnetron sputtering, or allowing the uranium
+metal to oxidise in air at room temperature. The bilayers were exposed to
+hydrogen, with sample temperatures between 80 and 200 C, and monitored via
+in-situ x-ray diffraction and complimentary experiments conducted using
+Scanning Transmission Electron Microscopy - Electron Energy Loss Spectroscopy
+(STEM-EELS). Small partial pressures of H$_{2}$ caused rapid consumption of the
+U metal and lead to changes in the intensity and position of the diffraction
+peaks from both the UO$_{2}$ overlayers and the U metal. There is an
+orientational dependence in the rate of U consumption. From changes in the
+lattice parameter we deduce that hydrogen enters both the oxide and metal
+layers, contracting the oxide and expanding the metal. The air-grown oxide
+overlayers appear to hinder the H$_{2}$-reaction up to a threshold dose, but
+then on heating from 80 to 140 C the consumption is more rapid than for the
+as-deposited overlayers. STEM-EELS establishes that the U-hydride layer lies at
+the oxide-metal interface, and that the initial formation is at defects or
+grain boundaries, and involves the formation of amorphous and/or
+nanocrystalline UH$_{3}$. This explains why no diffraction peaks from UH$_{3}$
+are observed. {\textcopyright British Crown Owned Copyright 2017/AWE}",1712.07387v1
+2019-10-09,Surface-charge-mediated Formation of H-TiO2@Ni(OH)2 Heterostructures for High-Performance Supercapcitors,"Supercapacitors or ultracapacitors are promising for efficient energy storage
+applications, owing to their high power density, high charge-discharge rates,
+and long cycle life performance. To achieve this goal, a large specific surface
+area, an high electronic conductivity and a fast cation intercalation
+de-intercalation process are generally required in the design and preparation
+of materials for high-performance supercapacitors. Recently, core-shell
+heterostructures with multifunctionalities are regarded as one of promising
+materials for supercapacitors or ultracapacitors applications. In particular,
+one-dimensional (1D) core-shell heterostructures have sparked great scientific
+and technological interests due to their high versatility and applicability as
+the essential components in nanoscale electronics, catalysis, chemical sensing,
+and energy conversion storage devices. Various metal metal oxide, metal metal,
+metal oxide metal oxide and metal oxide conductive polymers so far have been
+investigated. Transition metal hydroxide oxide Co3O4, Co(OH)2, MnO2, Mn(OH)2,
+NiO, Ni(OH)2 and their compounds storing energy by surface faradaic (redox)
+reactions were generally integrated with conducting scaffold to build
+core-shell structure. Intensive studies show that an enlarged active surface
+area of transition metal hydroxide oxide enables a promoted surface redox
+reaction and enhanced electrochemical performance. Therefore, controllable
+synthesis of a hierarchically porous construction with high surface areas is
+critically important for energy storage.",1910.03813v1
+2019-10-29,Nickel oxide-based heterostructures with large band offsets,"We present research results on the electronic transport in heterostructures
+based on p-type nickel oxide (NiO) with the n-type oxide semiconductors zinc
+oxide (ZnO) and cadmium oxide (CdO). NiO is a desirable candidate for
+application in (opto-)electronic devices. However, because of its small
+electron affinity, heterojunctions with most n-type oxide semiconductors
+exhibit conduction and valence band offsets at the heterointerface in excess of
+1 eV. ZnO/NiO junctions exhibit a so called type-II band alignment, making
+electron-hole recombination the only process by which a current can vertically
+flow through the structure. These heterojunctions are nevertheless shown to be
+of practical use in efficient optoelectronic devices, as exemplified here by
+our UV-converting transparent solar cells. These devices, although exhibiting
+high conversion efficiencies, suffer from two light-activated recombination
+channels connected to the type-II interface, one of which we identify and
+analyse in more detail here. Furthermore, CdO/NiO contacts were studied - a
+heterostructure with even larger band offsets such that a type-III band
+alignment is achieved. This situation theoretically enables the development of
+a 2-dimensional electronic system consisting of topologically protected states.
+We present experiments demonstrating that the CdO/NiO heterostructure indeed
+hosts a conductive layer absent in both materials when studied separately.",1910.13169v1
+2020-12-19,H$_2$O$_2$-induced Greenhouse Warming on Oxidized Early Mars,"The existence of liquid water within an oxidized environment on early Mars
+has been inferred by the Mn-rich rocks found during recent explorations on
+Mars. The oxidized atmosphere implied by the Mn-rich rocks would basically be
+comprised of CO$_2$ and H$_2$O without any reduced greenhouse gases such as
+H$_2$ and CH$_4$. So far, however, it has been thought that early Mars could
+not have been warm enough to sustain water in liquid form without the presence
+of reduced greenhouse gases. Here, we propose that H$_2$O$_2$ could have been
+the gas responsible for warming the surface of the oxidized early Mars. Our
+one-dimensional atmospheric model shows that only 1 ppm of H$_2$O$_2$ is enough
+to warm the planetary surface because of its strong absorption at far-infrared
+wavelengths, in which the surface temperature could have reached over 273~K for
+a CO$_2$ atmosphere with a pressure of 3~bar. A wet and oxidized atmosphere is
+expected to maintain sufficient quantities of H$_2$O$_2$ gas in its upper
+atmosphere due to its rapid photochemical production in slow condensation
+conditions. Our results demonstrate that a warm and wet environment could have
+been maintained on an oxidized early Mars, thereby suggesting that there may be
+connections between its ancient atmospheric redox state and possible aqueous
+environment.",2012.10616v2
+2018-08-05,Apparatus for Operando X-ray Diffraction of Fuel Electrodes in High Temperature Solid State Electrochemical Cells,"Characterizing electrochemical energy conversion devices during operation is
+an important strategy for correlating device performance with the properties of
+cell materials under real operating conditions. While operando characterization
+has been used extensively for low temperature electrochemical cells, these
+techniques remain challenging for solid oxide electrochemical cells due to the
+high temperatures and reactive gas atmospheres these cells require. Operando
+X-ray diffraction measurements of solid oxide electrochemical cells could
+detect changes in the crystal structure of the cell materials, which can be
+useful for understanding degradation process that limit device lifetimes, but
+the experimental capability to perform operando X-ray diffraction on the fuel
+electrodes of these cells has not been demonstrated. Here we present the first
+experimental apparatus capable of performing X-ray diffraction measurements on
+the fuel electrodes of high temperature solid oxide electrochemical cells
+during operation under reducing gas atmospheres. We present data from an
+example experiment with a model solid oxide cell to demonstrate that this
+apparatus can collect X-ray diffraction spectra during electrochemical cell
+operation at high temperatures in humidified H2 gas. Measurements performed
+using this apparatus can reveal new insights about solid oxide fuel cell and
+solid oxide electrolyzer cell degradation mechanisms to enable the design of
+durable, high performance devices.",1808.01551v1
+2020-08-19,Polymer coated cerium oxide nanoparticles as oxidoreductase-like catalysts,"Cerium oxide nanoparticles have been shown to mimic oxidoreductase enzymes by
+catalyzing the decomposition of organic substrates and reactive oxygen species.
+This mimicry can be found in superoxide radicals and hydrogen peroxides,
+harmful molecules produced in oxidative stress asso-ciated diseases. Despite
+the fact that nanoparticle functionalization is mandatory in the context of
+nanomedicine, the influence of polymer coatings on their enzyme-like catalytic
+activity is poorly understood. In this work, six polymer coated cerium oxide
+nanoparticles are prepared by associa-tion of 7.8 nm cerium oxide cores with
+two poly(sodium acrylate) and four poly(ethylene glycol) (PEG) grafted
+copolymers with different terminal or anchoring end groups, such as phosphonic
+acids. The superoxide dismutase-, catalase-, peroxidase- and oxidase-like
+catalytic activities of the coated nanoparticles were systematically studied.
+It is shown that the polymer coatings do not af-fect the superoxide
+dismutase-like, impair the catalase-like and oxidase-like and surprisingly
+im-proves peroxidase-like catalytic activities of cerium oxide nanoparticles.
+It is also demonstrated that the particles coated with the PEG-grafted
+copolymers perform better than the poly(acrylic acid) coated ones as
+oxidoreductase-like enzymes, a result that confirms the benefit of having
+phosphon-ic acids as anchoring groups at the particle surface.",2008.08492v1
+2020-08-28,Precursor Selection in Hybrid Molecular Beam Epitaxy of Alkaline-Earth Stannates,"One of the challenges of oxide molecular beam epitaxy (MBE) is the synthesis
+of oxides containing metals with high electronegativity (metals that are hard
+to oxidize). The use of reactive organometallic precursors can potentially
+address this issue. To investigate the formation of radicals in MBE, we
+explored three carefully chosen metal-organic precursors of tin for SnO2 and
+BaSnO3 growth: tetramethyltin (TMT), tetraethyltin (TET), and hexamethylditin
+(HMDT). All three precursors produced single-crystalline, atomically smooth,
+and epitaxial SnO2 (101) films on r-Al2O3 in the presence of an oxygen plasma.
+The study of growth kinetics revealed reaction-limited and flux-limited regimes
+except for TET, which also exhibited a decrease in deposition rate with
+increasing temperature above 800 C. Contrary to these similarities, the
+performance of these precursors was dramatically different for BaSnO3 growth.
+TMT and TET were ineffective in supplying adequate tin whereas HMDT yielded
+phase-pure, stoichiometric BaSnO3 films. Significantly, HMDT resulted in
+phase-pure and stoichiometric BaSnO3 films even without the use of an oxygen
+plasma (i.e., with molecular oxygen alone). These results are discussed using
+the ability of HMDT to form tin radicals and therefore, assisting with Sn to
+Sn4+ oxidation reaction. Structural and electronic transport properties of
+films grown using HMDT with and without oxygen plasma are compared. This study
+provides guideline for the choice of precursors that will enable synthesis of
+metal oxides containing hard-to-oxidize metals using reactive radicals in MBE.",2008.12762v1
+2021-03-17,Advanced Raman spectroscopy detection of oxidative damage in nucleic acid bases: probing chemical changes and intermolecular interactions in guanosine at ultralow concentration,"DNA/RNA synthesis precursors are especially vulnerable to damage induced by
+reactive oxygen species occurring following oxidative stress. Guanosine
+triphosphates are the prevalent oxidized nucleosites, which can be
+misincorporated during replication, leading to mutations and cell death. Here,
+we present a novel method based on micro-Raman spectroscopy, combined with ab
+initio calculations, for the identification, detection, and quantification of
+low concentrations of oxidized nucleotides. We also show that the Raman
+signature in the terahertz spectral range (< 100 cm$^{-1}$) contains
+information on the intermolecular assembly of guanine in tetrads, which allows
+to further boost the oxidative damage detection limit. Eventually, we provide
+evidence that similar analyses can be carried out on samples in very small
+volumes at very low concentrations by exploiting the high sensitivity of
+Surface Enhanced Raman Scattering combined with properly designed
+superhydrophobic substrates. These results pave the way for employing such
+advanced spectroscopic methods for quantitatively sensing the oxidative damage
+of nucleotides in the cell.",2103.09524v1
+2021-04-02,Fluxional Behavior at the Atomic Level and its Impact on Activity: CO Oxidation over CeO$_{2}$-supported Pt Catalysts,"Reducible oxides are widely used catalyst supports that can increase
+oxidation reaction rates by transferring their lattice oxygen at the
+metal-support interface. The interfacial oxidation process is typically
+described in terms of a Mars-van Krevelen mechanism. However, many outstanding
+questions remain unanswered regarding the atomic-scale structure and dynamic
+meta-stability (i.e., fluxional behavior) of the interface $\textit{during
+catalysis}$. Here, we employ aberration-corrected $\textit{operando}$ electron
+microscopy to visualize the structural dynamics occurring at and near
+Pt/CeO$_{2}$ interfaces during CO oxidation. Finite element simulations are
+performed to develop a reaction rate analysis wherein the atomic-level
+structural observations are directly correlated with the catalyst's turnover
+frequency for CO oxidation. We show that the increasing frequency of catalytic
+turnover correlates with dynamic fluxional behavior that (a) destablizes the
+supported Pt particle, (b) marks an enhanced rate of oxygen vacancy creation
+and annihilation, and (c) leads to increased strain and reduction in the
+surface of the CeO$_{2}$ support. Overall, the results implicate the
+interfacial Pt-O-Ce bonds anchoring the Pt to the support as being involved
+also in the catalytically-driven oxygen transfer process, and they suggest that
+oxygen reduction takes place on the highly reduced nearby CeO2 surface before
+migrating to the interfacial perimeter for reaction with CO. The
+$\textit{operando}$ electron microscopy approach described here should be
+applicable to a large number of nanoparticle catalysts. This technique will
+enable the identification of catalytically functional surface structures and
+strengthen our ability to establish (dynamic) structure-activity relationships.",2104.00821v1
+2021-06-08,Insights into the Coadsorption and Reactivity of O and CO on Ru(0001) and Their Coverage Dependence,"Using density functional theory and an exchange-correlationfunctional that
+includes the van der Waals interaction, we study the coadsorption of CO on
+Ru(0001) saturated with 0.5 ML of oxygen. Different coexisting CO coverages are
+considered that are experimentally motivated, the room temperaturecoverage
+consisting of 0.5 ML-O + 0.25 ML-CO (low coverage), the saturation coverage
+achieved at low temperatures (0.5 ML-O + 0.375 ML-CO, intermediate coverage),
+and the equally mixed monolayer that is stable according to our calculations
+but not experimentally observed yet (0.5 ML-O + 0.5 ML-CO, high coverage). For
+each coverage, we study the competition between the desorption and oxidation of
+CO on the corresponding optimized structure by analyzing their reaction
+energies and minimum energy reaction paths. The desorption process is
+endothermic at all coverages, although the desorption energy decreases as the
+CO coverage increases. The process itself (and also the reverted adsorption)
+becomes more involved at the intermediate and high coverages because of the
+appearance of a physisorption well and concomitant energy barrier separating it
+from the chemisorbed state. Remarkably, the oxidation of CO, which is
+endothermic at low coverages, turns exothermic at the intermediate and high
+coverages. In all cases, the minimum reaction path for oxidation, which
+involves the chemisorbed and physisorbed CO2, is ruled by one of the large
+energy barriers that protect these molecular states. Altogether, the larger
+activation energies for oxidation as compared to those for desorption and the
+extreme complexity of the oxidation against the desorption paths explain that
+CO desorption dominates over the oxidation in experiments.",2106.04234v1
+2021-10-22,Thermal conductivity of oxide scale and its components in the range from 0 C to 1300 C: Generalized estimates with account for movability of phase transitions,"The data of different authors on the thermal conductivity of wustite Fe1-xO,
+magnetite F3O4, hematite Fe2O3 and pure iron are systematized. The generalized
+values are described by piecewise smooth functions containing as varying
+parameters the temperatures of magnetiv and polymorphic (for iron)
+transformations as well as the thermodynamic stability boundary (for wustite).
+At polymorphic transformation a finite break of the thermal conductivity
+function is envisaged, at othet critical points only a break of its temperature
+derivative is acceptable. The proposed formulas are presented in two forms: the
+general form that allow varying the values of critical temperatures and the
+particular form corresponding to their basic values: the boundary of
+thermodynamic stability of wustite - 570 C, the Curie points of magnetite - 575
+C, hematite - 677 C, iron - 770 C and polymorphic transformation temperature of
+iron - 912 C. To calculate the thermal conductivity of oxide scale as a whole,
+it is proposed to take into account separately metallic iron and composite
+matrix of iron oxides. Model computations using the proposed formulas shows
+that the true thermal conductivity of oxide scale (without pores), depending on
+the temperature may be from 3 to 6 W / (m K) in the absence of metallic iron
+and up to 15 W / (m K) if free iron is released in the eutectoid decay of
+wustite. The effective thermal conductivity of oxide scale, taking into account
+its real porosity, may be lower by 15-35%. The obtained dependencies are
+recommended for use in mathematical simulation of production and processing of
+steel products in the presence of oxide scale on their surface.",2110.11632v1
+2021-11-02,Structure and motifs of iron oxides from 1 to 3 TPa,"Iron oxides are fundamental components of planet-forming materials.
+Understanding the Fe-O system's behavior and properties under high pressure can
+help us identify many new phases and states possible in exoplanetary interiors,
+especially terrestrial ones. Using the adaptive genetic algorithm (AGA), we
+investigate the structure of iron oxides for a wide range of stoichiometries
+($0.25\leq x_O \leq 0.8$) at 1, 2, and 3 TPa. Five unreported ground-state
+structures with Fe$_2$O, FeO, Fe$_3$O$_5$, FeO$_2$, and FeO$_4$ compositions
+are identified. The calculated density of states (DOS) suggests that, except
+for FeO$_4$, all phases are metallic, but their carrier densities decrease with
+increasing pressure and oxygen content. The cluster alignment analysis of
+stable and metastable phases shows that several motifs may co-exist in a
+structure of iron oxides with low O content. In contrast, most iron oxides with
+high O content adopt a simple BCC motif at TPa pressures. Our results provide a
+crystal structure database of iron oxides for modeling and understanding the
+interiors of exoplanets.",2111.01305v2
+2021-11-29,Modeling of nucleobase/oligonucleotide interaction with graphene and graphene oxide: the role of charging and/or oxidizing the graphene surface,"We analyze the influence of the charge and the degree of oxidation of the
+surface of graphene (Gr) on its interaction with cytosine and oligonucleotide
+r(C)10. This is a computational study involving DFT calculations and molecular
+dynamics simulations. It is shown that cytosine interacts stronger with
+graphene oxide (GO) than with Gr, while the energy of the interaction of
+cytosine with GO only weakly depends on the degree of the Gr oxidation. A
+correlation between the shifts of vibrational frequencies of cytosine due to
+complexation with GO and the degree of the Gr oxidation is found. The
+adsorption of anionic oligonucleotide r(C)10 onto neutral and positively
+charged surfaces has a certain conformational similarity to conformations
+formed with similar van der Waals interactions. Also, for charged surfaces, the
+Coulombic attraction gives a noticeable contribution to the total interaction
+energy. For a negatively charged graphene surface the electrostatic repulsion
+between Gr surface and negatively charged phosphate backbone of oligonucleotide
+weakens the total binding energy. Competition between the Coulombic repulsion
+and the van der Waals attraction results in formation of a unique
+oligonucleotide conformation where all 10 cytosines are stacked onto Gr.",2111.14435v1
+2022-01-06,Chemically edge-carboxylated graphene enhances thermal conductivity of polyetherimide-graphene nanocomposites,"In this work, we demonstrate that edge-oxidation of graphene can enable
+larger enhancement in thermal conductivity (k) of graphene-nanoplatelet
+(GnP)/polyetherimide (PEI) composites relative to oxidation of the basal plane
+of graphene. Edge oxidation (EGO) offers the advantage of leaving the basal
+plane of graphene intact, preserving its high in-plane thermal conductivity
+(kin > 2000 Wm-1K-1), while, simultaneously, the oxygen groups introduced on
+graphene edge enhance interfacial thermal conductance through hydrogen bonding
+with oxygen groups of polyetherimide (PEI), enhancing overall polymer composite
+thermal conductivity. Edge oxidation is achieved in this work, by oxidizing
+graphene in presence of sodium chlorate and hydrogen peroxide, introducing
+carboxyl groups on the edge of graphene. Basal-plane oxidation of graphene
+(BGO), on the other hand, achieved through Hummers method, distorts sp2
+carbon-carbon network of graphene, dramatically lowering its intrinsic thermal
+conductivity, causing the BGO/PEI composite k to be even lower than pristine
+GnP/PEI composite k value. The resulting thermal conductivity of EGO/PEI
+composite is found to be enhanced by 18%, whereas that of BGO/PEI composite is
+diminished by 57%, with respect to pristine GnP/PEI composite for 10 weight%
+GnP content. 2-dimensional Raman mapping of graphene nanoplatelets is used to
+confirm and distinguish the location of oxygen functional groups on graphene.
+The superior effect of edge bonding presented in this work can lead to
+fundamentally novel pathways for achieving high thermal conductivity polymer
+composites.",2201.03395v2
+2022-01-19,Simulations of the Electrochemical Oxidation of Pt Nanoparticles of Various Shapes,"The activity and stability of a platinum nanoparticle (NP) is not only
+affected by its size but additionally depends on its shape. To this end,
+simulations can identify structure-property relationships to make a priori
+decisions on the most promising structures. While activity is routinely probed
+by electronic structure calculations on simplified surface models, modeling the
+stability of NP model systems in electrochemical reactions is challenging due
+to the long timescale of relevant processes such as oxidation beyond the point
+of reversibility. In this work, a routine for simulating electrocatalyst
+stability is presented. The procedure is referred to as GREG after its main
+ingredients - a grand-canonical simulation approach using reactive force fields
+to model electrochemical reactions as a function of the galvanic cell
+potential. The GREG routine is applied to study the oxidation of 3 nm
+octahedral, cubic, dodecahedral, cuboctahedral, spherical, and tetrahexahedral
+platinum NPs. The oxidation process is analyzed using adsorption isobars as
+well as interaction energy heat maps that provide the basis for constructing
+electrochemical phase diagrams. Onset potentials for surface oxidation increase
+in the sequence cube ~= dodecahedron <= octahedron <= tetrahexahdron < sphere <
+cuboctahedron, establishing a relationship between oxidation behavior and
+surface facet structure. The electrochemical results are rationalized using
+structural and electronic analysis.",2201.07605v2
+2022-01-27,Hubbard-corrected oxide formation enthalpies without adjustable parameters,"A density functional theory (DFT) approach to computing transition metal
+oxide heat of formation without adjustable parameters is presented. Different
+degrees of $d$-electron localization in oxides are treated within the DFT+$U$
+approach with site-dependent, first-principles Hubbard $U$-parameters obtained
+from linear response theory, and delocalized states in the metallic phases are
+treated without Hubbard corrections. Comparison of relative stabilities of
+these differently treated phases is enabled by a local $d$-electron density
+matrix-dependent model, which was found by genetic programming against
+experimental reference formation enthalpies. This mathematically simple model
+does not explicitly depend on the Hubbard-corrected ionic species and is shown
+to reproduce the heats of formation of the Mott insulators Ca$_2$RuO$_4$ and
+Y$_2$Ru$_2$O$_7$ within $\sim$3% of experimental results, where the
+experimental training data did not contain Ru oxides. This newly developed
+method thus absolves from the need for element-specific corrections fitted to
+experiments in existing Hubbard-corrected approaches to the prediction of
+reaction energies of transition metal oxides and metals. The absence of fitting
+parameters opens up here the possibility to predict relative thermodynamic
+stabilities and reaction energies involving $d$-states of varying degree of
+localization at transition metal oxide interfaces and defects, where
+site-dependent $U$-parameters will be particularly important and devising a
+fitting scheme against experimental data with predictive power would be
+exceedingly difficult.",2201.11644v2
+2022-08-29,Multi Spectral Switchable Infra-Red Reflectance Resonances in Highly Subwavelength Partially Oxidized Vanadium Thin Films,"Phase transition materials are promising for realization of switchable
+optics. In this work, we show reflectance resonances in the near-infrared and
+long-wave infrared wavelengths in highly subwavelength partially oxidized
+Vanadium thin films. These partially oxidized films consist of a multilayer of
+Vanadium dioxide and Vanadium as shown using Raman spectroscopy and four-probe
+measurements. As Vanadium dioxide is a phase transition material that shows
+insulator to metal phase transition at 68 C, the observed infra-red resonances
+can be switched with temperature into a high-reflectance state. The wavelength
+of these resonances are passively tunable as a function of the oxidation
+duration. The obtained reflectance resonance at near-infrared wavelength red
+shifts from 1.78 um to 2.68 um with increasing oxidation duration while the
+long-wavelength infrared resonance blue shifts from 12.68 um to 9.96 um. To
+find the origin of the reflectance resonances, we model the reflectance spectra
+as a function of the oxidation duration using the transfer matrix method. The
+presented model captures the dual reflectance resonances reasonably well. These
+passive wavelength-tunable and switchable resonances with easy to fabricate
+lithography-free multilayer structure will be useful for multispectral
+applications such as camouflage, spectral selective microbolometer, and thermal
+management.",2208.13458v1
+2022-09-22,Tuning SMSI Kinetics on Pt-loaded TiO$_2$(110) by Choosing the Pressure: A Combined UHV / Near-Ambient Pressure XPS Study,"Pt catalyst particles on reducible oxide supports often change their activity
+significantly at elevated temperatures due to the strong metal-support
+interaction (SMSI), which induces the formation of an encapsulation layer
+around the noble metal particles. However, the impact of oxidizing and reducing
+treatments at elevated pressures on this encapsulation layer remains
+controversial, partly due to the 'pressure gap' between surface science studies
+and applied catalysis. In the present work, we employ synchrotron-based
+near-ambient pressure X-ray photoelectron spectroscopy (NAP-XPS) to study the
+effect of O$_2$ and H$_2$ on the SMSI-state of well-defined Pt/TiO$_2$(110)
+catalysts at pressures of up to 0.1 Torr. By tuning the O$_2$ pressure, we can
+either selectively oxidize the TiO$_2$ support or both the support and the Pt
+particles. Catalyzed by metallic Pt, the encapsulating oxide overlayer grows
+rapidly in 1x10$^{-5}$ Torr O$_2$, but orders of magnitudes less effective at
+higher O$_2$ pressures, where Pt is in an oxidic state. While the
+oxidation/reduction of Pt particles is reversible, they remain embedded in the
+support once encapsulation has occurred.",2209.10971v1
+2023-01-11,Defect engineering over anisotropic brookite towards substrate-specific photo-oxidation of alcohols,"Generally adopted design strategies for enhancing the photocatalytic activity
+are aimed at tuning properties such as the visible light response, the exposed
+crystal facets, and the nanocrystal shape. Here, we present a different
+approach for designing efficient photocatalysts displaying a substrate-specific
+reactivity upon defect engineering. The defective anisotropic brookite TiO2
+photocatalyst functionalized with Pt nanocrystals are tested for alcohol
+photoreforming showing up to an 11-fold increase in methanol oxidation rate,
+compared to the unreduced one, whilst presenting much lower ethanol or
+isopropanol specific oxidation rates. We demonstrate that the alcohol oxidation
+and hydrogen evolution reactions are tightly related, and when the
+substrate-specific alcohol oxidation ability is increased, the hydrogen
+evolution is significantly boosted. The reduced anisotropic brookite shows up
+to twenty-six-fold higher specific photoactivity with respect to anatase and
+brookite with isotropic nanocrystals, reflecting the different type of
+defective catalytic sites formed depending on the TiO2 polymorph and its
+crystal shape. Advanced in-situ characterizations and theoretical
+investigations reveal that controlled engineering over oxygen vacancies and
+lattice strain produces large electron polarons hosting the substrate-specific
+active sites for alcohol photo-oxidation.",2301.04375v1
+2023-01-27,Machine-guided Design of Oxidation Resistant Superconductors for Quantum Information Applications,"Decoherence in superconducting qubits has long been attributed to two level
+systems arising from the surfaces and interfaces present in real devices. A
+recent significant step in reducing decoherence was the replacement of
+superconducting niobium by superconducting tantalum, resulting in a tripling of
+transmon qubit lifetimes (T1). One of these surface variables, the identity,
+thickness, and quality of the native surface oxide, is thought to play a major
+role as tantalum only has one oxide whereas niobium has several. Here we report
+the development of a thermodynamic metric to rank materials based on their
+potential to form a well-defined, thin, surface oxide. We first compute this
+metric for known binary and ternary metal alloys using data available from
+Materials Project, and experimentally validate the strengths and limits of this
+metric through preparation and controlled oxidation of 8 known metal alloys.
+Then we train a convolutional neural network to predict the value of this
+metric from atomic composition and atomic properties. This allows us to compute
+the metric for materials that are not present in materials project, including a
+large selection of known superconductors, and, when combined with Tc, allow us
+to identify new candidate superconductors for quantum information science
+(QISE) applications. We test the oxidation resistance of a pair of these
+predictions experimentally. Our results are expected to lay the foundation for
+tailored and rapid selection of improved superconductors for QISE.",2301.11543v1
+2023-02-13,A computational model for the design of a nitrous oxide--paraffin wax hybrid rocket engine,"A computational model is developed to assist the design of the first hybrid
+rocket engine of the McGill Rocket Team, using liquid nitrous oxide as an
+oxidizer and solid paraffin wax as a fuel. The model is developed in three
+phases: In the first phase, a steady-state model which neglects transient
+performance decrease of the hybrid engine is considered. The steady-state model
+considers: a constant oxidizer mass flow rate; a combustion chamber in chemical
+equilibrium; a one-dimensional isentropic nozzle; and a one-dimensional
+constant-thrust rocket ascent. The steady-state model is used to conduct
+parametric studies on engine performance as a function of design parameters
+such as: oxidizer mass flow rate, fuel grain dimensions, and nozzle dimensions.
+The engine design point is selected to optimize specific impulse, given
+physical and structural constraints of the system. In the second phase, an
+unsteady model incorporating transient performance decrease of the hybrid
+engine is considered. The transient model considers: a self-pressurizing
+oxidizer tank in quasi-steady liquid-vapor equilibrium; a combustion chamber in
+quasi-steady chemical equilibrium; a one-dimensional non-isentropic nozzle; and
+a one-dimensional rocket ascent model. The transient performance profile of the
+engine is established, and the unsteady model is used to predict propellant
+requirements for the launch vehicle, given a target apogee of 3048 m (10,000
+ft). In the third stage, the unsteady model is compared to hot fire testing
+data of the McGill Rocket Team. Semi-empirical parameters used in the
+formulation are calibrated against testing data, and the validity of the model
+is assessed.",2302.06725v1
+2023-03-14,Chemical and structural characterization of the native oxide scale on a Mg-based alloy,"In this study, the structure and composition of the native oxide forming on
+the basal plane (0001) of Mg-2Al-0.1Ca is investigated by a correlative
+approach, combining scanning transmission electron microscopy (STEM) and atom
+probe tomography (APT). Atom probe specimens were prepared conventionally in a
+Ga focused ion beam (FIB) as well as a Xe plasma FIB in a cryogenic setup and
+subsequently cleaned in the atom probe to remove surface contamination before
+oxidation. While thermal energy input from the laser and longer atmospheric
+exposure time increased the measured hydrogen content in the specimen's apex
+region, cryo preparation revealed, that the hydrogen uptake in magnesium is
+independent of the employment of conventional or cryogenic FIB preparation. TEM
+measurements demonstrated the growth of a (111) MgO oxide layer with 3-4 nm
+thickness on the basal (0001) plane of the Mg atom probe specimen. APT data
+further revealed the formation of an aluminum-rich region between bulk Mg and
+the native oxide. The aluminum enrichment of up to ~20 at.% at the interface is
+consistent with an inward growth of the oxide scale.",2303.07763v3
+2023-04-05,Effects of molecular contamination and sp$^2$ carbon on oxidation of (100) single-crystal diamond surfaces,"The efficacy of oxygen (O) surface terminations of specific moieties and
+densities on diamond depends on factors such as crystallinity, roughness, and
+crystal orientation. Given the wide breadth of diamond-like materials and
+O-termination techniques, it can be difficult to discern which method would
+yield the highest and most consistent O coverage on a particular subset of
+diamond. We first review the relevant physical parameters for O-terminating
+single-crystalline diamond (SCD) surfaces and summarize prior oxidation work on
+(100) SCD. We then report on our experimental study on X-ray Photoelectron
+Spectroscopy (XPS) characterization of (100) diamond surfaces treated with
+oxidation methods that include wet chemical oxidation, photochemical oxidation
+with UV illumination, and steam oxidation using atomic layer deposition. We
+describe a rigorous XPS peak-fitting procedure for measuring the
+functionalization of O-terminated samples and recommend that the reporting of
+peak energy positions, line shapes, and full-width-half-maximum values of the
+individual components, along with the residuals, are important for evaluating
+the quality of the peak fit. Two chemical parameters on the surface, sp$^2$ C
+and molecular contaminants, are also crucial towards interpreting the O
+coverage on the diamond surface and may account for the inconsistency in prior
+reported values in literature.",2304.02217v1
+2023-05-04,"Surface oxides, carbides, and impurities on RF superconducting Nb and Nb3Sn: A comprehensive analysis","Surface structures on radio-frequency (RF) superconductors are crucially
+important in determining their interaction with the RF field. Here we
+investigate the surface compositions, structural profiles, and valence
+distributions of oxides, carbides, and impurities on niobium (Nb) and
+niobium-tin (Nb3Sn) in situ under different processing conditions. We establish
+the underlying mechanisms of vacuum baking and nitrogen processing in Nb and
+demonstrate that carbide formation induced during high-temperature baking,
+regardless of gas environment, determines subsequent oxide formation upon air
+exposure or low-temperature baking, leading to modifications of the electron
+population profile. Our findings support the combined contribution of surface
+oxides and second-phase formation to the outcome of ultra-high vacuum baking
+(oxygen processing) and nitrogen processing. Also, we observe that
+vapor-diffused Nb3Sn contains thick metastable oxides, while electrochemically
+synthesized Nb3Sn only has a thin oxide layer. Our findings reveal fundamental
+mechanisms of baking and processing Nb and Nb3Sn surface structures for
+high-performance superconducting RF and quantum applications",2305.02467v2
+2023-05-17,Synthesis of stable cerium oxide nanoparticles coated with phosphonic acid-based functional polymers,"Functional polymers, such as poly(ethylene glycol) (PEG) terminated with a
+single phosphonic acid, hereafter PEGik-Ph are often applied to coat metal
+oxide surfaces during post synthesis steps, but are not sufficient to stabilize
+sub-10 nm particles in protein-rich biofluids. The instability is attributed to
+the weak binding affinity of post-grafted phosphonic acid groups, resulting in
+a gradual detachment of the polymers the surface. Here, we assess these
+polymers as coating agents using an alternative route, namely the one-step
+wet-chemical synthesis, where PEGik-Ph is introduced with cerium precursors
+during the synthesis. Characterization of the coated cerium oxide nanoparticles
+indicates a core-shell structure, where the cores are 3 nm cerium oxide and the
+shell consists of functionalized PEG polymers in a brush configuration. Results
+show that cerium oxide nanoparticles coated with PEG1k-Ph and PEG2k-Ph are of
+potential interest for applications as nanomedicine due to their high Ce(III)
+content and increased colloidal stability in cell culture media. We further
+demonstrate that the cerium oxide nanoparticles in the presence of hydrogen
+peroxide show an additional absorbance band in the UV-vis spectrum, which is
+attributed to Ce-O22- peroxo-complexes and could be used in the evaluation of
+their catalytic activity for scavenging reactive oxygen species.",2305.10179v1
+2023-12-15,Tunable 2D Electron- and 2D Hole States Observed at Fe/SrTiO$_3$ Interfaces,"Oxide electronics provide the key concepts and materials for enhancing
+silicon-based semiconductor technologies with novel functionalities. However, a
+basic but key property of semiconductor devices still needs to be unveiled in
+its oxidic counterparts: the ability to set or even switch between two types of
+carriers - either negatively (n) charged electrons or positively (p) charged
+holes. Here, we provide direct evidence for individually emerging n- or p-type
+2D band dispersions in STO-based heterostructures using resonant photoelectron
+spectroscopy. The key to tuning the carrier character is the oxidation state of
+an adjacent Fe-based interface layer: For Fe and FeO, hole bands emerge in the
+empty band gap region of STO due to hybridization of Ti and Fe-derived states
+across the interface, while for Fe$_3$O$_4$ overlayers, an 2D electron system
+is formed. Unexpected oxygen vacancy characteristics arise for the hole-type
+interfaces, which as of yet had been exclusively assigned to the emergence of
+2DESs. In general, this finding opens up the possibility to straightforwardly
+switch the type of conductivity at STO interfaces by the oxidation state of a
+redox overlayer. This will extend the spectrum of phenomena in oxide
+electronics, including the realization of combined n/p-type all-oxide
+transistors or logic gates.",2312.09798v1
+2024-03-25,Facile synthesis of CoSi alloy with rich vacancy for base- and solvent-free aerobic oxidation of aromatic alcohols,"Rational design and green synthesis of low-cost and robust catalysts
+efficient for the selective oxidation of various alcohols are full of
+challenges. Herein, we report a fast and solvent-free arc-melting (AM) method
+to controllably synthesize semimetal CoSi alloy (abbreviated as AM-CoSi) that
+is efficient for the base- and solvent-free oxidation of six types of aromatic
+alcohols. X-ray absorption fine structure (XAFS), electron paramagnetic
+resonance (EPR), and aberration corrected high angle annular dark field
+scanning transmission electron microscope (AC HAADF-STEM) confirmed the
+successful synthesis of AM-CoSi with rich Si vacancy (Siv). The as-prepared
+CoSi alloy catalysts exhibit an order of magnitude activity enhancement in the
+oxidation of model reactant benzyl alcohol (BAL) to benzyl benzoate (BBE)
+compared with its mono counterparts, whereas 70 % yield of BBE which is the
+highest yield to date. Experimental results and DFT calculations well verify
+that the CoSi alloy structure improves the BAL conversion and Si vacancy mainly
+contributes to the generation of BBE. After that, CoSi alloy maintains high
+stability and a potential pathway is rationally proposed. Besides, CoSi alloy
+also efficiently works for the selective oxidation of various alcohols with
+different groups. This work demonstrates for the first time that semimetal CoSi
+alloy is robust for the green oxidation of various alcohols and provides a vast
+opportunity for reasonable design and application of other semimetal alloy
+catalysts.",2403.16708v1
+2024-04-04,Modeling of Zircaloy Oxidation Through Dynamic Mesh Deformation,"Zircaloy cladding corrosion in Light Water Reactors (LWRs) results in the
+formation of an outer oxide layer and in the thinning of the metallic portion
+of the cladding. At the \'Ecole Polytechnique F\'ed\'erale de Lausanne (EPFL),
+we aim to investigate the impact of asymmetric oxide or crud layers and their
+feedback on thermal-hydraulics. To achieve this, we are implementing
+mechanistic capabilities for the treatment of corrosion within the open-source
+multi-dimensional code OFFBEAT. In this work, we outline our approach based on
+the combination of traditional laws for predicting the growth of the oxide
+layer with methods to dynamically modify the mesh points and topology.
+Specifically, our methodology employs routines available in the OpenFOAM
+library to add or remove layers of cells according to the growth of the oxide
+layer, along with a mesh motion solver to maintain mesh quality. We verify the
+methodologys against an analytical test case and then we demonstrate its
+potential for the study of non-uniform oxide distributions by modeling a
+simplified cladding ring with asymmetric temperature profile, mimicking the
+conditions of azimuthal power peaking in a Boiling Water Reactor (BWR).",2404.03454v1
+1997-08-22,Theory of Photoemission from the Copper Oxide Material,"A mean-field theory which satisfying the electron on-site local constraint in
+the relevant regime of density for the high temperature superconductors is
+developed. Within this approach, the electron spectral function, the electron
+dispersion, and the electron density of states of copper oxide materials are
+discussed, and the results are qualitative consistent with the numerical
+simulations.",9708177v1
+1998-07-19,Optical Conductivity in the Copper Oxide Materials,"The frequency- and temperature-dependent optical conductivity of the copper
+oxide materials in the underdoped and optimal doped regimes are studied within
+the t-J model. The conductivity spectrum shows the unusual behavior at low
+energies and anomalous midinfrared peak in the low temperatures. However, this
+midinfrared peak is severely depressed with increasing temperatures, and
+vanishes at higher temperatures.",9807267v1
+1998-12-29,Phase Analysis of Thin Film Oxide Systems by AES and EELS,"Auger electron spectroscopy (AES) and electron energy loss spectroscopy
+(EELS) in a reflection mode are compared as the methods for phase composition
+investigation of thin film oxide systems by ion profiling. As an example, the
+Al/Al2O3/Si and YBa2Cu3O7/CeO2/Al2O3 systems are considered. The adaptation of
+applied statistics methods for AES and EELS data treatment is discussed.",9812411v1
+2002-02-10,Filling Control of the Pyrochlore Oxide Y2Ir2O7,"We report the filling control of the pyrochlore oxide Y2Ir2O7. Metallic
+ground state appears with increasing substitution content x (x >= 0.3). We have
+revealed that the density of states at the Fermi level rapidly changes with x
+by this filling control of Y2Ir2O7.",0202169v2
+2003-02-21,Evidence for Unconventional Superconductivity in the Non-Oxide Perovskite $\mathrm{MgCNi_3}$ from Penetration Depth Measurements,"The London penetration depth, $\lambda(T)$, was measured in polycrystalline
+powders of the non-oxide perovskite superconductor $\mathrm{MgCNi_3}$ by using
+a sensitive tunnel-diode resonator technique. The penetration depth exhibits
+distinctly non s-wave BCS low-temperature behavior, instead showing quadratic
+temperature dependence, suggestive of a nodal order parameter.",0302431v1
+2004-08-09,Temperature dependence of exciton Auger decay process in Cuprous Oxide,"We report theoretical and experimental study on Auger decay of excitons in
+Cuprous Oxide in a wide range of temperatures, from 2 Kelvin to 325 Kelvin, in
+single-photon surface excitation. We find that the Auger constant linearly
+increases with temperature above 100 Kelvin. This constant is important for
+experiments on Bose condensation of excitons.",0408184v2
+2004-11-25,On the Bistable Behavior of a Low-Frequency Raman-Active Phonon Line in Superconducting Oxide Ba1-xKxBiO3,"The two-loop temperature hysteresis of integrated intensity of Raman
+scattering of light is explained theoretically for a line of frequency 50 cm-1
+in a superconducting oxide Ba1-xKxBiO3 single crystal.",0411639v1
+2005-01-17,Dependence of Zinc Oxide Thin Films Properties on Filtered Vacuum Arc Deposition Parameters,"The micro-properties (structure and composition), and macro-properties
+(electrical and optical properties) of zinc oxide (ZnO) thin films deposited on
+glass substrates using a filtere vacuum arc deposition (FVAD) system were
+investigated as a function of oxygen pressure (0.37 - 0.5 Pa) and arc current
+(100 - 300 A). Correlations between the various properties were investigated.",0501374v1
+2008-04-11,"Structural and 121Sb Mössbauer Spectroscopic Investigations of the Antimonide Oxides REMnSbO (RE = La, Ce, Pr, Nd, Sm, Gd, Tb) and REZnSbO (RE = La, Ce, Pr)","The quaternary antimonide oxides REMnSbO (RE = La, Ce, Pr, Nd, Sm, Gd, Tb)
+and REZnSbO (RE = La, Ce, Pr) were synthesized from the RESb monoantimonides
+and MnO, respectively ZnO. We report on single crystal X-ray data and a
+detailed 121Sb M\""ossbauer spectroscopic investigation.",0804.1855v1
+2009-10-22,Microscopic mechanisms of spin-dependent electric polarization in 3d oxides,"We present a short critical overview of different microscopic models for
+nonrelativistic and relativistic magnetoelectric coupling including the
+so-called ""spin current scenario"", ab-initio calculations, and several recent
+microscopic approaches to a spin-dependent electric polarization in 3d oxides.",0910.4254v1
+2010-03-05,A coupled map lattice model for spontaneous pore formation in anodic oxidation,"We construct a coupled map lattice model for the spontaneous pore formation
+in anodic oxidation in two dimensions and perform numerical simulations, after
+we explain steady flat solutions, their linear stability and a single pore
+solution for a model of Parkhutik and Shershulsky.",1003.1213v1
+2010-04-25,Electron-Hole Liquids in Transition Metal Oxide Heterostructures,"Appropriately designed transition metal oxide heterostructures involving
+small band gap Mott insulators are argued to support spatially separated
+electron and hole gasses at equilibrium. Spatial separations and carrier
+densities favoring the formation of excitonic states are achievable. The
+excitonic states may exhibit potentially novel properties. Energetic estimates
+are given, candidate material systems are discussed, and the possibility of
+large photvoltaic effects is mentioned",1004.4354v1
+2010-09-02,Sensitivity of Biomarkers to Changes in Chemical Emissions in the Earth's Proterozoic Atmosphere,"The search for life beyond the Solar System is a major activity in exoplanet
+science. However, even if an Earth-like planet were to be found, it is unlikely
+to be at a similar stage of evolution as the modern Earth. It is therefore of
+interest to investigate the sensitivity of biomarker signals for life as we
+know it for an Earth-like planet but at earlier stages of evolution. Here, we
+assess biomarkers i.e. species almost exclusively associated with life, in
+present-day and in 10% present atmospheric level oxygen atmospheres
+corresponding to the Earth's Proterozoic period. We investigate the impact of
+proposed enhanced microbial emissions of the biomarker nitrous oxide, which
+photolyses to form nitrogen oxides which can destroy the biomarker ozone. A
+major result of our work is regardless of the microbial activity producing
+nitrous oxide in the early anoxic ocean, a certain minimum ozone column can be
+expected to persist in Proterozoic-type atmospheres due to a stabilising
+feedback loop between ozone, nitrous oxide and the ultraviolet radiation field.
+Atmospheric nitrous oxide columns were enhanced by a factor of 51 for the
+Proterozoic ""Canfield ocean"" scenario with 100 times increased nitrous oxide
+surface emissions. In such a scenario nitrous oxide displays prominent spectral
+features, so may be more important as a biomarker than previously considered in
+such cases. The run with ""Canfield ocean"" nitrous oxide emissions enhanced by a
+factor of 100 also featured additional surface warming of 3.5K. Our results
+suggest that the Proterozoic ozone layer mostly survives the changes in
+composition which implies that it is indeed a good atmospheric biomarker.",1009.0439v1
+2011-09-07,The effect of p-type doping on the oxidation of H-Si(111) studied by second-harmonic generation,"Atomic force microscopy and second-harmonic generation data show that boron
+doping enhances the rate of oxidation of H-terminated silicon. Holes cause a
+greater increase in the reactivity of the Si-H up bonds than that of the Si-Si
+back bonds.",1109.1486v1
+2011-09-19,Atomic layer deposition of high-k oxides on graphene,Atomic layer deposition of high-k oxides on graphene.,1109.4026v1
+2013-10-09,"Electrical, Optical and Structural Properties of Improved Transparent Conductive Oxide TCO Films","High Frequency (GW) Post Processing of Transparent Conductive Oxide, ITO,
+leads to a significant improvement of Optical Transmission and Electrical
+Conduction. This is also true in case of ITO films in multilayered structures.
+The improvements happen without any affecting the lower layers (other layers of
+the multilayered Device). This Method is extremely selective and can process
+only the targeted film (layer).",1310.2826v1
+2015-03-02,Andreev Reflection Spectroscopy in Transition Metal Oxides,"Here we review the literature concerning measurement of the Andreev
+reflection between a superconductor (S) and ferromagnet (F), with particular
+attention to the case where the ferromagnet is a transition metal oxide. We
+discuss the practicality of utilisation of the current models for determination
+of the transport current spin polarisation and examine the evidence for Andreev
+bound states.",1503.00533v1
+2015-11-23,Endurance Write Speed Tradeoffs in Nonvolatile Memories,"We derive phenomenological model for endurance-write time switching tradeoff
+for nonvolatile memories with thermally activated switching mechanisms. The
+model predicts linear to cubic dependence of endurance on write time for metal
+oxide memristors and flash memories, which is partially supported by
+experimental data for the breakdown of metal-oxide thin films.",1511.07109v1
+2009-12-13,Systematic Control of Carrier Doping without Disorder at Interface of Oxide Heterostructures,"We propose a method to systematically control carrier densities at the
+interface of transition-metal oxide heterostructures without introducing
+disorders. By inserting non-polar layers sandwiched by polar layers, continuous
+carrier doping into the interface can be realized. This method enables us to
+control the total carrier densities per unit cell systematically up to high
+values of the order unity.",0912.2484v1
+2012-05-24,Principles of crystal growth of intermetallic and oxide compounds from molten solutions,"We present a tutorial on the principles of crystal growth of intermetallic
+and oxide compounds from molten solutions, with an emphasis on the fundamental
+principles governing the underlying phase equilibria and phase diagrams of
+multicomponent systems.",1205.5592v1
+2019-11-15,Energy conversion processes with perovskite-type materials,"Mixed oxides derived from the perovskite structure by combination of A- and
+B-site elements and by partial substitution of oxygen provide an immense
+playground of physico-chemical properties. Here, we account for own research
+conducted at the Paul Scherrer Institute on perovskite-type oxides and
+oxynitrides used in electrochemical, photo(electro)chemical and catalytic
+processes aiming at facing energy relevant issues.",1911.06658v1
+2020-03-07,A Study of Selectively Digital Etching Silicon-Germanium with Nitric and Hydrofluoric Acids,"A digital etching method was proposed to achieve excellent control of etching
+depth. The digital etching characteristics of p+ Si and Si0.7Ge0.3 using the
+combinations of HNO3 oxidation and BOE oxide removal processes were studied.
+Experiments showed that oxidation saturates with time due to low activation
+energy. A physical model was presented to describe the wet oxidation process
+with nitric acid. The model was calibrated with experimental data and the
+oxidation saturation time, final oxide thickness, and selectivity between
+Si0.7Ge0.3 and p+ Si were obtained. The digital etch of laminated Si0.7Ge0.3/p+
+Si was also investigated. The depth of the tunnels formed by etching SiGe
+layers between two Si layers was found in proportion to digital etching cycles.
+And oxidation would also saturate and the saturated relative etched amount per
+cycle (REPC) was 0.5 nm (4 monolayers). A corrected selectivity calculation
+formula was presented. The oxidation model was also calibrated with
+Si0.7Ge0.3/p+ Si stacks, and selectivity from model was the same with the
+corrected formula. The model can also be used to analyze process variations and
+repeatability. And it could act as a guidance for experiment design.
+Selectivity and repeatability should make a trade-off.",2003.03529v1
+2021-03-23,"Ultrathin 2D-oxides: a perspective on fabrication, structure, defect, transport, electron and phonon properties","In the field of atomically thin 2D materials, oxides are relatively
+unexplored in spite of the large number of layered oxide structures amenable to
+exfoliation. There is an increasing interest in ultra-thin film oxide
+nanostructures from applied points of view. In this perspective paper, recent
+progress in understanding the fundamental properties of 2D oxides is discussed.
+Two families of 2D oxides are considered: (1) van der Waals bonded layered
+materials in which the transition metal is in its highest valence state
+(represented by V$_2$O$_5$ and MoO$_3$) and (2) layered materials with ionic
+bonding between positive alkali cation layers and negatively charged transition
+metal oxide layers (LiCoO$_2$). The chemical exfoliation process and its
+combinaton with mechanical exfoliation are presented for the latter. Structural
+phase stability of the resulting nanoflakes, the role of cation size and the
+importance of defects in oxides are discussed. Effects of two-dimensionality on
+phonons, electronic band structures and electronic screening are placed in the
+context of what is known on other 2D materials, such as transition metal
+dichalcogenides. Electronic structure is discussed at the level of
+many-body-perturbation theory using the quasiparticle self-consistent $GW$
+method, the accuracy of which is critically evaluated including effects of
+electron-hole interactions on screening and electron-phonon coupling. The
+predicted occurence of a two-dimensional electron gas on Li covered surfaces of
+LiCoO$_2$ and its relation to topological aspects of the band structure and
+bonding is presented as an example of the essential role of the surface in
+ultrathin materials. Finally, some case studies of the electronic transport and
+the use of these oxides in nanoscale field effect transistors are presented.",2103.12530v1
+2021-04-15,Quantum many-body effects on Rydberg excitons in cuprous oxide,"We investigate quantum many-body effects on Rydberg excitons in cuprous oxide
+induced by the surrounding electron-hole plasma. Line shifts and widths are
+calculated by full diagonalisation of the plasma Hamiltonian and compared to
+results in first order perturbation theory, and the oscillator strength of the
+exciton lines is analysed.",2104.07344v1
+2021-04-19,The effects of intrinsic local distortions vs. dynamic thermal motions on the stability and band gaps of cubic oxide and halide perovskites,"Corner-shared ABX$_3$ perovskites have long featured prominently in
+solid-state chemistry and condensed matter physics. Still, the joint
+understanding of their two main subgroups-halides and oxides-has not been fully
+developed. Indeed, unlike the case that compounds having a single repeated
+motif (""monomorphous""), certain cubic perovskites can manifest a non-thermal
+distribution of local motifs (""polymorphous networks""). Such intrinsic
+deformations can include positional degrees of freedom. Unlike thermal motion,
+such intrinsic distortions do not time-average to zero. The present study
+compares electronic structure features of oxide and halide perovskites starting
+from the intrinsic polymorphous network described by DFT minimization of the
+internal energy, continuing to finite temperature thermal disorder using AIMD.
+We find that (i) different oxide vs. halide ABX$_3$ compounds adopt different
+energy-lowering distortion modes. The DFT calculated pair distribution function
+(PDF) of SrTiO$_3$ agrees with the recently measured PDF. (ii) In both oxides
+and halides, such intrinsic distortions lead to bandgap blueshifts with respect
+to monomorphous structure. (iii) For oxide perovskites, high-temperature AIMD
+simulations initiated from the polymorphous structures reveal that the
+thermally-induced distortions can lead to a bandgap redshift. (iv) In contrast,
+for cubic CsPbI$_3$, both the intrinsic distortions and the thermal distortions
+contribute in tandem to bandgap blueshift, the former, intrinsic effect being
+dominant. (v) In the oxide SrTiO$_3$ and CaTiO$_3$ (but not in halide),
+octahedral tilting leads to the emergence of a distinct $\Gamma$-$\Gamma$
+direct bandgap component as a secondary valley minimum to the well-known
+indirect R-$\Gamma$ gap. Understanding such intrinsic vs. thermal effects on
+oxide vs. halide perovskites holds the potential for designing target
+electronic properties.",2104.09361v2
+2021-06-16,Oxidation of 2D electrenes: structural transition and the formation of half-metallic channels protected by oxide layers,"Based on first-principles calculations we performed a systematic study of the
+energetic stability, structural characterization, and electronic properties of
+the fully oxidized $A_{2}B$, electrenes, with the following combinations, (i)
+$A$=Ca, Sr, and Ba for $B$=N; (ii) $A$=Sr and Ba for $B$=P; and Y$_{2}$C, and
+Ba$_{2}$As. We have considered one side oxidation of single layer electrenes
+$(O/A_{2}B)$, and two side oxidation of bilayer electrenes
+$(O/(A_{2}B)_{2}/O)$. We show that the hexagonal lattice of the pristine host
+is no longer the ground state structure in the oxidized systems. Our total
+energy results reveal an exothermic structural transition from hexagonal to
+tetragonal (h$\rightarrow$t) geometry, resulting in layered tetragonal
+structures [$(AOAB)^{t}$, and $(AO(AB)_{2}AO)^{t}$]. Phonon spectra
+calculations and molecular dynamic simulations show that the $O/A_{2}B$, and
+$O/(A_{2}B)_{2}/O$ systems, with $A$=Ba, Ca, Sr, and $B$=N, become dynamically
+and structurally stable upon such a h$\rightarrow$t transition. Further
+structural characterizations were performed based on simulations of the near
+edge X-ray absorption spectroscopy at the nitrogen K-edge. Finally, the
+electronic structure calculations and transport calculations reveal the
+formation of half-metallic bands spreading out through the $A$N layers, which
+are shielded by oxide $A$O sheets. These findings indicate that $(AOAB)^{t}$,
+and $(AO(AB)_{2}AO)^{t}$, (with $B$=N) are quite interesting platforms for
+application in spintronics; since the half-metallic channels along the $A$N or
+$(A\text{N})_2$ layers (core) are protected against the environment conditions
+by the oxidized $A\text{O}$ sheets (cover shells).",2106.09102v5
+2022-02-11,Towards controllable Si-doping in oxide molecular beam epitaxy using a solid SiO source: Application to $β$-Ga2O3,"The oxidation-related issues in controlling Si doping from the Si source
+material in oxide molecular beam epitaxy (MBE) is addressed by using solid SiO
+as an alternative source material in a conventional effusion cell.
+Line-of-sight quadrupole mass spectrometry of the direct SiO-flux
+($\Phi_{SiO}$) from the source at different temperatures ($T_{SiO}$) confirmed
+SiO molecules to sublime with an activation energy of 3.3eV. The
+$T_{SiO}$-dependent $\Phi_{SiO}$ was measured in vacuum before and after
+subjecting the source material to an O$_{2}$-background of $10^{-5}$ mbar
+(typical oxide MBE regime). The absence of a significant $\Phi_{SiO}$
+difference indicates negligible source oxidation in molecular O$_{2}$. Mounted
+in an oxygen plasma-assisted MBE, Si-doped $\beta$-Ga2O3 layers were grown
+using this source. The $\Phi_{SiO}$ at the substrate was evaluated [from
+2.9x10$^{9}$ cm$^{-2}$s$^{-1}$ ($T_{SiO}$=700{\deg}C) to 5.5x10$^{13}$
+cm$^{-2}$s$^{-1}$ (T$_{SiO}$=1000{\deg}C)] and Si-concentration in the
+$\beta$-Ga2O3 layers measured by secondary ion mass spectrometry highlighting
+unprecedented control of continuous Si-doping for oxide MBE, i.e., $N_{Si}$
+from 4x10$^{17}$ cm$^{-3}$ ($T_{SiO}$=700{\deg}C) up to 1.7x10$^{20}$ cm$^{-3}$
+($T_{SiO}$=900{\deg}C). For a homoepitaxial $\beta$-Ga2O3 layer an Hall charge
+carrier concentration of 3x10$^{19}$ cm$^{-3}$ in line with the provided
+$\Phi_{SiO}$ ($T_{SiO}$=800{\deg}C) is demonstrated. No SiO-incorporation
+difference was found between $\beta$-Ga2O3(010) layers homoepitaxially grown at
+750{\deg}C and $\beta$-Ga2O3(-201) layers heteroepitaxially grown at
+550{\deg}C. The presence of activated oxygen (plasma) resulted in partial
+source oxidation and related decrease of doping concentration (particularly at
+$T_{SiO}$<800{\deg}C) which has been tentatively explained with a simple model.
+Degassing the source at 1100{\deg}C reverted the oxidation.",2202.05762v1
+2023-10-23,"Mass uptake during oxidation of metallic alloys: literature data collection, analysis, and FAIR sharing","The area-normalized change of mass ($\Delta$m/A) with time during the
+oxidation of metallic alloys is commonly used to assess oxidation resistance.
+Analyses of such data can also aid in evaluating underlying oxidation
+mechanisms. We performed an exhaustive literature search and digitized
+normalized mass change vs. time data for 407 alloys. To maximize the impact of
+these and future mass uptake data, we developed and published an open, online,
+computational workflow that fits the data to various models of oxidation
+kinetics, uses Bayesian statistics for model selection, and makes the raw data
+and model parameters available via a queryable database. The tool, Refractory
+Oxidation Database (https://nanohub.org/tools/refoxdb/), uses nanoHUB's Sim2Ls
+to make the workflow and data (including metadata) findable, accessible,
+interoperable, and reusable (FAIR). We find that the models selected by the
+original authors do not match the most likely one according to the Bayesian
+information criterion (BIC) in 71% of the cases. Further, in 56% of the cases,
+the published model was not even in the top 3 models according to the BIC.
+These numbers were obtained assuming an experimental noise of 2.5% of the mass
+gain range, a smaller noise leads to more discrepancies. The RefOxDB tool is
+open access and researchers can add their own raw data (those to be included in
+future publications, as well as negative results) for analysis and to share
+their work with the community. Such consistent and systematic analysis of open,
+community generated data can significantly accelerate the development of
+machine-learning models for oxidation behavior and assist in the understanding
+and improvement of oxidation resistance.",2310.15083v1
+2024-03-12,Lattice dynamics of altermagnetic ruthenium oxide RuO$_{2}$,"Altermagnetic ruthenium oxide RuO$_{2}$ crystallizes with P4$_{2}$/mnm
+symmetry. Here we discuss the lattice dynamics of this structure. We show and
+discuss the phonon dispersion and density of states. The phonon dispersion
+curves contain several Dirac nodal lines and highly degenerate Dirac points. We
+present the characteristic frequencies and their irreducible representations at
+the $\Gamma$ point. Theoretically obtained frequencies of the Raman active
+modes nicely reproduce the ones reported experimentally.",2403.07609v1
+2004-10-25,Room-temperature electric field effect and carrier-type inversion in graphene films,"The ability to control electronic properties of a material by externally
+applied voltage is at the heart of modern electronics. In many cases, it is the
+so-called electric field effect that allows one to vary the carrier
+concentration in a semiconductor device and, consequently, change an electric
+current through it. As the semiconductor industry is nearing the limits of
+performance improvements for the current technologies dominated by silicon,
+there is a constant search for new, non-traditional materials whose properties
+can be controlled by electric field. Most notable examples of such materials
+developed recently are organic conductors [1], oxides near a superconducting or
+magnetic phase transition [2] and carbon nanotubes [3-5]. Here, we describe
+another system of this kind - thin monocrystalline films of graphite - which
+exhibits a pronounced electric field effect, such that carriers in the
+conductive channel can be turned into either electrons or holes. The films
+remain metallic, continuous and of high quality down to a few atomic layers in
+thickness. The demonstrated ease of preparing such films of nearly macroscopic
+sizes and of their processing by standard microfabrication techniques, combined
+with submicron-scale ballistic transport even at room temperature, offer a new
+two-dimensional system controllable by electric-field doping and provide a
+realistic promise of device applications.",0410631v1
+2007-06-13,Electronic spin transport and spin precession in single graphene layers at room temperature,"The specific band structure of graphene, with its unique valley structure and
+Dirac neutrality point separating hole states from electron states has led to
+the observation of new electronic transport phenomena such as anomalously
+quantized Hall effects, absence of weak localization and the existence of a
+minimum conductivity. In addition to dissipative transport also supercurrent
+transport has already been observed. It has also been suggested that graphene
+might be a promising material for spintronics and related applications, such as
+the realization of spin qubits, due to the low intrinsic spin orbit
+interaction, as well as the low hyperfine interaction of the electron spins
+with the carbon nuclei. As a first step in the direction of graphene
+spintronics and spin qubits we report the observation of spin transport, as
+well as Larmor spin precession over micrometer long distances using single
+graphene layer based field effect transistors. The non-local spin valve
+geometry was used, employing four terminal contact geometries with
+ferromagnetic cobalt electrodes, which make contact to the graphene sheet
+through a thin oxide layer. We observe clear bipolar (changing from positive to
+negative sign) spin signals which reflect the magnetization direction of all 4
+electrodes, indicating that spin coherence extends underneath all 4 contacts.
+No significant changes in the spin signals occur between 4.2K, 77K and room
+temperature. From Hanle type spin precession measurements we extract a spin
+relaxation length between 1.5 and 2 micron at room temperature, only weakly
+dependent on charge density, which is varied from n~0 at the Dirac neutrality
+point to n = 3.6 10^16/m^2. The spin polarization of the ferromagnetic contacts
+is calculated from the measurements to be around 10%.",0706.1948v1
+2007-11-13,Cyclooxygenase Inhibition Limits Blood-Brain Barrier Disruption following Intracerebral Injection of Tumor Necrosis Factor-alpha in the Rat,"Increased permeability of the blood-brain barrier (BBB) is important in
+neurological disorders. Neuroinflammation is associated with increased BBB
+breakdown and brain injury. Tumor necrosis factor-a (TNF-a) is involved in BBB
+injury and edema formation through a mechanism involving matrix
+metalloproteinase (MMP) upregulation. There is emerging evidence indicating
+that cyclooxygenase (COX) inhibition limits BBB disruption following ischemic
+stroke and bacterial meningitis, but the mechanisms involved are not known. We
+used intracerebral injection of TNF-a to study the effect of COX inhibition on
+TNF-a-induced BBB breakdown, MMP expression/activity and oxidative stress. BBB
+disruption was evaluated by the uptake of 14C-sucrose into the brain and by
+magnetic resonance imaging (MRI) utilizing Gd-DTPA as a paramagnetic contrast
+agent. Using selective inhibitors of each COX isoform, we found that COX-1
+activity is more important than COX-2 in BBB opening. TNF-a induced a
+significant upregulation of gelatinase B (MMP-9), stromelysin-1 (MMP-3) and
+COX-2. In addition, TNF-a significantly depleted glutathione as compared to
+saline. Indomethacin (10 mg/kg; i.p.), an inhibitor of COX-1 and COX-2, reduced
+BBB damage at 24 h. Indomethacin significantly attenuated MMP-9 and MMP-3
+expression and activation, and prevented the loss of endogenous radical
+scavenging capacity following intracerebral injection of TNF-a. Our results
+show for the first time that BBB disruption during neuroinflammation can be
+significantly reduced by administration of COX inhibitors. Modulation of COX in
+brain injury by COX inhibitors or agents modulating prostaglandin E2
+formation/signaling may be useful in clinical settings associated with BBB
+disruption.",0711.2096v1
+2007-12-31,Evolution of the electronic excitation spectrum with strongly diminishing hole-density in superconducting Bi_{2}Sr_{2}CaCu_{2}O_{8+δ},"A complete knowledge of its excitation spectrum could greatly benefit efforts
+to understand the unusual form of superconductivity occurring in the lightly
+hole-doped copper-oxides. Here we use tunnelling spectroscopy to measure the
+T\to 0 spectrum of electronic excitations N(E) over a wide range of
+hole-density p in superconducting Bi_{2}Sr_{2}CaCu_{2}O_{8+/delta}. We
+introduce a parameterization for N(E) based upon an anisotropic energy-gap
+/Delta (\vec k)=/Delta_{1}(Cos(k_{x})-Cos(k_{y}))/2 plus an effective
+scattering rate which varies linearly with energy /Gamma_{2}(E) . We
+demonstrate that this form of N(E) allows successful fitting of differential
+tunnelling conductance spectra throughout much of the
+Bi_{2}Sr_{2}CaCu_{2}O_{8+/delta} phase diagram. The resulting average
+/Delta_{1} values rise with falling p along the familiar trajectory of
+excitations to the 'pseudogap' energy, while the key scattering rate
+/Gamma_{2}^{*}=/Gamma_{2}(E=/Delta_{1}) increases from below ~1meV to a value
+approaching 25meV as the system is underdoped from p~16% to p<10%. Thus, a
+single, particle-hole symmetric, anisotropic energy-gap, in combination with a
+strongly energy and doping dependent effective scattering rate, can describe
+the spectra without recourse to another ordered state. Nevertheless we also
+observe two distinct and diverging energy scales in the system: the energy-gap
+maximum /Delta_{1} and a lower energy scale /Delta_{0} separating the spatially
+homogeneous and heterogeneous electronic structures.",0801.0087v1
+2008-08-04,Local structures of polar wurtzites Zn_{1-x}Mg_{x}O studied by Raman and {67}Zn/{25}Mg NMR spectroscopies and by total neutron scattering,"Local compositions and structures of Zn_{1-x}Mg_{x}O alloys have been
+investigated by Raman and solid-state {67}Zn/{25}Mg nuclear magnetic resonance
+(NMR) spectroscopies, and by neutron pair-distribution-function (PDF) analyses.
+The E2(low) and E2(high) Raman modes of Zn_{1-x}Mg_{x}O display Gaussian- and
+Lorentzian-type profiles, respectively. At higher Mg substitutions, both modes
+become broader, while their peak positions shift in opposite directions. The
+evolution of Raman spectra from Zn_{1-x}Mg_{x}O solid solutions are discussed
+in terms of lattice deformation associated with the distinct coordination
+preferences of Zn and Mg. Solid-state magic-angle-spinning (MAS) NMR studies
+suggest that the local electronic environments of {67}Zn in ZnO are only weakly
+modified by the 15% substitution of Mg for Zn. {25}Mg MAS spectra of
+Zn_{0.85}Mg_{0.15}O show an unusual upfield shift, demonstrating the prominent
+shielding ability of Zn in the nearby oxidic coordination sphere. Neutron PDF
+analyses of Zn_{0.875}Mg_{0.125}O using a 2x2x1 supercell corresponding to
+Zn_{7}MgO_{8} suggest that the mean local geometry of MgO_{4} fragments concurs
+with previous density functional theory (DFT)-based structural relaxations of
+hexagonal wurtzite MgO. MgO_{4} tetrahedra are markedly compressed along their
+c-axes and are smaller in volume than ZnO_{4} units by ~6%. Mg atoms in
+Zn_{1-x}Mg_{x}O have a shorter bond to the $c$-axial oxygen atom than to the
+three lateral oxygen atoms, which is distinct from the coordination of Zn. The
+precise structure, both local and average, of Zn_{0.875}Mg_{0.125}O obtained
+from time-of-flight total neutron scattering supports the view that
+Mg-substitution in ZnO results in increased total spontaneous polarization.",0808.0492v1
+2009-01-07,Synthesis and characterization of single phase Mn doped ZnO,"Different samples of Zn1-xMnxO series have been prepared by conventional
+solid state sintering method. It has been identified, up to what extent of
+doping enable us to synthesize single-phase polycrystalline Mn doped ZnO
+samples which is one of the prerequisite for dilute magnetic semiconductor and
+we have analyzed its certain other physical aspects. In synthesizing the
+samples proportion of Mn varies from 1 at% to 5 at%. However the milling times
+have been varied (6, 12, 24, 48 & 96 hours) for only 2 at% Mn doped samples
+while for other samples (1, 3, 4 & 5 at% Mn doped) the milling time has been
+kept fixed at 96 hours. Room temperature X-Ray diffraction (XRD) data reveal
+that all of the prepared samples up to 3 at% of Mn doping exhibit wurtzite-type
+structure, no segregation of Mn and/or its oxides has been found. The 4 at% Mn
+doped samples show a weak peak of ZnMn2O4 apart from usual other peaks of ZnO
+and the intensity of this impurity peak has been further increased for 5 at% of
+Mn doping. So beyond 3 at% doping single-phase behavior is destroyed. Band gap
+for all the 2 at% Mn doped samples have been estimated as between 3.21 to 3.19
+eV and reason for this low band gap values has been explained through the grain
+boundary trapping model. The room temperature resistivity measurement shows
+increase of resistivity up to 48 hours of milling and with further milling it
+saturates. The defect state of these samples has been investigated by using
+positron annihilation lifetime (PAL) spectroscopy technique. Here all the
+relevant lifetime parameters of positron i.e. free annihilation (tau 1), at
+defect site (tau 2) and average (tau av) increases with milling time.",0901.0807v1
+2009-01-28,Extension of the spin-1/2 frustrated square lattice model: the case of layered vanadium phosphates,"We study the influence of the spin lattice distortion on the properties of
+frustrated magnetic systems and consider the applicability of the spin-1/2
+frustrated square lattice model to materials lacking tetragonal symmetry. We
+focus on the case of layered vanadium phosphates AA'VO(PO4)2 (AA' = Pb2, SrZn,
+BaZn, and BaCd). To provide a proper microscopic description of these
+compounds, we use extensive band structure calculations for real materials and
+model structures and supplement this analysis with simulations of thermodynamic
+properties, thus facilitating a direct comparison with the experimental data.
+Due to the reduced symmetry, the realistic spin model of layered vanadium
+phosphates AA'VO(PO4)2 includes four inequivalent exchange couplings: J1 and
+J1' between nearest-neighbors and J2 and J2' between next-nearest-neighbors.
+The estimates of individual exchange couplings suggest different regimes, from
+J1'/J1 and J2'/J2 close to 1 in BaCdVO(PO4)2, a nearly regular frustrated
+square lattice, to J1'/J1 ~ 0.7 and J2'/J2 ~ 0.4 in SrZnVO(PO4)2, a frustrated
+square lattice with sizable distortion. The underlying structural differences
+are analyzed, and the key factors causing the distortion of the spin lattice in
+layered vanadium compounds are discussed. We propose possible routes for
+finding new frustrated square lattice materials among complex vanadium oxides.
+Full diagonalization simulations of thermodynamic properties indicate the
+similarity of the extended model to the regular one with averaged couplings. In
+case of moderate frustration and moderate distortion, valid for all the
+AA'VO(PO4)2 compounds reported so far, the distorted spin lattice can be
+considered as a regular square lattice with the couplings (J1+J1')/2 between
+nearest-neighbors and (J2+J2')/2 between next-nearest-neighbors.",0901.4498v2
+2009-09-28,Single ion implantation for single donor devices using Geiger mode detectors,"Electronic devices that are designed to use the properties of single atoms
+such as donors or defects have become a reality with recent demonstrations of
+donor spectroscopy, single photon emission sources, and magnetic imaging using
+defect centers in diamond. Improving single ion detector sensitivity is linked
+to improving control over the straggle of the ion as well as providing more
+flexibility in lay-out integration with the active region of the single donor
+device construction zone by allowing ion sensing at potentially greater
+distances. Using a remotely located passively gated single ion Geiger mode
+avalanche diode (SIGMA) detector we have demonstrated 100% detection efficiency
+at a distance of >75 um from the center of the collecting junction. This
+detection efficiency is achieved with sensitivity to ~600 or fewer
+electron-hole pairs produced by the implanted ion. Ion detectors with this
+sensitivity and integrated with a thin dielectric, for example 5 nm gate oxide,
+using low energy Sb implantation would have an end of range straggle of <2.5
+nm. Significant reduction in false count probability is achieved by modifying
+the ion beam set-up to allow for cryogenic operation of the SIGMA detector.
+Using a detection window of 230 ns at 1 Hz, the probability of a false count
+was measured as 1E-1 and 1E-4 for operation temperatures of 300K and 77K,
+respectively. Low temperature operation and reduced false, dark, counts are
+critical to achieving high confidence in single ion arrival. For the device
+performance in this work, the confidence is calculated as a probability of >98%
+for counting one and only one ion for a false count probability of 1E-4 at an
+average ion number per gated window of 0.015.",0909.5189v1
+2010-03-13,Single-shot readout of an electron spin in silicon,"The size of silicon transistors used in microelectronic devices is shrinking
+to the level where quantum effects become important. While this presents a
+significant challenge for the further scaling of microprocessors, it provides
+the potential for radical innovations in the form of spin-based quantum
+computers and spintronic devices. An electron spin in Si can represent a
+well-isolated quantum bit with long coherence times because of the weak
+spin-orbit coupling and the possibility to eliminate nuclear spins from the
+bulk crystal. However, the control of single electrons in Si has proved
+challenging, and has so far hindered the observation and manipulation of a
+single spin. Here we report the first demonstration of single-shot,
+time-resolved readout of an electron spin in Si. This has been performed in a
+device consisting of implanted phosphorus donors coupled to a
+metal-oxide-semiconductor single-electron transistor - compatible with current
+microelectronic technology. We observed a spin lifetime approaching 1 second at
+magnetic fields below 2 T, and achieved spin readout fidelity better than 90%.
+High-fidelity single-shot spin readout in Si opens the path to the development
+of a new generation of quantum computing and spintronic devices, built using
+the most important material in the semiconductor industry.",1003.2679v3
+2010-10-21,Metal-insulator transition in Nd1-xEuxNiO3 probed by specific heat and anelastic measurements,"Oxides RNiO3 (R = rare-earth, R # La) exhibit a metal-insulator (MI)
+transition at a temperature TMI and an antiferromagnetic (AF) transition at TN.
+Specific heat (CP) and anelastic spectroscopy measurements were performed in
+samples of Nd1-xEuxNiO3, 0 <= x <= 0.35. For x = 0, a peak in CP is observed
+upon cooling and warming at essentially the same temperature TMI = TN ~ 195 K,
+although the cooling peak is much smaller. For x >= 0.25, differences between
+cooling and warming curves are negligible, and two well defined peaks are
+clearly observed: one at lower temperatures, that define TN, and the other one
+at TMI. An external magnetic field of 9 T had no significant effect on these
+results. The elastic compliance (s) and the reciprocal of the mechanical
+quality factor (Q^-1) of NdNiO3, measured upon warming, showed a very sharp
+peak at essentially the same temperature obtained from CP, and no peak is
+observed upon cooling. The elastic modulus hardens below TMI much more sharply
+upon warming, while the cooling and warming curves are reproducible above TMI.
+On the other hand, for the sample with x = 0.35, s and Q^-1 curves are very
+similar upon warming and cooling. The results presented here give credence to
+the proposition that the MI phase transition changes from first to second order
+with increasing Eu doping.",1010.4414v1
+2010-11-17,Deep Mixing in Evolved Stars: I. The Effect of Reaction Rate Revisions from C to Al,"We present computations of nucleosynthesis in low-mass red-giant-branch and
+asymptotic-giant-branch stars of Population I experiencing extended mixing. We
+adopt the updated version of the FRANEC evolutionary model, a new post-process
+code for non-convective mixing and the most recent revisions for solar
+abundances. In this framework, we discuss the effects of recent improvements in
+relevant reaction rates for proton captures on intermediate-mass nuclei (from
+carbon to aluminum). For each nucleus we briefly discuss the new choices and
+their motivations. The calculations are then performed on the basis of a
+parameterized circulation, where the effects of the new nuclear inputs are best
+compared to previous works. We find that the new rates (and notably the one for
+the 14N(p,g)15O reaction) imply considerable modifications in the composition
+of post-main sequence stars. In particular, the slight temperature changes due
+to the reduced efficiency of proton captures on 14N induce abundance variations
+at the first dredge up (especially for 17O, whose equilibrium ratio to 16O is
+very sensitive to the temperature). In this new scenario presolar oxide grains
+of AGB origin turn out to be produced almost exclusively by very-low mass stars
+(M<=1.5-1.7Msun), never becoming C-rich. The whole population of grains with
+18O/16O below 0.0015 (the limit permitted by first dredge up) is now explained.
+Also, there is now no forbidden area for very low values of 17O/16O (below
+0.0005), contrary to previous findings. A rather shallow type of transport
+seems to be sufficient for the CNO changes in RGB stages. Both thermohaline
+diffusion and magnetic-buoyancy-induced mixing might provide a suitable
+physical mechanism for this. Thermohaline mixing is in any case certainly
+inadequate to account for the production of 26Al on the AGB. Other transport
+mechanisms must therefore be at play.",1011.3948v3
+2013-05-27,Euclidian crystals in many-body systems: breakdown of Goldstone's theorem,"In accord with Nambu-Goldstone theorem spontaneous breaking of a global
+continuous symmetry of the system by a mean-field order parameter causes
+appearance of massless Goldstone bosons, called also gapless Goldstone modes.
+It is demonstrated below that the theorem can be violated, i.e. the Goldstone
+modes possess finite gap, in the case of a novel ""Euclidian crystal"" (quantum
+ordered) state of interacting fermions, that was proposed recently {mukhin
+2011}. This result may lead to the important consequences when considered in
+combination with another peculiar properties of the quantum order parameter
+(QOP) that where recently found: QOP's Green's function is finite and periodic
+along the Matsubara's axis, but Wick-rotated to the axis of real frequencies,
+possesses infinite periodic ""chain"" of \it{second order poles} along this axis
+{mukhin 2011}. This property of QOP leads to a remarkable physical consequence:
+\it{QOP does not scatter anything in Minkowski world} ! Hence, the present
+theory, we believe, may naturally indicate that two effects: ""hidden order""
+revealed in ARPES spectra of fermi-excitations and ""neutron resonance"" feature
+at finite frequency in the magnetic (bosonic) excitations spectrum in lightly
+hole-doped copper oxides, could be emerging fingerprints of the Euclidian
+crystal state. A peculiar manifestation of the QOP self-consistent solution in
+the form of non-classical phonon states is described for an ""electromagnetic
+Euclidian crystal"" predicted recently {mukhin,fistul 2013} in the array of
+Josephson junctions coupled via electromagnetic field in the superconducting
+resonator. It is demonstrated that it may constitute a stable state of the
+system, that, for a particular quantum disordering model, exists inside the
+stability domain of the classical photonic condensate delimited by the critical
+value of the quantum disordering strength.",1305.6125v2
+2014-07-22,Observation of antiferromagnetic correlations in the Hubbard model with ultracold atoms,"Ultracold atoms in optical lattices have great potential to contribute to a
+better understanding of some of the most important issues in many-body physics,
+such as high-$T_c$ superconductivity. The Hubbard model describes many of the
+features shared by the copper oxides, including an interaction-driven Mott
+insulating state and an antiferromagnetic (AFM) state. Optical lattices filled
+with a two-spin-component Fermi gas of ultracold atoms can faithfully realise
+the Hubbard model with readily tunable parameters, and thus provide a platform
+for the systematic exploration of its phase diagram. Realisation of strongly
+correlated phases, however, has been hindered by the need to cool the atoms to
+temperatures as low as the magnetic exchange energy, and also by the lack of
+reliable thermometry. Here we demonstrate spin-sensitive Bragg scattering of
+light to measure AFM spin correlations in a realisation of the 3D Hubbard model
+at temperatures down to 1.4 times that of the AFM phase transition. This
+temperature regime is beyond the range of validity of a simple high-temperature
+series expansion, which brings our experiment close to the limit of the
+capabilities of current numerical techniques. We reach these low temperatures
+using a unique compensated optical lattice technique, in which the confinement
+of each lattice beam is compensated by a blue-detuned laser beam. The
+temperature of the atoms in the lattice is deduced by comparing the light
+scattering to determinantal quantum Monte Carlo and numerical linked-cluster
+expansion calculations. Further refinement of the compensated lattice may
+produce even lower temperatures which, along with light scattering thermometry,
+would open avenues for achieving and characterising other novel quantum states
+of matter, such as the pseudogap regime of the 2D Hubbard model.",1407.5932v2
+2016-01-26,Ultrafast optical spectroscopy of strongly correlated materials and high-temperature superconductors: a non-equilibrium approach,"In the last two decades, non-equilibrium spectroscopies have evolved from
+avant-garde studies to crucial tools for expanding our understanding of the
+physics of strongly correlated materials. The possibility of obtaining
+simultaneously spectroscopic and temporal information has led to insights that
+are complementary to (and in several cases beyond) those attainable by studying
+the matter at equilibrium. Multiple phase transitions and new orders arising
+from competing interactions are benchmark examples where the interplay among
+electrons, lattice, and spin dynamics can be disentangled because of the
+different timescales that characterize the recovery of the initial ground
+state. The nature of the broken-symmetry phases and of the bosonic excitations
+that mediate the electronic interactions, eventually leading to
+superconductivity or other exotic states, can be revealed by observing the
+sub-picosecond dynamics of impulsively excited states. Recent experimental
+developments have made possible to monitor the time-evolution of both the
+single-particle and collective excitations under extreme conditions, such as
+those arising from strong and selective photo-stimulation.
+  Here, we review the most recent achievements in the experimental and
+theoretical studies of the non-equilibrium electronic, optical, structural and
+magnetic properties of correlated materials. The focus will be mainly on the
+prototypical case of correlated oxides that exhibit unconventional
+superconductivity or other exotic phases, even though the discussion will
+extend also to other topical systems. The necessity of extending the actual
+experimental capabilities and the numerical and analytic tools to
+microscopically treat the non-equilibrium phenomena beyond the simple
+phenomenological approaches represents one of the most challenging new frontier
+in physics.",1601.07204v2
+2016-09-26,Electron and phonon transport in shandite-structured Ni$_3$Sn$_2$S$_2$,"The shandite family of solids, with hexagonal structure and composition
+A3M2X2 (A = Ni,Co,Rh,Pd; M = Pb,In,Sn,Tl; X = S,Se), has attracted recent
+research attention due to promising applications as thermoelectric materials.
+Herein we discuss the electron and phonon transport properties of
+shandite-structured Ni3Sn2S2, based on a combination of density functional
+theory (DFT), Boltzmann transport theory, and experimental measurements.
+Ni3Sn2S2 exhibits a metallic and non-magnetic groundstate with Ni$^0$ oxidation
+state and very low charge on Sn and S atoms. Seebeck coefficients obtained from
+theoretical calculations are in excellent agreement with those measured
+experimentally between 100 and 600 K. From the calculation of the ratio
+$\sigma$/$\tau$ between the electronic conductivity and relaxation time, and
+the experimental determination of electron conductivity, we extract the
+variation of the scattering rate (1/$\tau$) with temperature between 300 and
+600 K, which turns out to be almost linear, thus implying that the dominant
+electron scattering mechanism in this temperature range is via phonons. The
+electronic thermal conductivity, which deviates only slightly from the
+Wiedemann-Franz law, provides the main contribution to thermal transport. The
+small lattice contribution to the thermal conductivity is calculated from the
+phonon structure and third-order force constants, and is only ~2
+Wm$^{-1}$K$^{-1}$ at 300 K (less than 10% of the total thermal conductivity),
+which is confirmed by experimental measurements. Overall, Ni$_3$Sn$_2$S$_2$ is
+a poor thermoelectric material (ZT~0.01 at 300 K), principally due to the low
+absolute value of the Seebeck coefficient. However, the understanding of its
+transport properties will be useful for the rationalization of the
+thermoelectric behavior of other, more promising members of the shandite
+family.",1609.08085v1
+2016-10-14,Three-dimensional electronic structures and the metal-insulator transition in Ruddlesden-Popper iridates,"In this study, we systematically investigate 3D momentum($\hbar k$)-resolved
+electronic structures of Ruddlesden-Popper-type iridium oxides
+Sr$_{n+1}$Ir$_n$O$_{3n+1}$ using soft-x-ray (SX) angle-resolved photoemission
+spectroscopy (ARPES). Our results provide direct evidence of an
+insulator-to-metal transition that occurs upon increasing the dimensionality of
+the IrO$_2$-plane structure. This transition occurs when the spin-orbit-coupled
+$j_{\rm eff}$=1/2 band changes its behavior in the dispersion relation and
+moves across the Fermi energy. In addition, an emerging band along the
+$\Gamma$(0,0,0)-R($\pi$,$\pi$,$\pi$) direction is found to play a crucial role
+in the metallic characteristics of SrIrO$_3$. By scanning the photon energy
+over 350 eV, we reveal the 3D Fermi surface in SrIrO$_3$ and $k_z$-dependent
+oscillations of photoelectron intensity in Sr$_3$Ir$_2$O$_7$. In contrast to
+previously reported results obtained using low-energy photons, folded bands
+derived from lattice distortions and/or magnetic ordering make significantly
+weak (but finite) contributions to the $k$-resolved photoemission spectrum. At
+the first glance, this leads to the ambiguous result that the observed
+$k$-space topology is consistent with the unfolded Brillouin zone (BZ) picture
+derived from a non-realistic simple square or cubic Ir lattice. Through careful
+analysis, we determine that a superposition of the folded and unfolded band
+structures has been observed in the ARPES spectra obtained using photons in
+both ultraviolet and SX regions. To corroborate the physics deduced using
+low-energy ARPES studies, we propose to utilize SX-ARPES as a powerful
+complementary technique, as this method surveys more than one whole BZ and
+provides a panoramic view of electronic structures.",1610.04361v1
+2018-02-25,The role of spin in the calculation of Hubbard $U$ and Hund's $J$ parameters from first principles,"The density functional theory (DFT)+$U$ method is a pragmatic and effective
+approach for calculating the ground-state properties of strongly-correlated
+systems, and linear response calculations are widely used to determine the
+requisite Hubbard parameters from first principles. We provide a detailed
+treatment of spin within this linear response approach, demonstrating that the
+conventional Hubbard $U$ formula, unlike the conventional DFT+$U$ corrective
+functional, incorporates interactions that are off-diagonal in the spin indices
+and places greater weight on one spin channel over the other. We construct
+alternative definitions for Hubbard and Hund's parameters that are consistent
+with the contemporary DFT+$U$ functional, expanding upon the minimum-tracking
+linear response method. This approach allows Hund's $J$ and spin-dependent $U$
+parameters to be calculated with the same ease as for the standard Hubbard $U$.
+Our methods accurately reproduce the experimental band gap, local magnetic
+moments, and the valence band edge character of manganese oxide, a canonical
+strongly-correlated system. We also apply our approach to a complete series of
+transition-metal complexes [M(H$_2$O)$_6$]$^{n+}$ (for M = Ti to Zn), showing
+that Hubbard corrections on oxygen atoms are necessary for preserving bond
+lengths, and demonstrating that our methods are numerically well-behaved even
+for near-filled subspaces such as in zinc. However, spectroscopic properties
+appear beyond the reach of the standard DFT+$U$ approach. Collectively, these
+results shed new light on the role of spin in the calculation of the corrective
+parameters $U$ and $J$, and point the way towards avenues for further
+development of DFT+$U$-type methods.",1802.09048v2
+2019-05-09,"Novel two-dimensional Ca-Cl crystals with metallicity, piezoelectric effect and room-temperature ferromagnetism","Recently we have reported the direct observation of two-dimensional (2D)
+Ca-Cl crystals on reduced graphene oxide (rGO) membranes, in which the calcium
+ions are only about monovalent (i.e. ~+1) and metallic rather than insulating
+properties are displayed by those CaCl crystals. Here, we report the
+experimental observation and demonstration of the formation of graphene-Ca-Cl
+heterojunction owing to the metallicity of 2D Ca-Cl crystals, unexpected
+piezoelectric effect, room-temperature ferromagnetism, as well as the distinct
+hydrogen storage and release capability of the Ca-Cl crystals in rGO membranes.
+Theoretical studies show that the formation of those abnormal crystals is
+attributed to the strong cation-pi interactions of the Ca2+ with the aromatic
+rings in the graphitic surfaces. Since strong cation-pi interactions also exist
+between other metal ions (such as Mg2+, Fe2+, Co2+, Cu2+, Cd2+, Cr2+ and Pb2+)
+and graphitic surfaces, similar 2D crystals with abnormal valence state of the
+metal cations and corresponding abnormal properties as well as novel
+applications are highly expected. Those findings further show the realistically
+potential applications of such abnormal CaCl material with unusual electronic
+properties in designing novel transistors and magnetic devices, hydrogen
+storage, catalyzer, high-performance conducting electrodes and sensors, with a
+size down to atomic scale.",1905.04135v1
+2020-07-18,Resistive AC-Coupled Silicon Detectors: principles of operation and first results from a combined analysis of beam test and laser data,"This paper presents the principles of operation of Resistive AC-Coupled
+Silicon Detectors (RSDs) and measurements of the temporal and spatial
+resolutions using a combined analysis of laser and beam test data. RSDs are a
+new type of n-in-p silicon sensor based on the Low-Gain Avalanche Diode (LGAD)
+technology, where the $n^+$ implant has been designed to be resistive, and the
+read-out is obtained via AC-coupling. The truly innovative feature of RSD is
+that the signal generated by an impinging particle is shared isotropically
+among multiple read-out pads without the need for floating electrodes or an
+external magnetic field. Careful tuning of the coupling oxide thickness and the
+$n^+$ doping profile is at the basis of the successful functioning of this
+device. Several RSD matrices with different pad width-pitch geometries have
+been extensively tested with a laser setup in the Laboratory for Innovative
+Silicon Sensors in Torino, while a smaller set of devices have been tested at
+the Fermilab Test Beam Facility with a 120 GeV/c proton beam. The measured
+spatial resolution ranges between $2.5\; \mu m$ for 70-100 pad-pitch geometry
+and $17\; \mu m$ with 200-500 matrices, a factor of 10 better than what is
+achievable in binary read-out ($bin\; size/ \sqrt{12}$). Beam test data show a
+temporal resolution of $\sim 40\; ps$ for 200-$\mu m$ pitch devices, in line
+with the best performances of LGAD sensors at the same gain.",2007.09528v4
+2016-11-16,Tunneling anomalous Hall effect in the nanogranular CoFe-B-Al-O films near the metal-insulator transition,"We present results of experimental studies of structural, magneto-transport
+and magnetic properties of CoFe-B-Al-O films deposited onto a glass ceramic
+substrate by the ion-beam sputtering of the target composed of Co40Fe40B20 and
+Al2O3 plates. The system consists on the strained crystalline CoFe metallic
+nanogranules with the size 2-5 nm which are embedded into the B-Al-O oxide
+insulating matrix. Our investigations are focused on the anomalous Hall effect
+(AHE) resistivity Rh and longitudinal resistivity R at T=5-200 K on the
+metallic side of metal-insulator transition in samples with the metal content
+x=49-56 at.%, that nominally corresponds to (Co40Fe40B20)x(Al2O3)100-x in the
+formula approximation. The conductivity at T > 15 K follows the lnT behavior
+that matches a strong tunnel coupling between nanogranules. It is shown that
+the scaling power-laws between AHE resistivity and longitudinal resistivity
+strongly differ, if temperature T or metal content x are variable parameters:
+Rh(T)~R(T)^0.4-0.5 obtained from the temperature variation of R and Rh at fixed
+x, while Rh(x)/x~R(x)^0.24, obtained from measurements at the fixed low
+temperature region (10-40 K) for samples with different x. We qualitatively
+describe our experimental data in the frame of phenomenological model of two
+sources of AHE e.m.f. arising from metallic nanogranules and insulating
+tunneling regions, respectively, at that the tunneling AHE (TAHE) source is
+strongly shunted due to generation of local circular Hall currents. We consider
+our experimental results as the first experimental proof of the TAHE
+manifestation.",1611.05195v1
+2008-07-14,Tight-binding theory of lanthanum strontium manganate,"An earlier analysis of manganese oxides in various charge states indicated
+that free-atom term values and universal coupling gave a reasonable account of
+the cohesion. This approach is here extended to LaxSr(1-x)MnO3 in a perovskite
+structure, and a wide range of properties, with comparable success, including
+the cohesion, as a function of x. Magnetic and electronic properties are
+treated in terms of the same parameters and the cluster orbitals used for
+cohesion. This includes an estimate of the Neel and Curie-Weiss temperatures
+for SrMnO3, an antiferromagnetic insulator, and the magnitude of a Jahn-Teller
+distortion in LaMnO3 which makes it also insulating with (100) ferromagnetic
+planes (due to a novel double-exchange for the distorted state),
+antiferromagnetically stacked, as observed. We estimate the Neel temperature
+and its volume dependence, and the ferromagnetic Curie-Weiss temperature which
+applies between the Neel and Jahn-Teller temperatures. We expect hopping
+conductivity when there is doping (0<x<1) and estimate it in the context of
+small-polaron theory. It is in accord with experiment between the Neel and
+Jahn-Teller temperatures, but below the Neel temperature the conduction appears
+to be band-like, for which we estimate a hole mass as enhanced in large-polaron
+theory. We see that above the Jahn-Teller temperature LaMnO3 should be metallic
+as observed, and paramagnetic with a ferromagnetic Curie-Weiss constant which
+we estimate. Many of these predictions are not so accurate, but are
+sufficiently close to provide a clear understanding of all of these properties
+in terms of a simple theory and parameters known at the outset. We provide also
+these parameters for Fe, Co, and Ca so that formulae for the properties can
+readily be evaluated for similar systems.",0807.2248v2
+2017-10-09,Pressure-induced spin pairing transition of Fe$^{3+}$ in oxygen octahedra,"High pressure can provoke spin transitions in transition metal-bearing
+compounds. These transitions are of high interest not only for fundamental
+physics and chemistry, but also may have important implications for
+geochemistry and geophysics of the Earth and planetary interiors. Here we have
+carried out a comparative study of the pressure-induced spin transition in
+compounds with trivalent iron, octahedrally coordinated by oxygen.
+High-pressure single-crystal M\""{o}ssbauer spectroscopy data for FeBO$_3$,
+Fe$_2$O$_3$ and Fe$_3$(Fe$_{1.766(2)}$Si$_{0.234(2)}$)(SiO$_4$)$_3$ are
+presented together with detailed analysis of hyperfine parameter behavior. We
+argue that $\zeta$-Fe$_2$O$_3$ is an intermediate phase in the reconstructive
+phase transition between $\iota$-Fe$_2$O$_3$ and $\theta$-Fe$_2$O$_3$ and
+question the proposed perovskite-type structure for $\zeta$-Fe$_2$O$_3$.The
+structural data show that the spin transition is closely related to the volume
+of the iron octahedron. The transition starts when volumes reach 8.9-9.3
+\AA$^3$, which corresponds to pressures of 45-60 GPa, depending on the
+compound. Based on phenomenological arguments we conclude that the spin
+transition can proceed only as a first-order phase transition in
+magnetically-ordered compounds. An empirical rule for prediction of cooperative
+behavior at the spin transition is proposed. The instability of iron octahedra,
+together with strong interactions between them in the vicinity of the critical
+volume, may trigger a phase transition in the metastable phase. We find that
+the isomer shift of high spin iron ions depends linearly on the octahedron
+volume with approximately the same coefficient, independent of the particular
+compounds and/or oxidation state. For eight-fold coordinated Fe$^{2+}$ we
+observe a significantly weaker nonlinear volume dependence.",1710.03192v1
+2017-10-14,Fingerprints of spin-orbital polarons and of their disorder in the photoemission spectra of doped Mott insulators with orbital degeneracy,"We explore the effects of disordered charged defects on the electronic
+excitations observed in the photoemission spectra of doped transition metal
+oxides in the Mott insulating regime by the example of the
+$R_{1-x}$Ca$_x$VO$_3$ perovskites, where $R=$La,$\dots$,Lu. A fundamental
+characteristic of these vanadium $d^2$ compounds with partly filled $t_{2g}$
+valence orbitals is the persistence of spin and orbital order up to high
+doping, in contrast to the loss of magnetic order in high-$T_c$ cuprates at low
+defect concentration. We demonstrate that the disordered electronic structure
+of doped Mott-Hubbard insulators can be obtained with high precision within the
+unrestricted Hartree-Fock approximation. In particular: (i) the atomic
+multiplet excitations in the inverse photoemission spectra and the various
+defect-related states and satellites are well reproduced, (ii) a robust Mott
+gap survives up to large doping, and (iii) we show that the defect states
+inside the Mott gap develop a soft gap at the Fermi energy. The soft defect
+states gap can be characterized by a shape and a scale parameter extracted from
+a Weibull statistical sampling of the density of states near the chemical
+potential. We demonstrate that charge defects trigger small spin-orbital
+polarons, with their internal kinetic energy responsible for the opening of the
+soft defect states gap. The small size of spin-orbital polarons is inferred by
+an analysis of the inverse participation ratio which explains the origin of the
+robustness of spin and orbital order. Using realistic parameters for
+La$_{1-x}$Ca$_x$VO$_3$, we show that its soft gap is well reproduced as well as
+the marginal doping dependence of the position of the chemical potential
+relative to the center of the lower Hubbard band.",1710.05171v1
+2020-12-14,Hard x-ray standing-wave photoemission study of the interfaces in a BiFeO$_3$/La$_{0.7}$Sr$_{0.3}$MnO$_3$ superlattice,"Hybrid multiferroics such as BiFeO$_3$ (BFO) and La$_{0.7}$Sr$_{0.3}$MnO$_3$
+(LSMO) heterostructures are highly interesting functional systems due to their
+complex electronic and magnetic properties. One of the key parameters
+influencing the emergent properties is the quality of interfaces, where varying
+interdiffusion lengths can give rise to different chemistry and distinctive
+electronic states. Here we report high-resolution depth resolved chemical and
+electronic investigation of BFO/LSMO superlattice using standing-wave hard
+X-ray photoemission spectroscopy in the first-order Bragg as well as
+near-total-reflection geometry. Our results show that the interfaces of BFO on
+top of LSMO are atomically abrupt, while the LSMO on top of BFO interfaces show
+an interdiffusion length of around 1.2 unit cells. The two interfaces also
+exhibit different chemical gradients, with the BFO/LSMO interface being
+Sr-terminated by a spectroscopically distinctive high binding energy component
+in Sr 2p core-level spectra, which is spatially contained within 1 unit cell
+from the interface. From the electronic point of view, unique valence band
+features were observed for bulk-BFO, bulk-LSMO and their interfaces. Our X-ray
+optical analysis revealed a unique electronic signature at the BFO/LSMO
+interface, which we attribute to the coupling between those respective layers.
+Valence band decomposition based on the Bragg-reflection standing-wave
+measurement also revealed the band alignment between BFO and LSMO layers. Our
+work demonstrates that standing-wave hard x-ray photoemission is a reliable
+non-destructive technique for probing depth-resolved electronic structure of
+buried layers and interfaces with sub-unit-cell resolution. Equivalent
+investigations can be successfully applied to a broad class of material such as
+perovskite complex oxides with emergent interfacial phenomena.",2012.07993v1
+2020-12-31,Room-temperature superconductivity in an artificial 2D Mott-insulating square lattice and its advanced condensed phase that generates a low-loss current in the atmosphere: A possible perpetual motion machine,"A 2D metallic phononic crystal (PnC), which is fabricated by drilling
+periodic holes in a suspended niobium (Nb) film, is repeatedly cooled and
+warmed in the temperature range of 2--300 K. During the first five temperature
+cycles, the resistance of the metallic PnC gradually increases in accordance
+with the Friedel sum rule, indicating that narrow Nb bridges between adjacent
+thru-holes are converted into $d$-orbital-filled Mott insulators. The
+consequent 2D Mott-insulating square lattice is a crystallographic analog of a
+copper oxide layer in high-temperature superconductors such as YBCO and BSCCO.
+Subsequent temperature cycles of the thus produced ideal Hubbard crystal
+realize zero resistance at 60 K, and the zero-resistance state remains up to
+300 K, being retained in the atmosphere (i.e., at room temperature, in a
+terrestrial magnetic field, and under atmospheric pressure). The necessity of
+the latter temperature cycles remains unclear in this study; however, a
+possible transition mechanism involving the combined Josephson and charging
+effects is discussed. The critical current and critical field of the
+room-temperature superconductor (RTSC) are $I_{C}$ = 18.8 mA and
+$\mu_{0}H_{\perp}$ = 12 T, respectively. Once a large current exceeding $I_{C}$
+is applied to the RTSC, some of the $d$ electrons are forced out, and a special
+interface consisting of the p-type semiconducting and superconducting states is
+formed. Carriers diffuse because of the nonequilibrium charge concentration,
+but they are Andreev-reflected back. In the reversible, thermally isolated
+system, the entropy never increases, and a simple experiment confirms a
+low-loss current generated from the interface spontaneously. That is, this
+study challenges the forbidden perpetual motion machine which can be a solution
+to the World energy crisis.",2012.15858v1
+2018-07-09,Evidence for Primal sp2 Defects at the Diamond Surface: Candidates for Electron Trapping and Noise Sources,"Diamond materials are central to an increasing range of advanced
+technological demonstrations, from high power electronics, to nano-scale
+quantum bio-imaging with unprecedented sensitivity. However, the full
+exploitation of diamond for these applications is often limited by the
+uncontrolled nature of the diamond material surface, which suffers from
+Fermi-level pinning and hosts a significant density of electro-magnetic noise
+sources. These issues occur despite the oxide-free and air-stable nature of the
+diamond crystal surface, which should be an ideal candidate for
+functionalization and chemical-engineering. In this work we reveal a family of
+previously unidentified and near-ubiquitous primal surface defects which we
+assign to differently reconstructed surface vacancies. The density of these
+defects is quantified with X-ray absorption spectroscopy, their energy
+structures are elucidated by ab initio calculations, and their effect on
+near-surface quantum probes is measured directly. Subsequent ab-initio
+calculation of band-bending from these defects suggest they are the source of
+Fermi-level pinning at most diamond surfaces. Finally, an investigation is
+conducted on a broad range of post-growth surface treatments and concludes that
+none of them can reproducibly reduce this defect density below the
+Fermi-pinning threshold, making this defect a prime candidate as the source for
+decoherence-limiting noise in near-surface quantum probes.",1807.02946v1
+2018-08-24,Novel electronic states realized by the interplay between Li diffusion and Co$^{\rm 3+}$$/$Co$^{\rm 4+}$ charge ordering in Li$_{\rm x}$CoO$_2$,"Measurements of dc magnetization ($M$) and electrical resistivity ($\rho$)
+have been carried out as a function of temperature ($T$) for layered oxide
+Li$_{\rm x}$CoO$_2$ (0.51$\leq$$x$$\leq$1.0) using single crystal specimens.
+After slow cool of the specimens down to 10 K, both of the $M$($T$) and
+$\rho$($T$) curves are found to exhibit a clear anomaly due to the occurrence
+of Co$^{\rm 3+}$$/$Co$^{\rm 4+}$ charge ordering (CO) at $T_{\rm S}$$\sim$155 K
+for 0.6$\leq$$x$$\leq$0.98 (at $T_{\rm S}$$\sim$180$-$190 K for
+0.5$\leq$$x$$\leq$0.55). After rapid cool of the specimens, additional
+anomalies are observed related to the onset of Li diffusion at $T_{\rm
+F1}$$\sim$370 K and$/$or $T_{\rm F2}$=120$-$130 K. Due to phase mixing with
+compositions of nearly LiCoO$_2$ and Li$_{\rm 2/3}$CoO$_2$, the specimens with
+0.7$\lesssim$$x$$\lesssim$0.9 show anomlies both at $T_{\rm F1}$ and $T_{\rm
+F2}$. For 0.6$\lesssim$$x$$\lesssim$0.9, the resistivity measured after rapid
+cool is found to be fairly larger than that measured after slow cool below
+$T_{\rm S}$. The enhanced resistivity can be explained by the scenario that
+disordered Co$^{\rm 3+}$$/$Co$^{\rm 4+}$ arrangements, which have been observed
+and revealed to have an insulating electronic structure contrasting to the
+regular CO state in the previous scanning tunneling microscopy measurements
+[Phys. Rev. Lett. {\bf 111}, 126104 (2013)], are realized due to the formation
+of an amorphous-like structure of Li ions after rapid cool via the interlayer
+Coulomb coupling. An electronic phase diagram for 0.5$\leq$$x$$\leq$1.0 is
+proposed.",1808.08010v2
+2020-06-17,Mass enhancement in 3d and s-p perovskites from symmetry breaking,"In some d-electron oxides the measured effective mass m(exptl) has long been
+known to be significantly larger than the model effective mass m(model) deduced
+from mean-field band theory, i.e., m(exptl) = beta * m(model), where beta > 1
+is the ""mass enhancement"", or ""mass renormalization"" factor. Previous
+applications of density functional theory (DFT), based on the smallest number
+of possible magnetic, orbital, and structural degrees of freedom, missed such
+mass enhancement, a fact that was taken as evidence of strong electronic
+correlation being the exclusive enabling physics. The current paper reports
+that known modalities of energy-lowering symmetry-broken spin and structural
+effects included in mean-field DFT show mass enhancement for both electrons and
+holes in a range of d-electron perovskites SrVO3, SrTiO3, BaTiO3, and LaMnO3 as
+well as p-electron perovskites CsPbI3 and SrBiO3, including metals (SrVO3) and
+insulators (the rest). This is revealed only when enlarged unit cells of the
+same parent global symmetry, which are large enough to allow for symmetry
+breaking distortions and concomitant variations in spin order, are explored for
+their ability to lower the total energy. The paper analyzes the contributions
+of different symmetry-broken modalities to mass enhancement, finds common
+effects in the range of d- as well as p-electron perovskites. Thus, symmetry
+breaking in mean-field theory could describe effects that were previously
+attributed exclusively to complex correlated treatments. Indeed, broken
+symmetries are often experimentally observed, e.g., octahedral tilting,
+Jahn-Teller distortions, or bond disproportionation, and often provide
+intuitive explanations in terms of degeneracy removal due to lowering of
+structural symmetry, or as shifting of band energies in explainable directions.",2006.10099v3
+2020-10-21,Nanoscale Dynamic Readout of a Chemical Redox Process Using Radicals Coupled with Nitrogen-Vacancy Centers in Nanodiamonds,"Biocompatible nanoscale probes for sensitive detection of paramagnetic
+species and molecules associated with their (bio)chemical transformations would
+provide a desirable tool for a better understanding of cellular redox
+processes. Here, we describe an analytical tool based on quantum sensing
+techniques. We magnetically coupled negatively charged nitrogen-vacancy (NV)
+centers in nanodiamonds (NDs) with nitroxide radicals present in a bioinert
+polymer coating of the NDs. We demonstrated that the T1 spin relaxation time of
+NV centers is very sensitive to the number of nitroxide radicals, with a
+resolution down to ~10 spins per ND (detection of approximately $ 10^-23 $ mol
+in a localized volume). The detection is based on T1 shortening upon the
+radical attachment and we propose a theoretical model describing this
+phenomenon. We further show this colloidally stable, water-soluble system can
+be used dynamically for spatiotemporal readout of a redox chemical process
+(oxidation of ascorbic acid) occurring near the ND surface in an aqueous
+environment under ambient conditions.",2010.11257v1
+2021-04-15,Two-band Conduction and Nesting Instabilities in Superconducting Ba$_2$CuO$_{3+δ}$: a First Principles Study,"First principles investigations of the high temperature superconducting
+system Ba$_2$CuO$_{3+\delta}$, recently discovered at $\delta\approx0.2$ at
+$T_c=70$ K, are applied to demonstrate the effects of oxygen ordering on the
+electronic and magnetic properties. The observed `highly over-doped'
+superconducting phase displays stretched Cu-planar oxygen O$_{\rm P}$ distances
+and anomalously shortened Cu-apical O$_{\rm A}$ separations compared with other
+cuprates. The stoichiometric system $\delta=0$, with its strongly
+one-dimensional (1D) Cu-O$_{\rm P}$ chain structure, when nonmagnetic shows 1D
+Fermi surfaces that lead, within density functional theory, to
+antiferromagnetic Cu-O$_{\rm P}$ chains (a spin-Peierls instability).
+Accounting for 1D fluctuations and small interchain coupling according to the
+theory of Schulz indicates this system, like Sr$_2$CuO$_3$, is near the 1D
+Luttinger-liquid quantum critical phase. The unusual Cu-O bond lengths per se
+have limited effects on other properties for $\delta$=0. We find that a
+`doubled bilayer' structure of alternating Cu-O$_{\rm P}$ chains and wide rung
+Cu$_3$O$_4$ ladders is the energetically preferred one of three possibilities
+where the additional oxygen ions bridge Cu-O$_{\rm P}$ chains in the
+superconducting phase $\delta=1/4$. Nominal formal valences of the three Cu
+sites are discussed. The six-fold (octahedral) site is the most highly
+oxidized, accepting somewhat more holes in the $d_{z^2}$ orbital than in the
+$d_{x^2-y^2}$ orbital. The implication is that two-band physics is involved in
+the pairing mechanism and the superconducting carriers. The Fermi surfaces of
+this metallic bilayer structure show both 1D and 2D strong (incipient) nesting
+instabilities, possibly accounting for the lack of clean single-phase samples
+based on this structure and suggesting importance for the pairing mechanism.",2104.07258v3
+2021-04-21,Electronic Structure of Mononuclear Cu-based Molecule from Density-Functional Theory with Self-Interaction Correction,"We investigate the electronic structure of a planar mononuclear Cu-based
+molecule [Cu(C$_6$H$_4$S$_2$)$_2$]$^z$ in two oxidation states ($z$$=$$-2$,
+$-$1) using density-functional theory (DFT) with Fermi-L\""owdin orbital (FLO)
+self-interaction correction (SIC). The dianionic Cu-based molecule was proposed
+to be a promising qubit candidate. Self-interaction error within approximate
+DFT functionals renders severe delocalization of electron and spin densities
+arising from 3$d$ orbitals. The FLO-SIC method relies on optimization of
+Fermi-L\""owdin orbital descriptors (FODs) with which localized occupied
+orbitals are constructed to create the SIC potentials. Starting with many
+initial sets of FODs, we employ a frozen-density loop algorithm within the
+FLO-SIC method to study the Cu-based molecule. We find that the electronic
+structure of the molecule remains unchanged despite somewhat different final
+FOD configurations. In the dianionic state (spin $S=1/2$), FLO-SIC spin density
+originates from the Cu $d$ and S $p$ orbitals with an approximate ratio of 2:1,
+in quantitative agreement with multireference calculations, while in the case
+of SIC-free DFT, the orbital ratio is reversed. Overall, FLO-SIC lowers the
+energies of the occupied orbitals and in particular the 3$d$ orbitals
+unhybridized with the ligands significantly, which substantially increases the
+energy gap between the highest occupied molecular orbital (HOMO) and the lowest
+unoccupied molecular orbital (LUMO) compared to SIC-free DFT results. The
+FLO-SIC HOMO-LUMO gap of the dianionic state is larger than that of the
+monoionic state, which is consistent with experiment. Our results suggest a
+positive outlook of the FLO-SIC method in the description of magnetic exchange
+coupling within 3$d$-element based systems.",2104.10327v1
+2022-03-02,Stacking Faults Assist Lithium-Ion Conduction in a Halide-Based Superionic Conductor,"In the pursuit of urgently-needed, energy dense solid-state batteries for
+electric vehicle and portable electronics applications, halide solid
+electrolytes offer a promising path forward with exceptional compatibility
+against high-voltage oxide electrodes, tunable ionic conductivities, and facile
+processing. For this family of compounds, synthesis protocols strongly affect
+cation site disorder and modulate Li+ mobility. In this work, we reveal the
+presence of a high concentration of stacking faults in the superionic conductor
+Li3YCl6 and demonstrate a method of controlling its Li+ conductivity by tuning
+the defect concentration with synthesis and heat treatments at select
+temperatures. Leveraging complementary insights from variable temperature
+synchrotron X-ray diffraction, neutron diffraction, cryogenic transmission
+electron microscopy, solid-state nuclear magnetic resonance, density functional
+theory, and electrochemical impedance spectroscopy, we identify the nature of
+planar defects and the role of nonstoichiometry in lowering Li+ migration
+barriers and increasing Li site connectivity in mechanochemically-synthesized
+Li3YCl6. We harness paramagnetic relaxation enhancement to enable 89Y
+solid-state NMR, and directly contrast the Y cation site disorder resulting
+from different preparation methods, demonstrating a potent tool for other
+researchers studying Y-containing compositions. With heat treatments at
+temperatures as low as 333 K (60{\deg}C), we decrease the concentration of
+planar defects, demonstrating a simple method for tuning the Li+ conductivity.
+Findings from this work are expected to be generalizable to other halide solid
+electrolyte candidates and provide an improved understanding of defect-enabled
+Li+ conduction in this class of Li-ion conductors.",2203.00814v1
+2022-03-13,Colossal transverse magnetoresistance due to nematic superconducting phase fluctuations in a copper oxide,"Electronic anisotropy (or `nematicity') has been detected in all main
+families of cuprate superconductors by a range of experimental techniques --
+electronic Raman scattering, THz dichroism, thermal conductivity, torque
+magnetometry, second-harmonic generation -- and was directly visualized by
+scanning tunneling microscope (STM) spectroscopy. Using angle-resolved
+transverse resistance (ARTR) measurements, a very sensitive and background-free
+technique that can detect 0.5$\%$ anisotropy in transport, we have observed it
+also in La$_{2-x}$Sr$_{x}$CuO$_{4}$ (LSCO) for $0.02 \leq x \leq 0.25$.
+Arguably the key enigma in LSCO is the rotation of the nematic director with
+temperature; this has not been seen before in any material. Here, we address
+this puzzle by measuring the angle-resolved transverse magnetoresistance
+(ARTMR) in LSCO. We report a discovery of colossal transverse magnetoresistance
+(CTMR) -- an order-of-magnitude drop in the transverse resistivity in the
+magnetic field of $6\,$T, while none is seen in the longitudinal resistivity.
+We show that the apparent rotation of the nematic director is caused by
+superconducting phase fluctuations, which are much more anisotropic than the
+normal-electron fluid, and their respective directors are not parallel. This
+qualitative conclusion is robust and follows straight from the raw experimental
+data. We quantify this by modelling the measured (magneto-)conductivity by a
+sum of two conducting channels that correspond to distinct anisotropic Drude
+and Cooper-pair effective mass tensors. Strikingly, the anisotropy of
+Cooper-pair stiffness is significantly larger than that of the normal
+electrons, and it grows dramatically on the underdoped side, where the
+fluctuations become effectively quasi-one dimensional.",2203.06769v1
+2022-03-16,Discovery of an electronic crystal in a cuprate Mott insulator,"Copper oxide high temperature superconductors universally exhibit multiple
+forms of electronically ordered phases that break the native translational
+symmetry of the CuO2 planes. The interplay between these orders and the
+superconducting ground state, as well as how they arise through doping a Mott
+insulator, is essential to decode the mechanisms of high-temperature
+superconductivity. Over the years, various forms of electronic liquid crystal
+phases including charge/spin stripes and incommensurate charge-density-waves
+(CDWs) were found to emerge out of a correlated metallic ground state in
+underdoped cuprates. Early theoretical studies also predicted the emergence of
+a Coulomb-frustrated 'charge crystal' phase in the very lightly-doped,
+insulating limit of the CuO2 planes. Here, we use resonant X-ray scattering,
+electron transport, and muon spin rotation measurements to fully resolve the
+electronic and magnetic ground state and search for signatures of charge order
+in very lightly hole-doped cuprates from the RBa2Cu3O7-d family (RBCO; R: Y or
+rare earth). X-ray scattering data from RBCO films reveal a breaking of
+translational symmetry more pervasive than was previously known, extending down
+to the Mott limit. The ordering vector of this charge crystal state is linearly
+connected to the charge-density-waves of underdoped RBCO, suggesting that the
+former phase is a precursor to the latter as hole doping is increased. Most
+importantly, the coexistence of charge and spin order in RBCO suggests that
+this electronic symmetry-breaking state is common to the CuO2 planes in the
+very lightly-doped regime. These findings bridge the gap between the Mott
+insulating state and the underdoped metallic state and underscore the prominent
+role of Coulomb-frustrated electronic phase separation among all cuprates.",2203.08872v1
+2022-08-10,Exoplanet weather and climate regimes with clouds and thermal ionospheres: A model grid study in support of large-scale observational campaigns,"With observational efforts moving from the discovery into the
+characterisation mode, systematic campaigns that cover large ranges of global
+stellar and planetary parameters will be needed. We aim to uncover cloud
+formation trends and globally changing chemical regimes due to the host star's
+effect on the thermodynamic structure of their atmospheres. We aim to provide
+input for exoplanet missions like JWST, PLATO, and Ariel, as well as potential
+UV missions ARAGO, PolStar or POLLUX. Pre-calculated 3D GCMs for M, K, G, F
+host stars are the input for our kinetic cloud model. Gaseous exoplanets fall
+broadly into three classes: i) cool planets with homogeneous cloud coverage,
+ii) intermediate temperature planets with asymmetric dayside cloud coverage,
+and iii) ultra-hot planets without clouds on the dayside. In class ii),} the
+dayside cloud patterns are shaped by the wind flow and irradiation. Surface
+gravity and planetary rotation have little effect. Extended atmosphere profiles
+suggest the formation of mineral haze in form of metal-oxide clusters (e.g.
+(TiO2)_N). The dayside cloud coverage is the tell-tale sign for the different
+planetary regimes and their resulting weather and climate appearance. Class (i)
+is representative of planets with a very homogeneous cloud particle size and
+material compositions across the globe (e.g., HATS-6b, NGTS-1b), classes (ii,
+e.g., WASP-43b, HD\,209458b) and (iii, e.g., WASP-121b, WP0137b) have a large
+day/night divergence of the cloud properties. The C/O ratio is, hence,
+homogeneously affected in class (i), but asymmetrically in class (ii) and
+(iii). The atmospheres of class (i) and (ii) planets are little affected by
+thermal ionisation, but class (iii) planets exhibit a deep ionosphere on the
+dayside. Magnetic coupling will therefore affect different planets differently
+and will be more efficient on the more extended, cloud-free dayside.",2208.05562v1
+2022-11-14,Antiferromagnetic metal phase in an electron-doped rare-earth nickelate,"Long viewed as passive elements, antiferromagnetic materials have emerged as
+promising candidates for spintronic devices due to their insensitivity to
+external fields and potential for high-speed switching. Recent work exploiting
+spin and orbital effects has identified ways to electrically control and probe
+the spins in metallic antiferromagnets, especially in noncollinear or
+noncentrosymmetric spin structures. The rare earth nickelate NdNiO3 is known to
+be a noncollinear antiferromagnet where the onset of antiferromagnetic ordering
+is concomitant with a transition to an insulating state. Here, we find that for
+low electron doping, the magnetic order on the nickel site is preserved while
+electronically a new metallic phase is induced. We show that this metallic
+phase has a Fermi surface that is mostly gapped by an electronic reconstruction
+driven by the bond disproportionation. Furthermore, we demonstrate the ability
+to write to and read from the spin structure via a large zero-field planar Hall
+effect. Our results expand the already rich phase diagram of the rare-earth
+nickelates and may enable spintronics applications in this family of correlated
+oxides.",2211.07525v1
+2023-01-25,Investigation of Planckian behavior in a high-conductivity oxide: PdCrO$_2$,"The layered delafossite metal PdCrO$_2$ is a natural heterostructure of
+highly conductive Pd layers Kondo coupled to localized spins in the adjacent
+Mott insulating CrO$_2$ layers. At high temperatures $T$ it has a $T$-linear
+resistivity which is not seen in the isostructural but non-magnetic PdCoO$_2$.
+The strength of the Kondo coupling is known, as-grown crystals are extremely
+high purity and the Fermi surface is both very simple and experimentally known.
+It is therefore an ideal material platform in which to investigate 'Planckian
+metal' physics. We do this by means of controlled introduction of point
+disorder, measurement of the thermal conductivity and Lorenz ratio and studying
+the sources of its high temperature entropy. The $T$-linear resistivity is seen
+to be due mainly to elastic scattering and to arise from a sum of several
+scattering mechanisms. Remarkably, this sum leads to a scattering rate within
+10$\%$ of the Planckian value of $k_BT/$$\hbar$.",2301.10631v1
+2023-04-28,Structural and Optoelectronic Properties of Thin Film LaWN$_3$,"Nitride perovskites are an emerging class of materials that have been
+predicted to display a range of interesting physics and functional properties,
+but they are under-explored due to the difficulty of synthesizing oxygen-free
+nitrides. LaWN3, recently reported as the first oxygen-free nitride perovskite,
+exhibited polar symmetry and a large piezoelectric coefficient. However, the
+predicted ferroelectric switching was hindered by large leakage current, which
+motivates better understanding of its electronic structure and optical
+properties. Here, we study the structure and optoelectronic properties of thin
+film LaWN3 in greater detail, employing combinatorial techniques to correlate
+these properties with cation stoichiometry. We report a two-step synthesis that
+utilizes a more common RF substrate bias instead of a nitrogen plasma source,
+yielding nanocrystalline films that are crystallized by ex-situ annealing. We
+investigate the structure and composition of these films, finding
+polycrystalline La-rich and highly textured W-rich films. The optical
+absorption onset and temperature- and magnetic field-dependent resistivity are
+consistent with semiconducting behavior and are highly sensitive to cation
+stoichiometry, which may be related to amorphous impurities: metallic W or WNx
+in W-rich samples and insulating La2O3 in La-rich samples. The fractional
+magnetoresistance is linear and small, consistent with defect scattering, and a
+W-rich sample has n-type carriers with high densities and low mobilities. We
+demonstrate a photoresponse in LaWN3: the resistivity of a La-rich sample is
+enhanced by 28% at low temperature, likely due to a defect trapping mechanism.
+The physical properties of LaWN3 are highly sensitive to cation stoichiometry,
+like many oxide perovskites, which therefore calls for precise composition
+control to utilize the interesting properties observed in this nitride
+perovskite.",2305.00098v1
+2023-06-13,Oxygen isotope effect on the superfluid density within the $d-$wave and $s-$wave pairing channels of YBa$_2$Cu$_4$O$_8$,"We report on measurements of the oxygen isotope ($^{16}$O/$^{18}$O) effect
+(OIE) on the transition temperature $T_{\rm c}$ and the zero-temperature
+in-plane magnetic penetration depth $\lambda_{\rm ab}(0)$ in the stoichiometric
+cuprate superconductor YBa$_2$Cu$_4$O$_8$ by means of muon-spin
+rotation/relaxation. An analysis of the temperature evolution of
+$\lambda^{-2}_{\rm ab}$ in terms of coexisting $s+d-$wave order parameters
+reveals that the OIE on the superfluid density $\rho_{\rm
+s}(0)\propto\lambda^{-2}_{\rm ab}(0)$ stems predominantly from the $d-$wave
+component while the contribution of the $s-$wave one is almost zero. The OIE on
+the transition temperature $T_{\rm c}$ is found to be rather small: $\delta
+T_{\rm c}/T_{\rm c}= -0.32(7)$%, compared to the total OIE on the superfluid
+density $\rho_{\rm s}(0)$: $\delta \rho_{\rm s}(0)/\rho_{\rm s}(0)=
+-2.8(1.0)$%. The partial OIE's on the corresponding $d-$wave and $s-$wave
+components of $\rho_{\rm s}(0)$ are $\delta \rho_{\rm s,d}(0)/\rho_{\rm s}(0)=
+-3.0(1.2)$%, and $\delta \rho_{\rm s,s}(0)/\rho_{\rm s}(0)= 0.2(1.2)$%,
+respectively. Our results demonstrate that polaron formation in the CuO$_2$
+planes is the origin of the observed OIE in the $d-$wave channel. In the much
+weaker $s-$wave channel, fermionic quasiparticles are present, which do not
+contribute to the OIE on $\rho_{\rm s}(0)$. Our results support the original
+idea of K. Alex M\""{u}ller on the polaronic nature of the supercarries in
+high-temperature cuprate superconductors.",2306.08112v1
+2023-06-27,Formation of droplets of the order parameter and superconductivity in inhomogeneous Fermi-Bose mixtures (Brief review),"The studies of a number of systems treated in terms of an inhomogeneous
+(spatially separated) Fermi-Bose mixture with superconducting clusters or
+droplets of the order parameter in a host medium with unpaired normal states
+are reviewed. A spatially separated Fermi-Bose mixture is relevant to
+superconducting BaKBiO3 bismuth oxides. Droplets of the order parameter can
+occur in thin films of a dirty metal, described in the framework of the
+strongly attractive two-dimensional Hubbard model at a low electron density
+with a clearly pronounced diagonal disorder. The Bose-Einstein condensate
+droplets are formed in mixtures and dipole gases with an imbalance in the
+densities of the Fermi and Bose components. The Bose-Einstein condensate
+clusters also arise at the center or at the periphery of a magnetic trap
+involving spin-polarized Fermi gases. Exciton and plasmon collapsing droplets
+can emerge in the presence of the exciton-exciton or plasmon-plasmon
+interaction. The plasmon contribution to the charge screening in MgB2 leads to
+the formation of spatially modulated inhomogeneous structures. In metallic
+hydrogen and metal hydrides, droplets can be formed in shock-wave experiments
+at the boundary of the first-order phase transition between the metallic and
+molecular phases. In a spatially separated Fermi-Bose mixture arising in an
+Aharonov-Bohm interference ring with a superconducting bridge in a
+topologically nontrivial state, additional Fano resonances may appear and
+collapse due to the presence of edge Majorana modes in the system.",2306.15770v1
+2023-09-09,High pressure-temperature proton migration in P-3 brucite [Mg(OH)2]: Implication for electrical conductivity in deep mantle,"Hydrous minerals contribute largely to the transport and distribution of
+water into the mantle of earth to regulate the process of deep-water cycle.
+Brucite is one of the simplest layered dense hydrous mineral belonging to
+MgO-SiO2-H2O ternary system, which contains significant amount of water in the
+form of OH- groups, spanning a wide range of pressure stability.
+Simultaneously, the pressure (p) and temperature (T) induced mobility of
+protons within the layered structure of brucite is crucial for consequences on
+electrical conductivity of the mantle. Using ab initio molecular dynamics
+(AIMD) simulations, we investigate the diffusion of H in high-pressure trigonal
+P-3 polymorph of brucite in a combined p-T range of 10-85 GPa and 1250-2000K,
+relevant to the mantle of earth. The AIMD simulations reveal an unusual
+pressure-dependence of the proton migration in brucite characterized by maximum
+H-diffusion in the pressure range of 72-76 GPa along different isotherms. We
+predict that in the P-3 brucite the H mobility is onset only when a critical
+hydrostatic pressure is attained. The onset pressure is observed to drop with
+increasing temperature. The H-diffusion in brucite phase at elevated p-T takes
+place in such a manner that the process results in the amorphization of the
+H-sublattice, without disturbing the Mg- and O-sublattices. This selective
+amorphization yields a pool of highly mobile protons causing a subsequent
+increment in the electrical conductivity in P-3 brucite. Our calculated values
+of conductivity are compared with ex-situ geophysical magnetic satellite data
+indicating that brucite can be present in larger quantities in the lower mantle
+than previously observed. This hydroxide phase can occur as segregated patches
+between the dominant constituents e.g., silicates and oxides of the lower
+mantle and thus can explain the origin of high electrical conductivity therein.",2309.04759v1
+2023-12-11,Experimental demonstration of a robust training method for strongly defective neuromorphic hardware,"The increasing scale of neural networks needed to support more complex
+applications has led to an increasing requirement for area- and
+energy-efficient hardware. One route to meeting the budget for these
+applications is to circumvent the von Neumann bottleneck by performing
+computation in or near memory. An inevitability of transferring neural networks
+onto hardware is that non-idealities such as device-to-device variations or
+poor device yield impact performance. Methods such as hardware-aware training,
+where substrate non-idealities are incorporated during network training, are
+one way to recover performance at the cost of solution generality. In this
+work, we demonstrate inference on hardware neural networks consisting of 20,000
+magnetic tunnel junction arrays integrated on a complementary
+metal-oxide-semiconductor chips that closely resembles market-ready spin
+transfer-torque magnetoresistive random access memory technology. Using 36
+dies, each containing a crossbar array with its own non-idealities, we show
+that even a small number of defects in physically mapped networks significantly
+degrades the performance of networks trained without defects and show that, at
+the cost of generality, hardware-aware training accounting for specific defects
+on each die can recover to comparable performance with ideal networks. We then
+demonstrate a robust training method that extends hardware-aware training to
+statistics-aware training, producing network weights that perform well on most
+defective dies regardless of their specific defect locations. When evaluated on
+the 36 physical dies, statistics-aware trained solutions can achieve a mean
+misclassification error on the MNIST dataset that differs from the
+software-baseline by only 2 %. This statistics-aware training method could be
+generalized to networks with many layers that are mapped to hardware suited for
+industry-ready applications.",2312.06446v1
+1998-09-02,Nonlocal electrical conductivity coefficient sigma sub-k,"A nonlocal functional is used to calculate superconducting properties of
+barium yttrium copper oxide.",9809047v1
+1999-05-07,"Pseudo-Gap Phase, the Quantum-Critical Point and superconductivity in Copper-Oxide Metals","A systematic solution of a general model for Copper-Oxides reveals a line of
+transitions $T = T_p (x)$ for $x$, the doping away from half-filling less than
+a critical value, to a phase with broken time reversal and rotational symmetry
+but with translational symmetry preserved. The single-particle spectrum in this
+phase is calculated to have a gap of $d_{x^2 - y^2}$ symmetry. The properties
+in this phase are compared to the properties of the so called ''pseudo-gap
+phase'' in the Copper-Oxides. The fluctuations towards this phase promote
+superconductivity which is either of the $d_{x^2-y^2}$ or the generalised
+s-symmetry depending on whether the projected density of states at the chemical
+potential is larger in the $d_{x^2-y^2}$ channel, as in the hole-doped
+copper-oxides, or in the s-wave channel.",9905100v1
+2000-01-19,Pseudogap effects on the c-axis charge dynamics in copper oxide materials,"The c-axis charge dynamics of copper oxide materials in the underdoped and
+optimally doped regimes has been studied by considering the incoherent
+interlayer hopping. It is shown that the c-axis charge dynamics for the chain
+copper oxide materials is mainly governed by the scattering from the in-plane
+fluctuation, and the c-axis charge dynamics for the no-chain copper oxide
+materials is dominated by the scattering from the in-plane fluctuation
+incorporating with the interlayer disorder, which would be suppressed when the
+holon pseudogap opens at low temperatures and lower doping levels, leading to
+the crossovers to the semiconducting-like range in the c-axis resistivity and
+the temperature linear to the nonlinear range in the in-plane resistivity.",0001260v1
+2001-03-14,Superconductivity in the non-oxide Perovskite MgCNi3,"The oxide perovskites are a large family of materials with many important
+physical properties. Of particular interest has been the fact that this
+structure type provides an excellent structural framework for the existence of
+superconductivity. The high Tc copper oxides are the most famous examples of
+superconducting perovskites, but there are many others [1]. Intermetallic
+compounds have been the source of many superconducting materials in the past,
+but they have been eclipsed in recent years by the perovskite oxides. The
+recent discovery of superconductivity in MgB2 [2] suggests that intermetallic
+compounds with simple structure types are worth serious reconsideration as
+sources of new superconducting materials. Here we report the observation of
+superconductivity at 8 K in the perovskite structure intermetallic compound
+MgCNi3, linking what appear at first sight to be mutually exclusive classes of
+superconducting materials. The observation of superconductivity in MgCNi3
+indicates that MgB2 will not be the only one of its kind within the chemical
+paradigm that it suggests for new superconducting materials.",0103296v1
+2001-05-29,Atomic-Scale Dynamics of the Formation and Dissolution of Carbon Clusters in SiO2,"Oxidation of SiC produces SiO2 while CO is released. A `reoxidation' step at
+lower temperatures is, however, necessary to produce high-quality SiO2. This
+step is believed to cleanse the oxide of residual C without further oxidation
+of the SiC substrate. We report first-principles calculations that describe the
+nucleation and growth of O-deficient C clusters in SiO2 under oxidation
+conditions, fed by the production of CO at the advancing interface, and their
+gradual dissolution by the supply of O under reoxidation conditions. We predict
+that both CO and CO2 are released during both steps.",0105572v1
+2001-06-13,RHEED Studies of Epitaxial Oxide Seed-Layer Growth on RABiTS Ni(001): The Role of Surface Structure and Chemistry,"The epitaxial deposition of the first oxide buffer layer (seed layer) on
+biaxially textured Ni tape for coated conductors is a critical step that is
+dependent on the atomistic surface condition of the metal. We present a study
+of the {100}<100> biaxially textured Ni (001) surface and seed-layer growth
+using in situ reflection high-energy electron diffraction (RHEED) and Auger
+electron spectroscopy (AES). Our observations are consistent with formation of
+a c(2 x 2) 2-D superstructure due to surface segregation of sulfur contained in
+the metal. We show that this superstructure can have a dramatic effect on the
+heteroepitaxial growth of oxide seed layers. In particular, the surface
+superstructure promotes the (200) epitaxial oxide growth of Y2O3-stabilized
+ZrO2 (YSZ), which is necessary for the development of high-Jc superconducting
+films for coated conductors.",0106254v1
+2001-09-26,Metastable precursors during the oxidation of the Ru(0001) surface,"Using density-functional theory, we predict that the oxidation of the
+Ru(0001) surface proceeds via the accumulation of sub-surface oxygen in
+two-dimensional islands between the first and second substrate layer. This
+leads locally to a decoupling of an O-Ru-O trilayer from the underlying metal.
+Continued oxidation results in the formation and stacking of more of these
+trilayers, which unfold into the RuO_2(110) rutile structure once a critical
+film thickness is exceeded. Along this oxidation pathway, we identify various
+metastable configurations. These are found to be rather close in energy,
+indicating a likely lively dynamics between them at elevated temperatures,
+which will affect the surface chemical and mechanical properties of the
+material.",0109491v1
+2002-04-05,Atomic-scale images of charge ordering in a mixed-valence manganite,"Transition-metal perovskite oxides exhibit a wide range of extraordinary but
+imperfectly understood phenomena. Charge, spin, orbital, and lattice degrees of
+freedom all undergo order-disorder transitions in regimes not far from where
+the best-known of these phenomena, namely high-temperature superconductivity of
+the copper oxides, and the 'colossal' magnetoresistance of the manganese
+oxides, occur. Mostly diffraction techniques, sensitive either to the spin or
+the ionic core, have been used to measure the order. Unfortunately, because
+they are only weakly sensitive to valence electrons and yield superposition of
+signals from distinct mesoscopic phases, they cannot directly image mesoscopic
+phase coexistence and charge ordering, two key features of the manganites. Here
+we describe the first experiment to image charge ordering and phase separation
+in real space with atomic-scale resolution in a transition metal oxide. Our
+scanning tunneling microscopy (STM) data show that charge order is correlated
+with structural order, as well as with whether the material is locally metallic
+or insulating, thus giving an atomic-scale basis for descriptions of the
+manganites as mixtures of electronically and structurally distinct phases.",0204146v1
+2002-06-30,"Systematic trends in the electronic structure parameters of 4d transition metal oxides SrMO_{3} (M = Zr, Mo, Ru, and Rh)","We investigated the electronic structures of the perovskite-type 4$d$
+transition metal oxides Sr$M$O$_3$ ($M$ = Zr, Mo, Ru, and Rh) using their
+optical conductivity spectra $\sigma (\omega)$. The interband transitions in
+$\sigma (\omega)$ are assigned, and some important physical parameters, such as
+on-site Coulomb repulsion energy $U$, charge transfer energy $\Delta_{pd}$, and
+crystal field splitting $10Dq$, are estimated. It is observed that $\Delta
+_{pd}$ and 10$Dq$ decrease systematically with the increase in the atomic
+number of the 4$d$ transition metal. Compared to the case of 3$d$ transition
+metal oxides, the magnitudes of $\Delta_{pd}$ and 10$Dq$ are larger, but those
+of $U$ are smaller. These behaviors can be explained by the more extended
+nature of the orbitals in the 4$d$ transition metal oxides.",0207012v1
+2002-08-26,"Sub-unit cell layer-by-layer growth of Fe3O4, MgO, and Sr2RuO4 thin films","The use of oxide materials in oxide electronics requires their controlled
+epitaxial growth. Recently, it was shown that Reflection High Energy Electron
+Diffraction (RHEED) allows to monitor the growth of oxide thin films even at
+high oxygen pressure. Here, we report the sub-unit cell molecular or block
+layer growth of the oxide materials Sr2RuO4, MgO, and magnetite using Pulsed
+Laser Deposition (PLD) from stoichiometric targets. Whereas for perovskites
+such as SrTiO3 or doped LaMnO3 a single RHEED intensity oscillation is found to
+correspond to the growth of a single unit cell, in materials where the unit
+cell is composed of several molecular layers or blocks with identical
+stoichiometry, a sub-unit cell molecular or block layer growth is established
+resulting in several RHEED intensity oscillations during the growth of a single
+unit-cell.",0208495v1
+2002-10-03,Block-Layer Concept for the Layered Co Oxide: A Design for Thermoelectric Oxides,"High-Tc Cu oxides consist of the alternating stack of the superconductive
+CuO2 layer and the block layer, such as Bi2Sr2O4 or La2-xSrxO2. By changing the
+block layer, we can change their physical properties, such as transition
+temperature Tc. The thermoelectric Co oxides have a similar layered structure
+composed of the conductive CoO2 layer and the blocking layer. Thus, we propose
+that their thremoelectric properties can be finely tuned by modifying the block
+layer.",0210071v1
+2003-01-04,Photocarrier Injection to Transition Metal Oxides,"This paper has been withdrawn by the author(s), due a crucial error in the
+data.",0301033v2
+2003-01-23,Epitaxy of Fe3O4 on Si(001) by pulsed laser deposition using a TiN/MgO buffer layer,"Epitaxy of oxide materials on silicon (Si) substrates is of great interest
+for future functional devices using the large variety of physical properties of
+the oxides as ferroelectricity, ferromagnetism, or superconductivity. Recently,
+materials with high spin polarization of the charge carriers have become
+interesting for semiconductor-oxide hybrid devices in spin electronics. Here,
+we report on pulsed laser deposition of magnetite (Fe3O4) on Si(001) substrates
+cleaned by an in situ laser beam high temperature treatment. After depositing a
+double buffer layer of titanium nitride (TiN) and magnesium oxide (MgO), a high
+quality epitaxial magnetite layer can be grown as verified by RHEED intensity
+oscillations and high resolution x-ray diffraction.",0301443v4
+2003-12-18,Dispersive charge transport along the surface of an insulating layer observed by Electrostatic Force Microscopy,"We report the observation in the direct space of the transport of a few
+thousand charges submitted to a tunable electric field along the surface of a
+silicon oxide layer. Charges are both deposited and observed using the same
+Electrostatic Force Microscope. During the time range accessible to our
+measurements (i.e. $t=1\sim1000\un{s}$), the transport of electrons is mediated
+by traps in the oxide. We measure the mobility of electrons in the ""surface""
+states of the silicon oxide layer and show the dispersive nature of their
+motion. It is also demonstrated that the saturation of deep oxide traps
+strongly enhance the transport of electrons under lateral electric field.",0312471v1
+2004-05-12,Layered tungsten oxide-based organic/inorganic hybrid materials I: Infrared and Raman study,"Tungsten oxide-organic layered hybrid materials have been studied by infrared
+and Raman spectroscopy, and demonstrate a difference in bonding nature as the
+length of the interlayer organic `spacer' molecule is increased.
+Ethylenediamine-tungsten oxide clearly displays a lack of terminal -NH3+
+ammonium groups which appear in hybrids with longer alkane molecules, thus
+indicating that the longer chains are bound by electrostatic interactions as
+well as or in place of the hydrogen bonding that must be present in the shorter
+chain ethylenediamine hybrids. The presence of organic molecules between the
+tungsten oxide layers, compared with the layered tungstic acid H2WO4, shows a
+decrease in the apical W=O bond strength, as might be expected from the
+aforementioned electrostatic interaction.",0405241v2
+2004-08-02,Ab initio study of reflectance anisotropy spectra of a sub-monolayer oxidized Si(100) surface,"The effects of oxygen adsorption on the reflectance anisotropy spectrum (RAS)
+of reconstructed Si(100):O surfaces at sub-monolayer coverage (first stages of
+oxidation) have been studied by an ab initio DFT-LDA scheme within a
+plane-wave, norm-conserving pseudopotential approach. Dangling bonds and the
+main features of the characteristic RAS of the clean Si(100) surface are mostly
+preserved after oxidation of 50% of the surface dimers, with some visible
+changes: a small red shift of the first peak, and the appearance of a distinct
+spectral structure at about 1.5 eV. The electronic transitions involved in the
+latter have been analyzed through state-by-state and layer-by-layer
+decompositions of the RAS. We suggest that new interplay between present
+theoretical results and reflectance anisotropy spectroscopy experiments could
+lead to further clarification of structural and kinetic details of the Si(100)
+oxidation process in the sub-monolayer range.",0408028v2
+2004-11-05,Multiple layer local oxidation for fabricating semiconductor nanostructures,"Coupled semiconductor nanostructures with a high degree of tunability are
+fabricated using local oxidation with a scanning force microscope. Direct
+oxidation of the GaAs surface of a Ga[Al]As heterostructure containing a
+shallow two-dimensional electron gas is combined with the local oxidation of a
+thin titanium film evaporated on top. A four-terminal quantum dot and a double
+quantum dot system with integrated charge readout are realized. The structures
+are tunable via in-plane gates formed by isolated regions in the electron gas
+and by mutually isolated regions of the Ti film acting as top gates. Coulomb
+blockade experiments demonstrate the high quality of this fabrication process.",0411129v1
+2005-01-14,Oxygen stoichiometry and instability in aluminium oxide tunnel barrier layers,"We present X-ray photoelectron spectroscopy data which show that the
+chemisorbed oxygen previously observed to be on the surface of thin AlOx layers
+formed by room temperature thermal oxidation is bound by oxygen vacancies in
+the oxide. Increasing the electric field across the oxide, either by
+over-coating with a metallic electrode, or by electron bombardment, drives this
+surface chemisorbed oxygen into the vacancy sites. Due to the low bonding
+energies of these oxygen sites, subsequent oxygen exposures draw these ions
+back to the surface, reforming chemisorbed O$_2^-$. Al/AlOx/Al tunnel junctions
+incorporating electron bombarded AlOx barriers show a significant reduction in
+the low frequency junction resistance noise level at 4.2 K.",0501354v2
+2005-01-17,Electronic structure of nanoscale iron oxide particles measured by scanning tunneling and photoelectron spectroscopies,"We have investigated the electronic structure of nano-sized iron oxide by
+scanning tunnelling microscopy (STM) and spectroscopy (STS) as well as by
+photoelectron spectroscopy. Nano particles were produced by thermal treatment
+of Ferritin molecules containing a self-assembled core of iron oxide. Depending
+on the thermal treatment we were able to prepare different phases of iron oxide
+nanoparticles resembling gamma-Fe2O3, alpha-Fe2O3, and a phase which apparently
+contains both gamma-Fe2O3 and alpha-Fe2O3. Changes to the electronic structure
+of these materials were studied under reducing conditions. We show that the
+surface band gap of the electronic excitation spectrum can differ from that of
+bulk material and is dominated by surface effects.",0501377v1
+2005-07-06,"Oxidation Resistant Germanium Nanowires: Bulk Synthesis, Long Chain Alkanethiol Functionalization and Langmuir-Blodgett Assembly","A simple method is developed to synthesize gram quantities of uniform Ge
+nanowires (GeNWs) by chemical vapor deposition on preformed, monodispersed
+seed-particles loaded onto high surface area silica support. Various chemical
+functionalization schemes are investigated to passivate the GeNW surfaces using
+alkanethiols and alkyl Grignard reactions. The stability of functionalization
+against oxidation of germanium for various alkyl chain lengths is elucidated by
+X-ray photoelectron spectroscopy. Among all schemes tested, long chain
+alkanethiols (>=C12) are found to impart the most stable GeNW passivation
+against oxidation upon extended exposure to ambient air. Further, the
+chemically functionalized oxidation-resistant nanowires are soluble in organic
+solvents and can be readily assembled into close-packed Langmuir-Blodgett films
+potentially useful for future high performance electronic devices.",0507145v2
+2005-12-08,Disorder and electron interaction control in low-doped silicon metal-oxide-semiconductor field effect transistors,"We fabricated silicon metal-oxide-semiconductor field effect transistors
+where an additional sodium-doped layer was incorporated into the oxide to
+create potential fluctuations at the Si-SiO2 interface. The amplitude of these
+fluctuations is controlled by both the density of ions in the oxide and their
+position relative to the Si-SiO2 interface. Owing to the high mobility of the
+ions at room temperature, it is possible to move them with the application of a
+suitable electric field. We show that, in this configuration, such a device can
+be used to control both the disorder and the electron-electron interaction
+strength at the Si-SiO2 interface.",0512172v3
+2005-12-28,Crystal structure of the pyrochlore oxide superconductor KOs$_2$O$_6$,"We report the single-crystal X-ray analysis of the structure of the
+pyrochlore oxide superconductor KOs$_2$O$_6$. The structure was identified as
+the $\beta$-pyrochlore structure with space group $Fd\bar{3}m$ and lattice
+constant $a$ = 10.089(2)~\AA at 300 K: the K atom is located at the 8$b$ site,
+not at the 16$d$ site as in conventional pyrochlore oxides. We found an
+anomalously large atomic displacement parameter $U_\mathrm{iso}$ =
+0.0735(8)~\AA$^2$ at 300 K for the K cation, which suggests that the K cation
+weakly bound to an oversized Os$_{12}$O$_{18}$ cage exhibits intensive
+rattling, as recently observed for clathrate compounds. The rattling of A
+cations is a common feature in the series of $\beta$-pyrochlore oxide
+superconductors AOs$_2$O$_6$ (A = Cs, Rb and K), and is greatest for the
+smallest K cation.",0512683v1
+2006-02-22,An Improved Description of the Dielectric Breakdown in Oxides Based on a Generalized Weibull distribution,"In this work, we address modal parameter fluctuations in statistical
+distributions describing charge-to-breakdown $(Q_{BD})$ and/or
+time-to-breakdown $(t_{BD})$ during the dielectric breakdown regime of
+ultra-thin oxides, which are of high interest for the advancement of electronic
+technology. We reobtain a generalized Weibull distribution ($q$-Weibull), which
+properly describes $(t_{BD})$ data when oxide thickness fluctuations are
+present, in order to improve reliability assessment of ultra-thin oxides by
+time-to-breakdown $(t_{BD})$ extrapolation and area scaling. The incorporation
+of fluctuations allows a physical interpretation of the $q$-Weibull
+distribution in connection with the Tsallis statistics. In support to our
+results, we analyze $t_{BD}$ data of SiO$_2$-based MOS devices obtained
+experimentally and theoretically through a percolation model, demonstrating an
+advantageous description of the dielectric breakdown by the $q$-Weibull
+distribution.",0602515v1
+2006-04-03,Electrical conduction of silicon oxide containing silicon quantum dots,"Current-voltage measurements have been made at room temperature on a Si-rich
+silicon oxide film deposited via Electron-Cyclotron Resonance Plasma Enhanced
+Chemical Vapor Deposition (ECR-PECVD) and annealed at 750 - 1000$ ^\circ$C. The
+thickness of oxide between Si quantum dots embedded in the film increases with
+the increase of annealing temperature. This leads to the decrease of current
+density as the annealing temperature is increased. Assuming the Fowler-Nordheim
+tunneling mechanism in large electric fields, we obtain an effective barrier
+height $\phi_{eff}$ of $\sim$ 0.7 $\pm$ 0.1 eV for an electron tunnelling
+through an oxide layer between Si quantum dots. The Frenkel-Poole effect can
+also be used to adequately explain the electrical conduction of the film under
+the influence of large electric fields. We suggest that at room temperature Si
+quantum dots can be regarded as traps that capture and emit electrons by means
+of tunneling.",0604028v1
+2007-05-05,Theory of enhanced dynamical photo-thermal bi-stability effects in cuprous oxide/organic hybrid heterostructure,"We theoretically demonstrate the formation of multiple bi-stability regions
+in the temperature pattern on the interface between a cuprous oxide quantum
+well and DCM2:CA:PS organic compound. The Frenkel molecular exciton of the DCM2
+is brought into resonance with the $1S$ quadrupole Wannier-Mott exciton in the
+cuprous oxide by ""solvatochromism"" with CA. The resulting hybrid is thermalized
+with surrounding helium bath. This leads to strongly non-linear temperature
+dependence of the laser field detuning from the quadrupole exciton energy band
+which is associated with the temperature induced red shift of the Wannier
+exciton energy. Numerical up and down-scan for the detuning reveals
+hysteresis-like temperature distribution. The obtained \emph{multiple}
+bi-stability regions are at least three orders of magnitude bigger ($meV$) than
+the experimentally observed bi-stability in bulk cuprous oxide ($\mu eV$). The
+effective absorption curve exhibits highly asymmetrical behavior for the
+Frenkel-like (above the $1S$ energy) and Wannier-like (below the $1S$ energy)
+branches of the hybrid.",0705.0731v1
+2007-08-14,"Theory of oxidation/reduction-induced chromium ion valence transformations in Cr,Ca:YAG crystals","In their paper [Opt. Mater. 24, 333, 2003], Feldman et al conducted an
+experimental study of the dynamics of chromium ion valence transformations in
+Cr,Ca:YAG crystals among the trivalent Cr3+ state, and two tetravalent Cr4+
+ones, of octahedral and tetrahedral coordination. The temperatures used ranged
+between ~800 and 1,000 C. The basic effects are the transition of Cr3+ into
+Cr4+ under high-temperature annealing in an oxidizing atmosphere, and the
+reverse transition under a reducing atmosphere, or in vacuum. In the present
+theory, we interpret the processes by oxygen-vacancy diffusion in the bulk of
+the YAG. The quasi-chemical reaction VO2- + Cr4+ = Cr3+/VO- between the
+chromium ions and the vacancies VO2- is responsible for the valence
+transformations. Dynamical analysis provides profiles of the Cr3+ and Cr4+
+concentrations in the crystal during oxidation and during reduction. Reaction
+rate profiles are also calculated, establishing the reaction front position and
+width. A comparison with existing experimental results on the integrated Cr4+
+concentration as a function of time during oxidation [Opt. Mater. 24, 333,
+2003] shows reasonable agreement.",0708.1798v2
+2007-10-02,Microscopic mechanisms of spin-dependent electric polarization in 3d oxides,"We address a systematic microscopic theory of spin-dependent electric
+polarization in 3d oxides starting with a generic three-site two-hole cluster.
+A perturbation scheme realistic for 3d oxides is applied which implies the
+quenching of orbital moments by low-symmetry crystal field, strong intra-atomic
+correlations, the dp-transfer effects, and rather small spin-orbital coupling.
+An effective spin operator of the electric dipole moment is deduced
+incorporating both nonrelativistic and relativistic terms. The nonrelativistic
+electronic polarization mechanism related with the effects of the
+redistribution of the local on-site charge density due to $pd$ covalency and
+exchange coupling is believed to govern the multiferroic behaviour in 3d
+oxides. The relativistic exchange-dipole moment is mainly stems from the
+nonrelativistic one due to the perturbation effect of Dzyaloshinsky-Moriya
+coupling and is estimated to be a weak contributor to the electric polarization
+observed in the most of 3d multiferroics.",0710.0496v1
+2007-10-05,Self-consistent simulation of quantum wires defined by local oxidation of Ga[Al]As heterostructures,"We calculate the electronic width of quantum wires as a function of their
+lithographic width in analogy to experiments performed on nanostructures
+defined by local oxidation of Ga[Al]As heterostructures. Two--dimensional
+simulations of two parallel oxide lines on top of a Ga[Al]As heterostructure
+defining a quantum wire are carried out in the framework of Density Functional
+Theory in the Local Density Approximation and are found to be in agreement with
+measurements. Quantitative assessment of the influence of various experimental
+uncertainties is given. The most influential parameter turns out to be the
+oxide line depth, followed by its exact shape and the effect of background
+doping (in decreasing order).",0710.1160v2
+2007-10-30,"Conformational and Structural Relaxations of Poly(ethylene oxide) and Poly(propylene oxide) Melts: Molecular Dynamics Study of Spatial Heterogeneity, Cooperativity, and Correlated Forward-Backward Motion","Performing molecular dynamics simulations for all-atom models, we
+characterize the conformational and structural relaxations of poly(ethylene
+oxide) and poly(propylene oxide) melts. The temperature dependence of these
+relaxation processes deviates from an Arrhenius law for both polymers. We
+demonstrate that mode-coupling theory captures some aspects of the glassy
+slowdown, but it does not enable a complete explanation of the dynamical
+behavior. When the temperature is decreased, spatially heterogeneous and
+cooperative translational dynamics are found to become more important for the
+structural relaxation. Moreover, the transitions between the conformational
+states cease to obey Poisson statistics. In particular, we show that, at
+sufficiently low temperatures, correlated forward-backward motion is an
+important aspect of the conformational relaxation, leading to strongly
+nonexponential distributions for the waiting times of the dihedrals in the
+various conformational states",0710.5598v1
+2008-04-23,The role of metallic impurities in oxide semiconductors: first-principles calculations and PAC experiments,"We report an ab-initio comparative study of the electric-field-gradient
+tensor (EFG) and structural relaxations introduced by acceptor (Cd) and donor
+(Ta) impurities when they replace cations in a series of binary oxides: TiO2,
+SnO2, and In2O3. Calculations were performed with the Full-Potential
+Linearized-Augmented Plane Waves method that allows us to treat the electronic
+structure and the atomic relaxations in a fully self-consistent way. We
+considered different charge states for each impurity and studied the dependence
+on these charge states of the electronic properties and the structural
+relaxations. Our results are compared with available data coming from PAC
+experiments and previous calculations, allowing us to obtain a new insight on
+the role that metal impurities play in oxide semiconductors. It is clear from
+our results that simple models can not describe the measured EFGs at impurities
+in oxides even approximately.",0804.3644v1
+2008-06-08,Novel electronic structure induced by a highly strained oxide interface with incommensurate crystal fields,"The misfit oxide, Bi$_{2}$Ba$_{1.3}$K$_{0.6}$Co$_{2.1}$O$_{y}$, made of
+alternating rocksalt-structured [BiO/BaO] layers and hexagonal CoO$_{2}$
+layers, was studied by angle-resolved photoemission spectroscopy. Detailed
+electronic structure of such a highly strained oxide interfaces is revealed for
+the first time. We found that under the two incommensurate crystal fields,
+electrons are confined within individual sides of the interface, and scattered
+by umklapp scattering of the crystal field from the other side. In addition,
+the high strain on the rocksalt layer raises its chemical potential and induces
+large charge transfer to the CoO$_{2}$ layer. Furthermore, a novel interface
+effects, the interfacial enhancement of electron-phonon interactions, is
+discovered. Our findings of these electronic properties lay a foundation for
+designing future functional oxide interfaces.",0806.1338v1
+2008-09-16,Microscopic Bardeen-Cooper-Schrieffer formulation of the critical temperature of multilayer copper-oxide superconductors,"We study superconductivity in multilayer copper oxides, in the frame of a
+realistic microscopic formulation. Solving the full temperature dependent BCS
+gap equations, we obtain a maximum in the transition temperature Tc for M=3 or
+4 CuO2 layers in the unit cell for appropriate values of the interlayer
+tunneling (negative pair tunneling), and via the consideration of the doping
+imbalance between the inner and outer layers. This is the ubiquitous
+experimental result for Ca intercalated copper oxides, as opposed to other
+intercalating elements. Further, using a restricted set of parameters, we
+obtain an exact fit of Tc(M=1-4) for five different Ca intercalated homologuous
+copper oxide families.",0809.2656v5
+2008-09-29,Charge state of the O$_{2}$ molecule during silicon oxidation through hybrid functional calculations,"We study the charge state of the diffusing O$_2$ molecule during silicon
+oxidation through hybrid functional calculations. We calculate charge
+transition levels of O$_2$ in bulk SiO$_2$ and use theoretical band offsets to
+align these levels with respect to the Si band edges. To overcome the band-gap
+problem of semilocal density fuctionals, we employ hybrid functionals with both
+predefined and empirically adjusted mixing coefficients. We find that the
+charge transition level $\epsilon^{0/-}$ in bulk SiO$_2$ occurs at $\sim$1.1 eV
+above the silicon conduction band edge, implying that the O$_2$ molecule
+diffuses through the oxide in the neutral charge state. While interfacial
+effects concur to lower the charge transition level, our estimates suggest that
+the neutral charge state persists until silicon oxidation.",0809.4905v1
+2008-11-28,Mixed valency in cerium oxide crystallographic phases: Determination of valence of the different cerium sites by the bond valence method,"We have applied the bond valence method to cerium oxides to determine the
+oxidation states of the Ce ion at the various site symmetries of the crystals.
+The crystals studied include cerium dioxide and the two sesquioxides along with
+some selected intermediate phases which are crystallographically well
+characterized. Our results indicate that cerium dioxide has a mixed-valence
+ground state with an f-electron population on the Ce site of 0.27 while both
+the A- and C-sesquioxides have a nearly pure f^1 configuration. The Ce sites in
+most of the intermediate oxides have non-integral valences. Furthermore, many
+of these valences are different from the values predicted from a naive
+consideration of the stoichiometric valence of the compound.",0811.4634v1
+2009-03-16,Polarization properties of real aluminum mirrors; I. Influence of the aluminum oxide layer,"In polarimetry it is important to characterize the polarization properties of
+the instrument itself to disentangle real astrophysical signals from
+instrumental effects. This article deals with the accurate measurement and
+modeling of the polarization properties of real aluminum mirrors, as used in
+astronomical telescopes. Main goals are the characterization of the aluminum
+oxide layer thickness at different times after evaporation and its influence on
+the polarization properties of the mirror. The full polarization properties of
+an aluminum mirror are measured with Mueller matrix ellipsometry at different
+incidence angles and wavelengths. The best fit of theoretical Mueller matrices
+to all measurements simultaneously is obtained by taking into account a model
+of bulk aluminum with a thin aluminum oxide film on top of it. Full Mueller
+matrix measurements of a mirror are obtained with an absolute accuracy of ~1%
+after calibration. The determined layer thicknesses indicate logarithmic growth
+in the first few hours after evaporation, but it remains stable at a value of
+4.12+/-0.08 nm on the long term. Although the aluminum oxide layer is
+established to be thin, it is necessary to consider it to accurately describe
+the mirror's polarization properties.",0903.2740v1
+2009-03-22,Influence of EGR compounds on the oxidation of an HCCI-diesel surrogate,"This paper presents an experimental and numerical study of the impact of
+various additives on the oxidation of a typical automotive surrogate fuel
+blend, i.e. n-heptane and toluene. It examines the impact of engine re-cycled
+exhaust has compounds on the control of an Homogeneous Charge
+Compression-Ignition (HCCI) engine. Series of experiments were performed in a
+hihly diluted Jet-Stirred Reactor (JDR) at pressures of 1 and 10 atm (1 atm =
+101,325 Pa). The chosen thermo-chemical conditions were close to those
+characteristices of the pre-ignition period in an HCCI engine. The influence of
+various additives, namely nitric oxide (NO), ethylene (C2H4) and methanol
+(CH3OH), on the oxidation of a n-heptane/toluene blend was studied over a wide
+range of temperatures (550-1100 K), including the zone of the Negative
+Temperature Coefficient (NTC).",0903.3707v1
+2009-04-23,Characterization of a novel angular dioxygenase from fluorene-degrading Sphingomonas sp. strain LB126,"In this study, the genes involved in the initial attack on fluorene by
+Sphingomonas sp. LB126 were investigated. The ? and ? subunits of a dioxygenase
+complex (FlnA1A2), showing 63% and 51% sequence identity respectively, with the
+subunits of an angular dioxygenase from Gram-positive Terrabacter sp. DBF63,
+were identified. When overexpressed in E. coli, FlnA1A2 was responsible for the
+angular oxidation of fluorene, fluorenol, fluorenone, dibenzofuran and
+dibenzo-p-dioxin. Moreover, FlnA1A2 was able to oxidize polycyclic aromatic
+hydrocarbons and heteroaromatics, some of which were not oxidized by the
+dioxygenase from Terrabacter sp. DBF63. Quantification of resulting oxidation
+products showed that fluorene and phenanthrene were preferred substrates.",0904.3654v1
+2009-05-27,Coulomb explosion sputtering of selectively oxidized Si,"We have studied multiply charged Arq+ ion induced potential sputtering of a
+unique system comprising of coexisting Silicon and Silicon oxide surfaces. Such
+surfaces are produced by oblique angle oxygen ion bombardment on Si(100), where
+ripple structures are formed and one side of each ripple gets more oxidized. It
+is observed that higher the potential energy of Arq+ ion, higher the sputtering
+yield of the non conducting (oxide) side of the ripple as compared to the
+semiconducting side. The results are explained in terms of Coulomb explosion
+model where potential sputtering depends on the conductivity of the ion impact
+sites.",0905.4343v2
+2009-09-14,A thermodynamic approach of the mechano-chemical coupling during the oxidation of uranium dioxide,"The aim of the present work is to introduce a thermodynamic model to describe
+the growth of an oxide layer on a metallic substrate. More precisely, this
+paper offers a study of oxygen dissolution into a solid, and its consequences
+on the apparition of mechanical stresses. They strongly influence the oxidation
+processes and may be, in some materials, responsible for cracking. To realize
+this study, mechanical considerations are introduced into the classical
+diffusion laws. Simulations were made for the particular case of uranium
+dioxide, which undergoes the chemical fragmentation. According to our
+simulations, the hypothesis of a compression stress field into the oxidised UO2
+compound near the internal interface is consistent with the interpretation of
+the mechanisms of oxidation observed experimentally.",0909.2605v1
+2009-09-16,"Theoretical Study of Coupling Mechanisms between Oxygen Diffusion, Chemical Reaction, Mechanical Stresses in a Solid-Gas Reactive System","This paper offers a study of oxygen dissolution into a solid, and its
+consequences on the mechanical behaviour of the material. In fact, mechanical
+strains strongly influence the oxidation processes and may be, in some
+materials, responsible for cracking. To realize this study, mechanical
+considerations are introduced into the classical diffusion laws. Simulations
+were made for the particular case of uranium dioxide, which undergoes the
+chemical fragmentation. According to our simulations, the hypothesis of a
+compression stress field into the oxidised UO2 compound near the internal
+interface is consistent with some oxidation mechanisms of oxidation
+experimentally observed. More generally, this work will be extended to the
+simulation to an oxide layer growth on a metallic substrate.",0909.2950v1
+2010-02-05,Quantifying octahedral rotations in strained perovskite oxide films,"Epitaxial strain is a proven route to enhancing the properties of complex
+oxides, however, the details of how the atomic structure accommodates strain
+are poorly understood due to the difficulty of measuring the oxygen positions
+in thin films. We present a general methodology for determining the atomic
+structure of strained oxide films via x-ray diffraction, which we demonstrate
+using LaNiO3 films. The oxygen octahedral rotations and distortions have been
+quantified by comparing the intensities of half-order Bragg peaks, arising from
+the two unit cell periodicity of the octahedral rotations, with the calculated
+structure factor. Combining ab initio density functional calculations with
+these experimental results, we determine systematically how strain modifies the
+atomic structure of this functional oxide.",1002.1317v1
+2010-02-12,Experimental Study of Resistive Bistability in Metal Oxide Junctions,"We have studied resistive bistability (memory) effects in junctions based on
+metal oxides, with a focus on sample-to-sample reproducibility which is
+necessary for the use of such junctions as crosspoint devices of hybrid
+CMOS/nanoelectronic circuits. Few-nm-thick layers of NbOx, CuOx and TiOx have
+been formed by thermal and plasma oxidation, at various deposition and
+oxidation conditions, both with or without rapid thermal post-annealing (RTA).
+The resistive bistability effect has been observed for all these materials,
+with particularly high endurance (over 1000 switching cycles) obtained for
+single-layer TiO2 junctions, and the best reproducibility reached for
+multi-layer junctions of the same material. Fabrication optimization has
+allowed us to improve the OFF/ON resistance ratio to about 1000, but the
+sample-to-sample reproducibility is so far lower than that required for large
+scale integration.",1002.2650v1
+2010-02-26,Measuring individual overpotentials in an operating solid-oxide electrochemical cell,"We use photo-electrons as a non-contact probe to measure local electrical
+potentials in a solid-oxide electrochemical cell. We characterize the cell in
+operando at near-ambient pressure using spatially-resolved X-ray photoemission
+spectroscopy. The overpotentials at the interfaces between the Ni and Pt
+electrodes and the yttria-stabilized zirconia (YSZ) electrolyte are directly
+measured. The method is validated using electrochemical impedance spectroscopy.
+Using the overpotentials, which characterize the cell's inefficiencies, we
+compare without ambiguity the electro-catalytic efficiencies of Ni and Pt,
+finding that on Ni H_2O splitting proceeds more rapidly than H2 oxidation,
+while on Pt, H2 oxidation proceeds more rapidly than H2O splitting.",1003.0035v2
+2010-04-23,Synthesis of novel Mesoporous Fullerene and its application to electro-oxidation of methanol,"One pot synthetic technique was used to synthesize mesoporous fullerene using
+highly ordered mesoporous template such as KIT6-150 and SBA-15-150. Highly
+ordered porous fullerene with cross linkage between the fullerene molecules was
+obtained at high temperature 900 0C. This type of highly ordered and high
+surface area mesoporous fullerence was used as catalyst to study anodic
+performance in sulphuric acid medium. Finally, it was used to test its
+catalytic activity for electrochemical methanol oxidation. For anodic
+performance and methanol oxidation experiment, mesofullerene was impregnated
+with pt-nano particles. Mesoporous Fullerene-Pt nano-composite showed quite an
+unusual electrochemical property for electro oxidation of methanol and good
+anodic performance in acidic electrolyte. The anodic performance was much
+better than the commercially available carbon black. This short communiation is
+a report mentioning the synthetic strategy to prepare mesofullerene and
+electrode preparation to study its electrochemical performance. This
+mesofullerene is potential catalyst for fuel cell application.",1004.4046v4
+2010-04-26,"Chemical control of orbital polarization in artificially structured transition-metal oxides: La2NiXO6 (X=B, Al, Ga, In) from first principles","The application of modern layer-by-layer growth techniques to
+transition-metal oxide materials raises the possibility of creating new classes
+of materials with rationally designed correlated electron properties. An
+important step toward this goal is the demonstration that electronic structure
+can be controlled by atomic composition. In compounds with partially occupied
+transition-metal d shells, one important aspect of the electronic structure is
+the relative occupancy of different d orbitals. Previous work has established
+that strain and quantum confinement can be used to influence orbital occupancy.
+In this paper we demonstrate a different modality for orbital control in
+transition-metal oxide heterostructures, using density-functional band
+calculations supplemented by a tight-binding analysis to show that the choice
+of nontransition-metal counterion X in transition-metal oxide heterostructures
+composed of alternating LaNiO3 and LaXO3 units strongly affects orbital
+occupancy, changing the magnitude and in some cases the sign of the orbital
+polarization.",1004.4678v2
+2010-06-07,Evidence Of Protein Collective Motions On The Picosecond Time Scale,"We investigate the presence of structural collective motions on a picosecond
+time scale for the heme protein, cytochrome c, as a function of oxidation and
+hydration, using terahertz (THz) time-domain spectroscopy and molecular
+dynamics simulations. The THz response dramatically increases with oxidation,
+with the largest increase for lowest hydrations and highest frequencies. For
+both oxidation states the THz response rapidly increases with hydration
+saturating above ~25% (g H2O/g protein). Quasi-harmonic vibrational modes and
+dipole-dipole correlation functions are calculated from molecular dynamics
+trajectories. The collective mode density of states alone reproduces the
+measured hydration dependence providing strong evidence of the existence of
+these motions. The large oxidation dependence is reproduced only by the
+dipole-dipole correlation function, indicating the contrast arises from
+diffusive motions consistent with structural changes occurring in the vicinity
+of a buried internal water molecule.",1006.1314v1
+2010-06-15,Quantum Dielectric Fluctuation in an Electronic Ferroelectricity studied by Variational Monte-Carlo Method,"Electronic structure and dielectric property in an electronic
+ferroelectricty, where electric polarization is driven by an electronic charge
+order without inversion symmetry, are studied. Motivated from layered iron
+oxides, roles of quantum fluctuation on ferroelectricity in a paired-triangular
+lattice are focused on. Three types of the extended V-t model are examined by
+the variational Monte-Carlo method with the Gutzwiller-type correlation factor.
+It is shown that electron transfer between the triangular layers corresponding
+to the inter-layer polarization fluctuation promotes the three-fold charge
+order associated with an electric polarization. This result is in highly
+contrast to the usual manner of quantum fluctuation in the hydrogen-bond type
+ferroelectricities and the quantum paraelectric oxides. Spin degree of freedom
+of electron and a realistic crystal structure for the layered iron oxides
+further stabilize the polar charge ordered state. Implications of the numerical
+results for layered iron oxides are discussed.",1006.2889v1
+2010-08-18,A Stepped Oxide Hetero-Material Gate Trench Power MOSFET for Improved Performance,"In this work, we propose a new Stepped Oxide Hetero-Material Trench (SOHMT)
+power MOSFET with three sections in the trench gate (an N+ poly gate sandwiched
+between two P+ poly gates) and having different gate oxide thicknesses
+(increasing from source side to drain side). The different gate oxide thickness
+serves the purpose of simultaneously achieving (i) a good gate control on the
+channel charge and (ii) a lesser gate to drain capacitance. As a result, we
+obtain higher transconductance as well as reduced switching delays, making the
+proposed device suitable for both RF amplification and high speed switching
+applications. In addition, the sandwiched gate with different work function
+gate materials modifies the electric field profile in the channel resulting in
+an improved breakdown voltage. Using two-dimensional simulations, we have shown
+that the proposed device structure exhibits about 32% enhancement in breakdown
+voltage, 25% reduction in switching delays, 20% enhancement in peak
+transconductance and 10% reduction in figure of merit (product of ON-resistance
+and gate charge) as compared to the conventional trench gate MOSFET.",1008.3022v1
+2010-11-29,"Contact effects on transport in magnetite, an archetypal correlated transition metal oxide","Multiterminal measurements have typically been employed to examine electronic
+properties of strongly correlated electronic materials such as transition metal
+oxides without the influence of contact effects. In contrast, in this work we
+investigate the interface properties of Fe$_3$O$_4$ with different metals, with
+the contact effects providing a window on the physics at work in the correlated
+oxide. Contact resistances are determined by means of four-terminal electrical
+measurements as a function of source voltage and temperature. Contact
+resistances vary systematically with the work function of the electrode metal,
+$\phi(M)$, $M=$Cu, Au and Pt, with higher work function yielding lower contact
+resistance. This trend and the observation that contact resistances are
+directly proportional to the Fe$_3$O$_4$ resistivity are consistent with
+modeling the oxide as an effective $p$-type semiconductor with hopping
+transport. The jumps in contact resistance values at the bias-driven
+insulator-metal transition have a similar trend with $\phi$($M$), consistent
+with the transition mechanism of charge gap closure by electric field.",1011.6407v1
+2011-02-22,High-Tc BaTiO3 ferroelectric films with frozen negative pressure states,"We report that an energetic plasma process is extremely effective in
+enlarging the unit cell volume and ferroelectric distortion of the
+ferroelectric oxides, resulting in a significant increase in its Tc. We
+demonstrate experimentally that c-axis oriented BaTiO3 films can be deposited
+directly on quartz glass and Si substrates using such a process and that the
+material shows an approximately 5% expansion of its unit cell volume and
+approximately 4 times the ferroelectric tetragonal distortion of the bulk
+crystals. Such a frozen negative pressure results in a Tc value that is
+approximately 580 K higher than that of bulk single crystals, providing a wide
+range of operating temperatures for the devices. The present results suggest an
+approach to producing ferroelectric oxides with unique properties that might be
+extended to ferromagnetic or superconductor oxides and demonstrate a route to a
+lead-free ferroelectric oxide for capacitive, ferroelectric memory, and
+electro-optical devices.",1102.4473v1
+2011-04-27,Size-reduction of nanodiamonds via air oxidation,"Here we report the size reduction and effects on nitrogen-vacancy centres in
+nanodiamonds by air oxidation using a combined atomic force and confocal
+microscope. The average height reduction of individual crystals as measured by
+atomic force microscopy was 10.6 nm/h at 600 {\deg}C air oxidation at
+atmospheric pressure. The oxidation process modified the surface including
+removal of non-diamond carbon and organic material which also led to a decrease
+in background fluorescence. During the course of the nanodiamond size
+reduction, we observed the annihilation of nitrogen-vacancy centres which
+provided important insight into the formation of colour centres in small
+crystals. In these unirradiated samples, the smallest nanodiamond still hosting
+a stable nitrogen-vacancy centre observed was 8 nm.",1104.5075v1
+2011-07-21,Density functional calculation of the heats of formation of rare-earth orthophosphates,"Electronic structure calculations are carried out to estimate the heats of
+formation of rare-earth orthophosphates from their oxides. The calculated heats
+of formation are systematically about 40 kJ/mol less exothermic than the
+measured values. Based on estimated corrections for zero-point energies and
+H(298.15)-H(0), the discrepancy is almost entirely electronic in origin. The
+decreasingly exothermic {\Delta}Hfox with decreasing ionic radius (i.e. LaPO4
+more exothermic than ScPO4) results from the higher charge localization on the
+oxide anion (O2-) relative to the phosphate anion (PO43-). The lattice energy,
+of course, becomes more negative with decreasing ionic radius for both oxide
+and phosphate phases, but does so more rapidly for the oxide, making the
+reaction less exothermic as ionic radius becomes smaller. This effect should
+carry over to {\Delta}Hfox other oxyacids, such as silicates and sulfates.",1107.4261v1
+2011-07-27,Properties and characterization of ALD grown dielectric oxides for MIS structures,"We report on an extensive structural and electrical characterization of
+under-gate dielectric oxide insulators Al2O3 and HfO2 grown by Atomic Layer
+Deposition (ALD). We elaborate the ALD growth window for these oxides, finding
+that the 40-100 nm thick layers of both oxides exhibit fine surface flatness
+and required amorphous structure. These layers constitute a base for further
+metallic gate evaporation to complete the Metal-Insulator-Semiconductor
+structure. Our best devices survive energizing up to ~3 MV/cm at 77 K with the
+leakage current staying below the state-of-the-art level of 1 nA. At these
+conditions the displaced charge corresponds to a change of the sheet carrier
+density of 3 \times 1013 cm-2, what promises an effective modulation of the
+micromagnetic properties in diluted ferromagnetic semiconductors.",1107.5401v1
+2011-08-10,Microscopic Property of Amorphous Semiconductor Metal Oxide InGaZnO$_{4}$ and Role of O-deficiency,"We investigated the microscopic and electronic structures amorphous oxide
+semiconductors InGaZnO$_{4}$ (a-IGZO) and the role of O-deficiency through the
+first-principle calculations. The structure of the amorphous oxide is
+complicated by the admixture of many different kinds of substructures, however
+it is surprisingly found that the band tail states, which are well-known to be
+present in the amorphous semiconductors, are few generated for the conduction
+band minimum (CBM). The electronic structure around CBM is little affected by
+the disorder and also by the O-deficiency. Free electron carriers can be
+generated without a creation of donor-level in the O-deficient amorphous oxide.",1108.2086v2
+2011-08-30,Probing the Thermal Deoxygenation of Graphene Oxide using High Resolution In Situ X-Ray based Spectroscopies,"Despite the recent developments in Graphene Oxide due to its importance as a
+host precursor of Graphene, the detailed electronic structure and its evolution
+during the thermal reduction remain largely unknown, hindering its potential
+applications. We show that a combination of high resolution in situ X-ray
+photoemission and X-ray absorption spectroscopies offer a powerful approach to
+monitor the deoxygenation process and comprehensively evaluate the electronic
+structure of Graphene Oxide thin films at different stages of the thermal
+reduction process. It is established that the edge plane carboxyl groups are
+highly unstable, whereas carbonyl groups are more difficult to remove. The
+results consistently support the formation of phenol groups through reaction of
+basal plane epoxide groups with adjacent hydroxyl groups at moderate degrees of
+thermal activation (~400 {\deg}C). The phenol groups are predominant over
+carbonyl groups and survive even at a temperature of 1000 {\deg}C. For the
+first time a drastic increase in the density of states (DOS) near the Fermi
+level at 600 {\deg}C is observed, suggesting a progressive restoration of
+aromatic structure in the thermally reduced graphene oxide",1108.5911v1
+2011-10-17,In Situ Imaging of the Conducting Filament in a Silicon Oxide Resistive Switch,"The nature of the conducting filaments in many resistive switching systems
+has been elusive. Through in situ transmission electron microscopy, we image
+the real-time formation and evolution of the filament in a silicon oxide
+resistive switch. The electroforming process is revealed to involve the local
+enrichment of silicon from the silicon oxide matrix. Semi-metallic silicon
+nanocrystals with structural variations from the conventional diamond cubic
+form of silicon are observed, which likely accounts for the conduction in the
+filament. The growth and shrinkage of the silicon nanocrystals in response to
+different electrical stimuli show energetically viable transition processes in
+the silicon forms, offering evidence to the switching mechanism. The study here
+also provides insights into the electrical breakdown process in silicon oxide
+layers, which are ubiquitous in a host of electronic devices.",1110.3755v1
+2011-10-25,Intrinsic Defects and Electronic Conductivity of TaON: First-Principles Insights,"As a compound in between the tantalum oxide and nitride, the tantalum
+oxynitride TaON is expected to combine their advantages and act as an efficient
+visible-light-driven photocatalyst. In this letter, using hybrid functional
+calculations we show that TaON has different defect properties from the binary
+tantalum oxide and nitride: (i) instead of O or N vacancies or Ta
+interstitials, the $O_N$ antisite is the dominant defect, which determines its
+intrinsic n-type conductivity and the p-type doping difficulty; (ii) the $O_N$
+antisite has a shallower donor level than O or N vacancies, with a delocalized
+distribution composed mainly of the Ta $5d$ orbitals, which gives rise to
+better electronic conductivity in the oxynitride than in the oxide and nitride.
+The phase stability analysis reveals that the easy oxidation of TaON is
+inevitable under O rich conditions, and a relatively O poor condition is
+required to synthesize stoichiometric TaON samples.",1110.5603v1
+2011-12-16,Low-temperature photoluminescence of oxide-covered single-layer MoS2,"We present a photoluminescence study of single-layer MoS2 flakes on SiO2
+surfaces. We demonstrate that the luminescence peak position of flakes prepared
+from natural MoS2, which varies by up to 25 meV between individual as-prepared
+flakes, can be homogenized by annealing in vacuum, which removes adsorbates
+from the surface. We use HfO2 and Al2O3 layers prepared by atomic layer
+deposition to cover some of our flakes. We clearly observe a suppression of the
+low-energy luminescence peak observed for as-prepared flakes at low
+temperatures, indicating that this peak originates from excitons bound to
+surface adsorbates. We also observe different temperature-induced shifts of the
+luminescence peaks for the oxide-covered flakes. This effect stems from the
+different thermal expansion coefficients of the oxide layers and the MoS2
+flakes. It indicates that the single-layer MoS2 flakes strongly adhere to the
+oxide layers and are therefore strained.",1112.3747v3
+2012-02-21,Wide band gap tunability in complex transition metal oxides by site-specific substitution,"Fabricating complex transition metal oxides with a tuneable band gap without
+compromising their intriguing physical properties is a longstanding challenge.
+Here we examine the layered ferroelectric bismuth titanate and demonstrate
+that, by site-specific substitution with the Mott insulator lanthanum
+cobaltite, its band gap can be narrowed as much as one electron volt, while
+remaining strongly ferroelectric. We find that when a specific site in the host
+material is preferentially substituted, a split-off state responsible for the
+band gap reduction is created just below the conduction band of bismuth
+titanate. This provides a route for controlling the band gap in complex oxides
+for use in emerging oxide opto-electronic and energy applications.",1202.4785v1
+2012-06-20,Ultrathin Oxide Films by Atomic Layer Deposition on Graphene,"In this paper, a method is presented to create and characterize mechanically
+robust, free standing, ultrathin, oxide films with controlled, nanometer-scale
+thickness using Atomic Layer Deposition (ALD) on graphene. Aluminum oxide films
+were deposited onto suspended graphene membranes using ALD. Subsequent etching
+of the graphene left pure aluminum oxide films only a few atoms in thickness. A
+pressurized blister test was used to determine that these ultrathin films have
+a Young's modulus of 154 \pm 13 GPa. This Young's modulus is comparable to much
+thicker alumina ALD films. This behavior indicates that these ultrathin
+two-dimensional films have excellent mechanical integrity. The films are also
+impermeable to standard gases suggesting they are pinhole-free. These
+continuous ultrathin films are expected to enable new applications in fields
+such as thin film coatings, membranes and flexible electronics.",1206.4587v1
+2012-07-16,CVD Synthesis of Small-Diameter Single Walled Carbon Nanotubes on Silicon,"A simple process for chemical vapor deposition of ultra SD single wall carbon
+nanotubes has been developed. In this process, an iron nitrate nonahydrate
+solution in isopropyl alcohol with a concentration of 400 ug/mlit was used to
+catalyze nanoparticles formation on an oxidized silicon wafer. The oxide on the
+substrate was made of a thick layer of wet oxide sandwiched between tow thin
+layers of dry oxide. The process results in semiconducting single-walled carbon
+nanotubes (SWNTs) with diameter of less than 0.7nm and more than 1ev band gap
+energy, which are amongst the smallest diameters of SWNTs ever reported.",1207.3555v1
+2012-10-04,Graphene Oxide vs. Reduced Graphene Oxide as saturable absorbers for Er-doped passively mode-locked fiber laser,"In this work we demonstrate comprehensive studies on graphene oxide (GO) and
+reduced graphene oxide (rGO) based saturable absorbers (SA) for mode-locking of
+Er-doped fiber lasers. The paper describes the fabrication process of both
+saturable absorbers and detailed comparison of their parameters. Our results
+show, that there is no significant difference in the laser performance between
+the investigated SA. Both provided stable, mode-locked operation with sub-400
+fs soliton pulses and more than 9 nm optical bandwidth at 1560 nm center
+wavelength. It has been shown that GO might be successfully used as an
+efficient SA without the need of its reduction to rGO. Taking into account
+simpler manufacturing technology and the possibility of mass production, GO
+seems to be a good candidate as a cost-effective material for saturable
+absorbers for Er-doped fiber lasers.",1210.1469v1
+2012-12-17,Reactive self-heating model of aluminum spherical nanoparticles,"Aluminum-oxygen reaction is important in many highly energetic, high pressure
+generating systems. Recent experiments with nanostructured thermites suggest
+that oxidation of aluminum nanoparticles occurs in a few microseconds. Such
+rapid reaction cannot be explained by a conventional diffusion-based mechanism.
+We present a rapid oxidation model of a spherical aluminum nanoparticle, using
+Cabrera-Mott moving boundary mechanism, and taking self-heating into account.
+In our model, electric potential solves the nonlinear Poisson equation. In
+contrast with the Coulomb potential, a ""double-layer"" type solution for the
+potential and self-heating leads to enhanced oxidation rates. At maximal
+reaction temperature of 2000 C, our model predicts overall oxidation time scale
+in microseconds range, in agreement with experimental evidence.",1212.4113v1
+2013-02-19,"Structure and Dielectric Properties of Amorphous High-kappa Oxides: HfO2, ZrO2 and their alloys","High-$\kappa$ metal oxides are a class of materials playing an increasingly
+important role in modern device physics and technology. Here we report
+theoretical investigations of the properties of structural and lattice
+dielectric constants of bulk amorphous metal oxides by a combined approach of
+classical molecular dynamics (MD) - for structure evolution, and quantum
+mechanical first principles density function theory (DFT) - for electronic
+structure analysis. Using classical MD based on the Born-Mayer-Buckingham
+potential function within a melt and quench scheme, amorphous structures of
+high-$\kappa$ metal oxides Hf$_{1-x}$Zr$_x$O$_2$ with different values of the
+concentration $x$, are generated. The coordination numbers and the radial
+distribution functions of the structures are in good agreement with the
+corresponding experimental data. We then calculate the lattice dielectric
+constants of the materials from quantum mechanical first principles, and the
+values averaged over an ensemble of samples agree well with the available
+experimental data, and are very close to the dielectric constants of their
+cubic form.",1302.4534v1
+2013-02-20,Search for correlations between morphological characteristics and the crystallite sizes in thin zinc oxide films,"Size-property relations in plasma-modified ZnO thin films have been
+investigated as a function of plasma treatment duration. The correlations
+between crystallite sizes and the morphological characteristics of films have
+been extracted on the basis of the frontier computational analysis of the
+scanning probe microscope (SPM) data matrices. The nanocluster structure of
+oxide films have been studied in detail with high accuracy. The strong
+plasma-induced changes in crystallite sizes have been interpreted as a
+size-structure phase transition. Direct measurements of X-ray diffraction and
+optical transmittance spectra have confirmed the results obtained with
+computational approaches. The discovery size-morphology correlations in thin
+oxide films might open new avenues ultimately leading towards deeper insight
+into unsolved problems of evaluation of optimal technological conditions for
+thin oxide film designing.",1302.4821v1
+2013-04-22,Low Hole Effective Mass p-type Transparent Conducting Oxides: Identification and Design Principles,"The development of high performance transparent conducting oxides (TCOs) is
+critical to many technologies from transparent electronics to solar cells.
+While n-type TCOs are present in many devices, current p-type TCOs are not
+largely commercialized as they exhibit much lower carrier mobilities, due to
+the large hole effective masses of most oxides. Here, we conduct a
+high-throughput computational search on thousands of binary and ternary oxides
+and identify several highly promising compounds displaying exceptionally low
+hole effective masses (up to an order of magnitude lower than state of the art
+p-type TCOs) as well as wide band gaps. In addition to the discovery of
+specific compounds, the chemical rationalization of our findings opens new
+directions, beyond current Cu-based chemistries, for the design and development
+of future p-type TCOs.",1304.6054v1
+2013-06-03,Physical properties of Co/n-Ge Schottky contacts,"To investigate the role of the interface state on the physical properties of
+Schottky contacts, Co/n-Ge Schottky diodes that have undergone various cleaning
+methods (HF etching and in-situ thermal cleaning) were studied by Transmission
+Electron Microscopy (TEM), Deep-level Transient Spectroscopy (DLTS) and by a
+detailed analysis of the temperature dependence of the diodes characteristics.
+It is shown that Schottky barrier height characteristics are sensitive to the
+nature of the interface. The strongest Fermi level pinning and the highest
+spatial inhomogeneities are observed for intimate metal/semiconductor contacts.
+The presence of a thin oxide interlayer, even of Ge native oxide, allows the
+Fermi level to be released towards the conduction band and leads to more
+homogeneous contacts. Finally our results suggest that a pure GeO2 oxide
+interlayer should present a better depinning efficiency than the native Ge
+oxide.",1306.0459v1
+2013-11-27,Multi-wavelength Raman scattering of nanostructured Al-doped zinc oxide,"In this work we present a detailed Raman scattering investigation of zinc
+oxide and aluminum-doped zinc oxide (AZO) films characterized by a variety of
+nanoscale structure and morphology and synthesized by pulsed laser deposition
+(PLD) under different oxygen pressure conditions. The comparison of Raman data
+for pure ZnO and AZO films with similar morphology at the nano/mesoscale allows
+to investigate the relation between Raman features (peak or band positions,
+width, relative intensity) and material properties such as local structural
+order, stoichiometry and doping. Moreover Raman measurements with three
+different excitation lines (532, 457 and 325 nm) point out a strong correlation
+between vibrational and electronic properties. This observation confirms the
+relevance of a multi-wavelength Raman investigation to obtain a complete
+structural characterization of advanced doped oxide materials.",1311.7028v1
+2014-04-17,Polarization degenerate micropillars fabricated by designing elliptical oxide apertures,"A method for fabrication of polarization degenerate oxide apertured
+micropillar cavities is demon- strated. Micropillars are etched such that the
+size and shape of the oxide front is controlled. The polarization splitting in
+the circular micropillar cavities due to the native and strain induced bire-
+fringence can be compensated by elongating the oxide front in the [110]
+direction, thereby reducing stress in this direction. By using this technique
+we fabricate a polarization degenerate cavity with a quality factor of
+1.7*?10^4 and a mode volume of 2.7 u?m3, enabling a calculated maximum Purcell
+factor of 11.",1404.4597v1
+2014-07-19,Charge transfer from an adsorbed ruthenium-based photosensitizer through an ultra-thin aluminium oxide layer and into a metallic substrate,"The interaction of the dye molecule N3
+(cis-bis(isothiocyanato)bis(2,2-bipyridyl-4,4'-dicarboxylato)-ruthenium(II))
+with the ultra-thin oxide layer on a AlNi(110) substrate, has been studied
+using synchrotron radiation based photoelectron spectroscopy, resonant
+photoemission spectroscopy (RPES) and near edge X-ray absorption fine structure
+spectroscopy (NEXAFS). Calibrated X-ray absorption and valence band spectra of
+the monolayer and multilayer coverages reveal that charge transfer is possible
+from the molecule to the AlNi(110) substrate via tunnelling through the
+ultra-thin oxide layer and into the conduction band edge of the substrate. This
+charge transfer mechanism is possible from the LUMO+2&3 in the excited state
+but not from the LUMO, therefore enabling core-hole clock analysis, which gives
+an upper limit of $6.0\pm$2.5fs for the transfer time. This indicates that
+ultra-thin oxide layers are a viable material for use in dye-sensitized solar
+cells (DSSC), which may lead to reduced recombination effects and improved
+efficiencies of future devices.",1407.5186v1
+2014-09-03,Manganese oxide nanosheets and a 2D hybrid of graphene-manganese oxide nanosheets synthesized by liquid-phase exfoliation,"Manganese oxide nanosheets were synthesized using liquid phase exfoliation
+that achieved suspensions in isopropanol with concentrations of up to 0.45
+mg/ml. A study of solubility parameters showed that the exfoliation was optimum
+in DMF followed by isopropanol and diethylene glycol. Isopropanol was the
+solvent of choice due to its environmentally friendly nature and ease of use
+for further processing. The 2D hybrid was synthesized in isopropanol
+suspensions with concentrations of up to 0.5 mg/ml and demonstrated stability
+against reaggregation for up to six months. The coexfoliation was found to be
+an energetically favorable process in which both solutes, graphene and
+manganese oxide nanosheets, exfoliate with an improved yield as compared to the
+single solute exfoliation procedure. This work demonstrates the remarkable
+versatility of liquid phase exfoliation with respect to the synthesis of
+hybrids with tailored properties, and it provides proof of concept ground work
+for further future investigation and exploitation of hybrids made of two or
+more 2D nanomaterials that have key complementary properties for various
+technological applications.",1409.1087v1
+2014-10-16,Large spin accumulation voltages in epitaxial Mn5Ge3 contacts on Ge without oxide tunnel barrier,"Spin injection in high-quality epitaxial Mn5Ge3 Schottky contacts on n-type
+Ge has been investigated using a three-terminal Hanle effect measurement. Clear
+Hanle and inverted Hanle signals with features characteristic of spin
+accumulation and spin precession are observed up to 200 K. Strikingly, the
+observed spin voltage is several orders of magnitude larger than predicted by
+the theory of spin injection and diffusive spin transport. Since the devices
+have no oxide tunnel barrier, the discrepancy between theory and experiments
+cannot be explained by the often-invoked spin accumulation in localized states
+associated with the oxide or oxide/semiconductor interface. The observed spin
+voltages therefore must originate from the Ge itself, either from spins in the
+Ge bulk bands or its depletion region.",1410.4277v1
+2015-01-14,Yeast caspase 1 suppresses the burst of reactive oxygen species and maintains mitochondrial stability in Saccharomyces cerevisiae,"Caspases are a family of cysteine proteases that play essential roles during
+apoptosis, and we presume some of them may also protect the cell from oxidative
+stress. We found that the absence of yeast caspase 1(Yca1)in Saccharomyces
+cerevisiae leads to a more intense burst of mitochondrial reactive oxygen
+species (ROS) In addition, compared to wild type yeast cells, the ability of
+yca1 mutant cells to maintain mitochondrial activity is significantly reduced
+after either oxidative stress treatment or aging. During mitochondrial ROS
+burst, deletion of the yca1 gene delayed structural damage of a green
+fluorescent protein (GFP) reporter bound in the inner mitochondrial membrane.
+This work implies that yeast caspase 1 is closely connected to the oxidative
+stress response. We speculate that Yca1 can discriminate proteins damaged by
+oxidation and accelerate their hydrolysis to attenuate the ROS burst.",1501.03258v1
+2015-02-04,The reversible lithiation of SnO: a three-phase process,"A high reversible capacity is a key feature for any rechargeable battery. In
+the lithium-ion battery technology, tin-oxide anodes do fulfill this
+requirement, but a fast loss of capacity hinders a full commercialization.
+Using first-principles calculations, we propose a microscopic model that sheds
+light on the reversible lithiation/delithiation of SnO and reveals that a
+sintering of Sn causes a strong degradation of SnO-based anodes. When the
+initial irreversible transformation ends, active anode grains consist of
+Li-oxide layers separated by Sn bilayers. During the following reversible
+lithiation, the Li-oxide undergoes two phase transformations that give rise to
+a Li-enrichment of the oxide and the formation of a layered SnLi composite. We
+find that the model-predicted anode volume expansion and voltage profile agree
+well with experiment, and a layered anode grain is highly-conductive and has a
+theoretical reversible capacity of 4.5 Li atoms per a SnO host unit. The model
+suggests that the grain structure has to remain layered to sustain its
+reversible capacity and a thin-film design of battery anodes could be a remedy
+for the capacity loss.",1502.01110v2
+2015-02-05,Influence of oxygen on thermal stability of nanocrystalline aluminum studied by positron annihilation spectroscopy,"The thermal stability of nanocrystalline (nc) Al has been studied by means of
+positron lifetime spectroscopy and X-ray diffraction (XRD), prepared by
+compacting nanoparticles under high pressures. Those nanoparticles were
+produced by the flow-levitation (FL) method [1] and the arc-discharge (DC)
+method. Effect of oxide at nanoparticle surface on structure stability was
+investigated especially in this experiment. The positron lifetime results
+reveal that vacancy clusters in grain boundaries are dominant positron traps
+according to the high relative intensity of the positron lifetime {\tau}2 in
+both samples. The mean grain size of the sample consisting of nanoparticles
+with partially oxidized surfaces is almost unchanged after aging at 150 for 84
+h, with that of the sample consisting of pure nc Al increasing. The partially
+oxidized surfaces of nanoparticles hinder the growth of grain when aging at
+150, vacancy clusters related to Al2O3 need longer aging time to decompose,
+which implies that the oxide stabilizes the microstructure of the
+nanomaterials. The effect is beneficial for nc materials to keep excellent
+properties.",1502.01511v1
+2015-03-06,Constructing ab initio models of ultra-thin Al-AlOx-Al barriers,"The microscopic structure of ultra-thin oxide barriers often plays a major
+role in modern nano-electronic devices. In the case of superconducting
+electronic circuits, their operation depends on the electrical non-linearity
+provided by one or more such oxide layers in the form of ultra-thin tunnel
+barriers (also known as Josephson junctions). Currently available fabrication
+techniques manufacture an amorphous oxide barrier, which is attributed as a
+major noise source within the device. The nature of this noise is currently an
+open question and requires both experimental and theoretical investigation.
+Here, we present a methodology for constructing atomic scale computational
+models of Josephson junctions using a combination of molecular mechanics,
+empirical and ab initio methods. These junctions consist of ultra-thin
+amorphous aluminium-oxide layers sandwiched between crystalline aluminium. The
+stability and structure of these barriers as a function of density and
+stoichiometry are investigated, which we compare to experimentally observed
+parameters",1503.01859v2
+2015-04-05,Pathway to oxide photovoltaics via band-structure engineering of SnO,"The prospects of scaling current photovoltaic technologies to terawatt levels
+remain uncertain. All-oxide photovoltaics could open rapidly scalable
+manufacturing routes, if only oxide materials with suitable electronic and
+optical properties were developed. A potential candidate material is tin
+monoxide (SnO), which has exceptional doping and transport properties among
+oxides, but suffers from a low adsorption coefficient due to its strongly
+indirect band gap. Here, we address this shortcoming of SnO by band-structure
+engineering through isovalent but heterostructural alloying with divalent
+cations (Mg, Ca, Sr, Zn). Using first-principles calculations, we show that
+suitable band gaps and optical properties close to that of direct-gap
+semiconductors are achievable in such SnO based alloys. Due to the defect
+tolerant electronic structure of SnO, the dispersive band-structure features
+and comparatively small effective masses are preserved in the alloys. Initial
+Sn1-xZnxO thin films deposited by sputtering exhibit crystal structure and
+optical properties in accord with the theoretical predictions, which confirms
+the feasibility of the alloying approach. Thus, the implications of this work
+are important not only for terawatt scale photovoltaics, but also for other
+large-scale energy technologies where defect-tolerant semiconductors with high
+quality electronic properties are required.",1504.01168v2
+2015-04-29,Graphene Oxide as an Optimal Candidate Material for Methane Storage,"Methane, the primary constituent of natural gas, binds too weakly to
+nanostructured carbons to meet the targets set for on-board vehicular storage
+to be viable. We show, using density functional theory calculations, that
+replacing graphene by graphene oxide increases the adsorption energy of methane
+by 50%. This enhancement is sufficient to achieve the optimal binding strength.
+In order to gain insight into the sources of this increased binding, that could
+also be used to formulate design principles for novel storage materials, we
+consider a sequence of model systems, that progressively take us from graphene
+to graphene oxide. A careful analysis of the various contributions to the weak
+binding between the methane molecule and the graphene oxide shows that the
+enhancement has important contributions from London dispersion interactions as
+well as Debye interactions and higher-order electrostatic interactions, aided
+by geometric curvature induced primarily by the presence of epoxy groups.",1504.07994v1
+2015-06-09,"Comment on ""Selective Interface Control of Order Parameters in Complex Oxides"" (arXiv:1505.07451)","We show that the experimental evidence presented in this paper is
+insufficient to support its conclusions.",1506.02787v1
+2015-07-10,Compensation of radiation damages for SOI pixel detector via tunneling,"We are developing monolithic pixel detectors based on SOI technology for high
+energy physics, X-ray applications and so on.To employ SOI pixel detector on
+such radiation environments, we have to solve effects of total ionizing dose
+(TID) for transistors which are enclosed in oxide layer.The holes which are
+generated and trapped in the oxide layers after irradiation affect
+characteristics of near-by transistors due to its positive electric
+field.Annealing and radiation of ultraviolet are not realistic to remove
+trapped holes for a fabricated detector due to thermal resistance of components
+and difficulty of handling. We studied compensation of TID effects by tunneling
+using a high-voltage. For decrease of trapped holes, applied high-voltage to
+buried p-well which is under oxide layer to inject the electrons into the oxide
+layer.In this report, recent progress of this study is shown.",1507.02797v2
+2015-07-24,Spin relaxation characteristics in Ag nanowire covered with various oxides,"We have studied spin relaxation characteristics in a Ag nanowire covered with
+various oxide layers of Bi2O3, Al2O3, HfO2, MgO or AgOx by using non-local spin
+valve structures. The spin-flip probability, a ratio of momentum relaxation
+time to spin relaxation time at 10 K, exhibits a gradual increase with an
+atomic number of the oxide constituent elements, Mg, Al, Ag and Hf.
+Surprisingly the Bi2O3 capping was found to increase the probability by an
+order of magnitude compared with other oxide layers. This finding suggests the
+presence of an additional spin relaxation mechanism such as Rashba effect at
+the Ag/Bi2O3 interface, which cannot be explained by the simple Elliott-Yafet
+mechanism via phonon, impurity and surface scatterings. The Ag/Bi2O3 interface
+may provide functionality as a spin to charge interconversion layer.",1507.06813v2
+2015-07-27,Local environment and oxidation state of Mn impurity in SrTiO3 determined from XAFS data,"The local environment and oxidation state of Mn impurity in strontium
+titanate doped with 3% Mn were studied by X-ray absorption fine structure
+spectroscopy. The influence of the preparation conditions on the incorporation
+of the impurity into the $A$ and $B$ sites was studied. It was established that
+Mn ions substituting for Ti are in the Mn$^{4+}$ oxidation state and on-center.
+Mn ions substituting for Sr are in the Mn$^{2+}$ oxidation state, are
+off-center and displaced from the lattice sites by $\sim$0.32 {\AA}. It was
+demonstrated that studies of the X-ray absorption near-edge structure can be
+used to determine the concentration ratio of Mn atoms located at the $A$ and
+$B$ sites.",1507.07342v1
+2015-07-31,"Intrinsic defects, fluctuations of the local shape, and the photo-oxidation of black phosphorus","Black phosphorus is a monoatomic semiconducting layered material that
+degrades exothermically in the presence of light and ambient contaminants. Its
+degradation dynamics remain largely unknown. Even before degradation,
+local-probe studies indicate non-negligible local curvature --through a
+non-constant height distribution-- due to the unavoidable presence of intrinsic
+defects. We establish that these intrinsic defects are photo-oxidation sites
+because they lower the chemisorption barrier of ideal black phosphorus (> 10 eV
+and out of visible-range light excitations) right into the visible and
+ultra-violet range (1.6 to 6.8 eV), thus enabling photo-induced oxidation and
+dissociation of oxygen dimers. A full characterization of the material's shape
+and of its electronic properties at the early stages of the oxidation process
+is presented as well. This study thus provides fundamental insights into the
+degradation dynamics of this novel layered material.",1507.08994v1
+2015-08-15,Structure Sensitivity in Oxide Catalysis: First-Principles Kinetic Monte Carlo Simulations for CO Oxidation at RuO$_2$(111),"We present a density-functional theory based kinetic Monte Carlo study of CO
+oxidation at the (111) facet of RuO$_2$. We compare the detailed insight into
+elementary processes, steady-state surface coverages and catalytic activity to
+equivalent published simulation data for the frequently studied RuO$_2$(110)
+facet. Qualitative differences are identified in virtually every aspect ranging
+from binding energetics over lateral interactions to the interplay of
+elementary processes at the different active sites. Nevertheless, particularly
+at technologically relevant elevated temperatures, near-ambient pressures and
+near-stoichiometric feeds both facets exhibit almost identical catalytic
+activity. These findings challenge the traditional definition of structure
+sensitivity based on macroscopically observable turnover frequencies and allow
+to scrutinize the applicability of structure sensitivity classifications
+developed for metals to oxide catalysis.",1508.03697v1
+2016-01-07,"First principles search for $n$-type oxide, nitride, and sulfide thermoelectrics","Oxides have many potentially desirable characteristics for thermoelectric
+applications, including low cost and stability at high temperatures, but thus
+far there are few known high $zT$ $n$-type oxide thermoelectrics. In this work,
+we use high-throughput first principles calculations to screen transition metal
+oxides, nitrides, and sulfides for candidate materials with high power factors
+and low thermal conductivity. We find a variety of promising materials, and we
+investigate these materials in detail in order to understand the mechanisms
+that cause them to have high power factors. These materials all combine a high
+density of states near the Fermi level with dispersive bands, reducing the
+trade-off between the Seebeck coefficient and the electrical conductivity, but
+they do so for several different reasons. In addition, our calculations
+indicate that many of our candidate materials have low thermal conductivity.",1601.01622v2
+2016-01-25,Raman spectroscopy and electrical properties of InAs nanowires with local oxidation enabled by substrate micro-trenches and laser irradiation,"The thermal gradient along indium-arsenide nanowires was engineered by a
+combination of fabricated micro- trenches in the supporting substrate and
+focused laser irradiation. This allowed local control of thermally activated
+oxidation reactions of the nanowire on the scale of the diffraction limit. The
+locality of the oxidation was detected by micro-Raman mapping, and the results
+were found consistent with numerical simulations of the temperature profile.
+Applying the technique to nanowires in electrical devices the locally oxidized
+nanowires remained conducting with a lower conductance as expected for an
+effectively thinner conducting core.",1601.06583v1
+2016-02-13,Strain Control of Oxygen Vacancies in Epitaxial Strontium Cobaltite Films,"The ability to manipulate oxygen anion defects rather than metal cations in
+complex oxides can facilitate creating new functionalities critical for
+emerging energy and device technologies. However, the difficulty in activating
+oxygen at reduced temperatures hinders the deliberate control of important
+defects, oxygen vacancies. Here, strontium cobaltite (SrCoOx) is used to
+demonstrate that epitaxial strain is a powerful tool for manipulating the
+oxygen vacancy concentration even under highly oxidizing environments and at
+annealing temperatures as low as 300 C. By applying a small biaxial tensile
+strain (2%), the oxygen activation energy barrier decreases by ~30%, resulting
+in a tunable oxygen deficient steady-state under conditions that would normally
+fully oxidize unstrained cobaltite. These strain-induced changes in oxygen
+stoichiometry drive the cobaltite from a ferromagnetic metal towards an
+antiferromagnetic insulator. The ability to decouple the oxygen vacancy
+concentration from its typical dependence on the operational environment is
+useful for effectively designing oxides materials with a specific oxygen
+stoichiometry.",1602.04280v1
+2016-06-27,Structural and electrical properties of Sn substituted double sintering derived Ni-Zn ferrite,"The Sn substituted Ni-Zn ferrites were synthesized by the standard double
+sintering technique using nano powders of nickel oxide (NiO), zinc oxide (ZnO),
+iron oxide (Fe2O3) and tin oxide (SnO2). The structural and electrical
+properties have been investigated by the X-ray diffraction, scanning electron
+microscopy, DC resistivity and dielectric measurements. Extra intermediate
+phase has been detected along with the inverse cubic spinel phase of Ni-Zn
+ferrite. Enhancement of grain size is observed in Sn substituted Ni-Zn
+ferrites. DC resistivity as a function of temperature has been investigated by
+two probe method. The DC resistivity was found to decrease whereas the
+dielectric constants increase with increasing Sn content in Ni-Zn ferrites. The
+dielectric constant of the as prepared samples is high enough to use these
+materials in miniaturized memory devices based capacitive components or energy
+storage principles.",1606.08118v1
+2016-06-27,Hafnium carbide formation in oxygen deficient hafnium oxide thin films,"On highly oxygen deficient thin films of hafnium oxide (hafnia, HfO$_{2-x}$)
+contaminated with adsorbates of carbon oxides, the formation of hafnium carbide
+(HfC$_x$) at the surface during vacuum annealing at temperatures as low as 600
+{\deg}C is reported. Using X-ray photoelectron spectroscopy the evolution of
+the HfC$_x$ surface layer related to a transformation from insulating into
+metallic state is monitored in situ. In contrast, for fully stoichiometric
+HfO$_2$ thin films prepared and measured under identical conditions, the
+formation of HfC$_x$ was not detectable suggesting that the enhanced adsorption
+of carbon oxides on oxygen deficient films provides a carbon source for the
+carbide formation. This shows that a high concentration of oxygen vacancies in
+carbon contaminated hafnia lowers considerably the formation energy of hafnium
+carbide. Thus, the presence of a sufficient amount of residual carbon in
+resistive random access memory devices might lead to a similar carbide
+formation within the conducting filaments due to Joule heating.",1606.08227v1
+2016-09-09,Oxidation-assisted graphene heteroepitaxy on copper foil,"We propose an innovative, easy-to-implement approach to synthesize large-area
+singlecrystalline graphene sheets by chemical vapor deposition on copper foil.
+This method doubly takes advantage of residual oxygen present in the gas phase.
+First, by slightly oxidizing the copper surface, we induce grain boundary
+pinning in copper and, in consequence, the freezing of the thermal
+recrystallization process. Subsequent reduction of copper under hydrogen
+suddenly unlocks the delayed reconstruction, favoring the growth of
+centimeter-sized copper (111) grains through the mechanism of abnormal grain
+growth. Second, the oxidation of the copper surface also drastically reduces
+the nucleation density of graphene. This oxidation/reduction sequence leads to
+the synthesis of aligned millimeter-sized monolayer graphene domains in
+epitaxial registry with copper (111). The as-grown graphene flakes are
+demonstrated to be both single-crystalline and of high quality.",1609.02761v1
+2016-09-29,Electrical domain writing and nanoscale potential modulation on LaVO$_3$/SrTiO$_3$,"The high-mobility 2DEGs formed at the interfaces between certain insulating
+perovskite oxides have been known to be a novel playground of exotic physical
+orders like, superconductivity and ferromagnetism and their inter-coupling.
+There have been efforts to accomplish even more exotic properties at such
+interfaces of oxide heterostructures through nano-structuring of the surface.
+In this paper we report writing and erasing charge domains on such an oxide
+heterostructure LaVO$_3$/SrTiO$_3$ using a conductive AFM cantilever. We have
+patterned these domains in a periodic fashion in order to create artificial
+lattices on the surface. Through kelvin probe microscopy, electrostatic force
+microscopy and conductivity mapping of such artificial lattices we found that
+the domains not only trap charge carriers but also develop a controllable
+potential landscape on the surface which coincides with a modulation of local
+electrical conductivity. The ability to pattern such nanostructures reversibly
+offers unprecedented opportunities of realizing ultra-high storage density
+devices in high mobility oxide heterostructures.",1609.09271v1
+2016-10-06,Improved Performance and Reliability of p-i-n Perovskite Solar Cells via Doped Metal Oxides,"Perovskite photovoltaics (PVs) have attracted attention because of their
+excellent power conversion efficiency (PCE). Critical issues related to large
+area PV performance, reliability and lifetime need to be addressed. Here, we
+show that doped metal oxides can provide ideal electron selectivity, improved
+reliability and stability for perovskite PVs. We report p-i-n perovskite PVs
+with device areas ranging from 0.09cm2 to 0.5cm2 incorporating a thick aluminum
+doped zinc oxide (AZO) electron selective contact with hysteresis-free PCE of
+over 13% and high fill factor values in the range of 80%. AZO provides suitable
+energy levels for carrier selectivity, neutralizes the presence of pinholes and
+provides intimate interfaces. Devices using AZO exhibit an average PCE increase
+of over 20% compared with the devices without AZO and maintain the high PCE for
+the larger area devices reported. Furthermore, the device stability of p-i-n
+perovskite solar cells under the ISOS-D-1 is enhanced when AZO is used, and
+maintains 100% of the initial PCE for over 1000 hours of exposure when AZO/Au
+is used as the top electrode. Our results indicate the importance of doped
+metal oxides as carrier selective contacts to achieve reliable and high
+performance long lived large area perovskite solar cells.",1610.01776v1
+2016-10-17,Molten o-H3PO4 - A New Electrolyte for the Anodic Synthesis of Self-Organized Oxide Structures: WO3 Nanochannel Layers and Others,"We introduce the use of pure molten ortho-phosphoric acid (o-H3PO4) as an
+electrolyte for selforganizing electrochemistry. This electrolyte allows for
+the formation of self-organized oxide architectures (one-dimensional nanotubes,
+nanochannels, nanopores) on metals such as tungsten that up to now were
+regarded as very difficult to grow self-ordered anodic oxide structures. In
+this work, we show particularly the fabrication of thick, vertically aligned
+tungsten oxide nanochannel layers, with pore diameter of ca. 10 nm, and
+illustrate their potential use in some typical applications.",1610.05079v1
+2016-10-26,First principles study of band line up at defective metal-oxide interface: oxygen point defects at Al/SiO_2 interface,"The dielectric breakdown at metal-oxide interfaces is a critical electronic
+device failure mechanism. Electronic tunneling through dielectric layers is a
+well-accepted explanation for this phenomenon. Theoretical band alignment
+studies, providing information about tunneling, have already been conducted in
+the literature for metal-oxide interfaces. However, most of the time materials
+were assumed defect free. Oxygen vacancies being very common in oxides, their
+effect on band lineup is of prime importance in understanding electron
+tunneling in realistic materials and devices. This work explores the effect of
+oxygen vacancy and oxygen di-vacancy at the Al/SiO2 interface on the band line
+up within Density Functional Theory using PBE0 hybrid exchange and correlation
+functional. It is found that the presence of defects at the interface, and
+their charge state, strongly alters the band line up.",1610.08550v1
+2017-02-13,An Atomic-Scale View of CO and H2 Oxidation on a Pt-Fe3O4 Model Catalyst,"Metal-support interactions are frequently invoked to explain the enhanced
+catalytic activity of metal nanoparticles dispersed over reducible metal-oxide
+supports, yet the atomic scale mechanisms are rarely known. Here, we use
+scanning tunneling microscopy to study a Pt1-6/Fe3O4 model catalyst exposed to
+CO, H2, O2, and mixtures thereof, at 550 K. CO extracts lattice oxygen at the
+cluster perimeter to form CO2, creating large holes in the metal-oxide surface.
+H2 and O2 dissociate on the metal clusters and spill over onto the support. The
+former creates create surface hydroxyl groups, which react with the support to
+desorb water, while atomic oxygen reacts with Fe from the bulk to create new
+Fe3O4(001) islands. The presence of the Pt is crucial because it catalyses
+reactions that already occur on the bare iron-oxide surface, but at higher
+temperatures.",1702.03998v1
+2017-03-01,Ferroelectric metal-oxide-semiconductor capacitors using ultrathin single crystalline SrZrxTi1-xO3,"The epitaxial growth of multifunctional oxides on semiconductors has opened a
+pathway to introduce new functionalities to semiconductor device technologies.
+In particular, ferroelectric materials integrated on semiconductors could lead
+to low-power field-effect devices that can be used for logic and memory.
+Essential to realizing such field-effect devices is the development of
+ferroelectric metal-oxide-semiconductor (MOS) capacitors, in which the
+polarization of a ferroelectric gate is coupled to the surface potential of a
+semiconducting channel. Here we demonstrate that ferroelectric MOS capacitors
+can be realized using single crystalline SrZrxTi1-xO3 (x = 0.7) that has been
+epitaxially grown on Ge. We find that the ferroelectric properties of
+SrZrxTi1-xO3 are exceptionally robust, as gate layers as thin as 5 nm
+corresponding to an equivalent-oxide-thickness of just 1.0 nm exhibit a ~ 2 V
+hysteretic window in the capacitance-voltage characteristics. The development
+of ferroelectric MOS capacitors with nanoscale gate thicknesses opens new
+vistas for nanoelectronic devices.",1703.00126v1
+2017-03-23,Microscopic Mechanism of Carbon Annihilation upon SiC Oxidation due to Phosphorous Treatment: Density-Functional Calculations Combined with Ion Mass Spectrometry,"We report first-principles static and dynamic calculations that clarify the
+microscopic mechanism of carbon annihilation due to phosphorous treatment upon
+oxidation of silicon carbide (SiC). We identify the most stable form of the
+phosphorus (P) in the oxide as the four-fold coordinated with the dangling PO
+unit and find that the unit attracts carbon ejected from the interface, thus
+operating as a carbon absorber. This finding provides a microscopic reasoning
+for the first time for the promotion of the oxidation reaction on one hand and
+the annihilation of the C-related defects at the interface on the other.
+Secondary ion mass spectrometry measurements are also performed and the
+obtained carbon profile corroborates the theoretical finding above.",1703.08063v1
+2018-04-26,Role of substrate on interaction of water molecules with graphene oxide and reduced graphene oxide,"We study local electronic properties of graphene oxide (GO) and reduced
+graphene oxide (RGO) on metallic (Pt) and insulating (Si3N4) substrates in
+controlled humidity environment. We demonstrate that the supporting substrate
+plays a crucial role in interaction of these materials with water, with Pt
+making both GO and RGO insensitive to humidity variations and change in
+environment. On the other hand, in the case of Si3N4 substrate a significant
+difference between GO and RGO with respect to humidity variations is
+demonstrated, indicating complete water coverage at ~60% R.H for RGO and ~30%
+R.H. for GO. Irrespective of the substrate, both GO and RGO demonstrate
+relative independence of their electronic properties on the material thickness,
+with similar trends observed for 1, 2 and 3 layers when subject to humidity
+variations. This indicates a relatively minor role of material thickness in
+GO-based humidity sensors.",1804.09984v1
+2018-11-10,Atomic process of oxidative etching in monolayer molybdenum disulfide,"The microscopic process of oxidative etching of two-dimensional molybdenum
+disulfide (2D MoS2) at an atomic scale is investigated using a correlative
+TEM-etching study. MoS2 flakes on graphene TEM grids are precisely tracked and
+characterized by TEM before and after the oxidative etching. This allows us to
+determine the structural change with an atomic resolution on the edges of the
+domains, of well-oriented triangular pits and along the grain boundaries. We
+observe that the etching mostly starts from the open edges, grain boundaries
+and pre-existing atomic defects. A zigzag Mo edge is assigned as the dominant
+termination of the triangular pits, and profound terraces and grooves are
+observed on the etched edges. Based on the statistical TEM analysis, we reveal
+possible routes for the kinetics of the oxidative etching in 2D MoS2, which
+should also be applicable for other 2D transition metal dichalcogenide
+materials like MoSe2 and WS2.",1811.04242v1
+2018-11-04,"Characterization of Phosphorite Bearing Uraniferous Anomalies of Bijawar region, Madhya Pradesh, India","The uranium containing phosphatic shale sub surface samples collected from
+Bijawar region Madhya Pradesh (M.P.), India as a part of the uranium
+exploration programme of the Atomic Minerals Directorate for Exploration and
+Research (AMD), Department of Atomic Energy (DAE) were characterized by a
+variety of molecular spectroscopic techniques such as photoluminiscence (PL),
+time resolved photoluminiscence spectroscopy (TRPL), X-ray absorption near edge
+spectroscopy (XANES), Raman spectroscopy and structural techniques such as
+X-ray diffraction (XRD) to identify the oxidation state, physical and chemical
+form of uranium in this region. Oxidation state analysis by fluorescence
+spectroscopy revealed majority of the samples in U(VI) oxidation state. The
+most abundant form of uranium was identified as uranate (UO66-) ion, as a
+substituent of Ca++ in Ca5(PO4)3F, Flourapatite (FAP). Two uranium species in
+U(VI) and U(IV) state; (UO2)2+ adsorbed on silica and uranium oxide species
+(UO2) were also identified. The study provided baseline information on the
+speciation of uranium in Bijawar region.",1811.05541v1
+2018-11-25,Identification of two-dimensional $FeO_2$ termination of hematite $α-Fe_2O_3(0001)$ surface,"Iron oxides are among the most abundant compounds on Earth and have
+consequently been studied and used extensively in industrial processes. Despite
+these efforts, concrete understanding of some of their surface phase structures
+has remained elusive, in particular the oxidized ${\alpha}-Fe_2O_3(0001)$
+hematite surface. We detail an optimized recipe to produce this phase over the
+entire hematite surface and study the geometrical parameters and composition of
+its complex structure by means of atomically resolved microscopy, electron
+diffraction and surface-sensitive spectroscopies. We conclude that the oxidized
+${\alpha}-Fe_2O_3(0001)$ surface is terminated by a two-dimensional iron oxide
+with structure, lattice parameters, and orientation different from the bulk
+substrate. Using total-energy density functional theory for simulation of a
+large-scale atomic model, we identify the structure of the surface layer as
+antiferromagnetic, conductive $1T-FeO_2$ attached on half-metal terminated
+bulk. The model succeeds in reproducing the characteristic modulations observed
+in the atomically resolved images and electron diffraction patterns.",1811.09996v1
+2018-11-26,Synthesis of Oxidation-Resistant Electrochemical-Active Copper Nanowires Using Phenylenediamine Isomers,"Phenylenediamine (PDA) was chosen as a coordinating, reducing, and capping
+agent to effectively direct growth and protect against oxidation of Cu
+nanowires (Cu NWs) in an aqueous solution. PDA was found to reduce Cu (II) to
+Cu (I) at room temperature, and stabilize the resulting Cu (I) by forming a
+coordination complex. The presence of a stable Cu (I) complex is the key step
+in the synthesis of Cu NWs under mild conditions. Different PDA isomers lead to
+different growth paths of forming Cu NWs. Both pPDA and mPDA-synthesized Cu NWs
+were covered with a thin layer of polyphenylenediamine and show excellent
+anti-oxidation properties, even in the presence of water. The usefulness of the
+present and electrochemical active Cu NWs for a variety of nanotechnology
+applications is discussed.",1811.10510v1
+2018-11-27,Highly enhanced field emission current density of copper oxide coated vertically aligned carbon nanotubes: Role of interface and electronic structure,"We report the field emission (FE) properties of Cu coated vertically aligned
+carbon nanotubes (VACNTs) before and after oxidation. The current density was
+found to be the maximum (20 mA/cm$^2$) for 3 nm thick Cu coated VACNTs after
+oxidation. The variation in conventionally monitored parameters like work
+function and field enhancement factor does not explain the experimentally
+determined FE current density. A critical analysis of the electronic structure
+reveals the importance of presence of Cu$_2$O at the interface of CuO and
+VACNTs, which in turn controls the current density of these films. The highly
+enhanced FE current density of 3 nm Cu coated VACNTs after oxidation suggests
+its potential as a next generation electron source in vacuum microelectronic
+devices.",1811.10951v1
+2019-05-20,Improved Description of Perovskite Oxide Crystal Structure and Electronic Properties using Self-Consistent Hubbard $U$ Corrections from ACBN0,"The wide variety of complex physical behavior exhibited in transition metal
+oxides, particularly the perovskites A$B$O$_3$, makes them a material family of
+interest in many research areas, but the drastically different electronic
+structures possible in these oxides raises challenges in describing them
+accurately within density functional theory (DFT) and related methods. Here we
+evaluate the ability of the ACBN0, a recently developed first-principles
+approach to computing the Hubbard $U$ correction self-consistently, to describe
+the structural and electronic properties of the first-row transition metal
+perovskites with $\left(B=\textrm{V}-\textrm{Ni} \right)$. ACBN0 performs
+competitively with hybrid functional approaches such as the
+Heyd-Scuseria-Ernzerhof (HSE) functional even when they are optimized
+empirically, at a fraction of the computational cost. ACBN0 also describes both
+the structure and band gap of the oxides more accurately than a conventional
+Hubbard $U$ correction performed by using $U$ values taken from the literature.",1905.08328v3
+2020-07-01,Colossal Seebeck coefficient in Aurivillius Phase-Perovskite Oxide Composite,"We propose an inexpensive scalable approach for achieving extremely high
+values of Seebeck coefficient ($\alpha$) by exploiting the natural superlattice
+structure in Aurivillius phase oxides. In particular, we report an $\alpha
+\approx $ 319\,mV/K at 300\,K in a composite of Aurivillius phase compound
+SrBi$_4$Ti$_4$O$_{15}$ (as a matrix) and a perovskite phase material (e.g.,
+La$_{0.7}$Sr$_{0.3}$MnO$_3$ or, La$_{0.7}$Sr$_{0.3}$CoO$_3$ as filler). Such a
+colossal value of $\alpha$ can be attributed to contributions from the enhanced
+density of states due to the effective low dimensional character of Bi$_2$O$_2$
+layer. The corresponding thermal conductivity ($\kappa$) and the electrical
+conductivity ($\sigma$) lies in the range 0.7 - 1.25 W/m-K and 10 - 100
+$\mu$S/m, respectively at 300\,K. Attributed to the high $\alpha$ values, such
+oxide composites can be used as thermopile sensors and highly sensitive
+bolometric applications. We anticipate that the demonstration of colossal
+$\alpha$ in oxide composites using a simple synthesis strategy also sets the
+stage for future material innovations for high temperature thermoelectric
+applications.",2007.00632v2
+2020-07-28,A Novel Compact Si-B-N Barrier on Mg-Li Alloys via Plasma Treatment,"Mg-Li alloys have attracted much attention due to their superior properties.
+However, it is a great challenge to improve their inferior oxidation and
+corrosion resistance. We report a novel Si-B-N ceramic film deposited on the
+Mg-9.6Li alloy surface as an effective barrier against oxidation and corrosion.
+The films were deposited by using plasma enhanced chemical vapor deposition
+from a N2-B2H6-SiH4 gas mixtures, showing compact structure and adhesive
+attachment to the alloy surface. The barrier revealed excellent protection
+against oxidation in humid air for 500 days, and no observable changes were
+found in immersion test of the 3.5 wt.% NaCl solution for 10 min. The superior
+oxidation and corrosion resistance are attributed to the excellent material
+property of Si-B-N coatings with compact structure via plasma treatment.
+Moreover, it is found that moderate proportion of B_2 H_6 in the source gas
+mixture is beneficial to the protection of alloys, where the hydrogen release
+reaction nearly disappeared and no bubbles were generated on the surface in the
+immersion test.",2007.14170v1
+2013-08-10,A large energy-gap oxide topological insulator based on the superconductor BaBiO3,"Mixed-valent perovskite oxides based on BaBiO3 (BBO) are, like cuperates,
+well-known high-Tc superconductors. Recent ab inito calculations have assigned
+the high-Tc superconductivity to a correlation-enhanced electron--phonon
+coupling mechanism, stimulating the prediction and synthesis of new
+superconductor candidates among mixed-valent thallium perovskites. Existing
+superconductivity has meant that research has mainly focused on hole-doped
+compounds, leaving electron-doped compounds relatively unexplored. Here we
+demonstrate through ab inito calculations that BBO emerges as a topological
+insulator (TI) in the electron-doped region, where the spin-orbit coupling
+(SOC) effect is significant. BBO exhibits the largest topological energy gap of
+0.7 eV among currently known TI materials, inside which Dirac-type topological
+surface states (TSSs) exit. As the first oxide TI, BBO is naturally stable
+against surface oxidization and degrading, different from chalcoginide TIs. An
+extra advantage of BBO lies in its ability to serve an interface between the
+TSSs and the superconductor for the realization of Majorana Fermions.",1308.2303v1
+2013-08-24,Gold and Methane: A Noble Combination for Delicate Oxidation,"The ability to partially oxidize methane at low temperatures and pressures
+would have important environmental and economic applications. Although methane
+oxidation on gold nanoparticles has been observed experimentally, our density
+functional theory (DFT) calculations indicate neither CH4, CH3, nor H adsorb on
+a neutral gold nanoparticle. However, by positively charging gold
+nanoparticles, e.g. through charge transfer to the TiO2 substrate, CH4 binding
+increases while O2 binding remains relatively unchanged. We demonstrate that
+CH4 adsorption is via bonding with the metal s levels. This holds from small
+gold clusters (Au2) to large gold nanoparticles (Au201), and for all fcc
+transition metal dimers. These results provide the chemical understanding
+necessary to tune the catalytic activity of metal nanoparticles for the partial
+oxidation of methane under delicate conditions.",1308.5266v1
+2014-03-03,Methane Oxidation to Methanol without CO2 Emission: Catalysis by Atomic Negative Ions,"The catalytic activities of the atomic Y-, Ru-, At-, In-, Pd-, Ag-, Pt-, and
+Os- ions have been investigated theoretically using the atomic Au- ion as the
+benchmark for the selective partial oxidation of methane to methanol without
+CO2 emission. Dispersion-corrected density-functional theory has been used for
+the investigation. From the energy barrier calculations and the thermodynamics
+of the reactions, we conclude that the catalytic effect of the atomic Ag-, At-,
+Ru-, and Os- ions is higher than that of the atomic Au- ion catalysis of CH4
+conversion to methanol. By controlling the temperature around 290K (Os-), 300K
+(Ag-), 310K (At-), 320K (Ru-) and 325K (Au-) methane can be completely oxidized
+to methanol without the emission of CO2. We conclude by recommending the
+investigation of the catalytic activities of combinations of the above negative
+ions for significant enhancement of the selective partial oxidation of methane
+to methanol.",1403.0597v1
+2016-11-30,The Effects of Vacancy and Oxidation on Black Phosphorus Nanoresonators,"Black phosphorene is not stable at ambient conditions, so atomic defects and
+oxidation effects are unavoidable in black phosphorus samples in the
+experiment. The effects of these defects on the performance of the black
+phosphorus nanoresonators are still unclear. Here, we perform classical
+molecular dynamics to investigate the effects of the vacancy and oxidation on
+single-layer black phosphorus nanoresonators at different temperatures. We find
+that the vacancy causes strong reduction in the quality factor of the
+nanoresonators, while the oxidation has weaker effect on the nanoresonators.
+More specifically, a 2% concentration of randomly distributed single vacancies
+is able to reduce the quality factor by about 80% and 40% at 4.2K and 50K,
+respectively. We also find that the quality factor of the nanoresonator is not
+sensitive to the distribution pattern of the vacancy defects.",1611.10048v1
+2017-01-20,Oxygen reduction mechanisms in nanostructured La0.8Sr0.2MnO3 cathodes for Solid Oxide Fuel Cells,"In this work we outline the mechanisms contributing to the oxygen reduction
+reaction in nanostructured cathodes of La0.8Sr0.2MnO3 (LSM) for Solid Oxide
+Fuel Cells (SOFC). These cathodes, developed from LSM nanostructured tubes, can
+be used at lower temperatures compared to microstructured ones, and this is a
+crucial fact to avoid the degradation of the fuel cell components. This
+reduction of the operating temperatures stems mainly from two factors: i) the
+appearance of significant oxide ion diffusion through the cathode material in
+which the nanostructure plays a key role and ii) an optimized gas phase
+diffusion of oxygen through the porous structure of the cathode, which becomes
+negligible. A detailed analysis of our Electrochemical Impedance Spectroscopy
+supported by first principles calculations point towards an improved overall
+cathodic performance driven by a fast transport of oxide ions through the
+cathode surface.",1701.05928v1
+2017-01-23,In situ X-ray diffraction studies of graphite oxidation reaction indicating different exfoliation mechanism than ex site studies,"We offer a brief overview of the solvent-based graphene production and
+summarize the current knowledge on the formation mechanism of graphite oxide
+that proceeds via graphite intercalation compounds. In addition, the results of
+our in situ X-ray diffraction investigation into this process are presented,
+discussed and contrasted to the findings by other authors, who employed the
+same oxidation protocol but examined the samples by ex situ X-ray diffraction.
+Our results suggest that, contrary to the numerous reports by other authors, no
+strong crystalline order, unique to graphite intercalation compounds as well as
+graphite oxide, develops if they remain in concentrated acid. Furthermore, it
+also appears that, depending on the concentration, sulfuric acid molecules
+significantly weaken graphene-graphene interactions in graphite. Consequently,
+concentrated sulfuric acid may be a good solvent for graphene dispersions, if
+only there is sufficient energy input to separate the layers of graphene.",1701.06493v1
+2018-05-13,In-situ angle-resolved photoemission spectroscopy of copper-oxide thin films synthesized by molecular beam epitaxy,"Angle-resolved photoemission spectroscopy (ARPES) is the key
+momentum-resolved technique for direct probing of the electronic structure of a
+material. However, since it is very surface-sensitive, it has been applied to a
+relatively small set of complex oxides that can be easily cleaved in ultra-high
+vacuum. Here we describe a new multi-module system at Brookhaven National
+Laboratory (BNL) in which an oxide molecular beam epitaxy (OMBE) is
+interconnected with an ARPES and a spectroscopic-imaging scanning tunneling
+microscopy (SI-STM) module. This new capability largely expands the range of
+complex-oxide materials and artificial heterostructures accessible to these two
+most powerful and complementary techniques for studies of electronic structure
+of materials. We also present the first experimental results obtained using
+this system - the ARPES studies of electronic band structure of a
+La$_{2-x}$Sr$_x$CuO$_4$ (LSCO) thin film grown by OMBE.",1805.04811v1
+2018-05-23,High-throughput study of the static dielectric constant at high temperatures in oxide and fluoride cubic perovskites,"Using finite-temperature phonon calculations and the Lyddane-Sachs-Teller
+relations, we calculate ab initio the static dielectric constants of 78
+semiconducting oxides and fluorides with cubic perovskite structures at 1000 K.
+We first compare our method with experimental measurements, and we find that it
+succeeds in describing the temperature dependence and the relative ordering of
+the static dielectric constant $\epsilon_{DC}$ in the series of oxides
+BaTiO$_{3}$, SrTiO$_{3}$, KTaO$_{3}$. We show that the effects of anharmonicity
+on the ion-clamped dielectric constant, on Born charges, and on phonon
+lifetimes, can be neglected in the framework of our high-throughput study.
+Based on the high-temperature phonon spectra, we find that the dispersion of
+$\epsilon_{DC}$ is one order of magnitude larger amongst oxides than fluorides
+at 1000 K. We display the correlograms of the dielectric constants with simple
+structural descriptors, and we point out that $\epsilon_{DC}$ is actually well
+correlated with the infinite-frequency dielectric constant $\epsilon_{\infty}$,
+even in those materials with phase transitions in which $\epsilon_{DC}$ is
+strongly temperature-dependent.",1805.09199v2
+2018-05-25,Evidence for Incipient Ferroelectricity in YCrO3,"Cubic structure is one of the most commonly found structures for oxides at
+high temperature. As the temperature is lowered only a handful of these oxides
+exhibit ferroelectricity which is rather surprising. In this paper, we use the
+example of YCrO3 (YCO), an incipient ferroelectric material to show that in
+most oxides there are two competing phenomenon -onset of ferroelectricity due
+to rotation of CrO6 octahedra and displacement of Y atom leading to suppression
+of ferroelectricity. This competition reveals that while the octahedral
+rotations favor a lower symmetry state, the Y atom displacement opposes it
+leaving YCO to exhibit only an incipient ferroelectric state. These results
+while being in agreement with the earlier theoretical predictions can also help
+suggest a pathway to a more stable ferroelectric state in these oxides by using
+a larger cationic substitution at the Y site.",1805.10077v1
+2008-07-16,Cleaving-temperature dependence of layered-oxide surfaces,"The surfaces generated by cleaving non-polar, two-dimensional oxides are
+often considered to be perfect or ideal. However, single particle
+spectroscopies on Sr2RuO4, an archetypal non-polar two dimensional oxide, show
+significant cleavage temperature dependence. We demonstrate that this is not a
+consequence of the intrinsic characteristics of the surface: lattice parameters
+and symmetries, step heights, atom positions, or density of states. Instead, we
+find a marked increase in the density of defects at the mesoscopic scale with
+increased cleave temperature. The potential generality of these defects to
+oxide surfaces may have broad consequences to interfacial control and the
+interpretation of surface sensitive measurements.",0807.2672v1
+2011-11-22,Multilayer Edge Molecular Devices Based on Plasma Oxidation of Photolithographically Defined Bottom Metal Electrode,"A multilayer edge molecular electronics device (MEMED), which utilize the two
+metal electrodes of a metal-insulator-metal tunnel junction as the two
+electrical leads to molecular channels, can overcome the long standing
+fabrication challenges for developing futuristic molecular devices. However,
+producing ultrathin insulator is the most challenging step in MEMED
+fabrication. A simplified molecular device approach was developed by avoiding
+the need of depositing a new materiel on the bottom electrode for growing
+ultrathin insulator. This paper discuss the approach for MEMED's insulator
+growth by one-step oxidation of a tantalum (Ta) bottom electrode, in the
+pholithographically defined region; i.e. ultrathin tantalum oxide (TaOx)
+insulator was grown by oxidizing bottom metal electrode itself. Organometallic
+molecular clusters (OMCs) were bridged across 1-3 nm TaOx along the perimeter
+of a tunnel junction to establish the highly efficient molecular conduction
+channels. OMC transformed the asymmetric transport profile of TaOx based tunnel
+junction into symmetric one. A TaOx based tunnel junction with top
+ferromagnetic (NiFe) electrode exhibited the transient current suppression by
+several orders. Further studies will be needed to strengthen the current
+suppression phenomenon, and to realize the full potential of TaOx based
+multilayer edge molecular spintronics devices.",1111.5087v1
+2012-01-09,Resonant charge transfer at dielectric surfaces,"We report on the theoretical description of secondary electron emission due
+to resonant charge transfer occurring during the collision of metastable
+nitrogen molecules with dielectric surfaces. The emission is described as a two
+step process consisting of electron capture to form an intermediate shape
+resonance and subsequent electron emission by decay of this ion, either due to
+its natural life time or its interaction with the surface. The electron capture
+is modeled using the Keldysh Green's function technique and the negative ion
+decay is described by a combination of the Keldysh technique and a rate
+equation approach. We find the resonant capture of electrons to be very
+efficient and the natural decay to be clearly dominating over the
+surface-induced decay. Secondary electron emission coefficients are calculated
+for aluminum oxide, magnesium oxide, silicon oxide, and diamond at several
+kinetic energies of the projectile. With the exception of magnesium oxide the
+coefficients turn out to be of the order of 0.1 over the whole range of kinetic
+energies. This rather large value is a direct consequence of the shape
+resonance acting as a relay state for electron emission.",1201.1724v1
+2012-04-20,Dynamic and Static Transmission Electron Microscopy Studies on Structural Evaluation of Au nano islands on Si (100) Surface,"Transmission electron microscopy (TEM) study on morphological changes in gold
+nanostructures deposited on Si (100) upon annealing under different vacuum
+conditions has been reported. Au thin films of thickness ~2.0 nm were deposited
+under high vacuum condition (with the native oxide at the interface of Au and
+Si) using thermal evaporation. In-situ, high temperature (from room temperature
+(RT) to 850\degreeC) real time TEM measurements showed the evaluation of gold
+nanoparticles into rectangular/square shaped gold silicide structures. This has
+been attributed to selective thermal decomposition of native oxide layer.
+Ex-situ annealing in low vacuum (10-2 mbar) at 850\degreeC showed no growth of
+nano-gold silicide structures. Under low vacuum annealing conditions, the
+creation of oxide could be dominating compared to the decomposition of oxide
+layers resulting in the formation of barrier layer between Au and Si.",1204.4618v1
+2013-09-24,Oxidation of GaN: An ab initio thermodynamic approach,"GaN is a wide-bandgap semiconductor used in high-efficiency LEDs and solar
+cells. The solid is produced industrially at high chemical purities by
+deposition from a vapour phase, and oxygen may be included at this stage.
+Oxidation represents a potential path for tuning its properties without
+introducing more exotic elements or extreme processing conditions. In this
+work, ab initio computational methods are used to examine the energy potentials
+and electronic properties of different extents of oxidation in GaN. Solid-state
+vibrational properties of Ga, GaN, Ga2O3 and a single substitutional oxygen
+defect have been studied using the harmonic approximation with supercells. A
+thermodynamic model is outlined which combines the results of ab initio
+calculations with data from experimental literature. This model allows free
+energies to be predicted for arbitrary reaction conditions within a wide
+process envelope. It is shown that complete oxidation is favourable for all
+industrially-relevant conditions, while the formation of defects can be opposed
+by the use of high temperatures and a high N2:O2 ratio.",1309.6232v1
+2015-12-25,Transformation of germanium to fluogermanates,"The surface of a single crystal Germanium wafer was transformed to crystals
+of germanium fluorides and oxides upon exposure to a vapor of HF and HNO3
+chemical mixture. Structure analysis indicate that the transformation results
+in a germanate polycrystalline layer consisting of germanium oxide and ammonium
+fluogermanate with a preferential crystal growth orientation in <101>
+direction. Local vibrational mode analysis confirms the presence of N-H and
+Ge-F vibrational modes in addition to Ge-O stretching modes. Energy dispersive
+studies reveal the presence of hexagonal {\alpha}-phase GeO2 crystal clusters
+and ammonium fluogermanates around these clusters in addition to a surface
+oxide layer. Electronic band structure as probed by ellipsometry has been
+associated with the germanium oxide crystals and disorder induced band tailing
+effects at the interface of the germanate layer and the bulk Ge wafer. The acid
+vapor exposure causes Ge surface to emit a yellow photoluminescence at room
+temperature.",1512.08001v1
+2015-12-30,Thermal radiative near field transport between vanadium dioxide and silicon oxide across the metal insulator transition,"The thermal radiative near field transport between vanadium dioxide and
+silicon oxide at submicron distances is expected to exhibit a strong dependence
+on the state of vanadium dioxide which undergoes a metal-insulator transition
+near room temperature. We report the measurement of near field thermal
+transport between a heated silicon oxide micro-sphere and a vanadium dioxide
+thin film on a titanium oxide (rutile) substrate. The temperatures of the 15 nm
+vanadium dioxide thin film varied to be below and above the
+metal-insulator-transition, the sphere temperatures were varied in a range
+between 100 and 200 Celsius. The measurements were performed using a
+vacuum-based scanning thermal microscope with a cantilevered resistive thermal
+sensor. We observe a thermal conductivity per unit area between the sphere and
+the film with a distance dependence following a power law trend and a
+conductance contrast larger than 2 for the two different phase states of the
+film.",1512.09050v2
+2016-05-24,First-principles Modelling of SrTiO3 based Oxides for Thermoelectric Applications,"Using first-principles electronic structure calculations, we studied the
+electronic and thermoelectric properties of SrTiO3 based oxide materials and
+their nanostructures identifying those nanostructures which possess highly
+anisotropic electronic bands. We showed recently that highly anisotropic
+flat-and-dispersive bands can maximize the thermoelectric power factor, and at
+the same time they can produce low dimensional electronic transport in bulk
+semiconductors. Although most of the considered nanostructures show such highly
+anisotropic bands, their predicted thermoelectric performance is not improved
+over that of SrTiO3. Besides highly anisotropic character, we emphasize the
+importance of the large weights of electronic states participating in transport
+and the small effective mass of charge carriers along the transport direction.
+These requirements may be better achieved in binary transition metal oxides
+than in ABO3 perovskite oxide materials.",1605.07387v1
+2016-05-27,Hydrostatic pressure response of an oxide two-dimensional electron system,"Two-dimensional electron systems with fascinating properties exist in
+multilayers of standard semiconductors, on helium surfaces, and in oxides.
+Compared to the two-dimensional (2D) electron gases of semiconductors, the 2D
+electron systems in oxides are typically more strongly correlated and more
+sensitive to the microscopic structure of the hosting lattice. This sensitivity
+suggests that the oxide 2D systems are highly tunable by hydrostatic pressure.
+Here we explore the effects of hydrostatic pressure on the well-characterized
+2D electron system formed at LaAlO$_{3}$ -SrTiO$_{3}$ interfaces[1] and measure
+a pronounced, unexpected response. Pressure of $\sim$2 GPa reversibly doubles
+the 2D carrier density $n_{s}$ at 4 K. Along with the increase of $n_{s}$, the
+conductivity and mobility are reduced under pressure. First-principles pressure
+simulations reveal the same behavior of the carrier density and suggest a
+possible mechanism of the mobility reduction, based on the dielectric
+properties of both materials and their variation under external pressure.",1605.08528v1
+2016-12-08,Superconductivity in higher titanium oxides,"Recent renewal of the highest transition temperature in a conventional
+superconductor of the sulfer hydride attracts much attention to exploring
+simple compounds with the lighter elements, situated in unconventional
+conditions. We report the discovery of superconductivity in simple oxides of
+Ti4O7 and g-Ti3O5 in a thin-film form having deliberately tuned epitaxial
+structures and off-stoichiometry. These higher titanium oxides join in a class
+of simple-oxide superconductors, and g-Ti3O5 now holds the highest
+superconducting transition temperature of 7.1 kelvin among them. The mechanism
+behind the superconductivity is discussed on the basis of electrical
+measurements and theoretical predictions. We conclude that superconductivity
+arises from unstabilized bipolaronic insulating states.",1612.02502v1
+2016-12-12,ARPES Studies of Two-Dimensional Electron Gases at Transition Metal Oxide Surfaces,"High mobility two-dimensional electron gases (2DEGs) underpin today's silicon
+based devices and are of fundamental importance for the emerging field of oxide
+electronics. Such 2DEGs are usually created by engineering band offsets and
+charge transfer at heterointerfaces. However, in 2011 it was shown that highly
+itinerant 2DEGs can also be induced at bare surfaces of different transition
+metal oxides where they are far more accessible to high resolution angle
+resolved photoemission (ARPES) experiments. Here we review work from this
+nascent field which has led to a systematic understanding of the subband
+structure arising from quantum confinement of highly anisotropic transition
+metal d-states along different crystallographic directions. We further discuss
+the role of different surface preparations and the origin of surface 2DEGs, the
+understanding of which has permitted control over 2DEG carrier densities.
+Finally, we discuss signatures of strong many-body interactions and how
+spectroscopic data from surface 2DEGs may be related to the transport
+properties of interface 2DEGs in the same host materials.",1612.03571v1
+2016-12-20,Oxidation dynamics of ultrathin GaSe probed through Raman spectroscopy,"Gallium selenide (GaSe) is a 2D material with a thickness-dependent gap,
+strong non-linear optical coefficients and uncommon interband optical selection
+rules, making it interesting for optoelectronic and spintronic applications. In
+this work, we monitor the oxidation dynamics of GaSe with thicknesses ranging
+from 10 to 200 nm using Raman spectroscopy. In ambient temperature and humidity
+conditions, the intensity of all Raman modes and the luminescence decrease
+rapidly with moderate exposure to above-gap illumination. Concurrently, several
+oxidation products appear in the Raman spectra: Ga$_2$Se$_3$, Ga$_2$O$_3$ and
+amorphous and crystalline selenium. We find that no safe measurement power
+exists for optical measurements on ultrathin GaSe in ambient conditions. We
+demonstrate that the simultaneous presence of oxygen, humidity, and above-gap
+illumination is required to activate this photo-oxidation process, which is
+attributed to the transfer of photo-generated charge carriers towards aqueous
+oxygen at the sample surface, generating highly reactive superoxide anions that
+rapidly degrade the sample and quench the optical response of the material.",1612.06907v3
+2016-12-21,Pure spin current transport in gallium doped zinc oxide,"We study the flow of a pure spin current through zinc oxide by measuring the
+spin Hall magnetoresistance (SMR) in thin film trilayer samples consisting of
+bismuth-substituted yttrium iron garnet (Bi:YIG), gallium-doped zinc oxide
+(Ga:ZnO), and platinum. We investigate the dependence of the SMR magnitude on
+the thickness of the Ga:ZnO interlayer and compare to a Bi:YIG/Pt bilayer. We
+find that the SMR magnitude is reduced by almost one order of magnitude upon
+inserting a Ga:ZnO interlayer, and continuously decreases with increasing
+interlayer thickness. Nevertheless, the SMR stays finite even for a
+$12\;\mathrm{nm}$ thick Ga:ZnO interlayer. These results show that a pure spin
+current indeed can propagate through a several nm-thick degenerately doped zinc
+oxide layer. We also observe differences in both the temperature and the field
+dependence of the SMR when comparing tri- and bilayers. Finally, we compare our
+data to predictions of a model based on spin diffusion. This shows that
+interface resistances play a crucial role for the SMR magnitude in these
+trilayer structures.",1612.07239v1
+2017-06-09,Effect of oxygen plasma on nanomechanical silicon nitride resonators,"Precise control of tensile stress and intrinsic damping is crucial for the
+optimal design of nanomechanical systems for sensor applications and quantum
+optomechanics in particular. In this letter we study the in uence of oxygen
+plasma on the tensile stress and intrinsic damping of nanomechanical silicon
+nitride resonators. Oxygen plasma treatments are common steps in micro and
+nanofabrication. We show that oxygen plasma of only a few minutes oxidizes the
+silicon nitride surface, creating several nanometer thick silicon dioxide
+layers with a compressive stress of 1.30(16)GPa. Such oxide layers can cause a
+reduction of the e ective tensile stress of a 50 nm thick stoichiometric
+silicon nitride membrane by almost 50%. Additionally, intrinsic damping
+linearly increases with the silicon dioxide lm thickness. An oxide layer of
+1.5nm grown in just 10s in a 50W oxygen plasma almost doubled the intrinsic
+damping. The oxide surface layer can be e ciently removed in bu ered HF.",1706.02957v1
+2017-07-01,Hydration Peculiarities of Graphene Oxides with Multiple Oxidation Degrees,"Hydration properties of graphene oxide (GO) are essential for most of its
+potential applications. In this work, we employ atomistic molecular dynamics
+simulations to investigate seven GO compositions with different levels of
+oxygenation. Two atomic charge models for GO are compared: (1) sp2 carbons are
+purely Lennard-Jones sites; (2) sp2 carbon charges are consistent with the
+CHELPG scheme. Structural properties were found to depend insignificantly on
+the charge model, whereas thermodynamics appeared very sensitive. In
+particular, the simplified model provides systematically stronger GO/water
+coupling, as compared to the more accurate model. For all GO compositions,
+hydration free energies are in the range -5 to -45 kJ mol-1 indicating that
+hydration is thermodynamically favorable even for modest oxidation degrees,
+thus differing drastically from the case of pristine graphene and graphite. The
+results and discussion presented hereby provide a physical background for
+modern applications of GO, e.g. in electrodes of supercapacitors and inhibitors
+in processes involving biological molecules.",1707.00126v2
+2017-07-21,The Efficacy of Fiction or More on the Charge State of Ti in TiO2 and Formal Oxidation States,We argue that Ti4+ is not a realistic description of Ti in TiO2.,1707.06851v1
+2017-10-23,Tuning the two-dimensional electron liquid at oxide interfaces by buffer-layer-engineered redox reactions,"Polar discontinuities and redox reactions provide alternative paths to create
+two-dimensional electron liquids (2DELs) at oxide interfaces. Herein, we report
+high mobility 2DELs at interfaces involving SrTiO3 (STO) achieved using polar
+La7/8Sr1/8MnO3 (LSMO) buffer layers to manipulate both polarities and redox
+reactions from disordered overlayers grown at room temperature. Using resonant
+x-ray reflectometry experiments, we quantify redox reactions from oxide
+overlayers on STO as well as polarity induced electronic reconstruction at
+epitaxial LSMO/STO interfaces. The analysis reveals how these effects can be
+combined in a STO/LSMO/disordered film trilayer system to yield high mobility
+modulation doped 2DELs, where the buffer layer undergoes a partial
+transformation from perovskite to brownmillerite structure. This uncovered
+interplay between polar discontinuities and redox reactions via buffer layers
+provides a new approach for the design of functional oxide interfaces.",1710.08121v1
+2017-10-26,Super nucleation and orientation of poly (butylene terephthalate) crystals in nanocomposites containing highly reduced graphene oxide,"The ring opening polymerization of cyclic butylene terephthalate into poly
+(butylene terephthalate) (pCBT) in the presence of reduced graphene oxide (RGO)
+is an effective method for the preparation of polymer nanocomposites. The
+inclusion of RGO nanoflakes dramatically affects the crystallization of pCBT,
+shifting crystallization peak temperature to higher temperatures and, overall,
+increasing the crystallization rate. This was due to a super nucleating effect
+caused by RGO, which is maximized by highly reduced graphene oxide.
+Furthermore, combined analyses by differential scanning calorimetry (DSC)
+experiments and wide angle X-ray diffraction (WAXS) showed the formation of a
+thick {\alpha}-crystalline form pCBT lamellae with a melting point of ~250
+{\deg}C, close to the equilibrium melting temperature of pCBT. WAXS also
+demonstrated the pair orientation of pCBT crystals with RGO nanoflakes,
+indicating a strong interfacial interaction between the aromatic rings of pCBT
+and RGO planes, especially with highly reduced graphene oxide. Such surface
+self-organization of the polymer onto the RGO nanoflakes may be exploited for
+the enhancement of interfacial properties in their polymer nanocomposites.",1710.09658v1
+2017-12-08,Imaging Pulsed Laser Deposition oxide growth by in-situ Atomic Force Microscopy,"To visualize the topography of thin oxide films during growth, thereby
+enabling to study its growth behavior quasi real-time, we have designed and
+integrated an atomic force microscope (AFM) in a pulsed laser deposition (PLD)
+vacuum setup. The AFM scanner and PLD target are integrated in a single support
+frame, combined with a fast sample transfer method, such that in-situ
+microscopy can be utilized after subsequent deposition pulses. The in-situ
+microscope can be operated from room temperature (RT) up to 700$^\circ$C and at
+(process) pressures ranging from the vacuum base pressure of 10$^{-6}$ mbar up
+to 1 mbar, typical PLD conditions for the growth of oxide films. The
+performance of this instrument is demonstrated by resolving unit cell height
+surface steps and surface topography under typical oxide PLD growth conditions.",1712.02988v1
+2017-12-13,Atomic-scale mechanisms of defect- and light-induced oxidation and degradation of InSe,"Layered indium selenide (InSe), a new two-dimensional (2D) material with a
+hexagonal structure and semiconducting characteristic, is gaining increasing
+attention owing to its intriguing electronic properties. Here, by using
+first-principles calculations, we reveal that perfect InSe possesses a high
+chemical stability against oxidation, superior to MoS2. However, the presence
+of intrinsic Se vacancy (VSe) and light illumination can markedly affect the
+surface activity. In particular, the excess electrons associated with the
+exposed In atoms at the VSe site under illumination are able to remarkably
+reduce the dissociation barrier of O2 to ~0.2 eV. Moreover, at ambient
+conditions, the splitting of O2 enables the formation of substitutional
+(apical) oxygen atomic species, which further cause the trapping and subsequent
+rapid splitting of H2O molecules and ultimately the formation of hydroxyl
+groups. Our findings uncover the causes and underlying mechanisms of InSe
+surface degradation via the defect-photo promoted oxidations. Such results will
+be beneficial in developing strategies for the storage of InSe material and its
+applications for surface passivation with boron nitride, graphene or In-based
+oxide layers.",1712.04662v1
+2018-09-28,Strong phonon anharmonicity and low thermal conductivity of monolayer tin oxides driven by lone-pair electrons,"Motivated by the excellent electronic and optoelectronic properties of
+two-dimensional (2D) tin oxides, we systematically investigated the thermal
+conductivity of monolayer SnO and SnO2by the first-principles calculations. The
+room-temperature thermal conductivity of monolayer SnO and SnO2reaches 9.6
+W/(mK) and 98.8 W/(mK), respectively. The size effect is much weaker for
+monolayer SnO than for monolayer SnO2, due to the coexistence of size dependent
+and independent component in the thermal conductivity of monolayer SnO. The
+large difference between the thermal conductivity of 2D tin oxides can be
+attributed to the small phonon group velocity and strong anharmonicity strength
+of monolayer SnO. Further electronic structure analysis reveals that the
+existence of lone-pair Sn-5s electrons is the key factor for the small \k{appa}
+of monolayer SnO. These results provide a guide for the manipulation of thermal
+transport in the electronic or thermoelectric devices based on 2D tin oxides.",1809.11124v2
+2018-10-18,Coating of Aluminum Alloys by Micro Arc Oxidation in Nitrate Salt,"Plasma electrolytic oxidation (PEO) is a process for obtaining oxide coatings
+on valve metals. Mostly PEO is done in an aqueous solution electrolyte which
+limits the size of treated parts due to the system heating up. In presented
+work an alternative method of PEO processing applied in aluminum 1050 alloy in
+nitrate molten salt was investigated. The morphology, phase and chemical
+compositions, micro-hardness, and corrosion resistance were examined using. The
+obtained results showed that formed coating contains from two sub-layers, outer
+soft layer with the thickness of 4 micrometer and inner, denser layer with the
+thickness of 5 micrometer. The formed coating consists of corundum, {\gamma} -
+Al2O3, {\theta} - Al2O3 and is free of any contaminants originated from the
+electrolyte.",1810.08018v1
+2018-10-31,A polaron cloud of correlated electron states in ceria,"The electronic structure of cerium oxide is investigated here using a
+combination of ab initio one-electron theory and many-body physics, with
+emphasis on the nature of the 4f electron shell of cerium ions. We propose to
+use the hybridization function as a convenient measure for the degree of
+localization of the 4f shell of this material, and observe that changing the
+oxidation state is related to distinct changes in the hybridization between the
+4f shell and ligand states. The theory reveals that CeO$_2$ has essentially
+itinerant 4f states, and that in the least oxidized form of ceria, Ce$_2$O$_3$,
+the 4f states are almost (but not fully) localized. Most importantly, our model
+points to that diffusion of oxygen vacancies in cerium oxide may be seen as
+polaron hopping, involving a correlated 4f electron cloud, which is located
+primarily on Ce ions of atomic shells surrounding the vacancy.",1810.13211v1
+2019-06-15,Oxide layer thickness effects on the resistance switching characteristics of Ti/TiO2-NT/Au structure,"Self-ordered nanotubular titania TiO2-NT with outer tube diameter of 45 nm
+are synthesized using the anodic oxidation of titanium foil. Four sets of
+memristors with 100 ${\mu}m$ diameter based on Ti/TiO2-NT/Au sandwich
+structures with an oxide layer thickness of 80, 120, 160 and 200 nm are
+fabricated. Current-voltage (CV) characteristics for the obtained samples in
+the static and dynamic operation modes are studied. Resistance in high and low
+resistance states is estimated. Basing on the analysis of the CV
+characteristics in dynamic mode (> 14 000 switchings) a prospective of use for
+synthesized Ti/TiO2-NT/Au micromemristors with oxide layer thickness of 160 nm
+in non-volatile memory is shown.
+  Keywords: anodic titania, titanium dioxide nanotubes, nanotubular structure,
+memristor, resistive switching",1906.06555v1
+2019-07-16,In situ Auger electron spectroscopy of complex oxide surfaces grown by pulsed laser deposition,"The authors report in situ Auger electron spectroscopy (AES) of the surfaces
+of complex oxides thin films grown by pulsed laser deposition (PLD). The
+authors demonstrate the utility of the technique in studying chemical
+composition by collecting characteristic Auger spectra of elements from samples
+such as complex oxide thin films and single crystals as well as metal foils. In
+the case of thin films, AES studies can be performed with single unit cell
+precision by monitoring thickness during deposition with reflection high energy
+electron diffraction (RHEED). The authors address some of the challenges in
+achieving in situ and real time AES studies on complex oxide thin films grown
+by PLD. Sustained layer-by-layer PLD growth of a CaTiO3/LaMnO3 superlattice
+allows depth-resolved chemical composition analysis during the growth process.
+The evolution of the Auger spectra of the elements from individual layers were
+used to perform chemical analysis with monolayer-depth resolution.",1907.07272v1
+2020-02-05,Gate-controlled photo-oxidation of graphene for electronic structure modification,"Graphene is an ultrathin material, which allows us to control surface
+phenomena by means of field-effect gating. Among various surface phenomena,
+photo-oxidation is known to be a facile method to largely control the
+electronic structure of graphene. In this study, gate controllability of
+photo-oxidation of graphene is thoroughly examined using a
+field-effect-transistor configuration. The presence of water molecules enhances
+gate controllability, which can be explained using water-oxygen co-adsorption
+picture. In addition, the photo-oxidation reaction evolves from the edge and
+proceeds towards the center of the graphene channel, which can be understood by
+the fringing field effect. Semiconducting characteristics are successfully
+obtained by narrowing of the graphene channel, suggesting possible formation of
+a graphene nanoribbon under mild conditions, i.e., in air at room temperature.",2002.01694v1
+2020-04-14,Structural dynamics in thermal-treatment of amorphous indium-oxide films,"Thermally-treating amorphous indium-oxide films is used in various basic
+studies as a means of tuning the system disorder. In this process the
+resistance of a given sample decreases while its amorphous structure and
+chemical composition is preserved. The main effect of the process is an
+increase in the system density which in turn leads to improved interatomic
+overlap which is easily detected as improved conductivity. A similar effect has
+been observed in studies of other amorphous systems that were subjected to
+pressure. In the current work we show that the Raman spectra of amorphous
+indium-oxide change in response to thermal-treatment in a similar way as in
+pressure experiments performed on other disordered and amorphous systems. We
+present a study of how thermal-treatment changes the system dynamics by
+monitoring the resistance versus time of indium-oxide films following various
+stages of thermal-treatment. The time dependence of the sample resistance fits
+the stretched exponential law with parameters that change systematically with
+further annealing. Implication of these results to slow dynamics phenomena that
+are governed by the Kohlrausch's law are discussed.",2004.06322v1
+2020-04-14,Temperature overshoot as the cause of physical changes in resistive switching devices during electro-formation,"Resistive switching devices based on transition metal oxides require
+formation of a conductive filament in order for the device to be able to
+switch. Such filaments have been proposed to form by the reduction of the oxide
+due to application of the electric field, but this report seeks to rebut that
+interpretation. Frequently reported physical changes during electro-formation
+include delamination of electrodes, crystallization of functional oxide,
+intermixing of electrode and oxide materials, and extensive loss of oxygen
+presumably to the ambient. Here we show that most of these effects are not
+inherent to the formation and switching processes and instead are due to an
+experimental artifact: the discharge of parasitic capacitances in the forming
+circuit. Discharge of typical BNC cables can raise the temperature of the
+filament to between 2,000 and 5,000 K resulting in extensive physical changes.
+Discharge and associated effects mentioned above can be eliminated using an
+on-chip load element without affecting the ability to switch.",2004.06571v1
+2020-12-21,Frequency Response of Metal-Oxide Memristors,"Memristors have been at the forefront of nanoelectronics research for the
+last decade, offering a valuable component to reconfigurable computing. Their
+attributes have been studied extensively along with applications that leverage
+their state-dependent programmability in a static fashion. However, practical
+applications of memristor-based AC circuits have been rather sparse, with only
+a few examples found in the literature where their use is emulated at higher
+frequencies. In this work, we study the behavior of metal-oxide memristors
+under an AC perturbation in a range of frequencies, from 10^3 to 10^7 Hz.
+Metal-oxide memristors are found to behave as RC low-pass filters and they
+present a variable cut-off frequency when their state is switched, thus
+providing a window of reconfigurability when used as filters. We further study
+this behaviour across distinct material systems and we show that the usable
+reconfigurability window of the devices can be tailored to encompass specific
+frequency ranges by amending the devices' capacitance. This study extends
+current knowledge on metal-oxide memristors by characterising their frequency
+dependent characteristics, providing useful insights for their use in
+reconfigurable AC circuits.",2012.11519v1
+2021-01-18,Manipulating the anisotropic phase separation in strained VO2 epitaxial films by nanoscale ion-implantation,"Manipulating the strain induced poly-domains and phase transition in
+correlated oxide material are important for high performance devices
+fabrication. Though the electronic transport in the strained oxide film at
+macroscopic scales can be directly measured, the anisotropic electronic state
+and the controllable phase separation cross the insulator-to-metal transition
+within nanoscale size are still elusive. Here, we selected VO2 crystal film as
+a prototypical oxide and achieved the manipulation of anisotropy electronic
+phase separation via injecting He+ nanobeam into VO2 film at room temperature.
+In addition, this nanoscale phase separation was directly visualized by
+infrared near-field imaging measurements, showing the pronounced and unique
+cR-axis dependent anisotropy on VO2 surface. Our results offered new insights
+towards understanding the anisotropic nanoscale phase separation in strained
+metal oxide films.",2101.07093v2
+2012-05-15,Probing individual layers in functional oxide multilayers by wavelength-dependent Raman scattering,"Integration of functional oxides on silicon requires the use of complex
+heterostructures involving oxides of which the structure and properties
+strongly depend on the strain state and strain-mediated interface coupling. The
+experimental observation of strain-related effects of the individual components
+remains challenging. Here we report a Raman scattering investigation of complex
+multilayer BaTiO3/LaNiO3/CeO2/YSZ thin film structures on silicon. It is shown
+that the Raman signature of the multilayers differs significantly for three
+different laser wavelengths (633, 442 and 325 nm). Our results demonstrate that
+Raman scattering at various wavelengths allows both the identification of the
+individual layers of a functional oxide multilayers and monitoring their strain
+state. It is shown that all layers of the investigated multilayer are strained
+with respect to the bulk reference samples, and that strain induces a new
+crystal structure in the embedded LaNiO3. Based on this, we demonstrate that
+Raman scattering at various wavelengths offers a well-adapted, non-destructive
+probe for the investigation of strain and structure changes, even in complex
+thin film heterostructures.",1205.3334v2
+2012-05-18,Surface oxide on thin films of yttrium hydride studied by neutron reflectometry,"The applicability of standard methods for compositional analysis is limited
+for H-containing films. Neutron reflectometry is a powerful, non-destructive
+method that is especially suitable for these systems due to the large negative
+scattering length of H. In this work we demonstrate how neutron reflectometry
+can be used to investigate thin films of yttrium hydride. Neutron reflectometry
+gives a strong contrast between the film and the surface oxide layer, enabling
+us to estimate the oxide thickness and oxygen penetration depths. A surface
+oxide layer of 5-10 nm thickness was found for unprotected yttrium hydride
+films.",1205.4132v1
+2017-04-25,Graphene oxide adsorptive power from better to more via an enhanced route in perspective,"Adsorption is one important way applied to water decontamination, where
+carbon is commonly used as highly effective absorbent. Carbon of different
+morphologies and structures normally demonstrate distinct capabilities to
+adsorption-typed decontaminations. Graphene oxide is regarded as the oxidative
+derivative of graphene, maintaining its 2D morphology-featuring structure while
+location-dependently immobilized with a large amount of various
+oxygen-involving functional moieties on both sides. Free-standing graphene
+oxide tends to fully unfold in water and behave in macromolecular-like Brownian
+motion. Therefore, high-performance adsorption occurs during the process of
+interacting with large amount of sorbates, during which an unevenness of
+effective adsorptive site distribution turns out for targeted matter due to
+functional group-to-sorbate interaction mechanism differentiation as well as
+groups'inherent location specifications. Thus, oriented manipulation of
+surficial functional moieties and their site distribution is potentially a way
+to further enhance the adsorptive performances, and this could go even better
+if considering combining adsorption and an in-situ manipulation at the same
+time.",1705.00523v1
+2017-05-07,Two-Dimensional Arsenene Oxide: A Realistic Large-gap Quantum Spin Hall Insulator,"Searching for two-dimensional (2D) realistic materials able to realize
+room-temperature quantum spin Hall (QSH) effects is currently a growing field.
+Here, we through ab initio calculations to identify arsenene oxide, AsO, as an
+excellent candidate, which demonstrates high stability, flexibility, and
+tunable spin-orbit coupling (SOC) gaps. In contrast to known pristine or
+functionalized arsenene, the maximum nontrivial band gap of AsO reaches 89 meV,
+and can be further enhanced to 130 meV under biaxial strain. By sandwiching 2D
+AsO between BN sheets, we propose a quantum well in which the band topology of
+AsO is preserved with a sizeable band gap. Considering that AsO having fully
+oxidized surfaces are naturally stable against surface oxidization and
+degradation, this functionality provides a viable strategy for designing
+topological quantum devices operating at room temperature.",1705.02538v1
+2017-11-26,Manganese oxide nano flakes onto simultaneously activated defective CNTs for the creation of CNTs-graphene supported oxygen reduction composite catalysts applied in air fuel cell,"Rational combination holds the key for non-precious metal oxides and economic
+carbon materials to the creation of high performance air electrode materials.
+Carbon nanotubes (CNTs)-supported manganese oxides composite catalysts (CMnCs)
+were obtained by reacting commercial CNTs with MnO$_4^-$ in diluted H$_2$SO$_4$
+with cancelling conventional hydrothermal processing or adding surfantant
+templates. CMnCs were then assembled into commercial air cathodes equipped in
+metal air fuel cells. CNTs demonstrated structurally much defective. Outer CNT
+walls were cracked into graphene nano pieces yet remaining partially attached
+to inner carbon tubes during synthesis. This exposure of graphene planes
+exhibited additional oxygen reduction reactivity. Manganese oxide flakes
+identified as {\gamma}-MnOOH were homogeneously grown on surfaces of CNTs at
+nano sizes. Its deposition density was closely related to the additive amount
+of KMnO$_4$ with regard to CNTs. The ORR activities of sole CMnCs exceeded both
+raw CNTs and competent market catalysts under identical conditions, and with
+current production technics the CMnCs-ingrediented air fuel cells were capable
+of outputting ~15% more power at 100 mA/cm$^2$.",1711.09403v1
+2018-06-11,Study of the oxidation process of crystalline powder of In 2 S 3 and thin films obtained by Dr Blade method,"Good quality In2S3 films were grown by Dr Blade method from a powder
+synthesized in a chemical bath, and oxidized to obtain In2O3 films and films of
+intermediate composition. The oxidation process and kinetics are studied by
+means of thermogravimetric analysis, which shows complex phenomena. The study
+is completed by scanning electron microscopy and EDX measurements. X-ray
+diffraction and UV-visible spectroscopy results are also shown. The oxidation
+process begins significantly above 420 C, and it appears that at least one
+intermediate crystal phase takes place in the solid solution, suggesting that
+the replacement of sulfur by oxygen atoms occurs at different temperatures in
+the different crystallographic sites. The obtained samples show a band gap
+varying continuously between 1.94 eV and 3.72 eV.",1806.03946v1
+2018-08-24,Thermally Oxidized Two-dimensional TaS2 as a High-\k{appa} Gate Dielectric for MoS2 Field-Effect Transistors,"We report a new approach to integrating high-\k{appa} dielectrics in both
+bottom- and top-gated MoS2 field-effect transistors (FETs) through thermal
+oxidation and mechanical assembly of layered twodimensional (2D) TaS2. Combined
+X-ray photoelectron spectroscopy (XPS), optical microscopy, atomic force
+microscopy (AFM), and capacitance-voltage (C-V) measurements confirm that
+multilayer TaS2 flakes can be uniformly transformed to Ta2O5 with a high
+dielectric constant of ~ 15.5 via thermal oxidation, while preserving the
+geometry and ultra-smooth surfaces of 2D TMDs. Top-gated MoS2 FETs fabricated
+using the thermally oxidized Ta2O5 as gate dielectric demonstrate a high
+current on/off ratio approaching 106, a subthreshold swing (SS) down to 61
+mV/dec, and a field-effect mobility exceeding 60 cm2V-1 s-1 at room
+temperature, indicating high dielectric quality and low interface trap density.",1808.08303v1
+2018-08-27,A Micro-mechanical Approach to Model Thermo-Oxidative Aging in Elastomers,"This paper presents a micro-mechanical approach to describe the effects of
+thermo-oxidation on the constitutive behavior of aged elastomers at the
+long-range timescales. In particular, this model focuses on the effects of
+thermo-oxidative aging on the quasi-static mechanical response of elastomer and
+their inelastic responses such as Mullins effect and permanent set over time.
+The model is validated with respect to a comprehensive set of experimental data
+designed by Johlitz et al. to capture thermo-oxidative effect on constitutive
+behavior of elastomers. Besides accuracy, the model is relatively simple and
+easy to fit. It requires ten material parameters, all with clear physical
+meaning, which can be derived from only one set of experiment.",1808.08934v2
+2018-08-28,Metal Oxidation Kinetics and the Transition from Thin to Thick Films,"We report an investigation of growth kinetics and transition from thin to
+thick films during metal oxidation. In the thin film limit (< 20 nm), Cabrera
+and Mott's theory is usually adopted by explicitly considering ionic drift
+through the oxide in response to electric fields, where the growth kinetics
+follow an inverse logarithmic law. It is generally accepted that Wagner's
+theory, involving self-diffusion, is valid only in the limit of thick film
+regime and leads to parabolic growth kinetics. Theory presented here unifies
+the two models and provides a complete description of oxidation including the
+transition from thin to thick film. The range of validity of Cabrera and Mott's
+theory and Wagner's theory can be well defined in terms of the Debye-Huckel
+screening length. The transition from drift-dominated ionic transport for thin
+film to diffusion-dominated transport for thick film is found to strictly
+follow the direct logarithmic law that is frequently observed in many
+experiments.",1808.09570v1
+2019-02-25,Molybdenum oxide hole selective transport layer by hot wire oxidation-sublimation deposition for silicon heterojunction solar cells,"In this article, a novel hot wire oxidation-sublimation deposition (HWOSD)
+technique was developed to prepare molybdenum oxide (MoOx) thin films with high
+quality. Silicon heterojunction (SHJ) solar cells with the HWOSD MoOx as a hole
+selective transport layer (HSL) were fabricated. Thickness of the MoOx layer
+and annealing process of the solar cells were studied and optimized. A power
+conversion efficiency up to 21.10% was achieved on a SHJ solar cell using a
+14nm MoOx layer as the HSL. Dark current density-voltage-temperature (J-V-T)
+characteristics of the SHJ solar cell were measured at the temperatures from
+200K to 380K. Transport processes including thermionic emission of electrons
+over the potential barrier and quantum assisted tunneling of holes through the
+gap states in the MoOx layer were proposed for the MoOx/n c-Si heterojunction.
+The investigation of the transport mechanisms provides us a better
+understanding of the characteristics of the novel SHJ solar cells and it is
+helpful for us to fully demonstrate the potential of such kind of solar cells
+in the future.",1902.09127v1
+2019-03-28,Quantized conductance in a one-dimensional ballistic oxide nanodevice,"Electric-field effect control of two-dimensional electron gases (2-DEG) has
+enabled the exploration of nanoscale electron quantum transport in
+semiconductors. Beyond these classical materials, transition metal-oxide-based
+structures have d-electronic states favoring the emergence of novel quantum
+orders absent in conventional semiconductors. In this context, the
+LaAlO3/SrTiO3 interface that combines gate-tunable superconductivity and
+sizeable spin-orbit coupling is emerging as a promising platform to realize
+topological superconductivity. However, the fabrication of nanodevices in which
+the electronic properties of this oxide interface can be controlled at the
+nanoscale by field-effect remains a scientific and technological challenge.
+Here, we demonstrate the quantization of conductance in a ballistic quantum
+point contact (QPC), formed by electrostatic confinement of the LaAlO3/SrTiO3
+2-DEG with a split-gate. Through finite source-drain voltage, we perform a
+comprehensive spectroscopic investigation of the 3d energy levels inside the
+QPC, which can be regarded as a spectrometer able to probe Majorana states in
+an oxide 2-DEG.",1903.12134v1
+2019-04-11,Asymmetric Lattice Disorder Induced at Oxide Interfaces,"Control of order-disorder phase transitions is a fundamental materials
+science challenge, underpinning the development of energy storage technologies
+such as solid oxide fuel cells and batteries, ultra-high temperature ceramics,
+and durable nuclear waste forms. At present, the development of promising
+complex oxides for these applications is hindered by a poor understanding of
+how interfaces affect lattice disordering processes and defect transport. Here
+we explore the evolution of local disorder in ion-irradiated La$_2$Ti$_2$O$_7$
+/ SrTiO$_3$ thin film heterostructures using a combination of high-resolution
+scanning transmission electron microscopy (STEM), position-averaged convergent
+beam electron diffraction (PACBED), electron energy loss spectroscopy
+(STEM-EELS), and \textit{ab initio} theory calculations. We observe highly
+non-uniform lattice disordering driven by asymmetric oxygen vacancy formation
+across the interface. Our calculations indicate that this asymmetry results
+from differences in the polyhedral connectivity and vacancy formation energies
+of the two interface components, suggesting ways to manipulate lattice disorder
+in functional oxide heterostructures.",1904.05932v2
+2019-04-18,Anomalous conduction band fluctuation in silicon carbide metal-oxide-semiconductor structures revealed by electrical characterization of field effect transistors combined with self-consistent numerical calculations,"We determined the interface state density ($D_{\rm it}$) distributions in the
+vicinity of the conduction band edge in silicon carbide (SiC)
+metal-oxide-semiconductor (MOS) structures by reproducing the experimental
+current-voltage characteristics of MOS field effect transistors (MOSFETs) with
+numerical calculations. In the calculation, potential distributions and energy
+sub-bands in the inversion layer were calculated by solving Poisson and
+Schr\""{o}dinger equations, respectively. We demonstrate that gate
+characteristics of the MOSFETs are well described by considering that the
+interface states are caused by fluctuation of free-electron density of states
+in a two-dimensional system. The $D_{\rm it}$ distributions are almost uniquely
+determined by the oxide formation process (as oxidation or interface
+nitridation) and independent of the acceptor concentration
+($3\times10^{15}-1\times10^{18}\ {\rm cm^{-3}}$).",1904.08574v1
+2019-04-21,Oxidized silicon sulfide: stability and electronic properties of a novel two-dimensional material,"Isolated oxygen impurities and fully oxidized structures of four stable
+two-dimensional (2D) SiS structures are investigated by {\em ab initio} density
+functional calculations. Binding energies of oxygen impurities for all the four
+2D SiS structures are found larger than those for phosphorene, due to the lower
+electronegativity of Si atoms. The most stable configurations of isolated
+oxygen impurities for different 2D SiS structures are decided and the
+corresponding 2D structures with saturated oxidation (SiSO) are predicted.
+Among all the four fully oxidized structures, $\alpha$-SiSO is demonstrated to
+be stable by phonon spectra calculations and molecular dynamics (MD)
+simulations. Electronic structure calculations indicate that $\alpha$-SiSO
+monolayer is semiconducting with a direct band gap of ${\approx}2.28$~eV, which
+can be effectively tuned by in-layer strain. The value of band gap and
+thermodynamic stability are found depending sensitively on the saturation level
+of oxygen.",1904.09614v1
+2019-08-19,Symbolic Regression Discovery of New Perovskite Catalysts with High Oxygen Evolution Reaction Activity,"Symbolic regression (SR) is an emerging method for building analytical
+formulas to find models that best fit data sets. Here, SR was used to guide the
+design of new oxide perovskite catalysts with improved oxygen evolution
+reaction (OER) activities. An unprecedentedly simple descriptor, {\mu}/t, where
+{\mu} and t are the octahedral and tolerance factors, respectively, was
+identified, which accelerated the discovery of a series of new oxide perovskite
+catalysts with improved OER activity. We successfully synthesized five new
+oxide perovskites and characterized their OER activities. Remarkably, four of
+them, Cs0.4La0.6Mn0.25Co0.75O3, Cs0.3La0.7NiO3, SrNi0.75Co0.25O3, and
+Sr0.25Ba0.75NiO3, outperform the current state-of-the-art oxide perovskite
+catalyst, Ba0.5Sr0.5Co0.8Fe0.2O3 (BSCF). Our results demonstrate the potential
+of SR for accelerating data-driven design and discovery of new materials with
+improved properties.",1908.06778v1
+2019-11-12,Structure and Chemistry of Graphene Oxide in Liquid Water from First Principles,"Graphene oxide is a rising star among 2D materials, yet its interaction with
+liquid water remains a fundamentally open question: experimental
+characterization at the atomic scale is difficult, and modelling by classical
+approaches cannot properly describe chemical reactivity. Here, we bridge the
+gap between simple computational models and complex experimental systems, by
+realistic first-principles molecular simulations of graphene oxide (GO) in
+liquid water. We construct chemically accurate GO models and study their
+behavior in water, showing that oxygen-bearing functional groups (hydroxyl and
+epoxides) are preferentially clustered on the graphene oxide layer. We
+demonstrated the specific properties of GO in water, an unusual combination of
+both hydrophilicity and fast water dynamics. Finally, we evidence that GO is
+chemically active in water, acquiring an average negative charge of the order
+of 10~mC m$^{-2}$. The ab initio modelling highlights the uniqueness of GO
+structures for applications as innovative membranes for desalination and water
+purification.",1911.04987v2
+2019-11-14,Bandgap Measurement of Reduced Graphene Oxide Monolayers through Scanning Tunnelling Spectroscopy,"Most popular atomically thin carbon material, called graphene, has got no
+band gap and this particular property of graphene makes it less useful from the
+aspect of nanoscale transistor devices. The band gap can be introduced in the
+graphene if it is synthesized through chemical route. First, Graphene Oxide
+(GO) is made which further go under reduction and turns into Reduced Graphene
+Oxide (RGO). Band structure investigation of monolayer sheets of reduced
+graphene oxide (RGO) by Scanning Tunneling Spectroscopy (STS) has been
+investigated here. The GO sheets are 1-1.2 nm thick and become more thinner
+after reduction. The band gap of GO was found in the range of 0.8 eV. The RGO
+showed up a variety of band structure. RGO opens a new field of study of
+atomically thin layers of carbon because it has got non zero band gap which is
+not the case for graphene.",1911.06230v1
+2019-11-15,Yttrium Tantalum Oxynitride Multiphases as Photoanodes for Water Oxidation,"Perovskite yttrium tantalum oxynitride is theoretically proposed as a
+promising semiconductor for solar water splitting because of the predicted
+bandgap and energy positions of band edges. In experiment, however, we show
+here that depending on processing parameters, yttrium tantalum oxynitrides
+exist in multiphases, including the desired perovskite YTaON2, defect fluorite
+YTa(O,N,o)4, and N-doped YTaO4. These multiphases have bandgaps ranging between
+2.13 and 2.31 eV, all responsive to visible light. The N-doped YTaO4,
+perovskite main phase, and fluorite main phase derived from crystalline
+fergusonite oxide precursors exhibit interesting photoelectrochemical
+performances for water oxidation, while the defect fluorite derived from low
+crystallized scheelite-type oxide precursors show negligible activity.
+Preliminarily measurements show that loading IrOx cocatalyst on N-doped YTaO4
+significantly improves its photoelectrochemical performance encouraging further
+studies to optimize this new material for solar fuel production.",1911.06550v1
+2019-11-27,"Controlled Preparation, Characterization, and Bandgap Modulation of RF Sputtered Antimony Vanadium Oxide (SbVO4) Thin Films","In this paper, RF sputtered antimony vanadium oxide (SbVO4) thin films and
+its characterization are reported. High purity sputtering targets were
+fabricated by sintering a mixture of Sb2O3 and V2O5 powders. Thin films were
+deposited by reactive sputtering at various temperature and argon/oxygen
+partial pressures. Several growth parameters and surface chemistry were studied
+by applying numerous optical and electrochemical characterization technique. It
+is found that SbVO4 exhibits an indirect band gap in the range of 1.89 eV to
+2.36 eV and has desirable valence band position to drive water oxidation
+reaction under illumination. The bandgap depends heavily on stoichiometry of
+the film and can be modulated by incorporating controlled amount of oxygen gas
+in plasma environment. Optimized SbVO4 photoanodes was designed and tested for
+photoelectrochemical water oxidation catalysis. Preliminary studies show that
+these electrodes possess n-type catalytic behavior in alkaline media. The
+prepared SbVO4 thin films, with typical film thickness was around 400 nm,
+contain nanoparticles having the sizes of 10-15 nm.",1911.12171v1
+2020-03-06,Emerging classes of antioxidant to cancer therapy: a review of clinical and experimental studies,"This review mainly focuses on the relation between antioxidants with cancer
+therapy. Antioxidants have been reported to play an essential role to reduce
+free radical species. Free radicals commonly cause oxidative damage which is a
+common factor in the aging process, and also the vital factor of formation, and
+development of major disease specially cancer. Although, since last many
+decades several antioxidants belong to natural and synthetic origin have been
+tested in clinical trials against oxidative stress, however these clinical
+trials end up with undesirable effects. This review also complied with the most
+recent findings of oxidative stress, highlighting of free racial production,
+and its related oxidative damage at cellular and molecular level, with the new
+and existing natural and synthetic classes of free radical scavenger and their
+related clinical trials.",2003.04538v1
+2020-03-25,Birefringent Graphene Oxide Liquid Crystals in Micro-channels for Optical Switch,"We propose a mechanical-hydrodynamical experimental setup in which the
+microfluidic motion manipulates the optical birefringence of levitated graphene
+oxide liquid crystal. The birefringence of the sample is changed by flowing
+graphene oxide liquid crystal in the micro-channel. By measuring the ordinary
+and extraordinary refractive indices at five flow rates, one can determine the
+value of the birefringence of the samples, precisely. Our results demonstrate
+that, by adjusting the concentration and flow rate of dispersion of the
+graphene oxide nano flakes, the induced birefringence can be controlled. It is
+also shown that this approach can be used as an optical switch.",2003.11600v1
+2020-05-07,"Combining density functional theories to correctly describe the energy, lattice structure and electronic density of functional oxide perovskites","Functional oxide perovskites are the pillar of cutting-edge technological
+applications. Density functional theory (DFT) simulations are the theoretical
+methods of choice to understand and design perovskite materials. However, tests
+on the reliability of DFT to describe fundamental properties of oxide
+perovskites are scarce and mostly ill-defined due to a lack of rigorous
+theoretical benchmarks for solids. Here, we present a quantum Monte Carlo
+benchmark study of DFT on the archetypal perovskite BaTiO$_{3}$ (BTO). It shows
+that no DFT approximation can simultaneously reproduce the energy, structure,
+and electronic density of BTO. Traditional protocols to select DFT
+approximations are empirical and fail to detect this shortcoming. An approach
+combining two different non-empirical DFT schemes, ""SCAN"" and ""HSE06"", is able
+to holistically describe BTO with accuracy. Combined DFT approaches should thus
+be considered as a promising alternative to standard methods for simulating
+oxide perovskites.",2005.03792v1
+2020-05-15,Optimization of allotropic and hardness of aluminum oxide coating by PEO,"One of the most important methods of producing materials and oxide coating is
+plasma electrolytic oxidation (PEO). Coatings made on aluminum in PEO method
+have two allotropes of $\alpha$-Al$_2$O$_3$ and $\gamma$-Al$_2$O$_3$. Coatings
+containing $\alpha$-Al$_2$O$_3$ have more hardness and wear resistance;
+therefore, the main goal of the present study is to optimize aluminum oxide
+allotrope for increasing the ratio of $\alpha$-Al$_2$O$_3$ in coating made with
+PEO method. Results of the present study shows that the optimum electrolyte
+compound for making highest phase of $\alpha$-Al$_2$O$_3$ has 2.9 g/lit of KOH,
+1.15 g/lit of Na4P2O7, and 0.34 g/lit of NaAlO2 and ratio of highest allotropic
+pick of $\alpha$-Al$_2$O$_3$ to highest allotropic pick of $\gamma$-Al$_2$O$_3$
+(in XRD test) in the optimum condition is 0.622 and hardness is 1648 Vickers.",2005.07471v1
+2020-06-19,Predicting the phase stability of multi-component high entropy compounds,"A generic method to estimate the relative feasibility of formation of high
+entropy compounds in a single phase, directly from first principles, is
+developed. As a first step, the relative formation abilities of 56
+multi-component, AO, oxides were evaluated. These were constructed from 5
+cation combinations chosen from A={Ca, Co, Cu, Fe, Mg, Mn, Ni, Zn}. Candidates
+for multi-component oxides are predicted from descriptors related to the
+enthalpy and configurational entropy obtained from the mixing enthalpies of two
+component oxides. The utility of this approach is evaluated by comparing the
+predicted combinations with the experimentally realized entropy stabilized
+oxide, (MgCoCuNiZn)O. In the second step, Monte Carlo simulations are utilized
+to investigate the phase composition and local ionic segregation as a function
+of temperature. This approach allows for the evaluation of potential secondary
+phases, thereby making realistic predictions of novel multi-component compounds
+that can be synthesized.",2006.11231v2
+2020-06-24,Tip-induced oxidation of silicene nano-ribbons,"We report on the oxidation of self-assembled silicene nanoribbons grown on
+the Ag(110) surface using Scanning Tunneling Microscopy and High-Resolution
+Photoemission Spectroscopy. The results show that silicene nanoribbons present
+a strong resistance towards oxidation using molecular oxygen. This can be
+overcome by increasing the electric field in the STM tunnel junction above a
+threshold of +2.6 V to induce oxygen dissociation and reaction. The higher
+reactivity of the silicene nanoribbons towards atomic oxygen is observed as
+expected. The HR-PES confirm these observations: Even at high exposures of
+molecular oxygen, the Si 2p core-level peaks corresponding to pristine silicene
+remain dominant, reflecting a very low reactivity to molecular oxygen. Complete
+oxidation is obtained following exposure to high doses of atomic oxygen; the Si
+2p core level peak corresponding to pristine silicene disappears.",2006.13780v1
+2020-08-06,Electrochemical oxidation of CO on Cu single crystals under alkaline conditions,"We perform a joint experimental-theoretical study of the electrochemical
+oxidation of CO on copper (Cu) under alkaline conditions. Using cyclic
+voltammetry on Cu single crystal surfaces, we demonstrate that both Cu terraces
+and steps show CO oxidation activity at potentials just slightly positive
+(0.03-0.14 V) of the thermodynamic equilibrium potential. The overpotentials
+are 0.23-0.12 V lower than that of gold (approx. 0.26 V), which up until now
+has been considered to be the most active catalyst for this process. Our
+theoretical calculations suggest that Cu's activity arises from the
+advantageous combination of simultaneous *OH adsorption under CO oxidation
+potentials and surmountable *CO-*OH coupling barriers. Experimentally observed
+onset potentials are in agreement with the computed onsets of *OH adsorption.
+We furthermore show that the onsets of *OH adsorption on steps are more
+affected by *CO-*OH interactions than on terraces due to a stronger competitive
+adsorption. Overall, Cu(100) shows the lowest overpotential (0.03 V) of the
+facets considered.",2008.02675v2
+2020-08-25,Cathode Materials for Lithium Ion Batteries (LIBs): A Review on Materials related aspects towards High Energy Density LIBs,"This article reviews the development of cathode materials for secondary
+lithium ion batteries since its inception with the introduction of lithium
+cobalt oxide in early 1980s. The time has passed and numerous cathode materials
+are designed and developed to realize not only the enhanced capacity but also
+the power density simultaneously. However, there are numerous challenges such
+as the cyclic stability of cathode materials, their structural and thermal
+stability, higher operating voltage together with high ionic and electronic
+conductivity for efficient ion and charge transport during charging and
+discharging. This article will cover the development of materials in
+chronological order classifying as the lithium ion cathode materials in
+different generations. The ternary oxides such as LiTMOx (TM=Transition Metal)
+are considered as the first generation materials, whereas modified ternary and
+quaternary oxide systems are considered as the second generation materials. The
+current i.e. third generation includes complex oxide systems with higher
+lithium content such as Li2TMSiO4 aiming for higher energy density. Further,
+developments are heading towards lithium metal based batteries with a
+possibility for very high energy densities.",2008.10896v2
+2020-09-10,Effect of oxygen adsorption and oxidation on the strain state of Pd nanocrystals,"X-ray powder diffraction using a synchrotron light source reveals significant
+modifications to both morphology and strain state in Palladium nanocubes after
+oxidation. Short-range strain measured by the static component of the
+Debye-Waller coefficient is observed to be higher in the oxidized
+nanoparticles; while long-range strain related to the line broadening of the
+diffraction peaks is seen to decrease. Using multiscale modelling with
+classical molecular dynamics and density functional theory, we connect the
+decrease in long-range strain to the increased truncation of the oxidized
+nanocubes, while the higher short-range strain is shown to be due to surface
+softening from oxygen adsorption. Different surface disorder on different
+crystallographic facets lead to opposing trends for oxygen activation on the
+different exposed surfaces of the truncated nanoparticles.",2009.04736v1
+2020-10-20,Signatures of technetium oxidation states: a new approach,"A general strategy for the determination of Tc oxidation state by new
+approach involving X-ray absorption near edge spectroscopy (XANES) at the Tc L3
+edge is shown. A comprehensive series of 99Tc compounds, ranging from oxidation
+states I to VII, was measured and subsequently simulated within the framework
+of crystal-field multiplet theory. The observable trends in the absorption edge
+energy shift in combination with the spectral shape allow for a deeper
+understanding of complicated Tc coordination chemistry. This approach can be
+extended to numerous studies of Tc systems as this method is one of the most
+sensitive methods for accurate Tc oxidation state and ligand characterization.",2010.10164v2
+2020-11-12,Topological phonons in oxide perovskites controlled by light,"Perovskite oxides exhibit a rich variety of structural phases hosting
+different physical phenomena that generate multiple technological applications.
+We find that topological phonons, i.e., nodal rings, nodal lines, and Weyl
+points, are ubiquitous in oxide perovskites in terms of structures (tetragonal,
+orthorhombic, and rhombohedral), compounds (BaTiO3, PbTiO3, and SrTiO3), and
+external conditions (photoexcitation, strain, and temperature). In particular,
+in the tetragonal phase of these compounds, all types of topological phonons
+can simultaneously emerge when stabilized by photoexcitation, whereas the
+tetragonal phase stabilized by thermal fluctuations only hosts a more limited
+set of topological phonon states. Additionally, we find that the photoexcited
+carrier concentration can be used to tune the topological phonon states and
+induce topological transitions even without associated structural phase
+changes. Overall, we propose oxide perovskites as a versatile platform in which
+to study topological phonons and their manipulation with light.",2011.06269v1
+2020-11-16,Artificial oxide heterostructures with non-trivial topology,"In the quest for topological insulators with large band gaps,
+heterostructures with Rashba spin-orbit interactions come into play. Transition
+metal oxides with heavy ions are especially interesting in this respect. We
+discuss the design principles for stacking oxide Rashba layers. Assuming a
+single layer with a two-dimensional electron gas (2DEG) on both interfaces as a
+building block, a two-dimensional topological insulating phase is present when
+negative coupling between the 2DEGs exists. When stacking multiple building
+blocks, a two-dimensional or three-dimensional topological insulator is
+artificially created, depending on the intra- and interlayer coupling strengths
+and the number of building blocks. We show that the three-dimensional
+topological insulator is protected by reflection symmetry, and can therefore be
+classified as a topological crystalline insulator. In order to isolate the
+topological states from bulk states, the intralayer coupling term needs to be
+quadratic in momentum. It is described how such a quadratic coupling could
+potentially be realized by taking buckling within the layers into account. The
+buckling, thereby, brings the idea of stacked Rashba system very close to the
+alternative approach of realizing the buckled honeycomb lattice in
+[111]-oriented perovskite oxides.",2011.07988v1
+2020-11-17,Effect of Substrate Roughness on Oxidation Resistance of an Aluminized Ni-Base Superalloy,"In the present work, it is shown that the surface preparation method used on
+two Ni-based superalloys prior to aluminizing chemical vapor deposition (CVD)
+is one of the most important factors determining the oxidation resistance of
+aluminized Ni-based superalloys. It was found that grit blasting the substrate
+surface negatively affects the oxidation resistance of the aluminized coatings.
+For grit blasted and aluminized IN 625, a thicker outer NiAl coating was formed
+compared to that of IN 738. In contrast, no effect on NiAl coating thickness
+was found for grit blasted and aluminized IN 738. However, a thicker
+interdiffusion zone (IDZ) was observed. It was shown that the systems with
+grit-blasted surfaces reveal worse oxidation resistance during thermal shock
+tests, namely, a higher mass loss was observed for both grit blasted and
+aluminized alloys, as compared to ground and aluminized alloys. A possible
+reason for this effect of remaining alumina particles originating from surface
+grit blasting on the diffusion processes and stress distribution at the
+coating/substrate is proposed.",2011.08921v1
+2021-02-15,Universal Fabrication of Two-Dimensional Electron Systems in Functional Oxides,"Two-dimensional electron systems (2DESs) in functional oxides are promising
+for applications, but their fabrication and use, essentially limited to
+SrTiO$_3$-based heterostructures, are hampered by the need of growing complex
+oxide over-layers thicker than 2~nm using evolved techniques. This work shows
+that thermal deposition of a monolayer of an elementary reducing agent suffices
+to create 2DESs in numerous oxides.",2102.07748v1
+2021-02-23,Combined Iodine- and Sulfur-based Treatments for an Effective Passivation of GeSn Surface,"GeSn alloys are metastable semiconductors that have been proposed as building
+blocks for silicon-integrated short-wave and mid-wave infrared photonic and
+sensing platforms. Exploiting these semiconductors requires, however, the
+control of their epitaxy and their surface chemistry to reduce non-radiative
+recombination that hinders the efficiency of optoelectronic devices. Herein, we
+demonstrate that a combined sulfur- and iodine-based treatments yields
+effective passivation of Ge and Ge0.9Sn0.1 surfaces. X-ray photoemission
+spectroscopy and in situ spectroscopic ellipsometry measurements were used to
+investigate the dynamics of surface stability and track the reoxidation
+mechanisms. Our analysis shows that the largest reduction in oxide after HI
+treatment, while HF+(NH4)2S results in a lower re-oxidation rate. A combined
+HI+(NH4)2S treatment preserves the lowest oxide ratio <10 % up to 1 hour of air
+exposure, while less than half of the initial oxide coverage is reached after 4
+hours. These results highlight the potential of S- and I-based treatments in
+stabilizing the GeSn surface chemistry thus enabling a passivation method that
+is compatible with materials and device processing.",2102.11908v1
+2021-03-30,Oxide spin-orbitronics: spin-charge interconversion and topological spin textures,"Quantum oxide materials possess a vast range of properties stemming from the
+interplay between the lattice, charge, spin and orbital degrees of freedom, in
+which electron correlations often play an important role. Historically, the
+spin-orbit coupling was rarely a dominant energy scale in oxides. It however
+recently came to the forefront, unleashing various exotic phenomena connected
+with real and reciprocal-space topology that may be harnessed in spintronics.
+In this article, we review the recent advances in the new field of oxide
+spin-orbitronics with a special focus on spin-charge interconversion from the
+direct and inverse spin Hall and Edelstein effects, and on the generation and
+observation of topological spin textures such as skyrmions. We highlight the
+control of spin-orbit-driven effects by ferroelectricity and give perspectives
+for the field.",2103.16271v1
+2021-03-30,Cluster Catalysis with Lattice Oxygen: Tracing Oxygen Transport from a Magnetite(001) Support onto Small Pt Clusters,"Oxidation catalysis on reducible oxide-supported small metal clusters often
+involves lattice oxygen. In the present work, we trace the path of lattice
+oxygen from Fe3O4(001) onto small Pt clusters during the CO oxidation, aiming
+at differentiating whether the reaction takes place at the cluster/support
+interface or on the cluster. While oxygen vacancies form on many other
+supports, magnetite maintains its surface stoichiometry upon reduction thanks
+to a high cation mobility. In order to investigate whether size-dependent
+oxygen affinities play a role, we study two specific cluster sizes, Pt5 and
+Pt19. By separating different reaction steps in our experiment, lattice oxygen
+can be accumulated on the clusters. Temperature programmed desorption (TPD) and
+sophisticated pulsed valve experiments indicate that the CO oxidation takes
+place on the Pt clusters rather than at the interface. Scanning tunneling
+microscopy (STM) shows a decrease in apparent height of the clusters, which
+density functional theory (DFT) explains as a restructuring following lattice
+oxygen reverse spillover.",2103.16413v2
+2021-04-04,Characterization of Nb22O54 microrods grown from niobium oxide powders recovered from mine tailings,"In this work, the possibility of using niobium oxide recovered from tailings
+from the Penouta Sn-Nb-Ta deposit (located at the North of Spain) as starting
+material for growing microstructures is demonstrated. The properties of the
+starting material have been studied to understand its crystal structure,
+quality and purity. Recovered niobium oxide powders are mainly of TT-Nb2O5.
+These powders have been used to grow Nb22O54 microrods by an evaporation method
+in an argon atmosphere. Different characterization techniques (X-Ray
+diffraction, scanning electron microscopy, micro-Raman spectroscopy,
+luminescence) have been used to determine the properties of Nb22O54 microrods,
+mainly focusing on the crystal quality and refractive index. The present study
+opens the way to the transformation of waste (mine tailings) into a material of
+high technological value as niobium oxide, and its reintroduction into the
+value chain for a wide range of applications, from coatings to batteries and
+supercapacitors.",2104.01640v1
+2021-04-28,"A Quantum Chemical Approach for the Characterization of the Interaction Potential of Propylene Oxide with Rare-Gas Atoms (He, Ne, Ar)","Propylene oxide is one of the simplest organic chiral molecules and has
+attracted considerable interest from the scientific community a few years ago,
+when it was discovered in the interstellar medium. Here, we report a
+preliminary study on the interaction between propylene oxide and rare-gas
+atoms, specifically He, Ne, and Ar. The interaction potentials as a function of
+the distance between the center-of-mass of propylene oxide and the
+rare-gas-atom are calculated for fourteen leading configurations at
+CCSD(T)/aug-cc-pVDZ level of theory. Symmetry Adapted Perturbation Theory has
+been employed for the analysis of the intermolecular potential, revealing that
+most of the contribution is given by dispersion and exchange forces.",2104.13670v1
+2021-05-31,Stable High Power deep-UV Enhancement Cavity in Ultra High Vacuum with Fluoride Coatings,"We demonstrate the superior performance of fluoride coated versus oxide
+coated mirrors in long term vacuum operation of a high power deep-ultraviolet
+enhancement cavity. In high vacuum ($10^{-8}$ mbar), the fluoride optics can
+maintain up to a record-high 10 w of stable intracavity power on one hour time
+scales, whereas for the oxide optics, we observe rapid degradation at lower
+intracavity powers with a rate that increases with power. After observing
+degradation in high vacuum, we can recover the fluoride and oxide optics with
+oxygen; however, this recovery process becomes ineffective after several
+applications. For fluoride coatings, we see that initial UV conditioning in an
+oxygen environment helps to improve the performances of the optics. In
+oxygen-rich environments from $\sim 10^{-4}$ mbar to 1 mbar, the fluoride
+optics can stably maintain up to 20 W of intracavity power on several-hour time
+scales whereas for the oxide optics there is immediate degradation with a rate
+that increases with decreasing oxygen pressure.",2105.14977v1
+2021-06-04,A statistical analysis of pores and micro-cracks in nuclear graphite,"Microstructure characterization is of great value to understanding nuclear
+graphite's properties and irradiation behavior. However, graphite is soft and
+could be easily damaged during sample preparation. A three-step polishing
+method involving mechanical polishing, ion milling and rapid oxidation is
+proposed for graphite. Ion milling is adopted to remove the broken graphite
+pieces produced by mechanical polishing. Rapid oxidation is then adopted to
+remove irradiation-induced damage layer during ion milling. The Raman spectra
+show very low G peak width and ID/IG ratio after rapid oxidation, indicating a
+surface completely free from artificial defects. The micro-cracks which were
+conventionally observed via a transmission electron microscope can be observed
+on rapid-oxidized surface in a scanning electron microscope. By digital image
+processing, the micro-cracks along with the gas-escape pores in nuclear
+graphite IG-110 are statistically analyzed. Porosity's distributions on crack
+(pore) size (spanning from 10 nm to 100 um) are given, which could help to
+understand and simulate graphite's performances in reactors.",2106.02321v1
+2021-07-02,Machine learning of microscopic ingredients for graphene oxide/cellulose interaction,"Understanding the role of microscopic attributes in nanocomposites allows for
+a controlled and, therefore, acceleration in experimental system designs. In
+this work, we extracted the relevant parameters controlling the graphene oxide
+binding strength to cellulose by combining first-principles calculations and
+machine learning algorithms. We were able to classify the systems among two
+classes with higher and lower binding energies, which are well defined based on
+the isolated graphene oxide features. By a theoretical X-ray photoelectron
+spectroscopy analysis, we show the extraction of these relevant features.
+Additionally, we demonstrate the possibilities of a refined control within a
+machine learning regression between the binding energy values and the system's
+characteristics. Our work presents a guiding map to the control graphene
+oxide/cellulose interaction.",2107.01040v1
+2021-07-05,"First Principles, Explicit Interface Studies of Oxygen Vacancy and Chloride in Alumina Films for Corrosion Applications","Pitting corrosion is a much-studied and technologically relevant subject.
+However, the fundamental mechanisms responsible for the breakdown of the
+passivating oxide layer are still subjects of debate. Chloride anions are known
+to accelerate corrosion; relevant hypotheses include Cl insertion into
+positively charged oxygen vacancies in the oxide film, and Cl adsorption on
+passivating oxide surfaces, substituting for surface hydroxyl groups. In this
+work, we conduct large-scale first principles modeling of explicit
+metal/Al(2)O(3) interfaces to investigate the energetics and electronic
+structures associated with these hypotheses. The explicit interface models
+allow electron transfer that mimics electrochemical events, and the
+establishment of the relation between atomic structures at different interfaces
+and the electronic band alignment. For multiple model interfaces, we find that
+doubly charged oxygen vacancies, which are key ingredients of the point defect
+model (PDM) often used to analyze corrosion data, can only occur in the
+presence of a potential gradient that raises the voltage. Cl-insertion into
+oxide films can be energetically favorable in some oxygen vacancy sites,
+depending on the voltage. We also discuss the challenges associated with
+explicit DFT modeling of these complex interfaces.",2107.02251v1
+2021-09-30,Alkaline CO electro-oxidation: Mechanistic Differences between Copper and Gold Single Crystals and Peculiarities of various Copper Facets,"Understanding CO electro-oxidation is crucial towards designing catalysts for
+electrochemically oxidizing complex organic molecules. Earth-abundant Copper
+(Cu) has recently been demonstrated to exhibit high alkaline CO
+electro-oxidation activity, rivaling the previously acclaimed Gold (Au).
+Herein, we combine single crystal rotating disc electrode (RDE) experiments and
+ab initio microkinetic modeling to understand the underlying reaction
+mechanisms on Cu and Au surfaces. Cu exhibits a facet-dependent activity with
+Cu(111) having a 0.27 V lower overpotential than Au(111) and a comparable CO
+oxidation current density. Using Koutecky-Levich analysis and DFT based
+microkinetic modeling, we identify the rate-limiting pathway to be
+Langmuir-Hinshelwood on Cu whereas Eley-Rideal on Au. We additionally present
+strikingly variant RDE responses on four Cu facets (111, 100, 110 and 211) and
+long-term stability analysis on Cu(111) and Au(111). We find a combined
+reset-reaction profile helps Cu retain its high activity and pose a strong
+competition to the expensive Au catalysts.",2109.15269v2
+2021-10-14,Unveiling Structural Disorders in Honeycomb Layered Oxide: $\rm Na_2Ni_2TeO_6$,"Honeycomb layered oxides have garnered tremendous research interest in a wide
+swath of disciplines owing not only to the myriad physicochemical properties
+they exhibit, but also their rich crystal structural versatility. Herein, a
+comprehensive crystallographic study of a sodium-based $\rm Na_2Ni_2TeO_6$
+honeycomb layered oxide has been performed using atomic-resolution transmission
+electron microscopy, elucidating a plethora of atomic arrangement (stacking)
+disorders in the pristine material. Stacking disorders in the arrangement of
+honeycomb metal slab layers (stacking faults) occur predominantly perpendicular
+to the slabs with long-range coherence length and enlisting edge dislocations
+in some domains. Moreover, the periodic arrangement of the distribution of
+alkali atoms is altered by the occurrence of stacking faults. The multitude of
+disorders innate in $\rm Na_2Ni_2TeO_6$ envisage broad implications in the
+functionalities of related honeycomb layered oxide materials and hold promise
+in bolstering renewed interest in their material science.",2110.09287v1
+2021-10-27,Synthesis and Characterisation of Iron Oxide Nanoparticles with Tunable Sizes by Hydrothermal Method,"The present study investigates the effect of different reaction times on the
+crystallinity, surface morphology and size of iron oxide nanoparticles. In this
+synthetic system, aqueous iron (III) nitrate (Fe(NO$_3$)$_3\cdot9$H$_2$O)
+nonahydrate, provided the iron source and triethylamine was the precipitant and
+alkaline agent. The as-synthesised iron oxide nanoparticles were characterised
+by X-ray diffraction (XRD), Rietveld analysis, Scanning Electron Microscopy
+(SEM) and Fourier transform infrared spectroscopy (FTIR). Prolonged reaction
+times indicated the change on nanoparticle shape from elongated nanorods to
+finally distorted nanocubes. Analysis on the crystallinity of the iron oxide
+nanoparticles suggest that the samples mainly consist of two phases, which are
+Goethite ($\alpha$-FeOOH) and Hematite $(\alpha$-Fe$_2$O$_3$), respectively.",2110.14774v1
+2021-11-15,Probing the polar-nonpolar oxide interfaces using resonant x-ray standing wave techniques,"Transition metal (TM) oxide heterostructure superlattices have attracted
+great attention in research communities because of their emergent interfacial
+phenomena that do not exist in the bulk form. In order to understand the
+mechanisms that cause these phenomena, it is important to use depth-resolved
+spectroscopies to study the electronic structure across the buried oxide
+interfaces. In this review, we focus on the recent applications of standing
+wave (SW) photoemission (SW-XPS) and resonant inelastic x-ray scattering
+(SW-RIXS) spectroscopy to study the depth profiles of electronic structure or
+carriers around the polar-nonpolar oxide interfaces. Using the incident photon
+energies near the TM x-ray absorption resonance, the created SW excitation can
+enhance the spectral response and certain electronic transitions, providing
+important insight into the interfacial electronic structure in the energy and
+real space regimes. Following the background introductions, we describe two SW
+experiments and demonstrate that the combination of SW-XPS and SW-RIXS has the
+potential to obtain the depth distribution of electronic/orbital states around
+the buried interfaces with Angstrom precision.",2111.07539v1
+2021-11-15,Covalent Functionalization of HiPco Single-Walled Carbon Nanotubes: Differences in the Oxidizing Action of H2SO4 and HNO3 during a Soft Oxidation Process,"The results of a study on the evolution of HiPco single-walled carbon
+nanotubes during the oxidizing action of H2SO4 and HNO3 are presented. The
+process conditions used have been chosen so as to avoid any significant damage
+to the nanotube structure. The type and level of functionalization, the
+location of the grafted functions on the surface of the nanotube and the
+changes in morphological characteristics of the samples were examined by using
+a wide and complementary range of analytical techniques. We propose an
+explanation for the differences in the oxidizing action of sulfuric and nitric
+acids. The combined results allow us to suggest possible reaction mechanisms
+that occur on the surface of the nanotube.",2111.07623v1
+2022-01-08,Electronic Defects in Metal Oxide Photocatalysts,"A deep understanding of defects is essential for the optimisation of
+materials for solar energy conversion. This is particularly true for metal
+oxide photo(electro)catalysts, which typically feature high concentrations of
+charged point defects that are electronically active. In photovoltaic
+materials, except for selected dopants, defects are considered detrimental and
+should be eliminated to minimise charge recombination. However, photocatalysis
+is a more complex process where defects can play an active role, for example,
+by stabilising charge separation and mediating rate-limiting catalytic steps.
+Here, we review the behaviour of electronic defects in metal oxides, paying
+special attention to the principles underpinning the formation and function of
+trapped charges in the form of polarons. We focus on how defects alter the
+electronic structure, statically or transiently upon illumination, and discuss
+the implications of such changes in light-driven catalytic reactions. Finally,
+we consider the applicability of lessons learned from oxide defect chemistry to
+new photocatalysts based on carbon nitrides, polymers and metal halide
+perovskites.",2201.02808v1
+2022-01-31,Photocatalytic water oxidation on SrTiO$_3$ [001] surfaces,"SrTiO$_3$ is a highly efficient photocatalyst for the overall water splitting
+reaction under UV irradiation. However, an atomic-level understanding of the
+active surface sites responsible for the oxidation and reduction reactions is
+still lacking. Here we present a unified experimental and computational account
+of the photocatalytic activity at the SrO- and TiO$_2$- terminations of
+aqueous-solvated [001] SrTiO$_3$. Our experimental findings show that the
+overall water-splitting reaction proceeds on the SrTiO$_3$ surface only when
+the two terminations are simultaneously exposed to water. Our simulations
+explain this, showing that the photogenerated hole-driven oxidation primarily
+occurs at SrO surfaces in a sequence of four single hole transfer reactions,
+while the TiO$_2$ termination effects the crucial band alignment of the
+photocatalyst relative to the water oxidation potential. The present work
+elucidates the interdependence of the two chemical terminations of SrTiO$_3$
+surfaces, and has consequent implications for maximizing sustainable
+solar-driven water splitting.",2201.13443v1
+2022-02-03,Atomistic Engineering of Phonons in Functional Oxide Heterostructures,"Engineering of phonons, i.e., collective lattice vibrations in crystals, is
+essential for manipulating physical properties of materials such as thermal
+transport, electron-phonon interaction, confinement of lattice vibration, and
+optical polarization. Most approaches to phonon-engineering have been largely
+limited to the high-quality heterostructures of typical semiconductors. Yet,
+artificial engineering of phonons in a variety of materials with functional
+properties, such as complex oxides, will yield unprecedented applications of
+coherent tunable phonons in future quantum acoustic devices. In this study, we
+demonstrate artificial engineering of phonons in the atomic-scale SrRuO3/SrTiO3
+superlattices, wherein tunable phonon modes were observed via confocal Raman
+spectroscopy. In particular, the coherent superlattices led to the backfolding
+of acoustic phonon dispersion, resulting in zone-folded acoustic phonons in the
+THz frequency domain. We could further fine-tune the frequencies from 1 to 2
+THz via atomic-scale precision thickness control. In addition, we observed a
+polar optical phonon originating from the local inversion symmetry breaking in
+the artificial oxide superlattices, exhibiting emergent functionality. Our
+approach of atomic-scale heterostructuring of complex oxides will vastly expand
+material systems for quantum acoustic devices, especially with the viability of
+functionality integration.",2202.01450v1
+2022-02-12,Theoretical investigation of vacancy related defects at 4H-SiC(000$\bar{1}$)/SiO$_2$ interface after wet oxidation,"The stability and formation mechanism of the defects relevant to silicon and
+carbon vacancies at the 4H-SiC(000$\bar{1}$)/SiO$_2$ interface after wet
+oxidation are investigated by first-principles calculation based on the density
+functional theory. The difference in the total energy of the defects agrees
+with the experimental results concerning the dencity of defects. We found that
+the characteristic behaviors of the generation of defects are explained by the
+positions of vacancies and antisites in the SiC(000$\bar{1}$) substrate and
+that the formation of silicon and carbon vacancies is relevant to the
+generation mechanism of defects. The generation of silicon and carbon vacancies
+is attributed to the termination of dangling bonds by H atoms introduced by wet
+oxidation, resulting in generation of carbon-antisite--carbon-vacancy and
+divacancies defects in wet oxidation.",2202.06067v1
+2022-02-13,Kinetic Monte Carlo modelling of Helium Bubble Nucleation onto Oxides in the Fe-Ti-Y-O System,"A Kinetic Monte Carlo (KMC) model was created to simulate the insertion of
+transmutation He atoms into nanostructured ferritic alloys (NFAs) under neutron
+irradiation. Interstitial He atoms migrate through the NFA until becoming
+trapped in bubbles of other He atoms and vacancies created from irradiation.
+The Y-Ti-O nano-oxides in the NFAs were found to be effective in capturing
+these He atoms and preventing bubbles from forming at the grain boundary and
+appear to replicate the characteristics (size and number density) observed in
+other experiments. The bubbles were found to prefer the <111> oxide interface
+as a nucleation site and the stable bubbles have a He/Vac ratio between 1.3 and
+1.8 He/Vac. The influence of He bubbles on the segregation of solutes to the
+grain boundaries or on the stability of the nano-oxides were negligible.",2202.06189v1
+2022-03-10,Electric Double Layer at the Metal-Oxide/Electrolyte Interface,"Metal-oxide surfaces act as both Br{\o}nsted acids and bases, which allows
+the exchange of protons with the electrolyte solution and generates either
+positive or negative proton charges depending on the environmental pH. These
+interfacial proton charges are then compensated by counter-ions from the
+electrolyte solution, which leads to the formation of the electric double layer
+(EDL). Because the EDL plays a crucial role in electrochemistry, geochemistry
+and colloid science, understanding the structure-property relationship of the
+EDL in metal-oxide systems from both experimental and theoretical approaches is
+necessary. This chapter focuses on the physical chemistry of the protonic
+double layer at the metal-oxide/electrolyte interface. In particular,
+determinations of the EDL capacitance and the double-layer potential from
+potentiometric titration experiments, electrochemical methods,
+surface-sensitive vibrational spectroscopy and X-ray photoelectron spectroscopy
+are summarized. This is followed by discussions from the atomistic modelling
+aspect of the EDL, with an emphasis on the density-functional theory-based
+molecular dynamics simulations. A conclusion and outlook for future works on
+this topic are also given.",2203.05486v1
+2022-05-05,Light absorption and emission by defects in doped nickel oxide,"Nickel oxide is a versatile p-type semiconducting oxide with many
+applications in opto-electronic devices, but high doping concentrations are
+often required to achieve necessary electrical conductivity. In contrast to
+many other transparent oxide semiconductors, even moderate levels of doping of
+NiO can lead to significant optical absorption in the visible spectral range,
+limiting the application range of the material. This correlation has been
+reported extensively in literature, but its origin has been unknown until now.
+This work combines experimental data on optical properties from a variety of
+NiO samples with results from hybrid density functional theory calculations. It
+shows that strong electron-phonon interaction leads to a significant blue shift
+(0.6-1 eV) of electronic transitions from the valence band maximum to defect
+states by light absorption with respect to the thermodynamic charge transition
+levels. This essentially renders NiO a narrow-gap semiconductor by defect band
+formation already at moderate doping levels, with strong light absorption for
+photon energies of approximately 1 eV. The calculations are also shown to be
+fully consistent with experimental data on defect-related light emission in
+NiO.",2205.02606v1
+2022-05-06,Lattice dynamical properties of antiferromagnetic oxides calculated using self-consistent extended Hubbard functional method,"We study the lattice dynamics of antiferromagnetic transition-metal oxides by
+using self-consistent Hubbard functionals. We calculate the ground states of
+the oxides with the on-site and intersite Hubbard interactions determined
+self-consistently within the framework of density functional theory. The
+on-site and intersite Hubbard terms fix the errors associated with the electron
+self-interaction in the local and semilocal functionals. Inclusion of the
+intersite Hubbard terms in addition to the on-site Hubbard terms produces
+accurate phonon dispersion of the transition-metal oxides. Calculated Born
+effective charges and high-frequency dielectric constants are in good agreement
+with experiment. Our study provides a computationally inexpensive and accurate
+set of first-principles calculations for strongly-correlated materials and
+related phenomena.",2205.02972v1
+2022-07-09,Near-Infrared plasmon induced hot electron extraction evidence in an indium tin oxide nanoparticle / monolayer molybdenum disulphide heterostructure,"In this work, we observe plasmon induced hot electron extraction in a
+heterojunction between indium tin oxide nanocrystals and monolayer molybdenum
+disulphide. We study the sample with ultrafast differential transmission
+exciting the sample at 1750 nm where the intense localized plasmon surface
+resonance of the indium tin oxide nanocrystals is and where the monolayer
+molybdenum disulphide does not absorb light. With the excitation at 1750 nm we
+observe the excitonic features of molybdenum disulphide in the visible range,
+close to the exciton of molybdenum disulphide. Such phenomenon can be ascribed
+to a charge transfer between indium tin oxide nanocrystals and monolayer
+molybdenum disulphide upon plasmon excitation. These results are a first step
+towards the implementation of near infrared plasmonic materials for
+photoconversion.",2207.04195v2
+2022-07-26,$Ab$ $initio$ material design of Ag-based oxides for high-$T_c$ superconductor,"We propose silver-based oxides with layered perovskite structure as
+candidates of exhibiting intriguing feature of strongly correlated electrons.
+The compounds show unique covalence between Ag d and O p orbitals with the
+strong electron correlation of their antibonding orbital similar to the copper
+oxide high-temperature superconductors, but stronger covalency and slightly
+smaller correlation strength. We examine $A_2$AgO$_2X_2$ with $A$ =Sr and Ba
+and $X$ =F, I and Cl in detail. Among them, Sr$_2$AgO$_2$F$_2$ has the largest
+effective onsite Coulomb repulsion and shows an antiferromagnetic insulating
+ground state, which competes with correlated metals. It offers features both
+similar and distinct from the copper oxides, and paves a new route. The
+possibility of superconductivity in doped systems is discussed.",2207.12595v1
+2022-09-10,Visible Light-Driven C-C Coupling Reaction of Terminal Alkynes at Atmospheric Temperature and Pressure Reaction Conditions using Hybrid Cu2O-Pd Nanostructures,"Carbon-carbon (C-C) coupling reactions are widely used reactions in the
+production of fine chemicals, agrochemicals, and pharmaceuticals. In our recent
+contribution (Green Chemistry, 2019, 21, 5284-5290), cuprous oxide (Cu2O)
+nanospheres are shown to be efficient catalysts for C-C coupling reactions of
+terminal alkynes such as phenylacetylene. Specifically, Cu2O nanospheres are
+shown to successfully catalyze oxidative C-C homocoupling reaction of
+phenylacetylene to form a coupling product, diphenyl diacetylene (DPDA).
+However, these Cu2O nanocatalyst requires a relatively high temperature of ~110
+0C. Herein, we report that photocatalysts built on hybrid palladium
+nanoclusters decorated on Cu2O (i.e., Cu2O-Pd) can utilize visible light as
+energy input and successfully catalyze oxidative homocoupling of
+phenylacetylene at atmospheric temperature and pressure reaction condition.
+This was displayed by the comparison of oxidative homocoupling reactions both
+in the presence and without the presence of visible light. Our findings
+indicate that photocatalysts through Cu2O-Pd nanospheres present to be a
+logical substitute, moving toward more efficient and sustainable industrial
+processes.",2209.04568v1
+2022-09-20,Stabilizing polar phases in binary metal oxides by hole doping,"The recent observation of ferroelectricity in the metastable phases of binary
+metal oxides, such as HfO2, ZrO2, Hf0.5Zr0.5O2, and Ga2O3, has garnered a lot
+of attention. These metastable ferroelectric phases are typically stabilized
+through epitaxial growth, alloying, or defect engineering. Here, we propose
+hole doping plays a key role in stabilizing the polar phases in binary metal
+oxides. Using first-principles density-functional-theory calculations, we show
+that holes in these oxides mainly occupy one of the two oxygen sublattices.
+This hole localization, which is more pronounced in the polar phase than in the
+nonpolar phase, lowers the electrostatic energy of the system, and makes the
+polar phase more stable at sufficiently large concentrations. We demonstrate
+that this electrostatic mechanism is responsible for stabilization of the
+ferroelectric phase of HfO2 aliovalently doped with elements that introduce
+holes to the system, such as La and N. Finally, we show that the spontaneous
+polarization in HfO2 is robust to hole doping, and a large polarization
+persists even under a high concentration of holes.",2209.09436v3
+2022-09-29,Emergent topological states via digital (001) oxide superlattices,"Oxide heterostructures exhibit many intriguing properties. Here we provide
+design principles for inducing multiple topological states in (001)
+($AM$O$_3$)$_1$/($AM'$O$_3$)$_1$ oxide superlattices. Aided by first-principles
+calculations and model analysis, we show that a (Sr$M$O3)$_1$/(Sr$M'$O$_3$)$_1$
+superlattice ($M$ = Nb, Ta and $M'$ = Rh, Ir) is a strong topological insulator
+with $Z_2$ index (1;001). More remarkably, a (SrMoO3)$_1$/(SrIrO3)$_1$
+superlattice exhibits multiple coexisting topological insulator (TI) and
+topological Dirac semi-metal (TDS) states. The TDS state has a pair of type-II
+Dirac points near the Fermi level and symmetry-protected Dirac node lines. The
+surface TDS Dirac cone is sandwiched by two surface TI Dirac cones in the
+energy-momentum space. The non-trivial topological properties arise from the
+band inversion between $d$ orbitals of two dissimilar transition metal atoms
+and a particular parity property of (001) superlattice geometry. Our work
+demonstrates how to induce nontrivial topological states in (001) perovskite
+oxide heterostructures by rational design.",2209.14674v1
+2022-10-27,Characterization of AlW oxide coatings on aluminum formed by pulsed direct current plasma electrolytic oxidation at ultralow duty cycles,"The growth of thin oxide coatings on the aluminum substrate in water-based
+sodium tungstate electrolyte by plasma electrolytic oxidation (PEO) is
+discussed and experimentally illustrated. The growth is carried out using a
+distinctive ultra-low duty cycle pulsed direct current (DC) power supply.
+During the PEO processing elements present in micro-discharges are identified
+using standard optical emission spectroscopy (OES) technique. The spectral line
+shape analysis of the first two hydrogen Balmer lines shows the presence of two
+types of micro-discharges. Obtained coatings are also characterized with
+respect to their morphology and chemical and phase composition. It is shown
+that coatings are composed of Al, O, and W, featuring low roughness and
+porosity. Partial crystallization of the coatings resulted in identification of
+WO3, W3O8, and gamma-Al2O3 crystalline phases.",2210.15719v1
+2022-12-20,Engineering superconducting properties of multiferroic copper oxide heterostructures,"Oxide heterostructures have repeatedly been shown to display apical
+properties at the interfaces, some of which favorable to the formation of
+two-dimensional electron systems, as well as high transition temperature
+superconductivity. In this study, we propose a novel heterostructure to
+potentially achieve near room-temperature superconductivity, via the carrier
+injection in cuprate interfaces with ferro-electrics. Using a digital design
+approach guided by density-functional theory, the systems of XTiO3/XCuO3/XTiO3
+are thoroughly examined, confirming the formation of a two-dimensional electron
+gas at the cuprous oxide interface. Via the manipulation of lattice parameters,
+the key ingredients for two-dimensional electron gas formation is explored. We
+apply cluster dynamical mean-field theory on the cuprous oxide plane and probe
+the superconducting properties of the system XTiO3/XCuO3/XTiO3 . As a result,
+we see a marked increase of superconducting ordering parameter near the fully
+occupied regime, a known marker for the superconducting transition temperature.",2212.10109v1
+2023-01-16,The fate of water in hydrogen-based iron oxide reduction,"Gas-solid reactions are cornerstones of many catalytic and redox processes
+that will underpin the energy and sustainability transition. The specific case
+of hydrogen-based iron oxide reduction is the foundation to render the global
+steel industry fossil-free, an essential target as iron production is the
+largest single industrial emitter of carbon dioxide. Our perception of
+gas-solid reactions has not only been limited by the availability of
+state-of-the-art techniques which can delve into the reacted solids in great
+structural and chemical detail, but we continue to miss an important reaction
+partner that defines the thermodynamics and kinetics of gas phase reactions:
+the gas molecules. In this investigation, we use the latest development in
+cryogenic atom probe tomography to study the quasi in-situ evolution of gas
+phase heavy water at iron-iron oxide interfaces resulting from the direct
+reduction of iron oxide by deuterium gas at 700{\deg}C. The findings provide
+new insights into the formation kinetics and location of water formed during
+hydrogen-based reduction of FeO, an its interaction with the ongoing redox
+reaction.",2301.06391v1
+2023-03-15,Artificial ageing of thin films of the indium-free transparent conducting oxide SrVO3,"SrVO3 (SVO) is a prospective candidate to replace the conventional
+indium-tin-oxide (ITO) among the new transparent conducting oxide (TCO)
+generation. In this study, the structural, electrical, and optical properties
+of SVO thin films, both epitaxial and polycrystalline, are determined during
+and after heat treatments in the 150-250 {\deg}C range and under ambient
+environment in order to explore the chemical stability of this material. The
+use of these relatively low temperatures speeds up the natural ageing of the
+films, and allows to follow the evolution of their related properties. The
+combination of techniques rather sensitive to the film surface and of
+techniques sampling the film volume will emphasize the presence of a surface
+oxidation evolving in time at low annealing temperatures, whereas the
+perovskite phase is destroyed throughout the film for treatments above 200
+{\deg}C. The present study is designed to understand the thermal degradation
+and long-term stability issues of vanadate-based TCOs, and to identify
+technologically viable solutions for the application of this group as new TCOs.",2303.08449v1
+2023-04-27,Comparison of Raman imaging assessment methods in phase determination and stress analysis of zirconium oxide layer,"This work describes Raman imaging and its data evaluation methods by using
+the softwares original features: built-in fitting function and K-means cluster
+analysis KMC followed by fitting in an external environment. For the first
+time, these methods were compared in terms of their principles, limitations,
+versatility, and process duration. The performed analysis showed the
+indispensability of Raman imaging in terms of phase distribution, phase content
+calculation, and stress determination. Zirconium oxide formed on different
+zirconium alloys under various oxidation conditions was selected as an
+exemplary material for this analysis. The reason for the material choice is
+that it is an excellent example of the application of this type of Raman
+analysis since both phase distribution and stress analysis in zirconium oxide
+are of crucial importance for the development of zirconium alloys, especially
+for nuclear applications. The juxtaposition of the results showed advantages
+and limitations of both procedures allowing a definition of the criteria for
+selecting the evaluation method for different applications.",2304.13982v1
+2023-07-04,"Disentangling the Role of Electrons and Phonons in the Photoinduced CO Desorption and CO Oxidation on (O,CO)-Ru(0001)","The role played by electronic and phononic excitations in the femtosecond
+laser induced desorption and oxidation of CO coadsorbed with O on Ru(0001) is
+investigated using ab initio molecular dynamics with electronic friction. To
+this aim, simulations that account for both kind of excitations and that only
+consider electronic excitations are performed. Results for three different
+surface coverages are obtained. We unequivocally demonstrate that CO desorption
+is governed by phononic excitations. In the case of oxidation the low
+statistics does not allow to give a categorical answer. However, the analysis
+of the adsorbates kinetic energy gain and displacements strongly suggest that
+phononic excitations and surface distortion also play an important role in the
+oxidation process.",2307.01553v1
+2023-07-06,Boron-doped graphene -- DFT study of the role of dopant concentration and oxidation on sodium and aluminium storage applications,"Graphene is thought to be a promising materials for many applications.
+However, pristine graphene is not suitable for most electrochemical devices,
+where defect engineering is crucial for its performance. We demonstrate how
+boron doping of graphene can alter its reactivity, electrical conductivity and
+potential application for sodium and aluminium storage, with the emphasis on
+novel metal-ion batteries. Using DFT calculations, we investigate both the
+influence of boron concentration and the oxidation of the material, on the
+mentioned properties. It is demonstrated that the presence of boron in graphene
+increases its reactivity towards atomic hydrogen and oxygen-containing species,
+in other words, it makes B-doped graphene more prone to oxidation.
+Additionally, the presence of these surface functional groups significantly
+alters the type and strength of the interaction of Na and Al with the given
+materials. Boron-doping and oxidation of graphene is found to increase Na
+storage capacity of graphene by the factor of up to 4.",2307.02885v1
+2023-07-11,Stabilization of Ferroelectric Hf0.5Zr0.5O2 Epitaxial Films via Monolayer Reconstruction Driven by Interfacial Redox Reaction,"The binary fluorite oxide Hf0.5Zr0.5O2 tends to grab a significant amount of
+notice due to the distinct and superior ferroelectricity found in its
+metastable phase. Stabilizing the metastable ferroelectric phase and
+delineating the underlying growth mechanism, however, are still challenging.
+Recent discoveries of metastable ferroelectric Hf0.5Zr0.5O2 epitaxially grown
+on structurally dissimilar perovskite oxides have triggered intensive
+investigations on the ferroelectricity in materials that are nonpolar in bulk
+form. Nonetheless, the growth mechanism for the unique fluorite/perovskite
+heterostructures has yet to be fully explored. Here we show that the metastable
+ferroelectric Hf0.5Zr0.5O2 films can be stabilized even on a
+one-unit-cell-thick perovskite La0.67Sr0.33MnO3 buffer layer. In collaboration
+with scanning transmittance electron microscopy (STEM) based characterizations,
+we show that monolayer reconstruction driven by interfacial redox reactions
+plays a vital role in the formation of a unique heterointerface between the two
+structurally dissimilar oxides, providing the template monolayer that
+facilitates the epitaxial growth of the metastable HZO films. Our findings
+offer significant insights into the stabilization mechanism of the
+ferroelectric Hf0.5Zr0.5O2, and this mechanism could be extended for exploring
+functional metastable phases of various metal oxides.",2307.05346v1
+2023-08-27,Reconstruction changes drive surface diffusion and determine the flatness of oxide surfaces,"Surface diffusion on metal oxides is key in many areas of materials
+technology, yet it has been scarcely explored at the atomic scale. This work
+provides phenomenological insights from scanning tunneling microscopy on the
+link between surface diffusion, surface atomic structure, and oxygen chemical
+potential based on three model oxide surfaces: Fe$_2$O$_3(1\overline{1}02)$,
+La$_{1-x}$Sr$_x$MnO$_3$(110), and In$_2$O$_3$(111). In all instances, changing
+the oxygen chemical potential used for annealing stabilizes reconstructions of
+different compositions while promoting the flattening of the surface morphology
+-- a sign of enhanced surface diffusion. It is argued that thermodynamics,
+rather than kinetics, rules surface diffusion under these conditions: The
+composition change of the surface reconstructions formed at differently
+oxidizing conditions drives mass transport across the surface.",2308.14043v1
+2023-09-08,Prediction of the Cu Oxidation State from EELS and XAS Spectra Using Supervised Machine Learning,"Electron energy loss spectroscopy (EELS) and X-ray absorption spectroscopy
+(XAS) provide detailed information about bonding, distributions and locations
+of atoms, and their coordination numbers and oxidation states. However,
+analysis of XAS/EELS data often relies on matching an unknown experimental
+sample to a series of simulated or experimental standard samples. This limits
+analysis throughput and the ability to extract quantitative information from a
+sample. In this work, we have trained a random forest model capable of
+predicting the oxidation state of copper based on its L-edge spectrum. Our
+model attains an $R^2$ score of 0.89 and a root mean square valence error of
+0.21 on simulated data. It has also successfully predicted experimental L-edge
+EELS spectra taken in this work and XAS spectra extracted from the literature.
+We further demonstrate the utility of this model by predicting simulated and
+experimental spectra of mixed valence samples generated by this work. This
+model can be integrated into a real time EELS/XAS analysis pipeline on mixtures
+of copper containing materials of unknown composition and oxidation state. By
+expanding the training data, this methodology can be extended to data-driven
+spectral analysis of a broad range of materials.",2309.04067v1
+2023-09-18,Disassembling one-dimensional chains in molybdenum oxides,"The dimensionality of quantum materials strongly affects their physical
+properties. Although many emergent phenomena, such as charge-density wave and
+Luttinger liquid behavior, are well understood in one-dimensional (1D) systems,
+the generalization to explore them in higher dimensional systems is still a
+challenging task. In this study, we aim to bridge this gap by systematically
+investigating the crystal and electronic structures of molybdenum-oxide family
+compounds, where the contexture of 1D chains facilitates rich emergent
+properties. While the quasi-1D chains in these materials share general
+similarities, such as the motifs made up of MoO6 octahedrons, they exhibit vast
+complexity and remarkable tunability. We disassemble the 1D chains in
+molybdenum oxides with different dimensions and construct effective models to
+excellently fit their low-energy electronic structures obtained by ab initio
+calculations. Furthermore, we discuss the implications of such chains on other
+physical properties of the materials and the practical significance of the
+effective models. Our work establishes the molybdenum oxides as simple and
+tunable model systems for studying and manipulating the dimensionality in
+quantum systems.",2309.09729v1
+2023-09-19,Electronic Properties and Interlayer Interactions in Antimony Oxide Homo- and Heterobilayers,"Antimony shows promise as a two-dimensional (2D) mono-elemental crystal,
+referred to as antimonene. When exposed to ambient conditions, antimonene
+layers react with oxygen, forming new crystal structures, leading significant
+changes in electronic properties. These changes are influenced by the degree of
+oxidation. Utilizing Density Functional Theory (DFT) calculations, stable
+configurations of bilayer antimony oxide and their corresponding electronic
+properties are studied. Additionally, different stacking arrangements and their
+effects on the physical properties of the materials are investigated.
+Furthermore, the analysis encompasses strain-free hetero-bilayers containing
+both pristine and oxidized antimonene layers, aiming to understand the
+interplay between these materials and their collective impact on the bilayer
+properties. Our results provide insight into how the properties of
+antimony-based bilayer structures can be modified by adjusting stoichiometry
+and stacking configurations.",2309.10653v2
+2024-01-29,Anomalous thermal oxidation of gadolinium thin films deposited on silicon by high pressure sputtering,"Thin gadolinium metallic layers were deposited by high-pressure sputtering in
+pure Ar atmosphere. Subsequently, in situ thermal oxidation was performed at
+temperatures ranging from 150 to 750 $^\circ$C. At an oxidation temperature of
+500 $^\circ$C the films show a transition from monoclinic structure to a
+mixture of monoclinic and cubic. Regrowth of interfacial SiO$_x$ is observed as
+temperature is increased, up to 1.6 nm for 750 $^\circ$C. This temperature
+yields the lowest interface trap density, 4e10 eV$^{-1}$ cm$^{-2}$, but the
+effective permittivity of the resulting dielectric is only 7.4. The reason of
+this low value is found on the oxidation mechanism, which yields a surface with
+located bumps. These bumps increase the average thickness, thus reducing the
+capacitance and therefore the calculated permittivity.",2402.10925v1
+2024-02-16,Standardization of chemically selective atomic force microscopy for metal-oxide surfaces,"The complex atomic structures and defects of metal-oxide surfaces are vital
+for a variety of applications in material science and chemistry. While scanning
+probe microscopy allows accessing atomic-scale structures in real space,
+elemental discrimination and defect characterization usually rely on indirect
+assumptions and extensive theoretical modelling. By investigating a variety of
+different sample systems with increasing structural complexity and inherent
+defects, we demonstrate that noncontact atomic force microscopy with an
+O-terminated copper tip allows imaging metal-oxide surfaces with a clear
+elemental contrast. This universal approach provides not only immediate access
+to the metal- and oxygen sub-lattices, but also to the chemical and structural
+configuration of atomic-scale defect structures. The observed contrast can be
+explained by purely electrostatic interactions between the negatively charged
+tip apex and the strongly varying electrostatic potential between metal- and
+oxygen surface sites. These results offer a standardized methodology for the
+direct structural characterization of even most-complex metal-oxide surfaces,
+which is highly relevant for a fundamental understanding of atomic-scale
+processes on these material systems.",2402.11045v1
+2024-03-19,Micro-Raman spectroscopy of graphene defects and tracing the oxidation process caused by UV exposure,"Raman spectroscopy is one of the widely used methods in the analysis of
+various samples including carbon-based materials. This study aimed to identify
+the number of layers and defects in graphene using micro-Raman spectroscopy.
+More specifically, the study examined tracing the oxidation process of graphene
+under UV exposure. Investigation of the effect of the power density of the
+Raman excitation laser reveals a linear dependence between the ratio of I2D/IG
+and the power density of the excitation laser. Also, the absence of peak D due
+to the increase in power density provides evidence for the non-destructive
+nature of micro-Raman spectroscopy. Given the value of I2D/IG, one of the
+parameters for determining the number of layers in graphene which has reached
+1.39 at the edge, the findings indicate the possibility of an edge fold of
+single-layer graphene. During the oxidation process, the intensity and position
+of the D peak increase as a function of exposure time. Alterations in the
+graphene Raman spectrum, comprising the disappearance of the 2D peak and the
+appearance of the D peak, trace and confirm the oxidation process of the
+sample.",2403.13191v1
+2005-06-22,Superconductivity and Cobalt Oxidation State in Metastable Na(x)CoO(2-delta)*yH2O (x ~ 1/3; y ~ 4x),"We report the synthesis and superconducting properties of a metastable form
+of the known superconductor NaxCoO2*yH2O (x ~ 1/3, y ~ 4x). Instead of using
+the conventional bromine-acetonitrile mixture for sodium deintercalation, we
+use an aqueous bromine solution. Using this method, we oxidize the sample to a
+point that the sodium cobaltate becomes unstable, leading to formation of other
+products if not controlled. This compound has the same structure as the
+reported superconductor, yet it exhibits a systematic variation of the
+superconducting transition temperature (Tc) as a function of time. Immediately
+after synthesis, this compound is not a superconductor, even though it contains
+appropriate amounts of sodium and water. The samples become superconducting
+with low Tc values after ~ 90 h. Tc continually increases until it reaches a
+maximum value (4.5 K) after about 260 h. Then Tc drops drastically, becoming
+non-superconducting approximately 100 h later. Corresponding time-dependent
+neutron powder diffraction data shows that the changes in superconductivity
+exhibited by the metastable cobaltate correspond to slow formation of oxygen
+vacancies in the CoO2 layers. In effect, the formation of these defects
+continually reduces the cobalt oxidation state causing the sample to evolve
+through its superconducting life cycle. Thus, the dome-shaped superconducting
+phase diagram is mapped as a function of cobalt oxidation state using a single
+sample. The width of this dome based on the formal oxidation state of cobalt is
+very narrow - approximately 0.1 valence units wide. Interestingly, the maximum
+Tc in NaxCoO2*yH2O occurs when the cobalt oxidation state is near 3.5. Thus, we
+speculate that the maximum Tc occurs near the charge ordered insulating state
+that correlates with the average cobalt oxidation state of 3.5.",0506549v1
+2010-10-04,Doping Dependence of Thermal Oxidation on n-type 4H-SiC,"The doping dependence of dry thermal oxidation rates in n-type 4H-SiC was
+investigated. The oxidation was performed in the temperature range 1000C to
+1200C for samples with nitrogen doping in the range of 6.5e15/cm3 to
+9.3e18/cm3, showing a clear doping dependence. Samples with higher doping
+concentrations displayed higher oxidation rates. The results were interpreted
+using a modified Deal-Grove model. Linear and parabolic rate constants and
+activation energies were extracted. Increasing nitrogen led to an increase in
+linear rate constant pre-exponential factor from 10-6m/s to 10-2m/s and the
+parabolic rate constant pre-exponential factor from 10e9m2/s to 10e6m2/s. The
+increase in linear rate constant was attributed to defects from doping-induced
+lattice mismatch, which tend to be more reactive than bulk crystal regions. The
+increase in the diffusion-limited parabolic rate constant was attributed to
+degradation in oxide quality originating from the doping-induced lattice
+mismatch. This degradation was confirmed by the observation of a decrease in
+optical density of the grown oxide films from 1.4 to 1.24. The linear
+activation energy varied from 1.6eV to 2.8eV, while the parabolic activation
+energy varied from 2.7eV to 3.3eV, increasing with doping concentration. These
+increased activation energies were attributed to higher nitrogen content,
+leading to an increase in effective bond energy stemming from the difference in
+C-Si (2.82eV) and Si-N (4.26eV) binding energies. This work provides crucial
+information in the engineering of SiO2 dielectrics for SiC MOS structures,
+which typically involve regions of very different doping concentrations, and
+suggests that thermal oxidation at high doping concentrations in SiC may be
+defect mediated.",1010.0473v1
+2015-04-22,Extreme mobility enhancement of two-dimensional electron gases at oxide interfaces via charge transfer induced modulation doping,"The discovery of two-dimensional electron gases (2DEGs) at the interface
+between two insulating complex oxides, such as LaAlO3 (LAO) or gamma-Al2O3
+(GAO) epitaxially grown on SrTiO3 (STO) 1,2, provides an opportunity for
+developing all-oxide electronic devices3,4. These 2DEGs at complex oxide
+interfaces involve many-body interactions and give rise to a rich set of
+phenomena5, for example, superconductivity6, magnetism7,8, tunable
+metal-insulator transitions9, and phase separation10. However, large
+enhancement of the interfacial electron mobility remains a major and
+long-standing challenge for fundamental as well as applied research of complex
+oxides11-15. Here, we inserted a single unit cell insulating layer of polar
+La1-xSrxMnO3 (x=0, 1/8, and 1/3) at the interface between disordered LaAlO3 and
+crystalline SrTiO3 created at room temperature. We find that the electron
+mobility of the interfacial 2DEG is enhanced by more than two orders of
+magnitude. Our in-situ and resonant x-ray spectroscopic in addition to
+transmission electron microscopy results indicate that the manganite layer
+undergoes unambiguous electronic reconstruction and leads to modulation doping
+of such atomically engineered complex oxide heterointerfaces. At low
+temperatures, the modulation-doped 2DEG exhibits clear Shubnikov-de Haas
+oscillations and the initial manifestation of the quantum Hall effect,
+demonstrating an unprecedented high-mobility and low electron density oxide
+2DEG system. These findings open new avenues for oxide electronics.",1504.05986v1
+2015-07-31,Calibrating transition metal energy levels and oxygen bands in first principles calculations: accurate prediction of redox potentials and charge transfer in lithium transition metal oxides,"Transition metal (TM) oxides play an increasingly important role in
+technology today including applications such as catalysis, solar energy
+harvesting, and energy storage. In many of these applications, the details of
+their electronic structure near the Fermi level are critically important for
+their properties. We propose a first-principles based computational methodology
+for the accurate prediction of oxygen charge transfer in TM oxides and lithium
+TM (Li-TM) oxides. To obtain accurate electronic structures, the
+Heyd-Scuseria-Ernzerhof (HSE06) hybrid functional is adopted and the amount of
+exact Hartree-Fock exchange (mixing parameter) is adjusted to reproduce
+reference band gaps. We show that the HSE06 functional with optimal mixing
+parameter yields not only improved electronic densities of states but also
+better energetics (Li-intercalation voltages) for LiCoO2 and LiNiO2 as compared
+to GGA, GGA+U and standard HSE06. We find that the optimal mixing parameters
+for TM oxides are system-specific and correlate with the covalency (ionicity)
+of the TM species. Strong covalent (ionic) nature of TM-O bonding leads to
+lower (higher) optimal mixing parameters. We find that optimized HSE06
+functionals predict stronger hybridization of the Co 3d and O 2p orbitals than
+GGA, resulting in a greater contribution from oxygen states to charge
+compensation upon delithiation in LiCoO2. We also find that the band gaps of
+Li-TM oxides increase linearly with the mixing parameter, enabling the
+straightforward determination of optimal mixing parameters based on GGA
+({\alpha} = 0.0) and HSE06 ({\alpha} = 0.25) calculations. Our results also
+show that G0W0@GGA+U band gaps of TM oxides (MO, M = Mn, Co, Ni) and LiCoO2
+agree well with experimental references, suggesting that G0W0 calculations can
+be used as a reference for the calibration of the mixing parameter in case no
+experimental band gap has been reported.",1507.08768v1
+2019-09-02,Resolving the Nucleation Stage in Atomic Layer Deposition of Hafnium Oxide on Graphene,"The integration of two-dimensional (2D) materials with functional non-2D
+materials such as metal oxides is of key importance for many applications, but
+underlying mechanisms for such non-2D/2D interfacing remain largely elusive at
+the atomic scale. To address this, we here investigate the nucleation stage in
+atomic layer deposition (ALD) of the important metal oxide HfO2 on chemical
+vapor deposited graphene using atomically resolved and element specific
+scanning transmission electron microscopy (STEM). To avoid any deleterious
+influence of polymer residues from pre-ALD graphene transfers we employ a
+substrate-assisted ALD process directly on the as grown graphene still
+remaining on its Cu growth catalyst support. Thereby we resolve at the atomic
+scale key factors governing the integration of non-2D metal oxides with 2D
+materials by ALD: Particular to our substrate-assisted ALD process we find a
+graphene-layer-dependent catalytic participation of the supporting Cu catalyst
+in the ALD process. We further confirm at high resolution the role of surface
+irregularities such as steps between graphene layers on oxide nucleation.
+Employing the energy transfer from the scanning electron beam to in situ
+crystallize the initially amorphous ALD HfO2 on graphene, we observe HfO2
+crystallization to non-equilibrium HfO2 polymorphs (cubic/tetragonal). Finally
+our data indicates a critical role of the graphene's atmospheric adventitious
+carbon contamination on the ALD process whereby this contamination acts as an
+unintentional seeding layer for metal oxide ALD nucleation on graphene under
+our conditions. As atmospheric adventitious carbon contamination is hard to
+avoid in any scalable 2D materials processing, this is a critical factor in ALD
+recipe development for 2D materials coating. Combined our work highlights
+several key mechanisms underlying scalable ALD oxide growth on 2D materials.",1909.00712v1
+2021-03-11,"A coupled model of episodic warming, oxidation and geochemical transitions on early Mars","Reconciling the geology of Mars with models of atmospheric evolution remains
+a major challenge. Martian geology is characterized by past evidence for
+episodic surface liquid water, and geochemistry indicating a slow and
+intermittent transition from wetter to drier and more oxidizing surface
+conditions. Here we present a new model incorporating randomized injection of
+reducing greenhouse gases and oxidation due to hydrogen escape, to investigate
+the conditions responsible for these diverse observations. We find that Mars
+could have transitioned repeatedly from reducing (H2-rich) to oxidizing
+(O2-rich) atmospheric conditions in its early history. Our model predicts a
+generally cold early Mars, with mean annual temperatures below 240 K. If peak
+reducing gas release rates and background CO2 levels are high enough, it
+nonetheless exhibits episodic warm intervals sufficient to degrade crater
+walls, form valley networks and create other fluvial/lacustrine features. Our
+model also predicts transient buildup of atmospheric O2, which can help explain
+the occurrence of oxidized mineral species such as manganese oxides at Gale
+Crater. We suggest that the apparent Noachian--Hesperian transition from
+phyllosilicate deposition to sulfate deposition around 3.5 billion years ago
+can be explained as a combined outcome of increasing planetary oxidation,
+decreasing groundwater availability and a waning bolide impactor flux, which
+dramatically slowed the remobilization and thermochemical destruction of
+surface sulfates. Ultimately, rapid and repeated variations in Mars' early
+climate and surface chemistry would have presented both challenges and
+opportunities for any emergent microbial life.",2103.06736v1
+2022-12-13,On the surface chemisorption of oxidizing fine iron particles: insights gained from molecular dynamics simulations,"Molecular dynamics (MD) simulations are performed to investigate the thermal
+and mass accommodation coefficients (TAC and MAC, respectively) for the
+combination of iron(-oxide) and air. The obtained values of TAC and MAC are
+then used in a point-particle Knudsen model to investigate the effect of
+chemisorption and the Knudsen transition regime on the combustion behavior of
+(fine) iron particles. The thermal accommodation for the interactions of
+$\mathrm{Fe}$ with $\mathrm{N_2}$ and $\mathrm{Fe_xO_y}$ with $\mathrm{O_2}$ is
+investigated for different surface temperatures, while the mass accommodation
+coefficient for iron(-oxide) with oxygen is investigated for different initial
+oxidation stages $Z_\mathrm{O}$, which represents the molar ratio of
+$\mathrm{O}/\left(\mathrm{O} + \mathrm{Fe}\right)$, and different surface
+temperatures. The MAC decreases fast from unity to 0.03 as $Z_\mathrm{O}$
+increases from 0 to 0.5 and then diminishes as $Z_\mathrm{O}$ further increases
+to 0.57. By incorporating the MD-informed accommodation coefficients into the
+single iron particle combustion model,a new temperature evolution for single
+iron particles is observed compared to results obtained with previously
+developed continuum models. Specifically, results of the present simulations
+show that the oxidation process continues after the particle reaching the peak
+temperature, while previous models predicting that the maximum temperature was
+attained when the particle is oxidized to $Z_\mathrm{O} = 0.5$. Since the rate
+of oxidation slows down as the MAC decreases with an increasing oxidation
+stage, the rate of heat loss exceeds the rate of heat release upon reaching the
+maximum temperature, while the particle is not yet oxidized to $Z_\mathrm{O} =
+0.5$. Finally, the effect of transition-regime heat and mass transfer on the
+combustion behavior of fine iron particles is investigated and discussed.",2212.06432v2
+2023-03-06,Ternary oxides of $\textit{s}$- and $\textit{p}$-block metals for photocatalytic solar-to-hydrogen conversion,"Oxides containing metals or metalloids from the {\it p}-block of the periodic
+table ({\it e.g.}, In, Sn, Sb, Pb, Bi) are of technological interest as
+transparent conductors and light absorbers for solar energy conversion due to
+the tunability of their electronic conductivity and optical absorption.
+Comparatively, these oxides have found limited applications in hydrogen
+photoelectrolysis primarily due to their high electronegativity, which impedes
+electron transfer for reducing protons into hydrogen. We have shown recently
+that inserting {\it s}-block cations into {\it p}-block metal oxides is
+effective at lowering electronegativities while affording further control of
+band gaps. Here, we explain the origins of this dual tunability by
+demonstrating the mediator role of {\it s}-block cations in modulating orbital
+hybridization while not contributing to frontier electronic states. From this
+result, we carry out a comprehensive computational study of 109 ternary oxides
+of {\it s}- and {\it p}-block metal elements as candidate photocatalysts for
+solar hydrogen generation. We downselect the most desirable materials using
+band gaps and band edges obtained from Hubbard-corrected density-functional
+theory with Hubbard parameters computed entirely from first principles,
+evaluate the stability of these oxides in aqueous conditions, and characterize
+experimentally four of the remaining materials, synthesized with high phase
+uniformity, to validate and further develop the computational models. We thus
+propose nine oxide semiconductors, including CsIn$_3$O$_5$, Sr$_2$In$_2$O$_5$,
+and KSbO$_2$ which, to the extent of our literature review, have not been
+previously considered as water-splitting photocatalysts.",2303.03332v2
+2023-04-12,Selective thermal evolution of native oxide layer in Nb and Nb3Sn-coated SRF grade Nb: An in-situ angular XPS study,"This contribution discusses the results of an in-situ angular XPS study on
+the thermal evolution of the native oxide layer on Nb3Sn and pure Nb. XPS data
+were recorded with conventional spectrometers using an AlK(alpha) X-ray source
+for spectra collected up to 600 C, and an MgK(Alpha) X-rays source for
+temperatures above 600 C. The effect of the thickness, composition, and thermal
+stability of that oxide layer is relevant to understanding the functional
+properties of superconducting radiofrequency (SRF) cavities used in particle
+accelerators. There is a consensus that oxide plays a role in surface
+resistance (Rs). The focus of this study is Nb3Sn, which is a promising
+material that is used in the manufacturing of superconducting radiofrequency
+(SRF) cavities as well as in quantum sensing, and pure Nb, which was included
+in the study for comparison. The thermal evolution of the oxide layer in these
+two materials is found to be quite different, which is ascribed to the
+influence of the Sn atom on the reactivity of the Nb atom in Nb3Sn films. Nb
+and Sn atoms in this intermetallic solid have different electronegativity, and
+the Sn atom can reduce electron density around neighbouring Nb atoms in the
+solid, thus reducing their reactivity for oxygen. This is shown in the
+thickness, composition, and thermal stability of the oxide layer formed on
+Nb3Sn. The XPS spectra were complemented by grazing incident XRD patterns
+collected using the ESRF synchrotron radiation facility. The results discussed
+herein shed light on oxide evolution in the Nb3Sn compound and guide its
+processing for potential applications of the Nb3Sn-based SRF cavities in
+accelerators and other superconducting devices.",2304.06112v1
+2023-12-10,Understanding muon diffusion in perovskite oxides below room temperature based on harmonic transition state theory,"In positive muon spin rotation and relaxation ($\mu^+$SR) spectroscopy,
+positive muons ($\mu^+$) implanted into solid oxides are conventionally treated
+as immobile spin-probes at interstitial sites below room temperature. This is
+because each $\mu^+$ is thought to be tightly bound to an oxygen atom in the
+host lattice to form a muonic analogue of the hydroxy group. On the basis of
+this concept, anomalies in $\mu^+$SR spectra observed in oxides have been
+attributed in most cases to the intrinsic properties of host materials. On the
+other hand, global $\mu^+$ diffusion with an activation energy of $\sim$0.1~eV
+has been reported in some chemically-substituted perovskite oxides at cryogenic
+temperatures, although the reason for the small activation energy despite the
+formation of the strong O$\mu$ bond has not yet been quantitatively understood.
+In this study, we investigated interstitial $\mu^+$ diffusion in the perovskite
+oxide lattice using KTaO$_3$ cubic perovskite as a model system. We used the
+$\mu^+$SR method and density functional theory calculations along with the
+harmonic transition state theory to study this phenomenon both experimentally
+and theoretically. Experimental activation energies for global $\mu^+$
+diffusion obtained below room temperature were less than a quarter of the
+calculated classical potential barrier height for a bottleneck $\mu^+$ transfer
+path. The reduction in the effective barrier height could be explained by the
+harmonic transition state theory with a zero-point energy correction; a
+significant difference in zero-point energies for $\mu^+$ at the positions in
+the O$\mu$ bonding equilibrium state and a bond-breaking transition state was
+the primary cause of the reduction. This suggests that the assumption of
+immobile $\mu^+$ in solid oxides is not always satisfied since such a
+significant decrease in diffusion barrier height can also occur in other
+oxides.",2312.05755v1
+2004-02-03,Aluminum Oxide Layers as Possible Components for Layered Tunnel Barriers,"We have studied transport properties of Nb/Al/AlOx/Nb tunnel junctions with
+ultrathin aluminum oxide layers formed by (i) thermal oxidation and (ii) plasma
+oxidation, before and after rapid thermal post-annealing of the completed
+structures at temperatures up to 550 deg C. Post-annealing at temperatures
+above 300 deg C results in a significant decrease of the tunneling conductance
+of thermally-grown barriers, while plasma-grown barriers start to change only
+at annealing temperatures above 450 deg C. Fitting the experimental I-V curves
+of the junctions using the results of the microscopic theory of direct
+tunneling shows that the annealing of thermally-grown oxides at temperatures
+above 300 deg C results in a substantial increase of their average tunnel
+barriers height, from ~1.8 eV to ~2.45 eV, versus the practically unchanged
+height of ~2.0 eV for plasma-grown layers. This difference, together with high
+endurance of annealed barriers under electric stress (breakdown field above 10
+MV/cm) may enable all-AlOx and SiO2/AlOx layered ""crested"" barriers for
+advanced floating-gate memory applications.",0402092v1
+2005-01-03,Density-functional theory study of the initial oxygen incorporation in Pd(111),"Pd(111) has recently been shown to exhibit a propensity to form a
+sub-nanometer thin surface oxide film already well before a full monolayer
+coverage of adsorbed O atoms is reached on the surface. Aiming at an
+atomic-scale understanding of this finding, we study the initial oxygen
+incorporation into the Pd(111) surface using density-functional theory. We find
+that oxygen incorporation into the sub-surface region starts at essentially the
+same coverage as formation of the surface oxide. This implies that the role of
+sub-surface oxygen should be considered as that of a metastable precursor in
+the oxidation process of the surface. The mechanisms found to play a role
+towards the ensuing stabilization of an ordered oxidic structure with a mixed
+on-surface/sub-surface site occupation follow a clear trend over the late 4d
+transition metal series, as seen by comparing our data to previously published
+studies concerned with oxide formation at the basal surface of Ru, Rh and Ag.
+The formation of a linearly aligned O-TM-O trilayered structure (TM = Ru, Rh,
+Pd, Ag), together with an efficient coupling to the underlying substrate seem
+to be key ingredients in this respect.",0501018v1
+2006-05-24,KrF pulsed laser deposition of chromium oxide thin films from Cr8O21 targets,"Chromium oxides, CrxOy, are of great interest due to the wide variety of
+their technological applications. Among them, CrO2 has been extensively
+investigated in recent years because it is an attractive compound to be used in
+spintronic heterostructures. However, its synthesis at low temperatures has
+been a difficult task due to the metastable nature of this oxide. This is
+indeed essential to ensure interface quality and the ability to coat
+thermal-sensitive materials such as those envisaged in spintronic devices.
+Pulsed Laser Deposition (PLD) is a technique that has the potential to meet the
+requirements stated above. In this work, we describe our efforts to grow
+chromium oxide thin films by PLD from Cr8O21 targets, using a KrF excimer
+laser. The as-deposited films were investigated by X-ray diffraction and
+Rutherford backscattering spectrometry. Structural and chemical composition
+studies showed that the films consist of a mixture of amorphous chromium oxides
+exhibiting different stoichiometries depending on the processing parameters,
+where nanocrystals of mainly Cr2O3 are dispersed. The analyses do not exclude
+the possibility of co-deposition of Cr2O3 and a low fraction of CrO2.
+  PACS: 81.15.Fg, 75.50.Dd",0605594v1
+2006-10-06,"Theoretical study of the insulating oxides and nitrides: SiO2, GeO2, Al2O3, Si3N4, and Ge3N4","An extensive theoretical study is performed for wide bandgap crystalline
+oxides and nitrides, namely, SiO_{2}, GeO_{2}, Al_{2}O_{3}, Si_{3}N_{4}, and
+Ge_{3}N_{4}. Their important polymorphs are considered which are for SiO_{2}:
+$\alpha$-quartz, $\alpha$- and $\beta$-cristobalite and stishovite, for
+GeO_{2}: $\alpha$-quartz, and rutile, for Al_{2}O_{3}: $\alpha$-phase, for
+Si_{3}N_{4} and Ge_{3}N_{4}: $\alpha$- and $\beta$-phases. This work
+constitutes a comprehensive account of both electronic structure and the
+elastic properties of these important insulating oxides and nitrides obtained
+with high accuracy based on density functional theory within the local density
+approximation. Two different norm-conserving \textit{ab initio}
+pseudopotentials have been tested which agree in all respects with the only
+exception arising for the elastic properties of rutile GeO_{2}. The agreement
+with experimental values, when available, are seen to be highly satisfactory.
+The uniformity and the well convergence of this approach enables an unbiased
+assessment of important physical parameters within each material and among
+different insulating oxide and nitrides. The computed static electric
+susceptibilities are observed to display a strong correlation with their mass
+densities. There is a marked discrepancy between the considered oxides and
+nitrides with the latter having sudden increase of density of states away from
+the respective band edges. This is expected to give rise to excessive carrier
+scattering which can practically preclude bulk impact ionization process in
+Si_{3}N_{4} and Ge_{3}N_{4}.",0610176v2
+2007-09-04,A first--order irreversible thermodynamic approach to a simple energy converter,"Several authors have shown that dissipative thermal cycle models based on
+Finite-Time Thermodynamics exhibit loop-shaped curves of power output versus
+efficiency, such as it occurs with actual dissipative thermal engines. Within
+the context of First-Order Irreversible Thermodynamics (FOIT), in this work we
+show that for an energy converter consisting of two coupled fluxes it is also
+possible to find loop-shaped curves of both power output and the so-called
+ecological function against efficiency. In a previous work Stucki [J.W. Stucki,
+Eur. J. Biochem. vol. 109, 269 (1980)] used a FOIT-approach to describe the
+modes of thermodynamic performance of oxidative phosphorylation involved in
+ATP-synthesis within mithochondrias. In that work the author did not use the
+mentioned loop-shaped curves and he proposed that oxidative phosphorylation
+operates in a steady state simultaneously at minimum entropy production and
+maximum efficiency, by means of a conductance matching condition between
+extreme states of zero and infinite conductances respectively. In the present
+work we show that all Stucki's results about the oxidative phosphorylation
+energetics can be obtained without the so-called conductance matching
+condition. On the other hand, we also show that the minimum entropy production
+state implies both null power output and efficiency and therefore this state is
+not fulfilled by the oxidative phosphorylation performance. Our results suggest
+that actual efficiency values of oxidative phosphorylation performance are
+better described by a mode of operation consisting in the simultaneous
+maximization of the so-called ecological function and the efficiency.",0709.0321v1
+2010-02-25,"Tuning the properties of complex transparent conducting oxides: role of crystal symmetry, chemical composition and carrier generation","The electronic properties of single- and multi-cation transparent conducting
+oxides (TCOs) are investigated using first-principles density functional
+approach. A detailed comparison of the electronic band structure of
+stoichiometric and oxygen deficient In$_2$O$_3$, $\alpha$- and
+$\beta$-Ga$_2$O$_3$, rock salt and wurtzite ZnO, and layered InGaZnO$_4$
+reveals the role of the following factors which govern the transport and
+optical properties of these TCO materials: (i) the crystal symmetry of the
+oxides, including both the oxygen coordination and the long-range structural
+anisotropy; (ii) the electronic configuration of the cation(s), specifically,
+the type of orbital(s) -- $s$, $p$ or $d$ -- which form the conduction band;
+and (iii) the strength of the hybridization between the cation's states and the
+p-states of the neighboring oxygen atoms. The results not only explain the
+experimentally observed trends in the electrical conductivity in the
+single-cation TCO, but also demonstrate that multicomponent oxides may offer a
+way to overcome the electron localization bottleneck which limits the charge
+transport in wide-bandgap main-group metal oxides. Further, the advantages of
+aliovalent substitutional doping -- an alternative route to generate carriers
+in a TCO host -- are outlined based on the electronic band structure
+calculations of Sn, Ga, Ti and Zr-doped InGaZnO$_4$. We show that the
+transition metal dopants offer a possibility to improve conductivity without
+compromising the optical transmittance.",1002.4827v1
+2010-06-18,Consistent Asymptotic Expansion of Mott's Solution for Oxide Growth,"Many relatively thick metal oxide films grow according to what is called the
+parabolic law L = 2At + . . . . Mott explained this for monovalent carriers by
+assuming that monovalent ions and electrons are the bulk charge carriers, and
+that their number fluxes vary as t^{-1/2} at sufficiently long t. In this
+theory no charge is present in the bulk, and surface charges were not
+discussed. However, it can be analyzed in terms of a discharging capacitor,
+with the oxide surfaces as the plates. The theory is inconsistent because the
+field decreases, corresponding to discharge, but there is no net current to
+cause discharge. The present work, which also includes non-monovalent carriers,
+systematically extends the theory and obtains the discharge current. Because
+the Planck-Nernst equations are nonlinear (although Gauss's Law and the
+continuity equations are linear) this leads to a systematic order-by-order
+expansion in powers of t^{-1/2} for the number currents, concentrations, and
+electric field during oxide growth. At higher order the bulk develops a
+non-zero charge density, with a corresponding non-uniform net current, and
+there are corrections to the electric field and the ion currents. The second
+order correction to ion current implies a logarithmic term in the thickness of
+the oxide layer: L = (2At)^{1/2} + B ln t + . . . . It would be of interest to
+verify this result with high-precision measurements.",1006.3819v1
+2010-06-25,Effect of doping of zinc oxide on the hole mobility of poly(3-hexylthiophene) in hybrid transistors,"Hybrid field effect transistors based on the organic polymer
+poly(3-hexylthiophene) (P3HT) and inorganic zinc oxide were investigated. In
+this report we present one of the first studies on hybrid transistors employing
+one polymeric transport layer. The sol-gel processed ZnO was modified via Al
+doping between 0.8 and 10 at.%, which allows a systematic variation of the zinc
+oxide properties, i.e. electron mobility and morphology. With increasing doping
+level we observe on the one hand a decrease of the electron mobilities by two
+orders of magnitude,on the other hand doping enforces a morphological change of
+the zinc oxide layer which enables the infiltration of P3HT into the inorganic
+matrix. X-ray reflectivity (XRR) measurements confirm this significant change
+in the interface morphology for the various doping levels. We demonstrate that
+doping of ZnO is a tool to adjust the charge transport in ZnO/P3HT hybrids,
+using one single injecting metal (Au bottom contact) on a SiO2 dielectric. We
+observe an influence of the zinc oxide layer on the hole mobility in P3HT which
+we can modify via Al doping of ZnO. Hence, maximum hole mobility of 5e-4
+cm^2/Vs in the hybrid system with 2 at.% Al doping. 5 at.% Al doping leads to a
+balanced mobility in the organic/inorganic hybrid system but also to a small
+on/off ratio due to high off-currents.",1006.4971v1
+2010-08-01,How and why electrostatic charge of combustible nanoparticles can radically change the mechanism and rate of their oxidation in humid atmosphere,"Electrostatically charged aerosol nanoparticles strongly attract surrounding
+polar gas molecules due to a charge-dipole interaction. In humid air, the
+substantial electrostatic attraction and acceleration of surrounding water
+vapour molecules towards charged combustible nanoparticles cause intense
+electrostatic hydration and preferential oxidation of these nanoparticles by
+accelerated water vapor molecules rather than non-polar oxygen molecules. In
+particular, electrostatic acceleration, acquired by surrounding water vapour
+molecules at a distance of their mean free path from the minimally charged iron
+metal nanoparticle can increase an oxidative activity of these polar molecules
+with respect to the nanoparticle by a factor of one million. Intense
+electrostatic hydration of charged metal nanoparticles converts the
+nanoparticle's oxide based shells into the hydroxide based electrolyte shells,
+transforming these nanoparticles into metal/air core-shell nanobatteries,
+periodically short-circuited by intra-particle field and thermionic electron
+emission. Partially synchronized breakdowns within trillions of
+nanoparticles-nanobatteries turn a cloud of charged nanoparticles-nanobatteries
+- ball lightning - into a powerful radio-frequency aerosol generator.
+Electrostatic hydration and charge-catalyzed oxidation of charged combustible
+nanoparticles also contribute to a self-oscillating thermocycling process of
+evolution and periodic auto-ignition of inflammable gases near to the
+nanoparticle's surface. The described effects might be of interest for the
+improvement of certain nanotechnological processes and to better understand
+ball lightning phenomenon.",1008.0162v1
+2011-02-13,Density functional theory based study of graphene and dielectric oxide interfaces,"We study the effects of insulating oxides in their crystalline forms on the
+energy band structure of monolayer and bilayer graphene using a \textit{first
+principles} density functional theory based electronic structure method and a
+local density approximation. We consider the dielectric oxides, SiO$_{2}$
+($\alpha$-quartz) and Al$_{2}$O$_{3}$ (alumina or $\alpha$-sapphire) each with
+two surface terminations. Our study suggests that atomic relaxations and
+resulting equilibrium separations play a critical role in perturbing the linear
+band structure of graphene in contrast to the less critical role played by
+dangling bonds that result from cleaving the crystal in a particular direction.
+We also see that with the addition of a second graphene layer, the Dirac cone
+is restored for the quartz surface terminations. Alumina needs more than two
+graphene layers to preserve the Dirac cone. Our results are at best
+semi-quantitative for the common amorphous forms of the oxides considered.
+However, crystalline oxides for which our results are quantitative provide an
+interesting option for graphene based electronics, particularly in light of
+recent experiments on graphene with crystalline dielectrics (hexagonal BN) that
+find considerable improvements in transport properties as compared to the those
+with amorphous dielectrics.",1102.2557v1
+2011-06-06,Evolution of an oxygen NEXAFS transition in the upper Hubbard band in α-Fe2O3 upon electrochemical oxidation,"Electrochemical oxidation of hematite ({\alpha}-Fe2O3) nano-particulate films
+at 600 mV vs. Ag+/AgCl reference in KOH electrolyte forms a species at the
+hematite surface which causes a new transition in the upper Hubbard band
+between the Fe(3d)-O(2p) state region and the Fe(4sp)-O(2p) region, as
+evidenced by oxygen near edge x-ray absorption fine structure (NEXAFS) spectra.
+The electrochemical origin of this transition suggests that it is related with
+a surface state. This transition, not known for pristine {\alpha}-Fe2O3 is at
+about the same x-ray energy, where pristine 1% Si doped Si:Fe2O3 has such
+transition. Occurrence of this state coincides with the onset of an oxidative
+dark current wave at around 535 mV - a potential range, where the tunneling
+exchange current has been previously reported to increase by three orders of
+magnitude with the valence band and the transfer coefficient by a factor of 10.
+Oxidation to only 200 mV does not form such extra NEXAFS feature, supporting
+that a critical electrochemical potential between 200 and 600 mV is necessary
+to change the electronic structure of the iron oxide at the surface. Decrease
+of the surface roughness, as suggested by visual inspection, profilometry and
+x-ray reflectivity, points to faceting as potential structural origin of the
+surface state.",1106.1089v1
+2013-01-08,Simulation of Metal/Oxide Interface Mobility: Effects of Mechanical Stresses on Geometrical Singularities,"During the last decade, an increasing importance has been given to the
+feedback of mechanical stresses on the chemical diffusion and, further, on
+corrosion. Many works point the active role of stresses on the material ageing
+especially on their negative consequences leading to the damaging of
+structures. Based on a theoretical study and using numerical tools and
+experimental results our previous works [1, on stress/diffusion coupling,
+highlight the strong influence of stress field on the diffusion process. The
+aim of the present paper is to describe the influence of some particular
+morphologies of the metal/oxide interface on both diffusion and oxidation
+process. The oxidation is assumed to be driven by a mass conservation law
+(Stefan's law) while the diffusion coefficient of oxygen in metal is locally
+influenced by the stress field. The stability of a waved-shape interface is
+studied in both cases: simple diffusion and coupled stress/diffusion process.
+In this purpose we have developed an original numerical model using a virtual
+metal/oxide interface of a mono-material with oxygen concentration-dependent
+parameters, which allows to operate easily with any shape of interface and to
+use simple finite element meshes. Furthermore, in order to underline in a more
+obvious way the consequences of mechanical stress on the diffusion process, a
+particular geometry is studied.",1301.1620v2
+2013-04-15,Salmonella chemoreceptors McpB and McpC mediate a repellent response to L-cystine: a potential mechanism to avoid oxidative conditions,"Chemoreceptors McpB and McpC in Salmonella enterica have been reported to
+promote chemotaxis in LB motility-plate assays. Of the chemicals tested as
+potential effectors of these receptors, the only response was towards
+L-cysteine and its oxidized form, L-cystine. Although enhanced radial migration
+in plates suggested positive chemotaxis to both amino acids, capillary assays
+failed to show an attractant response to either, in cells expressing only these
+two chemoreceptors. In vivo fluorescence resonance energy transfer (FRET)
+measurements of kinase activity revealed that in wild-type bacteria, cysteine
+and cystine are chemoeffectors of opposing sign, the reduced form being a
+chemoattractant and the oxidized form a repellent. The attractant response to
+cysteine was mediated primarily by Tsr, as reported earlier for E. coli. The
+repellent response to cystine was mediated by McpB / C. Adaptive recovery upon
+cystine exposure required the methyl-transferase/-esterase pair, CheR / CheB,
+but restoration of kinase activity was never complete (i.e. imperfect
+adaptation). We provide a plausible explanation for the attractant-like
+responses to both cystine and cysteine motility plates, and speculate that the
+opposing signs of response to this redox pair might afford Salmonella a
+mechanism to gauge and avoid oxidative environments.",1304.4006v1
+2014-11-07,An embryo of protocell membrane: The capsule of graphene oxide,"Many signs indicate that the graphene could widely occur on the early Earth.
+Here, we report a new theory that graphene might be an embryo of protocell
+membrane, and found several evidences. Firstly, the graphene oxide and
+phospholipid-graphene oxide composite would curl into capsules in strongly
+acidic saturated solution of Pb(NO3)2 at low temperature, providing a
+protective space for biochemical reactions. Secondly, L-animi acids exhibit
+higher reactivity than D-animi acids for graphene oxides in favor of the
+formation of left-handed proteins. Thirdly, monolayer graphene with nanopores
+prepared by unfocused 84Kr25+ has high selectivity for permeation of the
+monovalent metal ions (Rb+ > K+ > Cs+ > Na+ > Li+), but does not allow Cl-
+through, which could be attributed to the ion exchange of oxygen-containing
+groups on the rim of nanopores. It is similar to K+ channels, which would cause
+efflux of some ions from capsule of graphene oxides with the decrease of pH in
+the primitive ocean, creating a suitable inner condition for the origin of
+life. Consequently, the strongly acidic, high salinity and strong radiation as
+well as temperature changes in the early Earth, regarded as negative factors,
+would be indispensable for the origin of protocell. In short, graphene bred
+life, but digested gradually by the evolution.",1411.1903v2
+2014-12-25,Theoretical and experimental investigation of vacancy-based doping of monolayer MoS$_2$ on oxide,"Monolayer transition metal dichalcogenides are novel, gapped two-dimensional
+materials. Toward device applications, we consider MoS$_2$ layers on
+dielectrics, in particular in this work, the effect of vacancies on the
+electronic structure. In density-functional based simulations, we consider the
+effects of near-interface O vacancies in the oxide slab, and Mo or S vacancies
+in the MoS$_2$ layer. Band structures and atom-projected densities of states
+for each system and with differing oxide terminations were calculated, as well
+as those for the defect-free MoS$_2$-dielectrics system and for isolated
+dielectric layers for reference. Among our results, we find that with O
+vacancies, both the Hf-terminated HfO$_2$-MoS$_2$ system, and the O-terminated
+and H-passivated Al$_2$O$_3$-MoS$_2$ systems appear metallic due to doping of
+the oxide slab followed by electron transfer into the MoS$_2$, in manner
+analogous to modulation doping. The n-type doping of monolayer MoS$_2$ by
+high-k oxides with oxygen vacancies then is experimentally demonstrated by
+electrically and spectroscopically characterizing back-gated monolayer MoS$_2$
+field effect transistors encapsulated by oxygen deficient alumina and hafnia.",1412.7852v3
+2015-03-23,Implications of the band gap problem on oxidation and hydration in acceptor-doped barium zirconate,"Charge carrier concentrations in acceptor-doped proton-conducting perovskites
+are to a large extent determined by the hydration and oxidation of oxygen
+vacancies, which introduce protons and holes, respectively. First-principles
+modeling of these reactions involves calculation of formation energies of
+charged defects, which requires an accurate description of the band gap and the
+position of the band edges. Since density-functional theory (DFT) with local
+and semi-local exchange-correlation functionals (LDA and GGA) systematically
+fails to predict these quantities this can have serious implications on the
+modeling of defect reactions. In this study we investigate how the description
+of band gap and band edge positions affects the hydration and oxidation in
+acceptor-doped BaZrO$_3$. First-principles calculations are performed in
+combination with thermodynamic modeling in order to obtain equilibrium charge
+carrier concentrations at different temperatures and partial pressures. Three
+different methods have been considered: DFT with both semi-local (PBE) and
+hybrid (PBE0) exchange-correlation functionals, and many-body perturbation
+theory within the $G_0W_0$-approximation. All three methods yield similar
+results for the hydration reaction, which are consistent with experimental
+findings. For the oxidation reaction, on the other hand, there is a qualitative
+difference. PBE predicts the reaction to be exothermic while the two others
+predict an endothermic behavior. Results from thermodynamic modeling are
+compared with available experimental data, such as enthalpies, concentrations
+and conductivities, and only the results obtained with PBE0 and $G_0W_0$, with
+an endothermic oxidation behavior, give a satisfactory agreement with
+experiments.",1503.06612v1
+2015-07-06,Final-state effect on x-ray photoelectron spectrum of nominally $d^1$ and $n$-doped $d^0$ transition metal oxides,"We investigate the x-ray photoelectron spectroscopy (XPS) of nominally $d^1$
+and $n$-doped $d^0$ transition metal oxides including NbO$_2$, SrVO$_3$, and
+LaTiO$_3$ (nominally $d^1$), as well as $n$-doped SrTiO$_3$ (nominally $d^0$).
+In the case of single phase $d^1$ oxides, we find that the XPS spectra
+(specifically photoelectrons from Nb $3d$, V $2p$, Ti $2p$ core levels) all
+display at least two, and sometimes three distinct components, which can be
+consistently identified as $d^0$, $d^1$, and $d^2$ oxidation states (with
+decreasing order in binding energy). Electron doping increases the $d^2$
+component but decreases the $d^0$ component, whereas hole doping reverses this
+trend; a single $d^1$ peak is never observed, and the $d^0$ peak is always
+present even in phase-pure samples. In the case of $n$-doped SrTiO$_3$, the
+$d^1$ component appears as a weak shoulder with respect to the main $d^0$ peak.
+We argue that these multiple peaks should be understood as being due to the
+final-state effect and are intrinsic to the materials. Their presence does not
+necessarily imply the existence of spatially localized ions of different
+oxidation states nor of separate phases. A simple model is provided to
+illustrate this interpretation, and several experiments are discussed
+accordingly. The key parameter to determine the relative importance between the
+initial-state and final-state effects is also pointed out.",1507.01507v1
+2015-09-05,Two-Dimensional Oxide Topological Insulator With Iron-Pnictide Superconductor LiFeAs Structure,"By using first-principles calculations, we propose that ZrSiO can be looked
+as a three-dimensional (3D) oxide weak topological insulator (TI) and its
+single layer is a long-sought-after 2D oxide TI with a band gap up to 30 meV.
+Calculated phonon spectrum of the single layer ZrSiO indicates it is
+dynamically stable and the experimental achievements in growing oxides with
+atomic precision ensure that it can be readily synthesized. This will lead to
+novel devices based on TIs, the so called ""topotronic"" devices, operating under
+room-temperature and stable when exposed in the air. Thus, a new field of
+""topotronics"" will arise. Another intriguing thing is this oxide 2D TI has the
+similar crystal structure as the well-known iron-pnictide superconductor
+LiFeAs. This brings great promise in realizing the combination of
+superconductor and TI, paving the way to various extraordinary quantum
+phenomena, such as topological superconductor and Majorana modes. We further
+find that there are many other isostructural compounds hosting the similar
+electronic structure and forming a $WHM$-family with $W$ being Zr, Hf or La,
+$H$ being group IV or group V element, and $M$ being group VI one.",1509.01686v2
+2015-11-08,Stress Evolution in Lithium-ion Composite Electrodes during Electrochemical Cycling and Resulting Internal Pressures on the Cell Casing,"Composite cathode coatings made of a high energy density layered oxide
+(Li1.2Ni0.15Mn0.55Co0.1O2, theoretical capacity ~377 mAh/g), polyvinylidene
+fluoride (PVdF) binder, and electron-conduction additives, were bonded to an
+elastic substrate. An electrochemical cell, built by pairing the cathode with a
+capacity-matched graphite anode, was electrochemically cycled and the real-time
+average stress evolution in the cathode coating was measured using a
+substrate-curvature technique. Features in the stress evolution profile showed
+correlations with phase changes in the oxide, thus yielding data complementary
+to in situ XRD studies on this material. The stress evolution showed a complex
+variation with lithium concentration suggesting that the volume changes
+associated with phase transformations in the oxide are not monotonically
+varying functions of lithium concentration. The peak tensile stress in the
+cathode during oxide delithiation was approximately 1.5 MPa and the peak
+compressive stress during oxide lithiation was about 6 MPa. Stress evolution in
+the anode coating was also measured separately using the same technique. The
+measured stresses are used to estimate the internal pressures that develop in a
+cylindrical lithium-ion cell with jelly-roll electrodes.",1511.02445v1
+2016-04-26,Orbital reconstruction in nonpolar tetravalent transition-metal oxide layers,"A promising route to tailoring the electronic properties of quantum materials
+and devices rests on the idea of orbital engineering in multilayered oxide
+heterostructures. Here we show that the interplay of interlayer charge
+imbalance and ligand distortions provides a knob for tuning the sequence of
+electronic levels even in intrinsically stacked oxides. We resolve in this
+regard the $d$-level structure of layered Sr$_2$IrO$_4$ by electron spin
+resonance. While canonical ligand-field theory predicts $g_{\parallel}$-factors
+$\!<\!2$ for positive tetragonal distortions as present in Sr$_2$IrO$_4$, the
+experiment indicates $g_{\parallel}\!>\!2$. This implies that the iridium $d$
+levels are inverted with respect to their normal ordering. State-of-the-art
+electronic-structure calculations confirm the level switching in Sr$_2$IrO$_4$,
+whereas we find them in Ba$_2$IrO$_4$ to be instead normally ordered. Given the
+nonpolar character of the metal-oxygen layers, our findings highlight the
+tetravalent transition-metal 214 oxides as ideal platforms to explore
+$d$-orbital reconstruction in the context of oxide electronics.",1604.07780v1
+2016-10-11,2D surprises at the surface of 3D materials: confined electron systems in transition metal oxides,"The scope of this article is to review the state-of-the-art in the field of
+confined electron systems generated at the bare surfaces of transition metal
+oxides (TMOs). This scientific field is a prime example of a domain where
+two-dimensional physics and photoemission-based spectroscopic techniques have
+together set up the development of the story. The discovery of a high-mobility
+two-dimensional electron system (2DES) at interfaces of transition metal oxides
+has attracted an immense scientific interest due to new opportunities opened in
+the emerging field of oxide electronics. The subsequent paradigm shift from
+interfaces to the bare surfaces of TMOs made the confined electron system
+accessible to surface-sensitive spectroscopic techniques and this new era is
+the focus of the present article. We describe how results by means of
+Angle-Resolved Photoemission Spectroscopy (ARPES) establish the presence of
+confined electron carriers at the bare surface of SrTiO$_{3}$(100), which
+exhibit complex physics phenomena such as orbital ordering, electron-phonon
+interactions and spin splitting. The key element behind the 2DES generation is
+oxygen vacancies. Moreover, we review the experimental evidence on the
+generation of 2DESs on surfaces with different orientation, as well as on
+different TMO substrates. The electronic structure of the confined electron
+system responds to such changes, thereby providing external means for
+engineering its properties. Finally, we identify new directions for future
+research by introducing a device-friendly fabrication protocol for the
+generation of 2DESs on TMO surfaces.",1610.03221v1
+2017-02-01,Water Permeation through Layered Graphene-based Membranes: A Fully Atomistic Molecular Dynamics Investigation,"Graphene-based membranes have been investigated as promising candidates for
+water filtration and gas separation applications. Experimental evidences have
+shown that graphene oxide can be impermeable to liquids, vapors and gases,
+while allowing a fast permeation of water molecules. This phenomenon has been
+attributed to the formation of a network of nano capillaries that allow nearly
+frictionless water flow while blocking other molecules by steric hindrance
+effects. It is supposed that water molecules are transported through the
+percolated two-dimensional channels formed between graphene-based sheets.
+Although these channels allow fast water permeation in such materials, the flow
+rates are strongly dependent on how the membranes are fabricated. Also, some
+fundamental issues regarding the nanoscale mechanisms of water permeation are
+still not fully understood and their interpretation remains controversial. In
+this work, we have investigated the dynamics of water permeation through
+pristine graphene and graphene oxide model membranes. We have carried out fully
+atomistic classical molecular dynamics simulations of systems composed of
+multiple layered graphene-based sheets into contact with a water reservoir
+under controlled thermodynamics conditions (e. g., by varying temperature and
+pressure values). We have systematically analyzed how the transport dynamics of
+the confined nanofluids depend on the interlayer distances and the role of the
+oxide functional groups. Our results show the water flux is much more effective
+for graphene than for graphene oxide membranes. These results are attributed to
+the H-bonds formation between oxide functional groups and water, which traps
+the water molecules and precludes ultrafast water transport through the
+nanochannels.",1702.00250v1
+2017-03-16,Enhanced atomic layer etching of native aluminum oxide for ultraviolet optical applications,"We report on the development and application of an atomic layer etching (ALE)
+procedure based on alternating exposures of trimethylaluminum and anhydrous
+hydrogen fluoride (HF) implemented to controllably etch aluminum oxide. Our ALE
+process utilizes the same chemistry previously demonstrated in the atomic layer
+deposition of aluminum fluoride thin films, and can therefore be exploited to
+remove the surface oxide from metallic aluminum and replace it with thin
+fluoride layers in order to improve the performance of ultraviolet aluminum
+mirrors. This ALE process is modified relative to existing methods through the
+use of a chamber conditioning film of lithium fluoride, which is shown to
+enhance the loss of fluorine surface species and results in conformal
+layer-by-layer etching of aluminum oxide films. Etch properties were explored
+over a temperature range of 225 to 300 {\deg}C with the Al2O3 etch rate
+increasing from 0.8 to 1.2 {\AA} per ALE cycle at a fixed HF exposure of 60 ms
+per cycle. The effective etch rate has a dependence on the total HF exposure,
+but the process is shown to be scalable to large area substrates with a
+post-etch uniformity of better than 2% demonstrated on 125 mm diameter wafers.
+The efficacy of the ALE process in reducing interfacial native aluminum oxide
+on evaporated aluminum mirrors is demonstrated with characterization by x-ray
+photoelectron spectroscopy and measurements of ultraviolet reflectance at
+wavelengths down to 120 nm.",1703.05469v1
+2018-04-28,Ambient condition production of high quality reduced graphene oxide,"Reduced graphene oxide becomes one of the most popular materials for
+applications in various optical, electronic and sensor devices. Even though
+many methods have been already reported for reduced graphene oxide synthesis,
+they usually rise issues related to their efficiency, quality and environmental
+impact. This work demonstrates a simple, environmentally friendly and effective
+method for reducing graphene oxide under ambient conditions using nanosecond
+infrared laser irradiation. As a result, a Raman band intensity ratio of
+I(G)/I(D) of 4.59 was achieved with an average crystallite size of ~90 nm. This
+graphene is of higher quality than what can be achieved with most of the
+existing methods. Additionally, the demonstrated reduction technique allows the
+selective reduction of graphene oxide and control the amount of functional
+groups on the surface of the material. Gas sensors fabricated according to the
+proposed technique efficiently detect NO$_2$, NH$_3$, and H$_2$S with the
+sensitivity down to 10 ppm.",1804.10836v2
+2018-10-31,Modelling N2O dynamics of activated sludge biomass under nitrifying and denitrifying conditions: pathway contributions and uncertainty analysis,"Nitrous oxide (N2O) is a potent greenhouse gas emitted during biological
+wastewater treatment. A pseudo-mechanistic model describing three biological
+pathways for nitric oxide (NO) and N2O production was calibrated for mixed
+culture biomass from an activated sludge process using laboratory-scale
+experiments. The model (NDHA) comprehensively describes N2O producing pathways
+by both autotrophic ammonium oxidizing bacteria and heterotrophic bacteria.
+Extant respirometric assays and anaerobic batch experiments were designed to
+calibrate endogenous and exogenous processes (heterotrophic denitrification and
+autotrophic ammonium/nitrite oxidation) together with the associated net N2O
+production. Ten parameters describing heterotrophic processes and seven for
+autotrophic processes were accurately estimated (variance/mean < 25%). The
+model predicted NO and N2O dynamics at varying dissolved oxygen, ammonium and
+nitrite levels and was validated against an independent set of experiments with
+the same biomass. Aerobic ammonium oxidation experiments at two oxygen levels
+used for model evaluation (2 and 0.5 mg/L) indicated that both the nitrifier
+denitrification (42, 64%) and heterotrophic denitrification (7, 17%) pathways
+increased and dominated N2O production at high nitrite and low oxygen
+concentrations; while the nitrifier nitrification pathway showed the largest
+contribution at high dissolved oxygen levels (51, 19%). The uncertainty of the
+biological parameter estimates was propagated to N2O model outputs via Monte
+Carlo simulations as 95% confidence intervals. The accuracy of the estimated
+parameters resulted in a low uncertainty of the N2O emission factors (4.6 +-
+0.6% and 1.2 +- 0.1%).",1811.00004v1
+2019-05-20,Effect of UV radiation on the structure of graphene oxide in water and its impact on cytotoxicity and As(III) adsorption,"Graphene oxide (GO) is widely used in different applications, however once
+release into the environment it can change its structure and affect the
+transport of important contaminants such as arsenic. In this work we show that
+UV radiation, even in the range of 28-74 uW/cm2 of irradiance up to 120 h of
+exposure, can induce important changes in the structure of graphene oxide, by
+eliminating -OH and C=O functional groups. This reduction affected the
+stability of graphene oxide in water by decreasing its zeta potential from 41
+to 37 mV with the increase of the exposure time. Our results showed that after
+24 h of UV exposure, As(III) adsorption capacity decreased from 5 mg/g to 4.7
+mg/g, however after 48 h of irradiation the adsorption increased with time,
+reaching 5.1 mg/g at 120 h under 74 uW/cm2 of irradiation. Computer modelling
+showed that even a degraded GO structure can have an interaction energy of 53
+kcal/mol with H3AsO3. Furthermore, we observed that despite clear changes in
+surface composition and particle size, the reduction of graphene oxide
+maintained a high degree of cytotoxicity since cell viability decreased to 60%
+with a 50 ug/ml dose; except for the sample irradiated at 74 uW/cm2 for five
+days, which showed 20% with the same concentration.",1905.12167v1
+2010-05-20,Comparison of the Oxidation State of Fe in Comet 81P/Wild 2 and Chondritic-Porous Interplanetary Dust Particles,"The fragile structure of chondritic-porous interplanetary dust particles (CP-
+IDPs) and their minimal parent-body alteration have led researchers to believe
+these particles originate in comets rather than asteroids where aqueous and
+thermal alteration have occurred. The solar elemental abundances and
+atmospheric entry speed of CP-IDPs also suggest a cometary origin. With the
+return of the Stardust samples from Jupiter-family comet 81P/Wild 2, this
+hypothesis can be tested. We have measured the Fe oxidation state of 15 CP-IDPs
+and 194 Stardust fragments using a synchrotron-based x-ray microprobe. We
+analyzed ~300 nanograms of Wild 2 material - three orders of magnitude more
+material than other analyses comparing Wild 2 and CP-IDPs. The Fe oxidation
+state of these two samples of material are >2{\sigma} different: the CP-IDPs
+are more oxidized than the Wild 2 grains. We conclude that comet Wild 2
+contains material that formed at a lower oxygen fugacity than the parent body,
+or parent bodies, of CP-IDPs. If all Jupiter-family comets are similar, they do
+not appear to be consistent with the origin of CP-IDPs. However, comets that
+formed from a different mix of nebular material and are more oxidized than Wild
+2 could be the source of CP-IDPs.",1005.3858v1
+2016-11-21,The enabling electronic motif for topological insulation in ABO3 perovskites and its structural stability,"Stable oxide topological insulators (TIs) that could bring together the
+traditional oxide functionalities with the dissipationless surface states of
+TIs have been sought for years but none was found. Yet, heavier chalcogenides
+(selenides, tellurides) were readily found to be TIs. We clarify here the basic
+contradiction between TI-ness and stability which is maximal for oxides, and
+trace the basic design principles necessary to identify the window of
+opportunity of stable TIs. We first identify the electronic motif that can
+achieve topological band inversion (""topological gene"") in ABO3 as being a
+lone-pair electron-rich B atom (e.g. Te, I, Bi) at the octahedral site. We then
+illustrate that poorly screened oxide systems with large inversion energies can
+undergo energy-lowering atomic distortions that remove the band inversion. We
+identify the coexistence windows of TI functionality and structure stability
+for different pressures and find that the common cubic ABO3 structures have
+inversion energies lying outside this coexistence window at zero pressure but
+could be moved into the coexistence window at moderate pressures. Our study
+demonstrates the interplay between topological band inversion and structural
+stability and traces the basic principles needed to design stable oxide
+topological insulators at ambient pressures.",1611.06839v3
+2018-05-04,Silicon Oxide Electron-Emitting Nanodiodes,"Electrically driven on-chip electron sources that do not need to be heated
+have been long pursued because the current thermionic electron sources show the
+problems of high power consumption, slow temporal response, bulky size, etc.,
+but their realization remains challenging. Here we show that a nanogap formed
+by two electrodes on a silicon oxide substrate functions as an
+electron-emitting nanodiode after the silicon oxide in the nanogap is
+electrically switched to a high-resistance conducting state. A nanodiode based
+on graphene electrodes can be turned on by a voltage of ~7 V in ~100 ns and
+show an emission current of up to several microamperes, corresponding to an
+emission density of ~10^6 A cm^-2 and emission efficiency as high as 16.6%. We
+attribute the electron emission to be generated from a metal-insulator-metal
+tunneling diode on the substrate surface formed by the rupture of conducting
+filaments in silicon oxide. An array of 100 nanodiodes exhibits a global
+emission density of 5 A cm^-2 and stable emission with negligible current
+degradation over tens of hours under modest vacuum. The combined advantages of
+a low operating voltage, fast temporal response, high emission density and
+efficiency, convenient fabrication and integration, and stable emission in
+modest vacuum make silicon oxide electron-emitting nanodiodes a promising
+on-chip alternative to thermionic emission sources.",1805.01602v1
+2018-05-08,Evaluation of reduced-graphene-oxide-supported gold nanoparticles as catalytic system for electroreduction of oxygen in alkaline electrolyte,"Chemically-reduced graphene-oxide-supported gold nanoparticles are considered
+here as catalytic materials for the reduction of oxygen in alkaline medium.
+Gold nanoparticles are prepared by the chemical reduction method, in which the
+NaBH4-prereduced Keggin-type phosphomolybdate heteropolyblue acts as the
+reducing agent for the precursor (HAuCl4). Polyoxmetallate (PMo12O403-) capping
+ligands stabilize gold nanoparticle deposits, facilitate their dispersion and
+attachment to carbon supports. Indeed, it is apparent from the independent
+diagnostic voltammetric experiments (in 0.5 mol dm-3 H2SO4) that
+heteropolymolybdates form readily stable adsorbates on nanostructures of both
+gold and carbon (reduced graphene oxide and Vulcan). It is reasonable to expect
+that the polyoxometallate-assisted nucleation of gold has occurred in the
+proximity of oxygenated defects existing on carbon substrates. Under conditions
+of electrochemical diagnostic experiments (performed in 0.1 mol dm-3 KOH): (i)
+the phosphomolybdate adsorbates are removed from the interface as they undergo
+dissolution in alkaline medium; and (ii) the Au nanoparticles (Au loading, 30
+{\mu}g cm-2) remain well-dispersed on the carbon as evident from transmission
+electron microscopy. High electrocatalytic activity of the reduced-graphene
+oxide-supported Au nanoparticles toward reduction of oxygen in alkaline medium
+is demonstrated using cyclic and rotating ring-disk voltammetric experiments.
+Among important issues are possible activating interactions between gold and
+the support, as well as presence of structural defects existing on poorly
+organized graphitic structure of reduced graphene oxide (as evident from Raman
+spectroscopy).",1805.03156v1
+2011-11-29,Electronic properties of layered multicomponent wide-bandgap oxides: a combinatorial approach,"The structural, electronic, and optical properties of twelve multicomponent
+oxides with layered structure, RAMO$_4$, where R$^{3+}$=In or Sc; A$^{3+}$=Al
+or Ga; and M$^{2+}$=Ca, Cd, Mg, or Zn, are investigated using first-principles
+density functional approach. The compositional complexity of RAMO$_4$ leads to
+a wide range of band gap values varying from 2.45 eV for InGaCdO$_4$ to 6.29 eV
+for ScAlMgO$_4$. Strikingly, despite the different band gaps in the oxide
+constituents, namely, 2-4 eV in CdO, In$_2$O$_3$, or ZnO; 5-6 for Ga$_2$O$_3$
+or Sc$_2$O$_3$; and 7-9 eV in CaO, MgO, or Al$_2$O$_3$, the bottom of the
+conduction band in the multicomponent oxides is formed from the s-states of all
+cations and their neighboring oxygen p-states. We show that the hybrid nature
+of the conduction band in multicomponent oxides originates from the unusual
+five-fold atomic coordination of A$^{3+}$ and M$^{2+}$ cations which enables
+the interaction between the spatially-spread s-orbitals of adjacent cations via
+shared oxygen atoms. The effect of the local atomic coordination on the band
+gap, the electron effective mass, the orbital composition of the conduction
+band, and the expected (an)isotropic character of the electron transport in
+layered RAMO$_4$ is thoroughly discussed.",1111.6864v1
+2014-06-02,Superconductivity in titanium-based pnictide oxide compounds,"Superconductivity in a novel class of layered materials, Ti-based pnictide
+oxides, was recently discovered. These compounds have attracted interest since
+they combine features of copper oxide and iron pnictide superconductors. Here
+the transition metal (titanium) forms two-dimensional Ti$_2$O layers (anti
+structure to the CuO$_2$ planes), capped by pnictogen ions (similar to
+Fe$_2$As$_2$ layers). The pnictide oxide compounds show a spin or charge
+density wave phase which coexists with superconductivity in some members of the
+family. Unlike the cuprates, but similar to iron pnictides, the parent
+compounds of pnictide oxides are metals with specific nesting properties of the
+Fermi surface which leads to the density wave instability. The nature of the
+superconductivity, coexisting with the density wave order, and the possible
+competition or mutual interaction between both states is one of the central
+questions of recent studies. This short review summarizes the current knowledge
+from an experimental as well as theoretical point of view and discusses some of
+the open questions and possible future developments.",1406.0442v1
+2016-05-10,Two Dimensional Phosphorus Oxides as Energy and Information Materials,"Two-dimensional (2D) black phosphorus (i.e., phosphorene) has become a rising
+star in electronics. Recently, 2D phosphorus oxides with higher stability have
+been synthesized. In this work, we systematically explore the structures and
+properties of 2D phosphorus oxides on the basis of global optimization approach
+and first-principles calculations. We find that the structural features of 2D
+phosphorus oxides PxOy vary with the oxygen concentration. When the oxygen
+content is poor, the most stable 2D PxOy can be obtained by adsorbing O atoms
+on phosphorene. However, when the oxygen concentration becomes rich, stable
+structures are no longer based on phosphorene and will contain P-O-P motifs.
+For the 2D P4O4, we find that it has a direct band gap (about 2.24 eV), good
+optical absorption, and high stability in water, suggesting that it may be good
+candidate for photochemical water splitting application. Interestingly, 2D P2O3
+adopt two possible stable ferroelectric structures (P2O3-I and P2O3-II) as the
+lowest energy configurations within a given layer thickness. The electric
+polarizations of P2O3-I and P2O3-II are perpendicular and parallel to the
+lateral plane, respectively. We propose that 2D P2O3 could be used in a novel
+nanoscale multiple-state memory device. Our work suggests that 2D phosphorus
+oxides may be excellent functional materials.",1605.02830v1
+2017-10-24,Strong localization of oxidized Co3+ state in cobalt-hexacyanoferrate,"Secondary batteries are important energy storage devices for a mobile
+equipment, an electric car, and a large-scale energy storage. Nevertheless,
+variation of the local electronic state of the battery materials in the charge
+(or oxidization) process are still unclear. Here, we investigated the local
+electronic state of cobalt-hexacyanoferrate (Na$_x$Co[Fe(CN)$_6$]$_{0.9}$), by
+means of resonant inelastic X-ray scattering (RIXS) with high energy resolution
+(~100 meV). The L-edge RIXS is one of the most powerful spectroscopic technique
+with element- and valence-selectivity. We found that the local electronic state
+around Co$^{2+}$ in the partially-charged
+Na$_{1.1}$Co$^{2+}$$_{0.5}$Co$^{3+}$$_{0.5}$[Fe$^{2+}$(CN)$_6$]$_{0.9}$ film (x
+= 1.1) is the same as that of the discharged
+Na$_{1.6}$Co$^{2+}$[Fe$^{2+}$(CN)$_6$]$_{0.9}$ film (x = 1.6) within the energy
+resolution, indicating that the local electronic state around Co$^{2+}$ is
+invariant against the partial oxidization. In addition, the local electronic
+state around the oxidized Co$^{3+}$ is essentially the same as that of the
+fully-charged film
+Co$^{3+}$[Fe$^{2+}$(CN)$_6$]$_{0.3}$[Fe$^{3+}$(CN)$_6$]$_{0.6}$ (x = 0.0) film.
+Such a strong localization of the oxidized Co$^{3+}$ state is advantageous for
+the reversibility of the redox process, since the localization reduces extra
+reaction within the materials and resultant deterioration.",1710.08657v1
+2017-10-26,Microwave Irradiation Assisted Deposition of Ga2O3 on III-nitrides for deep-UV opto-electronics,"We report on the deposition of gallium oxide using microwave irradiation
+technique on III nitride epi layers. We also report on the first demonstration
+of a gallium oxide device, a visible blind deep UV detector, with GaN based
+heterostructure as the substrate. The film deposited in the solution medium, at
+less than 200 C, using a metalorganic precursor, was nanocrystalline. XRD
+confirms that as deposited film when annealed at high temperature turns
+polycrystalline beta gallium oxide. SEM shows the as deposited film to be
+uniform, with a surface roughness of 4 to 5 nm, as revealed by AFM.
+Interdigitated metal semiconductor metal MSM devices with Ni,Au contact
+exhibited peak spectral response at 230 nm and a good visible rejection ratio.
+This first demonstration of a deep-UV detector on beta-gallium oxide on III
+nitride stack is expected to open up new possibilities of functional and
+physical integration of beta gallium oxide and GaN material families towards
+enabling next generation high performance devices by exciting band and
+heterostructure engineering.",1710.09615v3
+2017-12-22,The Role of Oxygen in Ionic Liquid Gating on 2D Cr2Ge2Te6: a Non-Oxide Material,"Ionic liquid gating can markedly modulate the materials' carrier density so
+as to induce metallization, superconductivity, and quantum phase transitions.
+One of the main issues is whether the mechanism of ionic liquid gating is an
+electrostatic field effect or an electrochemical effect, especially for oxide
+materials. Recent observation of the suppression of the ionic liquid
+gate-induced metallization in the presence of oxygen for oxide materials
+suggests the electrochemical effect. However, in more general scenarios, the
+role of oxygen in ionic liquid gating effect is still unclear. Here, we perform
+the ionic liquid gating experiments on a non-oxide material: two-dimensional
+ferromagnetic Cr2Ge2Te6. Our results demonstrate that despite the large
+increase of the gate leakage current in the presence of oxygen, the oxygen does
+not affect the ionic liquid gating effect (< 5 % difference), which suggests
+the electrostatic field effect as the mechanism on non-oxide materials.
+Moreover, our results show that the ionic liquid gating is more effective on
+the modulation of the channel resistances compared to the back gating across
+the 300 nm thick SiO2.",1712.08281v1
+2018-09-03,Atomic and electronic structure of graphene oxide/Cu interface,"The results of X-ray photoemission (XPS) and valence bands spectroscopy,
+optically stimulated electron emission (OSEE) measurements and density
+functional theory based modeling of graphene oxide (GO) placed on Cu via an
+electrophoretic deposition (EPD) are reported. The comparison of XPS spectra of
+EPD prepared GO/Cu composites with those of as prepared GO, strongly reduced
+GO, pure and oxidized copper demonstrate the partial (until C/O ratio about
+two) removal of oxygen-containing functional groups from GO simultaneously with
+the formation of copper oxide-like layers over the metallic substrate. OSEE
+measurements evidence the presence of copper oxide phase in the systems
+simultaneously with the absence of contributions from GO with corresponding
+energy gap. All measurements demonstrate the similarity of the results for
+different thickness of GO cover of the copper surface. Theoretical modeling
+demonstrates favorability of migration of oxygen-containing functional groups
+from GO to the copper substrate only for the case of C/O ratio below two and
+formation of Cu-O-C bonds between substrate and GO simultaneously with the
+vanishing of the energy gap in GO layer. Basing on results of experimental
+measurements and theoretical calculations we suggest the model of atomic
+structure for Cu/GO interface as Cu/CuO/GO with C/O ratio in gapless GO about
+two.",1809.00450v1
+2019-07-30,Energy Conversion via Metal Nanolayers,"Current approaches for electric power generation from nanoscale conducting or
+semi-conducting layers in contact with moving aqueous droplets are promising as
+they show efficiencies of around 30 percent, yet, even the most successful ones
+pose challenges regarding fabrication and scaling. Here, we report stable,
+all-inorganic single-element structures synthesized in a single step that
+generate electrical current when alternating salinity gradients flow along its
+surface in a liquid flow cell. 10 nm to 30 nm thin nanolayers of iron,
+vanadium, or nickel produce several tens of mV and several microA cm^-2 at
+aqueous flow velocities of just a few cm s^-1. The principle of operation is
+strongly sensitive to charge-carrier motion in the thermal oxide nano-overlayer
+that forms spontaneously in air and then self terminates. Indeed, experiments
+suggest a role for intra-oxide electron transfer for Fe, V, and Ni nanolayers,
+as their thermal oxides contain several metal oxidation states, whereas
+controls using Al or Cr nanolayers, which self-terminate with oxides that are
+redox inactive under the experimental conditions, exhibit dramatically
+diminished performance. The nanolayers are shown to generate electrical current
+in various modes of application with moving liquids, including sliding liquid
+droplets, salinity gradients in a flowing liquid, and in the oscillatory motion
+of a liquid without a salinity gradient.",1907.13170v1
+2020-04-21,Role of interfacial oxidation in generation of spin-orbit torques,"We report that current-induced spin-orbit torques (SOTs) in
+heavy-metal/ferromagnetic-metal bilayers are strongly altered by the oxidation
+of the ferromagnetic layer near the interface. We measured damping-like (DL)
+and field-like (FL) SOTs for Pt/Co and Pt/Ni$_{81}$Fe$_{19}$ (Pt/Py) films
+using spin-torque ferromagnetic resonance. In the Pt/Co film, we found that the
+oxidation of the Co layer near the interface enhances both DL and FL SOTs in
+spite of the insulating nature of the CoO$_x$ layer. The enhancement of the
+SOTs disappears by inserting a thin Ti layer at the Pt/CoO$_x$ interface,
+indicating that the dominant source of the SOTs in the Pt/CoO$_x$/Co film is
+the spin-orbit coupling at the Pt/CoO$_x$ interface. In contrast to the
+Pt/CoO$_x$/Co film, the SOTs in the Pt/PyO$_x$/Py film are dominated by the
+bulk spin-orbit coupling. Our result shows that the interfacial oxidation of
+the Pt/Py film suppresses the DL-SOT and reverses the sign of the FL-SOT. The
+change of the SOTs can be attributed to the change of the real and imaginary
+parts of the spin mixing conductance induced by the insertion of the insulating
+PyO$_x$ layer. These results show that the interfacial oxidation provides an
+effective way to manipulate the strength and sign of the SOTs.",2004.09837v1
+2020-12-05,Origin of ferroelectricity and multiferroicity in binary oxide thin films,"The observation of ferroelectric, ferromagnetic and ferroelastic phases in
+thin films of binary oxides attract the broad interest of scientists and
+engineers. However, the theoretical consideration of observed behaviour
+physical nature was performed mainly for HfO2 thin films from the first
+principles, and in the framework of Landau-Ginzburg-Devonshire (LGD)
+phenomenological approach with a special attention to the role of oxygen
+vacancies in both cases. Allowing for generality of the LGD theory we applied
+it to the group of binary oxides in this work. The calculations have been
+performed in the assumption that oxygen vacancies, as elastic dipoles, can be
+partially transformed into electric dipoles due to the defect site-induced
+and/or surface-induced inversion symmetry breaking (via e.g. piezoelectric
+effect), and can ""migrate"" entire the depth of an ultra-thin film. We
+calculated the dependence of the film polarization on the applied voltage for
+room temperature and different film thickness. Since the many films of binary
+oxide are ferroelectric and ferromagnetic due to the same oxygen vacancies,
+they can be multiferroics. Performed calculations have shown that thin films of
+binary oxides can be considered as a new wide class of multiferroics with broad
+spectra of physical properties useful for application in nanoelectronics and
+nanotechnology. The properties can be controlled by the choice of oxygen
+vacancies concentration, film thickness and special technological treatment,
+such as annealing.",2012.03136v1
+2017-05-13,Effects of layer thickness on the mechanical behavior of oxidation-strengthened Zr/Nb nanoscale multilayers,"The mechanical behaviour and deformation mechanisms of magnetron-sputtered
+Zr/Nb nanoscale multilayers were analysed as a function of the periodicity (L =
+10 and 75 nm) and annealing time at 350C (2-336 hrs). The strength of the
+as-deposited multilayers was independent of the layer thickness and it was
+controlled by the co-deformation of the Zr and Nb layers. Annealing led to
+transformation of the Zr layers into ZrO2 after a few hours, while the Nb
+layers oxidised at a much slower rate. The volumetric expansion associated with
+the oxidation led to the formation of cracks at the interfaces and within the
+ZrO2 layers for the multilayers with L = 75 nm but not in the case of L = 10
+nm. The nanoindentation hardness increased significantly after annealing due to
+the contribution of the residual stresses associated with the volume increase
+due to oxidation and to the higher strength of the oxides. The strength
+increase after annealing, as measured by micropillar compression tests, was
+smaller than that measured by nanoindentation, as it did not include the
+contribution of the residual stresses, which were relieved during micropillar
+fabrication. The nanolaminate with L = 10 nm presented the highest strength and
+toughness as damage during oxidation was suppressed, and a deformation
+mechanism controlled by the formation of shear bands.",1705.04805v2
+2017-11-13,Electronic Reconstruction Enhanced Tunneling Conductance at Terrace Edges of Ultrathin Oxide Films,"Quantum mechanical tunneling of electrons across ultrathin insulating oxide
+barriers has been studied extensively for decades due to its great potential in
+electronic device applications. In the few-nanometer-thick epitaxial oxide
+films, atomic-scale structural imperfections, such as the ubiquitously existed
+one-unit-cell-high terrace edges, can dramatically affect the tunneling
+probability and device performance. However, the underlying physics has not
+been investigated adequately. Here, taking ultrathin BaTiO3 films as a model
+system, we report an intrinsic tunneling conductance enhancement near the
+terrace edges. Scanning probe microscopy results demonstrate the existence of
+highly-conductive regions (tens of nanometers-wide) near the terrace edges.
+First-principles calculations suggest that the terrace edge geometry can
+trigger an electronic reconstruction, which reduces the effective tunneling
+barrier width locally. Furthermore, such tunneling conductance enhancement can
+be discovered in other transition-metal-oxides and controlled by surface
+termination engineering. The controllable electronic reconstruction could
+facilitate the implementation of oxide electronic devices and discovery of
+exotic low-dimensional quantum phases.",1711.04622v1
+2018-06-06,Epitaxial Strain-Dependence of Band Gaps in Oxynitrides compared to Oxides,"Perovskite oxynitrides are a promising class of material for photocatalytic
+water-splitting due to their small band gaps and suitably aligned band edges.
+Recently, epitaxially strained oxynitrides started to attract interest due to
+the possibility to engineer the anion order and ferroelectric distortions.
+However, contrary to oxides there have been no studies on the band-gap
+evolution in oxynitrides with epitaxial strain. Here, we investigate, using
+density functional theory calculations, the influence of epitaxial strain on
+the band gap of two different oxynitrides and compare our results with oxides.
+As opposed to cubic oxides, where both compressive and tensile strain narrow
+the band-gap, we find that the anion order leads to non-degenerate N
+\textit{2p} bands already at zero strain, which leads to opposite and anion
+order-dependent evolutions of the band gap under compressive and tensile
+strain. Further, we find that in oxynitrides polar distortions increase the
+band gap by up to 1 eV for 4% strain whereas for oxides the increase is only
+about 0.1 eV for the same amount of strain. The reason for this difference is
+the larger ionic radius of nitrogen leading to larger ferroelectric distortions
+and a stronger dependence of the band gap on the distortions amplitude. These
+results imply that ferroelectric distortions are strongly detrimental to light
+absorption and that their suppression, for example above a critical
+temperature, should result in a marked decrease in band gap and enhanced
+absorption of visible light.",1806.02050v1
+2019-02-18,Giant Conductivity Modulation of Aluminum Oxide using Focused Ion Beam,"Precise control of the conductivity of semiconductors through doping has
+enabled the creation of advanced electronic devices, similarly, the ability to
+control the conductivity in oxides can enable novel advanced electronic and
+optoelectronic functionalities. While this was successfully shown for
+moderately insulating oxides, such as In2O3, a reliable method for increasing
+the conductivity of highly insulating, wide bandgap dielectrics, such as
+aluminum oxide (Al2O3), has not been reported yet. Al2O3 is a material of
+significant technological interest, permeating diverse fields of application,
+thanks to its exceptional mechanical strength and dielectric properties. Here
+we present a versatile method for precisely changing the conductivity of Al2O3
+. Our approach greatly exceeds the magnitude of the best previously reported
+change of conductivity in an oxide. Our method uses focused ion beam to produce
+conductive zones with nanoscale resolution within the insulating Al2O3 matrix.
+We investigated the source of conductivity modulation and identified
+trap-assisted conduction in the ion damage-induced defects as the main charge
+transport mechanism. Temperature-dependency of the conductivity and optical
+characterization of the patterned areas offer further insight into the nature
+of the conduction mechanism. We also show that the process is extremely
+reproducible and robust against moderate annealing temperatures and chemical
+environment. The record conductivity modulation, combined with the nanoscale
+patterning precision allows the creation of conductive zones within a highly
+insulating, mechanically hard, chemically inert, and bio-compatible matrix,
+which could find broad applications in electronics, optoelectronics, and
+medical implants",1902.06821v1
+2019-03-05,Selecting between two transition states by which water oxidation intermediates on an oxide surface decay,"While catalytic mechanisms on electrode surfaces have been proposed for
+decades, the pathways by which the product's chemical bonds evolve from the
+initial charge-trapping intermediates have not been resolved in time. Here, we
+discover a reactive population of charge-trapping intermediates with states in
+the middle of a semiconductor's band-gap to reveal the dynamics of two parallel
+transition state pathways for their decay. Upon photo-triggering the water
+oxidation reaction from the n-SrTiO3 surface with band-gap, pulsed excitation,
+the intermediates' microsecond decay reflects transition state theory (TST)
+through: (1) two distinct and reaction dependent (pH, T, Ionic Strength, and
+H/D exchange) time constants, (2) a primary kinetic salt effect on each
+activation barrier and an H/D kinetic isotope effect on one, and (3) realistic
+activation barrier heights (0.4 - 0.5 eV) and TST pre-factors (10^11 - 10^12
+Hz). A photoluminescence from midgap states in n-SrTiO3 reveals the reaction
+dependent decay; the same spectrum was previously assigned by us to
+hole-trapping at parallel Ti-O(dot)-Ti (bridge) and perpendicular Ti-O(dot)
+(oxyl) O-sites using in situ ultrafast vibrational and optical spectroscopy.
+Therefore, the two transition states are naturally associated with the decay of
+these respective intermediates. Furthermore, we show that reaction conditions
+select between the two pathways, one of which reflects a labile intermediate
+facing the electrolyte (the oxyl) and the other a lattice oxygen (the bridge).
+Altogether, we experimentally isolate an important activation barrier for water
+oxidation, which is necessary for designing water oxidation catalysts with high
+O2 turn over. Moreover, in isolating it, we identify competing mechanisms for
+O2 evolution at surfaces and show how to use reaction conditions to select
+between them.",1903.01675v1
+2019-03-07,Low-loss waveguides on Y-cut thin film lithium niobate: towards acousto-optic applications,"We investigate the dependence of photonic waveguide propagation loss on the
+thickness of the buried oxide layer in Y-cut lithium niobate on insulator
+substrate to identify trade-offs between optical losses and electromechanical
+coupling of surface acoustic wave (SAW) devices for acousto-optic applications.
+Simulations show that a thicker oxide layer reduces the waveguide loss but
+lowers the electromechanical coupling coefficient of the SAW device. Optical
+racetrack resonators with different lengths were fabricated by argon plasma
+etching to experimentally extract waveguide losses. By increasing the thickness
+of the oxide layer from 1 {\mu}m to 2 {\mu}m, propagation loss of 2 {\mu}m (1
+{\mu}m) wide waveguide was reduced from 1.85 dB/cm (3 dB/cm) to as low as 0.37
+dB/cm (0.77 dB/cm), and, resonators with quality factor greater than 1 million
+were demonstrated. An oxide thickness of approximately 1.5 {\mu}m is sufficient
+to significantly reduce propagation loss due to leakage into the substrate and
+simultaneously attain good electromechanical coupling in acoustic devices. This
+work not only provides insights on the design and realization of low-loss
+photonic waveguides in lithium niobate, but most importantly offers
+experimental evidence on how the oxide thickness directly impacts losses and
+guides its selection for the synthesis of high-performance acousto-optic
+devices in Y-cut lithium niobate on insulator.",1903.07567v1
+2019-03-27,Ferroelectric ZrO$_{2}$ monolayers as buffer layers between SrTiO$_{3}$ and Si,"A monolayer of ZrO$_{2}$ has recently been grown on the Si(001) surface and
+shown to have ferroelectric properties, which signifies the realization of the
+lowest possible thickness in ferroelectric oxides [M. Dogan et al., Nano Lett.,
+18 (1) (2018)]. In our previous computational study, we reported on the
+multiple (meta)stable configurations of ZrO$_{2}$ monolayers on Si, and how
+switching between a pair of differently polarized configurations may explain
+the observed ferroelectric behavior of these films [M. Dogan and S.
+Ismail-Beigi, arXiv:1902.01022 (2019)]. In the current study, we conduct a
+DFT-based investigation of (i) the effect of oxygen content on the ionic
+polarization of the oxide, and (ii) the role of zirconia monolayers as buffer
+layers between silicon and a thicker oxide film that is normally paraelectric
+on silicon, e.g. SrTiO$_{3}$. We find that (i) total energy-vs-polarization
+behavior of the monolayers, as well as interface chemistry, is highly dependent
+on the oxygen content; and (ii) SrTiO$_{3}$/ZrO$_{2}$/Si stacks exhibit
+multiple (meta)stable configurations and polarization profiles, i.e. zirconia
+monolayers can induce ferroelectricity in oxides such as SrTiO$_{3}$ when used
+as a buffer layer. This may enable a robust non-volatile device architecture
+where the thickness of the gate oxide (here strontium titanate) can be chosen
+according to the desired properties.",1903.11716v1
+2019-11-11,Strain-driven superplasticity and modulation of electronic properties of ultrathin tin (II) oxide: A first-principles study,"2D-layered tin (II) oxide (SnO) has recently emerged as a promising bipolar
+channel material for thin-film transistors and complementary
+metal-oxide-semiconductor devices. In this work, we present a first-principles
+investigation of the mechanical properties of ultrathin SnO, as well as the
+electronic implications of tensile strain ($\epsilon$) under both uniaxial and
+biaxial conditions. Bulk-to-monolayer transition is found to significantly
+lower the Young's and shear moduli of SnO, highlighting the importance of
+interlayer Sn-Sn bonds in preserving structural integrity. Unprecedentedly,
+few-layer SnO exhibits superplasticity under uniaxial deformation conditions,
+with a critical strain to failure of up to 74% in the monolayer. Such
+superplastic behavior is ascribed to the formation of a tri-coordinated
+intermediate (referred to here as h-SnO) beyond $\epsilon$ = 14%, which
+resembles a partially-recovered orthorhombic phase with relatively large work
+function and wide indirect band gap. The broad structural range of tin (II)
+oxide under strongly anisotropic mechanical loading suggests intriguing
+possibilities for realizing novel hybrid nanostructures of SnO through strain
+engineering. The findings reported in this study reveal fundamental insights
+into the mechanical behavior and strain-driven electronic properties of tin
+(II) oxide, opening up exciting avenues for the development of SnO-based
+nanoelectronic devices with new, non-conventional functionalities.",1911.04039v1
+2019-10-21,Experimental Investigation of the Settling Characteristics of Carbon and Metal Oxide Nanofuels,"Fuels dispersed with engineered nanoparticle additives, or nanofuels, are
+desirable for the vastly different combustion properties such as combustion
+rate and ignition delay they exhibit compared to base fuels. The stability of
+such nanofuels over time and under different particle loadings is a very
+important parameter to consider before they can be put into practical use. Many
+techniques exist today to analyze suspension stability, which have been
+developed to analyze water-based nanofluids. Sometimes these techniques can be
+expensive, and/or require specialized equipment, and/or require a method that
+is invasive and disturbs the suspension. Present research uses a non-contact,
+non-invasive, low-cost experimental setup to analyze suspension stability over
+long periods of time. Nanofuels made from carbon-based nanomaterials (acetylene
+black, multiwalled carbon nanotubes) and metal oxide nanomaterials (copper
+oxide, aluminum oxide) with hydrocarbon fuels (canola biodiesel, petrodiesel)
+have been prepared and their settling rates have been analyzed over the period
+of three days. It is found that metal oxides go through several metastable
+states as they settle. The effect of initial concentration and liquid column
+height is shown. It is hoped that present research showcases the positive
+traits of the presented technique and will spark further interest in nanofuel
+stability.",1911.12238v1
+2020-08-22,High-Performance Thermoelectric Oxides Based on Spinel Structure,"High-performance thermoelectric oxides could offer a great energy solution
+for integrated and embedded applications in sensing and electronics industries.
+Oxides, however, often suffer from low Seebeck coefficient when compared with
+other classes of thermoelectric materials. In search of high-performance
+thermoelectric oxides, we present a comprehensive density functional
+investigation, based on GGA$+U$ formalism, surveying the 3d and 4d
+transition-metal-containing ferrites of the spinel structure. Consequently, we
+predict MnFe$_2$O$_4$ and RhFe$_2$O$_4$ have Seebeck coefficients of $\sim \pm
+600$ $\mu$V K$^{-1}$ at near room temperature, achieved by light hole and
+electron doping. Furthermore, CrFe$_2$O$_4$ and MoFe$_2$O$_4$ have even higher
+ambient Seebeck coefficients at $\sim \pm 700$ $\mu$V K$^{-1}$. In the latter
+compounds, the Seebeck coefficient is approximately a flat function of
+temperature up to $\sim 700$ K, offering a tremendous operational convenience.
+Additionally, MoFe$_2$O$_4$ doped with $10^{19}$ holes/cm$^3$ has a calculated
+thermoelectric power factor of $689.81$ $\mu$W K$^{-2}$ m$^{-1}$ at $300$ K,
+and $455.67$ $\mu$W K$^{-2}$ m$^{-1}$ at $600$ K. The thermoelectric properties
+predicted here can bring these thermoelectric oxides to applications at lower
+temperatures traditionally fulfilled by more toxic and otherwise burdensome
+materials.",2008.09759v1
+2020-10-29,Disassembling of TEMPO-oxidized cellulose fibers: intersheet and interchain interactions in the isolation of nanofibers and unitary chains,"Cellulose disassembly is an important issue in designing nanostructures using
+cellulose-based materials. In this work, we present a joint of experimental and
+theoretical study addressing the disassembly of cellulose nanofibrils. Through
+2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) mediated oxidation processes,
+combined with atomic force microscopy results, we find the formation of
+nanofibers with diameters corresponding to a single cellulose polymer chain.
+The formation of these polymer chains is ruled by repulsive electrostatic
+interactions between the oxidized chains. Further first-principles calculations
+have been done in order to provide an atomistic understanding the cellulose
+disassembling processes, focusing on the balance of the interchain and
+intersheet interactions upon oxidation. Firstly we analyse these interaction in
+pristine systems, where we found the intersheet interaction stronger than the
+interchain one. In the oxidized systems, we have considered the formation of
+(charged) carboxylate groups along the inner sites of elementary fibrils. We
+show a net charge concentration on the carboxylate groups, supporting the
+emergence of repulsive electrostatic interactions between the cellulose
+nanofibers. Indeed, our total energy results show that the weakening of the
+binding strength between the fibrils is proportional to the concentration and
+the net charge density of the carboxylate group. Moreover, by comparing
+interchain and intersheet binding energies, we found that most of the
+disassembly processes should take place by breaking the interchain
+O--H$\cdots$O hydrogen bond interactions, and thus supporting the experimental
+observation of single and double cellulose polymeric chains.",2010.15686v2
+2020-11-17,Covalent Grafting of Polyoxometalate Hybrids onto Flat Silicon/Silicon Oxide: Insights from POMs Layers on Oxides,"Immobilization of polyoxometalates (POMs) onto oxides is relevant to many
+applications in the fields of catalysis, energy conversion/storage or molecular
+electronics. Optimization and understanding the molecule/oxide interface is
+crucial to rationally improve the performance of the final molecular materials.
+We herein describe the synthesis and covalent grafting of POM hybrids with
+remote carboxylic acid functions onto flat Si/SiO2 substrates. Special
+attention has been paid to the characterization of the molecular layer and to
+the description of the POM anchoring mode at the oxide interface through the
+use of various characterization techniques, including ellipsometry, AFM, XPS
+and FTIR. Finally, electron transport properties were probed in a vertical
+junction configuration and energy level diagrams have been drawn and discussed
+in relation with the POM molecular electronic features inferred from
+cyclic-voltammetry, UV-visible absorption spectra and theoretical calculations.
+The electronic properties of these POM-based molecular junctions are driven by
+the POM LUMO (d-orbitals) whatever the nature of the tether or the anchoring
+group.",2011.08953v1
+2021-04-07,Antioxidant activity and toxicity study of cerium oxide nanoparticles stabilized with innovative functional copolymers,"Oxidative stress, which is one of the main harmful mechanisms of pathologies
+including is-chemic stroke, contributes to both neurons and endothelial cell
+damages, leading to vascular lesions. Although many antioxidants have been
+tested in preclinical studies, no treatment is currently available for stroke
+patients. Since cerium oxide nanoparticles (CNPs) exhibit remarkable
+antioxidant capacities, our objective is to develop an innovative coating to
+enhance CNPs biocompatibility without disrupting their antioxidant capacities
+or enhance their toxicity. This study reports the synthesis and
+characterization of functional polymers and their impact on the enzyme-like
+catalytic activity of CNPs. To study the toxicity and the antioxidant
+properties of CNPs for stroke and particularly endothelial damages, in vitro
+studies are conducted on a cerebral endothelial cell line (bEnd.3). Despite
+their internalization in bEnd.3 cells, coated CNPs are devoid of cytotoxicity.
+Microscopy studies report an intracellular localization of CNPs, more precisely
+in endosomes. All CNPs reduces glutamate-induced intracellular production of
+ROS in endothelial cells but one CNP significantly reduces both the production
+of mitochondrial super-oxide anion and DNA oxidation. In vivo studies report a
+lack of toxicity in mice. This study there-fore describes and identifies
+biocompatible CNPs with interesting antioxidant properties for ischemic stroke
+and related pathologies.",2104.03005v1
+2021-05-21,Deciphering the Rotational Spectrum of the First Excited Torsional State of Propylene Oxide,"The first excited torsional state of the chiral molecule propylene oxide,
+$\mathrm{CH_{3}C_{2}H_{3}O}$, is investigated from millimeter up to
+sub-millimeter wavelengths (75-950 GHz). The first excited vibrational mode of
+propylene oxide, $\upsilon_{24}$, is analysed using the programs ERHAM and
+XIAM. Rotational constants and tunneling parameters are provided, and a
+description of the A-E splittings due to internal rotation is given.
+Furthermore, the potential barrier height to internal rotation $V_{3}$ is
+determined to be $V_{3} = 894.5079(259) \mathrm{cm^{-1}}$ . Our results are
+compared with quantum chemical calculations and literature values. We present a
+line list of the dense spectrum of the first excited torsional state of
+propylene oxide in the (sub-)millimeter range. Our results will be useful for
+further studies of chiral molecules in vibrationally excited states, and will
+enable astronomers to search for rotational transitions originating from
+$\upsilon_{24}$ of propylene oxide in interstellar space.",2105.10248v1
+2021-07-01,Solid Source Metal-Organic Molecular Beam Epitaxy of Epitaxial RuO2,"A seemingly simple oxide with a rutile structure, RuO2 has been shown to
+possess several intriguing properties ranging from strain-stabilized
+superconductivity to a strong catalytic activity. Much interest has arisen
+surrounding the controlled synthesis of RuO2 films but, unfortunately,
+utilizing atomically-controlled deposition techniques like molecular beam
+epitaxy (MBE) has been difficult due to the ultra-low vapor pressure and low
+oxidation potential of Ru. Here, we demonstrate the growth of epitaxial,
+single-crystalline RuO2 films on different substrate orientations using the
+novel solid-source metal-organic (MO) MBE. This approach circumvents these
+issues by supplying Ru using a pre-oxidized solid metal-organic precursor
+containing Ru. High-quality epitaxial RuO2 films with bulk-like
+room-temperature resistivity of 55 micro-ohm-cm were obtained at a substrate
+temperature as low as 300 C. By combining X-ray diffraction, transmission
+electron microscopy, and electrical measurements, we discuss the effect of
+substrate temperature, orientation, film thickness, and strain on the structure
+and electrical properties of these films. Our results illustrating the use of
+novel solid-source MOMBE approach paves the way to the atomic-layer controlled
+synthesis of complex oxides of stubborn metals, which are not only difficult to
+evaporate but also hard to oxidize.",2107.00193v1
+2021-07-06,Reactivity of Ru oxides with air radiolysis products investigated by theoretical calculations,"Quantitative predictions of the release of volatile radiocontaminants of
+ruthenium (Ru) in the environment from either nuclear power plants (NPP) or
+fuel recycling accidents present significant uncertainties while estimated by
+severe accidents nuclear analysis codes. Observations of Ru from either
+experimental or modeling works suggest that the main limitations relate to the
+poor evaluation of the kinetics of gaseous Ru in the form of RuO$_3$ and
+RuO$_4$. This work presents relativistic correlated quantum chemical
+calculations performed to determine the possible reactions pathways leading to
+the formation of gaseous Ru oxides under NPP severe accident conditions, as a
+result of reactions of RuO$_2$ gaseous with air radiolysis products, namely
+nitrous and nitrogen oxides. The geometries of the relevant species were
+optimized with the TPSSh-5%HF functional of the density, while the total
+electronic energies were computed at the CCSD(T) level with extrapolations to
+the complete basis set CBS limit. The reaction pathways were fully
+characterized by localizing the transition states and all intermediate
+structures using the internal coordinate reaction algorithm (IRC). The rate
+constants were determined over the temperature range 250-2500 K. It is revealed
+that the less kinetically limiting pathway to form Ru gaseous fraction is the
+oxidation of Ru by nitrogen oxide, corroborating experimental observations.",2107.02631v2
+2021-08-04,Quasi-HfO$_x$/ AlO$_y$ and AlO$_y$/ HfO$_x$ Based Memristor Devices: Role of Bi-layered Oxides in Digital Set and Analog Reset Switching,"Understanding the resistive switching behavior, or the resistance change, of
+oxide-based memristor devices, is critical to predicting their responses with
+known electrical inputs. Also, with the known electrical response of a
+memristor, one can confirm its usefulness in non-volatile memory and/or in
+artificial neural networks. Although bi- or multi-layered oxides have been
+reported to improve the switching performance, compared to the single oxide
+layer, the detailed explanation about why the switching can easily be improved
+for some oxides combinations is still missing. Herein, we fabricated two types
+of bi-layered heterostructure devices, quasi-HfO$_x$/AlO$_y$ and
+AlO$_y$/HfO$_x$ sandwiched between Au electrodes, and their electrical
+responses are investigated. For a deeper understanding of the switching
+mechanism, the performance of a HfOx only device is also considered, which
+serves as a control device. The role of bi-layered heterostructures is
+investigated using both the experimental and simulated results. Our results
+suggest that synergistic switching performance can be achieved with a proper
+combination of these materials and/or devices. These results open the avenue
+for designing more efficient double- or multi-layers memristor devices for an
+analog response.",2108.02247v2
+2021-08-16,Physics-based Constitutive Modeling of Photo-oxidative Aging in Semi-Crystalline Polymers based on Chemical Characterization Techniques,"This paper proposes a physio-chemically-based constitutive framework to
+simulate and predict the response of semi-crystalline low-density polyethylene
+(LDPE) to severe photo-oxidation. Photo-oxidation induced by exposure to
+Ultra-Violet (UV) light and oxygen is the dominant degradation mechanism
+affecting the lifespan of LDPE. In this work, we propose evolution functions
+for the material properties in the constitutive equations of
+\cite{boyce2000constitutive} to incorporate the effects of photo-oxidation on
+the mechanical response of LDPE. The evolution functions are based on
+chemically verified processes that are responsible for material degradation,
+namely the change in crystallinity and mass loss relative to the initial
+pristine films over exposure time. Changes in crystallinity and mass loss are
+characterized by Differential Scanning Calorimetry (DSC) and Quartz Crystal
+Microbalance with Dissipation Monitoring (QCM-D) experiments, respectively.
+Connecting the physio-chemical processes affecting polymer network evolution to
+the mechanical response of LDPE bypasses the need for defining fitting
+parameters that carry no physical meaning. The developed constitutive framework
+is validated with respect to a series of in-house uniaxial tensile tests
+performed on LDPE aged for different UV exposure times. Comparison of the
+constitutive framework versus experimental mechanical tests also confirms the
+accuracy of DSC and QCM-D as rigorous techniques to monitor and characterize
+degradation in LDPE films. The outcome shed light on the evolution of the
+macromolecular network in LDPE under extreme photo-oxidation and the evolution
+of the associated mechanical material properties.",2108.07143v1
+2021-10-12,Topological Defects and Unique Stacking Disorders in Honeycomb Layered Oxide $\rm K_2Ni_2TeO_6$ Nanomaterials: Implications for Rechargeable Batteries,"Endowed with a multitude of exquisite properties such as rich
+electrochemistry, superb topology and eccentric electromagnetic phenomena,
+honeycomb layered oxides have risen to the top echelons of science with
+applications in diverse fields ranging from condensed matter physics,
+solid-state chemistry, materials science, solid-state ionics to
+electrochemistry. However, these oxides are vastly underutilised as their
+underlying atomistic mechanisms remain unexplored. Therefore, in this study,
+atomic-resolution imaging on pristine $\rm K_2Ni_2TeO_6$ along multiple zone
+axes was conducted using spherical aberration-corrected scanning transmission
+electron microscopy (Cs-corrected STEM) to reveal hitherto unreported nanoscale
+topological defects and curvature which can be associated with various phase
+transitions. Furthermore, we discover the coexistence of a stacking variant
+with P3-type sequence alongside the well-reported P2-type stacking sequence in
+such honeycomb layered oxides. Our findings have the potential to inspire
+further experimental and theoretical studies into the role of stacking and
+topology in the functionality of honeycomb layered oxides, for instance, as
+high-performance electrode materials for rechargeable batteries.",2110.09233v1
+2021-12-16,Collisional excitation and non-LTE modelling of interstellar chiral propylene oxide,"The first set of theoretical cross sections for propylene oxide (CH3CHCH2O)
+colliding with cold He atoms has been obtained at the full quantum level using
+a high-accuracy potential energy surface. By scaling the collision reduced
+mass, rotational rate coefficients for collisions with para-H2 are deduced in
+the temperature range 5-30 K. These collisional coefficients are combined with
+radiative data in a non-LTE radiative transfer model in order to reproduce
+observations of propylene oxide made towards the Sagittarius B2(N) molecular
+cloud with the Green Bank and Parkes radio telescopes. The three detected
+absorption lines are found to probe the cold (~ 10 K) and translucent (nH ~
+2000 cm-3) gas in the outer edges of the extended Sgr B2(N) envelope. The
+derived column density for propylene oxide is Ntot ~ 3e12 cm-2, corresponding
+to a fractional abundance relative to total hydrogen of ~ 2.5e-11. The present
+results are expected to help our understanding of the chemistry of propylene
+oxide, including a potential enantiomeric excess, in the cold interstellar
+medium.",2112.08924v2
+2022-01-31,Performance Analysis of Novel Propellant Oxidizers using Molecular Modelling and Nozzle Flow Simulations,"The primary target of this paper is to present novel compounds in view of
+their possible use as oxidizers in propulsion applications using molecular
+modeling calculations and supersonic flow simulations. Carbon-based
+heterocyclic compounds tend to have strained molecular structures leading to
+high heats of formation and energetic behavior. In the present work, molecular
+modeling calculations for molecules of 37 such potential propellant oxidizers
+are presented. Density functional theory (B3LYP) was employed for the geometry
+optimization of the proposed molecular structures using the 6-311++G(d,p) basis
+set. Heats of formation of the compounds were calculated using the molecular
+modeling results. Appropriate propellant compositions were considered with the
+proposed compounds as oxidizer components and Ideal specific impulse
+(Ivac,ideal*) was calculated for each composition assuming isentropic flow,
+computed using the NASA CEA software package. To predict the actual delivered
+specific impulse (Ivac,act*), supersonic nozzle flow simulations of equilibrium
+product gases of each propellant composition have been carried out using
+OpenFOAM. The standard k-epsilon turbulence model for compressible flows
+including rapid distortion theory (RDT) based compression term, has been
+employed. As the problem is inherently transient in nature, local time stepping
+(LTS) methodology has been further implemented to reach a steady-state
+solution. These simulations accounted for divergence losses, turbulence losses
+and boundary layer losses and gave a more realistic estimation of the specific
+impulse. It was observed that the Ivac,act* for all propellant compositions lie
+between 88% to 91% of the corresponding ideal value. The newly proposed
+oxidizers showed considerable improvement in propulsion performance as compared
+to ammonium perchlorate.",2202.00107v2
+2022-02-09,Scalable $\rm Al_2O_3-TiO_2$ Conductive Oxide Interfaces as Defect Reservoirs for Resistive Switching Devices,"Resistive switching devices herald a transformative technology for memory and
+computation, offering considerable advantages in performance and energy
+efficiency. Here we employ a simple and scalable material system of conductive
+oxide interfaces and leverage their unique properties for a new type of
+resistive switching device. For the first time, we demonstrate an $\rm
+Al_2O_3-TiO_2$ based valence-change resistive switching device, where the
+conductive oxide interface serves both as the back electrode and as a reservoir
+of defects for switching. The amorphous-polycrystalline $\rm Al_2O_3-TiO_2$
+conductive interface is obtained following the technological path of
+simplifying the fabrication of the two-dimensional electron gases (2DEGs),
+making them more scalable for practical mass integration. We combine physical
+analysis of the device chemistry and microstructure with comprehensive
+electrical analysis of its switching behavior and performance. We pinpoint the
+origin of the resistive switching to the conductive oxide interface, which
+serves as the bottom electrode and as a reservoir of oxygen vacancies. The
+latter plays a key role in valence-change resistive switching devices. The new
+device, based on scalable and complementary metal-oxide-semiconductor (CMOS)
+technology-compatible fabrication processes, opens new design spaces towards
+increased tunability and simplification of the device selection challenge.",2202.04477v2
+2022-06-18,Free-Standing Epitaxial SrTiO$_3$ Nanomembranes via Remote Epitaxy using Hybrid Molecular Beam Epitaxy,"The epitaxial growth of functional materials using a substrate with a
+graphene layer is a highly desirable method for improving structural quality
+and obtaining free-standing epitaxial nano-membranes for scientific study,
+applications, and economical reuse of substrates. However, the aggressive
+oxidizing conditions typically employed to grow epitaxial perovskite oxides can
+damage graphene. Here, we demonstrate a technique based on hybrid molecular
+beam epitaxy that does not require an independent oxygen source to achieve
+epitaxial growth of complex oxides without damaging the underlying graphene.
+The technique produces films with self-regulating cation stoichiometry control
+and epitaxial orientation to the oxide substrate. Furthermore, the films can be
+exfoliated and transferred to foreign substrates while leaving the graphene on
+the original substrate. These results open the door to future studies of
+previously unattainable free-standing nano-membranes grown in an
+adsorption-controlled manner by hybrid molecular beam epitaxy, and has
+potentially important implications for the commercial application of perovskite
+oxides in flexible electronics.",2206.09094v1
+2022-08-02,Highly Efficient and Selective Extraction of Gold by Reduced Graphene Oxide,"Materials that are capable of extracting gold from complex sources,
+especially electronic waste (e-waste) with high efficiency are needed for gold
+resource sustainability and effective e-waste recycling. However, it remains
+challenging to achieve high extraction capacity to trace amount of gold, and
+precise selectivity to gold over a wide range of complex co-existing elements.
+Here we report a reduced graphene oxide (rGO) material that has an ultrahigh
+extraction capacity for trace amounts of gold (1,850 mg/g and 1,180 mg/g to 10
+ppm and 1 ppm gold). The excellent gold extraction behavior is accounted to the
+graphene areas and oxidized regions of rGO. The graphene areas spontaneously
+reduce gold ions to metallic gold, and the oxidized regions provide a good
+dispersibility so that efficient adsorption and reduction of gold ions by the
+graphene area can be realized. The rGO is also highly selective to gold ions.
+By controlling the protonation process of the functional groups on the oxidized
+regions of rGO, it shows an exclusive gold extraction without adsorption of 14
+co-existing elements seen in e-waste. These discoveries are further exploited
+in highly efficient, continuous gold recycling from e-waste with good
+scalability and economic viability, as exemplified by extracting gold from
+e-waste using a rGO membrane based flow-through process.",2208.01435v1
+2022-08-03,"Reactive Laser Synthesis of Ultra-high-temperature Ceramics HfC, ZrC, TiC, HfN, ZrN, and TiN for Additive Manufacturing","Ultra-high-temperature ceramics (UHTCs) are optimal structural materials for
+applications that require extreme temperature resilience, resistance to
+chemically aggressive environments, wear, and mechanical stress. Processing
+UHTCs with laser-based additive manufacturing (AM) has not been fully realized
+due to a variety of obstacles. In this work, selective laser reaction sintering
+(SLRS) techniques were investigated for the production of near net-shape UHTC
+ceramics such as HfC, ZrC, TiC, HfN, ZrN, and TiN. Group IV transition metal
+and metal oxide precursor materials were chemically converted and
+reaction-bonded into layers of UHTCs using single-step selective laser
+processing in CH4 or NH3 gas that might be compatible with prevailing powder
+bed fusion techniques. Conversion of either metals (Hf, Zr and Ti) or metal
+oxides (HfO2, ZrO2, and TiO2) particles was first investigated to examine
+reaction mechanisms and volume changes associated with SLRS of single-component
+precursor systems. SLRS processing of metal or metal oxide alone produced near
+stoichiometric UHTC phases with yields up to 100 wt% total for carbides and
+nitrides. However, for single component precursors, gas-solid reactivity
+induced volumetric changes resulted in residual stresses and cracking in the
+product layer. To mitigate conversion-induced stresses, composite metal/metal
+oxide precursors were employed to compensate for the volume changes of either
+the metal (which expands during conversion) or the metal oxide precursor (which
+contracts).",2208.02041v2
+2022-09-02,Oxygen dissociation on the C3N monolayer: A first-principles study,"The oxygen dissociation and the oxidized structure on the pristine C3N
+monolayer in exposure to air are the inevitably critical issues for the C3N
+engineering and surface functionalization yet have not been revealed in detail.
+Using the first-principles calculations, we have systematically investigated
+the possible O2 adsorption sites, various O2 dissociation pathways and the
+oxidized structures. It is demonstrated that the pristine C3N monolayer shows
+more O2 physisorption sites and exhibits stronger O2 adsorption than the
+pristine graphene. Among various dissociation pathways, the most preferable one
+is a two-step process involving an intermediate state with the chemisorbed O2
+and the barrier is lower than that on the pristine graphene, indicating that
+the pristine C3N monolayer is more susceptible to oxidation than the pristine
+graphene. Furthermore, we found that the most stable oxidized structure is not
+produced by the most preferable dissociation pathway but generated from a
+direct dissociation process. These results can be generalized into a wide range
+of temperatures and pressures using ab initio atomistic thermodynamics. Our
+findings deepen the understanding of the chemical stability of 2D crystalline
+carbon nitrides under ambient conditions, and could provide insights into the
+tailoring of the surface chemical structures via doping and oxidation.",2209.01193v4
+2022-11-08,Gallium-doped Zinc Oxide: Nonlinear Reflection and Transmission Measurements and Modeling in the ENZ Region,"Strong nonlinear materials have been sought after for decades for
+applications in telecommunications, sensing, and quantum optics. Gallium-doped
+zinc oxide is a II-VI transparent conducting oxide that shows promising
+nonlinearities similar to indium tin oxide and aluminum-doped zinc oxide for
+the telecommunications band. Here we explore its nonlinearities in the epsilon
+near zero (ENZ) region and show n2,eff values on the order of 4.5x10-3 cm2GW-1
+for IR pumping on 200-300 nm thin films. Measuring nonlinear changes in
+transmission and reflection with a white light source probe in the near-IR
+while exciting in the near-IR provides data in both time and wavelength. Three
+films varying in thickness, optical loss, and ENZ crossover wavelength are
+numerically modeled and compared to experimental data showing agreement for
+both dispersion and temporal relaxation. In addition, we discuss optimal
+excitation and probing wavelengths occur around ENZ for thick films but are
+red-shifted for thin films where our model provides an additional degree of
+freedom to explore. Obtaining accurate nonlinear measurements is a difficult
+and time-consuming task where our method in this paper provides experimental
+and modeled data to the community for an ENZ material of interest.",2211.04306v2
+2023-03-22,Open-tunneled oxides as intercalation host for multivalent ion (Ca and Al) batteries: A DFT study,"Lithium-ion batteries (LIBs) are ubiquitous in everyday applications.
+However, Lithium (Li) is a limited resource on the planet and is therefore not
+sustainable. As an alternative to lithium, earth-abundant and cheaper
+multivalent metals such as aluminum (Al) and calcium (Ca) have been actively
+researched in battery systems. However, finding suitable intercalation hosts
+for multivalent-ion batteries is urgently needed. Open-tunneled oxides are a
+particular category of microparticles distinguished by the presence of
+integrated one-dimensional channels or nanopores. This work focuses on two
+promising open-tunnel oxides, viz: Niobium Tungsten Oxide (NTO) and Molybdenum
+Vanadium Oxide (MoVO). We find that the MoVO structure can adsorb greater
+numbers of multivalent ions than NTO due to its larger surface area and
+different shapes. The MoVO structure can adsorb Ca, Li, and Al ions with
+adsorption potential at around 4 to 5 eV. However, the adsorption potential for
+hexagonal channels of Al ion drops to 1.73 eV because of less channel area. NTO
+structure has an insertion/adsorption potential of 4.4 eV, 3.4 eV, and 0.9 eV
+for one Li, Ca, and Al, respectively. In general, Ca ion is more adsorbable
+than Al ion in both MoVO and NTO structures. Bader charge analysis and charge
+density plot reveals the role of charge transfer and ion size on the insertion
+of multivalent ions such as Ca and Al into MoVO and NTO systems. Our results
+provide general guidelines to explore other multivalent ions for battery
+applications.",2303.12301v1
+2023-03-27,Understanding the chemical coupling between ground-level ozone and oxides of nitrogen in ambient air at industrial and commercial sites in central India,"This study investigates the hourly concentrations of Ground-level Ozone (O3),
+Nitric Oxide (NO), Nitrogen Dioxide (NO2), and Oxides of Nitrogen (NOx) in
+ambient air, along with the various meteorological parameters viz., ambient
+temperature, relative humidity, wind speed, and solar radiation over one year,
+from August 2020 to July 2021 for an industrial and commercial site in Madhya
+Pradesh, a central state in India. We also analyze the chemical coupling
+between the O3 and ambient NO, NO2, and NOx at both sites during the daytime.
+We focus on understanding how the concentration of the oxidant OX (a
+combination of ozone and nitrogen dioxide) changes in relation to levels of NOx
+(a combination of nitrogen oxides) to determine whether the atmospheric sources
+of OX are dependent on the NOx-independent or regional contributions and
+NOx-dependent or local contributions. We also observe a significant positive
+correlation of O3 with ambient temperature and solar radiation but a strong
+negative correlation with relative humidity for the considered period. We found
+the monthly variations of the pollutants' concentrations show a strong
+seasonality dependence. O3 concentration becomes highest/lowest during
+summer/monsoon for both sites. In contrast, NOx exhibits the maximum and
+minimum concentration during monsoon and summer for both sites. The daily
+variation shows the opposite trend for O3 and NOx. O3 reaches a peak at mid-day
+around 14: 00 Hrs when ambient temperature also goes to maximum and has the
+minimum value at night time due to lack of sunlight.",2303.15238v1
+2023-04-21,Conversion of La$_2$Ti$_2$O$_7$ to LaTiO$_2$N via Ammonolysis: An ab-initio Investigation,"Perovskite oxynitrides are, due to their reduced band gap compared to oxides,
+promising materials for photocatalytic applications. They are most commonly
+synthesized from {110} layered Carpy-Galy (A$_2$B$_2$O$_7$}) perovskites via
+thermal ammonolysis, i.e. the exposure to a flow of ammonia at elevated
+temperature. The conversion of the layered oxide to the non-layered oxynitride
+must involve a complex combination of nitrogen incorporation, oxygen removal
+and ultimately structural transition by elimination of the interlayer shear
+plane. Despite the process being commonly used, little is known about the
+microscopic mechanisms and hence factors that could ease the conversion. Here
+we aim to derive such insights via density functional theory calculations of
+the defect chemistry of the oxide and the oxynitride as well as the oxide's
+surface chemistry. Our results point to the crucial role of surface oxygen
+vacancies in forming clusters of NH$_3$ decomposition products and in
+incorporating N, most favorably substitutionally at the anion site. N then
+spontaneously diffuses away from the surface, more easily parallel to the
+surface and in interlayer regions, while diffusion perpendicular to the
+interlayer plane is somewhat slower. Once incorporation and diffusion lead to a
+local N concentration of about 70% of the stoichiometric oxynitride
+composition, the nitridated oxide spontaneously transforms to a
+nitrogen-deficient oxynitride.",2304.10999v2
+2023-05-07,Photocatalytic oxidation in few-layer Tellurene for loss-invariant integrated photonic resonance trimming,"Two-dimensional materials with unique physicochemical properties promote
+photocatalytic activities. As the 2D material composites research studies the
+statistical average of complex catalytic behaviors, an integrated photonic
+platform allows clean and single flake level photo-catalytic investigations
+with precisely quantified photocatalytic activities. In this paper, we track
+fluence-dependent photo-oxidation in two-dimensional Tellurene (2D Te) by the
+evanescently coupled micro-resonator. Nearly 32 perent of oxidation is achieved
+in 10 nm 2D Te flake, compared to only 4.5% oxidation in 30 nm sample, probed
+by the resonance shift in silicon microring resonators (MRRs) substrate. The
+wider bandgap in the few layers of 2D Te allows faster charge transfer to
+adsorbed oxygen for a more efficient photocatalytic redox reaction. The
+photo-oxidation in hybrid 2D Te results in an invariant lineshapes of optical
+transmission resonance for wavelength trimming (more than 3 times resonance
+bandwidth). The low threshold power, near-infrared, and in-waveguide resonance
+trimming scheme is compatible with most integrated photonic setups for easy
+fixing the nanofabrication-induced random resonance deviation for integrated
+photonic circuit applications in wavelength-division-multiplexing systems and
+spin qubits quantum computing.",2305.04342v1
+2023-05-12,Two-dimensional layered materials meet perovskite oxides: A combination for high-performance electronic devices,"As the Si-based transistors scale down to atomic dimensions, the basic
+principle of current electronics, which heavily relies on the tunable charge
+degree of freedom, faces increasing challenges to meet the future requirements
+of speed, switching energy, heat dissipation, packing density as well as
+functionalities. Heterogeneous integration, where dissimilar layers of
+materials and functionalities are unrestrictedly stacked at an atomic scale, is
+appealing to next-generation electronics, such as multi-functional,
+neuromorphic, spintronic and ultra-low power devices, because it unlocks
+technologically useful interfaces of distinct functionalities. Recently, the
+combination of functional perovskite oxides and the two-dimensional layered
+materials (2DLMs) led to unexpected functionalities and enhanced device
+performance. In this review, we review the recent progress of the heterogeneous
+integration of perovskite oxides and 2DLMs from the perspectives of fabrication
+and interfacial properties, electronic applications, challenges as well as
+outlooks. In particular, we focus on three types of attractive applications,
+namely field-effect transistors, memory, and neuromorphic electronics. The van
+der Waals integration approach is extendible to other oxides and 2DLMs, leading
+to almost unlimited combinations of oxides and 2DLMs and contributing to future
+high-performance electronic and spintronic devices.",2305.15418v1
+2023-05-26,Topotactic Transition: A Promising Opportunity for Creating New Oxides,"Topotactic transition is a structural phase change in a matrix crystal
+lattice mediated by the ordered loss/gain and rearrangement of atoms, leading
+to unusual coordination environments and metal atoms with rare valent states.
+As early as in 1990s, low temperature hydride reduction was utilized to realize
+the topotactic transition. Since then, topological transformations have been
+developed via multiple approaches. Especially, the recent discovery of the
+Ni-based superconductivity in infinite-layer nickelates has greatly boosted the
+topotactic transition mean to synthesizing new oxides for exploring exotic
+functional properties. In this review, we have provided a detailed and
+generalized introduction to oxygen-related topotactic transition. The main body
+of our review include four parts: the structure-facilitated effects, the
+mechanism of the topotactic transition, some examples of topotactic transition
+methods adopted in different metal oxides (V, Mn, Fe, Co, Ni) and the related
+applications. This work is to provide timely and thorough strategies to
+successfully realize topotactic transitions for researchers who are eager to
+create new oxide phases or new oxide materials with desired functions.",2305.16605v1
+2023-11-19,Fast and Facile Synthesis Route to Epitaxial Oxide Membrane Using a Sacrificial Layer,"The advancement in thin-film exfoliation for synthesizing oxide membranes has
+opened up new possibilities for creating artificially-assembled
+heterostructures with structurally and chemically incompatible materials. The
+sacrificial layer method is a promising approach to exfoliate as-grown films
+from a compatible material system, allowing their integration with dissimilar
+materials. Nonetheless, the conventional sacrificial layers often possess
+intricate stoichiometry, thereby constraining their practicality and
+adaptability, particularly when considering techniques like Molecular Beam
+Epitaxy (MBE). This is where easy-to-grow binary alkaline earth metal oxides
+with a rock salt crystal structure are useful. These oxides, which include (Mg,
+Ca, Sr, Ba)O, can be used as a sacrificial layer covering a much broader range
+of lattice parameters compared to conventional sacrificial layers and are
+easily dissolvable in deionized water. In this study, we show the epitaxial
+growth of single-crystalline perovskite SrTiO3 (STO) on sacrificial layers
+consisting of crystalline SrO, BaO, and Ba1-xCaxO films, employing a hybrid MBE
+method. Our results highlight the rapid (< 5 minutes) dissolution of the
+sacrificial layer when immersed in deionized water, facilitating the
+fabrication of millimeter-sized STO membranes. Using high-resolution x-ray
+diffraction, atomic-force microscopy, scanning transmission electron
+microscopy, impedance spectroscopy, and scattering-type near-field optical
+microscopy (SNOM), we demonstrate epitaxial STO membranes with bulk-like
+intrinsic dielectric properties. The employment of alkaline earth metal oxides
+as sacrificial layers is likely to simplify membrane synthesis, particularly
+with MBE, thus expanding research possibilities.",2311.11448v1
+2010-11-11,Nonlinear Insulator in Complex Oxides,"The insulating state is one of the most basic electronic phases in condensed
+matter. This state is characterised by an energy gap for electronic excitations
+that makes an insulator electrically inert at low energy. However, for complex
+oxides, the very concept of an insulator must be re-examined. Complex oxides
+behave differently from conventional insulators such as SiO2, on which the
+entire semiconductor industry is based, because of the presence of multiple
+defect levels within their band gap. As the semiconductor industry is moving to
+such oxides for high-dielectric (high-k) materials, we need to truly understand
+the insulating properties of these oxides under various electric field
+excitations. Here we report a new class of material called nonlinear insulators
+that exhibits a reversible electric-field-induced metal-insulator transition.
+We demonstrate this behaviour for an insulating LaAlO3 thin film in a
+metal/LaAlO3/Nb-SrTiO3 heterostructure. Reproducible transitions were observed
+between a low-resistance metallic state and a high-resistance non-metallic
+state when applying suitable voltages. Our experimental results exclude the
+possibility that diffusion of the metal electrodes or oxygen vacancies into the
+LaAlO3 layer is occurring. Instead, the phenomenon is attributed to the
+formation of a quasi-conduction band (QCB) in the defect states of LaAlO3 that
+forms a continuum state with the conduction band of the Nb-SrTiO3. Once this
+continuum (metallic) state is formed, the state remains stable even when the
+voltage bias is turned off. An opposing voltage is required to deplete the
+charges from the defect states. Our ability to manipulate and control these
+defect states and, thus, the nonlinear insulating properties of complex oxides
+will open up a new path to develop novel devices.",1011.2629v1
+2020-07-27,"Plasma-assisted molecular beam epitaxy of SnO(001) films: Metastability, hole transport properties, Seebeck coefficient, and effective hole mass","Transparent conducting or semiconducting oxides are important materials for
+(transparent) optoelectronics and power electronics applications. While most of
+these oxides can be doped n-type only with room-temperature electron mobilities
+on the order of 100cm^2/Vs p-type oxides are needed for the realization of
+pn-junction devices but typically suffer from exessively low (<<1cm^2/Vs) hole
+mobilities. Tin monoxide (SnO) is one of the few p-type oxides with a higher
+hole mobility, lacking a well-established understanding of its hole transport
+properties. Moreover, growth of SnO is complicated by its metastability with
+respect to SnO2 and Sn, requiring epitaxy for the realization of single
+crystalline material typically required for high-end applications. Here, we
+give a comprehensive account on the epitaxial growth of SnO, its
+(meta)stability, and its thermoelectric transport properties in the context of
+the present literature. Textured and single-crystalline, unintentionally-doped
+p-type SnO(001) films are grown by plasma-assisted molecular beam epitaxy. The
+metastability of this semiconducting oxide is addressed theoretically through
+an equilibrium phase diagram. Experimentally, the related SnO growth window is
+rapidly determined by an in-situ growth kinetics study as function of
+Sn-to-O-plasma flux ratio and growth temperature. The presence of secondary Sn
+and SnOx (1 < x <= 2) phases is comprehensively studied by different methods,
+indicating the presence of Sn3O4 or Sn as major secondary phases, as well as a
+fully oxidized SnO2 film surface. The hole transport properties, Seebeck
+coefficient, and density-of-states effective mass are determined and critically
+discussed in the context of the present literature on SnO, considering its
+anisotropic hole-effective mass.",2007.13448v2
+2011-11-19,First-principles study on oxidation effects in uranium oxides and high-pressure high-temperature behavior of point defects in uranium dioxide,"Formation Gibbs free energy of point defects and oxygen clusters in uranium
+dioxide at high-pressure high-temperature conditions are calculated from first
+principles, using the LSDA+U approach for the electronic structure and the
+Debye model for the lattice vibrations. The phonon contribution on Frenkel
+pairs is found to be notable, whereas it is negligible for the Schottky defect.
+Hydrostatic compression changes the formation energies drastically, making
+defect concentrations depend more sensitively on pressure. Calculations show
+that, if no oxygen clusters are considered, uranium vacancy becomes predominant
+in overstoichiometric UO2 with the aid of the contribution from lattice
+vibrations, while compression favors oxygen defects and suppresses uranium
+vacancy greatly. At ambient pressure, however, the experimental observation of
+predominant oxygen defects in this regime can be reproduced only in a form of
+cuboctahedral clusters, underlining the importance of defect clustering in
+UO2+x. Making use of the point defect model, an equation of state for
+non-stoichiometric oxides is established, which is then applied to describe the
+shock Hugoniot of UO2+x. Furthermore, the oxidization and compression behavior
+of uranium monoxide, triuranium octoxide, uranium trioxide, and a series of
+defective UO2 at zero Kelvin are investigated. The evolution of mechanical
+properties and electronic structures with an increase of the oxidation degree
+are analyzed, revealing the transition of the groundstate of uranium oxides
+from metallic to Mott insulator and then to charge-transfer insulator due to
+the interplay of strongly correlated effects of 5f orbitals and the shift of
+electrons from uranium to oxygen atoms.",1111.4548v1
+2020-12-15,Oxidation Processes Diversify the Metabolic Menu on Enceladus,"The Cassini mission to the Saturn system discovered a plume of ice grains and
+water vapor erupting from cracks on the icy surface of the satellite Enceladus.
+This moon has a global ocean in contact with a rocky core beneath its icy
+exterior, making it a promising location to search for evidence of
+extraterrestrial life in the solar system. The previous detection of H$_2$ in
+the plume indicates that there is free energy available for methanogenesis, the
+metabolic reaction of H$_2$ with CO$_2$ to form methane and water. Additional
+metabolic pathways could provide sources of energy in Enceladus' ocean, but
+require the use of other oxidants that have not been detected in the plume.
+Here, we perform chemical modeling to determine how the production of
+radiolytic O$_2$ and H$_2$O$_2$, and abiotic redox chemistry in the ocean and
+rocky core, contribute to chemical disequilibria that could support metabolic
+processes in Enceladus' ocean. We consider three possible cases for ocean redox
+chemistry: Case I in which reductants are not present in appreciable amounts
+and oxidants accumulate over time, and Cases II and III in which aqueous
+reductants or seafloor minerals, respectively, convert O$_2$ and H$_2$O$_2$ to
+SO$_4^{2-}$ and ferric oxyhydroxides. We calculate the upper limits on the
+concentrations of oxidants and chemical energy available for metabolic
+reactions in all three cases, neglecting additional abiotic reactions. For all
+three cases, we find that many aerobic and anaerobic metabolic reactions used
+by microbes on Earth could meet the minimum free energy threshold required for
+terrestrial life to convert ADP to ATP, as well as sustain positive cell
+density values within the Enceladus seafloor and/or ocean. These findings
+indicate that oxidant production and oxidation chemistry could contribute to
+supporting possible life and a metabolically diverse microbial community on
+Enceladus.",2012.08582v1
+2017-05-09,Atomically flat single terminated oxide substrate surfaces,"To achieve high quality epitaxial thin films and heterostructures of
+transition metal oxides with atomically controlled interfaces, one critical
+requirement is the use of atomically flat single terminated oxide substrates
+since the atomic arrangements and the reaction chemistry of the topmost surface
+layer of substrates determine the growth and consequent properties of the
+overlying films. Achieving the atomically flat and chemically single terminated
+surface state of commercially available substrates, however, requires judicious
+efforts because the surface of as-received substrates is of chemically mixed
+nature and also often polar. In this review, we summarize the surface treatment
+procedures to accomplish atomically flat surfaces with single terminating layer
+for various metal oxide substrates. We particularly focus on the substrates
+with lattice constant ranging from 4.00 to 3.70 angstrom, as the lattice
+constant of most perovskite materials falls into this range. For materials
+outside the range, one can utilize the substrates to induce compressive or
+tensile strain on the films and explore new states not available in bulk. The
+substrates covered in this review, which have been chosen with commercial
+availability and, most importantly, experimental practicality as a criterion,
+are KTaO3, REScO3 (RE = Rare-earth elements), SrTiO3,
+La0.18Sr0.82Al0.59Ta0.41O3 (LSAT), NdGaO3, LaAlO3, SrLaAlO4, and YAlO3.
+Analyzing all the established procedures, we conclude that atomically flat
+surfaces with selective A- or B-site single termination would be obtained for
+most commercially available oxide substrates. We further note that this topmost
+surface layer selectivity would provide an additional degree of freedom in
+searching for unforeseen emergent phenomena and functional applications in
+epitaxial oxide thin films and heterostructures with atomically controlled
+interfaces.",1705.03436v2
+2017-05-10,Effect of Dynamic Surface Polarization on the Oxidative Stability of Solvents in Nonaqueous Li-O$_2$ Batteries,"Polarization-induced renormalization of the frontier energy levels of
+interacting molecules and surfaces can cause significant shifts in the
+excitation and transport behavior of electrons. This phenomenon is crucial in
+determining the oxidative stability of nonaqeous electrolytes in high energy
+density electrochemical systems such as the Li-O$_2$ battery. On the basis of
+partially self-consistent first-principles ScGW0 calculations, we
+systematically study how the electronic energy levels of four commonly used
+solvent molecules, namely dimethylsulfoxide (DMSO), dimethoxyethane (DME),
+tetrahydrofuran (THF) and acetonitrile (ACN), renormalize when physisorbed on
+the different stable surfaces of Li$_2$O$_2$, the main discharge product. Using
+band level alignment arguments, we propose that the difference between the
+solvent's highest occupied molecular orbital (HOMO) level and the surface's
+valence band maximum (VBM) is a refined metric of oxidative stability. This
+metric and a previously used descriptor, solvent's gas phase HOMO level, agree
+quite well for physisorbed cases on pristine surfaces where ACN is oxidatively
+most stable followed by DME, THF and DMSO. However, this effect is
+intrinsically linked to the surface chemistry of solvent's interaction with the
+surfaces states and defects, and depends strongly on their nature. We
+conclusively show that the propensity of solvent molecules to oxidize will be
+significantly higher on Li$_2$O$_2$ surfaces with defects as compared to
+pristine surfaces. This suggests that the oxidatively stability of solvent is
+dynamic and is a strong function of surface electronic properties. Thus, while
+gas phase HOMO levels could be used for preliminary solvent candidate
+screening, a more refined picture of solvent stability requires mapping out the
+solvent stability as a function of the state of the surface under the operating
+conditions.",1705.03862v1
+2019-08-27,A combinatorial guide to phase formation and surface passivation of tungsten titanium oxide prepared by thermal oxidation,"TiO$_2$ and WO$_3$ are two of the most important earth-abundant electronic
+materials with applications in countless industries. Recently alloys of WO$_3$
+and TiO$_2$ have been investigated leading to improvements of key performance
+indicators for a variety of applications ranging from photo-electrochemical
+water splitting to electrochromic smart windows. These positive reports and the
+complexity of the ternary W-Ti-O phase diagram motivate a comprehensive
+experimental screening of this phase space. Using combinatorial thermal
+oxidation of solid solution W$_{1-x}$Ti$_{x}$ precursors combined with bulk and
+surface analysis mapping we investigate the oxide phase formation and surface
+passivation of tungsten titanium oxide in the entire compositional range from
+pure WO$_3$ to TiO$_2$. The system shows a remarkable structural transition
+from monoclinic over cubic to tetragonal symmetry with increasing Ti
+concentration. In addition, a strong Ti surface enrichment is observed for
+precursor Ti-concentrations in excess of 55 at.%, resulting in the formation of
+a protective rutile-structured TiO$_2$ surface layer. Despite the structural
+transitions, the optical properties of the oxide alloys remain largely
+unaltered demonstrating an independent control of multiple functional
+properties in W$_{1-x}$Ti$_{x}$O$_{n}$. The results from this study provide
+valuable guidelines for future development of W$_{1-x}$Ti$_{x}$O$_{n}$ for
+electronic and energy applications, but also novel engineering approaches for
+surface functionalization and additive manufacturing of Ti-based alloys.",1908.10067v1
+2020-05-19,"Post-mortem analysis of tungsten plasma facing components in tokamaks: Raman microscopy measurements on compact, porous oxide and nitride films and nanoparticles","Raman microscopy is one of the methods that could be used for future
+post-mortem analyses of samples extracted from ITER plasma facing. This study
+shows that this technique is useful for studying tungsten-based materials
+containing impurities including oxides and nitrides. Here, we apply pulsed
+laser deposition and DC argon glow discharges to produce tungsten-containing
+synthetic films (compact, porous) and nanoparticles and investigate the
+influence of their morphology on the measured Raman spectra. The amounts of
+oxygen and/or nitrogen in the films are also investigated. Comparative data are
+obtained by X-ray Photoelectrons Spectroscopy, Atomic Force Microscopy,
+Electron Microscopies (Scanning and Transmission), Energy Dispersive X-ray
+spectroscopy, Time-of-Flight Elastic Recoil Detection Analysis. The power
+density of the laser beam used to perform Raman microscopy is varied by up to 4
+orders of magnitude (0.01-20 mW/$\mu$m 2) to investigate thermal stability of
+films and nanoparticles. As a first result, we give evidence that Raman
+microscopy is sensitive enough to detect surface native oxides. Secondly, more
+tungsten oxides are detected in porous materials and nanoparticles than in
+compact films, and the intensities of the Raman band correlate to their oxygen
+content. Thirdly, thermal stability of these films (i.e. structural and
+chemical modification under laser heating) is poor when compact films contain a
+sufficiently large amount of nitrogen. This finding suggests that nitrogen can
+be substituted by oxygen during Raman laser induced heating occurring in
+ambient air. Finally, our methodology can be used to rapidly characterize
+morphology and chemistry of the samples analyzed, and also to create oxides at
+the micrometer scale. keywords: PLD, Raman spectroscopy, tungsten oxide,
+tungsten nitride, plasma wall interaction, laser heating, post-mortem analysis
+2",2005.09295v1
+2020-06-30,High-Voltage Honeycomb Layered Oxide Positive Electrodes for Rechargeable Sodium Batteries,"Natural abundance, impressive chemical characteristics and economic
+feasibility have rekindled the appeal for rechargeable sodium (Na) batteries as
+a practical solution for the growing energy demand, environmental
+sustainability and energy independence. However, the scarcity of viable
+positive electrode materials remains a huge impediment to the actualization of
+this technology. In this paper, we explore honeycomb layered oxides adopting
+the composition Na$_2$Ni$_{2-x}$Co$_x$TeO$_6$ ($x = 0, 0.25$ and $0.50$) as
+feasible positive electrode (cathode) materials for rechargeable sodium
+batteries at both room- and elevated temperatures using ionic liquids. Through
+standard galvanostatic assessments and analyses we demonstrate that
+substitution of nickel with cobalt in Na$_2$Ni$_2$TeO$_6$ leads to an increase
+in the discharge voltage to nearly $4$ V (versus Na$^+$ / Na) for the
+Na$_2$Ni$_{2-x}$Co$_x$TeO$_6$ family of honeycomb layered oxide materials,
+which surpasses the attained average voltages for most layered oxide positive
+electrode materials that facilitate Na-ion desertion. We also verify the
+increased kinetics within the Na$_2$Ni$_{2-x}$Co$_x$TeO$_6$ honeycomb layered
+oxides during operations at elevated temperatures which lead to an increase in
+reversible capacity of the rechargeable Na battery. This study underpins the
+doping of congener transition metal atoms to the honeycomb structure of
+Na$_2$Ni$_2$TeO$_6$ in addition to elevated-temperature operation as a
+judicious route to enhance the electrochemical performance of analogous layered
+oxides.",2006.16656v1
+2021-02-19,Thermal and Oxidation Stability of Ti$_x$W$_{1-x}$ Diffusion Barriers Investigated by Soft and Hard X-ray Photoelectron Spectroscopy,"The binary alloy of titanium-tungsten (TiW) is an established diffusion
+barrier in high-power semiconductor devices, owing to its ability to suppress
+the diffusion of copper from the metallisation scheme into the surrounding
+silicon substructure. However, little is known about the response of TiW to
+high temperature events or its behaviour when exposed to air. Here, a combined
+soft and hard X-ray photoelectron spectroscopy (XPS) characterisation approach
+is used to study the influence of post-deposition annealing and titanium
+concentration on the oxidation behaviour of a 300~nm-thick TiW film. The
+combination of both XPS techniques allows for the assessment of the chemical
+state and elemental composition across the surface and bulk of the TiW layer.
+The findings show that in response to high-temperature annealing, titanium
+segregates out of the mixed metal system and upwardly migrates, accumulating at
+the TiW/air interface. Titanium shows remarkably rapid diffusion under
+relatively short annealing timescales and the extent of titanium surface
+enrichment is increased through longer annealing periods or by increasing the
+precursor titanium concentration. Surface titanium enrichment enhances the
+extent of oxidation both at the surface and in the bulk of the alloy due to the
+strong gettering ability of titanium. Quantification of the soft X-ray
+photoelectron spectra highlights the formation of three tungsten oxidation
+environments, attributed to WO$_2$, WO$_3$ and a WO$_3$ oxide coordinated with
+a titanium environment. This combinatorial characterisation approach provides
+valuable insights into the thermal and oxidation stability of TiW alloys from
+two depth perspectives, aiding the development of future device technologies.",2102.09845v1
+2021-10-29,Spatially-Modulated Silicon Interface Energetics via Hydrogen Plasma-Assisted Atomic Layer Deposition of Ultrathin Alumina,"Atomic layer deposition (ALD) is a key technique for the continued scaling of
+semiconductor devices, which increasingly relies on reproducible and scalable
+processes for interface manipulation of 3D structured surfaces on the atomic
+scale. While ALD allows the synthesis of conformal films at low temperature
+with utmost control over the thickness, atomically-defined closed coatings and
+surface modifications are still extremely difficult to achieve because of
+three-dimensional growth during nucleation. Here, we present a route towards
+sub-nanometer thin and continuous aluminum oxide (AlOx) coatings on silicon
+(Si) substrates for the spatial control of the surface charge density and
+interface energetics. We use trimethylaluminum (TMA) in combination with remote
+hydrogen plasma instead of a gas-phase oxidant for the transformation of
+silicon oxide into alumina (AlOx). During the initial ALD cycles, TMA reacts
+with the surface oxide (SiO2) on silicon until there is a saturation of
+bindings sites, after which the oxygen from the underlying surface oxide is
+consumed, thereby transforming the silicon oxide into Si capped with AlOx.
+Depending on the number of ALD cycles, the SiO2 can be partially or fully
+transformed, which we exploit to create sub-nanometer thin and continuous AlOx
+layers deposited in selected regions defined by lithographic patterning. The
+resulting patterned surfaces are characterized by lateral AlOx/SiO2 interfaces
+possessing step heights as small as 0.3 nm and surface potential steps in
+excess of 0.4 V. In addition, the introduction of fixed negative charges of $9
+\times 10^{12}$ cm$^{-2}$ enables modulation of the surface band bending, which
+is relevant to the field-effect passivation of Si and low-impedance charge
+transfer across contact interfaces.",2111.00054v2
+2023-02-27,Engineering of Niobium Surfaces Through Accelerated Neutral Atom Beam Technology For Quantum Applications,"A major roadblock to scalable quantum computing is phase decoherence and
+energy relaxation caused by qubits interacting with defect-related two-level
+systems (TLS). Native oxides present on the surfaces of superconducting metals
+used in quantum devices are acknowledged to be a source of TLS that decrease
+qubit coherence times. Reducing microwave loss by surface engineering (i.e.,
+replacing uncontrolled native oxide of superconducting metals with a thin,
+stable surface with predictable characteristics) can be a key enabler for
+pushing performance forward with devices of higher quality factor. In this
+work, we present a novel approach to replace the native oxide of niobium
+(typically formed in an uncontrolled fashion when its pristine surface is
+exposed to air) with an engineered oxide, using a room-temperature process that
+leverages Accelerated Neutral Atom Beam (ANAB) technology at 300 mm wafer
+scale. This ANAB beam is composed of a mixture of argon and oxygen, with
+tunable energy per atom, which is rastered across the wafer surface. The
+ANAB-engineered Nb-oxide thickness was found to vary from 2 nm to 6 nm
+depending on ANAB process parameters. Modeling of variable-energy XPS data
+confirm thickness and compositional control of the Nb surface oxide by the ANAB
+process. These results correlate well with those from transmission electron
+microscopy and X-ray reflectometry. Since ANAB is broadly applicable to
+material surfaces, the present study indicates its promise for modification of
+the surfaces of superconducting quantum circuits to achieve longer coherence
+times.",2302.14113v1
+2023-03-20,Machine learning assisted phase and size-controlled synthesis of iron oxides,"The controllable synthesis of iron oxides particles is a critical issue for
+materials science, energy storage, biomedical applications, environmental
+science, and earth science. However, synthesis of iron oxides with desired
+phase and size are still a time-consuming and trial-and-error process. This
+study presents solutions for two fundamental challenges in materials synthesis:
+predicting the outcome of a synthesis from specified reaction parameters and
+correlating sets of parameters to obtain products with desired outcomes. Four
+machine learning algorithms, including random forest, logistic regression,
+support vector machine, and k-nearest neighbor, were trained to predict the
+phase and particle size of iron oxide based on experimental conditions. Among
+the models, random forest exhibited the best performance, achieving 96% and 81%
+accuracy when predicting the phase and size of iron oxides in the test dataset.
+Premutation feature importance analysis shows that most models (except logistic
+regression) rely on known features such as precursor concentration, pH, and
+temperature to predict the phases from synthesis conditions. The robustness of
+the random forest models was further verified by comparing prediction and
+experimental results based on 24 randomly generated methods in additive and
+non-additive systems not included in the datasets. The predictions of product
+phase and particle size from the models are in good agreement with the
+experimental results. Additionally, a searching and ranking algorithm was
+developed to recommend potential synthesis parameters for obtaining iron oxide
+products with desired phase and particle size from previous studies in the
+dataset.",2303.11244v1
+2023-10-31,"Electronic structure study of YNbTiO$_6$ vs. CaNb$_2$O$_6$ with U, Pu and minor actinide substitutions using compound-tunable embedding potential method","The compound-tunable embedding potential (CTEP) method is applied to study
+actinide substitutions in the niobate crystals YNbTiO$_6$ and CaNb$_2$O$_6$.
+Two one-center clusters centered on Ca and Y are built and 20 substitutions of
+Ca and Y with U, Np, Pu, Am, and Cm in four different oxidation states were
+made for each cluster. Geometry relaxation is performed for each resulting
+structure, and electronic properties are analyzed by evaluating the spin
+density distribution and X-ray emission spectra chemical shifts. Though the
+studied embedded clusters with actinides having the same oxidation state are
+found in general to yield similar local structure distortions, for Am and Cm in
+high ""starting"" oxidation states the electron transfer from the environment was
+found, resulting in decrease of their oxidation states, while for ""starting""
+U$^{\rm III}$ state the electron transfer goes in the opposite direction,
+resulting in increase of its oxidation state to U$^{\rm IV}$.
+  The U substitutions are additionally studied with the use of multi-center
+models, which can provide both more structural and electronic relaxation and
+also include charge-compensating vacancies. For ""starting"" U$^{\rm VI}$ case,
+the decrease in oxidation state similar to that of Am$^{\rm VI}$ and Cm$^{\rm
+VI}$ in one-center clusters is observed in our calculations but in a different
+way.
+  Since the really synthesized YNbTiO$_6$ structures can not be considered as
+perfect (periodic) crystals because the Nb and Ti atoms are statistically
+distributed within them occupying the same Wyckoff positions, different Ti
+$\leftrightarrow$ Nb substitutions are studied and corresponding structural
+changes are estimated.",2310.20595v1
+2023-12-18,Computational insights into phase equilibria between wide-gap semiconductors and contact materials,"Novel wide-band-gap semiconductors are needed for next-generation power
+electronic but there is a gap between a promising material and a functional
+device. Finding stable contacts is one of the major challenges, which is
+currently dealt with mainly via trial and error. Herein, we computationally
+investigate the thermochemistry and phase co-existence at the junction between
+three wide gap semiconductors, $\beta$-Ga$_{2}$O$_{3}$, GeO$_2$, and GaN, and
+possible contact materials. The pool of possible contacts includes 47 elemental
+metals and 4 common $n$-type transparent conducting oxides (ZnO, TiO$_2$,
+SnO$_2$, and In$_2$O$_3$). We use first-principles thermodynamics to model the
+Gibbs free energies of chemical reactions as a function of the gas pressure
+(p$_{\mathrm{O}_2}$/p$_{\mathrm{N}_2}$) and equilibrium temperature. We deduce
+whether a semiconductor/contact interface will be stable at relevant
+conditions, possibly influencing the long-term reliability and performance of
+devices. We generally find that most elemental metals tend to oxidize or
+nitridize and form various interface oxide/nitride layers. Exceptions include
+select late- and post-transition metals, and in case of GaN also the alkali
+metals, which are predicted to exhibit stable coexistence, although in many
+cases at relatively low gas partial pressures. Similar is true for the
+transparent conducting oxides, for which in most cases we predict a preference
+toward forming ternary oxides when in contact with $\beta$-Ga$_{2}$O$_{3}$ and
+GeO$_{2}$. The only exception is SnO$_2$, which can form stable contacts with
+both oxides. Finally, we show how the same approach can be used to predict gas
+partial pressure vs. temperature phase diagrams to help direct synthesis of
+ternary compounds. We believe these results provide a valuable guidance in
+selecting contact materials to wide-gap semiconductors and suitable growth
+conditions.",2312.11749v1
+2024-02-01,Exploring inverse orbital Hall and orbital Rashba effects: unveiling the oxidation states of the Cu surface,"In this work, employing spin-pumping techniques driven by both ferromagnetic
+resonance (SP-FMR) and longitudinal spin Seebeck effect (LSSE) to manipulate
+and direct observe orbital currents, we investigated the volume conversion of
+spin-orbital currents into charge-current in YIG(100nm)/Pt(2nm)/NM2 structures,
+where NM2 represents Ti or Ru. While the YIG/Ti bilayer displayed a negligible
+SP-FMR signal, the YIG/Pt/Ti structure exhibited a significantly stronger
+signal attributed to the orbital Hall effect of Ti. Substituting the Ti layer
+with Ru revealed a similar phenomenon, wherein the effect is ascribed to the
+combined action of both spin and orbital Hall effects. Furthermore, we measured
+the SP-FMR signal in the YIG/Pt(2)/Ru(6)/Ti(6) and YIG/Pt(2)/Ti(6)/Ru(6)
+heterostructures by just altering the stack order of Ti and Ru layers, where
+the peak value of the spin pumping signal is larger for the first sample. To
+verify the influence on the oxidation of Ti and Ru films, we studied a series
+of thin films subjected to controlled and natural oxidation. As Cu and CuOx is
+a system that is already known to be highly influenced by oxidation, this metal
+was chosen to carry out this study. We investigated these samples using SP-FMR
+in YIG/Pt(2)/CuOx(tCu) and X-ray absorption spectroscopy and concluded that
+samples with natural oxidation of Cu exhibit more significant results than
+those when the CuOx is obtained by reactive sputtering. In particular, samples
+where the Cu layer is naturally oxidized exhibit a Cu2O-rich phase. Our
+findings help to elucidate the mechanisms underlying the inverse orbital Hall
+and inverse orbital Rashba-Edelstein-like effects. These insights indeed
+contribute to the advancement of devices that rely on orbital-charge
+conversion.",2402.00297v1
+1998-07-15,Driven Morse Oscillator: Model for Multi-photon Dissociation of Nitrogen Oxide,"Within a one-dimensional semi-classical model with a Morse potential the
+possibility of infrared multi-photon dissociation of vibrationally excited
+nitrogen oxide was studied. The dissociation thresholds of typical driving
+forces and couplings were found to be similar, which indicates that the results
+were robust to variations of the potential and of the definition of
+dissociation rate.
+  PACS: 42.50.Hz, 33.80.Wz",9807020v1
+1995-01-05,Two-Color Coherent Photodissociation of Nitrogen Oxide in Intense Laser Fields,"A simple one-dimensional semi-classical model with a Morse potential is used
+to investigate the possibility of two-color infrared multi-photon dissociation
+of vibrationally excited nitrogen oxide. The amplitude ratio effects and
+adiabatic effects are investigated. Some initial states are found to have
+thresholds smaller than expected from single-mode considerations and multiple
+thresholds exist for initial states up to 32.
+  PACS: 42.50.Hz",9501001v2
+1994-01-02,Driven Morse Oscillator: Model for Multi-photon Dissociation of Nitrogen Oxide,"Within a one-dimensional semi-classical model with a Morse potential the
+possibility of microwave multi-photon dissociation of vibrationally excited
+nitrogen oxide was studied. The dissociation thresholds of typical driving
+forces and couplings were found to be similar, which indicates that the results
+were robust to variations of the potential and the definition of dissociation
+rate.",9312098v1
+1994-03-16,Asymptotically exact solution of a local copper-oxide model,"We present an asymptotically exact solution of a local copper-oxide model
+abstracted from the multi-band models. The phase diagram is obtained through
+the renormalization-group analysis of the partition function. In the strong
+coupling regime, we find an exactly solved line, which crosses the quantum
+critical point of the mixed valence regime separating two different
+Fermi-liquid (FL) phases. At this critical point, a many-particle resonance is
+formed near the chemical potential, and a marginal-FL spectrum can be derived
+for the spin and charge susceptibilities.",9403059v1
+1994-07-13,Large Phase Separation and Superconductivity in the Copper Oxide Chain,"The phase diagram of the copper-oxide chain as a function of density and the
+nearest-neighbour Coulomb interaction, V, is determined. Phase separation takes
+place above a critical value of $V$ when the Cu2+ to Cu+ valence fluctuations
+dominate. In the proximity of the phase separation boundary the superconducting
+correlations are the most divergent. We identify the parameter regions where
+the Luttinger Liquid theory applies and calculate the contours of the
+charge-charge correlation exponent K_{\rho}. We show that anomalous flux
+quantization occurs as K_{\rho} diverges. At n = 1, for V > t, a gap opens in
+the spectrum and the ground state is a charge-density wave.",9407064v1
+1994-07-13,Phase Separation and Superconductivity in the Copper Oxide Chain,"The phase diagram of the copper-oxide chain as a function of density and the
+nearest-neighbour Coulomb interaction, V, is determined. Phase separation takes
+place above a critical value of $V$ when the Cu2+ to Cu+ valence fluctuations
+dominate. In the proximity of the phase separation boundary the superconducting
+correlations are the most divergent. We identify the parameter regions where
+the Luttinger Liquid theory applies and calculate the contours of the
+charge-charge correlation exponent K_{\rho}. We show that anomalous flux
+quantization occurs as$K_{\rho} diverges. At n = 1, for V > t, a gap opens in
+the spectrum and the ground state is a charge-density wave.",9407067v1
+1996-05-31,c axis superfluid response of Copper-Oxide superconductors,"A novel interplay between d-wave superconducting order parameter symmetry and
+the underlying Cu 3d orbital based electronic structure of Copper-Oxides leads
+to a striking anisotropy in the superfluid response of these systems. In clean
+tetragonal materials the c-axis penetration depth increases as T^5 at low
+temperature T, in contrast to linear T behavior in the ab-plane. Disorder is a
+relevant perturbation which causes all components of the superfluid response to
+depend quadratically on temperature at low temperature. However, the cross-over
+temperature scale from the intrinsic d-wave behavior to the disorder dominated
+behavior for the in-plane response may be different from that for the out-plane
+response.",9605196v1
+1996-08-06,Evolution of photoemission spectral functions in doped transition metal oxides,"We discuss the experimental photoemission and inverse photoemission of early
+transition metal oxides, in the light of the dynamical mean field theory of
+correlated electrons which becomes exact in the limit of infinite dimensions.
+We argue that a comprehensive description of the experimental data requires
+spatial inhomogeneities and present a calculation of the evolution of the
+spectral function in an inhomogenous system with various degrees of
+inhomogeneity. We also point out that comparaison of experimental results and
+large d calculations require that the degree of correlation and disorder is
+larger in the surface than in the bulk.",9608021v1
+1997-02-04,Anomalous Behavior of Ru for Catalytic Oxidation: A Theoretical Study of the Catalytic Reaction CO + 1/2 O_2 --> CO_2,"Recent experiments revealed an anomalous dependence of carbon monoxide
+oxidation at Ru(0001) on oxygen pressure and a particularly high reaction rate.
+Below we report density functional theory calculations of the energetics and
+reaction pathways of the speculated mechanism. We will show that the
+exceptionally high rate is actuated by a weakly but nevertheless well bound
+(1x1) oxygen adsorbate layer. Furthermore it is found that reactions via
+scattering of gas-phase CO at the oxygen covered surface may play an important
+role. Our analysis reveals, however, that reactions via adsorbed CO molecules
+(the so-called Langmuir-Hinshelwood mechanism) dominate.",9702040v1
+1997-02-10,Non-Nominal Value of the Dynamical Effective Charge in Alkaline-Earth Oxides,"We calculate ab-initio the electronic states and the Born dynamical charge Z*
+of the alkaline-earth oxides in the local-density approximation. We investigate
+the trend of increasing Z* values through the series, using band-by-band
+decompositions and computational experiments performed on fake materials with
+artificially-modified covalence. The deviations of Z* from the nominal value 2
+are due to the increasing interaction between O 2p orbitals and unoccupied
+cation d states. We also explain the variations, along the series, of the
+individual contributions to Z* arising from the occupied band manifolds.",9702086v1
+1997-02-26,Formation of localized hole states in complex oxides,"Defect electrons (holes) play an important role in most technologically
+important complex oxides; many of which possess perovskite-related structures.
+In this contribution we present the first detailed characterization of
+localized hole states in such materials. Our investigations employ advanced
+embedded-cluster calculations which consistently include electron correlations
+and defect-induced lattice relaxations. This is necessary in order to account
+for the variety of possible hole-state manifestations.",9702223v1
+1997-08-21,Charge Dynamics from Copper Oxide Materials,"The charge dynamics of the copper oxide materials in the underdoped and
+optimal doped regimes is studied within the framework of the fermion-spin
+theory. The conductivity spectrum shows the non-Drude behavior at low energies
+and unusual midinfrared peak, and the resistivity exhibits a linear behavior in
+the temperature, which are consistent with experiments and numerical
+simulations.",9708165v2
+1998-03-20,Universal Spin Response in Copper Oxide Materials,"The spin response in the copper oxide materials at finite temperatures in the
+underdoped and optimal doped regimes is studied within the framework of the
+fermion-spin theory. The integrated dynamical spin structure factor is almost
+temperature independent, the integrated susceptibility shows the particularly
+universal behavior as $I(\omega, T) \propto arctan [ a_{1}\omega/T +
+a_{3}(\omega/T)^{3}]$, and the spin-lattice relaxation time is weakly
+temperature dependent, which are consistent with experiments and numerical
+simulations.",9803246v2
+1998-11-28,Low energy excitations in crystalline perovskite oxides: Evidence from noise experiments,"In this paper we report measurements of 1/f noise in a crystalline metallic
+oxide with perovskite structure down to 4.2K. The results show existence of
+localized excitations with average activation energy $\approx$ 70-80 meV which
+produce peak in the noise at T $\approx$ 35-40K. In addition, it shows clear
+evidence of tunnelling type two-level-systems (as in glasses) which show up in
+noise measurements below 30K.",9811398v1
+1998-12-08,On a biphononic origin of the 1125 cm^(-1) absorption band in cuprous oxide,"We report on the IR spectroscopic studies in both reflection (50-900 cm^{-1})
+and transmission (900-3000 cm^{-1}) mode of the vibration spectrum of the
+cuprous oxide. A detailed analysis based on a comparison of the temperature
+dependences of the absorption band at 1125 cm^{-1} and of IR and Raman active
+fundamental vibrations results in assignment of the former to a biphonon.",9812122v3
+1998-12-22,Modified Double Exchange Model with Novel Spin and Orbital Coupling: Phase Diagram of The Manganites,"From a general model of the Mn oxides R_{1-x}A_{x}MnO_3, we derive an
+effective Hamiltonian in the low-energy subspace using the projection operator
+method, in which a novel coupling between the spin and orbital degrees of
+freedom is included. A phase diagram for temperature T versus doping
+concentration x is computed by means of Monte Carlo simulation. Our result is
+consistent with experimental observations in the Mn oxides with relatively wide
+conduction band, such as Pr_{1-x}Sr_{x} MnO_{3} and La_{1-x}Sr_{x}MnO_{3}.
+According to the obtained orbital ordering, we also predict that the motion of
+charge carriers transforms from three-dimensional to two-dimensional as x is
+increased beyond a critical value.",9812374v1
+1999-02-16,Forward Electron-Phonon Scattering and HTS,"Tunneling and point contact spectroscopy show clear phonon features and
+together with optic measurements give strong support that the electron-phonon
+interaction (EPI) is large in HTS oxides. Strong correlations in HTS oxides
+renormalize the EPI (and interaction with impurities) so that the forward
+scattering peak (FSP) develops for small hole doping \delta<<1. The FSP
+mechanism explains important properties of the normal and superconducting
+state.",9902232v1
+1999-03-20,Comparison of superconductivity in Sr_2RuO_4 and copper oxides,"To compare the superconductivity in strongly correlated electron systems with
+the antiferromagnetic fluctuations in the copper oxides and with the
+ferromagnetic fluctuations in Sr_2RuO_4 a t-J-I model is proposed. The
+antiferromagnetic coupling J results in the superconducting state of
+d_{x^2-y^2} symmetry and the ferromagnetic coupling constant I results in the
+spin-triplet p-type state. The difference in the gap anisotropies provides the
+large difference in T_c values, for the typical values of the coupling
+constants: T_c of order of 1K for the ruthenate and T_c of order of 100K for
+the cuprates.",9903314v1
+1999-05-28,Energetics of the oxidation and opening of a carbon nanotube,"We apply first principles calculations to study the opening of single-wall
+carbon nanotubes (SWNT's) by oxidation. We show that an oxygen rim can
+stabilize the edge of the open tube. The sublimation of CO$_2$ molecules from
+the rim with the subsequent closing of the tube changes from endothermic to
+exothermic as the tube radius increases, within the range of experimental
+feasible radii. We also obtain the energies for opening the tube at the cap and
+at the wall, the latter being significantly less favorable.",9905419v1
+2000-04-13,Oscillatory Exchange Coupling and Positive Magnetoresistance in Epitaxial Oxide Heterostructures,"Oscillations in the exchange coupling between ferromagnetic
+$La_{2/3}Ba_{1/3}MnO_3$ layers with paramagnetic $LaNiO_3$ spacer layer
+thickness has been observed in epitaxial heterostructures of the two oxides.
+This behavior is explained within the RKKY model employing an {\it ab initio}
+calculated band structure of $LaNiO_3$, taking into account strong electron
+scattering in the spacer. Antiferromagnetically coupled superlattices exhibit a
+positive current-in-plane magnetoresistance.",0004230v1
+2000-04-18,"Momentum and doping dependence of the electron spectrum and ($π$,0) feature in copper oxide materials","The momentum and doping dependence of the electron spectrum of copper oxide
+materials in the underdoped regime is studied within the t-J model. It is shown
+that the pseudogap opens near ($\pi$,0) point in the Brillouin zone, and the
+electron dispersion exhibits the flat band around ($\pi$,0), which are
+consistent with the experiments.",0004299v1
+2000-11-14,Nature of traps responsible for failure of MOS devices,"A failure of chips in a huge amount of modern electronic devices is connected
+as a rule with the undesirable capturing of charge (electrons and holes) by
+traps in a thin insulating film of silicon oxide in transistors. It leads to a
+breakdown of transistors or to a destructive change of their characteristics.
+It is suggested that silicon oxide will be replaced in the next generation of
+nanoscale devices by silicon oxynitride. Therefore, it is very important to
+understand the nature of traps in this material. We discuss this nature using
+the quantum-chemical simulation.",0011241v1
+2001-05-23,CO oxidation on a single Pd atom supported on magnesia,"The oxidation of CO on single Pd atoms anchored to MgO(100) surface oxygen
+vacancies is studied with temperature-programmed-reaction mass-spectrometry and
+infrared spectroscopy. In one-heating-cycle experiments CO$_2$, formed from
+O$_2$ and CO preadsorbed at 90 K, is detected at 260 K and 500 K. Ab-initio
+simulations suggest two reaction routes, with Pd(CO)$_2$O$_2$ and Pd(CO$_3$)CO
+found as precursors for the low and high temperature channels, respectively.
+Both reactions result in annealing of the vacancy and induce migration and
+coalescence of the remaining Pd-CO to form larger clusters.",0105460v1
+2001-07-10,Titanium single electron transistor fabricated by electron-beam lithography,"A new method to fabricate non-superconducting mesoscopic tunnel junctions by
+oxidation of Ti is presented. The fabrication process uses conventional
+electron beam lithography and shadow deposition through an organic resist mask.
+Superconductivity in Ti is suppressed by performing the deposition under a
+suitable background pressure. We demonstrate the method by making a single
+electron transistor which operated at $T < 0.4$ K and had a moderate charge
+noise of $2.5 \times 10^{-3}$ e/$\sqrt{\mathrm{Hz}}$ at 10 Hz. Based on
+nonlinearities in the current-voltage characteristics at higher voltages, we
+deduce the oxide barrier height of approximately 110 mV.",0107199v1
+2001-08-02,Theory of Raman Scattering from Orbital Excitations in Manganese Oxides,"We present a theory of the Raman scattering from the orbital wave excitations
+in manganese oxides. Two excitation processes of the Raman scattering are
+proposed. The Raman scattering cross section is formulated by using the
+pseudospin operator for orbital degree of freedom in a Mn ion. The Raman
+spectra from the orbital wave excitations are calculated and their implications
+in the recent experimental results reported in LaMnO$_3$ are discussed.",0108032v2
+2001-08-21,Thermal conductivity of the A_xBO_2 type layered oxides Na_0.77MnO_2 and LiCoO_2,"We prepared polycrystalline samples of the A_xBO_2 type layered oxides
+Na_0.77MnO_2 and LiCoO_2, and measured thermal conductivity from 15 to 280 K.
+Na0.77MnO_2 shows a low thermal conductivity of 15 mW/cmK, while LiCoO_2 shows
+a much higher value of 40 mW/cmK at 280 K. By comparing them with the data of
+NaCo_2O_4, we have found that the low thermal conductivity of A_xBO_2 comes
+essentially from the A-ion deficiency, not from the layered structure itself.",0108327v1
+2002-01-08,Electronic structure and tunneling resonance spectra of nanoscopic aluminum islands,"The electronic structure of nanoscopic oxide-coated aluminum islands is
+investigated using a tight-binding model that incorporates the geometry,
+chemistry and disorder of the particle. The oxide coat is found to
+significantly increase the volume accessible to electrons at the Fermi level.
+The level statistics agree with random matrix theory predictions. States near
+the Fermi level show pronounced clustering regardless of disorder. It is
+suggested that the observed clusters of tunneling resonances may have a more
+complex origin than if they were solely due to many-body non-equilibrium
+effects.",0201086v1
+2002-03-08,The second phase transition in the pyrochlore oxide Cd2Re2O7,"Evidence for another phase transition at 120 K in the metallic pyrochlore
+oxide Cd2Re2O7, following the structural transition at 200 K and followed by
+the superconducting transition at 1.0 K, is given through resistivity,
+magnetoresistance, specific heat, and X-ray diffraction measurements. The
+results indicate unique successive structural and electronic transitions
+occurring in the pyrochlore compound, revealing an interesting interplay
+between the crystal and electronic structures on the itinerant electron system
+in the pyrochlore lattice.",0203178v1
+2002-04-27,A Percolative Model of Soft Breakdown in Ultrathin Oxides,"The degradation of ultrathin oxide layers in the presence of a stress voltage
+is modeled in terms of two antagonist percolation processes taking place in a
+random resistor network. The resistance and leakage current fluctuations are
+studied by MonteCarlo simulations for voltages below the breakdown threshold.
+An increase of excess noise together with a noticeable non-Gaussian behavior is
+found in the pre-breakdown regime in agreement with experimental results.",0204586v1
+2002-05-13,Pseudogap effects on the charge dynamics in the underdoped copper oxide materials,"Within the t-J model, the charge dynamics of copper oxide materials in the
+underdoped regime is studied based on the fermion-spin theory. It is shown that
+both in-plane charge dynamics and c-axis charge dynamics are mainly governed by
+the scattering from the in-plane fluctuation, which would be suppressed when
+the holon pseudogap opens at low temperatures, leading to the temperature
+linear to the nonlinear range in the in-plane resistivity and crossovers to the
+semiconducting-like range in the c-axis resistivity.",0205248v1
+2002-07-12,Transport properties and electronic states of the thermoelectric oxide NaCo_2O_4,"Physical properties of the thermoelectric oxide NaCo_2O_4 are briefly
+reviewed. The high thermoelectric properties of this material are attributed to
+the substantially enhanced effective mass, which comes from the large entropy
+of Co$^{4+}$ in the low spin state. The large entropy confined in the CoO_2
+block causes a spin-density-wave transition at 22 K upon Cu substitution for
+Co, which can be regarded as ``order from disorder''.",0207315v1
+2002-07-20,Low Temperature Symmetry of Pyrochlore Oxide Cd2Re2O7,"We report the X-ray study for the pyrochlore oxide Cd2Re2O7. Two
+symmetry-lowering structural transitions were observed at Ts1=200K and
+Ts2=120K. The former is of the second order from the ideal cubic pyrochlore
+structure with space group Fd-3m to a tetragonally distorted structure with
+I-4m2, while the latter is of the first order likely to another tetragonal
+space group I4122. We discuss the feature of the lattice deformation.",0207497v2
+2002-10-02,Anomalous Pd substitution effects in the thermoelectric oxide NaCo_{2-x}Pd_xO_4,"We prepared a set of polycrystalline samples of the thermoelectric oxide
+NaCo_{2-x}Pd_xO_4 (x= 0, 0.05, 0.1 and 0.2), and investigated the Pd
+substitution effects on transport phenomena. The effects are so drastic that
+only 5-10% Pd ions reduce the resistivity and the Seebeck coefficient to
+one-third of the values for x=0, and increase the magnitude of the Hall
+coefficient by three times. A semi-quantitative analysis has revealed that the
+x=0.2 sample has much smaller effective mass and carrier concentration than the
+x=0.05 sample. This is difficult to explain within a rigid-band picture, and is
+qualitatively consistent with a strong-correlation picture applied to the
+Ce-based heavy fermion systems.",0210043v1
+2002-10-31,A new synchronization mechanism via Turing-like microscopic structures for CO oxidation on Pt(110),"We discuss an alternative to the traditional gas-phase coupling approach in
+order to explain synchronized global oscillations in CO oxidation on Pt(110).
+We use a minimalist microscopic model which includes structural Pt surface
+reconstruction via front propagation, and large diffusion rates for CO. The
+synchronization mechanism is associated with the formation of a Turing-like
+structure of the substrate. By using large parallel microscopic simulations we
+derive a scaling laws which allow us to extrapolate to realistic diffusion
+rates, pattern size, and oscillation periods.",0210699v1
+2002-11-22,Correlations and Semimetallic Behaviors in Pyrochlore Oxide Cd2Re2O7,"Electronic properties of the metallic pyrochlore oxide Cd2Re2O7 are studied
+by means of electrical resistivity and Hall measurements. Semimetallic band
+structures are revealed as expected from band structure calculations. It is
+found that large changes in carrier density and mass occur at the structural
+phase transition at Ts1 = 200 K. A large mass enhancement is observed,
+particularly for the high-temperature phase with the ideal pyrochlore
+structure, suggesting that an anomalous correlation has an important effect on
+the itinerant electrons in the pyrochlore lattice.",0211517v1
+2002-12-22,Changes in the surface electronic structure upon martensitic transformation in TiNi and TiPd,"The electronic structure of some low index surfaces for martensitic B19'-TiNi
+and B19-TiPd were investigated using the full-potential linearized augmented
+plane wave method. The alteration of the electronic structure upon martensitic
+transformation on the surface were analyzed. According to the surface
+calculations only insignificant changes in the electronic structure near the
+Fermi level were found as for bulk ground state. The formation of oxides top
+layers is also discussed. It is shown that the influence of TiNi substrate is
+insignificant when three oxides layers are formed.",0212553v1
+2003-01-21,Charge ordering in oxides : a conundrum solved by resonant diffraction,"We show that in mixed-valence 3d transition metal oxides undergoing a
+structural transition, the low temperature phase results from an effective
+ordering of the charge. This arrangement and the quantitative evaluation of the
+atomic charges are determined by using resonant x-ray scattering experiments
+further analyzed with the help of ab initio calculations of the corresponding
+scattering factors. We have found that this reorganization concerns only a
+small fraction of electron and is necessary to reconcile all the experimental
+data.",0301377v1
+2003-03-02,AFM local oxidation nanopatterning of a high mobility shallow 2D hole gas,"Recently developed AFM local anodic oxidation (LAO) technique offers a
+convenient way of patterning nanodevices, but imposes even more stringent
+requirements on the underlying quantum well structure. We developed a new very
+shallow quantum well design which allows the depth and density of the 2D gas to
+be independently controlled during the growth. A high mobility (0.5 10^6
+cm^2/Vs at 4.2 K) 2D hole gas just 350A below the surface is demonstrated. A
+quantum point contact, fabricated by AFM LAO nanopatterning from this wafer,
+shows 9 quantum steps at 50 mK.",0303011v1
+2003-06-06,Structural evidence against current-induced destruction of charge-ordering in manganese oxides,"High-resolution x-ray scattering, in the presence of an applied current, has
+been used for studying the stability of the charge ordered phase of manganese
+oxides upon current biasing. We find that the charge ordered structure is
+unchanged when a current is flowing in the sample. Such a result indicates that
+the non-linear conduction observed in charge ordered manganites can not be
+ascribed to a current-induced destabilisation of charge ordering.",0306160v1
+2003-09-18,Order-Disorder Transitions and Melting in a Helical Polymer Crystal: Molecular Dynamics Calculations of Poly(Ethylene Oxide),"Structural transitions and the melting behavior of crystalline poly(ethylene
+oxide),(CH2-CH2-O)n, (PEO) has been investigated using fully atomistic,
+constant pressure-constant temperature (NPT) molecular dynamics (MD)
+simulations. Melting of PEO proceeds in two stages; Order parameters reveal the
+loss of interchain orientational correlations and of chain helicity in the
+first and second stages of melting respectively. Sliding diffusion and
+anisotropic reorientational dynamics of the polymer backbone are observed in
+the solid state, in agreement with 1H NMR experiments.",0309431v1
+2003-12-09,The oxygen isotope effect on critical temperature in superconducting copper oxides,"The isotope effect provided a crucial key to the development of the BCS
+(Bardeen-Cooper-Schrieffer) microscopic theory of superconductivity for
+conventional superconductors. In superconducting cooper oxides (cuprates)
+showing an unconventional type of superconductivity, the oxygen isotope effect
+is very peculiar: the exponential coefficient strongly depends on doping level.
+No consensus has been reached so far on the origin of the isotope effect in the
+cuprates. Here we show that the oxygen isotope effect in cuprates is in
+agreement with the bisoliton theory of superconductivity.",0312229v2
+2003-12-23,Electron localization in pure and defective ceria by a unified LDA+U approach,"The electronic and structural properties of pure and defective cerium oxide
+are investigated using a unified LDA+U approach which allows to treat the
+different valence states of Ce occurring for different stoichiometries on a
+same ground, without any {\it a priori} assumptions on the defect chemistry.
+The method correctly predicts the atomistic and electronic structures of the
+\4ce and \3ce bulk phases, as well as the subtle defect chemistry in reduced
+materials \xce, which controls the oxygen storage functionality of cerium-based
+oxides. The analysis of the energetics highlights the limits of the LDA+U
+method and possible extensions are proposed.",0312601v1
+2003-12-29,La0.95Sr0.05CoO3: An efficient room-temperature thermoelectric oxide,"We present measurements of electrical resistivity, thermal conductivity and
+thermopower of polycrystalline Sr-doped LaCoO3 with composition
+La0.95Sr0.05CoO3. Our data show that the investigated compound exhibits a very
+respectable room temperature thermoelectric figure of merit value of 0.18. Our
+results not only show that oxides are promising candidates for thermoelectric
+cooling applications, but also point towards the need for careful theoretical
+calculations that will serve as a guide in producing the next generation of
+thermoelectric materials.",0312670v1
+2004-02-02,Universal charge transport of the Mn oxides in the high temperature limit,"We have found that various Mn oxides have the universal resistivity and
+thermopower in the high temperature limit. The resistivities and thermopowers
+of all the samples go toward constant values of 7$\pm$1 m$\Omega$cm and
+$-79\pm$3 $\mu$V/K, which are independent of carrier density and crystal
+structures. We propose that the electric conduction occurs in a highly
+localized way in the high temperature limit, where the exchange of entropy and
+charge occurs in the neighboring Mn$^{3+}$ and Mn$^{4+}$ ions.",0402032v1
+2004-02-09,Electronic structure and light-induced conductivity in a transparent refractory oxide,"Combined first-principles and experimental investigations reveal the
+underlying mechanism responsible for a drastic change of the conductivity (by
+10 orders of magnitude) following hydrogen annealing and UV-irradiation in a
+transparent oxide, 12CaO.7Al2O3, found by Hayashi et al. The charge transport
+associated with photo-excitation of an electron from H, occurs by electron
+hopping. We identify the atoms participating in the hops, determine the exact
+paths for the carrier migration, estimate the temperature behavior of the
+hopping transport and predict a way to enhance the conductivity by specific
+doping.",0402218v1
+2004-04-10,Thermal conductivity of the thermoelectric layered cobalt oxides measured by the Harman method,"In-plane thermal conductivity of the thermoelectric layered cobalt oxides has
+been measured using the Harman method, in which thermal conductivity is
+obtained from temperature gradient induced by applied current. We have found
+that the charge reservoir block (the block other than the CoO$_2$ block)
+dominates the thermal conduction, where a nano-block integration concept is
+effective for material design. We have further found that the thermal
+conductivity shows a small but finite in-plane anisotropy between $a$ and $b$
+axes, which can be ascribed to the misfit structure.",0404248v1
+2004-06-10,Production of Gas Phase Zinc Oxide Nanoclusters by Pulsed Laser Ablation,"We present experimental results on the photoluminescence (PL) of
+gas-suspended zinc oxide nanoclusters prepared during ablation of sintered ZnO
+targets by a pulsed ArF laser in the presence of oxygen ambient gas. The PL
+spectra in the UV spectral region correspond to the exciton recombination in
+the nanoclusters which are crystallized and cooled down to the temperature of
+the ambient gas in the ablation chamber. The time evolution of the spectra as
+well as their dependence on the ambient gas pressure are discussed.",0406251v1
+2004-09-10,Non-generality of the Kadowaki-Woods ratio in correlated oxides,"An explicit expression for the Kadowaki-Woods ratio in correlated metals is
+derived by invoking saturation of the (high-frequency) Fermi-liquid scattering
+rate at the Mott-Ioffe-Regel limit. Significant deviations observed in a number
+of oxides are quantitatively explained due to variations in carrier density,
+dimensionality, unit cell volume and the number of individual sheets in the
+Brillouin zone. A generic re-scaling of the original Kadowaki-Woods plot is
+also presented.",0409252v1
+2004-09-30,"Comment on Phys. Stat. Sol. (b) 236 (2003) 281 paper by A. M. Oles ""Orbital ordering and orbital fluctuations in transition metal oxides""","We argue that the 3A2 state considered by Oles in Phys. Stat. Sol. (b) 236
+(2003) 281 for the d2 system occurring in the V3+ ion in V2O3 and LaVO3 as well
+as in Ti2+ ion in TiO and in many other oxides is wrong. The proper ground
+state is 3T1g - its 9-fold degeneracy is further split in a crystal by
+intra-atomic spin-orbit interactions and lattice distortions.",0409777v1
+2004-11-10,Quantum Monte Carlo study of MnO solid,"Electronic structure of the manganese oxide solid is studied by the quantum
+Monte Carlo (QMC) methods. The trial wavefunctions are built using orbitals
+from unrestricted Hartree-Fock and Density Functional Theory, and the
+electron-electron correlation is recovered by the fixed-node QMC. The
+correlation effects are significant and QMC estimations of the gap and cohesion
+show a very good agreement with experiment. Comparison with hybrid functional
+results points out the importance of the exact exchange for improvement of the
+Density Functional description of transition metal oxide systems.",0411247v2
+2005-01-07,Achieving fast oxygen diffusion in perovskites by cation ordering,"The oxygen-exchange behavior has been studied in half-doped manganese and
+cobalt perovskite oxides. We have found that the oxygen diffusivity in
+Gd_{0.5}Ba_{0.5}MnO_{3-\delta} can be enhanced by orders of magnitude by
+inducing crystallographic ordering among lanthanide and alkali-earth ions in
+the A-site sublattice. Transformation of a simple cubic perovskite, with
+randomly occupied A-sites, into a layered crystal GdBaMn_2O_{5+x} (or
+isostructural GdBaCo_2O_{5+x} for cobalt oxide) with alternating lanthanide and
+alkali-earth planes reduces the oxygen bonding strength and provides
+disorder-free channels for ion motion, pointing to an efficient way to design
+new ionic conductors.",0501127v1
+2005-02-10,Electronic Structure of Sodium Cobalt Oxide: Comparing Mono- and Bilayer-hydrate,"To shed new light on the mechanism of superconductivity in sodium cobalt
+oxide bilayer-hydrate (BLH), we perform a density functional calculation with
+full structure optimization for BLH and its related nonsuperconducting phase,
+monolayer hydrate (MLH). We find that these hydrates have similar band
+structures, but a notable difference can be seen in the $a_{1g}$ band around
+the Fermi level. While its dispersion in the $z$ direction is negligibly small
+for BLH, it is of the order of 0.1 eV for MLH. This result implies that the
+three dimensional feature of the $a_{1g}$ band may be the origin for the
+absence of superconductivity in MLH.",0502256v1
+2005-03-19,Tunneling spectroscopy studies of aluminum oxide tunnel barrier layers,"We report scanning tunneling microscopy and ballistic electron emission
+microscopy studies of the electronic states of the uncovered and
+chemisorbed-oxygen covered surface of AlOx tunnel barrier layers. These states
+change when chemisorbed oxygen ions are moved into the oxide by either flood
+gun electron bombardment or by thermal annealing. The former, if sufficiently
+energetic, results in locally well defined conduction band onsets at ~1 V,
+while the latter results in a progressively higher local conduction band onset,
+exceeding 2.3 V for 500 and 600 C thermal anneals.",0503495v1
+2005-04-08,Production of Indium Doped Zinc Oxide Thin Films by Pulsed Laser Ablation,"An original modification of the standard Pulse Laser Deposition (PLD) method
+for preparing both undoped and indium doped zinc oxide (ZnO:In) thin films at
+low substrate temperature is proposed. This preparation method does not demand
+any further post-deposition annealing treatment of the grown films. The
+developed method allows to grow thin films at low substrate temperature that
+prevents them from the considerable loss of their intrinsic electrical and
+optical properties. The influence of deposition parameters on the electrical
+and optical parameters of the undoped and the indium doped ZnO thin films is
+also analysed.",0504200v1
+2005-04-14,High Throughput Oxide Lattice Engineering by Parallel Laser Molecular Beam Epitaxy and Concurrent X-ray Diffraction,"A novel laser molecular beam epitaxy (LMBE) system for the fabrication of
+atomically controlled oxides superlattices and an x-ray diffractometer that
+measures spatially-resolved x-ray diffraction spectra have been developed based
+on the concept of combinatorial methodology. The LMBE chamber has two moving
+masks, an automated target stage, a substrate heating laser, and an in-situ
+scanning reflection high-energy electron diffraction system. The x-ray
+diffractometer with a curved monochromator and two-dimensional detector is used
+for rapid concurrent x-ray diffraction intensity mapping with the two axes of
+the detector corresponding to the diffraction angle and a position in the
+sample.",0504352v1
+2005-04-19,"Evidence against strong correlation in 4d transition metal oxides, CaRuO3 and SrRuO3","We investigate the electronic structure of 4d transition metal oxides, CaRuO3
+and SrRuO3. The analysis of the photoemission spectra reveals significantly
+weak electron correlation strength (U/W ~ 0.2) as expected in 4d systems and
+resolves the long standing issue that arose due to the prediction of large U/W
+similar to 3d-systems. It is shown that the bulk spectra, thermodynamic
+parameters and optical properties in these systems can consistently be
+described using first principle approaches. The observation of different
+surface and bulk electronic structures in these weakly correlated 4d systems is
+unusual.",0504466v1
+2005-05-03,Ferroelectricity in ultra-thin perovskite films,"We report studies of ferroelectricity in ultra-thin perovskite films with
+realistic electrodes. The results reveal stable ferroelectric states in thin
+films less than 10 \AA thick with polarization normal to the surface. Under
+short-circuit boundary conditions, the screening effect of realistic electrodes
+and the influence of real metal/oxide interfaces on thin film polarization are
+investigated. Our studies indicate that metallic screening from the electrodes
+is affected by the difference in work functions at oxide surfaces. We
+demonstrate this effect in ferroelectric PbTiO$_3$ and BaTiO$_3$ films.",0505051v1
+2005-05-08,Orbital Disordering and metal-insulator transition with hole-doping in perovskite-type vanadium oxides,"Filling-control metal-insulator transitions (MITs) and related electronic
+phase diagrams have been investigated for hole-doped vanadium oxides,
+Pr_{1-x}Ca_xVO_3, Nd_{1-x}Sr_xVO_3 and Y_{1-x}Ca_xVO_3, with perovskite
+structure. The increase of the doping level x causes the melting of the G-type
+(and C-type) orbital order, prior to or concomitantly with the MIT, due partly
+to the doped-hole motion and partly to the ramdom potential arising from the
+quenched disorder. In particular, the G-type spin- and C-type orbital-ordered
+phase present in Y_{1-x}Ca_xVO_3 disappears immediately upon hole doping,
+around x=0.02. On the other hand, the critical doping level x for MIT is
+governed by the electron-correlation strength of the undoped parent compound.",0505190v1
+2005-05-13,Quantitative Analysis of Photo-Thermal Stability of CdSe/CdS Core-Shell Nanocrystals,"We report here investigations on the instability in luminescence of bare
+(TOPO-stabilized) and CdS- capped CdSe particles under infrared radiation.
+During photo-thermal annealing the formation of oxide layers on the surfaces of
+the particles create defect states. Consequently there is a reduction in
+particle size. These two effects control the light output from the samples. We
+make a quantitative comparison of the stability of bare CdSe and core-shell
+type CdSe-CdS particles under photo-annealing. Using diffusion theory, we show
+that the volume of the oxide layer, adhered to the crystallites, play a
+dominant role in controlling the luminosity of the particles.",0505342v1
+2005-06-29,First-principles study of epitaxial strain in perovskites,"Using an extension of a first-principles method developed by King-Smith and
+Vanderbilt [Phys. Rev. B {\bf 49}, 5828 (1994)], we investigate the effects of
+in-plane epitaxial strain on the ground-state structure and polarization of
+eight perovskite oxides: BaTiO$_3$, SrTiO$_3$, CaTiO$_3$, KNbO$_3$, NaNbO$_3$,
+PbTiO$_3$, PbZrO$_3$, and BaZrO$_3$. In addition, we investigate the effects of
+a nonzero normal stress. The results are shown to be useful in predicting the
+structure and polarization of perovskite oxide thin films and superlattices.",0506777v1
+2005-08-29,Spin-Phonon Coupling in High-T_c Copper Oxides,"Band calculations on HgBa$_2$CuO$_4$ and La$_{(2-x)}$Sr$_x$CuO$_4$ with
+phonon and spin-waves within the CuO planes show that partial gaps are created
+at various energies depending on wavelengths. Spin and phonon gaps appear at
+different energies when the modulations are along [1,1,0], while they are at
+the same energy for modulations along [1,0,0].
+  It is shown that the ability to form gaps and antiferromagnetic waves is
+correlated with the strength of the interaction parameter $\lambda_{sf}$ for
+spin fluctuations. Many unusual properties of the high-T$_C$ oxides can be
+understood from spin-phonon coupling.",0508672v1
+2005-09-21,Nearly free electrons in the layered oxide superconductor Ag5Pb2O6,"We present first measurements of quantum oscillations in the layered oxide
+superconductor
+  Ag5Pb2O6. From a detailed angular and temperature dependent study of the dHvA
+effect we determine the electronic structure and demonstrate that the electron
+masses are very light, m^* is approximately equalt to 1.2 m_e. The Fermi
+surface we observe is essentially that expected of nearly-free electrons -
+establishing
+  Ag5Pb2O6 as the first known example of a monovalent, nearly-free electron
+superconductor at ambient pressure.",0509547v1
+2006-01-24,Electric-field-dependent spectroscopy of charge motion using a single-electron transistor,"We present observations of background charge fluctuators near an Al-AlO_x-Al
+single-electron transistor on an oxidized Si substrate. The transistor design
+incorporates a heavily doped substrate and top gate, which allow for
+independent control of the substrate and transistor island potentials. Through
+controlled charging of the Si/SiO_2 interface we show that the fluctuators
+cannot reside in the Si layer or in the tunnel barriers. Combined with the
+large measured signal amplitude, this implies that the defects must be located
+very near the oxide surface.",0601553v2
+2006-03-19,Electronic properties of silica nanowires,"Thin nanowires of silicon oxide were studied by pseudopotential density
+functional electronic structure calculations using the generalized gradient
+approximation. Infinite linear and zigzag Si-O chains were investigated. A wire
+composed of three-dimensional periodically repeated Si4O8 units was also
+optimized, but this structure was found to be of limited stability. The
+geometry, electronic structure, and Hirshfeld charges of these silicon oxide
+nanowires were computed. The results show that the Si-O chain is metallic,
+whereas the zigzag chain and the Si4O8 nanowire are insulators.",0603485v1
+2006-03-23,Interface controlled electronic charge inhomogeneities in correlated heterostructures,"For heterostructures of ultrathin, strongly correlated copper-oxide films and
+dielectric perovskite layers, we predict inhomogeneous electronic interface
+states. Our study is based on an extended Hubbard model for the cuprate film.
+The interface is implemented by a coupling to the electron and phonon degrees
+of freedom of the dielectric oxide layer. We find that electronic ordering in
+the film is associated with a strongly inhomogeneous polaron effect. We propose
+to consider the interfacial tuning as a powerful mechanism to control the
+charge ordering in correlated electronic systems.",0603629v2
+2006-06-01,Cluster assimilation and collisional filtering on metal-oxide surfaces,"We present the first ab initio molecular dynamics study of collisions between
+metal-oxide clusters and surfaces. The resulting trajectories reveal that the
+internal degrees of freedom of the cluster play a defining role in collision
+outcome. The phase space of incoming internal temperature and translational
+energy exhibits regions where the collision process itself ensures that each
+cluster which does not rebound from the surface assimilates seamlessly onto it
+upon impact. This filtering may explain recent observations of a ""fast
+smoothing mechanism"" during pulsed laser deposition.",0606014v2
+2006-07-24,The interface between a polar perovskite oxide and silicon from monoatomic lines,"We report a study on the interface between polar high-k materials and the
+Si(001)-(2X1) reconstructed surface with LaAlO3 taken as a prototype material.
+The construction of the interface is based on the prior growth of metal lines
+followed by oxidation, whose stability against oxygen coverage is studied.
+Electronic structure calculations within the Density Functional Theory
+framework help in building the interface and understanding its bonding
+structure. Moreover, we computed a conduction band offset of 1.9 eV, in
+agreement with electronic applications requirement. The results may provide a
+guidance for interface processing.",0607609v2
+2006-08-28,Photoluminescence of nanocrystals embedded in oxide matrices,"We used the theory of finite periodic systems to explain the
+photoluminescence spectra dependence on the average diameter of nanocrystals
+embedded in oxide matrices. Because of the broad matrix band gap, the
+photoluminescence response is basically determined by isolated nanocrystals and
+sequences of a few of them. With this model we were able to reproduce the shape
+and displacement of the experimentally observed photoluminescence spectra.",0608605v3
+2006-09-14,Strain induced pressure effect in pulsed laser deposited thin films of the strongly correlated oxide V2O3,"V2O3 thin films about 10 nm thick were grown on Al2O3 (0001) by pulsed laser
+deposition. The XRD analysis is in agreement with R-3c space group. Some of
+them exhibit the metal / insulator transition characteristic of V2O3 bulk
+material and others samples exhibit a metallic behavior. For the latter, the
+XPS analysis indicates an oxidation state of +III for vanadium. There is no
+metal / insulator transition around 150 K in this sample and a strongly
+correlated Fermi liquid rho = AT2 behavior of the resistivity at low
+temperature is observed, with a value of A of 1.2 10-4 ohm cm, 3 times larger
+than the bulk value at 25 kbar.",0609342v1
+2006-12-06,Configurational electronic entropy and the phase diagram of mixed-valence oxides: the case of Li$_x$FePO$_4$,"We demonstrate that configurational electronic entropy, previously neglected,
+in {\it ab initio} thermodynamics of materials can qualitatively modify the
+finite-temperature phase stability of mixed-valence oxides. While
+transformations from low-T ordered or immiscible states are almost always
+driven by configurational disorder (i.e. random occupation of lattice sites by
+multiple species), in FePO$_4$--LiFePO$_4$ the formation of a solid solution is
+almost entirely driven by electronic, rather than ionic configurational
+entropy. We argue that such an electronic entropic mechanism may be relevant to
+most other mixed-valence systems.",0612163v1
+2006-12-29,Chemical trends of superconducting properties in pyrochlore oxides,"Chemical trends of fundamental superconducting parameters and normal-state
+properties are described for a family of pyrochlore oxide superconductors.
+Particularly, the change of Tc from 1.0 K for alpha-pyrochlore Cd2Re2O7 to 3.3
+K (A = Cs), 6.3 K (Rb), and 9.6 K (K) for beta-pyrochlore AOs2O6 is discussed
+on the basis of the conventional BCS scheme. Enhanced Tc and anomalous features
+observed for KOs2O6 are ascribed to low-energy phonons probably coming from the
+rattling of the K cations.",0612682v1
+2007-01-19,Chemical Liquid Phase Deposition of Thin Aluminum Oxide Films,"Thin aluminum oxide films were deposited by a new and simple physicochemical
+method called chemical liquid phase deposition (CLD) on semiconductor
+materials. Aluminum sulfate with crystallized water and sodium bicarbonate were
+used as precursors for film growth, and the control of the system pH value
+played an important role in this experiment. The growth rate is 12 nm/h at room
+temperature. Post-growth annealing not only densifies and purifies the films,
+but results in film crystallization as well. Excellent quality of Al2O3 films
+in this work is supported by electron dispersion spectroscopy, Fourier
+transform infrared spectrum, X-ray diffraction spectrum and scanning electron
+microscopy photograph.",0701488v1
+2000-01-27,Spiral Turbulence: From the Oxidation of CO on Pt(110) to Ventricular Fibrillation,"We give a brief overview of systems that show spiral patterns and
+spatiotemporally chaotic states. We concentrate on two physical systems: (1)
+the oxidation of CO on Pt(110) and (2) ventricular fibrillation in hearts. The
+equations that have been suggested as simple models for these two different
+systems are closely related for they are both {\it excitable media}. We present
+these equations and give a short summary of the phenomena they yield.}",0001063v1
+2001-11-12,Pattern Formation on the Edge of Chaos: CO Oxidation on Pt(110) under Global Delayed Feedback,"Experiments with catalytic CO oxidation on Pt(110) show that chemical
+turbulence in this system can be suppressed by application of appropriate
+global delayed feedbacks. Different spatiotemporal patterns, seen near a
+transition from turbulence to uniform oscillations, are investigated. Using a
+method based on the Hilbert transform, spatial distributions of local phase and
+amplitude in such patterns are reconstructed from the experimental data. The
+observed phenomena are reproduced in simulations using a theoretical model of
+the reaction.",0111026v1
+2003-10-23,Photoluminescence properties of forsterite (Mg2SiO4) nanobelts synthesized from Mg and SiO2 powders,"Ternary oxide forsterite Mg2SiO4 single-crystalline nanobelts have been
+synthesized at high yields via SiO2 assistant-oxide through a VS process. The
+PL properties of the forsterite Mg2SiO4 nanobelts were observed. The emission
+peak at 625 nm is attributed to the 4T1 - 6A1 transition of the trace Mn2+
+ions. The other emission peak at 400nm may be due to the defects.",0310114v1
+2006-12-06,Electrically addressing a single self-assembled quantum dot,"We report on the use of an aperture in an aluminum oxide layer to restrict
+current injection into a single self-assembled InAs quantum dot, from an
+ensemble of such dots within a large mesa. The insulating aperture is formed
+through the wet-oxidation of a layer of AlAs. Under photoluminescence we
+observe that only one quantum dot in the ensemble exhibits a Stark shift, and
+that the same single dot is visible under electroluminescence. Autocorrelation
+measurements performed on the electroluminescence confirm that we are observing
+emission from a single quantum dot.",0612046v1
+2007-05-05,Evanescent quadrupole polariton,"In the work we demonstrate the formation of new type of polariton on the
+interface between a cuprous oxide slab and a polystyrene micro-sphere placed on
+the slab. The evanescent field of the resonant whispering gallery mode (WGM)
+has a substantial gradient, and therefore effectively couples with the
+quadrupole $1S$ excitons in cuprous oxide. This evanescent polariton has a long
+life-time ($1.7 ns$), which is determined only by its excitonic component. The
+polariton lower branch has a well pronounced minimum. This suggests that this
+excitation can be utilized for BEC. The spatial coherence of the polariton can
+be improved by assembling the micro-spheres in a linear chain.",0705.0749v1
+2007-05-23,XANES determination of chromium oxidation states in glasses: comparison with optical absorption spectroscopy,"The oxidation state of chromium in glasses melted in an air atmosphere with
+and without refining agents was investigated by Cr K-edge X-ray Absorption
+Near-Edge Structure (XANES) and optical absorption spectroscopy. A good
+agreement in the relative proportion of Cr(III) and Cr(VI) is obtained between
+both methods. We show that the chemical dependence of the absorption
+coefficient of Cr(III) is less important in XANES than in optical absorption
+spectroscopy. The comparison of glasses melted under different conditions
+provides an indirect assessment of the molar extinction coefficient of Cr(VI)
+in glasses.",0705.3355v1
+2007-06-12,High-quality all-oxide Schottky junctions fabricated on heavily Nb-doped SrTiO3 substrates,"We present a detailed investigation of the electrical properties of epitaxial
+La0.7Sr0.3MnO3/SrTi0.98Nb0.02O3 Schottky junctions. A fabrication process that
+allows reduction of the junction dimensions to current electronic device size
+has been employed. A heavily doped semiconductor has been used as a substrate
+in order to suppress its series resistance. We show that, unlike standard
+semiconductors, high-quality oxide-based Schottky junctions maintain a highly
+rectifying behavior for doping concentration of the semiconductor larger than
+10^20 cm^(-3). Moreover, the junctions show hysteretic current-voltage
+characteristics.",0706.1620v2
+2007-06-20,Conformal oxide coating of Carbon Nanotubes,"The International Roadmap for Ferroelectric Memories requires
+three-dimensional integration of high-dielectric materials onto metal
+interconnects or bottom electrodes by 2010. We report the first integration of
+high-dielectric oxide films onto carbon nanotube electrodes with an aim of
+ultra-high integration density of FeRAMs (Tb/in2).",0706.2998v1
+2007-06-21,Self-interaction correction with Wannier functions,"We describe the behavior of the Perdew-Zunger self-interaction-corrected
+local density approximation (SIC-LDA) functional when implemented in a
+plane-wave pseudopotential formalism with Wannier functions. Prototypical
+semiconductors and wide-bandgap oxides show a large overcorrection of the LDA
+bandgap. Application to transition-metal oxides and elements with d electrons
+is hindered by a serious breaking of the spherical symmetry, which appears even
+in a closed shell free atom. Our results indicate that, when all spherical
+approximations are lifted, the general applicability of orbital-dependent
+potentials is very limited and should be reconsidered in favor of rotationally
+invariant functionals.",0706.3210v1
+2007-07-12,Properties of high-T$_C$ copper oxides from the nearly-free electron model,"The generic band structure of high-T$_C$ copper oxides is simulated by the
+nearly free-electron model (NFE) in two dimensions (2-D) with parameters from
+band calculations. Interaction between phonons and spin waves will cause
+potential modulations and pseudogaps, and the strength of the modulations, the
+wave lengths and the doping, are all related. A Fermi-surface ""arc"" is found
+for dynamic spin/phonon waves. The confinement of superconductivity between two
+limiting dopings can be a result of competition with the pseudogap at low
+doping and weak coupling at high doping.",0707.1804v1
+2007-07-20,A mechanism for unipolar resistance switching in oxide non-volatile memory devices,"Building on a recently introduced model for non-volatile resistive switching,
+we propose a mechanism for unipolar resistance switching in
+metal-insulator-metal sandwich structures. The commutation from the high to low
+resistance state and back can be achieved with successive voltage sweeps of the
+same polarity. Electronic correlation effects at the metal-insulator interface
+are found to play a key role to produce a resistive commutation effect in
+qualitative agreement with recent experimental reports on binary transition
+metal oxide based sandwich structures.",0707.3077v1
+2007-08-02,Reduction of the Casimir force using aerogels,"By using silicon oxide based aerogels we show numerically that the Casimir
+force can be reduced several orders of magnitude, making its effect negligible
+in nanodevices. This decrease in the Casimir force is also present even when
+the aerogels are deposited on metallic substrates. To calculate the Casimir
+force we model the dielectric function of silicon oxide aerogels using an
+effective medium dielectric function such as the Clausius-Mossotti
+approximation. The results show that both the porosity of the aerogel and its
+thickness can be use as control parameters to reduce the magnitude of the
+Casimir force.",0708.0434v1
+2007-08-14,Nimesulide limits kainate-induced oxidative damage in the rat hippocampus,"Kainate induces a marked expression of cyclooxygenase-2 after its systemic
+administration. Because cyclooxygenase-2 activity is associated to the
+production of reactive oxygen species, we investigated the effects of
+nimesulide, a selective cyclooxygenase-2 inhibitor, on kainate-induced in vivo
+oxidative damage in the rat hippocampus. A clinically relevant dose of
+nimesulide (6 mg/kg, i.p.) was administered three times following kainate
+application (9 mg/kg, i.p.). After 24 h of kainate administration, the drastic
+decrease in hippocampal glutathione content and the significant increase in
+lipid peroxidation were attenuated in nimesulide-treated rats, suggesting that
+the induction of cyclooxygenase-2 is involved in kainate-mediated free radicals
+formation.",0708.1971v1
+2007-09-13,Oxide-apertured microcavity single-photon emitting diode,"We have developed a microcavity single-photon source based on a single
+quantum dot within a planar cavity in which wet-oxidation of a high-aluminium
+content layer provides lateral confinement of both the photonic mode and the
+injection current. Lateral confinement of the optical mode in optically pumped
+structures produces a strong enhancement of the radiative decay rate. Using
+microcavity structures with doped contact layers, we demonstrate a
+single-photon emitting diode where current may be injected into a single dot.",0709.2105v1
+2007-10-03,Calculated Momentum Dependence of Zhang-Rice States in Transition Metal Oxides,"Using a combination of local density functional theory and cluster exact
+diagonalization based dynamical mean field theory, we calculate many body
+electronic structures of several Mott insulating oxides including undoped high
+T_{c} materials. The dispersions of the lowest occupied electronic states are
+associated with the Zhang-Rice singlets in cuprates and with doublets,
+triplets, quadruplets and quintets in more general cases. Our results agree
+with angle resolved photoemission experiments including the decrease of the
+spectral weight of the Zhang--Rice band as it approaches k=0.",0710.0678v4
+2007-10-11,Enhancement of surface activity in CO oxidation on Pt(110) through spatiotemporal laser actuation,"We explore the effect of spatiotemporally varying substrate temperature
+profiles on the dynamics and resulting reaction rate enhancement for the
+catalytic oxidation of CO on Pt(110). The catalytic surface is ""addressed"" by a
+focused laser beam whose motion is computer-controlled. The averaged reaction
+rate is observed to undergo a characteristic maximum as a function of the speed
+of this moving laser spot. Experiments as well as modelling are used to explore
+and rationalize the existence of such an optimal laser speed.",0710.2161v1
+2007-11-06,Surface Effects on Oxide Heterostructures,"We report on surface effects on the electronic properties of interfaces in
+epitaxial LaAlO$_3$/SrTiO$_3$ heterostructures. Our results are based on
+first-principles electronic structure calculations for well-relaxed multilayer
+configurations, terminated by an ultrathin LaAlO$_3$ surface layer. On varying
+the thickness of this layer, we find that the interface conduction states are
+subject to almost rigid band shifts due to a modified Fermi energy. Confirming
+experimental data, the electronic properties of heterointerfaces therefore can
+be tuned systematically by alterating the surface-interface distance. We expect
+that this mechanism is very general and applies to most oxide heterostructures.",0711.0813v1
+2007-11-15,Effect of surface nanostructure on temperature programmed reaction spectroscopy: First-principles kinetic Monte Carlo simulations of CO oxidation at RuO2(110),"Using the catalytic CO oxidation at RuO2(110) as a showcase, we employ
+first-principles kinetic Monte Carlo simulations to illustrate the intricate
+effects on temperature programmed reaction spectroscopy data brought about by
+the mere correlations between the locations of the active sites at a
+nanostructured surface. Even in the absence of lateral interactions, this
+nanostructure alone can cause inhomogeneities that cannot be grasped by
+prevalent mean-field data analysis procedures, which thus lead to wrong
+conclusions on the reactivity of the different surface species.",0711.2493v1
+2007-11-27,First-principles study of ferroelectric oxide epitaxial thin films and superlattices: role of the mechanical and electrical boundary conditions,"In this review, we propose a summary of the most recent advances in the
+first-principles study of ferroelectric oxide epitaxial thin films and
+multilayers. We discuss in detail the key roles of mechanical and electrical
+boundary conditions, providing to the reader the basic background for a simple
+and intuitive understanding of the evolution of the ferroelectric properties in
+many nanostructures. Going further we also highlight promising new avenues and
+future challenges within this exciting field or researches.",0711.4201v1
+2007-12-11,Thermoelectric properties of LaRh$_{1-x}$Ni$_x$O$_3$,"We report measurements and analyses of resistivity, thermopower, and thermal
+conductivity of polycrystalline samples of perovskite LaRh$_{1-x}$Ni$_x$O$_3$.
+The thermopower is found to be large at 800 K (185 $\mu$V/K for $x=$0.3), which
+is ascribed to the high-temperature stability of the low-spin state of
+Rh$^{3+}$/Rh$^{4+}$ ions. This clearly contrasts with the thermopower of the
+isostructural oxide LaCoO$_3$, which rapidly decreases above 500 K owing to the
+spin-state transition. The spin state of the transition-metal ions is one of
+the most important parameters in oxide thermoelectrics.",0712.1626v2
+2008-02-15,Quantitative analysis of electronic transport through weakly-coupled metal/organic interfaces,"Using single-crystal transistors, we have performed a systematic experimental
+study of electronic transport through oxidized copper/rubrene interfaces as a
+function of temperature and bias. We find that the measurements can be
+reproduced quantitatively in terms of the thermionic emission theory for
+Schottky diodes, if the effect of the bias-induced barrier lowering is
+included. Our analysis emphasizes the role of the coupling between metal and
+molecules, which in our devices is weak due to the presence of an oxide layer
+at the surface of the copper electrodes.",0802.2153v1
+2008-03-04,Conservation of dielectric constant upon amorphization in perovskite oxides,"We report calculations indicating that amorphous RAO$_3$ oxides, with R and A
+trivalent cations, have approximately the same static dielectric constant as
+their perovskite crystal phase. The effect is due to the disorder-activated
+polar response of non-polar crystal modes at low frequency, which compensates a
+moderate but appreciable reduction of the ionic dynamical charges. The
+dielectric response was studied via density-functional perturbation theory.
+Amorphous samples were generated by molecular dynamics melt-and-quench
+simulations.",0803.0478v1
+2008-05-15,Growth of Oxide Compounds under Dynamic Atmosphere Composition,"Commercially available gases contain residual impurities leading to a
+background oxygen partial pressure of typically several 10^{-6} bar,
+independent of temperature. This oxygen partial pressure is inappropriate for
+the growth of some single crystals where the desired oxidation state possesses
+a narrow stability field. Equilibrium thermodynamic calculations allow the
+determination of dynamic atmosphere compositions yielding such self adjusting
+and temperature dependent oxygen partial pressures, that crystals like ZnO,
+Ga2O3, or Fe{1-x}O can be grown from the melt.",0805.2217v1
+2008-05-23,Atomic Layer Deposition of Metal Oxides on Pristine and Functionalized Graphene,"We investigate Atomic Layer Deposition (ALD) of metal oxide on pristine and
+functionalized graphene. On pristine graphene, ALD coating can only actively
+grow on edges and defect sites, where dangling bonds or surface groups react
+with ALD precursors. This affords a simple method to decorate and probe single
+defect sites in graphene planes. We used perylene tetracarboxylic acid (PTCA)
+to functionalize graphene surface and selectively introduced densely packed
+surface groups on graphene. Uniform ultrathin ALD coating on PTCA graphene was
+achieved over large area. The functionalization method could be used to
+integrate ultrathin high-k dielectrics in future graphene electronics.",0805.3712v1
+2008-08-08,New Insight into the Properties of Proton Conducting Oxides from Neutron Total Scattering,"In this paper we investigated the most important family of proton conducting
+oxides, i.e. cerates, by means of pair distribution function analysis (PDF)
+obtained from total neutron scattering data. The results clearly demonstrates
+that the local structure plays a fundamental role in the protonation process.
+Oxygen vacancy creation by acceptor doping reduces the local structure symmetry
+which is then restored upon water uptake. This mechanism mainly involves the
+Ba-O shell which flexibility seems to be at the basis of the proton conduction
+mechanism, thus providing a direct insight on the design of optimal proton
+conducting materials.",0808.1162v1
+2008-09-08,Quantum spin Hall effect in a transition metal oxide Na2IrO3,"We study theoretically the electronic states in a $5d$ transition metal oxide
+Na$_2$IrO$_3$, in which both the spin-orbit interaction and the electron
+correlation play crucial roles. Tight-binding model analysis together with the
+fisrt-principles band structure calculation predicts that this material is a
+layered quantum spin Hall system. Due to the electron correlation, an
+antiferromagnetic order first develops at the edge, and later inside the bulk
+at low temperatures.",0809.1317v2
+2008-09-18,Band Offsets at Semiconductor-Oxide Interfaces from Hybrid Density Functional Calculations,"Band offsets at semiconductor-oxide interfaces are determined through a
+scheme based on hybrid density functionals, which incorporate a fraction
+$\alpha$ of Hartree-Fock exchange. For each bulk component, the fraction
+$\alpha$ is tuned to reproduce the experimental band gap, and the conduction
+and valence band edges are then located with respect to a reference level. The
+lineup of the bulk reference levels is determined through an interface
+calculation, and shown to be almost independent of the fraction $\alpha$.
+Application of this scheme to the Si-SiO$_2$, SiC-SiO$_2$, and Si-HfO$_2$
+interfaces yields excellent agreement with experiment.",0809.3119v1
+2008-12-04,Impurity-induced frustration in correlated oxides,"Using the example of Zn-doped La2CuO4, we demonstrate that a spinless
+impurity doped into a non-frustrated antiferromagnet can induce substantial
+frustrating interactions among the spins surrounding it. This counterintuitive
+result is the key to resolving discrepancies between experimental data and
+earlier theories. Analytic and quantum Monte Carlo studies of the
+impurity-induced frustration are in a close accord with each other and
+experiments. The mechanism proposed here should be common to other correlated
+oxides as well.",0812.1023v3
+2008-12-26,Germanium Segregation in CVD Grown Sige Layers for Flash Memory Application,"A 2D layer of spherical, crystalline Ge nanodots embedded in SiO2 was formed
+by low pressure chemical vapour deposition combined with furnace oxidation and
+rapid thermal annealing. The samples were characterized structurally by using
+transmission electron microscopy and rutherford back scattering spectrometry,
+as well as electrically by measuring CV and IV characteristics. It was found
+that formation of a high density Ge dots took place due to oxidation induced Ge
+segregation. The dots are situated in the SiO2 on the average distance 5 nm
+from the substrate. Strong evidence of charge storage effect in the crystalline
+Ge nanodot layer is demonstrated by the hysteresis behavior of the high
+frequency CV curves.",0812.4680v1
+2009-01-28,Mechanism of orbital reconstruction at the interfaces of transition metal oxides,"Orbital reconstruction at interfaces between YBa2Cu3O6 and SrO-terminated
+SrTiO3 is studied using local spin density approximation (LSDA) with
+intra-atomic Coulomb repulsion (LSDA+U). The change of population of
+interfacial Cu 3d orbitals results in stabilization of a new oxidation state
+$3d^8$ which involves an additional modification of orbital occupancies in the
+nearest SrO and TiO2 layers. We find that an increase of electron charge in Cu
+3d_{x^2-y^2} states counterbalances a depopulation of 3d_{3z^2-r^2} orbitals
+which induces, on account of the onsite Coulomb repulsion U, a splitting of
+3d_{3z^2-r^2} states at CuO2-SrO interfaces.",0901.4406v2
+2009-01-29,Self-Doping Induced Orbital-Selective Mott Transition in Hg2Ru2O7,"Pyrochlore oxides are fascinating systems where strong, multi-orbital
+correlations in concert with geometrical frustration give rise to unanticipated
+physical properties. The detailed mechanism of the insulator-metal transitions
+(IMT) underpinning these phenomena is, however, ill-understood in general.
+Motivated thereby, we study the IMT in the pyrochlore ${\rm Hg_{2}Ru_{2}O_{7}}$
+using LDA+DMFT. In contrast to the well-known examples of Mott transitions in
+TMO, we show that, in the negative charge-transfer situation characteristic of
+\hg, self-doping plays a crucial role in the emergence of an orbital-selective
+IMT. We argue that this mechanism has broader relevance to other correlated
+pyrochlore oxides.",0901.4658v1
+2009-02-03,Current-perpendicular-to-plane magnetoresistance of a domain wall confined in a nano-oxide-layer,"We theoretically study the current-perpendicular-to-plane magnetoresistance
+of a domain wall confined in a current-confined-path (CCP) structure made of a
+nano-oxide-layer (NOL). In order to calculate the MR ratio of the system, the
+continuity equations for charge and spin currents are numerically solved with
+the three-dimensional CCP geometry by use of finite element method. It is
+confirmed that the MR ratio is enhanced by the CCP structure, which is
+consistent with the experimental results.",0902.0644v1
+2009-02-16,Sensor/ROIC Integration using Oxide Bonding,"We explore the Ziptronix Direct Bond Interconnect technology for the
+integration of sensors and readout integrated circuits (ROICs) for high energy
+physics. The technology utilizes an oxide bond to form a robust mechanical
+connection between layers which serves to assist with the formation of metallic
+interlayer connections. We report on testing results of sample sensors bonded
+to ROICs and thinned to 100 microns.",0902.2801v1
+2009-02-18,Effects of external global noise on the catalytic CO oxidation on Pt(110),"Oxidation reaction of CO on a single platinum crystal is a reaction-diffusion
+system that may exhibit bistable, excitable, and oscillatory behavior. We
+studied the effect of a stochastic signal artificially introduced into the
+system through the partial pressure of CO. First, the external signal is
+employed as a turbulence suppression tool, and second, it modifies the
+boundaries in the bistable transition between the CO and oxygen covered phases.
+Experiments using photoemission electron microscopy (PEEM) together with
+numerical simulations performed with the Krischer-Eiswirth-Ertl (KEE) model are
+presented.",0902.3162v1
+2009-02-20,Properties of high-$T_c$ copper oxides from band models of spin-phonon coupling,"The mechanism of spin-phonon coupling (SPC) and possible consequencies for
+the properties of high-$T_C$ copper oxides are presented. The results are based
+on ab-initio LMTO band calculations and a nearly free-electron (NFE) model of
+the band near $E_F$. Many observed properties are compatible with SPC, as for
+the relation between doping and $\vec{q}$ for spin excitations and their energy
+dependence. The main pseudogap is caused by SPC and waves along [1,0,0], but it
+is suggested that secondary waves, generated along [1,1,0], contribute to a
+'waterfall' structure. Conditions for optimal $T_C$, and the possiblities for
+spin enhancement at the surface are discussed.",0902.3580v1
+2009-04-07,Réduction de la nuisance olfactive par oxydation photocatalytique,"Heterogeneous photocatalysis is an interesting alternative for the
+purification, decontamination and smell abatment of air. In the present work,
+the photocatalytic oxidation of 2-butanone (MEK : methyl ethyle ketone) is
+investigated, this low molecular mass product being the source of serious smell
+pollution. The influence of light and of the pollutant concentration were
+investigated in an annular photoreactor. As most VOC's, the degradation rate of
+MEK follows a Langmuir-Hinshelwood type law. Intermediate products were
+analysed by GC-MD ; acetaldehyde is the dominant byproduct of the
+photocatalytic oxidation.",0904.1196v1
+2009-04-14,Stress-driven oxidation chemistry of wet silicon surfaces,"The formation of a hydroxylated native oxide layer on Si(001) under wet
+conditions is studied by means of first principles molecular dynamics
+simulations. Water molecules are found to adsorb and dissociate on the oxidised
+surface leading to rupture of Si-O bonds and producing reactive sites for
+attack by dissolved dioxygen or hydrogen peroxide molecules. Tensile strain is
+found to enhance the driving force for the dissociative adsorption of water,
+suggesting that similar reactions could be responsible for
+environmentally-driven sub-critical crack propagation in silicon.",0904.2091v1
+2009-05-18,Insulator to semi-metal transition in graphene oxide,"Transport properties of progressively reduced graphene oxide (GO) are
+described. Evolution of the electronic properties reveals that as-synthesized
+GO undergoes insulator-semiconductor-semi-metal transitions with reduction. The
+apparent transport gap ranges from 10 ~ 50 meV and approaches zero with
+extensive reduction. Measurements at varying degrees of reduction reveal that
+transport in reduced GO occurs via variable-range hopping and further reduction
+leads to increased number of available hopping sites.",0905.2799v1
+2009-06-05,Evaluation of the optical axis tilt of Zinc oxide films via noncollinear second harmonic generation,"We investigated noncollinear second harmonic generation form Zinc oxide
+films, grown on glass substrates by dual ion beam sputtering technique. At a
+fixed incidence angle, the generated signal is investigated by scanning the
+polarization state of both fundamental beams. We show that the map of the
+generated signal as a function of polarization states of both pump beams,
+together with the analytical curves, allows to retrieve the orientation of the
+optical axis and, eventually, its angular tilt, with respect to the surface
+normal",0906.1156v1
+2009-07-31,New Correlated Model of Colossal Magnetoresistive Manganese Oxides,"A new minimal model is constructed for the doped manganese oxides which
+exhibit colossal magnetoresistance (CMR), involving broad spin-majority
+conduction band as well as nearly localised spin-minority electron states. A
+simple mean field analysis yields a temperature-dependent hybridised band
+structure with suppressed carrier weight at the Fermi level. Spin stiffness is
+complex, indicating unusually strong spin wave damping. Experimental and
+theoretical investigations are needed to further verify the relevance of the
+proposed model.",0907.5512v3
+2009-08-11,Electronic structure of alkaline earth and post-transition metal oxides,"The electronic structure in alkaline earth AeO (Ae = Be, Mg, Ca, Sr, Ba) and
+post-transition metal oxides MeO (Me = Zn, Cd, Hg) is probed with oxygen K-edge
+X-ray absorption and emission spectroscopy. The experimental data is compared
+with density functional theory electronic structure calculations. We use our
+experimental spectra of the oxygen K-edge to estimate the bandgaps of these
+materials, and compare our results to the range of values available in the
+literature.",0908.1581v2
+2009-09-08,Berry-phase theory of polar discontinuities at oxide-oxide interfaces,"In the framework of the modern theory of polarization, we rigorously
+establish the microscopic nature of the electric displacement field D. In
+particular, we show that the longitudinal component of D is preserved at a
+coherent and insulating interface. To motivate and elucidate our derivation, we
+use the example of LAO/STO interfaces and superlattices, where the validity of
+the above conservation law is not immediately obvious. Our results generalize
+the ""locality principle"" of constrained-D density functional theory to the
+first-principles modeling of charge-mismatched systems.",0909.1500v1
+2009-11-11,Transport properties of the layered Rh oxide K_0.49RhO_2,"We report measurements and analyses of resistivity, thermopower and Hall
+coefficient of single-crystalline samples of the layered Rh oxide K_0.49RhO_2.
+The resistivity is proportional to the square of temperature up to 300 K, and
+the thermopower is proportional to temperature up to 140 K. The Hall
+coefficient increases linearly with temperature above 100 K, which is ascribed
+to the triangular network of Rh in this compound. The different transport
+properties between Na_xCoO_2 and K_0.49RhO_2 are discussed on the basis of the
+different band width between Co and Rh evaluated from the magnetotransport.",0911.2156v1
+2009-11-12,Melt Grown ZnO Bulk Crystals,"Bulk crystals of zinc oxide can be grown from the melt by a Bridgman
+technique under pressure. This new technology using an iridium crucible shows
+the potential to yield large single crystals of good crystalline perfection.
+Crystals with diameters up to 33 mm and a length of up to 50 mm have been
+demonstrated. The impurity content can be strongly reduced by using the
+crucibles repeatedly.",0911.2318v1
+2010-01-05,Mechanism for bipolar resistive switching in transition metal oxides,"We introduce a model that accounts for the bipolar resistive switching
+phenomenom observed in transition metal oxides. It qualitatively describes the
+electric field-enhanced migration of oxygen vacancies at the nano-scale. The
+numerical study of the model predicts that strong electric fields develop in
+the highly resistive dielectric-electrode interfaces, leading to a spatially
+inhomogeneous oxygen vacancies distribution and a concomitant resistive
+switching effect. The theoretical results qualitatively reproduce non-trivial
+resistance hysteresis experiments that we also report, providing key validation
+to our model.",1001.0703v1
+2010-01-26,Theory of oxygen K-edge x-ray absorption spectra of cuprates,"The dynamical mean-field theory of the three-band model of copper-oxide
+superconductors is used to calculate the doping dependence of the intensity of
+the oxygen K-edge x-ray absorption spectra of high-$T_c$ copper oxide
+superconductors. The model is found not to reproduce the results of a recent
+experiment, suggesting that at sufficiently high doping the physics beyond the
+conventional three-band model becomes important.",1001.4791v2
+2010-01-30,High yield fabrication of chemically reduced graphene oxide field effect transistors by dielectrophoresis,"We demonstrate high yield fabrication of field effect transistors (FET) using
+chemically reduced graphene oxide (RGO) sheets suspended in water assembled via
+dielectrophoresis. The two terminal resistances of the devices were improved by
+an order of magnitude upon mild annealing at 200 0C in Ar/H2 environment for 1
+hour. With the application of a backgate voltage, all of the devices showed FET
+behavior with maximum hole and electron mobilities of 4.0 and 1.5 cm2/Vs
+respectively. This study shows promise for scaled up fabrication of graphene
+based nanoelectronic devices.",1002.0086v2
+2010-02-02,Effective-mass model of surface scattering in locally oxidized Si nanowires,"We present a simple model to describe the lowest-subbands surface scattering
+in locally oxidized silicon nanowires grown in the [110] direction. To this
+end, we employ an atomistically scaled effective mass model projected from a
+three-dimensional effective mass equation and apply a quantum transport
+formalism to calculate the conductance for typical potential profiles.
+Comparison of our results with hole-transport calculations using atomistic
+models in conjunction with density functional theory (DFT) points to an
+intra-subband scattering mechanism from a potential well.",1002.0435v1
+2010-02-05,A survey of fractured SrTiO$_3$ surfaces: from the micro-meter to nano-meter scale,"Cross-sectional scanning tunneling microscopy was utilized to study fractured
+perovskie oxide surfaces. It was found for the non-cleavable perovskite oxide,
+SrTiO$_{3}$, that atomically flat terraces could be routinely created with a
+controlled fracturing procedure. Optical and scanning electron microscopy as
+well as a profilometer were used to obtain the information from sub-millimeter
+to sub-micrometer scales of the fractured surface topography.",1002.1158v1
+2010-02-17,Position dependent photodetector from large area reduced graphene oxide thin films,"We fabricated large area infrared photodetector devices from thin film of
+chemically reduced graphene oxide (RGO) sheets and studied their photoresponse
+as a function of laser position. We found that the photocurrent either
+increases, decreases or remain almost zero depending upon the position of the
+laser spot with respect to the electrodes. The position sensitive photoresponse
+is explained by Schottky barrier modulation at the RGO film-electrode
+interface. The time response of the photocurrent is dramatically slower than
+single sheet of graphene possibly due to disorder from the chemically synthesis
+and interconnecting sheets.",1002.3191v1
+2010-03-30,Decoupling Graphene from SiC(0001) via Oxidation,"When epitaxial graphene layers are formed on SiC(0001), the first carbon
+layer (known as the ""buffer layer""), while relatively easy to synthesize, does
+not have the desirable electrical properties of graphene. The conductivity is
+poor due to a disruption of the graphene pi-bands by covalent bonding to the
+SiC substrate. Here we show that it is possible to restore the graphene
+pi-bands by inserting a thin oxide layer between the buffer layer and SiC
+substrate using a low temperature, CMOS-compatible process that does not damage
+the graphene layer.",1003.5702v1
+2010-04-01,Interaction of Gold Nanoparticles in Barium Titanate Thin Films,"A novel approach to control the grain size of oxide thin film materials has
+been investigated. Perovskite BaTiO3 shows interesting grain structures when
+deposited on gold predeposited, (111)-oriented, singlecrystal SrTiO3
+substrates. Solid oxide films grow epitaxially on patterned seed layers and
+show variations in grain size relative to the films deposited on SrTiO3
+directly.",1004.0225v1
+2010-04-22,Photoconductance of a submicron oxidized line in surface conductive single crystalline diamond,"We report on sub-bandgap optoelectronic phenomena of hydrogen-terminated
+diamond patterned with a submicron oxidized line. The line acts as an energy
+barrier for the two-dimensional hole gas located below the hydrogenated diamond
+surface. A photoconductive gain of the hole conductivity across the barrier is
+measured for sub-bandgap illumination. The findings are consistent with
+photogenerated electrons being trapped in defect levels within the barrier. We
+discuss the spatial and energetic characteristics of the optoelectronic
+phenomena, as well as possible photocurrent effects.",1004.3900v1
+2010-06-11,Structural Features of Layered Iron Pnictide Oxides (Fe2As2)(Sr4M2O6),"Structural features of newly found perovskite-based iron pnictide oxide
+system have been systematically studied. Compared to REFePnO system,
+perovskite-based system tend to have lower Pn-Fe-Pn angle and higher pnictogen
+height owing to low electronegativity of alkaline earth metal and small
+repulsive force between pnictogen and oxygen atoms. As-Fe-As angles of
+(Fe2As2)(Sr4Cr2O6), (Fe2As2)(Sr4V2O6) and (Fe2Pn2)(Sr4MgTiO6) are close to
+ideal tetrahedron and those pnictogen heights of about 1.40 A are close to
+NdFeAsO with optimized carrier concentration. These structural features of this
+system may leads to realization of high Tc superconductivity.",1006.2351v1
+2010-06-23,Space charge limited conduction with exponential trap distribution in reduced graphene oxide sheets,"We elucidate on the low mobility and charge traps of the chemically reduced
+graphene oxide (RGO) sheets by measuring and analyzing temperature dependent
+current-voltage characteristics. The RGO sheets were assembled between source
+and drain electrodes via dielectrophoresis. At low bias voltage the conduction
+is Ohmic while at high bias voltage and low temperatures the conduction becomes
+space charge limited with an exponential distribution of traps. We estimate an
+average trap density of 1.75x10^16 cm^-3. Quantitative information about charge
+traps will help develop optimization strategies of passivating defects in order
+to fabricate high quality solution processed graphene devices.",1006.4430v1
+2010-08-16,Electronic phase separation in the pyrochlore double-exchange model,"Electronic phase separation and related inhomogeneity is ubiquitously seen in
+strongly-correlated systems. A typical example is found between ferromagnetic
+metal and antiferromagnetic insulator in CMR manganese oxides. Here we
+demonstrate that the geometrical frustration brings distinctive aspects into
+the phase separation phenomena. From Monte Carlo simulation and a simple energy
+comparison for the pyrochlore double-exchange model, we show that such phase
+separation takes place between ferromagnetic and paramagnetic metals. We
+discuss the relevance of our results to a spin-glassy metallic phase found in
+Mo pyrochlore oxides under external pressure.",1008.2786v1
+2010-09-26,Superconductivity above 10 K in Non-Cuprate Oxides,"Beginning in 1973, several non-cuprate transition metal and non-transition
+metal oxides were discovered with superconducting transition temperatures
+between 10 and 30 K. Retrospectives about these discoveries in spinel structure
+LiTi2O4 and perovskite structure (Ba,K)(Bi,Pb)O3 are given.",1009.5134v2
+2010-09-28,Electric field modulation of thermopower for transparent amorphous oxide thin film transistors,"To clarify the electronic density of states (DOS) around the conduction band
+bottom for state of the art transparent amorphous oxide semiconductors (TAOSs),
+InGaZnO4 and In2MgO4, we fabricated TAOS-based transparent thin film
+transistors (TTFTs) and measured their gate voltage dependence of thermopower
+(S). TAOS-based TTFTs exhibit an unusual S behavior. The |S|-value abruptly
+increases, but then gradually decreases as Vg increases, clearly suggesting the
+anti-parabolic shaped DOS is hybridized with the original parabolic shaped DOS
+around the conduction band bottom.",1009.5548v1
+2010-10-20,Templated self-assembly of iron oxide nanoparticles,"We report on self-assembled iron oxide nanoparticle films on silicon
+substrates. In addition to homogeneously assembled layers, we fabricated
+patterned trenches of 40-1000 nm width using electron beam lithography for the
+investigation of assisted self-assembly. The nanoparticles with a diameter of
+20 nm +/- 7% were synthesized by thermal decomposition of iron oleate complexes
+in trioctylamine in presence of oleic acid. Samples with different track widths
+and nanoparticle concentration were characterized by scanning electron
+microscopy and by superconducting quantum interference device magnetometry.",1010.4166v1
+2010-10-20,Phase separation of multicomponent excitonic Bose-Einstein condensates,"For the observation of Bose-Einstein condensation, excitons in cuprous oxide
+are regarded as promising candidates due to their large binding energy and long
+lifetime. High particle densities may be achieved by entrapment in a stress
+induced potential. We consider a multi-component gas of interacting para- and
+orthoexcitons in cuprous oxide confined in a three-dimensional potential trap.
+Based on the Hartree-Fock-Bogoliubov theory, we calculate density profiles as
+well as decay luminescence spectra which exhibit signatures of the separation
+of the Bose-condensed phases.",1010.4171v1
+2011-01-08,Synthesis and Thermal Stability of Cubic ZnO in the Salt Nanocomposites,"Cubic zinc oxide (rs-ZnO), metastable under normal conditions, was
+synthesized from the wurtzite modification (w-ZnO) at 7.7 GPa and ~800 K in the
+form of nanoparticles isolated in the NaCl matrix. The phase transition rs-ZnO
+\rightarrow w-ZnO in nanocrystalline zinc oxide under ambient pressure was
+experimentally studied for the first time by differential scanning calorimetry
+and high-temperature X-ray diffraction. It was shown that the transition occurs
+in the 370-430 K temperature range and its enthalpy at 400 K is -10.2 \pm 0.5
+kJ mol-1.",1101.1588v1
+2011-01-17,Imprinting nanoporous alumina patterns into the magneto-transport of oxide superconductors,"We used oxygen ion irradiation to transfer the nanoscale pattern of a porous
+alumina mask into high- superconducting thin films. This causes a nanoscale
+spatial modulation of superconductivity and strongly affects the
+magneto-transport below, which shows a series of periodic oscillations
+reminiscent of the Little-Parks effect in superconducting wire networks. This
+irradiation technique could be extended to other oxide materials in order to
+induce ordered nanoscale phase segregation.",1101.3172v1
+2011-01-18,Metal-insulator transition and electrically-driven memristive characteristics of SmNiO3 thin films,"The correlated oxide SmNiO3 (SNO) exhibits an insulator to metal transition
+(MIT) at 130 {\deg}C in bulk form. We report on synthesis and electron
+transport in SNO films deposited on LaAlO3 (LAO) and Si single crystals. X-ray
+diffraction studies show that compressively strained single-phase SNO grows
+epitaxially on LAO while on Si, mixed oxide phases are observed. MIT is
+observed in resistance-temperature measurements in films grown on both
+substrates, with charge transport in-plane for LAO/SNO films and out-of-plane
+for Si/SNO films. Electrically-driven memristive behavior is realized in
+LAO/SNO films, suggesting that SNO may be relevant for neuromorphic devices.",1101.3538v1
+2011-02-04,Initial oxidation of Fe-Al and Fe-Cr-Al alloys: Cr as an alumina booster,"The boosting effect of Cr on the growth of the protective alumina scale on
+Fe-Al alloys is investigated by x-ray photoelectron spectroscopy. Using low
+oxygen pressure the surface chemistry of the alloys is monitored starting from
+the first moments of oxidation. Chromium effect on the Fe-Al surface-bulk
+exchange is clearly detected by analyzing the measured surface concentrations
+within the atomic concentration models. Previous ab initio calculations agree
+well with the present experiments.",1102.0912v1
+2011-03-09,Self-consistent model of unipolar transport in organic semiconductor diodes: accounting for a realistic density-of-states distribution,"A self-consistent, mean-field model of charge-carrier injection and unipolar
+transport in an organic semiconductor diode is developed utilizing the
+effective transport energy concept and taking into account a realistic
+density-of-states distribution as well as the presence of trap states in an
+organic material. The consequences resulting from the model are discussed
+exemplarily on the basis of an indium tin oxide/organic semiconductor/metallic
+conductor structure. A comparison of the theory to experimental data of a
+unipolar indium tin oxide/poly-3-hexyl-thiophene/Al device is presented.",1103.1752v1
+2011-05-21,LaCrO3 heteroepitaxy on SrTiO3(001) by molecular beam epitaxy,"Stoichiometric, epitaxial LaCrO3 films have been grown on TiO2-terminated
+SrTiO3(001) substrates by molecular beam epitaxy using O2 as the oxidant. Film
+growth occurred in a layer-by-layer fashion, giving rise to structurally
+excellent films and surfaces which preserve the step-terrace structure of the
+substrate. The critical thickness is in excess of 500 {\AA}. Near-surface
+Cr(III) is highly susceptible to further oxidation to Cr(V), leading to the
+formation of a disordered phase upon exposure to atomic oxygen. Recovery of the
+original epitaxial LaCrO3 phase is readily achieved by vacuum annealing.",1105.4290v1
+2011-06-14,Rigorous definition of oxidation states of ions in solids,"We present justification and rigorous procedure for electron partitioning
+among atoms in extended systems. The method is based on wavefunction topology
+and the modern theory of polarization, rather than charge density partitioning
+or wavefunction projection, and, as such, re-formulates the concept of
+oxidation state without assuming real-space charge transfer between atoms. This
+formulation provides rigorous electrostatics of finite extent solids, including
+films and nanowires.",1106.2836v2
+2011-08-03,Reduction of the Casimir force from indium tin oxide film by UV treatment,"A significant decrease in the magnitude of the Casimir force (from 21% to
+35%) was observed after an indium tin oxide (ITO) sample interacting with an Au
+sphere was subjected to the UV treatment. Measurements were performed by using
+an atomic force microscope (AFM) in high vacuum. The experimental results are
+compared with theory, and a hypothetical explanation for the observed
+phenomenon is proposed.",1108.0923v1
+2011-08-16,Re-determination of the Pseudobinary System Li2O-MoO3,"The quasi-binary phase diagram lithium oxide - molybdenum(VI) oxide was
+investigated by differential scanning calorimetry and X-ray diffraction. The
+four intermediate phases Li4MoO5, Li2MoO4, Li4Mo5O17, and Li2Mo4O13 show
+incongruent melting. The system has one eutectic point at 50.5 mol% MoO3 and
+49.5 mol% LiO0.5 with a eutectic temperature of 524.6 deg C. At this point the
+melt is in equilibrium with Li2MoO4 and Li4Mo5O17.",1108.3248v1
+2011-08-30,Ferroelectricity in Silver Perovskite Oxides,"There are two silver perovskite oxides: AgNbO3 and AgTaO3. AgNbO3 has a
+noncentrosymmetric group of Pmc21 at room temperature with a ferri-electric
+ordering of polarization. Such a ferri-electric state with small polarization
+can be changed into a ferroelectric state with very large polarization by a
+high electric field or by a chemical modification. The induced ferroelectric
+phase shows promising electromechanical response for applications in
+piezoelectric devices. In contrast, AgTaO3 is a quantum paraelectric, but
+ferroelectricity also can be induced through chemical substitution. The
+findings of good ferroelectric and piezoelectric performance in the silver
+perovskites are hoped to trigger further theoretical and experimental
+investigations on these systems.",1108.5819v1
+2011-09-14,Electric field induced reversible control of visible photoluminescence from ZnO nanoparticles,"Reversible control of the photoluminescence of ZnO occurring in the visible
+range, has been achieved by application of a few volts (< 5V) to a device
+consisting of nanostructured ZnO film sandwiched between Indium Tin Oxide
+electrode and polyethylene oxide-lithium perchlorate, a solid polymer
+electrolyte. The photoluminescence intensity shows nearly 100% modulation with
+a response time less than 30 seconds, when the bias is applied at the
+electrolyte-electrode. A model is proposed for the observed effect that is
+based on defect states of ZnO and the band bending at the ZnO-electrolyte
+interface that can be changed by the applied bias.",1109.2968v1
+2011-10-27,Intrinsic Cut-off Frequency in Scaled Graphene Transistors,"Using 2-D self-consistent ballistic quantum transport simulations, we
+investigate the short-channel behavior of graphene field-effect transistors and
+its impact on the device transconductance and subsequently the intrinsic
+cut-off frequency (fT). Although with thin oxides, fT expectedly scales
+inversely with the gate length, significant band-to-band tunneling at OFF state
+leads to a departure from this trend in case of thick oxides. We also examine
+the effect of achieving better electrostatics at the cost of increased gate
+capacitance and illustrate that this can indeed degrade the fT. These
+considerations should be implicit in the optimization of graphene transistors
+for high-frequency applications.",1110.6211v1
+2012-03-06,Reduction of Copper Oxide by Formic Acid an ab-initio study,"Four cluster models for a copper(I)oxide (111) surface have been designed, of
+which three were studied with respect to their applicability in density
+functional calculations in the general gradient approximation. Formic acid
+adsorption on these systems was modelled and yielded four different adsorption
+structures, of which two were found to have a high adsorption energy. The
+energetically most favourable adsorption structure was further investigated
+with respect to its decomposition and a few reactions with adsorbed H and OH
+species using synchronous transit methods to estimate reaction barriers and
+single point energy calculations for the reaction energy.",1203.1163v1
+2012-08-27,STM-induced surface aggregates on metals and oxidized silicon,"We have observed an aggregation of carbon or carbon derivatives on platinum
+and natively oxidized silicon surfaces during STM measurements in ultra-high
+vacuum on solvent-cleaned samples previously structured by e-beam lithography.
+We have imaged the aggregated layer with scanning tunneling microscopy (STM) as
+well as scanning electron microscopy (SEM). The amount of the aggregated
+material increases with the number of STM scans and with the tunneling voltage.
+Film thicknesses of up to 10 nm with five successive STM measurements have been
+obtained.",1208.5336v1
+2012-10-07,Types of single particle symmetry breaking in transition metal oxides due to electron correlation,"Very accurate wave functions are calculated for small transition metal oxide
+molecules. These wave functions are decomposed using reduced density matrices
+to study the underlying correlation of electrons. The correlation is primarily
+of left-right type between the transition metals and the oxygen atoms, which is
+mediated by excitations from the nominal single Slater ground state into
+antibonding and d-type orbitals. In a localized representation, this
+correlation manifests itself in a 2-electron hopping term that is off-diagonal.
+This term is of similar magnitude to the commonly considered Hubbard-type
+on-site interaction.",1210.2115v2
+2012-11-22,Observation of Phonon-Assisted Magnon Absorption in Spin-Orbit Coupling Induced Mott Insulator Sr$_{2}$IrO$_{4}$,"The infrared transmission measurement was performed for a two-dimensional
+spin-orbit coupling induced Mott insulator Sr$_{2}$IrO$_{4}$ with a
+layered-perovskite structure. A phonon-assisted magnon mode was observed at
+around 1870 cm$^{-1}$ in the absorption spectrum below 180 K. The
+nearest-neighbor superexchange interaction $J$ was estimated to be 57 meV,
+which is about a half of the $J$ value of a copper oxide La$_{2}$CuO$_{4}$. Our
+results indicate the possibility that nontrivial properties such as
+superconductivity are realized at rather high temperature in iridium oxides.",1211.5241v2
+2012-12-02,"Linearly polarized, Q-switched Er-doped fiber laser based on reduced graphene oxide saturable absorber","We demonstrate generation of linearly polarized pulses from a passively
+Q-switched Erbium-doped fiber laser. The cavity was designed using only
+polarization maintaining (PM) fibers and components, resulting in linearly
+polarized output beam with degree of polarization (DOP) at the level of 97.6%.
+Reduced graphene oxide (rGO) was used as a saturable absorber for Q-switched
+operation. The laser was capable of delivering 1.85us pulses with 125nJ pulse
+energy at 115kHz repetition rate.",1212.0201v1
+2012-12-04,Anion-radical oxygen centers in small (AgO)n clusters: density functional theory predictions,"Anion-radical form of the oxygen centers O(-) is predicted at the DFT level
+for small silver oxide particles having the AgO stoichiometry. Model clusters
+(AgO)n appear to be ferromagnetic with appreciable spin density at the oxygen
+centers. In contrast to these clusters, the Ag2O model cluster have no unpaired
+electrons in the ground state. The increased O/Ag ratio in the oxide particles
+is proved to be responsible for the spin density at oxygen centers.",1212.0712v1
+2013-03-16,Designing ferromagnetism in vanadium-oxide based superlattices,"Motivated by recent reports (Phys. Rev. B\textbf{80}, 241102) of
+room-temperature ferromagnetism in vanadium-oxide based superlattices, a
+single-site dynamical mean field study of the dependence of the
+paramagnetic-ferromagnetic phase boundary on superlattice geometry was
+performed. An examination of variants of the experimentally determined crystal
+structure indicate that ferromagnetism is found only in a small and probably
+inaccessible region of the phase diagram. Design criteria for increasing the
+range over which ferromagnetism might exist are proposed.",1303.4016v2
+2013-04-10,Single Hole Transport in a Silicon Metal-Oxide-Semiconductor Quantum Dot,"We describe a planar silicon metal-oxide-semiconductor (MOS) based single
+hole transistor, which is compatible with conventional Si CMOS fabrication. A
+multi-layer gate design gives independent control of the carrier density in the
+dot and reservoirs. Clear Coulomb blockade oscillations are observed, and
+source-drain biasing measurements show that it is possible to deplete the dot
+down to the few hole regime, with excited states clearly visible. The
+architecture is sufficiently versatile that a second hole dot could be induced
+adjacent to the first one.",1304.2871v2
+2013-06-30,Effect of encapsulated graphene oxide on alginate-based bead adsorption to remove acridine orange from aqueous solutions,"Environmentally-benign high-performance graphene oxide (GO)/alginate-based
+absorbents were prepared to eliminate acridine orange selected as a typical
+dye. Characterizations demonstrated GO well encapsulated and its promotion of
+pore formation on structure. Kinetic studies exhibited that the addition of GO
+shortened the adsorption equilibrium time, raised the initial rate and the
+adsorption capacity. Isotherm studies indicated the adsorptive behavior
+followed Langmuir type, and higher maximum capacity was obtained in the
+presence of GO. The adsorption positively responded to pH increased from acidic
+to weakly alkaline. At low pH, GO would contribute dominantly to the
+adsorption, whereas alginate component was inhibited.",1307.0223v1
+2013-07-03,Simple approach for detection and estimation of photoactivity of silver particles on graphene oxide in aqueous-organic dispersion,"In the aqueous-organic (containing dimethylformamide) dispersion of graphene
+oxide flakes with deposited thereon Ag-particles, under the action of light in
+visible range, apparently for the first time, the effect of sediment flotation
+was observed with subsequent stabilization of the dispersion, which does not
+occur in the absence of Ag-particles. The main reason for such a laser light
+induced movement of sediment GO flakes may be explained with the appearance of
+small bubbles. The further development of this approach seem to be able to
+estimate photo activity of graphene flakes with different activation particles.",1307.0926v1
+2013-10-17,Improved Interfacial and Electrical Properties of GaSb Metal Oxide Semiconductor Devices Passivated with Acidic (NH4)2S Solution,"Surface passivation with acidic (NH4)2S solution is shown to be effective in
+improving the interfacial and electrical properties of HfO2/GaSb metal oxide
+semiconductor devices. Compared with control samples, those treated with acidic
+(NH4)2S solution showed great improvements in frequency dispersion, gate
+leakage current and interface trap density. These improvements were attributed
+to the acidic (NH4)2S solution enhancing passivation of the substrates, which
+was analyzed from the perspective of chemical mechanism and confirmed by X-ray
+photoelectron spectroscopy and high-resolution cross-sectional transmission
+electron microscopy.",1310.4591v1
+2013-11-14,Photo-oxidation of Graphene in the Presence of Water,"Oxygen molecules are found to exhibit non-negligible reactivity with graphene
+under strong light irradiation in the presence of water. The reaction is
+triggered by the laser Raman spectroscopy measurement itself, and the D band
+(ca. 1340 cm-1) becomes larger as the laser irradiation is prolonged. The
+electronic transport properties of the graphene derivative are also
+investigated and both the electron and hole mobility are found to be reduced.
+These results are attributed to oxidation of graphene. This primitive
+modification method can be exploited to manipulate the structural and
+electronic properties of graphene.",1311.3447v1
+2013-12-13,Room temperature formation of high-mobility two-dimensional electron gases at crystalline complex oxide interfaces,"Well-controlled sub-unit-cell layer-by-layer epitaxial growth of spinel
+alumina is achieved at room temperature on the TiO2-terminated SrTiO3 single
+crystalline substrate. By tailoring the interface redox reaction,
+two-dimensional electron gases with mobilities exceeding 3000 cm2V-1s-1 are
+achieved at this novel oxide interface.",1312.3719v1
+2013-12-27,Third Harmonic Generation in Cuprous Oxide: Efficiency Determination,"The efficiency of third harmonic generation in cuprous oxide was measured.
+Intensities followed a non-cubic power law which indicates nonperturbative
+behavior. Polarization anisotropy of the harmonic generation was demonstrated
+and related to the third order susceptibility. The results will influence the
+understanding of harmonic generation in centrosymmetric materials and are
+potentially relevant to device design and the interpretation of exciton
+behavior.",1312.7371v1
+2013-12-27,Unexpectedly Slow Two Particle Decay of Ultra-Dense Excitons in Cuprous Oxide,"For an ultra-dense exciton gas in cuprous oxide (Cu$_2$O), exciton-exciton
+interactions are the dominant cause of exciton decay. This study demonstrates
+that the accepted Auger recombination model overestimates the exciton decay
+rate following intense two photon excitation. Two exciton decay is relevant to
+the search for collective quantum behavior of excitons in bulk systems. These
+results suggest the existence of a new high density regime of exciton behavior.",1312.7372v1
+2014-01-06,Band offsets in heterojunctions between cubic perovskite oxides,"The band offsets for nine heterojunctions between titanates, zirconates, and
+niobates with the cubic perovskite structure were calculated from first
+principles. The effect of strain in contacting oxides on their energy
+structure, many-body corrections to the position of the band edges (calculated
+in the GW approximation), and the splitting of the conduction band resulting
+from spin-orbit interaction were consistently taken into account. It was shown
+that the neglect of the many-body effects can lead to errors in determination
+of the band offsets up to 0.36 eV. The failure of the transitivity rule, which
+is often used to determine the band offsets in heterojunctions, was
+demonstrated and its cause was explained.",1401.1157v1
+2014-01-09,Functionalization of Amorphous Chalcogenide and Titanium Oxide Layers by Gold Nanoparticles,"The technology problems of fabricating different, nanometers sized gold
+particles in the layered composites like light-sensitive chalcogenide
+glass/gold nanoparticles/transparent substrate or titanium/titanium oxide/gold
+nanoparticles were investigated in our work. Combination of ion implantation,
+plasma deposition with annealing processes results physical routes for creation
+of gold nanoparticles in the mentioned structures, which possess plasmon
+effects. These functionalized structures are planned to use for investigations
+of optical recording processes, biocompatibility of titanium implants.",1401.1963v1
+2014-01-09,Microwave Assisted Synthesis and Characterization of Perovskite Oxides,"The use of microwave irradiation is a promising alternative heat source for
+the synthesis of inorganic materials such as perovskite oxides. The method
+offers massive energy and time savings as compared to the traditional ceramic
+method. In this work we review the basic principles of the microwave heating
+mechanism based on interactions between dipoles in the material and the
+electromagnetic microwave. Furthermore, we comment on and classify all
+different sub-types of microwave synthesis such as solid-state microwave and
+microwave assisted hydrothermal synthesis. In the experimental part of this
+work we present a large range of materials that were synthesized in our
+laboratories by one of the microwave techniques, where such materials include
+superconducting, ferromagnetic, ferroelectric, dielectric and multiferroic
+perovskite systems.",1401.1965v1
+2014-01-15,X-ray absorption spectroscopy characterization of iron-oxide nanoparticles synthesized by high temperature plasma processing,"Iron-oxide nanoparticles have been synthesized by high temperature arc plasma
+route with different plasma currents and characterized for their structure,
+morphology and local atomic order. Fe K-edge x-ray absorption spectra reveal
+distinct local structure of the samples grown with different plasma currents.
+We have shown that the local disorder is higher for the higher plasma current
+grown samples that also have a larger average particle-size. The results
+provide useful information to control structural and morphological properties
+of nanoparticles grown by high temperature plasma synthesis process.",1401.3655v1
+2014-01-17,Solution-Processable Graphene Oxide as an Efficient Hole Injection Layer for High Luminance Organic Light-Emitting Diodes,"The application of solution-processable graphene oxide (GO) as hole injection
+layer in organic light-emitting diodes (OLEDs) is demonstrated. High luminance
+of over 53,000 cd m-2 is obtained at only 10 V. The results will unlock a route
+of applying GO in flexible OLEDs and other electrode applications.",1401.4427v1
+2014-02-11,Scaling properties in the adsorption of ionic polymeric surfactants on generic nanoparticles of metallic oxides by mesoscopic simulation,"We study the scaling of adsorption isotherms of polyacrylic dispersants on
+generic surfaces of metallic oxides $XnOm$ as a function of the number of
+monomeric units, using Electrostatic Dissipative Particle Dynamics simulations.
+The simulations show how the scaling properties in these systems emerge and how
+the isotherms rescale to a universal curve, reproducing reported experimental
+results. The critical exponent for these systems is also obtained, in perfect
+agreement with the scaling theory of deGennes. Some important applications are
+mentioned.",1402.2661v1
+2014-09-29,Cross-phase modulation instability in mode-locked laser based on reduced graphene oxide,"Cross-phase modulation instability (XPMI) is experimentally observed in a
+fiber ring cavity with net normal dispersion and mode-locked by long fiber
+taper. The taper is deposited with reduced graphene oxide, which can decrease
+the threshold of XPMI due to the enhanced nonlinearity realized by 8 mm
+evanescent field interaction length and strong mode confinement. Experimental
+results indicate that the phase matching conditions in two polarization
+directions are different, and sidebands with different intensities are
+generated. This phase matching condition can be satisfied even the polarization
+state of the laser varies greatly under different pump strengths.",1409.8210v1
+2014-11-09,Application of gold in the field of heterogeneous catalysis,"Gold has been long thought as an inert metal which finds most of its use in
+jewelry and monetary exchange. However, catalysis by gold has rapidly become a
+hot topic in chemistry ever since Haruta and Hutchings found gold to be an
+extraordinary good heterogeneous catalyst in certain reactions. Here in this
+paper, several model reactions which made gold historically famous as a
+catalyst and a currently hot topic will be demonstrated, such as oxidation of
+CO, selective oxidation, and hydrodechlorination. Conclusions on the chemical
+nature of gold will be made as well as future perspectives of designing gold as
+a better catalyst.",1411.2583v1
+2014-12-15,Pinball liquid phase from Hund's coupling in frustrated transition metal oxides,"The interplay of non-local Coulomb repulsion and Hund's coupling in the
+d-orbital manifold in frustrated triangular lattices is analyzed by a mutliband
+extended Hubbard model. We find a rich phase diagram with several competing
+phases, including a robust pinball liquid phase, which is an unconventional
+metal characterized by threefold charge order, bad metallic behavior and the
+emergence of high spin local moments. Our results naturally explain the
+anomalous charge-ordered metallic state observed in the triangular layered
+compound AgNiO2. The potential relevance to other triangular transition metal
+oxides is discussed.",1412.4696v2
+2014-12-23,Effects of Manganese Addition on the Electronic Structure of BaTiO$_3$,"Mn is used as a dopant to improve the electromechanical properties of
+perovskite oxides. We elucidate the role of Mn defects and associated vacancies
+on the electronic, atomic and ferroelectric properties of BaTiO$_3$. Using
+density functional theory (DFT) and DFT+U we investigate the equilibrium
+geometry and electronic properties of Mn ion on A or B sites and with
+compensating oxygen vacancies. We study the change in the oxidation state of Mn
+in response to local environment changes, such as the presence of oxygen
+vacancies.",1412.7458v1
+2015-01-09,Enhancing triplet superconductivity by the proximity to a singlet superconductor in oxide heterostructures,"We show how in principle a coherent coupling between two superconductors of
+opposite parity can be realized in a three-layer oxide heterostructure. Due to
+strong intraionic spin-orbit coupling in the middle layer, singlet Cooper pairs
+are converted into triplet ones and vice versa. This results in a large
+enhancement of the triplet superconductivity, persisting well above the native
+triplet critical temperature.",1501.02077v2
+2015-02-10,Strength of the dominant scatterer in graphene on silicon oxide,"A large variability of carrier mobility of graphene-based field effect
+transistors hampers graphene science and technology. We determine the
+scattering strength of the dominant scatterer responsible for the variability
+of graphene-based transistors on silicon oxide. The strength of the scatterer
+is found to be more consistent with charged impurities than with resonant
+impurities.",1502.03043v2
+2015-03-20,Proposed cavity Josephson plasmonics with complex-oxide heterostructures,"We discuss how complex-oxide heterostructures that include high-Tc
+superconducting cuprates can be used to realize an array of sub-millimeter
+cavities that support Josephson plasmon polaritons. These cavities have several
+attractive features for new types of light matter interaction studies and we
+show that they promote ""ultrastrong"" coupling between THz frequency radiation
+and Josephson plasmons. Cavity electrodynamics of Josephson plasmons allows to
+manipulate the superconducting order-parameter phase coherence. As an example,
+we discuss how it could be used to cool superconducting phase fluctuations with
+light.",1503.06117v2
+2015-04-03,Plane Wave Density Functional Theory Studies of the Structural and the Electronic Properties of Amino Acids Attached to Graphene Oxide via Peptide Bonding,"We studied the electronic and the structural properties of amino acids
+(alanine, glycine, and histidine) attached to graphene oxide (GO) by peptide
+bonding, via plane wave pseudopotential total-energy calculations within the
+local spin density approximation (LSDA). The HOMO-LUMO gap, the Hirshfeld
+charges, and the equilibrium geometrical structures exhibit keen variations
+depending on the species of the attached amino acid. The GO-amino acid system
+appears to be a good candidate as a biosensor.",1504.00741v1
+2015-06-26,Characterizing the Structure of Topological Insulator Thin Films,"We describe the characterization of structural defects that occur during
+molecular beam epitaxy of topological insulator thin films on commonly used
+substrates. Twinned domains are ubiquitous but can be reduced by growth on
+smooth InP (111)A substrates, depending on details of the oxide desorption.
+Even with a low density of twins, the lattice mismatch between (Bi,Sb)2Te3 and
+InP can cause tilts in the film with respect to the substrate. We also briefly
+discuss transport in simultaneously top and back electrically gated devices
+using SrTiO3 and the use of capping layers to protect topological insulator
+films from oxidation and exposure.",1506.08175v1
+2015-09-23,Optical Properties of ITO/ZnO Schottky Diode with Enhanced UV Photoresponse,"Photoluminescence (PL) spectra of zinc oxide (ZnO) samples with different
+hydrogen peroxide (H2O2) treatment durations were measured to examine several
+point defects on the surface of the films. These results suggest successful
+oxidation through the reaction between oxygen radicals dissociated from H2O2
+and the ZnO surface. To further confirm the defect induced gain mechanism, we
+fabricate highly transparent Schottky diodes, and measure the key diode
+characteristics. Photocurrents are measured under different wavelengths, and
+possible explanations of the high optical gain within the ultraviolet (UV)
+region are provided.",1509.06871v1
+2015-10-18,Quasiparticle Mass Enhancement and Fermi Surface Shape Modification in Oxide Two-Dimensional Electron Gases,"We propose a model intended to qualitatively capture the electron-electron
+interaction physics of two-dimensional electron gases formed near
+transition-metal oxide heterojunctions containing $t_{2g}$ electrons with a
+density much smaller than one electron per metal atom. Two-dimensional electron
+systems of this type can be described perturbatively using a $GW$ approximation
+which predicts that Coulomb interactions enhance quasiparticle effective masses
+more strongly than in simple two-dimensional electron gases, and that they
+reshape the Fermi surface, reducing its anisotropy.",1510.05299v1
+2016-01-23,"Vanadium Dioxide: Metal-Insulator Transition, Electrical Switching and Oscillations. A Review of State of the Art and Recent Progress","Vanadium dioxide is currently considered as one of the most promising
+metarials for oxide elcteronics. Both planar and sandwich thin-film MOM devices
+based on VO2 exhibit electrical switching with an S-shaped I-V characteristic,
+and this switching effect is associated with the metal-insulator transition
+(MIT). In an electrical circuit containing such a switching device, relaxation
+oscillations are observed if the load line intersects the I-V curve at a unique
+point in NDR region. All these effects are potentially prospective for
+designing various devices of oxide electronics, particularly, elements of
+dynamical neural networks based on coupled oscillators.",1601.06246v1
+2016-02-16,N-Type Oxide Thermoelectrics Via Visual Search Strategies,"We discuss and present search strategies for finding new thermoelectric
+compositions based on first principles electronic structure and transport
+calculations. We illustrate them by application to a search for potential
+n-type oxide thermoelectric materials. This includes a screen based on
+visualization of electronic energy isosurfaces. We report compounds that show
+potential as thermoelectric materials along with detailed properties, including
+SrTiO3, which is a known thermoelectric, and appropriately doped KNbO3 and
+rutile TiO2.",1602.05054v1
+2016-04-15,The growth mechanism of CuO nanowires synthesized by the thermal oxidation method,"Large-scale CuO nanowires are commonly synthesized by the thermal oxidation
+method. However, the growth mechanism remains controversial between diffusion
+growth mechanism and vapor-solid (VS) growth mechanism. In this study, we
+investigated the morphology and atomic structure of the CuO nanowires by
+electron microscopes to clarify the growth mechanism. We found that they were
+grown with the annealing ambient during the cooling process and there were
+screw dislocations in the nanowires. These features indicate that the VS growth
+mechanism is applicable to explain the growth of the CuO nanowires. In
+addition, the kinetic consideration also supports the VS growth mechanism.",1604.04411v2
+2016-04-29,Monolithic AlGaAs second-harmonic nanoantennas,"We demonstrate monolithic aluminum gallium arsenide (AlGaAs) optical
+anoantennas. Using a selective oxidation technique, we fabricate such epitaxial
+semiconductor nanoparticles on an aluminum oxide substrate. Second harmonic
+generation from an AlGaAs nanocylinder of height h=400 nm and varying radius
+pumped with femtosecond pulses delivered at 1554-nm wavelength has been
+measured, revealing a peak conversion efficiency exceeding 10-5 for
+nanocylinders with an otpimized geometry.",1604.08881v1
+2016-06-08,"Can we prevent the ""dead layer"" formation at manganite interfaces?","The present work theoretically studies the possibility to hinder the
+formation of a ""dead"" layer at the interfaces in manganite superlattices. We
+showed that this goal can be reached by using alkaline-earth simple oxides as
+alternating layers in very thin superlattices. Indeed, such alternating layer
+promotes the contraction of manganite layers at the interfaces and
+$d_{x^2-y^2}$ preferred $e_g$ orbital occupancy, while Boltzman's transport
+calculations show an increase in conductivity. This result hold for different
+manganites, different alkaline-earth simple oxides as well as different
+thicknesses of the two layers.",1606.02764v1
+2016-10-06,Temperature dependence of long coherence times of oxide charge qubits,"The ability to maintain coherence and control in a qubit is a major
+requirement for quantum computation. We show theoretically that long coherence
+times can be achieved above boiling point of liquid helium in charge qubits of
+oxide double quantum dots. Detuning the dots to a fraction of the optical
+phonon energy, increasing the electron-phonon coupling, reducing the
+adiabaticity, or decreasing the temperature enhances the coherence time. We
+consider a system that is initially decoupled from the phonon bath in the
+polaronic frame of reference and solve the non-Markovian quantum master
+equation; we find that the system decoheres after a long time, despite the fact
+that no energy is exchanged with the bath.",1610.01866v1
+2016-10-12,Anodic TiO2 nanotube layers: why does self-organized growth occur - A mini review,"The present review gives an overview of the highlights of more than 10 years
+of research on synthesis and applications of ordered oxide structures (nanotube
+layers, hexagonal pore arrangements) that are formed by self-organizing
+anodization of metals. In particular we address the questions after the
+critical factors that lead to the spectacular self-ordering during the growth
+of anodic oxides that finally yield morphologies such as highly ordered TiO2
+nanotube arrays and similar structures. Why are tubes and pores formed - what
+are the key parameters controlling these processes?",1610.03643v1
+2016-10-13,Ar+-ion Bombardment of TiO2 Nanotubes Creates Co-catalytic Effect for Photocatalytic Open Circuit Hydrogen Evolution,"In the present work, extended Argon ion bombardment was used to modify
+anatase TiO2 nanotube (NTs) layers. In situ X-ray photoelectron spectroscopy
+revealed a high content of sub-oxide formed (Ti3+, Ti2+ states) in the nanotube
+layers. These samples were tested for their ability to show open-circuit
+photocatalytic hydrogen evolution. We found for UV (cw laser 325nm)
+illumination as well as for AM1.5 conditions, a strongly enhanced H2 evolution
+activity in absence of the usual noble metal-nanoparticle decoration. We
+conclude therefore that these sub-oxide states can play an important role in
+the activation of TiO2 nanotubes - namely as a H2 evolution co-catalyst.",1610.04136v1
+2017-02-11,Oxides in an oxygen potential gradient: coupled morphological stability of the multiple phase boundaries,"In materials that are exposed to thermodynamic potential gradients, i.e.,
+gradients of chemical potentials, electrical potential, temperature, or
+pressure, transport processes of the mobile components occur. These transport
+processes and the coupling between different processes are not only of
+fundamental interest, but are also the origin of several degradation processes,
+such as kinetic unmixing and decomposition. In addition, changes in the
+morphology of the material surfaces and interfaces may appear. In this paper, a
+comprehensive formal treatment of the coupled morphological stability of
+multiple phase boundaries will be given for oxides that are exposed to an
+oxygen potential gradient.",1702.04238v1
+2017-02-21,Flexible Transparent Field-Effect Diodes Fabricated at Low-Temperature with All Oxide Materials,"Flexible fully transparent diodes with high rectification ratio of 5 e 8 are
+fabricated with all oxide materials at low temperature. The devices are
+optically transparent in visible spectra range and electrically robust while
+mechanically bending. Distinguished from other diodes, these diodes utilize
+diode-connected thin-film transistor architecture and follow field-effect
+principles.",1702.06351v1
+2018-02-16,The mechanisms of hot salt stress corrosion cracking in titanium alloy Ti-6Al-2Sn-4Zr-6Mo,"Hot salt stress corrosion cracking in Ti 6246 alloy has been investigated to
+elucidate the chemical mechanisms that occur. Cracking was found to initiate
+beneath salt particles in the presence of oxidation. The observed transgranular
+fracture was suspected to be due to hydrogen charging; XRD and high-resolution
+transmission electron microscopy detected the presence of hydrides that were
+precipitated on cooling. SEM-EDS showed oxygen enrichment near salt particles,
+alongside chlorine and sodium. Aluminium and zirconium were also involved in
+the oxidation reactions. The role of intermediate corrosion products such as
+Na2TiO3, Al2O3, ZrO2, TiCl2 and TiH are discussed.",1802.06045v1
+2018-04-20,Redox reaction enhanced Schottky contact at a \LNO{}(001)/Al interface,"Emergent phenomena at interfaces between oxides and metals can appear due to
+charge transfer and mass transport that modify the bulk properties. By coating
+the metallic oxide LaNiO$_3$ by aluminium, we fabricated a junction exhibiting
+a diode-like behaviour. At the equilibrium, the interface is insulating. The
+metallic behaviour can be recovered by applying a voltage drop across the
+junction in one polarity only. The electrical properties in direct and reverse
+bias are investigated. The observed electro-resistive effect rises up to $10^5$
+\% and can be interpreted in terms of (i) a spontaneous redox reaction
+occurring at the interface and (ii) its reversal induced by charge injection in
+direct bias.",1804.07574v1
+2018-10-08,Carbon Monoxide Adsorption and Carbon Monoxide Oxidation Studies on Thiolate Supported Gold Nanoclusters Dispensed on Metallic Oxides,"Thiolate-protected gold nanoclusters represent atomically well-defined active
+centers for catalysis with resolved crystal structures, enabling the creation
+of a homogeneous and defined surface. The correlation of characterization via
+FT-IR spectroscopy with kinetics studies gives insight into the gold clusters
+activity and tests their utilization to bridge the gap between organometallic
+complex-based homogenous catalysis and nanoparticle based heterogeneous
+catalysis as well as the gap between the bulk crystal structure model catalysis
+and real-world catalysis.",1811.01999v1
+2018-11-17,Fluorescence coherence with anodic aluminum oxide hybrid photonic-plasmonic structure,"A class of hybrid photonic-plasmonic structures (HPPS) with vertical
+cylindrical cavities is proposed and its performance in providing a coherent
+light from spontaneous emission is investigated. It is shown that the proposed
+easy-to-fabricate and robust anodic aluminum oxide structure dramatically
+enhances the temporal and spatial coherence compared to the previously examined
+HPPS. The physical mechanism of achieving the temporal and spatial coherence is
+explained based on the special optical properties of the proposed HPPS and it
+is discussed how this structure enables one adjusting hybrid photonic-plasmonic
+optical modes to obtain coherence for emitters of different frequencies.",1811.10465v3
+2019-05-07,Band gap evolution in Ruddlesden-Popper phases,"We investigate the variation of the band gap across the Ruddlesden-Popper
+(RP) series (An+1BnX3n+1) in model chalcogenide, oxide, and halide materials to
+understand the factors influencing band gap evolution. In contrast to the
+oxides and halides, we find the band gap of the chalcogenides evolve
+differently with the thickness of the perovskite blocks in these natural
+superlattices. We show that octahedral rotations (i.e. deviation of the B-X-B
+bond angles from 180) and quantum confinement effects compete to decide the
+band gap evolution of RP phases. The insights gained here will allow us to
+rationally design layered perovskite phases for electronics and
+optoelectronics.",1905.02598v1
+2020-07-15,Roughness and scaling properties of oxide glass surfaces at the nanoscale,"Using atomistic computer simulations we determine the roughness and
+topographical features of melt-formed (MS) and fracture surfaces (FS) of oxide
+glasses. We find that the topography of the MS is described well by the frozen
+capillary wave theory. The FS are significant rougher than the MS and depend
+strongly on glass composition. The height-height correlation function for the
+FS shows an unexpected logarithmic dependence on distance, in contrast to the
+power-law found in experiments. We thus conclude that on length scales less
+than 10 nm FS are not self-affine fractals.",2007.07474v1
+2010-05-31,Transparent and flexible polymerized graphite oxide thin film with frequency-dependent dielectric constant,"Here we report on the preparation of transparent and flexible polymerized
+graphite oxide, which is composed of carbons with sp3-hybridized orbitals and a
+non-planar ring structure, and which demonstrates dispersion in its dielectric
+constant at room temperature. This frequency dependence renders the material
+suitable for creating miniaturized, flexible, and transparent variable
+capacitors, allowing for smaller and simpler integrated electronic devices. We
+discuss this polarizability in terms of space charge effects.",1005.5576v1
+2013-08-02,Electronic structure modification of Si-nanocrystals with F4 -TCNQ,"We use first-principles models to demonstrate how an organic oxidizing agent,
+F4 -TCNQ (7,7,8,8- tetracyano-2,3,5,6-tetrafluoroquinodimethane), modifies the
+electronic structure of silicon nanocrys- tals, suggesting it may enhance
+p-type carrier density and mobility. The proximity of the lowest unoccupied
+level of F4 -TCNQ to the highest occupied level of the Si-nanocrystals promotes
+the formation of an empty hybrid state overlapping both nanocrystal and
+molecule, reducing the exci- tation energy to about 0.8-1 eV in vacuum. Hence,
+it is suggested that F4 -TCNQ can serve both as a surface oxidant and a
+mediator for hole hopping between adjacent nanocrystals.",1308.0444v1
+2013-08-05,Optical conductivity of the $t_{2g}$ two-dimensional electron gas,"Motivated by recent interest in perovskite surfaces and heterostructures, we
+present an analysis of the Kubo conductivity of a two-dimensional electron gas
+(2DEG) formed in the $t_{2g}$ bands of an oxide with perovskite structure. We
+find that when the electric field is polarized in the plane of the 2DEG, the
+optical conductivity is dominated by nearly independent Drude contributions
+from two-dimensional subband Fermi surfaces, whereas for perpendicular-to-plane
+polarization it has strong intersubband features. Our analysis suggests that
+perpendicular-to-plane optical conductivity studies may help advance
+understanding of the interplay between lattice distortions and
+electron-electron interactions in complex oxide 2DEG quantum confinement
+physics.",1308.1000v1
+2013-08-25,Breakdown of Fast Water Transport in Graphene Oxides,"Fast slip flow was reported for water inside the interlayer gallery between
+graphene layers or carbon nanotubes. We report here that this flow rate
+enhancement (over two orders) breaks down with the presence of chemical
+functionalization and relaxation of the nanoconfinement in graphene oxides.
+Molecular dynamics simulation results show that hydrodynamics applies in this
+circumstance, even at length scales down to nanometers. However, corrections on
+the slip boundary condition and viscosity of nanoconfined flow must be included
+to make quantitative predictions. These results were discussed with structural
+characteristics of the liquid water and hydrogen bond networks.",1308.5367v1
+2016-11-03,Structural and electrical properties of electrodeposited single junction of cuprous (I) oxide copper,"Cuprous (I) oxide (Cu_{2}O) based solar cells were fabricated with the use of
+the electrodeposition technique at nanometre scale, and the structural,
+morphological and electrical properties were investigated. The Cu_{2}O layers
+were electrodeposited on crystalline and polycrystalline copper substrates. To
+complete the Cu_{2}O/Cu(100) and Cu_{2}O/Cu interfaces as the solar cells the
+top electrodes of silver paste were painted on the rear of Cu_{2}O. The
+theoretical analysis of the current voltage curve was provided to determine the
+values of electrical parameters of the most efficient solar cell of
+Ag/Cu_{2}O/Cu(100) and clearly indicate presence of two Schottky barriers at
+interfaces.",1611.00969v1
+2017-04-17,"Electron counting in solids: oxidation states, partial charges and ionicity","In this short viewpoint, we discuss the assignment of ionic charges in
+solids. We argue that formal oxidation states serve a useful function, and that
+absolute values of partial charges should be interpreted and applied with
+caution; the charge assigned can never be definitive and depends on the type of
+property studied and the type of analysis performed. Careful analysis can be
+used to avoid unphysical conclusions such as a recent report on the Ti(III)
+nature of Ti in stoichiometric TiO$_2$.",1704.05140v1
+2008-07-04,Lattice dynamical calculations of infinite layer iron oxides SrFeO2 and CaFeO2,"We report extensive lattice dynamical calculations of the newly discovered
+infinite-layer iron oxides SrFeO2 and CaFeO2. For SrFeO2, the parameters of the
+interatomic potential have been determined to reproduce the zone-centre phonon
+frequencies reported using ab-initio calculations. Further we have extended the
+potential model for calculations of CaFeO2. The potential parameters are found
+to be transferable between the two compounds, and are used to calculate the
+phonon spectra in the whole Brillouin zone and several thermodynamic properties
+for these compounds. The calculations show fair agreement with the available
+experimental data of structure, thermal expansion, and mean-squared amplitudes
+of the atoms.",0807.0716v1
+2012-01-18,Enhanced two dimensional electron gas charge densities at III-III/I-V oxide heterostructure interfaces,"In this paper, density functional theory calculations are used to explore the
+electronic and atomic reconstruction at interfaces between III-III/I-V oxides.
+In particular, at these interfaces, two dimensional electron gases (2DEGs) with
+twice the interfacial charge densities of the prototypical LaTiO3/SrTiO3
+heterostructure are observed. Furthermore, a significant decrease in the band
+effective masses of the conduction electrons is shown, suggesting that possible
+enhancements in electron mobilities may be achievable. These findings represent
+a framework for chemically modulating 2DEGs, thereby providing a platform
+through which the underlying physics of electron confinement can be explored
+with implications for modern microelectronic devices.",1201.3871v1
+2012-01-31,"Magnetoresistance, noise properties and the Koshino-Taylor effect in the quasi-1D oxide KRu_4O_8","The low temperature electronic and galvanomagnetic transport properties of
+the low dimensional oxide KRu_4O_8 are experimentally considered. A quadratic
+temperature variation of the resistivity is observed to be proportional to the
+residual resistivity. It shows the role of inelastic electron scattering
+against impurities, i.e. a large Koshino-Taylor effect, rather than a
+consequence of strong electronic correlations. In the same temperature range,
+the Kohler rule is not fulfilled. The resistance noise increases also sharply,
+possibly due to a strong coupling of carriers with lattice fluctuations in this
+low dimensional compound.",1201.6474v1
+2012-04-04,Chemical Synthesis of Nano-Sized particles of Lead Oxide and their Characterization Studies,"The quantum dots of semiconductor display novel and interesting phenomena
+that have not been in the bulk material. The color tunability is one of the
+most attractive characteristics in II-VI semiconductor nanoparticles such as
+CdS, ZnS, CdSe, ZnSe and PbO. In this work, the semiconductor lead oxide
+nanoparticles are prepared by chemical method. The average particle size,
+specific surface area, crystallinity index are estimated from XRD analysis. The
+structural, functional groups and optical characters are analyzed with using of
+SEM, FTIR and UV- Visible techniques. The optical band gap value has also been
+determined.",1204.0896v1
+2012-04-30,Graphene Battery made of Low Cost Reduced Graphene Oxide,"Graphene can collect energy from the ambient heat and convert it to
+electricity, which makes it an ideal candidate for the fabrication of
+self-powered devices. However, this technology is suffering the high cost,
+which limits the practical use of it. In this work, we demonstrated that the
+cost can be reduced by using low cost reduced graphene oxide (RGO), graphite
+electrodes and low cost glass substrates. The results showed that this
+technology can be of practical value for the ""battery"" industry.",1204.6688v1
+2014-05-06,Dispersion engineering of high-Q silicon microresonators via thermal oxidation,"We propose and demonstrate a convenient and sensitive technique for precise
+engineering of group-velocity dispersion in high-Q silicon microresonators. By
+accurately controlling the surface-oxidation thickness of silicon microdisk
+resonators, we are able to precisely manage the zero-dispersion wavelength
+while simultaneously further improving the high optical quality of our devices,
+with the optical Q close to a million. The demonstrated dispersion management
+allows us to achieve parametric generation with precisely engineerable emission
+wavelengths, which shows great potential for application in integrated silicon
+nonlinear and quantum photonics.",1405.1224v1
+2016-05-22,"Many body quantum physics in XANES of highly correlated materials, mixed valence oxides and high temperature superconductors","The x-ray absorption near edge structure (XANES), developed in these last 40
+years using synchrotron radiation, is a unique tool probing electronic
+correlations in complex systems via quantum many body final state effects.
+Multi electron excitations have been observed first in the sixties in x-ray
+absorption spectra of atoms and later in molecules and solids. The applications
+of XANES many body final states to probe unique features of electronic
+correlation in heavy fermions, mixed valence systems, mixed valence oxides and
+high temperature superconductors are discussed.",1605.06850v2
+2016-08-25,Two-dimensional Superconductors with Atomic-scale Thicknesses,"Recent progress in two-dimensional superconductors with atomic-scale
+thicknesses is reviewed mainly from the experimental point of view. The
+superconducting systems treated here involve a variety of materials and forms:
+elemental-metal ultrathin films and atomic layers on semiconductor surfaces;
+interfaces and superlattices of heterostructures made of cuprates, perovskite
+oxides, and rare-earth metal heavy-fermion compounds; interfaces of
+electric-double-layer transistors; graphene and atomic sheets of
+transition-metal dichalcogenide; iron selenide and organic conductors on oxide
+and metal surfaces, respectively. Unique phenomena arising from the ultimate
+two-dimensionality of the system and the physics behind them are discussed.",1608.06997v1
+2016-08-28,Unusual Fe-H bonding associated with oxygen vacancies at the (001) surface of Fe3O4,"An unusual Fe-H bonding rather than conventional OH bonding is identified at
+Fe3O4 (001) surface. This abnormal behavior is associated with the oxygen
+vacancies which exist on the surface region but also penetrate deep into the
+bulk Fe3O4. In contrast, OH bonding becomes preferential as generally expected
+on an ozone processed surface, which has appreciably less oxygen vacancies.
+Such bonding site selective behavior, depending on oxygen vacancy
+concentrations, is further confirmed with DFT calculations. The results
+demonstrate an opportunity for tuning the chemical properties of oxide surfaces
+or oxide clusters.",1608.07773v1
+2016-12-05,Determining the energetics of vicinal perovskite oxide surfaces,"The energetics of vicinal SrTiO$_3$(001) and DyScO$_3$(110), prototypical
+perovskite vicinal surfaces, has been studied using topographic atomic force
+microscopy imaging. The kink formation and strain relaxation energies are
+extracted from a statistical analysis of the step meandering. Both perovskite
+surfaces have very similar kink formation energies and exhibit a similar
+triangular step undulation. Our experiments suggest that the energetics of
+perovskite oxide surfaces is mainly governed by the local oxygen coordination.",1612.01381v1
+2017-06-11,On the thermodynamic aspect of zinc oxide polymorphism. Calorimetric study of metastable rock salt ZnO,"The enthalpies of dissolution of metastable rock salt and thermodynamically
+stable wurtzite polymorphs of zinc oxide in aqueous H2SO4 have been measured in
+direct calorimetric experiments at 303 K and 0.1 MPa and the obtained results
+enabled determination of the standard enthalpy of the rock salt-to-wurtzite
+phase transition in ZnO, {\Delta}trH = -11.7+/-0.3 kJ/mol.",1706.03368v1
+2017-06-18,Neuron-inspired flexible memristive device on silicon (100),"Comprehensive understanding of the world's most energy efficient powerful
+computer, the human brain, is an elusive scientific issue. Still, already
+gained knowledge indicates memristors can be used as a building block to model
+the brain. At the same time, brain cortex is folded allowing trillions of
+neurons to be integrated in a compact volume. Therefore, we report flexible
+aluminium oxide based memristive devices fabricated and then derived from
+widely used bulk mono-crystalline silicon (100). We use complementary metal
+oxide semiconductor based processes to layout the foundation for ultra large
+scale integration (ULSI) of such memory devices to advance the task of
+comprehending a physical model of human brain.",1706.05645v1
+2017-06-18,Theoretical evidence for unexpected O-rich phases at corners of MgO surfaces,"Realistic oxide materials are often semiconductors, in particular at elevated
+temperatures, and their surfaces contain undercoordiated atoms at structural
+defects such as steps and corners. Using hybrid density-functional theory and
+ab initio atomistic thermodynamics, we investigate the interplay of
+bond-making, bond-breaking, and charge-carrier trapping at the corner defects
+at the (100) surface of a p-doped MgO in thermodynamic equilibrium with an O2
+atmosphere. We show that by manipulating the coordination of surface atoms one
+can drastically change and even reverse the order of stability of reduced
+versus oxidized surface sites.",1706.05695v1
+2017-06-20,Scaling of the Hall effects beyond the quantum resistance threshold in oxidized CoFeB,"The ordinary and the extraordinary Hall effects were studied in gradually
+oxidized amorphous CoFeB ferromagnets over six orders of resistivity from the
+metallic to the strongly insulating regime. Polarity of the extraordinary Hall
+effect reverses, and the amplitude of both the ordinary and the extraordinary
+Hall effects increases quadratically with resistivity when resistance exceeds
+the quantum resistance threshold. The absolute value of the extraordinary Hall
+effect scales linearly with the ordinary one in the entire range over eight
+orders of magnitude between the metallic and the insulating states. The
+behavior differs qualitatively and quantitatively from theoretically predicted
+and experimentally known in other materials.",1706.06392v1
+2017-06-23,Scanning Microwave Microscopy of Aluminum CMOS Interconnect Lines Buried in Oxide and Water,"Using a scanning microwave microscope, we imaged in water aluminum
+interconnect lines buried in aluminum and silicon oxides fabricated through a
+state-of-the-art 0.13 um SiGe BiCMOS process. The results were compared with
+that obtained by using atomic force microscopy both in air and water. It was
+found the images in water was degraded by only approximately 60% from that in
+air.",1706.07538v1
+2017-10-13,The electronic-structure origin of cation disorder in transition-metal oxides,"Cation disorder is an important design criterion for technologically relevant
+transition-metal (TM) oxides, such as radiation-tolerant ceramics and Li-ion
+battery electrodes. In this letter, we use a combination of first-principles
+calculations, normal mode analysis, and band-structure arguments to pinpoint a
+specific electronic-structure effect that influences the stability of
+disordered phases. We find that the electronic configuration of a TM ion
+determines to which extent the structural energy is affected by site
+distortions. This mechanism explains the stability of disordered phases with
+large ionic radius differences and provides a concrete guideline for the
+discovery of novel disordered compositions.",1710.05097v1
+2019-06-25,Influence of electron-hole plasma on Rydberg excitons in cuprous oxide,"We develop a many-body approach to the behavior of exciton bound states and
+the conduction electron band edge in a surrounding electron-hole plasma with a
+focus on the absorption spectrum of Rydberg excitons in cuprous oxide. The
+interplay of band edge and exciton levels is analyzed numerically, whereby the
+self-consistent solution is compared to the semiclassical Debye approximation.
+Our results provide criteria which allow to verify or rule out the different
+band edge models against future experimental data.",1906.10384v2
+2019-07-11,Percolation description of charge transport in amorphous oxide semiconductors,"The charge transport mechanism in amorphous oxide semiconductors (AOS) is a
+matter of controversial debates. Most theoretical studies so far neglected the
+percolation nature of the phenomenon. In this article, a recipe for theoretical
+description of charge transport in AOSs is formulated using the percolation
+arguments. Comparison with the previous theoretical studies shows a superiority
+of the percolation approach. The results of the percolation theory are compared
+to experimental data obtained in various InGaZnO materials revealing parameters
+of the disorder potential in such AOS.",1907.05107v1
+2019-07-11,Percolation description of charge transport in the random barrier model applied to amorphous oxide semiconductors,"Charge transport in amorphous oxide semiconductors is often described as the
+band transport affected by disorder in the form of random potential barriers
+(RB). Theoretical studies in the framework of this approach neglected so far
+the percolation nature of the phenomenon. In this article, a recipe for
+theoretical description of charge transport in the RB model is formulated using
+percolation arguments. Comparison with the results published so far evidences
+the superiority of the percolation approach.",1907.05113v2
+2019-10-16,Boron doping in gallium oxide from first principles,"We study the feasibility of boron doping in gallium oxide
+($\text{Ga}_2\text{O}_3$) for neutron detection. $\text{Ga}_2\text{O}_3$ is a
+wide band-gap, radiation hard material which has potential for neutron
+detection if it can be doped with a neutron active element. We investigate the
+boron-10 isotope as a possible neutron active dopant. Intrinsic and boron
+induced defects in $\text{Ga}_2\text{O}_3$ are studied with semi-local and
+hybrid density-functional-theory calculations. We find that in growth
+conditions favourable for boron, boron substitutional defects are likely to
+form making boron doping of $\text{Ga}_2\text{O}_3$ feasible.",1910.07371v2
+2020-04-02,Synthesis and $\textit{in-situ}$ characterization of photochromic yttrium oxyhydride grown by reactive $e^-$-beam evaporation,"We report on controlled growth of photochromic yttrium oxyhydride thin films
+monitored by $\textit{in-situ}$ composition depth profiling. Films were grown
+by reactive $e^-$-beam evaporation and subsequently oxidized, while
+simultaneously tracking the oxygen and hydrogen concentrations. Sample
+composition and photochromic response were characterized $\textit{in-situ}$
+using non destructive ion beam analysis and image analysis, respectively - as
+well as complementary $\textit{ex-situ}$ ion beam methods, X-ray diffraction
+and optical spectrophotometry. We show that photochromic yttrium oxyhydride can
+be grown as yttrium dihydride, which is then oxidized to O/H ratios triggering
+the photochromic response.",2004.01093v2
+2020-12-30,Carbon Nanomaterials to Combat Virus: A perspective in view of COVID-19,"The rapid outbreaks of lethal viruses necessitate the development of novel
+antiviral substance. Besides the conventional antiviral substances,
+biocompatible nanomaterials also have significant potential in combating the
+virus at various stages of infection. Carbon nanomaterials have an impressive
+record against viruses and can deal with many crucial healthcare issues. In
+accordance with the published literature, biocompatible carbon nanomaterials
+have a promising prospect as an antiviral substance. Subsequently, the
+antiviral properties of different carbon nanomaterials namely fullerene, carbon
+nanotube, carbon dot and graphene oxide have been reviewed.",2012.15101v1
+2021-01-12,From high-$T_c$ to low-$T_c$: Multi-orbital effects in transition metal oxides,"Despite the structural resemblance of certain cuprate and nickelate parent
+compounds there is a striking spread of $T_c$ among such transition metal oxide
+superconductors. We adopt a minimal two-orbital $e_g$ model which covers
+cuprates and nickelate heterostructures in different parametric limits, and
+analyse its superconducting instabilities. The joint consideration of
+interactions, doping, Fermiology, and in particular the $e_g$ orbital splitting
+allows us to explain the strongly differing pairing propensities in cuprate and
+nickelate superconductors.",2101.04689v1
+2021-01-28,Phonon Self-Energy Effects in Migdal-Eliashberg Theory,"Recent work on an electron-phonon model in two-dimensions is reviewed and
+some new results are presented. We utilize both Quantum Monte Carlo simulations
+and Migdal-Eliashberg theory. The type of electron-ion coupling considered is
+on-site. Competing instabilities are charge density wave (CDW) and singlet
+superconductivity. When the electron band is half-filled, the charge density
+wave dominates. Away from half-filling CDW correlations actually suppress
+superconductivity.",2101.12084v1
+2000-06-06,Normal-state pseudogap and electron flat dispersion in copper oxide materials,"The anomalous momentum and doping dependence of the electron spectral
+function and electron dispersion for copper oxide materials in the underdoped
+regime are studied within the t-J model. It is shown that the electron spectrum
+is changed with dopings, and the electron dispersion exhibits a flat band
+around ($\pi$,0) point in the Brillouin zone, which leads to the normal-state
+pseudogap formation. The theoretical results are consistent with the
+experiments and numerical simulations.",0006084v1
+2012-05-07,Junctionless dual-gate electrostatic modulation of self-aligned oxide channels by chitosan-based proton conductors,"Dual-gate electrostatic modulation gives an attractive approach for
+transistors performance improvement, threshold voltage (Vth) and operation mode
+modulation, which is favorable for chemical sensor and logic applications.
+Here, a self-aligned junctionless semiconducting oxide channels are dual-gate
+electrostatic modulated by solution-processed chitosan-based proton conductors
+on paper substrates. The low-voltage junctionless paper transistors can be
+effectively tuned from depletion mode to enhancement mode by the second
+in-plane gate. OR logic gate was experimentally demonstrated on such
+dual-in-plane gate junctionless transistors. Such dual-gate organic/inorganic
+hybrid paper transistors are promising for portable paper electronics.",1205.1309v1
+2012-05-24,The polarizability model for ferroelectricity in perovskite oxides,"This article reviews the polarizability model and its applications to
+ferroelectric perovskite oxides. The motivation for the introduction of the
+model is discussed and nonlinear oxygen ion polarizability effects and their
+lattice dynamical implementation outlined. While a large part of this work is
+dedicated to results obtained within the self-consistent-phonon approximation
+(SPA), also nonlinear solutions of the model are handled which are of interest
+to the physics of relaxor ferroelectrics, domain wall motions, incommensurate
+phase transitions. The main emphasis is to compare the results of the model
+with experimental data and to predict novel phenomena.",1205.5377v1
+2017-05-16,Defects and oxidation resilience in $InSe$,"We use density functional theory to study intrinsic defects and oxygen
+related defects in indium selenide. We find that ${InSe}$ is prone to
+oxidation, but however not reacting with oxygen as strongly as phosphorene. The
+dominant intrinsic defects in ${In}$-rich material are the ${In}$ interstitial,
+a shallow donor, and the ${Se}$ vacancy, which introduces deep traps. The
+latter can be passivated by oxygen, which is isoelectronic with ${Se}$. The
+dominant intrinsic defects in ${Se}$-rich material have comparatively higher
+formation energies.",1705.05519v2
+2017-11-27,On femtosecond laser shock peening of stainless steel AISI 316,"In this paper we report on the competition in metal surface hardening between
+the femtosecond shock peening on the one hand, and formation of laser-induced
+periodic surface structures (LIPSS) and surface oxidation on the other hand.
+Peening of the stainless steel AISI 316 due to shock loading induced by
+femtosecond laser ablation was successfully demonstrated. However, for some
+range of processing parameters, surface erosion due to LIPSS and oxidation seem
+to dominate over the peening effect. Strategies to increase the peening
+efficiency are discussed.",1711.09868v1
+2018-05-31,Auxiliary-field quantum Monte Carlo calculations of the structural properties of nickel oxide,"Auxiliary-field quantum Monte Carlo (AFQMC) has repeatedly demonstrated
+itself as one of the most accurate quantum many-body methods, capable of
+simulating both real and model systems. In this article we investigate the
+application of AFQMC to realistic strongly correlated materials in periodic
+Gaussian basis sets. Using nickel oxide (NiO) as an example, we investigate the
+importance of finite size effects and basis set errors on the structural
+properties of the correlated solid. We provide benchmark calculations for NiO
+and compare our results to both experiment measurements and existing
+theoretical methods. (LLNL-JRNL-752156)",1806.00122v1
+2018-08-15,Femtosecond laser crystallization of amorphous titanium oxide thin films,"In this paper we demonstrate experimentally that crystalline phases appear in
+amorphous titanium oxide upon processing with ultrafast laser pulses. Amorphous
+titanium thin films were produced by plasma-enhanced chemical vapor deposition
+(PECVD) and exposed to femtosecond laser pulses. Formation of rutile phase was
+confirmed by X-ray diffraction, Raman measurements and electron backscattering
+diffraction. A rang of processing parameters for the crystallization is
+reported and possible background mechanisms are discussed.",1808.05061v1
+2019-02-13,Static and Dynamic Oxide-Trapped-Charge-Induced Variability in Nanoscale CMOS Circuits,"The inter-device mismatch and intra-device temporal instability in the
+nanoscale CMOS circuits is examined from a unified point of view as a static
+and dynamic parts of the variability con-cerned with stochastic oxide charge
+trapping and de-trapping. This approach has been benchmarked on the recent
+evidence of the radiation-induced increase of inter-transistor mismatch in 60
+nm ICs. A possible reliability limitation in ultrascale circuits concerned with
+the single or a few charged defect instability is pointed out and estimated.",1902.04974v2
+2019-02-25,Environmental Remediation Applications of Carbon Nanotube and Graphene Oxide: Adsorption and Catalysis,"Environmental issues such as the wastewater have influenced each aspect of
+our lives. Coupling the existing remediation solutions with exploring new
+functional carbon nanomaterials (e.g. carbon nanotube, graphene oxide,
+graphene) by various perspectives shall open up a new venue to understand the
+environmental issues, phenomenon and find out the ways to get along with the
+nature. This review makes an attempt to provide an overview of potential
+environmental remediation solutions to the diverse challenges happening by
+using low-dimensional carbon nanomaterials and their composites as adsorbents,
+catalysts or catalysts support towards for the social sustainability.",1903.00468v1
+2019-03-20,Molecular beam epitaxy growth of superconducting Sr2RuO4 films,"We report growth of superconducting Sr2RuO4 films by oxide molecular beam
+epitaxy (MBE). Careful tuning of the Ru flux with an electron beam evaporator
+enables us to optimize growth conditions including the Ru/Sr flux ratio and
+also to investigate stoichiometry effects on the structural and transport
+properties. The highest onset transition temperature of about 1.1 K is observed
+for films grown in a slightly Ru-rich flux condition in order to suppress Ru
+deficiency. The realization of superconducting Sr2RuO4 films via oxide MBE
+opens up a new route to study the unconventional superconductivity of this
+material.",1903.08629v1
+2019-04-26,Anti-Localization in Oxides: Effective Spin-3/2 Model,"Weak anti-localization offers an experimental tool to address spin--orbit
+coupling of two-dimensional oxide surfaces and interfaces via
+magneto-transport. To overcome the shortcomings of the formulation for
+single-band spin-1/2 electrons, we consider an effective three-band model that
+allows a decomposition into a pseudo-spin representation 1/2+3/2. Whereas the
+well-established spin-1/2 transport signature results from the singlet and
+triplet sectors in the Cooperon equation, a new structure originates from the
+quintet and septet sectors generated by the spin 3/2x3/2 representation.",1904.11770v1
+2019-11-16,Multilayer plasmonic photonic structures embedding photochromic molecules or optical gain molecules,"We design photonic structures embedding different functional molecular
+systems of photochromic switching and lasing. We study the light absorption of
+two photochromic molecules and of 4,4'-bis[(N-carbazole)styryl]biphenyl
+(BSB-Cz) with density functional theory. For the photochromic diarylethene we
+derivate the refractive index with Kramers-Kronig relations and we design
+multilayer photonic structures alternating diarylethene with either poly vinyl
+carbazole or fluorine indium co-doped cadmium oxide (FICO) nanoparticlebased
+layers. For BSB-Cz we design a one-dimensional photonic crystal alternating
+BSB-Cz layers with $SiO_{2}$ layers and a microcavity embedding BSB-Cz between
+indium tin oxide (ITO) / FICO nanoparticle-based multilayers.",1911.07070v1
+2019-11-22,Nonlinear optical conductance from photon-assisted tunneling in a nanoantenna-coupled tunnel diode,"Ultrafast photon-assisted tunneling is shown to lead to large nonlinear
+dynamic currents that can be used to generate dc rectified current as well as
+higher order harmonic response from a metasurface-coupled tunnel diode. This
+artificial nonlinear media can have tailored resonances in the infrared around
+the longitudinal optical phonon modes of various compatible restrahlen oxides
+leading to enhanced electric field confinement in a metal-oxide-semiconductor
+tunnel diode. This provides a new avenue for the examination and design of
+nonlinear phenomena extending the concept of nonlinear susceptibility to
+nonlinear conductance and the dynamic current in these devices.",1911.10080v1
+2020-03-18,Interaction of charged impurities and Rydberg excitons in cuprous oxide,"We investigate the influence of a static, uncorrelated distribution of
+charged impurities on the spectrum of bound excitons in the copper oxide
+Cu$_{\text{2}}$O. We show that the statistical distribution of Stark shifts and
+ionisation rates leads to the vanishing of Rydberg resonances into an apparent
+continuum. The appearance of additional absorption lines due to the broken
+rotational symmetry, together with spatially inhomogeneous Stark shifts, leads
+to a modification of the observed line shapes that agree qualitatively with the
+changes observed in the experiment.",2003.08115v2
+2020-06-16,Enhanced Electromechanical Response in Defective Sm and Nd Co-doped Ceria,"Highly oxygen defective cerium oxide, e.g. Gd-doped ceria is a sustainable
+non-classical electrostrictor with electromechanical properties that are
+superior to lead-based piezoelectric metal oxides. Here, we report
+electrostriction in co-doped ceria (Sm, Nd) with a nominally low short-range
+vacancy-dopant association energy. Such a strategy results in a higher
+electrostrictive strain coefficient at lower-frequencies, and unexpected
+electromechanical strain saturation and relaxation effects. These outcomes
+support the hypothesis that electrostriction is strongly influenced by the
+local environment of oxygen vacancy and by the ionic migration blocking factors
+built-in the microstructure.",2006.09032v1
+2020-08-11,"On the stability and existence of nitro-graphene, nitro-graphane, and nitro-graphene oxide","Here, the possibility of the existence of nitro-graphene derivatives with
+undisturbed graphene backbone is considered. Based on the first-principles
+calculation, it is shown that while NO$_2$ is unable to form a covalent bond
+with bare graphene, it becomes possible in some structures of graphane,
+fluorographene, and graphene oxide. This paper presents, among others, an
+analysis of the surrounding influence on the C-NO$_2$ bond strength. The author
+believes, that potential prospects of these materials and discussion about
+possible synthesizing routes may help further research on graphene-based
+materials.",2008.04749v1
+2020-09-26,Improved Buildup Model for Radiation-Induced Defects in MOSFET Isolation Oxides,"Ionizing radiation induces defects in STI oxides in current MOSFETs. These
+defects may degrade the performance of the MOS circuit. Analytical models for
+the buildup of these defects during the radiation exposure are available in
+literature. In this paper, we show that the classical model used to estimate
+the buildup of TID-induced traps in MOSTs predicts inaccurate results at high
+radiation levels. We, further, introduce an improved model to estimate the
+buildup of defects that is valid for both low and high radiation doses. Our
+improved model is compared to published data showing its validity.",2009.12652v1
+2020-10-05,Resolving fast gas transients with Metal-Oxide sensors,"Electronic olfaction can help detect and localise harmful gases and
+pollutants, but the turbulence of natural environment presents a particular
+challenge: odor encounters are intermittent, and an effective electronic nose
+must therefore be able to resolve short odor pulses. The slow responses of the
+widely-used Metal-Oxide (MOX) gas sensors complicate the task. Here we combine
+high-resolution data acquisition with a processing method based on Kalman
+filtering and absolute-deadband sampling to extract fast transients. We find
+that our system can resolve the precise time of odor onset events, allowing
+direction estimation with a pair of MOX sensors in stereo-osmic configuration.",2010.01903v2
+2020-10-16,Trends in the valence band electronic structures of mixed uranium oxides,"Valence band electronic structure of mixed uranium oxides (UO2, U4O9, U3O7,
+U3O8, UO3) has been studied by the resonant inelastic X-ray scattering (RIXS)
+technique at the U M5 edge and by computational methods. We show here that the
+RIXS technique and recorded U 5f-O 2p charge transfer excitations can be used
+to proof the validity of theoretical approximations",2010.08301v1
+2021-05-27,Experimental validation of density functional theory calculations on the Zr/Al oxide nanocluster formation in bcc Fe,"Ab initio simulations carried out in different atomic cluster configurations
+in bcc Fe matrix containing Zr and Al suggest energetic favorability of Y-Zr-O
+phase nucleation, preferably with trigonal Y4Zr3O12 structure. Subsequently,
+the HRTEM investigation of the as-prepared Fe - 14 Cr-0.3 Y2O3 - 0.6 Zr - 4Al
+oxide dispersion strengthened (ODS) alloy shows 78% of precipitates with
+Y4Zr3O12 structure, thereby confirming the predictive power of ab initio
+simulations on the secondary formation in multi-component alloys.",2105.12963v2
+2021-06-30,Femtosecond LIPSS on indium-tin-oxide thin films at IR wavelengths,"We investigated laser-induced periodic surface structures (LIPSS) generated
+on indium-tin-oxide (ITO) thin films with femtosecond laser pulses in the
+infrared region. Using pulses between 1.6 and 2.4 ${\mu}$m central wavelength,
+we observed robust LIPSS morphologies with a periodicity close to
+${\lambda}$/10. Supporting finite-difference time-domain calculations suggest
+that the surface forms are rooted in the field localization in the surface pits
+leading to a periodically increased absorption of the laser pulse energy that
+creates the observed periodic structures.",2106.15999v4
+2021-08-23,Interseries dipole transitions from yellow to green excitons in cuprous oxide,"We study dipole interseries transitions between the yellow and green exciton
+series in cuprous oxide including the complex valence band structure. To this
+end, we extend previous studies of the spectrum of complex green exciton
+resonances [Phys. Rev. B 101, 075208 (2020)] to optical transitions between
+different exciton states in addition to transitions from the crystal ground
+state. This allows us to augment the calculations on interseries transitions
+using a hydrogen-like model [Phys. Rev. B 100, 085201 (2019)] by a more
+comprehensive treatment of the valence band structure.",2108.10441v1
+2021-09-19,Superionic states formation in group III oxides irradiated with ultrafast lasers,"A number of group III-metal oxides are studied via density functional theory
+in order to establish a possibility of nonthermal transition of these materials
+into a superionic state. Atomic and electronic properties of the materials are
+analyzed during the transitions to acquire insights into physical mechanisms
+guiding such transformations. This knowledge is then used to suggest a
+criterion allowing to predict the possibility of such transitions without
+employing computationally heavy methods.",2109.09084v1
+2022-06-30,"Doppler-free high resolution continuous wave optical UV-spectroscopy on the $\mathrm{A}\,^2Σ^+ \leftarrow \mathrm{X}\,^2Π_{3/2}$ transition in nitric oxide","We report on Doppler-free continuous-wave optical UV-spectroscopy resolving
+the hyperfine structure of the $\mathrm{A}\,^2\Sigma^+ \leftarrow
+\mathrm{X}\,^2\Pi_{3/2}$ transition in nitric oxide for total angular momenta
+$J_X=1.5-19.5$ on the $\mathrm{oP_{12ee}}$ branch. The resulting line
+splittings are compared to calculated splittings and fitted determining new
+values for the molecular constants $b, c, eQq_0$ and $b_F$ for the
+$\mathrm{A}\,^2\Sigma^+$ state. The constants are in good agreement with values
+previously determined by quantum beat spectroscopy.",2206.15243v1
+2022-08-17,The computational simulation of the reflection spectra of copper red glaze,"Owing to the limitation of traditional analytical methods, the coloration
+mechanism of copper red glaze has been disputed in the academic field for a
+long time, which mainly focuses on whether the color agent is metallic copper
+nanoparticles or cuprous oxide (Cu2O) nanoparticles. Based on Mie scattering
+theory, this work calculated the reflection spectra of nanoparticles uniformly
+dispersed in transparent glaze with different types, diameters and volume
+fractions, then discussed the differences between the reflection spectra of
+metallic copper and cuprous oxide as scatters, calculated the corresponding
+L*a*b* values, and compared them with the experimental results. This work
+provides a feasible and convenient method to distinguish these two coloration
+mechanisms.",2208.08043v1
+2022-09-20,Large Rashba parameter for 4d strongly correlated perovskite oxide SrNbO3 ultrathin films,"To elucidate the spin relaxation mechanism of SrNbO3 (SNO) ultrathin films,
+the transport properties of a series of SNO films with various thicknesses were
+measured on both sides of the metal insulator transition. The spin orbit
+scattering time was deduced from the analysis of the magnetoresistance with
+weak antilocalization theory, and it was found that the spin orbit scattering
+time was inversely proportional to the momentum scattering time. This result
+was explained in terms of the D`Yakonov Perel` mechanism, indicative of the
+dominant Rashba effect. The values of the Rashba parameter were largest in the
+values reported for other ultrathin films of metallic oxides.",2209.09730v1
+2022-10-19,Superlens with copper and copper oxide,"We investigate the imaging properties of copper-based superlens surrounded by
+copper oxide (Cu$_2$O). A subwavelength image resolution of the order
+$\lambda/9$ is demonstrated theoretically and verified in numerical
+simulations. It is shown that the existence of excitons in Cu$_2$O influence
+the static and dynamical optical properties of the lens. In particular, an
+improvement of image quality caused by absorption in the spectral region of
+excitonic resonances is investigated. The plasmon-exciton interaction in the
+system may pave the way to a tunable, highly nonlinear superlens designs.",2210.10376v1
+2022-11-08,Role of the annealing parameters on the resistance of indium tin oxide nanocrystalline films,"The optical and electrical properties of films made of nanoparticles of
+indium tin oxide (ITO) are widely studied because of the significance of this
+material for transparent electrodes, smart windows, and nonlinear optics
+components. In this work, a systematic study of the resistance in ITO
+nanocrystalline films, as a function of post-fabrication parameters, such as
+the temperature and time of annealing, has been performed. A tunability of the
+resistance with the annealing parameters, in a range of three orders of
+magnitude, has been demonstrated.",2211.04144v2
+2022-11-17,Nanoarchitectonics in fully printed perovskite solar cells with carbon-based electrodes,"A sacrificial film of polystyrene nanoparticles was utilized to introduce
+nano-cavities in mesoporous metal oxide layers. This enabled the growth of
+larger perovskite crystals inside the oxide scaffold with significantly
+suppressed non-radiative recombination and improving device performance. This
+work exemplifies potential applications of such nanoarchitectonic approaches in
+perovskite opto-electronic devices.",2211.09424v1
+2022-11-18,Acidity of graphene oxide aqueous solutions: the role of hydroxyls unveiled,"Nonempirical modeling of hydrated single-layer graphene oxide (GO) fragments
+revealed that at least one, but substantial origin of the acidity of aqueous GO
+solutions is the dissociation in closely grouped and favorably H-bonded
+hydroxyls. The process can further be promoted by the adjacent $\pi$-conjugated
+carbon segments at the edges of GO flakes or their inner defects. The apparent
+$pK_a$ values of the groups fall in a range of ca. 2.0 to 5.3. Under certain
+conditions the ionization may become spontaneous.",2211.10208v2
+2023-04-03,Synthesis parameter effect detection using quantitative representations and high dimensional distribution distances,"Detection of effects of the parameters of the synthetic process on the
+microstructure of materials is an important, yet elusive goal of materials
+science. We develop a method for detecting effects based on copula theory, high
+dimensional distribution distances, and permutational statistics to analyze a
+designed experiment synthesizing plutonium oxide from Pu(III) Oxalate. We
+detect effects of strike order and oxalic acid feed on the microstructure of
+the resulting plutonium oxide, which match the literature well. We also detect
+excess bivariate effects between the pairs of acid concentration, strike order
+and precipitation temperature.",2304.01120v1
+2023-04-26,Quantifying microstructure features for high performance solid oxide cells,"Focused ion beam (FIB)-scanning electron microscopy (SEM) allowed the
+characterization of the microstructure of two solid oxide fuel cells prepared
+at different sintering temperatures. 3D volume reconstruction showed that a
+relatively low sintering temperature significantly and positively affected
+distribution, volume and particle size of yttria-stabilized zirconia, nickel,
+and pore phases inside the anode, as well as the extent of the important
+triple-phase boundary interface.",2304.13572v1
+2023-04-26,K. Alex Müller and his important role in ferroelectricity,"In this review we concentrate on the work of K. Alex M\""uller in connection
+with his activities on oxide perovskites and ferroelectrics which were central
+to his research career long before he successfully discovered the first high
+temperature superconductor (HTSC) together with J. G. Bednorz in 1986. Not
+accidentally, but taking his long experience in perovskite ferroelectrics into
+account, the first HTSC was an oxide perovskite which had never been considered
+before to be superconducting.",2304.13642v1
+2023-04-16,Second-Order Non Linear Optical Properties of Zinc Oxide and Aluminum doped Zinc Oxide Thin Films grown by Atomic Layer deposition,"In this paper, Second-order NLO properties of ZnO and AZO thin films from
+experimental results are discussed. Measurements were a single wavelength of
+1.064 micrometers using the standard rotational Maker fringes technique in a
+transmission scheme. Further broadband dispersion of $\chi^{(2)}$ as
+characterized by harmonic generation over a broadband wavelength of 1.2-2.1
+micrometers are discussed. Experimental results for the p-and s-polarization of
+the fundamental beam are presented. In the analysis alpha-Quartz was used as
+the standard reference material. All the experiments were conducted at room
+temperature.",2304.14234v1
+2023-05-25,Excess noise in the anomalous metallic phase in amorphous indium oxide,"More than 25 years ago, unexpected metallic behavior was discovered on the
+superconducting side of the superconductor-to-insulator transition. To this
+day, the origin of this behavior is unclear. In this work, we present
+resistance and broadband voltage noise measurements in the kilohertz regime in
+amorphous indium oxide. We find that the metallic behavior gives rise to excess
+noise much larger than what is expected from thermal noise with an unexpected
+frequency and temperature dependence whose origin remains elusive.",2305.15931v1
+2023-07-05,Visible-Light Assisted Covalent Surface Functionalization of Reduced Graphene Oxide Nanosheets with Arylazo Sulfones,"We present an environmentally benign methodology for the covalent
+functionalization (arylation) of reduced graphene oxide (rGO) nanosheets with
+arylazo sulfones. A variety of tagged aryl units were conveniently accommodated
+at the rGO surface via visible light irradiation of suspensions of carbon
+nanostructured materials in aqueous media. Mild reaction conditions, absence of
+photosensitizers, functional group tolerance and high atomic fractions (XPS
+analysis) represent some of the salient features characterizing the present
+methodology. Control experiments for the mechanistic elucidation (Raman
+analysis) and chemical nanomanipulation of the tagged rGO surfaces are also
+reported.",2307.02353v1
+2023-07-31,Proximitized insulators from disordered superconductors,"We present an experimental study of bilayers of a disordered Ag metal layer
+close to the metal-insulator transition and an Indium Oxide film which is on
+the insulating side of the superconductor-insulator-transition. Our results
+show that superconducting fluctuations within the indium-oxide film, that
+proximitize the underlying metal layer, induce insulating rather than
+superconducting behavior. This is ascribed to suppression of density of states
+(due to the superconducting energy gap) for quasiparticles in the proximitized
+regions. Our results present a novel manifestation of the proximity effect
+phenomenon and provide important insight into the nature of the insulating
+phase of the disorder driven superconductor-insulator-transition.",2307.16602v1
+2023-07-31,Transparent conductive oxides and low loss nitride-rich silicon waveguides as building blocks for neuromorphic photonics,"Fully CMOS-compatible photonic memory holding devices hold a potential in a
+development of ultrafast artificial neural networks. Leveraging the benefits of
+photonics such as high-bandwidth, low latencies, low-energy interconnect and
+high speed they can overcome the existing limits of the electronic processing.
+To satisfy all these requirements a new photonic platform is proposed that
+combines low-loss nitride-rich silicon as a guide and low-loss transparent
+conductive oxides as an active material that can provide high nonlinearity and
+bistability under both electrical and optical signals.",2308.00178v1
+2023-08-11,Statistical Material Law Support for Room Temperature Superconductivity in the Lead Apatite System,"Quantum mechanics calculations of an electronic orbital coupling distribution
+of the new possible Room Temperature (RT) system of lead apatite Pb10(PO4)6O
+system show that the complex orbital coupling characteristics of the new system
+are similar to those of copper oxide and with multiple orbital interactions.
+The overall bandwidth is significantly larger than the current largest copper
+oxide system, which can also be compared to near RT high-pressure hydride
+systems. By applying a material dependence law relating overall bandwidth to
+superconducting critical temperature across various typical superconducting
+systems, we predict that the electronic structure of the new material can
+support achieving RT superconductivity in the condition of a flatter band.",2308.06349v1
+2023-09-11,Valley splitting by extended zone effective mass approximation incorporating strain in silicon,"Silicon metal-oxide-semiconductor field effect transistors (MOSFETs)
+fabricated on a SIMOX (001) substrate, which is a kind of silicon on insulator
+(SOI) substrate, that is annealed at high temperature for a long time are known
+to exhibit large valley splitting, but the origin of this splitting has long
+been unknown. Extended zone effective-mass approximation (EMA) predicts that
+strain significantly affects valley splitting. In this study, we analyzed
+valley splitting based on this theory and found that the shear strain along
+<110> of approximately 5% near the buried oxide (BOX) interface is a promising
+source for large valley splitting.",2309.05219v1
+2023-10-13,Pushing the limits of ab-initio-NEGF transport using efficient dissipative Mode-Space algorithms for realistic simulations of low-dimensional semiconductors including their oxide interfaces,"We investigate the trade-offs between accuracy and efficiency for several
+flavors of the dissipative mode-space NEGF algorithm with the self-consistent
+Born approximation for DFT Hamiltonians. Using these models, we then
+demonstrate the dissipative self-consistent DFT-NEGF simulations of realistic
+2D-material devices including their oxide interfaces with large slab dimensions
+(up to 1000 atoms) and up to several 100,000 atoms in the full device, pushing
+the limit of ab-initio transport.",2310.09029v1
+2024-01-04,Three-wave mixing experiments in indium-tin-oxide thin-films with no phase matching,"One challenge of using nonlinear optical phenomena for practical applications
+is the need to perform phase-matching. Recently, epsilon-near-zero materials
+have been shown to demonstrate strong optical nonlinearities, in addition to
+their other unique properties. As suggested by their name, the permittivity of
+the material is close to zero for a certain wavelength range. We demonstrate
+that this small permittivity allows for efficient three-wave mixing
+interactions to take place in indium-tin-oxide thin films without the need for
+phase matching the pump and signal beams. The efficiency of the second-order
+nonlinear interactions is characterized, and cascaded three-wave mixing is
+demonstrated.",2401.02492v1
+2024-01-29,Optimization of gadolinium oxide growth deposited on Si by high pressure sputtering,"High k gadolinium oxide thin layers were deposited on silicon by
+high-pressure sputtering (HPS). In order to optimize the properties for
+microelectronic applications, different deposition conditions were used. Ti
+(scavenger) and Pt (nonreactive) were e-beam evaporated to fabricate
+metal-insulator-semiconductor (MIS) devices. According to x-ray diffraction,
+x-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy,
+policrystaline stoichiometric Gd2O3 films were obtained by HPS. MIS with the
+dielctric deposited at higher pressures also present lower flatband voltage
+shifts in the C-V hysteris curves.",2401.16499v1
+1996-02-29,Hole photoproduction in insulating copper oxide,"Basing on t-J model we calculate the k-dependence of a single hole
+photoproduction probability for CuO2 plane at zero doping. We also discuss the
+radiation of spin-waves which can substantially deform the shape of
+photoemission spectra.",9602160v1
+1997-10-21,Momentum density of high Tc Copper Oxydes,"We discuss the work aimed at studying the momentum density of high Tc
+superconducting oxides using Compton profile and positron annihilation
+spectroscopies.",9710216v1
+1999-05-24,Density-functional theory study of the catalytic oxidation of CO over transition metal surfaces,"In recent years due to improvements in calculation methods and increased
+computer power, it has become possible to perform first-principles
+investigations for ``simple'' chemical reactions at surfaces. We have carried
+out such studies for the catalytic oxidation of CO at transition metal
+surfaces, in particular, at the ruthenium surface for which unusual behavior
+compared to other transition metal catalysts has been reported. High gas
+pressure catalytic reactor experiments have revealed that the reaction rate
+over Ru for oxidizing conditions is the highest of the transition metals
+considered -- in contrast, under ultra high vacuum conditions, the rate is by
+far the lowest. We find that important for understanding the pressure
+dependence of the reaction is the fact that Ru(0001) can support high
+concentrations of oxygen at the surface. Under these conditions, the O-metal
+bond is atypically weak compared to that at lower coverages. We have
+investigated a number of possible reaction pathways for CO oxidation for the
+conditions of high oxygen coverages, including scattering reactions of
+gas-phase CO at the oxygen covered surface (Eley-Rideal mechanism) as well as
+the Langmuir-Hinshelwood mechanism involving reaction between adsorbed CO
+molecules and O atoms.",9905341v1
+2000-04-17,In search for the vortex charge and the Cooper pair mass,"A novel experiment for determination of the charge related to vortices in
+thin superconducting film is proposed and a number of related experimental
+set-ups are also theoretically considered. The methods are based on the
+Torricelli-Bernoulli effect in superconductors and the phenomenology of the
+effect is briefly discussed. The vortex charge is expressed via the effective
+mass of the Cooper pairs, thus both parameters, inaccessible by now, could be
+simultaneously determined. The experiment would require layered
+metal-insulator-superconductor structures and standard electronics employed in
+kinetic measurements. The quality of the insulator-superconductor interface
+should be high enough as to allow for observation of electric field effects
+similar to those investigated in superconducting field-effect transistors. The
+development of layer-by-layer growth technology of oxide superconductors
+provides unique possibility for investigation of new fundamental effects in
+these materials. In particular, the structures necessary for determination of
+the vortex charge could be used to study the superconducting surface Hall
+effect, Bernoulli effect, the superfluid density, etc.. In conclusion, the
+systematic investigation of new effects in oxide superconductors is envisaged
+as an important part of the material science underlying the oxide electronics.",0004286v2
+2002-01-28,p-Type semiconducting properties in lithium-doped MgO single crystals,"The phenomenally large enhancement in conductivity observed when Li-doped MgO
+crystals are oxidized at elevated temperatures was investigated by dc and ac
+electrical measurements in the temperature interval 250-673 K. The
+concentration of ([Li]^{0}) centers (Li^{+} ions each with a trapped hole)
+resulting from oxidation was monitored by optical absorption measurements.
+  Both dc and ac experiments provide consistent values for the bulk resistance.
+The electricalconductivity of oxidized MgO:Li crystals increases linearly with
+the concentration of ([Li]^{0}) centers. The conductivity is thermally
+activated with an activation energy of (0.70 +/- 0.01) eV, which is independent
+of the ([Li]^{0}) content. The \textit{standard semiconducting} mechanism
+satisfactorily explains these results. Free holes are the main contribution to
+band conduction as they are trapped at or released from the ([Li]^{0})-acceptor
+centers.
+  In as-grown MgO:Li crystals, electrical current increases dramatically with
+time due to the formation of ([Li]^{0}) centers. The activation energy values
+between 1.3 and 0.7 eV are likely a combination of the activation energy for
+the creation of ([Li]^{0}) centers and the activation energy of ionization of
+these centers. Destruction of ([Li]^{0}) centers can be induced in oxidized
+crystals by application of an electric field due to Joule heating up to
+temperatures at which ([Li]^{0}) centers are not stable.",0201502v1
+2005-10-17,Syntheses of a heterogeneous catalysts using vapor phase self-assembly,"The first vapor phase self-assembled heterocatalytic structure on surface is
+build from cobalt 5,10,15,20 tetrakis (4-aminophenyl)-21H, 23H-porphine through
+imide bonds. This heterogeneous catalyst possesses essential thermal and
+temporal stability along with catalytic activity in oxidation processes of
+organic substrates.",0510453v1
+2006-03-03,Chain-driven superconductivity of copper oxide identified by nuclear resonance,This paper has been withdrawn by the author due to time-consuming revision.,0603067v2
+2006-07-14,"High-dielectric constant and wide band gap inverse silver oxide phases of the ordered ternary alloys of SiO$_{2}$, GeO$_{2}$ and SnO$_{2}$","High-dielectric constant and wide band gap oxides have important
+technological applications. The crystalline oxide polymorphs having lattice
+constant compatibility to silicon are particularly desirable. One recently
+reported candidate is the inverse silver oxide phase of SiO$_2$.
+First-principles study of this system together with its isovalent equivalents
+GeO$_{2}$, SnO$_{2}$ as well as their ternary alloys are performed. Within the
+framework of density functional theory both generalized gradient approximation
+and local density approximation (LDA) are employed to obtain their structural
+properties, elastic constants and the electronic band structures. To check the
+stability of these materials, phonon dispersion curves are computed which
+indicate that GeO$_{2}$ and SnO$_{2}$ have negative phonon branches whereas
+their ternary alloys Si$_{0.5}$Ge$_{0.5}$O$_{2}$, Si$_{0.5}$Sn$_{0.5}$O$_{2}$,
+and Ge$_{0.5}$Sn$_{0.5}$O$_{2}$ are all stable within LDA possessing dielectric
+constants ranging between 10 to 20. Furthermore, the lattice constant of
+Si$_{0.5}$Ge$_{0.5}$O$_{2}$ is virtually identical to the Si(100) surface. The
+$GW$ band gaps of the stable materials are computed which restore the wide band
+gap values in addition to their high dielectric constants.",0607353v2
+2003-09-25,Cosmological backgrounds of superstring theory and Solvable Algebras: Oxidation and Branes,"We develop a systematic algorithm to construct, classify and study exact
+solutions of type II A/B supergravity which are time--dependent and homogeneous
+and hence represent candidate cosmological backgrounds. Using the formalism of
+solvable Lie algebras to represent the geometry of non--compact coset manifolds
+U/H we are able to reduce the supergravity field equations to the geodesic
+equations in U/H and rephrase these latter in a completely algebraic setup by
+means of the so called Nomizu operator representation of covariant derivatives
+in solvable group manifolds. In this way a systematic method of integration of
+supergravity equations is provided. We show how the possible D=3 solutions are
+classified by non--compact subalgebras G of E8(8) and their ten--dimensional
+physical interpretation (oxidation) depends on the classification of the
+different embeddings of G inside E8(8). We give some preliminary examples of
+explicit solutions based on the simplest choice G=A2. We also show how, upon
+oxidation, these solutions provide a smooth and exact realization of the
+bouncing phenomenon on Weyl chamber walls envisaged by the cosmological
+billiards of Damour et al. We also show how this physical phenomenon is
+triggered by the presence of euclidean $D$--branes possibly interpretable at
+the microscopic level as S--branes. We outline how our analysis could be
+extended to a wider setup where, by further reducing to $D=2,1$, more general
+backgrounds could be constructed applying our method to the infinite algebras
+E9 and E10.",0309237v2
+2000-04-19,Structures and Stabilities of CaO and MgO Clusters and Cluster Ions: An alternative interpretation of the experimental mass spectra,"The structures and relative stabilities of doubly-charged nonstoichiometric
+(CaO)$_n$Ca$^{2+}$ (n=1--29) cluster ions and of neutral stoichiometric
+(MgO)$_n$ and (CaO)$_n$ (n=3,6,9,12,15,18) clusters are studied through {\em ab
+initio} Perturbed Ion plus polarization calculations. The large
+coordination-dependent polarizabilities of oxide anions favor the formation of
+surface sites, making the critical cluster size where anions with bulk
+coordination first appear larger than that found in the related case of alkali
+halides. Thus, we show that there are substantial structural differences
+between alkali halide and alkaline-earth oxide cluster ions, contrary to what
+is suggested by the similarities in the experimental mass spectra. An
+alternative interpretation of the magic numbers for the case of oxides is
+proposed, which involves an explicit consideration of isomer structures
+different from the ground states. A comparison with the previously studied
+(MgO)$_n$Mg$^{2+}$ cluster ions shows that the emergence of bulklike structural
+properties with size is slower for calcium oxide. Nevertheless, the structures
+of the doubly charged clusters are rather similar for the two materials. On the
+contrary, the study of the neutrals reveals interesting structural differences
+between MgO and CaO, similar to those found in the case of alkali halides.",0004041v4
+2007-06-14,The autoignition of cyclopentane and cyclohexane in a shock tube,"Ignition delay times of cyclohexane-oxygen-argon and
+cyclopentane-oxygen-argon mixtures have been measured in a shock tube, the
+onset of ignition being detected by OH radical emission. Mixtures contained 0.5
+or 1 % of hydrocarbon for equivalence ratios ranging from 0.5 to 2. Reflected
+shock waves allowed temperatures from 1230 to 1800 K and pressures from 7.3 to
+9.5 atm to be obtained. These measurements have shown that cyclopentane is much
+less reactive than cyclohexane, as for a given temperature the observed
+autoignition delay times were about ten times higher for the C5 compound
+compared to the C6. Detailed mechanisms for the combustion of cyclohexane and
+cyclopentane have been proposed to reproduce these results. The elementary
+steps included in the kinetic models of the oxidation of cyclanes are close to
+those proposed to describe the oxidation of acyclic alkanes and alkenes.
+Consequently, it has been possible to obtain these models by using an improved
+version of software EXGAS, a computer package developed to perform the
+automatic generation of detailed kinetic models for the gas-phase oxidation and
+combustion of linear and branched alkanes and alkenes. Nevertheless, the
+modelling of the oxidation of cyclanes requires to consider new types of
+generic reactions, and especially to define new correlations for the estimation
+of the rate constants. Ab initio calculations have been used to better know
+some of the rate constants used in the case of cyclopentane. The main reaction
+pathways have been derived from flow rate and sensitivity analyses.",0706.2060v1
+2007-08-03,Delayed treatment with nimesulide reduces measures of oxidative stress following global ischemic brain injury in gerbils,"Metabolism of arachidonic acid by cyclooxygenase is one of the primary
+sources of reactive oxygen species in the ischemic brain. Neuronal
+overexpression of cyclooxygenase-2 has recently been shown to contribute to
+neurodegeneration following ischemic injury. In the present study, we examined
+the possibility that the neuroprotective effects of the cyclooxygenase-2
+inhibitor nimesulide would depend upon reduction of oxidative stress following
+cerebral ischemia. Gerbils were subjected to 5 min of transient global cerebral
+ischemia followed by 48 h of reperfusion and markers of oxidative stress were
+measured in hippocampus of gerbils receiving vehicle or nimesulide treatment at
+three different clinically relevant doses (3, 6 or 12 mg/kg). Compared with
+vehicle, nimesulide significantly (P<0.05) reduced hippocampal glutathione
+depletion and lipid peroxidation, as assessed by the levels of malondialdehyde
+(MDA), 4-hydroxy-alkenals (4-HDA) and lipid hydroperoxides levels, even when
+the treatment was delayed until 6 h after ischemia. Biochemical evidences of
+nimesulide neuroprotection were supported by histofluorescence findings using
+the novel marker of neuronal degeneration Fluoro-Jade B. Few Fluoro-Jade B
+positive cells were seen in CA1 region of hippocampus in ischemic animals
+treated with nimesulide compared with vehicle. These results suggest that
+nimesulide may protect neurons by attenuating oxidative stress and reperfusion
+injury following the ischemic insult with a wide therapeutic window of
+protection.",0708.0559v1
+2007-08-15,Selective vulnerability to kainate-induced oxidative damage in different rat brain regions,"Some markers of oxidative injury were measured in different rat brain areas
+(hippocampus, cerebral cortex, striatum, hypothalamus, amygdala/piriform cortex
+and cerebellum) after the systemic administration of an excitotoxic dose of
+kainic acid (KA, 9 mg kg(-1) i.p.) at two different sampling times (24 and 48
+h). Kainic acid was able to lower markedly (P < 0.05) the glutathione (GSH)
+levels in hippocampus, cerebellum and amygdala/piriform cortex (maximal
+reduction at 24 h). In a similar way, lipid peroxidation, as assessed by
+malonaldehyde and 4-hydroxyalkenal levels, significantly increased (P < 0.05)
+in hippocampus, cerebellum and amygdala/piriform cortex mainly at 24 h after
+KA. In addition, hippocampal superoxide dismutase (SOD) activity decreased
+significantly (P < 0.05) with respect to basal levels by 24 h after KA
+application. On the other hand, brain areas such as hypothalamus, striatum and
+cerebral cortex seem to be less susceptible to KA excitotoxicity. According to
+these findings, the pattern of oxidative injury induced by systemically
+administered KA seems to be highly region-specific. Further, our results have
+shown that a lower antioxidant status (GSH and SOD) seems not to play an
+important role in the selective vulnerability of certain brain regions because
+it correlates poorly with increases in markers of oxidative damage.",0708.2061v1
+2007-10-09,Critical Oxide Thickness for Efficient Single-walled Carbon Nanotube Growth on Silicon Using Thin SiO2 Diffusion Barriers,"The ability to integrate carbon nanotubes, especially single-walled carbon
+nanotubes, seamlessly onto silicon would expand the range of applications
+considerably. Though direct integration using chemical vapor deposition is the
+simplest method, the growth of single-walled carbon nanotubes on bare silicon
+and on ultra-thin oxides is greatly inhibited due to the formation of a
+non-catalytic silicide. Using x-ray photoelectron spectroscopy, we show that
+silicide formation occurs on ultra-thin oxides due to thermally activated metal
+diffusion through the oxide. Silicides affect the growth of single-walled
+nanotubes more than multi-walled nanotubes due to the increased kinetics at the
+higher single-walled nanotube growth temperature. We demonstrate that nickel
+and iron catalysts, when deposited on clean silicon or ultra-thin silicon
+dioxide layers, begin to form silicides at relatively low temperatures, and
+that by 900C, all of the catalyst has been incorporated into the silicide,
+rendering it inactive for subsequent single-walled nanotube growth. We further
+show that a 4 nm silicon dioxide layer is the minimum diffusion barrier
+thickness which allows for efficient single-walled nanotube growth.",0710.1769v1
+2008-04-21,Redispersible Hybrid Nanopowders: Cerium Oxide Nanoparticle Complexes with Phosphonated-PEG Oligomers,"Rare earth cerium oxide (ceria) nanoparticles are stabilized using
+end-functional phosphonated-PEG oligomers. The complexation process and
+structure of the resulting hybrid core-shell singlet nanocolloids are
+described, characterized and modeled using light and neutron scattering data.
+The adsorption mechanism is non-stoichiometric, yielding the number of adsorbed
+chains per particle Nads = 270 at saturation. Adsorption isotherms show a high
+affinity of the phosphonate head for the ceria surface (adsorption energy ~ -16
+kT) suggesting an electrostatic driving force for the complexation. The ease,
+efficiency and integrity of the complexation is highlighted by the formation of
+nanometric sized cerium oxide particles covered with a well anchored PEG layer,
+maintaining the characteristics of the original sol. This solvating brush-like
+layer is sufficient to solubilize the particles and greatly expand the
+stability range of the original sol up to pH = 9. We underscore two key
+attributes of the tailored sol: i) strong UV absorption capability after
+functionalization and ii) ability to re-disperse after freeze-drying as powder
+in aqueous or organic solvents in varying concentrations as singlet
+nanocolloids. This robust platform enables translation of intrinsic properties
+of mineral oxide nanoparticles to critical end use.",0804.3410v1
+2008-06-11,Detection of C3O in the low-mass protostar Elias 18,"We have performed new laboratory experiments which gave us the possibility to
+obtain an estimate of the amount of carbon chain oxides (namely C3O2, C2O, and
+C3O) formed after irradiation (with 200 keV protons) of pure CO ice, at 16 K.
+The analysis of laboratory data indicates that in dense molecular clouds, when
+high CO depletion occurs, an amount of carbon chain oxides as high as 2-3x10^-3
+with respect to gas phase carbon monoxide can be formed after ion irradiation
+of icy grain mantles. Then we have searched for gas phase C2O and C3O towards
+ten low-mass young stellar objects. Among these we have detected the C3O line
+at 38486.891 MHz towards the low-mass protostar Elias 18. On the basis of the
+laboratory results we suggest that in dense molecular clouds gas phase carbon
+chain oxides are formed in the solid phase after cosmic ion irradiation of
+CO-rich icy mantles and released to the gas phase after desorption of icy
+mantles. We expect that the Atacama Large Millimeter Array (ALMA), thanks to
+its high sensitivity and resolution, will increase the number of carbon chain
+oxides detected in dense molecular clouds.",0806.1830v1
+2008-12-10,An experimental and kinetic modelling study of the oxidation of the four isomers of butanol,"Butanol, an alcohol which can be produced from biomass sources, has received
+recent interest as an alternative to gasoline for use in spark ignition engines
+and as a possible blending compound with fossil diesel or biodiesel. Therefore,
+the autoignition of the four isomers of butanol (1-butanol, 2-butanol,
+iso-butanol, and tert-butanol) has been experimentally studied at high
+temperatures in a shock tube and a kinetic mechanism for description of their
+high-temperature oxidation has been developed. Ignition delay times for
+butanol/oxygen/argon mixtures have been measured behind reflected shock waves
+at temperatures and pressures ranging from approximately 1200 to 1800 K and 1
+to 4 bar. Electronically excited OH emission and pressure measurements were
+used to determine ignition delay times. A detailed kinetic mechanism has been
+developed to describe the oxidation of the butanol isomers and validated by
+comparison to the shock tube measurements. Reaction flux and sensitivity
+analysis indicate that the consumption of 1 butanol and iso-butanol, the most
+reactive isomers, takes place primarily by H-atom abstraction resulting in the
+formation of radicals, the decomposition of which yields highly reactive
+branching agents, H-atoms and OH radicals. Conversely, the consumption of tert
+butanol and 2-butanol, the least reactive isomers, takes place primarily via
+dehydration, resulting in the formation of alkenes, which lead to resonance
+stabilized radicals with very low reactivity. To our knowledge, the ignition
+delay measurements and oxidation mechanism presented here for 2-butanol,
+iso-butanol, and tert butanol are the first of their kind..",0812.1874v1
+2009-04-23,Purification and Characterization of an Arene cis-Dihydrodiol Dehydrogenase Endowed with Broad Substrate Specificity toward Polycyclic Aromatic Hydrocarbon Dihydrodiols,"Initial reactions involved in the bacterial degradation of polycyclic
+aromatic hydrocarbons (PAHs) include a ring-dihydroxylation catalyzed by a
+dioxygenase and a subsequent oxidation of the dihydrodiol products by a
+dehydrogenase. In this study, the dihydrodiol dehydrogenase from the
+PAH-degrading Sphingomonas strain CHY-1 has been characterized. The bphB gene
+encoding PAH dihydrodiol dehydrogenase (PDDH) was cloned and overexpressed as a
+His-tagged protein. The recombinant protein was purified as a homotetramer with
+an apparent Mr of 110,000. PDDH oxidized the cis-dihydrodiols derived from
+biphenyl and eight polycyclic hydrocarbons, including chrysene,
+benz[a]anthracene, and benzo[a]pyene, to corresponding catechols. Remarkably,
+the enzyme oxidized pyrene 4,5-dihydrodiol, whereas pyrene is not metabolized
+by strain CHY-1. The PAH catechols produced by PDDH rapidly auto-oxidized in
+air but were regenerated upon reaction of the o-quinones formed with NADH.
+Kinetic analyses performed under anoxic conditions revealed that the enzyme
+efficiently utilized two- to four-ring dihydrodiols, with Km values in the
+range of 1.4 to 7.1 $\mu$M, and exhibited a much higher Michaelis constant for
+NAD+ (Km of 160 $\mu$M). At pH 7.0, the specificity constant ranged from (1.3
+$\pm$ 0.1) x 106 M?1 s?1 with benz[a]anthracene 1,2-dihydrodiol to (20.0 $\pm$
+0.8) x 106 M?1 s?1 with naphthalene 1,2-dihydrodiol. The catalytic activity of
+the enzyme was 13-fold higher at pH 9.5. PDDH was subjected to inhibition by
+NADH and by 3,4-dihydroxyphenanthrene, and the inhibition patterns suggested
+that the mechanism of the reaction was ordered Bi Bi. The regulation of PDDH
+activity appears as a means to prevent the accumulation of PAH catechols in
+bacterial cells.",0904.3616v1
+2009-06-18,Oxide tunnel junctions supporting a two-dimensional electron gas,"The discovery of a two-dimensional electron gas (2DEG) at the interface
+between insulating oxides has led to a well-deserved level of excitement due to
+possible applications as ""in-plane"" all-oxide nanoelectronics. Here we expand
+the range of possibilities to the realm of ""out-of-plane"" nanoelectronics by
+examining such all-oxide heterostructures as barriers in tunnel junctions. As
+an example system we perform first-principles electronic structure and
+transport calculations of a tunnel junction with a [SrTiO3]4/[LaO]1/[SrTiO3]4
+heterostructure tunneling barrier embedded between SrRuO3 electrodes. The
+presence of the LaO atomic layer induces the formation of a 2DEG within the
+tunneling barrier which acts as an extended defect perpendicular to the
+transport direction, providing a route for resonant tunneling. Our calculations
+demonstrate that the tunneling conductance in this system can be strongly
+enhanced compared to a pure SrTiO3 barrier due to resonant tunneling, but that
+lattice polarization effects play a significant role in determining this
+behavior. In addition we find that this resonant tunneling is highly selective
+of the orbital symmetry of the tunneling states due to the ""orbital
+polarization"" of the 2DEG. We also discuss how the properties of the 2DEG are
+affected by the presence of metal electrodes.",0906.3543v1
+2009-09-30,Redox functionality mediated by adsorbed oxygen on a Pd-oxide film over a Pd(100) thin structure: A first-principles study,"Stable oxygen sites on a PdO film over a Pd(100) thin structures with a
+(sqrt{5} times sqrt{5}) R27^circ surface-unit cell are determined using the
+first-principles electronic structure calculations with the generalized
+gradient approximation. The adsorbed monatomic oxygen goes to a site bridging
+two 2-fold-coordinated Pd atoms or to a site bridging a 2-fold-coordinated Pd
+atom and a 4-fold-coordinated Pd atom. Estimated reaction energies of CO
+oxidation by reduction of the oxidized PdO film and N_2O reduction mediated by
+oxidation of the PdO film are exothermic. Motion of the adsorbed oxygen atom
+between the two stable sites is evaluated using the nudged elastic band method,
+where an energy barrier for a translational motion of the adsorbed oxygen may
+become sim 0.45 eV, which is low enough to allow fluxionality of the surface
+oxygen at high temperatures. The oxygen fluxionality is allowed by existence of
+2-fold-coordinated Pd atoms on the PdO film, whose local structure has
+similarity to that of Pd catalysts for the Suzuki-Miyaura cross coupling.
+Although NO_x (including NO_2 and NO) reduction is not always catalyzed only by
+the PdO film, we conclude that there may happen continual redox reactions
+mediated by oxygen-adsorbed PdO films over a Pd surface structure, when the
+influx of NO_x and CO continues, and when the reaction cycle is kept on a
+well-designed oxygen surface.",0909.5477v1
+2010-02-11,Real-time observation of bond-by-bond interface formation during the oxidation of (111) Si,"Atomic-level structure of solids is typically determined by techniques such
+as X-ray and electron diffraction,1, 2, 3, 4 which are sensitive to atomic
+positions. It is hardly necessary to mention the impact that these techniques
+have had on almost every field of science. However, the bonds between atoms are
+critical for determining the overall structure. The dynamics of these bonds
+have been difficult to quantify. Here, we combine second-harmonic generation
+and the bond-charge model of nonlinear optics5, 6 to probe, in real time, the
+dynamics of bond-by-bond chemical changes during the oxidation of H-terminated
+(111)Si, a surface that has been well characterized by static methods. We thus
+demonstrate that our approach provides new information about this exhaustively
+studied system. For example, oxidation is activated by a surprisingly small
+applied macroscopic strain, and exhibits anisotropic kinetics with one of the
+three equivalent back-bonds of on-axis samples reacting differently from the
+other two. Anisotropic oxidation kinetics also leads to observed transient
+changes in bond directions. By comparing results for surfaces strained in
+different directions, we find that in-plane control of surface chemistry is
+possible. The use of nonlinear optics as a bond-specific characterization tool
+is readily adaptable for studying structural and chemical dynamics in many
+other condensed-matter systems.",1002.2263v2
+2010-06-18,"Polarons, free charge localisation and effective dielectric permittivity in oxides","This review will deal with several types of free charge localisation in
+oxides and their consequences on the effective dielectric spectra of such
+materials. The first one is the polaronic localisation at the unit cell scale
+on residual impurities in ferroelectric networks. The second one is the
+collective localisation of free charge at macroscopic interfaces like surfaces,
+electrodes and grain boundaries in ceramics. Polarons have been observed in
+many oxide perovskites mostly when cations having several stable electronic
+configurations are present. In manganites, the density of such polarons is so
+high as to drive a net lattice of interacting polarons. On the other hand, in
+ferroelectric materials like BaTiO3 and LiNbO3, the density of polarons is
+usually very small but they can influence strongly the macroscopic
+conductivity. The contribution of such polarons to the dielectric spectra of
+ferroelectric materials is described. Even residual impurities as for example
+Iron can induce well defined anomalies at very low temperatures. This is mostly
+resulting from the interaction between localised polarons and the highly
+polarisable ferroelectric network in which they are embedded. The case of such
+residual polarons in SrTiO3 will be described in more details, emphasizing the
+quantum polaron state at liquid helium temperatures. Recently, several
+non-ferroelectric oxides have been shown to display giant effective dielectric
+permittivity. It is first shown that the frequency/temperature behaviour of
+such parameters is very similar in very different compounds (donor doped
+BaTiO3, CaCu3Ti4O12, LuFe2O4,Li doped NiO,...). This similarity calls for a
+common origin of the giant dielectric permittivity in these compounds. A space
+charge localisation at macroscopic interfaces can be the key for such extremely
+high dielectric permittivity.",1006.3719v1
+2010-08-11,Defect engineering in oxide heterostructures by enhanced oxygen surface exchange,"The synthesis of materials with well-controlled composition and structure
+improves our understanding of their intrinsic electrical transport properties.
+Recent developments in atomically controlled growth have been shown to be
+crucial in enabling the study of new physical phenomena in epitaxial oxide
+heterostructures. Nevertheless, these phenomena can be influenced by the
+presence of defects that act as extrinsic sources of both doping and impurity
+scattering. Control over the nature and density of such defects is therefore
+necessary, are we to fully understand the intrinsic materials properties and
+exploit them in future device technologies. Here, we show that incorporation of
+a strontium copper oxide nano-layer strongly reduces the impurity scattering at
+conducting interfaces in oxide LaAlO3-SrTiO3(001) heterostructures, opening the
+door to high carrier mobility materials. We propose that this remote cuprate
+layer facilitates enhanced suppression of oxygen defects by reducing the
+kinetic barrier for oxygen exchange in the hetero-interfacial film system. This
+design concept of controlled defect engineering can be of significant
+importance in applications in which enhanced oxygen surface exchange plays a
+crucial role.",1008.1896v2
+2010-08-27,Large magnetoelectric effect in the Al1-xGaxFeO3 family of multiferroic Oxides,"AlFeO3, GaFeO3 and Al0.5Ga0.5FeO3, all crystallizing in a non-centrosymmetric
+space group, are multiferroic and also exhibit magnetoelectric properties, with
+Al0.5Ga0.5FeO3 showing unusually large magnetocapacitance at 300 K.",1008.4672v1
+2010-10-07,The route to high temperature superconductivity in transition metal oxides,"The discovery of high temperature superconductivity in cuprates was possible
+only through an intimate knowledge of perovskite oxides which have been
+synthesized and characterized for decades at the IBM in the Z\""urich
+laboratoty. Especially SrTiO3 and LaAlO3 have been in the focus at IBM as was
+presented in Volume 1 of a series [1]. Probably for the first time detailed
+microscopic investigations of the local properties of these compounds have been
+obtained by studying by means of EPR the surroundings of transition metal
+impurities in these materials. These experiments enabled the identification of
+the order parameter of the structural instability observed in these oxides.
+However, the idea to search for superconductivity came later motivated by
+theoretical considerations that metallic hydrogen could become superconducting
+at high temperatures. Since SrTiO3 is an insulator it was thought that the
+implantation of hydrogen would render it metallic and eventually also
+superconducting. This approach failed since the carrier density remained always
+too small. In sequence it was then tried to achieve a metallic state in oxide
+perovskites by varying their composition which was in so far promising as
+reduced SrTiO3 exhibits superconductivity at 0.3K [2]. Furthermore it was
+subsequently shown [3] that Tc can be enhanced to 1.2K by doping SrTiO3 with
+Nb. In spite of the fact that Tc was far below values achieved in A15
+compounds, a remarkable observation was connected with the Nb doped perovskite,
+namely for the first time long before predicted two-gap superconductivity was
+realized here.",1010.1377v1
+2011-06-19,Oxidation mechanism in metal nanoclusters: Zn nanoclusters to ZnO hollow nanoclusters,"Zn nanoclusters (NCs) are deposited by Low-energy cluster beam deposition
+technique. The mechanism of oxidation is studied by analysing their
+compositional and morphological evolution over a long span of time (three
+years) due to exposure to ambient atmosphere. It is concluded that the
+mechanism proceeds in two steps. In the first step, the shell of ZnO forms over
+Zn NCs rapidly up to certain limiting thickness: with in few days -- depending
+upon the size -- Zn NCs are converted to Zn-ZnO (core-shell), Zn-void-ZnO, or
+hollow ZnO type NCs. Bigger than ~15 nm become Zn-ZnO (core-shell) type: among
+them, NCs above ~25 nm could able to retain their initial geometrical shapes
+(namely triangular, hexagonal, rectangular and rhombohedral), but ~25 to 15 nm
+size NCs become irregular or distorted geometrical shapes. NCs between ~15 to 5
+nm become Zn-void-ZnO type, and smaller than ~5 nm become ZnO hollow sphere
+type i.e. ZnO hollow NCs. In the second step, all Zn-void-ZnO and Zn-ZnO
+(core-shell) structures are converted to hollow ZnO NCs in a slow and gradual
+process, and the mechanism of conversion proceeds through expansion in size by
+incorporating ZnO monomers inside the shell. The observed oxidation behaviour
+of NCs is compared with theory of Cabrera - Mott on low-temperature oxidation
+of metal.",1106.3752v2
+2011-07-08,Anchoring ceria nanoparticles on reduced graphene oxide and their electronic transport properties,This paper has been withdrawn.,1107.1745v2
+2011-08-23,Does H2O improve the catalytic activity of Au1-4/MgO towards CO oxidation?,"The present density functional theory study addresses the question whether
+the presence of H2O influences the catalytic activity of small gold clusters,
+Au1-4/MgO(100), towards the oxidation of carbon monoxide. To this end, we
+studied the (co-)adsorption of H2O and CO/O2 on these gold clusters. The ground
+state structures in the presence of all three molecular species, that we found,
+are Au1O2/MgO and Au2-4CO/MgO with H2O adsorbed on the surface in the proximity
+of the clusters-molecule complex. In this configuration the catalytic activity
+of Au1-4/MgO is indifferent to the presence of H2O. We also found that a
+stable, highly activated hydroperoxyl-hydroxyl complex, O2H\dot\dot OH, can be
+formed on Au1,3/MgO. For the catalytic active system Au8/MgO, it has been
+predicted that this complex opens an alternative catalytic reaction pathway
+towards CO oxidation. Our results suggest that this water mediated catalytic
+cycle is unlikely to occur on Au1,3/MgO. In the case of Au1/MgO the cycle is
+interrupted by the dissociation of the remaining (OH)2 complex after forming
+the first CO2 molecule. On Au3 /MgO the O2 H\dot\dot OH complex is likely to
+decompose upon the impact of a CO molecule, since three of its bond
+dissociation energies are comparable to the reaction barrier of the CO to CO2
+oxidation.",1108.4669v1
+2011-08-24,The effects of aggregation and protein corona on the cellular internalization of iron oxide nanoparticles,"Engineered inorganic nanoparticles are essential components in the
+development of nanotechnologies. For applications in nanomedicine, particles
+need to be functionalized to ensure a good dispersibility in biological fluids.
+In many cases however, functionalization is not sufficient : the particles
+become either coated by a corona of serum proteins or precipitate out of the
+solvent. In the present paper, we show that by changing the coating of iron
+oxide nanoparticles from a low-molecular weight ligand (citrate ions) to small
+carboxylated polymers (poly(acrylic acid)), the colloidal stability of the
+dispersion is improved and the adsorption/internalization of iron towards
+living mammalian cells is profoundly affected. Citrate-coated particles are
+shown to destabilize in all fetal-calf-serum based physiological conditions
+tested, whereas the polymer coated particles exhibit an outstanding
+dispersibility as well as a structure devoid of protein corona. The
+interactions between nanoparticles and human lymphoblastoid cells are
+investigated by transmission electron microscopy and flow cytometry. Two types
+of nanoparticle/cell interactions are underlined. Iron oxides are found either
+adsorbed on the cellular membranes, or internalized into membrane-bound
+endocytosis compartments. For the precipitating citrate-coated particles, the
+kinetics of interactions reveal a massive and rapid adsorption of iron oxide on
+the cell surfaces. The quantification of the partition between adsorbed and
+internalized iron was performed from the cytometry data. The results highlight
+the importance of resilient adsorbed nanomaterials at the cytoplasmic membrane.",1108.4779v1
+2011-08-30,Decomposition of formic acid,"Formic acid is known to act as a reduction agent for copper oxide. Its
+thermal uni-molecular decomposition was studied by means of DFT with special
+attention to reaction paths and kinetics.",1108.5891v1
+2012-02-02,Observation of reduction in Casimir force without change of dielectric permittivity,"Additional information is provided on the effect of the significant (up to
+35%) reduction in the magnitude of the Casimir force between an Au-coated
+sphere and an indium tin oxide film which was observed after UV treatment of
+the latter. A striking feature of this effect is that the reduction is not
+accompanied with a corresponding variation of the dielectric permittivity, as
+confirmed by direct ellipsometry measurements. The measurement data are
+compared with computations using the Lifshitz theory. It is shown that the data
+for the untreated sample are in a very good agreement with theory taking into
+account the free charge carriers in the indium tin oxide. The data for the
+UV-treated sample exclude the theoretical results obtained with account of free
+charge carriers. These data are found to be in a very good agreement with
+theory disregarding the free charge carriers in an indium tin oxide film. A
+possible theoretical explanation of our observations as a result of phase
+transition of indium tin oxide from metallic to dielectric state is discussed
+in comparison with other related experiments.",1202.0478v1
+2012-08-18,"Structural/microstructural, optical and electrical investigations of Sb-SnO2 thin films deposited by spray pyrolysis","The structural, optical and electrical properties of spray deposited antimony
+(Sb) doped tin oxide (SnO2) thin films, prepared from SnCl4 precursor, have
+been studied as a function of antimony doping concentration. The doping
+concentration was varied from 0 to 1.5 wt.% of Sb. The analysis of x-ray
+diffraction patterns revealed that the as deposited doped and undoped tin oxide
+thin films are pure crystalline tetragonal rutile phase of tin oxide which
+belongs to the space group P42/mnm (number 136). The surface morphological
+examination with field emission scanning electron microscopy (FESEM) revealed
+the fact that the grains are closely packed and pores/voids between the grains
+are very few. The transmittance spectra for as-deposited films were recorded in
+the wavelength range of 200 to 1000 nm. The transmittance of the films was
+observed to increase from 57% to 68% (at 800 nm) on initial addition of Sb (up
+to [Sb]/[Sn] = 0.5 wt.%) and then it is decreased for higher level of antimony
+doping ([Sb]/[Sn] > 0.5 wt.%). The sheet resistance of tin oxide films was
+found to decrease from 48 \Omega/sq for undoped films to 8 \Omega/sq for
+antimony doped films.",1208.4094v1
+2012-09-12,Modelling of c-C2H4O formation on grain surfaces,"Despite its potential reactivity due to ring strain, ethylene oxide (c-C2H4O)
+is a complex molecule that seems to be stable under the physical conditions of
+an interstellar dense core; indeed it has been detected towards several
+high-mass star forming regions with a column density of the order of 10e13cm-2
+(Ikeda et al. 2001). To date, its observational abundances cannot be reproduced
+by chemical models and this may be due to the significant contribution played
+by its chemistry on grain surfaces. Recently, Ward and Price (2011) have
+performed experiments in order to investigate the surface formation of ethylene
+oxide starting with oxygen atoms and ethylene ice as reactants. We present a
+chemical model which includes the most recent experimental results from Ward
+and Price (2011) on the formation of c-C2H4O. We study the influence of the
+physical parameters of dense cores on the abundances of c-C2H4O. We verify that
+ethylene oxide can indeed be formed during the cold phase (when the ISM dense
+cores are formed), via addition of an oxygen atom across the C=C double bond of
+the ethylene molecule, and released by thermal desorption during the hot core
+phase. A qualitative comparison between our theoretical results and those from
+the observations shows that we are able to reproduce the abundances of ethylene
+oxide towards high-mass star-forming regions.",1209.2540v1
+2012-10-06,Atomic layer engineering of perovskite oxides for chemically sharp heterointerfaces,"Advances in synthesis techniques and materials understanding have given rise
+to oxide heterostructures with intriguing physical phenomena that cannot be
+found in their constituents. In these structures, precise control of interface
+quality, including oxygen stoichiometry, is critical for unambiguous tailoring
+of the interfacial properties, with deposition of the first monolayer being the
+most important step in shaping a well-defined functional interface. Here, we
+studied interface formation and strain evolution during the initial growth of
+LaAlO3 on SrTiO3 by pulsed laser deposition, in search of a means for
+controlling the atomic-sharpness of the interfaces. Our experimental results
+show that growth of LaAlO3 at a high oxygen pressure dramatically enhances
+interface abruptness. As a consequence, the critical thickness for strain
+relaxation was increased, facilitating coherent epitaxy of perovskite oxides.
+This provides a clear understanding of the role of oxygen pressure during the
+interface formation, and enables the synthesis of oxide heterostructures with
+chemically-sharper interfaces.",1210.2007v1
+2012-10-25,Photochemistry in Terrestrial Exoplanet Atmospheres I: Photochemistry Model and Benchmark Cases,"We present a comprehensive photochemistry model for exploration of the
+chemical composition of terrestrial exoplanet atmospheres. The photochemistry
+model is designed from the ground up to have the capacity to treat all types of
+terrestrial planet atmospheres, ranging from oxidizing through reducing, which
+makes the code suitable for applications for the wide range of anticipated
+terrestrial exoplanet compositions. The one-dimensional chemical transport
+model treats up to 800 chemical reactions, photochemical processes, dry and wet
+deposition, surface emission and thermal escape of O, H, C, N and S bearing
+species, as well as formation and deposition of elemental sulfur and sulfuric
+acid aerosols. We validate the model by computing the atmospheric composition
+of current Earth and Mars and find agreement with observations of major trace
+gases in Earth's and Mars' atmospheres. We simulate several plausible
+atmospheric scenarios of terrestrial exoplanets, and choose three benchmark
+cases for atmospheres from reducing to oxidizing. The most interesting finding
+is that atomic hydrogen is always a more abundant reactive radical than the
+hydroxyl radical in anoxic atmospheres. Whether atomic hydrogen is the most
+important removal path for a molecule of interest also depends on the relevant
+reaction rates. We also find that volcanic carbon compounds (i.e., CH4 and CO2)
+are chemically long-lived and tend to be well mixed in both reducing and
+oxidizing atmospheres, and their dry deposition velocities to the surface
+control the atmospheric oxidation states. Furthermore, we revisit whether
+photochemically produced oxygen can cause false positives for detecting
+oxygenic photosynthesis, and find that in 1-bar CO2-rich atmospheres oxygen and
+ozone may build up to levels that have been previously considered unique
+signatures of life, if there is no surface emission of reducing gases...",1210.6885v1
+2013-03-15,Chromium-doped silica optical fibres : influence of the core composition on the Cr oxidation states and crystal field,"We have made chromium-doped, silica-based preforms and optical fibres by
+Modified Chemical Vapour Deposition and have studied the influence of the
+chemical composition of the doped region on the Cr-oxidation states and the
+spectroscopic properties of the samples. Chromium, introduced initially as
+Cr3+, is partially or totally oxidized during the fabrication process, and is
+stabilized in the core of the preforms and fibres as Cr3+ in octahedral
+coordination, and/or as Cr4+ in distorded tetrahedral coordination (Cs). Small
+concentrations (~1-2 mol%) of codopants in silica, such as germanium or
+aluminium, suffice to promote a particular oxidation state. Particularly, 1 mol
+% of aluminium stabilizes all present chromium into Cr4+. The ligand field
+parameters, Dq, B and Dq/B, for Cr3+ and Cr4+ are derived. It is shown that the
+chromium ions in our samples are in low to intermediate ligand field and that
+Dq and Dq/B decrease when the aluminium content increases. The absorption cross
+sections of Cr3+ are similar to that reported in glasses and crystals, whereas
+Cr4+ has lower values than reference laser materials.",1303.3835v1
+2013-04-05,Optical constants of refractory oxides at high temperatures,"Many cosmic dust species, among them refractory oxides, form at temperatures
+higher than 300 K. Nevertheless, most astrophysical studies are based on the
+room-temperature optical constants of solids, such as corundum and spinel. A
+more realistic approach is needed for these materials, especially in the
+context of modeling late-type stars. We aimed at deriving sets of optical
+constants of selected, astrophysically relevant oxide dust species with high
+melting points. A high-temperature-high-pressure-cell and a Fourier-transform
+spectrometer were used to measure reflectance spectra of polished samples. For
+corundum (alpha-Al$_2$O$_3$), spinel (MgAl$_2$O$_4$), and alpha-quartz
+(SiO$_2$), temperature-dependent optical constants were measured from 300 K up
+to more than 900 K. Small particle spectra were also calculated from these
+data. All three examined oxides show a significant temperature dependence of
+their mid-IR bands. For the case of corundum, we find that the 13$\mu$m
+emission feature - seen in the IR spectra of many AGB stars - can very well be
+assigned to this mineral species. The best fit of the feature is achieved with
+oblate corundum grains at mean temperatures around 550 K. Spinel remains a
+viable carrier of the 13$\mu$m feature as well, but only for T < 300 K and
+nearly spherical grain shapes. Under such circumstances, spinel grains may also
+account for the 31.8$\mu$m band that is frequently seen in sources of the
+13$\mu$m feature and which has not yet been identified with certainty.",1304.1717v1
+2013-06-21,Multi-orbital Cluster Perturbation Theory for transition metal oxides,"We present an extension of Cluster Perturbation Theory to include many body
+correlations associated to local e-e repulsion in real materials. We show that
+this approach can describe the physics of complex correlated materials where
+different atomic species and different orbitals coexist. The prototypical case
+of MnO is considered.",1306.5231v1
+2013-11-12,Influence of the C/O ratio on titanium and vanadium oxides in protoplanetary disks,"Context. The observation of carbon-rich disks have motivated several studies
+questioning the influence of the C/O ratio on their gas phase composition in
+order to establish the connection between the metallicity of hot-Jupiters and
+that of their parent stars.
+  Aims. We to propose a method that allows the characterization of the adopted
+C/O ratio in protoplanetary disks independently from the determination of the
+host star composition. Titanium and vanadium chemistries are investigated
+because they are strong optical absorbers and also because their oxides are
+known to be sensitive to the C/O ratio in some exoplanet atmospheres.
+  Methods. We use a commercial package based on the Gibbs energy minimization
+technique to compute the titanium and vanadium equilibrium chemistries in
+protoplanetary disks for C/O ratios ranging from 0.05 to 10. Our calculations
+are performed for pressures ranging from 1e-6 to 1e-2 bar, and for temperatures
+ranging from 50 to 2000 K.
+  Results. We find that the vanadium nitride/vanadium oxide and titanium
+hydride/titanium oxide gas phase ratios strongly depend on the C/O ratio in the
+hot parts of disks (T > 1000 K). Our calculations suggest that, in these
+regions, these ratios can be used as tracers of the C/O value in protoplanetary
+disks.",1311.2916v1
+2014-01-28,"Persistent metal-insulator transition at the surface of an oxygen-deficient, epitaxial manganite film","The oxygen stoichiometry has a large influence on the physical and chemical
+properties of complex oxides. Most of the functionality in e.g. catalysis and
+electrochemistry depends in particular on control of the oxygen stoichiometry.
+In order to understand the fundamental properties of intrinsic surfaces of
+oxygen-deficient complex oxides, we report on in situ temperature dependent
+scanning tunnelling spectroscopy experiments on pristine oxygen deficient,
+epitaxial manganite films. Although these films are insulating in subsequent ex
+situ in-plane electronic transport experiments at all temperatures, in situ
+scanning tunnelling spectroscopic data reveal that the surface of these films
+exhibits a metal-insulator transition (MIT) at 120 K, coincident with the onset
+of ferromagnetic ordering of small clusters in the bulk of the oxygen-deficient
+film. The surprising proximity of the surface MIT transition temperature of
+nonstoichiometric films with that of the fully oxygenated bulk suggests that
+the electronic properties in the surface region are not significantly affected
+by oxygen deficiency in the bulk. This carries important implications for the
+understanding and functional design of complex oxides and their interfaces with
+specific electronic properties for catalysis, oxide electronics and
+electrochemistry.",1401.7201v1
+2014-04-09,Melanin Made by Dopamine Oxidation: Thin Films and Interactions with Polyelectrolyte Multilayers,"The spontaneous oxidation of dopamine in slightly alkaline solutions was
+investigated on the basis of the work of Lee and others [Science, 318:426-430,
+2007], and the reaction product was identified as dopamine-melanin. The ability
+of melanin to covalently bind amine functional groups was confirmed by
+quantification of the corresponding binding sites on dopamine-melanin
+aggregates. Furthermore it is possible to redissolve dopamine-melanin
+aggregates in strongly alkaline solutions. The obtained small melanin grains
+were used to build layer-by-layer deposits with poly(diallyldimethylammonium).
+  Different methods of dopamine oxidation to grow melanin films at
+solid--liquid interfaces were developed. All examined methods lead to
+continuous dopamine-melanin films with very similar surface morphologies. The
+dopamine-melanin films become impermeable to electrochemical probes at a
+thickness in the 10 nm range. In this context a higher permeability for
+positively charged and neutral probes than for negatively charged ones was
+confirmed for one preparation method.
+  The adsorption of proteins on dopamine-melanin coatings was explained as
+combination of electrostatic and strong, most probably covalent, interactions.
+To obtain this explanation, the zeta-potential of dopamine-melanin deposits has
+been measured as a function of pH.
+  The formation of melanin by dopamine oxidation in layer-by-layer films of
+poly(L-lysine) (PLL) and hyaluronate (HA) was studied: Melanin is able to
+homogeneously fill $(\text{PLL-HA})_n$ films and the obtained
+polyelectrolyte-melanin composites can be detached from their substrate as
+free-standing membranes prepared by a biomimetic method in mild conditions.",1404.2408v1
+2014-07-10,Analysis of cellular responses of macrophages to zinc ions and zinc oxide nanoparticles: a combined targeted and proteomic approach,"Two different zinc oxide nanoparticles, as well as zinc ions, are used to
+study the cellular responses of the RAW 264 macrophage cell line. A proteomic
+screen is used to provide a wide view of the molecular effects of zinc, and the
+most prominent results are cross-validated by targeted studies. Furthermore,
+the alteration of important macrophage functions (e.g. phagocytosis) by zinc is
+also investigated. The intracellular dissolution/uptake of zinc is also studied
+to further characterize zinc toxicity. Zinc oxide nanoparticles dissolve
+readily in the cells, leading to high intracellular zinc concentrations, mostly
+as protein-bound zinc. The proteomic screen reveals a rather weak response in
+the oxidative stress response pathway, but a strong response both in the
+central metabolism and in the proteasomal protein degradation pathway. Targeted
+experiments confirm that carbohydrate catabolism and proteasome are critical
+determinants of sensitivity to zinc, which also induces DNA damage. Conversely,
+glutathione levels and phagocytosis appear unaffected at moderately toxic zinc
+concentrations.",1407.2732v1
+2014-07-28,Effect of Dielectric Properties of Ceramic-Solvent Interface on the Binding of Protein to Oxide Ceramics: a Non Local Electrostatic Approach,"The contribution of electrostatic interactions to the free energy of binding
+between model protein and a ceramic implant surface in the aqueous solvent,
+considered in the framework of the non-local electrostatic model, is calculated
+as a function of the implant low-frequency dielectric constant. We show that
+the existence of a dynamically ordered (low-dielectric) interfacial solvent
+layer at the protein-solvent and ceramic-solvent interface markedly increases
+charging energy of the protein and ceramic implant, and consequently makes the
+electrostatic contribution to the protein-ceramic binding energy more favorable
+(attractive). Our analysis shows that the corresponding electrostatic energy
+between protein and oxide ceramics depends non-monotonically on the dielectric
+constant of ceramic. Obtained results indicate that protein can attract
+electrostatically to the surface if ceramic material has a moderate dielectric
+constant below or about 35 (in particularly ZrO2 or Ta2O5). This is in contrast
+to classical (local) consideration of the solvent, which demonstrates an
+unfavorable electrostatic interaction of protein with typical metal oxide
+ceramic materials (dielectric constant>10). Thus, a solid implant coated by
+combining oxide ceramic with a reduced dielectric constant can be beneficial to
+strengthen the electrostatic binding of the protein-implant complex.",1407.7482v1
+2014-10-03,Topological nature and the multiple Dirac cones hidden in Bismuth high-Tc superconductors,"Recent theoretical studies employing density-functional theory have predicted
+BaBiO$_{3}$ (when doped with electrons) and YBiO$_{3}$ to become a topological
+insulator (TI) with a large topological gap (~ 0.7 eV). This, together with the
+natural stability against surface oxidation, makes the Bismuth-Oxide family of
+special interest for possible applications in quantum information and
+spintronics. The central question, we study here, is whether the hole-doped
+Bismuth Oxides, i.e. Ba$_{1-x}$K$_{x}$BiO$_{3}$ and
+BaPb$_{1-x}$Bi$_{x}$O$_{3}$, which are ""high-Tc"" bulk superconducting near 30
+K, additionally display in the further vicinity of their Fermi energy $E_{F}$ a
+topological gap with a Dirac-type of topological surface state. Our electronic
+structure calculations predict the K-doped family to emerge as a TI, with a
+topological gap above $E_{F}$. Thus, these compounds can become superconductors
+with hole-doping and potential TIs with additional electron doping.
+Furthermore, we predict the Bismuth-Oxide family to contain an additional Dirac
+cone below $E_{F}$ for further hole doping, which manifests these systems to be
+candidates for both electron- and hole-doped topological insulators.",1410.0821v2
+2015-01-07,A two-component flavin-dependent monooxygenase involved in actinorhodin biosynthesis in Streptomyces coelicolor,"The two-component flavin-dependent monooxygenases belong to an emerging class
+of enzymes involved in oxidation reactions in a number of metabolic and
+biosynthetic pathways in microorganisms. One component is a NAD(P)H:flavin
+oxidoreductase, which provides a reduced flavin to the second component, the
+proper monooxygenase. There, the reduced flavin activates molecular oxygen for
+substrate oxidation. Here, we study the flavin reductase ActVB and ActVA-ORF5
+gene product, both reported to be involved in the last step of biosynthesis of
+the natural antibiotic actinorhodin in Streptomyces coelicolor. For the first
+time we show that ActVA-ORF5 is a FMN-dependent monooxygenase that together
+with the help of the flavin reductase ActVB catalyzes the oxidation reaction.
+The mechanism of the transfer of reduced FMN between ActVB and ActVA-ORF5 has
+been investigated. Dissociation constant values for oxidized and reduced flavin
+(FMNox and FMNred) with regard to ActVB and ActVA-ORF5 have been determined.
+The data clearly demonstrate a thermodynamic transfer of FMNred from ActVB to
+ActVA-ORF5 without involving a particular interaction between the two protein
+components. In full agreement with these data, we propose a reaction mechanism
+in which FMNox binds to ActVB, where it is reduced, and the resulting FMNred
+moves to ActVA-ORF5, where it reacts with O2 to generate a flavinperoxide
+intermediate. A direct spectroscopic evidence for the formation of such species
+within ActVA-ORF5 is reported.",1501.01469v1
+2015-03-04,Boron Nitride Nanosheets for Metal Protection,"Although the high impermeability of graphene makes it an excellent barrier to
+inhibit metal oxidation and corrosion, graphene can form a galvanic cell with
+the underlying metal that promotes corrosion of the metal in the long term.
+Boron nitride (BN) nanosheets which have a similar impermeability could be a
+better choice as protective barrier, because they are more thermally and
+chemically stable than graphene and, more importantly, do not cause galvanic
+corrosion due to their electrical insulation. In this study, the performance of
+commercially available BN nanosheets grown by chemical vapor deposition as a
+protective coating on metal has been investigated. The heating of the copper
+foil covered with the BN nanosheet at 250 {\deg}C in air over 100 h results in
+dramatically less oxidation than the bare copper foil heated for 2 h under the
+same conditions. The electrochemical analyses reveal that the BN nanosheet
+coating can increase open circuit potential and possibly reduce oxidation of
+the underlying copper foil in sodium chloride solution. These results indicate
+that BN nanosheets are a good candidate for oxidation and corrosion protection,
+although conductive atomic force microscopy analyses show that the
+effectiveness of the protection relies on the quality of BN nanosheets.",1503.01295v1
+2015-03-04,Ligand-Hole in SnI6 Unit and Origin of Band Gap in Photovoltaic Perovskite Variant Cs2SnI6,"This paper has been published in Bulletin of the Chemical Society of Japan,
+which can be viewed at the following URL: http://doi.org/10.1246/bcsj.20150110
+  Cs2SnI6, a variant of perovskite CsSnI3, is expected for a photovoltaic
+material. Based on a simple ionic model, it is expected that Cs2SnI6 is
+composed of Cs+, I-, and Sn4+ ions and that the band gap is primarily made of
+occupied I- 5p6 valence band maximum (VBM) and unoccupied Sn4+ 5s conduction
+band minimum (CBM) similar to SnO2. In this work, we performed density
+functional theory (DFT) calculations and revealed that the real oxidation state
+of the Sn ion in Cs2SnI6 is +2 similar to CsSnI3. The +2 oxidation state of Sn
+originates from 2 ligand holes in the [SnI6]2- octahedron unit, where the
+ligand [I6] cluster has the apparent [I66-L+2]4- oxidation state, because the
+band gap is formed mainly by occupied I 5p VBM and unoccupied I 5p CBM. The +2
+oxidation state of Sn and the band gap are originated from the intracluster
+hybridization and stabilized by the strong covalent interaction between Sn and
+I.",1503.01458v3
+2015-04-20,Interface Engineering to Create a Strong Spin Filter Contact to Silicon,"Integrating epitaxial and ferromagnetic Europium Oxide (EuO) directly on
+silicon is a perfect route to enrich silicon nanotechnology with spin filter
+functionality.
+  To date, the inherent chemical reactivity between EuO and Si has prevented a
+heteroepitaxial integration without significant contaminations of the interface
+with Eu silicides and Si oxides.
+  We present a solution to this long-standing problem by applying two
+complementary passivation techniques for the reactive EuO/Si interface:
+  ($i$) an $in\:situ$ hydrogen-Si $(001)$ passivation and ($ii$) the
+application of oxygen-protective Eu monolayers --- without using any additional
+buffer layers.
+  By careful chemical depth profiling of the oxide-semiconductor interface via
+hard x-ray photoemission spectroscopy, we show how to systematically minimize
+both Eu silicide and Si oxide formation to the sub-monolayer regime --- and how
+to ultimately interface-engineer chemically clean, heteroepitaxial and
+ferromagnetic EuO/Si $(001)$ in order to create a strong spin filter contact to
+silicon.",1504.05108v4
+2015-06-24,"Mn$_3$O$_4$(001) film growth on Ag(001) - a systematic study using NEXAFS, STM, and LEED","The film growth of Mn$_3$O$_4$(001) films on Ag(001) up to film thicknesses
+of almost seven unit cells of Mn$_3$O$_4$ has been monitored using a
+complementary combination of near-edge X-ray absorption fine structure
+spectroscopy (NEXAFS), scanning tunneling microscopy (STM), and low-energy
+electron diffraction (LEED). The oxide films have been prepared by molecular
+beam epitaxy. Using NEXAFS, the identity of the Mn oxide has clearly been
+determined as Mn$_3$O$_4$. For the initial stages of growth, oxide islands with
+p(2$\times$1) and p(2$\times$2) structures are formed, which are embedded into
+the substrate. For Mn$_3$O$_4$ coverages up to 1.5 unit cells a p(2$\times$1)
+structure of the films is visible in STM and LEED. Further increase of the
+thickness leads to a phase transition of the oxide films resulting in an
+additional c(2$\times$2) structure with a 45$^\circ$ rotated atomic pattern.
+The emerging film structures are discussed on the basis of a sublayer model of
+the Mn$_3$O$_4$ spinel unit cell. While the polarity of the island edges
+determines the structure of initial islands, the surface energy of thicker
+layers is remarkably reduced by a film restructuring.",1506.07294v1
+2015-06-26,Fluorescence correlation spectroscopy in thin films at reflecting substrates as a means to study nanoscale structure and dynamics at soft-matter interfaces,"Structure and dynamics at soft-matter interfaces play an important role in
+nature and technical applications. Optical single-molecule investigations are
+non-invasive and capable to reveal heterogeneities at the nanoscale. In this
+work we develop an autocorrelation function (ACF) approach to retrieve tracer
+diffusion parameters obtained from fluorescence correlation spectroscopy (FCS)
+experiments in thin liquid films at reflecting substrates. This approach then
+is used to investigate structure and dynamics in 100 nm thick 8CB liquid
+crystal films on silicon wafers with five different oxide thicknesses. We find
+a different extension of the structural reorientation of 8CB at the
+solid-liquid interface for thin and for thick oxide. For the thin oxides, the
+perylenediimide tracer diffusion dynamics in general agrees with the
+hydrodynamic modeling using no-slip boundary conditions with only a small
+deviation close to the substrate, while a considerably stronger decrease of the
+interfacial tracer diffusion is found for the thick oxides.",1506.08129v4
+2015-08-27,Selective control of oxygen sublattice stability by epitaxial strain in Ruddlesden-Popper films,"Oxygen-defect control has long been considered an influential tuning knob for
+producing various property responses in complex oxide films. In addition to
+physical property changes, modification to the lattice structure, specifically
+lattice expansion, with increasing oxygen vacancy concentrations has been
+reported often and has become the convention for oxide materials. However, the
+current understanding of the lattice behavior in oxygen-deficient films becomes
+disputable when considering compounds containing different bonding environments
+or atomic layering. Moreover, tensile strain has recently been discovered to
+stabilize oxygen vacancies in epitaxial films, which further complicates the
+interpretation of lattice behavior resulting from their appearance. Here, we
+report on the selective strain control of oxygen vacancy formation and
+resulting lattice responses in the layered, Ruddlesden-Popper phases,
+La1.85Sr0.15CuO4. We found that a drastically reduced Gibbs free energy for
+oxygen vacancy formation near the typical growth temperature for
+tensile-strained epitaxial LSCO accounts for the large oxygen
+non-stoichiometry. Additionally, oxygen vacancies form preferentially in the
+equatorial position of the CuO2 plane, leading to a lattice contraction, rather
+than the expected expansion, observed with apical oxygen vacancies. Since
+oxygen stoichiometry plays a key role in determining the physical properties of
+many complex oxides, the strong strain coupling of oxygen nonstoichiometry and
+the unusual structural response reported here can provide new perspectives and
+understanding to the structure and property relationships of many other
+functional oxide materials.",1508.06971v1
+2016-02-17,Heart and diamond Fermi arcs in Pd and Pt oxide topological Dirac semimetals,"Topological Dirac semimetals (DSMs) exhibit nodal points through which energy
+bands disperse linearly in three-dimensional (3D) momentum space, a 3D analogue
+of graphene. The first experimentally confirmed DSMs with a pair of Dirac
+points (DPs), Na$_{3}$Bi and Cd$_{3}$As$_{2}$, show topological surface Fermi
+arc states and exotic magneto-transport properties, boosting the interest in
+the search for stable and nontoxic DSM materials. Here, based on the {\it
+ab-initio} band structure calculations we predict a family of palladium and
+platinum oxides as robust 3D DSMs. The novel topological properties of these
+compounds are distinct from all other previously reported DSMs, they are
+rendered by the multiple number of DPs in the compounds. We show that along
+three unit axes of the cubic lattice there exist three pairs of DPs, which are
+linked by Fermi arcs on the surface. The Fermi arcs display a Lifshitz
+transition from a heart- to a diamond-shape upon varying the chemical
+potential. Corresponding oxides are already available as high-quality single
+crystals, which is an excellent precondition for the verification of our
+prediction by photoemission and magneto-transport experiments. Our findings not
+only predict a number of much robust 3D DSM candidates but also extend DSMs to
+transition metal oxides, a versatile family of materials, which opens the door
+to investigate the interplay between DSMs and electronic correlations that is
+not possible in the previously discovered DSM materials.",1602.05533v1
+2016-03-13,"Influence of the ""second gap"" on the transparency-conductivity compromise in transparent conducting oxides: an ab initio study","Transparent conducting oxides (TCOs) are essential to many technologies.
+These materials are doped (\emph{n}- or \emph{p}-type) oxides with a large
+enough band gap (ideally $>$3~eV) to ensure transparency. However, the high
+carrier concentration present in TCOs lead additionally to the possibility for
+optical transitions from the occupied conduction bands to higher states for
+\emph{n}-type materials and from lower states to the unoccupied valence bands
+for \emph{p}-type TCOs. The ""second gap"" formed by these transitions might
+limit transparency and a large second gap has been sometimes proposed as a
+design criteria for high performance TCOs. Here, we study the influence of this
+second gap on optical absorption using \emph{ab initio} computations for
+several well-known \emph{n}- and \emph{p}-type TCOs. Our work demonstrates that
+most known \emph{n}-type TCOs do not suffer from second gap absorption in the
+visible even at very high carrier concentrations. On the contrary,
+\emph{p}-type oxides show lowering of their optical transmission for high
+carrier concentrations due to second gap effects. We link this dissimilarity to
+the different chemistries involved in \emph{n}- versus typical \emph{p}-type
+TCOs. Quantitatively, we show that second gap effects lead to only moderate
+loss of transmission (even in p-type TCOs) and suggest that a wide second gap,
+while beneficial, should not be considered as a needed criteria for a working
+TCO.",1603.04038v1
+2016-03-22,Polaronic contributions to oxidation and hole conductivity in acceptor-doped BaZrO$_3$,"Acceptor-doped perovskite oxides like BaZrO$_3$ are showing great potential
+as materials for renewable energy technologies where hydrogen acts an energy
+carrier, such as solid oxide fuel cells and hydrogen separation membranes.
+While ionic transport in these materials has been investigated intensively, the
+electronic counterpart has received much less attention and further exploration
+in this field is required. Here, we use density functional theory (DFT) to
+study hole polarons and their impact on hole conductivity in Y-doped BaZrO$_3$.
+Three different approaches have been used to remedy the self-interaction error
+of local and semi-local exchange-correlation functionals: DFT$+U$, pSIC-DFT and
+hybrid functionals. Self-trapped holes are found to be energetically favorable
+by about $-$0.1 eV and the presence of yttrium results in further
+stabilization. Polaron migration is predicted to occur through intraoctahedral
+transfer and polaron rotational processes, which are associated with adiabatic
+barriers of about 0.1 eV. However, the rather small energies associated with
+polaron formation and migration suggest that the hole becomes delocalized and
+band-like at elevated temperatures. These results together with an endothermic
+oxidation reaction [A. Lindman et al., Phys. Rev. B 91, 245114 (2015)] yield a
+picture that is consistent with experimental data for the hole conductivity.
+The results we present here provide new insight into hole transport in
+acceptor-doped BaZrO$_3$ and similar materials, which will be of value in the
+future development of sustainable technologies.",1603.06728v2
+2016-04-08,Detection of H2O and evidence for TiO/VO in an ultra hot exoplanet atmosphere,"We present a primary transit observation for the ultra hot (Teq~2400K) gas
+giant expolanet WASP-121b, made using the Hubble Space Telescope Wide Field
+Camera 3 in spectroscopic mode across the 1.12-1.64 micron wavelength range.
+The 1.4 micron water absorption band is detected at high confidence (5.4 sigma)
+in the planetary atmosphere. We also reanalyze ground-based photometric
+lightcurves taken in the B, r', and z' filters. Significantly deeper transits
+are measured in these optical bandpasses relative to the near-infrared
+wavelengths. We conclude that scattering by high-altitude haze alone is
+unlikely to account for this difference, and instead interpret it as evidence
+for titanium oxide and vanadium oxide absorption. Enhanced opacity is also
+inferred across the 1.12-1.3 micron wavelength range, possibly due to iron
+hydride absorption. If confirmed, WASP-121b will be the first exoplanet with
+titanium oxide, vanadium oxide, and iron hydride detected in transmission. The
+latter are important species in M/L dwarfs, and their presence is likely to
+have a significant effect on the overall physics and chemistry of the
+atmosphere, including the production of a strong thermal inversion.",1604.02310v1
+2016-06-18,Suppression of magnetoresistance in thin $WTe_2$ flakes by surface oxidation,"Recent renewed interest in layered transition metal dichalcogenides stems
+from the exotic electronic phases predicted and observed in the single- and
+few-layer limit. Realizing these electronic phases requires preserving the
+desired transport properties down to a monolayer, which is challenging. Here,
+using semimetallic $WTe_2$ that exhibits large magnetoresistance, we show that
+surface oxidation and Fermi level pinning degrade the transport properties of
+thin $WTe_2$ flakes significantly. With decreasing $WTe_2$ flake thickness, we
+observe a dramatic suppression of the large magnetoresistance. This is
+explained by fitting a two-band model to the transport data, which shows that
+mobility of the electron and hole carriers decreases significantly for thin
+flakes. The microscopic origin of this mobility decrease is attributed to a ~ 2
+nm-thick amorphous surface oxide layer that introduces disorder. The oxide
+layer also shifts the Fermi level by ~ 300 meV at the $WTe_2$ surface. However,
+band bending due to this Fermi level shift is not the dominant cause for the
+suppression of magnetoresistance as the electron and hole carrier densities are
+balanced down to ~ 13 nm based on the two-band model. Our study highlights the
+critical need to investigate often unanticipated and sometimes unavoidable
+extrinsic surface effects on the transport properties of layered
+dichalcogenides and other 2D materials.",1606.05756v1
+2016-09-02,"High pressure structural, elastic and vibrational properties of green energetic oxidizer ammonium dinitramide","Ammonium DiNitramide (ADN) is one of the most promising green energetic
+oxidizers for future rocket propellant formulations. In the present work, we
+report a detailed theoretical study on structural, elastic, and vibrational
+properties of the emerging oxidizer under hydrostatic compression using various
+dispersion correction methods to capture weak intermolecular (van der Waals and
+hydrogen bonding) interactions. The calculated ground state lattice parameters,
+axial compressibilities, and equation of state are in good accord with the
+available experimental results. Strength of intermolecular interactions has
+been correlated using the calculated compressibility curves and elastic moduli.
+Apart from this, we also observe discontinuities in the structural parameters
+and elastic constants as a function of pressure. Pictorial representation and
+quantification of intermolecular interactions are described by the 3D Hirshfeld
+surfaces and 2D finger print maps. In addition, the computed infra-red (IR)
+spectra at ambient pressure reveal that ADN is found to have more hygroscopic
+nature over Ammonium Perchlorate (AP) due to the presence of strong hydrogen
+bonding. Pressure dependent IR spectra show blue- and red-shift of bending and
+stretching frequencies which leads to weakening and strengthening of the
+hydrogen bonding below and above 5 GPa, respectively. The abrupt changes in the
+calculated structural, mechanical, and IR spectra suggest that ADN might
+undergo a first order structural transformation to a high pressure phase around
+5-6 GPa. From the predicted detonation properties, ADN is found to have high
+and low performance characteristics when compared with ammonium based energetic
+oxidizers and well-known secondary explosives, respectively.",1609.00472v1
+2017-03-20,In depth nano spectroscopic analysis on homogeneously switching double barrier memristive devices,"Memristors based on a double barrier design have been analysed by various
+nano spectroscopic methods to unveil details about its microstructure and
+conduction mechanism. The device consists of an AlOx tunnel barrier and a
+NbOy/Au Schottky barrier sandwiched between Nb bottom electrode and Au top
+electrode. As it was anticipated that the local chemical composition of the
+tunnel barrier, i.e. oxidation state of the metals as well as concentration and
+distribution of oxygen ions, have a major influence on electronic conduction,
+these factors were carefully analysed. A combined approach was chosen in order
+to reliably investigate electronic states of Nb and O by electron energy-loss
+spectroscopy as well as map elements whose transition edges exhibit a different
+energy range by energy-dispersive X-ray spectroscopy like Au and Al. The
+results conclusively demonstrate significant oxidation of the bottom electrode
+as well as a small oxygen vacancy concentration in the Al oxide tunnel barrier.
+Possible scenarios to explain this unexpected additional oxide layer are
+discussed and kinetic Monte Carlo simulations were applied in order to identify
+its influence on conduction mechanisms in the device. In light of the strong
+deviations between observed and originally sought layout, this study highlights
+the robustness in terms of structural deviations of the double barrier
+memristor device.",1703.06741v1
+2018-02-15,Achieving Direct Electrochemical Oxidation of Carbon below 600oC through a Novel Direct Carbon Fuel Cell,"Direct carbon fuel cells (DCFCs) are highly efficient power generators fueled
+by abundant and cheap solid carbons. However, the limited formation of triple
+phase boundaries (TPBs) within fuel electrodes inhibits their performance even
+at high temperatures due to the limitation of mass transfer. It also results in
+low direct-utilization of the fuel. To address the challenges of low carbon
+oxidation activity and low carbon utilization simultaneously, a highly
+efficient, 3-D solid-state architected anode has been developed to enhance the
+performance of DCFCs below 600C. The cells with the 3-D textile anode,
+Gd:CeO2-Li/Na2CO3 composite electrolyte, and Sm0.5Sr0.5CoO3 (SSC) cathode have
+demonstrated excellent performance with maximum power densities of 143, 196,
+and 325 mW cm-2 at 500, 550, and 600C, respectively. At 500C, the cells could
+be operated steadily with a rated power density of ~0.13 W cm-2 at a constant
+current density of 0.15 A cm-2 with a carbon utilization over 86%. The
+significant improvement of the cell performance at such temperatures attributes
+to the high synergistic conduction of the composite electrolyte and the
+superior 3-D anode structure which offers more paths for carbon catalytic
+oxidation. Our results indicate the feasibility of direct electrochemical
+oxidation of solid carbon at 500-600C with a high carbon utilization,
+representing a promising strategy to develop 3-D architected electrodes for
+fuel cells and other electrochemical devices.",1802.05789v1
+2018-02-26,III-V Tri-Gate Quantum Well MOSFET: Quantum Ballistic Simulation Study for 10nm Technology and Beyond,"In this work, quantum ballistic simulation study of a III-V tri-gate MOSFET
+has been presented. At the same time, effects of device parameter variation on
+ballistic, subthrshold and short channel performance is observed and presented.
+The ballistic simulation result has also been used to observe the electrostatic
+performance and Capacitance-Voltage characteristics of the device. With
+constant urge to keep in pace with Moore's law as well as aggressive scaling
+and device operation reaching near ballistic limit, a full quantum transport
+study at 10nm gate length is necessary. Our simulation reveals an increase in
+device drain current with increasing channel cross-section. However short
+channel performance and subthreshold performance get degraded with channel
+cross-section increment. Increasing device cross-section lowers threshold
+voltage of the device. The effect of gate oxide thickness on ballistic device
+performance is also observed. Increase in top gate oxide thickness affects
+device performance only upto a certain value. The thickness of the top gate
+oxide however shows no apparent effect on device threshold voltage. The
+ballistic simulation study has been further used to extract ballistic injection
+velocity of the carrier and ballistic carrier mobility in the channel. The
+effect of device dimension and gate oxide thickness on ballistic velocity and
+effective carrier mobility is also presented.",1802.09136v1
+2018-11-13,"Computationally-driven, high throughput identification of CaTe and Li$_\textrm{3}$Sb as promising candidates for high mobility $p$-type transparent conducting materials","High-performance $p$-type transparent conducting materials (TCMs) must
+exhibit a rare combination of properties including high mobility, transparency
+and $p$-type dopability. The development of high-mobility/conductivity $p$-type
+TCMs is necessary for many applications such as solar cells, or transparent
+electronic devices. Oxides have been traditionally considered as the most
+promising chemical space to dig out novel $p$-type TCMs. However, non-oxides
+might perform better than traditional $p$-type TCMs (oxides) in terms of
+mobility. We report on a high-throughput (HT) computational search for
+non-oxide $p$-type TCMs from a large dataset of more than 30,000 compounds
+which identified CaTe and Li$_\textrm{3}$Sb as very good candidates for
+high-mobility $p$-type TCMs. From our calculations, both compounds are expected
+to be $p$-type dopable: intrinsically for Li$_\textrm{3}$Sb while CaTe would
+require extrinsic doping. Using electron-phonon computations, we estimate hole
+mobilities at room-temperature to be about 20 and 70 cm$^2$/Vs for CaTe and
+Li$_\textrm{3}$Sb, respectively. The computed hole mobility for
+Li$_\textrm{3}$Sb is quite exceptional and comparable with the electron
+mobility in the best $n$-type TCMs.",1811.05390v1
+2018-11-27,A protonated brownmillerite electrolyte for superior low-temperature proton conductivity,"Design novel solid oxide electrolyte with enhanced ionic conductivity forms
+one of the Holy Grails in the field of materials science due to its great
+potential for wide range of energy applications. Conventional solid oxide
+electrolyte typically requires elevated temperature to activate the ionic
+transportation, while it has been increasing research interests to reduce the
+operating temperature due to the associated scientific and technological
+importance. Here, we report a conceptually new solid oxide electrolyte,
+HSrCoO2.5, which shows an exceptional enhanced proton conductivity at low
+temperature region (from room temperature to 140 oC). Combining both the
+experimental results and corresponding first-principles calculations, we
+attribute these intriguing properties to the extremely-high proton
+concentration as well as the well-ordered oxygen vacancy channels inherited
+from the novel crystalline structure of HSrCoO2.5. This result provides a new
+strategy to design novel solid oxide electrolyte with excellent proton
+conductivity for wide ranges of energy-related applications.",1811.10802v1
+2018-11-29,Detection and spatial mapping of conductive filaments in metal/oxide/metal cross-point devices,"A simple means of detecting and spatially mapping volatile and nonvolatile
+conductive filaments in metal/oxide/metal cross-point devices is introduced and
+its application demonstrated. The technique is based on thermal discolouration
+of a thin photoresist layer deposited on the top electrode of the cross-point
+device and relies on the increase in temperature produced by local Joule
+heating of an underlying conductive filament. Finite element modelling of the
+temperature distribution and its dependencies shows that the maximum
+temperature at the top-electrode/photoresist interface is particularly
+sensitive to the top-electrode thickness. The technique is demonstrated on NbOx
+based metal-oxide-metal cross-point devices with a 25 nm thick top (Pt)
+electrode, where it is used to undertake a statistical analysis of the filament
+location as a function of device area. This shows that filament formation is
+heterogeneous. The majority of filaments form preferentially along the
+top-electrode edge and the fraction of these increases with decreasing device
+area. Transmission electron microscopy of the top and bottom electrode edges is
+used to explain this observation and suggests that it is due to a reduction in
+the effective oxide thickness in this region.",1811.11889v1
+2019-05-03,Strain engineering of epitaxial oxide heterostructures beyond substrate limitations,"The limitation of commercially available single-crystal substrates and the
+lack of continuous strain tunability preclude the ability to take full
+advantage of strain engineering for further exploring novel properties and
+exhaustively studying fundamental physics in complex oxides. Here we report an
+approach for imposing continuously tunable, large epitaxial strain in oxide
+heterostructures beyond substrate limitations by inserting an interface layer
+through tailoring its gradual strain relaxation. Taking BiFeO3 as a model
+system, we demonstrate that the introduction of an ultrathin interface layer
+allows the creation of a desired strain that can induce phase transition and
+stabilize a new metastable super-tetragonal phase as well as morphotropic phase
+boundaries overcoming substrate limitations. Furthermore, continuously tunable
+strain from tension to compression can be generated by precisely adjusting the
+thickness of the interface layer, leading to the first achievement of
+continuous O-R-T phase transition in BiFeO3 on a single substrate. This
+proposed route could be extended to other oxide heterostructures, providing a
+platform for creating exotic phases and emergent phenomena.",1905.01070v2
+2019-05-29,Growth of metallic delafossite PdCoO2 by molecular beam epitaxy,"The Pd, and Pt based ABO2 delafossites are a unique class of layered,
+triangular oxides with 2D electronic structure and a large conductivity that
+rivals the noble metals. Here, we report successful growth of the metallic
+delafossite PdCoO2 by molecular beam epitaxy (MBE). The key challenge is
+controlling the oxidation of Pd in the MBE environment where phase-segregation
+is driven by the reduction of PdCoO2 to cobalt oxide and metallic palladium.
+This is overcome by combining low temperature (300 {\deg}C) atomic
+layer-by-layer MBE growth in the presence of reactive atomic oxygen with a
+post-growth high-temperature anneal. Thickness dependence (5-265 nm) reveals
+that in the thin regime (<75 nm), the resistivity scales inversely with
+thickness, likely dominated by surface scattering; for thicker films the
+resistivity approaches the values reported for the best bulk-crystals at room
+temperature, but the low temperature resistivity is limited by structural
+twins. This work shows that the combination of MBE growth and a post-growth
+anneal provides a route to creating high quality films in this interesting
+family of layered, triangular oxides.",1905.12549v2
+2020-07-01,Closing the gap between theory and experiment for lithium manganese oxide spinels using a high-dimensional neural network potential,"Many positive electrode materials in lithium ion batteries include transition
+metals which are difficult to describe by electronic structure methods like
+density functional theory (DFT) due to the presence of multiple oxidation
+states. A prominent example is the lithium manganese oxide spinel
+Li$_x$Mn$_2$O$_4$ with $0\leq x\leq2$. While DFT, employing the local hybrid
+functional PBE0r, provides a reliable description, the need for extended
+computer simulations of large structural models remains a significant
+challenge. Here, we close this gap by constructing a DFT-based high-dimensional
+neural network potential (HDNNP) providing accurate energies and forces at a
+fraction of the computational costs. As different oxidation states and the
+resulting Jahn-Teller distortions represent a new level of complexity for
+HDNNPs, the potential is carefully validated by performing X-ray diffraction
+experiments. We demonstrate that the HDNNP provides atomic level details and is
+able to predict a series of properties like the lattice parameters and
+expansion with increasing Li content or temperature, the orthorhombic to cubic
+transition, the lithium diffusion barrier, and the phonon frequencies. We show
+that for understanding these properties access to large time and length scales
+as enabled by the HDNNP is essential to close the gap between theory and
+experiment.",2007.00327v2
+2020-07-07,Crystal Engineering and Ferroelectricity at the Nanoscale in Epitaxial 1D Manganese Oxide on Silicon,"Ferroelectric oxides have attracted much attention due to their wide range of
+applications, especially in electronic devices such as nonvolatile memories and
+tunnel junctions. As a result, the monolithic integration of these materials
+into silicon technology and its nanostructuration to develop alternative
+cost-effective processes are among the central points in current technology. In
+this work, we used a chemical route to obtain nanowire thin films of a novel
+Sr1+{\delta}Mn8O16 (SMO) hollandite-type manganese oxide on silicon. Scanning
+transmission electron microscopy combined with crystallographic computing
+reveals a crystal structure comprising hollandite and pyrolusite units sharing
+the edges of their MnO6 octahedra, resulting in three types of tunnels arranged
+along the c axis, where ordering of the Sr atoms produces a natural symmetry
+breaking. The novel structure gives rise to a ferroelectricity and
+piezoelectricity, as revealed by local Direct Piezoelectric Force Microscopy
+measurements, which confirmed the ferroelectric nature of SMO nanowire thin
+films at room temperature and showed a piezoelectric coefficient d33 value of
+22,6 pC/N. Moreover, we proved that flexible vertical SMO nanowires can be
+harvested and converted into electric output energy through the piezoelectric
+effect, showing an excellent deformability and high interface recombination.
+This work indicates the possibility of engineering the integration of 1D
+manganese oxides on silicon, a step which precedes the production of
+microelectronic devices.",2007.03452v2
+2020-07-27,Primordial black holes in a dimensionally oxidizing Universe,"The spontaneous creation of primordial black holes in a violently expanding
+Universe is a well studied phenomenon. Based on quantum gravity arguments, it
+has been conjectured that the early Universe might have undergone a lower
+dimensional phase before relaxing to the current $(3 + 1)$ dimensional state.
+In this article we combine the above phenomena: we calculate the pair creation
+rates of black holes nucleated in an expanding Universe, by assuming a
+dimensional evolution, we term ``oxidation'', from $(1 + 1)$ to $(2 + 1)$ and
+finally to $(3 + 1)$ dimensions. Our investigation is based on the no boundary
+proposal that allows for the construction of the required gravitational
+instantons. If, on the one hand, the existence of a dilaton non-minimally
+coupled to the metric is necessary for black holes to exist in the $(1 + 1)$
+phase, it becomes, on the other hand, trivial in $(2 + 1)$ dimensions.
+Nevertheless, the dilaton might survive the oxidation and be incorporated in a
+modified theory of gravity in $(3 + 1)$ dimensions: by assuming that our
+Universe, in its current state, originates from a lower-dimensional oxidation,
+one might be led to consider the pair creation rate in a sub-class of the
+Horndeski action. Our findings for this case show that, for specific values of
+the Galileon coupling to the metric, the rate can be unsuppressed. This would
+imply the possibility of compelling parameter bounds for non-Einstein theories
+of gravity by using the spontaneous black hole creation.",2007.13653v2
+2020-07-29,Ligand Dependent Oxidation Dictates the Performance Evolution of High Efficiency PbS Quantum Dot Solar Cells,"Lead sulfide (PbS) quantum dot (QD) photovoltaics have reached impressive
+efficiencies of 12%, making them particularly promising for future
+applications. Like many other types of emerging photovoltaic devices, their
+environmental instability remains the Achilles heel of this technology. In this
+work, we demonstrate that the degradation processes in PbS QDs which are
+exposed to oxygenated environments are tightly related to the choice of
+ligands, rather than their intrinsic properties. In particular, we demonstrate
+that while 1,2-ethanedithiol (EDT) ligands result in significant oxidation of
+PbS, lead iodide/lead bromide (PbX2) coated PbS QDs show no signs of oxidation
+or degradation. Consequently, since the former is ubiquitously used as a hole
+extraction layer in QD solar cells, it is predominantly responsible for the
+device performance evolution. The oxidation of EDT-PbS QDs results in a
+significantly reduced effective QD size, which triggers two competing
+processes: improved energetic alignment that enhances electron blocking, but
+reduced charge transport through the layer. At early times, the former process
+dominates, resulting in the commonly reported, but so far not fully explained
+initial increase in performance, while the latter governs the onset of
+degradation and deterioration of the photovoltaic performance. Our work
+highlights that the stability of PbS quantum dot solar cells can be
+significantly enhanced by an appropriate choice of ligands for all device
+components.",2007.14678v1
+2020-07-30,Thermal Stability of Hafnium Zirconium Oxide on Transition Metal Dichalcogenides,"Ferroelectric oxides interfaced with transition metal dichalcogenides (TMDCs)
+offer a promising route toward ferroelectric-based devices due to lack of
+dangling bonds on the TMDC surface leading to a high-quality and abrupt
+ferroelectric/TMDC interface. In this work, the thermal stability of this
+interface is explored by first depositing hafnium zirconium oxide (HZO)
+directly on geological MoS2 and as-grown WSe2, followed by sequential annealing
+in ultra-high vacuum (UHV) over a range of temperatures (400-800 {\deg}C), and
+examining the interface through X-ray photoelectron spectroscopy (XPS). We show
+that the nucleation and stability of HZO grown through atomic layer deposition
+(ALD) varied depending on functionalization of the TMDC, and the deposition
+conditions can cause tungsten oxidation in WSe2. It was observed that HZO
+deposited on non-functionalized MoS2 was unstable and volatile upon annealing,
+while HZO on functionalized MoS2 was stable in the 400-800 {\deg}C range. The
+HZO/WSe2 interface was stable until 700 {\deg}C, after which Se began to evolve
+from the WSe2. In addition, there is evidence of oxygen vacancies in the HZO
+film being passivated at high temperatures. Lastly, X-ray diffraction (XRD) was
+used to confirm crystallization of the HZO within the temperature range
+studied.",2007.15685v1
+2010-05-05,Ni(OH)2 Nanoplates Grown on Graphene as Advanced Electrochemical Pseudocapacitor Materials,"Ni(OH)2 nanocrystals grown on graphene sheets with various degrees of
+oxidation are investigated as electrochemical pseudocapacitor materials for
+potential energy storage applications. Single-crystalline Ni(OH)2 hexagonal
+nanoplates directly grown on lightly-oxidized, electrically-conducting graphene
+sheets (GS) exhibit a high specific capacitance of ~1335F/g at a charge and
+discharge current density of 2.8A/g and ~953F/g at 45.7A/g with excellent
+cycling ability. The high specific capacitance and remarkable rate capability
+are promising for applications in supercapacitors with both high energy and
+power densities. Simple physical mixture of pre-synthesized Ni(OH)2 nanoplates
+and graphene sheets show lower specific capacitance, highlighting the
+importance of direct growth of nanomaterials on graphene to impart intimate
+interactions and efficient charge transport between the active nanomaterials
+and the conducting graphene network. Single-crystalline Ni(OH)2 nanoplates
+directly grown on graphene sheets also significantly outperform small Ni(OH)2
+nanoparticles grown on heavily-oxidized, electrically-insulating graphite oxide
+(GO), suggesting that the electrochemical performance of these composites are
+dependent on the quality of graphene substrates and the morphology and
+crystallinity of the nanomaterials grown on top. These results suggest the
+importance of rational design and synthesis of graphene-based nanocomposite
+materials for high-performance energy applications.",1005.0853v1
+2010-05-20,Oxidation of CO on surface hematite in high CO2 atmospheres,"We propose a mechanism for the oxidation of gaseous CO into CO2 occurring on
+the surface mineral hematite (Fe2O3(s)) in hot, CO2-rich planetary atmospheres,
+such as Venus. This mechanism is likely to constitute an important source of
+tropospheric CO2 on Venus and could at least partly address the CO2 stability
+problem in Venus' stratosphere, since our results suggest that atmospheric CO2
+is produced from CO oxidation via surface hematite at a rate of 0.4 Petagrammes
+(Pg) CO2 per (Earth) year on Venus which is about 45% of the mass loss of CO2
+via photolysis in the Venusian stratosphere. We also investigated CO oxidation
+via the hematite mechanism for a range of planetary scenarios and found that
+modern Earth and Mars are probably too cold for the mechanism to be important
+because the rate-limiting step, involving CO(g) reacting onto the hematite
+surface, proceeds much slower at lower temperatures. The mechanism may feature
+on extrasolar planets such as Gliese 581c or CoRoT-7b assuming they can
+maintain solid surface hematite which e.g. starts to melt above about 1200K.
+The mechanism may also be important for hot Hadean-type environments and for
+the emerging class of hot Super-Earths with planetary surface temperatures
+between about 600-900K.",1005.3588v1
+2014-03-12,First Principles Study of Photo-oxidation Degradation Mechanisms in P3HT for Organic Solar Cells,"We present a theoretical study of degradation mechanisms for photoinduced
+oxidation in organic polymers in the condensed phase, using
+poly(3-hexylthiophene)(P3HT) as an example. Applying density functional theory
+with a hybrid density functional and periodic boundary conditions that account
+for steric effects and permit the modeling of interchain chemical reactions, we
+investigate reaction pathways that may lead to the oxidation of thiophene
+backbone as a critical step toward disrupting the polymer conjugation. We
+calculate energy barriers for reactions of the P3HT backbone with oxidizing
+agents including hydroxyl radical (OH$\cdot$), hydroperoxide (ROOH), and
+peroxyl radical (ROO$\cdot$), following a UV-driven radical reaction starting
+at the $\alpha$-carbon of the alkyl side chain as suggested by infrared (IR)
+and X-ray photoemission (XPS) spectrosocopy studies. The results strongly
+suggest that an attack of OH$\cdot$ on sulfur in P3HT is unlikely to be
+thermodynamically favored. On the other hand, an attack of a peroxyl radical on
+the side chain on the P3HT backbone may provide low barrier reaction pathways
+to photodegradation of P3HT and other polymers with side chains. The condensed
+phase setting is found to qualitatively affect predictions of degradation
+processes.",1403.3102v2
+2016-11-07,Unique catalytic decomposition and reduction of hydrogen peroxide and organic peroxides on magnesia (001) promoted by oxide-metal hybrid nanostructure,"The detection, removal and reduction of hydrogen peroxide is of significant
+importance for its increasing application in the areas of environment, food,
+electrochemistry and clinical laboratory. Herein the dissociative adsorption
+behavior of hydrogen peroxide on ultrathin magnesia (001) films deposited on
+transition metal is uncovered for the first time by employing periodic
+density-functional theory calculations with van der Waals corrections. The
+hydrogen peroxide is dissociated smoothly and reduced to surface hydroxyls on
+MgO(001)/TM, and the dissociative adsorption energies of all the considered
+fragmentation configurations are substantially negative, demonstrating
+dissociation and reduction of hydrogen peroxide on MgO(001)/TM is
+thermodynamically favorable. The dissociative adsorption energy decreases
+monotonously with increasing film thickness, demonstrating the lower reactivity
+of thick oxide films. Moreover, we examined the suitability of several
+transition metal slabs (molybdenum, silver, vanadium, tungsten and gold)
+combined with magnesia for splitting hydrogen peroxide. The dissociative
+adsorption energies enhance when the lattice constants of substrate slabs
+increase, indicating the chemisorption strength can be tuned by category of
+metal slabs as well as thickness of oxide film. The mechanism of reactivity
+enhancement for energetically and dynamically favorable decomposition of
+hydrogen peroxide on supported magnesia is elucidated by characterizing the
+geometric structures and electronic properties. The fragmentation and reduction
+of diethyl peroxide and peroxyacetone are also studied to reveal the catalytic
+activity of ultrathin magnesia toward splitting organic peroxides. The results
+are wished to provide useful clue for detecting and reducing hydrogen peroxide
+and organic peroxides by employing oxide-metal hybrid nanostructure.",1611.01897v2
+2016-11-16,First-principles calculations that clarify energetics and reactions of oxygen adsorption and carbon desorption on 4H-SiC ($11\bar20$) surface,"We report static and dynamic first-principles calculations that provide
+atomistic pictures of the initial stage of the oxidation processes occurring at
+the ($11\bar20$) surface of 4H-SiC. Our results unveil reaction pathways and
+their associated free-energy barriers for the adsorption of oxygen and the
+desorption of carbon atoms. We find that oxygen adsorption shows structural
+multi-stability and that the surface-bridge sites are the most stable and
+crucial sites for subsequent oxidation. We find that an approaching O$_2$
+molecule is adsorbed, then dissociated and finally migrates toward these
+surface-bridge sites with a free-energy barrier of 0.7 eV at the ($11\bar20$)
+surface. We also find that a CO molecule is desorbed from the metastable
+oxidized structure upon the overcoming of a free-energy barrier of 2.4$\sim$2.6
+eV, thus constituting one of the annihilation process of C during the
+oxidation. The results of the CO molecule desorption on the ($11\bar20$)
+surface are compared with the ($000\bar1$) surface. A catalytic effect of
+dangling bonds at the surface, causing a drastic reduction of the CO desorption
+energy, is found on the ($000\bar1$) surface and the microscopic picture of the
+effect is ascribed to an electron transfer from the Si to C dangling bonds. The
+intrinsic ($11\bar20$) surface does not show this catalytic effect, and this is
+because the surface consists of an equal amount of Si and C dangling bonds and
+the electron transfer occurs before the desorption.",1611.05189v1
+2015-12-25,Controlled thinning and surface smoothening of silicon nanopillars,"A convenient method has been developed to thin electron beam fabricated
+Silicon nanopillars under controlled surface manipulation by transforming the
+surface of the pillars to an oxide shell layer followed by the growth of
+sacrificial ammonium silicon fluoride coating. The results show the formation
+of an oxide shell and a Silicon core without significantly changing the
+original length and shape of the pillars. The oxide shell layer thickness can
+be controlled from few nanometers up to few hundred nanometers. While down
+sizing in diameter, smooth Si pillar surfaces of less than 10 nm roughness
+within 2 {\mu}m were produced after exposure to vapors of HF and HNO3 mixture
+as evidenced by transmission electron microscopy (TEM) analysis. The attempt to
+expose for long durations leads to the growth of a thick oxide whose strain
+effect on pillars can be assessed by coupled LO-TO vibrational modes of Si-O
+bonds. Photoluminescence (PL) on the pillar structures which have been down
+sized exhibit visible and infrared emissions, which are attributable to
+microscopic pillars and to the confinement of excited carriers in Si core,
+respectively. The formation of a smooth core-shell structures while reducing
+the diameter of the Si pillars has a potential in fabricating nanoscale
+electronic devices and functional components.",1512.07996v1
+2015-12-30,Modelling the Role of Nitric Oxide in Cerebral Autoregulation,"Malfunction of the system which regulates the bloodflow in the brain is a
+major cause of stroke and dementia, costing many lives and many billions of
+pounds each year in the UK alone. This regulatory system, known as cerebral
+autoregulation, has been the subject of much experimental and mathematical
+investigation yet our understanding of it is still quite limited. One area in
+which our understanding is particularly lacking is that of the role of nitric
+oxide, understood to be a potent vasodilator. The interactions of nitric oxide
+with the better understood myogenic response remain un-modelled and poorly
+understood. In this thesis we present a novel model of the arteriolar control
+mechanism, comprising a mixture of well-established and new models of
+individual processes, brought together for the first time. We show that this
+model is capable of reproducing experimentally observed behaviour very closely
+and go on to investigate its stability in the context of the vasculature of the
+whole brain. In conclusion we find that nitric oxide, although it plays a
+central role in determining equilibrium vessel radius, is unimportant to the
+dynamics of the system and its responses to variation in arterial blood
+pressure. We also find that the stability of the system is very sensitive to
+the dynamics of Ca$^{2+}$ within the muscle cell, and that self-sustaining
+Ca$^{2+}$ waves are not necessary to cause whole-vessel radius oscillations
+consistent with vasomotion.",1512.09160v1
+2016-12-01,Mechanisms of initial oxidation of 4H-SiC (0001) and (000$\bar{1}$) surfaces unraveled by first-principles calculations,"We have performed electronic state calculations to clarify the initial stage
+of the oxidation of the Si- and C-faces in 4H-SiC based on the
+density-functional theory. We investigate how each Si and C atomic site is
+oxidized on C- and Si-face, and explore most probable reaction pathways,
+corresponding energy barriers, and possible defects generated during the
+oxidation. We have found that carbon annihilation process is different between
+on Si- and on C-face, and this difference causes different defects in
+interface; In C-face case, (1), carbon atoms are dissociated directly from the
+substrate as CO molecules. (2), after CO dissociation, 3-fold coordinated
+oxygen atoms (called Y-lid) are observed at the interface. (3), high density of
+C-dangling bonds can remain at the interface. In Si-face case, (1), C atoms
+inevitably form carbon nano clusters (composed of a few atoms) in interface to
+reduce the number of dangling bonds there. Moreover, we have found that the
+carbon nano clusters are composed of not only single but also double chemical
+bonds. (2), We have observed that CO molecules are dissociated from the carbon
+nano clusters in MD simulations. Furthermore, we have investigated whether
+H$_2$ and NO molecules react with the defects found in this study.",1612.00189v1
+2017-07-10,Analysis of Photocatalytic Nitrogen Fixation on Rutile TiO$_2$(110),"Photocatalytic nitrogen fixation provides a promising route to produce
+reactive nitrogen compounds at benign conditions. Titania has been reported as
+an active photocatalyst for reduction of dinitrogen to ammonia; however there
+is little fundamental understanding of how this process occurs. In this work
+the rutile (110) model surface is hypothesized to be the active site, and a
+computational model based on the Bayesian error estimation functional
+(BEEF-vdW) and computational hydrogen electrode is applied in order to analyze
+the expected dinitrogen coverage at the surface as well as the overpotentials
+for electrochemical reduction and oxidation. This is the first application of
+computational techniques to photocatalytic nitrogen fixation, and the results
+indicate that the thermodynamic limiting potential for nitrogen reduction on
+rutile (110) is considerably higher than the conduction band edge of rutile
+TiO$_2$, even at oxygen vacancies and iron substitutions. This work provides
+strong evidence against the most commonly reported experimental hypotheses, and
+indicates that rutile (110) is unlikely to be the relevant surface for nitrogen
+reduction. However, the limiting potential for nitrogen oxidation on rutile
+(110) is significantly lower, indicating that oxidative pathways may be
+relevant on rutile (110). These findings suggest that photocatalytic dinitrogen
+fixation may occur via a complex balance of oxidative and reductive processes.",1707.03031v3
+2018-01-08,The effect of heavy tars (toluene and naphthalene) on the electrochemical performance of an anode-supported SOFC running on bio-syngas,"The effect of heavy tar compounds on the performance of a Ni-YSZ anode
+supported solid oxide fuel cell was investigated. Both toluene and naphthalene
+were chosen as model compounds and tested separately with a simulated
+bio-syngas. Notably, the effect of naphthalene is almost negligible with pure
+H2 feed to the SOFC, whereas a severe degradation is observed when using a
+bio-syngas with an H2:CO = 1. The tar compound showed to have a remarkable
+effect on the inhibition of the WGS shift-reaction, possibly also on the CO
+direct electro-oxidation at the three-phase-boundary. An interaction through
+adsorption of naphthalene on nickel catalytic and electrocatalytic active sites
+is a plausible explanation for observed degradation and strong performance
+loss. Different sites seem to be involved for H2 and CO electro-oxidation and
+also with regard to catalytic water gas shift reaction. Finally, heavy tars
+(C>=10) must be regarded as a poison more than a fuel for SOFC applications,
+contrarily to lighter compounds such benzene or toluene that can directly
+reformed within the anode electrode. The presence of naphthalene strongly
+increases the risk of anode re-oxidation in a syngas stream as CO conversion to
+H2 is inhibited and also CH4 conversion is blocked.",1801.02557v1
+2018-09-21,Spectroscopic Signature of Oxidized Oxygen States in Peroxides,"Recent debates on the oxygen redox behaviors in battery electrodes have
+triggered a pressing demand for the reliable detection and understanding of
+non-divalent oxygen states beyond conventional absorption spectroscopy. Here,
+enabled by high-efficiency mapping of resonant inelastic X-ray scattering
+(mRIXS) coupled with first-principles calculations, we report distinct mRIXS
+features of the oxygen states in Li2O, Li2CO3, and especially, Li2O2, which are
+successfully reproduced and interpreted theoretically. mRIXS signals are
+dominated by valence-band decays in Li2O and Li2CO3. However, the oxidized
+oxygen in Li2O2 leads to partially unoccupied O-2p states that yield a specific
+intra-band excitonic feature in mRIXS. Such a feature displays a specific
+emission energy in mRIXS, which disentangles the oxidized oxygen states from
+the dominating transition-metal/oxygen hybridization features in absorption
+spectroscopy, thus providing critical hints for both detecting and
+understanding the oxygen redox reactions in transition-metal oxide based
+battery materials.",1809.08292v2
+2018-10-02,Thermomechanical properties of amorphous metallic tungsten-oxygen and tungsten-oxide coatings,"In this work, we investigate the correlation between morphology, composition,
+and the mechanical properties of metallic amorphous tungsten-oxygen and
+amorphous tungsten-oxide films deposited by Pulsed Laser Deposition. This
+correlation is investigated by the combined use of Brillouin Spectroscopy and
+the substrate curvature method. The stiffness of the films is strongly affected
+by both the oxygen content and the mass density. The elastic moduli show a
+decreasing trend as the mass density decreases and the oxygen-tungsten ratio
+increases. A plateaux region is detected in correspondence of the transition
+between metallic and oxide films. The compressive residual stresses, moderate
+stiffness and high local ductility that characterize compact amorphous
+tungsten-oxide films make them promising for applications involving thermal or
+mechanical loads. The coefficient of thermal expansion is quite high (i.e. 8.9
+$\cdot$ 10$^{-6}$ K$^{-1}$), being strictly correlated to the amorphous
+structure and stoichiometry of the films. Under thermal treatments they show a
+quite low relaxation temperature (i.e. 450 K). They crystallize into the
+$\gamma$ monoclinic phase of WO$_3$ starting from 670 K, inducing an increase
+by about 70\% of material stiffness.",1810.01201v2
+2019-06-13,Passivation-induced physicochemical alterations of the native surface oxide film on 316L austenitic stainless steel,"Time of Flight Secondary Ion Mass Spectroscopy, X-Ray Photoelectron
+Spectroscopy, in situ Photo-Current Spectroscopy and electrochemical analysis
+were combined to characterize the physicochemical alterations induced by
+electrochemical passivation of the surface oxide film providing corrosion
+resistance to 316L stainless steel. The as-prepared surface is covered by a ~2
+nm thick, mixed (Cr(III)-Fe(III)) and bi-layered hydroxylated oxide. The inner
+layer is highly enriched in Cr(III) and the outer layer less so. Molybdenum is
+concentrated, mostly as Mo(VI), in the outer layer. Nickel is only present at
+trace level. These inner and outer layers have band gap values of 3.0 and
+2.6-2.7 eV, respectively, and the oxide film would behave as an insulator.
+Electrochemical passivation in sulfuric acid solution causes the preferential
+dissolution of Fe(III) resulting in the thickness decrease of the outer layer
+and its increased enrichment in Cr(III) and Mo(IV-VI). The further Cr(III)
+enrichment of the inner layer causes loss of photoactivity and improved
+corrosion protection with the anodic shift of the corrosion potential and the
+increase of the polarization resistance by a factor of ~4. Aging in the passive
+state promotes the Cr enrichment in the inner barrier layer of the passive
+film.",1906.05544v1
+2019-06-25,Titanium Contacts to MoS2 with Interfacial Oxide: Interface Chemistry and Thermal Transport,"The deposition of a thin oxide layer at metal/semiconductor interfaces has
+been previously reported as a means of reducing contact resistance in 2D
+electronics. Using X-ray photoelectron spectroscopy with in-situ Ti deposition,
+we fabricate Au/Ti/TiOx/MoS2 samples as well as Au/Ti/MoS2 and Au/TiOx/MoS2 for
+comparison. Elemental titanium reacts strongly with MoS2 whereas no interface
+reactions are observed in the two types of samples containing TiOx/MoS2
+interfaces. Using time domain thermoreflectance for the measurement of thermal
+boundary conductance, we find that samples contacted with Ti and a thin TiOx
+layer at the interface (less than or equal to 1.5 nm) exhibit the same behavior
+as samples contacted solely with pure Ti. The Au/TiOx/MoS2 samples exhibit
+approximately 20% lower thermal boundary conductance, despite having the same
+MoS2 interface chemistry as the samples with thin oxide at the Ti/MoS2
+interface. We identify the mechanism for this phenomenon, attributing it to the
+different interfaces with the top Au contact. Our work demonstrates that the
+use of thin interfacial oxide layers to reduce electrical contact resistance
+does not compromise heat flow in 2D electronic devices. We note that the
+thicknesses of the Ti and TiOx layers must be considered for optimal thermal
+transport.",1906.10727v1
+2019-06-26,Near 100% CO Selectivity in Nanoscaled Iron-Based Oxygen Carriers for Chemical Looping Methane Partial Oxidation,"Chemical looping methane partial oxidation provides an energy and cost
+effective route for methane utilization. However, there is considerable CO2
+co-production in state-of-the-art chemical looping systems, rendering a
+decreased productivity in value-added fuels or chemicals. In this work, we show
+that the co-production of CO2 can be dramatically suppressed in methane partial
+oxidation reactions using iron oxide nanoparticles, with a size of 2~8 nm, as
+the oxygen carrier. To stabilize these nanoparticles at high temperatures, they
+are embedded in an ordered, gas-permeable mesoporous silica matrix. We
+experimentally obtained near 100% CO selectivity in a cyclic redox system at
+750{\deg}C to 935{\deg}C, which is a significantly lower temperature range than
+in conventional oxygen carrier systems. Density functional theory calculations
+elucidate the origins for such selectivity and reveal that CH4 adsorption
+energies decrease with increasing nanoparticle size. These calculations also
+show that low-coordinated lattice oxygen atoms on the surface of nanoparticles
+significantly promote Fe-O bond cleavage and CO formation. We envision that
+embedded nanostructured oxygen carriers have the potential to serve as a
+general materials platform for achieving 100% selectivity in redox reactions at
+high temperatures.",1906.11160v1
+2019-07-28,Effect of Functional Group on Electrical Switching Behaviour of an Imidazole Derivative in Langmuir-Blodgett Film,"Here we report the design and synthesis of an imidazole derivative namely
+1-benzyl-2,4,5-triaryl imidazole and its switching behaviour assembled onto
+Langmuir-Blodgett films. Monolayer characteristic of imidazole at the air-water
+interface has been studied by surface pressure vs area per molecule isotherm,
+hysteresis analysis and insitu Brewster Angle Microscopy . These studies
+indicated the formation of stable floating Langmuir film at the water subphase.
+Atomic Force Microscopy investigation confirmed the successful deposition of
+the Langmuir film onto solid substrate. Device consisted of 60 layers LB films
+of imidazole showed resistive bipolar switching behaviour irrespective of the
+first applied bias voltage polarity. Observed bipolar switching has been
+explained in terms of reduction oxidation process. Due to the presence of
+strong reducible group C double bond N in the imidazole core, reduction
+oxidation process takes place easily during bias. Presence of sharp reduction
+and oxidation peaks in the Cyclic Voltammetry measurement of 2 also supported
+this hypothesis. Presence of benzyl group with the imidazole core played the
+crucial rule in the reduction oxidation process and hence the switching
+behaviour. When benzyl group was replaced by a H then bipolar switching was not
+observed. In that case oxidizable group NH opposed the reduction process during
+bias. This type of bipolar switching is very promising for future technological
+applications in organic electronics.",1907.12004v1
+2019-09-26,Pd/Pt embedded CN monolayer as efficient catalysts for CO oxidation,"Single atom catalysts (SACs) based on 2D materials are identified to be
+efficient in many catalytic reaction. In this work, the catalytic performance
+of Pd/Pt embedded planar carbon nitride (CN) for CO oxidation, has been
+investigated via spin$-$polarized density functional theory calculations. We
+find that Pd/Pt can be firmly anchored in the porous CN monolayer due to the
+strong hybridization between Pd/Pt-d orbitals and adjacent N-2p orbitals. The
+resulting high adsorption energy and large diffusion barrier of Pd/Pt, ensuring
+the remarkable stability of the catalyst Pd/Pt@CN during CO oxidation reaction.
+The three distinct CO reaction mechanisms, namely, Eley-Rideal (ER),
+Langmuir-Hinshelwood (LH), and Tri-molecular Eley-Rideal (TER), are taken into
+consideration comparatively. Intriguingly, the oxidation reaction on Pd@CN
+prefers to proceed through the less common TER mechanism, where two CO
+molecules and one O2 molecule need to cross a small reaction barrier of 0.48
+eV, and finally dissociate into two CO2 molecules. However, the LH mechanism is
+the most relevant one on Pt@CN with a rate-limiting reaction barrier of 0.68
+eV. Moreover, the origin of SAC's reactivity enhancement is the electronic
+""acceptance$-$donation"" interaction caused by orbital hybridization between
+Pd/Pt and preadsorbed O2/CO. Our findings are expected to widen the catalytic
+application of carbon based 2D materials.",1909.11922v1
+2019-10-11,Low work function thin film growth for high efficiency thermionic energy converter: Coupled Kelvin probe and photoemission study of potassium oxide,"Recent researches in thermal energy harvesting have revealed the remarkable
+efficiency of thermionic energy converters comprising very low work function
+electrodes. From room temperature and above, this kind of converter could
+supply low power devices such as autonomous sensor networks. In this type of
+thermoelectric converters, current injection is mainly governed by a mechanism
+of thermionic emission at the hot electrode which explains the interest for low
+work function coating materials. In particular, alkali metal oxides have been
+identified as excellent candidates for coating converter electrodes. This paper
+is devoted to the synthesis and characterization of potassium peroxide K2O2
+onto silicon surfaces. To determine optimal synthesis conditions of K2O2, we
+present diagrams showing the different oxides as a function of temperature and
+oxygen pressure from which phase stability characteristics can be determined.
+From the experimental standpoint, we present results on the synthesis of
+potassium oxide under ultra high vacuum and controlled temperature. The
+resulting surface is characterized in situ by means of photoemission
+spectroscopy (PES) and contact potential difference (CPD) measurements. A work
+function of 1.35 eV is measured which and the expected efficiency of the
+corresponding converter is discussed. It is generally assumed that the decrease
+of the work function in the alkali/oxygen/ silicon system, is attributed to the
+creation of a surface dipole resulting from a charge transfer between the
+alkali metal and oxygen.",1910.05166v1
+2019-10-28,Tailored Graphenic Structures Directly Grown on Titanium Oxide Boost the Interfacial Charge Transfer,"The successful application of titanium oxide-graphene hybrids in the fields
+of photocatalysis, photovoltaics and photodetection strongly depends on the
+interfacial contact between both materials. The need to provide a good coupling
+between the enabling conductor and the photoactive phase prompted us to
+directly grow conducting graphenic structures on TiO2 crystals. We here report
+on the direct synthesis of tailored graphenic structures by using Plasma
+Assisted Chemical Vapour Deposition that present a clean junction with the
+prototypical titanium oxide (110) surface. Chemical analysis of the interface
+indicates chemical bonding between both materials. Photocurrent measurements
+under UV light illumination manifest that the charge transfer across the
+interface is efficient. Moreover, the influence of the synthesis atmosphere,
+gas precursor (C2H2) and diluents (Ar, O2), on the interface and on the
+structure of the as-grown graphenic material is assessed. The inclusion of O2
+promotes vertical growth of partially oxidized carbon nanodots/rods with
+controllable height and density. The deposition with Ar results in continuous
+graphenic films with low resistivity (6.8x10-6 ohm x m). The synthesis
+protocols developed here are suitable to produce tailored carbon-semiconductor
+structures on a variety of practical substrates as thin films, pillars or
+nanoparticles.",1910.12667v1
+2019-12-24,First-principles study on luminescence properties of Eu-doped defect pyrochlore oxide KNbWO$_6\cdot$H$_2$O:Eu$^{3+}$,"Defect pyrochlore oxides have attracted a great interest as promising
+luminescent materials due to their flexible composition and high electron/hole
+mobility. In this work, we investigate the structural and electronic properties
+of lanthanide-doped (Ln) defect pyrochlore oxides \ce{KNbWO6}:0.125Ln$^{3+}$ by
+using first-principles calculations. We perform structural optimizations of
+various defect pyrochlore models and calculate their electronic structures,
+revealing that hydration has a significant influence on both local symmetry
+around Eu$^{3+}$ ion and band structures with an alteration of their
+luminescent behaviour. In the hydrated compounds, the electric-dipole
+$^5$D$_0-^7$F$_2$ transition is found to be partially suppressed by the raised
+local symmetry, and the water molecules in the compounds can mediate the
+non-radiative energy transfer between the activator Eu$^{3+}$ ions and the
+host, resulting in the quenching effect. It turns out that the oxygen vacancies
+are detrimental to luminescence as they reduce the Eu$^{3+}$ ion in its
+vicinity to Eu$^{2+}$ ion and also serve as traps for conduction electrons
+excited by incident light. Our calculations for \ce{KNbWO6}:0.125Ln$^{3+}$ (Ln
+= Ce, Pr, Nd, Pm, Sm) support that defect pyrochlore oxide \ce{KNbWO6} can also
+be used as luminescence host for Ln$^{3+}$ ion doping, giving a valuable
+insight into a variation trend in luminescent properties of these materials at
+atomic level.",2001.02059v1
+2019-12-29,Bio-inspired Band Gap Engineering of Zinc Oxide by Intracrystalline Incorporation of Amino Acids,"During a bioInspired crystallization process, incorporation of amino acids
+into the crystal structure of ZnO induces lattice strain that leads to linear
+bandgap shifts.",2001.02064v1
+2020-01-14,"Interplay among Work Function, electronic structure and stoichiometry in nanostructured vanadium oxides films","The work function is the parameter of greatest interest in many technological
+applications involving charge exchange mechanisms at the interface. The
+possibility to produce samples with a controlled work function is then
+particularly interesting, albeit challenging. We synthetized nanostructured
+vanadium oxides films by a room temperature Supersonic Cluster Beam Deposition
+method, obtaining samples with tunable stoichiometry and work function (3.7-7
+eV). We present an investigation of the electronic structure of several
+vanadium oxides films as a function of the oxygen content via in-situ Auger,
+valence-band photoemission spectroscopy and work function measurements. The
+experiments probed the partial 3d density of states, highlighting the presence
+of strong V3d-O2p and V3d-V4s hybridization which influence 3d occupation. We
+show how controlling the stoichiometry of the sample implies a control over
+work function, and that the access to nanoscale quantum confinement can be
+exploited to increase the work function of the sample relative to the bulk
+analogue. In general, the knowledge of the interplay among work function,
+electronic structure, and stoichiometry is strategic to match nanostructured
+oxides to their target applications.",2001.04695v1
+2020-12-19,Investigation of microwave loss induced by oxide regrowth in high-Q Nb resonators,"The coherence of state-of-the-art superconducting qubit devices is
+predominantly limited by two-level-system defects, found primarily at amorphous
+interface layers. Reducing microwave loss from these interfaces by proper
+surface treatments is key to push the device performance forward. Here, we
+study niobium resonators after removing the native oxides with a hydrofluoric
+acid etch. We investigate the reappearance of microwave losses introduced by
+surface oxides that grow after exposure to the ambient environment. We find
+that losses in quantum devices are reduced by an order of magnitude, with
+internal Q-factors reaching up to 7 $\cdot$ 10$^6$ in the single photon regime,
+when devices are exposed to ambient conditions for 16 min. Furthermore, we
+observe that Nb2O5 is the only surface oxide that grows significantly within
+the first 200 hours, following the extended Cabrera-Mott growth model. In this
+time, microwave losses scale linearly with the Nb$_2$O$_5$ thickness, with an
+extracted loss tangent tan$\delta$ = 9.9 $\cdot$ 10$^{-3}$. Our findings are of
+particular interest for devices spanning from superconducting qubits,
+quantum-limited amplifiers, microwave kinetic inductance detectors to single
+photon detectors.",2012.10761v2
+2021-01-26,Deterministic influence of substrate-induced oxygen vacancy diffusion on $Bi_{2}WO_{6}$ thin film growth,"In oxide epitaxy, the growth temperature and background oxygen partial
+pressure are considered as the most critical factors that control the phase
+stability of an oxide thin film. Here, we report an unusual case wherein
+diffusion of oxygen vacancies from the substrate overpowers the growth
+temperature and oxygen partial pressure to deterministically influence the
+phase stability of $Bi_{2}WO_{6}$ thin film grown by the pulsed laser
+deposition technique. We show that when grown on an oxygen-deficient
+$SrTiO_{3}$ substrate, the $Bi_{2}WO_{6}$ film exhibits a mixture of (001) and
+(100)/(010)-oriented domains alongside (001)-oriented impurity $WO_{3}$ phases.
+The (100)/(010)-oriented $Bi_{2}WO_{6}$ phases form a self-organized 3D
+nanopillar-structure, yielding a very rough film surface morphology. Oxygen
+annealing of the substrate or using a few monolayer-thick $SrRuO_{3}$ as the
+blocking layer for oxygen vacancy diffusion enables growing high-quality
+single-crystalline $Bi_{2}WO_{6}$ (001) thin film exhibiting an atomically
+smooth film surface with step-terrace structure. We propose that the large
+oxide-ion conductivity of $Bi_{2}WO_{6}$ facilitates diffusion of oxygen
+vacancies from the substrate during the film growth, accelerating the
+evaporation of volatile Bismuth (Bi), which hinders the epitaxial growth. Our
+work provides a general guideline for high-quality thin film growth of
+Aurivillius compounds and other oxide-ion conductors containing volatile
+elements.",2101.10559v1
+2012-05-07,Uniform wafer-scale synthesis of graphene on evaporated Cu (111) film with quality comparable to exfoliated monolayer,"Monolayer graphene has been grown on crystallized Cu (111) films on standard
+oxidized Si 100 mm wafers. The monolayer graphene demonstrates high uniformity
+(>97% coverage), with immeasurable defects (>95% defect-negligible) across the
+entire wafer. Key to these results is the phase transition of evaporated copper
+films from amorphous to crystalline at the growth temperature as corroborated
+by X-ray diffraction and electron backscatter diffraction. Noticeably, phase
+transition of copper film is observed on technologically ubiquitous oxidized Si
+wafer where the oxide is a standard amorphous thermal oxide. Ion mass
+spectroscopy indicates that the copper films can be purposely hydrogen-enriched
+during a hydrogen anneal which subsequently affords graphene growth with a sole
+carbonaceous precursor for low defect densities. Owing to the strong hexagonal
+lattice match, the graphene domains align to the Cu (111) domains, suggesting a
+pathway for increasing the graphene grains by maximizing the copper grain
+sizes. Fabricated graphene transistors on a flexible polyimide film yield a
+peak carrier mobility ~4,930 cm2/Vs.",1205.1546v1
+2017-05-17,Calibration of the NDHA model to describe N2O dynamics from respirometric assays,"The NDHA model comprehensively describes nitrous oxide (N2O) producing
+pathways by both autotrophic ammonium oxidizing and heterotrophic bacteria. The
+model was calibrated via a set of targeted extant respirometric assays using
+enriched nitrifying biomass from a lab-scale reactor. Biomass response to
+ammonium, hydroxylamine, nitrite and N2O additions under aerobic and anaerobic
+conditions were tracked with continuous measurement of dissolved oxygen (DO)
+and N2O. The sequential addition of substrate pulses allowed the isolation of
+oxygen-consuming processes. The parameters to be estimated were determined by
+the information content of the datasets using identifiability analysis. Dynamic
+DO profiles were used to calibrate five parameters corresponding to endogenous,
+nitrite oxidation and ammonium oxidation processes. The subsequent N2O
+calibration was not significantly affected by the uncertainty propagated from
+the DO calibration because of the high accuracy of the estimates. Five
+parameters describing the individual contribution of three biological N2O
+pathways were estimated accurately (variance/mean < 10% for all estimated
+parameters). The NDHA model response was evaluated with statistical metrics
+(F-test, autocorrelation function). The 95% confidence intervals of DO and N2O
+predictions based on the uncertainty obtained during calibration are studied
+for the first time. The measured data fall within the 95% confidence interval
+of the predictions, indicating a good model description. Overall, accurate
+parameter estimation and identifiability analysis of ammonium removal
+significantly decreases the uncertainty propagated to N2O production, which is
+expected to benefit N2O model discrimination studies and reliable full scale
+applications.",1705.05962v1
+2017-11-02,Non-equilibrium character of resistive switching and negative differential resistance in Ga-doped Cr2O3 system,"We have synthesized Ga-doped Cr2O3 system with compositions Cr1.45Ga0.55O3
+and Cr1.17Ga0.83O3 by chemical co-precipitation route and post annealing at
+800^C. The samples have been stabilized in rhombohedral crystal structure with
+space group R3C. The present work focuses on the study of non-linear
+current-voltage (I-V) characteristics of the samples, which exhibited many
+interesting electronic properties, e.g., I-V loop, resistive switching,
+bi-stable electronic states, and negative differential resistance. The
+non-equilibrium character of the I-V characteristics has been studied by
+measurement of bias voltage cycling up to 20 times and current relaxation with
+time at set bias voltage. The charge conduction process in the samples has been
+understood by analysing I-V curves using different phenomenological models
+based on electrode-limited and bulk-limited charge conduction mechanisms
+proposed for metal electrode-metal oxide-metal electrode (M-MO-M) junctions. It
+is understood that competitions between injection of charge carriers from metal
+electrode to metal oxide, charge flow through the material
+(trapping/de-trapping and recombination of charge carriers at the defect
+sites), space charge formation at the junctions of electrodes and metal oxides,
+and ejection of electrons from metal oxide to metal electrode control the
+non-equilibrium I-V characteristics in the present samples.",1711.00687v1
+2018-03-29,Designing hybrid graphene oxide- gold nanoparticles for nonlinear optical response: Experiment and theory,"Nonlinear optical absorption of light by materials are weak due to its
+perturbative nature, although a strong nonlinear response is of crucial
+importance to applications in optical limiting and switching. Here we
+demonstrate experimentally and theoretically an extremely efficient scheme of
+excited state absorption by charge transfer between donor and acceptor
+materials as the new method to enhance the nonlinear absorption by orders of
+magnitude. With this idea, we have demonstrated strong excited state absorption
+(ESA) in reduced graphene oxide that otherwise shows increased transparency at
+high fluence and enhancement of ESA by one orders of magnitude in graphene
+oxide by attaching gold nanoparticles (AuNP) in the tandem configuration that
+acts as an efficient charge transfer pair when excited at the plasmonic
+wavelength. To explain the unprecedented enhancement, we have developed a
+five-level rate equation model based on the charge transfer between the two
+materials and numerically simulated the results. To understand the correlation
+of interfacial charge-transfer with the concentration and type of the
+functional ligands attached to the graphene oxide sheet, we have investigated
+the AuNP-graphene oxide interface with various possible ligand configurations
+from first-principles calculations. By using the strong ESA of our hybrid
+materials, we have fabricated liquid cell-based high-performance optical
+limiters with important device parameters better than that of the benchmark
+optical limiters.",1803.10919v1
+2018-08-30,Facile synthesis of 2D graphene oxide sheet enveloping ultrafine 1D LiMn2O4 as interconnected framework to enhance cathodic property for Li-ion battery,"Cubic spinel lithium manganese oxide (LiMn2O4) has been able to attract a
+great deal of attention over the years as a promising cathode material for
+large scale lithium ion batteries. Here a facile hydrothermal route followed by
+solid state reaction is developed using as grown ultrafine alpha-MnO2 nanorods
+to prepare one dimensional LiMn2O4 with 10-50nm diameters. To enhance the
+cathodic property of these nanorods, a unique synthesis technique of heat
+treatment is developed to grow 2D graphene oxide sheet enveloping 1D LiMn2O4 as
+interconnected framework. This nanocomposite 3D porous cathode exhibits a high
+specific charge capacity of 130mAh/g at 0.05C rate and Coulombic efficiency of
+about 98% after 100 cycles in the potential window of 3.5 to 4.3V versus Li/Li+
+with promising initial charge capacity retention of about 87%, and outstanding
+structural stability even after 100 cycles. Enhancement in the lithiation and
+delithiation processes leading to improved performance is likely to have its
+origin in the 2D conducting graphene oxide sheets. It allows for decreasing the
+Mn dissolution, improve the electron conductivity and reduce the Li-ion path
+diffusion inside the favourable morphology and crystallinity of the ultrafine
+1D LiMn2O4 nanorods, giving rise to a promising cathode nanocomposite.",1808.10150v1
+2019-01-30,Modelling functional properties of ferroelectric oxide thin films with a three-domain structure,"The properties of a ferroelectric, (001)-oriented, thin film clamped to a
+substrate are investigated analytically and numerically. The emphasis is on the
+tetragonal, polydomain, ferroelectric phase, using a three domain structure, as
+is observed experimentally. The previously used, very restrictive set of
+boundary conditions, arising from the domain walls, is relaxed, creating more
+modes for energy relaxation. It is argued that this approach gives a more
+realistic description of the clamped ferroelectric film.
+  It is shown that for the ferroelectric oxides PbZr_(1-x)Ti_xO_3} the
+tetragonal, polydomain phase is present over a wide range of substrate induced
+strains for x_Ti>0.5, corresponding to the tetragonal side of the bulk phase
+diagram. A polydomain, rhombohedral phase is present for x_Ti<0.5, at the bulk
+rhombohedral side. Phase-temperature diagrams, and ferroelectric, dielectric
+and piezoelectric properties, as well as lattice parameters, are calculated as
+function of substrate induced strain and applied field. The analytical
+formulation allows the decomposition of these properties into three different
+causes: domain wall motion, field induced elastic effects and piezoelectric
+effects. It is found that domain wall motion and polarization rotation of the
+in-plane oriented domains under an applied field contribute most to the
+properties, while the out-of-plane oriented domains hardly contribute.",1901.10883v2
+2019-02-11,Determination of conduction and valence band electronic structure of LaTiOxNy thin film,"The nitrogen substitution into the oxygen sites of several oxide materials
+leads to a reduction of the band gap to the visible light energy range, which
+makes these oxynitride semiconductors potential photocatalysts for efficient
+solar water splitting. Oxynitrides typically show a different crystal structure
+compare to the pristine oxide material. Since the band gap is correlated to
+both the chemical composition and the crystal structure, it is not trivial to
+distinguish what modifications of the electronic structure induced by the
+nitrogen substitution are related to compositional and/or structural effects.
+Here, X-ray emission and absorption spectroscopy is used to investigate the
+electronic structures of orthorhombic perovskite LaTiOxNy thin films in
+comparison with films of the pristine oxide LaTiOx with similar orthorhombic
+structure and cationic oxidation state. Experiment and theory show the expected
+upward shift in energy of the valence band maximum that reduces the band gap as
+a consequence of the nitrogen incorporation. But this study also shows that the
+conduction band minimum, typically considered almost unaffected by the nitrogen
+substitution, undergoes a significant downward shift in energy. For a rational
+design of oxynitride photocatalysts the observed changes of both the unoccupied
+and occupied electronic states have to be taken into account to justify the
+total band gap narrowing induced by the nitrogen incorporation.",1902.03845v1
+2019-02-12,Electronic band structure of ultimately thin silicon oxide on Ru(0001),"Silicon oxide can be formed in a crystalline form, when prepared on a
+metallic substrate. It is a candidate support catalyst and possibly the
+ultimately-thin version of a dielectric host material for two-dimensional
+materials (2D) and heterostructures. We determine the atomic structure and
+chemical bonding of the ultimately thin version of the oxide, epitaxially grown
+on Ru(0001). In particular, we establish the existence of two sub-lattices
+defined by metal-oxygen-silicon bridges involving inequivalent substrate sites.
+We further discover four electronic bands below Fermi level, at high binding
+energies, two of them forming a Dirac cone at K point, and two others forming
+semi-flat bands. While the latter two correspond to hybridized states between
+the oxide and the metal, the former relate to the topmost silicon-oxygen plane,
+which is not directly coupled to the substrate. Our analysis is based on high
+resolution X-ray photoelectron spectroscopy, angle-resolved photoemission
+spectroscopy, scanning tunneling microscopy, and density functional theory
+calculations.",1902.04514v1
+2019-02-13,Strain Controlling Catalytic Efficiency of Water Oxidation for Ni1-xFexOOH alloy,"A catalyst surface may be exposed to strain due to application of load or
+interfacing with a substrate with large lattice mismatch. In order to test the
+effect of strain on catalytic efficiency, we use Density Functional Theory +U
+(DFT+U) to model water oxidation on expanded and contracted surfaces of the
+Ni1-xFexOOH alloy, one of the best known catalysts for water splitting. We find
+that a low amount of iron content has a similar effect as of applying
+compressive strain. Due to high oxidation state of Fe4+ at the active site, the
+Fe-O bond is shorter than in pure FeOOH, which is beneficial for extracting
+electrons from states delocalized on Fe and Ni atoms. At 33% of Fe content the
+efficiency is even better since Fe3+ is at the active site and can easily
+change oxidation state during the reaction. However, the efficiency drops at
+higher iron percentages since the surface is unstable and may form FeOOH
+aggregates. We find that the best performance is obtained at 33% iron content
+and 5% expansion. Therefore, in addition to changing iron content, strain can
+also be used as a control handle for improving water splitting catalysis.",1902.04788v1
+2019-02-26,Bonding and oxidation protection of Ti${_2}$AlC and Cr${_2}$AlC for a Ni-based Superalloy,"Alumina forming, oxidation and thermal shock resistant MAX phases are of a
+high interest for high temperature applications. Herein we report, on bonding
+and resulting interactions between a Ni-based superalloy, NSA, and two alumina
+forming MAX phases. The diffusion couples Cr${_2}$AlC/Inconel-718/Ti${_2}$AlC
+were assembled and heated to 1000 or 1100{\deg}C in a vacuum hot press under
+loads corresponding to stresses of either 2 MPa or 20 MPa. The resulting
+interfaces were examined using X-ray diffraction, scanning electron microscopy
+and energy-dispersive X-ray spectroscopy. Good bonding between Cr${_2}$AlC and
+NSA was achieved after hot pressing at 1000{\deg}C and a contact pressure of
+only 2 MPa; in the case of Ti${_2}$AlC a higher temperature (1100{\deg}C) and
+pressure (20 MPa) were needed. In both cases, a diffusion bond was realized
+with no evidence of interfacial damage or cracking after cooling to room
+temperature. Twenty thermal cycles from room temperature to 1000{\deg}C showed
+that Ti${_2}$AlC is a poor oxidation barrier for Inconel-718. However, in the
+case of Cr${_2}$AlC no cracks, delamination nor surface degradation were
+observed, suggesting that this material could be used to protect Inconel-718
+from oxidation.",1902.10001v2
+2019-04-03,Reproducible Performance Improvements to Monolayer MoS2 Transistors through Exposed Material Forming Gas Annealing,"Metal-mediated exfoliation has been demonstrated as a promising approach for
+obtaining large-area flakes of 2D materials to fabricate prototypical
+nanoelectronics. However, several processing challenges related to organic
+contamination at the interfaces of the 2D material and the gate oxide must be
+overcome to realize robust devices with high yield. Here, we demonstrate an
+optimized process to realize high-performance field-effect transistor (FET)
+arrays from large-area (~5000 um2) monolayer MoS2 with a yield of 85 %. A
+central element of this process is an exposed material forming gas anneal
+(EM-FGA) that results in uniform FET performance metrics (i.e., field-effect
+mobilities, threshold voltages, and contact performance). Complementary
+analytical measurements show that the EM-FGA process reduces deleterious
+channel doping effects by decreasing organic contamination, while also reducing
+the prevalence of insulating molybdenum oxide, effectively improving the
+MoS2-gate oxide interface. The uniform FET performance metrics and high device
+yield achieved by applying the EM-FGA technique on large-area 2D material
+flakes will help advance the fabrication of complex 2D nanoelectronics devices
+and demonstrates the need for improved engineering of the 2D material-gate
+oxide interface.",1904.02189v1
+2019-08-05,Antioxidant capacity is repeatable across years but does not consistently correlate with a marker of peroxidation in a free-living passerine bird,"Oxidative stress occurs when reactive oxygen species (ROS) exceed antioxidant
+defences, which can have deleterious effects on cell function, health and
+survival. Therefore, organisms are expected to finely regulate pro-oxidant and
+antioxidant processes. ROS are mainly produced through aerobic metabolism and
+vary in response to changes in energetic requirements, whereas antioxidants may
+be enhanced, depleted or show no changes in response to changes in ROS levels.
+We investigated the repeatability, within-individual variation and correlation
+across different conditions of two plasmatic markers of the oxidative balance
+in 1108 samples from 635 free-living adult collared flycatchers (Ficedula
+albicollis). We sought to manipulate energy constraints by increasing wing load
+in 2012 and 2013 and by providing additional food in 2014. We then tested the
+relative importance of within- and between-individual variation on reactive
+oxygen metabolites (ROMs), a marker of lipid and protein peroxidation, and on
+non-enzymatic antioxidant defences (OXY test). We also investigated whether the
+experimental treatments modified the correlation between markers. Antioxidant
+defences were repeatable (range of repeatability estimates = 0.128--0.581),
+whereas ROMs were not (0--0.061). Antioxidants varied neither between
+incubation and nestling feeding nor between sexes. ROMs increased from
+incubation to nestling feeding in females and were higher in females than
+males. Antioxidant defences and ROM concentration were globally positively
+correlated, but the correlation varied between experimental conditions and
+between years. Hence, the management of oxidative balance in wild animals
+appears flexible under variable environmental conditions, an observation which
+should be confirmed over a wider range of markers.",1908.01488v1
+2019-11-29,Negative ionic states of tin in the oxide superconductor Sr$_{3-x}$SnO revealed by Mössbauer spectroscopy,"We report the temperature variation of the $^{119}$Sn-M\""{o}ssbauer spectra
+of the antiperovskite (inverse perovskite) oxide superconductor Sr$_{3-x}$SnO.
+Both superconductive (Sr-deficient) and non-superconductive (nearly
+stoichiometric) samples exhibit major $\gamma$-ray absorption with isomer shift
+similar to that of Mg$_2$Sn. This fact shows that Sr$_{3-x}$SnO contains the
+metallic anion Sn$^{4-}$, which is rare especially among oxides. In both
+samples, we observed another $\gamma$-ray absorption with a larger isomer
+shift, indicating that there is another ionic state of Sn with a higher
+oxidation number. The temperature dependence of the absorption intensities
+reveals that the Sn ions exhibiting larger isomer shifts have a lower energy of
+the local vibration. The larger isomer shift and lower vibration energy are
+consistent with the values estimated from the first-principles calculations for
+hypothetical structures with various Sr-deficiency arrangements. Therefore, we
+conclude that the additional $\gamma$-ray absorptions originate from the Sn
+atoms neighboring the Sr deficiency.",1911.12934v1
+2020-03-18,Pickling Behaviour of 2205 Duplex Stainless Steel Hot-rolled Strips in Sulfuric Acid Electrolytes,"Pickling behaviour of the oxide layer on hot-rolled 2205 duplex stainless
+steel (DSS) was studied in H2SO4 solutions with electrolytic workstation.",2003.08174v1
+2020-05-18,Strain-Induced Room-Temperature Ferroelectricity in SrTiO$_3$ Membranes,"Advances in complex oxide heteroepitaxy have highlighted the enormous
+potential of utilizing strain engineering via lattice mismatch to control
+ferroelectricity in thin-film heterostructures. This approach, however, lacks
+the ability to produce large and continuously variable strain states, thus
+limiting the potential for designing and tuning the desired properties of
+ferroelectric films. Here, we observe and explore dynamic strain-induced
+ferroelectricity in SrTiO$_3$ by laminating freestanding oxide films onto a
+stretchable polymer substrate. Using a combination of scanning probe
+microscopy, optical second harmonic generation measurements, and atomistic
+modeling, we demonstrate robust room-temperature ferroelectricity in SrTiO$_3$
+with 2.0% uniaxial tensile strain, corroborated by the notable features of
+180{\deg} ferroelectric domains and an extrapolated transition temperature of
+400 K. Our work reveals the enormous potential of employing oxide membranes to
+create and enhance ferroelectricity in environmentally benign lead-free oxides,
+which hold great promise for applications ranging from non-volatile memories
+and microwave electronics.",2005.09101v1
+2020-06-12,Probing Emergent Surface and Interfacial Properties in Complex Oxides via in situ X-ray Photoelectron Spectroscopy,"Emergent behavior at complex oxide interfaces has driven much of the research
+in the oxide thin film community for the past twenty years. Interfaces have
+been engineered for potential applications in spintronics, topological quantum
+computing, and high-speed electronics in cases where the bulk materials would
+not exhibit the desired properties. Advances in thin film growth have made the
+synthesis of these interfaces possible, while surface characterization tools
+such as X-ray photoelectron spectroscopy have been critical to understanding
+surface and interfacial phenomena in these materials. In this review we discuss
+the leading research in the oxide field over the past 5-10 years with a focus
+on connecting the key results to the X-ray photoelectron spectroscopy studies
+that enabled them. We describe how in situ integration of synthesis and
+spectroscopy can be used to improve the film growth process and to perform
+immediate experiments on specifically tailored interfacial heterostructures.
+These studies can include determination of interfacial intermixing, valence
+band alignment, and interfacial charge transfer. We also show how advances in
+synchrotron-based spectroscopy techniques have answered questions that cannot
+be addressed in a lab-based system. By further tying together synthesis and
+spectroscopy through in situ techniques, we conclude by discussing future
+opportunities in the field through the careful design of thin film
+heterostructures that are optimized for X-ray studies.",2006.07492v1
+2020-06-27,"Computational investigation of the plasmonic properties of TiN, ZrN, and HfN nanoparticles: The role of particle size, medium, and surface oxidation","Group 4 transition metal nitride (TMN) nanoparticles (NPs) display strong
+plasmonic responses in the visible and near-infrared regimes, exhibit high
+melting points and significant chemical stability and thus are potential
+earth-abundant alternatives to Au and Ag based plasmonic applications. However,
+a detailed understanding of the relationship between TMN NP properties and
+plasmonic response is required to maximize their utility. In this study, the
+localized surface plasmon resonance (LSPR) frequency, bandwidth, and extinction
+of titanium nitride (TiN), zirconium nitride (ZrN), and hafnium nitride (HfN)
+NPs were examined as a function of the particle size, surface oxidation, and
+refractive index of the surrounding medium using finite element method (FEM). A
+linear redshift in the LSPR frequency and a linear increase in the associated
+full-width at half maximum (FWHM) was observed with increasing the particle
+size, oxidation layer thickness, and medium refractive index. We show that the
+effect of surface oxidation on plasmonic properties of TMN NPs is strongly
+size-dependent with a significant LSPR redshift, intensity reduction, and
+broadening in small NPs compared to larger NPs. Furthermore, the performance
+and efficiency of HfN, ZrN, TiN as well as Au NPs for a narrowband application
+- photothermal therapy (PTT), and a broadband application - solar energy
+conversion, was investigated in detail. The results indicate that narrowband
+and broadband photothermal performance of NPs strongly depend on the particle
+size, surface properties and in case of narrowband absorption, excitation
+wavelength.",2006.15246v1
+2020-08-10,Extraordinarily Large Permittivity Modulation in Zinc Oxide for Dynamic Nanophotonics,"The dielectric permittivity of a material encapsulates the essential physics
+of light-matter interaction into the material's local response to optical
+excitation. Dynamic, photo-induced modulation of the permittivity can enable an
+unprecedented level of control over the phase, amplitude, and polarization of
+light. Therefore, the detailed dynamic characterization of technology-relevant
+materials with substantially tunable optical properties and fast response times
+is a crucial step in the realization of tunable optical devices. This work
+reports on the extraordinarily large permittivity changes in zinc oxide thin
+films (up to -3.6 relative change in the real part of the dielectric
+permittivity at 1600 nm wavelength) induced by optically generated free
+carriers. We demonstrate broadband reflectance modulation up to 70 percent in
+metal-backed oxide mirrors at the telecommunication wavelengths, with
+picosecond-scale relaxation times. The epsilon near zero points of the films
+can be dynamically shifted from 8.5 microns to 1.6 microns by controlling the
+pump fluence. Finally, we show that the modulation can be selectively enhanced
+at specific wavelengths employing metal-backed ZnO disks while maintaining
+picosecond-scale switching times. This work provides insights into the
+free-carrier assisted permittivity modulation in zinc oxide and could enable
+the realization of novel dynamic devices for beam-steering, polarizers, and
+spatial light modulators.",2008.03896v1
+2020-08-10,On-Stack Two-Dimensional Conversion of MoS2 into MoO3,"Chemical transformation of existing two-dimensional (2D) materials can be
+crucial in further expanding the 2D crystal palette required to realize various
+functional heterostructures. In this work, we demonstrate a 2D 'on-stack'
+chemical conversion of single-layer crystalline MoS2 into MoO3 with a precise
+layer control that enables truly 2D MoO3 and MoO3/MoS2 heterostructures. To
+minimize perturbation of the 2D morphology, a nonthermal oxidation using O2
+plasma was employed. The early stage of the reaction was characterized by a
+defect-induced Raman peak, drastic quenching of photoluminescence (PL) signals
+and sub-nm protrusions in atomic force microscopy images. As the reaction
+proceeded from the uppermost layer to the buried layers, PL and optical second
+harmonic generation signals showed characteristic modulations revealing a
+layer-by-layer conversion. The plasma-generated 2D oxides, confirmed as MoO3 by
+x-ray photoelectron spectroscopy, were found to be amorphous but extremely flat
+with a surface roughness of 0.18 nm, comparable to that of 1L MoS2. The rate of
+oxidation quantified by Raman spectroscopy decreased very rapidly for buried
+sulfide layers due to protection by the surface 2D oxides, exhibiting a
+pseudo-self-limiting behavior. As exemplified in this work, various on-stack
+chemical transformations can be applied to other 2D materials in forming
+otherwise unobtainable materials and complex heterostructures, thus expanding
+the palette of 2D material building blocks.",2008.03926v1
+2020-09-10,Solid-state Li-ion batteries operating at room temperature using new borohydride argyrodite electrolytes,"Using a new class of (BH4)- substituted argyrodite Li6PS5Z0.83(BH4)0.17, (Z =
+Cl, I) solid electrolyte, Li-metal solid-state batteries operating at room
+temperature have been developed. The cells were made by combining the modified
+argyrodite with an In-Li anode and two types of cathode: an oxide, LixMO2 (M =
+1/3Ni, 1/3Mn, 1/3Co; so called NMC) and a titanium disulfide, TiS2. The
+performance of the cells was evaluated through galvanostatic cycling and
+Alternating Current AC electrochemical impedance measurements. Reversible
+capacities were observed for both cathodes for at least tens of cycles.
+However, the high-voltage oxide cathode cell shows lower reversible capacity
+and larger fading upon cycling than the sulfide one. The AC impedance
+measurements revealed an increasing interfacial resistance at the cathode side
+for the oxide cathode inducing the capacity fading. This resistance was
+attributed to the intrinsic poor conductivity of NMC and interfacial reactions
+between the oxide material and the argyrodite electrolyte. On the contrary, the
+low interfacial resistance of the TiS2 cell during cycling evidences a better
+chemical compatibility between this active material and substituted
+argyrodites, allowing full cycling of the cathode material, 240 mAhg-1, for at
+least 35 cycles with a coulombic efficiency above 97%.",2009.04779v1
+2020-09-25,External control of GaN band bending using phosphonate self-assembled monolayers,"We report on the optoelectronic properties of GaN$(0001)$ and $(1\bar{1}00)$
+surfaces after their functionalization with phosphonic acid derivatives. To
+analyze the possible correlation between the acid's electronegativity and the
+GaN surface band bending, two types of phosphonic acids, n-octylphosphonic acid
+(OPA) and 1H,1H,2H,2H-perfluorooctanephosphonic acid (PFOPA), are grafted on
+oxidized GaN$(0001)$ and GaN$(1\bar{1}00)$ layers as well as on GaN nanowires.
+The resulting hybrid inorganic/organic heterostructures are investigated by
+X-ray photoemission and photoluminescence spectroscopy. The GaN work function
+is changed significantly by the grafting of phosphonic acids, evidencing the
+formation of dense self-assembled monolayers. Regardless of the GaN surface
+orientation, both types of phosphonic acids significantly impact the GaN
+surface band bending. A dependence on the acids' electronegativity is, however,
+only observed for the oxidized GaN$(1\bar{1}00)$ surface, indicating a
+relatively low density of surface states and a favorable band alignment between
+the surface oxide and acids' electronic states. Regarding the optical
+properties, the covalent bonding of PFOPA and OPA on oxidized GaN layers and
+nanowires significantly affect their external quantum efficiency, especially in
+the nanowire case due to the large surface-to-volume ratio. The variation in
+the external quantum efficiency is related to the modication of both the
+internal electric fields and surface states. These results demonstrate the
+potential of phosphonate chemistry for the surface functionalization of GaN,
+which could be exploited for selective sensing applications.",2009.12089v1
+2020-10-08,"Microstructure, mechanical properties, corrosion resistance and cytocompatibility of WE43 Mg alloy scaffolds fabricated by laser powder bed fusion for biomedical applications","Open-porous scaffolds of WE43 Mg alloy with a body-center cubic cell pattern
+were manufactured by laser powder bed fusion with different strut diameters.
+The geometry of the unit cells was adequately reproduced during additive
+manufacturing and the porosity within the struts was minimized. The
+microstructure of the scaffolds was modified by means of thermal solution and
+ageing heat treatments and was analysed in detail by means of X-ray
+microtomography, optical, scanning and transmission electron microscopy.
+Moreover, the corrosion rates and the mechanical properties of the scaffolds
+were measured as a function of the strut diameter and metallurgical condition.
+The microstructure of the as-printed scaffolds contained a mixture of Y-rich
+oxide particles and Rare Earth-rich intermetallic precipitates. The latter
+could be modified by heat treatments. The lowest corrosion rates of 2-3 mm/year
+were found in the as-printed and solution treated scaffolds and they could be
+reduced to ~0.1 mm/year by surface treatments using plasma electrolytic
+oxidation. The mechanical properties of the scaffolds improved with the strut
+diameter: the yield strength increased from 8 to 40 MPa and the elastic modulus
+improved from 0.2 to 0.8 GPa when the strut diameter increased from 275 \mu m
+to 800 \mu m. Nevertheless, the strength of the scaffolds without plasma
+electrolytic oxidation treatment decreased rapidly when immersed in simulated
+body fluid. In vitro biocompatibility tests showed surface treatments by plasma
+electrolytic oxidation were necessary to ensure cell proliferation in scaffolds
+with high surface-to-volume ratio.",2010.03812v1
+2020-10-12,Laser Assisted Solution Synthesis of High Performance Graphene Supported Electrocatalysts,"Simple, yet versatile, methods to functionalize graphene flakes with metal
+(oxide) nanoparticles are in demand, particularly for the development of
+advanced catalysts. Herein, based on light-induced electrochemistry, a
+laser-assisted, continuous, solution route for the simultaneous reduction and
+modification of graphene oxide with catalytic nanoparticles is reported.
+Electrochemical graphene oxide (EGO) is used as starting material and
+electron-hole pair source due to its low degree of oxidation, which imparts
+structural integrity and an ability to withstand photodegradation. Simply
+illuminating a solution stream containing EGO and metal salt (e.g., H2PtCl6 or
+RuCl3) with a 248 nm wavelength laser produces reduced EGO (rEGO, oxygen
+content 4.0 at%) flakes, decorated with Pt (~2.0 nm) or RuO2 (~2.8 nm)
+nanoparticles. The RuO2-rEGO flakes exhibit superior catalytic activity for the
+oxygen evolution reaction, requiring a small overpotential of 225 mV to reach a
+current density of 10 mA cm-2. The Pt-rEGO flakes (10.2 wt% of Pt) show
+enhanced mass activity for the hydrogen evolution reaction, and similar
+performance for oxygen reduction reaction compared to a commercial 20 wt% Pt/C
+catalyst. This simple production method is also used to deposit PtPd alloy and
+MnOx nanoparticles on rEGO, demonstrating its versatility in synthesizing
+functional nanoparticle-modified graphene materials.",2010.05556v1
+2020-10-16,Towards the surface hydroxyl species in CeO$_2$ nanoparticles,"Understanding the complex chemistry of functional nanomaterials is of
+fundamental importance. Controlled synthesis and characterization at the atomic
+level is essential to gain deeper insight into the unique chemical reactivity
+exhibited by many nanomaterials. Cerium oxide nanoparticles have many
+industrial and commercial applications,resulting from very strong catalytic,
+pro-and anti-oxidant activity. However, the identity of the active species and
+the chemical mechanisms imparted by nanoceria remain elusive, impeding the
+further development of new applications. Here, we explore the behavior of
+cerium oxide nanoparticles of different sizes at different temperatures and
+trace the electronic structure changes by state-of-the-art soft and hard X-ray
+experiments combined with computational methods. We confirm the absence of the
+Ce(III) oxidation state at the surface of CeO2nanoparticles, even for particles
+as small as 2 nm. Synchrotron X-ray absorption experiments at Ce L3and M5edges,
+combined with X-ray diffraction (XRD), high-resolution transmission electron
+microscopy (HRTEM) and small angle X-ray scattering (SAXS) and theoretical
+calculations demonstrate that in addition to the nanoceria charge stability,
+the formation of hydroxyl groups at the surface profoundly affects the chemical
+performance of these nanomaterials",2010.08206v1
+2020-11-02,Boron Nitride and Oxide Supported on Dendritic Fibrous Nanosilica for Catalytic Oxidative Dehydrogenation of Propane,"In this work, we were able to significantly increase the activity of boron
+nitride catalysts used for the oxidative dehydrogenation (ODH) of propane by
+designing and synthesising boron nitride (BN) supported on dendritic fibrous
+nanosilica (DFNS). DFNS/BN showed a markedly increased catalytic efficiency,
+accompanied by exceptional stability and selectivity. Textural characterisation
+together with solid-state NMR and X-ray photoelectron spectroscopic analyses
+indicate the presence of a combination of unique fibrous morphology of DFNS and
+various boron sites connected to silica to be the reason for this increase in
+the catalytic performance. Notably, DFNS/B${}_2$O${}_3$ also showed catalytic
+activity, although with more moderate selectivity compared to that of DFNS/BN.
+Solid-state NMR spectra indicates that the higher selectivity of DFNS/BN might
+stem from a larger amount of hydrogen-bonded hydroxyl groups attached to B
+atoms. This study indicates that both boron nitride and oxide are active
+catalysts and by using high surface area support (DFNS), conversion from
+propane to propene as well as productivity of olefins was significantly
+increased.",2011.00831v1
+2020-11-13,A physical method for investigating defect chemistry in solid metal oxides,"The investigation of the defect chemistry of solid oxides is of central
+importance for the understanding of redox processes. This can be performed by
+measuring conductivity as a function of the oxygen partial pressure, which is
+conventionally established by using buffer gas mixtures or oxygen pumps based
+on zirconia. However, this approach has some limitations, such as difficulty
+regulating oxygen partial pressure in some intermediate-pressure regions or the
+possibility of influencing the redox process by gases that can also be
+incorporated into the oxide or react with the surface via heterogeneous
+catalysis. Herein, we present an alternative physical method in which the
+oxygen partial pressure is controlled by dosing pure oxygen inside an
+ultra-high vacuum chamber. To monitor the conductivity of the oxide under
+investigation, we employ a dedicated four-probe measurement system that relies
+on the application of a very small AC voltage, in combination with lock-in data
+acquisition using highly sensitive electrometers, minimizing the
+electrochemical polarization or electro-reduction and degradation effects. By
+analyzing the model material SrTiO3, we demonstrate that its characteristic
+redox behavior can be reproduced in good agreement with the theory when
+performing simultaneous electrical conductivity relaxation (ECR) and
+high-temperature equilibrium conductivity (HTEC) measurements. We show that the
+use of pure oxygen allows for a direct analysis of the characteristic oxygen
+dose, which opens up various perspectives for a detailed analysis of the
+surface chemistry of redox processes.",2011.06877v1
+2020-11-26,A two-dimensional electron gas based on a 5s oxide with high room-temperature mobility and strain sensitivity,"The coupling of optical and electronic degrees of freedom together with
+quantum confinement in low-dimensional electron systems is particularly
+interesting for achieving exotic functionalities in strongly correlated oxide
+electronics. Recently, high room-temperature mobility has been achieved for a
+large bandgap transparent oxide - BaSnO$_3$ upon extrinsic La or Sb doping,
+which has excited significant research attention. In this work, we report the
+observation of room-temperature ferromagnetism in BaSnO$_3$ thin films and the
+realization of a two-dimensional electron gas (2DEG) on the surface of
+transparent BaSnO$_3$ via oxygen vacancy creation, which exhibits a high
+carrier density of $\sim 7.72*10^{14} /{\rm cm}^2$ and a high room-temperature
+mobility of ~18 cm$^2$/V/s. Such a 2DEG is rather sensitive to strain and a
+less than 0.1% in-plane biaxial compressive strain leads to a giant resistance
+enhancement of 350% (more than 540 kOhm/Square) at room temperature. Thus, this
+work creates a new path to exploring the physics of low-dimensional oxide
+electronics and devices applicable at room temperature.",2011.13106v2
+2020-11-25,Contrary Effect of B and N Doping into Graphene and Graphene Oxide Heterostructures with MoS$_2$ on Interface Function and Hydrogen Evolution,"Molybdenum disulfide (MoS$_2$) attracts attention as a high efficient and low
+cost photocatalyst for hydrogen production, but suffers from low conductance
+and high recombination rate of photo-generated charge carriers. In this work,
+we investigate the MoS$_2$ heterostructures with graphene variants (GVs),
+including graphene, graphene oxide, and their boron- and nitrogen-doped
+variants, by using first-principles calculations. Systematic comparison between
+graphene and graphene oxide composites is performed, and contrary effect of B
+and N doping on interface function and hydrogen evolution is clarified. We find
+that upon the formation of the interfaces some amount of electronic charge
+transfers from the GV side to the MoS$_2$ layer, inducing the creation of
+interface dipole and the reduction of work function, which is more pronounced
+in the graphene oxide composites. Moreover, our results reveal that N doping
+enhances the interface functions by forming donor-type interface states,
+whereas B doping reduces those functions by forming acceptor-type interface
+states. However, the B-doped systems exhibit lower Gibbs free energy difference
+for hydrogen adsorption on GV side than the N-doped systems, which deserves
+much consideration in the design of new functional photocatalysts.",2011.14000v1
+2021-02-12,Atomic scale mechanisms controlling the oxidation of polyethylene: a first principles study,"Understanding the degradation mechanisms of aliphatic polymers by thermal
+oxidation and radio-oxidation is very important in order to assess their
+lifetime in a variety of industrial applications. We focus here on polyethylene
+as a prototypical aliphatic polymer. Kinetic models describing the time
+evolution of the concentration of chain defects and radicals species in the
+material identify a relevant step in the formation and subsequent decomposition
+of transient hydroperoxides species, finally leading to carbonyl defects, in
+particular ketones. In this paper we first summarize the most relevant
+mechanistic paths proposed in the literature for hydroperoxide formation and
+decomposition and, second, revisit them using first principles calculations
+based on Density Functional Theory (DFT). We investigate the reaction paths for
+several chemical reactions, for both isolated alkane molecules and a
+crystalline model of polyethylene, and confirm, in some cases, the accepted
+activation energies; in some other cases, we challenge the accepted view
+finding alternative, more favourable, reaction paths for which we estimate the
+activation energy. We highlight the infuence of the environment -- crystalline
+or not -- on the outcome of some of the studied chemical reactions. A
+remarkable results of our calculations is that hydroxyl radicals play an
+important role in the decomposition of hydroperoxides. Based on our findings,
+it should be possible to improve the set of equations and parameters used in
+current kinetic simulations of polyethylene radio-oxidation.",2102.06397v2
+2021-02-16,Mesospheric nitric oxide model from SCIAMACHY data,"We present an empirical model for nitric oxide NO in the mesosphere
+($\approx$60--90 km) derived from SCIAMACHY (SCanning Imaging Absorption
+spectroMeter for Atmospheric CHartoghraphY) limb scan data. This work
+complements and extends the NOEM (Nitric Oxide Empirical Model; Marsh et al.,
+2004) and SANOMA (SMR Acquired Nitric Oxide Model Atmosphere; Kiviranta et al.,
+2018) empirical models in the lower thermosphere. The regression ansatz builds
+on the heritage of studies by Hendrickx et al. (2017) and the superposed epoch
+analysis by Sinnhuber et al. (2016) which estimate NO production from particle
+precipitation.
+  Our model relates the daily (longitudinally) averaged NO number densities
+from SCIAMACHY (Bender et al., 2017a, b) as a function of geomagnetic latitude
+to the solar Lyman-alpha and the geomagnetic AE (auroral electrojet) indices.
+We use a non-linear regression model, incorporating a finite and seasonally
+varying lifetime for the geomagnetically induced NO. We estimate the parameters
+by finding the maximum posterior probability and calculate the parameter
+uncertainties using Markov chain Monte Carlo sampling. In addition to providing
+an estimate of the NO content in the mesosphere, the regression coefficients
+indicate regions where certain processes dominate.",2102.08455v1
+2021-02-27,Ion-Beam Modification of Metastable Gallium Oxide Polymorphs,"Gallium oxide with a corundum structure ({\alpha}-Ga2O3) has recently
+attracted great attention in view of electronic and photonic applications due
+to its unique properties including a wide band gap exceeding that of the most
+stable beta phase (\b{eta}-Ga2O3). However, the lower thermal stability of the
+{\alpha}-phase at ambient conditions in comparison with the \b{eta}-phase
+requires careful investigation of its resistance to other external influences
+such as ion irradiation, ion doping, etc. In this work, the structural changes
+under the action of Al+ ion irradiation have been investigated for a
+polymorphic gallium oxide layers grown by hydride vapor phase epitaxy on
+c-plane sapphire and consisting predominantly of {\alpha}-phase with inclusions
+of {\alpha}(\k{appa})-phase. It is established by the X-ray diffraction
+technique that inclusions of {\alpha}(\k{appa})-phase in the irradiated layer
+undergo the expansion along the normal to the substrate surface, while there is
+no a noticeable deformation for the {\alpha}-phase. This speaks in favor of the
+different radiation tolerance of various Ga2O3 polymorphs, especially the
+higher radiation tolerance of the {\alpha}-phase. This fact should be taken
+into account when utilizing ion implantation to modify gallium oxide properties
+in terms of development of efficient doping strategies.",2103.00317v1
+2021-04-19,Bipolar conduction and giant positive magnetoresistance in doped metallic titanium oxide heterostructures,"Empowering conventional materials with unexpected magnetoelectric properties
+is appealing to the multi-functionalization of existing devices and the
+exploration of future electronics. Recently, owing to its unique effect in
+modulating a matter's properties, ultra-small dopants, e.g. H, D, and Li,
+attract enormous attention in creating emergent functionalities, such as
+superconductivity, and metal-insulator transition. Here, we report an
+observation of bipolar conduction accompanied by a giant positive
+magnetoresistance in D-doped metallic Ti oxide (TiOxDy) films. To overcome the
+challenges in intercalating the D into a crystalline oxide, a series of TiOxDy
+were formed by sequentially doping Ti with D and surface/interface oxidation.
+Intriguingly, while the electron mobility of the TiOxDy increases by an order
+of magnitude larger after doping, the emergent holes also exhibit high
+mobility. Moreover, the bipolar conduction induces a giant magnetoresistance up
+to 900% at 6 T, which is ~6 times higher than its conventional phase. Our study
+paves a way to empower conventional materials in existing electronics and
+induce novel electronic phases.",2104.09322v1
+2021-07-14,Electrical and Thermal Property of Si/GaAs Heterojunction Formed by Ultra-Thin Oxide Interfacial Layer,"We have successfully demonstrated Si/GaAs p-n heterostructures using Al2O3
+ultra-thin oxide interfacial layers. The band diagram and band offsets were
+investigated using X-ray photoelectron spectroscopy and confirm a small
+discontinuity in the conduction band (0.03 eV) at the interface. The interface
+defect density (Dit) values of the heterointerface with different ultra-thin
+oxide (UO) thicknesses ranged from 0.35 nm to 3.5 nm and were also
+characterized based on a metal-oxide-semiconductor capacitor (MOSCAP) structure
+using a capacitance-voltage measurement. The results revealed that a thin UO
+interfacial layer (around 1 nm) maximizes carrier transport property due to
+better surface passivation and efficient tunneling properties. Thermal property
+investigation also shows that the Al2O3 UO interfacial layer offers a good
+tunneling layer but also facilitates phonon transport across the interface.
+Finally, the electrical characterization of Si/GaAs heterojunction p-n diodes
+confirms reliable rectifying behavior with an extremely low ideality factor;
+thus, heterogeneous integration using the UO approach offers a robust way to
+create more types of heterojunctions between dissimilar semiconductors.",2107.06983v2
+2021-07-20,"The role of etching anisotropy in the fabrication of freestanding oxide microstructures on SrTiO3(100), SrTiO3(110), and SrTiO3(111) substrates","The release process for the fabrication of freestanding oxide microstructures
+relies on appropriate, controllable and repeatable wet etching procedures.
+SrTiO3 is among the most employed substrates for oxide thin films growth and
+can be decomposed in HF:water solution. Such process is strongly anisotropic
+and is affected by local defects and substrate cut-plane. We analyze the
+etching behavior of SrTiO3 substrates having (100), (110), and (111) cut-planes
+during immersion in a 5% HF:water solution. The etching process over the three
+substrates is compared in terms of pitting, anisotropy, macroscopic etch rate
+and underetching effects around HF-resistant (La,Sr)MnO3 thin film
+micropatterns. The release of targeted structures, such as the reported
+(La,Sr)MnO3 freestanding microbridges, depends on the substrate
+crystallographic symmetry and on the in-plane orientation of the structures
+themselves along the planar directions. By comparing the etching evolution at
+two different length scales, we distinguish two regimes for the propagation of
+the etching front: an intrinsic one, owning to a specific lattice direction,
+and a macroscopic one, resulting from the mixing of different etching fronts.
+We report the morphologies of the etched SrTiO3 surfaces and the geometries of
+the underetched regions as well as of the microbridge clamping zones. The
+reported analysis will enable the design of complex MEMS devices by allowing to
+model the evolution of the etching process required for the release of
+arbitrary structures made of oxide thin films deposited on top of STO.",2107.09441v1
+2021-09-23,Observation of metallic electronic structure in a single-atomic-layer oxide,"Correlated electrons in transition metal oxides (TMOs) exhibit a variety of
+emergent phases. When TMOs are confined to a single-atomic-layer thickness,
+experiments so far have shown that they usually lose diverse properties and
+become insulators. In an attempt to extend the range of electronic phases of
+the single-atomic-layer oxide, we search for a metallic phase in a
+monolayer-thick epitaxial SrRuO$_3$ film. Combining atomic-scale epitaxy and
+angle-resolved photoemission measurements, we show that the monolayer SrRuO$_3$
+is a strongly correlated metal. Systematic investigation reveals that the
+interplay between dimensionality and electronic correlation makes the monolayer
+SrRuO$_3$ an incoherent metal with orbital-selective correlation. Furthermore,
+the unique electronic phase of the monolayer SrRuO$_3$ is found to be highly
+tunable, as charge modulation demonstrates an incoherent-to-coherent crossover
+of the two-dimensional metal. Our work emphasizes the potentially rich phases
+of single-atomic-layer oxides and provides a guide to the manipulation of their
+two-dimensional correlated electron systems.",2109.11090v1
+2021-09-29,An Idealised Approach of Geometry and Topology to the Diffusion of Cations in Honeycomb Layered Oxide Frameworks,"Honeycomb layered oxides are a novel class of nanostructured materials
+comprising alkali or alkaline earth metals intercalated into transition metal
+slabs. The intricate honeycomb architecture and layered framework endows this
+family of oxides with a tessellation of features such as exquisite
+electrochemistry, unique topology and fascinating electromagnetic phenomena.
+Despite having innumerable functionalities, these materials remain highly
+underutilized as their underlying atomistic mechanisms are vastly unexplored.
+Therefore, in a bid to provide a more in-depth perspective, we propose an
+idealised diffusion model of the charged alkali cations (such as lithium,
+sodium or potassium) in the two-dimensional (2D) honeycomb layers within the
+three-dimensional (3D) crystal of honeycomb layered oxide frameworks. This
+model not only explains the correlation between the excitation of cationic
+vacancies (by applied electromagnetic fields) and the Gaussian curvature
+deformation of the 2D surface, but also takes into consideration, the quantum
+properties of the cations and their inter-layer mixing through quantum
+tunnelling. Through this work, we offer a novel theoretical framework for the
+study of 3D layered materials with 2D cationic diffusion currents, as well as
+providing pedagogical insights into the role of topological phase transitions
+in these materials in relation to Brownian motion and quantum geometry.",2109.14679v1
+2021-10-19,Generalized estimates for the density of oxide scale in the range from 0 C to 1300 C,"Oxide scale formed on the surface of steel products during high-teperature
+processes is studied as a composite material, the main solid components of
+which, in general, are wustite, magnetite, hematite and metallic iron. To
+estimate the density of each of these components in the temperature range from
+0 C to 1300 C, formulas are proposed that are consistent with the empirical
+functions of the coefficient of linear thermal expansion, which the authors
+obtained earlier by generaizing data from open sources. The Curie and
+polymorphic transformation temperatures are included in these generalized
+formulas as variable parameters, which allows one to take into account the
+movability of phase transitions due to impurities, crystal lattice defects,
+particle sizes, cooling rate, and other factors. When specifying the particular
+values of critical temperatures, the other parameters of the formulas are
+recalculated automatically. In a particular form, the proposed formulas
+correspond to the basic values of critical temperatures. According to the
+calculation examples given, the true (not including pores) density of oxide
+scale can be about 5200 to 5600 kg/m3, depending on the temperature and
+percentage of components, whereby a local density minimum may be observed in
+the region of 570 C due to eutectoid decomposition of wustite into magnetite
+and iron. The proposed methods are recommended for use in mathematical
+simulation of processing of steel products in the presence of oxide scale on
+its surface.",2110.09791v1
+2021-12-01,Oxygen and Aluminum-Magnesium Isotopic Systematics of Presolar Nanospinel Grains from CI Chondrite Orgueil,"Presolar oxide grains have been previously divided into several groups (Group
+1 to 4) based on their isotopic compositions, which can be tied to several
+stellar sources. Much of available data was acquired on large grains, which may
+not be fully representative of the presolar grain population present in
+meteorites. We present here new O isotopic data for 74 small presolar oxide
+grains (~200 nm in diameter on average) from Orgueil and Al-Mg isotopic
+systematics for 25 of the grains. Based on data-model comparisons, we show that
+(i) Group 1 and Group 2 grains more likely originated in low-mass first-ascent
+(red giant branch; RGB) and/or second-ascent (asymptotic giant branch; AGB) red
+giant stars and (ii) Group 1 grains with (26Al/27Al)0 >= 5x10^-3 and Group 2
+grains with (26Al/27Al)0 <= 1x10^-2 all likely experienced extra circulation
+processes in their parent low-mass stars but under different conditions,
+resulting in proton-capture reactions occurring at enhanced temperatures. We do
+not find any large 25Mg excess in Group 1 oxide grains with large 17O
+enrichments, which provides evidence that 25Mg is not abundantly produced in
+low-mass stars. We also find that our samples contain a larger proportion of
+Group 4 grains than so far suggested in the literature for larger presolar
+oxide grains (~400 nm). We also discuss our observations in the light of
+stellar dust production mechanisms.",2112.00512v1
+2021-12-09,Comparative studies of hydrogen dissolution and release behavior in zirconate oxides by TDS and TMAP4 analysis,"Proton-conducting oxides are potential materials for electrochemical devices
+such as fuel cells, hydrogen pumps, hydrogen sensors, and the tritium
+purification and recovery system in nuclear fusion reactors. The hydrogen
+concentration in oxide materials is important, but its precise measurement is
+difficult. In this study, thermal desorption spectroscopy (TDS) was used to
+investigate hydrogen dissolution and release behavior in proton-conducting
+oxides, yttrium (Y), and cobalt (Co) doped barium-zirconates in the temperature
+range of 673-1273 K using deuterium (D2) and heavy water (D2O). Specimens were
+prepared with conventional powder metallurgy: the powder of three zirconates,
+BaZr0.9Y0.1O3-a (BZY), BaZr0.955Y0.03Co0.015O3-a (BZYC), and CaZr0.9In0.1O2.95
+(CZI) was pressed into discs and fired in the air at 1873 K for 20 h. The
+densities of the sintered BZY, BZYC, and CZI specimens were 98 percent, 99.7
+percent, and 99.5 percent of the theoretical densities respectively. XRD, SEM,
+and EDX were performed for the structural and morphological analysis of the
+sintered samples. From TDS measurement, a similar trend of
+temperature-dependent hydrogen solubility was obtained for all samples compared
+to the tritium imaging plate (TIP) methods literature data of HT- and
+DTO-exposed samples. To compare the experimental results of the deuterium
+desorption profile derived by TDS analysis, the simulation code of the tritium
+migration analysis program, version 4 (TMAP4) was employed.",2112.04649v1
+2021-12-18,Nitrogen incorporated Zinc oxide thin film for efficient ethanol detection,"Zinc oxide which is a n-type semiconducting metal oxide (SMO) has been a
+promising material for detecting ethanol vapor. However, pure ZnO based ethanol
+sensors often suffer from high working temperature, cross sensitivity towards
+methanol and poor stability against humidity. Doping ZnO with various metal
+ions has been widely explored as a proficient approach to improve its ethanol
+sensing properties, while anionic dopants have been rarely considered. Here in
+we demonstrate the effect of nitrogen doping on the ethanol sensing
+characteristics of ZnO thin films. Nitrogen doped ZnO (N-ZnO) thin films have
+been synthesized following sol-gel technique with urea as nitrogen precursor.
+Ethanol sensing characteristics of the N-ZnO thin film has been com-pared with
+pure ZnO sensor over a wide range of temperature and relative humidity
+conditions. The N-ZnO sensor exhibits significantly large ethanol sensing
+response at a lower operating temperature (~99 % at 225 {\deg}C vs ~81 % at 250
+{\deg}C for ZnO), faster response time (12 s vs 33 s for ZnO), long term
+stability, improved resilience against humidity and selectivity towards ethanol
+over methanol and acetone. The experimental observations have been supplemented
+by estimating the adsorption energies of ethanol on ZnO and N-ZnO surface using
+density functional theory (DFT) calculations. We discuss that the microscopic
+origin of improved ethanol sensing of N-ZnO is related to the facile adsorption
+of ethanol molecules on the oxide surface which is promoted by modification of
+electronic properties of ZnO by the nitrogen dopant atoms.",2112.09889v1
+2022-02-22,Giant spin torque efficiency in naturally oxidized polycrystalline TaAs thin films,"We report the measurement of efficient charge-to-spin conversion at room
+temperature in Weyl semimetal/ferromagnet heterostructures with both oxidized
+and pristine interfaces. Polycrystalline films of the Weyl semimetal, TaAs, are
+grown by molecular beam epitaxy on (001) GaAs and interfaced with a metallic
+ferromagnet (Ni$_{0.8}$Fe$_{0.2}$). Spin torque ferromagnetic resonance
+(ST-FMR) measurements in samples with an oxidized interface yield a spin torque
+efficiency as large as $\xi_{\mathrm{FMR}}=0.45\pm 0.25$ for a 8 nm
+Ni$_{0.8}$Fe$_{0.2}$ layer thickness. By studying ST-FMR in these samples with
+varying Ni$_{0.8}$Fe$_{0.2}$ layer thickness, we extract a damping-like torque
+efficiency as high as $\xi_{\mathrm{DL}}=1.36\pm 0.66$. In samples with a
+pristine (unoxidized) interface, the spin torque efficiency has opposite sign
+to that observed in oxidized samples ($\xi_{\mathrm{FMR}}=-0.27\pm 0.14$ for a
+5 nm Ni$_{0.8}$Fe$_{0.2}$ layer thickness). We also find a lower bound on the
+spin Hall conductivity ($424 \pm 110 \frac{\hbar}{e}$ S/cm) which is
+surprisingly consistent with theoretical predictions for the single crystal
+Weyl semimetal state of TaAs.",2202.10656v1
+2022-02-22,Toward Functionalized Ultrathin Oxide Films: the Impact of Surface Apical Oxygen,"Thin films of transition metal oxides open up a gateway to nanoscale
+electronic devices beyond silicon characterized by novel electronic
+functionalities. While such films are commonly prepared in an oxygen
+atmosphere, they are typically considered to be ideally terminated with the
+stoichiometric composition. Using the prototypical correlated metal SrVO$_3$ as
+an example, it is demonstrated that this idealized description overlooks an
+essential ingredient: oxygen adsorbing at the surface apical sites. The oxygen
+adatoms, which persist even in an ultrahigh vacuum environment, are shown to
+severely affect the intrinsic electronic structure of a transition metal oxide
+film. Their presence leads to the formation of an electronically dead surface
+layer but also alters the band filling and the electron correlations in the
+thin films. These findings highlight that it is important to take into account
+surface apical oxygen or -- mutatis mutandis -- the specific oxygen
+configuration imposed by a capping layer to predict the behavior of ultrathin
+films of transition metal oxides near the single unit-cell limit.",2202.10778v1
+2022-03-14,Emergent dynamics in an astrocyte-neuronal network coupled via nitric oxide,"In the brain, both neurons and glial cells work in conjunction with each
+other during information processing. Stimulation of neurons can cause calcium
+oscillations in astrocytes which in turn can affect neuronal calcium dynamics.
+The ""glissandi"" effect is one such phenomenon, associated with a decrease in
+infraslow fluctuations, in which synchronized calcium oscillations propagate as
+a wave in hundreds of astrocytes. Nitric oxide molecules released from the
+astrocytes contribute to synaptic functions on the basis of the underlying
+astrocyte-neuron interaction network. In this study, by defining an
+astrocyte-neuronal (A-N) unit as an integrated circuit of one neuron and one
+astrocyte, we developed a minimal model of neuronal stimulus-dependent and
+nitric oxide-mediated emergence of calcium waves in astrocytes. Incorporating
+inter-unit communication via nitric oxide molecules, a coupled network of 1,000
+such A-N units is developed in which multiple stable regimes were found to
+emerge in astrocytes. We examined the ranges of neuronal stimulus strength and
+the coupling strength between A-N units that give rise to such dynamical
+behaviors. We also report that there exists a range of coupling strength,
+wherein units not receiving stimulus also start showing oscillations and become
+synchronized. Our results support the hypothesis that glissandi-like phenomena
+exhibiting synchronized calcium oscillations in astrocytes help in efficient
+synaptic transmission by reducing the energy demand of the process.",2203.07193v1
+2022-03-26,Tailoring the Thickness-Dependent Optical Properties of Conducting Nitrides and Oxides for Epsilon-Near-Zero-Enhanced Photonic Applications,"The unique properties of the emerging photonic materials - conducting
+nitrides and oxides - especially their tailorability, large damage thresholds,
+and the so-called epsilon-near-zero (ENZ) behavior, have enabled novel photonic
+phenomena spanning optical circuitry, tunable metasurfaces, and nonlinear
+optical devices. This work explores direct control of the optical properties of
+polycrystalline titanium nitride (TiN) and aluminum-doped zinc oxide (AZO) by
+tailoring the film thickness, and their potential for ENZ-enhanced photonic
+applications. We demonstrate that TiN-AZO bilayers act as Ferrell-Berreman
+metasurfaces with thickness-tailorable epsilon-near-zero resonances in the AZO
+films operating in the telecom wavelengths spanning from 1470 to 1750 nm. The
+bilayer stacks also act as strong light absorbers in the ultraviolet regime
+employing the radiative ENZ modes and the Fabry-Perot modes in the constituent
+TiN films. The studied Berreman metasurfaces exhibit optically-induced
+reflectance modulation of 15% with picosecond response-time. Together with the
+optical response tailorability of conducting oxides and nitrides, utilizing the
+field-enhancement near the tunable ENZ regime could enable a wide range of
+nonlinear optical phenomena, including all-optical switching, time refraction,
+and high-harmonic generation.",2203.14170v1
+2022-04-07,Graphene oxide 2D films integrated with nanowires and ring resonators for enhanced nonlinear optics,"We report enhanced nonlinear optics in nanowires, waveguides, and ring
+resonators by introducing layered two-dimensional (2D) graphene oxide (GO)
+films through experimental demonstration. The GO films are integrated on
+silicon-on-insulator nanowires (SOI), high index doped silica glass, and
+silicon nitride (SiN) waveguides and microring resonators (MRRs), to
+demonstrate an improved optical nonlinearity including Kerr nonlinearity and
+four-wave mixing (FWM). By using a large-area, transfer-free, layer-by-layer GO
+coating method with photolithography and lift-off processes, we integrate GO
+films on these complementary metal-oxide-semiconductor (CMOS)-compatible
+devices. For SOI nanowires, significant spectral broadening of optical pulses
+in GO-coated SOI nanowires induced by self-phase modulation (SPM) is observed,
+achieving a high spectral broadening factor of 4.34 for a device with a
+patterned film including 10 layers of GO. A significant enhancement in the
+nonlinear figure of merit (FOM) for silicon nanowires by a factor of 20 is also
+achieved, resulting in a FOM > 5. For Hydex and SiN waveguides, enhanced FWM in
+the GO-coated waveguides is achieved, where conversion efficiency (CE)
+enhancements of up to 6.9 dB and 9.1 dB relative to the uncoated waveguides.
+For MRRs, an increase of up to ~10.3 dB in the FWM CE is achieved due to the
+resonant enhancement effect. These results reveal the strong potential of GO
+films to improve the nonlinear optics of nanowires, waveguides, and ring
+resonators.",2204.03184v1
+2022-04-14,Non-equilibrium Phonon Thermal Resistance at MoS2/Oxide and Graphene/Oxide Interfaces,"Accurate measurements and physical understanding of thermal boundary
+resistance (R) of two-dimensional (2D) materials are imperative for effective
+thermal management of 2D electronics and photonics. In previous studies, heat
+dissipation from 2D material devices was presumed to be dominated by phonon
+transport across the interfaces. In this study, we find that in addition to
+phonon transport, thermal resistance between non-equilibrium phonons in the 2D
+materials could play a critical role too when the 2D material devices are
+internally self-heated, either optically or electrically. We accurately measure
+R of oxide/MoS2/oxide and oxide/graphene/oxide interfaces for three oxides
+(SiO2, HfO2, Al2O3) by differential time-domain thermoreflectance (TDTR). Our
+measurements of R across these interfaces with external heating are 2-to-4
+times lower than previously reported R of the similar interfaces measured by
+Raman thermometry with internal self-heating. Using a simple model, we show
+that the observed discrepancy can be explained by an additional internal
+thermal resistance (Rint) between non-equilibrium phonons present during Raman
+measurements. We subsequently estimate that for MoS2 and graphene, Rint is
+about 31 and 22 m2 K/GW, respectively. The values are comparable to the thermal
+resistance due to finite phonon transmission across interfaces of 2D materials
+and thus cannot be ignored in the design of 2D material devices. Moreover, the
+non-equilibrium phonons also lead to a different temperature dependence than
+that by phonon transport. As such, our work provides important insights into
+physical understanding of heat dissipation in 2D material devices.",2204.06975v1
+2022-04-22,Versatile coating platform for metal oxide nanoparticles: applications to materials and biological science,"In this feature article, we provide an overview of our research on
+statistical copolymers as a coating material for metal oxide nanoparticles and
+surfaces. These copolymers contain functional groups enabling non-covalent
+binding to oxide surfaces and poly(ethylene glycol) (PEG) polymers for
+colloidal stability and stealthiness. The functional groups are organic
+derivatives of phosphorous acid compounds R-H$_2$PO$_3$, also known as
+phosphonic acids that have been screened for their strong affinity to metals
+and their ability to build multidentate binding. Herein we develop a
+polymer-based coating platform that shares features with the techniques of
+self-assembled monolayers (SAM) and Layer-by-Layer (L-b-L) deposition. The
+milestones of this endeavor are the synthesis of PEG-based copolymers
+containing multiple phosphonic acid groups, the implementation of simple
+protocols combining versatility with high particle production yields and the
+experimental demonstration of the colloidal stability of the coated particles.
+As a demonstration, coating studies are conducted on cerium (CeO$_2$), iron
+($\gamma$-Fe$_2$O$_3$), aluminum (Al$_2$O$_3$) and titanium (TiO$_2$) oxides of
+different sizes and morphologies. We finally discuss applications in the domain
+of nanomaterials and nanomedicine. We evaluate the beneficial effects of
+coating on redispersible nanopowders, contrast agents for In Vitro/Vivo assays
+and stimuli-responsive particles.",2204.10547v2
+2022-04-30,A Nanometer-Thick Oxide Semiconductor Transistor with Ultra-High Drain Current,"High drive current is a critical performance parameter in semiconductor
+devices for high-speed, low-power logic applications or high-efficiency,
+high-power, high-speed radio frequency (RF) analog applications. In this work,
+we demonstrate an In2O3 transistor grown by atomic layer deposition (ALD) at
+back-end-of-line (BEOL) compatible temperatures with a record high drain
+current exceeding 10 A/mm, the performance of which is 2-3 times better than
+all known transistors with semiconductor channels. A record high
+transconductance of 4 S/mm is also achieved among all transistors with a planar
+structure. It is found that a high carrier density and high electron velocity
+both contribute to this remarkably high on-state performance in ALD In2O3
+transistors, which is made possible by the high-quality oxide/oxide interface,
+the metal-like charge-neutrality-level (CNL) alignment, and the high band
+velocities induced by the low density-of-state (DOS). Experimental Hall, I-V
+and split C-V measurements at room temperature confirm a high carrier density
+up to 6-7*10^13 /cm2 and a high velocity of about 10^7 cm/s. Ultra-thin oxide
+semiconductors, with a CNL located deep inside the conduction band, represent a
+promising new direction for the search of alternative channel materials for
+high-performance semiconductor devices.",2205.00357v1
+2022-07-04,Electrically switchable Casimir forces using transparent conductive oxides,"Casimir forces between charge-neutral bodies originate from quantum vacuum
+fluctuations of electromagnetic fields, which exhibit a critical dependence on
+material's electromagnetic properties. Over the years, in-situ modulation of
+material's optical properties has been enabled through various means and has
+been widely exploited in a plethora of applications such as electro-optical
+modulation, transient color generation, bio- or chemical sensing, etc. Yet
+Casimir force modulation has been hindered by difficulty in achieving high
+modulation signals due to the broadband nature of the Casimir interaction. Here
+we propose and investigate two configurations that allow for in-situ modulation
+of Casimir forces through electrical gating of a metal-insulator-semiconductor
+(MIS) junction comprised of transparent conductive oxide (TCO) materials. By
+switching the gate voltage on and off, a force modulation of > 400 pN is
+predicted due to substantive charge carrier accumulation in the TCO layer,
+which can be easily measured using state-of-the-art force measurement
+techniques in an atomic force microscope (AFM). We further examine the
+influence of the oxide layer thickness on the force modulation, suggesting the
+importance of the fine control of the oxide layer deposition. Our work provides
+a promising pathway for modulating the Casimir effect in-situ with
+experimentally measurable force contrast.",2207.02305v1
+2022-07-08,High-speed laser writing of structural colors for full-color inkless printing,"It is a formidable challenge to simultaneously achieve wide gamut, high
+resolution, high-speed while low-cost manufacturability, long-term stability,
+and viewing-angle independence in structural colors for practical applications.
+The conventional nanofabrication techniques fail to match the requirement in
+low-cost, large-scale and flexible manufacturing. Processing by ultrashort
+lasers can achieve extremely high throughput while suffering from a narrow
+gamut of 15% sRGB or angle-dependent colors. Here, we demonstrate an all-in-one
+solution for ultrafast laser-produced structural colors on ultrathin hybrid
+films that comprise an absorbent TiAlN layer coating on a metallic TiN layer.
+Under pulsed laser irradiation, the absorption behaviors of the TiAlN-TiN
+hybrid films are tailored by photothermal-induced oxidation on the topmost
+TiAlN. The oxidized films exhibit double-resonance absorption, which is
+attributed to the non-trivial phase shifts both at the oxide-TiAlN interface,
+and at the TiAlN-TiN interface. By varying the accumulated laser fluence to
+modulate the oxidation depth, an unprecedented large gamut of 90% sRGB is
+obtained. Our highly reproducible printing technique manifests
+angle-insensitive colors the variation of Hue is <0.14pi when viewing angles
+changing from 6 to 60. The full-color printing speed reaches to 1.4 cm2/s and
+the highest printing resolution exceeds 25000 dpi. The durability of the
+laser-printed colors is confirmed by fastness examination, including salt fog,
+double-85, light bleaching, and adhesion tests. These features render our
+technique to be competitive for high-throughput industrial applications.",2207.03649v1
+2022-07-14,Magnetron Sputtered Non-Toxic and Precious Element-Free Ti-Zr-Ge Metallic Glass Nanofilms with Enhanced Biocorrosion Resistance,"The chemical composition and structural state of advanced alloys are the
+decisive factors in optimum biomedical performance. This contribution presents
+unique Ti-Zr-Ge metallic glass thin-film compositions fabricated by magnetron
+sputter deposition targeted for nanocoatings for biofouling prevention. The
+amorphous nanofilms with nanoscale roughness exhibit a large relaxation and
+supercooled liquid regions as revealed by flash differential scanning
+calorimetry. Ti\textsubscript{68}Zr\textsubscript{8}Ge\textsubscript{24} shows
+the lowest corrosion (0.17 \textmu A cm\textsuperscript{\textminus2}) and
+passivation (1.22 \textmu A cm\textsuperscript{\textminus2}) current densities,
+with the lowest corrosion potential of \textminus0.648 V and long-range
+stability against pitting, corroborating its excellent performance in phosphate
+buffer solution at 37 {\textdegree}C. The oxide layer is comprised of
+TiO\textsubscript{2}, TiO\textsubscript{\emph{x}} and
+ZrO\textsubscript{\emph{x}}, as determined using X-ray photoelectron
+spectroscopy by short-term ion-etching of the surface layer. The two orders of
+magnitude increase in the oxide and interface resistance (from 14 to 1257
+{\textOmega} cm\textsuperscript{2}) along with an order of magnitude decrease
+in the capacitance parameter of the oxide interface (from 1.402 x
+10\textsuperscript{\textminus5} to 1.677 x 10\textsuperscript{\textminus6} S
+s\textsuperscript{n} cm\textsuperscript{\textminus2}) of the same composition
+is linked to the formation of carbonyl groups and reduction of the native oxide
+layer during linear sweep voltammetry.",2207.07000v2
+2022-07-28,Resolving oxidation states and Sn-halide interactions of perovskites through Auger parameter analysis in XPS,"Reliable chemical state analysis of Sn semiconductors by XPS is hindered by
+the marginal observed shift in the Sn 3d region. For hybrid Sn-based
+perovskites especially, errors associated with charge referencing can easily
+exceed chemistry-related shifts. Studies based on the modified Auger parameter
+${\alpha}'$ provide a suitable alternative and have been used previously to
+resolve different chemical states in Sn alloys and oxides. However, the
+meaningful interpretation of Auger parameter variations on Sn-based perovskite
+semiconductors requires fundamental studies. In this work, we perform a
+comprehensive Auger parameter study through systematic compositional variations
+of Sn halide perovskites. We find that in addition to the oxidation state,
+${\alpha}'$ is highly sensitivity to the composition of the halide-site,
+inducing shifts of up to ${\Delta}{\alpha}' = 2 eV$ between ASnI$_3$ and
+ASnBr$_3$ type perovskites. The reported dependencies of ${\alpha}'$ on the Sn
+oxidation state, coordination and local chemistry provide a framework that
+enables reliable tracking of degradation as well as X-site interaction for
+Sn-based perovskites and related compounds. The higher robustness and
+sensitivity of such studies not only enables more in-depth surface analysis of
+Sn-based perovskites than previously performed, but also increases
+reproducibility across laboratories.",2207.14123v1
+2022-07-29,"Selective Laser Reaction Synthesis of SiC, Si$_3$N$_4$ and HfC/SiC Composites for Additive Manufacturing","Selective laser reaction sintering techniques (SLRS) techniques were
+investigated for the production of near net-shape non-oxide ceramics including
+SiC, Si$_3$N$_4$, and HfC/SiC composites that might be compatible with
+prevailing powder bed fusion additive manufacturing processes. Reaction bonded
+layers of covalent ceramics were produced using in-situ reactions that occur
+during selective laser processing and layer formation. During SLRS, precursor
+materials composed of metal and/or metal oxide powders were fashioned into
+powder beds for conversion to non-oxide ceramic layers. Laser-processing was
+used to initiate simultaneous chemical conversion and local interparticle
+bonding of precursor particles in CH4 or NH3 gases. Several factors related to
+the reaction synthesis process (precursor chemistry, gas-solid and gas-liquid
+synthesis mechanisms, precursor vapor pressures) were investigated in relation
+to resulting microstructures and non-oxide yields. Results indicated that the
+volumetric changes which occurred during in-situ conversion of single component
+precursors negatively impacted the surface layer microstructure. To circumvent
+the internal stresses and cracking that accompanied the conversion of Si or Hf
+(that expands upon conversion) or SiO$_x$ (that contracts during conversion),
+optimized ratios of the precursor constituents were used to produce near
+isovolumetric conversion to the product phase. The results demonstrate that
+under appropriate processing conditions and precursor selection, the formation
+of near net-shape SiC and SiC composites might be achieved through single-step
+AM-compatible techniques.",2208.00054v1
+2022-08-12,The effect of ambient air pollution on birth outcomes in Norway,"Ambient air pollution is harmful to the fetus even in countries with
+relatively low levels of pollution. In this paper, I examine the effects of
+ambient air pollution on birth outcomes in Norway. I find that prenatal
+exposure to ambient nitric oxide in the last trimester causes significant birth
+weight and birth length loss under the same sub-postcode fixed effects and
+calendar month fixed effects, whereas other ambient air pollutants such as
+nitrogen dioxide and sulfur dioxide appear to be at safe levels for the fetus
+in Norway. In addition, the marginal adverse effect of ambient nitric oxide is
+larger for newborns with disadvantaged parents. Both average concentrations of
+nitric oxide and occasional high concentration events can adversely affect
+birth outcomes. The contributions of my work include: first, my finding that
+prenatal exposure to environmental nitric oxide has an adverse effect on birth
+outcomes fills a long-standing knowledge gap. Second, with the large sample
+size and geographic division of sub-postal codes in Norway, I can control for a
+rich set of spatio-temporal fixed effects to overcome most of the endogeneity
+problems caused by the choice of residential area and date of delivery. In
+addition, I study ambient air pollution in a low-pollution setting, which
+provides new evidence on the health effects of low ambient air pollution.",2208.06271v6
+2022-09-19,Resolving diverse oxygen transport pathways across Sr-doped lanthanum ferrite and metal-perovskite heterostructures,"Perovskite structured transition metal oxides are important technological
+materials for catalysis and solid oxide fuel cell applications. Their
+functionality often depends on oxygen diffusivity and mobility through complex
+oxide heterostructures, which can be significantly impacted by structural and
+chemical modifications, such as doping. Further, when utilized within
+electrochemical cells, interfacial reactions with other components (e.g. Ni-
+and Cr-based alloy electrodes and interconnects) can influence the perovskite's
+reactivity and ion transport, leading to complex dependencies that are
+difficult to control in real-world environments. Here we use isotopic tracers
+and atom probe tomography to directly visualize oxygen diffusion and transport
+pathways across perovskite and metal-perovskite heterostructures, i.e. (Ni-Cr
+coated) Sr-doped lanthanum ferrite (LSFO). Annealing in 18O2(g) results in
+elemental and isotopic redistributions through oxygen exchange (OE) in the LSFO
+while Ni-Cr undergoes oxidation via multiple mechanisms and transport pathways.
+Complementary density functional theory (DFT) calculations at experimental
+conditions provide rationale for OE reaction mechanisms and reveal a complex
+interplay of different thermodynamic and kinetic drivers. Our results shed
+light on the fundamental coupling of defects and oxygen transport in an
+important class of catalytic materials.",2209.09302v1
+2022-09-26,Molecular filtration by reduced graphene oxide sandwiched between wood sheets,"This study investigates the prospect of using reduced graphene oxide
+encapsulated between thin wood membranes as a composite filter for water
+filtration. Graphene oxide (GO) with a volume range of 0.2 to 0.5 mL was
+deposited on a 95 mm2 area of thin sheets of Balsa wood with a thickness range
+of 2.20 - 3.50 mm. The dried GO deposits were laser treated in reduced oxygen
+environment to prepare a reduced graphene oxide-wood composite (rGO-wood). The
+rGO substrate of the composite was sandwiched between 2 wood sheets which were
+glued using polydimethylsiloxane (PDMS) to give a stable membrane. Fabricated
+membranes improved the Allura red rejection from 8.29 $\pm$ 0.69% in the
+controls (sandwiched wood sheets without rGO) to 93.14 $\pm$ 1.31% in the 1 mL
+total rGO composites. The ratio of percentage permeance drop of the treatments
+over the controls ranged from 62.8 $\pm$ 4.3 to 85.4 $\pm$ 5.2% from the 0.4 to
+1 mL rGO composites respectively. The correlation coefficient (r) between the
+GO volume and rejection was 0.94 suggesting that the GO treatments provided
+some control over the transport of molecules through the membrane. The
+correlation coefficient between wood thickness, and Allura red rejection shows
+that the wood sheets did not influence the rejection. The permeance was weakly
+affected by the membrane thickness (r = -0.46). An 93% improvement in rejection
+performance of the composite membranes over the controls was observed. The
+overall data suggests that the wood-rGO composite has potential for water
+filtration applications.",2209.12983v1
+2022-10-11,First Principles Determination of the Potential-of-Zero-Charge in an Alumina-coated Aluminum/Water Interface Model for Corrosion Applications,"The surfaces of most metals immersed in aqueous electrolytes have a
+several-nanometer-thick oxide/hydroxide surface layer. This gives rise to the
+existence of both metal|oxide and oxide|liquid electrotlyte interfaces, and
+makes it challenging to correlate atomic length-scale structures with
+electrochemical properties such the potential-of-zero-charge (PZC). The PZC
+value has been shown to be correlated the pitting onset potential for
+corrosion. In this work, we conduct large-scale Density Functional Theory and
+ab initio molecular dynamics to calculate the PZC of a
+Al(111)|gamma-Al(2)O(3)(110)|water double-interface model within the context of
+aluminum corrosion. By partitioning the multiple interfaces involved into
+binary components with additive contributions to the overall work function and
+voltage, we predict the PZC to be -1.53 V vs. SHE for this model. We also
+calculate the orbital energy levels of defects like oxygen vacancies in the
+oxide, which are critical parameters in theories associated with pitting
+corrosion. We predict that the Fermi level at the PZC lies above the impurity
+defect levels of the oxygen vacancies, which are therefore uncharged at the
+PZC. From the PZC estimate, we predict the voltage needed to create oxygen
+vacancies with net positive charges within a flat-band approximation.",2210.05830v1
+2022-10-26,Liquid Metal Printed Ultrathin Oxides for Monolayer WS2 Top-Gate Transistors,"Two-dimensional (2D) semiconductors are promising channel materials for
+continued downscaling of complementary metal-oxide-semiconductor (CMOS) logic
+circuits. However, their full potential continues to be limited by a lack of
+scalable high-k dielectrics that can achieve atomically smooth interfaces,
+small equivalent oxide thicknesses (EOT), excellent gate control, and low
+leakage currents. Here, we report liquid metal printed ultrathin and scalable
+Ga2O3 dielectric for 2D electronics and electro-optical devices. We directly
+visualize the atomically smooth Ga2O3/WS2 interfaces enabled by the conformal
+nature of liquid metal printing. We demonstrate atomic layer deposition
+compatibility with high-k Ga2O3/HfO2 top-gate dielectric stacks on chemical
+vapour deposition grown monolayer WS2, achieving EOTs of ~1 nm and subthreshold
+swings down to 84.9 mV/dec. Gate leakage currents are well within requirements
+for ultra-scaled low-power logic circuits. Our results show that liquid metal
+printed oxides can bridge a crucial gap in scalable dielectric integration of
+2D materials for next-generation nano-electronics.",2210.14426v1
+2022-11-12,Evaluation of the hydrogen solubility and diffusivity in proton-conducting oxides by converting the PSL values of a tritium imaging plate,"Proton-conducting oxides have potential applications in hydrogen sensors,
+hydrogen pumps, and other electrochemical devices including the tritium
+purification and recovery systems of nuclear fusion reactors. Although the
+distribution of hydrogen (H) in such oxide materials is an important aspect,
+its precise measurement is difficult. In the present study, the hydrogen
+solubility and diffusivity behavior of BaZr0.9Y0.1O2.95 (BZY),
+BaZr0.955Y0.03Co0.015O2.97 (BZYC), and CaZr0.9In0.1O2.95 (CZI) were studied
+using tritiated heavy water vapor i.e., DTO (~2 kPa, tritium (T) = 0.1%) by
+converting the photostimulated luminescence (PSL) values of the imaging plate
+(IP). The samples were exposed to DTO vapor at 673 K for 2 h or at 873 K for 1
+h. The disc-shaped oxide specimens (diameter ~7.5 mm; thickness ~2.3 mm;
+theoretical density (TD) > 98 %) were prepared by conventional powder
+metallurgy. The IP images of the specimen surfaces of all the three materials
+T-exposed revealed that BZY showed the most uniform T distribution with the
+highest tritium activity. The cross-sectional T concentration profiles of the
+cut specimens showed that T diffused deeper into BZY and BZYC than into CZI.
+The hydrogen solubility and diffusivity in the CZI specimen were lower than
+that in the BZY and BZYC specimens. This suggested that barium zirconates were
+more favorable proton conductors than calcium zirconates.",2211.11531v1
+2023-02-15,Discovery of Atomic Clock-Like Spin Defects in Simple Oxides from First Principles,"Virtually noiseless due to the scarcity of spinful nuclei in the lattice,
+simple oxides hold promise as hosts of solid-state spin qubits. However, no
+suitable spin defect has yet been found in these systems. Using high-throughput
+first-principles calculations, we predict spin defects in calcium oxide with
+electronic properties remarkably similar to those of the NV center in diamond.
+These defects are charged complexes where a dopant atom -- Sb, Bi, or I --
+occupies the volume vacated by adjacent cation and anion vacancies. The
+predicted zero phonon line shows that the Bi complex emits in the
+telecommunication range, and the computed many-body energy levels suggest a
+viable optical cycle required for qubit initialization. Notably, the high-spin
+nucleus of each dopant strongly couples to the electron spin, leading to many
+controllable quantum levels and the emergence of atomic clock-like transitions
+that are well protected from environmental noise. Specifically, the Hanh-echo
+coherence time increases beyond seconds at the clock-like transition in the
+defect with \ch{^{209}Bi}. Our results pave the way to designing quantum states
+with long coherence times in simple oxides, making them attractive platforms
+for quantum technologies.",2302.07523v3
+2023-02-28,Correlating Chemical Reaction and Mass Transport in Hydrogen-based Direct Reduction of Iron Oxide,"Steelmaking contributes 8% to the total CO2 emissions globally, primarily due
+to coal-based iron ore reduction. Clean hydrogen-based ironmaking has variable
+performance because the dominant gas-solid reduction mechanism is set by the
+defects and pores inside the mm-nm sized oxide particles that change
+significantly as the reaction progresses. While these governing dynamics are
+essential to establish continuous flow of iron and its ores through reactors,
+the direct link between agglomeration and chemistry is still contested due to
+missing measurements. In this work, we directly measure the connection between
+chemistry and agglomeration in the smallest iron oxides relevant to magnetite
+ores. Using synthesized spherical 10-nm magnetite particles reacting in H2, we
+resolve the formation and consumption of w\""ustite (FeO) - the step most
+commonly attributed to agglomeration. Using X-ray scattering and microscopy, we
+resolve crystallographic anisotropy in the rate of the initial reaction, which
+becomes isotropic as the material sinters. Complementing with imaging, we
+demonstrate how the particles self-assemble, subsequently react and sinter into
+~100x oblong grains. Our insights into how morphologically uniform iron oxide
+particles react and agglomerate H2 reduction enable future size-dependent
+models to effectively describe the multiscale iron ore reduction.",2302.14215v2
+2023-03-09,Mechanisms of SiO oxidation: Implications for dust formation,"Reactions of SiO molecules have been postulated to initiate efficient
+formation of silicate dust particles in outflows around dying (AGB) stars. Both
+OH radicals and H$_2$O molecules can be present in these environments and their
+reactions with SiO and the smallest SiO cluster, Si$_2$O$_2$, affect the
+efficiency of eventual dust formation. Rate coefficients of gas-phase oxidation
+and clustering reactions of SiO, Si$_2$O$_2$ and Si$_2$O$_3$ have been
+calculated using master equation calculations based on density functional
+theory calculations. The calculations show that the reactions involving OH are
+fast. Reactions involving H$_2$O are not efficient routes to oxidation but may
+under the right conditions lead to hydroxylated species. The reaction of
+Si$_2$O$_2$ with H$_2$O, which has been suggested as efficient producing
+Si$_2$O$_3$, is therefore not as efficient as previously thought. If H$_2$O
+molecules dissociate to form OH radicals, oxidation of SiO and dust formation
+could be accelerated. Kinetics simulations of oxygen-rich circumstellar
+environments using our proposed reaction scheme suggest that under typical
+conditions only small amounts of SiO$_2$ and Si$_2$O$_2$ are formed and that
+most of the silicon remains as molecular SiO.",2303.05184v1
+2023-03-10,Hematite $α-Fe_{2}O_{3}(0001)$ in top and side view: resolving long-standing controversies about its surface structure,"Hematite ${\alpha}-Fe_{2}O_{3}(0001)$ is the most-investigated iron oxide
+model system in photo and electrocatalytic research. The rich chemistry of Fe
+and O allows for many bulk and surface transformations, but their control is
+challenging. This has led to controversies regarding the structure of the
+topmost layers. This comprehensive study combines surface methods (nc-AFM, STM,
+LEED, and XPS) complemented by structural and chemical analysis of the
+near-surface bulk (HRTEM and EELS). The results show that a compact 2D layer
+constitutes the topmost surface of ${\alpha}-Fe_{2}O_{3}(0001)$; it is locally
+corrugated due to the mismatch with the bulk. Assessing the influence of
+naturally-occurring impurities shows that these can force the formation of
+surface phases that are not stable on pure samples. Impurities can also cause
+the formation of ill-defined inclusions in the subsurface and modify the
+oxidation phase diagram of hematite. The results provide a significant step
+forward in determining the hematite surface structure that is crucial for
+accurately modeling catalytic reactions. Combining surface and cross-sectional
+imaging provided the full view that is essential for understanding the
+evolution of the near-surface region of oxide surfaces under oxidative
+conditions.",2303.06023v1
+2023-03-28,Optimizing compositional and atomic-level information of oxides in atom probe tomography,"Atom probe tomography (APT) is a 3D analysis technique that offers unique
+chemical accuracy and sensitivity with sub-nanometer spatial resolution.
+Recently, there is an increasing interest in the application of APT to complex
+oxides materials, giving new insight into the relation between local variations
+in chemical composition and emergent physical properties. However, in contrast
+to the field of metallurgy, where APT is routinely applied to study materials
+at the atomic level, complex oxides and their specific field evaporation
+mechanisms are much less explored. Here, we perform APT measurements on the
+hexagonal manganite ErMnO3 and systematically study the effect of different
+experimental parameters on the measured composition and atomic structure. We
+demonstrate that both the mass resolving power (MRP) and compositional accuracy
+can be improved by increasing the charge-state ratio (CSR) working at low laser
+energy (< 5 pJ). Furthermore, we observe a substantial preferential retention
+of Er atoms, which is suppressed at higher CSRs. We explain our findings based
+on fundamental field evaporation concepts, expanding the knowledge about the
+impact of key experimental parameters and the field evaporation process in
+complex oxides in general.",2303.16233v1
+2023-04-17,Mechanical behavior of ion-irradiated ODS RAF steels strengthened with different types of refractory oxides,"In the present work, authors focused on verifying structural and mechanical
+properties of Oxide Dispersed Strengthening (ODS) steels strengthened by three
+different types of refractory oxides submitted to ion-irradiation. Three
+materials strengthened with Y2O3 or Al2O3 or ZrO2 were produced by mechanical
+alloying and Spark Plasma Sintering technique. Specimens have been submitted to
+high energy Ar-ion irradiation at room temperature with three fluences. This
+procedure allowed to generate strongly damaged zone with a thickness of 230nm.
+SEM/EBSD and TEM observations, GIXRD analysis, and nanoindentation tests have
+been included in examination of modified layers. Investigation revealed
+alteration of structural and mechanical features as a result of Ar-irradiation.
+Obtained results showed a strong correlation between the strengthening oxide
+and materials' behavior under radiation damage. It has been proved that below
+1x1015ions/cm2 mechanical properties in the modified layer of all materials are
+very similar. Reported behavior may be related to the efficient annealing of
+the radiation defect process. Above this limit, significant differences between
+the materials are visible. It is believed that described phenomenon is directly
+related to the presence of the structural features and their capacity to act as
+defect sinks. Consequently, type of dominant mechanisms occurring in modified
+layer is proposed.",2304.08266v1
+2023-04-30,Factors determining surface oxygen vacancy formation energy in ternary spinel structure oxides with zinc,"Spinel oxides are an important class of materials for heterogeneous catalysis
+including photocatalysis and electrocatalysis. The surface O vacancy formation
+energy (EOvac) is a critical quantity on catalyst performance because the
+surface of metal oxide catalysts often acts as reaction sites, for example, in
+the Mars-van Krevelen mechanism. However, experimental evaluation of EOvac is
+very challenging. We obtained the EOvac for (100), (110), and (111) surfaces of
+normal zinc-based spinel oxides ZnAl2O4, ZnGa2O4, ZnIn2O4, ZnV2O4, ZnCr2O4,
+ZnMn2O4, ZnFe2O4, and ZnCo2O4. The most stable surface is (100) for all
+compounds. The smallest EOvac for a surface is the largest in the (100) surface
+except for ZnCo2O4. For (100) and (110) surfaces, there is a good correlation,
+over all spinels, between the smallest EOvac for the surface and bulk formation
+energy, while the ionization potential correlates well in (111) surfaces.
+Machine learning over EOvac of all surface sites in all orientations and all
+compounds to find the important factors, or descriptors, that decide the EOvac
+revealed that bulk and surface-dependent descriptors are the most important,
+namely the bulk formation energy, a Boolean descriptor on whether the surface
+is (111), and the ionization potential, followed by geometrical descriptors
+that are different in each O site.",2305.00395v1
+2023-05-11,Reactive pulsed direct current magnetron sputtering deposition of semiconducting yttrium oxide thin film in ultralow oxygen atmosphere: A spectroscopic and structural investigation of growth dynamics,"An experimental investigation was conducted to explore spectroscopic and
+structural characterization of semiconducting yttrium oxide thin film deposited
+at 623 K (+/- 5K) utilizing reactive pulsed direct current magnetron
+sputtering. Based on the results obtained from both x-ray diffraction and
+transmission electron microscope measurements, yttrium monoxide is very likely
+formed in the transition region between {\beta}-Y2O3 and {\alpha}-Y2O3, and
+accompanied by the crystalline Y2O3. Resulting from either the low energy
+separation between 4d and 5s orbitals and/or different spin states of the
+corresponding orbitals' sublevels, the stability of monoxide is most presumably
+self-limited by the size of the crystal in thermodynamic terms. This behavior
+develops a distortion in the structure of the crystal compared to the metal
+oxide cubic structure and it also effectuates the arrangement in
+nanocrystalline/amorphous phase. In addition to this, spectroscopic
+ellipsometry denotes that the semiconducting yttrium oxide has the dominant,
+mostly amorphous, formation character over crystalline Y2O3. Our purpose, by
+means of the current findings, is to advance the understanding of formation
+kinetics/conditions of yttrium with an unusual valency (2+).",2305.06757v1
+2023-05-15,Superconducting-insulating quantum phase transition associated with valence change in compressed perovskite bismuth-oxides,"Searching for a universal trend by the same tuning method in different
+high-temperature superconductors with a similar crystal structure is a common
+strategy to find clues for a better understanding of the superconducting
+mechanism in a unified way. It is known that the hole-doped bismuth-oxide
+Ba1-xKxBiO3 possesses a similar perovskite structure to that of the hole-doped
+copper-oxide (cuprate) superconductors but also holds a comparatively high
+superconducting transition temperature. In this study, we report the first
+observation of the pressure-induced quantum phase transition (QPT) from
+superconducting to insulating states in a series of Ba1-xKxBiO3 single-crystal
+samples. A similar QPT has also been observed recently in the compressed
+cuprate superconductors1. Significantly, we found that the QPT observed in
+Ba1-xKxBiO3 is intriguingly associated with the valence change of the Bi ions
+in the material. These results lead us to propose that the pressure-induced
+valence change from Bi3+ to Bi5+ destroys the hole-doping effect on stabilizing
+the conductivity and corresponding superconductivity. By comparing the
+high-pressure behaviors observed in these two kinds of oxides, we identified
+another prominent feature shared by them - the more the hole-doping
+concentration, the higher the critical pressure required for driving the QPT.",2305.08406v1
+2023-07-07,Robust atmospherically stable hybrid SrVO3/Graphene//SrTiO3 template for fast and facile large-area transfer of complex oxides onto Si,"Heterogenous integration of complex epitaxial oxides onto Si and other target
+substrates is recently gaining traction. One of the popular methods involves
+growing a water-soluble and highly reactive sacrificial buffer layer, such as
+Sr3Al2O6 (SAO) at the interface, and a functional oxide on top of this. To
+improve the versatility of layer transfer techniques, it is desired to utilize
+stable (less reactive) sacrificial layers, without compromising on the transfer
+rates. In this study, we utilized a combination of chemical vapor deposited
+(CVD) graphene as a 2D material at the interface and pulsed laser deposited
+(PLD) water-soluble SrVO3 (SVO) as a sacrificial buffer layer. We show that the
+graphene layer enhances the dissolution rate of SVO over ten times without
+compromising its atmospheric stability. We demonstrate the versatility of our
+hybrid template by growing ferroelectric BaTiO3 (BTO) via PLD and Pb(Zr, Ti)O3
+(PZT) via Chemical Solution Deposition (CSD) technique and transferring them
+onto the target substrates and establishing their ferroelectric properties. Our
+hybrid templates allow for the realization of the potential of complex oxides
+in a plethora of device applications for MEMS, electro-optics, and flexible
+electronics.",2307.03342v1
+2023-07-27,$ \mathrm{Sr}_{4}\mathrm{Al}_{2}\mathrm{O}_{7}$: A New Sacrificial Layer with High Water Dissolution Rate for the Synthesis of Freestanding Oxide Membranes,"Freestanding perovskite oxide membranes have drawn great attention recently
+since they offer exceptional structural tunability and stacking ability,
+providing new opportunities in fundamental research and potential device
+applications in silicon-based semiconductor technology. Among different types
+of sacrificial layers, the $ \mathrm{(Ca, Sr,
+Ba)}_{3}\mathrm{Al}_{2}\mathrm{O}_{6}$ compounds are most widely used since
+they can be dissolved in water and prepare high-quality perovskite oxide
+membranes with clean and sharp surfaces and interfaces. However, the typical
+transfer process takes a long time (up to hours) in obtaining millimeter-size
+freestanding membranes, let alone realize wafer-scale samples with high yield.
+Here, we introduce a new member of the $
+\mathrm{SrO-}\mathrm{Al}_{2}\mathrm{O}_{3}$ family,$
+\mathrm{Sr}_{4}\mathrm{Al}_{2}\mathrm{O}_{7},$, and demonstrate its high
+dissolution rate, about 10 times higher than that of $
+\mathrm{Sr}_{3}\mathrm{Al}_{2}\mathrm{O}_{6}$. The high-dissolution-rate of $
+\mathrm{Sr}_{4}\mathrm{Al}_{2}\mathrm{O}_{7}$ is most likely related to the
+more discrete Al-O networks and higher concentration of water-soluble Sr-O
+species in this compound. Our work significantly facilitates the preparation of
+freestanding membranes and sheds light on the integration of multifunctional
+perovskite oxides in practical electronic devices.",2307.14584v1
+2023-08-01,Autonomous data extraction from peer reviewed literature for training machine learning models of oxidation potentials,"We present an automated data-collection pipeline involving a convolutional
+neural network and a large language model to extract user-specified tabular
+data from peer-reviewed literature. The pipeline is applied to 74 reports
+published between 1957 and 2014 with experimentally-measured oxidation
+potentials for 592 organic molecules (-0.75 to 3.58 V). After data curation
+(solvents, reference electrodes, and missed data points), we trained multiple
+supervised machine learning models reaching prediction errors similar to
+experimental uncertainty ($\sim$0.2 V). For experimental measurements of
+identical molecules reported in multiple studies, we identified the most likely
+value based on out-of-sample machine learning predictions. Using the trained
+machine learning models, we then estimated oxidation potentials of $\sim$132k
+small organic molecules from the QM9 data set, with predicted values spanning
+0.21 to 3.46 V. Analysis of the QM9 predictions in terms of plausible
+descriptor-property trends suggests that aliphaticity increases the oxidation
+potential of an organic molecule on average from $\sim$1.5 V to $\sim$2 V,
+while an increase in number of heavy atoms lowers it systematically. The
+pipeline introduced offers significant reductions in human labor otherwise
+required for conventional manual data collection of experimental results, and
+exemplifies how to accelerate scientific research through automation.",2308.00389v1
+2023-08-06,Mechanically exfoliated low-layered [Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$]: A single-crystalline p-type transparent conducting oxide,"Transparent conducting oxides (TCOs) are essential components of
+optoelectronic devices and various materials have been explored for highly
+efficient TCOs having a combination of high transmittance and low sheet
+resistance. Here, we focus on a misfit thermoelectric oxide
+[Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$] and fabricate the transparent low-layered
+crystals by a mechanical tape-peeling method using the single-crystalline
+samples. From the transmittance measurement, we find that the thickness of
+low-layered samples is several orders of hundred nanometers, which is
+comparable with the estimation from the scanning electron microscopy images.
+Compared to the previous results on the polycrystalline and $c$-axis oriented
+transparent films, the electrical resistivity is reduced owing to the
+single-crystalline nature. The figure of merit for the transparent conducting
+materials in the present low-layered samples is then evaluated to be higher
+than the values in the previous reports. The present results on the low-layered
+single-crystalline [Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$] may offer a unique class
+of multi-functional transparent thermoelectric oxides.",2308.03221v1
+2023-08-23,Atomic scale understanding of initial Cu-Ni oxidation from machine-learning accelerated first-principles simulations and in situ TEM experiments,"The development of accurate methods for determining how alloy surfaces
+spontaneously restructure under reactive and corrosive environments is a key,
+long-standing, grand challenge in materials science. Current oxidation models,
+such as Cabrera-Mott, are based on macroscopic empirical knowledge that lacks
+fundamental insight at the atomic level. Using machine learning-accelerated
+density functional theory with in situ environmental transmission electron
+microscopy (ETEM), we examine the interplay between surface reconstructions and
+preferential segregation tendencies of CuNi(100) surfaces under oxidation
+conditions. Our modeling approach based on molecular dynamics and grand
+canonical Monte Carlo simulations shows that oxygen-induced Ni segregation in
+CuNi alloy favors Cu(100)-O c(2x2) reconstruction and destabilizes the
+Cu(100)-O missing row reconstruction. The underpinnings of these stabilization
+tendencies are rationalized based on the similar atomic coordination and bond
+lengths in NiO rock salt and Cu(100)-O c(2x2) structures. In situ ETEM
+experiments show Ni segregation followed by NiO nucleation and growth in
+regions without MRR, with secondary nucleation and growth of Cu2O in MRR
+regions. This further corroborates the simulated surface oxidation and
+segregation modelling outcomes. Our findings are general and are expected to
+extend to other alloy systems.",2308.11867v1
+2023-09-21,Shedding Light on the Ageing of Extra Virgin Olive Oil: Probing the Impact of Temperature with Fluorescence Spectroscopy and Machine Learning Techniques,"This work systematically investigates the oxidation of extra virgin olive oil
+(EVOO) under accelerated storage conditions with UV absorption and total
+fluorescence spectroscopy. With the large amount of data collected, it proposes
+a method to monitor the oil's quality based on machine learning applied to
+highly-aggregated data. EVOO is a high-quality vegetable oil that has earned
+worldwide reputation for its numerous health benefits and excellent taste.
+Despite its outstanding quality, EVOO degrades over time owing to oxidation,
+which can affect both its health qualities and flavour. Therefore, it is highly
+relevant to quantify the effects of oxidation on EVOO and develop methods to
+assess it that can be easily implemented under field conditions, rather than in
+specialized laboratories. The following study demonstrates that fluorescence
+spectroscopy has the capability to monitor the effect of oxidation and assess
+the quality of EVOO, even when the data are highly aggregated. It shows that
+complex laboratory equipment is not necessary to exploit fluorescence
+spectroscopy using the proposed method and that cost-effective solutions, which
+can be used in-field by non-scientists, could provide an easily-accessible
+assessment of the quality of EVOO.",2309.12377v1
+2023-09-27,Optical tuning of the diamond Fermi level measured by correlated scanning probe microscopy and quantum defect spectroscopy,"Quantum technologies based on quantum point defects in crystals require
+control over the defect charge state. Here we tune the charge state of shallow
+nitrogen-vacancy and silicon-vacancy centers by locally oxidizing a
+hydrogenated surface with moderate optical excitation and simultaneous spectral
+monitoring. The loss of conductivity and change in work function due to
+oxidation are measured in atmosphere using conductive atomic force microscopy
+(C-AFM) and Kelvin probe force microscopy (KPFM). We correlate these scanning
+probe measurements with optical spectroscopy of the nitrogen-vacancy and
+silicon-vacancy centers created via implantation and annealing 15-25 nm beneath
+the diamond surface. The observed charge state of the defects as a function of
+optical exposure demonstrates that laser oxidation provides a way to precisely
+tune the Fermi level over a range of at least 2.00 eV. We also observe a
+significantly larger oxidation rate for implanted surfaces compared to
+unimplanted surfaces under ambient conditions. Combined with knowledge of the
+electron affinity of a surface, these results suggest KPFM is a powerful,
+high-spatial resolution technique to advance surface Fermi level engineering
+for charge stabilization of quantum defects.",2309.15969v1
+2023-10-11,Thickness-dependent Characteristics and Oxidation of Cadmium,"In this study, the structural, electronic and vibrational properties of
+thinnest possible Cadmium crystal are investigated by performing
+first-principle calculations. Total energy optimization and dynamic stability
+calculations reveal that the thinnest possible crystal structure is a
+double-layered structure consisting of alternating layers formed by trigonal
+arrangements of Cd atoms. Excessive softening of optical phonons occurs as a
+result of structural relaxation when going from a bulk to a single layer (SL)
+structure. It is also shown that thinnest structure obtained from bulk Cd
+crystals maintains its metallic feature despite the dimensional crossover. In
+addition, it is predicted through calculations that the SL Cd crystal strongly
+interacts with oxygen and that the oxidized regions even undergo chemical
+transformation to form the CdO crystal. In the double-layer CdO crystal
+resulting from the oxidation of individual Cd layers, the layers are connected
+to each other with strong covalent bonds, and this structure is a semiconductor
+with a band gap of 2.10 eV. While the robust metallic structure of the thinnest
+possible Cd crystal provides flexibility in terms of its use in nanoscale
+applications, on the other hand, the fact that its electronic properties can be
+changed by oxidation is important for optoelectronic device applications.",2310.07909v2
+2023-11-08,Direct electrochemical reduction of graphene oxide thin film for aptamer-based selective and highly sensitive detection of Matrix metalloproteinase 2,"Simple and low-cost biosensing solutions are suitable for point-of-care
+applications aiming to overcome the gap between scientific concepts and
+technological production. To compete with sensitivity and selectivity of golden
+standards, such as liquid chromatography, the functionalization of biosensors
+is continuously optimized to enhance the signal and improve their performance,
+often leading to complex chemical assay development. In this research, the
+efforts are made on optimizing the methodology for electrochemical reduction of
+graphene oxide to produce thin film-modified gold electrodes. Under the
+employed specific conditions, 20 cycles of cyclic voltammetry (CV) are shown to
+be optimal for superior electrical activation of graphene oxide into
+electrochemically reduced graphene oxide (ERGO). This platform is further used
+to develop a matrix metalloproteinase 2 (MMP-2) biosensor, where specific
+anti-MMP2 aptamers are utilized as a biorecognition element. MMP-2 is a protein
+which is typically overexpressed in tumor tissues, with important roles in
+tumor invasion, metastasis as well as in tumor angiogenesis. Based on
+impedimetric measurements, we were able to detect as low as 3.32 pg/mL of MMP-2
+in PBS with a dynamic range of 10 pg/mL - 10 ng/mL. Besides high specificity,
+ERGO-based aptasensor showed a potential of reuse due to demonstrated
+successful signal restoration after experimental detection of MMP-2.",2311.04674v2
+2023-11-27,Tailoring the Opto-Electronic Properties of Oxide-Metal-Oxide Transparent Electrode Using Cu Seed Layer,"The oxide-metal-oxide architecture is a promising approach for the
+development of the high-performance indium-free transparent electrode (TE),
+which is a key component of various optoelectronic applications such as solar
+cells, organic LEDs, and touchscreen panels. Here in this work, we have shown
+high-performance TE consisting of TiO2/Ag/TiO2 (TAT), with the incorporation of
+a copper seed layer. The seed layer increases the wettability and improves the
+adhesion of deposited Ag film on the bottom TiO2 layer. Before the experimental
+realization, optical modeling is performed by using MATLAB code based on the
+transfer matrix method. The optimum thickness obtained from the simulation is
+30 nm for both undercoat and overcoat TiO2 with the average transmittance in
+the visible region >85% with the Ag thickness of 9nm. With inputs from the
+optical modeling, TEs were experimentally realized with and without the Cu seed
+layer. It has been found that the TE with an additional sputtered Cu (1 nm)
+seed layer is essential for the smooth growth of silver film and shows better
+electro-optical performance (sheet resistance < 10 and average transmittance in
+the visible spectral range > 80%) than TAT-TE without any seed layer. The
+electro-optical and morphological properties of the TiO2/Cu/Ag/TiO2 structure
+make it suitable for optoelectronic applications.",2311.15535v2
+2023-11-28,Metal-to-insulator transition in oxide semimetals by anion doping,"Oxide semimetals exhibiting both nontrivial topological characteristics stand
+as exemplary parent compounds and multiple degrees of freedom, offering great
+promise for the realization of novel electronic states. In this study, we
+present compelling evidence of profound structural and transport phase shifts
+in a recently uncovered oxide semimetal, SrNbO3, achieved through effective
+in-situ anion doping. Notably, a remarkable increase in resistivity of more
+than three orders of magnitude at room temperature is observed upon
+nitrogen-doping. The extent of electronic modulation in SrNbO3 is strongly
+correlated with the misfit strain, underscoring its phase instability to both
+chemical doping and crystallographic symmetry variations. Using
+first-principles calculations, we discern that elevating the level of nitrogen
+doping induces an upward shift in the conductive bands of SrNbO3-dNd.
+Consequently, a transition from a metallic state to an insulating state becomes
+apparent as the nitrogen concentration reaches a threshold of 1/3. This
+investigation sheds light on the potential of anion engineering in oxide
+semimetals, offering pathways for manipulating their physical properties. These
+insights hold promise for future applications that harness these materials for
+tailored functionalities.",2311.16405v1
+2023-12-11,Investigating intrinsic silicon oxide and a lightly doped p-type layer for evolution of tail states and estimating its impact as a passivation layer in a HIT type device,"Hydrogenated amorphous silicon is well known for its various alloys and wide
+ranging opto-electronic properties. Hydrogenated silicon sub-oxide (aSiO:H) is
+one of them. The effect of boron doping on optoelectronic properties of the
+aSiO:H have been investigated with intrinsic and delta-doped materials. The
+Urbach energy of the tail and midgap defect states of the intrinsic and lightly
+doped(0.01% gas phase doping) materials were found to be 103, 151 meV and
+8.19x1016 , 5.47x1017 cm-3 respectively. As a result of the 0.01% doping a
+reduction in optical gap was observed from 1.99 to 1.967 eV along with a shift
+in Fermi level by 0.258eV, indicating an efficient boron doping of the
+intrinsic silicon oxide material. The lightly doped p-type layer was used to
+simulate device characteristics in amorphous silicon (aSi:H) and HIT-type solar
+cell. In the aSi:H device the power conversion efficiency (PCE) was moderate
+while in a HIT-type device the PCE was 26.4%. It indicated that a good quality
+silicon oxide layer can be an attractive passivation layer for a HIT type
+device. It further indicated that defect density of the passivation layer can
+have a significant impact on performance of a HIT type device. The primary
+difference of the two passivation layers (intrinsic and delta-doped) are the
+difference in mid-gap and tail states. Passivation layer with a higher mid-gap
+state leads to poorer device performance. Therefore, it highlights the
+importance of using a less defective passivation layer to improve device
+performance.",2312.06111v1
+2024-01-07,Dynamic Multi Color Switching using Ultrathin Vanadium Oxide on Aluminium based Asymmetric Fabry-Perot Resonant Structure,"Vanadium dioxide ($VO_{2}$) exhibits strong infrared optical switching due to
+its insulator-metal phase-transition property. However, in the visible
+wavelengths, it's intrinsic optical switching is quite low. Current research
+explores solutions like multilayering, intricate structural patterning, high
+thermal budget processes and costly metals for improved color switching.
+Nonetheless, the color gamut coverage with these methodologies remains notably
+limited. This work overcomes these limitations and demonstrates dynamic
+multi-colour switching covering a large color gamut using a simple,
+unpatterned, ultrathin ($\sim$ $\frac{\lambda}{14}$, where wavelength $\lambda$
+is taken as 575 nm at the center of visible spectrum) asymmetric
+Fabry-P\'{e}rot structure of $VO_{2}$ on Aluminium (Al). We use the transfer
+matrix method to design the $VO_{2}/Aluminium\,(Al)/Sapphire$ structure for
+maximum visible reflectance switching. $VO_{2}$ films are synthesized using a
+simple, low thermal budget atmospheric oxidation of Vanadium (V). With varying
+oxidation durations, different colors of the oxidized samples are observed.
+Consistent and reversible color-switching is observed visibly and in
+reflectance measurements with the change in temperature from low (RT $\sim$
+30$^{\circ}$C) to high (HT $\sim$ 100$^{\circ}$C) or vice versa due to the
+phase transition property of the $VO_{2}$ layer in the structure. Compared to
+the existing studies, this work shows a significant change in chromaticities
+and covers a large color gamut when plotted on the CIE chromaticity diagram.
+This work has potential applications in the fields of display, thermochromic
+structures, and visible camouflage.",2401.03543v1
+2024-01-14,Etching of elemental layers in oxide molecular beam epitaxy by O2-assisted formation and evaporation of their volatile suboxide: The examples of Ga and Ge,"The delivery of an elemental cation flux to the substrate surface in the
+oxide molecular beam epitaxy (MBE) chamber has been utilized not only for the
+epitaxial growth of oxide thin films in the presence of oxygen but also in the
+absence of oxygen for the growth temperature calibration (by determining the
+adsorption temperature of the elements) and in-situ etching of oxide layers (e.
+g., Ga2O3 etched by Ga). These elemental fluxes may, however, leave unwanted
+cation adsorbates or droplets on the surface, which traditionally require
+removal by in-situ superheating or ex-situ wet-chemical etching with
+potentially surface-degrading effects. This study demonstrates a universal
+in-situ approach to remove the residual cation elements from the surface via
+conversion into a volatile suboxide by a molecular O2-flux in an MBE system
+followed by suboxide evaporation at temperatures significantly below the
+elemental evaporation temperature. We experimentally investigate the in-situ
+etching of Ga and Ge cation layers and their etching efficiency using in-situ
+line-of-sight quadrupole mass spectrometry (QMS) and reflection high-energy
+electron diffraction (RHEED). The application of this process is demonstrated
+by the in-situ removal of residual Ga droplets from a SiO2 mask after
+structuring a Ga2O3 layer by in-situ Ga-etching. This approach can be generally
+applied in MBE and MOCVD to remove residual elements with vapor pressure lower
+than that of their suboxides, such as B, In, La, Si, Sn, Sb, Mo, Nb, Ru, Ta, V,
+and W.",2401.07374v1
+2024-01-15,Alternating Bias Assisted Annealing of Amorphous Oxide Tunnel Junctions,"We demonstrate a transformational technique for controllably tuning the
+electrical properties of fabricated thermally oxidized amorphous aluminum-oxide
+tunnel junctions. Using conventional test equipment to apply an alternating
+bias to a heated tunnel barrier, giant increases in the room temperature
+resistance, greater than 70%, can be achieved. The rate of resistance change is
+shown to be strongly temperature-dependent, and is independent of junction size
+in the sub-micron regime. In order to measure their tunneling properties at mK
+temperatures, we characterized transmon qubit junctions treated with this
+alternating-bias assisted annealing (ABAA) technique. The measured frequencies
+follow the Ambegaokar-Baratoff relation between the shifted resistance and
+critical current. Further, these studies show a reduction of
+junction-contributed loss on the order of $\approx 2 \times10^{-6}$, along with
+a significant reduction in resonant- and off-resonant-two level system defects
+when compared to untreated samples. Imaging with high-resolution TEM shows that
+the barrier is still predominantly amorphous with a more uniform distribution
+of aluminum coordination across the barrier relative to untreated junctions.
+This new approach is expected to be widely applicable to a broad range of
+devices that rely on amorphous aluminum oxide, as well as the many other
+metal-insulator-metal structures used in modern electronics.",2401.07415v2
+2024-01-22,Two New Members of the Covalent Organic Frameworks Family: Crystalline 2D-Oxocarbon and 3D-Borocarbon Structures,"While graphene oxide (GO) is representative of a disordered phase of
+oxocarbons with lackluster electronic properties, the coexistence of ordered,
+stoichiometric solid-state carbon oxides with graphene brings renewed momentum
+to the exploration of two-dimensional crystalline oxocarbons. This enduring
+subject, spanning decades, has recently witnessed significant advancements. In
+this context, our study delves into a novel material class, COF-66, notable for
+its meticulously ordered two-dimensional crystalline structure and intrinsic
+porosity. Employing a global optimization algorithm alongside
+density-functional calculations, our investigation highlights a standout member
+within the COF-66 family exceptional quasi-flat oxocarbon (C6O6)exhibiting an
+unconventional oxygen-decorated pore configuration. This pioneering study
+introduces C6O6 as an innovative entrant into the crystalline carbon oxide
+arena, augmenting the established understanding alongside the well-recognized
+graphene oxide and two graphene monoxide, i.e. {\alpha}-GMO and \b{eta}-GMO.
+Expanding the exploration, the COF-66 series encompasses 2D-porous carbon
+nitride (C6N6) and the recently synthesized 2D-porous boroxine (B6O6), adhering
+to a generalized stoichiometry of X6Y6, where X = B, C, and Y = B, N, O, with X
+6= Y. Remarkably, the entire COF-66 ensemble adopts a 2D-crystalline framework,
+with the exception of C6B6, which assumes a distinct 3D-crystalline
+arrangement. Employing the PBE (HSE06) level of theory, our electronic
+structure calculations yield band gap values of 0.01 (0.05) eV, 3.68 (5.29) eV,
+0.00 (0.23) eV, and 1.53 (3.09) eV for B6N6, B6O6, C6B6, and C6N6,
+respectively, reinforcing and aligning with prior investigations.",2401.11843v1
+2024-03-05,Highly Reproducible and CMOS-compatible VO2-based Oscillators for Brain-inspired Computing,"With remarkable electrical and optical switching properties induced at low
+power and near room temperature (68C), vanadium dioxide (VO2) has sparked
+rising interest in unconventional computing among the phase-change materials
+research community. The scalability and the potential to compute beyond the von
+Neumann model make VO2 especially appealing for implementation in oscillating
+neural networks for artificial intelligence (AI) applications, to solve
+constraint satisfaction problems, and for pattern recognition. Its integration
+into large networks of oscillators on a Silicon platform still poses challenges
+associated with the stabilization in the correct oxidation state and the
+ability to fabricate a structure with predictable electrical behavior showing
+very low variability. In this work, the role played by the different annealing
+parameters applied by three methods (slow thermal annealing, flash annealing,
+and rapid thermal annealing), following the vanadium oxide atomic layer
+deposition (ALD), on the formation of VO2 grains is studied and an optimal
+substrate stack configuration that minimizes variability between devices is
+proposed. Material and electrical characterizations are performed on the
+different films and a step-by-step recipe to build reproducible VO2-based
+oscillators is presented, which is argued to be made possible thanks to the
+introduction of a hafnium oxide (HfO2) layer between the silicon substrate and
+the vanadium oxide layer. Up to seven nearly identical VO2-based devices are
+contacted simultaneously to create a network of oscillators, paving the way for
+large-scale implementation of VO2 oscillating neural networks.",2403.02822v1
+2024-03-14,Multi-droplet combustion in the presence of homogeneous and heterogeneous atomizations,"The effects of heterogeneous and homogeneous atomizations on combustion
+dynamics and flame spread rates of multi-droplets are experimentally
+investigated. The utilized fuel is biodiesel, which is doped with graphene
+oxide and blended with ethanol. Stable fuel suspensions are prepared. Either
+one droplet is positioned at the intersection of two thin fibers or an array of
+three droplets are positioned along a horizontal line and at the intersections
+of fibers. Simultaneous and time-resolved flame chemiluminescence and
+shadowgraphy techniques are utilized for imaging the flame and droplets,
+respectively. It is observed that, for a single droplet combustion of
+biodiesel, relatively low frequency (about 10 Hz) dynamics appear in the second
+half of the droplet life-time, which is due to heterogeneous atomizations.
+Blending with ethanol leads to homogeneous atomizations with dynamics featuring
+frequencies smaller than 50 Hz and at the beginning of the droplet lifetime. It
+is reported that the homogeneous atomizations lead to at least three times
+larger root-mean-square oscillations of the flame chemiluminescence compared to
+that for heterogeneous atomizations. For all tested multi-droplet
+configurations, independent of the graphene oxide doping concentration and
+blending with ethanol, the most dominant frequency of flame chemiluminescence
+oscillations is about 10-15 Hz. It is observed that the heterogeneous
+atomizations lead to a flame spread rate of about 6-8 mm2/s, with largest
+values reported for doping with moderate concentration of graphene oxide.
+Compared to that for heterogeneous atomizations, the flame spread rate for
+homogeneous atomizations are significantly larger 10-40 mm2/s, are not
+sensitive to graphene oxide doping concentration, and feature a positive
+relation with the root-mean-square of the flame chemiluminescence oscillations.",2403.09823v1
+2024-03-25,Direct activation of PMS by highly dispersed amorphous CoOx clusters in anatase TiO2 nanosheets for efficient oxidation of biomass-derived alcohols,"Developing a green and cost-effective catalytic system for the selective
+oxidation of biomass-derived alcohols is vital for the sustainable synthesis of
+fine chemicals. Herein, highly dispersed subnanometric amorphous CoOx clusters
+in anatase TiO2 nanosheets (Co-TiO2) fabricated by green solvent CO2 assisted
+approach could directly activate peroxymonosulfate (PMS) for the highly
+selective oxidation of various biomass-derived alcohols. Advanced
+characterizations (e.g., EXAFS, EPR, AC HAADF-STEM) reveal that a strong
+interaction of CoOx clusters and the anatase TiO2 support exist in Co-TiO2 and
+Co atom in Co-TiO2 is mainly consisted of Co2+ and Co3+. The Co-TiO2 catalyst
+offers superior catalytic performance in the conversion of six types of
+alcohols (e.g., benzyl alcohol (BAL), 5-hydroxymethylfurfural (HMF)) with high
+selectivity to produce corresponding aldehydes. Highly dispersed CoOx clusters
+and the interaction between CoOx clusters and TiO2 support contribute to the
+superior performance. Mechanism studies show that SO4 radicals play the
+dominant role in the selective oxidation of model reactant BAL and 1O2
+participates in the non-radical pathway. DFT calculations are well matched with
+experiment and decipher that the strong interaction between CoOx clusters and
+TiO2 support promotes the formation of SO4 and SO5.",2403.16733v1
+2006-12-04,Discovery of Fundamental Mass Ratio Relationships of Whole-Rock Chondritic Major Elements: Implications on Ordinary Chondrite Formation and on Planet Mercury's Composition,"The high occurrence on Earth of ordinary chondrite meteorites and the making
+of models based upon arbitrary assumptions has led to some confusion about the
+origin of ordinary chondrites. Major element fractionation among chondrites has
+been discussed for decades as ratios relative to Si or Mg. Expressing ratios
+relative to Fe leads to a new relationship admitting the possibility that
+ordinary chondrite meteorites are derived from two components: one is a
+relatively undifferentiated, primitive component, oxidized like the CI or C1
+chondrites; the other is a somewhat differentiated, planetary component, with
+oxidation state like the reduced enstatite chondrites. Such a picture would
+seem to explain for the ordinary chondrites, their major element compositions,
+their intermediate states of oxidation, and their ubiquitous defiencies of
+refractory siderophile elements. I suggest that the planetary component of
+ordinary chondrite formation consists of planet Mercury's missing complement of
+elements, presumably separated from protoplanetary Mercury during its
+formation.",0612062v1
+1996-05-07,Electronic Hamiltonian for Transition Metal Oxide Compounds,"An effective electronic Hamiltonian for transition metal oxide compounds is
+presented. For Mn-oxides, the Hamiltonian contains spin-2 ``spins'' and
+spin-3/2 ``holes'' as degrees of freedom. The model is constructed from the
+Kondo-lattice Hamiltonian for mobile $e_g$ electrons and localized $t_{2g}$
+spins, in the limit of a large Hund's coupling. The effective electron bond
+hopping amplitude fluctuates in sign as the total spin of the bond changes. In
+the large spin limit, the hopping amplitude for electrons aligned with the core
+ions is complex and a Berry phase is accumulated when these electrons move in
+loops. The new model is compared with the standard double exchange Hamiltonian.
+Both have ferromagnetic ground states at finite hole density and low
+temperatures, but their critical temperatures could be substantially different
+due to the frustration effects induced by the Berry phase.",9605041v1
+1996-09-12,Ferromagnetism in Electronic Models for Manganites,"Ground state properties of the Kondo model for manganese oxides in one
+dimension are studied using numerical techniques. The large Hund coupling
+($J_{H}$) limit is specially analyzed. A robust region of fully saturated
+ferromagnetism (FM) is identified at all densities. For open boundary
+conditions it is shown exactly that the ground state is FM at $J_{H} = \infty$.
+Hole-spin phase separation competing with FM was also observed when a large
+exchange $J$ between the $Mn^{3+}$ ions is used. As the spin of the transition
+metal ion grows, the hole mobility decreases providing a tentative explanation
+for the differences between Cu-oxides and Mn-oxides.",9609111v2
+1997-09-30,Electron Correlation and Jahn-Teller Interaction in Manganese Oxides,"The interplay between the electron repulsion $U$ and the Jahn-Teller
+electron-phonon interation $E_{LR}$ is studied with a large $d$ model for the
+ferromagnetic state of the manganese oxides. These two interactions collaborate
+to induce the local isospin (orbital) moments and reduce the bandwidth $B$.
+Especially the retardation effect of the Jahn-Teller phonon with the frequency
+$\Omega$ is effective to reduce $B$, but the strong $\Omega$-dependence occurs
+even when the Coulombic interaction is dominating ($ U >> E_{LR}$) as long as
+$E_{LR} > \Omega$. The phonon spectrum consists of two components, i.e., the
+temperature independent sharp peak at $\omega = {\tilde \Omega} = \Omega [(U +4
+E_{LR})/U]^{1/2}$ and that corresponding to the Kondo peak. These results
+compared with the experiments suggest that $\Omega <E_{LR} <U$ in the metallic
+manganese oxides.",9709335v1
+1998-05-27,Nanolithography by non-contact AFM induced local oxidation : Fabrication of tunneling barriers suitable for single electron devices,"We study local oxidation induced by dynamic atomic force microscopy (AFM),
+commonly called TappingMode AFM. This minimizes the field induced forces, which
+cause the tip to blunt, and enables us to use very fine tips. We are able to
+fabricate Ti/TiOx line grids with 18 nm period and well defined isolating
+barriers as small as 15 nm. These junctions show a non-linear current-voltage
+characteristic and an exponential dependence of the conductance on the oxide
+width, indicating tunneling as the dominant conduction mechanism. From the
+conductance - barrier width dependence we derive a barrier height of 178 meV.
+Numerical calculations of the lateral field distribution for different tip
+geometries allow to design the optimum tip for the most localised electric
+field. The electron-beam-deposition (EBD) technique makes it possible to
+actually produce tips of the desired geometry.",9805350v1
+1998-11-06,Structure and oxidation kinetics of the Si(100)-SiO2 interface,"We present first-principles calculations of the structural and electronic
+properties of Si(001)-SiO2 interfaces. We first arrive at reasonable structures
+for the c-Si/a-SiO2 interface via a Monte-Carlo simulated annealing applied to
+an empirical interatomic potential, and then relax these structures using
+first-principles calculations within the framework of density-functional
+theory. We find a transition region at the interface, having a thickness on the
+order of 20\AA, in which there is some oxygen deficiency and a corresponding
+presence of sub-oxide Si species (mostly Si^+2 and Si^+3). Distributions of
+bond lengths and bond angles, and the nature of the electronic states at the
+interface, are investigated and discussed. The behavior of atomic oxygen in
+a-SiO2 is also investigated. The peroxyl linkage configuration is found to be
+lower in energy than interstitial or threefold configurations. Based on these
+results, we suggest a possible mechanism for oxygen diffusion in a-SiO2 that
+may be relevant to the oxidation process.",9811098v1
+1999-03-23,X-ray photoelectron 3s spectra of transition metal oxides,"We present metal 3s x-ray photoelectron spectra of different transition metal
+oxides. The values of the 3s exchange splitting for the 3d metal oxides are
+given as a function of the 3d electron number in the ground state. The spectra
+were analysed using the simple two-configuration model of the interatomic
+configuration mixing. The change of the 3s spectra is ascribed to the change of
+the charge-transfer energy.",9903354v1
+1999-11-12,Temperature-Dependent Pseudogaps in Colossal Magnetoresistive Oxides,"Direct electronic structure measurements of a variety of the colossal
+magnetoresistive oxides show the presence of a pseudogap at the Fermi energy
+E_F which drastically suppresses the electron spectral function at E_F. The
+pseudogap is a strong function of the layer number of the samples (sample
+dimensionality) and is strongly temperature dependent, with the changes
+beginning at the ferromagnetic transition temperature T_c. These trends are
+consistent with the major transport trends of the CMR oxides, implying a direct
+relationship between the pseudogap and transport, including the ""colossal""
+conductivity changes which occur across T_c. The k-dependence of the
+temperature-dependent effects indicate that the pseudogap observed in these
+compounds is not due to the extrinsic effects proposed by Joynt.",9911189v1
+2000-03-16,"Structural properties and quasiparticule energies of cubic SrO, MgO and SrTiO3","The structural properties and the band structures of the charge-transfer
+insulating oxides SrO, MgO and SrTiO3 are computed both within density
+functional theory in the local density approximation (LDA) and in the Hedin's
+GW scheme for self-energy corrections, by using a model dielectric function,
+which approximately includes local field and dynamical effects. The deep
+valence states are shifted by the GW method to higher binding energies, in very
+good agreement with photoemission spectra. Since in all of these oxides the
+direct gaps at high-symmetry points of the Brillouin zone may be very sensitive
+to the actual value of the lattice parameter a, already at the LDA level,
+self-energy corrections are computed both at the theoretical and the
+experimental a. For MgO and SrO, the values of the transition energies between
+the valence and the conduction bands are improved by GW corrections, while for
+SrTiO3 they are overestimated. The results are discussed in relation to the
+importance of local field effects and to the nature of the electronic states in
+these insulating oxides.",0003275v1
+2001-05-26,Discrete saturation thickness and anomalous potential height of native ultrathin aluminum oxide tunnel barriers,"We have investigated planar metal - insulator - metal tunnel junctions with
+aluminum oxide as dielectricum. These oxide barriers were grown on an aluminum
+electrode in pure oxygen at room temperature till saturation. We observed
+discrete barrier widths separated by \Delta s \approx 0.38 nm, corresponding to
+the addition of one layer of oxygen atoms. The minimum thickness of s_0 \approx
+0.54 nm is due to a double layer of oxygen. We found a strong and systematic
+dependence of the barrier height \Phi_0 on the thickness s like \Phi_0 \approx
+2.5 eV / s^2(nm), which nearly coincides with the kinetic electron energy E =
+h^2/2ms^2 for which the deBroglie wavelength matches the width of the barrier.",0105511v1
+2002-02-06,Thermoelectric properties of the brownmillerite oxide Ca_{2-y}La_yCo_{2-x}Al_xO_5,"We prepared the brownmillerite oxide Ca_{2-y}La_yCo_{2-x}Al_xO_5, and found
+that it was an n-type conductor. The thermopower and the resistivity of the
+single crystal are -90 microV/K and 68 mOhm cm along the ab direction at 440 K,
+which suggest relatively good thermoelectrical properties, compared with other
+transition-metal oxides. Their temperature dependences are of activation type,
+and the activation energies are 0.2 eV for the resistivity and 0.04 eV for the
+thermopower. These energies differ by one order in magnitude, which implies
+that a polaron dominates the charge transport. A sign of the thermopower of the
+polycrystals changes from negative to positive at 500 K, indicating that holes
+are excited thermally to decrease the magnitude of thermopower.",0202087v1
+2002-02-07,Statistical properties of charged interfaces,"We consider the equilibrium statistical properties of interfaces submitted to
+competing interactions; a long-range repulsive Coulomb interaction inherent to
+the charged interface and a short-range, anisotropic, attractive one due to
+either elasticity or confinement. We focus on one-dimensional interfaces such
+as strings. Model systems considered for applications are mainly aggregates of
+solitons in polyacetylene and other charge density wave systems, domain lines
+in uniaxial ferroelectrics and the stripe phase of oxides. At zero temperature,
+we find a shape instability which lead, via phase transitions, to tilted
+phases. Depending on the regime, elastic or confinement, the order of the
+zero-temperature transition changes. Thermal fluctuations lead to a pure
+Coulomb roughening of the string, in addition to the usual one, and to the
+presence of angular kinks. We suggest that such instabilities might explain the
+tilting of stripes in cuprate oxides. The 3D problem of the charged wall is
+also analyzed. The latter experiences instabilities towards various tilted
+phases separated by a tricritical point in the elastic regime. In the
+confinement regime, the increase of dimensionality favors either the melting of
+the wall into a Wigner crystal of its constituent charges or a strongly
+inclined wall which might have been observed in nickelate oxides.",0202122v2
+2002-07-06,Charge transfer in molecular conductors -- oxidation or reduction?,"We discuss the nature of charge transfer in molecular conductors upon
+connecting to two metallic contacts and imposing a voltage bias across them.
+The sign of the charge transfer (oxidation vs. reduction) depends on the
+position of the metal Fermi energy with respect to the molecular levels. In
+addition, the charge transfer depends on the strength of the coupling
+(chemisorption vs. physisorption) with the contacts. A convenient way to
+establish the nature and onset of the charge transfer and the corresponding
+features in the I-V is to draw an energy level diagram for each spin species.
+Starting from such a level diagram, we argue that transport in the Tour-Reed
+switching molecules, which consist of a central phenyl ring with a nitroamine
+redox center, involves the oxidation of a highest occupied molecular orbital
+(HOMO)-based level.",0207174v1
+2002-09-25,Nanoscale Electric Phenomena at Oxide Surfaces and Interfaces by Scanning Probe Microscopy,"Scanning Probe Microscopy is used to study and quantify the nanoscale
+electric phenomena in the two classes of oxide systems, namely transport at
+electroactive grain boundaries and surface behavior of ferroelectric materials.
+Scanning Impedance Microscopy is developed to study the capacitance and local
+C-V characteristic of the interfaces combining the spatial resolution of
+traditional SPMs with the precision of conventional electrical measurements.
+SPM of SrTiO3 grain boundaries in conjunction with variable temperature
+impedance spectroscopy and I-V measurements allowed to find and theoretically
+justify the effect of field suppression of dielectric constant in the vicinity
+of the electroactive interfaces in strontium titanate. Similar approaches were
+used to study ferroelectric properties and ac and dc transport behavior in a
+number of polycrystalline oxides.
+  In the second part, the effects of local charge density on the chemistry and
+physics of ferroelectric surfaces are studied. The kinetics and thermodynamics
+parameters of adsorption are assessed by variable temperature SPM.
+Piezoresponse force microscopy is used to engineer domain patterns on
+ferroelectric surfaces. Localized photochemical activity of ferroelectric
+surfaces is explored as a new tool for metallic nanostructures fabrication.",0209599v1
+2002-09-30,Nanoscale Phase Separation in Colossal Magnetoresistance Materials: A Lesson for the Cuprates?,"A recent vast experimental and theoretical effort in manganites has shown
+that the colossal magnetoresistance effect can be understood based on the
+competition of charge-ordered and ferromagnetic phases. The general aspects of
+the theoretical description appear to be valid for any compound with intrinsic
+phase competition. In high temperature superconductors, recent experiments have
+shown the existence of intrinsic inhomogeneities in many materials, revealing a
+phenomenology quite similar to that of manganese oxides. Here, the results for
+manganites are briefly reviewed with emphasis on the general aspects. In
+addition, theoretical speculations are formulated in the context of Cu-oxides
+by mere analogy with manganites. This includes a tentative explanation of the
+spin-glass regime as a mixture of antiferromagnetic and superconducting
+islands, the rationalization of the pseudogap temperature T* as a Griffiths
+temperature where clusters start forming upon cooling, the prediction of
+""colossal"" effects in cuprates, and the observation that quenched disorder may
+be far more relevant in Cu-oxides than previously anticipated.",0209689v2
+2002-11-23,Two-dimensional charge order in layered 2-1-4 perovskite oxides,"Monte Carlo simulations are performed on the three-dimensional (3D) Ising
+model with the 2-1-4 layered perovskite structure as a minimal model for
+checkerboard charge ordering phenomena in layered perovskite oxides. Due to the
+interlayer frustration, only 2D long-range order emerges with a finite
+correlation length along the c axis. Critical exponents of the transition
+change continuously as a function of the interlayer coupling constant. The
+interlayer long-range Coulomb interaction decays exponentially and is
+negligible even between the second-neighbor layers. Instead, monoclinic
+distortion of a tetragonal unit cell lifts the macroscopic degeneracy to induce
+a 3D charge ordering. The dimensionality of the charge order in
+La$_{0.5}$Sr$_{1.5}$MnO$_4$ is discussed from this viewpoint.",0211520v2
+2003-03-06,Vibrational dynamics of solid poly(ethylene oxide),"Molecular dynamics (MD) simulations of crystalline poly(ethylene oxide) (PEO)
+have been carried out in order to study its vibrational properties. The
+vibrational density of states has been calculated using a normal mode analysis
+(NMA) and also through the velocity autocorrelation function of the atoms.
+Results agree well with experimental spectroscopic data. System size effects in
+the crystalline state, studied through a comparison between results for 16 unit
+cells and that for one unit cell has shown important differences in the
+features below 100 cm^-1. Effects of interchain interactions are examined by a
+comparison of the spectra in the condensed state to that obtained for an
+isolated oligomer of ethylene oxide. Calculations of the local character of the
+modes indicate the presence of collective excitations for frequencies lower
+than 100 cm^-1, in which around 8 to 12 successive atoms of the polymer
+backbone participate. The backbone twisting of helical chains about their long
+axes is dominant in these low frequency modes.",0303102v2
+2003-05-13,Why is a noble metal catalytically active? The role of the O-Ag interaction in the function of silver as an oxidation catalyst,"Extensive density-functional theory calculations, and taking into account
+temperature and pressure, affords a comprehensive picture of the behavior and
+interaction of oxygen and Ag(111), and provides valuable insight into the
+function of silver as an oxidation catalyst. The obtained phase-diagram reveals
+the most stable species present in a given environment and thus identifies (and
+excludes) possibly active oxygen species. In particular, for the conditions of
+ethylene epoxidation, a thin oxide-like structure is most stable, suggesting
+that such atomic O species are actuating the catalysis, in contrast to hitherto
+proposed molecular-like species.",0305297v1
+2003-05-24,Studies on La2-xPrxCayBa2Cu4+yOz (0.1 < x < 0.5) type mixed oxide superconductors,"The La2-xPrxCayBa2Cu4+yOz (LaPrCaBCO) mixed oxides have been studied for
+their structural and superconducting properties using X-ray diffraction (XRD),
+d. c. resistivity, d. c. susceptibility and iodometric double titration. All
+the LaPrCaBCO samples for x = 0.1 - 0.5, exhibit tetragonal crystalline
+structure with P 4/mmm space group as determined by Rietveld analysis of the
+X-ray diffraction data. With increasing x, enhancement in Tc is observed, which
+is quite interesting for Pr substituted high Tc oxides. Maximum Tc ~ 58 K has
+been observed for x = 0.5(La-2125 stoichiometry). The results of structural
+studies and superconducting property measurements are presented in light of
+increase in Tc in LaPrCaBCO system with increasing Pr concentration.",0305579v1
+2003-05-30,A Low-Temperature Atomic Layer Deposition Liftoff Method for Microelectronic and Nanoelectronic Applications,"We report a novel method for depositing patterned dielectric layers with
+sub-micron features using atomic layer deposition (ALD). The patterned films
+are superior to sputtered or evaporated films in continuity, smoothness,
+conformality, and minimum feature size. Films were deposited at 100-150C using
+several different precursors and patterned using either PMMA or photoresist.
+The low deposition temperature permits uniform film growth without significant
+outgassing or hardbaking of resist layers. A liftoff technique presented here
+gives sharp step edges with edge roughness as low as ~10 nm. We also measure
+dielectric constants (k) and breakdown fields for the high-k materials aluminum
+oxide (k ~ 8-9), hafnium oxide (k ~ 16-19) and zirconium oxide (k ~ 20-29),
+grown under similar low temperature conditions.",0305711v2
+2003-07-02,O adsorption and incipient oxidation of the Mg(0001) surface,"First principles density functional calculations are used to study the early
+oxidation stages of the Mg(0001) surface for oxygen coverages 1/16 <= Theta <=
+3 monolayers. It is found that at very low coverages O is incorporated below
+the topmost Mg layer in tetrahedral sites. At higher oxygen-load the binding in
+on-surface sites is increased but at one monolayer coverage the on-surface
+binding is still about 60 meV weaker than for subsurface sites. The subsurface
+octahedral sites are found to be unfavorable compared to subsurface tetrahedral
+sites and to on-surface sites. At higher coverages oxygen adsorbs both under
+the surface and up. Our calculations predict island formation and clustering of
+incorporated and adsorbed oxygen in agreement with previous calculations. The
+calculated configurations are compared with the angle-scanned x-ray
+photoelectron diffraction experiment to determine the geometrical structure of
+the oxidized Mg(0001) surface.",0307038v1
+2003-08-14,Effect of interface bonding on spin-dependent tunneling from the oxidized Co surface,"We demonstrate that the factorization of the tunneling transmission into the
+product of two surface transmission functions and a vacuum decay factor allows
+one to generalize Julliere's formula and explain the meaning of the ``tunneling
+density of states'' in some limiting cases. Using this factorization we
+calculate spin-dependent tunneling from clean and oxidized fcc Co surfaces
+through vacuum into Al using the principal-layer Green's function approach. We
+demonstrate that a monolayer of oxygen on the Co (111) surface creates a
+spin-filter effect due to the Co-O bonding which produces an additional
+tunneling barrier in the minority-spin channel. This changes the minority-spin
+dominated conductance for the clean Co surface into a majority spin dominated
+conductance for the oxidized Co surface.",0308268v2
+2003-08-25,Polarons in Complex Oxides and Molecular Nanowires,"There is a growing understanding that transport properties of complex oxides
+and individual molecules are dominated by polaron physics. In superconducting
+oxides the long-range Froehlich and short-range Jahn-Teller electron-phonon
+interactions bind carriers into real space pairs - small bipolarons with
+surprisingly low mass but sufficient binding energy, while the long-range
+Coulomb repulsion keeps bipolarons apart preventing their clustering. The
+bipolaron theory numerically explains high Tc values without any fitting
+parameters and describes other key features of the cuprates. The same approach
+provides a new insite into the theory of transport through molecular nanowires
+and quantum dots (MQD). Attractive polaron-polaron correlations lead to a
+""switching"" phenomenon in the current-voltage characteristics of MQD. The
+degenerate MQD with strong electron-vibron coupling has two stable current
+states (a volatile memory), which might be useful in molecular electronics.",0308489v1
+2004-02-18,Oxidation State of Cobalt in the NaxCoO2-d yH2O Superconductor,"Here we present results of accurate wet-chemical redox analyses, revealing
+that the oxidation number of cobalt in the newly discovered CoO2-layer
+superconductor, NaxCoO2 yH2O (x ~ 0.36, y ~ 1.3) is ~ 3.46. This value is
+significantly lower than the one (~ 3.64) expected on the basis of the value
+determined for the Na to Co stoichiometry ratio, x. The ""lower-than-expected""
+value for the Co oxidation state may be alternatively explained by presence of
+oxygen vacancies or excess protons. Moreover, the result implies that rather
+than an electron-doped Co(IV) lattice the phase should be considered as a
+hole-doped Co(III) lattice.",0402484v1
+2004-02-27,Field-Induced Resistive Switching in Metal-Oxide Interfaces,"We investigate the polarity-dependent field-induced resistive switching
+phenomenon driven by electric pulses in perovskite oxides. Our data show that
+the switching is a common occurrence restricted to an interfacial layer between
+a deposited metal electrode and the oxide. We determine through impedance
+spectroscopy that the interfacial layer is no thicker than 10 nm and that the
+switch is accompanied by a small capacitance increase associated with charge
+accumulation. Based on interfacial I-V characterization and measurement of the
+temperature dependence of the resistance, we propose that a field-created
+crystalline defect mechanism, which is controllable for devices, drives the
+switch.",0402687v1
+2004-04-07,Hopping versus bulk conductivity in transparent oxides: 12CaO.7Al2O3,"First-principles calculations of the mayenite-based oxide,
+[Ca12Al14O32]{2+}(2e-), reveal the mechanism responsible for its high
+conductivity. A detailed comparison of the electronic and optical properties of
+this material with those of the recently discovered novel transparent
+conducting oxide, H-doped UV-activated Ca12Al14O33, allowed us to conclude that
+the enhanced conductivity in [Ca12Al14O32]{2+}(2e-) is achieved by elimination
+of the Coulomb blocade of the charge carriers. This results in a transition
+from variable range hopping behavior with a Coulomb gap in H-doped
+UV-irradiated Ca12Al14O33 to bulk conductivity in [Ca12Al14O32]{2+}(2e-).
+Further, the high degree of the delocalization of the conduction electrons
+obtained in [Ca12Al14O32]{2+}(2e-) indicate that it cannot be classified as an
+electride, originally suggested.",0404187v1
+2004-05-12,A novel route to phase formation of cobalt oxyhydrates using KMnO4 as an oxidizing agent,"We have first succeefully synthesized the sodium cobalt oxyhydrate
+superconductors using KMnO4 as a de-intercalating and oxidizing agent. It is a
+novel route to form the superconductive phase of NaxCoO2.yH2O without resorting
+to the commonly used Br2/CH3CN solution. The role of the KMnO4 is to
+de-intercalate the Na+ from the parent compound Na0.7CoO2 and oxidize the Co
+ion as a result. The higher molar ratio of KMnO4 relative to the sodium content
+tends to remove more Na+ from the parent compound and results in a slight
+expansion of the c-axis in the unit cell. The superconducting transition
+temperature is 4.6-3.8 K for samples treated by the aqueous KMnO4 solution with
+the molar ratio of KMnO4 relative to the sodium content in the range of 0.3 and
+2.29.",0405244v1
+2004-07-08,Surface Chemistry and Electrical Properties of Germanium Nanowires,"Germanium nanowires with p- and n-dopants were synthesized by chemical vapor
+deposition and used to construct complementary field effect transistors .
+Electrical transport and x-ray photoelectron spectroscopy data are correlated
+to glean the effects of Ge surface chemistry to the electrical characteristics
+of GeNWs. Large hysteresis due to water molecules strongly bound to GeO2 on
+GeNWs is revealed. Different oxidation behavior and hysteresis characteristics
+and opposite band bending due to Fermi level pinning by interface states
+between Ge and surface oxides are observed for p- and n-type GeNWs. Vacuum
+annealing above 400C is used to remove surface oxides and eliminate hysteresis
+in GeNW FETs. High-k dielectric HfO2 films grown on clean GeNW surfaces by
+atomic layer deposition (ALD) using an alkylamide precursor is effective
+serving as the first layer of surface passivation. Lastly, the depletion length
+along the radial direction of nanowires is evaluated. The result suggests that
+surface effects could be dominant over the bulk properties of small diameter
+wires.",0407186v1
+2004-07-22,Strongly Enhanced Thermal Stability of Crystalline Organic Thin Films Induced by Aluminum Oxide Capping Layers,"We show that the thermal stability of thin films of the organic semiconductor
+diindenoperylene (DIP) can be strongly enhanced by aluminum oxide capping
+layers. By thermal desorption spectroscopy and in-situ X-ray diffraction we
+demonstrate that organic films do not only stay on the substrate, but even
+remain crystalline up to 460C, i.e. 270 deg. above their desorption point for
+uncapped films (190C). We argue that this strong enhancement of the thermal
+stability compared to uncapped and also metal-capped organic layers is related
+to the very weak diffusion of aluminum oxide and the structurally well-defined
+as-grown interfaces. We discuss possible mechanisms for the eventual breakdown
+at high temperatures.",0407588v1
+2004-07-29,Structural Distortion and Disappearance of Layer Ordering in LixCoO2x2H2O,"The structure of a new member of the AxCoO2 x nH2O family (A=Li,Na,K) was
+determined by high-resolution synchrotron X-ray powder diffraction. Layered
+lithium cobalt oxide hydrate LixCoO2 x 2H2O crystallizes in a disordered
+monoclinic structure (space group C2/m) with lattice parameters a = 4.8915(2)
+A, b = 2.8239(1) A, c = 10.7033(9) A, beta = 112.386(4)deg. Unlike the
+superconducting sodium cobalt oxide hydrate, this material possesses a
+structure with lithium-water layers intercalated between disordered octahedral
+sheets of cobalt oxide. The interlayer spacing is slightly larger (~0.9%) due
+to the higher water content, and one of the two lithium sites extends into the
+water layer. This material shows no superconducting transition above 2K.",0407778v1
+2005-01-28,High-Performance Carbon Nanotube Field-Effect Transistor with Tunable Polarities,"State-of-the-art carbon nanotube field-effect transistors (CNFETs) behave as
+Schottky barrier (SB)-modulated transistors. It is known that vertical scaling
+of the gate oxide significantly improves the performance of these devices.
+However, decreasing the oxide thickness also results in pronounced ambipolar
+transistor characteristics and increased drain leakage currents. Using a novel
+device concept, we have fabricated high-performance, enhancement-mode CNFETs
+exhibiting n or p-type unipolar behavior, tunable by electrostatic and/or
+chemical doping, with excellent OFF-state performance and a steep subthreshold
+swing (S =63 mV/dec). The device design allows for aggressive oxide thickness
+and gate length scaling while maintaining the desired device characteristics.",0501690v1
+2005-03-22,Improvement of current-control induced by oxide crenel in very short field-effect-transistor,"A 2D quantum ballistic transport model based on the non-equilibrium Green's
+function formalism has been used to theoretically investigate the effects
+induced by an oxide crenel in a very short (7 nm) thin-film
+metal-oxide-semiconductor-field-effect-transistor. Our investigation shows that
+a well adjusted crenel permits an improvement of on-off current ratio Ion/Ioff
+of about 244% with no detrimental change in the drive current Ion. This
+remarkable result is explained by a nontrivial influence of crenel on
+conduction band-structure in thin-film. Therefore a well optimized crenel seems
+to be a good solution to have a much better control of short channel effects in
+transistor where the transport has a strong quantum behavior.",0503556v1
+2005-04-12,"First-principles study of cubic perovskites SrMO_3 (M = Ti, V, Zr and Nb)","Using the full-potential linearized-augmented-plane-wave (FLAPW) method, we
+have analyzed systematically the trends in the structural and electronic
+properties of the 3d and 4d transition-metal oxides SrMO_3 (M = Ti, V, Zr and
+Nb). The optimized lattice parameters, bulk modules, densities of states, band
+structures and charge density distributions are obtained and compared with the
+available theoretical and experimental data. The energy gap between O2p - Md
+bands increases as the covalency of the system decreases going from 3d to 4d
+based perovskites. The electron configurations of Sr(Ti,Zr)O_3 and Sr(V,Nb)O_3
+usually referred to as d^0 and d^1 oxides, respectively, differ considerably
+from these idealized ""ionic"" configurations, and the deviations increase with
+increasing of the d-p covalent overlap in the oxides.",0504286v1
+2005-05-06,Oxygen diffusion in nanostructured perovskites,"Nonstoichiometric perovskite-related oxides (such as ferrites and cobaltites,
+etc.) are characterized by fast oxygen transport at ambient temperatures, which
+relates to the microstructural texturing of these materials, consisting wholly
+of nanoscale microdomains.
+  We have developed an inhomogeneous diffusion model to describe the kinetics
+of oxygen incorporation into nanostructured oxides. Nanodomain boundaries are
+assumed to be the high diffusivity paths for oxygen transport whereas diffusion
+into the domains proceeds much slower. Using Laplace transform methods, an
+exact solution is found for a ramped stepwise potential, allowing fitting of
+the experimental data to theoretical curves (in Laplace transforms).
+  A further model generalization is considered by introducing additional
+parameters for the size distribution of domains and particles.
+  The model has been applied for qualitative evaluation of oxygen diffusion
+parameters from the data on wet electrochemical oxidation of nano-structured
+perovskite SrCo_0.5Fe_0.2Ta_0.3O_{3-y} samples.",0505149v2
+2005-06-01,Selective epitaxial growth of sub-micron complex oxide structures by amorphous SrTiO3,"A chemical-free technique for fabricating submicron complex oxide structures
+has been developed based on selective epitaxial growth. The crystallinity and
+hence the conductivity of the complex oxide is inhibited by amorphous SrTiO3
+(STO). Using a combination of pulsed laser deposition and electron-beam
+lithography, amorphous STO barriers are first deposited on a single crystal
+substrate. A thin film is then deposited on the patterned substrate with the
+amorphous STO barriers acting to electrically and physically isolate different
+regions of the film. Since no chemical or physical etchants come in contact
+with the deposited film, its integrity and stability are preserved. This
+technique has successfully produced sub-micron YBCO and LCMO structures.",0506001v1
+2005-09-08,Real-time observation of non-equilibrium liquid condensate confined at tensile crack tips in oxide glasses,"Since crack propagation in oxide materials at low crack velocities is partly
+determined by chemical corrosion, proper knowledge of the crack tip chemistry
+is crucial for understanding fracture in these materials. Such knowledge can be
+obtained only from in situ studies because the processes that occur in the
+highly confined environment of the crack tip are very different from those that
+take place at free surfaces, or that can be traced post mortem. We report the
+occurrence of hydrous liquid condensate between the two fracture surfaces in
+the vicinity of the tip of tensile cracks in silica. Observations are performed
+in real-time by means of atomic force microscopy (AFM) at continuously
+controlled crack velocities in the regime of stress corrosion. Condensate
+formation and changes in extent and shape are demonstrated for a wide range of
+macroscopic humidity at different crack speeds. Its liquid character is
+confirmed by the study of AFM phase-contrast data. It is believed that this
+evidence of a nanoscale liquid hydrous phase at the crack tip will enable novel
+insights in the chemistry of failure of oxide materials.",0509209v1
+2007-01-15,Microscopic annealing process and its impact on superconductivity in T'-structure electron-doped copper oxides,"High-transition-temperature superconductivity arises in copper oxides when
+holes or electrons are doped into the CuO2 planes of their insulating parent
+compounds. While hole-doping quickly induces metallic behavior and
+superconductivity in many cuprates, electron-doping alone is insufficient in
+materials such as R2CuO4 (R is Nd, Pr, La, Ce, etc.), where it is necessary to
+anneal an as-grown sample in a low-oxygen environment to remove a tiny amount
+of oxygen in order to induce superconductivity. Here we show that the
+microscopic process of oxygen reduction repairs Cu deficiencies in the as-grown
+materials and creates oxygen vacancies in the stoichiometric CuO2 planes,
+effectively reducing disorder and providing itinerant carriers for
+superconductivity. The resolution of this long-standing materials issue
+suggests that the fundamental mechanism for superconductivity is the same for
+electron- and hole-doped copper oxides.",0701345v1
+2007-02-26,Nonpolar resistance switching of metal/binary-transition-metal oxides/metal sandwiches: homogeneous/inhomogeneous transition of current distribution,"Exotic features of a metal/oxide/metal (MOM) sandwich, which will be the
+basis for a drastically innovative nonvolatile memory device, is brought to
+light from a physical point of view. Here the insulator is one of the
+ubiquitous and classic binary-transition-metal oxides (TMO), such as Fe2O3,
+NiO, and CoO. The sandwich exhibits a resistance that reversibly switches
+between two states: one is a highly resistive off-state and the other is a
+conductive on-state. Several distinct features were universally observed in
+these binary TMO sandwiches: namely, nonpolar switching, non-volatile threshold
+switching, and current--voltage duality. From the systematic sample-size
+dependence of the resistance in on- and off-states, we conclude that the
+resistance switching is due to the homogeneous/inhomogeneous transition of the
+current distribution at the interface.",0702564v1
+2007-03-28,Electronic parameters for the hole transfer in DNA duplex oligomers,"We report on our calculations of the inner-sphere reorganization energy and
+the interaction of the pi orbitals within DNA oligomers. The exponential
+decrease of the electronic coupling between the highest and second highest
+occupied base orbitals of the intrastrand nucleobases in the (A-T)n and (G-C)n
+oligomers have been found with an increase of the sequence number n in the DNA
+structure. We conclude that for realistic estimation of the electronic coupling
+values between the nucleobases within the DNA molecule, a DNA chain containing
+at least four base pairs is required. We estimate the geometry relaxation of
+the base pairs within the (A-T)n and (G-C)n oligomers (n=1-6) due to their
+oxidation. The decrease of the inner-sphere reorganization energy with
+elongation of the oligomer structure participating in the oxidation process
+have been observed. The maximum degree of geometry relaxation of the nucleobase
+structures and correspondingly the higher charge density in the oxidized state
+are found to be located close to the oligomer center.",0703764v1
+2002-12-04,Oxidation = group theory,"Dimensional reduction of theories involving (super-)gravity gives rise to
+sigma models on coset spaces of the form G/H, with G a non-compact group, and H
+its maximal compact subgroup. The reverse process, called oxidation, is the
+reconstruction of the possible higher dimensional theories, given the lower
+dimensional theory. In 3 dimensions, all degrees of freedom can be dualized to
+scalars. Given the group G for a 3 dimensional sigma model on the coset G/H, we
+demonstrate an efficient method for recovering the higher dimensional theories,
+essentially by decomposition into subgroups. The equations of motion, Bianchi
+identities, Kaluza-Klein modifications and Chern-Simons terms are easily
+extracted from the root lattice of the group G. We briefly discuss some aspects
+of oxidation from the E_{8(8)}/SO(16) coset, and demonstrate that our formalism
+reproduces the Chern-Simons term of 11-d supergravity, knows about the
+T-duality of IIA and IIB theory, and easily deals with self-dual tensors, like
+the 5-tensor of IIB supergravity.",0212050v1
+2004-12-09,Zirconium oxidation under high energy heavy ion irradiation,"This paper concerns the study of zirconium oxidation under irradiation with
+high energetic Xe ions. The irradiations were performed on the IRRSUD beam line
+at GANIL (Caen). The oxygen partial pressure was fixed at 10$^{-3}$ Pa and two
+temperature conditions were used, either 480$\circ$C reached by Joule effect
+heating or 280$\circ$C due to Xe energy deposition. Zirconia was fully
+characterized by Rutherford Backscattering Spectrometry, Transmission Electron
+Microscopy and Grazing Angle X-ray Diffraction. Apparent diffusion coefficients
+of oxygen in ZrO2 were determined from these experiments by using a model which
+takes into account a surface exchange between oxygen gas and the ZrO2 surface.
+These results are compared with thermal oxidation data.",0412056v1
+2002-08-31,Oxide-Semiconductor Materials for Quantum Computation,"Scalable fault-tolerant quantum computer architectures require quantum gates
+that operate within a small fraction of the qubit decoherence time and with
+high accuracy over a bandwidth set by the decoherence rate. Electron spin
+quantum bits in Si are promising because of long decoherence times (~0.5 ms),
+but electrical gating schemes still seem problematic. Oxide-semiconductor
+heterostructures have the potential for precise electrical control of gate
+operations in the semiconductor, using optical rectification in the
+ferroelectric oxide. Accurate (~80 dB), local (~10 nm), dynamic (>THz) and
+programmable optical control over electric polarization in the ferroelectric
+can be achieved using existing technology. Optical techniques may also be
+useful in rapid initialization of the quantum computer, and for providing a
+source of initialized qubits to use for quantum error correction. Advantages of
+optical methods will be discussed within a framework proposed for a quantum
+information processor using ferroelectrically coupled electron spins and Ge
+quantum dots in Si.",0209008v1
+2007-04-06,Millimeter-Thick Single-Walled Carbon Nanotube Forests: Hidden Role of Catalyst Support,"A parametric study of so-called ""super growth"" of single-walled carbon
+nanotubes(SWNTs) was done by using combinatorial libraries of iron/aluminum
+oxide catalysts. Millimeter-thick forests of nanotubes grew within 10 min, and
+those grown by using catalysts with a thin Fe layer (about 0.5 nm) were SWNTs.
+Although nanotube forests grew under a wide range of reaction conditions such
+as gas composition and temperature, the window for SWNT was narrow. Fe
+catalysts rapidly grew nanotubes only when supported on aluminum oxide.
+Aluminum oxide, which is a well-known catalyst in hydrocarbon reforming, plays
+an essential role in enhancing the nanotube growth rates.",0704.0915v1
+2007-04-11,Unconventional approaches to combine optical transparency with electrical conductivity,"Combination of electrical conductivity and optical transparency in the same
+material -- known to be a prerogative of only a few oxides of post-transition
+metals, such as In, Sn, Zn and Cd -- manifests itself in a distinctive band
+structure of the transparent conductor host. While the oxides of other elements
+with $s^2$ electronic configuration, for example, Mg, Ca, Sc and Al, also
+exhibit the desired optical and electronic features, they have not been
+considered as candidates for achieving good electrical conductivity because of
+the challenges of efficient carrier generation in these wide-bandgap materials.
+Here we demonstrate that alternative approaches to the problem not only allow
+attaining the transport and optical properties which compete with those in
+currently utilized transparent conducting oxides (TCO), but also significantly
+broaden the range of materials with a potential of being developed into novel
+functional transparent conductors.",0704.1494v1
+2007-04-11,Averaging of the electron effective mass in multicomponent transparent conducting oxides,"We find that layered materials composed of various oxides of cations with
+$s^2$ electronic configuration, $XY_2$O$_4$, $X$=In or Sc, $Y$=Ga, Zn, Al, Cd
+and/or Mg, exhibit isotropic electron effective mass which can be obtained via
+averaging over those of the corresponding single-cation oxide constituents.
+This effect is due to a hybrid nature of the conduction band formed from the
+s-states of {\it all} cations and the oxygen p-states. Moreover, the observed
+insensitivity of the electron effective mass to the oxygen coordination and to
+the distortions in the cation-oxygen chains suggests that similar behavior can
+be expected in technologically important amorphous state. These findings
+significantly broaden the range of materials as efficient transparent conductor
+hosts.",0704.1499v2
+2007-04-15,Ab initio wavefunction based methods for excited states in solids: correlation corrections to the band structure of ionic oxides,"Ab initio wavefunction based methods are applied to the study of electron
+correlation effects on the band structure of oxide systems. We choose MgO as a
+prototype closed-shell ionic oxide. Our analysis is based on a local
+Hamiltonian approach and performed on finite fragments cut from the infinite
+solid. Localized Wannier functions and embedding potentials are obtained from
+prior periodic Hartree-Fock (HF) calculations. We investigate the role of
+various electron correlation effects in reducing the HF band gap and modifying
+the band widths. On-site and nearest-neighbor charge relaxation as well as
+long-range polarization effects are calculated. Whereas correlation effects are
+essential for computing accurate band gaps, we found that they produce smaller
+changes on the HF band widths, at least for this material. Surprisingly, a
+broadening effect is obtained for the O 2p valence bands. The ab initio data
+are in good agreement with the energy gap and band width derived from
+thermoreflectance and x-ray photoemission experiments. The results show that
+the wavefunction based approach applied here allows for well controlled
+approximations and a transparent identification of the microscopic processes
+which determine the electronic band structure.",0704.1906v1
+2007-04-15,Theory of enhanced second-harmonic generation by the quadrupole-dipole hybrid exciton,"We report calculated substantial enhancement of the second harmonic
+generation (SHG) in cuprous oxide crystals resonantly hybridized with an
+appropriate organic material (DCM2:CA:PS 'solid-state solvent'). The quadrupole
+origin of the inorganic part of the quadrupole-dipole hybrid provides inversion
+symmetry breaking and the organic part contributes to the oscillator strength
+of the hybrid. We show that the enhancement of the SHG, compared to bulk
+cuprous oxide crystal, is proportional to the ratio of the DCM2 dipole moment
+and the effective dipole moment of the quadrupole transitions in the cuprous
+oxide. It is also inversely proportional to the line-width of the hybrid and
+bulk excitons. The enhancement may be regulated by adjusting the organic blend
+(mutual concentration of the DCM2 and CA part of the solvent) and pumping
+conditions(varying the angle of incidence in case of optical pumping or
+populating the minimum of the lower branch of the hybrid in case of electrical
+pumping).",0704.1923v3
+2007-05-07,Vibrational Infrared Lifetime of the Anesthetic nitrous oxide gas in solution,"The lifetime of the asymmetric fundamental stretching 2218 cm$^{-1}$
+vibration of the anesthetic gas nitrous oxide (N$_2$O) dissolved in octanol and
+olive oil is reported. These solvents are model systems commonly used to assess
+anesthetic potency. Picosecond time-scale molecular dynamics simulations have
+suggested that protein dynamics or membrane dynamics play a role in the
+molecular mechanism of anesthetic action. Ultrafast infrared spectroscopy with
+100 fs time resolution is an ideal tool to probe dynamics of anesthetic
+molecules on such timescales. Pump-probe studies at the peak of the vibrational
+band yield a lifetime of $55 \pm 1$ ps in olive oil and $52 \pm 1 ps$ in
+octanol. The similarity of lifetimes suggests that energy relaxation of the
+anesthetic is determined primarily by the hydrophobic nature of the
+environment, consistent with models of anesthetic action. The results show that
+nitrous oxide is a good model system for probing anesthetic-solvent
+interactions using nonlinear infrared spectroscopy.",0705.0835v1
+2007-08-03,Hubbard-Thomas-Fermi Theory of Transition Metal Oxide Heterostructures,"We demonstrate that the charge distributions in Hubbard-model representations
+of transition metal oxide heterojucntions can be described by a Thomas-Fermi
+theory in which the energy is approximated as the sum of the electrostatic
+energy and the uniform three-dimensional Hubbard model energy per site at the
+local density equals to a constant. When charged atomic layers in the oxides
+are approximated as two-dimensional sheets with uniform charge density, the
+electrostatic energy is simply evaluated. We find that this Thomas-Fermi theory
+can reproduce results obtained from full Hartree-Fock theory for various
+different heterostructures. We also show explicitly how Thomas-Fermi theory can
+be used to estimate some key properties qualitatively.",0708.0554v1
+2007-08-23,Elliptical hole pockets in the Fermi surfaces of unhydrated and hydrated sodium cobalt oxides,"The surprise discovery of superconductivity below 5K in sodium cobalt oxides
+when hydrated with water has caught the attention of experimentalists and
+theorists alike. Most explanations for its occurence have focused heavily on
+the properties of some small elliptically shaped pockets predicted to be the
+electronically dominant Fermi surface sheet, but direct attempts to look for
+them have instead cast serious doubts over their existence. Here we present
+evidence that these pockets do indeed exist, based on bulk measurements of the
+electron momentum distribution in unhydrated and hydrated sodium cobalt oxides
+using the technique of x-ray Compton scattering.",0708.3133v1
+2007-10-04,Testing the Hydrogen Peroxide-Water Hypothesis for Life on Mars with the TEGA instrument on the Phoenix Lander,"Since Viking has conducted its life detection experiments on Mars, many
+missions have enhanced our knowledge about the environmental conditions on the
+Red Planet. However, the Martian surface chemistry and the Viking lander
+results remain puzzling. Non-biological explanations that favor a strong
+inorganic oxidant are currently favored (e.g., Mancinelli, 1989; Quinn and
+Zent, 1999; Klein, 1999, Yen et al., 2000), but problems remain regarding the
+life time, source, and abundance of that oxidant to account for the Viking
+observations (Zent and McKay, 1994). Alternatively, a hypothesis favoring the
+biological origin of a strong oxidizer has recently been advanced (Houtkooper
+and Schulze-Makuch, 2007). Here, we report about laboratory experiments that
+simulate the experiments to be conducted by the Thermal and Evolved Gas
+Analyzer (TEGA) instrument of the Phoenix lander, which is to descend on Mars
+in May 2008. Our experiments provide a baseline for an unbiased test for
+chemical versus biological responses, which can be applied at the time the
+Phoenix Lander transmits its first results from the Martian surface.",0710.1036v1
+2007-11-12,Electrochemical lithium intercalation in nanosized manganese oxides,"X-ray amorphous manganese oxides were prepared by reduction of sodium
+permanganate by lithium iodide in aqueous medium (MnOx-I) and by decomposition
+of manganese carbonate at moderate temperature (MnOx-C). TEM showed that these
+materials are not amorphous, but nanostructured, with a prominent spinel
+substructure in MnOx-C. These materials intercalate lithium with capacities up
+to 200 mAh/g at first cycle (potential window 1.8-4.3 V) and 175 mAh/g at 100th
+cycle. Best performances for MnOx-C are obtained with cobalt doping. Potential
+electrochemical spectroscopy shows that the initial discharge induces a 2-phase
+transformation in MnOx-C phases, but not in MnOx-I ones. EXAFS and XANES
+confirm the participation of manganese in the redox process, with variations in
+local structure much smaller than in known long-range crystallized manganese
+oxides. X-ray absorption spectroscopy also shows that cobalt in MnOx-C is
+divalent and does not participate in the electrochemical reaction.",0711.1785v1
+2007-12-21,First-principles investigation of Ag-Cu alloy surfaces in an oxidizing environment,"In this paper we investigate by means of first-principles density functional
+theory calculations the (111) surface of the Ag-Cu alloy under varying
+conditions of pressure of the surrounding oxygen atmosphere and temperature.
+This alloy has been recently proposed as a catalyst with improved selectivity
+for ethylene epoxidation with respect to pure silver, the catalyst commonly
+used in industrial applications. Here we show that the presence of oxygen leads
+to copper segregation to the surface. Considering the surface free energy as a
+function of the surface composition, we construct the convex hull to
+investigate the stability of various surface structures. By including the
+dependence of the free surface energy on the oxygen chemical potential, we are
+able compute the phase diagram of the alloy as a function of temperature,
+pressure and surface composition. We find that, at temperature and pressure
+typically used in ethylene epoxidation, a number of structures can be present
+on the surface of the alloy, including clean Ag(111), thin layers of copper
+oxide and thick oxide-like structures. These results are consistent with, and
+help explain, recent experimental results.",0712.3652v1
+2008-01-07,DC transferred arc thermal plasma assisted growth of nanoparticles with different crystalline phases,"The control of the crystalline phases of the nanoparticles grown in a
+direct-current transferred-arc plasma-assisted reactor is reported. The
+crystalline phases of the as synthesized nanoparticles are shown to critically
+depend on the operating gas pressure. The paper reports about the change in the
+crystalline phases of three distinct compounds namely aluminium oxide (Al2O3),
+aluminium nitride (AlN) and iron oxide (FexOy). The major outcome of the
+present work is that the phases having higher defect densities are more
+probable to form at the sub-atmospheric operating pressure. The variations in
+the crystalline structures are discussed on the basis of the equilibrium defect
+density formed during the homogeneous nucleation. The as synthesized
+nanoparticles were examined by X-ray diffraction analysis and transmission
+electron microscopy. In addition, the confirmatory analysis for the crystalline
+phases of the as synthesized iron oxides was carried out with the help of
+Mossbauer spectroscopy.",0801.0945v1
+2008-01-14,Charge transfer in heterostructures of strongly correlated materials,"In this manuscript, recent theoretical investigations by the authors in the
+area of oxide multilayers are briefly reviewed. The calculations were carried
+out using model Hamiltonians and a variety of non-perturbative techniques.
+Moreover, new results are also included here. They correspond to the generation
+of a metallic state by mixing insulators in a multilayer geometry, using the
+Hubbard and Double Exchange models. For the latter, the resulting metallic
+state is also ferromagnetic. This illustrates how electron or hole doping via
+transfer of charge in multilayers can lead to the study of phase diagrams of
+transition metal oxides in the clean limit. Currently, these phase diagrams are
+much affected by the disordering standard chemical doping procedure, which
+introduces quenched disorder in the material.",0801.2174v2
+2008-04-15,Pathways of bond topology transitions at the interface of silicon nanocrystals and amorphous silica matrix,"The interface chemistry of silicon nanocrystals (NCs) embedded in amorphous
+oxide matrix is studied through molecular dynamics simulations with the
+chemical environment described by the reactive force field model. Our results
+indicate that the Si NC-oxide interface is more involved than the previously
+proposed schemes which were based on solely simple bridge or double bonds. We
+identify different types of three-coordinated oxygen complexes, previously not
+noted. The abundance and the charge distribution of each oxygen complex is
+determined as a function of the NC size as well as the transitions among them.
+The oxidation at the surface of NC induces tensile strain to Si-Si bonds which
+become significant only around the interface, while the inner core remains
+unstrained. Unlike many earlier reports on the interface structure, we do not
+observe any double bonds. Furthermore, our simulations and analysis reveal that
+the interface bond topology evolves among different oxygen bridges through
+these three-coordinated oxygen complexes.",0804.2322v1
+2008-05-20,Unification of bulk and interface electroresistive switching in oxide systems,"We demonstrate that the physical mechanism behind electroresistive switching
+in oxide Schottky systems is electroformation, as in insulating oxides.
+Negative resistance shown by the hysteretic current-voltage curves proves that
+impact ionization is at the origin of the switching. Analyses of the
+capacitance-voltage and conductance-voltage curves through a simple model show
+that an atomic rearrangement is involved in the process. Switching in these
+systems is a bulk effect, not strictly confined at the interface but at the
+charge space region.",0805.3159v3
+2008-06-13,Remote hole-doping of Mott insulators on the nanometer scale,"At interfaces between polar and nonpolar perovskite oxides, an unusual
+electron-doping has been previously observed, due to electronic
+reconstructions. We report on remote hole-doping at an interface composed of
+only polar layers, revealed by high-resolution hard x-ray core-level
+photoemission spectroscopy. In LaAlO3/LaVO3/LaAlO3 trilayers, the vanadium
+valence systematically evolves from the bulk value of V3+ to higher oxidation
+states with decreasing LaAlO3 cap layer thickness. These results provide a
+synthetic approach to hole-doping transition metal oxide heterointerfaces
+without invoking a polar discontinuity.",0806.2191v1
+2008-08-25,Nano-Graphene Oxide for Cellular Imaging and Drug Delivery,"Two-dimensional graphene offers interesting electronic, thermal and
+mechanical properties that are currently explored for advanced electronics,
+membranes and composites. Here we synthesize and explore the biological
+application of nano-graphene oxide NGO, single-layer graphene oxide sheets down
+to a few nanometers in lateral width. We develop functionalization chemistry to
+impart solubility and compatibility of NGO in biological environments. We
+obtain size separated pegylated NGO sheets that are soluble in buffers and
+serum without agglomeration. The NGO sheets are found to be photoluminescent in
+the visible and infrared regions. The intrinsic photoluminescence of NGO is
+used for live cell imaging in the near-infrared with little background. We
+found that simple physisorption via pi-stacking can be used for loading
+doxorubicin, a widely used cancer drug onto NGO functionalized with antibody
+for selective cancer cell killing in vitro. Owing to the small size, intrinsic
+optical properties, large specific surface area,low cost, and useful
+non-covalent interactions with aromatic drug molecules, NGO is a promising new
+material for biological and medical applications.",0808.3396v1
+2008-09-11,Modeling of the evolution of dielectric loss with processing temperature in ferroelectric and dielectric thin oxide films,"It was experimentally found that the evolution of dielectric loss with
+processing temperature displays a common trend in ferroelectric and dielectric
+thin oxide films: firstly an increase and then a decrease in dielectric loss
+when the processing temperature is gradually raised. Such a dielectric response
+of ferroelectric/dielectric thin films has been theoretically addressed in this
+work. We propose that at the initial stage of the crystallization process in
+thin films, the transformation from amorphous to crystalline phase should
+increase substantially the dielectric loss; then, with further increase in the
+processing temperature, the coalescent growth of small crystalline grains into
+big ones could be helpful in reducing the dielectric loss by lowering grain
+boundary densities. The obtained experimental data for (Ba,Sr)TiO3 thin films
+with 500 nm in thickness were analyzed in terms of the model developed and
+shown to be in a reasonable agreement with the theoretical results.",0809.2008v1
+2008-09-26,Understanding the nature of electronic effective mass in double-doped SrTiO$_{3}$,"We present an approach to tune the effective mass in an oxide semiconductor
+by a double doping mechanism. We demonstrate this in a model oxide system
+Sr$_{1-x}$La$_x$TiO$_{3-\delta}$, where we can tune the effective mass ranging
+from 6--20$\mathrm{m_e}$ as a function of filling or carrier concentration and
+the scattering mechanism, which are dependent on the chosen lanthanum and
+oxygen vacancy concentrations. The effective mass values were calculated from
+the Boltzmann transport equation using the measured transport properties of
+thin films of Sr$_{1-x}$La$_x$TiO$_{3-\delta}$. Our method, which shows that
+the effective mass decreases with carrier concentration, provides a means for
+understanding the nature of transport processes in oxides, which typically have
+large effective mass and low electron mobility, contrary to the tradional high
+mobility semiconductors.",0809.4706v2
+2008-11-18,Kinetics of the thermal degradation of Erica arborea by DSC: Hybrid kinetic method,"The scope of this work was the determination of kinetic parameters of the
+thermal oxidative degradation of a Mediterranean scrub using a hybrid method
+developed at the laboratory. DSC and TGA were used in this study under air
+sweeping to record oxidative reactions. Two dominating and overlapped
+exothermic peaks were recorded in DSC and individualized using an experimental
+and numerical separation. This first stage allowed obtaining the enthalpy
+variation of each exothermic phenomenon. In a second time, a model free method
+was applied on each isolated curve to determine the apparent activation
+energies. A reactional kinetic scheme was proposed for the global exotherm
+composed of two independent and consecutive reactions. In fine mean values of
+enthalpy variation and apparent activation energy previously determined were
+injected in a model fitting method to obtain the reaction order and the
+preexponential factor of each oxidative reaction. We plan to use these data in
+a sub-model to be integrated in a wildland fire spread model.",0811.2985v1
+2008-11-21,Kinetic study of the oxide-assisted catalyst-free synthesis of silicon nitride nanowires,"The synthesis of Si3N4 nanowires from the reaction of silicon nanoparticles
+with N2 in the 1200-1440 C temperature range is reported. The nitridation
+conditions are such that the reaction with nitrogen is favoured by the presence
+of silicon oxide in the particles and by the active oxidation of silicon
+without a catalyst. It is shown that the Si to Si3N4 conversion rate depends on
+the amount of silicon particles used in the experiments and that, in general,
+the reaction slows down for greater amounts. This trend is explained by
+particle stacking, which restricts the exchange of gases between the furnace
+atmosphere and the atmosphere around the inner particles. In a first stage,
+local oxygen partial pressure increases around the inner particles and inhibits
+nitridation locally. If the amount of reactant Si nanoparticles is small
+enough, this extrinsic effect is avoided and the intrinsic nitridation kinetics
+can be measured. Experiments show that intrinsic kinetics does not depend on
+temperature.",0811.3525v1
+2008-11-29,Fabrication of graphene nanoribbon by local anodic oxidation lithography using atomic force microscope,"We conducted local anodic oxidation (LAO) lithography in single-layer,
+bilayer, and multilayer graphene using tapping-mode atomic force microscope.
+The width of insulating oxidized area depends systematically on the number of
+graphene layers. An 800-nm-wide bar-shaped device fabricated in single-layer
+graphene exhibits the half-integer quantum Hall effect. We also fabricated a
+55-nm-wide graphene nanoribbon (GNR). The conductance of the GNR at the charge
+neutrality point was suppressed at low temperature, which suggests the opening
+of an energy gap due to lateral confinement of charge carriers. These results
+show that LAO lithography is an effective technique for the fabrication of
+graphene nanodevices.",0812.0048v1
+2008-12-11,Difference of Oxide Hetero-Structure Junctions with Semiconductor Electronic Devices,"Charge carrier injection performed in Pr0.7Ca0.3MnO3 (PCMO) hetero-structure
+junctions exhibits stable without electric fields and dramatic changes in both
+resistances and interface barriers, which are entirely different from behaviors
+of semiconductor devices. Disappearance and reversion of interface barriers
+suggest that the adjustable resistance switching of such hetero-structure oxide
+devices should associate with motion of charge carriers across interfaces. The
+results suggested that injected carriers should be still staying in devices and
+resulted in changes in properties, which guided to a carrier self-trapping and
+releasing picture in strongly correlated electronic framework. Observations in
+PCMO and oxygen deficient CeO2 devices show that oxides as functional materials
+could be used in microelectronics with some novel properties, in which
+interface is very important.",0812.2071v1
+2009-01-23,Halving the Casimir force with conductive oxides,"The possibility to modify the strength of the Casimir effect by tailoring the
+dielectric functions of the interacting surfaces is regarded as a unique
+opportunity in the development of Micro- and NanoElectroMechanical Systems. In
+air, however, one expects that, unless noble metals are used, the electrostatic
+force arising from trapped charges overcomes the Casimir attraction, leaving no
+room for exploitation of Casimir force engineering at ambient conditions. Here
+we show that, in the presence of a conductive oxide, the Casimir force can be
+the dominant interaction even in air, and that the use of conductive oxides
+allows one to reduce the Casimir force up to a factor of 2 when compared to
+noble metals.",0901.3720v2
+2009-01-29,The melting behavior of lutetium aluminum perovskite LuAlO3,"DTA measurements with mixtures of aluminum oxide and lutetium oxide around
+the 1:1 perovskite composition were performed up to 1970 deg. C. A peak with
+onset 1901 deg C was due to the melting of the eutectic Lu4Al2O9 (monoclinic
+phase) and LuAlO3 (perovskite). Neither peritectic melting of the perovskite
+nor its decomposition in the solid phase could be resolved experimentally. The
+maximum of the eutectic peak size is near x=0.44, on the Lu-rich side of the
+perovskite, which is consistent with the conclusion that LuAlO3 melts
+peritectically at ca. 1907 deg. C as proposed by Wu, Pelton, J. Alloys Compd.
+179 (1992) 259. Thermodynamic equilibrium calculations reveal, that under
+strongly reducing conditions (oxygen partial pressure <10^{-13} bar)
+aluminum(III) oxide can be reduced to suboxides or even Al metal. It is shown
+that under such conditions a new phase field with liquid Al can appear.",0901.4654v3
+2009-04-22,Modeling Study of the Low-Temperature Oxidation of Large Methyl Esters,"This study focuses on the automatic generation by the software EXGAS of
+kinetic models for the oxidation of large methyl esters using a single set of
+kinetic parameters. The obtained models allow to well reproduce the oxidation
+of n-decane / methyl palmitate mixture in a jet-stirred reactor. This paper
+also presents the construction and a comparison of models for methyl esters
+from C7 up to C17 in terms f conversion in a jet-stirred reactor and of
+ignition delay time in a shock tube. This comparison study showed that methyl
+esters larger than methyl octanoate behave similarly and have very close
+reactivities.",0904.3536v1
+2009-04-30,Polaronic hole localization and multiple hole binding of acceptors in oxide wide-gap semiconductors,"Acceptor-bound holes in oxides often localize asymmetrically at one out of
+several equivalent oxygen ligands. Whereas Hartree-Fock (HF) theory overly
+favors such symmetry-broken polaronic hole-localization in oxides, standard
+local density (LD) calculations suffer from spurious delocalization among
+several oxygen sites. These opposite biases originate from the opposite
+curvatures of the energy as a function of the fractional occupation number n,
+i.e., d2E/dn2 < 0 in HF and d2E/dn2 > 0 in LD. We recover the correct linear
+behavior, d2E/dn2 = 0, that removes the (de)localization bias by formulating a
+generalized Koopmans condition. The correct description of oxygen
+hole-localization reveals that the cation-site nominal single-acceptors in ZnO,
+In2O3, and SnO2 can bind multiple holes.",0905.0018v1
+2009-06-17,Resonant structures based on amorphous silicon sub-oxide doped with Er3+ with silicon nanoclusters for an efficient emission at 1550 nm,"We present a resonant approach to enhance 1550nm emission efficiency of
+amorphous silicon sub-oxide doped with Er3+ (a-SiOx<Er>) layers with silicon
+nanoclusters (Si-NC). Two distinct techniques were combined to provide a
+structure that allowed increasing approximately 12x the 1550nm emission. First,
+layers of SiO2 were obtained by conventional wet oxidation and a-SiOx<Er>
+matrix was deposited by reactive RF co-sputtering. Secondly, an extra pump
+channel (4I15/2 to 4I9/2) of Er3+ was created due to Si-NC formation on the
+same a-SiOx<Er> matrix via a hard annealing at 1150 C. The SiO2 and the
+a-SiOx<Er> thicknesses were designed to support resonances near the pumping
+wavelength (~500nm), near the Si-NC emission (~800nm) and near the a-SiOx<Er>
+emission (~1550nm) enhancing the optical pumping process.",0906.3274v1
+2009-07-02,"Spin, Orbital, and Spin-Orbital Polarons in Transition Metal Oxides","I give a brief overview of a polaron formation in three distinct transition
+metal oxides: (i) spin polaron when a hole is added to the antiferromagnetic
+(AF) ordered plane in La$_2$CuO$_4$, (ii) orbital polaron when a hole is added
+to the alternating orbital (AO) ordered plane in LaMnO$_3$, and (iii)
+spin-orbital polaron when a hole is added to the AF and AO ordered plane in
+LaVO$_3$. Comparison of the distinct features of the above polarons can shed
+some light on the basic differences between the experimental phase diagrams of
+the lightly doped transition metal oxides La$_{2-x}$Sr$_x$CuO$_4$,
+La$_{1-x}$Sr$_x$MnO$_3$, and La$_{1-x}$Sr$_{x}$VO$_3$.",0907.0420v1
+2009-07-06,Electrosteric enhanced stability of functional sub-10 nm cerium and iron oxide particles in cell culture medium,"Applications of nanoparticles in biology require that the nanoparticles
+remain stable in solutions containing high concentrations of proteins and
+salts, as well as in cell culture media. In this work, we developed simple
+protocols for the coating of sub-10 nm nanoparticles and evaluated the
+colloidal stability of dispersions in various environments. Ligands (citric
+acid), oligomers (phosphonate-terminated poly(ethylene oxide)) and polymers
+(poly(acrylic acid)) were used as nanometer-thick adlayers for cerium (CeO2)
+and iron (gamma-Fe2O3) oxide nanoparticles. The organic functionalities were
+adsorbed on the particle surfaces via physical (electrostatic) forces.
+Stability assays at high ionic strength and in cell culture media were
+performed by static and dynamic light scattering. Among the three coating
+examined, we found that only poly(acrylic acid) fully preserved the dispersion
+stability on the long term (> weeks). The improved stability was explained by
+the multi-point attachments of the chains onto the particle surface, and by the
+adlayer-mediated electrosteric interactions. These results suggest that
+anionically charged polymers represent an effective alternative to conventional
+coating agents.",0907.1008v1
+2009-07-30,Solvothermal Reduction of Chemically Exfoliated Graphene Sheets,"Graphene has attracted much attention due to its interesting properties and
+potential applications. Chemical exfoliation methods have been developed to
+make graphene recently, aimed at large-scale assembly and applications such as
+composites and Li ion batteries. Although efficient, the chemical exfoliation
+methods involve oxidation of graphene and introduce defects in the as-made
+sheets. Hydrazine reduction at 100 has shown to partially restore the structure
+and conductance of graphite oxide. However, the reduced GO still shows strong
+defect peaks in Raman spectra with higher resistivity than pristine graphene by
+2 to 3 orders of magnitude. It is important to produce much less defective
+graphene sheets than GO, and develop more effective graphene reduction.
+Recently, we reported a mild exfoliation-reintercalation-expansion method to
+form high-quality GS with higher conductivity and lower oxidation degree than
+GO.5 Here, we present a 180 solvothermal reduction method for our GS and GO.
+The solvothermal reduction is more effective than the earlier reduction methods
+in lowering the oxygen and defect levels in GS, increasing the graphene
+domains, and bringing the conductivity of GS close to pristine graphene. The
+reduced GS possess the highest degree of pristinity among chemically derived
+graphene.",0907.5417v1
+2009-08-14,Electrostatically induced phase transitions in superconducting complex oxides,"We describe quantum phase transitions in superconducting complex oxides which
+could be tuned by electrostatic charge transfer. Using a simple model for the
+superconductivity of a thin film or surface of a bulk copper oxide, we show
+that tuning the carrier density may allow the visitation of several
+superconducting phases with different pairing symmetries such as extended $s$-
+$(se)$, $d$- and $(se \pm id)$-wave. We construct a universal phase diagram for
+single-band superconductors with $se$- and d-wave components of the order
+parameter based on symmetry considerations alone. For a specific model with
+nearest neighbor attraction, we obtain the phase diagram in the interaction
+versus filling factor space showing the boundaries of the possible phases.
+Finally, we calculate the superfluid density and penetration depth as
+characteristic properties of each phase.",0908.2011v1
+2009-10-13,Appearance of ferroelectricity in BaO nanowires,"We predict that ferroelectric phase can be induced by the strong intrinsic
+surface stress inevitably present under the curved surface in the high aspect
+ratio cylindrical nanoparticles of nonferroelectric binary oxides (BaO, EuO,
+MgO, etc). We calculated the sizes and temperature range of the ferroelectric
+phase in BaO nanowires. The analytical calculations were performed within
+Landau-Ginzburg-Devonshire theory with phenomenological parameters extracted
+from the first principle calculations [E. Bousquet et al, Strain-induced
+ferroelectricity in simple rocksalt binary oxides. arXiv:0906.4235v1] and
+tabulated experimental data. In accordance with our calculations BaO nanowires
+of radius ~(1-10) nm can be ferroelectric at room temperature (with spontaneous
+polarization values up to 0.5 C/m2) for the typical surface stress coefficients
+~ (10-50) N/m. We hope that our prediction can stimulate both experimental
+studies of rocksalt binary oxides nanoparticles polar properties as well as the
+first principle calculations of their spontaneous dipole moment induced by the
+intrinsic stress under the curved surface.",0910.2421v1
+2010-02-02,Ballistic Conductance in Oxidized Si Nanowires,"The influence of local oxidation in silicon nanowires on hole transport, and
+hence the effect of varying the oxidation state of silicon atoms at the wire
+surface, is studied using density functional theory in conjunction with a
+Green's function scattering method. For silicon nanowires with growth direction
+along [110] and diameters of a few nanometers, it is found that the
+introduction of oxygen bridging and back bonds does not significantly degrade
+hole transport for voltages up to several hundred millivolts relative to the
+valence band edge. As a result, the mean free paths are comparable to or longer
+than the wire lengths envisioned for transistor and other nanoelectronics
+applications. Transport along [100]-oriented nanowires is less favorable, thus
+providing an advantage in terms of hole mobilities for [110] nanowire
+orientations, as preferentially produced in some growth methods.",1002.0430v1
+2010-02-16,Suppression of Octahedral Tilts and Associated Changes of Electronic Properties at Epitaxial Oxide Heterostructure Interfaces,"Epitaxial oxide interfaces with broken translational symmetry have emerged as
+a central paradigm behind the novel behaviors of oxide superlattices. Here, we
+use scanning transmission electron microscopy to demonstrate a direct,
+quantitative unit-cell-by-unit-cell mapping of lattice parameters and oxygen
+octahedral rotations across the BiFeO3-La0.7Sr0.3MnO3 interface to elucidate
+how the change of crystal symmetry is accommodated. Combined with low-loss
+electron energy loss spectroscopy imaging, we demonstrate a mesoscopic
+antiferrodistortive phase transition and elucidate associated changes in
+electronic properties in a thin layer directly adjacent to the interface.",1002.2989v1
+2010-03-09,Femtosecond Pump-Probe Studies of Reduced Graphene Oxide Thin Films,"The dynamics of photocarriers in reduced graphene oxide thin films is studied
+by using ultrafast pump-probe spectroscopy. Time dependent differential
+transmissions are measured with sample temperatures ranging from 9 to 300 K. At
+each sample temperature and probe delay, the sign of differential transmission
+remains positive. A fast energy relaxation of hot carriers is observed, and is
+found to be independent of sample temperature. Our experiments show that the
+carrier dynamics in reduced graphene oxide is similar to other types of
+graphene, and that the differential transmission is caused by phase-state
+filling of carriers.",1003.1972v2
+2010-03-22,Colossal dielectric constants in transition-metal oxides,"Many transition-metal oxides show very large (""colossal"") magnitudes of the
+dielectric constant and thus have immense potential for applications in modern
+microelectronics and for the development of new capacitance-based
+energy-storage devices. In the present work, we thoroughly discuss the
+mechanisms that can lead to colossal values of the dielectric constant,
+especially emphasising effects generated by external and internal interfaces,
+including electronic phase separation. In addition, we provide a detailed
+overview and discussion of the dielectric properties of CaCu3Ti4O12 and related
+systems, which is today's most investigated material with colossal dielectric
+constant. Also a variety of further transition-metal oxides with large
+dielectric constants are treated in detail, among them the system La2-xSrxNiO4
+where electronic phase separation may play a role in the generation of a
+colossal dielectric constant.",1003.4272v1
+2010-06-11,"New Iron Arsenide Oxides (Fe2As2)(Sr4(Sc,Ti)3O8), (Fe2As2)(Ba4Sc3O7.5), and (Fe2As2)(Ba3Sc2O5)","We synthesized new layered iron arsenide oxides
+(Fe2As2)(Sr4(Sc,Ti)3O8),(Fe2As2)(Ba4Sc3O7.5), and (Fe2As2)(Ba3Sc2O5). The
+crystal structures of these compounds are tetragonal with a space group of
+I4/mmm. The structure of (Fe2As2)(Sr4(Sc,Ti)3O8) and (Fe2As2)(Ba4Sc3O7.5)
+consists of the alternate stacking of antifluorite Fe2As2 layers and triple
+perovskite-type oxide layers. The interlayer distance between the Fe planes of
+(Fe2As2)(Ba4Sc3O7.5) is ~18.7 A. Moreover, the a-axis of (Fe2As2)(Ba3Sc2O5) is
+the longest among the layered iron pnictides, indicating the structural
+flexibility of the layered iron pnictide containing perovskite-type layers. The
+bulk sample of (Fe2As2)(Sr4(Sc0.6Ti0.4)3O8) exhibited diamagnetism up to 28 K
+in susceptibility measurements.",1006.2353v1
+2010-07-22,Oxygen-Induced Surface Reconstruction of SrRuO3 and Its Effect on the BaTiO3 Interface,"Atomically engineered oxide multilayers and superlattices display unique
+properties responsive to the electronic and atomic structures of the
+interfaces. We have followed the growth of ferroelectric BaTiO3 on SrRuO3
+electrode with in situ atomic scale analysis of the surface structure at each
+stage. An oxygen-induced surface reconstruction of SrRuO3 leads to formation of
+SrO rows spaced at twice the bulk periodicity. This reconstruction modifies the
+structure of the first BaTiO3 layers grown subsequently, including intermixing
+observed with cross-section spectroscopy. These observations reveal that this
+common oxide interface is much more interesting than previously reported, and
+provide a paradigm for oxygen engineering of oxide structure at an interface.",1007.4006v1
+2010-09-09,First-principles computational study of defect clustering in solid solutions of ThO$_{2}$ with trivalent oxides,"The energetics of mixing and defect ordering in solid solutions of
+fluorite-structured ThO$_{2}$ with oxides of trivalent cations (Sc, In, Y, Nd,
+La) are investigated by electronic density-functional-theory (DFT). Through DFT
+calculations of structures enumerated by lattice-algebra techniques, we
+identify the lowest-energy patterns for defect clustering for four separate
+dopant concentrations. The most stable structures are characterized by a
+repulsive interaction between nearest-neighbor vacancies on the oxygen
+sublattice. The enthalpies of formation with respect to constituent oxides are
+positive for all dopants considered, and show a tendency to decrease in
+magnitude as the size and electronegativity of the trivalent dopant decrease.
+Due to the small positive formation enthalpies and low oxygen-vacancy binding
+energy with La dopants, La$_{2}$O$_{3}$-ThO$_{2}$ solid solutions are predicted
+to have relatively high ionic conductivities relative to those for the other
+aliovalent dopants considered. Our results are compared with those for the more
+widely studied ZrO$_{2}$ and CeO$_{2}$ fluorite-structured solid solutions with
+trivalent cations.",1009.1850v1
+2010-10-19,Reflexion Mössbauer analysis of the in situ oxidation products hydroxycarbonate green rust,"The purpose of this study is to determine the nature of the oxidation
+products of FeII-III hydroxycarbonate FeII4FeIII2(OH)12CO3~3H2O (green rust
+GR(CO32-)) by using the miniaturised M\""ossbauer spectrometer MIMOS II. Two
+M\""ossbauer measurements methods are used: method (i) with green rust pastes
+coated with glycerol and spread into Plexiglas sample holders, and method (ii)
+with green rust pastes in the same sample holders but introduced into a
+gas-tight cell with a beryllium window under a continuous nitrogen flow. Method
+(ii) allows us to follow the continuous deprotonation of GR(CO32-) into the
+fully ferric deprotonated form FeIII6O4(OH)8CO3~3H2O by adding the correct
+amount of H2O2, without any further oxidation or degradation of the samples.",1010.3852v1
+2010-11-17,Oxidation resistance of graphene-coated Cu and Cu/Ni alloy,"The ability to protect refined metals from reactive environments is vital to
+many industrial and academic applications. Current solutions, however,
+typically introduce several negative effects, including increased thickness and
+changes in the metal physical properties. In this paper, we demonstrate for the
+first time the ability of graphene films grown by chemical vapor deposition to
+protect the surface of the metallic growth substrates of Cu and Cu/Ni alloy
+from air oxidation. SEM, Raman spectroscopy, and XPS studies show that the
+metal surface is well protected from oxidation even after heating at 200
+\degree C in air for up to 4 hours. Our work further shows that graphene
+provides effective resistance against hydrogen peroxide. This protection method
+offers significant advantages and can be used on any metal that catalyzes
+graphene growth.",1011.3875v1
+2010-12-24,Correlation between structural defects and optical properties of Cu2O nanowires grown by thermal oxidation,"Cuprous oxide (Cu2O) nanowires were grown by a simple, catalyst-free thermal
+oxidation method starting from a copper foil substrate. Wire growth was
+performed at different conditions by varying oxygen partial pressure and
+heating temperature, and produced structural defects such as stacking faults
+and twin structures of grown nanowires were characterized by transmission
+electron microscopy. A moderate oxygen partial pressure ~5% with a relatively
+high temperature at 500 oC is found to be an optimal condition for growing
+high-quality Cu2O nanowires, while either lowering temperature or enhancing O2
+partial pressure can yield higher density of planar defects. In order to
+further investigate optical properties of grown nanowires, photoluminescence
+measurements were also performed and correlated with structural
+characterization results, indicating that increase of structural defects such
+as stacking faults and twins tended to enhance broad defect-related emissions
+and suppress the exciton emissions near Cu2O band-edge.",1012.5338v2
+2011-02-18,Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi2Se3,"Bi2Se3 is a topological insulator with metallic surface states residing in a
+large bulk bandgap. It is believed that Bi2Se3 gets additional n-type doping
+after exposure to atmosphere, thereby reducing the relative contribution of
+surface states in total conductivity. In this letter, transport measurements on
+Bi2Se3 nanoribbons provide additional evidence of such environmental doping
+process. Systematic surface composition analyses by X-ray photoelectron
+spectroscopy reveal fast formation and continuous growth of native oxide on
+Bi2Se3 under ambient conditions. In addition to n-type doping at the surface,
+such surface oxidation is likely the material origin of the degradation of
+topological surface states. Appropriate surface passivation or encapsulation
+may be required to probe topological surface states of Bi2Se3 by transport
+measurements.",1102.3935v1
+2011-02-21,Uranium oxides investigated by X-ray absorption and emission spectroscopies,"X-ray absorption and resonant X-ray emission measurements at the O 1s edge of
+the uranium oxides UO2, U3O8 and UO3 are presented. The spectral shapes of the
+O K{\alpha} X-ray emission spectra of UO3 exhibit significant excitation energy
+dependence, from an asymmetric to a symmetric form, which differs from those of
+UO2 and U3O8. This energy dependence is attributed to a significant difference
+in the oxygen-uranium hybridization between two different sites in the crystal
+structure of UO3. The spectral shapes of UO2 and U3O8 are also found to be
+different but without significant energy dependence. The experimental spectra
+of the valence and conduction bands of the uranium oxides are compared to the
+results of electronic structure calculations available in the literature.",1102.4242v2
+2011-03-22,Structure and properties of functional oxide thin films: Insights from electronic-structure calculations,"The confluence of state-of-the-art electronic-structure computations and
+modern synthetic materials growth techniques is proving indispensable in the
+search for and discovery of new functionalities in oxide thin films and
+heterostructures. Here, we review the recent contributions of
+electronic-structure calculations to predicting, understanding, and discovering
+new materials physics in thin-film perovskite oxides. We show that such
+calculations can accurately predict both structure and properties in advance of
+film synthesis, thereby guiding the search for materials combinations with
+specific targeted functionalities. In addition, because they can isolate and
+decouple the effects of various parameters which unavoidably occur
+simultaneously in an experiment -- such as epitaxial strain, interfacial
+chemistry and defect profiles -- they are able to provide new fundamental
+knowledge about the underlying physics. We conclude by outlining the
+limitations of current computational techniques, as well as some important open
+questions that we hope will motivate further methodological developments in the
+field.",1103.4418v1
+2011-06-03,Selective tuning of high-Q silicon photonic crystal nanocavities via laser-assisted local oxidation,"We examine the cavity resonance tuning of high-Q silicon photonic crystal
+heterostructures by localized laser-assisted thermal oxidation using a 532 nm
+continuous wave laser focused to a 2.5 mm radius spot-size. The total shift is
+consistent with the parabolic rate law. A tuning range of up to 8.7 nm is
+achieved with ~ 30 mW laser powers. Over this tuning range, the cavity Q
+decreases from 3.2\times10^5 to 1.2\times10^5. Numerical simulations model the
+temperature distributions in the silicon photonic crystal membrane and the
+cavity resonance shift from oxidation.",1106.0705v1
+2011-06-24,Observation of drift and diffusion processes in Ti/TiOx/Ti memristive devices prepared by local anodic oxidation,"We demonstrate that memristive devices can be fabricated by tip-induced
+oxidation of thin metallic films using atomic force microscope. Electrical
+measurements of such prepared Ti/TiOx/Ti test structures confirmed their
+memristive behavior and inferred diffusion of oxygen vacancies in the TiOx
+barrier. Consequent Kelvin probe force microscopy studies provided evidence for
+the diffusion, as well as for expected oxygen vacancy drift. Time evolution of
+the space distribution of the vacancies due to the diffusion process revealed
+minute-scale (at least) retention times of the devices. The work presents
+technology alternative for fabrication of memristive nanodevices in geometry
+favouring advantageous scanning probe microscopy studies of their in-barrier
+processes, as well as widely utilizable approach to search for novel oxide
+materials for perspective memristive applications.",1106.5006v3
+2011-07-12,High Tc superconductivity in superlattices of insulating oxides,"We report the occurrence of superconductivity, with maximum Tc = 40 K, in
+superlattices (SLs) based on two insulating oxides, namely CaCuO2 and SrTiO3.
+In these (CaCuO2)n/(SrTiO3)m SLs, the CuO2 planes belong only to CaCuO2 block,
+which is an antiferromagnetic insulator. Superconductivity, confined within few
+unit cells at the CaCuO2/SrTiO3 interface, shows up only when the SLs are grown
+in a highly oxidizing atmosphere, because of extra oxygen ions entering at the
+interfaces. Evidence is reported that the hole doping of the CuO2 planes is
+obtained by charge transfer from the interface layers, which act as charge
+reservoir.",1107.2239v3
+2011-08-04,Oxides and nitrides as alternative plasmonic materials in the optical range,"As alternatives to conventional metals, new plasmonic materials offer many
+advantages in the rapidly growing fields of plasmonics and metamaterials. These
+advantages include low intrinsic loss, semiconductor-based design,
+compatibility with standard nanofabrication processes, tunability, and others.
+Transparent conducting oxides such as Al:ZnO, Ga:ZnO and indium-tin-oxide (ITO)
+enable many high-performance metamaterial devices operating in the near-IR.
+Transition-metal nitrides such as TiN or ZrN can be substitutes for
+conventional metals in the visible frequencies. In this paper we provide the
+details of fabrication and characterization of these new materials and discuss
+their suitability for a number of metamaterial and plasmonic applications.",1108.0993v1
+2011-08-07,A comparative study of semiconductor-based plasmonic metamaterials,"Recent metamaterial (MM) research faces several problems when using
+metal-based plasmonic components as building blocks for MMs. The use of
+conventional metals for MMs is limited by several factors: metals such as gold
+and silver have high losses in the visible and near-infrared (NIR) ranges and
+very large negative real permittivity values, and in addition, their optical
+properties cannot be tuned. These issues that put severe constraints on the
+device applications of MMs could be overcome if semiconductors are used as
+plasmonic materials instead of metals. Heavily doped, wide bandgap oxide
+semiconductors could exhibit both a small negative real permittivity and
+relatively small losses in the NIR. Heavily doped oxides of zinc and indium
+were already reported to be good, low loss alternatives to metals in the NIR
+range. Here, we consider these transparent conducting oxides (TCOs) as
+alternative plasmonic materials for many specific applications ranging from
+surface-plasmon-polariton waveguides to MMs with hyperbolic dispersion and
+epsilon-near-zero (ENZ) materials. We show that TCOs outperform conventional
+metals for ENZ and other MM-applications in the NIR.",1108.1531v1
+2011-12-19,Transfer-free fabrication of graphene transistors,"We invented a method to fabricate graphene transistors on oxidized silicon
+wafers without the need to transfer graphene layers. To stimulate the growth of
+graphene layers on oxidized silicon a catalyst system of nanometer thin
+aluminum/nickel double layer is used. This catalyst system is structured via
+liftoff before the wafer enters the catalytic chemical vapor deposition (CCVD)
+chamber. In the subsequent methane based growth process monolayer graphene
+field-effect transistors (MoLGFETs) and bilayer graphene transistors (BiLGFETs)
+are realized directly on oxidized silicon substrate, whereby the number of
+stacked graphene layers is determined by the selected CCVD process parameters,
+e.g. temperature and gas mixture. Subsequently, Raman spectroscopy is performed
+within the channel region in between the catalytic areas and the Raman spectra
+of fivelayer, bilayer and monolayer graphene confirm the existence of graphene
+grown by this silicon-compatible, transfer-free and in-situ fabrication
+approach. These graphene FETs will allow a simple and low-cost integration of
+graphene devices for nanoelectronic applications in a hybrid silicon CMOS
+environment.",1112.4320v1
+2011-12-21,Instability of Amorphous Oxide Semiconductors via Carrier-Mediated Structural Transition between Disorder and Peroxide State,"The excited holes occupying the valence band tail states in amorphous oxide
+semiconductors are found to induce formation of meta-stable O$_2^{2-}$ peroxide
+defects. The valence band tail states are at least partly characterized by the
+O-O pp{\sigma}* molecular orbital, and the localized-hole-mediated lattice
+instability results in the formation of the peroxide defects. Along with the
+O-O bond formation, the pp{\sigma}* state is heightened up into the conduction
+bands, and two electrons are accordingly doped in the electronic ground state.
+The energy barrier from the O$_2^{2-}$ peroxide state to the normal disorder
+state is found to be 0.97 eV in hybrid density functional theory. The
+hole-mediated formation of the meta-stable peroxide defects and their
+meta-stability is suggested as an origin of the negative bias and/or
+illumination stress instability in amorphous oxide semiconductors.",1112.4914v1
+2012-03-05,Growth of Oriented Au Nanostructures: Role of Oxide at the Interface,"We report on the formation of oriented gold nano structures on Si(100)
+substrate by annealing procedures in low vacuum (\approx10-2 mbar) and at high
+temperature (\approx 975^{\circ} C). Various thicknesses of gold films have
+been deposited with SiOx (using high vacuum thermal evaporation) and without
+SiOx (using molecular beam epitaxy) at the interface on Si(100). Electron
+microscopy measurements were performed to determine the morphology, orientation
+of the structures and the nature of oxide layer. Interfacial oxide layer, low
+vacuum and high temperature annealing conditions are found to be necessary to
+grow oriented gold structures. These gold structures can be transferred by
+simple scratching method.",1203.0819v1
+2012-06-08,Gate Stack Dielectric Degradation of Rare-Earth Oxides Grown on High Mobility Ge Substrates,"We report on the dielectric degradation of Rare-Earth Oxides (REOs), when
+used as interfacial buffer layers together with HfO2 high-k films (REOs/HfO2)
+on high mobility Ge substrates. Metal-Oxide-Semiconductor (MOS) devices with
+these stacks,show dissimilar charge trapping phenomena under varying levels of
+Constant- Voltage-Stress (CVS) conditions, which also influences the measured
+densities of the interface (Nit) and border (NBT) traps. In the present study
+we also report on C-Vg hysteresis curves related to Nit and NBT. We also
+propose a new model based on Maxwell-Wagner instabilities mechanism that
+explains the dielectric degradations (current decay transient behavior) of the
+gate stack devices grown on high mobility substrates under CVS bias from low to
+higher fields, and which is unlike to those used for other MOS devices.
+Finally, the time dependent degradation of the corresponding devices revealed
+an initial current decay due to relaxation, followed by charge trapping and
+generation of stress-induced leakage which eventually lead to hard breakdown
+after long CVS stressing.",1206.1887v2
+2012-06-12,Effect of Oxygen Adsorption on the Local Properties of Epitaxial Graphene on SiC (0001),"The effect of oxygen adsorption on the local structure and electronic
+properties of monolayer graphene grown on SiC(0001) has been studied by means
+of Low Energy Electron Microscopy (LEEM), microprobe Low Energy Electron
+Diffraction (\muLEED) and microprobe Angle Resolved Photoemission (\muARPES).
+We show that the buffer layer of epitaxial graphene on SiC(0001) is partially
+decoupled after oxidation. The monitoring of the oxidation process demonstrates
+that the oxygen saturates the Si dangling bonds, breaks some Si-C bonds at the
+interface and intercalates the graphene layer. Accurate control over the
+oxidation parameters enables us to tune the charge density modulation in the
+layer.",1206.2474v1
+2012-07-04,Solvent effect on the Thermodynamics of the Oxidation of Potential Antioxidant Garlic Compounds,"Antioxidant capacity of garlic has been attributed to organic sulfur
+compounds such us allyl methyl disulfide. Using quantum chemical calculations
+at B3LYP/6-31+G (d) and G3MP2B3/6-31+G (d) levels of theory, we study three
+possible oxidation reactions of this compound against hydrogen peroxide, a
+reactive oxygen species, from a thermodynamic point of view. Because these
+reactions are supposed to occur in biological media, solvent effect was taken
+into consideration. Oxidation over the double bond that leads to the formation
+of an epoxide is more thermodynamically feasible, limiting the antioxidant
+capacity of this compound.",1207.1092v2
+2012-07-16,Ultrafast carrier phonon dynamics in NaOH-reacted graphite oxide film,"NaOH-reacted graphite oxide film was prepared by decomposing epoxy groups in
+graphite oxide into hydroxyl and -ONa groups with NaOH solution. Ultrafast
+carrier dynamics of the sample were studied by time-resolved transient
+differential reflection (\DeltaR/R). The data show two exponential relaxation
+processes. The slow relaxation process (\sim2ps) is ascribed to low energy
+acoustic phonon mediated scattering. The electron-phonon coupling and
+first-principles calculation results demonstrate that - OH and -ONa groups in
+the sample are strongly coupled. Thus, we attribute the fast relaxation process
+(\sim0.17ps) to the coupling of hydroxyl and -ONa groups in the sample.",1207.3643v1
+2012-08-28,Modulation doping to control the high-density electron gas at a polar/non-polar oxide interface,"A modulation-doping approach to control the carrier density of the
+high-density electron gas at a prototype polar/non-polar oxide interface is
+presented. It is shown that the carrier density of the electron gas at a
+GdTiO3/SrTiO3 interface can be reduced by up to 20% from its maximum value (~
+3x10^14 cm^-2) by alloying the GdTiO3 layer with Sr. The Seebeck coefficient of
+the two-dimensional electron gas increases concurrently with the decrease in
+its carrier density. The experimental results provide insight into the origin
+of charge carriers at oxide interfaces exhibiting a polar discontinuity.",1208.5711v1
+2012-08-30,Spectroscopic fingerprints of valence and spin states in manganese oxides and fluorides,"We performed a systematic study of soft X-ray absorption spectroscopy in
+various manganese oxides and fluorides. Both Mn L-edges and ligand (O and F)
+K-edges are presented and compared with each other. Despite the distinct
+crystal structure and covalent/ionic nature in different systems, the Mn-L
+spectra fingerprint the Mn valence and spin states through spectral lineshape
+and energy position consistently and evidently. The clear O- and F- K pre-edge
+features in our high resolution spectra enable a quantitative definition of the
+molecular orbital diagram with different Mn valence. In addition, while the
+binding energy difference of the O-1s core electrons leads to a small shift of
+the O-K leading edges between trivalent and quadrivalent manganese oxides, a
+significant edge shift, with an order of magnitude larger in energy, was found
+between divalent and trivalent compounds, which is attributed to the spin
+exchange stabilization of half- filled 3d system. This shift is much enhanced
+in the ionic fluoride system. This work provides the spectroscopic foundation
+for further studies of complicated Mn compounds.",1208.6319v2
+2012-09-04,Fractionally delta-doped oxide superlattices for higher carrier mobilities,"A 2D electron gas system in an oxide heterostructure serves as an important
+playground for novel phenomena. Here, we show that, by using fractional
+delta-doping to control the interface's composition in LaxSr1-xTiO3/SrTiO3
+artificial oxide superlattices, the filling-controlled 2D insulator-metal
+transition can be realized. The atomic-scale control of d-electron band
+filling, which in turn contributes to the tuning of effective mass and density
+of the charge carriers, is found to be a fascinating route to substantially
+enhanced carrier mobilities.",1209.0721v1
+2012-09-15,First Principles Modeling of the Initial Stages of Organic Solvent Decomposition on Li(x)Mn(2)O(4) (100) Surfaces,"Density functional theory and ab initio molecular dynamics simulations are
+applied to investigate the initial steps of ethylene carbonate (EC)
+decomposition on spinel Li(0.6)Mn(2)O(4) (100) surfaces. EC is a key component
+of the electrolyte used in lithium ion batteries. We predict an slightly
+exothermic EC bond breaking event on this oxide facet, which facilitates
+subsequent EC oxidation and proton transfer to the oxide surface. Both the
+proton and the partially decomposed EC fragment weaken the Mn-O ionic bonding
+network. Implications for interfacial film made of decomposed electrolyte on
+cathode surfaces, and Li(x)Mn(2)O(4) dissolution during power cycling, are
+discussed.",1209.3428v1
+2012-09-19,Thulium and ytterbium-doped titanium oxide thin films deposited by ultrasonic spray pyrolysis,"Thin films of thulium and ytterbium-doped titanium oxide were grown by
+metal-organic spray pyrolysis deposition from titanium(IV)oxide
+bis(acetylacetonate), thulium(III) tris(2,2,6,6-tetramethyl-3,5-heptanedionate)
+and ytterbium(III) tris(acetylacetonate). Deposition temperatures have been
+investigated from 300{\deg}C to 600{\deg}C. Films have been studied regarding
+their crystallity and doping quality. Structural and composition
+characterisations of TiO2:Tm,Yb were performed by electron microprobe, X-ray
+diffraction and Fourier transform infrared spectroscopy. The deposition rate
+can reach 0.8 \mum/h. The anatase phase of TiO2 was obtained after synthesis at
+400{\deg}C or higher. Organic contamination at low deposition temperature is
+eliminated by annealing treatments.",1209.4226v1
+2012-09-20,Nucleating Acicular Ferrite with Galaxite (Al2O3MnO) and Manganese Oxide (MnO2) in FeMnAlC steels,"Effectiveness of galaxite (Al2O3MnO) and manganese oxide (MnO2) in nucleating
+acicular ferrite was demonstrated in a steel with composition of
+Fe-13.92Mn-4.53Al-1.28Si-0.11C. The hot rolled and quenched steel had a duplex
+microstructure of delta-ferrite and partially transformed austenite. Thermal
+treatments were used to manipulate the concentration and type of oxides and the
+ferrite plate density was found to correlate with inclusions of low misfit.
+Both bainitic and acicular ferrite were observed and the prior austenite had a
+grain diameter of 16.5 micrometers. Upon tensile testing the retained austenite
+transformed to alpha-martensite. Ultimate tensile strength and elongation were
+970 MPa and 40 percent. The yield strength was found to be dependent on the
+ferrite plate size, which varied linearly with the strength of the austenite.
+Ductility decreased as the strength disparity between delta-ferrite and
+deformation-induced alpha-martensite increased.",1209.4546v1
+2012-09-28,The formation of Er-oxide nanoclusters in SiO$_2$ thin films with excess Si,"The nucleation, distribution and composition of erbium embedded in a
+SiO$_2$-Si layer were studied with High Resolution Transmission Electron
+Microscopy (HRTEM), Electron Energy Loss Spectroscopy (EELS), Energy Filtered
+TEM (EFTEM), Scanning Transmission Electron Microscopy (STEM) and X-ray
+Photoelectron Spectroscopy (XPS). When the SiO$_2$ layer contains small amounts
+of Si and Er, nanoclusters of Er-oxide are formed throughout the whole layer.
+Exposure of the oxide to an electron beam with 1.56*10$^6$
+electrons/nm$^2$/sec. causes nanocluster growth. Initially this growth matches
+the Ostwald ripening model, but eventually it stagnates at a constant
+nanocluster radius of 2.39 nm.",1210.0016v1
+2012-10-20,One-way Tamm plasmon-polaritons on the interface of magnetophotonic crystals and conducting metal oxides,"We demonstrate theoretically the existence of one-way Tamm plasmon-polaritons
+on the interface between magnetophotonic crystals and conducting metal oxides.
+In contrast to conventional surface plasmon-polaritons (SPPs), Tamm
+plasmon-polariton (TPPs) occur at frequencies above the bulk plasma frequency
+of the conducting materials, provided that the dispersion curves of such
+surface modes lie outside the light cone for the conducting oxides and
+simultaneously fall into the photonic band gap of the magnetophotonic crystal.
+The nonreciprocal properties of TPPs are caused by violation of the periodicity
+and time reversal symmetry in the structure. Calculations on the field
+distribution and transmission spectra through the structure are employed to
+confirm the theoretical results, which could potentially impact on a broad
+range of SPP-related phenomena in applications.",1210.5668v1
+2012-11-27,Two Dimensional Polymerization of Graphene Oxide: Bottom-up Approach,"We demonstrate a bottom-up synthesis of structures similar to graphene oxide
+via a two dimensional polymerization. Experimental evidence and discussion are
+conveyed as well as a general framework for this two dimensional
+polymerization. The proposed morphologies and lattice structures of these
+graphene oxides are derived from aldol condensation of alternating three
+nucleophilic and three electrophilic centers of benzenetriol.",1211.6259v2
+2012-12-17,Topological Crystalline Insulators in Transition Metal Oxides,"Topological crystalline insulators (TCI) possess electronic states protected
+by crystal symmetries, rather than time-reversal symmetry. We show that the
+transition metal oxides with heavy transition metals are able to support
+nontrivial band topology resulting from mirror symmetry of the lattice. As an
+example, we consider pyrochlore oxides of the form A$_2$M$_2$O$_7$. As a
+function of spin-orbit coupling strength, we find two $Z_2$ topological
+insulator phases can be distinguished from each other by their mirror Chern
+numbers, each of which indicates a different TCI. We also derive an effective
+$\bf{k\cdot p}$ Hamiltonian, similar to the model introduced for
+$\mathrm{Pb_{1-x}Sn_{x}Te}$, and discuss the effect of an on-site Hubbard
+interaction on the topological crystalline insulator phase using slave-rotor
+mean-field theory, which predicts new classes of topological quantum spin
+liquids.",1212.4162v2
+2012-12-19,Chemical Capping Synthesis of Nickel Oxide Nanoparticles and their Characterizations Studies,"This work reports aspect related to chemical capping synthesis of nano-sized
+particles of nickel oxide. It is a simple, novel and cost effective method. The
+average particle size, specific surface area, crystallinity index are estimated
+from XRD analysis. The structural, functional groups and optical characters are
+analyzed with using of SEM, FTIR and UV- visible techniques. XRD studies
+confirm the presence of high degree of crystallinity nature of nickel oxide
+nanoparticles. Their particle size is found to be 12 nm and specific surface
+area (SSA) is 74m2 g-1. The optical band gap energy value 3.83ev has also been
+determined from UV-vis spectrum.",1212.4595v1
+2013-01-03,Oxide Heterostructures for Efficient Solar Cells,"We propose an unexplored class of absorbing materials for high-efficiency
+solar cells: heterostructures of transition-metal oxides. In particular, LaVO_3
+grown on SrTiO_3 has a direct band gap ~1.1 eV in the optimal range as well as
+an internal potential gradient, which can greatly help to separate the
+photo-generated electron-hole pairs. Furthermore, oxide heterostructures afford
+the flexibility to combine LaVO_3 with other materials such as LaFeO_3 in order
+to achieve even higher efficiencies with band-gap graded solar cells. We use
+density-functional theory to demonstrate these features.",1301.1314v3
+2013-01-08,Pre-Stressed Sub-Surface Contribution on Bulk Diffusion in Metallic Solids,"Our recent modelling works and corresponding numerical simulations realized
+to describe the UO2 oxidation processes confirm the theory showing that an
+applied mechanical strain can strongly affect the local oxygen diffusion in a
+stressed solid. This result allows us to assume that stress field, previously
+applied at the surface of a metallic sample on several microns, will delay the
+degradation during its oxidation. Considering this hypothesis, we implemented a
+FEM simulation code developed in our laboratory to numerically investigate some
+different stress fields applied on a sample sub-surface, that might
+significantly modify the volume diffusion of oxygen during the oxidation
+process. The results of our simulations are presented and discussed from the
+perspective to study the consequences of a surface mechanical treatment on the
+durability of a metallic material.",1301.1619v2
+2013-01-10,Influence of the U3O7 domain structure on cracking during the oxidation of UO2,"Cracking is observed when a UO_{2} single crystal is oxidised in air.
+Previous studies led to the hypothesis that cracking occurs once a critical
+depth of U_{3}O_{7} oxidised layer is reached. We present some \mu-Laue X-ray
+diffraction results, which evidence that the U_{3}O_{7} layer, grown by
+topotaxy on UO_{2}, is made of domains with different crystalline orientations.
+This observation was used to perform a modelling of oxidation coupling chemical
+and mechanical parameters, which showed that the domain patterning induces
+stress localisation. This result is discussed in comparison with stress
+localisation observed in thin layer deposited on a substrate and used to
+propose an interpretation of UO_{2} oxidation and cracking.",1301.2072v1
+2013-01-13,Direct k-space mapping of the electronic structure in an oxide-oxide interface,"The interface between LaAlO3 and SrTiO3 hosts a two-dimensional electron
+system of itinerant carriers, although both oxides are band insulators.
+Interface ferromagnetism coexisting with superconductivity has been found and
+attributed to local moments. Experimentally, it has been established that Ti 3d
+electrons are confined to the interface. Using soft x-ray angle-resolved
+resonant photoelectron spectroscopy we have directly mapped the interface
+states in k-space. Our data demonstrate a charge dichotomy. A mobile fraction
+contributes to Fermi surface sheets, whereas a localized portion at higher
+binding energies is tentatively attributed to electrons trapped by O-vacancies
+in the SrTiO3. While photovoltage effects in the polar LaAlO3 layers cannot be
+excluded, the apparent absence of surface-related Fermi surface sheets could
+also be fully reconciled in a recently proposed electronic reconstruction
+picture where the built-in potential in the LaAlO3 is compensated by surface
+O-vacancies serving also as charge reservoir.",1301.2824v2
+2013-01-21,Variable resistor made by repeated steps of epitaxial deposition and lithographic structuring of oxide layers by using wet chemical etchants,"Variable resistors were constructed from epitaxial SrRuO3 (SRO),
+La0.67Sr0.33MnO3 (LSMO) and SrTiO3 layers with perovskite crystal structure.
+Each layer was patterned separately by lithographic methods. Optimized wet
+chemical etchants and several polishing steps in organic solvents allowed good
+epitaxy of subsequent layers, comparable to epitaxy on pristine substrates.
+Periodate as the oxidizing agent for SRO and iodide with ascorbic acid as the
+reducing agents for LSMO were used to attack these chemically resistant oxides.
+The final devices changed their conductance in a similar manner to previously
+described variable resistors that were defined with shadow masks.",1301.4828v1
+2013-02-04,Efficient Estimation of Band Gaps in Transition-Metal Oxides and Chalcogenides using Density Functional Theory,"The performance of two modern density-functionals, HSE06 and TB-mBJ, on
+predicting electronic structures of metal oxides, chalcogenides and nitrides,
+is studied in terms of band gaps, band structure and projected
+density-of-states. Contrary to GGA, hybrid functionals and GGA+U, both new
+functionals are able to predict band gaps with an appreciable accuracy of 25%
+and thus allow the screening of various classes of (mixed) metal oxides at
+modest computational cost. The calculated electronic structures are largely
+unaffected by the choice of basis functions and software implementation.",1302.0733v3
+2013-02-18,Hot electron transport in a strongly correlated transition metal oxide,"Oxide heterointerfaces are ideal for investigating strong correlation effects
+to electron transport, relevant for oxide-electronics. Using hot-electrons, we
+probe electron transport perpendicular to the La$_{0.7}$Sr$_{0.3}$MnO$_{3}$
+(LSMO)- Nb-doped SrTiO$_3$ (Nb:STO) interface and find the characteristic
+hot-electron attenuation length in LSMO to be 1.48 $\pm$ 0.10 unit cells (u.c.)
+at -1.9 V, increasing to 2.02 $\pm$ 0.16 u.c. at -1.3 V at room temperature.
+Theoretical analysis of this energy dispersion reveals the dominance of
+electron-electron and polaron scattering. Direct visualization of the local
+electron transport shows different transmission at the terraces and at the
+step-edges.",1302.4177v1
+2013-02-18,Effect of Ambient Gas Pressure on the Thermal Exfoliation of Graphite Oxide: Tuning the Number of Graphene Sheets,"We have investigated the effect of ambient gas pressure (Argon) used during
+thermal exfoliation of graphite oxide on the number of graphene sheets in the
+resulting graphene. The ambience gas Ar pressures used are 80, 25, 1 atmosphere
+and 10-3 as well as 10-5 torr. We have found curious result that the number of
+graphene sheets in exfoliated graphene stack is dependent on the applied
+pressure for exfoliation of graphite oxide (GO). By lowering the exfoliation
+pressure, the numbers of sheets get reduced. The numbers of sheets in
+exfoliated graphene stack have been determined by Lorentzian fit of their
+respective 002 peak of XRD profile. The numbers of sheets have also been
+confirmed with high resolution transmission electron microscopy (HRTEM). The
+numbers of sheets in exfoliated graphene stack samples have been found to be
+28, 12, 8, 5 and 3 at 80 atm, 25 atm, 1 atm, 10-3 torr and 10-5 torr pressures
+respectively. The results of present investigation suggest a simple but
+effective method for synthesizing graphene with a specific number of sheets.",1302.4220v1
+2013-02-21,Probing hot electron transport across an epitaxial Schottky interface of SrRuO3/Nb:SrTiO3,"SrRuO3 (SRO), a conducting transition metal oxide, is commonly used for
+engineering domains in BiFeO3. New oxide devices can be envisioned by
+integrating SRO with an oxide semiconductor as Nb doped SrTiO3 (Nb:STO). Using
+a three-terminal device configuration, we study vertical transport in a
+SRO/Nb:STO device at the nanoscale and find local differences in transport,
+that originate due to the high selectivity of SRO growth on the underlying
+surface terminations in Nb:STO. This causes a change in the interface energy
+band characteristics and is explained by the differences in the spatial
+distribution of the interface-dipoles at the local Schottky interface.",1302.5360v1
+2013-03-13,A Ni-Fe Layered Double Hydroxide-Carbon Nanotube Complex for Water Oxidation,"Highly active, durable and cost-effective electrocatalysts for water
+oxidation to evolve oxygen gas hold a key to a range of renewable energy
+solutions including water splitting and rechargeable metal-air batteries. Here,
+we report the synthesis of ultrathin nickel iron layered double hydroxide
+nanoplates on mildly oxidized multi-walled carbon nanotubes. Incorporation of
+Fe into the nickel hydroxide induced the formation of NiFe-layered double
+hydroxide. The nanoplates were covalently attached to a network of nanotubes,
+affording excellent electrical wiring to the nanoplates. The ultra-thin Ni-Fe
+layered double hydroxide nanoplates/carbon nanotube complex was found to
+exhibit unusually high electro-catalytic activity and stability for oxygen
+evolution and outperformed commercial precious metal Ir catalysts.",1303.3308v2
+2013-05-22,Concentration of Vacancies at Metal Oxide Surfaces: Case Study of MgO (100),"We investigate effects of doping on formation energy and concentration of
+oxygen vacancies at a metal oxide surface, using MgO (100) as an example. Our
+approach employs density-functional theory, where the performance of the
+exchange-correlation functional is carefully analyzed, and the functional is
+chosen according to a fundamental condition on DFT ionization energies. The
+approach is further validated by CCSD(T) calculations for embedded clusters. We
+demonstrate that the concentration of oxygen vacancies at a doped oxide surface
+is largely determined by formation of a macroscopically extended space charge
+region.",1305.5157v2
+2013-07-03,Enhanced Hot-Carrier Luminescence in Multilayer Reduced Graphene Oxide Nanospheres,"We report a method to promote photoluminescence emission in graphene
+materials by enhancing carrier scattering instead of directly modifying band
+structure in multilayer reduced graphene oxide (rGO) nanospheres. We
+intentionally curl graphene layers to form nanospheres by reducing graphene
+oxide with spherical polymer templates to manipulate the carrier scattering.
+These nanospheres produce hot-carrier luminescence with more than ten-fold
+improvement of emission efficiency as compared to planar nanosheets. With
+increasing excitation power, hot-carrier luminescence from nanospheres exhibits
+abnormal spectral redshift with dynamic feature associated to the strengthened
+electron-phonon coupling. These experimental results can be well understood by
+considering the screened Coulomb interactions. With increasing carrier density,
+the reduced screening effect promotes carrier scattering which enhances
+hot-carrier emission from such multilayer rGO nanospheres. This
+carrier-scattering scenario is further confirmed by pump-probe measurements.",1307.0940v1
+2013-07-23,Solution calorimetry investigations of new phase BaCe0.6Y0.3In0.1O2.8,"The preparation of BaCeO3 doped by yttrium and indium oxides
+(BaCe0.6Y0.3In0.1O2.8) has been performed by solid-state reaction from BaCO3,
+CeO2, Y2O3, In2O3. The compound BaCe0.6Y0.3In0.1O2.8 has been synthesized for
+the first time. The X-ray measurements have showed that BaCe0.6Y0.3In0.1O2.8
+has an orthorhombic structure (space group Pmcn). The standard formation
+enthalpies of BaCe0.6Y0.3In0.1O2.8 have been determined by solution calorimetry
+combining the solution enthalpies of BaCe0.6Y0.3In0.1O2.8 and BaCl2 + 0.6CeCl3
++ 0.3YCl3 + 0.1InCl3 mixtures in 1 M HCl with 0.1 M KI at 298.15 K and
+literature data. It has been obtained that above-mentioned mixed oxide is
+thermodynamically stable with respect to their decomposition into binary oxides
+at room temperatures. It has been also shown that BaCe0.6Y0.3In0.1O2.8 has been
+more thermodynamically favored than BaCe0.9In0.1O2.95.",1307.5940v1
+2013-10-03,Orienting oxygen vacancies for fast catalytic reaction,"Catalysis is indispensable to chemical processes and relevant to many aspects
+of modern life. Owing to the intriguing electronic structures and good ionic
+properties, multivalent transition metal oxides have attracted attention as key
+catalysts for various energy and environmental applications. Here, we
+demonstrate that brownmillerite strontium cobaltite (SrCoO2.5) can be a good
+cathode material for sold oxide fuel cells and rechargeable batteries due to
+the open oxygen frameworks. When the orientation of oxygen vacancy channels
+(OVCs) is properly controlled, one can drastically increase the surface oxygen
+exchange rate approximately up to two orders of magnitude. The improved oxygen
+reduction kinetics is attributed to a substantial decrease in the thermal
+activation energy. Importantly, the strong enhancement of crystallographic
+orientation-dependent oxygen reduction reaction required the creation of
+neither structural disorders nor chemical doping. Thus, our epitaxial approach
+can pave a novel pathway to providing precise interpretation of oxygen
+reduction reactions and to developing oxide-based energy materials.",1310.0984v1
+2013-10-08,Mechanism for Radiation Damage Resistance in Yttrium Oxide Dispersion Strengthened Steels,"ODS steels based on yttrium oxide have been suggested as potential fusion
+reactor wall materials due to their observed radiation resistance properties.
+Presumably this radiation resistance can be related to the interaction of the
+particle with vacancies,self-interstitial atoms (SIAs) and other radiation
+damage debris. Density functional theory has been used to investigate this at
+the atomic scale. Four distinct interfaces, some based on HRTEM observations,
+between iron and yttrium oxide were investigated. It is been shown that the
+Y$_2$O$_3$-Fe interface acts as a strong trap with long-range attraction for
+both interstitial and vacancy defects, allowing recombination without altering
+the interface structure. The catalytic elimination of defects without change to
+the microstructure explains the improved behaviour of ODS steels with respect
+to radiation creep and swelling.",1310.2061v1
+2013-11-10,Geometric Ferroelectricity in Fluoro-Perovskites,"We used first-principles calculations to investigate the existence and origin
+of the ferroelectric in- stability in the ABF3 fluoro-perovskites. We find that
+many fluoro-perovskites have a ferroelectric instability in their high symmetry
+cubic structure, which is of similar amplitude to that commonly found in oxide
+perovskites. In contrast to the oxides, however, the fluorides have nominal
+Born effective charges, indicating a different mechanism for the instability.
+We show that the instability originates from ionic size effects, and is
+therefore in most cases largely insensitive to pressure and strain, again in
+contrast to the oxide perovskites. An exception is NaMnF3, where coherent
+epitaxial strain matching to a substrate with equal in-plane lattice constants
+destabilizes the bulk Pnma structure leading to a ferroelectric, and indeed
+multiferroic, ground state with an unusual polarization/strain response.",1311.2244v1
+2013-12-23,Shape Resonances in superconducting gaps in a 2DEG at oxide-oxide interface,"In multiband superconductivity, the case where the single electron hopping
+between different Fermi surface spots of different symmetry is forbidden by
+selection rules is recently attracting a large interest. The focus is addressed
+to superconductivity made of multiple condensates with different symmetry where
+the chemical potential crosses a 2.5 Lifshitz transition. This can now be
+investigated experimentally by fine-tuning of the chemical potential in the
+range of tens meV around a band edge using gate voltage control. We discuss
+here the case of the two-dimensional electron gas (2DEG), at the interface
+between two insulating oxides confined within a slab of 5 nanometers thickness,
+where the electronic structure is made of subbands generated by quantum size
+effects. We focus on the case of the BCS-BEC transition in the upper subband
+for different pairing strength in the shallow Fermi surface.",1312.6669v2
+2014-01-07,"Wavelength Spacing Tunable, Multiwavelength Q-Switched Mode-Locked Laser Based on Graphene-Oxide-Deposited Tapered Fiber","A wavelength spacing tunable, multiwavelength Q-switched mode-locked (QML)
+fiber laser in an erbium-doped fiber cavity based on graphene oxide deposited
+on tapered fiber is proposed by choosing the diameter and length of the taper,
+graphene oxide thickness and cavity dispersion, in which the wavelength spacing
+could be tuned by pump power. The evolutions of temporal and spectral with
+different pump strengths are investigated. Results show that the tunability of
+the multiwavelength laser can be interpreted by the bound states of QML laser
+resulting from a mutual interaction of dispersion, nonlinear effect, insertion
+loss, and pump power. To the best of our knowledge, it is the first
+experimental observation of bound states of QML, which provides a new mechanism
+to fabricate tunable multiwavelength laser.",1401.1299v1
+2014-01-16,Separating electric field and thermal effects across the metal-insulator transition in vanadium oxide nanobeams,"We present results from an experimental study of the equilibrium and
+non-equilibrium transport properties of vanadium oxide nanobeams near the
+metal-insulator transition (MIT). Application of a large electric field in the
+insulating phase across the nanobeams produces an abrupt MIT and the individual
+roles of thermal and non-thermal effects in driving the transition are studied.
+Transport measurements at temperatures ($T$) far below the critical temperature
+($T_c$) of MIT, in several nanoscale vanadium oxide devices, show that both $T$
+and electric field play distinctly separate, but critical roles in inducing the
+MIT. Specifically, at $T << T_c$ electric field dominates the MIT through an
+avalanche-type process, whereas thermal effects become progressively critical
+as $T$ approaches $T_c$.",1401.4129v1
+2014-01-17,A Carbon Corrosion Model to Evaluate the Effect of Steady State and Transient Operation of a Polymer Electrolyte Membrane Fuel Cell,"A carbon corrosion model is developed based on the formation of surface
+oxides on carbon and platinum of the polymer electrolyte membrane fuel cell
+electrode. The model predicts the rate of carbon corrosion under potential hold
+and potential cycling conditions. The model includes the interaction of carbon
+surface oxides with transient species like OH radicals to explain observed
+carbon corrosion trends under normal PEM fuel cell operating conditions. The
+model prediction agrees qualitatively with the experimental data supporting the
+hypothesis that the interplay of surface oxide formation on carbon and platinum
+is the primary driver of carbon corrosion.",1401.4285v1
+2014-01-18,Formation of a Buffer Layer for Graphene on C-face SiC{0001},"Graphene films prepared by heating the SiC(000-1) surface (the C-face of the
+{0001} surfaces) in a Si-rich environment are studied using low-energy electron
+diffraction (LEED) and low-energy electron microscopy (LEEM). Upon
+graphitization, an interface with rt(43) x rt(43)-R7.6 degree symmetry is
+observed by in situ LEED. After oxidation, the interface displays rt(3) x
+rt(3)-R30 degree symmetry. Electron reflectivity measurements indicate that
+these interface structures arise from a graphene-like ""buffer layer"" that forms
+between the graphene and the SiC, similar to that observed on Si-face SiC. From
+a dynamical LEED structure calculation for the oxidized C-face surface, it is
+found to consist of a graphene layer sitting on top of a silicate (Si2O3)
+layer, with the silicate layer having the well-known structure as previously
+studied on bare SiC(000-1) surfaces. Based on this result, the structure of the
+interface prior to oxidation is discussed.",1401.4552v1
+2014-01-24,Photo-oxidative tuning of individual and coupled GaAs photonic crystal cavities,"We demonstrate a new photo-induced oxidation technique for tuning GaAs
+photonic crystal cavities using a $390~\mathrm{nm}$ pulsed laser with an
+average power of $10~\mathrm{\mu W}$. The laser oxidizes a small $\left(\sim
+500~\mathrm{nm}\right)$ diameter spot, reducing the local index of refraction
+and blueshifting the cavity. The tuning progress can be actively monitored in
+real time. We also demonstrate tuning an individual cavity within a pair of
+proximity-coupled cavities, showing that this method can be used to correct
+undesired frequency shifts caused by fabrication imperfections in cavity
+arrays.",1401.6241v3
+2014-01-31,Alleviating polarity-conflict at the heterointerfaces of KTaO$_3$/GdScO$_3$ polar complex-oxides,"We have synthesized and investigated the heterointerfaces of KTaO$_3$ (KTO)
+and GdScO$_3$ (GSO), which are both polar complex-oxides along the pseudo-cubic
+[001] direction. Since their layers have the same, conflicting net charges at
+interfaces, i.e. KO(-1)/ScO$_2$(-1) or TaO$_2$(+1)/GdO(+1), forming the
+heterointerface of KTO/GSO should be forbidden due to strong Coulomb repulsion,
+the so-called $\textit{polarity conflict}$. However, we have discovered that
+atomic reconstruction occurs at the heterointerfaces between KTO thin-films and
+GSO substrates, which effectively alleviates the polarity conflict without
+destroying the hetero-epitaxy. Our result demonstrates one of the important
+ways to create artificial heterostructures from polar complex-oxides.",1401.8225v2
+2014-02-05,Understanding water permeation in graphene oxide membranes,"Water transport through graphene-derived membranes has gained much interest
+recently due to its promising potential in filtration and separation
+applications. In this work, we explore water permeation in graphene oxide
+membranes using atomistic simulations, by considering flow through interlayer
+gallery, expanded pores such as wrinkles of interedge spaces, and pores within
+the sheet. We find that although flow enhancement can be established by
+nanoconfinement, fast water transport through pristine graphene channels is
+prohibited by a prominent side-pinning effect from capillaries formed between
+oxidized regions. We then discuss flow enhancement in situations according to
+several recent experiments. These understandings are finally integrated into a
+complete picture to understand water permeation through the layer-by-layer and
+porous microstructure and could guide rational design of functional membranes
+for energy and environmental applications.",1402.1014v1
+2014-02-13,New insights on the thermal decomposition of lanthanide(III) and actinide(III) oxalates: from neodymium and cerium to plutonium,"Lanthanides are often used as surrogates to study the properties of actinide
+compounds. Their behaviour is considered to be quite similar as they both
+possess f valence electrons and are close in size and chemical properties. This
+study examines the potential of using two lanthanides (neodymium and cerium) as
+surrogates for plutonium during the thermal decomposition of isomorphic oxalate
+compounds, in the trivalent oxidation state, into oxides. Thus, the thermal
+decomposition of neodymium, cerium and plutonium (III) oxalates are
+investigated by several coupled thermal analyses (TG-DTA/DSC-MS/FT-IR) and
+complementary characterisation techniques (XRD, UV-vis, FT-IR, SEM, carbon
+analyser) under both oxidizing and inert atmosphere. The thermal decomposition
+mechanisms determined in this study confirmed some previous results reported in
+the literature, among diverging propositions, while also elucidating some
+original mechanisms not previously considered. Calculated thermodynamic and
+kinetic parameters for the studied systems under both atmospheres are reported
+and compared with available literature data. Similarities and differences
+between the thermal behaviour of plutonium(III) and lanthanide(III) oxalates
+are outlined.",1402.3046v1
+2014-04-18,Systematic control of carrier concentration and resisitivity in RF sputtered Zinc oxide thin films,"RF sputtered ZnO and Al:ZnO films are attractive transparent conductive
+oxides for fabrication of opto-electronic devices. In this paper we present
+efforts to control carrier concentration and mobility of ZnO/Al:ZnO thin films
+by controlling deposition parameters (RF power, pressure and substrate
+temperature. Al:ZnO thin film with resistivity as low as $\rho$ = $3.8\times
+10^{-4}$ $\Omega$.cm at deposition temperature of 250{\deg}C has been achieved.
+Zinc oxide thin film with low resistivity of $\rho$ = $3.7\times 10^{-2}$
+$\Omega$.cm and high electron mobility of $30$ $\mathrm{cm^{-2}V^{-1}s^{-1}}$
+at deposition temperature of 250{\deg}C with acceptable electronic parameters
+stability has been obtained.Light transmission of Al:ZnO and ZnO samples
+deposited on glass at different substrate temperature has been studied.
+Investigation were made to assess the effect of deposition temperature on the
+photoluminescence spectra (PL) of ZnO/Al:ZnO sputtered on silicon and glass
+substrate. The evolution of near band edge (NBE) and deep level emission (DLE)
+photoluminescence peaks with deposition temperature in ZnO/Al:ZnO sputtered on
+Silicon and glass substrate have been studied.",1404.4902v1
+2014-08-05,Patterning and tuning of electrical and optical properties of graphene by laser induced two-photon oxidation,"Graphene, being an ultrathin, durable, flexible, transparent material with
+superior conductivity and unusual optical properties, promises many novel
+applications in electronics, photonics and optoelectronics. For applications in
+electronics, patterning and modification of electrical properties is very
+desirable since pristine graphene has no band gap. Here we demonstrate a simple
+all-optical patterning method for graphene, based on laser induced two-photon
+oxidation. By tuning the intensity of irradiation and the number of pulses the
+level of oxidation can be controlled to high precision and, therefore, a band
+gap can be introduced and electrical and optical properties can be continuously
+tuned. Arbitrary complex patterning can be performed for air-suspended
+monolayer graphene or for graphene on substrates. The method works at room
+temperature in ambient air and no additional processing step is needed. The
+presented concept allows development of all-graphene electronic and
+optoelectronic devices and complex circuits with an all-optical method.",1408.0905v1
+2014-08-27,Tunable Band gap of Iron-Doped Lanthanum-Modified Bismuth Titanate Synthesized by the Thermal Decomposition of a Secondary Phase,"The photoelectric properties of complex oxides have prompted interest in
+materials with a tunable band gap, because the absorption The substitution of
+iron atoms in La-modified bismuth titanate (BLT) can lead to dramatic
+improvements in the band gap, however, the substitution of iron atoms in BLT
+without forming a BiFeO3 secondary phase is quite challenging. Therefore, a
+series of Fe-doped BLT (Fe-BLT) samples were characterized using a solid
+reaction at various calcination temperatures (300~900{\deg}C) to remove the
+secondary phase. The structural and optical properties were analyzed by X-ray
+diffraction and ultraviolet-visible absorption spectroscopy. This paper reports
+a new route to synthesize a pure Fe-BLT phase with a reduced optical band gap
+by high temperature calcination due to the thermal decomposition of BiFeO3
+during high temperature calcination. This simple route to reduce the second
+phase can be adapted to other complex oxides for use in emerging oxide
+optoelectronic devices.",1408.6294v1
+2014-09-08,Prediction of pressure-induced stabilization of noble-gas-atom compounds with alkali oxides and alkali sulfides,"The cubic antifluorite structure comprises a face-centered cubic sublattice
+of anions with cations on the tetrahedral sites. The voids in the antifluorite
+structure that are crucial for superionicity in Li2O might also act as atomic
+traps. Trapping of guest atoms and small molecules within voids of a host
+structure leads to the formation of what are known as clathrate compounds. Here
+we investigate the possibility of trapping helium or larger neon guest atoms
+under pressure within alkali metal oxide and sulfide structures. We find stable
+helium and neon-bearing compounds at very low pressures. These structures are
+stabilized by a reduction in volume from incorporation of helium or neon atoms
+within the antifluorite structure. We predict that NeCs2S could be stable at
+ambient pressure. Our study suggests a novel class of alkali oxide and sulfide
+materials incorporating noble gas atoms that might potentially be useful for
+gas storage.",1409.2227v2
+2014-09-10,Electronic reconstruction at the interface between band insulating oxides: the LaAlO3/SrTiO3 system,"The conducting quasi-two dimensional electron system (q2DES) formed at the
+interface between LaAlO3 and SrTiO3 band insulators is confronting the
+condensed matter physics community with new paradigms. While the mechanism for
+the formation of the q2DES is debated, new conducting interfaces have been
+discovered paving the way to possible applications in electronics, spintronics
+and optoelectronics. This chapter is an overview of the research on the LAO/STO
+sys-tem, presenting some of the most important results obtained in the last
+decade to clarify the mechanism of formation of the q2DES at the oxide
+interfaces and its peculiar electronic properties as compared to semiconducting
+2D-electron gas.",1409.3098v1
+2014-09-15,Direct observation of charge mediated lattice distortions in complex oxide solid solutions,"Material properties depend sensitively on picometer scale atomic
+displacements introduced by local chemical fluctuations. Direct real-space,
+high spatial-resolution measurements of this compositional variation and
+corresponding distortion can provide new insights into materials behavior at
+the atomic scale. Using aberration corrected scanning transmission electron
+microscopy combined with advanced imaging methods, we observed atom column
+specific, picometer-scale displacements induced by local chemistry in a complex
+oxide solid solution. Displacements predicted from density functional theory
+were found to correlate with the observed experimental trends. Further analysis
+of bonding and charge distribution were used to clarify the mechanisms
+responsible for the detected structural behavior. By extending the experimental
+electron microscopy measurements to previously inaccessible length scales, we
+identified correlated atomic displacements linked to bond differences within
+the complex oxide structure.",1409.4432v1
+2014-09-23,Fabrication of Flexible Super Capacitor Using Laser Lightscribe Technique,"Super capacitors are promising energy storage devices due to their capability
+of delivering high peak current and storing high amount of energy in a short
+time with very low internal power loss. We fabricated the graphene or graphite
+oxide super-capacitor using laser Lightscribe technique. We prepared graphite
+oxide by modified hummers method and used PET film as a flexible substrate on
+which graphite oxide (GO) was coated. Using Lightscribe drive and software, the
+super-capacitor configuration was patterned on the GO coated PET film. During
+the writing process, the laser converts GO into graphene. We characterized the
+fabricated flexible super-capacitor which exhibits high resistance of 20KOhm
+with applied voltage of 10V and further increase of voltage (20V) decreases the
+resistance to 8KOhm. We also analyzed the frequency response of the capacitor
+using impedance measurement which shows high frequency response and estimated
+capacitance is 120nF. We optimized the patterns by running the Lightscribe
+repeatedly on the GO coated PET substrate.",1409.6396v1
+2014-10-01,Varistor characteristics of a nano-device containing graphene and oxidized graphene: Verification by DFT + NEGF,"Electron transport and quantum conductance through an armchair graphene and
+its oxidized graphene- containing form were investigated by the density
+functional theory (DFT) method and the implementation of the non-equilibrium
+Green function (NEGF) approach. The computed $I-V_b$(current as a function of
+bias voltage) characteristic of the studied systems showed the tunneling
+phenomenon in bias and gate voltages considered. Along with the transport
+properties, electronic properties including density of states (DOS) were
+calculated in the studied systems. A close examination of the results showed
+that the $I-V_b$ curve for graphene behaved $I\propto V_be^{\lambda V_b}$ like
+at some bias voltages, while for the oxidized graphene-containing form, its
+trend was the same as that of a Voltage Dependent Resistor (VDR-VARiable
+resISTOR), $I\propto V_b^\beta$, at the whole range of the applied bias.",1410.0285v4
+2014-11-13,Graphene-Passivated Nickel as an Oxidation-Resistant Electrode for Spintronics,"We report on graphene-passivated ferromagnetic electrodes (GPFE) for spin
+devices. GPFE are shown to act as spin-polarized oxidation-resistant
+electrodes. The direct coating of nickel with few layer graphene through a
+readily scalable chemical vapour deposition (CVD) process allows the
+preservation of an unoxidized nickel surface upon air exposure. Fabrication and
+measurement of complete reference tunneling spin valve structures demonstrates
+that the GPFE is maintained as a spin polarizer and also that the presence of
+the graphene coating leads to a specific sign reversal of the
+magneto-resistance. Hence, this work highlights a novel oxidation-resistant
+spin source which further unlocks low cost wet chemistry processes for
+spintronics devices.",1411.3476v1
+2014-11-13,The characterization of Co-nanoparticles supported on graphene,"The results of density functional theory (DFT) calculations and measurements
+of X-ray photoelectron (XPS) and X-ray emission (XES) spectra of
+Co-nanoparticles dispersed on graphene/Cu composites are presented. It is found
+that for 0.02nm and 0.06nm Co coverage the Co atoms form islands which are
+strongly oxidized under exposure at the air. For Co (2nm) coverage the upper
+Co-layers is oxidized whereas the lower layers contacting with graphene is in
+metallic state. Therefore Co (2 nm) coverage induces the formation of
+protective oxide layer providing the ferromagnetic properties of Co
+nanoparticles which can be used as spin filters in spintronics devices.",1411.3611v3
+2014-12-05,Tuning the Band Gap in Silicene by Oxidation,"Silicene monolayers grown on Ag(111) surfaces demonstrate a band gap that is
+tunable by oxygen adatoms from semimetallic to semiconducting type. By using
+low-temperature scanning tunneling microscopy, it is found that the adsorption
+configurations and amounts of oxygen adatoms on the silicene surface are
+critical for band-gap engineering, which is dominated by different buckled
+structures in R13xR13, 4x4, and 2R3x2R3 silicene layers. The Si-O-Si bonds are
+the most energy-favored species formed on R13xR13, 4x4, and 2R3x2R3 structures
+under oxidation, which is verified by in-situ Raman spectroscopy as well as
+first-principles calculations. The silicene monolayers retain their structures
+when fully covered by oxygen adatoms. Our work demonstrates the feasibility of
+tuning the band gap of silicene with oxygen adatoms, which, in turn, expands
+the base of available two-dimensional electronic materials for devices with
+properties that is hardly achieved with graphene oxide.",1412.1886v1
+2014-12-05,"Oxidation of copper during physical sputtering deposition: mechanism, avoidance and utilization","In this paper, oxidation of Cu during physical sputtering deposition in a
+high purity and low pressure Ar atmosphere without introducing O2 gas flow was
+studied systemically. It was found that various flexible Cu-based films could
+be obtained by simply adjusting deposition parameters. Electrical and optical
+testing results showed that the achieved pure Cu films and Cu+Cu2O composite
+films both presented an intriguing combination of metal and semiconductor
+characteristics. It is expected that such Cu-based films with a superior
+conductivity and a solar-window bandgap may have fascinating potential
+applications such as in high electron mobility transistors, electrodes and
+solar cells. Further, the oxidation mechanisms of Cu under different deposition
+parameters and the main O2 source during physical sputtering deposition were
+also explored.",1412.2031v1
+2014-12-08,Evaluation of defects in cuprous oxide through exciton luminescence imaging,"The various decay mechanisms of excitons in cuprous oxide (Cu2O) are highly
+sensitive to defects which can relax selection rules. Here we report cryogenic
+hyperspectral imaging of exciton luminescence from cuprous oxide crystals grown
+via the floating zone method showing the samples have few defects. Some
+locations, however, show strain splitting of the 1s orthoexciton triplet
+polariton luminescence. Strain is reduced by annealing. In addition, annealing
+causes annihilation of oxygen and copper vacancies, which leads to a negative
+correlation between luminescence of unlike vacancies.",1412.2707v1
+2014-12-12,A Monolithic active pixel sensor for ionizing radiation using a 180nm HV-SOI process,"An improved SOI-MAPS (Silicon On Insulator Monolithic Active Pixel Sensor)
+for ionizing radiation based on thick-film High Voltage SOI technology (HV-SOI)
+has been developed. Similar to existing Fully Depleted SOI-based (FD-SOI) MAPS,
+a buried silicon oxide inter-dielectric (BOX) layer is used to separate the
+CMOS electronics from the handle wafer which is used as a depleted charge
+collection layer. FD-SOI MAPS suffer from radiation damage such as transistor
+threshold voltage shifts due to charge traps in the oxide layers and charge
+states created at the silicon oxide boundaries (back gate effect). The X-FAB
+180-nm HV-SOI technology offers an additional isolation by deep non-depleted
+implant between the BOX layer and the active circuitry witch mitigates this
+problem. Therefore we see in this technology a high potential to implement
+radiation-tolerant MAPS with fast charge collection property. The design and
+measurement results from a first prototype are presented including charge
+collection in neutron irradiated samples.",1412.3973v2
+2014-12-15,Percolation conductivity in hafnium sub-oxides,"In this study, we demonstrated experimentally that formation of chains and
+islands of oxygen vacancies in hafnium sub-oxides (HfO$_x$, $x<2$) leads to
+percolation charge transport in such dielectrics. Basing on the model of
+\'{E}fros-Shklovskii percolation theory good quantitative agreement between the
+experimental and theoretical data of current-voltage characteristics were
+achieved. Based on the percolation theory suggested model shows that hafnium
+sub-oxides consist of mixtures of metallic Hf nanoscale clusters of 1-2 nm
+distributed onto non-stoichiometric HfO$_x$. It was shown that reported
+approach might describe low resistance state current-voltage characteristics of
+resistive memory elements based on HfO$_x$.",1412.4478v1
+2015-01-08,Multi-Lattice Kinetic Monte Carlo Simulations from First-Principles: Reduction of the Pd(100) Surface Oxide by CO,"We present a multi-lattice kinetic Monte Carlo (kMC) approach that
+efficiently describes the atomistic dynamics of morphological transitions
+between commensurate structures at crystal surfaces. As an example we study the
+reduction of a $(\sqrt{5}\times \sqrt{5})R27^{\circ}$ PdO(101) overlayer on
+Pd(100) in a CO atmosphere. Extensive density-functional theory calculations
+are used to establish an atomistic pathway for the oxide reduction process.
+First-principles multi-lattice kMC simulations on the basis of this pathway
+fully reproduce the experimental temperature dependence of the reduction rate
+[Fernandes et al., Surf. Sci. 2014, 621, 31-39] and highlight the crucial role
+of elementary processes special to the boundary between oxide and metal
+domains.",1501.01710v1
+2015-01-28,Dimensional oxidation and modular completion of non-geometric type IIB action,"Utilizing a setup of type IIB superstring theory compactified on an
+orientifold of T^6/(Z2xZ2), we propose a modular invariant dimensional
+oxidation of the four-dimensional scalar potential. In the oxidized
+ten-dimensional supergravity action, the standard NS-NS and RR three form
+fluxes (H-, F-) as well as the non-geometric fluxes (Q-, P-) are found to
+nicely rearrange themselves to form generalized flux-combinations. As an
+application towards moduli stabilization, using the same S-duality invariant
+scalar potential, we examine the recently proposed No-Go theorem (in
+arXiv:1409.7075) about creating a mass-hierarchy between universal-axion and
+the dilaton relevant for axionic-inflation. Considering a two-field dynamics of
+universal axion and dilaton while assuming the other moduli/axions being
+stabilized, we find a part of the No-Go arguments to be quite robust even with
+the inclusion of non-geometric (Q-, P-) fluxes.",1501.07248v4
+2015-03-12,The influence of electron beam irradiation on the chemical and structural properties of medical grade Polyurethane,"Thermo plastic polyurethane (TPU) provides excellent bio-compatibility,
+flexibility and good irradiation resistance; however, extremely high
+irradiation doses can alter the structure and function of macromolecules,
+resulting in oxidation, chain scission and cross-linking. In this study, the
+effects of e-beam irradiation on the medical grade thermo plastic polyurethane
+were studied. The changes in the chain length and their distribution as well as
+the changes in molecular structure were studied. The GPC (Gel Permeation
+Chromatography) results show that the oxidative decomposition is followed by a
+decrease in molecular mass together with an increase in polydispersity. This
+indicates a very inhomogeneous degradation, which is a consequence of the
+specific course and of the intensity of oxidative degradation. This was
+confirmed by means of mechanical property measurements. Overall, this study
+demonstrated that the medical grade TPU was affected by radiation exposure,
+particularly at high irradiation doses.",1503.03590v1
+2015-03-16,Lithiation of Tin Oxide: A Computational Study,"We suggest that the lithiation of pristine SnO forms a layered Li$_\text{X}$O
+structure while the expelled tin atoms agglomerate into 'surface' planes
+separating the Li$_\text{X}$O layers. The proposed lithiation model widely
+differs from the common assumption that tin segregates into nano-clusters
+embedded in the lithia matrix. With this model we are able to account for the
+various tin bonds that are seen experimentally and explain the three volume
+expansion phases that occur when SnO undergoes lithiation: (i) at low
+concentrations Li behaves as an intercalated species inducing small volume
+increases; (ii) for intermediate concentrations SnO transforms into lithia
+causing a large expansion; (iii) finally, as the Li concentration further
+increases a saturation of the lithia takes place until a layered Li$_2$O is
+formed. A moderate volume expansion results from this last process. We also
+report a 'zipper' nucleation mechanism that could provide the seed for the
+transformation from tin oxide to lithium oxide.",1503.04647v1
+2015-03-25,"Identification of novel Cu, Ag, and Au ternary oxides from global structural prediction","We use ab initio global structural prediction, and specifically the minima
+hopping method, to explore the periodic table in search of novel oxide phases.
+In total, we study 183 different compositions of the form MXO2, where M=(Cu,
+Ag, Au) and X is an element of the periodic table. This set includes the
+well-known Cu delafossite compounds that are, up to now, the best p-type
+transparent conductive oxides known to mankind. Our calculations discover 81
+stable compositions, out of which only 36 are included in available databases.
+Some of these new phases are potentially good candidates for transparent
+electrodes. These results demonstrate, on one hand, how incomplete is still our
+knowledge of the phase-space of stable ternary materials. On the other hand, we
+show that structural prediction combined with high-throughput approaches is a
+powerful tool to extend that knowledge, paving the way for the experimental
+discovery of new materials on a large scale.",1503.07327v1
+2015-04-09,Spin responses and effective Hamiltonian for the two dimensional electron gas at oxide interface {LaAlO}$_3$/{SrTiO}$_3$,"Strong Rashba spin-orbit coupling (SOC) of the two-dimensional electron gas
+(2DEG) at the oxide interface $\mathrm{LaAlO_{3}/SrTiO_{3}}$ underlies a
+variety of exotic physics, but its nature is still under debate. We derive an
+effective Hamiltonian for the 2DEG at the oxide interface
+$\mathrm{LaAlO_{3}/SrTiO_{3}}$ and find a different anisotropic Rashba SOC for
+the $d_{xz}$ and $d_{yz}$ orbitals. This anisotropic Rashba SOC leads to
+anisotropic static spin susceptibilities and also distinctive behavior of the
+spin Hall conductivity. These unique spin responses may be used to determine
+the nature of the Rashba SOC experimentally and shed light on the orbital
+origin of the 2DEG.",1504.02177v3
+2015-04-13,Scaling Theory of Electrically Doped 2D Transistors,"In this letter, it is shown that the existing scaling theories for chemically
+doped transistors cannot be applied to the novel class of electrically doped 2D
+transistors and the concept of equivalent oxide thickness (EOT) is not
+applicable anymore. Hence, a novel scaling theory is developed based on
+analytic solutions of the 2D Poisson equation. Full band atomistic quantum
+transport simulations verify the theory and show that the critical design
+parameters are the physical oxide thickness and distance between the gates.
+Accordingly, the most optimized electrically doped devices are those with the
+smallest spacing between the gates and the thinnest oxide, and not the smallest
+EOT.",1504.03387v3
+2015-05-11,Oxide 2D electron gases as a route for high carrier densities on (001) Si,"Two dimensional electron gases (2DEGs) formed at the interfaces of oxide
+heterostructures draw considerable interest owing to their unique physics and
+potential applications. Growing such heterostructures on conventional
+semiconductors has the potential to integrate their functionality with
+semiconductor device technology. We demonstrate 2DEGs on a conventional
+semiconductor by growing $GdTiO_3-SrTiO_3$ on silicon. Structural analysis
+confirms the epitaxial growth of heterostructures with abrupt interfaces and a
+high degree of crystallinity. Transport measurements show the conduction to be
+an interface effect, with $\sim 9\times 10^{13} \; cm^{-2}$ electrons per
+interface. Good agreement is demonstrated between the electronic behavior of
+structures grown on Si and on an oxide substrate, validating the robustness of
+this approach to bridge between lab-scale samples to a scalable,
+technologically relevant materials system.",1505.02738v1
+2015-05-20,"III-V/Si Wafer Bonding Using Transparent, Conductive Oxide Interlayers","We present a method for low temperature plasma-activated direct wafer bonding
+of III-V materials to Si using a transparent, conductive indium zinc oxide
+interlayer. The transparent, conductive oxide (TCO) layer provides excellent
+optical transmission as well as electrical conduction, suggesting suitability
+for Si/III-V hybrid devices including Si-based tandem solar cells. For bonding
+temperatures ranging from 100$^{\circ}$C to 350$^{\circ}$C, Ohmic behavior is
+observed in the sample stacks, with specific contact resistivity below 1
+$\Omega$cm$^2$ for samples bonded at 200$^{\circ}$C. Optical absorption
+measurements show minimal parasitic light absorption, which is limited by the
+III-V interlayers necessary for Ohmic contact formation to TCOs. These results
+are promising for Ga$_{0.5}$In$_{0.5}$P/Si tandem solar cells operating at one
+sun or low concentration conditions.",1505.05453v2
+2015-05-29,Enhanced Li capacity in functionalized graphene: A first principle study with van der Waals correction,"We have investigated the adsorption of Li on graphene oxide using density
+functional theory. We show a novel and simple approach to achieve a positive
+lithiation potential on epoxy and hydroxyl functionalized graphene, compared to
+the negative lithiation potential that has been found on prestine graphene. We
+included the van der Waals correction into the calculation so as to get better
+picture of weak interactions. A positive lithiation potential suggests a
+favorable adsorption of Li on graphene oxide sheets that can lead to an
+increase in the specific capacity, which in turn can be used as an anode
+material in Li-batteries. We find a high specific capacity of ~860 mAh/g by
+functionalizing the graphene sheet. This capacity is higher than the previously
+reported capacities that were achieved on graphene with high concentration of
+Stone-Wales (75%) and divacancy (16%) defects. Creating such high density of
+defects can make the entire system energetically unstable, whereas graphene
+oxide is a naturally occurring substance.",1505.07918v1
+2015-06-18,Evidence for the Active Phase of Heterogeneous Catalysts through In Situ Reaction Product Imaging and Multiscale Modeling,"We use multi-scale modeling to analyze laser-induced fluorescence (LIF)
+measurements of the CO oxidation reaction over Pd(100) at near-ambient reaction
+conditions. Integrating density-functional theory based kinetic Monte Carlo
+simulations of the active catalyst into fluid-dynamical simulations of the mass
+transport inside the reactor chamber we calculate the reaction product
+concentration directly above the catalyst surface. Comparing corresponding data
+calculated for different surface models against the measured LIF signals we can
+discriminate the one that predominantly actuates the experimentally measured
+catalytic activity. For the probed CO oxidation reaction conditions the
+experimental activity is due to pristine Pd(100), possibly coexisting with
+other (oxidic) domains on the surface.",1506.05542v1
+2015-07-02,Low Operation Voltage Ferroelectric Field-Effect Transistor Based on Polarization Rotation Effect,"The effect of polarization rotation on the performance of metal oxide
+semiconductor field-effect transistors was investigated with a
+Landau-Ginzburg-Devonshire theory based model. In this analytical model,
+depolarization field, polarization rotations and the electrostatic properties
+of the doped silicon substrate are considered to illustrate the size effect of
+ferroelectric oxides and the stability of polarization in each direction. Based
+on this model, we demonstrate that MOSFET operation could be achieved by
+polarization reorientation with a low operating voltage, if the thickness of
+ferroelectric oxide is properly selected. Polarization reorientation can boost
+the surface potential of the silicon substrate, leading to a subthreshold swing
+S lower than 60 mV/decade. We believe that this model could provide guidance in
+designing electronic logic devices with low operating voltages and low active
+energy consumption.",1507.00764v1
+2015-07-07,The Effect of Polar Fluctuation and Lattice Mismatch on Carrier Mobility at Oxide Interfaces,"Since the discovery of two-dimensional electron gas (2DEG) at the oxide
+interface of LaAlO3/SrTiO3, improving carrier mobility has become an important
+issue for device applications. In this paper, by using an alternate polar
+perovskite insulator (La0.3Sr0.7)(Al0.65Ta0.35)O3 (LSAT) for reducing lattice
+mismatch from 3.0% to 1.0%, the low-temperature carrier mobility has been
+increased 30 fold to 35,000 cm2V-1s-1. Moreover, two critical thicknesses for
+the LSAT/SrTiO3 (001) interface are found: one at 5 unit cell for appearance of
+the 2DEG, the other at 12 unit cell for a peak in the carrier mobility. By
+contrast, the conducting (110) and (111) LSAT/STO interfaces only show a single
+critical thickness of 8 unit cells. This can be explained in terms of polar
+fluctuation arising from LSAT chemical composition. In addition to lattice
+mismatch and crystal symmetry at the interface, polar fluctuation arising from
+composition has been identified as an important variable to be tailored at the
+oxide interfaces to optimise the 2DEG transport.",1507.01675v1
+2015-07-11,Structure and Energetics of Graphene Oxide Isomers: Ab Initio Thermodynamic Analysis,"Graphene oxide (GO) holds significant promise for electronic devices and
+nanocomposite materials. A number of models were proposed for GO structure,
+combining carboxyl, hydroxyl, carbonyl and epoxide groups at different
+locations. The complexity and variety of GO isomers, whose thermodynamic
+stability and formation kinetics depend on applied conditions, make
+determination of GO structure with atomistic precision challenging. We report
+high level theoretical investigation of multiple molecular configurations,
+which are anticipated in GO. We conclude that all oxygen containing groups at
+the GO surface are thermodynamically permitted, whereas the edge positions are
+systematically more favorable than the center and side positions. We discuss a
+potentially novel type of chemical bond or bonding reinforcement in GO, which
+consists of a covalent bond and a strong electrostatic contribution from a
+polarized graphene plane. We observe and analyze significant modifications of
+graphene geometry and electronic structure upon oxidation. The reported
+thermodynamic data guide experiments aimed at deciphering GO chemical
+composition and structure, and form the basis for predicting GO properties
+required for nano-technological applications.",1507.03138v1
+2015-07-31,Surface Passivation in Empirical Tight Binding,"Empirical Tight Binding (TB) methods are widely used in atomistic device
+simulations. Existing TB methods to passivate dangling bonds fall into two
+categories: 1) Method that explicitly includes passivation atoms is limited to
+passivation with atoms and small molecules only. 2) Method that implicitly
+incorporates passivation does not distinguish passivation atom types. This work
+introduces an implicit passivation method that is applicable to any passivation
+scenario with appropriate parameters. This method is applied to a Si quantum
+well and a Si ultra-thin body transistor oxidized with SiO2 in several
+oxidation configurations. Comparison with ab-initio results and experiments
+verifies the presented method. Oxidation configurations that severely hamper
+the transistor performance are identified. It is also shown that the commonly
+used implicit H atom passivation overestimates the transistor performance.",1507.08712v1
+2015-08-10,"Electronic structure and phase stability of oxide semiconductors: Performance of dielectric-dependent hybrid functional DFT, benchmarked against $GW$ band structure calculations and experiments","We investigate band gaps, equilibrium structures, and phase stabilities of
+several bulk polymorphs of wide-gap oxide semiconductors ZnO, TiO2,ZrO2, and
+WO3. We are particularly concerned with assessing the performance of hybrid
+functionals built with the fraction of Hartree-Fock exact exchange obtained
+from the computed electronic dielectric constant of the material. We provide
+comparison with more standard density-functional theory and GW methods. We
+finally analyze the chemical reduction of TiO2 into Ti2O3, involving a change
+in oxide stoichiometry. We show that the dielectric-dependent hybrid functional
+is generally good at reproducing both ground-state (lattice constants, phase
+stability sequences, and reaction energies) and excited-state (photoemission
+gaps) properties within a single, fully ab initio framework.",1508.02174v2
+2015-09-13,Defect calculations in semiconductors through a dielectric-dependent hybrid DFT functional: the case of oxygen vacancies in metal oxides,"We investigate the behavior of oxygen vacancies in three different
+metal-oxide semiconductors (rutile and anatase TiO2, monoclinic WO3, and
+tetragonal ZrO2) using a recently proposed hybrid density-functional method in
+which the fraction of exact exchange is material-dependent but obtained ab
+initio in a self-consistent scheme. In particular, we calculate
+charge-transition levels relative to the oxygen-vacancy defect and compare
+computed optical and thermal excitation/emission energies with the available
+experimental results, shedding light on the underlying excitation mechanisms
+and related materials properties. We find that this novel approach is able to
+reproduce not only ground-state properties and band structures of perfect bulk
+oxide materials, but also provides results consistent with the optical and
+electrical behavior observed in the corresponding substoichiometric defective
+systems.",1509.03889v1
+2015-09-22,Antisite defects at oxide interfaces,"We use \textit{ab initio} calculations to estimate formation energies of
+cation (transition metal) antisite defects at oxide interfaces and to
+understand the basic physical effects that drive or suppress the formation of
+these defects. Antisite defects are found to be favored in systems with
+substantial charge transfer across the interface, while Jahn-Teller distortions
+and itinerant ferromagnetism can prevent antisite defects and help stabilize
+atomically sharp interfaces. Our results enable identification of classes of
+systems that may be more and less susceptible to the formation of antisite
+defects and motivate experimental studies and further theoretical calculations
+to elucidate the local structure and stability of oxide interface systems.",1509.06643v2
+2015-09-28,Phase Stability and Properties of Manganese Oxide Polymorphs: Assessment and Insights from Diffusion Monte Carlo,"We present an analysis of the polymorphic energy ordering and properties of
+the rock salt and zincblende structures of manganese oxide using fixed node
+diffusion Monte Carlo (DMC). Manganese oxide is a correlated, antiferromagnetic
+material that has proven to be challenging to model from first principles
+across a variety of approaches. Unlike conventional density functional theory
+and some hybrid functionals, fixed node diffusion Monte Carlo finds the rock
+salt structure to be more stable than the zincblende structure, and thus
+recovers the correct energy ordering. Analysis of the site-resolved charge
+fluctuations of the wave functions according to DMC and other electronic
+structure descriptions give insights into elements that are missing in other
+theories. While the calculated band gaps within DMC are in agreement with
+predictions that the zincblende polymorph has a lower band gap, the gaps
+themselves overestimate reported experimental values.",1509.08321v2
+2015-09-28,Conducting interfaces between amorphous oxide layers and SrTiO3(110) and SrTiO3(111),"Interfaces between (110) and (111)SrTiO3 (STO) single crystalline substrates
+and amorphous oxide layers, LaAlO3 (a-LAO), Y:ZrO2 (a-YSZ), and SrTiO3 (a-STO)
+become conducting above a critical thickness tc. Here we show that tc for a-LAO
+is not depending on the substrate orientation, i.e. tc (a-LAO/(110)STO) ~
+tc(a-LAO/(111)STO) interfaces, whereas it strongly depends on the composition
+of the amorphous oxide: tc(a-LAO/(110)STO) < tc(a-YSZ/(110)STO) <
+tc(a-STO/(110)STO). It is concluded that the formation of oxygen vacancies in
+amorphous-type interfaces is mainly determined by the oxygen affinity of the
+deposited metal ions, rather than orientational-dependent enthalpy vacancy
+formation and diffusion. Scanning transmission microscopy characterization of
+amorphous and crystalline LAO/STO(110) interfaces shows much higher amount of
+oxygen vacancies in the former, providing experimental evidence of the distinct
+mechanism of conduction in these interfaces.",1509.08385v1
+2015-09-30,Unusual dissociative adsorption of H2 over stoichiometric MgO thin film supported on molybdenum,"The dissociation of a hydrogen molecule on MgO(001) films deposited on
+Mo(001) surface is investigated systematically using periodic
+density-functional theory method. The unusual adsorption behavior of
+heterolytic dissociative hydrogen molecule at neighboring surface oxygen and
+surface magnesium, is clarified here. To my knowledge, this heterolytic
+dissociative state has never been found before on bulk MgO(001) or metal
+supported MgO(001) surfaces. The results confirm that, in all cases, the
+heterolytic dissociation is much more favorable that homolytic dissociation
+both energetically and kinetically. The energy difference between two
+dissociative states are very large, in the range of 1.1 eV ~ 1.5 eV for Mo
+supported 1 ML ~ 3 ML oxide films, which inhibits, to a great extent, the
+homolytic dissociation in the respect of reaction thermodynamics. The energy
+barrier of heterolytic dissociation are about 0.5 eV, much lower that the
+barrier of homolytic dissociation. The transformation reaction on thick films
+will be more endothermic. Passing through heterolytic dissociation state have
+significantly lowered the reaction heat and the energy barrier for obtaining
+homolytic dissociative structure, which make the homolytic splitting of H2
+easier on 2 ML oxide films. The results provides a useful strategy for
+enhancing the reactivity of the nonreducible metal oxide.",1509.09244v1
+2015-10-21,Proton Conducting Graphene Oxide Coupled Neuron Transistors for Brain-Inspired Cognitive Systems,"Neuron is the most important building block in our brain, and information
+processing in individual neuron involves the transformation of input synaptic
+spike trains into an appropriate output spike train. Hardware implementation of
+neuron by individual ionic/electronic hybrid device is of great significance
+for enhancing our understanding of the brain and solving sensory processing and
+complex recognition tasks. Here, we provide a proof-of-principle artificial
+neuron based on a proton conducting graphene oxide (GO) coupled oxide-based
+electric-double-layer (EDL) transistor with multiple driving inputs and one
+modulatory input terminal. Paired-pulse facilitation, dendritic integration and
+orientation tuning were successfully emulated. Additionally, neuronal gain
+control (arithmetic) in the scheme of rate coding is also experimentally
+demonstrated. Our results provide a new-concept approach for building
+brain-inspired cognitive systems.",1510.06115v1
+2015-11-20,Molecular beam epitaxy growth of SrO buffer layers on graphite and graphene for the integration of complex oxides,"We report the successful growth of high-quality SrO films on highly-ordered
+pyrolytic graphite (HOPG) and single-layer graphene by molecular beam epitaxy.
+The SrO layers have (001) orientation as confirmed by x-ray diffraction (XRD)
+while atomic force microscopy measurements show continuous pinhole-free films
+having rms surface roughness of <1.5 {\AA}. Transport measurements of
+exfoliated graphene after SrO deposition show a strong dependence between the
+Dirac point and Sr oxidation. Subsequently, the SrO is leveraged as a buffer
+layer for more complex oxide integration via the demonstration of (001)
+oriented SrTiO3 grown atop a SrO/HOPG stack.",1511.06496v1
+2016-01-08,On the nature of change in Ni oxidation state in BaTiO3-SrTiO3 system,"XAFS studies of Ni-doped Ba$_{1-x}$Sr$_x$TiO$_3$ solid solution reveal that
+the Ni oxidation state changes from 4 in SrTiO$_3$ to 2.5 in BaTiO$_3$ when
+varying $x$. This change is accompanied by a noticeable change in the
+interatomic Ni-O distances in the first shell. The first-principles
+calculations show that nickel creates an impurity band in the forbidden band
+gap of BaTiO$_3$ and SrTiO$_3$, which explains the appearance of intense
+absorption of Ni-doped samples in the visible region. The analysis of the
+electronic structure of doped crystals and calculations of the oxygen vacancy
+formation energy in them show that different oxidation states of Ni in
+SrTiO$_3$ and BaTiO$_3$ can be explained by different formation energies of the
+oxygen vacancies in these compounds.",1601.01961v2
+2016-02-17,Atomically flat reconstructed rutile TiO2(001) surfaces for oxide film growth,"The availability of low-index rutile TiO2 single crystal substrates with
+atomically flat surfaces is essential for enabling epitaxial growth of rutile
+transition metal oxide films. The high surface energy of the rutile (001)
+surface often leads to surface faceting, which precludes the sputter and
+annealing treatment commonly used for the preparation of clean and atomically
+flat TiO2(110) substrate surfaces. In this work, we reveal that stable and
+atomically flat rutile TiO2(001) surfaces can be prepared with an atomically
+ordered reconstructed surface already during a furnace annealing treatment in
+air. We tentatively ascribe this result to the decrease in surface energy
+associated with the surface reconstruction, which removes the driving force for
+faceting. Despite the narrow temperature window where this morphology can
+initially be formed, we demonstrate that it persists in homoepitaxial growth of
+TiO2(001) thin films. The stabilization of surface reconstructions that prevent
+faceting of high-surface-energy crystal faces may offer a promising avenue
+towards the realization of a wider range of high quality epitaxial transition
+metal oxide heterostructures.",1602.05518v1
+2016-04-19,Tuning the work function in transition metal oxides and their heterostructures,"The development of novel functional materials in experimental labs combined
+with computer-based compound simulation brings the vision of materials design
+on a microscopic scale continuously closer to reality. For many applications
+interface and surface phenomena rather than bulk properties are key. One of the
+most fundamental qualities of a material-vacuum interface is the energy
+required to transfer an electron across this boundary, i.e. the work function.
+It is a crucial parameter for numerous applications, including organic
+electronics, field electron emitters, and thermionic energy converters. Being
+generally very resistant to degradation at high temperatures, transition metal
+oxides present a promising materials class for such devices. We have performed
+a systematic study for perovskite oxides that provides reference values and,
+equally important, reports on materials trends and the tunability of work
+functions. Our results identify and classify dependencies of the work function
+on several parameters including specific surface termination, surface
+reconstructions, oxygen vacancies, and heterostructuring.",1604.05615v1
+2016-06-07,Enhancing Perovskite Electrocatalysis through Strain Tuning of the Oxygen Deficiency,"Oxygen vacancies in transition metal oxides facilitate catalysis critical for
+energy storage and generation. However, it has proven elusive to promote
+vacancies at the lower temperatures required for operation in devices such as
+metal-air batteries and portable fuel cells. Here, we use thin films of the
+perovskite-based strontium cobaltite (SrCoOx) to show that epitaxial strain is
+a powerful tool towards manipulating the oxygen content under conditions
+consistent with the oxygen evolution reaction, yielding increasingly oxygen
+deficient states in an environment where the cobaltite would normally be fully
+oxidized. The additional oxygen vacancies created through tensile strain
+enhance the cobaltite catalytic activity towards this important reaction by
+over an order of magnitude, equaling that of precious metal catalysts,
+including IrO2. Our findings demonstrate that strain in these oxides can
+dictate oxygen stoichiometry independent of ambient conditions, allowing
+unprecedented control over oxygen vacancies essential in catalysis near room
+temperature.",1606.02256v1
+2016-06-10,High throughput thermal conductivity of high temperature solid phases: The case of oxide and fluoride perovskites,"Using finite-temperature phonon calculations and machine-learning methods, we
+calculate the mechanical stability of about 400 semiconducting oxides and
+fluorides with cubic perovskite structures at 0 K, 300 K and 1000 K. We find 92
+mechanically stable compounds at high temperatures -- including 36 not
+mentioned in the literature so far -- for which we calculate the thermal
+conductivity. We demonstrate that the thermal conductivity is generally smaller
+in fluorides than in oxides, largely due to a lower ionic charge, and describe
+simple structural descriptors that are correlated with its magnitude.
+Furthermore, we show that the thermal conductivities of most cubic perovskites
+decrease more slowly than the usual $T^{-1}$ behavior. Within this set, we also
+screen for materials exhibiting negative thermal expansion. Finally, we
+describe a strategy to accelerate the discovery of mechanically stable
+compounds at high temperatures.",1606.03279v1
+2016-06-19,Controlling hybrid nonlinearities in transparent conducting oxides via two-colour excitation,"Nanophotonics and metamaterials have revolutionised the way we think about
+optical space (epsilon, mu), enabling us to engineer the refractive index
+almost at will, to confine light to the smallest of the volumes, and to
+manipulate optical signals with extremely small footprints and energy
+requirements. Significant efforts are now devoted to finding suitable materials
+and strategies for the dynamic control of the optical properties. Transparent
+conductive oxides exhibit large ultrafast nonlinearities under both interband
+and intraband excitations. Here, we show that combining these two effects in
+aluminium-doped zinc oxide via a two colour laser field discloses new material
+functionalities. Owing to the independence of the two nonlinearities the
+ultrafast temporal dynamics of the material permittivity can be designed by
+acting on the amplitude and delay of the two fields. We demonstrate the
+potential applications of this novel degree of freedom by dynamically
+addressing the modulation bandwidth and optical spectral tuning of a probe
+optical pulse.",1606.05824v3
+2016-06-23,Discovery of the Interstellar Chiral Molecule Propylene Oxide (CH$_3$CHCH$_2$O),"Life on Earth relies on chiral molecules, that is, species not superimposable
+on their mirror images. This manifests itself in the selection of a single
+molecular handedness, or homochirality, across the biosphere. We present the
+astronomical detection of a chiral molecule, propylene oxide (CH$_3$CHCH$_2$O),
+in absorption toward the Galactic Center. Propylene oxide is detected in the
+gas phase in a cold, extended molecular shell around the embedded, massive
+protostellar clusters in the Sagittarius B2 star-forming region. This material
+is representative of the earliest stage of solar system evolution in which a
+chiral molecule has been found.",1606.07483v1
+2016-07-19,Graphene and MoS2 interacting with water: a comparison by ab initio calculations,"Although very similar in many technological applications, graphene and MoS2
+bear significant differences if exposed to humid environments. As an example,
+lubrication properties of graphene are reported to improve while those of MoS2
+to deteriorate: it is unclear whether this is due to oxidation from disulfide
+to oxide or to water adsorption on the sliding surface. By means of ab initio
+calculations we show here that these two layered materials have similar
+adsorption energies for water on the basal planes. They both tend to avoid
+water intercalation between their layers and to display only mild reactivity of
+defects located on the basal plane. It is along the edges where marked
+differences arise: graphene edges are more reactive at the point that they
+immediately prompt water splitting. MoS2 edges are more stable and consequently
+water adsorption is much less favoured than in graphene. We also show that
+water-driven oxidation of MoS2 layers is unfavoured with respect to adsorption.",1607.05607v1
+2016-09-02,Controlling effective dimensionality and competition between spin liquid and chiral orders by new multiorbital effects in $S=\frac{1}{2}$ pyrochlore oxides,"In frustrated systems, some or many states are competed due to frustration of
+exchange interactions, and this competition often results in exotic states,
+such as spin liquid and chiral orders. We consider a pyrochlore oxide, a
+three-dimensional frustrated system, and study its $S=\frac{1}{2}$ effective
+model, consisting of the Heisenberg-type and Dzyaloshinsky-Moriya-type
+superexchange interactions between the nearest-neighbor transition-metal ions.
+We show that by using new multiorbital effects of the $t_{2g}$ orbitals on
+coefficients of those interactions, we can change the effective dimensionality
+from three-dimensional to two-dimensional, and control the competition between
+chiral orders and spin liquid. We also show that the new multiorbital effects
+are vital to stabilize three-in-one-out chiral order, distorted
+four-in-four-out chiral order, and distorted three-in-one-out chiral order, and
+can be used to hold macroscopic degeneracy, resulting in the spin liquid, even
+with the finite Dzyaloshinsky-Moriya interactions. Those results open up new
+multiorbital physics in spin systems, and make the essential step for the
+realistic mechanism for the spin liquid in pyrochlore oxides.",1609.00445v2
+2016-09-15,Accurate X-Ray Absorption Predictions for Transition Metal Oxides: An Advanced Self-Consistent-Field Approach Inspired by Many-Body Perturbation Theory,"Constrained-occupancy self-consistent-field ($\Delta$SCF) methods and
+many-body perturbation theories (MBPT) are two strategies for obtaining
+electronic excitations from first-principles. Using the two distinct
+approaches, we study the O $1s$ core excitations that have become increasingly
+important for characterizing transition metal oxides and developing theory of
+strong correlations. Interestingly, we find that the $\Delta$SCF approach, in
+its current single-particle form, systematically underestimates the pre-edge
+intensity for chosen oxides, despite its success in weakly correlated systems.
+By contrast, the Bethe-Salpeter equation within MBPT predicts much better
+lineshapes. This inspires us to reexamine the many-electron dynamics of X-ray
+excitations. We find that the single-particle $\Delta$SCF approach can be
+rectified by explicitly calculating many-body transition amplitudes, producing
+X-ray spectra in excellent agreement with experiments. Our study paves the way
+to accurately predict X-ray near-edge spectral fingerprints for physics and
+materials science beyond the Bethe-Salpether equation.",1609.04872v2
+2016-09-26,Effects of processing on the stability of molybdenum oxide ultra-thin films,"The effects of wet chemical processing conventionally employed in device
+fabrication standards are systematically studied on molybdenum oxide (MoOx)
+ultra-thin films. We have combined x-ray photoelectron spectroscopy (XPS),
+angle resolved XPS and x-ray reflectivity techniques to provide deep insights
+into the changes in composition, structure and electronic states upon treatment
+of films with different initial stoichiometry prepared by reactive sputtering.
+Our results show significant reduction effects associated with the development
+of gap states in MoOx, as well as changes in the composition, density and
+structure of the films, systematically correlated with the initial oxidation
+state of Mo.",1609.07993v1
+2016-10-17,Polydopamine-Coated TiO2 Nanotubes for Selective Photocatalytic Oxidation of Benzyl Alcohol to Benzaldehyde under Visible Light,"TiO2 nanotube arrays grown by anodization were coated with thin layers of
+polydopamine as visible light sensitizer. The PDA-coated TiO2 scaffolds were
+used as photocatalyst for selective oxidation of benzyl alcohol under
+monochromatic irradiation at 473 nm. Benzaldehyde was selectively formed and no
+by-products could be detected. A maximized reaction yield was obtained in
+O2-saturated acetonitrile. A mechanism is proposed that implies firstly the
+charge carrier generation in polydopamine as a consequence of visible light
+absorption. Secondly, photo-promoted electrons are injected in TiO2 conduction
+band, and subsequently transferred to dissolved O2 to form oxygen radical
+anions. These radicals react with benzyl alcohol and lead to its selective
+dehydrogenation oxidation towards benzaldehyde.",1610.05154v1
+2016-10-20,Stable Co-Catalyst-Free Photocatalytic H2 Evolution From Oxidized Titanium Nitride Nanopowders,"In the present work, a simple strategy is used to thermally oxidize TiN
+nanopowder (ca. 20 nm) to an anatase phase of a TiO2:Ti3+:N compound. In
+contrast to the rutile phase of such a compound this photocatalyst provides
+photocatalytic activity for hydrogen evolution under AM1.5 conditions - this
+without the use of any noble metal co-catalyst. Moreover the photocatalyst is
+active and stable over extended periods of time (tested for 4 months).
+Importantly, to achieve successful conversion to the active anatase polymorph,
+sufficiently small starting particles of TiN are needed. The key factor for
+catalysis is the stabilization of the co-catalytically active Ti3+ species
+against oxidation by nitrogen present in the starting material.",1610.06335v1
+2016-10-20,Self-ordered Mo-oxide Nanotube Arrays as Precursor for Aligned MoOx/MoS2 Core-Shell Nanotubular Structures with a High Density of Reactive Sites,"In the present work we demonstrate the self-organized formation of anodic
+Mo-oxide nanotube arrays grown on a Mo sheet under suitable electrochemical
+conditions in glycerol/NH4F electrolytes. The resulting amorphous tubes can be
+crystallized by annealing to MoO2 or MoO3. The tube walls then can be further
+sulfurized fully or partially to Mo-sulfide to form well-ordered arrays of
+vertically aligned MoOx/MoS2 nanotubes. Under optimized conditions, defined
+MoS2 sheets form on the oxide walls in a layer by layer low angle zig-zag
+arrangement that provide a high density of reactive stacking faults. These
+core-shell nanotube arrays, consisting of tubes with a conductive suboxide core
+and a functional high defect density MoS2 coating, are highly promising for
+applications such as electrocatalysis (hydrogen evolution) or ion insertion
+devices.",1610.06350v1
+2016-10-21,Constructing oxide interfaces and heterostructures by atomic layer-by-layer laser molecular beam epitaxy,"Advancements in nanoscale engineering of oxide interfaces and
+heterostructures have led to discoveries of emergent phenomena and new
+artificial materials. Combining the strengths of reactive molecular-beam
+epitaxy and pulsed-laser deposition, we show here, with examples of
+Sr1+xTi1-xO3+delta, Ruddlesden-Popper phase Lan+1NinO3n+1 (n = 4), and
+LaAl1+yO3(1+0.5y)/SrTiO3 interfaces, that atomic layer-by-layer laser
+molecular-beam epitaxy (ALL-Laser MBE) significantly advances the state of the
+art in constructing oxide materials with atomic layer precision and control
+over stoichiometry. With ALL-Laser MBE we have produced conducting
+LaAlO3/SrTiO3 interfaces at high oxygen pressures that show no evidence of
+oxygen vacancies, a capability not accessible by existing techniques. The
+carrier density of the interfacial two-dimensional electron gas thus obtained
+agrees quantitatively with the electronic reconstruction mechanism.",1610.06885v1
+2016-10-26,Hydrogen release at metal-oxide interfaces: A first principle study of hydrogenated Al/SiO$_2$ interfaces,"The Anode Hydrogen Release (AHR) mechanism at interfaces is responsible for
+the generation of defects, that traps charge carriers and can induce dielectric
+breakdown in Metal-Oxide-Semiconductor Field Effect Transistors. The AHR has
+been extensively studied at Si/SiO$_2$ interfaces but its characteristics at
+metal-silica interfaces remain unclear. In this study, we performed Density
+Functional Theory (DFT) calculations to study the hydrogen release mechanism at
+the typical Al/SiO$_2$ metal-oxide interface. We found that interstitial
+hydrogen atoms can break interfacial Al-Si bonds, passivating a Si $sp^3$
+orbital. Interstitial hydrogen atoms can also break interfacial Al-O bonds, or
+be adsorbed at the interface on aluminum, forming stable Al-H-Al bridges. We
+showed that hydrogenated O-H, Si-H and Al-H bonds at the Al/SiO$_2$ interfaces
+are polarized. The resulting bond dipole weakens the O-H and Si-H bonds, but
+strengthens the Al-H bond under the application of a positive bias at the metal
+gate. Our calculations indicate that Al-H bonds and O-H bonds are more
+important than Si-H bonds for the hydrogen release process.",1610.08365v1
+2016-10-28,Hard X-rays as pump and probe of atomic motion in oxide glasses,"Nowadays powerful X-ray sources like synchrotrons and free-electron lasers
+are considered as ultimate tools for probing microscopic properties in
+materials. However, the correct interpretation of such experiments requires a
+good understanding on how the beam affects the properties of the sample,
+knowledge that is currently lacking for intense X-rays. Here we use X-ray
+photon correlation spectroscopy to probe static and dynamic properties of oxide
+and metallic glasses. We find that although the structure does not depend on
+the flux, strong fluxes do induce a non-trivial microscopic motion in oxide
+glasses, whereas no such dependence is found for metallic glasses. These
+results show that high fluxes can alter dynamical properties in hard materials,
+an effect that needs to be considered in the analysis of X-ray data but which
+also gives novel possibilities to study materials properties since the beam can
+not only be used to probe the dynamics but also to pump it.",1610.09236v1
+2017-03-16,"Mitochondrial oxidative phosphorylation: Debunking the concepts of electron transport chain, proton pumps, chemiosmosis and rotary ATP synthesis","Herein (the first part of my work), I debunk the long-standing hypotheses
+that explain mitochondrial oxidative phosphorylation. Simple calculations point
+out that mitochondria are highly proton-deficient microcosms and therefore,
+elaborate proton pump machinery are not tenable. Further, other elements like
+the elaborate electron transport chain, chemiosmosis, rotary ATP synthesis,
+etc. are also critically evaluated to point out that such complicated systems
+are non-viable. The communication necessitates a new explanatory paradigm for
+cellular respiration. In the second part of my work, I have put forward a
+viable alternative explanatory paradigm for mitochondrial oxidative
+phosphorylation.",1703.05826v1
+2017-08-18,First principles study of oxidation of Si segregated α-Ti(0001) surfaces,"The oxidation of {\alpha}-Ti(0001) surface was studied using density
+functional theory. In order to enhance the oxidation resistance, we substituted
+Ti atoms with Si atoms in Ti(0001) surface. We observe that Si prefers to
+segregate at the surface layer of Ti(0001) compared to other sub-surface
+layers. The Si solubility on the Ti(0001) surface was estimated to be around 75
+at.%. While Si segregation was found to reduce the binding between the oxygen
+atom and the Ti(0001) surface, the barrier for oxygen to diffuse into the slab
+increases. The dissociation of the oxygen molecule on the clean and Si
+segregated surfaces of Ti was found to be barrier-less. Overall, the Si
+segregation on the Ti(0001) surface was found to hinder the dissolution of
+oxygen in Ti.",1708.05481v1
+2018-04-10,Phosphorus oxide gate dielectric for black phosphorus field effect transistors,"The environmental stability of the layered semiconductor black phosphorus
+(bP) remains a challenge. Passivation of the bP surface with phosphorus oxide,
+POx, grown by a reactive ion etch with oxygen plasma is known to improve
+photoluminescence efficiency of exfoliated bP flakes. We apply phosphorus oxide
+passivation in the fabrication of bP field effect transistors using a gate
+stack consisting of a POx layer grown by reactive ion etching followed by
+atomic layer deposition of Al2O3. We observe room temperature top-gate
+mobilities of 115 cm2/Vs in ambient conditions, which we attribute to the low
+defect density of the bP/POx interface.",1804.03639v1
+2018-04-13,Reaction of O2 with Subsurface Oxygen Vacancies on TiO2 Anatase (101),"Oxygen (O2) adsorbed on metal oxides is important in catalytic oxidation
+reactions, chemical sensing, and photocatalysis. Strong adsorption requires
+transfer of negative charge from oxygen vacancies (VOs) or dopants, for
+example. With scanning tunneling microscopy, we observed, transformed, and, in
+conjunction with theory, identified the nature of O2 molecules on the (101)
+surface of anatase (titanium oxide, TiO2) doped with niobium. VOs reside
+exclusively in the bulk, but we pull them to the surface with a strongly
+negatively charged scanning tunneling microscope tip. O2 adsorbed as superoxo
+(O2)- at fivefold-coordinated Ti sites was transformed to peroxo (O2)2- and,
+via reaction with a VO, placed into an anion surface lattice site as an (O2)O
+species. This so-called bridging dimer also formed when O2 directly reacted
+with VOs at or below the surface.",1804.04926v1
+2018-04-16,Adsorption of water at the SrO surface of ruthenates,"Although perovskite oxides hold promise in applications ranging from solid
+oxide fuel cells to catalysts, their surface chemistry is poorly understood at
+the molecular level. Here we follow the formation of the first monolayer of
+water at the (001) surfaces of Sr$_{n+1}$Ru$_n$O$_{3n+1}$ ($n$ = 1, 2) using
+low-temperature scanning tunnelling microscopy, X-ray photoelectron
+spectroscopy, and density functional theory. These layered perovskites cleave
+between neighbouring SrO planes, yielding almost ideal, rocksalt-like surfaces.
+An adsorbed monomer dissociates and forms a pair of hydroxide ions. The OH
+stemming from the original molecule stays trapped at Sr-Sr bridge positions,
+circling the surface OH with a measured activation energy of 187 $\pm$ 10 meV.
+At higher coverage, dimers of dissociated water assemble into one-dimensional
+chains and form a percolating network where water adsorbs molecularly in the
+gaps. Our work shows the limitations of applying surface chemistry concepts
+derived for binary rocksalt oxides to perovskites.",1804.05612v1
+2018-10-31,Probing itinerant antiferromagnetism with $d$-wave Andreev reflection spectroscopy,"To study how Andreev reflection (AR) is affected by itinerant
+antiferromagnetism, we perform $d$-wave AR spectroscopy with superconducting
+YBa$_2$Cu$_3$O$_{7-\delta}$ on TiAu and on variously-oxidized Nb (NbO$_x$)
+samples. X-ray photoelectron spectroscopy is also used on the latter to measure
+their surface oxide composition. Below the N\'eel temperatures ($T_N$) of both
+TiAu and NbO$_x$, the conductance spectra show a dip-like structure instead of
+a zero-bias peak within the superconducting energy gap; for NbO$_x$,
+higher-oxidized samples show a stronger spectral dip at zero bias. These
+observations indicate that itinerant antiferromagnetic order suppresses the AR
+process. Interestingly, the spectral dip persists above $T_N$ for both TiAu and
+NbO$_x$, implying that spin fluctuations can also suppress AR. Our results
+suggest that $d$-wave AR spectroscopy may be used to probe the degree of spin
+ordering in itinerant antiferromagnets.",1811.00160v1
+2018-11-07,Inverted orbital polarization in strained correlated oxide films,"Manipulating the orbital occupation of valence electrons via epitaxial strain
+in an effort to induce new functional properties requires considerations of how
+changes in the local bonding environment affect the band structure at the Fermi
+level. Using synchrotron radiation to measure the x-ray linear dichroism of
+epitaxially strained films of the correlated oxide CaFeO3, we demonstrate that
+the orbital polarization of the Fe valence electrons is opposite from
+conventional understanding. Although the energetic ordering of the Fe 3d
+orbitals is confirmed by multiplet ligand field theory analysis to be
+consistent with previously reported strain-induced behavior, we find that the
+nominally higher energy orbital is more populated than the lower. We ascribe
+this inverted orbital polarization to an anisotropic bandwidth response to
+strain in a compound with nearly filled bands. These findings provide an
+important counterexample to the traditional understanding of strain-induced
+orbital polarization and reveal a new method to engineer otherwise unachievable
+orbital occupations in correlated oxides.",1811.03075v1
+2018-11-14,Direct observation of state-filling at hybrid tin oxide/organic interfaces,"Electroluminescence (EL) spectra from hybrid charge transfer excitons at
+metal oxide/organic type-II heterojunctions exhibit pronounced bias-induced
+spectral shifts. The reasons for this phenomenon have been discussed
+controversially and arguments for both electric field-induced effects as well
+as filling of trap states at the oxide surface have been put forward. Here, we
+combine the results from EL and photovoltaic measurements to eliminate the
+disguising effects of the series resistance. For SnOx combined with the
+conjugated polymer MeLPPP, we find a one-to-one correspondence between the
+blueshift of the EL peak and the increase of the quasi-Fermi level splitting at
+the hybrid heterojunction, which we unambiguously assign to state filling. Our
+data is resembled best by a model considering the combination an exponential
+density of states with a doped semiconductor.",1811.05880v2
+2018-11-30,Nanonionics and interfaces for energy and information technologies,"There is a growing interest in the development of functional metal oxides
+with mixed ionic electronic conduction for their application in different
+strategic fields. In particular, ionic transport-related phenomena are of
+primary importance in energy transformation and storage devices, such as solid
+oxides fuel cells (SOFC) or batteries. Traditionally, the main issue that
+hindered a wide spread of solid state electrochemical devices is the slow ionic
+conduction and the reduced number of families of materials with pure ionic
+conductivity able to play the role of the electrolyte. This is due to the low
+mobility of the ionic charge carriers and their mechanical and coulombic
+interactions with their host crystal structures. For relatively big and charged
+ions, e.g. O2- or Na+, the low ionic conductivity imposes operating at high
+temperatures, which is incompatible with some applications such as portable
+electronics.",1811.12744v1
+2019-04-30,Ultrathin complex oxide nanomechanical resonators,"Complex oxide thin films and heterostructures exhibit a profusion of exotic
+phenomena, often resulting from the intricate interplay between film and
+substrate. Recently it has become possible to isolate epitaxially grown
+single-crystalline layers of these materials, enabling the study of their
+properties in the absence of interface effects. In this work, we create
+ultrathin membranes of strongly correlated materials and demonstrate top-down
+fabrication of nanomechanical resonators made out of \ce{SrTiO3} and
+\ce{SrRuO3}. Using laser interferometry, we successfully actuate and measure
+the motion of the nanodrum resonators. By measuring their temperature-dependent
+mechanical response, we observe signatures of structural phase transitions in
+\ce{SrTiO3}, which affect the strain and mechanical dissipation in the
+resonators. This approach can be extended to investigate phase transitions in a
+wide range of materials. Our study demonstrates the feasibility of integrating
+ultrathin complex oxide membranes for realizing nanoelectromechanical systems
+on arbitrary substrates.",1905.00056v1
+2019-05-02,The pH Dependence of Ultrafast Charge Dynamics in Graphene Oxide Dispersions,"The pH dependence of emission from graphene oxide is believed to be due to
+the protonation of surface functional groups. In this study we use transient
+absorption spectroscopy to study the sub-picosecond charge dynamics in graphene
+oxide over a range of pH values, observing dynamics consistent with an excited
+state protonation step for pH < 9.3. The timescale of this process is ~ 1.5 ps,
+and a corresponding change in recombination dynamics follows. A broad
+photo-induced absorption peak centred at 530 nm associated with excited state
+protonation is also observed.",1905.00859v1
+2019-05-08,Synergetic Behavior in 2D Layered Material/Complex Oxide Heterostructures,"The marriage between a two-dimensional layered material (2DLM) and a complex
+transition metal oxide (TMO) results in a variety of physical and chemical
+phenomena that would not have been achieved in either material alone.
+Interesting recent discoveries in systems such as graphene/SrTiO3,
+graphene/LaAlO3/SrTiO3, graphene/ferroelectric oxide, MoS2/SrTiO3, and
+FeSe/SrTiO3 heterostructures include voltage scaling in field-effect
+transistors, charge state coupling across an interface, quantum conductance
+probing of the electrochemical activity, novel memory functions based on charge
+traps, and greatly enhanced superconductivity. In this progress report, we
+review various properties and functionalities appearing in numerous different
+2DLM/TMO heterostructure systems. The results imply that the multidimensional
+heterostructure approach based on the disparate material systems leads to an
+entirely new platform for the study of condensed matter physics and materials
+science. The heterostructures are also highly relevant technologically, as each
+constituent material is a promising candidate for next-generation
+opto-electronic devices.",1905.02930v1
+2020-07-02,Effects of Alloying Elements on Surface Oxides of Hot-Dip Galvanized Press Hardened Steel,"Effects of steel alloying elements on the formation of the surface oxide
+layer of hot-dip galvanized press hardened steel after austenitization
+annealing were examined with various advanced microscopy and spectroscopy
+techniques. The main oxides on top of the original thin Al2O3 layer,
+originating from the primary galvanizing process, are identified as ZnO and
+(Mn,Zn)Mn2O4 spinel. For some of the investigated steel alloys, a non-uniform,
+several nanometer thick Cr enriched, additional film was found at the Al2O3
+layer. At a sufficiently high concentration, Cr can act as a substitute for Al
+during annealing, strengthening and regenerating the original Al2O3 layer with
+Cr2O3. Further analysis with secondary ion mass spectrometry allowed a reliable
+distinction between ZnO and Zn(OH)2.",2007.01050v1
+2020-07-15,Atomic origin for hydrogenation promoted bulk oxygen vacancies removal in vanadium dioxide,"Oxygen vacancies (VO), a common type of point defects in metal oxides
+materials, play important roles on the physical and chemical properties. To
+obtain stoichiometric oxide crystal, the pre-existing VO is always removed via
+careful post-annealing treatment at high temperature in air or oxygen
+atmosphere. However, the annealing conditions is difficult to control and the
+removal of VO in bulk phase is restrained due to high energy barrier of VO
+migration. Here, we selected VO2 crystal film as the model system and developed
+an alternative annealing treatment aided by controllable hydrogen doping, which
+can realizes effective removal of VO defects in VO2-{\delta} crystal at lower
+temperature. This finding is attributed to the hydrogenation accelerated oxygen
+vacancies recovery in VO2-{\delta} crystal. Theoretical calculations revealed
+that the H-doping induced electrons are prone to accumulate around the oxygen
+defects in VO2-{\delta} film, which facilitates the diffusion of VO and thus
+makes it easier to be removed. The methodology is expected to be applied to
+other metal oxides for oxygen-related point defects control.",2007.07505v1
+2020-07-27,The effect of manganese and silicon additions on the corrosion resistance of a polycrystalline nickel-based superalloy,"The service lives of nickel superalloys are often limited by environmental
+degradation. The present study compares oxidation, sulfidation and hot
+corrosion at 750C of three variants of a polycrystalline superalloy: a baseline
+alloy, a variant containing 1wt% Mn and one containing 0.5wt% Si. Mn reduced
+the oxidation rate without changing the scale morphology. The MnCr2O4 scale
+formed proved more protective against sulfidation and hot corrosion, but
+internal sulfides extended the damage depth. Si modified the oxide morphology
+to a continuous Cr2O3-Al2O3 dual layer. This provided improved protection,
+reducing the sulfidation depth by 2/3 and the hot corrosion depth by 1/2.",2007.13416v1
+2010-05-04,Sub-monolayer nucleation and growth of complex oxide heterostructures at high supersaturation and rapid flux modulation,"We report on the non-trivial nanoscale kinetics of the deposition of novel
+complex oxide heterostructures composed of a unit-cell thick correlated metal
+LaNiO3 and dielectric LaAlO3. The multilayers demonstrate exceptionally good
+crystallinity and surface morphology maintained over the large number of
+layers, as confirmed by AFM, RHEED, and synchrotron X-ray diffraction. To
+elucidate the physics behind the growth, the temperature of the substrate and
+the deposition rate were varied over a wide range and the results were treated
+in the framework of a two-layer model. These results are of fundamental
+importance for synthesis of new phases of complex oxide heterostructures.",1005.0570v1
+2010-05-08,Femtosecond Photoexcited Carrier Dynamics in Reduced Graphene Oxide Suspensions and Films,"We report ultrafast response of femtosecond photoexcited carriers in single
+layer reduced graphene oxide flakes suspended in water as well as few layer
+thick film deposited on indium tin oxide coated glass plate using pump-probe
+differential transmission spectroscopy at 790 nm. The carrier relaxation
+dynamics has three components: ~200 fs, 1 to 2 ps, and ~25 ps, all of them
+independent of pump fluence. It is seen that the second component (1 to 2 ps)
+assigned to the lifetime of hot optical phonons is larger for graphene in
+suspensions whereas other two time constants are the same for both the
+suspension and the film. The value of third order nonlinear susceptibility
+estimated from the pump-probe experiments is compared with that obtained from
+the open aperture Z-scan results for the suspension.",1005.1322v2
+2013-08-04,Shungite as loosely packed fractal nets of graphene-based quantum dots,"The current paper presents the first attempt to recreate the origin of
+shungite carbon at microscopic level basing on knowledge accumulated by
+graphene science. The main idea of our approach is that different efficacy of
+chemical transformation of primarily generated graphene flakes (aromatic
+lamellae in geological literature), subjected to oxidation/reduction reactions
+in aqueous environment, lays the foundation of the difference in graphite and
+shungite derivation under natural conditions. Low-efficient reactions in the
+case of graphite do not prevent from the formation of large graphite layers
+while high-efficient oxidation/reduction transforms the initial graphene flakes
+into those of reduced graphene oxide of ~1nm in size. Multistage aggregation of
+these basic structural units, attributed to graphene quantum dots of shungite,
+leads to the fractal structure of shungite carbon thus exhibiting it as a new
+allotrope of natural carbon. The suggested microscopic view has finds a
+reliable confirmation when analyzing the available empirical data.",1308.0794v1
+2013-08-22,Symmetry-Tunable Environment in Functional Ferroic Heterostructures,"We demonstrate a concept for post-growth symmetry control in oxide
+heterostructures. A functional oxide is sandwiched between two ferroelectric
+layers and inversion symmetry at the position of the oxide constituent is
+reversibly switched on or off by layer-selective electric-field poling. The
+functionality of this process is monitored by optical second harmonic
+generation. The generalization of our approach to other materials and
+symmetries is considered. We thus establish ferroic trilayer structures as
+device components in which symmetry-driven charge-, spin-, and strain-related
+functionalities can be activated and deactivated at will.",1308.4796v1
+2013-08-29,Niobium-based sputtered thin films for Corrosion Protection of proton-irradiated liquid water targets for [18F] production,"Chemically inert Coatings on Havar entrance foils of the targets for [18F]
+production via proton irradiation of enriched water at pressurized conditions
+are needed to decrease the amount of ionic contaminants released from Havar. In
+order to find the most effective protective coatings, the Nb-based coating
+microstructure and barrier properties have been correlated with deposition
+parameters as: substrate temperature, applied bias, deposition rate and
+sputtering gas pressure. Aluminated quartz used as a substrate allowed us to
+verify the protection efficiency of the desirable coatings as diffusion
+barriers. Two modeling corrosion tests based on the extreme susceptibility of
+aluminum to liquid gallium and acid corrosion were applied. Pure Niobium
+coatings have been found less effective barriers than Niobium-titanium
+coatings. But Niobium oxide films, according to the corrosion tests performed,
+showed superior barrier properties. Therefore Multi-layered Niobium-Niobium
+oxide films have been suggested, since they combine the high thermal
+conductivity of Niobium with the good barrier properties of Niobium oxide.",1308.6605v1
+2014-03-14,Holographic patterning of graphene-oxide films by light-driven reduction,"We report on the patterning and reduction of graphene-oxide films by
+holographic lithography. Light reduction can be used to engineer low-cost
+graphene-based devices by performing a local conversion of insulating oxide
+into the conductive graphene. In this work, computer generated holograms have
+been exploited to realize complex graphene patterns in a single shot,
+differently from serial laser writing or mask-based photolithographic
+processes. The technique has been further improved by achieving speckle noise
+reduction: submicron and diffraction-limited features have been obtained. In
+addition we have also demonstrated that the gray-scale lithography capability
+can be used to obtain different reduction levels in a single exposure.",1403.3504v1
+2016-11-09,Interfacial interaction in monolayer transition metal dichalcogenides (MX2)/metal oxide heterostructures and its effects on electronic and optical properties: The case of MX2/CeO2,"Two-dimensional transition metal dichalcogenides (MX2)/metal oxide
+heterostructures have shown unique physical properties, making them promising
+materials for various applications ranging from photocatalysis to solar energy
+conversion. Understanding the interfacial interactions is highly desirable for
+designing these heterostructures having excellent performance. Here we
+systematically study the interfacial interaction in monolayer MX2 (M=Mo, W;
+X=S, Se)/CeO2 heterostructures and its effects on electronic and optical
+properties by density functional theory. It is found that the interfacial
+interaction in the MX2/CeO2 depends predominantly on the chalcogen (X) element.
+Particularly, the band gap variation and important electronic states at
+conduction band minimum or valence band maximum of the heterostructures are
+determined by the strength of interfacial interaction. The MX2/CeO2
+heterostructures with the same chalcogen (X) element have similar absorption
+spectra from ultraviolet to near-infrared regions. These results suggest that
+the chalcogen (X) element is a key factor in tuning the properties of MX2/metal
+oxide heterostructures.",1611.02799v1
+2016-11-10,First principle thermodynamic study of oxygen vacancy at metal/oxide interface,"The oxygen vacancy is a crucial intrinsic defect in metal-ultrathin oxide
+semiconductor heterostructures, and its formation at an interface is of great
+importance in determining the device performance and degradation. This paper
+presents an ab initio thermodynamic study of oxygen vacancies at metal/oxide
+interfaces. Electronic energies and entropies are calculated for defective
+interface systems, as a function of interface-vacancy distance. The study
+indicates that oxygen vacancies near the interface modify its bonding
+structure, and significantly change the thermodynamic properties of the system
+(i.e., electronic energy and entropy) compared to bulk-like oxygen vacancies.
+We illustrate that different factors, including the vacancy location dependence
+on the energy and entropy, the temperature dependence on the entropy, and the
+temperature and partial pressure dependence on the oxygen chemical potential,
+are all important in determining the Gibbs free energy of formation of oxygen
+vacancy.",1611.03411v1
+2016-11-24,In-situ Atom Probe Deintercalation of Lithium-Manganese-Oxide,"Atom probe tomography is routinely used for the characterisation of materials
+microstructures usually assuming that the microstructure is unaltered by the
+analysis. When analysing ionic conductors, however, gradients in the chemical
+potential and the electric field penetrating dielectric atom probe specimens
+can cause significant ionic mobility. While ionic mobility is undesired when
+aiming for materials characterisation it offers a strategy to manipulate
+materials directly in-situ in the atom probe. Here, we present experimental
+results on the analysis of the ionic conductor Lithium-Manganese-Oxide with
+different atom probe techniques. We demonstrate that at a temperature of 30K
+characterisation of the materials microstructure is possible without measurable
+Li mobility. Contrary, we show that at 298K the material can be deintercalated
+in-situ in the atom probe without changing the Manganese-Oxide host structure.
+Combining in-situ atom probe deintercalation and subsequent conventional
+characterisation we demonstrate a new methodological approach to study ionic
+conductors even in early stages of deintercalation.",1611.08114v1
+2016-11-27,Vacancy Relaxation in Cuprous Oxide (Cu$_{2-x}$O$_{1-y}$),"Phonons are produced when an excited vacancy in cuprous oxide (Cu$_2$O)
+relaxes. Time resolved luminescence was used to find the excited copper vacancy
+(acceptor) and oxygen vacancy (donor) trap levels and lifetimes. It was also
+used to determine the typical energy and number of phonons in the phonon pulses
+emitted by vacancies. The vacancy properties of cuprous oxide are controlled by
+several synthesis parameters and by the temperature. We directly demonstrate
+the absorption of light by oxygen vacancies with transient absorption. Copper
+and oxygen vacancies behave differently, in part because the two kinds of traps
+capture carriers from different states. For example, the copper vacancy
+luminescence lifetime is around 25 times greater at low temperature. However,
+both kinds of vacancy luminescence are consistent with a Poissonian multiple
+phonon emission model.",1611.08793v2
+2016-11-30,Band bending at the interface in Polyethylene-MgO nanocomposite dielectric,"Polymer nanocomposite dielectrics are promising materials for electrical
+insulation in high voltage applications. However, the physics behind their
+performance is not yet fully understood. We use density functional theory to
+investigate electronic properties of the interfacial area in magnesium
+oxide-polyethylene nanocomposite. Our results demonstrate polyethylene
+conduction band matching with conduction bands of different surfaces of
+magnesium oxide. Such band bending results in long range potential wells of up
+to 2.6 eV deep. Furthermore, the fundamental influence of silicon treatment on
+magnesium oxide surface properties is assessed. We report a reduction of the
+surface-induced states at the silicon-treated interface. The simulations
+provide information used to propose a new model for charge trapping in
+nanocomposite dielectrics.",1611.10251v1
+2017-01-03,Rapid laser-induced photochemical conversion of sol-gel precursors to In2O3 layers and their application in thin-film transistors,"We report the development of indium oxide (In2O3) transistors via a single
+step laser-induced photochemical conversion process of a sol-gel metal oxide
+precursor. Through careful optimization of the laser annealing conditions we
+demonstrated successful conversion of the precursor to In2O3 and its subsequent
+implementation in n-channel transistors with electron mobility up to 13 cm2/Vs.
+Importantly, the process does not require thermal annealing making it
+compatible with temperature sensitive materials such as plastic. On the other
+hand, the spatial conversion/densification of the sol-gel layer eliminates
+additional process steps associated with semiconductor patterning and hence
+significantly reduces fabrication complexity and cost. Our work demonstrates
+unambiguously that laser-induced photochemical conversion of sol-gel metal
+oxide precursors can be rapid and compatible with large-area electronics
+manufacturing.",1701.00859v1
+2017-01-07,"Spatially uniform resistance switching of low current, high endurance titanium-niobium-oxide memristors","We analyzed micrometer-scale titanium-niobium-oxide prototype memristors,
+which exhibited low write-power (<3 {\mu}W) and energy (<200 fJ/bit/{\mu}m2),
+low read-power (~nW), and high endurance (>millions of cycles). To understand
+their physico-chemical operating mechanisms, we performed in-operando
+synchrotron x-ray transmission nanoscale spectromicroscopy using an
+ultra-sensitive time-multiplexed technique. We observed only spatially uniform
+material changes during cell operation, in sharp contrast to the frequently
+detected formation of a localized conduction channel in transition-metal-oxide
+memristors. We also associated the response of assigned spectral features
+distinctly to non-volatile storage (resistance change) and writing of
+information (application of voltage and Joule heating). These results provide
+critical insights into high-performance memristors that will aid in device
+design, scaling and predictive circuit-modeling, all of which are essential for
+the widespread deployment of successful memristor applications.",1701.01784v1
+2017-01-19,Comparative study of LaNiO$_3$/LaAlO$_3$ heterostructures grown by pulsed laser deposition and oxide molecular beam epitaxy,"Variations in growth conditions associated with different deposition
+techniques can greatly affect the phase stability and defect structure of
+complex oxide heterostructures. We synthesized superlattices of the
+paramagnetic metal LaNiO3 and the large band gap insulator LaAlO3 by atomic
+layer-by-layer molecular beam epitaxy (MBE) and pulsed laser deposition (PLD)
+and compared their crystallinity, microstructure as revealed by high-resolution
+transmission electron microscopy images and resistivity. The MBE samples show a
+higher density of stacking faults, but smoother interfaces and generally higher
+electrical conductivity. Our study identifies the opportunities and challenges
+of MBE and PLD growth and serves as a general guide for the choice of
+deposition technique for perovskite oxides.",1701.05366v1
+2017-04-12,"Thermopower modulation clarification of the intrinsic effective mass in a transparent oxide semiconductor, BaSnO3","Although there are so many reports on the carrier effective mass (m*) of a
+transparent oxide semiconductor BaSnO3, it is almost impossible to know the
+intrinsic m* value because the reported m* values are scattered from 0.06 to
+3.7 m0. Here we successfully clarified the intrinsic m* of BaSnO3, m*=0.40 0.01
+m0, by the thermopower modulation clarification method. We also found the
+threshold of degenerate/non-degenerate semiconductor of BaSnO3; At the
+threshold, the thermopower value of both La-doped BaSnO3 and BaSnO3 TFT
+structure was 240 microvolt k-1, bulk carrier concentration was 1.4E19 cm-3,
+and two-dimensional sheet carrier concentration was 1.8E12 cm-2. When the EF
+locates above the parabolic shaped conduction band bottom, rather high mobility
+was observed. On the contrary, very low carrier mobility was observed when the
+EF lays below the threshold, most likely due to that the tail states suppress
+the carrier mobility. The present results are useful for further development of
+BaSnO3 based oxide electronics.",1704.03653v1
+2018-05-11,Statistical-Raman-Microscopy and Atomic-Force-Microscopy on Heterogeneous Graphene Obtained after Reduction of Graphene Oxide,"Graphene oxide can be used as a precursor to graphene but the quality of
+graphene flakes is highly heterogeneous. Scanning-Raman-Microscopy (SRM) is
+used to characterize films of graphene derived from flakes of graphene oxide
+with an almost intact carbon framework (ai-GO). The defect density of these
+flakes is visualized in detail by analyzing the intensity and full-width at
+half-maximum of the most pronounced Raman peaks. In addition, we superimpose
+the SRM results with AFM images and correlate the spectroscopic results with
+the morphology. Furthermore, we use SRM technique to display the amount of
+defects in a film of graphene. Thus, an area of 250 x 250 {\my}m2 of graphene
+is probed with a step-size increment of 1 {\mu}m. We are able to visualize the
+position of graphene flakes, edges and the substrate. Finally, we alter
+parameters of measurement to analyze the quality of graphene fast and reliable.
+The described method can be used to probe and visualize the quality of graphene
+films.",1805.04248v1
+2009-12-20,The Effected Oxide Capacitor in CMOS Structure of Integrated Circuit Level 5 Micrometer Technology,"This article is present the effected oxide capacitor in CMOS structure of
+integrated circuit level 5 micrometer technology. It has designed and basic
+structure of MOS diode. It establish with aluminum metallization layer by
+sputtering method, oxide insulator layer mode from silicon dioxide, n+ and p+
+semiconductor layer, it has high capacitance concentrate. From the MOS diode
+structure silicon dioxide thickness 0.5 micrometer, it will get capacitance
+between aluminum metal layer and p+ semiconductor at 28.62 pF, the capacitance
+between aluminum metal layer and n+ semiconductor at 29.55 pF. In this article
+establish second metal layer for measurement density values of first aluminum
+metal layer with second aluminum metal layer, it has density values at 16 pF.",0912.3971v1
+2011-11-18,"Structural and electronic properties of ScnOm (n=1~3, m=1~2n) clusters: Theoretical study using screened hybrid density functional theory","The structural and electronic properties of small scandium oxide clusters
+ScnOm (n = 1 - 3, m = 1 - 2n) are systematically studied within the screened
+hybrid density functional theory. It is found that the ground states of these
+scandium oxide clusters can be obtained by the sequential oxidation of small
+""core"" scandium clusters. The fragmentation analysis demonstrates that the ScO,
+Sc2O2, Sc2O3, Sc3O3, and Sc3O4 clusters are especially stable. Strong
+hybridizations between O-2p and Sc-3d orbitals are found to be the most
+significant character around the Fermi level. In comparison with standard
+density functional theory calculations, we find that the screened hybrid
+density functional theory can correct the wrong symmetries and yield more
+precise description for the localized 3d electronic states of scandium.",1111.4294v1
+2012-01-16,The role of non-local exchange in the electronic structure of correlated oxides,"We present a systematic study of the electronic structure of several
+prototypical correlated transition-metal oxides: VO2, V2O3, Ti2O3, LaTiO3, and
+YTiO3. In all these materials, in the low-temperature insulating phases the
+local and semilocal density approximations (LDA and GGA) of density-functional
+theory yield a metallic Kohn-Sham band structure. Here we show that, without
+invoking strong-correlation effects, the role of non-local exchange is
+essential to cure the LDA/GGA delocalization error and provide a band-structure
+description of the electronic properties in qualitative agreement with the
+experimental photoemission results. To this end, we make use of hybrid
+functionals that mix a portion of non-local Fock exchange with the local LDA
+exchange-correlation potential. Finally, we discuss the advantages and the
+shortcomings of using hybrid functionals for correlated transition-metal
+oxides.",1201.3308v1
+2012-04-01,Gated Conductance of Thin Indium Tin Oxide - The Simplest Transistor,"Transistors are the fundamental building block of modern electronic devices.
+So far, all transistors are based on various types of semiconductor junctions.
+The most common bipolar-junction transistors and metal-oxide-semiconductor
+field-effect transistors contain p-n junctions to control the current,
+depending on applied biases across the junctions. Thin-film transistors need
+metal-semiconductor junctions for injecting and extracting electrons from their
+channels. Here, by coating a heavily-doped thin indium-tin-oxide (ITO) film
+through a shadow mask onto a biopolymer chitosan/ITO/glass substrate, we can
+have a high-performance junctionless transparent organic-inorganic hybrid thin
+film transistor. This could be the simplest transistor in the world, to our
+knowledge, not only in its structure, but also its fabrication process. In
+addition, the device performance is found to be greatly enhanced using a
+reinforced chitosan/SiO2 hybrid bilayer dielectric stack. Our results clearly
+show that this architecture can lead to a new class of low-cost transistors.",1204.0169v1
+2012-04-09,Reduced graphene oxide as ultra fast temperature sensor,"We demonstrate the excellent temperature sensing property of a chemically
+synthesized reduced graphene oxide (rGO). It is found that with increase in
+temperature from 80 to 375K, the resistivity of reduced graphene oxide
+monotonically decreases. The ultra-fast temperature sensing property is
+demonstrated by keeping and removing a block of ice under the rGO sensor, which
+shows the resistance of rGO increases by 15% in 592 miliseconds and recovers in
+8.92 seconds. The temperature sensing of rGO is compared with a standard
+platinum thermo sensor (Pt 111) and found the sensitivity is much better in
+rGO.",1204.1928v2
+2012-04-16,Complementary Resistive Switching in Tantalum Oxide-Based Resistive Memory Devices,"Complementary resistive switches (CRS) are considered as a potential solution
+for the sneak path problem in large-scale integration of passive crossbar
+resistive memory arrays. A typical CRS is composed of two bipolar memory cells
+that are connected anti-serially. Here we report a tantalum-oxide based
+resistive memory that achieves the complementary switching functionality within
+a single memory cell. The complementary switching effect is accompanied by
+switching polarity reversal in different voltage bias regimes. These effects
+were explained by the redistribution of oxygen vacancies inside the
+tantalum-oxide layers. The effects of symmetry breaking on bipolar switching
+and complementary switching were also discussed.",1204.3515v2
+2013-09-19,High-throughput synthesis of thermoelectric Ca$_3$Co$_4$O$_9$ films,"Properties of complex oxide thin films can be tuned over a range of values as
+a function of mismatch, composition, orientation, and structure. Here, we
+report a strategy for growing structured epitaxial thermoelectric thin films
+leading to improved Seebeck coefficient. Instead of using single-crystal
+sapphire substrates to support epitaxial growth, Ca$_3$Co$_4$O$_9$ films are
+deposited, using the Pulsed Laser Deposition technique, onto Al$_2$O$_3$
+polycrystalline substrates textured by Spark Plasma Sintering. The structural
+quality of the 2000 \AA thin film was investigated by Transmission Electron
+Microscopy, while the crystallographic orientation of the grains and the
+epitaxial relationships were determined by Electron Back Scatter Diffraction.
+The use of a polycrystalline ceramic template leads to structured films that
+are in good local epitaxial registry. The Seebeck coefficient is about 170
+$\mu$V/K at 300 K, a typical value of misfit material with low carrier density.
+This high-throughput process, called combinatorial substrate epitaxy, appears
+to facilitate the rational tuning of functional oxide films, opening a route to
+the epitaxial synthesis of high quality complex oxides.",1309.4885v1
+2013-09-20,Effects of dopants in InOx-based amorphous oxide semiconductors for thin-film transistor applications,"Amorphous metal oxide thin-film transistors (TFT) are fabricated using
+InOx-based semiconductors doped with TiO2, WO3 or SiO2. Although density of
+dopant is low in the film, change in the electrical properties showed strong
+dependence on the dopant species. We found that the dependence could be
+reasonably explained by the bond-dissociation energy. By incorporating the
+dopant with higher bond-dissociation energy, the film becomes less sensitive to
+oxygen partial pressure used during sputtering deposition and remains
+electrically stable to thermal annealing treatment. The concept of
+bond-dissociation energy can contribute to the realization of more stable metal
+oxide TFTs for flat panel displays.",1309.5183v1
+2014-05-02,Unusual synchronization phenomena during electrodissolution of silicon: the role of nonlinear global coupling,"The photoelectrodissolution of n-type silicon constitutes a convenient model
+system to study the nonlinear dynamics of oscillatory media. On the silicon
+surface, a silicon oxide layer forms. In the lateral direction, the thickness
+of this layer is not uniform. Rather, several spatio-temporal patterns in the
+oxide layer emerge spontaneously, ranging from cluster patterns and turbulence
+to quite peculiar dynamics like chimera states. Introducing a nonlinear global
+coupling in the complex Ginzburg-Landau equation allows us to identify this
+nonlinear coupling as the essential ingredient to describe the patterns found
+in the experiments. The nonlinear global coupling is designed in such a way, as
+to capture an important, experimentally observed feature: the spatially
+averaged oxide-layer thickness shows nearly harmonic oscillations. Simulations
+of the modified complex Ginzburg-Landau equation capture the experimental
+dynamics very well.",1405.0414v1
+2016-07-30,Environmental Instability and Degradation of Single- and Few-Layer WTe2 Nanosheets in Ambient Conditions,"Since the discovery of large, non-saturating magnetoresistance in bulk WTe2
+which allows microexfoliation, single- and few-layer WTe2 crystals have
+attracted increasing interests. However, as it mentioned in existing studies,
+WTe2 flakes appear to degrade in ambient conditions. Here we report
+experimental observations of saturating degradation in few-layer WTe2 through
+Raman spectroscopy characterization and careful monitoring of the degradation
+of single-, bi- and tri-layer (1L, 2L & 3L) WTe2 over long time. Raman peak
+intensity decreases during WTe2 degradation and 1L flakes degrade faster than
+2L and 3L flakes. The relatively faster degradation in 1L WTe2 could be
+attributed to low energy barrier of oxygen reaction with WTe2. We further
+investigate the degradation mechanisms of WTe2 using XPS and AES and find that
+oxidation of Te and W atoms is the main reason of WTe2 degradation. In
+addition, we observe oxidation occurs only in the depth of 0.5nm near the
+surface, and the oxidized WTe2 surface could help prevent inner layers from
+further degradation.",1608.00097v2
+2016-08-01,Growth and engineering of perovskite SrIrO3 thin films,"5d transition-metal-based oxides display emergent phenomena due to the
+competition between the relevant energy scales of the correlation, bandwidth,
+and most importantly, the strong spin-orbit coupling (SOC). Starting from the
+prediction of novel oxide topological insulators in bilayer ABO3 (B = 5d
+elements) thin-film grown along the (111) direction, 5d-based perovskites (Pv)
+form a new paradigm in the thin-film community. Here, we reviewed the
+scientific accomplishments in Pv-SrIrO3 thin films, a popular candidate for
+observing non-trivial topological phenomena. Although the predicted topological
+phenomena are unknown, the Pv-SrIrO3 thin film shows many emergent properties
+due to the delicate interplay between its various degrees of freedom. These
+observations provide new physical insight and encourage further research on the
+design of new 5d-based heterostructures or superlattices for the observation of
+the hidden topological quantum phenomena in strong spin-orbit coupled oxides.",1608.00482v2
+2016-08-08,Observation of field emission from GeSn nanoparticles epitaxially grown on silicon nanopillar arrays,"We apply molecular beam epitaxy to grow GeSn-nanoparticles on top of
+Si-nanopillars patterned onto p-type Si wafers. We use X-ray photoelectron
+spectroscopy to confirm a metallic behavior of the nanoparticle surface due to
+partial Sn segregation as well as the presence of a superficial Ge oxide. We
+report the observation of stable field emission current from the
+GeSn-nanoparticles. We prove that field emission can be enhanced by preventing
+GeSn nanoparticles oxidation or by breaking the oxide layer through electrical
+stress. Finally, we show that GeSn/p-Si junctions have a rectifying behavior.",1608.02511v1
+2016-08-16,On the origin of field-like spin-orbit torques in heavy metal-ferromagnet-oxide thin film heterostructures,"We report measurements of the thickness and temperature (T) dependencies of
+current-induced spin-orbit torques, especially the field-like (FL) component,
+in various heavy metal (HM)/normal metal (NM) spacer/ferromagnet (FM)/Oxide
+(MgO and HfOx/MgO) heterostructures. The FL torque in these samples originates
+from spin current generated by the spin Hall effect (SHE) in the HM. For a FM
+layer sufficiently thin that a substantial portion of this spin current can
+reach the FM/Oxide interface, T-dependent spin scattering there can yield a
+strong FL torque that is, in some cases, opposite in sign to that exerted at
+the NM/FM interface.",1608.04443v1
+2016-12-01,Dimethylsilanone generation from pyrolysis of polysiloxanes filled with nanosized silica and ceria/silica,"Polydimethylsiloxane (PDMS) is a widely used organosilicon polymer often
+employed in formulations with fine oxide particles for various high temperature
+applications. Although PDMS is considered to be thermally stable and chemically
+inert, it is not always clear how the oxide filler influences its
+thermoresistance, decomposition chemistry and what reactive products are formed
+in the underlying thermal reactions. In this work we use temperature programmed
+desorption mass spectrometry (TPD MS) to study the pyrolysis of PDMS and its
+composites with nanosized silica and ceria/silica. Our results suggest that the
+elusive organosilicon compound - dimethylsilanone is generated from PDMS over a
+broad temperature range (in some cases starting at 70${\deg}$C). The presence
+of nano-oxides catalyzed this process. Ions characteristic of the fragmentation
+of dimethylsilanone under electron ionization were assigned with the aid of DFT
+structure calculations. Possible reaction mechanisms for generating
+dimethylsilanone were discussed in the context of the calculated kinetic
+parameters. Observed accompanying products of PDMS pyrolysis, such as
+tetramethylcyclodisiloxane and hexamethylcyclotrisiloxane, indicate that
+multiple channels are involved in the dimethylsilanone release.",1612.00223v1
+2016-12-26,Semi-Dirac Semimetal in Silicene Oxide,"Semi-Dirac semimetal is a material exhibiting linear band dispersion in one
+direction and quadratic band dispersion in the orthogonal direction and,
+therefore, hosts massless and massive fermions at the same point in the
+momentum space. While a number of interesting physical properties have been
+predicted in semi-Dirac semimetals, it has been rare to realize such materials
+in condensed matters. Based on the fact that some honeycomb materials are
+easily oxidized or chemically absorb other atoms, here, we theoretically
+propose an approach of modifying their band structures by covalent addition of
+group-VI elements and strain engineering. We predict a silicene oxide with
+chemical formula of Si2O to be a candidate of semi-Dirac semimetal. Our
+approach is backed by the analysis and understanding of the effect of p-orbital
+frustration on the band structure of the graphene-like materials.",1612.08458v1
+2017-06-16,Heterogeneous nucleation of pits via step pinning during Si(100) homoepitaxy,"Using scanning tunneling microscopy (STM), we investigate oxide-induced
+growth pits in Si thin films deposited by molecular beam epitaxy. In the
+transition temperature range from 2D adatom islanding to step-flow growth,
+systematic controlled air leaks into the growth chamber induce pits in the
+growth surface. We show that pits are also correlated with oxygen-contaminated
+flux from Si sublimation sources. From a thermodynamic standpoint, multilayer
+growth pits are unexpected in relaxed homoepitaxial growth, whereas oxidation
+is a known cause for step pinning, roughening, and faceting on elemental
+surfaces, both with and without growth flux. Not surprisingly, pits are
+thermodynamically metastable and heal by annealing to recover a smooth periodic
+step arrangement. STM reveals new details about the pits' atomistic origins and
+growth dynamics. We give a model for heterogeneous nucleation of pits by
+preferential adsorption of {\AA}-sized oxide nuclei at intrinsic growth
+antiphase boundaries, and subsequent step pinning and bunching around the
+nuclei.",1706.05127v1
+2017-06-22,Theory of the spin galvanic effect at oxide interfaces,"The spin galvanic effect (SGE) describes the conversion of a non-equilibrium
+spin polarization into a transverse charge current. Recent experiments have
+demonstrated a large conversion efficiency for the two-dimensional electron gas
+formed at the interface between two insulating oxides, LaAlO$_3$ and SrTiO$_3$.
+Here we analyze the SGE for oxide interfaces within a three-band model for the
+Ti t$_{2g}$ orbitals which displays an interesting variety of effective
+spin-orbit couplings in the individual bands that contribute differently to the
+spin-charge conversion. Our analytical approach is supplemented by a numerical
+treatment where we also investigate the influence of disorder and temperature,
+which turns out to be crucial to provide an appropriate description of the
+experimental data.",1706.07243v1
+2017-07-31,Transparent perovskite barium stannate with high electron mobility and thermal stability,"Transparent conducting oxides (TCOs) and transparent oxide semiconductors
+(TOSs) have become necessary materials for a variety of applications in the
+information and energy technologies, ranging from transparent electrodes to
+active electronics components. Perovskite barium stannate (BaSnO3), a new TCO
+or TOS system, is a potential platform for realizing optoelectronic devices and
+observing novel electronic quantum states due to its high electron mobility,
+excellent thermal stability, high transparency, structural versatility, and
+flexible doping controllability at room temperature. This article reviews
+recent progress in the doped BaSnO3 system, discussing the wide physical
+properties, electron-scattering mechanism, and demonstration of key
+semiconducting devices such as pn diodes and field-effect transistors.
+Moreover, we discuss the pathways to achieving two-dimensional electron gases
+at the interface between BaSnO3 and other perovskite oxides and describe
+remaining challenges for observing novel quantum phenomena at the
+heterointerface.",1707.09778v1
+2017-10-11,Solution Monolayer Epitaxy for Tunable Atomically Sharp Oxide Interfaces,"Epitaxial growth of atomically-sharp interfaces serves as one of the main
+building blocks of nanofabrication. Such interfaces are crucial for the
+operation of various devices including transistors, photo-voltaic cells, and
+memory components. In order to avoid charge traps that may hamper the operation
+of such devices, it is critical for the layers to be atomically-sharp.
+Fabrication of atomically sharp interfaces normally requires ultra-high vacuum
+techniques and high substrate temperatures. We present here a new self-limiting
+wet chemical process for deposition of epitaxial layers from alkoxide
+precursors. This method is fast, cheap, and yields perfect interfaces as we
+validate by various analysis techniques. It allows the design of
+heterostructures with half-unit cell resolution. We demonstrate our method by
+designing hole-type oxide interfaces SrTiO3/BaO/LaAlO3. We show that transport
+through this interface exhibits properties of mixed electron-hole contributions
+with hole mobility exceeding that of electrons. Our method and results are an
+important step forward towards a controllable design of a p-type oxide
+interface.",1710.04216v1
+2017-10-17,Unified mechanism of the surface Fermi level pinning in III-As nanowires,"Fermi level pinning at the oxidized (110) surfaces of III-As nanowires (GaAs,
+InAs, InGaAs, AlGaAs) is studied. Using scanning gradient Kelvin probe
+microscopy, we show that the Fermi level at oxidized cleavage surfaces of
+ternary Al$_{x}$Ga$_{1-x}$As (0$\le$x$\le$0.45) and Ga$_{x}$In$_{1-x}$As
+(0$\le$x$\le$1) alloys is pinned at the same position of 4.8$\pm$0.1 eV with
+regard to the vacuum level. The finding implies a unified mechanism of the
+Fermi level pinning for such surfaces. Further investigation, performed by
+Raman scattering and photoluminescence spectroscopy, shows that photooxidation
+of the Al$_{x}$Ga$_{1-x}$As and Ga$_{x}$In$_{1-x}$As nanowires leads to the
+accumulation of an excess arsenic on their crystal surfaces which is
+accompanied by a strong decrease of the band-edge photoluminescence intensity.
+We conclude that the surface excess arsenic in crystalline or amorphous forms
+is responsible for the Fermi level pinning at oxidized (110) surfaces of III-As
+nanowires.",1710.06227v2
+2017-10-23,Scavenging of oxygen vacancies at modulation-doped oxide interfaces: Evidence from oxygen isotope tracing,"The introduction of manganite buffer layers, La7/8Sr1/8MnO3 (LSMO) in
+particular, at the metallic interface between SrTiO3 (STO) and another band
+insulator suppresses the carrier density of the interfacial two-dimensional
+electron gas (2DEG) and improves significantly the electron mobility. However,
+the mechanisms underlying the extreme mobility enhancement remain elusive.
+Herein, we used 18O isotope exchanged SrTi18O3 as substrates to create 2DEG at
+room temperature with and without the LSMO buffer layer. By mapping the oxygen
+profile across the interface between STO18 and disordered LaAlO3 or
+yttria-stabilized zirconia (YSZ), we provide unambiguous evidence that redox
+reactions occur at oxide interfaces even grown at room temperature. Moreover,
+the manganite buffer layer not only suppresses the carrier density but also
+strongly suppresses the oxygen exchange dynamics of the STO substrate, which
+likely prevents the reduction of STO during the formation of the 2DEG. The
+underlying mechanism on the enhanced electron mobility at buffered oxide
+interfaces is also discussed.",1710.08118v1
+2017-10-25,Theoretical Investigation of Li and Na Oxides Adsorption on TiC(111) Surface for Metal-Air Rechargeable Batteries,"We analyze, with Density Functional Theory (DFT) calculations, the adsorption
+energies of Li$_2$O$_2$, Na$_2$O$_2$ and NaO$_2$ on clean and oxygen passivated
+TiC (111) surfaces. We show, that after deposition of two molecular layers of
+alkali metal oxides, the initial state of the TiC surface becomes unimportant
+for the adsorption energy and that all adsorption energies approach their
+native crystal values. The structure of the adsorbed molecular layers is
+analyzed and compared to their native oxide crystal structure. Finally, we
+discuss the possible implications for electrode optimization for Li-air and
+Na-air batteries.",1710.09463v1
+2017-10-26,Thermally and Electrically Conductive Nanopapers from Reduced Graphene Oxide: effect of nanoflakes thermal annealing on the film structure and properties,"In this study, we report a different strategy to prepare graphene nanopapers
+from direct vacuum filtration. Instead of the conventional method, i.e. thermal
+annealing nanopapers at extremely high temperatures prepared from graphene
+oxide (GO) or partially reduced GO, we fabricate our graphene nanopapers
+directly from suspensions of fully reduced graphene oxide (RGO), obtained after
+RGO and thermally annealing at 1700 {\deg}C in vacuum. By using this approach,
+we studied the effect of thermal annealing on the physical properties of the
+macroscopic graphene-based papers. Indeed, we demonstrated that the enhancement
+of the thermal and electrical properties of graphene nanopapers prepared from
+annealed RGO is strongly influenced by the absence of oxygen functionalities
+and the morphology of the nanoflakes. Hence, our methodology can be considered
+as a valid alternative to the classical approach.",1710.09665v1
+2017-10-29,Synthesis of high-oxidation Y-Ba-Cu-O phases in superoxygenated thin films,"It is known that solid-state reaction in high-pressure oxygen can stabilize
+high-oxidation phases of Y-Ba-Cu-O superconductors in powder form. We extend
+this superoxygenation concept of synthesis to thin films which, due to their
+large surface-to-volume ratio, are more reactive thermodynamically. Epitaxial
+thin films of $\rm{YBa_2Cu_3O_{7-\delta}}$ grown by pulsed laser deposition are
+annealed at up to 700 atm O$_2$ and 900$^\circ$C, in conjunction with Cu
+enrichment by solid-state diffusion. The films show clear formation of
+$\rm{Y_2Ba_4Cu_7O_{15-\delta}}$ and $\rm{Y_2Ba_4Cu_8O_{16}}$ as well as regions
+of $\rm{YBa_2Cu_5O_{9-\delta}}$ and YBa$_2$Cu$_6$O$_{10-\delta}$ phases,
+according to scanning transmission electron microscopy, x-ray diffraction and
+x-ray absorption spectroscopy. Similarly annealed $\rm{YBa_2Cu_3O_{7-\delta}}$
+powders show no phase conversion. Our results demonstrate a novel route of
+synthesis towards discovering more complex phases of cuprates and other
+superconducting oxides.",1710.10672v2
+2017-12-11,Pyrochlore Oxide Superconductor Cd2Re2O7 Revisited,"The superconducting pyrochlore oxide Cd2Re2O7 is revisited with a particular
+emphasis on the sample-quality issue. The compound has drawn attention as the
+only superconductor (Tc = 1.0 K) that has been found in the family of
+{\alpha}-pyrochlore oxides since its discovery in 2001. Moreover, it exhibits
+two characteristic structural transitions from the cubic pyrochlore structure,
+with the inversion symmetry broken at the first one at 200 K. Recently, it has
+attracted increasing attention as a candidate spin-orbit coupled metal (SOCM),
+in which specific Fermi liquid instability is expected to lead to an odd-parity
+order with spontaneous inversion-symmetry breaking [L. Fu, Phys. Rev. Lett.
+115, 026401 (2015)] and parity-mixing superconductivity [V. Kozii and L. Fu:
+Phys. Rev. Lett. 115 (2015) 207002; Y. Wang et al., Phys. Rev. B 93 (2016)
+134512]. We review our previous experimental results in comparison with those
+of other groups in the light of the theoretical prediction of the SOCM, which
+we consider meaningful and helpful for future progress in understanding this
+unique compound.",1712.03617v1
+2017-11-21,Three-dimensional printed Yttria-stabilized Zirconia self-supported electrolytes for Solid Oxide Fuel Cell applications,"Additive manufacturing represents a revolution due to its unique capabilities
+for freeform fabrication of near net shapes with strong reduction of waste
+material and capital cost. These unfair advantages are especially relevant for
+expensive and energy-demanding manufacturing processes of advanced ceramics
+such as Yttria-stabilized Zirconia, the state-of-the-art electrolyte in Solid
+Oxide Fuel Cell applications. In this study, self-supported electrolytes of
+yttria-stabilized zirconia have been printed by using a stereolithography
+three-dimensional printer. Printed electrolytes and complete cells fabricated
+with cathode and anode layers of lanthanum strontium manganite- and nickel
+oxide-yttria-stabilized zirconia composites, respectively, were electrochemical
+characterized showing full functionality. In addition, more complex
+configurations of the electrolyte have been printed yielding an increase of the
+performance entirely based on geometrical aspects. Complementary, a numerical
+model has been developed and validated as predictive tool for designing more
+advanced configurations that will enable highly performing and fully customized
+devices in the next future",1712.04036v1
+2018-01-16,Recent progress on the fabrication of silver nanowire-based transparent electrodes,"Transparent electrodes (TEs) made of metallic nanowires, such as Ag, Au, Cu,
+and Ni, have attracted rising attention for several reasons: 1) they can act as
+a substitute for tin oxide-based TEs such as indium-tin oxide (ITO) and
+fluorine-doped tin oxide (FTO); 2) various methods exist for fabricating such
+TEs such as filtration, spraying and meyer bar coating; 3) greater
+compatibility with different substrates can be achieved due to the variety of
+fabrication methods; and 4) extra functions in addition to serving as
+electrodes, such as catalytic abilities, can be obtained due to the metals that
+compose the TEs. There are a large number of applications for TEs, ranging from
+electronics and sensors to biomedical devices. This short review is a summary
+of recent progress, mainly during the past five years, on silver nanowire-based
+TEs. The focus of the review will be on theory development, mechanical,
+chemical and thermal stability and optical properties. The many applications of
+TEs are outside the scope of this review.",1801.05238v1
+2018-09-20,Effect of TCNQ layer cover on oxidation dynamics of black phosphorus,"The puckered surface of black phosphorus represents an ideal substrate for an
+unconventional arrangement of physisorbed species and the resulting specific
+two-dimensional chemistry of this system. This opens the way to investigate the
+chemical and physical properties of locally confined areas of black phosphorus
+without the necessity for further physical downscaling of the material. We have
+evaporated TCNQ on top of black phosphorus under over-saturation
+non-equilibrium conditions in vacuum. The evolution of linear density and
+height of droplets formed through oxidation during exposure to air was studied
+time-dependently by scanning-force microscopy. Our study suggests that the TCNQ
+molecules spontaneously arrange in a thin layer of the order of a few nm
+height, which, however, is fragmented with a periodicity of about 100 nm. It is
+shown that within the confined space separating the layer fragments the
+chemical dynamics of the oxidation process is remarkably different than on a
+bare black phosphorus surface.",1809.08915v1
+2018-09-30,Ultra-low Power Microwave Oscillators based on Phase Change Oxides as Solid-State Neurons,"Neuro-inspired computing architectures are one of the leading candidates to
+solve complex, large-scale associative learning problems. The two key building
+blocks for neuromorphic computing are the synapse and the neuron, which form
+the distributed computing and memory units. Solid state implementations of
+these units remain an active area of research. Specifically, voltage or current
+controlled oscillators are considered a minimal representation of neurons for
+hardware implementations. Such oscillators should demonstrate synchronization
+and coupling dynamics for demonstrating collective learning behavior, besides
+the desirable individual characteristics such as scaling, power, and
+performance. To this end, we propose the use of nanoscale, epitaxial
+heterostructures of phase change oxides and oxides with metallic conductivity
+as a fundamental unit of an ultralow power, tunable electrical oscillator
+capable of operating in the microwave regime. Our simulations show that
+optimized heterostructure design with low thermal boundary resistance can
+result in operation frequency of up to 3 GHz and power consumption as low as 15
+fJ/cycle with rich coupling dynamics between the oscillators.",1810.00454v1
+2018-10-01,"Quantified Degeneracy, Entropy and Metal-Insulator Transition in Complex Transition-Metal Oxides","Understanding complex correlated oxides and their phase transitions has long
+been a challenge. The difficulty largely arises from the intriguing interplay
+between multiple degrees of freedoms. While degeneracy can play an important
+role in determining material characteristics, there is no well-defined way to
+quantify and to unveil its role in real materials having complicated band
+structures. Here we suggest a way to quantify the `effective degeneracy'
+relevant to metal-insulator transition by introducing entropy-like terms. This
+new quantity well describes the electronic behaviors of transition-metal oxides
+as a function of external and internal parameters. With $3d$ titanates, $4d$
+ruthenates, and $5d$ iridates as our examples, we show that this new effective
+quantity provides useful insights to understand these systems and their phase
+transitions. For LaTiO$_3$/LaAlO$_3$ superlattice, we suggest a novel
+`degeneracy control' metal-insulator transition.",1810.00502v1
+2018-10-01,Synchrotron radiation based photoemission studies of indium oxide passivation of ZnO(0001) surface at high temperature,"Passivation of surface reactive ZnO(0001)-Zn terminated surface is carried
+out by in-situ deposition of indium metal and post deposition annealing at high
+temperature (600 C - 1000 C). After the every cycle of indium deposition and
+annealing the ZnO(0001) surface is characterised by synchrotron radiation based
+photoemission. The photoemission studies confirmed the formation of deposited
+indium turned into indium oxide (In2O3 and In2Ox) as surface passivation layer.
+The core level spectra for Zn, C, O, were acquired at different photon energy
+for high surface sensitivity. Overall core level peaks (Zn 3p, In 4d, O 1s)
+having average binding shift ranging from 0.5 eV to 0.8 eV. The valance band
+spectra shows fermi level shift of 0.9 eV after passivation at 1000 C and work
+function raises form 4.06 eV to 4.77 eV. Downward band bending of ZnO(0001)
+surface is turned into upward bending of 0.98 eV by indium oxide passivation at
+high temperature, which is suitable for making ZnO schotty contact and devices.",1810.00899v1
+2018-10-04,Electronic structure and properties of lithium-rich complex oxides,"Lithium-rich complex transition-metal oxides Li$_2$MoO$_3$, Li$_2$RuO$_3$,
+Li$_3$RuO$_4$, Li$_3$NbO$_4$, Li$_5$FeO$_4$, Li$_5$MnO$_4$ and their
+derivatives are of interest for high-capacity battery electrodes. Here, we
+report a first-principles density-functional theory study of the atomic and
+electronic structure of these materials using the Heyd-Scuseria-Ernzerhof (HSE)
+screened hybrid functional which treats all orbitals in the materials on equal
+footing. Dimerization of the transition-metal ions is found to occur in layered
+Li$_2$MoO$_3$, in both fully lithiated and partially delithiated compounds. The
+Ru--Ru dimerization does not occur in fully lithiated Li$_2$RuO$_3$, in
+contrast to what is commonly believed; Ru--Ru dimers are, however, found to
+occur in the presence of lithium vacancies caused by lithium loss during
+synthesis and/or lithium removal during use. We also analyze the electronic
+structure of the complex oxides and discuss the delithiation mechanism in these
+battery electrode materials.",1810.02039v1
+2018-10-08,Creation of oxide coating on Al 1050 alloy,"Plasma electrolytic oxidation (PEO) is a surface processing for oxide
+coatings formation with advanced properties. Mostly, PEO is performed in an
+aqueous solution electrolyte which limits the dimension of treated parts due to
+the system heating up. Therefore, treatment of large surfaces cannot be applied
+in aqueous electrolyte. In current work an alternative approach of PEO
+treatment applied in aluminum 1050 alloy in nitrate molten salt was
+investigated. The structure, phase and chemical compositions, and
+micro-hardness were examined using XRD, SEM, EDS and micro-hardness tests. The
+obtained results showed that formed coating contains from two phases of
+{\alpha}- Al2O3 and {\gamma}- Al2O3. It was found that formed coating is free
+of any contaminants originated from the electrolyte and has no damages, which
+are usually present in coatings formed in PEO treatment in aqueous solution
+electrolyte.",1810.03300v1
+2018-10-22,Strain-induced heteronuclear charge disproportionation in EuMnO$_3$,"Charge disproportionation transitions in complex oxides most commonly link
+high-temperature phases containing identical cations with the same oxidation
+state and crystallographic site, to low-temperature phases in which charge
+transfer between these ions results in unequal oxidation states. Here we
+propose, based on density functional calculations, a related concept that we
+term \textit{heteronuclear} charge disproportionation, in which charge transfer
+occurs between different elements on different crystallographic sites. We show
+for the case of EuMnO$_3$ that such a transition from the experimentally
+observed Eu$^{3+}$Mn$^{3+}$O$_3$ phase to the so far unknown
+Eu$^{2+}$Mn$^{4+}$O$_3$ phase can be triggered by pressure and epitaxial
+strain. We then identify measurable signatures to aid in an experimental
+exploration of the complex pressure- and biaxial strain-dependent phase
+stability of EuMnO$_3$ that we hope to motivate with our predictions. We
+suggest other candidate crystal chemistries for heteronuclear charge
+disproportionation, in which novel physics could emerge from the coexistence of
+instabilities.",1810.09204v1
+2018-10-22,First-principles studies of spin-orbital physics in pyrochlore oxides,"The pyrochlore oxides $A_2B_2$O$_7$ exhibit a complex interplay between
+geometrical frustration, electronic correlations, and spin-orbit coupling, due
+to the lattice structure and active charge, spin, and orbital degrees of
+freedom. Understanding the properties of these materials is a theoretical
+chalenge, because their intricate nature depends on material-specific details
+and quantum many-body effects. Here we review our recent studies based on
+first-principles calculations and quantum many-body theories for 4$d$ and 5$d$
+pyrochlore oxides with $B$=Mo, Os, and Ir. In these studies, the spin-orbit
+coupling and local electron correlations are treated within the LDA+$U$ and
+LDA+dynamical mean-field theory formalisms. We also discuss the technical
+aspects of these calculations.",1810.09596v2
+2018-10-24,Gold Nanoparticle Superlattice in Porous Silica and Low Temperature Catalytic CO Oxidation,"The practical use of nanoparticle superlattices (NPSLs) which are of great
+interest as materials with designed functionalities is often limited by their
+lack of structural stability under various utilization conditions. Here, we
+report a new method for directly synthesizing NPSL fully embedded in
+hierarchically porous silica which provides exceptional stability and efficient
+pathways for reactant molecules, making the NPSL highly efficient catalyst. The
+superlattices made of 12 nm gold nanoparticles exhibit exceptionally high
+catalytic activity for CO oxidation at low temperature, showing higher activity
+than that of small gold nanoparticles (ca. 3 nm) supported on metal oxides. The
+gold NPSL also shows unprecedented stability, maintaining its structural
+stability and catalytic activity without any signature of degradation over a
+month of continuous catalytic reaction, which present one significant step
+forward to realizing the great potentials of gold catalysts in automotive
+emission control and green chemistry industry.",1810.10228v2
+2019-06-29,Ultra-Low Surface Resistance via Vacuum Heat Treatment of Superconducting Radiofrequency Cavities,"We report on an effort to improve the performance of superconducting
+radiofrequency cavities by the use of heat treatment in a temperature range
+sufficient to dissociate the natural surface oxide. We find that the residual
+resistance is significantly decreased, and we find an unexpected reduction in
+the BCS resistance. Together these result in extremely high quality factor
+values at relatively large accelerating fields Eacc ~20 MV/m: Q0 of 3-4x10^11
+at <1.5 K and Q0 ~5x10^10 at 2.0 K. In one cavity, measurements of surface
+resistance versus temperature showed an extremely small residual resistance of
+just 0.63+/-0.06 nOhms at 16 MV/m. SIMS measurements confirm that the oxide was
+significantly dissociated, but they also show the presence of nitrogen after
+heat treatment. We also present studies of surface oxidation via exposure to
+air and to water, as well as the effects of very light surface removal via HF
+rinse. The possibilities for applications and the planned future development
+are discussed.",1907.00147v1
+2019-07-01,Stable structures and electronic properties of perovskite oxide monolayers,"It is highly desirable to search for promising two-dimensional (2D) monolayer
+materials for deep insight of 2D materials and applications. We use
+first-principles method to investigate tetragonal perovskite oxide monolayers
+as 2D materials. We find four stable 2D monolayer materials from SrTiO$_3$,
+LaAlO$_3$, KTaO$_3$, and BaFeO$_3$, denoting them as STO-ML, LAO-ML, KTO-ML,
+and BFO-ML. Our further study shows that through overcoming dangling bonds the
+first three monolayers are 2D wide-gap semiconducotors, and BFO-ML is a 2D
+isotropic Heisenberg ferromagnetic metal. There is a large electrostatic
+potential energy difference between the two sides, reflecting a large
+out-of-plane dipole, in each of the monolayers. These make a series of 2D
+monolayer materials, and should be useful in novel electronic devices
+considering emerging phenomena in perovskite oxide heterostructures.",1907.00898v2
+2019-07-19,Tunable coupling and isolation of single electrons in silicon metal-oxide-semiconductor quantum dots,"Extremely long coherence times, excellent single-qubit gate fidelities and
+two-qubit logic have been demonstrated with silicon metal-oxide-semiconductor
+spin qubits, making it one of the leading platforms for quantum information
+processing. Despite this, a long-standing challenge in this system has been the
+demonstration of tunable tunnel coupling between single electrons. Here we
+overcome this hurdle with gate-defined quantum dots and show couplings that can
+be tuned on and off for quantum operations. We use charge sensing to
+discriminate between the (2,0) and (1,1) charge states of a double quantum dot
+and show excellent charge sensitivity. We demonstrate tunable coupling up to 13
+GHz, obtained by fitting charge polarization lines, and tunable tunnel rates
+down to below 1 Hz, deduced from the random telegraph signal. The demonstration
+of tunable coupling between single electrons in a silicon
+metal-oxide-semiconductor device provides significant scope for high-fidelity
+two-qubit logic toward quantum information processing with standard
+manufacturing.",1907.08523v2
+2019-07-23,"Strain Tuning of Plasma Frequency in Vanadate, Niobate, and Molybdate Perovskite Oxides","A novel approach for finding new transparent conductors involves taking
+advantage of electronic correlations in metallic transition metal oxides, such
+as SrVO$_3$, to enhance the electronic effective mass and suppress the plasma
+frequency ($\omega_P$) to infrared. Success of this approach relies on finding
+a compound with the right electron effective mass and quasiparticle weight $Z$.
+Biaxial strain can in principle be a fruitful way to manipulate the electronic
+properties of materials to tune both of these quantities. In this study, we
+elucidate the behavior of the electronic properties of early transition metal
+oxides SrVO$_3$, SrNbO$_3$, and SrMoO$_3$ under strain, using first principles
+density functional theory and dynamical mean field theory. We show that strain
+is not an effective way to manipulate the plasma frequency, but dimensionality
+of the crystal structure and origin of electronic correlations strongly affect
+the trends in both $\omega_P$ and $Z$.",1907.09860v1
+2019-07-25,High Performance Fin-FET electrochemical sensor with high-k dielectric materials,"In this work we combine a Fin Field Effect Transistor (Fin-FET) characterised
+by a high height to width aspect ratio with high-k dielectric materials to
+study the optimized design for chemical-FETs to provide higher transconductance
+(and thus a better signal to noise ratio), increased dynamic range and chemical
+stability. We used pH sensing to verify the design. We explored the sensitivity
+and response linearity of silicon dioxide, alumina and hafnium oxide as
+dielectric materials sensing pH, and compared their chemical stability in
+different acids. The high aspect ratio fin geometry of the sensor provides high
+currents, as well as a planar conduction channel more reliable than traditional
+silicon nanowires. The hafnium oxide Fin-FET configuration performed the best
+delivering the most linear response both for the output and transfer
+characteristics providing a wider dynamic range. Hafnium oxide also showed the
+best chemical stability. Thus, we believe that the developed high aspect ratio
+Fin-FETs/high-k dielectric system can offer the best compromise of performance
+of FET-based sensors.",1907.11022v1
+2019-07-27,Microwave derived monoclinic Ba1-xSnxNb2O6 materials as an alternative of ITO,"Microwave synthesis was optimized for preparing novel monoclinic Tin-doped
+Barium Niobate ceramics (Ba1-xSnxNb2O6; x= 0.0, 0.01, 0.05, 0.1, 0.2, 0.3) BSN.
+The intensity of monoclinic phase formation was observed to decrease on
+increasing tin as dopant indicating decreased crystallinity. Strained
+crystalline phase was observed in undoped sample that became severe on doping
+tin. Monoclinic metal alloy Sn2O3 formation was confirmed on increasing tin
+doping beyond 5%. Electronic configuration of tin (II) oxide supports the local
+site-wise monoclinic disorder in crystal structure due to sterically active
+lone pair. Such a disorder arranges increased number of degenerate energy
+states and reduce effective energy gap between conduction band minimum and
+valence band maximum. All BSN compositions were investigated for monoclinic
+phase stabilization, ultra-violet absorption, dielectric response, raman modes
+and type of carrier concentration along with hall resistivity. All measurements
+possessed inflexion corresponding to 5 atomic % tin doping indicating
+successful site substitution and estimated Sn2O3 metal formation beyond this.
+The values of reducing optical energy band gap, transparency to visible
+spectrum and hall resistivity indicated utility of these materials as a
+substitute transparent conducting oxide (TCO) for well-known indium tin oxide
+(ITO).",1907.11946v1
+2019-07-29,Mechanical Characterisation of the Protective Al$_2$O$_3$ Scale in Cr$_2$AlC MAX phases,"MAX phases have great potential under demands of both high-temperature and
+high-stress performance, with their mixed atomic bonding producing the
+temperature and oxidation resistance of ceramics with the mechanical resilience
+of metals. Here, we measure the mechanical properties up to 980C by
+nanoindentation on highly dense and pure Cr$_2$AlC, as well as after oxidation
+with a burner rig at 1200C for more than 29 hours. Only modest reductions in
+both hardness and modulus up to 980C were observed, implying no change in
+deformation mechanism. Furthermore, micro-cantilever fracture tests were
+carried out at the Cr$_2$AlC/Cr$_7$C$_3$ and Cr$_7$C$_3$/Al$_2$O$_3$ interfaces
+after the oxidation of the Cr$_2$AlC substrates with said burner rig. The
+values are typical of ceramic-ceramic interfaces, below 4 MPa/m, leading to the
+hypothesis that the excellent macroscopic behaviour is due to a combination of
+low internal strain due to the match in thermal expansion coefficient as well
+as the convoluted interface.",1907.12341v1
+2019-09-03,Two-Dimensional Antimony Oxide,"Two-dimensional (2D) antimony, so-called antimonene, can form antimonene
+oxide when exposed to air. We present different types of single- and few-layer
+antimony oxide structures, based on density functional theory (DFT)
+calculations. Depending on stoichiometry and bonding type, these novel 2D
+layers have different structural stability and electronic properties, ranging
+from topological insulators to semiconductors with direct and indirect band
+gaps between 2.0 and 4.9 eV. We discuss their vibrational properties and Raman
+spectra for experimental identification of the predicted structures.",1909.01204v4
+2019-09-04,Structural and electronic phenomena at oxyfluoride KTaO$_3$/K$M$F$_3$ ($M$ = Zn and Ni) superlattices: Rashba splitting and 2DEG,"Here, we present the theoretical analysis of the structural and electronic
+degrees of freedom of two different oxide/fluoride perovskite superlattices,
+KTaO$_3$/KZnF$_3$ and KTaO$_3$/KNiF$_3$. Using first-principles calculations,
+we found the appearance of a two-dimensional electron, 2DEG, and hole, 2DHG,
+gases as a function of the number of layers of the different pristine
+materials. We demonstrate that the phonon-dynamics at the KTO/K$M$F
+superlattices play a crucial role in the appearance of these effects.
+Additionally, our results reveal a rather sizeable Rashba-type spin-splitting
+at these interfaces in comparison to another oxide/oxide counterparts.",1909.01921v1
+2019-09-09,High Dielectric Ternary Oxides from Crystal Structure Prediction and High-throughput Screening,"The development of new high dielectric materials is essential for advancement
+in modern electronics. Oxides are generally regarded as the most promising
+class of high dielectric materials for industrial applications as they possess
+both high dielectric constants and large band gaps. Most previous researches on
+high dielectrics were limited to already known materials. In this study, we
+conducted an extensive search for high dielectrics over a set of ternary oxides
+by combining crystal structure prediction and density functional perturbation
+theory calculations. From this search, we adopted multiple stage screening to
+identify 440 new low-energy high dielectric materials. Among these materials,
+33 were identified as potential high dielectrics favorable for modern device
+applications. Our research has opened an avenue to explore novel high
+dielectric materials by combining crystal structure prediction and high
+throughput screening.",1909.04195v1
+2019-09-17,Rational design principles for giant spin Hall effect in 5d-transition metal oxides,"Spin Hall effect (SHE), a mechanism by which materials convert a
+\textit{charge} current into a \textit{spin} current, invokes interesting
+physics and promises to empower transformative, energy-efficient memory
+technology. However, fundamental questions remain about the essential factors
+that determine SHE. Here we solve this open problem, presenting a comprehensive
+theory of five \textit{foundational factors} that control the value of
+intrinsic SHE in transition metal oxides. Arising from our key insight
+regarding the inherently geometric nature of SHE, we demonstrate that two of
+these factors are crystal field strength and structural distortions. Moreover,
+we discover that a new class of materials (anti-perovskites) promises to
+demonstrate \textit{giant} SHE, that is an order of magnitude larger than that
+reported for any oxide. We derive three other factors that control SHE and
+demonstrate the nuanced role of electron correlations. Our findings bring
+deeper insight into the physics driving SHE, and could help enhance, as well
+as, externally control SHE values.",1909.07544v2
+2019-09-18,Investigating the high-temperature thermoelectric properties of n-type rutile TiO$_2$,"Transition metal oxides are considered promising thermoelectric materials for
+harvesting high-temperature waste heat due to their stability, abundance and
+low toxicity. Despite their typically strong ionic character, they can exhibit
+surprisingly high power factors $\sigma S^2$, as in n-type SrTiO$_3$ for
+instance. Thus, it is worth examining other transition metal oxides that might
+surpass the performances of SrTiO$_3$. This theoretical paper investigates the
+thermoelectric properties of n-type rutile TiO$_2$, which is the most stable
+phase of titanium oxide up to 2000 K. The electronic structure is obtained
+through ab initio calculations, while the prominent features of strong
+electron-phonon interaction and defects states are modelled using a small
+number of parameters. The theoretical results are compared with a wealth of
+experimental data from the literature, yielding very good agreements over a
+wide range of carrier concentrations. This validates the hypothesis of band
+conduction in rutile TiO$_2$ and allows the prediction of the high-temperature
+thermoelectric properties.",1909.08554v2
+2019-10-08,Molecular Beam Epitaxy of lithium niobium oxide multifunctional materials,"The role of stoichiometry and growth temperature in the preferential
+nucleation of material phases in the Li-Nb-O family are explored yielding an
+empirical growth phase diagram. It is shown that while single parameter
+variation often produces multi-phase films, combining substrate temperature
+control with the previously published lithium flux limited growth allows the
+repeatable growth of high quality single crystalline films of many different
+oxide phases. Higher temperatures (800-1050 {\deg}C) than normally used in MBE
+were necessary to achieve high quality materials. At these temperatures the
+desorption of surface species is shown to play an important role in film
+composition. Using this method single phase films of NbO, NbO$_{2}$,
+LiNbO$_{2}$, Li$_{3}$NbO$_{4}$, LiNbO$_{3}$, and LiNb$_{3}$O$_{8}$ have been
+achieved in the same growth system, all on c-plane sapphire. Finally, the
+future of these films in functional oxide heterostructures is briefly
+discussed.",1910.03703v1
+2019-10-11,Fabrication of condense and thin YSZ electrolyte layer using novel thermal-assisted slurry spin coating method for IT-SOFC,"A simple spin coating approach is introduced to fabricate Yttria-Stabilized
+Zirconia (YSZ) electrolyte layer on NiO-YSZ anode substrate for solid oxide
+fuel cell applications. Heating the substrate during the slurry spin coating
+process enhances the affected area through the layer and leads to optimize the
+compacting amount of coated electrolyte particles before sintering procedure.
+On top of this bilayer substrate, LCFN is deposited as an intermediate
+temperature solid oxide fuel cell cathode, in order to have suitable output
+performances at intermediate temperature ranges. Applying humidified hydrogen
+as fuel and ambient air as the oxidant, cell performance characterizations
+exhibit higher power outputs for prepared sample. Electrochemical Impedance
+Spectroscopy measurements on single cells also demonstrate that both
+interfacial and Ohmic resistances are reduced. These results along with
+Scanning Electron Microscope micrographs reveal that the density of the YSZ
+layer which is coated by the suggested approach is better than the usual slurry
+spin coating method.",1910.05373v2
+2019-10-17,Substoichiometric ultrathin zirconia films cause strong metal-support interaction,"The strong metal-support interaction (SMSI) leads to substantial changes of
+the properties of an oxide-supported catalyst after annealing under reducing
+conditions. The common explanation is the formation of heavily reduced,
+ultrathin oxide films covering metal particles. This is typically encountered
+for reducible oxides such as TiO2 or Fe3O4. Zirconia (ZrO2), a typical catalyst
+support, is difficult to reduce and therefore no obvious candidate for the SMSI
+effect. In this work, we use inverse model systems with Rh(111), Pt(111), and
+Ru(0001) as supports. Contrary to expectations, we show that SMSI is
+encountered for zirconia. Upon annealing in ultra-high vacuum, oxygen-deficient
+ultrathin zirconia films ($\approx$ZrO$_{1.5}$) form on all three substrates.
+However, Zr remains in its preferred charge state of 4+, as electrons are
+transferred to the underlying metal. At high temperatures, the stability of the
+ultrathin zirconia films depends on whether alloying of Zr and the substrate
+metal occurs. The SMSI effect is reversible; the ultrathin suboxide films can
+be removed by annealing in oxygen.",1910.07798v1
+2019-10-28,Oxygen fugacities of extrasolar rocks: Evidence for an Earth-like geochemistry of exoplanets,"Oxygen fugacity is a measure of rock oxidation that influences planetary
+structure and evolution. Most rocky bodies in the Solar System formed at oxygen
+fugacities approximately five orders of magnitude higher than a hydrogen-rich
+gas of solar composition. It is unclear whether this oxidation of rocks in the
+Solar System is typical among other planetary systems. We exploit the elemental
+abundances observed in six white dwarfs polluted by the accretion of rocky
+bodies to determine the fraction of oxidized iron in those extrasolar rocky
+bodies and therefore their oxygen fugacities. The results are consistent with
+the oxygen fugacities of Earth, Mars, and typical asteroids in the Solar
+System, suggesting that at least some rocky exoplanets are geophysically and
+geochemically similar to Earth.",1910.12989v1
+2020-01-04,Which glass stability parameters can assess the glass-forming ability of oxide systems?,"Glass forming ability (GFA) is a property of utmost importance in glass
+science and technology. In this paper, we used a statistical
+methodology---involving bootstrap sampling and the Wilcoxon test---to find out
+which glass stability parameters can better predict the glass forming ability.
+We collected or measured the necessary data for twelve stoichiometric oxide
+glasses that underwent predominant heterogeneous nucleation (the most common
+case). We found that some GS parameters could predict the GFA of these oxide
+glasses quite well, whereas others perform poorly. Parameter $K_w$ was the top
+ranked, closely followed by the $K_H$, $\gamma$, $H^{'}$, $\Delta T_{rg}$, and
+$K_{cr}$. Our results corroborate previous reports carried out using a smaller
+number of glasses, much less GS parameters, and less rigorous statistics. We
+also found that using $T_c$ instead of $T_x$ improved the predictive power of
+these parameters. Finally, the Jezica, the only parameter considered here that
+predicts the GFA without requiring the production of a glass piece (i.e.,
+without relying on any crystallization information), ranked reasonably well in
+our analysis.",2001.01113v1
+2020-01-08,Electronic model of a volcano-shaped size dependence in CO oxidation by gold nanoparticles,"The theoretical model of a volcano-type size dependence of extraordinary
+catalytic activity of gold nanoparticles in CO oxidation is proposed based on
+the electronic theory of catalysis, the jellium model of metal clusters and the
+d-band model of formation bonds in transition metals. The kinetics of the
+general mechanism of CO oxidation reaction catalyzed by gold nanoparticles
+through dissociative adsorption of oxygen molecules and interaction with CO
+molecules from the gas-phase is considered by introducing electronic steps into
+3-step mechanism of the reaction, corresponding to transitions between weak and
+strong chemisorbed states of intermediates. By introducing the exponential
+dependences of the fractions of weak and strong chemisorbed intermediates (O,
+CO2) on the size dependent Fermi level of the metal cluster with respect to
+antibonding energy levels of the intermediates, a volcano-type dependence of
+reaction rate on the size of gold nanoparticles is obtained. The dependence of
+the reaction rate upon the supports is taken into account by introducing the
+additional energy term into the Fermi level of the metal catalyst.",2001.02647v1
+2020-01-08,Vanadium oxide thin films and fibers obtained by acetylacetonate sol-gel method,"Vanadium oxide films and fibers have been fabricated by the acetylacetonate
+sol-gel method followed by annealing in wet nitrogen. The samples are
+characterized by X-ray diffraction and electrical conductivity measurements.
+The effects of a sol aging, the precursor decomposition and the gas atmosphere
+composition on the annealing process, structure and properties of the films are
+discussed. The two-stage temperature regime of annealing of amorphous films in
+wet nitrogen for formation of the well crystallized VO2 phase is chosen: 1)
+25-550 C and 2) 550-600 C. The obtained films demonstrate the metal-insulator
+transition and electrical switching. Also, the effect of the
+polyvinylpyrrolidone additive concentration and electrospinning parameters on
+qualitative (absence of defects and gel drops) and quantitative (length and
+diameter) characteristics of vanadium oxide fibers is studied.",2001.11329v1
+2020-02-24,Coupling lattice instabilities across the interface in ultrathin oxide heterostructures,"Oxide heterointerfaces constitute a rich platform for realizing novel
+functionalities in condensed matter. A key aspect is the strong link between
+structural and electronic properties, which can be modified by interfacing
+materials with distinct lattice symmetries. Here we determine the effect of the
+cubic-tetragonal distortion of $\text{SrTiO}_3$ on the electronic properties of
+thin films of $\text{SrIrO}_3$, a topological crystalline metal hosting a
+delicate interplay between spin-orbit coupling and electronic correlations. We
+demonstrate that below the transition temperature at 105 K, $\text{SrIrO}_3$
+orthorhombic domains couple directly to tetragonal domains in $\text{SrTiO}_3$.
+This forces the in-phase rotational axis to lie in-plane and creates a binary
+domain structure in the $\text{SrIrO}_3$ film. The close proximity to the
+metal-insulator transition in ultrathin $\text{SrIrO}_3$ causes the individual
+domains to have strongly anisotropic transport properties, driven by a
+reduction of bandwidth along the in-phase axis. The strong structure-property
+relationships in perovskites make these compounds particularly suitable for
+static and dynamic coupling at interfaces, providing a promising route towards
+realizing novel functionalities in oxide heterostructures.",2002.10555v1
+2020-03-03,High-Speed Femto-Joule per Bit Silicon-Conductive Oxide Nanocavity Modulator,"By combining the large Purcell effect of photonic crystal nanocavity and the
+strong plasma dispersion effect of the transparent conductive oxides,
+ultra-compact silicon modulators with heterogeneously integrated
+indium-tin-oxide (ITO) can potentially achieve unprecedented energy efficiency
+to atto-joule per bit. In this article, we report the first high-speed silicon
+nanocavity modulator driven by an ITO gate, achieving 2.2 GHz bandwidth.
+On-off-key modulation is measured up to 5 Gb/s with only 2 V voltage swing and
+18.3 fJ/bit energy efficiency. In addition, we perform in-depth analysis of the
+energy efficiency and high frequency simulation of the nanocavity modulator,
+revealing the critical role played by the semiconductor conduction path and the
+overlapping factor between the accumulated free carriers and the cavity
+resonant mode. Based on our analysis, we propose a strategy to further improve
+the modulation bandwidth to 23.5 GHz by node-matched doping and reduce the
+energy consumption to the range of hundreds of atto-joule per bit.",2004.00983v1
+2020-04-02,In-situ Synthesis of Bismuth/Reduced Graphene Oxide Nanocomposites as High Capacity Anode Materials for Mg-ion Battery,"Herein, in-situ reduction of bismuth and graphene oxide was performed by a
+solvothermal method under a nitrogen atmosphere, and the resulting Bi on RGO
+nanocomposites were used as an anode material for Mg-ion batteries. The
+nanocomposite of 60% Bi:40% RGO is a beneficial anode material, delivering a
+discharge capacity as high as 413 and 372 mAh per g at the specific current of
+39 mA per g in the 1st and 50th cycles, respectively. In addition, it shows
+high-rate capability with the discharge capacities of 381, 372, 354, 295, and
+238 mAh per g at the specific currents of 53, 100, 200, 500, and 700 mA per g,
+respectively. The better electrochemical performance of the nanocomposite is
+due to improvement in the electronic conductivity and significant reduction of
+volume changes during electrochemical cycling. This study demonstrates the
+bismuth (Bi) on reduced graphene oxide (RGO) nanocomposite as a promising
+high-capacity anode for magnesium-ion batteries with longer life cycle and
+high-rate performance.",2004.06485v1
+2020-04-29,"Raman spectroscopy of ion irradiated SiC: chemical defects, strain, annealing, and oxidation","Raman spectroscopy has been used to identify defective bonding in neon and
+silicon ion irradiated single crystals of 6H-SiC. Observable differences exist
+in the C-C bonding region corresponding to different defect structures for neon
+and silicon ion implantations. Raman spectra of ion irradiated SiC show less
+tensile strain than neutron irradiations, explained by a residual compressive
+stress caused by the swelling constrained by the undamaged substrate. Evidence
+of oxidation during high temperature ion implantation is observed as C-O and
+Si-O Raman signals. Annealing irradiated SiC while acquiring Raman spectra
+shows rapid recovery of Si-C bonding, but not a complete recovery of the
+unirradiated structure. Annealing irradiated SiC causes surface oxidation where
+unirradiated SiC does not oxidise. Comparisons are made to the apparent
+radiation resistance of diamond and silicon which have similar crystal
+structures, but are monatomic, leading to the suggestion that chemical defects
+are responsible for increased radiation damage in SiC.",2004.14335v3
+2020-12-02,Bio-Based Polyether from Limonene Oxide Catalytic ROP as Green Polymeric Plasticizer for PLA,"In this work, the polymerization of Limonene Oxide (LO) has been achieved
+using an Earth abundant metal-based catalyst developed in our group, that is
+very active in ring opening polymerization (ROP) processes. The bio-based
+polylimonene ether (PLO) obtained had low molecular weight and good thermal
+properties, thus being a potential green polymeric additive for other bio-based
+polymers such as PLA. Hence, we have explored its ability to influence PLA
+properties. The addition of only 10 wt %, led to the modification and
+improvement of PLA properties in terms of flexibility, thermal stability, and
+hydrophobicity. The results obtained are promising and open up the potential
+industrial application of polylimonene oxide (PLO) for the melt-processing of
+blends based on PLA/PLO. These new materials are totally based on renewable
+sources and may be interesting for many applications where biodegradability and
+reduced water adsorption is required, such as food packaging or agricultural
+mulch films.",2012.01297v1
+2020-12-25,Graphene oxide based synaptic memristor device for neuromorphic computing,"Brain-inspired neuromorphic computing which consist neurons and synapses,
+with an ability to perform complex information processing has unfolded a new
+paradigm of computing to overcome the von Neumann bottleneck. Electronic
+synaptic memristor devices which can compete with the biological synapses are
+indeed significant for neuromorphic computing. In this work, we demonstrate our
+efforts to develop and realize the graphene oxide (GO) based memristor device
+as a synaptic device, which mimic as a biological synapse. Indeed, this device
+exhibits the essential synaptic learning behavior including analog memory
+characteristics, potentiation and depression. Furthermore,
+spike-timing-dependent-plasticity learning rule is mimicked by engineering the
+pre- and post-synaptic spikes. In addition, non-volatile properties such as
+endurance, retentivity, multilevel switching of the device are explored. These
+results suggest that Ag/GO/FTO memristor device would indeed be a potential
+candidate for future neuromorphic computing applications.
+  Keywords: RRAM, Graphene oxide, neuromorphic computing, synaptic device,
+potentiation, depression",2012.13556v1
+2021-01-29,"Comment on ""A compilation and bioenergetic evaluation of syntrophic microbial growth yields in anaerobic digestion"" by Patón, M. and Rodríguez, J. [Water Research 162 (2019), 516-517]","Recent efforts have focused on providing a systematic analysis of syntrophic
+microbial growth yields. These biokinetic parameters are key to developing an
+accurate mathematical description of the anaerobic digestion process. The
+agreement between experimentally determined growth yields and those obtained
+from bioenergetic estimations is therefore of great interest. Considering five
+important syntrophic groups, including acetoclastic and hydrogenotrophic
+methanogens, as well as propionate, butyrate and lactate oxidizers, previous
+findings suggest that measured and estimated growth yields were consistent only
+for acetoclastic methanogens. A re-analysis revealed that data are also
+consistent for lactate oxidizers and hydrogenotrophic methanogens, whereas the
+limited data available for propionate and butyrate oxidizers are unsupportive
+of firm conclusions. These results highlight pertinent challenges in the
+analysis of microbial syntrophy and encourage more accurate measurements of
+syntrophic microbial growth yields in the future.",2101.12342v1
+2012-05-17,Microscopic understanding of the orbital splitting and its tuning at oxide interfaces,"By means of a Wannier projection within the framework of density functional
+theory, we are able to identify the modified c-axis hopping and the energy
+mismatch between the cation bands as the main source of the $t_{2g}$ splitting
+around the $\Gamma$ point for oxide heterostructures, excluding previously
+proposed mechanisms such as Jahn-Teller distortions or electric field
+asymmetries. Interfacing LaAlO$_3$, LaVO$_3$, SrVO$_3$ and SrNbO$_3$ with
+SrTiO$_3$ we show how to tune this orbital splitting, designing
+heterostructures with more $d_{xy}$ electrons at the interface. Such an
+""orbital engineering"" is the key for controlling the physical properties at the
+interface of oxide heterostructures.",1205.4001v1
+2017-05-12,Highly oriented SrTiO3 thin film on graphene substrate,"Growth of perovskite oxide thin films on Si in crystalline form has long been
+a critical obstacle for the integration of multifunctional oxides into Si-based
+technologies. In this study, we propose pulsed laser deposition of a
+crystalline SrTiO3 thin film on a Si using graphene substrate. The SrTiO3 thin
+film on graphene has a highly (00l)-oriented crystalline structure which
+results from the partial epitaxy. Moreover, graphene promotes a sharp interface
+by highly suppressing the chemical intermixing. The important role of graphene
+as a 2D substrate and diffusion barrier allows expansion of device applications
+based on functional complex oxides.",1705.04412v1
+2017-05-16,The Structural Fate of Individual Multicomponent Metal-Oxide Nanoparticles in Polymer Nanoreactors,"Multicomponent nanoparticles can be synthesized with either homogeneous or
+phase-segregated architectures depending on the synthesis conditions and
+elements incorporated. To understand the parameters that determine their
+structural fate, multicomponent metal-oxide nanoparticles consisting of
+combinations of Co, Ni, and Cu were synthesized via scanning probe block
+copolymer lithography and characterized using correlated electron microscopy.
+These studies revealed that the miscibility, ratio of the metallic components,
+and the synthesis temperature determine the crystal structure and architecture
+of the nanoparticles. A Co-Ni-O system forms a rock salt structure largely due
+to the miscibility of CoO and NiO, while Cu-Ni-O, which has large miscibility
+gaps, forms either homogeneous oxides, heterojunctions, or alloys depending on
+the annealing temperature and composition. Moreover, a higher ordered
+structure, Co-Ni-Cu-O, was found to follow the behavior of lower ordered
+systems.",1705.05760v2
+2017-05-06,Three-fold Constructive Perturbation for Significant Enhancement in Field Emission from Nickel Oxide Nano-Thorn,"A power efficient and stable field emission (FE) has been reported here from
+Nickel Oxide nanostructures. Modification in device geometry and surface micro-
+(nano-) structure has been found helpful in addressing the bottlenecks in
+achieving an efficient FE . In terms of threshold and turn on fields, three
+orders of magnitude better electron FE has been observed in the nickel oxide
+nanopetals (NiO-NPs) fabricated using simple hydrothermal technique. Uniform
+and vertically aligned NiO-NPs structures, grown on very flat conducting
+surface (FTO coated glass), show sharp needles like structures on the top edges
+of the flakes. These ultrafine structures play the main role in field emission
+to start at such a low turn on fields. The FE data (J-E plot) has been fitted
+with Fowler-Nordheim (FN) equation to estimate threshold field value and field
+enhancement factor which are found to be 3 V/mm and $\sim$ 5 $\times$ 10$^6$
+respectively.",1705.07715v1
+2017-09-07,Synthesis of mixed hypermetallic oxide BaOCa$^+$ from laser-cooled reagents in an atom-ion hybrid trap,"Hypermetallic alkaline earth (M) oxides of formula MOM have been studied
+under plasma conditions that preclude insight into their formation mechanism.
+We present here the application of emerging techniques in ultracold physics to
+the synthesis of a mixed hypermetallic oxide, BaOCa$^+$. These methods,
+augmented by high-level electronic structure calculations, permit detailed
+investigation of the bonding and structure, as well as the mechanism of its
+formation via the barrierless reaction of Ca $(^3P_J)$ with BaOCH$_{3}^+$.
+Further investigations of the reaction kinetics as a function of collision
+energy over the range 0.005 K to 30 K and of individual Ca fine-structure
+levels compare favorably with calculations based on long-range capture theory.",1709.02399v1
+2017-09-22,Palladium gates for reproducible quantum dots in silicon,"We replace the established aluminium gates for the formation of quantum dots
+in silicon with gates made from palladium. We study the morphology of both
+aluminium and palladium gates with transmission electron microscopy. The native
+aluminium oxide is found to be formed all around the aluminium gates, which
+could lead to the formation of unintentional dots. Therefore, we report on a
+novel fabrication route that replaces aluminium and its native oxide by
+palladium with atomic-layer-deposition-grown aluminium oxide. Using this
+approach, we show the formation of low-disorder gate-defined quantum dots,
+which are reproducibly fabricated. Furthermore, palladium enables us to further
+shrink the gate design, allowing us to perform electron transport measurements
+in the few-electron regime in devices comprising only two gate layers, a major
+technological advancement. It remains to be seen, whether the introduction of
+palladium gates can improve the excellent results on electron and nuclear spin
+qubits defined with an aluminium gate stack.",1709.07699v2
+2018-03-12,Simultaneous nanopatterning and reduction of graphene oxide by femtosecond laser pulses,"This paper presents a novel one-step method for the periodical nanopatterning
+and reduction of graphene oxide (GO). Self-organized periodic structures of
+reduced graphene oxide (rGO) appear on GO surfaces upon processing with a
+femtosecond laser at fluences slightly higher than the fluence needed for
+reduction of the GO. This indicates that the periodic pattern is formed either
+simultaneously with or due to the reduction of the GO. The laser-induced
+reduction of GO was identified by sheet resistance measurements, Raman and
+X-ray photoelectron spectroscopy. This fast and simple method to both reduce
+and periodically structure GO offers a variety of possible applications in
+printed and flexible electronics.",1803.04350v1
+2018-03-14,Bond-Derived Orbitalwise Coordination Number as an Accurate Reactivity Descriptor for Oxygen Electrochemistry in Transition-Metal Oxides,"Unraveling a descriptor that is correlated with catalytic reactivity is
+essential for fast screening for the optimal catalysts for a given catalytic
+reaction. Herein, we propose bond-derived orbitalwise coordination number
+($\overline{CN}^\alpha$, $\alpha$= $s$ or $d$) as a simple and accurate
+descriptor used for transition metal (TM) oxides that takes into account both
+geometrical and electronic structures around active sites, and avoids excessive
+computation burden. This descriptor has a strong scaling relation with the
+activity in oxygen electrochemistry, enabling us to readily screen for the
+optimal catalyst for $\beta$-MnO$_2$. $\beta$-MnO$_2$ with
+$\overline{CN}^\alpha$=5.6 by creating an oxygen vacancy on (110) surface
+exhibits the best oxygen electrochemical activity, which is well consistent
+with experimetal result. This descriptor can be universally applied to other TM
+oxides, e.g. RuO$_2$, opening up a new route as a guideline to design novel
+catalysts in catalytic reactions.",1803.05146v2
+2018-03-20,Facile synthetic route to transition metal oxyfluorides via reactions between metal oxides and PTFE,"Inorganic oxyfluorides have significant importance in the development of new
+functionalities for energy production and storage, photonics, catalysis, etc.
+In order to explore a simple preparation route that avoids the use of toxic HF
+or F2 gas as a reaction reagent, we have employed polytetrafluoroethylene
+(PTFE). Five oxyfluorides including Nb5O12F, Nb3O7F, Ta3O7F, TaO2F, and
+Mo4O11.2F0.8 were synthesized by reactions between PTFE and transition metal
+oxides in sealed quartz ampules. The reaction mechanism was studied by means of
+gas analysis, which detected SiF4 as a main product gas during the reaction. A
+possible reaction mechanism between the PTFE and transition metal oxides is
+discussed.",1803.07229v1
+2018-03-21,Formation of periodical metal oxide multilayer structures for the X-ray standing wave applications,"Periodical multilayer (ML) structures can be used as generators of X-ray
+standing waves (XSW) for investigation of objects and processes on solid/liquid
+and solid/gas interfaces. In this paper, we investigate the specific
+requirements to the structural properties of the multilayer structures for XSW
+application. We consider the effect of typical defects in the ML structure on
+the X-ray standing wave formation and show that the X-ray standing wave is very
+robust against the random imperfection in the multilayer structure. In
+contrast, the roughness of the topmost layer will have a strong influence on
+the XSW experimental results, as the ML serves as a support for the
+investigated objects, so that the surface geometry gets directly translated
+into the objects. In the experimental part of this work, we have used the
+ion-beam deposition to grow Ni/Al metal- and metal oxide-based multilayers and
+investigate with AFM their surface quality. The presented results demonstrate
+that metal oxides can be successfully used as basic material for X-ray
+multilayer standing wave generators.",1803.07971v1
+2018-06-09,Origin of interfacial conductivity at complex oxide heterointerfaces: possibility of electron transfer from water chemistry at surface oxygen vacancies,"Variety of conducting heterointerfaces have been made between SrTiO3
+substrates and thin capping layers of distinctly different oxide materials that
+can be classified into polar band insulators (e.g. LaAlO3), polar Mott
+insulators (e.g. LaTiO3), apparently non-polar band insulators (e.g.
+{\gamma}-Al2O3), and amorphous oxides (e.g. amorphous SrTiO3). A fundamental
+question to ask is if there is a common mechanism that governs interfacial
+conductivity in all these heterointerfaces. Here, we examined the conductivity
+of different kinds of heterointerfaces by annealing in oxygen and surface
+treatment with water. It was found that the conductivity of all the
+heterointerfaces show a strong dependence on annealing, and can be universally
+tuned by surface treatment whose effect is determined by the annealing
+condition. These observations, together with ambient-pressure X-ray
+photoelectron spectroscopy measurements, suggest that water chemistry at
+surface oxygen vacancies is a common mechanism that supplies electrons to the
+interface.",1806.03407v1
+2018-06-14,Strain-induced tuning of the electronic Coulomb interaction in 3d transition metal oxide perovskites,"Epitaxial strain offers an effective route to tune the physical parameters in
+transition metal oxides. So far, most studies have focused on the effects of
+strain on the bandwidths and crystal field splitting, but recent experimental
+and theoretical works have shown that also the effective Coulomb interaction
+changes upon structural modifications. This effect is expected to be of
+paramount importance in current material engineering studies based on
+epitaxy-based material synthesization. Here, we perform constrained random
+phase approximation calculations for prototypical oxides with a different
+occupation of the d shell, LaTiO3 (d1), LaVO3 (d2), and LaCrO3 (d3), and
+systematically study the evolution of the effective Coulomb interactions
+(Hubbard U and Hund's J) when applying epitaxial strain. Surprisingly, we find
+that the response upon strain is strongly dependent on the material. For
+LaTiO3, the interaction parameters are determined by the degree of localization
+of the orbitals, and grow with increasing tensile strain. In contrast, LaCrO3
+shows the opposite trends: the interactions parameters shrink upon tensile
+strain. This is caused by the enhanced screening due to the larger electron
+filling. LaVO3 shows an intermediate behavior.",1806.05503v1
+2018-06-26,Spatiotemporal pattern formation in a three-variable CO oxidation reaction model,"The spatiotemporal pattern formation is studied in the catalytic carbon
+monoxide oxidation reaction that takes into account the diffusion processes
+over the Pt(110) surface, which may contain structurally different areas. These
+areas are formed during CO-induced transition from a reconstructed phase with
+$1\times2$ geometry of the overlayer to a bulk-like ($1\times1$) phase with
+square atomic arrangement. Despite the CO oxidation reaction being
+non-autocatalytic, we have shown that the analytic conditions of the existence
+of the Turing and the Hopf bifurcations can be satisfied in such systems. Thus,
+the system may lose its stability in two ways --- either through the Hopf
+bifurcation leading to the formation of temporal patterns in the system or
+through the Turing bifurcation leading to the formation of regular spatial
+patterns. At a simultaneous implementation of both scenarios, spatiotemporal
+patterns for CO and oxygen coverages are obtained in the system.",1806.09960v1
+2018-07-27,Current developments of nanoscale insight into corrosion protection by passive oxide films,"Oxide passive films are a key for the durability of metals and alloys
+components as well as a central issue in corrosion science and engineering.
+Herein, we discuss current developments of the nanometer and sub-nanometer
+scale knowledge of the barrier properties and adsorption properties of passive
+oxide films brought by recent model experimental and theoretical
+investigations. The discussed aspects include (i) the chromium enrichment and
+its homogeneity at the nanoscale in passive films formed on Cr-bearing alloys
+such as stainless steel, (ii) the corrosion properties of grain boundaries in
+early intergranular corrosion before penetration and propagation in the grain
+boundary network, and (iii) the interaction of organic inhibitor molecules with
+incompletely passivated metallic surfaces. In all three cases, key issues are
+highlighted and future developments that we consider as most relevant are
+identified.",1807.10689v2
+2018-08-04,Implementation and Analysis of Stable PUFs Using Gate Oxide Breakdown,"We implement and analyze highly stable PUFs using two random gate oxide
+breakdown mechanisms: plasma induced breakdown and voltage stressed breakdown.
+These gate oxide breakdown PUFs can be easily implemented in commercial silicon
+processes, and they are highly stable. We fabricated bit generation units for
+the stable PUFs on 99 testchips with 65nm CMOS bulk technology. Measurement
+results show that the plasma induced breakdown can generate complete stable
+responses. For the voltage stressed breakdown, the responses are with 0.12\%
+error probability at a worst case corner, which can be effectively accommodated
+by taking the majority vote from multiple measurements. Both PUFs show
+significant area reduction compared to SRAM PUF. We compare methods for
+evaluating the security level of PUFs such as min-entropy, mutual information
+and guesswork as well as inter- and intra-FHD, and the popular NIST test suite.
+We show that guesswork can be viewed as a generalization of min-entropy and
+mutual information. In addition, we analyze our testchip data and show through
+various statistical distance measures that the bits are independent. Finally,
+we propose guesswork as a new statistical measure for the level of statistical
+independence that also has an operational meaning in terms of security.",1808.01516v1
+2018-06-18,Energy and exergy analysis of solar stills with micro/nano particles: A comprehensive study,"In this paper, a comparative study between modified solar stills (with
+graphite or copper oxide micro/nano particles) and classical solar still is
+carried out, based on the productivity and the thermal performance. Exergy
+destructions in various components of the solar stills have been calculated,
+analyzed and discussed. Evaporation is faster and the exergy of evaporation is
+higher at the modified solar stills than that of the classical one.
+Furthermore, the energy and exergy efficiencies of the modified stills are
+enhanced compared with the classical one. A brief discussion regarding the
+effect of different parameters on solar stills efficiency is also presented.
+The daytime energy efficiency of graphite/water and copper oxide/water mixtures
+are 41.18% and 38.61%, respectively, but for the classical still is only
+29.17%. Moreover, the daytime exergy efficiencies of graphite, copper oxide
+nanofluid based stills and classical still are 4.32%, 3.78% and 2.63%,
+respectively.",1808.01875v1
+2018-08-09,Amphoteric behavior of Hydrogen in Bimetallic Molecular like Hydrides,"Generally hydrogen will adopt the +1, 0 or -1 oxidation state in solids
+depending upon the chemical environment it occupy. Typically, there are some
+exceptional cases in which hydrogen exhibits both anionic and cationic behavior
+in the same structural frame works. In this study we briefly explore an
+amphoteric behavior of hydrogen present in ammine bimetallic borohydrides with
+the chemical formula M1M2 (BH4)3 (NH3)2 (M1= Na; M2 = Zn, Mg) using the
+state-of-the-art density functional calculations. In order to establish the
+amphoteric behavior of hydrogen in M1M2 (BH4)3 (NH3)2, we have made detailed
+chemical bonding analyses using partial density of states, charge density,
+electron localization function, and Born effective charge. From these analyses
+we found that the hydrogen closer to boron is in negative oxidation state
+whereas the hydrogen closer to nitrogen is in positive oxidation state. The
+establishment of the present of hydrogen with amphoteric behavior in solids has
+large implication on hydrogen storage application.",1808.03020v1
+2018-08-09,Switchable and tunable Rashba-type spin splitting in covalent perovskite oxides,"In transition metal perovskites (ABO3) most physical properties are tunable
+by structural parameters such as the rotation of the BO6 octahedra. Examples
+include the N\'eel temperature of orthoferrites, the conductivity of
+mixed-valence manganites, or the band gap of rare-earth scandates. Since oxides
+often host large internal electric dipoles and can accommodate heavy elements,
+they also emerge as prime candidates to display Rashba spin-orbit coupling,
+through which charge and spin currents may be efficiently interconverted.
+However, despite a few experimental reports in SrTiO3-based interface systems,
+the Rashba interaction has been little studied in these materials, and its
+interplay with structural distortions remain unknown. In this Letter, we
+identify a bismuth-based perovskite with a giant, electrically-switchable
+Rashba interaction whose amplitude can be controlled by both the ferroelectric
+polarization and the breathing mode of oxygen octahedra. This particular
+structural parameter arises from the strongly covalent nature of the Bi-O
+bonds, reminiscent of the situation in perovskite nickelates. Our results not
+only provide novel strategies to craft agile spin-charge converters but also
+highlight the relevance of covalence as a powerful handle to design emerging
+properties in complex oxides.",1808.03123v1
+2018-08-13,Reduced graphene oxide for control of octahedral distortion in orthorhombic Pbnm perovskite,"Perovskites and related structures are renowned for technologically useful
+applications. The structural variations in perovskite crystals result in novel
+properties which can be regulated by external forces. The study attempts to
+regulate distortion of a perovskite compound LaFeO3 driven solely by reduced
+graphene oxide (RGO) and to demonstrate the effect using a critical parameter -
+electrochemical conductivity. A series of graphene concentration varied
+nanocomposites were synthesized via hydrothermal method. The crystal distortion
+is investigated using X-ray diffraction and Rietveld refinement. By analysis of
+the oxygen and Fe ion peaks of X-ray photoelectron spectroscopy, along with
+Raman spectra, a clear understanding of the distortion process is developed.
+The remarkable effect of distortion on dispersed phases generated by graphene
+matrix is coined with a new phrase Graphenostortion. The study revealed that
+the environment for the graphenostrotion originated from the interaction of
+oxygen functional groups of RGO with LaFeO3. The variation in bond covalency
+influenced by the percentage concentration of non-lattice oxygen, distorted the
+Pbnm geometry of the graphene nanocomposite. The developed mechanism for
+distortion is in good agreement with electrochemical activity studies. RGO as a
+tool to control distortion in metal oxide could facilitate new facets in
+technological applications of graphene nanocomposites.",1808.04105v1
+2018-08-16,Investigating Unipolar Switching in Niobium Oxide Resistive Switches: Correlating Quantized Conductance and Mechanism,"Memory devices based on resistive switching (RS) have not been fully realised
+due to lack of understanding of the underlying switching mechanisms. Nature of
+ion transport responsible for switching and growth of conducting filament in
+transition metal oxide based RS devices is still in debate. Here, we
+investigated the mechanism in Niobium oxide based RS devices, which shows
+unipolar switching with high ON/OFF ratio, good endurance cycles and high
+retention times. We controlled the boundary conditions between low-conductance
+insulating and a high-conductance metallic state where conducting filament (CF)
+can form atomic point contact and exhibit quantized conductance behaviour.
+Based on the statistics generated from quantized steps data, we demonstrated
+that the CF is growing atom by atom with the applied voltage sweeps. We also
+observed stable quantized states, which can be utilized in multistate
+switching.",1808.05600v1
+2018-12-07,Gate-tunable near-field heat transfer,"Active control over the flow of heat in the near-field holds promise for
+nanoscale thermal management, with applications in refrigeration,
+thermophotovoltaics, and thermal circuitry. Analogously to its electronic
+counterpart, the metal-oxide-semiconductor (MOS) capacitor, we propose a
+thermal switching mechanism based on accumulation and depletion of charge
+carriers in an ultra-thin plasmonic film, via application of external bias. In
+our proposed configuration, the plasmonic film is placed on top of a
+polaritonic dielectric material that provides a surface phonon polariton (SPhP)
+thermal channel, while also ensuring electrical insulation for application of
+large electric fields. The variation of carrier density in the plasmonic film
+enables the control of the surface plasmon polariton (SPP) thermal channel. We
+show that the interaction of the SPP with the SPhP significantly enhances the
+net heat transfer. We study SiC as the oxide and explore three classes of
+gate-tunable plasmonic materials: transparent conductive oxides, doped
+semiconductors, and graphene, and theoretically predict contrast ratios as high
+as 225%.",1812.02882v1
+2018-09-30,Main-chain poly(ionic liquid)-derived nitrogen-doped micro/mesoporous carbons for CO2 capture and selective aerobic oxidation of alcohols,"Sustainable development and the recent fast growing global demands for energy
+and functional chemicals urgently call for effective methods for CO2
+remediation and efficient metal-free catalysts for selective oxidation of
+aromatic alcohol. Herein, a unique main-chain poly(ionic liquid) (PIL) is
+employed as the precursor to prepare nitrogen doped micro and mesoporous
+carbons via simultaneous carbonization and activation, which bear high yield,
+large specific surface area above 1700 m2 per g and rich nitrogen dopant. The
+porous carbon products deliver a high CO2 adsorption capacity up to 6.2 mmol
+per g at 273 K and 1 bar with outstanding reversibility and satisfactory
+selectivity. Besides, they work excellently as metal free carbocatalysts for
+the selective aerobic oxidation of benzyl alcohol to benzaldehyde with high
+selectivity. It is believed that this work not only provides a facile approach
+to prepare nitrogen-doped porous carbon, but also advances the related research
+in the fields of environment and catalysis.",1812.11014v1
+2018-12-29,Understanding the origin of bandgap problem in transition and post-transition metal oxides,"Improving electronic structure calculations for practical and
+technologically-important materials has been a never-ending pursue. This is
+especially true for transition and post-transition metal oxides for which the
+current first-principles approaches still suffer various drawbacks. Here we
+present a hierarchical-hybrid functional approach built on the use of
+pseudopotentials. The key is to introduce a discontinuity in the exchange
+functional between core and valence electrons. It allows for treating the
+localization errors of sp and d electrons differently, which have been known to
+be an important source of error for the band gap. Using ZnO as a prototype, we
+show the approach is successful in simultaneously reproducing the band gap and
+d-band position. Remarkably, the same approach, without having to change the
+hybrid mixing parameters from those of Zn, works reasonably well for other
+binary 3d transition and post-transition metal oxides across board. Our
+findings point to a new direction of systematically improving the exchange
+functional in first-principles calculations.",1812.11288v2
+2019-01-09,Exploitation of Transparent Conductive Oxides in the Implementation of a Window-Integrated Wireless Sensor Node,"Exploitation of transparent conductive oxides (TCO) to implement an
+energy-autonomous sensor node for a wireless sensor network (WSN) is studied
+and a practical solution presented. In the practical implementations, flexible
+and rigid substrates that is polyimide and glass, are coated with TCO, namely
+aluminum doped zinc oxide (AZO). AZO-coated flexible substrates are used to
+form thermoelectric generators (TEG) that produce electricity for the sensor
+electronics of the node from thermal gradients on a window. As the second
+solution to utilize AZO, its conductive properties are exploited to implement
+transparent antennas for the sensor node. Antennas for a UHF RFID transponder
+and the Bluetooth radio of the node are implemented. A prototype of a flexible
+transparent TEG, with the area of 67 cm2 when folded, was measured to produce
+power of 1.6 uW with a temperature difference of 43 K. A radiation efficiency
+of -9.1 dB was measured for the transparent RFID antenna prototype with the
+center frequency of 900 MHz. Radiation efficiencies between -3.8 dB and -0.4
+dB, depending on the substrate, were obtained for the 2.45 GHz Bluetooth
+antenna.",1901.02699v1
+2019-01-17,Reduction of interface state density in SiC (0001) MOS structures by low-oxygen-partial-pressure annealing,"We report that annealing in low-oxygen-partial-pressure (low-p$_{\rm O2}$)
+ambient is effective in reducing the interface state density (D$_{\rm IT}$) at
+a SiC (0001)/SiO$_{\rm 2}$ interface near the conduction band edge (E$_{\rm
+C}$) of SiC. The D$_{\rm IT}$ value at E$_{\rm C}$$-$0.2 eV estimated by a high
+(1 MHz)-low method is 6.2$\times$10$^{12}$ eV$^{-1}$cm$^{-2}$ in as-oxidized
+sample, which is reduced to 2.4${\times}$10$^{12}$ eV$^{-1}$cm$^{-2}$ by
+subsequent annealing in O$_{\rm 2}$ (0.001%) at 1500${}^\circ$C, without
+interface nitridation. Although annealing in pure Ar induces leakage current in
+the oxide, low-p$_{\rm O2}$ annealing (p$_{\rm O2}$ = 0.001 - 0.1 %) does not
+degrade the oxide dielectric property (breakdown field ~ 10.4 MVcm$^{-1}$).",1901.05681v1
+2019-01-17,Surface coating with oxide layers to enhance the spin properties of shallow NV centers in diamond,"We present an enhancement of spin properties of the shallow (<5nm) NV centers
+by using ALD to deposit titanium oxide layer on the diamond surface. With the
+oxide layer of an appropriate thickness, increases about 2 up to 3.5 times of
+both relaxation time and evolution time were achieved and the shallow NV center
+charge states stabilized as well. Moreover, the coherence time kept almost
+unchanged. This surface coating technique could produce a protective coating
+layer of controllable thickness without any damages to the solid quantum system
+surface, making it possible to prolong T1 time and T2* time, which would be a
+possible approach to the further packaging technique for the applicating solid
+quantum devices.",1901.05728v4
+2019-01-23,Hydrogen sensing characteristics of perovskite based calcium doped BiFeO3 thin films,"Perovskite oxide based thin film gas sensors have long been considered as
+potential alternatives to commonly investigated binary metal oxides based
+sensors. BiFeO3, which is a prototype of p-type perovskite based semiconducting
+oxides, has recently drawn significant attention for its promising gas sensing
+characteristics. In the present work, the hydrogen sensing characteristics of
+calcium doped BiFeO3 has been reported by varying the film thickness, doping
+concentration, operating temperature, and test gas concentration. The films
+were deposited on glass substrates by sol-gel route using spin coating. X-ray
+diffraction analyses confirmed formation of phase pure films and scanning
+electron microscopy confirmed their uniform and dense microstructure. The
+Ca-doped BiFeO3 sensors exhibit higher sensitivity compared to pure BiFeO3
+sensors. It is reported that the film thickness and Ca doping concentration
+play major role to control hydrogen sensing characteristics of the deposited
+films. The sensor based on 15% Ca-doped BiFeO3 sensor exhibited very high
+sensitivity (~212 % at 500 ppm H2), and excellent selectivity towards hydrogen
+at a moderate operating temperature (~250 {\deg}C).The enhanced gas sensing
+response of the doped BiFeO3 films has been attributed to the higher oxygen
+vacancy concentration induced by incorporation of aliovalent Ca2+.",1901.07745v1
+2019-02-09,"Comparative first-principles study of antiperovskite oxides and nitrides as thermoelectric material: multiple Dirac cones, low-dimensional band dispersion, and high valley degeneracy","We perform a comparative study on thermoelectric performance of
+antiperovskite oxides $Ae_3Tt$O and nitrides $Ae_3Pn$N ($Ae=$ Ca, Sr, Ba; $Tt=$
+Ge, Sn, Pb; $Pn=$ As, Sb, Bi) by means of first-principles calculation. As for
+the oxides with the cubic structure, Ca$_3$GeO with a sizable band gap exhibits
+high thermoelectric performance at high temperatures, while Ba$_3$PbO with
+Dirac cones without the gap is favorable at low temperatures. The latter high
+performance owes to high valley degeneracy including the multiple Dirac cones
+and the valleys near the $\Gamma$ and R points. For the nitrides with the cubic
+structure, insulator with strong quasi-one-dimensionality exhibits high
+thermoelectric performance. We also find that the orthorhombic structural
+distortion sometimes sizably enhances thermoelectric performance, especially
+for Ba$_3$GeO and Sr$_3$AsN where the high valley degeneracy is realized in the
+$Pnma$ phase. Our calculation reveals that antioerpvskites offer a fertile
+playground of various kinds of characteristic electronic structure, which
+enhance the thermoelectric performance, and provides promising candidates of
+high-performance thermoelectric materials.",1902.03424v2
+2019-02-19,"Mono- versus multi-phosphonic acid based PEGylated polymers for functionalization and stabilization of metal (Ce, Fe, Ti, Al)oxide nanoparticles in biological media","For applications in nanomedicine, particles need to be functionalized to
+prevent protein corona formation and or aggregation. Most advanced strategies
+take advantage of functional polymers and assembly techniques. Nowadays there
+is an urgent need for coatings that are tailored according to a broad range of
+surfaces and that can be produced on a large scale. Herein, we synthesize mono-
+and multi-phosphonic acid based poly(ethylene glycol) (PEG) polymers with the
+objective of producing efficient coats for metal oxide nanoparticles. Cerium,
+iron, titanium and aluminum oxide nanoparticles of different morphologies
+(spheres, platelets, nanoclusters) and sizes ranging from 7 to 40 nm are
+studied in physiological and in protein rich cell culture media. It is found
+that the particles coated with mono-functionalized polymers exhibit a mitigated
+stability over time, whereas the multi-functionalized copolymers provide
+resilient coatings and long-term stability (months). With the latter, PEG
+densities in the range 0.2 - 0.5 nm-2 and layer thickness about 10 nm provide
+excellent performances. The study suggests that the proposed coating allows
+controlling nanomaterial interfacial properties in biological environments.",1902.07172v1
+2019-03-07,Electrochemical performance of decorated reduced graphene oxide by MoO3 nanoparticles as a counter electrode,"We present an efficient electrocatalytic material based on anchored MoO3
+nanoparticles on reduced graphene oxide (RGO) nanosheets. After preparation of
+graphene oxide (GO), the MoO3 nanoparticles anchored on GO nanosheet by using
+the arc-discharge method. X-ray diffraction patterns show that the MoO3
+nanoparticles are well crystallized on RGO in the orthorhombic crystalline
+phase with a crystallite size of 83 nm. In addition, FT-IR and Raman
+spectroscopy results show that during the arc-discharge process, the GO
+nanosheets have been reduced and RGO nanosheets are decorated with MoO3
+nanoparticles which form a porous structure. The surface energy of the prepared
+electrode was measured as 44.56 mJ/m2, which shows the desirable spreading
+ability of the electrolyte on the electrode. Finally, electrochemical
+performance was measured in the symmetrical dummy cell by impedance
+spectroscopy and cyclic voltammogram, and the photochemical test was measured
+in the dye-sensitized solar cell by current density measurement. Our results
+show that the electrochemical performance of the RGM electrode is better than
+the RGO electrode and is comparable with the Platinum electrode and also the
+efficiency of RGM electrode used in a dye-sensitized solar cell as a counter
+electrode is 5.55% near to Platinum electrode performance.",1903.02914v2
+2019-03-08,Quantised conductance of one-dimensional strongly-correlated electrons in an oxide heterostructure,"Oxide heterostructures are versatile platforms with which to research and
+create novel functional nanostructures. We successfully develop one-dimensional
+(1D) quantum-wire devices using quantum point contacts on MgZnO/ZnO
+heterostructures and observe ballistic electron transport with conductance
+quantised in units of 2e^{2}/h. Using DC-bias and in-plane field measurements,
+we find that the g-factor is enhanced to around 6.8, more than three times the
+value in bulk ZnO. We show that the effective mass m^{*} increases as the
+electron density decreases, resulting from the strong electron-electron
+interactions. In this strongly interacting 1D system we study features matching
+the 0.7 conductance anomalies up to the fifth subband. This paper demonstrates
+that high-mobility oxide heterostructures such as this can provide good
+alternatives to conventional III-V semiconductors in spintronics and quantum
+computing as they do not have their unavoidable dephasing from nuclear spins.
+This paves a way for the development of qubits benefiting from the low defects
+of an undoped heterostructure together with the long spin lifetimes achievable
+in silicon.",1903.03476v1
+2019-03-10,Monolayer black phosphorus by sequential wet-chemical surface oxidation,"We report a straightforward chemical methodology for controlling the
+thickness of black phosphorus flakes down to the monolayer limit by
+layer-by-layer oxidation and thinning, using water as solubilizing agent.
+Moreover, the oxidation process can be stopped at will by two different
+passivation procedures, namely the non-covalent functionalization with perylene
+diimide chromophores, which prevents the photooxidation, or by using a
+protective ionic liquid layer. The obtained flakes preserve their electronic
+properties as demonstrated by fabricating a BP field-effect transistor (FET).
+This work paves the way for the preparation of BP devices with controlled
+thickness",1903.03972v1
+2019-03-12,Plasmon Standing Waves by Oxidation of Si(553)-Au,"Self-assembled Au atomic wires on stepped Si surfaces are metallic, as
+evidenced by a one-dimensionally dispersing plasmonic excitation. Here we
+investigate the effects of oxidization on metallicity along such Au atomic
+wires on a regularly stepped Si(553) surface, by employing infrared absorption
+and high resolution electron energy loss spectroscopies. Our results indicate
+that only the Si environment undergoes oxidation, which has a remarkably small
+effect on the plasmon dispersion. Only close to $k_{\parallel}\rightarrow 0$
+the plasmon dispersion ends at increasingly higher energies as a function of
+oxygen exposure, which is attributed to standing wave formation on small
+sections of Au wires generated by the introduction of O atoms as scattering
+centers, not to electronic gap opening. This interpretation is in full
+agreement with the findings by infrared spectroscopy and with low energy
+electron diffraction.",1903.04826v1
+2019-03-29,Epitaxial TiOx Surface in Ferroelectric BaTiO3: Native Structure and Dynamic Patterning at the Atomic Scale,"Surfaces and interfaces of ferroelectric oxides exhibit enhanced
+functionality, and therefore serve as a platform for novel nano and quantum
+technologies. Experimental and theoretical challenges associated with examining
+the subtle electro-chemo-mechanical balance at metal-oxide surfaces have
+hindered the understanding and control of their structure and behavior. Here,
+we combine advanced electron-microscopy and first-principles thermodynamics
+methods to reveal the atomic-scale chemical and crystallographic structure of
+the surface of the seminal ferroelectric BaTiO3. We show that the surface is
+composed of a native < 2-nm thick TiOx rock-salt layer in epitaxial registry
+with the BaTiO3. Using electron-beam irradiation, we successfully patterned
+artificially TiOx sites with sub-nanometer resolution, by inducing Ba escape.
+Therefore, our work offers electro-chemo-mechanical insights into ferroelectric
+surface behavior in addition to a method for scalable high-resolution
+beam-induced chemical lithography for selectively driving surface phase
+transitions, and thereby functionalizing metal-oxide surfaces.",1903.12435v1
+2019-03-29,Structural modification of thin Bi(1 1 1) films by passivation and native oxide model,"The structure of thin terminated Bi(1 1 1) films of approximately 1 nm
+thickness is investigated from first principles. Our density functional theory
+calculations show that covalent bonds to the surface can change the orientation
+of the films completely. For thicker films, the effect is limited to the
+surface only. Based on these observations, we further present a simple model
+structure for the native oxide and chemically similar oxides, which form a
+protective capping layer, leaving the orientation of the films unchanged. The
+advantages of this energetically favorable layered termination are discussed in
+the context of the films' technological exploitation in nanoelectronic devices.",1903.12654v2
+2019-04-06,Constriction Percolation Model for Coupled Diffusion-Reaction Corrosion of Zirconium in PWR,"Percolation phenomena are pervasive in nature, ranging from capillary flow,
+crack propagation, ionic transport, fluid permeation, etc. Modeling percolation
+in highly-branched media requires the use of numerical solutions, as problems
+can quickly become intractable due to the number of pathways available. This
+becomes even more challenging in dynamic scenarios where the generation of
+pathways can quickly become a combinatorial problem. In this work, we develop a
+new constriction percolation paradigm, using cellular automata to predict the
+transport of oxygen through a stochastically cracked Zr oxide layer within a
+coupled diffusion-reaction framework. We simulate such branching trees by
+generating a series porosity-controlled media. Additionally, we develop an
+analytical criterion based on compressive yielding for bridging the transition
+state in corrosion regime, where the percolation threshold has been achieved.
+Our model extends Dijkstras shortest path method to constriction pathways and
+predicts the arrival rate of oxygen ions at the oxide interface. This is a
+critical parameter to predict oxide growth in the so-called post-transition
+regime, when bulk diffusion is no longer the rate-limiting phenomenon.",1904.03344v1
+2019-04-10,Influence of vacuum annealing on interface properties of SiC (0001) MOS structures,"We investigated the influence of vacuum annealing on interface properties of
+silicon carbide (SiC) metal-oxide-semiconductor (MOS) structures. For
+as-oxidized and nitric oxide (NO)-annealed samples, the interface state density
+($D_{\rm it}$) near the conduction band edge ($E_{\rm C}$) of SiC did not
+increase by subsequent vacuum annealing. For phosphoryl chloride
+(POCl$_3$)-annealed samples, in contrast, $D_{\rm it}$ at $E_{\rm C}-0.2$ eV
+increased from $1.3\times10^{10}$ to $2.2\times10^{12}$ cm$^{-2}$eV$^{-1}$ by
+the vacuum annealing, and the channel mobility of MOS field effect transistors
+(MOSFETs) decreased from 109 to 44 cm$^2$V$^{-1}$s$^{-1}$. Mechanism of the
+observed increase in $D_{\rm it}$ was discussed based on the results of
+secondary ion mass spectrometry measurement.",1904.05006v1
+2019-04-12,Synthesis of anti-perovskite-type carbides and nitrides from metal oxides and melamine,"Four anti-perovskite-type compounds, ZnNNi3, ZnCNi3, SnNCo3, and SnCCo3, are
+synthesised through reactions between ingredient metal oxides and organic
+compound melamine (C3H6N6). ZnNNi3 and ZnCNi3 are selectively synthesised by
+choosing different reaction temperatures and nominal oxide-to-melamine ratios.
+SnNCo3 is synthesised for the first time by this melamine method. Resistivity,
+magnetisation, and heat capacity measurements reveal that SnNCo3 is a
+correlated metal with a high density of states at the Fermi level. Our results
+demonstrate that this feasible synthetic route using melamine is useful in the
+search for complex metal carbides and nitrides toward novel functional
+materials.",1904.06103v1
+2019-08-01,Liquid Marble Photosensor,"A liquid marble is a liquid droplet coated by a hydrophobic power. The liquid
+marble does not wet adjacent surfaces and therefore can be manipulated as a dry
+soft body. A Belousov-Zhabotinsky (BZ) reaction is an oscillatory chemical
+reaction exhibiting waves of oxidation. We demonstrate how to make a
+photo-sensor from BZ medium liquid marbles. We insert electrodes into a liquid
+marble, prepared from BZ solution and coated with polyethylene powder. The
+electrodes record a potential difference which oscillates due to oxidation
+wave-fronts crossing the electrodes. When the BZ marble is illuminated by a
+light source, the oxidation wave-fronts are hindered and, thus, the electrical
+potential recorded ceases to oscillate. We characterise several types of
+responses of BZ marble photosensors to various stimuli, and provide
+explanations of the recorded activity. BZ liquid marble photosensors may find
+applications in the fields of liquid electronics, soft robotics and
+unconventional computing.",1908.00632v1
+2019-08-02,Light scattering through the graphene oxide liquid crystal in a micro-channel,"In this paper, we examine the light scattering by the flow of levitated
+flakes in a micro-channel to characterize the tunable functionality of the
+graphene oxide liquid crystal in the nematic phase. Light interaction with the
+mentioned material is decomposed to the scattered and transmitted parts and
+they can determine the orientation of the flakes. Our results demonstrate that,
+pumping the graphene oxide sample through the micro-channel leads to increase
+the amplitude of scattered light. The time averaged of scattered light
+intensity grows by increasing volume fraction. We also find that, the higher
+volume fraction, the sooner reaching to saturated normalized scattered
+intensity is. To get deep insight about our experimental results, we rely on
+the general theoretical properties of the light scattering cross-section
+incorporating the fluctuation of director vector and dielectric tensor. Our
+proposal is a promising approach to carry out the mechanical-hydrodynamical
+approach for controlling the orientation of a typical liquid crystal.",1908.00725v1
+2019-08-05,Neutralization of slow helium ions scattered from single crystalline aluminum and tantalum surfaces and their oxides,"We investigated the impact of surface oxygen on the ion yield for He$^+$ ions
+scattered from different single crystalline surfaces in low-energy ion
+scattering. Initially clean Al(111) and Ta(111) were exposed to molecular
+oxygen and ion spectra for different oxidation stages and different primary
+energies were recorded. A comparison of ion yields normalized to the
+differential scattering cross section as well as experimental factors allows
+obtaining information about the influence of oxygen on charge exchange
+processes. The decrease in the ion yield of both metals with exposure cannot be
+explained by different surface coverages exclusively, but requires the
+neutralization efficiency to be dependent on the chemical structure of the
+surface. For Ta, additionally, a different energy dependency of the ion yield
+obtained in the metal and oxide occurs. The ion yield for O shows in both
+surfaces a significantly weaker energy dependency than the investigated metals.",1908.01629v1
+2019-08-08,Descriptors for Electrolyte-Renormalized Oxidative Stability of Solvents in Lithium-ion Batteries,"Electrolyte stability against oxidation is one of the important factors
+limiting the development of high energy density batteries. HOMO level of
+solvent molecules has been successfully used for understanding trends in their
+oxidative stability but assumes a non-interacting environment. However, solvent
+HOMO levels are renormalized due to molecules in their solvation shells. In
+this work, we first demonstrate an inexpensive and accurate method to determine
+the HOMO level of solvent followed by simple descriptors for renormalization of
+HOMO level due to different electrolyte components. The descriptors are based
+on Gutmann Donor and Acceptor numbers of solvent and other components. The
+method uses fast GGA-level DFT calculations compared to previously used
+expensive, experimental data dependent methods. This method can be used to
+screen for unexplored stable solvents among the large number of known organic
+compounds to design novel high voltage stable electrolytes.",1908.03285v1
+2019-08-21,Graphene Oxide Nanoparticles in the Interstellar Medium,"Dust particles play a major role in the formation, evolution and chemistry of
+interstellar clouds, stars and planetary systems. Commonly identified forms
+include amorphous and crystalline carbon-rich particles and silicates. Also
+present in many astrophysical environments are polycyclic aromatic hydrocarbons
+(PAHs), detected through their infrared emission, and which are essentially
+small flakes of graphene. Astronomical observations over the past four decades
+have revealed a widespread unassigned Extended Red Emission (ERE) feature which
+is attributed to luminescence of dust grains. Numerous potential carriers for
+ERE have been proposed but none has gained general acceptance. In this Letter
+it is shown that there is a strong similarity between laboratory optical
+emission spectra of graphene oxide and ERE, leading to this proposal that
+emission from graphene oxide nanoparticles is the origin of ERE and that these
+are a significant component of interstellar dust. The proposal is supported by
+infrared emission features detected by the Infrared Space Observatory (ISO) and
+the Spitzer Space Telescope.",1908.07787v1
+2019-11-01,Mesoscopic theory of defect ordering-disordering transitions in thin oxide films,"Ordering of mobile defects in functional materials can give rise to
+fundamentally new phases possessing ferroic and multiferroic functionalities.
+Here we develop the Landau theory for strain induced ordering of defects (e.g.
+oxygen vacancies) in thin oxide films, considering both the ordering and
+wavelength of possible instabilities. Using derived analytical expressions for
+the energies of various defect-ordered states, we calculated and analyzed phase
+diagrams dependence on the film-substrate mismatch strain, concentration of
+defects, and Vegard coefficients. Obtained results open possibilities to create
+and control superstructures of ordered defects in thin oxide films by selecting
+the appropriate substrate and defect concentration.",1911.00258v3
+2019-11-07,"Thermodynamic stability of Borophene, $\mathrm{B_2O_3}$ and other $\mathrm{B_{1-x}O_x}$ sheets","The recent discovery of borophene, a two-dimensional allotrope of boron,
+raises many questions about its structure and its chemical and physical
+properties. Boron has a high chemical affinity to oxygen but little is known
+about the oxidation behavior of borophene. Here we use first principles
+calculations to study the phase diagram of free-standing, two-dimensional
+$\mathrm{B_{1-x}O_x}$ for compositions ranging from $x=0$ to $x=0.6$, which
+correspond to borophene and $\mathrm{B_2O_3}$ sheets, respectively. Our results
+indicate that no stable compounds except borophene and $\mathrm{B_2O_3}$ sheets
+exist. Intermediate compositions are heterogeneous mixtures of borophene and
+$\mathrm{B_2O_3}$. Other hypothetical crystals such as $\mathrm{B_2O}$ are
+unstable and some of them were found to undergo spontaneous disproportionation
+into borophene and $\mathrm{B_2O_3}$. It is also shown that oxidizing borophene
+inside the flakes is thermodynamically unfavorable over forming
+$\mathrm{B_2O_3}$ at the edges. All findings can be rationalized by oxygen's
+preference of two-fold coordination which is incompatible with higher in-plane
+coordination numbers preferred by boron. These results agree well with recent
+experiments and pave the way to understand the process of oxidation of
+borophene and other two-dimensional materials.",1911.02950v1
+2019-11-17,Pt Supported on Plasma-Chemical Titanium Nitride for Efficient Room-Temperature CO Oxidation,"Catalysts of carbon monoxide oxidation were synthesized by deposition of
+platinum on titanium nitride (TiN). Two substrates with an average particle
+size of 18 and 36 nm were obtained by hydrogen reduction of titanium
+tetrachloride in a stream of microwave plasma of nitrogen. The surface of the
+catalysts was studied by X-ray photoelectron spectroscopy (XPS). The CO
+oxidation rate on the 9-15 wt.% Pt loaded TiN catalysts was found to be 120
+times higher than that on platinum black with a specific surface of 30 m2/g.
+Such catalysts are promising for use in catalytic air purification systems.",1911.07321v1
+2019-11-27,Comparative Study of RF Sputtered Ba2(BiNb)O6 and Ba2Bi1.4Nb0.6 O6 thin films and Effect of Fluorine Doping in Their Photoelectrochemical (PEC) Performances,"Bismuth based ternary oxide photocatalysts are of considerable interest in
+photoelectrochemical water splitting. Yet these oxides are highly stable in
+different environment, their relative inertness limits the available synthesis
+routes to obtain desired stoichiometry on the final product. This report
+describes a method to prepare barium bismuth niobate (specifically, Ba2(BiNb)O6
+and Ba2Bi1.4Nb0.6 O6) target by sintering a mixture of individual oxides and
+successfully fabricate desired barium bismuth niobate thin film on TCO
+substrate. The surface morphology, physical, and chemical properties of thin
+film were systematically investigated. Compositional uniformity was obtained by
+sputtering in oxygen argon plasma environment and higher photocatalytic
+activities were observed after subsequent surface treatments. Sodium fluoride
+surface treatment further enhanced the photocurrent density and improved
+electrode stability against corrosion. This work further suggests a viable
+approach to improve the PEC performance of sputtered barium bismuth niobate by
+modulating their fundamental energy states.",1911.12188v1
+2019-11-27,Study of RF Sputtered Antimony Alloyed Bismuth Vanadium Oxide (Sb:BiVO4) Thin Films for Enhanced Photoelectrochemical (PEC) performance from Bandgap Modulation to Thickness Optimization,"Monoclinic scheelite bismuth vanadate (BiVO4) is a promising photoanode for
+water splitting yet the PEC performance is limited due to its relatively higher
+(2.4 eV) band gap. Here, we successfully decreased its the band gap to 1.72 eV
+by controlled antimony alloying. Low bandgap antimony alloyed bismuth vanadium
+oxide (Sb:BiVO4) thin film was prepared by RF sputtering of high purity
+homemade target, fabricated by solid-state reaction using a mixture of Sb2O3,
+Bi2O3, and V2O5 powders with desired stoichiometric ratios. Several growth
+parameters, powder crystallography, post-deposition effects, and surface
+treatments, thickness dependence, effect of electrolytes on photocorrosion were
+studied along with its optical and electrochemical characterization. We
+discovered that Sb:BiVO4 is a direct band gap material in the visible light
+range (1.72 eV) and a valence band position suitable for driving water
+oxidation reaction under illumination. Furthermore, hole diffusion length is
+increased with antimony alloying and achieved optimum thickness of 400 nm for
+higher photocurrent. The controllably prepared Sb:BiVO4 particles are having
+the sizes of 10-15 nm in room temperature deposition and can be grown up to 0.5
+microns under air annealing.",1911.12191v1
+2019-12-04,Optical phased arrays for LIDAR: beam steering via tunable plasmonic metasurfaces,"Controlling the phase and amplitude of light emitted by the elements (i.e.,
+pixels) of an optical phased array is of paramount importance to realizing
+dynamic beam steering for LIDAR applications. In this paper, we propose a
+plasmonic pixel composed of a metallic nanoantenna covered by a thin oxide
+layer, and a conductive oxide, e.g., ITO, for use in a reflectarray
+metasurface. By considering voltage biasing of the nanoantenna via metallic
+connectors, and exploiting the carrier refraction effect in the
+metal-oxide-semiconductor capacitor in the accumulation and depletion regions,
+our simulations predict control of the reflection coefficient phase over a
+range $>330^{\circ}$ with a nearly constant magnitude. We discuss the physical
+mechanism underlying the optical response, the effect of the connectors, and
+propose strategies to maximize the magnitude of the reflection coefficient and
+to achieve dual-band operation. The suitability of our plasmonic pixel design
+for beam steering in LIDAR is demonstrated via 3D-FDTD simulations.",1912.02275v1
+2019-12-17,Physical properties and device applications of graphene oxide,"Graphene oxide (GO), the functionalized graphene with oxygenated groups
+(mainly epoxy and hydroxyl), has attracted resurgent interests in the past
+decade owing to its large surface area, superior physical and chemical
+properties, and easy composition with other materials via surface functional
+groups. Usually, GO is used as an important raw material for mass production of
+graphene via reduction. However, under different conditions, the coverage,
+types, and arrangements of oxygen-containing groups in GO can be varied, which
+give rise to excellent and controllable physical properties, such as tunable
+electronic and mechanical properties depending closely on oxidation degree,
+suppressed thermal conductivity, optical transparency and fluorescence, and
+nonlinear optical properties. Based on these outstanding properties, many
+electronic, optical, optoelectronic, and thermoelectric devices with high
+performance can be achieved on the basis of GO. Here we present a comprehensive
+review on recent progress of GO, focusing on the atomic structures, fundamental
+physical properties, and related device applications, including transparent and
+flexible conductors, field-effect transistors, electrical and optical sensors,
+fluorescence quenchers, optical limiters and absorbers, surface enhanced Raman
+scattering detectors, solar cells, light-emitting diodes, and thermal
+rectifiers.",1912.07956v1
+2019-12-18,Schottky barrier induced asymmetry in the negative differential resistance response of Nb/NbOx/Pt cross-point devices,"The negative differential resistance (NDR) response of Nb/NbOx/Pt cross-point
+devices is shown to have a polarity dependence due to the effect of the
+metal/oxide Schottky barriers on the contact resistance. Three distinct
+responses are observed under opposite polarity testing: bipolar S-type NDR,
+bipolar snap-back NDR, and combined S-type and snap-back NDR, depending on the
+stoichiometry of the oxide film and device area. In-situ thermoreflectance
+imaging is used to show that these NDR responses are associated with strong
+current localisation, thereby justifying the use of a previously developed
+two-zone, core shell thermal model of the device. The observed polarity
+dependent NDR responses, and their dependence on stoichiometry and area are
+then explained by extending this model to include the effect of the polarity
+dependent contact resistance. This study provides an improved understanding of
+the NDR response of metal/oxide/metal structures and informs the engineering of
+devices for neuromorphic computing and non-volatile memory applications.",1912.08371v1
+2019-12-20,Operando XANES from first-principles and its application to iridium oxide,"Efficient electro-catalytic water-splitting technologies require suitable
+catalysts for the oxygen evolution reaction (OER). The development of novel
+catalysts could benefit from the achievement of a complete understanding of the
+reaction mechanism on iridium oxide (IrO$_2$), an active catalyst material that
+is, however, too scarce for large-scale applications. Considerable insight has
+already been provided by \emph{operando} X-ray absorption near-edge structure
+(XANES) experiments, which paved the way towards an atomistic description of
+the catalyst's evolution in a working environment. We combine here
+first-principles simulations augmented with a continuum description of the
+solvent and electrolyte to investigate the electrochemical stability of various
+IrO$_2$ interfaces and to predict the XANES cross-section for selected
+terminations under realistic conditions of applied potential. The comparison of
+computed O K-edge XANES spectra to corresponding experiments supports the
+formation of electron-deficient surface oxygen species in the OER-relevant
+voltage regime. Furthermore, surface hydroxyl groups that are found to be
+stable up to $\sim$1 V are suggested to be progressively oxidized at larger
+potentials, giving rise to a shift in the Ir L$_3$-edge cross-section that
+qualitatively agrees with measurements.",1912.09769v1
+2020-05-04,On the origin of the premature breakdown of thermal oxide on 3C-SiC probed by electrical scanning probe microscopy,"The dielectric breakdown (BD) of thermal oxide (SiO2) grown on cubic silicon
+carbide (3C-SiC) was investigated comparing the electrical behavior of
+macroscopic metal-oxidesemiconductor (MOS) capacitors with nanoscale current
+and capacitance mapping using conductive atomic force (C-AFM) and scanning
+capacitance microscopy (SCM). Spatially resolved statistics of the oxide BD
+events by C-AFM revealed that the extrinsic premature BD is correlated to the
+presence of peculiar extended defects, the anti-phase boundaries (APBs), in the
+3C-SiC layer. SCM analyses showed a larger carrier density at the stacking
+faults (SFs) the 3C-SiC, that can be explained by a locally enhanced density of
+states in the conduction band. On the other hand, a local increase of minority
+carriers concentration was deduced for APBs, indicating that they behave as
+conducting defects having also the possibility to trap positive charges. The
+results were explained with the local electric field enhancement in
+correspondence of positively charged defects.",2005.01290v1
+2020-05-15,Moderate bandgap and high carrier mobility simultaneously realized in bilayer silicene by oxidation,"Semiconductors simultaneously possessing high carrier mobility, moderate
+bandgap, and ambient environment stability are so important for the modern
+industry, and Si-based semiconducting materials can match well with the
+previous silicon based electronic components. Thus, searching for such Si-based
+semiconductors has been one hot project due to the lack of them nowadays. Here,
+with the help of density functional theory, we found that the oxidized bilayer
+silicene exhibits high carrier mobility with a moderate direct bandgap of 1.02
+eV. The high carrier mobility is caused by the remaining of big pi bond, and
+the moderate bandgap is opened by the saturation of dangling Si 3p bonds.
+Originated from the formation of strong Si-O and Si-Si bonds, the sample
+exhibits strong thermodynamic and dynamical stabilities. Our work indicates
+that the oxidized bilayer silicene has many potential applications in modern
+electronic fields.",2005.07517v1
+2020-05-19,Density fitting in periodic systems: application to TDHF in diamond and oxides,"A robust density fitting method for calculating Coulomb matrix elements over
+Bloch functions based on calculation of two- and three-center matrix elements
+of the Ewald potential is described and implemented in a Gaussian orbital basis
+in the Exciton code. The method is tested by comparing Coulomb and exchange
+energies from density fitting to corresponding energies from SCF HF
+calculations for diamond, magnesium oxide and bulk Ne. Density fitting
+coefficients from the robust method are compared to coefficients from a
+variational method applied to wave function orbital products in bulk Ne. Four
+center Coulomb matrix elements from density fitting are applied to time
+dependent Hartree-Fock (TDHF) calculations in diamond, magnesium oxide and
+anatase and rutile polytypes of titanium dioxide. Shifting virtual states
+downwards uniformly relative to occupied states and scaling the electron-hole
+attraction term in the TDHF Hamiltonian by 0.4 yields good agreement with
+either experiment and/or Bethe-Salpeter equation calculations. This approach
+mirrors similar 'scissors' adjustments of occupied and virtual states and
+introduction of a scaled electron-hole attraction term in some time dependent
+DFT calculations.",2005.09291v1
+2020-06-17,On the microscopic origin of reversible and irreversible reactions of LiNixCoyMnx cathode materials: Ni-O hybrid bond formation vs. cationic and anionic redox,"Energy density limitations of layered oxides with different Ni contents,
+i.e., of the conventional cathode materials in Li-ion batteries, are
+investigated across the first discharge cycle using advanced spectroscopy and
+state-of-the-art diffraction. For the first time unambiguous experimental
+evidence is provided, that redox reactions in NCMs proceed via a reversible
+oxidation of Ni and a hybridization with O, and not, as widely assumed, via
+pure cationic or more recently discussed, pure anionic redox processes. Once
+Ni-O hybrid states are formed, the sites cannot be further oxidized. Instead,
+irreversible reactions set in which lead to a structural collapse and thus, the
+lack of ionic Ni limits the reversible capacity. Moreover, the degree of
+hybridization, which varies with the Ni content, triggers the electronic
+structure and the operation potential of the cathodes. With an increasing
+amount of Ni, the covalent character of the materials increases and the
+potential decreases.",2006.09964v1
+2020-08-27,Mapping nanoscale charge states and phase domains with quantitative hyperspectral coherent diffractive imaging spectroscopy,"The critical properties of functional materials and nanoscale devices often
+originate from the coexistence of different thermodynamic phases and / or
+oxidization states, but sample makeup is seldom completely known a priori.
+Coherent diffractive imaging (CDI) provides the spatial resolution needed to
+observe nanoscale coexistence while returning the full amplitude and phase
+information of an object, but to date lacks the spectral information necessary
+for composition identification. Here we demonstrate CDI spectroscopy (CDIS),
+acquiring images of the prototypical quantum material vanadium oxide across the
+vanadium L2,3 and oxygen K X-ray absorption edges with nanometer scale
+resolution. Using the hyperspectral X-ray image we show coexistence of multiple
+oxidization states and phases in a single sample and extract the full complex
+refractive index of V2O5 and the monoclinic insulating and rutile conducting
+phases of VO2. These results constrain the role of hidden phases in the
+insulator-to-metal transition in VO2.",2008.11992v1
+2020-09-09,An Experimentally Driven Automated Machine Learned lnter-Atomic Potential for a Refractory Oxide,"Understanding the structure and properties of refractory oxides are critical
+for high temperature applications. In this work, a combined experimental and
+simulation approach uses an automated closed loop via an active-learner, which
+is initialized by X-ray and neutron diffraction measurements, and sequentially
+improves a machine-learning model until the experimentally predetermined phase
+space is covered. A multi-phase potential is generated for a canonical example
+of the archetypal refractory oxide, HfO2, by drawing a minimum number of
+training configurations from room temperature to the liquid state at ~2900oC.
+The method significantly reduces model development time and human effort.",2009.04045v1
+2020-09-24,Probing redox potential for Iron sulfur clusters in photosystem I,"Photosystem I is a light-driven electron transfer device. Available X-ray
+crystal structure from Thermosynechococcus elongatus, showed that electron
+transfer pathways consist of two nearly symmetric branches of cofactors
+converging at the first iron sulfur cluster FX, which is followed by two
+terminal iron sulfur clusters FA and FB. Experiments have shown that Fx has
+lower oxidation potential than FA and FB, which facilitate the electron
+transfer reaction. Here, we use Density Functional Theory and Multi-Conformer
+Continuum Electrostatics to explain the differences in the midpoint Em
+potentials of the Fx, FA and FB clusters. Our calculations show that Fx has the
+lowest oxidation potential compared to FA and FB due strong pair-wise
+electrostatic interactions with surrounding residues. These interactions are
+shown to dominated by the bridging sulfurs and cysteine ligands, which may be
+attributed to the shorter average bond distances between the oxidized Fe ion
+and ligating sulfurs for FX compared to FA and FB. Moreover, the electrostatic
+repulsion between the 4Fe-4S clusters and the positive potential of the
+backbone atoms is least for FX compared to both of FA and FB. These results
+agree with the experimental measurements from the redox titrations of
+low-temperature EPR signals and of room temperature recombination kinetics.",2009.11681v1
+2020-10-06,Identification of Li$_{\text{Ni}}$ and V$_{\text{Ni}}$ acceptor levels in doped nickel oxide,"Nickel oxide, in particular in its doped, semiconducting form, is an
+important component of several optoelectronic devices. Doping NiO is commonly
+achieved either by incorporation of lithium, which readily occupies Ni sites
+substitutionally, producing the Li$_{\text{Ni}}$ acceptor, or by supplying
+reactive oxygen species during NiO film deposition, which leads to the
+formation of Ni vacancies (V$_{\mathrm{Ni}}$). However, the energetic position
+of these acceptors in the NiO band gap has not been experimentally determined
+until today. In this work, we close this knowledge gap by studying rectifying
+n$^{++}$p heterojunctions of NiO on top of fluorine-doped tin oxide. These
+structures show sufficient rectification to perform electric characterization
+by defect spectroscopic techniques, specifically capacitance-voltage and
+thermal admittance spectroscopy. Using these methods, the (0/-) charge
+transition levels are determined to be 190meV and 409meV above the valence band
+edge for the Li$_{\text{Ni}}$ and the V$_{\text{Ni}}$ acceptor, respectively.",2010.02694v1
+2020-11-25,Effect of pseudo-cubic (111)-oriented orthorhombic substrate facets on perovskite oxide thin film synthesis,"Strain engineering with different substrate facets is promising for tuning
+functional properties of thin film perovskite oxides. By choice of facet,
+different surface symmetries and chemical bond directions for epitaxial
+interfaces can be tailored. Here, preparation of well-defined pseudo-cubic
+(111)-oriented orthorhombic substrates of DyScO3 , GdScO3 , and NdGaO3 is
+reported. The choice of orthorhombic facet, (011)o or (101)o , both
+corresponding to pseudo-cubic (111)pc , gives vicinal surfaces with single or
+double (111pc layer terrace step heights, respectively, impacting subsequent
+thin film growth. Orthorhombic LaFeO3 epitaxy on the (101)o facet reveals a
+distinction between alternating (111)pc layers, both during and after growth.
+The observed differences are explained based on the oxygen octahedral tilt
+pattern relative to the two orthorhombic (111)pc surfaces. This robust
+structural detail in the orthorhombic perovskite oxides enables utilisation of
+different (111)pc facets for property engineering, through polyhedral
+connectivity control and cation coordination at epitaxial interfaces.",2011.12874v1
+2021-03-09,The Laser-Diode Heated Floating Zone Method for Automated Optimal Synthesis of Refractory Oxides and Alloys,"We perform an experimental investigation of the synthesis of complex
+materials using the Laser-diode heated floating zone method (L-FZ). We will
+briefly introduce the Infrared-heated floating zone method of bulk crystal
+growth and then delve into recent advances in using a Laser-diode heated
+floating zone method. We demonstrate L-FZ for the growth of large high-quality
+single crystalline samples of of the n=2 Ruddlesden-Popper homologous series
+$RE_2SrAl_2O_7$, RE = Nd, Sm, Eu, Gd, Tb, Dy with physically interesting
+properties (e.g spin-ice) as well as the incongruently melting
+stuffed-tridymite type oxide $BaCoSiO_4$. We conclude with a summary of the
+results and future research directions in automating crystal growth, which will
+open access into the synthesis and characterization of previously unstudied
+class of materials such as refractory complex oxides and alloys.",2103.05587v1
+2021-03-11,Highly confined phonon polaritons in monolayers of oxide perovskites,"Two-dimensional (2D) materials are able to strongly confine light hybridized
+with collective excitations of atoms, enabling electric-field enhancements and
+novel spectroscopic applications. Recently, freestanding monolayers of oxide
+perovskites have been synthesized, which possess highly infrared-active phonon
+modes and a complex interplay of competing interactions. In this study, we
+evaluate central figures of merit for phonon polaritons in the tetragonal
+phases of the 2D perovskites SrTiO$_3$, KTaO$_3$, and LiNbO$_3$, using density
+functional theory calculations. Specifically, we compute the 2D
+phonon-polariton dispersions, the propagation-quality, confinement, and
+deceleration factors, and we show that they are comparable to those found in
+the prototypical 2D dielectric hexagonal boron nitride. Our results suggest
+that monolayers of oxide perovskites are promising candidates for polaritonic
+platforms in the terahertz spectral range that enable possibilites to control
+complex phases of matter through strongly enhanced electromagnetic fields.",2103.06949v1
+2021-03-17,Raman Signal Reveals the Rhombohedral Crystallographic Structure in Ultra-thin Layers of Bismuth Thermally Evaporated on Amorphous Substrate,"Under the challenge of growing a single bilayer of Bi oriented in the (111)
+crystallographic direction over amorphous substrates, we have studied different
+thicknesses of Bi thermally evaporated onto silicon oxide in order to shed
+light on the dominant atomic structures and their oxidation. We have employed
+atomic force microscope, X-ray diffraction, and scanning electron microscope
+approaches to demonstrate that Bi is crystalline and oriented in the (111)
+direction for thicknesses over 20 nm. Surprisingly, Raman spectroscopy
+indicates that the rhombohedral structure is preserved even for ultra-thin
+layers of Bi, down to $\sim 5$ nm. Moreover, the signals also reveal that
+bismuth films exposed to ambient conditions do not suffer major surface
+oxidation.",2103.09400v1
+2021-04-13,"Faraday law, oxidation numbers, and ionic conductivity: The role of topology","Faraday's experiment measures -- within a modern view -- the charge
+adiabatically transported over a macroscopic distance by a given nuclear
+species in insulating liquids: the reason why it is integer is deeply rooted in
+topology. Whole numbers enter chemistry in a different form: atomic oxidation
+states. They are not directly measurable, and are determined instead from an
+agreed set of rules. Insulating liquids are a remarkable exception: Faraday's
+experiment indeed measures the oxidation numbers of each dissociated component
+in the liquid phase, whose topological values are unambiguous. Ionic
+conductivity in insulating liquids is expressed in terms of the autocorrelation
+function of the fluctuating charge current at a given temperature in zero
+electric field; topology plays a major role in this important observable as
+well. The existing literature deals with the above issues by adopting the
+independent-electron framework; here I provide the many-body generalization of
+all the above findings, which furthermore allows for compact and very
+transparent notations and formulas.",2104.06026v2
+2021-04-16,The Millimeter-Wave Spectrum of Doubly Deuterated Propylene Oxide CH$_3$CHCD$_2$O,"Spectra of doubly deuterated propylene oxide, CH$_3$CHCD$_2$O, were recorded
+in the millimeter-wave spectral region up to 330 GHz utilizing a 2f frequency
+modulated Terahertz spectrometer. Rotational and centrifugal distortion
+constants and tunneling parameters for the description of the internal rotation
+of the methyl group were retrieved. The software XIAM was used to describe the
+A-E tunneling splitting with a frequency uncertainty of 82 kHz. Molecular
+parameters derived from our measurements are complemented by quantum chemical
+anharmonic frequency calculations on the B3LYP/augcc-pVTZ level of theory. In
+addition, the barrier height to internal rotation of the methyl group,V3, was
+derived experimentally and found to slightly differ from the value reported for
+the main isotopologue. In view of astrophysical observations we provide
+accurate line lists to search for doubly deuterated propylene oxide in space.
+Furthermore, we deliver improved molecular parameters to further investigate
+the properties of a simple chiral molecule possessing internal large amplitude
+motions.",2104.08151v1
+2021-04-27,Percolation of Ion-Irradiation-Induced Disorder in Complex Oxide Interfaces,"Mastery of order-disorder processes in highly non-equilibrium nanostructured
+oxides has significant implications for the development of emerging energy
+technologies. However, we are presently limited in our ability to quantify and
+harness these processes at high spatial, chemical, and temporal resolution,
+particularly in extreme environments. Here we describe the percolation of
+disorder at the model oxide interface LaMnO$_3$ / SrTiO$_3$, which we visualize
+during in situ ion irradiation in the transmission electron microscope. We
+observe the formation of a network of disorder during the initial stages of ion
+irradiation and track the global progression of the system to full disorder. We
+couple these measurements with detailed structural and chemical probes,
+examining possible underlying defect mechanisms responsible for this unique
+percolative behavior.",2104.13272v1
+2021-04-28,Effective reduction of PdCoO2 thin films via hydrogenation and sign tunable anomalous Hall effect,"PdCoO2 , belonging to a family of triangular oxides called delafossite, is
+one of the most conducting oxides. Its in-plane conductivity is comparable to
+those of the best metals, and exhibits hydrodynamic electronic transport with
+extremely long mean free path at cryogenic temperatures. Nonetheless, it is
+nonmagnetic despite the presence of the cobalt ion. Here, we show that a mild
+hydrogenation process reduces PdCoO2 thin films to an atomically-mixed alloy of
+PdCo with strong out-of-plane ferromagnetism and sign-tunable anomalous Hall
+effect. Considering that many other compounds remain little affected under a
+similar hydrogenation condition, this discovery may provide a route to creating
+novel spintronic heterostructures combining strong ferromagnetism, involving
+oxides and other functional materials.",2104.13536v1
+2021-05-04,Electron-Phonon Coupling and Electron-Phonon Scattering in SrVO$_3$,"Understanding the physics of strongly correlated electronic systems has been
+a central issue in condensed matter physics for decades. In transition metal
+oxides, strong correlations characteristic of narrow $d$ bands is at the origin
+of such remarkable properties as the Mott gap opening, enhanced effective mass,
+and anomalous vibronic coupling, to mention a few. SrVO$_3$, with V$^{4+}$ in a
+$3d^1$ electronic configuration is the simplest example of a 3D correlated
+metallic electronic system. Here, we focus on the observation of a (roughly)
+quadratic temperature dependence of the inverse electron mobility of this
+seemingly simple system, which is an intriguing property shared by other
+metallic oxides. The systematic analysis of electronic transport in SrVO$_3$
+thin films discloses the limitations of the simplest picture of e-e
+correlations in a Fermi liquid; instead, we show that the quasi-2D topology of
+the Fermi surface and a strong electron-phonon coupling, contributing to dress
+carriers with a phonon cloud, play a pivotal role on the reported electron
+spectroscopic, optical, thermodynamic and transport data. The picture that
+emerges is not restricted to SrVO$_3$ but can be shared with other $3d$ and
+$4d$ metallic oxides.",2105.01579v1
+2021-05-06,Balancing orbital effects and onsite Coulomb repulsion through Na modulations in NaxVO2,"Vanadium oxides have been highly attractive for over half a century since the
+discovery of the metal insulator transition near room temperatures. Here NaxVO2
+is studied through a systematic comparison with other layered sodium metal
+oxides with early 3d transition metals, first disclosing a unified evolution
+pattern of Na density waves through in situ XRD analysis. Combining ab-initio
+simulations and theoretical modelings, a sodium-modulated Peierls-like
+transition mechanism is then proposed for the bonding formation of metal ion
+dimers. More importantly, the unique trimer structure in NaxVO2 is shown to be
+very sensitive to the onsite Coulomb repulsion value, suggesting a delicate
+balance between strong electronic correlations and orbital effects that can be
+precisely modulated by both Na compositions and atomic stackings. This unveils
+a unique opportunity to design strongly correlated materials with tailored
+electronic transitions through electrochemical modulations and crystallographic
+designs, to elegantly balance various competition effects. We think the
+understanding will also help further elucidate complicated electronic behaviors
+in other vanadium oxide systems.",2105.02416v1
+2021-05-21,Novel ion-doped mesoporous glasses for bone tissue engineering: Study of their strctural characteristics influenced by the presence of phosphorous oxide,"Ion-doped binary SiO2-CaO and ternary SiO2-CaO-P2O5 mesoporous bioactive
+glasses were synthesised and characterised to evaluate the influence of P2O5 in
+the glass network structure. Strontium, copper and cobalt oxides in a
+proportion of 0.8 mol% were selected as dopants because the osteogenic and
+angiogenic properties reported for these elements. Although the four glass
+compositions investigated presented analogous textural properties, TEM analysis
+revealed that the structure of those containing P2O5 exhibited an increased
+ordered mesoporosity. Furthermore, 29Si NMR revealed that the incorporation of
+P2O5 increased the network connectivity and that this compound captured the
+Sr2+, Cu2+ and Co2+ ions preventing them to behave as modifiers of the silica
+network. In addition, 31P NMR results revealed that the nature of the cation
+directly influences the characteristics of the phosphate clusters. In this
+study, we have proven that phosphorous oxide entraps doping-metallic ions,
+granting these glasses with a greater mesopores order.",2105.10222v1
+2021-06-11,Redox Active Cerium Oxide Nanoparticles: Current Status and Burning Issues,"Research on cerium oxide nanoparticles (nanoceria) has captivated the
+scientific community due to their unique physical and chemical properties, such
+as redox activity and oxygen buffering capacity, which made them available for
+many technical applications, including biomedical applications. The redox
+mimetic antioxidant properties of nanoceria have been effective in the
+treatment of many diseases caused by reactive oxygen species (ROS) and reactive
+nitrogen species. The mechanism of ROS scavenging activity of nanoceria is
+still elusive, and its redox activity is controversial due to mixed reports in
+the literature showing pro-oxidant and antioxidant activity. In lieu of its
+current research interest, it is critical to understand the behaviour of
+nanoceria in the biological environment and provide answers to some of the
+critical and open issues. This review critically analyses the status of
+research on the application of nanoceria to treat diseases caused by ROS. It
+reviews the proposed mechanism of action and shows the effect of surface
+coatings on its redox activity. It also discusses some of the crucial issues in
+deciphering the mechanism and redox activity of nanoceria and suggests areas of
+future research.",2106.06473v1
+2021-06-12,RF surface resistance tuning of superconducting niobium via thermal diffusion of native oxide,"Recently, Nb superconducting radio frequency cavities vacuum heat treated
+between 300-400 C for a few hours have exhibited very high quality factors
+(~5x10^10 at 2.0 K). New secondary ion mass spectrometry measurements of O, N
+and C show this enhancement in RF surface conductivity is primarily associated
+with interstitial O alloying via dissolution and diffusion of the native oxide.
+We use a theory of oxide decomposition and O diffusion to quantify previously
+unknown parameters crucial in modeling this process. RF measurements of a
+vacuum heat treated Nb superconducting radio frequency cavity confirm the
+minimized surface resistance (higher Q0) previously expected only from 800 C
+diffusive alloying with N.",2106.06647v2
+2021-06-14,Semi-Dirac and Weyl Fermions in Transition Metal Oxides,"We show that a class of compounds with $I$4/$mcm$ crystalline symmetry hosts
+three-dimensional semi-Dirac fermions. Unlike the known two-dimensional
+semi-Dirac points, the degeneracy of these three-dimensional semi-Dirac points
+is not lifted by spin-orbit coupling due to the protection by a nonsymmorphic
+symmetry -- screw rotation in the $a-b$ plane and a translation along the $c$
+axis. This crystalline symmetry is found in tetragonal perovskite oxides,
+realizable in thin films by epitaxial strain that results in
+a$^0$a$^0$c$^-$-type octahedral rotation. Interestingly, with broken
+time-reversal symmetry, two pairs of Weyl points emerge from the semi-Dirac
+points within the Brillouin zone, and an additional lattice distortion leads to
+enhanced intrinsic anomalous Hall effect. The ability to tune the Berry phase
+by epitaxial strain can be useful in novel oxide-based electronic devices.",2106.07793v2
+2021-06-23,Charged Oxygen Vacancy Induced Ferroelectric Structure Transition in Hafnium Oxide,"The discovery of ferroelectric HfO2 in thin films and more recently in bulk
+is an important breakthrough because of its silicon-compatibility and
+unexpectedly persistent polarization at low dimensions, but the origin of its
+ferroelectricity is still under debate. The stabilization of the metastable
+polar orthorhombic phase was often considered as the cumulative result of
+various extrinsic factors such as stress, grain boundary, and oxygen vacancies
+as well as phase transition kinetics during the annealing process. We propose a
+novel mechanism to stabilize the polar orthorhombic phase over the nonpolar
+monoclinic phase that is the bulk ground state. Our first-principles
+calculations demonstrate that the doubly positively charged oxygen vacancy, an
+overlooked defect but commonly presented in binary oxides, is critical for the
+stabilization of ferroelectric phase. The charge state of oxygen vacancy serves
+as a new degree of freedom to control the thermodynamic stability of competing
+phases of wide-band-gap oxides.",2106.12159v1
+2021-06-26,High Infrared Reflectance Modulation in VO2 Films Synthesized on Glass and ITO coated Glass substrates using Atmospheric Oxidation of Vanadium,"Vanadium Dioxide (VO2) is a strongly correlated material, which exhibits
+insulator to metal transition at ~68 C along with large resistivity and
+infrared optical reflectance modulation. In this work, we use atmospheric
+pressure thermal oxidation of Vanadium to synthesize VO2 films on glass and ITO
+coated glass substrates. With the optimized short oxidation durations of 2 min
+and 4 min, the synthesized VO2 film shows high optical reflectance switching in
+long-wavelength infrared on glass substrates and mid-wavelength infrared on ITO
+coated glass substrates, respectively. Peak reflectance switching values of
+~76% and ~79% are obtained on the respective substrates, which are among the
+highest reported values. Using the reflectance data, we extract VO2 complex
+refractive index in infrared wavelengths, in both the insulating and metallic
+phases. The extracted refractive index shows good agreement with VO2
+synthesized using other methods. This demonstration of high optical reflectance
+switching in VO2 thin films, grown on low cost glass and ITO coated glass
+substrates, using a simple low thermal budget process will aid in enhancing VO2
+applications in the optical domain.",2106.14006v1
+2021-07-04,Theoretical Prediction of Heterogeneous Integration of Dissimilar Semiconductor with Various Ultra-Thin Oxides and 2D Materials,"In this paper, we have built a numerical p-n Si/GaAs heterojunction model
+using a quantum-mechanical tunneling theory with various quantum tunneling
+interfacial materials including two-dimensional semiconductors such as
+hexagonal boron nitride (h-BN) and graphene and ALD-enabled oxide materials
+such as HfO2, Al2O3, and SiO2. Their tunneling efficiencies and tunneling
+current with different thicknesses were systematically calculated and compared.
+Multiphysics modeling was used with the aforementioned tunneling interfacial
+materials to analyze changes in strain under different temperature conditions.
+Considering the transport properties and thermal-induced strain analysis, Al2O3
+among three oxide materials and graphene in 2D materials are favorable material
+choices that offer the highest heterojunction quality. Overall, our results
+offer the viable route to guide the selection of quantum tunneling materials
+for myriad possible combinations of new heterostructures that can be obtained
+via remote epitaxy and the UO method.",2107.01625v1
+2021-08-26,Orbital Occupancy and Hybridization in Strained SrVO$_3$ Epitaxial Films,"Oxygen packaging in transition metal oxides determines the metal-oxygen
+hybridization and electronic occupation at metal orbitals. Strontium vanadate
+(SrVO$_3$), having a single electron in a $3d$ orbital, is thought to be the
+simplest example of strongly correlated metallic oxides. Here, we determine the
+effects of epitaxial strain on the electronic properties of SrVO$_3$ thin
+films, where the metal-oxide sublattice is corner-connected. Using x-ray
+absorption and x-ray linear dichroism at the V $L_{2,3}$ and O $K$-edges, it is
+observed that tensile or compressive epitaxial strain change the hierarchy of
+orbitals within the $t_{2g}$ and $e_g$ manifolds. Data show a remarkable
+$2p-3d$ hybridization, as well as a strain-induced reordering of the V
+$3d$($t_{2g}$, $e_g$) orbitals. The latter is itself accompanied by a
+consequent change of hybridization that modulates the hybrid $\pi^*$ and
+$\sigma^*$ orbitals and the carrier population at the metal ions, challenging a
+rigid band picture.",2108.11718v1
+2021-08-27,Low-temperature emergent neuromorphic networks with correlated oxide devices,"Neuromorphic computing which aims to mimic the collective and emergent
+behavior of the brain's neurons, synapses, axons, dendrites offers an
+intriguing, potentially disruptive solution to society's ever-growing
+computational needs. Although much progress has been made in designing circuit
+elements that mimic the behavior of neurons and synapses, challenges remain in
+designing networks of elements that feature a collective response behavior. We
+present simulations of networks of circuits and devices based on
+superconducting and Mott-insulating oxides that display a multiplicity of
+emergent states that depend on the spatial configuration of the network. Our
+proposed network designs are based on experimentally known ways of tuning the
+properties of these oxides using light ions. We show how neuronal and synaptic
+behavior can be achieved with arrays of superconducting Josephson junction
+loops, all within the same device. We also show how a multiplicity of synaptic
+states could be achieved by designing arrays of devices based on hydrogenated
+rare-earth nickelates. Together, our results demonstrate a new research
+platform that utilizes the collective macroscopic properties of quantum
+materials to mimic the emergent behavior found in biological systems.",2108.12454v1
+2021-09-01,Disorder-induced ordering in gallium oxide polymorphs,"Polymorphs are common in nature and can be stabilized by applying external
+pressure in materials. The pressure/strain can also be induced by the gradually
+accumulated radiation disorder. However, in semiconductors, the radiation
+disorder accumulation typically results in the amorphization instead of
+engaging polymorphism. By studying these phenomena in gallium oxide we found
+that the amorphization may be prominently suppressed by the monoclinic to
+orthorhombic phase transition. Utilizing this discovery, a highly oriented
+single-phase orthorhombic film on the top of the monoclinic gallium oxide
+substrate was fabricated. Exploring this system, a novel mode of a lateral
+polymorphic regrowth, not previously observed in solids, was detected. In
+combination, these data envisage a new direction of research on polymorphs in
+Ga2O3 and, potentially, for similar polymorphic families in other materials.",2109.00242v2
+2021-08-30,Multi-charge Transfer from Photodoped ITO Nanocrystals,"Metal oxide nanocrystals are emerging as extremely versatile material for
+addressing many of the current challenging demands of energy-conversion
+technology. Being able to exploit their full potential is not only an advantage
+but also a scientific and economic ambition for a more sustainable energy
+technology. In this direction, photodoping of metal oxide nanocrystals is a
+very notable process that allows accumulating multiple charge carriers per
+nanocrystals after light absorption. The reactivity of the photodoped electrons
+is currently the subject of an intense study. In this context, the possibility
+to efficiently extract the stored electrons could be beneficial for numerous
+processes, from photoconversion and sunlight energy storage, to photocatalysis
+and photoelectrochemistry. In this work we provide, via oxidative titration and
+optical spectroscopy, evidence for multi-electron transfer processes from
+photodoped Sn:In2O3 nanocrystals to a widely employed organic electron acceptor
+(F4TCNQ). The results of this study disclose the potential of photodoped
+electrons to drive chemical reactions involving more than one electron at a
+time.",2109.00499v1
+2021-09-07,Luminescence of localized states in oxidized and fluorinated silica glass,"The photoluminescence of oxidized and fluorinated nominally pure silica
+glasses, which have good optical transparency in the optical gap, has been
+investigated under excitation by excimer lasers. The data are compared with the
+data for chlorinated silica glass, as well as glass containing OH. The
+excitation of localized states provides the release and capture of charge
+carriers, despite the low absorption coefficient. Holes are self-trapped. The
+recombination in the thermally activated or tunnel process creates luminescence
+of oxygen-deficient centers. It is concluded that oxidation and fluorination do
+not change the concentration of localized states, but they change the
+electronic transitions of localized states to higher energies. In type III
+glass with a high OH content, luminescence is suppressed by the presence of
+hydrogen and appears after irradiation with photons of 7.9 eV of the F2 laser.
+This can also be the evidence of existing of localized states even in such
+glasses.",2109.03012v1
+2021-09-11,Surface Van Hove Singularity Enabled Efficient Catalysis: The Cases of CO Oxidation and Hydrogen Evolution Reactions,"Surface Van Hove singularity (SVHS), defined as the surface states near the
+Fermi level (EF) in low-dimensional systems, triggers exciting physical
+phenomena distinct from bulk. We herein explore theoretically the potential
+role of SVHS in catalysis taking CO oxidation reaction as prototype over
+graphene/Ca2N (Gra/Ca2N) heterojunction and Pt2HgSe3 (001) surface. It is
+demonstrated that both systems with SVHS could serve as an electron bath to
+promote O2 adsorption and subsequent CO oxidation with low energy barriers of
+0.2 ~ 0.6 eV for Gra/Ca2N and Pt2HgSe3 (001) surface. Importantly, the
+catalytically active sites associated with SVHS are well-defined and uniformly
+distributed over the whole surface plane, which is superior to the commonly
+adopted defect or doping strategy, and further the chemical reactivity of SVHS
+also can be tuned easily via adjusting its position with respect to EF. Our
+study demonstrates the enabling power of SVHS, and provides novel physical
+insights into the promising potential role of VHS in designing high-efficiency
+catalysts.",2109.05209v1
+2021-09-13,An Analytical 2-D Model of Triple Metal Double Gate Graded Channel Junctionless MOSFET with Hetero-dielectric Gate Oxide Stack,"In this paper, a two-dimensional analytical model of a laterally
+graded-channel triple-metal double-gate Junctionless Field Effect Transistor
+with hetero dielectric gate oxide stack consisting of SiO$_2$ and HfO$_2$ is
+derived. The model illustrates higher drive current and better performance
+against hazardous SCEs and HCEs in below 30 nm regime. Parabolic approximation
+method is used here to construct channel potentials and electric fields by
+solving 2-D Poisson's equation with applicable boundary conditions. The basic
+central and surface potentials as well as central and surface electric fields
+are being illustrated, Threshold voltage, DIBL, sub-threshold swing (SS) and a
+compact current model have also been deduced. These parameters clearly show the
+benefits of proposed graded-channel triple-metal double-gate structure with
+hetero-dielectric gate oxide stack. The device has reliability in low power
+applications because of its better Ion and Ioff control. Finally, the
+analytical model is validated with self-consistent numerical calculations to
+illustrate better performance of among available junctionless devices.",2109.09472v1
+2021-10-07,A ruthenium oxide thermometer for dilution refrigerators operating down to 5 mK,"At the lowest temperatures achieved in dilution refrigerators, ruthenium
+oxide resistance thermometers often saturate and therefore lose their
+sensitivity. In an effort to extend the range of such temperature sensors, we
+built a thermometer which maintains sensitivity to 5~mK. A key component of
+this thermometer is an in situ radio frequency filter which is based on a
+modern rf absorption material. We show that the use of such a filter is only
+effective when it is encased in the same rf-tight enclosure as the ruthenium
+oxide sensor. Our design delivers an attenuation level that is necessary to
+mitigate the effects of parasitic heating of a fraction of pW present in our
+circuit. Furthermore, we show that the likely origin of this parasitic heating
+is the black body radiation present within the experimental space of the
+refrigerator. We found that the equilibration time of the thermometer increases
+rapidly as the temperature is lowered; below 5~mK this thermometer becomes
+impractical because of the prohibitively long equilibration times.",2110.03788v1
+2021-10-08,Emulating homoeostatic effects with metal-oxide memristors T-dependence,"Memristor technologies have been rapidly maturing for the past decade to
+support the needs of emerging memory, artificial synapses, logic gates and
+bio-signal processing applications. So far, however, most concepts are
+developed by exploiting the tuneable resistive state of memristors with other
+physical characteristics being ignored. Here, we report on the thermal
+properties of metal-oxide memristors and demonstrate how these can be used to
+emulate a fundamental function of biological neurons: homeostasis. We show that
+thermal control mechanisms, frequently dismissed for their generally slow and
+broad-brush granularity, may in fact be an appropriate approach to emulating
+similarly slow and broad-brush biological mechanisms due to their extreme
+simplicity of implementation. We further demonstrate that metal-oxide
+memristors can be utilised as thermometers and exhibit a programmable
+temperature sensitivity. This work paves the way towards future systems that
+employ the rich physical properties of memristors, beyond their electrical
+state-tuneability, to power a new generation of advanced electronic devices.",2110.04102v1
+2021-10-11,Activity of Pd$_{\rm n}$ (n = 1-5) Clusters on Alumina Film on Ni$_3$Al(111) for CO Oxidation: A Molecular Beam Study,"Single atom catalyst (SAC) is a vivid new area of research in catalysis.
+However, the activity in CO oxidation of isolated Pt or Pd atoms, generally
+supported on an oxide powder, is still controversial. Furthermore, the steady
+state activity of few atoms clusters is still not yet quantitatively known. In
+this work we study, by molecular beam reactive scattering (MBRS), the activity
+of Pd$_{\rm n}$ ($n$ = 1-5) clusters, grown on a nanostructured alumina films
+on a Ni$_3$Al(111) surface. It is shown that the single atoms are not active at
+473 K but they diffuse and coalesce at 533K forming larger clusters. The
+activity of a cluster is proportional to the number of atoms it contains
+(n=2-5). At 533 K, the activity per (surface-) atom, which is the turnover
+frequency (TOF), is constant. Its value is close to those obtained for large
+clusters of 181$\pm$13 atoms and Pd (111) extended surfaces, in the same
+experimental conditions.",2110.05227v1
+2021-10-10,Dynamic Control of Plasmonic Colors by Voltage Actuation MEMS Cantilevers for Optical Display Applications,"Conventional optical displays using ITO (indium tin oxide) and LC (liquid
+crystal) materials present a lot of challenges in terms of long-term
+sustainability. We show here how it is possible to generate a cost effective
+and CMOS compatible fast and full range electrically controlled RGB color
+display by combining transmission based plasmonic metasurfaces with MEMS
+(Microelectromechanical systems) technology, using only two common materials:
+Aluminum and silicon oxide. White light is filtered into red, green, and blue
+components by plasmonic metasurfaces made of aluminum nanohole arrays, and the
+transmission through each color filter is modulated by MEMS miniaturized
+cantilevers fabricated with aluminum and silicon oxide on top of the color
+filters. We show that the relative transmission of a color subpixel can be
+freely modulated from 35% to 100%. Our pixels can also operate well above
+800Hz, enabling future ultrafast displays. Our work provides a road to future
+circular economic goals by exploiting advances in structural colors and MEMS
+technologies to innovate optical displays.",2110.12836v2
+2021-10-27,Emergent phenomena at oxide interfaces studied with standing-wave photoelectron spectroscopy,"Emergent phenomena at complex-oxide interfaces have become a vibrant field of
+study in the past two decades due to the rich physics and a wide range of
+possibilities for creating new states of matter and novel functionalities for
+potential devices. Electronic-structural characterization of such phenomena
+presents a unique challenge due to the lack of direct yet non-destructive
+techniques for probing buried layers and interfaces with the required
+Angstrom-level resolution, as well as element and orbital specificity. In this
+review article, we survey several recent studies wherein soft x-ray
+standing-wave photoelectron spectroscopy, a relatively newly developed
+technique, is used to investigate buried oxide interfaces exhibiting emergent
+phenomena such as metal-insulator transition, interfacial ferromagnetism, and
+two-dimensional electron gas. Advantages, challenges, and future applications
+of this methodology are also discussed.",2110.14458v1
+2021-12-15,Discovery of a reversible redox-induced order-disorder transition in a 10-cation compositionally complex ceramic,"This study discovers a reversible order-disorder transition (ODT) in a
+10-cation compositionally complex ceramic,
+(Nd0.15Pr0.15Dy0.8Ho0.8Er0.8Ti0.2Yb0.1Hf0.1Zr0.1Nb0.8)O7-delta, induced via
+annealing in oxidized vs. reduced environments at 1600C. Notably, the 10-cation
+oxide remains a homogenous single-phase high-entropy solid solution before and
+after the ODT in the pyrochlore vs. fluorite structure that can be quenched.
+In-situ neutron diffraction reveals the oxygen vacancy formation and atomic
+displacement during this ODT. The temperature dependence of thermal
+conductivity is altered by the ODT. This study reveals a new pathway to induce
+ODT via a redox transition to tailor the properties of compositionally complex
+fluorite-based oxides.",2112.07979v1
+2022-01-04,Two-dimensional superconductivity at the surfaces of KTaO3 gated with ionic liquid,"The recent observation of superconductivity at the interfaces between KTaO3
+and EuO (or LaAlO3) offers a new example of emergent phenomena at oxide
+interfaces. This superconductivity exhibits an unusual strong dependence on the
+crystalline orientation of KTaO3 and its superconducting transition temperature
+Tc is nearly one order of magnitude higher than that of the seminal
+LaAlO3/SrTiO3 interface. To understand its mechanism, it is crucial to address
+if the formation of oxide interfaces is indispensable for the presence of
+superconductivity. Here, by exploiting ionic liquid (IL) gating, we obtain
+superconductivity at KTaO3 (111) and (110) surfaces with Tc up to 2.0 K and 1.0
+K, respectively. This oxide-interface-free superconductivity gives a clear
+experimental evidence that the essential physics of KTaO3 interface
+superconductivity lies in the KTaO3 surfaces doped with electrons. Moreover,
+the ability to control superconductivity at surfaces with IL provides a simple
+way to study the intrinsic superconductivity in KTaO3.",2201.00990v1
+2022-01-13,Doping-Dependent Optical Response of a Hybrid Transparent Conductive Oxide/Plasmonic Medium,"Understanding the interaction between plasmonic nanoparticles and transparent
+conductive oxides is instrumental to the development of next-generation
+photovoltaic, opto-electronic and energy-efficient solid-state lighting
+devices. We investigated the optical response of hybrid media composed of gold
+nanoparticles deposited on aluminum-doped zinc oxide thin films with varying
+doping concentration by spectroscopic ellipsometry. The dielectric functions of
+bare AZO were addressed first, revealing doping-induced effects such as the
+band-gap shift and the appearance of free carriers. In the hybrid media, a
+blueshift of the localized surface plasmon resonance of Au NPs as a function of
+increasing Al-doping of the substrate was observed, ascribed to the occurrence
+of a charge transfer between the two materials and the doping-dependent
+variation of the polarizability of the substrate.",2201.07002v1
+2022-01-31,A Search for Alternative Solid Rocket Propellant Oxidizers,"Carbon-based caged and heterocyclic compounds tend to have strained molecular
+structures leading to high heats of formation and energetic behavior. In the
+current paper, molecular modelling calculations for 10 caged compounds of this
+type along with 2 strained aliphatic compounds and 4 simple cyclic chains are
+presented in view of their possible use as oxidizers in propulsion
+applications. Density functional theory (B3LYP) was employed for the geometry
+optimization of the proposed molecular structure using the 6-311++G(d,p) basis
+set. Heats of formation of the compounds were calculated using the molecular
+modeling results and their specific impulses were computed using the NASA CEA
+[1] software package to evaluate their potentials as propellant oxidizers.",2202.02370v1
+2022-02-03,Single nanosized graphene/TiOx multi-shells on TiO2 core via rapid-concomitant reaction pathway on metal oxide/polymer interface,"A novel design has been proposed for a facile and rapid build-up of highly
+tailorable nanostructured multishells on metal oxide particles
+(graphene/TiOx@TiO2) under a dry inert atmosphere to maximize the visible-light
+photocatalytic performance. We also thoroughly and systematically investigated
+the as-prepared nanostructured particle surface and the mechanisms of the
+extraordinary in-situ graphene growth on the TiOx@TiO2 nanoparticles achieved
+by a rapid-concomitant reaction in the metal oxide (TiO2)/polymer (polymethyl
+methacrylate) interface under microwave irradiation. The as-prepared composite
+materials are also found to perform a better photocatalytic activity in
+comparison to the traditional synthesis pathway for degradation of organic
+pollutants under visible light, associated with the synergetic effects of
+homo-/hetero-junction on TiO2.",2202.06746v1
+2022-02-05,New frontiers in characterising ZrB$_2$-MoSi$_2$ ultra-high temperature ceramics,"The structure-property(S-P) correlation,especially in the context of
+high-temperature oxidation, in ZrB$_2$-MoSi$_2$ based Ultra High-Temperature
+Ceramic Matrix Composites (UHTCMCs) have been extensively investigated for
+quite some time since the last 25 years and a countless amount of published
+data is presently available in this field.On the other hand,emergence of
+correlative microscopy [1] has completely revolutionised the world of materials
+research, in a number of ways.However,owing to the challenges of sample
+preparation, there has hardly been a literature aimed at understanding the
+aforesaid phenomenon of understanding S-P correlation,based on oxidation in
+ZrB$_2$-MoSi$_2$ UHTCMCs,which,in future, may open up new frontiers of research
+in UHTCMCs.The present review intends to discuss some of the most interesting
+data published existing in this field and intends to provide a brief overview
+of the challenges associated along with some of the currently unexplored
+avenues in this field,especially in terms of fundamental research.However,in
+view of the enormous amount of research already done in understanding
+oxidation-based S-P correlation in these materials,the author does not claim to
+address all the issues which may be associated with understanding the same.",2202.11162v1
+2022-02-23,Metalated Porous-Organic-Polymer Renders Mustard-Gas Simulant Harmless: Core Planarity Matters,"The presence of open active metal sites in Metal-Organic Frameworks (MOFs)
+exhibit higher catalytic activity. However, rational accomplishment of MOFs in
+heterogeneous catalysis is limited due to coordination bonds. Recently balanced
+characteristic feature with combination of both the covalent bonds (structural
+stability) and open metal sites (single site catalysis) introduced an entirely
+organic alternative architecture named as Metalated Porous-Organic-Polymers
+(M-POPs). In this contribution, we demonstrate successful construction of two
+Fe-POPs (Fe-Tt-POP & Fe-Rb-POP) by ternary copolymerization approach for
+catalytic oxidative decontamination of different sulfur-based mustard gas
+simulants. Fe-Tt-POP exhibited superior catalytic performance for oxidation of
+the thioanisole (TA) studied in terms of conversion (99% after 13 h) in
+comparison with Fe-Rb-POP (43% after 13h). The remarkable difference in the
+mechanistic pathways towards catalytic performance for oxidation of TA was
+investigated by in situ operando Diffuse Reflectance Infrared Fourier Transform
+Spectroscopy (DRIFTS) analysis, complemented by Density Functional Theory (DFT)
+computational study.",2202.11677v1
+2022-02-26,Predicting the formation and stability of oxide perovskites by extracting underlying mechanisms using machine learning,"The optimization of properties of perovskite oxides has drawn interest on
+account of their diverse areas of application. In this work, the hierarchical
+clustering technique is used to reduce the multi-collinearity among selected
+features from literature that are reported to have an effect on perovskite
+formation and stability. Operating on the vast composition space of double
+oxide perovskite compositions available in literature and online repositories,
+in this manuscript, an attempt has been made to extract the relationship
+between the composition and structure to predict their formability and
+stability. Machine learning (ML) classifiers are trained on these datasets to
+predict novel stable perovskite compositions. The study uses a vast feature
+space to narrow down the most important factors affecting the formability and
+stability in perovskite compounds. It also identifies stable compositions that
+have band gaps suitable for photovoltaic and photocatalytic applications. The
+developed random forest (RF)-based models may be extended to include the
+implications beyond photosensitive applications by focusing on the
+physico-chemical mechanisms driving the phenomena behind each application.",2202.13087v1
+2022-02-28,Hybrid Molecular Beam Epitaxy of Ge-based Oxides,"Germanium-based oxides such as rutile GeO2 are garnering attention owing to
+their wide band gaps and the prospects for ambipolar doping for application in
+high-power devices. Here, we present the use of germanium tetraisopropoxide
+(GTIP) (an organometallic chemical precursor) as a source of Ge for the
+demonstration of hybrid molecular beam epitaxy (MBE) for Ge-containing
+compounds. We use Sn1-xGexO2 and SrSn1-xGexO3 as model systems to demonstrate
+this new synthesis method. A combination of high-resolution X-ray diffraction,
+scanning transmission electron microscopy, and X-ray photoelectron spectroscopy
+confirms the successful growth of epitaxial rutile Sn1-xGexO2 on TiO2(001)
+substrates up to x = 0.54 and coherent perovskite SrSn1-xGexO3 on GdScO3(110)
+substrates up to x = 0.16. Characterization and first-principles calculations
+corroborate that Ge preferentially occupies the Sn site, as opposed to the Sr
+site. These findings confirm the viability of the GTIP precursor for the growth
+of germanium-containing oxides by hybrid MBE, and thus open the door to
+high-quality perovskite germanate films.",2202.13494v1
+2022-03-06,Scaled indium oxide transistors fabricated using atomic layer deposition,"In order to continue to improve integrated circuit performance and
+functionality, scaled transistors with short channel lengths and low thickness
+are needed. But the further scaling of silicon-based devices and the
+development of alternative semiconductor channel materials that are compatible
+with current fabrication processes is challenging. Here we report
+atomic-layer-deposited indium oxide transistors with channel lengths down to 8
+nm, channel thicknesses down to 0.5 nm and equivalent dielectric oxide
+thickness down to 0.84 nm. Due to the scaled device dimensions and low contact
+resistance, the devices exhibit high on-state currents of 3.1 A/mm at a drain
+voltage of 0.5 V and a transconductance of 1.5 S/mm at a drain voltage 1 V. Our
+devices are a promising alternative channel material for scaled transistors
+with back-end-of-line processing compatibility.",2203.02869v1
+2022-03-09,Modelling dielectric loss in superconducting resonators: Evidence for interacting atomic two-level systems at the Nb/oxide interface,"While several experiments claim that two-level system (TLS) defects in
+amorphous surfaces/interfaces are responsible for energy relaxation in
+superconducting resonators and qubits, none can provide quantitative
+explanation of their data in terms of the conventional noninteracting TLS
+model. Here a model that interpolates between the interacting and
+noninteracting TLS loss tangent is proposed to perform numerical analysis of
+experimental data and extract information about TLS parameters and their
+distribution. As a proof of principle, the model is applied to TESLA cavities
+that contain only a single lossy material in their interior, the
+niobium/niobium oxide interface. The best fits show interacting TLSs with a
+sharp modulus of electric dipole moment for both thin (5 nm) and thick (100 nm)
+oxides, indicating that the TLSs are ""atomic"" instead of ""glassy"". The proposed
+method can be applied to other devices with multiple material interfaces and
+substrates, with the goal of elucidating the nature of TLSs causing energy loss
+in resonators and qubits.",2203.05054v3
+2022-03-14,In situ study of zinc peroxide decomposition to zinc oxide by X-ray absorption spectroscopy and reverse Monte-Carlo simulations,"The Zn K-edge X-ray absorption spectroscopy has been used to investigate in
+situ the decomposition of zinc peroxide (ZnO$_2$) to zinc oxide (ZnO).
+Principal component and linear combination analyses of the EXAFS spectra have
+been employed to identify the phase composition of the oxide upon heating to
+900$^\circ$C. Only the ZnO$_2$ phase has been found up to 180$^\circ$C, whereas
+only the nanocrystalline ZnO phase has occurred above 250$^\circ$C. Detailed
+structural information on the temperature dependence of the local environment
+of zinc atoms has been obtained using the reverse Monte Carlo simulations. A
+strong increase of disorder has been found upon approaching the decomposition
+temperature, evidenced by the broadening of Zn-O and Zn-Zn pair distribution
+functions and related mean-square relative displacements.",2203.07170v2
+2022-03-14,Water Oxidation and Hydrogen Evolution with Organic Photooxidants: A Theoretical Perspective,"In this perspective, we discuss a novel water-splitting scenario, namely the
+direct oxidation of water molecules by organic photooxidants in hydrogen-bonded
+chromophore-water complexes. In comparison with the established scenario of
+semiconductor-based water splitting, the distance of electron transfer
+processes is thereby reduced from mesoscopic scales to the {\AA}ngstr{\o}m
+scale and the time scale is reduced from milliseconds to femtoseconds, which
+suppresses competing loss processes. The concept is illustrated by
+computational studies for the heptazine-H2O complex. The excited-state
+landscape of this complex has been characterized with ab initio
+electronic-structure methods and the proton-coupled electron-transfer dynamics
+has been explored with nonadiabatic dynamics simulations. A unique feature of
+the heptazine chromophore is the existence of a low-lying and exceptionally
+long-lived 1{\pi}{\pi}* state in which a substantial part of the photon energy
+can be stored for hundreds of nanoseconds and is available for the oxidation of
+water molecules. The calculations reveal that the absorption spectra and the
+photochemical functionalities of heptazine chromophores can be systematically
+tailored by chemical substitution. The options of harvesting hydrogen and the
+problems posed by the high reactivity of OH radicals are discussed.",2203.07176v1
+2022-03-18,Implications of phonon anisotropy on thermal conductivity of fluorite oxides,"Fluorite oxides are attractive ionic compounds for a range of applications
+with critical thermal management requirements. In view of recent reports
+alluding to anisotropic thermal conductivity in this face-centered cubic
+crystalline systems, we perform a detailed analysis of the impact of
+direction-dependent phonon group velocities and lifetimes on the thermal
+transport of fluorite oxides. We demonstrate that the bulk thermal conductivity
+of this class of materials remains isotropic despite notable anisotropy in
+phonon lifetime and group velocity. However, breaking the symmetry of the
+phonon lifetime under external stimuli including boundary scattering present in
+nonequilibrium molecular dynamics simulations of finite size simulation cell
+gives rise to apparent thermal conductivity anisotropy. We observe that for
+accurate determination of thermal conductivity, it is important to consider
+phonon properties not only along high symmetry directions commonly measured in
+inelastic neutron or x-ray scattering experiments but also of those along lower
+symmetry. Our results suggests that certain low symmetry directions have a
+larger contribution to thermal conductivity compared to high symmetry ones.",2203.09923v2
+2022-04-11,Nonlinear optical response of ferroelectric oxides: first-principles calculations within the time-domain and the frequency-domain,"The second and third order nonlinear susceptibilities of the ferroelectric
+oxides LiNbO$_3$, LiTaO$_3$, and KNbO$_3$ are calculated from first principles.
+Two distinct methodologies are compared, one approach is based on a
+perturbative approach within the frequency-domain, another on the
+time-evolution of the electric polarization. The frequency dependence of the
+second harmonic coefficients of the ferroelectric phase of LiNbO$_3$ calculated
+within the two approaches is in excellent agreement. This is further validated
+by experimental data for LiNbO$_3$ and LiTaO$_3$, measured for an incident
+range of photon energies between 0.78 eV and 1.6 eV. The real-time based
+approach is furthermore employed to estimate the third order nonlinear
+susceptibilities of all investigated ferroelectric oxides. We further show that
+the quasiparticle effects, considered by means of a scissors-shift in
+combination with the the computationally efficient independent particle
+approximation, result in a shift all spectral features towards higher energies
+and decrease the magnitude of the optical nonlinearities. The energy of the
+main resonances in the hyperpolarizabilities suggests that the spectra can be
+understood by multi-photon adsorption within the fundamental bandgap for all
+investigated materials.",2204.04985v1
+2022-05-10,Effect of substrate temperature on the optoelectronic properties of DC magnetron sputtered copper oxide films,"Copper oxide thin films are deposited on quartz substrates by DC magnetron
+sputtering and the effect of deposition temperature on their optoelectronic
+properties is examined in detail. Scanning Electron Microscopy (SEM), X-ray
+diffraction (XRD) analysis, Raman spectroscopy, UV-Vis spectroscopy, and
+four-probe sheet resistance measurements are used to characterize the surface
+morphology, structural, optical, and electrical properties respectively.
+Deposition is carried out at room temperature and between 200 and 300 {\deg}C.
+XRD analysis indicates that the oxide formed is primarily Cu$_2$O and the
+absorption spectra show the films have a critical absorption edge at around 300
+nm. The sheet resistance gradually decreases with increase in deposition
+temperature thereby increasing the conductivity of these thin films. Also
+observed is the increase in band gap from 2.20 eV for room temperature
+deposition to 2.35 eV at 300 {\deg}C. The optical band gap and the variation of
+sheet resistance with temperature shows that the microstructure plays a vital
+role in their behavior. These transformation characteristics are of huge
+technological importance having variety of applications including transparent
+solar cell fabrication.",2205.05615v1
+2022-05-19,Ultrafast structural color change in indium tin oxide/titanium dioxide 1D photonic crystal,"Photonic crystals can integrate plasmonic materials such as indium tin oxide
+(ITO) in their structure. Exploiting ITO plasmonic properties it is possible to
+tune the photonic band gap of the photonic crystal upon the application of an
+external stimuli. In this work, we have fabricated a one-dimensional multilayer
+photonic crystal via radiofrequency sputtering and we have triggered its
+optical response with ultrafast pump-probe spectroscopy. Upon photoexcitation
+we observe a change in the refractive index of indium tin oxide. Such effect
+has been used to create a photonic crystal that change its photonic bandgap in
+an ultrafast time scale. All optical modulation in the visible region, that can
+be tuned by designing the photonic crystal, has been demonstrated.",2205.09694v1
+2022-06-09,Perspective: Molecular beam epitaxy of antiperovskite oxides,"Antiperovskites, or inverse perovskites, have recently emerged as a material
+class with a plethora of promising electronic properties. This perspective
+describes the molecular beam epitaxy (MBE) growth of oxide antiperovskites
+Sr$_3$PbO and Sr$_3$SnO. We show that MBE offers great potential not only in
+growing antiperovskites with high structural quality, but also in providing a
+means to seamlessly connect with advanced characterization tools, including
+x-ray photoelectron spectroscopy (XPS), low-energy electron diffraction (LEED),
+reflection high-energy electron diffraction (RHEED), and scanning tunneling
+microscopy (STM), to facilitate the analyses of their intrinsic properties. The
+initial results point toward the feasibility of atomically controlled
+antiperovskite growth, which could open doors to study topological and
+correlated electronic states in an electronic environment quite distinct from
+what is available in conventional complex oxides.",2206.04768v1
+2022-07-07,Oxygen vacancy dynamics in Pt/TiOx/TaOy/Pt memristors: exchange with the environment and internal electromigration,"Memristors are expected to be one of the key building blocks for the
+development of new bio-inspired nanoelectronics. Memristive effects in
+transition metal oxides are usually linked to the electromigration at the
+nanoscale of charged oxygen vacancies (OV). In this paper we address, for
+Pt/TiOx/TaOy/Pt devices, the exchange of OV between the device and the
+environment upon the application of electrical stress. From a combination of
+experiments and theoretical simulations we determine that both TiOx and TaOy
+layers oxidize, via environmental oxygen uptake, during the electroforming
+process. Once the memristive effect is stabilized (post-forming behavior) our
+results suggest that oxygen exchange with the environment is suppressed and the
+OV dynamics that drives the memristive behavior is restricted to an internal
+electromigration between TiOx and TaOy layers. Our work provides relevant
+information for the design of reliable binary oxide memristive devices.",2207.03538v1
+2022-07-12,Digital Twins solve the mystery of Raman spectra of parental and reduced graphene oxides,"A still amazing identity of the D-G doublet Raman spectra of parental and
+reduced graphene oxides is considered from the digital twins viewpoint. About
+thirty DTs, presenting different aspects of the GO structure and properties,
+were virtually synthesized using atomic spin-density algorithm, which allowed
+reliably displaying reasons for this extraordinary spectral feature. In both
+cases, it was established that the D-G doublets owe their origin to the sp3-sp2
+C-C stretchings, respectively. This outwardly similar community of the doublets
+origin of GO and rGO is thoroughly analyzed to reveal different grounds of the
+feature in the two cases. Multilayer packing of individual rGO molecules in
+stacks, in the first case, and spin-influenced prohibition of the 100%
+oxidative reaction, the termination of which is accompanied with a particular
+set of highly ordered by length sp3- and sp2 C-C bonds, protecting the carbon
+carcass from destruction caused by the stress induced sp2-to-sp3
+transformation, in the second, are the main reasons. The DT concept has been
+realized on the basis of virtual vibrational spectrometer HF Spectrodyn.",2207.05744v1
+2022-07-28,Electronic interaction $U_{pp}$ on oxygen $p$ orbitals in oxides: Role of correlated orbitals on the example of UO$_2$ and TiO$_2$,"We carry out a detailed study of the role of electronic interaction on $p$
+oxygen orbitals in a Mott insulator oxide (UO$_2$) and a charge transfer oxide
+(TiO$_2$). First, we calculate values of effective interactions \Uff, \Upp{}
+and $U_{fp}$ in UO$_2$ and \Udd{}, \Upp{} and $U_{dp}$ in TiO$_2$. Second, we
+analyze the role of electronic interactions \Upp{} on $p$ orbitals of oxygen in
+spectral and structural properties. Finally, we show that this role depends
+strongly on the definition of correlated orbitals and that using Wannier
+functions leads to more physical results for spectral and structural
+properties.",2207.14137v2
+2022-08-11,Superconductivity in epitaxially grown LaVO3/KTaO3(111) heterostructures,"Complex oxide heterointerfaces can host a rich of emergent phenomena, and
+epitaxial growth is usually at the heart of forming these interfaces. Recently,
+a strong crystalline-orientation-dependent two-dimensional superconductivity
+was discovered at interfaces between KTaO3 single-crystal substrates and films
+of other oxides. Unexpectedly, rare of these oxide films was epitaxially grown.
+Here, we report the existence of superconductivity in epitaxially grown
+LaVO3/KTaO3(111) heterostructures, with a superconducting transition
+temperature of ~0.5 K. Meanwhile, no superconductivity was detected in the
+(001)- and (110)-orientated LaVO3/KTaO3 heterostructures down to 50 mK.
+Moreover, we find that for the LaVO3/KTaO3(111) interfaces to be conducting, an
+oxygen-deficient growth environment and a minimum LaVO3 thickness of ~0.8 nm (~
+2 unit cells) are needed.",2208.05712v3
+2022-08-16,Strain effect on the ground-state structure of Sr2SnO4 Ruddlesden-Popper oxides,"Ruddlesden-Popper (RP) oxides (A$_{n+1}$B$_n$O$_{3n+1}$) comprised of
+perovskite (ABO$_3$)$_n$ slabs can host a wider variety of structural
+distortions than their perovskite counterparts. This makes accurate structural
+determination of RP oxides more challenging. In this study, we investigate the
+structural phase diagram of $n=1$ RP Sr$_2$SnO$_4$, one of alkaline earth
+stannates that are promising for opto-electronic applications by using group
+theory-based symmetry analysis and first-principles calculations. We explore
+the symmetry breaking effects of different dynamical instabilities, predict the
+energies of phases they lead to, and take into account different (biaxial
+strain and hydrostatic pressure) boundary conditions. We also address the
+effect of structural changes on the electronic structure and find that
+compressive biaxial strain drives Sr$_2$SnO$_4$ into a regime with wider
+bandgap and lower electron effective mass.",2208.07481v2
+2022-08-30,Optimizing nucleation layers for the integration of ferroelectric HZO on CVD-grown graphene,"Direct integration of ferroelectric Hf0.5Zr0.5O2 (HZO) on the inert surface
+of graphene is challenging. Here, using nucleation layers to promote atomic
+layer deposition of HZO was investigated. Different metals were deposited as
+nucleation layers via dc sputtering. Ta, which oxidizes in air to form a
+sub-stoichiometric oxide, was compared to Pt, which offers a more stable
+electrode. For thicker interlayers, Ta leads to unstable switching behavior of
+the HZO film. Conversely, at smaller thicknesses, a higher Pr can be achieved
+with an oxidized Ta interlayer. In both cases, Pt offers higher endurance. The
+choice of interlayer may strongly depend on the required application.",2208.14061v2
+2022-09-09,CO oxidation by Pt2/Fe3O4: metastable dimer and support configurations facilitate lattice oxygen extraction,"Heterogeneous catalysts based on sub-nanometer metal clusters often exhibit
+strongly size-dependent properties, and the addition or removal of a single
+atom can make all the difference. Identifying the most active species and
+deciphering the reaction mechanism is extremely difficult, however, because it
+is often not clear how the catalyst evolves in operando. Here, we utilize a
+combination of atomically resolved scanning probe microscopies, spectroscopic
+techniques, and density functional theory (DFT)-based calculations to study CO
+oxidation by a model Pt/Fe3O4(001) single-atom catalyst. We demonstrate that
+(PtCO)2 dimers, formed dynamically through the agglomeration of mobile
+Pt-carbonyl species, catalyse a reaction involving the oxide support to form
+CO2. Pt2 dimers produce one CO2 molecule before falling apart into two adatoms,
+releasing the second CO. Interestingly, Olattice extraction only becomes facile
+when both the Pt-dimer and the Fe3O4 support can access metastable
+configurations, suggesting that substantial, concerted rearrangements of both
+cluster and support must be considered for reactions occurring at elevated
+temperature.",2209.04222v1
+2022-09-06,Study of uranium oxide milling in order to obtain nanostructured UCx target,"A R&D program is developed at the ALTO facility to provide new beams of
+exotic neutron-rich nuclei, as intense as possible. In the framework of
+European projects, it has been shown that the use of refractory targets with
+nanometric structure allows us to obtain beams of nuclei unreachable until now.
+The first parameter to be controlled in the processing to obtain targets with a
+homogeneous nanostructure is the grinding of uranium dioxide, down to 100 nm
+grain size. In this study, dry and wet grinding routes are studied and the
+powders are analyzed in terms of phase stabilization, specific surface area and
+grain morphology. It appears that the grinding, as well dry as wet, leads to
+the decrease of the particle size. The oxidation of UO2 is observed whatever
+the grinding. However, the dry grinding is the most efficient and leads to the
+oxidation of UO2 into U4O9 and U3O7 whose quantities increase with the grinding
+time while crystallite sizes decrease.",2209.05230v1
+2022-09-13,Ab Initio Calculations of XUV Ground and Excited States for First-Row Transition Metal Oxides,"Transient X-ray spectroscopies have become ubiquitous in studying
+photoexcited dynamics in solar energy materials due to their sensitivity to
+carrier occupations and local chemical or structural dynamics. The
+interpretation of solid-state photoexcited dynamics, however, is complicated by
+the core-hole perturbation and the resulting many-body dynamics. Here, an ab
+initio, Bethe-Salpeter equation (BSE) approach is developed that can
+incorporate photoexcited state effects for solid-state materials. The extreme
+ultraviolet (XUV) absorption spectra for the ground, photoexcited, and
+thermally expanded states of first row transition metal oxides - $TiO_2,
+\alpha-Cr_2O_3, \beta-MnO_2, \alpha-Fe_2O_3, Co_3O_4, NiO, CuO, and ZnO$ - are
+calculated to demonstrate the accuracy of this approach. The theory is used to
+decompose the core-valence excitons into the separate components of the X-ray
+transition Hamiltonian for each of the transition metal oxides investigated.
+The decomposition provides a physical intuition about the origins of XUV
+spectral features as well as how the spectra will change following
+photoexcitation. The method is easily generalized to other K, L, M, and N edges
+to provide a general approach for analyzing transient X-ray absorption or
+reflection data.",2209.06347v1
+2022-09-16,Rashba-like spin-orbit interaction and spin texture at the KTaO$_\text{3}$ (001) surface from DFT calculations,"Rashba-like spin-orbit interaction at oxide heterostructures emerges as a
+much sought-after feature in the context of oxide spintronics and
+spin-orbitronics. KTaO$_3$ (KTO) is one of the best substrates available for
+the purpose, owing to its strong spin-orbit interaction and alternating $+1|-1$
+charged layers along the (001) direction. Employing first-principles
+calculations within density functional theory (DFT) and proposing a possible
+electrostatic model for charge transfer to the surfaces of KTO slabs, we
+comprehensively analyze Rashba-like spin-orbit interaction with the help of
+three-dimensional band dispersion, isoenergetic contours, and projected spin
+textures $-$ all directly obtained from our DFT results $-$ in a thin
+insulating slab and a conducting thick slab of KTO. Our results reveal
+reasonably strong linear Rashba interaction with no signature of Dresselhaus or
+higher order Rashba interactions in the systems considered here. The rigorous
+analysis presented here may be crucial for future developments in oxide
+spintronics.",2209.07723v1
+2022-10-27,Zeolite-based photocatalysts immobilized on aluminum support by plasma electrolytic oxidation,"The preparation and properties of zeolite-containing oxide coatings obtained
+by plasma electrolytic oxidation are investigated and discussed. Pure and
+Ce-exchanged natural (clinoptilolite) and synthetic (13X) zeolites are
+immobilized on aluminum support from silicate-based electrolyte. Obtained
+coatings are characterized with respect to their morphology, phase and chemical
+composition, photocatalytic activity and anti-corrosion properties. It is
+observed that all mentioned properties of obtained coatings are dependent on
+processing time and type of immobilized zeolite. Coatings with Ce-exchanged
+zeolite show higher photocatalytic activity and more effective corrosion
+protection than those with pure zeolite. The highest photocatalytic activity is
+observed for coatings processed in pulsed a DC regime for 30 minutes containing
+Ce-exchanged 13X zeolite, followed by those containing Ce-exchanged
+clinoptilolite. Pronounced anti-corrosion properties feature almost all samples
+containing Ce-exchanged 13X zeolite.",2210.15455v1
+2022-11-01,Programmable Charge Trap for Junction-less selective extraction of holes in Solar Cells,"Selective extraction of photo-generated carriers is a fundamental challenge
+in solar cells which is usually achieved through junctions with the associated
+doping as well as band offset differences. In this context, here we propose a
+new paradigm for selective extraction for majority carriers through novel usage
+of the programmable charge trap which comprises of Oxide-Nitride-Oxide (ONO)
+stack and has the primary function of holding electrically injected charge.
+Through detailed numerical simulations, here we show that such a charge trap
+with an additional metal contact can (i) compensate for efficiency loss due to
+sub-optimal passivation and sub-optimal hole selectivity in homojunction as
+well as transition metal oxide-based heterojunction solar cells and (ii) can
+also function as a standalone hole selection scheme. The proposed scheme, with
+its easy integration and the capability of programmable compensation of
+performance loss, is of interest to the photovoltaic community.",2211.00540v1
+2022-11-04,"Ferroelectric Switching Pathways and Domain Structure of SrBi$_2$(Ta,Nb)$_2$O$_9$ from First Principles","Several families of layered perovskite oxide ferroelectrics exhibit a
+coupling between polarization and structural order parameters, such as
+octahedral rotation distortions. This coupling provides opportunities for novel
+electric field-based manipulation of material properties, and also stabilizes
+complex domain patterns and domain wall vortices. Amongst layered perovskites
+with such coupled orders, the Aurivillius-phase oxides SrBi$_2B_2$O$_9$
+($B$=Ta, Nb) are well-known for their excellent room temperature ferroelectric
+performance. This work combines group theoretic analysis with density
+functional theory calculations to examine the ferroelectric switching processes
+of SrBi$_2B_2$O$_9$. Low-energy two-step ferroelectric switching paths are
+identified, with polarization reversal facilitated by structural order
+parameter rotations. Analysis of the domain structure reveals how the relative
+energetics of the coupled order parameters translates into a network of several
+distinct domain wall types linked by domain wall vortex structures. Comparisons
+are made between the ferroelectric switching and domain structure of
+SrBi$_2B_2$O$_9$ and those of the layered $n$=2 Ruddlesden-Popper hybrid
+improper ferroelectrics. The results provide new insight into how ferroelectric
+properties may be optimized by engineering the complex crystal structures of
+Aurivllius-phase oxides.",2211.02735v1
+2022-11-12,Contact Angle Studies on Porous Silicon: Evidence for Heterogeneous Wetting and Implications of Oxidation,"A study of wetting was carried out on porous silicon films with pore
+diameters spanning three orders of magnitude. Water contact angle measurements
+on adjoining porous and nonporous regions yielded Wenzel roughness ratios that
+were either unphysical (less than unity) or unrealistically low when compared
+to those expected from specific surface area considerations. Moreover, results
+obtained from a sample consisting of a microporous film on a macroporous layer
+gave contact angles that were very similar to those found on films consisting
+of only a single microporous layer, contrary to what would be expected for
+complete filling of the pores by liquid. Values for wetted surface fractions
+calculated from the Cassie-Baxter model are unreasonably high for micro- ,
+meso- and oxidized macroporous films considering their porosities, while
+relatively oxide-free macroporous films give wetted surface fractions in accord
+with those expected based on film porosity. Collectively, these results show
+that the predominant mode of wetting on these films is heterogeneous.",2211.06554v1
+2022-11-15,Intergranular corrosion in evolving media: experiment and modeling by cellular automata,"We investigate the impact of the oxidizing character of the nitric medium on
+the evolution of the intergranular corrosion of a stainless steel. In two
+different oxidizing conditions (""severe"" and ""soft""), the corroded surface of
+the steel reaches a different steady state: the oxide is thicker, the
+intergranular grooves are thinner and the surface area is larger in the
+""severe"" conditions than in the ""soft"" ones. Then we investigate the effect of
+an alternative ""severe then soft"" corrosion sequence. We show that the system
+re-adapts to the ""soft"" conditions without memory effect from the previous
+""severe"" ones. bstra",2211.08276v1
+2022-12-05,A study of PbF2 nanoparticles crystallization mechanism in mixed oxyde-fluoride glasses,"The heat-treated oxyfluoride glasses with different contents of thulium Tm3+
+and holmium Ho3+ ions have been studied using small-angle X-ray scattering and
+diffraction. With an increase in relative concentration of added Ho2O3 and
+Tm2O3 oxides, the growing in the average size of both nanoparticles and local
+density fluctuations in the glass matrix is observed. In addition, at high
+relative concentrations of initial rare-earth oxides, the appearance of a
+crystalline cubic phase PbF2:Tm-Ho is observed, which can provide a source of
+up-conversion luminescence in the studied glass materials. A change in the
+concentration of the initial Ho2O3 and Tm2O3 oxides does not effect on a
+morphology and fractal dimension of the formed luminescence nanoparticles. The
+structural aspects of nanoparticle formation with up-conversion luminescence
+phenomenon are discussed.",2212.02189v1
+2022-12-15,Quantitative 3D mapping of chemical defects at charged grain boundaries in a ferroelectric oxide,"Polar discontinuities and structural changes at oxide interfaces can give
+rise to a large variety of electronic and ionic phenomena. Related effects have
+been intensively studied in epitaxial systems, including ferroelectric domain
+walls and interfaces in superlattices. Here, we investigate the relation
+between polar discontinuities and the local chemistry at grain boundaries in
+polycrystalline ferroelectric ErMnO3. Using orientation mapping and different
+scanning probe microscopy techniques, we demonstrate that the polycrystalline
+material develops charged grain boundaries with enhanced electronic
+conductance. By performing atom probe tomography measurements, we find an
+enrichment of erbium and a depletion of oxygen at all grain boundaries. The
+observed compositional changes translate into a charge that exceeds possible
+polarization-driven effects, demonstrating that structural phenomena rather
+than electrostatics determine the local chemical composition and related
+changes in the electronic transport behavior. The study shows that the charged
+grain boundaries behave distinctly different from charged domain walls, giving
+additional opportunities for property engineering at polar oxide interfaces.",2212.07924v2
+2023-01-07,Defective high-entropy oxide photocatalyst with high activity for CO2 conversion,"High-entropy oxides (HEOs), as a new family of materials with five or more
+principal cations, have shown promising properties for various applications. In
+this work and inspired by inherent defective and strained structure of HEOs,
+photocatalytic CO2 conversion is examined on a dual-phase TiZrNbHfTaO11
+synthesized by a two-step high-pressure torsion mechanical alloying and
+high-temperature oxidation. The HEO, which had various structural defects,
+showed simultaneous photocatalytic activity for CO2 to CO and H2O to H2
+conversion without the addition of a co-catalyst. The photocatalytic activity
+of this HEO for CO2 conversion was better than conventional photocatalysts such
+as anatase TiO2 and BiVO4 and similar to P25 TiO2. The high activity of HEO was
+discussed in terms of lattice defects, lattice strain, light absorbance, band
+structure, photocurrent generation and charge carrier mobility to activation
+centers. The current study confirms the high potential of HEOs as a new family
+of photocatalysts for CO2 conversion.",2301.05008v1
+2023-02-06,B dopant evolution in Pd catalysts after H evolution/oxidation reaction in alkaline environment,"Introduction of interstitial dopants has opened a new pathway to optimize
+nanoparticle catalytic activity for, e.g., hydrogen evolution/oxidation and
+other reactions. Here, we discuss the stability of a property-enhancing dopant,
+B, introduced through controlled synthesis of an electrocatalyst Pd aerogel. We
+observe significant removal of B after the hydrogen evolution/oxidation
+reaction. Ab-initio calculations show that the high stability of sub-surface B
+in Pd is substantially reduced when H is ad/absorbed on the surface, favoring
+its departure from the host nanostructure. The destabilization of sub-surface B
+is more pronounced as more H occupies surface sites and empty interstitial
+sites. We hence demonstrate that the H2 fuel/product itself favors the
+microstructural degradation of the electrocatalyst and an associated drop in
+activity.",2302.02588v1
+2023-02-24,Operando analysis of a solid oxide fuel cell by environmental transmission electron microscopy,"Correlating the microstructure of an energy conversion device to its
+performance is often a complex exercise, notably in solid oxide fuel cell
+(SOFC) research. SOFCs combine multiple materials and interfaces that evolve in
+time due to high operating temperatures and reactive atmospheres. We
+demonstrate here that operando environmental transmission electron microscopy
+can simplify the identification of structure-property links in such systems. By
+contacting a cathode-electrolyte-anode cell to a heating and biasing
+microelectromechanical system in a single-chamber configuration, a direct
+correlation is found between the environmental conditions (O2 and H2 partial
+pressures, temperature), the cell voltage, and the microstructural evolution of
+the fuel cell, down to the atomic scale. The results shed new insights into the
+impact of the anode oxidation state and its morphology on the cell electrical
+properties.",2302.12514v1
+2023-03-09,Graphene on quartz modified with rhenium oxide as a semitransparent electrode for organic electronic,"Our research shows that commercially available graphene on quartz modified
+with rhenium oxide meets the requirements for its use as a conductive and
+transparent anode in optoelectronic devices. The cluster growth of rhenium
+oxide enables an increase in the work function of graphene by 1.3 eV up to 5.2
+eV, which guarantees an appropriate adjustment to the energy levels of the
+organic semiconductors used in OLED devices.",2303.05303v2
+2023-03-21,Numerical simulation of self-oscillating catalytic reaction in a plug-flow reactor,"Self-oscillations in some oxidation reactions on metal catalysts are
+associated with periodic oxidation/reduction of the catalyst surface. If the
+reaction proceeds in a flow reactor at atmospheric pressure, then the reaction
+dynamics is complicated by the mass transfer in the gas phase. In this paper,
+the reaction in a flow reactor is described by an 1D system of
+advection-diffusion-reaction equations with an abstract STM-type kinetic model
+of the surface catalytic reaction. The dependencies of the solution of the
+system on the reaction parameters, the intensity of diffusion in the adsorption
+layer, and on the gas flow rate are studied numerically. Solutions such as
+localized oscillations (""breathing"" structures) and mobile oxidation/reduction
+fronts on the catalyst surface are constructed.",2303.12022v1
+2023-03-25,Surface termination control of charge transfer and band alignment across a semiconductor-crystalline oxide heterojunction,"Charge redistribution across heterojunctions has long been utilized to induce
+functional response in materials systems. Here we examine how the composition
+of the terminating surface affects charge transfer across a heterojunction
+consisting of Si and the crystalline complex oxide SrTiO3. Itinerant electrons
+in Si migrate across the interface toward the surface of SrTiO3 due to surface
+depletion. The electron transfer in turn creates an electric field across the
+interface that modifies the interfacial dipole associated with bonding between
+SrTiO3 and Si, leading to a change in the band alignment from type-II to
+type-III. By capping the SrTiO3 surface with ultra-thin layers of BaO, SrO or
+TiO2, charge transfer across the interface can be weakened or inhibited. Ab
+initio modeling implicates the adsorption of oxygen as driving surface
+depletion in SrTiO3. The electronic coupling between the surface and buried
+interface expands the functionality of semiconductor-crystalline oxide
+heterojunctions.",2303.14323v1
+2023-04-11,Accessible Chemical Space for Metal Nitride Perovskites,"Building on the extensive exploration of metal oxide and metal halide
+perovskites, metal nitride perovskites represent a largely unexplored class of
+materials. We report a multi-tier computational screening of this chemical
+space. From a pool of 3660 ABN$_3$ compositions covering I-VIII, II-VII, III-VI
+and IV-V oxidation state combinations, 279 are predicted to be chemically
+feasible. The ground-state structures of the 25 most promising candidate
+compositions were explored through enumeration over octahedral tilt systems and
+global optimisation. We predict 12 dynamically and thermodynamically stable
+nitride perovskite materials, including YMoN$_3$, YWN$_3$, ZrTaN$_3$, and
+LaMoN$_3$. These feature significant electric polarisation and low predicted
+switching electric field, showing similarities with metal oxide perovskites and
+making them attractive for ferroelectric memory devices",2304.05450v1
+2023-05-07,Phase stability of entropy stabilized oxides with the $α$-PbO$_2$ structure,"The prediction of new high entropy oxides (HEOs) remains a profound challenge
+due to their inherent chemical complexity. In this work, we combine
+experimental and computational methods to search for new HEOs in the
+tetravalent $A$O$_2$ family, using exclusively $d^0$ and $d^{10}$ cations, and
+to explain the observed phase stability of the $\alpha$-PbO$_2$ structure, as
+found for the medium entropy oxide (Ti, Zr, Hf, Sn)O$_2$. Using a pairwise
+approach to approximate the mixing enthalpy, we confirm that $\alpha$-PbO$_2$
+is the expected lowest energy structure for this material above other
+candidates including rutile, baddeleyite, and fluorite structures. We also show
+that no other five-component compound composed of the tetravalent cations
+considered here is expected to form under solid state synthesis conditions,
+which we verify experimentally. Ultimately, we conclude that the flexible
+geometry of the $\alpha$-PbO$_2$ structure can be used to understand its
+stability among tetravalent HEOs.",2305.04221v1
+2023-05-09,Photo-Induced CO Desorption Dominates over Oxidation on Different O+CO Covered Ru(0001) Surfaces,"The photo-induced desorption and oxidation of CO on Ru(0001) is simulated
+using ab initio molecular dynamics with electronic friction that accounts for
+the non-equilibrated excited electrons and phonons. Different (O,CO) coverages
+are considered, the experimental room temperature coverage consisting in
+0.5ML-O+0.25ML- CO (low coverage), the saturation coverage achieved
+experimentally at low temperatures (0.5ML-O+0.375ML-CO, intermediate coverage),
+and the equally mixed monolayer that is stable according to our calculations
+but not experimentally observed yet (0.5ML-O+0.5ML-CO, high coverage). The
+results of our simulations for the three coverages are consistent with
+femtosecond laser experiments showing that the CO photo-desorption largely
+dominates over CO photo-oxidation. These results cannot be explained in terms
+of the distinct activation energies calculated for the relaxed surfaces.
+Different (dynamical) factors such as the coupling to the laser-excited
+electrons and, more importantly, the interadsorbate energy exchange and the
+strong surface distortions induced in the more crowded surfaces are fundamental
+to understand the competition between these two processes under the extremely
+non-equilibrated conditions created by the laser.",2305.05298v2
+2023-05-11,Thermodynamic properties for metal oxides from first-principles,"In this study, an efficient first-principles approach for calculating the
+thermodynamic properties of mixed metal oxides at high temperatures is
+demonstrated. More precisely, this procedure combines density functional theory
+and harmonic phonon calculations with tabulated thermochemical data to predict
+the heat capacity, formation energy, and entropy of important metal oxides.
+Alloy cluster expansions are, moreover, employed to represent phases that
+display chemical ordering as well as to calculate the configurational
+contribution to the specific heat capacity. The methodology can, therefore, be
+applied to compounds with vacancies and variable site occupancies. Results are,
+moreover, presented for a number of systems of high practical relevance:
+Fe-K-Ti-O, K-Mn-O, and Ca-Mn-O. In the case of ilmenite (FeTiO3), the agreement
+with experimental measurements is exceptionally good. When the generated data
+is used in multi-phase thermodynamic calculations to represent materials for
+which experimental data is not available, the predicted phase-diagrams for the
+K-Mn-O and K-Ti-O systems change dramatically. The demonstrated methodology is
+highly useful for obtaining approximate values on key thermodynamic properties
+in cases where experimental data is hard to obtain, inaccurate or missing.",2305.06828v1
+2023-05-31,Atom-by-atom design of metal oxide catalysts for the oxygen evolution reaction with machine learning,"Green hydrogen production is crucial for a sustainable future, but current
+catalysts for the oxygen evolution reaction (OER) suffer from slow kinetics,
+despite many efforts to produce optimal designs, particularly through the
+calculation of descriptors for activity. In this study, we develop a dataset of
+density functional theory calculations of bulk and surface perovskite oxides,
+and adsorption energies of OER intermediates, which includes compositions up to
+quaternary and facets up to (555). We demonstrate that per-site properties of
+perovskite oxides such as Bader charge or band center can be tuned through
+element substitution and faceting, and develop a machine learning model that
+accurately predicts these properties directly from the local chemical
+environment. We leverage these per-site properties to identify promising
+perovskites with high theoretical OER activity. The identified design
+principles and promising new materials provide a roadmap for closing the gap
+between current artificial catalysts and biological enzymes.",2305.19930v1
+2023-05-31,"Thermodynamic, Kinetic and Mechanical Modeling to Evaluate CO2-induced Corrosion via Oxidation and Carburization in Fe, Ni alloys","A computational framework integrating thermodynamics, kinetics, and
+mechanical stress calculations is developed to study supercritical CO2 induced
+corrosion in model Fe-based MA956 and Ni-based H214 alloys. Empirical models
+parametrized using experimental data show surface oxidation and sub-surface
+carburization for a wide range of thermodynamic conditions (800-1200 {\deg}C,
+1-250 bar). CALPHAD simulations based on empirical models demonstrate higher
+carburization resistance in H214 compared to MA956 below 900 {\deg}C and
+through-thickness carburization in both alloys at higher temperatures. Finite
+element modeling reveals enhanced volumetric misfit induced stresses at oxide
+and carbide interfaces, and its critical dependence on the carbide chemistry
+and concentration.",2306.00106v1
+2023-06-01,Oxide perovskite BaSnO3: A promising high-temperature thermoelectric material for transparent conducting oxides,"The new technology of energy conversion must be developed to ensure energy
+sustainability. Thermoelectric (TE) materials provide an effective means to
+solve the energy crisis. As a potential TE candidate, the TE properties of
+perovskite have received extensively attention. We here investigate the TE
+transport properties of the transparent conducting oxide (TCO) BaSnO3 by
+first-principles calculations. We find that the BaSnO3 perovskite exhibits
+outstanding dynamic and thermal stabilities, which provide excellent electronic
+and thermal transport properties simultaneously. These properties contribute to
+the remarkable Seebeck coefficient and power factor, which gives rise to the ZT
+of n-0.37 and p-1.52 at 900 K. Additionally, doping and nanostructure open
+prospects for effectively improving the TE properties of BaSnO3. Our work
+provides a basis for further optimizing the TE transport properties of cubic
+BaSnO3 and may have worthwhile practical significance for applying cubic
+perovskite to the high-temperature thermoelectric field.",2306.00320v2
+2023-06-14,Metastable Cation-Disordered Niobium Tungsten Oxides as Li-ion Battery Anode Materials,"Metastable cation-disordered compounds have greatly expanded the
+synthesizable compositions of solid-state materials and drawn sharp attention
+among battery electrochemists. While such a strategy has been very successful
+in a few well-known structures, such as rock salts, metastable
+cation-disordered materials for other structural types, especially for
+non-close packed structures, are peculiarly underexplored. In this work, we
+develop a new series of fully cation-disordered metastable niobium tungsten
+oxides with a simple structure, and name this new structural type anti-Li3N.
+Furthermore, we find that metastable anti-Li3N NWOs transform to a
+cation-disordered cubic structure when applied as a Li-ion battery anode,
+highlighting an intriguing non-close packed to close packed conversion between
+two cation-disordered phases, as evidenced in various physicochemical
+characterizations, in terms of diffraction, electronic, and vibrational
+structures. This work enriches the structural and compositional space of
+niobium tungsten oxide families, cation-disordered solid-state materials, and
+the working mechanisms of Li-ion battery anodes.",2306.08735v1
+2023-06-19,"Oxidation, Reduction and Semi-Classical Limit for Quantum Matrix Geometries","Matrix configurations define noncommutative spaces endowed with extra
+structure including a generalized Laplace operator, and hence a metric
+structure. Made dynamical via matrix models, they describe rich physical
+systems including noncommutative gauge theory and emergent gravity. Refining
+the construction in [1], we construct a semi-classical limit through an
+immersed submanifold of complex projective space based on quasi-coherent
+states. We observe the phenomenon of oxidation, where the resulting
+semi-classical space acquires spurious extra dimensions. We propose to remove
+this artifact by passing to a leaf of a carefully chosen foliation, which
+allows to extract the geometrical content of the noncommutative spaces. This is
+demonstrated numerically via multiple examples.",2306.10771v2
+2023-06-23,Quantifying Defects and Finite Size Effects in Graphene Oxide Models,"Oxidation of graphite and subsequent exfoliation leads to single layer
+graphene oxide (GO). GO has found many applications across diverse fields
+including medicinal chemistry, catalysis as well as a precursor for graphene.
+One of the key structural features of GO is the presence of different kinds of
+defects. Molecular dynamics simulations with ReaxFF force fields have been
+widely used to model realistic representations of GO that include defects of
+various types. In these simulations, one can vary the extent and distribution
+of the defects by changing the initial O/C ratio. It is therefore very
+important to employ a proper measure of the defect density. Traditionally, the
+total number of non-graphitic carbon atoms have been employed to quantify the
+amount of defects. Our simulations suggest that this parameter may not be a
+good measure at low defect densities. Herein, we introduce a hitherto
+unexplored metric, relative area of the defects, to gauge the defect density.
+We show that this metric has desirable properties at both low and high defect
+densities. Additionally, we investigate the changes in the defect distribution
+and mechanical properties upon varying the size of the simulation cell.",2306.13457v1
+2023-07-07,Mechanical Properties of Silicon Nanowires with Native Oxide Surface State,"Silicon nanowires have attracted considerable interest due to their
+wide-ranging applications in nanoelectromechanical systems and nanoelectronics.
+Molecular dynamics simulations are powerful tools for studying the mechanical
+properties of nanowires. However, these simulations encounter challenges in
+interpreting the mechanical behavior and brittle to ductile transition of
+silicon nanowires, primarily due to surface effects such as the assumption of
+an unreconstructed surface state. This study specifically focuses on the
+tensile deformation of silicon nanowires with a native oxide layer, considering
+critical parameters such as cross-sectional shape, length-to-critical dimension
+ratio, temperature, the presence of nano-voids, and strain rate. By
+incorporating the native oxide layer, the article aims to provide a more
+realistic representation of the mechanical behavior for different critical
+dimensions and crystallographic orientations of silicon nanowires. The findings
+contribute to the advancement of knowledge regarding size-dependent elastic
+properties and strength of silicon nanowires.",2307.03650v2
+2023-08-12,Initial demonstration of AlGaAs-GaAsP-beta-Ga2O3 n-p-n double heterojunctions,"Beta phase gallium oxides, an ultrawide-bandgap semiconductor, has great
+potential for future power and RF electronics applications but faces challenges
+in bipolar device applications due to the lack of p-type dopants. In this work,
+we demonstrate monocrystalline AlGaAs_GaAsP_beta phase gallium oxides n-p-n
+double-heterojunctions, synthesized using semiconductor grafting technology. By
+transfer printing an n-AlGaAs_p-GaAsP nanomembrane to the n-beta
+phase-Ga$_2$O$_3$ epitaxial substrate, we simultaneously achieved AlGaAs_GaAsP
+epitaxial n-p junction diode with an ideality factor of 1.29 and a
+rectification ratio of 2.57E3 at +/- 2 V, and grafted GaAsP_beta_phase_gallium
+oxides p-n junction diode exhibiting an ideality factor of 1.36 and a
+rectification ratio of 4.85E2 at +/- 2 V.",2308.06575v2
+2023-09-05,Controlling Spontaneous Orientation Polarization in Organic Semiconductors -- The Case of Phosphine Oxides,"Upon film growth by physical vapor deposition, the preferential orientation
+of polar organic molecules can result in a non-zero permanent dipole moment
+(PDM) alignment, causing a macroscopic film polarization. This effect, known as
+spontaneous orientation polarization (SOP), was studied in the case of
+different phosphine oxides. We investigate the control of SOP by molecular
+design and film-growth conditions. Our results show that using less polar
+phosphine oxides with just one phosphor-oxygen bond yields an exceptionally
+high degree of SOP with the so-called giant surface potential (slope) reaching
+more than 150mV/nm in a neat BCPO film grown at room temperature. Additionally,
+by altering the evaporation rate and the substrate temperature, we are able to
+control the SOP magnitude over a broad range from 0 to almost 300mV/nm.
+Diluting BCPO in a non-polar host enhances the PDM alignment only marginally,
+but combining temperature control together with dipolar doping can result in
+almost perfectly aligned molecules with more than 80% of their PDMs standing
+upright on the substrate on average.",2309.02261v2
+2023-10-02,Thermoelectric properties of high-entropy wolframite oxide: (CoCuNiFeZn)$_{1-x}$Ga$_x$WO$_4$,"In this report, the synthesis of high-entropy wolframite oxide
+(CoCuNiFeZn)$_{1-x}$Ga$_x$WO$_4$ through standard solid-state route followed by
+spark plasma sintering (SPS) and their structural, microstructural, and
+thermoelectric properties are investigated. X-ray diffraction pattern followed
+by pattern matching refinement shows monoclinic structure with volume of the
+unit cell decreasing with increasing Ga content. The optical band gap for these
+oxides shows a cocktail effect in high entropy configuration. The Seebeck
+coefficient indicates electrons as dominating charge carriers with a
+non-degenerate behavior. The electrical resistivity decreases with increasing
+temperature depicting a semiconducting nature. Thermal conductivity in
+high-entropy samples ($\kappa\sim$2.1 W/mK @ 300\,K) is significantly lower as
+compared to MgWO$_4$ ($\kappa\sim$11.5 W/mK @ 300\,K), which can be explained
+by the strong phonon scattering due to large lattice disorder in high entropy
+configuration. The thermoelectric figure of merit zT increases with Ga doping
+via modifying all three thermoelectric parameters positively.",2310.00930v1
+2023-10-05,Electrocatalytic removal of persistent organic contaminants at molybdenum doped manganese oxide coated TiO2 nanotube-based anode,"Electrooxidation is an attractive technique that can be effectively applied
+for the treatment of persistent organic contaminants, but its implementation in
+practice is limited by the lack of efficient and low cost anode material that
+would not lead to the generation of chlorinated by products. Herein, we
+developed a novel anode based on TiO2 nanotube array NTA coated with Mo-doped
+MnxOy, and applied it for electrooxidation of persistent organic contaminants.
+The Ti TiO2 NTA MnxOyMo anode outperformed the commercial Ti IrOxPt anode and
+effectively oxidized organic contaminants, with a significantly reduced
+electric energy per order, and avoiding chlorine evolution reaction. Mo doping
+played a key role in the excellent performance of the synthesized anode as it
+favored the formation of oxygen vacancies in the host lattice and Mn and Mo
+species redox couples, which increased the oxidizing power of the anode and
+ensured its complete stability.",2310.03390v1
+2023-10-07,Numerical simulation of defect states and electron transport mechanisms in amorphous oxide thin film transistors,"Physics based numerical simulation has been carried out to probe the sub-gap
+density of states (DOS) and underlying electron transport properties of
+amorphous oxide based thin film transistors (TFTs). The DOS model of TFTs
+consists of exponential band tails, Gaussian shallow donor levels and deep
+acceptor states. Electrical transport and various TFT performance parameters
+are found to be critically dependent on the sub-gap DOS. At low gate bias, when
+Fermi level lies below the conduction band mobility edge, defect states
+mediated trap limited conduction is found to be the dominant transport
+mechanism. However, at relatively higher gate bias, percolation conduction
+above the mobility edge becomes prevalent. Such possible crossover of electron
+transport is well corroborated by gate bias dependent band bending and induced
+free electron density in the channel layer. Such studies are important to
+unravel the critical role of sub-gap DOS on the electrical performance and
+charge transport processes of disordered amorphous oxide TFTs.",2310.04707v2
+2023-09-01,Insight into the melt processed Polylimonene oxide/Polylactic acid blends,"In this work, the polymerization of limonene oxide (LO) has been optimized at
+room temperature with two different aluminium-based catalysts
+[AlMeX{2,6-(CHPh$_2$)$_2$-4-tBu-C$_6$H$_2$O}] (X = Me (1), Cl (2)). A fully
+bio-based ether, polylimonene oxide (PLO), has been synthesized with low
+molecular weight and good thermal stability, being a potential sustainable
+polymeric additive for other bio-based and biodegradable polymers such as
+polylactic acid (PLA). Hence, we have explored its ability to influence the
+thermal, mechanical and morphological properties of PLA by preparing their
+blends by melt processing. The addition of a low amount of PLO led to a nearly
+10 $^\circ$C decrease in the PLA glass transition temperature. Moreover, a
+decrease in the PLA melting temperature and the degree of crystallinity was
+observed. Interestingly, a remarkable increase in the flexibility of PLA-based
+films was noticed. All the results point to the existence of strong
+interactions between the components, suggesting their partial miscibility.",2310.08590v1
+2023-10-27,AFLOW-CCE for the thermodynamics of ionic materials,"Accurate thermodynamic stability predictions enable data-driven computational
+materials design. Standard density functional theory (DFT) approximations have
+limited accuracy with average errors of a few hundred meV/atom for ionic
+materials such as oxides and nitrides. Thus, insightful correction schemes as
+given by the coordination corrected enthalpies (CCE) method, based on an
+intuitive parameterization of DFT errors with respect to coordination numbers
+and cation oxidation states present a simple, yet accurate solution to enable
+materials stability assessments. Here, we illustrate the computational
+capabilities of our AFLOW-CCE software by utilizing our previous results for
+oxides and introducing new results for nitrides. The implementation reduces the
+deviations between theory and experiment to the order of the room temperature
+thermal energy scale, i.e. ~25 meV/atom. The automated corrections for both
+materials classes are freely available within the AFLOW ecosystem via the
+AFLOW-CCE module, requiring only structural inputs.",2310.18187v1
+2023-11-03,Schottky photodetectors with transparent conductive oxides for photonic integrated circuits,"Silicon photonics has many attractive features but faces a major issue:
+inefficient and slow photodetection in the telecom range. New
+metal-semiconductor Schottky photodetectors based on intraband absorption
+address this problem, but their efficiency remains low. We suggest that by
+creating a junction between silicon and a transparent oxide with appropriate
+doping, which results in a real permittivity close to zero (known as the
+epsilon near zero or ENZ regime), detection efficiency could increase by more
+than tenfold. Using Aluminum Zinc Oxide (AZO) as an example, we design an
+optimized AZO/Si slot photonic waveguide detector that could potentially reach
+an efficiency of several tens of percent, in contrast to a few percent for a
+metal/Si Schottky detector. This increase is primarily due to the lower density
+of states in AZO compared to metal, along with superior coupling efficiency and
+strong absorption within a 10 nm slot.",2311.01643v1
+2023-12-04,In-situ tuning of optomechanical crystals with nano-oxidation,"Optomechanical crystals are a promising device platform for quantum
+transduction and sensing. Precise targeting of the optical and acoustic
+resonance frequencies of these devices is crucial for future advances on these
+fronts. However, fabrication disorder in these wavelength-scale nanoscale
+devices typically leads to inhomogeneous resonance frequencies. Here we achieve
+in-situ, selective frequency tuning of optical and acoustic resonances in
+silicon optomechanical crystals via electric field-induced nano-oxidation using
+an atomic-force microscope. Our method can achieve a tuning range >2 nm (0.13%)
+for the optical resonance wavelength in the telecom C-band, and >60 MHz (1.2%)
+for the acoustic resonance frequency at 5 GHz. The tuning resolution of 1.1 nm
+for the optical wavelength, and $150$ kHz for the acoustic frequency allows us
+to spectrally align multiple optomechanical crystal resonators using optimal
+oxidation patterns determined via an inverse design protocol. Our results
+establish a method for precise post-fabrication tuning of optomechancical
+crystals. This technique can enable coupled optomechanical resonator arrays,
+scalable resonant optomechanical circuits, and frequency matching of
+microwave-optical quantum transducers.",2312.02123v1
+2024-01-10,Origin of discrete electrical switching in chemically heterogeneous vanadium oxide crystals,"Electrically driven insulator-metal transitions in prototypical quantum
+materials such as VO2 offer a foundational platform for designing novel
+solid-state devices. Tuning the V: O stoichiometry offers a vast electronic
+phase space with non-trivial collective properties. Here, we report the
+discovery of discrete threshold switching voltages with constant threshold
+voltage difference between cycles in vanadium oxide crystals. The observed
+threshold fields over 10000 cycles are ~100X lower than that noted for
+stoichiometric VO2 and show unique discrete behaviour. We correlate the
+observed discrete memristor behaviour with the valence change mechanism and
+fluctuations in the chemical composition of spatially distributed VO2-VnO2n-1
+complex oxide phases. Design of chemical heterogeneity in Mott insulators,
+therefore, offers an intriguing path to realizing low-energy neuromorphic
+devices.",2401.05222v1
+2024-01-16,Formation of yttrium oxalate phase filled by carbon clusters on the surface of yttrium oxide films,"In the current paper, we report the results of surface modification of cubic
+Y2O3 films employing carbon-ion implantation. The characterization results
+demonstrate the formation of a stable yttrium oxalate-based structure with
+cavities filled with carbon clusters. Theoretical simulations demonstrate that
+the incorporation of eighteen-atom carbon clusters into the cavities of
+Y2(C2O4)3 does not lead to valuable changes in the crystal structure of yttrium
+oxalate. X-ray diffraction and optical measurements demonstrate that the
+subsurface bulk area of cubic yttrium oxide remains unperturbed. The oxalate
+""skin"" thickness with embedded carbon clusters is estimated to be approximately
+10 nm. The prospective employing the method to manage optical properties and
+increase the biocompatibility of yttria and lanthanide oxides are discussed.",2401.08459v1
+2024-01-29,High-k gadolinium scandate on Si obtained by high pressure sputtering from metal targets and in-situ plasma oxidation,"This article studies the physical and electrical behavior of Gd2-xScxO3
+layers grown by high pressure sputtering from metallic Gd and Sc targets. The
+aim is to obtain a high permittivity dielectric for microelectronic
+applications. The films were obtained by the deposition of a metallic
+nanolaminate of Gd and Sc alternating layers, which is afterwards in-situ
+oxidized by plasma. The oxide films obtained were close to stoichiometry,
+amorphous and with minimal interfacial regrowth. By fabricating
+metal-insulator-semiconductor capacitors we found that a moderate temperature
+annealing is needed to enhance permittivity, which reaches a high value of 32
+while keeping moderate leakage. Finally, the feasibility of interface
+scavenging in this material with Ti gate electrodes is also demonstrated.",2401.17332v1
+2024-02-06,Formation of a boron-oxide termination for the (100) diamond surface,"A boron-oxide termination of the diamond (100) surface has been formed by
+depositing molecular boron oxide $\rm{B_2O_3}$ onto the hydrogen-terminated
+(100) diamond surface under ultrahigh vacuum conditions and annealing to
+$\rm{950^{\circ} C}$. The resulting termination was highly oriented and
+chemically homogeneous, although further optimisation is required to increase
+the surface coverage beyond the 0.4 ML achieved here. This work demonstrates
+the possibility of using molecular deposition under ultrahigh vacuum conditions
+for complex surface engineering of the diamond surface, and may be a first step
+in an alternative approach to fabricating boron doped delta layers in diamond.",2402.03940v2
+2024-02-13,Coexistence and interplay of two ferroelectric mechanisms in Zn1-xMgxO,"Ferroelectric materials promise exceptional attributes including low power
+dissipation, fast operational speeds, enhanced endurance, and superior
+retention to revolutionize information technology. However, the practical
+application of ferroelectric-semiconductor memory devices has been
+significantly challenged by the incompatibility of traditional perovskite oxide
+ferroelectrics with metal-oxide-semiconductor technology. Recent discoveries of
+ferroelectricity in binary oxides such as Zn1-xMgxO and Hf1-xZrxO have been a
+focal point of research in ferroelectric information technology. This work
+investigates the ferroelectric properties of Zn1-xMgxO utilizing automated band
+excitation piezoresponse force microscopy. Our findings reveal the coexistence
+of two ferroelectric subsystems within Zn1-xMgxO. We propose a ""fringing-ridge
+mechanism"" of polarization switching that is characterized by initial lateral
+expansion of nucleation without significant propagation in depth, contradicting
+the conventional domain growth process observed in ferroelectrics. This unique
+polarization dynamics in Zn1-xMgxO suggests a new understanding of
+ferroelectric behavior, contributing to both the fundamental science of
+ferroelectrics and their application in information technology.",2402.08852v1
+2024-02-29,Variability mitigation in epitaxial-heterostructure-based spin qubit devices via gate layout optimization,"The scalability of spin qubit devices is conditioned by qubit-to-qubit
+variability. Disorder in the host materials indeed affects the wave functions
+of the confined carriers, which leads to variations in their charge and spin
+properties. Charge disorder in the amorphous oxides is particularly detrimental
+owing to its long-range influence. Here we analyze the effects of charge traps
+at the semiconductor/oxide interface, which are generally believed to play a
+dominant role in variability. We consider multiple random distributions of
+these interface traps and numerically calculate their impact on the chemical
+potentials, detuning and tunnel coupling of two adjacent quantum dots in SiGe
+heterostructure. Our results highlight the beneficial screening effect of the
+metal gates. The surface of the heterostructure shall, therefore, be covered as
+much as possible by the gates in order to limit variability. We propose an
+alternative layout with tip-shaped gates that maximizes the coverage of the
+semiconductor/oxide interface and outperforms the usual planar layout in some
+regimes. This highlights the importance of design in the management of
+device-to-device variability.",2402.18991v1
+2024-03-04,Spectroscopic investigations on trivalent ruthenium ions in ruthenium perovskite oxide thin films,"The $d^5$ electron configurations under the crystal field, spin-orbit
+coupling, and Coulomb interaction give rise to a plethora of profound ground
+states. Ruthenium perovskite oxides exhibit a number of unconventional
+properties yet the Ru$^{4+}$ state ($4d^4$) is usually stable in these
+materials. In this regard, Ru$^{3+}$ ions in perovskite materials are expected
+to be a mesmerising playground of $4d^5$ electron configurations. Here, we
+report measurements of x-ray photoemission spectroscopy on recently synthesized
+perovskite ruthenium oxide thin films, LaRuO$_3$ and NdRuO$_3$, whose valence
+state of the ruthenium ions is trivalent. We discuss correlation and spin-orbit
+effects from the valence-band spectra, in particular an additional peak
+structure around 3-5 eV, reminiscent of the so-called 3 eV peak observed in
+Sr$_2$RuO$_4$. Moreover, we find that the core-level spectra of these materials
+are quantitatively different from those in other ruthenates which possess
+Ru$^{4+}$ ions, e.g., SrRuO$_3$. We therefore argue that the core level spectra
+of LaRuO$_3$ and NdRuO$_3$ are peculiar to the Ru$^{3+}$ states.",2403.01853v1
+2024-03-19,Large Rashba spin-orbit coupling in metallic SrTaO$_3$ thin films,"Epitaxial thin films of SrTaO$_3$ with thickness ($t$) smaller than 74 nm
+were successfully fabricated on an insulator
+(LaAlO$_3$)$_{0.3}$(Sr$_2$AlTaO$_6$)$_{0.7}$ substrate. Films with $t$ above
+8.6 nm showed metallic conduction. Both conductivity and a mobility showed a
+decrease with increasing $t$ above 42 nm, suggesting the instability of thick
+SrTaO$_3$ films. This instability was also supported by TEM image and XRD
+intensity. For the metallic films with $t$ below 25 nm, energy band splitting
+due to spin-orbit coupling ($\Delta$$_{so}$) and Rashba parameter
+($\alpha$$_R$) were deduced from an analysis of a magnetoresistance using
+two-dimensional weak antilocalization theory. The values of $\Delta$$_{so}$
+ranged from 26 to 120 meV, which were the largest among other metallic oxide
+films, such as SrNbO$_3$, SrIrO$_3$, and La$_{2/3}$Sr$_{1/3}$MnO$_3$ thin
+films, indicating that spin-orbit coupling in SrTaO$_3$ was the largest among
+the metallic perovskite oxides reported so far. The values of $\alpha$$_R$ for
+our SrTaO$_3$ films ranged from $8.8 \times$10$^{-13}$ to $1.7
+\times$10$^{-12}$ eV m, which were much larger than those reported for other
+metallic oxide thin films.",2403.12612v1
+2024-04-07,Morphological stability of electrostrictive thin films,"A large electric field is typically present in anodic or passive oxide films.
+Stresses induced by such a large electric field are critical in understanding
+the breakdown mechanism of thin oxide films and improving their corrosion
+resistance. In this work, we consider electromechanical coupling through the
+electrostrictive effect. A continuum model incorporating lattice misfit and
+electric field-induced stresses is developed. We perform a linear stability
+analysis of the full coupled model and show that, for typical oxides,
+neglecting electrostriction underestimates the film's instability, especially
+in systems with a large electric field. Moreover, a region where
+electrostriction can potentially provide a stabilizing effect is identified,
+allowing electrostriction to enhance corrosion resistance. We identified an
+equilibrium electric field intrinsic to the system and the corresponding
+equilibrium film thickness. The film's stability is very sensitive to the
+electric field: a 40 percent deviation from the equilibrium electric field can
+change the maximum growth rate by nearly an order of magnitude. Moreover, our
+model reduces to classical morphological instability models in the limit of
+misfit-only, electrostatic-only, and no-electrostriction cases. Finally, the
+effect of various parameters on the film's stability is studied.",2404.05093v1
+2023-08-18,The SPARC Toroidal Field Model Coil Program,"The SPARC Toroidal Field Model Coil (TFMC) Program was a three-year effort
+between 2018 and 2021 that developed novel Rare Earth Yttrium Barium Copper
+Oxide (REBCO) superconductor technologies and then successfully utilized these
+technologies to design, build, and test a first-in-class, high-field (~20 T),
+representative-scale (~3 m) superconducting toroidal field coil. With the
+principal objective of demonstrating mature, large-scale, REBCO magnets, the
+project was executed jointly by the MIT Plasma Science and Fusion Center (PSFC)
+and Commonwealth Fusion Systems (CFS). The TFMC achieved its programmatic goal
+of experimentally demonstrating a large-scale high-field REBCO magnet,
+achieving 20.1 T peak field-on-conductor with 40.5 kA of terminal current, 815
+kN/m of Lorentz loading on the REBCO stacks, and almost 1 GPa of mechanical
+stress accommodated by the structural case. Fifteen internal demountable
+pancake-to-pancake joints operated in the 0.5 to 2.0 nOhm range at 20 K and in
+magnetic fields up to 12 T. The DC and AC electromagnetic performance of the
+magnet, predicted by new advances in high-fidelity computational models, was
+confirmed in two test campaigns while the massively parallel, single-pass,
+pressure-vessel style coolant scheme capable of large heat removal was
+validated. The REBCO current lead and feeder system was experimentally
+qualified up to 50 kA, and the crycooler based cryogenic system provided 600 W
+of cooling power at 20 K with mass flow rates up to 70 g/s at a maximum design
+pressure of 20 bar-a for the test campaigns. Finally, the feasibility of using
+passive, self-protection against a quench in a fusion-scale NI TF coil was
+experimentally assessed with an intentional open-circuit quench at 31.5 kA
+terminal current.",2308.12301v1
+2022-04-18,The long-term evolution of the atmosphere of Venus: processes and feedback mechanisms,"This work reviews the long-term evolution of the atmosphere of Venus, and
+modulation of its composition by interior-exterior cycling. The formation and
+evolution of Venus's atmosphere, leading to contemporary surface conditions,
+remain hotly debated topics, and involve questions that tie into many
+disciplines. We explore these various inter-related mechanisms which shaped the
+evolution of the atmosphere, starting with the volatile sources and sinks.
+Going from the deep interior to the top of the atmosphere, we describe volcanic
+outgassing, surface atmosphere interactions, and atmosphere escape.
+Furthermore, we address more complex aspects of the history of Venus, including
+the role of Late Accretion impacts, how magnetic field generation is tied into
+long-term evolution, and the implications of geochemical and geodynamical
+feedback cycles for atmospheric evolution. We highlight plausible end-member
+evolutionary pathways that Venus could have followed, from accretion to its
+present-day state, based on modeling and observations. In a first scenario, the
+planet was desiccated by atmospheric escape during the magma ocean phase. In a
+second scenario, Venus could have harbored surface liquid water for long
+periods of time, until its temperate climate was destabilized and it entered a
+runaway greenhouse phase. In a third scenario, Venus's inefficient outgassing
+could have kept water inside the planet, where hydrogen was trapped in the core
+and the mantle was oxidized. We discuss existing evidence and future
+observations and missions required to refine our understanding of the planet's
+history and of the complex feedback cycles between the interior, surface, and
+atmosphere that have been operating in the past, present or future of Venus.",2204.08540v2
+2008-04-17,"Aluminum-, Calcium- And Titanium-Rich Oxide Stardust In Ordinary Chondrite Meteorites","We report isotopic data for a total of 96 presolar oxide grains found in
+residues of several unequilibrated ordinary chondrite meteorites. Identified
+grain types include Al2O3, MgAl2O4, hibonite (CaAl12O19) and Ti oxide. This
+work greatly increases the presolar hibonite database, and is the first report
+of presolar Ti oxide. O-isotopic compositions of the grains span previously
+observed ranges and indicate an origin in red giant and asymptotic giant branch
+(AGB) stars of low mass (<2.5 MSun) for most grains. Cool bottom processing in
+the parent AGB stars is required to explain isotopic compositions of many
+grains. Potassium-41 enrichments in hibonite grains are attributable to in situ
+decay of now-extinct 41Ca. Inferred initial 41Ca/40Ca ratios are in good
+agreement with model predictions for low-mass AGB star envelopes, provided that
+ionization suppresses 41Ca decay. Stable Mg and Ca isotopic ratios of most of
+the hibonite grains reflect primarily the initial compositions of the parent
+stars and are generally consistent with expectations for Galactic chemical
+evolution, but require some local interstellar chemical inhomogeneity. Very
+high 17O/16O or 25Mg/24Mg ratios suggest an origin for some grains in binary
+star systems where mass transfer from an evolved companion has altered the
+parent star compositions. A supernova origin for the hitherto enigmatic
+18O-rich Group 4 grains is strongly supported by multi-element isotopic data
+for two grains. The Group 4 data are consistent with an origin in a single
+supernova in which variable amounts of material from the deep 16O-rich interior
+mixed with a unique end-member mixture of the outer layers. The Ti oxide grains
+primarily formed in low-mass AGB stars. They are smaller and rarer than
+presolar Al2O3, reflecting the lower abundance of Ti than Al in AGB envelopes.",0804.2866v1
+2009-07-08,Charge Distribution Near Oxygen Vacancies in Reduced Ceria,"Understanding the electronic charge distribution around oxygen vacancies in
+transition metal and rare earth oxides is a scientific challenge of
+considerable technological importance. We show how significant information
+about the charge distribution around vacancies in cerium oxide can be gained
+from a study of high resolution crystal structures of higher order oxides which
+exhibit ordering of oxygen vacancies. Specifically, we consider the
+implications of a bond valence sum analysis of Ce$_{7}$O$_{12}$ and
+Ce$_{11}$O$_{20}$. To illuminate our analysis we show alternative
+representations of the crystal structures in terms of orderly arrays of
+co-ordination defects and in terms of flourite-type modules. We found that in
+Ce$_{7}$O$_{12}$, the excess charge resulting from removal of an oxygen atom
+delocalizes among all three triclinic Ce sites closest to the O vacancy. In
+Ce$_{11}$O$_{20}$, the charge localizes on the next nearest neighbour Ce atoms.
+Our main result is that the charge prefers to distribute itself so that it is
+farthest away from the O vacancies. This contradicts \emph{the standard picture
+of charge localisation} which assumes that each of the two excess electrons
+localises on one of the cerium ions nearest to the vacancy. This standard
+picture is assumed in most calculations based on density functional theory
+(DFT). Based on the known crystal structure of Pr$_{6}$O$_{11}$, we also
+predict that the charge in Ce$_{6}$O$_{11}$ will be found in the second
+coordination shell of the O vacancy. Although this review focuses on bulk
+cerium oxides our approach to characterising electronic properties of oxygen
+vacancies and the physical insights gained should also be relevant to surface
+defects and to other rare earth and transition metal oxides.",0907.1320v3
+2012-10-01,Investigation of X-ray induced radiation damage at the Si-SiO2 interface of silicon sensors for the European XFEL,"Experiments at the European X-ray Free Electron Laser (XFEL) require silicon
+pixel sensors which can withstand X-ray doses up to 1 GGy. For the
+investigation of X-ray radiation damage up to these high doses, MOS capacitors
+and gate-controlled diodes built on high resistivity n-doped silicon with
+crystal orientations <100> and <111> produced by two vendors, CiS and
+Hamamatsu, have been irradiated with 12 keV X-rays at the DESY DORIS III
+synchrotron light source. Using capacitance/conductance-voltage,
+current-voltage and thermal dielectric relaxation current measurements, the
+surface densities of oxide charges and interface traps at the Si-SiO2
+interface, and the surface-current densities have been determined as function
+of dose. Results indicate that the dose dependence of the surface density of
+oxide charges and the surface-current density depend on the crystal orientation
+and producer. In addition, the influence of the voltage applied to the gates of
+the MOS capacitor and the gate-controlled diode during X-ray irradiation on the
+surface density of oxide charges and the surface-current density has been
+investigated at doses of 100 kGy and 100 MGy. It is found that both strongly
+depend on the gate voltage if the electric field in the oxide points from the
+surface of the SiO2 to the Si-SiO2 interface. Finally, annealing studies have
+been performed at 60 and 80 degree C on MOS capacitors and gate-controlled
+diodes irradiated to 5 MGy and the annealing kinetics of oxide charges and
+surface current determined.",1210.0427v3
+2017-03-17,Effects of Dielectric Stoichiometry on the Photoluminescence Properties of Encapsulated WSe2 Monolayers,"Two-dimensional transition-metal-dichalcogenide semiconductors have emerged
+as promising candidates for optoelectronic devices with unprecedented
+properties and ultra-compact performances. However atomically thin materials
+are highly sensitive to surrounding dielectric media, which imposes severe
+limitations to their practical applicability. Hence for their suitable
+integration into devices, the development of reliable encapsulation procedures
+that preserve their physical properties are required. Here, the excitonic
+photoluminescence of WSe2 monolayer flakes is assessed, at room temperature and
+10 K, on mechanically exfoliated flakes encapsulated with SiOx and AlxOy layers
+employing chemical and physical deposition techniques. Conformal flakes coating
+on untreated - non-functionalized - flakes is successfully demonstrated by all
+the techniques except for atomic layer deposition, where a cluster-like oxide
+coating is observed. No significant compositional or strain state changes in
+the flakes are detected upon encapsulation by any of the techniques.
+Remarkably, our results evidence that the flakes' optical emission is strongly
+influenced by the quality of the encapsulating oxide - stoichiometry -. When
+the encapsulation is carried out with slightly sub-stoichiometric oxides two
+remarkable phenomena are observed. First, there is a clear electrical doping of
+the monolayers that is revealed through a dominant trion - charged exciton -
+room-temperature photoluminescence. Second, a strong decrease of the monolayers
+optical emission is measured attributed to non-radiative recombination
+processes and/or carriers transfer from the flake to the oxide. Power- and
+temperature-dependent photoluminescence measurements further confirm that
+stoichiometric oxides obtained by physical deposition lead to a successful
+encapsulation.",1703.06186v3
+2020-07-01,Predicting Oxidation and Spin States by High-Dimensional Neural Networks: Applications to Lithium Manganese Oxide Spinels,"Lithium ion batteries often contain transition metal oxides like
+Li$_{x}$Mn$_2$O$_4$ ($0\leq x\leq2$). Depending on the Li content different
+ratios of Mn$^\text{III}$ to Mn$^\text{IV}$ ions are present. In combination
+with electron hopping the Jahn-Teller distortions of the Mn$^\text{III}$O$_6$
+octahedra can give rise to complex phenomena like structural transitions and
+conductance. While for small model systems oxidation and spin states can be
+determined using density functional theory (DFT), the investigation of
+dynamical phenomena by DFT is too demanding. Previously, we have shown that a
+high-dimensional neural network potential can extend molecular dynamics (MD)
+simulations of Li$_{x}$Mn$_2$O$_4$ to nanosecond time scales, but these
+simulations did not provide information about the electronic structure. Here we
+extend the use of neural networks to the prediction of atomic oxidation and
+spin states. The resulting high-dimensional neural network is able to predict
+the spins of the Mn ions with an error of only 0.03 $\hbar$. We find that the
+Mn e$_\text{g}$ electrons are correctly conserved and that the number of
+Jahn-Teller distorted Mn$^\text{III}$O$_6$ octahedra is predicted precisely for
+different Li loadings. A charge ordering transition is observed between 280 and
+300 K, which matches resistivity measurements. Moreover, the activation energy
+of the electron hopping conduction above the phase transition is predicted to
+be 0.18 eV deviating only 0.02 eV from experiment. This work demonstrates that
+machine learning is able to provide an accurate representation of both, the
+geometric and the electronic structure dynamics of Li$_x$Mn$_2$O$_4$, on time
+and length scales that are not accessible by ab initio MD.",2007.00335v2
+2015-12-30,Computationally Designed Zirconium Organometallic Catalyst for Direct Epoxidation of Alkenes without Allylic H Atoms: Aromatic Linkage Eliminates Formation of Inert Octahedral Complexes,"We used density functional theory to computationally design a Zr
+organometallic catalyst for selectively oxidizing substrates using molecular
+oxygen as oxidant without coreductant. Each selective oxidation cycle involves
+four general steps: (a) a peroxo or weakly adsorbed O2 group releases an O atom
+to substrate to form substrate oxide and an oxo group, (b) an oxygen molecule
+adds to the oxo group to generate an eta2-ozone group, (c) the eta2-ozone group
+rearranges to form an eta3-ozone group, and (d) the eta3-ozone group releases
+an O atom to substrate to form substrate oxide and regenerate the peroxo or
+weakly adsorbed O2 group. This catalyst could potentially be synthesized via
+the condensation reaction Zr(N(R)R')4 + 2
+C6H4-1,6-(N(C6H3-2',6'-(CH(CH3)2)2)OH)2 -->
+Zr(C6H4-1,6-(N(C6H3-2',6'-(CH(CH3)2)2)O)2)2 [aka Zr_Benzol catalyst] + 4
+N(R)(R')H where R and R' are CH3, CH2CH3, or other alkyl groups. For direct
+ethylene epoxidation, the computed enthalpic energetic span (i.e., effective
+activation energy for the entire catalytic cycle) is 27.1 kcal/mol, which is
+one of the lowest values for catalysts studied to date. We study reaction
+mechanisms and the stability of different catalyst forms as a function of the
+oxygen atom chemical potential. Notably, an aromatic linkage in each ligand
+prevents this catalyst from deactivating to form an inactive octahedral-like
+structure that contains the same atoms as the dioxo complex, Zr(Ligand)2(O)2.
+Due to a side reaction that can transfer an allylic H atom from alkene to
+catalyst, this catalyst is useful for directly epoxidizing alkenes such as
+ethylene that do not contain allylic H atoms. To better understand the reaction
+chemistry, we computed net atomic charges and bond orders for the two
+catalytically relevant reaction cycles. These results quantify electron
+transfer and bond forming and breaking during the catalytic process.",1512.09372v1
+2016-08-04,Disentangling Vacancy Oxidation on Metallicity-Sorted Carbon Nanotubes,"Pristine single-walled carbon nanotubes (SWCNTs) are rather inert to O$_2$
+and N$_2$, which for low doses chemisorb only on defect sites or vacancies of
+the SWCNTs at the ppm level. However, very low doping has a major effect on the
+electronic properties and conductivity of the SWCNTs. Already at low O$_2$
+doses (80 L), the X-ray photoelectron spectroscopy (XPS) O 1s signal becomes
+saturated, indicating nearly all the SWCNT's vacancies have been oxidized. As a
+result, probing vacancy oxidation on SWCNTs via XPS yields spectra with rather
+low signal-to-noise ratios, even for metallicity-sorted SWCNTs. We show that,
+even under these conditions, the first principles density functional theory
+calculated Kohn-Sham O 1s binding energies may be used to assign the XPS O 1s
+spectra for oxidized vacancies on SWCNTs into its individual components. This
+allows one to determine the specific functional groups or bonding environments
+measured. We find the XPS O 1s signal is mostly due to three O-containing
+functional groups on SWCNT vacancies: epoxy (C$_2$$>$O), carbonyl
+(C$_2$$>$C$=$O), and ketene (C$=$C$=$O), as ordered by abundance. Upon
+oxidation of nearly all the SWCNT's vacancies, the central peak's intensity for
+the metallic SWCNT sample is 60\% greater than for the semiconducting SWCNT
+sample. This suggests a greater abundance of O-containing defect structures on
+the metallic SWCNT sample. For both metallic and semiconducting SWCNTs, we find
+O$_2$ does not contribute to the measured XPS O~1s spectra.",1608.01424v1
+2018-06-04,Predicting the thermodynamic stability of perovskite oxides using machine learning models,"Perovskite materials have become ubiquitous in many technologically relevant
+applications, ranging from catalysts in solid oxide fuel cells to light
+absorbing layers in solar photovoltaics. The thermodynamic phase stability is a
+key parameter that broadly governs whether the material is expected to be
+synthesizable, and whether it may degrade under certain operating conditions.
+Phase stability can be calculated using Density Functional Theory (DFT), but
+the significant computational cost makes such calculation potentially
+prohibitive when screening large numbers of possible compounds. In this work,
+we developed machine learning models to predict the thermodynamic phase
+stability of perovskite oxides using a dataset of more than 1900 DFT-calculated
+perovskite oxide energies. The phase stability was determined using convex hull
+analysis, with the energy above the convex hull (Ehull) providing a direct
+measure of the stability. We generated a set of 791 features based on elemental
+property data to correlate with the Ehull value of each perovskite compound.
+For classification, the extra trees algorithm achieved the best prediction
+accuracy of 0.93 (+/- 0.02), with an F1 score of 0.88 (+/- 0.03). For
+regression, leave-out 20% cross-validation tests with kernel ridge regression
+achieved the minimal root mean square error (RMSE) of 28.5 (+/- 7.5) meV/atom
+between cross-validation predicted Ehull values and DFT calculations, with the
+mean absolute error (MAE) in cross-validation energies of 16.7 (+/- 2.3)
+meV/atom. We further validated our model by predicting the stability of
+compounds not present in the training set and demonstrated our machine learning
+models are a fast and effective means of obtaining qualitatively useful
+guidance for a wide-range of perovskite oxide stability, potentially impacting
+materials design choices in a variety of technological applications.",1806.01038v1
+2019-11-21,Oxidized-monolayer Tunneling Barrier for Strong Fermi-level Depinning in Layered InSe Transistors,"In 2D-semiconductor-based field-effect transistors and optoelectronic
+devices, metal-semiconductor junctions are one of the crucial factors
+determining device performance. The Fermi-level (FL) pinning effect, which
+commonly caused by interfacial gap states, severely limits the tunability of
+junction characteristics, including barrier height and contact resistance. A
+tunneling contact scheme has been suggested to address the FL pinning issue in
+metal-2D-semiconductor junctions, whereas the experimental realization is still
+elusive. Here, we show that an oxidized-monolayer-enabled tunneling barrier can
+realize a pronounced FL depinning in indium selenide (InSe) transistors,
+exhibiting a large pinning factor of 0.5 and a highly modulated Schottky
+barrier height. The FL depinning can be attributed to the suppression of metal-
+and disorder-induced gap states as a result of the high-quality tunneling
+contacts. Structural characterizations indicate uniform and atomically thin
+surface oxidation layer inherent from nature of van der Waals materials and
+atomically sharp oxide-2D-semiconductor interfaces. Moreover, by effectively
+lowering the Schottky barrier height, we achieve an electron mobility of 2160
+cm$^2$/Vs and a contact barrier of 65 meV in two-terminal InSe transistors. The
+realization of strong FL depinning in high-mobility InSe transistors with the
+oxidized monolayer presents a viable strategy to exploit layered semiconductors
+in contact engineering for advanced electronics and optoelectronics.",1911.09327v1
+2019-12-20,"Strong Performance Enhancement in Lead-Halide Perovskite Solar Cells through Rapid, Atmospheric Deposition of n-type Buffer Layer Oxides","Thin (approximately 10 nm) oxide buffer layers grown over lead-halide
+perovskite device stacks are critical for protecting the perovskite against
+mechanical and environmental damage. However, the limited perovskite stability
+restricts the processing methods and temperatures (<=110 C) that can be used to
+deposit the oxide overlayers, with the latter limiting the electronic
+properties of the oxides achievable. In this work, we demonstrate an
+alternative to existing methods that can grow pinhole-free TiOx (x =
+2.00+/-0.05) films with the requisite thickness in <1 min without vacuum. This
+technique is atmospheric pressure chemical vapor deposition (AP-CVD). The rapid
+but soft deposition enables growth temperatures of >=180 {\deg}C to be used to
+coat the perovskite. This is >=70 {\deg}C higher than achievable by current
+methods and results in more conductive TiOx films, boosting solar cell
+efficiencies by >2%. Likewise, when AP-CVD SnOx (x ~ 2) is grown on
+perovskites, there is also minimal damage to the perovskite beneath. The SnOx
+layer is pinhole-free and conformal, which reduces shunting in devices, and
+increases steady-state efficiencies from 16.5% (no SnOx) to 19.4% (60 nm SnOx),
+with fill factors reaching 84%. This work shows AP-CVD to be a versatile
+technique for growing oxides on thermally-sensitive materials.",1912.09850v1
+2020-03-07,"Honeycomb Layered Oxides: Structure, Energy Storage, Transport, Topology and Relevant Insights","The advent of nanotechnology has hurtled the discovery and development of
+nanostructured materials with stellar chemical and physical functionalities in
+a bid to address issues in energy, environment, telecommunications and
+healthcare. In this quest, a class of two-dimensional layered materials
+consisting of alkali or coinage metal atoms sandwiched between slabs
+exclusively made of transition metal and chalcogen (or pnictogen) atoms
+arranged in a honeycomb fashion have emerged as materials exhibiting
+fascinatingly rich crystal chemistry, high-voltage electrochemistry, fast
+cation diffusion besides playing host to varied exotic electromagnetic and
+topological phenomena. Currently, with a niche application in energy storage as
+high-voltage materials, this class of honeycomb layered oxides serves as ideal
+pedagogical exemplars of the innumerable capabilities of nanomaterials drawing
+immense interest in multiple fields ranging from materials science, solid-state
+chemistry, electrochemistry and condensed matter physics. In this review, we
+delineate the relevant chemistry and physics of honeycomb layered oxides, and
+discuss their functionalities for tunable electrochemistry, superfast ionic
+conduction, electromagnetism and topology. Moreover, we elucidate the
+unexplored albeit vastly promising crystal chemistry space whilst outlining
+effective ways to identify regions within this compositional space,
+particularly where interesting electromagnetic and topological properties could
+be lurking within the aforementioned alkali and coinage-metal honeycomb layered
+oxide structures. We conclude by pointing towards possible future research
+directions, particularly the prospective realisation of
+Kitaev-Heisenberg-Dzyaloshinskii-Moriya interactions with single crystals and
+Floquet theory in closely-related honeycomb layered oxide materials.",2003.03555v10
+2020-03-23,Influence of Surface Hydrophilicity and Hydration on the Rotational Relaxation of Supercooled Water on Graphene Oxide Surfaces,"Hydration or interfacial water present in biomolecules and inorganic solids
+have been shown to exhibit a dynamical transition upon supercooling. However,
+an understanding of the extent of the underlying surface hydrophilicity as well
+as the local distribution of hydrophilic/hydrophobic patches on the dynamical
+transition is unexplored. Here, we use molecular dynamics simulations with a
+TIP4P/2005 water model to study translational and rotational relaxation
+dynamics of interfacial water on graphene surfaces. The purpose of this study
+is to investigate the influence of both surface chemistry as well as the extent
+of hydration on the rotational transitions of interfacial water on graphene
+oxide (GO) surfaces in the deeply supercooled region. We have considered three
+graphene-based surfaces; a GO surface with equal proportions of oxidized and
+pristine graphene regions in a striped topology, a fully oxidized surface and a
+pristine graphene surface. The dipole relaxation time of interfacial water
+shows a strong-to-strong, strong, and a fragile-to-strong transition on these
+surfaces, respectively, in the temperature range of 210-298 K. In contrast,
+bulk water shows a fragile-to-strong transition upon supercooling. In all these
+cases at high hydration, interfacial water co-exists with a thick water film
+with bulk-like properties. To investigate the influence of bulk water on
+dynamical transitions, we simulated a low hydration regime where only bound
+water (surface water) is present on the GO surfaces and found that the
+rotational relaxation of surface water on both the GO and fully oxidized
+surfaces show a single Arrhenius behavior. Our results indicate that not only
+does the local extent of surface hydrophilicity play a role in determining the
+energy landscape explored by the water molecules upon supercooling, but the
+presence of bulk water also modulates the dynamic transition.",2003.10515v1
+2020-08-04,Vacuum ultraviolet photoabsorption spectroscopy of space-related ices: 1 keV electron irradiation of nitrogen- and oxygen-rich ices,"Molecular oxygen, nitrogen, and ozone have been detected in the Solar System.
+They are also expected to be present in ice-grain mantles within star-forming
+regions. Laboratory experiments that simulate energetic processing (ions,
+photons, and electrons) of ices are essential for interpreting and directing
+future astronomical observations. We provide VUV photoabsorption spectroscopic
+data of energetically processed nitrogen- and oxygen-rich ices that will help
+to identify absorption bands and/or spectral slopes observed on icy objects in
+the Solar System and on ice-grain mantles of the interstellar medium. We
+present VUV photoabsorption spectra of frozen O2 and N2, a 1:1 mixture of both,
+and a new systematic set of pure and mixed nitrogen oxide ices. Spectra were
+obtained at 22 K before and after 1 keV electron bombardment of the ice sample.
+Ices were then annealed to higher temperatures to study their thermal
+evolution. In addition, Fourier-transform infrared spectroscopy was used as a
+secondary probe of molecular synthesis to better identify the physical and
+chemical processes at play. Our VUV data show that ozone and the azide radical
+(N3) are observed in our experiments after electron irradiation of pure O2 and
+N2 ices, respectively. Energetic processing of an O2:N2 = 1:1 ice mixture leads
+to the formation of ozone along with a series of nitrogen oxides. The electron
+irradiation of solid nitrogen oxides, pure and in mixtures, induces the
+formation of new species such as O2, N2 , and other nitrogen oxides not present
+in the initial ice. Results are discussed here in light of their relevance to
+various astrophysical environments. Finally, we show that VUV spectra of solid
+NO2 and water can reproduce the observational VUV profile of the cold surface
+of Enceladus, Dione, and Rhea, strongly suggesting the presence of nitrogen
+oxides on the surface of the icy Saturn moons.",2008.01783v1
+2020-09-15,Self-formed $LaAlO_3/SrTiO_3$ Micro-Membranes,"Oxide heterostructures represent a unique playground for triggering the
+emergence of novel electronic states and for implementing new device concepts.
+The discovery of 2D conductivity at the $LaAlO_3/SrTiO_3$ interface has been
+linking for over a decade two of the major current research fields in Materials
+Science: correlated transition-metal-oxide systems and low-dimensional systems.
+A full merging of these two fields requires nevertheless the realization of
+$LaAlO_3/SrTiO_3$ heterostructures in the form of freestanding membranes. Here
+we show a completely new method for obtaining oxide hetero-membranes with
+micrometer lateral dimensions. Unlike traditional thin-film-based techniques
+developed for semiconductors and recently extended to oxides, the concept we
+demonstrate does not rely on any sacrificial layer and is based instead on pure
+strain engineering. We monitor through both real-time and post-deposition
+analyses, performed at different stages of growth, the strain relaxation
+mechanism leading to the spontaneous formation of curved hetero-membranes.
+Detailed transmission electron microscopy investigations show that the
+membranes are fully epitaxial and that their curvature results in a huge strain
+gradient, each of the layers showing a mixed compressive/tensile strain state.
+Electronic devices are fabricated by realizing ad hoc circuits for individual
+micro-membranes transferred on silicon chips. Our samples exhibit metallic
+conductivity and electrostatic field effect similar to 2D-electron systems in
+bulk heterostructures. Our results open a new path for adding oxide
+functionality into semiconductor electronics, potentially allowing for
+ultra-low voltage gating of a superconducting transistors, micromechanical
+control of the 2D electron gas mediated by ferroelectricity and
+flexoelectricity, and on-chip straintronics.",2009.06900v2
+2021-02-01,Data-driven Approach to Parameterize SCAN+U for an Accurate Description of 3d Transition Metal Oxide Thermochemistry,"Semi-local DFT methods exhibit significant errors for the phase diagrams of
+transition-metal oxides that are caused by an incorrect description of
+molecular oxygen and the large self-interaction error in materials with
+strongly localized electronic orbitals. Empirical and semiempirical corrections
+based on the DFT+U method can reduce these errors, but the parameterization and
+validation of the correction terms remains an on-going challenge. We develop a
+systematic methodology to determine the parameters and to statistically assess
+the results by considering thermochemical data across a set of transition metal
+compounds. We consider three interconnected levels of correction terms: (1) a
+constant oxygen binding correction, (2) Hubbard-U correction, and (3) DFT/DFT+U
+compatibility correction. The parameterization is expressed as a unified
+optimization problem. We demonstrate this approach for 3d transition metal
+oxides, considering a target set of binary and ternary oxides. With a total of
+37 measured formation enthalpies taken from the literature, the dataset is
+augmented by the reaction energies of 1,710 unique reactions that were derived
+from the formation energies by systematic enumeration. To ensure a balanced
+dataset across the available data, the reactions were grouped by their
+similarity using clustering and suitably weighted. The parameterization is
+validated using leave-one-out cross-validation (CV), a standard technique for
+the validation of statistical models. We apply the methodology to the SCAN
+density functional. Based on the CV score, the error of binary (ternary) oxide
+formation energies is reduced by 40% (75%) to 0.10 (0.03) eV/atom. The method
+and tools demonstrated here can be applied to other classes of materials or to
+parameterize the corrections to optimize DFT+U performance for other target
+physical properties.",2102.01131v2
+2021-04-25,Electronic excitation spectra of cerium oxides: from ab initio dielectric response functions to Monte Carlo charge transport simulations,"Nanomaterials made of the cerium oxides CeO$_2$ and Ce$_2$O$_3$ have a broad
+range of applications, from catalysts in automotive, industrial or energy
+operations to promising materials to enhance hadrontherapy effectiveness in
+oncological treatments. To elucidate the physico-chemical mechanisms involved
+in these processes, it is of paramount importance to know the electronic
+excitation spectra of these oxides, which are obtained here through
+high-accuracy linear-response time-dependent density functional theory
+calculations. In particular, the macroscopic dielectric response functions
+$\bar\epsilon$ of both bulk CeO$_2$ and Ce$_2$O$_3$ are derived, which compare
+remarkably well with the available experimental data. These results stress the
+importance of appropriately accounting for local field effects to model the
+dielectric function of metal oxides. Furthermore, we reckon the materials
+energy loss functions $\mbox{Im} (-1/\bar{\epsilon})$, including the accurate
+evaluation of the momentum transfer dispersion from first-principles. In this
+respect, by using a Mermin-type parametrization we are able to model the
+contribution of different electronic excitations to the dielectric loss
+function. Finally, from the knowledge of the electron inelastic mean free path,
+together with the elastic mean free path provided by the relativistic Mott
+theory, we carry out statistical Monte Carlo (MC) charge transport simulations
+to reproduce the major features of the reported experimental reflection
+electron energy loss (REEL) spectra of cerium oxides. The good agreement with
+REEL experimental data strongly supports our approach based on MC modelling
+informed by ab initio calculated electronic excitation spectra in a broad range
+of momentum and energy transfers.",2104.12242v1
+2021-09-02,Drastically enhanced cation incorporation in the epitaxy of oxides due to formation and evaporation of suboxides from elemental sources,"In the molecular beam epitaxy of oxide films, the cation (Sn, Ga) or dopant
+(Sn) incorporation does not follow the vapor pressure of the elemental metal
+sources, but is enhanced by several orders of magnitude for low source
+temperatures. Using line-of-sight quadrupole mass spectrometry, we identify the
+dominant contribution to the total flux emanating from Sn and Ga sources at
+these temperatures to be due to the unintentional formation and evaporation of
+the respective suboxides SnO and Ga$_{2}$O. We quantitatively describe this
+phenomenon by a rate-equation model that takes into account the O background
+pressure, the resulting formation of the suboxides via oxidation of the metal
+source, and their subsequent thermally activated evaporation. As a result, the
+total flux composed of the metal and the suboxide fluxes exhibit an
+\textsf{S}-shape temperature dependence instead of the expected linear one in
+an Arrhenius plot, in excellent agreement with the available experimental data.
+Our model reveals that the thermally activated regimes at low and high
+temperatures are almost exclusively due to suboxide and metal evaporation,
+respectively, joined by an intermediate plateau-like regime in which the flux
+is limited by the available amount of O. An important suboxide contribution is
+expected for all elemental sources whose suboxide exhibits a higher vapor
+pressure than the element, such as B, Ga, In, La, Si, Ge, Sn, Sb, Mo, Nb, Ru,
+Ta, V, and W. This contribution can play a decisive role in the molecular beam
+epitaxy of oxides, including multicomponent or complex oxides, from elemental
+sources. Finally, our model predicts suboxide-dominated growth in low-pressure
+chemical vapor deposition of Ga$_{2}$O$_{3}$ and In$_{2}$O$_{3}$.",2109.01195v1
+2022-06-22,Non-trivial topological phases in transition metal rich half-Heusler Oxides,"Topological Insulators with gapless surface states and insulating bulk in
+non-centrosymmetric cubic systems have been extensively explored following the
+discovery of two-dimensional quantum spin hall effect in zincblende HgTe. In
+such systems the negative band inversion strength E$_{BIS}$ ($=$ E$_{\Gamma_6}
+-$ E$_{\Gamma_8} <$ 0) governs the robustness of the non-trivial topological
+states at ambient conditions. Hence, realizing large negative values of
+E$_{BIS}$ has been a guiding motivation of several investigations reported in
+literature. Here, we present a material design approach which can be employed
+to realize large negative values of E$_{BIS}$ in cubic materials such as
+half-Heusler (HH) oxides with 18 valence electron configurations. We explore 27
+HH oxides of the form ABO (A = Li, K, Rb; B = Cu, Ag, Au) in $\alpha$-,
+$\beta$-, and $\gamma$-phase (by placing transition metal atom at different
+Wyckoff positions) for their non-trivial topological phase. Off these three
+phases, we found that, the $\alpha$-phase of nine HH oxides (wherein the
+transition metal atoms occupy 4a Wyckoff positions in the crystal structure) is
+the most promising with non-trivial topological phase which is governed by the
+mass-darwin relativistic effects enhancing E$_{BIS}$. Whereas the other phases
+were found to be either trivial semiconductors or semimetals or metals and most
+of them being dynamically unstable. We focus on RbAuO in $\alpha$-phase with
+E$_{BIS}$ of $-$ 1.29 eV and the effect of strain fields on the topological
+surface states of this compound. We conclude that the $\alpha$-phase of HH
+oxide presented here can be synthesized experimentally for diverse room
+temperature applications in spintronics and nanoelectronics.",2206.10976v2
+2023-04-24,Development of an eReaxFF Force Field for BZY20 Solid Oxide Electrocatalysis,"Electrocatalysis is a catalytic process where the rate of an electrochemical
+reaction occurring at the electrode-electrolyte interface can be controlled by
+varying the electrical potential. Electrocatalysis can be applied to generate
+hydrogen which can be stored for future use in fuel cells for clean
+electricity. The use of solid oxide in electrocatalysis specially in hydrogen
+evolution reaction is promising. However, further improvements are essential in
+order to meet the ever-increasing global energy demand. Improvement of the
+performance of these high energy chemical systems is directly linked to the
+understanding and improving the complex physical and chemical phenomena and
+exchanges that take place at their different interfaces. To enable large length
+and time scale atomistic simulations of solid oxide electrocatalysis for
+hydrogen generation, we developed an eReaxFF force field for barium zirconate
+doped with 20 mol% of yttrium (BZY20). All parameters for the eReaxFF were
+optimized to reproduce quantum mechanical (QM) calculations on relevant
+condensed phase and cluster systems describing oxygen vacancies, vacancy
+migrations, water adsorption, water splitting and hydrogen generation on the
+surfaces of the BZY20 solid oxide. Using the developed force field, we
+performed zero-voltage molecular dynamics simulations to observe water
+adsorption and the eventual hydrogen production. Based on our simulation
+results, we conclude that this force field sets a stage for the introduction of
+explicit electron concept in order to simulate electron conductivity, electron
+leakage and non-zero-voltage effects on hydrogen generation. Overall, we
+demonstrate how atomistic-scale simulations can enhance our understanding of
+processes at interfaces in solid oxide materials.",2304.14256v1
+2023-09-12,Universal interatomic potential for perovskite oxides,"With their celebrated structural and chemical flexibility, perovskite oxides
+have served as a highly adaptable material platform for exploring emergent
+phenomena arising from the interplay between different degrees of freedom.
+Molecular dynamics (MD) simulations leveraging classical force fields, commonly
+depicted as parameterized analytical functions, have made significant
+contributions in elucidating the atomistic dynamics and structural properties
+of crystalline solids including perovskite oxides. However, the force fields
+currently available for solids are rather specific and offer limited
+transferability, making it time-consuming to use MD to study new materials
+systems since a new force field must be parameterized and tested first. The
+lack of a generalized force field applicable to a broad spectrum of solid
+materials hinders the facile deployment of MD in computer-aided materials
+discovery (CAMD). Here, by utilizing a deep-neural network with a
+self-attention scheme, we have developed a unified force field that enables MD
+simulations of perovskite oxides involving 14 metal elements and conceivably
+their solid solutions with arbitrary compositions. Notably, isobaric-isothermal
+ensemble MD simulations with this model potential accurately predict the
+experimental phase transition sequences for several markedly different
+ferroelectric oxides, including a 6-element ternary solid solution,
+Pb(In$_{1/2}$Nb$_{1/2}$)O$_3$--Pb(Mg$_{1/3}$Nb$_{2/3}$)O$_3$--PbTiO$_3$. We
+believe the universal interatomic potential along with the training database,
+proposed regression tests, and the auto-testing workflow, all released
+publicly, will pave the way for a systematic improvement and extension of a
+unified force field for solids, potentially heralding a new era in CAMD.",2309.06391v3
+2023-10-19,Limits of dispersoid size and number density in oxide dispersion strengthened alloys fabricated with powder bed fusion-laser beam,"Previous work on additively-manufactured oxide dispersion strengthened alloys
+focused on experimental approaches, resulting in larger dispersoid sizes and
+lower number densities than can be achieved with conventional powder
+metallurgy. To improve the as-fabricated microstructure, this work integrates
+experiments with a thermodynamic and kinetic modeling framework to probe the
+limits of the dispersoid sizes and number densities that can be achieved with
+powder bed fusion-laser beam. Bulk samples of a Ni-20Cr $+$ 1 wt.% Y$_2$O$_3$
+alloy are fabricated using a range of laser power and scanning velocity
+combinations. Scanning transmission electron microscopy characterization is
+performed to quantify the dispersoid size distributions across the processing
+space. The smallest mean dispersoid diameter (29 nm) is observed at 300 W and
+1200 mm/s, with a number density of 1.0$\times$10$^{20}$ m$^{-3}$. The largest
+mean diameter (72 nm) is observed at 200 W and 200 mm/s, with a number density
+of 1.5$\times$10$^{19}$ m$^{-3}$. Scanning electron microscopy suggests that a
+considerable fraction of the oxide added to the feedstock is lost during
+processing, due to oxide agglomeration and the ejection of oxide-rich spatter
+from the melt pool. After accounting for these losses, the model predictions
+for the dispersoid diameter and number density align with the experimental
+trends. The results suggest that the mechanism that limits the final number
+density is collision coarsening of dispersoids in the melt pool. The modeling
+framework is leveraged to propose processing strategies to limit dispersoid
+size and increase number density.",2310.12416v3
+2024-03-26,"Utilizing (Al, Ga)2O3/Ga2O3 superlattices to measure cation vacancy diffusion and vacancy-concentration-dependent diffusion of Al, Sn, and Fe in \b{eta} -Ga2O3","Diffusion of native defects such as vacancies and their interactions with
+impurities are fundamental in semiconductor crystal growth, device processing,
+and long-term aging of equilibration and transient diffusion of vacancies are
+rarely investigated. We used aluminum-gallium oxide/gallium oxide superlattices
+(SLs) to detect and analyze transient diffusion of cation vacancies during
+annealing in O2 at 1000-1100 C. Using a novel finite difference scheme for the
+diffusion equation with time- and space-varying diffusion constant, we extract
+diffusion constants for Al, Fe, and cation vacancies under the given
+conditions, including the vacancy concentration dependence for Al. indicate
+that vacancies present in the substrate transiently diffuse through the SLs,
+interacting with Sn as it also diffuses. In the case of SLs grown on Sn-doped
+beta-gallium oxide substrates, gradients observed in the extent of Al diffusion
+indicate that vacancies present in the substrate transiently diffuse through
+the SLs, interacting with Sn as it also diffuses. In the case of SLs grown on
+(010) Fe-doped substrates, the Al diffusion is uniform through the SLs,
+indicating a depth-uniform concentration of vacancies. We find no evidence in
+either case for the introduction of gallium vacancies from the free surface at
+rates sufficient to affect Al diffusion down to ppm concentrations, which has
+important bearing on the validity of typically-made assumptions of vacancy
+equilibration. Additionally, we show that unintentional impurities in Sn-doped
+gallium oxide such as Fe, Ni, Mn, Cu, and Li also diffuse towards the surface
+and accumulate. Many of these likely have fast interstitial diffusion modes
+capable of destabilizing devices over time, thus highlighting the importance of
+controlling unintentional impurities in beta-gallium oxide wafers.",2403.17298v1
+2024-03-27,Classical dynamics and semiclassical analysis of excitons in cuprous oxide,"Excitons, as bound states of electrons and holes, embody the solid state
+analogue of the hydrogen atom, whose quantum spectrum is explained within a
+classical framework by the Bohr-Sommerfeld atomic model. In a first
+hydrogenlike approximation the spectra of excitons are also well described by a
+Rydberg series, however, due to the surrounding crystal environment deviations
+from this series can be observed. A theoretical treatment of excitons in
+cuprous oxide needs to include the band structure of the crystal, leading to a
+prominent fine-structure splitting in the quantum spectra. This is achieved by
+introducing additional spin degrees of freedom into the system, making the
+existence and meaningfulness of classical exciton orbits in the physical system
+a non-trivial question. Recently, we have uncovered the contributions of
+periodic exciton orbits directly in the quantum mechanical recurrence spectra
+of cuprous oxide [J. Ertl et al., Phys. Rev. Lett. 129, 067401 (2022)] by
+application of a scaling technique and fixing the energy of the classical
+dynamics to a value corresponding to a principle quantum number $n=5$ in the
+hydrogenlike case. Here, we present a comprehensive derivation of the classical
+and semiclassical theory of excitons in cuprous oxide. In particular, we
+investigate the energy dependence of the exciton dynamics. Both the
+semiclassical and quantum mechanical recurrence spectra exhibit stronger
+deviations from the hydrogenlike behavior with decreasing energy, which is
+related to a growing influence of the spin-orbit coupling and thus a higher
+velocity of the secular motion of the exciton orbits. The excellent agreement
+between semiclassical and quantum mechanical exciton recurrence spectra
+demonstrates the validity of the classical and semiclassical approach to
+excitons in cuprous oxide.",2403.18303v1
+2023-04-26,Systematic Improvements in Transmon Qubit Coherence Enabled by Niobium Surface Encapsulation,"We present a novel transmon qubit fabrication technique that yields
+systematic improvements in T$_1$ relaxation times. We fabricate devices using
+an encapsulation strategy that involves passivating the surface of niobium and
+thereby preventing the formation of its lossy surface oxide. By maintaining the
+same superconducting metal and only varying the surface structure, this
+comparative investigation examining different capping materials, such as
+tantalum, aluminum, titanium nitride, and gold, and film substrates across
+different qubit foundries definitively demonstrates the detrimental impact that
+niobium oxides have on the coherence times of superconducting qubits, compared
+to native oxides of tantalum, aluminum or titanium nitride. Our
+surface-encapsulated niobium qubit devices exhibit T$_1$ relaxation times 2 to
+5 times longer than baseline niobium qubit devices with native niobium oxides.
+When capping niobium with tantalum, we obtain median qubit lifetimes above 300
+microseconds, with maximum values up to 600 microseconds, that represent the
+highest lifetimes to date for superconducting qubits prepared on both sapphire
+and silicon. Our comparative structural and chemical analysis suggests why
+amorphous niobium oxides may induce higher losses compared to other amorphous
+oxides. These results are in line with high-accuracy measurements of the
+niobium oxide loss tangent obtained with ultra-high Q superconducting
+radiofrequency (SRF) cavities. This new surface encapsulation strategy enables
+even further reduction of dielectric losses via passivation with ambient-stable
+materials, while preserving fabrication and scalable manufacturability thanks
+to the compatibility with silicon processes.",2304.13257v3
+2022-09-09,Magnetically confined mountains on accreting neutron stars with multipole magnetic fields,"Magnetically confined mountains on accreting neutron stars are candidates for
+producing continuous gravitational waves. We formulate a magnetically confined
+mountain on a neutron star with strong multipole magnetic fields and obtain
+some sequences of numerical solutions. We find that the mass ellipticity of the
+mountain increases by one order of magnitude if the neutron star has strong
+multipole magnetic fields. As matter accretes on to the magnetic pole, the size
+of the mountain increases and the magnetic fields are buried. If the neutron
+star has a dipole magnetic field, the dipole magnetic field is buried and
+transformed into multipole components. By contrast, if the neutron star has
+both dipole and strong multipole magnetic fields, the multipole magnetic fields
+are buried and transformed into a negative dipole component. We also calculate
+magnetically confined mountains with toroidal magnetic fields and find that the
+ellipticity becomes slightly smaller when the mountain has toroidal magnetic
+fields. If the multipole magnetic fields are buried, they sustain the intense
+toroidal magnetic field near the stellar surface, and the ratio of the toroidal
+magnetic field to the poloidal magnetic field is close to 100. The hidden
+strong toroidal magnetic fields are sustained by the buried multipole magnetic
+fields.",2209.04352v1
+2022-10-31,Superconducting Magnet System Concept with a Mechanical Energy Transfer in the Magnetic Field,"There is an interest to design superconducting magnet systems working in a
+persistent current mode. These systems continuously generate magnetic field
+with disconnected power source working like permanent magnet devices. In this
+paper proposed a magnet system concept based on the direct mechanical energy
+transfer in the magnetic field. Short circuited superconducting coils do not
+have current leads and power source. To pump the mechanical energy in the
+superconducting coil used a magnetizer which magnetically coupled with the
+coil. The mechanical removing the magnetizer from the magnet induces a
+persistent current in the superconducting coil which generates the magnetic
+field. Iron dominated magnet system concept was investigated using OPERA3d code
+which confirmed a visibility of proposed approach.",2211.00102v1
+2014-06-25,Transforming magnets,"Based on the form-invariant of Maxwell's equations under coordinate
+transformations, we extend the theory of transformation optics to
+transformation magneto-statics, which can design magnets through coordinate
+transformations. Some novel DC magnetic field illusions created by magnets
+(e.g. shirking magnets, cancelling magnets and overlapping magnets) are
+designed and verified by numerical simulations. Our research will open a new
+door to designing magnets and controlling DC magnetic fields.",1406.6512v1
+2019-02-26,The Evidence of Cathodic Micro-discharges during Plasma Electrolytic Oxidation Process,"Plasma electrolytic oxidation (PEO) processing of EV 31 magnesium alloy has
+been carried out in fluoride containing electrolyte under bipolar pulse current
+regime. Unusual PEO cathodic micro-discharges have been observed and
+investigated. It is shown that the cathodic micro-discharges exhibit a
+collective intermittent behavior which is discussed in terms of charge
+accumulations at the layer/electrolyte and layer/metal interfaces. Optical
+emission spectroscopy is used to determine the electron density (typ. 10 15
+cm-3) and the electron temperature (typ. 7500 K) while the role of F-anions on
+the appearance of cathodic micro-discharges is pointed out. Plasma Electrolytic
+Oxidation (PEO) is a promising plasma-assisted surface treatment of light
+metallic alloys (e.g. Al, Mg, Ti). Although the PEO process makes it possible
+to grow oxide coatings with interesting corrosion and wear resistant
+properties, the physical mechanisms of coating growth are not yet completely
+understood. Typically, the process consists in applying a high voltage
+difference between a metallic piece and a counter-electrode which are both
+immersed in an electrolyte bath. Compare to anodizing, the main differences
+concern the electrolyte composition and the current and voltage ranges which
+are at least one order of magnitude higher in PEO 1. These significant
+differences in current and voltage imply the dielectric breakdown and
+consequently the appearance of micro-discharges on the surface of the sample
+under processing. Those micro-discharges are recognized as being the main
+contributors to the formation of a dielectric porous crystalline oxide coating.
+2 Nevertheless, the breakdown mechanism that governs the appearance of those
+micro-discharges is still under investigation. Hussein et al. 3 proposed a
+mechanism with three different plasma formation processes based on differences
+in plasma chemical composition. The results of Jovovi{\'c} et al. 4,5
+concerning physical properties of the plasma seem to corroborate this
+mechanism, and also point out the importance of the substrate material in the
+plasma composition. 6 Compared with DC conducted PEO process, using a bipolar
+pulsed DC or AC current supply gives supplementary control latitude through the
+current waveform parameters. The effect of these parameter on the
+micro-discharges behavior has been investigated in several previous works.
+2,3,7,8 One of the main results of these studies is the absence of
+micro-discharge during the cathodic current half-period. 9-11 Even if the
+cathodic half-period has an obvious effect on the efficiency of PEO as well as
+on the coating growth and composition, the micro-plasmas appear only in anodic
+half-period. Sah et al. 8 have observed the cathodic breakdown of an oxide
+layer but at very high current density (10 kA.dm-${}^2$), and after several
+steps of sample preparation. Several models of micro-discharges appearance in
+AC current have already been proposed. 1,2,8,12,13 Though cathodic
+micro-discharges have never been observed within usual process conditions, the
+present study aims at defining suitable conditions to promote cathodic
+micro-discharges and at studying the main characteristics of these
+micro-plasmas.",1902.09828v1
+2016-09-27,The magnetic properties of the hollow cylindrical ideal remanence magnet,"We consider the magnetic properties of the hollow cylindrical ideal remanence
+magnet. This magnet is the cylindrical permanent magnet that generates a
+uniform field in the cylinder bore, using the least amount of magnetic energy
+to do so. The remanence distribution of this magnet is derived and the
+generated field is compared to that of a Halbach cylinder of equal dimensions.
+The ideal remanence magnet is shown in most cases to generate a significantly
+lower field than the equivalent Halbach cylinder, although the field is
+generated with higher efficiency. The most efficient Halbach cylinder is shown
+to generate a field exactly twice as large as the equivalent ideal remanence
+magnet.",1609.08548v1
+2022-07-19,Magnetic Field of a Permanent Magnet,"For magnetic field calculations, cylindrical permanent magnets are often
+approximated as ideal, azimuthally symmetric solenoids. Despite the frequent
+usage of this approximation, research papers demonstrating the validity and
+limitations of this approach are scarcely available. In this paper, the
+experimentally derived magnetic field of a cylindrical permanent magnet is
+compared with the analytically calculated magnetic field of an ideal solenoid.
+An experimental setup for measuring the magnetic field distribution is
+demonstrated and employed for gathering the data. The proposed setup allows to
+measure the distributions of the axial and radial components of the magnetic
+field surrounding the magnet. The experimental data is in a very good agreement
+with the theoretical predictions, confirming the validity of using the model of
+an ideal solenoid for predicting a magnetic field distribution of a permanent
+magnet.",2207.09911v1
+2022-09-09,Magnetization dynamics and reversal of two-dimensional magnets,"Micromagnetics simulation based on the classical Landau-Lifshitz-Gilbert
+(LLG) equation has long been a powerful method for modeling magnetization
+dynamics and reversal of three-dimensional (3D) magnets. For two-dimensional
+(2D) magnets, the magnetization reversal always accompanies the collapse of the
+magnetization even at low temperatures due to intrinsic strong spin
+fluctuation. We propose a micromagnetic theory that explicitly takes into
+account the rapid demagnetization and remagnetization dynamics of 2D magnets
+during magnetization reversal. We apply the theory to a single-domain magnet to
+illustrate fundamental differences in magnetization trajectories and reversal
+times for 2D and 3D magnets.",2209.04483v1
+2004-08-24,Reconsidering the origin of the 21 micron feature: Oxides in carbon-rich PPNe?,"The origin of the so-called ""21 micron"" feature which is especially prominent
+in the spectra of some carbon-rich protoplanetary nebulae (PPNe}) is the matter
+of a lively debate. A large number of potential band carriers have been
+presented and discarded within the past decade. The present paper gives an
+overview of the problems related to the hitherto proposed feature
+identifications, including the recently suggested candidate carrier silicon
+carbide. We also discuss the case for spectroscopically promising oxides.
+  SiC is shown to produce a strong resonance band at 20-21 micron if coated by
+a layer of silicon dioxide. At low temperatures, core-mantle particles composed
+of SiC and amorphous SiO$_2$ indeed have their strongest spectral signature at
+a position of 20.1 micron, which coincides with the position of the ""21 micron""
+emission band.
+  The optical constants of another candidate carrier that has been relatively
+neglected so far -- iron monoxide -- are proven to permit a fairly accurate
+reproduction of the ""21 micron"" feature profile as well, especially when
+low-temperature measurements of the infrared properties of FeO are taken into
+account. As candidate carrier of the ""21 micron"" emission band, FeO has the
+advantage of being stable against further oxidation and reduction only in a
+narrow range of chemical and physical conditions, coinciding with the fact that
+the feature, too, is detected in a small group of objects only. However, it is
+unclear how FeO should form or survive particularly in carbon-rich PPNe.",0408447v1
+1999-07-22,Coupling strength of charge carriers to spin fluctuations in high-temperature superconductors,"In conventional superconductors, the most direct evidence of the mechanism
+responsible for superconductivity comes from tunneling experiments in which a
+clear image of the electron-phonon interaction is revealed. The observed
+structure in the current voltage characteristics at the phonon energies can be
+used to measure, through inversion of the Eliashberg equations, the electron
+phonon spectral density \alpha^2F(\omega). The coherence length in conventional
+materials is long and the tunneling process probes several atomic layers into
+the bulk of the superconductor. On the contrary, in the high-T_c oxides,
+particularly for c-axis tunneling, the coherence length can be quite short and
+in an optical experiment or in neutron scattering experiments the bulk of the
+sample is probed. Therefore, these spectroscopies become the methods of choice
+for the investigation of mechanisms of high-T_c superconductivity. Accurate
+reflectance measurements in the infrared range and precise polarized neutron
+scattering data are available for a variety of oxides. In this paper we show
+that conducting carriers studied by means of infrared spectroscopy reveal
+strong coupling to a resonance structure in the spectrum of spin fluctuations
+examined with neutron scattering. The coupling strength inferred from
+experiment is sufficient to account for high values of T_c which signals the
+prominent role of spin excitations in the superconductivity of oxides.",9907338v2
+1999-08-17,Experiments on Ladders Reveal a Complex Interplay between a Spin-Gapped Normal State and Superconductivity,"In recent years, the study of ladder materials has developed into a
+well-established area of research within the general context of Strongly
+Correlated Electrons. This effort has been triggered by an unusual
+cross-fertilization between theory and experiments. In this paper, the main
+experimental results obtained in the context of ladders are reviewed from the
+perspective of a theorist. Emphasis is given to the many similarities between
+the two-dimensional high-$\rm T_c$ cuprates and the two-leg ladder compounds,
+including Sr$_{14-x}$Ca$_x$Cu$_{24}$O$_{41}$ (14-24-41) which has a
+superconducting phase at high pressure and a small hole density. Examples of
+these similarities include regimes of linear resistivity vs temperature in
+metallic ladders and a normal state with spin-gap or pseudogap characteristics.
+Some controversial results in this context are also discussed. It is remarked
+that the ladder 14-24-41 is the first superconducting copper-oxide material
+with a non-square-lattice layered arrangement, and certainly much can be
+learned from a careful analysis of this compound. A short summary of the main
+theoretical developments in this field is also included, as well as a brief
+description of the properties of non-copper-oxide ladders. Suggestions by the
+author on possible experiments are described in the text. Overall, it is
+concluded that the enormous experimental effort carried out on ladders has
+already unveiled quite challenging and interesting physics that adds to the
+rich behavior of electrons in transition-metal-oxides, and in addition
+contributes to the understanding of the two-dimensional cuprates. However,
+still considerable work needs to be carried out to fully understand the
+interplay between charge and spin degrees of freedom in these materials.",9908250v1
+2004-04-13,Electron Phonon Interaction and Strong Correlations in High-Temperature Superconductors: One can not avoid unavoidable,"The important role of the electron-phonon interaction (EPI) in explaining the
+properties of the normal state and pairing mechanism in high-T$_{c}$
+superconductors (HTSC) is discussed. A number of experimental results are
+analyzed such as: dynamical conductivity, Raman scattering, neutron scattering,
+ARPES, tunnelling measurements, isotope effect and etc. They give convincing
+evidence that the EPI is strong and dominantly contributes to pairing in HTSC
+oxides. It is argued that strong electronic correlations in conjunction with
+the pronounced (in relatively weakly screened materials) EPI are unavoidable
+ingredients for the microscopic theory of pairing in HTSC oxides. I present the
+well defined and controllable theory of strong correlations and the EPI. It is
+shown that strong correlations give rise to the pronounced \textit{forward
+scattering peak} in the EPI - the FSP theory. The FSP theory explains in a
+consistent way several (crucial) puzzles such as much smaller transport
+coupling constant than the pairing one ($\lambda_{tr}\ll \lambda$), which are
+present if one interprets the results in HTSC oxides by the old
+Migdal-Eliashberg theory for the EPI. The ARPES shift puzzle where the nodal
+kink at 70 meV is unshifted in the superconducting state, while the anti-nodal
+one at 40 meV is shifted can be explained at present only by the FSP theory. A
+number of other interesting predictions of the FSP theory are also discussed.",0404287v1
+2005-07-29,Charge states of strongly correlated 3d oxides: from typical insulator to unconventional electron-hole Bose liquid,"We develop a model approach to describe charge fluctuations and different
+charge phases in strongly correlated 3d oxides. As a generic model system one
+considers that of centers each with three possible valence states described in
+frames of pseudo-spin (isospin) formalism by an effective anisotropic
+non-Heisenberg Hamiltonian. Simple uniform mean-field phases include an
+insulating monovalent phase, mixed-valence binary disproportionated phase, and
+mixed-valence ternary under-disproportionated phase. We consider two first
+phases in more details focusing on the problem of electron/hole states and
+different types of excitons in monovalent phase and formation of electron-hole
+Bose liquid in disproportionated phase. Pseudo-spin formalism provides a useful
+framework for revealing and describing different topological charge
+fluctuations, in particular, like domain walls or bubble domains in
+antiferromagnets. All the insulating systems such as monovalent phase may be
+subdivided to two classes: stable and unstable ones with regard to the
+formation of self-trapped charge transfer (CT) excitons. The latter systems
+appear to be unstable with regard to the formation of CT exciton clusters, or
+droplets of the electron-hole Bose liquid. The model approach suggested is
+believed to be applied to describe a physics of strongly correlated oxides with
+charge transfer excitonic instability and a mixed valence. We shortly discuss
+an unconventional scenario of the essential physics of cuprates and manganites
+that implies their instability with regard to the self-trapping of charge
+transfer excitons and the formation of electron-hole Bose liquid.",0507705v1
+2008-03-20,Electronic charge and orbital reconstruction at cuprate-titanate interfaces,"In complex transition metal oxide heterostructures of physically dissimilar
+perovskite compounds, interface phenomena can lead to novel physical properties
+not observed in either of their constituents. This remarkable feature opens new
+prospects for technological applications in oxide electronic devices based on
+nm-thin oxide films. Here we report on a significant electronic charge and
+orbital reconstruction at interfaces between YBa2Cu3O6 and SrTiO3 studied using
+local spin density approximation (LSDA) with intra-atomic Coulomb repulsion
+(LSDA+U). We show that the interface polarity results in the metallicity of
+cuprate-titanate superlattices with the hole carriers concentrated
+predominantly in the CuO2 and BaO layers and in the first interface TiO2 and
+SrO planes. We also find that the interface structural relaxation causes a
+strong change of orbital occupation of Cu 3d orbitals in the CuO2 layers. The
+concomitant change of Cu valency from +2 to +3 is related to the partial
+occupation of the Cu $3d_{3z^2-r^2}$ orbitals at the interface with SrO planes
+terminating SrTiO3. Interface-induced predoping and orbital reconstruction in
+CuO2 layers are key mechanisms which control the superconducting properties of
+field-effect devices developed on the basis of cuprate-titanate
+heterostructures.",0803.2988v1
+2008-09-11,Experimental and modeling study of the low-temperature oxidation of large alkanes,"This paper presents an experimental and modeling study of the oxidation of
+large linear akanes (from C10) representative from diesel fuel from low to
+intermediate temperature (550-1100 K) including the negative temperature
+coefficient (NTC) zone. The experimental study has been performed in a
+jet-stirred reactor at atmospheric pressure for n-decane and a
+n-decane/n-hexadecane blend. Detailed kinetic mechanisms have been developed
+using computer-aided generation (EXGAS) with improved rules for writing
+reactions of primary products. These mechanisms have allowed a correct
+simulation of the experimental results obtained. Data from the literature for
+the oxidation of n-decane, in a jet-stirred reactor at 10 bar and in shock
+tubes, and of n-dodecane in a pressurized flow reactor have also been correctly
+modeled. A considerable improvement of the prediction of the formation of
+products is obtained compared to our previous models. Flow rates and
+sensitivity analyses have been performed in order to better understand the
+influence of reactions of primary products. A modeling comparison between
+linear alkanes for C8 to C16 in terms of ignition delay times and the formation
+of light products is also discussed.",0809.1921v1
+2009-05-28,Mottness in High-Temperature Copper-Oxide Superconductors,"The standard theory of metals, Fermi liquid theory, hinges on the key
+assumption that although the electrons interact, the low-energy excitation
+spectrum stands in a one-to-one correspondence with that of a non-interacting
+system. In the normal state of the copper-oxide high-temperature
+superconductors, drastic deviations from the Fermi liquid picture obtain,
+highlighted by a pseudogap, broad spectral features and $T-$ linear
+resistivity. This article focuses on the series of experiments on the
+copper-oxide superconductors which reveal that the number of low-energy
+addition states per electron per spin exceeds unity, in direct violation of the
+key Fermi liquid tenet. These experiments point to new degrees of freedom, not
+made out of the elemental excitations, as the key mechanism by which Fermi
+liquid theory breaks down in the cuprates. A recent theoretical advance which
+permits an explicit integration of the high energy scale in the standard model
+for the cuprates reveals the source of the new dynamical degrees of freedom at
+low energies, a charge 2e bosonic field which has nothing to do with pairing
+but rather represents the mixing with the high energy scales. We demonstrate
+explicitly that at half-filling, this new degree of freedom provides a
+dynamical mechanism for the generation of the charge gap, antiferromagnetism in
+the insulating phase and explains many of the anomalies in the normal state of
+the cuprates.",0905.4637v1
+2009-06-19,Enhancement mode double top gated MOS nanostructures with tunable lateral geometry,"We present measurements of silicon (Si) metal-oxide-semiconductor (MOS)
+nanostructures that are fabricated using a process that facilitates essentially
+arbitrary gate geometries. Stable Coulomb blockade behavior free from the
+effects of parasitic dot formation is exhibited in several MOS quantum dots
+with an open lateral quantum dot geometry. Decreases in mobility and increases
+in charge defect densities (i.e. interface traps and fixed oxide charge) are
+measured for critical process steps, and we correlate low disorder behavior
+with a quantitative defect density. This work provides quantitative guidance
+that has not been previously established about defect densities for which Si
+quantum dots do not exhibit parasitic dot formation. These devices make use of
+a double-layer gate stack in which many regions, including the critical gate
+oxide, were fabricated in a fully-qualified CMOS facility.",0906.3748v2
+2010-03-03,Effects of Mismatch Strain and Substrate Surface Corrugation on Morphology of Supported Monolayer Graphene,"Graphene monolayers supported on oxide substrates have been demonstrated with
+superior charge mobility and thermal transport for potential device
+applications. Morphological corrugation can strongly influence the transport
+properties of the supported graphene. In this paper, we theoretically analyze
+the morphological stability of a graphene monolayer on an oxide substrate,
+subject to van der Waals interactions and in-plane mismatch strains. First, we
+define the equilibrium separation and the interfacial adhesion energy as the
+two key parameters that characterize the van der Waals interaction between a
+flat monolayer and a flat substrate surface. By a perturbation analysis, a
+critical compressive mismatch strain is predicted, beyond which the graphene
+monolayer undergoes strain-induced instability, forming corrugations with
+increasing amplitude and decreasing wavelength on a perfectly flat surface.
+When the substrate surface is not perfectly flat, the morphology of graphene
+depends on both the amplitude and the wavelength of the surface corrugation. A
+transition from conformal (corrugated) to non-conformal (flat) morphology is
+predicted. The effects of substrate surface corrugation on the equilibrium mean
+thickness of the supported graphene and the interfacial adhesion energy are
+analyzed. Furthermore, by considering both the substrate surface corrugation
+and the mismatch strain, it is found that, while a tensile mismatch strain
+reduces the corrugation amplitude of graphene, a corrugated substrate surface
+promotes strain-induced instability under a compressive strain. These
+theoretical results suggest possible means to control the morphology of
+graphene monolayer on oxide substrates by surface patterning and strain
+engineering.",1003.0853v1
+2010-09-17,Unveiling a two-dimensional electron gas with universal subbands at the surface of SrTiO3,"Similar to silicon that is the basis of conventional electronics, strontium
+titanate (SrTiO3) is the bedrock of the emerging field of oxide electronics.
+SrTiO3 is the preferred template to create exotic two-dimensional (2D) phases
+of electron matter at oxide interfaces, exhibiting metal-insulator transitions,
+superconductivity, or large negative magnetoresistance. However, the physical
+nature of the electronic structure underlying these 2D electron gases (2DEGs)
+remains elusive, although its determination is crucial to understand their
+remarkable properties. Here we show, using angle-resolved photoemission
+spectroscopy (ARPES), that there is a highly metallic universal 2DEG at the
+vacuum-cleaved surface of SrTiO3, independent of bulk carrier densities over
+more than seven decades, including the undoped insulating material. This 2DEG
+is confined within a region of ~5 unit cells with a sheet carrier density of
+~0.35 electrons per a^2 (a is the cubic lattice parameter). We unveil a
+remarkable electronic structure consisting on multiple subbands of heavy and
+light electrons. The similarity of this 2DEG with those reported in
+SrTiO3-based heterostructures and field-effect transistors suggests that
+different forms of electron confinement at the surface of SrTiO3 lead to
+essentially the same 2DEG. Our discovery provides a model system for the study
+of the electronic structure of 2DEGs in SrTiO3-based devices, and a novel route
+to generate 2DEGs at surfaces of transition-metal oxides.",1009.3412v1
+2010-10-05,Creation and control of a two-dimensional electron liquid at the bare SrTiO3 surface,"Many-body interactions in transition-metal oxides give rise to a wide range
+of functional properties, such as high-temperature superconductivity, colossal
+magnetoresistance, or multiferroicity. The seminal recent discovery of a
+two-dimensional electron gas (2DEG) at the interface of the insulating oxides
+LaAlO3 and SrTiO3 represents an important milestone towards exploiting such
+properties in all-oxide devices. This conducting interface shows a number of
+appealing properties, including a high electron mobility, superconductivity,
+and large magnetoresistance and can be patterned on the few-nanometer length
+scale. However, the microscopic origin of the interface 2DEG is poorly
+understood. Here, we show that a similar 2DEG, with an electron density as
+large as 8x10^13 cm^-2, can be formed at the bare SrTiO3 surface. Furthermore,
+we find that the 2DEG density can be controlled through exposure of the surface
+to intense ultraviolet (UV) light. Subsequent angle-resolved photoemission
+spectroscopy (ARPES) measurements reveal an unusual coexistence of a light
+quasiparticle mass and signatures of strong many-body interactions.",1010.0763v2
+2010-11-07,Interactions between sub-10 nm iron and cerium oxide nanoparticles and 3T3 fibroblasts : the role of the coating and aggregation state,"Recent nanotoxicity studies revealed that the physico-chemical
+characteristics of engineered nanomaterials play an important role in the
+interactions with living cells. Here, we report on the toxicity and uptake of
+the cerium and iron oxide sub-10 nm nanoparticles by NIH/3T3 mouse fibroblasts.
+Coating strategies include low-molecular weight ligands (citric acid) and
+polymers (poly(acrylic acid), MW = 2000 g mol-1). Electrostatically adsorbed on
+the surfaces, the organic moieties provide a negatively charged coating in
+physiological conditions. We find that most particles were biocompatible, as
+exposed cells remained 100% viable relative to controls. Only the bare and the
+citrate-coated nanoceria exhibit a slight decrease of the mitochondrial
+activity for cerium concentrations above 5 mM (equivalent to 0.8 g L-1). We
+also observe that the citrate-coated particles are internalized by the cells in
+large amounts, typically 250 pg per cell after a 24 h incubation for iron
+oxide. In contrast, the polymer-coated particles are taken up at much lower
+rates (< 30 pg per cell). The strong uptake shown by the citrate-coated
+particles is related to the destabilization of the dispersions in the cell
+culture medium and their sedimentation down to the cell membranes. In
+conclusion, we show that the uptake of nanomaterials by living cells depends on
+the coating of the particles and on its ability to preserve the colloidal
+nature of the dispersions.",1011.1670v1
+2010-12-29,Competing Exotic Topological Insulator Phases in Transition Metal Oxides on the Pyrochlore Lattice with Distortion,"In this work we investigate the phase diagram of heavy (4d and 5d) transition
+metal oxides on the pyrochlore lattice, such as those of the form
+$\mathrm{A_2M_2O_7}$, where A is a rare earth element and M is a transition
+metal element. We focus on the competition between Coulomb interaction,
+spin-orbit coupling, and lattice distortion when these energy scales are
+comparable. Strong spin-orbit coupling entangles the spin and the $t_{2g}$
+$d$-orbitals giving rise to doublet $j=1/2$ and quadruplet $j=3/2$ states. In
+contrast to previous works which focused on the doublet manifold, we also
+discuss the quadruplet manifold which is relevant for several pyrochlore
+oxides. The Coulomb interaction is taken into account by use of the slave-rotor
+mean field theory and different classes of lattice distortions which further
+split the levels of the quadruplet $j=3/2$ manifold are studied. Various
+topological phases are predicted, including exotic strong and weak topological
+Mott insulating phases. We discuss the general structure of the phase diagram
+for several values of $d$-shell filling and various symmetry classes of lattice
+distortions. Our results are relevant to the search for exotic topological
+insulators and quantum spin liquids in strongly correlated materials with
+strong spin-orbit coupling.",1101.0007v2
+2011-02-06,Enhanced Li capacity at high lithiation potentials in graphene oxide,"We have studied lithiation of graphene oxide (GO) as a function of oxygen
+coverage using first principles calculations. Our results show that the
+lithiation potentials and capacities in GO can be tuned by controlling the
+oxygen coverage, or the degree of reduction. We find a range of coverages where
+the lithiation potentials are above the solid electrolyte interface (SEI)
+formation threshold, but with capacities comparable to, or larger than
+graphite. We observe that in highly oxidized and mildly reduced sheets,
+lithiation occurs through the formation of Li-O bonds, whereas at low coverages
+that are typical of reduced-GO (rGO) (O:C - 12.5 %), both Li-O bonds and LiC6
+configurations are observed. The covalent Li-O bond is much stronger than the
+bonds formed in the LiC6 ring and the lithiation potentials for epoxides at
+high and medium coverages are generally large (> 1 eV). For these
+congifurations, as in the case of Li4Ti5O12 anodes, there will be no formation
+of SEI, but with the additional advantage of having higher lithium storage
+capacity than Li4Ti5O12. In reduced GO sheets, the presence of residual oxygen
+atoms allows for formation of covalent Li-O bonds that lead to storage
+capacities and lithiation potentials higher than that of graphite. Finally, our
+calculations show high lithiation potentials for the edges of graphene
+nanoribbons, which will impede the formation of SEI and hence lead to large
+reversible capacity.",1102.1211v1
+2011-06-06,An electron hole doping and soft x-ray spectroscopy study on La1-xSrxFe0.75Ni0.25O3-δ,"The conductivity of the electron hole and polaron conductor
+La1-xSrxFe0.75Ni0.25O3-{\delta}, a potential cathode material for intermediate
+temperature solid oxide fuel cells, was studied for 0 <x < 1 and for
+temperatures 300 K <T < 1250 K. In LaSrFe-oxide, an ABO3 type perovskite,
+A-site substitu-tion of the trivalent La3+ by the divalent Sr2+ causes
+oxidation of Fe3+ towards Fe4+, which forms conducting electron holes. Here we
+have in addition a B-site substitution by Ni. The compound for x = 0.5 is
+identified as the one with the highest conductivity ({\sigma} ~ 678 S/cm) and
+lowest activation energy for polaron conductivity (Ep = 39 meV). The evolution
+of the electronic structure was monitored by soft x-ray Fe and oxygen K-edge
+spectroscopy. Homogeneous trend for the oxida-tion state of the Fe was
+observed. The variation of the ambient temperature conductivity and activation
+energy with relative Sr content (x) shows a correlation with the ratio of
+(eg/eg+t2g) in Fe L3 edge up to x=0.5. The hole doping process is reflected by
+an almost linear trend by the variation of the pre-peaks of the oxygen K-edge
+soft x-ray absorption spectra.",1106.1019v1
+2011-07-30,"Synthesis, Structural, Electrical and Microchemistry Properties of Novel (LSCFM) LaxSr1-xCo1-y-zFeyMnzO3-δ (x=0.4, 0.6, 0.8, y=0.4, 0.8 and z=0.1, 0.2) Perovskites for SOFC Applications","Perovskites are mixed oxides with the general formula ABO3. Many different
+compositions have been found to be possible and their number is growing rapidly
+due to their characteristics that make them ideal for various applications,
+such as fabrication of cathodes for solid oxide fuel cells (SOFCs). Oxide
+powders of LaxSr1-xCo1-y-zFeyMnzO3-{\delta} (x=0.4, 0.6, 0.8, y=0.4, 0.8 and
+z=0.1, 0.2), named LSCFM, were prepared by mixing commercial powders. The
+powders have been investigated as a function of the stoichiometry and the
+crystal structure parameters have been determined using Rietveld analysis. The
+results of the structural analysis for each sintered sample, at low temperature
+sintering (1100 {\omicron}C), have been obtained by considering two cubic
+perovskite phases, for x=0.4 or one cubic and one orthorhombic phase for x=0.6,
+0.8, respectively. Analysis of microstructure has shown a maximum grain size of
+~0.63 {\mu}m. The annealed sample at 1100 {\omicron}C, an almost single phase
+specimen, exhibited an electrical conductivity of 1.29\times103 ({\Omega} \cdot
+cm)-1. The sintered sample at 1250 {\omicron}C has higher conductivity but
+sharper curve close to the maximum. We suggest that low temperature sintering
+reveal two phase system with broader curve maximum and high conductivity for
+future applications in SOFCs.",1108.0104v1
+2011-10-12,"Covalency, double-counting and the metal-insulator phase diagram in transition metal oxides","Dynamical mean field theory calculations are used to show that for late
+transition-metal-oxides a critical variable for the Mott/charge-transfer
+transition is the number of d-electrons, which is determined by charge transfer
+from oxygen ions. Insulating behavior is found only for a narrow range of
+d-occupancy, irrespective of the size of the intra-d Coulomb repulsion. The
+result is useful in interpreting 'density functional +U' and 'density
+functional plus dynamical mean field' methods in which additional correlations
+are applied to a specific set of orbitals and an important role is played by
+the 'double counting correction' which dictates the occupancy of these
+correlated orbitals. General considerations are presented and are illustrated
+by calculations for two representative transition metal oxide systems: layered
+perovskite Cu-based ""high-Tc"" materials, an orbitally non-degenerate
+electronically quasi-two dimensional systems, and pseudocubic rare earch
+nickelates, an orbitally degenerate electronically three dimensional system.
+Density functional calculations yield d-occupancies very far from the Mott
+metal-insulator phase boundary in the nickelate materials, but closer to it in
+the cuprates, indicating the sensitivity of theoretical models of the cuprates
+to the choice of double counting correction and corroborating the critical role
+of lattice distortions in attaining the experimentally observed insulating
+phase in the nickelates.",1110.2782v2
+2011-12-28,Behavior of Lithium Oxide at Superionic Transition: First Principles and Molecular Dynamics Studies,"We report studies on the vibrational and elastic behavior of lithium oxide,
+Li2O around its superionic transition temperature. Phonon frequencies
+calculated using the ab-initio and empirical potential model are in excellent
+agreement with the reported experimental data. Further, volume dependence of
+phonon dispersion relation has been calculated, which indicates softening of
+zone boundary transverse acoustic phonon mode along [110] at volume
+corresponding to the superionic transition in Li2O. The instability of phonon
+mode could be a precursor leading to the dynamical disorder of the lithium sub
+lattice. Empirical potential model calculations have been carried out to deduce
+the probable direction of lithium diffusion by constructing a super cell
+consisting of 12000 atoms. The barrier energy for lithium ion diffusion from
+one lattice site to another at ambient and elevated temperature has been
+computed. Barrier energy considerations along various symmetry directions
+indicate that [001] is the most favourable direction for lithium diffusion in
+the fast ion phase. This result corroborates our observation of dynamical
+instability in the transverse mode along (110) wave vector. Using molecular
+dynamics simulations we have studied the temperature variation of elastic
+constants, which are important to the high-temperature stability of lithium
+oxide.",1112.6100v1
+2012-08-29,Molecule-Electrode Interface Energetics in Molecular Junction: a Transition Voltage Spectroscopy Study,"We assess the performances of the transition voltage spectroscopy (TVS)
+method to determine the energies of the molecular orbitals involved in the
+electronic transport though molecular junctions. A large number of various
+molecular junctions made with alkyl chains but with different chemical
+structure of the electrode-molecule interfaces are studied. In the case of
+molecular junctions with clean, unoxidized electrode-molecule interfaces, i.e.
+alkylthiols and alkenes directly grafted on Au and hydrogenated Si,
+respectively, we measure transition voltages in the range 0.9 - 1.4 V. We
+conclude that the TVS method allows estimating the onset of the tail of the
+LUMO density of states, at energy located 1.0 - 1.2 eV above the electrode
+Fermi energy. For oxidized interfaces (e.g. the same monolayer measured with Hg
+or eGaIn drops, or monolayers formed on a slightly oxidized silicon substrate),
+lower transition voltages (0.1 - 0.6 V) are systematically measured. These
+values are explained by the presence of oxide-related density of states at
+energies lower than the HOMO-LUMO of the molecules. As such, the TVS method is
+a useful technique to assess the quality of the molecule-electrode interfaces
+in molecular junctions.",1208.5901v1
+2012-12-07,Binding of an oxide layer to a metal: the case of Ti(10-10)/TiO2(100),"We study the chemical nature of the bonding of an oxide layer to the parent
+metal. In order to disentangle chemical effects from strain/misfit,
+Ti(10$\bar{1}$0)/TiO$_{2}$(100) interface has been chosen. We use the density
+functional pseudopotential method which gives good agreement with experiment
+for known properties of bulk and surface Ti and TiO$_2$. Two geometries, a
+film-like model (with free surface in the structure) and a bulk-like model
+(with no free surface in the structure) are used to simulate the interface, in
+each case with different terminations of Ti and TiO$_2$. For the single-oxygen
+interfaces, the interface energy obtained using these two models agree with
+each other; however for the double-oxygen ones, the relative stability is quite
+different. The disturbance to the electronic structure is confined within a few
+atomic layers of the interface. The interfacial bonding is mainly ionic, and
+surprisingly there is more charge transfer from Ti to O in the interface than
+in the bulk. In consequence the Ti/TiO$_2$ interface has stronger binding than
+the bulk of either material. This helps to explain why the oxide forms a
+stable, protective layer on Ti and Ti alloys.",1212.1659v1
+2012-12-12,Correlated Electron Materials and Field Effect Transistors for Logic: A Review,"Correlated electron systems are among the centerpieces of modern condensed
+matter sciences, where many interesting physical phenomena, such as
+metal-insulator transition and high-Tc superconductivity appear. Recent efforts
+have been focused on electrostatic doping of such materials to probe the
+underlying physics without introducing disorder as well as to build
+field-effect transistors that may complement conventional semiconductor
+metal-oxide-semiconductor field effect transistor (MOSFET) technology. This
+review focuses on metal-insulator transition mechanisms in correlated electron
+materials and three-terminal field effect devices utilizing such correlated
+oxides as the channel layer. We first describe how electron-disorder
+interaction, electron-phonon interaction and/or electron correlation in solids
+could modify the electronic properties of materials and lead to metal-insulator
+transitions. Then we analyze experimental efforts toward utilizing these
+transitions in field effect transistors and their underlying principles. It is
+pointed out that correlated electron systems show promise among these various
+materials displaying phase transitions for logic technologies. Furthermore,
+novel phenomena emerging from electronic correlation could enable new
+functionalities in field effect devices. We then briefly review unconventional
+electrostatic gating techniques, such as ionic liquid gating and ferroelectric
+gating, which enables ultra large carrier accumulation density in the
+correlated materials which could in turn lead to phase transitions. The review
+concludes with a brief discussion on the prospects and suggestions for future
+research directions in correlated oxide electronics for information processing.",1212.2684v1
+2012-12-27,Cs in high oxidation states and as a p-block element,"The major chemical feature of an element is the number of electrons available
+for forming chemical bonds. A doctrine rooted in the atomic shell model states
+that the atoms will maintain a complete inner shell while interacting with
+other atoms. Therefore, group IA elements, for example, are invariably stable
+in the +1 charge state because the p electrons of their inner shells do not
+react with other chemical species. This general rule governs our understanding
+of the structures and reactions of matter and has never been challenged. In
+this work, we show for the first time that while mixing with fluorine under
+pressure, Cs atoms will share their 5p electrons and become oxidized to a
+higher charge state. The formal oxidation state can be as high as +5 within the
+pressure range of our study (<200 GPa) and stable Cs2+ and Cs3+ compounds can
+form at lower pressures. While sharing its 5p electrons, Cs behaves like a
+p-block element forming compounds with molecular, covalent, ionic and metallic
+features. Considering the pressure range required for the CsFn compounds, the
+inner shell electrons in other group IA and IIA elements may also bond with F
+or other chemical species under higher pressure.",1212.6290v1
+2013-01-24,First-principles model potentials for lattice-dynamical studies: general methodology and example of application to ferroic perovskite oxides,"We present a scheme to construct model potentials, with parameters computed
+from first principles, for large-scale lattice-dynamical simulations of
+materials. Our method mimics the traditional solid-state approach to the
+investigation of vibrational spectra, i.e., we start from a suitably chosen
+reference configuration of the material and describe its energy as a function
+of arbitrary atomic distortions by means of a Taylor series. Such a form of the
+potential-energy surface is completely general, trivial to formulate for any
+compound, and physically transparent. Further, the approximations involved in
+our effective models are clear-cut, and the precision can be improved in a
+systematic and well-defined fashion. Moreover, such a simple definition allows
+for a straightforward determination of the parameters in the low-order terms of
+the series, as they are the direct result of
+density-functional-perturbation-theory calculations, which greatly simplifies
+the model construction. Here we present such a scheme, discuss a practical and
+versatile methodology for the calculation of the model parameters from first
+principles, and describe our results for two challenging cases in which the
+model potential is strongly anharmonic, namely, ferroic perovskite oxides
+PbTiO3 and SrTiO3. The choice of test materials was partly motivated by
+historical reasons, since our scheme can be viewed as a natural extension of
+(and was initially inspired by) the so-called first-principles effective
+Hamiltonian approach to the investigation of temperature-driven effects in
+ferroelectric perovskite oxides. Thus, the study of these compounds allows us
+to better describe the connections between the effective-Hamiltonian method and
+ours.",1301.5731v1
+2013-07-08,5d transition metal oxide IrO2 as a material for spin current detection,"Devices based on a pure spin current (a flow of spin angular momentum) have
+been attracting increasing attention as key ingredients for low-dissipation
+electronics. To integrate such spintronics devices into charge-based
+technologies, an electric detection of spin current is essential. Inverse spin
+Hall effect converts a spin current into an electric voltage through spin-orbit
+coupling. Noble metals such as Pt and Pd, and also Cu-based alloys, owing to
+the large direct spin Hall effect, have been regarded as potential materials
+for a spin-current injector. Those materials, however, are not promising as a
+spin-current detector based on inverse spin Hall effect. Their spin Hall
+resistivity rho_SH, representing the performance as a detector, is not large
+enough mainly due to their low charge resistivity. Here we demonstrate that
+heavy transition metal oxides can overcome such limitations inherent to
+metal-based spintronics materials. A binary 5d transition metal oxide IrO2,
+owing to its large resistivity as well as a large spin-orbit coupling
+associated with 5d character of conduction electrons, was found to show a
+gigantic rho_SH ~ 38 microohm cm at room temperature, one order of magnitude
+larger than those of noble metals and Cu-based alloys and even comparable to
+those of atomic layer thin film of W and Ta.",1307.2121v1
+2013-10-02,Simulation of a hump structure in the optical scattering rate within a generalized Allen formalism and its application to copper oxide systems,"We propose a possible way to simulate a hump structure in the optical
+scattering rate. The optical scattering rate of correlated charge carriers can
+be defined within an extended Drude model formalism. When some electron and
+hole doped copper oxide systems are in the spin density or charge density wave
+phases they show hump structures in their optical scattering rates. The hump
+structures have not yet been simulated and understood clearly. We are able to
+simulate the hump structure by using a peak followed by a dip feature in the
+normalized density of states within a generalized Allen formalism. We observe
+that reversing the order of the dip and peak gives completely different
+features in the optical scattering rate; a peak-dip (dip peak) results in a
+hump (a valley) in the scattering rate. We also obtain the real part of the
+optical conductivity and reflectance spectra from the simulated optical
+scattering rate and compare them with published experimental spectra. From
+these comparisons we conclude that the peak-dip order can give the hump
+structure, which is observed experimentally in copper oxide systems. Finally we
+fit two published optical spectra with our new model and discuss our results
+and the possible origin of the dip or peak features in the normalized density
+of states.",1310.0698v1
+2013-11-06,Modulating charge density and inelastic optical response in graphene by atmospheric pressure localized intercalation through wrinkles,"The intercalation of an oxide barrier between graphene and its metallic
+substrate for chem- ical vapor deposition is a contamination-free alternative
+to the transfer of graphene to dielectric supports, usually needed for the
+realization of electronic devices. Low-cost pro- cesses, especially at
+atmospheric pressure, are desirable but whether they are achievable remains an
+open question. Combining complementary microscopic analysis, providing
+structural, electronic, vibrational, and chemical information, we demonstrate
+the spontaneous reactive intercalation of 1.5 nm-thick oxide ribbons between
+graphene and an iridium substrate, at atmospheric pressure and room
+temperature. We discover that oxygen-containing molecules needed for forming
+the ribbons are supplied through the graphene wrinkles, which act as tunnels
+for the efficient diffusion of molecules entering their free end. The
+intercalated oxide ribbons are found to modify the graphene-support
+interaction, leading to the formation of quasi-free-standing high quality
+graphene whose charge density is modulated in few 10-100 nm-wide ribbons by a
+few 10^12 cm-2, where the inelastic optical response is changed, due to a
+softening of vibrational modes - red-shifts of Raman G and 2D bands by 6 and 10
+cm-1, respectively.",1311.1357v1
+2013-12-11,Local Electrostatic Imaging of Striped Domain Order in LaAlO3/SrTiO3,"The emerging field of complex oxide interfaces is generically built on one of
+the most celebrated substrates - strontium titanate (SrTiO3). This material
+hosts a range of phenomena, including ferroelasticity, incipient
+ferroelectricity, and most puzzlingly, contested giant piezoelectricity.
+Although these properties may markedly influence the oxide interfaces,
+especially on microscopic length scales, the lack of local probes capable of
+studying such buried systems has left their effects largely unexplored. Here we
+use a scanning charge detector - a nanotube single-electron transistor - to
+noninvasively image the electrostatic landscape and local mechanical response
+in the prototypical LaAlO3/SrTiO3 system with unprecedented sensitivity. Our
+measurements reveal that on microscopic scales SrTiO3 exhibits large anomalous
+piezoelectricity with curious spatial dependence. Through electrostatic imaging
+we unravel the microscopic origin for this extrinsic piezoelectricity,
+demonstrating its direct, quantitative connection to the motion of locally
+ordered tetragonal domains under applied gate voltage. These domains create
+striped potential modulations that can markedly influence the two-dimensional
+electron system at the conducting interface. Our results have broad
+implications to all complex oxide interfaces built on SrTiO3 and demonstrate
+the importance of microscopic structure to the physics of electrons at the
+LaAlO3/SrTiO3 interface.",1312.3343v1
+2014-07-09,Role of charge transfer in catalytic hydrogen oxidation over platinum,"Charge transfer plays the central role in chemisorption and chemical
+reactions at metal surfaces. The Somorjai group in Nano. Lett. {\bf 9}, 3930
+(2009) has reported a chemicurrent, a flux of charge carriers in response to
+$\mathrm{H_2}$ oxidation by $\mathrm{O_2}$ into $\mathrm{H_2O}$ over a platinum
+surface. The nature of the chemicurrent has been debated in the literature;
+explanations both extrinsic and intrinsic to the reaction mechanism have been
+offered. This article suggests a picture behind the chemicurrent experiments,
+which is intrinsic to the mechanism of hydrogen oxidation in a high temperature
+regime. Surface reaction intermediates, $""\mathrm{O^-}""$, $""\mathrm{H^-}""$,
+$""\mathrm{OH^-}""$, are negatively charged while the product, $\mathrm{H_2O}$,
+and reactants, $\mathrm{H_2}$ and $\mathrm{O_2}$, are neutral. Hence, charge
+transfers between the metal and reacting species are inevitable. After
+electrons are transferred from the metal to the interface in dissociative
+oxygen and hydrogen adsorption, translationally excited electrons in the metal
+arise in part as a result of decay of negatively charged transition states in
+reaction steps connecting surface species of different charges,
+$""\mathrm{O^-+H^-}"" \rightleftarrows ""\mathrm{2 e+OH^-}""$ and
+$""\mathrm{OH^-+H^-}""\rightleftarrows ""\mathrm{2 e+H_2O}""$. These transition
+states are the lowest energy configurations possible for changing the charge of
+the negatively charged surface intermediates. In particular, the transition
+state for $""\mathrm{O^-+H^-}"" \rightleftarrows \mathrm{""2 e+OH^-""}$ limits the
+reaction rate. These processes may contribute to the chemicurrent. This picture
+should also apply to other catalytic chemical reactions on metal surfaces that
+proceed through formation of charged surface intermediates and their consequent
+discharge into the metal.",1407.2570v2
+2014-07-24,Macro- and microscopic properties of strontium doped indium oxide,"Solid state synthesis and physical mechanisms of electrical conductivity
+variation in polycrystalline, strontium doped indium oxide In2O3:(SrO)x were
+investigated for materials with different doping levels at different
+temperatures (T=20-300 C) and ambient atmosphere content including humidity and
+low pressure. Gas sensing ability of these compounds as well as the sample
+resistance appeared to increase by 4 and 8 orders of the magnitude,
+respectively, with the doping level increase from zero up to x=10%. The
+conductance variation due to doping is explained by two mechanisms:
+acceptor-like electrical activity of Sr as a point defect and appearance of an
+additional phase of SrIn2O4. An unusual property of high level (x=10%) doped
+samples is a possibility of extraordinarily large and fast oxygen exchange with
+ambient atmosphere at not very high temperatures (100-200 C). This peculiarity
+is explained by friable structure of crystallite surface. Friable structure
+provides relatively fast transition of samples from high to low resistive state
+at the expense of high conductance of the near surface layer of the grains.
+Microscopic study of the electro-diffusion process at the surface of oxygen
+deficient samples allowed estimation of the diffusion coefficient of oxygen
+vacancies in the friable surface layer at room temperature as 3x10^(-13)
+cm^2/s, which is by one order of the magnitude smaller than that known for
+amorphous indium oxide films.",1407.6471v1
+2014-10-08,Epitaxial growth of Bi$_2$Pt$_2$O$_7$ pyrochlore,"Certain pyrochlore oxides are among the best oxygen catalysts in alkaline
+media. Hence, exploring epitaxial films of these materials is of great
+fundamental and technological interest. Unfortunately, direct film growth of
+one of the most promising pyrochlores, Bi$_2$Pt$_2$O$_7$, has not yet been
+achieved, owing to the difficulty of oxidizing platinum metal in the precursor
+material to Pt$^{4+}$. In this work, in order to induce oxidation of the
+platinum, we annealed pulsed laser deposited films consisting of epitaxial
+$\delta$-Bi$_2$O$_3$ and co-deposited, comparatively disordered platinum. We
+present synchrotron x-ray diffraction results that show the annealed films are
+the first epitaxial crystals of Bi$_2$Pt$_2$O$_7$. We also visualized the
+pyrochlore structure by scanning transmission electron microscopy, and observed
+ordered cation vacancies in a bismuth-rich film but not in a platinum-rich
+film. The similarity between the $\delta$-Bi$_2$O$_3$ and Bi$_2$Pt$_2$O$_7$
+structures appears to facilitate the pyrochlore formation. These results
+constitute a new approach for synthesis of novel pyrochlore thin film oxygen
+catalysts.",1410.2307v1
+2015-02-12,CO Oxidation Catalysed by Pd-based Bimetallic Nanoalloys,"Density functional theory based global geometry optimization has been used to
+demonstrate the crucial influence of the geometry of the catalytic cluster on
+the energy barriers for the CO oxidation reaction over Pd-based bimetallic
+nanoalloys. We show that dramatic geometry change between the reaction
+intermediates can lead to very high energy barriers and thus be prohibitive for
+the whole process. This introduces challenges for both the design of new
+catalysts, and theoretical methods employed. On the theory side, a careful
+choice of geometric configurations of all reaction intermediates is crucial for
+an adequate description of a possible reaction path. From the point of view of
+the catalyst design, the cluster geometry can be controlled by adjusting the
+level of interaction between the cluster and the dopant metal, as well as
+between the adsorbate molecules and the catalyst cluster by mixing different
+metals in a single nanoalloy particle. We show that substitution of a Pd atom
+in the Pd$_{5}$ cluster with a single Ag atom to form Pd$_{4}$Ag$_{1}$ leads to
+a potential improvement of the catalytic properties of the cluster for the CO
+oxidation reaction. On the other hand, a single Au atom does not enhance the
+properties of the catalyst, which is attributed to a weaker hybridization
+between the cluster's constituent metals and the adsorbate molecules. Such
+flexibility of properties of bimetallic nanoalloy clusters illustrates the
+possibility of fine-tuning, which might be used for design of novel efficient
+catalytic materials.",1502.03617v1
+2015-03-03,Crossover of electron-electron interaction effect in Sn-doped indium oxide films,"We systematically study the structures and electrical transport properties of
+a series of Sn-doped indium oxide (ITO) films with thickness $t$ ranging from
+$\sim$5 to $\sim$53\,nm. Scanning electron microscopy and x-ray diffraction
+results indicate that the $t\lesssim 16.8$\,nm films are polycrystalline, while
+those $t\gtrsim 26.7$\,nm films are epitaxially grown along [100] direction.
+For the epitaxial films, the Altshuler and Aronov electron-electron interaction
+(EEI) effect governs the temperature behaviors of the sheet conductance
+$\sigma_\square$ at low temperatures, and the ratios of relative change of Hall
+coefficient $\Delta R_H/R_H$ to relative change of sheet resistance $\Delta
+R_\square/R_\square$ are $\approx$2, which is quantitatively consistent with
+Altshuler and Aronov EEI theory and seldom observed in other systems. For those
+polycrystalline films, both the sheet conductance and Hall coefficient vary
+linearly with logarithm of temperature below several tens Kelvin, which can be
+well described by the current EEI theories in granular metals. We extract the
+intergranular tunneling conductance of each film by comparing the
+$\sigma_\square(T)$ data with the predication of EEI theories in granular
+metals. It is found that when the tunneling conductance is less than the
+conductance of a single indium tin oxide (ITO) grain, the ITO film reveals
+granular metal characteristics in transport properties, conversely, the film
+shows transport properties of homogeneous disordered conductors. Our results
+indicate that electrical transport measurement can not only reveal the
+underlying charge transport properties of the film but also be a powerful tool
+to detect the subtle homogeneity of the film.",1503.00863v2
+2015-03-25,Anisotropy of Thermal Conductivity of Free-Standing Reduced Graphene Oxide Films Annealed at High Temperature,"We investigated thermal conductivity of free-standing reduced graphene oxide
+films subjected to a high-temperature treatment of up to 1000 C. It was found
+that the high-temperature annealing dramatically increased the in-plane thermal
+conductivity, K, of the films from 3 W/mK to 61 W/mK at room temperature. The
+cross-plane thermal conductivity, Kc, revealed an interesting opposite trend of
+decreasing to a very small value of 0.09 W/mK in the reduced graphene oxide
+films annealed at 1000 C. The obtained films demonstrated an exceptionally
+strong anisotropy of the thermal conductivity, K/Kc ~ 675, which is
+substantially larger even than in the high-quality graphite. The electrical
+resistivity of the annealed films reduced to 1 - 19 Ohms/sq. The observed
+modifications of the in-plane and cross-plane thermal conductivity components
+resulting in an unusual K/Kc anisotropy were explained theoretically. The
+theoretical analysis suggests that K can reach as high as ~500 W/mK with the
+increase in the sp2 domain size and further reduction of the oxygen content.
+The strongly anisotropic heat conduction properties of these films can be
+useful for applications in thermal management.",1503.07239v1
+2015-08-12,Mottness at finite doping and charge-instabilities in cuprates,"The intrinsic instability of underdoped copper oxides towards inhomogeneous
+states is one of the central puzzles of the physics of correlated materials.
+The influence of the Mott physics on the doping-temperature phase diagram of
+copper oxides represents a major issue that is subject of intense theoretical
+and experimental effort. Here, we investigate the ultrafast electron dynamics
+in prototypical single-layer Bi-based cuprates at the energy scale of the
+O-2p$\rightarrow$Cu-3d charge-transfer (CT) process. We demonstrate a clear
+evolution of the CT excitations from incoherent and localized, as in a Mott
+insulator, to coherent and delocalized, as in a conventional metal. This
+reorganization of the high-energy degrees of freedom occurs at the critical
+doping p$_{cr}\simeq$0.16 irrespective of the temperature, and it can be well
+described by dynamical mean field theory calculations. We argue that the onset
+of the low-temperature charge instabilities is the low-energy manifestation of
+the underlying Mottness that characterizes the p<p$_{cr}$ region of the phase
+diagram. This discovery sets a new framework for theories of charge order and
+low-temperature phases in underdoped copper oxides.",1508.03075v3
+2015-11-06,Experimental Demonstration of Single Electron Transistors Featuring SiO2 PEALD in Ni-SiO2-Ni Tunnel Junctions,"We report the use of plasma-enhanced atomic layer deposition (PEALD) to
+fabricate single-electron transistors (SETs) featuring ultra-thin (~1 nm)
+tunnel-transparent SiO2 in Ni-SiO2-Ni tunnel junctions. We show that as a
+result of the O2 plasma steps in PEALD of SiO2, the top surface of the
+underlying Ni electrode is oxidized. Additionally, the bottom surface of the
+upper Ni layer is also oxidized where it is in contact with the deposited SiO2,
+most likely as a result of oxygen-containing species on the surface of the
+SiO2. Due to the presence of these surface parasitic layers of NiO, which
+exhibit features typical of thermally activated transport, the resistance of
+Ni-SiO2-Ni tunnel junctions is drastically increased. Moreover, the transport
+mechanism is changed from quantum tunneling through the dielectric barrier to
+one consistent with thermally activated resistors in series with tunnel
+junctions. The reduction of NiO to Ni is therefore required to restore the
+metal-insulator-metal (MIM) structure of the junctions. Rapid thermal annealing
+in a forming gas ambient at elevated temperatures is presented as a technique
+to reduce both parasitic oxide layers. This method is of great interest for
+devices that rely on MIM tunnel junctions with ultra-thin barriers. Using this
+technique, we successfully fabricated MIM SETs with minimal trace of parasitic
+NiO component. We demonstrate that the properties of the tunnel barrier in
+nanoscale tunnel junctions can be evaluated by electrical characterization of
+SETs.",1511.01980v1
+2015-11-17,Accurate First-Principles Electrochemical Phase Diagrams for Ti Oxides from Density Functional Calculations,"Developing an accurate simulation method for the electrochemical stability of
+solids, as well as understanding the physics related with its accuracy, is
+critically important for improving the performance of compounds and predicting
+the stability of new materials in aqueous environments. Herein we propose a
+workflow for the accurate calculation of first-principles electrochemical phase
+(Pourbaix) diagrams. With this scheme, we study the electrochemical stabilities
+of Ti and Ti oxides using density-functional theory. First, we find the
+accuracy of an exchange-correlation functional in predicting formation energies
+and electrochemical stabilities is closely related with the electronic exchange
+interaction therein. Second, the metaGGA and hybrid functionals with a more
+precise description of the electronic exchange interaction lead to a systematic
+improvement in the accuracy of the Pourbaix diagrams. Furthermore, we show that
+accurate Ti Pourbaix diagrams also require that thermal effects are included
+through vibrational contributions to the free energy. We then use these
+diagrams to explain various experimental electrochemical phenomena for the
+Ti--O system, and show that if experimental formation energies for Ti oxides,
+which contain contributions from defects owing to their generation at high
+(combustion) temperatures, are directly used to predict room temperature
+Pourbaix diagrams then significant inaccuracies result. In contrast, the
+formation energies from accurate first-principles calculations, e.g., using
+metaGGA and hybrid functionals, are found to be more reliable. Finally to
+facilitate the future application of our accurate electrochemical phase
+equilibria diagrams, the variation of the Ti Pourbaix diagrams with aqueous ion
+concentration is also provided.",1511.05549v1
+2016-01-20,Strongly enhanced Rashba splittings in oxide heterostructure: a tantalite monolayer on BaHfO$_3$,"In the two-dimensional electron gas (2DEG) emerging at the transition metal
+oxide surface and interface, it has been pointed out that the Rashba spin-orbit
+interaction, the momentum-dependent spin splitting due to broken inversion
+symmetry and atomic spin-orbit coupling, can have profound effects on
+electronic ordering in the spin, orbit, and charge channels, and may help give
+rise to exotic phenomena such as ferromagnetism-superconductivity coexistence
+and topological superconductivity. Although a large Rashba splitting is
+expected to improve experimental accessibility of such phenomena, it has not
+been understood how we can maximally enhance this splitting. Here, we present a
+promising route to realize significant Rashba-type band splitting using a thin
+film heterostructure. Based on first-principles methods and analytic model
+analyses, a tantalate monolayer on BaHfO$_3$ is shown to host two-dimensional
+bands originating from Ta $t_{2g}$ states with strong Rashba spin splittings -
+up to nearly 10% of the bandwidth - at both the band minima and saddle points
+due to the maximal breaking of the inversion symmetry. Such 2DEG band structure
+makes this oxide heterostructure a promising platform for realizing both a
+topological superconductor which hosts Majorana fermions and the electron
+correlation physics with strong spin-orbit coupling.",1601.05443v1
+2016-02-22,"The effect of Ta oxygen scavenger layer on HfO$_2$-based resistive switching behavior: thermodynamic stability, electronic structure, and low-bias transport","Reversible resistive switching between high-resistance and low-resistance
+states in metal-oxide-metal heterostructures makes them very interesting for
+applications in random access memories. While recent experimental work has
+shown that inserting a metallic ""oxygen scavenger layer"" between the positive
+electrode and oxide improves device performance, the fundamental understanding
+of how the scavenger layer modifies heterostructure properties is lacking. We
+use density functional theory to calculate thermodynamic properties and
+conductance of TiN/HfO$_2$/TiN heterostructures with and without Ta scavenger
+layer. First, we show that Ta insertion lowers the formation energy of
+low-resistance states. Second, while the Ta scavenger layer reduces the
+Schottky barrier height in the high-resistance state by modifying the interface
+charge at the oxide-electrode interface, the heterostructure maintains a high
+resistance ratio between high- and low-resistance states. Finally, we show that
+the low-bias conductance of device on-states becomes much less sensitive to the
+spatial distribution of oxygen removed from the HfO$_2$ in the presence of the
+Ta layer. By providing fundamental understanding of the observed improvements
+with scavenger layers, we open a path to engineer interfaces with oxygen
+scavenger layers to control and enhance device performance. In turn, this may
+enable the realization of a non-volatile low-power memory technology with
+concomitant reduction in energy consumption by consumer electronics and
+significant benefits to society.",1602.06793v1
+2016-03-08,Spatial conductivity mapping of unprotected and capped black phosphorus using microwave microscopy,"Thin layers of black phosphorus present an ideal combination of a 2D material
+with a tunable direct bandgap and high carrier mobility. However the material
+suffers from degradation in ambient conditions due to an oxidation reaction
+which involves water, oxygen and light. We have measured the spatial profile of
+the conductivity on flakes of black phosphorus as a function of time using
+scanning microwave impedance microscopy. A microwave excitation (3 GHz) allows
+to image a conducting sample even when covered with a dielectric layer. We
+observe that on bare black phosphorus, the conductivity changes drastically
+over the whole surface within a day. We demonstrate that the degradation
+process is slowed down considerably by covering the material with a 10 nm layer
+of hafnium oxide. It is stable for more than a week, opening up a route towards
+stable black phosphorus devices in which the high dielectric constant of
+hafnium oxide can be exploited. Covering black phosphorus with a 15 nm boron
+nitride flake changes the degradation process qualitatively, it is dominated by
+the edges of the flake indicating a diffusive process and happens on the scale
+of days.",1603.02733v1
+2016-06-04,Electrical characterization of chemical and dielectric passivation of InAs nanowires,"The native oxide at the surface of III-V nanowires, such as InAs, can be a
+major source of charge noise and scattering in nanowire-based electronics,
+particularly for quantum devices operated at low temperatures. Surface
+passivation provides a means to remove the native oxide and prevent its
+regrowth. Here, we study the effects of surface passivation and conformal
+dielectric deposition by measuring electrical conductance through nanowire
+field effect transistors treated with a variety of surface preparations. By
+extracting field effect mobility, subthreshold swing, threshold shift with
+temperature, and the gate hysteresis for each device, we infer the relative
+effects of the different treatments on the factors influencing transport. It is
+found that a combination of chemical passivation followed by deposition of an
+aluminum oxide dielectric shell yields the best results compared to the other
+treatments, and comparable to untreated nanowires. Finally, it is shown that an
+entrenched, top-gated device using an optimally treated nanowire can
+successfully form a stable double quantum dot at low temperatures. The device
+has excellent electrostatic tunability owing to the conformal dielectric layer
+and the combination of local top gates and a global back gate.",1606.01405v2
+2016-07-25,Remarkable Hydrogen Storage on Beryllium Oxide Clusters: First Principles Calculations,"Since the current transportation sector is the largest consumer of oil, and
+subsequently responsible for major air pollutants, it is inevitable to use
+alternative renewable sources of energies for vehicular applications. The
+hydrogen energy seems to be a promising candidate. To explore the possibility
+of achieving a solid-state high-capacity storage of hydrogen for onboard
+applications, we have performed first principles density functional theoretical
+calculations of hydrogen storage properties of beryllium oxide clusters
+(BeO)$_{n}$ (n=2 -- 8). We observed that polar BeO bond is responsible for
+H$_{2}$ adsorption. The problem of cohesion of beryllium atoms does not arise,
+as they are an integral part of BeO clusters. The (BeO)$_{n}$ (n=2 -- 8)
+adsorbs 8--12 H$_{2}$ molecules with an adsorption energy in the desirable
+range of reversible hydrogen storage. The gravimetric density of H$_{2}$
+adsorbed on BeO clusters meets the ultimate 7.5 wt% limit, recommended for
+onboard practical applications.
+  In conclusion, beryllium oxide clusters exhibit a remarkable solid-state
+hydrogen storage.",1607.07162v1
+2016-09-04,Effect of thermal annealing on the heat transfer properties of reduced graphite oxide flakes: a nanoscale characterization via scanning thermal microscopy,"This paper reports on the thermal properties of reduced graphite oxide (RGO)
+flakes, studied by means of scanning thermal microscopy (SThM). This technique
+was demonstrated to allow thermal characterization of the flakes with a spatial
+resolution of the order of a few tens of nanometers, while recording nanoscale
+topography at the same time. Several individual RGO flakes were analyzed by
+SThM, both as obtained after conventional thermal reduction and after a
+subsequent annealing at 1700{\deg}C. Significant differences in the thermal
+maps were observed between pristine and annealed flakes, reflecting higher heat
+dissipation on annealed RGO flakes compared with pristine ones. This result was
+correlated with the reduction of RGO structure defectiveness. In particular, a
+substantial reduction of oxidized groups and sp3 carbons upon annealing was
+proven by X-ray photoelectron and Raman spectroscopies, while the increase of
+crystalline order was demonstrated by X-ray diffraction, in terms of higher
+correlation lengths both along and perpendicular to the graphene planes.
+Results presented in this paper provide experimental evidence for the
+qualitative correlation between the defectiveness of graphene-related materials
+and their thermal conductivity, which is clearly crucial for the exploitation
+of these materials into thermally conductive nanocomposites.",1609.00998v2
+2016-09-06,Size and density controlled metal nanocluster embedded metal-oxide-semiconductor structure for memory applications,"Metal-nanoclusters (NC), deposited by magnetron-based nanocluster source
+coupled with quadrupole mass filter (QMF) assembly having independent control
+over its size and density, are used in fabricating NC-based non-volatile memory
+(NVM) devices. The effect of diameter and density on the NVM charge storage
+characteristics are presented where Ag is used as the metal NC. The Ag-NC,
+sandwiched between HfO$_2$ tunnel and control oxides, is deposited by using the
+combination of the above two instruments. No annealing is performed at any
+stage of the device fabrication. The largest hysteresis loop area in the
+capacitance-voltage ($C-V$) characteristics of metal-oxide-semiconductor (MOS)
+characteristics is observed for a cluster density of 1 $\times$ 10$^{11}$
+cm$^{-2}$. Further, an NC size dependent hysteresis loop area is observed with
+the MOS devices where the NC diameter is varied from 3 to 1.5 nm keeping the NC
+density at 1 $\times$ 10$^{11}$ cm$^{-2}$. The device performance is found to
+be improved with a reduction of the NC size and shows its best with the NC
+diameter of 1.5 nm. The storage time of the NVM devices also increases with the
+decrease in the NC diameter and exhibits their best performances for the NCs
+with a diameter of 1.5 nm.",1609.01523v1
+2016-09-20,Electron transport properties of sub-3-nm diameter copper nanowires,"Density functional theory and density functional tight-binding are applied to
+model electron transport in copper nanowires of approximately 1 nm and 3 nm
+diameters with varying crystal orientation and surface termination. The copper
+nanowires studied are found to be metallic irrespective of diameter, crystal
+orientation and/or surface termination. Electron transmission is highly
+dependent on crystal orientation and surface termination. Nanowires oriented
+along the [110] crystallographic axis consistently exhibit the highest electron
+transmission while surface oxidized nanowires show significantly reduced
+electron transmission compared to unterminated nanowires. Transmission per unit
+area is calculated in each case, for a given crystal orientation we find that
+this value decreases with diameter for unterminated nanowires but is largely
+unaffected by diameter in surface oxidized nanowires for the size regime
+considered. Transmission pathway plots show that transmission is larger at the
+surface of unterminated nanowires than inside the nanowire and that
+transmission at the nanowire surface is significantly reduced by surface
+oxidation. Finally, we present a simple model which explains the transport per
+unit area dependence on diameter based on transmission pathways results.",1609.06160v1
+2016-09-21,Highly efficient and tuneable spin-to-charge conversion through Rashba coupling at oxide interfaces,"The spin-orbit interaction couples the electrons' motion to their spin.
+Accordingly, passing a current in a material with strong spin-orbit coupling
+generates a transverse spin current (spin Hall effect, SHE) and vice-versa
+(inverse spin Hall effect, ISHE). The emergence of SHE and ISHE as
+charge-to-spin interconversion mechanisms offers a variety of novel spintronics
+functionalities and devices, some of which do not require any ferromagnetic
+material. However, the interconversion efficiency of SHE and ISHE (spin Hall
+angle) is a bulk property that rarely exceeds ten percent, and does not take
+advantage of interfacial and low-dimensional effects otherwise ubiquitous in
+spintronics hetero- and mesostructures. Here, we make use of an
+interface-driven spin-orbit coupling mechanism - the Rashba effect - in the
+oxide two-dimensional electron system (2DES) LaAlO3/SrTiO3 to achieve
+spin-to-charge conversion with unprecedented efficiency. Through spin-pumping,
+we inject a spin current from a NiFe film into the oxide 2DES and detect the
+resulting charge current, which can be strongly modulated by a gate voltage. We
+discuss the amplitude of the effect and its gate dependence on the basis of the
+electronic structure of the 2DES.",1609.06464v1
+2016-10-06,Automated Phase Mapping with AgileFD and its Application to Light Absorber Discovery in the V-Mn-Nb Oxide System,"Rapid construction of phase diagrams is a central tenet of combinatorial
+materials science with accelerated materials discovery efforts often hampered
+by challenges in interpreting combinatorial x-ray diffraction datasets, which
+we address by developing AgileFD, an artificial intelligence algorithm that
+enables rapid phase mapping from a combinatorial library of x-ray diffraction
+patterns. AgileFD models alloying-based peak shifting through a novel expansion
+of convolutional nonnegative matrix factorization, which not only improves the
+identification of constituent phases but also maps their concentration and
+lattice parameter as a function of composition. By incorporating Gibbs phase
+rule into the algorithm, physically meaningful phase maps are obtained with
+unsupervised operation, and more refined solutions are attained by injecting
+expert knowledge of the system. The algorithm is demonstrated through
+investigation of the V-Mn-Nb oxide system where decomposition of eight oxide
+phases, including two with substantial alloying, provides the first phase map
+for this pseudo-ternary system. This phase map enables interpretation of
+high-throughput band gap data, leading to the discovery of new solar light
+absorbers and the alloying-based tuning of the direct-allowed band-gap energy
+of MnV2O6. The open-source family of AgileFD algorithms can be implemented into
+a broad range of high throughput workflows to accelerate materials discovery.",1610.02005v1
+2016-10-26,Spatially Resolved Electronic Properties of Single-Layer WS$_2$ on Transition Metal Oxides,"There is a substantial interest in the heterostructures of semiconducting
+transition metal dichalcogenides (TMDCs) amongst each other or with arbitrary
+materials, through which the control of the chemical, structural, electronic,
+spintronic, and optical properties can lead to a change in device paradigms. A
+critical need is to understand the interface between TMDCs and insulating
+substrates, for example high-$\kappa$ dielectrics, which can strongly impact
+the electronic properties such as the optical gap. Here we show that the
+chemical and electronic properties of the single-layer (SL) TMDC, WS$_2$, can
+be transferred onto high-$\kappa$ transition metal oxide substrates TiO$_2$ and
+SrTiO$_3$. The resulting samples are much more suitable for measuring their
+electronic and chemical structures with angle-resolved photoemission than their
+native-grown SiO$_2$ substrates. We probe the WS$_2$ on the micron scale across
+100-micron flakes, and find that the occupied electronic structure is exactly
+as predicted for freestanding SL WS$_2$ with a strong spin-orbit splitting of
+420~meV and a direct band gap at the valence band maximum. Our results suggest
+that TMDCs can be combined with arbitrary multi-functional oxides, which may
+introduce alternative means of controlling the optoelectronic properties of
+such materials.",1610.08480v1
+2017-02-13,Design of $n$- and $p$-type oxide thermoelectrics in LaNiO$_3$/SrTiO$_3(001)$ superlattices exploiting interface polarity,"We investigate the structural, electronic, transport, and thermoelectric
+properties of LaNiO$_3$/SrTiO$_3(001)$ superlattices containing either
+exclusively $n$- or $p$-type interfaces or coupled interfaces of opposite
+polarity by using density functional theory calculations with an on-site
+Coulomb repulsion term. The results show that significant octahedral tilts are
+induced in the SrTiO$_3$ part of the superlattice. Moreover, the La-Sr
+distances and Ni-O out-of-plane bond lengths at the interfaces exhibit a
+distinct variation by about $7\,\%$ with the sign of the electrostatic doping.
+In contrast to the much studied LaAlO$_3$/SrTiO$_3$ system, the charge mismatch
+at the interfaces is exclusively accommodated within the LaNiO$_3$ layers,
+whereas the interface polarity leads to a band offset and to the formation of
+an electric field within the coupled superlattice. Features of the electronic
+structure indicate an orbital-selective quantization of quantum well states.
+The potential- and confinement-induced multiband splitting results in complex
+cylindrical Fermi surfaces with a tendency towards nesting that depends on the
+interface polarity. The analysis of the thermoelectric response reveals a
+particularly large positive Seebeck coefficient ($135~\mu$V/K) and a high
+figure of merit ($0.35$) for room-temperature cross-plane transport in the
+$p$-type superlattice that is attributed to the participation of the SrTiO$_3$
+valence band. Superlattices with either $n$- or $p$-type interfaces show
+cross-plane Seebeck coefficients of opposite sign and thus emerge as a platform
+to construct an oxide-based thermoelectric generator with structurally and
+electronically compatible $n$- and $p$-type oxide thermoelectrics.",1702.03898v1
+2017-02-23,Optical Spectra of Open-Shell and Closed-Shell Graphene-Based Molecules,"We have computationally investigated absorption spectra of a specifically
+configured set of graphene-based molecules involving (1) a sp2 bare graphene
+sheet; (2) framed graphene sheets containing different chemical addends
+terminating dangling bonds of edge atoms but keeping sp2 configured basal
+plane; and (3) bulk sp3 graphene sheets resulted from the chemical modification
+occurred at not only the bare sheet circumference but at its basal plane as
+well. Framed molecules, open-shell by nature, present different kinds of
+reduced graphene oxides and present the main building blocks of graphene
+quantum dots. Closed-shell bulk molecules present models of nanosize graphene
+oxide. UHF ground states and ZINDO/S excited states of the molecules were
+analyzed. The UHF-ZINDO/S combination is well coherent in the case of bulk
+molecules for which UHF and RHF ground state results are identical. In the case
+of framed molecules, the incoherence of the UHF and close-shell ZINDO/S
+approaches is revealed in a considerable decreasing of the HOMO-LUMO energy
+gap, which provides unreal drastic red shift of absorption spectra of
+open-shell molecules into IR region. The conclusion is justified by a
+comparative analysis of calculated and experimental data on absorption and
+fluorescence spectra of graphene quantum dots and graphene oxides.",1702.07197v1
+2017-02-25,Serum protein resistant behavior of multisite-bound poly(ethylene glycol) chains onto iron oxide surfaces,"Recent surveys have shown that the number of nanoparticle-based formulations
+actually used at the clinical level is significantly lower than expected a
+decade ago. One reason for this is that the nanoparticle physicochemical
+properties fall short for handling the complexity of biological environments
+and for preventing nonspecific protein adsorption. In this study, we address
+the issue of the interactions of plasma proteins with polymer coated surfaces.
+To this aim, we use a non-covalent grafting-to method to functionalize iron
+oxide sub-10 nm nanoparticles and iron oxide flat substrates, and compare their
+protein responses. The functionalized copolymers consist in alternating
+poly(ethylene glycol) (PEG) chains and phosphonic acid grafted on the same
+backbone. Quartz Crystal Microbalance with dissipation was used to monitor the
+polymer adsorption kinetics and to evaluate the resistance to protein
+adsorption. On flat substrates, functionalized PEG copolymers adsorb and form a
+brush in the moderate or in the highly stretched regimes, with density between
+0.15 and 1.5 nm-2. PEG layers using phosphonic acid as linkers exhibit
+excellent protein resistance. In contrast, layers prepared with carboxylic acid
+as grafting agent exhibit mitigated protein responses and layer
+destructuration. The present study establishes a correlation between the
+long-term stability of PEG coated particles in biofluids and the protein
+resistance of surfaces coated with the same polymers.",1702.07857v1
+2017-02-25,Mott metal-insulator transition in the Doped Hubbard-Holstein model,"Motivated by the current interest in the understanding of the Mott insulators
+away from half filling, observed in many perovskite oxides, we study the Mott
+metal-insulator transition (MIT) in the doped Hubbard-Holstein model using the
+Hatree-Fock mean field theory. The Hubbard-Holstein model is the simplest model
+containing both the Coulomb and the electron-lattice interactions, which are
+important ingredients in the physics of the perovskite oxides. In contrast to
+the half-filled Hubbard model, which always results in a single phase (either
+metallic or insulating), our results show that away from half-filling, a mixed
+phase of metallic and insulating regions occur. As the dopant concentration is
+increased, the metallic part progressively grows in volume, until it exceeds
+the percolation threshold, leading to percolative conduction. This happens
+above a critical dopant concentration $\delta_c$, which, depending on the
+strength of the electron-lattice interaction, can be a significant fraction of
+unity. This means that the material could be insulating even for a substantial
+amount of doping, in contrast to the expectation that doped holes would destroy
+the insulating behavior of the half-filled Hubbard model. Our theory provides a
+framework for the understanding of the density-driven metal-insulator
+transition observed in many complex oxides.",1703.02886v2
+2017-03-21,Electro-Oxidation of Ni42 Steel: A highly Active Bifunctional Electrocatalyst,"Janus type Water-Splitting Catalysts have attracted highest attention as a
+tool of choice for solar to fuel conversion. AISI Ni 42 steel was upon harsh
+anodization converted in a bifunctional electrocatalyst. Oxygen evolution
+reaction- (OER) and hydrogen evolution reaction (HER) are highly efficiently
+and steadfast catalyzed at pH 7, 13, 14, 14.6 (OER) respectively at pH 0, 1,
+13, 14, 14.6 (HER). The current density taken from long-term OER measurements
+in pH 7 buffer solution upon the electro activated steel at 491 mV
+overpotential was around 4 times higher (4 mA/cm2) in comparison with recently
+developed OER electrocatalysts. The very strong voltage-current behavior of the
+catalyst shown in OER polarization experiments at both pH 7 and at pH 13 were
+even superior to those known for IrO2-RuO2. No degradation of the catalyst was
+detected even when conditions close to standard industrial operations were
+applied to the catalyst. A stable Ni-, Fe- oxide based passivating layer
+sufficiently protected the bare metal for further oxidation. Quantitative
+charge to oxygen- (OER) and charge to hydrogen (HER) conversion was confirmed.
+High resolution XPS spectra showed that most likely gamma-NiO(OH) and FeO(OH)
+are the catalytic active OER and NiO is the catalytic active HER species.",1703.07775v1
+2017-03-29,Molecular dynamics simulations and in vitro analysis of the CRMP2 thiol switch,"Collapsin response mediator protein CRMP2 (gene: DPYSL2) is crucial for
+neuronal development. The homotetrameric CRMP2 complex is regulated via two
+mechanisms, first by phosphorylation at, and second by reduction and oxidation
+of the Cys504 residues of two adjacent subunits. Here, we analyzed the effects
+of this redox switch on the protein in vitro combined with force field
+molecular dynamics (MD). Earlier X-ray data contain the structure of the rigid
+body of the molecule but lack the flexible C-terminus with the important sites
+for phosphorylation and redox regulation. An in silico model for this part was
+established by replica exchange simulations and homology modelling, which is
+consistent with results gained from CD spectroscopy with recombinant protein.
+Thermofluor data indicated that the protein aggregates at bivalent ion
+concentrations below 200 mM. In simulations the protein surface was covered at
+these conditions by large amounts of ions, which most likely prevent
+aggregation. A tryptophan residue (Trp295) in close proximity to the forming
+disulfide allowed the measurement of the structural relaxation of the rigid
+body upon reduction by fluorescent quenching. We were also able to determine
+the second order rate constant of CRMP2 oxidation by H2O2. The simulated
+solvent accessible surface of the hydroxyl group of Ser518 significantly
+increased upon reduction of the disulfide bond. Our results give first detailed
+insight in the profound structural changes of the tetrameric CRMP2 due to
+oxidation and indicate a tightly connected regulation by phosphorylation and
+redox modification.",1703.10124v1
+2017-08-13,Maximal Rashba-like spin splitting via kinetic energy-driven inversion symmetry breaking,"Engineering and enhancing inversion symmetry breaking in solids is a major
+goal in condensed matter physics and materials science, as a route to advancing
+new physics and applications ranging from improved ferroelectrics for memory
+devices to materials hosting Majorana zero modes for quantum computing. Here,
+we uncover a new mechanism for realising a much larger energy scale of
+inversion symmetry breaking at surfaces and interfaces than is typically
+achieved. The key ingredient is a pronounced asymmetry of surface hopping
+energies, i.e. a kinetic energy-driven inversion symmetry breaking, whose
+energy scale is pinned at a significant fraction of the bandwidth. We show,
+from spin- and angle-resolved photoemission, how this enables surface states of
+3d and 4d-based transition-metal oxides to surprisingly develop some of the
+largest Rashba-like spin splittings that are known. Our findings open new
+possibilities to produce spin textured states in oxides which exploit the full
+potential of the bare atomic spin-orbit coupling, raising exciting prospects
+for oxide spintronics. More generally, the core structural building blocks
+which enable this are common to numerous materials, providing the prospect of
+enhanced inversion symmetry breaking at judiciously-chosen surfaces of a
+plethora of compounds, and suggesting routes to interfacial control of
+inversion symmetry breaking in designer heterostructures.",1708.03887v1
+2017-08-18,Design of new Mott multiferroics via complete charge transfer: promising candidates for bulk photovoltaics,"Optimal materials to induce bulk photovoltaic effects should lack inversion
+symmetry and have an optical gap matching the energies of visible radiation.
+Ferroelectric perovskite oxides such as BaTiO$_3$ and PbTiO$_3$ exhibit
+substantial polarization and stability, but have the disadvantage of
+excessively large band gaps. We use both density functional theory and
+dynamical mean field theory calculations to design a new class of Mott
+multiferroics--double perovskite oxides $A_2$VFeO$_6$ ($A$=Ba, Pb, etc). While
+neither perovskite $A$VO$_3$ nor $A$FeO$_3$ is ferroelectric, in the double
+perovskite $A_2$VFeO$_6$ a `complete' charge transfer from V to Fe leads to a
+non-bulk-like charge configuration--an empty V-$d$ shell and a half-filled
+Fe-$d$ shell, giving rise to a polarization comparable to that of ferroelectric
+$A$TiO$_3$. Different from nonmagnetic $A$TiO$_3$, the new double perovskite
+oxides have an antiferromagnetic ground state and around room temperatures, are
+paramagnetic Mott insulators. Most importantly, the V $d^0$ state significantly
+reduces the band gap of $A_2$VFeO$_6$, making it smaller than that of
+$A$TiO$_3$ and BiFeO$_3$ and rendering the new multiferroics a promising
+candidate to induce bulk photovoltaic effects.",1708.05506v1
+2017-08-30,Transport properties of the top and bottom surfaces in monolayer MoS2 grown by chemical vapor deposition,"The advantage of MoS2, compared with graphene, is the direct growth on
+various oxide substrates by chemical vapor deposition (CVD) without utilizing
+catalytic metal substrates, which facilitates practical applications for
+electronics. The carrier mobility is, however, degraded from the intrinsic
+limit mainly due to short-range scattering caused by S vacancies formed during
+CVD growth. If the upper limit for the crystallinity of CVD-MoS2 on oxide
+substrates is determined by the MoS2/substrate interaction during growth, it
+will hinder the advantage. In this study, we investigated the interaction
+between monolayer MoS2 and a SiO2/Si substrate and the difference in
+crystallinity between the top and bottom S surfaces due to the MoS2/substrate
+interaction. Raman and photoluminescence spectroscopy indicated that doping and
+strain were induced in MoS2 from the substrate, but they could be removed by
+transferring MoS2 to a new substrate using polymers. The newly developed
+polymer-transfer technique enabled selective transfer of the bottom or top
+surface of CVD-MoS2 onto a new SiO2/Si substrate. The metal-insulator
+transition was clearly observed for both the normal and inverse transfers,
+suggesting that the crystallinity of CVD-MoS2 is high and that the
+crystallinity of the bottom surface interacting with the substrate was similar
+to that of the top free surface. These results provide positive prospects for
+the further improvement of the crystallinity of MoS2 on oxide substrates by
+reconsidering the growth conditions.",1708.09240v1
+2018-02-26,Trilayer TMDC Heterostructures for MOSFETs and Nanobiosensors,"Two dimensional materials such as Transition Metal Dichalcogenides (TMDC) and
+their bi-layer/tri-layer heterostructures have become the focus of intense
+research and investigation in recent years due to their promising applications
+in electronics and optoelectronics. In this work, we have explored device level
+performance of trilayer TMDC heterostructure (MoS2/MX2/MoS2; M=Mo or, W and X=S
+or, Se) Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) in the
+quantum ballistic regime. Our simulation shows that device 'on' current can be
+improved by inserting a WS2 monolayer between two MoS2 monolayers. Application
+of biaxial tensile strain reveals a reduction in drain current which can be
+attributed to the lowering of carrier effective mass with increased tensile
+strain. In addition, it is found that gate underlap geometry improves
+electrostatic device performance by improving sub-threshold swing. However,
+increase in channel resistance reduces drain current. Besides exploring the
+prospect of these materials in device performance, novel trilayer TMDC
+heterostructure double gate Field Effect Transistors (FETs) are proposed for
+sensing Nano biomolecules as well as for pH sensing. Bottom gate operation
+ensures these FETs operating beyond Nernst limit of 59 mV/pH. Simulation
+results found in this work reveal that scaling of bottom gate oxide results in
+better sensitivity while top oxide scaling exhibits an opposite trend. It is
+also found that, for identical operating conditions, proposed TMDC FET pH
+sensors show super-Nernst sensitivity indicating these materials as potential
+candidates in implementing such sensor. Besides pH sensing, all these materials
+show high sensitivity in the sub-threshold region as a channel material in
+nanobiosensor while MoS2/WS2/MoS2 FET shows the least sensitivity among them.",1802.09141v1
+2018-11-06,An optical transmission spectrum of the ultra-hot Jupiter WASP-33b. First indication of AlO in an exoplanet,"There has been increasing progress toward detailed characterization of
+exoplanetary atmospheres, in both observations and theoretical methods.
+Improvements in observational facilities and data reduction and analysis
+techniques are enabling increasingly higher quality spectra, especially from
+ground-based facilities. The high data quality also necessitates concomitant
+improvements in models required to interpret such data. In particular, the
+detection of trace species such as metal oxides has been challenging. Extremely
+irradiated exoplanets (~3000 K) are expected to show oxides with strong
+absorption signals in the optical. However, there are only a few hot Jupiters
+where such signatures have been reported. Here we aim to characterize the
+atmosphere of the ultra-hot Jupiter WASP-33b using two primary transits taken
+18 orbits apart. Our atmospheric retrieval, performed on the combined data
+sets, provides initial constraints on the atmospheric composition of WASP-33b.
+We report a possible indication of aluminum oxide (AlO) at 3.3-sigma
+significance. The data were obtained with the long slit OSIRIS spectrograph
+mounted at the 10-meter Gran Telescopio Canarias. We cleaned the brightness
+variations from the light curves produced by stellar pulsations, and we
+determined the wavelength-dependent variability of the planetary radius caused
+by the atmospheric absorption of stellar light. A simultaneous fit to the two
+transit light curves allowed us to refine the transit parameters, and the
+common wavelength coverage between the two transits served to contrast our
+results. Future observations with HST as well as other large ground-based
+facilities will be able to further constrain the atmospheric chemical
+composition of the planet.",1811.02573v1
+2018-11-09,Oxygen Electromigration and Energy Band Reconstruction Induced by Electrolyte Field Effect at Oxide Interfaces,"Electrolyte gating is a powerful means for tuning the carrier density and
+exploring the resultant modulation of novel properties on solid surfaces.
+However, the mechanism, especially its effect on the oxygen migration and
+electrostatic charging at the oxide heterostructures, is still unclear. Here we
+explore the electrolyte gating on oxygen-deficient interfaces between SrTiO3
+(STO) crystals and LaAlO3 (LAO) overlayer through the measurements of
+electrical transport, X-ray absorption spectroscopy (XAS) and photoluminescence
+(PL) spectra. We found that oxygen vacancies (Ovac) were filled selectively and
+irreversibly after gating due to oxygen electromigration at the amorphous
+LAO/STO interface, resulting in a reconstruction of its interfacial band
+structure. Because of the filling of Ovac, the amorphous interface also showed
+an enhanced electron mobility and quantum oscillation of the conductance.
+Further, the filling effect could be controlled by the degree of the
+crystallinity of the LAO overlayer by varying the growth temperatures. Our
+results reveal the different effects induced by electrolyte gating, providing
+further clues to understand the mechanism of electrolyte gating on buried
+interfaces and also opening a new avenue for constructing high-mobility oxide
+interfaces.",1811.03793v1
+2018-11-12,Low Lattice Thermal Conductivity of a Two-Dimensional Phosphorene Oxide,"A fundamental understanding of the phonon transport mechanism is important
+for optimizing the efficiency of thermoelectric devices. In this study, we
+investigate the thermal transport properties of the oxidized form of
+phosphorene called phosphorene oxide (PO) by solving phonon Boltzmann transport
+equation based on first-principles density functional theory. We reveal that PO
+exhibits a much lower thermal conductivity (2.42-7.08 W/mK, at 300 K) than its
+pristine counterpart as well as other two-dimensional materials. To comprehend
+the physical origin of such low thermal conductivity, we scrutinize the
+contribution of each phonon branch to the thermal conductivity by evaluating
+various mode-dependent quantities including Gruneisen parameters, anharmonic
+threep-honon scattering rate, phase space of three-phonon scattering processes.
+Our results show that its exible puckered structure of PO leads to smaller
+sound velocities; its broken-mirror symmetry allows more ZA phonon scattering;
+and the relatively-free vibration of dangling oxygen atoms in PO gives rise to
+additional scattering resulting in further reduction in the phonon lifetime.
+These results can be verified by the fact that PO has larger phase space for
+three-phonon processes than phosphorene. Furthermore we show that the thermal
+conductivity of PO can be optimized by controlling its size or its phonon mean
+free path, indicating that PO can be a promising candidate for low-dimensional
+thermoelectric devices.",1811.04612v2
+2018-11-20,Towards integrated metatronics: a holistic approach on precise optical and electrical properties of Indium Tin Oxide,"The class of transparent conductive oxides includes the material indium tin
+oxide (ITO) and has become a widely used material of modern every-day life such
+as in touch screens of smart phones and watches, but also used as an optically
+transparent low electrically-resistive contract in the photovoltaics industry.
+More recently ITO has shown epsilon-near-zero (ENZ) behavior in the
+telecommunication frequency band enabling both strong index modulation and
+other optically-exotic applications such as metatronics. However the ability to
+precisely obtain targeted electrical and optical material properties in ITO is
+still challenging due to complex intrinsic effects in ITO and as such no
+integrated metatronic platform has been demonstrated to-date. Here we deliver
+an extensive and accurate description process parameters of RF-sputtering,
+showing a holistic control of the quality of ITO thin films in the visible and
+particularly near-infrared spectral region. We further are able to
+custom-engineer the ENZ point across the telecommunication band by explicitly
+controlling the sputtering process conditions. Exploiting this control we
+design a functional sub-wavelength-scale filter based on lumped
+circuit-elements, towards the realization of integrated metatronic devices and
+circuits.",1811.08344v4
+2019-04-30,Semitransparent Polymer-Based Solar Cells with Aluminum-Doped Zinc Oxide Electrodes,"With the usage of two transparent electrodes, organic solar cells are
+semitransparent and may be combined to parallel-connected multi-junction
+devices or used for innovative applications like power-generating windows. A
+challenging issue is the optimization of the electrodes, in order to combine
+high transparency with adequate electric properties. In the present work, we
+study the potential of sputter-deposited aluminum-doped zinc oxide (AZO) as an
+alternative to the widely used but relatively expensive indium tin oxide (ITO)
+as cathode material in semitransparent polymer-fullerene solar cells.
+Concerning the anode, we utilized an insulator/metal/insulator structure based
+on ultra-thin Au films embedded between two evaporated MoO$_3$ layers, with the
+outer MoO$_3$ film (capping layer) serving as a light coupling layer. The
+performance of the ITO-free semitransparent solar cells is systematically
+studied as dependent on the thickness of the capping layer and the active
+layer, as well as the illumination direction. These variations are found to
+have strong impact on the obtained photocurrent. We performed optical
+simulations of the electric field distribution within the devices to analyze
+the origin of the current variations and provide deep insight in the device
+physics. With the conventional absorber materials studied herein, optimized
+ITO-free and semitransparent devices reached 2.0% power conversion efficiency
+and a maximum optical transmission of 60%, with the device concept being
+potentially transferable to other absorber materials.",1905.00112v1
+2019-05-11,Separating Electrons and Donors in BaSnO3 via Band Engineering,"Through a combination of thin film growth, hard X-ray photoelectron
+spectroscopy (HAXPES), scanning transmission electron microscopy/electron
+energy loss spectroscopy (STEM/EELS), magneto-transport measurements, and
+transport modeling, we report on the demonstration of modulation-doping of
+BaSnO3 (BSO) using a wider bandgap La-doped SrSnO3 (LSSO) layer. Hard X-ray
+photoelectron spectroscopy (HAXPES) revealed a valence band offset of 0.71 +/-
+0.02 eV between LSSO and BSO resulting in a favorable conduction band offset
+for remote doping of BSO using LSSO. Nonlinear Hall effect of LSSO/BSO
+heterostructure confirmed two-channel conduction owing to electron transfer
+from LSSO to BSO and remained in good agreement with the results of
+self-consistent solution to one-dimensional Poisson and Schr\""odinger
+equations. Angle-dependent HAXPES measurements revealed a spatial distribution
+of electrons over 2-3 unit cells in BSO. These results bring perovskite oxides
+a step closer to room-temperature oxide electronics by establishing
+modulation-doping approaches in non-SrTiO3-based oxide heterostructure.",1905.04563v1
+2019-05-26,Plasmonic Light Illumination Creates a Channel to Achieve Fast Degradation of Ti3C2Tx Nanosheets,"Two-dimensional (2D) material-controllable degradation under light radiation
+is crucial for their photonics and medical-related applications, which are yet
+to be investigated. In this paper, we first report the laser illumination
+method to regulate the degradation rate of Ti3C2Tx nanosheets in aqueous
+solution. Comprehensive characterization of intermediates and final products
+confirmed that plasmonic laser promoting the oxidation was strikingly different
+from heating the aqueous solution homogeneously. Laser illumination would
+nearly 10 times accelerate the degradation of Ti3C2Tx nanosheets in initial
+stage and create many smaller-sized oxidized products in a short time.
+Laser-induced fast degradation was principally ascribed to surface plasmonic
+resonance effect of Ti3C2Tx nanosheets. The degradation ability of such
+illumination could be controlled either by tuning the excitation wavelength or
+changing the excitation power. Furthermore, the laser- or thermal-induced
+degradation could be retarded by surface protection of Ti3C2Tx nanosheets. Our
+results suggest that plasmonic electron excitation of Ti3C2Tx nanosheets could
+build a new reaction channel and lead to the fast oxidation of nanosheets in
+aqueous solution, potentially enabling a series of water-based applications.",1905.10839v2
+2019-05-31,Coexistence of polar displacements and conduction in doped ferroelectrics: an ab initio comparative study,"Polar metals are rare because free carriers in metals screen electrostatic
+potential and eliminate internal dipoles. Degenerate doped ferroelectrics may
+create an approximate polar metallic phase. We use first-principles
+calculations to investigate $n$-doped LiNbO$_3$-type oxides (LiNbO$_3$ as the
+prototype) and compare to widely studied perovskite oxides (BaTiO$_3$ as the
+prototype). In the rigid-band approximation, substantial polar displacements in
+$n$-doped LiNbO$_3$ persist even at 0.3 $e$/f.u. ($\simeq$ 10$^{21}$
+cm$^{-3}$), while polar displacements in $n$-doped BaTiO$_3$ quickly get
+suppressed and completely vanish at 0.1 $e$/f.u. Furthermore, in $n$-doped
+LiNbO$_3$, Li-O displacements decay more slowly than Nb-O displacements, while
+in $n$-doped BaTiO$_3$, Ba-O and Ti-O displacements decay approximately at the
+same rate. Supercell calculations that use oxygen vacancies as electron donors
+support the main results from the rigid-band approximation and provide more
+detailed charge distributions. Substantial cation displacements are observed
+throughout LiNbO$_{3-\delta}$($\delta = 4.2\%$), while cation displacements in
+BaTiO$_{3-\delta}$($\delta = 4.2\%$) are almost completely suppressed. We find
+that conduction electrons in LiNbO$_{3-\delta}$ are not as uniformly
+distributed as in BaTiO$_{3-\delta}$, implying that the rigid-band
+approximation should be used with caution in simulating electron doped
+LiNbO$_3$-type oxides. Our work shows that polar distortions and conduction can
+coexist in a wide range of electron concentration in $n$-doped LiNbO$_3$, which
+is a practical approach to generating an approximate polar metallic phase.
+Combining doped ferroelectrics and doped semiconductors may create new
+functions for devices.",1905.13384v1
+2014-03-20,Electronic Properties of Graphene Encapsulated with Different Two-Dimensional Atomic Crystals,"Hexagonal boron nitride is the only substrate that has so far allowed
+graphene devices exhibiting micron-scale ballistic transport. Can other
+atomically flat crystals be used as substrates for making quality graphene
+heterostructures? Here we report on our search for alternative substrates. The
+devices fabricated by encapsulating graphene with molybdenum or tungsten
+disulphides and hBN are found to exhibit consistently high carrier mobilities
+of about 60,000 cm$^{2}$V$^{-1}$s$^{-1}$. In contrast, encapsulation with
+atomically flat layered oxides such as mica, bismuth strontium calcium copper
+oxide and vanadium pentoxide results in exceptionally low quality of graphene
+devices with mobilities of ~ 1,000 cm$^{2}$ V$^{-1}$s$^{-1}$. We attribute the
+difference mainly to self-cleansing that takes place at interfaces between
+graphene, hBN and transition metal dichalcogenides. Surface contamination
+assembles into large pockets allowing the rest of the interface to become
+atomically clean. The cleansing process does not occur for graphene on
+atomically flat oxide substrates.",1403.5225v2
+2014-03-29,Tailored surfaces of perovskite oxide substrates for conducted growth of thin films,"Oxide electronics relies on the availability of epitaxial oxide thin films.
+The extreme flexibility of the chemical composition of ABO3 perovskites and the
+broad spectrum of properties they cover, inspire the creativity of scientists
+and place perovskites in the lead of functional materials for advanced
+technologies. Moreover, emerging properties are being discovered at interfaces
+between distinct perovskites that could not be anticipated on the basis of
+those of the adjacent epitaxial layers. All dreamed new prospects require the
+use of suitable substrates for epitaxial growth. Perovskite single crystals are
+the workhorses of this activity and understanding and controlling their surface
+properties have become critical. In this tutorial review we will chiefly focus
+on the impact of the morphology and composition of the surface of ABO3
+perovskite substrates on the growth mechanisms and properties of thin films
+epitaxially grown on them. As SrTiO3 is the most popular substrate, we will
+mostly concentrate on describing the current understanding and achievements for
+it. Illustrative examples of other perovskite substrates (LaAlO3, LSAT and
+DyScO3) will be also included. We will show that distinct chemical terminations
+can exist on the surfaces used for growth and we will review methods employed
+either to select the most appropriate one for specific growth to allow, for
+instance, tailoring the ultimate outmost epilayer, or to induce self-ordering
+to engineer long-range nanoscale patterns of chemical terminations. We will
+demonstrate the capacity of this knowledge by the growth of low-dimensional
+organic and inorganic structures.",1403.7655v1
+2016-11-09,Importance of strain reduction in improvement of optical transmission and conductance in Si4+ doped ZnO: a probable new moisture resistant Transparent Conductive Oxide,"Si doped ZnO has been reported to be a better conductor than pure ZnO. It is
+reported that carrier density increases and hence conductivity increases.
+However, the effect on optical transmission is yet not clear until our recent
+report [1]. Zn1-xSixO for x= 0, 0.013, 0.020 and 0.027 have been synthesized
+using sol-gel method (a citric acid-glycerol route) followed by solid state
+sintering. We found that there is a decrease in defect states due to Si doping.
+The correlation of strain to the decrement in vacancy sites is discussed in
+this report. In modern electronics and solar cell fabrication, transparent
+conductive oxides (TCOs) are important components which conduct electrically
+without absorbing visible light. Known TCOs are extremely costly and are
+composed of non-abundant elements. Search for new ecofriendly, cheap and
+sustainable TCOs has been a recent research of attraction. Keeping in mind that
+most solar cells are exposed to natural conditions, the humidity tolerance
+becomes a determining factor. We report that sensitivity to moisture decreases
+drastically while the conductivity and optical transparency increases with
+doping. The reduction of strain and improvement of transport properties results
+in increased conductivity of Si doped ZnO pellets, tempting us to envisage this
+material as a probable alternate TCO.",1611.02837v1
+2017-01-03,Conduction Channel Formation and Dissolution Due to Oxygen Thermophoresis/Diffusion in Hafnium Oxide Memristors,"Transition metal oxide memristors, or resistive random-access memory (RRAM)
+switches, are under intense development for storage-class memory because of
+their favorable operating power, endurance, speed, and density. Their
+commercial deployment critically depends on predictive compact models based on
+understanding nanoscale physico-chemical forces, which remains elusive and
+controversial owing to the difficulties in directly observing atomic motions
+during resistive switching, Here, using scanning transmission synchrotron x-ray
+spectromicroscopy to study in-situ switching of hafnium oxide memristors, we
+directly observed the formation of a localized oxygen-deficiency-derived
+conductive channel surrounded by a low-conductivity ring of excess oxygen.
+Subsequent thermal annealing homogenized the segregated oxygen, resetting the
+cells towards their as-grown resistance state. We show that the formation and
+dissolution of the conduction channel are successfully modeled by radial
+thermophoresis and Fick diffusion of oxygen atoms driven by Joule heating. This
+confirmation and quantification of two opposing nanoscale radial forces that
+affect bipolar memristor switching are important components for any future
+physics-based compact model for the electronic switching of these devices.",1701.00864v1
+2017-01-19,Tuneable Sieving of Ions Using Graphene Oxide Membranes,"Graphene oxide membranes show exceptional molecular permeation properties,
+with a promise for many applications. However, their use in ion sieving and
+desalination technologies is limited by a permeation cutoff of ~9 Angstrom,
+which is larger than hydrated ion diameters for common salts. The cutoff is
+determined by the interlayer spacing d ~13.5 Angstrom, typical for graphene
+oxide laminates that swell in water. Achieving smaller d for the laminates
+immersed in water has proved to be a challenge.Here we describe how to control
+d by physical confinement and achieve accurate and tuneable ion sieving.
+Membranes with d from ~ 9.8 Angstrom to 6.4 Angstrom are demonstrated,
+providing the sieve size smaller than typical ions' hydrated diameters.In this
+regime, ion permeation is found to be thermally activated with energy barriers
+of ~10-100 kJ/mol depending on d. Importantly, permeation rates decrease
+exponentially with decreasing the sieve size but water transport is weakly
+affected (by a factor of <2). The latter is attributed to a low barrier for
+water molecules entry and large slip lengths inside graphene capillaries.
+Building on these findings, we demonstrate a simple scalable method to obtain
+graphene-based membranes with limited swelling, which exhibit 97% rejection for
+NaCl.",1701.05519v1
+2017-04-04,Review on Titania Nanopowder- Processing and Applications,"This review work focuses on the milling process of titania (TiO2) nanopowder.
+TiO2 is a naturally available material. It is an inorganic semi-conducting
+oxide of titanium metal. Titanium oxide, titanium dioxide, and titanium (IV)
+oxide are the other names. TiO2 nanopowder is one of the well-known synthetic
+materials in the modern nanotechnology field. It has many interesting,
+lucrative and salient properties. These characters are attracting the
+researchers towards to exploit this material in variety of applications from
+energy to environmental. It is a highly sensitive and excellent photo-catalyst
+material. So, it can be used in gas sensors, in water splitting to generate
+hydrogen, and in waste water treatment to degrade the organic pollutants. It is
+soluble in ethanol, ethylene glycol and chloroform. TiO2 nanopowder is prepared
+by many methods such as sol-gel method, chemical vapour deposition,
+hydro-thermal, micro-emulsion etc. However, low cost and large scale synthesis
+of nanoparticles for commercial applications are the major challenges in the
+present day scenario. Mechanical milling is a simple method to prepare
+nanopowder where milling time plays very important role. The milling time may
+vary from 0 to 60 hour. The crystallinity, phase, size, shape and surface
+features are some of the factors affected by the milling process. For the
+preparation of TiO2 nanomaterial, the mechanical milling is more advantageous
+than other methods. It is a low cost, non toxic method which offers high
+chemical stability. The finely grinded TiO2 nano powder offers shiny surface
+and brilliant colours. Milling of TiO2 is done for size reduction. Doping of
+TiO2 is done to improve the efficiencies and to minimize drawbacks.",1704.00981v1
+2011-11-27,Evolution of structural properties of iron oxide nano particles during temperature treatment from 250°C - 900°C: X-ray diffraction and Fe K-shell pre-edge X-ray absorption study,"Iron oxide nano particles with nominal Fe2O3 stoichiometry were synthesized
+by a wet, soft chemical method with the heat treatment temperatures from
+250{\deg}C to 900{\deg}C in air. The variation in the structural properties of
+the nano particles with the heat treatment temperature was studied by X-ray
+diffraction and Fe K shell X-ray absorption study. X-ray diffractograms show
+that at lower annealing temperatures nano particle comprises both maghemite and
+hematite phases. With increasing temperature, the remainder of the maghemite
+phase transformed completely to hematite. Profile analysis of the leading Bragg
+reflections reveals that the average crystallite size increases from 50 nm to
+150 nm with increasing temperature. The mean primary particle size decreased
+from 105 nm to 90 nm with increasing heat treatment temperature. The X-ray
+diffraction results are paralleled by systematic changes in the pre-edge
+structure of the Fe K-edge X-ray absorption spectra, in particular by a gradual
+decrease of the t2g/eg peak height ratio of the two leading pre-edge
+resonances, confirming oxidation of the Fe from Fe2+ towards Fe3+. Transmission
+electron microscopy (TEM) on the samples treated at temperatures as high as
+900{\deg}C showed particles with prismatic morphology along with the formation
+of stacking fault like defects. High resolution TEM with selected area electron
+diffraction (SAED) of samples heat treated above 350{\deg}C showed that the
+nano particles have well developed lattice fringes corresponding to that of
+(110) plane of hematite.",1111.6204v1
+2012-01-30,Electronic correlations and crystal structure distortions in BaBiO3,"BaBiO3 is a material where formally Bi4+ ions with the half-filled 6s-states
+form the alternating set of Bi3+ and Bi5+ ions resulting in a charge ordered
+insulator. The charge ordering is accompanied by the breathing distortion of
+the BiO6 octahedra (extension and contraction of the Bi-O bond lengths).
+Standard Density Functional Theory (DFT) calculations fail to obtain the
+crystal structure instability caused by the pure breathing distortions.
+Combining effects of the breathing distortions and tilting of the BiO6
+octahedra allows DFT to reproduce qualitatively experimentally observed
+insulator with monoclinic crystal structure but gives strongly underestimate
+breathing distortion parameter and energy gap values. In the present work we
+reexamine the BaBiO3 problem within the GGA+U method using a Wannier functions
+basis set for the Bi 6s-band. Due to high oxidation state of bismuth in this
+material the Bi 6s-symmetry Wannier function is predominantly extended
+spatially on surrounding oxygen ions and hence differs strongly from a pure
+atomic 6s-orbital. That is in sharp contrast to transition metal oxides (with
+exclusion of high oxidation state compounds) where the major part a of d-band
+Wannier function is concentrated on metal ion and a pure atomic d-orbital can
+serve as a good approximation. The GGA+U calculation results agree well with
+experimental data, in particular with experimental crystal structure parameters
+and energy gap values. Moreover, the GGA+U method allows one to reproduce the
+crystal structure instability due to the pure breathing distortions without
+octahedra tilting.",1201.6154v3
+2012-04-24,Structural modification in Au/Si(100) system: Role of surface oxide and vacuum level,"To understand surface structural modifications for Au/Si (100) system, a thin
+gold film of ~2.0 nm was deposited under ultra high vacuum (UHV) condition on
+reconstructed Si surfaces using molecular beam epitaxy (MBE). Post annealing
+was done at 500{\deg}C in three different vacuum conditions: (1) low vacuum
+(LV) furnace (10-2 mbar), (2) UHV (10-10 mbar) (MBE chamber), (3) high vacuum
+(HV) chamber. The variation in the overall shape of the gold nanostructures and
+finer changes at the edges, like rounding of corners has been reported in this
+work. Although well aligned nano rectangles were formed in both HV and LV
+cases, corner rounding is more prominent in LV case. Furthermore in UHV case,
+random structures were formed having sharp corners. In all the above three
+cases, samples were exposed to air (for half an hour) before annealing. To
+study the effect of surface oxide, in-situ annealing inside UHV-MBE chamber was
+done without exposing to air. Well aligned rectangles with sharp corners (no
+corner rounding) were formed. The details about the role of surface oxides in
+the corner rounding process are discussed.",1204.5370v1
+2014-05-09,Impermeable Barrier Films and Protective Coatings Based on Reduced Graphene Oxide,"Barrier films preventing permeation of gases and moistures are important for
+many industries ranging from food to medical and from chemical to electronic.
+From this perspective, graphene has recently attracted particular interest
+because its defect free monolayers are impermeable to all gases and liquids.
+However, it has proved challenging to develop large-area defectless graphene
+films suitable for industrial use. Here we report barrier properties of
+multilayer graphitic films made by chemical reduction of easily and cheaply
+produced graphene oxide laminates. They are found to provide a practically
+perfect barrier that blocks all gases, liquids and aggressive chemicals
+including, for example, hydrofluoric acid. In particular, if graphene oxide
+laminates are reduced in hydroiodic acid, no permeation of hydrogen and water
+could be detected for films as thin as 30 nm, which remain optically
+transparent. The films thicker than 100 nm become completely impermeable. The
+exceptional barrier properties are attributed to a high degree of
+graphitization of the laminates and little structural damage during reduction.
+This work indicates a close prospect of thin protective coatings with stability
+and inertness similar to that of graphene and bulk graphite, which can be
+interesting for numerous applications.",1405.2360v1
+2015-12-14,Quantum interference in an interfacial superconductor,"The two-dimensional superconductor formed at the interface between the
+complex oxides, lanthanum aluminate (LAO) and strontium titanate (STO) has
+several intriguing properties that set it apart from conventional
+superconductors. Most notably, an electric field can be used to tune its
+critical temperature (T$_c$), revealing a dome-shaped phase diagram reminiscent
+of high T$_c$ superconductors. So far, experiments with oxide interfaces have
+measured quantities which probe only the magnitude of the superconducting order
+parameter and are not sensitive to its phase. Here, we perform phase-sensitive
+measurements by realizing the first superconducting quantum interference
+devices (SQUIDs) at the LAO/STO interface. Furthermore, we develop a new
+paradigm for the creation of superconducting circuit elements, where local
+gates enable in-situ creation and control of Josephson junctions. These
+gate-defined SQUIDs are unique in that the entire device is made from a single
+superconductor with purely electrostatic interfaces between the superconducting
+reservoir and the weak link. We complement our experiments with numerical
+simulations and show that the low superfluid density of this interfacial
+superconductor results in a large, gate-controllable kinetic inductance of the
+SQUID. Our observation of robust quantum interference opens up a new pathway to
+understand the nature of superconductivity at oxide interfaces.",1512.04290v3
+2016-05-02,Partial oxidation of Step-Bound Water Leads to Anomalous pH Effects on Metal Electrode Step-Edges,"The design of better heterogeneous catalysts for applications such as fuel
+cells and electrolyzers requires a mechanistic understanding of
+electrocatalytic reactions and the dependence of their activity on operating
+conditions such as pH. A satisfactory explanation for the unexpected pH
+dependence of electrochemical properties of platinum surfaces has so far
+remained elusive, with previous explanations resorting to complex co-adsorption
+of multiple species and resulting in limited predictive power. This knowledge
+gap suggests that the fundamental properties of these catalysts are not yet
+understood, limiting systematic improvement. Here, we analyze the change in
+charge and free energies upon adsorption using density-functional theory (DFT)
+to establish that water adsorbs on platinum step edges across a wide voltage
+range, including the double-layer region, with a loss of approximately 0.2
+electrons upon adsorption. We show how this as-yet unreported change in net
+surface charge due to this water explains the anomalous pH variations of the
+hydrogen underpotential deposition (Hupd) and the potentials of zero total
+charge (PZTC) observed in published experimental data. This partial oxidation
+of water is not limited to platinum metal step edges, and we report the charge
+of the water on metal step edges of commonly used catalytic metals, including
+copper, silver, iridium, and palladium, illustrating that this partial
+oxidation of water broadly influences the reactivity of metal electrodes.",1605.00550v2
+2016-05-19,Shear-Induced Nitric Oxide Production by Endothelial Cells,"We present a biochemical model of the wall shear stress (WSS)-induced
+activation of endothelial nitric oxide synthase (eNOS) in an endothelial cell
+(EC). The model includes three key mechanotransducers: mechanosensing ion
+channels, integrins and G-protein-coupled receptors. The reaction cascade
+consists of two interconnected parts. The first is rapid activation of calcium,
+which results in formation of calcium-calmodulin complexes, followed by
+recruitment of eNOS from caveolae. The second is phosphoryaltion of eNOS by
+protein kinases PKC and AKT. The model also includes a negative feedback loop
+due to inhibition of calcium influx into the cell by cyclic guanosine
+monophosphate (cGMP). In this feedback, increased nitric oxide (NO) levels
+cause an increase in cGMP levels, so that cGMP inhibition of calcium influx can
+limit NO production. The model was used to predict the dynamics of NO
+production by an EC subjected to a step increase of WSS from zero to a finite
+physiologically relevant value. Among several experimentally observed features,
+the model predicts a highly nonlinear, biphasic transient behavior of eNOS
+activation and NO production: a rapid initial activation due to the very rapid
+influx of calcium into the cytosol (occurring within 1 to 5 minutes) is
+followed by a sustained period of activation due to protein kinases.",1605.05804v1
+2016-05-28,"Hubbard interactions in iron-based pnictides and chalcogenides: Slater parametrization, screening channels and frequency dependence","We calculate the strength of the frequency-dependent on-site electronic
+interactions in the iron pnictides LaFeAsO, BaFe2As2, BaRu2As2, and LiFeAs and
+the chalcogenide FeSe from first principles within the constrained random phase
+approximation. We discuss the accuracy of an atomic-like parametrization of the
+two-index density-density interaction matrices based on the calculation of an
+optimal set of three independent Slater integrals, assuming that the angular
+part of the Fe-d localized orbitals can be described within spherical harmonics
+as for isolated Fe atoms. We show that its quality depends on the ligand-metal
+bonding character rather than on the dimensionality of the lattice: it is
+excellent for ionic-like Fe-Se (FeSe) chalcogenides and a more severe
+approximation for more covalent Fe-As (LaFeAsO, BaFe2As2) pnictides. We
+furthermore analyze the relative importance of different screening channels,
+with similar conclusions for the different pnictides but a somewhat different
+picture for the benchmark oxide SrVO3: the ligand channel does not appear to be
+dominant in the pnictides, while oxygen screening is the most important process
+in the oxide. Finally, we analyze the frequency dependence of the interaction.
+In contrast to simple oxides, in iron pnictides its functional form cannot be
+simply modeled by a single plasmon, and the actual density of modes enters the
+construction of an effective Hamiltonian determining the low-energy properties.",1605.08918v1
+2016-12-11,Modeling Nucleation and Growth of Zinc Oxide During Discharge of Primary Zinc-Air Batteries,"Metal-air batteries are among the most promising next-generation energy
+storage devices. Relying on abundant materials and offering high energy
+densities, potential applications lie in the fields of electro-mobility,
+portable electronics, and stationary grid applications. Now, research on
+secondary zinc-air batteries is revived, which are commercialized as primary
+hearing aid batteries. One of the main obstacles for making zinc-air batteries
+rechargeable is their poor lifetime due to the degradation of alkaline
+electrolyte in contact with atmospheric carbon dioxide. In this article, we
+present a continuum theory of a commercial Varta PowerOne button cell. Our
+model contains dissolution of zinc and nucleation and growth of zinc oxide in
+the anode, thermodynamically consistent electrolyte transport in porous media,
+and multi-phase coexistance in the gas diffusion electrode. We perform
+electrochemical measurements and validate our model. Excellent agreement
+between theory and experiment is found and novel insights into the role of zinc
+oxide nucleation and growth and carbon dioxide dissolution for discharge and
+lifetime is presented. We demonstrate the implications of our work for the
+development of rechargeable zinc-air batteries.",1612.03464v2
+2017-06-25,Assessing the performance of self-consistent hybrid functional for band gap calculation in oxide semiconductors,"In this paper we assess the predictive power of the self-consistent hybrid
+functional scPBE0 in calculating the band gap of oxide semiconductors. The
+computational procedure is based on the self-consistent evaluation of the
+mixing parameter $\alpha$ by means of an iterative calculation of the static
+dielectric constant using the perturbation expansion after discretization
+(PEAD) method and making use of the relation $\alpha = 1/\epsilon_{\infty}$.
+Our materials dataset is formed by 30 compounds covering a wide range of band
+gaps and dielectric properties, and includes materials with a wide spectrum of
+application as thermoelectrics, photocatalysis, photovoltaics, transparent
+conducting oxides, and refractory materials. Our results show that the scPBE0
+functional provides better band gaps than the non self-consistent hybrids PBE0
+and HSE06, but scPBE0 does not show significant improvement on the description
+of the static dielectric constants. Overall, the scPBE0 data exhibit a mean
+absolute percentage error of 14 \% (band gaps) and 10 \% ($\epsilon_\infty$).
+For materials with weak dielectric screening and large excitonic biding
+energies scPBE0, unlike PBE0 and HSE06, overestimates the band gaps, but the
+value of the gap become very close to the experimental value when excitonic
+effects are included (e.g. for SiO$_2$). However, special caution must be given
+to the compounds with small band gaps due to the tendency of scPBE0 to
+overestimate the dielectric constant in proximity of the metallic limit.",1706.08159v2
+2017-07-11,Self-Assembling Oxide Catalyst for Electrochemical Water Splitting,"Renewable energy conversion and storage, and greenhouse gas emission-free
+technologies are within the primary tasks and challenges for the society.
+Hydrogen fuel, produced by alkaline water electrolysis is fulfilling all these
+demands, however the technology is economically feeble, limited by the slow
+rate of oxygen evolution reaction. Complex metal oxides were suggested to
+overcome this problem being low-cost efficient catalysts. However, the
+insufficient long-term stability, degradation of structure and electrocatalytic
+activity are restricting their utilization. Here we report on a new
+perovskite-based self-assembling material BaCo0.98Ti0.02O3-$\delta$:Co3O4 with
+superior performance, showing outstanding properties compared to current
+state-of-the-art materials without degeneration of its properties even at 353
+K. By chemical and structural analysis the degradation mechanism was identified
+and modified by selective doping. Short-range order and chemical composition
+rather than long-range order are factors determining the outstanding
+performance. The derived general design rules can be used for further
+development of oxide-based electrocatalytic materials.",1707.03346v1
+2017-07-13,Deuteration of ammonia with D atoms on oxidized partly ASW covered graphite surface,"The deuteration of ammonia by D atoms has been investigated experimentally in
+the sub-monolayer regime on realistic analogues of interstellar dust grain
+surfaces. About 0.8 monolayer of solid NH3 was deposited on top of an oxidized
+graphite surface held at 10 K, partly covered with ASW ice. Ammonia ice is
+subsequently exposed to D atoms for different exposure times using a
+differentially pumped beam-line. The deuteration experiments of ammonia were
+carried out by mass spectroscopy and temperature programmed desorption (TPD)
+technique. The experimental results showed the formation of three isotopologue
+ammonia species by direct exothermic H-D substitution surface reactions:
+NH3+D->NH2D+H, NH2D+D->NHD2+H, and NHD2+D->ND3+H. The formation of the
+deuterated isotopologues NH2D, NHD2, and ND3 at low surface temperature (10 K)
+is likely to occur through quantum tunneling process on the oxidized graphite
+surface. A kinetic model taking into account the diffusion of D atoms on the
+surface is developed to estimate the width and the hight of the activation
+energy barriers for the successive deuteration reactions of ammonia species by
+D atoms. Identical control experiments were performed using CH3OH and D atoms.
+The deuteration process of solid methanol is ruled by H abstraction and D
+addition mechanism, and is almost five orders of magnitude faster than ammonia
+deuteration process.",1707.04063v2
+2017-10-13,"Optical constants of DC sputtering derived ITO, TiO2 and TiO2:Nb thin films characterized by spectrophotometry and spectroscopic ellipsometry for optoelectronic devices","Thin films of inorganic materials as Tin-doped indium oxide, titanium oxide,
+Niobium doped titanium oxide, were deposited for comparison on glass and
+Polyethylene terephthalate (PET) substrates with a DC sputtering method. These
+thin films have been characterized by different techniques: Dektak Surface
+Profilometer, X-ray diffraction (XRD), SEM, (UV/Vis/NIR) spectrophotometer and
+spectroscopic ellipsometry (SE). The optical parameters of these films such as
+transmittance, reflectance, refractive index, extinction coefficient, energy
+gap obtained with different electronic transitions, real and imaginary
+({\epsilon}_r,{\epsilon}_i) dielectric constants, were determined in the
+wavelengths range of (200 - 2200) nm. The results were compared with SE
+measurements in the ranges of (0.56- 6.19) eV by a new amorphous model with
+steps of 1 nm. SE measurements of optical constant have been examined and
+confirm the accuracy of the (UV/Vis/NIR) results. The optical properties
+indicate an excellent transmittance in the visible range of (400 - 800) nm. The
+average transmittance of films on glass is about (86%, 91%, 85%) for (ITO,
+TiO2, TiO2:Nb (NTO)) respectively and decreases to about (85%, 81%, 82%) for
+PET substrates. For all these materials the optical band gap for direct
+transition was (3.53, 3.3, 3.6) eV on glass substrates and on PET substrates
+using two methods (UV and SE). A comparison between optical constants and
+thickness of these ultrathin films observed gives an excellent agreement with
+the UV results. The deposited films were also analyzed by XRD and showed an
+amorphous structure. The structural morphology of these thin films has been
+investigated and compared.",1710.04814v1
+2017-10-27,"Doping Li-rich cathode material Li$_2$MnO$_3$: Interplay between lattice site preference, electronic structure, and delithiation mechanism","We report a detailed first-principles study of doping in Li$_2$MnO$_3$, in
+both the dilute doping limit and heavy doping, using hybrid density-functional
+calculations. We find that Al, Fe, Mo, and Ru impurities are energetically most
+favorable when incorporated into Li$_2$MnO$_3$ at the Mn site, whereas Mg is
+most favorable when doped at the Li sites. Ni, on the other hand, can be
+incorporated at the Li site and/or the Mn site, and the distribution of Ni over
+the lattice sites can be tuned by tuning the materials preparation conditions.
+There is a strong interplay between the lattice site preference and charge and
+spin states of the dopant, the electronic structure of the doped material, and
+the delithiation mechanism. The calculated electronic structure and voltage
+profile indicate that, in Ni-, Mo-, or Ru-doped Li$_2$MnO$_3$, oxidation occurs
+on the electrochemically active transition-metal ion(s) before it does on
+oxygen during the delithiation process. The role of the dopants is to provide
+charge-compensation and bulk electronic conduction mechanisms in the initial
+stages of delithiation, hence enabling the oxidation of the lattice oxygen in
+the later stages. This work thus illustrates how the oxygen-oxidation mechanism
+can be used in combination with the conventional mechanism involving
+transition-metal cations in design of high-capacity battery cathode materials.",1710.10241v2
+2017-12-05,Correlating the nanostructure of Al-oxide with deposition conditions and dielectric contributions of two-level systems in perspective of superconducting quantum circuits,"This work is concerned with Al/Al-oxide(AlO$_{x}$)/Al-layer systems which are
+important for Josephson-junction-based superconducting devices such as quantum
+bits. The device performance is limited by noise, which has been to a large
+degree assigned to the presence and properties of two-level tunneling systems
+in the amorphous AlO$_{x}$ tunnel barrier. The study is focused on the
+correlation of the fabrication conditions, nanostructural and nanochemical
+properties and the occurrence of two-level tunneling systems with particular
+emphasis on the AlO$_{x}$-layer. Electron-beam evaporation with two different
+processes and sputter deposition were used for structure fabrication, and the
+effect of illumination by ultraviolet light during Al-oxide formation is
+elucidated. Characterization was performed by analytical transmission electron
+microscopy and low-temperature dielectric measurements. We show that the
+fabrication conditions have a strong impact on the nanostructural and
+nanochemical properties of the layer systems and the properties of two-level
+tunneling systems. Based on the understanding of the observed structural
+characteristics, routes are derived towards the fabrication of
+Al/AlO$_{x}$/Al-layers systems with improved properties.",1712.01581v1
+2018-01-18,"Material Discovery and Design Principles for Stable, High Activity Perovskite Cathodes for Solid Oxide Fuel Cells","Critical to the development of improved solid oxide fuel cell (SOFC)
+technology are novel compounds with high oxygen reduction reaction (ORR)
+catalytic activity and robust stability under cathode operating conditions.
+Approximately 2145 distinct perovskite compositions are screened for potential
+use as high activity, stable SOFC cathodes, and it is verified that the
+screening methodology qualitatively reproduces the experimental activity,
+stability, and conduction properties of well-studied cathode materials. The
+calculated oxygen p-band center is used as a first principle-based descriptor
+of the surface exchange coefficient (k*), which in turn correlates with cathode
+ORR activity. Convex hull analysis is used under operating conditions in the
+presence of oxygen, hydrogen, and water vapor to determine thermodynamic
+stability. This search has yielded 52 potential cathode materials with good
+predicted stability in typical SOFC operating conditions and predicted k* on
+par with leading ORR perovskite catalysts. The established trends in predicted
+k* and stability are used to suggest methods of improving the performance of
+known promising compounds. The material design strategies and new materials
+discovered in the computational search help enable the development of high
+activity, stable compounds for use in future solid oxide fuel cells and related
+applications.",1801.06109v2
+2018-09-24,Origin of Improved Photoelectrochemical Water Splitting in Mixed Perovskite Oxides,"Owing to the versatility in their chemical and physical properties,
+transition metal perovskite oxides have emerged as a new category of highly
+efficient photocatalysts for photoelectrochemical water splitting. Here, to
+understand the underlying mechanism for the enhanced photoelectrochemical water
+splitting in mixed perovskites, we explore ideal epitaxial thin films of the
+BiFeO3-SrTiO3 system. The electronic struture and carrier dynamics are
+determined from both experiment and density-functional theory calculations. The
+intrinsic phenomena are measured in this ideal sytem, contrasting to commonly
+studied polycrstalline solid solutions where extrinsic structural features
+obscure the intrinsic phenomena. We determined that when SrTiO3 is added to
+BiFeO3 the conduction band minimum position is raised and an exponential tail
+of trap states from hybridized Ti 3d and Fe 3d orbitals emerges near the
+conduction band edge. The presence of these trap states strongly suppresses the
+fast electron-hole recombination and improves the photocurrent density in the
+visible-light region, up to 16 times at 0 VRHE compared to the pure end member
+compositions. Our work provides a new design approach for optimising the
+photoelectrochemical performance in mixed perovksite oxides.",1809.09209v1
+2018-10-06,Two-dimensional honeycomb borophene oxide: Strong anisotropy and nodal loop transformation,"The search for topological semimetals is mainly focused on heavy-element
+compounds as following the footsteps of previous research on topological
+insulators, with less attention on light-element materials. However, the
+negligible spin orbit coupling with light elements may turn out to be
+beneficial for realizing topological band features.Here, using first-principles
+calculations, we propose a new two-dimensional light-element material-the
+honeycomb borophene oxide (h-B2O), which has nontrivial topological
+properties.The proposed structure is based on the recently synthesized
+honeycomb borophene on Al (111) substrate [Sci. Bull. 63, 282 (2018)]. The
+h-B2O monolayer is completely flat, unlike the oxides of graphene or silicene.
+We systematically investigate the structural properties of h-B2O, and find that
+it has very good stability and exhibits significant mechanical anisotropy.
+Interestingly, the electronic band structure of h-B2O hosts a nodal loop
+centered around the Y point in the Brillouin zone, protected by the mirror
+symmetry. Furthermore, under moderate lattice strain, the single nodal loop can
+be transformed into two loops, each penetrating through the Brillouin zone. The
+loops before and after the transition are characterized by different Z*Z
+topological indices. Our work not only predicts a new two-dimensional material
+with interesting physical properties, but also offers an alternative approach
+to search for new topological phases in 2D light-element systems.",1810.03009v2
+2018-10-10,Charge transfer and tunable built-in electric fields across semiconductor-crystalline oxide interfaces,"Built-in electric fields across heterojunctions between semiconducting
+materials underpin the functionality of modern device technologies.
+Heterojunctions between semiconductors and epitaxially grown crystalline oxides
+provide a rich setting in which built-in fields can be explored. Here, we
+present an electrical transport and hard X-ray photoelectron spectroscopy study
+of epitaxial SrNbxTi1-xO3-{\delta} / Si heterojunctions. A non-monotonic
+anomaly in the sheet resistance is observed near room temperature, which is
+accompanied by a crossover in sign of the Hall resistance. The crossover is
+consistent with the formation of a hole gas in the Si and the presence of a
+built-in field. Hard X-ray photoelectron spectroscopy measurements reveal
+pronounced asymmetric features in both the SrNbxTi1-xO3-{\delta} and Si
+core-level spectra that we show arise from built-in fields. The extended probe
+depth of hard X-ray photoelectron spectroscopy enables band bending across the
+SrNbxTi1-xO3-{\delta} / Si heterojunction to be spatially mapped. Band
+alignment at the interface and surface depletion in SrNbxTi1-xO3-{\delta} are
+implicated in the formation of the hole gas and built-in fields. Control of
+charge transfer and built-in electric fields across semiconductor-crystalline
+oxide interfaces opens a pathway to novel functional heterojunctions.",1810.04648v1
+2018-10-12,Berry phase engineering at oxide interfaces,"Geometric phases in condensed matter play a central role in topological
+transport phenomena such as the quantum, spin and anomalous Hall effect (AHE).
+In contrast to the quantum Hall effect - which is characterized by a
+topological invariant and robust against perturbations - the AHE depends on the
+Berry curvature of occupied bands at the Fermi level and is therefore highly
+sensitive to subtle changes in the band structure. A unique platform for its
+manipulation is provided by transition metal oxide heterostructures, where
+engineering of emergent electrodynamics becomes possible at atomically sharp
+interfaces. We demonstrate that the Berry curvature and its corresponding
+vector potential can be manipulated by interface engineering of the correlated
+itinerant ferromagnet SrRuO$_3$ (SRO). Measurements of the AHE reveal the
+presence of two interface-tunable spin-polarized conduction channels. Using
+theoretical calculations, we show that the tunability of the AHE at SRO
+interfaces arises from the competition between two topologically non-trivial
+bands. Our results demonstrate how reconstructions at oxide interfaces can be
+used to control emergent electrodynamics on a nanometer-scale, opening new
+routes towards spintronics and topological electronics.",1810.05619v1
+2018-10-18,Gate-tunable superconductivity at SrTiO3 surface realized by Al layer evaporation,"Electronic properties of low dimensional superconductors are determined by
+many-body-effects. This physics has been studied traditionally with
+superconducting thin films, and in recent times with two-dimensional electron
+gases (2DEGs) at oxide interfaces. In this work, we show that a superconducting
+2DEG can be generated by simply evaporating a thin layer of metallic Al under
+ultra-high vacuum on a SrTiO3 crystal, whereby Al oxidizes into amorphous
+insulating alumina, doping the SrTiO3 surface with oxygen vacancies. The
+superconducting critical temperature of the resulting 2DEG is found to be
+tunable with a gate voltage with a maximum value of 360 mK. A gate-induced
+switching between superconducting and resistive states is demonstrated.
+Compared to conventionally-used pulsed-laser deposition (PLD), our work
+simplifies to a large extent the process of fabricating oxide-based
+superconducting 2DEGs. It will make such systems accessible to a broad range of
+experimental techniques useful to understand low-dimensional phase transitions
+and complex many-body-phenomena in electronic systems.",1810.08069v2
+2018-10-19,"Monatomic Co, CoO$_2$, and CoO$_3$ Nanowires on Ir(100) and Pt(100) surfaces: Formation, Structure, and Energetics","In this study we investigate the structural and chemical changes of monatomic
+CoO$_2$ chains grown self-organized on the Ir(100) surface [P. Ferstl et al.,
+PRL 117, 2016, 046101] and on Pt(100) under reducing and oxidizing conditions.
+By a combination of quantitative low-energy electron diffraction, scanning
+tunnelling microscopy, and density functional theory we show that the cobalt
+oxide wires are completely reduced by H$_2$ at temperatures above 320 K and a
+3x1 ordered Ir$_2$Co or Pt$_2$Co surface alloy is formed. Depending on
+temperature the surface alloy on Ir(100) is either hydrogen covered (T < 400 K)
+or clean and eventually undergoes an irreversible order-disorder transition at
+about 570 K. The Pt$_2$Co surface alloy disorders with the desorption of
+hydrogen, whereby Co submerges into subsurface sites. Vice versa, applying
+stronger oxidants than O$_2$ such as NO$_2$ leads to the formation of CoO3
+chains on Ir(100) in a 3x1 superstructure. On Pt(100) such a CoO$_3$ phase
+could not be prepared so far, which however, is due to the UHV conditions of
+our experiments. As revealed by theory this phase will become stable in a
+regime of higher pressure. In general, the structures can be reversibly
+switched on both surfaces using the respective agents O$_2$, NO$_2$ and H$_2$.",1810.08574v1
+2018-10-25,Doping induced site-selective Mott insulating phase in LaFeO$_3$,"Tailoring transport properties of strongly correlated electron systems in a
+controlled fashion counts among the dreams of materials scientists. In copper
+oxides, varying the carrier concentration is a tool to obtain high-temperature
+superconducting phases. In manganites, doping results in exotic physics such as
+insulator-metal transitions (IMT), colossal magnetoresistance (CMR), orbital-
+or charge-ordered (CO) or charge-disproportionate (CD) states. In most oxides,
+antiferromagnetic order and charge-disproportionation are asssociated with
+insulating behavior. Here we report the realization of a unique physical state
+that can be induced by Mo doping in LaFeO$_3$: the resulting metallic state is
+a site-selective Mott insulator where itinerant electrons evolving in
+low-energy Mo states coexist with localized carriers on the Fe sites. In
+addition, a local breathing-type lattice distortion induces charge
+disproportionation on the latter, without destroying the antiferromagnetic
+order. A state, combining antiferromangetism, metallicity and CD phenomena is
+rather rare in oxides and may be of utmost significance for future
+antiferromagnetic memory devices.",1810.10978v1
+2018-10-26,Mechanical stress dependence of the Fermi level pinning on an oxidized silicon surface,"A combination of micro-Raman spectroscopy and micro-XPS (X-ray photo-electron
+spectroscopy) mapping on statically deflected p-type silicon cantilevers is
+used to study the mechanical stress dependence of the Fermi level pinning at an
+oxidized silicon (001) surface. With uniaxial compressive and tensile stress
+applied parallel to the $\langle$110$\rangle$ crystal direction, the
+observations are relevant to the electronic properties of strain-silicon
+nano-devices with large surface-to-volume ratios such as nanowires and
+nanomembranes. The surface Fermi level pinning is found to be even in applied
+stress, a fact that may be related to the symmetry of the Pb$_0$ silicon/oxide
+interface defects. For stresses up to 160 MPa, an increase in the pinning
+energy of 0.16 meV/MPa is observed for compressive stress, while for tensile
+stress it increases by 0.11 meV/MPa. Using the bulk, valence band deformation
+potentials the reduction in surface band bending in compression (0.09 meV/MPa)
+and in tension (0.13 meV/MPa) can be estimated.",1810.11219v3
+2019-06-13,Chemical and radiative transfer modeling of Propylene Oxide,"The recent identification of the first complex chiral molecule, propylene
+oxide (PrO) in space opens up a new window to further study the origin of
+homochirality on the Earth. There are some recent studies to explain the
+formation of PrO however additional studies on the formation of this species
+are needed for better understanding. We seek to prepare a complete reaction
+network to study the formation of propylene oxide in the astrophysically
+relevant conditions. Based on our results, a detailed radiative transfer
+modeling has been carried out to propose some more transitions which would
+potentially be targeted in the millimeter wave domain. Gas-grain chemical
+network was used to explain the observed abundance of PrO in a cold shell
+surrounding the high-mass star-forming region of Sgr B2. Quantum chemical
+calculations were employed to study various reaction parameters and to compute
+multiple vibrational frequencies of PrO. To model the formation of PrO in the
+observed region, we considered a dark cloud model. Additionally, we used a
+model to check the feasibility of forming PrO in the hot core region. Some
+potential transitions in the millimeter wave domain are predicted which could
+be useful for the future astronomical detection. Radiative transfer modeling
+has been utilized to extract the physical condition which might be useful to
+know the properties of the source in detail. Moreover, vibrational transitions
+of PrO has been provided which could be very useful for the future detection of
+PrO by the upcoming James Webb Space Telescope (JWST).",1906.05604v1
+2019-06-22,Si-incorporated amorphous indium oxide thin-film transistors,"Amorphous oxide semiconductors, especially indium oxide-based (InOx)
+thin-films, have been major candidates for high mobility with easy-to-use
+device processability. As one of the dopants in InOx semiconductors, we
+proposed Si to design a thin-film transistor (TFT) channel. Because the
+suppression of unstable oxygen vacancies in InOx is crucial to maintaining the
+semiconducting behavior, Si was selected as a strong oxygen binder that is
+reasonably available for large production. In this review, we focus on the
+overall properties observed in Si-incorporated amorphous InOx TFTs in terms of
+bond-dissociation energy, Gibbs free energy, Si-concentration dependence of TFT
+properties, carrier transport mechanism, and bias stress instability. In
+comparing low and high doping densities, we found that the activation energy
+and density of states decreased at a high Si concentration in InOx TFTs,
+implying that the trap density was reduced. As a result, stable operation under
+bias stresses could be realized. Furthermore, the inverse Meyer-Neldel rule was
+observed in the highly Si-doped InOx TFT, indicating reasonable ohmic contact.
+Based on our fundamental knowledge of the Si-doped InOx film, we developed a
+high-mobility bilayer TFT with a homogeneous stacked channel that was different
+from a TFT with an etch stop layer structure. The TFT showed remarkably stable
+operation. With simple element components based on InOx, it is possible to
+systematically discuss vacancy engineering in terms of conduction properties.",1906.09366v1
+2019-07-30,Analysis of hydrogen distribution and migration in fired passivating contacts (FPC),"In this work, the hydrogenation mechanism of fired passivating contacts (FPC)
+based on c-Si/SiO$_{x}$/nc-SiC$_{x}$(p) stacks was investigated, by correlating
+the passivation and local re-distribution of hydrogen. Secondary ion mass
+spectroscopy (SIMS) depth profiling was used to assess the hydrogen
+(/deuterium) content. The SIMS profiles show that hydrogen almost completely
+effuses out of the SiC$_{x}$(p) during firing, but can be re-introduced by
+hydrogenation via forming gas anneal (FGA) or by release from a hydrogen
+containing layer such as SiN$_{x}$:H. A pile-up of H at the c-Si/SiO$_{x}$
+interface was observed and identified as a key element in the FPC's passivation
+mechanism. Moreover, the samples hydrogenated with SiN$_{x}$:H exhibited higher
+H content compared to those treated by FGA, resulting in higher iV$_{OC}$
+values. Further investigations revealed that the doping of the SiC$_{x}$ layer
+does not affect the amount of interfacial defects passivated by the
+hydrogenation process presented in this work. Eventually, an effect of the
+oxide's nature on passivation quality is evidenced. iV$_{OC}$ values of up to
+706 mV and 720 mV were reached with FPC test structures using chemical and
+UV-O$_{3}$ tunneling oxides, respectively, and up to 739 mV using a reference
+passivation sample featuring a ~25 nm thick thermal oxide.",1907.13069v1
+2019-09-13,Electric field and current induced electroforming modes in NbOx,"Electroforming is used to initiate the memristive response in
+metal/oxide/metal devices by creating a filamentary conduction path in the
+oxide film. Here we use a simple photoresist-based detection technique to map
+the spatial distribution of conductive filaments formed in Nb/NbOx/Pt devices,
+and correlate these with current-voltage characteristics and in-situ
+thermoreflectance measurements to identify distinct modes of electroforming in
+low and high conductivity NbOx films. In low conductivity films the filaments
+are randomly distributed within the oxide film, consistent with a field-induced
+weakest-link mechanism, while in high conductivity films they are concentrated
+in the center of the film. In the latter case the current-voltage
+characteristics and in-situ thermoreflectance imaging show that electroforming
+is associated with current bifurcation into regions of low and high current
+density. This is supported by finite element modelling of the current
+distribution and shown to be consistent with predictions of a simple core-shell
+model of the current distribution. These results clearly demonstrate two
+distinct modes of electroforming in the same materials system and show that the
+dominant mode depends on the conductivity of the film, with field-induced
+electroforming dominant in low conductivity films and current-bifurcation
+induced electroforming dominant in high conductivity films. Finally, we
+demonstrate S-type and snap-back negative differential resistance in the high
+conductivity films and explain this behavior in terms of two-zone model.",1909.06443v2
+2019-09-16,Presolar Grains in Primitive Ungrouped Carbonaceous Chondrite Northwest Africa 5958,"We report a correlated NanoSIMS-transmission electron microscopy study of the
+ungrouped carbonaceous chondrite Northwest Africa (NWA) 5958. We identified 10
+presolar SiC grains, 2 likely presolar graphite grains, and 20 presolar
+silicate and/or oxide grains in NWA 5958. We suggest a slight modification of
+the commonly used classification system for presolar oxides and silicates that
+better reflects the grains' likely stellar origins. The matrix-normalized
+presolar SiC abundance in NWA 5958 is $18_{-10}^{+15}$ ppm (2$\sigma$), similar
+to that seen in many classes of unmetamorphosed chondrites. In contrast, the
+matrix-normalized abundance of presolar O-rich phases (silicates and oxides) is
+$30.9_{-13.1}^{+17.8}$ ppm (2$\sigma$), much lower than seen in interplanetary
+dust particles and the least altered CR, CO and ungrouped C chondrites, but
+close to that reported for CM chondrites. NanoSIMS mapping also revealed an
+unusual $^{13}$C-enriched ($\delta ^{13}$C$\sim$ 100--200 permil) carbonaceous
+rim surrounding a 1.4 $\mu$m diameter phyllosilicate grain. TEM analysis of two
+presolar grains with a likely origin in asymptotic giant branch stars
+identified one as enstatite and one as Al-Mg spinel with minor Cr. The
+enstatite grain amorphized rapidly under the electron beam, suggesting partial
+hydration. TEM data of NWA 5958 matrix confirm that it has experienced aqueous
+alteration and support the suggestion of Jacquet et al. (2016) that this
+meteorite has affinities to CM2 chondrites.",1909.07225v1
+2019-10-11,Impact of cation redox chemistry on continuous hydrothermal synthesis of 2D-Ni(Co/Fe) hydroxides,"Continuous hydrothermal flow synthesis (CHFS) is a facile, upscalable and
+cost-efficient synthetic method enabling the nanostructuring of advanced
+functional materials in steady conditions, i.e. not in batch synthesis. In this
+paper, we use CHFS to crystallize NiCo- and NiFe-hydroxides in water solution
+with 2D nanofeatures. By tuning the synthetic parameters, we disclose the key
+role of the cation redox chemistry in the transition between two competitive
+phases: from 2D-nanoplatelets of brucite to layered double hydroxides (LDH).
+For controlling the precipitation of different Ni, Fe, Co-hydroxide phases, we
+propose the combined use of an oxidizing (H2O2) and a complexing (NH3) agent.
+At temperatures as low as 80 {\deg}C, the presence of H2O2 and a low
+concentration of NH3 favour the Ni2+/Co3+ over Ni2+/Co2+ oxidation states,
+shifting the product structure from brucite phase (temperatures > 80 {\deg}C)
+to LDH. Conversely, for the NiFe-hydroxides the transition from LDH
+(temperatures < 80 {\deg}C) to brucite phase (temperatures > 80 {\deg}C) is
+controlled by the reaction temperature only. Due to the high stability of Fe3+,
+the synthesis of NiFe products by CHFS does not require oxidizing and
+complexing agents, resulting in a robust process for large-scale production.",1910.05047v1
+2019-10-16,LIPSS on thin metallic films: New insights from multiplicity of laser-excited electromagnetic modes and efficiency of metal oxidation,"Thin Cr films 28-nm thick deposited on glass substrates were processed by
+scanning low-intensity femtosecond laser pulses with energy well below
+single-pulse damage threshold. Two types of laser-induced periodic surface
+structures (LIPSS) were produced, depending on the scanning velocity, (1)
+parallel to laser light polarization with periodicity somewhat smaller than
+laser wavelength and (2) perpendicular to polarization with spatial period much
+smaller than wavelength. All structures are formed as protrusions above the
+initial film surface and exhibit a high degree of oxidation. To explain
+formation of the LIPSS and their conversion from one to another type, a
+rigorous numerical approach for modeling surface electromagnetic waves in
+thin-film geometry has been developed, which takes into account the change of
+optical properties of material due to laser-induced oxidation and porosity. The
+approach addresses the multiplicity of electromagnetic modes allowed for thin
+films. It has been found that the low spatial frequency LIPSS parallel to laser
+polarization, which are formed at low scanning velocities, are well described
+by the Sipe theory for surfaces of low roughness. The SEW mode responsible for
+high spatial frequency LIPSS formation at high scanning velocities has been
+identified. The mechanisms of optical feedback and transformation between types
+of LIPSS with scanning velocity have been proposed.",1910.07280v2
+2019-10-28,Structural and Nanochemical Properties of AlOx Layers in $Al/AlO_x/Al$-Layer Systems for Josephson Junctions,"The structural and nanochemical properties of thin $AlO_x$ layers are
+decisive for the performance of advanced electronic devices. For example, they
+are frequently used as tunnel barriers in Josephson junction-based
+superconducting devices. However, systematic studies of the influence of
+oxidation parameters on structural and nanochemical properties are rare up to
+now, as most studies focus on the electrical properties of $AlO_x$ layers. This
+study aims to close this gap by applying transmission electron microscopy in
+combination with electron energy loss spectroscopy to analyze the structural
+and nanochemical properties of differently fabricated $AlO_x$ layers and
+correlate them with fabrication parameters. With respect to the application of
+$AlO_x$ as tunnel barrier in superconducting Josephson junctions,
+$Al/AlO_x/Al$-layer systems were deposited on Si substrates. We will show that
+the oxygen content and structure of amorphous $AlO_x$ layers is strongly
+dependent on the fabrication process and oxidation parameters. Dynamic and
+static oxidation of Al yields oxygen-deficient amorphous $AlO_x$ layers, where
+the oxygen content ranges from x = 0.5 to x = 1.3 depending on oxygen pressure
+and substrate temperature. Thicker layers of stoichiometric crystalline
+$\gamma-Al_2O_3$ layers were grown by electron-beam evaporation of $Al_2O_3$
+and reactive sputter deposition.",1910.12963v1
+2020-01-03,Scanning Transmission Electron Microscopy of Oxide Interfaces and Heterostructures,"Thin film oxides are a source of endless fascination for the materials
+scientist. These materials are highly flexible, can be integrated into almost
+limitless combinations, and exhibit many useful functionalities for device
+applications. While precision synthesis techniques, such as molecular beam
+epitaxy (MBE) and pulsed laser deposition (PLD), provide a high degree of
+control over these systems, there remains a disconnect between ideal and
+realized materials. Because thin films adopt structures and chemistries
+distinct from their bulk counterparts, it is often difficult to predict what
+properties will emerge. The complex energy landscape of the synthesis process
+is also strongly influenced by non-equilibrium growth conditions imposed by the
+substrate, as well as the kinetics of thin film crystallization and
+fluctuations in process variables, all of which can lead to significant
+deviations from targeted outcomes. High-resolution structural and chemical
+characterization techniques, as described in this volume, are needed to verify
+growth models, bound theoretical calculations, and guide materials design.
+While many characterization options exist, most are spatially-averaged or
+indirect, providing only partial insight into the complex behavior of these
+systems. Over the past several decades, scanning transmission electron
+microscopy (STEM) has become a cornerstone of oxide heterostructure
+characterization owing to its ability to simultaneously resolve structure,
+chemistry, and defects at the highest spatial resolution. STEM methods are an
+essential complement to averaged scattering techniques, offering a direct
+picture of resulting materials that can inform and refine the growth process to
+achieve targeted properties. There is arguably no other technique that can
+provide such a broad array of information at the atomic-scale, all within a
+single experimental session.",2001.00947v2
+2020-01-04,Dielectric/semiconductor interfacial doping to develop solution processed high performance 1 V ambipolar oxide-transistor and its application as CMOS inverter,"p-type doping from the dielectric/semiconductor interface of a SnO2 thin film
+transistor (TFT) has been utilized to develop high carrier mobility balanced
+ambipolar oxide-transistor. To introduce this interfacial-doping, bottom-gate
+top-contact TFTs have been fabricated by using two different ion-conducting
+oxide dielectrics which contain trivalent atoms. These ion-conducting
+dielectrics are LilnO2 and LiGaO2 respectively, containing mobile Li+ ion.
+During SnO2 thin film fabrication on top of the ionic dielectric, those
+trivalent atoms allow p- doping to the interfacial SnO2 layer to introduce the
+hole conduction in channel of TFT. To realize this interfacial doping
+phenomena, a reference TFT has been fabricated with Li2ZnO2 dielectric under
+the same condition that contains divalent zinc (Zn) atom. Our comparative
+electrical data indicates that TFTs with LilnO2 and LiGaO2 dielectric are
+ambipolar in nature whereas, TFT with Li2ZnO2 dielectric is a unipolar
+n-channel transistor which reveals the interfacial doping of SnO2. Most
+interestingly, by using LilnO2 dielectric, we are capable to fabricated 1.0 V
+balanced ambipolar TFT with a high electron and hole mobility values of 7 cm2
+V-1 s-1and 8 cm2 V-1 s-1 respectively with an on/off ratio >102 for both
+operations which has been utilized for low-voltage CMOS inverter fabrication.",2001.01038v1
+2020-01-14,Electron trapping at SiO2/4H-SiC interface probed by transient capacitance measurements and atomic resolution chemical analysis,"Studying the electrical and structural properties of the interface of the
+gate oxide (SiO2) with silicon carbide (4H-SiC) is a fundamental topic, with
+important implications for understanding and optimizing the performances of
+metal-oxide-semiconductor field effect transistor (MOSFETs). In this paper,
+near interface oxide traps (NIOTs) in lateral 4H-SiC MOSFETs were investigated
+combining transient gate capacitance measurements (C-t) and state of the art
+scanning transmission electron microscopy in electron energy loss spectroscopy
+(STEM-EELS) with sub-nm resolution. The C-t measurements as a function of
+temperature indicated that the effective NIOTs discharge time is temperature
+independent and electrons from NIOTs are emitted toward the semiconductor
+via-tunnelling. The NIOTs discharge time was modelled taking into account also
+the interface state density in a tunnelling relaxation model and it allowed to
+locate traps within a tunnelling distance up to 1.3nm from the SiO2/4H-SiC
+interface. On the other hand, sub-nm resolution STEM-EELS revealed the presence
+of a Non-Abrupt (NA) SiO2/4H-SiC interface. The NA interface shows the
+re-arrangement of the carbon atoms in a sub-stoichiometric SiOx matrix. A mixed
+sp2/sp3 carbon hybridization in the NA interface region suggests that the
+interfacial carbon atoms have lost their tetrahedral SiC coordination.",2001.04712v1
+2020-02-27,Structure and morphology of low mechanical loss TiO$_2$-doped Ta$_2$O$_5$,"Amorphous oxide thin films play a fundamental role in state-of-the art
+interferometry experiments, such as gravitational wave detectors where these
+films compose the high reflectance mirrors of end and input masses. The
+sensitivity of these detectors is affected by thermal noise in the mirrors with
+its main source being the mechanical loss of the high index layers. These
+thermally driven fluctuations are a fundamental limit to optical interferometry
+experiments and there is a pressing need to understand the underlying processes
+that lead to mechanical dissipation in materials at room temperature. Two
+strategies are known to lower the mechanical loss: employing a mixture of
+Ta$_2$O$_5$ with $\approx$ 20\% of TiO$_2$ and post-deposition annealing, but
+the reasons behind this are not completely understood. In this work, we present
+a systematic study of the structural and optical properties of ion beam
+sputtered TiO$_2$-doped Ta$_2$O$_5$ films as a function of the annealing
+temperature. We show for the first time that low mechanical loss is associated
+with a material morphology that consists of nanometer sized Ar-rich bubbles
+embedded into an atomically homogeneous mixed titanium-tantalum oxide. When the
+Ti cation ratio is high, however, phase separation occurs in the film which
+leads to increased mechanical loss. These results indicate that for designing
+low mechanical loss mixed oxide coatings for interferometry applications it
+would be beneficial to identify materials with the ability to form ternary
+compounds while the dopant ratio needs to be kept low to avoid phase
+separation.",2002.11866v1
+2020-12-03,Oxygen vacancies in SrTiO$_{3}$ thin films at finite temperatures: A first-principles study,"Epitaxially grown SrTiO$_{3}$ (STO) thin films are material enablers for a
+number of critical energy-conversion and information-storage technologies like
+electrochemical electrode coatings, solid oxide fuel cells and random access
+memories. Oxygen vacancies (${\rm V_{O}}$), on the other hand, are key defects
+to understand and tailor many of the unique functionalities realized in oxide
+perovskite thin films. Here, we present a comprehensive and technically sound
+ab initio description of ${\rm V_{O}}$ in epitaxially strained (001) STO thin
+films. The novelty of our first-principles study lies in the incorporation of
+lattice thermal excitations on the formation energy and diffusion properties of
+${\rm V_{O}}$ over wide epitaxial strain conditions ($-4 \le \eta \le +4$%). We
+found that thermal lattice excitations are necessary to obtain a satisfactory
+agreement between first-principles calculations and the available experimental
+data on the formation energy of ${\rm V_{O}}$ for STO thin films. Furthermore,
+it is shown that thermal lattice excitations noticeably affect the energy
+barriers for oxygen ion diffusion, which strongly depend on $\eta$ and are
+significantly reduced (increased) under tensile (compressive) strain, also in
+consistent agreement with the experimental observations. The present work
+demonstrates that for a realistic theoretical description of oxygen vacancies
+in oxide perovskite thin films is necessary to consider lattice thermal
+excitations, thus going beyond standard zero-temperature ab initio approaches.",2012.01802v1
+2020-12-29,Electronic structure of InAs and InSb surfaces: density functional theory and angle-resolved photoemission spectroscopy,"The electronic structure of surfaces plays a key role in the properties of
+quantum devices. However, surfaces are also the most challenging to simulate
+and engineer. Here, we study the electronic structure of InAs(001), InAs(111),
+and InSb(110) surfaces using a combination of density functional theory (DFT)
+and angle-resolved photoemission spectroscopy (ARPES). We were able to perform
+large-scale first principles simulations and capture effects of different
+surface reconstructions by using DFT calculations with a machine-learned
+Hubbard U correction [npj Comput. Mater. 6, 180 (2020)]. To facilitate direct
+comparison with ARPES results, we implemented a ""bulk unfolding"" scheme by
+projecting the calculated band structure of a supercell surface slab model onto
+the bulk primitive cell. For all three surfaces, we find a good agreement
+between DFT calculations and ARPES. For InAs(001), the simulations clarify the
+effect of the surface reconstruction. Different reconstructions are found to
+produce distinctive surface states. For InAs(111) and InSb(110), the
+simulations help elucidate the effect of oxidation. Owing to larger charge
+transfer from As to O than from Sb to O, oxidation of InAs(111) leads to
+significant band bending and produces an electron pocket, whereas oxidation of
+InSb(110) does not. Our combined theoretical and experimental results may
+inform the design of quantum devices based on InAs and InSb semiconductors,
+e.g., topological qubits utilizing the Majorana zero modes.",2012.14935v1
+2021-01-10,Ionic liquid gating induced two superconductor-insulator phase transitions in spinel oxide Li$_{1 \pm x}$Ti$_2$O$_{4-δ}$,"The associations between emergent physical phenomena (e.g.,
+superconductivity) and orbital, charge, and spin degrees of freedom of $3d$
+electrons are intriguing in transition metal compounds. Here, we successfully
+manipulate the superconductivity of spinel oxide Li$_{1\pm
+x}$Ti$_2$O$_{4-\delta}$ (LTO) by ionic liquid gating. A dome-shaped
+superconducting phase diagram is established, where two insulating phases are
+disclosed both in heavily electron-doping and hole-doping regions. The
+superconductor-insulator transition (SIT) in the hole-doping region can be
+attributed to the loss of Ti valence electrons. In the electron-doping region,
+LTO exhibits an unexpected SIT instead of a metallic behavior despite an
+increase in carrier density. Furthermore, a thermal hysteresis is observed in
+the normal state resistance curve, suggesting a first-order phase transition.
+We speculate that the SIT and the thermal hysteresis stem from the enhanced
+$3d$ electron correlations and the formation of orbital ordering by comparing
+the transport and structural results of LTO with the other spinel oxide
+superconductor MgTi$_2$O$_4$, as well as analysing the electronic structure by
+first-principles calculations. Further comprehension of the detailed interplay
+between superconductivity and orbital ordering would contribute to the
+revealing of unconventional superconducting pairing mechanism.",2101.03518v2
+2017-05-10,Surface oxidation and thermoelectric properties of indium-doped tin telluride nanowires,"The recent discovery of excellent thermoelectric properties and topological
+surface states in SnTe-based compounds has attracted extensive attention in
+various research areas. Indium doped SnTe is of particular interest because,
+depending on the doping level, it can either generate resonant states in the
+bulk valence band leading to enhanced thermoelectric properties, or induce
+superconductivity that coexists with topological states. Here we report on the
+vapor deposition of In-doped SnTe nanowires and the study of their surface
+oxidation and thermoelectric properties. The nanowire growth is assisted by Au
+catalysts, and their morphologies vary as a function of substrate position and
+temperature. Transmission electron microscopy characterization reveals the
+formation of amorphous surface in single crystalline nanowires. X-ray
+photoelectron spectroscopy studies suggest that the nanowire surface is
+composed of In2O3, SnO2, Te and TeO2 which can be readily removed by argon ion
+sputtering. Exposure of the cleaned nanowires to atmosphere yields rapid
+oxidation of the surface within only one minute. Characterizations of
+electrical conductivity {\sigma}, thermopower S, and thermal conductivity
+\k{appa} were performed on the same In-doped nanowire which shows suppressed
+{\sigma} and \k{appa} but enhanced S yielding an improved thermoelectric figure
+of merit ZT than the undoped SnTe.",1705.03874v2
+2017-09-07,Importance of elastic finite-size effects: neutral defects in ionic compounds,"Small system sizes are a well known source of error in DFT calculations, yet
+computational constraints frequently dictate the use of small supercells, often
+as small as 96 atoms in oxides and compound semiconductors. In ionic compounds,
+electrostatic finite size effects have been well characterised, but
+self-interaction of charge neutral defects is often discounted or assumed to
+follow an asymptotic behaviour and thus easily corrected with linear elastic
+theory. Here we show that elastic effects are also important in the description
+of defects in ionic compounds and can lead to qualitatively incorrect
+conclusions if inadequately small supercells are used; moreover, the spurious
+self-interaction does not follow the behaviour predicted by linear elastic
+theory. Considering the exemplar cases of metal oxides with fluorite structure,
+we show that numerous previous studies, employing 96-atom supercells,
+misidentify the ground state structure of (charge neutral) Schottky defects. We
+show that the error is eliminated by employing larger cells (324, 768 and 1500
+atoms), and careful analysis determines that elastic effects, not
+electrostatic, are responsible. The spurious self-interaction was also observed
+in non-oxide ionic compounds and irrespective of the computational method used,
+thereby resolving long standing discrepancies between DFT and force-field
+methods, previously attributed to the level of theory. The surprising magnitude
+of the elastic effects are a cautionary tale for defect calculations in ionic
+materials, particularly when employing computationally expensive methods or
+when modelling large defect clusters. We propose two computationally
+practicable methods to test the magnitude of the elastic self-interaction in
+any ionic system.",1709.02037v1
+2017-08-15,Oxidative species-induced excitonic transport in tubulin aromatic networks: Potential implications for neurodegenerative disease,"Oxidative stress is a pathological hallmark of neurodegenerative tauopathic
+disorders such as Alzheimer's disease and Parkinson's disease-related dementia,
+which are characterized by altered forms of the microtubule-associated protein
+(MAP) tau. MAP tau is a key protein in stabilizing the microtubule architecture
+that regulates neuron morphology and synaptic strength. The precise role of
+reactive oxygen species (ROS) in the tauopathic disease process, however, is
+poorly understood. It is known that the production of ROS by mitochondria can
+result in ultraweak photon emission (UPE) within cells. One likely absorber of
+these photons is the microtubule cytoskeleton, as it forms a vast network
+spanning neurons, is highly co-localized with mitochondria, and shows a high
+density of aromatic amino acids. Functional microtubule networks may traffic
+this ROS-generated endogenous photon energy for cellular signaling, or they may
+serve as dissipaters/conduits of such energy. Experimentally, after in vitro
+exposure to exogenous photons, microtubules have been shown to reorient and
+reorganize in a dose-dependent manner with the greatest effect being observed
+around 280 nm, in the tryptophan and tyrosine absorption range. In this paper,
+recent modeling efforts based on ambient temperature experiment are presented,
+showing that tubulin polymers can feasibly absorb and channel these
+photoexcitations via resonance energy transfer, on the order of dendritic
+length scales. Since microtubule networks are compromised in tauopathic
+diseases, patients with these illnesses would be unable to support effective
+channeling of these photons for signaling or dissipation. Consequent emission
+surplus due to increased UPE production or decreased ability to absorb and
+transfer may lead to increased cellular oxidative damage, thus hastening the
+neurodegenerative process.",1709.03828v1
+2017-09-20,A computational study of hafnia-based ferroelectric memories: from ab initio via physical modeling to circuit models of ferroelectric device,"The discovery of ferroelectric properties of binary oxides revitalized the
+interest in ferroelectrics and bridged the scaling gap between the
+state-of-the-art semiconductor technology and ferroelectric memories. However,
+before hitting the markets, the origin of ferroelectricity and in-depth studies
+of device characteristics are needed. Establishing a correlation between the
+performance of the device and underlying physical mechanisms is the first step
+toward understanding the device and engineering guidelines for a novel,
+superior device. Therefore, in this paper a holistic modeling approaches which
+lead to a better understanding of ferroelectric memories based on hafnium and
+zirconium oxide is addressed. Starting from describing the stabilization of the
+ferroelectric phase within the binary oxides via physical modeling the physical
+mechanisms of the ferroelectric devices are reviewed. Besides, limitations and
+modeling of the multilevel operation and switching kinetics of ultimately
+scaled devices as well as the necessity for Landau-Khalatnikov approach are
+discussed. Furthermore, a device-level model of ferroelectric memory devices
+that can be used to study the array implementation and their operational
+schemes are addressed. Finally, a circuit model of the ferroelectric memory
+device is presented and potential further applications of ferroelectric devices
+are outlined.",1709.06983v1
+2017-11-14,Roughness of oxide glass subcritical fracture surfaces,"An original setup combining a very stable loading stage, an atomic force
+microscope and an environmental chamber, allows to obtain very stable
+sub-critical fracture propagation in oxide glasses under controlled
+environment, and subsequently to finely characterize the nanometric roughness
+properties of the crack surfaces. The analysis of the surface roughness is
+conducted both in terms of the classical root mean square roughness to compare
+with the literature, and in terms of more physically adequate indicators
+related to the self-affine nature of the fracture surfaces. Due to the
+comparable nanometric scale of the surface roughness, the AFM tip size and the
+instrumental noise, a special care is devoted to the statistical evaluation of
+the metrologic properties. The 2 roughness amplitude of several oxide glasses
+was shown to decrease as a function of the stress intensity factor, to be quite
+insensitive to the relative humidity and to increase with the degree of
+heterogeneity of the glass. The results are discussed in terms of several
+modeling arguments concerning the coupling between crack propagation,
+material's heterogeneity, crack tip plastic deformation and water diffusion at
+the crack tip. A synthetic new model is presented combining the predictions of
+a model by Wiederhorn et al. [1] on the effect of the material's heterogeneity
+on the crack tip stresses with the self-affine nature of the fracture surfaces.",1711.05040v1
+2018-03-05,Simulation study of ballistic spin-MOSFET devices with ferromagnetic channels based on some Heusler and oxide compounds,"Newly emerged materials from the family of Heuslers and complex oxides
+exhibit finite bandgaps and ferromagnetic behavior with Curie temperatures much
+higher than even room temperature. In this work, using the semiclassical
+top-of-the-barrier FET model, we explore the operation of a spin-MOSFET that
+utilizes such ferromagnetic semiconductors as channel materials, in addition to
+ferromagnetic source/drain contacts. Such a device could retain the spin
+polarization of injected electrons in the channel, the loss of which limits the
+operation of traditional spin transistors with non-ferromagnetic channels. We
+examine the operation of four material systems that are currently considered
+some of the most prominent known ferromagnetic semiconductors, three
+Heusler-type alloys (Mn2CoAl, CrVZrAl, CoVZrAl) and one from the oxide family
+(NiFe2O4). We describe their bandstructures by using data from DFT
+calculations. We investigate under which conditions high spin polarization and
+significant ION/IOFF ratio, two essential requirements for the spin-MOSFET
+operation, are both achieved. We show that these particular Heusler channels,
+in their bulk form, do not have adequate bandgap to provide high ION/IOFF
+ratios, and have small magnetoconductance compared to state-of-the-art devices.
+However, with confinement into ultra-narrow sizes down to a few nanometers, and
+by engineering their spin dependent contact resistances, they could prove
+promising channel materials for the realization of spin-MOSFET transistor
+devices that offer combined logic and memory functionalities. Although the main
+compounds of interest in this paper are Mn2CoAl, CrVZrAl, CoVZrAl, and NiFe2O4
+alone, we expect that the insight we provide is relevant to other classes of
+such materials as well.",1803.01789v1
+2018-03-06,The enzyme-like catalytic activity of cerium oxide nanoparticles and its dependency on Ce3+ surface area concentration,"Cerium oxide nanoparticles are known to catalyze the decomposition of
+reactive oxygen species such as superoxide radical and hydrogen peroxide.
+Herein, we examine the superoxide dismutase (SOD) and catalase (CAT) mimetic
+catalytic activities of nanoceria and demonstrate the existence of generic
+behaviors. For particles of size 4.5, 7.8, 23 and 28 nm, the SOD and CAT
+catalytic activities exhibit the characteristic shape of a Langmuir isotherm as
+a function of cerium concentration. Results show that the catalytic effects are
+enhanced for smaller particles and for the particles with the largest Ce3+
+fraction. The SOD-like activity obtained from the different samples is found to
+superimpose on a single master curve using the Ce3+ surface area concentration
+as a new variable, indicating the existence of particle independent redox
+mechanisms. For the CAT assays the adsorption of H2O2 molecules at the particle
+surface modulates the efficacy of the decomposition process and must be taken
+into account. We design an amperometry-based experiment to evaluate the H2O2
+adsorption at nanoceria surfaces, leading to the renormalization of the
+particle specific area. Depending on the particle type the amount of adsorbed
+H2O2 molecules varies from 2 to 20 nm-2. The proposed scalings are predictive
+and allow determining SOD and CAT catalytic properties of cerium oxide solely
+from physico-chemical features.",1803.01973v1
+2018-03-21,A First-Principles Study on the Adsorption of Small Molecules on Antimonene: Oxidation Tendency and Stability,"Antimonene, a new group-VA 2D semiconducting material beyond phosphorene, was
+recently synthesized through various approaches and was shown to exhibit a good
+structural integrity in ambient conditions and various interesting properties.
+In this work, we perform systematical first-principles investigations on the
+interactions of antimonene with the small molecules CO, NO, NO2, H2O, O2, NH3
+and H2. It is found that NO, NO2, H2O, O2, and NH3 serve as charge acceptors,
+while CO shows a negligible charge transfer. H2 acts as a charge donor to
+antimonene with the amount of charge transfer being ten times that of H2 on
+phosphorene. The interaction of the O2 molecule with antimonene is much
+stronger than that with phosphorene. Surprisingly, the kinetic barrier for the
+splitting of the O2 molecule on antimonene is low (~0.40 eV), suggesting that
+pristine antimonene may undergo oxidation in ambient conditions, especially at
+elevated temperatures. Fortunately, the acceptor role of H2O on antimonene,
+opposite to a donor role in phosphorene, helps to suppress further structural
+degradation of the oxidized antimonene by preventing the proton transfer
+between water molecules and oxygen species to form acids.",1803.07824v1
+2018-06-06,Unveiling ADP-binding sites and channels in respiratory complexes: Validation of Murburn concept as a holistic explanation for oxidative phosphorylation,"Mitochondrial oxidative phosphorylation (mOxPhos) makes ATP, the energy
+currency of life. Chemiosmosis, a proton centric mechanism, advocates that
+Complex V harnesses a transmembrane potential (TMP) for ATP synthesis. This
+perception of cellular respiration requires oxygen to stay tethered at Complex
+IV (an association inhibited by cyanide) and diffusible reactive oxygen species
+(DROS) are considered wasteful and toxic products. With new mechanistic
+insights on heme and flavin enzymes, an oxygen or DROS centric explanation
+(called murburn concept) was recently proposed for mOxPhos. In the new
+mechanism, TMP is not directly harnessed, protons are a rate limiting reactant
+and DROS within matrix serve as the chemical coupling agents that directly link
+NADH oxidation with ATP synthesis. Herein, we report multiple ADP binding sites
+and solvent accessible DROS channels in respiratory proteins, which validate
+the oxygen or DROS centric power generation (ATP synthesis) system in mOxPhos.
+Since cyanide's heme binding Kd is high (mM), low doses (uM) of cyanide is
+lethal because cyanide disrupts DROS dynamics in mOxPhos. The critical study
+also provides comprehensive arguments against Mitchell's and Boyer's
+explanations and extensive support for murburn concept based holistic
+perspectives for mOxPhos.",1806.02310v1
+2018-06-13,Harmonic Generation from Metal-Oxide and Metal-Metal Boundaries,"We explore the outcomes of detailed microscopic models by calculating second-
+and third-harmonic generation from thin film surfaces with discontinuous
+free-electron densities. These circumstances can occur in structures consisting
+of a simple metal mirror, or arrangements composed of either different metals
+or a metal and a free electron system like a conducting oxide. Using a
+hydrodynamic approach we highlight the case of a gold mirror, and that of a
+two-layer system containing indium tin oxide (ITO) and gold. We assume the gold
+mirror surface is characterized by a free-electron cloud of varying density
+that spills into the vacuum, which as a result of material dispersion exhibits
+epsilon-near-zero conditions and local field enhancement at the surface. For a
+bylayer consisting of a thin ITO and gold films, if the wave is incident from
+the ITO side the electromagnetic field is presented with a free-electron
+discontinuity at the ITO/gold interface, and wavelength-dependent,
+epsilon-near-zero conditions that enhance local fields and conversion
+efficiencies, and determine the surface's emission properties. We evaluate the
+relative significance of additional nonlinear sources that arise when a
+free-electron discontinuity is present, and show that harmonic generation can
+be sensitive to the density of the screening free-electron cloud, and not its
+thickness. Our findings also suggest the possibility to control surface
+harmonic generation through surface charge engineering.",1806.05014v1
+2018-06-14,Synthesis of copper and silver nanoparticles by molecular beam method,"The paper presents the results of investigation of the structure of porous
+condensates of Ag-NaCl and Cu-NaCl composition; chemical and phase compositions
+and dimensions of nanoparticles, produced from the vapour phase by EBPVD
+method. Silver and copper nanoparticles in a porous matrix, when removed from
+vacuum, oxidize in air to lower oxides, and have considerable sorption capacity
+relative to oxygen and moisture. Heating in air is accompanied by lowering of
+porous condensate mass, primarily, due to desorption of physically sorbed
+moisture, as well as afteroxidation to higher oxides due to physically adsorbed
+oxygen. At copper concentrations up to 10 at.%, sorption capacity of the
+condensate is greatly enhanced, that is attributable to presence of very fine
+nanoparticles. Increase of copper concentration in the condensate is
+accompanied by lowering of sorption capacity of nanoparticles with respect to
+oxygen, and, therefore, also change of phase composition. In addition to
+concentration change, phase composition of nanoparticles can be also controlled
+by heat treatment of the initial condensate produced at low condensation
+temperatures. Silver and copper nanoparticles can be converted into stable
+colloidal systems.",1806.05509v1
+2018-06-14,Resolving interfacial charge transfer in titanate superlattices using resonant X-ray reflectometry,"Charge transfer in oxide heterostructures can be tuned to promote emergent
+interfacial states, and accordingly, has been the subject of intense study in
+recent years. However, accessing the physics at these interfaces, which are
+often buried deep below the sample surface, remains difficult. Addressing this
+challenge requires techniques capable of measuring the local electronic
+structure with high-resolution depth dependence. Here, we have used
+linearly-polarized resonant X-ray reflectometry (RXR) as a means to visualize
+charge transfer in oxide superlattices with atomic layer precision. From our
+RXR measurements, we extract valence depth profiles of SmTiO$_3$
+(SmTO)/SrTiO$_3$ (STO) heterostructures with STO quantum wells varying in
+thickness from 5 SrO planes down to a single, atomically thin SrO plane. At the
+polar-nonpolar SmTO/STO interface, an electrostatic discontinuity leads to
+approximately half an electron per areal unit cell transferred from the
+interfacial SmO layer into the neighboring STO quantum well. We observe this
+charge transfer as a suppression of the t$_{2g}$ absorption peaks that
+minimizes contrast with the neighboring SmTO layers at those energies and leads
+to a pronounced absence of superlattice peaks in the reflectivity data. Our
+results demonstrate the sensitivity of RXR to electronic reconstruction at the
+atomic scale, and establish RXR as a powerful means of characterizing charge
+transfer at buried oxide interfaces.",1806.05733v1
+2018-07-09,Thermal Stability Study of Transition Metal Perovskite Sulfides,"Transition metal perovskite chalcogenides, a class of materials with rich
+tunability in functionalities, are gaining increased attention as candidate
+materials for renewable energy applications. Perovskite oxides are considered
+excellent n-type thermoelectric materials. Compared to oxide counterparts, we
+expect the chalcogenides to possess more favorable thermoelectric properties
+such as lower lattice thermal conductivity and smaller band gap, making them
+promising material candidates for high temperature thermoelectrics. Thus, it is
+necessary to study the thermal properties of these materials in detail,
+especially thermal stability, to evaluate their potential. In this work, we
+report the synthesis and thermal stability study of five compounds,
+\alpha-SrZrS$_3$, \beta-SrZrS$_3$, BaZrS$_3$, Ba$_2$ZrS$_4$, and
+Ba$_3$Zr$_2$S$_7$. These materials cover several structural types including
+distorted perovskite, needle-like, and Ruddlesden-Popper phases. Differential
+scanning calorimeter and thermo-gravimetric analysis measurements were
+performed up to 1200{\deg}C in air. Structural and chemical characterizations
+such as X-ray diffraction, Raman spectroscopy, and energy dispersive analytical
+X-ray spectroscopy were performed on all the samples before and after the heat
+treatment to understand the oxidation process. Our studies show that perovskite
+chalcogenides possess excellent thermal stability in air at least up to
+600{\deg}C.",1807.03355v1
+2018-07-10,Optimizing hot electron harvesting at planar metal-semiconductor interfaces with titanium oxynitride thin films,"Understanding metal-semiconductor interfaces is critical to the advancement
+of photocatalysis and sub-bandgap solar energy harvesting where sub-bandgap
+photons can be excited and extracted into the semiconductor. In this work, we
+compare the electron extraction efficiency across Au/TiO2 and titanium
+oxynitride/TiO2-x interfaces, where in the latter case the spontaneously
+forming oxide layer (TiO2-x) creates a metal-semiconductor contact.
+Time-resolved pump-probe spectroscopy is used to study the electron
+recombination rates in both cases. Unlike the nanosecond recombination
+lifetimes in Au/TiO2, we find a bottleneck in the electron relaxation in the
+TiON system, which we explain using a trap-mediated recombination model. Using
+this model, we investigate the tunability of the relaxation dynamics with
+oxygen content in the parent film. The optimized film (TiO0.5N0.5) exhibits the
+highest carrier extraction efficiency, slowest trapping and an appreciable hot
+electron population reaching the surface oxide. Our results demonstrate the
+productive role oxygen can play in enhancing electron harvesting and elongating
+electron lifetimes providing an optimized metal-semiconductor interface using
+only the native oxide of titanium oxynitride.",1807.03702v1
+2018-07-10,Influence of particle size and agglomeration in solid oxide fuel cell cathodes using manganite nanoparticles,"In this work we studied the influence of particle size and agglomeration in
+the performance of solid oxide fuel cell cathodes made with nanoparticles of
+La0.8Sr0.2MnO3. We followed two synthesis routes based on the Liquid Mix
+method. In both procedures we introduced additional reagents in order to
+separated the manganite particles. We evaluated cathodic performance by
+Electrochemical Impedance Spectroscopy in symmetrical
+(CATHODE/ELECTROLYTE/CATHODE) cells. Particle size was tuned by the temperature
+used for cathode sintering. Our results show that deagglomeration of the
+particles, serves to improve the cathodes performance. However, the dependence
+of the performance with the size of the particles is not clear, as different
+trends were obtained for each synthesis route. As a common feature, the
+cathodes with the lowest area specific resistance are the ones sintered at the
+largest temperature. This result indicates that an additional factor related
+with the quality of the cathode/electrolyte sintering, is superimposed with the
+influence of particle size, however further work is needed to clarify this
+issue. The enhancement obtained by deagglomeration suggest that the use of this
+kind of methods deserved to be considered to develop high performance
+electrodes for solid oxide fuel cells.",1807.03816v1
+2018-07-11,Insights into the use of polyethylene oxide in energy storage/conversion devices: A critical review,"In this review, latest updates in the poly (ethylene oxide) based
+electrolytes are summarized. The ultimate goal of researchers globally is
+towards the development of free standing solid polymeric separator for energy
+storage devices. This single free standing solid polymeric separator may
+replace the liquid and separator (organic/Inorganic) used in existing
+efficient/smart energy technology. As an example polyethylene oxide (PEO)
+consist of an electron donor rich group which provides coordinating sites to
+the cation for migration. Owing to this exclusive structure PEO exhibits some
+remarkable properties such as; low glass transition temperature, excellent
+flexibility and ability to make complexation with various metal salts which are
+unattainable by another polymer host. Hence, the PEO is the most emerging
+candidate that have been examined or is currently under audition for
+application in energy storage devices. So, this review article first provides
+the detailed study of the PEO properties, characteristic of constituents of the
+polymer electrolyte and suitable approaches for the modification of polymer
+electrolytes. Then, the synthesization and characterizations techniques are
+outlined. The structures, characteristics, and performance during
+charge-discharge of four types of electrolyte/separators which are Liquid,
+Plasticized, and dispersed/intercalated electrolyte are highlighted. The
+suitable ion transport mechanism proposed by researchers in the different
+renowned group have been discussed for better understanding of the ion dynamics
+in such systems.",1808.03699v1
+2018-08-15,Electron Localization Enhances Cation Diffusion in Transition Metal Oxides: An Electronic Trebuchet Effect,"Ion diffusion is a central part of materials physics of fabrication,
+deformation, phase transformation, structure stability and electrochemical
+devices. Conventional theory focuses on the defects that mediate diffusion and
+explains how their populations influenced by oxidation, reduction, irradiation
+and doping can enhance diffusion. However, we have found the same influences
+can also elevate their mobility by orders of magnitude in several prototypical
+transition-metal oxides. First-principles calculation fundamentally connects
+the latter observation to migrating ion's local structure, which is inherently
+soft and has a broken symmetry, making it susceptible to electron or hole
+localization, thereby realizing a lower saddle-point energy. This finding
+resolves an unanswered question in physical ceramics of the past 30 years: why
+cation diffusion against the prediction of classical nonstoichiometric defect
+physics is enhanced in reduced zirconia, ceria and structurally related
+ceramics? It also suggests the saddle-point electron-phonon interaction that
+enables a negative-U state is akin to the counterweight effect that enables a
+trebuchet. This simple picture for the transitional state explains why enhanced
+kinetics mediated by radical-like-ion migration occurs often, especially under
+extreme conditions.",1808.05196v3
+2018-08-23,"Buffer layer-less fabrication of high-mobility transparent oxide semiconductor, La-doped BaSnO3","Transparent oxide semiconductors (TOSs) showing both high visible
+transparency and high electron mobility have attracted great attention towards
+the realization of advanced optoelectronic devices. La-doped BaSnO3 (LBSO) is
+one of the most promising TOSs because its single crystal exhibits a high
+electron mobility. However, in the LBSO films, it is very hard to obtain high
+mobility due to the threading dislocations, which are originated from the
+lattice mismatch between the film and the substrate. Therefore, many
+researchers have tried to improve the mobility by inserting a buffer layer.
+While the buffer layers increased the electron mobilities, this approach leaves
+much to be desired since it involves a two-step film fabrication process and
+the enhanced mobility values are still significantly lower than single crystal
+values. We show herein that the electron mobility of LBSO films can be improved
+without inserting any buffer layers if the films are grown under highly
+oxidative ozone (O3) atmospheres. The O3 environments relaxed the LBSO lattice
+and reduced the formation of Sn2+ states, which are known to suppress the
+electron mobility in LBSO. The resultant O3-LBSO films showed improved mobility
+values up to 115 cm2 V-1 s-1, which is among the highest in LBSO films on
+SrTiO3 substrates and comparable to LBSO films with buffer layers.",1808.07619v1
+2018-12-22,Fingerprint oxygen redox reactions in batteries through high-efficiency mapping of resonant inelastic X-ray scattering (mRIXS),"Realizing reversible reduction-oxidation (Redox) reactions of lattice oxygen
+in batteries is a promising way to improve the energy and power density.
+However, conventional oxygen absorption spectroscopy fails to distinguish the
+critical oxygen chemistry in oxide-based battery electrodes. Therefore,
+high-efficiency full-range mapping of resonant inelastic X-ray scattering
+(mRIXS) has been developed as a reliable probe of oxygen redox reactions. Here,
+based on mRIXS results collected from a series of Li1.17Ni0.21Co0.08Mn0.54O2
+electrodes at different electrochemical states and its comparison with
+peroxides, we provide a comprehensive analysis of five components observed in
+the mRIXS results. While almost all the components change upon electrochemical
+cycling, comparison with peroxide species show that only two evolving features
+correspond to the critical oxidized oxygen states. One is a specific feature at
+531.0eV excitation and 523.7eV emission energy, the other is a low-energy loss
+feature. We show that both features evolve with electrochemical cycling of
+Li1.17Ni0.21Co0.08Mn0.54O2 electrodes, and could be used for characterizing
+oxygen redox states in battery electrodes. This work is the first benchmark for
+a complete assignment of all the important mRIXS features collected from
+battery materials, which provides guidelines for future studies in
+characterization, analysis and theoretical calculation for probing and
+understanding oxygen redox reactions.",1812.09591v1
+2018-12-25,Smoothed particle hydrodynamics study of friction of the coarse-grained $α$-Al2O3/$α$-Al2O3 and $α$-Fe2O3/$α$-Fe2O3 contacts in behavior of the spring interfacial potential,"The paper uses the spring potential to present interaction between the
+coarse-grained interfacial particles of the $\alpha$-Al2O3/$\alpha$-Al2O3 and
+$\alpha$-Fe2O3/$\alpha$-Fe2O3 contacts in the sliding friction study of these
+micron-scale oxides by smoothed particle hydrodynamics simulations. The spring
+constants of the potential for the particle systems are converted from those of
+the atomic oxide systems that are yielded by the second order polynomial fits
+of the probed surface potentials in molecular dynamics simulations, and are
+dependent on the particle coarse-graining. It is founded that at micron-scale
+the friction properties of the oxides are almost independent of the
+coarse-graining and are the same in the different sliding directions. Even the
+hardness contacts friction coefficient shows a decrease with increasing
+intensity of normal component of the interfacial interaction, originating from
+stability of friction force and growth of normal force. This result is as an
+implementation for the previous observations of sliding friction of various
+materials that showed that a drop of friction coefficient with increasing
+externally applied normal load has originated from deformation of interfaces or
+occurrence of debris at contact, indicating an unsteady contact.",1812.10051v2
+2018-12-26,Lattice-mismatched semiconductor heterostructures,"Semiconductor heterostructure is a critical building block for modern
+semiconductor devices. However, forming semiconductor heterostructures of
+lattice-mismatch has been a great challenge for several decades. Epitaxial
+growth is infeasible to form abrupt heterostructures with large
+lattice-mismatch while mechanical-thermal bonding results in a high density of
+interface defects and therefore severely limits device applications. Here we
+show an ultra-thin oxide-interfaced approach for the successful formation of
+lattice-mismatched semiconductor heterostructures. Following the depiction of a
+theory on the role of interface oxide in forming the heterostructures, we
+describe experimental demonstrations of Ge/Si (diamond lattices), Si/GaAs (zinc
+blende lattice), GaAs/GaN (hexagon lattice), and Si/GaN heterostructures.
+Extraordinary electrical performances in terms of ideality factor, current
+on/off ratio, and reverse breakdown voltage are measured from p-n diodes
+fabricated from the four types of heterostructures, significantly outperforming
+diodes derived from other methods. Our demonstrations indicate the versatility
+of the ultra-thin-oxide-interface approach in forming lattice-mismatched
+heterostructures, open up a much larger possibility for material combinations
+for heterostructures, and pave the way toward broader applications in
+electronic and optoelectronic realms.",1812.10225v1
+2018-12-27,Critical current density of hole doped high-Tc cuprates and heavy fermion superconductors: relevance to the possible quantum critical behavior,"The superconducting critical current density, Jc, in hole doped cuprates show
+strong dependence on the doped hole content, p, within the copper oxide
+plane(s). The doping dependent Jc mainly exhibits the variation of the
+intrinsic depairing critical current density as p is varied. Jc(p) tends to
+peak at p ~ 0.185 in copper oxide superconductors. This particular value of the
+hole content, often termed as the critical hole concentration, has several
+features putative to a quantum critical point (QCP). Very recently, pressure
+dependences of the superconducting transition temperature (Tc) and the critical
+current (Ic) in pure CeRhIn5 and Sn doped CeRhIn5 heavy fermion compounds have
+been reported (Nature Communications (2018) 9:44, DOI:
+10.1038/s41467-018-02899-5). The critical pressure demarcates an
+antiferromagnetic quantum critical point where both Tc and Ic are maximized. We
+have compared and contrasted this behavior with those found for
+Y1-xCaxBa2Cu3O7-d in this brief communication. The resemblance of the
+systematic behavior of the critical current with pressure and hole content
+between heavy fermion systems and hole doped cuprates is significant. This adds
+to the circumstantial evidence that quantum critical physics probably plays a
+notable role beyond the unconventional normal and superconducting state
+properties of copper oxide superconductors.",1812.10632v1
+2018-12-29,Electronic structure and transport in amorphous metal oxide and amorphous metal oxy-nitride semiconductors,"Recently amorphous oxide semiconductors (AOS) have gained commercial interest
+due to their low-temperature processability, high mobility and areal uniformity
+for display backplanes and other large area applications. A multi-cation
+amorphous oxide (a-IGZO) has been researched extensively and is now being used
+in commercial applications. It is proposed in the literature that overlapping
+In-5s orbitals form the conduction path and the carrier mobility is limited due
+to the presence of multiple cations which create a potential barrier for the
+electronic transport in a-IGZO semiconductors. A multi-anion approach towards
+amorphous semiconductors has been suggested to overcome this limitation and has
+been shown to achieve hall mobilities up to an order of magnitude higher
+compared to multi-cation amorphous semiconductors. In the present work, we
+compare the electronic structure and electronic transport in a multi-cation
+amorphous semiconductor, a-IGZO and a multi-anion amorphous semiconductor,
+a-ZnON using computational methods. Our results show that in a-IGZO, the
+carrier transport path is through the overlap of outer s-orbitals of mixed
+cations and in a-ZnON, the transport path is formed by the overlap of Zn-4s
+orbitals, which is the only type of metal cation present. We also show that for
+multi-component ionic amorphous semiconductors, electron transport can be
+explained in terms of orbital overlap integral which can be calculated from
+structural information and has a direct correlation with the carrier effective
+mass which is calculated using computationally expensive first principle DFT
+methods.",1812.11333v3
+2019-01-15,Diluted Oxide Interfaces with Tunable Ground States,"The metallic interface between two oxide insulators, such as LaAlO3/SrTiO3
+(LAO/STO), provides new opportunities for electronics and spintronics. However,
+due to the presence of multiple orbital populations, tailoring the interfacial
+properties such as the ground state and metal-insulator transitions remains
+challenging. Here, we report an unforeseen tunability of the phase diagram of
+LAO/STO by alloying LAO with a ferromagnetic LaMnO3 insulator without forming
+lattice disorder and at the same time without changing the polarity of the
+system. By increasing the Mn-doping level, x, of LaAl1-xMnxO3/STO, the
+interface undergoes a Lifshitz transition at x = 0.225 across a critical
+carrier density of nc= 2.8E13 cm-2, where a peak TSC =255 mK of superconducting
+transition temperature is observed. Moreover, the LaAl1-xMnxO3 turns
+ferromagnetic at x >=0.25. Remarkably, at x = 0.3, where the metallic interface
+is populated by only dxy electrons and just before it becomes insulating, we
+achieve reproducibly a same device with both signatures of superconductivity
+and clear anomalous Hall effect. This provides a unique and effective way to
+tailor oxide interfaces for designing on-demand electronic and spintronic
+devices.",1901.04776v1
+2019-03-03,Oxide: The Essence of Rust,"Rust claims to advance industrial programming by bridging the gap between
+low-level systems programming and high-level application programming. At the
+heart of the argument that this enables programmers to build more reliable and
+efficient software is the borrow checker - a novel approach to ownership that
+aims to balance type system expressivity with usability. And yet, to date there
+is no core type system that captures Rust's notion of ownership and borrowing,
+and hence no foundation for research on Rust to build upon.
+  In this work, we set out to capture the essence of this model of ownership by
+developing a type systems account of Rust's borrow checker. We present Oxide, a
+formalized programming language close to source-level Rust (but with
+fully-annotated types). This presentation takes a new view of lifetimes as an
+approximation of the provenances of references, and our type system is able to
+automatically compute this information through a substructural typing judgment.
+We provide the first syntactic proof of type safety for borrow checking using
+progress and preservation. Oxide is a simpler formulation of borrow checking -
+including recent features such as non-lexical lifetimes - that we hope
+researchers will be able to use as the basis for work on Rust.",1903.00982v4
+2019-03-13,Combined in situ microstructural study of the relationships between local grain boundary structure and passivation on microcrystalline copper,"In situ Electro-Chemical Scanning Tunneling Microscopy (ECSTM) and Electron
+Back-Scatter Diffraction analysis of the same local microstructural region were
+combined to study the relationships between grain boundary (GB) type and
+structure and passivation on microcrystalline copper in 0.1 M NaOH aqueous
+solution. The results show that, for high angle random boundaries, passivation
+in the Cu(I) oxidation range is characterized by a decrease of the depth of GB
+edge region due to the formation of a passive film locally thicker than on the
+adjacent grains and thus to anodic oxidation being locally less efficient since
+it consumes more copper at the grain boundaries. For sigma3 CSL boundaries, the
+Cu(I) passivation efficiency was observed to be dependent on the local
+structure of the boundaries. A transition from more to less efficient
+passivation was observed for a deviation angle of 0.4-0.5{\deg} of the {111} GB
+plane with respect to the perfect geometry of an ideal coherent twin boundary.
+This transition would result from the effect on the local anodic oxidation
+properties of an increased density of misfit dislocations accommodating the
+increased deviation of the boundary plane from the exact CSL plane.",1903.05371v1
+2019-04-16,The role of Ce$^{3+}$/Ce$^{4+}$ in the spectroscopic properties of cerium oxide doped zinc-tellurite glasses prepared under air,"Emerging technologies are demanding innovative properties of glasses. In this
+work, Cerium Oxide is used as a dopant in Zinc-Tellurite samples and its
+effects on the properties of the glass are investigated. Thermal analysis and
+x-ray diffraction confirmed the amorphous nature of all samples. The bivalent
+nature of Cerium is investigated spectroscopically and a strong redshift
+induced by the dopant is attributed to charge transfers
+O$^{2-}{\rightarrow}$Ce$^{4+}$, while the 4f-5d transition of Ce$^{3+}$ could
+not be identified in absorption or luminescence measurements. Yellow/red
+(570/650 nm) emission under 405/450 nm pumping were observed and are originated
+from Te$^{4+}$ ions, which absorbs light in the UV/blue region of the spectrum.
+The incorporation of some Cerium Oxide enhanced the visible luminescence,
+though we found no evidence that Cerium ions play some role in the radiative
+process. The luminescence is enhanced though due changes in the glass network
+induced by the dopant.",1904.07622v6
+2019-08-06,FeOOH instability at the lower mantle conditions,"Goethite, {\alpha}-FeOOH, is a major component among oxidized iron species,
+called rust, which formed as a product of metabolism of anoxygenic prokaryotes
+(1, 2) inhabiting the Earth from about 3.8 billion years (Gy) ago until the
+Great Oxidation Event (GOE) of about 2.5 Gy ago. The rust was buried on the
+ocean floor (1, 2) and had to submerge into the Earth mantle with subducting
+slabs due to the plate tectonics started about 2.8 Gy ago (3). The fate and the
+geological role of the rust at the lower mantle high-pressure and
+high-temperature(HPHT) conditions is unknown. We studied the behavior of
+goethite up to 82(2) GPa and 2300(100) K using in situ synchrotron
+single-crystal X-ray diffraction. At these conditions, corresponding to the
+coldest slabs at the depth of about 1000 km, {\alpha}-FeOOH decomposes to
+various iron oxides (Fe2O3, Fe5O7, Fe7O10, Fe6.32O9) and an oxygen-rich fluid.
+Our results suggest that recycling of the rust in the Earth mantle could
+contribute to oxygen release to the atmosphere and explain the sporadic
+increase of the oxygen level before the GOE linked to the formation of Large
+Igneous Provinces(4).",1908.02114v1
+2019-08-08,Atomically-Smooth Single-Crystalline VO$_2$ thin films with Bulk-like Metal-Insulator Transitions,"Atomically-abrupt interfaces in transition metal oxide (TMO) heterostructures
+could host a variety of exotic condensed matter phases that may not be found in
+the bulk materials at equilibrium. A critical step in the development of such
+atomically-sharp interfaces is the deposition of atomically-smooth TMO thin
+films. Optimized deposition conditions exist for the growth of perovskite
+oxides. However, the deposition of rutile oxides, such as VO$_2$, with
+atomic-layer precision has been challenging. In this work, we used pulsed laser
+deposition (PLD) to grow atomically-smooth VO$_2$ thin films on rutile TiO$_2$
+(101) substrates. We show that optimal substrate preparation procedure followed
+by the deposition of VO$_2$ films at a temperature conducive for step-flow
+growth mode is essential for achieving atomically-smooth VO$_2$ films. The
+films deposited at optimal substrate temperatures show a step and terrace
+structure of the underlying TiO$_2$ substrate. At lower deposition
+temperatures, there is a transition to a mixed growth mode comprising of island
+growth and layer-by-layer growth modes. VO$_2$ films deposited at optimal
+substrate temperatures undergo a metal to insulator transition at a transition
+temperature of $\sim$325 K with $\sim$10$^3$ times increase in resistance, akin
+to MIT in bulk VO$_2$.",1908.02937v1
+2019-08-20,Factors limiting ferroelectric field-effect doping in complex-oxide heterostructures,"Ferroelectric field-effect doping has emerged as a powerful approach to
+manipulate the ground state of correlated oxides, opening the door to a new
+class of field-effect devices. However, this potential is not fully exploited
+so far, since the size of the field-effect doping is generally much smaller
+than expected. Here we study the limiting factors through magneto-transport,
+scanning transmission electron and piezo-response force microscopy in
+ferroelectric/superconductor (YBa2Cu3O7-{\delta} /BiFeO3) heterostructures, a
+model system showing very strong field-effects. Still, we find that they are
+limited in the first place by an incomplete ferroelectric switching. This can
+be explained by the existence of a preferential polarization direction set by
+the atomic terminations at the interface. More importantly, we also find that
+the field-effect carrier doping is accompanied by a strong modulation of the
+carrier mobility. Besides making quantification of field-effects via Hall
+measurements not straightforward, this finding suggests that ferroelectric
+poling produces structural changes (e.g. charged defects or structural
+distortions) in the correlated oxide channel. Those findings have important
+consequences for the understanding of ferroelectric field-effects and for the
+strategies to further enhance them.",1908.07365v1
+2019-08-22,Photoexcited Small Polaron Formation in Goethite (α-FeOOH) Nanorods Probed by Transient Extreme Ultraviolet Spectroscopy,"Small polaron formation limits the mobility and lifetimes of photoexcited
+carriers in metal oxides. As the ligand field strength increases, the carrier
+mobility decreases, but the effect on the photoexcited small polaron formation
+is still unknown. Extreme ultraviolet transient absorption spectroscopy is
+employed to measure small polaron formation rates and probabilities in goethite
+({\alpha}-FeOOH) crystalline nanorods at pump photon energies from 2.2 to 3.1
+eV. The measured polaron formation time increases with excitation photon energy
+from 70 {\pm} 10 fs at 2.2 eV to 350 {\pm} 30 fs at 2.6 eV, whereas the polaron
+formation probability (85 {\pm} 10%) remains constant. By comparison to
+hematite ({\alpha}-Fe2O3), an oxide analog, the role of ligand composition and
+metal center density in small polaron formation time is discussed. This work
+suggests that incorporating small changes in ligands and crystal structure
+could enable the control of photoexcited small polaron formation in metal
+oxides.",1908.08591v1
+2019-08-23,On the emergence of conductivity at SrTiO3-based oxide interfaces -- an in-situ study,"Heterostructures and crystal interfaces play a major role in state-of-the-art
+semiconductor devices and play a central role in the field of oxide
+electronics. In oxides the link between the microscopic properties of the
+interfaces and bulk properties of the resulting heterostructures challenge our
+fundamental understanding. Insights on the early growth stage of interfaces and
+its influence on resulting physical properties are scarce -- typically the
+information is inferred from post growth characterization. Here, we report on
+real time measurements of the transport properties of SrTiO3-based
+heterostructures while the crystal heterostructure is forming. Surprisingly, we
+detect a conducting interface already at the initial growth stage, much earlier
+than the well-established critical thickness limit for observing conductivity
+ex-situ after sample growth. We investigate how the conductivity depends on
+various physical processes occurring during pulsed laser depositions, including
+light illumination, particle bombardment by the plasma plume, interactions with
+the atmosphere and oxygen migration from SrTiO3 to the thin films of varying
+compositions. Using this approach, we propose a new design tool to control the
+electrical properties of interfaces in real time during their formation.",1908.09011v1
+2019-08-29,Gate-tunable Rashba spin-orbit coupling and spin polarization at diluted oxide interfaces,"Diluted oxide interface of LaAl1-xMnxO/SrTiO3 (LAMO/STO) provides a new way
+of tuning the ground states of the interface between the two band insulators of
+LAO and STO from metallic/superconducting to highly insulating. Increasing the
+Mn doping level (x) leads to a delicate control of the carrier density as well
+as a raise in the electron mobility and spin polarization. Herein, we
+demonstrate a tunable Rashba spin-orbit coupling (SOC) and spin polarization of
+LAMO/STO (0.2 <= x <= 0.3) by applying a back gate. The presence of SOC causes
+the splitting of energy band into two branches by a spin splitting energy. The
+maximum spin splitting energy depends on the Mn doping and decreases with the
+increasing Mn content and then vanishes at x = 0.3. The carrier density
+dependence of the spin splitting energy for different compositions shows a
+dome-shaped behavior with a maximum at different normalized carrier density.
+These findings have not yet been observed in LAO/STO interfaces. A fully
+back-gate-tunable spin-polarized 2DEL is observed at the interface with x = 0.3
+where only dxy orbits are populated (5.3E12 cm-2 <= ns <= 1.0E13 cm-2). The
+present results shed light on unexplored territory in SOC at STO-base oxide
+heterostructures and make LAMO/STO an intriguing platform for spin-related
+phenomena in 3d-electron systems.",1908.11167v1
+2019-11-08,Chloride-induced alterations of the passive film on 316L stainless steel and blocking effect of pre-passivation,"Electrochemical polarization measurements were combined with surface analysis
+by Time of Flight Secondary Ion Mass Spectroscopy (ToF-SIMS), X-Ray
+Photoelectron Spectroscopy (XPS) and Atomic Force Microscopy (AFM) to study the
+alterations of the passive film on 316L austenitic stainless steel induced by
+the presence of chlorides in sulfuric acid electrolyte. The work was performed
+at a stage of initiation of localized corrosion preceding metastable pitting at
+the micrometer scale as verified by current transient analysis and AFM. The
+results show that Cl-ions enter the bilayer structure of the surface oxide
+already formed in the native oxide-covered initial surface state at
+concentrations below the detection limit of XPS (< 0.5 at%), mostly in the
+hydroxide outer layer where Fe(III) and Mo(IV,VI) species are concentrated but
+barely in the oxide inner layer enriched in Cr(III). Their main effect is to
+produce a less resistive passive state by poisoning dehydroxylation and further
+Cr(III) and Mo(IV,VI) enrichments obtained in the absence of chlorides. This
+detrimental effect can be suppressed by pre-passivation in a Cl-free
+electrolyte, which blocks the entry of chlorides in the passive film, including
+in the outer exchange layer, and enables the beneficial aging-induced
+variations of the composition to take place despite the presence of chlorides
+in the environment.",1911.03244v1
+2019-11-11,Mechanical properties of VMoNO as a function of oxygen concentration: toward development of hard and tough refractory oxynitrides,"Improved toughness is a central goal in the development of wear-resistant
+refractory ceramic coatings. Extensive theoretical and experimental research
+has revealed that NaCl structure VMoN alloys exhibit surprisingly high
+ductility combined with high hardness and toughness. However, during operation,
+protective coatings inevitably oxidize, a problem which may compromise material
+properties and performance. Here, we explore the role of oxidation in altering
+VMoN properties. Density functional theory and theoretical intrinsic hardness
+models are used to investigate the mechanical behavior of cubic V0.5Mo0.5N1-xOx
+solid solutions as a function of the oxygen concentration x. Elastic-constant
+and intrinsic hardness calculations show that oxidation does not degrade the
+mechanical properties of V0.5Mo0.5N. Electronic structure analyses indicate
+that the presence of oxygen reduces the covalent bond character, which slightly
+lowers the alloy strength and intrinsic hardness. Nevertheless, the character
+of metallic d-d states, which are crucial for allowing plastic deformation and
+enhancing toughness, remains unaffected. Overall, our results suggest that
+VMoNO oxynitrides, with oxygen concentrations as high as 50%, possess high
+intrinsic hardness, while still being ductile.",1911.04165v1
+2019-11-13,A carbon-nanofiber glass composite with high electrical conductivity,"The use of oxide glasses is pervasive throughout everyday amenities and
+commodities. Such glasses are typically electrical insulators, and endowing
+them with electrical conductivity without changing their salutary mechanical
+properties, weight, or thermoformability enables new applications in
+multifunctional utensils, smart windows, and automotive parts. Previous
+strategies to impart electrical conductivity include modifying the glass
+composition or forming a solid-in-solid composite of the glass and a conductive
+phase. Here we demonstrate using the latter strategy the highest reported
+room-temperature electrical conductivity in a bulk oxide glass 1800 S/m
+corresponding to the theoretical limit for the loading fraction of the
+conductive phase. This is achieved through glass-sintering of a mixture of
+carbon nanofibers and oxide flint F2 or soda lime glasses, with the bulk
+conductivity further enhanced by a polyethylene-block-poly(ethylene glycol)
+additive. A theoretical model provides predictions that are in excellent
+agreement with the dependence of conductivity of these composites on the
+carbon-loading fraction. Moreover, nanoscale electrical characterization of the
+composite samples provides evidence for the existence of a connected network of
+carbon nanofibers throughout the bulk. Our results establish a potentially
+low-cost approach for producing large volumes of highly conductive glass
+independently of the glass composition.",1911.05273v1
+2019-11-20,High electrical conducting deep-ultraviolet-transparent oxide semiconductor La-doped SrSnO3 exceeding ~3000 S cm-1,"La-doped SrSnO3 (LSSO) is known as one of deep-ultraviolet (DUV)-transparent
+conducting oxides with an energy bandgap of ~4.6 eV. Since LSSO can be grown
+heteroepitaxially on more wide bandgap substrates such as MgO (Eg ~7.8 eV),
+LSSO is considered to be a good candidate as a DUV-transparent electrode.
+However, the electrical conductivity of LSSO films are below 1000 S cm^-1, most
+likely due to the low solubility of La ion in the LSSO lattice. Here we report
+that high electrically conducting (>3000 S cm^-1) LSSO thin films with an
+energy bandgap of ~4.6 eV can be fabricated by pulsed laser deposition on MgO
+substrate followed by a simple annealing in vacuum. From the X-ray diffraction
+and the scanning transmission electron microscopy analyses, we found that
+lateral grain growth occurred during the annealing, which improved the
+activation rate of La ion, leading to a significant improvement of carrier
+concentration (3.26 x 10^20 cm^-3) and Hall mobility (55.8 cm^2 V^-1 s^-1). The
+present DUV-transparent oxide semiconductor would be useful as a transparent
+electrode for developing optoelectronic devices, which transmit and/or emit
+DUV-light.",1911.08818v1
+2019-12-26,From High-Entropy Ceramics to Compositionally-Complex Ceramics: A Case Study of Fluorite Oxides,"Using fluorite oxides as an example, this study broadens high-entropy
+ceramics (HECs) to compositionally-complex ceramics (CCCs) or multi-principal
+cation ceramics (MPCCs) to include medium-entropy and/or non-equimolar
+compositions. Nine compositions of compositionally-complex fluorite oxides
+(CCFOs) with the general formula of (Hf1/3Zr1/3Ce1/3)1-x(Y1/2X1/2)xO2-delta (X
+= Yb, Ca, and Gd; x = 0.4, 0.148, and 0.058) are fabricated. The phase
+stability, mechanical properties, and thermal conductivities are measured.
+Compared with yttria-stabilized zirconia, these CCFOs exhibit increased cubic
+phase stability and reduced thermal conductivity, while retaining high Young's
+modulus (~210 GPa) and nanohardness (~18 GPa). Moreover, the
+temperature-dependent thermal conductivity in the non-equimolar CCFOs shows an
+amorphous-like behavior. In comparison with their equimolar high-entropy
+counterparts, the medium-entropy non-equimolar CCFOs exhibit even lower thermal
+conductivity (k) while maintaining high modulus (E), thereby achieving higher
+E/k ratios. These results suggest a new direction to achieve
+thermally-insulative yet stiff CCCs (MPCCs) via exploring non-equimolar and/or
+medium-entropy compositions.",1912.11742v2
+2020-03-06,Direct evidence for low-energy electron emission following O LVV Auger transitions at oxide surfaces,"Oxygen, the third most abundant element in the universe, plays a key role in
+the chemistry of condensed matter and biological systems. Here, we report
+evidence for a hitherto unexplored Auger transition in oxides, where a valence
+band electron fills a vacancy in the 2s state of oxygen, transferring
+sufficient energy to allow electron emission. We used a beam of positrons with
+kinetic energies of $\sim$1 eV to create O 2s holes via matter-antimatter
+annihilation. This made possible the elimination of the large secondary
+electron background that has precluded definitive measurements of the
+low-energy electrons emitted through this process. Our experiments indicate
+that low-energy electron emission following the Auger decay of O 2s holes from
+adsorbed oxygen and oxide surfaces are very efficient. Specifically, our
+results indicate that the low energy electron emission following the Auger
+decay of O 2s hole is nearly as efficient as electron emission following the
+relaxation of O 1s holes in TiO$_2$. This has important implications for the
+understanding of Auger-stimulated ion desorption, Coulombic decay, photodynamic
+cancer therapies, and may yield important insights into the radiation-induced
+reactive sites for corrosion and catalysis.",2003.02975v2
+2020-03-06,Dynamical Transitions of Supercooled Water in Graphene oxide Nanopores: Influence of Surface Hydrophobicity,"Molecular dynamics simulations are carried out to explore the dynamical
+crossover phenomenon in strongly confined and mildly supercooled water in
+graphene oxide nanopores. In contrast to studies where confinement is used to
+study the properties of bulk water, we are interested in the dynamical
+transitions for strongly confined water in the absence of any bulk-like water.
+The influence of the physicochemical nature of the graphene oxide surface on
+the dynamical transitions is investigated by varying the extent of
+hydrophobicity on the confining surfaces placed at an inter-surface separation
+of 10 \AA\,. All dynamical quantities show a typical slowing down as the
+temperature is lowered from 298 to 200 K; however, the nature of the transition
+is a distinct function of the surface type. Water confined between surfaces
+consisting of alternating hydrophilic and hydrophobic regions exhibit a
+strong-to-strong dynamical transition in the diffusion coefficients and
+rotational relaxation times at a crossover temperature of 237 K and show a
+fragile-to-strong transition in the $\alpha$-relaxation time at 238 K. The
+observed crossover temperature is much higher than the freezing point of the
+SPC/E water model used in this study, indicating that these dynamical
+transitions can occur with mild supercooling under strong confinement in the
+absence of bulk-like water. In contrast, water confined in hydrophilic pore
+shows a single Arrhenius energy barrier over the entire temperature range. Our
+results indicate that in addition to confinement, the nature of the surface can
+play a critical role in determining the dynamical transitions for water upon
+supercooling.",2003.03163v1
+2020-03-11,The pseudoatomic orbital basis: electronic accuracy and soft-mode distortions in ABO$_3$ perovskites,"The perovskite oxides are known to be susceptible to structural distortions
+over a long wavelength when compared to their parent cubic structures. From an
+ab initio simulation perspective, this requires accurate calculations including
+many thousands of atoms; a task well beyond the remit of traditional plane
+wave-based density functional theory (DFT). We suggest that this void can be
+filled using the methodology implemented in the large-scale DFT code, CONQUEST,
+using a local pseudoatomic orbital (PAO) basis. Whilst this basis has been
+tested before for some structural and energetic properties, none have treated
+the most fundamental quantity to the theory, the charge density $n(\mathbf{r})$
+itself. An accurate description of $n(\mathbf{r})$ is vital to the perovskite
+oxides due to the crucial role played by short-range restoring forces
+(characterised by bond covalency) and long range coulomb forces as suggested by
+the soft-mode theory of Cochran and Anderson. We find that modestly sized basis
+sets of PAOs can reproduce the plane-wave charge density to a total integrated
+error of better than 0.5% and provide Bader partitioned ionic charges, volumes
+and average charge densities to similar degree of accuracy. Further, the
+multi-mode antiferroelectric distortion of PbZrO$_3$ and its associated
+energetics are reproduced by better than 99% when compared to plane-waves. This
+work suggests that electronic structure calculations using efficient and
+compact basis sets of pseudoatomic orbitals can achieve the same accuracy as
+high cutoff energy plane-wave calculations. When paired with the CONQUEST code,
+calculations with high electronic and structural accuracy can now be performed
+on many thousands of atoms, even on systems as delicate as the perovskite
+oxides.",2003.05327v1
+2020-03-31,Electrochromism in Electrolyte-Free and Solution Processed Bragg Stacks,"Achieving an active manipulation of colours has huge implications in
+optoelectronics, as colours engineering can be exploited in a number of
+applications, ranging from display to lightning. In the last decade, the
+synergy of the highly pure colours of 1D photonic crystals, also known as Bragg
+stacks, with electro-tunable materials have been proposed as an interesting
+route to attain such a technologically relevant effect. However, recent works
+rely on the use of liquid electrolytes, which can pose issues in terms of
+chemical and environmental stability. Here, we report on the proof-of-concept
+of an electrolyte free and solution-processed electrochromic Bragg stack. We
+integrate an electro-responsive plasmonic metal oxide, namely indium tin oxide,
+in a 1D photonic crystal structure made of alternating layers of ITO and TiO2
+nanoparticles. In such a device we observed 15 nm blue-shift upon application
+of an external bias (5 V), an effect that we attribute to the increase of ITO
+charge density arising from the capacitive charging at the metal
+oxide/dielectric interface and from the current flowing throughout the porous
+structure. Our data suggest that electrochromism can be attained in all-solid
+state systems by combining a judicious selection of the constituent materials
+with device architecture optimisation.",2003.14050v1
+2020-05-18,Inversion-symmetry engineering in sub-unit-cell-layered oxide thin films,"Inversion symmetry breaking is a ubiquitous concept in condensed-matter
+science. On the one hand, it is a prerequisite for many technologically
+relevant effects such as piezoelectricity, photovoltaic and nonlinear optical
+properties and spin-transport phenomena. On the other hand, it may determine
+abstract properties such as the electronic topology in quantum materials.
+Therefore, the creation of materials where inversion symmetry can be turned on
+or off by design may be the ultimate route towards controlling parity-related
+phenomena and functionalities. Here, we engineer the symmetry of ultrathin
+epitaxial oxide films by sub-unit-cell growth control. We reversibly activate
+and deactivate inversion symmetry in the layered hexagonal manganites,
+h-RMnO$_3$ with R = Y, Er, Tb. While an odd number of half-unit-cell layers
+exhibits a breaking of inversion symmetry through its arrangement of MnO$_5$
+bipyramids, an even number of such half-unit-cell layers takes on a
+centrosymmetric structure. Here we control the resulting symmetry by tracking
+the growth in situ via optical second-harmonic generation. We furthermore
+demonstrate that our symmetry engineering works independent of the choice of R
+and even in heterostructures mixing constituents with different R in a
+two-dimensional growth mode. Symmetry engineering on the atomic level thus
+suggests a new platform for the controlled activation and deactivation of
+symmetry-governed functionalities in oxide-electronic epitaxial thin films.",2005.09083v1
+2020-06-03,The oxygen partial pressure in solid oxide electrolysis cells with two layer electrolytes,"A number of degradation mechanisms have been observed during the long-term
+operation of solid oxide electrolysis cells (SOEC). Using an electrolyte charge
+carrier transport model, we quantify the oxygen potentials across the
+electrolyte and thereby provide insights into these degradation mechanisms. Our
+model describes the transport of charge carriers in the electrolyte when the
+oxygen partial pressure is extremely low by accounting for the spatial
+variation of the concentration of oxygen vacancies in the electrolyte.
+Moreover, we identify four quantities that characterize the distribution of
+oxygen partial pressure in the electrolyte, which are directly related to the
+degradation mechanisms in the electrolyte as well: the two oxygen partial
+pressures at the interfaces of the electrodes and the electrolyte, the oxygen
+partial pressure at the interface of YSZ/GDC, and the position of the abrupt
+change in oxygen potential near the p-n junction that develops in YSZ when one
+side of the cell is exposed to fuel (low oxygen potential, n-type conduction)
+and the other side is exposed to oxidant (high oxygen potential, p-type
+conduction). We give analytical estimates for all of these quantities. These
+analytical expressions provide guidance on the parameters that need to be
+controlled to suppress the degradation observed in the electrolyte. In
+addition, the effects of operating conditions, particularly current density and
+operating temperature, on degradation are discussed.",2006.02523v1
+2020-06-10,Chemical-Grafting of Graphene Oxide Quantum Dots for Enhanced Electrochemical Analysis of Aromatics,"Because of high surface area and combination of various functional groups,
+graphene oxide (GO) is currently one of the most actively studying materials
+for electroanalytical applications. Self-supported GO is not practical enough
+to be utilized individually and thus is commonly integrated with different
+supporting carriers. Having large lateral size GO can only wrap the particles
+of the support and thus, can significantly reduce the surface area of porous
+materials. To reach synergy form high surface area and polyfunctional nature of
+GO, and a rigid structure of porous support, the lateral size of GO must be
+essentially decreased. Recently reported graphene oxide quantum dots (GOQDs)
+can fulfill this task. We report successful preparation of mesoporous silica
+supported GOQDs exhibiting strong luminescent band with the maximum at 404 nm.
+From N2 adsorption isotherms, it was demonstrated that the surface area of the
+resulted hybrid material was augmented. Raman spectrum of SiO2-GOQDs shows two
+distinct peaks at 1585 cm-1(G-peak) and 1372 cm-1 (D-peak) indicating presence
+ordered basal plane of graphene with aromatic sp2 domains, and disordered
+oxygen-containing structure. Covalent immobilization of GOQDs on aminosilica
+via such oxygen-containing fragments was proved by FTIR, MAS 13C MNR, and XPS
+spectroscopy. SiO2-GOQDs was used as a modifier of carbon paste electrode for
+differential pulse voltammetry determination of four environmental:
+sulfamethoxazole, trimethoprim, diethylstilbestrol (DES), and estriol (EST).
+The modified electrodes demonstrated an essential decrease in LOD for EST
+(220%) and DES (760%), which was explained by significant pi-pi stacking
+interaction between GOQDs and aromatic system of the analytes.",2006.05634v1
+2020-06-19,Earth and Mars -- distinct inner Solar System products,"Composition of terrestrial planets records planetary accretion, core-mantle
+and crust-mantle differentiation, and surface processes. Here we compare the
+compositional models of Earth and Mars to reveal their characteristics and
+formation processes. Earth and Mars are equally enriched in refractory elements
+(1.9 $\times$ CI), although Earth is more volatile-depleted and less oxidized
+than Mars. Their chemical compositions were established by nebular
+fractionation, with negligible contributions from post-accretionary losses of
+moderately volatile elements. The degree of planetary volatile element
+depletion might correlate with the abundances of chondrules in the accreted
+materials, planetary size, and their accretion timescale, which provides
+insights into composition and origin of Mercury, Venus, the Moon-forming giant
+impactor, and the proto-Earth. During its formation before and after the
+nebular disk's lifetime, the Earth likely accreted more chondrules and less
+matrix-like materials than Mars and chondritic asteroids, establishing its
+marked volatile depletion. A giant impact of an oxidized, differentiated
+Mars-like (i.e., composition and mass) body into a volatile-depleted, reduced
+proto-Earth produced a Moon-forming debris ring with mostly a proto-Earth's
+mantle composition. Chalcophile and some siderophile elements in the silicate
+Earth added by the Mars-like impactor were extracted into the core by a sulfide
+melt. In contrast, the composition of Mars indicates its rapid accretion of
+lesser amounts of chondrules under nearly uniform oxidizing conditions. Mars'
+rapid cooling and early loss of its dynamo likely led to the absence of plate
+tectonics and surface water, and the present-day low surface heat flux. These
+similarities and differences between the Earth and Mars made the former
+habitable and the other inhospitable to uninhabitable.",2006.11051v2
+2020-06-28,Effective Reduction of Oxygen Debris in Graphene Oxide,"Graphene oxide (GO) raised substantial interest in the last two decades
+thanks to its unique properties beyond those of pristine graphene, including
+electronic energy band-gap, hydrophilic behavior and numerous anchoring sites
+required for functionalization. In addition, GO was found to be a cheap
+mass-production source for the formation of the pristine graphene. However, the
+presence of numerous clusters containing oxygen functional groups (called
+debris) on the GO surface hinders the GO integration in electronic devices.
+Here, we present a simple method aimed to reduce the density of oxygen debris
+weakly bonded to the surface. The method consists of minimal treatments, like
+sonication and/or water rinsing processes. Whereas this simple method removed
+epoxy and hydroxyl oxygen groups weakly attached to the graphene matrix, the
+double C=O bonds are almost not affected by the applied treatment, as
+demonstrated by X-ray photoelectron spectroscopy and Fourier transform infrared
+spectroscopy. Scanning tunneling microscopy and high-resolution transmission
+electron microscopy measures designated non-uniform distribution of the
+oxidation sites, appearing as clusters concentrated preferentially on GO
+defected regions, albeit separated by pristine graphene areas. The results
+should have an impact in the implementation of GO in electronic devices
+deposited on different substrates.",2006.15668v2
+2020-09-02,Understanding modes of negative differential resistance in amorphous and polycrystalline vanadium oxides,"Metal-oxide-metal devices based on amorphous VOx are shown to exhibit one of
+two distinct negative differential resistance (NDR) characteristics depending
+on the maximum current employed for electroforming. For low compliance currents
+they exhibit a smooth S-type characteristic and have a temperature-dependent
+device resistance characterised by an activation energy of 0.25 eV, consistent
+with conduction in polycrystalline VO2, while for high-compliance currents they
+exhibit an abrupt snap-back characteristic and a resistance characterised by an
+activation energy of 0.025 eV, consistent with conduction in oxygen deficient
+VOx. In both cases, the temperature dependence of the switching voltage implies
+that the conductivity change is due to the insulator-metal transition in VO2.
+From this analysis it is concluded that electroforming at low currents creates
+a conductive filament comprised largely of polycrystalline VO2, while
+electroforming at high currents creates a composite structure comprised of VO2
+and a conductive halo of oxygen deficient VOx. The effect of electroforming on
+the NDR mode is then explained with reference to a lumped element model of
+filamentary conduction that includes the effect of a parallel resistance
+created by the halo. These results provide new insight into the NDR response of
+vanadium-oxide-based devices and a basis for designing devices with specific
+characteristics.",2009.00810v1
+2020-09-03,Doped graphene oxide functionalization strategy for synthesis of nanocomposite membranes: electrospun coatings in biomedical field application,"An electrospun membrane for vascular stent coating made of
+2-methacryloyloxyethyl phosphorylcholine and butyl methacrylate copolymer
+(MPC-co-BMA), also known as (PMB), reinforced with functionalized and nitrogen
+doped reduced graphene oxide (f-NrGO) is presented. This membrane due to the
+nitrogen doped reduced graphene oxide (NrGO) negative electric charge has the
+capacity to repeal low density lipoproteins (LDL), which under specific
+conditions are the main cause of atherosclerotic disease. The NrGO
+functionalization process is detailed, as it creates strong bonds between NrGO
+and PMB, avoiding NrGO sheets to detach from the membrane. The copolymer
+synthesis was characterized by FTIR and chemical bonds between f-NrGO and PMB
+were proved by XPS and HNMR. Additionally, a simplified test bank that
+simulates blood flow conditions demonstrated the NrGO functionalization effect
+over the membrane. For the electrospinning process, optimal parameters were a
+voltage of 14.5 kV, and a flow rate of 0.3 mL/h, which lead to better
+properties of the membrane for the application. DMA results confirmed that the
+best reinforcement percentage of f-NrGO in terms of mechanical properties was
+0.1 wt% and AFM images indicated the presence of the f-NrGO sheets over the
+fibers. Finally, the contact angle revealed the repulsion response to LDL, such
+behavior is promising to applications like cardiovascular coated stents.",2009.01820v1
+2020-10-06,Conductance Model for Single-Crystalline/Compact Metal Oxide Gas Sensing Layers in the Non-Degenerate Limit: Example of Epitaxial SnO$_2$(101),"Semiconducting metal oxide (SMOX)-based gas sensors are indispensable for
+safety and health applications, e.g. explosive, toxic gas alarms, controls for
+intake into car cabins and monitor for industrial processes. In the past, the
+sensor community has been studying polycrystalline materials as sensors where
+the porous and random microstructure of the SMOX does not allow a separation of
+the phenomena involved in the sensing process. This lead to conduction models
+that can model and predict the behavior of the overall response, but they were
+not capable of giving fundamental information regarding the basic mechanisms
+taking place. The study of epitaxial layers is the definite prove to clarify
+the different aspects and contributions of the sensing mechanisms that are not
+possible to do by studying a polycrystalline sample. A detailed analytical
+model for n and p-type single-crystalline/compact metal oxide gas sensors was
+developed that directly relates the conductance of the sample with changes in
+the surface electrostatic potential. Combined DC resistance and work function
+measurements were used in a compact SnO2 (101) layer in operando conditions
+that allowed us to check the validity of our model in the region where
+Boltzmann approximation holds to determine surface and bulk properties of the
+material.",2010.02962v1
+2020-10-19,Nitric Oxide and other molecules: Molecular Modelling and Low FrequencyExploration using the Murchison Widefield Array,"We present new molecular modelling for 14NO and 15NO and a deep, blind
+molecular line survey at low radio frequencies (99-129 MHz). This survey is the
+third in a series completed with the Murchison Widefield Array (MWA), but in
+comparison with the previous surveys, uses four times more data (17 hours vs. 4
+hours) and is three times better in angular resolution (1' vs. 3'). The new
+molecular modelling for nitric oxide and its main isotopologue has seven
+transitions within the MWA frequency band (although we also present the higher
+frequency transitions). Although we did not detect any new molecular lines at a
+limit of 0.21 Jy beam^-1, this work is an important step in understanding the
+data processing challenges for the future Square Kilometre Array (SKA) and
+places solid limits on what is expected in the future of low-frequency surveys.
+The modelling can be utilised for future searches of nitric oxide.",2010.09868v1
+2020-10-28,"Single-Layer Di-titanium oxide Ti2O MOene: Multifunctional Promises for Electride, Anode Materials, and Superconductor","Using the first-principles calculations, we report the existence of the
+single-layer (SL) di-titanium oxide Ti$_2$O (labeled as MOene) that constructs
+a novel family of MXene based on transition metal oxides. This MOene material
+strongly contrasts the conventional ones consisting of transition metal
+carbides and/or nitrides. SL Ti$_2$O has high thermal and dynamical stabilities
+due to the strong Ti$-$O ionic bonding interactions. Moreover, this material is
+an intrinsic electride and exhibits extremely low diffusion barriers of
+$\sim$12.0 and 6.3 meV for Li- and Na diffusion, respectively. When applied as
+anode materials in lithium-ion batteries and sodium-ion batteries, it possesses
+a high energy storage capacity (960.23 mAhg$^{-1}$), surpassing the traditional
+MXenes-based anodes. The superb electrochemical performance stems from the
+existed anionic electron on Ti$_2$O surface. Astonishingly, SL Ti$_{2}$O is
+also determined to be a superconductor with a superconducting transition
+temperature (\textit{T$_{c}$}) of $\sim$9.8 K, which originates from the
+soft-mode of the first acoustic phonon branch and enhanced electron-phonon
+coupling in the low-frequency region. Our finding broadens the family of MXenes
+and would facilitate more experimental efforts toward future nanodevices.",2010.14879v1
+2020-11-19,Marangoni Fingering Instabilities in Oxidizing Liquid Metals,"Eutectic gallium-indium (EGaIn), a room-temperature liquid metal alloy, has
+the largest tension of any liquid at room temperature, and yet can nonetheless
+undergo fingering instabilities. This effect arises because, under an applied
+voltage, oxides deposit on the surface of the metal, which leads to a lowering
+of the interfacial tension, allowing spreading under gravity. Understanding the
+spreading dynamics of room temperature liquid metals is important for
+developing soft electronics and understanding fluid dynamics of liquids with
+extreme surface tensions. When the applied voltage or the oxidation rate
+becomes too high, the EGaIn undergoes fingering instabilities, including
+tip-splitting, which occur due to a Marangoni stress on the interface. Our
+experiments are performed with EGaIn droplets placed in an electrolyte (sodium
+hydroxide); by placing the EGaIn on copper electrodes, which EGaIn readily
+wets, we are able to control the initial width of EGaIn fingers, setting the
+initial conditions of the spreading. Two transitions are observed: (1) a
+minimum current density at which all fingers become unstable to narrower
+fingers; (2) a current density at which the wider fingers undergo a single
+splitting event into two narrower fingers. We present a phase diagram as a
+function of current density and initial finger width, and identify the minimum
+width below which the single tip-splitting does not occur.",2011.10016v1
+2020-11-23,Bottom Contact Metal Oxide Interface Modification Improving the Efficiency of Organic Light Emitting Diodes,"The performance of solution-processed organic light emitting diodes (OLEDs)
+is often limited by non-uniform contacts. In this work, we introduce
+Ni-containing solution-processed metal oxide (MO) interfacial layers inserted
+between indium tin oxide (ITO) and
+poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) to improve
+the bottom electrode contact for OLEDs using the poly(p-phenylene vinylene)
+(PPV) derivative Super-Yellow (SY) as an emission layer. For ITO/Ni-containing
+MO/PEDOT:PSS bottom electrode structures we show enhanced wetting properties
+that result in an improved OLED device efficiency. Best performance is achieved
+using a Cu-Li co-doped spinel nickel cobaltite [(Cu-Li):NiCo2O4], for which the
+current efficiency and luminous efficacy of SY OLEDs increased, respectively,
+by 12% and 11% from the values obtained for standard devices without a
+Ni-containing MO interface modification between ITO and PEDOT:PSS. The enhanced
+performance was attributed to the improved morphology of PEDOT:PSS, which
+consequently increased the hole injection capability of the optimized
+ITO/(Cu-Li):NiCo2O4/PEDOT:PSS electrode.",2011.11445v1
+2021-02-04,Resolving the History of Life on Earth by Seeking Life As We Know It on Mars,"An origin of Earth life on Mars would resolve significant inconsistencies
+between the inferred history of life and Earth's geologic history. Life as we
+know it utilizes amino acids, nucleic acids, and lipids for the metabolic,
+informational, and compartment-forming subsystems of a cell. Such building
+blocks may have formed simultaneously from cyanosulfidic chemical precursors in
+a planetary surface scenario involving ultraviolet light, wet-dry cycling, and
+volcanism. However, early Earth was a water world, and the timing of the rise
+of oxygen on Earth is inconsistent with final fixation of the genetic code in
+response to oxidative stress. A cyanosulfidic origin of life could have taken
+place on Mars via photoredox chemistry, facilitated by orders of magnitude more
+sub-aerial crust than early Earth, and an earlier transition to oxidative
+conditions. Meteoritic bombardment may have generated transient habitable
+environments and ejected and transferred life to Earth. The Mars 2020
+Perseverance Rover offers an unprecedented opportunity to confirm or refute
+evidence consistent with a cyanosulfidic origin of life on Mars, search for
+evidence of ancient life, and constrain the evolution of Mars' oxidation state
+over time. We should seek to prove or refute a Martian origin for life on Earth
+alongside other possibilities.",2102.02362v1
+2021-02-04,Interfacial Tension Modulation of Liquid Metal via Electrochemical Oxidation,"This progress report summarizes recent studies of electrochemical oxidation
+to modulate the interfacial tension of gallium-based alloys. These alloys,
+which are liquid at ambient conditions, have the largest interfacial tension of
+any liquid at room temperature. The ability to modulate the tension offers the
+possibility to create forces that change the shape and position of the metal.
+It has been known since the late 1800s that electrocapillarity-the use of
+potential to modulate the electric double layer on the surface of metals in
+electrolyte-lowers the interfacial tension of liquid metal. Yet, this
+phenomenon can only achieve modest changes in interfacial tension since it is
+limited to potential windows that avoid reactions. A recent discovery suggests
+that reactions driven by the electrochemical oxidation of gallium alloys cause
+the interfacial tension to decrease from ~500 mN/m at 0 V to ~0 mN/m at ~0.8 V,
+a change in tension that goes well beyond what is possible via conventional
+electrocapillarity or surfactants. The changes in tension are reversible;
+reductive potentials return the metal back to a state of high interfacial
+tension. This report aims to summarize key work and introduce beginners to this
+field by including electrochemistry basics while addressing misconceptions. We
+discuss applications that utilize modulations in interfacial tension of liquid
+metal and conclude with remaining opportunities and challenges that need
+further investigation.",2102.02383v1
+2021-02-05,Metal/SrTiO$_3$ two-dimensional electron gases for spin-to-charge conversion,"SrTiO$_3$-based two-dimensional electron gases (2DEGs) can be formed through
+the deposition of epitaxial oxides like LaAlO$_3$ or of reactive metals such as
+Al. Such 2DEGs possess a finite Rashba spin-orbit coupling that has recently
+been harnessed to interconvert charge and spin currents through the direct and
+inverse Edelstein and spin Hall effects. Here we compare the formation and
+properties of 2DEGs generated in SrTiO$_3$ by the growth of Al, Ta and Y
+ultrathin films by magnetron sputtering. By combining in situ and ex situ X-ray
+photoelectron spectroscopy (XPS) we gain insight into the reduction of the
+SrTiO$_3$ and the appearance of Ti$^{3+}$ states associated with 2DEG
+formation, its reoxidation by exposure to the air, and the transformation of
+the metal into its binary oxides. We extract the carrier densities through
+magnetotransport and compare them with the XPS data. Finally, working with
+samples covered by an extra layer of NiFe, we perform spin-pumping
+ferromagnetic resonance experiments and investigate spin-charge conversion as a
+function of gate voltage. We identify trends in the data across the different
+sample systems and discuss them as a function of the carrier density and the
+transparency of the metal oxide tunnel barrier.",2102.03093v1
+2021-02-09,Direct Observation and Control of Surface Termination in Perovskite Oxide Heterostructures,"The interfacial behavior of quantum materials leads to emergent phenomena
+such as two dimensional electron gases, quantum phase transitions, and
+metastable functional phases. Probes for in situ and real time surface
+sensitive characterization are critical for active monitoring and control of
+epitaxial synthesis, and hence the atomic-scale engineering of heterostructures
+and superlattices. Termination switching, especially as an interfacial process
+in ternary complex oxides, has been studied using a variety of probes, often ex
+situ; however, direct observation of this phenomena is lacking. To address this
+need, we establish in situ and real time reflection high energy electron
+diffraction and Auger electron spectroscopy for pulsed laser deposition, which
+provide structural and compositional information of the surface during film
+deposition. Using this unique capability, we show, for the first time, the
+direct observation and control of surface termination in complex oxide
+heterostructures of SrTiO3 and SrRuO3. Density-functional-theory calculations
+capture the energetics and stability of the observed structures and elucidate
+their electronic behavior. This demonstration opens up a novel approach to
+monitor and control the composition of materials at the atomic scale to enable
+next-generation heterostructures for control over emergent phenomena, as well
+as electronics, photonics, and energy applications.",2102.05022v1
+2021-02-20,Thermal lensing-induced soliton molecules in beta-phase Gallium Oxide,"In recent years, beta gallium oxide (beta-\ce{Ga2O3}) has become the most
+investigated isomorph of gallium oxide polymorphs, due to the great potential
+it represents for applications in optoelectronics and photonics for solar
+technology, particularly in blind ultraviolet photodetector solar cells (SBUV)
+designs. To optimize its use in these applications, and to identify possible
+new features, knowledge of its fundamental properties is relevant. In this
+respect, optical, thermal and electronic properties of beta-\ce{Ga2O3} have
+been studied expriementally, providing evidence of a wide-band inorganic and
+transparent semiconductor with a Kerr nonlinearity. Thermo-optical properties
+of the material, probed in SBUV sensing experiments, have highlighted a sizable
+heat diffusion characterized by a temperature gradient along the path of
+optical beams, quadratic in beam position and promoting a refractive-index
+change with temperature. The experimentally observed Kerr nonlinearity together
+with the thermally induced birefringence, point unambiguously to a possible
+formation of soliton molecules during propagation of high-intensity fields in
+beta-\ce{Ga2O3}. To put this conjecture on a firm ground we propose a
+theoretical analysis, based on the cubic nonlinear Schroedinger equation in 1+1
+spatial dimension, in which thermal lensing creates an effective potential
+quadratic in the coordinate of beam position. Using the non-isospectral
+inverse-scattering transform method, the exact one-soliton solution to the
+propagation equation is obtained. This solution features a bound state of
+entangled pulses forming a soliton molecule, in which pulses are more or less
+entangled depending on characteristic parameters of the system.",2102.10418v2
+2021-02-23,Insight into the structure-property relation of UO2 nanoparticles,"Highly crystalline UO2 nanoparticles (NPs) with sizes of 2-3 nm were produced
+by fast chemical deposition of uranium(IV) under reducing conditions at pH
+8-11. The particles were then characterized by microscopic and spectroscopic
+techniques including high-resolution transmission electron microscopy (HRTEM),
+X-ray diffraction (XRD), high-energy resolution fluorescence detection (HERFD)
+X-ray absorption spectroscopy at the U M4 edge and extended X-ray absorption
+fine structure (EXAFS) spectroscopy at the U L3 edge. The results of this
+investigation show that despite U(IV) being the dominant oxidation state of the
+freshly prepared UO2 NPs, they oxidize to U4O9 with time and under the X-ray
+beam, indicating the high reactivity of U(IV) under these conditions. Moreover,
+it was found that the oxidation process of NPs is accompanied by their growth
+in size to 6 nm. We highlight here the major differences and similarities of
+the UO2 NPs properties with PuO2, ThO2 and CeO2 NPs.",2102.11643v1
+2021-02-25,Metal-Oxide Sensor Array for Selective Gas Detection in Mixtures,"We present a monolithic, microfabricated, metal-oxide semiconductor (MOS)
+sensor array in conjunction with a machine learning algorithm to determine
+unique fingerprints of individual gases within homogenous mixtures. The array
+comprises four different metal oxides, and is engineered for independent
+temperature control and readout from each individual pixel in a multiplexed
+fashion. The sensor pixels are designed on a very thin membrane to minimize
+heat dissipation, thereby significantly lowering the overall power consumption
+($<$30 $\mu$W average power). The high dimensional data obtained by running the
+pixels at different temperatures, is used to train our machine learning
+algorithm with an average accuracy $\sim$ 88$\%$ for high resolution detection
+and estimation of concentration of individual constituents in a homogenous
+mixture. While the response of MOS sensors to various gases has been
+demonstrated, very few studies have investigated the response of these sensors
+to homogeneous mixtures of gases comprising several gases. We demonstrate this
+principle for a binary homogeneous mixture of ozone and carbon monoxide, both
+of which are criteria pollutant gases. Our findings indicate that a
+multiplicity of MOS elements together with the ability to vary and measure at
+various temperatures are essential in predicting concentration of individual
+gases within mixtures, thereby overcoming a key limitation of MOS sensors -
+poor selectivity. The small form-factor and microfabrication approach of our
+sensor array also lends itself to CMOS integration paving the way for a
+platform for wearable and portable applications.",2102.12990v1
+2021-02-26,Ion implantation in \b{eta}-Ga2O3: physics and technology,"Gallium oxide and in particular its thermodynamically stable \b{eta}-Ga2O3
+phase is within the most exciting materials in research and technology nowadays
+due to its unique properties, such as an ultra-wide band gap and a very high
+breakdown electric field, finding a number of applications in electronics and
+optoelectronics. Ion implantation is a traditional technological method used in
+these fields, and its well-known advantages can contribute greatly to the rapid
+development of physics and technology of Ga2O3-based materials and devices.
+Here, the current status of ion beam implantation in \b{eta}-Ga2O3 is reviewed.
+The main attention is paid to the results of experimental study of damage under
+ion irradiation and the properties of Ga2O3 layers doped by ion implantation.
+The results of ab initio theoretical calculations of the impurities and defects
+parameters are briefly presented, and the physical principles of a number of
+analytical methods used to study implanted gallium oxide layers are
+highlighted. The use of ion implantation in the development of such Ga2O3-based
+devices as metal oxide field effect transistors, Schottky barrier diodes, and
+solar-blind UV detectors, is described together with systematical analysis of
+the achieved values of their characteristics. Finally, the most important
+challenges to be overcome in this field of science and technology are
+discussed.",2102.13439v1
+2021-02-28,Tuning the Reactivity of Nanoenergetic Gas Generators Based on Bismuth and Iodine oxidizers,"There is a growing interest on novel energetic materials called Nanoenergetic
+Gas-Generators (NGGs) which are potential alternatives to traditional energetic
+materials including pyrotechnics, propellants, primers and solid rocket fuels.
+NGGs are formulations that utilize metal powders as a fuel and oxides or
+hydroxides as oxidizers that can rapidly release large amount of heat and
+gaseous products to generate shock waves. The heat and pressure discharge,
+impact sensitivity, long term stability and other critical properties depend on
+the particle size and shape, as well as assembling procedure and intermixing
+degree between the components. The extremely high energy density and the
+ability to tune the dynamic properties of the energetic system makes NGGs ideal
+candidates to dilute or replace traditional energetic materials for emerging
+applications. In terms of energy density, performance and controllability of
+dynamic properties, the energetic materials based on bismuth and iodine
+compounds are exceptional among the NGGs. The thermodynamic calculations and
+experimental study confirm that NGGs based on iodine and bismuth compounds
+mixed with aluminum nanoparticles are the most powerful formulations to date
+and can be used potentially in microthrusters technology with high
+thrust-to-weight ratio with controlled combustion and exhaust velocity for
+space applications. The resulting nano thermites generated significant value of
+pressure discharge up to 14.8 kPa m3/g. They can also be integrated with carbon
+nanotubes to form laminar composite yarns with high power actuation of up to
+4700 W/kg, or be used in other emerging applications such as biocidal agents to
+effectively destroy harmful bacteria in seconds, with 22 mg/m2 minimal content
+over infected area.",2103.00614v1
+2021-03-03,Dimensional Control of Octahedral Tilt in SrRuO3 via Infinite-layered Oxides,"Manipulation of octahedral distortion at atomic length scale is an effective
+means to tune the physical ground states of functional oxides. Previous work
+demonstrates that epitaxial strain and film thickness are variable parameters
+to modify the octahedral rotation and tilt. However, selective control of
+bonding geometry by structural propagation from adjacent layers is rarely
+studied. Here we propose a new route to tune the ferromagnetic response in
+SrRuO3 (SRO) ultrathin layers by oxygen coordination of adjacent SrCuO2 (SCO)
+layers. The infinite-layered CuO2 in SCO exhibits a structural transformation
+from ""planar-type"" to ""chain-type"" as reducing film thickness. These two
+orientations dramatically modify the polyhedral connectivity at the interface,
+thus altering the octahedral distortion of SRO. The local structural variation
+changes the spin state of Ru and hybridization strength between Ru 4d and O 2p
+orbitals, leading to a significant change in the magnetoresistance and
+anomalous Hall resistivity of SRO layers. These findings could launch further
+investigations into adaptive control of magnetoelectric properties in quantum
+oxide heterostructures using oxygen coordination.",2103.02101v1
+2021-04-01,Band-Order Anomaly at the γ-Al2O3/SrTiO3 Interface Drives the Electron-Mobility Boost,"Rich functionalities of transition-metal oxides and their interfaces bear an
+enormous technological potential. Its realization in practical devices
+requires, however, a significant improvement of yet relatively low electron
+mobility in oxide materials. Recently, a mobility boost of about two orders of
+magnitude has been demonstrated at the spinel/perovskite {\gamma}-Al2O3/SrTiO3
+interface compared to the paradigm perovskite/perovskite LaAlO3/SrTiO3. We
+explore the fundamental physics behind this phenomenon from direct measurements
+of the momentum-resolved electronic structure of this interface using resonant
+soft-X-ray angle-resolved photoemission. We find an anomaly in orbital ordering
+of the mobile electrons in {\gamma}-Al2O3/SrTiO3 which depopulates electron
+states in the top STO layer. This rearrangement of the mobile electron system
+pushes the electron density away from the interface that reduces its overlap
+with the interfacial defects and weakens the electron-phonon interaction, both
+effects contributing to the mobility boost. A crystal-field analysis shows that
+the band order alters owing to the symmetry breaking between the spinel
+{\gamma}-Al2O3 and perovskite SrTiO3. The band-order engineering exploiting the
+fundamental symmetry properties emerges as another route to boost the
+performance of oxide devices.",2104.00498v1
+2021-05-20,Competition of superconductivity and charge density wave in selective oxidized CsV3Sb5 thin flakes,"The recently discovered layered kagome metals AV$_3$Sb$_5$ (A = K, Rb, and
+Cs) with vanadium kagome networks provide a novel platform to explore
+correlated quantum states intertwined with topological band structures. Here we
+report the prominent effect of hole doping on both superconductivity and charge
+density wave (CDW) order, achieved by selective oxidation of exfoliated thin
+flakes. A superconducting dome is revealed as a function of the effective
+doping content. The superconducting transition temperature ($T_{\mathrm{c}}$)
+and upper critical field in thin flakes are significantly enhanced compared
+with the bulk, which is accompanied by the suppression of CDW. Our detailed
+analyses establish the pivotal role of van Hove singularities (VHSs) in
+promoting correlated quantum orders in these kagome metals. Our experiment not
+only demonstrates the intriguing nature of superconducting and CDW orders, but
+also provides a novel route to tune the carrier concentration through both
+selective oxidation and electric gating. This establishes AV$_3$Sb$_5$ as a
+tunable 2D platform for the further exploration of topology and correlation
+among 3$d$ electrons in kagome lattices.",2105.09898v4
+2021-05-27,Route to High-Performance Micro-solid Oxide Fuel Cells on Metallic Substrates,"Micro-solid oxide fuel cells based on thin films have strong potential for
+use in portable power devices. However, devices based on silicon substrates
+typically involve thin-film metallic electrodes which are unstable at high
+temperatures. Devices based on bulk metal substrates overcome these
+limitations, though performance is hindered by the challenge of growing
+state-of-the-art epitaxial materials on metals. Here, we demonstrate for the
+first time the growth of epitaxial cathode materials on metal substrates
+(stainless steel) commercially supplied with epitaxial electrolyte layers (1.5
+{um (Y2O3)0.15(ZrO2)0.85 (YSZ) + 50 nm CeO2). We create epitaxial mesoporous
+cathodes of (La0.60Sr0.40)0.95Co0.20Fe0.80O3 (LSCF) on the substrate by growing
+LSCF/MgO vertically aligned nanocomposite films by pulsed laser deposition,
+followed by selectively etching out the MgO. To enable valid comparison with
+the literature, the cathodes are also grown on single-crystal substrates,
+confirming state-of-the-art performance with an area specific resistance of
+100ohmegacm2 at 500dC and activation energy down to 0.97 eV. The work marks an
+important step toward the commercialization of high-performance micro-solid
+oxide fuel cells for portable power applications.",2105.13117v1
+2021-08-10,The Ionization Energies of Dust-Forming Metal Oxide Clusters,"Stellar dust grains are predominantly composed of mineralic, anorganic
+material forming in the circumstellar envelopes of oxygen-rich AGB stars.
+However, the initial stage of the dust synthesis, or its nucleation, is not
+well understood. In particular, the chemical nature of the nucleating species,
+represented by molecular clusters, is uncertain. We investigated the vertical
+and adiabatic ionization energies of four different metal-oxide clusters by
+means of density functional theory. They included clusters of magnesia
+(MgO)$_n$, silicon monoxide (SiO)$_n$, alumina (Al$_2$O$_3$)$_n$, and titania
+(TiO$_2$)$_n$ with stoichiometric sizes of $n$=1$-$8. The magnesia, alumina,
+and titania clusters showed relatively little variation in their ionization
+energies with respect to the cluster size n: 7.1$-$8.2 eV for (MgO)$_n$,
+8.9$-$10.0 eV for (Al$_2$O$_3$)$_n$, and 9.3$-$10.5 eV for (TiO$_2$)$_n$. In
+contrast, the (SiO)$_n$ ionization energies decrease with size $n$, starting
+from 11.5 eV for $n$=1, and decreasing to 6.6 eV for $n$=8. Therefore, we set
+constraints on the stability limit for neutral metal-oxide clusters to persist
+ionization through radiation or high temperatures and for the nucleation to
+proceed via neutral-neutral reactions.",2108.04618v1
+2021-08-19,Electrochromism of Ni-deficient nickel oxide -- Theoretical justification,"The development of new electrochromic materials and devices, like smart
+windows, has an enormous impact on the energy efficiency of modern society. One
+of the crucial materials in this technology is nickel-oxide. Ni-deficient NiO
+shows anodic electrochromism whose mechanism is still under debate. Using DFT+U
+calculations, we show that Ni vacancy generation results in the formation of
+hole polarons localised at the two oxygens next to the vacancy. Upon Li
+insertion or injection of an extra electron into Ni-deficient NiO, one hole
+gets filled, and the hole bipolaron is converted into a hole polaron
+well-localized at one O atom. Furthermore, the calculated absorption
+coefficients demonstrate that Li insertion/extraction or rather the
+addition/removal of an extra electron into Ni-deficient NiO can lead to
+switching between the oxidized (colored) and the reduced (bleached) states.
+Hence, our results suggest a new mechanism of Ni-deficient NiO electrochromism
+not related to the Ni2+/Ni3+ transition but based on the formation and
+annihilation of hole polarons in oxygen p-states.",2108.08578v1
+2021-08-25,Synthesis of a High-Capacity α-Fe2O3@C Conversion Anode and a High-Voltage LiNi0.5Mn1.5O4 Spinel Cathode and Their Combination in a Li-Ion Battery,"A Li-conversion alpha-Fe2O3@C nanocomposite anode and a high-voltage
+LiNi0.5Mn1.5O4 cathode are synthesized in parallel, characterized, and combined
+in a Li-ion battery. alpha-Fe2O3@C is prepared via annealing of maghemite iron
+oxide and sucrose under an argon atmosphere and subsequent oxidation in air.
+The nanocomposite exhibits a satisfactory electrochemical response in a lithium
+half-cell, delivering almost 900 mA h g-1, as well as a significantly longer
+cycle life and higher rate capability compared to the bare iron oxide
+precursor. The LiNi0.5Mn1.5O4 cathode, achieved using a modified
+co-precipitation approach, reveals a well-defined spinel structure without
+impurities, a sub-micrometrical morphology, and a reversible capacity of ca.
+120 mA h g-1 in a lithium half-cell with an operating voltage of 4.8 V. Hence,
+a lithium-ion battery is assembled by coupling the alpha-Fe2O3@C anode with the
+LiNi0.5Mn1.5O4 cathode. This cell operates at about 3.2 V, delivering a stable
+capacity of 110 mA h g-1 (referred to the cathode mass) with a Coulombic
+efficiency exceeding 97%. Therefore, this cell is suggested as a promising
+energy storage system with expected low economic and environmental impacts.",2108.11314v1
+2021-09-09,Self-sealing complex oxide resonators,"Although 2D materials hold great potential for next-generation pressure
+sensors, recent studies revealed that gases permeate along the membrane-surface
+interface that is only weakly bound by van der Waals interactions,
+necessitating additional sealing procedures. In this work, we demonstrate the
+use of free-standing complex oxides as self-sealing membranes that allow the
+reference cavity of pressure sensors to be sealed by a simple anneal. To test
+the hermeticity, we study the gas permeation time constants in nano-mechanical
+resonators made from SrRuO3 and SrTiO3 membranes suspended over SiO2/Si
+cavities which show an improvement up to 4 orders of magnitude in the
+permeation time constant after annealing the devices for 15 minutes. Similar
+devices fabricated on Si3N4/Si do not show such improvements, suggesting that
+the adhesion increase over SiO2 is mediated by oxygen bonds that are formed at
+the SiO2/complex oxide interface during the self-sealing anneal. We confirm the
+enhancement of adhesion by picosecond ultrasonics measurements which show an
+increase in the interfacial stiffness by 70% after annealing. Since it is
+straigthforward to apply, the presented self-sealing method is thus a promising
+route toward realizing ultrathin hermetic pressure sensors.",2109.03978v1
+2021-09-28,Insights into lithium manganese oxide-water interfaces using machine learning potentials,"Unraveling the atomistic and the electronic structure of solid-liquid
+interfaces is the key to the design of new materials for many important
+applications, from heterogeneous catalysis to battery technology. Density
+functional theory (DFT) calculations can in principle provide a reliable
+description of such interfaces, but the high computational costs severely
+restrict the accessible time and length scales. Here, we report machine
+learning-driven simulations of various interfaces between water and lithium
+manganese oxide (Li$_x$Mn$_2$O$_4$), an important electrode material in lithium
+ion batteries and a catalyst for the oxygen evolution reaction. We employ a
+high-dimensional neural network potential (HDNNP) to compute the energies and
+forces several orders of magnitude faster than DFT without loss in accuracy. In
+addition, a high-dimensional neural network for spin prediction (HDNNS) is
+utilized to analyze the electronic structure of the manganese ions. Combining
+these methods, a series of interfaces is investigated by large-scale molecular
+dynamics. The simulations allow us to gain insights into a variety of
+properties like the dissociation of water molecules, proton transfer processes,
+and hydrogen bonds, as well as the geometric and electronic structure of the
+solid surfaces including the manganese oxidation state distribution,
+Jahn-Teller distortions, and electron hopping.",2109.14068v2
+2021-10-05,Oxide two-dimensional electron gas with high mobility at room-temperature,"The prospect of 2-dimensional electron gases (2DEGs) possessing high mobility
+at room temperature in wide-bandgap perovskite stannates is enticing for oxide
+electronics, particularly to realize transparent and high-electron mobility
+transistors. Nonetheless only a small number of studies to date report 2DEGs in
+BaSnO3-based heterostructures. Here, we report 2DEG formation at the
+LaScO3/BaSnO3 (LSO/BSO) interface with a room-temperature mobility of 60 cm2/V
+s at a carrier concentration of 1.7x1013 cm-2. This is an order of magnitude
+higher mobility at room temperature than achieved in SrTiO3-based 2DEGs. We
+achieved this by combining a thick BSO buffer layer with an ex-situ
+high-temperature treatment, which not only reduces the dislocation density but
+also produces a SnO2-terminated atomically flat surface, followed by the growth
+of an overlying BSO/LSO interface. Using weak-beam dark field imaging and
+in-line electron holography technique, we reveal a reduction of the threading
+dislocation density, and provide direct evidence for the spatial confinement of
+a 2DEG at the BSO/LSO interface. Our work opens a new pathway to explore the
+exciting physics of stannate-based 2DEGs at application-relevant temperatures
+for oxide nanoelectronics.",2110.02305v1
+2021-10-28,Surface Stability of SrNbO$_{3+δ}$ Grown by Hybrid Molecular Beam Epitaxy,"4d transition metal oxides have emerged as promising materials for numerous
+applications including high mobility electronics. SrNbO$_{3}$ is one such
+candidate material, serving as a good donor material in interfacial oxide
+systems and exhibiting high electron mobility in ultrathin films. However, its
+synthesis is challenging due to the metastable nature of the d$^{1}$ Nb$^{4+}$
+cation and the limitations in the delivery of refractory Nb. To date, films
+have been grown primarily by pulsed laser deposition (PLD), but development of
+a means to grow and stabilize the material via molecular beam epitaxy (MBE)
+would enable studies of interfacial phenomena and multilayer structures that
+may be challenging by PLD. To that end, SrNbO$_{3}$ thin films were grown using
+hybrid MBE for the first time using a tris(diethalamido)(tert-butylimido)
+niobium precursor for Nb and an elemental Sr source on GdScO$_{3}$ substrates.
+Varying thicknesses of insulating SrHfO$_{3}$ capping layers were deposited
+using a hafnium tert-butoxide precursor for Hf on top of SrNbO$_{3}$ films to
+preserve the metastable surface. Grown films were transferred in vacuo for
+X-ray photoelectron spectroscopy to quantify elemental composition, density of
+states at the Fermi energy, and Nb oxidation state. Ex situ studies by X-ray
+absorption near edge spectra illustrates the SrHfO$_{3}$ capping plays an
+important role in preserving the Nb 4d$^{1}$ metastable charge state in
+atmospheric conditions.",2110.15341v1
+2021-11-06,Where have all the interstellar silicon carbides gone?,"The detection of the 11.3-micron emission feature characteristic of the Si--C
+stretch in carbon-rich evolved stars reveals that silicon carbide (SiC) dust
+grains are condensed in the outflows of carbon stars. SiC dust could be a
+significant constituent of interstellar dust since it is generally believed
+that carbon stars inject a considerable amount of dust into the interstellar
+medium (ISM). The presence of SiC dust in the ISM is also supported by the
+identification of presolar SiC grains of stellar origin in primitive
+meteorites. However, the 11.3-micron absorption feature of SiC has never been
+seen in the ISM and oxidative destruction of SiC is often invoked. In this work
+we quantitatively explore the destruction of interstellar SiC dust through
+oxidation based on molecular dynamics simulations and density functional theory
+calculations. We find that the reaction of an oxygen atom with SiC molecules
+and clusters is exothermic and could cause CO-loss. Nevertheless, even if this
+is extrapolable to bulk SiC dust, the destruction rate of SiC dust through
+oxidation could still be considerably smaller than the (currently believed)
+injection rate from carbon stars. Therefore, the lack of the 11.3-micron
+absorption feature of SiC dust in the ISM remains a mystery. A possible
+solution may lie in the currently believed stellar injection rate of SiC (which
+may have been overestimated) and/or the size of SiC dust (which may actually be
+considerably smaller than submicron in size).",2111.03920v1
+2021-11-07,"Low-loss tunable infrared plasmons in the high-mobility perovskite (Ba,La)SnO$_3$","BaSnO$_3$ exhibits the highest carrier mobility among perovskite oxides,
+making it ideal for oxide electronics. Collective charge carrier oscillations,
+plasmons, are expected to arise in this material, thus providing a tool to
+control the nanoscale optical field for optoelectronics applications. Here, we
+demonstrate the existence of relatively long-lived plasmons supported by
+high-mobility charge carriers in La-doped BaSnO$_3$ (BLSO). By exploiting the
+high spatial and energy resolution of electron energy-loss spectroscopy with a
+focused beam in a scanning transmission electron microscope, we systematically
+investigate the dispersion, confinement ratio, and damping of infrared
+localized surface plasmons (LSP) in BLSO nanoparticles. We find that the LSPs
+in BLSO are highly spatially confined compared to those sustained by noble
+metals and have relatively low loss and high quality factor compared to other
+doped oxides. Further analysis clarifies the relation between plasmon damping
+and carrier mobility in BLSO. Our results support the use of nanostructured
+degenerate semiconductors for plasmonic applications in the infrared region and
+establish a relevant alternative to more traditional plasmonic materials.",2111.04144v1
+2021-11-28,Investigations on the improved cycling stability of Kazakhstanite phase Fe-V-O layered oxide by using superconcentrated electrolytes: Generalized solubility limit approach (Part I),"In this article, we address the issue of vanadium dissolution pertinent in
+the layered Fe5V15O39(OH)9.9H2O using the solubility limit approach. This
+layered oxide is prepared via a low-cost solution phase synthesis route and
+crystallizes in the Kazakhstanite phase (Space Group: C2/m), confirmed using
+selected area electron diffraction and x-ray diffraction.The layered oxide
+exhibits the 2 electron redox reaction of vanadium (V5+ to V3+) along with the
+1 electron redox reaction of iron within the voltage window of 1.5-3.8V. This
+results in a high specific capacity of ~350mAhg-1 which can be extracted from
+this material. However, the transition from V4+ to V3+ is identified to
+initiate a dissolution process at ~2.5V, resulting in a loss of active material
+and poor cycling stability. The vanadium dissolution is found to be arrested by
+switching to a superconcentrated electrolyte, wherein the amount of 'free'
+solvent is low. An electrolyte, consisting of seven molar lithium
+bis(trifluoromethanesulfonyl)imide in 1,3-Dioxolane: 1,2-Dimethoxyethane = 1:1
+(v:v), is found to be suitable in providing the best cycling stability amongst
+the other compositions tested. The electrochemical characteristics of the
+passivation layers formed over lithium foil are mathematically modeled to
+indicate the preference of superconcentrated electrolytes over relatively
+dilute ones.",2111.14198v1
+2021-11-15,Resistive-nanoindentation on gold: Experiments and modeling of the electrical contact resistance,"This paper reports the experimental, analytical, and numerical study of
+resistive-nanoindentation tests performed on gold samples (bulk and thin film).
+First, the relevant contributions to electrical contact resistance are
+discussed and analytically described. A brief comparison of tests performed on
+gold and on natively oxidized metals highlights the high reproducibility and
+the voltage-independence of experiments on gold(thanks to its oxide-free
+surface). Then, the evolution of contact resistance during nanoindentation is
+fully explained in terms of electronic transport regimes: starting from
+tunneling, electronic transport is then driven by ballistic conduction before
+ending with pure diffusive conduction. The corresponding analytical
+expressions, as well as their validity domains, are determined and compared
+with experimental data,showing excellent agreement. From there, focus is made
+on the diffusive regime. Resistive-nanoindentation outputs are fully described
+by analytical and finite-element modeling. The developed numerical framework
+allows a better understanding of the main parameters: it first assesses the
+technique capabilities (validity domains, sensitivity to tip defect,
+sensitivity to rheology, effect of an oxide layer, and so on), butit also
+validates the different assumptions made on current line distribution. Finally,
+it is shown that a simple calibration procedure allows a well-resolved
+monitoring of the contact area during resistive-nanoindentation performed on
+samples with complex rheologies (ductile thin film on an elastic substrate).
+Comparison to analytical and numerical approaches highlights the strength of
+resistive-nanoindentation for continuous area monitoring.",2111.15474v1
+2021-12-07,Air filtration from sarin/air mixture by porous graphene-oxide membranes: a molecular dynamics study,"Sarin is a very lethal synthetic organophosphorated compound that inhibits
+the nervous system muscle control. Although not used as a chemical weapon
+anymore, it still worries the authorities regarding possible use by terrorists.
+Most of the studies about sarin are theoretical/computational due to its high
+lethality and are concentrated in its detection and degradation. Few studies
+are about air filtration from sarin gas. Here, the potential of graphene
+oxide-based membranes to filter air from sarin/air mixtures is investigated by
+classical molecular dynamics simulations. Membranes formed by one and two
+nanosheets of porous reduced graphene oxide (rGO) were considered. The passage
+of sarin and air molecules through these membranes from a highly concentrated
+region to an empty one, is evaluated as a function of temperature and sarin/air
+relative concentration. Sarin molecules are shown to be trapped by hydroxyl and
+carboxyl chemical groups in the nanosheet, while a considerable passage of air
+molecules (N$_2$, O$_2$ and Ar) through the membranes was verified. The results
+show the capacity of the rGO membranes to retain sarin from passing through,
+even at high temperatures, thus indicating their potential to be used as a
+filter for sarin gas.",2112.03830v2
+2021-12-09,AlCrO protected textured stainless steel surface for high temperature solar selective absorber applications,"The diffusion of substrate material into absorbing layer and oxidation of
+metal substrate or cermet metal nanoparticles at high temperatures are known as
+inevitable problems of the solar selective absorbers. In this study, we
+consider the use of textured stainless steel (SS) surface coated with a
+protective AlCr oxide layer as a high temperature solar selective absorber. The
+textured SS surface was prepared by ion etching techniques and AlCr oxide
+protective layer was deposited by RF magnetron sputtering. The absorptivity and
+emissivity of the as-prepared absorbers were 0.86-0.92 and 0.151-0.168,
+respectively. In order to evaluate the thermal stability, the absorbers were
+annealed at 600-800 C for different time in ambient atmosphere. Absorbers
+demonstrated a red shift of the onset of the reflectivity at all annealing
+temperatures. The high activation energy of 315 kJ/mol was calculated. The
+service lifetime of the absorbers at 500 C was estimated to be about 100 years
+and at 700 and 800 C the absorbers were stable about 50 and 1 hours,
+respectively. A detailed examination of the annealed absorber surface revealed
+growth of surface Mn3O4 nanocrystals, which resulted in observed change of the
+reflectance spectra, while the textured surface morphology had no significant
+change. The results show that the protective textured surface has much higher
+thermal stability in air than iron based cermet absorbers.",2112.04823v1
+2021-12-09,Extending the kinetic and thermodynamic limits of molecular-beam epitaxy utilizing suboxide sources or metal-oxide catalyzed epitaxy,"We observe a catalytic mechanism during the growth of III-O and IV-O
+materials by suboxide molecular-beam epitaxy ($S$-MBE). By supplying the
+molecular catalysts In$_2$O and SnO we increase the growth rates of Ga$_2$O$_3$
+and In$_2$O$_3$. This catalytic action is explained by a metastable adlayer
+$A$, which increases the reaction probability of the reactants Ga$_2$O and
+In$_2$O with active atomic oxygen, leading to an increase of the growth rates
+of Ga$_2$O$_3$ and In$_2$O$_3$. We derive a model for the growth of binary
+III-O and IV-O materials by $S$-MBE and apply these findings to a generalized
+catalytic description for metal-oxide catalyzed epitaxy (MOCATAXY), applicable
+to elemental and molecular catalysts. We derive a mathematical description of
+$S$-MBE and MOCATAXY providing a computational framework to set growth
+parameters in previously inaccessible kinetic and thermodynamic growth regimes
+when using the aforementioned catalysis. Our results indicate MOCATAXY takes
+place with a suboxide catalyst rather than with an elemental catalyst. As a
+result of the growth regimes achieved, we demonstrate a Ga$_2$O$_3$/Al$_2$O$_3$
+heterostructure with unrivaled crystalline quality, paving the way to the
+preparation of oxide device structures with unprecedented perfection.",2112.05022v2
+2021-12-15,Thermal analysis of metal organic precursors for functional Cu doped NiOx hole transporting layer in inverted perovskite solar cells the role of solution combustion chemistry in Cu doped NiOx thin films processing,"Low temperature solution combustion synthesis emerges as a facile method for
+synthesis of functional metal oxides thin films for electronic applications. We
+study the solution combustion synthesis process of Cu:NiOx using different
+molar ratios (w/o, 0.1 and 1.5) of fuel acetylacetone (Acac) to oxidizer (Cu,
+Ni Nitrates) as a function of thermal annealing tempera-tures 150, 200 and 300
+oC. The solution combustion synthesis process, in both thin films and bulk
+Cu:NiOx, is investigated. Thermal analysis studies using TGA and DTA reveal
+that the Cu:NiOx thin films show a more gradual mass loss while the bulk
+Cu:NiOx exhibits a distinct combustion process. The thin films can crystallize
+to Cu:NiOx at annealing temperature of 300 oC irrespective to the Acac/Oxidizer
+ratio whereas lower annealing temperatures (150 and 200 oC) produce amorphous
+materials. A detail characterization study of solution combustion synthesized
+Cu:NiOx including XPS, UV-Vis, AFM and Contact angle measurements is presented.
+Finally, 50 nm Cu:NiOx thin films are introduced as HTLs within the inverted
+perovskite solar cell device architecture. The Cu:NiOx HTL annealed at 150 and
+200 oC provided PVSCs with limited functionality whereas efficient
+triple-cation Cs0.04(MA0.17FA0.83)0.96 Pb(I0.83Br0.17)3 based PVSCs achieved
+for Cu:NiOx HTLs annealed at temperature 300 oC.",2112.08067v1
+2021-12-21,Room-Temperature Valence Transition in a Strain-Tuned Perovskite Oxide,"Cobalt oxides have long been understood to display intriguing phenomena known
+as spin-state crossovers, where the cobalt ion spin changes vs. temperature,
+pressure, etc. A very different situation was recently uncovered in
+praseodymium-containing cobalt oxides, where a first-order coupled
+spin-state/structural/metal-insulator transition occurs, driven by a remarkable
+praseodymium valence transition. Such valence transitions, particularly when
+triggering spin-state and metal-insulator transitions, offer highly appealing
+functionality, but have thus far been confined to cryogenic temperatures in
+bulk materials (e.g., 90 K in Pr1-xCaxCoO3). Here, we show that in thin films
+of the complex perovskite (Pr1-yYy)1-xCaxCoO3-{\delta}, heteroepitaxial strain
+tuning enables stabilization of valence-driven
+spin-state/structural/metal-insulator transitions to at least 291 K, i.e.,
+around room temperature. The technological implications of this result are
+accompanied by fundamental prospects, as complete strain control of the
+electronic ground state is demonstrated, from ferromagnetic metal under tension
+to nonmagnetic insulator under compression, thereby exposing a potential novel
+quantum critical point.",2112.10917v2
+2022-01-28,Substitutional Doped GeSe: Tunable Oxidative States with Strain Engineering,"Layered chalcogenide materials have a wealth of nanoelectronics applications
+like resistive switching and energy-harvesting such as photocatalyst owing to
+rich electronic, orbital, and lattice excitations. In this work, we explore
+monochalcogenide germanium selenide GeSe with respect to substitutional doping
+with 13 metallic cations by using first-principles calculations. Typical
+dopants including s-shell (alkali elements Li and Na), p-shell (Al, Pb and Bi),
+3d (Fe, Cu, Co and Ni), 4d (Pd and Ag) and 5d (Au and Pt) elements are
+systematically examined. Amongst all the cationic dopants, Al with the highest
+oxidation states, implying a high mobility driven by electric field, and
+Al-doped GeSe may be a promising candidate for novel resistive switching
+devices. We show that there exist many localized induced states in the band gap
+of GeSe upon doping Fe, Co, or Ni, while for Cu, Ag, and Au cases there is no
+such states in the gap. The Ag and Cu are + 0.27 and + 0.35 charged
+respectively and the positive charges are beneficial for field-driven motion in
+GeSe. In contrast, Au is slightly negatively charged renders Au-doped GeSe a
+promising photocatalyst and enhanced surface plasmon. Moreover, we explore the
+coexistence of dopant and strain in GeSe and find dynamical adjustments of
+localized states in GeSe with levels successive shifting upward/downward with
+strain. This induces dynamic oxidative states of the dopants under strain which
+should be quite popular in composites where motion of metal adatoms causes
+significant deformation.",2201.11890v1
+2022-03-09,Unusual phase formation in reactively sputtered La-Co-O perovskite thin films,"La-based perovskites are a versatile class of materials that are of interest
+for solid oxide fuel cells and electrocatalytic water splitting. During
+fabrication of composition spread materials libraries of La-Co-based oxide
+systems for the discovery of new catalytic materials, an unusual phase
+formation phenomenon was observed: instead of the expected continuous
+composition gradient, regions with homogeneous composition and single-phase
+structure (La2O3 or stoichiometric La-perovskite) form. This phenomenon occurs
+during reactive co-sputtering and is dependent on O2-flux and substrate
+temperature, investigated from room temperature up to 700 C and is independent
+of the used substrate. It can be described as a self-organized growth, where
+excess transition metal cannot be incorporated into the growing film and the
+forming single-phase regions. It is hypothesized that due to the high
+reactivity of La and the significantly low formation energies of La2O3 and
+La-perovskites, the reactive sputter deposition of La-based oxide films can
+turn, regarding film growth, into a partial CVD-like process which results in
+the unusual self-organized growth of single-phase regions. This phenomenon can
+be leveraged for the exploration of multinary perovskite thin film libraries,
+where the B-site atoms of La-perovskites are systematically substituted.",2203.04631v1
+2022-03-15,Confining Eutectic Gallium Indium (eGaIn) in Expired Artificial Kidneys to Unveil Nanoporous Conductive Wires,"Nanoporous membranes have gained considerable interest in drug delivery1, ion
+transportation2, micro/nanofluidics3, molecular sensing4, and separation
+science5. Artificial kidneys, also known as dialyzers, reject pathogens and
+other unwanted substances from the blood, utilize hundreds of soft and
+nanoporous polymeric microtubes, and slowly become a burden to the environment
+with the growing number of dialysis patients worldwide. We demonstrate the
+fabrication of nanoporous conductive wires utilizing empty polysulfone
+microtubes collected from expired and unused artificial kidneys, also known as
+medical wastes. Injecting a fluidic, highly conductive, and room temperature
+liquid alloy (eutectic gallium indium-eGaIn$_6$, 75% Ga, 25% In) into
+microtubes of a twenty years old dialyzer, here, we have revealed a new class
+of nanoporous and conductive functional materials. These conductive fibers
+upcycle a medical waste, do not require expensive and conventional fabrication
+processes, and still provide the quintessential metal-oxide/metal framework due
+to the presence of the native surface oxide (i.e., Gallium Oxide, Ga2O3) of
+eGaIn at the nanoconfinement (i.e., nanopores) for nano/biosensing. We
+harnessed these new materials to sense and differentiate microliter volumes of
+deionized (DI) water, 1M hydrochloric acid (HCl), and 95% ethanol (EtOH),
+leveraging their electrical signatures. This new class of soft nanomaterials
+has the potential to become the paradigm-shift platforms for the
+next-generation of biomedical, bioelectronics, nanoelectronics, and sensor
+devices.",2203.07744v1
+2022-03-22,Selectivity in Ligand Functionalization of Photocatalytic Metal Oxide Nanoparticles for Phase Transfer and Self-assembly Applications,"Functionalization of photocatalytic metal oxide nanoparticles of TiO2, ZnO,
+WO3 and CuO with amine-terminated (oleylamine) and thiol-terminated
+(1-dodecanethiol) alkyl chained ligands was studied under ambient conditions. A
+high selectivity was observed in the binding specificity of a ligand towards
+nanoparticles of these different oxides. It was observed that oleylamine binds
+stably to only TiO2 and WO3, while 1-dodecanethiol binds stably only to ZnO and
+CuO. Similarly, polar to non-polar solvent phase transfer of TiO2 and WO3
+nanoparticles could be achieved by using oleylamine, but not by
+1-dodecanethiol, while the contrary holds for ZnO and CuO. The surface
+chemistry of ligand functionalized nanoparticles was probed by ATR-FTIR
+spectroscopy, that enabled to elucidate the occupation of the ligands at the
+active sites. The photo-stability of the ligands on the nanoparticle surface
+was determined by the photocatalytic self-cleaning properties of the material.
+While TiO2 and WO3 degrade the ligands within 24 hours under both UV and
+visible light, ligands on ZnO and CuO remain unaffected. The gathered insights
+are also highly relevant from an application point of view. As an example,
+since the ligand functionalized nanoparticles are hydrophobic in nature, they
+can thus be self-assembled at the air-water interface, for obtaining
+nanoparticle films with demonstrated photocatalytic as well as anti-fogging
+properties.",2203.11674v1
+2022-03-27,"Cryopreservation of seeds of blue waterlily (Nymphaea caerulea) using glutathione adding plant vitrification solution, PVS+","Nymphaea caerulea is a valuable freshwater aquatic plant, not only because of
+its ornamental value but also its extractions for chemical and medical uses. It
+is necessary to store its seeds as backup resources. Cryopreservation is the
+reliable, cost-effective method for long-term preservation of botanical genetic
+banks, especially for recalcitrant plants. In this study, we demonstrated that
+due to unable to tolerate desiccation and low-temperature, N. caerulea is
+recalcitrant. Since viability was lost before 6 months storage, N. caerulea
+seeds were not appropriate to long-term store by traditional storage method.
+The only way to long-term store N. caerulea seeds is cryopreservation. However,
+Plant Vitrification Solution 3 (PVS3; 50% w/v sucrose, 50% w/v glycerol), a
+commonly used plant vitrification solution, was ineffective on N. caerulea
+seeds cryopreservation. The maximum survival rate of cryopreserved seeds
+treated by PVS3 was only 23%. Oxidative stress induced by reactive oxygen
+species (ROS) accumulation within seeds was the reason to cause inefficiency of
+PVS3 treated seeds cryopreservation. We developed a new plant vitrification
+solution (PVS+), by adding glutathione (GSH) into PVS3. PVS+ rescued the
+inefficiency by decreasing ROS accumulation and elevated survival rate of
+cryopreserved seeds to 97%. Our results showed some inefficiencies of plant
+tissue cryopreservation may be caused by ROS-induced oxidative stress.
+Antioxidants can reduce ROS-induced oxidative stress and improve seeds survival
+after cryopreservation. In conclusion, N. caerulea seeds were identified as
+recalcitrant and successfully cryopreserved. Suppressing ROS accumulation
+during cryopreservation may be a potential strategy to improve survival rate of
+recalcitrant seeds after cryopreservation.",2203.14201v2
+2022-03-28,In search of the ground state crystal structure of Ta$_2$O$_5$ from ab-initio and Monte Carlo simulations,"Tantalum oxides (Ta$_2$O$_5$) are characterised by attractive physical and
+chemical properties, such as high dielectric constants and anti-reflection
+behaviour. Recently, Ta$_2$O$_5$ nanoparticles have also been proposed as
+possible enhancers of the relative biological effectiveness in hadrontherapy
+for cancer treatment. In principle, their electronic properties can be
+accurately investigated from first-principles simulations. However, the
+existence of several stable polymorphs of these oxides represents a major
+difficulty in order to calculate and disentangle their respective spectral
+features. To assess this problem, we use linear-response time-dependent density
+functional to investigate the energy loss function $\mbox{Im}
+(-1/\bar{\epsilon})$, which is a unique fingerprint of the material, in the
+optical limit for various polymorphs. We show that the experimental reflection
+energy loss signals can be rationalized and interpreted by assuming that the
+$\gamma$-phase of Ta$_2$O$_5$ represents the underlying structural model. We
+notice that both the inclusion of local field effects and spin-orbit coupling
+are crucial to compute the energy loss functions of this material. Finally, to
+further validate the $\gamma$-Ta$_2$O$_5$ polymorph as a model for experimental
+tantalum oxide, we compute the reflection energy loss spectra using a Monte
+Carlo approach, finding an excellent agreement with the experimental data.",2203.15105v1
+2022-04-12,Role of Oxygen Functionalities in Graphene Oxide Architectural Laminate Subnanometer Spacing and Water Transport,"Active research in nanotechnology contemplates the use of nanomaterials for
+engineering applications. However, a primary challenge is understanding the
+effects of nanomaterial properties on industrial device performance and
+translating unique nanoscale properties to the macroscale. One emerging example
+is graphene oxide (GO) membranes for separation processes. Thus, here we
+investigate how individual GO properties can impact layered GO characteristics
+and water permeability. GO chemistry and morphology were controlled with
+easy-to-implement photo-reduction and sonication techniques and were
+quantitatively correlated offering a valuable tool to speed up the
+characterization process. For example, one could perform chemical analysis and
+concurrently obtain morphology information or vice versa. Chemical GO
+modification allows for fine control of GO oxidation state and GO laminate
+nanoarchitecture enabling controlled synthesis of a GO architectural laminate
+(GOAL). The GOAL can be considered as the selective layer of the membrane
+created by interconnected sub-nanometer channels, characterized by a length and
+a height (i.e., GO spacing), through which water molecules permeate. Water
+permeability was measured for eight GOAL characterized by different GO
+chemistry and morphology, and indicate that GO nanochannel height dictates
+water transport. The simulations indicate a no-slip Darcy-like water transport
+regime inside the GOAL due to the presence of basal oxygen functionalities. The
+experimental and simulation evidence presented in this letter help create a
+clearer picture of water transport in GO and can be used to rationally design
+more effective and efficient GO membranes.",2204.06039v1
+2022-04-14,"Role of Polarons in Single-Atom Catalysts: Case Study of Me1 [Au1, Pt1, and Rh1] on TiO2(110)","The local environment of metal-oxide supported single-atom catalysts plays a
+decisive role in the surface reactivity and related catalytic properties. The
+study of such systems is complicated by the presence of point defects on the
+surface, which are often associated with the localization of excess charge in
+the form of polarons. This can affect the stability, the electronic
+configuration, and the local geometry of the adsorbed adatoms. In this work,
+through the use of density functional theory and surface-sensitive experiments,
+we study the adsorption of Rh1, Pt1, and Au1 metals on the reduced TiO2(110)
+surface; a prototypical polaronic material. A systematic analysis of the
+adsorption configurations and oxidation states of the adsorbed metals reveals
+different types of couplings between adsorbates and polarons. As confirmed by
+scanning tunneling microscopy measurements, the favored Pt1 and Au1 adsorption
+at oxygen vacancy sites is associated with a strong electronic charge transfer
+from polaronic states to adatom orbitals, which results in a reduction of the
+adsorbed metal. In contrast, the Rh1 adatoms interact weakly with the excess
+charge, which leaves the polarons largely unaffected. Our results show that an
+accurate understanding of the properties of single-atom catalysts on oxide
+surfaces requires a careful account of the interplay between adatoms, vacancy
+sites, and polarons.",2204.06991v1
+2022-04-19,Ternary Wide Band Gap Oxides for High-Power Electronics Identified Computationally,"As electricity grids become more renewable energy-compliant, there will be a
+need for novel semiconductors that can withstand high power, high voltage, and
+high temperatures. Wide band gap (WBG) semiconductors tend to exhibit large
+breakdown field, allowing high operating voltages. Currently explored WBG
+materials for power electronics are costly (GaN), difficult to synthesize as
+high-quality single crystals (SiC) and at scale (diamond, BN), have low thermal
+conductivity ($\beta$-Ga$_2$O$_3$), or cannot be suitably doped (AlN). We
+conduct a computational search for novel semiconductors across 1,340 known
+metal-oxides using first-principles calculations and existing transport models.
+We calculate the Baliga figure of merit (BFOM) and lattice thermal conductivity
+($\kappa_L$) to identify top candidates for n-type power electronics. We find
+40 mostly ternary oxides that have higher $\kappa_L$ than $\beta$-Ga$_2$O$_3$
+and higher n-type BFOM than SiC and GaN. Among these, several material classes
+emerge, including 2-2-7 stoichiometry thortveitites and pyrochlores, II-IV
+spinels, and calcite-type borates. Within these classes, we propose
+In$_2$Ge$_2$O$_7$, Mg$_2$GeO$_4$, and InBO$_3$ as they are the most favorable
+for n-type doping based on our preliminary evaluation and could be grown as
+single crystals or thin film heterostructures. These materials could help
+advance power electronic devices for the future grid.",2204.09158v1
+2022-05-04,Direct observation of nodeless superconductivity and phonon modes in electron-doped copper oxide Sr$_{1-x}$Nd$_x$CuO$_2$,"The microscopic understanding of high-temperature superconductivity in
+cuprates has been hindered by the apparent complexity of crystal structures in
+these materials. We used scanning tunneling microscopy and spectroscopy to
+study an electron-doped copper oxide compound Sr$_{1-x}$Nd$_x$CuO$_2$ that has
+only bare cations separating the CuO$_2$ planes and thus the simplest
+infinite-layer structure among all cuprate superconductors. Tunneling
+conductance spectra of the major CuO$_2$ planes in the superconducting state
+revealed direct evidence for a nodeless pairing gap, regardless of variation of
+its magnitude with the local doping of trivalent neodymium. Furthermore, three
+distinct bosonic modes are observed as multiple peak-dip-hump features outside
+the superconducting gaps and their respective energies depend little on the
+spatially varying gaps. Along with the bosonic modes with energies identical to
+those of the external, bending and stretching phonons of copper oxides, our
+findings indicate their origin from lattice vibrations rather than spin
+excitations.",2205.01843v1
+2022-05-06,The role of atomization in the coupling between doped droplets dynamics and their flames,"The droplet and flame chemiluminescence dynamics as well as their coupling
+during atomization events of graphene oxide doped diesel are investigated
+experimentally. The tested doping concentrations are 0, 0.001, 0.005, 0.01, and
+0.02% by weight. To minimize heat transfer between the droplet and its
+suspension mechanism, small diameter fibers are used for the droplet
+suspension. Separate shadowgraphy and OH* chemiluminescence measurements are
+performed at 4000 Hz to study the droplet and flame dynamics, respectively. The
+results show that both the droplet diameter squared and the flame
+chemiluminescence feature intermittent oscillations. The droplet diameter
+squared oscillations RMS is positively related to the number and intensity of
+the atomization events and the graphene oxide doping concentration. The
+probability density function of the inverse of the time separation between two
+consecutive atomization events and the power spectrum density of the droplet
+diameter squared oscillations feature dominant large probabilities and powers
+at about 25 Hz prior to the occurrence of the first intense atomization event.
+After the occurrence of the first intense atomization event, this frequency
+decreases to about 5 Hz for both. Although the intense atomization triggers the
+large amplitude oscillations at 5 Hz, it was argued that the retracting motion
+of the igniter induces the oscillations at 25 Hz. Our findings suggest that the
+atomization events are the root cause of the smaller frequency coupling between
+liquid fuel droplets doped with graphene oxide and their flames. This has
+implications for spray combustion research.",2205.02966v1
+2022-06-04,Metal Oxide-Vertical Graphene Nanosheets for 2.6 V Aqueous Electrochemical Hybrid Capacitor,"Aqueous asymmetric electrochemical capacitor, with their high power density
+and superior cycle stability in comparison to conventional batteries, are
+presently considered as the most promising contender for energy storage.
+However, fabricating an electrode material and choosing a suitable aqueous
+electrolyte are vital in developing an electrochemical capacitor device with
+high charge storage capacity. Herein, we report a feasible method to synthesize
+MnO2/Vertical graphene nanosheets (VGN) and Fe2O3/VGN as positive and negative
+electrodes, respectively. The surface of VGN skeleton is independently
+decorated with MnO2 having sponge gourd-like morphology and Fe2O3 having
+nanorice like morphology. A schematic representation of the growth mechanism
+for metal oxide on VGN network is established. Both the electrode have shown
+around 250 times higher charge-storage capacity than the bare VGN (0.47 mF/cm2)
+with the specific capacitance of 118 (MnO2/VGN) and 151 mF/cm2 (Fe2O3/VGN). In
+addition to the double layer capacitance contribution, the porous
+interconnected vertical graphene architecture serves as a mechanical backbone
+for the metal oxide materials and provides multiple conducting channels for the
+electron transport. The fabricated asymmetric device exhibited a specific
+capacitance of 76 mF/cm2 and energy density of 71 microWh/cm2 with an excellent
+electrochemical stability up to 12000 cycles, over a potential window of 2.6 V.
+The commendable performance of asymmetric electrochemical capacitor device
+authenticated its potential utilization for next-generation portable energy
+storage device.",2206.01998v1
+2022-06-16,Scalable Composites Benefiting from Transition-Metal Oxides as Cathode Materials for Efficient Lithium-Sulfur Batteries,"Composite materials achieved by including transition-metal oxides with
+different structures and morphologies in sulfur are suggested as scalable
+cathodes for high-energy lithium-sulfur (Li-S) batteries. The composites
+contain 80 wt.% sulfur and 20 wt.% of either MnO2 or TiO2, leading to a sulfur
+content in the electrode of 64 wt.% and revealing a reversible, fast, and lowly
+polarized conversion process in the cell with limited interphase resistance.
+The S-TiO2 composite exhibits an excellent rate capability between C/10 and 2C,
+and a cycle life extended over 400 cycles at 2C, owing to the effects of the
+nanometric TiO2 additive in boosting the reaction kinetics. Instead, the
+micrometric sized particles of MnO2 partially limit the electrochemical
+activity of S-MnO2 to the current rate of 1C. Nevertheless, both S-MnO2 and
+S-TiO2 withstand a sulfur loading up to values approaching 6 mgcm-2, and
+deliver an areal capacit ranging from about 4.5 to 5.5 mAhcm-2 at C/5. The
+excellent performances of the metal oxide-sulfur electrodes, even at high
+active material loading, and the possible scalability of the synthetic pathway
+adopted in the work suggest that the composites are viable cathodes for
+next-generation Li-S batteries with high energy density and efficient
+electrochemical process.",2206.14569v1
+2022-06-29,Optical properties of oxygen-containing yttrium hydride thin films during and after the deposition,"The synthesis of the photochromic YHO films is based on the oxidation of
+deposited yttrium hydride in ambient conditions. The actual state of the films
+during the deposition process, which is influenced by the deposition pressure
+and the oxidation caused by the residual gases, is not completely known. We
+report on the YHxOy thin films deposited by reactive pulsed-DC magnetron
+sputtering. Since the visible light transmittance is closely related to the
+phase and chemical composition of the films, in-situ transmittance measurements
+during and after deposition are performed. Ex-situ spectroscopic ellipsometry
+is used to determine the optical constants of YHxOy throughout the film
+thickness. In order to obtain metallic YH2-x films, the densest possible
+structure with a high deposition rate is required, otherwise the films could
+already be partially transparent during the deposition. The transmittance is
+higher if deposition pressure is increased. This is because of the oxidation
+promoted by more porous growth of the microstructure that is observed at the
+surface and cross-section images of the films. The films exhibit a refractive
+index gradient perpendicular to the substrate surface, which is related to the
+porosity and variation of the chemical composition.",2206.14644v1
+2022-06-29,Tailoring of rhenium oxidation state in ReOx thin films during reactive HiPIMS deposition process and following annealing,"Bulk rhenium trioxide (ReO3) has an unusually high electrical conductivity
+and, being nanosized, has promising catalytic properties. However, the
+production of pure ReO3 thin films is challenging due to the difficulty to
+stabilize rhenium in a 6+ oxidation state. Here we present a novel approach for
+the deposition of ReOx (x = 1.6-2.9) thin films using reactive high power
+impulse magnetron sputtering (r-HiPIMS) from a metallic rhenium target in a
+mixed Ar/O2 atmosphere. The thin films were deposited in the gas-sustained
+self-sputtering regime, observed during r-HiPIMS process according to current
+waveforms. The influence of the substrate temperature, the oxygen-to-argon flow
+ratio and post-annealing at 250 {\deg}C in the air for 3 h on the properties of
+the films were studied. The as-deposited films have an X-ray amorphous
+structure (a-ReOx) when deposited at room temperature while a nano-crystalline
+\b{eta}-ReO2 phase when deposited at elevated temperatures (150 or 250
+{\deg}C). The amorphous a-ReOx can be converted into the crystalline ReO3 with
+a lattice parameter of 3.75 {\AA} upon annealing in the air. The surface
+morphology of the films is dense without detectable voids when elevated
+substrate temperatures are used. Various Re oxidation states are observed on
+the surface of the films in different ratios depending on the deposition
+parameters. All samples exhibit electrical resistivity on the order of 10-3
+Ohmxcm and optical properties typical for thin metallic films.",2206.14665v1
+2022-07-12,Amorphous p-Type Conducting Zn-x Ir Oxide (x > 0.13) Thin Films Deposited by Reactive Magnetron Cosputtering,"Zinc-iridium oxide (Zn-Ir-O) thin films have been demonstrated as a p-type
+conducting material. However, the stability of p-type conductivity with respect
+to chemical composition or temperature is still unclear. In this study we
+discuss the local atomic structure and the electrical properties of Zn-Ir-O
+films in the large Ir concentration range. The films are deposited by reactive
+DC magnetron co-sputtering at two different substrate temperatures-without
+intentional heating and at 300 {\deg}C. Extended X-ray absorption fine
+structure (EXAFS) analysis reveals that strongly disordered ZnO4 tetrahedra are
+the main Zn complexes in Zn-Ir-O films with up to 67.4 at% Ir. As the Ir
+concentration increases, an effective increase of Ir oxidation state is
+observed. Reverse Monte Carlo analysis of EXAFS at Zn K-edge shows that the
+average Zn-O interatomic distance and disorder factor increase with the Ir
+concentration. We observed that the nano-crystalline w-ZnO structure is
+preserved in a wider Ir concentration range if the substrate is heated during
+deposition. At low Ir concentration, the transition from n- to p-type
+conductivity is observed regardless of the temperature of the substrates.
+Electrical resistivity decreases exponentially with the Ir concentration in the
+Zn-Ir-O films.",2207.05438v1
+2022-07-18,Direct visualization of Rashba-split bands and spin/orbital-charge interconversion at KTaO$_3$ interfaces,"Rashba interfaces have emerged as promising platforms for spin-charge
+interconversion through the direct and inverse Edelstein effects. Notably,
+oxide-based two-dimensional electron gases (2DEGs) display a large and
+gate-tunable conversion efficiency, as determined by transport measurements.
+However, a direct visualization of the Rashba-split bands in oxide 2DEGs is
+lacking, which hampers an advanced understanding of their rich spin-orbit
+physics. Here, we investigate KTaO$_3$-2DEGs and evidence their Rashba-split
+bands using angle resolved photoemission spectroscopy. Fitting the bands with a
+tight-binding Hamiltonian, we extract the effective Rashba coefficient and
+bring insight into the complex multiorbital nature of the band structure. Our
+calculations reveal unconventional spin and orbital textures, showing
+compensation effects from quasi-degenerate band pairs which strongly depend on
+in-plane anisotropy. We compute the band-resolved spin and orbital Edelstein
+effects, and predict interconversion efficiencies exceeding those of other
+oxide 2DEGs. Finally, we suggest design rules for Rashba systems to optimize
+spin-charge interconversion performance.",2207.08698v1
+2022-07-20,Adatom and nanoparticle dynamics on single-atom catalyst substrates,"Single-atom catalysts represent an essential and ever-growing family of
+heterogeneous catalysts. Recent studies indicate that besides the valuable
+catalytic properties provided by single-atom active sites, the presence of
+single-atom sites on the catalyst substrates may significantly influence the
+population of supported metal nanoparticles coexisting with metal single atoms.
+Treatment of ceria-based single-atom catalysts in oxidizing or reducing
+atmospheres was proven to provide precise experimental control of the size of
+the supported Pt nanoparticles, and, correspondingly, control of catalyst
+activity and stability. Based on dedicated surface science experiments,
+ab-initio calculations and kinetic Monte-Carlo simulations we demonstrate that
+the morphology of Pt nanoparticle population on ceria surface is a result of a
+competition for Pt atoms between Pt single-atom sites and Pt nanoparticles. In
+oxidizing atmosphere, Pt single-atom sites provide strong bonding to single Pt
+atoms and Pt nanoparticles shrink. In reducing atmosphere, Pt single atom sites
+are depopulated and Pt nanoparticles grow. We formulate a generic model of Pt
+redispersion and coarsening on ceria substrates. Our model provides a unified
+atomic-level explanation for a variety of metal nanoparticle dynamic processes
+observed in single-atom catalysts under stationary or alternating
+oxidizing/reducing atmospheres, and allows to classify the conditions when
+nanoparticle ensembles on single-atom catalysts substrates can be stabilized
+against Ostwald ripening.",2207.09749v1
+2022-08-23,Theoretical Study of Electronic Transport in Two-Dimensional Transition Metal Dichalcogenides: Effects of the Dielectric Environment,"We discuss the effect of the dielectric environment (insulators and metal
+gates) on electronic transport in two-dimensional (2D) transition metal
+dichalcogenides (TMD) monolayers. We employ well-known ab initio methods to
+calculate the low-field carrier mobility in free-standing layers and use the
+dielectric continuum approximation to extend our study to layers in double-gate
+structures, including the effects of dielectric screening of the
+electron-phonon interaction caused by the bottom oxide and the gate insulator,
+and of scattering with hybrid interface optical-phonon/plasmon excitations
+(`remote phonon scattering'). We find that the presence of insulators with a
+high dielectric constant may improve significantly the carrier mobility.
+However, scattering with the interface hybrid excitations negates this gain and
+degrades the mobility significantly below its free-standing value. In a
+double-gate geometry with SiO$_{2}$ as bottom-oxide and various top-gate
+insulators, we find that the mobility decreases as the top-insulator dielectric
+constant increases, as expected. However, a high mobility is predicted in the
+case of the weakly polar hBN, and a mobility much lower than expected is
+calculated in the case of gate-insulator/TMD/bottom-oxide stacks in which two
+or more polar materials have optical-phonon with similar resonating
+frequencies. We also find that the effect of screening by metal gates is
+noticeable but not particularly strong. Finally, we discuss the effect of the
+TMD dielectric constant, of the free-carrier density, and of temperature on the
+transport properties of TMD monolayers.",2208.11031v1
+2022-09-28,Functional thin films as cathode/electrolyte interlayers: a strategy to enhance the performance and durability of solid oxide fuel cells,"Electrochemical devices such as solid oxide fuel cells (SOFC) may greatly
+benefit from the implementation of nanoengineered thin-film multifunctional
+layers providing, alongside enhanced electrochemical activity, improved
+mechanical, and long-term stability. In this study, an ultrathin (400 nm)
+bilayer of samarium-doped ceria and a self-assembled nanocomposite made of
+Sm0.2Ce0.8O1.9-La0.8Sr0.2MnO3-$\delta$ was fabricated by pulsed laser
+deposition and is employed as a functional oxygen electrode in an
+anode-supported solid oxide fuel cell. Introducing the functional bilayer in
+the cell architecture results in a simple processing technique for the
+fabrication of high-performance fuel cells (power density 1.0 W.cm-2 at 0.7 V
+and 750 $^\circ$C). Durability tests were carried out for up to 1500 h, showing
+a small degradation under extreme operating conditions of 1 A.cm-2, while a
+stable behaviour at 0.5 A.cm-2. Post-test analyses, including scanning and
+transmission electron microscopy and electrochemical impedance spectroscopy,
+demonstrate that the nanoengineered thin film layers remain mostly
+morphologically stable after the operation.",2209.14374v1
+2022-10-26,Two-Dimensional Charge Localization at the Perovskite Oxide Interface,"The effects of atomic-scale disorder and charge (de)localization holds
+significant importance,and they provide essential insights in unravelling the
+role that strong and weak correlations play in condensed matter systems.For
+perovskite oxide heterostructures,while disorders introduced via various
+external stimuli have strong influences on the (de)localization of the
+interfacial two-dimensional (2D) electrons, these factors alone could not fully
+account for the system's charge dynamics where interfacial hybridization holds
+very strong influence.Here, we determine that the displaced 2D free electrons
+are localized in the specific hybridized states at the LaAlO3/SrTiO3(LAO/STO)
+interface.This experimental study combines both transport measurements and
+temperature-dependent X-ray absorption spectroscopy and suggests the
+localization of 2D electrons can be induced via temperature reduction or ionic
+liquid gating and it applies to both amorphous and crystalline interfacial
+systems.Specifically, we demonstrate that interfacial hybridization plays a
+pivotal role in regulating the 2D electron localization effects.Our study
+resolves the location where the 2D electrons are localized and highlights the
+importance of interfacial hybridization and opens further scientific
+investigation of its influence on 2D charge localization in oxide
+heterointerfaces.",2210.14435v1
+2022-10-26,Visualizing giant ferroelectric gating effects in large-scale WSe$_2$/BiFeO$_3$ heterostructures,"Multilayers based on quantum materials (complex oxides, topological
+insulators, transition-metal dichalcogenides, etc) have enabled the design of
+devices that could revolutionize microelectronics and optoelectronics. However,
+heterostructures incorporating quantum materials from different families remain
+scarce, while they would immensely broaden the range of possible applications.
+Here we demonstrate the large-scale integration of compounds from two
+highly-multifunctional families: perovskite oxides and transition-metal
+dichalcogenides (TMDs). We couple BiFeO$_3$, a room-temperature multiferroic
+oxide, and WSe$_2$, a semiconducting two-dimensional material with potential
+for photovoltaics and photonics. WSe$_2$ is grown by molecular beam epitaxy and
+transferred on a centimeter-scale onto BiFeO$_3$ films. Using angle-resolved
+photoemission spectroscopy, we visualize the electronic structure of 1 to 3
+monolayers of WSe$_2$ and evidence a giant energy shift as large as 0.75 eV
+induced by the ferroelectric polarization direction in the underlying
+BiFeO$_3$. Such a strong shift opens new perspectives in the efficient
+manipulation of TMDs properties by proximity effects.",2210.14786v1
+2022-11-02,Tunable Rapid Electron Transport in Titanium Oxide Thin Films,"Rapid electron transport in the quantum well triggers many novel physical
+phenomena and becomes a critical point for the high-speed electronics. Here, we
+found electrical properties of the titanium oxide changed from semiconducting
+to metallic as the degree of oxidation decreased and Schottky quantum well was
+formed at the interface. We take the asymmetry interface electron scattering
+effect into consideration when studying the electrical transport properties of
+the multilayer thin films. A novel physical conductivity model for the
+multilayer thin films was developed. We found electron would be transferred
+from the low-mobility semiconducting and metallic conductive channels to the
+high-mobility Schottky quantum well conductive channel with an in-plane applied
+electric field. Electron concentration and mobility of the forming 2DEG in the
+Schottky quantum well could be tuned thus the nano-devices exhibited non-linear
+voltage-current curves. The differential resistivity of the nano-devices could
+decrease by two orders with increasing electric field at room temperature. Weak
+electron localization of electrons has been experimentally observed in our
+nano-devices at low temperature, which further demonstrated the existence of
+2DEG in the Schottky quantum well. Our work will provide us new physics about
+the rapid electron transport in the multilayer thin films, and bring novel
+functional devices for the modern microelectronic industry.",2211.01162v1
+2022-11-07,Room temperature charge-to-spin conversion from q-2DEG at SrTiO3-based interfaces,"Interfacial two-dimensional electron gas (2DEG), especially the SrTiO3-based
+ones at the unexpected interface of insulators, have emerged to be a promising
+candidate for efficient charge-spin current interconversion. In this article,
+to gain insight into the mechanism of the charge-spin current interconversion
+at the oxide-based 2DEG, we focused on conducting interfaces between insulating
+SrTiO3 and two types of aluminium-based amorphous insulators, namely SrTiO3/AlN
+and SrTiO3/Al2O3, and estimated their charge-spin conversion efficiency,
+{\theta}_cs. The two types of amorphous insulators were selected to explicitly
+probe the overlooked contribution of oxygen vacancy to the {\theta}_cs. We
+proposed a mechanism to explain results of spin-torque ferromagnetic resonance
+(ST-FMR) measurements and developed an analysis protocol to reliably estimate
+the {\theta}_cs of the oxide based 2DEG. The resultant {\theta}_cs/t, where t
+is the thickness of the 2DEG, were estimated to be 0.244 nm-1 and 0.101 nm-1
+for the SrTiO3/AlN and SrTiO3/Al2O3, respectively, and they are strikingly
+comparable to their crystalline counterparts. Furthermore, we also observe a
+large direct current modulation of resonance linewidth in SrTiO3/AlN samples,
+confirming its high {\theta}_cs and attesting an oxygen-vacancy-enabled
+charge-spin conversion. Our findings emphasize the defects' contribution to the
+charge-spin interconversion, especially in the oxide-based low dimensional
+systems, and provide a way to create and enhance charge-spin interconversion
+via defect engineering.",2211.03383v1
+2022-12-01,Investigation of process history and phenomenology of plutonium oxides using vector quantizing variational autoencoder,"Accurate, high throughput, and unbiased analysis of plutonium oxide particles
+is needed for analysis of the phenomenology associated with process parameters
+in their synthesis. Compared to qualitative and taxonomic descriptors,
+quantitative descriptors of particle morphology through scanning electron
+microscopy (SEM) have shown success in analyzing process parameters of uranium
+oxides. We utilize a VQ-VAE to quantitatively describe plutonium dioxide (PuO2)
+particles created in a designed experiment and investigate their phenomenology
+and prediction of their process parameters. PuO2 was calcined from Pu(III)
+oxalates that were precipitated under varying synthetic conditions that related
+to concentrations, temperature, addition and digestion times, precipitant feed,
+and strike order; the surface morphology of the resulting PuO2 powders were
+analyzed by SEM. A pipeline was developed to extract and quantify useful image
+representations for individual particles with the VQ-VAE to perform multiple
+classification tasks simultaneously. The reduced feature space could predict
+process parameters with greater than 80% accuracies for some parameters with a
+single particle. They also showed utility for grouping particles with similar
+surface morphology characteristics together. Both the clustering and
+classification results reveal valuable information regarding which chemical
+process parameters chiefly influence the PuO2 particle morphologies: strike
+order and oxalic acid feedstock. Doing the same analysis with multiple
+particles was shown to improve the classification accuracy on each process
+parameter over the use of a single particle, with statistically significant
+results generally seen with as few as four particles in a sample.",2212.00887v2
+2022-12-02,Dynamics of the Great Oxidation Event from a 3D photochemical-climate model,"From the Archean toward the Proterozoic, the Earth's atmosphere underwent a
+major shift from anoxic to oxic conditions, around 2.4 to 2.1 Gyr, known as the
+Great Oxidation Event (GOE). This rapid transition may be related to an
+atmospheric instability caused by the formation of the ozone layer. Previous
+works were all based on 1D photochemical models. Here, we revisit the GOE with
+a 3D photochemical-climate model to investigate the possible impact of the
+atmospheric circulation and the coupling between the climate and the dynamics
+of the oxidation. We show that the diurnal, seasonal and transport variations
+do not bring significant changes compared to 1D models. Nevertheless, we
+highlight a temperature dependence for atmospheric photochemical losses. A
+cooling during the late Archean could then have favored the triggering of the
+oxygenation. In addition, we show that the Huronian glaciations, which took
+place during the GOE, could have introduced a fluctuation in the evolution of
+the oxygen level. Finally, we show that the oxygen overshoot which is expected
+to have occurred just after the GOE, was likely accompanied by a methane
+overshoot. Such high methane concentrations could have had climatic
+consequences and could have played a role in the dynamics of the Huronian
+glaciations.",2212.01389v1
+2022-12-11,Strain induced variations in transport and optical properties of SrVO$_3$: a DFT+U study,"First-principles calculations based on density functional theory + Hubbard U
+(DFT+U) approach have been carried out to study the strain induced variations
+in the optical and transport properties of the correlated perovskite SrVO$_3$.
+By virtue of its conductivity, high carrier mobility and optical transparency,
+SrVO$_3$ can be used as a potential replacement of indium tin oxide (ITO) as a
+transparent conductor. As strain tuning is an effective way to tune the
+electron-electron correlations in correlated oxides, the epitaxial strain
+induced variations in V-3d bandwidth, band center shift and band splitting at
+high symmetry points (${\Gamma}$, R) in SrVO$_3$ are investigated. The
+alterations in resistivity, carrier concentration, Hall coefficient and plasma
+frequency with applied strain are also elucidated. Our calculations revealed
+that under tensile strain, the lifting of the threefold degeneracy of
+3d-t$_{2g}$ orbital and d-band narrowing reinforces a relatively less
+conducting state thus limiting the $\omega_P$ to lower frequencies. On the
+contrary, in case of compressive strain the d-band widening predominates
+leading to an increase in carrier concentration and decrease in resistivity
+enhancing the metallic state. As a result, $\omega_P$ is increased to higher
+frequencies which decreases the optical transparency window. Hence, our results
+and findings clearly demonstrate the interdependence between the optical and
+transport properties, and provides a detailed mechanism to tune the
+optoelectronic properties of SrVO$_3$ for its applications as a transparent
+conducting oxide.",2212.05449v1
+2022-12-13,Improving Josephson junction reproducibility for superconducting quantum circuits: shadow evaporation and oxidation,"The most commonly used physical realization of superconducting qubits for
+quantum circuits is a transmon. There are a number of superconducting quantum
+circuits applications, where Josephson junction critical current
+reproducibility over a chip is crucial. Here, we report on a robust chip scale
+$Al/AlO_x/Al$ junctions fabrication method due to comprehensive study of shadow
+evaporation and oxidation steps. We experimentally demonstrate the evidence of
+optimal Josephson junction electrodes thickness, deposition rate and deposition
+angle, which ensure minimal electrode surface and line edge roughness. The
+influence of oxidation method, pressure and time on critical current
+reproducibility is determined. With the proposed method we demonstrate
+$Al/AlO_x/Al$ junction fabrication with the critical current variation
+($\sigma/I_c$) less than 3.9% (from $150\times200$ to $150\times600$ $nm^2$
+area) and 7.7% (for $100\times100$ $nm^2$ area) over $20\times20$ $mm^2$ chip.
+Finally, we fabricate separately three $5\times10$ $mm^2$ chips with 18
+transmon qubits (near 4.3 GHz frequency) showing less than 1.9% frequency
+variation between qubit on different chips. The proposed approach and
+optimization criteria can be utilized for a robust wafer-scale superconducting
+qubit circuits fabrication.",2212.06692v1
+2022-12-20,Wafer-Scale Fabrication of Hierarchically Porous Silicon and Silica Glass by Active Nanoparticle-Assisted Chemical Etching and Pseudomorphic Thermal Oxidation,"Many biological materials exhibit a multiscale porosity with small, mostly
+nanoscale pores as well as large, macroscopic capillaries to simultaneously
+achieve optimized mass transport capabilities and lightweight structures with
+large inner surfaces. Realizing such a hierarchical porosity in artificial
+materials necessitates often sophisticated and expensive top-down processing
+that limits scalability. Here we present an approach that combines
+self-organized porosity based on metal-assisted chemical etching (MACE) with
+photolithographically induced macroporosity for the synthesis of
+single-crystalline silicon with a bimodal pore-size distribution, i.e.,
+hexagonally arranged cylindrical macropores with 1 micrometer diameter
+separated by walls that are traversed by mesopores 60 nm across. The MACE
+process is mainly guided by a metal-catalyzed reduction-oxidation reaction,
+where silver nanoparticles (AgNPs) serve as the catalyst. In this process, the
+AgNPs act as self-propelled particles that are constantly removing silicon
+along their trajectories. High-resolution X-ray imaging and electron tomography
+reveal a resulting large open porosity and inner surface for potential
+applications in high-performance energy storage, harvesting and conversion or
+for on-chip sensorics and actuorics. Finally, the hierarchically porous silicon
+membranes can be transformed structure-conserving by thermal oxidation into
+hierarchically porous amorphous silica, a material that could be of particular
+interest for opto-fluidic and (bio-)photonic applications due to its multiscale
+artificial vascularization.",2212.10160v1
+2022-12-21,Defeating depolarizing fields with artificial flux closure in ultrathin ferroelectrics,"Material surfaces encompass structural and chemical discontinuities that
+often lead to the loss of the property of interest in the so-called dead
+layers. It is notably problematic in nanoscale oxide electronics, where the
+integration of strongly correlated materials into devices is obstructed by the
+thickness threshold required for the emergence of their functionality. Here, we
+report the stabilization of ultrathin out-of-plane ferroelectricity in oxide
+heterostructures through the design of an artificial flux-closure architecture.
+Inserting an in-plane polarized ferroelectric epitaxial buffer provides
+continuity of polarization at the interface, and despite its insulating nature
+we observe the emergence of polarization in our out-of-plane-polarized model
+ferroelectric BaTiO$_{3}$ from the very first unit cell. In BiFeO$_{3}$, the
+flux-closure approach stabilizes a conceptually novel 251$^{\circ}$ domain
+wall. Its unusual chirality is likely associated with the ferroelectric analog
+to the Dzyaloshinskii-Moriya interaction. We thus see that in an adaptively
+engineered geometry, the depolarizing-field-screening properties of an
+insulator can even surpass those of a metal and be a source of new
+functionalities. This should be a useful insight on the road towards the next
+generation of ferroelectric-based oxide electronics.",2212.11073v1
+2022-12-27,Compositionally Complex Perovskite Oxides as a New Class of Li-Ion Solid Electrolytes,"Compositionally complex ceramics (CCCs), including high-entropy ceramics
+(HECs) as a subclass, offer new opportunities of materials discovery beyond the
+traditional methodology of searching new stoichiometric compounds. Herein, we
+establish new strategies of tailoring CCCs via a seamless combination of (1)
+non-equimolar compositional designs and (2) controlling microstructures and
+interfaces. Using oxide solid electrolytes for all-solid-state batteries as an
+exemplar, we validate these new strategies via discovering a new class of
+compositionally complex perovskite oxides (CCPOs) to show the possibility of
+improving ionic conductivities beyond the limit of conventional doping. As an
+example (amongst the 28 CCPOs examined), we demonstrate that the ionic
+conductivity can be improved by >60% in
+(Li0.375Sr0.4375)(Ta0.375Nb0.375Zr0.125Hf0.125)O3-{\delta}, in comparison with
+the state-of-art (Li0.375Sr0.4375)(Ta0.75Zr0.25)O3-{\delta} (LSTZ) baseline,
+via maintaining comparable electrochemical stability. Furthermore, the ionic
+conductivity can be improved by another >70% via grain boundary (GB)
+engineering, achieving >270% of the LSTZ baseline. This work suggests
+transformative new strategies for designing and tailoring HECs and CCCs,
+thereby opening a new window for discovering materials for energy storage and
+many other applications.",2212.13451v1
+2023-01-03,"Extracting optical parameters of Cu-Mn-Fe spinel oxide nanoparticles for optimizing air-stable, high-efficiency solar selective coatings","High-temperature Cu-Mn-Fe spinel-oxide nanoparticle solar selective absorber
+coatings are investigated experimentally and theoretically. A reliable, general
+approach to evaluate absorption coefficient spectra from the optical
+measurements of the nanoparticle-pigmented coatings is developed based on
+solving the inverse problem using four-flux-radiative method. The derived
+absorption properties of NP materials can be directly applied to predict the
+solar absorptance, optimize the nanoparticle-pigmented coatings, and analyze
+the thermal degradation, which agree well with the experimental results. The
+analysis reveals that the Cu-Mn-Fe spinel oxides are fundamentally indirect
+bandgap ranging from 1.7 to 2.1 eV, while iron-free CuMn2O4 is a direct bandgap
+material with Eg=1.84 eV. With the same coating thickness and nanoparticle
+load, the solar absorptance ranks in the order of Mn2O3 < MnFe2O4 < CuFe2O4 <
+CuFeMnO4 < CuMn2O4. The optimized spray-coated iron-free CuMn2O4 NP-pigmented
+coating demonstrates a high solar absorptance of 97%, a low emittance of 55%, a
+high optical-to-thermal energy conversion efficiency of ~93.5 % under 1000x
+solar concentration at 750 degrees C, and long-term endurance upon thermal
+cycling between 750{\deg}C and room temperature in air. The optical parameter
+analysis approach can be easily extended to other material systems to
+facilitate the searching and optimizing high-temperature pigmented-solar
+selective coatings.",2301.01194v1
+2023-01-03,Spinel Cu-Mn-Cr Oxide Nanoparticle-Pigmented Solar Selective Coatings Maintaining >94% Efficiency at 750 degrees C,"High-temperature concentrating solar power (CSP) system is capable of
+harvesting and storing solar energy as heat towards cost-effective dispatchable
+solar electricity. Solar selective coating is a critical component to boost its
+efficiency by maximizing solar absorptance and minimizing thermal emittance
+losses. However, maintaining a high solar-thermal conversion efficiency >90%
+for long-term operation at >750 degrees C remains a significant challenge.
+Herein, we report spray-coated spinel Cu-Mn-Cr oxide nanoparticle-pigmented
+solar selective coatings on Inconel tube sections maintaining >94% efficiency
+at 750 degrees C and >92.5% at 800 degrees C under 1000x solar concentration
+after 60 simulated day-night thermal cycles in air, each cycle comprising 12h
+at 750 degrees C/800 degrees C and 12h cooling to 25 degrees C. The solar
+spectral selectivity is intrinsic to the band-to-band and d-d transitions of
+non-stoichiometric spinel Cu-Mn-Cr oxide nanoparticles by balancing the lattice
+site inversion of Cu2+ and Mn3+ on tetrahedral vs. octahedral sites. This
+feature offers a large fabrication tolerance in nanoparticle volume fraction
+and coating thickness, facilitating low-cost and scalable spray-coated
+high-efficiency solar selective absorbers for high-temperature CSP systems.",2301.01265v1
+2023-01-19,Illuminating trap density trends in amorphous oxide semiconductors with ultrabroadband photoconduction,"Under varying growth and device processing conditions, ultrabroadband
+photoconduction (UBPC) reveals strongly evolving trends in the defect density
+of states (DoS) for amorphous oxide semiconductor thin-film transistors (TFTs).
+Spanning the wide bandgap of amorphous InGaZnO$_x$ (a-IGZO), UBPC identifies
+seven oxygen-deep donor vacancy peaks that are independently confirmed by
+energetically matching to photoluminescence emission peaks. The sub-gap DoS
+from 15 different types of a-IGZO TFTs all yield similar DoS, except only
+back-channel etch TFTs can have a deep acceptor peak seen at 2.2 eV below the
+conduction band mobility edge. This deep acceptor is likely a zinc vacancy,
+evidenced by trap density which becomes 5-6x larger when TFT wet-etch methods
+are employed. Certain DoS peaks are strongly enhanced for TFTs with active
+channel processing damage caused by plasma exposure. While Ar implantation and
+He plasma processing damage are similar, Ar plasma yields more disorder showing
+a 2x larger valence-band Urbach energy and two orders of magnitude increase in
+the deep oxygen vacancy trap density. Changing the growth conditions of a-IGZO
+also impacts the DoS, with zinc-rich TFTs showing much poorer electrical
+performance compared to 1:1:1 molar ratio a-IGZO TFTs owing to the former
+having a ~10xlarger oxygen vacancy trap density. Finally, hydrogen is found to
+behave as a donor in amorphous indium tin gallium zinc oxide TFTs.",2301.08196v1
+2023-03-13,Probing Interface of Perovskite Oxide Using Surface-specific Terahertz Spectroscopy,"The surface/interface species in perovskite oxides play an essential role in
+many novel emergent physical phenomena and chemical processes. With low
+eigen-energy in the terahertz region, such species at buried interfaces remain
+poorly understood due to the lack of feasible experimental techniques. Here, we
+show that vibrational resonances and two-dimensional electron gas at the
+interface can be characterized using surface-specific nonlinear spectroscopy in
+the terahertz range. This technique uses intra-pulse difference frequency
+mixing (DFM) process, which is allowed only at surface/interface of a medium
+with inversion symmetry. Sub-monolayer sensitivity can be achieved using the
+state-of-the-art detection scheme for the terahertz emission from
+surface/interface. As a demonstration, Drude-like nonlinear response from the
+two-dimensional electron gas emerging at LaAlO3/SrTiO3 or Al2O3/ SrTiO3
+interface was successfully observed. Meanwhile, the interfacial vibrational
+spectrum of the ferroelectric soft mode of SrTiO3 at 2.8 THz was also obtained
+that was polarized by the surface field in the interfacial region. The
+corresponding surface/interface potential, which is a key parameter for
+SrTiO3-based interface superconductivity and photocatalysis, can now be
+determined optically via quantitative analysis on the polarized phonon
+spectrum. The interfacial species with resonant frequencies in the THz region
+revealed by our method provide more insights into the understanding of physical
+properties of complex oxides.",2303.07871v1
+2023-03-16,Chemical bonding in americium oxides: x-ray spectroscopic view,"The electronic structure and the chemical state in Am binary oxides and
+Am-doped UO$_2$ were studied by means of x-ray absorption spectroscopy at
+shallow Am core ($4d$ and $5d$) edges. In particular, the Am $5f$ states were
+probed and the nature of their bonding to the oxygen states was analyzed. The
+interpretation of the experimental data was supported by the Anderson impurity
+model (AIM) calculations which took into account the full multiplet structure
+due to the interaction between $5f$ electrons as well as the interaction with
+the core hole. The sensitivity of the branching ratio of the Am $4d_{3/2}$ and
+$4d_{5/2}$ x-ray absorption lines to the chemical state of Am was shown using
+Am binary oxides as reference systems. The observed ratio for Am-doped UO$_2$
+suggests that at least at low Am concentrations, americium is in the Am(III)
+state in the UO$_2$ lattice. To confirm the validity of the applied AIM
+approach, the analysis of the Am $4f$ x-ray photoelectron spectra of AmO$_2$
+and Am$_2$O$_3$ was also performed which revealed a good agreement between
+experiment and calculations. As a whole, AmO$_2$ can be classified as the
+charge-transfer compound with the $5f$ occupancy ($n_f$) equal to 5.73
+electrons, while Am$_2$O$_3$ is rather a Mott-Hubbard system with $n_f$=6.05.",2303.09247v1
+2023-04-04,Ultrathin Stable Ohmic Contacts for High-Temperature Operation of $β$-Ga$_2$O$_3$ Devices,"Beta gallium oxide ($\beta$-Ga$_2$O$_3$) shows significant promise in the
+high-temperature, high-power, and sensing electronics applications. However,
+long-term stable metallization layers for Ohmic contacts at high temperature
+present unique thermodynamic challenges. The current most common Ohmic contact
+design based on 20 nm of Ti has been repeatedly demonstrated to fail at even
+moderately elevated temperatures (300-400$^{\circ}$C) due to a combination of
+non-stoichiometric Ti/Ga$_2$O$_3$ interfacial reactions and kinetically favored
+Ti diffusion processes. Here we demonstrate stable Ohmic contacts for
+Ga$_2$O$_3$ devices operating up to 500-600$^{\circ}$C using ultrathin Ti
+layers with a self-limiting interfacial reaction. The ultrathin Ti layer in the
+5nm Ti / 100nm Au contact stack is designed to fully oxidize while forming an
+Ohmic contact, thereby limiting both thermodynamic and kinetic instability.
+This novel contact design strategy results in an epitaxial conductive anatase
+titanium oxide interface layer that enables low-resistance Ohmic contacts that
+are stable both under long-term continuous operation (>500 hours) at
+600$^{\circ}$C in vacuum ($\leq$ 10$^{-4}$ Torr), as well as after repeated
+thermal cycling (15 times) between room temperature and 550$^{\circ}$C in
+flowing N$_2$. This stable Ohmic contact design will accelerate the development
+of high-temperature devices by enabling research focus to shift towards
+rectifying contacts and other interfacial layers.",2304.02161v1
+2023-04-16,Earth shaped by primordial H$_2$ atmospheres,"Earth's water, intrinsic oxidation state, and metal core density are
+fundamental chemical features of our planet. Studies of exoplanets provide a
+useful context for elucidating the source of these chemical traits. Planet
+formation and evolution models demonstrate that rocky exoplanets commonly
+formed with hydrogen-rich envelopes that were lost over time. These findings
+suggest that Earth may also have formed from bodies with H$_2$-rich primary
+atmospheres. Here we use a self-consistent thermodynamic model to show that
+Earth's water, core density, and overall oxidation state can all be sourced to
+equilibrium between H$_2$-rich primary atmospheres and underlying magma oceans
+in its progenitor planetary embryos. Water is produced from dry starting
+materials resembling enstatite chondrites as oxygen from magma oceans reacts
+with hydrogen. Hydrogen derived from the atmosphere enters the magma ocean and
+eventually the metal core at equilibrium, causing metal density deficits
+matching that of Earth. Oxidation of the silicate rocks from solar-like to
+Earth-like oxygen fugacities also ensues as Si, along with H and O, alloys with
+Fe in the cores. Reaction with hydrogen atmospheres and metal-silicate
+equilibrium thus provides a simple explanation for fundamental features of
+Earth's geochemistry that is consistent with rocky planet formation across the
+galaxy.",2304.07845v1
+2023-04-18,Superconductivity up to 17 K in the high-pressure rhombohedral-I phase of ReO3: a potential oxide analogy of hydride superconductors,"As an A-site-vacant perovskite-type oxide, ReO3 undergoes sequential
+pressure-driven structural transitions associated with the rotation of ReO6
+octahedra. The rhombohedral-I phase stable in the pressure range of 12-38 GPa
+is featured by a lattice of nearly close-packed oxygen layers intercalated with
+Re cations, in reminiscent of the recently discovered superhydride
+superconductors. A combined study of first-principles calculations and
+transport measurements under high pressures enabled us to discover
+superconductivity in the rhombohedral-I phase showing a dome-shaped Tc(P) with
+a maximum Tc of 17 K at about 30 GPa. In addition to the enhanced density of
+states at the Fermi level compared to that of the ambient phase, the
+low-frequency vibrations of hexagonal-close-packed oxygen lattice significantly
+strengthen the electron-phonon coupling, which is responsible for observed
+superconductivity with a relatively high Tc. The present work thus establishes
+a rare case among oxide superconductors that the light-element oxygen lattice
+plays a crucial role in inducing superconductivity.",2304.09011v1
+2023-04-25,Effects of Oxidation on the Tribological Properties of Diamond Sliding Against Silica. Insights from Ab initio Molecular Dynamics,"Tribological phenomena such as adhesion, friction, and wear can undermine the
+functionality of devices and applications based on the diamond-silica
+interface. Controlling these phenomena is highly desirable, but difficult since
+extrinsic factors, such as the surface termination by adsorbed species, can
+deeply affect the reactivity of diamond and its resistance to wear. In this
+work, we investigate the effects of diamond oxidation by massive ab initio
+molecular dynamics simulations of silica sliding against diamond surfaces
+considering different surface orientations, O-coverages, and tribological
+conditions. Our findings reveal a dual role of oxygen that depends on coverage.
+At full coverage, the adsorbed oxygen is very effective in friction and wear
+reduction because the repulsion with the silica counter-surface prevents the
+formation of chemical bonds across the interface. At reduced coverage and high
+pressure, Si-O-C bonds are anyway established. In this situation the presence
+of oxygen results detrimental as it weakens the surface C-C bonds making the
+surface more vulnerable to wear. Indeed we observed atomic wear on the C(110)
+surface at 50% O-coverage under harsh tribological conditions. The mechanisms
+of friction reduction and atomistic wear are explained through the analysis of
+the electronic properties and surface-surface interactions. Overall, our
+accurate in silico experiments shed light into the effects of adsorbed oxygen
+on the tribological behavior of diamond and show how oxidized diamond can be
+worn by silica.",2304.12511v1
+2023-04-30,"Surface activation by electron scavenger metal nanorod adsorption on TiH2, TiC, TiN, and Ti2O3","Metal/oxide support perimeter sites are known to provide unique properties
+because the nearby metal changes the local environment on the support surface.
+In particular, the electron scavenger effect reduces the energy necessary for
+surface anion desorption, thereby contributes to activation of the (reverse)
+Mars-van Krevelen mechanism. This study investigated the possibility of such
+activation in hydrides, carbides, nitrides, and sulfides. The work functions
+(WFs) of known hydrides, carbides, nitrides, oxides, and sulfides with group 3,
+4, or 5 cations (Sc, Y, La, Ti, Zr, Hf, V, Nb, and Ta) were calculated. The WFs
+of most hydrides, carbides, and nitrides are smaller than the WF of Ag,
+implying that the electron scavenger effect may occur when late transition
+metal nanoparticles are adsorbed on the surface. The WF of oxides and sulfides
+decrease when reduced. The surface anion vacancy formation energy correlates
+well with the bulk formation energy in carbides and nitrides, while almost no
+correlation is found in hydrides because of the small range of surface hydrogen
+vacancy formation energy values. The electron scavenger effect is explicitly
+observed in nanorods adsorbed on TiH2 and Ti2O3; the surface vacancy formation
+energy decreases at anion sites near the nanorod, and charge transfer to the
+nanorod happens when an anion is removed at such sites. Activation of hydrides,
+carbides, and nitrides by nanorod adsorption and screening support materials
+through WF calculation are expected to open up a new category of supported
+catalysts.",2305.00390v1
+2023-05-02,Gate-tunable spin Hall effect in an all-light-element heterostructure: graphene with copper oxide,"Graphene is a light material for long-distance spin transport due to its low
+spin-orbit coupling, which at the same time is the main drawback to exhibit a
+sizeable spin Hall effect. Decoration by light atoms has been predicted to
+enhance the spin Hall angle in graphene while retaining a long spin diffusion
+length. Here, we combine a light metal oxide (oxidized Cu) with graphene to
+induce the spin Hall effect. Its efficiency, given by the product of the spin
+Hall angle and the spin diffusion length, can be tuned with the Fermi level
+position, exhibiting a maximum (1.8 $\pm$ 0.6 nm at 100 K) around the charge
+neutrality point. This all-light-element heterostructure shows a larger
+efficiency than conventional spin Hall materials. The gate-tunable spin Hall
+effect is observed up to room temperature. Our experimental demonstration
+provides an efficient spin-to-charge conversion system free from heavy metals
+and compatible with large-scale fabrication.",2305.01787v2
+2023-05-10,"Design, Modeling and Fabrication of Nanostructure Devices for Optoelectronic Applications","The current research work encompasses design modelling and fabrication of
+vertically aligned nanowire metal oxide semiconductor based voltage tunable
+quantum dot devices for optoelectronic applications. A novel device scheme is
+proposed for developing such VTQDs by combining the effects of nanowire
+geometry dependent structural confinement in transverse directions and the
+voltage assisted surface quantization in longitudinal direction. The formation
+of VTQDs near oxide/semiconductor interface at room temperature is predicted by
+developing a self consistent quantum electrostatic simultaneous solver. The
+photogeneration phenomenon and carrier transport in nanowire MOS based VTQD
+devices is analytically modelled by adopting non equilibrium Greens formalism
+based on second quantization field operators for incident photons and generated
+photocarriers. Engineering the combined effects of structural and electrical
+quantization has enabled a route for developing wavelength selective direct
+colour sensors with high spectral resolution. The developed NEGF based
+analytical model is further extended to obtain photocurrent which can be
+utilized for harvesting solar energy. A design window is also proposed for
+obtaining the desired values of solar cell performance parameters with the
+optimized device parameters such as, the nanowire diameter and oxide thickness.
+Finally, a patterned array of such nanowire MOS based VTQD devices is
+fabricated by employing electron beam lithography. The step like behaviour in
+capacitance voltage characteristics of such devices measured in situ within the
+FESEM chamber confirms the formation of VTQDs at room temperature. Such
+patterned nanowire MOS based VTQD devices can be utilized for the advanced
+photosensing and solar energy harvesting applications.",2305.06277v1
+2023-05-18,Indium-Tin-Oxide for High-performance Electro-optic Modulation,"Advances in opto-electronics are often led by discovery and development of
+materials featuring unique properties. Recently the material class of
+transparent conductive oxides (TCO) has attracted attention for active photonic
+devices on-chip. In particular Indium Tin Oxide (ITO) is found to have
+refractive index changes on the order of unity. This property makes it possible
+to achieve electro-optic modulation of sub-wavelength device scales, when thin
+ITO films are interfaced with optical light confinement techniques such as
+found in plasmonics; optical modes are compressed to nanometer scale to create
+strong light-matter-interactions. Here we review efforts towards utilizing this
+novel material for high-performance and ultra-compact modulation. While high
+performance metrics are achieved experimentally, there are open questions
+pertaining the permittivity modulation mechanism of ITO. Furthermore, we show
+that a footprint-saving waveguide inline cavity can enhance obtainable
+extinction-ratio to insertion-loss ratios by about one order of magnitude over
+non-cavity based version. Moreover, we offer a speed analysis that shows that
+the device is resistance limited, but not capacitance or drift-carrier limited.
+Interestingly, two bias options exist for ITO and we find that a
+side-connection enables devices that should in principle enable several hundred
+of GHz fast devices, using our routinely achievable ITO film resistivities.
+Finally, we offer a brief discuss about footprint savings of compact ITO
+modulators showing a 3-orders of magnitude smaller footprint over Silicon
+photonic MZI-based modulators.",2305.10639v1
+2023-05-21,A Critical Evaluation of a Self-Driving Laboratory for the Optimization of Electrodeposited Earth-Abundant Mixed-Metal Oxide Catalysts for the Oxygen Evolution Reaction (OER),"This work highlights the potential of earth-abundant mixed-metal oxide
+catalysts for the acid-based oxygen evolution reaction. These catalysts offer
+numerous combinations of metal-centre compositions, which can enhance catalytic
+activity and stability compared to precious-metal-based catalysts commonly used
+today. Despite substantial research in this field, there is a need for new
+methods and approaches to accelerate the exploration of these materials. In
+this study, we present a comprehensive approach to designing, developing, and
+implementing a self-driving laboratory to optimize the electrodeposition
+synthesis of amorphous mixed-metal oxide catalysts for the acidic oxygen
+evolution reaction. We particularly emphasize the development of methodologies
+to address experimental variability. We investigate crucial parameters and
+considerations when transitioning from manual bench-top synthesis and
+evaluation to automation and machine learning guided optimization. We address
+both experimental and optimization algorithm considerations in the presence of
+experimental variability. To illustrate our approach, we demonstrate the
+optimization of CoFeMnPbOx electrodeposited catalyst materials through multiple
+campaigns. Our results highlight considerations for optimizing overpotential
+and stability based on the outcomes of our experiments.",2305.12541v2
+2023-05-29,Spin current generation from an epitaxial tungsten dioxide WO$_{2}$,"We report on efficient spin current generation at room temperature in rutile
+type WO$_{2}$ grown on Al$_{2}$O$_{3}$(0001) substrate. The optimal WO$_{2}$
+film has (010)-oriented monoclinically distorted rutile structure with metallic
+conductivity due to 5$\it{d}$$^2$ electrons, as characterized by x-ray
+diffraction, electronic transport, and x-ray photoelectron spectroscopy. By
+conducting harmonic Hall measurement in Ni$_{81}$Fe$_{19}$/WO$_{2}$ bilayer, we
+estimate two symmetries of the spin-orbit torque (SOT), i.e., dampinglike (DL)
+and fieldlike ones to find that the former is larger than the latter. By
+comparison with the Ni$_{81}$Fe$_{19}$/W control sample, the observed DL SOT
+efficiency $\xi$$_{DL}$ of WO$_{2}$ (+0.174) is about two thirds of that of W
+(-0.281) in magnitude, with a striking difference in their signs. The magnitude
+of the $\xi$$_{DL}$ of WO$_{2}$ exhibits comparable value to those of widely
+reported Pt and Ta, and Ir oxide IrO$_{2}$. The positive sign of the
+$\xi$$_{DL}$ of WO$_{2}$ can be explained by the preceding theoretical study
+based on the 4$\it{d}$ oxides. These results highlight that the epitaxial
+WO$_{2}$ offers a great opportunity of rutile oxides with spintronic
+functionalities, leading to future spin-orbit torque-controlled devices.",2305.17887v3
+2023-05-31,Near-Atomic Scale Perspective on the Oxidation of Ti$_3$C$_2$T$_x$ MXenes: Insights from Atom Probe Tomography,"MXenes are a family of 2D transition metal carbides and nitrides with
+remarkable properties and great potential for energy storage and catalysis
+applications. However, their oxidation behavior is not yet fully understood,
+and there are still open questions regarding the spatial distribution and
+precise quantification of surface terminations, intercalated ions, and possible
+uncontrolled impurities incorporated during synthesis and processing. Here,
+atom probe tomography analysis of as-synthesized Ti$_3$C$_2$T$_x$ MXenes
+reveals the presence of alkali (Li, Na) and halogen (Cl, F) elements as well as
+unetched Al. Following oxidation of the colloidal solution of MXenes, it is
+observed that the alkalies enriched in TiO$_2$ nanowires. Although these
+elements are tolerated through the incorporation by wet chemical synthesis,
+they are often overlooked when the activity of these materials is considered,
+particularly during catalytic testing. This work demonstrates how the
+capability of atom probe tomography to image these elements in 3D at the
+near-atomic scale can help to better understand the activity and degradation of
+MXenes, in order to guide their synthesis for superior functional properties.",2305.19822v1
+2023-06-09,Dangling bonds as possible contributors to charge noise in silicon and silicon-germanium quantum dot qubits,"Spin qubits based on Si and Si$_{1-x}$Ge$_{x}$ quantum dot architectures
+exhibit among the best coherence times of competing quantum computing
+technologies, yet they still suffer from charge noise that limit their qubit
+gate fidelities. Identifying the origins of these charge fluctuations is
+therefore a critical step toward improving Si quantum-dot-based qubits. Here we
+use hybrid functional calculations to investigate possible atomistic sources of
+charge noise, focusing on charge trapping at Si and Ge dangling bonds (DBs). We
+evaluate the role of global and local environment in the defect levels
+associated with DBs in Si, Ge, and \sige alloys, and consider their trapping
+and excitation energies within the framework of configuration coordinate
+diagrams. We additionally consider the influence of strain and oxidation in
+charge-trapping energetics by analyzing Si and Ge$_{\rm Si}$ DBs in SiO$_2$ and
+strained Si layers in typical \sige quantum dot heterostructures. Our results
+identify that Ge dangling bonds are more problematic charge-trapping centers
+both in typical \sige alloys and associated oxidation layers, and they may be
+exacerbated by compositional inhomogeneities. These results suggest the
+importance of alloy homogeneity and possible passivation schemes for DBs in
+Si-based quantum dot qubits and are of general relevance to mitigating possible
+trap levels in other Si, Ge, and Si$_{1-x}$Ge$_{x}$-based
+metal-oxide-semiconductor stacks and related devices.",2306.06229v1
+2023-06-14,Radiation-Induced Degradation Mechanism of X-ray SOI Pixel Sensors with Pinned Depleted Diode Structure,"The X-ray Silicon-On-Insulator (SOI) pixel sensor named XRPIX has been
+developed for the future X-ray astronomical satellite FORCE. XRPIX is capable
+of a wide-band X-ray imaging spectroscopy from below 1 keV to a few tens of keV
+with a good timing resolution of a few tens of $\mu$s. However, it had a major
+issue with its radiation tolerance to the total ionizing dose (TID) effect
+because of its thick buried oxide layer due to the SOI structure. Although new
+device structures introducing pinned depleted diodes dramatically improved
+radiation tolerance, it remained unknown how radiation effects degrade the
+sensor performance. Thus, this paper reports the results of a study of the
+degradation mechanism of XRPIX due to radiation using device simulations. In
+particular, mechanisms of increases in dark current and readout noise are
+investigated by simulation, taking into account the positive charge
+accumulation in the oxide layer and the increase in the surface recombination
+velocity at the interface between the sensor layer and the oxide layer. As a
+result, it is found that the depletion of the buried p-well at the interface
+increases the dark current, and that the increase in the sense-node capacitance
+increases the readout noise.",2306.08716v1
+2023-06-15,Vibrational Anharmonicity Assisted Phase Transitions in Perovskite Oxides under Terahertz Irradiation,"Despite extensive research interests in perovskite oxides, low energy
+consumption, non-destructive and maneuverable methods for phase transition in
+perovskite oxides are still the under its exploration, and the underlying
+mechanisms remain ambiguous. Here, optical susceptibility including electronic
+and anharmonic phononic contributions is used to evaluate Gibbs free energy
+variations of $\mathrm{PbTiO}_3$ and $\mathrm{BaTiO}_3$ under terahertz
+irradiation. This corresponds to an off-resonant light-controlled phase
+transition, rather than the resonant approaches that excites hot carriers over
+electronic band or infrared-active vibrations in the phonon band. We show that
+intermediate terahertz light can trigger polarization change between
+ferroelectric orientation variants of $\mathrm{PbTiO}_3$ at room temperature
+300 K. Furthermore, the phase transition from low symmetric ferroelectric phase
+to high symmetric paraelectric structure in $\mathrm{PbTiO}_3$ can be driven by
+changing the direction and intensity of the incident light under the same
+conditions. Similar results are observed in $\mathrm{BaTiO}_3$. In detail,
+phonon spectrum and optical susceptibility are obviously modified and show
+temperature dependence, in which we show the significant effects of anharmonic
+vibration. In order to show its nonlinear optical nature, we perform an
+alternating electric field dressed ab initio molecular dynamics simulation,
+which maps the Raman-active phonon excitation under off-resonant terahertz
+irradiation.",2306.08825v1
+2023-06-22,Out-of-equilibrium charge redistribution in a copper-oxide based superconductor by time-resolved X-ray photoelectron spectroscopy,"Charge-transfer excitations are of paramount importance for understanding the
+electronic structure of copper-oxide based high-temperature superconductors. In
+this study, we investigate the response of a
+Bi$_2$Sr$_2$CaCu$_2$O$_{\mathrm{8}+ \delta}$ crystal to the charge
+redistribution induced by an infrared ultrashort pulse. Element-selective
+time-resolved core-level photoelectron spectroscopy with a high energy
+resolution allows disentangling the dynamics of oxygen ions with different
+coordination and bonds thanks to their different chemical shifts. Our
+experiment shows that the O\,$1s$ component arising from the Cu-O planes is
+significantly perturbed by the infrared light pulse. Conversely, the apical
+oxygen, also coordinated with Sr ions in the Sr-O planes, remains unaffected.
+This result highlights the peculiar behavior of the electronic structure of the
+Cu-O planes. It also unlocks the way to study the out-of-equilibrium electronic
+structure of copper-oxide-based high-temperature superconductors by identifying
+the O\,$1s$ core-level emission originating from the oxygen ions in the Cu-O
+planes. This ability could be critical to gain information about the
+strongly-correlated electron ultrafast dynamical mechanisms in the Cu-O plane
+in the normal and superconducting phases.",2306.12905v1
+2023-06-26,Microscopic conductivity of passive films on ferritic stainless steel for hydrogen fuel cells,"Hydrogen fuel cells offer a clean and sustainable energy conversion solution.
+The bipolar separator plate, a critical component in fuel cells, plays a vital
+role in preventing reactant gas cross-contamination and facilitating efficient
+ion transport in a fuel cell. High chromium ferritic stainless steel with an
+artificially formed thin chromium oxide passive film has recently gained
+attention due to its superior electrical conductivity and corrosion resistance,
+making it a suitable material for separators. In this study, we investigate the
+microscopic electrical conductivity of the intrinsic passive oxide film on such
+ferritic stainless steel. Through advanced surface characterization techniques
+such as current sensing atomic force microscopy and scanning tunneling
+microscopy/spectroscopy, we discover highly conductive regions within the film
+that vary depending on location. These findings provide valuable insights into
+the behavior of the passive oxide film in fuel cells. By understanding the
+microscopic electrical properties, we can enhance the design and performance of
+separator materials in hydrogen fuel cells. Ultimately, this research
+contributes to a broader understanding of separator materials and supports the
+wider application of hydrogen fuel cells.",2306.14513v1
+2023-07-04,Self-Supervised Deep Learning for Model Correction in the Computational Crystallography Toolbox,"The Computational Crystallography Toolbox (CCTBX) is open-source software
+that allows for processing of crystallographic data, including from serial
+femtosecond crystallography (SFX), for macromolecular structure determination.
+We aim to use the modules in CCTBX to determine the oxidation state of
+individual metal atoms in a macromolecule. Changes in oxidation state are
+reflected in small shifts of the atom's X-ray absorption edge. These energy
+shifts can be extracted from the diffraction images recorded in serial
+femtosecond crystallography, given knowledge of a forward physics model.
+However, as the diffraction changes only slightly due to the absorption edge
+shift, inaccuracies in the forward physics model make it extremely challenging
+to observe the oxidation state. In this work, we describe the potential impact
+of using self-supervised deep learning to correct the scientific model in CCTBX
+and provide uncertainty quantification. We provide code for forward model
+simulation and data analysis, built from CCTBX modules, at
+https://github.com/gigantocypris/SPREAD , which can be integrated with machine
+learning. We describe open questions in algorithm development to help spur
+advances through dialog between crystallographers and machine learning
+researchers. New methods could help elucidate charge transfer processes in many
+reactions, including key events in photosynthesis.",2307.01901v1
+2023-07-13,Metal Oxide-based Gas Sensor Array for the VOCs Analysis in Complex Mixtures using Machine Learning,"Detection of Volatile Organic Compounds (VOCs) from the breath is becoming a
+viable route for the early detection of diseases non-invasively. This paper
+presents a sensor array with three metal oxide electrodes that can use machine
+learning methods to identify four distinct VOCs in a mixture. The metal oxide
+sensor array was subjected to various VOC concentrations, including ethanol,
+acetone, toluene and chloroform. The dataset obtained from individual gases and
+their mixtures were analyzed using multiple machine learning algorithms, such
+as Random Forest (RF), K-Nearest Neighbor (KNN), Decision Tree, Linear
+Regression, Logistic Regression, Naive Bayes, Linear Discriminant Analysis,
+Artificial Neural Network, and Support Vector Machine. KNN and RF have shown
+more than 99% accuracy in classifying different varying chemicals in the gas
+mixtures. In regression analysis, KNN has delivered the best results with R2
+value of more than 0.99 and LOD of 0.012, 0.015, 0.014 and 0.025 PPM for
+predicting the concentrations of varying chemicals Acetone, Toluene, Ethanol,
+and Chloroform, respectively in complex mixtures. Therefore, it is demonstrated
+that the array utilizing the provided algorithms can classify and predict the
+concentrations of the four gases simultaneously for disease diagnosis and
+treatment monitoring.",2307.06556v2
+2023-07-18,Oxidation kinetics and non-Marcusian charge transfer in dimensionally confined semiconductors,"Electrochemical reactions represent essential processes in fundamental
+chemistry that foster a wide range of applications. Although most
+electrochemical reactions in bulk substances can be well described by the
+classical Marcus-Gerischer charge transfer theory, the realistic reaction
+character and mechanism in dimensionally confined systems remain unknown. Here,
+we report the multiparametric survey on the kinetics of lateral photooxidation
+in structurally identical WS2 and MoS2 monolayers, where electrochemical
+oxidation occurs at the atomically thin monolayer edges. The oxidation rate is
+correlated quantitatively with various crystallographic and environmental
+parameters, including the density of reactive sites, humidity, temperature, and
+illumination fluence. In particular, we observe distinctive reaction barriers
+of 1.4 and 0.9 eV for the two structurally identical semiconductors and uncover
+an unusual non-Marcusian charge transfer mechanism in these dimensionally
+confined monolayers due to the limit in reactant supplies. A scenario of band
+bending is proposed to explain the discrepancy in reaction barriers. These
+results add important knowledge into the fundamental electrochemical reaction
+theory in low-dimensional systems.",2307.08957v1
+2023-08-07,The cycling mechanism of manganese-oxide cathodes in zinc batteries: A theory-based approach,"Zinc-based batteries offer good volumetric energy densities and are
+compatible with environmentally friendly aqueous electrolytes. Zinc-ion
+batteries (ZIBs) rely on a lithium-ion-like Zn$^{2+}$-shuttle, which enables
+higher roundtrip efficiencies and better cycle life than zinc-air batteries.
+Manganese-oxide cathodes in near-neutral zinc sulfate electrolytes are the most
+prominent candidates for ZIBs. Zn$^{2+}$-insertion, H$^+$-insertion, and
+Mn$^{2+}$-dissolution are proposed to contribute to the charge-storage
+mechanism. During discharge and charge, two distinct phases are observed.
+Notably, the pH-driven precipitation of zinc-sulfate-hydroxide is detected
+during the second discharge phase. However, a complete and consistent
+understanding of the two-phase mechanism of these ZIBs is still missing. This
+paper presents a continuum full cell model supported by DFT calculations to
+investigate the implications of these observations. We integrate the
+complex-formation reactions of near-neutral aqueous electrolytes into the
+battery model and, in combination with the DFT calculations, draw a consistent
+picture of the cycling mechanism. We investigate the interplay between
+electrolyte pH and reaction mechanisms at the manganese-oxide cathodes and
+identify the dominant charge-storage mechanism. Our model is validated with
+electrochemical cycling data, cyclic voltammograms, and in-situ pH measurments.
+This allows us to analyse the influence of cell design and electrolyte
+composition on cycling and optimize the battery performance.",2308.03352v1
+2023-08-22,The prototypical organic-oxide interface: intra-molecular resolution of sexiphenyl on In$_2$O$_3$(111),"The performance of an organic-semiconductor device is critically determined
+by the geometric alignment, orientation, and ordering of the organic molecules.
+While an organic multilayer eventually adopts the crystal structure of the
+organic material, the alignment and configuration at the interface with the
+substrate/electrode material is essential for charge injection into the organic
+layer. This work focuses on the prototypical organic semiconductor
+para-sexiphenyl (6P) adsorbed on In$_2$O$_3$(111), the thermodynamically most
+stable surface of the material that the most common transparent conducting
+oxide, indium tin oxide (ITO) is based on. The onset of nucleation and
+formation of the first monolayer are followed with atomically-resolved scanning
+tunneling microscopy (STM) and non-contact atomic force microscopy (nc-AFM).
+Annealing to 200$^\circ$C provides sufficient thermal energy for the molecules
+to orient themselves along the high-symmetry directions of the surface, leading
+to a single adsorption site. The AFM data suggests a twisted adsorption
+geometry. With increasing coverage, the 6P molecules first form a loose network
+with poor long-range order. Eventually the molecules re-orient and form an
+ordered monolayer. This first monolayer has a densely packed, well-ordered
+(2$\times$1) structure with one 6P per In$_2$O$_3$(111) substrate unit cell,
+i.e., a molecular density of 5.64$\times$10$^{13}$ cm$^{-2}$.",2308.11550v1
+2023-08-23,"A study of Pt, Rh, Ni and Ir dispersion on anatase TiO2(101) and the role of water","Understanding how metal atoms are stabilized on metal oxide supports is
+important for predicting the stability of single-atom catalysts. In this study,
+we use scanning tunnelling microscopy (STM) and x-ray photoelectron
+spectroscopy (XPS) to investigate four catalytically active metals - Platinum,
+Rhodium, Nickel and Iridium - on the anatase TiO2(101) surface. The metals were
+vapor deposited at room temperature in ultrahigh vacuum (UHV) conditions, and
+also with a background water pressure of 2x10-8 mbar. Pt and Ni exist as a
+mixture of adatoms and nanoparticles in UHV at low coverage, with the adatoms
+immobilized at defect sites. Water has no discernible effect on the Pt
+dispersion, but significantly increases the amount of Ni single atoms. Ir is
+highly dispersed, but sinters to nanoparticles in the water vapor background
+leading to the formation of large clusters at step edges. Rh forms clusters on
+the terrace of anatase TiO2(101) irrespective of the environment. We conclude
+that introducing defect sites into metal oxide supports could be a strategy to
+aid the dispersion of single atoms on metal-oxide surfaces, and that the
+presence of water should be taken into account in the modelling of single-atom
+catalysts.",2308.11973v1
+2023-09-29,Is the Mg-related GaN blue luminescence deep-level an MgO surface state?,"Mg is currently the only p-type dopant in technological use in GaN. Its
+incorporation into the GaN lattice is difficult. It requires a thermal
+treatment that only partially activates the Mg. To achieve moderate p-type
+doping requires high doses of Mg that mostly remain inactive. High p-type
+doping is thus typically achieved at the cost of certain lattice distortion and
+the creation of defects. Using low-temperature surface photovoltage
+spectroscopy, we obtain a wide spectrum of optical transitions within the
+bandgap of Mg-doped GaN. The results reveal an optical transition from the
+valence band into a deep trap around 0.49 eV above the valence band, along with
+what appears to be a complimentary transition from the same trap into the
+conduction band observed at 2.84 eV (coinciding with the energy of the famous
+Mg-related GaN blue luminescence). The similar shape of the spectra, their
+complimentary energies within the GaN gap and their opposite nature (hole vs.
+electron trap) appear to be more than a coincidence suggesting that this is an
+Mg-related surface state. The density of charge we calculate for this surface
+state is about 2x1012 cm-2. We suggest that these small amounts of
+surface-segregated Mg partially oxidize during the growth and further oxidize
+during the consecutive Mg-activation heat treatment. This minute quantity of
+oxidized surface Mg should be about enough to form an Mg-related surface state.
+Etching the GaN with H3PO4 is shown to affect the photovoltage at the
+blue-luminescence-related energy. Finally, we show that pure MgO powder
+produces the same blue luminescence even at the absolute absence of GaN.",2309.17212v2
+2023-10-09,"Impact of interface traps on charge noise, mobility and percolation density in Ge/SiGe heterostructures","Hole spins in Ge/SiGe heterostructure quantum dots have emerged as promising
+qubits for quantum computation. The strong spin-orbit coupling (SOC),
+characteristic of heavy-hole states in Ge, enables fast and all-electrical
+qubit control. However, SOC also increases the susceptibility of spin qubits to
+charge noise. While qubit coherence can be significantly improved by operating
+at sweet spots with reduced hyperfine or charge noise sensitivity, the latter
+ultimately limits coherence, underlining the importance of understanding and
+reducing charge noise at its source. In this work, we study the voltage-induced
+hysteresis commonly observed in SiGe-based quantum devices and show that the
+dominant charge fluctuators are localized at the semiconductor-oxide interface.
+By applying increasingly negative gate voltages to Hall bar and quantum dot
+devices, we investigate how the hysteretic filling of interface traps impacts
+transport metrics and charge noise. We find that the gate-induced accumulation
+and trapping of charge at the SiGe-oxide interface leads to an increased
+electrostatic disorder, as probed by transport measurements, as well as the
+activation of low-frequency relaxation dynamics, resulting in slow drifts and
+increased charge noise levels. Our results highlight the importance of a
+conservative device tuning strategy and reveal the critical role of the
+semiconductor-oxide interface in SiGe heterostructures for spin qubit
+applications.",2310.05902v1
+2023-10-18,Simulating high-pressure surface reactions with molecular beams,"Using a reactive molecular beam with high kinetic energy ($E_{kin}$) it is
+possible to speed gas-surface reactions involving high activation barriers
+($E_{act}$), which would require elevated pressures ($P_0$) if a random gas
+with a Maxwell-Boltzmann distribution is used. By simply computing the number
+of molecules that overcome the activation barrier in a random gas at $P_0$ and
+in a molecular beam at $E_{kin}$=$E_{act}$, we establish an $E_{kin}$-$P_0$
+equivalence curve, through which we postulate that molecular beams are ideal
+tools to investigate gas-surface reactions that involve high activation
+energies. In particular, we foresee the use of molecular beams to simulate gas
+surface reactions within the industrial-range ($>$ 10 bar) using
+surface-sensitive Ultra-High Vacuum (UHV) techniques, such as X-ray
+photoemission spectroscopy (XPS). To test this idea, we revisit the oxidation
+of the Cu(111) surface combining O$_2$ molecular beams and XPS experiments. By
+tuning the kinetic energy of the O$_2$ beam in the range 0.24-1 eV we achieve
+the same sequence of surface oxides obtained in Ambient Pressure Photoemission
+(AP-XPS) experiments, in which the Cu(111) surface was exposed to a random
+O$_2$ gas up to 1 mbar. We observe the same surface oxidation kinetics as in
+the random gas, but with a much lower dose, close to the expected value derived
+from the equivalence curve.",2310.12041v1
+2023-11-01,Rational design of acid stable oxide catalysts for OER with OC22,"The efficiency of $H_2$ production via water electrolysis is typically
+limited to the sluggish oxygen evolution reaction (OER). As such, significant
+emphasis has been placed upon improving the rate of OER through the anode
+catalyst. More recently, the Open Catalyst 2022 (OC22) has provided a large
+dataset of density functional theory (DFT) calculations for OER intermediates
+on the surfaces of oxides. When coupled with state-of-the-art graph neural
+network models, total energy predictions can be achieved with a mean absolute
+error as low as of 0.22 eV. In this work, we interpolated a database of the
+total energy predictions for all slabs and OER surface intermediates for 4,119
+oxide materialas in the original OC22 dataset using pre-trained models from the
+OC22 framework. This database includes all terminations of all facets up to a
+maximum Miller index of 1 with adsorption configurations for $O^*$ and $OH^*$.
+To demonstrate the full utility of this database, we constructed a flexible
+screening framework to identify viable candidate anode catalysts under a bulk
+and nanoscale regime for OER by assessing the price, thermodynamic stability,
+and resistance to corrosion, surface stability, and overpotential. Finally we
+verified the overpotentials and reaction energies of the final candidate
+catalysts using DFT. From our assessment, we were able to identify 48 and 69
+viable candidates for OER under the bulk and nanoscale regime respectively.",2311.00784v2
+2023-11-27,The influence of pinholes and weak-points in aluminium-oxide Josephson junctions,"Josephson junctions are the key components used in superconducting qubits for
+quantum computing. The advancement of quantum computing is limited by a lack of
+stability and reproducibility of qubits which ultimately originates in the
+amorphous tunnel barrier of the Josephson junctions and other material
+imperfections. Pinholes in the junction have been suggested as one of the
+possible contributors to these instabilities, but evidence of their existence
+and the effect they might have on transport is unclear. We use molecular
+dynamics to create three-dimensional atomistic models to describe Al-AlOx-Al
+tunnel junctions, showing that pinholes form when oxidation of the barrier is
+incomplete. Following this we use the atomistic model and simulate the
+electronic transport properties for tunnel junctions with different barrier
+thicknesses using the non-equilibrium Green's function formalism. We observe
+that pinholes may contribute to excess quasiparticle current flow in Al-AlOx-Al
+tunnel junctions with thinner barriers, and in thicker barriers we observe
+weak-points which facilitate leakage currents even when the oxide is
+continuous. We find that the disordered nature of the amorphous barrier results
+in significant variations in the transport properties. Additionally, we
+determine the current-phase relationship for our atomistic structures,
+confirming that devices with pinholes and weak-points cause a deviation from
+the ideal sinusoidal Josephson relationship.",2311.15560v2
+2023-11-27,Evaluation of microscale crystallinity modification induced by laser writing on Mn3O4 thin films,"Defining microstructures and managing local crystallinity allow the
+implementation of several functionalities in thin film technology. The use of
+ultrashort Bessel beams for bulk crystallinity modification has garnered
+considerable attention as a versatile technique for semiconductor materials,
+dielectrics, or metal oxide substrates. The aim of this work is the
+quantitative evaluation of the crystalline changes induced by ultrafast laser
+micromachining on manganese oxide thin films using micro-Raman spectroscopy.
+Pulsed Bessel beams featured by a 1 micrometer-sized central core are used to
+define structures with high spatial precision. The dispersion relation of Mn3O4
+optical phonons is determined by considering the conjunction between X-ray
+diffraction characterization and the phonon localization model. The asymmetries
+in Raman spectra indicate phonon localization and enable a quantitative tool to
+determine the crystallite size at micrometer resolution. The results indicate
+that laser-writing is effective in modifying the low-crystallinity films
+locally, increasing crystallite sizes from ~8 nm up to 12 nm, and thus
+highlighting an interesting approach to evaluate laser-induced structural
+modifications on metal oxide thin films.",2311.16061v1
+2023-12-22,FeMnNiAlCr High Entropy Alloys with High-Efficiency Surface Oxide Solar Absorbers for Concentrating Solar Power Systems,"High entropy alloys (HEAs) have attracted substantial interest in recent
+years. Thus far, most investigations have focused on their applications as
+structural materials rather than functional materials. In this paper, we show
+that FeMnNiAlCr HEAs can potentially be applied as both a structural and
+functional material for high-efficiency concentrated solar thermal power (CSP)
+systems working at >700 degrees C. The HEA itself would be used in
+high-temperature tubing to carry working fluids, while its surface oxide would
+act as a high-efficiency solar thermal absorber. These HEAs have demonstrated
+yield strengths 2-3x greater than that of stainless steel at 700 degrees C and
+a creep lifetime >800 h at 700 degrees C under a typical CSP tubing mechanical
+load of 35 MPa. Their Mn-rich surface oxides maintain a high optical-to-thermal
+conversion efficiency of ~87% under 1000x solar concentration for 20 simulated
+day-night thermal cycles between 750 degrees C and environmental temperature.
+These HEAs have also sustained immersion in unpurified bromide molten salts for
+14 days at 750{\deg}C with <2% weight loss, in contrast to 70% weight loss from
+a 316 stainless steel reference. The simultaneous achievement of promising
+mechanical, optical, and thermochemical properties in this FeMnNiAlCr system
+opens the door to new applications of HEAs in solar energy harvesting.",2312.15076v1
+2024-01-02,Operando Plasma-XPS for Process Monitoring: Hydrogenation of Copper Oxide Confined Under h-BN Case Study,"We demonstrate that ambient pressure x-ray photoelectron spectroscopy (APXPS)
+can be used for in situ studies of dynamic changes in surface chemistry in a
+plasma environment. Hexagonal boron nitride (h-BN) was used in this study as a
+model system since it exhibits a wide array of unique chemical, optical, and
+electrical properties that make it a prospective material for advanced
+electronics. To better understand the stability and surface chemistry of h-BN
+during plasma-assisted processing, we used polycrystalline Cu foils with
+single-layer h-BN, grown via chemical vapor deposition (CVD), and tracked in
+real-time the plasma-induced reduction of the underlying Cu oxide using APXPS
+equipped with 22 kHz 75 W discharge plasma source operating at 13 Pa. Residual
+gas analysis (RGA) mass-spectra were concurrently collected during plasma-XPS
+to track reaction products formed during plasma exposure. A clear reduction of
+CuxO is seen, while an h-BN layer remains intact, suggesting H radical species
+can attack the exposed and h-BN-covered Cu oxide patches and partially reduce
+the underlying substrate. In addition to the demonstration and discussion of
+plasma-XPS capabilities, our results indicate the h-BN encapsulated metallic Cu
+interface might be repaired without significantly damaging the overlaying h-BN,
+which is of practical importance for the development of h-BN encapsulated
+devices and interfaces",2401.01434v1
+2024-01-26,Solvent-Free High-Temperature Capillary Stamping of Stimuli-Responsive Polymers: Wettability Management by Orthogonal Substrate Functionalization,"The wettability of surfaces determines their antifouling, antifogging,
+anti-icing, and self-cleaning properties as well as their usability for
+sensing, oil-water separation, water collection, and water purification.
+Solvent-free high-temperature capillary stamping of stimuli-responsive polymers
+yielding arrays of stimuli-responsive polymer microdots on differently modified
+substrates enables the flexible generation of switchable surfaces with
+different water contact angles (WCAs). Potential problems associated with the
+deposition of polymer solutions, such as the handling of volatile organic
+solvents, phase separation induced by solvent evaporation, and
+capillarity-driven flow processes, are circumvented. We used composite stamps
+with topographically patterned contact surfaces consisting of metallic nickel
+cores and porous MnO2 coatings taking up the stimuli-responsive polymers. The
+short transport paths from the MnO2 contact layers to the counterpart
+substrates enabled the stamping of polymer melts containing components impeding
+flow, such as carbon nanotubes (CNTs). Thus-obtained arrays of polymer-CNT
+hybrid microdots prevent problems associated with continuous coatings including
+delamination and crack propagation. Moreover, the range within which the
+properties of the stamped stimuli-responsive polymer microdots are switchable
+can be tuned by orthogonal substrate modification. As an example, we stamped
+hybrid microdots consisting of poly(2-(methacryloyloxy)ethyl
+ferrocenecarboxylate) (PFcMA) and CNTs onto indium tin oxide (ITO) substrates.
+Coating the ITO substrates with a poly(ethylene oxide)-terminated silane
+shifted the WCAs obtained by switching the PFcMA between its oxidized and
+reduced states by nearly 50{\deg}.",2401.14974v1
+2024-01-29,Scavenging effect on plasma oxidized Gd$_2$O$_3$ grown by high pressure sputtering on Si and InP substrates,"In this work, we analyze the scavenging effect of titanium gates on metal
+insulator semiconductor capacitors composed of gadolinium oxide as dielectric
+material deposited on Si and InP substrates. The Gd$_2$O$_3$ film was grown by
+high pressure sputtering from a metallic target followed by an in situ plasma
+oxidation. The thickness of the Ti film was varied between 2.5 and 17 nm and
+was capped with a Pt layer. For the devices grown on Si, a layer of 5 nm of Ti
+decreases the capacitance equivalent thickness from 2.3 to 1.9 nm without
+compromising the leakage current (1e-4 A cm$^{-2}$ at Vgate equal to 1 V).
+Thinner Ti has little impact on device performance, while 17 nm of Ti produces
+excessive scavenging. For InP capacitors, the scavenging effect is also
+observed with a decrease in the capacitance equivalent thickness from 2.5 to
+1.9 nm (or an increase in the accumulation capacitance after the annealing from
+1.4 to 1.7-1.8 uF cm$^{-2}$). The leakage current density remains under 1e-2 A
+cm$^{-2}$ at Vgate equal to 1.5 V. For these devices, a severe flatband voltage
+shift with frequency is observed. This can be explained by a very high
+interface trap state density (in the order of 1e13-1e14 eV$^{-1}$ cm$^{-2}$).",2401.17333v1
+2024-03-06,Systematic Improvement of Quantum Monte Carlo Calculations in Transition Metal Oxides: sCI-Driven Wavefunction Optimization for Reliable Band Gap prediction,"Accurate determination of electronic properties of correlated oxides remains
+a significant challenge for computational theory. Traditional Hubbard-corrected
+density functional theory (DFT+U) frequently encounters limitations in
+precisely capturing electron correlation, particularly when predicting band
+gaps. We introduce a systematic methodology to enhance the accuracy of
+diffusion Monte Carlo (DMC) simulations for both ground and excited states,
+focusing on LiCoO$_2$ as a case study. By employing a selected CI (sCI)
+approach, we demonstrate the capability to optimize wavefunctions beyond the
+constraints of single-reference DFT+U trial wavefunctions. We show that the sCI
+framework enables accurate prediction of band gaps in LiCoO$_2$, closely
+aligning with experimental values and substantially improving upon traditional
+computational methods. The study uncovers a nuanced mixed state of $t_{2g}$ a
+$e_g$ orbitals at the band edges that is not captured by conventional
+single-reference methods, further elucidating the limitations of PBE+U in
+describing $d$-$d$ excitations. Our findings advocate for the adoption of
+beyond-DFT methodologies, such as sCI, to capture the essential physics of
+excited state wavefunctions in strongly correlated materials. The improved
+accuracy in band gap predictions and the ability to generate more reliable
+trial wavefunctions for DMC calculations underscore the potential of this
+approach for broader applications in the study of correlated oxides. This work
+not only provides a pathway for more accurate simulations of electronic
+structures in complex materials but also suggests a framework for future
+investigations into the excited states of other challenging systems.",2403.03466v2
+2024-03-25,One-step architecture of bifunctional petal-like oxygen-deficient NiAl-LDHs nanosheets for high-performance hybrid supercapacitors and urea oxidation,"Nickel-based layered double hydroxides (LDHs) are promising electrode
+materials in the fields of energy storage (supercapacitors) and conversion
+(urea oxidation). The rational construction of atomic and electronic structure
+is crucial for nickel-based LDHs to realize their satisfactory electrochemical
+performance. Herein, we report a facile, ecofriendly, one-step synthesis
+process to construct petal-like oxygen-deficient NiAl-LDH nanosheets for hybrid
+super-capacitors (HSCs) and urea oxidation reaction (UOR). The asprepared
+NiAl-LDH nanosheets with rich oxygen vacancies possess a large specific surface
+area of 216.6 m2 g-1 and a desirable electronic conductivity of 3.45 * 10-4 S
+cm-1 to deliver an ultra-high specific capacitance of 2801 F g-1 (700 C g-1) at
+1 A g-1. Furthermore, high specific energy of 50.0 W h kg-1 at 400 W kg-1 and
+excellent cycle stability with 91% capacitance retention after 10,000 cycles
+are achieved by the NiAl-LDHs/CFP (carbon fiber paper) (+)//YP-80F (a
+commercial activated carbon) (-) HSC. Besides, NiAl-LDH nanosheets also work as
+an efficient electrocatalyst for UOR, which only requires 1.42 V vs. reversible
+hydrogen electrode to drive 10 mA cm-2 in 1 mol L-1 KOH with 0.33 mol L-1 urea.
+This remarkable performance is superior to most reported values of previous
+candidates owing to the thin structure of NiAl-LDH nanosheets for exposing more
+active sites and abundant oxygen vacancies. In addition, various reaction
+parameters are investigated to optimize the electrochemical performance. In
+general, this work paves a new way for the architecture of multifunctional
+nanostructured energy materials.",2403.17038v1
+2024-04-05,Reliable operation in high-mobility indium oxide thin film transistors,"Transparent oxide semiconductors (TOSs) based thin-film transistors (TFTs)
+that exhibit higher field effect mobility (uFE) are highly required toward the
+realization of next-generation displays. Among numerous types of TOS-TFTs,
+In2O3-based TFTs are the front-running candidate because they exhibit the
+highest uFE ~100 cm2/Vs. However, the device operation of In2O3 TFTs is
+unreliable; a large voltage shift occurs especially when negative gate bias is
+applied due to adsorption/desorption of gas molecules. Although passivation of
+the TFTs is used to overcome such instability, previously proposed passivation
+materials did not improve the reliability. Here, we show that the In2O3 TFTs
+passivated with Y2O3 and Er2O3 films are highly reliable and do not show
+threshold voltage shifts when applying gate bias. We applied positive and
+negative gate bias to the In2O3 TFTs passivated with various insulating oxides
+and found that only the In2O3 TFTs passivated with Y2O3 and Er2O3 films did not
+exhibit threshold voltage shifts. We observed that only the Y2O3 grew
+heteroepitaxially on the In2O3 crystal. This would be the origin of the high
+reliability of the In2O3 TFTs passivated with Y2O3 and Er2O3 films. This
+finding accelerates the development of next-generation displays using
+high-mobility In2O3 TFTs.",2404.03856v1
+2024-04-08,Negative Photo Conductivity Triggered with Visible Light in Wide Bandgap Oxide-Based Optoelectronic Crossbar Memristive Array for Photograph Sensing and Neuromorphic Computing Applications,"Photoresponsivity studies of wide-bandgap oxide-based devices have emerged as
+a vibrant and popular research area. Researchers have explored various material
+systems in their quest to develop devices capable of responding to
+illumination. In this study, we engineered a mature wide bandgap oxide-based
+bilayer heterostructure synaptic memristor to emulate the human brain for
+applications in neuromorphic computing and photograph sensing. The device
+exhibits advanced electric and electro-photonic synaptic functions, such as
+long-term potentiation (LTP), long-term depression (LTD), and paired pulse
+facilitation (PPF), by applying successive electric and photonic pulses.
+Moreover, the device exhibits exceptional electrical SET and photonic RESET
+endurance, maintaining its stability for a minimum of 1200 cycles without any
+degradation. Density functional theory calculations of the band structures
+provide insights into the conduction mechanism of the device. Based on this
+memristor array, we developed an autoencoder and convolutional neural network
+for noise reduction and image recognition tasks, which achieves a peak
+signal-to-noise ratio of 562 and high accuracy of 84.23%, while consuming lower
+energy by four orders of magnitude compared with the Tesla P40 GPU. This
+groundbreaking research not only opens doors for the integration of our device
+into image processing but also represents a significant advancement in the
+realm of in-memory computing and photograph sensing features in a single cell.",2404.05701v1
+1993-09-09,Effective t-J Hamiltonian for the Copper Oxides,"Starting from the Emery model, which is assumed to describe the copper oxygen
+planes, and including direct oxygen hopping matrix elements, we have been able
+to derive the effective t-J Hamiltonian for the copper orbitals using the
+Linked Cluster Expansion Method up to fourth order in the hybridization matrix
+element.",9309008v2
+1996-02-28,Static and Dynamic Spin Structure Factors of Frustrated Heisenberg Antiferromagnet,"Using the modified spin-wave theory we calculate static and dynamic spin
+structure factors in spin-liquid state of the J1-J2 model. The spectrum of
+excitations in the vector channel is discussed. The developed technique can
+also be applied to the t-J model describing copper oxide superconductors.",9602150v1
+1996-11-06,Integer filling metal insulator transitions in the degenerate Hubbard model,"We obtain exact numerical solutions of the degenerate Hubbard model in the
+limit of large dimensions (or large lattice connectivity). Successive
+Mott-Hubbard metal insulator transitions at integer fillings occur at
+intermediate values of the interaction and low enough temperature in the
+paramagnetic phase. The results are relevant for transition metal oxides with
+partially filled narrow degenerate bands.",9611045v1
+1997-01-31,Hole Photoproduction in Insulating Copper Oxide,"To explain the experimental spectra for angle resolved photoemission we
+consider a modified t-J model. The modified model includes next nearest (t')
+and next next nearest (t'') hopping as well as Hubbard model corrections to the
+spectral weights. A Dyson equation which relates the single hole Green's
+functions for a given pseudospin and given spin is derived and is compared to
+experimental results.",9702002v1
+1997-03-12,Only Fermi-Liquids are Metals,"Any singular deviation from Landau Fermi-liquid theory appears to lead, for
+arbitrarily small concentration of impurities coupling to a non-conserved
+quantity, to a vanishing density of states at the chemical potential and
+infinite resistivity as temperature approaches zero. Applications to
+copper-oxide metals including the temperature dependence of the anisotropy in
+resistivity, and to other cases of non Fermi-liquids are discussed.",9703122v1
+1998-02-21,Quantum Mott transition in a silicon quantum dot,"Considering a double-barrier structure formed by a silicon quantum dot
+covered by natural oxide, we derive simple conditions for the conductance of
+the dot to become a step-like function of the number of doping atoms inside the
+dot, with negligible dependence on the actual position of the dopants. The
+found conditions are feasible in experimentally available structures.",9802227v1
+1998-04-29,Stability of Solid State Reaction Fronts,"We analyze the stability of a planar solid-solid interface at which a
+chemical reaction occurs. Examples include oxidation, nitridation, or silicide
+formation. Using a continuum model, including a general formula for the
+stress-dependence of the reaction rate, we show that stress effects can render
+a planar interface dynamically unstable with respect to perturbations of
+intermediate wavelength.",9804321v1
+1998-08-27,A Progress Report on the SO(5) Theory of High T_c Superconductivity,"In this talk I give a brief update on the recent progress in the SO(5) theory
+of high T_c superconductivity (Science, 275: 1089,1997). Reviewed topics
+include SO(5) ladders, the unification of BCS and SDW quasi-particles in the
+SO(5) theory and the microscopic origin of the condensation energy.",9808309v1
+1999-06-09,Stripe Structures and the Berry-Phase Connection: Concept of Geometric Energy,"Electronic states of an $e_g$ electron are calculated in the system composed
+of two MnO$_6$ octahedra with the inclusion of the Berry phase acquired by
+parallel transport. Based on this calculation, a comment is made on the
+controversy between ``Wigner-crystal'' and ``paired-stripe'' models for the the
+insulating charge-ordered manganese oxides.",9906128v1
+2002-07-04,Inversion of ARPES measurements in high Tc cuprates,"Recent energy dispersion measurements in several families of the hole-doped
+copper oxides have revealed a kink in the energy vs. momentum relation. These
+have tentatively been identified as due to electron phonon coupling. We invert
+this data directly to determine the bosonic spectral function; the kink gives
+rise to a singular function in the phonon energy region.",0207145v2
+2003-03-03,Nonlinear Effects in Site Blocking Induced Oscillations,"Higher order nonlinear effects of site blocking, which induces oscillations
+in the Monte Carlo simulation of CO oxidation, are outlined here. It is shown
+that the rate equations which include these effects exhibit a supercritical
+Hopf bifurcation in parameter domains where Monte Carlo simulations lead to
+oscillations.",0303019v1
+2003-08-27,Intrinsic and extrinsic inhomogeneities in mixed-valence manganites,"It is suggested that extrinsic inhomogeneities in mixed-valence manganites
+deserve more attention and they should be taking into account on equal footing
+with hypothetical phase separation while examinating experimental data and
+developing the theoretical models of influence of stoichiometric and other
+types of inhomogeneities on properties of these and other transition-metal
+oxides.",0308571v1
+2003-12-03,Electron-phonon interaction in cuprate-oxide superconductors,"We propose a novel electron-phonon interaction arising from the modulation of
+the superexchange interaction by phonons. It is enhanced by spin and
+superconducting fluctuations, which are developed mainly because of the
+superexchange interaction. It must be responsible for the softening of phonons
+and kinks in the dispersion relation of quasi-particles. However, the
+superexchange interaction must be mainly responsible for the formation of
+Cooper pairs.",0312085v1
+2004-10-27,Scaling of the superfluid density in high-temperature superconductors,"A scaling relation \rho_s \simeq 35\sigma_{dc}T_c has been observed in the
+copper-oxide superconductors, where \rho_s is the strength of the
+superconducting condensate, T_c is the critical temperature, and \sigma_{dc} is
+the normal-state dc conductivity close to T_c. This scaling relation is
+examined within the context of a clean and dirty-limit BCS superconductor.
+These limits are well established for an isotropic BCS gap 2\Delta and a
+normal-state scattering rate 1/\tau; in the clean limit 1/\tau \ll 2\Delta, and
+in the dirty limit 1/\tau > 2\Delta. The dirty limit may also be defined
+operationally as the regime where \rho_s varies with 1/\tau. It is shown that
+the scaling relation \rho_s \propto \sigma_{dc}T_c is the hallmark of a BCS
+system in the dirty-limit. While the gap in the copper-oxide superconductors is
+considered to be d-wave with nodes and a gap maximum \Delta_0, if 1/\tau >
+2\Delta_0 then the dirty-limit case is preserved. The scaling relation implies
+that the copper-oxide superconductors are likely to be in the dirty limit, and
+that as a result the energy scale associated with the formation of the
+condensate is scaling linearly with T_c. The a-b planes and the c axis also
+follow the same scaling relation. It is observed that the scaling behavior for
+the dirty limit and the Josephson effect (assuming a BCS formalism) are
+essentially identical, suggesting that in some regime these two effects may be
+viewed as equivalent. This raises the possibility that electronic
+inhomogeneities in the copper-oxygen planes may play an important role in the
+nature of the superconductivity in the copper-oxide materials.",0410719v2
+2006-04-23,"Comment on ""Performance of a spin based insulated gate field effect transistor"" [cond-mat/0603260] [cond-mat/0603260]","In a recent e-print [cond-mat/0603260] Hall and Flatte claim that a
+particular spin based field effect transistor (SPINFET), which they have
+analyzed, will have a lower threshold voltage, lower switching energy and lower
+leakage current than a comparable metal oxide semiconductor field effect
+transistor (MOSFET). Here, we show that all three claims of HF are invalid.",0604532v1
+2006-05-09,Self-Organized Networks and Lattice Effects in High Temperature Superconductors,"The entirely orbital self-organized dopant percolative filamentary model
+describes many counter-intuitive chemical trends in oxide superconductors
+quantitatively, especially the high superconductive transition temperatures Tc.
+According to rules previously used successfully for network glasees, the host
+networks are marginally stable mechanically, and the high Tc's are caused by
+network softening, which produces large electron-phonon interactions at
+interlayer dopants for states near the Fermi energy.",0605217v1
+2006-09-11,"Inhomogeneous superconductivity and the ""pseudogap state of novel superconductors","Novel superconducting compounds such as the high Tc oxides are intrinsically
+inhomogeneous systems. An inhomogeneous structure is created by doping and the
+statistical nature of the distribution of dopants. Consequently, the critical
+temperature is spatially dependent: Tc = Tc (r).",0609260v1
+2002-04-17,The Target Silicon Detector for the FOCUS Spectrometer,"We describe a silicon microstrip detector interleaved with segments of a
+beryllium oxide target which was used in the FOCUS photoproduction experiment
+at Fermilab. The detector was designed to improve the vertex resolution and to
+enhance the reconstruction efficiency of short-lived charm particles.",0204023v1
+1997-03-08,D=9 supergravity and p-brane solitons,"We construct the N=2, D=9 supergravity theory up to the quartic fermionic
+terms and derive the supersymmetry transformation rules for the fields modulo
+cubic fermions. We consider a class of p-brane solutions of this theory, the
+stainless p-branes, which cannot be isotropically oxidized into higher
+dimensions. The new stainless elementary membrane and elementary particle
+solutions are found. It is explicitly verified that these solutions preserve
+half of the supersymmetry.",9703063v1
+2004-05-18,"Oxidizing SuperYang-Mills from (N=4,d=4) to (N=1,d=10)","We introduce superspace generalizations of the transverse derivatives to
+rewrite the four-dimensional N=4 Yang-Mills theory into the fully
+ten-dimensional N=1 Yang-Mills in light-cone form. The explicit SuperPoincare
+algebra is constructed and invariance of the ten-dimensional action is proved.",0405150v2
+2007-06-06,Raman Spectroscopy of Nanostructures and Nanosized Materials,"The interest of micro and tip-enhanced Raman spectroscopy to analyze
+nanosized and nanostructured materials, chiefly semiconductors, oxides and
+pristine or functionalized carbon nanotubes, is reviewed at the light of the
+contributions to this special issue. Particular attention is paid to the fact
+that chemical reactions, size or shape distribution, defects, strain and
+couplings may add to nano-dimensionality in defining the Raman signature.",0706.0775v1
+2007-10-18,Surface Enhanced Raman Scattering Investigation of Uranium Hydride and Uranium Oxide,"The present approach to SERS does not rely on a hihj electrical conductivity
+substrate or admixture to enable the SERS process. The novelty of our method is
+to create an artificial periodic electron distribution on a surface by
+illumination with ultraviolet radiation whose photon energy is above the
+photoelectric work function of the material.",0710.3596v1
+2007-12-14,Carbon in the trigonal prismatic environment of rheniums complexes,"The electronic state of carbon in trigonal prismatic environment of rheniums
+was studied with electron localization function and was shown to be
+characterized by sp2 hybridisation and oxidation state minus 4.",0712.2278v1
+2008-05-28,Changes in the electronic structure and properties of graphene induced by molecular charge-transfer,"Interaction with electron donor and acceptor molecules such as aniline and
+nitrobenzene brings about marked changes in the Raman spectrum and the
+electronic structure of graphene, prepared by the exfoliation of graphitic
+oxide.",0805.4242v1
+2008-05-28,Nernst effect of epitaxial YBCO films doped with Ca and Zn,"We report Nernst effect measurements for some crystalline films of Ca and
+Zn-doped yttrium barium copper oxide grown by pulsed laser deposition. We argue
+that our results and most of the published data for LSCO are consistent with
+the theory of Gaussian superconducting fluctuations.",0805.4293v1
+2009-03-13,Mechanisms for higher $T_C$ in copper oxide superconductors; Ideas from band calculations,"Band calculations for the hole doped La$_2$CuO$_4$ system show that
+artificial periodicities of Ba dopants can give the material different
+properties than from a uniform distribution of dopants. A periodicity within
+the planes make static pseudogaps which could be tuned to raise the
+density-of-states (DOS) at $E_F$ and the superconducting $T_C$.
+  A periodic doping dependence perpendicular to the CuO planes can increase the
+matrix element for spin fluctuations.",0903.2335v1
+2009-03-22,An Experimental and Kinetic Modeling Study of the Oxidation of the Four Isomers of Butanol,"Butanol, and alcohol which can be produced from biomass sources",0903.3708v1
+2009-03-22,A Tentative Modeling Study of the Effect of Wall Reactions on Oxidation Phenomena,"This paper gives details of a tentative modeling study that investigates the
+inhibiting effect of internal reactor walls treated with acid...",0903.3750v1
+2009-10-01,Photonic Crystal Cavities in Silicon Dioxide,"One dimensional nano-beam photonic crystal cavities fabricated in silicon
+dioxide are considered in both simulation and experiment. Quality factors of
+over 10^4 are found via simulation, while quality factors of over 5*10^3 are
+found in experiment, for cavities with mode volumes of 2.0 cubic wavelengths
+(in oxide) and in the visible wavelength range (600-716nm). The dependences of
+the cavity quality factor and mode volume for different design parameters are
+also considered.",0910.0222v1
+2009-10-19,Effect of a polymer additive on heat transport in turbulent Rayleigh-Bénard convection,"Measurements of heat transport, as expressed by the Nusselt number $Nu$, are
+reported for turbulent Rayleigh-B\'enard convection of water containing up to
+120 ppm by weight of poly-[ethylene oxide] with a molecular weight of
+$4\times10^6$ g/mole. Over the Rayleigh number range $ 5\times 10^9 \alt Ra
+\alt 7 \times 10^{10}$ $Nu$ is smaller than it is for pure water by up to 10%.",0910.3678v1
+2009-10-28,Test of scaling theory in two dimensions in the presence of valley splitting and intervalley scattering in Si-MOSFETs,"We show that once the effects of valley splitting and intervalley scattering
+are incorporated, renormalization group theory consistently describes the
+metallic phase in silicon metal-oxide-semiconductor field-effect transistors
+down to the lowest accessible temperatures.",0910.5510v1
+2010-03-14,Laser-assisted coloration of Ti: oxides or nanostructures?,"Coloration of a Ti target under its ablation with picosecond laser pulses in
+liquids is ascribed to the formation of self-organized nanostructures. The
+density of nanostructures increases in an avalanche-like way with the number of
+laser pulses. The Raman peaks observed in the laser-exposed areas may be due to
+the auto-SERS effect.",1003.2796v1
+2010-06-22,Coordinated Analyses of Presolar Grains in the Allan Hills 77307 and Queen Elizabeth Range 99177 Meteorites,"We report the identification of presolar silicates (~177 ppm), presolar
+oxides (~11 ppm), and one presolar SiO2 grain in the Allan Hills (ALHA) 77307
+chondrite. Three grains having Si isotopic compositions similar to SiC X and Z
+grains were also identified, though the mineral phases are unconfirmed. Similar
+abundances of presolar silicates (~152 ppm) and oxides (~8 ppm) were also
+uncovered in the primitive CR chondrite Queen Elizabeth Range (QUE) 99177,
+along with 13 presolar SiC grains and one presolar silicon nitride. The O
+isotopic compositions of the presolar silicates and oxides indicate that most
+of the grains condensed in low-mass red giant and asymptotic giant branch
+stars. Interestingly, unlike presolar oxides, few presolar silicate grains have
+isotopic compositions pointing to low-metallicity, low-mass stars (Group 3).
+The 18O-rich (Group 4) silicates, along with the few Group 3 silicates that
+were identified, likely have origins in supernova outflows. This is supported
+by their O and Si isotopic compositions. Elemental compositions for 74 presolar
+silicate grains were determined by scanning Auger spectroscopy. Most of the
+grains have non-stoichiometric elemental compositions inconsistent with
+pyroxene or olivine, the phases commonly used to fit astronomical spectra, and
+have comparable Mg and Fe contents. Non-equilibrium condensation and/or
+secondary alteration could produce the high Fe contents. Transmission electron
+microscopic analysis of three silicate grains also reveals non-stoichiometric
+compositions, attributable to non-equilibrium or multistep condensation, and
+very fine scale elemental heterogeneity, possibly due to subsequent annealing.
+The mineralogies of presolar silicates identified in meteorites thus far seem
+to differ from those in interplanetary dust particles.",1006.4389v2
+2010-08-12,Anisotropy of DC Electric Field Influence on Acoustic Wave Propagation in Piezoelectric Plate,"Anisotropy of dc electric field influence on the different types of acoustic
+waves in piezoelectric plate has been investigated by means of computer
+simulation. Detail calculations have made for bismuth germanium oxide crystals.",1008.2058v1
+2010-10-07,Cathodoluminescence and Selective Emission of Er3+ in Oxides,"The dependence of the Er3+ cathodoluminescence and selective emission on the
+power of the YAG:Er3+ and Er2O3 excitation by an electron beam is
+spectroscopically studied for applications in high-intensity radiation sources
+of the visible and near-IR spectral ranges.",1010.1452v1
+2010-11-24,LaAlO3/SrTiO3-Based Device Concepts,"This is a book chapter that covers several device concepts based on the
+LaAlO3/SrTiO3 interface.",1011.5290v1
+2011-01-15,On the hardness of boron (III) oxide,"Our findings show that the hardness of glass-like B2O3 is of about 1.5 GPa,
+while the hardness of the high-pressure phase is higher by a factor of 10
+(16(5) GPa) and comparable with the hardness (16 GPa) of the WC-10% Co hard
+alloy.",1101.2965v1
+2011-10-19,"Growth of narrow-neck, epitaxial and nearly spherical Ge nanoislands on air-exposed Si(111)-(7$\times$7) surfaces","Growth of narrow-neck, epitaxial as well as non-epitaxial and nearly
+spherical Ge islands on air-exposed Si(111)-(7\times7) surfaces has been
+investigated by in-situ scanning tunnelling microscopy (STM) and ex-situ high
+resolution cross-sectional transmission electron microscopy (HRXTEM). A thin
+oxide is formed on Si(111)-(7\times7) surfaces via air exposure. Ge islands are
+grown on this oxide. STM measurements reveal the growth of very small (~2 nm
+diameter) Ge islands with a high number density of about 1.8\times10^12 cm-2.
+The island size has been found to depend on the amount of deposited Ge as well
+as the substrate temperature during Ge deposition. HRXTEM micrographs reveal
+that the islands are nearly spherical in shape, making narrow-neck contact with
+the substrate surface. At 520{\deg}C growth temperature both epitaxial and
+non-epitaxial islands grow. However, at 550{\deg}C, Ge islands predominantly
+grow epitaxially by a narrow-contact with Si via voids in the oxide layer.
+Growth of vertically elongated Ge islands is also observed in HRXTEM
+measurements with a very small diameter-to-height aspect ratio (~0.5-1), a
+hitherto unreported feature of epitaxial Ge growth on Si surfaces. In addition,
+stacking fault and faceting are observed in islands as small as 5 nm diameter.
+Ge islands, not even in contact with the Si substrate, appear to be in
+epitaxial alignment with the Si substrate. The island size distribution is
+essentially monomodal. As the contact area of Ge islands with Si through the
+voids in the oxide layer can be controlled via growth temperature, the results
+indicate that tunability of the potential barrier at the interface and
+consequently the tunability of electronic levels and optical properties can be
+achieved by the control of growth temperature.",1110.4242v1
+2012-03-03,Suppression of inelastic electron-electron scattering in Anderson Insulators,"We report on measurements of absorption from applied ac fields in
+Anderson-localized indium-oxide films. The absorption shows a roll-off at a
+frequency that is much smaller than the electron-electron scattering rate
+measured at the same temperature in diffusive samples of this material. These
+results are interpreted as evidence for discreteness of the energy spectrum.",1203.0673v2
+2012-03-30,Rethinking the Paleoproterozoic Great Oxidation Event: A Biological Perspective,"Competing geophysical/geochemical hypotheses for how Earth's surface became
+oxygenated - organic carbon burial, hydrogen escape to space, and changes in
+the redox state of volcanic gases - are examined and a more biologically-based
+hypothesis is offered in response. It is argued that organic carbon burial is
+of minor importance to the accumulation of oxygen in a mainly anoxic world
+where aerobic respiration is not globally significant. Thus, for the Great
+Oxidation Event (GOE) ~ 2.4 Gyr ago, an increasing flux of O2 due to its
+production by an expanding population of cyanobacteria is parameterized as the
+primary source of O2. Various factors would have constrained cyanobacterial
+proliferation and O2 production during most of the Archean and therefore a long
+delay between the appearance of cyanobacteria and oxygenation of the atmosphere
+is to be expected. Destruction of O2 via CH4 oxidation in the atmosphere was a
+major O2 sink during the Archean, and the GOE is explained to a significant
+extent by a large decline in the methanogen population and corresponding CH4
+flux which, in turn, was caused primarily by partial oxygenation of the surface
+ocean. The partially oxygenated state of these waters also made it possible for
+an aerobic methanotroph population to become established. This further
+contributed to the large reduction in the CH4 flux to the atmosphere by
+increasing the consumption of CH4 diffusing upwards from the deeper anoxic
+depths of the water column as well as any CH4 still being produced in the upper
+layer. The reduction in the CH4 flux lowered the CH4 oxidation sink for O2 at
+about the same time the metamorphic and volcanic gas sinks for O2 also
+declined. As the O2 source increased from an expanding population of
+cyanobacteria - triggered by a burst of continent formation ~ 2.7-2.4 Gyr ago -
+the atmosphere flipped and became permanently oxygenated.",1203.6701v1
+2012-06-15,Hubbard U and Hund's Exchange J in Transition Metal Oxides: Screening vs. Localization Trends from Constrained Random Phase Approximation,"In this work, we address the question of calculating the local effective
+Coulomb interaction matrix in materials with strong electronic Coulomb
+interactions from first principles. To this purpose, we implement the
+constrained random phase approximation (cRPA) into a density functional code
+within the linearized augmented plane wave (LAPW) framework.
+  We apply our approach to the 3d and 4d early transition metal oxides SrMO3
+(M=V, Cr, Mn) and (M=Nb, Mo, Tc) in their paramagnetic phases. For these
+systems, we explicitly assess the differences between two physically motivated
+low-energy Hamiltonians: The first is the three-orbital model comprising the
+t2g states only, that is often used for early transition metal oxides. The
+second choice is a model where both, metal d- and oxygen p-states are retained
+in the construction of Wannier functions, but the Hubbard interactions are
+applied to the d-states only (""d-dp Hamiltonian""). Interestingly, since -- for
+a given compound -- both U and J depend on the choice of the model, so do their
+trends within a family of these compounds. In the 3d perovskite series SrMO3
+the effective Coulomb interactions in the t2g Hamiltonian decrease along the
+series, due to the more efficient screening. The inverse -- generally expected
+-- trend, increasing interactions with increasing atomic number, is however
+recovered within the more localized ""d-dp Hamiltonian"". Similar conclusions are
+established in the layered 4d perovskites series Sr2MO4 (M=Mo, Tc, Ru, Rh).
+Compared to their isoelectronic and isostructural 3d analogues, the 4d 113
+perovskite oxides SrMO3 (M=Nb, Mo, Tc) exhibit weaker screening effects.
+Interestingly, this leads to an effectively larger U on 4d shells than on 3d
+when a t2g model is constructed.",1206.3533v2
+2012-09-20,Compositional disorder and tranport peculiarities in the amorphous indium-oxides,"(abridged) We present results of the disorder-induced
+metal-insulator-transition (MIT) in three-dimensional amorphous indium-oxide
+films. The amorphous version studied here differs from the one reported earlier
+[PRB 46, 10917 (1992)] in that it has a much lower carrier concentration. As a
+measure of the static disorder we use the dimensionless parameter kFl. Thermal
+annealing is employed as the experimental handle to tune the disorder. On the
+metallic side of the transition, the low temperature transport exhibits
+weak-localization and electron-electron correlation effects characteristic of
+disordered electronic systems. The MIT occurs at a kFl~0.3 for both versions of
+the amorphous material. However, in contrast with the results obtained on the
+electron-rich version of this system, no sign of superconductivity is seen down
+to ~0.3K even for the most metallic sample used in the current study. This
+demonstrates that using kFl as a disorder parameter for the
+superconductor-insulator-transition (SIT) is an ill defined procedure. A
+microstructural study of the films, employing high resolution chemical
+analysis, gives evidence for spatial fluctuations of the stoichiometry. This
+brings to light that, while the films are amorphous and show excellent
+uniformity in transport measurements of macroscopic samples, they contain
+compositional fluctuations that extend over mesoscopic scales. It is argued
+that this compositional disorder may be the reason for the apparent violation
+of the Ioffe-Regel criterion in the two versions of the amorphous indium-oxide.
+However, more dramatic effects due to this disorder are expected when
+superconductivity sets in, which are in fact consistent with the prominent
+transport anomalies observed in the electron-rich version of indium-oxide. The
+relevance of compositional disorder to other systems near their SIT is
+discussed.",1209.4417v1
+2012-11-30,Functional robust regression for longitudinal data,"We present a robust regression estimator for longitudinal data, which is
+especially suited for functional data that has been observed on sparse or
+irregular time grids. We show by simulation that the proposed estimators
+possess good outlier-resistance properties compared with the traditional
+functional least-squares estimator. As an example of application, we study the
+relationship between levels of oxides of nitrogen and ozone in the city of San
+Francisco.",1211.7332v1
+2013-02-06,Flexible transistors exploiting P3HT on paper substrates and graphene oxide films as gate dielectrics: proof of concept,"In this paper we report: the use of GO in aqueous solution as a gate
+dielectric material, its application to a MOS transistor based on organic
+semiconductor and the use of paper as substrate material.",1302.1291v1
+2013-11-21,Miscibility of blends of poly(methyl methacrylate) and oligodiols based on a bisphenol A nucleus and ethylene oxide or propylene oxide branches,"Cloud-point curves of blends of poly(methyl methacrylate) (PMMA) with a
+series of oligodiols based on a bisphenol A nucleus and short branches of
+poly(ethylene oxide) or poly(propylene oxide) (BPA-EO or BPA-PO), and with PEO
+and PPO oligomers, were obtained using a light transmission device.
+Experimental results were fitted with the Flory- Huggins model using an
+interaction parameter depending on both temperature and composition. For
+PMMA/PEO and PMMA/PPO blends, the miscibility increased when increasing the
+size of the diol, due to the significant decrease in the entropic and enthalpic
+terms contributing to the interaction parameter. This reflected the decrease in
+the selfassociation of solvent molecules and in the contribution of terminal OH
+groups to the mismatching of solubility parameters. For PMMA/BPA-EO blends, a
+decrease of the entropic contribution to the interaction parameter when
+increasing the size of the oligodiol was also found. However, the effect was
+counterbalanced by the opposite contribution of combinatorial terms leading to
+cloud-point curves located in approximately the same temperature range. For
+PMMA/BPA-PO blends, the interaction parameter exhibited a very low value. In
+this case, the effect of solvent size was much more important on combinatorial
+terms than on the interaction parameter, leading to an increase in miscibility
+when decreasing the oligodiol size. For short BPA-PO oligodiols no phase
+separation was observed. The entropic contribution of the interaction parameter
+exhibited an inverse relationship with the size of the oligodiols, independent
+of the nature of the chains bearing the hydroxyls and the type of OH groups
+(primary or secondary). This indicates that the degree of self-association of
+solvent molecules through their OH terminal groups, was mainly determined by
+their relative sizes.",1311.5452v1
+2014-09-23,Study Of Organic Monolayer Modified Metal Oxide Semiconductor Devices For High Temperature Applications,"We report fabrication and characteristics of an organic monolayer based Metal
+Oxide Semiconductor (MOS) device. In place of SiO2 oxide layer in the MOS
+configuration, we used 1H, 1H, 2H, 2H- perfluorooctyl trichlorosilane (FOTS)
+self-assembled monolayer as a substitution. The MOS device was fabricated by
+simple steps like sputter deposition and dip coating method. The device was
+heat treated to different temperatures to understand its performance and
+efficiency for high temperature application. The MOS device was heated to
+150{\deg} C, 350{\deg}C and 550{\deg}C and the energy band gap was found to be
+varied in the order 2.5 eV, 3.0 eV and 3.4eV respectively. For non-heated
+sample, the energy band gap is 3.4 eV. The results shows that the parameters
+like charge mobility ({\mu}), energy band gap, and resistance were found to be
+decreased after the heat treatment. The change in the energy band gap due to
+heat treatment has significantly influenced the I-V and the impedance
+characteristics. We observed that the MOS device started to conduct between 1V
+to 3V, further the device conduct till 20V. Impedance analysis show that device
+heated to 350 {\deg}C shows the low impedance but the impedance starts to
+increase for further heating up to 550{\deg}C. Using Multi Dielectric Energy
+Band Diagram Program (MEBDP) we studied the MOS structure and C-V
+characteristics and temperature dependent behavior of the devices from 100K to
+600K. Our experimental work and simulation studies confirm that the FOTS SAM
+substituted MOS device could be used for high temperature applications. The
+experimental observations are well supported by the simulation results. This
+study shows that the FOTS organic monolayer are promising substitute for SiO2
+oxide layer in the MOS and MOSFET which could be used high temperature
+applications.",1409.6401v1
+2014-12-15,"Defect physics, delithiation mechanism, and electronic and ionic conduction in layered lithium manganese oxide cathode materials","Layered LiMnO$_2$ and Li$_2$MnO$_3$ are of great interest for lithium-ion
+battery cathodes because of their high theoretical capacities. The practical
+application of these materials is, however, limited due to poor electrochemical
+performance. We herein report a comprehensive first-principles study of defect
+physics in LiMnO$_2$ and Li$_2$MnO$_3$ using hybrid-density functional
+calculations. We find that manganese antisites have low formation energies in
+LiMnO$_2$ and may act as nucleation sites for the formation of impurity phases.
+The antisites can also occur with high concentrations in Li$_2$MnO$_3$;
+however, unlike in LiMnO$_2$, they can be eliminated by tuning the experimental
+conditions during preparation. Other intrinsic point defects may also occur and
+have an impact on the materials' properties and functioning. An analysis of the
+formation of lithium vacancies indicates that lithium extraction from LiMnO$_2$
+is associated with oxidation at the manganese site, resulting in the formation
+of manganese small hole polarons; whereas in Li$_2$MnO$_3$ the intrinsic
+delithiation mechanism involves oxidation at the oxygen site, leading to the
+formation of bound oxygen hole polarons $\eta_{\rm O}^{+}$. The layered oxides
+are found to have no or negligible bandlike carriers and they cannot be doped
+n- or p-type. The electronic conduction proceeds through hopping of hole and/or
+electron polarons; the ionic conduction occurs through lithium monovacancy
+and/or divacancy migration mechanisms. Since $\eta_{\rm O}^{+}$ is not stable
+in the absence of negatively charged lithium vacancies in bulk Li$_2$MnO$_3$,
+the electronic conduction near the start of delithiation is likely to be poor.
+We suggest that the electronic conduction associated with $\eta_{\rm O}^{+}$
+and, hence, the electrochemical performance of Li$_2$MnO$_3$ can be improved
+through nanostructuring and/or ion substitution.",1412.4688v2
+2015-05-30,Superconducting interaction charge in thallium-based high-Tc cuprates: Roles of cation oxidation state and electronegativity,"Superconductivity in the Tl-based cuprates encompasses a notably broad range
+of measured optimal transition temperatures Tc0, ranging from lowest in the
+charge-depleted Tl-1201 compounds
+(Tl$_{1-x}$(Ba/Sr)$_{1+y}$La$_{1-y}$CuO$_{5-{\delta}}$), such as
+Tl$_{0.7}$LaSrCuO$_5$ (37 K) and TlBa$_{1.2}$La$_{0.8}$CuO$_5$ (45.4 K), to
+highest in the Tl-1223 compound TlBa$_2$Ca$_2$Cu$_3$O$_{9{\pm}{\delta}}$ (133.5
+K). Seven Tl-based cuprates are considered and compared using the model of
+superconductive pairing via electronic interactions between two physically
+separated charge reservoirs, where Tc0 $\propto$
+({\sigma}{\eta}/A)$^{1/2}${\zeta}$^{-1}$ is determined by the superconducting
+interaction charge fraction {\sigma} the number {\eta} of CuO$_2$ layers, and
+the basal-plane area A, each per formula unit, and the transverse distance
+{\zeta} between interacting layers. Herein it is demonstrated that {\sigma}
+follows from the elemental electronegativity and the oxidation state of Tl, and
+other structurally analogous cations. The comparatively lower elemental
+electronegativity of Tl, in conjunction with its oxidation state, explains the
+higher {\sigma} and Tc0 values in the Tl-based compounds relative to their
+Bi-based cuprate homologues. A derivation of {\sigma} is introduced for the
+optimal Tl$_2$Ba$_2$Ca$_{{\eta}-1}$Cu$_{\eta}$O$_{2{\eta}+4}$ (for {\eta} = 1,
+2, 3) compounds, which exhibit a Tl oxidation state at or near +3, obtaining
+the fundamental value {\sigma}$_0$ = 0.228 previously established for
+YBa$_2$Cu$_3$O$_{6.92}$. Also reported is the marked enhancement in {\sigma}
+associated with Tl$^{+1}$ and analogous inner-layer cations relative to
+higher-valence cations. For a model proposition of {\sigma} = {\sigma}$_0$, the
+fractional Tl$^{+1}$ content of the mixed-valence compound,
+TlBa$_2$Ca$_2$Cu$_3$O$_{9{\pm}{\delta}}$, is predicted to be 1/3 at
+optimization, in agreement ...",1506.00065v1
+2015-10-17,In-operando synchronous time-multiplexed O K-edge x-ray absorption spectromicroscopy of functioning tantalum oxide memristors,"Memristors are receiving keen interest because of their potential varied
+applications and promising large-scale information storage capabilities.
+Tantalum oxide is a memristive material that has shown promise for
+high-performance nonvolatile computer memory. The microphysics has been elusive
+because of the small scale and subtle physical changes that accompany
+conductance switching. In this study, we probed the atomic composition, local
+chemistry and electronic structure of functioning tantalum oxide memristors
+through spatially mapped O K-edge x-ray absorption. We developed a
+time-multiplexed spectromicroscopy technique to enhance the weak and possibly
+localized oxide modifications with spatial and spectral resolutions of <30 nm
+and 70 meV, respectively. During the initial stages of conductance switching of
+a micrometer sized crosspoint device, the spectral changes were uniform within
+the spatial resolution of our technique. When the device was further driven
+with millions of high voltage-pulse cycles, we observed lateral motion and
+separation of ~100 nm-scale agglomerates of both oxygen interstitials and
+vacancies. We also demonstrate a unique capability of this technique by
+identifying the relaxation behavior in the material during electrical stimuli
+by identifying electric field driven changes with varying pulse widths. In
+addition, we show that changes to the material can be localized to a spatial
+region by modifying its topography or uniformity, as against spatially uniform
+changes observed here during memristive switching. The goal of this report is
+to introduce the capability of time-multiplexed x-ray spectromicroscopy in
+studying weak-signal transitions in inhomogeneous media through the example of
+the operation and temporal evolution of a memristor.",1510.05066v1
+2015-11-30,Plasmonic Induced Potential in Metal-Semiconductor Composits,"We utilize experimental tools such as conductive atomic force microscopy and
+electrostatic force microscopy on photo-excited arrays of gold nanoparticles on
+indium tin oxide substrate. The nanoparticles are partially covered by a thin
+semiconductor polymer. The change in the current and potential profiles of the
+composite metal-semiconductor sample after excitation at plasmonic resonance
+frequency of metallic nanoparticles is analyzed.",1511.09162v1
+2016-03-19,"Quantitative use of electron energy-loss spectroscopy Mo-M$_{2,3}$ edges for the study of molybdenum oxides","Because of the large energy separation between O-K and Mo-L$_{2,3}$ edges,
+extracting precise and reliable chemical information from core-loss EELS
+analyze of molybdenum oxides has always been a challenge. In this regard
+Mo-M$_{2,3}$ edges represents an interesting alternative as they are situated
+close to the O-K edges. They should allow thus the extraction of a wealth of
+chemical information from the same spectra. However the main difficulty to
+overcome in order to work properly with these edges is the delayed maxima of
+the Mo-M$_{4,5}$ edges which hinders the automated background subtraction with
+the usual inverse power low function. In this study we propose another
+background subtraction method specifically designed to overcome this obstacle
+and we apply it to the study of MoO3 and MoO2. We are able to show that
+quantitative chemical information can be precisely and accurately determined
+from the joined analyze of O-K and Mo-M$_{2,3}$ edges. In particular k-factors
+are derived as a function of the integration window width and standard errors
+close to 2% are reported. The possibility to discriminate the two oxides thanks
+to chemical shifts and energy-loss near-edge structures is also investigated
+and discussed. Furthermore the M$_3$/M$_2$ ratios are derived and are found to
+be strongly dependent on the local chemical environment. This result is
+confirmed by multiplet calculations for which the crystal field parameters have
+been determined by ab initio calculations. The whole methodology as well as the
+conclusions presented in this paper should be easily transposable to any
+transitions metal oxides of the 4d family. This work should open a new and
+easier way regarding the quantitative EELS analyses of these compounds.",1603.06070v1
+2016-06-09,Can the structure of amorphous indium gallium zinc oxide be described in terms of a few polyhedral motifs?,"The coordination polyhedra around the cations are the building blocks of
+ionic solids. In context of amorphous InGaZn oxide (a-IGZO), even though the
+coordination polyhedra are irregularly arranged, it will be beneficial to
+identify them. In this work, we address the questions, (a) is it possible to
+classify all the polyhedra that occur in a-IGZO into only a few distinct
+groups? and (b) are these the same polyhedral motifs as those observed in the
+crystalline indium gallium zinc oxide (c-IGZO) or other related crystalline
+oxides of indium, gallium and zinc? Therefore, in this first principles based
+study, a large number (ten) of equivalent samples of a-IGZO were prepared by ab
+initio melt-and-quench molecular dynamics, so that several distinct samples of
+the amorphous landscape are obtained. The combination of all these structures
+thus obtained is a better representation of a real a-IGZO sample. For the ten
+samples containing 360 cations, we propose a simpler and more accurate method
+for determining the coordination number of each polyhedron, which was verified
+by charge density plots. Based on a method of comparing bond angles between
+metal and oxygen atoms, the identified polyhedra were matched to the polyhedral
+motifs present in the related crystalline systems, such as, InGaZnO4, In2O3,
+Ga2O3 and ZnO. We find, the a-IGZO primarily consists of the following
+polyhedra: a tetrahedron from space group 199 and an octahedron from space
+group 206 of In2O3; a tetrahedron from space group 12 and an octahedron from
+space group 167 of Ga2O3; a tetrahedron from space group 186 of ZnO; zinc and
+gallium trigonal bipyramids from c-IGZO; and one zinc 4-fold, one zinc 5-fold
+and one indium 5-fold coordination polyhedra that occur only in the amorphous
+phase. We are able to reduce the description of structure from 360 to 10 groups
+of polyhedra. The benefits of this identification could be enormous.",1606.02842v1
+2016-06-27,Structural and electronic phase evolution of Tin dioxide,"We investigate the effect of controlled annealing on the structural and
+electronic phase evolution of Tin dioxide from Tin (II) oxyhydroxide prepared
+by simple precipitation method. Thermogravimetric analysis suggests a complex
+weight loss-gain process involved, passing through an intermediate phase of tin
+oxide nanoparticles. The probable structural and electronic phase evolution is
+discussed using detailed X-ray diffraction and X-ray photoelectron spectroscopy
+investigations.",1606.08137v1
+2018-11-14,Complex symplectic structures on Lie algebras,"We investigate Lie algebras endowed with a complex symplectic structure and
+develop a method, called \emph{complex symplectic oxidation}, to construct
+certain complex symplectic Lie algebras of dimension $4n+4$ from those of
+dimension $4n$. We specialize this construction to the nilpotent case and apply
+complex symplectic oxidation to classify eight-dimensional nilpotent complex
+symplectic Lie algebras.",1811.05969v1
+2020-07-10,Quantum interference effects of out-of-plane confinement on two-dimensional electron systems in oxides,"It was recently discovered that a conductive, metallic state is formed on the
+surface of some insulating oxides. Firstly observed on SrTiO$_3$(001), it was
+then found in other compounds as diverse as anatase TiO$_2$, KTaO$_3$,
+BaTiO$_3$, ZnO, and also on different surfaces of SrTiO$_3$ (or other oxides)
+with different symmetries. The spatial extension of the wave function of this
+electronic state is of only a few atomic layers. Experiments indicate its
+existence is related to the presence of oxygen vacancies induced at or near the
+surface of the oxide. In this article we present a simplified model aimed at
+describing the effect of its small spatial extension on measurements of its 3D
+electronic structure by angular resolved photoemission spectroscopy (ARPES).
+For the sake of clarity, we base our discussion on a simple tight binding
+scheme plus a confining potential that is assumed to be induced by the oxygen
+vacancies. Our model parameters are, nevertheless, obtained from density
+functional calculations. With this methodology we can explain from a very
+simple concept of selective interference the ""wobbling"", i.e., the
+photoemission intensity modulation and/or apparent dispersion of the Fermi
+surface and spectra along the out-of-plane ($k_z$) direction, and the ""mixed
+2D/3D"" characteristics observed in some experiments. We conclude that the
+critical model parameters for such an effect are the relative strength of the
+electronic hopping of each band and the height/width aspect ratio of the
+surface confining potential. By considering recent photoemission measurements
+under the light of our findings, we can get relevant information on the
+electronic wave functions and of the nature of the confining potential.",2007.05605v1
+2010-05-13,Photostimulated spin-flip and the photodynamic therapeutic effect of fullerene solutions,"A new mechanism of photodynamic therapeutic effect of fullerene solution is
+suggested. Spin flip of electrons in oxygen molecule in the vicinity of
+negative-positive ion pair of fullerene lays the foundation of high oxidative
+activity of complexes C60(minus) -O2 and C60(plus)-O2.",1005.2383v1
+2014-03-10,Order quantification of hexagonal periodic arrays fabricated by in situ solvent-assisted nanoimprint lithography of block copolymers,"Directed self-assembly of block copolymer polystyrene-b-polyethylene oxide
+(PS-b-PEO) thin film was achieved by one-pot methodology of solvent vapour
+assisted nanoimprint lithography (SAIL).",1403.2250v1
+2016-11-28,Numerical Study of Pseudo-gap Anisotropy for a Tight Binding Band,"The Fermi surface anisotropy of a pseudo-gap in the spectral weight, caused
+by superconducting fluctuations or anti-ferromagnetic fluctuations, is
+calculated for a tight binding band. The importance of the Fermi surface saddle
+point, or hot spot, is illustrated. A peak-dip-hump structure due to a finite
+frequency mode, is briefly explored. The connection to high temperature
+superconducting copper-oxides is discussed.",1611.09305v1
+2018-05-09,Low-Noble-Metal-Loading Hybrid Catalytic System for Oxygen Reduction Utilizing Reduced-Graphene-Oxide-Supported-Platinum Aligned with Carbon-Nanotube-Supported Iridium,"Hybrid systems composed of the reduced graphene oxide-supported platinum and
+multiwall carbon nanotubes-supported iridium (both noble metals utilized at low
+loadings on the level of 15 and < 5 microg cm-2, respectively) have been
+considered as catalytic materials for the reduction of oxygen in acid media
+(0.5 mol dm-3 H2SO4). The electrocatalytic activity toward reduction of oxygen
+and formation of hydrogen peroxide intermediate have been tested using rotating
+ring-disk electrode voltammetric experiments. The efficiency of the proposed
+catalytic systems has also been addressed by performing galvanodynamic
+measurements with gas diffusion electrode half-cell at 80 {\deg}C. The role of
+carbon nanotubes is to improve charge distribution at the electrocatalytic
+interface and facilitate the transport of oxygen and electrolyte in the
+catalytic systems by lowering the extent of reduced graphene oxide restacking
+during solvent evaporation. The diagnostic electrochemical experiments reveal
+that at iridium-containing systems not only higher disk currents, but also much
+smaller ring currents have been produced (compared to reduced graphene
+oxide-supported platinum and its composite with bare carbon nanotubes), clearly
+implying formation of lower amounts of the undesirable hydrogen peroxide
+intermediate. The enhancement effect coming from the addition of traces of
+iridium (supported onto carbon nanotubes) to Pt, utilized at low loading, may
+originate from the high ability of Ir to induce decomposition of the
+undesirable hydrogen peroxide intermediate. There is a competition between
+activation (due to the presence of small amounts of Ir) and dilution (by carbon
+nanotubes) of Pt active centers in hybrid systems, therefore special attention
+is paid to the adjustment of their composition.",1805.03390v1
+2016-12-17,Electrons and polarons at oxide interfaces explored by soft-X-ray ARPES,"Soft-X-ray ARPES (SX-ARPES) with its enhanced probing depth and chemical
+specificity allows access to fundamental electronic structure characteristics -
+momentum-resolved spectral function, band structure, Fermi surface - of systems
+difficult and even impossible for the conventional ARPES such as
+three-dimensional materials, buried interfaces and impurities. After a recap of
+the spectroscopic abilities of SX-ARPES, we review its applications to oxide
+interfaces, focusing on the paradigm LaAlO3-SrTiO3 interface. Resonant SX-ARPES
+at the Ti L-edge accentuates photoemission response of the mobile interface
+electrons and exposes their dxy-, dyz- and dxz-derived subbands forming the
+Fermi surface in the interface quantum well. After a recap of the
+electron-phonon interaction physics, we demonstrate that peak-dip-hump
+structure of the experimental spectral function manifests the Holstein-type
+large polaron nature of the interface charge carriers, explaining their
+fundamentally reduced mobility. Coupling of the charge carriers to polar soft
+phonon modes defines dramatic drop of mobility with temperature. Oxygen
+deficiency adds another dimension to the rich physics of LaAlO3-SrTiO3
+resulting from co-existence of mobile and localized electrons introduced by
+oxygen vacancies. Oxygen deficiency allows tuning of the polaronic coupling and
+thus mobility of the charge carriers, as well as of interfacial ferromagnetism
+connected with various atomic configurations of the vacancies. Finally, we
+discuss spectroscopic evidence of phase separation at the LaAlO3-SrTiO3
+interface. Concluding, we put prospects of SX-ARPES for complex
+heterostructures, spin-resolving experiments opening the totally unexplored
+field of interfacial spin structure, and in-operando field-effect experiments
+paving the way towards device applications of the reach physics of oxide
+interfaces.",1612.05791v2
+2017-10-16,Is stripe incommensurability in La_{2-x}Sr_xCoO_4 proportional to doping?,"The longstanding notion of stripe incommensurability being proportional to
+doping, \delta(x) ~ x, in lanthanum transition-metal oxides, La_{2-x}Sr_xTmO_4
+(Tm = Cu, Ni, Co), is partly borne out by experiment but also plagued with
+exceptions. Future neutron-scattering experiments on cobaltates could provide a
+clear distinction whether a linear or square-root dependence, \delta(x) ~
+sqrt(x - x_0), is valid.",1710.06773v1
+2018-01-28,Constraints on metal oxide and metal hydroxide abundances in the winds of AGB stars - Potential detection of FeO in R Dor,"Using ALMA, we observed the stellar wind of two oxygen-rich Asymptotic Giant
+Branch (AGB) stars, IK Tau and R Dor, between 335 and 362 GHz. One aim was to
+detect metal oxides and metal hydroxides (AlO, AlOH, FeO, MgO, MgOH), some of
+which are thought to be direct precursors of dust nucleation and growth. We
+report on the potential first detection of FeO (v=0, Omega=4, J=11-10) in RDor
+(mass-loss rate, Mdot, ~1e-7 Msun/yr). The presence of FeO in IK Tau (Mdot~5e-6
+Msun/yr) cannot be confirmed due to a blend with 29SiS, a molecule that is
+absent in R Dor. The detection of AlO in R Dor and of AlOH in IK Tau was
+reported earlier by Decin et al. (2017). All other metal oxides and hydroxides,
+as well as MgS, remain undetected. We derive a column density N(FeO) of
+1.1+/-0.9e15 cm^{-2} in R Dor, or a fractional abundance [FeO/H]~1.5e-8
+accounting for non-LTE effects. The derived fractional abundance [FeO/H] is a
+factor ~20 larger than conventional gas-phase chemical kinetic predictions.
+This discrepancy may be partly accounted for by the role of vibrationally
+excited OH in oxidizing Fe, or may be evidence for other currently unrecognised
+chemical pathways producing FeO. Assuming a constant fractional abundance
+w.r.t. H_2, the upper limits for the other metals are [MgO/H_2] <5.5e-10 (R
+Dor) and <7e-11 (IK Tau), [MgOH/H_2] <9e-9 (R Dor) and <1e-9 (IK Tau),
+[CaO/H_2] <2.5e-9 (R Dor) and <1e-10 (IK Tau), [CaOH/H_2] <6.5e-9 (R Dor) and
+<9e-10 (IK Tau), and [MgS/H_$] <4.5e-10 (R Dor) and <6e-11 (IK Tau). The
+retrieved upper limit abundances for these latter molecules are in accord with
+the chemical model predictions.",1801.09302v1
+2018-01-29,Band alignments of electronic energy structure in epitaxially grown \b{eta}-Ga2O3 layers,"Gallium oxide epitaxial layers grown on native substrates and basal plane
+sapphire were characherized by X-ray phtotelectron and optical reflectance
+spectroscopies. The XPS electronic structure mapping was coupled to Density
+functional theory calculations.",1801.09451v1
+2018-09-17,Indium Tin Oxide/Barium Strontium Titanate THz Sensor Antenna,"A Bow-Tie ITO/BST and Au/BST antennas were designed and analyzed using the
+finite element, Multiphysics COMSOL program. The study shows that the outputs
+peak at several modes and ITO antennas allow for the integration of the antenna
+with optoelectronic devices.",1809.06449v1
+2019-06-10,Cation Disorder and Lithium Insertion Mechanism of Wadsley--Roth Crystallographic Shear Phases,"Wadsley--Roth crystallographic shear phases form a family of compounds that
+have attracted attention due to their excellent performance as lithium-ion
+battery electrodes. The complex crystallographic structure of these materials
+poses a challenge for first-principles computational modelling and hinders the
+understanding of their structural, electronic and dynamic properties. In this
+article, we study three different niobium-tungsten oxide crystallographic shear
+phases (Nb$_{12}$WO$_{33}$, Nb$_{14}$W$_{3}$O$_{44}$, Nb$_{16}$W$_5$O$_{55}$)
+using an enumeration-based approach and first-principles density-functional
+theory calculations. We report common principles governing the cation disorder,
+lithium insertion mechanism, and electronic structure of these materials.
+Tungsten preferentially occupies tetrahedral and block-central sites within the
+block-type crystal structures. The lithium insertion proceeds via a three-step
+mechanism, associated with an anisotropic evolution of the host lattice. Our
+calculations reveal an important connection between long-range and local
+structural changes: in the second step of the mechanism, the removal of local
+structural distortions leads to the contraction of the lattice along specific
+crystallographic directions, buffering the volume expansion of the material.
+Niobium-tungsten oxide shear structures host small amounts of localised
+electrons during initial lithium insertion due to the confining effect of the
+blocks, but quickly become metallic upon further lithiation. We argue that the
+combination of local, long-range, and electronic structural evolution over the
+course of lithiation is beneficial to the performance of these materials as
+battery electrodes. The mechanistic principles we establish arise from the
+compound-independent crystallographic shear structure, and are therefore likely
+to apply to Ti/Nb oxide or pure Nb oxide shear phases.",1906.04192v3
+2019-07-10,Environmental Stability of Bismuthene: Oxidation Mechanism and Structural Stability of 2D Pnictogens,"Recently a new group of two dimensional (2D) materials, originating from the
+group V elements (pnictogens), has gained global attention owing to their
+outstanding properties.",1907.04806v1
+2020-12-16,Interfacial electrical and chemical properties of deposited SiO2 layers in lateral implanted 4H-SiC MOSFETs subjected to different nitridations,"In this paper, SiO2 layers deposited on 4H-SiC and subjected to different
+post deposition annealing (PDA) in NO and N2O were studied to identify the key
+factors influencing the channel mobility and threshold voltage stability in
+4H-SiC MOSFETs. In particular, PDA in NO gave a higher channel mobility (55
+cm2V-1s-1) than PDA in N2O (20 cm2V-1s-1), and the subthreshold behavior of the
+devices confirmed a lower total amount of interface states for the NO case.
+This latter could be also deduced from the behavior of the capacitance-voltage
+characteristics of 4H-SiC MOSFETs measured in gate controlled diode
+configuration. On the other hand, cyclic gate bias stress measurements allowed
+to separate the contributions of interface states (Nit) both on the upper and
+bottom parts of the 4H-SiC band gap and near interface oxide traps (NIOTs) in
+the two oxides. In particular, it was found that NO annealing reduced the total
+density of charges trapped at the interface states down to 3 x 1011 cm- 2 and
+those trapped inside the oxide down to 1 x 1011 cm-2. Electron energy loss
+spectroscopy demonstrated that the reduction of these traps in the NO annealed
+sample is due to the lower amounts of sub-stoichiometric silicon oxide (~ 1nm)
+and carbon-related defects (< 1nm) at the interface, respectively. This
+correlation represents a further step in the comprehension of the physics of
+the SiO2/4H-SiC interface explaining the mobility and threshold voltage
+behavior of 4H-SiC MOSFETs.",2012.08829v3
+2017-05-12,Accumulation-layer Surface Plasmons,"A rigorous analytical study of the eigenmodes supported by a charge
+accumulation layer within a transparent conductive oxide (TCO) is presented.
+The new class of surface plasmons termed Accumulation-Layer Surface Plasmon
+(ASP) is introduced. Near resonance ASP are tightly bound and display a vast
+effective index tunability that could be of great practical interest. The
+suppression of ASP in the presence of epsilon-near zero regions is discussed.",1705.04552v1
+2017-09-13,Detection of titanium oxide in the atmosphere of a hot Jupiter,"As an exoplanet transits its host star, some of the light from the star is
+absorbed by the atoms and molecules in the planet's atmosphere, causing the
+planet to seem bigger; plotting the planet's observed size as a function of the
+wavelength of the light produces a transmission spectrum. Measuring the tiny
+variations in the transmission spectrum, together with atmospheric modelling,
+then gives clues to the properties of the exoplanet's atmosphere. Chemical
+species composed of light elements$-$such as hydrogen, oxygen, carbon, sodium
+and potassium$-$have in this way been detected in the atmospheres of several
+hot giant exoplanets, but molecules composed of heavier elements have thus far
+proved elusive. Nonetheless, it has been predicted that metal oxides such as
+titanium oxide (TiO) and vanadium oxide occur in the observable regions of the
+very hottest exoplanetary atmospheres, causing thermal inversions on the
+dayside. Here we report the detection of TiO in the atmosphere of the
+hot-Jupiter planet WASP-19b. Our combined spectrum, with its wide spectral
+coverage, reveals the presence of TiO (to a confidence level of 7.7{\sigma}), a
+strongly scattering haze (7.4{\sigma}) and sodium (3.4{\sigma}), and confirms
+the presence of water (7.9{\sigma}) in the atmosphere.",1709.04118v1
+2018-06-18,Effect of Dissolved Oxygen Content on Photocatalytic Performance of Graphene Oxide,"Graphene, a two-dimensional (2D) promising emergent photocatalyst consisting
+of earth-abundant elements. This study evaluated the potential of graphene
+oxide (GO) towards photocatalytic degradation of a novel organic dye, Methylene
+Blue (MB). In this work, photocatalytic activity of graphene oxide (GO),
+graphene oxide (GO) along with hydrogen peroxide (H2O2) were tested by
+photodegrading Methylene Blue (MB) in aqueous solution. The resulted GO
+nanoparticles were characterized by X-ray powder diffraction, Scanning Electron
+Microscopy, Energy Dispersive Spectroscopy and Fourier Transform Infrared Ray
+Spectroscopy. The XRD data confirms the sharp peak centered at 2Theta=10.44
+degree corresponding to (002) reflection of GO. Based on our results, it was
+found that the resulted GO nanoparticles along with H2O2 achieved ~92%
+photodecolorization of MB compared to ~63% for H2O2 under natural sunlight
+irradiation at pH~7 in 60 min. The influences of oxygen and hydrogen peroxide
+(H2O2) on the degradation of MB during sunlight/GO process were investigated.
+Experimental results indicated that oxygen was a determining parameter for
+promoting the photocatalytic degradation. The rate constant of degradation (k1)
+increased from 0.019 to 0.042 per minute for dissolved oxygen content (DOC) 3.5
+mg/L when direct photocatalysis (MB/GO) and H2O2-assisted photocatalysis
+(MB/H2O2/GO) were used. Owing to the fact that H2O2 acted as an electron and
+hydroxyl radicals scavenger, the addition of H2O2 should in a proper dosage to
+enhance the degradation of MB. Moreover, as the initial concentration of
+dissolved oxygen (DO) was increased from 2.8 to 3.9 mg/L, the rate constant of
+degradation (k1) increased from 0.035 to 0.062 per minute. The mechanism of
+photodegradation and kinetics were also studied for both direct photocatalysis
+and H2O2-assisted photocatalysis.",1806.06492v2
+2018-12-16,Performance-Enhanced Non-Enzymatic Glucose Sensor Based on Graphene-Heterostructure,"This study proposes a novel design of glucose sensor with enhanced
+selectivity and sensitivity by using graphene Schottky diodes, which is
+composed of Graphene (G)/Platinum Oxide (PtO)/n-Silicon (Si) heterostructure.
+The sensor was tested with different glucose concentrations and interfering
+solutions to investigate its sensitivity and selectivity. Different structures
+of the device were studied by adjusting the platinum oxide film thickness to
+investigate its catalytic activity. It was found that the film thickness plays
+a significant role in the efficiency of glucose oxidation and hence in overall
+device sensitivity. 0.8-2 uA output current was obtained in the case of 4-10 mM
+with a sensitivity of 0.2 uA/mM.cm2. Besides, results have shown that 0.8 uA
+and 15 uA were obtained by testing 4 mM glucose on two different PtO
+thicknesses, 30 nm, and 50 nm, respectively. The sensitivity of the device was
+enhanced by 150% (i.e., up to 30 uA/mM.cm2) by increasing the PtO layer
+thickness. This was attributed to both the increase of the number of active
+sites for glucose oxidation as well as the increase in the graphene layer
+thickness, which leads to enhanced charge carriers concentration and mobility.
+Moreover, theoretical investigations were conducted using the Density Function
+Theory (DFT) to understand the detection method and the origins of selectivity
+better. The working principle of the sensors puts it in a competitive position
+with other non-enzymatic glucose sensors. DFT calculations provided a
+qualitative explanation of the charge distribution across the graphene sheet
+within a system of a platinum substrate with D-glucose molecules above. The
+proposed G/PtO/n-Si heterostructure has proven to satisfy these factors, which
+opens the door for further developments of more reliable non-enzymatic
+glucometers for continuous glucose monitoring systems.",1812.06466v4
+2018-12-19,Compact grating coupler using asymmetric waveguide scatterers,"We demonstrate a novel grating coupler design based on double asymmetric and
+vertically oriented waveguide scatterers to efficiently couple normally
+incident light to a fundamental mode silicon waveguide laying on a buried oxide
+layer.",1812.07757v2
+2019-04-18,GHz Dielectric Measurement of Powdery TiO,"This study experimentally determines the dielectric properties of a powdery
+titanium (II) oxide (TiO) material within the microwave range (0.1-13.5 GHz).
+The properties were determined using a coaxial airline method using a
+TiO/paraffin mixture at several loading fractions. A permittivity of 60 for
+volume fraction below 30% and 100 for volume fraction above were measured.",1904.08765v1
+2019-11-01,Advanced chemical state studies of oxide films by lab-based HAXPES combining soft and hard X-ray sources,"The greater information depth provided in Hard X-ray Photoelectron
+Spectroscopy (HAXPES) enables non-destructive analyses of the chemistry and
+electronic structure of buried interfaces. Moreover, for industrially relevant
+elements like Al, Si and Ti, the combined access to the Al 1s, Si 1s or Ti 1s
+photoelectron line and its associated Al KLL, Si KLL or Ti KLL Auger
+transition, as required for local chemical state analysis on the basis of the
+Auger parameter, is only possible with hard X-rays. Until now, such
+photoemission studies were only possible at synchrotron facilities. Recently
+however, the first commercial XPS/HAXPES systems, equipped with both soft and
+hard X-ray sources, have entered the market, providing unique opportunities for
+monitoring the local chemical state of all constituent ions in functional
+oxides at different probing depths, in a routine laboratory environment.
+Bulk-sensitive shallow core-levels can be excited using either the hard or soft
+X-ray source, whereas more surface-sensitive deep core-level photoelectron
+lines and associated Auger transitions can be measured using the hard X-ray
+source. As demonstrated for thin Al2O3, SiO2 and TiO2 films, the local chemical
+state of the constituting ions in the oxide may even be probed at near constant
+probing depth by careful selection of sets of photoelectron and Auger lines, as
+excited with the combined soft and hard X-ray sources. We highlight the
+potential of lab-based HAXPES for the research on functional oxides and also
+discuss relevant technical details regarding the calibration of the kinetic
+binding energy scale.",1911.00428v1
+2019-11-04,Threshold Voltage variation with respect to Gate geometry in Nano-scale MOSFETS,"The tremendous progress in Metal Oxide Semiconductor (MOS) technology has
+been a direct consequence of device scaling for past several decades. But as we
+have entered the nanometer era many problems related to leakage currents and
+other issues related to variability impacting the yield are of concern. Herein
+we have investigated how the change in the Fin Architecture and Gate Length of
+the MOS device impacts the Threshold Voltage.",1911.03557v1
+2019-12-25,Deep Learning Aided Rational Design of Oxide Glasses,"Despite the extensive usage of oxide glasses for a few millennia, the
+composition-property relationships in these materials still remain poorly
+understood. While empirical and physics-based models have been used to predict
+properties, these remain limited to a few select compositions or a series of
+glasses. Designing new glasses requires a priori knowledge of how the
+composition of a glass dictates its properties such as stiffness, density, or
+processability. Thus, accelerated design of glasses for targeted applications
+remain impeded due to the lack of universal composition-property models.
+Herein, using deep learning, we present a methodology for the rational design
+of oxide glasses. Exploiting a large dataset of glasses comprising of up to 37
+oxide components and more than 100,000 glass compositions, we develop
+high-fidelity deep neural networks for the prediction of eight properties that
+enable the design of glasses, namely, density, Young's modulus, shear modulus,
+hardness, glass transition temperature, thermal expansion coefficient, liquidus
+temperature, and refractive index. These models are by far the most extensive
+models developed as they cover the entire range of human-made glass
+compositions. We demonstrate that the models developed here exhibit excellent
+predictability, ensuring close agreement with experimental observations. Using
+these models, we develop a series of new design charts, termed as glass
+selection charts. These charts enable the rational design of functional glasses
+for targeted applications by identifying unique compositions that satisfy two
+or more constraints, on both compositions and properties, simultaneously. The
+generic design approach presented herein could catalyze machine-learning
+assisted materials design and discovery for a large class of materials
+including metals, ceramics, and proteins.",1912.11582v1
+2020-02-29,Role of intermediate 4$f$ states in tuning the band structure of high entropy oxides,"High entropy oxides (HEOs) are single phase solid solutions consisting of 5
+or more cations in approximately equiatomic proportions. In this study, we show
+reversible control of optical properties in a rare-earth (RE) based
+HEO-(Ce$_{0.2}$La$_{0.2}$Pr$_{0.2}$Sm$_{0.2}$Y$_{0.2}$)O$_{2-\delta}$ and
+subsequently utilize a combination of spectroscopic techniques to derive the
+features of the electronic band structure underpinning the observed optical
+phenomena. Heat treatment of the HEO under vacuum atmosphere followed by
+reheat-treatment in air results in a reversible change of the band gap energy,
+from 1.9 eV to 2.5 eV. The finding is consistent with the reversible changes in
+the oxidation state and related $f$-orbital occupancy of Pr. However, no
+pertinent changes in the phase composition or crystal structure is observed
+upon the vacuum heat treatment. Further annealing of this HEO under H$_2$
+atmosphere, followed by reheat-treatment in air, results in even larger but
+still reversible change of the band gap energy from 1.9 eV to 3.2 eV. This is
+accompanied by a disorder-order type crystal structure transition and changes
+in the O 2$p$-RE 5$d$ hybridization evidenced from X-ray absorption near edge
+spectra (XANES). The O $K$ and RE ${M_{4,5}}$/$L_{3}$ XANES indicate that the
+presence of Ce and Pr (in 3+/4+) state leads to the formation of intermediate
+4$f$ energy levels between the O 2$p$ and RE 5$d$ gap in HEO. It is concluded
+that heat treatment under reducing/oxidizing atmospheres affects these
+intermediate levels, thus, offering the possibility to tune the band gap energy
+in HEO.",2003.00268v1
+2020-06-11,Tunable Photodetectors via in situ Thermal Conversion of TiS$_3$ to TiO$_2$,"In two-dimensional materials research, oxidation is usually considered as a
+common source for the degradation of electronic and optoelectronic devices or
+even device failure. However, in some cases a controlled oxidation can open the
+possibility to widely tune the band structure of 2D materials. In particular,
+we demonstrate the controlled oxidation of titanium trisulfide (TiS$_3$), a
+layered semiconductor that has attracted much attention recently thanks to its
+quasi-1D electronic and optoelectronic properties and its direct bandgap of 1.1
+eV. Heating TiS$_3$ in air above 300 {\deg}C gradually converts it into
+TiO$_2$, a semiconductor with a wide bandgap of 3.2 eV with ap-plications in
+photo-electrochemistry and catalysis. In this work, we investigate the
+controlled thermal oxidation of individual TiS$_3$ nanoribbons and its
+influence on the optoelectronic properties of TiS$_3$-based photodetectors. We
+observe a step-wise change in the cut-off wavelength from its pristine value
+~1000 nm to 450 nm after subjecting the TiS$_3$ devices to subsequent thermal
+treatment cycles. Ab-initio and many-body calculations confirm an increase in
+the bandgap of titanium oxysulfide (TiO$_{2-x}$S$_x$) when increasing the
+amount of oxygen and reducing the amount of sulfur.",2006.06842v1
+2020-08-11,Analytical Approach to Phonon Calculations in the SCC-DFTB Framework,"Detailed derivation of the analytical, reciprocal-space approach of Hessian
+calculation within the self-consistent-charge density functional based
+tight-binding framework (SCC-DFTB) is presented. This approach provides an
+accurate and efficient way for obtaining the SCC-DFTB Hessian of periodic
+systems. Its superiority with respect to the traditional numerical force
+differentiation method is demonstrated for doped graphene, graphene
+nanoribbons, boron-nitride nanotubes, bulk zinc-oxide and other systems.",2008.04642v1
+2020-09-29,The iron record of asteroidal processes in carbonaceous chondrites,"The valence of iron has been used in terrestrial studies to trace the
+hydrolysis of primary silicate rocks. Here, we use a similar approach to
+characterize the secondary processes, namely thermal metamorphism and aqueous
+alteration, that have affected carbonaceous chondrites. X-ray absorption
+near-edge structure spectroscopy at the Fe-K- edge was performed on a series of
+36 CM, 9 CR, 10 CV, and 2 CI chondrites. Among the four carbonaceous chondrites
+groups studied, a correlation between the iron oxidation index (IOI = [2
+((Fe2+) + 3(Fe3+))/FeTOT) and the hydrogen content is observed. However, within
+the CM group, for which a progressive alteration sequence has been defined, a
+conversion of Fe3+ to Fe2+ is observed with increasing degree of aqueous
+alteration. This reduction of iron can be explained by an evolution in the
+mineralogy of the secondary phases. In the case of the few CM chondrites that
+experienced some thermal metamorphism, in addition to aqueous alteration, a
+redox memory of the aqueous alteration is present: a significant fraction of 3+
+2+ 0 Fe is present, together with Fe and sometimes Fe. From our data set, the
+CR chondrites show a wider range of IOI from 1.5 to 2.5. In all considered CR
+chondrites, the three oxidation states of iron coexist. Even in the
+least-altered CR chondrites, the fraction of Fe3+ can be high (30% for MET
+00426). This observation confirms that oxidized iron has been integrated during
+formation of fine-grained amorphous material in the matrix. Last, the IOI of CV
+chondrites does not reflect the reduced/oxidized classification based on metal
+and magnetite proportions, but is strongly correlated with petrographic types.
+The valence of iron in CV chondrites therefore appears to be most closely
+related to thermal history, rather than aqueous alteration, even if these
+processes can occur together .",2009.13950v2
+2020-10-09,Theoretical Modelling of High-Resolution X-Ray Absorption Spectra at Uranium M4 Edge,"We investigate the origin of satellite features that appear in the
+high-resolution x-ray absorption spectra measured at the uranium M 4 edge in
+compounds where the uranium atoms are in the U 6+ oxidation state. We employ a
+material-specific Anderson impurity model derived from the electronic structure
+obtained by the density-functional theory.",2010.04410v1
+2020-10-14,Reversible and irreversible processes during cyclic voltammetry of an electrodeposited manganese oxide as catalyst for the oxygen evolution reaction,"Manganese oxides have received much attention over the years among the wide
+range of electrocatalysts for the oxygen evolution reaction (OER) due to their
+low toxicity, high abundance and rich redox chemistry. While many previous
+studies focused on the activity of these materials, a better understanding of
+the material transformations relating to activation or degradation is highly
+desirable, both from a scientific perspective and for applications. We
+electrodeposited Na-containing MnOx without long-range order from an alkaline
+solution to investigate these aspects by cyclic voltammetry, scanning electron
+microscopy and x-ray absorption spectroscopy at the Mn-K and Mn-L edges. The
+pristine film was assigned to a layered edge-sharing Mn3+/4+ oxide with Mn-O
+bond lengths of mainly 1.87 {\AA} and some at 2.30 {\AA} as well as Mn-Mn bond
+lengths of 2.87 {\AA} based on fits to the extended x-ray fine structure. The
+decrease of the currents at voltages before the onset of the OER followed power
+laws with three different exponents depending on the number of cycles and the
+Tafel slope decreases from 186 \pm 48 to 114 \pm 18 mV dec-1 after 100 cycles,
+which we interpret in the context of surface coverage with unreacted
+intermediates. Post-mortem microscopy and bulk spectroscopy at the Mn-K edge
+showed no change of the microstructure, bulk local structure or bulk Mn
+valence. Yet, the surface region of MnOx oxidized toward Mn4+, which explains
+the reduction of the currents in agreement with literature. Surprisingly, we
+find that MnOx reactivates after 30 min at open-circuit (OC), where the
+currents and also the Tafel slope increase. Reactivation processes during OC
+are crucial because OC is unavoidable when coupling the electrocatalysts to
+intermittent power sources such as solar energy for sustainable energy
+production.",2010.06957v1
+2021-02-06,Aluminum Oxide at the Monolayer Limit via Oxidant-free Plasma-Assisted Atomic Layer Deposition on GaN,"Atomic layer deposition (ALD) is an essential tool in semiconductor device
+fabrication that allows the growth of ultrathin and conformal films to
+precisely form heterostructures and tune interface properties. The
+self-limiting nature of the chemical reactions during ALD provides excellent
+control over the layer thickness. However, in contrast to idealized growth
+models, it is experimentally challenging to create continuous monolayers by ALD
+because surface inhomogeneities and precursor steric interactions result in
+island growth during film nucleation. Thus, the ability to create pin-hole free
+monolayers by ALD would offer new opportunities for controlling interfacial
+charge and mass transport in semiconductor devices, as well as for tailoring
+surface chemistry. Here, we report full encapsulation of c-plane gallium
+nitride (GaN) with an ultimately thin (~3 {\AA}) aluminum oxide (AlOx)
+monolayer, which is enabled by the partial conversion of the GaN surface oxide
+into AlOx using a combination of trimethylaluminum deposition and hydrogen
+plasma exposure. Introduction of monolayer AlOx significantly modifies the
+physical and chemical properties of the surface, decreasing the work function
+and introducing new chemical reactivity to the GaN surface. This tunable
+interfacial chemistry is highlighted by the reactivity of the modified surface
+with phosphonic acids under standard conditions, which results in
+self-assembled monolayers with densities approaching the theoretical limit.
+More broadly, the presented monolayer AlOx deposition scheme can be extended to
+other dielectrics and III-V-based semiconductors, with significant relevance
+for applications in optoelectronics, chemical sensing, and
+(photo)electrocatalysis.",2102.03642v1
+2021-03-10,Solid phase epitaxial growth of the correlated-electron transparent conducting oxide SrVO3,"SrVO3 thin films with a high figure of merit for applications as transparent
+conductors were crystallized from amorphous layers using solid phase epitaxy
+(SPE). Epitaxial SrVO3 films crystallized on SrTiO3 using SPE exhibit a room
+temperature resistivity of 2.5 x 10-5 Ohms cm, a residual resistivity ratio of
+3.8, and visible light transmission above 0.5 for a 60 nm-thick film. SrVO3
+layers were deposited at room temperature using radio-frequency sputtering in
+an amorphous form and subsequently crystallized by heating in controlled gas
+environment. The lattice parameters and mosaic angular width of x-ray
+reflections from the crystallized films are consistent with partial relaxation
+of the strain resulting from the epitaxial mismatch between SrVO3 and SrTiO3. A
+reflection high-energy electron diffraction study of the kinetics of SPE
+indicates that crystallization occurs via the thermally activated propagation
+of the crystalline/amorphous interface, similar to SPE phenomena in other
+perovskite oxides. Thermodynamic calculations based on density functional
+theory predict the temperature and oxygen partial pressure conditions required
+to produce the SrVO3 phase and are consistent with the experiments. The
+separate control of deposition and crystallization conditions in SPE presents
+new possibilities for the crystallization of transparent conductors in complex
+geometries and over large areas.",2103.05797v2
+2021-05-20,Paring density waves as the origin of a ring-like RIXS profile in Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$,"The coexistence of a homogeneous d-wave gap and short-ranged pairing density
+waves (PDW) accounts for the apparent ""ring"" charge order in all directions of
+the copper oxide plane, observed by recent RIXS measurements in
+Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$",2105.09692v1
+2021-05-21,Laboratory blueprints for interstellar searches of aromatic chiral molecules: rotational signatures of styrene oxide,"The tracking of symmetry-breaking events in space is a longlasting goal of
+astrochemists, aiming at an understanding of homochiral Earth chemistry. One
+current effort at this frontier aims at the detection of small chiral molecules
+in the interstellar medium. For that, high-resolution laboratory spectroscopy
+data is required, providing blueprints for the search and assignment of these
+molecules using radioastronomy. Here, we used chirped-pulse Fourier transform
+microwave and millimeter-wave spectroscopy and frequency modulation absorption
+spectroscopy to record and assign the rotational spectrum of the chiral
+aromatic molecule styrene oxide, $\mathrm{C_{6}H_{5}C_{2}H_{3}O}$, a relevant
+candidate for future radioastronomy searches. Using experimental data from the
+2-12, 75-110, 170-220, and 260-330 GHz regions, we performed a global spectral
+analysis, complemented by quantum chemistry calculations. A global fit of the
+ground state rotational spectrum was obtained, including rotational transitions
+from all four frequency regions. Primary rotational constants as well as
+quartic and sextic centrifugal distortion constants were determined. We also
+investigated vibrationally excited states of styrene oxide, and for the three
+lowest vibrational states, we determined rotational constants including
+centrifugal distortion corrections up to the sextic order. In addition,
+spectroscopic parameters for the singly-substituted $^{13}$C and $^{18}$O
+isotopologues were retrieved from the spectrum in natural abundance and used to
+determine the effective ground state structure of styrene oxide in the gas
+phase. The spectroscopic parameters and line lists of rotational transitions
+obtained here will assist future astrochemical studies of this class of chiral
+organic molecules.",2105.11337v1
+2021-06-24,Time-resolved diffraction and photoelectron spectroscopy investigation of the reactive molecular beam epitaxy of $\mathrm{Fe_3O_4}$ ultrathin films,"We present time-resolved high energy x-ray diffraction (tr-HEXRD),
+time-resolved hard x-ray photoelectron spectroscopy (tr-HAXPES) and
+time-resolved grazing incidence small angle x-ray scattering (tr-GISAXS) data
+of the reactive molecular beam epitaxy (RMBE) of $\mathrm{Fe_3O_4}$ ultrathin
+films on various substrates. Reciprocal space maps are recorded during the
+deposition of $\mathrm{Fe_3O_4}$ on $\mathrm{SrTiO_3(001)}$, MgO(001) and
+NiO/MgO(001) in order to observe the temporal evolution of Bragg reflections
+sensitive to the octahedral and tetrahedral sublattices of the inverse spinel
+structure of $\mathrm{Fe_3O_4}$. A time delay between the appearance of rock
+salt and spinel-exclusive reflections reveals that first, the iron oxide film
+grows with $\mathrm{Fe_{1-\delta}O}$ rock salt structure with exclusive
+occupation of octahedral lattice sites. When this film is 1.1$\,$nm thick, the
+further growth of the iron oxide film proceeds in the inverse spinel structure,
+with both octahedral and tetrahedral lattice sites being occupied. In addition,
+iron oxide on $\mathrm{SrTiO_3(001)}$ initially grows with none of these
+structures. Here, the formation of the rock salt structure starts when the film
+is 1.5$\,$nm thick. This is confirmed by tr-HAXPES data obtained during growth
+of iron oxide on $\mathrm{SrTiO_3(001)}$, which demonstrate an excess of
+$\mathrm{Fe^{2+}}$ cations in growing films thinner than 3.2$\,$nm. This rock
+salt phase only appears during growth and vanishes after the supply of the Fe
+molecular beam is stopped. Thus, it can be concluded the rock salt structure of
+the interlayer is a property of the dynamic growth process. The tr-GISAXS data
+link these structural results to an island growth mode of the first 2-3$\,$nm
+on both MgO(001) and $\mathrm{SrTiO_3(001)}$ substrates.",2106.13192v1
+2021-09-27,Structure-Property-Performance Relationships of Cuprous Oxide Nanostructures for Dielectric Mie Resonance-Enhanced Photocatalysis,"Nanostructured metal oxides, such as Cu2O, CeO2, {\alpha}-Fe2O3, and TiO2 can
+efficiently mediate photocatalysis for solar-to-chemical energy conversion and
+pollution remediation. In this contribution, we report a novel approach,
+dielectric Mie resonance-enhanced photocatalysis, to enhance the catalytic
+activity of metal oxide photocatalysts. Specifically, we demonstrate that Cu2O
+nanostructures exhibiting dielectric Mie resonances can exhibit up to an order
+of magnitude higher photocatalytic rate as compared to Cu2O nanostructures not
+exhibiting dielectric Mie resonances. Our finite-difference time-domain (FDTD)
+simulation and experimental results predict a volcano-type relationship between
+the photocatalytic rate and the size of Cu2O nanospheres and nanocubes. Using
+transient absorption measurements, we reveal that a coherent electronic process
+associated with dielectric Mie resonance-mediated charge carrier generation is
+dominant in Cu2O nanostructures that exhibit higher photocatalytic rates.
+Although we experimentally demonstrate dielectric Mie resonance-enhanced
+photocatalysis using Cu2O particles here, based on our FDTD simulations, we
+anticipate the same can be achieved with other metal oxide photocatalysts,
+including CeO2, {\alpha}-Fe2O3, and TiO2.",2109.13332v2
+2021-12-15,"Recent progress of fabrication, characterization, and applications of anodic aluminum oxide (AAO) membrane: A review","The progress of membrane technology with the development of membranes with
+controlled parameters led to porous membranes. These membranes can be formed
+using different methods and have numerous applications in science and
+technology. Anodization of aluminum in this aspect is an electro-synthetic
+process that changes the surface of the metal through oxidation to deliver an
+anodic oxide layer. This process results in a self-coordinated, exceptional
+cluster of round and hollow formed pores with controllable pore widths,
+periodicity, and thickness. After the initial introduction, the paper proceeds
+with a brief overview of anodizing process. That engages anodic aluminum oxide
+(AAO) layers to be used as formats in various nanotechnology applications
+without the necessity for expensive lithographical systems. This review article
+surveys the current status of the investigation on AAO membranes. A
+comprehensive analysis is performed on AAO membranes in applications;
+filtration, sensors, drug delivery, template-assisted growth of various
+nanostructures. Their multiple usages in nanotechnology have also been
+discussed to gather nanomaterials and devices or unite them into specific
+applications, such as nano-electronic gadgets, channel layers, and clinical
+platforms tissue designing. From this review, the fact that the specified
+enhancement of properties of AAO can be done by varying geometric parameters of
+AAO has been highlighted. No review paper focused on a detailed discussion of
+applications of AAO with prospects and challenges. This review paper represents
+the formation, properties, applications with objective consideration of the
+prospects and challenges of AAO applications. The prospects may appeal to
+researchers to promote the development of unique membranes with
+functionalization and controlled geometric parameters and check the feasibility
+of the AAO membranes in nano-devices.",2112.08450v1
+2022-02-10,Monte-Carlo Multiscale Simulation Study of Argon Adsorption/Desorption Hysteresis in Mesoporous Heterogeneous Tubular Pores like MCM-41 or Oxidized Porous Silicon,"In a recent paper [J. Chem. Phys. 127, 154701 (2007)], a multiscale approach
+was introduced which allowed the calculation of adsorption/desorption
+hysteresis for fluid confined in a single",2202.04900v1
+2022-06-16,New hybrid organic-inorganic ferrophotovoltaic perovskites nanoparticles with high voltage for indoor and IoT applications,"The ideal band gap for a photovoltaic active layer for the solar spectrum is
+around 1.3 eV. However oxides with such values are rare. One of the most
+studied oxides to date as a photovoltaic active layer is the cuprous oxide
+Cu2O. Its band gap is around 2.1 eV and is therefore not ideal for the solar
+spectrum. Power Conversion Efficiency generally do not exceed 4%. In this paper
+we propose to study an emerging type of solar cell that is based on
+ferroelectricity. In this type of solar cell, a p-n junction is not necessarily
+required, unlike conventional solar cells. Interesting conversion efficiencies
+are beginning to be obtained with this type of cell, however the mechanisms are
+still not well understood and several material and engineering challenges must
+be addressed. The objective of this paper is to initiate an innovative
+photovoltaic technology based on novel inorganic with suitable bandgap widths
+and organic materials (biopolymer). These oxides are more stables. We
+synthesized ferroelectric materials that absorb a large part of the solar
+spectrum with reduced bandgap widths. PZN-4.5PT nanoparticles were dispersed in
+a biopolymer matrix. Hybrid thin films with these inorganic nanoparticles
+embedded in a biopolymer have been successfully fabricated by spin coating on
+ITO substrate. Structural, morphological and electrical properties were
+investigated. The best Power Conversion Efficiencies measure under a light LED
+illumination of 3550 lux are respectively 21.83 % and 31.62 % for 15 and 30 min
+light exposition with an open-circuit voltage of 5.17 and 5.86 V.",2207.03340v1
+2022-06-25,Advances in honeycomb layered oxides: Part I -- Syntheses and Characterisations of Pnictogen- and Chalcogen-Based Honeycomb Layered Oxides,"Advancements in nanotechnology continue to unearth material vistas that
+presage a new age of revolutionary functionalities replete with unparalleled
+physical properties and avant-garde chemical capabilities that promise sweeping
+paradigm shifts in energy, environment, telecommunications and potentially
+healthcare. At the upper echelons of this realm, the pnictogen and chalcogen
+class of honeycomb layered oxides have emerged with fascinating crystal
+chemistry and exotic electromagnetic and topological phenomena that muster
+multifaceted concepts spanning from materials science to condensed matter
+physics and potential applications in electrochemistry, quantum mechanics and
+electronics. In a bid to shed light on the mechanisms governing these
+biomimetic nanostructures, this review highlights the significant milestones
+and breakthroughs that have augmented their current fundamental theory,
+properties, and utilities. Herein, we elucidate the vast promising crystal
+chemistry space against the backdrop of known synthesis and characterisation
+techniques employed in the development and optimisation of this class of
+honeycomb layered oxides. Further, we highlight key theoretical models that
+have reinvigorated the exploration and characterisation of within this class of
+materials and are poised to redefine the frontiers of material research and
+their applications. We conclude by envisaging future research directions where
+fascinating physicochemical, topological and electromagnetic properties could
+be lurking and where valiant efforts ought to be inclined, particularly in the
+prospective realisation of exotic material compositional space as well as their
+utility as testing grounds for emergent two-dimensional (2D) topological
+quantum gravity and conformal field theories.",2207.06499v4
+2022-07-20,Anatomy of rocky planets formed by rapid pebble accretion I. How icy pebbles determine the core fraction and FeO contents,"We present a series of papers dedicated to modelling the accretion and
+differentiation of rocky planets that form by pebble accretion within the
+lifetime of the protoplanetary disc. In this first paper, we focus on how the
+accreted ice determines the distribution of iron between the mantle (oxidized
+FeO and FeO$_{1.5}$) and the core (metallic Fe and FeS). We find that an
+initial primitive composition of ice-rich material leads, upon heating by the
+decay of $^{26}$Al, to extensive water flow and the formation of clay minerals
+inside planetesimals. Metallic iron dissolves in liquid water and precipitates
+as oxidized magnetite Fe$_3$O$_4$. Further heating by $^{26}$Al destabilizes
+the clay at a temperature of around 900 K. The released supercritical water
+ejects the entire water content from the planetesimal. Upon reaching the
+silicate melting temperature of 1,700 K, planetesimals further differentiate
+into a core (made mainly of iron sulfide FeS) and a mantle with a high fraction
+of oxidized iron. We propose that the asteroid Vesta's significant FeO fraction
+in the mantle is a testimony of its original ice content. We consider Vesta to
+be a surviving member of the population of protoplanets from which Mars, Earth,
+and Venus grew by pebble accretion. We show that the increase in the core mass
+fraction and decrease in FeO contents with increasing planetary mass (in the
+sequence Vesta -- Mars -- Earth) is naturally explained by the growth of
+terrestrial planets outside of the water ice line through accretion of pebbles
+containing iron that was dominantly in metallic form with an intrinsically low
+oxidation degree.",2207.09795v2
+2022-07-20,"Anatomy of rocky planets formed by rapid pebble accretion III. Partitioning of volatiles between planetary core, mantle, and atmosphere","Volatile molecules containing hydrogen, carbon, and nitrogen are key
+components of planetary atmospheres. In the pebble accretion model for rocky
+planet formation, these volatile species are accreted during the main planetary
+formation phase. For this study, we modelled the partitioning of volatiles
+within a growing planet and the outgassing to the surface. The core stores more
+than 90\% of the hydrogen and carbon budgets of Earth for realistic values of
+the partition coefficients of H and C between metal and silicate melts. The
+magma oceans of Earth and Venus are sufficiently deep to undergo oxidation of
+ferrous Fe$^{2+}$ to ferric Fe$^{3+}$. This increased oxidation state leads to
+the outgassing of primarily CO$_2$ and H$_2$O from the magma ocean of Earth. In
+contrast, the oxidation state of Mars' mantle remains low and the main
+outgassed hydrogen carrier is H$_2$. This hydrogen easily escapes the
+atmosphere due to the irradiation from the young Sun in XUV wavelengths,
+dragging with it the majority of the CO, CO$_2$, H$_2$O, and N$_2$ contents of
+the atmosphere. A small amount of surface water is maintained on Mars, in
+agreement with proposed ancient ocean shorelines, for moderately low values of
+the mantle oxidation. Nitrogen partitions relatively evenly between the core
+and the atmosphere due to its extremely low solubility in magma; the burial of
+large reservoirs of nitrogen in the core is thus not possible. The overall low
+N contents of Earth disagree with the high abundance of N in all chondrite
+classes and favours a volatile delivery by pebble snow. Our model of rapid
+rocky planet formation by pebble accretion displays broad consistency with the
+volatile contents of the Sun's terrestrial planets. The diversity of the
+terrestrial planets can therefore be used as benchmark cases to calibrate
+models of extrasolar rocky planets and their atmospheres.",2207.09807v2
+2022-08-03,Electron spin transport in a metal-oxide-semiconductor Si two-dimensional inversion channel: Effect of hydrogen annealing on spin scattering mechanism and spin lifetime,"Department of Electrical Engineering and Information Systems, The University
+of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan Center for Spintronics
+Research Network (CSRN), The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo
+113-8656, Japan",2208.01798v1
+2022-09-27,Understanding the growth mechanism of BaZrS$_3$ chalcogenide perovskite thin films from sulfurized oxide precursors,"Barium zirconium sulfide (BaZrS3) is an earth-abundant and environmentally
+friendly chalcogenide perovskite with promising properties for various energy
+conversion applications. Recently, sulfurization of oxide precursors has been
+suggested as a viable solution for effective synthesis, especially from the
+perspective of circumventing the difficulty of handling alkali earth metals. In
+this work, we explore in detail the synthesis of BaZrS3 from Ba-Zr-O oxide
+precursor films sulfurized at temperatures ranging from 700 {\deg}C to 1000
+{\deg}C. We propose a formation mechanism of BaZrS3 based on a two-step
+reaction involving an intermediate amorphization step of the BaZrO3 crystalline
+phase. We show how the diffusion of sulfur (S) species in the film is the
+rate-limiting step of this reaction. The processing temperature plays a key
+role in determining the total fraction of conversion from oxide to sulfide
+phase at a constant flow rate of the sulfur-containing H2S gas used as a
+reactant. Finally, we observe the formation of stoichiometric BaZrS3 (1:1:3),
+even under Zr-rich precursor conditions, with the formation of ZrO2 as a
+secondary phase. This marks BaZrS3 quite unique among the other types of
+chalcogenides, such as chalcopyrites and kesterites, which can instead
+accommodate quite a large range of non-stoichiometric compositions. This work
+opens up a pathway for further optimization of the BaZrS3 synthesis process,
+straightening the route towards future applications of this material.",2209.13478v4
+2022-10-05,Direct evidence of a charge depletion region at the interface of Van der Waals monolayers and dielectric oxides: The case of superconducting FeSe/STO,"The discovery of two dimensional Van der Waals materials has opened up
+several possibilities for designing novel devices. Yet a more promising way of
+designing exotic heterostutures with improved physical properties is to grow a
+monolayer of these materials on a substrate. For example, in the field of
+superconductivity it has been demonstrated that the superconducting transition
+temperature of a monolayer of FeSe grown on some oxide substrates e.g.,
+strontium titanate (STO) is by far higher than its bulk counterpart. Although
+the system has been considered as a model system for understanding the
+phenomenon of high-temperature superconductivity, the physical mechanism
+responsible for this high transition temperature is still highly under debate.
+Here using momentum and energy resolved high-resolution electron energy-loss
+spectroscopy we probe the dynamic charge response of the FeSe/STO(001) system
+and demonstrate that the frequency- and momentum-dependent dynamic charge
+response is not compatible with a simple film/substrate model. Our analysis
+reveals the existence of a depletion region at the interface between this Van
+der Waals monolayer and the substrate. The presence of the depletion layer,
+accompanied with a considerably large charge transfer from STO into the FeSe
+monolayer, leads to a strong renormalization of the STO energy bands and a
+substantial band bending at the interface. Our results shed light on the
+electronic complexities of the FeSe/oxide interfaces and pave the way of
+designing novel low-dimensional high-temperature superconductors through
+interface engineering. We anticipate that the observed phenomenon is rather
+general and can take place in many two dimensional Van der Waals monolayers
+brought in contact with dielectric oxides or semiconducting substrates.",2210.02058v1
+2022-10-21,"MnEdgeNet -- Accurate Decomposition of Mixed Oxidation States for Mn XAS and EELS L2,3 Edges without Reference and Calibration","Accurate decomposition of the mixed Mn oxidation states is highly important
+for characterizing the electronic structures, charge transfer, and redox
+centers for electronic, electrocatalytic, and energy storage materials that
+contain Mn. Electron energy loss spectroscopy (EELS) and soft X-ray absorption
+spectroscopy (XAS) measurements of the Mn L2,3 edges are widely used for this
+purpose. To date, although the measurement of the Mn L2,3 edges is
+straightforward given the sample is prepared properly, an accurate
+decomposition of the mix valence states of Mn remains non-trivial. For both
+EELS and XAS, 2+, 3+, 4+ reference spectra need to be taken on the same
+instrument/beamline and preferably in the same experimental session because the
+instrumental resolution and the energy axis offset could vary from one session
+to another. To circumvent this hurdle, in this study, we adopted a deep
+learning approach and developed a calibration-free and reference-free method to
+decompose the oxidation state of Mn L2,3 edges for both EELS and XAS. To
+synthesize physics-informed and ground-truth labeled training datasets, we
+created a forward model that takes into account plural scattering,
+instrumentation broadening, noise, and energy axis offset. With that, we
+created a 1.2 million-spectrum database with a three-element oxidation state
+composition label. The library includes a sufficient variety of data including
+both EELS and XAS spectra. By training on this large database, our
+convolutional neural network achieves 85% accuracy on the validation dataset.
+We tested the model and found it is robust against noise (down to PSNR of 10)
+and plural scattering (up to t/{\lambda} = 1). We further validated the model
+against spectral data that were not used in training.",2210.11657v1
+2022-11-18,Investigation of the SiO2-SiC interface using low energy muon spin rotation spectroscopy,"Using positive muons as local probes implanted at low energy enables
+gathering information about the material of interest with nanometer depth
+resolution (low energy muon spin rotation spectroscopy (LE-$\mu$SR). In this
+work, we leverage the capabilities of LE-$\mu$SR to perform an investigation of
+the SiO$_\text{2}$-SiC interface. Thermally oxidized samples are investigated
+before and after annealing in nitric oxide (NO) and argon (Ar) ambience.
+Thermal oxidation is found to result in structural changes both in the SiC
+crystal close to the interface and at the interface itself. Annealing in NO
+environment is known to passivate the defects leading to a reduction of the
+density of interface traps (D$_{it}$); LE-$\mu$SR further reveals that the NO
+annealing results in a thin layer of high carrier concentration in SiC,
+extending to more than 50 nm depending on the annealing conditions. We also see
+indications of Si vacancy (V$_{Si}$) formation in SiC after thermal oxidation.
+Following NO annealing, nitrogen occupies the V$_{Si}$ sites, leading to the
+reduction in D$_{it}$ and at the same time, creating a charge-carrier-rich
+region near the interface. By comparing the LE-$\mu$SR data from a sample with
+known doping density, we perform a high-resolution quantification of the free
+carrier concentration near the interface after NO annealing and discuss the
+origin of observed near-surface variations. Finally, the depletion of carriers
+in a MOS capacitor in the region below the interface is shown using LE-$\mu$SR.
+The NO annealed sample shows the narrowest depletion region, likely due to the
+reduced D$_{it}$ and charge-carrier-rich region near the interface. Our
+findings demonstrate the many benefits of utilizing LE-$\mu$SR to study
+critical regions of semiconductor devices that have been inaccessible with
+other techniques while retaining nanoscale depth resolution and a
+non-destructive approach.",2211.10252v1
+2022-11-28,Nitrous Oxide and Climate,"Higher concentrations of atmospheric nitrous oxide (N2O) are expected to
+slightly warm Earth's surface because of increases in radiative forcing.
+Radiative forcing is the difference in the net upward thermal radiation flux
+from the Earth through a transparent atmosphere and radiation through an
+otherwise identical atmosphere with greenhouse gases. Radiative forcing,
+normally measured in W/m^2, depends on latitude, longitude and altitude, but it
+is often quoted for the tropopause, about 11 km of altitude for temperate
+latitudes, or for the top of the atmosphere at around 90 km. For current
+concentrations of greenhouse gases, the radiative forcing per added N2O
+molecule is about 230 times larger than the forcing per added carbon dioxide
+(CO2) molecule. This is due to the heavy saturation of the absorption band of
+the relatively abundant greenhouse gas, CO2, compared to the much smaller
+saturation of the absorption bands of the trace greenhouse gas N2O. But the
+rate of increase of CO2 molecules, about 2.5 ppm/year (ppm = part per million
+by mole), is about 3000 times larger than the rate of increase of N2O
+molecules, which has held steady at around 0.00085 ppm/year since 1985. So, the
+contribution of nitrous oxide to the annual increase in forcing is 230/3000 or
+about 1/13 that of CO2. If the main greenhouse gases, CO2, CH4 and N2O have
+contributed about 0.1 C/decade of the warming observed over the past few
+decades, this would correspond to about 0.00064 K per year or 0.064 K per
+century of warming from N2O. Proposals to place harsh restrictions on nitrous
+oxide emissions because of warming fears are not justified by these facts.
+Restrictions would cause serious harm; for example, by jeopardizing world food
+supplies.",2211.15780v1
+2022-12-02,Deposition of Reduced Graphene Oxide Thin Film by Spray Pyrolysis Method for Perovskite Solar Cell,"The Perovskite absorber layer, the electron transport layer (ETL), the hole
+transport layer (HTL), and the transparent conducting oxide layer (TCO) are the
+major components that make up a Perovskite solar cell. Between ETL and HTL, the
+absorber layer is sandwiched, on which electron-hole pairs are created after
+absorption of solar radiation. Despite substantial progress toward efficiency,
+long-term stability still remains a serious concern. Present work focuses
+toward contributing on the later issue by adopting Titanium dioxide (TiO2) as
+ETL and reduced graphene oxide (rGO) as HTL. Specifically, in the present work,
+we report our efforts on the preparation of compact titanium dioxide (C-TiO2)
+and mesoporous titanium dioxide (M-TiO2) layers as an ETL and a reduced
+graphene oxide thin film as a HTL. The C-TiO2 film was spin casted on FTO glass
+followed by casting of M-TiO2 film using Doctor Blading technique. Similarly,
+the rGO film was produced by spray casting over the glass substrate. The
+as-prepared ETL and HTL layers were characterized by measuring their optical
+properties (transmittance and reflectance of thin films). Then, the bandgap, Eg
+was extracted from reflectance and transmittance curves for ETL and HTL
+respectively. In the case of rGO, we found the value of Eg to be 2.1 eV, which
+varies between 2.7eV and 0.02eV depending upon its reduction level based on the
+previously reported values. Similarly, the bandgap of the C-TiO2 was 4.51 eV
+which was reduced to 4.12 eV after the addition of M-TiO2, which are 0.9 to 1.1
+eV higher than previously reported values. However, bandgap shows decreasing
+trend after employing M- TiO2 over C-TiO2. In a Perovskite solar cell, both ETL
+and HTL will be investigated.",2212.01066v1
+2023-01-11,Chemical profiles of the oxides on tantalum in state of the art superconducting circuits,"Over the past decades, superconducting qubits have emerged as one of the
+leading hardware platforms for realizing a quantum processor. Consequently,
+researchers have made significant effort to understand the loss channels that
+limit the coherence times of superconducting qubits. A major source of loss has
+been attributed to two level systems that are present at the material
+interfaces. We recently showed that replacing the metal in the capacitor of a
+transmon with tantalum yields record relaxation and coherence times for
+superconducting qubits, motivating a detailed study of the tantalum surface. In
+this work, we study the chemical profile of the surface of tantalum films grown
+on c-plane sapphire using variable energy X-ray photoelectron spectroscopy
+(VEXPS). We identify the different oxidation states of tantalum that are
+present in the native oxide resulting from exposure to air, and we measure
+their distribution through the depth of the film. Furthermore, we show how the
+volume and depth distribution of these tantalum oxidation states can be altered
+by various chemical treatments. By correlating these measurements with detailed
+measurements of quantum devices, we can improve our understanding of the
+microscopic device losses.",2301.04567v2
+2023-02-08,Bioabsorbable WE43 Mg alloy wires modified by continuous plasma electrolytic oxidation for implant applications. Part II: degradation and biological performance,"The corrosion, mechanical degradation and biological performance of
+cold-drawn WE43 Mg wires were analyzed as a function of thermo-mechanical
+processing and the presence of a protective oxide layer created by continuous
+plasma electrolytic oxidation (PEO). It was found that the corrosion properties
+of the non-surface-treated wire could be optimized by means of thermal
+treatment within certain limits, but the corrosion rate remained very high.
+Hence, strength and ductility of these wires vanished after 24 h of immersion
+in simulated body fluid at 37$^\circ$C and, as a result of that rather quick
+degradation, direct tests did not show any MC3T3-E1 preosteoblast cell
+attachment on the surface of the Mg wires. In contrast, surface modification of
+the annealed WE43 Mg wires by a continuous PEO process led to the formation of
+a homogeneous oxide layer of $\approx$ 8$\mu$m and significantly improved the
+corrosion resistance and hence the biocompatibility of the WE43 Mg wires. It
+was found that a dense layer of Ca/P was formed at the early stages of
+degradation on top of the Mg(OH)2 layer and hindered the diffusion of the
+Cl-ions which dissolve Mg(OH)2 and accelerate the corrosion of Mg alloys. As a
+result, pitting corrosion was suppressed and the strength of the Mg wires was
+above 100 MPa after 96 h of immersion in simulated body fluid at 37$^\circ$C.
+Moreover, many cells were able to attach on the surface of the PEO
+surface-modified wires during cell culture testing. These results demonstrate
+the potential of thin Mg wires surface-modified by continuous PEO in terms of
+mechanical, degradation and biological performance for bioabsorbable wire-based
+devices.",2302.13778v1
+2023-05-25,Structure and properties of the films based on ternary transition metal borides: theory and experiment,"The review presents the results of theoretical and experimental studies of
+the structure, bonding between atoms, mechanical properties, thermal stability,
+and oxidation and corrosion resistance of films based on ternary transition
+metal borides.",2305.15854v1
+2023-06-11,Imaging emergent exotic quasiparticle state in a frustrated transition metal oxide,"The existence of rich Fermiology in anomalous metal phase in exotic
+superconductors has attracted considerable interests, as exemplified in copper,
+iron-based, and intermetallic frustrated kagome-based compounds. A common
+feature in these cases is pseudo-gap opening or long-range lattice/electronic
+ordering above superconducting critical temperature Tc. As yet developed area
+is the potential existence of exotic Fermiology in superconducting transition
+metal oxides on a geometrically frustrated lattice. Here, we focus on the
+spinel oxide superconductor LiTi2O4, which can be viewed as the hole-doped side
+of the orbital ordered 3d1 Mott system on the Ti-derived pyrochlore frustrated
+network. By the in-situ combination of angle-resolved photoemission
+spectroscopy (ARPES) and epitaxial thin film growth, we discovered the abrupt
+flattening of near Fermi energy dispersion below the characteristic temperature
+T* ~ 150 K. While the emergent negative thermal expansion below T* strongly
+supports a distinct phase at low-temperature, absence of energy gap opening,
+splitting/folding of bands, nor long-range lattice distortion are seen across
+T*. We propose that the competition between growing instability towards orbital
+ordering and its inherent geometric frustration in the Ti-pyrochlore network
+results in a new quantum state of matter with robust high entropic nature below
+T*. Our findings collectively point to a unique Fermiology in frustrated
+three-dimensional transition metal oxides, and its connection to
+superconductivity below Tc is open as an interesting future challenge. Also, a
+potential guideline is unexpectedly provided for designing zero thermal
+expansion metal to develop future solid-state devices.",2306.06708v1
+2023-06-26,The Strange Metal State of the high-Tc Cuprates,"This paper is dedicated to the memory of Professor K. Alex M\""uller. I
+present a few remarks about my interactions with Alex over the years. Then I
+present a very brief summary of recent transport studies of the strange metal
+normal-state in the high-temperature copper oxide superconductors, a subject of
+great interest to Alex.",2306.14794v1
+2023-06-29,A multiphase-field model for simulating the hydrogen-induced multi-spot corrosion on the surface of polycrystalline metals: Application to uranium metal,"Hydrogen-induced multi-spot corrosion on the surface of polycrystalline rare
+metals is a complex process, which involves the interactions between phases
+(metal, hydride and oxide), grain orientations, grain boundaries, and corrosion
+spots. To accurately simulate this process and comprehend the underlying
+physics, a theoretical method is required that includes the following
+mechanisms: i) hydrogen diffusion, ii) phase transformation, iii) elastic
+interactions between phases, especially, the interactions between the oxide
+film and the hydride, iv) elastic interactions between grains, and v)
+interactions between hydrogen solutes and grain boundaries. In this study, we
+report a multiphase-field model that incorporates all these requirements, and
+conduct a comprehensive study of hydrogen-induced spot corrosion on the uranium
+metal surface, including the investigation of the oxide film, multi-spot
+corrosion, grain orientation, and grain boundary in the monocrystal, bicrystal,
+and polycrystal systems. The results indicate that the oxide film can inhibit
+the growth of hydrides and plays a crucial role in determining the correct
+morphology of the hydride at the triple junction of phases. The elastic
+interaction between multiple corrosion spots causes the merging of corrosion
+spots and promotes the growth of hydrides. The introduction of grain
+orientations and grain boundaries results in a variety of intriguing
+intracrystalline and intergranular hydride morphologies. The model presented
+here is generally applicable to the hydrogen-induced multi-spot corrosion on
+any rare metal surface.",2306.16920v2
+2023-08-18,A mineralogical reason why all exoplanets cannot be equally oxidising,"From core to atmosphere, the oxidation states of elements in a planet shape
+its character. Oxygen fugacity (fO$_2$) is one parameter indicating these
+likely oxidation states. The ongoing search for atmospheres on rocky exoplanets
+benefits from understanding the plausible variety of their compositions, which
+depends strongly on their oxidation states -- and if derived from interior
+outgassing, on the fO$_2$ at the top of their silicate mantles. This fO$_2$
+must vary across compositionally-diverse exoplanets, but for a given planet its
+value is unconstrained insofar as it depends on how iron (the dominant
+multivalent element) is partitioned between its 2+ and 3+ oxidation states.
+Here we focus on another factor influencing how oxidising a mantle is -- a
+factor modulating fO$_2$ even at fixed Fe$^{3+}$/Fe$^{2+}$ -- the planet's
+mineralogy. Only certain minerals (e.g., pyroxenes) incorporate Fe$^{3+}$.
+Having such minerals in smaller mantle proportions concentrates Fe$^{3+}$,
+increasing fO$_2$. Mineral proportions change within planets according to
+pressure, and between planets according to bulk composition. Constrained by
+observed host star refractory abundances, we calculate a minimum fO$_2$
+variability across exoplanet mantles, of at least two orders of magnitude, due
+to mineralogy alone. This variability is enough to alter by a hundredfold the
+mixing ratio of SO$_2$ directly outgassed from these mantles. We further
+predict that planets orbiting high-Mg/Si stars are more likely to outgas
+detectable amounts of SO$_2$ and H$_2$O; and for low-Mg/Si stars, detectable
+CH$_4$, all else equal. Even absent predictions of Fe$^{3+}$ budgets, general
+insights can be obtained into how oxidising an exoplanet's mantle is.",2308.09505v1
+2023-08-30,Sub-Volt High-Speed Silicon MOSCAP Microring Modulator Driven by High Mobility Conductive Oxide,"Low driving voltage (Vpp), high-speed silicon microring modulator plays a
+critical role in energy-efficient optical interconnect and optical computing
+systems owing to its ultra-compact footprint and capability for on-chip
+wavelength-division multiplexing. However, existing silicon microring
+modulators usually require more than 2 V of Vpp, which is limited by the
+relatively weak plasma dispersion effect of silicon and the small capacitance
+density of the reversed PN-junction. Here we present a highly efficient
+metal-oxide semiconductor capacitor (MOSCAP) microring modulator through
+heterogeneous integration between silicon photonics and titanium-doped indium
+oxide, which is a high-mobility transparent conductive oxide (TCO) material
+with a strong plasma dispersion effect. The device is co-fabricated by Intel's
+photonics fab and TCO patterning processes at Oregon State University, which
+exhibits a high electro-optic modulation efficiency of 117 pm/V with a low VpiL
+of 0.12 Vcm, and consequently can be driven by an extremely low Vpp of 0.8 V.
+At a 11 GHz modulation bandwidth where the modulator is limited by the high
+parasitic capacitance, we obtained 25 Gb/s clear eye diagrams with energy
+efficiency of 53 fJ/bit and demonstrated 35 Gb/s open eyes with a higher
+driving voltage. Further optimization of the device is expected to increase the
+modulation bandwidth up to 52 GHz that can encode data at 100 Gb/s for
+next-generation, energy-efficient optical communication and computation with
+sub-volt driving voltage without using any high voltage swing amplifier.",2308.16255v1
+2023-09-20,Variability and Reliability of Graphene Field-Effect Transistors with CaF2 Insulators,"Graphene is a promising material for applications as a channel in graphene
+field-effect transistors (GFETs) which may be used as a building block for
+optoelectronics, high-frequency devices and sensors. However, these devices
+require gate insulators which ideally should form atomically flat interfaces
+with graphene and at the same time contain small densities of traps to maintain
+high device stability. Previously used amorphous oxides, such as SiO2 and
+Al2O3, however, typically suffer from oxide dangling bonds at the interface,
+high surface roughness and numerous border oxide traps. In order to address
+these challenges, here we use for the first time 2nm thick epitaxial CaF2 as a
+gate insulator in GFETs. By analyzing device-to-device variability for over 200
+devices fabricated in two batches, we find that tens of them show similar gate
+transfer characteristics. Our statistical analysis of the hysteresis up to 175C
+has revealed that while an ambient-sensitive counterclockwise hysteresis can be
+present in some devices, the dominant mechanism is thermally activated charge
+trapping by border defects in CaF2 which results in the conventional clockwise
+hysteresis. We demonstrate that both the hysteresis and bias-temperature
+instabilities in our GFETs with CaF2 are comparable to similar devices with
+SiO2 and Al2O3. In particular, we achieve a small hysteresis below 0.01 V for
+equivalent oxide thickness (EOT) of about 1 nm at the electric fields up to 15
+MV/cm and sweep times in the kilosecond range. Thus, our results demonstrate
+that crystalline CaF2 is a promising insulator for highly-stable GFETs.",2309.11233v1
+2023-09-21,Experimental and theoretical assessment of native oxide in the superconducting TaN,"In this manuscript, we show through an experimental-computational proof of
+concept the native oxide formation into superconducting TaN films. First, TaN
+was synthesized at an ultra-high vacuum system by reactive pulsed laser
+deposition and characterized in situ by X-ray photoelectron spectroscopy. The
+material was also characterized ex situ by X-ray diffraction, transmission
+electron microscopy, and the four-point probe method. It was detected that TaN
+contained considerable oxygen impurities (up to 26 %O) even though it was grown
+in an ultra-high vacuum chamber. Furthermore, the impurified TaN evidence a
+face-centered cubic crystalline structure only and exhibits superconductivity
+at 2.99 K. To understand the feasibility of the native oxide in TaN, we study
+the effect of incorporating different amounts of O atoms in TaN using ab-initio
+calculations. A thermodynamic stability analysis shows that a TaOxN1-x model
+increases its stability as oxygen is added, demonstrating that oxygen may
+always be present in TaN, even when obtained at ultra-high vacuum conditions.
+All analyzed models exhibit metallic behavior. Charge density difference maps
+reveal that N and O atoms have a higher charge density redistribution than Ta
+atoms. The electron localization function maps and line profiles indicate that
+Ta-O and Ta-N bonds are mainly ionic. As expected, stronger ionic behavior is
+observed in the Ta-O bonds due to the electronegativity difference between O
+and N atoms. Recent evidence points to superconductivity in bulk TaO,
+confirming the asseverations of superconductivity in our samples. The results
+discussed here highlight the importance of considering native oxide when
+reporting superconductivity in TaN films since the TaO regions formed in the
+compound may be key to understanding the different critical temperatures
+reported in the literature.",2309.12520v1
+2023-11-27,Electron correlation mediated site-selective charge compensation in polar/non-polar heterointerface,"One of the boundary conditions of the classical electromagnetic theory
+demands continuous electric potential across any boundary, which may not be
+naturally satisfied in atomically engineered heterostructures. Such polarity
+mismatch in oxide heterointerfaces is compensated through some
+(electronic/chemical/structural) reconstructions, leading to a myriad of
+emergent phenomena. The question we are posing is whether conventional
+semiconductor band bending framework is sufficient to comprehend compensation
+mechanisms in oxide heterostructures since, unlike semiconductors, complex
+oxides host strong electron correlations whose effects are indispensable. To
+address this, we investigate the interface between a prototypical insulating
+double perovskite Nd$_2$NiMnO$_6$ and a wide-bandgap insulator SrTiO$_3$. This
+polar/non-polar interface offers a similar scenario as the famous
+LaAlO$_3$/SrTiO$_3$ system but with an exception - two transition metal sites
+with two individual correlated energy scales. By combining several experimental
+techniques and density functional theory, we establish a site-selective charge
+compensation process that occurs explicitly at the Mn site of the film, leaving
+the Ni sites inert. This surprising selectivity, which cannot be accounted by
+existing polar compensation mechanisms, is directly attributed to the TM
+cations' relative correlation energy scales. This discovery presents that
+site-specific charge compensation can be a designers tool for tailoring
+emergent phenomena in oxide heterostructures.",2311.15726v1
+2024-01-10,Redox Poise during Rhodospirillum rubrum Phototrophic Growth Drives Large-scale Changes in Macromolecular Synthesis Pathways,"During photoheterotrophic growth on organic substrates, purple nonsulfur
+photosynthetic bacteria like Rhodospirillum rubrum can acquire electrons by
+multiple means, including oxidation of organic substrates, oxidation of
+inorganic electron donors (e.g. H$_2$), and by reverse electron flow from the
+photosynthetic electron transport chain. These electrons are stored in the form
+of reduced electron-carrying cofactors (e.g. NAD(P)H and ferredoxin). The ratio
+of oxidized to reduced redox cofactors (e.g. ratio of NAD(P)+:NAD(P)H), or
+'redox poise` is difficult to understand or predict, as are the the cellular
+processes for dissipating these reducing equivalents. Using physics-based
+models that capture mass action kinetics consistent with the thermodynamics of
+reactions and pathways, a range of redox conditions for heterophototrophic
+growth are evaluated, from conditions in which the NADP+/NADPH levels
+approached thermodynamic equilibrium to conditions in which the NADP+/NADPH
+ratio is far above the typical physiological values. Modeling results together
+with experimental measurements of macro molecule levels (DNA, RNA, proteins and
+fatty acids) indicate that the redox poise of the cell results in large-scale
+changes in the activity of biosynthetic pathways. Phototrophic growth is less
+coupled than expected to producing reductant, NAD(P)H, by reverse electron flow
+from the quinone pool. Instead, it primarily functions for ATP production
+(photophosphorylation), which drives reduction even when NADPH levels are
+relatively low compared to NADP+. The model, in agreement with experimental
+measurements of macromolecule ratios of cells growing on different carbon
+substrates, indicate that the dynamics of nucleotide versus lipid and protein
+production is likely a significant mechanism of balancing oxidation and
+reduction in the cell.",2401.04862v1
+2024-01-10,Morphological evolution and surface/interface Fe-oxide formation in epitaxial Fe(001)/MgO(001) thin film,"Epitaxial Fe film has been grown on ion beam sputtered MgO(001) substrate by
+electron beam evaporation. Reflection high energy electron diffraction (RHEED)
+and transport measurements (TM) were performed simultaneously during the growth
+of the film. While TM provided information about film morphology, RHEED
+provided information about the structure of the film.",2401.05091v1
+2024-01-18,Treatment and Aging Studies of GaAs(111)B Substrates for van der Waals Chalcogenide Film Growth,"GaAs(111)B is a semiconductor substrate widely used in research and
+commercial fields due to its low cost, mature synthesis technology, and
+excellent properties for manufacturing electronic devices. It is not only used
+to grow three-dimensional (3D) strongly-bonded materials, but has also been
+used as a substrate for layered, van der Waals (vdW)-bonded chalcogenide film
+growth. However, GaAs(111)B wafers cannot be directly used for growing
+epitaxial vdW chalcogenide films for two reasons: (1) the GaAs surface has a
+substantial number of dangling bonds that need to be passivated for vdW layers
+growth; (2) the substrate surface is covered with a thin epi-ready oxide layer
+which must be removed before film growth. In this paper, we optimize the method
+for deoxidizing GaAs(111)B substrates under a Se overpressure and successfully
+create a smooth, deoxidized, and passivated substrate for subsequent growth of
+vdW chalcogenide materials. We demonstrate the benefits of this method for the
+growth of vdW chalcogenide thin films using GaSe as a representative of vdW
+chalcogenides. In addition, we find that severely aged substrates have
+difficulty maintaining a smooth surface during the deoxidation and passivation
+process and cause GaSe crystals to nucleate in random shapes and orientations.
+We describe a method using water droplet testing to determine the age of the
+substrate. Finally, X-ray photoelectron spectroscopy (XPS) characterization
+reveals that the natural aging of GaAs(111)B in the air results in an increase
+in surface oxides, Ga2O3 and As2O3, while exposure to ultraviolet (UV)-ozone
+not only enhances the contents of these two oxides but also generates a new
+oxide, As2O5. Our research contributes to expanding the compatibility of
+GaAs(111)B with diverse growth materials and the production of high-quality
+heterostructure devices.",2401.10425v1
+2024-03-23,Bilinear magnetoresistance in 2DEG with isotropic cubic Rashba spin-orbit interaction,"Bilinear magnetoresistance has been studied theoretically in 2D systems with
+isotropic cubic form of Rashba spin-orbit interaction. We have derived the
+effective spin-orbital field due to current-induced spin polarization and
+discussed its contribution to the unidirectional system response. The analysed
+model can be applied to the semiconductor quantum wells as well as 2DEG at the
+surfaces and interfaces of perovskite oxides.",2403.15817v1
+2009-08-10,Tunnel magnetoresistance of magnetic junctions with cubic symmetry of the layers,"A tunnel magnetic junction is considered with magnetic hard and magnetic soft
+layers of cubic symmetry. The magnetic switching is analyzed of the layers by a
+magnetic field perpendicular to the initial magnetizations. In such a
+situation, an additional peak of the TMR ratio appears at the magnetic field
+value lower substantially than the anisotropy energy of the soft layer.",0908.1278v1
+2014-09-03,Photo-induced Magnetic Force Between Nanostructures,"Photo-induced magnetic force between nanostructures, at optical frequencies,
+is investigated theoretically. Till now optical magnetic effects are not used
+in scanning probe microscopy because of the vanishing natural magnetism with
+increasing frequency. On the other hand, artificial magnetism in engineered
+nanostructures led to the development of measurable optical magnetism. Here,
+two examples of nanoprobes that are able to generate strong magnetic dipolar
+fields at optical frequency are investigated: first an ideal magnetically
+polarizable nanosphere and then a circular cluster of silver nanospheres that
+has a loop-like collective plasmonic resonance equivalent to a magnetic dipole.
+Magnetic forces are evaluated based on nanostructure polarizabilities, i.e.
+induced magnetic dipoles, and magnetic-near field evaluations. As an initial
+assessment on the possibility of a magnetic nanoprobe to detect magnetic
+forces, we consider two identical magnetically polarizable nanoprobes and
+observe magnetic forces in the order of piconewtons thereby bringing it within
+detection limits of conventional atomic force microscopes at ambient pressure
+and temperature. The detection of magnetic force is a promising method in
+studying optical magnetic transitions that can be the basis of innovative
+spectroscopy applications.",1409.1188v2
+2021-03-10,Searching for Magnetic Monopoles with the Earth's Magnetic Field,"Magnetic monopoles have long been predicted in theory and could exist as a
+stable object in our universe. As they move around in galaxies, magnetic
+monopoles could be captured by astrophysical objects like stars and planets.
+Here, we provide a novel method to search for magnetic monopoles by detecting
+the monopole moment of the Earth's magnetic field. Using over six years of
+public geomagnetic field data obtained by the Swarm satellites, we apply
+Gauss's law to measure the total magnetic flux, which is proportional to the
+total magnetic charge inside the Earth. To account for the secular variation of
+satellite altitudes, we define an altitude-rescaled magnetic flux to reduce the
+dominant magnetic dipole contribution. The measured magnetic flux is consistent
+with the existing magnetic field model that does not contain a monopole moment
+term. We therefore set an upper limit on the magnetic field strength at Earth's
+surface from magnetic monopoles to be $|B_{\rm m}| < 0.13$ nT at 95% confidence
+level, which is less than $2\times 10^{-6}$ of Earth's magnetic field strength.
+This constrains the abundance of magnetically-charged objects, including
+magnetic black holes with large magnetic charges.",2103.06286v1
+2005-06-23,"Magnetic phase diagram copper metaborate CuB_2O_4 in magnetic field parallel c-axis: resonant, magnetic and magnetoelastic investigations","The magnetic phase diagram in a single crystal of copper metaborate CuB_2O_4
+in a magnetic field parallel to a tetragonal axis $c$ has been investigated.
+  From the resonant, magnetic and magnetostrictive data the phase diagram of
+CuB_2O_4 on a plane ``temperature - magnetic field'' is constructed. The
+magnetic incommensurate-commensurate phase transition is caused by the
+saturation of weak subsystem of copper ions in the strong magnetic field
+$H\|c$.",0506596v1
+2007-05-31,Geometry-induced frustration of magnetization in a planar soft-hard magnetic system,"We computationally study the frustrated magnetic configurations of a thin
+soft magnetic layer with the boundary condition fixed by underlying hard
+magnets. Driven by geometrical constraints and external magnetic field,
+transitions between frustrated energy minima result in magnetic hysteretic
+behavior. The presence of soft-magnet introduces strong undulations in the
+energy landscape in a length scale set by the magnetic property of the soft
+magnet. We propose a possible use of the phenomena to locally control the
+movement of magnetic nanoparticles.",0705.4490v1
+2014-05-19,Scaling laws of free magnetic energy stored in a solar emerging flux region,"This Letter reports scaling laws of free magnetic energy stored in a solar
+emerging flux region which is a key to understanding the energetics of solar
+active phenomena such as solar flares and coronal mass ejections. By performing
+3-dimensional magnetohydrodynamic simulations that reproduce several emerging
+flux regions of different magnetic configurations, we derive power law
+relationships among emerged magnetic flux, free magnetic energy and relative
+magnetic helicity in these emerging flux regions. Since magnetic flux is an
+observable quantity, the scaling law between magnetic flux and free magnetic
+energy may give a way to estimate invisible free magnetic energy responsible
+for solar active phenomena.",1405.4587v1
+2020-09-24,Magnetic winding: what is it and what is it good for?,"Magnetic winding is a fundamental topological quantity that underpins
+magnetic helicity and measures the entanglement of magnetic field lines. Like
+magnetic helicity, magnetic winding is also an invariant of ideal
+magnetohydrodynamics. In this article we give a detailed description of what
+magnetic winding describes, how to calculate it and how to interpret it in
+relation to helicity. We show how magnetic winding provides a clear topological
+description of magnetic fields (open or closed) and we give examples to show
+how magnetic winding and helicity can behave differently, thus revealing
+different and imporant information about the underlying magnetic field.",2009.11708v1
+2022-10-31,HTS Dipole Magnet with a Mechanical Energy Transfer in the Magnetic Field,"There were designed and successfully tested at Fermilab several high
+temperature superconducting (HTS) model magnets for particle accelerators. Some
+of them worked in a persistent current mode continuously generating magnetic
+field in the iron dominated magnet gap. In the paper was investigated a novel
+HT dipole magnet concept with a mechanical energy transfer in the magnetic
+field. To pump the energy in the superconducting HTS dipole magnet used a
+detachable magnetizer. The HTS dipole magnet was build and successfully tested
+at a liquid nitrogen temperature. Discussed the magnet design, test results,
+the proposed approach limits, and efficiency.",2211.00105v1
+2023-08-03,Magnetic interactions in IV-VI diluted magnetic semiconductors,"Diluted magnetic semiconductors (DMS) are interesting because of the
+interplay between the electronic and magnetic subsystems. We describe selected
+magnetic properties of IV-VI diluted magnetic semiconductors, looking at the
+similarities and differences between magnetic properties of II-VI, IV-VI, and
+III-V DMS. We focus on the influence of the crystalline and electronic
+structure of the material on its magnetic properties, especially on the
+exchange interactions among magnetic ions. We describe methods of determination
+of the exchange parameters by using different experimental techniques, such as
+measurements of magnetic susceptibility, magnetization, and specific heat. We
+follow the development in the material technology from bulk crystals to thin
+films and nanostructures.",2308.01780v1
+2006-05-18,Small-scale magnetic buoyancy and magnetic pumping effects in a turbulent convection,"We determine the nonlinear drift velocities of the mean magnetic field and
+nonlinear turbulent magnetic diffusion in a turbulent convection. We show that
+the nonlinear drift velocities are caused by the three kinds of the
+inhomogeneities, i.e., inhomogeneous turbulence; the nonuniform fluid density
+and the nonuniform turbulent heat flux. The inhomogeneous turbulence results in
+the well-known turbulent diamagnetic and paramagnetic velocities. The nonlinear
+drift velocities of the mean magnetic field cause the small-scale magnetic
+buoyancy and magnetic pumping effects in the turbulent convection. These
+phenomena are different from the large-scale magnetic buoyancy and magnetic
+pumping effects which are due to the effect of the mean magnetic field on the
+large-scale density stratified fluid flow. The small-scale magnetic buoyancy
+and magnetic pumping can be stronger than these large-scale effects when the
+mean magnetic field is smaller than the equipartition field. We discuss the
+small-scale magnetic buoyancy and magnetic pumping effects in the context of
+the solar and stellar turbulent convection. We demonstrate also that the
+nonlinear turbulent magnetic diffusion in the turbulent convection is
+anisotropic even for a weak mean magnetic field. In particular, it is enhanced
+in the radial direction. The magnetic fluctuations due to the small-scale
+dynamo increase the turbulent magnetic diffusion of the toroidal component of
+the mean magnetic field, while they do not affect the turbulent magnetic
+diffusion of the poloidal field.",0605444v1
+2019-09-09,Photospheric magnetic structure of coronal holes,"In this study, we investigate in detail the photospheric magnetic structure
+of 98 coronal holes using line-of-sight magnetograms of SDO/HMI, and for a
+subset of 42 coronal holes using HINODE/SOT G-band filtergrams. We divided the
+magnetic field maps into magnetic elements and quiet coronal hole regions by
+applying a threshold at $\pm 25$ G. We find that the number of magnetic bright
+points in magnetic elements is well correlated with the area of the magnetic
+elements (cc=$0.83\pm 0.01$). Further, the magnetic flux of the individual
+magnetic elements inside coronal holes is related to their area by a power law
+with an exponent of $1.261\pm 0.004$ (cc=$0.984\pm 0.001$). Relating the
+magnetic elements to the overall structure of coronal holes, we find that on
+average ($69\pm 8$) % of the overall unbalanced magnetic flux of the coronal
+holes arises from long-lived magnetic elements with lifetimes > 40 hours. About
+($22\pm 4$) % of the unbalanced magnetic flux arises from a very weak
+background magnetic field in the quiet coronal hole regions with a mean
+magnetic field density of about 0.2 to 1.2 G. This background magnetic field is
+correlated to the flux of the magnetic elements with lifetimes of > 40 h
+(cc=$0.88\pm 0.02$). The remaining flux arises from magnetic elements with
+lifetimes < 40 hours. By relating the properties of the magnetic elements to
+the overall properties of the coronal holes, we find that the unbalanced
+magnetic flux of the coronal holes is completely determined by the total area
+that the long-lived magnetic elements cover (cc=$0.994\pm 0.001$).",1909.03806v1
+1997-10-15,Near-infrared narrow-band photometry of M-giant and Mira stars: models meet observations,"From near-infrared, narrow-band photometry of 256 oxygen-rich Mira variables
+we obtain evidence about the loops that these stars follow in colour-colour
+diagrams. We also find a phase lag between indices related to molecular
+band-strength of titanium oxide and vanadium oxide. We compute colours for
+normal M-giants and Miras using hydrostatic and hydrodynamic model atmospheres
+and very extensive up-to-date line lists. Normal M-giants colours are well
+reproduced, reaching a high quantitative agreement with observations for
+spectral types earlier than M7. The out-of-phase variations of the various
+spectral features of Miras are also acceptably reproduced, despite limitations
+in the modelling. This enables us to confirm that the phase lag phenomenon
+results from the propagation of perturbations in the extended atmosphere. It
+opens new perspectives in the spectral modelling of Miras.",9710157v1
+2005-10-05,Pixie Dust: The Silicate Features in the Diffuse Interstellar Medium,"We have analyzed the 9.7 and ``18'' micron interstellar silicate absorption
+features along the line of sight toward four heavily extincted galactic WC-type
+Wolf-Rayet (WR) stars. We construct two interstellar extinction curves from
+1.25 to 25 micron using near-IR extinction measurements from the literature
+along with the silicate profiles of WR 98a (representing the local ISM) and GCS
+3 (representing the Galactic Center). We have investigated the mineralogy of
+the interstellar silicates by comparing extinction profiles for amorphous
+silicates with olivine and pyroxene stochiometry to the 9.7 and ``18'' micron
+absorption features in the WR 98a spectrum. In this analysis, we have
+considered solid and porous spheres and a continuous distribution of
+ellipsoids. While it is not possible to simultaneously provide a perfect match
+to both profiles, we find the best match requires a mixture of these two types
+of compounds. We also consider iron oxides, aluminosilicates and silicate
+carbide (SiC) as grain components. Iron oxides cannot be accommodated in the
+observed spectrum, while the amount of Si in SiC is limited to <4%. Finally, we
+discuss the cosmic elemental abundance constraints on the silicate mineralogy,
+grain shape and porosity.",0510156v1
+2006-03-21,"On the Unusual Depletions toward Sk 155, or What Are the Small Magellanic Cloud Dust Grains Made of?","The dust in the Small Magellanic Cloud (SMC), an ideal analog of primordial
+galaxies at high redshifts, differs markedly from that in the Milky Way by
+exhibiting a steeply rising far-ultraviolet extinction curve, an absence of the
+2175 Angstrom extinction feature, and a local minimum at ~12 micron in its
+infrared emission spectrum, suggesting the lack of ultrasmall carbonaceous
+grains (i.e. polycyclic aromatic hydrocarbon molecules) which are ubiquitously
+seen in the Milky Way. While current models for the SMC dust all rely heavily
+on silicates, recent observations of the SMC sightline toward Sk 155 indicated
+that Si and Mg are essentially undepleted and the depletions of Fe range from
+mild to severe, suggesting that metallic grains and/or iron oxides, instead of
+silicates, may dominate the SMC dust. However, in this Letter we apply the
+Kramers-Kronig relation to demonstrate that neither metallic grains nor iron
+oxides are capable of accounting for the observed extinction; silicates remain
+as an important contributor to the extinction, consistent with current models
+for the SMC dust.",0603573v1
+2006-06-06,Constraints on the mass of a habitable planet with water of nebular origin,"From an astrobiological point of view, special attention has been paid to the
+probability of habitable planets in extrasolar systems. The purpose of this
+study is to constrain a possible range of the mass of a terrestrial planet that
+can get water. We focus on the process of water production through oxidation of
+the atmospheric hydrogen--the nebular gas having been attracted
+gravitationally--by oxide available at the planetary surface. For the water
+production to work well on a planet, a sufficient amount of hydrogen and enough
+high temperature to melt the planetary surface are needed. We have simulated
+the structure of the atmosphere that connects with the protoplanetary nebula
+for wide ranges of heat flux, opacity, and density of the nebular gas. We have
+found both requirements are fulfilled for an Earth-mass planet for wide ranges
+of the parameters. We have also found the surface temperature of planets of <=
+0.3 Earth masses is lower than the melting temperature of silicate (~ 1500K).
+On the other hand, a planet of more than several Earth masses becomes a gas
+giant planet through runaway accretion of the nebular gas.",0606117v1
+1996-02-13,Surface Structure and Catalytic $CO$ Oxidation Oscillations,"A cellular automaton model is used to describe the dynamics of the catalytic
+oxidation of $CO$ on a $Pt(100)$ surface. The cellular automaton rules account
+for the structural phase transformations of the $Pt$ substrate, the reaction
+kinetics of the adsorbed phase and diffusion of adsorbed species. The model is
+used to explore the spatial structure that underlies the global oscillations
+observed in some parameter regimes. The spatiotemporal dynamics varies
+significantly within the oscillatory regime and depends on the harmonic or
+relaxational character of the global oscillations. Diffusion of adsorbed $CO$
+plays an important role in the synchronization of the patterns on the substrate
+and this effect is also studied.",9602015v1
+1992-09-19,Electron-Phonon Driven Spin Frustration in Multi-Band Hubbard Models: MX Chains and Oxide Superconductors,"We discuss the consequences of both electron-phonon and electron-electron
+couplings in 1D and 2D multi-band (Peierls-Hubbard) models. After briefly
+discussing various analytic limits, we focus on (Hartree-Fock and exact)
+numerical studies in the intermediate regime for both couplings, where unusual
+spin-Peierls as well as long-period, frustrated ground states are found. Doping
+into such phases or near the phase boundaries can lead to further interesting
+phenomena such as separation of spin and charge, a dopant-induced phase
+transition of the global (parent) phase, or real-space (``bipolaronic'')
+pairing. We discuss possible experimentally observable consequences of this
+rich phase diagram for halogen-bridged, transition metal, linear chain
+complexes (MX chains) in 1D and the oxide superconductors in 2D.",9209027v1
+1993-08-27,Reduction of three-band model for copper oxides to single-band generalized t~-~J model,"A three-band model for copper oxides in the region of parameters where the
+second hole on the copper has energy close to the first hole on the oxygen is
+considered. The exact solution for one hole on a ferromagnetic background of
+the ordered copper spins is obtained. A general procedure for transformation of
+the primary Hamiltonian to the Hamiltonian of singlet and triplet excitations
+is proposed. Reduction of the singlet-triplet Hamiltonian to the single-band
+Hamiltonian of the generalized t~-~J model is performed. A comparison of the
+solution for the generalized t~-~J model on a ferromagnetic background with the
+exact solution shows a very good agreement.",9308034v1
+1995-07-27,Intercalation and Staging Behavior in Super-Oxygenated $La_2CuO_{4 + δ}$,"A high temperature electrochemical oxidation process has been used to produce
+large single crystals of $La_2CuO_{4 + \delta}$ suitable for neutron scattering
+experiments. Below room temperature the oxygen-rich phases have structural
+superlattice scattering peaks which indicate new periodicities ranging from 2
+to 6.6 layers perpendicular to the copper oxide planes. A model structure
+originally proposed for $La_2NiO_{4 + \delta}$ can account for the superlattice
+peaks as a result of anti-phase domain boundaries between different tilt
+directions of the CuO$_6$ octahedra. Within this model, the changes in CuO$_6$
+tilt directions are induced by segregated layers of interstitial oxygen which
+order in a manner similar to intercalants in graphite. This structural model
+thus clarifies previous work and establishes $La_2CuO_{4 + \delta}$ as a unique
+lamellar superconducting system with annealed disorder.",9507124v1
+1995-10-02,A new approach for perovskites in large dimensions,"Using the Hubbard Hamiltonian for transition metal-3d and oxygen-2p states
+with perovskite geometry, we propose a new scaling procedure for a nontrivial
+extension of these systems to large spatial dimensions $D$. The scaling
+procedure is based on a selective treatment of different hopping processes for
+large $D$ and can not be generated by a unique scaling of the hopping element.
+The model is solved in the limit $D \rightarrow \infty$ by the iterated
+perturbation theory and using an extended non-crossing approximation. We
+discuss the evolution of quasi particles at the Fermi-level upon doping,
+leading to interesting insight into the dynamical character of the charge
+carriers near the metal insulator instability of transition metal oxide
+systems, three dimensional perovskites and other strongly correlated transition
+metal oxides.",9510003v1
+1996-02-06,Renormalization Group Approach to the Normal State of Copper-Oxide Superconductors,"We study by means of renormalization group techniques the effect that on the
+two-dimensional electron liquid may have the van Hove singularities observed
+experimentally in the copper-oxide superconductors. We find significant
+deviations from Fermi liquid behavior, that lead to the appearance of an
+unstable fixed point in the renormalization group flow of the effective
+coupling constant. Besides the attenuation of electron quasiparticles already
+known on phenomenological grounds, our approach is able to explain the
+reduction in the dispersion of the band as well as the pinning of the Fermi
+level near the singularity, as observed in the photoemission experiments.",9602033v1
+1996-04-17,Dynamical Mean Field Theory for Perovskites,"Using the Hubbard Hamiltonian for transition metal-3d and oxygen-2p states
+with perovskite geometry, we present a dynamical mean field theory which
+becomes exactin the limit of large coordination numbers or equivalently large
+spatial dimensions $D$. The theory is based on a new description of these
+systems for large $D$ using a selective treatment of different hopping
+processes which can not be generated by a unique scaling of the hopping
+element. The model is solved using a perturbational approach and an extended
+non-crossing approximation. We discuss the breakdown of the perturbation theory
+near half filling, the origin of the various 3d and 2p bands, the doping
+dependence of its spectral weight, and the evolution of quasi particles at the
+Fermi-level upon doping, leading to interesting insight into the dynamical
+character of the charge carriers near the metal insulator instability of
+transition metal oxide systems, three dimensional perovskites and other
+strongly correlated transition metal oxides.",9604108v2
+1996-05-31,d-wave superconductivity near charge instabilities,"We investigate the symmetry of the superconducting order parameter in the
+proximity of a phase-separation or of an incommensurate charge-density-wave
+instability. The attractive effective interaction at small or intermediate
+transferred momenta is singular near the instability. This strongly
+$q$-dependent interaction, together with a residual local repulsion between the
+quasiparticles and an enhanced density of states for band structures
+appropriate for the high temperature superconducting oxides, strongly favors
+the formation of $d$-wave superconductivity. The relative stability with
+respect to superconductivity in the $s$-wave channel is discussed in detail,
+finding this latter hardly realized in the above conditions. The
+superconducting temperature is mostly determined by the closeness to the
+quantum critical point associated to the charge instability and displays a
+stronger dependence on doping with respect to the simple proximity to a Van
+Hove singularity. The relevance of this scenario and the generic agreement of
+the resulting phase diagram with the properties displayed by high temperature
+superconducting oxides is discussed.",9605193v1
+1996-06-22,Orbital Liquid in Perovskite Transition-Metal Oxides,"We study the effects of the degeneracy of the $e_g$ orbitals as well as the
+double exchange interaction with $t_{2g}$ spins in perovskite transition-metal
+oxides. In addition to the spin field ${\vec S}_i$, the isospin field ${\vec
+T}_i$ is introduced to describe the orbital degrees of freedom. The isospin is
+the quantum dynamical variable, and is represented by the boson with a
+constraint. The dispersion of this boson is flat along $(\pi/a,\pi/a,k_z)$
+($a$: lattice constant) and the other two equivalent directions. This enables
+the orbital disordered phase down to low temperatures. We interpret some of the
+anomalous experiments, i.e., optical absorption and d.c. resistivity, in the
+low temperature ferromagnetic phase of La$_{1-x}$Sr$_x$MnO$_3$ with $x > 0.2$
+in terms of this orbital liquid picture.",9606160v1
+1996-11-12,Estimates of electronic interaction parameters for La$M$O$_3$ compounds ($M$=Ti-Ni) from ab-initio approaches,"We have analyzed the ab-initio local density approximation band structure
+calculations for the family of perovskite oxides, La$M$O$_3$ with $M$=Ti-Ni
+within a parametrized nearest neighbor tight-binding model and extracted
+various interaction strengths. We study the systematics in these interaction
+parameters across the transition metal series and discuss the relevance of
+these in a many-body description of these oxides. The results obtained here
+compare well with estimates of these parameters obtained via analysis of
+electron spectroscopic results in conjunction with the Anderson impurity model.
+The dependence of the hopping interaction strength, t, is found to be
+approximately $r^{-3}$.",9611098v1
+1996-11-27,Study of CO Oxidation over Ru(0001) at High Gas Pressures,"Experiments performed at high gas partial pressures have demonstrated that
+the kinetics of the CO oxidation reaction at Ru(0001) is different and somewhat
+anomalous compared to that over other transition metal surfaces and, in
+particular, the turnover rate is exceptionally high. In order to gain insight
+into the underlying reasons for this behavior, we performed density functional
+theory calculations using the generalized gradient approximation for the
+exchange-correlation functional. We find that the high rate is due to a weakly,
+but nevertheless well bound, (1x1) oxygen adsorbate layer which may form for
+high O_2 pressures but not under usual ultra high vacuum conditions. The
+calculations indicate that reaction to CO_2 occurs both via scattering of
+gas-phase CO molecules as well as by CO molecules weakly adsorbed at vacancies
+in the oxygen adlayer, where the latter mechanism dominates the rate.",9611217v1
+1996-11-27,Mechanism of efficient carbon monoxide oxidation at Ru(0001),"We performed density-functional theory calculations using the generalized
+gradient approximation for the exhange-correlation functional to investigate
+the unusual catalytic behavior of Ru under elevated gas pressure conditions for
+the carbon monoxide oxidation reaction, which includes a particularly high CO_2
+turnover. Our calculations indicate that a full monolayer of adsorbed oxygen
+actuates the high rate, enabling CO_2 formation via both scattering of
+gas-phase CO molecules as well as by CO molecules adsorbed at oxygen vacancies
+in the adlayer, where the latter mechanism is expected to be very efficient due
+to the relatively weak adsorption energy of both CO and O, as well as the close
+proximity of these reactants. In the present paper we analyse the bonding and
+electronic properties associated with the reaction pathway for CO_2 production
+via the scattering reaction. We find that the identified ``bent'' transition
+state is due to electron transfer into the unoccupied 2 pi orbitals of the CO
+molecule which reduces the Pauli repulsion between the impinging CO and the
+O-covered surface. Bond formation to CO_2 then proceeds by electron transfer
+back from the CO 2 pi orbitals into the bonding region between CO and the
+adsorbed O atom.",9611220v1
+1997-05-09,Small-q electron-phonon scattering and linear dc resistivity in high-T_c oxides,"We examine the effect on the DC resistivity of small-q electron-phonon
+scattering, in a system with the electronic topology of the high-T_c oxides.
+Despite the fact that the scattering is dominantly forward, its contribution to
+the transport can be significant due to ``ondulations'' of the bands in the
+flat region and to the umpklapp process. When the extended van-Hove
+singularities are sufficiently close to $E_F$ the acoustic branch of the
+phonons contribute significantly to the transport. In that case one can obtain
+linear $T$ dependent resistivity down to temperatures as low as 10 K, even if
+electrons are scattered also by optical phonons of about 500 K as reported by
+Raman measurements.",9705085v1
+1998-03-14,Striped phases in the two-dimensional Hubbard model with long-range Coulomb interaction,"We investigate the formation of partially filled domain walls in the
+two-dimensional Hubbard model in the presence of long-range interaction. Using
+an unrestricted Gutzwiller variational approach we show that: i) the strong
+local interaction favors charge segregation in stripe domain walls; ii) The
+long-range interaction favors the formation of half-filled vertical stripes
+with a period doubling due to the charge and a period quadrupling due to the
+spins along the wall. Our results show that, besides the underlying lattice
+structure, also the electronic interactions can contribute to determine the
+different domain wall textures in Nd doped copper oxides and nickel oxides.",9803184v1
+1998-05-27,Charge ordering and long-range interactions in layered transition metal oxides,"We study the competition between long-range and short-range interactions
+among holes within the spin density wave picture of layered transition metal
+oxides. We focus on the problem of charge ordering and the charge phase
+diagram. We show that the main interactions are the long-range Coulomb
+interaction and a dipolar short-range interaction generated by the short-range
+antiferromagnetic fluctuations. We find four different phases depending on the
+strength of the dipolar interaction and the density of holes: Wigner crystal,
+diagonal stripes, horizontal-vertical stripes (loops) and a glassy-clumped
+phase. We discuss the effect of temperature, disorder and lattice effects on
+these phases.",9805367v1
+1998-09-23,Transport Properties of the One Dimensional Ferromagnetic Kondo Lattice Model : A Qualitative Approach to Oxide Manganites,"The transport properties of the ferromagnetic Kondo lattice model in one
+dimension are studied via bosonization methods. The antiferromagnetic
+fluctuations, which normally appear because of the RKKY interactions, are
+explicitly taken into account as a direct exchange between the ``core'' spins.
+It is shown that in the paramagnetic regime with the local antiferromagnetic
+fluctuations, the resistivity decays exponentially as the temperature increases
+while in the ferromagnetic regime the system is an almost perfect conductor. %A
+non-perturbative description of localized spin polarons %in the paramagnetic
+region is obtained.
+  The effect of a weak applied field is discussed to be reduced to the case of
+the ferromagnetic state leading to band splitting. The qualitative relevance of
+the results for the problem of the Oxide Manganites is emphasized.",9809309v1
+1998-10-21,Ferromagnetic ground state of an orbital degenerate electronic model for transition-metal oxides: exact solution and physical mechanism,"We present an exact ground state solution of a one-dimensional electronic
+model for transition-metal oxides in the strong coupling limit. The model
+contains doubly degenerated orbit for itinerant electrons and the Hund coupling
+between the itinerant electrons and localized spins. The ground state is proven
+to be a full ferromagnet for any density of electrons. Our model provides a
+rigorous example for metallic ferromagnetism in narrow band systems. The
+physical mechanism for ferromagnetism and its relevance to high-dimensional
+systems, like R$_{1-x}$X$_x$MnO$_3$, are discussed. Due to the orbital
+degeneracy of itinerant electrons, the superexchange coupling can be
+ferromagnetic rather than antiferromagnetic in the one-band case.",9810268v1
+1998-11-26,Kinetics of electric field induced oxygen ion migration in epitaxial metallic oxide films,"In this paper we report the observation of curent induced change of
+resistance of thin metallic oxide films. The resistance changes at a very low
+current (current density $J \geq 10^{3}$ A/cm$^{2}$). We find that the time
+dependence associated with the processes (increase of resistance) show a
+streched exponential type dependence at lower temperature, which crosses over
+to a creep type behavior at $T \geq$ 350 K. The time scale associated shows a
+drastic drop in the magnitude at $T \approx$ 350 K, where a long range
+diffusion sets in increasing the conductivity noise. The phenomena is like a
+""glass-transition"" in the random lattice of oxygen ions.",9811377v1
+1999-01-08,The Phase Separation Scenario for Manganese Oxides,"Recent computational studies of models for manganese oxides have revealed a
+rich phase diagram, not anticipated in early calculations in this context
+performed in the 1950's and 60's. In particular, the transition between the
+antiferromagnetic insulator state of the hole-undoped limit and the
+ferromagnetic metal at finite hole-density was found to occur through a
+mixed-phase process. When extended Coulomb interactions are included, a
+microscopically charge inhomogeneous state should be stabilized. These phase
+separation tendencies, also present at low electronic densities, influence the
+properties of the ferromagnetic region by increasing charge fluctuations.
+Experimental data reviewed here using several techniques for manganites and
+other materials are consistent with this scenario. Similarities with results
+previously discussed in the context of cuprates are clear from this analysis,
+although the phase segregation tendencies in manganites seem stronger.",9901057v2
+1999-02-10,Threshold electronic structure at the oxygen K edge of 3d transition metal oxides: a configuration interaction approach,"It has been generally accepted that the threshold structure observed in the
+oxygen K edge X-ray absorption spectrum in 3d transition metal oxides
+represents the electronic structure of the 3d transition metal. There is,
+however, no consensus about the correct description. We present an
+interpretation, which includes both ground state hybridization and electron
+correlation. It is based on a configuration interaction cluster calculation
+using a MO6 cluster. The oxygen K edge spectrum is calculated by annihilating a
+ligand hole in the ground state and is compared to calculations representing
+inverse photoemission experiments in which a 3d transition metal electron is
+added. Clear differences are observed related to the amount of ligand hole
+created in the ground state. Two ""rules"" connected to this are discussed.
+Comparison with experimental data of some early transition metal compounds is
+made and shows that this simple cluster approach explains the experimental
+features quite well.",9902132v2
+1999-03-29,Structure and energetics of the Si-SiO_2 interface,"Silicon has long been synonymous with semiconductor technology. This unique
+role is due largely to the remarkable properties of the Si-SiO_2 interface,
+especially the (001)-oriented interface used in most devices. Although Si is
+crystalline and the oxide is amorphous, the interface is essentially perfect,
+with an extremely low density of dangling bonds or other electrically active
+defects. With the continual decrease of device size, the nanoscale structure of
+the silicon/oxide interface becomes more and more important. Yet despite its
+essential role, the atomic structure of this interface is still unclear. Using
+a novel Monte Carlo approach, we identify low-energy structures for the
+interface. The optimal structure found consists of Si-O-Si ""bridges"" ordered in
+a stripe pattern, with very low energy. This structure explains several
+puzzling experimental observations.",9903424v1
+1999-05-19,Effects of Orbital Degeneracy and Electron Correlation on Charge Dynamics in Perovskite Manganese Oxides,"Taking the orbital degeneracy of $e_g$ conduction bands and the Coulomb
+interaction into account in a double-exchange model, we investigate charge
+dynamics of perovskite Mn oxides by the Lancz$\ddot{\rm o}$s diagonalization
+method. In the metallic phase near the Mott insulator, it is found that the
+optical conductivity for a spin-polarized two-dimensional system exhibits a
+weight transfer to a broad and incoherent structure within the lower-Hubbard
+band together with a suppressed Drude weight. It reproduces qualitative feature
+of the experimental results. As an orbital effect, we find that an anomalous
+charge correlation at quarter filling suppresses the coherent charge dynamics
+and signals precursor to the charge ordering.",9905271v1
+1999-06-17,Anomalous c-axis charge dynamics in copper oxide materials,"Within the t-J model, the c-axis charge dynamics of the copper oxide
+materials in the underdoped and optimally doped regimes is studied by
+considering the incoherent interlayer hopping. It is shown that the c-axis
+charge dynamics is mainly governed by the scattering from the in-plane
+fluctuation. In the optimally doped regime, the c-axis resistivity is a linear
+in temperatures, and shows the metallic-like behavior for all temperatures,
+while the c-axis resistivity in the underdoped regime is characterized by a
+crossover from the high temperature metallic-like behavior to the low
+temperature semiconducting-like behavior, which are consistent with experiments
+and numerical simulations.",9906260v2
+1999-09-23,In-plane gate single-electron transistor in Ga[Al]As fabricated by scanning probe lithography,"A single-electron transistor has been realized in a Ga[Al]As heterostructure
+by oxidizing lines in the GaAs cap layer with an atomic force microscope. The
+oxide lines define the boundaries of the quantum dot, the in-plane gate
+electrodes, and the contacts of the dot to source and drain. Both the number of
+electrons in the dot as well as its coupling to the leads can be tuned with an
+additional, homogeneous top gate electrode. Pronounced Coulomb blockade
+oscillations are observed as a function of voltages applied to different gates.
+We find that, for positive top-gate voltages, the lithographic pattern is
+transferred with high accuracy to the electron gas. Furthermore, the dot shape
+does not change significantly when in-plane voltages are tuned.",9909340v1
+1999-10-17,Shrinking limits of silicon MOSFET's: Numerical study of 10-nm-scale devices,"We have performed numerical modeling of dual-gate ballistic n-MOSFET's with
+channel length of the order of 10 nm, including the effects of quantum
+tunneling along the channel and through the gate oxide. Our analysis includes a
+self-consistent solution of the full (two-dimensional) electrostatic problem,
+with account of electric field penetration into the heavily-doped electrodes.
+The results show that transistors with channel length as small as 8 nm can
+exhibit either a transconductance up to 4,000 mS/mm or gate modulation of
+current by more than 8 orders of magnitude, depending on the gate oxide
+thickness. These characteristics make the devices satisfactory for logic and
+memory applications, respectively, though their gate threshold voltage is
+rather sensitive to nanometer-scale variations in the channel length.",9910258v1
+1999-10-22,Pseudogap due to antiferromagnetic fluctuations and the phase diagram of the high temperature oxide superconductors,"A reduction of the density of states near the Fermi energy in the normal
+state (pseudogap) of high-temperature oxide superconductors is examined on the
+basis of the two-dimensional tight-binding model with effective interactions
+due to antiferromagnetic fluctuations. By using antiferromagnetic correlation
+lengths which are phenomenologically assumed, the doping dependence of the
+pseudogap is obtained. The superconducting transition temperature decreases and
+eventually vanishes due to the pseudogap as the hole concentration is reduced.",9910349v4
+2000-03-16,EXAFS indication of double-well potential for oxygen vibration in Ba_{1-x}K_xBiO_3,"X-ray absorption spectra of oxide systems Ba_{1-x}K_xBiO_3 and BaPbO_3 above
+Bi- and Pb-L3 absorption edges were investigated. It was shown that oxygen ions
+move in double-well potential and their oscillations are correlated with charge
+carrier movement. Observed breathing-like oxygen vibration in double-well
+potential with large amplitude and low frequency causes the strong
+electron-phonon coupling and high Tc values in doped BaBiO_3. Based on the
+experimental data, the model of relationship of electronic and local crystal
+structures is proposed that is in a good agreement with the results of
+transport measurements, inelastic neutron and electron scattering, Raman
+scattering, and photoemission spectroscopy. In the framework of the model the
+possible reasons of superconductivity in perovskite-like oxides are discussed.",0003279v1
+2000-04-14,Incoherent Charge Dynamics in Perovskite Manganese Oxides,"A minimal model is proposed for the perovskite manganese oxides showing the
+strongly incoherent charge dynamics with a suppressed Drude weight in the
+ferromagnetic and metallic phase near the insulator. We investigate a
+generalized double-exchange model including three elements; the orbital
+degeneracy of $e_g$ conduction bands, the Coulomb interaction and fluctuating
+Jahn-Teller distortions. We demonstrate that Lancz$\ddot{\rm o}$s
+diagonalization calculations combined with Monte Carlo sampling of the largely
+fluctuating lattice distortions result in the optical conductivity which
+quantitatively accounts for the experimental indications. It is found that all
+the three elements are indispensable to understand the charge dynamics in these
+compounds.",0004232v1
+2000-04-17,Ferromagnetism and phase separation in one-dimensional d-p and periodic Anderson models,"Using the Density Matrix Renormalization Group, we study metallic
+ferromagnetism in a one-dimensional copper-oxide model which contains one
+oxygen p-orbital and one copper d-orbital. The parameters for the d-p model can
+be chosen so that it is similar to the one-dimensional periodic Anderson model.
+For these parameters, we compare the ground-state phase diagram with that of
+the Anderson model and find a ferromagnetic region analogous to one found in
+the Anderson model, but which is pushed to somewhat higher densities and
+interaction strengths. In both models, we find a region within the
+ferromagnetic phase in which phase separation between a localized ferromagnetic
+domain and a weakly antiferromagnetic regime occurs. We then choose a set of
+parameter values appropriate for copper-oxide materials and explore the
+ground-state phase diagram as a function of the oxygen-oxygen hopping strength
+and the electron density. We find three disconnected regions of metallic
+ferromagnetism and give physical pictures of the three different mechanisms for
+ferromagnetism in these phases.",0004265v1
+2000-11-22,Surface melting of methane and methane film on magnesium oxide,"Experiments on surface melting of several organic materials have shown
+contradictory results. We study the Van der Waals interactions between
+interfaces in surface melting of the bulk CH_4 and interfacial melting of the
+CH_4 film on the MgO substrate. This analysis is based on the theory of
+Dzyaloshinskii, Lifshitz, and Pitaevskii for dispersion forces in materials
+characterized by the frequency dependent dielectric functions. These functions
+for magnesium oxide and methane are obtained from optical data using an
+oscillator model of the dielectric response. The results show that a repulsive
+interaction between the solid-liquid and liquid-vapor interfaces exists for the
+bulk methane. We also found that the van der Waals forces between two
+solid-liquid interfaces are attractive for the CH_4 film on the MgO substrate.
+This implies that the van der Waals forces induce the presence of complete
+surface melting for the bulk methane and the absence of interfacial melting for
+CH_4 on the MgO substrate.",0011377v1
+2000-11-25,Memory Effect in Silicon Nitride in Silicon Devices,"The dominant dielectric used currently in silicon devices is silicon oxide.
+Its application for future devices will be impeded by several fundamental
+limitations which lead to low reliability of semiconductor devices and to the
+necessity of alternative dielectrics. Amorphous silicon nitride and oxynitride
+are considered now as alternative to silicon oxide in future devices. One of
+the unique property of amorphous silicon nitride is the electron and hole
+capture by the deep traps with extremely long life time (10 years) in the
+captured state (the memory effect). This property is employed in memory devices
+and microprocessors in computers. Despite numerous efforts the nature of traps
+responsible for the memory effect in this material is so far unclear. In this
+paper we discuss the nature of such traps using the quantum-chemical
+simulation. The calculations show that the defects responsible for the electron
+and hole capture in amorphous silicon nitride can be the Si-Si defects created
+by excess silicon atoms.",0011435v1
+2000-11-25,Evidence for novel polaronic Fermi-liquid in doped oxides,"The modern multi-polaron theory predicts a polaronic Fermi-liquid state, but
+such a state has not been unambigously confirmed by experiment so far. Here we
+report theoretical and experimental studies of the isotope effects on the low
+temperature kinetic properties of the doped ferromagnetic manganites. Our
+results provide clear evidence for a novel polaronic Fermi-liquid state in
+doped oxides.",0011436v2
+2001-02-20,Spinwaves and large electron-phonon coupling near the metal-insulator transition in hole-doped high-T$_C$ oxides,"A theory for spin and lattice couplings to the electronic states in
+high-T$_C$ oxides is presented, with HgBa$_2$CuO$_4$ as an example. A simple
+analytical model suggests that the barrel band is sensitive to potential
+perturbations with long-range Fourier components, and that gaps can be opened
+at the Fermi energy. This is confirmed in self-consistent band calculations for
+modulations in elongated supercells, where spin waves and phonon coupling
+compete for equal q-vectors. It is argued that the wavelengths of spin-wave
+modulations and of the phonon modes with large coupling, depend on the doping.
+This mechanism supports the idea that pseudogaps are caused by stripe like
+spin-modulations in underdoped systems, while superconductivity is attributed
+to enhanced electron-phonon coupling for long wavelength phonons.",0102343v1
+2001-03-08,Superconducting thin films of MgB2 on (001)-Si by pulsed laser deposition,"Superconducting thin films have been prepared on Si-substrates, using pulsed
+laser deposition from a target composed of a mixture of Mg and MgB2 powders.
+The films were deposited at room temperature and post-annealed at 600 degrees
+C. The zero resistance transition temperatures were 12 K, with an onset
+transition temperature of 27 K. Special care has been taken to avoid oxidation
+of Mg in the laser plasma and deposited film, by optimizing the background
+pressure of Ar gas in the deposition chamber. For this the optical emission in
+the visible range from the plasma has been used as indicator. Preventing Mg
+from oxidation was found to be essential to obtain superconducting films.",0103198v1
+2001-03-28,Soft x-ray spectroscopy measurements of the p-like density of states of B in MgB2 and evidence for surface boron oxides on exposed surfaces,"Soft X-ray absorption and fluorescence measurements are reported for the
+K-edge of B in MgB2. The measurements confirm a high density of B
+pxy(sigma)-states at the Fermi edge and extending to approximately 0.9 eV above
+the edge. A strong resonance is observed in elastic scattering through a
+core-exciton derived from out-of-plane pz(pi*)-states. Another strong
+resonance, observed in both elastic and inelastic spectra, is identified as a
+product of surface boron oxides.",0103593v1
+2001-04-09,A continuous compositional-spread technique based on pulsed-laser deposition and applied to the growth of epitaxial films,"A novel continuous-compositional spread technique based on the non-uniformity
+of the deposition rate typically observed in Pulsed Laser Deposition (PLD) is
+introduced. The approach uses the spatial variations in the deposition-rate
+naturally occurring in PLD; therefore, there is no need for the masks typically
+used in combinatorial techniques. Consequently, combinatorial materials
+synthesis can be carried out under optimized film growth conditions (e.g. at
+high temperature). Additionally, lifting the need for post-annealing renders
+this method applicable to heat-sensitive materials and substrates (e.g. films
+of transparent oxides on polymer substrates). Composition determination across
+the sample and mapping of physical properties onto the ternary phase diagram is
+achieved via a simple algorithm using the parameters that describe the
+deposition-rate profiles. Results are shown for the high-temperature growth of
+crystalline perovskites (including (Ba,Sr)TiO3 and the formation of a
+metastable alloy between SrRuO3 and SrSnO3) and the room-temperature growth of
+transparent conducting oxides.",0104157v1
+2001-04-17,Surface Core-Level Shifts at an oxygen-rich Ru Surface: O/Ru(0001) vs. RuO_2(110),"We present density-functional theory calculations of Ru 3d and O 1s surface
+core-level shifts (SCLSs) at an oxygen-rich Ru(0001) surface, namely for the
+O(1x1)/Ru(0001) chemisorption phase and for two surface terminations of fully
+oxidized RuO_2(110). Including final-state effects, the computed SCLSs can be
+employed for the analysis of experimental X-ray photoelectron spectroscopy
+(XPS) data enabling a detailed study of the oxidation behaviour of the Ru(0001)
+surface. We show that certain peaks can be used as a fingerprint for the
+existence of the various phases and propose that the long disputed satellite
+peak in RuO_2(110) XPS data originates from a hitherto unaccounted surface
+termination.",0104306v2
+2001-06-29,Fermi Surface Nesting and Nanoscale Fluctuating Charge/Orbital Ordering in Colossal Magnetoresistive Oxides,"We used high resolution angle-resolved photoemission spectroscopy to reveal
+the Fermi surface and key transport parameters of the metallic state of the
+layered Colossal Magnetoresistive (CMR) oxide La1.2Sr1.8Mn2O7. With these
+parameters the calculated in-plane conductivity is nearly one order of
+magnitude larger than the measured DC conductivity. This discrepancy can be
+accounted for by including the pseudogap which removes at least 90% of the
+spectral weight at the Fermi energy. Key to the pseudogap and many other
+properties are the parallel straight Fermi surface sections which are highly
+susceptible to nesting instabilities. These nesting instabilities produce
+nanoscale fluctuating charge/orbital modulations which cooperate with
+Jahn-Teller distortions and compete with the electron itinerancy favored by
+double exchange.",0106655v1
+2001-07-11,"Composition, structure and stability of RuO_2(110) as a function of oxygen pressure","Using density-functional theory (DFT) we calculate the Gibbs free energy to
+determine the lowest-energy structure of a RuO_2(110) surface in thermodynamic
+equilibrium with an oxygen-rich environment. The traditionally assumed
+stoichiometric termination is only found to be favorable at low oxygen chemical
+potentials, i.e. low pressures and/or high temperatures. At realistic O
+pressure, the surface is predicted to contain additional terminal O atoms.
+Although this O excess defines a so-called polar surface, we show that the
+prevalent ionic model, that dismisses such terminations on electrostatic
+grounds, is of little validity for RuO_2(110). Together with analogous results
+obtained previously at the (0001) surface of corundum-structured oxides, these
+findings on (110) rutile indicate that the stability of non-stoichiometric
+terminations is a more general phenomenon on transition metal oxide surfaces.",0107229v1
+2001-10-22,A Novel Theory for High Temperature Superconductors considering Inhomogeneous Charge Distributions,"We present a percolation theory for the high-$T_c$ oxides pseudogap and $T_c$
+dependence on the hole level. The doping dependent inhomogeneous charge
+structure is modeled by a distribution which may represent the stripe
+morphology and yield a spatial distribution of local $T_c(r)$. The temperature
+onset of spatial dependent superconducting gap is identified with the vanishing
+of the pseudogap temperature $T^*$. The transition to a superconducting state
+corresponds to the percolation threshold among regions of different $T_c$. As a
+paradigm we use a Hubbard Hamiltonian with a mean field approximation to yield
+a doping and temperature dependent superconducting d-wave gap. We show here
+that this new approach reproduces the phase diagram, explains and gives new
+insights on several experimental features of high-$T_c$ oxides.",0110479v1
+2001-11-20,High-pressure study on the superconducting pyrochlore oxide Cd2Re2O7,"Superconducting and structural phase transitions in a pyrochlore oxide
+Cd2Re2O7 are studied under high pressure by x-ray diffraction and electrical
+resistivity measurements. A rich P-T phase diagram is obtained, which contains
+at least two phases with the ideal and slightly distorted pyrochlore
+structures. It is found that the transition between them is suppressed with
+increasing pressure and finally disappears at a critical pressure Pc = 3.5 GPa.
+Remarkable enhancements in the residual resistivity as well as the coefficient
+A of the AT 2 term in the resistivity are found around the critical pressure.
+Superconductivity is detected only for the phase with the structural
+distortion. It is suggested that the charge fluctuations of Re ions play a
+crucial role in determining the electronic properties of Cd2Re2O7.",0111388v2
+2002-01-09,A Quantum-Dot Array as Model for Copper-Oxide Superconductors: A Dedicated Quantum Simulator for the Many-Fermion Problem,"Quantum systems with a large number of fermionic degrees of freedom are
+intractable by quantum simulations. In this paper we introduce the concept of a
+dedicated quantum simulator(DQS) which is an artificial system of quantum dots
+whose Hamiltonian maps exactly to the original many fermion problem. While the
+universal quantum simulator (UQS) introduced by Feynman in 1982 can simulate
+any quantum mechanical many-body problem, a DQS can only solve a particular
+many body problem. Our concept of the dedicated quantum simulator is not a
+quantum computer but rather a quantum ""analog"" device, dedicated to a
+particular quantum computation. As an example, we consider the system of the
+$CuO$ plane in the copper-oxide superconductors and we propose an array of
+electrostatically confined quantum dots to be used as its dedicated quantum
+simulator. We show that this dedicated device can be used to image stripe
+formation as a function of the electron doping using electric force microscopy.
+We argue that such a dedicated quantum simulator may be easier to realize in
+the future compared to a general purpose quantum computer.",0201142v1
+2002-01-29,Three-dimensional flux states as a model for the pseudogap phase of transition metal oxides,"We propose that the pseudogap state observed in the transition metal oxides
+can be explained by a three-dimensional flux state, which exhibits
+spontaneously generated currents in its ground state due to electron-electron
+correlations. We compare the energy of the flux state to other classes of mean
+field states, and find that it is stabilized over a wide range of $t$ and
+$\delta$. The signature of the state will be peaks in the neutron diffraction
+spectra, the location and intensity of which are presented. The dependence of
+the pseudogap in the optical conductivity is calculated based on the parameters
+in the model.",0201524v1
+2002-04-11,In-plane Anisotropy on Resistivity and Thermopower in The Misfit Layered Oxide Bi2-xPbxSr2Co2Oy,"We investigated the in-plane anisotropy on the resistivity and thermopower of
+Bi2-xPbxSr2Co2Oy single crystals, which have a misfit structure between the
+hexagonal CoO2 layer and the rock salt Bi2Sr2O4 layer. The resistivity and
+thermopower show significantly large anisotropy, which exceeds two at maximum.
+This anisotropy would come from the anisotropic pseudogap formation enhanced by
+the misfit structure. The thermopower changes with Pb doping to take a maximum
+at x=0.4. The misfit structure improves the thermoelectric properties through
+chemical pressure. The power factor is as large as 9 muW/cmK2 at 100 K for
+x=0.6, which is the highest value for thermoelectric oxides at 100 K.",0204245v1
+2002-08-07,Size and Location Control of Si Nanocrystals at Ion Beam Synthesis in Thin SiO2 Films,"Binary collision simulations of high-fluence 1 keV Si ion implantation into 8
+nm thick SiO2 films on (001)Si were combined with kinetic Monte Carlo
+simulations of Si nanocrystal (NC) formation by phase separation during
+annealing. For nonvolatile memory applications, these simulations help to
+control size and location of NCs. For low concentrations of implanted Si, NCs
+form via nucleation, growth and Ostwald ripening, whereas for high
+concentrations Si separates by spinodal decomposition. In both regimes, NCs
+form above a thin NC free oxide layer at the SiO2/Si interface. This,
+self-adjusted layer has just a thickness appropriate for NC charging by direct
+electron tunneling. Only in the nucleation regime the width of the tunneling
+oxide and the mean NC diameter remain constant during a long annealing period.
+This behavior originates from the competition of Ostwald ripening and Si loss
+to the Si/SiO2 interface. The process simulations predict that, for nonvolatile
+memories, the technological demands on NC synthesis are fulfilled best in the
+nucleation regime.",0208137v1
+2002-10-04,Steps on current-voltage characteristics of a silicon quantum dot covered by natural oxide,"Considering a double-barrier structure formed by a silicon quantum dot
+covered by natural oxide with two metallic terminals, we derive simple
+conditions for a step-like voltage-current curve. Due to standard chemical
+properties, doping phosphorus atoms located in a certain domain of the dot form
+geometrically parallel current channels. The height of the current step
+typically equals to (1.2 pA)N, where N=0,1,2,3... is the number of doping atoms
+inside the domain, and only negligibly depends on the actual position of the
+dopants. The found conditions are feasible in experimentally available
+structures.",0210104v2
+2002-10-17,Phase evolution of layered cobalt oxides versus varying corrugation of the cobalt-oxygen basal plane,"A general spin-state model and a qualitative physical picture have been
+proposed for a class of lately synthesized layered cobalt oxides (LCOs) by
+means of density functional calculations. As the plane corrugation of the
+cobalt-oxygen layer decreases, the LCOs evolve from a high-spin (HS)
+superexchange-coupled antiferromagnetic (AFM) insulator to an almost-HS
+AFM/ferromagnetic (FM) competing system where the FM coupling is mediated via
+the p-d exchange by an increasing amount of delocalized pd\sigma holes having
+mainly the planar O 2p character. It is tentatively suggested that the
+delocalized holes more than 0.3 per CoO_{2} basal square are likely necessary
+for the insulator-metal and/or AFM-FM transitions in the corrugation-weakened
+LCOs. A phase control may be realized in LCOs by varying the plane corrugation
+(thus modifying the hole concentration) through an ionic-size change of the
+neighboring layers on both sides of the cobalt-oxygen layer. In addition, a few
+experiments are suggested for a check of the present model and picture.",0210369v1
+2002-10-30,"Oxygen Stoichiometry in Co-1212, Co-1222 and Co-1232 of Homologous Series Co-12s2 of Category-B Layered Copper Oxides","Here results of a systematic study on oxygen stoichiometry are reported for
+the first three members of the novel CoSr2(Y,Ce)sCu2O5+2s or Co-12s2 homologous
+series, i.e. Co-1212, Co-1222 and Co-1232 phases with a
+SrO-CoO1-SrO-CuO2-(Y,Ce)-[O2-(Y,Ce)]s-1-CuO2 layered structure. The oxygen
+content was precisely determined by two independent chemical techniques:
+coulometric Cu+/Cu2+ titration and iodometric titration. Furthermore, oxygen
+stability/tunability was investigated by means of oxygenative and reductive
+an-nealings carried out in a thermobalance. It was revealed that all the three
+phases are rather stoichiometric in oxygen content and stable against both
+oxygenative and reductive an-nealings. The present results for the Co-12s2
+homologous series suggest that not only the CoO1 charge reservoir but also the
+nominally oxygen-stoichiometric B-[O2-B]s-1 fluo-rite block, that is the
+characteristic structural element for the Co-12s2 (s > 1) phases and all other
+layered copper oxides of category-B [H. Yamauchi and M. Karppinen, Superlatt.
+Microstructr. 21A (1997) 128] is non-tunable in terms of the oxygen content.",0210660v1
+2002-12-13,The effect of a nucleating agent on lamellar growth in melt-crystallizing polyethylene oxide,"The effects of a (non co-crystallizing) nucleating agent on secondary
+nucleation rate and final lamellar thickness in isothermally melt-crystallizing
+polyethylene oxide are considered. SAXS reveals that lamellae formed in
+nucleated samples are thinner than in the pure samples crystallized at the same
+undercoolings. These results are in quantitative agreement with growth rate
+data obtained by calorimetry, and are interpreted as the effect of a local
+decrease of the basal surface tension, determined mainly by the nucleant
+molecules diffused out of the regions being about to crystallize. Quantitative
+agreement with a simple lattice model allows for some interpretation of the
+mechanism.",0212328v1
+2003-02-10,Dinitrosyl formation as an intermediate stage of the reduction of NO in the presence of MoO_3,"We present first-principles calculations in the framework of
+density-functional theory and the pseudopotential approach, aiming to model the
+intermediate stages of the reduction of NO in the presence of MoO$_3$(010). In
+particular, we study the formation of dinitrosyl, which proves to be an
+important intermediate stage in the catalytic reduction. We find that the
+replacement of an oxygen of MoO$_3$ by NO is energetically favorable, and that
+the system lowers further its energy by the formation of (NO)$_2$. Moreover,
+the geometry and charge distribution for the adsorbed dinitrosyl indicates a
+metal-oxide mediated coupling between the two nitrogen and the two oxygen
+atoms. We discuss the mechanisms for the dinitrosyl formation and the role of
+the oxide in the reaction.",0302189v1
+2003-02-20,Correlation and surface effects in Vanadium Oxides,"Recent photoemission experiments have shown strong surface modifications in
+the spectra from vanadium oxides as (V,Cr)_2O_3 or
+  (Sr,Ca)VO_3. The effective mass is enhanced at the surface and the coherent
+part of the surface spectrum is narrowed as compared to the bulk. The
+quasiparticle weight is more sensitive at the surface than in the bulk against
+bandwidth variations. We investigate these effects theoretically considering
+the single-band Hubbard model for a film geometry. A simplified dynamical
+mean-field scheme is used to calculate the main features of the interacting
+layer-dependent spectral function. It turns out that the experimentally
+confirmed effects are inherent properties of a system of strongly correlated
+electrons. The reduction of the weight and the variance of the coherent part of
+the surface spectrum can be traced back to the reduced surface coordination
+number. Surface correlation effects can be strongly amplified by changes of the
+hopping integrals at the surface.",0302427v1
+2003-03-19,Is the Superconductiong State for the Cuprates Reached Through a Percolation Transition?,"Several recent experiments have revealed that the charge density $\rho$ in a
+given compound (mostly underdoped) is intrinsic inhomogeneous with large
+nanoscale spatial variations. Therefore it is appropriate to define a local
+charge density $\rho(r)$. These differences in the local charge concentration
+yield insulator and metallic regions, either in an intrinsic granular or in a
+stripe morphology. In the metallic region, the inhomogeneous charge density
+produces spatial or local distributions of superconducting critical
+temperatures $T_c(r)$ and zero temperature gap $\Delta_0(r)$. We propose that
+the superconducting phase in high-$T_c$ oxides is reached when the temperature
+reachs a value which superconduction regions with different critical
+temperatures percolates. We show also that this novel approach is able to
+reproduce the phase diagram for a family of cuprates and provides new insights
+on several experimental features of high-$T_c$ oxides",0303398v1
+2003-03-21,Curie temperature enhancement of electron doped Sr$_2$FeMoO$_6$ perovskites studied by photoemission spectroscopy,"We report here on the electronic structure of electron-doped half-metallic
+ferromagnetic perovskites such Sr$_{2-x}$La$_x$FeMoO$_6$ ($x$=0-0.6) as
+obtained from high-resolved valence-band photoemission spectroscopy (PES). By
+comparing the PES spectra with band structure calculations, a distinctive peak
+at the Fermi level (E$_F$) with predominantly (Fe+Mo) t$_{2g}^\downarrow$
+character has been evidenced for all samples, irrespectively of the $x$ values
+investigated. Moreover, we show that the electron doping due to the La
+substitution provides selectively delocalized carriers to the
+t$_{2g}^\downarrow$ metallic spin channel. Consequently, a gradual rising of
+the density of states at the E$_F$ has been observed as a function of the La
+doping. By changing the incoming photon energy we have shown that electron
+doping mainly rises the density of states of Mo parentage. These findings
+provide fundamental clues for understanding the origin of ferromagnetism in
+these oxides and shall be of relevance for tailoring oxides having still higher
+T$_C$.",0303464v1
+2003-04-04,The Pd(100)-(SQRT(5) x SQRT(5) R27^o)-O surface oxide revisited,"Combining high-resolution core-level spectroscopy (HRCLS), scanning tunneling
+microscopy (STM) and density-functional theory
+  (DFT) calculations we reanalyze the Pd(100)-(SQRT(5) x SQRT(5) R27^o)-O
+surface oxide phase. We find that the prevalent structural model, a rumpled
+PdO(001) film suggested by previous low energy electron diffraction (LEED) work
+(M. Saidy et al.,
+  Surf. Sci. 494, L799 (2001)), is incompatible with all three employed
+methods. Instead, we suggest the two-dimensional film to consist of a strained
+PdO(101) layer on top of Pd(100). LEED intensity calculations show that this
+model is compatible with the experimental data of Saidy et al.",0304107v1
+2003-04-22,Sodium and oxygen nonstoichiometry and thermoelectric properties of NaxCoO2+d,"The sodium-cobalt oxide NaxCoO2+d is a promising candidate for thermoelectric
+applications since it may possess simultaneously large thermoelectric power and
+low resistivity. It is difficult to understand the simultaneous appearance of
+the two properties within the framework of conventional one-electron models. It
+has been suggested that the spin state of cobalt ions plays a crucially
+important role in enhancing the thermoelectric power. In order to study the
+relationship between the cobalt spin state and thermoelectric properties,
+NaxCoO2+d samples with precisely controlled sodium and oxygen contents are
+indispensable. Recently, we established an uncon-ventional sample-synthesis
+method that enables us to precisely control the Na content in NaxCoO2+d
+samples. In this article, we discuss the effects of sodium and oxygen
+nonstoichiometry on the thermoelectric properties of NaxCoO2+d.",0304479v1
+2003-04-24,Room Temperature Electrochemical Synthesis of Hg-1212 Superconducting Thin Films,"In the present investigation, the novel two-step electrochemical process of
+room temperature synthesis of Hg-1212 superconducting films has been developed
+and reported first time. Electrochemical parameters were optimized by studying
+cyclic voltammetry (CV), linear sweep voltammetry (LSV) and chronoamperometry
+(CA) for the deposition of Hg-Ba-Ca-Cu alloy at room temperature. Current time
+transient showed progressive growth with hemispheriodal granules, which were
+then revealed by scanning electron microscopy (SEM). Stoichiometric
+electrocrystallization to get Hg1Ba2Ca1Cu2O6+x (Hg-1212) was completed by
+electrochemically intercalating oxygen species into Hg-Ba-Ca-Cu alloy at room
+temperature. The oxygen content in the samples was varied by varying the
+electrochemical oxidation period and the changes in the crystal structure,
+microstructure, and superconducting transition temperature (Tc) and critical
+current density (Jc) were recorded. The films oxidized for 28 min showed Tc =
+104.7 K with Jc = 1.437 x 103 A/cm2. The dependence of superconducting
+parameters on oxygen content is correlated with structure property relations
+and reported in this paper.",0304566v1
+2003-05-03,Synthesis of Single Phase Hg-1223 High Tc Superconducting Films With Multistep Electrolytic Process,"We report the multistep electrolytic process for the synthesis of high Tc
+single phase HgBa2Ca2Cu3O8+&#61540; (Hg-1223) superconducting films. The
+process includes : i) deposition of BaCaCu precursor alloy, ii) oxidation of
+BaCaCu films, iii) electrolytic intercalation of Hg in precursor BaCaCuO films
+and iv) electrochemical oxidation and annealing of Hg-intercalated BaCaCuO
+films to convert into Hg1Ba2Ca2Cu3O8+&#61540; (Hg-1223). Films were
+characterized by thermo-gravimetric analysis (TGA) and differential thermal
+analysis (DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM).
+The electrolytic intercalation of Hg in BaCaCuO precursor is proved to be a
+novel alternative to high temperature-high pressure mercuration process. The
+films are single phase Hg-1223 with Tc = 121.5 K and Jc = 4.3 x 104 A/cm2.",0305059v1
+2003-05-23,Drain Voltage Scaling in Carbon Nanotube Transistors,"While decreasing the oxide thickness in carbon nanotube field-effect
+transistors (CNFETs) improves the turn-on behavior, we demonstrate that this
+also requires scaling the range of the drain voltage. This scaling is needed to
+avoid an exponential increase in Off-current with drain voltage, due to
+modulation of the Schottky barriers at both the source and drain contact. We
+illustrate this with results for bottom-gated ambipolar CNFETs with oxides of 2
+and 5 nm, and give an explicit scaling rule for the drain voltage. Above the
+drain voltage limit, the Off-current becomes large and has equal electron and
+hole contributions. This allows the recently reported light emission from
+appropriately biased CNFETs.",0305570v1
+2003-05-28,Structural Studies on Semiconducting Hydrogenated Amorphous Silicon Oxide Films,"In hydrogenated amorphous silicon oxide (a-SiO:H) films, incorporation of
+oxygen enhances optical gap due to a large number of St-O-Si bond formation,
+which lies deep into valence band states. An induction effect of this Si-O on
+other bonds within the network also takes place. At higher oxygen content
+micro-void forms and bonded hydrogen accumulates in di and/or polyhydride form.
+At this stage a phase separation of Si-rich and O-rich region taking place. A
+peak shift of absorption spectra within 1850 - 2250 cm-1, towards higher wave
+number is continuous. A gradual increase and broadening of 850 cm-1 absorption
+band on both sides of peak position indicate higher structural disorder in
+network formation. It may be considered that the stretching vibration of-OH
+bonded to Si gives rise to 780 cm-1 absorption band. This Si-OH formation is
+beneficial which prevents deterioration in photosensitivity due to reduction in
+bonded hydrogen content. Hydrogen content is found reducing as oxygen content
+increases from zero to ~15 at.%. A systematic study is carried out to correlate
+the optoelectronic property with local atomic arrangement.",0305636v1
+2003-06-06,Non-linear electrical response in a charge/orbital ordered $\Pr_{0.63}$Ca$_{0.37}$MnO$_3$ crystal : the charge density wave analogy,"Non-linear conduction in a charge-ordered manganese oxide
+Pr$_{0.63}$Ca$_{0.37}$MnO$_3$ is reported. To interpret such a feature, it is
+usually proposed that a breakdown of the charge or orbitally ordered state is
+induced by the current. The system behaves in such a way that the bias current
+may generate metallic paths giving rise to resistivity drop. One can describe
+this feature by considering the coexistence of localized and delocalized
+electron states with independent paths of conduction. This situation is
+reminiscent of what occurs in charge density wave systems where a similar
+non-linear conduction is also observed. In the light of recent experimental
+results suggesting the development of charge density waves in charge and
+orbitally ordered manganese oxides, a phenomenological model for charge density
+waves motion is used to describe the non-linear conduction in
+Pr$_{0.63}$Ca$_{0.37}$MnO$_3$. In such a framework, the non-linear conduction
+arises from the motion of the charge density waves condensate which carries a
+net electrical current.",0306161v1
+2003-06-10,Vortex Core Excitations in Superconductors with Frustrated Antiferromagnetism,"Motivated by recent discovery of cobalt oxide and organic superconductors, we
+apply an effective model with strong antiferromagnetic and superconducting
+pairing interaction to a related lattice structure. It is found that the
+antiferromagnetism is highly frustrated and a broken-time-reversal-symmetry
+chiral $d+id^{\prime}$-wave pairing state prevails. In the mixed state, we have
+solved the local electronic structure near the vortex core and found no local
+induction of antiferromagnetism. This result is in striking contrast to the
+case of copper oxide superconductors. The calculated local density of states
+indicates the existence of low-lying quasiparticle bound states inside the
+vortex core, due to a fully gapped chiral pairing state. The prediction can be
+directly tested by scanning tunneling microscopy.",0306253v1
+2003-06-26,Vibrational edge modes in intrinsically inhomogeneous doped transition metal oxides,"By applying an unrestriced Hartree-Fock approximation and a Random Phase
+approximation to multiband Peierls-Hubbard Hamiltonians, we determine the
+phonon mode structure in models of transition metal oxides in the presence of
+intrinsic nanoscale inhomogeneities induced by hole doping. We identify low
+frequency $local$ vibrational modes pinned to the interface between regions of
+distinct electronic structure and separated in frequency from the band of
+extended phonons. A major characteristic of these ``edge'' modes is that their
+energy is essentially insensitive to the doping level, while their intensity
+increases with the density of interfaces (and thus doping level). We argue that
+the presence of such modes is a typical feature of systems with phase
+separation, including cuprates, nickelates, manganites, and bismuthates. We
+specifically address the experimental signatures of these modes in lattice
+inelastic neutron scattering.",0306672v1
+2003-07-02,Adsorption of Methanol on Aluminum Oxide: A Density Functional Study,"Theoretical calculations based on density functional theory have made
+significant contributions to our understanding of metal oxides, their surfaces,
+and the binding of molecules at these surfaces. In this paper we investigate
+the binding of methanol at the alpha-Al2O3(0001) surface using first-principles
+density functional theory. We calculate the molecular adsorption energy of
+methanol to be E^g_ads=1.03 eV/molecule. Taking the methanol-methanol
+interaction into account, we obtain the adsorption energy E_ads=1.01
+eV/molecule. Our calculations indicate that methanol adsorbs chemically by
+donating electron charge from the methanol oxygen to the surface aluminum. We
+find that the surface atomic structure changes upon adsorption, most notably
+the spacing between the outermost Al and O layers changes from 0.11 Angstrom to
+0.33 Angstrom.",0307039v1
+2003-07-23,Electronic States in Two-Dimensional Triangular Cobalt Oxides: Role of Electronic Correlation,"We obtain the electronic states and structures of two-dimensional cobalt
+oxides, Na$_{x}$CoO$_{2}$ (x=0, 0.35, 0.5 and 0.75) by utilizing the
+full-potential linear muffin-tin orbitals (FP-LMTO) methods, from which some
+essential electronic interaction parameters are estimated: the bare on-site
+Coulomb interaction of cobalt U$_{dd}$=7.5 eV renormalizes to 5 eV for x=0.35,
+the $pd$ hybridizations t$_{pd\sigma}$ and t$_{pd\pi}$ are -1.40 and 0.70 eV,
+respectively. The density of states at E$_{F}$ decreases from 6-7 states/eV in
+the local density approximation (LDA) to about 1.0 states/eV in the LDA+U
+scheme. The role of the intercalation of water molecules and the microscopic
+mechanism of the superconductivity in Na$_{0.35}$CoO$_{2}$$\cdot$mH$_{2}$O is
+discussed.",0307560v2
+2003-08-06,On the break in the single-particle energy dispersions and the `universal' nodal Fermi velocity in the high-temperature copper-oxide superconductors,"Recent data from angle-resolved photoemission experiments published by Zhou
+et al. [Nature, Vol. 423, 398 (2003)] concerning a number of hole-doped
+copper-oxide-based high-temperature superconductors reveal that in the nodal
+directions of the underlying square Brillouin zones (i.e. the directions along
+which the d-wave superconducting gap is vanishing) the Fermi velocities for
+some finite range of k inside the Fermi sea and away from the nodal Fermi
+wavevector k_F are to within an experimental uncertainty of approximately 20%
+the same both in all the compounds investigated and over a wide range of doping
+concentrations and that, in line with earlier experimental observations, at
+some characteristic wavevector k_* away from k_F the Fermi velocities undergo a
+sudden change, with this change (roughly speaking, a finite discontinuity)
+being the greatest (smallest) in the case of underdoped (overdoped) compounds.
+In this paper we present a rigorous analysis concerning the implications of
+these observations. [Short abstract]",0308090v2
+2003-08-25,Quantum Transport in a Nanosize Silicon-on-Insulator Metal-Oxide-Semiconductor,"An approach is developed for the determination of the current flowing through
+a nanosize silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect
+transistors (MOSFET). The quantum mechanical features of the electron transport
+are extracted from the numerical solution of the quantum Liouville equation in
+the Wigner function representation. Accounting for electron scattering due to
+ionized impurities, acoustic phonons and surface roughness at the Si/SiO2
+interface, device characteristics are obtained as a function of a channel
+length. From the Wigner function distributions, the coexistence of the
+diffusive and the ballistic transport naturally emerges. It is shown that the
+scattering mechanisms tend to reduce the ballistic component of the transport.
+The ballistic component increases with decreasing the channel length.",0308485v1
+2003-09-01,Predicted Performance Advantages of Carbon Nanotube Transistors with Doped Nanotubes as Source/Drain,"Most carbon nanotube field-effect transistors (CNTFETs) directly attach metal
+source/drain contacts to an intrinsic nanotube channel. When the gate oxide
+thickness is reduced, such transistors display strong ambipolar conduction,
+even when the Schottky barrier for electrons (or for holes) is zero. The
+resulting leakage current, which increases exponentially with the drain
+voltage, constrains the potential applications of such devices. In this paper,
+we use numerical simulations to show that if CNT based
+metal-oxide-semiconductor (MOS) FETs can be achieved by using heavily doped CNT
+sections as source and drain, ambipolar conduction will be suppressed, leakage
+current will be reduced, and the scaling limit imposed by source-drain
+tunneling will be extended. By eliminating the Schottky barrier between the
+source and channel, the transistor will be capable of delivering more
+on-current. The leakage current of such devices will be controlled by the full
+bandgap of CNTs (instead of half of the bandgap for SB CNTFETs) and
+band-to-band tunneling. These factors will depend on the diameter of nanotubes
+and the power supply voltage.",0309039v1
+2003-09-09,An explanation for a universality of transition temperatures in families of copper oxide superconductors,"A remarkable mystery of the copper oxide high-transition-temperature (Tc)
+superconductors is the dependence of Tc on the number of CuO2 layers, n, in the
+unit cell of a crystal. In a given family of these superconductors, Tc rises
+with the number of layers, reaching a peak at n=3, and then declines: the
+result is a bell-shaped curve. Despite the ubiquity of this phenomenon, it is
+still poorly understood and attention has instead been mainly focused on the
+properties of a single CuO2 plane. Here we show that the quantum tunnelling of
+Cooper pairs between the layers simply and naturally explains the experimental
+results, when combined with the recently quantified charge imbalance of the
+layers and the latest notion of a competing order nucleated by this charge
+imbalance that suppresses superconductivity. We calculate the bell-shaped curve
+and show that, if materials can be engineered so as to minimize the charge
+imbalance as n increases, Tc can be raised further.",0309209v3
+2003-09-30,Hydrogen adsorption at RuO2(110),"The structural, vibrational, energetic and electronic properties of hydrogen
+at the stoichiometric RuO2(110) termination are studied using density
+functional theory. The oxide surface is found to stabilize both molecular and
+dissociated H2. The most stable configuration in form of hydroxyl groups
+(monohydrides) at the undercoordinated O^br surface anions is at low
+temperatures accessed via a molecular state at the undercoordinated Ru^cus
+atoms (dihydrogen) and a second precursor in form of a water-like species
+(dihydride) at the O^br sites. This complex picture of the low-temperature
+dissociation kinetics of H2 at RuO2(110) is in agreement with existing data
+from high-resolution energy-loss spectroscopy and temperature programmed
+desorption. Hydrogen adsorption at O^br sites increases the reactivity of the
+neighboring Ru^cus sites, which are believed to be the active sites in
+catalytic oxidation reactions.",0309714v1
+2003-11-29,Surface plasmon resonances in the absorption spectra of nanocrystalline cupric oxide,"Optical absorption spectra of nanocrystalline cupric oxide CuO samples,
+obtained using the converging spherical shock wave procedure, reveal
+significant spectral weight red-shift as compared with spectra of single
+crystalline CuO samples. In addition, some of these samples manifest the
+remarkable temperature-dependent ""peak-dip-hump"" feature near 1.3-1.6 eV. The
+minimal model suggested to explain both effects implies the nanoceramic CuO to
+be a system of two species of identical metallic-like droplets with volume
+fractions p1 >> p2 and damping parameters gamma1 >> gamma2, respectively,
+dispersed in an effective insulating matrix. In other words, both effects are
+assigned to the surface plasmon (Mie) resonances due to a small volume fraction
+of metallic-like nanoscale droplets with Drude optical response embedded in the
+bare insulating medium. Simple effective medium theory is shown to provide the
+reasonable description of the experimental spectra.",0312009v1
+2004-03-22,Vibrational edge modes in intrinsically heterogeneous doped transition metal oxides,"By applying an unrestricted Hartree-Fock and a Random Phase approximations to
+a multiband Peierls-Hubbard Hamiltonian, we study the phonon mode structure in
+models of transition metal oxides in the presence of intrinsic nanoscale
+inhomogeneities induced by hole doping. We identify low frequency $local$
+vibrational modes pinned to the sharp interfaces between regions of distinct
+electronic structure (doped and undoped) and separated in frequency from the
+band of extended phonons. A characteristic of these ``edge'' modes is that
+their energy is essentially insensitive to the doping level. We discuss the
+experimental manifestations of these modes in inelastic neutron scattering, and
+also in spin and charge excitation spectra.",0403525v2
+2004-03-24,Ab initio Study of Valley Line on a Total-Energy Surface for Zone-Center Distortions of Ferroelectric Perovskite Oxides BaTiO3 and PbTiO3,"An ab initio structure optimization technique is newly developed to determine
+the valley line on a total-energy surface for zone-center distortions of
+ferroelectric perovskite oxides and is applied to barium titanate BaTiO3 and
+lead titanate PbTiO3. The proposed technique is an improvement over King-Smith
+and Vanderbilt's scheme [Phys. Rev. B 49, p.5828 (1994)] of evaluating total
+energy as a function of the amplitude of atomic displacements. The results of
+numerical calculations show that total energy can be expressed as a
+fourth-order function of the amplitude of atomic displacements in BaTiO3 but
+not in PbTiO3.",0403603v1
+2004-05-10,The chemistry of La on the Si(001) surface,"This paper reports state-of-the-art electronic structure calculations of La
+adsorption on the Si(001) surface. We predict La chains in the low coverage
+limit, which condense in a stable phase at a coverage of 1/5 monolayer. At 1/3
+monolayer we predict a chemically rather inert, stable phase. La changes its
+oxidation state from La(3+) at lower coverages to La(2+) at coverages beyond
+1/3 monolayer. In the latter oxidation state, one electron resides in a state
+with a considerable contribution from La-d and f states.",0405192v2
+2004-06-04,Spin entropy as the likely source of enhanced thermopower in $\rm\bf Na_xCo_2O_4,"In an electric field, the flow of electrons in a solid produces an entropy
+current in addition to the familiar charge current. This Peltier effect
+underlies all thermoelectric refrigerators. The upsurge in thermoelectric
+cooling applications has led to a search for more efficient Peltier materials
+and to renewed theoretical interest in how electron-electron interaction may
+enhance the thermopower $Q$ of materials such as the transition-metal oxides
+\cite{Mahan,Beni,Kotliar,Chaikin}. An important factor in this enhancement is
+the electronic spin entropy, which is predicted \cite{Chaikin,Kwak,KwakChaikin}
+to dominate the entropy current. Here we report evidence for such suppression
+in the layered oxide $\rm Na_xCo_2O_4$, and present evidence that it is a
+strong-correlation effect.",0406125v1
+2004-06-22,Electronic structure properties and BCS superconductivity in beta-pyrochlore oxides: KOs_2O_6,"We report a first-principles density-functional calculation of the electronic
+structure and properties of the recently discovered superconducting
+beta-pyrochlore oxide KOs_2O_6. We find that the electronic structure near the
+Fermi energy E_F is dominated by strongly hybridized Os-5d and O-2p states. A
+van Hove singularity very close to E_F leads to a relatively large density of
+states at E_F, and the Fermi surface exhibits strong nesting along several
+directions. These features could provide the scattering processes leading to
+the observed anomalous temperature dependence of the resistivity and to the
+rather large specific heat mass enhancement we obtain from the calculated
+density of states and the observed specific heat coefficient. An estimate of
+T_c within the framework of the BCS theory of superconductivity taking into
+account the possible effects of spin fluctuations arising from nesting yields
+the experimental value.",0406538v1
+2004-07-28,Fractal Self-Assembled Nanostructures on Monocrystalline Silicon Surface,"We present ultra-shallow diffusion profiles performed by short-time diffusion
+of boron from the gas phase using controlled surface injection of
+self-interstitials and vacancies into the n-type Si(100) wafers. The diffusion
+profiles of this art are found to consist of both longitudinal and lateral
+silicon quantum wells of the p-type that are self-assembled between the alloys
+of microdefects, which are produced by previous oxidation. These alloys appear
+to be passivated during short-time diffusion of boron thereby forming neutral
+del'ta barriers. The fractal type self-assembly of microdefects is found to be
+created by varying the thickness of the oxide overlayer, which causes the
+system of microcavities embedded in the quantum well plane.",0407722v1
+2004-08-09,Resonant two-photon excitation of 1s paraexcitons in Cuprous Oxide,"We have created paraexcitons in Cuprous Oxide via resonant two-photon
+generation, and examined their population dynamics by means of time-correlated
+single photon detection. Confining the excitons to a constant volume in a
+harmonic potential trap made with inhomogeneous applied stress along the [001]
+axis, we find that paraexcitons are created directly, and orthoexcitons appear
+primarily through the well-known excitonic Auger process. Hot excitons are also
+created via a three-photon process when the IR laser is non-resonant. Also we
+generate excitons with two colliding pulses, and the luminescence is weaker
+than that from one beam excitation with same total laser power. These results
+show that resonant one-beam two-photon generation of paraexcitons is a
+promising way to pursue Bose-Einstein condensation of paraexcitons.",0408188v3
+2004-09-01,Decoherence of a Josephson qubit due to coupling to two level systems,"Noise and decoherence are major obstacles to the implementation of Josephson
+junction qubits in quantum computing. Recent experiments suggest that two level
+systems (TLS) in the oxide tunnel barrier are a source of decoherence. We
+explore two decoherence mechanisms in which these two level systems lead to the
+decay of Rabi oscillations that result when Josephson junction qubits are
+subjected to strong microwave driving. (A) We consider a Josephson qubit
+coupled resonantly to a two level system, i.e., the qubit and TLS have equal
+energy splittings. As a result of this resonant interaction, the occupation
+probability of the excited state of the qubit exhibits beating. Decoherence of
+the qubit results when the two level system decays from its excited state by
+emitting a phonon. (B) Fluctuations of the two level systems in the oxide
+barrier produce fluctuations and 1/f noise in the Josephson junction critical
+current I_o. This in turn leads to fluctuations in the qubit energy splitting
+that degrades the qubit coherence. We compare our results with experiments on
+Josephson junction phase qubits.",0409006v1
+2004-09-04,A `checkerboard' electronic crystal state in lightly hole-doped Ca_{2-x}Na_{x}CuO_{2}Cl_{2},"The phase diagram of hole-doped copper oxides shows four different electronic
+phases existing at zero temperature. Familiar among these are the Mott
+insulator, high-transition-temperature superconductor and metallic phases. A
+fourth phase, ofunknown identity, occurs at light doping along the
+zero-temperature bound of the `pseudogap' regime. This regime is rich in
+peculiar electronic phenomena, prompting numerous proposals that it contains
+some form of hidden electronic order. Here we present low-temperature
+electronic structure imaging studies of a lightly hole-doped copper oxide:
+Ca_{2-x}Na_{x}CuO_{2}Cl_{2}. Tunnelling spectroscopy (at energies |E|>100 meV)
+reveals electron extraction probabilities greatly exceeding those for
+injection, as anticipated for a doped Mott insulator. However, for |E|<100 meV,
+the spectrum exhibits a V-shaped energy gap centred on E=0. States within this
+gap undergo intense spatial modulations, with the spatial correlations of a
+four CuO_{2}-unit-cell square checkerboard, independent of energy. Intricate
+atomic-scale electronic structure variations also exist within the
+checkerboard. These data are consistent with an unanticipated crystalline
+electronic state, possibly the hidden electronic order, existing in the
+zero-temperature pseudogap regime of Ca_{2-x}Na_{x}CuO_{2}Cl_{2}.",0409102v1
+2004-09-23,A user-friendly approach to local anodic oxidation,"A home made DSP-controlled scanning probe microscope (SPM) system has been
+developed and its utilization as a tool for lithography on nanometer scale is
+reported. User-friendly graphic interface allows to directly perform
+nanolithography importing a bitmap pattern on previously-imaged sample region,
+otherwise moving in real time the probe using an ordinary mouse, acting as a
+pantograph from macroscopic down to nanometer scale, taking advantage from an
+absolute-positioning stage. Any measured property of the sample can be used by
+the lithographic interface to realize interactive patterning of the sample.
+Moreover, the 'contour-mode' permits to move tip at a fixed relative tip-sample
+distance, exploiting at each step the previously-acquired topographic signal.
+The instrument has been successfully employed in order to perform local anodic
+oxidation (LAO) lithography on semiconducting substrates.",0409608v1
+2004-10-05,Optical Properties of Excitons in ZnO-based Quantum Well Heterostructures,"Recently the developments in the field of II-VI-oxides have been spectacular.
+Various epitaxial methods has been used to grow epitaxial ZnO layers. Not only
+epilayers but also sufficiently good-quality multiple quantum wells (MQWs) have
+also been grown by laser molecular-beam epitaxy (laser-MBE). We discuss mainly
+the experimental aspect of the optical properties of excitons in ZnO-based MQW
+heterostructures. Systematic temperature-dependent studies of optical
+absorption and photoluminescence in these MQWs were used to evaluate the
+well-width dependence and the composition dependence of the major excitonic
+properties. Based on these data, the localization of excitons, the influence of
+exciton-phonon interaction, and quantum-confined Stark effects are discussed.
+  The optical spectra of dense excitonic systems are shown to be determined
+mainly by the interaction process between excitons and biexcitons. The
+high-density excitonic effects play a role for the observation of
+room-temperature stimulated emission in the ZnO MQWs. The binding energies of
+exciton and biexciton are enhanced from the bulk values, as a result of
+quantum-confinement effects.",0410120v2
+2004-10-18,Structural Behavior of Non-Oxide Perovskite Superconductor MgCNi$_{3}$ at Pressures up to 32 GPa,"We report the pressure dependence of the structural parameters of the
+non-oxide perovskite superconductor MgCNi$_{3}$ up to 32 GPa using a diamond
+anvil cell and synchrotron x-rays at room temperature. The structure of the
+compound remains in the Pm-3m cubic symmetry throughout the pressure range. The
+bulk modulus $B_{0}=156.9\pm0.2$GPa with $B_{0}^{\prime}=9.8$obtained by
+fitting the pressure-volume data is in good agreement with theoretical
+calculations reported earlier. An anomalous shift of the (111) and (200) lines
+observed above 9 GPa indicates a possible local short range distortion that is
+consistent with earlier studies.",0410430v1
+2004-11-05,X-ray photoelectron spectroscopy studies of non-stoichiometric superconducting NbB2+x,"Polycrystalline samples of NbB2+x with nominal composition (B/Nb) = 2.0, 2.1,
+2.2, 2.3, 2.4 and 2.5 were studied by X-ray photoelectron spectroscopy (XPS).
+The spectra revealed Nb and B oxides on the surface of the samples, mainly B2O3
+and Nb2O5. After Ar ion etching the intensity of Nb and B oxides decreased. The
+Nb 3d5/2 and B 1s core levels associated with the chemical states (B/Nb) were
+identified and they do not change with etching time. The Binding Energy of the
+Nb 3d5/2 and B 1s core levels increase as boron content increases, suggesting a
+positive chemical shift in the core levels. On the other hand, analysis of
+Valence Band spectra showed that the contribution of the Nb 4d states slightly
+decreased while the contribution of the B 2p(pi) states increased as the boron
+content increased. As a consequence, the electronic and superconducting
+properties were substantially modified, in good agreement with band-structure
+calculations.",0411131v3
+2004-12-07,Breakdown of One-Paramater Scaling in Quantum Critical Scenarios for the High-Temperature Copper-oxide Superconductors,"We show that if the excitations which become gapless at a quantum critical
+point also carry the electrical current, then a resistivity linear in
+temperature, as is observed in the copper-oxide high-temperature
+superconductors, obtains only if the dynamical exponent, $z$, satisfies the
+unphysical constraint, $z<0$. At fault here is the universal scaling hypothesis
+that, at a continuous phase transition, the only relevant length scale is the
+correlation length. Consequently, either the electrical current in the normal
+state of the cuprates is carried by degrees of freedom which do not undergo a
+quantum phase transition, or quantum critical scenarios must forgo this basic
+scaling hypothesis and demand that more than a single correlation length scale
+is necessary to model transport in the cuprates.",0412179v2
+2005-01-10,Orbital Insulators and Orbital Order-disorder Induced Metal-Insulator Transition in Transition-Metal Oxides,"The role of orbital ordering on metal-insulator transition of
+transition-metal oxides is investigated by the cluster self-consistent field
+approach in the strong correlation regime. A clear dependence of the insulating
+gap on the orbital order parameter is found in the single-particle excitation
+spectra. The thermal fluctuation drives the orbital order-disorder transition,
+diminishes the gap and leads to the metal-insulator transition. The interplay
+between spins and orbits results in unusual temperature dependence of the
+orbital polarization in the orbital insulator, which can be seen in the
+resonant x-ray scattering intensity.",0501155v2
+2005-02-21,High pressure effects on the superconductivity of beta-pyrochlore oxides AOs2O6,"High pressure effects on the superconducting transitions of beta-pyrochlore
+superconductors AOs2O6 (A = Cs, Rb, K) are studied by measuring resistivity
+under high pressures up to 10 GPa. The superconducting transition temperature
+Tc first increases with increasing pressure in all the compounds and then
+exhibits a broad maximum at 7.6 K (6 GPa), 8.2 K (2 GPa) and 10 K (0.6 GPa) for
+A = Cs, Rb and K, respectviely. Finally, the superconductivity is suppressed
+completely at a critical pressure near 7 GPa and 6 GPa for A = Rb and K and
+probably above 10 GPa for A = Cs. Characteristic changes in the coefficinet A
+of the T2 term in resistivity and residual resistivity are observed, both of
+which are synchronized with the corresponding change in Tc. It is suggested
+that electron correlations and certain quantum fluctuations play important
+roles in the occurrence or suppression of superconductivity in the
+beta-pyrochlore oxides.",0502490v1
+2005-03-03,The Schottky defect formation energy in MgO calculated by diffusion Monte Carlo,"The energetics of point defects in oxide materials plays a major role in
+determining their high-temperature properties, but experimental measurements
+are difficult, and calculations based on density functional theory (DFT) are
+not necessarily reliable. We report quantum Monte Carlo (QMC) calculations of
+the formation energy $E_{\rm S}$ of Schottky defects in MgO, which demonstrate
+the feasibility of using this approach to overcome the deficiencies of DFT. In
+order to investigate system-size errors, we also report DFT calculations of
+$E_{\rm S}$ on repeating cells of up to $\sim 1000$ atoms, which indicate that
+QMC calculations on systems of only 54 atoms should yield high precision. The
+DFT calculations also provide the relaxed structures used in the variational
+and diffusion Monte Carlo calculations. For MgO, we find $E_{\rm S}$ to be in
+close agreement with results from DFT and from model interaction potentials,
+and consistent with the scattered experimental values. The prospects for
+applying the same approach to transition metal oxides such as FeO are
+indicated.",0503074v1
+2005-03-15,Physics of thin-film ferroelectric oxides,"This review covers the important advances in recent years in the physics of
+thin film ferroelectric oxides, the strongest emphasis being on those aspects
+particular to ferroelectrics in thin film form. We introduce the current state
+of development in the application of ferroelectric thin films for electronic
+devices and discuss the physics relevant for the performance and failure of
+these devices. Following this we cover the enormous progress that has been made
+in the first principles computational approach to understanding ferroelectrics.
+We then discuss in detail the important role that strain plays in determining
+the properties of epitaxial thin ferroelectric films. Finally, we look at the
+emerging possibilities for nanoscale ferroelectrics, with particular emphasis
+on ferroelectrics in non conventional nanoscale geometries.",0503372v1
+2005-03-26,Effect of molecular structure and oxidation potential on the device performance of single-carrier organic diodes,"The fabrication of single-carrier organic diodes from a series of sixteen
+molecular materials is reported. We experimentally demonstrate how the
+molecular structure affects the film morphology, and how the film morphology
+influences the diode performance. The compounds, with moderate molecular size
+and dendritic structures, are shown to be more favorable for good device
+performance than those small molecules with symmetry structures. The device
+turn-on voltage is found to be strongly dependent on the molecular first
+oxidation potentials. Independent of different anode materials, no obvious
+interfacial charge/dipole effects are observed in the devices. Our results may
+suggest that singlecarrier organic diode might offer a simple way for screeing
+appropriate molecular materials preferable for practical multilayer devices.",0503629v1
+2005-03-29,First principles study of rare-earth oxides,"The self-interaction-corrected local-spin-density approximation is used to
+describe the electronic structure of dioxides, REO$_2$, and sesquioxides,
+RE$_2$O$_3$, for the rare earths, RE=Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy and Ho.
+The valencies of the rare earth ions are determined from total energy
+minimization. We find Ce, Pr, Tb in their dioxides to have the tetravalent
+configuration, while for all the sesquioxides the trivalent groundstate
+configuration is found to be the most favourable. The calculated lattice
+constants for these valency configurations are in good agreement with
+experiment. Total energy considerations are exploited to show the link between
+oxidation and $f$-electron delocalization, and explain why, among the dioxides,
+only the CeO$_2$, PrO$_2$, and TbO$_2$ exist in nature. Tetravalent NdO$_2$ is
+predicted to exist as a metastable phase - unstable towards the formation of
+hexagonal Nd$_2$O$_3$.",0503667v1
+2005-04-04,Origin of dielectric relaxation observed in complex perovskite oxides Ba(1-x)La(x)Ti(1-x)Cr(x)O3,"Frequency dependence of the dielectric constant of complex perovskite oxide
+Ba(1-x)La(x)Ti(1-x)Cr(x)O3 (BLTC) ceramics with the composition ratio 0.4<= x
+<= 0.7 is precisely measured in the temperature range from 20 K to 300 K, and
+the dielectric relaxation is found to be quite similar to that of CaCu3Ti4O12
+(CCTO), which exhibits the Debye-like frequency dispersion around 100 K. In
+BLTC, the ferroelectric phase transition temperature shifts to lower
+temperature with increase of x, while a remarkable dielectric relaxation newly
+appears at higher temperature region. The dielectric relaxation can be
+explained by an equivalent model of a series of two R-C parallel circuits,
+which corresponds to a heterogeneous structure in the sample with an internal
+barrier layer capacitor. Temperature and frequency dependences of the measured
+dielectric constant are explained well by the model with the
+temperature-dependent electrical conductivity and temperature-independent
+intrinsic dielectric constant. It is also found that the contribution of thin
+layer to the dielectric relaxation in a high temperature region is affected by
+the dc bias field on the sample.",0504064v1
+2005-06-20,Electron correlations and bond-length fluctuations in copper oxides: from Zhang--Rice singlets to correlation bags,"We perform first principles, multiconfiguration calculations on clusters
+including several CuO$_6$ octahedra and study the ground-state electron
+distribution and electron--lattice couplings when holes are added to the
+undoped $d^9 p^6$ configuration. We find that the so-called Zhang--Rice state
+on a single CuO$_4$ plaquette is nearly degenerate with a state whose leading
+configuration is of the form Cu $d^9$-- O $p^5$-- Cu $d^9$. A strong coupling
+between the electronic and nuclear motion gives rise to large inter-site charge
+transfer effects for half-breathing displacements of the oxygen ions. Under the
+assumption of charge segregation into alternating hole-free and hole-rich
+stripes of Goodenough \cite{jbg_02,jbg_03}, our results seem to support the
+vibronic mechanism and the traveling charge-density wave model from
+Refs.\cite{jbg_02,jbg_03} for the superconductivity in copper oxides.",0506511v1
+2005-08-05,Large Second Harmonic Kerr rotation in GaFeO3 thin films on YSZ buffered Silicon,"Epitaxial thin films of gallium iron oxide (GaFeO3) are grown on (001)
+silicon by pulsed laser deposition (PLD) using yttrium-stabilized zirconia
+(YSZ) buffer layer. The crystalline template buffer layer is in-situ PLD grown
+through the step of high temperature stripping of the intrinsic silicon surface
+oxide. The X-ray diffraction pattern shows c-axis orientation of YSZ and b-axis
+orientation of GaFeO3 on Si (100) substrate. The ferromagnetic transition
+temperature (TC ~ 215 K) is in good agreement with the bulk data. The films
+show a large nonlinear second harmonic Kerr rotation of ~15 degrees in the
+ferromagnetic state.",0508159v1
+2005-08-05,Ideally Glassy Hydrogen Bonded Networks,"The axiomatic theory of ideally glassy networks, which has proved effective
+in describing phase diagrams and properties of chalcogenide and oxide glasses
+and their foreign interfaces, is broadened here to include intermolecular
+interactions in hydrogen-bonded polyalcohols such as glycerol, monosaccharides
+(glucose), and the optimal bioprotective hydrogen-bonded disaccharide networks
+formed from trehalose. The methods of Lagrangian mechanics and Maxwellian
+scaffolds are useful at the molecular level when bonding hierarchies are
+characterized by constraint counting similar to the chemical methods used by
+Huckel and Pauling. Whereas Newtonian molecular dynamical methods are useful
+for simulating large-scale interactions for times of order 10 ps, constraint
+counting describes network properties on glassy (almost equilibrated) time
+scales, which may be of cosmological order for oxide glasses, or years for
+trehalose. The ideally glassy network of trehalose may consist of extensible
+tandem sandwich arrays.",0508164v1
+2005-09-01,Complexity in Strongly Correlated Electronic Systems,"A wide variety of experimental results and theoretical investigations in
+recent years have convincingly demonstrated that several transition metal
+oxides and other materials, have dominant states that are not spatially
+homogeneous. This occurs in cases in which several physical interactions --
+spin, charge, lattice, and/or orbital -- are simultaneously active. This
+phenomenon causes interesting effects, such as colossal magnetoresistance, and
+it also appears crucial to understand the high temperature superconductors. The
+spontaneous emergence of electronic nanometer-scale structures in transition
+metal oxides, and the existence of many competing states, are properties often
+associated with complex matter where nonlinearities dominate, such as soft
+materials and biological systems. This electronic complexity could have
+potential consequences for applications of correlated electronic materials,
+because not only charge (semiconducting electronic), or charge and spin
+(spintronics) are of relevance, but in addition the lattice and orbital degrees
+of freedom are active, leading to giant responses to small perturbations.
+Moreover, several metallic and insulating phases compete, increasing the
+potential for novel behavior.",0509041v1
+2005-10-06,Evidence for multiple impurity bands in sodium-doped silicon MOSFETs,"We report measurements of the temperature-dependent conductivity in a silicon
+metal-oxide-semiconductor field-effect transistor that contains sodium
+impurities in the oxide layer. We explain the variation of conductivity in
+terms of Coulomb interactions that are partially screened by the proximity of
+the metal gate. The study of the conductivity exponential prefactor and the
+localization length as a function of gate voltage have allowed us to determine
+the electronic density of states and has provided arguments for the presence of
+two distinct bands and a soft gap at low temperature.",0510145v3
+2005-10-10,"First-principles kinetic Monte Carlo simulations for heterogeneous catalysis, applied to the CO oxidation at RuO2(110)","We describe a first-principles statistical mechanics approach enabling us to
+simulate the steady-state situation of heterogeneous catalysis. In a first step
+density-functional theory together with transition-state theory is employed to
+obtain the energetics of all relevant elementary processes. Subsequently the
+statistical mechanics problem is solved by the kinetic Monte Carlo method,
+which fully accounts for the correlations, fluctuations, and spatial
+distributions of the chemicals at the surface of the catalyst under
+steady-state conditions. Applying this approach to the catalytic oxidation of
+CO at RuO2(110), we determine the surface atomic structure and composition in
+reactive environments ranging from ultra-high vacuum (UHV) to technologically
+relevant conditions, i.e. up to pressures of several atmospheres and elevated
+temperatures. We also compute the CO2 formation rates (turnover frequencies).
+The results are in quantitative agreement with all existing experimental data.
+We find that the high catalytic activity of this system is intimately connected
+with a disordered, dynamic surface ``phase'' with significant compositional
+fluctuations. In this active state the catalytic function results from a
+self-regulating interplay of several elementary processes.",0510234v1
+2005-10-10,Resonance Anomalous Surface X-ray Scattering,"Resonance anomalous surface x-ray scattering (RASXS) technique was applied to
+electrochemical interface studies. It was used to determine the chemical states
+of electrochemically formed anodic oxide monolayers on platinum surface. It is
+shown that RASXS exhibits strong polarization dependence when the surface is
+significantly modified. The polarization dependence is demonstrated for three
+examples; anodic oxide formation, sulfate adsorption, and CO adsorption on
+platinum surfaces. s- and p- polarization RASXS data were simulated with the
+latest version of ab initio multiple scattering calculations (FEFF8.2).
+Elementary theoretical considerations are also presented for the origin of the
+polarization dependence in RASXS.",0510235v1
+2005-10-19,Why Some Interfaces Cannot be Sharp,"A central goal of modern materials physics and nanoscience is control of
+materials and their interfaces to atomic dimensions. For interfaces between
+polar and non-polar layers, this goal is thwarted by a polar catastrophe that
+forces an interfacial reconstruction. In traditional semiconductors this
+reconstruction is achieved by an atomic disordering and stoichiometry change at
+the interface, but in multivalent oxides a new option is available: if the
+electrons can move, the atoms don`t have to. Using atomic-scale electron energy
+loss spectroscopy we find that there is a fundamental asymmetry between
+ionically and electronically compensated interfaces, both in interfacial
+sharpness and carrier density. This suggests a general strategy to design sharp
+interfaces, remove interfacial screening charges, control the band offset, and
+hence dramatically improving the performance of oxide devices.",0510491v1
+2005-10-31,Ab Initio Structural Energetics of Beta-Si3N4 Surfaces,"Motivated by recent electron microscopy studies on the Si3N4/rare-earth oxide
+interfaces, the atomic and electronic structures of bare beta-Si3N4 surfaces
+are investigated from first principles. The equilibrium shape of a Si3N4
+crystal is found to have a hexagonal cross section and a faceted dome-like base
+in agreement with experimental observations. The large atomic relaxations on
+the prismatic planes are driven by the tendency of Si to saturate its dangling
+bonds, which gives rise to resonant-bond configurations or planar sp^2-type
+bonding. We predict three bare surfaces with lower energies than the open-ring
+(10-10) surface observed at the interface, which indicate that
+non-stoichiometry and the presence of the rare-earth oxide play crucial roles
+in determining the termination of the Si3N4 matrix grains.",0510823v1
+2005-11-05,"Charge ordering, stripes and phase separation in manganese perovskite oxides: an STM/STS study","A microscopic characterisation of the phase transitions associated with
+colossal magnetoresistance (CMR) in manganese perovskite oxides is a very
+important ingredient in the quest of understanding its underlying mechanism.
+Scanning tunneling microscopy (STM) is most suitable to investigate some of
+their reported hallmarks, including charge ordering, lattice distortions, and
+electronic phase separation. Here we investigate Bi1-XCaXMnO3 (BCMO) with
+x=0.76. At this composition, BCMO develops an insulating charge-ordered phase
+upon cooling, whose study as a function of temperature will allow identifying
+atomic scale characteristics of the metal-insulator phase transition (MIT). We
+observe distinct atomic scale phases at temperatures above and below the MIT,
+with very different electronic and structural characteristics. Combining STM
+micrographs and current-voltage tunneling characteristics, we find that charge
+ordering correlates both with the local conduction state (metallic or
+insulating) and the local structural order. Furthermore, STM shows coexistence
+of these phases as expected for a first order phase transition.",0511139v1
+2005-11-10,"Thermoelectric properties of the layered Pd oxide R_2PdO_4 (R = La, Nd, Sm and Gd)","We prepared polycrystalline samples of R$_2$PdO$_4$ (R = La, Nd, Sm and Gd)
+using a NaCl-flux technique. The measured resistivity is of the order of
+10$^3-10^4$ $\Omega$cm at room temperature, which is two orders of magnitude
+smaller than the values reported so far. We further studied the substitution
+effects of Ce for Nd in Nd$_{1.9}$Ce$_{0.1}$PdO$_4$, where the substituted Ce
+decreases the resistivity and the magnitude of the thermopower. The activation
+energy gap of 70-80 meV and the effective mass of 15 evaluated from the
+measured data are suitable for thermoelectric materials, but the mobility of
+10$^{-6}$ cm$^2$/Vs is much lower than a typical value of 1-10 cm$^2$/Vs for
+other thermoelectric oxides.",0511245v1
+2005-11-11,"Elasticity and piezoelectricity of zinc oxide crystals, single layers, and possible single-walled nanotubes","The elasticity and piezoelectricity of zinc oxide (ZnO) crystals and single
+layers are investigated from the first-principles calculations. It is found
+that a ZnO thin film less than three Zn-O layers prefers a planar graphite-like
+structure to the wurtzite structure. ZnO single layers are much more flexible
+than graphite single layers in the elasticity and stronger than boron nitride
+single layers in the piezoelectricity. Single-walled ZnO nanotubes (SWZONTs)
+can exist in principle because of their negative binding energy. The
+piezoelectricity of SWZONTs depends on their chirality. For most ZnO nanotubes
+except the zigzag type, twists around the tube axis will induce axial
+polarizations. A possible scheme is proposed to achieve the SWZONTs from the
+solid-vapor phase process with carbon nanotubes as templates.",0511274v3
+2005-11-18,The Parent of Misfit-Layered Cobalt Oxides: [Sr2O2]qCoO2,"Misfit-layered (ML) cobalt oxides of the general formula of [MmA2Om+2]qCoO2
+have been proven to be efficient thermoelectric materials as the structure is
+capable in accommodating the two seemingly contradictory characteristics of
+high electrical conductivity and large thermo-electric power. They are also
+potential hosts for other oxymoron-like functions. The known phases all contain
+one or two square-planar MO (M = Co, Bi, Pb, Tl, etc.) layers sandwiched
+together with AO (A = Ca, Sr, Ba, etc.) planes of square symmetry and CoO2
+layers of hexagonal symmetry. Here we report realization of the simplest (m =
+0) ML phase forming in the Sr-Co-O system with the cation ratio, Sr/Co = 1.
+Atomic-resolution TEM imaging confirms for the new phase the parent three-layer
+crystal structure, SrO-SrO-CoO2, which is compatible with the formula of
+[Sr2O2]qCoO2. Electron diffraction reveals that the phase is rather
+commensurate, i.e. the ""misfit parameter"" q is 0.5. Nevertheless, in terms of
+the transport-property characteristics the new ML parent is comparable to its
+earlier-established and more complex derivatives.",0511449v1
+2005-11-29,Enhanced thermopower in an intergrowth cobalt oxide Li$_{0.48}$Na$_{0.35}$CoO$_{2}$,"We report the measurements of thermopower, electrical resistivity and thermal
+conductivity in a complex cobalt oxide Li$_{0.48}$Na$_{0.35}$CoO$_{2}$, whose
+crystal structure can be viewed as an intergrowth of the O3 phase of
+Li$_{x}$CoO$_{2}$ and the P2 phase of Na$_{y}$CoO$_{2}$ along the c axis. The
+compound shows large room-temperature thermopower of $\sim$180 $\mu$V/K, which
+is substantially higher than those of Li$_{x}$CoO$_{2}$ and Na$_{y}$CoO$_{2}$.
+The figure of merit for the polycrystalline sample increases rapidly with
+increasing temperature, and it achieves nearly 10$^{-4}$ K$^{-1}$ at 300 K,
+suggesting that Li$_{x}$Na$_{y}$CoO$_{2}$ system is a promising candidate for
+thermoelectric applications.",0511691v1
+2005-12-02,Activation mechanisms in sodium-doped Silicon MOSFETs,"We have studied the temperature dependence of the conductivity of a silicon
+MOSFET containing sodium ions in the oxide above 20 K. We find the impurity
+band resulting from the presence of charges at the silicon-oxide interface is
+split into a lower and an upper band. We have observed activation of electrons
+from the upper band to the conduction band edge as well as from the lower to
+the upper band. A possible explanation implying the presence of Hubbard bands
+is given.",0512039v7
+2005-12-09,Comparison of the Electronic Structures of Two Non-cuprate Layered Transition Metal Oxide Superconductors,"Comparison is made of the electronic structure of the little-studied layered
+transition metal oxide LiNbO$_2$ with that of Na$_x$CoO$_2$, which has
+attracted tremendous interest since superconductivity was discovered in its
+hydrate. Although the active transition metal $d$ states are quite different
+due to different crystal fields and band filling, both systems show a strong
+change of electronic structure with changes in the distance between the
+transition metal ion layer and the oxygen layers. The niobate is unusual in
+having a large second-neighbor hopping amplitude, and a nearest neighbor
+hopping amplitude that is sensitive to the Nb-O separation. Li$_x$NbO$_2$ also
+presents the attractive simplicity of a single band triangular lattice system
+with variable carrier concentration that is superconducting.",0512211v2
+2005-12-10,Electron correlations and bond-length fluctuations in layered copper oxides: electron versus hole doping,"We investigate the nature of the electronic ground state and electron-lattice
+couplings for doped chains of CuO_4 plaquettes or CuO_6 octahedra. The undoped
+configuration implies here Cu 3d^9 and O 2p^6 formal valence states. The
+results of multiconfiguration calculations on 4-plaquette (or 4-octahedra)
+linear clusters indicate strong electron-lattice interactions and polaronic
+behavior of the doped particles, for both electron and hole doping. For certain
+phases of the oxygen-ion half-breathing distortions a multi-well energy
+landscape is predicted. Since each well is associated to carriers localized at
+different sites, the half-breathing displacements induce charge transfer along
+the chain. In the case of hole-doping, the trends found by ab initio
+multiconfiguration calculations on 4-octahedra clusters are confirmed by
+density-matrix renormalization-group calculations for a p-d, extended Hubbard
+model with chains of few tens of CuO_4 plaquettes. Under the assumption of
+charge separation and the formation of 1/3-doped stripes, our results seem to
+support the vibronic mechanism and the traveling charge-density wave scenario
+proposed in some recent contributions for superconductivity in copper oxides.",0512219v3
+2005-12-21,Full oxide heterostructure combining a high-Tc diluted ferromagnet with a high-mobility conductor,"We report on the growth of heterostructures composed of layers of the
+high-Curie temperature ferromagnet Co-doped (La,Sr)TiO3 (Co-LSTO) with
+high-mobility SrTiO3 (STO) substrates processed at low oxygen pressure. While
+perpendicular spin-dependent transport measurements in STO//Co-LSTO/LAO/Co
+tunnel junctions demonstrate the existence of a large spin polarization in
+Co-LSTO, planar magnetotransport experiments on STO//Co-LSTO samples evidence
+electronic mobilities as high as 10000 cm2/Vs at T = 10 K. At high enough
+applied fields and low enough temperatures (H < 60 kOe, T < 4 K) Shubnikov-de
+Haas oscillations are also observed. We present an extensive analysis of these
+quantum oscillations and relate them with the electronic properties of STO, for
+which we find large scattering rates up to ~ 10 ps. Thus, this work opens up
+the possibility to inject a spin-polarized current from a high-Curie
+temperature diluted oxide into an isostructural system with high-mobility and a
+large spin diffusion length.",0512533v1
+2006-01-17,Surface Reactivity and Quantum-Size effects on the Electronic Density Decay Length of ultrathin Metal Films,"The origin of the correlation between surface reactivity and quantum-size
+effects, observed in recent experiments on the oxidation of ultrathin magnesium
+films, is addressed by means of ab-initio calculations and model predictions.
+We show that the decay length in vacuum of the electronic local density of
+states at the Fermi energy exhibits systematic oscillations with film
+thickness, with local maxima induced when a quantum well state at k// = 0
+crosses the Fermi energy. The predicted changes in the decay length are
+expected to have a major impact on the electron transfer rate by tunneling,
+which has been proposed to control the initial sticking of O2 in the oxidation
+process.",0601364v1
+2006-02-21,Evidance for an Oxygen Diffusion Model for the Electric Pulse Induced Resistance Change Effect in Oxides,"Electric pulse induced resistance (EPIR) switching hysteresis loops for
+Pr0.7Ca0.7MnO3 (PCMO) perovskite oxide films were found to exhibit an
+additional sharp ""shuttle peak"" around the negative pulse maximum for films
+deposited in an oxygen deficient ambient. The device resistance hysteresis loop
+consists of stable high resistance and low resistance states, and transition
+regions between them. The resistance relaxation of the ""shuttle peak"" and its
+temperature behavior as well as the resistance relaxation in the transition
+regions were studied, and indicate that the resistance switching relates to
+oxygen diffusion with activation energy about 0.4eV. An oxygen diffusion model
+with the oxygen ions (vacancies) as the active agent is proposed for the
+non-volatile resistance switching effect in PCMO.",0602507v2
+2006-03-20,The role of oxygen vacancies in SrTiO3 at the LaAlO3/SrTiO3 interface,"Strontium titanate, SrTiO3, a widely used substrate material for electronic
+oxide thin film devices, has provided many interesting features. In a
+combination with a similar oxide material, LaAlO3, it has recently received
+great interest. It was suggested that two-dimensional electron gas is formed at
+the interface between SrTiO3 and LaAlO3, resulting in high electrical
+conductivity and mobility. In this report we demonstrate that the transport
+properties in those heterostructures are very sensitive to the deposition
+parameters during thin film growth. Using cathode- and photoluminescence
+studies in conjunction with measurements of electrical transport properties and
+microstructure we show that the electronic properties observed at a
+LaAlO3/SrTiO3 interface can be explained by oxygen reduced SrTiO3. In addition,
+we demonstrate that oxygen can be pushed in and out of the sample, but that
+re-oxygenation of an initially oxygen depleted LaAlO3/SrTiO3 heterostructure is
+partly prevented by the presence of the film.",0603501v1
+2006-03-24,Angle-resolved photoemission spectroscopy of perovskite-type transition-metal oxides and their analyses using tight-binding band structure,"Nowadays it has become feasible to perform angle-resolved photoemission
+spectroscopy (ARPES) measurements of transition-metal oxides with
+three-dimensional perovskite structures owing to the availability of
+high-quality single crystals of bulk and epitaxial thin films. In this article,
+we review recent experimental results and interpretation of ARPES data using
+empirical tight-binding band-structure calculations. Results are presented for
+SrVO$_3$ (SVO) bulk single crystals, and La$_{1-x}$Sr$_x$FeO$_3$ (LSFO) and
+La$_{1-x}$Sr$_x$MnO$_3$ (LSMO) thin films. In the case of SVO, from comparison
+of the experimental results with calculated surface electronic structure, we
+concluded that the obtained band dispersions reflect the bulk electronic
+structure. The experimental band structures of LSFO and LSMO were analyzed
+assuming the G-type antiferromagnetic state and the ferromagnetic state,
+respectively. We also demonstrated that the intrinsic uncertainty of the
+electron momentum perpendicular to the crystal surface is important for the
+interpretation of the ARPES results of three-dimensional materials.",0603642v1
+2006-04-28,Carrier concentration dependence of optical Kerr nonlinearity in indium tin oxide films,"Optical Kerr nonlinearity (n2) in n-type indium tin oxide (ITO) films coated
+on glass substrates has been measured using Z-scans with 200-fs laser pulses at
+wavelengths ranging from 720 to 780 nm. The magnitudes of the measured
+nonlinearity in the ITO films were found to be dependent on the carrier
+concentration with a maximum n2-value of 4.1 x 10-5 cm2/GW at 720-nm wavelength
+and an electron density of Nd = 5.8 x 1020 cm-3. The Kerr nonlinearity was also
+observed to be varied with the laser wavelength. By employing a femtosecond
+time-resolved optical Kerr effect (OKE) technique, the relaxation time of OKE
+in the ITO films is determined to be ~1 ps. These findings suggest that the
+Kerr nonlinearity in ITO can be tailored by controlling the carrier
+concentration, which should be highly desirable in optoelectronic devices for
+ultrafast all-optical switching.",0604652v1
+2006-05-24,Morphological and Structural Characterization of Cro2/Cr2o3 Films Grown by Laser-CVD,"This work reports on the synthesis of chromium (III, IV) oxides films by KrF
+laser-assisted CVD. Films were deposited onto sapphire substrates at room
+temperature by photodissociation of Cr(CO)6 in dynamic atmospheres containing
+oxygen and argon. A study of the processing parameters has shown that partial
+pressure ratio of O2 to Cr(CO)6 and laser fluence are the prominent parameters
+that have to be accurately controlled in order to co-deposit both crystalline
+oxide phases. Films consistent with such a two-phase system were synthesised
+for a laser fluence of 75 mJ cm-2 and a partial pressure ratio about 1.
+  PACS: 81.15.Fg, 81.15.Kk, 81.05.Je",0605592v1
+2006-06-15,Angle-resolved photoemission study of cobalt oxide superconductor NaxCoO2.yH2O : Observation of the Fermi surface,"Cobalt oxide superconductor NaxCoO2.yH2O is studied by angle-resolved
+photoemission spectroscopy (ARPES). We report the Fermi surface (FS) topology
+and electronic structure near the Fermi level (EF) of NaxCoO2.yH2O. Our result
+indicates the presence of the hexagonal FS centered at G point, while the small
+pocket FSs along G-K direction are absent similar to NaxCoO2. The top of the
+eg' band, which is expected in band calculations to form the small pocket FSs,
+extends to within 20 - 50 meV below EF, more closer to EF than in NaxCoO2. We
+discuss its possible role in superconductivity, comparing with other
+experimental and theoretical results.",0606424v1
+2006-07-03,"Electronic structures of layered perovskite Sr2MO4 (M=Ru, Rh, and Ir)","We investigated the electronic structures of the two-dimensional layered
+perovskite Sr$_{2}$\textit{M}O$_{4}$ (\textit{M}=4\textit{d} Ru, 4\textit{d}
+Rh, and 5\textit{d} Ir) using optical spectroscopy and polarization-dependent O
+1\textit{s} x-ray absorption spectroscopy. While the ground states of the
+series of compounds are rather different, their optical conductivity spectra
+$\sigma(\omega)$ exhibit similar interband transitions, indicative of the
+common electronic structures of the 4\textit{d} and 5\textit{d} layered oxides.
+The energy splittings between the two $e_{g}$ orbitals, $i.e.$,
+$d_{3z^{2}-r^{2}}$ and $d_{x^{2}-y^{2}}$, are about 2 eV, which is much larger
+than those in the pseudocubic and 3\textit{d} layered perovskite oxides. The
+electronic properties of the Sr$_{2}$\textit{M}O$_{4}$ compounds are discussed
+in terms of the crystal structure and the extended character of the 4\textit{d}
+and 5\textit{d} orbitals.",0607026v2
+2006-07-07,Uniaxial to unidirectional transition of perpendicular interlayer coupling in IrMn/CoFe/NiFeO/CoFe quadrilayers,"We studied the interlayer coupling in the quadrilayer consisting of IrMn/CoFe
+(bottom layer)/NiFeOx/ CoFe (top layer). The in-plane perpendicular interlayer
+coupling is observed between CoFe layers at room temperature. An anisotropy
+transition from uniaxial to unidirectional in the perpendicular direction is
+observed around Tt = 55 K. The nano-oxide layer NiFeOx shows no distinguishable
+ferromagnetic signal in the high-temperature (uniaxial) phase, while a strong
+signal appeared in the low-temperature (unidirectional) phase. A possible
+two-component scenario, that the nano-oxide layer may contain both amorphous
+short-range antiferromagnetic domains and superparamagneitc clusters, is
+proposed to explain the phase transition.",0607199v1
+2006-08-08,Stable Oxide Nanoparticle Clusters Obtained by Complexation,"We report on the electrostatic complexation between polyelectrolyte-neutral
+copolymers and oppositely charged 6 nm-crystalline nanoparticles. For two
+different dispersions of oxide nanoparticles, the electrostatic complexation
+gives rise to the formation of stable nanoparticle clusters in the range 20 -
+100 nm. It is found that inside the clusters, the particles are pasted together
+by the polyelectrolyte blocks adsorbed on their surface. Cryo-transmission
+electronic microscopy allows to visualize the clusters and to determine the
+probability distributions functions in size and in aggregation number. The
+comparison between light scattering and cryo-microscopy results suggests the
+existence of a polymer brush around the clusters.",0608189v1
+2006-09-28,The Effect of Counterions on the Interactions of Charged Oligothiophenes,"The functionality of conjugated polymer systems often relies on oxidations or
+reductions, in most cases mediated by the presence of counterions. The effect
+that the common counterion hexafluorophosphate (PF6-) has on the intermolecular
+interactions between charged oligothiophenes is investigated here using ab
+initio quantum chemistry methods. Counterions are explicitly included in the
+simulations of oxidized oligothiophenes and in the dimerization process. Our
+calculations provide quantitative and qualitative insight into the
+intermolecular interactions in oligothiophene-counterion systems and show that
+the intermolecular pi-stacking of oligothiophenes is not adversely affected by
+the presence of counterions, and that in fact oligothiophene dimerization is
+further stabilized by their presence.",0609722v1
+2006-10-06,Resistive hystersis effects in perovskite oxide-based heterostructure junctions,"In this paper, we report the electrical and structural properties of the
+oxide-based metal/ferroelectric/metal (MFM) junctions. The heterostructures are
+composed of ultrathin layers of La0.7Ca0.3MnO3 (LCMO) as a metallic layer and,
+BaTiO3 (BTO) as a ferroelectric layer. Junction based devices, having the
+dimensions of 400 x 200 micom2, have been fabricated upon LCMO/BTO/LCMO
+heterostructures by photolithography and Ar-ion milling technique. The DC
+current-voltage (I-V) characteristics of the MFM junctions were carried out. At
+300 K, the devices showed the linear (I-V) characteristics, whereas at 77 K,
+(I-V) curves exhibited some reproducible switching behaviours with well-defined
+remnant currents. The resulting resistance modulation is very different from
+what was already reported in ultrathin ferroelectric layers displaying
+resistive switching. A model is presented to explain the datas",0610172v1
+2006-10-12,Effect of the Fe substitution in Ti-Ni shape memory alloys,"Shape memory Ti-Ni alloys attracted much attention in the recent years, since
+they are shape memory, intelligent as well as functional materials. In the
+present investigation Ti51Ni49 and Ti51Ni45Fe4 alloys were synthesized through
+radio frequency (RF) induction melting. The alloy was characterized through
+x-ray diffraction (XRD), scanning electron microscopy (SEM), Mossbauer
+spectroscopy (MS) and positron annihilation techniques (PAT).The Fe
+substitution stabilized the TiNi type cubic (a=2.998 A) phase. The surface
+microstructure and presence of the oxide layer in Ti51Ni45Fe4 alloy have been
+investigated by SEM. The Positron annihilation measurements indicated a similar
+bulk electron density in both the as-cast and annealed (1000 0 C for 30 hrs)
+alloys, typically like that of bulk Ti. Mossbauer spectroscopy studies of
+as-cast and annealed iron substituted samples showed regions in the samples
+where nuclear Zeeman splitting of Fe levels occurred and an oxide phase was
+found to be present in as cast Ti51Ni45Fe4 alloy, while annealed sample
+indicated the presence of bcc iron phase .",0610340v1
+2007-03-09,Weak coupling Bardeen-Cooper-Schrieffer suerconductivity in the Electron-Doped Cuprate Superconductors,"We use in-plane tunneling spectroscopy to study the temperature dependence of
+the local superconducting gap $\Delta(T)$ in electron-doped copper oxides with
+various $T_c$'s and Ce-doping concentrations. We show that the temperature
+dependence of $\Delta(T)$ follows the expectation of the
+Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity, where
+$\Delta(0)/k_{B}T_{c}\approx1.72\pm 0.15$ and $\Delta(0)$ is the average
+superconducting gap across the Fermi surface, for all the doping levels
+investigated. These results suggest that the electron-doped superconducting
+copper oxides are weak coupling BCS superconductors.",0703256v2
+2007-03-19,Band-to-band tunneling in a carbon nanotube metal-oxide-semiconductor field-effect transistor is dominated by phonon assisted tunneling,"Band-to-band tunneling (BTBT) devices have recently gained a lot of interest
+due to their potential for reducing power dissipation in integrated circuits.
+We have performed extensive simulations for the BTBT operation of carbon
+nanotube metal-oxide-semiconductor field-effect transistors (CNT-MOSFETs) using
+the non-equilibrium Green's functions formalism for both ballistic and
+dissipative quantum transport. In comparison with recently reported
+experimental data (Y. Lu et al, J. Am. Chem. Soc., v. 128, p. 3518-3519, 2006),
+we have obtained strong evidence that BTBT in CNT-MOSFETs is dominated by
+optical phonon assisted inelastic transport, which can have important
+implications on the transistor characteristics. It is shown that under large
+biasing conditions two-phonon scattering may also become important.",0703493v1
+1997-03-02,Towards a Field Theory of F-theory,"We make a proposal for a bosonic field theory in twelve dimensions that
+admits the bosonic sector of eleven-dimensional supergravity as a consistent
+truncation. It can also be consistently truncated to a ten-dimensional
+Lagrangian that contains all the BPS p-brane solitons of the type IIB theory.
+The mechanism allowing the consistent truncation in the latter case is unusual,
+in that additional fields with an off-diagonal kinetic term are non-vanishing
+and yet do not contribute to the dynamics of the ten-dimensional theory. They
+do, however, influence the oxidation of solutions back to twelve dimensions. We
+present a discussion of the oxidations of all the basic BPS solitons of
+M-theory and the type IIB string to D=12. In particular, the NS-NS and R-R
+strings of the type IIB theory arise as the wrappings of membranes in D=12
+around one or other circle of the compactifying 2-torus.",9703012v2
+1997-10-20,Interacting Intersections,"Intersecting p-branes can be viewed as higher-dimensional interpretations of
+multi-charge extremal p-branes, where some of the individual p-branes undergo
+diagonal dimensional oxidation, while the others oxidise vertically. Although
+the naive vertical oxidation of a single p-brane gives a continuum of p-branes,
+a more natural description arises if one considers a periodic array of p-branes
+in the higher dimension, implying a dependence on the compactification
+coordinates. This still reduces to the single lower-dimensional p-brane when
+viewed at distances large compared with the period. Applying the same logic to
+the multi-charge solutions, we are led to consider more general classes of
+intersecting p-brane solutions, again depending on the compactification
+coordinates, which turn out to be described by interacting functions rather
+than independent harmonic functions. These new solutions also provide a more
+satisfactory interpretation for the lower-dimensional multi-charge p-branes,
+which otherwise appear to be nothing more than the improbable coincidence of
+charge-centres of individual constituents with zero binding energy.",9710155v2
+2002-06-21,"On d=4,5,6 Vacua with 8 Supercharges","We show how all known N=2, d=4,5,6 maximally supersymmetric vacua (Hpp-waves
+and aDSxS solutions) are related through dimensional reduction/oxidation
+preserving all the unbroken supersymmetries. In particular we show how the N=2,
+d=5 family of vacua (which are the near-horizon geometry of supersymmetric
+rotating black holes) interpolates between aDS_2xS^3 and aDS_3xS^2 in parameter
+space and how it can be dimensionally reduced to an N=2, d=4 dyonic
+Robinson-Bertotti solution with geometry aDS_2xS^2 and oxidized to an N=2, d=6
+solution with aDS_3xS^3 geometry (which is the near-horizon of the self-dual
+string).",0206200v3
+2002-10-18,The group theory of oxidation,"Dimensional reduction of (super-)gravity theories to 3 dimensions results in
+sigma models on coset spaces G/H, such as the E_8/SO(16) coset in the bosonic
+sector of 3 dimensional maximal supergravity. The reverse process, oxidation,
+is the reconstruction of a higher dimensional gravity theory from a coset sigma
+model. Using the group G as starting point, the higher dimensional models
+follow essentially from decomposition into subgroups. All equations of motion
+and Bianchi identities can be directly reconstructed from the group lattice,
+Kaluza-Klein modifications and Chern-Simons terms are encoded in the group
+structure. Manipulations of extended Dynkin diagrams encode matter content, and
+(string) dualities. The reflection symmetry of the ``magic triangle'' for E_n
+gravities, and approximate reflection symmetry of the older ``magic triangle''
+of supergravities in 4 dimensions, are easily understood in this framework.",0210178v3
+2004-09-27,"Chemistry of Chern-Simons Supergravity: reduction to a BPS kink, oxidation to M-theory and thermodynamical aspects","We construct a supersymmetric extension of the two dimensional
+Kaluza-Klein-reduced gravitational Chern-Simons term, and globally study its
+solutions, labelled by mass and U(1) charge c. The kink solution is BPS, and in
+an appropriate conformal frame all solutions asymptotically approach AdS. The
+thermodynamics of the Hawking effect yields interesting behavior for the
+specific heat and hints at a Hawking-Page-like transition at T_{critical} \sim
+c^{3/2}. We address implications for higher dimensions (""oxidation""), in
+particular D=3,4 and 11, and comment briefly on AdS/CFT aspects of the kink.",0409273v2
+2002-01-14,Statistical Analysis of a Semilinear Hyperbolic System Advected by a White in Time Random Velocity Field,"We study a system of semilinear hyperbolic equations passively advected by
+smooth white noise in time random velocity fields. Such a system arises in
+modeling non-premixed isothermal turbulent flames under single-step kinetics of
+fuel and oxidizer. We derive closed equations for one-point and multi-point
+probability distribution functions (PDFs) and closed form analytical formulas
+for the one point PDF function, as well as the two-point PDF function under
+homogeneity and isotropy. Exact solution formulas allows us to analyze the
+ensemble averaged fuel/oxidizer concentrations and the motion of their level
+curves. We recover the empirical formulas of combustion in the thin reaction
+zone limit and show that these approximate formulas can either underestimate or
+overestimate average concentrations when reaction zone is not tending to zero.
+We show that the averaged reaction rate slows down locally in space due to
+random advection induced diffusion; and that the level curves of ensemble
+averaged concentration undergo diffusion about mean locations.",0201024v1
+2006-10-26,Front explosion in a periodically forced surface reaction,"Resonantly-forced oscillatory reaction-diffusion systems can exhibit fronts
+with complicated interfacial structure separating phase-locked homogeneous
+states. For values of the forcing amplitude below a critical value the front
+""explodes"" and the width of the interfacial zone grows without bound. Such
+front explosion phenomena are investigated for a realistic model of catalytic
+CO oxidation on a Pt(110) surface in the 2:1 and 3:1 resonantly-forced regimes.
+In the 2:1 regime, the fronts are stationary and the front explosion leads to a
+defect-mediated turbulent state. In the 3:1 resonantly-forced system, the
+fronts propagate. The front velocity tends to zero as the front explosion point
+is reached and the final asymptotic state is a 2:1 resonantly-locked
+labyrinthine pattern. The front dynamics described here should be observable in
+experiment since the model has been shown to capture essential features of the
+CO oxidation reaction.",0610064v1
+2002-08-26,A radium assay technique using hydrous titanium oxide adsorbent for the Sudbury Neutrino Observatory,"As photodisintegration of deuterons mimics the disintegration of deuterons by
+neutrinos, the accurate measurement of the radioactivity from thorium and
+uranium decay chains in the heavy water in the Sudbury Neutrino Observatory
+(SNO) is essential for the determination of the total solar neutrino flux. A
+radium assay technique of the required sensitivity is described that uses
+hydrous titanium oxide adsorbent on a filtration membrane together with a
+beta-alpha delayed coincidence counting system. For a 200 tonne assay the
+detection limit for 232Th is a concentration of 3 x 10^(-16) g Th/g water and
+for 238U of 3 x 10^(-16) g U/g water. Results of assays of both the heavy and
+light water carried out during the first two years of data collection of SNO
+are presented.",0208015v1
+2000-11-30,Modelling horizontal and vertical concentration profiles of ozone and oxides of nitrogen within high-latitude urban area,"A Lagrangian column model has been developed to simulate the mean (monthly
+and annual) three-dimensional structure in ozone and nitrogen oxides
+concentrations in the boundary layer within and immediately around an urban
+area. Short time-scale photochemical processes of ozone, as well as emissions
+and deposition to the ground are simulated. The results show that the average
+surface ozone concentration in the urban area is lower than the surrounding
+rural areas by typically 50%. Model results are compared with observations.",0011074v2
+2003-11-24,Laser ablation synthesis of zinc oxide clusters: a new family of fullerenes?,"Positively charged zinc oxide clusters ZnnOm (up to n = 16, m <= n) of
+various stoichiometry were synthesized in the gas phase by excimer ArF laser
+ablation of a ZnO target and investigated using time-of-flight mass
+spectrometry. Depending on ablation conditions, either metal rich or
+stoichiometric clusters dominate in the mass spectrum. When the irradiated
+target surface is fairly fresh, the most abundant clusters are metal rich with
+Zn(n+1)On and Zn(n+3)On being the major series. The stoichiometric clusters are
+observed with an etched ablated surface. The magic numbers at n = 9, 11 and 15
+in mass spectra of (ZnO)n clusters indicate that the clusters have hollow
+spheroid structures related to fullerenes. A local abundance minimum at n = 13
+provides an additional evidence for the presence in the ablation plume of
+fullerene-like (ZnO)n clusters.",0311117v1
+2006-03-13,Experimental and modeling study of the oxidation of xylenes,"This paper describes an experimental and modeling study of the oxidation of
+the three isomers of xylene (ortho-, meta- and para-xylenes). For each
+compound, ignition delay times of hydrocarbon-oxygen-argon mixtures with fuel
+equivalence ratios from 0.5 to 2 were measured behind reflected shock waves for
+temperatures from 1330 to 1800 K and pressures from 6.7 to 9 bar. The results
+show a similar reactivity for the three isomers. A detailed kinetic mechanism
+has been proposed, which reproduces our experimental results, as well as some
+literature data obtained in a plug flow reactor at 1155 K showing a clear
+difference of reactivity between the three isomers of xylene. The main reaction
+paths have been determined by sensitivity and flux analyses and have allowed
+the differences of reactivity to be explained.",0603102v1
+2006-04-24,Mathematical model for blood flow autoregulation by endothelium-derived relaxing factor,"The fluid shear stress is an important regulator of the cardiovascular system
+via the endothelium-derived relaxing factor (EDRF) that is Nitric Oxide. This
+mechanism involves biochemical reactions in an arterial wall. The
+autoregulation process is managed by the vascular tonus and gives the negative
+feedback for the shear stress changing. A new mathematical model for the
+autoregulation of a blood flow through arteria under the constant transmural
+pressure is presented. Endothelium-derived relaxing factor Nitric Oxide, the
+multi-layer structure of an arterial wall, and kinetic-diffusion processes are
+taken into consideration. The limit case of the thin-wall artery is
+analytically studied. The stability condition for a stationary point of the
+linearized system is given. The exact stationary solutions of the origin system
+are found. The numerical simulation for the autoregulation system is presented.
+It is shown the arteria adaptation to an initial radial perturbation and the
+transition of the system to new equilibrium state in response on the blood flow
+changing.",0604192v1
+2005-03-17,Globally controlled artificial semiconducting molecules as quantum computers,"Quantum computers are expected to be considerably more efficient than
+classical computers for the execution of some specific tasks. The difficulty in
+the practical implementation of thoose computers is to build a microscopic
+quantum system that can be controlled at a larger mesoscopic scale. Here I show
+that vertical lines of donor atoms embedded in an appropriate Zinc Oxide
+semiconductor structure can constitute artificial molecules that are as many
+copy of the same quantum computer. In this scalable architecture, each unit of
+information is encoded onto the electronic spin of a donor. Contrary to most
+existing practical proposals, here the logical operations only require a global
+control of the spins by electromagnetic pulses. Ensemble measurements simplify
+the readout. With appropriate improvement of its growth and doping methods,
+Zinc Oxide could be a good semiconductor for the next generation of computers.",0503161v1
+2007-04-01,Aspects of Electron-Phonon Self-Energy Revealed from Angle-Resolved Photoemission Spectroscopy,"Lattice contribution to the electronic self-energy in complex correlated
+oxides is a fascinating subject that has lately stimulated lively discussions.
+Expectations of electron-phonon self-energy effects for simpler materials, such
+as Pd and Al, have resulted in several misconceptions in strongly correlated
+oxides. Here we analyze a number of arguments claiming that phonons cannot be
+the origin of certain self-energy effects seen in high-$T_c$ cuprate
+superconductors via angle resolved photoemission experiments (ARPES), including
+the temperature dependence, doping dependence of the renormalization effects,
+the inter-band scattering in the bilayer systems, and impurity substitution. We
+show that in light of experimental evidences and detailed simulations, these
+arguments are not well founded.",0704.0093v1
+2007-04-12,Extremely strong-coupling superconductivity and anomalous lattice properties in the beta-pyrochlore oxide KOs2O6,"Superconducting and normal-state properties of the beta-pyrochlore oxide
+KOs2O6 are studied by means of thermodynamic and transport measurements. It is
+shown that the superconductivity is of conventional s-wave type and lies in the
+extremely strong-coupling regime. Specific heat and resistivity measurements
+reveal that there are characteristic low-energy phonons that give rise to
+unusual scattering of carriers due to strong electron-phonon interactions. The
+entity of the low-energy phonons is ascribed to the heavy rattling of the K ion
+confined in an oversized cage made of OsO6 octahedra. It is suggested that this
+electron-rattler coupling mediates the Cooper pairing, resulting in the
+extremely strong-coupling superconductivity.",0704.1528v1
+2007-04-19,"High Mobility in LaAlO3/SrTiO3 Heterostructures: Origin, Dimensionality and Perspectives","We have investigated the dimensionality and origin of the magnetotransport
+properties of LaAlO3 films epitaxially grown on TiO2-terminated SrTiO3(001)
+substrates. High mobility conduction is observed at low deposition oxygen
+pressures (PO2 < 10^-5 mbar) and has a three-dimensional character. However, at
+higher PO2 the conduction is dramatically suppressed and nonmetallic behavior
+appears. Experimental data strongly support an interpretation of these
+properties based on the creation of oxygen vacancies in the SrTiO3 substrates
+during the growth of the LaAlO3 layer. When grown on SrTiO3 substrates at low
+PO2, other oxides generate the same high mobility as LaAlO3 films. This opens
+interesting prospects for all-oxide electronics.",0704.2523v1
+2007-05-31,Simple approach for high-contrast optical imaging and characterization of graphene-based sheets,"A simple optical method is presented for identifying and measuring the
+effective optical properties of nanometer-thick, graphene-based materials,
+based on the use of substrates consisting of a thin dielectric layer on
+silicon. High contrast between the graphene-based materials and the substrate
+is obtained by choosing appropriate optical properties and thickness of the
+dielectric layer. The effective refractive index and optical absorption
+coefficient of graphene oxide, thermally reduced graphene oxide, and graphene
+are obtained by comparing the predicted and measured contrasts.",0706.0029v2
+2007-06-14,Modelling of the gas-phase oxidation of cyclohexane,"This paper presents a modeling study of the oxidation of cyclohexane from low
+to intermediate temperature (650-1050 K), including the negative temperature
+coefficient (NTC) zone. A detailed kinetic mechanism has been developed using
+computer-aided generation. This comprehensive low-temperature mechanism
+involves 513 species and 2446 reactions and includes two additions of
+cyclohexyl radicals to oxygen, as well as subsequent reactions. The rate
+constants of the reactions involving the formation of bicyclic species
+(isomerizations, formation of cyclic ethers) have been evaluated from
+literature data. This mechanism is able to satisfactorily reproduce
+experimental results obtained in a rapid-compression machine for temperatures
+ranging from 650 to 900 K and in a jet-stirred reactor from 750 to 1050 K.
+Flow-rate analyses have been performed at low and intermediate temperatures.",0706.2064v1
+2007-07-16,Quantum critical behaviour in the superfluid density of strongly underdoped ultrathin cuprate films,"A central issue in the physics of high temperature superconductors is to
+understand superconductivity within a single copper-oxide layer or bilayer, the
+fundamental structural unit in the cuprates, and how it is lost with
+underdoping. As mobile holes are removed from the CuO_2 planes, the transition
+temperature T_C and superfluid density n_S decrease in a surprisingly
+correlated fashion in crystals and thick films. We seek to elucidate the
+intrinsic physics of bilayers in the strongly underdoped regime, near the
+critical doping level where superconductivity disappears. We report
+measurements of n_S(T) in films of Y_{1-x}Ca_xBa_2Cu_3O_{7-\delta} as thin as
+two copper-oxide bilayers with T_C's as low as 3 K. In addition to seeing the
+two-dimensional (2D) Kosterlitz-Thouless-Berezinski transition at T_C, we
+observe a remarkable scaling of T_C with n_S(0) that demonstrates that the
+disappearance of superconductivity with underdoping is due to quantum
+fluctuations near a T = 0 2D quantum critical point.",0707.2397v1
+2007-07-20,A canonical transformation theory from extended normal ordering,"The Canonical Transformation theory of Yanai and Chan [J. Chem. Phys. 124,
+194106 (2006)] provides a rigorously size-extensive description of dynamical
+correlation in multireference problems. Here we describe a new formulation of
+the theory based on the extended normal ordering procedure of Mukherjee and
+Kutzelnigg [J. Chem. Phys. 107, 432 (1997)].
+  On studies of the water, nitrogen, and iron-oxide potential energy curves,
+the Linearised Canonical Transformation Singles and Doubles theory is
+competitive in accuracy with some of the best multireference methods, such as
+the Multireference Averaged Coupled Pair Functional, while computational
+timings (in the case of the iron-oxide molecule) are two-three orders of
+magnitude faster and comparable to those of Complete Active Space Second-Order
+Perturbation Theory. The results presented here are greatly improved both in
+accuracy and in cost over our earlier study as the result of a new numerical
+algorithm for solving the amplitude equations.",0707.3128v1
+2007-09-12,Ferroelectricity in artificial bicolor oxide superlattices,"We report on the growth and properties of high quality bicolor oxide
+superlattices, composed of two perovskites out of BaTiO3, CaTiO3, and SrTiO3.
+The artificially grown superlattices are structurally unique and have a
+macroscopically homogeneous phase, which is not feasible to recreate in bulk
+form. By artificial structuring, it is found that the polarization of such
+superlattices can be highly increased as compared to pseudo-binary ceramics
+with the same overall composition. Such strong enhancement in superlattice is
+attributed to newly-developed ionic motions of A-site cations at the
+hetero-interfaces due to the interfacial coupling of electrostatic and elastic
+interactions, which cannot be found in single phase materials.",0709.1791v1
+2007-10-07,Mapping the Spatial Distribution of Charge Carriers in LaAlO3/SrTiO3 Heterostructures,"At the interface between complex insulating oxides, novel phases with
+interesting properties may occur, such as the metallic state reported in the
+LaAlO3/SrTiO3 system. While this state has been predicted and reported to be
+confined at the interface, some works indicate a much broader spatial
+extension, thereby questioning its origin. Here we provide for the first time a
+direct determination of the carrier density profile of this system through
+resistance profile mappings collected in cross-section LaAlO3/SrTiO3 samples
+with a conducting-tip atomic force microscope (CT-AFM). We find that, depending
+upon specific growth protocols, the spatial extension of the high-mobility
+electron gas can be varied from hundreds of microns into SrTiO3 to a few
+nanometers next to the LaAlO3/SrTiO3 interface. Our results emphasize the
+potential of CT-AFM as a novel tool to characterize complex oxide interfaces
+and provide us with a definitive and conclusive way to reconcile the body of
+experimental data in this system.",0710.1395v2
+2007-10-25,Circuit-Level Modeling for Concurrent Testing of Operational Defects due to Gate Oxide Breakdown,"As device sizes shrink and current densities increase, the probability of
+device failures due to gate oxide breakdown (OBD) also increases. To provide
+designs that are tolerant to such failures, we must investigate and understand
+the manifestations of this physical phenomenon at the circuit and system level.
+In this paper, we develop a model for operational OBD defects, and we explore
+how to test for faults due to OBD. For a NAND gate, we derive the necessary
+input conditions that excite and detect errors due to OBD defects at the gate
+level. We show that traditional pattern generators fail to exercise all of
+these defects. Finally, we show that these test patterns can be propagated and
+justified for a combinational circuit in a manner similar to traditional ATPG.",0710.4715v1
+2007-11-12,Hyper-Raman scattering analysis of the vibrations in vitreous boron oxide,"Hyper-Raman scattering has been measured on vitreous boron oxide,
+$v-$B$_2$O$_3$. This spectroscopy, complemented with Raman scattering and
+infrared absorption, reveals the full set of vibrations that can be observed
+with light. A mode analysis is performed based on the local D$_{3h}$ symmetry
+of BO$_3$ triangles and B$_3$O$_3$ boroxol rings. The results show that in
+$v-$B$_2$O$_3$ the main spectral components can be succesfully assigned using
+this relatively simple model. In particular, it can be shown that the
+hyper-Raman boson peak arises from external modes that correspond mainly to
+librational motions of rigid boroxol rings.",0711.1782v1
+2007-12-11,Lattice instabilities in cubic pyrochlore Bi$_2$Ti$_2$O$_7$,"The oxide pyrochlore Bi$_2$Ti$_2$O$_7$ is in some ways analogous to
+perovskite PbTiO$_3$, in that Bi$_2$Ti$_2$O$_7$ has two cations, Bi$^{3+}$ and
+Ti$^{4+}$ in oxidation states that are normally associated with a propensity to
+off-center. However, unlike PbTiO$_3$, Bi$_2$Ti$_2$O$_7$ is experimentally
+observed to remain cubic down to 2 K, while the only observed ionic
+displacements are local and incoherent. Here we report first-principles
+calculations of the zone-center phonons of the ordered cubic pyrochlore which
+reveal several lattice instabilities. An analysis of the structural energetics
+suggest that the ordered cubic pyrochlore is unstable with respect to
+distortion towards a ferroelectric ground state with a large polarization. Our
+results suggest a key role of a frustrated soft polar mode in the dielectric
+properties of bismuth pyrochlores.",0712.1846v1
+2007-12-14,Optical conductivity and the correlation strength of high temperature copper-oxide superconductors,"High temperature copper-oxide-based superconductivity is obtained by adding
+carriers to insulating ""parent compounds"". It is widely believed the parent
+compounds are ""Mott"" insulators, in which the lack of conduction arises from
+anomalously strong electron-electron repulsion, and that the unusual properties
+of Mott insulators are responsible for high temperature superconductivity. This
+paper presents a comparison of optical conductivity measurements and
+theoretical calculations which challenges this belief. The analysis indicates
+that the correlation strength in the cuprates is not as strong as previously
+believed, that the materials are not properly regarded as Mott insulators, that
+antiferromagnetism is essential to obtain the insulating state and, by
+implication, that antiferromagnetism is essential to the properties of the
+doped metallic and superconducting state as well.",0712.2392v1
+2007-12-18,Effect of Edge Roughness on Electronic Transport in Graphene Nanoribbon Channel Metal Oxide Semiconductor Field-Effect Transistors,"Results of quantum mechanical simulations of the influence of edge disorder
+on transport in graphene nanoribbon metal oxide semiconductor field-effect
+transistors (MOSFETs) are reported. The addition of edge disorder significantly
+reduces ON-state currents and increases OFF-state currents, and introduces wide
+variability across devices. These effects decrease as ribbon widths increase
+and as edges become smoother. However the bandgap decreases with increasing
+width, thereby increasing the band-to-band tunneling mediated subthreshold
+leakage current even with perfect nanoribbons. These results suggest that
+without atomically precise edge control during fabrication, MOSFET performance
+gains through use of graphene will be difficult to achieve.",0712.3068v1
+2007-12-21,First-principles LDA+U and GGA+U study of plutonium oxides,"The electronic structure and properties of PuO$_{2}$ and Pu$_{2}$O$_{3}$ have
+been studied from first principles by the all-electron projector-augmented-wave
+(PAW) method. The local density approximation (LDA)+$U$ and the generalized
+gradient approximation (GGA)+$U$ formalism have been used to account for the
+strong on-site Coulomb repulsion among the localized Pu $5f$ electrons. We
+discuss how the properties of PuO$_{2}$ and Pu$_{2}$O$_{3}$ are affected by the
+choice of $U$ as well as the choice of exchange-correlation potential. Also,
+oxidation reaction of Pu$_{2}$O$_{3}$, leading to formation of PuO$_{2}$, and
+its dependence on $U$ and exchange-correlation potential have been studied. Our
+results show that by choosing an appropriate $U$ it is promising to correctly
+and consistently describe structural, electronic, and thermodynamic properties
+of PuO$_{2}$ and Pu$_{2}$O$_{3}$, which enables it possible the modeling of
+redox process involving Pu-based materials.",0712.3623v1
+2008-02-21,Enhanced Sensing Characteristics in MEMS-based Formaldehyde Gas Sensor,"This study has successfully demonstrated a novel self-heating formaldehyde
+gas sensor based on a thin film of NiO sensing layer. A new fabrication process
+has been developed in which the Pt micro heater and electrodes are deposited
+directly on the substrate and the NiO thin film is deposited above on the micro
+heater to serve as sensing layer. Pt electrodes are formed below the sensing
+layer to measure the electrical conductivity changes caused by formaldehyde
+oxidation at the oxide surface. Furthermore, the upper sensing layer and
+NiO/Al2O3 co-sputtering significantly increases the sensitivity of the gas
+sensor, improves its detection limit capability. The microfabricated
+formaldehyde gas sensor presented in this study is suitable not only for
+industrial process monitoring, but also for the detection of formaldehyde
+concentrations in buildings in order to safeguard human health.",0802.3072v1
+2008-02-22,Recent advances in pulsed-laser deposition of complex-oxides,"Pulsed-laser deposition (PLD) is one of the most promising techniques for the
+formation of complex-oxide heterostructures, superlattices, and well-controlled
+interfaces. The first part of this paper presents a review of several useful
+modifications of the process, including methods inspired by combinatorial
+approaches. We then discuss detailed growth kinetics results, which illustrate
+that 'true' layer-by-layer (LBL) growth can only be approached, but not fully
+met, even though many characterization techniques reveal interfaces with
+unexpected sharpness. Time-resolved surface x-ray diffraction measurements show
+that crystallization and the majority of interlayer mass transport occur on
+time scales that are comparable to those of the plume/substrate interaction,
+providing direct experimental evidence that a growth regime exists in which
+non-thermal processes dominate PLD. This understanding shows how kinetic growth
+manipulation can bring PLD closer to ideal LBL than any other growth method
+available today.",0802.3386v1
+2008-03-12,A Nexafs Study of Nitric Oxide Layers Adsorbed from a nitrite Solution onto a Pt(111) Surface,"NO molecules adsorbed on a Pt(111) surface from dipping in an acidic nitrite
+solution are studied by near edge X-ray absorption fine structure spectroscopy
+(NEXAFS), X-ray photoelectron spectroscopy (XPS), low energy electron
+diffraction (LEED) and scanning tunnelling microscopy (STM) techniques. LEED
+patterns and STM images show that no long range ordered structures are formed
+after NO adsorption on a Pt(111) surface. Although the total NO coverage is
+very low, spectroscopic features in N K-edge and O K-edge absorption spectra
+have been singled out and related to the different species induced by this
+preparation method. From these measurements it is concluded that the NO
+molecule is adsorbed trough the N atom in an upright conformation. The maximum
+saturation coverage is about 0.3 monolayers, and although nitric oxide is the
+major component, nitrite and nitrogen species are slightly co-adsorbed on the
+surface. The results obtained from this study are compared with those
+previously reported in the literature for NO adsorbed on Pt(111) under UHV
+conditions.",0803.1789v1
+2008-03-19,Electrodynamics of the vanadium oxides VO2 and V2O3,"The optical/infrared properties of films of vanadium dioxide (VO2) and
+vanadium sesquioxide (V2O3) have been investigated via ellipsometry and
+near-normal incidence reflectance measurements from far infrared to ultraviolet
+frequencies. Significant changes occur in the optical conductivity of both VO2
+and V2O3 across the metal-insulator transitions at least up to (and possibly
+beyond) 6 eV. We argue that such changes in optical conductivity and electronic
+spectral weight over a broad frequency range is evidence of the important role
+of electronic correlations to the metal-insulator transitions in both of these
+vanadium oxides. We observe a sharp optical transition with possible final
+state (exciton) effects in the insulating phase of VO2. This sharp optical
+transition occurs between narrow a1g bands that arise from the
+quasi-one-dimensional chains of vanadium dimers. Electronic correlations in the
+metallic phases of both VO2 and V2O3 lead to reduction of the kinetic energy of
+the charge carriers compared to band theory values, with paramagnetic metallic
+V2O3 showing evidence of stronger correlations compared to rutile metallic VO2.",0803.2739v1
+2008-03-29,Superconductivity at 52 K in iron-based F-doped layered quaternary compound Pr[O1-xFx]FeAs,"Since the discovery of copper oxide superconductor in 1986 [1], extensive
+efforts have been devoted to the search of new high-Tc superconducting
+materials, especially high-Tc systems other than cuprates. The recently
+discovered quaternary superconductor La[O1-xFx]FeAs with the superconducting
+critical transition Tc of 26 K [2], which has a much simple layered structure
+compared with cuprates, has attracted quick enthusiasm and is going to become a
+new high-Tc system [3-6]. Here we report the discovery of bulk
+superconductivity in the praseodymium-arsenide oxides Pr[O1-xFx]FeAs with an
+onset drop of resistivity as high as 52 K, and the unambiguous zero-resistivity
+and Meissner transition at low temperature, which will place these quaternary
+compounds to another high-Tc superconducting system explicitly.",0803.4283v1
+2008-04-04,Cavity-enhanced radiative emission rate in a single-photon-emitting diode operating at 0.5 GHz,"We report the observation of a Purcell enhancement in the electroluminescence
+decay rate of a single quantum dot, embedded in a microcavity
+light-emitting-diode structure. Lateral confinement of the optical mode was
+achieved using an annulus of low-refractive-index aluminium oxide, formed by
+wet oxidation. The same layer acts as a current aperture, reducing the active
+area of the device without impeding the electrical properties of the p-i-n
+diode. This allowed single photon electroluminescence to be demonstrated at
+repetition rates up to 0.5 GHz.",0804.0663v1
+2008-04-04,Photoluminescence of hexagonal boron nitride: effect of surface oxidation under UV-laser irradiation,"We report on the UV laser induced fluorescence of hexagonal boron nitride
+(h-BN) following nanosecond laser irradiation of the surface under vacuum and
+in different environments of nitrogen gas and ambient air. The observed
+fluorescence bands are tentatively ascribed to impurity and mono (VN), or
+multiple (m-VN with m = 2 or 3) nitrogen vacancies. A structured fluorescence
+band between 300 nm and 350 nm is assigned to impurity-band transition and its
+complex lineshape is attributed to phonon replicas. An additional band at 340
+nm, assigned to VN vacancies on surface, is observed under vacuum and quenched
+by adsorbed molecular oxygen. UV-irradiation of h-BN under vacuum results in a
+broad asymmetric fluorescence at ~400 nm assigned to m-VN vacancies; further
+irradiation breaks more B-N bonds enriching the surface with elemental boron.
+However, no boron deposit appears under irradiation of samples in ambient
+atmosphere. This effect is explained by oxygen healing of radiation-induced
+surface defects. Formation of the oxide layer prevents B-N dissociation and
+preserves the bulk sample stoichiometry.",0804.0764v1
+2008-04-05,Doubly degenerate orbital system in honeycomb lattice: implication of orbital state in layered iron oxide,"We study a doubly-degenerate orbital model on a honeycomb attice. This is a
+model for orbital states in multiferroic layered iron oxides. The classical and
+quantum models are analyzed by spin-wave approximation, Monte-Carlo simulation
+and Lanczos method. A macroscopic number of degeneracy exists in the classical
+ground state. In the classical model, a peak in the specific heat appears at a
+temperature which is much lower than the mean-field ordering one. Below this
+temperature, angle of orbital pseudo-spin is fixed, but conventional orbital
+orders are not suggested. The degeneracy in the ground state is partially
+lifted by thermal fluctuation. We suggest a role of zero-dimensional
+fluctuation in hexagons on a low-temperature orbital structure. Lifting of the
+degeneracy also occurs at zero temperature due to the quantum zero-point
+fluctuation. We show that the ground-state wave function is well represented by
+a linear combination of the states where a honeycomb lattice is covered by
+nearest-neighboring pairs of orbitals with the minimum bond energy.",0804.0843v1
+2008-05-07,Fabrication of Nanostructured PLGA Scaffolds Using Anodic Aluminum Oxide Templates,"PLGA (poly(lactic-co-glycolic acid)) is one of the most used biodegradable
+and biocompatible materials. Nanostructured PLGA even has great application
+potentials in tissue engineering. In this research, a fabrication technique for
+nanostructured PLGA membrane was investigated and developed. In this novel
+fabrication approach, an anodic aluminum oxide (AAO) film was use as the
+template ; the PLGA solution was then cast on it ; the vacuum air-extraction
+process was applied to transfer the nano porous pattern from the AAO membrane
+to the PLGA membrane and form nanostures on it. The cell culture experiments of
+the bovine endothelial cells demonstrated that the nanostructured PLGA membrane
+can double the cell growing rate. Compared to the conventional chemical-etching
+process, the physical fabrication method proposed in this research not only is
+simpler but also does not alter the characteristics of the PLGA. The
+nanostructure of the PLGA membrane can be well controlled by the AAO temperate.",0805.0879v1
+2008-05-09,Network rigidity and dynamics of oxides,"If a hierarchy of interatomic interactions exists in a solid, low-frequency
+modes can be found from viewing this solid as a mechanical network. In this
+case, the low-frequency modes are determined by the network rigidity. We study
+the low-frequency modes (rigid unit modes, or RUMs) in several important oxide
+materials and discuss how the RUMs affect their properties. In SiO$_2$ glass,
+the ability to support RUMs governs its relaxation in the wide range of
+pressures and temperatures, giving rise to the non-trivial pressure window. It
+also affects other properties, including crystallization, slow relaxation and
+compressibility. At ambient pressure and low temperature, RUM flexibility is
+related to the large-scale localized atomic motions. Whether these motions are
+interpreted as independent two-level systems or collective density excitations,
+the RUM flexibility determines whether and to what extent low-energy
+excitations can exist in a given glass structure. Finally, we discuss the RUM
+in, perhaps unexpectedly, cuprate superconductors, and its relevance for
+superconductivity, including the d-wave symmetry of the order parameter and
+other properties.",0805.1392v1
+2008-06-04,Nanolithography and manipulation of graphene using an atomic force microscope,"We use an atomic force microscope (AFM) to manipulate graphene films on a
+nanoscopic length scale. By means of local anodic oxidation with an AFM we are
+able to structure isolating trenches into single-layer and few-layer graphene
+flakes, opening the possibility of tabletop graphene based device fabrication.
+Trench sizes of less than 30 nm in width are attainable with this technique.
+Besides oxidation we also show the influence of mechanical peeling and
+scratching with an AFM of few layer graphene sheets placed on different
+substrates.",0806.0716v2
+2008-06-16,Band Jahn-Teller Instability and Formation of Valence Bond Solid in a Mixed-Valent Spinel Oxide LiRh2O4,"We have synthesized a new spinel oxide LiRh2O4 with a mixed-valent
+configuration of Rh3+ and Rh4+. At room temperature it is a paramagnetic metal,
+but on cooling, a metal-insulator transition occurs and a valence bond solid
+state is formed below 170 K. We argue that the formation of valence bond solid
+is promoted by a band Jahn-Teller transition at 230 K and the resultant
+confinement of t2g holes within the xy band. The band Jahn-Teller instability
+is also responsible for the observed enhanced thermoelectric power in the
+orbital disordered phase above 230 K.",0806.2504v2
+2008-08-04,Highly Conducting Graphene Sheets and Langmuir-Blodgett Films,"Graphene is an intriguing material with properties that are distinct from
+those of other graphitic systems. The first samples of pristine graphene were
+obtained by peeling off and epitaxial growth. Recently, the chemical reduction
+of graphite oxide was used to produce covalently functionalized single-layer
+graphene oxide. However, chemical approaches for the large-scale production of
+highly conducting graphene sheets remain elusive. Here, we report that the
+exfoliation-reintercalation-expansion of graphite can produce high-quality
+single-layer graphene sheets stably suspended in organic solvents. The graphene
+sheets exhibit high electrical conductance at room and cryogenic temperatures.
+Large amounts of graphene sheets in organic solvents are made into large
+transparent conducting films by Langmuir-Blodgett assembly in a layer-by-layer
+manner. The chemically derived high quality graphene sheets could lead to
+future scalable graphene devices.",0808.0502v1
+2008-09-21,Synthesis and characterization of chloride doped polyaniline by bulk oxidative chemical polymerization.Doping effect on electrical conductivity,"Conductive polymers or ""organic metals"" are highly engineered nanostructured
+materials made from organic building blocks. They are candidates as molecular
+wires for nanotechnology applications in molecular electronics. The conduction
+in these polymers is due to the presence of delocalized molecular orbitals. In
+this work, we present the synthesis of chloride doped polyaniline by bulk
+oxidative chemical polymerization using a solid aniline salt as a monomer
+instead of liquid aniline to diminish toxic hazards. The FTIR and UV-visible
+spectra confirmed the expected structure of the polymer. The electrical
+conductivity measured using a four-probe method was 1.7 S/cm. The dependence of
+impedance modulus on frequency was measured using an HP impedance analyzer in
+the range 10 kHz-13 MHz. The influence of doping and the preparation
+temperature on the electrical conductivity were also investigated.",0809.3552v1
+2008-09-26,Improved structural ordering in sexithiophene thick films grown on single crystal oxide substrates,"We report on sexithiophene films, about 150nm thick, grown by thermal
+evaporation on single crystal oxides and, as comparison, on Si/SiO2. By heating
+the entire deposition chamber at 100 C we obtain standing-up oriented molecules
+all over the bulk thickness. Surface morphology shows step-like islands, each
+step being only one monolayer height. The constant and uniform warming of the
+molecules obtained by heating the entire deposition chamber allows a stable
+diffusion-limited growth process. Therefore, the regular growth kinetic is
+preserved when increasing the thickness of the film. Electrical measurements on
+differently structured films evidence the impact of the inter island separation
+region size on the main charge transport parameters.",0809.4683v2
+2008-09-27,Tuning of metal-insulator transition of two-dimensional electrons at parylene/SrTiO$_3$ interface by electric field,"Electrostatic carrier doping using a field-effect-transistor structure is an
+intriguing approach to explore electronic phases by critical control of carrier
+concentration. We demonstrate the reversible control of the insulator-metal
+transition (IMT) in a two dimensional (2D) electron gas at the interface of
+insulating SrTiO$_3$ single crystals. Superconductivity was observed in a
+limited number of devices doped far beyond the IMT, which may imply the
+presence of 2D metal-superconductor transition. This realization of a
+two-dimensional metallic state on the most widely-used perovskite oxide is the
+best manifestation of the potential of oxide electronics.",0809.4774v1
+2008-10-05,Quantum Wells in Polar-Nonpolar Oxide Heterojunction Systems,"We address the electronic structure of quantum wells in polar-nonpolar oxide
+heterojunction systems focusing on the case of non-polar BaVO$_3$ wells
+surrounded by polar LaTiO$_3$ barriers. Our discussion is based on a density
+functional description using the local spin density approximation with local
+correlation corrections (LSDA+U). We conclude that a variety of quite different
+two-dimensional electron systems can occur at interfaces between insulating
+materials depending on band line-ups and on the geometrical arrangement of
+polarity discontinuities.",0810.0798v2
+2008-10-16,PBG properties of three-component 2D photonic crystals,"In this paper we analyze theoretically how the introduction of the third
+component into the two-dimensional photonic crystal influences the photonic
+band structure and the density-of-states of the system. We consider the
+periodic array of cylindrical air rods in a dielectric, and the third medium is
+introduced as a ring-shaped intermediate layer between the air pores and the
+dielectric background. Using the plane wave method, we have obtained the band
+structures for the 2D triangular lattice photonic crystals. The dependencies of
+TE and TM band gaps' widths and gaps' edges position on the interlayer
+dielectric constant and interlayer thickness were analyzed. In the framework of
+this approach, we have estimated the influence of the surface oxide layer on
+the band structure of macroporous silicon. We observed the shift of the gaps'
+edges to the higher or lower frequencies, depending on the interlayer thickness
+and dielectric constant. We have shown that the existence of a native oxide
+surface layer should be taken into consideration to understand the optical
+properties of 2D photonic crystals, particularly in macroporous silicon
+structures.",0810.2947v1
+2008-10-27,Systematic tight-binding analysis of ARPES spectra of transition-metal oxides,"We have performed systematic tight-binding (TB) analyses of the
+angle-resolved photoemission spectroscopy (ARPES) spectra of transition-metal
+(TM) oxides A$M$O$_3$ ($M=$ Ti, V, Mn, and Fe) with the perovskite-type
+structure and compared the obtained parameters with those obtained from
+configuration-interaction (CI) cluster-model analyses of photoemission spectra.
+The values of $\epsilon_d-\epsilon_p$ from ARPES are found to be similar to the
+charge-transfer energy $\Delta$ from O $2p$ orbitals to empty TM 3d orbitals
+and much larger than $\Delta-U/2$ ($U$: on-site Coulomb energy) expected for
+Mott-Hubbard-type compounds including SrVO$_3$. $\epsilon_d-\epsilon_p$ values
+from {\it ab initio} band-structure calculations show similar behaviors to
+those from ARPES. The values of the $p-d$ transfer integrals to describe the
+global electronic structure are found to be similar in all the estimates,
+whereas additional narrowing beyond the TB description occurs in the ARPES
+spectra of the $d$ band.",0810.4905v1
+2008-11-05,Enhancement of ferroelectricity at metal/oxide interfaces,"By performing first-principles calculations on four capacitor structures
+based on BaTiO3 and PbTiO3, we determine the intrinsic interfacial effects that
+are responsible for the destabilization of the polar state in thin-film
+ferroelectric devices. We show that, contrary to the established
+interpretation, the interfacial capacitance depends crucially on the local
+chemical environment of the interface through the force constants of the
+metal-oxide bonds, and is not necessarily related to the bulk screening
+properties of the electrode material. In particular, in the case of interfaces
+between AO-terminated perovskites and simple metals, we demonstrate a novel
+mechanism of ""interfacial ferroelectricity"" that produces an overall
+enhancement of the ferroelectric instability of the film, rather than a
+suppression as is usually assumed. The resulting ""negative dead layer"" suggests
+a route to thin-film ferroelectric devices that are free of deleterious size
+effects.",0811.0632v1
+2008-11-06,Ag-Cu alloy surfaces in an oxidizing environment: a first-principles study,"Recent experiments on model catalysts have shown that Ag-Cu alloys have
+improved selectivity with respect to pure silver for ethylene epoxidation. In
+this paper we review our first-principles investigations on the (111) surface
+of this alloy and present new findings on other low index surfaces. We find
+that, for every surface orientation, the presence of oxygen leads to copper
+segregation to the surface. Considering the alloy to be in equilibrium with an
+oxygen atmosphere and accounting for the effect of temperature and pressure, we
+compute the surface free energy and study the stability of several surface
+structures. Investigating the dependence of the surface free energy on the
+surface composition, we construct the phase diagram of the alloy for every
+surface orientation. Around the temperature, pressure and composition of
+interest for practical applications, we find that a limited number of
+structures can be present, including a thin layer of copper oxide on top of the
+silver surface and copper-free structures. Different surface orientations show
+a very similar behavior and in particular a single layer with CuO
+stoichiometry, significantly distorted when compared to a layer of bulk CuO,
+has a wide range of stability for all orientations. Our results are consistent
+with, and help explain, recent experimental measurements.",0811.0864v1
+2008-11-09,Comparison of Resonant Inelastic X-Ray Scattering Spectra and Dielectric Loss Functions in Copper Oxides,"We report empirical comparisons of Cu K-edge indirect resonant inelastic
+x-ray scattering (RIXS) spectra, taken at the Brillouin zone center, with
+optical dielectric loss functions measured in a number of copper oxides. The
+RIXS data are obtained for Bi$_2$CuO$_4$, CuGeO$_3$, Sr$_2$Cu$_3$O$_4$Cl$_2$,
+La$_2$CuO$_4$, and Sr$_2$CuO$_2$Cl$_2$, and analyzed by considering both
+incident and scattered photon resonances. An incident-energy-independent
+response function is then extracted. The dielectric loss functions, measured
+with spectroscopic ellipsometry, agree well with this RIXS response, especially
+in Bi$_2$CuO$_4$ and CuGeO$_3$.",0811.1379v1
+2008-11-15,Pentacene islands grown on ultra-thin SiO2,"Ultra-thin oxide (UTO) films were grown on Si(111) in ultrahigh vacuum at
+room temperature and characterized by scanning tunneling microscopy. The
+ultra-thin oxide films were then used as substrates for room temperature growth
+of pentacene. The apparent height of the first layer is 1.57 +/- 0.05 nm,
+indicating standing up pentacene grains in the thin-film phase were formed.
+Pentacene is molecularly resolved in the second and subsequent molecular
+layers. The measured in-plane unit cell for the pentacene (001) plane (ab
+plane) is a=0.76+/-0.01 nm, b=0.59+/-0.01 nm, and gamma=87.5+/-0.4 degrees. The
+films are unperturbed by the UTO's short-range spatial variation in tunneling
+probability, and reduce its corresponding effective roughness and correlation
+exponent with increasing thickness. The pentacene surface morphology follows
+that of the UTO substrate, preserving step structure, the long range surface
+rms roughness of ~0.1 nm, and the structural correlation exponent of ~1.",0811.2515v1
+2008-11-17,Thermal degradation of ligno-cellulosic fuels: DSC and TGA studies,"The scope of this work was to show the utility of thermal analysis and
+calorimetric experiments to study the thermal oxidative degradation of
+Mediterranean scrubs. We investigated the thermal degradation of four species;
+DSC and TGA were used under air sweeping to record oxidative reactions in
+dynamic conditions. Heat released and mass loss are important data to be
+measured for wildland fires modelling purpose and fire hazard studies on
+ligno-cellulosic fuels. Around 638 and 778 K, two dominating and overlapped
+exothermic peaks were recorded in DSC and individualized using a experimental
+and numerical separation. This stage allowed obtaining the enthalpy variation
+of each exothermic phenomenon. As an application, we propose to classify the
+fuels according to the heat released and the rate constant of each reaction.
+TGA experiments showed under air two successive mass loss around 638 and 778 K.
+Both techniques are useful in order to measure ignitability, combustibility and
+sustainability of forest fuels.",0811.2742v1
+2008-11-18,Controlling the efficiency of spin injection into graphene by carrier drift,"Electrical spin injection from ferromagnetic metals into graphene is hindered
+by the impedance mismatch between the two materials. This problem can be
+reduced by the introduction of a thin tunnel barrier at the interface. We
+present room temperature non-local spin valve measurements in
+cobalt/aluminum-oxide/graphene structures with an injection efficiency as high
+as 25%, where electrical contact is achieved through relatively transparent
+pinholes in the oxide. This value is further enhanced to 43% by applying a DC
+current bias on the injector electrodes, that causes carrier drift away from
+the contact. A reverse bias reduces the AC spin valve signal to zero or
+negative values. We introduce a model that quantitatively predicts the behavior
+of the spin accumulation in the graphene under such circumstances, showing a
+good agreement with our measurements.",0811.2960v1
+2008-11-27,Monolithic Pixel Sensors in Deep-Submicron SOI Technology with Analog and Digital Pixels,"This paper presents the design and test results of a prototype monolithic
+pixel sensor manufactured in deep-submicron fully-depleted Silicon-On-Insulator
+(SOI) CMOS technology. In the SOI technology, a thin layer of integrated
+electronics is insulated from a (high-resistivity) silicon substrate by a
+buried oxide. Vias etched through the oxide allow to contact the substrate from
+the electronics layer, so that pixel implants can be created and a reverse bias
+can be applied. The prototype chip, manufactured in OKI 0.15 micron SOI
+process, features both analog and digital pixels on a 10 micron pitch. Results
+of tests performed with infrared laser and 1.35 GeV electrons and a first
+assessment of the effect of ionising and non-ionising doses are discussed.",0811.4540v1
+2008-12-05,The role of static disorder in negative thermal expansion in ReO3,"Time-of-flight neutron powder diffraction and specific heat measurements were
+used to study the nature of thermal expansion in rhenium trioxide, an
+electrically conducting oxide with cubic symmetry. The temperature evolution of
+the lattice parameters show that ReO3 can exhibit negative thermal expansion at
+low temperatures and that the transition from negative to positive thermal
+expansion depends on sample preparation; the single crystal sample demonstrated
+the highest transition temperature, 300 K, and largest negative value for the
+coefficient of thermal expansion, alpha = -1.1(1)x 10^-6 K^-1. For the oxygen
+atoms, the atomic displacement parameters are strongly anisotropic even at 15
+K, indicative of a large contribution of static disorder to the displacement
+parameters. Further inspection of the temperature evolution of the oxygen
+displacement parameters for different samples reveals that the static disorder
+contribution is greater for the samples with diminished NTE behavior. In
+addition, specific heat measurements show that ReO3 lacks the low energy
+Einstein-type modes seen in other negative thermal expansion oxides such as
+ZrW2O8.",0812.1187v1
+2008-12-18,Reduced leakage current in Josephson tunnel junctions with codeposited barriers,"Josephson junctions were fabricated using two different methods of barrier
+formation. The trilayers employed were Nb/Al-AlOx/Nb on sapphire, where the
+first two layers were epitaxial. The oxide barrier was formed either by
+exposing the Al surface to O2 or by codepositing Al in an O2 background. The
+codeposition process yielded junctions that showed the theoretically predicted
+subgap current and no measurable shunt conductance. In contrast, devices with
+barriers formed by thermal oxidation showed a small shunt conductance in
+addition to the predicted subgap current.",0812.3636v3
+2009-01-23,Fabrication of nanotubules of thermoelectric gamma-Na0.7CoO2 using porous aluminum oxide membrane as supporting template,"We report the successful synthesis of nanotubules of thermoelectric materials
+gamma-NaxCoO2 using two different sol-gel routes aided by porous anodized
+aluminium oxide (AAO) membrane as supporting templates. The gamma-NaxCoO2
+nanotubule using urea-based route can be achieved at 650 degree C at a heating
+rate of 1 degree C/min and held for 4h. The gamma-NaxCoO2 nanotubule using
+citric acid-based route can be achieved at 500 degree C using a rapid-heat-up
+procedure and held for 30 min. The products were investigated using various
+techniques including XRD, SEM and TEM. Electron diffraction pattern taken along
+[001] zone axis direction on the nanotubule shows that all the diffraction
+spots can be indexed using a hexagonal unit cell with a = b = 0.56 nm, which
+can be considered as a superstructure with cell doubling within the ab plane.",0901.3628v1
+2009-02-07,Engineering graphene by oxidation: a first principles study,"Graphene epoxide, with oxygen atoms lining up on pristine graphene sheets, is
+investigated theoretically in this Letter. Two distinct phases: metastable
+clamped and unzipped structures are unveiled in consistence with experiments.
+In the stable (unzipped) phase, epoxy group breaks underneath sp2 bond and
+modifies the mechanical and electronic properties of graphene remarkably. The
+foldable epoxy ring structure reduces its Young's modulus by 42.4%, while
+leaves the tensile strength almost unchanged. Epoxidation also perturbs the pi
+state and opens semiconducting gap for both phases, with dependence on the
+density of epoxidation. In the unzipped structures, localized states revealed
+near the Fermi level resembles the edge states in graphene nanoribbons. The
+study reported here paves the way for oxidation-based functionalization of
+graphene-related materials.",0902.1237v1
+2009-02-21,The f-electron challenge: localized and itinerant states in lanthanide oxides united by GW@LDA+U,"Many-body perturbation theory in the GW approach is applied to lanthanide
+oxides, using the local-density approximation plus a Hubbard U correction
+(LDA+U) as the starting point. Good agreement between the G0W0 density of
+states and experimental spectra is observed for CeO2 and Ce2O3. Unlike the
+LDA+U method G0W0 exhibits only a weak dependence on U in a physically
+meaningful range of U values. For the whole lanthanide sesquioxide (Ln2O3)
+series G0W0@LDA+U reproduces the main features found for the optical
+experimental band gaps. The relative positions of the occupied and unoccupied
+f-states predicted by G0W0 confirm the experimental conjecture derived from
+phenomenological arguments.",0902.3697v1
+2009-03-13,Probing the interface of Fe3O4/GaAs thin films by hard x-ray photoelectron spectroscopy,"Magnetite (Fe3O4) thin films on GaAs have been studied with HArd X-ray
+PhotoElectron Spectroscopy (HAXPES) and low-energy electron diffraction. Films
+prepared under different growth conditions are compared with respect to
+stoichiometry, oxidation, and chemical nature. Employing the considerably
+enhanced probing depth of HAXPES as compared to conventional x-ray
+photoelectron spectroscopy (XPS) allows us to investigate the chemical state of
+the film-substrate interfaces. The degree of oxidation and intermixing at the
+interface are dependent on the applied growth conditions; in particular, we
+found that metallic Fe, As2O3, and Ga2O3 exist at the interface. These
+interface phases might be detrimental for spin injection from magnetite into
+GaAs.",0903.2377v1
+2009-03-18,Monolithic Pixel Sensors in Deep-Submicron SOI Technology,"Monolithic pixel sensors for charged particle detection and imaging
+applications have been designed and fabricated using commercially available,
+deep-submicron Silicon-On-Insulator (SOI) processes, which insulate a thin
+layer of integrated full CMOS electronics from a high-resistivity substrate by
+means of a buried oxide. The substrate is contacted from the electronics layer
+through vias etched in the buried oxide, allowing pixel implanting and reverse
+biasing. This paper summarizes the performances achieved with a first prototype
+manufactured in the OKI 0.15 micrometer FD-SOI process, featuring analog and
+digital pixels on a 10 micrometer pitch. The design and preliminary results on
+the analog section of a second prototype manufactured in the OKI 0.20
+micrometer FD-SOI process are briefly discussed.",0903.3205v1
+2009-03-30,Interface relaxation and electrostatic charge depletion in the oxide heterostructure LaAlO3/SrTiO3,"Performing an analysis within density functional theory, we develop insight
+into the structural and electronic properties of the oxide heterostructure
+LaAlO3/SrTiO3. Electrostatic surface effects are decomposed from the internal
+lattice distortion in order to clarify their interplay. We first study the
+interface relaxation by a multi-layer system without surface, and the surface
+effects, separately, by a substrate-film system. While elongation of the TiO6
+octahedra at the interface enhances the metallicity, reduction of the film
+thickness has the opposite effect due to a growing charge depletion. The
+interplay of these two effects, as reflected by the full lattice relaxation in
+the substrate-film system, however, strongly depends on the film thickness. An
+inversion of the TiO6 distortion pattern for films thinner than four LaAlO3
+layers results in an insulating state.",0903.5196v1
+2009-04-06,"New Series of Nickel-Based Pnictide Oxide Superconductors (Ni2Pn2)(Sr4Sc2O6) (Pn = P, As)","We have discovered new nickel-based pnictide oxide superconductors,
+(Ni2Pn2)(Sr4Sc2O6) (Pn = P, As). These compounds have a tetragonal unit cell
+with a space group of P4/nmm and they consist of alternate stacking of
+anti-fluorite Ni2Pn2 layers and K2NiF4-type Sr4Sc2O6 blocking layers. Lattice
+parameters were a = 4.044 A and c = 15.23 A for (Ni2P2)(Sr4Sc2O6) and a = 4.078
+A and c = 15.41 A for (Ni2As2)(Sr4Sc2O6), indicating their thicker blocking
+layers than that of LaNiPO (c ~ 8.1 A). Both (Ni2P2)(Sr4Sc2O6) and
+(Ni2As2)(Sr4Sc2O6) exhibited superconductivity with zero resistivity at 3.3 K
+and 2.7 K, respectively. The perfect diamagnetism observed in both compounds
+guaranteed their bulk superconductivity.",0904.0825v4
+2009-04-15,Some properties of a long lifetime strongly-coupled molecular plasma produced by high Rydberg excitation of nitric oxide in a supersonic free jet,"A long life-time (>0.3 ms) strongly-coupled molecular Rydberg plasma is
+generated by the excitation of nitric oxide into the high-n Rydberg threshold
+region in the high-density region of a supersonic jet expansion. After 310 \mus
+the plasma has expanded to a size of ca. 3 cm. When subjected to very small DC
+fields from 0.2 to 1.0 V/cm the plasma reveals a much smaller high-density core
+structure of only 0.6 cm. The molecular Rydberg plasma is observed over a broad
+range of excitation energies, from threshold down to Rydberg states as low as n
+= 19.",0904.2280v3
+2009-04-20,Theoretical kinetic study of the low temperature oxidation of ethanol,"In order to improve the understanding of the low temperature combustion of
+ethanol, high-level ab initio calculations were performed for elementary
+reactions involving hydroxyethylperoxy radicals. These radicals come from the
+addition of hydroxethyl radicals (?CH3CHOH and ?CH2CH2OH) on oxygen molecule.
+Unimolecular reactions involving hydroxyethylperoxy radicals and their radical
+products were studied at the CBS-QB3 level of theory. The results allowed to
+highlight the principal ways of decomposition of these radicals. Calculations
+of potential energy surfaces showed that the principal channels lead to the
+formation of HO2 radicals which can be considered, at low temperature, as
+slightly reactive. However, in the case of CH3CH(OOH)O? radicals, a route of
+decomposition yields H atom and formic peracid, which is a branching agent that
+can strongly enhance the reactivity of ethanol in low temperature oxidation. In
+addition to these analyses, high-pressure limit rate constants were derived in
+the temperature range 400 to 1000 K.",0904.2974v1
+2009-04-30,Fundamental asymmetry in interfacial electronic reconstruction between insulating oxides,"We present an ab initio study of the (001) interfaces between two insulating
+perovskites, the polar LaAlO3 and the nonpolar SrTiO3. We observe an
+insulating-to-metallic transition above a critical LaAlO3 thickness. We explain
+that the high conductivity observed at the TiO2 /LaO interface and the lack of
+similar conductivity at the SrO/AlO2 interface are inherent in the atomic
+geometry of the system. A large interfacial hopping matrix element between
+cations causes the formation of a bound electron state at the TiO2 /LaO
+interface. This mechanism for the formation of interfacial bound states
+suggests a robust means for tuning conductivities at various oxide
+heterointerfaces.",0904.4734v1
+2009-05-06,Oxide superlattices with alternating p and n interfaces,"The physics of oxide superlattices is considered for pristine (001)
+multilayers of the band insulators LaAlO3 and SrTiO3 with alternating p and n
+interfaces. First principles results and a model of capacitor plates offer a
+simple paradigm to understand their dielectric properties and the insulator to
+metal transition (IMT) at interfaces with increasing layer thickness. The
+charge at insulating interfaces is found to be as predicted from the formal
+ionic charges, not populations. Different relative layer thicknesses produce a
+spontaneous polarization of the system, and allow manipulation of the
+interfacial electron gas. Large piezoresistance effects can be obtained from
+the sensitivity of the IMT to lateral strain. Carrier densities are found to be
+ideal for exciton condensation.",0905.0881v3
+2009-05-08,Double-gated graphene-based devices,"We discuss transport through double gated single and few layer graphene
+devices. This kind of device configuration has been used to investigate the
+modulation of the energy band structure through the application of an external
+perpendicular electric field, a unique property of few layer graphene systems.
+Here we discuss technological details that are important for the fabrication of
+top gated structures, based on electron-gun evaporation of SiO$_2$. We perform
+a statistical study that demonstrates how --contrary to expectations-- the
+breakdown field of electron-gun evaporated thin SiO$_2$ films is comparable to
+that of thermally grown oxide layers. We find that a high breakdown field can
+be achieved in evaporated SiO$_2$ only if the oxide deposition is directly
+followed by the metallization of the top electrodes, without exposure to air of
+the SiO$_2$ layer.",0905.1221v2
+2009-06-09,Initial stages of nickel oxide growth on Ag(001) by pulsed laser deposition,"Submonolayers of nickel oxide films were grown on an Ag(001) by pulsed laser
+deposition, and characterized in-situ by both scanning tunneling microscopy and
+X-ray photoelectron spectroscopy. We observed quasi-two-dimensional growth of
+the film, and clearly identified several kinds of defects, such as embedded
+metallic Ni clusters and, notably, oxygen atoms, even while looking deeply into
+the substrate. These originated from Ni and O hyperthermal projectiles as well
+as from NiO clusters that were formed during laser ablation of a NiO target.
+Those defects played a role of nucleation sites in extending the nucleation
+stage of thin film growth.",0906.1653v3
+2009-06-25,Rattling-Induced Superconductiviy in the Beta-Pyrochlore Oxides AOs2O6,"The superconducting properties of two beta-pyrochlore oxides, CsOs2O6 and
+RbOs2O6, are studied by thermodynamic and transport measurements using
+high-quality single crystals. It is shown that the character of
+superconductivity changes systematically from weak coupling for CsOs2O6 to
+moderately strong coupling for RbOs2O6, and finally to extremely strong
+coupling with BCS-type superconductivity for KOs2O6, with increasing Tc.
+Strong-coupling correction analyses of the superconducting properties reveal
+that a low-energy rattling mode of the alkali metal ions is responsible for the
+mechanism of the superconductivity in each compound. The large enhancement of
+Tc from Cs to K is attributed to the increase in the electron-rattler coupling
+with decreasing characteristic energy of the rattling and with increasing
+anharmonicity. The existence of weak anisotropy in the superconducting gap or
+in the electron-rattler interactions is found for the Cs and Rb compounds.",0906.4656v1
+2009-06-27,Resistive switching in nanogap systems on SiO2 substrates,"Voltage-controlled resistive switching is demonstrated in various gap systems
+on SiO2 substrate. The nanosized gaps are made by different means using
+different materials including metal, semiconductor, and metallic nonmetal. The
+switching site is further reduced by using multi-walled carbon nanotubes and
+single-walled carbon nanotubes. The switching in all the gap systems shares the
+same characteristics. This independence of switching on the material
+compositions of the electrodes, accompanied by observable damage to the SiO2
+substrate at the gap region, bespeaks the intrinsic switching from
+post-breakdown SiO2. It calls for caution when studying resistive switching in
+nanosystems on oxide substrates, since oxide breakdown extrinsic to the
+nanosystem can mimic resistive switching. Meanwhile, the high ON/OFF ratio
+(10E5), fast switching time (2 us, test limit), durable cycles demonstrated
+show promising memory properties. The intermediate states observed reveal the
+filamentary conduction nature.",0906.5100v1
+2009-06-29,Stratospheric Albedo Modification by Aerosol Injection,"This paper reviews and develops the proposal, widely discussed but not
+examined in detail, to use stratospheric aerosols to increase the Earth's
+albedo to Solar radiation in order to control climate change. The potential of
+this method has been demonstrated by the ""natural experiments"" of volcanic
+injection of sulfate aerosols into the stratosphere that led to subsequent
+observed global cooling. I consider several hygroscopic oxides as possible
+aerosol materials in addition to oxides of sulfur. Aerosol chemistry,
+dispersion and transport have been the subject of little study and are not
+understood, representing a significant scientific risk. Even the optimal
+altitude of injection and aerosol size distribution are poorly known. Past
+attention focused on guns and airplanes as means of lofting aerosols or their
+chemical precursors, but large sounding rockets are cheap, energetically
+efficient, can be designed to inject aerosols at any required altitude, and
+involve little technical risk. Sophisticated, mass-optimized ""engineered""
+particles have been proposed as possible aerosols, but the formidable problems
+of their production in quantity, lofting and dispersion have not been
+addressed.",0906.5307v1
+2009-07-09,Cotunnite-structured titanium dioxide: the hardest known oxide,"Despite great technological importance and many investigations, a material
+with measured hardness comparable to that of diamond or cubic boron nitride has
+yet to be identified. Combined theoretical and experimental investigations led
+to the discovery of a new polymorph of titanium dioxide with titanium
+nine-coordinated to oxygen in the cotunnite (PbCl2) structure. Hardness
+measurements on the cotunnite-structured TiO2 synthesized at pressures above 60
+GPa and temperatures above 1000 K reveal that this material is the hardest
+oxide yet discovered. Furthermore, it is one of the least compressible (with a
+measured bulk modulus of 431 GPa) and hardest (with a microhardness of 38 GPa)
+polycrystalline materials studied thus far.",0907.1464v1
+2009-07-16,Dependence of Band Renormalization Effect on the Number of Copper-oxide Layers in Tl-based Copper-oxide Superconductor using Angle-resolved Photoemission Spectroscopy,"Here we report the first angle-resolved photoemission measurement on nearly
+optimally-doped multi-layer Tl-based superconducting cuprates (Tl-2212 and
+Tl-1223) and a comparison study to single layer (Tl-2201) compound. A ""kink"" in
+the band dispersion is found in all three compounds but exhibits different
+momentum dependence for the single layer and multi-layer compounds, reminiscent
+to that of Bi-based cuprates. This layer number dependent renormalization
+effect strongly implies that the spin resonance mode is unlikely responsible
+for the dramatic renormalization effect near the antinodal region.",0907.2747v1
+2009-08-10,Nanometer-scale striped surface terminations on fractured SrTiO$_{3}$ surfaces,"Using cross-sectional scanning tunneling microscopy on in situ fractured
+SrTiO$_{3}$, one of the most commonly used substrates for the growth of complex
+oxide thin films and superlattices, atomically smooth terraces have been
+observed on (001) surfaces. Furthermore, it was discovered that fracturing this
+material at room temperature results in the formation of stripe patterned
+domains having characteristic widths (~10 nm to ~20 nm) of alternating surface
+terminations that extend over a long-range. Spatial characterization utilizing
+spectroscopy techniques revealed a strong contrast in the electronic structure
+of the two domains. Combining these results with topographic data, we are able
+to assign both TiO$_{2}$ and SrO terminations to their respective domains. The
+results of this proof-of-principle experiment reveal that fracturing this
+material leads to reproducibly flat surfaces that can be characterized at the
+atomic-scale and suggests that this technique can be utilized for the study of
+technologically relevant complex oxide interfaces.",0908.1419v1
+2009-08-13,Structure and morphology of hydroxylated nickel oxide (111) surfaces,"We report an experimental and theoretical analysis of the sqrt(3)x
+sqrt(3)-R30 and 2x2 reconstructions on the NiO (111) surface combining
+transmission electron microscopy, x-ray photoelectron spectroscopy, and
+reasonably accurate density functional calculations using the meta-GGA hybrid
+functional TPSSh. While the main focus here is on the surface structure, we
+also observe an unusual step morphology with terraces containing only even
+numbers of unit cells during annealing of the surfaces. The experimental data
+clearly shows that the surfaces contain significant coverage of hydroxyl
+terminations, and the surface structures are essentially the same as those
+reported on the MgO (111) surface implying an identical kinetically-limited
+water-driven structural transition pathway. The octapole structure can
+therefore be all but ruled out for single crystals of NiO annealed in or
+transported through humid air. . The theoretical analysis indicates, as
+expected, that simple density functional theory methods for such
+strongly-correlated oxide surfaces are marginal, while better consideration of
+the metal d-electrons has a large effect although, it is still not perfect.",0908.1888v1
+2009-08-18,Detection of a single-charge defect in a metal-oxide-semiconductor structure using vertically coupled Al and Si single-electron transistors,"An Al-AlO_x-Al single-electron transistor (SET) acting as the gate of a
+narrow (~ 100 nm) metal-oxide-semiconductor field-effect transistor (MOSFET)
+can induce a vertically aligned Si SET at the Si/SiO_2 interface near the
+MOSFET channel conductance threshold. By using such a vertically coupled Al and
+Si SET system, we have detected a single-charge defect which is tunnel-coupled
+to the Si SET. By solving a simple electrostatic model, the fractions of each
+coupling capacitance associated with the defect are extracted. The results
+reveal that the defect is not a large puddle or metal island, but its size is
+rather small, corresponding to a sphere with a radius less than 1 nm. The small
+size of the defect suggests it is most likely a single-charge trap at the
+Si/SiO_2 interface. Based on the ratios of the coupling capacitances, the
+interface trap is estimated to be about 20 nm away from the Si SET.",0908.2479v1
+2009-08-25,Bipolar resistive switching in amorphous titanium oxide thin films,"Using isothermal and temperature-dependent electrical measurements, we
+investigated the resistive switching mechanism of amorphous titanium oxide thin
+films deposited by a plasma-enhanced atomic layer deposition method between two
+aluminum electrodes. We found a bipolar resistive switching behavior in the
+high temperature region (> 140 K), and two activation energies of shallow
+traps, 0.055 eV and 0.126 eV in the ohmic current regime. We also proposed that
+the bipolar resistive switching of amorphous TiO2 thin films is governed by the
+transition of conduction mode from a bulk-limited SCLC model (Off state) to an
+interface-limited Schottky emission (On state), generated by the ionic movement
+of oxygen vacancies.",0908.3525v1
+2009-09-13,Blue photoluminescence from chemically derived graphene oxide,"Fluorescent organic compounds are of significant importance to the
+development of low-cost opto-electronic devices. Blue fluorescence from
+aromatic or olefinic molecules and their derivatives is particularly important
+for display and lighting applications. Thin film deposition of
+low-molecular-weight fluorescent organic compounds typically requires costly
+vacuum evaporation systems. On the other hand, solution-processable polymeric
+counterparts generally luminesce at longer wavelengths due to larger
+delocalization in the chain. Blue light emission from solution-processed
+materials is therefore of unique technological significance. Here we report
+near-UV to blue photoluminescence (PL) from solution-processed graphene oxide
+(GO). The characteristics of the PL and its dependence on the reduction of GO
+indicates that it originates from the recombination of electron-hole (e-h)
+pairs localized within small sp2 carbon clusters embedded within an sp3 matrix.
+These results suggest that a sheet of graphene provides a parent structure on
+which fluorescent components can be chemically engineered without losing the
+macroscopic structural integrity. Our findings offer a unique route towards
+solution-processable opto-electronics devices with graphene.",0909.2456v1
+2009-09-23,Intermediate-valence behavior of the transition-metal oxide CaCu$_3$Ru$_4$O$_{12}$,"The transition--metal oxide CaCu$_3$Ru$_4$O$_{12}$ with perovskite--type
+structure shows characteristic properties of an intermediate--valence system.
+The temperature--dependent susceptibility exhibits a broad maximum around $150
+- 160$ K. At this temperature, neutron powder diffraction reveals a small but
+significant volume change whereby the crystal structure is preserved. Moreover,
+the temperature--dependent resistivity changes its slope. NMR Knight shift
+measurements of Ru reveal a cross--over from high temperature paramagnetic
+behavior of localized moments to itinerant band states at low temperatures.
+Additional density--functional theory calculations can relate the structural
+anomaly with the $d$--electron number. The different experimental and
+calculational methods result in a mutually consistent description of
+CaCu$_3$Ru$_4$O$_{12}$ as an intermediate--valent system in the classical sense
+of having low--energy charge fluctuations.",0909.4208v1
+2009-09-25,"Fluorescent Carbon Nanoparticle: Synthesis, Characterization and Bio-imaging Application","Fluorescent carbon nanoparticle (CNP) having 2-6 nm in size with quantum
+yield of about ~3% were synthesized via nitric acid oxidation of carbon soot
+and this approach can be used for milligram scale synthesis of these water
+soluble particles. These CNPs are nano-crystalline with predominantly graphitic
+structure and shows green fluorescence under UV exposure. While nitric acid
+oxidation induces nitrogen and oxygen incorporation into soot particle that
+afforded water solubility and light emitting property; the isolation of small
+particles from a mixture of different size particles improved the fluorescence
+quantum yield. These CNP shows encouraging cell imaging application. They enter
+into cell without any further functionalization and fluorescence property of
+these particles can be used for fluorescence based cell imaging application.",0909.4622v1
+2009-10-22,Metal-insulator transition through a semi-Dirac point in oxide nanostructures: VO$_2$ (001) layers confined within TiO$_2$,"Multilayer (TiO$_2$)$_m$/(VO$_2$)$_n$ nanostructures ($d^1$ - $d^0$
+interfaces with no polar discontinuity) show a metal-insulator transition with
+respect to the VO$_2$ layer thickness in first principles calculations. For $n$
+$\geq$ 5 layers, the system becomes metallic, while being insulating for $n$ =
+1 and 2. The metal-insulator transition occurs through a semi-Dirac point phase
+for $n$ = 3 and 4, in which the Fermi surface is point-like and the electrons
+behave as massless along the zone diagonal in k-space and as massive fermions
+along the perpendicular direction. We provide an analysis of the evolution of
+the electronic structure through this unprecedented insulator-to-metal
+transition, and identify it as resulting from quantum confinement producing a
+non-intuitive orbital ordering on the V $d^1$ ions, rather than being a
+specific oxide interface effect. Spin-orbit coupling does not destroy the
+semi-Dirac point for the calculated ground state, where the spins are aligned
+along the rutile c-axis, but it does open a substantial gap if the spins lie in
+the basal plane.",0910.4411v1
+2009-10-30,Charge and orbital ordering in Fe and Mn perovskite oxides far from half- doping by resonant x- ray scattering,"The emergence of superlattice periodicities at metal to insulator transitions
+in hole doped perovskite oxides responds to a rearrangement of the local atomic
+structure, and electron and spin density distribution. Originally, the ionic
+model based on a checkerboard- type atomic distribution served to describe the
+low temperature charge and orbital ordered (COO) phases arising in half- doped
+manganites. In the last years, the exploitation of resonant x- ray scattering
+(RXS) capabilities has shown the need to revisit these concepts and improve the
+picture. Yet, we have realised that COO is a more common phenomenon than
+expected that can be observed in a wide range of doping levels. Here we compare
+the experimental data recently collected by RXS on La_0.4Sr_1.6MnO_4 (x=0.60)
+and La(Pr)_1/3Sr_2/3FeO_3 (x=0.67). The first shows a COO phase similar to that
+found in the x=0.5 sample but angular peak positions vs. T denotes the
+incommensurability of superlattice reflections. Meanwhile, the analysis of the
+commensurate CO phase in the studied ferrite underlines the role of the
+structural changes also involving La(Sr) and O atoms.",0910.5788v1
+2009-11-02,Non-monotonic Fermi surface evolution and its correlation with stripe ordering in bilayer manganites,"In correlated electron systems such as cuprate superconductors and colossal
+magnetoresistive (CMR) oxides there is often a tendency for a nanoscale
+self-organization of electrons that can give rise to exotic properties and to
+extreme non-linear responses. The driving mechanisms for this self-organization
+are highly debated, especially in the CMR oxides in which two types of
+self-organized stripes of charge and orbital order coexist with each other. By
+utilizing angle-resolved photoemission spectroscopy measurements over a wide
+doping range, we show that one type of stripe is exclusively linked to long
+flat portions of nested Fermi surface, while the other type prefers to be
+commensurate with the real space lattice but also may be driven away from this
+by the Fermi surface. Complementarily, the Fermi surface also appears to be
+driven away from its non-interacting value at certain doping levels, giving
+rise to a host of unusual electronic properties.",0911.0439v1
+2010-01-08,Preparation of light-atom tips for Scanning Probe Microscopy by explosive delamination,"To obtain maximal resolution in STM and AFM, the size of the protruding tip
+orbital has to be minimized. Beryllium as tip material is a promising candidate
+for enhanced resolution because a beryllium atom has just four electrons,
+leading to a small covalent radius of only 96 pm. Besides that, beryllium is
+conductive and has a high elastic modulus, which is a necessity for a stable
+tip apex. However beryllium tips that are prepared ex situ, are covered with a
+robust oxide layer, which cannot be removed by just heating the tip. Here we
+present a successful preparation method that combines the heating of the tip by
+field emission and a mild collision with a clean metal plate. That method
+yields a clean, oxide-free tip surface as proven by a work function of as
+deduced from a current-distance curve. Additionally, a STM image of the
+Si-(111)-(7x7) is presented to prove the single-atom termination of the
+beryllium tip.",1001.1321v1
+2010-01-11,Catalyst preparation for CMOS-compatible silicon nanowire synthesis,"Metallic contamination was key to the discovery of semiconductor nanowires,
+but today it stands in the way of their adoption by the semiconductor industry.
+This is because many of the metallic catalysts required for nanowire growth are
+not compatible with standard CMOS (complementary metal oxide semiconductor)
+fabrication processes. Nanowire synthesis with those metals which are CMOS
+compatible, such as aluminium and copper, necessitate temperatures higher than
+450 C, which is the maximum temperature allowed in CMOS processing. Here, we
+demonstrate that the synthesis temperature of silicon nanowires using copper
+based catalysts is limited by catalyst preparation. We show that the
+appropriate catalyst can be produced by chemical means at temperatures as low
+as 400 C. This is achieved by oxidizing the catalyst precursor, contradicting
+the accepted wisdom that oxygen prevents metal-catalyzed nanowire growth. By
+simultaneously solving material compatibility and temperature issues, this
+catalyst synthesis could represent an important step towards real-world
+applications of semiconductor nanowires.",1001.1725v1
+2010-01-13,Compact and explicit physical model for lateral metal-oxide-semiconductor field-effect transistor with nanoelectromechanical system based resonant gate,"We propose a simple analytical model of a metal-oxide-semiconductor
+field-effect transistor with a lateral resonant gate based on the coupled
+electromechanical equations, which are self-consistently solved in time. All
+charge densities according to the mechanical oscillations are evaluated. The
+only input parameters are the physical characteristics of the device. No extra
+mathematical parameters are used to fit the experimental results. Theoretical
+results are in good agreement with the experimental data in static and dynamic
+operation. Our model is comprehensive and may be suitable for any
+electromechanical device based on the field-effect transduction.",1001.2148v1
+2010-02-18,Logarithmic behavior of degradation dynamics in metal--oxide semiconductor devices,"In this paper the authors describe a theoretical simple statistical modelling
+of relaxation process in metal-oxide semiconductor devices that governs its
+degradation. Basically, starting from an initial state where a given number of
+traps are occupied, the dynamics of the relaxation process is measured
+calculating the density of occupied traps and its fluctuations (second moment)
+as function of time. Our theoretical results show a universal logarithmic law
+for the density of occupied traps $\bar{<n(t)>} \sim \phi (T,E_{F}) (A+B \ln
+t)$, i.e., the degradation is logarithmic and its amplitude depends on the
+temperature and Fermi Level of device. Our approach reduces the work to the
+averages determined by simple binomial sums that are corroborated by our Monte
+Carlo simulations and by experimental results from literature, which bear in
+mind enlightening elucidations about the physics of degradation of
+semiconductor devices of our modern life.",1002.3571v1
+2010-02-18,Ferromagnetic transition in the double-exchange model on the pyrochlore lattice,"The double-exchange model, which has been extensively studied in the context
+of colossal magneto-resistance in perovskite manganese oxides, is known to
+exhibit a ferromagnetic metallic state at low temperatures because of the
+interplay between localized moments and itinerant electrons through the
+Hund's-rule coupling. Here we investigate numerically the ferromagnetic
+transition in the double-exchange model defined on the frustrated pyrochlore
+lattice as a simple model for ferromagnetic pyrochlore oxides. We demonstrate
+that the finite-size corrections are largely reduced by implementing averages
+over the twisted boundary conditions in the Monte Carlo simulation, which
+enables to estimate the ferromagnetic transition temperature in relatively
+small size clusters. The estimate is compared with that for the non-frustrated
+cubic lattice system.",1002.3642v1
+2010-02-26,Deep level transient spectroscopy study for the development of ion-implanted silicon field-effect transistors for spin-dependent transport,"A deep level transient spectroscopy (DLTS) study of defects created by
+low-fluence, low-energy ion implantation for development of ion-implanted
+silicon field-effect transistors for spin-dependent transport experiments is
+presented. Standard annealing strategies are considered to activate the
+implanted dopants and repair the implantation damage in test
+metal-oxide-semiconductor (MOS) capacitors. Fixed oxide charge, interface
+trapped charge and the role of minority carriers in DLTS are investigated. A
+furnace anneal at 950 $\rm ^{o}$C was found to activate the dopants but did not
+repair the implantation damage as efficiently as a 1000 $\rm ^{o}$C rapid
+thermal anneal. No evidence of bulk traps was observed after either of these
+anneals. The ion- implanted spin-dependent transport device is shown to have
+expected characteristics using the processing strategy determined in this
+study.",1002.4934v1
+2010-03-09,Stability of exfoliated Bi$_2$Sr$_2$Dy$_x$Ca$_{1-x}$Cu$_2$O$_{8+δ}$ studied by Raman microscopy,"Nanometer thick cuprates are an appealing platform for devices as well as
+exploring the roles of dimensionality, disorder, and free carrier density in
+these compounds. To this end we have produced exfoliated crystals of
+Bi2Sr2CaCu2O8 on oxidized silicon substrates. The exfoliated crystals were
+characterized via Atomic Force and polarized Raman microscopies. Proper
+procedures for production, handling and monitoring of these thin oxides are
+described. Subtle differences between the exfoliated and bulk crystals are also
+discussed.",1003.1979v2
+2010-03-12,Exchange bias and interface electronic structure in Ni/Co3O4(011),"A detailed study of the exchange bias effect and the interfacial electronic
+structure in Ni/Co3O4(011) is reported. Large exchange anisotropies are
+observed at low temperatures, and the exchange bias effect persists to
+temperatures well above the Neel temperature of bulk Co3O4, of about 40 K: to
+~80 K for Ni films deposited on well ordered oxide surfaces, and ~150 K for Ni
+films deposited on rougher Co3O4 surfaces. Photoelectron spectroscopy
+measurements as a function of Ni thickness show that Co reduction and Ni
+oxidation occur over an extended interfacial region. We conclude that the
+exchange bias observed in Ni/Co3O4, and in similar ferromagnetic metallic/Co3O4
+systems, is not intrinsic to Co3O4 but rather due to the formation of CoO at
+the interface.",1003.2478v1
+2010-04-19,Cu_{2}O as nonmagnetic semiconductor for spin transport in crystalline oxide electronics,"We probe spin transport in Cu_{2}O by measuring spin valve effect in
+La_{0.7}Sr_{0.3}MnO_{3}/Cu_{2}O/Co and
+La_{0.7}Sr_{0.3}MnO_{3}/Cu_{2}O/La_{0.7}Sr_{0.3}MnO_{3} epitaxial
+heterostructures. In La_{0.7}Sr_{0.3}MnO_{3}/Cu_{2}O/Co systems we find that a
+fraction of out-of-equilibrium spin polarized carrier actually travel across
+the Cu_{2}O layer up to distances of almost 100 nm at low temperature. The
+corresponding spin diffusion length dspin is estimated around 40 nm.
+Furthermore, we find that the insertion of a SrTiO_{3} tunneling barrier does
+not improve spin injection, likely due to the matching of resistances at the
+interfaces. Our result on dspin may be likely improved, both in terms of
+Cu_{2}O crystalline quality and sub-micrometric morphology and in terms of
+device geometry, indicating that Cu_{2}O is a potential material for efficient
+spin transport in devices based on crystalline oxides.",1004.3201v1
+2010-04-30,Scalability of Atomic-Thin-Body (ATB) Transistors Based on Graphene Nanoribbons,"A general solution for the electrostatic potential in an atomic-thin-body
+(ATB) field-effect transistor geometry is presented. The effective
+electrostatic scaling length, {\lambda}eff, is extracted from the analytical
+model, which cannot be approximated by the lowest order eigenmode as
+traditionally done in SOI-MOSFETs. An empirical equation for the scaling length
+that depends on the geometry parameters is proposed. It is shown that even for
+a thick SiO2 back oxide {\lambda}eff can be improved efficiently by thinner top
+oxide thickness, and to some extent, with high-k dielectrics. The model is then
+applied to self-consistent simulation of graphene nanoribbon (GNR)
+Schottky-barrier field-effect transistors (SB-FETs) at the ballistic limit. In
+the case of GNR SB-FETs, for large {\lambda}eff, the scaling is limited by the
+conventional electrostatic short channel effects (SCEs). On the other hand, for
+small {\lambda}eff, the scaling is limited by direct source-to-drain tunneling.
+A subthreshold swing below 100mV/dec is still possible with a sub-10nm gate
+length in GNR SB-FETs.",1004.5560v1
+2010-06-02,Towards a first-principles chemical engineering: Transport limitations and bistability in in situ CO oxidation at RuO2(110),"We present a first-principles based multiscale modeling approach to
+heterogeneous catalysis that integrates first-principles kinetic Monte Carlo
+simulations of the surface reaction chemistry into a fluid dynamical treatment
+of the macro-scale flow structures in the reactor. The approach is applied to a
+stagnation flow field in front of a single-crystal model catalyst, using the CO
+oxidation at RuO2(110) as representative example. Our simulations show how heat
+and mass transfer effects can readily mask the intrinsic reactivity at
+gas-phase conditions typical for modern in situ experiments. For a range of
+gas-phase conditions we furthermore obtain multiple steady-states that arise
+solely from the coupling of gas-phase transport and surface kinetics. This
+additional complexity needs to be accounted for when aiming to use dedicated in
+situ experiments to establish an atomic-scale understanding of the function of
+heterogeneous catalysts at technologically relevant gas-phase conditions.",1006.0343v1
+2010-06-11,"Superconductivity Above 40 K Observed in a New Iron Arsenide Oxide (Fe2As2)(Ca4(Mg,Ti)3Oy)","A new layered iron arsenide oxide (Fe2As2)(Ca4(Mg,Ti)3Oy) was discovered. Its
+crystal structure is tetragonal with a space group of I4/mmm consisted of the
+anti-fluorite type FeAs layer and blocking layer of triple perovskite cells and
+is identical with (Fe2As2)(Sr4(Sc,Ti)3O8) discovered in our previous study. The
+lattice constants of (Fe2As2)(Ca4(Mg,Ti)3Oy) are a = 3.877 A and c = 33.37 A.
+This compound exhibited bulk superconductivity up to 43 K in susceptibility
+measurement without intentional carrier doping. A resistivity drop was observed
+at ~47 K and zero resistance was achieved at 42 K. These values correspond to
+the second highest Tc among the layered iron-based superconductors after
+REFeAsO system.",1006.2367v2
+2010-06-12,Role of van der Waals bonding in layered oxide: Bulk vanadium pentoxide,"Sparse matter is characterized by regions with low electron density and its
+understanding calls for methods to accurately calculate both the van der Waals
+(vdW) interactions and other bonding. Here we present a first-principles
+density functional theory (DFT) study of a layered oxide (V2O5) bulk structure
+which shows charge voids in between the layers and we highlight the role of the
+vdW forces in building up material cohesion. The result of previous
+first-principles studies involving semilocal approximations to the
+exchange-correlation functional in DFT gave results in good agreement with
+experiments for the two in-plane lattice parameters of the unit cell but
+overestimated the parameter for the stacking direction. To recover the third
+parameter we include the nonlocal (dispersive) vdW interactions through the
+vdW-DF method [Dion et al., Phys. Rev. Lett. 92, 246401 (2004)] testing also
+various choices of exchange flavors. We find that the transferable
+first-principle vdW-DF calculations stabilizes the bulk structure. The vdW-DF
+method gives results in fairly good agreement with experiments for all three
+lattice parameters.",1006.2494v1
+2010-06-24,Visualizing nanoscale electronic band alignment at the La$_{2/3}$Ca$_{1/3}$MnO$_{3}$/Nb:SrTiO$_{3}$ interface,"Cross-sectional scanning tunnelling microscopy and spectroscopy (XSTM/S) were
+used to map out the band alignment across the complex oxide interface of
+La$_{2/3}$Ca$_{1/3}$MnO$_{3}$/Nb-doped SrTiO$_{3}$. By a controlled
+cross-sectional fracturing procedure, unit-cell high steps persist near the
+interface between the thin film and the substrate in the non-cleavable
+perovskite materials. The abrupt changes of the mechanical and electronic
+properties were visualized directly by XSTM/S. Using changes in the DOS as
+probe by STM, the electronic band alignment across the heterointerface was
+mapped out providing a new approach to directly measure the electronic
+properties at complex oxide interfaces.",1006.4886v2
+2010-06-28,Reversible carrier-type transition in gas-sensing oxides and nanostructures,"Despite many important applications of a-Fe2O3 and Fe doped SnO2 in
+semiconductors, catalysis, sensors, clinical diagnosis and treatments, one
+fundamental issue that is crucial to these applications remains theoretically
+equivocal- the reversible carrier-type transition between n- and p-type
+conductivities during gas-sensing operations. Here, we give unambiguous and
+rigorous theoretical analysis in order to explain why and how the oxygen
+vacancies affect the n-type semiconductors, a-Fe2O3 and Fe doped SnO2 in which
+they are both electronically and chemically transformed into a p-type
+semiconductor. Furthermore, this reversible transition also occurs on the oxide
+surfaces during gas-sensing operation due to physisorbed gas molecules (without
+any chemical reaction). We make use of the ionization energy theory and its
+renormalized ionic displacement polarizability functional to reclassify,
+generalize and to explain the concept of carrier-type transition in solids, and
+during gas-sensing operation. The origin of such a transition is associated to
+the change in ionic polarizability and the valence states of cations in the
+presence of (a) oxygen vacancies and (b) physisorped gas molecules.",1006.5304v2
+2010-07-29,Low-energy kink in the nodal dispersion of copper-oxide superconductors: Insights from Dynamical Mean Field Theory,"Motivated by the observation in copper-oxide high-temperature
+superconductors, we investigate the appearance of kinks in the electronic
+dispersion due to coupling to phonons for a system with strong electronic
+repulsion. We study a Hubbard model supplemented by an electron-phonon coupling
+of Holstein type within Dynamical Mean Field Theory (DMFT) utilizing Numerical
+Renormalization Group as impurity solver. Paramagnetic DMFT solutions in the
+presence of large repulsion show a kink only for large values of the
+electron-phonon coupling $\lambda$ or large doping and, contrary to the
+conventional electron-phonon theory, the position of such a kink can be shifted
+to energies larger than the renormalized phonon frequency $\omega_0^r$. When
+including antiferromagnetic correlations we find a stronger effect of the
+electron-phonon interaction on the electronic dispersion due to a cooperative
+effect and a visible kink at $\omega_0^r$, even for smaller $\lambda$. Our
+results provide a scenario of a kink position increasing with doping, which
+could be related to recent photoemission experiments on Bi-based cuprates.",1007.5268v3
+2010-07-30,Thermal Activation and Quantum Field Emission in a Sketch-Based Oxide Nano Transistor,"We report direct measurements of the potential barriers and electronic
+coupling between nanowire segments within a sketch-based oxide nanotransistor
+(SketchFET) device. Near room temperature, switching is governed by thermally
+activation across a potential barrier controlled by the nanowire gate. Below
+T=150 K, a crossover to quantum field emission is observed that is sensitive to
+structural phase transitions in the SrTiO3 layer. This direct measurement of
+the source-drain and gate-drain energy barriers is crucial for the development
+of room-temperature logic and memory elements and low-temperature quantum
+devices.",1007.5468v2
+2010-08-05,The structure of graphite oxide: Investigation of its surface chemical groups,"The structure of graphite oxide (GO) has been systematically studied using
+various tools such as SEM, TEM, XRD, Fourier transform infrared spectroscopy
+(FT-IR), X-ray photoemission spectroscopy (XPS), 13C solid state NMR, and O
+K-edge X-ray absorption near edge structure (XANES). The TEM data reveal that
+GO consists of amorphous and crystalline phases. The XPS data show that some
+carbon atoms have sp3 orbitals and others have sp2 orbitals. The ratio of sp2
+to sp3 bonded carbon atoms decreases as sample preparation times increase. The
+13C solid-state NMR spectra of GO indicate the existence of -OH and -O- groups
+for which peaks appear at 60 and 70 ppm, respectively. FT-IR results
+corroborate these findings. The existence of ketone groups is also implied by
+FT-IR, which is verified by O K-edge XANES and 13C solid-state NMR. We propose
+a new model for GO based on the results; -O-, -OH, and -C=O groups are on the
+surface.",1008.0937v1
+2010-08-11,Scale-free structural organization of oxygen interstitials in La2CuO4+y,"It is well known that the microstructures of the transition-metal oxides
+(refs 1-3), including the high-transition-temperature (high-Tc) copper oxide
+superconductors (refs 4-7), are complex. This is particularly so when there are
+oxygen interstitials or vacancies (ref.8), which influence the bulk properties.
+For example, the oxygen interstitials in the spacer layers separating the
+superconducting CuO2 planes undergo ordering phenomena in Sr(2)O(1+y)CuO(2)
+(ref. 9), YBa(2)Cu(3)O(6+y) (ref. 10) and La(2)CuO(4+y) (refs 11-15) that
+induce enhancements in the transition temperatures with no changes in hole
+concentrations. It is also known that complex systems often have a
+scale-invariant structural organization16, but hitherto none had been found in
+high-Tc materials. Here we report that the ordering of oxygen interstitials in
+the La(2)O(2+y) spacer layers of La(2)CuO(4+y) high-Tc superconductors is
+characterized by a fractal distribution up to a maximum limiting size of 400
+microns. Intriguingly, these fractal distributions of dopants seem to enhance
+superconductivity at high temperature.",1008.2015v2
+2010-08-27,Flow boiling of water on nanocoated surfaces in a microchannel,"Experiments were performed to study the effects of surface wettability on
+flow boiling of water at atmospheric pressure. The test channel is a single
+rectangular channel 0.5 mm high, 5 mm wide and 180 mm long. The mass flux was
+set at 100 kg/m2 s and the base heat flux varied from 30 to 80 kW/m2. Water
+enters the test channel under subcooled conditions. The samples are silicone
+oxide (SiOx), titanium (Ti), diamond-like carbon (DLC) and carbon-doped silicon
+oxide (SiOC) surfaces with static contact angles of 26{\deg}, 49{\deg},
+63{\deg} and 103{\deg}, respectively. The results show significant impacts of
+surface wettability on heat transfer coefficient.",1008.4696v1
+2010-08-31,"Size, oxidation, and strain in small Si/SiO2 nanocrystals","The structural, electronic and optical properties of Si nanocrystals of
+different size and shape, passivated with hydrogens, OH groups, or embedded in
+a SiO2 matrix are studied. The comparison between the embedded and free,
+suspended nanocrystals shows that the silica matrix produces a strain on the
+embedded NCs, that contributes to determine the band gap value. By including
+the strain on the hydroxided nanocrystals we are able to reproduce the
+electronic and optical properties of the full Si/SiO2 systems. Moreover we
+found that, while the quantum confinement dominates in the hydrogenated
+nanocrystals of all sizes, the behaviour of hydroxided and embedded
+nanocrystals strongly depends on the interface oxidation degree, in particular
+for diameters below 2 nm. Here, the proportion of NC atoms at the Si/SiO2
+interface becomes relevant, producing surface-related states that may affect
+the quantum confinement appearing as inner band gap states and then drastically
+changing the optical response of the system.",1008.5272v1
+2010-09-02,Superconducting and Structural Transitions in the β-Pyrochlore Oxide KOs2O6 under High Pressure,"Rattling-induced superconductivity in the {\beta}-pyrochlore oxide KOs2O6 is
+investigated under high pressure up to 5 GPa. Resistivity measurements in a
+high-quality single crystal reveal a gradual decrease in the superconducting
+transition temperature Tc from 9.7 K at 1.0 GPa to 6.5 K at 3.5 GPa, followed
+by a sudden drop to 3.3 K at 3.6 GPa. Powder X-ray diffraction experiments show
+a structural transition from cubic to monoclinic or triclinic at a similar
+pressure. The sudden drop in Tc is ascribed to this structural tran-sition, by
+which an enhancement in Tc due to a strong electron-rattler interaction present
+in the low-pressure cubic phase is abrogated as the rattling of the K ion is
+completely suppressed or weakened in the high-pressure phase of reduced
+symmetry. In addition, we find two anomalies in the temperature dependence of
+resistivity in the low-pressure phase, which may be due to subtle changes in
+rattling vibration.",1009.0355v1
+2010-09-09,Thermal Activation and Quantum Field Emission in a Sketch-Based Oxide Nano Transistor,"The interface between polar LaAlO3 and non-polar SrTiO3 exhibits a remarkable
+variety of electronic behavior associated with the formation of an interfacial
+quasi-two-dimensional electron gas (q-2DEG). By ""sketching"" patterns of charge
+on the top LaAlO3 surface, the LaAlO3/SrTiO3 interface conductance can be
+controlled with near-atomic spatial resolution. Using this technique, a
+sketch-based oxide nanotransistor (SketchFET) was demonstrated with a minimum
+feature size of just two nanometers. Here we report direct measurements of the
+potential barriers and electronic coupling between nanowire segments within a
+SketchFET device. Near room temperature, switching is governed by thermally
+activated field emission from the nanowire gate. Below T=150 K, a crossover to
+quantum field emission is observed that is sensitive to structural phase
+transitions in the SrTiO3 layer. This direct measurement of the source-drain
+and gate-drain energy barriers is crucial for the development of
+room-temperature logic and memory elements and low-temperature quantum devices.",1009.1893v1
+2010-10-05,Interatomic potentials for mixed oxide (MOX) nuclear fuels,"We extend our recently developed interatomic potentials for UO_{2} to the
+mixed oxide fuel system (U,Pu,Np)O_{2}. We do so by fitting against an
+extensive database of ab initio results as well as to experimental
+measurements. The applicability of these interactions to a variety of mixed
+environments beyond the fitting domain is also assessed. The employed formalism
+makes these potentials applicable across all interatomic distances without the
+need for any ambiguous splining to the well-established short-range
+Ziegler-Biersack-Littmark universal pair potential. We therefore expect these
+to be reliable potentials for carrying out damage simulations (and Molecular
+Dynamics simulations in general) in nuclear fuels of varying compositions for
+all relevant atomic collision energies.",1010.0976v1
+2010-10-11,Restoring the electrical conductivity of graphene oxide films by UV light induced oxygen desorption,"We report a chemical free method for the reduction of graphene oxide (GO)
+thin films. It was observed how for GO films annealed in air the oxygen species
+desorb from the GO surface upon exposure to UV light and how the surface
+resistivity of such deoxygenated GO films decreases with increasing the
+exposure to the UV light. The obtained results open a clean as well as easy
+route for the integration of GO based materials into optoelectronic devices.",1010.2108v4
+2010-10-23,Silicon Oxide is a Non-Innocent Surface for Molecular Electronics and Nanoelectronics Studies,"Silicon oxide (SiOx) has been widely used in many electronic systems as a
+supportive and insulating medium. Here we demonstrate various electrical
+phenomena such as negative differential resistance, resistive switching and
+current hysteresis intrinsic to a thin layer of SiOx. These behaviors can
+largely mimic numerous electrical phenomena observed in molecules and other
+nanomaterials, suggesting that substantial caution should be paid when studying
+conduction in electronic systems with SiOx as a component. The actual switching
+can be the result of SiOx and not the presumed molecular or nanomaterial
+component. These electrical properties and the underlying mechanisms are
+discussed in detail.",1010.4853v1
+2010-10-29,Double quantum dot with tunable coupling in an enhancement-mode silicon metal-oxide semiconductor device with lateral geometry,"We present transport measurements of a tunable silicon
+metal-oxide-semiconductor double quantum dot device with lateral geometry.
+Experimentally extracted gate-to-dot capacitances show that the device is
+largely symmetric under the gate voltages applied. Intriguingly, these gate
+voltages themselves are not symmetric. Comparison with numerical simulations
+indicates that the applied gate voltages serve to offset an intrinsic asymmetry
+in the physical device. We also show a transition from a large single dot to
+two well isolated coupled dots, where the central gate of the device is used to
+controllably tune the interdot coupling.",1011.0034v1
+2010-11-12,Identification of the major cause of endemically poor mobilities in SiC/SiO2 structures,"Materials with good carrier mobilities are desired for device applications,
+but in real devices the mobilities are usually limited by the presence of
+interfaces and contacts. Mobility degradation at semiconductor-dielectric
+interfaces is generally attributed to defects at the interface or inside the
+dielectric, as is the case in Si/SiO2 structures, where processing does not
+introduce detrimental defects in the semiconductor. In the case of SiC/SiO2
+structures, a decade of research focused on reducing or passivating interface
+and oxide defects, but the low mobilities have persisted. By invoking
+theoretical results and available experimental evidence, we show that thermal
+oxidation generates carbon di-interstitial defects inside the semiconductor
+substrate and that they are a major cause of the poor mobility in SiC/SiO2
+structures.",1011.2820v1
+2010-11-23,Design of a low band gap oxide ferroelectric: Bi$_6$Ti$_4$O$_{17}$,"A strategy for obtaining low band gap oxide ferroelectrics based on charge
+imbalance is described and illustrated by first principles studies of the
+hypothetical compound Bi$_6$Ti$_4$O$_{17}$, which is an alternate stacking of
+the ferroelectric Bi$_4$Ti$_3$O$_{12}$. We find that this compound is
+ferroelectric, similar to Bi$_4$Ti$_3$O$_{12}$ although with a reduced
+polarization. Importantly, calculations of the electronic structure with the
+recently developed functional of Tran and Blaha yield a much reduced band gap
+of 1.83 eV for this material compared to Bi$_4$Ti$_3$O$_{12}$. Therefore,
+Bi$_6$Ti$_4$O$_{17}$ is predicted to be a low band gap ferroelectric material.",1011.5089v2
+2010-11-24,A model for the degradation of polyimides due to oxidation,"Polyimides, due to their superior mechanical behavior at high temperatures,
+are used in a variety of applications that include aerospace, automobile and
+electronic packaging industries, as matrices for composites, as adhesives etc.
+In this paper, we extend our previous model in [S. Karra, K. R. Rajagopal,
+Modeling the non-linear viscoelastic response of high temperature polyimides,
+Mechanics of Materials, In press, doi:10.1016/j.mechmat.2010.09.006], to
+include oxidative degradation of these high temperature polyimides. Appropriate
+forms for the Helmholtz potential and the rate of dissipation are chosen to
+describe the degradation. The results for a specific boundary value problem,
+using our model compares well with the experimental creep data for PMR-15 resin
+that is aged in air.",1011.5451v1
+2010-12-07,Intrinsic Reliability improvement in Biaxially Strained SiGe p-MOSFETs,"In this letter we not only show improvement in the performance but also in
+the reliability of 30nm thick biaxially strained SiGe (20%Ge) channel on Si
+p-MOSFETs. Compared to Si channel, strained SiGe channel allows larger hole
+mobility ({\mu}h) in the transport direction and alleviates charge flow towards
+the gate oxide. {\mu}h enhancement by 40% in SiGe and 100% in Si-cap SiGe is
+observed compared to the Si hole universal mobility. A ~40% reduction in NBTI
+degradation, gate leakage and flicker noise (1/f) is observed which is
+attributed to a 4% increase in the hole-oxide barrier height ({\phi}) in SiGe.
+Similar field acceleration factor ({\Gamma}) for threshold voltage shift
+({\Delta}VT) and increase in noise ({\Delta}SVG) in Si and SiGe suggests
+identical degradation mechanisms.",1012.1579v2
+2010-12-16,Ab Initio determination of Cu 3d orbital energies in layered copper oxides,"It has long been argued that the minimal model to describe the low-energy
+physics of the high-Tc superconducting cuprates must include copper states of
+other symmetries besides the canonical x2-y2 one, in particular the z2 orbital.
+Experimental and theoretical estimates of the energy splitting of these states
+vary widely. With a novel ab initio quantum chemical computational scheme we
+determine these energies for a range of copper-oxides and -oxyclorides,
+determine trends with the apical Cu-ligand distances and find excellent
+agreement with recent Resonant Inelastic X-ray Scattering measurements,
+available for La2CuO4, Sr2CuO2Cl2, and CaCuO2.",1012.3603v2
+2010-12-17,Halving the Casimir force with conductive oxides: experimental details,"This work is an extended version of a paper published last year in Physical
+Review Letters [S. de Man et al., Phys. Rev. Lett. 103, 040402 (2009)], where
+we presented measurements of the Casimir force between a gold coated sphere and
+a plate coated with either gold or an indium-tin-oxide (ITO) layer. The
+experiment, which was performed in air, showed that ITO is sufficiently
+conducting to prevent charge accumulation, but still transparent enough to
+halve the Casimir attraction when compared to gold. Here, we report all the
+experimental details that, due to the limited space available, were omitted in
+the previous article. We discuss the performance of our setup in terms of
+stability of the calibration procedure and reproducibility of the Casimir force
+measurement. We also introduce and demonstrate a new technique to obtain the
+spring constant of our force sensor. Furthermore, we present a thorough
+description of the experimental method, a comprehensive explanation of data
+elaboration and error analysis, and a complete characterization of the
+dielectric function and of the surface roughness of the samples used in the
+actual experiment.",1012.3831v1
+2010-12-17,First-principles study of phase stability of Gd-doped EuO and EuS,"Phase diagrams of isoelectronic Eu$_{1-x}$Gd$_x$O and Eu$_{1-x}$Gd$_{x}$S
+quasi-binary alloy systems are constructed using first-principles calculations
+combined with the standard cluster expansion approach and Monte-Carlo
+simulations. The oxide system has a wide miscibility gap on the Gd-rich side
+but forms ordered compounds on the Eu-rich side, exhibiting a deep asymmetric
+convex hull in the formation enthalpy diagram. The sulfide system has no stable
+compounds. The large difference in the formation enthalpies of the oxide and
+sulfide compounds is due to the contribution of local lattice relaxation, which
+is sensitive to the anion size. The solubility of Gd in both EuO and EuS is in
+the range of 10-20% at room temperature and quickly increases at higher
+temperatures, indicating that highly doped disordered solid solutions can be
+produced without the precipitation of secondary phases. We also predict that
+rocksalt GdO can be stabilized under appropriate experimental conditions.",1012.4026v1
+2011-01-17,Reduction of a Single Layer Graphene Oxide Film on Pt(111),"Graphene oxide (GO) is one of chemically modified graphenes and has been
+extensively studied worldwide. A monolayer sheet of GO which is chemically
+produced in solution can be deposited on various substrates. We have proved
+that use of graphite powder with a large grain size enables preparation of a
+single layer GO film that is larger than 100 micrometers easily and
+reproducibly. If it is possible to reduce the GO film completely, one can
+obtain graphene without mechanical exfoliation. However, the reduction methods
+employed so far have been insufficient to remove oxygen or to restore the long
+range order in graphene lattice. In the present work we annealed the GO sheet
+which was placed on Pt(111) in ultrahigh vacuum. The STM observation of the
+annealed specimen reveals that a honeycomb lattice appears together with moire
+structures of long range ordering. The XPS result indicated complete removal of
+oxygen from the GO sheet. These results would open a new way to synthesize a
+high quality graphene film, which replaces the conventional CVD method.",1101.3117v1
+2011-02-08,Conductive Atomic Force Microscopy of Chemically Synthesized Graphene Oxide and Interlayer Conduction,"Graphene oxide (GO) is one of chemically modified graphenes and has been
+extensively investigated worldwide. A monolayer sheet of GO can be chemically
+produced in solution and it has been expected to be adaptable to a wide variety
+of applications. Most of works have focused on fabrication and reduction
+processes of GO, while its intrinsic property has not been explored in detail.
+We have succeeded in fabricating large scale GO nanosheets reproducibly. In the
+present work, we observed GO nanosheets by conductive atomic force microscopy.
+The current image is useful to monitor the GO thickness as well as wrinkles and
+folds in the nanosheet with high contrast. In addition to the current images,
+local I-V characteristics of the GO sheet were measured with the conductive
+cantilever. Based on the applied electric filed dependence, the conduction
+normal to the GO sheet could be described in terms of Poole Frenkel emission
+mechanism and the relative permittivity of GO is evaluated to be 4.8.",1102.1515v3
+2011-02-15,Predicted Oxidation of CO Catalyzed by Au Nanoclusters on a Thin Defect-Free MgO Film Supported on a Mo(100) Surface,"Here we show results of first-principles investigations aiming at tuning and
+controlling the catalytic activity of gold nanoclusters through the design of
+the underlying support. We show that gold clusters adsorbed on a very thin (2
+layers) defect-free MgO film which is itself supported on Mo(100), may serve as
+model catalysts for the low-barrier oxidation of CO. The origin of the emergent
+activity of the nanoclusters is a dimensionality crossover of the adsorbed gold
+clusters, from inactive three-dimensional (3D) optimal structures on thick MgO
+films, to catalytically active 2D ones for sufficiently thin MgO films (less
+then 1nm in thickness) supported on Mo(100).",1102.3011v1
+2011-03-03,Two-probe study of hot carriers in reduced graphene oxide,"The energy relaxation of carriers in reduced graphene oxide thin films is
+studied using optical pump-probe spectroscopy with two probes of different
+colors. We measure the time difference between peaks of the carrier density at
+each probing energy by measuring a time-resolved differential transmission and
+find that the carrier density at the lower probing energy peaks later than that
+at the higher probing energy. Also, we find that the peak time for the lower
+probing energy shifts from about 92 to 37 fs after the higher probing energy
+peak as the carrier density is increased from 1.5E12 to 3E13 per square
+centimeter, while no noticeable shift is observed in that for the higher
+probing energy. Assuming the carriers rapidly thermalize after excitation, this
+indicates that the optical phonon emission time decreases from about 50 to
+about 20 fs and the energy relaxation rate increases from 4 to 10 meV/fs. The
+observed density dependence is inconsistent with the phonon bottleneck effect.",1103.0728v1
+2011-03-04,Voltage bias induced modification of all oxide Pr0.5Ca0.5MnO3/SrTi0.95Nb.05O3 junctions,"In this paper we report what happens to a pristine oxide junction
+Pr0.5Ca0.5MnO3/SrTi0.95Nb.05O3 (PCMO/Nb:STO), when it is subjected to cycling
+of voltage bias of moderate value ({\pm}4V). It is found that the initial
+cycling leads to formation of a permanent state of lower resistance where the
+lower resistance arises predominantly due to development of a shunt across the
+device film (PCMO). On successive voltage cycling with increasing magnitude,
+this state transforms into states of successive lower resistance that can be
+transformed back to the initial stable state on cycling to below a certain
+bias. A simple model based on p-n junction with shunt has been used to obtain
+information on the change of the junction on voltage cycling. It has been shown
+that the observation can be explained if the voltage cycling leads to lowering
+of barrier at the interface and also reduction in series resistance. It is
+suggested that this lowering can be related to the migration of oxygen ions and
+vacancies at the junction region. Cross-sectional imaging of the junction shows
+formation of permanent filamentary bridges across the thickness of the PCMO
+after the pristine p-n junction is first taken through a voltage cycle, which
+would explain appearance of a finite shunt across the p-n junction.",1103.0884v1
+2011-03-19,Field emission from atomically thin edges of reduced graphene oxide,"Point sources exhibit low threshold electron emission due to local field
+enhancement at the tip. The development and implementation of tip emitters have
+been hampered by the need to position them sufficiently apart to achieve field
+enhancement, limiting the number of emission sites and therefore the overall
+current. Here we report low threshold field (< 0.1V/um) emission of multiple
+electron beams from atomically thin edges of reduced graphene oxide (rGO).
+Field emission microscopy (FEM) measurements show evidence for interference
+from emission sites that are separated by a few nanometers, suggesting that the
+emitted electron beams may be coherent. Based on our high-resolution
+transmission electron microscopy, infrared spectroscopy and simulation results,
+field emission from the rGO edge is attributed to a stable and unique
+aggregation of oxygen groups in the form of cyclic edge ethers. Such closely
+spaced electron beams from rGO offer prospects for novel applications and
+understanding the physics of linear electron sources.",1103.3798v1
+2011-04-04,Epitaxial growth of FeSe$_{0.5}$Te$_{0.5}$ thin films on CaF$_2$ substrates with high critical current density,"In-situ epitaxial growth of FeSe$_{0.5}$Te$_{0.5}$ thin films is demonstrated
+on a non-oxide substrate CaF$_2$. Structural analysis reveals that compressive
+stress is moderately added to 36-nm thick FeSe$_{0.5}$Te$_{0.5}$, which pushes
+up the critical temperature above 15 K, showing higher values than that of bulk
+crystals. Critical current density at $T$ = 4.5 K reaches 5.9 x 10$^4$
+Acm$^{-2}$ at $\mu_0H$ = 10 T, and 4.2 x 10$^4$ Acm$^{-2}$ at $\mu_0H$ = 14 T.
+These results indicate that fluoride substrates have high potential for the
+growth of iron-based superconductors in comparison with popular oxide
+substrates.",1104.0477v2
+2011-04-18,"Electronic band structure and inter-atomic bonding in layered 1111-like Th-based pnictide oxides ThCuPO, ThCuAsO, ThAgPO, and ThAgAsO from first principles calculations","First-principles FLAPW-GGA band structure calculations were employed to
+examine the structural, electronic properties and the chemical bonding picture
+for four ZrCuSiAs-like Th-based quaternary pnictide oxides ThCuPO, ThCuAsO,
+ThAgPO, and ThAgAsO. These compounds were found to be semimetals and may be
+viewed as ""intermediate"" systems between two main isostructural groups of
+superconducting and semiconducting 1111 phases. The Th 5f states participate
+actively in the formation of valence bands and the Th 5f states for ThMPnO
+phases are itinerant and partially occupied. We found also that the bonding
+picture in ThMPnO phases can be classified as a high-anisotropic mixture of
+ionic and covalent contributions: inside [Th2O2] and [M2Pn2] blocks, mixed
+covalent-ionic bonds take place, whereas between the adjacent [Th2O2]/[M2Pn2]
+blocks, ionic bonds emerge owing to [Th2O2] \to [M2Pn2] charge transfer.",1104.3434v1
+2011-05-19,Electron-Spin Excitation Coupling in an Electron Doped Copper Oxide Superconductor,"High-temperature (high-Tc) superconductivity in the copper oxides arises from
+electron or hole doping of their antiferromagnetic (AF) insulating parent
+compounds. The evolution of the AF phase with doping and its spatial
+coexistence with superconductivity are governed by the nature of charge and
+spin correlations and provide clues to the mechanism of high-Tc
+superconductivity. Here we use a combined neutron scattering and scanning
+tunneling spectroscopy (STS) to study the Tc evolution of electron-doped
+superconducting Pr0.88LaCe0.12CuO4-delta obtained through the oxygen annealing
+process. We find that spin excitations detected by neutron scattering have two
+distinct modes that evolve with Tc in a remarkably similar fashion to the
+electron tunneling modes in STS. These results demonstrate that
+antiferromagnetism and superconductivity compete locally and coexist spatially
+on nanometer length scales, and the dominant electron-boson coupling at low
+energies originates from the electron-spin excitations.",1105.3987v1
+2011-06-04,Janus-faced influence of the Hund's rule coupling in strongly correlated materials,"We show that in multi-band metals the correlations are strongly affected by
+the Hund's rule coupling, which depending on the filling promotes metallic,
+insulating or bad-metallic behavior. The quasiparticle coherence and the
+proximity to a Mott insulator are influenced distinctly and, away from single-
+and half-filling, in opposite ways. A strongly correlated bad-metal far from a
+Mott phase is found there. We propose a concise classification of 3d and 4d
+transition-metal oxides within which the ubiquitous occurrence of strong
+correlations in Ru- and Cr-based oxides, as well as the recently measured high
+N\'eel temperatures in Tc-based perovskites are naturally explained.",1106.0815v1
+2011-06-16,"Reverse Monte Carlo neutron scattering study of the ""ordered-ice"" oxide pyrochlore Pb2Ru2O6.5","We employ high-resolution total neutron scattering in conjunction with
+reverse Monte Carlo simulations to examine, in a detailed and unbiased manner,
+the crystal structure of the vacancy-ordered oxide pyrochlore Pb2Ru2O6.5 in
+light of its structural analogy with proton-ordering in the structures of ice.
+We find that the vacancy and the O' ion are completely ordered, and that the
+average structure in the F43m space group describes the vacancy ordering
+precisely. We complement these results with an examination of the Pb2+ lone
+pair network using density functional electronic structure calculations, and a
+comparison of the low-temperature lattice-only heat capacity of Pb2Ru2O6.5 with
+that of other related pyrochlores.",1106.3257v1
+2011-06-21,Process Optimization and Downscaling of a Single Electron Single Dot Memory,"This paper presents the process optimization of a single-electron nanoflash
+electron memory. Self-aligned single dot memory structures have been fabricated
+using a wet anisotropic oxidation of a silicon nanowire. One of the main issue
+was to clarify the process conditions for the dot formation. Based on the
+process modeling, the influence of various parameters (oxidation temperature,
+nanowire shape) has been investigated. The necessity of a sharp compromise
+between these different parameters to ensure the presence of the memory dot has
+been established. In order to propose an aggressive memory cell, the
+downscaling of the device has been carefully studied. Scaling rules show that
+the size of the original device could be reduced by a factor of 2. This point
+has been previously confirmed by the realization of single-electron memory
+devices.",1106.4289v1
+2011-06-21,Interface engineering of quantum Hall effects in digital transition metal oxide heterostructures,"Topological insulators are characterized by a nontrivial band topology driven
+by the spin-orbit coupling. To fully explore the fundamental science and
+application of topological insulators, material realization is indispensable.
+Here we predict, based on tight-binding modeling and first-principles
+calculations, that bilayers of perovskite-type transition-metal oxides grown
+along the [111] crystallographic axis are potential candidates for
+two-dimensional topological insulators. The topological band structure of these
+materials can be fine-tuned by changing dopant ions, substrates, and external
+gate voltages. We predict that LaAuO$_3$ bilayers have a
+topologically-nontrivial energy gap of about 0.15 eV, which is sufficiently
+large to realize the quantum spin-Hall effect at room temperature. Intriguing
+phenomena, such as fractional quantum Hall effect, associated with the
+nearly-flat topologically-nontrivial bands found in $e_g$ systems are also
+discussed.",1106.4296v4
+2011-06-30,Controlled fabrication of single-walled carbon nanotube electrodes by electron-beam-induced oxidation,"The fabrication of metallic single-walled carbon nanotube electrodes
+separated by gaps of typically 20nm width by electron-beam-induced oxidation is
+studied within an active device configuration. The tube conductance is measured
+continuously during the process. The experiment provides a statistical
+evaluation of gap sizes as well as the electron dose needed for gap formation.
+Also, the ability to precisely cut many carbon nanotubes in parallel is
+demonstrated.",1106.6274v1
+2011-07-01,Graphene-Wrapped Sulfur Particles as a Rechargeable Lithium-Sulfur-Battery Cathode Material with High Capacity and Cycling Stability,"We report the synthesis of a graphene-sulfur composite material by wrapping
+polyethyleneglycol (PEG) coated submicron sulfur particles with mildly oxidized
+graphene oxide sheets decorated by carbon black nanoparticles. The PEG and
+graphene coating layers are important to accommodating volume expansion of the
+coated sulfur particles during discharge, trapping soluble polysulfide
+intermediates and rendering the sulfur particles electrically conducting. The
+resulting graphene-sulfur composite showed high and stable specific capacities
+up to ~600mAh/g over more than 100 cycles, representing a promising cathode
+material for rechargeable lithium batteries with high energy density.",1107.0109v1
+2011-07-07,Reduced effective spin-orbital degeneracy and spin-orbital ordering in paramagnetic transition metal oxides: Sr2IrO4 vs. Sr2RhO4,"We discuss the notions of spin-orbital polarization and ordering in
+paramagnetic materials, and address their consequences in transition metal
+oxides. Extending the combined density functional and dynamical mean field
+theory scheme to the case of materials with large spin-orbit interactions, we
+investigate the electronic excitations of the paramagnetic phases of Sr2IrO4
+and Sr2RhO4. We show that the interplay of spin-orbit interactions, structural
+distortions and Coulomb interactions suppresses spin-orbital fluctuations. As a
+result, the room temperature phase of Sr2IrO4 is a paramagnetic spin-orbitally
+ordered Mott insulator. In Sr2RhO4, the effective spin-orbital degeneracy is
+reduced, but the material remains metallic, due to both, smaller spin-orbit and
+smaller Coulomb interactions. We find excellent agreement of our ab-initio
+calculations for Sr2RhO4 with angle-resolved photoemission, and make
+predictions for spectra of the paramagnetic phase of Sr2IrO4.",1107.1371v1
+2011-07-11,New Indivisible Geoscience Paradigm,"Earth's interior, I posit, is like one of the rare, oxygen-starved ""enstatite
+chondrite"" meteorites (and unlike a more-oxidized ""ordinary chondrite"" as has
+been believed for seventy years). Laboratory-analyzed enstatite-chondrite
+samples are comparable to having-in-hand impossibleto- gather deep-Earth
+samples. Enstatite-chondrite formation in oxygen-starved conditions caused
+oxygen-loving elements to occur, in part, as non-oxides in their iron-alloy.
+Observations, consistent with solar abundance and behavior of chemical
+elements, lead me to a new interpretation of: (1) Earth's early formation as a
+Jupiter-like gas-giant, (2) its decompressionpowered surface geology, (3)
+Earth's internal composition, and (4) a natural, planetocentric nuclear-fission
+reactor as source of both the geomagnetic field and energy channeled to surface
+""hot-spots"". I present a unified vision of Earth formation and concomitant
+dynamics that explains in a logical and causally related way: (1) fluid
+Earth-core formation without wholeplanet melting, and (2) the myriad
+measurements and observations, previously attributed to ""plate tectonics"", but
+without necessitating mantle convection.",1107.2149v1
+2011-07-15,Orbital degeneracy and Mott transition in Mo pyrochlore oxides,"We present our theoretical results on an effective two-band double-exchange
+model on a pyrochlore lattice for understanding intricate phase competition in
+Mo pyrochlore oxides. The model includes the twofold degeneracy of $e_g'$
+orbitals under trigonal field splitting, the interorbital Coulomb repulsion,
+the Hund's-rule coupling between itinerant $e_g'$ electrons and localized
+$a_{1g}$ spins, and the superexchange antiferromagnetic interaction between the
+$a_{1g}$ spins. By Monte Carlo simulation with treating the Coulomb repulsion
+at an unrestricted-type mean-field level, we obtain the low-temperature phase
+diagram as functions of the Coulomb repulsion and the superexchange
+interaction. The results include four dominant phases with characteristic spin
+and orbital orders and the metal-insulator transitions among them. The
+insulating region is characterized by a `ferro'-type orbital ordering of the
+$e_g'$ orbitals along the local $<111>$ axis, irrespective of the spin
+ordering.",1107.2986v1
+2011-08-11,Co3O4 Nanocrystals on Graphene as a Synergistic Catalyst for Oxygen Reduction Reaction,"Catalysts for oxygen reduction and evolution reactions are at the heart of
+key renewable energy technologies including fuel cells and water splitting.
+Despite tremendous efforts, developing oxygen electrode catalysts with high
+activity at low costs remains a grand challenge. Here, we report a hybrid
+material of Co3O4 nanocrystals grown on reduced graphene oxide (GO) as a
+high-performance bi-functional catalyst for oxygen reduction reaction (ORR) and
+oxygen evolution reaction (OER). While Co3O4 or graphene oxide alone has little
+catalytic activity, their hybrid exhibits an unexpected, surprisingly high ORR
+activity that is further enhanced by nitrogen-doping of graphene. The
+Co3O4/N-doped graphene hybrid exhibits similar catalytic activity but superior
+stability to Pt in alkaline solutions. The same hybrid is also highly active
+for OER, making it a high performance non-precious metal based bi-catalyst for
+both ORR and OER. The unusual catalytic activity arises from synergetic
+chemical coupling effects between Co3O4 and graphene.",1108.2331v1
+2011-08-10,The role of the coating and aggregation state in the interactions between iron oxide nanoparticles and 3T3 fibroblasts,"Recent nanotoxicity studies revealed that the physico-chemical
+characteristics of engineered nanomaterials play an important role in the
+interactions with living cells. Here, we report on the toxicity and uptake of
+the iron oxide sub-10 nm nanoparticles by NIH/3T3 mouse fibroblasts. Coating
+strategies include low-molecular weight ligands (citric acid) and polymers
+(poly(acrylic acid), MW = 2000 g mol-1). We find that most particles were
+biocompatible, as exposed cells remained 100% viable relative to controls. The
+strong uptake shown by the citrate-coated particles is related to the
+destabilization of the dispersions in the cell culture medium and their
+sedimentation down to the cell membranes.",1108.2395v1
+2011-08-16,Investigation of the Novel Attributes of a Dual Material Gate Nanoscale Tunnel Field Effect Transistor,"In this paper, we propose the application of a Dual Material Gate (DMG) in a
+Tunnel Field Effect Transistor (TFET) to simultaneously optimize the
+on-current, the off-current and the threshold voltage, and also improve the
+average subthreshold slope, the nature of the output characteristics and the
+immunity against the DIBL effects. We demonstrate that if appropriate
+work-functions are chosen for the gate materials on the source side and the
+drain side, the tunnel field effect transistor shows a significantly improved
+performance. We apply the technique of DMG in a Strained Double Gate Tunnel
+Field Effect Transistor with a high-k gate dielectric to show an overall
+improvement in the characteristics of the device along with achieving a good
+on-current and an excellent average subthreshold slope. The results show that
+the DMG technique can be applied to TFETs with different channel materials,
+channel lengths, gate-oxide materials, gate-oxide thicknesses and power supply
+levels to achieve significant gains in the overall device characteristics.",1108.3148v1
+2011-08-25,Dealloying of Platinum-Aluminum Thin Films Part II. Electrode Performance,"Highly porous Pt/Al thin film electrodes on yttria stabilized zirconia
+electrolytes were prepared by dealloying of co-sputtered Pt/Al films. The
+oxygen reduction capability of the resulting electrodes was analyzed in a solid
+oxide fuel cell setup at elevated temperatures. During initial heating to 523 K
+exceptionally high performances compared to conventional Pt thin film
+electrodes were measured. This results from the high internal surface area and
+large three phase boundary length obtained by the dealloying process. Exposure
+to elevated temperatures of 673 K or 873 K gave rise to degradation of the
+electrode performance, which was primarily attributed to the oxidation of
+remaining Al in the thin films.",1108.5132v2
+2011-09-06,Effects of inert species in the gas phase in a model for the catalytic oxidation of CO,"We study by kinetic Monte Carlo simulations the catalytic oxidation of carbon
+monoxide on a surface in the presence of contaminants in the gas phase. The
+process is simulated by a Ziff-Gulari-Barshad (ZGB) model that has been
+modified to include the effect of the contaminants and to eliminate the
+unphysical oxygen-poisoned phase. The impurities can adsorb and desorb on the
+surface, but otherwise remain inert. We find that, if the impurities can not
+desorb, no matter how small their proportion in the gas mixture, the first
+order transition and the reactive window that characterize the ZGB model
+disappear. The coverages become continuous, and once the surface has reached a
+steady state there is no production of CO$_2$. This is quite different from the
+behavior of a system in which the surface presents a fixed percentage of
+impurities. When the contaminants are allowed to desorb, the reactive window
+appears again, and disappears at a value that depends on the proportion of
+contaminants in the gas and on their desorption rate.",1109.1315v2
+2011-09-12,Electrical Properties of Atomic Layer Deposited Aluminum Oxide on Gallium Nitride,"We report on our investigation of the electrical properties of
+metal/Al2O3/GaN metal-insulator-semiconductor (MIS) capacitors. We determined
+the conduction band offset and interface charge density of the alumina/GaN
+interface by analyzing capacitance-voltage characteristics of atomic layer
+deposited Al2O3 films on GaN substrates. The conduction band offset at the
+Al2O3/GaN interface was calculated to be 2.13 eV, in agreement with theoretical
+predications. A non-zero field of 0.93 MV/cm in the oxide under flat-band
+conditions in the GaN was inferred, which we attribute to a fixed net positive
+charge density of magnitude 4.60x1012 cm-2 at the Al2O3/GaN interface. We
+provide hypotheses to explain the origin of this charge by analyzing the energy
+band line-up.",1109.2566v1
+2011-09-16,"Verification, Validation and Testing of Kinetic Mechanisms of Hydrogen Combustion in Fluid Dynamic Computations","A one-step, a two-step, an abridged, a skeletal and four detailed kinetic
+schemes of hydrogen oxidation have been tested. A new skeletal kinetic scheme
+of hydrogen oxidation has been developed. The CFD calculations were carried out
+using ANSYS CFX software. Ignition delay times and speeds of flames were
+derived from the computational results. The computational data obtained using
+ANSYS CFX and CHEMKIN, and experimental data were compared. The precision,
+reliability, and range of validity of the kinetic schemes in CFD simulations
+were estimated. The impact of kinetic scheme on the results of computations was
+discussed. The relationship between grid spacing, timestep, accuracy, and
+computational cost were analyzed.",1109.3563v2
+2011-09-22,Microscopic model for the ferroelectric field effect in oxide heterostructures,"A microscopic model Hamiltonian for the ferroelectric field effect is
+introduced for the study of oxide heterostructures with ferroelectric
+components. The long-range Coulomb interaction is incorporated as an
+electrostatic potential, solved self-consistently together with the charge
+distribution. A generic double-exchange system is used as the conducting
+channel, epitaxially attached to the ferroelectric gate. The observed
+ferroelectric screening effect, namely the charge accumulation/depletion near
+the interface, is shown to drive interfacial phase transitions that give rise
+to robust magnetoelectric responses and bipolar resistive switching, in
+qualitative agreement with previous density functional theory calculations. The
+model can be easily adapted to other materials by modifying the Hamiltonian of
+the conducting channel, and it is useful in simulating ferroelectric field
+effect devices particularly those involving strongly correlated electronic
+components where ab-initio techniques are difficult to apply.",1109.4791v1
+2011-09-22,Universal exchange-driven phonon splitting in antiferromagnets,"We report a linear dependence of the phonon splitting \Delta\omega on the
+non-dominant exchange coupling constant J_{nd} in the antiferromagnetic
+transition-metal monoxides MnO, FeO, CoO, NiO, and in the frustrated
+antiferromagnetic oxide spinels CdCr2O4, MgCr2O4, and ZnCr2O4. It directly
+confirms the theoretical prediction of an exchange induced splitting of the
+zone-centre optical phonon for the monoxides and explains the magnitude and the
+change of sign of the phonon splitting on changing the sign of the non-dominant
+exchange also in the frustrated oxide spinels. The experimentally found linear
+relation \hbar\Delta\omega = \beta J_{nd} S^2 with slope \beta = 3.7 describes
+the splitting for both systems and agrees with the observations in the
+antiferromagnets KCoF3 and KNiF3 with perovskite structure and negligible
+next-nearest neighbour coupling. The common behavior found for very different
+classes of cubic antiferromagnets suggests a universal dependence of the
+exchange-induced phonon splitting at the antiferromagnetic transition on the
+non-dominant exchange coupling.",1109.4809v2
+2011-09-26,Superconductivity and Rattling under High Pressure in the beta-Pyrochlore Oxide RbOs2O6,"Rattling-induced superconductivity in the beta-pyrochlore oxide RbOs2O6 is
+investigated under high pressures up to 6 GPa. Resistivity measurements in a
+high-quality single crystal show that the superconducting transition
+temperature Tc increases gradually from 6.3 K at ambient pressure to 8.8 K at
+3.5 GPa, surprisingly remains almost constant at 8.8 \pm 0.1 K in a wide
+pressure range between 3.5 (Po) and 4.8 GPa, and suddenly drops to 6.3 K at Ps
+= 4.9 GPa, followed by a gradual decrease with further pressure increase. Two
+anomalies in the temperature dependence of the normal-state resistivity are
+observed at Po < P < Ps and P > Ps, revealing the presence of two high-pressure
+phases corresponding to the changes in Tc. The rattling of the Rb ion inside a
+cage made of Os and O atoms may be slightly and seriously modified in these
+high-pressure phases that probably have cages of reduced symmetry,
+respectively, so that electron-rattler interactions that govern the
+superconducting and transport properties of beta-RbOs2O6 are significantly
+affected.",1109.5422v1
+2011-10-04,Imaging Oxygen Defects and their Motion at a Manganite Surface,"Manganites are technologically important materials, used widely as solid
+oxide fuel cell cathodes: they have also been shown to exhibit
+electroresistance. Oxygen bulk diffusion and surface exchange processes are
+critical for catalytic action, and numerous studies of manganites have linked
+electroresistance to electrochemical oxygen migration. Direct imaging of
+individual oxygen defects is needed to underpin understanding of these
+important processes. It is not currently possible to collect the required
+images in the bulk, but scanning tunnelling microscopy could provide such data
+for surfaces. Here we show the first atomic resolution images of oxygen defects
+at a manganite surface. Our experiments also reveal defect dynamics, including
+oxygen adatom migration, vacancy-adatom recombination and adatom bistability.
+Beyond providing an experimental basis for testing models describing the
+microscopics of oxygen migration at transition metal oxide interfaces, our work
+resolves the long-standing puzzle of why scanning tunnelling microscopy is more
+challenging for layered manganites than for cuprates.",1110.0636v1
+2011-10-07,Versatile sputtering technology for Al2O3 gate insulators on graphene,"We report a novel fabrication method of graphene Al2O3 gate insulators based
+on sputtering. Electrical performance of dual-gated mono- and bilayer
+exfoliated graphene devices is presented. Sputtered Al2O3 layers possess
+comparable quality to oxides obtained by atomic layer deposition (ALD) with
+respect to a high relative dielectric constant of about 8, as well as
+low-hysteresis performance and high breakdown voltage. We observe a moderate
+carrier mobility of about 1000 cm2/Vs in graphene and 350 cm2/Vs in its bilayer
+due to increased resonant scattering on atomic scale defects. Most likely this
+originated from the thin Al precursor layer evaporated prior to sputtering the
+Al2O3 gate oxide.",1110.1535v1
+2011-10-10,A Universal Critical Density Underlying the Physics of Electrons at the LaAlO3/SrTiO3 Interface,"The two-dimensional electron system formed at the interface between the
+insulating oxides LaAlO3 and SrTiO3 exhibits ferromagnetism, superconductivity,
+and a wide range of unique magnetotransport properties. A key challenge is to
+find a unified microscopic mechanism that underlies these emergent phenomena.
+Here we show that a universal Lifshitz transition between d-orbitals lies at
+the core of the observed transport phenomena in this system. Our measurements
+find a critical electronic density at which the transport switches from single
+to multiple carriers. This density has a universal value, independent of the
+LaAlO3 thickness and electron mobility. The characteristics of the transition,
+its universality, and its compatibility with spectroscopic measurements
+establish it as a transition between d-orbitals of different symmetries. A
+simple band model, allowing for spin-orbit coupling at the atomic level,
+connects the observed universal transition to a range of reported
+magnetotransport properties. Interestingly, we also find that the maximum of
+the superconducting transition temperature occurs at the same critical
+transition, indicating a possible connection between the two phenomena. Our
+observations demonstrate that orbital degeneracies play an important role in
+the fascinating behavior observed so far in these oxides.",1110.2184v1
+2011-10-14,Negative refraction in Al:ZnO/ZnO metamaterial in the near-infrared,"Noble metals such as gold and silver are the primary metallic building blocks
+of metamaterial devices. Making subwavelength-sized structural elements from
+these metals seriously limits the optical performance of a device, however, and
+complicates the manufacturing process of nearly all metamaterial devices in the
+optical wavelength range. As an alternative to noble metals, we propose to use
+heavily-doped oxide semiconductors that offer both functional and fabrication
+advantages in the near-infrared. In this letter, we report an experimental
+demonstration of negative refraction in a near-infrared metamaterial device
+that is designed and fabricated using aluminum-doped zinc oxide.",1110.3231v1
+2011-10-18,Unintentional F doping of the surface of SrTiO3(001) etched in HF acid -- structure and electronic properties,"We show that the HF acid etch commonly used to prepare SrTiO3(001) for
+heteroepitaxial growth of complex oxides results in a non-negligible level of F
+doping within the terminal surface layer of TiO2. Using a combination of x-ray
+photoelectron spectroscopy and scanned angle x-ray photoelectron diffraction,
+we determine that on average ~13 % of the O anions in the surface layer are
+replaced by F, but that F does not occupy O sites in deeper layers. Despite
+this perturbation to the surface, the Fermi level remains unpinned, and the
+surface-state density, which determines the amount of band bending, is driven
+by factors other than F doping. The presence of F at the STO surface is
+expected to result in lower electron mobilities at complex oxide
+heterojunctions involving STO substrates because of impurity scattering.
+Unintentional F doping can be substantially reduced by replacing the HF-etch
+step with a boil in deionized water, which in conjunction with an oxygen tube
+furnace anneal, leaves the surface flat and TiO2 terminated.",1110.4061v1
+2011-10-25,Atomic-scale visualization of initial growth of homoepitaxial SrTiO3 thin film on an atomically ordered substrate,"The initial homoepitaxial growth of SrTiO3 on a (\surd13\times\surd13) -
+R33.7{\deg}SrTiO3(001) substrate surface, which can be prepared under oxide
+growth conditions, is atomically resolved by scanning tunneling microscopy. The
+identical (\surd13\times\surd13) atomic structure is clearly visualized on the
+deposited SrTiO3 film surface as well as on the substrate. This result
+indicates the transfer of the topmost Ti-rich (\surd13\times\surd13) structure
+to the film surface and atomic-scale coherent epitaxy at the film/substrate
+interface. Such atomically ordered SrTiO3 substrates can be applied to the
+fabrication of atom-by-atom controlled oxide epitaxial films and
+heterostructures.",1110.5410v1
+2011-12-06,Comparison between different oxygen adsorption mechanisms for the catalytic oxidation of CO on a surface,"We study by kinetic Monte Carlo simulations the dynamic behavior of a
+Ziff-Gulari-Barshad (ZGB) model for the catalytic oxidation of CO on a surface.
+It is well known that the ZGB model presents a continuous transition between an
+oxygen poisoned state and a reactive state that it is not observed in nature.
+Based on some experimental results that indicate that the oxygen atoms move
+away from each other upon dissociation at the surface, we modify the standard
+ZGB model by changing the entrance mechanism of the oxygen molecule. We study
+three different ways in which the oxygen atoms can be adsorbed at the surface
+such that the nonphysical continuous phase transition disappears. We calculate
+the phase diagram for the three cases and study the effects of including a CO
+desorption mechanism.",1112.1433v1
+2011-12-12,Realization of the Switching Mechanism in Resistance Random Access Memory (RRAMTM) Devices: Structural and Electronic Properties Affecting Electron Conductivity in Halfnium Oxide-Electrode System through First Principles Calculations,"Resistance Random Access Memory (RRAMTM) device, with its electrically
+induced nanoscale resistive switching capacity, has been gaining considerable
+attention as future non-volatile memory device. Here, we propose a mechanism of
+switching based on oxygen vacancy migration-driven change in electronic
+properties of the transition metal oxide (TMO) film stimulated by set pulse
+voltages. We used density functional theory (DFT)-based calculations to account
+for the effect of oxygen vacancy and its migration on the electronic properties
+of HfO2 and Ta/HfO2 systems, and thereby create the entire story on RRAMTM's
+switching mechanism. Computational results on the activation energy barrier for
+oxygen vacancy migration were found to be consistent with the results of set
+and reset pulse voltage obtained from experiment. Understanding of this
+mechanism would be beneficial to effectively realize materials design in these
+devices.",1112.2500v1
+2011-12-15,Intrinsic origin of the two-dimensional electron gas at polar oxide interfaces,"The predictions of the polar catastrophe scenario to explain the occurrence
+of a metallic interface in heterostructures of the solid
+solution(LaAlO$_3$)$_{x}$(SrTiO$_3$)$_{1-x}$ (LASTO:x) grown on (001) SrTiO$_3$
+were investigated as a function of film thickness and $x$. The films are
+insulating for the thinnest layers, but above a critical thickness, $t_c$, the
+interface exhibits a constant finite conductivity which depends in a
+predictable manner on $x$. It is shown that $t_c$ scales with the strength of
+the built-in electric field of the polar material, and is immediately
+understandable in terms of an electronic reconstruction at the nonpolar-polar
+interface. These results thus conclusively identify the polar-catastrophe model
+as the intrinsic origin of the doping at this polar oxide interface.",1112.3532v1
+2011-12-20,Computational studies for reduced graphene oxide in hydrogen-rich environment,"We employ molecular dynamic simulations to study the reduction process of
+graphene-oxide (GO) in a chemically active environment enriched with hydrogen.
+We examine the concentration and pressure of hydrogen gas as a function of
+temperature in which abstraction of oxygen is possible with minimum damage to
+C-sp$^2$ bonds hence preserving the integrity of the graphene sheet. Through
+these studies we find chemical pathways that demonstrate beneficiary mechanisms
+for the quality of graphene including formation of water as well as suppression
+of carbonyl pair holes in favor of hydroxyl and epoxy formation facilitated by
+hydrogen gas in the environment.",1112.4546v1
+2011-12-20,"Comment on ""Uncovering the Complex Behavior of Hydrogen in Cu2O""","In a recent Letter Scanlon and Watson reported their first principles results
+on hydrogen in Cu2O. Their main conclusions are: (1) an interstitial H in Cu2O
+prefers to occupy the tetrahedral site, which is coordinated with four Cu
+cations, in all three charge states (+1, neutral, and -1); (2) H will bind with
+a Cu vacancy and form an electrically active H-VCu defect complex, which is
+amphoteric with (+/0) and (0/-)transition levels at Ev + 0.1 and Ev + 1.1 eV,
+respectively. However, these two conclusions contradict two generally observed
+behaviors of H in oxides: (i) cationic H usually binds with an O atom, forming
+a single O-H bond, while the anionic H usually binds with cations with
+multi-coordination; (ii) H usually passivates cation vacancies in oxides. In
+this Comment, we explicitly show that with charge state +1, H prefers to bind
+with a single O anion rather than with four Cu cations and that H-VCu does not
+induce any defect levels inside the band gap.",1112.4840v1
+2011-12-23,Ionically-mediated electromechanical hysteresis in transition metal oxides,"Electromechanical activity, remanent polarization states, and hysteresis
+loops in paraelectric TiO2 and SrTiO3 are observed. The coupling between the
+ionic dynamics and incipient ferroelectricity in these materials is analyzed
+using extended Ginsburg Landau Devonshire (GLD) theory. The possible origins of
+electromechanical coupling including ionic dynamics, surface-charge induced
+electrostriction, and ionically-induced ferroelectricity are identified. For
+the latter, the ionic contribution can change the sign of first order GLD
+expansion coefficient, rendering material effectively ferroelectric. These
+studies provide possible explanation for ferroelectric-like behavior in
+centrosymmetric transition metal oxides.",1112.5581v2
+2012-02-08,Electron dephasing in homogeneous and inhomogeneous indium tin oxide thin films,"The electron dephasing processes in two-dimensional homogeneous and
+inhomogeneous indium tin oxide thin films have been investigated in a wide
+temperature range 0.3--90 K. We found that the small-energy-transfer
+electron-electron ($e$-$e$) scattering process dominated the dephasing from a
+few K to several tens K. At higher temperatures, a crossover to the
+large-energy-transfer $e$-$e$ scattering process was observed. Below about 1--2
+K, the dephasing time $\tau_\varphi$ revealed a very weak temperature
+dependence, which intriguingly scaled approximately with the inverse of the
+electron diffusion constant $D$, i.e., $\tau_\varphi (T \approx 0.3 \, {\rm K})
+\propto 1/D$. Theoretical implications of our results are discussed. The reason
+why the electron-phonon relaxation rate is negligibly weak in this
+low-carrier-concentration material is presented.",1202.1627v1
+2012-03-20,Optical and Luminescence Properties of Zinc Oxide,"We generalize and systematize basic experimental data on optical and
+luminescence properties of ZnO single crystals, thin films, powders, ceramics,
+and nanocrystals. We consider and study mechanisms by which two main emission
+bands occur, a short-wavelength band near the fundamental absorption edge and a
+broad long-wavelength band, the maximum of which usually lies in the green
+spectral range. We determine a relationship between the two luminescence bands
+and study in detail the possibility of controlling the characteristics of ZnO
+by varying the maximum position of the short-wavelength band. We show that the
+optical and luminescence characteristics of ZnO largely depend on the choice of
+the corresponding impurity and the parameters of the synthesis and subsequent
+treatment of the sample. Prospects for using zinc oxide as a scintillator
+material are discussed. Additionally, we consider experimental results that are
+of principal interest for practice.",1203.4366v1
+2012-03-21,Reversible Superconductivity in Electrochromic Indium-Tin Oxide Films,"Transparent conductive indium tin oxide (ITO) thin films, electrochemically
+intercalated with sodium or other cations, show tunable superconducting
+transitions with a maximum $T_c$ at 5 K. The transition temperature and the
+density of states, $D(E_F)$ (extracted from the measured Pauli susceptibility
+$\chi_p$ exhibit the same dome shaped behavior as a function of electron
+density. Optimally intercalated samples have an upper critical field $\approx
+4$ T and $\Delta/{k_BT_c} \approx 2.0$. Accompanying the development of
+superconductivity, the films show a reversible electrochromic change from
+transparent to colored and are partially transparent (orange) at the peak of
+the superconducting dome. This reversible intercalation of alkali and alkali
+earth ions into thin ITO films opens diverse opportunities for tunable,
+optically transparent superconductors.",1203.4644v2
+2012-03-21,Few Electron Limit of n-type Metal Oxide Semiconductor Single Electron Transistors,"We report electronic transport on n-type silicon Single Electron Transistors
+(SETs) fabricated in Complementary Metal Oxide Semiconductor (CMOS) technology.
+The n-MOSSETs are built within a pre-industrial Fully Depleted Silicon On
+Insulator (FDSOI) technology with a silicon thickness down to 10 nm on 200 mm
+wafers. The nominal channel size of 20 $\times$ 20 nm$^{2}$ is obtained by
+employing electron beam lithography for active and gate levels patterning. The
+Coulomb blockade stability diagram is precisely resolved at 4.2 K and it
+exhibits large addition energies of tens of meV. The confinement of the
+electrons in the quantum dot has been modeled by using a Current Spin Density
+Functional Theory (CS-DFT) method. CMOS technology enables massive production
+of SETs for ultimate nanoelectronics and quantum variables based devices.",1203.4811v1
+2012-03-30,Using of the natural radioactive elements for determining Ge-detector efficiencies,"A method is proposed to use of the mixture of Uran oxide and non-active
+matrix (e.g., NaCl) and also potassium and lanthanum for determining
+Ge-detector efficiencies. The preparations containing of known amouts of the U
+or K, or La were measured by means of the Ge-detector, which a efficiency curve
+has been obtained through the reference solutions of 241Am, 109Cd, 57Co, 139Ce,
+137Cs, 60Co. Results the measurements were compared the activities of the
+preparations calculated from mass of 235U, 238U, 138La, 40K in the samples, its
+natural abundance, half lives and intensities of gamma lines. Discrepancy of
+the activities in the energy range between 163 and 1461 keV does not exeed 7 %.
+For correct comparison of the activities the coefficients {\omega} were
+calculated, which took into consideration a varied sorption of gamma-rays in
+water and in mixture of the Uran oxide and matrix.",1203.6772v1
+2012-06-05,A pairing hypothesis based on resonating valence bond state for hole doped copper oxide high temperature superconductors,"To explain the high-temperature superconductivity of hole-doped copper-oxide
+high-temperature superconductors (HDCO-HTSCs), Anderson proposed a theory: (A)
+the pseudogap state is a resonating valence-bond (RVB) state below T* and (B)
+the RVB state translates itself into high-temperature superconducting state
+below Tc. In this paper we abandon Anderson theory B but still retain Anderson
+theory A and add three new hypotheses. Jointed three hypotheses with Anderson
+theory A, we construct an effective Hamiltonian of HDCO-HTSCs and explain why
+Tc-line is a dome in phase diagram and why HDCO-HTSCs have a higher Tc than
+that of conventional superconductors.",1206.0862v4
+2012-06-13,High pressures make Hg a transition metal in a thermodynamically stable solid,"The appropriateness of including Hg among the transition metals has been
+debated for a long time. Although the synthesis of HgF$_{4}$ molecules in gas
+phase was reported before, the molecules show strong instabilities and
+dissociate. Therefore, the transition metal propensity of Hg remains an open
+question. Here, we propose that high pressure provides a controllable method
+for preparing unusual oxidation states of matter. Using an advanced structure
+search method based on first-principles electronic structure calculations, we
+predict that under high pressures, Hg can transfer the electrons in its outmost
+$d$ shell to F atoms, thereby acting as a transition metal. Oxidation of Hg to
+the +4 state yielded thermodynamically stable molecular crystals consisting of
+HgF$_{4}$ planar molecules, a typical geometry for $d^{8}$ metal centers.",1206.2874v1
+2012-07-22,Strain-induced stabilization of Al functionalization in graphene oxide nanosheet for enhanced NH3 storage,"Strain effects on the stabilization of Al ad-atom on graphene
+oxide(GO)nanosheet as well as its implications for NH3 storage have been
+investigated using first-principles calculations.The binding energy of Al
+ad-atom on GO is found to be a false indicator of its stability.Tensile strain
+is found to be very effective in stabilizing the Al ad-atom on GO.It
+strengthens the C-O bonds through an enhanced charge transfer from C to O
+atoms. Interestingly,C-O bond strength is found to be the correct index for
+Al's stability.Optimally strained Al-functionalized GO binds up to 6 NH3
+molecules,while it binds no NH3 molecule in unstrained condition.",1207.5243v2
+2012-08-06,A Variant of the Point Defect Model for Passivity of Metals,"A variant of the point defect model originally enunciated by Macdonald and
+co-workers is advanced and its theoretical implications for the steady state
+current density, barrier layer thickness and the concentration of metal vacancy
+at the metal/film interface are deduced. The differences between the original
+point defect model and the present variant are also highlighted. The empirical
+parameters alpha and beta in the original point defect model are replaced with
+two physical parameters Rcont and Rhof which represent respectively the
+electronic contact resistance at the metal/film interface and the electronic
+resistivity of the oxide film. The present variant correctly describes the
+annihilation of the metal vacancies at the metal/film interface and also
+enforces the conservation of particle and defect volumes during the solid-state
+reactions leading to the natural inclusion of the famous Pilling-Bedsworth
+ratio RPB into the model. Diagnostics which help to check the model predictions
+with experiments are given. Use of this variant to describe stress-induced
+failure of the barrier oxide leading to pitting is also discussed.",1208.1096v1
+2012-08-09,The role of charge traps in inducing hysteresis: capacitance - voltage measurements on top gated bilayer graphene,"Understanding the origin of hysteresis in the channel resistance from top
+gated graphene transistors is important for transistor applications.
+Capacitance - voltage measurements across the gate oxide on top gated bilayer
+graphene show hysteresis with a charging and discharging time constant of ~100
+{\mu}s. However, the measured capacitance across the graphene channel does not
+show any hysteresis, but shows an abrupt jump at a high channel voltage due to
+the emergence of an order, indicating that the origin of hysteresis between
+gate and source is due to charge traps present in the gate oxide and graphene
+interface.",1208.1831v1
+2012-08-17,Nanostructured Zinc Oxide as a Prospective Room Temperature Thermoelectric Material,"Nanostructured Zinc oxide (ZnO) was synthesized via a ball milling for 10
+hours using high energy planetary ball mill. Phase purity and homogeneity of
+all the samples have been investigated by X-ray diffraction (XRD) and Field
+Emission Scanning Electron Microscopy (FE-SEM). All the diffraction peaks can
+be indexed to the hexagonal phase ZnO with hexagonal symmetry (space group
+P63mc). Average crystallite size was observed to be 20 nm. There was a
+remarkable suppression in thermal conductivity ({\kappa}) compared to the bulk
+values by a factor of ~50 at room temperature. This suggests to the possibility
+of using nanostructured ZnO as a prospective room temperature thermoelectric
+material.",1208.3519v1
+2012-08-18,The environmental dependence of redox energetics of PuO2 and α-Pu2O3: A quantitative solution from DFT+U calculations,"We report a comprehensive density functional theory (DFT) + $U$ study of the
+energetics of charged and neutral oxygen defects in both PuO$_{2}$ and
+$\alpha$-Pu$_{2}$O$_{3}$, and present a quantitative determination of the
+equilibrium compositions of reduced PuO$_{2}$ (PuO$_{2-x}$) as functions of
+environmental temperature and partial pressure of oxygen, which shows fairly
+agreement with corresponding high-temperature experiments. Under ambient
+conditions, the endothermic reduction of PuO$_{2}$ to $\alpha$-Pu$_{2}$O$_{3} $
+is found to be facilitated by accompanying volume expansion of PuO$_{2-x}$ and
+the possible migration of O-vacancy, whereas further reduction of $\alpha
+$-Pu$_{2}$O$_{3}$ is predicted to be much more difficult. In contrast to the
+endothermic oxidation of PuO$_{2}$,\ the oxidation of $\alpha$-Pu$_{2} $O$_{3}$
+is a stable exothermic process.",1208.3745v1
+2012-08-22,Optical modes in oxide-apertured micropillar cavities,"We present a detailed experimental characterization of the spectral and
+spatial structure of the confined optical modes for oxide-apertured micropillar
+cavities, showing good-quality Hermite-Gaussian profiles, easily mode-matched
+to external fields. We further derive a relation between the frequency
+splitting of the transverse modes and the expected Purcell factor. Finally, we
+describe a technique to retrieve the profile of the confining refractive index
+distribution from the spatial profiles of the modes.",1208.4472v2
+2012-09-06,High-temperature thermoelectric properties of the double-perovskite ruthenium oxide (Sr$_{1-x}$La$_x$)$_2$ErRuO$_6$,"We have prepared polycrystalline samples of (Sr$_{1-x}$La$_x$)$_2$ErRuO$_6$
+and (Sr$_{1-x}$La$_x$)$_2$YRuO$_6$, and have measured the resistivity, Seebeck
+coefficient, thermal conductivity, susceptibility and x-ray absorption in order
+to evaluate the electronic states and thermoelectric properties of the doped
+double-perovskite ruthenates. We have observed a large Seebeck coefficient of
+-160 $\mu$V/K and a low thermal conductivity of 7 mW/cmK for $x$=0.1 at 800 K
+in air. These two values are suitable for efficient oxide thermoelectrics,
+although the resistivity is still as high as 1 $\Omega$cm. From the
+susceptibility and x-ray absorption measurements, we find that the doped
+electrons exist as Ru$^{4+}$ in the low spin state. On the basis of the
+measured results, the electronic states and the conduction mechanism are
+discussed.",1209.1250v1
+2012-09-13,Origin of the Superior Conductivity of Perovskite Ba(Sr)SnO3,"ASnO3 (A=Ba, Sr) are unique perovskite oxides in that they have superior
+electron conductivity despite their wide optical band gaps. Using
+first-principles band structure calculations, we show that the small electron
+effective masses, thus, good electron conductivity of ASnO3 can be attributed
+to the large size of Sn in this system that gives the conduction band edge with
+antibonding Sn and O s characters. Moreover, we show that ASnO3 can be easily
+doped by La with shallow LaA(+/0) donor level. Our results, therefore,
+explained why the perovskite BaSnO3, SrSnO3, and their alloys are promising
+candidates for transparent conducting oxides.",1209.2845v3
+2012-09-14,Trapped charge dynamics in InAs nanowires,"We study random telegraph noise in the conductance of InAs nanowire
+field-effect transistors due to single electron trapping in defects. The
+electron capture and emission times are measured as functions of temperature
+and gate voltage for individual traps, and are consistent with traps residing
+in the few-nanometer-thick native oxide, with a Coulomb barrier to trapping.
+These results suggest that oxide removal from the nanowire surface, with proper
+passivation to prevent regrowth, should lead to the reduction or elimination of
+random telegraph noise, an important obstacle for sensitive experiments at the
+single electron level.",1209.3237v2
+2012-10-04,"Oxygen reduction activity on perovskite oxide surfaces: a comparative first-principle study of LaMnO$_3$, LaFeO$_3$ and LaCrO$_3$","The understanding of oxygen reduction reaction (ORR) activity on perovskite
+oxide surfaces is essential for promising future fuel cell applications. We
+report a comparative study of ORR mechanisms on La$B$O$_3$ ($B$=Mn, Fe, Cr)
+surfaces by first-principles calculations based on density functional theory
+(DFT). Results obtained from varied DFT methods such as generalized gradient
+approximation(GGA), GGA+$U$ and the hybrid Hartree-Fock density functional
+method are reported for comparative purposes. We find that the results
+calculated from hybrid-functional method suggest that the order of ORR activity
+is LaMnO$_3$ $>$ LaCrO$_3$ $>$ LaFeO$_3$, which is in better agreement with
+recent experimental results (Suntivich \textit{et al.}, Nature Chemistry 3, 546
+(2011)) than those using the GGA or GGA+$U$ method.",1210.1554v1
+2012-10-05,Preparation of atomically-flat SrTiO3 surfaces using a deionized-water etching and thermal annealing procedure,"We report that a deionized water etching and thermal annealing technique can
+be effective for preparing atomically-flat and singly-terminated surfaces of
+single crystalline SrTiO3 substrates. After a two-step thermal-annealing and
+deionized-water etching procedure, topography measured by atomic force
+microscopy shows the evolution of substrates from a rough to step-terraced
+surface structure. Lateral force microscopy confirms that the atomically-flat
+surfaces are singly-terminated. Moreover, this technique can be used to remove
+excessive strontium oxide or hydroxide composites segregated on the SrTiO3
+surface. This acid-etchant-free technique facilitates the preparation of
+atomically-aligned SrTiO3 substrates, which promotes studies on two-dimensional
+physics of complex oxide interfaces.",1210.1860v1
+2012-10-05,Efros-Shklovskii variable range hopping in reduced graphene oxide sheets of varying carbon sp2 fraction,"We investigate the low temperature electron transport properties of
+chemically reduced graphene oxide (RGO) sheets with different carbon sp2
+fractions of 55 to 80 %. We show that in the low bias (Ohmic) regime, the
+temperature (T) dependent resistance (R) of all the devices follow
+Efros-Shklovskii variable range hopping (ES-VRH) R ~ exp[(T(ES)/T)^1/2] with
+T(ES) decreasing from 30976 to 4225 K and electron localization length
+increasing from 0.46 to 3.21 nm with increasing sp2 fraction. From our data, we
+predict that for the temperature range used in our study, Mott-VRH may not be
+observed even at 100 % sp2 fraction samples due to residual topological defects
+and structural disorders. From the localization length, we calculate a bandgap
+variation of our RGO from 1.43 to 0.21 eV with increasing sp2 fraction from 55
+to 80 % which agrees remarkably well with theoretical prediction. We also show
+that, in the high bias regime, the hopping is field driven and the data follow
+R ~ exp[(E(0)/E)^1/2] providing further evidence of ES-VRH.",1210.1876v1
+2012-10-08,Doped Mott Insulators in (111) Bilayers of Perovskite Transition-Metal Oxides with a Strong Spin-Orbit Coupling,"The electronic properties of Mott insulators realized in (111) bilayers of
+perovskite transition-metal oxides are studied. The low-energy effective
+Hamiltonians for such Mott insulators are derived in the presence of a strong
+spin-orbit coupling. These models are characterized by the antiferromagnetic
+Heisenberg interaction and the anisotropic interaction whose form depends on
+the $d$ orbital occupancy. From exact diagonalization analyses on finite
+clusters, the ground state phase diagrams are derived, including a Kitaev spin
+liquid phase in a narrow parameter regime for $t_{2g}$ systems. Slave-boson
+mean-field analyses indicate the possibility of novel superconducting states
+induced by carrier doping into the Mott-insulating parent systems, suggesting
+the present model systems as unique playgrounds for studying
+correlation-induced novel phenomena. Possible experimental realizations are
+also discussed.",1210.2290v3
+2012-10-13,Promising ferrimagnetic double perovskite oxides towards high spin polarization at high temperature,"We predict through our first-principles calculations that four double
+perovskite oxides of Bi2ABO6 (AB = FeMo, MnMo, MnOs, CrOs) are half-metallic
+ferrimagnets. Our calculated results shows that the four optimized structures
+have negative formation energy, from -0.42 to -0.26 eV per formula unit, which
+implies that they could probably be realized. In the case of Bi2FeMoO6, the
+half-metallic gap and Curie temperature are predicted to reach to 0.71 eV and
+650 K, respectively, which indicates that high spin polarization could be kept
+at high temperatures far beyond room temperature. It is believed that some of
+them could be synthesized soon and would prove useful for spintronic
+applications.",1210.3706v2
+2012-10-24,Combined GW and dynamical mean field theory: Dynamical screening effects in transition metal oxides,"We present the first dynamical implementation of the combined GW and
+dynamical mean field scheme (""GW+DMFT"") for first principles calculations of
+the electronic properties of correlated materials. The application to the
+ternary transition metal oxide SrVO3 demonstrates that this schemes inherits
+the virtues of its two parent theories: a good description of the local low
+energy correlation physics encoded in a renormalized quasi-particle band
+structure, spectral weight transfer to Hubbard bands, and the physics of
+screening driven by long-range Coulomb interactions. Our data is in good
+agreement with available photoemission and inverse photoemission spectra; our
+analysis leads to a reinterpretation of the commonly accepted ""three-peak
+structure"" as originating from orbital effects rather than from the electron
+addition peak within the t2g manifold.",1210.6580v2
+2012-10-30,High mobility conduction at (110) and (111) LaAlO3/SrTiO3 interfaces,"In recent years, striking discoveries have revealed that two-dimensional
+electron liquids (2DEL) confined at the interface between oxide band-insulators
+can be engineered to display a high mobility transport. The recognition that
+only few interfaces appear to suit hosting 2DEL is intriguing and challenges
+the understanding of these emerging properties not existing in bulk. Indeed,
+only the neutral TiO2 surface of (001)SrTiO3 has been shown to sustain 2DEL. We
+show that this restriction can be surpassed: (110) and (111) surfaces of SrTiO3
+interfaced with epitaxial LaAlO3 layers, above a critical thickness, display
+2DEL transport with mobilities similar to those of (001)SrTiO3. Moreover we
+show that epitaxial interfaces are not a prerequisite: conducting (110)
+interfaces with amorphous LaAlO3 and other oxides can also be prepared. These
+findings open a new perspective both for materials research and for elucidating
+the ultimate microscopic mechanism of carrier doping.",1210.7955v1
+2012-11-16,Single-layer MoS2 as efficient photocatalyst,"The potential application of the single-layer MoS2 as photocatalyst was
+revealed in this work based on first-principles calculations. It is found that
+the pristine single-layer MoS2 is a good candidate for photocatalyst, and its
+catalyzing ability can be tuned by the applied mechanical strain. Furthermore,
+the p-type doping could improve the catalyzing ability more efficiently: first,
+the p-type doping makes the direct transition of electron from valence band
+maximum (VBM) to conduction band minimum (CBM) viable; second, it separates the
+water splitting reaction sites by having reduction in Mo sites and oxidation in
+P dopant sites; third, it improves the efficiency by equalizing the reducing
+power {\Delta}1 and oxidizing power {\Delta}2, as well as by enhancing the
+light absorption in long wavelength end of the visible light. Thus enables the
+single-layer MoS2 to be a efficient visible-light photocatalyst.",1211.4052v2
+2012-11-24,Ab initio simulations of oxygen interaction with surfaces and interfaces in uranium mononitride,"The results of DFT supercell calculations of oxygen behavior upon the UN
+(001) and (110) surfaces as well as at the tilt grain boundary are presented.
+Oxygen adsorption, migration, incorporation into the surface N vacancies on
+(001) and (110) surfaces have been modeled using 2D slabs of different
+thicknesses and supercell sizes. The temperature dependences of the N vacancy
+formation energies and oxygen incorporation energies are calculated. We
+demonstrate that O atoms easily penetrate into UN surfaces and grain boundaries
+containing N vacancies, due to negative incorporation energies and a small
+energy barrier. The Gibbs free energies of N vacancy formation and O atom
+incorporation therein at the two densely-packed surfaces and tilt grain
+boundaries are compared. It has been also shown that the adsorbed oxygen atoms
+are highly mobile which, combined with easy incorporation into surface N
+vacancies, explains efficient (but unwanted) oxidation of UN surfaces. The
+atomistic mechanism of UN oxidation via possible formation of oxynitrides is
+discussed.",1211.5695v1
+2012-11-26,Complex Orbital State Stabilized by Strong Spin-Orbit Coupling in a Metallic Iridium Oxide IrO$_{2}$,"Resonant x-ray diffraction experiments were performed for the metallic
+iridium oxide IrO$_{2}$. We observed anisotropic tensor of susceptibility (ATS)
+scattering, the spectrum of which shows a sharp contrast between the $L_{3}$
+and $L_{2}$ edges. At the $L_{3}$ edge, resonance excitations were clearly
+observed from the core 2$p$ orbitals to both the 5$d$ $t_{2g}$ and $e_{g}$
+orbitals. In contrast, the resonance mode associated with 5$d$ $t_{2g}$
+orbitals was indiscernible at the $L_{2}$ edge. This contrasting behavior
+indicates that Ir 5$d$ $t_{2g}$ orbitals are fairly close to the $J_{\rm eff}$
+= 1/2 state due to the strong spin--orbit coupling in 5$d$ transition metal
+ions, as in the Mott insulator Sr$_{2}$IrO$_{4}$. Our results clearly
+demonstrate that ATS scattering is a useful probe for investigating complex
+orbital states in a metallic state. Such states induce novel phenomena such as
+the spin Hall effect.",1211.5855v1
+2012-11-29,Surface composition of BaTiO3/SrTiO3(001) films grown by atomic oxygen plasma assisted molecular beam epitaxy,"We have investigated the growth of BaTiO3 thin films deposited on pure and 1%
+Nb-doped SrTiO3(001) single crystals using atomic oxygen assisted molecular
+beam epitaxy (AO-MBE) and dedicated Ba and Ti Knudsen cells. Thicknesses up to
+30 nm were investigated for various layer compositions. We demonstrate 2D
+growth and epitaxial single crystalline BaTiO3 layers up to 10 nm before
+additional 3D features appear; lattice parameter relaxation occurs during the
+first few nanometers and is completed at {\guillemotright}10 nm. The presence
+of a Ba oxide rich top layer that probably favors 2D growth is evidenced for
+well crystallized layers. We show that the Ba oxide rich top layer can be
+removed by chemical etching. The present work stresses the importance of
+stoichiometry and surface composition of BaTiO3 layers, especially in view of
+their integration in devices.",1211.6994v1
+2012-12-04,Epitaxial growth of (111)-oriented LaAlO$_3$/LaNiO$_3$ ultra-thin superlattices,"The epitaxial stabilization of a single layer or superlattice structures
+composed of complex oxide materials on polar (111) surfaces is severely
+burdened by reconstructions at the interface, that commonly arise to neutralize
+the polarity. We report on the synthesis of high quality LaNiO$_3$/mLaAlO$_3$
+pseudo cubic (111) superlattices on polar (111)-oriented LaAlO$_3$, the
+proposed complex oxide candidate for a topological insulating behavior.
+Comprehensive X-Ray diffraction measurements, RHEED, and element specific
+resonant X-ray absorption spectroscopy affirm their high structural and
+chemical quality. The study offers an opportunity to fabricate interesting
+interface and topology controlled (111) oriented superlattices based on
+ortho-nickelates.",1212.0590v1
+2012-12-07,Monte Carlo study of an unconventional superconducting phase in Ir-oxide J_{eff}=1/2 Mott insulators induced by carrier doping,"Based on a microscopic theoretical study, we show that novel
+superconductivity is induced by carrier doping in layered perovskite Ir oxides
+where a strong spin-orbit coupling causes an effective total angular momentum
+J_{eff}=1/2 Mott insulator. Using a variational Monte Carlo method, we find an
+unconventional superconducting state in the ground state phase diagram of a
+t_{2g} three-orbital Hubbard model on the square lattice. This superconducting
+state is characterized by a d_{x^2-y^2}-wave ""pseudospin singlet"" formed by the
+J_{eff}=1/2 Kramers doublet, which thus contains inter-orbital as well as both
+singlet and triplet components of t_{2g} electrons. The superconducting state
+is found stable only by electron doping, but not by hole doping, for the case
+of carrier doped Sr_2IrO_4. We also study an effective single-orbital Hubbard
+model to discuss the similarities to high-T_c cuprate superconductors and the
+multi-orbital effects.",1212.1546v1
+2012-12-11,Characterization of nanostructured material images using fractal descriptors,"This work presents a methodology to the morphology analysis and
+characterization of nanostructured material images acquired from FEG-SEM (Field
+Emission Gun-Scanning Electron Microscopy) technique. The metrics were
+extracted from the image texture (mathematical surface) by the volumetric
+fractal descriptors, a methodology based on the Bouligand-Minkowski fractal
+dimension, which considers the properties of the Minkowski dilation of the
+surface points. An experiment with galvanostatic anodic titanium oxide samples
+prepared in oxalyc acid solution using different conditions of applied current,
+oxalyc acid concentration and solution temperature was performed. The results
+demonstrate that the approach is capable of characterizing complex morphology
+characteristics such as those present in the anodic titanium oxide.",1212.2677v1
+2012-12-20,Electrostatic Tuning of the Properties of Disordered Indium Oxide Films near the Superconductor-Insulator Transition,"The evolution with carrier concentration of the electrical properties of
+amorphous indium oxide (InO) thin films has been studied using electronic
+double layer transistor configurations. Carrier variations of up to 7 X 10^(14)
+carriers/cm^2 were achieved using an ionic liquid as a gate dielectric. The
+superconductor-insulator transition was traversed and the magnitude and
+position of the large magnetoresistance peak found in the insulating regime
+were modified. The systematic variation of the magnetoresistance peak with
+charge concentration was found to be qualitatively consistent with a simulation
+based on a model involving granularity.",1212.5177v2
+2012-12-26,Oxidation of self-duality to 12 dimensions and beyond,"Using (partial) curvature flows and the transitive action of subgroups of
+O(d,Z) on the indices {1,...,d} of the components of the Yang-Mills curvature
+in an orthonormal basis, we obtain a nested system of equations in successively
+higher dimensions d, each implying the Yang-Mills equations on d-dimensional
+Riemannian manifolds possessing special geometric structures. This `matryoshka'
+of self-duality equations contains the familiar self-duality equations on
+Riemannian 4-folds as well as their generalisations on complex K\""ahler 3-folds
+and on 7- and 8-dimensional manifolds with G_2 and Spin(7) holonomy. The
+matryoshka allows enlargement (`oxidation') to a remarkable system in 12
+dimensions invariant under Sp(3). There are hints that the underlying geometry
+is related to the sextonions, a six-dimensional algebra between the quaternions
+and octonions.",1212.6270v3
+2012-12-31,Metallic and insulating interfaces of amorphous SrTiO3-based oxide heterostructures,"The conductance confined at the interface of complex oxide heterostructures
+provides new opportunities to explore nanoelectronic as well as nanoionic
+devices. Herein we show that metallic interfaces can be realized in
+SrTiO3-based heterostructures with various insulating overlayers of amorphous
+LaAlO3, SrTiO3 and yttria-stabilized zirconia films. On the other hand, samples
+of amorphous La7/8Sr1/8MnO3 films on SrTiO3 substrates remain insulating. The
+interfacial conductivity results from the formation of oxygen vacancies near
+the interface, suggesting that the redox reactions on the surface of SrTiO3
+substrates play an important role.",1212.6901v1
+2013-01-05,Potential thermoelectric performance of hole-doped Cu2O,"High thermoelectric performance in oxides requires stable conductive
+materials that have suitable band structures. Here we show based on an analysis
+of the thermopower and related properties using first-principles calculations
+and Boltzmann transport theory that hole doped Cu2O may be such a material. We
+find that hole-doped Cu2O has a high thermopower of above 200 microV/K even
+with doping levels as high as 5.5x10 20 cm-3 at 500 K, mainly attributed to the
+heavy valence bands of Cu2O. This is reminiscent of the cobaltate family of
+high performance oxide thermoelectrics and implies that hole-doped Cu2O could
+be an excellent thermoelectric material if suitably doped.",1301.0913v1
+2013-01-07,Oxidizing Borcherds symmetries,"The tensor hierarchy of maximal supergravity in D dimensions is known to be
+closely related to a Borcherds (super)algebra that is constructed from the
+global symmetry group E(11-D). We here explain how the Borcherds algebras in
+different dimensions are embedded into each other and can be constructed from a
+unifying Borcherds algebra. The construction also has a natural physical
+explanation in terms of oxidation. We then go on to show that the Hodge duality
+that is present in the tensor hierarchy has an algebraic counterpart. For D>8
+the Borcherds algebras we find differ from the ones existing in the literature
+although they generate the same tensor hierarchy.",1301.1346v1
+2013-01-14,ω/T scaling of the optical conductivity in strongly correlated layered cobalt oxide,"We report infrared spectroscopic properties of the strongly correlated
+layered cobalt oxide [BiBa$_{0.66}$K$_{0.36}$O$_2$]CoO$_2$. These measurements
+performed on single crystals allow us to determine the optical conductivity as
+a function of temperature. In addition to a large temperature dependent
+transfer of spectral weight, an unconventional low energy mode is found. We
+show that both its frequency and damping scale as the temperature itself. In
+fact, a basic analysis demonstrates that this mode fully scales onto a function
+of $\omega$/T up to room temperature. This behavior suggests low energy
+excitations of non-Fermi liquid type originating from quantum criticality.",1301.2970v1
+2013-01-17,Dimer Mott Insulator in an Oxide Heterostructure,"We study the problem of designing an artificial Mott insulator in a
+correlated oxide heterostructure. We consider the extreme limit of quantum
+confinement based on ionic discontinuity doping, and argue that a unique dimer
+Mott insulator can be achieved for the case of a single SrO layer in a
+GdTiO$_3$ matrix. In the dimer Mott insulator, electrons are localized not to
+individual atoms but to bonding orbitals on molecular dimers formed across a
+bilayer of two TiO$_2$ planes, and is analogous to the Mott insulating state of
+Hubbard ladders, studied in the 1990s. We verify the existence of the dimer
+Mott insulator through both ab initio and model Hamiltonian studies, and find
+for reasonable values of Hubbard $U$ that it is stable and ferromagnetic with a
+clear bonding/anti-bonding splitting of order 0.65eV, and a significant smaller
+Mott gap whose size depends upon $U$. The combined effects of polar
+discontinuity, strong structural relaxation and electron correlations all
+contribute to the realization of this unique ground state.",1301.4222v1
+2013-01-18,Pure rotational spectra of TiO and TiO_2 in VY Canis Majoris,"We report the first detection of pure rotational transitions of TiO and TiO_2
+at (sub-)millimeter wavelengths towards the red supergiant VY CMa. A rotational
+temperature, T_rot, of about 250 K was derived for TiO_2. Although T_rot was
+not well constrained for TiO, it is likely somewhat higher than that of TiO_2.
+The detection of the Ti oxides confirms that they are formed in the
+circumstellar envelopes of cool oxygen-rich stars and may be the ""seeds"" of
+inorganic-dust formation, but alternative explanations for our observation of
+TiO and TiO_2 in the cooler regions of the envelope cannot be ruled out at this
+time. The observations suggest that a significant fraction of the oxides is not
+converted to dust, but instead remains in the gas phase throughout the outflow.",1301.4344v1
+2013-01-22,Oxidation of D=3 cosets and Bonnor dualities in $D\leq 6$,"Bonnor's map in General Relativity is duality between (dimensionally reduced)
+vacuum gravity and static truncation of electro-vacuum theory. It was used as a
+tool to generate an exact solution of electro-vacuum from some vacuum solution.
+It can be expected that similar dualities will be useful for solution
+generation in higher-dimensional theories too. Here we study such maps within a
+class of theories in dimensions $D\leq 6$ using oxidation of D=3 cosets and
+consistent truncation of the corresponding theories. Our class includes those
+theories whose D=3 symmetries are subgroups of $G=O(5,4)$. It contains
+six-dimensional minimal supergravity, five-dimensional minimal and $U(1)^3$
+supergravities and a number of four-dimensional theories which attracted
+attention recently in the search of exact solutions. We give explicit
+reduction/truncation formulas relating different theories in dimensions $D=4,
+5, 6$ in terms of metrics and matter fields and discuss various alternative
+duality chains between them.",1301.5084v2
+2013-01-28,Tunneling through Al/AlOx/Al junction: analytical models and first principles simulations,"We study from first principles the transport properties of Al/AlOx/Al tunnel
+junctions. On this basis, we analyze the reliability of two analytical models
+for the conductance, namely the trapezoid potential barrier model and a
+tight-binding model. Our findings show that (i) the interface width used in the
+models is determined by the electronic density profile, and it is shorter than
+the width one expects from the atomic arrangements; (ii) the effective mass},
+found to be about on third of the free electron mass, can be determined from
+the oxide band-structure calculations, and (iii) the barrier height is given by
+one fourth of the bandgap in the oxide, which explains the apparently small
+values found for these junctions experimentally.",1301.6536v1
+2013-01-31,Nanoscale Surface Analysis on Second Generation Advanced High Strength Steel after Hot Dip Galvanizing,"Second Generation advanced high strength steel is the material of choice for
+modern automotive structural parts because of its outstanding maximal
+elongation and tensile strength. Nonetheless there is still a lack of corrosion
+protection for this material due to the fact that cost efficient hot dip
+galvanizing can not be applied. The reason for the insufficient coatability
+with zinc is found in the segregation of manganese to the surface during
+annealing and the formation of manganese oxides prior coating. This work
+analyses the structure and chemical composition of the surface oxides on so
+called nano-TWIP (twinning induced plasticity) steel on the nanoscopic scale
+after hot dip galvanizing in a simulator with employed analytical methods
+comprising scanning Auger electron spectroscopy (SAES), energy dispersive x-ray
+spectroscopy (EDX), and focused ion beam (FIB) for cross section preparation.
+By the combination of these methods it was possible to obtain detailed chemical
+images serving a better understanding which processes exactly occur on the
+surface of this novel kind of steel and how to promote in the future for this
+material system galvanic protection.",1301.7733v1
+2013-02-01,Electronic properties and Fermi surface for new Fe-free layered superconductor BaTi2Bi2O from first principles,"Very recently, as an important step in the development of layered Fe-free
+pnictide-oxide superconductors, the new phase BaTi2Bi2O was discovered which
+has the highest TC (about 4.6 K) among all related non-doped systems. In this
+Letter, we report for the first time the electronic bands, Fermi surface
+topology, total and partial densities of electronic states for BaTi2Bi2O
+obtained by means of the first-principles FLAPW-GGA calculations. The
+inter-atomic bonding picture is described as a high-anisotropic mixture of
+metallic, covalent, and ionic contributions. Besides, the structural and
+electronic factors, which can be responsible for the increased transition
+temperature for BaTi2Bi2O (as compared with related pnictide-oxides BaTi2As2O
+and BaTi2Sb2O), are discussed.",1302.0108v1
+2013-02-06,In situ X-ray photoelectron spectroscopy of model catalysts: At the edge of the gap,"We present a High-Pressure X-ray Photoelectron Spectroscopy (HP-XPS) and
+first-principles kinetic Monte Carlo study addressing the nature of the active
+surface in CO oxidation over Pd(100). Simultaneously measuring the chemical
+composition at the surface and in the near-surface gas-phase, we reveal both
+O-covered pristine Pd(100) and a surface oxide as stable, highly active phases
+in the near-ambient regime accessible to HP-XPS. Surprisingly, no adsorbed CO
+can be detected during high CO2 production rates, which can be explained by a
+combination of a remarkably short residence time of the CO molecule on the
+surface and mass-transfer limitations in the present set-up.",1302.1388v1
+2013-02-08,Ultra-high-ohmic microstripline resistors for Coulomb blockade devices,"In this paper, we report on the fabrication and the low-temperature
+characterization of extremely high-ohmic microstrip resistors made of a thin
+film of weakly oxidized titanium. Nearly linear voltage-current characteristics
+were measured at temperatures down to $T \sim \unit[20]{mK}$ for films with
+sheet resistivity up to as high as $\sim \unit[7]{k\Omega}$, i.e. about an
+order of magnitude higher than our previous findings for weakly oxidized Cr.
+Our analysis indicates that such an improvement can help to create an
+advantageous high-impedance environment for different Coulomb blockade devices.
+Further properties of the Ti film addressed in this work show a promise of
+low-noise behavior of the resistors when applied in different realizations of
+the quantum standard of current.",1302.2086v1
+2013-02-08,Metal nanoparticle field-effect transistor,"We demonstrate that by means of a local top-gate current oscillations can be
+observed in extended, monolayered films assembled from monodisperse metal
+nanocrystals -- realizing transistor function. The oscillations in this
+metal-based system are due to the occurrence of a Coulomb energy gap in the
+nanocrystals which is tunable via the nanocrystal size. The nanocrystal
+assembly by the Langmuir-Blodgett method yields homogeneous monolayered films
+over vast areas. The dielectric oxide layer protects the metal nanocrystal
+field-effect transistors from oxidation and leads to stable function for
+months. The transistor function can be reached due to the high monodispersity
+of the nanocrystals and the high super-crystallinity of the assembled films.
+Due to the fact that the film consists of only one monolayer of nanocrystals
+and all nanocrystals are simultaneously in the state of Coulomb blockade the
+energy levels can be influenced efficiently (limited screening).",1302.2110v2
+2013-02-13,Electronic phase diagram of high temperature copper oxide superconductors,"In order to understand the origin of high-temperature superconductivity in
+copper oxides, we must understand the normal state from which it emerges. Here,
+we examine the evolution of the normal state electronic excitations with
+temperature and carrier concentration in Bi2Sr2CaCu2O8 using angle-resolved
+photoemission. In contrast to conventional superconductors, where there is a
+single temperature scale Tc separating the normal from the superconducting
+state, the high- temperature superconductors exhibit two additional temperature
+scales. One is the pseudogap scale T*, below which electronic excitations
+exhibit an energy gap. The second is the coherence scale Tcoh, below which
+sharp spectral features appear due to increased lifetime of the excitations. We
+find that T* and Tcoh are strongly doping dependent and cross each other near
+optimal doping. Thus the highest superconducting Tc emerges from an unusual
+normal state that is characterized by coherent excitations with an energy gap.",1302.3252v1
+2013-02-26,Ultrafast plasmonics using transparent conductive oxide hybrids in the epsilon near-zero regime,"The dielectric response of transparent conductive oxides near the bulk
+plasmon frequency is characterized by a refractive index less than vacuum. In
+analogy with x-ray optics, it is shown that this regime results in total
+external reflection and air-guiding of light. In addition, the strong reduction
+of the wavevector in the ITO below that of free space enables a new surface
+plasmon polariton mode which can be excited without requiring a prism or
+grating coupler. Ultrafast control of the surface plasmon polariton mode is
+achieved with a modulation amplitude reaching 20%.",1302.6604v1
+2013-02-27,Ultrafast photoinduced enhancement of nonlinear optical response in 15-atom gold clusters on indium tin oxide conducting film,"We show that the third order optical nonlinearity of 15-atom gold clusters is
+significantly enhanced when in contact with indium tin oxide (ITO) conducting
+film. Open and close aperture z-scan experiments together with non-degenerate
+pump-probe differential transmission experiments were done using 80 fs laser
+pulses centered at 395 nm and 790 nm on gold clusters encased inside
+cyclodextrin cavities. We show that two photon absorption coefficient is
+enhanced by an order of magnitude as compared to that when the clusters are on
+pristine glass plate. The enhancement for the nonlinear optical refraction
+coefficient is ~3 times. The photo-induced excited state absorption using
+pump-probe experiments at pump wavelength of 395 nm and probe at 790 nm also
+show an enhancement by an order of magnitude. These results attributed to the
+excited state energy transfer in the coupled gold cluster-ITO system are
+different from the enhancement seen so far in charge donor-acceptor complexes
+and nanoparticle-conjugate polymer composites.",1302.7001v1
+2013-04-03,Octahedral Engineering of Orbital Polarizations in Charge Transfer Oxides,"Negative charge transfer $AB$O$_3$ oxides may undergo electronic
+metal--insulator transitions (MIT) concomitant with a dilation and contraction
+of nearly rigid octahedra. On both sides of the MIT are in-phase or
+out-of-phase (or both) rotations of adjacent octahedra that buckle the
+$B$--O--$B$ bond angle away from 180$^\circ$. Using density functional theory
+with the PBEsol$+U$ approach, we describe a novel octahedral engineering avenue
+to control the $B$ 3d and O $2p$ orbital polarization through enhancement of
+the $B$O$_6$ rotation ""sense"" rather than solely through conventional changes
+to the $B$--O bond lengths, \emph{i.e.} crystal field distortions. Using
+CaFeO$_3$ as a prototypical material, we show the flavor of the octahedral
+rotation pattern when combined with strain--rotation coupling and thin film
+engineering strategies offers a promising avenue to fine tune orbital
+polarizations near electronic phase boundaries.",1304.0982v1
+2013-04-10,Multi-band superconductivity and nanoscale inhomogeneity at oxide interfaces,"The two-dimensional electron gas at the LaTiO3/SrTiO3 or LaAlO3/SrTiO3 oxide
+interfaces becomes superconducting when the carrier density is tuned by gating.
+The measured resistance and superfluid density reveal an inhomogeneous
+superconductivity resulting from percolation of filamentary structures of
+superconducting ""puddles"" with randomly distributed critical temperatures,
+embedded in a non-superconducting matrix. Following the evidence that
+superconductivity is related to the appearance of high-mobility carriers, we
+model intra-puddle superconductivity by a multi-band system within a weak
+coupling BCS scheme. The microscopic parameters, extracted by fitting the
+transport data with a percolative model, yield a consistent description of the
+dependence of the average intra-puddle critical temperature and superfluid
+density on the carrier density.",1304.2970v1
+2013-04-16,EUV induced defects on few-layer graphene,"We use Raman spectroscopy to show that exposing few-layer graphene to extreme
+ultraviolet (EUV, 13.5 nm) radiation, i.e. relatively low photon energy,
+results in an increasing density of defects. Furthermore, exposure to EUV
+radiation in a H2 background increases the graphene dosage sensitivity, due to
+reactions caused by the EUV induced hydrogen plasma. X-ray photoelectron
+spectroscopy (XPS) results show that the sp2 bonded carbon fraction decreases
+while the sp3 bonded carbon and oxide fraction increases with exposure dose.
+Our experimental results confirm that even in reducing environment oxidation is
+still one of the main source of inducing defects.",1304.4395v1
+2013-04-22,Electronic Structure Modeling of Electrochemical Reactions at Electrode/Electrolyte Interfaces in Lithium Ion Batteries,"We review recent ab initio molecular dynamics studies of
+electrode/electrolyte interfaces in lithium ion batteries. Our goals are to
+introduce experimentalists to simulation techniques applicable to models which
+are arguably most faithful to experimental conditions so far, and to emphasize
+to theorists that the inherently interdisciplinary nature of this subject
+requires bridging the gap between solid and liquid state perspectives. We
+consider liquid ethylene carbonate (EC) decomposition on lithium intercalated
+graphite, lithium metal, oxide-coated graphite, and spinel manganese oxide
+surfaces. These calculations are put in the context of more widely studied
+water-solid interfaces. Our main themes include kinetically controlled
+two-electron-induced reactions, the breaking of a previously much neglected
+chemical bond in EC, and electron tunneling. Future work on modeling batteries
+at atomic lengthscales requires capabilities beyond state-of-the-art, which
+emphasizes that applied battery research can and should drive fundamental
+science development.",1304.5976v1
+2013-04-26,Learning and Spatiotemporally Correlated Functions Mimicked in Oxide-Based Artificial Synaptic Transistors,"Learning and logic are fundamental brain functions that make the individual
+to adapt to the environment, and such functions are established in human brain
+by modulating ionic fluxes in synapses. Nanoscale ionic/electronic devices with
+inherent synaptic functions are considered to be essential building blocks for
+artificial neural networks. Here, Multi-terminal IZO-based artificial synaptic
+transistors gated by fast proton-conducting phosphosilicate electrolytes are
+fabricated on glass substrates. Proton in the SiO2 electrolyte and IZO channel
+conductance are regarded as the neurotransmitter and synaptic weight,
+respectively. Spike-timing dependent plasticity, short-term memory and
+long-term memory were successfully mimicked in such protonic/electronic hybrid
+artificial synapses. And most importantly, spatiotemporally correlated logic
+functions are also mimicked in a simple artificial neural network without any
+intentional hard-wire connections due to the naturally proton-related coupling
+effect. The oxide-based protonic/electronic hybrid artificial synaptic
+transistors reported here are potential building blocks for artificial neural
+networks.",1304.7072v1
+2013-05-02,Inductively Coupled Plasma etching of amorphous silicon nanostructures over nanotopography using C4F8/SF6 chemistry,"Inductively Coupled Plasma (ICP) etching of amorphous silicon (a-Si)
+nanostructures using a continuous C4F8/SF6 plasma over nanotopography in
+silicon dioxide (SiO2) is investigated. The coil power of the ICP system is
+used to tune the a-Si etch rate from 20 to 125 nm/min. The etch rates of a-Si,
+SiO2 and electroresist are measured depending on the SF6 ratio, platen power
+and chamber pressure and used to optimize the a-Si:SiO2 etch selectivity. The
+results on nanostructures show that the presence of an insulating etch-stop
+layer affects the passivation ratio required to achieve vertical sidewalls. A
+low pressure is also necessary in order to etch the silicon nanostructure
+embedded into the oxide nanotrenches to form a highly conformable a-Si
+nanowire. We argue that both of these behaviors could be explained by surface
+charging effects. Finally, etching of 20 nm a-Si nanowires that cross 15 nm
+trenches in oxide with vertical sidewalls and a 4.3:1 a-Si:SiO2 etch
+selectivity is demonstrated. This etching process can be used in applications
+where nanotopography is present such as single electron transistors or
+multigate transistors.",1305.0589v1
+2013-05-07,Enhanced and continuous electrostatic carrier doping on the SrTiO$_{3}$ surface,"Paraelectrical tuning of a charge carrier density as high as
+10$^{13}$\,cm$^{-2}$ in the presence of a high electronic carrier mobility on
+the delicate surfaces of correlated oxides, is a key to the technological
+breakthrough of a field effect transistor (FET) utilising the metal-nonmetal
+transition. Here we introduce the Parylene-C/Ta$_{2}$O$_{5}$ hybrid gate
+insulator and fabricate FET devices on single-crystalline SrTiO$_{3}$, which
+has been regarded as a bedrock material for oxide electronics. The gate
+insulator accumulates up to $\sim10^{13}$cm$^{-2}$ carriers, while the
+field-effect mobility is kept at 10\,cm$^2$/Vs even at room temperature.
+Further to the exceptional performance of our devices, the enhanced
+compatibility of high carrier density and high mobility revealed the mechanism
+for the long standing puzzle of the distribution of electrostatically doped
+carriers on the surface of SrTiO$_{3}$. Namely, the formation and continuous
+evolution of field domains and current filaments.",1305.1440v1
+2013-05-20,Hidden Structural Order in Orthorhombic Tantalum Pentoxide (Ta$_2$O$_5$),"We investigate using first-principles calculations the atomic structure of
+the orthorhombic phase of Ta$_2$O$_5$. Although this structure has been studied
+for decades, the correct structural model is controversial owing to the
+complication of structural disorder. We identify a new low-energy high-symmetry
+structural model where all Ta and O atoms have correct formal oxidation states
+of +5 and -2, respectively, and the experimentally reported triangular lattice
+symmetry of the Ta sublattice appears dynamically at finite temperatures. To
+understand the complex atomic structure of the Ta$_2$O$_3$ plane, a triangular
+graph-paper representation is devised and used alongside oxidation state
+analysis to reveal infinite variations of the low-energy structural model. The
+structural disorder of Ta$_2$O$_5$ observed in experiments is attributed to the
+intrinsic structural variations, and oxygen vacancies that drive collective
+relaxation of the O sublattice.",1305.4425v1
+2013-05-30,Transport properties of p-type metal-oxide-semiconductor inversion layer in (110) and (111) silicon channel under uniaxial stress,"Valence subband and transport properties of p-type metal-oxide-semiconductor
+(PMOS) inversion layer in uniaxially strained (110) and (111) Si channel have
+been studied theoretically in this work. Equal energy lines, carrier
+concentration effective mass, conductivity effective mass, and mobility are
+calculated based on Luttinger-Kohn Hamiltonian [16]. Three compact expressions
+of scattering rate are derived in this paper. The direction of applied uniaxial
+stresses considered is in either parallel or perpendicular to channel. My
+results show mobility is very sensitive to effective mass under different
+stresses. The favorable mobility directions are found in (110) system with -3
+GPa stress parallel to channel and +3 GPa stress perpendicular to channel.",1305.7037v2
+2013-06-04,GaN / VO2 heteroepitaxial p-n junctions: Band offset and minority carrier dynamics,"We report on experimental realization of p-n heterojunctions based on p-type
+GaN, and an n-type correlated oxide, VO2. The band offsets are evaluated by
+current-voltage and capacitance voltage measurements at various temperatures. A
+band diagram based on the conventional band bending picture is proposed to
+explain the evolution of the apparent barier height from electrical
+measurements and it suggests that the work function of VO2 decreases by ~0.2 eV
+when it goes through the insulator to metal transtion, in qualitative agreement
+with Kelvin force microscopy measurements reported in literature. The frequency
+dependent capacitance measurements allows us to differentiate the miniority
+carrier effect from the interface states and series resistance contributions,
+and estimate the minority carrier lifetime in insulating phase of VO2 to be of
+the order of few microseconds. The nitride-oxide based p-n heterojunctions
+provide a new dimension",1306.0916v1
+2013-06-04,Bipolar electrical switching in metal-metal contacts,"Electrical switching has been observed in carefully designed
+metal-insulator-metal devices built at small geometries. These devices are also
+commonly known as memristors and consist of specific materials such as
+transition metal oxides, chalcogenides, perovskites, oxides with valence
+defects, or a combination of an inert and an electrochemically active
+electrode. No simple physical device has been reported to exhibit electrical
+switching. We have discovered that a simple point-contact or a granular
+arrangement formed of metal pieces exhibits bipolar switching. These devices,
+referred to as coherers, were considered as one-way electrical fuses. We have
+identified the state variable governing the resistance state and can program
+the device to switch between multiple stable resistance states. Our
+observations render previously postulated thermal mechanisms for their
+resistance-change as inadequate. These devices constitute the missing canonical
+physical implementations for memristor, often referred as the fourth passive
+element. Apart from the theoretical advance in understanding metallic contacts,
+the current discovery provides a simple memristor to physicists and engineers
+for widespread experimentation, hitherto impossible.",1306.0942v2
+2013-06-12,Dimensional Oxidation of Non-geometric Fluxes in Type II Orientifolds,"Some aspects of string compactifications with non-geometric fluxes are
+revisited in the light of recent progress in double field theory. After
+rederiving the general form of these fluxes, we consider the proposed flux
+induced four-dimensional effective superpotential and oxidize its induced
+scalar potential to terms in a ten-dimensional action. This analysis is
+performed independently for an explicit toroidal type IIA and its T-dual type
+IIB orientifold. We show in detail that the result of this bottom-up approach
+is compatible with the gauged supergravity motivated flux formulation of the
+double field theory action in both the NS-NS and the R-R sector.",1306.2761v3
+2013-06-20,Limitations of the hybrid functional approach to electronic structure of transition metal oxides,"During the last decade, ab initio methods to calculate electronic structure
+of materials based on hybrid functionals are increasingly becoming widely
+popular. In this Letter, we show that, in the case of small gap transition
+metal oxides, such as VO2, with rather subtle physics in the vicinity of the
+Fermi-surface, such hybrid functional schemes without the inclusion of
+""expensive"" fully self-consistent GW corrections fail to yield this physics and
+incorrectly describe the features of the wave function of states near the
+Fermi-surface. While a fully self-consistent GW on top of hybrid functional
+approach does correct these wave functions as expected, and is found to be in
+general agreement with the results of a fully self-consistent GW approach based
+on semilocal functionals, it is much more computationally demanding as compared
+to the latter approach for the benefit of essentially the same results.",1306.4948v1
+2013-06-24,Electron-electron scatttering in Sn-doped indium oxide thick films,"We have measured the low-field magnetoresistances (MRs) of a series of
+Sn-doped indium oxide thick films in the temperature $T$ range 4--35 K. The
+electron dephasing rate $1/\tau_{\varphi}$ as a function of $T$ for each film
+was extracted by comparing the MR data with the three-dimensional (3D)
+weak-localization theoretical predictions. We found that the extracted
+$1/\tau_{\varphi}$ varies linearly with $T^{3/2}$. Furthermore, at a given $T$,
+$1/\tau_{\varphi}$ varies linearly with $k_F^{-5/2}l^{-3/2}$, where $k_{F}$ is
+the Fermi wavenumber, and $l$ is the electron elastic mean free path. These
+features are well explained in terms of the small-energy-transfer
+electron-electron scattering time in 3D disordered conductors. This electron
+dephasing mechanism dominates over the electron-phonon ($e$-ph) scattering
+process because the carrier concentrations in our films are $\sim$ 3 orders of
+magnitude lower than those in typical metals, which resulted in a greatly
+suppressed $e$-ph relaxation rate.",1306.5610v1
+2013-07-02,Energy ordering of grain boundaries in Cr2O3: Insights from theory,"The grain boundaries, GBs, of corundum Cr2O3 are known to play an important
+role in the diffusion of ions within the oxide, which is an important
+phenomenon for the corrosion of the stainless steels. The extent of the growth
+of oxide layers in stainless steel depends upon which interfaces are preferred
+within Cr2O3. Therefore, we have constructed four different grain boundary
+planes (rhombohedral, basal, prismatic and pyramidal) and their various
+associated interface symmetries known in literature for corundum Al2O3. Their
+structural, electronic, and energetic properties are investigated theoretically
+with periodic calculations using the DFT+U approach. We find that the prismatic
+screw GB with a Cr-O plane interface is the energetically preferred GB with the
+rhombohedral GB with screw symmetry and Cr vacancy termination being the second
+energetically preferred GB. The increase of the number of in-plane Cr atoms at
+the interface of prismatic GB enhances the stability which is also evident in
+the electronic density of states.",1307.0691v1
+2013-07-11,Lanthanide impurities in wide bandgap semiconductors: a possible roadmap for spintronic devices,"The electronic properties of lanthanide (from Eu to Tm) impurities in
+wurtzite gallium nitride and zinc oxide were investigated by first principles
+calculations, using an all electron methodology plus a Hubbard potential
+correction. The results indicated that the 4f-related energy levels remain
+outside the bandgap in both materials, in good agreement with a recent
+phenomenological model, based on experimental data. Additionally, zinc oxide
+doped with lanthanide impurities became an n-type material, showing a coupling
+between the 4f-related spin polarized states and the carriers. This coupling
+may generate spin polarized currents, which could lead to applications in
+spintronic devices.",1307.3209v1
+2013-07-15,Doping-Induced Spectral Shifts in Two Dimensional Metal Oxides,"Doping of strongly layered ionic oxides is an established paradigm for
+creating novel electronic behavior. This is nowhere more apparent than in
+superconductivity, where doping gives rise to high temperature
+superconductivity in cuprates (hole-doped) and to surprisingly high Tc in HfNCl
+(Tc=25.5K, electron-doped). First principles calculations of hole-doping of the
+layered delafossite CuAlO2 reveal unexpectedly large doping-induced shifts in
+spectral density, strongly in opposition to the rigid band picture that is
+widely used as an accepted guideline. These spectral shifts, of similar origin
+as the charge transfer used to produce negative electron affinity surfaces and
+adjust Schottky barrier heights, drastically alter the character of the Fermi
+level carriers, leading in this material to an O-Cu-O molecule-based carrier
+(or polaron, at low doping) rather than a nearly pure-Cu hole as in a rigid
+band picture. First principles linear response electron-phonon coupling (EPC)
+calculations reveal, as a consequence, net weak EPC and no superconductivity
+rather than the high Tc obtained previously using rigid band expectations.
+These specifically two-dimensional dipole-layer driven spectral shifts provides
+new insights into materials design in layered materials foe functionalities
+besides superconductivity.",1307.4126v1
+2013-07-16,First-principles thermodynamic screening approach to photo-catalytic water splitting with co-catalysts,"We adapt the computational hydrogen electrode approach to explicitly account
+for photo-generated charges and use it to computationally screen for viable
+catalyst/co-catalyst combinations for photo-catalytic water splitting. The hole
+energy necessary to thermodynamically drive the reaction is employed as
+descriptor for the screening process. Using this protocol and hybrid-level
+density-functional theory we show that water oxidation on bare TiO2 surfaces is
+thermodynamically more complex than previously thought. This motivates a
+screening for suitable co-catalysts for this half-reaction, which we carry out
+for Au particles down to the non-scalable size regime. We find that almost all
+small Au clusters studied are better suited for water photo-oxidation than an
+extended Au(111) surface or bare TiO2 facets.",1307.4199v1
+2013-07-18,Structural position and oxidation state of nickel in SrTiO3,"The properties of Ni-doped strontium titanate are studied using X-ray
+diffraction and XAFS spectroscopy. It is shown that regardless of the
+preparation conditions, the SrTi1-xNixO3 solid solution and the NiTiO3 phase
+are the most stable phases which can coexist. According to the EXAFS data, in
+the single-phase sample of SrTi0.97Ni0.03O3, the Ni atoms substitute for the Ti
+ones and are on-center. The distortion of the oxygen octahedra is not observed.
+The XANES spectra analysis shows that the oxidation state of nickel in NiTiO3
+is 2+, and in the SrTi1-xNixO3 solid solution it is close to 4+. It is shown
+that the strongest light absorption in doped samples is associated with the
+presence of tetravalent nickel in the SrTi1-xNixO3 solid solution. This doping
+seems the most promising one for solar energy converters that exploit the bulk
+photovoltaic effect.",1307.5082v2
+2013-07-24,Evolutionary search for new high-k dielectric materials: methodology and applications to hafnia-based oxides,"High-k dielectric materials are important as gate oxides in microelectronics
+and as potential dielectrics for capacitors. In order to enable computational
+discovery of novel high-k dielectric materials, we propose a fitness model
+(energy storage density) that includes the dielectric constant, bandgap, and
+intrinsic breakdown field. This model, used as fitness function in conjunction
+with first-principles calculations and global optimization evolutionary
+algorithm USPEX, efficiently leads to practically important results. We found a
+number of high-fitness structures of SiO2 and HfO2, some of which correspond to
+known phases and some are new. The results allow us to propose characteristics
+(genes) common to high-fitness structures - these are the coordination
+polyhedra and their degree of distortion. Our variable-composition searches in
+the HfO2-SiO2 system uncovered several high-fitness states. This hybrid
+algorithm opens up a new avenue of discovering novel high-k dielectrics with
+both fixed and variable compositions, and will speed up the process of
+materials discovery.",1307.6358v2
+2013-10-04,Designing a robustly metallic noncenstrosymmetric ruthenate oxide with large thermopower anisotropy,"The existence of approximately 30 noncentrosymmetric metals (NCSM) suggests a
+contraindication between crystal structures without inversion symmetry and
+metallic behavior. Those containing oxygen are especially scarce. Here we
+propose and demonstrate a design framework to remedy this property disparity
+and accelerate NCSM-oxide discovery: The primary ingredient relies on the
+removal of inversion symmetry through displacements of atoms whose electronic
+degrees of freedom are decoupled from the states at the Fermi level. Density
+functional theory calculations validate this crystal--chemistry strategy, and
+we predict a new polar ruthenate exhibiting robust metallicity. We demonstrate
+that the electronic structure is unaffected by the inclusion of spin-orbit
+interactions (SOI), and that cation ordered SrCaRu$_2$O$_6$ exhibits a large
+thermopower anisotropy ($\left|\Delta\mathcal{S}_\perp\right|\sim6.3 \mu
+\textrm{V K}^{-1}$ at 300 K) derived from its polar structure. Our findings
+provide chemical and structural selection guidelines to aid in the search of
+new NCS metals with enhanced thermopower anisotropy.",1310.1148v2
+2013-10-04,Covalency in transition metal oxides within all-electron Dynamical Mean Field Theory,"A combination of dynamical mean field theory and density functional theory,
+as implemented in Phys. Rev. B 81, 195107 (2010), is applied to both the early
+and late transition metal oxides. For fixed value of the local Coulomb
+repulsion, without fine tuning, we obtain the main features of these series,
+such as the metallic character of SrVO$_3$ and the the insulating gaps of
+LaVO$_3$, LaTiO$_3$ and La$_2$CO$_4$ which are in good agreement with
+experiment. The study highlights the importance of local physics and high
+energy hybridization in the screening of the Hubbard interaction and how
+different low energy behaviors can emerge from the a unified treatment of the
+transition metal series.",1310.1158v2
+2013-10-09,Emergent topological and half semimetallic Dirac Fermions at oxide interfaces,"It is highly desirable to combine recent advances in the topological quantum
+phases with technologically relevant materials. Chromium dioxide (CrO2) is a
+half-metallic material, widely used in high-end data storage applications.
+Using first principles calculations, we show via interfacial orbital design
+that a novel class of half semi-metallic Dirac electronic phase emerges at the
+interface CrO2 with TiO2 in both thin film and superlattice configurations,
+with four spin-polarized Dirac points in momentum-space (k-space) band
+structure. When the spin and orbital degrees of freedom are allowed to couple,
+the CrO2/TiO2 superlattice becomes a Chern insulator without external fields or
+additional doping. With topological gaps equivalent to 43 Kelvin and a Chern
+number 2, the ensuing quantization of Hall conductance to 2e^2/h will enable
+potential development of these highly industrialized oxides for applications in
+topologically high fidelity data storage and energy-efficient electronic and
+spintronic devices.",1310.2471v1
+2013-10-14,Non-volatile multilevel resistive switching memory cell: A transition metal oxide-based circuit,"We study the resistive switching (RS) mechanism as way to obtain multi-level
+memory cell (MLC) devices. In a MLC more than one bit of information can be
+stored in each cell. Here we identify one of the main conceptual difficulties
+that prevented the implementation of RS-based MLCs. We present a method to
+overcome these difficulties and to implement a 6-bit MLC device with a
+manganite-based RS device. This is done by precisely setting the remnant
+resistance of the RS-device to an arbitrary value. Our MLC system demonstrates
+that transition metal oxide non-volatile memories may compete with the
+currently available MLCs.",1310.3613v1
+2013-10-17,Designing heavy metal oxide glasses with threshold properties from network rigidity,"Here we show that a new class of glasses composed of heavy metal oxides
+involving transition metals (V$_\text {2}$O$_\text{}$5-TeO$_\text{2}$), can
+surprisingly be designed from very basic tools using topology and rigidity of
+their underlying molecular networks. When investigated as a function of
+composition, such glasses display abrupt changes in network packing and
+enthalpy of relaxation at Tg, underscoring presence of flexible to rigid
+elastic phase transitions. We find that these elastic phases are fully
+consistent with polaronic nature of electronic conductivity at high
+V$_\text{2}$O$_\text{5}$ content. Such observations have new implications for
+designing electronic glasses which differ from the traditional amorphous
+electrolytes having only mobile ions as charge carriers.",1310.4789v1
+2013-10-22,Inhomogeneity of donor doping in SrTiO3 substrates studied by fluorescence-lifetime imaging microscopy,"Fluorescence-lifetime imaging microscopy (FLIM) was applied to investigate
+the donor distribution in SrTiO3 single crystals. On the surfaces of Nb- and
+La-doped SrTiO3, structures with different fluorescence intensities and
+lifetimes were found that could be related to different concentrations of Ti3+.
+Furthermore, the inhomogeneous distribution of donors caused a non-uniform
+conductivity of the surface, which complicates the production of potential
+electronic devices by the deposition of oxide thin films on top of doped single
+crystals. Hence, we propose FLIM as a convenient technique (length scale: 1
+$\mu$m) for characterizing the quality of doped oxide surfaces, which could
+help to identify appropriate substrate materials.",1310.5813v1
+2013-11-04,Artificial Synapse Network on Inorganic Proton Conductor for Neuromorphic Systems Applications,"The basic units in our brain are neurons and each neuron has more than 1000
+synapse connections. Synapse is the basic structure for information transfer in
+an ever-changing manner, and short-term plasticity allows synapses to perform
+critical computational functions in neural circuits. Therefore the major
+challenge for the hardware implementation of neuromorphic computation is to
+develop artificial synapse. Here, in-plane oxide-based artificial synapse
+network coupled by proton neurotransmitters are self-assembled on glass
+substrates at room-temperature. A strong lateral modulation is observed due to
+the proton migration in the nanogranular phosphorus-doped SiO2 electrolyte
+films. Functional roles of short-term plasticity, including paired-pulse
+facilitation, dynamic filtering and spatiotemporally correlated signal
+processing are mimicked. Such in-plane oxide-based protonic/electronic hybrid
+synapse network proposed here are interesting for building future neuromorphic
+systems.",1311.0559v1
+2013-11-05,Spin accumulation detection of FMR driven spin pumping in silicon-based metal-oxide-semiconductor heterostructures,"The use of the spin Hall effect and its inverse to electrically detect and
+manipulate dynamic spin currents generated via ferromagnetic resonance (FMR)
+driven spin pumping has enabled the investigation of these dynamically injected
+currents across a wide variety of ferromagnetic materials. However, while this
+approach has proven to be an invaluable diagnostic for exploring the spin
+pumping process it requires strong spin-orbit coupling, thus substantially
+limiting the materials basis available for the detector/channel material
+(primarily Pt, W and Ta). Here, we report FMR driven spin pumping into a weak
+spin-orbit channel through the measurement of a spin accumulation voltage in a
+Si-based metal-oxide-semiconductor (MOS) heterostructure. This alternate
+experimental approach enables the investigation of dynamic spin pumping in a
+broad class of materials with weak spin-orbit coupling and long spin lifetime
+while providing additional information regarding the phase evolution of the
+injected spin ensemble via Hanle-based measurements of the effective spin
+lifetime.",1311.0965v1
+2013-11-10,A Nanoscale Shape Memory Oxide,"Stimulus-responsive shape memory materials have attracted tremendous research
+interests recently, with much effort focused on improving their mechanical
+actuation. Driven by the needs of nanoelectromechnical devices, materials with
+large mechanical strain particularly at nanoscale are therefore desired. Here
+we report on the discovery of a large shape memory effect in BiFeO3 at the
+nanoscale. A maximum strain of up to ~14% and a large volumetric work density
+can be achieved in association with a martensitic-like phase transformation.
+With a single step, control of the phase transformation by thermal activation
+or electric field has been reversibly achieved without the assistance of
+external recovery stress. Although aspects such as hysteresis, micro-cracking
+etc. have to be taken into consideration for real devices, the large shape
+memory effect in this oxide surpasses most alloys and therefore demonstrates
+itself as an extraordinary material for potential use in state-of-art
+nano-systems.",1311.2243v1
+2013-11-11,A first principles study of As doping at a disordered Si--SiO$_2$ interface,"Understanding the interaction between dopants and semiconductor-oxide
+interfaces is an increasingly important concern in the drive to further
+miniaturize modern transistors. To this end, using a combination of
+first-principles density-functional theory and a continuous random network
+Monte Carlo method, we investigate electrically active arsenic donors at the
+interface between silicon and its oxide. Using a realistic model of the
+disordered interface, we find that a small percentage (on the order of ~10%) of
+the atomic sites in the first few monolayers on the silicon side of the
+interface are energetically favourable for segregation, and that this is
+controlled by the local bonding and local strain of the defect centre. We also
+find that there is a long-range quantum confinement effect due to the
+interface, which results in an energy barrier for dopant segregation, but that
+this barrier is small in comparison to the effect of the local environment.
+Finally, we consider the extent to which the energetics of segregation can be
+controlled by the application of strain to the interface.",1311.2480v1
+2013-11-12,Realizing Chemical Codoping in Oxide Semiconductors,"We demonstrate experimentally a chemical codoping approach that would
+simultaneously narrow the band gap and control the band edge positions of oxide
+semiconductors. Using TiO2 as an example, we show that a sequential doping
+scheme with nitrogen (N) leading the way, followed by phosphorous (P), is
+crucial for the incorporation of both N and P into the anion sites. Various
+characterization techniques confirm the formation of the N-P bonds, and as a
+consequence of the chemical codoping, the band gap of the TiO2 is reduced from
+3.0 eV to 1.8 eV. The realization of chemical codoping could be an important
+step forward in improving the general performance of electronic and
+optoelectronic materials and devices.",1311.2779v1
+2013-11-15,Transport properties of Ag5Pb2O6: a three-dimensional electron-gas-like system with low-carrier-density,"We report normal-state transport properties of the single-crystalline samples
+of the silver-lead oxide superconductor Ag5Pb2O6, including the electrical
+resistivity, magnetoresistance, and Hall coefficient. From the Hall coefficient
+measurement, we confirmed that the carrier density of this oxide is as low as
+5x10^{21} cm^{-3}, one order of magnitude smaller than those for ordinary
+alkali metals and noble metals. The magnetoresistance behavior is well
+characterized by the axial symmetry of the Fermi surface and by a single
+relaxation time. The T^2 term of the resistivity is scaled with the specific
+heat coefficient, based on the recent theory for the electron-electron
+scattering. The present results provide evidence that Ag5Pb2O6 is a
+low-carrier-density three-dimensional electron-gas-like system with enhanced
+electron-electron scatterings.",1311.3860v1
+2013-11-19,Charge transfer satellites in x-ray spectra of transition metal oxides,"Strongly correlated materials such as transition metal oxides (TMOs) often
+exhibit large satellites in their x-ray photoemission (XPS) and x-ray
+absorption spectra (XAS). These satellites arise from localized charge-transfer
+(CT) excitations that accompany the sudden creation of a core hole. Here we use
+a two-step approach to treat such excitations in a localized system embedded in
+a condensed system and coupled to a photoelectron. The total XAS is then given
+by a convolution of a spectral function representing the localized excitations
+and the XAS of the extended system. The local system is modeled roughly in
+terms of a simple three-level model, leading to a double-pole approximation for
+the spectral function that represents dynamically weighted contributions from
+the dominant neutral and charge-transfer excitations. This method is
+implemented using a resolvent approach, with potentials, radial wave-functions
+and matrix elements from the real-space Green's function code FEFF, and
+parameters fitted to XPS experiments. Representative calculations for several
+TMOs are found to be in reasonable agreement with experiment.",1311.4910v1
+2013-12-10,Importance of d-p Coulomb interaction for high T$_C$ cuprates and other oxides,"Current theoretical studies of electronic correlations in transition metal
+oxides typically only account for the local repulsion between d-electrons even
+if oxygen ligand p-states are an explicit part of the effective Hamiltonian.
+Interatomic interactions such as Upd between d- and (ligand) p-electrons, as
+well as the local interaction between p-electrons, are neglected. Often, the
+relative d-p orbital splitting has to be adjusted ""ad hoc"" on the basis of the
+experimental evidence. By applying the merger of local density approximation
+and dynamical mean field theory (LDA+DMFT) to the prototypical case of the
+3-band Emery dp model for the cuprates, we demonstrate that, without any ""ad
+hoc"" adjustment of the orbital splitting, the charge transfer insulating state
+is stabilized by the interatomic interaction Upd. Our study hence shows how to
+improve realistic material calculations that explicitly include the p-orbitals.",1312.2757v1
+2014-01-10,Combined therapies of antithrombotics and antioxidants delay in silico brain tumor progression,"Glioblastoma multiforme, the most frequent type of primary brain tumor, is a
+rapidly evolving and spatially heterogeneous high-grade astrocytoma that
+presents areas of necrosis, hypercellularity and microvascular hyperplasia. The
+aberrant vasculature leads to hypoxic areas and results in an increase of the
+oxidative stress selecting for more invasive tumor cell phenotypes. In our
+study we assay in silico different therapeutic approaches which combine
+antithrombotics, antioxidants and standard radiotherapy. To do so, we have
+developed a biocomputational model of glioblastoma multiforme that incorporates
+the spatio-temporal interplay among two glioma cell phenotypes corresponding to
+oxygenated and hypoxic cells, a necrotic core and the local vasculature whose
+response evolves with tumor progression. Our numerical simulations predict that
+suitable combinations of antithrombotics and antioxidants may diminish, in a
+synergetic way, oxidative stress and the subsequent hypoxic response. This
+novel therapeutical strategy, with potentially low or no toxicity, might reduce
+tumor invasion and further sensitize glioblastoma multiforme to conventional
+radiotherapy or other cytotoxic agents, hopefully increasing median patient
+overall survival time.",1401.2397v1
+2014-01-14,Precise and ultrafast molecular sieving through graphene oxide membranes,"There has been intense interest in filtration and separation properties of
+graphene-based materials that can have well-defined nanometer pores and exhibit
+low frictional water flow inside them. Here we investigate molecular permeation
+through graphene oxide laminates. They are vacuum-tight in the dry state but,
+if immersed in water, act as molecular sieves blocking all solutes with
+hydrated radii larger than 4.5A. Smaller ions permeate through the membranes
+with little impedance, many orders of magnitude faster than the diffusion
+mechanism can account for. We explain this behavior by a network of
+nanocapillaries that open up in the hydrated state and accept only species that
+fit in. The ultrafast separation of small salts is attributed to an 'ion
+sponge' effect that results in highly concentrated salt solutions inside
+graphene capillaries.",1401.3134v1
+2014-01-31,Observation of strontium segregation in LaAlO$_{3}$/SrTiO$_{3}$ and NdGaO$_{3}$/SrTiO$_{3}$ oxide heterostructures by X-ray photoemission spectroscopy,"LaAlO$_{3}$ and NdGaO$_{3}$ thin films of different thickness have been grown
+by pulsed laser deposition on TiO$_2$-terminated SrTiO$_{3}$ single crystals
+and investigated by soft X-ray photoemission spectroscopy. The surface
+sensitivity of the measurements has been tuned by varying photon energy $h\nu$
+and emission angle $\Theta$. In contrast to the core levels of the other
+elements, the Sr $3d$ line shows an unexpected splitting for higher surface
+sensitivity, signaling the presence of a second strontium component. From our
+quantitative analysis we conclude that during the growth process Sr atoms
+diffuse away from the substrate and segregate at the surface of the
+heterostructure, possibly forming strontium oxide.",1401.8165v1
+2014-04-04,Atomically precise interfaces from non-stoichiometric deposition,"Complex oxide heterostructures display some of the most chemically abrupt,
+atomically precise interfaces, which is advantageous when constructing new
+interface phases with emergent properties by juxtaposing incompatible ground
+states. One might assume that atomically precise interfaces result from
+stoichiometric growth, but here we show that the most precise control is
+obtained for non-stoichiometric growth where differing surface energies can be
+compensated by surfactant-like effects. For the precise growth of
+Sr$_{n+1}$Ti$_n$O$_{3n+1}$ Ruddlesden-Popper (RP) phases, stoichiometric
+deposition leads to the loss of the first RP rock-salt double layer, but
+growing with a strontium-rich surface layer restores the bulk stoichiometry and
+ordering of the subsurface RP structure. Our results dramatically expand the
+materials that can be prepared in epitaxial heterostructures with precise
+interface control---from just the $n=\infty$ end members (perovskites) to the
+entire RP family---enabling the exploration of novel quantum phenomena at a
+richer variety of oxide interfaces.",1404.1374v1
+2014-04-06,Piezoelectric properties of graphene oxide from the first-principles calculations,"Some highly ordered compounds of graphene oxide (GO), e.g., the so-called
+clamped and unzipped GO, are shown to have piezoelectric responses via
+first-principles density functional calculations. By applying an electric field
+perpendicular to the GO basal plane, the largest value of in-plane strain and
+strain piezoelectric coefficient, d31 are found to be 0.12% and 0.24 pm/V,
+respectively, which are comparable with those of some advanced piezoelectric
+materials. An in-depth molecular structural analysis reveals that deformation
+of the oxygen doping regions in the clamped GO dominates its overall strain
+output, whereas deformation of the regions without oxygen dopant in the
+unzipped GO determines its overall piezoelectric strain. This understanding
+explains the observed dependence of d31 on oxygen doping rate, i.e., higher
+oxygen concentration giving rise to a larger d31 in the clamped GO whereas
+leading to a reduced d31 in the unzipped GO. As the thinnest two-dimensional
+piezoelectric materials, GO has a great potential for a wide range of MEMS/NEMS
+actuators and sensors.",1404.1635v1
+2014-04-08,Electron-beam patterning of polymer electrolyte films to make multiple nanoscale gates for nanowire transistors,"We report an electron-beam based method for the nanoscale patterning of the
+poly(ethylene oxide)/LiClO$_{4}$ polymer electrolyte. We use the patterned
+polymer electrolyte as a high capacitance gate dielectric in single nanowire
+transistors and obtain subthreshold swings comparable to conventional
+metal/oxide wrap-gated nanowire transistors. Patterning eliminates gate/contact
+overlap which reduces parasitic effects and enables multiple, independently
+controllable gates. The method's simplicity broadens the scope for using
+polymer electrolyte gating in studies of nanowires and other nanoscale devices.",1404.1975v1
+2014-04-13,Vector rectangular-shape laser based on reduced graphene oxide interacting with long fiber taper,"A vector dual-wavelength rectangular-shape laser (RSL) based on a long fiber
+taper deposited with reduced graphene oxide is proposed, where the nonlinearity
+is enhanced due to large evanescent-field-interacting length and strong field
+confinement of a 8 mm fiber taper with a waist diameter of 4 micronmeters.
+Graphene flakes are deposited uniformly on the taper waist with light pressure
+effect, so this structure guarantees both excellent saturable absorption and
+high nonlinearity. The RSL with a repetition rate of 7.9 MHz exhibits fast
+polarization switching in two orthogonal polarization directions, and the
+temporal and spectral characteristics are investigated. The results suggest
+that the long taper-based graphene structure is an efficient choice for
+nonlinear devices.",1404.3400v1
+2014-04-15,Topological superconductivity and unconventional pairing in oxide interfaces,"To pinpoint the microscopic mechanism for superconductivity has proven to be
+one of the most outstanding challenges in the physics of correlated quantum
+matter. Thus far, the most direct evidence for an electronic pairing mechanism
+is the observation of a new symmetry of the order-parameter, as done in the
+cuprate high-temperature superconductors. Like distinctions based on the
+symmetry of a locally defined order-parameter, global, topological invariants
+allow for a sharp discrimination between states of matter that cannot be
+transformed into each other adiabatically. Here we propose an unconventional
+pairing state for the electron fluid in two-dimensional oxide interfaces and
+establish a direct link to the emergence of nontrivial topological invariants.
+Topological superconductivity and Majorana edge states can then be used to
+detect the microscopic origin for superconductivity. In addition, we show that
+also the density wave states that compete with superconductivity sensitively
+depend on the nature of the pairing interaction. Our conclusion is based on the
+special role played by the spin-orbit coupling and the shape of the Fermi
+surface in SrTiO$_{3}$/LaAlO$_{3}$-interfaces and closely related systems.",1404.4039v1
+2014-04-17,Pico- and nanosecond laser ablation of mixed tungsten / aluminium films,"In order to extend the investigation of laser-assisted cleaning of
+ITER-relevant first mirror materials to the picosecond regime, a commercial
+laser system delivering 10 picosecond pulses at 355 nm at a frequency of up to
+1 MHz has been used to investigate the ablation of mixed aluminium (oxide) /
+tungsten (oxide) layers deposited on poly- and nanocrystalline molybdenum as
+well as nanocrystalline rhodium mirrors. Characterization before and after
+cleaning using scanning electron microscopy (SEM) and spectrophotometry shows
+heavy dust formation, resulting in a degradation of the reflectivity. Cleaning
+using a 5 nanosecond pulses at 350 and 532 nm, on the other hand, proved very
+promising. The structure of the film remnants suggests that in this case
+buckling was the underlying removal mechanism rather than ablation. Repeated
+coating and cleaning using nanosecond pulses is demonstrated.",1404.4494v1
+2014-07-02,Effects of carbon nanotubes and graphene oxide absorbers on the noise of mode-locked fiber lasers,"Phase noise is very important for the ultrafast pulse application in
+telecommunication, ultrafast diagnose, material science, and biology. In this
+paper, two types of carbon nano-materials, single-wall carbon nanotube and
+graphene oxide, are investigated for noise suppression in ultrafast photonics.
+Various properties of the wall-paper SAs, such as saturable intensity, optical
+absorption and degree of purity, are found to be key factors determining the
+phase noise of the ultrafast pulses. A reduced-noise femtosecond fiber laser is
+experimentally demonstrated by optimizing the above parameters of carbon
+material based SAs. The phase noise reduction more than 10 dB at 10 kHz can be
+obtained in the experiments. To our knowledge, this is the first time that the
+relationship between different carbon material based SAs and the phase noise of
+mode-locked lasers has been investigated. This work will pave the way to get a
+high-quality ultrashort pulse in passively mode-locked fiber lasers.",1407.0507v1
+2014-07-02,Giant Rydberg Excitons in Cuprous Oxide,"Highly excited atoms with an electron moved into a level with large principal
+quantum number are fascinating hydrogen-like objects. The giant extension of
+these Rydberg atoms leads to huge interaction effects. Monitoring these
+interactions has provided novel insights into molecular and condensed matter
+physics problems on a single quantum level. Excitons, the fundamental optical
+excitations in semiconductors consisting of a negatively charged electron and a
+positively charged hole, are the condensed matter analogues of hydrogen. Highly
+excited excitons with extensions similar to Rydberg atoms are attractive
+because they may be placed and moved in a crystal with high precision using
+microscopic potential landscapes. Their interaction may allow formation of
+ordered exciton phases or sensing of elementary excitations in the surrounding,
+also on a quantum level. Here we demonstrate the existence of Rydberg excitons
+in cuprous oxide, Cu2O, with principal quantum numbers as large as n=25 . These
+states have giant wave function extensions of more than 2 micrometers, compared
+to about a nanometer for the ground state. The strong dipole-dipole interaction
+is evidenced by a blockade effect, where the presence of an exciton prevents
+excitation of a further exciton in its vicinity.",1407.0691v1
+2014-07-11,Microstructure-dependent oxidation-assisted dealloying of Cu0.7Al0.3 thin films,"In this paper, the oxidation-assisted dealloying (OAD) of Cu0.7Al0.3 films
+with different microstructures which were obtained by high vacuum annealing at
+different temperatures were studied using powder X-ray diffraction,
+field-emission scanning electron microscopy and energy dispersive X-ray
+analysis. It was observed that different microstructures such as eutectic
+mixture or solid solution, the grain size of Cu or Al component in
+eutectic-mixture Cu0.7Al0.3 films affected the corrosion morphology greatly. It
+thus provided a practical route to fabricate flexible CuO porous
+nanostructure-films (PNFs) with controllable pore size, porosity, block size
+and shape. Further, the underlying OAD mechanisms for the structure-resultant
+different corrosion morphologies of Cu0.7Al0.3 films were also explored. In
+these senses, the study is suggestive and crucial to both the mechanism
+understanding of OAD process and the technical controlling of PNF fabrication.",1407.3131v2
+2014-07-14,Insights and challenges of applying the $GW$ method to transition metal oxides,"The ab initio $GW$ method is considered as the most accurate approach for
+calculating the band gaps of semiconductors and insulators. Yet its application
+to transition metal oxides (TMOs) has been hindered by the failure of
+traditional approximations developed for conventional semiconductors. In this
+work, we examine the effects of these approximations on the values of band gaps
+for ZnO, Cu$_2$O, and TiO$_2$. In particular, we explore the origin of the
+differences between the two widely used plasmon-pole models. Based on the
+comparison of our results with the experimental data and previously published
+calculations, we discuss which approximations are suitable for TMOs and why.",1407.3781v5
+2014-07-24,Path of the current flow at the metal contacts of graphene field-effect transistors with distorted transfer characteristics,"Graphene field-effect transistors with source/drain contacts made of metals
+that can be easily oxidized such as ferromagnetic metals often display a double
+dip structure in the transfer characteristics because of charge density
+depinning at the contacts. Generally, transfer characteristics of field-effect
+transistors show no dependence on the length of the source/drain contacts
+because charge carrier injection occurs mainly at the edges of the contact.
+However, the shape of the transfer characteristics of devices fabricated using
+Ni contacts is found to be dependent on the length of the contact. This
+peculiar behavior was attributed to charge carrier injection from near the
+center of the contacts. This is because of oxygen diffusion and the resultant
+formation of an interfacial oxide layer of non-uniform thickness. The observed
+contact length dependent transfer characteristics were reproduced using a model
+calculation that includes charge carrier injection from the center of the
+electrode and subsequent charge transport underneath the metal contact.",1407.6754v1
+2014-08-01,Charge transfer across transition metal oxide interfaces: emergent conductance and new electronic structure,"We perform density functional theory plus dynamical mean field theory
+calculations to investi- gate internal charge transfer in an artificial
+superlattice composed of alternating layers of vanadate and manganite
+perovskite and Ruddlesden-Popper structure materials. We show that the elec-
+tronegativity difference between vanadium and manganese causes moderate charge
+transfer from VO2 to MnO2 layers in both perovskite and Ruddlesden-Popper based
+superlattices, leading to hole doping of the VO2 layer and electron doping of
+the MnO2 layer. Comparison of the perovskite and Ruddlesden-Popper based
+heterostructures provides insights into the role of the apical oxy- gen. Our
+first principles simulations demonstrate that the combination of internal
+charge transfer and quantum confinement provided by heterostructuring is a
+powerful approach to engineering electronic structure and tailoring correlation
+effects in transition metal oxides.",1408.0217v2
+2014-08-02,Exfoliating pristine black phosphorus down to the monolayer: photo-oxidation and electronic confinement effects,"Thin layers of black phosphorus have recently raised interest for their
+two-dimensional (2D) semiconducting properties, such as tunable direct bandgap
+and high carrier mobilities. This lamellar crystal of P atoms stacked together
+by weak van der Waals forces can be exfoliated down to the stratophosphane
+monolayer (also called phosphorene) using procedures similar to those used for
+graphene. Properties of this 2D material are however challenging to probe due
+to a fast and ubiquitous degradation upon exposure to ambient conditions.
+Herein, we investigate the crystal degradation using in-situ Raman and
+transmission electron spectroscopies and highlight a process involving a
+photo-induced oxidation reaction with adsorbed oxygen in water. The
+experimental conditions to prepare and preserve mono-, bi- and multilayers of
+stratophosphane in their pristine states were determined. Study on these 2D
+layers provides new insights on the effect of confinement on the chemical
+reactivity and the vibrational modes of black phosphorus.",1408.0345v2
+2014-08-11,Importance of tetrahedral coordination for high-valent transition metal oxides: YCrO$_4$ as a model system,"We have investigated the electronic structure of the high oxidation state
+material YCrO$_4$ within the framework of the Zaanen-Sawatzky-Allen phase
+diagram. While Cr$^{4+}$-based compounds like SrCrO$_3$/CaCrO$_3$ and CrO$_2$
+can be classified as small-gap or metallic negative-charge-transfer systems, we
+find using photoelectron spectroscopy that YCrO$_4$ is a robust insulator
+despite the fact that its Cr ions have an even higher formal valence state of
+5+. We reveal using band structure calculations that the tetrahedral
+coordination of the Cr$^{5+}$ ions in YCrO$_4$ plays a decisive role, namely to
+diminish the bonding of the Cr $3d$ states with the top of the O $2p$ valence
+band. This finding not only explains why the charge-transfer energy remains
+effectively positive and the material stable, but also opens up a new route to
+create doped carriers with symmetries different from those of other
+transition-metal ions.",1408.2396v1
+2014-08-18,Breakdown voltage of metal-oxide resistors in liquid argon,"We characterized a sample of metal-oxide resistors and measured their
+breakdown voltage in liquid argon by applying high voltage (HV) pulses over a 3
+second period. This test mimics the situation in a HV-divider chain when a
+breakdown occurs and the voltage across resistors rapidly rise from the static
+value to much higher values. All resistors had higher breakdown voltages in
+liquid argon than their vendor ratings in air at room temperature. Failure
+modes range from full destruction to coating damage. In cases where breakdown
+was not catastrophic, subsequent breakdown voltages were lower in subsequent
+measuring runs. One resistor type withstands 131\,kV pulses, the limit of the
+test setup.",1408.4013v4
+2014-08-19,Aluminium-oxide wires for superconducting high kinetic inductance circuits,"We investigate thin films of conducting aluminium-oxide, also known as
+granular aluminium, as a material for superconducting high quality, high
+kinetic inductance circuits. The films are deposited by an optimised reactive
+DC magnetron sputter process and characterised using microwave measurement
+techniques at milli-Kelvin temperatures. We show that, by precise control of
+the reactive sputter conditions, a high room temperature sheet resistance and
+therefore high kinetic inductance at low temperatures can be obtained. For a
+coplanar waveguide resonator with 1.5\,k$\Omega$ sheet resistance and a kinetic
+inductance fraction close to unity, we measure a quality factor in the order of
+700\,000 at 20\,mK. Furthermore, we observe a sheet resistance reduction by
+gentle heat treatment in air. This behaviour is exploited to study the kinetic
+inductance change using the microwave response of a coplanar wave guide
+resonator. We find the correlation between the kinetic inductance and the sheet
+resistance to be in good agreement with theoretical expectations.",1408.4347v3
+2014-09-18,Electrical and optical properties of ITO thin films prepared by DC magnetron sputtering for low-emitting coatings,"Optimized DC magnetron sputtering system for the deposition of transparent
+conductive oxides (TCOs), such indium tin oxide (ITO) on glass substrate has
+been applied in order to achieve low-emitting (low-e) transparent coatings. To
+obtain the concerned electrical resistance and high infrared reflection, first
+the effect of applied sputtering power then oxygen flow on the properties of
+films have been investigated. The other depositions parameters are kept
+constant. Film deposition at at temperature 400 degree of Celsius in oxygen
+flow of 3 Standard Cubic Centimeters per Minute results in transparent and
+infrared reflecting coatings. Under this condition the highest attained average
+reflectance in the infrared is ({\lambda}=3-25 micron) 89.5% (lowest emittance
+equals to less than 11%), whereas transparency in the visible is 85%
+approximately. Plasma wavelength and carrier concentration was measured.",1409.5293v1
+2014-09-23,Superconductivity and its mechanism in an ab initio model for electron-doped LaFeAsO,"Two families of high temperature superconductors whose critical temperatures
+are higher than 50K are known. One is the copper oxides and the other is the
+iron-based superconductors. Comparisons of mechanisms between these two in
+terms of common ground as well as distinctions will greatly help in searching
+for higher Tc superconductors. However, studies on mechanisms for the iron
+family based on first principles calculations are few. Here we first show that
+the superconductivity emerges in the state-of-the-art numerical calculations
+for an ab initio multi-orbital model of an electron-doped iron-based
+superconductor LaFeAsO, in accordance with experimental observations. Then the
+mechanism of the superconductivity is identified as enhanced uniform density
+fluctuations by one-to-one correspondence with the instability toward
+inhomogeneity driven by first-order antiferromagnetic and nematic transitions.
+Despite many differences, certain common features with the copper oxides are
+also figured out in terms of the underlying orbital selective Mottness found in
+the iron family.",1409.6536v1
+2014-09-25,Topological Phases in Oxide Heterostructures with Light and Heavy Transition Metal Ions,"Using a combination of density functional theory, tight-binding models, and
+Hartree-Fock theory, we predict topological phases with and without
+time-reversal symmetry breaking in oxide heterostructures. We consider both
+heterostructures containing light transition metal ions, and those containing
+heavy transition metal ions. We find the (111) growth direction naturally leads
+to favorable conditions for topological phases in both perovskite structures
+and pyrochlore structures. For the case of light transition metal elements,
+Hartree-Fock theory predicts the spin-orbit coupling is effectively enhanced by
+on-site multiple-orbital interactions and may drive the system through a
+topological phase transition, while heavy elements with intrinsically large
+spin-orbit coupling require much weaker, or even vanishing electron
+interactions to bring about a topological phase.",1409.7148v1
+2014-09-25,"Wavelength Spacing Tunable, Multiwavelength Q-switched Fiber Laser Mode-locked by Graphene Oxide","We demonstrate a wavelength spacing tunable, multiwavelength Q-switched
+mode-locked fiber laser (QML) based on a fiber taper deposited with graphene
+oxide. The operation of the laser can be understood in terms of the formation
+of bunches of QMLs which possess small temporal intervals, and multiwavelength
+spectra are generated due to the Fourier transformation. We find that the
+temporal spacing of the QMLs is highly sensitive to the pump power, and as a
+result, the wavelength spacing can be easily tuned by varying the pump power.
+Our experimental laser provides a wavelength spacing tuning range from ~0.001
+nm to 0.145 nm with a pump power variation less than 10 mW. The laser could be
+developed into a low lost wavelength spacing tunable optical source for a wide
+range of applications, such as spectroscopy, microwave/terahertz signal
+generation, optical metrology, optical communications and sensing.",1409.7417v1
+2014-09-26,Structure Evolution of Graphene Oxide during Thermally Driven Phase Transformation: Is the Oxygen Content Really Preserved?,"A mild annealing procedure was recently proposed for the scalable enhancement
+of graphene oxide (GO) properties with the oxygen content preserved, which was
+demonstrated to be attributed to the thermally driven phase separation. In this
+work, the structure evolution of GO with mild annealing is closely
+investigated. It reveals that in addition to phase separation, the
+transformation of oxygen functionalities also occurs, which leads to the slight
+reduction of GO membranes and furthers the enhancement of GO properties. These
+results are further supported by the density functional theory based
+calculations. The results also show that the amount of chemically bonded oxygen
+atoms on graphene decreases gradually and we propose that the strongly
+physisorbed oxygen species constrained in the holes and vacancies on GO lattice
+might be responsible for the preserved oxygen content during the mild annealing
+procedure. The present experimental results and calculations indicate that both
+the diffusion and transformation of oxygen functional groups might play
+important roles in the scalable enhancement of GO properties.",1409.7739v2
+2014-10-08,Resistive switching phenomena in TiOx nanoparticle layers for memory applications,"Electrical characteristics of a Co/TiO_x/Co resistive memory device,
+fabricated by two different methods are reported. In addition to crystalline
+TiO_2 layers fabricated via conventional atomic layer deposition (ALD), an
+alternative method has been examined, where TiO_x nanoparticle layers were
+fabricated via sol-gel. The different devices have shown different hysteresis
+loops with a unique crossing point for the sol-gel devices. A simple
+qualitative model is introduced to describe the different current-voltage
+behaviours by suggesting only one active metal-oxide interface for the ALD
+devices and two active metal-oxide interfaces for the sol-gel devices.
+Furthermore, we show that the resistive switching behaviour could be easily
+tuned by proper interface engineering and that despite having a similar active
+material, different fabrication methods can lead to dissimilar resistive
+switching properties.",1410.2019v1
+2014-10-08,Nanoscale Electrostatic Control of Oxide Interfaces,"We develop a robust and versatile platform to define nanostructures at oxide
+interfaces via patterned top gates. Using LaAlO$_3$/SrTiO$_3$ as a model
+system, we demonstrate controllable electrostatic confinement of electrons to
+nanoscale regions in the conducting interface. The excellent gate response,
+ultra-low leakage currents, and long term stability of these gates allow us to
+perform a variety of studies in different device geometries from room
+temperature down to 50 mK. Using a split-gate device we demonstrate the
+formation of a narrow conducting channel whose width can be controllably
+reduced via the application of appropriate gate voltages. We also show that a
+single narrow gate can be used to induce locally a superconducting to
+insulating transition. Furthermore, in the superconducting regime we see
+indications of a gate-voltage controlled Josephson effect.",1410.2237v2
+2014-10-11,Manganese reduction/oxidation reaction on graphene composites as a reversible process for storing enormous energy at a fast rate,"Oxygen reduction/evolution reaction (ORR/OER) is a basic process for fuel
+cells or metal air batteries. However, ORR/OER generally requires noble metal
+catalysts and suffers from low solubility (10-3 molar per liter) of O2, low
+kinetics rate (10-6 cm2/s) and low reversibility. We report a manganese
+reduction/oxidation reaction (MRR/MOR) on graphene/MnO2 composites, delivering
+a high capacity (4200 mAh/g), fast kinetics (0.0024 cm2/s, three orders higher
+than ORR/OER), high solubility (three orders than O2), and high reversibility
+(100%). We further use MRR/MOR to invent a rechargeable manganese ion battery
+(MIB), which delivers an energy density of 1200 Wh/Kg (several times of lithium
+ion battery), a fast charge ability (3 minutes), and a long cycle life (10,000
+cycles). MRR/MOR renders a new class of energy conversion or storage systems
+with a very high energy density enabling electric vehicles run much more miles
+at one charge.",1410.4223v1
+2014-10-16,Photocatalytic acetaldehyde oxidation in air using spacious TiO2 films prepared by atomic layer deposition on supported carbonaceous sacrificial templates,"Supported carbon nanosheets and carbon nanotubes served as sacrificial
+templates for preparing spacious TiO2 photocatalytic thin films. Amorphous TiO2
+was deposited conformally on the carbonaceous template material by atomic layer
+deposition (ALD). Upon calcination at 550{\deg}C, the carbon template was
+oxidatively removed and the as-deposited continuous amorphous TiO2 layers
+transformed into interlinked anatase nanoparticles with an overall morphology
+commensurate to the original template structure. The effect of type of
+template, number of ALD cycles and gas residence time of pollutant on the
+photocatalytic activity, as well as the stability of the photocatalytic
+performance of these thin films was investigated. The TiO2 films exhibited
+excellent photocatalytic activity towards photocatalytic degradation of
+acetaldehyde in air as a model reaction for photocatalytic indoor air pollution
+abatement. Optimized films outperformed a reference film of commercial PC500.",1410.4405v1
+2014-11-01,Manipulating electronic states at oxide interfaces using focused micro X-rays from standard lab-sources,"Recently, x-ray illumination, using synchrotron radiation, has been used to
+manipulate defects, stimulate self-organization and to probe their structure.
+Here we explore a method of defect-engineering low-dimensional systems using
+focused laboratory-scale X-ray sources. We demonstrate an irreversible change
+in the conducting properties of the 2-dimensional electron gas at the interface
+between the complex oxide materials LaAlO3 and SrTiO3 by X-ray irradiation. The
+electrical resistance is monitored during exposure as the irradiated regions
+are driven into a high resistance state. Our results suggest attention shall be
+paid on electronic structure modification in X-ray spectroscopic studies and
+highlight large-area defect manipulation and direct device patterning as
+possible new fields of application for focused laboratory X-ray sources.",1411.0177v1
+2014-11-21,Structural Modificationand Variation in the Kinetics of Isoconversional Phenomena: A Study on the Effect of Gamma Irradiation on Poly (Ethylene Oxide),"Interactions of Poly (Ethylene Oxide) [PEO] and gamma irradiation of variable
+doses (1-30 kGy) on the thermal, crystalline and structural properties are
+investigated using DSC and FTIR technique. Two states of PEO, viz. powder
+(P-S-series) and solution (P-L-series) are subjected to irradiationand are
+castinto uniform film.DSC results revealed steady increment of crystallinity
+upto 20 kGy for P-S-series after which amorphous region increases till 30 kGy.
+Conversely, P-L-series shows much enhanced crystallinity retained within low
+regime of 7 kGy, followed by sharp declining trend till 30 kGy. DSC is also
+used to determine the multiple kinetic processes in an isoconversional PEO
+melting using Friedman differential analysis. Gamma irradiation is found to
+generate newer functional groups established from FTIR study. FTIR spectra of
+generated peaks viz. -C=O, -C=C- exhibit scission dominated irradiation induced
+in presence of air. Contribution of cross-linkage which is higher in liquid
+irradiation is also proved from FTIR. The studied observations of DSC and FTIR
+are correlated with polymer microstructures. Hence, selective irradiation dose
+could be determined with respect to the exposed state (solid or solution) of
+polymer and utilized to tailor the properties of PEO.",1411.5809v1
+2014-11-26,First Principles Prediction of Topological Phases in Thin Films of Pyrochlore Iridates,"Topological phases have attracted much interest in recent years. While there
+are a number of three-dimensional materials exhibiting topological properties,
+there are relatively few two-dimensional examples aside from the well-known
+quantum Hall systems. Here we make materials-specific predictions for
+topological phases using density functional theory combined with Hartree-Fock
+theory that includes the full orbital structure of the relevant iridum
+$d$-orbitals and the strong but finite spin-orbit coupling strength. We find
+Y$_2$Ir$_2$O$_7$ bilayer and trilayer films grown along the [111] direction can
+support topological metallic phases with a direct gap of up to 0.02 eV, which
+could potentially bring transition metal oxides to the fore as a new class of
+topological materials with potential applications in oxide electronics.",1411.7333v1
+2014-11-30,Two-Dimensional Magnetotransport in a Black Phosphorus Naked Quantum Well,"Black phosphorus (bP) is the second known elemental allotrope with a layered
+crystal structure that can be mechanically exfoliated down to atomic layer
+thickness. We have fabricated bP naked quantum wells in a back-gated field
+effect transistor geometry with bP thicknesses ranging from $6\pm1$ nm to
+$47\pm1$ nm. Using an encapsulating polymer superstrate, we have suppressed bP
+oxidation and have observed field effect mobilities up to 600 cm$^2$/Vs and
+on/off current ratios exceeding $10^5$. Importantly, Shubnikov-de Haas (SdH)
+oscillations observed in magnetotransport measurements up to 35 T reveal the
+presence of a 2-D hole gas with Schr\""odinger fermion character in an
+accumulation layer at the bP/oxide interface. Our work demonstrates that 2-D
+electronic structure and 2-D atomic structure are independent. 2-D carrier
+confinement can be achieved in layered semiconducting materials without
+necessarily approaching atomic layer thickness, advantageous for materials that
+become increasingly reactive in the few-layer limit such as bP.",1412.0259v1
+2014-12-02,Coupling Thermal Integration of a Solid Oxide Fuel Cell with a Magnesium Metal Hydride Tank,"The dehydrogenation behaviour of a cylindrical Mg metal hydride tank is
+simulated and examined in the case where the tank is thermally coupled with an
+operating Solid Oxide Fuel Cell (SOFC) at 7000C. A three-dimensional validated
+mathematical model is utilized to simulate the hydrogen desorption from a
+cylindrical Mg hydride tank. Four scenarios are simulated: a base case where
+the heat source for the desorption process is an external heater surrounding
+the tank. The second case examines the effect of the radiation heat transfer
+from the SOFC to the metal hydride as a possible heat source for the desorption
+procedure. The third scenario uses the exhaust air from the SOFC cathode as the
+heating source which is driven to the hydride and the fourth scenario is a
+combination of both the exhaust air from the SOFC cathode and the external
+heater as the heat source for the desorption. According to the results, the
+exhaust air from the SOFC and the combination of external heater and the
+exhaust heat have a uniform temperature distribution within the tank and
+enhance the desorption capacity.",1412.0878v1
+2014-12-09,Elliptically polarized terahertz radiation from a chiral oxide,"Polarization control of terahertz wave is a challenging subject in terahertz
+science and technology. Here, we report a simple method to control polarization
+state of the terahertz wave in terahertz generation process. At room
+temperature, terahertz radiation from a noncentrosymmetric and chiral oxide,
+sillenite Bi$_{12}$GeO$_{20}$, is observed by the irradiation of linearly
+polarized femtosecond laser pulses at 800 nm. The polarization state of the
+emitted terahertz wave is found to be elliptic with an ellipticity of
+$\sim$0.37$\pm$0.10. Furthermore, the ellipticity was altered to a nearly zero
+($\sim$0.01$\pm$0.01) by changing the polarization of the incident linearly
+polarized femtosecond laser pulses. Such a terahertz radiation characteristic
+is attributable to variation of the polarization state of the emitted terahertz
+waves, which is induced by retardation due to the velocity mismatch between the
+incident femtosecond laser pulse and generated terahertz wave and by the
+polarization tilting due to the optical activity at 800 nm.",1412.2835v1
+2014-12-10,Observation and Structural Control of Charge-Density-Waves resonating with Terahertz Frequencies in NdNiO3,"Formation of charge-density-waves in ordered electronic phases (such as
+charge-order) is an emergent phenomenon in the perovskite class of correlated
+oxides. This scenario is visualized to prevail in exotic RNiO3 (R=rare-earth)
+nickelates in which the structure controls the incipient charge-order to form
+in weak localization limit. However, any consequent effect demonstrating these
+nickelates in rare category of charge-density-waves conductors with controlled
+charge-lattice interactions has been a fundamental challenge so-far. Here, we
+present first evidence of the charge-density-waves in a prototypical NdNiO3
+system employing terahertz time-domain spectroscopy along selective crystal
+axes. A finite peak structure at 5meV in the terahertz conductivity displays
+all the characteristics of a charge-density-wave condensate. Contrasting
+charge-dynamics of collective charge-density-waves mode and Drude conductivity
+emerging, respectively, from orthorhombic and cubic symmetries disentangle
+charge-ordering from the insulating state, establish a novel structure-property
+cause-effect relationship, and present opportunities to harness these diverse
+attributes in oxide electronics.",1412.3244v1
+2014-12-14,X-ray and neutron reflectometry study of copper surface reconstruction caused by implantation of high-energy oxygen ions,"Combination of neutron and X-ray reflectometry was used to study the vertical
+structure of 100 nm-thin copper films with implanted oxygen ions of energy E =
+[10-30] keV and doses D=[0.2-5.4]x$10^{16}$ $cm^{-2}$. The study shows that
+oxygen ion implantation with an energy of E = 30 keV leads to the formation of
+a 3 nm thick layer on the surface. Density and copper/oxygen stoichiometry of
+the observed surface layer are close to $Cu_2O$ oxide. We attribute the $Cu_2O$
+oxide formation to highly mobilized copper atoms generated by stimulated ion
+implantation.",1412.4356v1
+2014-12-16,Defect chemistry in layered transition-metal oxides from screened hybrid density functional calculations,"We report a comprehensive first-principles study of the thermodynamics and
+transport of intrinsic point defects in layered oxide cathode materials
+LiMO$_2$ (M=Co, Ni), using density-functional theory and the
+Heyd-Scuseria-Ernzerhof screened hybrid functional. We find that LiCoO$_2$ has
+a complex defect chemistry; different electronic and ionic defects can exist
+under different synthesis conditions, and LiCoO$_2$ samples free of cobalt
+antisite defects can be made under Li-excess (Co-deficient) environments. A
+defect model for lithium over-stoichiometric LiCoO$_2$ is also proposed, which
+involves negatively charged lithium antisites and positively charged small
+(hole) polarons. In LiNiO$_2$, a certain amount of Ni$^{3+}$ ions undergo
+charge disproportionation and the concentration of nickel ions in the lithium
+layers is high. Tuning the synthesis conditions may reduce the nickel antisites
+but would not remove the charge disproportionation. In addition, we find that
+LiMO$_2$ cannot be doped $n$- or $p$-type; the electronic conduction occurs via
+hopping of small polarons and the ionic conduction occurs via migration of
+lithium vacancies, either through a monovacancy or divacancy mechanism,
+depending on the vacancy concentration.",1412.5064v1
+2014-12-19,Hydrogen sensing by sol-gel grown NiO and NiO:Li thin films,"Hydrogen sensors have been prepared using nickel oxide (NiO) and
+lithium-doped nickel oxide (NiO:Li) thin films, deposited on glass substrates
+by the sol-gel spin coating technique. The surface morphology, structure,
+optical and electrical properties of the obtained films were studied. Hydrogen
+sensing results are presented for three operating temperatures (140, 160, and
+180 {\deg}C) and for hydrogen concentrations ranging from 1000 to 15000 ppm in
+synthetic air. The NiO and NiO:Li (2% and 8% doping concentrations) sensors
+show maximum responses for the operating temperature of 180 {\deg}C. When
+tested at different hydrogen concentrations in air, the lithium-doped NiO
+sensors showed a higher response than the undoped NiO films.",1412.6554v1
+2014-12-22,Large anisotropic thermal conductivity of intrinsically two-dimensional metallic oxide PdCoO$_2$,"The highly conductive layered metallic oxide \pdcoo{} is a near-perfect
+analogue to an alkali metal in two dimensions. It is distinguished from other
+two-dimensional electron systems where the Fermi surface does not reach the
+Brillouin zone boundary by a high planar electron density exceeding $10^{15}$
+cm$^{-2}$. The simple single-band quasi-2D electronic structure results in
+strongly anisotropic transport properties and limits the effectiveness of
+electron-phonon scattering. Measurements on single crystals in the temperature
+range from 10-300K show that the thermal conductivity is much more weakly
+anisotropic than the electrical resistivity, as a result of significant phonon
+heat transport. The in-plane thermoelectric power is linear in temperature at
+300\,K and displays a purity-dependent peak around 50K. Given the extreme
+simplicity of the band-structure, it is possible to identify this peak with
+phonon drag driven by normal electron-phonon scattering processes.",1412.6919v1
+2014-12-22,Dimensionality Control of d-orbital Occupation in Oxide Superlattices,"Manipulating the orbital state in a strongly correlated electron system is of
+fundamental and technological importance for exploring and developing novel
+electronic phases. Here, we report an unambiguous demonstration of orbital
+occupancy control between t2g and eg multiplets in quasi-twodimensional
+transition metal oxide superlattices (SLs) composed of a Mott insulator LaCoO3
+and a band insulator LaAlO3. As the LaCoO3 sublayer thickness approaches its
+fundamental limit (i.e. one unit-cell-thick), the electronic state of the SLs
+changed from a Mott insulator, in which both t2g and eg orbitals are partially
+filled, to a band insulator by completely filling (emptying) the t2g (eg)
+orbitals. We found the reduction of dimensionality has a profound effect on the
+electronic structure evolution, which is, whereas, insensitive to the epitaxial
+strain. The remarkable orbital controllability shown here offers a promising
+pathway for novel applications such as catalysis and photovoltaics, where the
+energy of d level is an essential parameter.",1412.7139v1
+2014-12-25,Band Structure and Terahertz Optical Conductivity of Transition Metal Oxides: Theory and Application to CaRuO$_3$,"Density functional plus dynamical mean field calculations are used to show
+that in transition metal oxides, rotational and tilting (GdFeO$_3$-type)
+distortions of the ideal cubic perovskite structure produce a multiplicity of
+low-energy optical transitions which affect the conductivity down to
+frequencies of the order of $1$ or $2$~mV (terahertz regime), mimicking
+non-Fermi-liquid effects even in systems with a strictly Fermi-liquid
+self-energy. For CaRuO$_3$, a material whose measured electromagnetic response
+in the terahertz frequency regime has been interpreted as evidence for
+non-Fermi-liquid physics, the combination of these band structure effects and a
+renormalized Fermi-liquid self-energy accounts for the low frequency optical
+response which had previously been regarded as a signature of exotic physics.
+Signatures of deviations from Fermi-liquid behavior at higher frequencies
+($\sim 100$~meV) are discussed.",1412.7803v2
+2015-01-20,Formation of hydroxylamine on dust grains via ammonia oxidation,"The quest to detect prebiotic molecules in space, notably amino acids,
+requires an understanding of the chemistry involving nitrogen atoms.
+Hydroxylamine (NH$_2$OH) is considered a precursor to the amino acid glycine.
+Although not yet detected, NH$_2$OH is considered a likely target of detection
+with ALMA. We report on an experimental investigation of the formation of
+hydroxylamine on an amorphous silicate surface via the oxidation of ammonia.
+The experimental data are then fed into a simulation of the formation of
+NH$_2$OH in dense cloud conditions. On ices at 14 K and with a modest
+activation energy barrier, NH$_2$OH is found to be formed with an abundance
+that never falls below a factor 10 with respect to NH$_3$. Suggestions of
+conditions for future observations are provided.",1501.04701v1
+2015-01-27,Realization of a reversible switching in TaO2 polymorphs via Peierls distortion for resistance random access memory,"Transition-metal-oxide based resistance random access memory is a promising
+candidate for next-generation universal non-volatile memories. Searching and
+designing appropriate new materials used in the memories becomes an urgent
+task. Here, a new structure with the TaO2 formula was predicted using
+evolutionary algorithms in combination with first-principles calculations. This
+new structure having a triclinic symmetry (T-TaO2) is both energetically and
+dynamically more favorable than the commonly believed rutile structure
+(R-TaO2). Our hybrid functional calculations show that T-TaO2 is a
+semiconductor with a band gap of 1.0 eV, while R-TaO2 is a metallic conductor.
+This large difference in electrical property makes TaO2 a potential candidate
+for resistance random access memory (RRAM). Furthermore, we have shown that
+T-TaO2 is actually a Peierls distorted R-TaO2 phase and the transition between
+these two structures is via a directional displacement of Ta atoms. The energy
+barrier for the reversible phase transition from R-TaO2 to T-TaO2 is 0.19
+eV/atom and the other way around is 0.23 eV/atom, suggesting low power
+consumption for the resistance switch. The present findings provide a new
+mechanism for the resistance switch and will also stimulate experimental work
+to fabricate tantalum oxides based RRAM.",1501.06632v1
+2015-01-29,"Link between local iron coordination, Fe 2p XPS core level line shape and Mg segregation into thin magnetite films grown on MgO(001)","A well ordered Fe(001) ultra thin film epitaxially grown on MgO(001) has been
+oxidized by post deposition annealing in oxygen atmosphere. LEED patterns
+indicate the formation of magnetite (Fe$_3$O$_4$) after one hour of oxygen
+exposure. The LEED pattern remains stable despite annealing the sample for
+further four hours. In contrast X-ray Photoelectron Spectroscopy (XPS) of the
+Fe $2p$ core levels suggests the formation of an iron oxide comprising mostly
+of merely trivalent iron. This discrepancy is analyzed and discussed employing
+charge transfer multiplet calculations for the Fe $2p$ XPS spectra. We find
+that Mg ion segregation from the substrate into the magnetite thin film
+replacing octahedrally coordinated Fe$^{2+}$ ions and the excess occupation of
+octahedral sites which are unoccupied in the ideal inverse spinel structure are
+driving forces for the altered shape of the Fe $2p$ XPS spectra. Different
+potential models which might explain the nature of the Mg ion segregation into
+the magnetite films are discussed.",1501.07443v1
+2015-02-03,Structure and morphology of epitaxially grown Fe3O4/NiO bilayers on MgO(001),"Crystalline Fe3O4/NiO bilayers were grown on MgO(001) substrates using
+reactive molecular beam epitaxy to investigate their structural properties and
+their morphology. The film thickness either of the Fe3O4 film or of the NiO
+film has been varied to shed light on the relaxation of the bilayer system. The
+surface properties as studied by x-ray photo electron spectroscopy and low
+energy electron diffraction show clear evidence of stoichiometric well-ordered
+film surfaces. Based on the kinematic approach x-ray diffraction experiments
+were completely analyzed. As a result the NiO films grow pseudomorphic in the
+investigated thickness range (up to 34nm) while the Fe3O4 films relax
+continuously up to the thickness of 50nm. Although all diffraction data show
+well developed Laue fringes pointing to oxide films of very homogeneous
+thickness, the Fe3O4-NiO interface roughens continuously up to 1nm
+root-mean-square roughness with increasing NiO film thickness while the Fe3O4
+surface is very smooth independent on the Fe3O4 film thickness. Finally, the
+Fe3O4-NiO interface spacing is similar to the interlayer spacing of the oxide
+films while the NiO-MgO interface is expanded.",1502.00866v1
+2015-02-04,Persistent semi-metal-like nature of epitaxial perovskite CaIrO3 thin films,"Strong spin-orbit coupled 5d transition metal based ABO3 oxides, especially
+iridates, allow tuning parameters in the phase diagram and may demonstrate
+important functionalities, for example, by means of strain effects and
+symmetry-breaking, because of the interplay between the Coulomb interactions
+and strong spin-orbit coupling. Here, we have epitaxially stabilized high
+quality thin films of perovskite (Pv) CaIrO3. Film on the best lattice-matched
+substrate shows semi-metal-like characteristics. Intriguingly, imposing tensile
+or compressive strain on the film by altering the underlying lattice-mismatched
+substrates still maintains semi-metallicity with minute modification of the
+effective correlation as tensile (compressive) strain results in tiny increases
+(decreases) of the electronic bandwidth. In addition, magnetoresistance remains
+positive with a quadratic field dependence. This persistent semi-metal-like
+nature of Pv-CaIrO3 thin films with minute changes in the effective correlation
+by strain may provide new wisdom into strong spin-orbit coupled 5d based oxide
+physics.",1502.01261v3
+2015-02-06,Crack Formation in Ceramic Films Used in Solid Oxide Fuel Cells,"The manufacture of solid oxide fuel cells (SOFCs) involves fabrication of a
+multilayer ceramic structure, for which constrained sintering is a key
+processing step in many cases. Defects are often observed in the sintered
+structure, but their formation during sintering is not well understood. In this
+work, various ceramic films were fabricated by screen printing and a variety of
+defects observed. Some films showed mud-cracking defects, whereas others
+presented distributed large pores. Mud cracking defects were found to originate
+from a network of fine cracks present in the green film and formed during
+drying and binder burn-out. Control of these early stages is essential for
+producing crack-free films. In order to investigate how defects evolve during
+sintering, artificial cracks were introduced in the green films using
+indentation. It was observed that crack opening always increased during
+constrained sintering. In contrast, similar initial cracks could be closed and
+healed during co-sintering.",1502.01878v1
+2015-02-10,Disorder-free localization around the conduction band edge of crossing and kinked silicon nanowires,"We explore ballistic regime quantum transport characteristics of
+oxide-embedded crossing and kinked silicon nanowires (NWs) within a large-scale
+empirical pseudopotential electronic structure framework, coupled to the
+Kubo-Greenwood transport analysis. A real-space wave function study is
+undertaken and the outcomes are interpreted together with the findings of
+ballistic transport calculations. This reveals that ballistic transport edge
+lies tens to hundreds of millielectron volts above the lowest unoccupied
+molecular orbital, with a substantial number of localized states appearing in
+between, as well as above the former. We show that these localized states are
+not due to the oxide interface, but rather core silicon-derived. They manifest
+the wave nature of electrons brought to foreground by the reflections
+originating from NW junctions and bends. Hence, we show that the crossings and
+kinks of even ultraclean Si NWs possess a conduction band tail without a
+recourse to atomistic disorder.",1502.03033v1
+2015-02-11,Combined AES/Factor Analysis and RBS Investigation of a Thermally Treated Pt/Ti Metallisation on SiO2,"Pt/Ti metallisation bilayers are used as bottom electrodes for ferroelectric
+thin films. During deposition of the ferroelectric films, these electrodes are
+exposed to elevated temperatures causing modifications of the Pt/Ti bottom
+electrode. Diffusion and oxidation of the Ti adhesion layer have been studied
+by the application of factor analysis to AES depth profile data and by RBS.
+Factor analysis was employed to extract the chemical information from the
+measured AES spectra and to derive semiquantitative depth profiles of the
+identified material compounds. RBS was used to obtain the quantitative depth
+distribution of the elements. By the combination of both methods, diffusion and
+oxidation processes were observed and could be precisely describe.",1502.03413v1
+2015-02-12,"Electroluminescence from isolated defects in zinc oxide, towards electrically triggered single photon sources at room temperature","Single photon sources are required for a wide range of applications in
+quantum information science, quantum cryptography and quantum communications.
+However, so far majority of room temperature emitters are only excited
+optically, which limits their proper integration into scalable devices. In this
+work, we overcome this limitation and present room temperature electrically
+triggered light emission from localized defects in zinc oxide (ZnO)
+nanoparticles and thin films. The devices emit at the red spectral range and
+show excellent rectifying behavior. The emission is stable over an extensive
+period of time, providing an important prerequisite for practical devices. Our
+results open up possibilities to build new ZnO based quantum integrated devices
+that incorporate solid-state single photon sources for quantum information
+technologies.",1502.03735v1
+2015-02-16,Photostimulation activates restorable fragmentation of single mitochondrion by initiating oxide flashes,"Mitochondrial research is important to ageing, apoptosis, and mitochondrial
+diseases. In previous works, mitochondria are usually stimulated indirectly by
+proapoptotic drugs to study mitochondrial development, which is in lack of
+controllability, or spatial and temporal resolution. These chemicals or even
+gene techniques regulating mitochondrial dynamics may also activate other
+inter- or intra-cellular processes simultaneously. Here we demonstrate a
+photostimulation method on single-mitochondrion level by tightly-focused
+femtosecond laser that can precisely activate restorable fragmentation of
+mitochondria which soon recover their original tubular structure after tens of
+seconds. In this process, series of mitochondrial reactive oxygen species
+(mROS) flashes are observed and found very critical to mitochondrial
+fragmentation. Meanwhile, transient openings of mitochondrial permeability
+transition pores (mPTP), suggested by oscillations of mitochondrial membrane
+potential, contribute to the scavenging of redundant mROS and recovery of
+fragmented mitochondria. Those results demonstrate photostimulation as an
+active, precise and controllable method for the study of mitochondrial
+oxidative and morphological dynamics or related fields.",1502.04591v2
+2015-02-20,Giant switchable Rashba effect in oxide heterostructures,"One of the most fundamental phenomena and a reminder of the electron's
+relativistic nature is the Rashba spin splitting for broken inversion symmetry.
+Usually this splitting is a tiny relativistic correction, hardly discernible in
+experiment. Interfacing a ferroelectric, BaTiO$_3$, and a heavy 5$d$ metal with
+a large spin-orbit coupling, Ba(Os,Ir)O$_3$, we show that giant Rashba spin
+splittings are indeed possible and even fully controllable by an external
+electric field. Based on density functional theory and a microscopic tight
+binding understanding, we conclude that the electric field is amplified and
+stored as a ferroelectric Ti-O distortion which, through the network of oxygen
+octahedra, also induces a large Os-O distortion. The BaTiO$_3$/BaOsO$_3$
+heterostructure is hence the ideal test station for studying the fundamentals
+of the Rashba effect. It allows intriguing application such as the Datta-Das
+transistor to operate at room temperature.",1502.05870v1
+2015-02-23,Creation of high mobility two-dimensional electron gases via strain induced polarization at an otherwise nonpolar complex oxide interface,"The discovery of two-dimensional electron gases (2DEGs) in SrTiO3-based
+heterostructures provides new opportunities for nanoelectronics. Herein, we
+create a new type of oxide 2DEG by the epitaxial-strain-induced polarization at
+an otherwise nonpolar perovskite-type interface of CaZrO3/SrTiO3. Remarkably,
+this heterointerface is atomically sharp, and exhibits a high electron mobility
+exceeding 60,000 cm2V-1s-1 at low temperatures. The 2DEG carrier density
+exhibits a critical dependence on the film thickness, in good agreement with
+the polarization induced 2DEG scheme.",1502.06364v1
+2015-02-25,Prediction of new thermodynamically stable aluminum oxides,"Recently, it has been shown that under pressure, unexpected and
+counterintuitive chemical compounds become stable. Laser shock experiments (A.
+Rode, unpublished) on alumina (Al2O3) have shown non-equilibrium decomposition
+of alumina with the formation of free Al and a mysterious transparent phase.
+Inspired by these observations, with have explored the possibility of the
+formation of new chemical compounds in the system Al-O. Using the
+variable-composition structure prediction algorithm USPEX, in addition to the
+well-known Al2O3, we have found two extraordinary compounds Al4O7 and AlO2 to
+be thermodynamically stable in the pressure range 330-443 GPa and above 332
+GPa, respectively. Both of these compounds at the same time contain oxide O2-
+and peroxide O22- ions, and both are insulating. Peroxo-groups are responsible
+for gap states, which significantly reduce the electronic band gap of both
+Al4O7 and AlO2.",1502.07012v1
+2015-02-25,"Biophotons, coherence and photocount statistics: a critical review","Biological samples continuously emit ultra-weak photon emission (UPE, or
+""biophotons"") which stems from electronic excited states generated chemically
+during oxidative metabolism and stress. Thus, UPE can potentially serve as a
+method for non-invasive diagnostics of oxidative processes or, if discovered,
+also of other processes capable of electron excitation. While the fundamental
+generating mechanisms of UPE are fairly elucidated together with their
+approximate ranges of intensities and spectra, statistical properties of UPE is
+still a highly challenging topic. Here we review claims about nontrivial
+statistical properties of UPE, such as coherence and squeezed states of light.
+After introduction to the necessary theory, we categorize the experimental
+works of all authors to those with solid, conventional interpretation and those
+with unconventional and even speculative interpretation. The conclusion of our
+review is twofold; while the phenomenon of UPE from biological systems can be
+considered experimentally well established, no reliable evidence for the
+coherence or nonclassicality of UPE was actually achieved up to now.
+Furthermore, we propose perspective avenues in the research of statistical
+properties of biological UPE.",1502.07316v1
+2015-03-10,A Universal Channel Model for Molecular Communication Systems with Metal-Oxide Detectors,"In this paper, we propose an end-to-end channel model for molecular
+communication systems with metal-oxide sensors. In particular, we focus on the
+recently developed table top molecular communication platform. The system is
+separated into two parts: the propagation and the sensor detection. There is
+derived, based on this, a more realistic end-to-end channel model. However,
+since some of the coefficients in the derived models are unknown, we collect a
+great deal of experimental data to estimate these coefficients and evaluate how
+they change with respect to the different system parameters. Finally, a noise
+model is derived for the system to complete an end-to-end system model for the
+tabletop platform.",1503.02809v1
+2015-03-12,Indium Tin Oxide film characterization using the classical Hall effect,"We have used the classical Hall effect to electrically characterize Indium
+Tin Oxide (ITO) films grown by two different techniques on silica substrates.
+ITO films have the unique property that they can be both electrically
+conducting (and to be used for a gate electrode for example) as well as
+optically transparent (at least in the visible part of the spectrum). In the
+near infrared (NIR) the transmission typically reduces. However, the light
+absorption can in principle be compensated by growing thinner films.",1503.03679v1
+2015-03-12,"Watt-level, all-fiber, ultrafast Er/Yb-codoped double-clad fiber laser mode-locked by reduced graphene oxide interacting with a weak evanescent field","We propose a Watt-level, all-fiber, ultrafast Er/Yb-codoped double-clad fiber
+laser passively mode-locked by reduced graphene oxide (rGO) interacting with a
+weak evanescent field of photonic crystal fiber (PCF). The rGO solution is
+filled into the cladding holes of the PCF based on total reflection, and after
+evaporation, the rGO flakes bear only 1/107 of the total energy in laser
+system, which enhances the thermal damage threshold and decreases the
+accumulated nonlinearity. By incorporating the saturable absorber into an
+Er/Yb-codoped fiber ring cavity, stable conventional soliton with a duration of
+573 fs is generated, and a average output power up to 1.14 W is obtained.",1503.03748v1
+2015-03-18,Observation of high angular momentum excitons in cuprous oxide,"The recent observation of dipole-allowed $P$-excitons up to principal quantum
+numbers of $n=25$ in cuprous oxide has given insight into exciton states with
+unprecedented spectral resolution. While so far the exciton description as a
+hydrogen-like complex has been sufficient for cubic crystals, we demonstrate
+here distinct deviations: The breaking of rotational symmetry leads to mixing
+of high angular momentum $F$- and $H$-excitons with the $P$-excitons so that
+they can be observed in absorption. The $F$-excitons show a three-fold
+splitting that depends systematically on $n$, in agreement with theoretical
+considerations. From detailed comparison of experiment and theory we determine
+the cubic anisotropy parameter of the Cu$_2$O valence band.",1503.05517v1
+2015-03-27,Quantum dot nonlinearity through cavity-enhanced feedback with a charge memory,"In an oxide apertured quantum dot (QD) micropillar cavity-QED system, we
+found strong QD hysteresis effects and lineshape modifications even at very low
+intensities corresponding to less than 0.001 intracavity photons. We attribute
+this to the excitation of charges by the intracavity field; charges that get
+trapped at the oxide aperture, where they screen the internal electric field
+and blueshift the QD transition. This in turn strongly modulates light
+absorption by cavity QED effects, eventually leading to the observed hysteresis
+and lineshape modifications. The cavity also enables us to observe the QD
+dynamics in real time, and all experimental data agrees well with a power-law
+charging model. This effect can serve as a novel tuning mechanism for quantum
+dots.",1503.08142v1
+2015-04-08,Giant Oscillating Thermopower at Oxide Interfaces,"Understanding the nature of charge carriers at the LaAlO3/SrTiO3 interface is
+one of the major open issues in the full comprehension of the charge
+confinement phenomenon in oxide heterostructures. Here, we investigate
+thermopower to study the electronic structure in LaAlO3/SrTiO3 at low
+temperature as a function of gate field. In particular, under large negative
+gate voltage, corresponding to the strongly depleted charge density regime,
+thermopower displays record-high negative values of the order of 10^4 - 10^5
+microV/K, oscillating at regular intervals as a function of the gate voltage.
+The huge thermopower magnitude can be attributed to the phonon-drag
+contribution, while the oscillations map the progressive depletion and the
+Fermi level descent across a dense array of localized states lying at the
+bottom of the Ti 3d conduction band. This study is the first direct evidence of
+a localized Anderson tail in the two-dimensional (2D) electron liquid at the
+LaAlO3/SrTiO3 interface.",1504.01901v1
+2015-04-17,Temporal and Dose Kinetics of Tunnel Relaxation of Non-Equilibrium Near-Interfacial Charged Defects in Insulators,"This paper is devoted mainly to mathematical aspects of modeling and
+simulation of tunnel relaxation of nonequilibrium charged oxide traps located
+at/near the interface insulator - conductive channel, for instance in
+irradiated MOS devices. The generic form of the tunnel annealing response
+function was derived from the rate equation for the charged defect buildup and
+annealing as a linear superposition of the responses of different defects with
+different time constants. Using this linear response function, a number of
+important practical problems are analyzed and discussed. Combined tunnel and
+thermal or RICN annealing, power-like temporal relaxation after a single ion
+strike into the gate oxide, are described in context of general approach.",1504.04525v1
+2015-05-07,Suppression of excess oxygen for environmentally stable amorphous In-Si-O thin-film transistors,"We discuss the environmental instability of amorphous indium oxide
+(InOx)-based thin-film transistors (TFTs) in terms of the excess oxygen in the
+semiconductor films. A comparison between amorphous InOx doped with low and
+high concentrations of oxygen binder (SiO2) showed that out-diffusion of oxygen
+molecules causes drastic changes in the film conductivity and TFT turn-on
+voltages. Incorporation of sufficient SiO2 could suppress fluctuations in
+excess oxygen because of the high oxygen bond-dissociation energy and low Gibbs
+free energy. Consequently, the TFT operation became rather stable. The results
+would be useful for the design of reliable oxide TFTs with stable electrical
+properties.",1505.01628v1
+2015-05-19,Flexible Sensory Platform Based on an Electrolyte-Gated Oxide Neuron Transistor,"Inspired by the dendritic integration and spiking operation of a biological
+neuron, flexible oxide-based neuron transistors gated by solid-state
+electrolyte films are fabricated on flexible plastic substrates for biochemical
+sensing applications. When a quasi-static dual-gate laterally synergic sensing
+mode is adopted, the neuron transistor sensor shows a high pH sensitivity of
+~105 mV/pH, which is higher than the Nernst limit. Our results demonstrate that
+single-spike dynamic mode can remarkably improve the pH sensitivity, reduce
+response/recover time and power consumption. We also find that appropriate
+depression applied on the sensing gate electrode can further enhance the pH
+sensitivity and reduce the power consumption. Our flexible neuron transistors
+provide a new-concept sensory platform for biochemical detection with high
+sensitivity, rapid response and ultralow power consumption.",1505.04964v1
+2015-05-26,Functionalized graphene as a model system for the two-dimensional metal-insulator transition,"Reports of metallic behavior in two-dimensional (2D) systems such as high
+mobility metal-oxide field effect transistors, insulating oxide interfaces,
+graphene, and MoS2 have challenged the well-known prediction of Abrahams, et
+al. that all 2D systems must be insulating. The existence of a metallic state
+for such a wide range of 2D systems thus reveals a wide gap in our
+understanding of 2D transport that has become more important as research in 2D
+systems expands. A key to understanding the 2D metallic state is the
+metal-insulator transition (MIT). In this report, we demonstrate the existence
+of a disorder induced MIT in functionalized graphene, a model 2D system.
+Magneto-transport measurements show that weak-localization overwhelmingly
+drives the transition, in contradiction to theoretical assumptions that
+enhanced electron-electron interactions dominate. These results provide the
+first detailed picture of the nature of the transition from the metallic to
+insulating states of a 2D system.",1505.07053v1
+2015-05-29,An in- and ex-situ TEM study into the oxidisation of titanium (IV) sulphide,"The degradation of liquid dispersed titanium (IV) sulphide (TiS$_2$) is
+studied from the point of view of oxidisation. TiS$_2$ is a layered
+two-dimensional nanomaterial, with potential for energy storage applications.
+However, flakes in dispersion were observed to degrade. We examined two
+oxidisation routes: deionised water at room temperature and oxygen gas within
+the temperature range 150-350{\deg}C. Water was seen to slowly oxidise flakes
+inwards from the edge, forming an amorphous oxide, a result comparable to the
+state of flakes which degraded within the original dispersion. Oxygen gas was
+seen to rapidly oxidise entire flakes to a polycrystalline oxide, when heated
+275 {\deg}C and above. Degradation was studied with scanning transmission
+electron microscopy (STEM), energy dispersed x-ray spectroscopy (EDX) and
+electron energy-loss spectroscopy (EELS). Density Functional Theory
+calculations have shown oxidisation by both water and gas molecules to be
+thermodynamically favourable.",1505.08074v1
+2015-06-01,Lattice correlation of Hubbard excitons in a Mott insulator Sr2IrO4 and reconstruction of their hopping dynamics via time-dependent coherence analysis of the Bragg diffraction,"In correlated oxides the coupling of quasiparticles to other degrees of
+freedom such as spin and lattice plays critical roles in the emergence of
+symmetry-breaking quantum ordered states such as high temperature
+superconductivity. We report a strong lattice coupling of photon induced
+Hubbard excitonic quasiparticles in spin-orbital coupling Mott insulator
+Sr2IrO4. Combining time-resolved optical spectroscopy techniques, we further
+reconstructed spatiotemporal map of the diffusion of quasiparticles via
+time-dependent coherence analysis of the x-ray Bragg diffraction peak. Due to
+the unique electronic configuration of the exciton, the strong lattice
+correlation is unexpected but extends the similarity between Sr2IrO4 and
+cuprates under highly non-equilibrium conditions. The coherence analysis method
+we developed may have important implications for characterizing the structure
+and carrier dynamics in a wider group of oxide heterostructures.",1506.00630v1
+2015-06-11,Surface diffusion control of the photocatalytic oxidation in air/TiO2 heterogeneous reactors,"The diffusion of superoxide radical anions on the surface of TiO2 catalysts
+is theoretically considered as an important step in the kinetics of
+photocatalytic oxidation of toxic pollutants. A detailed analysis is performed
+to discriminate the effects of rotation, anion and adsorption bonds vibrations
+on the diffusion coefficient. A resonant dependence of the diffusivity on the
+lattice parameters of the TiO2 surface is discovered showing that the most
+rapid diffusion takes place when the lattice parameters are twice larger than
+the bond length of the superoxide radical anions. Whereas the rotation and
+vibrations normal to the catalyst surface are important, the anion bond
+vibrations do not affect the diffusivity due to their low amplitudes as
+compared to the lattice parameters.",1506.03581v2
+2015-06-15,Phase separation from electron confinement at oxide interfaces,"Oxide heterostructures are of great interest both for fundamental and
+applicative reasons. In particular the two-dimensional electron gas at the
+LaAlO$_3$/SrTiO$_3$ or LaTiO$_3$/SrTiO$_3$ interfaces displays many different
+physical properties and functionalities. However there are clear indications
+that the interface electronic state is strongly inhomogeneous and therefore it
+is crucially relevant to investigate possible intrinsic electronic mechanisms
+underlying this inhomogeneity. Here the electrostatic potential confining the
+electron gas at the interface is calculated self-consistently, finding that the
+electron confinement at the interface may induce phase separation, to avoid a
+thermodynamically unstable state with a negative compressibility. This provides
+a generic robust and intrinsic mechanism for the experimentally observed
+inhomogeneous character of these interfaces.",1506.04777v1
+2015-06-28,"Nitrogen oxides under pressure stability, ionization, polymerization, and superconductivity","Nitrogen oxides are textbook class of molecular compounds, with extensive
+industrial applications. Nitrogen and oxygen are also among the most abundant
+elements in the universe. We explore the N-O system at 0 K and up to 500 GPa
+though ab initio evolutionary simulations. Results show that two phase
+transformations of stable molecular NO2 exist at 7 and 64 GPa, and followed by
+decomposition of NO2 at 91 GPa. All of the NO+NO3- structures are found to be
+metastable at T=0 K, so experimentally reported ionic NO+NO3- is either
+metastable or stabilized by temperature. Upon increasing pressure, N2O5
+transforms from P-1 to C2/c structure at 51 GPa. NO becomes thermodynamically
+stable at 198 GPa. This polymeric phase is superconducting (Tc = 2.0 K) and
+contains a -N-N- backbone.",1506.08362v1
+2015-06-29,New class of planar ferroelectric Mott insulators via first principles design,"Inorganic perovskite oxide ferroelectrics have recently generated substantial
+interest for photovoltaic applications; however, existing materials suffer from
+excessive electronic band gaps and insufficient electric polarization. The
+recent resurgence of hybrid perovskite ferroelectrics addresses the
+aforementioned deficiencies, but they are highly unstable against environmental
+effects and an inorganic resolution may still be optimal. Here we use
+first-principles calculations to design a low band gap, planar ferroelectric by
+leveraging the complexity of layered double perovskite oxides AA$^\prime
+$BB$^\prime$O$_6$. We exploit A$\ne$A$^\prime$ size mismatch, a nominally empty
+$d$-shell on the B-site, and A cations bearing lone-pair electrons to achieve a
+large ferroelectric polarization. Additionally, B$^\prime\ne$B is chosen to
+achieve full charge transfer and a Mott susceptible filling on the
+B$^\prime$-site, yielding a low band gap. These principles are illustrated in
+BaBiCuVO$_6$, BaBiNiVO$_6$, BaLaCuVO$_6$, and PbLaCuVO$_6$, which could be
+realized in layer-by-layer growth. This new class of materials could lead to
+stable, high-efficiency photovoltaic.",1506.08855v1
+2015-07-06,Implementing odd-axions in dimensional oxidation of non-geometric type IIB action,"In a setup of type IIB superstring compactification on an orientifold of a
+${\mathbb T}^6/{\mathbb Z}_4$ sixfold, the presence of geometric flux
+($\omega$) and non-geometric fluxes ($Q, R$) is implemented along with the
+standard NS-NS and RR three-form fluxes ($H, F$). After computing the F/D-term
+contributions to the ${\cal N}=1$ four dimensional effective scalar potential,
+we rearrange the same into `suitable' pieces by using a set of new generalized
+flux orbits. Subsequently, we dimensionally oxidize the various pieces of the
+total four dimensional scalar potential to guess their ten-dimensional origin.",1507.01612v3
+2015-07-18,Addressing the Challenges of Using Ferromagnetic Electrodes in the Molecular Spintronics Devices,"Ferromagnetic electrodes chemically bonded with thiol functionalized
+molecules can produce novel molecular spintronics devices. However, major
+challenges lie in developing Ferromagnetic electrodes based commercially viable
+device fabrication scheme that consider the susceptibility of ferromagnetic
+electrodes to oxidation, chemical etching, and stress induced deformations
+during fabrication and usage. This paper studies NiFe, an alloy used in the
+present day memory devices and high-temperature engineering applications, as a
+candidate FM electrode for the fabrication of MSDs. Our spectroscopic
+reflectance studies show that NiFe start oxidizing aggressively beyond 90 C.
+The NiFe surfaces, aged for several months or heated for several minutes below
+90 C, exhibited remarkable electrochemical activity and were suitable for
+chemical bonding with the thiol functionalized molecular device elements. NiFe
+also demonstrated excellent etching resistance and minimized the mechanical
+stress induced deformities. This paper demonstrates the successful utilization
+of NiFe electrodes in the tunnel junction based molecular device fabrication
+approach. This paper is expected to fill the knowledge gap impeding the
+experimental development of ferromagnetic electrode based molecular spintronics
+devices for realizing novel logic and memory devices and observing a numerous
+theoretically predicted phenomenon.",1507.05146v1
+2015-07-21,Compensation for TID Damage in SOI Pixel Devices,"We are investigating adaption of SOI pixel devices for future high energy
+physic(HEP) experiments. The pixel sensors are required to be operational in
+very severe radiation environment. Most challenging issue in the adoption is
+the TID (total ionizing dose) damage where holes trapped in oxide layers affect
+the operation of nearby transistors. We have introduced a second SOI layer -
+SOI2 beneath the BOX (Buried OXide) layer - in order to compensate for the TID
+effect by applying a negative voltage to this electrode to cancel the effect
+caused by accumulated positive holes. In this paper, the TID effects caused by
+Co gamma-ray irradiation are presented based on the transistor characteristics
+measurements. The irradiation was carried out in various biasing conditions to
+investigate hole accumulation dependence on the potential configurations. We
+also compare the data with samples irradiated with X-ray. Since we observed a
+fair agreement between the two irradiation datasets, the TID effects have been
+investigated in a wide dose range from 100~Gy to 2~MGy.",1507.05860v1
+2015-07-25,Chemical Bondings Induced Rich Electronic Properties of Oxygen Absorbed Few-layer Graphenes,"Electronic properties of graphene oxides enriched by the strong chemical
+bondings are investigated using first-principle calculations. They are very
+sensitive to the changes in the number of graphene layer, stacking
+configuration, and distribution of oxygen. The feature-rich electronic
+structures exhibit the destruction or distortion of Dirac cone, opening of band
+gap, anisotropic energy dispersions, O- and (C,O)-dominated energy dispersions,
+and extra critical points. All the few-layer graphene oxides are semi-metals
+except for the semiconducting monolayer ones. For the former, the distorted
+Dirac-cone structures and the O-dominated energy bands near the Fermi level are
+revealed simultaneously. The orbital-projected density of states (DOS) have
+many special structures mainly coming from a composite energy band, the
+parabolic and partially flat ones. The DOS and spatial charge distributions
+clearly indicate the critical bondings in O-O, C-O and C-C bonds, being
+responsible for the diversified properties.",1507.07057v1
+2015-07-26,New ground states of fluorinated and oxidized phosphorene: structural and electronic properties,"We systematically explore chemical functionalization of monolayer black
+phosphorene via chemisorption of oxygen and fluorine atoms. Using the cluster
+expansion technique, with vary- ing concentration of the adsorbate, we
+determine the ground states considering both single- as well as double- side
+chemisorption, which have novel chemical and electronic properties. The nature
+of the bandgap depends on the concentration of the adsorbate: for fluorination
+the direct bandgap first decreases, and then increases while becoming indirect,
+with increasing fluorination, while for oxidation the bandgap first increases
+and then decreases, while mostly maintaining its direct nature. Further we find
+that the unique anisotropic free-carrier effective mass for both the electrons
+and holes, can be changed and even rotated by 90 degrees, with controlled
+chemisorption, which can be useful for exploring unusual quantum Hall effect,
+and novel electronic devices based on phosphorene.",1507.07230v3
+2015-08-07,Interplay between O defects and SiC stacking at the SiC/SiO$_2$ interface,"We investigate the effect of SiC stacking on the 4H-SiC/SiO$_2$ interface,
+both in the presence and absence of O defects, which appear during thermal
+oxidation, via first principles calculations. It is known that 4H-SiC(0001) has
+two different surface types, depending on which of the two lattice sites, $h$
+or $k$, is at the surface [K. Arima \textit{et al}., Appl. Phys. Lett.
+\textbf{90}, 202106 (2007)]. We find interlayer states along the conduction
+band edge of SiC, whose location changes depending on the interface type, and
+thus too the effect of defects. When $h$ sites are directly at the interface, O
+defects remove interfacial conduction band edge states. On the other hand, when
+$k$ sites are at the interface, the conduction band edge is insensitive to the
+presence of O defects. These differences will impact on the operation of SiC
+devices because the most commonly used SiC based metal-oxide-semiconductor
+field-effect transistors rely on the electronic structure of the conduction
+band.",1508.01590v1
+2015-08-11,Multilayer Layer Graphene Nanoribbon Flash Memory: Analysis of Programming and Erasing Operation,"Flash memory based on floating gate transistor is the most widely used memory
+technology in modern microelectronic applications. We recently proposed a new
+concept of multilayer graphene nanoribbon (MLGNR) and carbon nanotube (CNT)
+based floating gate transistor design for future nanoscale flash memory
+technology. In this paper, we analyze the tunneling current mechanism in the
+proposed graphene-CNT floating gate transistor. We anticipate that the proposed
+floating gate transistor would adopt Fowler-Nordheim (FN) tunneling during its
+programming and erase operations. In this paper, we have investigated the
+mechanism of tunneling current and the factors that would influence this
+current and the behavior of the proposed floating gate transistor. The analysis
+reveals that FN tunneling is a strong function of the high field induced by the
+control gate, and the thicknesses of the control oxide and the tunnel oxide.",1508.02590v1
+2015-08-19,Electric field control of spin lifetimes in Nb-SrTiO$_3$ by spin-orbit fields,"We show electric field control of the spin accumulation at the interface of
+the oxide semiconductor Nb-SrTiO$_{3}$ with Co/AlO$_{x}$ spin injection
+contacts at room temperature. The in-plane spin lifetime $\tau_\parallel$ as
+well as the ratio of the out-of-plane to in-plane spin lifetime
+$\tau_\perp/\tau_\parallel$ is manipulated by the built-in electric field at
+the semiconductor surface, without any additional gate contact. The origin of
+this manipulation is attributed to Rashba Spin-Orbit Fields (SOFs) at the
+Nb-SrTiO$_3$ surface and shown to be consistent with theoretical model
+calculations based on SOF spin flip scattering. Additionally, the junction can
+be set in a high or low resistance state, leading to a non-volatile control of
+$\tau_\perp/\tau_\parallel$, consistent with the manipulation of the Rashba SOF
+strength. Such room temperature electric field control over the spin state is
+essential for developing energy-efficient spintronic devices and shows promise
+for complex oxide based (spin)electronics",1508.04649v1
+2015-08-29,Degradation of Phosphorene in Air: Understanding at Atomic Level,"Phosphorene is a promising two dimensional (2D) material with a direct band
+gap, high carrier mobility, and anisotropic electronic properties.
+Phosphorene-based electronic devices, however, are found to degrade upon
+exposure to air. In this paper, we provide an atomic level understanding of
+stability of phosphorene in terms of its interaction with O2 and H2O. The
+results based on density functional theory together with first principles
+molecular dynamics calculations show that O2 could spontaneously dissociate on
+phosphorene at room temperature. H2O will not strongly interact with pristine
+phosphorene, however, an exothermic reaction could occur if phosphorene is
+first oxidized. The pathway of oxidation first followed by exothermic reaction
+with water is the most likely route for the chemical degradation of the
+phosphorene-based devices in air.",1508.07461v2
+2015-09-15,Non-linear photochemical pathways in laser induced atmospheric aerosol formation,"We measured the chemical composition and the size distribution of aerosols
+generated by femtosecond-Terawatt laser pulses in the atmosphere using an
+aerosol mass spectrometer (AMS). We show that nitric acid condenses in the form
+of ammonium nitrate, and that oxidized volatile organics also contribute to
+particle growth. These two components account for two thirds and one third,
+respectively, of the dry laser-condensed mass. They appear in two different
+modes centred at 380 nm and 150 nm. The number concentration of particles
+between 25 and 300 nm increases by a factor of 15. Pre-existing water droplets
+strongly increase the oxidative properties of the laser-activated atmosphere,
+substantially enhancing the condensation of organics under laser illumination.",1509.04600v1
+2015-09-23,Ferroelectric thermal phase transition and polarization precursor dynamics in CaxBa1-xNb2O6(CBN) tungsten bronze type oxides,"Polycrystals of CaxBa1-xNb2O6(CBN) tungsten bronze type oxides have been
+prepared and their structural, dielectric, and thermal properties have been
+investigated. It was found that CBN alloys with ferroelectric tetragonal
+tungsten bronze structure were only available in a composition range of 0.19 <=
+x <= 0.32. It was also showed that CBN can be classified as a ferroelectric
+with a first-order thermal phase transition showing polarization precursor
+dynamics before transition into the ferroelectric phase, in sharp contrast to
+an isostructural alloy SrxBa1-xNb2O6(SBN) that shows typical relaxor behaviors.
+The local polarizations were found to grow exponentially within the
+paraelectric mother phase in a large temperature range of Tc<T<Tc+ 88~140 K on
+cooling. Furthermore, a phase diagram was established for CBN ferroelectric
+alloys. These findings may get an insight into the true nature of ferroelectric
+phase transition in this potential electro-optic material.",1509.06852v1
+2015-09-24,First observation of temperature dependent lightinduced response of Ge25As10Se65 thin films,"Ge rich ternary chalcogenide glasses (ChG) exhibit photobleaching (PB) when
+illuminated with bandgap light and such an effect is originating from the
+combined effect of intrinsic structural changes and photo-oxidation. In a sharp
+contradict to these previous observations, in this letter, we demonstrate for
+the first time that Ge rich Ge25As10Se65 ChG thin films exhibit photodarkening
+(PD) at 20 K and PB at 300 and 420 K for continuous illumination of ~ 3 hours.
+Strikingly, the temporal evolution of PD/PB show distinct characteristics at
+the temperatures of illumination and provide valuable information on the light
+induced structural changes. Further, structure specific far infrared (FIR)
+absorption measurements give direct evidence of different structural units
+involved in PD/PB at the contrasting temperatures. By comparing the
+lightinduced effects in vacuum and air, we conclude that intrinsic structural
+changes dominate over photo-oxidation in the observed PB in Ge25As10Se65 ChG
+thin films.",1509.07412v1
+2015-10-07,Layer-by-Layer Dielectric Breakdown of Hexagonal Boron Nitride,"Hexagonal boron nitride (BN) is widely used as a substrate and gate insulator
+for two-dimensional (2D) electronic devices. The studies on insulating
+properties and electrical reliability of BN itself, however, are quite limited.
+Here, we report a systematic investigation of the dielectric breakdown
+characteristics of BN using conductive atomic force microscopy. The electric
+field strength was found to be ~12 MV/cm, which is comparable to that of
+conventional SiO2 oxides because of the covalent bonding nature of BN. After
+the hard dielectric breakdown, the BN fractured like a flower into equilateral
+triangle fragments. However, when the applied voltage was terminated precisely
+in the middle of the dielectric breakdown, the formation of a hole that did not
+penetrate to the bottom metal electrode was clearly observed. Subsequent I-V
+measurements of the hole indicated that the BN layer remaining in the hole was
+still electrically inactive. Based on these observations, layer-by-layer
+breakdown was confirmed for BN with regard to both physical fracture and
+electrical breakdown. Moreover, statistical analysis of the breakdown voltages
+using a Weibull plot suggested the anisotropic formation of defects. These
+results are unique to layered materials and unlike the behavior observed for
+conventional 3D amorphous oxides.",1510.01930v1
+2015-10-16,Thermodynamics of the Oxygen Evolution Electrocatalysis in Metal-Organic Frameworks,"Metal-organic frameworks (MOFs) provide a versatile and tailorable material
+platform that embody many desirable attributes for photocatalytic
+water-splitting. The approach taken in this study was to use Density Functional
+Theory (DFT) to predict the thermodynamic energy barriers of the oxygen
+evolution reaction (OER) for three MOF functionalizations. A Zr-MIL-125 MOF
+design was selected for this study that incorporates three linker designs, a
+1,4-benzenedicarboxylate (BDC), BDC functionalized with an amino group
+(BDC+NH2), and BDC functionalized with nitro group (BDC+NO2). The study found
+several key differences between homogeneous planar catalyst thermodynamics and
+MOF based thermodynamics, the most significant being the non-unique or
+heterogeneity of reaction sites. Additionally, the funcationalization of the
+MOF was found to significantly influence the hydroperoxyl binding energy, which
+proves to be the largest hurdle for both oxide and MOF based catalyst. Both of
+these findings provide evidance that many of the limitations precluding planar
+homogeneous catalysts can be surpassed with a MOF based catalyst. While none of
+the MOF designs selected for this study out-performed state-of-the-art oxide
+based catalysts, the BDC+NH2 proved to be the best with a predicted
+over-potential for spontaneous OER evolution to be 3.03eV.",1510.04851v1
+2015-10-30,Design of Mott and topological phases on buckled 3d-oxide honeycomb lattices,"Perovskite bilayers with (111)-orientation combine a honeycomb lattice as a
+key feature with the strongly correlated, multiorbital nature of electrons in
+transition metal oxides. In a systematic DFT+$U$ study of (111)-oriented
+(La$X$O$_3$)$_2$/(LaAlO$_3$)$_4$ superlattices, we establish trends in the
+evolution of ground states versus band filling in (111)-oriented
+(La$X$O$_3$)$_2$/(LaAlO$_3$)$_4$ superlattices, with $X$ spanning the entire
+$3d$ transition metal series. The competition between local quasi-cubic and
+global triangular symmetry triggers unanticipated broken symmetry phases, with
+mechanisms ranging from Jahn-Teller distortions, to charge-, spin-, and
+orbital-ordering. LaMnO$_3$, where spin-orbit coupling opens a sizable gap in
+the Dirac-point Fermi surface, emerges as a topological Chern insulator.",1510.09177v1
+2015-11-01,Ab initio GW plus cumulant calculation for isolated band system: Application to organic conductor (TMTSF)2PF6 and transition-metal oxide SrVO3,"We present ab initio GW plus cumulant-expansion calculations for an organic
+compound (TMTSF)2PF6 and a transition-metal oxide SrVO3. These materials
+exhibit characteristic low-energy band structures around the Fermi level, which
+bring about interesting low-energy properties; the low-energy bands near the
+Fermi level are isolated from the other bands and, in the isolated bands,
+unusually low-energy plasmon excitations occur. To study the effect of this
+low-energy-plasmon fluctuation on the electronic structure, we calculate
+spectral functions and photoemission spectra using the ab initio cumulant
+expansion of the Green's function based on the GW self-energy. We found that
+the low-energy plasmon fluctuation leads to an appreciable renormalization of
+the low-energy bands and a transfer of the spectral weight into the incoherent
+part, thus resulting in an agreement with experimental photoemission data.",1511.00218v1
+2015-11-02,On the modeling and simulation of reaction-transfer dynamics in semiconductor-electrolyte solar cells,"The mathematical modeling and numerical simulation of
+semiconductor-electrolyte systems play important roles in the design of
+high-performance semiconductor-liquid junction solar cells. In this work, we
+propose a macroscopic mathematical model, a system of nonlinear partial
+differential equations, for the complete description of charge transfer
+dynamics in such systems. The model consists of a
+reaction-drift-diffusion-Poisson system that models the transport of electrons
+and holes in the semiconductor region and an equivalent system that describes
+the transport of reductants and oxidants, as well as other charged species, in
+the electrolyte region. The coupling between the semiconductor and the
+electrolyte is modeled through a set of interfacial reaction and current
+balance conditions. We present some numerical simulations to illustrate the
+quantitative behavior of the semiconductor-electrolyte system in both dark and
+illuminated environments. We show numerically that one can replace the
+electrolyte region in the system with a Schottky contact only when the bulk
+reductant-oxidant pair density is extremely high. Otherwise, such replacement
+gives significantly inaccurate description of the real dynamics of the
+semiconductor-electrolyte system.",1511.00417v1
+2015-11-16,Detection of the adsorption of water monolayers through the ion oscillation frequency in the magnesium oxide lattice by means of Low Energy Electron Diffraction,"We investigate the variation of the oscillation frequency of the Mg$^{2+}$
+and O$^{2-}$ ions in the magnesium oxide lattice due to the interactions of the
+surface with water monolayers by means of Low Energy Electron Diffraction. Our
+key result is a new technique to determine the adsorbate vibrations produced by
+the water monolayers on the surface lattice as a consequence of their change in
+the surface Debye temperature and its chemical shift. The latter was
+systematically investigated for different annealing times and for a constant
+external thermal perturbation in the range of 110-300 K in order to accomplish
+adsorption or desorption of water monolayers in the surface lattice.",1511.05074v1
+2015-11-17,Deviations of the exciton level spectrum in cuprous oxide from the hydrogen series,"Recent high-resolution absorption spectroscopy on excited excitons in cuprous
+oxide [Nature (London) 514, 343 (2014)] has revealed significant deviations of
+their spectrum from that of the ideal hydrogen-like series. Here we show that
+the complex band dispersion of the crystal, which determines the kinetic energy
+of electrons and holes, strongly affects the exciton binding energy.
+Specifically, we show that the nonparabolicity of the band dispersion is the
+main cause of the deviation from the hydrogen series. Experimental data
+collected from high-resolution absorption spectroscopy in electric fields
+validate the assignment of the deviation to the nonparabolicity of the band
+dispersion.",1511.05458v2
+2015-11-19,Symmetry-driven atomic rearrangement at a brownmillerite-perovskite interface,"Many of the recent advancements in oxide heterostructures have been
+attributed to modification of spin, charge, lattice, and orbital order
+parameters at atomically well-defined interfaces. However, the details on the
+structural, chemical, and electrostatic evolution of interfaces comprised of
+materials with different crystallographic symmetries remain to be understood.
+In this work, we have mapped out the interfacial connectivity of atoms of two
+dissimilar materials, the perovskite SrTiO3 and the brownmillerite SrCoO2.5,
+using high resolution scanning transmission electron microscopy and geometric
+phase analysis. We observed unique symmetry-mismatch driven atomic
+displacements restricted to only the first few atomic layers, which can
+critically modify the properties of the system. Provided that SrCoO2.5 is a
+promising energy material due to its open framework structure, the improved
+understanding of the interfacial structure on the atomic level can lead to the
+rational design of novel oxide heterostructures.",1511.06405v1
+2015-11-24,Field Effect Transistors with Sub-Micrometer Gate Lengths Fabricated from LaAlO$_3$-SrTiO$_3$-Based Heterostructures,"The possible existence of short-channel effects in oxide field-effect
+transistors is investigated by exploring field-effect transistors with various
+gate lengths fabricated from LaAlO$_3$-SrTiO$_3$ heterostructures. The studies
+reveal the existence of channel-length modulation and drain-induced barrier
+lowering for gate lengths below 1 {\mu}m, with a characteristic behavior
+comparable to semiconducting devices. With the fabrication of field-effect
+transistors with gate lengths as small as 60 nm the results demonstrate the
+possibility to fabricate by electron-beam lithography functional devices based
+on complex oxides with characteristic lengths of several ten nanometers.",1511.07680v1
+2016-01-20,In-vacuum scattered light reduction with cupric oxide surfaces for sensitive fluorescence detection,"We demonstrate a simple and easy method for producing low-reflectivity
+surfaces that are ultra-high vacuum compatible, may be baked to high
+temperatures, and are easily applied even on complex surface geometries. Black
+cupric oxide (CuO) surfaces are chemically grown in minutes on any copper
+surface, allowing for low-cost, rapid prototyping and production. The
+reflective properties are measured to be comparable to commercially available
+products for creating optically black surfaces. We describe a vacuum apparatus
+which uses multiple blackened copper surfaces for sensitive, low-background
+detection of molecules using laser-induced fluorescence.",1601.05308v1
+2016-02-03,Direct Observation of Localized Radial Oxygen Migration in Functioning Tantalum Oxide Memristors,"Oxygen migration in tantalum oxide, a promising next-generation storage
+material, is studied using in-operando x-ray absorption spectromicroscopy and
+is used to microphysically describe accelerated evolution of conduction channel
+and device failure. The resulting ring-like patterns of oxygen concentration
+are modeled using thermophoretic forces and Fick diffusion, establishing the
+critical role of temperature-activated oxygen migration that has been under
+question lately.",1602.01204v2
+2016-02-02,Linewidths in excitonic absorption spectra of cuprous oxide,"We present a theoretical calculation of the absorption spectrum of cuprous
+oxide $\left(\mathrm{Cu_{2}O}\right)$ based on the general theory developed by
+Y. Toyozawa. An inclusion not only of acoustic phonons but also of optical
+phonons and of specific properties of the excitons in $\mathrm{Cu_{2}O}$ like
+the central-cell corrections for the $1S$-exciton allows us to calculate the
+experimentally observed line widths in experiments by T. Kazimierczuk et al
+[Nature 514, 343, (2014)] within the same order of magnitude, which
+demonstrates a clear improvement in comparison to earlier work on this topic.
+We also discuss a variety of further effects, which explain the still
+observable discrepancy between theory and experiment but can hardly be included
+in theoretical calculations.",1602.01813v1
+2016-02-11,Enhanced bifunctional oxygen catalysis in strained LaNiO3 perovskites,"Strain is known to greatly influence low temperature oxygen electrocatalysis
+on noble metal films, leading to significant enhancements in bifunctional
+activity essential for fuel cells and metal-air batteries. However, its
+catalytic impact on transition metal oxide thin films, such as perovskites, is
+not widely understood. Here, we epitaxially strain the conducting perovskite
+LaNiO3 to systematically determine its influence on both the oxygen reduction
+and oxygen evolution reaction. Uniquely, we found that compressive strain could
+significantly enhance both reactions, yielding a bifunctional catalyst that
+surpasses the performance of noble metals such as Pt. We attribute the improved
+bifunctionality to strain-induced splitting of the eg orbitals, which can
+customize orbital asymmetry at the surface. Analogous to strain-induced shifts
+in the d-band center of noble metals relative to Fermi level, such splitting
+can dramatically affect catalytic activity in this perovskite and other
+potentially more active oxides.",1602.03858v1
+2016-02-12,Nanopatterning process based on epitaxial masking for the fabrication of electronic and spintronic devices made of La0.67Sr0.33MnO3/LaAlO3/SrTiO3 heterostructures with in situ interfaces,"The fabrication of oxide electronics devices is presently hindered by the
+lack of standardized and well established patterning procedures, applicable
+down to the nanoscale. In this work, the authors propose a procedure to obtain
+patterns with resolution around 100 nm on (La,Sr)MnO3/LaAlO3/SrTiO3
+heterostructures. Our method is based on a multistep technique, which includes
+wet and dry etching, epitaxial masking, and e-beam lithography. Our procedure
+is devised to define independent patterns on the interfacial two dimensional
+electron gas and on the metallic top electrode, while preserving an all-in situ
+approach for the heterostructure growth. The authors show results on nano-scale
+devices based on (La,Sr)MnO3/LaAlO3/SrTiO3, suitable for oxide spintronics
+applications.",1602.04108v1
+2016-02-18,"Uniting Superhydrophobic, Superoleophobic and Lubricating Fluid Infused Slippery Behavior on Copper Oxide Nano-structured Substrates","Copper oxide nanostructures with spherical (0D), needle (1D) and hierarchical
+cauliflower (3D) morphologies are used to demonstrate superhydrophobic,
+superoleophobic and slippery behavior. These nanostructures are synthesized on
+galvanized steel substrates using a simple chemical bath deposition method by
+tuning precursor concentration. Subsequent coating of low surface energy
+polymer, polydimethylsiloxane, results in superhydrophobicity with water
+contact angle ~160(2){\deg} and critical sliding angle ~2{\deg}. When
+functionalized with low-surface energy perfluoroalkyl silane, these surfaces
+display high repellency for low surface tension oils and hydrocarbons. Among
+them, the hierarchical cauliflower morphology exhibits better re-entrant
+structure thus show the best superoleophobicity with 149{\deg} contact angle
+for dodecane having surface tension 25.3 mNm-1. If these nanostructured
+substrates are infused with lubricant Silicone oil, they show excellent
+slippery behavior for water drops. Due to the lubricating nature of Silicone
+oil, the Silicone oil infused slippery surfaces (SOIS) show low contact angle
+hysteresis (~2{\deg}) and critical tilt angle (~2{\deg}). The hierarchical
+cauliflower nanostrcuture exhibit better slippery characteristics and stability
+compared to the other nanostructured surfaces.",1602.05813v1
+2016-02-24,"Mechanisms for p-type behavior of ZnO, Zn$_{1-x}$Mg$_x$O and related oxide semiconductors","Possibilities of turning intrinsically n-type oxide semiconductors like ZnO
+and Zn$_{1-x}$Mg$_x$O into p-type materials are investigated. Motivated by
+recent experiments on Zn$_{1-x}$Mg$_x$O doped with nitrogen we analyze the
+electronic defect levels of point defects N$_{{\rm O}}$, v$_{{\rm Zn}}$, and
+N$_{{\rm O}}$-v$_{{\rm Zn}}$ pairs in ZnO and Zn$_{1-x}$Mg$_x$O by means of
+self-interaction-corrected density functional theory calculations. We show how
+the interplay of defects can lead to shallow acceptor defect levels, although
+the levels of individual point defects N$_{{\rm O}}$ are too deep in the band
+gap for being responsible for p-type conduction. We relate our results to
+p-type conduction paths at grain boundaries seen in polycrystalline ZnO and
+develop an understanding of a p-type mechanism which is common to ZnO,
+Zn$_{1-x}$Mg$_x$O, and related materials.",1602.07451v2
+2016-02-24,Transport in strongly-coupled graphene-LaAlO3/SrTiO3 hybrid systems,"We report on the transport properties of hybrid devices obtained by
+depositing graphene on a LaAlO3/SrTiO3 oxide junction hosting a 4 nm-deep
+two-dimensional electron system. At low graphene-oxide inter-layer bias the two
+electron systems are electrically isolated, despite their small spatial
+separation, and very efficient reciprocal gating is shown. A pronounced
+rectifying behavior is observed for larger bias values and ascribed to the
+interplay between electrostatic depletion and tunneling across the LaAlO3
+barrier. The relevance of these results in the context of strongly-coupled
+bilayer systems is discussed.",1602.07506v1
+2016-02-29,"Easily doped p-type, low hole effective mass, transparent oxides","Fulfillment of the promise of transparent electronics has been hindered until
+now largely by the lack of semiconductors that can be doped p-type in a stable
+way, and that at the same time present high hole mobility and are highly
+transparent in the visible spectrum. Here, a high-throughput study based on
+first-principles methods reveals four oxides, namely X2SeO2, with X = La, Pr,
+Nd, and Gd, which are unique in that they exhibit excellent characteristics for
+transparent electronic device applications-i.e., a direct band gap larger than
+3.1 eV, an average hole effective mass below the electron rest mass, and good
+p-type dopability. Furthermore, for La2SeO2 it is explicitly shown that Na
+impurities substituting La are shallow acceptors in moderate to strong
+anion-rich growth conditions, with low formation energy, and that they will not
+be compensated by anion vacancies VO or VSe.",1602.08945v1
+2016-03-02,Correlation effects on electron-phonon coupling in semiconductors: many-body theory along thermal lines,"A method is proposed for the inclusion of electron correlation in the
+calculation of the temperature dependence of band structures arising from
+electron-phonon coupling. It relies on an efficient exploration of the
+vibrational phase space along the recently introduced thermal lines. Using the
+$G_0W_0$ approximation, the temperature dependence of the direct gaps of
+diamond, silicon, lithium fluoride, magnesium oxide, and titanium dioxide is
+calculated. Within the proposed formalism, a single calculation at each
+temperature of interest is sufficient to obtain results of the same accuracy as
+in alternative, more expensive methods. It is shown that many-body
+contributions beyond semi-local density functional theory modify the
+electron-phonon coupling strength by almost $50$% in diamond, silicon, and
+titanium dioxide, but by less than $5$% in lithium flouride and magnesium
+oxide. The results reveal a complex picture regarding the validity of
+semi-local functionals for the description of electron-phonon coupling.",1603.00551v1
+2016-03-07,Prediction of a Two-dimensional Phosphorus Nitride Monolayer,"Today, 2D semiconductor materials have been extended into the nitrogen group:
+phosphorene, arsenene, antimonene and even nitrogene. Motivated by them, based
+upon first-principles density functional calculations, we propose a new
+two-dimensional phosphorus nitride (PN) structure that is stable well above the
+room temperature, due to its extremely high cohesive energy. Unlike
+phosphorene, PN structure is resistant to high temperature oxidation. The
+structure is predicted to be a semiconductor with a wide, indirect band gap of
+2.64 eV. More interestingly, the phosphorus nitride monolayer experiences an
+indirect-to-direct band-gap transition at a relatively small tensile strain.
+Such dramatic transformation in the electronic structure combined with
+structural stability and oxidation resistance at high temperature could pave
+the way for exciting innovations in high-speed ultrathin transistors, power
+electronic modules, ultra-high efficiency LEDs and semiconductor lasers.",1603.01957v2
+2016-03-09,Oxygen vacancies: The origin of n-type conductivity in ZnO,"Oxygen vacancy (VO) is a common native point defects that plays crucial roles
+in determining the physical and chemical properties of metal oxides such as
+ZnO. However, fundamental understanding of VO is still very sparse.
+Specifically, whether VO is mainly responsible for the n-type conductivity in
+ZnO has been still unsettled in the past fifty years. Here we report on a study
+of oxygen self-diffusion by conceiving and growing oxygen-isotope ZnO
+heterostructures with delicately-controlled chemical potential and Fermi level.
+The diffusion process is found to be predominantly mediated by VO. We further
+demonstrate that, in contrast to the general belief of their neutral attribute,
+the oxygen vacancies in ZnO are actually +2 charged and thus responsible for
+the unintentional n-type conductivity as well as the non-stoichiometry of ZnO.
+The methodology can be extended to study oxygen-related point defects and their
+energetics in other technologically important oxide materials.",1603.02831v2
+2016-03-09,Novel chemistry of lithium oxides and superconducting low-pressure LiO4,"We study the stability of Li-O compounds as a function of pressure, with Li
+ion battery applications and fundamental chemical interest in mind. Using the
+ab initio evolutionary algorithm, we predict stability of novel compounds LiO4,
+Li5O3 and Li6O under pressure. LiO4, formed at the pressure of just 6 GPa, can
+be seen as {\epsilon}-O8 accepting two electrons from two Li atoms. This phase
+is superconducting, with Tc up to 12.2 K at 10 GPa. This is remarkable, because
+elemental oxygen becomes superconducting at much higher pressure (96 GPa) and
+has much lower Tc (<0.6 K), and suggests that chemical alloying with other
+elements has the potential of not only decreasing metallization pressure, but
+also of increasing Tc. Since {\epsilon}-O8 is called red oxygen, LiO4 can be
+identified ""lithium red-oxid"", and is distinct from superoxide. Additionally,
+Li5O3 is stable at pressures above 70 GPa and can be represented as a hybrid
+structure 4Li2O {\cdot} Li2O2, and electride suboxide Li6O is stable above 62
+GPa.",1603.02880v1
+2016-03-13,A sub-1-volt analog metal oxide memristive-based synaptic device for energy-efficient spike-based computing systems,"Nanoscale metal oxide memristors have potential in the development of
+brain-inspired computing systems that are scalable and efficient1-3. In such
+systems, memristors represent the native electronic analogues of the biological
+synapses. However, the characteristics of the existing memristors do not fully
+support the key requirements of synaptic connections: high density, adjustable
+weight, and low energy operation. Here we show a bilayer memristor that is
+forming-free, low-voltage (~|0.8V|), energy-efficient (full On/Off switching at
+~2pJ), and reliable. Furthermore, pulse measurements reveal the analog nature
+of the memristive device, that is it can be directly programmed to intermediate
+resistance states. Leveraging this finding, we demonstrate
+spike-timing-dependent plasticity (STDP), a spike-based Hebbian learning rule4.
+In those experiments, the memristor exhibits a marked change in the normalized
+synaptic strength (>30 times) when the pre- and post-synaptic neural spikes
+overlap. This demonstration is an important step towards the physical
+construction of high density and high connectivity neural networks.",1603.03979v1
+2016-03-14,Spin Hall Effect Induced Spin Transfer Through an Insulator,"When charge current passes through a normal metal that exhibits spin Hall
+effect, spin accumulates at the edge of the sample in the transverse direction.
+We predict that this spin accumulation, or spin voltage, enables quantum
+tunneling of spin through an insulator or vacuum to reach a ferromagnet without
+transferring charge. In a normal metal/insulator/ferromagnetic insulator
+trilayer (such as Pt/oxide/YIG), the quantum tunneling explains the
+spin-transfer torque and spin pumping that exponentially decay with the
+thickness of the insulator. In a normal metal/insulator/ferromagnetic metal
+trilayer (such as Pt/oxide/Co), the spin transfer in general does not decay
+monotonically with the thickness of the insulator. Combining with the spin Hall
+magnetoresistance, this tunneling mechanism points to the possibility of a new
+type of tunneling spectroscopy that can probe the magnon density of states of a
+ferromagnetic insulator in an all-electrical and noninvasive manner.",1603.04240v2
+2016-03-28,Liquid-Gated High Mobility and Quantum Oscillation of the Two-Dimensional Electron Gas at an Oxide Interface,"Electric field effect in electronic double layer transistor (EDLT)
+configuration with ionic liquids as the dielectric materials is a powerful
+means of exploring various properties in different materials. Here we
+demonstrate the modulation of electrical transport properties and extremely
+high mobility of two-dimensional electron gas at LaAlO$_3$/SrTiO$_3$ (LAO/STO)
+interface through ionic liquid-assisted electric field effect. By changing the
+gate voltages, the depletion of charge carrier and the resultant enhancement of
+electron mobility up to 19380 cm$^2$/Vs are realized, leading to quantum
+oscillations of the conductivity at the LAO/STO interface. The present results
+suggest that high-mobility oxide interfaces which exhibit quantum phenomena
+could be obtained by ionic liquid-assisted field effect.",1603.08471v1
+2016-04-14,Vacancies and oxidation of 2D group-IV monochalcogenides,"Point defects in the binary group-IV monochalcogenide monolayers of SnS,
+SnSe, GeS, GeSe are investigated using density-functional-theory calculations.
+Several stable configurations are found for oxygen defects, however we give
+evidence that these materials are less prone to oxidation than phosphorene,
+with which monochalcogenides are isoelectronic and share the same orthorhombic
+structure. Concurrent oxygen defects are expected to be vacancies and
+substitutional oxygen. We show that it is energetically favorable oxygen be
+incorporated into the layers substituting for a chalcogen (O S/Se defects), and
+different from most of the other defects investigated, this defect preserves
+the electronic structure of the material. Thus, we suggest that annealing
+treatments can be useful for the treatment of functional materials where loss
+mechanisms due to the presence of defects are undesirable.",1604.04092v1
+2016-04-22,Thermoelectric Properties of Antiperovskite Calcium Oxides Ca3PbO and Ca3SnO,"We report the thermoelectric properties of polycrystalline samples of
+Ca3Pb1-xBixO (x = 0, 0.1, 0.2) and Ca3SnO, both crystallizing in a cubic
+antiperovskite-type structure. The Ca3SnO sample shows metallic resistivity and
+its thermoelectric power approaches 100 uV K-1 at room temperature, resulting
+in the thermoelectric power factor of Ca3SnO being larger than that of
+Ca3Pb1-xBixO. On the basis of Hall and Sommerfeld coefficients, the Ca3SnO
+sample is found to be a p-type metal with a carrier density of ~1019 cm-3, a
+mobility of ~80 cm2 V-1 s-1, both comparable to those in degenerated
+semiconductors, and a moderately large hole carrier effective mass. The
+coexistence of moderately high mobility and large effective mass observed in
+Ca3SnO, as well as possible emergence of a mutivalley electronic structure with
+a small band gap at low-symmetry points in k-space, suggests that the
+antiperovskite Ca oxides have strong potential as a thermoelectric material.",1604.06541v2
+2016-04-25,Quasiparticle interference on cubic perovskite oxide surfaces,"We report the first observation of coherent surface states on cubic
+perovskite oxide SrVO3(001) thin films through spectroscopic imaging scanning
+tunneling microscopy. A direct link between the observed atomic-scale
+interference patterns and the formation of a dxy-derived surface state is
+supported by first-principles calculations. Furthermore, we show that the
+apical oxygens on the topmost VO2 plane play a critical role in controlling the
+spectral weight of the observed coherent surface state.",1604.07334v2
+2016-05-22,Hybrid Multi-Walled Carbon Nanotube TiO2 Electrode Material for Next Generation Energy Storage Devices,"Current supercapacitors present several distinct limitations that severely
+inhibit the efficiency, power, and electrical capacitance of energy storage
+devices. Supercapacitors present an exciting prospect that has countless
+applications in renewable energy storage and modern day electronic devices. In
+recent years the exciting development of carbon nanotubes (CNTs) has presented
+an advantage in electrode development. CNTs, however beneficial for their
+increased electrode surface area, have severe limitations regarding
+conductivity and electrode density. Creating a nanocomposite hybrid out of a
+transition metal-oxide and carbon nanotube array would help the current
+limitations of the modern supercapacitor. TiO2 was chosen for its common
+occurrence in everyday materials and promising capacitance levels. A
+multi-walled carbon nanotube array was grown on a SiO2 precursor via CCVD. The
+transition metal oxide was then deposited via RF Sputtering methods to a MWCNT
+array. Recharge tests and characterization were conducted using scanning
+capacitance microscopy (SCM). While these tests are preliminary, this novel
+hybrid electrode represents an exciting prospect for the future of the
+efficiency of electrochemical energy storage as well as an advance towards a
+future of providing inexpensive energy storage solutions around the world.",1606.00820v1
+2016-06-14,Drastic changes of electronic structure and crystal chemistry upon oxidation of SnII2TiO4E2 into SnIV2TiO6: an ab initio study,"From DFT based calculations establishing energy-volume equations of state and
+electron localization mapping, the electronic structure and crystal chemistry
+changes from Sn2TiO4 to Sn2TiO6 by oxidation are rationalized; the key effect
+being the destabilization of divalent tin SnII towards tetravalent state SnIV
+leading to rutile Sn2TiO6 as experimentally observed. The subsequent electronic
+structure change is highlighted in the relative change of the electronic band
+gap which increases from ~1eV up to 2.2 eV and the 1.5 times increase of the
+bulk modulus assigned to the change from covalently SnII based compound to the
+more ionic SnIV one. Such trends are also confronted with the relevant
+properties of black SnIIO characterized by very small band gap.",1606.04201v1
+2016-06-23,Rashba-Dresselhaus spin-splitting in the bulk ferroelectric oxide BiAlO$_3$,"It has been recently suggested that the coexistence of ferroelectricity and
+Rashba-like spin-splitting effects due to spin-orbit coupling in a single
+material may allow for a non-volatile electric control of spin degrees of
+freedom. In the present work, we compared the structural and ferroelectric
+properties of tetragonal and rhombohedral phases of ferroelectric BiAlO$_3$ by
+means of density-functional calculations. In both phases, we carefully
+investigated Rashba and Dresselhaus effects, giving rise to spin-splitting in
+their bulk electronic structure, particularly near the conduction band minimum,
+supplementing our first-principles results with an effective $ k\cdot p$ model
+analysis. The full reversal of the spin texture with ferroelectric polarization
+switching was also predicted. BiAlO$_3$ can therefore be considered as the
+first known oxide to exhibit a coexistence of ferroelectricity and
+Rashba-Dresselhaus effects.",1606.07400v2
+2016-06-30,Dynamic defect correlations dominate activated electronic transport in SrTiO3,"Strontium titanate (SrTiO3, STO) is a critically important material for the
+study of emergent electronic phases in complex oxides, as well as for the
+development of applications based on their heterostructures. Despite the large
+body of knowledge on STO, there are still many uncertainties regarding the role
+of defects in the properties of STO, including their influence on
+ferroelectricity in bulk STO and ferromagnetism in STO-based heterostructures.
+We present a detailed analysis of the decay of persistent photoconductivity in
+STO single crystals with defect concentrations that are relatively low but
+significantly affect their electronic properties. The results show that
+photo-activated electron transport cannot be described by a superposition of
+the properties due to independent point defects as current models suggest but
+is, instead, governed by defect complexes that interact through dynamic
+correlations. These results emphasize the importance of defect correlations for
+activated electronic transport properties of semiconducting and insulating
+perovskite oxides.",1606.09475v1
+2016-07-07,Understanding and controlling the work function of perovskite oxides using Density Functional Theory,"Perovskite oxides containing transition metals are promising materials in a
+wide range of electronic and electrochemical applications. However, neither
+their work function values nor an understanding of their work function physics
+have been established. Here, we predict the work function trends of a series of
+perovskite ($ABO_3$ formula) materials using Density Functional Theory, and
+show that the work functions of (001)-terminated AO- and $BO_2$-oriented
+surfaces can be described using concepts of electronic band filling, bond
+hybridization, and surface dipoles. The calculated range of AO ($BO_2$) work
+functions are 1.60-3.57 eV (2.99-6.87 eV). We find an approximately linear
+correlation ($R^2$ between 0.77-0.86, depending on surface termination) between
+work function and position of the oxygen 2p band center, which correlation
+enables both understanding and rapid prediction of work function trends.
+Furthermore, we identify $SrVO_3$ as a stable, low work function, highly
+conductive material. Undoped (Ba-doped) $SrVO_3$ has an intrinsically low
+AO-terminated work function of 1.86 eV (1.07 eV). These properties make
+$SrVO_3$ a promising candidate material for a new electron emission cathode for
+application in high power microwave devices, and as a potential electron
+emissive material for thermionic energy conversion technologies.",1607.02121v1
+2016-07-27,The humidity sensing properties and mechanism of strontium-hexaferrite ceramics,"The humidity sensitivity of n-type strontium-hexaferrite semiconductors,
+X-type (Sr2Co2Fe28O46) and Z-type (Sr3Co2Fe24O41), are investigated at room
+temperature. The contact and reactions between water and material surface are
+demonstrated considering the formation of oxide ion vacancy, singly-ionized /
+fully-ionized oxide ion vacancy, and the chemisorbed / physisorbed / condensed
+water. An impedance spectra model is proposed considering the
+material-electrode interface, interior material, grain boundary, absorbed water
+and Warburg response. The mechanism of electronic coupled with protonic
+conduction and humidity sensing mechanism are explained.",1607.07929v2
+2016-09-06,From Filter Paper to Functional Actuator by Poly(ionic liquid)-Modified Graphene Oxide,"A commercially available membrane filter paper composed of mixed cellulose
+esters bearing typically an interconnected pore structure was transformed into
+a stimuli-responsive bilayer actuator by depositing a thin film of poly(ionic
+liquid)-modified graphene oxide sheets (GO-PIL) onto the filter paper. In
+acetone vapor, the as-synthesized bilayer actuator bent readily into multiple
+loops at a fast speed with the GO-PIL top film inwards. Upon pulling back into
+air the actuator recovered their original shape. The asymmetric swelling of the
+top GO-PIL film and the bottom porous filter paper towards organic vapor offers
+a favorably synergetic function to drive the actuation. The PIL polymer chains
+in the hybrid film were proven crucial to enhance the adhesion strength between
+the GO sheets and the adjacent filter paper to avoid interfacial delamination
+and thus improve force transfer. The overall construction allows a prolonged
+lifetime of the bilayer actuator under constant operation, especially when
+compared to that of the GO/filter paper bilayer actuator without PIL.",1609.01390v1
+2016-09-12,Sequential pulsed laser deposition of homoepitaxial SrTiO$_3$ thin films,"Control of thin film stoichiometry is of primary relevance to achieve desired
+functionality. Pulsed laser deposition ablating from binary-oxide targets
+(sequential deposition) can be applied to precisely control the film
+composition, offsetting the importance of growth conditions on the film
+stoichiometry. In this work, we demonstrate that the cation stoichiometry of
+SrTiO$_3$ thin films can be finely tuned by sequential deposition from SrO and
+TiO$_2$ targets. Homoepitaxial SrTiO$_3$ films were deposited at different
+substrate temperatures and Ti/Sr pulse ratios, allowing the establishment of a
+growth window for stoichiometric SrTiO$_3$. The growth kinetics and nucleation
+processes were studied by reflection high-energy electron diffraction and
+atomic force microscopy, providing information about the growth mode and the
+degree of off-stoichiometry. At the optimal (stoichiometric) growth conditions,
+films exhibit atomically flat surfaces, whereas off-stoichiometry is
+accommodated by crystal defects, 3D islands and/or surface precipitates
+depending on the substrate temperature and the excess cation. This technique
+opens the way to precisely control stoichiometry and doping of oxide thin
+films.",1609.03318v1
+2016-09-12,Orthorhombic boron oxide under pressure: in situ study by X-ray diffraction and Raman scattering,"High-pressure phase of boron oxide, orthorhombic \b{eta}-B2O3, has been
+studied in situ by synchrotron X-ray diffraction to 22 GPa and Raman scattering
+to 46 GPa at room temperature. The bulk modulus of \b{eta}-B2O3 has been found
+to be 169(3) GPa that is in good agreement with our ab initio calculations.
+Raman and IR spectra of \b{eta}-B2O3 have been measured at ambient pressure,
+all experimentally observed bands have been attributed to the theoretically
+calculated ones, and the mode assignment has been performed. Based on the data
+on Raman shift as a function of pressure, combined with equation-of-state data,
+the Gr\""uneisen parameters of all experimentally observed Raman bands have been
+calculated. \b{eta}-B2O3 enriched by 10B isotope has been synthesized, and the
+effect of boron isotopic substitution on Raman spectra has been studied.",1609.03422v1
+2016-09-20,"Effect of strain, thickness, and local surface environment on electron transport properties of oxygen-terminated copper thin films","Electron transport is studied in surface oxidized single-crystal copper thin
+films with a thickness of up to 5.6 nm by applying density functional theory
+and density functional tight binding methods to determine electron transport
+properties within the ballistic regime. The variation of the electron
+transmission as a function of film thickness as well as the different
+contributions to the overall electron transmission as a function of depth into
+the the films is examined. Transmission at the oxidized copper film surfaces is
+found to be universally low. Films with thickness greater than 2.7 nm exhibit a
+similar behavior in local transmission per unit area with depth from the film
+surface; transmission per unit area initially increases rapidly and then
+plateaus at a depth of approximately 0.35-0.5 nm away from the surface,
+dependent on surface facet. Unstrained films tend to exhibit a higher
+transmission per unit area than corresponding films under tensile strain.",1609.06150v2
+2016-09-23,The mechanism of spin-orbit coupling in a 2D oxide interface,"The presence of spin-orbit coupling drives the anomalous magnetotransport at
+oxide interfaces and forms the basis for numerous intriguing properties of
+these 2D electron systems, such as topologically protected phases or
+anti-localization. For many of those systems, the identification of the
+underlying coupling mechanism is obfuscated by multi-band effects. We therefore
+analyze the transport of LaAlO$_3$/SrTiO$_3$ interfaces under high pressures, a
+technique to single out the multi-band contributions. We argue that the
+observed magnetoresistance is due to quantum interference and not related to
+Coulomb interaction. Therefore, this system is an excellent candidate to
+generate a metal-insulator transition of the long-sought symplectic 2D
+universality class. It is shown that the spin-orbit coupling can be linked
+unambiguously to the band structure with a cubic (Dresselhaus-like) rather than
+a linear (Rashba-like) spin-orbit band splitting.",1609.07425v1
+2016-10-01,"Ab initio model of amorphous zinc oxide (a-ZnO) and a-X_0.375 Z_0.625 O (X=Al, Ga and In)","Density functional theory (DFT) calculations are carried out to study the
+structure and electronic structure of amorphous zinc oxide (a-ZnO). The models
+were prepared by the ""melt-quench"" method. The models are chemically ordered
+with some coordination defects. The effect of trivalent dopants in the
+structure and electronic properties of a-ZnO is investigated. Models of
+a-X_0.375 Z_0.625 O (X=Al, Ga and In) were also prepared by the ""melt- quench""
+method. The trivalent dopants reduce the four-fold Zn and O, thereby
+introducing some coordination defects in the network. The dopants prefer to
+bond with O atom. The network topology is discussed in detail. Dopants reduce
+the gap in EDOS by producing defect states minimum while maintaining the
+extended nature of the conduction band edge.",1610.00156v1
+2016-10-07,Spin-orbit coupling controlled $J=3/2$ electronic ground state in 5$d^{3}$ oxides,"Entanglement of spin and orbital degrees of freedom drives the formation of
+novel quantum and topological physical states. Discovering new spin-orbit
+entangled ground states and emergent phases of matter requires both
+experimentally probing the relevant energy scales and applying suitable
+theoretical models. Here we report resonant inelastic x-ray scattering
+measurements of the transition metal oxides Ca$_3$LiOsO$_6$ and Ba$_2$YOsO$_6$.
+We invoke an intermediate coupling approach that incorporates both spin-orbit
+coupling and electron-electron interactions on an even footing and reveal the
+ground state of $5d^3$ based compounds, which has remained elusive in
+previously applied models, is a novel spin-orbit entangled J=3/2 electronic
+ground state. This work reveals the hidden diversity of spin-orbit controlled
+ground states in 5d systems and introduces a new arena in the search for
+spin-orbit controlled phases of matter.",1610.02375v1
+2016-10-13,Topological Phase Transition Coupled with Spin-Valley Physics in Ferroelectric Oxide Heterostructures,"The possibility to engineer the coupling of spin and valley physics is
+explored in ferroelectric oxide heterostructures with eg electronic
+configuration. We show that the polar structural distortion induces the
+appearance of spin-valley coupled properties, at the same time being
+responsible for a topological transition from a quantum spin-Hall insulating
+phase to a trivial band insulator. The coupled spin-valley physics is affected
+by the topological band inversion in a non-trivial way; while the
+valley-dependent spin polarization of both conduction and valence bands is
+preserved, a change of the Berry curvature and of spin-valley selection rules
+is predicted, leading to different circular dichroic response as well as valley
+and spin Hall effects.",1610.03982v1
+2016-10-17,Photocatalytic H2 generation using dewetted Pt-decorated TiO2 nanotubes - Optimized dewetting and oxide crystallization by a multiple annealing process,"In the present work we use TiO2 nanotube arrays, carrying a Pt coating that
+is optimally dewetted, as a photocatalyst to generate H2. In order to achieve a
+maximum H2-generation efficiency, on the one hand an ideal thermal dewetting of
+the Pt layer into nanoparticles is needed that requires an oxygen free heat
+treatment, and on the other hand an optimal crystallization of the TiO2
+nanotubes into anatase with reduced defect density is achieved only by
+annealing in O2 containing environment. To overcome this issue, we combine
+adequate reducing and oxidizing conditions in a multiple annealing treatment,
+and obtain Pt-decorated anatase TiO2 nanotubes showing significantly enhanced
+photocatalytic H2 generation ability.",1610.05208v1
+2016-10-27,Metal Insulator transition in tin doped indium oxide (ITO) thin films Quantum Correction to the electrical Conductivity,"Tin doped indium oxide (ITO) thin films are being used extensively as
+transparent conductors in several applications. In the present communication,
+we report the electrical transport in DC magnetron sputtered ITO thin films in
+low temperatures (25-300 K). The low temperature Hall effect and resistivity
+measurements reveal that the ITO thin films are moderately dis-ordered (kfl~1)
+and degenerate semiconductor. The transport of charge carriers in these
+disordered ITO thin films takes place via the de-localized states. The disorder
+effects lead to the well- known metal-insulator transition; this transition is
+observed at 110 K in ITO thin films. The metal-insulator behaviour is explained
+by the quantum correction to the conductivity (QCC); this approach is based on
+the quantum-mechanical interference effects in the disordered systems. The
+insulating behaviour is attributed to the combined effect of the weak
+localization and the electron-electron interactions.",1610.08799v1
+2016-10-27,"High efficiency, hybrid electrochromic device on polycarbonate substrates with neon sputtered WO3-x thin films","Electrochromic materials change color reversibly by applying an external DC
+voltage. One among the many emerging application of electro-chromics is the
+smart windows. The coloration efficiency, the optical colour modulation and the
+cyclability are the factors that bench mark the device. Tungsten oxide (WO3-x)
+is versatile material and reactive DC magnetron sputtering (with argon as
+sputter gas) technique is common for electro-chromics. In the present
+communication we have prepared tungsten oxide thin films by reactive DC
+magnetron sputtering technique (at room temperature 300 K) using Neon as the
+sputter gas. The thickness of the WO3 thin films are varied from 190 nm to 712
+nm. These WO3 thin films are subjected for electrochemical measurements with
+three electrode electrochemical cell in presence of 1M HCl, 1M Li2SO4 aqueous
+electrolyte and we have prepared a solid state electrochromic device with
+nafion thin film. The highest coloration efficiency of the neon sputtered WO3
+is observed as 187.9 cm2/C by lithium intercalation.",1610.08825v2
+2016-10-28,Experimental and theoretical study of metal combustion in oxygen flows,"The effects of oxygen flow speed and pressure on the iron and mild steel
+combustion are investigated experimentally and theoretically. The studied
+specimens are vertical cylindrical rods subjected to an axial oxygen flow and
+ignited at the upper end by laser irradiation. Three main stages of the
+combustion process have been identified experimentally: (1) Induction period,
+during which the rod is heated until an intensive metal oxidation begins at its
+upper end; (2) Static combustion, during which a laminar liquid ""cap"" slowly
+grows on the upper rod end; and, after the liquid cap detachment from the
+sample, (3) Dynamic combustion, which is characterized by a rapid metal
+consumption and turbulent liquid motions. An analytical description of these
+stages is given. In particular, a model of the dynamic combustion is
+constructed based on the turbulent oxygen transport through the liquid
+metal-oxide flow. This model yields a simple expression for the fraction of
+metal burned in the process, and allows one to calculate the normal propagation
+speed of the solid metal--liquid interface as a function of the oxygen flow
+speed and pressure. A comparison of the theory with the experimental results is
+made.",1610.09126v2
+2017-02-13,Ultra-low Thermal Conductivity of Nanogranular Indium Tin Oxide Films Deposited by Spray Pyrolysis,"The authors have shown that nanogranular indium tin oxide (ITO) films,
+deposited by spray pyrolysis on silicon substrate, demonstrate ultralow thermal
+conductivity ~ 0.84 +/-0.12 Wm-1K-1 at room temperature. This value is
+approximately by one order of magnitude lower than that in bulk ITO. The strong
+drop of thermal conductivity is explained by nanogranular structure and
+porosity of ITO films, resulting in enhanced phonon scattering on grain
+boundaries. The experimental results were interpreted theoretically, employing
+Boltzmann transport equation approach for phonon transport and filtering model
+for electronic transport. The calculated values of thermal conductivity are in
+a reasonable agreement with the experimental findings. The presented results
+show that ITO films with optimal nanogranular structure may be prospective for
+thermoelectric applications.",1702.03842v1
+2017-02-14,Metal-Insulator Transition and Jeff = 1/2 Spin-Orbit Insulating State in Rutile-based IrO2/TiO2 Superlattices,"By combining 5d transition-metal oxides showing pronounced spin-orbit
+interactions and oxide-based heterostructures, we propose rutile-based
+IrO2/TiO2 superlattices as promising candidates for unconventional electronic
+properties. By means of density-functional-theory simulations complemented with
+Hubbard-like corrections, we focus on the evolution of the electronic structure
+as a function of the IrO2 layer thickness and predict the heterostructures to
+exhibit a thickness-controlled metal-to-insulator transition, crucially related
+to the connectivity among IrO6 octahedra. The subtle interplay between electron
+correlation and spin-orbit coupling leads to an almost pure Jeff = 1/2
+spin-orbit insulating state at the level of atomically-thin IrO2 monolayer with
+almost isolated IrO6 octahedra, leading to a predicted emerging state awaiting
+for experimental confirmation.",1702.04408v1
+2017-01-29,Built-in Homojunction Dominated Intrinsically Rectifying-Resistive Switching in NiO Nanodots for Selection Device-Free Memory Application,"The intrinsically rectifying-resistive switching (IR-RS) has been regarded as
+an effective way to address the crosstalk issue, due to the Schottky diodes
+formed at the metal/oxide interfaces in the ON states to suppress the sneak
+current at reverse biases. In this letter, we report for the first time another
+type of IR-RS that is related to the built-in homojunction. The IR-RS study was
+usually limited to macroscopic samples with micron-order pad-type electrodes,
+while this work is on NiO nanodots fabricated with ultrathin
+anodic-aluminum-oxide templates and acting as nanoscaled analogs of real
+devices. The NiO nanodots show high storage density and high uniformity, and
+the IR-RS behaviors are of good device performances in terms of retention,
+endurance, switching ratio and rectification ratio. The feasibility of the
+IR-RS for selection device-free memory application has been demonstrated, by
+calculating the maximum crossbar array size under the worst-case scenario to be
+3 Mbit.",1702.05665v1
+2017-01-26,Review of flexible and transparent thin-film transistors based on zinc oxide and related materials,"Flexible and transparent electronics presents a new era of electronic
+technologies. Ubiquitous applications involve wearable electronics, biosensors,
+flexible transparent displays, radio-frequency identifications (RFIDs),
+etc.Zinc oxide (ZnO) and related materials are the most commonly used inorganic
+semiconductors in flexible and transparent devices, owing to their high
+electrical performance, together with low processing temperature and good
+optical transparency.In this paper, we review recent advances in flexible and
+transparent thin-film transistors (TFTs) based on ZnO and related
+materials.After a brief introduction, the main progresses on the preparation of
+each component (substrate, electrodes, channel and dielectrics) are summarized
+and discussed. Then, the effect of mechanical bending on electrical performance
+was highlighted. Finally, we suggest the challenges and opportunities in future
+investigations.",1702.05669v1
+2017-03-02,Thermal conduction across a boron nitride and silicon oxide interface,"The needs for efficient heat removal and superior thermal conduction in
+nano/micro devices have triggered tremendous studies in low-dimensional
+materials with high thermal conductivity. Hexagonal boron nitride (h-BN) is
+believed to be one of the candidates for thermal management and heat
+dissipation due to its novel physical properties, i.e. thermal conductor and
+electrical insulator. Here we reported interfacial thermal resistance between
+few-layer h-BN and its silicon oxide substrate using differential 3 omega
+method. The measured interfacial thermal resistance is around ~1.6*10-8 m2K/W
+for monolayer h-BN and ~3.4*10-8 m2K/W for 12.8nm-thick h-BN in metal/h-BN/SiO2
+interfaces. Our results suggest that the voids and gaps between substrate and
+thick h-BN flakes limit the interfacial thermal conduction. This work provides
+a deeper understanding of utilizing h-BN flake as lateral heat spreader in
+electronic and optoelectronic nano/micro devices with further miniaturization
+and integration.",1703.00669v1
+2017-03-06,Phonon linewidth due to electron-phonon interactions with strong forward scattering in FeSe thin films on oxide substrates,"The discovery of an enhanced superconducting transition temperature $T_c$ in
+monolayers of FeSe grown on several oxide substrates has opened a new route to
+high-$T_c$ superconductivity through interface engineering. One proposal for
+the origin of the observed enhancement is an electron-phonon (e-ph) interaction
+across the interface that peaked at small momentum transfers. In this paper, we
+examine the implications of such a coupling on the phononic properties of the
+system. We show that a strong forward scattering leads to a sizable broadening
+of phonon lineshape, which may result in charge instabilities at
+long-wavelengths. However, we further find that the inclusion of Coulombic
+screening significantly reduces the phonon broadening. Our results show that
+one might not expect anomalously broad phonon linewidths in the FeSe interface
+systems, despite the fact that the e-ph interaction has a strong peak in the
+forward scattering (small $q$) direction.",1703.02013v1
+2017-03-09,Oxygen migration during resistance switching and failure of hafnium oxide memristors,"While the recent establishment of the role of thermophoresis/diffusion-driven
+oxygen migration during resistance switching in metal oxide memristors provided
+critical insights required for memristor modeling, extended investigations of
+the role of oxygen migration during ageing and failure remain to be detailed.
+Such detailing will enable failure-tolerant design, which can lead to enhanced
+performance of memristor-based next-generation storage-class memory. Here we
+directly observed lateral oxygen migration using in-situ synchrotron x-ray
+absorption spectromicroscopy of HfOx memristors during initial resistance
+switching, wear over millions of switching cycles, and eventual failure,
+through which we determined potential physical causes of failure. Using this
+information, we reengineered devices to mitigate three failure mechanisms, and
+demonstrated an improvement in endurance of about three orders of magnitude.",1703.03106v1
+2017-03-22,Intersubband polarons in oxides,"Intersubband (ISB) polarons result from the interaction of an ISB transition
+and the longitudinal optical (LO) phonons in a semiconductor quantum well (QW).
+Their observation requires a very dense two dimensional electron gas (2DEG) in
+the QW and a polar or highly ionic semiconductor. Here we show that in
+ZnO/MgZnO QWs the strength of such a coupling can be as high as 1.5 times the
+LO-phonon frequency due to the very dense 2DEG achieved and the large
+difference between the static and high-frequency dielectric constants in ZnO.
+The ISB polaron is observed optically in multiple QW structures with 2DEG
+densities ranging from $5\times 10^{12}$ to $5\times 10^{13}$ cm$^{-2}$, where
+an unprecedented regime is reached in which the frequency of the upper ISB
+polaron branch is three times larger than that of the bare ISB transition. This
+study opens new prospects to the exploitation of oxides in phenomena happening
+in the ultrastrong coupling regime.",1703.07743v1
+2017-03-29,Superconducting qubits on silicon substrates for quantum device integration,"We present the fabrication and characterization of transmon qubits formed
+from aluminum Josephson junctions on two different silicon-based substrates:
+(i) high-resistivity silicon (Si) and (ii) silicon-on-insulator (SOI). Key to
+the qubit fabrication process is the use of an anhydrous hydrofluoric vapor
+process which removes silicon surface oxides without attacking aluminum, and in
+the case of SOI substrates, selectively removes the lossy buried oxide
+underneath the qubit region. For qubits with a transition frequency of
+approximately $5$GHz we find qubit lifetimes and coherence times comparable to
+those attainable on sapphire substrates ($T_{1,\text{Si}} = 27\mu$s,
+$T_{2,\text{Si}} = 6.6\mu$s; $T_{1,\text{SOI}} = 3.5\mu$s, $T_{2,\text{SOI}} =
+2.2\mu$s). This qubit fabrication process in principle permits co-fabrication
+of silicon photonic and mechanical elements, providing a route towards
+chip-scale integration of electro-opto-mechanical transducers for quantum
+networking of superconducting microwave quantum circuits.",1703.10195v2
+2017-08-22,Highly Confined Stacks of Graphene Oxide Sheets in Water,"Since the discovery of graphene oxide (GO), the most accessible of the
+precursors of graphene, this material has been widely studied for applications
+in science and technology. In this work, we describe a procedure to obtain GO
+dispersions in water at high concentrations, these highly dehydrated
+dispersions being in addition fully redispersible by dilution. With the
+availability of such concentrated samples, it was possible to investigate the
+structure of hydrated GO sheets in a previously unexplored range of
+concentrations, and to evidence a structural phase transition. Tentatively
+applying models designed for describing the small-angle scattering curve in the
+Smectic A (or L$_{\alpha}$) phase of lyotropic systems, it was possible to
+extract elastic parameters characterising the system on the dilute side of the
+transition, thereby evidencing the relevance of both electrostatic and steric
+(Helfrich) interactions in stabilising aqueous lamellar stacks of GO sheets",1708.06661v2
+2017-08-23,One-step deposition and in-situ reduction of graphene oxide in glass microcapillaries and application to photonics,"Films of graphene oxide (GO) were produced on the inner walls of glass
+microcapillaries via insertion of a GO water suspension followed by quick
+drying with a hot finger (no previous surface functionalization required).
+Individual capillaries from an array could also be selectively GO coated. Raman
+hyperspectral images revealed the films to be continuous along tens of
+centimeters. Furthermore, the films could be thermally reduced through an
+annealing process, which also decreased the concentration of defects. As a
+proof of principle application, the microcapillaries of photonic crystal fibers
+were covered with a GO film, leading to the demonstration of fiber polarizers
+and mode lockers for pulsed fiber lasers. A comparison between GO- and reduced
+GO-coated fibers revealed that shorter pulses are obtained with the latter.",1708.06954v1
+2017-08-29,Commensurate Stripes and Phase Coherence in Manganites Revealed with Cryogenic Scanning Transmission Electron Microscopy,"Incommensurate charge order in hole-doped oxides is intertwined with exotic
+phenomena such as colossal magnetoresistance, high-temperature
+superconductivity, and electronic nematicity. Here, we map at atomic resolution
+the nature of incommensurate order in a manganite using scanning transmission
+electron microscopy at room temperature and cryogenic temperature ($\sim$ 93K).
+In diffraction, the ordering wavevector changes upon cooling, a behavior
+typically associated with incommensurate order. However, using real space
+measurements, we discover that the underlying ordered state is
+lattice-commensurate at both temperatures. The cations undergo picometer-scale
+($\sim $6-11 pm) transverse displacements, which suggests that charge-lattice
+coupling is strong and hence favors lattice-locked modulations. We further
+unearth phase inhomogeneity in the periodic lattice displacements at room
+temperature, and emergent phase coherence at 93K. Such local phase variations
+not only govern the long range correlations of the charge-ordered state, but
+also results in apparent shifts in the ordering wavevector. These
+atomically-resolved observations underscore the importance of lattice coupling
+and provide a microscopic explanation for putative ""incommensurate"" order in
+hole-doped oxides.",1708.08871v1
+2017-08-30,Tuning up or down the critical thickness in LaAlO3/SrTiO3 through in situ deposition of metal overlayers,"The quasi 2D electron system (q2DES) that forms at the interface between
+LaAlO3 and SrTiO3 has attracted much attention from the oxide electronics
+community. One of its hallmark features is the existence of a critical LaAlO3
+thickness of 4 unit-cells (uc) for interfacial conductivity to emerge. In this
+paper, the chemical, electronic, and transport properties of LaAlO3/SrTiO3
+samples capped with different metals grown in a system combining pulsed laser
+deposition, sputtering, and in situ X-ray photoemission spectroscopy are
+investigated. The results show that for metals with low work function a q2DES
+forms at 1-2 uc of LaAlO3 and is accompanied by a partial oxidation of the
+metal, a phenomenon that affects the q2DES properties and triggers the
+formation of defects. In contrast, for noble metals, the critical thickness is
+increased above 4 uc. The results are discussed in terms of a hybrid mechanism
+that incorporates electrostatic and chemical effects.",1708.09189v1
+2018-02-02,Electrofluorochromism at the single molecule level,"The interplay between the oxidation state and the optical properties of
+molecules plays a key role for applications in displays, sensors or
+molecular-based memories. The fundamental mechanisms occurring at the level of
+a single-molecule have been difficult to probe. We used a scanning tunneling
+microscope (STM) to characterize and control the fluorescence of a single
+Zn-phthalocyanine radical cation adsorbed on a NaCl-covered Au(111) sample. The
+neutral and oxidized states of the molecule were identified on the basis of
+their fluorescence spectra that revealed very different emission energies and
+vibronic fingerprints. The emission of the charged molecule was controlled by
+tuning the thickness of the insulator and the plasmons localized at the apex of
+the STM tip. In addition, sub-nanometric variations of the tip position were
+used to investigate the charging and electroluminescence mechanisms.",1802.00764v2
+2017-12-25,Combined Oxy-fuel Magnetohydrodynamic Power Cycle,"Oxy-fuel carbon capture in power plants is a relatively new concept aiming at
+reducing carbon dioxide emissions from the plants. This is achieved by burning
+the fossil fuel using oxygen as oxidizer with no nitrogen, thereby rendering
+the exhaust gases very rich in carbon dioxide (after condensing water vapor by
+cooling), which facilitates its capture for environmental or commercial
+purposes. Despite the worldwide interest in oxy-fuel carbon capture, its
+progress is at risk given the large energy needed to separate oxygen from air
+in order to provide the oxidizer, thereby hindering further progress of this
+concept toward large-scale applications. This paper focuses on alleviating this
+drawback of oxy-fuel combustion by making it more attractive through combining
+it with another concept, namely magnetohydrodynamic (MHD) power generators. The
+end product is a power plant operating on a combined cycle composed of a
+topping MHD ultra-high-temperature cycle with direct electricity extraction
+from plasma, followed by a bottoming steam cycle with conventional
+turbo-generators. Different design aspects and simplified technical analysis
+for the MHD generator are presented.",1802.02039v1
+2018-02-04,Characterization of spin coated Zn doped cupric oxide thin films,"Thin films of Zn2+ doped cupric oxide (CuO) were synthesized using spin
+coating technique starting from a solution with Cu and Zn. The speed of spin
+coating and time duration were varied to fabricate a film with required uniform
+thickness. Samples were subsequently annealed in air at different annealing
+temperatures to crystallize the phase of CuO. Doping concentration of Zn2+ was
+varied up to weight percentage of 10%. Structural properties of samples were
+determined using X-ray diffraction technique. Particle size, dislocation
+density and strain at different doping concentrations were determined using XRD
+patterns. Optical properties were measured by means of UV/Vis spectrometer.
+Optical band gap of CuO could be tailored by doping a trace amount of Zn2+. The
+optical band gap decreases with increase of particle size. The particle size,
+dislocation density, strain and optical band gap have a turning point close to
+the doping concentration of 6%.",1802.02886v1
+2018-02-22,Toward High Temperature Quasi-two-dimensional Superconductivity,"The demonstration of a quasi-two-dimensional electron gas (2DEG) and
+superconducting properties in LaAlO$_3$/SrTiO$_3$ heterostructures has
+stimulated intense research activity in recent ten years. The 2DEG has unique
+properties that are promising for applications in all-oxide electronic devices.
+The superconductivity in such heterostructures has been observed below 300 mK.
+For superconductivity applications it is desirable to have more wide
+temperature of the existence range and the ability to control superconductivity
+properties by external stimulus. Based on first-principles calculations and
+theoretical consideration we show that all-oxide heterostructures incorporating
+ferroelectric constituent, such as BaTiO$_3$/La$_2$CuO$_4$, allow creating
+2DEG. We predict a possibility of a high temperature guasi-two-dimensional
+superconductivity state. This state could be switchable between superconducting
+and conducting states by ferroelectric polarization reversal. We also discuss
+that such structures must be more simple for preparation. The proposed concept
+of ferroelectrically controlled interface superconductivity offers the
+possibility to design novel electronic devices.",1802.08569v1
+2018-03-30,Growth of Thin Oxidation-Resistive Crystalline Si Nanostructures on Graphene,"We report the growth of Si nanostructures, either as thin films or
+nanoparticles, on graphene substrates. The Si nanostructures are shown to be
+single crystalline, air stable and oxidation resistive, as indicated by the
+observation of a single crystalline Si Raman mode at around 520 cm-1, a STM
+image of an ordered surface structure under ambient condition, and a Schottky
+junction with graphite. Ultra-thin silicon regions exhibit silicene-like
+behavior, including a Raman mode at around 550 cm-1, a triangular lattice
+structure in STM that has distinctly different lattice spacing from that of
+either graphene or thicker Si, and metallic conductivity of up to 500 times
+higher than that of graphite. This work suggests a bottom-up approach to
+forming a Si nanostructure array on a large scale patterned graphene substrate
+for fabricating nanoscale Si electronic devices.",1804.00072v1
+2018-04-08,New optimization scheme to obtain interaction potentials for oxide glasses,"We propose a new scheme to parameterize effective potentials that can be used
+to simulate atomic systems such as oxide glasses. As input data for the
+optimization, we use the radial distribution functions of the liquid and the
+vibrational density of state of the glass, both obtained from ab-initio
+simulations, as well as experimental data on the pressure dependence of the
+density of the glass. For the case of silica, we find that this new scheme
+facilitates finding pair potentials that are significantly more accurate than
+previous ones even if the functional form is the same, thus demonstrating that
+even simple two-body potentials can be superior to more complex three-body
+potentials. We have tested the new potential by calculating the pressure
+dependence of the elastic moduli and find a good agreement with the
+corresponding experimental data.",1804.02741v1
+2018-04-13,Aggregation and Electronically-Induced Migration of Oxygen Vacancies in TiO2 Anatase,"The influence of the electric field and electric current on the behavior of
+oxygen vacancies (VOs) in TiO2 anatase was investigated with Scanning Tunneling
+Microscopy (STM). At the anatase (101) surface VOs are not stable; they migrate
+into the bulk at temperatures above 200 K. Scanning a clean anatase (101)
+surface at a sample bias greater than +4.3 V results in surface VOs in the
+scanned area, suggesting that subsurface VOs migrate back to the surface. To
+test this hypothesis, surface VOs were first created through bombardment with
+energetic electrons. The sample was then mildly annealed, which caused the VOs
+to move to the subsurface region, where they formed vacancy clusters. These VO
+clusters have various, distinct shapes. Scanning VO clusters with a high STM
+bias reproducibly converts them back into groupings of surface VO, with a
+configuration that is characteristic for each type of cluster. The dependence
+of the subsurface-to-surface VO migration on the applied STM bias voltage,
+tunneling current, and sample temperature was investigated systematically. The
+results point towards a key role of energetic, 'hot' electrons in this process.
+The findings are closely related to the memristive behavior of oxides and
+oxygen diffusion in solid-oxide membranes.",1804.04920v1
+2018-04-22,Toward a topological scenario for high-temperature superconductivity of copper oxides,"The structure of the joint phase diagram demonstrating high-$T_c$
+superconductivity of copper oxides is studied on the basis of the theory of
+interaction-induced flat bands. Prerequisites of an associated topological
+rearrangement of the Landau state are established, and related non-Fermi-liquid
+(NFL) behavior of the normal states of cuprates is investigated. We focus on
+manifestations of this behavior in the electrical resistivity $\rho(T)$,
+especially the observed gradual crossover from normal-state $T$-linear behavior
+$\rho(T,x)=A_1(x)T$ at doping $x$ below the critical value $x_c^h$ for
+termination of superconductivity, to $T$-quadratic behavior at $x>x_c^h$, which
+is incompatible with predictions of the conventional quantum-critical-point
+scenario. It is demonstrated that at $x<x^h_c$, in agreement with available
+experimental data, the coefficient $A_1( x)$ is decomposed into the product of
+two factors, one of which changes linearly with doping $x$, while the second is
+universal, being of the Planckian form.",1804.08177v2
+2018-04-27,High-pressure Raman study on the superconducting pyrochlore oxide Cd2Re2O7,"The superconducting pyrochlore oxide Cd2Re2O7 (Tc = 1 K), which is now
+considered as a candidate of the spin-orbit-coupled metal, shows an
+inversion-symmetry-breaking structural transition at Ts1 = 200 K. Ts1 decreases
+with increasing pressure and disappears at around Pc = 4:2GPa, where at least
+four high-pressure phases with tiny structural distortions are suggested by
+means of powder X-ray diffraction [Yamaura PRB 2017]. We have carried out Raman
+scattering experiments to investigate changes in the crystal symmetry under
+high pressures up to 4.8 GPa. A structural transition at 1.9-3.0 GPa and the
+recovery of inversion symmetry above Pc are observed at 12 K.",1804.10487v1
+2018-04-28,Effect of the reduction process on the field emission performance of reduced graphene oxide cathodes,"The electron field emission (FE) properties of reduced graphene oxide (rGO)
+cathodes produced by three different reduction methods were assessed and
+compared. In particular, chemical reduction techniques, using either NaOH or
+KOH as reducing agents, were compared with thermal reduction (TR) methods. Xray
+photoelectron spectroscopy (XPS) measurements revealed that different reduction
+techniques led to different GO lattice parameters. Furthermore, the work
+function measured with ultraviolet photoelectron spectroscopy (UPS) varied
+among the samples giving rise to different electron emission characteristics.
+In particular, the cathodes prepared by the TR method presented the best FE
+performance, showing a turnon field of as low as ca. 1.8 V mm^-1 and a field
+enhancement factor of ca. 1300, which was very close however to that shown by
+the NaOH-reduced sheets. The worst FE properties were exhibited by the
+KOH-reduced nanosheets. In light of the above results, the role of the
+different reduction techniques as well as the final rGO lattice characteristics
+with regards to the emission performance are evaluated and discussed.",1804.10813v1
+2018-11-16,Ensemble versus Local Restructuring of Core-shell Nickel-Cobalt Nanoparticles upon Oxidation and Reduction Cycles,"Bimetallic nanoparticles are widely studied, for example in catalysis.
+However, possible restructuring in the environment of use, such as segregation
+or alloying, may occur. Taken individually, state-of-the-art analytical tools
+fail to give an overall picture of these transformations. This study combines
+an ensemble analysis (near-ambient-pressure X-ray photoelectron spectroscopy)
+with a local analysis (environmental transmission electron microscopy) to
+provide an in situ description of the restructuring of core--shell
+nickel-cobalt nanoparticles exposed to cycles of reduction and oxidation. It
+reveals a partial surface alloying accompanied by fragmentation of the shell
+into smaller clusters, which is not reversible. Beyond this case study, the
+methodology proposed here should be applicable in a broad range of studies
+dealing with the reactivity of mono- or bi-metallic metal nanoparticles.",1811.06900v1
+2018-11-21,Coordination corrected ab initio formation enthalpies,"The correct calculation of formation enthalpy is one of the enablers of
+ab-initio computational materials design. For several classes of systems (e.g.
+oxides) standard density functional theory produces incorrect values. Here we
+propose the ""Coordination Corrected Enthalpies"" method (CCE), based on the
+number of nearest neighbor cation-anion bonds, and also capable of correcting
+relative stability of polymorphs. CCE uses calculations employing the Perdew,
+Burke and Ernzerhof (PBE), Local Density Approximation (LDA) and Strongly
+Constrained and Appropriately Normed (SCAN) exchange correlation functionals,
+in conjunction with a quasiharmonic Debye model to treat zero-point vibrational
+and thermal effects. The benchmark, performed on binary and ternary oxides
+(halides), shows very accurate room temperature results for all functionals,
+with the smallest mean absolute error of 27 (24) meV/atom obtained with SCAN.
+The zero-point vibrational and thermal contributions to the formation
+enthalpies are small and with different signs - largely cancelling each other.",1811.08952v2
+2018-10-17,"Compact Modeling of I-V Characteristics, Temperature Dependency, Variations, and Noise of Integrated, Reproducible Metal-Oxide Memristors","We present a comprehensive phenomenological model for the crossbar integrated
+metal-oxide continuous-state memristors. The model consists of static and
+dynamic equations, which are obtained by fitting a large amount of experimental
+data, collected on several hundred devices. The static equation describes the
+device current, at non-disturbing voltages, as a sum of three components,
+representing the average behavior and its device-to-device and temporal
+variations. All three components are expressed as functions of the applied
+voltage, ambient temperature, and the current memory state. The dynamic
+equation models the change in the memory state as a function of the applied
+voltage stress and the current memory state, and is also expressed as a sum of
+the average and the device-to-device variation terms. Both equations are
+explicit, computationally inexpensive, and suitable for SPICE modeling. At the
+same time, the model has good predictive power, which is supported by the
+validation results. The presented model is useful for realistic simulations of
+various mixed-signal computing circuits, such as image compression and image
+classification applications, discussed in this paper.",1811.10385v1
+2018-11-27,Directional freezing of binary colloidal suspensions: A model for size fractionation of graphene oxide,"The performance of graphene oxide(GO)-based materials strongly depends on the
+lateral size and size distribution of GO nanosheets. Various methods are
+employed to prepare GO nanosheets with a narrow size distribution. One of the
+promising method was proposed recently by directionally freezing of a GO
+aqueous dispersion at a controlled growth rate of the freezing front. We
+develop a theoretic model of binary colloids suspension, incorporating both the
+moving freezing boundary and the preferential adsorption of colloidal particles
+to the ice phase. We numerically solve the coupled diffusion equations and
+present state diagrams of size fractionation. Selective trapping of colloids
+according to their size can be achieved by a suitable choice of the
+experimental parameters, such as the adsorption rates and the freezing speed.",1811.11070v1
+2018-11-27,Second Neighbor Electron Hopping and Pressure Induced Topological Quantum Phase Transition in Insulating Cubic Perovskites,"Perovskite structure is one of the five symmetry families suitable for
+exhibiting topological insulator phase. However, none of the halides and oxides
+stabilizing in this structure exhibit the same. Through density functional
+calculations on cubic perovskites (CsSnX$_3$ ; X = Cl, Br, and I), we predict a
+band insulator -- Dirac semimetal -- topological insulator phase transition
+with uniform compression. With the aid of a Slater-Koster tight binding
+Hamiltonian, we show that, apart from the valence electron count, the band
+topology of these perovksites is determined by five parameters involving
+electron hopping among the Sn-{s, p} orbitals. These parameters monotonically
+increase with pressure to gradually transform the positive band gap to a
+negative one and thereby enable the quantum phase transition. The universality
+of the mechanism of phase transition is established by examining the band
+topology of Bi based oxide perovskites. Dynamical stability of the halides
+against pressure strengthens the experimental relevance.",1811.11081v1
+2018-11-30,Dichotomy of the Photo Induced 2-Dimensional Electron Gas on SrTiO$_3$ Surface Terminations,"Oxide materials are important candidates for the next generation of
+electronics due to a wide array of desired properties which they can exhibit
+alone or when combined with other materials. While SrTiO$_3$ (STO) is often
+considered a prototypical oxide, it too hosts a wide array of unusual
+properties including a two dimensional electron gas (2DEG) which can form at
+the surface when exposed to UV light. Using layer-by-layer growth of high
+quality STO films, we show that the 2DEG only forms with the SrO termination
+and not with the TiO$_2$ termination, contrary to expectation. This behavior is
+similarly seen in BaTiO$_3$ (BTO), in which the 2DEG is only observed for BaO
+terminated films. These results will allow for a deeper understanding, and
+better control, of the electronic structure of titanate films, substrates and
+heterostructures.",1811.12652v1
+2018-11-30,Engineering mass transport properties in oxide ionic and mixed ionic electronic thin film ceramic conductors for energy applications,"New emerging disciplines such as Nanoionics and Iontronics are dealing with
+the exploitation of mesoscopic size effects in materials, which become visible
+(if not predominant) when downsizing the system to the nanoscale. Driven by the
+worldwide standardisation of thin film deposition techniques, the access to
+radically different properties than those found in the bulk macroscopic systems
+can be accomplished. This opens up promising approaches for the development of
+advanced microdevices, by taking advantage of the nanostructural deviations
+found in nanometre sized, interface dominated materials compared to the ideal
+relaxed structure of the bulk. A completely new set of functionalities can be
+explored, with implications in many different fields such as energy conversion
+and storage, or information technologies. This manuscript reviews the
+strategies, employed and foreseen, for engineering mass transport properties in
+thin film ceramics, with the focus in oxide ionic and mixed ionic electronic
+conductors and their application in micro power sources.",1811.12771v1
+2019-05-02,The inequivalent substitution on Ca site of cubic CaTiO3 perovskite for transparent conductive oxides from USPEX and DFT,"Based on genetic evolution algorithm, universal structure predictor USPEX
+assists to explore the most stable structure from Na+ substituting Ca2+ under
+variable concentration, for p type transparent conductive oxide application.
+The study finds 2 atoms of NaCa maintain the octahedral packing and cubic phase
+without the presence of oxygen vacancy, but the electron loss causes in fermi
+level entering into valence band, realizing p type TCOs character. While others
+still remain insulator character due to the compensation of oxygen vacancy.
+Applying Al3+ substituting Ca2+ achieve the fermi level into conduction band
+with n-type TCOs, with the symmetry of tetragonal phase. And the transport
+properties for p- type Ca0.75Na0.25TiO3 and n-type Ca0.75Al0.25TiO3 are
+calculated, the mobility in p- type Ca0.75Na0.25TiO3 is more superior owing to
+its curvature edge.",1905.00548v1
+2019-05-05,Metal oxide nanomaterials for pseudocapacitors,"With the rapid development of economy, the consumption of fossil fuels, and
+the increasing environment pollution, there is in urgent need of seeking clean
+and renewable energy sources, as well as highly efficient and low-cost energy
+storage technologies. Concerning electrochemically active materials, transition
+metal oxides (TMOs) are regarded as the most promising candidates for the next
+generation SCs and have been widely reported. Therefore, in this review, we
+mainly pay attention to TMOs with excellent electrochemical performance. This
+review is divided into four parts: (a) the background including energy storage
+mechanisms and electrochemical characterizations of SCs; (b) various kinds of
+TMOs for SCs are analyzed in detail involved in crystal structure,
+conductivity, and energy storage mechanism; (c) hybridizations with other
+materials to improve the electrochemical performance of TMOs are summarized and
+discussed; (d) a perspective and short remarks about the development and design
+of TMOs for superior performance SCs are shown.",1905.01766v2
+2019-05-09,More than 3-mm-long carrier diffusion and strong absorption over the full solar spectrum in copper oxide and selenium composite film,"Usually, single-crystal material has a longer carrier diffusion length due to
+fewer defects. Here, we report a nano/amorphous copper oxide and selenium (COS)
+composite film prepared by radio frequency magnetron co-sputtering of CuO and
+Se and post annealing. The photo-generated carriers in the COS film can diffuse
+very far (3.147 mm). Additionally, the COS film can strongly absorb light over
+the entire solar spectrum region (250-2500 nm) (average absorptance is ~80%).
+These results indicate that the COS composite is an excellent material and can
+be used in solar cells and other photo-electric devices.",1905.03432v1
+2019-05-14,Revealing the complex nature of bonding in binary high-pressure compound FeO$_2$,"Extreme pressures and temperatures are known to drastically affect the
+chemistry of iron oxides resulting in numerous compounds forming homologous
+series $n$FeO$\cdot m$Fe$_2$O$_3$ and the appearance of FeO$_2$. Here, based on
+the results of \emph{in situ} single-crystal X-ray diffraction, M\""ossbauer
+spectroscopy, X-ray absorption spectroscopy, and DFT+dynamical mean-field
+theory calculations we demonstrate that iron in high pressure cubic FeO$_2$ and
+isostructural FeO$_2$H$_{0.5}$ is ferric (Fe$^{3+}$), and oxygen has a formal
+valence less than two. Reduction of oxygen valence from 2, common for oxides,
+down to 1.5 can be explained by a formation of a localized hole at oxygen
+sites.",1905.05497v2
+2019-05-15,Coupled Cluster Benchmark of New Density Functionals and Domain Pair Natural Orbital Methods: Mechanisms of Hydroarylation and Oxidative Coupling Catalyzed by Ru(II) Chloride Carbonyls,"In the present work, we tested the performance of several new functionals for
+studying the mechanisms of concurrent reaction of hydroarylation and oxidative
+coupling catalyzed by Ru(II) chloride carbonyls. We find that DLPNO-CCSD(T) is
+an acceptable substitute for full canonical CCSD(T) calculations; that the
+recent {\omega}B97X-V and {\omega}B97M-V functionals exhibit superior
+performance to commonly used DFT functionals; and that the revised DSD-PBEP86
+double hybrid represents an improvement over the original, even though
+transition metals were not involved in its parametrization.",1905.06168v2
+2019-05-16,Tuning the work function of graphene toward application as anode and cathode,"The rapid technological progress in the 21st century demands new
+multi-functional materials applicable to a wide variety of industries.
+Two-dimensional (2D) materials are predicted to have a revolutionary impact on
+the cost, size, weight, and functions of future electronic and optoelectronic
+devices. Graphene, which shows potential as an alternative to conventional
+conductive transparent metal oxides, may play a central role. Since its work
+function (WF) is tunable, graphene exhibits the interesting ability to serve
+two different roles in electronic and optoelectronic devices, both as an anode
+and a cathode. After introducing some basic concepts, this work reviews the
+most important advances in controlling the tuned WF of graphene, highlighting
+special features of graphene electronic band structure and recognizing
+different methods for measuring WF. The impact of thickness, type of contact,
+chemical doping, UV and plasma treatments, defects, and functional groups of
+graphene oxide are considered and related with the applications of the
+modulated material. The results of the review, organized in lookup tables, have
+been used to identify the advantages and main challenges of the tuning methods.",1905.06594v1
+2019-05-23,Laser machined ultrathin microscale platinum thermometers on transparent oxide substrates,"Ultrathin microscale resistive thermometers are of key value to many
+applications. Here we have fabricated a laser machined 50 ${\mu}$m wide and 50
+nm thick serpentine Pt thin film sensor capable of sensing temperatures up to
+650 ${^\circ}$ C over multiple heating and cooling cycles. Various materials
+and associated processing conditions were studied, including both sapphire and
+silica as transparent substrates, alumina and TiO2 as adhesion layers, and
+lastly alumina and silicon oxide as capping layer. In-situ resistance
+monitoring helps to verify the multi-cycle stability of the sensor and guide
+the optimization. 10 ${\mu}$m sized sensors can be laser machined but will not
+survive multiple heating and cooling cycles. We demonstrate that the sensors
+with amorphous Ge thin layers can also repeatably measure temperatures up to
+650 ${^\circ}$ C. It is anticipated that this sensor can be used for fast and
+high spatial resolution temperature probing for laser processing applications.",1905.09812v1
+2019-05-25,Actively tunable terahertz electromagnetically induced transparency analogue based on vanadium-oxide-assisted metamaterials,"Recently, phase-change materials (PCMs) have drawn more attention due to the
+dynamically tunable optical properties. Here, we investigate the active control
+of electromagnetically induced transparency (EIT) analogue based on terahertz
+(THz) metamaterials integrated with vanadium oxide (VO2). Utilizing the
+insulator-to-metal transition of VO2, the amplitude of EIT peak can be actively
+modulated with a significant modulation depth. Meanwhile the group delay within
+the transparent window can also be dynamically tuned, achieving the active
+control of slow light effect. Furthermore, we also introduce independently
+tunable transparent peaks as well as group delay based on a double-peak EIT
+with good tuning performance. Finally, based on broadband EIT, the active
+tuning of quality factor of the EIT peak is also realized. This work introduces
+active EIT control with more degree of freedom by employing VO2, and can find
+potential applications in future wireless and ultrafast THz communication
+systems as multi-channel filters, switches, spacers, logic gates and
+modulators.",1905.10623v1
+2019-05-30,Layer-Resolved Ultrafast XUV Measurement of Hole Transport in a Ni-TiO2-Si Photoanode,"Metal-oxide-semiconductor junctions are central to most electronic and
+optoelectronic devices. Here, the element-specificity of broadband extreme
+ultraviolet (XUV) ultrafast pulses is used to measure the charge transport and
+recombination kinetics in each layer of a Ni-TiO2-Si junction. After
+photoexcitation of silicon, holes are inferred to transport from Si to Ni
+ballistically in ~100 fs, resulting in spectral shifts in the Ni M2,3 XUV edge
+that are characteristic of holes and the absence of holes initially in TiO2.
+Meanwhile, the electrons are observed to remain on Si. After picoseconds, the
+transient hole population on Ni is observed to back-diffuse through the TiO2,
+shifting the Ti spectrum to higher oxidation state, followed by electron-hole
+recombination at the Si-TiO2 interface and in the Si bulk. Electrical
+properties, such as the hole diffusion constant in TiO2 and the initial hole
+mobility in Si, are fit from these transient spectra and match well with values
+reported previously.",1905.13097v1
+2020-07-07,Nanoelectrodes for intracellular measurements of reactive oxygen and nitrogen species in single living cells,"Reactive oxygen and nitrogen species (ROS and RNS) play important roles in
+various physiological processes (e.g., phagocytosis) and pathological
+conditions (e.g., cancer). The primary ROS/RNS, viz., hydrogen peroxide,
+peroxynitrite ion, nitric oxide, and nitrite ion, can be oxidized at different
+electrode potentials and therefore detected and quantified by electroanalytical
+techniques. Nanometer-sized electrochemical probes are especially suitable for
+measuring ROS/RNS in single cells and cellular organelles. In this article, we
+survey recent advances in localized measurements of ROS/RNS inside single cells
+and discuss several methodological issues, including optimization of
+nanoelectrode geometry, precise positioning of an electrochemical probe inside
+a cell, and interpretation of electroanalytical data.",2007.03245v1
+2020-07-16,ENZ materials and Anisotropy: Enhancing Nonlinear Optical Interactions at the Nanoscale in Metal/Conducting-Oxide Multilayer Stacks,"Epsilon-near-zero materials are exceptional candidates for studying
+electrodynamics and nonlinear optical processes at the nanoscale. We
+demonstrate that by alternating a metal and a highly doped conducting-oxide,
+the epsilon-near-zero regime may be accessed resulting in an anisotropic,
+composite nanostructure that significantly enhances nonlinear interactions.
+Using two independent and different computation techniques we show that the
+structure can enhance the local field intensity by nearly two orders of
+magnitudes, in large part due to the onset of the effective anisotropy. The
+investigation of the multilayer nanostructure using a microscopic, hydrodynamic
+approach also sheds light on the roles of two competing contributions that are
+for the most part overlooked, but that can significantly modify linear and
+nonlinear responses of the structure: nonlocal effects, which blueshift the
+resulting resonance, and the hot electron nonlinearity, which redshifts the
+plasma frequency as the effective mass of free electrons increases as a
+function of incident power density. Finally, we show that, even in absence of
+second order bulk nonlinearity, second order nonlinear processes are also
+significantly enhanced by the layered structure.",2007.08312v1
+2010-05-13,Probing top-gated field effect transistor of reduced graphene oxide monolayer made by dielectrophoresis,"We demonstrate top-gated field effect transistor made of reduced graphene
+oxide (RGO) monolayer (graphene) by dielectrophoresis. Raman spectrum of RGO
+flakes of typical size of 5{\mu}m x 5{\mu}m show a single 2D band at 2687 cm-1,
+characteristic of a single layer graphene. The two probe current - voltage
+measurements of RGO flakes, deposited in between the patterned electrodes with
+a gap of 2.5 {\mu}m using a.c. dielectrophoresis show ohmic behavior with a
+resistance of ~ 37k{\Omega}. The temperature dependence of the resistance (R)
+of RGO measured between temperatures 305 K to 393 K yields temperature
+coefficient of resistance [dR/dT]/R ~ -9.5x10-4 K-1, same as mechanically
+exfoliated single layer graphene. The field effect transistor action was
+obtained by electrochemical top-gating using solid polymer electrolyte (PEO +
+LiClO4) and Pt wire. Ambipolar nature of graphene flakes is observed upto a
+doping level of ~ 6x1012/cm2 and carrier mobility of ~ 50 cm2V-1sec-1. The
+source - drain current characteristics shows a tendency of current saturation
+at high source - drain voltage which is analyzed quantitatively by a diffusive
+transport model.",1005.2258v1
+2010-05-20,Hot carrier diffusion in graphene,"We report an optical study of charge transport in graphene. Diffusion of hot
+carriers in epitaxial graphene and reduced graphene oxide samples are studied
+using an ultrafast pump-probe technique with a high spatial resolution.
+Spatiotemporal dynamics of hot carriers after a point-like excitation are
+monitored. Carrier diffusion coefficients of 11,000 and 5,500 squared
+centimeters per second are measured in epitaxial graphene and reduced graphene
+oxide samples, respectively, with a carrier temperature on the order of 3,600
+K. The demonstrated optical techniques can be used for non-contact and
+non-invasive in-situ detection of transport properties of graphene.",1005.3850v2
+2013-08-04,In vitro toxicity of nanoceria: effect of coating and stability in biofluids,"Due to the increasing use of nanometric cerium oxide in applications,
+concerns about the toxicity of these particles have been raised and have
+resulted in a large number of investigations. We report here on the
+interactions between 7 nm anionically charged cerium oxide particles and living
+mammalian cells. By a modification of the particle coating including
+low-molecular weight ligands and polymers, two generic behaviors are compared:
+particles coated with citrate ions that precipitate in biofluids and particles
+coated with poly(acrylic acid) that are stable and remain nanometric. We find
+that nanoceria covered with both coating agents are taken up by mouse
+fibroblasts and localized into membrane-bound compartments. However, flow
+cytometry and electron microscopy reveal that as a result of their
+precipitation, citrate-coated particles interact more strongly with cells. At
+cerium concentration above 1 mM, only citrate-coated nanoceria (and not
+particles coated with poly(acrylic acid)) display toxicity and moderate
+genotoxicity. The results demonstrate that the control of the surface chemistry
+of the particles and its ability to prevent aggregation can affect the toxicity
+of nanomaterials.",1308.0800v1
+2013-08-08,Weak Coupling BCS-like Superconductivity in the Pnictide Oxide Ba$_{1-x}$Na$_x$Ti$_2$Sb$_2$O (x=0 and 0.15),"We report the results of low-temperature heat capacity measurements of the
+pnictide oxide superconductor BaTi$_2$Sb$_2$O doped with sodium. The
+temperature and field dependent heat capacity data are well described by a
+single-gap BCS theory. The estimated values for the normal state Sommerfeld
+constant, the heat capacity jump at $T_c$, and the electron-phonon coupling
+constant are in favor of a conventional weak coupling superconductivity
+mediated by electron-phonon interaction. The results are discussed with regard
+to and compared with recent first principle calculations.",1308.1880v1
+2013-08-09,ALD grown zinc oxide with controllable electrical properties,"The paper presents results for zinc oxide films grown at low temperature
+regime by Atomic Layer Deposition (ALD). We discuss electrical properties of
+such films and show that low temperature deposition results in oxygen-rich ZnO
+layers in which free carrier concentration is very low. For optimized ALD
+process it can reach the level of 10^15 cm-3, while mobility of electrons is
+between 20 and 50 cm2/Vs. Electrical parameters of ZnO films deposited by ALD
+at low temperature regime are appropriate for constructing of the ZnO-based p-n
+and Schottky junctions. We demonstrate that such junctions are characterized by
+the rectification ratio high enough to fulfill requirements of 3D memories and
+are deposited at temperature 100degC which makes them appropriate for
+deposition on organic substrates.",1308.2064v1
+2013-08-12,Quantum confinement in perovskite oxide heterostructures: tight binding instead of nearly free electron picture,"Most recently, orbital-selective quantum well states of $d$ electrons have
+been experimentally observed in SrVO$_3$ ultrathin films [K. Yoshimatsu et.
+al., Science 333, 319 (2011)] and SrTiO$_3$ surfaces [A. F. Santander-Syro et.
+al., Nature 469, 189 (2011)]. Hitherto, one tries to explain these experiments
+by a nearly free electron (NFE) model, an approach widely used for delocalized
+electrons in semiconductor heterostructures and simple metal films. We show
+that a tight binding (TB) model is more suitable for describing
+heterostructures with more localized $d$ electrons. In this paper, we construct
+from first principles simple TB models for perovskite oxide heterostructures
+and surfaces. We show that the TB model provides a simple intuitive physical
+picture and yields, already with only two parameters, quantitatively much more
+reliable results, consistent with experiment.",1308.2615v1
+2013-08-25,CO2/oxalate Cathodes as Safe and Efficient Alternatives in High Energy Density Metal-Air Type Rechargeable Batteries,"We present theoretical analysis on why and how rechargeable metal-air type
+batteries can be made significantly safer and more practical by utilizing
+CO2/oxalate conversions instead of O2/peroxide or O2/hydroxide ones, in the
+positive electrode. Metal-air batteries, such as the Li-air one, may have very
+large energy densities, comparable to that of gasoline, theoretically allowing
+for long range all-electric vehicles. There are, however, still significant
+challenges, especially related to the safety of their underlying chemistries,
+the robustness of their recharging and the need of supplying high purity O2
+from air to the battery. We point out that the CO2/oxalate reversible
+electrochemical conversion is a viable alternative of the O2-based ones,
+allowing for similarly high energy density and almost identical voltage, while
+being much safer through the elimination of aggressive oxidant peroxides and
+the use of thermally stable, non-oxidative and environmentally benign oxalates
+instead.",1308.5457v2
+2013-08-26,Raman spectroscopy study of the interface structure in (CaCuO2)n/(SrTiO3)m superlattices,"Raman spectra of CaCuO2/SrTiO3 superlattices show clear spectroscopic marker
+of two structures formed in CaCuO2 at the interface with SrTiO3. For
+non-superconducting superlattices, grown in low oxidizing atmosphere, the 425
+cm-1 frequency of oxygen vibration in CuO2 planes is the same as for CCO films
+with infinite layer structure (planar Cu-O coordination). For superconducting
+superlattices grown in highly oxidizing atmosphere, a 60 cm-1 frequency shift
+to lower energy occurs. This is ascribed to a change from planar to pyramidal
+Cu-O coordination because of oxygen incorporation at the interface. Raman
+spectroscopy proves to be a powerful tool for interface structure
+investigation.",1308.5616v2
+2014-03-02,"Improper Ferroelectricity and Piezoelectric Responses in Rhombohedral ($A$,$A^{\prime}$)$B_2$O$_6$ Perovskite Oxides","High-temperature electronic materials are in constant demand as the required
+operational range for various industries increases. Here we design
+$(A,A^\prime)B_2$O$_6$ perovskite oxides with [111] ``rock salt"" $A$-site
+cation order and predict them to be potential high-temperature piezoelectric
+materials. By selecting bulk perovskites which have a tendency towards only
+out-of-phase $B$O$_6$ rotations, we avoid possible staggered ferroelectric to
+paraelectric phase transitions while also retaining non-centrosymmetric crystal
+structures necessary for ferro- and piezoelectricity. Using density functional
+theory calculations, we show that (La,Pr)Al$_2$O$_6$ and (Ce,Pr)Al$_2$O$_6$
+display spontaneous polarizations in their polar ground state structures; we
+also compute the dielectric and piezoelectric constants for each phase.
+Additionally, we predict the critical phase transition temperatures for each
+material from first-principles to demonstrate that the piezoelectric responses,
+which are comparable to traditional lead-free piezoelectrics, should persist to
+high temperature. These features make the rock salt $A$-site ordered aluminates
+candidates for high-temperature sensors, actuators, or other electronic
+devices.",1403.0151v1
+2014-03-10,Solvent Induced Proton Hopping at a Water-Oxide Interface,"Despite widespread interest, a detailed understanding of the dynamics of
+proton transfer at interfaces is lacking. Here we use ab initio molecular
+dynamics to unravel the connection between interfacial water structure and
+proton transfer for the widely studied and experimentally well-characterized
+water-ZnO$(10\bar{1}0)$ interface. We find that upon going from a single layer
+of adsorbed water to a liquid multilayer changes in the structure are
+accompanied by a dramatic increase in the proton transfer rate at the surface.
+We show how hydrogen bonding and rather specific hydrogen bond fluctuations at
+the interface are responsible for the change in the structure and proton
+transfer dynamics. The implications of this for the chemical reactivity and for
+the modelling of complex wet oxide interfaces in general are also discussed.",1403.2416v1
+2014-03-11,Electrical and thermal conductivities of reduced graphene oxide/polystyrene composites,"The author reports an experimental study of electrical and thermal transport
+in reduced graphene oxide (RGO)/polystyrene (PS) composites. The electrical
+conductivity ($\sigma$) of RGO/PS composites with different RGO concentrations
+at room temperature shows a percolation behavior with the percolation threshold
+of ~ 0.25 vol.%. Their temperature-dependent electrical conductivity follows
+Efros-Shklovskii (ES) variable range hopping (VRH) conduction in the
+temperature range of 30 to 300 K. The thermal conductivity ($\kappa$) of
+composites is enhanced by ~ 90 % as the concentration is increased from 0 to 10
+vol.%. The thermal conductivity of composites approximately linearly increases
+with increasing temperature from 150 to 300 K. Composites with a higher
+concentration show a stronger temperature dependence in the thermal
+conductivity.",1403.2467v2
+2016-11-04,Origin of multistate resistive switching in Ti/manganite/Si$O_x$/Si heterostructures,"We report on the growth and characterization of
+Ti/$La_{1/3}$$Ca_{2/3}$Mn$O_3$/Si$O_x$/n-Si memristive devices. We demonstrate
+that using current as electrical stimulus unveils an intermediate resistance
+state, in addition to the usual high and low resistance states that are
+observed in standard voltage controlled experiments. Based on thorough
+electrical characterization (impedance spectroscopy, current-voltage curves
+analysis), we disclose the contribution of three different microscopic regions
+of the device to the transport properties: an ohmic incomplete metallic
+filament, a thin manganite layer below the filament tip exhibiting
+Poole-Frenkel like conduction, and the SiOx layer with an electrical response
+well characterized by a Child-Langmuir law. Our results suggest that the
+existence of the SiOx layer plays a key role in the stabilization of the
+intermediate resistance level, indicating that the combination of two or more
+active RS oxides adds functionalities in relation to single-oxide devices. We
+understand that these multilevel devices are interesting and promising as their
+fabrication procedure is rather simple and they are fully compatible with
+standard Si-based electronics.",1611.01552v2
+2016-11-17,Large bipolarons and oxide superconductivity,"Large-bipolaron superconductivity is plausible with carrier densities well
+below those of conventional metals. Bipolarons form when carriers self-trap in
+pairs. Coherently moving large-bipolarons require extremely large ratios of
+static to optical dielectric-constants. The mutual Coulomb repulsion of a
+planar large-bipolarons paired carriers drives it to a four-lobed shape. A
+phonon-mediated attraction among large-bipolarons propels their condensation
+into a liquid. This liquids excitations move slowly with a huge effective mass.
+Excitations concomitant weak scattering by phonons produces a moderate
+low-temperature dc resistivity that increases linearly with rising temperature.
+With falling temperature an energy gap opens between large-bipolarons
+excitations and those of their self-trapped electronic carriers.",1611.05813v2
+2016-11-23,Detection of confined current paths on oxide surfaces by local-conductivity atomic force microscopy with atomic resolution,"The analysis of the electronic surface properties of transition metal oxides
+being key materials for future nanoelectronics requires a direct
+characterization of the conductivity with highest spatial resolution. Using
+local conductivity atomic force microscopy (LC-AFM) we demonstrate the
+possibility of recording current maps with true atomic resolution. The
+application of this technique on surfaces of reduced TiO$_2$ and SrTiO$_3$
+reveals that the distribution of surface conductivity has a significant
+localized nature. Assisted by density functional theory (DFT) we propose that
+the presence of oxygen vacancies in the surface layer of such materials can
+introduce short range disturbances of electronic structure with confinement of
+metallic states on the nanoscale.",1611.07773v1
+2016-12-31,Room temperature single photon emission from oxidized tungsten disulphide multilayers,"Two dimensional systems offer a unique platform to study light matter
+interaction at the nanoscale. In this work we report on robust quantum emitters
+fabricated by thermal oxidation of tungsten disulphide multilayers. The
+emitters show robust, optically stable, linearly polarized luminescence at room
+temperature, can be modeled using a three level system, and exhibit moderate
+bunching. Overall, our results provide important insights into understanding of
+defect formation and quantum emitter activation in 2D materials.",1701.00041v1
+2017-01-06,Fabrication and properties of luminescence polymer composites with erbium/ytterbium oxides and gold nanoparticles,"Rare-earth-doped optical materials are important for light sources in
+optoelectronics, as well as for efficient optical amplification elements and
+other elements of photonics. On the basis of the previously developed method of
+anhydrous, low-temperature synthesis of Er/Yb oxides from their chlorides we
+fabricated proper nanoparticles with defined parameters and used them for the
+development of optically transparent, luminescent polymer nanocomposite with
+low optical scattering, suitable for direct, light-induced formation of
+photonic elements. Introduction of preformed gold nanoparticles in such a
+nanocomposite was also performed and an enhancement of luminescence due to the
+influence of plasmon effects was detected.",1701.01605v1
+2017-01-09,Six-fold crystalline anisotropic magnetoresistance in the (111) LaAlO$_3$/SrTiO$_3$ oxide interface,"We measured the magnetoresistance of the 2D electron liquid formed at the
+(111) LaAlO$_3$/SrTiO$_3$ interface. The hexagonal symmetry of the interface is
+manifested in a six-fold crystalline component appearing in the anisotropic
+magnetoresistance (AMR) and planar Hall data, which agree well with symmetry
+analysis we performed. The six-fold component increases with carrier
+concentration, reaching 15% of the total AMR signal. Our results suggest the
+coupling between higher itinerant electronic bands and the crystal as the
+origin of this effect and demonstrate that the (111) oxide interface is a
+unique hexagonal system with tunable magnetocrystalline effects.",1701.02153v2
+2017-01-10,High performance graphene oxide-based humidity sensor integrated on a photonic crystal cavity,"We report a high performance relative humidity (RH) microsensor by coating a
+few-layer graphene oxide (GO) flake over a photonic crystal (PC) cavity. Since
+the GO layer has a high water-activity and interacts with the evanescent cavity
+mode strongly, the exposure of GO-PC cavity in varied humidity levels results
+in significant resonant wavelength shifts, showing a slope of 0.68 nm/%RH in
+the range of 60%-85% RH. By interrogating the power variation of the cavity
+reflection, the microsensor presents an ultrahigh sensitivity exceeding 3.9
+dB/%RH. Relying on the unimpeded permeation of water molecules through the GO
+interlayers and microscale distribution of the cavity mode, the integrated
+sensor has a response time less than 100 ms, which promises successful
+measurements of human breathing. Combining with the ease of fabrication, this
+high performance RH sensor has potential applications requiring optical access,
+device compactness, and fast dynamic response.",1701.02499v1
+2017-01-17,Conditions for $T^2$ resistivity from electron-electron scattering,"Many complex oxides (including titanates, nickelates and cuprates) show a
+regime in which resistivity follows a power law in temperature ($\rho\propto
+T^2$). By analogy to a similar phenomenon observed in some metals at low
+temperature, this has often been attributed to electron-electron (Baber)
+scattering. We show that Baber scattering results in a $T^2$ power law only
+under several crucial assumptions which may not hold for complex oxides. We
+illustrate this with sodium metal ($\rho_\text{el-el}\propto T^2$) and
+strontium titanate ($\rho_\text{el-el}\not\propto T^2$). We conclude that an
+observation of $\rho\propto T^2$ is not sufficient evidence for
+electron-electron scattering.",1701.04744v1
+2017-01-21,"Plasmonic Doped Semiconductor Nanocrystals: Properties, Fabrication, Applications and Perspectives","Degenerately doped semiconductor nanocrystals (NCs) are of recent interest to
+the NC community due to their tunable localized surface plasmon resonances
+(LSPRs) in the near infrared (NIR). The high level of doping in such materials
+with carrier densities in the range of 1021 cm^-3 leads to degeneracy of the
+doping levels and intense plasmonic absorption in the NIR. The lower carrier
+density in degenerately doped semiconductor NCs compared to noble metals
+enables LSPR tuning over a wide spectral range, since even a minor change of
+the carrier density strongly affects the spectral position of the LSPR. We
+focus on copper chalcogenide NCs and impurity doped metal oxide NCs as the most
+investigated alternatives to noble metals. We shed light on the structural
+changes upon LSPR tuning in vacancy doped copper chalcogenide NCs and deliver a
+picture for the fundamentally different mechanism of LSPR modification of
+impurity doped metal oxide NCs. We review on the peculiar optical properties of
+plasmonic degenerately doped NCs by highlighting the variety of different
+optical measurements and optical modeling approaches. These findings are merged
+in an exhaustive section on new and exciting applications based on the special
+characteristics that plasmonic semiconductor NCs bring along.",1701.05972v1
+2017-01-23,Determination of Hund's coupling in 5d Oxides using Resonant Inelastic X-ray Scattering,"We report resonant inelastic X-ray scattering (RIXS) measurements on ordered
+double perovskite samples containing Re$^{5+}$ and Ir$^{5+}$ with $5d^2$ and
+$5d^4$ electronic configurations respectively. In particular, the observed RIXS
+spectra of Ba$_2$YReO$_6$ and Sr$_2$MIrO$_6$ (M=Y, Gd) show sharp
+intra-t$_{2g}$ transitions, which can be quantitatively understood using a
+minimal `atomic' Hamiltonian incorporating spin-orbit coupling ($\lambda$) and
+Hund's coupling ($J_H$). Our analysis yields $\lambda=0.38(2)$eV with
+$J_H=0.26(2)$eV for Re$^{5+}$, and $\lambda=0.42(2)$eV with $J_H=0.25(4)$eV for
+Ir$^{5+}$. Our results provide the first sharp estimates for the Hund's
+coupling in $5d$ oxides, and suggest that it should be treated on equal footing
+with spin-orbit interaction in multi-orbital $5d$ transition metal compounds.",1701.06584v3
+2017-01-25,Non-conventional porous 12CaO7Al2O3 Transparent Oxide Semiconductor: A Journey from foams to cubes,"In the current study easy method to synthesize C12A7 particles with cubic
+morphology was investigated for the application of Transparent Conducting Oxide
+layer in thinfilm solar cell. By self-combustion method with proper amount of
+urea addition, cubic and foamy structures of C12A7 were achieved at 950 {\deg}C
+and at 510 {\deg}C respectively. Pure C12A7 formation confirmed by P-XRD and
+growth mechanism of the cubes was also understood by SEM and FT-IR analysis.
+Further the band gap was measured 3.07 eV in case of 510 {\deg}C and 3.32 eV in
+case of 950 {\deg}C synthesized particles with the help of UV-Vis analysis.
+During PL single sharp peaks at 399 nm noticed which indicates less defective
+C12A7 at 950 {\deg}C, confirmed by XRD having more crystallinity and less
+strain. No trap state or radiative recombination observed in case of C12A7
+synthesized at 950 {\deg}C sample. Conductivity from conductometry titration
+method was found to be 9.223 mS at 26.3 {\deg}C and 747.33 mS at 26.4 {\deg}C
+for 510 {\deg}C and 950 {\deg}C synthesized samples respectively.",1701.07187v1
+2017-01-31,Dirac nodal lines and induced spin Hall effect in metallic rutile oxides,"We have found Dirac nodal lines (DNLs) in the band structures of metallic
+rutile oxides IrO$_2$, OsO$_2$, and RuO$_2$ and revealed a large spin Hall
+conductivity contributed by these nodal lines, which explains a strong spin
+Hall effect (SHE) of IrO$_2$ discovered recently. Two types of DNLs exist. The
+first type forms DNL networks that extend in the whole Brillouin zone and
+appears only in the absence of spin-orbit coupling (SOC), which induces surface
+states on the boundary. Because of SOC-induced band anti-crossing, a large
+intrinsic SHE can be realized in these compounds. The second type appears at
+the Brillouin zone edges and is stable against SOC because of the protection of
+nonsymmorphic symmetry. Besides reporting new DNL materials, our work reveals
+the general relationship between DNLs and the SHE, indicating a way to apply
+Dirac nodal materials for spintronics.",1701.09089v1
+2017-04-06,Density inhomogeneities and Rashba spin-orbit coupling interplay in oxide interfaces,"There is steadily increasing evidence that the two-dimensional electron gas
+(2DEG) formed at the interface of some insulating oxides like LaAlO3/SrTiO3 and
+LaTiO3/SrTiO3 is strongly inhomogeneous. The inhomogeneous distribution of
+electron density is accompanied by an inhomogeneous distribution of the
+(self-consistent) electric field confining the electrons at the interface. In
+turn this inhomogeneous transverse electric field induces an inhomogeneous
+Rashba spin-orbit coupling (RSOC). After an introductory summary on two
+mechanisms possibly giving rise to an electronic phase separation accounting
+for the above inhomogeneity,we introduce a phenomenological model to describe
+the density-dependent RSOC and its consequences. Besides being itself a
+possible source of inhomogeneity or charge-density waves, the density-dependent
+RSOC gives rise to interesting physical effects like the occurrence of
+inhomogeneous spin-current distributions and inhomogeneous quantum-Hall states
+with chiral ""edge"" states taking place in the bulk of the 2DEG. The
+inhomogeneous RSOC can also be exploited for spintronic devices since it can be
+used to produce a disorder-robust spin Hall effect.",1704.01852v1
+2017-04-25,Perovskite Substrates Boost the Thermopower of Cobaltate Thin Films at High Temperatures,"Transition metal oxides are promising candidates for thermoelectric
+applications, because they are stable at high temperature and because strong
+electronic correlations can generate large Seebeck coefficients, but their
+thermoelectric power factors are limited by the low electrical conductivity. We
+report transport measurements on Ca3Co4O9 films on various perovskite
+substrates and show that reversible incorporation of oxygen into SrTiO3 and
+LaAlO3 substrates activates a parallel conduction channel for p-type carriers,
+greatly enhancing the thermoelectric performance of the film-substrate system
+at temperatures above 450 {\deg}C. Thin-film structures that take advantage of
+both electronic correlations and the high oxygen mobility of transition metal
+oxides thus open up new perspectives for thermopower generation at high
+temperature.",1704.07660v1
+2017-04-25,Observation of Caroli-de Gennes-Matricon Vortex States in YBa$_2$Cu$_3$O$_{7-δ}$,"The copper oxides present the highest superconducting temperature and
+properties at odds with other compounds, suggestive of a fundamentally
+different superconductivity. In particular, the Abrikosov vortices fail to
+exhibit localized states expected and observed in all clean superconductors. We
+have explored the possibility that the elusive vortex-core signatures are
+actually present but weak. Combining local tunneling measurements with
+large-scale theoretical modeling, we positively identify the vortex states in
+YBa$_2$Cu$_3$O$_{7-\delta}$. We explain their spectrum and the observed
+variations thereof from one vortex to the next by considering the effects of
+nearby vortices and disorder in the vortex lattice. We argue that the
+superconductivity of copper oxides is conventional, but the spectroscopic
+signature does not look so because the superconducting carriers are a minority.",1704.07685v2
+2018-05-03,Enhanced Electron Transport in Thin Copper Films via Atomic-Layer Materials Capping,"Using first-principles calculations based on density functional theory and
+non-equilibrium Green's functions, we characterized the effect of surface
+termination on the electronic transport properties of nanoscale Cu slabs. With
+ideal, clean (111) surfaces and oxidized ones as baselines we explore the
+effect of capping the slabs with graphene, hexagonal boron nitrate, molybdenum
+disulfide and stanene. Surface oxide suppresses balistic conductance by a
+factor of 10 compared to the ideal surface. Capping the ideal copper surface
+with graphene slightly increase conductance but MoS$_2$ and stanene have the
+opposite effect due to stronger interactions at the interface. Interestingly,
+we find that capping atomistically roughed copper surfaces with graphene or
+MoS$_2$ decreases the resistance per unit length by 20 and 13%, respectively,
+due to reduced scattering. The results presented in this work suggest that
+two-dimensional materials can be used as an ultra-thin liner in metallic
+interconnect technology without increasing the interconnect line resistivity
+significantly.",1805.01517v1
+2018-05-07,Investigation of the Thermal Stability of the Carbon Framework of Graphene Oxide,"In this study, we use our recently prepared graphene oxide (GO) with an
+almost intact {\sigma}-framework of C-atoms (ai-GO) to probe the thermal
+stability of the carbon framework for the first time. Ai-GO exhibits few
+defects only by preventing CO2 formation during synthesis. Ai-GO was thermally
+treated before chemical reduction and subsequently the resulting defect density
+in graphene was determined by statistical Raman microscopy. Surprisingly, the
+carbon framework of ai-GO is stable in thin films up to 100 {\deg}C.
+Furthermore, we find evidence for an increasing quality of ai-GO upon annealing
+at 50 {\deg}C before reduction. The carbon framework of GO prepared according
+to the popular Hummers method (GO-c)appears to be less stable and decomposition
+starts at 50 {\deg}C what is qualitatively indicated by CO2-trapping
+experiments in {\mu}m-thin films. Information about the stability of GO is
+important for storing, processing and applying GO in applications.",1805.02654v1
+2018-05-08,Surface Sensitive NMR Detection of the SEI Layer on Reduced Graphene Oxide,"The solid electrolyte interphase (SEI) is detrimental for rechargeable
+batteries performance and lifetime. Understanding its formation requires
+analytical techniques that provide molecular level insight. Here dynamic
+nuclear polarization (DNP) is utilized for the first time for enhancing the
+sensitivity of solid state NMR (ssNMR) spectroscopy to the SEI. The approach is
+demonstrated on reduced-graphene oxide (rGO) cycled in Li-ion cells in natural
+abundance and 13C-enriched electrolyte solvents. Our results indicate that DNP
+enhances the signal of outer SEI layers, enabling detection of natural
+abundance 13C spectra from this component of the SEI at reasonable timeframes.
+Furthermore, 13C- enriched electrolytes measurements at 100K provide ample
+sensitivity without DNP due to the vast amount of SEI filling the rGO pores,
+thereby allowing differentiating the inner and outer SEI layers composition.
+Developing this approach further will benefit the study of many electrode
+materials, equipping ssNMR with the needed sensitivity to efficiently probe the
+SEI.",1805.03068v1
+2018-05-04,Highly Integrated Organic-Inorganic Hybrid Architectures by Non-Covalent Exfoliation of Graphite and Assembly with Zinc Oxide Nanoparticles,"Herein, we report an easy, straight forward, and versatile approach to build
+0D/2D hybrid nanoparticle/graphene architectures by means of non-covalent
+chemistry and a modified Layer-by-Layer assembly. Three water soluble perylene
+diimides were employed to efficiently exfoliate pristine graphite into
+positively charged few- and multilayer graphene flakes. Further combination of
+these cationic building blocks with anionic zinc oxide nanoparticles led to the
+formation of tailor-made hybrid films via electrostatic and van der Waals
+interactions. These supramolecular hybrid nano-structures were thoroughly
+characterized by UV/Vis and Raman spectroscopy, AFM as well as electron
+microscopy, showing outstanding long-range homogeneity and high integrity in
+the centimetre-scale, uniform nanometric thickness between 60-100 nm and a
+close contact between the different building blocks. Due to their
+straightforward assembly. These architectures can be considered as promising
+candidates for numerous advanced applications especially in the field of energy
+storage and conversion.",1805.09129v1
+2008-07-02,Graphene Oxidation: Thickness Dependent Etching and Strong Chemical Doping,"Patterned graphene shows substantial potential for applications in future
+molecular-scale integrated electronics. Environmental effects are a critical
+issue in a single layer material where every atom is on the surface. Especially
+intriguing is the variety of rich chemical interactions shown by molecular
+oxygen with aromatic molecules. We find that O2 etching kinetics vary strongly
+with the number of graphene layers in the sample. Three-layer-thick samples
+show etching similar to bulk natural graphite. Single-layer graphene reacts
+faster and shows random etch pits in contrast to natural graphite where
+nucleation occurs at point defects. In addition, basal plane oxygen species
+strongly hole dope graphene, with a Fermi level shift of ~0.5 eV. These oxygen
+species partially desorb in an Ar gas flow, or under irradiation by far UV
+light, and readsorb again in an O2 atmosphere at room temperature. This
+strongly doped graphene is very different than graphene oxide made by mineral
+acid attack.",0807.0261v1
+2008-07-23,Fluorescent oxide nanoparticles adapted to active tips for near-field optics,"We present a new kind of fluorescent oxide nanoparticles with properties well
+suited to active-tip based near-field optics. These particles with an average
+diameter in the range 5-10 nm are produced by Low Energy Cluster Beam
+Deposition (LECBD) from a YAG:Ce3+ target. They are studied by transmission
+electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), classical
+photoluminescence, cathodoluminescence and near-field scanning optical
+microscopy (NSOM). Particles of extreme photo-stability as small as 10 nm in
+size are observed. These emitters are validated as building blocks of active
+NSOM tips by coating a standard optical tip with a 10 nm thick layer of
+YAG:Ce3+ particles directly in the LECBD reactor and by subsequently performing
+NSOM imaging of test surfaces.",0807.3634v2
+2008-07-30,PEGylated Nano-Graphene Oxide for Delivery of Water Insoluble Cancer Drugs,"It is known that many potent, often aromatic drugs are water insoluble, which
+has hampered their use for disease treatment. In this work, we functionalized
+nano-graphene oxide (NGO), a novel graphitic material, with branched
+polyethylene glycol (PEG) to obtain a biocompatible NGO-PEG conjugate stable in
+various biological solutions, and used them for attaching hydrophobic aromatic
+molecules including a camptothecin (CPT) analog, SN38 non-covalently via pi-pi
+stacking. The resulting NGO-PEG-SN38 complex exhibited excellent water
+solubility while maintaining its high cancer cell killing potency similar to
+that of the free SN38 molecules in organic solvents. The efficacy of
+NGO-PEG-SN38 was far higher than that of irinotecan (CPT-11), a FDA approved
+water soluble SN38 prodrug used for the treatment of colon cancer. Our results
+showed that graphene is a novel class of material promising for biological
+applications including future in vivo cancer treatment with various aromatic,
+low-solubility drugs.",0807.4959v1
+2009-12-03,Effects of polarization on the band-structure of delafossite transparent conductive oxides,"We use hybrid functionals and restricted self-consistent GW, state-of-the-art
+theoretical approaches for quasiparticle band structures, to study the
+electronic states of delafossite Cu(Al,In)O$_2$, the first p-type and bipolar
+transparent conductive oxides. We show that self-consistent GW gives remarkably
+wider band gaps than all the other approaches used so far. Accounting for
+polaronic effects in the GW scheme we recover a very nice agreement with
+experiments. Furthermore, the modifications with respect to the Kohn-Sham bands
+are strongly k-dependent, which makes questionable the common practice of using
+a scissor operator. Finally, our results support the view that the low energy
+structures found in optical experiments, and initially attributed to an
+indirect transition, are due to intrinsic defects in the samples.",0912.0618v2
+2009-12-09,"Superconductivity in New Iron Pnictide Oxide (Fe2As2)(Sr4(Mg,Ti)2O6)","We have discovered a new iron pnictide oxide superconductor
+(Fe2As2)(Sr4(Mg,Ti)2O6). This material is isostructual with (Fe2As2)(Sr4M2O6)
+(M = Sc, Cr, V), which were found in previous studies. The structure of this
+compound is tetragonal with a space group of P4/nmm and consists of the
+anti-fluorite type FeAs layer and perovskite-type block layer. The lattice
+constants are a = 3.935 A and c = 15.952 A for (Fe2As2)(Sr4MgTiO6). Bulk
+superconductivity with Tc(onset) of ~26 K was observed for a partially Co
+substituted sample. Moreover, Co-free and Ti-rich samples exhibited higher
+Tc(onset)'s above 35 K, which were further enhanced by applying high pressures
+up to ~43 K.",0912.1840v1
+2009-12-10,Quasiparticle calculations of the electronic properties of ZrO$_2$ and HfO$_2$ polymorphs and their interface with Si,"Quasiparticle calculations are performed to investigate the electronic band
+structures of various polymorphs of Hf and Zr oxides. The corrections with
+respect to density-functional-theory results are found to depend only weakly on
+the crystal structure. Based on these bulk calculations as well as those for
+bulk Si, the effect of quasiparticle corrections is also investigated for the
+band offsets at the interface between these oxides and Si assuming that the
+lineup of the potential at the interface is reproduced correctly within
+density-functional theory. On the one hand, the valence band offsets are
+practically unchanged with a correction of a few tenths of eV. On the other
+hand, conduction band offsets are raised by 1.3--1.5 eV. When applied to
+existing calculations for the offsets at the density-functional-theory level,
+our quasiparticle corrections provide results in good agreement with the
+experiment.",0912.1977v1
+2009-12-14,Visualizing Graphene Based Sheets by Fluorescence Quenching Microscopy,"Graphene based sheets have stimulated great interest due to their superior
+mechanical, electrical and thermal properties. A general visualization method
+that allows quick observation of these single atomic layers would be highly
+desirable as it can greatly facilitate sample evaluation and manipulation, and
+provide immediate feedback to improve synthesis and processing strategies. Here
+we report that graphene based sheets can be made highly visible under a
+fluorescence microscope by quenching the emission from a dye coating, which can
+be conveniently removed afterwards by rinsing without disrupting the sheets.
+Current imaging techniques for graphene based sheets rely on the use of special
+substrates. In contrast, the fluorescence quenching mechanism is no longer
+limited by the types of substrates. Graphene, reduced graphene oxide, or even
+graphene oxide sheets deposited on arbitrary substrates can now be readily
+visualized by eye with good contrast for layer counting. Direct observation of
+suspended sheets in solution was also demonstrated. The fluorescence quenching
+microscopy offers unprecedented imaging flexibility and could become a general
+tool for characterizing graphene based materials.",0912.2675v1
+2011-10-31,Direct Observation of an Interface Dipole between Two Metallic Oxides Caused by Localized Oxygen Vacancies,"Oxygen vacancies are increasingly recognized to play a role in phenomena
+observed at transition-metal oxide interfaces. Here we report a study of
+SrRuO3/La0.7Sr0.3MnO3 (SRO/LSMO) interfaces using a combination of quantitative
+aberration-corrected scanning transmission electron microscopy, electron energy
+loss spectroscopy, and density-functional calculations. Cation displacements
+are observed at the interface, indicative of a dipole-like electric field even
+though both materials are nominally metallic. The observed displacements are
+reproduced by theory if O vacancies are present in the near-interface LSMO
+layers. The results suggest that atomic-scale structural mapping can serve as a
+quantitative indicator of the presence of O vacancies at interfaces.",1111.0023v1
+2011-11-07,"Carbon States in Carbon-Encapsulated Nickel Nanoparticles Studied by Means of X-Ray Absorption, Emission, and Photoelectron Spectroscopies","Electronic structure of nickel nanoparticles encapsulated in carbon was
+characterized by photoelectron, X-ray absorption, and X-ray emission
+spectroscopies. Experimental spectra are compared with the density of states
+calculated in the frame of the density functional theory. The carbon shell of
+Ni nanoparticles has been found to be multilayer graphene with significant
+(about 6%) amount of Stone--Wales defects. Results of the experiments evidence
+protection of the metallic nanoparticles from the environmental degradation by
+providing a barrier against oxidation at least for two years. Exposure in air
+for 2 years leads to oxidation only of the carbon shell of Ni@C nanoparticles
+with coverage of functional groups.",1111.1470v1
+2011-11-09,Ab initio calculation of d-d excitations in quasi-one-dimensional Cu d9 correlated materials,"With wavefunction-based electronic-structure calculations we determine the Cu
+d-d excitation energies in quasi-one-dimensional spin-chain and ladder copper
+oxides. A complete set of local excitations has been calculated for cuprates
+with corner-sharing (Sr2CuO3 and SrCuO2) and edge-sharing (LiVCuO4, CuGeO3,
+LiCu2O2 and Li2CuO2) CuO4 plaquettes, with corner-sharing CuF6 octahedra
+(KCuF3), for the ladder system CaCu2O3, and for multiferroic cupric oxide CuO.
+Our data compare well with available results of optical absorption measurements
+on KCuF3 and the excitation energies found by resonant inelastic x-ray
+scattering experiments for CuO. The ab initio results we report for the other
+materials should be helpful for the interpretation of future resonant inelastic
+x-ray scattering experiments on those highly anisotropic compounds.",1111.2231v1
+2011-11-14,Ultrafast strain engineering in complex oxide heterostructures,"We report on ultrafast optical experiments in which femtosecond mid-infrared
+radiation is used to excite the lattice of complex oxide heterostructures. By
+tuning the excitation energy to a vibrational mode of the substrate, a
+long-lived five-order-of-magnitude increase of the electrical conductivity of
+NdNiO3 epitaxial thin films is observed as a structural distortion propagates
+across the interface. Vibrational excitation, extended here to a wide class of
+heterostructures and interfaces, may be conducive to new strategies for
+electronic phase control at THz repetition rates.",1111.3155v1
+2011-11-16,Dimensionality Control of Electronic Phase Transitions in Nickel-Oxide Superlattices,"The competition between collective quantum phases in materials with strongly
+correlated electrons depends sensitively on the dimensionality of the electron
+system, which is difficult to control by standard solid-state chemistry. We
+have fabricated superlattices of the paramagnetic metal LaNiO3 and the wide-gap
+insulator LaAlO3 with atomically precise layer sequences. Using optical
+ellipsometry and low-energy muon spin rotation, superlattices with LaNiO3 as
+thin as two unit cells are shown to undergo a sequence of collective
+metalinsulator and antiferromagnetic transitions as a function of decreasing
+temperature, whereas samples with thicker LaNiO3 layers remain metallic and
+paramagnetic at all temperatures. Metal-oxide superlattices thus allow control
+of the dimensionality and collective phase behavior of correlated-electron
+systems.",1111.3819v1
+2011-12-31,Modeling of biological doses and mechanical effects on bone transduction,"Shear stress, hormones like parathyroid and mineral elements like calcium
+mediate the amplitude of stimulus signal which affects the rate of bone
+remodeling. The current study investigates the theoretical effects of different
+metabolic doses in stimulus signal level on bone. The model was built
+considering the osteocyte as the sensing center mediated by coupled mechanical
+shear stress and some biological factors. The proposed enhanced model was
+developed based on previously published works dealing with different aspects of
+bone transduction. It describes the effects of physiological doses variations
+of Calcium, Parathyroid Hormone, Nitric Oxide and Prostaglandin E2 on the
+stimulus level sensed by osteocytes in response to applied shear stress
+generated by interstitial fluid flow. We retained the metabolic factors
+(Parathyroid Hormone, Nitric Oxide, and Prostaglandin E2) as parameters of bone
+cell mechanosensitivity because stimulation/inhibition of induced pathways
+stimulates osteogenic response in vivo. We then tested the model response in
+term of stimulus signal variation versus the biological factors doses to
+external mechanical stimuli. Despite the limitations of the model, it is
+consistent and has physiological bases. Biological inputs are histologically
+measurable. This makes the model amenable to experimental verification.",1201.0239v1
+2012-01-10,Adsorption and dissociation of H$_{2}$O monomer on ceria(111): Density functional theory calculations,"The adsorption properties of isolated H$_{2}$O molecule on stoichiometric and
+reduced (with on-surface oxygen vacancy) ceria(1111) surfaces at low coverage
+are theoretically investigated by using density-functional-theory+\emph{U}
+calculations and \textit{ab initio} molecular dynamics simulations. We identify
+the most stable adsorption configurations on these two kinds of surfaces, which
+form two hydrogen bonds between the water molecule and the oxide surface. The
+electronic structures indicate that the hybridization of the molecular orbitals
+of water and surface-layer O-2\emph{p} states dominates the interactions
+between adsorbate and substrate. The barrier of 0.51 eV for water diffusion on
+the stoichiometric surface implies the inertia of water unless up to a high
+temperature of 600 K, which is confirmed by the molecular dynamics simulations.
+For the reduced surface, we find that the oxygen vacancy obviously enhances the
+interaction. Moreover, it is facilitated for water to dissociate into H and OH
+species with a hydroxyl surface formed, instead of oxidizing the reduced
+surface with the production of hydrogen gas. In addition, the molecular
+dynamics simulations at low temperature 100 K confirm the dissociation process.",1201.1974v2
+2012-01-23,"Simulation study of a highly efficient, high resolution X-ry sensor based on self-organizing aluminum oxide","State of the art X-ray imaging sensors comprise a trade-off between the
+achievable efficiency and the spatial resolution. To overcome such limitations,
+the use of structured and scintillator filled aluminum oxide (AlOx) matrices
+has been investigated. We used Monte-Carlo (MC) X-ray simulations to determine
+the X-ray imaging quality of these AlOx matrices. Important factors which
+influence the behavior of the matrices are: filling factor (surface ratio
+between channels and 'closed' AlOx), channel diameter, aspect ratio, filling
+material etc. Therefore we modeled the porous AlOx matrix in several different
+ways with the MC X-ray simulation tool ROSI [1] and evaluated its properties to
+investigate the achievable performance at different X-ray spectra, with
+different filling materials (i.e. scintillators) and varying channel height and
+pixel readout. In this paper we focus on the quantum efficiency, the spatial
+resolution and image homogeneity.",1201.4660v1
+2012-01-28,Topological Quantum Phase Transition in 5$d$ Transition Metal Oxide Na$_2$IrO$_3$,"We predict a quantum phase transition from normal to topological insulators
+in the 5$d$ transition metal oxide Na$_2$IrO$_3$, where the transition can be
+driven by the change of the long-range hopping and trigonal crystal field
+terms. From the first-principles-derived tight-binding Hamiltonian we determine
+the phase boundary through the parity analysis. In addition, our
+first-principles calculations for Na$_2$IrO$_3$ model structures show that the
+interlayer distance can be an important parameter for the existence of a
+three-dimensional strong topological insulator phase. Na$_2$IrO$_3$ is
+suggested to be a candidate material which can have both a nontrivial topology
+of bands and strong electron correlations.",1201.5929v2
+2012-04-27,Structural recovery of ion implanted ZnO nanowires,"Ion implantation is an interesting method to dope semiconducting materials
+such as zinc oxide provided that the implantation-induced defects can be
+subsequently removed. Nitrogen implantation followed by anneals under O2 were
+carried out on zinc oxide nanowires in the same conditions as in a previous
+study on bulk ZnO [J. Appl.Phys. 109, 023513 (2011)], allowing a direct
+comparison of the defect recovery mechanisms. Transmission electron microscopy
+and cathodoluminescence were carried out to assess the effects of nitrogen
+implantation and of subsequent anneals on the structural and optical properties
+of ZnO nanowires. Defect recovery is shown to be more effective in nanowires
+compared with bulk material due to the proximity of free surfaces.
+Nevertheless, the optical emission of implanted and annealed nanowires
+deteriorated compared to as-grown nanowires, as also observed for unimplanted
+and annealed nanowires. This is tentatively attributed to the dissociation of
+excitons in the space charge region induced by O2 adsorption on the nanowire
+surface.",1204.6138v1
+2012-04-29,Exponential decay of equal-time four-point correlation functions in the Hubbard model on the copper-oxide lattice,"For the Hubbard model on the two-dimensional copper-oxide lattice, equal-time
+four-point correlation functions at positive temperature are proved to decay
+exponentially in the thermodynamic limit if the magnitude of the on-site
+interactions is smaller than some power of temperature. This result especially
+implies that the equal-time correlation functions for singlet Cooper pairs of
+various symmetries decay exponentially in the distance between the Cooper pairs
+in high temperatures or in low-temperature weak-coupling regimes. The proof is
+based on a multi-scale integration over the Matsubara frequency.",1204.6470v3
+2013-09-18,Pseudosymmetric bias and correct estimation of Coulomb/confinement energy for unintentional quantum dot in channel of metal-oxide-semiconductor field-effect transistor,"We describe a measurement method that enables the correct estimation of the
+charging energy of an unintentional quantum dot (QD) in the channel of a
+metal-oxide-semiconductor field-effect transistor (MOSFET). If the channel has
+a dominant QD with a large charging energy and an array of stray QDs with much
+weaker charging, this method eliminates the additional voltage drops due to
+stray QDs by regarding the stray QDs as series resistors. We apply this method
+to a short-channel MOSFET and find that the charging energy of the dominant QD
+can indeed be smaller than the size of the Coulomb diamond.",1309.4525v1
+2013-09-19,Near-Field Optical Effect of a Core-Shell Nanostructure In Proximity to a Flat Surface,"We provide an analytical solution to study the near field optical effect of a
+core-shell nanostructure in proximity to a flat surface, within quasi-static
+approximation. The distribution of electrostatic potential and field
+enhancement in this complex geometry are obtained by solving a set of linear
+equations. This analytical result can be applied to a wide range of systems
+associated with near field optics and surface plasmon polaritons. As an
+illustration of the power of this technique, we study the field attenuation
+effect of oxidized shell in a silver tip in near field scanning microscope. The
+thickness of oxidized layer can be monitored by measuring the light intensity.
+In addition, we propose a novel method to detect local temperature with spatial
+resolution down to nm scale, based on a Ag-Au core-shell structure.",1309.5104v1
+2013-09-20,CHx adsorption (x=1-4) and thermodynamic stability on CeO2(111) surface: A first-principles investigation,"We present an ab initio investigation of the interaction between methane, its
+dehydrogenated forms and the cerium oxide surface. In particular, the
+stoichiometric CeO2(111) surface and the one with oxygen vacancies are
+considered. We study the geometries, energetics and electronic structures of
+various configurations of these molecules adsorbed on the surface in vacuum,
+and we extend the analysis to realistic environmental conditions. A phase
+diagram of the adsorbate-surface system is constructed and relevant transition
+phases are analyzed in detail, showing the conditions where partial oxidation
+of methane can occur.",1309.5177v4
+2014-05-05,"A model for the catalytic oxidation of CO that includes CO desorption and diffusion, O repulsion, and impurities in the gas phase","We present kinetic Monte Carlo simulations exploring the nonequilibrium phase
+diagram of a modified Ziff-Gulari-Barshad (ZGB) dynamic lattice-gas model for
+the catalytic oxidation of carbon monoxide (CO) on a surface. The modified
+model includes the simultaneous presence of contaminants in the gas phase, CO
+desorption, CO diffusion, and strong repulsion between adsorbed oxygen (O)
+atoms; all of which have been observed in experimental systems. We find that
+the strong O-O repulsion produces higher reaction rates, albeit in a reduced
+reactive pressure window. In systems with impurities, the CO$_2$ production
+rate is greatly reduced, but this effect is mitigated by CO desorption and
+diffusion. CO desorption has the effect of widening the reactive pressure
+window, while CO diffusion has the effect of increasing the reaction rate. In
+some parameter regimes the presence of impurities destroys the discontinuous
+transition between the reactive and high CO coverage phases.",1405.0948v2
+2014-05-09,The role of random electric fields in relaxors,"PbZr_{1-x}Ti_xO_3 (PZT) and Pb(Mg_{1/3}Nb_{2/3})_{1-x}Ti_xO_3 (PMN-$x$PT) are
+complex lead-oxide perovskites that display exceptional piezoelectric
+properties for pseudorhombohedral compositions near a tetragonal phase
+boundary. In PZT these compositions are ferroelectrics, but in PMN-xPT they are
+relaxors because the dielectric permittivity is frequency dependent and
+exhibits non-Arrhenius behavior. We show that the nanoscale structure unique to
+PMN-xPT and other lead-oxide perovskite relaxors is absent in PZT and
+correlates with a greater than 100% enhancement of the longitudinal
+piezoelectric coefficient in PMN-xPT relative to that in PZT. By comparing
+dielectric, structural, lattice dynamical, and piezoelectric measurements on
+PZT and PMN-xPT, two nearly identical compounds that represent weak and strong
+random electric field limits, we show that quenched (static) random fields
+establish the relaxor phase and identify the order parameter.",1405.2306v1
+2014-05-15,On the calculation of crystal field parameters using Wannier functions,"We discuss the calculation of crystal field splittings using Wannier
+functions and show how the ligand field contributions can be separated from the
+bare Coulomb contribution to the crystal field by constructing sets of Wannier
+functions incorporating different levels of hybridization. We demonstrate this
+method using SrVO$_3$ as a generic example of a transition metal oxide. We then
+calculate trends in the crystal field splitting for two series of hypothetical
+tetragonally distorted perovskite oxides and discuss the relation between the
+calculated ""electro-static"" contribution to the crystal field and the simple
+point charge model. Finally, we apply our method to the charge
+disproportionated 5$d$ electron system CsAuCl$_3$. We show that the negative
+charge transfer energy in this material leads to a reversal of the $p$-$d$
+ligand contribution to the crystal field splitting such that the $e_g$ states
+of the nominally Au$^{3+}$ cation are energetically lower than the
+corresponding $t_{2g}$ states.",1405.3804v1
+2014-05-17,High-performance bilayer metal-oxide thin film transistors using ultra-thin solution-processed ZrOx dielectric,"We reported here a high-performance In2O3/InZnO bilayer metal-oxide (BMO)
+thin-film transistor (TFT) using ultra-thin solution-processed ZrOx dielectric.
+A thin layer of In2O3 offers a higher carrier concentration, thereby maximizing
+the charge accumulation and yielding high carrier mobility. A thick layer of
+InZnO controls the charge conductance resulting in low off-state current and
+suitable threshold voltage. As a consequence, the BMO TFT showed higher
+filed-effect mobility (37.9 cm2/V s) than single-layer InZnO TFT (7.6 cm2/V s).
+More importantly, an on/off current ratio of 109, a subthreshold swing voltage
+of 120 mV/decade, as well as a threshold voltage shift (less than 0.4 V) under
+bias stress for 2.5 hours were obtained simultaneously. These promising
+properties are obtained at a low operation voltage of 3 V. This work
+demonstrates that the BMO TFT has great potential applications as switching
+transistor and low-power devices.",1405.4373v2
+2014-06-06,Probing the Electrical Properties of Overlapped Graphene Grain Boundaries by Raman spectroscopy,"The effect of grain boundaries and wrinkles on the electrical properties of
+polycrystalline graphene is pronounced. Here we investigate the stitching
+between grains of polycrystalline graphene, specifically, overlapping of layers
+at the boundaries, grown by chemical vapor deposition (CVD) and subsequently
+doped by the oxidized Cu substrate. We analyze overlapped regions between 60
+and 220 nm wide via Raman spectroscopy, and find that some of these overlapped
+boundaries contain AB stacked bilayers. The Raman spectra from the overlapped
+grain boundaries are distinctly different from bilayer graphene and exhibit
+splitting of the G band peak. The degree of splitting, peak widths, as well as
+peak intensities depend on the width of the overlap. We attribute these
+features to inhomogeneous doping by charge carriers (holes) across the
+overlapped regions via the oxidized Cu substrate. As a result, the Fermi level
+at the overlapped grain boundaries lies between 0.3 and 0.4 eV below the charge
+neutrality point. Our results suggest an enhancement of electrical conductivity
+across overlapped grain boundaries, similar to previously observed
+measurements(1). The dependence of charge distribution on the width of
+overlapping of grain boundaries may have strong implications for the growth of
+large-area graphene with enhanced conductivity.",1406.1555v1
+2014-06-18,Photoionization cross section of 1s orthoexcitons in cuprous oxide,"We report measurements of the attenuation of a beam of
+orthoexciton-polaritons by a photoionizing optical probe. Excitons were
+prepared in a narrow resonance by two photon absorption of a 1.016 eV, 54 ps
+pulsed light source in cuprous oxide (Cu2O) at 1.4 K. A collinear, 1.165 eV, 54
+ps probe delayed by 119 ps was used to measure the photoionization cross
+section of the excitons. Two photon absorption is quadratic with respect to the
+intensity of the pump and leads to polariton formation. Ionization is linear
+with respect to the intensity of the probe. Subsequent carrier recombination is
+quadratic with respect to the intenisty of the probe, and is distinguished
+because it shifts the exciton momentum away from the polariton anticrossing;
+the photoionizing probe leads to a rise in phonon-linked luminescence in
+addition to the attenuation of polaritons. The evolution of the exciton density
+was determined by variably delaying the probe pulse. Using the probe irradiance
+and the reduction in the transmitted polariton light, a cross section of
+3.9*10^(-22) m^2 was deduced for the probe frequency.",1406.4911v1
+2014-06-25,Electron Glass in a three-dimensional system,"We report on non-equilibrium transport features observed in experiments using
+three-dimensional amorphous indium-oxide films. It is demonstrated that all the
+features that characterize intrinsic electron-glasses which heretofore were
+seen in two-dimensional samples are also observed in field-effect measurements
+of systems that exhibit three-dimensional variable-range-hopping. In
+particular, a memory-dip is observed in samples configured with gate. The
+memory-dip width and magnitude support models that associate the phenomenon
+with the Coulomb-gap. The memory-dip and the glassy effects disappear once the
+quenched disorder in the system is reduced and the system becomes diffusive.
+This happens when the Ioffe-Regel dimensional parameter k_{F}l exceeds 0.3
+which is the critical value for the metal-to-insulator transition in all
+versions of the amorphous indium-oxides [Phys. Rev. B 86, 165101 (2012)]. This
+confirms that being in the Anderson localized phase is a pre-requisite for
+observing the memory-dip and the associated glassy effects. The results of the
+gating experiments suggest that the out-of equilibrium effect caused by
+inserted charge extend over spatial scales considerably larger than the
+screening length.",1406.6455v2
+2014-06-27,Competition between covalent bonding and charge transfer at complex-oxide interfaces,"Here we study the electronic properties of cuprate/manganite interfaces. By
+means of atomic resolution electron microscopy and spectroscopy, we produce a
+subnanometer scale map of the transition metal oxidation state profile across
+the interface between the high $T_c$ superconductor YBa$_2$Cu$_3$O$_{7-\delta}$
+and the colossal magnetoresistance compound (La,Ca)MnO$_3$. A net transfer of
+electrons from manganite to cuprate with a peculiar non-monotonic charge
+profile is observed. Model calculations rationalize the profile in terms of the
+competition between standard charge transfer tendencies (due to band mismatch),
+strong chemical bonding effects across the interface, and Cu substitution into
+the Mn lattice, with different characteristic length scales.",1406.7323v1
+2015-12-02,A machine learning-based selective sampling procedure for identifying the low energy region in a potential energy surface: a case study on proton conduction in oxides,"In this paper, we propose a selective sampling procedure to preferentially
+evaluate a potential energy surface (PES) in a part of the configuration space
+governing a physical property of interest. The proposed sampling procedure is
+based on a machine learning method called the Gaussian process (GP), which is
+used to construct a statistical model of the PES for identifying the region of
+interest in the configuration space. We demonstrate the efficacy of the
+proposed procedure for atomic diffusion and ionic conduction, specifically the
+proton conduction in a well-studied proton-conducting oxide, barium zirconate
+BaZrO3. The results of the demonstration study indicate that our procedure can
+efficiently identify the low-energy region characterizing the proton conduction
+in the host crystal lattice, and that the descriptors used for the statistical
+PES model have a great influence on the performance.",1512.00623v2
+2015-12-25,Photoluminescence from Silicon nanoparticles embedded in ammonium silicon hexafluoride,"Silicon (Si) nanoparticles (NPs) were synthesized by transforming Si wafer
+surface to ammonium silicon hexafluoride (ASH) or (NH4)2SiF6 under acid vapor
+treatment. Si-NPs are embedded within the polycrystalline (ASH) layer formed on
+the Si surface exhibit a strong green-orange photoluminescence (PL). Difference
+measurements revealed a major double component spectra consisting of a broad
+band associated with the ASH-Si wafer interfacial porous oxide layer and a high
+energy band attributable to Si-NPs embedded in the ASH. The origin of the
+latter emission can be explained in terms of quantum/spatial confinement
+effects probably mediated by oxygen related defects in or around Si-NPs.
+Although Si-NPs are derived from the interface they are much smaller in size
+than those embedded within the interfacial porous oxide layer (SiOx, 1 < x <
+2). Transmission electron microscopy (TEM) combined with Raman scattering and
+Fourier transformed infrared (FTIR) analysis confirmed the presence of Si-NPs
+and Si-O bondings pointing to the role of oxygen related defects. The presence
+of oxygen of up to 4.5 at.% in the (NH4)2SiF6 layer was confirmed by energy
+dispersive spectroscopy (EDS) analysis.",1512.07991v1
+2015-12-21,Modulation of diffusion rate of therapeutic peptide drugs using graphene oxide membranes,"We investigate diffusion of a peptide drug through Graphene Oxide (GO)
+membranes that are modeled as a porous layered laminate constructed from
+aligned flakes of GO. Our experiments using a peptide drug show a tunable
+non-linear dependence of the peptide concentration upon time. This is confirmed
+using numerical simulations with a diffusion equation accounting for the
+photothermal degradation of fluorophores and an effective percolation model.
+This modeling yields an interpretation of the control and delay of drug
+diffusion through GO membranes. The ability to modulate the density of
+hydrogel-like GO membranes to control drug release rates could be a step
+forwards in tailoring drug release properties of the hydrogels for therapeutic
+applications.",1512.08506v1
+2015-12-29,$π$-bonding-dominated energy gaps in graphene oxides,"Chemical bondings of graphene oxides with oxygen concentration from 1\% to
+50\% are investigated using first-principle calculations. Energy gaps are
+mainly determined by the competition of orbital hybridizations in C-C, O-O, and
+C-O bonds. They are very sensitive to the changes in oxygen concentration and
+distributions. There exists five types of $\pi$ bondings during the variation
+from the full to vanishing adsorptions, namely the complete termination, the
+partial suppression, the 1D bonding, the deformed planar bonding, and the
+well-behaved one. They can account for the finite and gapless characteristics,
+corresponding to the O-concentrations of $>$25\% and $<$3\%, respectively. The
+feature-rich chemical bondings dominate band structures and density of states,
+leading to diverse electronic properties.",1512.08693v1
+2016-05-04,Atomically Thin Boron Nitride: Unique Properties and Applications,"Atomically thin boron nitride (BN) is an important two-dimensional (2D)
+nanomaterial, with many properties distinct from graphene. In this feature
+article, these unique properties and associated applications often not possible
+from graphene are outlined. The article starts with characterization and
+identification of atomically thin BN. It is followed by demonstrating their
+strong oxidation resistance at high temperatures and applications in protecting
+metals from oxidation and corrosion. As flat insulators, BN nanosheets are
+ideal dielectric substrates for surface enhanced Raman spectroscopy (SERS) and
+electronic devices based on 2D heterostructures. The light emission of BN
+nanosheets in the deep ultraviolet (DUV) and ultraviolet (UV) regions are also
+included for its scientific and technological importance. The last part is
+dedicated to synthesis, characterization, and optical properties of BN
+nanoribbons, a special form of nanosheets.",1605.01136v1
+2016-05-08,Scanning tunneling spectroscopy of superconductivity on surfaces of LiTi2O4(111) thin films,"Unique superconductivity at surfaces/interfaces, as exemplified by
+LaAlO3/SrTiO3 interfaces, and the high transition temperature in ultrathin FeSe
+films, have triggered intense debates on how superconductivity is affected in
+atomic and electronic reconstructions. The surface of superconducting cubic
+spinel oxide LiTi2O4 is another interesting system because its inherent surface
+electronic and atomic reconstructions add complexity to superconducting
+properties. Investigations of such surfaces are hampered by the lack of single
+crystals or high-quality thin films. Here, using low-temperature scanning
+tunneling microscopy, we report an unexpected small superconducting energy gap
+and a long coherence length on the surface of LiTi2O4 (111) epitaxial thin
+films. Furthermore, we find that a pseudogap opening at the Fermi energy
+modifies the surface superconductivity. Our results open an avenue, exploring
+anomalous superconductivity on the surface of cubic transition-metal oxides
+where the electronic states are spontaneously modulated with involving rich
+many-body interactions.",1605.02327v2
+2016-05-09,"Interplay between strain, defect charge state and functionality in complex oxides","We use first-principles calculations to investigate the interplay between
+strain and the charge state of point defect impurities in complex oxides. Our
+work is motivated by recent interest in using defects as active elements to
+provide novel functionality in coherent epitaxial films. Using oxygen vacancies
+as model point defects, and CaMnO$_3$ and MnO as model materials, we calculate
+the changes in internal strain caused by changing the charge state of the
+vacancies, and conversely the effect of strain on charge-state stability. Our
+results show that the charge state is a degree of freedom that can be used to
+control the interaction of defects with strain and hence the concentration and
+location of defects in epitaxial films. We propose the use of field-effect
+gating to reversibly change the charge state of defects and hence the internal
+strain and corresponding strain-induced functionalities.",1605.02462v1
+2016-08-01,Interferometric Motion Detection in Atomic Layer 2D Nanostructures: Visualizing Signal Transduction Efficiency and Optimization Pathways,"Atomic layer crystals are emerging building blocks for enabling new
+two-dimensional (2D) nanomechanical systems, whose motions can be coupled to
+other attractive physical properties in such 2D systems. Optical interferometry
+has been very effective in reading out the infinitesimal motions of these 2D
+structures and spatially resolving different modes. To quantitatively
+understand the detection efficiency and its dependence on the device parameters
+and interferometric conditions, here we present a systematic study of the
+intrinsic motion responsivity in 2D nanomechanical systems using a
+Fresnel-law-based model. We find that in monolayer to 14-layer structures, MoS2
+offers the highest responsivity among graphene, h-BN, and MoS2 devices and for
+the three commonly used visible laser wavelengths (633, 532, and 405nm). We
+also find that the vacuum gap resulting from the widely used 300nm-oxide
+substrate in making 2D devices, fortunately, leads to close-to-optimal
+responsivity for a wide range of 2D flakes. Our results elucidate and
+graphically visualize the dependence of motion transduction responsivity upon
+2D material type and number of layers, vacuum gap, oxide thickness, and
+detecting wavelength, thus providing design guidelines for constructing 2D
+nanomechanical systems with optimal optical motion readout.",1608.00377v1
+2016-08-03,Overall thermomechanical properties of layered materials for energy devices applications,"This paper is concerned with the analysis of effective thermomechanical
+properties of multi- layered materials of interest for solid oxide fuel cells
+(SOFC) and lithium ions batteries fabrication. The recently developed
+asymptotic homogenization procedure is applied in order to express the overall
+thermoelastic constants of the first order equivalent continuum in terms of
+microfluctuations functions, and these functions are obtained by the solution
+of the corresponding recursive cell problems. The effects of thermal stresses
+on periodic multi-layered thermoelastic composite reproducing the
+characteristics of solid oxide fuel cells (SOFC-like) are studied assuming
+periodic body forces and heat sources, and the solution derived by means of the
+asymptotic homogenization approach is compared with the results obtained by
+finite elements analysis of the associate heterogeneous material.",1608.01078v1
+2016-08-06,Extended friction elucidates the breakdown of fast water transport in graphene oxide membranes,"The understanding of water transport in graphene oxide (GO) membranes stands
+out as a major theoretical problem in graphene research. Notwithstanding the
+intense efforts devoted to the subject in the recent years, a consolidated
+picture of water transport in GO membranes is yet to emerge. By performing
+mesoscale simulations of water transport in ultrathin GO membranes, we show
+that even small amounts of oxygen functionalities can lead to a dramatic drop
+of the GO permeability, in line with experimental findings. The coexistence of
+bulk viscous dissipation and spatially extended molecular friction results in a
+major decrease of both slip and bulk flow, thereby suppressing the fast water
+transport regime observed in pristine graphene nanochannels. Inspection of the
+flow structure reveals an inverted curvature in the near-wall region, which
+connects smoothly with a parabolic profile in the bulk region. Such inverted
+curvature is a distinctive signature of the coexistence between single-particle
+Langevin friction and collective hydrodynamics. The present mesoscopic model
+with spatially extended friction may offer a computationally efficient tool for
+future simulations of water transport in nanomaterials.",1608.02098v1
+2016-08-11,Evolution of Insulator-Metal Phase Transitions in Epitaxial Tungsten Oxide Films during Electrolyte-Gating,"An interface between an oxide and an electrolyte gives rise to various
+processes as exemplified by electrostatic charge accumulation/depletion and
+electrochemical reactions such as intercalation/decalation under electric
+field. Here we directly compare typical device operations of those in electric
+double layer transistor geometry by adopting ${A}$-site vacant perovskite
+WO$_3$ epitaxial thin films as a channel material and two different
+electrolytes as gating agent. $\textit{In situ}$ measurements of x-ray
+diffraction and channel resistance performed during the gating revealed that in
+both the cases WO$_3$ thin film reaches a new metallic state through multiple
+phase transitions, accompanied by the change in out-of-plane lattice constant.
+Electrons are electrostatically accumulated from the interface side with an
+ionic liquid, while alkaline metal ions are more uniformly intercalated into
+the film with a polymer electrolyte. We systematically demonstrate this
+difference in the electrostatic and electrochemical processes, by comparing
+doped carrier density, lattice deformation behavior, and time constant of the
+phase transitions.",1608.03357v1
+2016-08-11,Orbital and spin order in oxide two-dimensional electron gases,"We describe a variational theory of multi-band two-dimensional electron gases
+that captures the interplay between electrostatic confining potentials,
+orbital-dependent interlayer electronic hopping and electron-electron
+interactions, and apply it to the d-band two-dimensional electron gases that
+form near perovskite oxide surfaces and heterojunctions. These multi-band
+two-dimensional electron gases are prone to the formation of
+Coulomb-interaction-driven orbitally-ordered nematic ground-states. We find
+that as the electron density is lowered and interaction effects strengthen,
+spontaneous orbital order occurs first, followed by spin order. We compare our
+results with known properties of single-component two-dimensional electron gas
+systems and comment on closely related physics in semiconductor quantum wells
+and van der Waals heterostructures.",1608.03625v1
+2016-08-18,A Simulation Study on the Feasibility of Radio Enhancement Therapy with Calcium Tungstate and Hafnium Oxide Nanoparticles,"Herein is a simulation study on the radio enhancement potential of calcium
+tungstate (CaWO4) and hafnium oxide (HfO2) nanoparticles (NPs) relative to gold
+(Au) NPs. The work utilizes the extensively studied Au NP as the ""gold
+standard"" to which the novel materials can be compared. All three materials
+were investigated in-silico with the software Penetration and Energy Loss of
+Positrons and Electrons (PENELOPE) developed by Francesc Salvat and distributed
+in the United States by the Radiation Safety Information Computational Center
+(RSICC) at Oak Ridge National Laboratory. The aims are: (1) Do CaWO4 and HfO2
+NPs function like Au?, and (2) if not, how else might they function to enhance
+radio therapy? Our investigations have found that HfO2 likely functions as Au,
+but not as effectively. CaWO4 likely does not function as Au, and we propose
+that CaWO4 may exhibit cancer killing traits through its intrinsic UV
+luminescence property.",1608.05302v1
+2016-08-30,Doping-Induced Alterations in Electronic Structure of Copper Oxide Superconductors and a New Horizon for Higher Tc materials,"By paying special attention to the fact that the doped holes induce
+deformation of CuO6 octahedrons (or CuO5 pyramids) in cuprate superconductors,
+we develop a non-rigid band theory treating doping-induced alterations of
+energy-band structures in copper oxide superconductors. Thanks to this theory,
+we obtain a complete picture of the doping-induced alteration in the electronic
+structure of La2CuO4, from the spin-disordered insulating phase to the metallic
+phase. We conclude that the Fermi surface structure of this cuprate in the
+underdoped region consists of Fermi pockets in the antinodal region and Fermi
+arcs in the nodal region, and thus that the origin of a so-called pseudogap is
+closely related to the existence of Fermi pockets. Moreover, we show that the
+carriers on the Fermi pockets contribute to the phonon mechanism in d-wave
+superconductivity. Finally, we discuss how one will be able to find higher Tc
+materials, based on the conclusions mentioned above.",1608.08338v2
+2016-12-04,Conducting interface in oxide homojunction: understanding of superior properties in black TiO2,"Black TiO2 nanoparticles with a crystalline-core and amorphous-shell
+structure exhibit superior optoelectronic properties in comparison with
+pristine TiO2. The fundamental mechanisms underlying these enhancements,
+however, remain unclear, largely due to the inherent complexities and
+limitations of powder materials. Here, we fabricate TiO2 homojunction films
+consisting of an oxygen-deficient amorphous layer on top of a highly
+crystalline layer, to simulate the structural/functional configuration of black
+TiO2 nanoparticles. Metallic conduction is achieved at the
+crystalline-amorphous homointerface via electronic interface reconstruction,
+which we show to be the main reason for the superior properties of black TiO2.
+This work not only achieves an unprecedented understanding of black TiO2, but
+also provides a new perspective for investigating carrier generation and
+transport behavior at oxide interfaces, which are of tremendous fundamental and
+technological interest.",1612.01037v1
+2016-12-05,"Phonon scattering limited mobility in the representative cubic perovskite semiconductors SrGeO$_3$, BaSnO$_3$ and SrTiO$_3$","Cubic perovskite oxides are emerging high-mobility transparent conducting
+oxides (TCOs), but Ge-based TCOs had not been known until the discovery of
+metastable cubic SrGeO$_3$. $0.5 \times 0.4 \times 0.2$-mm$^3$ large single
+crystals of the cubic SrGeO$_3$ perovskite were successfully synthesized
+employing the high-pressure flux method. The phonon spectrum is determined from
+the IR optical reflectance and Raman-scattering analysis to evaluate the
+electron transport governed by optical phonon scattering. A calculated
+room-temperature mobility on the order of $3.9 \times 10^2$
+cm$^2$V$^{-1}$s$^{-1}$ is obtained, identifying cubic SrGeO$_3$ as one of the
+most promising TCOs. Employing classical phonon theory and a combined
+experimental-theoretical approach, a comprehensive analysis of the intrinsic
+electron mobility in the cubic perovskite semiconductors SrGeO$_3$, BaSnO$_3$,
+and SrTiO$_3$ is provided based on the magnitude of polarization and
+eigenfrequency of optically active phonons.",1612.01343v2
+2016-12-09,Complex Quasi-Two-Dimensional Crystalline Order Embedded in VO$_2$ and Other Crystals,"Metal oxides such as VO$_2$ undergo structural transitions to low-symmetry
+phases characterized by intricate crystalline order, accompanied by rich
+electronic behavior. We derive a minimal ionic Hamiltonian based on symmetry
+and local energetics which describes structural transitions involving all four
+observed phases, in the correct order. An exact analysis shows that complexity
+results from the symmetry-induced constraints of the parent phase which forces
+ionic displacements to form multiple interpenetrating groups using
+low-dimensional pathways and distant neighbors. Displacements within each group
+exhibit independent, quasi two-dimensional order, which is frustrated and
+fragile. This selective ordering mechanism is not restricted to VO$_2$: it
+applies to other oxides which show similar complex order.",1612.03212v2
+2016-12-12,Modeling the Effect of Blunt Impact on Mitochondrial Dysfunction in Cartilage,"Mounting evidence for the role of oxidative stress in the degeneration of
+articular cartilage after an injurious impact requires our modeling &
+simulation efforts to temporarily shift from just describing the effect of
+mechanical stress and inflammation on osteoarthritis (OA). The hypothesis that
+the injurious impact causes irreversible damage to chondrocyte mitochondria,
+which in turn increase their production of free radicals, affecting their
+energy production and their ability to rebuild the extracellular matrix, has to
+be modeled and the processes quantified in order to further the understanding
+of OA, its causes, and viable treatment options. The current article presents a
+calibrated model that captures the damage oxidative stress incurs on the cell
+viability, ATP production, and cartilage stability in a cartilage explant after
+a drop-tower impact. The model validates the biological hypothesis and will be
+used in further efforts to identify possibilities for treatment and be a part
+of a bigger modeling & simulation framework for the development of OA.",1612.03859v1
+2016-12-13,Electrical Double Layer Properties of Spherical Oxide Nanoparticles,"The accurate characterization of electrical double layer properties of
+nanoparticles is of fundamental importance for optimizing their physicochemical
+properties for specific biotechnological and biomedical applications. In this
+article, we use classical solvation density functional theory and a surface
+complexation model to investigate the effects of pH and nanoparticle size on
+the structural and electrostatic properties of an electrolyte solution
+surrounding a spherical silica oxide nanoparticle. The formulation has been
+particularly useful for identifying dominant interactions governing the ionic
+driving force under a variety of pH levels and nanoparticle sizes. As a result
+of the energetic interplay displayed between electrostatic potential, ion-ion
+correlation and particle crowding effects on the nanoparticle surface
+titration, rich, non-trivial ion density profiles and mean electrostatic
+potential behavior have been found.",1612.03984v1
+2016-12-22,Nonlinear photoluminescence imaging of isotropic and liquid crystalline dispersions of graphene oxide,"We report a visible-range nonlinear photoluminescence (PL) from graphene
+oxide (GO) flakes excited by near-infrared femtosecond laser light. PL
+intensity has nonlinear dependence on the laser power, implying a multiphoton
+excitation process, and also strongly depends on a linear polarization
+orientation of excitation light, being at maximum when it is parallel to
+flakes. We show that PL can be used for a fully three-dimensional label-free
+imaging of isotropic, nematic, and lamellar liquid crystalline dispersions of
+GO flakes in water. This nonlinear PL is of interest for applications in direct
+label-free imaging of composite materials and study of orientational ordering
+in mesomorphic phases formed by these flakes, as well as in biomedical and
+sensing applications utilizing GO.",1612.07444v1
+2017-06-07,Digital modulation of the nickel valence state in a cuprate-nickelate heterostructure,"Layer-by-layer oxide molecular beam epitaxy has been used to synthesize
+cuprate-nickelate multilayer structures of composition
+(La$_2$CuO$_4$)$_m$/LaO/(LaNiO$_3$)$_n$. In a combined experimental and
+theoretical study, we show that these structures allow a clean separation of
+dopant and doped layers. Specifically, the LaO layer separating cuprate and
+nickelate blocks provides an additional charge that, according to density
+functional theory calculations, is predominantly accommodated in the
+interfacial nickelate layers. This is reflected in an elongation of bond
+distances and changes in valence state, as observed by scanning transmission
+electron microscopy and x-ray absorption spectroscopy. Moreover, the predicted
+charge disproportionation in the nickelate interface layers leads to a
+thickness-dependent metal-to-insulator transition for $n=2$, as observed in
+electrical transport measurements. The results exemplify the perspectives of
+charge transfer in metal-oxide multilayers to induce doping without introducing
+chemical and structural disorder.",1706.02173v2
+2017-06-25,"A review on the progress of polymer nanostructures with modulated morphologies and properties, using nonporous AAO templates","Polymers with the same chemical composition can provide different properties
+by reducing the dimension or simply by altering their nanostructure. Recent
+literature works report hundreds of examples of advances methods in the
+fabrication of polymer nanostructures accomplished following different
+approaches, soft lithography, self-assembly routes, template assisted methods,
+etc. Polymer nanostructures with modulated morphologies and properties can be
+easily achieved from anodized aluminum oxide (AAO) templates assisted methods.
+In the last decade, fabrication of polymer nanostructures in the nanocavities
+of AAO has raised a great interest since allows the control and tailoring of
+dimension of a huge number of polymer and polymer-based composites materials.
+The fact that polymer dimension can be adjusted allow the study of
+size-dependency properties. Moreover, modulated polymer nanostructures can be
+designed for specific applications from AAO templates methods. Taking into
+account the last considerations, this review present an overview of recent and
+new insights in the fabrication methods of polymer nanostructures from hard
+porous Anodic Aluminum Oxide (AAO) templates with emphasis on the study of
+polymer structure/property relationship at nanometric scale and stressing the
+potential interest in particular applications.",1706.08069v1
+2017-06-28,Unravelling Single Atom Catalysis: The Surface Science Approach,"Understanding the fundamental mechanisms of single-atom catalysis (SAC) is
+important to design systems with improved performance and stability. This is
+problematic, however, because single-atom active sites are extremely difficult
+to characterize with existing experimental techniques. Over the last 40 years,
+surface science has provided the fundamental insights to understand
+heterogeneous catalysis, but model systems in which metal atoms are stable on
+well-characterized metal-oxide substrates at reaction temperatures are scarce.
+In this perspective, I discuss what is already known about isolated metal atoms
+adsorbed on model metal-oxide surfaces, and how this information can be used to
+understand SAC. A key issue is that, although the highly-idealised model
+systems studied in surface science may not be representative of a real working
+catalyst, they do very much resemble what can be calculated using
+state-of-the-art theoretical modelling. Thus, surface science offers an
+opportunity to rigorously benchmark the theoretical approach to modelling SAC
+in future. Perhaps more excitingly, several groups have developed model systems
+where metal adatoms remain stable at elevated temperatures. To date however,
+there has been no clear demonstration of catalytic activity. The perspective
+closes with a brief discussion of the prospect for STM experiments under
+realistic reaction conditions.",1706.09473v1
+2017-07-11,Hole spin resonance and spin-orbit coupling in a silicon metal-oxide-semiconductor field-effect transistor,"We study hole spin resonance in a p-channel silicon metal-oxide-semiconductor
+field-effect transistor. In the sub-threshold region, the measured source-drain
+current reveals a double dot in the channel. The observed spin resonance
+spectra agree with a model of strongly coupled two-spin states in the presence
+of a spin-orbit-induced anti-crossing. Detailed spectroscopy at the
+anti-crossing shows a suppressed spin resonance signal due to
+spin-orbit-induced quantum state mixing. This suppression is also observed for
+multi-photon spin resonances. Our experimental observations agree with
+theoretical calculations.",1707.03106v1
+2017-07-11,Novel high-pressure calcium carbonates,"Calcium and magnesium carbonates are believed to be the host compounds for
+most of the oxidized carbon in the Earth's mantle. Here, using evolutionary
+crystal structure prediction method USPEX, we systematically explore the
+MgO-CO2 and CaO-CO2 systems at pressures ranging from 0 to 160 GPa to search
+for thermodynamically stable magnesium and calcium carbonates. While MgCO3 is
+the only stable magnesium carbonate, three calcium carbonates are stable under
+pressure: well-known CaCO3, and newly predicted Ca3CO5 and CaC2O5. Ca3CO5
+polymorphs are found to contain isolated orthocarbonate (CO4)4- tetrahedra, and
+are stable at relatively low pressures (>11 GPa), whereas CaC2O5 is stable
+above 33 GPa and its polymorphs feature polymeric motifs made of CO4
+tetrahedra. Detailed analysis of chemical stability of CaCO3, Ca3CO5 and CaC2O5
+in the environment typical of the Earth's lower mantle reveals that none of
+these compounds can exist in the Earth's lower mantle. We conclude that MgCO3
+is the main host of oxidized carbon throughout the lower mantle.",1707.03226v2
+2017-07-18,Insulator to Metal Transition in WO$_3$ Induced by Electrolyte Gating,"Tungsten oxide and its associated bronzes (compounds of tungsten oxide and an
+alkali metal) are well known for their interesting optical and electrical
+characteristics. We have modified the transport properties of thin WO$_3$ films
+by electrolyte gating using both ionic liquids and polymer electrolytes. We are
+able to tune the resistivity of the gated film by more than five orders of
+magnitude, and a clear insulator-to-metal transition is observed. To clarify
+the doping mechanism, we have performed a series of incisive operando
+experiments, ruling out both a purely electronic effect (charge accumulation
+near the interface) and oxygen-related mechanisms. We propose instead that
+hydrogen intercalation is responsible for doping WO$_3$ into a highly
+conductive ground state and provide evidence that it can be described as a
+dense polaronic gas.",1707.05748v1
+2017-07-21,Generation of multiple plasmons in strontium niobates mediated by local field effects,"Recently, an anomalous generation of multiple plasmons with large spectral
+weight transfer in the visible to ultraviolet range (energies below the band
+gap) has been experimentally observed in the insulating-like phase of
+oxygen-rich strontium niobium oxides (SrNbO$_{3+\delta}$). Here, we investigate
+the ground state and dielectric properties of SrNbO$_{3+\delta}$ as a function
+of $\delta$ by means of extensive first principle calculations. We find that in
+the random phase approximation by taking into account the local field effects
+(LFEs), our calculations are able to reproduce both the unconventional multiple
+generations of plasmons and spectral weight transfers, consistent with
+experimental data. Interestingly, these unconventional plasmons can be tuned by
+oxygen stoichiometry as well as microscopic superstructure. This unusual
+predominance of LFEs in this class of materials is ascribed to the strong
+electronic inhomogeneity and high polarizability and paves a new path to induce
+multiple plasmons in the untapped visible to ultraviolet ranges of
+insulating-like oxides.",1707.06738v2
+2017-07-26,Atomistic Mechanisms for the Nucleation of Aluminium Oxide Nanoparticles,"A predictive model for nanoparticle nucleation has not yet been successfully
+achieved. Classical nucleation theory fails because the atomistic nature of the
+seed has to be considered since geometrical structure as well as stoichiometry
+do not always match the bulk values. We present a fully microscopic approach
+based on a first-principle study of aluminium oxide clusters. We have
+calculated stable structures of AlxOy} and their associated thermodynamic
+properties. From these data, the chemical composition of a gas composed of
+aluminium and oxygen atoms can be calculated as a function of temperature,
+pressure, and aluminium to oxygen ratio. We demonstrate the accuracy of this
+approach in reproducing experimental results obtained with time resolved
+spectroscopy of a laser induced plasma from an Al2O3} target. We thus extended
+the calculation to lower temperatures, i.e. longer time scales, to propose a
+scenario of composition gas evolution leading to the first alumina seeds.",1707.08434v1
+2017-07-28,Exciton mass and exciton spectrum in the cuprous oxide,"Excitons with a radius of a few lattice constants can be affected by strong
+central-cell corrections, leading to significant deviations of the optical
+spectrum from the hydrogen-like Rydberg series, and also to an enhancement of
+the exciton mass. We present an approach to this situation based on a lattice
+model that incorporates the effects of a non-parabolic band structure, short
+distance corrections to the Coulomb interaction between electrons and holes,
+spin-orbit and exchange coupling. The lattice model allows for observation of
+the crossover from large radius Wannier to small radius Frenkel excitons
+without invoking a continuum approximation. We apply the lattice model approach
+especially to the yellow exciton series in the cuprous oxide, for which the
+optical spectrum and exciton mass enhancement are obtained through adaptation
+of only a few model parameters to material-specific values. Our results predict
+a strongly anisotropic ortho-exciton mass.",1707.09224v2
+2017-07-29,Extraordinary water adsorption characteristics of graphene oxide,"The laminated structure of graphene oxide (GO) confers unique interactions
+with water molecules which may be utilised in a range of applications that
+require materials with tuneable hygroscopic properties. Precise roles of the
+expandable interlayer spacing and functional groups in GO laminates are not
+fully understood till date. Herein, we report experimental and theoretical
+study on the adsorption and desorption behaviour of water in GO laminates as a
+function of relative pressure. We have observed that GO imparts excellent water
+uptake capacity of up to 0.58 gram of water per gram of GO (g g-1), which is
+much higher than silica gel a conventional desiccant material. More
+interestingly, the adsorption and desorption kinetics of GO is one order of
+magnitude higher than silica gel. The observed extraordinary
+adsorption/desorption rate can be attributed to the high capillary pressure in
+GO laminates as well as micro meter sized tunnel like wrinkles located at the
+surface.",1707.09502v1
+2017-10-03,The efficient photodesorption of nitric oxide (NO) ices A laboratory astrophysics study,"The study and quantification of UV photon-induced desorption of frozen
+molecules furthers our understanding of the chemical evolution of cold
+interstellar regions. Nitric oxide (NO) is an important intermediate species in
+both gas-phase and solid-phase chemical networks. In this work, we present
+quantitative measurements of the photodesorption of a pure NO ice.We used the
+tunable monochromatic synchrotron light of the DESIRS beamline of the SOLEIL
+facility near Paris to irradiate NO ices in the 6 - 13.6 eV range and measured
+desorption by quadrupole mass spectrometry.We find that NO photodesorption is
+very efficient, its yield being around 1e-2 molecule per incident photon for UV
+fields relevant to the diffuse and dense interstellar medium. We discuss the
+extrapolation of our results to an astrophysical context and we compare
+photodesorption of NO to previously studied molecules.",1710.01028v1
+2017-10-09,Asymmetrically Encapsulated vertical ITO/MoS2/Cu2O photodetector with ultra-high sensitivity,"Strong light absorption, coupled with moderate carrier transport properties,
+makes two-dimensional (2-D) layered transition metal dichalcogenide (TMD)
+semiconductors promising candidates for low intensity photodetection
+applications. However, the performance of these devices is severely
+bottlenecked by slow response with persistent photocurrent due to long lived
+charge trapping, and nonreliable characteristics due to undesirable ambience
+and substrate effects. Here we demonstrate ultra-high specific detectivity (D*)
+of 3.2x10^14 Jones and responsivity (R) of 5.77x10^4 AW-1 at an optical power
+density (P_op) of 0.26 Wm-2 and external bias (V_ext) of -0.5 V in an indium
+tin oxide (ITO)/MoS2/copper oxide (Cu2O)/Au vertical multi-heterojunction
+photodetector exhibiting small carrier transit time. The active MoS2 layer
+being encapsulated by carrier collection layers allows us to achieve negligible
+trap assisted persistent photocurrent and repeatable characteristics over large
+number of cycles. We also achieved a large D*>10^14 Jones at zero external bias
+due to the built-in field of the asymmetric photodetector. Benchmarking the
+performance against existing reports in literature shows a pathway for
+achieving reliable and highly sensitive photodetectors for ultra-low intensity
+photodetection applications.",1710.02967v1
+2017-10-10,Room Temperature deposition of ZnO and Al:ZnO ultrathin films on glass and PET substrates by DC sputtering Technique,"In the present work, ultrathin films of Zinc oxide (ZnO) and Aluminum doped
+zinc oxide (AZO) with 20 nm thick were fabricated at 300 K on glass and
+Polyethylene terephthalate (PET) substrates by means of directcurrent
+sputtering method. The structural morphology of the films were analyzed by
+(XRD) diffractometry. The average transmittance of films deposited on different
+substrates showed high transparency (over 80%) in the visible spectrum. The
+objective of the present work is to investigate the thicknesses and optical
+constants of ZnO and AZO ultrathin films prepared by DC sputtering onto (glass
+and PET) substrates using two methods (UV-vis-NIR spectrophotometer and
+ellipsometer (SE) by new amorphous dispersion formula) with comparison to check
+and confirm the results that obtained from UV with those obtained from SE
+measurements. The optical constants of films were extracted and compared using
+UV and SE techniques in the range of (200- 2200 nm) with increment of 1 nm in
+order to confirm the accuracy of the UV and shown an excellent agreement.",1710.03493v1
+2017-10-22,Electronic Stopping of Slow Protons in Oxides: Scaling Properties,"Electronic stopping of slow protons in ZnO, VO2 (metal and semiconductor
+phases), HfO2, and Ta2O5 was investigated experimentally. As a comparison of
+the resulting stopping cross sections (SCS) to data for Al2O3 and SiO2 reveals,
+electronic stopping of slow protons does not correlate with electronic
+properties of the specific material such as band gap energies. Instead, the
+oxygen 2p states are decisive, as corroborated by density functional theory
+calculations of the electronic densities of states. Hence, at low ion
+velocities the SCS of an oxide primarily scales with its oxygen density.",1710.07994v1
+2017-10-24,Atomic layer control of metal-insulator behavior in oxide quantum wells integrated directly on silicon,"We present electrical and structural characterization of epitaxial
+LaTiO3/SrTiO3 quantum wells integrated directly on Si(100). The quantum wells
+exhibit metallic transport described by Fermi-liquid behavior. Carriers arise
+from both charge transfer from the LaTiO3 to SrTiO3 and oxygen vacancies in the
+latter. By reducing the thickness of the quantum wells, an enhancement in
+carrier-carrier scattering is observed, and insulating transport emerges.
+Consistent with a Mott-driven transition in bulk rare-earth titanates, the
+insulating behavior is described by activated transport, and the onset of
+insulating transport occurs near 1 electron per Ti occupation within the SrTiO3
+well. We also discuss the role that structure and gradients in strain may play
+in enhancing the carrier density. The manipulation of metal-insulator behavior
+in oxides grown directly on Si opens the pathway to harnessing strongly
+correlated phenomena in device technologies.",1710.08597v1
+2017-10-26,First-principles theory of doping in layered oxide electrode materials,"Doping lithium-ion battery electrode materials LiMO$_2$ (M = Co, Ni, Mn) with
+impurities has been shown to be an effective way to optimize their
+electrochemical properties. Here, we report a detailed first-principles study
+of layered oxides LiCoO$_2$, LiNiO$_2$, and LiMnO$_2$ lightly doped with
+transition-metal (Fe, Co, Ni, Mn) and non-transition-metal (Mg, Al) impurities
+using hybrid-density-functional defect calculations. We find that the lattice
+site preference is dependent on both the dopant's charge and spin states, which
+are coupled strongly to the local lattice environment and can be affected by
+the presence of co-dopant(s), and the relative abundance of the host compound's
+constituting elements in the synthesis environment. On the basis of the
+structure and energetics of the impurities and their complexes with intrinsic
+point defects, we determine all possible low-energy impurity-related defect
+complexes, thus providing defect models for further analyses of the materials.
+From a materials modeling perspective, these lightly doped compounds also serve
+as model systems for understanding the more complex, mixed-metal,
+LiMO$_2$-based battery cathode materials.",1710.09895v1
+2017-12-01,Titanium Contacts to Graphene: Process-Induced Variability in Electronic and Thermal Transport,"Contact Resistance (RC) is a major limiting factor in the performance of
+graphene devices. RC is sensitive to the quality of the interface and the
+composition of the contact, which are affected by the graphene transfer process
+and contact deposition conditions. In this work, a linear correlation is
+observed between the composition of Ti contacts, characterized by X-ray
+photoelectron spectroscopy, and the Ti/graphene (Gr) contact resistance
+measured by the transfer length method. We find that contact composition is
+tunable via deposition rate and base pressure. Reactor base pressure is found
+to effect the resultant contact resistance. The effect of contact deposition
+conditions on thermal transport measured by time-domain thermoreflectance is
+also reported and interfaces with higher oxide composition appear to result in
+a lower thermal boundary conductance. Possible origins of this thermal boundary
+conductance change with oxide composition are discussed.",1712.00331v1
+2017-12-04,Characterizations of the Nonlinear Optical Properties for (010) and (-201) Beta-phase Gallium Oxide,"We report, for the first time, the characterizations on optical
+nonlinearities of beta-phase gallium oxide (\b{eta}-Ga2O3), where both (010)
+\b{eta}-Ga2O3 and (-201) \b{eta}-Ga2O3 were examined for two-photon absorption
+(TPA) coefficient, Kerr refractive index, and their polarization dependence.
+The wavelength dependence of the TPA coefficient and Kerr refractive index was
+estimated using a widely used analytical model. \b{eta}-Ga2O3 exhibits a TPA
+coefficient of 1.2 cm/GW for (010) \b{eta}-Ga2O3 and 0.58 cm/GW for (-201)
+\b{eta}-Ga2O3. The Kerr refractive index is -2.14*10^(15) cm2/W for (010)
+\b{eta}-Ga2O3 and -2.89*10^(15) cm2/W for (-201) \b{eta}-Ga2O3. In addition,
+\b{eta}-Ga2O3 shows stronger nonlinear optical anisotropy on the (-201) plane
+than on the (010) plane, possibly due to highly asymmetric crystal structure.
+Compared with that of gallium nitride (GaN), the TPA coefficient of
+\b{eta}-Ga2O3 is 20 times smaller, and the Kerr refractive index of
+\b{eta}-Ga2O3 is also found to be 4 to 5 times smaller. These results indicate
+that \b{eta}-Ga2O3 has the potential for use in ultra-low loss waveguides and
+ultra-stable resonators and integrated photonics, especially in the UV and
+visible wavelength spectral range.",1712.01390v1
+2017-12-07,Nature of the growth of plasma electrolyte oxidation coating on Aluminum,"The localized dielectric breakdown had been considered as the driving force
+for growth of plasma electrolytic oxide (PEO) coatings for several decades.
+However, the TEM study here reveals the dielectric breakdown behavior has
+little contribution for coating thickening. The presented evidences show the
+nature of PEO coating growth in all three consecutive stages I-III is ionic
+migration behavior inside the amorphous alumina layer (AAL) at the
+coating/matrix interface. The evolution of morphological characterizations in
+the PEO process is attributed to the interfacial reactions of AAL/alkaline
+(stage I), AAL/discharge-on-surface (stage II) and AAL/discharge-in-pore (stage
+III).",1712.02459v1
+2017-12-12,Metal - TiO2 contacts: An electrical characterization study,"The electrical properties of thin TiO2 films have recently been extensively
+exploited towards enabling a variety for metal-oxide electron devices:
+unipolar/bipolar semiconductor devices and/or memristors. In such efforts,
+investigations on the role of TiO2 as active material have been the main focus,
+however, electrode materials are equally important. In this work, we address
+this need by presenting a systematic quantitative electrical characterisation
+study on the interface characteristics of Metal-TiO2-Metal structures. Our
+study employs typical contact materials that are used both as top and bottom
+electrodes in a Metal-TiO2-Metal setting. This allows investigating the effect
+of Metal-TiO2 contacts as well as holistically studying an electrode's
+influence to the opposite interface, referred to as top/bottom electrodes
+coupling. Our methodology comprises the recording of current-voltage (I-V)
+characteristics from a variety of solid-state prototypes in the temperature
+range of 300-350 K and by analysing them through appropriate modelling. Clear
+field and temperature dependent signature plots were also obtained towards
+shinning more light on the role of each material as top/bottom electrodes in
+Metal-TiO2-Metal structures. Our results provide a useful database for
+selecting appropriate electrode materials in Metal-TiO2 devices, offering new
+insights in metal-oxide electronics applications.",1712.04218v1
+2017-12-21,Excitation of epsilon-near-zero resonance in ultra-thin indium tin oxide shell embedded nanostructured optical fiber,"We report a novel optical waveguide design of a hollow step index fiber
+modified with a thin layer of indium tin oxide (ITO). We show an excitation of
+highly confined waveguide mode in the proposed fiber near the wavelength where
+permittivity of ITO approaches zero. Due to the high field confinement within
+thin ITO shell inside the fiber, the epsilon-near-zero (ENZ) mode can be
+characterized by a peak in modal loss of the hybrid waveguide. Our results show
+that such in-fiber excitation of ENZ mode is due to the coupling of the guided
+core mode to the thin-film ENZ mode. We also show that the phase matching
+wavelength, where the coupling takes place, varies depending on the refractive
+index of the constituents inside the central bore of the fiber. These ENZ
+nanostructured optical fibers have many potential applications, for example, in
+ENZ nonlinear and magneto-optics, as in-fiber wavelength-dependent filters, and
+as subwavelength fluid channel for optical and bio-photonic sensing.",1712.08202v1
+2018-01-04,Reconstruction-Stabilized Epitaxy of LaCoO3/SrTiO3(111) Heterostructures by Pulsed Laser Deposition,"Unlike widely explored complex oxide heterostructures grown along [001], the
+study of [111]-oriented heterointerfaces are very limited thus far. One of the
+main challenges is to overcome the polar discontinuity that hinders the epitaxy
+of atomically sharp interfaces. Here, by taking the LaCoO3/SrTiO3(111) as a
+prototype, we show that the reconstruction, which effectively compensates the
+surface polarity, can stabilize the epitaxy of the heterostructure with polar
+discontinuity. Reconstructed substrate surface is prepared, while the growth is
+controlled to form reconstruction on the film surface. To suppress the chemical
+diffusion across the interface, the growth is interrupted between each unit
+cell layer to allow the lattice relaxation at a lowered temperature. In this
+way, high quality two-dimensional growth is realized and the heterointerfaces
+exhibit sharpness at the atomic scale. Our work provides a path to precisely
+control the growth of complex oxide heterostructures along polar orientations
+that exhibit emergent quantum phenomena.",1801.01287v1
+2018-01-15,Weighting graphene with QCM to monitor interfacial mass changes,"In this Letter, using quartz crystal microbalance (QCM), we experimentally
+determined the mass density of graphene grown by chemical vapor deposition
+method. We developed a transfer printing technique to integrate large area
+single-layer graphene on QCM. By monitoring the resonant frequency of an
+oscillating quartz crystal loaded with graphene, we were able to measure the
+mass density of graphene as ~118 ng/cm2, which is significantly larger than the
+ideal graphene (~76 ng/cm2) mainly due to the presence of wrinkles and
+organic/inorganic residues on graphene sheets. High sensitivity of quartz
+crystal resonator allowed us to determine the number of graphene layers in
+samples. (The technique is very sensitive and able to determine the number of
+graphene layers in a particular sample.) Besides, we extended our technique to
+probe interfacial mass variation during adsorption of biomolecules on graphene
+surface, and plasma-assisted oxidation of graphene. (Besides, we extended our
+technique to probe interfacial mass variation during adsorption of biomolecules
+on graphene surface, and plasma-assisted oxidation of graphene.)",1801.04755v1
+2018-09-01,When supporting electrolyte matters - tuning capacitive response of graphene oxide via electrochemical reduction in alkali and alkaline earth metal chlorides,"The ability to tune charge storage properties of graphene oxide (GO) is of
+utmost importance for energy conversion applications. Here we show that
+electrochemical reduction of GO is highly sensitive to the cations present in
+the solution. GO is reduced at lower potential in alkali metal chloride
+solutions than in alkaline earth metal chlorides. During the reduction,
+capacitance of GO increases from 10 to 70 times. Maximum capacitances of
+reduced GO are between 65 and 130 F g-1, depending on the electrolyte and the
+presence of conductive additive. We propose that different interactions of
+cations with oxygen functional groups of GO during the reduction are
+responsible for the observed effect.",1809.00265v1
+2018-09-05,A combined approach of Lattice Boltzmann Method and Maxwell-Stefan equation for modeling multi-component diffusion in solid oxide fuel cell,"Lattice Boltzmann models provide better understanding with mesoscopic
+eyesight on multi-component diffusion than macroscopic models. Based on the
+kinetic theory and starting from the He-Luo model, the state-of-the-art
+multi-component diffusion Lattice Boltzmann models have defects of the
+compressible error and the limitations for velocity and viscosity settings in
+lattice units. With these respects, a new Lattice Boltzmann model is presented
+based on the advection-diffusion equation and is coupled with the
+Maxwell-Stefan equation by relaxation time. Without introducing the pressure
+term into the advection-diffusion equation, the model avoids the compressible
+error. Furthermore, the velocities for components are calculated in the
+Maxwell-Stefan equation and not contained in the equilibrium distribution
+function, the limitations of the velocity and viscosity settings in lattice
+units for under-relaxation iterations are reduced. Then a simulation for
+H2-H2O-Ar ternary mass transport in the porous anode of the solid oxide fuel
+cell is employed to validate the accuracy of the Lattice Boltzmann model. The
+concentration overpotentials are calculated accordingly and compared to several
+published continuum-scale and Lattice Boltzmann computations, among them, our
+model offers a better consistency with the experimental measurments.",1809.01600v1
+2018-09-07,"Space-filling, multi-fractal, localized thermal spikes in silicon, germanium and zinc oxide","The mechanism responsible for the emission of clusters from heavy ion
+irradiated solids is proposed to be thermal spikes. Collision cascade-based
+theories describe atomic sputtering but cannot explain the consistently
+observed experimental evidence for significant cluster emission. Statistical
+thermodynamic arguments for thermal spikes are employed here for qualitative
+and quantitative estimation of the thermal spike-induced cluster emission from
+silicon, germanium and zinc oxide. The evolving cascades and spikes in
+elemental and molecular semiconducting solids are shown to have fractal
+characteristics. Power law potential is used to calculate the fractal
+dimension.The fractal dimension is shown to be dependent upon the exponent of
+the power law interatomic potential. Each irradiating ion has the probability
+of initiating a space-filling, multi-fractal thermal spike that may sublime a
+localized region near the surface by emitting clusters in relative ratios that
+depend upon the energies of formation of respective surface vacancies.",1809.02447v1
+2018-09-20,"Synthesis, structural and photo physical properties of perovskite oxide (KNbO3)1-X+(La2NiMnO6)X for photovoltaic application","Solid solutions of perovskite oxides (KNbO3)1-x+(La2NiMnO6)x (x=0, 0.1, 0.2
+and 0.3) with a variation of band gap (1.33-3.6 eV) have been introduced as a
+promising photovoltaic absorber. The structural characterization of the
+prepared samples was carried out using X-ray diffraction (followed by Rietveld
+refinement) and Raman experiment. As the doping percentage of the monoclinic
+La2NiMnO6 in the solid-solution increases, the crystal structure of host KNbO3
+becomes more symmetric from orthorhombic to cubic. A large reduction in the
+particle size has also been observed in the solid solutions in comparison to
+the pure KNbO3. The band gap (~ 1.33 eV) of the synthesized solid solution
+x=0.1 is found to be very close to the Shockley-Queisser band gap value of 1.34
+eV, which suggests the promising photovoltaic possibility in this material.
+Photoluminescence (PL) emission spectra reveal a strong PL quenching in the
+solid-solutions in comparison to the KNbO3. The overall structural and optical
+studies suggest the promising photovoltaic possibility in KNbO3/ La2NiMnO6
+solid solution.",1809.07569v1
+2018-09-25,Normal-state properties of the antiperovskite oxide Sr$_{3-x}$SnO revealed by $^{119}$Sn-NMR,"We have performed $^{119}$Sn-NMR measurements on the antiperovskite oxide
+superconductor Sr$_{3-x}$SnO to investigate how its normal state changes with
+the Sr deficiency. A two-peak structure was observed in the NMR spectra of all
+the measured samples. This suggests that the phase separation tends to occur
+between the nearly stoichiometric and heavily Sr-deficient Sr$_{3-x}$SnO
+phases. The measurement of the nuclear spin-lattice relaxation rate $1/T_1$
+indicates that the Sr-deficient phase shows a conventional metallic behavior
+due to the heavy hole doping. In contrast, the nearly stoichiometric phase
+exhibits unusual temperature dependence of $1/T_1$, attributable to the
+presence of a Dirac-electron band.",1809.09275v1
+2018-09-27,p-GaAs nanowire MESFETs with near-thermal limit gating,"Difficulties in obtaining high-performance p-type transistors and gate
+insulator charge-trapping effects present two major challenges for III-V
+complementary metal-oxide semiconductor (CMOS) electronics. We report a p-GaAs
+nanowire metal-semiconductor field-effect transistor (MESFET) that eliminates
+the need for a gate insulator by exploiting the Schottky barrier at the
+metal-GaAs interface. Our device beats the best-performing p-GaSb nanowire
+metal-oxide-semiconductor field effect transistor (MOSFET), giving a typical
+sub-threshold swing of 62 mV/dec, within 4% of the thermal limit, on-off ratio
+$\sim 10^{5}$, on-resistance ~700 k$\Omega$, contact resistance ~30 k$\Omega$,
+peak transconductance 1.2 $\mu$S/$\mu$m and high-fidelity ac operation at
+frequencies up to 10 kHz. The device consists of a GaAs nanowire with an
+undoped core and heavily Be-doped shell. We carefully etch back the nanowire at
+the gate locations to obtain Schottky-barrier insulated gates whilst leaving
+the doped shell intact at the contacts to obtain low contact resistance. Our
+device opens a path to all-GaAs nanowire MESFET complementary circuits with
+simplified fabrication and improved performance.",1809.10479v1
+2018-10-05,A Corkscrew Model for Highly Coupled Anisotropic Compliance in Ruddlesden-Popper Oxides with Frozen Octahedral Rotations,"A ""corkscrew"" mechanism, that couples changes in the in-plane rotation angle
+to strains along the layering axis, has been proposed previously to explain
+increased compliance in certain Ruddlesden-Popper phases that facilitates
+uniaxial negative thermal expansion over a wide temperature range. Following
+the procedure developed to study many simple, auxetic geometries, in the
+present study we derive the elastic compliances predicted by this corkscrew
+mechanism assuming that the four shortest metal-anion bonds remain stiff and
+changes in bond angle are modelled by a harmonic angle potential. We
+subsequently analyse the limitations of this model and show that it may be
+extended to An+1BnO3n+1 Ruddlesden-Popper oxide phases of general layer
+thickness n.",1810.02697v1
+2018-10-10,Capturing the oxidation of silicon carbide in rocky exoplanetary interiors,"Theoretical models predict the condensation of silicon carbide around host
+stars with C/O ratios higher than 0.65 (cf. C/O$_{\mathrm{Sun}}$ = 0.54), in
+addition to its observations in meteorites, interstellar medium and
+protoplanetary disks. Consequently, the interiors of rocky exoplanets born from
+carbon-enriched refractory material are often assumed to contain large amounts
+of silicon carbide. Here we aim to investigate the stability of silicon carbide
+in the interior of carbon-enriched rocky exoplanets and to derive the reaction
+leading to its transformation. We performed a high-pressure high-temperature
+experiment to investigate the reaction between a silicon carbide layer and a
+layer representative of the bulk composition of a carbon-enriched rocky
+exoplanet. We report the reaction leading to oxidation of silicon carbide
+producing quartz, graphite, and molten iron silicide. Combined with previous
+studies, we show that in order to stabilize silicon carbide, carbon saturation
+is not sufficient, and a complete reduction of Fe$^{2+}$ to Fe$^{0}$ in a
+planetary mantle is required, suggesting that future spectroscopic detection of
+Fe$^{2+}$ or Fe$^{3+}$ on the surface of rocky exoplanets would imply the
+absence of silicon carbide in their interiors.",1810.04544v1
+2018-10-11,Are Small Polarons Always Detrimental to Transparent Conducting Oxides ?,"Transparent conducting oxides (TCOs) are essential to many technologies
+including solar cells and transparent electronics. The search for high
+performance n- or p-type TCOs has mainly focused on materials offering
+transport through band carriers instead of small polarons. In this work, we
+break this paradigm and demonstrate using well-known physical models that, in
+certain circumstances, TCOs exhibiting transport by small polarons offer a
+better combination of transparency and conductivity than materials conducting
+through band transport. We link this surprising finding to the fundamentally
+different physics of optical absorption for band and polaronic carriers. Our
+work rationalizes the good performances of recently emerging small-polaronic
+Cr-based p-type TCOs such as Sr-doped LaCrO$_3$ and outlines design principles
+for the development of high-performance TCOs based on transport by small
+polarons. This opens new avenues for the discovery of high-performance TCOs
+especially p-type.",1810.04919v1
+2018-10-12,Superconductivity From Confinement of Singlets in Metal Oxides,"The Yang-Mills description of phonons and the consequent structure of
+electron liquids in strongly anharmonic crystals such as metal oxides is shown
+to yield an attractive electron-phonon interaction, and thus an instability
+towards the formation of bound states, which can condense to form a
+superconductor. This mechanism differs significantly from the pairing mechanism
+of conventional superconductivity: the ground state from which
+superconductivity emerges is a many-body state of paired electrons and holes
+which is not amenable to a quasiparticle description, and whose properties are
+similar to those seen in the Cuprate high temperature superconductors.
+Confinement arises because the electron liquid structure acts as a source for
+Yang-Mills bosons, and not the traditional longitudinal density waves of BCS
+pairing.",1810.05339v2
+2018-10-10,400%/W second harmonic conversion efficiency in $\mathrm{14 μ m}$-diameter gallium phosphide-on-oxide resonators,"Second harmonic conversion from 1550~nm to 775~nm with an efficiency of 400%
+W$^{-1}$ is demonstrated in a gallium phosphide (GaP) on oxide integrated
+photonic platform. The platform consists of doubly-resonant, phase-matched ring
+resonators with quality factors $Q \sim 10^4$, low mode volumes $V \sim 30
+(\lambda/n)^3$, and high nonlinear mode overlaps. Measurements and simulations
+indicate that conversion efficiencies can be increased by a factor of 20 by
+improving the waveguide-cavity coupling to achieve critical coupling in current
+devices.",1810.06393v1
+2018-10-18,Two-dimensional hybrid composites of SnS2 with graphene and graphene oxide for improving sodium storage: A first-principles study,"Among the recent achievements of sodium-ion battery (SIB) electrode
+materials, hybridization of two-dimentional (2D) materials is one of the most
+interesting appointments. In this work, we propose to use the 2D hybrid
+composites of SnS2 with graphene or graphene oxide (GO) layers as SIB anode,
+based on the first-principles calculations of their atomic structures, sodium
+intercalation energetics and electronic properties. The calculations reveal
+that graphene or GO film can effectively support not only the stable formation
+of hetero-interface with the SnS2 layer but also the easy intercalation of
+sodium atom with low migration energy and acceptable low volume change. The
+electronic charge density differences and the local density of state indicate
+that the electrons are transferred from the graphene or GO layer to the SnS2
+layer, facilitating the formation of hetero-interface and improving the
+electronic conductance of the semiconducting SnS2 layer. These 2D hybrid
+composites of SnS2/G or GO are concluded to be more promising candidates for
+SIB anodes compared with the individual monolayers.",1810.07864v1
+2018-10-24,Charge transfer tuning in TiO2 hybrid nanostructures with acceptor-acceptor systems,"An interesting interplay between two different modifiers and the surface of
+titanium dioxide leads to a significant change in photoelectrochemical
+properties of the designed hybrid materials. The semiconductor is
+photosensitized by one of the counterparts and exhibits the
+photoelectrochemical photocurrent switching effect thanks to interactions with
+graphene oxide - the second modifier mediates charge transfer processes in the
+system, allowing us to design the materials response at the molecular level.
+Based on the selection of molecular counterpart we may affect the behaviour of
+hybrids upon light irradiation in a different manner, which may be useful for
+the applications in photovoltaics, optoelectronics and photocatalysis. Here we
+focus particularly on the nanocomposites made of titanium dioxide with graphene
+oxide combined with either 2,3,5,6-tetrachlorobenzoquinone or
+2,3-dichloro-5,6-dihydroxybenzoquinone - for these two materials we observed a
+major change in the charge transfer processes occurring in the system.",1810.10522v1
+2018-10-25,Raman Spectroscopy of Diesel and Gasoline Engine-Out Soot Using Different Laser Power,"We studied engine-out soot samples collected from a heavy-duty
+direct-injection diesel engine and a port-fuel injection gasoline
+spark-ignition engine. The two types of soot samples were characterized using
+Raman spectroscopy with different laser power. A Matlab program using
+least-square-method with trust-region-reflective algorithm was developed for
+curve fitting. We used a DOE (design of experiments) method to avoid local
+convergence. This method was used for two-band fitting and three-band fitting.
+The fitting results were used to determine the intensity ratio of D and G Raman
+bands. We find that high laser power may cause oxidation of soot samples, which
+gives higher D/G intensity ratio. Diesel soot has consistently higher
+amorphous/graphitic carbon ratio and thus higher oxidation reactivity, in
+comparison to gasoline soot, which is revealed by the higher D/G intensity
+ratio in Raman spectra measured under the same laser power.",1810.10701v1
+2018-10-26,Lone-pair effect on carrier capture in Cu$_2$ZnSnS$_4$ solar cells,"The performance of kesterite thin-film solar cells is limited by a low
+open-circuit voltage due to defect-mediated electron-hole recombination. We
+calculate the non-radiative carrier-capture cross sections and
+Shockley-Read-Hall recombination coefficients of deep-level point defects in
+Cu$_2$ZnSnS$_4$ (CZTS) from first-principles. While the oxidation state of Sn
+is +4 in stoichiometric CZTS, inert lone pair (5$s^2$) formation lowers the
+oxidation state to +2. The stability of the lone pair suppresses the ionization
+of certain point defects, inducing charge transition levels deep in the band
+gap. We find large lattice distortions associated with the lone-pair defect
+centers due to the difference in ionic radii between Sn(II) and Sn(IV). The
+combination of a deep trap level and large lattice distortion facilitates
+efficient non-radiative carrier capture, with capture cross-sections exceeding
+$10^{-12}$ cm$^2$. The results highlight a connection between redox active
+cations and `killer' defect centres that form giant carrier traps. This lone
+pair effect will be relevant to other emerging photovoltaic materials
+containing n$s^2$ cations.",1810.11259v1
+2018-10-30,Direct coupling of first-principles calculations with replica exchange Monte Carlo sampling of ion disorder in solids,"We demonstrate the feasibility of performing sufficient configurational
+sampling of disordered oxides directly from first principles without resorting
+to the use of fitted models such as cluster expansion. This is achieved by
+harnessing the power of modern-day cluster supercomputers using the replica
+exchange Monte Carlo method coupled directly with structural relaxation and
+energy calculation performed by density functional codes. The idea is applied
+successfully to the calculation of the temperature-dependence of the degree of
+inversion in the cation sublattice of MgAl$_2$O$_4$ spinel oxide. The
+possibility of bypassing fitting models will lead to investigation of
+disordered systems where cluster expansion is known to perform badly: for
+example, systems with large lattice deformation due to defects, or systems
+where long-range interactions dominate such as electrochemical interfaces.",1810.12517v1
+2018-10-30,Substrate induced proximity effect in superconducting niobium nanofilms,"Structural and superconducting properties of high quality Niobium nanofilms
+with different thicknesses are investigated on silicon oxide and sapphire
+substrates. The role played by the different substrates and the superconducting
+properties of the Nb films are discussed based on the defectivity of the films
+and on the presence of an interfacial oxide layer between the Nb film and the
+substrate. The X-ray absorption spectroscopy is employed to uncover the
+structure of the interfacial layer. We show that this interfacial layer leads
+to a strong proximity effect, specially in films deposited on a SiO$_2$
+substrate, altering the superconducting properties of the Nb films. Our results
+establish that the critical temperature is determined by an interplay between
+quantum-size effects, due to the reduction of the Nb film thicknesses, and
+proximity effects.",1810.12643v1
+2019-06-06,Odd-Parity Superconductivity Driven by Octahedra Rotations in Iridium Oxides,"Iridium oxides have provided a playground to study novel phases originating
+from spin-orbit coupling and electron-electron interactions. Among them, the
+d-wave singlet superconductor was proposed for electron-doped Sr$_2$IrO$_4$,
+containing two Ir atoms in a unit cell due to the staggered rotation of oxygen
+octahedra about the c-axis. It was also noted that such oxygen octahedra
+rotation affects electronic transports. Here we study the role of octahedra
+tilting away from the c-axis, in determining superconducting pairing symmetry.
+We show that the octahedra tilting changes the large Fermi surface to a Dirac
+point, which strongly suppresses the conventional d-wave pairing. Furthermore,
+it also promotes effective spin-triplet interactions in the strong Hubbard
+interaction limit, leading to a transition from the even-parity to odd-parity
+superconducting phase. Thus, tuning octahedra distortions can be used as a tool
+to engineer a spin triplet superconductor in strongly correlated systems with
+strong spin-orbit coupling.",1906.02749v1
+2019-06-07,Self-limiting growth of two-dimensional palladium between graphene oxide layers,"The ability of different materials to display self-limiting growth has
+recently attracted enormous attention due to the importance of nanoscale
+materials in applications for catalysis, energy conversion, (opto)electronics,
+etc. Here, we show that electrochemical deposition of palladium (Pd) between
+graphene oxide (GO) sheets result in a self-limiting growth of 5 nm thin Pd
+nanosheets. The self-limiting growth is found to be a consequence of strong
+interaction of Pd with the confining GO sheets which results in bulk growth of
+Pd being energetically unfavourable for larger thicknesses. Furthermore, we
+have successfully carried out liquid exfoliation of the resulting Pd-GO
+laminates to isolate Pd nanosheets and demonstrated their high efficiency in
+continuous flow catalysis and electrocatalysis.",1906.03047v1
+2019-06-03,"The Ratio Law of the Structure Evolution and Stability for Ti$_n$O$_m$ ($n=3$-$18$, $m=1$-$2n$) Clusters","Most theoretical investigations about titanium oxide clusters focus on
+(TiO$_2$)$_n$. However, many Ti$_n$O$_m$ clusters with $m\neq 2n$ are produced
+experimentally. In this work, first-principles calculations are performed to
+probe the evolution of Ti$_n$O$_m$ clusters. Our investigations show that for
+$n=3$-$11$, there exist one relatively stable specie; while for $n=12$-$18$,
+there are two relatively stable species: Ti-rich and O-rich species. HOMO-LOMO
+calculations show that the gap can be tuned by changing the size and
+configurations of Ti$_n$O$_m$ clusters. Our investigation provides insights
+into the evolution of cluster-to-bulk process in titanium oxide.",1906.05354v1
+2019-06-24,Combination of informational storage and logical processing based on an all-oxide asymmetric multiferroic tunnel junction,"Multiferroic tunnel junctions (MFTJs) have already been proved to be
+promising candidates for application in spintronics devices. The coupling
+between tunnel magnetoresistance (TMR) and tunnel electroresistance (TER) in
+MFTJs can provide four distinct resistive states in a single memory cell. Here
+we show that in an all-oxide asymmetric MFTJ of La0.7Sr0.3MnO3 /PbZr0.2Ti0.8O3
+/La0.7Te0.3MnO3 (LSMO/PZT/LTMO) with p-type and n-type electrodes, the
+intrinsic rectification is observed and can be modified by the ferroelectric
+polarization of PZT. Owing to the combined TMR, TER and diode effects, two
+different groups of four resistive states under opposite reading biases are
+performed. With two parallel asymmetric junctions and the appropriate series
+resistance, the coexistence of logic units and quaternary memory cells can be
+realized in the same array devices. The asymmetric MFTJ structure enables more
+possibilities for designing next generation of multi-states memory and logical
+devices with higher storage density, lower energy consumption and significantly
+increased integration level.",1906.09993v1
+2019-06-19,Origin of current-controlled negative differential resistance modes and the emergence of composite characteristics with high complexity,"Current-controlled negative differential resistance has significant potential
+as a fundamental building block in brain-inspired neuromorphic computing.
+However, achieving desired negative differential resistance characteristics,
+which is crucial for practical implementation, remains challenging due to
+little consensus on the underlying mechanism and unclear design criteria. Here,
+we report a material-independent model of current-controlled negative
+differential resistance to explain a broad range of characteristics, including
+the origin of the discontinuous snap-back response observed in many transition
+metal oxides. This is achieved by explicitly accounting for a non-uniform
+current distribution in the oxide film and its impact on the effective circuit
+of the device, rather than a material-specific phase transition. The
+predictions of the model are then compared with experimental observations to
+show that the continuous S-type and discontinuous snap-back characteristics
+serve as fundamental building blocks for composite behaviour with higher
+complexity. Finally, we demonstrate the potential of our approach for
+predicting and engineering unconventional compound behaviour with novel
+functionality for emerging electronic and neuromorphic computing applications.",1907.02651v1
+2019-07-08,Role of Toll-Like Receptors in the interplay between pathogen and damage associated molecular patterns,"Various theoretical studies have been carried out to infer relevant
+protein-protein interactions among pathogens and their hosts. Such studies are
+generally based on preferential attachment of bacteria / virus to their human
+receptor homologs. We have analyzed 17 pathogenic species mainly belonging to
+bacterial and viral pathogenic classes, with the aim to identify the
+interacting human proteins which are targeted by both bacteria and virus
+specifically. Our study reveals that the TLRs play a crucial role between the
+pathogen-associated molecular patterns (PAMPs) and the damage associated
+molecular patterns (DAMPS). PAMPs include bacterial lipopolysaccharides (LPs),
+endotoxins, bacterial flagellin, lipoteichoic acid, peptidoglycan in bacterial
+organisms and nucleic acid variants associated with viral organisms, whereas
+DAMPs are associated with host biomolecules that perpetuate non-infectious
+inflammatory responses. We found out the presence of SOD1 and SOD2 (superoxide
+dismutase) is crucial, as it acts as an anti-oxidant and helps in eliminating
+oxidative stress by preventing damage from reactive oxygen species. Hence, such
+strategies can be used as new therapies for anti-inflammatory diseases with
+significant clinical outcomes.",1907.03512v1
+2019-06-25,Work function tuning of graphene oxide by using cesium applied to low work function tethers,"Low Work Function Tethers (LWT) is long conductors with a segment coated with
+a material that has loosely-bounded electrons. Unlike a standard bare tether
+equipped with an active electron emitter, LWTs close the electrical circuit
+(cathodic contact) with the ambient plasma in a passive manner thanks to the
+thermionic and photoelectric effects. This work presents experimental results
+on a novel procedure for manufacturing LWT samples. Conductive substrates
+(aluminum and copper) have been coated with graphene oxide doped with Cesium by
+using a scalable, simple and cost-effective coating method with an airbrush.
+Both GO and Cs-doped GO (GO/Cs) samples were characterized utilizing X-ray
+spectroscopy, field emission scanning electron microscopy, four-point probe,
+and ultraviolet photoelectron spectroscopy (UPS). They showed that GO sheets
+were successfully doped with Cs atoms, which do not agglomerate on the graphene
+sheets and do not form particles. The UPS results indicated that by doping GO
+sheets with Cs, the work function of GO decreases from 4.6 eV to 3.09 eV, thus
+increasing the applicability of GO as an electron emitter material.",1907.03656v1
+2019-07-15,Effects of Electron-Beam Irradiation on Graphene Oxide,"Graphene oxide (GO) is a nanofilm composed of graphene with various oxygen
+functional groups attached. GO is of interest due to its unique
+mechanical-enhancement properties, its tunable electronic properties, and its
+potential use in the wide-scale production of graphene. Scanning electron
+microscopes (SEMs) are frequently used to characterize and study GO films. The
+purpose of this project was to study the effects of SEM-imaging on GO films.
+Using an SEM, we irradiated GO samples at electron beam-energies of 10, 20, and
+30 keV (at a constant emission current of ~40 micro-amps) for times ranging
+from 15 minutes to one hour. Raman D- and G-band intensities were used to
+examine structural modifications/damage to GO samples as a function of beam
+energy and exposure time. The results suggest that imaging with a 30 keV
+electron beam for 30 minutes may lead to the formation of amorphous carbon,
+while imaging with 10 keV or 20 keV beams for 30 minutes does not have a
+significant effect on GO samples.",1907.06311v1
+2019-07-17,Low-frequency charge noise in Si/SiGe quantum dots,"Electron spins in silicon have long coherence times and are a promising qubit
+platform. However, electric field noise in semiconductors poses a challenge for
+most single- and multi-qubit operations in quantum-dot spin qubits. Here, we
+investigate the dependence of low-frequency charge noise spectra on temperature
+and aluminum-oxide gate dielectric thickness in Si/SiGe quantum dots with
+overlapping gates. We find that charge noise increases with aluminum oxide
+thickness. We also find strong dot-to-dot variations in the temperature
+dependence of the noise magnitude and spectrum. These findings suggest that
+each quantum dot experiences noise caused by a distinct ensemble of two-level
+systems, each of which has a non-uniform distribution of thermal activation
+energies. Taken together, our results suggest that charge noise in Si/SiGe
+quantum dots originates at least in part from a non-uniform distribution of
+two-level systems near the surface of the semiconductor.",1907.07549v3
+2019-07-17,Novel Receiver for Superparamagnetic Iron Oxide Nanoparticles in a Molecular Communication Setting,"Superparamagnetic iron oxide nanoparticles (SPIONs) have recently been
+introduced as information carriers in a testbed for molecular communication
+(MC) in duct flow. Here, a new receiver for this testbed is presented, based on
+the concept of a bridge circuit. The capability for a reliable transmission
+using the testbed and detection of the proposed receiver was evaluated by
+sending a text message and a 80 bit random sequence at a bit rate of 1/s, which
+resulted in a bit error rate of 0 %. Furthermore, the sensitivity of the device
+was assessed by a dilution series, which gave a limit for the detectability of
+peaks between 0.1 to 0.5 mg/mL. Compared to the commercial susceptometer that
+was previously used as receiver, the new detector provides an increased
+sampling rate of 100 samples/s and flexibility in the dimensions of the
+propagation channel. Furthermore, it allows to implement both single-ended and
+differential signaling in SPION-bases MC testbeds.",1907.07805v1
+2019-07-23,Interfacial phenomena in nanocapacitors with multifunctional oxides,"The analysis of the structure, chemical stability, electronic and
+ferroelectric properties of the interfaces between Pt(001) and PbZrTiO$_3$(001)
+(PZT) have been performed with $ab$ $initio$ methods. We show that the chemical
+environment plays a critical role in determining the interfacial reconstruction
+and charge redistribution at the metal/oxide interfaces. We demonstrate that
+the difference in interfacial bonds formed at the Pt/PZT interfaces with
+(TiZr)O$_2$ - and PbO- termination of PZT essentially defines the effectiveness
+of the screening, and ease of polarisation switching in PZT-based capacitors.
+The imperfect screening in Pt/PZT/Pt capacitors is caused by strong interfacial
+bonds formed at the interface with (TiZr)O$_2$-terminated film, which is
+accompanied by the suppressed polarisation of PZT film. In contrast, the
+capacitors with PbO-terminated PZT show a negligible depolarising field and
+high polarisation, which is the consequence of weak bonds formed at this type
+of interfaces. The latter also causes a higher switching barrier than that in
+the former system.",1907.09821v1
+2019-07-24,Systematic beyond-DFT study of binary transition metal oxides,"Various methods going beyond density-functional theory (DFT), such as DFT+U,
+hybrid functionals, meta-GGAs, GW, and DFT-embedded dynamical mean field theory
+(eDMFT), have been developed to describe the electronic structure of correlated
+materials, but it is unclear how accurate these methods can be expected to be
+when applied to a given strongly correlated solid. It is thus of pressing
+interest to compare their accuracy as they apply to different categories of
+materials. Here, we introduce a novel paradigm in which a chosen set of
+beyond-DFT methods is systematically and uniformly tested on a chosen class of
+materials. For a first application, we choose the target materials to be the
+binary transition-metal oxides FeO, CoO, MnO, and NiO in their
+antiferromagnetic phase and present a head-to-head comparison of spectral
+properties as computed using the various methods. We also compare with
+available experimental angle-resolved photoemission spectroscopy (ARPES),
+inverse-photoemission spectroscopy, and with optical absorption. We find both
+B3LYP and eDMFT can reproduce the experiments quite well, with eDMFT doing best
+in particular when comparing with the ARPES data.",1907.10498v1
+2019-07-29,Air tightness of hBN encapsulation and its impact on Raman spectroscopy of van der Waals materials,"Raman spectroscopy is a precious tool for the characterization of van der
+Waals materials, e.g. for the determination of the layer number in thin
+exfoliated flakes. For sensitive materials, however, this method can be
+dramatically invasive. In particular, the light intensity required to obtain a
+significant Raman signal is sufficient to immediately photo-oxidize few-layer
+thick metallic van der Waals materials. In this work we investigated the impact
+of the environment on Raman characterization of thin NbSe$_2$ crystals. We show
+that in ambient conditions the flake is locally oxidized even for very low
+illumination intensity. On the other hand, we observe no degradation if the
+Raman measurements are performed either in vacuum or on fully hBN-encapsulated
+samples. Interestingly, we find that covering samples deposited on the usual
+SiO$_2$ surface only from the top is not sufficient to prevent diffusion of
+oxygen underneath the layers.",1907.12265v1
+2019-07-30,Influence of Local Defects on the Dynamics of O-H Bond Breaking and Formation on a Magnetite Surface,"The transport of H adatoms across oxide supports plays an important role in
+many catalytic reactions. We investigate the dynamics of H/Fe3O4(001) between
+295 and 382 K. By scanning tunneling microscopy at frame rates of up to 19.6
+fps, we observe the thermally activated switching of H between two O atoms on
+neighboring Fe rows. This switching rate changes in proximity to a defect,
+explained by density functional theory as a distortion in the Fe-O lattice
+shortening the diffusion path. Quantitative analysis yields an apparent
+activation barrier of 0.94 +/- 0.07 eV on a pristine surface. The present work
+highlights the importance of local techniques in the study of atomic-scale
+dynamics at defective surfaces such as oxide supports.",1907.12944v1
+2019-07-30,Optical properties of mist CVD grown $α$-Ga$_2$O$_3$,"We report on the study of optical properties of mist CVD grown alpha Gallium
+oxide with the observation of excitonic absorption in spectral responsivity
+measurements. 163 nm of Gallium oxide was grown on sapphire using Gallium
+acetylacetonate as the starting solution at a substrate temperature of 450 deg
+C. The film was found to be crystalline and of alpha phase with an on axis full
+width at half maximum of 92 arcsec as confirmed from X ray diffraction scans.
+The Taucs plot extracted from absorption spectroscopy exhibited two transitions
+in the UV regime at 5.3 eV and 5.6 eV, corresponding to excitonic absorption
+and direct band to band transition respectively. The binding energy of exciton
+was extracted to be 114 meV from spectral responsivity measurements. Further,
+metal semiconductor metal photodetectors with lateral inter digitated geometry
+were fabricated on the film. A sharp band edge was observed at 230 nm in the
+spectral response with peak responsivity of around 1 Amperes per Watt at a bias
+of 20 V. The UV to visible rejection ratio was found to be around 100 while the
+dark current was measured to be around 0.1 nA.",1907.13072v1
+2019-07-31,Limitations of In$_2$O$_3$ as a transparent conducting oxide,"Sn-doped In$_2$O$_3$ or ITO is the most widely used transparent conducting
+oxide. We use first-principles calculations to investigate the limitations to
+its transparency due to free-carrier absorption mediated by phonons or charged
+defects. We find that the main contribution to the phonon-assisted indirect
+absorption is due to emission (as opposed to absorption) of phonons, which
+explains why the process is relatively insensitive to temperature. The
+wavelength dependence of this indirect absorption process can be described by a
+power law. Indirect absorption mediated by charged defects or impurities is
+also unavoidable since doping is required to obtain conductivity. At high
+carrier concentrations, screening by the free carriers becomes important. We
+find that charged-impurity-assisted absorption becomes larger than
+phonon-assisted absorption for impurity concentrations above 10$^{20}$
+cm$^{-3}$. The differences in the photon-energy dependence of the two processes
+can be explained by band-structure effects.",1907.13573v1
+2019-09-04,"Effect of annealing on the structural, topographical and optical properties of sol gel derived ZnO and AZO thin films","A comparative study of the physical properties of undoped Zinc Oxide (ZnO)
+and Al doped Zinc Oxide (AZO) thin films were performed as a function of
+annealing temperature. The structural properties were analyzed using X-ray
+diffraction and the recorded patterns indicated that the crystallinity of the
+films always enhanced with increasing annealing temperature while it degrades
+with Al doping. The topographical modification of the films due to heat
+treatment was examined by atomic force microscopy which revealed that annealing
+roughened the surface of all the films; however the AZO films always exhibited
+smoother morphology than ZnO. Study of the optical properties by UV-Visible
+spectrophotometer demonstrated that the transmittance was gradually diminished
+with the rise in annealing temperature. In addition, a notable increase in the
+optical band gap was also observed for the AZO films.",1909.01987v1
+2019-09-23,Superstatistical approach to air pollution statistics,"Air pollution by Nitrogen Oxides (NOx) is a major concern in large cities as
+it has severe adverse health effects. However, the statistical properties of
+air pollutants are not fully understood. Here, we use methods borrowed from
+nonequilibrium statistical mechanics to construct suitable superstatistical
+models for air pollution statistics. In particular, we analyze time series of
+Nitritic Oxide ($NO$) and Nitrogen Dioxide ($NO_2$) concentrations recorded at
+several locations throughout Greater London. We find that the probability
+distributions of concentrations have heavy tails and that the dynamics is
+well-described by $\chi^2$ superstatistics for $NO$ and inverse $\chi^2$
+superstatistics for $NO_2$. Our results can be used to give precise risk
+estimates of high-pollution situations and pave the way to mitigation
+strategies.",1909.10433v2
+2019-09-23,Nanostructured La0.5Ba0.5CoO3 as cathode for solid oxide fuel cells,"A simple method has been used to synthesize nanostructured La0.5Ba0.5CoO3
+(LBCO) powders, by confining chemical precursors into the pores of
+polycarbonate filters. The proposed method allows us to obtain powders formed
+by crystallites of different sizes, it is scalable and does not involve the use
+of sophisticated deposition techniques. The area specific polarization
+resistance of symmetrical cells was studied to analyze the electrochemical
+behavior of the LBCO nanostructures as cathodes for Solid-Oxide Fuel Cells. We
+show that the performance is improved by reducing the size of the crystallites,
+obtaining area specific resistance values of 0.2 Wcm2 at 700C, comparable with
+newly developed cathodes using novel deposition techniques.",1909.10611v1
+2019-10-03,Temperature-programmed reduction and dispersive X-ray absorption spectroscopy studies of CeO2-based nanopowders for intermediate-temperature Solid-Oxide Fuel Cell anodes,"In this work, we study the influence of the average crystallite size and
+dopant oxide on the reducibility of CeO2-based nanomaterials. Samples were
+prepared from commercial Gd2O3-, Sm2O3- and Y2O3-doped CeO2 powders by
+calcination at different temperatures ranging between 400 and 900C and
+characterized by X-ray powder diffraction, transmission electron microscopy and
+BET specific surface area. The reducibility of the samples was analyzed by
+temperature-programmed reduction and in situ dispersive X-ray absorption
+spectroscopy techniques. Our results clearly demonstrate that samples treated
+at lower temperatures, of smallest average crystallite size and highest
+specific surface areas, exhibit the best performance, while Gd2O3-doped ceria
+materials display higher reducibility than Sm2O3- and Y2O3-doped CeO2.",1910.01715v1
+2019-10-09,Antimony doped Tin Oxide/Polyethylenimine Electron Selective Contact for reliable and light soaking-free high Performance Inverted Organic Solar Cells,"We have demonstrated a high-performance low temperature solution processed
+electron selective contact consisting of 10 at% antimony doped tin oxide (ATO)
+and the neutral polymer polyethylenimine (PEI). Inverted organic photovoltaics
+(OPVs) utilizing ATO/PEI as electron selective contact exhibited high power
+conversion efficiencies for both the reference P3HT: PCBM and the non-fullerene
+based P3HT- IDTBR active layer OPV material systems. Importantly it is shown
+that the proposed ATO/PEI carrier selective contact provides light soaking-free
+inverted OPVs. Furthermore, by increasing the thickness of ATO layer from 40 to
+120 nm the power conversion efficiency of the corresponding inverted OPVs
+remain unaffected a parameter which indicates the potential of the proposed
+ATO/PEI carrier selective contact for high performance light-soaking-free and
+reliable roll-to-roll printing solutions processed inverted OPVs.",1910.04017v1
+2019-10-19,"Investigation of structural, electrical and electrochemical properties of La0.6Sr0.4Fe0.8Mn0.2O3-δ as an intermediate temperature solid oxide fuel cell cathode","La0.6Sr0.4Fe0.8Mn0.2O3 (LSFM) compound is synthesized by Sol-gel method and
+evaluated as a cathode material for the intermediate temperature solid oxide
+fuel cell (IT-SOFC). X-ray diffraction (XRD) indicates that the LSFM has a
+Rhombohedral structure with R-3c space group symmetry. The XRD patterns reveal
+very small amount of impurity phase in the LSFM and Y2O3-Stabilized ZrO2 (YSZ)
+mixture powders sintered at 600, 700 and 800 C for a week. The maximum
+electrical conductivity of LSFM is about 35.35 S.cm-1 at 783 C in the air. The
+oxygen chemical diffusion coefficients, DChem, are increased from 1.39*10-6 up
+to 7.66*10-6 .cm2. Besides, the oxygen surface exchange coefficients, kChem,
+are obtained to lie between 2.9*10-3 and 8.7*10-3 cm.s-1 in a temperature range
+of 600-800 C. The area-specific resistances (ASRs) of the LSFM symmetrical cell
+are 7.53, 1.53, 1.13, 0.46 and 0.31 .cm2 at 600, 650, 700, 750 and 800 C
+respectively, and related activation energy, Ea, is about 1.23 eV.",1910.08754v1
+2019-10-22,Negative thermal expansion of nanoporous anodic aluminum oxide membranes,"We have measured the thermal expansion of Ni nanowires electrodeposited into
+self-organized nanoporous amorphous aluminum oxide (AAO) membranes without Al
+substrate using X-ray diffraction between 110K and 350K. The results indicate
+an average thermal expansion of the Ni nanowires -- along the wire axis -- of
+$\langle\alpha\rangle_{\rm NiNW}=-(1.6 \pm 1.5)\times 10^{-6}$/K. Assuming a
+bulk-like thermal expansion of the isolated Ni nanowires, this result indicates
+that AAO has also a negative thermal expansion. We estimate the thermal
+expansion of nanoporous AAO to be $\langle\alpha\rangle_{\rm AAO}=-(5 \pm 1)
+\times 10^{-6}$/K. We show that data obtained previously on the thermal
+expansion of metallic nanowires grown in the nanoporous AAO may be interpreted
+as originated in a negative thermal expansion of the matrix.",1910.11190v1
+2019-10-30,Broadband and wide-temperature-range thermal emitter with super-hydrophobicity based on oxidized high-entropy film,"This paper demonstrates broadband and wide-temperature-range thermal emitter
+with super-hydrophobicity based on an oxidized high-entropy film. The annealed
+(NiCuCrFeSi)O high-entropy film can serve as a mid-infrared emitter due to its
+three characteristics: i) High blackbody-like emission in a broadband
+mid-infrared region from 2.5 um to 20 um; ii) High emittance (more than 90%) in
+a wide temperature range from 300 K to 1000 K; iii) Super-hydrophobicity with
+high contact angle (CA) of 151 degree and low title angle (TA) of 5 degree.
+These characteristics originate from the recrystallization of as-deposited film
+and formation of cavernous structure with a plethora of nanoscale polyhedrons
+and holes after an annealing process, supported by the results of XRD and
+SEM/EDX. This work may provide new ideas for applications of thermal emitters
+operating at substantially wide temperature range.",1910.13629v1
+2020-01-01,Mobile Small Polarons Explain Conductivity in Lithium Titanium Oxide Battery Electrodes,"Lithium titanium oxide Li$_4$Ti$_5$O$_{12}$ (LTO) is an intriguing anode
+material promising particularly long lived batteries, due to its remarkable
+phase stability during (dis)charging of the cell. However, its usage is limited
+by its low intrinsic electronic conductivity. Introducing oxygen vacancies can
+be one method to overcome this drawback, possibly by altering the charge
+carrier transport mechanism. We use Hubbard corrected density-functional theory
+(DFT+U) to show that polaronic states in combination with a possible hopping
+mechanism can play a crucial role in the experimentally observed increase of
+electronic conductivity. To gauge polaronic charge mobility, we compute
+relative stabilities of different localization patterns and estimate polaron
+hopping barrier heights. With this we finally show how defect engineering can
+indeed raise the electronic conductivity of LTO up to the level of its ionic
+conductivity, thereby explaining first experimental results for reduced LTO.",2001.00263v1
+2020-01-02,Molecular Patterning and Directed Self-Assembly of Gold Nanoparticles on GaAs,"The ability to create micro/nano patterns of organic self-assembled
+monolayers on semiconductor surfaces is crucial for fundamental studies and
+applications in a number of emerging fields in nanoscience. Here, we
+demonstrate the patterning of thiol molecular SAMs on oxide-free GaAs surface
+by dip-pen nanolithography and micro-contact printing, facilitated by a process
+of surface etching and passivation of the GaAs. A quantitative analysis on the
+molecular diffusion on GaAs was conducted by examining the writing of nanoscale
+dot and line patterns by DPN, which agrees well with surface diffusion models.
+The functionality of the patterned thiol molecules was demonstrated by directed
+self-assembly of gold nanoparticles onto a template of 4-Aminothiophenol SAM on
+GaAs. The highly selective assembly of the Au NPs was evidenced with atomic
+force microscopy and scanning electron microscopy. The ability to precisely
+control the assembly of Au NPs on oxide-free semiconductor surfaces using
+molecular templates may lead to an efficient bottom-up method for the
+fabrication of nano-plasmonic structures.",2001.00592v1
+2020-01-08,Influence of doping on the properties of vanadium oxide gel films,"Effect of doping with H and W on the properties of V2O5 and VO2 derived from
+V2O5 gel has been studied. It is shown that the treatment of V2O5 in
+low-temperature RF hydrogen plasma for 1 to 10 min. leads to either hydration
+of vanadium pentoxide or its reduction (depending on the treatment conditions)
+to lower vanadium oxides. For some samples, which are subject to plasma
+treatment in the discharge active zone, a non-ordinary temperature dependence
+of resistance, with a maxi-mum at T ~ 100 K, is observed. For W-doped VO2
+films, it is shown that substitution of V4+ with W6+ results in a decrease of
+the temperature of metal-insulator transition. Also, it has been shown that the
+doping of the initial films with ~3 at.% of W reduces the statistical scatter
+in the thresh-old parameters of the switching devices with S-shaped I-V
+characteristics on the basis of V2O5 gel films.",2001.02402v1
+2020-01-08,Effect of memory electrical switching in metal/vanadium oxide/silicon structures with VO2 films obtained by the sol-gel method,"Electrical switching and rectifying properties of the metal-VO2-Si
+structures, on both p-type and n-type silicon, with vanadium dioxide films
+obtained by an acetylacetonate sol-gel method, are studied. The switching
+effect is shown to be due to the semiconductor-to-metal phase transition (SMPT)
+in vanadium dioxide. The shift of the switching threshold voltage, accompanied
+by the memory effect, in forward bias of the p-Si-VO2 anisotype heterojunction
+is observed. To explain this effect, a model is proposed which suggests the
+existence of an additional series resistance associated with a channel at the
+VO2/Si interface, where a SiOx layer forms during the VO2 deposition process.
+This resistance is responsible for both threshold switching characteristics,
+and the memory effect, and the oxygen ion electromigration process is shown to
+underlie this effect. Potential applications of the observed phenomena,
+combining the effects of ReRAM and SMPT, in oxide electronics are discussed.",2001.03055v1
+2020-01-25,"Prediction of perovskite-related structures in ACuO$_{3-x}$ (A $=$ Ca, Sr, Ba, Sc, Y, La) using density functional theory and Bayesian optimization","Oxygen vacancy ordering in perovskite-type transition-metal oxides plays an
+important role in the emergence of exotic electronic properties, as typified by
+superconducting cuprates. In this study, we predict the stability of
+oxygen-deficient perovskite structures in ACuO$_{3-x}$ (A $=$ Ca, Sr, Ba, Sc,
+Y, La) by density functional theory calculation. We introduce a combination of
+the cluster expansion method, Gaussian process, and Bayesian optimization to
+find stable oxygen-deficient structures among a considerable number of
+candidates. Our calculations not only reproduce the reported structures but
+suggest the presence of several unknown oxygen-deficient perovskite structures,
+some of which are stabilized at high pressures. This work demonstrates the
+great applicability of the present computational procedure for the elucidation
+of the structural stability of strongly correlated oxides with a large
+tolerance to oxygen deficiency.",2001.09312v1
+2020-02-03,Actinide and Lanthanide Dioxide Lattice Dilatation Mechanisms with Defect Ingrowth,"{\alpha}-particle irradiated single-crystal isostructural oxide lattices
+(CmO2, AmO2, CeO2, UO2, NpO2, PuO2, ThO2) were modeled by molecular dynamics
+simulation method. Lattice parameter changes with IFP cation defects displayed
+exponential increases. These data were compatible with the available lattice
+parameter changes with {\alpha}-particle dose experiments. Pre- and post- peaks
+emerged around principal peaks of irradiated oxide cation-cation radial
+distribution functions, which indicate obstruction and distortion type defects,
+respectively. Dependence of lattice dilatations on the number of obstruction
+type cation defects was examined. In a previous study, obstruction type uranium
+defects were found to be directly responsible for the UO2 lattice swelling and
+there was a linear relationship between them. It was also determined that this
+linear equation has two different slopes at low and high defect concentrations.
+In this paper, it was found that these phenomena were not specific to UO2 and
+applicable to all fluorite-structured actinide and lanthanide dioxides studied
+here. These findings provide clues about the existence of more general law.",2002.00574v1
+2020-02-06,Durability of solid oxide electrolysis stack under dynamic load cycling for syngas production,"A 6-cell solid oxide electrolysis stack was tested under H2O + CO2
+co-electrolysis conditions. The cells used in the stack consisted of a
+nickel-yttria stabilized zirconia (Ni-YSZ) fuel electrode, YSZ electrolyte and
+lanthanum strontium cobaltite-gadolinium doped ceria (LSC-GDC) composite oxygen
+electrode. The aim of this study was to investigate the stack durability when
+operated under dynamic load conditions simulating a wind energy powered SOEC
+stack for synthesis gas production. The degradation of the stack was observed
+to be less than 1%/1000 h in terms of area specific resistance during the 1000
+hours operation. Detailed electrochemical analysis revealed a constant ohmic
+resistance, indicating intact contact in the stack. Only minor degradation was
+observed, mainly due to the fuel electrode process. The overall stack voltage
+degradation rate was 0.8%/1000 h.",2002.02169v1
+2020-02-06,Quantized Auger Recombination of Polaronic Self-trapped Excitons in Bulk Iron Oxide,"The Auger recombination in bulk semiconductors can depopulate the charge
+carriers in a non-radiative way, which, fortunately, only has detrimental
+impact on optoelectronic device performance under the condition of high carrier
+density because the restriction arising from concurrent momentum and energy
+conservation limits the Auger rate. Here, we surprisingly found that the Auger
+recombination in bulk Fe2O3 films was more efficient than narrow-bandgap
+high-mobility semiconductors that were supposed to have much higher Auger rate
+constants than metal oxides. The Auger process in Fe2O3 was ascribed to the
+Coulombically coupled self-trapped excitons (STEs), which was enhanced by the
+relaxation of momentum conservation because of the strong spatial localization
+of these STEs. Furthermore, due to this localization effect the kinetic traces
+of the STE annihilation for different STE densities exhibited characteristics
+of quantized Auger recombination, and we demonstrated that these traces could
+be simultaneously modeled by taking into account the quantized Auger rates.",2002.02389v1
+2020-02-12,Green exciton series in cuprous oxide,"We numerically investigate the odd parity states of the green exciton series
+in cuprous oxide. Taking into account the coupling to the yellow series and
+especially to the yellow continuum, the green excitons are quasi-bound
+resonances with a finite lifetime which cannot be described with Hermitian
+operators. To calculate their positions and linewidths, we use the method of
+complex-coordinate rotation, leading to a non-Hermitian complex eigenvalue
+problem. We find that the behavior of the dominant P states is very well
+approximated by a modified Rydberg formula using a negative quantum defect. The
+corresponding linewidths induced by the coupling to the yellow continuum
+decrease with the third power of the principal quantum number.",2002.04973v1
+2020-02-17,Color Tuning by Spontaneous Propagation of Gap Surface Plasmons in Epsilon Near Zero Nano-Cavity,"This work presents numerical and experimental results of plasmonic
+Metal-Insulator optical nano-cavities. The systems are composed of Silver as
+metal, polyvinylpyrrolidone or indium tin oxide or zinc oxide as insulator. The
+proposed nano-cavities exhibit extraordinary effects as colors changing in
+function of the incident/view angles, enhancement of the experimental real and
+imaginary parts of the pseudo dielectric constant, an extraordinary
+transmission of 50$\%$ and zero reflection for both polarizations at the
+resonant wavelengths. These results lead to the formation and propagation of
+surface plasmon polaritons and their hybridization in gap surface plasmons. The
+concurrence of these effects allow studying the Goos-H\""anchen shift by
+exploiting the very narrow $\Delta$ and $\Psi$ ellipsometer parameters. Thank
+to their optical properties, the proposed nano-cavities could be applied in
+several fields such tunable color filters, optics, photonics and sensing.",2002.06972v1
+2019-12-29,Bioinspired Nanocomposites: 2D Materials Within a 3D Lattice,"Advanced composites are used in a variety of industrial applications and
+therefore attract much scientific interest. Here we describe the formation of
+novel carbon-based nanocomposites via incorporation of graphene oxide into the
+crystal lattice of single crystals of calcite. Incorporation of a 2D organic
+material into single-crystal lattices has never before been reported. To
+characterize the resulting nanocomposites we employed high-resolution
+synchrotron powder X-ray diffraction, electron microscopy, transmission
+electron microscopy, fluorescence microscopy, and nanoindentation tests.
+Detailed analysis revealed a layered distribution of graphene oxide sheets
+incorporated within the calcite host. Moreover, the optical and mechanical
+properties of the calcite host were altered when a carbon-based nanomaterial
+was introduced into its lattice. Compared to pure calcite, the composite
+GO-calcite crystals exhibited lower elastic modulus and higher hardness. The
+results of this study show that the incorporation of a 2D material within a 3D
+crystal lattice is not only feasible but also can lead to the formation of
+hybrid crystals exhibiting new properties.",2002.07059v1
+2020-02-25,Antiferroelectricity in a family of pyroxene-like oxides with rich polymorphism,"Antiferroelectrics have potential applications in energy conversion and
+storage, but are scarce, particularly among oxides that otherwise display rich
+ferroic behaviours. Are we overlooking potential antiferroelectrics, simply
+because we have not discovered their corresponding ferroelectric phase yet?
+Here we report a first-principles study suggesting this is the case of a family
+ABO$_3$ pyroxene-like materials, characterized by chains of corner-sharing
+BO$_4$ tetrahedra, a well-known member being KVO$_3$. The irregular tetrahedra
+have an electric dipole associated to them. In the most stable polymorph, the
+dipoles display an antipolar pattern with zero net moment. However, upon
+application of an electric field, half of the tetrahedra rotate, flipping the
+corresponding dipoles and reaching a ferroelectric state. We discuss the unique
+possibilities for tuning and optimization these antiferroelectrics offer. We
+argue that the structural features enabling this antiferroelectric behaviour
+are also present in other all-important mineral families.",2002.11120v1
+2020-02-26,Stressor-Layer-Induced Elastic Strain Sharing in SrTiO3 Complex Oxide Sheets,"A precisely selected elastic strain can be introduced in submicron-thick
+single-crystal SrTiO3 sheets using a silicon nitride stressor layer. A
+conformal stressor layer deposited using plasma-enhanced chemical vapor
+deposition produces an elastic strain in the sheet consistent with the
+magnitude of the nitride residual stress. Synchrotron x-ray nanodiffraction
+reveals that the strain introduced in the SrTiO3 sheets is on the order of 10
+4, matching the predictions of an elastic model. This approach to elastic
+strain sharing in complex oxides allows the strain to be selected within a wide
+and continuous range of values, an effect not achievable in heteroepitaxy on
+rigid substrates.",2002.11287v1
+2020-02-26,Effect of lattice distortions on the electron and thermal transport properties of transparent oxide semiconductor Ba1-xSrxSnO3 solid solution films,"La-doped ASnO3 (A = Ba, Sr) have great potential as advanced transparent
+oxide semiconductors due to their large optical bandgap and relatively high
+electron mobility. The bandgap of Ba1-xSrxSnO3 solid solution increases from
+3.2 eV (BaSnO3) to 4.6 eV (SrSnO3) with x. However, the increase in the bandgap
+is accompanied by reductions in the electrical conductivity. The versatility in
+the changes in the electrical properties are not trivial, and the property
+optimization has been challenging. Here we propose a simple metric for
+quantifying the transport properties of ASnO3. We investigated the
+electron/thermal transport properties of Ba1-xSrxSnO3 solid solution films and
+their relationship with the lattice distortion. The results suggest that the
+all transport properties of Ba1-xSrxSnO3 are dominated by the lattice
+distortion. This phenomenon is attributed to the distortions in the SnO6
+octahedron, which consists the conduction band.",2002.11308v1
+2020-04-02,Device-aware inference operations in SONOS nonvolatile memory arrays,"Non-volatile memory arrays can deploy pre-trained neural network models for
+edge inference. However, these systems are affected by device-level noise and
+retention issues. Here, we examine damage caused by these effects, introduce a
+mitigation strategy, and demonstrate its use in fabricated array of SONOS
+(Silicon-Oxide-Nitride-Oxide-Silicon) devices. On MNIST, fashion-MNIST, and
+CIFAR-10 tasks, our approach increases resilience to synaptic noise and drift.
+We also show strong performance can be realized with ADCs of 5-8 bits
+precision.",2004.00802v1
+2020-03-03,Tunable capacitance in all-inkjet-printed nanosheet heterostructures,"Heterostructures constructed from two-dimensional building blocks have shown
+promise for field-effect transistors, memory devices, photosensors and other
+electronic applications1,2. 2D nanosheet crystals can be constructed into
+multilayer heterostructures using layer-by-layer methods3, but that method
+cannot be used to fabricate large-scale and thick heterostructures, due to the
+time-consuming nature and low efficiency of the process. An alternative
+approach to deposit different two-dimensional materials is by inkjet
+printing4-7. Here we show the fabrication of a nanosheet supercapacitor by
+inkjet printing Ti3C2Tx MXene nanosheets as electrodes, and graphene oxide
+nanosheets as solid-state electrolyte. The free water molecules trapped between
+graphene oxide sheets facilitate proton movement through the layered solid
+electrolyte8. The as-made supercapacitor shows high areal capacitance, good
+cycling stability and high areal energy and power densities comparable with
+existing printed supercapacitors. Moreover, the specific capacitance can be
+increased further by addition of liquid electrolytes.",2004.03350v1
+2020-04-09,Double photoionization of propylene oxide: a coincidence study of the ejection of a pair of valence-shell electrons,"Propylene oxide, a favorite target of experimental and theoretical studies of
+circular dichroism, was recently discovered in interstellar space, further
+amplifying the attention to its role in the current debate on protobiological
+homochirality. In the present work, a photoelectron-photoion-photoion
+coincidence technique, using an ion-imaging detector and tunable synchrotron
+radiation in the 18.0-37.0 eV energy range, permits: (i)-to observe six
+double-ionization fragmentation channels, their relative yields being accounted
+for about two-thirds by the couple (C2H4+, CH2O+), one-fifth by (C2H3+, CH3O+);
+(ii)-to measure thresholds for their openings as a function of photon energy;
+(iii)-to unravel a pronounced bimodality for a kinetic-energy-released
+distribution, fingerprint of competitive non-adiabatic mechanisms.",2004.04639v1
+2020-04-30,Precision Spectroscopy of Nitrous Oxide Isotopocules with a Cross-Dispersed Spectrometer and Mid-Infrared Frequency Comb,"As a potent greenhouse gas and ozone depleting agent, nitrous oxide (N$_2$O)
+plays a critical role in the global climate. Effective mitigation relies on
+understanding global sources and sinks which can be supported through isotopic
+analysis. We present a cross-dispersed spectrometer, coupled with a
+mid-infrared frequency comb, capable of simultaneously monitoring all singly
+substituted, stable isotopic variants of N$_2$O. Rigorous evaluation of the
+instrument lineshape function and data treatment are discussed. Laboratory
+characterization of the spectrometer demonstrates sub-GHz spectral resolution
+and an average precision of $7.4\times10^{-6}$ for fractional isotopic
+abundance retrievals in 1 s.",2004.14962v1
+2020-12-02,High-temperature topological superconductivity in twisted double layer copper oxides,"A great variety of novel phenomena occur when two-dimensional materials, such
+as graphene or transition metal dichalcogenides, are assembled into bilayers
+with a twist between individual layers. As a new application of this paradigm,
+we consider structures composed of two monolayer-thin $d$-wave superconductors
+with a twist angle $\theta$ that can be realized by mechanically exfoliating
+van der Waals-bonded high-$T_c$ copper oxide materials, such as
+Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$. On the basis of symmetry arguments and
+detailed microscopic modelling, we predict that for a range of twist angles in
+the vicinity of $45^{\rm o}$, such bilayers form a robust, fully gapped
+topological phase with spontaneously broken time-reversal symmetry and
+protected chiral Majorana edge modes. When $\theta\approx 45^{\rm
+  o}$, the topological phase sets in at temperatures close to the bulk
+$T_c\simeq 90$ K, thus furnishing a long sought realization of a true
+high-temperature topological superconductor.",2012.01412v1
+2020-12-08,Empirical Analysis of the Photoelectrochemical Impedance Response of Hematite Photoanodes for Water Photo-Oxidation,"Photoelectrochemical impedance spectroscopy (PEIS) is a useful tool for the
+characterization of photoelectrodes for solar water splitting. However, the
+analysis of PEIS spectra often involves a priori assumptions that might bias
+the results. This work puts forward an empirical method that analyzes the
+distribution of relaxation times (DRT), obtained directly from the measured
+PEIS spectra of a model hematite photoanode. By following how the DRT evolves
+as a function of control parameters such as the applied potential and
+composition of the electrolyte solution, we obtain unbiased insights into the
+underlying mechanisms that shape the photocurrent. In a subsequent step, we fit
+the data to a process-oriented equivalent circuit model (ECM) whose makeup is
+derived from the DRT analysis in the first step. This yields consistent
+quantitative trends of the dominant polarization processes observed. Our
+observations reveal a common step for the photo-oxidation reactions of water
+and H2O2 in alkaline solution",2012.05081v1
+2020-12-17,High pressure computational search of trivalent lanthanide di-nitrides,"Transition metal nitrides have attracted much interest of the scientific
+community for their intriguing properties and technological applications. Here
+we focus on yttrium dinitride (YN$_{2}$) and its formation and structural
+transition under pressure. We employed a fixed composition USPEX search to find
+the most stable polymorphs. We choose yttrium as a proxy for the lanthanide
+series because it has only $+3$ oxidation state, contrary to most transition
+metals. We then computed thermodynamic and dynamical stability of these
+structures compared to the decomposition reactions and we found that the
+compound undergoes two structural transitions, the latter showing the formation
+N$_{4}$ chains. A closer look into the nature of the nitrogen bonding showed
+that in the first two structures, where nitrogen forms dimers, the bond length
+is intermediate between that of a single bond and that of a double bond, making
+it hard to rationalize the proper oxidation state configuration for YN$_{2}$.
+In the latter structure where there is the formation of N$_{4}$ chains, the
+bond lengths increase significantly, up to a value that can be justified as a
+single bond. Finally, we also studied the electronic structure and the
+dynamical stability of the structures we found.",2012.09576v1
+2020-12-22,Perovskite oxide heterojunction for Rashba-Dresselhaus assisted antiferromagnetic spintronics,"A major impediment towards realizing technologies based on the emerging
+principles of antiferromagnetic spintronics is the shortage of suitable
+materials. In this paper, we propose a design of polar|nonpolar
+heterostructures of perovskite oxides, where a single unit cell of SrIrO3 is
+sandwiched between a thin film of LaAlO3 and a substrate of SrTiO3. Our
+calculations within the framework of density-functional theory + Hubbard U +
+spin-orbit coupling reveal a two-dimensional conducting layer with electron and
+hole pockets at the interface, exhibiting a strong anisotropic
+Rashba-Dresselhaus effect along with noncollinear antiferromagnetism,
+indicating the possibility of realizing a spin-orbit torque. An insightful
+physical model for the anisotropic Rashba-Dresselhaus effect nicely interprets
+our results, providing an estimate for the Rashba-Dresselhaus coefficients and
+illustrating pseudospin orientation.We also observe a proximity-induced
+prominent Rashba-like effect for Ti 3d empty bands. Our results suggest that
+the heterostructure may possess the essential ingredients for antiferromagnetic
+spintronics, deserving experimental verification.",2012.11868v1
+2020-12-22,Dynamical heterogeneities in non-entangled polystyrene and poly(ethylene oxide) star melts,"Star polymers can exhibit a heterogeneous dynamical behavior due to their
+internal structure. In this work we employ atomistic molecular dynamics
+simulations to study translational motion in non-entangled polystyrene and
+poly(ethylene oxide) star-shaped melts. We focus on the local heterogeneous
+dynamics originating from the multi-arm star-like architecture and quantify the
+intramolecular dynamical gradient. By examining the translational motion at
+length scales of the order of the Kuhn length, we aim to find common features
+for both studied chemistries and to provide a critical and direct comparison
+with theoretical models of polymer dynamics. We discuss the observed tendencies
+with respect to the continuous Rouse model adjusted for the star-like
+architectures. Two versions of the Rouse model are examined: one assuming
+uniform friction on every Rouse bead and another one considering larger branch
+point friction. Apart from chain connectivity between neighboring beads, both
+versions disregard interactions between the chains. Despite the tolerable
+description of the simulation data, neither model appears to reflect the
+mobility gradient accurately. The detailed quantitative atomistic models
+employed here bridge the gap between the theoretical and general,
+coarse-granined models of star-like polymers which lack the indispensable
+chemical details.",2012.12333v1
+2020-12-30,Study of SiO2-PbO-CdO-Ga2O3 glass system for mid infrared optical elements,"Glasses based on SiO2-PbO-CdO-Ga2O3 system have been studied for the first
+time for fabrication of mid-infrared optical elements. Gallium oxide
+concentration was gradually increased, replacing silicon dioxide, for different
+cadmium and lead oxide content. The thermal and optical properties were
+investigated for different compositions. It was observed that the thermal
+stability, refractive index, and the transmission in the infrared range
+increased with increase of gallium and lead concentrations. The most thermally
+stable glass composition was selected for fabrication of optical elements such
+as optical fibers. We also successfully fabricated mid-infrared lenses by hot
+embossing for potential application in compact gas detectors",2012.15096v1
+2021-01-07,Optically Facet-Resolved Reaction Anisotropy in Two-Dimensional Transition Metal Dichalcogenides,"Quantifying anisotropy in the chemical reactions of mesoscopic crystals has
+mostly resorted on the combination of electron microscopy and diffraction. In
+this work, we established crystal-facet-resolved kinetic measurements of
+oxidation reactions in 2D transition metal dichalcogenides (TMDs) using optical
+second-harmonic generation spectroscopy and scanning probe microscopy. We show
+the in-plane anisotropy of their bond-breaking reactions is governed by their
+structure and strongly material-dependent among four TMDs. The facet-resolved
+analysis directly revealed that the reactions proceed fastest (slowest) for
+chalcogen (metal)-terminated zigzag edges with armchair edges in the middle.
+The degree of the anisotropy inducing trigonal oxidation patterns was much
+higher in MoS2 and MoSe2 than WS2 and WSe2. Kinetic Wulff construction based on
+edge-specific reaction rates verified the material-dependent mesoscopic
+reaction patterns. We also show that the reactions are initiated at
+substrate-mediated defects located on the bottom and top surfaces of 2D TMDs.",2101.02376v2
+2021-01-07,Automated coordination corrected enthalpies with AFLOW-CCE,"The computational design of materials with ionic bonds poses a critical
+challenge to thermodynamic modeling since density functional theory yields
+inaccurate predictions of their formation enthalpies. Progress requires
+leveraging physically insightful correction methods. The recently introduced
+coordination corrected enthalpies (CCE) method delivers accurate formation
+enthalpies with mean absolute errors close to room temperature thermal energy,
+i.e., 25meV/atom. The CCE scheme, depending on the number of cation-anion bonds
+and oxidation state of the cation, requires an automated analysis of the system
+to determine and apply the correction. Here, we present AFLOW-CCE -- our
+implementation of CCE into the AFLOW framework for computational materials
+design. It features a command line tool, a web interface and a Python
+environment. The workflow includes a structural analysis, automatically
+determines oxidation numbers, and accounts for temperature effects by
+parametrizing vibrational contributions to the formation enthalpy per bond.",2101.02724v2
+2021-01-09,Interface-Driven Thermo-Electric Switching Performance of VO$^+$ Diffused Soda-Lime Glass,"Strongly confined NaVO$^+$ segregation and its thermo-responsive
+functionality at the interface between simple sputter-deposited amorphous
+vanadium oxide thin films and soda-lime glass was substantiated in the present
+study by in-situ temperature-controlled Time of Flight Secondary Ion Mass
+Spectrometry (ToF-SIMS). The obtained ToF-SIMS depth profiles provided
+unambiguous evidence for a reversible transformation that caused systematic
+switching of the NaVO$^+$/ Na$^+$ and Na$^+$/ VO$^+$ intensities upon cycling
+the temperature between 25 $^\circ$C and 340 $^\circ$C. Subsequently, NaVO
+complexes were found to be reversibly formed (at 300 $^\circ$C) in vanadium
+oxide diffused glass, leading to thermo-responsive electrical behaviour of the
+thin film glass system. This new segregation -- and diffusion-dependent
+multifunctionality of NaVO$^+$ -- points towards applications as an advanced
+material for thermo-optical switches, in smart windows or in thermal sensors.",2101.03330v1
+2021-01-12,Magic Doping and Robust Superconductivity in Monolayer FeSe on Titanates,"The enhanced superconductivity in monolayer FeSe on titanates opens a
+fascinating pathway towards the rational design of high-temperature
+superconductors. Utilizing the state-of-the-art oxide plus chalcogenide
+molecular beam epitaxy systems in situ connected to a synchrotron
+angle-resolved photoemission spectroscope, epitaxial LaTiO3 layers with varied
+atomic thicknesses are inserted between monolayer FeSe and SrTiO3, for
+systematic modulation of interfacial chemical potential.With the dramatic
+increase of electron accumulation at the LaTiO3-SrTiO3 surface, providing a
+substantial surge of work function mismatch across the FeSe-oxide interface,
+the charge transfer and the superconducting gap in the monolayer FeSe are found
+to remain markedly robust. This unexpected finding indicates the existence of
+an intrinsically anchored magic doping within the monolayer FeSe systems.",2101.04787v1
+2021-01-20,Highly sensitive silver decorated-graphene oxide-silicon nanowires hybrid SERS sensors for trace level detection of environmental pollutants,"In this study, we evaluated the sensing performance of silver
+nanoprism/graphene oxide/silicon nanowires (AgNPr/GO/SiNWs) nanohybrid system
+for effective detection of organic dye and herbicide residues in freshwater via
+surface-enhanced Raman scattering (SERS). Homogenous and vertically aligned
+SiNWs have been successfully synthesized using metal-assisted chemical etching
+technique by varying the etching time from 10 to 30 min. AgNPr/GO/SiNW hybrids
+were assembled by spin-coating of GO followed by drop-casting deposition of
+AgNPr. The microstructures of AgNPr/GO/SiNWs are strongly affected by the
+etching time of SiNWs, which in turn affected its SERS performance when
+rhodamine 6G is used as an analyte molecule. Owing to the synergetic effects of
+GO and AgNPr, SERS response of AgNPr/GO/SiNWs composites were found to be
+superior compared to AgNPr/SiNWs. High efficiency of 6.1 x 1010 has been
+achieved with AgNPr/GO/SiNWs based sensor fabricated with 30-min etched SiNWs
+for rhodamine 6G. An effective way of rapid detection of drinking water
+pollutants such as methylene blue and atrazine up to picomolar (10-12 M)
+concentrations was demonstrated using these low-cost AgNPr/GO/SiNWs nanohybrids
+SERS sensors.",2101.07955v1
+2021-01-25,"A full configuration interaction quantum Monte Carlo study of ScO, TiO and VO molecules","Accurate ab initio calculations of 3d transition metal monoxide molecules
+have attracted extensive attention because of its relevance in physical and
+chemical science, as well as theoretical challenges in treating strong electron
+correlation. Meanwhile, recent years have witnessed the rapid development of
+full configuration interaction quantum Monte Carlo (FCIQMC) method to tackle
+electron correlation. In this study, we carry out FCIQMC simulations to ScO,
+TiO and VO molecules and obtain accurate descriptions of 13 low-lying
+electronic states (ScO $^2\Sigma^+$, $^2\Delta$, $^2\Pi$; TiO $^3\Delta$,
+$^1\Delta$, $^1\Sigma^+$, $^3\Pi$, $^3\Phi$; VO $^4\Sigma^-$, $^4\Phi$,
+$^4\Pi$, $^2\Gamma$, $^2\Delta$), including states that have significant
+multi-configurational character. The FCIQMC results are used to assess the
+performance of several other wave function theory and density functional theory
+methods. Our study highlights the challenging nature of electronic structure of
+transition metal oxides and demonstrates FCIQMC as a promising technique going
+forward to treat more complex transition metal oxide molecules and materials.",2101.09873v1
+2012-02-13,Nanostructured antimony tin oxide synthesized via chemical precipitation method: its characterization and application in humidity sensing,"In present investigation we report the synthesis of antimony tin oxide
+nanoparticles via chemical precipitation method. The synthesized material was
+characterized using X-ray diffractometer, Scanning Electron Microscope,
+UV-visible absorption spectroscopy. XRD shows the crystalline nature of the
+synthesized material and the crystallite size was estimated by using
+Debye-Scherer equation and its minimum value was 3 nm. Pelletization of
+synthesized material was done using hydraulic press machine under uniform
+pressure of 616 MPa. Then the pellets were annealed at 200, 400 and 600{\deg}C.
+Further each pellet was put in humidity sensing chamber and corresponding
+variations in resistance with relative humidity (%RH) were measured. The
+average sensitivity was calculated by taking the average of all sensitivities
+ranging from 10 to 90% RH. The average sensitivity of the pellet annealed at
+600{\deg}C was best among all the sensing pellets and was 2.18 K{\Omega}/%RH.
+Results were reproducible {\pm}84% after 2 months.",1205.2336v1
+2012-02-13,Temperature Sensors based on Semiconducting Oxides: An Overview,"Earlier studies show that organic and inorganic semiconducting materials are
+the most promising materials for use in temperature sensors. In this brief
+review, attention will be focused on temperature sensors and its applications
+in various fields. In addition, we have investigated the temperature sensing
+characteristics of nanostructured ZnO and ZnO-CuO nanocomposite. For this
+purpose, ZnO and ZnO-CuO nanocomposite were synthesized via chemical
+precipitation method. Scanning electron microscopy and X-ray diffraction of
+sensing materials have also performed. The average crystallite size was 45 and
+68 nm for ZnO and ZnO-CuO respectively. The pelletization of the synthesized
+powder was done using hydraulic pressing machine (MB Instrument, Delhi) under a
+pressure of 616 MPa at room ambient. This pellet was put within the
+Ag-Pellet-Ag electrode configuration for temperature sensing. Temperature
+sensitivities of above semiconducting oxides were calculated. Electrical
+properties of the materials establish the semiconducting nature of these
+sensing pellets. In addition, the activation energies of ZnO and ZnO-CuO
+nanocomposite were estimated.",1205.2712v1
+2012-05-16,Ab-initio Low-Energy Model of Transition-Metal-Oxide Heterostructure LaAlO3/SrTiO3,"We develop the multi-scale ab-initio scheme for correlated electrons (MACE)
+for transitionmetal-oxide heterostructures, and determine the parameters of the
+low-energy effective model. By separating Ti t2g bands near the Fermi level
+from the global Kohn-Sham (KS) bands of LaAlO3/SrTiO3 which are highly
+entangled with each other, we are able to calculate the parameters of the
+low-energy effective model of the interface with the help of constrained random
+phase approximation (cRPA). The on-site energies of the Ti t2g orbitals in the
+1stlayer is about 650 meV lower than those in the 2nd-layer. In the 1st-layer,
+the transfer integral of the Ti t2g orbital is nearly the same as that of the
+bulk SrTiO3, while the effective screened Coulomb interaction becomes about 10
+percent larger than that of the bulk SrTiO3. The differences of the parameters
+from the bulk SrTiO3 reduce rapidly with increasing distance from the
+interface. Our present versatile method makes it possible to derive effective
+ab-initio low-energy models and allows studying interfaces of strongly
+correlated electron systems from first principles.",1205.3600v1
+2012-05-31,Transfer-free Grown Bilayer Graphene Transistors for Digital Applications,"We invented a novel method to fabricate graphene transistors on oxidized
+silicon wafers without the need to transfer graphene layers. By means of
+catalytic chemical vapor deposition (CCVD) the in-situ grown bilayer graphene
+transistors (BiLGFETs) are realized directly on oxidized silicon substrate,
+whereby the number of stacked graphene layers is determined by the selected
+CCVD process parameters, e.g. temperature and gas mixture. BiLGFETs exhibit
+ultra-high on/off-current ratios of 107 at room temperature, exceeding
+previously reported values by several orders of magnitude. This will allow a
+simple and low-cost integration of graphene devices for digital nanoelectronic
+applications in a hybrid silicon CMOS environment for the first time.",1205.6909v1
+2017-05-05,Berezinskii-Kosterlitz-Thouless Type Scenario in Molecular Spin Liquid $A$Cr$_2$O$_4$,"The spin relaxation in chromium spinel oxides $A$Cr$_{2}$O$_{4}$ ($A=$ Mg,
+Zn, Cd) is investigated in the paramagnetic regime by electron spin resonance
+(ESR). The temperature dependence of the ESR linewidth indicates an
+unconventional spin-relaxation behavior, similar to spin-spin relaxation in the
+two-dimensional (2D) chromium-oxide triangular lattice antiferromagnets. The
+data can be described in terms of a generalized Berezinskii-Kosterlitz-Thouless
+(BKT) type scenario for 2D systems with additional internal symmetries. Based
+on the characteristic exponents obtained from the evaluation of the ESR
+linewidth, short-range order with a hidden internal symmetry is suggested.",1705.02234v1
+2017-05-01,Non Volatile MoS$_{2}$ Field Effect Transistors Directly Gated By Single Crystalline Epitaxial Ferroelectric,"We demonstrate non-volatile, n-type, back-gated, MoS$_{2}$ transistors,
+placed directly on an epitaxial grown, single crystalline,
+PbZr$_{0.2}$Ti$_{0.8}$O$_{3}$ (PZT) ferroelectric. The transistors show decent
+ON current (19 ${\mu}A/{\mu}$m), high on-off ratio (10$^{7}$), and a
+subthreshold swing of (SS ~ 92 mV/dec) with a 100 nm thick PZT layer as the
+back gate oxide. Importantly, the ferroelectric polarization can directly
+control the channel charge, showing a clear anti-clockwise hysteresis. We have
+selfconsistently confirmed the switching of the ferroelectric and corresponding
+change in channel current from a direct time-dependent measurement. Our results
+demonstrate that it is possible to obtain transistor operation directly on
+polar surfaces and therefore it should be possible to integrate 2D electronics
+with single crystalline functional oxides.",1705.03746v2
+2017-05-15,Theoretical insight into the interaction of O2 and H2O molecules with the perfect and the defective InSe monolayers,"By using first-principles calculation, the interaction of O2 and H2O
+molecules with the pristine and the defective InSe monolayers is studied. It is
+predicted that the single Se and In vacancies exhibit significantly enhanced
+chemical activity toward the adsorbates compared with the perfect InSe lattice
+site, and the Se vacancies have a much higher chemical activity than the In
+vacancies. H2O molecule should be only physisorbed on the various InSe
+monolayers at ambient conditions, according to the calculated energies. The
+doping of the various InSe monolayers is discussed by the physisorbed H2O. The
+vacancies show a much higher chemical activity toward O2 than H2O. Although O2
+molecules are still physisorbed on the pristine InSe monolayer, they will be
+chemisorbed on the defective InSe monolayers. Especially, our calculated
+energies suggest that the surface oxidation of the 2D InSe semiconductor should
+be dominated by the defects that expose under-coordinated host atoms,
+especially In atoms. Our theoretical results can help better understanding the
+doping and the oxidation of the 2D InSe semiconductor under ambient conditions.",1705.05140v1
+2017-05-16,Raman study of electron-phonon coupling in thin films of LiTi$_2$O$_4$ spinel oxide superconductor,"We performed a Raman scattering study of thin films of LiTi$_2$O$_4$ spinel
+oxide superconductor. We detected four out of five Raman active modes, with
+frequencies in good accordance with our first-principles calculations. Three
+T$_{2g}$ modes show a Fano lineshape from 5 K to 295 K, which suggests an
+electron-phonon coupling in LiTi$_2$O$_4$. Interestingly, the electron-phonon
+coupling shows an anomaly across the negative to positive magnetoresistance
+transition at 50 K, which may be due to the unset of other competing orders.
+The strength of the electron-phonon interaction estimated from the Allen's
+formula and the observed lineshape parameters suggests that the three T$_{2g}$
+modes contribute little to superconductivity.",1705.05568v1
+2017-05-16,Quantum Conductance Probing of Oxygen Vacancies in SrTiO3 Epitaxial Thin Film Using Graphene,"The quantum Hall conductance in monolayer graphene on an epitaxial SrTiO3
+(STO) thin film is studied to understand the role of oxygen vacancies in
+determining the dielectric properties of STO. As the gate voltage sweep range
+is gradually increased in our device, we observe systematic generation and
+annihilation of oxygen vacancies evidenced from the hysteretic conductance
+behavior in graphene. Furthermore, based on the experimentally observed linear
+scaling relation between the effective capacitance and the voltage sweep range,
+a simple model is constructed to manifest the relationship among the dielectric
+properties of STO with oxygen vacancies. The inherent quantum Hall conductance
+in graphene can be considered as a sensitive, robust, and non-invasive probe
+for understanding the electronic and ionic phenomena in complex transition
+metal oxides without impairing the oxide layer underneath.",1705.05672v1
+2017-05-16,Transition-Metal Oxide (111) bilayers,"Correlated electron systems on a honeycomb lattice have emerged as a fertile
+playground to explore exotic electronic phenomena. Theoretical and experimental
+work has appeared to realize novel behavior, including quantum Hall effects and
+valleytronics, mainly focusing on van der Waals compounds, such as graphene,
+chalcogenides, and halides. In this article, we review our theoretical study on
+perovskite transition-metal oxides (TMOs) as an alternative system to realize
+such exotic phenomena. We demonstrate that novel quantum Hall effects and
+related phenomena associated with the honeycomb structure could be artificially
+designed by such TMOs by growing their heterostructures along the [111]
+crystallographic axis. One of the important predictions is that such TMO
+heterostructures could support two-dimensional topological insulating states.
+The strong correlation effects inherent to TM $d$ electrons further enrich the
+behavior.",1705.05683v2
+2017-05-24,Multicomponent exciton gas in cuprous oxide: cooling behaviour and the role of Auger decay,"In this paper we present a hydrodynamic model to describe the dynamics of
+para- and orthoexcitons in cuprous oxide at ultralow temperatures inside a
+stress induced potential trap. We take into account the finite lifetime of the
+excitons, the excitation process and exciton-phonon as well as exciton-exciton
+interaction. Furthermore, we model the two-body loss mechanism assuming an
+Auger-like effect and compare it to an alternative explanation which relies on
+the formation of biexcitons. We discuss in detail the influence on the
+numerical results and compare the predictions to experimental data.",1705.08769v1
+2017-05-26,Observation of a two-dimensional electron gas at CaTiO$_3$ film surfaces,"The two-dimensional electron gas at the surface of titanates gathered
+attention due to its potential to replace conventional silicon based
+semiconductors in the future. In this study, we investigated films of the
+parent perovskite CaTiO$_3$, grown by pulsed laser deposition, by means of
+angular-resolved photoelectron spectroscopy. The films show a c(4x2) surface
+reconstruction after the growth that is reduced to a p(2x2) reconstruction
+under UV-light. At the CaTiO$_3$ film surface, a two-dimensional electron gas
+(2DEG) is found with an occupied band width of 400 meV. With our findings
+CaTiO$_3$ is added to the group of oxides with a 2DEG at their surface. Our
+study widens the phase space to investigate strontium and barium doped
+CaTiO$_3$ and the interplay of ferroelectric properties with the 2DEG at oxide
+surfaces. This could open up new paths to tailor two-dimensional transport
+properties of these systems towards possible applications.",1705.09495v1
+2017-05-30,"Two-dimensional electron systems in ATiO3 perovskites (A = Ca, Ba, Sr): control of orbital hybridization and order","We report the existence of a two-dimensional electron system (2DES) at the
+(001) surface of CaTiO3. Using angle-resolved photoemission spectroscopy, we
+find a hybridization between the d_xz and d_yz orbitals, not observed in the
+2DESs at the surfaces of other ATiO3 perovskites, e.g. SrTiO3 or BaTiO3. Based
+on a comparison of the 2DES properties in these three materials, we show how
+the electronic structure of the 2DES (bandwidth, orbital order and electron
+density) is coupled to different typical lattice distortions in perovskites.
+The orbital hybridization in orthorhombic CaTiO3 results from the rotation of
+the oxygen octahedra, which can also occur at the interface of oxide
+heterostructures to compensate strain. More generally, the control of the
+orbital order in 2DES by choosing different A-site cations in perovskites
+offers a new gateway towards 2DESs in oxide heterostructures beyond SrTiO3.",1705.10755v1
+2017-09-05,3D Nanoporous Gold with Very Low Parting Limit Derived from Au-based Metallic Glass and Enhanced Methanol Electro-oxidation Catalytic Performance,"Nanoporous gold (NPG) with bi-continuous ligaments and pores structure has
+promising potential in functional applications, among which one prominent
+example is fuel cell electrocatalyst. However, current application of NPG is
+mostly limited to methanol electro-oxidation due to its weak catalytic
+performance. Here we report a simple chemical dealloying process, for
+generating peculiar three-dimensional (3D) free-standing NPG with high specific
+surface area associated with a novel porous cone shaped protrusion morphology.
+This NPG structure possesses the highest specific activity of catalytic
+performance reported NPG catalysts so far.",1709.01376v1
+2017-09-14,Towards Universal Non-Volatile Resistance Switching in Non-metallic Monolayer Atomic Sheets,"Here, we report the intriguing observation of stable non-volatile resistance
+switching (NVRS) in single-layer atomic sheets sandwiched between metal
+electrodes. NVRS is observed in the prototypical semiconducting (MX2, M=Mo, W;
+and X=S, Se) transitional metal dichalcogenides (TMDs), and insulating
+hexagonal boron nitride (h-BN), which alludes to the universality of this
+phenomenon in non-metallic 2D monolayers, and features forming-free switching.
+This observation of NVRS phenomenon, widely attributed to ionic diffusion,
+filament and interfacial redox in bulk oxides and electrolytes, inspires new
+studies on defects, ion transport and energetics at the sharp interfaces
+between atomically-thin sheets and conducting electrodes. From a contemporary
+perspective, switching is all the more unexpected in monolayers since leakage
+current is a fundamental limit in ultra-thin oxides. Emerging device concepts
+in non-volatile flexible memory fabrics, and brain-inspired (neuromorphic)
+computing could benefit substantially from the pervasive NVRS effect and the
+associated wide materials and engineering co-design opportunity.
+Experimentally, a 50 GHz radio-frequency (RF) monolayer switch is demonstrated,
+which opens up a new application for electronic zero-static power RF switching
+technology.",1709.04592v1
+2017-09-21,Controlled manipulation of oxygen vacancies using nanoscale flexoelectricity,"Oxygen vacancies, especially their distribution, are directly coupled to the
+electromagnetic properties of oxides and related emergent functionalities that
+have implication in device applications. Here using a homoepitaxial strontium
+titanate thin film, we demonstrate a controlled manipulation of the oxygen
+vacancy distribution using the mechanical force from a scanning probe
+microscope tip. By combining Kelvin probe force microscopy imaging and
+phase-field simulations, we show that oxygen vacancies can move under a
+stress-gradient-induced depolarisation field. When tailored, this nanoscale
+flexoelectric effect enables a controlled spatial modulation. In motion, the
+scanning probe tip thereby deterministically reconfigures the spatial
+distribution of vacancies. The ability to locally manipulate oxygen vacancies
+on-demand provides a tool for the exploration of mesoscale quantum phenomena,
+and engineering multifunctional oxide devices.",1709.07201v1
+2017-09-26,Nanoscale Bandgap Tuning across an Inhomogeneous Ferroelectric Interface,"We report nanoscale bandgap engineering via a local strain across the
+inhomogeneous ferroelectric interface, which is controlled by the
+visible-light-excited probe voltage. Switchable photovolatic effects and the
+spectral response of the photocurrent were explore to illustrate the reversible
+bandgap variation (~0.3eV). This local-strain-engineered bandgap has been
+further revealed by in situ probe-voltage-assisted valence electron energy-loss
+spectroscopy (EELS). Phase-field simulations and first-principle calculations
+were also employed for illustration of the large local strain and the bandgap
+variation in ferroelectric perovskite oxides. This reversible bandgap tuning in
+complex oxides demonstrates a framework for the understanding of the
+opticallyrelated behaviors (photovoltaic, photoemission, and photocatalyst
+effects) affected by order parameters such as charge, orbital, and lattice
+parameters.",1709.08788v1
+2017-09-26,First-Principles Many-Body Investigation of Correlated Oxide Heterostructures: Few-Layer-Doped SmTiO$_3$,"Correlated oxide heterostructures pose a challenging problem in condensed
+matter research due to their structural complexity interweaved with demanding
+electron states beyond the effective single-particle picture. By exploring the
+correlated electronic structure of SmTiO$_3$ doped with few layers of SrO, we
+provide an insight into the complexity of such systems. Furthermore, it is
+shown how the advanced combination of band theory on the level of Kohn-Sham
+density functional theory with explicit many-body theory on the level of
+dynamical mean-field theory provides an adequate tool to cope with the problem.
+Coexistence of band-insulating, metallic and Mott-critical electronic regions
+is revealed in individual heterostructures with multi-orbital manifolds.
+Intriguing orbital polarizations, that qualitatively vary between the metallic
+and the Mott layers are also encountered.",1709.08875v1
+2017-11-03,Towards Hardware Implementation of Double-Layer Perceptron Based on Metal-Oxide Memristive Nanostructures,"Construction and training principles have been proposed and tested for an
+artificial neural network based on metal-oxide thin-film nanostructures
+possessing bipolar resistive switching (memristive) effect. Experimental
+electronic circuit of neural network is implemented as a double-layer
+perceptron with a weight matrix composed of 32 memristive devices. The network
+training algorithm takes into account technological variations of the
+parameters of memristive nanostructures. Despite the limited size of weight
+matrix the developed neural network model is well scalable and capable of
+solving nonlinear classification problems.",1711.01041v1
+2017-11-09,Room Temperature Giant Charge-to-Spin Conversion at SrTiO3/LaAlO3 Oxide Interface,"Two-dimensional electron gas (2DEG) formed at the interface between SrTiO3
+(STO) and LaAlO3 (LAO) insulating layer is supposed to possess strong Rashba
+spin-orbit coupling. To date, the inverse Edelstein effect (i.e. spin-to-charge
+conversion) in the 2DEG layer is reported. However, the direct effect of
+charge-to-spin conversion, an essential ingredient for spintronic devices in a
+current induced spin-orbit torque scheme, has not been demonstrated yet. Here
+we show, for the first time, a highly efficient spin generation with the
+efficiency of ~6.3 in the STO/LAO/CoFeB structure at room temperature by using
+spin torque ferromagnetic resonance. In addition, we suggest that the spin
+transmission through the LAO layer at high temperature range is attributed to
+the inelastic tunneling via localized states in the LAO band gap. Our findings
+may lead to potential applications in the oxide insulator based spintronic
+devices.",1711.03268v1
+2017-11-17,Atom Probe Analysis of Ex Situ Gas-Charged Stable Hydrides,"In this work, we report on the atom probe tomography analysis of two metallic
+hydrides formed by pressurized charging using an ex situ hydrogen charging
+cell, in the pressure range of 200-500 kPa (2-5 bar). Specifically we report on
+the deuterium charging of Pd/Rh and V systems. Using this ex situ system, we
+demonstrate the successful loading and subsequent atom probe analysis of
+deuterium within a Pd/Rh alloy, and demonstrate that deuterium is likely
+present within the oxide-metal interface of a native oxide formed on vanadium.
+Through these experiments, we demonstrate the feasibility of ex situ hydrogen
+analysis for hydrides via atom probe tomography, and thus a practical route to
+three-dimensional imaging of hydrogen in hydrides at the atomic scale.",1711.06667v1
+2017-11-20,Unconventional aspects of electronic transport in delafossite oxides,"The electronic transport properties of the delafossite oxides ABO$_2$ are
+usually understood in terms of two well separated entities, namely, the
+triangular A$^+$ and (BO$_2$)$^-$ layers. Here we review several cases among
+this extensive family of materials where the transport depends on the
+interlayer coupling and displays unconventional properties. We review the doped
+thermoelectrics based on CuRhO$_2$ and CuCrO$_2$, which show a high-temperature
+recovery of Fermi-liquid transport exponents, as well as the highly anisotropic
+metals PdCoO$_2$, PtCoO$_2$ and PdCrO$_2$ where the sheer simplicity of the
+Fermi surface leads to unconventional transport. We present some of the
+theoretical tools that have been used to investigate these transport properties
+and review what can and cannot be learned from the extensive set of electronic
+structure calculations that have been performed.",1711.07202v1
+2017-11-20,CFD investigation of thermal performance of aluminum oxide nanofluid in channel,"This paper shows the CFD investigation of pressure drop and thermal
+performance of aluminum oxide nano fluid inside square channel inserted a
+cylinder with and without fin using two-phase method. The constant heat flux on
+outer wall and laminar flow regime are applied in the considered domain using
+finite volume method. The results depict that the enhance of nano-particles
+volume concentration and Reynolds number have dramatic effects on heat transfer
+coefficient enhancement. Moreover, the increase of nano-particle diameter has
+opposite impact on heat transfer efficiency. The passive way leads to higher
+pressure drops. For all fluids under consideration, pressure drop escalated
+with Reynolds number. Injecting nano-particles into the water causes to
+increase in pressure drop and this impact is more significant in high
+nano-particle volume fraction.",1711.07407v2
+2017-11-28,Dendritic Growth of a Polymer on a 2D Mesoscale Square Lattice,"Dendritic growth patterns exhibiting four-fold anisotropy are observed when
+polyethylene oxide undergoes phase segregation from a solution phase to a solid
+phase. When this phase transition occurs on a substrate that has patterns of
+cross-linked polyethylene oxide resist pillars made using electron beam
+lithography, the polymer grows in between the patterns giving rise to dendritic
+growth structures exhibiting eight-fold anisotropy. This paper presents these
+experimental observations and explains the dendritic growth using principles of
+minimization of free energy associated with phase change. Numerical simulations
+are carried out using phase-field modeling, and the results are shown to
+qualitatively match experimental observations. The simulations reveal that the
+polymer assumes the anisotropy of the patterned lattice.",1711.10141v3
+2018-03-06,Atomic Visualization of Copper Oxide Structure in Infinite-Layer Cuprate SrCuO2,"We report on atomic-scale visualization of the structure of infinite-layer
+cuprate SrCuO2 thin films grown on Nb-doped SrTiO3 substrates by molecular beam
+epitaxy. In-situ scanning tunneling microscopy study reveals stoichiometric
+copper oxide (CuO2) plane with a 2 x 2 surface reconstruction, prompted by
+preferential clustering of four adjacent CuO2 plaquettes. By imaging the
+subsurface Sr atoms, intra-unit-cell rotational symmetry breaking is observed,
+which, together with the adjacent CuO2 clustering, can be well accounted for by
+a periodic up-down buckling of oxygen ions on the CuO2 plane. Further
+post-annealing leads to an incommensurate stripe structure of the surface
+layer. Our findings provide important structural information for deeply
+understanding the electronic structure of superconducting CuO2 plane as well as
+high temperature superconductivity in cuprates.",1803.02033v2
+2018-03-08,Design of a nickel-base superalloy using a neural network,"A new computational tool has been developed to model, discover, and optimize
+new alloys that simultaneously satisfy up to eleven physical criteria. An
+artificial neural network is trained from pre-existing materials data that
+enables the prediction of individual material properties both as a function of
+composition and heat treatment routine, which allows it to optimize the
+material properties to search for the material with properties most likely to
+exceed a target criteria. We design a new polycrystalline nickel-base
+superalloy with the optimal combination of cost, density, gamma' phase content
+and solvus, phase stability, fatigue life, yield stress, ultimate tensile
+strength, stress rupture, oxidation resistance, and tensile elongation.
+Experimental data demonstrates that the proposed alloy fulfills the
+computational predictions, possessing multiple physical properties,
+particularly oxidation resistance and yield stress, that exceed existing
+commercially available alloys.",1803.03039v1
+2018-03-10,Continuum Charge Excitations in High-Valence Transition-Metal Oxides Revealed by Resonant Inelastic X-ray Scattering,"We present a theoretical investigation of the origin of Raman-like and
+fluorescencelike (FL) features of resonant inelastic x-ray scattering (RIXS)
+spectra. Using a combination of local-density approximation + dynamical
+mean-field theory and a configuration interaction solver for Anderson impurity
+model, we calculate the $L$-edge RIXS and x-ray absorption spectra of
+high-valence transition-metal oxides LaCuO$_3$ and NaCuO$_2$. We analyze in
+detail the behavior of the FL feature and show how it is connected to the
+details of electronic and crystal structure. On the studied compounds we
+demonstrate how material details determine whether the electron-hole continuum
+can be excited in the $L$-edge RIXS process.",1803.03820v4
+2018-03-16,Evolution of superconductivity in ultrathin NbS2,"We report a systematic study of thickness-dependent superconductivity and
+carrier transport properties in exfoliated layered 2H-NbS2. Hall-effect
+measurements reveal 2H-NbS2 in its normal state to be a p-type metal with hole
+mobility of 1-3 cm2/Vs. The superconducting transition temperature is found to
+decrease with thickness. We find that the suppression of superconductivity is
+due to disorder resulting from the incorporation of atmospheric oxygen and a
+reduced hole density. Cross-section transmission electron microscope (TEM)
+imaging reveals a chemical change of NbS2 in ambient conditions, resulting in
+the formation of amorphous oxide layers sandwiching crystalline layered NbS2.
+Though few-nm-thick 2H-NbS2 completely converts to amorphous oxide in ambient
+conditions, PMMA encapsulation prevents further chemical change and preserves
+superconductivity.",1803.06097v1
+2018-02-19,Synthesis and Characterization of Copper Doped Zinc Oxide Thin Films for CO Gas Sensing,"Objective of this work was to synthesize Copper doped Zinc Oxide (CZO) films
+and optimization of process parameters by varying molarity of zinc acetate
+dehydrate from 0.5 M to 1.0 M, concentration of copper acetate monohydrate from
+1% to 5 % and annealing temperature from 200 C to 300 C to measure the
+sensitivity of CZO films for CO (Carbon Monoxide) gas. The concentration of CO
+gas was maintained at 5 ppm and operating temperature of 250 oC was used for
+sensing. Analysis for sensitivity showed highest grading for parametric
+combination of 0.75 molarity, 3% copper concentration and 300 C annealing
+temperature with surface roughness of 3.90 nm and grain size of 256 nm. TEM
+image revealed the crystalline grain size was 5 nm. ANOVA showed that annealing
+temperature influenced the sensitivity by 69.06 % .",1803.07144v1
+2018-03-12,ALLEGRO Core Degradation Study using MELCOR 2.1,"ALLEGRO is an experimental high-temperature gas (He)-cooled fast reactor
+(GFR) under development by the European Consortium V4G4 Centre of Excellence on
+basis of the concept ALLEGRO presented by CEA in 2009. Its main purpose is to
+demonstrate the viability of GFR in pilot scale and simultaneously serve as a
+test bed for GFR-related technologies, above all the high-temperature resistant
+refractory fuel in the conventional oxide fuel driver core. Severe accident
+studies of the concept with the first core (oxide fuel in stainless steel
+claddings) are an important part of safety analyses leading to improves in
+reactor design and safety. This paper extends our previous study using the
+MELCOR code. Major difference between the previous and this work is decrease of
+thermal power and power density to 50 MWth and 66,6 MWth/m3 respectively.
+Analyses are focused on protected scenarios based on total station blackout
+individually aggravated by loss of primary coolant, water ingress into primary
+coolant or malfunction of check valves in the decay heat removal system. The
+results indicate the timing and extent of core degradation and provide valuable
+data for design of the core catcher in ALLEGRO.",1803.07652v1
+2018-03-28,Porous silicon carbide and aluminum oxide with unidirectional open porosity as model target materials for radioisotope beam production,"New silicon carbide (SiC) and aluminum oxide (Al2O3) of a tailor-made
+microstructure were produced using the ice-templating technique, which permits
+controlled pore formation conditions within the material. These prototypes will
+serve to verify aging of the new advanced target materials under irradiation
+with proton beams. Before this, the evaluation of their mechanical integrity
+was made based on the energy deposition spectra produced by FLUKA codes.",1803.10527v1
+2018-06-01,Hot-electron mediated ion diffusion in proton-irradiated magnesium oxide,"Highly energetic ions that impact materials have applications from
+semiconductor industry to medicine, and are fundamentally interesting as they
+trigger multi-length and time-scale processes. In particular, they excite
+electrons into non-thermalized energy distributions with subsequent
+non-equilibrium electron-electron and electron-ion dynamics. In order to
+achieve a quantitative description of these, we propose a general
+first-principles framework that bridges time scales from ultrafast electron
+dynamics directly after impact, to ion diffusion over migration barriers in
+semiconductors. We apply it to magnesium oxide under proton irradiation and
+discover a diffusion mechanism that is mediated by hot electrons. Our
+quantitative simulations show that this mechanism strongly depends on the
+projectile-ion velocity. This indicates that it may occur only at a specific
+penetration depth in the target and that it can be triggered by varying the
+kinetic energy of the particle radiation. Either of these predictions should
+facilitate direct experimental observation of this effect and significantly
+advances current understanding of non-equilibrium electron-ion dynamics.",1806.00443v3
+2018-06-05,Reaction front occurrence on imperfection profiles during oxygen chemical diffusion in oxides. I. Thermodynamic background,"We present a theoretical study of the impact of oxygen diffusion in oxide
+crystals on metal dopants ionic state and the conduction type under thermal
+equilibrium. Oxygen vacancy formation acting as a shallow, double-electronic
+donor is assumed to result from the crystal exposure to a low ambient oxygen
+pressure. It is shown, that critical transitions from n- to a p-type at an
+oxygen partial pressure Pi, and in ionization state of the metal dopant at an
+oxygen partial pressure PM, are usually not simultaneous, and depend on the
+different reaction constants. Experimental study of the different species
+concentrations at thermodynamic equilibrium as functions of pressure and
+temperature should allow assessment of various reversible reaction constants
+controlling the process. In the Part II companion paper, the kinetic
+(diffusion) characteristics are considered in detail.",1806.01687v1
+2018-06-05,Reaction front occurrence on imperfection profiles during oxygen chemical diffusion in oxides. II. Kinetic analysis,"We present a theoretical study of the impact of oxygen diffusion in oxide
+crystals on metal dopants ionic state and the conduction type under dynamic
+changes. The slow changes under thermal equilibrium are provided in a
+companion, Part I paper. Oxygen vacancy formation acting as a shallow,
+double-electronic donor, is assumed to result from the crystal exposure to a
+low ambient oxygen pressure. Critical transitions from n- to a p-type at an
+oxygen partial pressure Pi, and in ionization state of the metal dopant at an
+oxygen partial pressure PM, are usually not simultaneous, and depend on the
+different reaction constants. Invoking ambipolar diffusion for all
+participating species, it is shown that oxygen vacancy diffusion exhibits well
+defined characteristics in specific regions of the vacancy concentration
+related to the said critical pressures. Particularly, the oxygen chemical
+diffusivity is practically constant between Pi and PM, and increases sharply
+for pressures P << Pi,PM and P >> P,PM. Prominent reaction fronts occur under
+specific conditions in the two latter regions.",1806.01706v1
+2018-06-06,Single-band to two-band superconductivity transition in two-dimensional oxide interfaces,"In multiorbital materials, superconductivity can exhibit new exotic forms
+that include several coupled condensates. In this context, quantum confinement
+in two-dimensional superconducting oxide interfaces offers new degrees of
+freedom to engineer the band structure and selectively control 3d-orbitals
+occupancy by electrostatic doping. However, the presence of multiple
+superconducting condensates in these systems has not yet been demonstrated.
+Here, we use resonant microwave transport to extract the superfluid stiffness
+of the (110)-oriented LaAlO3/SrTiO3 interface in the entire phase diagram. We
+evidence a transition from single-band to two-band superconductivity driven by
+electrostatic doping, which we relate to the filling of the different
+3d-orbitals based on numerical simulations of the quantum well. Interestingly,
+the superconducting transition temperature decreases while the second band is
+populated, which challenges the Bardeen-Cooper-Schrieffer theory. To explain
+this behaviour, we propose that the superconducting order parameters associated
+with the two bands have opposite signs with respect to each other.",1806.02212v1
+2018-06-11,Evaluation of Porosity for Gamma Irradiated Poly(ethylene oxide): A New Approach Using Microscopic Image Aided with Computer Programming,"Porous polymer films of Poly(ethylene oxide)(PEO) are synthesized by solution
+casting technique using gamma irradiated: (a) PEO powder (S-series) and (b) PEO
+- methanol solution (L-series). Pore phase forms instantaneously during
+preparation. Optimization of the pore content and distribution enables
+tailoring of associated properties for multifaceted applications. This method
+could be analyzed for mapping of porosity and average pore size. Practicability
+and repeatability of the developed programme has been established for
+monophasic system using backscattered imaging mode of SEM. This program is
+underdevelopment, but PROGIMAGE-POR bears the novelty of using image from
+either 2D-or 3D imaging system and could be applied for intricate
+composite/layered system.",1806.03777v1
+2018-06-11,Inverted structure perovskite solar cells: A theoretical study,"We analysed perovskite CH3NH3PbI3-xClx inverted planner structure solar cell
+with nickel oxide (NiO) and spiro-MeOTAD as hole conductors. This structure is
+free from electron transport layer. The thickness is optimized for NiO and
+spiro-MeOTAD hole conducting materials and the devices do not exhibit any
+significant variation for both hole transport materials. The back metal contact
+work function is varied for NiO hole conductor and observed that Ni and Co
+metals may be suitable back contacts for efficient carrier dynamics. The solar
+photovoltaic performance showed a linear decrease in efficiency with increasing
+temperature. The electron affinity and band gap of transparent conducting oxide
+and NiO layers are varied to understand their impact on conduction and valence
+band offsets. A range of suitable band gap and electron affinity values are
+found essential for efficient device performance.",1806.03950v1
+2018-06-28,Optoelectronic properties of zinc oxide: A first-principles investigation using the Tran-Blaha modified Becke-Johnson potentia,"In this work we use density functional theory (DFT) to investigate the
+influence of semi-local exchange and correlation effects on the electronic and
+optical properties of zinc oxide. We find that the inclusion of such effects
+using the Tran-Blaha modified Becke-Johnson potential yields an excellent
+description of the electronic structure of this material giving energy band gap
+which is systematically larger than the one obtained with standard local
+functionals such as the generalized gradient approximation. The discrepancy
+between the experimental and theoretical band gaps is then significantly
+reduced at a computational low cost. We also calculated the dielectric
+functions of ZnO and find a violet shift to the absorption edge which is in
+good agreement with experimental results.",1806.11016v1
+2018-06-28,Single Crystal High Entropy Perovskite Oxide Epitaxial Films,"The first examples of single crystal epitaxial thin films of a high entropy
+perovskite oxide are synthesized. Pulsed laser deposition is used to grow the
+configurationally disordered ABO3 perovskite, Ba(Zr0.2Sn0.2Ti0.2Hf0.2Nb0.2)O3,
+epitaxially on SrTiO3 and MgO substrates. X-ray diffraction and scanning
+transmission electron microscopy demonstrate that the films are single phase
+with excellent crystallinity and atomically abrupt interfaces to the underlying
+substrates. Atomically-resolved electron energy loss spectroscopy mapping shows
+a uniform and random distribution of all B-site cations. The ability to
+stabilize perovskites with this level of configurational disorder offers new
+possibilities for designing materials from a much broader combinatorial cation
+pallet while providing a fresh avenue for fundamental studies in strongly
+correlated quantum materials where local disorder can play a critical role in
+determining macroscopic properties.",1806.11209v1
+2018-06-30,Stability of charges in titanium compounds and charge transfer to oxygen in titanium dioxide,"We investigate the charge density distribution in titanium dioxide, molecular
+titanium complexes and a variety of periodic titanium compounds using
+delocalization indices and Bader charge analysis. Our results are in agreement
+with previous experimental and theoretical investigations on the charge
+stability and deviation from formal oxidation states in transition metal
+compounds. We present examples for practically relevant redox processes, using
+molecular titanium dioxide model systems, that illustrate the failure of formal
+oxidation states to account for some redox phenomena. We observe a pronounced
+charge stability on titanium for trial systems which are expected to be mainly
+ionic. No environment tested by us is capable to reduce the local titanium
+charge remainder below one electron.",1807.00115v1
+2018-06-30,"Theoretical specific heat, and thermal conductivity estimated by detailed phonon vibrations","We report the calculation results of specific heat ($c_v$), and thermal
+conductivity ($\kappa$) by using Einstein, and Debye models about rock salt
+(NaCl), oxides: Na$_x$CoO$_2$, SrTiO$_3$, and LiNbO$_3$. In calculation, the
+longitudinal (L), and transverse (T) sound velocities ($v_T$, $v_L$) were
+estimated from acoustic phonons' dispersion's (~$\omega$/$K$) in above
+materials, and the average sound velocities ($v_a$) were input into Debye model
+for $\kappa$ equation, and results were compared with that of Einstein model.
+In some oxides, $v_a$ is relatively reduced at slight high $v_T$
+($v_T$/$v_L$=0.3-0.5). The relation of $\kappa$, $v_a$ and $T$ were imaged as
+the contour plots about realizing low $\kappa$ values to be application of
+thermoelectric properties.",1807.00237v2
+2018-07-03,Tuning oxygen vacancy diffusion through strain in SrTiO$_3$ thin films,"Understanding the diffusion of oxygen vacancies in oxides under different
+external stimuli is crucial for the design of ion-based electronic devices,
+improve catalytic performance, etc. In this manuscript, using an external
+electric field produced by an AFM tip, we obtain the room-temperature diffusion
+coefficient of oxygen-vacancies in thin-films of SrTiO$_3$ under
+compressive/tensile epitaxial strain. Tensile strain produces a substantial
+increase of the diffusion coefficient, facilitating the mobility of vacancies
+through the film. Additionally, the effect of tip bias, pulse time, and
+temperature on the local concentration of vacancies is investigated. These are
+important parameters of control in the production and stabilization of
+non-volatile states in ion-based memresistive devices. Our findings show the
+key role played by strain for the control of oxygen vacancy migration in
+thin-film oxides.",1807.01008v1
+2018-07-12,Superior thermal conductivity of poly (ethylene oxide) for solid-state electrolytes: a molecular dynamics study,"Solid-state lithium-ion batteries (SSLIBs) are considered to be the new
+generation of devices for energy storage due to better performance and safety.
+Poly (ethylene oxide) (PEO) based material becomes one of the best candidate of
+solid electrolytes, while its thermal conductivity is crucial to heat
+dissipation inside batteries. In this work, we study the thermal conductivity
+of PEO by molecular dynamics simulation. By enhancing the structure order,
+thermal conductivity of aligned crystalline PEO is obtained as high as 60 W/m-K
+at room temperature, which is two orders higher than the value (0.37 W/m-K) of
+amorphous structure. Interestingly, thermal conductivity of ordered structure
+shows a significant stepwise negative temperature dependence, which is
+attributed to the temperature-induced morphology change. Our study offers
+useful insights into the fundamental mechanisms that govern the thermal
+conductivity of PEO but not hinder the ionic transport, which can be used for
+the thermal management and further optimization of high-performance SSLIBs.",1807.04412v2
+2018-07-19,Detailed analysis of transitions in the CO oxidation on Palladium(111) under noisy conditions,"It has been shown that CO oxidation on Pd(111) under ultra-high vacuum
+conditions can suffer rare transitions between two stable states triggered by
+weak intrinsic perturbations. Here we study the effects of adding controlled
+noise by varying the concentrations of O2 and CO that feed the vacuum chamber,
+while the total flux stays constant. In addition to the regime of rare
+transitions between states of different CO2 reaction rate induced by intrinsic
+fluctuations, we found three distinct effects of external noise depending on
+its strength: small noise suppresses transitions and stabilizes the upper rate
+state; medium noise induces bursting; and large noise gives rise to reversible
+transitions in both directions. To explain some of the features present in the
+dynamics, we propose an extended stochastic model that includes a global
+coupling through the gas phase to account for the removal of CO gas caused by
+the adsorption of the Pd surface. The numerical simulations based in the model
+show a qualitative agreement with the noise-induced transitions found in
+experiments, but suggest that more complex spatial phenomena are present in the
+observed fluctuations.",1807.07219v1
+2018-07-19,The Effect of Hole Transporting Layer in Charge Accumulation Properties of p-i-n Perovskite Solar Cells,"The charge accumulation properties of p-i-n perovskite solar cells were
+investigated using three representative organic and inorganic hole transporting
+layer (HTLs): a) Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate)
+(PEDOT:PSS, Al 4083), b) copper-doped nickel oxide (Cu:NiOx) and c) Copper
+oxide (CuO). Through impedance spectroscopy analysis and modelling it is shown
+that charge accumulation is decreased in the HTL/Perovskite interface, between
+PEDOT:PSS to Cu:NiOx and CuO respectively. This was indicative from the
+decrease in double layer capacitance (Cdl) and interfacial charge accumulation
+capacitance (Cel), resulting in an increase to recombination resistance (Rrec),
+thus decreased charge recombination events between the three HTLs. Through AFM
+measurements it is also shown that the reduced recombination events (followed
+by the increase in Rrec) is also a result of increased grain size between the
+three HTLs, thus reduction in the grain boundaries area. These charge
+accumulation properties of the three HTLs have resulted in an increase to the
+power conversion efficiency between the PEDOT:PSS (8.44%), Cu:NiOx (11.45%) and
+CuO (15.3%)-based devices.",1807.07308v1
+2018-07-19,Dielectric Properties and Ion Transport in Layered MoS_{2} Grown by Vapor-Phase Sulfurization,"Electronic and dielectric properties of vapor-phase grown MoS_{2} have been
+investigated in metal/MoS_{2}/silicon capacitor structures by
+capacitance-voltage and conductancevoltage techniques. Analytical methods
+confirm the MoS_{2} layered structure, the presence of interfacial silicon
+oxide (SiO_{x}) and the composition of the films. Electrical characteristics in
+combination with theoretical considerations quantify the concentration of
+electron states at the interface between Si and a 2.5 - 3 nm thick silicon
+oxide interlayer between Si and MoS_{2}. Measurements under electric field
+stress indicate the existence of mobile ions in MoS_{2} that interact with
+interface states. Based on time-offlight secondary ion mass spectrometry, we
+propose OH^{-} ions as probable candidates responsible for the observations.
+The dielectric constant of the vapor-phase grown MoS_{2} extracted from CV
+measurements at 100 KHz is in the range of 2.6 to 2.9. The present study
+advances the understanding of defects and interface states in MoS_{2}. It also
+indicates opportunities for ion-based plasticity in 2D material devices for
+neuromorphic computing applications.",1807.07592v1
+2018-07-23,The role of metastability in enhancing water-oxidation activity,"While metastability enhanced water-oxidation activity was experimentally
+reported, the reason behind this effect is still unclear. We determine here,
+using density functional theory calculations, oxygen evolution reaction
+overpotentials for a variety of defective (001) surfaces of three different
+perovskite materials. For all three, we find a large range of overpotentials
+for different reaction sites including also overpotentials at the top of the
+activity volcano. Assuming that these sites dominate the apparent catalytic
+activity, this implies that a large number of geometrically different reaction
+sites, as they occur when a catalyst is operated at the border of its stability
+conditions, can lead to a strong enhancement of the apparent activity. This
+also implies that a pre-treatment of the catalyst creating a variety of
+different reactive sites could lead to superior catalytic activities for
+thermodynamically stable materials.",1807.08546v4
+2018-07-29,Lifting of Spin Blockade by Charged Impurities in Si-MOS Double Quantum Dot Devices,"One obstacle that has slowed the development of electrically gated
+metal-oxide-semiconductor (MOS) singlet-triplet qubits is the frequent lack of
+observed spin blockade, even in samples with large singlet-triplet energy
+splittings. We present theoretical and experimental evidence that the cause of
+this problem in MOS double quantum dots is the stray positive charges in the
+oxide inducing accidental levels near the device's active region that allow
+spin blockade lifting. We also present evidence that these effects can be
+mitigated by device design modifications, such as overlapping gates.",1807.11064v3
+2018-08-01,Low-loss integrated photonics for the blue and ultraviolet regime,"We present a low-loss integrated photonics platform in the visible and near
+ultraviolet regime. Fully-etched waveguides based on atomic layer deposition
+(ALD) of aluminum oxide operate in a single transverse mode with $<$3 dB/cm
+propagation loss at a wavelength of 371 nm. Ring resonators with intrinsic
+quality factors exceeding 470,000 are demonstrated at 405 nm, and the thermo
+optic coefficient of ALD aluminum oxide is estimated to be $2.75\times10^{-5}$
+[RIU/$^\circ$C]. Absorption loss is sufficiently low to allow on-resonance
+operation with intra-cavity powers up to at least 12.5 mW, limited by available
+laser power. Experimental and simulated data indicates the propagation loss is
+dominated by sidewall roughness, suggesting lower loss in the blue and UV is
+achievable.",1808.00429v2
+2018-08-06,Stress-sign-tunable Poisson's Ratio in Monolayer Blue Phosphorus Oxide,"Negative Poisson's ratio (NPR) materials have attracted tremendous interest
+due to their unusual physical properties and potential applications. Certain
+two-dimensional (2D) monolayer materials have also been found to exhibit NPR
+and the corresponding deformation mechanism varies. In this study, we found,
+based on first-principles calculations, that the Poisson's ratio (PR) sign of
+monolayer Blue Phosphorus Oxide (BPO) can be tuned by strain: the PR is
+positive under uniaxial strain <= -1% but becomes negative under > 0. The
+deformation mechanism for BPO under strain depends on the mutual competition
+between the P-P attraction and P-O repulsion effect, and these two factors
+induce two different deformation pathways (one with positive PR, and the other
+with NPR). Moreover, with increasing of strain, both the decreased strength of
+P-P attraction and the increased strength of P-O repulsion effect modulate the
+PR of BPO from positive to negative.",1808.01733v2
+2018-08-08,An operando calorimeter for high temperature electrochemical cells,"Operando calorimetry has previously been utilized to study degradation, side
+reactions, and other electrochemical effects in electrochemical cells such as
+batteries at or near room temperature. Calorimetric data can provide important
+information on the lifetime and thermal properties of electrochemical cells and
+can be used in practical engineering applications such as thermal management.
+High temperature electrochemical cells such as solid oxide fuel cells or
+electrolyzers can also benefit from operando calorimetry, although to our
+knowledge no such unit has been developed commercially. Herein, we report an
+operando calorimeter capable of simultaneous calorimetry and electrochemistry
+at temperatures up to 1,000 {\deg}C and in both oxidizing and reducing
+atmospheres. The calorimeter is constructed by modifying a commercial apparatus
+originally designed to study high temperature electrochemical cells in various
+gas environments. We utilize a grey-box, nonlinear system identification model
+to analyze calorimetric data and achieve an electrochemical cell power
+sensitivity of 16.1 +/- 11.7 mW. This operando calorimeter provides the tools
+needed to study both the thermal and kinetic behavior of electrochemical cells
+at elevated temperatures.",1808.02596v1
+2018-08-11,Polaritonic hybrid-epsilon-near-zero modes: engineering strong optoelectronic coupling and dispersion in doped cadmium oxide bilayers,"Polaritonic materials that support epsilon-near-zero (ENZ) modes offer the
+opportunity to design light-matter interactions at the nanoscale through
+phenomena like resonant perfect absorption and extreme sub-wavelength light
+concentration. To date, the utility of ENZ modes is limited in propagating
+polaritonic systems by a relatively flat spectral dispersion, which gives ENZ
+modes small group velocities and short propagation lengths. Here we overcome
+this constraint by coupling ENZ modes to surface plasmon polariton (SPP) modes
+in doped cadmium oxide ENZ-on-SPP bilayers. What results is a strongly coupled
+hybrid mode, characterized by strong anti-crossing and a large spectral
+splitting on the order of 1/3 of the mode frequency. The resonant frequencies,
+dispersion, and coupling of these polaritonic-hybrid-epsilon-near-zero (PH-ENZ)
+modes are controlled by tailoring the modal oscillator strength and the ENZ-SPP
+spectral overlap, which can potentially be utilized for actively tunable strong
+coupling at the nanoscale. PH-ENZ modes ultimately leverage the most desirable
+characteristics of both ENZ and SPP modes through simultaneous strong interior
+field confinement and mode propagation.",1808.03847v1
+2018-08-21,Cu:ZnO deposited on porous ceramic substrates by a simple thermal method for photocatalytic application,"Thin films of undoped zinc oxide (ZnO) and doped ZnO with copper were
+deposited on ceramic pellets made from abundant local clay materials with an
+addition of zirconia (ZrO2). The thin layers were prepared by a thermal method
+using an autoclave. The resulting structural and morphological properties of
+the products were studied in order to determine the effectiveness of their
+photocatalytic activities. X-ray diffraction, Scanning Electron Microscopy,
+energy-dispersive X-ray spectroscopy and UV-visible spectrophotometry were used
+in this goal. An application test was carried out to quantify the
+photocatalytic degradation of a toxic organic dye by these samples under UV
+light. In similar conditions, the layers deposited on the ceramics with
+addition of zirconia have shown better performances than those without
+zirconia. This result can be related to the porosity created when the zirconium
+oxide reacted with SiO2 of the clay. The open porosity observed on this type of
+substrate allows a larger surface for the photocatalysis. The degradation rate
+of the dye reached 90.5 % during a period of 7 hours with Cu doped ZnO thin
+layers deposited on porous substrates modified with addition of ZrO2.",1808.06786v1
+2018-08-23,Model Building of Metal Oxide Surfaces and Vibronic Coupling Density as a Reactivity Index: Regioselectivity of CO$_2$ Adsorption on Ag-loaded Ga$_2$O$_3$,"The step-by-step hydrogen-terminated (SSHT) model is proposed as a model for
+the surfaces of metal oxides. Using this model, it is found that the vibronic
+coupling density (VCD) can be employed as a reactivity index for surface
+reactions. As an example, the regioselectivity of CO$_2$ adsorption on the
+Ag-loaded Ga$_2$O$_3$ photocatalyst surface is investigated based on VCD
+analysis. The cluster model constructed by the SSHT approach reasonably
+reflects the electronic structures of the Ga$_2$O$_3$ surface. The geometry of
+CO$_2$ adsorbed on the Ag-loaded Ga$_2$O$_3$ cluster has a bent structure,
+which is favorable for its photocatalytic reduction to CO.",1808.07740v1
+2018-08-28,Theory of charge-spin conversion at oxide interfaces: The inverse spin-galvanic effect,"We evaluate the non-equilibrium spin polarization induced by an applied
+electric field for a tight-binding model of electron states at oxides
+interfaces in LAO/STO heterostructures. By a combination of analytic and
+numerical approaches we investigate how the spin texture of the electron
+eigenstates due to the interplay of spin-orbit coupling and inversion asymmetry
+determines the sign of the induced spin polarization as a function of the
+chemical potential or band filling, both in the absence and presence of local
+disorder. With the latter, we find that the induced spin polarization evolves
+from a non monotonous behavior at zero temperature to a monotonous one at
+higher temperature. Our results may provide a sound framework for the
+interpretation of recent experiments.",1808.09157v1
+2018-08-29,Synthesizing Cu-Sn nanowires alloy in highly-ordered Aluminum Oxide templates by using electrodeposition method,"In this research a novel and simple electrochemical method is developed in
+order to facilitate the large-scale production of nanowires. The proposed
+electrochemical technique shows versatile controllability over chemical
+composition and crystalline structure of Cu-Sn nanowires. Another important
+factor, which could be controlled by using this method, is the order structure
+of nanowires more accurately in comparison to conventional synthesizing
+procedures. As a result, the Cu-Sn nanowires as well as Aluminum Oxide
+templates synthesized by using the proposed electrochemical method are examined
+due to their morphology and chemical structure to find a relation between
+electrodeposition's solution chemistry and materials properties of Cu-Sn
+nanowires. The results show that the proposed electrochemical method maintains
+a highly-ordered morphology as well as versatile controllability over chemical
+composition of nanowires, which could be used to optimize the procedure for
+industrial applications due to low cost and simple experimental setup.",1808.09838v1
+2018-12-04,Absolute Reference Energy to Realign the Band-edges of Inorganic Semiconductors Using First-principles Calculations,"The challenge of finding an absolute reference energy from first-principles
+simulations to realigning semiconductor's valence band-top and conduction
+band-bottom, a theoretical methodology is proposed based on plane-wave
+calculations as implemented within state-of-art density functional theory. We
+have studied some of inorganic binary semiconductors, including both oxides and
+non-oxides, as for example rutile- and anatase TiO2, wurtzite ZnO, rutile SnO2,
+blende phase of GaP, GaAs, InP, ZnTe, CdS, CdSe, and SiC, those are well known
+and qualitatively important for photoelectrochemical, optoelectronic device
+applications in their standalone and/or heterostructure morphologies. The
+calculated band-edges of these well known semiconductors are realigned with
+respect to our proposed absolute vacuum reference energy, which is defined with
+our proposed corrections and compared to their available experimental values
+from flat-band measurement. The prediction is reasonably well agreed with known
+experimental flat-band measured data. Our estimated mean absolute error bar for
+these set of eleven compounds is ~ 0.17 eV, closer to the known experimental
+limit 0.10-0.20 eV.",1812.01293v2
+2018-12-07,An atomically thin oxide layer on the elemental superconductor Ta(001) surface,"Recently the oxygen-reconstructed tantalum surface Ta(001)-p(3$\times$3)-O
+has experienced considerable attention due its use as a potential platform for
+Majorana physics in adatom chains. Experimental studies using scanning
+tunneling microscopy and spectroscopy found rich atomic and electronic
+structures already for the clean Ta(001)-O surface, which we combine here with
+$ab~initio$ methods. We discover two metastable superstructures at the root of
+the different topographic patterns, discuss its emergence during annealing, and
+identify the electronic properties. The latter is determined as the sole origin
+for the contrast reversal seen at positive bias. The observed effects are
+essentially connected to the two distinct oxygen states appearing on the
+surface in different geometries. The second superstructure was found in
+simulations by introducing oxygen vacancies, what was also observed in tantalum
+pentoxide systems. Additionally we study the charge distribution on the
+oxidized surface and underline its importance for the adsorption process of
+polarizable atoms and molecules.",1812.03141v1
+2018-12-12,The use of strain to tailor electronic thermoelectric transport properties: A first principles study of 2H-phase CuAlO2,"Using first principles calculations, the use of strain to adjust electronic
+transport and the resultant thermoelectric (TE) properties is discussed using
+2H phase CuAlO2 as a test case. Transparent oxide materials, such as CuAlO2, a
+p-type transparent conducting oxide (TCO), have recently been studied for high
+temperature thermoelectric power generators and coolers for waste heat. Given
+TCO materials with relative ease of fabrication, low cost of materials, and
+non-toxicity, the ability to tailor them to specific temperature ranges, power
+needs, and size requirements, through the use of strain opens an interesting
+avenue. We find that strain can have a significant effect on these properties,
+in some cases detrimental and in others beneficial, including the potential for
+n-type power factors larger than the highest p-type case. The physical reasons
+for this behavior are explained in the terms of the thermoelectric transport
+distribution and the Landauer distribution of modes.",1812.05085v1
+2018-12-13,On the Ferroelectric Polarization Switching of Hafnium Zirconium Oxide in Ferroelectric/Dielectric Stack,"The ferroelectric polarization switching in ferroelectric hafnium zirconium
+oxide (Hf0.5Zr0.5O2, HZO) in the HZO/Al2O3 ferroelectric/dielectric stack is
+investigated systematically by capacitance-voltage and polarization-voltage
+measurements. The thickness of dielectric layer is found to have a determinant
+impact on the ferroelectric polarization switching of ferroelectric HZO. A
+suppression of ferroelectricity is observed with thick dielectric layer. In the
+gate stacks with thin dielectric layers, a full polarization switching of the
+ferroelectric layer is found possible by the proposed leakage-current-assist
+mechanism through the ultrathin dielectric layer. Theoretical simulation
+results agree well with experimental data. This work clarifies some of the
+critical parts of the long-standing confusions and debating related to negative
+capacitance field-effect transistors (NC-FETs) concepts and experiments.",1812.05260v2
+2018-12-28,Anti-doping in Insulators and Semiconductors having Intermediate Bands with Trapped Carriers,"Ordinary doping by electrons (holes) generally means that the Fermi level
+shifts towards the conduction band (valence band) and that the conductivity of
+free carriers increases. Recently, however, some peculiar doping
+characteristics were sporadically recorded in different materials without
+noting the mechanism: electron doping was observed to cause a portion of the
+lowest unoccupied band to merge into the valance band, leading to a decrease in
+conductivity. This behavior we dub as 'anti-doping' was seen in rare-earth
+nickel oxides SmNiO3, cobalt oxides SrCoO2.5, Li-ion battery materials and even
+MgO with metal vacancies. We describe the physical origin of anti-doping as
+well as its inverse problem, the 'design principles' that would enable
+intelligent search of materials. We find that electron anti-doping is expected
+in materials having pre-existing trapped holes and is caused by annihilation of
+such 'hole polarons' via electron doping. This may offer an unconventional way
+of controlling conductivity.",1812.10894v2
+2019-01-08,Enhanced Seebeck coefficient by a filling-induced Lifshitz transition in KxRhO2,"We have systematically measured the transport properties in the layered
+rhodium oxide K$_{x}$RhO$_{2}$ single crystals ($0.5\lesssim x \lesssim 0.67$),
+which is isostructural to the thermoelectric oxide Na$_{x}$CoO$_{2}$. We find
+that below $x = 0.64$ the Seebeck coefficient is anomalously enhanced at low
+temperatures with increasing $x$, while it is proportional to the temperature
+like a conventional metal above $x=0.65$, suggesting an existence of a critical
+content $x^{*} \simeq 0.65$. For the origin of this anomalous behavior, we
+discuss a filling-induced Lifshitz transition, which is characterized by a
+sudden topological change in the cylindrical hole Fermi surfaces at the
+critical content $x^*$.",1901.02116v1
+2019-01-15,Limitations of the DFT-1/2 method for covalent semiconductors and transition-metal oxides,"The DFT-1/2 method in density functional theory [L. G. Ferreira et al., Phys.
+Rev. B 78, 125116 (2008)] aims to provide accurate band gaps at the
+computational cost of semilocal calculations. The method has shown promise in a
+large number of cases, however some of its limitations or ambiguities on how to
+apply it to covalent semiconductors have been pointed out recently [K.-H. Xue
+et al., Comput. Mater. Science 153, 493 (2018)]. In this work, we investigate
+in detail some of the problems of the DFT-1/2 method with a focus on two
+classes of materials: covalently bonded semiconductors and transition-metal
+oxides. We argue for caution in the application of DFT-1/2 to these materials,
+and the condition to get an improved band gap is a spatial separation of the
+orbitals at the valence band maximum and conduction band minimum.",1901.04800v1
+2019-01-16,Mathematical modelling of Solid Oxide Fuel Cells revisited -- a modified formulation of the problem,"In the paper a mathematical model of the PEN structure (positive electrode -
+electrolyte - negative electrode) of the Solid Oxide Fuel Cell (SOFC) is
+analyzed. It is proved that classical formulation of the problem leads
+inevitably to locally unphysical effects related to negative values of the
+activation overpotential. Moreover, the active layers' thicknesses are shown to
+be components of solution and cannot be predefined in an arbitrary way. A
+modified mathematical formulation of the problem is proposed which includes
+this novelty alongside an amended definition of the activation overpotential. A
+dedicated computational scheme is developed for the cathode sub-problem. The
+accuracy of computations is investigated by means of a newly introduced
+analytical benchmark example. The numerical results obtained for LSCF cathode
+are used to discuss certain aspects of the modified formulation and the active
+layer thickness. The new modelling approach is validated by comparison with
+experimental data.",1901.05509v2
+2019-01-23,"Structure and energetics of carbon-related defects in SiC (0001)/SiO$_{\rm 2}$ systems revealed by first-principles calculations: Defects in SiC, SiO$_{\rm 2}$, and just at their interface","We report first-principles calculations that reveal the atomic forms,
+stability, and energy levels of carbon-related defects in SiC (0001)/SiO$_{\rm
+2}$ systems. We clarify the stable position (SiC side, SiO$_{\rm 2}$ side, or
+just at the SiC/SiO$_{\rm 2}$ interface) of defects depending on the oxidation
+environment. Under an O-rich condition, the di-carbon antisite ((C$_{\rm
+2}$)$_{\rm Si}$) in the SiC side is stable and critical for $n$-channel
+MOSFETs, whereas the di-carbon defect (Si-C-C-Si) at the interface becomes
+critical under an O-poor condition. Our results suggest that the oxidation of
+SiC under a high-temperature O-poor condition is favorable in reducing the
+defects, in consistent with recent experimental reports.",1901.07730v2
+2019-01-25,Self-assembly of a binary mixture of iron oxide nanoparticles in Langmuir film: X-ray scattering study,"In present study we exploited Langmuir technique to produce self-assembled
+arrays composed of monodisperse iron oxide nanoparticles 10 nm and 20 nm in
+diameter and of their binary mixture. A combination of in-situ X-ray
+reflectometry and Grazing-incident small-Angle X-ray scattering was used to
+obtain in-plane and out-of-plane structure of the arrays directly on the water
+surface. Surface pressure isotherms and X-ray reflectometry analysis showed
+that monodisperse 10 nm nanoparticles form a highly ordered monolayer, while 20
+nm particles pack in three-dimensional clusters with a short-range
+(nearest-neighbor) correlations between the particles. In a binary mixture of
+10 nm and 20 nm nanoparticles composed in proportion 3:1 the self-assembly
+process results in a structure where the monolayer of 10 nm particles is
+perturbed by the larger particles. Non-trivial mixing causes an enlargement of
+interparticle distance but keeps the symmetry of two-dimensional lattice of
+smaller nanoparticles. Estimation of the acting interactions and micromagnetic
+simulation suggest the optimal formation for monodisperse and binary ensembles.",1901.08822v1
+2019-02-01,Impact of Polarity on the Anisotropic Diffusion of Conjugated Organic Molecules on (10-10) Zinc Oxide Surface,"We study the influence of polarity on the binding and diffusion of single
+conjugated organic molecules on the inorganic (10-10) zinc oxide surface by
+means of all-atom molecular dynamics simulations at room temperature and above.
+In particular, we consider the effects of partial fluorination of the
+para-sexiphenyl (p-6P) molecule with chemical modifications of one head group
+(p-6PF2) or both (symmetric) head and tail (p-6PF4). Quantum-mechanical and
+classical simulations both result in consistent and highly distinct dipole
+moments and densities of the fluorinated molecules, which interestingly lead to
+a weaker adhesion to the surface than for p-6P. The diffusion for all molecules
+is found to be normal and Arrhenius-like for long times. Strikingly, close to
+room temperature the polar molecules diffuse 1-2 orders of magnitudes slower
+compared to the p-6P reference in the apolar x-direction of the
+electrostatically heterogeneous surface, while in the polar y-direction they
+diffuse 1-2 orders of magnitude faster. We demonstrate that this rather
+unexpected behavior is governed by a subtle electrostatic anisotropic mismatch
+between the polar molecules and the chemically specific surface, as well as by
+increased entropic contributions coming from orientational and internal degrees
+of freedom.",1902.00276v1
+2019-01-02,"Application of image processing in optical method, Moire deflectometry for investigating the optical properties of zinc oxide nanoparticle","Nowadays for measurement of refractive index of nanomaterials usually
+spectro-photometric and mechanical methods are used which are expensive and
+indirect. In this paper for measuring these parameters of zinc oxide
+nanomaterial with two different stabilizers, a simple optical method, Moire
+deflectometry, which is based on wave front analysis and geometric optics is
+used. In the Moire deflectometry method, the beam of light from the laser diode
+passes through the sample. As a result of that, a change in the sample
+environment is observed as deflections of the fringes. By recording of these
+deflections using CCD and image processing with MATLAB, the nanomaterials
+refractive indices can be calculated. Due to the high accuracy of this method
+and improved the image processing code in Matlab, the smallest changes of the
+refractive index in the sample can be measured. Digital Image processing is
+used for processing images in a way that features can be selected and being
+shown. The results obtained in this method show a good improvement over the
+other used methods.",1902.01196v1
+2019-02-05,Cu$_2$O Microcrystals Grown on Silicon as Platform for Quantum-Degenerate Excitons and Rydberg States,"Cuprous oxide (Cu$_2$O) is a semiconductor with large exciton binding energy
+and significant technological importance in applications such as photovoltaics
+and solar water splitting. It is also a superior material system for quantum
+optics that enabled the observation of two intriguing phenomena, i.e. Rydberg
+excitons as solid-state analogue to highly-excited atomic states and dense
+exciton gases showing quantum degeneracy when approaching the phase transition
+to Bose-Einstein condensation. Previous experiments focused on natural bulk
+crystals due to major difficulties in growing high-quality synthetic samples.
+Here, we present Cu$_2$O microcrystals with excellent optical material quality
+capable of hosting both quantum-degenerate excitons and excited Rydberg states.
+Growth of Cu$_2$O with exceedingly low point defect levels was achieved on
+silicon by a scalable thermal oxidation process compatible with lithographic
+patterning. Using the latter, we demonstrate Rydberg excitons in
+site-controlled Cu$_2$O microstructures, paving the way for a plethora of
+applications in integrated quantum photonics.",1902.01853v1
+2019-02-05,Supercontinuum Generation in Heavy-Metal Oxide Glass Based Suspended-Core Photonic Crystal Fibers,"We investigate supercontinuum generation in several suspended-core soft-glass
+photonic crystal fibers pumped by an optical parametric oscillator tunable
+around 1550 nm. The fibers were drawn from lead-bismuth-gallium-cadmium-oxide
+glass (PBG-81) with a wide transmission window from 0.5-2.7 micron and a high
+nonlinear refractive index up to 4.3.10^(-19) m^2/W. They have been
+specifically designed with a microscale suspended hexagonal core for efficient
+supercontinuum generation around 1550 nm. We experimentally demonstrate two
+supercontinuum spectra spanning from 1.07-2.31 micron and 0.89-2.46 micron by
+pumping two PCFs in both normal and anomalous dispersion regimes, respectively.
+We also numerically model the group velocity dispersion curves for these fibers
+from their scanning electron microscope images. Results are in good agreement
+with numerical simulations based on the generalized nonlinear Schrodinger
+equation including the pump frequency chirp.",1902.02385v1
+2019-02-11,Improved oxidation resistance of high emissivity coatings on fibrous ceramic for reusable space system,"To develop high emissivity coatings on fibrous ceramic substrates with
+improved thermal resistance for reusable space systems,
+WSi2-MoSi2-Si-SiB6-borosilicate glass coatings were prepared on fibrous ZrO2 by
+slurry dipping and subsequent high temperature rapid sintering. A coating with
+50 wt% WSi2 and 50 wt% MoSi2 presents optimal thermal stability with only 10.06
+mg/cm2 mass loss and 4.0 % emissivity decrease in the wavelength regime of 1.27
+to 1.73 microns after 50 h oxidation at 1773 K. The advantages of double phase
+metal silicide coatings combining WSi2 and MoSi2 include improved thermal
+compatibility with the substrate and an enhanced glass mediated self healing
+ability.",1902.03943v2
+2019-02-11,Small Polarons in Transition Metal Oxides,"The formation of polarons is a pervasive phenomenon in transition metal oxide
+compounds, with a strong impact on the physical properties and functionalities
+of the hosting materials. In its original formulation the polaron problem
+considers a single charge carrier in a polar crystal interacting with its
+surrounding lattice. Depending on the spatial extension of the polaron
+quasiparticle, originating from the coupling between the excess charge and the
+phonon field, one speaks of small or large polarons. This chapter discusses the
+modeling of small polarons in real materials, with a particular focus on the
+archetypal polaron material TiO2. After an introductory part, surveying the
+fundamental theoretical and experimental aspects of the physics of polarons,
+the chapter examines how to model small polarons using first principles schemes
+in order to predict, understand and interpret a variety of polaron properties
+in bulk phases and surfaces. Following the spirit of this handbook, different
+types of computational procedures and prescriptions are presented with specific
+instructions on the setup required to model polaron effects.",1902.04183v2
+2019-02-14,Indium tin oxide nanoparticle:TiO$_{2}$:air layers for one-dimensional multilayer photonic structures,"In this work we study the optical properties, by means of the transfer matrix
+method, of one-dimensional photonic crystals in which layers of silica
+nanoparticles are alternated with layers of indium tin oxide nanoparticle (ITO)
+/ titania nanoparticle mixture. The dielectric function of the mixed
+ITO/TiO$_{2}$ nanoparticle layer is carefully accounted for with a generalized
+Rayleigh equation for the ternary mixture ITO:TiO$_{2}$:air. We have studied
+the light transmission of the multilayer photonic crystal as a function of the
+ITO/TiO$_{2}$ ratio. We observe that, by increasing the ITO content in the
+three-phase mixture, the intensity of the plasmon resonance in the near
+infrared (NIR) increases and the intensity of the photonic band gap (visible)
+decreases. Thus, our study is of major importance for the realization of
+electrochromic smart windows, in which separate and independent NIR and visible
+light control is required.",1902.05353v1
+2019-02-14,Epitaxial Integration on Si(001) of Ferroelectric Hf0.5Zr0.5O2 Capacitors with High Retention and Endurance,"Epitaxial ferroelectric Hf0.5Zr0.5O2 films have been successfully integrated
+in a capacitor heterostructure on Si(001). The orthorhombic Hf0.5Zr0.5O2 phase,
+[111] out-of-plane oriented, is stabilized in the films. The films present high
+remnant polarization Pr close to 20 {\mu}C/cm2, rivaling with equivalent
+epitaxial films on single crystalline oxide substrates. Retention time is
+longer than 10 years for writing field of around 5 MV/cm, and the capacitors
+show endurance up to 1E9 cycles for writing voltage of around 4 MV/cm. It is
+found that the formation of the orthorhombic ferroelectric phase depends
+critically on the bottom electrode, being achieved on La0.67Sr0.33MnO3 but not
+on LaNiO3. The demonstration of excellent ferroelectric properties in epitaxial
+films of Hf0.5Zr0.5O2 on Si(001) is relevant towards fabrication of devices
+that require homogeneity in the nanometer scale, as well as for better
+understanding of the intrinsic properties of this promising ferroelectric
+oxide.",1902.05504v1
+2019-03-19,Metal to insulator transition in Conducting Polyaniline/Graphene Oxide composites,"Broadband Dielectric Spectroscopy (BDS) measurements of
+P{\omicron}lyaniline/Graphene oxide composites were conducted for an
+as-prepared and a thermally annealed specimen, respectively, from 15K to room
+temperature. Electrical conductivity values of the annealed composite display a
+very modest rise denoting the important contributions of the GO component to
+achieving electrical stability of the polymer. Patterns of the dc conductivity
+as a function of temperature also reveal a metal to insulator transition around
+75K. The transition is dominated by two key factors; temperature and annealing
+process. Metal-like and insulating features are subsequently detected, as well,
+and accordingly described to provide a qualitative inspection of the charge
+transfer mechanisms involved",1903.07954v2
+2019-03-26,"Oxygen atom reactions with C2H6, C2H4, and C2H2 in ices","Oxygen atom addition and insertion reactions may provide a pathway to
+chemical complexity in ices that are too cold for radicals to diffuse and
+react. We have studied the ice-phase reactions of photo-produced oxygen atoms
+with C2 hydrocarbons under ISM-like conditions. The main products of oxygen
+atom reactions with ethane are ethanol and acetaldehyde; with ethylene are
+ethylene oxide and acetaldehyde; and with acetylene is ketene. The derived
+branching ratio from ethane to ethanol is ~0.74 and from ethylene to ethylene
+oxide is ~0.47. For all three hydrocarbons there is evidence of an effectively
+barrierless reaction with O(^1D) to form oxygen-bearing organic products; in
+the case of ethylene, there may be an additional barriered contribution of the
+ground-state O(^3P) atom. Thus, oxygen atom reactions with saturated and
+unsaturated hydrocarbons are a promising pathway to chemical complexity even at
+very low temperatures where the diffusion of radical species is thermally
+inaccessible.",1903.10981v1
+2019-03-28,Atomistic manipulation of reversible oxidation and reduction in Ag by electron beam,"Employing electrons for direct control of nanoscale reaction is highly
+desirable since it provides fabrication of nanostructures with different
+properties at atomic resolution and with flexibility of dimension and location.
+Here, applying in situ transmission electron microscopy, we show the reversible
+oxidation and reduction kinetics in Ag, well controlled by changing the dose
+rate of electron beam. Aberration-corrected high-resolution transmission
+electron microscopy observation reveals that O atoms are preferably inserted
+and extracted along the {111} close-packed planes of Ag, leading to the
+nucleation and decomposition of nanoscale Ag2O islands on the Ag substrate. By
+controlling electron beam size and dose rate, we demonstrated fabrication of an
+array of 3 nm Ag2O nanodots in an Ag matrix. Our results open up a new pathway
+to manipulate atomistic reaction with electron beam towards the precise
+fabrication of nanostructures for device applications.",1903.12038v1
+2019-03-28,Vertical Organic Thin-Film Transistor with Anodized Permeable Base for Very Low Leakage Current,"The Organic Permeable Base Transistor (OPBT) is currently the fastest organic
+transistor with a transition frequency of 40 MHz. It relies on a thin aluminum
+base electrode to control the transistor current. This electrode is surrounded
+by a native oxide layer for passivation, currently created by oxidation in air.
+However, this process is not reliable and leads to large performance variations
+between samples, slow production and relatively high leakage currents. Here, we
+demonstrate for the first time that electrochemical anodization can be
+conveniently employed for the fabrication of high performance OPBTs with vastly
+reduced leakage currents and more controlled process parameters. Very large
+transmission factors of 99.9996% are achieved, while excellent on/off ratios of
+5x10$^5$ and high on-currents greater than 300 mA/cm$^2$ show that the C$_{60}$
+semiconductor layer can withstand the electrochemical anodization. These
+results make anodization an intriguing option for innovative organic transistor
+design.",1903.12047v2
+2019-04-05,Water oxidation catalysis on reconstructed NaTaO$_3$ (001) surfaces,"Polar perovskite oxide surfaces are subject to structural reconstruction as a
+possible stabilisation mechanisms, which changes the surface structure and
+hence the surface chemistry. To investigate this effect, we study the oxygen
+evolution reaction (OER) on the reconstructed (001) surface of NaTaO$_3$, by
+means of density functional theory (DFT) calculations and compare it with the
+non-polar (113) surface of the same material. For the clean surface the
+reconstruction has a beneficial effect on the catalytic activity, lowering the
+minimal overpotential from 0.88 V to 0.70 V while also changing the most active
+reaction site from Na to Ta. Under photocatalytic conditions, the Ta sites are
+covered by oxygen adsorbates, rendering a lattice oxygen site on the NaO
+terrace the most active with a very low overpotential of 0.32 V. An alternative
+surface reconstruction stable in contact with water leads to an oxygen coupling
+mechanism with an overpotential of 0.52 V. Our results show that terraced
+surface reconstructions enable novel reaction pathways with low overpotentials
+that do not exist on other non-polar NaTaO$_3$ surfaces nor on non-polar
+surfaces of chemically similar materials such as SrTaO$_2$N.",1904.03070v1
+2019-03-23,Photon Management for Silicon Solar Cells featuring Hole-Selective Molybdenum Oxide Rear Contacts: An Optical Simulation Study,"Passivated, hole-selective contacts play important role in reducing surface
+recombination by lowering the concentration of electrons in the rear side of a
+solar cell. However, parasitic optical losses in these contacts can still limit
+the performance of the cell. In this work, the long wavelength optical losses
+of silicon solar cells featuring hole-selective molybdenum oxide (MoOx) rear
+contacts are investigated using optical simulations. The potential of these
+selective contacts for possible enhancement of photogenerated current density
+was also investigated for their use with nanostructured dielectric layers.",1904.04210v2
+2019-04-23,"Real-time observation of electronic, vibrational, and rotational dynamics in nitric oxide with attosecond soft X-ray pulses at 400 eV","Photoinduced quantum dynamics in molecules have hierarchical temporal
+structures with different energy scales that are associated with electron and
+nuclear motions. Femtosecond-to-attosecond transient absorption spectroscopy
+(TAS) using high-harmonic generation (HHG) with a photon energy below 300 eV
+has been a powerful tool to observe such electron and nuclear dynamics in a
+table-top manner. However, comprehensive measurements of the electronic,
+vibrational, and rotational molecular dynamics have not yet been achieved.
+Here, we demonstrate HHG-based TAS at the nitrogen K-edge (400 eV) for the
+first time, and observe all the electronic, vibrational, and rotational degrees
+of freedom in a nitric oxide molecule at attosecond to sub-picosecond time
+scales. This method of employing core-to-valence transitions offers an
+all-optical approach to reveal complete molecular dynamics in photochemical
+reactions with element and electronic state specificity.",1904.10456v2
+2019-04-30,Two-dimensional honeycomb borophene oxide: A promising anode material offering super high capacity for Li/Na-ion batteries,"Rational design of novel two-dimensional (2D) electrode materials with high
+capacity is crucial for the further development of Li-ion and Na-ion batteries.
+Herein, based on first-principles calculations, we systemically investigate Li
+and Na storage behaviors in the recently discovered 2D topological nodal-loop
+metal - the honeycomb borophene oxide (h-B2O). We show that h-B2O is an almost
+ideal anode material. It has good conductivity before and after Li/Na
+adsorption, fast ion diffusion with diffusion barrier less than 0.5 eV, low
+open-circuit voltage (less than 1 V), and small lattice change (less than 6.2%)
+during intercalation. Most remarkably, its theoretical storage capacity is
+extremely high, reaching up to 2137 mAh/g for Li and 1425 mAh/g for Na. Its Li
+storage capacity is more than six times higher than graphite (372 mAh/g), and
+is actually the highest among all 2D materials discovered to date. Our results
+strongly suggest that 2D h-B2O is an exceedingly promising anode material for
+both Li- and Na-ion batteries with super high capacity.",1904.13084v1
+2019-08-01,Enhanced ambient stability of exfoliated black phosphorus by passivation with nickel nanoparticles,"Since its discovery, the environmental instability of exfoliated black
+phosphorus (2D bP) has emerged as a challenge that hampers its wide application
+in chemistry, physics, and materials science. Many studies have been carried
+out to overcome this drawback. Here we show a relevant enhancement of ambient
+stability in few-layer bP decorated with nickel nanoparticles as compared to
+pristine bP. In detail, the behavior of the Ni-functionalized material exposed
+to ambient conditions in the dark is accurately studied by TEM (Transmission
+Electron Microscopy), Raman Spectroscopy, and high resolution X-ray
+Photoemission and Absorption Spectroscopy. These techniques provide a
+morphological and quantitative insight of the oxidation process taking place at
+the surface of the bP flakes. In the presence of Ni NPs, the decay time of 2D
+bP to phosphorus oxides is more than three time slower compared to pristine bP,
+demonstrating an improved structural stability within twenty months of
+observation.",1908.00237v1
+2019-08-13,Investigating the real-time dissolution of a compositionally complex alloy using inline ICP and correlation with XPS,"The real-time dissolution of the single-phase compositionally complex alloy
+(CCA), Al1.5TiVCr, was studied using an inline inductively coupled plasma
+method. Compositionally complex alloys (CCAs), a term encompassing high entropy
+alloys (HEAs) or multi-principal element alloys (MPEAs), are - in general -
+noted for their inherently high corrosion resistance. In order to gain an
+insight into the dissolution of Al1.5TiVCr alloy, atomic emission
+spectroelectrochemistry was utilised in order to measure the ion dissolution of
+the alloy during anodic polarisation. It was revealed that incongruent
+dissolution occurred, with preferential dissolution of Al, and essentially no
+dissolution of Ti, until the point of alloy breakdown. Results were correlated
+with X-ray photoelectron spectroscopy, which revealed a complex surface oxide
+inclusive of unoxidised metal, and metal oxides in disproportion to the bulk
+alloying element ratio.",1908.04493v1
+2019-08-14,Comparison of aluminum oxide empirical potentials from cluster to nanoparticle,"Aluminum oxide nanoparticles are increasingly sought in numerous
+technological applications. However, as the nanoparticles grow during the
+synthesis, two phase transitions occur. At the nanoscale, numerical simulation
+of the stability of the alumina phases requires the use of empirical potentials
+that are reliable over a large range of system sizes going from a few atoms to
+several hundred thousand atoms. In this work, we confronted four different
+empirical potentials that are currently employed for bulk alumina. We found
+that only two of them are correct at the molecular level when compared to DFT
+calculations. Furthermore, the two potentials remain the best at the nanoscale
+as they reproduce one or two phase transitions that were observed
+experimentally: from amorphous solid to cubic crystal ({\gamma}) and from cubic
+to hexagonal ({\alpha}, i.e. corundum) crystal.",1908.05046v2
+2019-08-16,"Influence of annealing temperature on the structural, topographical and optical properties of sol gel derived ZnO thin films","This investigation deals with the effect of annealing temperature on the
+structural, topographical and optical properties of Zinc Oxide thin films
+prepared by sol gel method. The structural properties were studied using X-ray
+diffraction and the recorded patterns indicated that all the films had a
+preferred orientation along (002) plane and the crystallinity along with the
+grain size were augmented with annealing temperature. The topographical
+modification of the films due to heat treatment was probed by atomic force
+microscopy which revealed that annealing roughened the surface of the film. The
+optical properties were examined by a UV visible spectrophotometer which
+exhibited that maximum transmittance reached nearly 90% and it diminished with
+increasing annealing temperature.",1908.05886v1
+2019-08-16,"An sp-hybridized molecular carbon allotrope, cyclo[18]carbon","Carbon allotropes built from rings of two-coordinate atoms, known as
+cyclo[n]carbons, have fascinated chemists for many years, but until now they
+could not be isolated or structurally characterized, due to their high
+reactivity. We generated cyclo[18]carbon (C18) using atom manipulation on
+bilayer NaCl on Cu(111) at 5 Kelvin by eliminating carbon monoxide from a
+cyclocarbon oxide molecule C24O6. Characterization of cyclo[18]carbon by
+high-resolution atomic force microscopy revealed a polyynic structure with
+defined positions of alternating triple and single bonds. The high reactivity
+of cyclocarbon and cyclocarbon oxides allows covalent coupling between
+molecules to be induced by atom manipulation, opening an avenue for the
+synthesis of other carbon allotropes and carbon-rich materials from the
+coalescence of cyclocarbon molecules.",1908.05904v1
+2019-08-20,Dissipative dynamics of atomic and molecular Rydberg gases: Avalanche to ultracold plasma states of strong coupling,"Not long after metastable xenon was photoionized in a magneto-optical trap,
+groups in Europe and North America found that similar states of ionized gas
+evolved spontaneously from state-selected, high principal quantum number
+Rydberg gases. Studies of atomic xenon and molecular nitric oxide entrained in
+a supersonically cooled molecular beam subsequently showed much the same final
+state evolved from a sequence of prompt Penning ionization and electron-impact
+avalanche to plasma, well-described by coupled rate-equation simulations. But,
+measured over longer times, the molecular ultracold plasma was found to exhibit
+an anomalous combination of very long lifetime and very low apparent electron
+temperature. This review summarizes early developments in the study of
+ultracold plasmas formed by atomic and molecular Rydberg gases, and then
+details observations as they combine to characterize properties of the nitric
+oxide molecular ultracold plasma that appear to call for an explanation beyond
+the realm of conventional plasma physics.",1908.07633v1
+2019-11-08,Core-level x-ray photoemission and Raman spectroscopy studies on electronic structures in Mott-Hubbard type nickelate oxide NdNiO$_2$,"We perform core-level X-ray photoemission spectroscopy (XPS) and electronic
+Raman scattering studies of electronic structures and spin fluctuations in the
+bulk samples of the nickelate oxide NdNiO$_2$. According to Nd $3d$ and O $1s$
+XPS spectra, we conclude that NdNiO$_2$ has a large transfer energy. From the
+analysis of the main line of the Ni $2p_{3/2}$ XPS, we confirm the NiO$_2$
+planes in NdNiO$_2$ are of Mott-Hubbard type in the Zaanen-Sawatzky-Allen
+scheme. The two-magnon peak in the Raman scattering provides direct evidence
+for the strong spin-fluctuation in NdNiO$_2$. The peak position determines the
+antiferromagnetic exchange $J=25$~meV. Our experimental results agree well with
+our previous theoretical results.",1911.03177v2
+2019-11-10,Epitaxial stabilization of ultra thin films of high entropy perovskite,"High entropy oxides (HEOs) are a class of materials, containing equimolar
+portions of five or more transition metal and/or rare-earth elements. We report
+here about the layer-by-layer growth of HEO
+[(La$_{0.2}$Pr$_{0.2}$Nd$_{0.2}$Sm$_{0.2}$Eu$_{0.2}$)NiO$_3$] thin films on
+NdGaO$_3$ substrates by pulsed laser deposition. The combined characterizations
+with in-situ reflection high energy electron diffraction, atomic force
+microscopy, and X-ray diffraction affirm the single crystalline nature of the
+film with smooth surface morphology. The desired +3 oxidation of Ni has been
+confirmed by an element sensitive X-ray absorption spectroscopy measurement.
+Temperature dependent electrical transport measurements revealed a first order
+metal-insulator transition with the transition temperature very similar to the
+undoped NdNiO$_3$. Since both of these systems have a comparable tolerance
+factor, this work demonstrates that the electronic behaviors of $A$-site
+disordered perovskite-HEOs are primarily controlled by the average tolerance
+factor.",1911.03866v1
+2019-11-16,Exploiting Oxide Based Resistive RAM Variability for Bayesian Neural Network Hardware Design,"Uncertainty plays a key role in real-time machine learning. As a significant
+shift from standard deep networks, which does not consider any uncertainty
+formulation during its training or inference, Bayesian deep networks are being
+currently investigated where the network is envisaged as an ensemble of
+plausible models learnt by the Bayes' formulation in response to uncertainties
+in sensory data. Bayesian deep networks consider each synaptic weight as a
+sample drawn from a probability distribution with learnt mean and variance.
+This paper elaborates on a hardware design that exploits cycle-to-cycle
+variability of oxide based Resistive Random Access Memories (RRAMs) as a means
+to realize such a probabilistic sampling function, instead of viewing it as a
+disadvantage.",1911.08555v5
+2019-11-21,Crystallization of Cuprous Oxide Thin Films by Continuous-Wave Laser Diode with Micro-Chevron Laser Beam (μ-CLB),"Crystallization of thin film materials by exploiting laser induced
+crystallization has been advancing for the past four decades. This unique thin
+film technique has been predominantly used in processing thin film materials
+made of a single chemical element; however, harnessing this technique to extend
+its use for thin film materials containing multiple chemical elements (e.g.,
+metal oxides) unlocks applications currently not accessible. In this study,
+laser crystallization of a Cu2O strip was demonstrated. A continuous-wave laser
+diode with a micrometer-scale chevron-shaped beam profile (micro chevron laser
+beam) was used to crystallize CuO thin films covered with an amorphous carbon
+(a-C) cap layer, deposited on fused silica substrates. Electron backscatter
+diffraction, Raman spectroscopy, photoluminescence spectroscopy, and UV-Vis
+spectroscopy were used to investigate the crystallinity and optical properties
+of the Cu2O thin films revealing their unique characteristics associated with
+the crystallization process.",1911.09778v1
+2019-11-21,Is density functional theory accurate for lytic polysaccharide monooxygenase enzymes?,"The lytic polysaccharide monooxygenase (LPMO) enzymes boost polysaccharide
+depolymerization through oxidative chemistry, which has fueled the hope for
+more energy-efficient production of biofuel. We have recently proposed a
+mechanism for the oxidation of the polysaccharide substrate (Hedeg{\aa}rd &
+Ryde, Chem. Sci. 2018, 9, 3866). In this mechanism, complexes with superoxide,
+oxyl, as well as hydroxyl (i.e. [CuO2]+, [CuO]+ and [CuOH]2+) cores were
+involved. These complexes can have both singlet and triplet spin states, and
+both spin-states may be important for how LPMOs function during catalytic
+turnover. Previous calculations on LPMOs have exclusively been based on density
+functional theory (DFT). However, different DFT functionals are known to
+display large differences for spin-state splittings in transition-metal
+complexes, and this has also been an issue for LPMOs. In this paper, we study
+the accuracy of DFT for spin-state splittings in superoxide, oxyl, and hydroxyl
+intermediates involved in LPMO turnover. As reference we employ
+multiconfigurational perturbation theory (CASPT2).",1911.09780v2
+2019-11-25,Externally driven local colloidal ordering induced by a point-like heat source,"We study here how phase transitions are induced in colloidal suspensions by a
+point-like heat source, an optically trapped metal oxide particle absorbing
+light. We find that thermophoresis increases the number density of colloids
+around the oxide particle, leading to the appearance of solid clusters. Our
+analysis based on thermophoresis reveals that the solid-fluid interface
+position is purely determined by the relationship of the particle concentration
+profile in the fluid state with the volume fraction of the phase transition,
+and no other effect of thermodynamics is seen in the cluster sizes. In this
+system, we observe the formation of face-centered cubic crystals, amorphous
+states, and structures with icosahedral order. This shows a rich possibility of
+non-trivial orderings under spatially controlled heterogeneous growth in
+external ""semi-soft"" potentials that are softer than walls but with substantial
+variations at the scale of a few particle diameters. Because of the tuneable
+rate of addition of particles to the clusters, we propose this method could be
+used to study the complex interplay of densification with local spatial
+confinement effects, kinetics, and ordering.",1911.10759v1
+2019-12-03,Enhancing the understanding of hydrogen evolution and oxidation reaction on Pt(111) through ab initio simulations on electrode/electrolyte kinetics,"The hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER)
+play an important role in hydrogen based energy conversion. Recently, the
+frustrating performance in alkaline media raised debates on the relevant
+mechanism, especially on the role of surface hydroxyl (OH*). We present a full
+pH range electrode/electrolyte kinetics simulation for HER/HOR on Pt(111), with
+the potential-related rate constants been calculated with density functional
+theory methods. The polarization curves agree well with the experimental
+observations. The stability of OH* is found to be unlikely an effective
+activity descriptor since it is irrelevant to the onset potential of HOR/HER.
+Degree of rate control analyses reveal that the alkaline current is controlled
+jointly by Tafel and Volmer steps, while the acidic current solely by Tafel
+step, which explains the observed pH-dependent kinetics. Therefore, it is also
+possible to reduce the overpotential of alkaline HER/HOR by accelerating the
+Tafel step besides tuning the hydrogen binding energy.",1912.01152v1
+2019-12-06,Vertically-Oriented Graphene Oxide Membranes for High-Performance Osmotic Energy Conversion,"Reverse electrodialysis is a promising method to harvest the osmotic energy
+stored between seawater and freshwater, but it has been a long-standing
+challenge to fabricate permselective membranes with the power density
+surpassing the industry benchmark of 5.0 W $m^{-2}$ for half a century. Herein,
+we report a vertically-oriented graphene oxide membranes (V-GOMs) with the
+combination of high ion selectivity and ultrafast ion permeation, whose
+permeation is three orders of magnitude higher than the extensively studied
+horizontally stacked GOMs (H-GOMs). By mixing artificial seawater and river
+water, we obtained an unprecedented high output power density of 10.6 W
+$m^{-2}$, outperforming all existing materials. Molecular dynamics (MD)
+simulations reveal the mechanism of the ultrafast transport in V-GOMs results
+from the quick entering of ions and the large accessible area as well as the
+apparent short diffusion paths in V-GOMs. These results will facilitate the
+practical application of osmotic energy and bring innovative design strategy
+for various systems involving ultrafast transport, such as filtration and
+catalysis.",1912.03093v1
+2019-12-12,A numerical ellipsometric analysis (NEA) of nanoscale layered systems,"A simple and robust method able to predict, with high accuracy, the optical
+properties of single and multi-layer nanostructures is presented. The method
+exploits a COMSOL Multiphysics simulation platform and it has been validated by
+three case studies with increasing numerical complexity: i) a single thin layer
+(20 nm) of Ag deposited on a glass substrate; ii) a metamaterial composed of
+five bi-layers of Ag/ITO (Indium Tin Oxide), with a thickness of 20 nm each;
+iii) a system based on a three-materials unit cell (AZO/ITO/Ag), but without
+any thickness periodicity (AZO stands for Al$_2$O$_3$/Zinc Oxide). Numerical
+results have been compared with experimental data provided by real
+ellipsometric measurements performed on the above mentioned nanostructures
+ad-hoc fabricated. The obtained agreement is excellent suggesting this research
+as a valid approach to design materials able to work in a broad spectrum range.",1912.05717v1
+2019-12-13,The use of strain and grain boundaries to tailor phonon transport properties: A first principles study of 2H-phase $CuAlO_{2}$ (Part II),"Transparent oxide materials, such as $CuAlO_{2}$, a p-type transparent
+conducting oxide (TCO), have recently been studied for high temperature
+thermoelectric power generators and coolers for waste heat. TCO materials are
+generally low cost and non-toxic. The potential to engineer them through strain
+and nano-structuring are two promising avenues toward continuously tuning the
+electronic and thermal properties to achieve high zT values and low cost/kW-hr
+devices. In this work, the strain-dependent lattice thermal conductivity of 2H
+$CuAlO_{2}$ is computed by solving the phonon Boltzmann transport equation with
+interatomic force constants extracted from first-principles calculations. While
+the average bulk thermal conductivity is around 32 W/(K-m) at room temperature,
+it drops to between 5-15 W/(K-m) for typical experimental grain sizes from 3nm
+to 30nm at room temperature. We find that strain can offer both an increase as
+well as a decrease in the thermal conductivity as expected, however the overall
+inclusion of small grain sizes dictates the potential for low thermal
+conductivity in this material.",1912.06595v1
+2019-12-18,Metal-oxide interface reactions and their effect on integrated resistive/threshold switching in NbOx,"Reactive metal electrodes (Nb, Ti, Cr, Ta, and Hf) are shown to play an
+important role in controlling the volatile switching characteristics of
+metal/Nb2O5/Pt devices. In particular, devices are shown to exhibit stable
+threshold switching under negative bias but to have a response under positive
+bias that depends on the choice of metal. Three distinct responses are
+highlighted: Devices with Nb and Ti top electrodes are shown to exhibit stable
+threshold switching with symmetric characteristics for both positive and
+negative polarities; devices with Cr top electrodes are shown to exhibit stable
+threshold switching but with asymmetric hysteresis windows under positive and
+negative polarities; and devices with Ta and Hf electrodes are shown to exhibit
+an integrated threshold-memory (1S1M) response. Based on thermodynamic data and
+lumped element modelling these effects are attributed to the formation of a
+metal-oxide interlayer and its response to field-induced oxygen exchange. These
+results provide important insight into the physical origin of the switching
+response and pathways for engineering devices with reliable switching
+characteristics.",1912.08373v1
+2019-12-20,Mott and spin-Peierls physics in TiPO$_4$ under high pressure,"TiPO$_4$ is a Mott insulator and one of few inorganic compounds featuring a
+spin-Peierls phase at low temperature. Recent experimental studies have
+suggested the presence of spin-Peierls dimerization also at ambient temperature
+though at high pressure. Here, we present a combined experimental and
+theoretical study of the energetics of the high-pressure phase. We analyse
+dimerization properties and their coupling to spin degrees of freedom. Most
+importantly, we argue that TiPO$_4$ resents a direct analogue to the celebrated
+binary transition metal oxide VO$_2$. TiPO$_4$ allows to assess spin-dimer
+physics in the high-pressure regime in a controlled fashion, having the
+potential to become an important model system representative of the class of
+dimerized transition metal oxides.",1912.09692v1
+2019-12-29,Epitaxial antiperovskite/perovskite heterostructures for materials design,"We demonstrate fabrication of atomically sharp interfaces between nitride
+antiperovskite Mn$_{3}$GaN and oxide perovskites
+(La$_{0.3}$Sr$_{0.7}$)(Al$_{0.65}$Ta$_{0.35}$)O$_{3}$ (LSAT) and SrTiO$_{3}$ as
+paradigms of nitride-antiperovskite/oxide-perovskite heterostructures. Using a
+combination of scanning transmission electron microscopy (STEM),
+atomic-resolution spectroscopic techniques, and first-principle calculations,
+we investigated the atomic-scale structure, composition, and boding at the
+interface. We show that the epitaxial growth between the antiperovskite and
+perovskite compounds is mediated by a coherent interfacial monolayer that
+connects the two anti-structures. We anticipate our results to be a major step
+for the development of functional antiperovskite/perovskite heterostructures
+opening to harness a combination of their functional properties including
+topological properties for ultra low power applications.",1912.12583v1
+2020-03-01,Bi2W2O9: a potentially antiferroelectric Aurivillius phase,"Ferroelectric tungsten-based Aurivillius oxides are naturally stable
+superlattice structures, in which A-site deficient perovskite blocks
+[WnO3n+1]-2 (n = 1, 2, 3, ...) interleave with fluorite-like bismuth oxide
+layers [Bi2O2]+2 along the c -axis. In the n = 2 Bi2W2O9 phase, an in-plane
+antipolar distortion dominates but there has been controversy as to the ground
+state symmetry. Here we show, using a combination of first-principles density
+functional theory calculations and experiments, that the ground state is a
+non-polar phase of Pnab symmetry. We explore the energetics of metastable
+phases and the potential for antiferroelectricity in this n=2 Aurivillius
+phase.",2003.00486v1
+2020-03-06,Indium tin oxide films meet circular Rydberg atoms: prospects for novel quantum simulation schemes,"Long-lived circular Rydberg atoms are picking up increasing interest for
+boosting coherence times in Rydberg-based quantum simulation. We elaborate a
+novel approach to stabilize circular Rydberg states against spontaneous and
+blackbody-induced decay using a suppression capacitor made from indium tin
+oxide (ITO) thin films, which combine reflection of microwaves with
+transparency in the visible spectral range. To this end, we perform detailed
+characterization of such films using complementary spectroscopic methods at GHz
+and THz frequencies and identify conditions that allow for reaching
+circular-state lifetimes up to tens of milliseconds in a room-temperature
+environment. We discuss prospects of our findings in view of the quest for
+quantum simulations with high-$n$ circular Rydberg states at room temperature.",2003.03161v3
+2020-03-16,Signature of band inversion in the perovskite thin-film alloys BaSn$_{1-x}$Pb$_x$O$_3$,"Perovskite oxides ABO$_3$ containing heavy B-site elements are a class of
+candidate materials to host topological metals with a large spin-orbit
+interaction. In contrast to the band insulator BaSnO$_3$, the semimetal
+BaPbO$_3$ is proposed to be a typical example with an inverted band structure,
+the conduction band of which is composed of mainly the O-2p orbital. In this
+study, we exemplify a band-gap modification by systematic structural, optical,
+and transport measurements in BaSn$_{1-x}$Pb$_x$O$_3$ films. A sudden
+suppression of the conductivity and an enhancement of the weak antilocalization
+effect at $x$ = 0.9 indicate the presence of a singular point in the electronic
+structure as a signature of the band inversion. Our findings provide an
+intriguing platform for combining topological aspects and electron correlation
+in perovskite oxides based on band-gap engineering.",2003.07181v1
+2020-03-17,Number Parity effect in the normal state of $SrTiO_3$,"We study the recently discovered even-odd effects in the normal state of
+single-electron devices manufactured at strontium titanium oxide/lanthanum
+aluminum oxide interfaces (STO/LAO). Within the framework of the number
+parity-projected formalism and a phenomenological fermion-boson model we find
+that, in sharp contrast to conventional superconductors, the crossover
+temperature $T^*$ for the onset of number parity effect is considerably larger
+than the superconducting transition temperature $T_c$ due to the existence of a
+pairing gap above $T_c$. Furthermore, the finite lifetime of the preformed
+pairs reduces by several orders of magnitude the effective number of states
+$N_{\rm eff}$ available for the unpaired quasiparticle in the odd parity state
+of the Coulomb blockaded STO/LAO island. Our findings are in qualitative
+agreement with the experimental results reported by Levy and coworkers for
+STO/LAO based single electron devices.",2003.07479v3
+2020-03-17,The role of silanol nests in the activation of the [Fe=O]2+ group in the reaction of hydrogen atom transfer from methane,"Silanol nests can play the role of places into which positively charged
+groups, such as, [FeO]2+, can invade. In the framework of this work, the
+influence of such structures on the activity of the [FeO]2+ group in the
+reaction of detachment of a hydrogen atom from methane was considered. Two ways
+of the reaction of hydrogen atom transfer (HAT) from methane were found: the
+so-called ferryl and oxyl routes. It was shown that the reaction of the
+detachment of a hydrogen atom from methane, which is a limiting stage of the
+oxidation of methane to methanol at the alpha center, proceeds through the
+formation of the so-called oxidation state [Fe(III)-O(-)]2+, and fingerprint of
+this state is negative spin density on oxo moiety.",2003.07565v1
+2020-03-19,"Universal relationship between the energy scales of the pseudogap phase, the superconducting state and the charge density wave order in copper oxide superconductors","We report the hole doping dependencies of the pseudogap phase energy scale,
+$2\Delta_{\rm PG}$, the anti-nodal (nodal) superconducting energy scales
+$2\Delta^{AN}_{\rm SC}$ ($2\Delta^{N}_{\rm SC}$) and the charge density wave
+energy scale, $2\Delta_{\rm CDW}$. They have been extracted from the electronic
+Raman responses of distinct copper oxide families. For all the cuprates
+studied, we reveal universal doping dependencies which suggest that
+$2\Delta_{\rm PG}$, $2\Delta^{AN}_{\rm SC}$ and $2\Delta_{\rm CDW}$ are
+governed by common microscopic interactions and that these interactions become
+relevant well above the superconducting transition at $T_c$. In sharp contrast,
+$2\Delta^N_{\rm SC}$ tracks the doping dependence of $T_c$, appearing to be
+controlled by a different kind of interactions than the energy scales above.",2003.08957v2
+2020-03-22,Light-driven permanent transition from insulator to conductor in Ga2O3,"The transition from insulator to conductor can be achieved in some materials
+but requires modification of both the arrangement of atoms and their electronic
+configurations. This is often achieved by doping. Here we reveal a mechanism
+the lattice may adopt to induce such a transition. We show that limited
+exposure to sub-bandgap light caused a permanent transition from an insulator
+state to a conductor state in the insulating oxide Ga2O3 with 9-orders of
+magnitude increase in electronic conduction. Photoexcitation modifies the
+charge state of an O-vacancy and the redistribution of the localized electrons,
+leading to a massive structural distortion in the lattice that is shown to be
+the underlying mechanism. It modifies density of states and introduces new
+stable states with shallower energy levels, leading to this intriguing
+behavior. We suggest that this mechanism may occur in other wide bandgap metal
+oxides leading to drastic modification in their electronic properties.",2003.09954v1
+2020-03-25,Universal Gelation of Metal Oxide Nanocrystals via Depletion Attractions,"Nanocrystal gelation provides a powerful framework to translate nanoscale
+properties into bulk materials and to engineer emergent properties through the
+assembled microstructure. However, many established gelation strategies rely on
+chemical reactions and specific interactions, e.g., stabilizing ligands or ions
+on the surface of the nanocrystals, and are therefore not easily transferrable.
+Here, we report a general gelation strategy via non-specific and purely
+entropic depletion attractions applied to three types of metal oxide
+nanocrystals. The gelation thresholds of two compositionally distinct spherical
+nanocrystals agree quantitatively, demonstrating the adaptability of the
+approach for different chemistries. Consistent with theoretical phase behavior
+predictions, nanocrystal cubes form gels at a lower polymer concentration than
+nanocrystal spheres, allowing shape to serve as a handle to control gelation.
+These results suggest that the fundamental underpinnings of depletion-driven
+assembly, traditionally associated with larger colloidal particles, are also
+applicable at the nanoscale.",2003.11633v1
+2020-03-30,"In situ atomic force microscopy depth-corrected 3-dimensional focused ion beam based time-of-flight secondary ion mass spectroscopy: spatial resolution, surface roughness, oxidation","Atomic force microscopy (AFM) is a well-known tool for studying surface
+roughness and to collect depth information about features on the top atomic
+layer of samples. By combining secondary ion mass spectroscopy (SIMS) with
+focused ion beam (FIB) milling in a scanning electron microscope (SEM),
+chemical information of sputtered structures can be visualized and located with
+high lateral and depth resolution. In this paper, a high vacuum (HV) compatible
+AFM has been installed in a TESCAN FIB-SEM instrument that was equipped with a
+time-of-flight secondary ion mass spectroscopy (ToF-SIMS) detector. To
+investigate the crater's depth caused by the ToF-SIMS sputtering, subsequent
+AFM measurements were performed on a multilayer vertical cavity surface
+emitting laser (VCSEL) sample. Surface roughness and milling depth were used to
+aid accurate 3D reconstruction of the sputtered volume's chemical composition.
+Achievable resolution, surface roughness during sputtering and surface
+oxidation issues are analysed. Thus, the integration of complementary detectors
+opens up the ability to determine the sample properties as well as to
+understand the influence of the analysis method on the sample surface during
+the analysis.",2003.13294v1
+2020-04-30,Excitation and characterization of long-lived hydrogenic Rydberg states of nitric oxide,"High Rydberg states of nitric oxide (NO) with principal quantum numbers
+between 40 and 100 and lifetimes in excess of 10 $\mu$s have been prepared by
+resonance enhanced two-color two-photon laser excitation from the X
+$^2\Pi_{1/2}$ ground state through the A $^2\Sigma^+$ intermediate state.
+Molecules in these long-lived Rydberg states were detected and characterized
+126 $\mu$s after laser photoexcitation by state-selective pulsed electric field
+ionization. The laser excitation and electric field ionization data were
+combined to construct two-dimensional spectral maps. These maps were used to
+identify the rotational states of the NO$^+$ ion core to which the observed
+series of long-lived hydrogenic Rydberg states converge. The results presented
+pave the way for Rydberg-Stark deceleration and electrostatic trapping
+experiments with NO, which are expected to shed further light on the decay
+dynamics of these long-lived excited states, and are of interest for studies of
+ion-molecule reactions at low temperatures.",2005.00090v1
+2020-05-02,Mechanical properties of graphene oxide: the impact of functional groups,"In the current study, mechanical characteristics of graphene oxide (GO) as a
+promising substitute of graphene are systematically studied through molecular
+dynamics simulation. For this purpose, several GO samples having different
+concentrations of epoxide and hydroxyl functional groups are considered. The
+results reveal that increasing the epoxide coverage causes a noticeable
+deterioration in the mechanical characteristics of GO systems. This change is
+correlated with the increase of the formation of ripples in the structure upon
+increasing the epoxide coverage. Moreover, investigating the bond lengths in
+the system, it is concluded that the higher epoxide percentage leads to an
+increase in the length of single and hybrid resonance bonds leading to an
+overall deterioration of the mechanical properties of GO samples. Additionally,
+our results demonstrate that high concentration of functional groups can lead
+to a negative Poisson ratio. Increasing the amount of hydroxyl groups shows the
+same declining effect on the Young modulus. In a graphene system containing
+both epoxide and hydroxyl groups, it is deduced that a higher percentage of the
+former can result in a higher residual strain because of the formation of more
+ripples within the system.",2005.00712v1
+2020-05-08,Surface electronic properties of diamond,"Surface electronic properties of undoped hydrogen terminated diamond covered
+with adsorbates or in electrolyte solutions are summarized. The formation of a
+conductive layer at the surface of diamond is discussed based on Hall effect,
+conductivity, contact potential difference (CPM), scanning electron microscopy
+(SEM), and cyclic voltammetry data applied on homoepitaxially grown CVD diamond
+films with atomically smooth hydrogen terminated surfaces. Due to electron
+transfer from valence band states into empty states of the electrolyte
+(transfer doping), a highly conductive surface layer is generated. Holes
+propagate in the layer with mobilities up to 350 cm2/Vs. The sheet hole density
+is in the range 10^11 to 5x10^12 cm^-2, and dependents on pH of the
+electrolyte. Numerical solutions of the Schrodinger and Poisson equations
+reveal a 2D density of state (DOS) distribution. This has been utilized to
+manufacture ion-sensitive field effect transistors (ISFET). The drain source
+conductivity is pH dependent, with about 66 mV/pH. Application of potentials
+larger than the oxidation threshold of +0.7 V (pH 13) to +1.6 V (pH 1) gives
+rise to strong leakage currents and to partial surface oxidation.",2005.03893v1
+2020-05-18,Spatially-resolved insulator-metal transition for rewritable optical gratings,"Doping is an effective way to tune the property of metal oxides1-5, for
+achieving functional oxide electronics6-8. Previously we developed a
+controllable hydrogen doping technology at ambient conditions by use of
+electron-proton synergistic doping strategy, which enables one to get rid of
+high-temperature/pressure treatments required by traditional technologies9.
+Here, based on this facile doping route, we achieve a visual and reversible
+insulator-metal transition (MIT) for tungsten trioxide (WO3) film. Its
+outstanding spatial selection is comparable to standard UV lithography, which
+shows the potential of becoming a viable way for rewritable WO3 grating device
+fabrication. Furthermore, the period of the obtained WO3 structural grating can
+also be easily changed for requirement by doping area selection. This advanced
+doping technology opens up alternative approaches for developing not only
+optical devices, but also rewritable ions devices and integrated circuits for
+various oxide electronics.",2005.08819v2
+2020-05-28,Studies of thorium and ytterbium ion trap loading from laser ablation for gravity monitoring with nuclear clocks,"Compact and robust ion traps for thorium are enabling technology for the next
+generation of atomic clocks based on a low-energy isomeric transition in the
+thorium-229 nucleus. We aim at a laser ablation loading of single triply
+ionized thorium in a radio-frequency electromagnetic linear Paul trap.
+Detection of ions is based on a modified mass spectrometer and a channeltron
+with single-ion sensitivity. In this study, we successfully created and
+detected 232Th+ and 232Th2+ ions from plasma plumes, studied their yield
+evolution, and compared the loading to a quadrupole ion trap with Yb. We
+explore the feasibility of laser ablation loading for future low-cost 229Th3+
+trapping. The thorium ablation yield shows a strong depletion, suggesting that
+we have ablated oxide layers from the surface and the ions were a result of the
+plasma plume evolution and collisions. Our results are in good agreement with
+similar experiments for other elements and their oxides.",2005.13918v3
+2020-06-06,High-Entropy Oxides Based on Valence Combinations: Design and Practice,"High-entropy oxides (HEOs) are a new class of materials that are promising
+for a wide range of applications. Designing HEOs needs to consider both
+geometric compatibility and electrical equilibrium. However, there is currently
+no available method to systematically consider these two factors when selecting
+constituent materials for making HEOs. Here we propose a two-step strategy,
+where a HEO system to be explored is first partitioned into multiple subsystems
+based on the valence combinations of substituted cations; the geometric
+compatibility is then considered in selecting suitable substituted cations. We
+demonstrate this strategy by using A(5B0.2)O3 perovskite as a model system. We
+show that the system can be partitioned into 12 subsystems. Ten of the
+subsystems have formed a single-phase cubic perovskite, while two have
+partially ordering structure. The formation of single phases is correlated to
+Goldschmidt's tolerance factor, while the formation of the ordering structure
+is mainly correlated to cation-valence difference. We anticipate that this
+strategy is applicable to exploring HEOs in other systems.",2006.03834v1
+2020-06-16,Classical and semiclassical description of Rydberg excitons in cuprous oxide,"Experimental and theoretical investigations of excitons in cuprous oxide have
+revealed a significant fine-structure splitting of the excitonic Rydberg states
+caused by a strong impact of the valence band structure. We provide a
+semiclassical interpretation of that splitting by investigating the classical
+dynamics of the excitonic electron-hole pair beyond the hydrogen-like model.
+Considering the slow motion of Rydberg excitons in coordinate space compared to
+the fast dynamics of quasispin and hole spin we use an adiabatic approach and
+energy surfaces in momentum space for the computation of the exciton dynamics.
+We observe quasi-periodic motion on near-integrable tori. Semiclassical torus
+quantization yields the energy regions of the fine-structure splitting of
+$n$-manifolds in agreement with quantum mechanical computations.",2006.08955v1
+2020-06-29,Radio frequency field-induced electron mobility in an ultracold plasma state of arrested relaxation,"Penning ionization releases electrons in a state-selected Rydberg gas of
+nitric oxide entrained in a supersonic molecular beam. Subsequent processes of
+electron impact avalanche, bifurcation, and quench form a strongly coupled,
+spatially correlated ultracold plasma of NO$^+$ ions and electrons that
+exhibits characteristics of self-organized criticality. This plasma contains a
+residue of nitric oxide Rydberg molecules. A conventional fluid dynamics of
+ion-electron-Rydberg quasi-equilibrium predicts rapid decay to neutral atoms.
+Instead, the NO plasma endures for a millisecond or more, suggesting that
+quenched disorder creates a state of suppressed electron mobility. Supporting
+this proposition, a 60 MHz radiofrequency field with a peak-to-peak amplitude
+less than 1 V cm$^{-1}$ acts dramatically to mobilize electrons, causing the
+plasma to dissipate by dissociative recombination and Rydberg predissociation.
+An evident density dependence shows that this effect relies on collisions,
+giving weight to the idea of arrested relaxation as a cooperative property of
+the ensemble.",2006.16412v2
+2020-08-06,Promising photovoltaic efficiency of a layered silicon oxide crystal Si$_{3}$O,"Computational searching and screening of new functional materials exploiting
+earth abundant elements can accelerate developments of their energy
+applications. Based on a state-of-the-art materials search algorithm and ab
+initio calculations, we demonstrate a recently suggested stable silicon oxide
+with a layered structure (Si$_{3}$O) as an ideal photovoltaic material. With
+many-body first-principles approaches, the monolayer and layered bulk of
+Si$_{3}$O show direct quasiparticle gaps of 1.85 eV and 1.25 eV, respectively,
+while an optical gap of about 1.2 eV is nearly independent of the number of
+layers. Spectroscopic limited maximum efficiency (SLME) is estimated to be 27%
+for a thickness of 0.5 {\mu}m, making it a promising candidate for solar energy
+applications.",2008.02654v1
+2020-08-05,Part2: Ultra-short pulse laser patterning of very thin indium tin oxide on glass substrates,"We investigate selective patterning of ultra-thin 20 nm Indium Tin Oxide
+(ITO) thin films on glass substrates, using 343, 515, and 1030 nm femtosecond
+(fs), and 1030 nm picoseconds (ps) laser pulses. An ablative removal mechanism
+is observed for all wavelengths at both femtosecond and picoseconds
+time-scales. The absorbed threshold fluence values were determined to be 12.5
+mJ/cm2 at 343 nm, 9.68 mJ/cm2 at 515 nm, and 7.50 mJ/cm2 at 1030 nm for
+femtosecond and 9.14 mJ/cm2 at 1030 nm for picosecond laser exposure. Surface
+analysis of ablated craters using atomic force microscopy confirms that the
+selective removal of the film from the glass substrate is dependent on the
+applied fluence. Film removal is shown to be primarily through ultrafast
+lattice deformation generated by an electron blast force. The laser absorption
+and heating process was simulated using a two temperature model (TTM). The
+predicted surface temperatures confirm that film removal below 1 J/cm2 to be
+predominately by a non-thermal mechanism.",2008.05294v1
+2020-08-19,Deep-ultraviolet Layered Oxide B2S2O9 with Strong and Robust Second Harmonic Generation,"Two-dimensional (2D) layered semiconductors with both ultrawide bandgap and
+strong second harmonic generation (SHG) are essential for expanding the
+nonlinear optical (NLO) applications to deep-ultraviolet (DUV) region in
+nanoscale. Unfortunately, these materials are rare in nature and have not been
+discovered until now. In this Letter, we predict the B2S2O9 (BSO), an existing
+layered oxide, can exhibit both DUV bandgap and strong SHG effects, comparable
+to the best known DUV NLO bulks. The strong SHG intensities in BSO, originated
+from the ordered arrangement of polar SO4 and BO4 tetrahedra forming planar
+structure, are linearly tunable by the layer thickness. Surprisingly, the
+spontaneous rotations of rigid tetrahedra under strains can induce the (nearly)
+zero Poisson's ratios in BSO, which simultaneously result in the robust SHG
+effects against large strains, fundamentally differing from other known 2D NLO
+semiconductors. The discovery of BSO may provide an unprecedented opportunity
+to explore DUV NLO physics and applications in 2D limit.",2008.08309v2
+2020-08-24,One-Dimensional Twisted and Tubular Structures of Zinc Oxide by Semiconductor-Catalyzed Vapor-Liquid-Solid Synthesis,"The exploration of new catalysts for the vapor-liquid-solid (VLS) synthesis
+of one-dimensional (1-D) materials promises to yield new morphologies and
+functionality. Here, we show, for the model ZnO system, that this possible
+using a semiconductor (Ge) catalyst. In particular, two unusual morphologies
+are described: twisted nanowires and twisted nanotubes, in addition to the
+usual straight nanowires. The twisted nanotubes show large hollow cores and
+surprisingly high twisting rates (up to 9o/{\mu}m), which cannot be easily
+explained through the Eshelby twist model. A combination of ex situ and in situ
+transmission electron microscopy measurements suggest that the hollow core
+results from a competition between growth and etching at the Ge-ZnO interface
+during synthesis. The twisting rate is consistent with a softening of elastic
+rigidity. These results indicate that the use of unconventional, nonmetallic
+catalysts provide opportunities to synthesize unusual oxide structures with
+potentially useful properties.",2008.10137v1
+2020-08-26,Charge pumping under spin resonance in Si(100) metal-oxide-semiconductor transistors,"Gate-pulse-induced recombination, known as the charge pumping (CP), is a
+fundamental carrier recombination process, and has been utilized as a method
+for analyzing electrical properties of defects (or dangling bonds) at the
+transistor interfaces, which is now recognized to be well-matured and
+conventional. Nevertheless, neither the origin (the bonding configuration) of
+the defects responsible for the CP, nor their detailed recombination sequence
+has been clarified yet for Si metal-oxide-semiconductor (MOS) interfaces. In
+order to address these problems, we investigated the CP under spin resonance
+conditions at temperatures ranging from 27 to 300 K in Si(100) n-type MOS
+transistors. We obtained evidence that Pb0 and E' centers, the two major
+dangling bonds at (and near) the Si(100) interface, participate in the CP
+recombination process. We also show that the spin-dependent CP process is
+explained by the formation of electron-electron spin pairs, which in turn
+reveals that the CP via Pb0 and E' centers is inherently a two-electron
+process.",2008.11857v1
+2020-08-28,Two-beam coupling by a hot electron nonlinearity,"Transparent conductive oxides such as indium tin oxide (ITO) bear the
+potential to deliver efficient all-optical functionality due to their
+record-breaking optical nonlinearity at epsilon near zero (ENZ) wavelengths.
+All-optical applications generally involve more than one beam, but the coherent
+interaction between beams has not previously been discussed in materials with a
+hot electron nonlinearity. Here we study the optical nonlinearity at ENZ in ITO
+and show that spatial and temporal interference has important consequences in a
+two beam geometry. Our pump-probe results reveal a polarization-dependent
+transient that is explained by momentary diffraction of pump light into the
+probe direction by a temperature grating produced by pump-probe interference.
+We further show that this effect allows tailoring the nonlinearity by tuning
+frequency or chirp. Having fine control over the strong and ultrafast ENZ
+nonlinearity may enable applications in all-optical neural networks,
+nanophotonics, and spectroscopy.",2008.12824v1
+2020-09-04,Effective Thermal Conductivity of SrBi$_4$Ti$_4$O$_{15}$-La$_{0.7}$Sr$_{0.3}$MnO$_3$ Oxide composite: Role of Particle Size and Interface Thermal Resistance,"We present a novel approach to reduce the thermal conductivity ($\kappa$) in
+thermoelectric composite materials using acoustic impedance mismatch and the
+Debye model. Also, the correlation between interface thermal resistance
+(R$_{int}$) and the particle size of the dispersed phase on the k of the
+composite is discussed. In particular, the $\kappa$ of an oxide composite which
+consists of a natural superlattice Aurivillius phase (SrBi$_4$Ti$_4$O$_{15}$)
+as a matrix and perovskite (La$_{0.7}$Sr$_{0.3}$MnO$_3$) as a dispersed phase
+is investigated. A significant reduction in the $\kappa$ of composite, even
+lower than the $\kappa$ of the matrix when the particle size of
+La$_{0.7}$Sr$_{0.3}$MnO$_3$ is smaller than the Kapitza radius (a$_K$) is
+observed, depicting that R$_{int}$ dominates for particle size lower than a$_K$
+due to increased surface to volume ratio. The obtained results have the
+potential to provide new directions for engineering composite thermoelectric
+systems with desired thermal conductivity and promising in the field of energy
+harvesting.",2009.02218v1
+2020-09-07,Strain game revisited for complex oxide thin-films: Substrate-film thermal expansion mismatch in PbTiO$_3$,"The sensitivity of materials properties, particularly those of perovskite
+oxides, to epitaxial strain has been exploited to great advantage to create
+materials with new or enhanced properties. Although it has certainly been
+recognized that mismatch in the thermal expansion coefficients of the bulk and
+substrate material will contribute to the misfit strain, the significance of
+this contribution for ferroelectric perovskite thin-films has not been
+systematically explored. We use first-principles density functional theory and
+the example of ferroelectric PbTiO$_3$ thin-films on various substrates to show
+that ignoring the thermal expansion of the substrate (that is, assuming that
+the in-plane lattice parameter of the film remains roughly constant as a
+function of temperature) results in ferroelectric transition temperatures and
+structural trends that are completely qualitatively different from calculations
+in which thermal expansion mismatch is properly taken into account. Our work
+suggests that the concept of a misfit strain defined as a single number is
+particularly ill-defined for PbTiO$_3$ and invites further study of the
+interplay between thermal expansion mismatch and structural and functional
+properties in other thin-film materials.",2009.03396v1
+2020-09-14,Investigation of the Impact of Cold Plasma Treatment on the Wettability of Medical Grade Polyvinylchloride,"The impact of the Corona, dielectric barrier discharge and low pressure
+radiofrequency air plasmas on the wettability of the medical grade
+polyvinylchloride was investigated. Corona plasma treatment exerted the most
+pronounced increase in the hydrophilization of polyvinylchloride. The specific
+energy of adhesion of the pristine and plasma treated PVC tubing is reported.
+The kinetics of hydrophobic recovery following the plasma treatment was
+explored. The time evolution of the apparent contact angle under the
+hydrophobic recovery is satisfactorily described by the exponential fitting.
+Energy-dispersive X-ray spectroscopy of the chemical composition of the
+near-surface layers of the plasma treated catheters revealed their oxidation.
+The effect of the hydrophobic recovery is hardly correlated with oxidation of
+the polymer surface, which is irreversible.",2009.07102v1
+2020-09-19,Coherent transfer matrix analysis of the transmission spectra of Rydberg excitons in Cuprous Oxide,"In this study we analyze the transmission spectrum of a thin plate of Cuprous
+Oxide in the range of the absorption of the yellow exciton states with the
+coherent transfer matrix method. We demonstrate that, in contrast to the usual
+analysis using Beer's law, which turns out to be a rather good approximation
+only in the spectral region of high principal quantum numbers, a consistent
+quantitative description over the whole spectral range under consideration is
+possible. This leads to new and more accurate parameters not only for the
+Rydberg exciton states, but also for the strengths of indirect transitions.
+Furthermore, the results have consequences on the determination of the density
+of electron-hole pairs after optical excitation.",2009.09214v1
+2020-09-25,Controlling the macroscopic electrical properties of reduced graphene oxide by nanoscale writing of electronic channels,"The allure of all carbon electronics stems from the spread in physical
+properties, across all its allotropes. The scheme also harbours unique
+challenges, like tunability of band-gap, variability of doping and defect
+control. Here, we explore the technique of scanning probe tip induced nanoscale
+reduction of graphene oxide (GO), which nucleates conducting, sp2 rich
+graphitic regions on the insulating GO background. Flexibility of direct
+writing is supplemented with control over degree of reduction and tunability of
+bandgap, through macroscopic control parameters. The fabricated reduced - GO
+channels and ensuing devices are investigated via spectroscopic, and
+temperature and bias dependent electrical transport and correlated with
+spatially resolved electronic properties, using surface potentiometry. Presence
+of carrier localization effects, induced by the phase-separated sp2/sp3
+domains, and large local electric field fluctuations are reflected in the
+non-linear transport across the channels. Together the results indicate a
+complex transport phenomena which may be variously dominated by tunnelling,
+variable range hopping or activated depending on the electronic state of the
+material.",2009.12366v1
+2020-09-29,Nb Implanted BaO as a Support for Gold Single Atoms,"Using first-principles modelling based on density functional theory we show
+that oxides implanted with transition metal can act as support for Au single
+atoms, which are stable against agglomeration. In our previous work we have
+shown that implanted transition metal, doped in BaO is stable as interstitial
+in various charge states by transferring the excess charge to an acceptor level
+close to VBM. Taking Nb as an example we show that single atom Au has its Fermi
+level close to the VBM of BaO and hence is able to accept charge from the
+dopant. This charge transfer process between Nb and Au helps Au atoms bind
+strongly on the doped BaO support. We also show that these charged Au atoms
+repel each other and prefer to remain atomically dispersed preventing cluster
+formation. Substitutional doping of transition metals have earlier been
+reported to bind Au atoms. However, if doped at interstitial sites, they can
+bind more Au atoms; for example, 5 Au atoms can be anchored per Nb dopant
+present in BaO interstitial, compared to 3 Au atoms when Nb is doped at
+substitutional site. This work paves the way for an altogether new technique of
+stabilizing noble metal single atoms on transition metal doped oxides.",2009.14256v1
+2020-10-04,$Mg_xZn_{1-x}O$ contact to $CuGa_3Se_5$ absorber for photovoltaic and photoelectrochemical devices,"$CuGa_3Se_5$ is a promising candidate material with wide band gap for top
+cells in tandem photovoltaic (PV) and photoelectrochemical (PEC) devices.
+However, traditional CdS contact layers used with other chalcopyrite absorbers
+are not suitable for $CuGa_3Se_5$ due to the higher position of its conduction
+band minimum. $Mg_xZn_{1-x}O$ is a transparent oxide with adjustable band gap
+and conduction band position as a function of magnesium composition, but its
+direct application is hindered by $CuGa_3Se_5$ surface oxidation. Here,
+$Mg_xZn_{1-x}O$ is investigated as a contact (n-type buffer or window) material
+to $CuGa_3Se_5$ absorbers pretreated in $Cd^{2+}$ solution, and an onset
+potential close to 1 V vs RHE in 10 mM hexaammineruthenium (III) chloride
+electrolyte is demonstrated. The $Cd^{2+}$ surface treatment changes the
+chemical composition and electronic structure of the $CuGa_3Se_5$ surface, as
+demonstrated by photoelectron spectroscopy measurements. The performance of
+$CuGa_3Se_5$ absorber with $Cd^{2+}$ treated surface in the solid-state test
+structure depends on the Zn/Mg ratio in the $Mg_xZn_{1-x}O$ layer. The measured
+open circuit voltage close to 1 V is promising for tandem PEC water splitting
+with $CuGa_3Se_5$/$Mg_xZn_{1-x}O$ top cells.",2010.01635v1
+2020-10-06,New insights into the mechanism of graphene oxide and radionuclide interaction through vacancy defects,"The sorption of radionuclides by graphene oxides synthesized by different
+methods was studied through a combination of batch experiments with
+characterization by microscopic and spectroscopic techniques such as X-ray
+photoelectron spectroscopy (XPS), attenuated total reflection fourier-transform
+infrared spectroscopy (ATR-FTIR), high-energy resolution fluorescence detected
+X-Ray absorption spectroscopy (HERFD-XANES), extended X-ray absorption fine
+structure (EXAFS) and high resolution transmission electron microscopy (HRTEM).",2010.02965v1
+2020-10-07,Modeling of Nuclear Waste Forms: State-of-the-Art and Perspectives,"Computational modeling is an important aspect of the research on nuclear
+waste materials. In particular, atomistic simulations, when used complementary
+to experimental efforts, contribute to the scientific basis of safety case for
+nuclear waste repositories. Here we discuss the state-of-the-art and
+perspectives of atomistic modeling for nuclear waste management on a few cases
+of successful synergy of atomistic simulations and experiments. In particular,
+we discuss here: (1) the potential of atomistic simulations to investigate the
+uranium oxidation state in mixed valence uranium oxides and (2) the ability of
+cementitious barrier materials to retain radionuclides such as 226Ra and 90Sr,
+and of studtite/metastudtite secondary peroxide phases to incorporate actinides
+such as Np and Am. The new contribution we make here is the computation of the
+incorporation of Sr by C-S-H (calcium silicate hydrate) phases.",2010.03270v1
+2020-10-08,Structural evolution of binary oxide nanolaminates with annealing and its impact on room-temperature internal friction,"Internal friction in oxide thin films imposes a critical limitation to the
+sensitivity and stability of ultra-high finesse optical cavities for
+gravitational wave detectors. Strategies like doping or creating nanolaminates
+are sought to introduce structural modifications that reduce internal friction.
+This work describes an investigation of the morphological changes SiO2/Ta2O5
+and TiO2/Ta2O5 nanolaminates undergo with annealing and their impact on room
+temperature internal friction. It is demonstrated that thermal treatment
+results in a reduction of internal friction in both nanolaminates, but through
+different pathways. In the SiO2/Ta2O5 nanolaminate, which layers remain intact
+after annealing, the total reduction in internal friction follows the reduction
+in the composing SiO2 and Ta2O5 layers. Instead, interdiffusion initiated by
+annealing at the interface of the TiO2/Ta2O5 nanolaminate and the formation of
+a mixed phase dictate a more significant reduction in internal friction to ~
+2.6 * 10-4, a value lower than any other Ta2O5 mixture coating with similar
+cation concentration.",2010.04272v1
+2020-10-16,An upgraded ultra-high vacuum magnetron-sputtering system for high-versatility and software-controlled deposition,"Magnetron sputtering is a widely used physical vapor deposition technique.
+Reactive sputtering is used for the deposition of, e.g, oxides, nitrides and
+carbides. In fundamental research, versatility is essential when designing or
+upgrading a deposition chamber. Furthermore, automated deposition systems are
+the norm in industrial production, but relatively uncommon in laboratory-scale
+systems used primarily for fundamental research. Combining automatization and
+computerized control with the required versatility for fundamental research
+constitutes a challenge in designing, developing, and upgrading laboratory
+deposition systems. The present article provides a detailed description of the
+design of a lab-scale deposition chamber for magnetron sputtering used for the
+deposition of metallic, oxide, nitride and oxynitride films with automated
+controls, dc or pulsed bias, and combined with a coil to enhance the plasma
+density near the substrate. LabVIEW software (provided as Supplementary
+Information) has been developed for a high degree of computerized or automated
+control of hardware and processes control and logging of process details.",2010.08411v2
+2020-10-22,Electrical and Thermal Transport Properties of the beta-Pyrochlore Oxide CsW2O6,"We report the electrical resistivity, thermoelectric power, and thermal
+conductivity of single-crystalline and sintered samples of the 5d pyrochlore
+oxide CsW2O6. The electrical resistivity of the single crystal is 3 mohm cm at
+295 K and gradually increases with decreasing temperature above 215 K (Phase
+I). The thermoelectric power of the single-crystalline and sintered samples
+shows a constant value of approximately -60 uV K-1 in Phase I. These results
+reflect that the electron conduction by W 5d electrons in Phase I is incoherent
+and in the hopping regime, although a band gap does not open at the Fermi
+level. The thermal conductivity in Phase I of both samples is considerably low,
+which might be due to the rattling of Cs+ ions. In Phase II below 215 K, the
+electrical resistivity and the absolute value of thermoelectric power of both
+samples strongly increase with decreasing temperature, corresponding to a
+transition to a semiconducting state with a band gap open at the Fermi level,
+while the thermal conductivity in Phase II is smaller than that in Phase I.",2010.11404v1
+2020-10-27,Particle size effect on the Langmuir-Hinshelwood barrier for CO oxidation on regular arrays of Pd clusters supported on ultrathin alumina films,"The Langmuir-Hinshelwood barrier (ELH) and the pre-exponential factor
+($\nu$LH) for CO oxidation have been measured at high temperature on hexagonal
+arrays of Pd clusters supported on an ultrathin alumina film on Ni3Al(111). The
+Pd clusters have a sharp size distribution and the mean sizes are: 174$\pm$13,
+360$\pm$19 and 768$\pm$28 atoms. ELH and $\nu$LH are determined from the
+initial reaction rate of a CO molecular beam with a saturation layer of
+adsorbed oxygen on the Pd clusters, measured at different temperatures
+(493$\le$T (K) $\le$613). The largest particles (3.5 nm) give values of ELH and
+$\nu$LH similar to those measured on Pd (111) [2]. However, smaller particles
+(2.7 and 2.1 nm) show very different behavior. The origin of this size effect
+is discussed in terms of variation of the electronic structure and of the
+atomic structure of the Pd clusters.",2010.14147v1
+2020-10-28,A periodic equation-of-motion coupled-cluster implementation applied to $F$-centers in alkaline earth oxides,"We present an implementation of equation of motion coupled-cluster singles
+and doubles (EOM-CCSD) theory using periodic boundary conditions and a plane
+wave basis set. Our implementation of EOM-CCSD theory is applied to study
+$F$-centers in alkaline earth oxides employing a periodic supercell approach.
+The convergence of calculated electronic excitation energies for neutral color
+centers in MgO, CaO and SrO crystals with respect to orbital basis set and
+system size is explored. We discuss extrapolation techniques that approximate
+excitation energies in the complete basis set limit and reduce finite size
+errors. Our findings demonstrate that EOM-CCSD theory can predict optical
+absorption energies of $F$-centers in good agreement with experiment.
+Furthermore, we discuss calculated emission energies corresponding to the decay
+from triplet to singlet states, responsible for the photoluminescence
+properties. Our findings are compared to experimental and theoretical results
+available in literature.",2010.15071v1
+2020-10-29,Asymmetric Rydberg blockade of giant excitons in Cuprous Oxide,"The ability to generate and control strong long-range interactions via highly
+excited electronic states has been the foundation for recent breakthroughs in a
+host of areas, from atomic and molecular physics [1, 2] to quantum optics [3,
+4] and technology [5-7]. Rydberg excitons provide a promising solid-state
+realization of such highly excited states, for which record-breaking orbital
+sizes of up to a micrometer have indeed been observed in cuprous oxide
+semiconductors [8]. Here, we demonstrate the generation and control of strong
+exciton interactions in this material by optically producing two distinct
+quantum states of Rydberg excitons. This makes two-color pump-probe experiments
+possible that allow for a detailed probing of the interactions. Our experiments
+reveal the emergence of strong spatial correlations and an inter-state Rydberg
+blockade that extends over remarkably large distances of several micrometers.
+The generated many-body states of semiconductor excitons exhibit universal
+properties that only depend on the shape of the interaction potential and yield
+clear evidence for its vastly extended-range and power-law character.",2010.15459v1
+2020-11-01,Light induced resistive switching in copper oxide thin films,"Copper oxide thin film based metal-insulator-metal structures were subjected
+to white light irradiation.The top electrodes included Al, Cr and Ni while the
+bottom electrode was either Au or Pt. A white light pulse controls the set
+process and this light induced set (LIS) can be performed at very low voltages
+(tens of milli volts) which is not possible in the normal set process. The LIS
+is initiated at the positive edge of the pulse and there is no effect of the
+falling edge of the light. In most cases the high resistance state (HRS) to low
+resistance state (LRS) transition is irreversible i.e.the devices continue to
+remain in the LRS even after the light pulse is switched off. Light induced
+reset (LIR) is achieved in only one device structure Al/CuxO/Au. By using LIS
+and LIR, set and reset power of the device can be reduced to a great extent and
+the set and reset parameters variation also reduces. The current work, thus,
+points to the possibility of formation and compliance-free resistive random
+access memory devices.",2011.00423v1
+2020-11-08,Studies on optical signal due to oxygen effect on hydrogenated amorphous/crystalline silicon thin-films,"We have studied the effects of oxygen on hydrogenated amorphous/crystalline
+silicon films in terms of their structural and optical properties. Different
+hydrogenated silicon oxide (SiO:H) and silicon (Si:H) films are fabricated
+between microcrystalline and amorphous transition region. X-ray diffraction,
+Raman, FTIR and UV-Vis emission spectrometry have been used to characterize
+different films. A comparison of the results with those of different types of
+films like hydrogenated amorphous silicon oxide (a-SiO:H), hydrogenated
+amorphous silicon (a-Si:H) and microcrystalline silicon ($\mu$c-Si:H) films
+reveal their superiority as an excellent substance for solar cell. X-ray
+diffraction, FTIR and Raman spectral analysis show that difference of the H
+dilution effect has a major effect on the structure of the film and the optical
+properties. Photoluminescence analysis of amorphous silicon-oxygen and
+silicon-hydride alloy films has established their efficient application
+appropriate as Si based light emitting devices. A large optical band gap of
+1.83 eV and appearance of strong photo luminescence at 2.0 eV validates the
+applicability of a-SiO:H film as a better alternative for the solar cells.",2011.03930v1
+2020-11-08,Molecular dynamics simulations of sodium nanoparticle deposition on magnesium oxide,"The interaction of mass-selected atomic clusters and nanoparticles with
+surfaces attracts strong interest in view of fundamental research and
+technological applications. Understanding dynamics of the deposition process is
+important for controlling structure and functioning of deposited nanoparticles
+on a substrate, but experimental techniques can usually observe only the final
+outcome of the deposition process. In this paper, the deposition of 4 nm-sized
+sodium nanoparticles on an experimentally relevant magnesium oxide substrate is
+studied by means of classical molecular dynamics simulations. An empirical
+force field is derived which accounts for the interaction of highly polarizable
+Na atoms with the surface, reproducing the results of previously reported
+quantum mechanics/molecular mechanics simulations. Molecular dynamics
+simulations permit exploring the dynamics of deposited nanoparticles on long
+timescales on the order of hundreds of picoseconds, thus enabling the analysis
+of energy relaxation mechanisms and the evolution of nanoparticle structure up
+to its thermalization with the substrate. Several nanoparticle characteristics,
+such as internal structure, contact angle, and aspect ratio are studied in a
+broad deposition energy range from the soft landing to multi-fragmentation
+regimes.",2011.04024v1
+2020-11-17,Observation of two-dimensional superconductivity at the LaAlO3/KTaO3(110) heterointerface,"We report on the observation of a Tc ~0.9 K superconductivity at the
+interface between LaAlO3 film and the 5d transition-metal oxide KTaO3(110)
+single crystal. The interface shows a large anisotropy of the upper critical
+field, and its superconducting transition is consistent with a
+Berezinskii-Kosterlitz-Thouless transition. Both facts suggest that the
+superconductivity is two-dimensional (2D) in nature. The carrier density
+measured at 5 K is ~7 time 10^13 cm-2. The superconducting layer thickness and
+coherence length are estimated to be ~8 and ~30 nm, respectively. Our result
+provides a new platform for the study of 2D superconductivity at oxide
+interfaces.",2011.08526v1
+2020-11-18,Crystal structure built from a GeO$_6$-GeO$_5$ polyhedra network with high thermal stability: $β$-SrGe$_2$O$_5$,"By tackling the challenge of extending transparent oxide semiconductors to Ge
+based oxides, we have found a not-yet-reported crystal structure, named
+$\beta$-SrGe$_2$O$_5$, which is composed of edge-sharing GeO$_6$ octahedra
+interconnected by GeO$_5$ bipyramids. Single crystals were successfully grown
+by the high-pressure flux method. $\beta$-SrGe$_2$O$_5$ has a band gap of 5.2
+eV and a dispersive conduction band with an effective mass as small as 0.34
+times the electron rest mass, which originates from the edge-sharing GeO$_6$
+octahedra network. Although known compounds with octahedral GeO$_6$
+coordination are commonly unstable at atmospheric pressure and elevated
+temperatures, $\beta$-SrGe$_2$O$_5$ exhibits thermal stability up to 700
+$^\circ$C.",2011.09443v1
+2021-02-01,Predicting nanocrystal morphology governed by interfacial strain,"The shape dependence for the technologically important nickel oxide (NiO)
+nanocrystals on (001) strontium titanate substrates is investigated under the
+generalized Wulff-Kaichew (GWK) theorem framework. It is found that the shape
+of the NiO nanocrystals is primarily governed by the existence (or absence) of
+interfacial strain. Nanocrystals that have a fully pseudomorphic interface with
+the substrate (i.e. the epitaxial strain is not relaxed) form an embedded
+smooth ball-crown morphology with {001}, {011}, {111} and high-index {113}
+exposed facets with a negative Wulff point. On the other hand, when the
+interfacial strain is relaxed by misfit dislocations, the nanocrystals take on
+a truncated pyramidal shape, bounded by {111} faces and a {001} flat top, with
+a positive Wulff point. Our quantitative model is able to predict both
+experimentally observed shapes and sizes with good accuracy. Given the
+increasing demand for hetero-epitaxial nanocrystals in various physio-chemical
+and electro-chemical functional devices, these results lay the important
+groundwork in exploiting the GWK theorem as a general analytical approach to
+explain hetero-epitaxial nanocrystal growth on oxide substrates governed by
+interface strain.",2102.01220v1
+2021-02-03,Band structure of tungsten oxide W$_{20}$O$_{58}$ with ideal octahedra,"The band structure, density of states, and the Fermi surface of a tungsten
+oxide WO$_{2.9}$ with idealized crystal structure (ideal octahedra WO$_6$
+creating a ""square lattice"") is obtained within the density functional theory
+in the generalized gradient approximation. Because of the oxygen vacancies
+ordering this system is equivalent to the compound W$_{20}$O$_{58}$
+(Magn\'{e}li phase), which has 78 atoms in unit cell. We show that
+5$d$-orbitals of tungsten atoms located immediately around the voids in the
+zigzag chains of edge-sharing octahedra give the dominant contribution near the
+Fermi level. These particular tungsten atoms are responsible of a low-energy
+properties of the system.",2102.01983v2
+2021-02-09,The role of heat generation and fluid flow in plasmon-enhanced reduction-oxidation reactions,"Recently, we have shown that thermal effects play a crucial role in speeding
+up the rate of bond-dissociation reactions. This was done by applying a simple
+temperature-shifted Arrhenius Law to the experimental data, corroborated with
+detailed account of the heat diffusion occurring within the relevant samples
+and identification of errors in the temperature measurements. Here, we provide
+three important extensions of our previous studies. First, we analyze thermal
+effects in reduction-oxidation (redox) reactions, where charge transfer is an
+integral part of the reaction. Second, we analyze not only the spatial
+distribution of the temperature, but also its temporal dynamics. Third, we also
+model the fluid convection and stirring. An analysis of two exemplary
+experimental studies allows us to show that thermal effects can explain the
+experimental data in one of experiments (Baumberg and coworkers), but not in
+the other (Jain and coworkers), showing that redox reactions are not
+necessarily driven by non-thermal charge carriers.",2102.04783v1
+2021-02-14,Graphene oxide films for ultra-flat optics and linear and nonlinear integrated photonic circuits,"With superior optical properties, high flexibility in engineering its
+material properties, and strong capability for large-scale on-chip integration,
+graphene oxide (GO) is an attractive solution for on-chip integration of
+two-dimensional (2D) materials to implement functional integrated photonic
+devices capable of new features. Over the past decade, integrated GO photonics,
+representing an innovative merging of integrated photonic devices and thin GO
+films, has experienced significant development, leading to a surge in many
+applications covering almost every field of optical sciences. This paper
+reviews the recent advances in this emerging field, providing an overview of
+the optical properties of GO as well as methods for the on-chip integration of
+GO. The main achievements made in GO hybrid integrated photonic devices for
+diverse applications are summarized. The open challenges as well as the
+potential for future improvement are also discussed.",2102.07251v1
+2021-02-15,Data-driven analysis of the electronic-structure factors controlling the work functions of perovskite oxides,"Tuning the work functions of materials is of practical interest for
+maximizing the performance of microelectronic and (photo)electrochemical
+devices, as the efficiency of these systems depends on the ability to control
+electronic levels at surfaces and across interfaces. Perovskites are promising
+compounds to achieve such control. In this work, we examine the work functions
+of more than 1,000 perovskite oxide surfaces (ABO$_3$) by data-driven
+(machine-learning) analysis and identify the factors that determine their
+magnitude. While the work functions of BO$_2$-terminated surfaces are sensitive
+to the energy of the hybridized oxygen p bands, the work functions of
+AO-terminated surfaces exhibit a much less trivial dependence with respect to
+the filling of the d bands of the B-site atom and of its electronic affinity.
+This study shows the utility of interpretable data-driven models in analyzing
+the work functions of cubic perovskites from a limited number of
+electronic-structure descriptors.",2102.07320v1
+2021-02-17,Exchange interaction in the yellow exciton series of cuprous oxide,"We experimentally and numerically investigate the exchange interaction of the
+yellow excitons in cuprous oxide. By varying the material parameters in the
+numerical calculations, we can interpret experimental findings and understand
+their origin in the complex band structure and central-cell corrections. In
+particular, we experimentally observe the reversal of the ortho- and
+paraexciton for the $2S$ yellow exciton, and explain this phenomenon by an
+avoided crossing with the green $1S$ orthoexciton in a detailed numerical
+analysis. Furthermore, we discuss the exchange splitting as a function of the
+principal quantum number $n$ and its deviation from the $n^{-3}$ behavior
+expected from a hydrogenlike model. We also explain why the observed exchange
+splitting of the green $1S$ exciton is more than twice the splitting of the
+yellow $1S$ state.",2102.08900v1
+2021-02-23,Predicting the pseudocapacitive windows for MXene electrodes with voltage-dependent cluster expansion models,"MXene transition-metal carbides and nitrides are of growing interest for
+energy storage applications. These compounds are especially promising for use
+as pseudocapacitive electrodes due to their ability to convert energy
+electrochemically at fast rates. Using voltage-dependent cluster expansion
+models, we predict the charge storage performance of MXene pseudocapacitors for
+a range of electrode compositions. $M_3C_2O_2$ electrodes based on group-VI
+transition metals have up to 80% larger areal energy densities than
+prototypical titanium-based ( e.g. $Ti_3C_2O_2$) MXene electrodes. We attribute
+this high pseudocapacitance to the Faradaic voltage windows of group-VI MXene
+electrodes, which are predicted to be 1.2 to 1.8 times larger than those of
+titanium-based MXenes. The size of the pseudocapacitive voltage window
+increases with the range of oxidation states that is accessible to the MXene
+transition metals. By similar mechanisms, the presence of multiple ions in the
+solvent (Li$^+$ and H$^+$) leads to sharp changes in the transition-metal
+oxidation states and can significantly increase the charge capacity of MXene
+pseudocapacitors.",2102.11863v1
+2021-02-26,Crossover from itinerant to localized states in the thermoelectric oxide [Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$],"The layered cobaltite [Ca$_2$CoO$_3$]$_{0.62}$[CoO$_2$], often expressed as
+the approximate formula Ca$_3$Co$_4$O$_9$, is a promising candidate for
+efficient oxide thermoelectrics but an origin of its unusual thermoelectric
+transport is still in debate. Here we investigate \textit{in-plane} anisotropy
+of the transport properties in a broad temperature range to examine the
+detailed conduction mechanism. The in-plane anisotropy between $a$ and $b$ axes
+is clearly observed both in the resistivity and the thermopower, which is
+qualitatively understood with a simple band structure of the triangular lattice
+of Co ions derived from the angle-resolved photoemission spectroscopy
+experiments. On the other hand, at high temperatures, the anisotropy becomes
+smaller and the resistivity shows a temperature-independent behavior, both of
+which indicate a hopping conduction of localized carriers. Thus the present
+observations reveal a crossover from low-temperature itinerant to
+high-temperature localized states, signifying both characters for the enhanced
+thermopower.",2102.13250v1
+2021-02-26,Catalytic effect of plasma in lowering the reduction temperature of $Fe_{2}O_{3}$,"Atmospheric pressure plasma (APP) generates highly reactive species that are
+useful for surface activations. We demonstrate a fast regeneration of iron
+oxides, that are popular catalysts in various industrial processes, using
+microwave-driven argon APP under ambient condition. The surface treatment of
+hematite powder by the APP with a small portion of hydrogen (0.5%) lowers the
+oxide's reduction temperature. A near-infrared laser is used for localized
+heating to control the surface temperature. Controlled experiments without
+plasma confirm the catalytic effect of the plasma. Raman, XRD, SEM, and XPS
+analyses show that the plasma treatment changed the chemical state of the
+hematite to that of magnetite without sintering.",2102.13369v1
+2021-03-05,High thermoelectric power factor of poly(3-hexylthiophene) through in-plane alignment and doping with a molybdenum dithiolene complex,"Here we report a record thermoelectric power factor of up to 160 $\mu$ W m-1
+K-2 for the conjugated polymer poly(3-hexylthiophene) (P3HT). This result is
+achieved through the combination of high-temperature rubbing of thin films
+together with the use of a large molybdenum dithiolene p-dopant with a high
+electron affinity. Comparison of the UV-vis-NIR spectra of the chemically doped
+samples to electrochemically oxidized material reveals an oxidation level of
+10%, i.e. one polaron for every 10 repeat units. The high power factor arises
+due to an increase in the charge-carrier mobility and hence electrical
+conductivity along the rubbing direction. We conclude that P3HT, with its
+facile synthesis and outstanding processability, should not be ruled out as a
+potential thermoelectric material.",2103.03852v1
+2021-03-09,Anisotropy of the In-Plane and Out-of-Plane Resistivity and the Hall Effect in the Normal State of Vicinal-Grown YBa$_{2}$Cu$_{3}$O$_{7-δ}$ Thin Films,"The resistivity and the Hall effect in the copper-oxide high-temperature
+superconductor YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ (YBCO) are remarkably
+anisotropic. Using a thin film of YBCO grown on an off-axis cut SrTiO$_3$
+substrate allows one to investigate these anisotropic transport properties in a
+planar and well-defined sample geometry employing a homogeneous current
+density. In the normal state, the Hall voltage probed parallel to the
+copper-oxide layers is positive and strongly temperature dependent, whereas the
+out-of-plane Hall voltage is negative and almost temperature independent. The
+results confirm previous measurements on single crystals by an entirely
+different measurement method and demonstrate that vicinal thin films might be
+also useful for investigations of other layered nanomaterials.",2103.05511v1
+2021-03-23,Searching for refractory plasmonic materials: the structural and optical properties of Au$_{3}$Zr intermetallic thin films,"Optical properties of refractory intermetallic thin films of Au$_{3}$Zr were
+experimentally investigated for the first time, which show distinctive
+plasmonic properties in the visible and near infrared region. The films were
+fabricated through DC magnetron sputtering at various deposition temperature
+ranging from room temperature to 427$^{o}$C and annealed at different vacuum
+levels. Both the structural and optical properties are found to be critically
+dependent on deposition temperature and anneal conditions. Films deposited
+between 205-320$^{o}$C are shown to exhibit lower negative permittivity and
+better thermal stability, which could be linked to specific crystalline
+orientations. The films are stable when annealed at 10$^{-8}$ Torr, but are
+partially oxidized when annealed at 10$^{-6}$ Torr, suggesting oxidization
+could be a restricting issue for high-temperature applications in ambient
+environment.",2103.12888v1
+2021-03-24,beta-Ga2O3 Double Gate Junctionless FET with an Efficient Volume Depletion Region,"This paper presents a new \b{eta}-Ga2O3 junctionless double gate
+Metal-Oxide-Field-Semiconductor-Effect-Transistor (\b{eta}DG-JL-FET) that a P+
+packet embedded in the oxide layer (PO-\b{eta}DG-JL-FET) for high-voltage
+applications. Our goal is to achieve an efficient volume depletion region by
+placing a P+ layer of silicon. We show that the proposed structure has a
+subthreshold swing ~ 64 mV/decade and it suppressed the band to band tunneling
+(BTBT) phenomenon. Also, the PO-\b{eta}DG-JL-FET structure has a high Ion/Ioff
+~ 1.3e15. The embedded layer reduces the off-current (IOFF) by ~ 10-4, while
+the on-current (ION) reduces slightly. Besides, we show that the proposed
+structure has acceptable Ioff value in a range of gate work functions which
+help us to the optimization of designs in terms of area, power gain, and
+leakage current. The leakage current of the proposed structure is ~ 7e-17 A in
+400 K temperature. Furthermore, the fabrication process steps of the proposed
+structure will be investigated.",2103.13022v1
+2021-03-29,"Double-site Substitution of Ce into (Ba, Sr)MnO3 Perovskites for Solar Thermochemical Hydrogen Production","Solar thermochemical hydrogen production (STCH) is a renewable alternative to
+hydrogen produced using fossil fuels. While serial bulk experimental methods
+can accurately measure STCH performance, screening chemically complex materials
+systems for new promising candidates is more challenging. Here we identify
+double-site Ce-substituted (Ba,Sr)MnO3 oxide perovskites as promising STCH
+candidates using a combination of bulk synthesis and high-throughput thin film
+experiments. The Ce substitution on the B-site in 10H-BaMnO3 and on the A-site
+in 4P-SrMnO3 lead to 2-3x higher hydrogen production compared to CeO2, but
+these bulk single-site substituted perovskites suffer from incomplete
+reoxidation. Double-site Ce substitution on both A- and B-site in (Ba,Sr)MnO3
+thin films increases Ce solubility and extends the stability of 10H and 4P
+structures, which is promising for their thermochemical reversibility. This
+study demonstrates a high-throughput experimental method for screening complex
+oxide materials for STCH applications.",2103.15805v2
+2021-03-29,Photoluminescence of ion-synthesized 9R-Si inclusions in SiO2/Si structure: effect of irradiation dose and oxide film thickness,"The study of hexagonal silicon polytypes attracts special attention due to
+their unique physical properties compared to the traditional cubic phase of Si.
+Thus, for some hexagonal phases, a significant improvement in the emission
+properties has been demonstrated. In this work, the luminescent properties of
+SiO2/Si structures irradiated with Kr+ ions at different doses and annealed at
+800 {\deg}C have been systematically investigated. For such structures, a
+photoluminescence line at ~ 1240 nm is observed and associated with the
+formation of hexagonal 9R-Si phase inclusions. It is found that the variation
+in the thickness of oxide film and the relative position of ion distribution
+profile and film / substrate interface leads to a regular change in the
+luminescence intensity. The nature of the observed dependencies is discussed as
+related to the interplay between the desirable 3C-Si -> 9R-Si structural
+transition and generation of nonradiative defects. The revealed regularities
+suggest optimal ion irradiation conditions for synthesis of optically active
+9R-Si phase in diamond-like silicon.",2103.15867v1
+2021-03-29,Fluorescence intensity correlation imaging with high resolution and elemental contrast using intense x-ray pulses,"We theoretically investigate the fluorescence intensity correlation (FIC) of
+Ar clusters and Mo-doped iron oxide nanoparticles subjected to intense,
+femtosecond and sub-femtosecond XFEL pulses for high-resolution and elemental
+contrast imaging. We present the FIC of {\Ka} and {\Kah} emission in Ar
+clusters and discuss the impact of sample damage on retrieving high-resolution
+structural information and compare the obtained structural information with
+those from the coherent difractive imaging (CDI) approach. We found that, while
+sub-femtosecond pulses will substantially benefit the CDI approach,
+few-femtosecond pulses may be sufficient for achieving high-resolution
+information with FIC. Furthermore, we show that the fluorescence intensity
+correlation computed from the fluorescence of Mo atoms in Mo-doped iron oxide
+nanoparticles can be used to image dopant distributions.",2103.15872v1
+2021-03-31,An Unexpected Role of H During SiC Corrosion in Water,"During aqueous corrosion, atoms in the solid react chemically with oxygen,
+leading either to the formation of an oxide film or to the dissolution of the
+host material. Commonly, the first step in corrosion involves an oxygen atom
+from the dissociated water that reacts with the surface atoms and breaks near
+surface bonds. In contrast, hydrogen on the surface often functions as a
+passivating species. Here, we discovered that the roles of O and H are reversed
+in the early corrosion stages on a Si terminated SiC surface. O forms stable
+species on the surface, and chemical attack occurs by H that breaks the Si-C
+bonds. This so-called hydrogen scission reaction is enabled by a newly
+discovered metastable bridging hydroxyl group that can form during water
+dissociation. The Si atom that is displaced from the surface during water
+attack subsequently forms H2SiO3, which is a known precursor to the formation
+of silica and silicic acid. This study suggests that the roles of H and O in
+oxidation need to be reconsidered.",2103.16739v1
+2021-04-02,Transparent Conductive Oxides-based Architectures for the Electrical Modulation of the Optical Response: A Spectroscopic Ellipsometry Study,"Transparent Conductive Oxides (TCOs) are a class of materials that combine
+high optical transparency with high electrical conductivity. This property
+makes them uniquely appealing as transparent-conductive electrodes in solar
+cells and interesting for optoelectronics and infrared-plasmonics applications.
+One of the new challenges that researchers and engineers are facing is merging
+optical and electrical control in a single device for developing
+next-generation photovoltaic, opto-electronic devices and energyefficient
+solid-state lighting. In this work, we investigated the possible variations in
+the dielectric properties of aluminum-doped ZnO (AZO) upon gating, by means of
+Spectroscopic Ellipsometry (SE). We investigated the electrical-bias-dependent
+optical response of thin AZO films fabricated by magnetron sputtering, within a
+parallel-plane capacitor configuration. We address the possibility to control
+their optical and electric performances by applying bias, monitoring the effect
+of charge injection/depletion in the AZO layer by means of in-operando SE vs
+applied gate voltage.",2104.01147v1
+2021-04-04,Stretchable optical diffraction grating from poly(acrylic acid)/polyethylene oxide stereocomplex,"Optical gratings are a key component in many spectroscopy, communications,
+and imaging systems. While initially static elements, advances in optical
+materials have enabled dynamically tunable gratings to be designed. One common
+tuning strategy is relying on mechanical deformation of the grating pitch to
+modify the diffraction pattern. To date, most mechanically adaptive optical
+gratings consist of a hybrid system where rigid moieties are patterned on an
+elastomeric substrate. In the present work, we demonstrate an all-polymer
+tunable grating that is fabricated using replica molding from the poly(acrylic
+acid) (PAA)/polyethylene oxide (PEO) polymer stereocomplex. PAA/PEO pristine
+films exhibit excellent optical transmittance at or above 80% from 500 nm to
+1400 nm and stretchability over 800% strain. The experimental studies on the
+changes of diffraction mode distances with respect to the applied strains agree
+well with the finite-difference time-domain (FDTD) theoretical modeling.",2104.01660v2
+2021-04-06,Active learning and element embedding approach in neural networks for infinite-layer versus perovskite oxides,"Combining density functional theory simulations and active learning of neural
+networks, we explore formation energies of oxygen vacancy layers, lattice
+parameters, and their correlations in infinite-layer versus perovskite oxides
+across the periodic table, and place the superconducting nickelate and cuprate
+families in a comprehensive statistical context. We show that neural networks
+predict these observables with high precision, using only 30-50% of the data
+for training. Element embedding autonomously identifies concepts of chemical
+similarity between the individual elements in line with human knowledge. Based
+on the fundamental concepts of entropy and information, active learning
+composes the training set by an optimal strategy without a priori knowledge and
+provides systematic control over the prediction accuracy. This offers key
+ingredients to considerably accelerate scans of large parameter spaces and
+exemplifies how artificial intelligence may assist on the quantum scale in
+finding novel materials with optimized properties.",2104.02529v1
+2021-04-12,Quasiparticle interference and quantum confinement in a correlated Rashba spin-split 2D electron liquid,"Exploiting inversion symmetry breaking (ISB) in systems with strong
+spin-orbit coupling promises control of spin through electric fields - crucial
+to achieve miniaturization in spintronic devices. Delivering on this promise
+requires a two-dimensional electron gas with a spin precession length shorter
+than the spin coherence length and a large spin splitting so that spin
+manipulation can be achieved over length scales of nanometers. Recently, the
+transition metal oxide terminations of delafossite oxides were found to exhibit
+a large Rashba spin splitting dominated by ISB. In this limit, the Fermi
+surface exhibits the same spin texture as for weak ISB, but the orbital texture
+is completely different, raising questions about the effect on quasiparticle
+scattering. We demonstrate that the spin-orbital selection rules relevant for
+conventional Rashba system are obeyed as true spin selection rules in this
+correlated electron liquid and determine its spin coherence length from
+quasiparticle interference imaging.",2104.05718v1
+2021-04-14,Detailed thermal reduction analyses of Graphene Oxide via in-situ TEM/EELS studies,"We report an in-depth study of the reduction of graphene oxide (GO) by
+in-situ thermal transmission electron microscopy (TEM) analysis. In-situ
+heating high-resolution TEM (HRTEM) imaging and electron energy-loss
+spectroscopy (EELS) measurements have been combined to identify the
+transformations of different oxygen functional groups, the desorption of
+physisorbed and chemisorbed water and the graphitization as a function of the
+temperature in the range from 70 up to 1200{\deg}C. A model for the general
+removal of water and OFGs is proposed based on different chemical and physical
+parameters that have been monitored. All this unique information provides a
+detailed roadmap of the thermal behaviour of GO at an extended range of
+temperature. This is not only of interest to understand the thermal reduction
+process of GO but also of critical relevance to the response of GO in
+applications when exposed to thermal effects.",2104.06840v1
+2021-04-14,In-situ reduction by Joule heating and measurement of electrical conductivity of graphene oxide in a transmission electron microscope,"Graphene oxide (GO) is reduced by Joule heating using in-situ transmission
+electron microscopy (TEM). The approach allows the simultaneous study of GO
+conductivity by electrical measurements and of its composition and structural
+properties throughout the reduction process by TEM, electron diffraction and
+electron energy-loss spectroscopy. The small changes of GO properties observed
+at low applied electric currents are attributed to the promotion of diffusion
+processes. The actual reduction process starts from an applied power density of
+about 2 1014 Wm-3 and occurs in a highly uniform and localized manner. The
+conductivity increases more than 4 orders of magnitude reaching a value of 3
+103 Sm-1 with a final O content of less than 1%. We discuss differences between
+the reduction by thermal annealing and Joule heating.",2104.07088v1
+2021-04-25,Improved Hopfield Network Optimization using Manufacturable Three-terminal Electronic Synapses,"We describe via simulation novel optimization algorithms for a Hopfield
+neural network constructed using manufacturable three-terminal
+Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) synaptic devices. We first present
+a computationally-light, memristor-based, highly accurate compact model for the
+SONOS. Using the compact model, we describe techniques of simulated annealing
+in Hopfield networks by exploiting imperfect problem definitions, current
+leakage, and the continuous tunability of the SONOS to enable transient chaotic
+group dynamics. We project improvements in energy consumption and latency for
+optimization relative to the best CPUs and GPUs by at least 4 orders of
+magnitude, and also exceeding the best projected memristor-based hardware;
+along with a 100-fold increase in error-resilient hardware size (i.e., problem
+size).",2104.12288v1
+2021-05-01,Complementary electrochemical ICP-MS flow cell and in-situ AFM study of the anodic desorption of molecular adhesion promotors,"Molecular adhesion promoters are a central component of modern coating
+systems for the corrosion protection of structural materials. They are
+interface active and form ultrathin corrosion inhibiting and adhesion-promoting
+layers. Here we utilize thiol-based self-assembled monolayers (SAMs) as model
+system for demonstrating a comprehensive combinatorial approach to understand
+molecular level corrosion protection mechanisms under anodic polarization.
+Specifically, we compare hydrophilic 11-Mercapto-1-undecanol and hydrophobic
+1-Undecanethiol SAMs and their gold-dissolution inhibiting properties. We can
+show that the intermolecular forces (hydrophobic vs hydrophilic effects)
+control how SAM layers perform under oxidative conditions. Specifically, using
+\textit{in situ} electrochemical AFM and a scanning-flow cell coupled to an
+ICP-MS a complementary view on both corrosion resistance, as well as on changes
+in surface morphology/adhesion of the SAM is possible. Protection from
+oxidative dissolution is higher with hydrophobic SAMs, which detach under
+micelle formation, while the hydrophilic SAM exhibits lower protective effects
+on gold dissolution rates, although it stays intact as highly mobile layer
+under anodic polarization. The developed multi-technique approach will prove
+useful for studying the interfacial activity and corrosion suppression
+mechanism of inhibiting molecules on other metals and alloys.",2105.00280v1
+2021-05-04,Ostwald ripening in an oxide-on-metal system,"Ostwald ripening is a well-known physicochemical phenomenon in which smaller
+particles, characterized by high surface energy, dissolve and feed the bigger
+ones that are thermodynamically more stable. The effect is commonly observed in
+solid and liquid solutions, as well as in systems consisting of supported metal
+clusters or liquid droplets. Here, we provide the first evidence for the
+occurrence of Ostwald ripening in an oxide-on-metal system which, in our case,
+consists of ultrathin iron monoxide (FeO) islands grown on Ru(0001)
+single-crystal support. The results reveal that the thermally-driven sintering
+of islands allows altering their fine structural characteristics, including
+size, perimeter length, defect density and stoichiometry, which are crucial,
+e.g., from the point of view of heterogeneous catalysis.",2105.01229v2
+2021-05-04,First Demonstration of Robust Tri-Gate \b{eta}-Ga2O3 Nano-membrane Field-Effect Transistors Operated Up to 400 °C,"Nano-membrane tri-gate beta-gallium oxide (\b{eta}-Ga2O3) field-effect
+transistors (FETs) on SiO2/Si substrate fabricated via exfoliation have been
+demonstrated for the first time. By employing electron beam lithography, the
+minimum-sized features can be defined with a 50 nm fin structure. For
+high-quality interface between \b{eta}-Ga2O3 and gate dielectric, atomic
+layer-deposited 15-nm-thick aluminum oxide (Al2O3) was utilized with
+Tri-methyl-aluminum (TMA) self-cleaning surface treatment. The fabricated
+devices demonstrate extremely low subthreshold slope (SS) of 61 mV/dec, high
+drain current (IDS) ON/OFF ratio of 1.5 X 109, and negligible transfer
+characteristic hysteresis. We also experimentally demonstrated robustness of
+these devices with current-voltage (I-V) characteristics measured at
+temperatures up to 400 {\deg}C.",2105.01721v1
+2021-05-06,Anticorrosion and biocompatibility of a functionalized layer formed on ZK60 Mg alloy via hydroxyl ion implantation,"Magnesium and its alloys have aroused tremendous interests because of their
+promising mechanical properties and biocompatibility. However, their
+excessively fast corrosion rate hinders the development of Mg alloys in the
+biomedical fields. Inspired by conventional ion implantation, a less-toxic
+functional group (hydroxyl) is used as the ion source to bombard the ZK60 Mg
+alloy surface to form a functionalized oxide layer. This functionalized oxide
+layer significantly facilitates the corrosion resistance of the ZK60 Mg alloy
+substrate and the proliferation of MC3T3-E1 cells, which is confirmed by
+electrochemical, immersion, and in vitro cytocompatibility tests. In comparison
+with results of ZK60 alloy implanted with carboxyl ions in our previous work,
+it is concluded that hydroxyl-treated alloys exhibit slightly higher corrosion
+rate while better biocompatibility. In summary, less-toxic functional ion
+implantation can be an effective strategy for inhibiting corrosion of Mg alloy
+implants and promoting their biocompatibility.",2105.02558v1
+2021-05-05,High Permittivity Dielectric Field-Plated Vertical (001) $β$-Ga$_2$O$_3$ Schottky Barrier Diode with Surface Breakdown Electric Field of 5.45 MV/cm and BFOM of $>$ 1 GW/cm$^{2}$,"This paper presents vertical (001) oriented $\beta$-Ga$_2$O$_3$ field plated
+(FP) Schottky barrier diode (SBD) with a novel extreme permittivity dielectric
+field oxide. A thin drift layer of 1.7 $\mu m$ was used to enable a
+punch-through (PT) field profile and very low differential specific
+on-resistance (R$_{on-sp}$) of 0.32 m$\Omega$-cm$^{2}$. The extreme
+permittivity field plate oxide facilitated the lateral spread of the electric
+field profile beyond the field plate edge and enabled a breakdown voltage
+($V_{br}$) of 687 V. The edge termination efficiency increases from 13.5 $\%$
+for non-field plated structure to 63 $\%$ for high permittivity field plate
+structure. The surface breakdown electric field was extracted to be 5.45 MV/cm
+at the center of the anode region using TCAD simulations. The high permittivity
+field plated SBD demonstrated a record high Baliga figure of merit (BFOM) of
+1.47 GW/cm$^{2}$ showing the potential of Ga$_2$O$_3$ power devices for
+multi-kilovolt class applications.",2105.04413v1
+2021-05-10,Understanding Carbon Contamination in Proton Conducting Oxides,"Carbon contamination is a significant concern for proton-conducting oxides in
+the cerate and zirconate family, particularly for BaCeO$_3$. Here, we use
+first-principles calculations to evaluate carbon stability in SrCeO$_3$,
+BaCeO$_3$, SrZrO$_3$, and BaZrO$_3$. The cerates require more carbon-poor
+environments to prevent carbonate formation, though this requirement can be
+loosened through the use of more oxygen-poor growth conditions. Carbonate
+formation is not the only concern, however. We find that interstitial carbon
+has lower formation energies in the cerates relative to the zirconates, leading
+to higher carbon concentrations that compete with the desired oxygen vacancy
+formation. We also examine the mobility of carbon interstitials, finding that
+both migration barriers and binding energies to acceptors are lower in the
+cerates. As a result, the cerates are likely to degrade when exposed to carbon
+at operating temperatures. Our results show definitively why the cerates are
+less stable than the zirconates with respect to carbon and elucidate the
+mechanisms contributing to their instability, thereby helping to explain why
+alloying with zirconium will enhance their operational efficiency.",2105.04640v1
+2021-05-10,Continuous wave laser thermal restoration of oxidized lead-based pigments in mural paintings,"Red lead and lead white are some of the most ancient and common pigments in
+mural paintings. However, they tend to blacken with time due to their oxidation
+to plattnerite (\b{eta}-PbO2). The possibility to induce the reconversion
+reactions by CW laser heating is hereby discussed. A thermodynamic study by TGA
+showed that direct cerussite or hydrocerussite formation from plattnerite are
+not suitable reconversion routes, which was confirmed by laser irradiation
+trials under CO2 and CO2/H2O fluxes. Minium (Pb3O4) and subsequent massicot
+(\b{eta}-PbO) formation from plattnerite were achieved (confirmed by SEM-EDS,
+XRD and micro-Raman) under Ar+, 810 nm diode and Nd:YAG lasers. The latter
+appears to be the most suited for restauration purposes, given the broad minium
+reconversion irradiance range. This is confirmed by successful trials on
+macroscopic areas of naturally darkened red lead containing samples.",2105.04677v2
+2021-05-18,Rashba dominated spin-splitting in the bulk ferroelectric oxide perovskite KIO3,"The momentum-dependent Rashba and Dresselhaus spin-splitting has gained much
+attention for its highly promising applications in spintronics. In the present
+work, ab initio density functional theory calculations are performed to study
+the spin-splitting effect in ferroelectric oxide perovskite KIO3. Our
+calculations are additionally supported by symmetry adapted two-band k.p
+Hamiltonian. Non-negligible spin-splitting effect is observed at conduction
+band minimum (CBm) and valence band maximum (VBM) for rhombohedral R3m and R3c
+phases. Linear Rashba terms successfully explain the splitting at VBM. However,
+cubic terms become important in realizing spin-orientation near CBm. Our
+results show the enhancement in Rashba parameters on tuning the ferroelectric
+order parameter. Further, we have observed reversal of spin-orientation on
+switching the direction of polarization.",2105.08452v1
+2021-05-19,Ferroelectricity promoted by cation/anion divacancies in SrMnO$_3$,"We investigate the effect of polar Sr-O vacancy pairs on the electric
+polarization of SrMnO$_3$ (SMO) thin films using density functional theory
+(DFT) calculations. This is motivated by indications that ferroelectricity in
+complex oxides can be engineered by epitaxial strain but also \textit{via} the
+defect chemistry. Our results suggest that intrinsic doping by cation and anion
+divacancies can induce a local polarization in unstrained non-polar SMO thin
+films and that a ferroelectric state can be stabilized below the critical
+strain of the stoichiometric material. This polarity is promoted by the
+electric dipole associated with the defect pair and its coupling to the atomic
+relaxations upon defect formation that polarize a region around the defect.
+This suggests that polar defect pairs affect the strain-dependent
+ferroelectricity in semiconducting antiferromagnetic SMO. For metallic
+ferromagnetic SMO we find a much weaker coupling between the defect dipole and
+the polarization due to much stronger electronic screening. Coupling of
+defect-pair dipoles at high enough concentrations along with their switchable
+orientation thus makes them a promising route to affect the ferroelectric
+transition in complex transition metal oxide thin films.",2105.09360v1
+2021-05-20,In-situ X-ray analysis of misfit strain and curvature of bent polytypic GaAs-In(x)Ga(1-x)As core-shell nanowires,"Misfit strain in core-shell nanowires can be elastically released by nanowire
+bending in case of asymmetric shell growth around the nanowire core. In this
+work, we investigate the bending of GaAs nanowires during the asymmetric
+overgrowth by an In(x)Ga(1-x)As shell caused by avoiding substrate rotation. We
+observe that the nanowire bending direction depends on the nature of the
+substrate's oxide layer, demonstrated by Si substrates covered by native and
+thermal oxide layers. Further, we follow the bending evolution by time-resolved
+in-situ X-ray diffraction measurements during the deposition of the asymmetric
+shell. The XRD measurements give insight into the temporal development of the
+strain as well as the bending evolution in the core-shell nanowire.",2105.09665v1
+2021-05-25,A decatungstate-based Ionic liquid exhibiting very low dielectric constant suitable for acting as solvent and catalyst for oxidation of organic substrates,"In this contribution, a new POM-based ionic liquid, namely
+(P6,6,6,14)4[W10O32], was fully characterized. Its viscosity and its very low
+dielectric constant make this hybrid ionic liquid suitable to be used as
+solvent for organic transformations. As proof of concept, this unique ionic
+liquid combining solvant and catalyst properties was tested for catalytic
+oxidation of various alcohols and alkenes in presence of H2O2",2105.11714v1
+2021-05-27,Pushing the Study of Point Defects in Thin Film Ferrites to Low Temperatures Using In Situ Ellipsometry,"Unveiling point defects concentration in transition metal oxide thin films is
+essential to understand and eventually control their functional properties,
+employed in an increasing number of applications and devices. Despite this
+unquestionable interest, there is a lack of available experimental techniques
+able to estimate the defect chemistry and equilibrium constants in such oxides
+at intermediate-to-low temperatures. In this study, the defect chemistry of a
+relevant material such as La1-xSrxFeO3-d (LSF) with (x = 0.2, 0.4 and 0.5
+(LSF20, LSF40 and LSF50 respectively) is obtained by using a novel in situ
+spectroscopic ellipsometry approach applied to thin films. Through this
+technique, the concentration of holes in LSF is correlated to measured optical
+properties and its evolution with temperature and oxygen partial pressure is
+determined. In this way, a systematic description of defect chemistry in LSF
+thin films in the temperature range from 350dC to 500dC is obtained for the
+first time, which represents a step forward in the understanding of LSF20,
+LSF40 and LSF50 for emerging low temperature applications.",2105.13039v1
+2021-05-28,Nafion-induced reduction of manganese and its impact on the electrocatalytic properties of a highly active MnFeNi oxide for bifunctional oxygen conversion,"Electrocatalysts for bifunctional oxygen reduction (ORR) and oxygen evolution
+reaction (OER) are commonly studied under hydrodynamic conditions, rendering
+the use of binders necessary to ensure the mechanical stability of the
+electrode films. The presence of a binder, however, may influence the
+properties of the materials under examination to an unknown extent. Herein, we
+investigate the impact of Nafion on a highly active ORR/OER catalyst consisting
+of MnFeNi oxide nanoparticles supported on multi-walled carbon nanotubes.
+Electrochemical studies revealed that, in addition to enhancing the mechanical
+stability and particle connectivity, Nafion poses a major impact on the ORR
+selectivity, which correlates with a decrease in the valence state of Mn
+according to X-ray absorption spectroscopy. These findings call for awareness
+regarding the use of electrode additives, since in some cases the extent of
+their impact on the properties of electrode films cannot be regarded as
+negligible.",2105.13888v1
+2021-05-31,Effect of Zr and Al Addition on Nanocluster Formation in Oxide Dispersion Strenghthened Steel-an ab initio Study,"Conventional Oxide dispersion strengthened steels are characterized by
+thermally stable, high density of Y-Ti-O nanoclusters, which are responsible
+for their high creep strength. Ti plays a major role in obtaining a high
+density of ultrafine particles of optimum size range of 2-10 nm. In
+Al-containing ODS steels developed for corrosion resistance, Y-Al-O clusters
+formed are of size range 20 -100 nm, and Ti fails in making dispersions finer
+in the presence of Al. Usage of similar alloying elements like Zr in place of
+Ti is widely considered. In this study, binding energies of different stages of
+Y-Zr-O-Vacancy and Y-Al-O-Vacancy complexes in the bcc Iron matrix are studied
+by first-principle calculations. It is shown that in all the stages of
+formation, Y-Zr-O-Vacancy clusters have higher binding energy than
+Y-Al-O-Vacancy clusters and hence in ferritic steel containing both Zr and Al,
+Y-Zr-O-Vacancy clusters are more stable and more favored to nucleate than
+Y-Al-O-Vacancy clusters. The bonding nature in each stage is analyzed using
+charge density difference plots for the plausible reason for higher stability
+of Y-Zr-O-Vacancy clusters.",2105.15063v1
+2021-06-02,Environmental Sensitivity of Fabry-Perot Microcavities Induced By Layered Graphene-Dielectric Hybrid Coatings,"We propose a fiber-based environmental sensor that exploits the reflection
+phase shift tunability provided by the use of layered coatings composed of
+dielectric slabs spaced by conducting membranes. A transfer matrix study is
+done in a simplified theoretical model, for which an enhanced sensitivity of
+the reflection interference pattern to the output medium is demonstrated, in
+the typical refractive index range of liquid media. An experimental
+configuration using a cascaded Fabry-Perot microcavity coated by a graphene
+oxide/polyethylenimine (GO/PEI) multilayered structure is demonstrated. Its
+cost effective chemical production method makes graphene oxide-based hybrid
+coatings excellent candidates for future real-life sensing devices.",2106.01287v2
+2021-06-06,"Modeling Temperature, Frequency, and Strain Effects on the Linear Electro-Optic Coefficients of Ferroelectric Oxides","An electro-optic modulator offers the function of modulating the propagation
+of light in a material with electric field and enables seamless connection
+between electronics-based computing and photonics-based communication. The
+search for materials with large electro-optic coefficients and low optical loss
+is critical to increase the efficiency and minimize the size of electro-optic
+devices. We present a semi-empirical method to compute the electro-optic
+coefficients of ferroelectric materials by combining first-principles
+density-functional theory calculations with Landau-Devonshire phenomenological
+modeling. We apply the method to study the electro-optic constants, also called
+Pockels coefficients, of three paradigmatic ferroelectric oxides: BaTiO3,
+LiNbO3, and LiTaO3. We present their temperature-, frequency- and
+strain-dependent electro-optic tensors calculated using our method. The
+predicted electro-optic constants agree with the experimental results, where
+available, and provide benchmarks for experimental verification.",2106.02998v3
+2021-06-07,Efficiency limits of Perovskite Solar Cells with Transition Metal Oxides as Hole Transport Layers,"Transition metal oxides (TMOs) like MoOx are increasingly explored as hole
+transport layers for perovskite-based solar cells. Due to their large work
+function, the hole collection mechanism of such solar cells are fundamentally
+different from other materials like PEDOT: PSS, and the associated device
+optimizations are not well elucidated. In addition, the prospects of such
+architectures against the challenges posed by ion migration are yet to be
+explored - which we critically examine in this contribution through detailed
+numerical simulations. Curiously, we find that, for similar ion densities and
+interface recombination velocities, ion migration is more detrimental for
+Perovskite solar cells with TMO contact layers with much lower achievable
+efficiency limits (21%). The insights shared by this work should be of broad
+interest to the community in terms of long-term stability, efficiency
+degradation and hence could help critically evaluate the promises and prospects
+of TMOs as hole contact layers for perovskite solar cells.",2106.03881v1
+2021-06-08,Increased hole mobility in anti-ThCr$_2$Si$_2$-type La$_2$O$_2$Bi co-sintered with alkaline earth metal oxides for oxygen intercalation and hole carrier doping,"Metallic anti-ThCr$_2$Si$_2$-type $RE_2$O$_2$Bi ($RE$ = rare earth) with Bi
+square nets show superconductivity while insulating La$_2$O$_2$Bi shows high
+hole mobility, by expanding the c-axis length through oxygen intercalation. In
+this study, alkaline earth metal oxides (CaO, SrO, and BaO) were co-sintered
+with La$_2$O$_2$Bi. CaO and BaO served as oxygen intercalants without
+incorporation of Ca and Ba in La$_2$O$_2$Bi. On the other hand, SrO served as
+not only oxygen intercalant but also hole dopant via Sr substitution with La in
+La$_2$O$_2$Bi. The oxygen intercalation and hole doping resulted in expansion
+of the c-axis length, contributing to improved electrical conduction. In
+addition, the hole mobility was enhanced up to 150 cm$^2$V$^{-1}$s$^{-1}$ in
+La$_2$O$_2$Bi, which almost doubles the mobility in previous study.",2106.04717v1
+2021-06-18,Electrical tuning of the spin-orbit interaction in nanowire by transparent ZnO gate grown by atomic layer deposition,"We develop an InAs nanowire gate-all-around field-effect transistor using a
+transparent conductive zinc oxide (ZnO) gate electrode, which is in-situ atomic
+layer deposited after growth of gate insulator of Al2O3. We perform
+magneto-transport measurements and find a crossover from weak localization to
+weak antilocalization effect with increasing gate voltage, which demonstrates
+that the Rashba spin-orbit coupling is tuned by the gate electrode. The
+efficiency of the gate tuning of the spin-orbit interaction is higher than
+those obtained for two-dimensional electron gas, and as high as that for a
+gate-all-around nanowire metal-oxide-semiconductor field-effect transistor that
+was previously reported. The spin-orbit interaction is discussed in line with
+not only conventionally used one-dimensional model but also recently proposed
+model that considers effects of microscopic band structures of materials.",2106.10036v1
+2021-06-21,Nanocrystalline superconducting $γ$-Mo$_2$N ultra-thin films for single-photon detectors,"We analyze the influence of the surface passivation produced by oxides on the
+superconducting properties of $\gamma$-Mo$_2$N ultra-thin films. The
+superconducting critical temperature of thin films grown directly on Si (100)
+with those using a buffer and a capping layer of AlN are compared. The results
+show that the cover layer avoids the presence of surface oxides, maximizing the
+superconducting critical temperature for films with thicknesses of a few
+nanometers. We characterize the flux-flow instability measuring current-voltage
+curves in a 6.4 nm thick Mo$_2$N film with a superconducting critical
+temperature of 6.4 K. The data is analyzed using the Larkin and Ovchinnikov
+model. Considering self-heating effects due to finite heat removal from the
+substrate, we determine a fast quasiparticle relaxation time $\approx$ 45 ps.
+This value is promising for its applications in single-photon detectors.",2106.10781v1
+2021-07-13,Spatiotemporal refraction of light in an epsilon-near-zero ITO layer,"When light travels through a medium in which the refractive index is rapidly
+changing with time, the light will undergo a shift in its frequency. Large
+frequency shifting effects have recently been reported for transparent
+conductive oxides. These observations have been interpreted as emerging from
+temporal changes to the propagation phase in a bulk medium resulting from
+temporal variations in the refractive index, an effect referred to as temporal
+refraction. Here, we show that the frequency shift in an epsilon-near-zero
+(ENZ) layer made of indium tin oxide (ITO) originates not only from this bulk
+response, but includes a significant effect resulting from temporal changes to
+the spatial boundary conditions. This boundary effect can lead to a dominant
+opposing shift to the bulk effect for certain angles. Hence, this process gives
+rise to a frequency shift that can be tailored through the angle of incidence,
+decoupling the amplitude and phase modulation.",2107.05970v1
+2021-07-23,Controlled oxygen plasma treatment of single-walled carbon nanotube films improves osteoblast cells attachment and enhances their proliferation,"The effects of oxidative treatment of single-walled carbon nanotubes (SWCNTs)
+on the adhesion and proliferation of human osteoblasts (SAOS-2) were
+investigated. The surface properties of SWCNTs after oxygen plasma treatment
+were characterised by contact angle measurement, scanning electron microscopy
+and Raman spectroscopy. The immunofluorescent staining of vinculin, actin
+filaments and nuclei was used to probe cell adhesion and growth on SWCNT films.
+Our results show that adhesion and proliferation of human osteoblasts
+cultivated on SWCNT films indeed depends on the degree of an oxidative
+treatment. As an optimal procedure was found the treatment with oxygen plasma
+for 5 min. In the latter case the osteoblasts form a confluent layer with
+pronounced focal adhesions throughout the entire cell body. The optimal
+conditions compromise the effect of hydrophilic character of SWCNT films and
+the level of damage of SWCNT surface.",2107.11294v1
+2021-07-25,Formation of Copper oxide II in polymer solution-blow-spun fibers and the successful non-woven ceramic production,"Copper oxide II is a p-type semiconductor that can be used in several
+applications. Focusing on producing such material using an easy and low-cost
+technique, we followed an acetate one-pot-like route for producing a polymer
+precursor solution with different acetates:PVP (polyvinylpyrrolidone) weight
+ratios. Then, composite nanofibers were produced using the solution blow
+spinning (SBS) technique. The ceramic CuO samples were obtained after a
+calcination process at 600 oC for two hours, applying a heating rate of 0.5
+oC/min. Non-woven fabric-like ceramic samples with average diameters lower than
+300 nm were successfully obtained. SEM images show relatively smooth fibers
+with a granular morphology. XRD shows the formation of randomly oriented grains
+of CuO. In addition, FTIR and XRD analyses show the CuO formation before the
+heat treatment. Thus, a chemical reaction sequence was proposed to explain the
+results.",2107.11704v1
+2021-07-26,Fracture and Fatigue of Thin Crystalline SrTiO$_3$ Membranes,"The increasing availability of a variety of two-dimensional materials has
+generated enormous growth in the field of nanoengineering and nanomechanics.
+Recent developments in thin film synthesis have enabled the fabrication of
+freestanding functional oxide membranes that can be readily incorporated in
+nanomechanical devices. While many oxides are extremely brittle in bulk, recent
+studies have shown that, in thin membrane form, they can be much more robust to
+fracture as compared to their bulk counterparts. Here, we investigate the
+ultimate tensile strength of SrTiO$_3$ membranes by probing freestanding
+SrTiO$_3$ drumheads using an atomic force microscope. We demonstrate that
+SrTiO$_3$ membranes can withstand an elastic deformation with an average strain
+of ~6% in the sub-20 nm thickness regime, which is more than an order of
+magnitude beyond the bulk limit. We also show that these membranes are highly
+resilient upon a high cycle fatigue test, surviving up to a billion cycles of
+force modulation at 85% of their fracture strain, demonstrating their high
+potential for use in nanomechanical applications.",2107.12468v1
+2021-08-20,Thickness Dependent OER Electrocatalysis of Epitaxial LaFeO$_{3}$ Thin Films,"Transition metal oxides have long been an area of interest for water
+electrocatalysis through the oxygen evolution and oxygen reduction reactions.
+Iron oxides, such as LaFeO$_{3}$, are particularly promising due to the
+favorable energy alignment of the valence and conduction bands comprised of
+Fe$^{3+}$ cations and the visible light band gap of such materials. In this
+work, we examine the role of band alignment on the electrocatalytic oxygen
+evolution reaction (OER) in the intrinsic semiconductor LaFeO$_{3}$ by growing
+epitaxial films of varying thicknesses on Nb-doped SrTiO$_{3}$. Using cyclic
+voltammetry and electrochemical impedance spectroscopy, we find that there is a
+strong thickness dependence on the efficiency of electrocatalysis for OER.
+These measurements are understood based on interfacial band alignment in the
+system as confirmed by layer-resolved electron energy loss spectroscopy and
+electrochemical Mott-Schottky measurements. Our results demonstrate the
+importance of band engineering for the rational design of thin film
+electrocatalysts for renewable energy sources.",2108.09360v1
+2021-08-20,Nonreciprocal ENZ-Dielectric Bilayers: Enhancement of Nonreciprocity from a Nonlinear Transparent Conducting Oxide Thin Film at Epsilon-Near-Zero (ENZ) Frequency,"We envision the use of an indium tin oxide (ITO) thin film as part of a
+bi-layered silicon-photonics subwavelength device to boost
+nonlinearity-assisted all-passive nonreciprocal behavior. The asymmetric
+p-polarized oblique excitation of a mode near the epsilon-near-zero (ENZ)
+frequency, with highly-confined and enhanced normal electric field component
+and large absorption, allows to harness ITO's strong ultrafast nonlinear
+response for the generation of a notable nonreciprocal performance in the
+two-port element. Though limited by loss, we find the device's optimal
+operational point and the maximum nonreciprocal transmittance ratio attainable
+vs. light intensity -- including an apparent upper bound slightly over 2 --,
+and we perform exhaustive numerical simulations considering nonlinear processes
+of both anharmonic and thermal nature that validate our predictions, including
+steady-state and pulsed-laser excitations.",2108.09381v1
+2021-08-23,Z$_2$ nontrivial topology of rare-earth binary oxide superconductor,"Recently, superconductivity has been discovered in rock-salt structured
+binary lanthanum monoxide LaO through state-of-the-art oxide thin-film epitaxy.
+In this work, we reveal that the normal state of superconducting LaO is a $Z_2$
+nontrivial topological metal, where the Dirac point protected by the crystal
+symmetry is located around the Fermi energy. By analysing the orbital
+characteristics, we show that the nature of the topological band structure of
+LaO originates from the intra-atomic transition from the outer shell La 5$d$ to
+the inner shell 4$f$ orbitals driven by the strong octahedral crystal-field.
+Furthermore, the appearance of novel surface states unambiguously demonstrates
+the topological signature of LaO superconductor. Our theoretical findings not
+only shed new light into the understanding of the exotic quantum behaviors in
+LaO superconductor with intimate correlation between 4$f$ and 5$d$ orbitals in
+La, but also provide an exciting platform to explore the interplay between
+nontrivial topology and superconductivity.",2108.10063v2
+2021-08-24,Non-classical nucleation of zinc oxide from a physically-motivated machine-learning approach,"Observing non-classical nucleation pathways remains challenging in
+simulations of complex materials with technological interests. This is because
+it requires very accurate force fields that can capture the whole complexity of
+their underlying interatomic interactions and an advanced structural analysis.
+Here, we first report the construction of a machine-learning force field for
+zinc oxide interactions using the Physical LassoLars Interaction Potentials
+approach which allows us to be predictive even for untrained structures. Then,
+we carried out freezing simulations from a liquid and observed the crystal
+formation with atomistic precision. Our results, which are analyzed using a
+data-driven approach based on bond order parameters, demonstrate the presence
+of both prenucleation clusters and two-step nucleation scenarios thus
+retrieving seminal predictions of non-classical nucleation pathways made on
+much simpler models.",2108.10601v2
+2021-08-25,Variational quantum eigensolver techniques for simulating carbon monoxide oxidation,"A family of Variational Quantum Eigensolver (VQE) methods is designed to
+maximize the resource of existing noisy intermediate-scale quantum (NISQ)
+devices. However, VQE approaches encounter various difficulties in simulating
+molecules of industrially relevant sizes, among which the choice of the ansatz
+for the molecular wavefunction plays a crucial role. In this work, we push
+forward the capabilities of adaptive variational algorithms (ADAPT-VQE) by
+demonstrating that the measurement overhead can be significantly reduced via
+adding multiple operators at each step while keeping the ansatz compact. Within
+the proposed approach, we simulate a set of molecules, O$_2$, CO, and CO$_2$,
+participating in the carbon monoxide oxidation processes using the statevector
+simulator and compare our findings with the results obtained using VQE-UCCSD
+and classical methods. Based on these results, we estimate the energy
+characteristics of the chemical reaction. Our results pave the way to the use
+of variational approaches for solving practically relevant chemical problems.",2108.11167v3
+2021-09-01,"Recent Progress on Synthesis, Characterization, and Applications of Metal Halide Perovskites@Metal Oxide","Metal halide perovskites (MHPs) have become a promising candidate in a myriad
+of applications, such as light-emitting diodes, solar cells, lasing,
+photodetectors, photocatalysis, transistors, etc. This is related to the
+synergy of their excellent features, including high photoluminescence quantum
+yields, narrow and tunable emission, long charge carrier lifetimes, broad
+absorption spectrum along with high extinction absorptions coefficients, among
+others. However, the main bottleneck is the poor stability of the MHPs under
+ambient conditions. This is imposing severe restrictions with respect to their
+industrialized applications and commercialization. In this context, metal oxide
+(MOx) coatings have recently emerged as an efficient strategy towards
+overcoming the stabilities issues as well as retain the excellent properties of
+the MHPs, and therefore facilitate the development of the related devices
+stabilities and performances.This review provides a summary of the recent
+progress on synthetic methods, enhanced features, the techniques to assess the
+MHPs-MOxcomposites, and applications of the MHPs@MOx.Specially, novel
+approaches to fabricate the composites and new applications of the composites
+are also reported in this review for the first time. This is rounded by a
+critical outlook about the current MHPs stability issues and the further
+direction to ensure a bright future of MHPs@MOx",2109.00508v1
+2021-09-04,Physical limits of ultra-high-finesse optical cavities: Taming two-level systems of glassy metal oxides,"The framework of tunnelling states in amorphous media provides the
+dissipative mechanism that imposes fundamental limits on the performances of
+ultra-high-Q optical and microwave resonators. In the optical domain, however,
+the microscopic nature of the tunnelling states and their direct consequences
+to the optical losses have not been characterized. In this work, we examine the
+interplay between glassy physics and stoichiometric point defects of
+ultra-low-loss dielectric mirrors, with a focus on two-level systems of oxygen
+defects in metal oxide, Ta$_2$O$_5$. In the context of ultra-high-finesse
+optical cavities, we characterize the Urbach tail of Ta$_2$O$_5$ under thermal
+annealing and reactive oxygen plasma. For the first time, we microscopically
+resolve the individual oxygen point defects on the mirror surfaces and
+introduce laser-assisted annealing to selectively ""cure"" surface defects. By
+exploiting these techniques, we report the realization of ultra-high-finesse
+optical cavity with finesse $\mathcal{F}=450,000$ and the absorption-scatter
+loss $ 0.1 \pm 0.2$ ppm at $852$ nm.",2109.01856v1
+2021-09-05,Discovery and Engineering of Low Work Function Perovskite Materials,"Materials with low work functions are critical for an array of applications
+requiring the facile removal or efficient transport of electrons through a
+device. Perovskite oxides are a promising class of materials for finding low
+work functions, and here we target applications in thermionic and field
+electron emission. Perovskites have highly malleable compositions which enable
+tunable work function values over a wide range, robust stability at high
+temperatures, and high electronic conductivities. In this work, we screened
+over 2900 perovskite oxides in search of stable, conductive, low-work-function
+materials using Density Functional Theory (DFT) methods. Our work provides
+insight into the materials chemistry governing the work function value of a
+perovskite, where materials with barely filled d bands possess the lowest work
+functions. Our screening has resulted in a total of seven promising compounds,
+such as BaMoO3 and SrNb0.75Co0.25O3 with work functions of 1.1 eV and 1.5 eV,
+respectively. These promising materials and others presented in this study may
+find use as low work function electron emitters in high power vacuum electronic
+and thermionic energy conversion devices. Moreover, the database of calculated
+work functions and materials chemistry trends governing the value of the work
+function may aid in the engineering of perovskite heterojunction devices.",2109.02005v1
+2021-09-14,Sparse expansions of multicomponent oxide configuration energy using coherency & redundancy,"Compressed sensing has become a widely accepted paradigm to construct high
+dimensional cluster expansion models used for statistical mechanical studies of
+atomic configuration in complex multicomponent crystalline materials. However,
+strict sampling requirements necessary to obtain minimal coherence measurements
+for compressed sensing to guarantee accurate estimation of model parameters are
+difficult and in some cases impossible to satisfy due to the inability of
+physical systems to access certain configurations. Nevertheless, the dependence
+of energy on atomic configuration can still be adequately learned without these
+strict requirements by using compressed sensing by way of coherent measurements
+using redundant function sets known as frames. We develop a particular frame
+constructed from the union of all occupancy-based cluster expansion basis sets.
+We illustrate how using this highly redundant frame yields sparse expansions of
+the configuration energy of complex oxide materials that are competitive and
+often surpass the prediction accuracy and sparsity of models obtained from
+standard cluster expansions.",2109.06905v2
+2021-09-17,Effect of Buffer Termination on Intermixing and Conductivity in LaTiO$_3$/SrTiO$_3$ Heterostructures Integrated on Si(100),"The control of chemical exchange across heterointerfaces formed between
+ultra-thin functional transition-metal oxide layers provides an effective route
+to manipulate the electronic properties of these systems. We show that cationic
+exchange across the interface between the Mott insulator, LaTiO$_3$(LTO) grown
+epitaxially on SrTiO$_3$(STO)-buffered Silicon by molecular beam epitaxy
+depends strongly on the surface termination of the strained STO buffer. Using a
+combination of temperature-dependent transport and synchrotron X-ray crystal
+truncation rods and reciprocal space mapping, an enhanced conductivity in
+STO/LTO/SrO- terminated STO buffers compared to heterostructures with
+TiO$_2$-terminated STO buffers is correlated with La/Sr exchange and the
+formation of metallic La$_{1-x}$Sr$_x$TiO$_3$. La/Sr exchange effectively
+reduces the strain energy of the system due to the large lattice mismatch
+between the nominal oxide layers and the Si substrate.",2109.08586v1
+2021-09-27,"Layered, Tunable Graphene Oxide-Nylon Heterostructures for Wearable Electrocardiogram Sensors","Nanoscale engineered materials combined with wearable wireless technologies
+can deliver a new level of health monitoring. A reduced graphene oxide-nylon
+composite material is developed and tested, demonstrating its usefulness as a
+material for sensors in wearable, long-term electrocardiogram (ECG) monitoring
+via a comparison to one of the widely used ECG sensors. The structural analysis
+by scanning electron (SEM) and atomic force microscopy (AFM) shows a limited
+number of defects on a macroscopic scale. Fourier Transform Infrared (FTIR) and
+Raman spectroscopy confirm the presence of rGOx, and the ratio of D- and
+G-features as a function of thickness correlates with the resistivity analysis.
+The negligible effect of the defects and the tunability of electrical and
+optical properties, together with live ECG data, demonstrate its signal
+transduction capability.",2109.12739v2
+2021-09-27,Surface Reduction State Determines Stabilization and Incorporation of Rh on α-Fe2O3(1-102),"Iron oxides (FeOx) are among the most common support materials utilized in
+single atom catalysis. The support is nominally Fe2O3, but strongly reductive
+treatments are usually applied to activate the as-synthesized catalyst prior to
+use. Here, we study Rh adsorption and incorporation on the (1-102) surface of
+hematite ({\alpha}-Fe2O3), which switches from a stoichiometric (1x1)
+termination to a reduced (2x1) reconstruction in reducing conditions. Rh atoms
+form clusters at room temperature on both surface terminations, but Rh atoms
+incorporate into the support lattice as isolated atoms upon annealing above 400
+{\deg}C. Under mildly oxidizing conditions, the incorporation process is so
+strongly favoured that even large Rh clusters containing hundreds of atoms
+dissolve into the surface. Based on a combination of low energy ion scattering
+and scanning tunnelling microscopy data, as well as density functional theory,
+we conclude that the Rh atoms are stabilized in the immediate subsurface,
+rather than the surface layer.",2109.13084v1
+2021-09-29,"Nonreciprocal transport in a Rashba ferromagnet, delafossite PdCoO$_2$","Rashba interfaces yield efficient spin-charge interconversion and give rise
+to nonreciprocal transport phenomena. Here, we report magnetotransport
+experiments in few-nanometer-thick films of PdCoO$_2$, a delafossite oxide
+known to display a large Rashba splitting and surface ferromagnetism. By
+analyzing the angle dependence of the first- and second-harmonic longitudinal
+and transverse resistivities, we identify a Rashba-driven unidirectional
+magnetoresistance that competes with the anomalous Nernst effect below the
+Curie point. We estimate a Rashba coefficient of 0.75 {\pm} 0.3 eV {\AA} and
+argue that our results qualify delafossites as a new family of oxides for
+nano-spintronics and spin-orbitronics, beyond perovskite materials.",2109.14503v1
+2021-10-02,The role of surface spin polarization on ceria-supported Pt nanoparticles,"In this work, we employ first-principles simulations to investigate the spin
+polarization of CeO$_2$-(111) surface and its impact on interactions between a
+ceria support and Pt nanoparticles. For the first time, we report that the
+CeO$_2$-(111) surface exhibits a robust surface spin polarization due to the
+internal charge transfer between atomic Ce and O layers. In turn, it can lower
+the surface oxygen vacancy formation energy and enhance the oxide reducibility.
+We show that the inclusion of spin polarization can therefore significantly
+reduce the major activation barrier in the proposed reaction pathway of CO
+oxidation on ceria-supported Pt nanoparticles. For metal-support interactions,
+surface spin polarization enhances the bonding between Pt nanoparticle and
+ceria surface oxygen, while CO adsorption on Pt nanoparticles weakens the
+interfacial interaction regardless of spin polarization.",2110.00710v1
+2021-10-07,A Modern-day Alchemy: Double Glow Plasma Surface Metallurgy Technology,"In the long history of science and technology development, one goal is to
+diffuse solid alloy elements into the surface of steel materials to form
+surface alloys with excellent physical and chemical properties. On the basis of
+plasma nitriding technology, double glow plasma surface metallurgy technology
+has answered this challenge. This technology, which seems to be a modern-day
+alchemy, can use any element in the periodic table of chemical elements,
+including solid metal elements and their combinations, to form many types of
+surface alloyed layers with high hardness, wear resistance, corrosion
+resistance and high temperature oxidation resistance on various metal
+materials. For examples, nickel base alloys, stainless steels and high speed
+steels are formed on the surfaces of ordinary carbon steels; and high hardness,
+wear resistance and high temperature oxidation resistance alloy are formed on
+the surface of titanium alloy.This article briefly introduces the formation and
+principle of double glow plasma surface metallurgy technology, and summarizes
+the experimental results and industry application. The significance and
+development prospect of this technology are discussed.",2110.03236v1
+2021-10-08,Charge capacity characteristics of a Lithium Nickel-Cobalt-Aluminium Oxide battery show fractional-derivative behavior,"Batteries experience capacity offset where available charge depends on the
+rate at which this charge is drawn. In this work we analyze the capacity offset
+of a 4.8 A h lithium nickel-cobalt-aluminium oxide battery using an equivalent
+circuit model of a fractional capacitor in series with a resistor. In this
+case, the available charge, in theory, becomes infinite in the limit of
+infinitesimal rate. We show that the fractional properties of the capacitor can
+be extracted from the charge against rate plot. We then use a network of RC
+elements to represent the fractional capacitor in order to simulate the data
+with Matlab. We find that the fractional exponent alpha obtained in this way,
+0.971, agrees with that obtained in a more traditional manner from an impedance
+versus frequency plot, although the fractional capacity does not. Such an
+approach demonstrates the importance of a fractional description for capacity
+offset even when an element is nearly a pure capacitor and is valuable for
+predictions of state-of-charge when low currents are drawn.",2110.03883v1
+2021-10-12,High-mobility field-effect transistor using 2-dimensional electron gas at the LaScO3/BaSnO3 interface,"A novel 2-dimensional electron gas (2DEG) system with high-mobility was
+discovered at the interface of two perovskite oxides, a polar orthorhombic
+perovskite LaScO3 (LSO) and a nonpolar cubic perovskite BaSnO3 (BSO). Upon
+depositing the LSO film on the BSO film, the conductance enhancement and the
+resulting 2DEG density (n2D) was measured. Comparing the results with the
+previously reported LaInO3/BaSnO3 (LIO/BSO) polar interface, we applied the
+interface polarization model to the LSO/BSO system, in which the polarization
+exists only over 4 pseudocubic unit cells in LSO from the interface and
+vanishes afterward like the LIO/BSO interface. Based on the calculations of the
+self-consistent Poisson-Schrodinger equations, the LSO thickness dependence of
+n2D of LSO/BSO heterointerface is consistent with this model. Furthermore, a
+single subband in the quantum well is predicted. Using the conductive interface
+and the LSO as a gate dielectric, a 2DEG transistor composed of only perovskite
+oxides with high field-effect mobility (uFE) close to 100 cm2 V-1 s-1 is
+demonstrated.",2110.05738v1
+2021-10-18,Ambipolar Property of Isolated Hydrogen in Oxide Materials Revealed by Muon,"The study on the electronic state of muon as pseudo-hydrogen (represented by
+the elemental symbol Mu) has long been appreciated as one of the few methods to
+experimentally access the electronic state of dilute hydrogen (H) in
+semiconductors and dielectrics. Meanwhile, theoretical predictions on the
+electronic state of H in these materials by first-principles calculations using
+density functional theory (DFT) do not always agree with the observed states of
+Mu, standing as an obstacle to integrating the findings of both Mu and H. In
+this paper, we provide resolution to this problem by a semi-quantitative model
+that enables systematic understanding of the electronic states of Mu in most
+oxides.",2110.09024v2
+2021-10-27,Understanding the nonlinear optical response of epsilon near zero materials in the time-domain,"The promise of active nanophotonics technology relies on the confinement and
+control of light at the nanoscale. Confinement via plasmonics, dielectric
+resonators, and waveguides can be complemented with materials whose optical
+properties can be controlled using nonlinear effects. Transparent conducting
+oxides (TCOs) exhibit strong optical nonlinearities in their near zero
+permittivity spectral region, on the femtosecond time-scale. Harnessing full
+control over the nonlinear response requires a deeper understanding of the
+process. To achieve this, we develop a self-consistent time-domain model for
+the nonlinear optical response of TCOs and implement it into a
+three-dimensional finite-difference time-domain code. We compare and tune our
+simulation tools against recently published experimental results for intense
+laser irradiation of thin indium tin oxide (ITO) films. Finally, by simulating
+intense laser irradiation of ITO-based plasmonic metasurfaces, we demonstrate
+the full power of our approach. As expected, we find validating the significant
+enhancement of the nonlinear response of an ITO-based metasurface over bare ITO
+thin films. Our work thus enables quantitative nanophotonics design with
+epsilon-near-zero materials.",2110.14806v1
+2021-11-01,Induced Giant Piezoelectricity in Centrosymmetric Oxides,"Piezoelectrics are materials that linearly deform in response to an applied
+electric field. As a fundamental prerequisite, piezoelectric material must
+possess a non centrosymmetric crystal structure. For more than a century, this
+remains the major obstacle for finding new piezoelectric materials. We
+circumvent this limitation by breaking the crystallographic symmetry, and
+inducing large and sustainable piezoelectric effects in centrosymmetric
+materials by electric field induced rearrangement of oxygen vacancies
+Surprisingly, the results show the generation of extraordinarily large
+piezoelectric responses d33 ~200,000 pm/V), in cubic fluorite Gd-doped CeO2-x
+films, which is two orders of magnitude larger than in the presently best known
+lead based piezoelectric relaxor ferroelectric oxide. These findings open
+opportunities to design new piezoelectric materials from environmentally
+friendly centrosymmetric ones.",2111.00829v3
+2021-11-02,Local laser oxidation of titanium film for post-fabrication trimming of photonic integrated circuits,"Local laser oxidation of a thin titanium film is considered as a means of a
+precise adjustment of losses and effective refractive index of dielectric
+optical waveguides. A fine phase control of an operating point and extinction
+ratio enhancement up to 57 dB were demonstrated using an integrated optical
+Ti:LiNbO3 Mach-Zehnder modulator. This technique only slightly affects the
+dielectric waveguide material and is very promising for a high precision
+permanent trimming of photonic devices based on dielectric waveguides of
+different material platforms and fabrication technologies.",2111.02884v2
+2021-11-04,Glass-like Electronics in Vanadium Dioxide,"Functional materials can offer new paradigms for miniaturized and
+energy-efficient electronics, providing a complementary or even alternative
+platform to metal-oxide-semiconductors. Here we report on electronically
+accessible long-lived structural states in Vanadium Dioxide that can offer a
+scheme for data storage and processing. We show that such states can be
+electrically manipulated and tracked beyond 10,000 seconds after excitation,
+exhibiting similar features of glasses, which are beyond the classic
+metastability in Mott systems. Glass-like electronics can potentially overcome
+some of the fundamental limitations in conventional metal-oxide-semiconductor
+electronics, and open avenues for neuromorphic computation and multi-level
+memories.",2111.03181v1
+2021-10-07,Chlorine-free electrochemical disinfection using graphene sponge electrodes,"Graphene sponge electrodes were employed for chlorine-free inactivation of
+Escherichia coli from low conductivity water. The nitrogen-doped reduced
+graphene oxide (NRGO) sponge anode bearing more positive charge achieved
+complete E. coli inactivation (i.e., 5 log removal) in the anode-cathode
+configuration at 115 A m-2, versus 2.6 log removal using boron-doped reduced
+graphene oxide sponge anode. The bacteria were mainly inactivated via
+electrosorption and electroporation, as confirmed by the scanning electron
+microscopy. Storage of the electrochemically treated samples revealed further
+killing of the bacteria due to the damaged cell membranes. When using real tap
+water, 5.5 log E. coli removal required 5.70 kWh m-3, which was drastically
+lowered to 1.38 kWh m-3 using intermittent current and thus exploiting the
+capacitive properties of graphene. The developed graphene sponge anode does not
+form any chlorine, chlorate, or perchlorate, and holds great promise for
+efficient electro-disinfection without forming toxic disinfection byproducts.",2111.05252v1
+2021-11-11,Simulation of lateral ion migration during electroforming process,"Non-volatile memory devices have received a lot of interest in both industry
+and academia in the last decade. Transition metal oxide-based memories offer
+potential applications as universal memory and artificial synapses. Here we
+focus on the one-time conditioning of metal / oxide / metal structures leading
+to the formation of a conducting filament in TiN/TaxO1-x/TiN structures and
+develop a finite element model of this process. Model solved coupled equations
+for charge, heat, and mass transport with the last one including concentration,
+temperature, and stress gradients as driving forces. The results closely
+replicated available structural data such as diameter and composition of
+Ta-enriched core of the filament, O-enriched ring around it, and the dynamics
+of filament formation. The range of critical material parameters, namely heats
+of transport for Ta and O, is discussed.",2111.06215v1
+2021-11-20,Contact conductance governs metallicity in conducting metal oxide nanocrystal films,"In bulk semiconductor materials, the insulator-metal transition (IMT) is
+governed by the concentration of conduction electrons. Meanwhile, even when
+fabricated from metallic building blocks, nanocrystal films are often
+insulating with inter-nanocrystal contacts acting as electron transport
+bottlenecks. Using a library of transparent conducting tin-doped indium oxide
+nanocrystal films with varied electron concentration, size, and contact area,
+we test candidate criteria for the IMT and establish a phase diagram for
+electron transport behavior. From variable temperature conductivity
+measurements, we learn that both the IMT and a subsequent crossover to
+conventional metallic behavior near room temperature are governed by the
+conductance of the inter-nanocrystal contacts. To cross the IMT,
+inter-nanocrystal coupling must be sufficient to overcome the charging energy
+of a nanocrystal, while conventional metallic behavior requires contact
+conductance to reach the conductance of a nanocrystal. This understanding can
+enable the design and fabrication of metallic conducting materials from
+nanocrystal building blocks.",2111.10576v2
+2021-11-25,Tuning Coherent-Phonon Heat Transport in LaCoO$_3$/SrTiO$_3$ Superlattices,"Accessing the regime of coherent phonon propagation in nanostructures opens
+enormous possibilities to control the thermal conductivity in energy harvesting
+devices, phononic circuits, etc. In this paper we show that coherent phonons
+contribute substantially to the thermal conductivity of LaCoO3/SrTiO3 oxide
+superlattices, up to room temperature. We show that their contribution can be
+tuned through small variations of the superlattice periodicity, without
+changing the total superlattice thickness. Using this strategy, we tuned the
+thermal conductivity by 20% at room temperature. We also discuss the role of
+interface mixing and epitaxial relaxation as an extrinsic, material dependent
+key parameter for understanding the thermal conductivity of oxide
+superlattices.",2111.13035v1
+2021-12-06,Cerium Oxides without $U$: The Role of Many-Electron Correlation,"Electron transfer with changing occupation in the 4f subshell poses a
+considerable challenge for quantitative predictions in quantum chemistry. Using
+the example of cerium oxide, we identify the main deficiencies of common
+parameter-dependent one-electron approaches, such as density functional theory
+(DFT) with a Hubbard correction, or hybrid functionals. As a response, we
+present the first benchmark of ab initio many-electron theory for electron
+transfer energies and lattice parameters under periodic boundary conditions. We
+show that the direct random phase approximation clearly outperforms all DFT
+variations. From this foundation, we, then, systematically improve even
+further. Periodic second-order M{\o}ller-Plesset perturbation theory meanwhile
+manages to recover standard hybrid functional values. Using these approaches to
+eliminate parameter bias allows for highly accurate benchmarks of strongly
+correlated materials, the reliable assessment of various density functionals,
+and functional fitting via machine-learning.",2112.02850v1
+2021-12-07,Pressure-Dependent Phase Transitions in Hybrid Improper Ferroelectric Ruddlesden-Popper Oxides,"The temperature-dependent phase transitions in Ruddlesden-Popper oxides with
+perovskite bilayers have been under increased scrutiny in recent years due to
+the so-called hybrid improper ferroelectricity that some chemical compositions
+exhibit. However, little is currently understood about the hydrostatic pressure
+dependence of these phase transitions. Herein we present the results of a
+high-pressure powder synchrotron X-ray diffraction experiment and $ab~initio$
+calculations on the bilayered Ruddlesden-Popper phases Ca$_{3}$Mn$_{2}$O$_{7}$
+and Ca$_{3}$Ti$_{2}$O$_{7}$. In both compounds we observe a first-order phase
+transition between polar $A2_{1}am$ and non-polar $Acaa$ structures.
+Interestingly, we show that while the application of pressure ultimately
+favours a non-polar phase -- as is commonly observed for proper ferroelectrics
+-- regions of response exist where pressure actually acts to increase the polar
+mode amplitudes. The reason for this can be untangled by considering the varied
+response of octahedral tilts and rotations to hydrostatic pressure and their
+trilinear coupling with the polar instability.",2112.03819v1
+2021-12-09,Valley splitting in silicon from the interference pattern of quantum oscillations,"We determine the energy splitting of the conduction-band valleys in
+two-dimensional (2D) electrons confined in silicon metal oxide semiconductor
+(Si-MOS) Hall-bar transistors. These Si-MOS Hall bars are made by advanced
+semiconductor manufacturing on 300 mm Si wafers and support a 2D electron gas
+of high quality with a maximum mobility of 17.6$\times$10$^3$cm$^2$/Vs and
+minimum percolation density of 3.45$\times$10$^{10}$cm$^{-2}$. Because of the
+low disorder, we observe beatings in the Shubnikov-de Haas oscillations that
+arise from the energy-split two low-lying conduction band valleys. From the
+analysis of the oscillations beating patterns up to T = 1.7 K, we estimate a
+maximum valley splitting of 8.2 meV at a density of
+6.8$\times$10$^{12}$cm$^{-2}$. Furthermore, the valley splitting increases with
+density at a rate consistent with theoretical predictions for a near-ideal
+semiconductor/oxide interface.",2112.05032v3
+2021-12-10,Extraordinary strain hardening from dislocation loops in defect-free Al nanocubes,"The interaction of crystalline defects leads to strain hardening in bulk
+metals. Metals with high stacking fault energy (SFE), such as aluminum, tend to
+have low strain hardening rates due to an inability to form stacking faults and
+deformation twins. Here, we use in situ SEM mechanical compressions to find
+that colloidally synthesized defect-free 114 nm Al nanocubes combine a high
+linear strain hardening rate of 4.1 GPa with a high strength of 1.1 GPa. These
+nanocubes have a 3 nm self-passivating oxide layer that has a large influence
+on mechanical behavior and the accumulation of dislocation structures.
+Post-compression TEM imaging reveals stable prismatic dislocation loops and the
+absence of stacking faults. MD simulations relate the formation of dislocation
+loops and strain hardening to the surface oxide. These results indicate that
+slight modifications to surface and interfacial properties can induce enormous
+changes to mechanical properties in high SFE metals.",2112.05723v1
+2021-12-16,Dynamics of water and ethanol in graphene oxide,"We utilized the momentum transfer(Q)-dependence of Quasi-Elastic Neutron
+Scattering (QENS) to reveal the dynamics of water and ethanol confined in
+Graphene Oxide (GO) powder or membranes at different temperatures and in
+different orientations. The dynamics was measured across different length and
+time scales using several spectrometers. We found reduced diffusivities (up to
+30\% in the case of water) and a depression of the transition temperatures.
+While water showed near Arrhenius behavior with an almost bulk-like activation
+barrier in a temperature range of 280-310 K, the diffusivity of ethanol showed
+little temperature dependence. For both water and ethanol, we found evidence
+for immobile and mobile fractions of the confined liquid. The mobile fraction
+exhibited jump diffusion, with a jump length consistent with the expected
+average spacing of hydroxide groups in the GO surfaces. From anisotropy
+measurements, we found weak anisotropy in diffusion, with the surprising result
+that diffusion was faster perpendicular to membrane than parallel to it.",2112.09235v1
+2021-12-17,"A generalized 3D elastic model for nanoscale, self-assembled oxide-metal thin films with pillar-in-matrix configurations","In recent years, functional oxide-metal based vertically aligned
+nanocomposite (VAN) thin films have gained interest due to their intriguing
+physical properties and multifunctionalities stemming from the complex
+interactions between the two phases in the film and the substrate. In this
+work, we develop a model for studying the energetics of these thin film
+systems, including the effects of both lattice mismatch and capillary forces
+due to interface curvature. Each phase is incorporated into the model using a
+phase indicator function, and we introduce the capillary forces as body forces
+using a vector density representation of the interface. The model is
+implemented using the finite element method to study the deformation of the
+thin film which is composed of Au nanopillars embedded in a La0.7Sr0.3MnO3
+(LSMO) matrix on an SrTiO3 (STO) substrate. The results suggest that the total
+energy is lowest for random configurations of pillars compared to ordered
+square and hexagonal lattice configurations, consistent with the random
+distribution of pillars found in experiments. Furthermore, we find that the
+interfacial energy dominates the total energy of each configuration, suggesting
+that interfacial energy in the system is an important design parameter for
+nanocomposite growth, along with the lattice mismatch.",2112.09281v1
+2021-12-22,Understanding Hot Carrier Reliability in FinFET Technology from Trap-based Approach,"In this paper, the recent advances of our studies on hot carrier degradation
+(HCD) are presented from trap-based approach. The microscopic speculation of
+interface trap generation is carried out by time-dependent DFT (TDDFT)
+simulation in ""real-time"". Two types of oxide traps contributing to HCD are
+identified from experiments. Combining the contributions of interface and oxide
+traps, a unified compact model has been proposed which can accurately predict
+hot carrier degradation and variation in full Vgs/Vds bias. The trap locations,
+degradation contributions and temperature dependence are studied in detail. In
+addition, the mixed mode reliability of HCD-BTI coupling through self-heating
+and under off-state stress are discussed.",2112.11753v1
+2022-01-05,Nitrogen Plasma Passivated Niobium Resonators for Superconducting Quantum Circuits,"Microwave loss in niobium metallic structures used for superconducting
+quantum circuits is limited by a native surface oxide layer formed over a
+timescale of minutes when exposed to an ambient environment. In this work, we
+show that nitrogen plasma treatment forms a niobium nitride layer at the
+metal-air interface which prevents such oxidation. X-ray photoelectron
+spectroscopy confirms the doping of nitrogen more than 5 nm into the surface
+and a suppressed oxygen presence. This passivation remains stable after aging
+for 15 days in an ambient environment. Cryogenic microwave characterization
+shows an average filling factor adjusted two-level-system loss tangent
+$\rm{F\delta_{TLS}}$ of $(2.9\pm0.5)\cdot10^{-7}$ for resonators with 3
+$\rm{\mu}$m center strip and $(1.0\pm0.3)\cdot10^{-7}$ for 20 $\rm{\mu}$m
+center strip, exceeding the performance of unpassivated samples by a factor of
+four.",2201.01776v2
+2022-01-17,Ternary Metal Oxide Substrates for Superconducting Circuits,"Substrate material imperfections and surface losses are one of the major
+factors limiting superconducting quantum circuitry from reaching the scale and
+complexity required to build a practicable quantum computer. One potential path
+towards higher coherence of superconducting quantum devices is to explore new
+substrate materials with a reduced density of imperfections due to inherently
+different surface chemistries. Here, we examine two ternary metal oxide
+materials, spinel (MgAl2O4) and lanthanum aluminate (LaAlO3), with a focus on
+surface and interface characterization and preparation. Devices fabricated on
+LaAlO3 have quality factors three times higher than earlier devices, which we
+attribute to a reduction in interfacial disorder. MgAl2O4 is a new material in
+the realm of superconducting quantum devices and, even in the presence of
+significant surface disorder, consistently outperforms LaAlO3. Our results
+highlight the importance of materials exploration, substrate preparation, and
+characterization to identify materials suitable for high-performance
+superconducting quantum circuitry.",2201.06228v1
+2022-01-21,Tuning Catalytic Activity and Selectivity in Photocatalysis on Dielectric Cuprous Oxide Particles,"Dye degradation has been for more than forty years in the scientific
+community. All these studies have primarily focused on breaking various dyes
+using catalysts driven by either light or heat. Most studies started to focus
+on metal-oxides after the discovery of water-splitting by TiO2. Among the many
+catalysts used plasmonic metal nanostructures have been explored significantly
+in recent times due to their special property called localized surface plasmon
+resonances (LSPR). However, facing multiple problems of heat losses and
+instability, people started to focus on dielectric medium-to-high refractive
+indexed materials for photonic applications. Most of these dielectric materials
+have been studied from a physics point of view and less from chemistry. In this
+work, we have focused on how these materials can be used for tuning selectivity
+through wavelength-dependent studies by performing methylene blue (MB) dye
+degradation.",2201.08828v2
+2022-01-24,Study of voltage cycling conditions on Pt oxidation and dissolution in polymer electrolyte fuel cells,"This paper is devoted to study the electrochemical behavior of Pt catalyst in
+a polymer electrolyte fuel cell at various operating conditions and at
+different electric potential difference (also known as voltage) cycling applied
+in accelerated stress tests. The degradation of platinum is considered with
+respect to the Pt ion dissolution and the Pt oxide coverage of catalyst
+described by a one-dimensional model. In the model, degradation rate increases
+with temperature and decreasing particle diameter of Pt nano-particles. The
+theoretical study of the underlying diffusion system with the nonlinear
+reactions is presented by analytical methods and gives explicit solutions
+through a first integral of the ODE system. Numerical tests are obtained using
+a second order implicit-explicit scheme. The computer simulation shows that the
+lifetime of the catalyst depends on the voltage profile and the upper potential
+level. By this Pt mass loss is more significant at the membrane surface than at
+the gas diffusion layer.",2201.09768v1
+2022-01-28,Mass transport via in-plane nanopores in graphene oxide membranes,"Angstrom confined solvents in two-dimensional laminates travel through
+interlayer spacings, gaps between adjacent sheets, and via in plane pores.
+Among these, experimental access to investigate the mass transport through in
+plane pores is lacking. Here, we create these nanopores in graphene oxide
+membranes via ion irradiation with precise control over functional groups, pore
+size and pore density. Low ion induced pore densities result in mild reduction
+and increased water permeation for the membranes. Higher pore densities lead to
+pronounced reduction and complete blockage of pure water however allows
+permeation of ethanol water mixture due to weakening of hydrogen network. We
+confirm with simulations, that the attraction of the solvents towards the pores
+with functional groups and disruption of the angstrom confined hydrogen network
+is crucial to allow in plane pore transport.",2201.11886v1
+2022-01-31,Towards Optimized Charge Transport in Multilayer Reduced Graphene Oxides,"In the context of graphene-based composite applications, a complete
+understanding of charge conduction in multilayer reduced graphene oxides (rGO)
+is highly desirable. However, these rGO compounds are characterized by multiple
+and different sources of disorder depending on the chemical method used for
+their synthesis. Most importantly the precise role of interlayer interaction in
+promoting or jeopardizing electronic flow remains unclear. Here, thanks to the
+development of a multiscale computational approach combining first-principles
+calculations with large scale transport simulations, the transport scaling laws
+in multilayer rGO are unraveled, explaining why diffusion worsens with
+increasing film thickness. In contrast, contacted films are found to exhibit an
+opposite trend when the mean free path becomes shorter than the channel length,
+since conduction becomes predominantly driven by interlayer hopping. These
+predictions are favourably compared with experimental data and open a road
+towards the optimization of graphene-based composites with improved electrical
+conduction.",2201.13437v1
+2022-02-14,Role of lithium intercalation in fluorine-doped tin oxide thin films: Ab-initio calculations and experiment,"Using a combination of experimental techniques and density functional theory
+(DFT) calculations, the influence of lithium insertion on the electronic and
+electrochemical properties of fluourine-doped SnO$_2$ (FTO) is assessed. For
+this purpose, we investigate the electrochromic behavior of commercial FTO
+electrode embedded in a solution of lithium perclorate (LiClO$_4$). The
+electrochromic properties are evaluated by UV-VIS spectroscopy, cyclic
+voltammetry, and chronoamperometry. These tests show that FTO exhibits
+electrochromism with a respectable coloration efficiency ($\eta=47.9$ cm$^2$/C
+@ 637 nm). DFT study indicates that lithium remains ionized in the lattice,
+raising the Fermi level about 0.7 eV deep into the conduction band. X-ray
+photoelectron spectroscopy (XPS) is used to study chemical bonding and
+oxidation states. XPS analysis of the Sn 3d core levels reveals that lithium
+insertion in FTO induces a shift of 350 meV in the Sn 3d states suggesting that
+lithium is incorporated into the SnO$_2$ lattice.",2202.07083v1
+2022-02-18,Molecular dynamics study of the linear viscoelastic shear and bulk relaxation moduli of poly(tetramethylene oxide) (PTMO),"Here we report the linear viscoelastic properties of amorphous
+poly(tetramethylene oxide) (PTMO), which is one of the key components in
+synthesizing segmented polyurethane (PU) elastomers. The temperature and
+molecular weight dependent viscoelastic behavior is investigated in detail by
+computing the shear relaxation modulus G(t) and the bulk relaxation modulus
+K(t), using the Green-Kubo relationship with correlation function. Our results
+provide new data for PTMO melt from the united atom model and also extend the
+existing knowledge of viscoelastic properties of polymers in general. The
+predicted viscoelastic behavior range is shifted on a master curve using the
+time-temperature superposition principle (TTSP) with horizontal and vertical
+shift factors. The emerging shift factors agree with the Williams-Landel-Ferry
+(WLF) equation. For the validation of the united-atom model of PTMO using the
+TraPPE-UA force field we explored the transport properties and observed a
+position-dependent diffusion dynamics throughout the polymer chain, which
+subsequently influences the scaling laws for chain dynamics. These findings are
+discussed in terms of emerging experimental evidence on position dependent
+displacement for different chain portions along the chain length.",2202.08993v1
+2022-03-03,Direct observation of local antiferroelectricity induced phonon softening at a SrTiO3 defect,"Defects in oxides usually exhibit exotic properties that may be associated
+with the local lattice dynamics. Here, at atomic spatial resolution, we
+directly measure phonon modes of an antiphase boundary (APB) in SrTiO3
+freestanding membrane and correlate them with the picometer-level structural
+distortion. We find that the SrTiO3 APB introduces new defect phonon modes that
+are absent in bulk SrTiO3. These modes are highly sensitive to the subtle
+structure distortion, i.e., the SrTiO3 APB generates the local electric dipoles
+forming an antiferroelectric configuration, which significantly softens the
+transverse optical (TO) and longitudinal optical (LO) modes at {\Gamma} point.
+Correlating the local phonons with the subtle structural distortion, our
+findings provide valuable insights into understanding the defect properties in
+complex oxides and essential information for their applications such as
+thermoelectric devices.",2203.01772v1
+2022-03-15,High-Temperature Decomposition of Diisopropyl Methylphosphonate (DIMP) on Alumina: Mechanistic Predictions from Ab Initio Molecular Dynamics,"The enhanced degradation of organophosphorous-based chemical warfare agents
+(CWAs) on metal-oxide surfaces holds immense promise for neutralization
+efforts; however, the underlying mechanisms in this process remain poorly
+understood. We utilize large-scale quantum calculations for the first time to
+probe the high-temperature degradation of diisopropyl methylphosphonate (DIMP),
+a nerve agent simulant. Our Born-Oppenheimer molecular dynamics (BOMD)
+calculations show that the $\gamma$-Al$_2$O$_3$ surface shows immense promise
+for quickly adsorbing and destroying CWAs. We find that the alumina surface
+quickly adsorbs DIMP at all temperatures, and subsequent decomposition of DIMP
+proceeds via a propene elimination. Our BOMD calculations are complemented with
+metadynamics simulations to produce free energy paths, which show that the
+activation barrier decreases with temperature and DIMP readily decomposes on
+$\gamma$-Al$_2$O$_3$. Our first-principle BOMD and metadynamics simulations
+provide crucial diagnostics for sarin decomposition models and mechanistic
+information for examining CWA decomposition reactions on other candidate metal
+oxide surfaces.",2203.08035v1
+2022-03-23,"Low-energy electron microscopy intensity-voltage data -- factorization, sparse sampling, and classification","Low-energy electron microscopy (LEEM) taken as intensity-voltage (I-V) curves
+provides hyperspectral images of surfaces, which can be used to identify the
+surface type, but are difficult to analyze. Here, we demonstrate the use of an
+algorithm for factorizing the data into spectra and concentrations of
+characteristic components (FSC3) for identifying distinct physical surface
+phases. Importantly, FSC3 is an unsupervised and fast algorithm. As example
+data we use experiments on the growth of praseodymium oxide or ruthenium oxide
+on ruthenium single crystal substrates, both featuring a complex distribution
+of coexisting surface components, varying in both chemical composition and
+crystallographic structure. With the factorization result a sparse sampling
+method is demonstrated, reducing the measurement time by 1-2 orders of
+magnitude, relevant for dynamic surface studies. The FSC3 concentrations are
+providing the features for a support vector machine (SVM) based supervised
+classification of the types. Here, specific surface regions which have been
+identified structurally, via their diffraction pattern, as well as chemically
+by complementary spectro-microscopic techniques, are used as training sets. A
+reliable classification is demonstrated on both exemplary LEEM I-V datasets.",2203.12353v1
+2022-03-25,On-Demand Activation of Photochromic Nanoheaters for High Color Purity 3D Printing,"The creation of white and multicoloured 3D-printed objects with high colour
+fidelity via powder sintering processes is currently limited by discolouration
+from thermal sensitizers used in the printing process. Here we circumvent this
+problem by using switchable, photochromic tungsten oxide nanoparticles, which
+are colourless even at high concentrations. Upon ultraviolet illumination, the
+tungsten oxide nanoparticles can be reversibly activated making them highly
+absorbing in the infrared. Their strong infrared absorption upon activation
+renders them efficient photothermal sensitizers that can act as fusing agents
+for polymer powders in sintering-based 3D printing. The WO3 nanoparticles show
+fast activation times, and when mixed with polyamide powders they exhibit a
+heating-to-colour-change ratio greatly exceeding other sensitizers in the
+literature. Upon mixing with coloured inks, powders containing WO3 display
+identical colouration to a pristine powder. This demonstrates the potential of
+WO3, and photochromic nanoparticles in general as a new class of material for
+advanced manufacturing.",2203.13584v1
+2022-03-29,Thermal decomposition of hydrated graphite oxide: A computational study,"We study the behavior of hydrated graphite oxide (GO) at high temperatures
+using thermally accelerated molecular dynamics simulations based on ab initio
+density functional theory. Our results suggest that GO, a viable candidate for
+water treatment and desalination membranes, is more heat resilient than
+currently used organic materials. The system we consider to represent important
+aspects of thermal processes in highly disordered GO is a hydrated GO bilayer
+in vacuum. Our study provides microscopic insight into reactions involving
+water and functional epoxy-O and OH-groups bonded to graphene layers, and also
+describes the swelling of the structure by water vapor pressure at elevated
+temperatures. We find the system to withstand simulation temperatures up to
+${\approx}$2,500 K before the graphitic layers start decomposing, implying the
+possibility of cleaning biofouling residue from a GO-based membrane by heating
+in an inert gas atmosphere.",2203.15891v1
+2022-04-05,Cr (VI) biosorption at different Na (I) concentrations after Zn(II) uptake during Arthrobacter species growth,"The biosorption of Cr(VI) Arthrobacter species (Arthrobacter globiformis 151B
+and Arthrobacter oxides 61B) after growth in the presence of Zn (II) ions at
+different Na (I) concentrations was studied application using dialysis and
+atomic absorption analysis. It was shown that after absorption of Zn(II) during
+growth of types of Arthrobacter the biosorption of Cr (VI) with types
+Arthrobacter (Arthrobacter globiformis 151B, Arthrobacter oxidas 61B) increases
+at various concentration of Na (I) comparative without Zn(II), at identical
+concentration of Na (I). It is seen, that zinc(II) ions promote for Cr(VI) part
+of the active centers of Arthrobacter species and Na(I) ions already has
+relatively little effect on them. However, this change is more pronounced for
+Cr (VI) _Arthrobacter globiformis 151B + Zn (II) than for Cr (VI) _Arthrobacter
+oxides of 61B + Zn (II).",2204.02309v1
+2022-04-17,A phase field model combined with genetic algorithm for polycrystalline hafnium zirconium oxide ferroelectrics,"Ferroelectric hafnium zirconium oxide (HZO) thin films show significant
+promise for applications in ferroelectric random-access memory, ferroelectric
+field-effect transistors, and ferroelectric tunneling junctions. However, there
+are shortcomings in understanding ferroelectric switching, which is crucial in
+the operation of these devices. Here a computational model based on phase field
+method is developed to simulate the switching behavior of polycrystalline HZO
+thin films. Furthermore, we introduce a novel approach to optimize the
+effective Landau coefficients describing the free energy of HZO by combining
+the phase field model with a genetic algorithm. We validate the model by
+accurately simulating switching curves for HZO thin films with different
+ferroelectric phase fractions. The simulated domain dynamics during switching
+also shows amazing similarity to the available experimental observations. The
+present work also provides fundamental insights into enhancing the
+ferroelectricity in HZO thin films by controlling grain morphology and
+crystalline texture. It can potentially be extended to improve the
+ferroelectric properties of other hafnia based thin films.",2204.07960v2
+2022-04-28,Interplay of the disorder and strain in gallium oxide,"Ion irradiation is a powerful tool to tune properties of semiconductors and,
+in particular, of gallium oxide (Ga2O3) which is a promising ultra-wide bandgap
+semiconductor exhibiting phase instability for high enough strain/disorder
+levels. In the present paper we observed an interesting interplay between the
+disorder and strain in monoclinic \b{eta}-Ga2O3 single crystals by comparing
+atomic and cluster ion irradiations as well as atomic ions co-implants. The
+results obtained by a combination of the channeling technique, x-ray
+diffraction and theoretical calculations show that the disorder accumulation in
+\b{eta}-Ga2O3 exhibits superlinear behavior as a function of the collision
+cascade density. Moreover, the level of strain in the implanted region can be
+engineered by changing the disorder conditions in the near surface layer. The
+results can be used for better understanding of the radiation effects in
+\b{eta}-Ga2O3 and imply that disorder/strain interplay provides an additional
+degree of freedom to maintain desirable strain in Ga2O3, potentially applicable
+to modify the rate of the polymorphic transitions in this material.",2204.13302v2
+2022-04-30,A Gate-All-Around Single-Channel In2O3 Nanoribbon FET with Near 20 mA/μm Drain Current,"In this work, we demonstrate atomic-layer-deposited (ALD) single-channel
+indium oxide (In2O3) gate-all-around (GAA) nanoribbon FETs in a
+back-end-of-line (BEOL) compatible process. A maximum on-state current (ION) of
+19.3 mA/{\mu}m (near 20 mA/{\mu}m) is achieved in an In2O3 GAA nanoribbon FET
+with a channel thickness (TIO) of 3.1 nm, channel length (Lch) of 40 nm,
+channel width (Wch) of 30 nm and dielectric HfO2 of 5 nm. The record high drain
+current obtained from an In2O3 FET is about one order of magnitude higher than
+any conventional single-channel semiconductor FETs. This extraordinary drain
+current and its related on-state performance demonstrate ALD In2O3 is a
+promising oxide semiconductor channel with great opportunities in BEOL
+compatible monolithic 3D integration.",2205.00360v1
+2022-05-02,Recent advances in inorganic oxides-based resistive random-access memory devices,"Memory has always been a building block element for information technology.
+Emerging technologies such as artificial intelligence, big data, the internet
+of things, etc., require a novel kind of memory technology that can be energy
+efficient and have an exception data retention period. Among several existing
+memory technologies, resistive random-access memory (RRAM) is an answer to the
+above question as it is necessary to possess the combination of speed of RAM
+and nonvolatility, thus proving to be one of the most promising candidates to
+replace flash memory in next-generation non-volatile RAM applications. This
+review discusses the existing challenges and technological advancements made
+with RRAM, including switching mechanism, device structure, endurance, fatigue
+resistance, data retention period, and mechanism of resistive switching in
+inorganic oxides material used as a dielectric layer. Finally, a summary and a
+perspective on future research are presented.",2205.05537v1
+2022-05-29,Polarimetric characterization of segmented mirrors,"We study the impact of the loss of axial symmetry around the optical axis on
+the polarimetric properties of a telescope with segmented primary mirror when
+each segment is present in a different aging stage. The different oxidation
+stage of each segment as they are substituted in time leads to non-negligible
+crosstalk terms. This effect is wavelength dependent and it is mainly
+determined by the properties of the reflecting material. For an aluminum
+coating, the worst polarimetric behavior due to oxidation is found for the blue
+part of the visible. Contrarily, dust -- as modeled in this work -- does not
+significantly change the polarimetric behavior of the optical system .
+Depending on the telescope, there might be segment substitution sequences that
+strongly attenuate this instrumental polarization.",2205.14640v1
+2022-06-07,The Origin of Deformation Induced Topological Anisotropy in Silica Glass,"Oxide glasses with a network structure are omnipresent in daily life. Often,
+they are regarded as isotropic materials; however, structural anisotropy can be
+induced through processing in mechanical fields and leads to unique materials
+properties. Unfortunately, due to the lack of local, atomic-scale analysis
+methods, the microscopic mechanisms leading to anisotropy remained elusive.
+Using novel analysis methods on glasses generated by molecular dynamics
+simulations, this paper provides a microscopic understanding of topological
+anisotropy in silica (SiO$_2$) glass under mechanical loads. The anisotropy
+observed in silica glass originates from a preferred orientation of SiO$_4$
+tetrahedra at both short- and medium-range levels that can be controlled via
+the mode of mechanical loading. The findings elucidate the relation between the
+deformation protocol and the resulting anisotropic structure of the silica
+network (involving both persistent and transient effects), and thus provide
+important insight for the design of oxide glasses with tailored materials
+properties.",2206.03039v2
+2022-06-23,Conditions for the formation of pure birnessite during the oxidation of Mn(II) cations in aqueous alkaline medium,"Birnessite was synthetized through redox reaction by mixing MnO4-, Mn2+ and
+OH- solutions. The Mn(VII): Mn(II) ratio of 0.33 was chosen and three methods
+were used consisting in a quick mixing under vigorous stirring of two of the
+three reagents and then on the dropwise addition of the third one. The obtained
+solids were characterized by XRD, FTIR and XPS spectroscopies. Their average
+oxidation states were determined from ICP and CEC measurements while their
+surface properties were investigated by XPS. This study provides an increased
+understanding of the importance of dissolved oxygen in the formation of
+birnessite and hausmannite and shows the ways to obtain pure birnessite. The
+role of counter-ion ie. Na+ or K+ was also examined.",2206.11550v1
+2022-07-04,New insight into 3-picoline - deuterium oxide (D$_2$O) mixtures of limited miscibility with the lower critical consolute temperature,"Coexistence curves in mixtures of limited miscibility with the lower critical
+consolute temperature (LCT), of 3-picoline with deuterium oxide (D$_2$O), and
+D2O/H2O have been determined. They were tested with respect to the order
+parameter, the diameter of the binodal, and coordinates of the critical
+consolute point (critical temperature Tc and critical concentration fic)
+Studies were carried out using the innovative method based on the analysis of
+relative volumes occupied by coexisting phases, yielding high-resolution data.
+The clear violation of the Cailletet-Mathew law of rectilinear diameter for the
+LCT mixtures of limited miscibility is evidenced. For the order parameter, the
+new distortion-sensitive analysis method yielded the evidence for the
+model-value of the order parameter critical exponent beta = 0.326.up to ca. 1 K
+from Tc. Finally, the simple & easy method for determining the critical
+concentration by testing relative volumes of coexisting phases (or
+alternatively fractional meniscus heights, h) is presented. The significance of
+the invariant value hc(Tc, fic) = 1/2 is highlighted. The appearance of the
+milky & bluish critical opalescence is also shown",2207.01670v1
+2022-07-06,Co-operative Influence of O2 and H2O in the Degradation of Layered Black Arsenic,"Layered black arsenic (b-As) has recently emerged as a new anisotropic
+two-dimensional (2D) semiconducting material with applications in electronic
+devices. Understanding factors affecting the ambient stability of this material
+remains crucial for its applications. Herein we use first-principles density
+functional theory (DFT) calculations to examine the stability of the (010) and
+(101) surfaces of b-As in the presence of oxygen (O2) and water (H2O). We show
+that the (101) surface of b-As can easily oxidize in presence of O2. In the
+presence of moisture contained in air, the oxidized b-As surfaces favorably
+react with H2O molecules to volatilize As in the form of As(OH)3 and AsO(OH),
+which results in the degradation of the b-As surface, predominantly across the
+(101) surface. These predictions are in good agreement with experimental
+electron microscopy observations, thus demonstrating the co-operative
+reactivity of O2 and H2O in the degradation of layered b-As under ambient
+conditions.",2207.02416v1
+2022-07-08,Copper migration and surface oxidation of $\text{Cu}_{x}\text{Bi}_2\text{Se}_3$ in ambient pressure environments,"Chemical modifications such as intercalation can be used to modify surface
+properties or to further functionalize the surface states of topological
+insulators. Using ambient pressure X-ray photoelectron spectroscopy, we report
+copper migration in $\text{Cu}_{x}\text{Bi}_2\text{Se}_3$, which occurs on a
+timescale of hours to days after initial surface cleaving. The increase in
+near-surface copper proceeds along with the oxidation of the sample surface and
+large changes in the selenium content. These complex changes are further
+modelled with core-level spectroscopy simulations, which suggest a composition
+gradient near the surface which develops with oxygen exposure. Our results shed
+light on a new phenomenon that must be considered for intercalated topological
+insulators$\unicode{x2014}$and intercalated materials in
+general$\unicode{x2014}$that surface chemical composition can change when
+specimens are exposed to ambient conditions.",2207.04155v1
+2022-07-13,$g-B_{3}C_{2}N_{3}$: A new potential two dimensional metal-free photocatalyst for overall water splitting,"In this work, using a hybrid density functional theory (DFT) based
+calculation, we propose a new two-dimensional (2D) B-C-N material,
+$g-B_{3}C_{2}N_{3}$, with the promising prospect of metal-free photocatalysis.
+A comprehensive investigation demonstrates that it is a near ultraviolet (UV)
+absorbing direct band gap (3.69 eV) semiconductor with robust dynamical and
+mechanical stability. Estimating the band positions with respect to water
+oxidation and hydrogen reduction potential levels, we observe that
+$g-B_{3}C_{2}N_{3}$ monolayer shows the possibility to be used for hydrogen
+fuel generation through spontaneous solar water splitting, over a broad pH
+range. Upon biaxial strain application the band gap decreases with increase in
+tensile strain, leading to a subsequent red shift in absorption spectra,
+implying enhanced photon harvest under solar irradiation. Furthermore, due to a
+combined effect of band gap and work function variation, biaxial strain
+realigns the band positions, allowing one to control the reducing or oxidizing
+ability as per requirement to attain environmental sustainability.",2207.06232v1
+2022-07-14,Thermal stability and optoelectronic behavior of polyaniline/GNP (graphene nanoplatelets) nanocomposites,"Polyaniline and graphene nanoplatelets (PANI-GNP) nanocomposites are
+synthesized by in situ oxidative polymerization of polyaniline using an
+oxidizing agent, ammonium peroxy disulphate (APS). The mass of GNP in the
+nanocomposites varied by 5, 10, and 15 wt% compared to PANI. The synthesized
+polyaniline coated graphene nanoplatelets (PANI-GNP) nanocomposites are
+chemically characterized and using Fourier Transform Infrared Spectroscopy
+(FTIR), Raman spectroscopy, Scanning electron microscopy (SEM), UV-Vis
+spectroscopy, and X-ray diffraction analysis (XRD). FTIR and Raman spectroscopy
+analysis confirmed the uniform coating of polyaniline on GNP. The SEM
+micrograph and XRD pattern demonstrate the polymerization quality and
+crystallization degree of samples. UV-Vis analysis showed a decrease in the
+bandgap of polyaniline, which confirms that nanocomposites are more suitable
+for optoelectronic application because of variation in the bandgap. TGA
+analysis showed the thermal stability of PANI is increased with the increased
+mass of GNP. This study suggests the potential of GNP as a filler for efficient
+modification in the morphological, electrical, optical, and thermal properties
+of PANI.",2207.07062v1
+2022-07-26,Engineering Surface Oxygen Vacancies in $\mathrm{SrTiO_3}$ to Form a High Mobility and Transparent Quasi Two dimensional Electron System,"Quasi-two-dimensional electron systems (q-2DES) are formed in various
+hetero-structures, including oxide interfaces. Oxygen vacancies (OVs) in oxides
+like $\mathrm{SrTiO_3}$ are known to produce electronic carriers. A novel way
+to produce $\mathrm{SrTiO_{3-\delta}}$ on the surface using a low-energy
+$\mathrm{H_2}$ plasma is shown here. It results in a q-2DES with mobility as
+high as $\mu \sim 20,000 \; cm^2V^{-1}s^{-1}$, displaying quantum oscillations
+in magneto-resistance. We can achieve a sharper or weaker confinement potential
+by adjusting the process pressure. The system with sharper confinement displays
+clearer quantum oscillations and Kondo-like temperature dependence of
+resistance. OVs close to the surface behaving like a correlated Anderson
+impurity is responsible for the Kondo behaviour. Quantum oscillations are less
+prominent in the weakly confined system. A cross-over from weak-localization to
+anti-localization with temperature is seen, but no Kondo behavior. The process
+also results in a transparent conductor amenable to lithographic patterning.
+This conductor's standard figure of merit is comparable to poly-crystalline ITO
+films in the visible regime and extends with similar performance into the
+$\lambda$ $\sim 1.5$ $\mu m$ telecommunication wavelength.",2207.12933v1
+2022-07-28,Polaronic Optical Transitions in Hematite ($α-Fe_{2}O_{3}$) Revealed by First-Principles Electron-Phonon Coupling,"Polaron formation following optical absorption is a key process that defines
+the photophysical properties of many semiconducting transition metal oxides,
+which comprise an important class of materials with potential optoelectronic
+and photocatalytic applications. In this work, we use hematite
+(${\alpha}-Fe_{2}O_{3}$) as a model transition metal oxide semiconductor to
+demonstrate the feasibility of direct optical population of band-edge polaronic
+states. We employ first-principles electron-phonon computations within the
+framework of the DFT+U+J method to reveal the presence of these states within a
+thermal distribution of phonon displacements and model their evolution with
+temperature. Our computations reproduce the temperature dependence of the
+optical dielectric function of hematite with remarkable accuracy and indicate
+that the band-edge optical absorption and second-order resonance Raman spectra
+arise from polaronic optical transitions involving coupling to longitudinal
+optical phonons with energies greater than 50 meV. Additionally, we find that
+the resulting polaron comprises an electron localized to two adjacent Fe atoms
+with distortions that lie primarily along the coordinates of phonons with
+energies of 31 and 81 meV.",2207.14184v1
+2022-07-28,What X-ray absorption spectroscopy can tell us about the active state of earth-abundant electrocatalysts for the oxygen evolution reaction,"Chemical energy storage is an attractive solution to secure a sustainable
+energy supply. It requires an electrocatalyst to be implemented efficiently. In
+order to rationally improve the electrocatalyst materials and thereby the
+reaction efficiency, one must reveal the nature of the electrocatalyst under
+reaction conditions, i.e., its active state. For a better understanding of
+earth-abundant metal oxides as electrocatalysts for the oxygen evolution
+reaction (OER), the combination of electrochemical (EC) methods and X-ray
+absorption spectroscopy (XAS) has been very insightful and still holds untapped
+potential. Herein, we concisely introduce the basics of EC and XAS and provide
+the necessary framework to discuss changes that electrocatalytic materials
+undergo, presenting manganese oxides as examples. Such changes may occur during
+preparation and storage, during immersion in an electrolyte, as well as during
+application of potentials without or with catalytic reactions. We conclude with
+a concise summary of how EC and XAS are currently combined to elucidate the
+active state as well as an outlook on future opportunities to understand the
+mechanisms of electrocatalysis using combined operando EC-XAS experiments.",2207.14360v1
+2022-07-29,Low-frequency Phonon at Perovskite Oxide Interface Studied by Surface-specific Nonlinear Terahertz Spectroscopy,"The low-frequency collective excitations, which often occur in the terahertz
+or multi-terahertz spectral region, play an essential role in many novel
+emergent phenomena. Despite numerous studies in the bulk, detection of such
+excitations at interfaces remains challenging owing to the lack of feasible
+experimental techniques. Here, we show that interfacial low-frequency modes can
+be characterized using surface-specific nonlinear terahertz spectroscopy. This
+technique uses intra-pulse difference frequency mixing (DFM) process that can
+extend the second-order optical spectroscopy to the terahertz range. As a
+demonstration, the surface phonon of SrTiO3(001) at 2.8 THz was successfully
+measured. This surface polarization originates from the excess of oxygen
+vacancies or charge transfer at the interface. We have also developed an
+analytical procedure for remote measurement of the interfacial potential of
+complex oxides in a practical environment. Our method offers new opportunities
+for in situ studies of the low-frequency excitations at interfaces in broad
+disciplines.",2207.14610v1
+2022-08-03,Detection of High Energy Ionizing Radiation using Deeply Depleted Graphene-Oxide-Semiconductor Junctions,"Graphene's linear bandstructure and two-dimensional density of states provide
+an implicit advantage for sensing charge. Here, these advantages are leveraged
+in a deeply depleted graphene-oxide-semiconductor (D2GOS) junction detector
+architecture to sense carriers created by ionizing radiation. Specifically, the
+room temperature response of the silicon-based D2GOS junction is analyzed
+during irradiation with 20 MeV Si4+ ions. Detection was demonstrated for doses
+ranging from 12-1200 ions with device functionality maintained with no
+substantive degradation. To understand the device response, D2GOS pixels were
+characterized post-irradiation via a combination of electrical
+characterization, Raman spectroscopy, and photocurrent mapping. This combined
+characterization methodology underscores the lack of discernible damage caused
+by irradiation to the graphene while highlighting the nature of interactions
+between the incident ions and the silicon absorber.",2208.02366v1
+2022-08-06,Tunable two-dimensional superconductivity and spin-orbit coupling at the EuO/KTaO3(110) interface,"Unconventional quantum states, most notably the two-dimensional (2D)
+superconductivity, have been realized at the interfaces of oxide
+heterostructures where they can be effectively tuned by the gate voltage
+($V_G$). Here we report that the interface between high-quality EuO (111) thin
+film and KTaO3 (KTO) (110) substrate shows superconductivity with onset
+transition temperature $T_c^{onset}$ = 1.35 K. The 2D nature of
+superconductivity is verified by the large anisotropy of the upper critical
+field and the characteristics of a Berezinskii-Kosterlitz-Thouless transition.
+By applying $V_G$, $T_c^{onset}$ can be tuned from ~ 1 to 1.7 K; such an
+enhancement can be possibly associated with a boosted spin-orbit energy
+${\epsilon}_{so}$ = $\hbar$ / ${\tau}_{so}$, where ${\tau}_{so}$ is the
+spin-orbit relaxation time. Further analysis of ${\tau}_{so}$ based on the
+upper critical field ($H_{c2}$) and magnetoconductance reveals complex nature
+of spin-orbit coupling (SOC) at the EuO/KTO(110) interface with different
+mechanisms dominate the influence of SOC effects for the superconductivity and
+the magnetotransport in the normal state. Our results demonstrate that the SOC
+should be considered as an important factor determining the 2D
+superconductivity at oxide interfaces.",2208.03507v1
+2022-08-18,Thermally Oxidized MoS$_2$-Based Hybrids as Superior Electrodes for Supercapacitor and Photoelectrochemical Applications,"High electronic transport and reasonable chemical stability of molybdenum
+disulfide (MoS$_2$) make it very suitable for electrochemical applications.
+However, its energy storage capacity is still low compared with other
+nanostructures. In this work, pristine and thermally oxidized MoS$_2$
+(O@MoS$_2$) based hybrids are introduced by a simple method with enhanced
+capacitive performance thanks to the contribution of synergistic effects.
+Scanning electron microscopy (SEM), Transmission electron microscopy (TEM),
+X-ray diffraction (XRD), elemental mapping, UV-Visible, and Raman analyses are
+employed to investigate the morphological and crystalline structure of the
+introduced hybrids. In detail, the highest gravimetric capacitance of ~205.1
+Fg-1 is achieved for the MoS$_2$:O@MoS$_2$ hybrid with a mass ratio of 2:1
+compared to pristine and other electrodes. This electrode is also accompanied
+by the longest discharging time and excellent cyclic stability of ~%113 after
+2000 continuous charge-discharge cycles. In addition, photoelectrochemical
+testing of the introduced electrode leads to a ~63% increase in carrier
+photogeneration compared to MoS$_2$ due to the effective charge separation
+within the hybrid, which makes it suitable for water splitting and hydrogen
+production applications.",2208.08799v1
+2022-08-24,Numerical analysis of dilute methanol spray flames in vitiated coflow using extended Flamelet Generated Manifold model,"The present work focuses on the large eddy simulation (LES) and the study of
+turbulent dilute methanol spray flames in vitiated coflow using the secondary
+oxidizer Flamelet Generated Model (FGM). The modified FGM model uses an
+additional secondary oxidizer parameter in addition to the three other
+parameters previously used for spray flames progress variable, mixture
+fraction, and enthalpy. The results for gas phase and droplet properties are
+validated against the dilute methanol spray flame database for varying fuel
+injection amounts. The droplet statistics and the lift-off flame heights are
+accurately captured for all the cases. A proper orthogonal decomposition (POD)
+of the scalar fluctuating hydroxyl radical (OH) field and velocity-temperature
+field capture the flame structures in the downstream region of ignition
+kernels. The detailed POD analysis reveals that the base frequency of the
+dominant OH field equals that of the dominant vortical structure of 67.3 Hz.
+The flame propagation happens around these dominant vortical structures because
+of the less-strained fluid mixing.",2208.11554v1
+2022-08-29,Structure and transport properties of poly(ethylene oxide) based cross-linked polymer electrolytes -- A Molecular Dynamics Simulations study,"We present an extensive molecular dynamics (MD) simulation study of
+poly(ethylene oxide) (PEO) based densely cross-linked polymers, focussing on
+structural properties as well as the systems dynamics in the presence of
+lithium salt. Motivated by experimental findings for networks with short PEO
+strands we employ a combination of LiTFSI (Lithium
+bis(trifluoromethanesulfonyl)imide) and LiDFOB (Lithium
+difluoro(oxalato)borate). Recently, it has been shown that such multi-salt
+systems outperform classical single salt systems (Shaji et al., Energy Storage
+Materials, 2022, 44, 263). To analyse the microscopic scenario we employ an
+analytical model, originally developed for non-cross-linked polymer
+electrolytes or blends (Maitra et al., Phys. Rev. Lett., 2007, 98, 227802 and
+Diddens et al., J. Electrochem. Soc., 2017, 164, E3225-E3231). Excluding very
+short PEO strands, the local dynamics is only slightly restricted compared to
+linear PEO and is not significantly dependent on the network structure. The
+transfer of lithium ions between PEO chains and the motion along the polymer
+backbone may be controlled through the employed salt.",2208.13450v1
+2022-08-29,Machine Learning guided high-throughput search of non-oxide garnets,"Garnets, known since the early stages of human civilization, have found
+important applications in modern technologies including magnetorestriction,
+spintronics, lithium batteries, etc. The overwhelming majority of
+experimentally known garnets are oxides, while explorations (experimental or
+theoretical) for the rest of the chemical space have been limited in scope. A
+key issue is that the garnet structure has a large primitive unit cell,
+requiring an enormous amount of computational resources. To perform a
+comprehensive search of the complete chemical space for new garnets,we combine
+recent progress in graph neural networks with high-throughput calculations. We
+apply the machine learning model to identify the potential (meta-)stable garnet
+systems before systematic density-functional calculations to validate the
+predictions. In this way, we discover more than 600 ternary garnets with
+distances to the convex hull below 100~meV/atom with a variety of physical and
+chemical properties. This includes sulfide, nitride and halide garnets. For
+these, we analyze the electronic structure and discuss the connection between
+the value of the electronic band gap and charge balance.",2208.13742v1
+2022-09-01,From High-Entropy Ceramics (HECs) to Compositionally Complex Ceramics (CCCs),"This invited talk will review a series of our recent studies on high-entropy
+ceramics (HECs) and compositionally complex ceramics (CCCs) and discuss the
+future perspective. Various single-phase equimolar quinary (five-component)
+HECs, e.g., MB2, MB, M3B4, MB4, and MB6 borides, MSi2 and M3Si5 silicides,
+perovskite, fluorite, and pyrochlore oxides, and (intermetallic) aluminides
+have been fabricated. We further proposed to extend HECs to CCCs to include
+non-equimolar compositions and further consider short- and long-range orders,
+which reduce configurational entropies but offer additional dimensions and
+opportunities to tailor and improve various properties. We also reported the
+first dual-phase HECs/CCCs. Using compositionally complex fluorite-based oxides
+(CCFBOs, which can possess fluorite or defect fluorite, pyrochlore, weberite,
+fergusonite, and bixbyite phases) as the model systems, we have recently
+discovered long- and short- range orders, composition- and redox-induced
+order-disorder transitions (ODTs), and ultrahigh-entropy weberite and
+fergusonite phases in several 10- to 21-component systems.",2209.00752v1
+2022-09-09,Flexo-photovoltaic effect and above-bandgap photovoltage in halide perovskites,"Halide perovskites have outstanding photovoltaic properties which have been
+optimized through interfacial engineering. However, as these materials approach
+the limits imposed by the physics of semiconductor junctions, it is urgent to
+explore alternatives, such as the bulk photovoltaic effect, whose physical
+origin is different and not bound by the same limits. In this context, we focus
+on the flexo-photovoltaic effect, a type of bulk photovoltaic effect that was
+recently observed in oxides under strain gradients. We have measured the
+flexo-photovoltaic effect of MAPbBr3 and MAPbI3 crystals under bending and
+found it to be orders of magnitude larger than for SrTiO3, the benchmark
+flexo-photovoltaic oxide. For sufficiently large strain gradients,
+photovoltages bigger than the bandgap can be produced. Bulk photovoltaic
+effects are additive and, for MAPbI3, the flexo-photovoltage exists on top of a
+native bulk photovoltage that is hysteretic, consistent with the electrically
+switchable macroscopic polarization of this material. The results suggest that
+harnessing the flexo-photovoltaic effect through strain gradient engineering
+can provide a functional leap forward for halide perovskites.",2209.04277v3
+2022-09-13,Gaussian-Based Quasiparticle Self-Consistent $GW$ for Periodic Systems,"We present a quasiparticle self-consistent $GW$ (QSGW) implementation for
+periodic systems based on crystalline Gaussian basis sets. Our QSGW approach is
+based on a full-frequency analytic continuation GW scheme with Brillouin zone
+sampling and employs the Gaussian density fitting technique. We benchmark our
+QSGW implementation on a set of weakly-correlated semiconductors and insulators
+as well as strongly correlated transition metal oxides including MnO, FeO, CoO,
+and NiO. Band gap, band structure, and density of states are evaluated using
+finite size corrected QSGW. We find that although QSGW systematically
+overestimates band gaps of tested semiconductors and transition metal oxides,
+it completely removes the dependence on the choice of density functionals and
+provides more consistent prediction of spectral properties than $G_0W_0$ across
+a wide range of solids. This work paves the way for utilizing QSGW in ab initio
+quantum embedding for solids.",2209.06179v2
+2022-09-19,Effect of Pore Formation on Redox-Driven Phase Transformation,"When solid-state redox-driven phase transformations are associated with mass
+loss, vacancies are produced that develop into pores. These pores can influence
+the kinetics of certain redox and phase transformation steps. We investigated
+the structural and chemical mechanisms in and at pores in a combined
+experimental-theoretical study, using the reduction of iron oxide by hydrogen
+as a model system. The redox product (water) accumulates inside the pores and
+shifts the local equilibrium at the already reduced material back towards
+re-oxidation into cubic-Fe1-xO (where x refers to Fe deficiency, space group
+Fm3-m). This effect helps to understand the sluggish reduction of cubic-Fe1-xO
+by hydrogen, a key process for future sustainable steelmaking.",2209.09069v2
+2022-09-20,Characteristics of a Nickel Vanadium redox flow battery Based on COMSOL,"The overpotential, dissociation rate, electrode potential distributions and
+current density are suggested in this study to analyze the Nickel Vanadium
+Redox Flow Battery (NVRFB). Due to its large capacity and ecofriendly
+properties, NVRFB may be a viable option in the present state of energy
+constraint and environmental pollution. Due to their low cost and high energy
+density, nickel-based flow batteries have gained popularity. This study
+demonstrates that the Ni2+/Ni+ and V5+/V4+ ions have a higher rate of
+dissociation at the membrane and a lower rate at the inlet, where the
+electrolyte flow velocity is greater; Because the membrane undergoes more
+oxidation-reduction reactions, the electrolyte flow rate is critical in the
+redox flow cell; Additionally, we see that when electrode thickness is reduced,
+current density and electrode potential increase while overpotential decreases;
+the model's equations are solved using the finite-element method in the COMSOL
+Multiphysics program. An electrolyte-electrode interface connection is used to
+simulate the reaction. The dissociation rate indicates that the
+oxidation-reduction process happens at a lower membrane potential. Improving
+the electrolyte flow rate enhances battery performance. Compression of the
+electrodes enhances conductivity and battery performance.",2209.09872v1
+2022-09-28,Evolution of electronic band reconstruction in thickness-controlled perovskite SrRuO$_3$ thin films,"Transition metal perovskite oxides display a variety of emergent phenomena
+which are tunable by tailoring the oxygen octahedral rotation. SrRuO$_3$, a
+ferromagnetic perovskite oxide, is well-known to have various atomic structures
+and octahedral rotations when grown as thin films. However, how the electronic
+structure changes with the film thickness has been hardly studied. Here, by
+using angle-resolved photoemission spectroscopy and electron diffraction
+techniques, we study the electronic structure of SrRuO$_3$ thin films as a
+function of the film thickness. Different reconstructed electronic structures
+and spectral weights are observed for films with various thicknesses. We
+suggest that octahedral rotations on the surface can be qualitatively estimated
+via comparison of intensities of different bands. Our observation and
+methodology shed light on how structural variation and transition may be
+understood in terms of photoemission spectroscopy data.",2209.13813v1
+2022-10-02,Nonlinear optical birefringence in Li2SO4-MgO-P2O5 amorphous system-influence of Cu ions,"Li2SO4-MgO-P2O5 glasses doped with varied contents of CuO (from 0- 1.0 mol%)
+were prepared. The optical birefringence induced by a High Q-2 femtosecond
+pulsed laser is explored as a function of copper oxide concentration in these
+glasses. The magnitude of the light-induced birefringence exhibited a gradual
+decrease with the increase of copper oxide content. The observed behavior is
+discussed in terms of polymerization of the glass network, the degree of which
+rises with concentration of Cu+ ions occupying Td sites in the glass matrix.
+However, the samples containing low content of CuO are dominated by Cu2+ ions
+that act as modifiers and induce structural imperfections by breaking of P-O-S
+bonds. Accordingly, the samples mixed with lower content of CuO are more
+favorable for inducing higher magnitudes of the optical birefringence. This
+conclusion is corroborated by results of electrical conductivity, positron
+annihilation and ultrasonic measurements.",2210.00404v1
+2022-10-04,Atomic Level Strain Induced by Static and Dynamic Oxygen Vacancies on Reducible Oxide Surfaces,"Surface strain often controls properties of the material including charge
+transport and chemical reactivity. Localized surface strain is measured with
+atomic resolution on (111) ceria nanoparticle surfaces using environmental
+transmission electron microscopy under different redox conditions. Density
+Functional Theory (DFT) coupled with TEM image simulations have been used for
+aid in interpreting the experimental data. Oxygen vacancy creation/annihilation
+introduces strain at surface and near surface regions on cation sublattice.
+Static and fluxional strainmaps are generated from images at these different
+conditions and compared. While fluxional strain is highest at locations
+associated with unstable vacancies at active sites, highly inhomogeneous static
+strain fields comprising of alternating tensile/compressing strain is seen at
+surface and subsurfaces linked to the presence of stable oxygen vacancies.
+Interestingly, both stable and unstable oxygen vacancies are found within a few
+atomic spacing of each other on the same surface. The static strain pattern
+depends on the ambient inside TEM. Oxidizing environments tend to lower vacancy
+concentrations at the surface whereas a highly reducing environment created
+using high electron dose creates oxygen vacancies everywhere (bulk and
+surfaces) in the nanoparticle.",2210.01764v2
+2022-10-05,A quantum spin liquid phase in the Kitaev-Hubbard model,"The quantum spin liquid (QSL) state has been searched intensively in
+Kitaev-like materials, such as the Iridium oxides $A_2$IrO$_3$ and
+$\alpha$-RuCl$_3$. The half-filled Kitaev-Hubbard model with bond dependent
+hopping terms is used to describe the Kitaev-like materials, which is
+calculated using the state-of-the-art fermionic projected entangled pair states
+(fPEPS) method. We find a QSL phase near the Mott insulator transition, which
+has a strong first-order transition to the semi-metal phase with the decrease
+of Hubbard $U$. We suggest that a promising routine to find the QSL is to find
+the Iridium oxides that are near the Mott insulator transitions.",2210.01996v1
+2022-10-28,Highly-Excited Rydberg Excitons in Synthetic Thin-Film Cuprous Oxide,"Cuprous oxide (Cu${}_2$O) has recently been proposed as a promising
+solid-state host for excitonic Rydberg states with large principal quantum
+numbers ($n$), whose exaggerated wavefunction sizes ($\propto n^2)$ facilitate
+gigantic dipole-dipole ($\propto n^4$) and van der Waals ($\propto n^{11}$)
+interactions, making them an ideal basis for solid-state quantum technology.
+Synthetic, thin-film Cu${}_2$O samples are of particular interest because they
+can be made defect-free via carefully controlled fabrication and are, in
+principle, suitable for the observation of extreme single-photon nonlinearities
+caused by the Rydberg blockade. Here, we present spectroscopic absorption and
+photoluminescence studies of Rydberg excitons in synthetic Cu${}_2$O grown on a
+transparent substrate, reporting yellow exciton series up to $n = 7$. We
+perform these studies at powers up to 2 mW and temperatures up to 150 K, the
+highest temperature where Rydberg series can be observed. These results open a
+new portal to scalable and integrable on-chip Rydberg-based quantum devices.",2210.16416v1
+2022-11-05,Photo-thermal tuning of graphene oxide coated integrated optical waveguides,"We experimentally investigate power sensitive photothermal tuning (PTT) of
+two dimensional (2D) graphene oxide (GO) films coated on integrated optical
+waveguides. We measure the light power thresholds for reversible and permanent
+GO reduction in silicon nitride (SiN) waveguides integrated with 1 and 2 layers
+of GO. Raman spectra at different positions of a hybrid waveguide with
+permanently reduced GO are characterized, verifying the inhomogeneous GO
+reduction along the direction of light propagation through the waveguide. The
+differences between the PTT induced by a continuous wave laser and a pulsed
+laser are also compared, confirming that the PTT mainly depend on the average
+input power. These results reveal interesting features for 2D GO films coated
+on integrated optical waveguides, which are of fundamental importance for the
+control and engineering of GO properties in hybrid integrated photonic devices.",2211.02983v1
+2022-11-11,Reverse Doping Asymmetry in Semiconductor Thin Films Using External Voltage,"Doping asymmetry is a notable phenomenon with semiconductors and a
+particularly longstanding challenge limiting the applications of most
+wide-band-gap semiconductors, which are inherent of spontaneous heavy n- or
+p-type doping because of their extreme band edges. This study theoretically
+shows that by applying a proper external voltage on materials during their
+growth or doping processes, we can largely tune the band edges and consequently
+reverse the doping asymmetry in semiconductor thin films. We take zinc oxide as
+a touchstone and computationally demonstrate that this voltage-assisted-doping
+approach efficiently suppresses the spontaneous n-type defects by around four
+orders under three distinct growth conditions and successfully generates p-type
+zinc oxide up to the lowest acceptor levels. The proposed approach is
+insensitive to materials, growth conditions, or defects origins, and thus
+offers a general solution to the doping asymmetry in semiconductor thin films.",2211.05990v2
+2022-11-14,"Insight into the effect of rare earth $RE=Ce,\; Nd,\; Gd$ elements on the physical properties of Pb-Based Pervoskite Oxides ($PbREO_3$)","The electronic, elastic, structural, thermoelectric and optical parameters of
+the Pb-based cubic perovskites $PbREO_3\; (RE=Ce,\; Gd,\; Nd)$ were calculated
+using the WIEN2k Package. The mechanical optimization and structural
+stabilities were evaluated. The found results are in full agreement with the
+experimental ones. The obtained elastic results show that these perovskites
+behave as stable ductile materials, and their higher $Y$ value gives them a
+rigid structures. The $PbCeO_3$ presents n-type semiconductor while $PbREO_3\;
+(RE= Gd,\; Nd)$ exhibit p-type semi-conductor with gap energies of $2.60\;eV$,
+$1.02\;eV$ and $1.55\;eV$, respectively. The optical properties show that
+$PbREO_3\; (RE=Ce,\; Gd,\; Nd)$ have significant absorption in the visible
+light region with low reflectivity. The thermoelectric properties present a
+desired electrical performance at room temperature for all materials. For these
+generation of materials the effect of RE on Pb-based cubic perovskite oxides
+can be exploited in manufacturing of thermoelectric, mechanic and
+optoelectronic devices.",2211.07221v1
+2022-11-22,Semi-supervised generative approach to point-defect formation in chemically disordered compounds: application to uranium-plutonium mixed oxides,"Machine-learning methods are nowadays of common use in the field of material
+science. For example, they can aid in optimizing the physicochemical properties
+of new materials, or help in the characterization of highly complex chemical
+compounds. An especially challenging problem arises in the modeling of
+chemically disordered solid solutions, for which some properties depend on the
+distribution of chemical species in the crystal lattice. This is the case of
+defect properties of uranium-plutonium mixed oxides nuclear fuels. The number
+of possible configurations is so high that the problem becomes intractable if
+treated with direct sampling. We thus propose a machine learning approach,
+based on generative modeling, to optimize the exploration of this large
+configuration space. A probabilistic, semi-supervised approach using Mixture
+Density Network is applied to estimate the concentration of thermal defects in
+(U, Pu)O2. We show that this method, based on the prediction of the density of
+states of formation energy of a defect, is computationally much more
+cost-efficient compared to other approaches available in the literature.",2211.12086v2
+2022-12-03,Microstructure Evolution of Solid Oxide Fuel Cell Anodes Characterized by Persistent Homology,"Uncovering microstructure evolution mechanisms that accompany the long-term
+operation of solid oxide fuel cells is a fundamental challenge in designing a
+more durable energy system for the future. To date, the study of fuel cell
+stack degradation has focused mainly on electrochemical performance and, more
+rarely, on averaged microstructural parameters. Here we show an alternative
+approach in which an evolution of three-dimensional microstructural features is
+studied using electron tomography coupled with topological data analysis. The
+latter produces persistent images of microstructure before and after long-term
+operation of electrodes. Those images unveil a new insight into the degradation
+process of three involved phases: nickel, pores, and yttrium-stabilized
+zirconium.",2212.01576v1
+2022-12-05,Discovery of a metallic oxide with ultralow thermal conductivity,"A compound with metallic electrical conductivity usually has a considerable
+total thermal conductivity because both electrons and photons contribute to
+thermal transport. Here, we show an exceptional example of iridium oxide,
+Bi3Ir3O11, that concurrently displays metallic electrical conductivity and
+ultralow thermal conductivity approaching 0.61 W m-1 K-1 at 300 K. The compound
+crystallizes into a cubic structural framework with space group Pn-3. The edge-
+and corner-sharing IrO6 octahedra with a mixed Ir4.33+ charge state favor
+metallic electrical transport. Bi3Ir3O11 exhibits an extremely low lattice
+thermal conductivity close to the minimum limit in theory owing to its
+tunnel-like structure with filled heavy atoms Bi rattling inside. Theoretical
+calculations reveal the underlying mechanisms for the extraordinary
+compatibility between metallic electrical conductivity and ultralow thermal
+conductivity. This study may establish a new avenue for designing and
+developing unprecedented heat-insulation metals.",2212.02040v1
+2022-12-15,Nd:YAG single crystals grown by floating zone method in laser furnace,"We report on single crystal growth of laser material Nd:YAG widely used in
+the applications by innovative crucible-free floating zone method implemented
+in an advanced laser optical furnace. We have optimized the parameters for the
+production of high-quality single crystals of the size typical for laser tubes.
+To reduce the strain and improve machinability, we have developed an
+afterheater to thermalize the grown part of a single crystal below the hot
+zone, which is a technique unavailable in common mirror furnaces. The high
+quality of the single crystals was verified by Laue diffraction and the
+internal strain was documented by neutron diffraction. The absorption spectrum
+corresponds with the parameters of the commercially used material produced by
+Czochralski method. The presented methodology for the single crystal growth by
+floating zone method with laser heating is applicable for the preparation of
+other high-quality single crystals of oxide-based materials, particularly in an
+oxidizing environment unattainable in commonly used crucible methods.",2212.07662v1
+2022-12-16,Reduced ITO for Transparent Superconducting Electronics,"Absorption of light in superconducting electronics is a major limitation on
+the quality of circuit architectures that integrate optical components with
+superconducting components. A 10 nm thick film of a typical superconducting
+material like niobium can absorb over half of any incident optical radiation.
+We propose instead using superconductors which are transparent to the
+wavelengths used elsewhere in the system. In this paper we investigated reduced
+indium tin oxide (ITO) as a potential transparent superconductor for
+electronics. We fabricated and characterized superconducting wires of reduced
+indium tin oxide. We also showed that a $\SI{10}{nm}$ thick film of the
+material would only absorb about 1 - 20\% of light between 500 - 1700 nm.",2212.08573v1
+2023-01-02,Thermo-optic phase shifter based on hydrogen-doped indium oxide microheater,"Thermo-optic (TO) phase shifters are very fundamental units in large-scale
+active silicon photonic integrated circuits (PICs). However, due to the
+limitation of microheater materials with a trade-off between heating efficiency
+and absorption loss, designs reported so far typically suffer from slow
+response time, high power consumption, low yields, and so on. Here, we
+demonstrate an energy-efficient, fast-response, and low-loss TO phase shifter
+by introducing hydrogen-doped indium oxide (IHO) films as microheater, and the
+optimized electron concentration with enhanced mobility endows the IHO high
+conductivity as well as high near-infrared (NIR) transparency, which allow it
+to directly contact the silicon waveguide without any insulating layer for
+efficient tuning and fast response. The TO phase shifter achieves a
+sub-microsecond response time (970 ns/980 ns) with a {\pi} phase shift power
+consumption of 9.6 mW. And the insertion loss introduced by the IHO microheater
+is ~ 0.5 dB. The proposed IHO-based microheaters with compatible processing
+technology illustrate the great potential of such material in the application
+of large-scale silicon PICs.",2301.00816v1
+2023-01-05,Review: Graphene oxide 2D thin films for high performance nonlinear integrated photonics,"Integrated photonic devices operating via optical nonlinearities offer a
+powerful solution for all optical information processing, yielding processing
+speeds that are well beyond that of electronic processing as well as providing
+the added benefits of compact footprint, high stability, high scalability, and
+small power consumption. The increasing demand for high performance nonlinear
+integrated photonic devices has facilitated the hybrid integration of novel
+materials to address the limitations of existing integrated photonic platforms,
+such as strong nonlinear optical absorption or an inadequate optical
+nonlinearity. Recently, graphene oxide (GO), with its large optical
+nonlinearity, high flexibility in altering its properties, and facile
+fabrication processes, has attracted significant attention, enabling many
+hybrid nonlinear integrated photonic devices with improved performance and
+novel capabilities. This paper reviews the applications of GO to nonlinear
+integrated photonics. First, an overview of GOs optical properties and the
+fabrication technologies needed for its onchip integration is provided. Next,
+the state of the art GO nonlinear integrated photonic devices are reviewed,
+together with comparisons of the nonlinear optical performance of different
+integrated platforms incorporating GO. Finally, the challenges and perspectives
+of this field are discussed.",2301.01862v1
+2023-01-09,How do Quantum Effects Influence the Capacitance and Carrier Density of Monolayer MoS$_2$ Transistors?,"When transistor gate insulators have nanometer-scale equivalent oxide
+thickness (EOT), the gate capacitance ($C_\textrm{G}$) becomes smaller than the
+oxide capacitance ($C_\textrm{ox}$) due to the quantum capacitance and charge
+centroid capacitance of the channel. Here, we study the capacitance of
+monolayer MoS$_\textrm{2}$ as a prototypical two-dimensional (2D) channel while
+considering spatial variations in the potential, charge density, and density of
+states. At 0.5 nm EOT, the monolayer MoS$_\textrm{2}$ capacitance is smaller
+than its quantum capacitance, limiting the single-gated $C_\textrm{G}$ of an
+n-type channel to between 63% and 78% of $C_\textrm{ox}$ for gate overdrive
+voltages between 0.5 and 1 V. Despite these limitations, for dual-gated
+devices, the on-state $C_\textrm{G}$ of monolayer MoS$_\textrm{2}$ is 50%
+greater than that of silicon at 0.5 nm EOT and more than three times that of
+InGaAs at 1 nm EOT, indicating that 2D semiconductors are promising for
+nanoscale devices at future technology nodes.",2301.03453v2
+2023-01-12,Diagnostics for plasmon satellites and Hubbard bands in transition metal oxides,"Coulomb correlations between the electrons imprint characteristic signatures
+to the spectral properties of materials. Among others, they are at the origin
+of a rich phenomenology of satellite features, either stemming from atomic-like
+multiplets or from interactions with particle-hole excitations or plasmons.
+While in many cases the latter lie at considerably higher energies than the
+former, suggesting clear distinction criteria, this picture has recently become
+blurred by indications that satellites of different types can coexist in the
+same energy range. It is now generally accepted that the identification of the
+nature of spectral features is a highly non-trivial task. In this article we
+propose a general procedure for tracing the origin of satellites of different
+types within modern ab initio calculations. As an illustration, we analyze the
+ternary transition metal oxides SrVO$_3$ and SrMoO$_3$, which are drosophila
+compounds for the coexistence of Hubbard and plasmonic satellites, reconciling
+previous seemingly contradictory findings in an unexpected manner.",2301.04908v1
+2023-01-07,Significant CO2 photoreduction on a high-entropy oxynitride,"CO$_2$ photoreduction on photocatalysts is a nature-friendly solution to
+decrease the CO$_2$ amount, but the method still has low efficiency because of
+difficult separation and easy recombination of charge carriers in available
+catalysts. In this study, a high-entropy oxynitride was introduced as an active
+photocatalyst for photoreduction. The material had a chemical composition of
+TiZrNbHfTaO$_6$N$_3$ and was produced by a high-pressure torsion method
+followed by oxidation and nitriding. It showed higher photocatalytic CO$_2$ to
+CO conversion compared to corresponding high-entropy oxide, benchmark
+photocatalyst P25 TiO$_2$, and almost all catalysts introduced in the
+literature. The high activity of this oxynitride, which also showed good
+chemical stability, was attributed to the large absorbance of light and easy
+separation of electrons and holes, the low recombination of charge carriers,
+and the high CO$_2$ adsorption on the surface. These findings introduce
+high-entropy oxynitrides as promising photocatalysts for CO$_2$ photoreduction.",2301.05013v2
+2023-01-12,Surface acoustic wave generation and detection in quantum paraelectric regime of SrTiO$_3$-based heterostructure,"Strontium titanate (STO), apart from being a ubiquitous substrate for
+complex-oxide heterostructures, possesses a multitude of strongly-coupled
+electronic and mechanical properties. Surface acoustic wave (SAW) generation
+and detection offers insight into electromechanical couplings that are
+sensitive to quantum paraelectricity and other structural phase transitions.
+Propagating SAWs can interact with STO-based electronic nanostructures, in
+particular LaAlO$_3$/SrTiO$_3$ (LAO/STO). Here we report generation and
+detection of SAW within LAO/STO heterointerfaces at cryogenic temperatures
+($T\ge$~2 K) using superconducting interdigitated transducers (IDTs). The
+temperature dependence shows an increase in the SAWs quality factor that
+saturates at $T\approx 8 $ K. The effect of backgate tuning on the SAW
+resonance frequency shows the possible acoustic coupling with the ferroelastic
+domain wall evolution. This method of generating SAWs provides a pathway
+towards dynamic tuning of ferroelastic domain structures, which are expected to
+influence electronic properties of complex-oxide nanostructures. Devices which
+incorporate SAWs may in turn help to elucidate the role of ferroelastic domain
+structures in mediating electronic behavior.",2301.05324v1
+2023-01-18,Evolution of orbital excitations from insulating to superconducting MgTi$_2$O$_4$ films,"Spinel oxides are well-known functional materials but rarely show
+superconductivity. Recently, emergent superconductivity was discovered in
+MgTi$_2$O$_4$, which is attributed to the increase of electron doping and the
+suppression of orbital order. Here, we utilized Ti $L$-edge resonant inelastic
+X-ray scattering to study the orbital excitations in superconducting (SC) and
+insulating MgTi$_2$O$_4$ films. We find that the spectral weight of orbital
+excitations is enhanced and the energy of $t_{2g}$ intra-band excitation is
+softened in the SC film compared to the insulating one, suggesting higher
+electron doping and suppressed orbital order gap in the SC sample. These
+observations were further supported by our multiplet calculations using minimal
+two-site model. Our results provide spectroscopic evidence for the competition
+between orbital order and superconductivity in MgTi$_2$O$_4$ and shed light on
+searching for novel superconductors in spinel oxides.",2301.07299v1
+2023-01-24,Accurate Energy Barriers for Catalytic Reaction Pathways: An Automatic Training Protocol for Machine Learning Force Fields,"In this study, we introduce a training protocol for developing machine
+learning force fields (MLFFs), capable of accurately determining energy
+barriers in catalytic reaction pathways. The protocol is validated on the
+extensively explored hydrogenation of carbon dioxide to methanol over indium
+oxide. With the help of active learning, the final force field obtains energy
+barriers within 0.05 eV of Density Functional Theory. Thanks to the
+computational speedup, not only do we reduce the cost of routine in-silico
+catalytic tasks, but also find a 40\% reduction in the previously established
+rate-limiting step. Furthermore, we illustrate the importance of
+finite-temperature effects and compute free energy barriers. The
+transferability of the protocol is demonstrated on the experimentally relevant,
+yet unexplored, top-layer reduced indium oxide surface. The ability of MLFFs to
+enhance our understanding of extensively studied catalysts underscores the need
+for fast and accurate alternatives to direct ab-intio simulations.",2301.09931v2
+2023-01-29,Interaction of oxygen with pristine and defective MoS2 monolayers,"Atom controlled sub-nanometer MoS$_2$ pores have been recently fabricated.
+Oxidative environments are of particular interest for MoS$_2$ applications in
+electronics, sensing and energy storage. In this work we carried out
+first-principles calculations of oxygen adsorption in plain and sub-nanometer
+MoS$_2$ nanopores. The chemical stability of the layers and pores towards
+oxygen was verified using density-functional theory. Dissociation and diffusion
+barriers have been calculated in order to understand surface and pore oxidation
+and its electronic properties at the atomic scale, which opens the path for
+future investigations of MoS$_2$ pores in a realistic environment.",2301.12337v1
+2023-01-30,Growth of $α-Ga_2O_3$ on $Al_2O_3$ by conventional molecular-beam epitaxy and metal-oxide-catalyzed epitaxy,"We report the growth of $\alpha-Ga_2O_3$ on $m$-plane $Al_2O_3$ by
+conventional plasma-assisted molecular-beam epitaxy (MBE) and In-mediated
+metal-oxide-catalyzed epitaxy (MOCATAXY). We report a growth-rate-diagram for
+$\alpha-Ga_2O_3$ (10-10), and observe (i) a growth rate increase, (ii) an
+expanded growth window, and (iii) reduced out-of-lane mosaic spread when
+MOCATAXY is employed for the growth of $\alpha-Ga_2O_3$. Through the use of
+In-mediated catalysis, growth rates over $0.2\,\mu\text{m}\,\text{hr}^{-1}$ and
+rocking curves with full width at half maxima of $\Delta\omega \approx
+0.45^{\circ}$ are achieved. Faceting is observed along the $\alpha-Ga_2O_3$
+film surface and is explored through scanning transmission electron microscopy.",2301.13053v1
+2023-01-31,Orientation-dependent electron-phonon coupling in interfacial superconductors LaAlO3/KTaO3,"The emergent superconductivity at the LaAlO3/KTaO3 interfaces exhibits a
+mysterious dependence on the KTaO3 crystallographic orientations. Here we show,
+by soft X-ray angle-resolved photoemission spectroscopy, that the interfacial
+superconductivity is contributed by mobile electrons with unexpected
+quasi-three-dimensional character, beyond the ""two-dimensional electron gas""
+scenario in describing oxide interfaces. At differently-oriented interfaces,
+the quasi-three-dimensional electron gas ubiquitously exists and spatially
+overlaps with the small q Fuchs-Kliewer surface phonons. Intriguingly,
+electrons and the Fuchs-Kliewer phonons couple with different strengths
+depending on the interfacial orientations, and the stronger coupling correlates
+with the higher superconducting transition temperature. Our results provide a
+natural explanation for the orientation-dependent superconductivity, and the
+first evidence that interfacial orientations can affect electron-phonon
+coupling strength over several nanometers, which may have profound implications
+for the applications of oxide interfaces in general.",2301.13488v1
+2023-01-31,Enhancement in physical properties of Pb-Based Perovskite Oxides ($PbGeO_{3}$): Ab initio Calculation,"In the present paper, the electronic, structural, thermodynamic, and elastic
+properties of cubic $PbGeO_{3}$ perovskite oxide are presented and computed
+using the WIEN2K code. The structural properties have been evaluated and they
+are in good agreement with the theoretical and experimental data. A phonon
+dispersion is made and it reveals that the cubic $PbGeO_{3}$ perovskite is
+dynamically stable. In addition, the electronic properties of $PbGeO_{3}$ shows
+an opening gap energy, meaning a semiconductor behavior with an indirect band
+gap equal to $1.67 eV$. Moreover, the obtained elastic constants of cubic
+$PbGeO_{3}$ satisfy Born's mechanical stability criteria, and this indicates
+that our compound behaves as a stable ductile material. The
+temperature-pressure effects on thermodynamic parameters are investigated using
+the Gibbs$2$ package. Finally, based on the obtained results about the cubic
+$PbGeO_{3}$ perovskite properties, we assume that this compound will have
+potential applications.",2301.13493v1
+2023-02-04,A method to measure the quenching factor for recoil energy of oxygen in bismuth germanium oxide scintillators,"Bismuth germanium oxide ($\rm Bi_{4} Ge_{3} O_{12}$, BGO) scintillation
+crystals are widely used as detectors in the fields of particle physics and
+astrophysics due to their high density, and thus higher efficiency for
+gamma-ray detection. Owing to their good chemical stability, they can be used
+in any environment. For rare-event searches, such as dark matter and coherent
+elastic neutrino-nucleus scattering, BGO crystals are essential to comprehend
+the response of nuclear recoil. In this study, we have analyzed the events of
+neutron elastic scattering with oxygen in BGO crystals. Then, we have measured
+the quenching factor for oxygen recoil energy in the BGO crystal as a function
+of recoil energy by using a monoenergetic neutron source.",2302.02111v3
+2023-02-09,Understanding the role of entropy in high entropy oxides,"The field of high entropy oxides (HEOs) flips traditional materials science
+paradigms on their head by seeking to understand what properties arise in the
+presence of profound configurational disorder. This disorder, which originates
+from multiple elements sharing a single lattice site, can take on a
+kaleidoscopic character due to the vast numbers of possible elemental
+combinations. High configurational disorder appears to imbue some HEOs with
+functional properties that far surpass their non-disordered analogs. While
+experimental discoveries abound, efforts to characterize the true magnitude of
+the configurational entropy and understand its role in stabilizing new phases
+and generating superior functional properties have lagged behind. Understanding
+the role of configurational disorder in existing HEOs is the crucial link to
+unlocking the rational design of new HEOs with targeted properties. In this
+Perspective, we attempt to establish a framework for articulating and beginning
+to address these questions in pursuit of a deeper understanding of the true
+role of entropy in HEOs.",2302.04394v1
+2023-02-13,Electric control of two-dimensional Van Hove singularity in oxide ultra-thin films,"Divergent density of states (DOS) can induce extraordinary phenomena such as
+significant enhancement of superconductivity and unexpected phase transitions.
+Moreover, van Hove singularities (VHSs) are known to lead to divergent DOS in
+two-dimensional (2D) systems. Despite the recent interest in VHSs, only a few
+controllable cases have been reported to date. In this work, we investigate the
+electronic band structures of a 2D VHS with angle-resolved photoemission
+spectroscopy and control transport properties by utilizing an atomically
+ultrathin SrRuO$_3$ film. By applying electric fields with alkali metal
+deposition and ionic-liquid gating methods, we precisely control the 2D VHS,
+and the sign of the charge carrier. Use of a tunable 2D VHS in an atomically
+flat oxide film could serve as a new strategy to realize infinite DOS near the
+Fermi level, thereby allowing efficient tuning of electric properties.",2302.06222v2
+2023-02-13,Atomic scale understanding of the role of hydrogen and oxygen segregation in the embrittlement of grain boundaries in a twinning induced plasticity steel,"Twinning induced plasticity (TWIP) steels are high strength metallic
+materials with potential for structural components in e.g. automotive
+applications. However, they are prone to hydrogen embrittlement (HE) and
+galvanic corrosion. We investigated the susceptibility of a model Fe 27Mn 0.3C
+(wt%) TWIP steel towards HE and oxidation at the sub-nanometer scale by atom
+probe tomography. We measured segregation of hydrogen and oxygen at grain
+boundaries, which appears to be associated to a strong manganese depletion. Our
+study suggests a correlation between HE and oxidation mechanisms in TWIP
+steels, which we argue can combine to favor the previously reported hydrogen
+enhanced decohesion (HEDE) of grain boundaries.",2302.06317v2
+2023-02-27,Novel supercell compounds of layered Bi-Rh-O with $p$-type metallic conduction materialized as a thin film form,"Layered oxides have been intensively studied due to their high degree of
+freedom in designing various electromagnetic properties and functionalities.
+While Bi-based layered supercell (LSC) compounds
+[Bi$_n$O$_{n+\delta}$]-[$M$O$_2$] ($M$ = Mn, Mn/Al, Mn/Fe, or Mn/Ni; $n=2, 3$)
+are a group of prospective candidates, all of the reported compounds are
+insulators. Here, we report on the synthesis of two novel metallic LSC
+compounds [Bi$_{n}$O$_{n+\delta}$]-[RhO$_2$] ($n=2, 3$) by pulsed laser
+deposition and subsequent annealing. With tuning the thickness of the
+sublattice from Bi$_2$O$_{2+\delta}$ to Bi$_3$O$_{3+\delta}$, a
+dimensionality-dependent electrical transport is revealed from a conventional
+metallic transport in $n=2$ to a localized transport in $n=3$. Our successful
+growth will be an important step for further exploring novel layered oxide
+compounds.",2302.13538v1
+2023-02-28,Near-field localization of the boson peak on tantalum films for superconducting quantum devices,"Superconducting circuits are among the most advanced quantum computing
+technologies, however their performance is currently limited by losses found in
+surface oxides and disordered materials. Here, we identify and spatially
+localize a near-field signature of loss centers on tantalum films using
+terahertz scattering-type scanning near-field optical microscopy (s-SNOM).
+Making use of terahertz nanospectroscopy, we observe a localized excess
+vibrational mode around 0.5 THz and identify this resonance as the boson peak,
+a signature of amorphous materials. Grazing-incidence wide-angle x-ray
+scattering (GIWAXS) shows that oxides on freshly solvent-cleaned samples are
+amorphous, whereas crystalline phases emerge after aging in air. By localizing
+defect centers at the nanoscale, our characterization techniques and results
+will inform the optimization of fabrication procedures for new low-loss
+superconducting circuits.",2302.14316v1
+2023-03-02,Stoichiometric growth of SrTiO3 films via Bayesian optimization with adaptive prior mean,"Perovskite insulator SrTiO3 is expected to be applied to the next generation
+of electronic and photonic devices as high-k capacitors and photocatalysts.
+However, reproducible growth of highly insulating stoichiometric SrTiO3 films
+remains challenging due to the difficulty of the precise stoichiometry control
+in perovskite oxide films. Here, to grow stoichiometric SrTiO3 thin films by
+fine-tuning multiple growth conditions, we developed a new Bayesian
+optimization (BO)-based machine learning method that encourages the exploration
+of the search space by varying the prior mean to get out of suboptimal growth
+condition parameters. Using simulated data, we demonstrate the efficacy of the
+new BO method, which reproducibly reaches the global best conditions. With the
+BO method implemented in machine-learning-assisted molecular beam epitaxy
+(ML-MBE), highly insulating stoichiometric SrTiO3 film with no absorption in
+the band gap was developed in only 44 MBE growth runs. The proposed algorithm
+provides an efficient experimental design platform that is not as dependent on
+the experience of individual researchers and will accelerate not only oxide
+electronics but also various material syntheses.",2303.00929v1
+2023-03-07,"Graphene oxide: new opportunities for optoelectronic, electronic and photonic chips","As a derivative of graphene, graphene oxide (GO) was initially developed by
+chemists to emulate some of the key properties of graphene, but it was soon
+recognized as a unique material in its own right, addressing an application
+space that is not accessible to chemical vapor deposition based materials. Over
+the past decade, GO has emerged as a new frontier material with tremendous
+advances in its material fabrication and quality control over its properties.
+These in turn have led to rapid progress in GO based photonics, electronics,
+and optoelectronics concepts and devices, evoking new science and paving the
+way for many technological breakthroughs with exceptional performance. Here, we
+review the unique fundamental characteristics of GO, its thin film fabrication
+methods, patterning techniques, and mechanisms for tuning its material
+properties. This latter capability in particular has enabled novel advanced
+functional photonic, electronic, and optoelectronic devices. Understanding
+these insights is essential for designing and tailoring GO properties for
+state-of-the-art applications including solar energy harvesting, energy
+storage, medical diagnosis, image displays, and optical communications. We
+conclude by discussing the open challenges and exciting opportunities of this
+field, together with future prospects for major technological advancements and
+breakthroughs.",2303.03604v1
+2023-03-13,Linking stability with molecular geometries of perovskites and lanthanide richness using machine learning methods,"Oxide perovskite materials of type ABO3 have a wide range of technological
+applications, such as catalysts in solid oxide fuel cells and as
+light-absorbing materials in solar photovoltaics. These materials often exhibit
+differential structural and electrostatic properties through lanthanide or
+non-lanthanide derived A- and B- sites. Although, experimental and/or
+computational verification of these differences are often difficult. In this
+paper, we thus take a data-driven approach. Specifically, we run three analysis
+using the dataset Li, Jacobs, and Morgan [2018a] applying advanced machine
+learning tools to perform nonparametric regressions and also to produce data
+visualizations using latent factor analysis (LFA) and principal component
+analysis (PCA). We also implement a nonparametric feature screening step while
+performing our high dimensional regression analysis, ensuring robustness in our
+results",2303.07441v3
+2023-03-30,Impact of iso-structural template layer on stabilizing pyrochlore Bi$_2$Rh$_2$O$_7$,"We present an epitaxial stabilization of pyrochlore Bi$_2$Rh$_2$O$_7$ on
+Y-stabilized ZrO$_2$ (YSZ) (111) substrate by inserting a pyrochlore
+Eu$_2$Ti$_2$O$_7$ template layer, otherwise Bi-based layered structures being
+formed directly on YSZ (111) substrate. This result reveals that
+""iso-structural crystal phase"" plays an important role in the interfacial phase
+control. The Bi$_2$Rh$_2$O$_7$ film exhibits $p$-type electrical conduction
+with the lowest longitudinal resistivity ($\rho_\mathrm{xx}$) among the
+reported Rh pyrochlore oxides. Such parameters as $\rho_\mathrm{xx}$, carrier
+density, and mobility show almost no temperature dependence in the measured
+range of 2$-$300 K, indicating Bi$_2$Rh$_2$O$_7$ as one of the rare examples of
+conducting pyrochlore oxides.",2303.17136v1
+2023-03-31,Direct-write projection lithography of quantum dot micropillar single photon sources,"We have developed a process to mass-produce quantum dot micropillar cavities
+using direct-write lithography. This technique allows us to achieve high volume
+patterning of high aspect ratio pillars with vertical, smooth sidewalls
+maintaining a high quality factor for diameters below 2.0 $\mu$m. Encapsulating
+the cavities in a thin layer of oxide (Ta$_2$O$_5$) prevents oxidation in the
+atmosphere, preserving the optical properties of the cavity over months of
+ambient exposure. We confirm that single dots in the cavities can be
+deterministically excited to create high purity indistinguishable single
+photons with interference visibility $(96.2\pm0.7)\%$.",2304.00141v1
+2023-04-03,Navigating phase diagram complexity to guide robotic inorganic materials synthesis,"Efficient synthesis recipes are needed both to streamline the manufacturing
+of complex materials and to accelerate the realization of theoretically
+predicted materials. Oftentimes the solid-state synthesis of multicomponent
+oxides is impeded by undesired byproduct phases, which can kinetically trap
+reactions in an incomplete non-equilibrium state. We present a thermodynamic
+strategy to navigate high-dimensional phase diagrams in search of precursors
+that circumvent low-energy competing byproducts, while maximizing the reaction
+energy to drive fast phase transformation kinetics. Using a robotic inorganic
+materials synthesis laboratory, we perform a large-scale experimental
+validation of our precursor selection principles. For a set of 35 target
+quaternary oxides with chemistries representative of intercalation battery
+cathodes and solid-state electrolytes, we perform 224 reactions spanning 27
+elements with 28 unique precursors. Our predicted precursors frequently yield
+target materials with higher phase purity than when starting from traditional
+precursors. Robotic laboratories offer an exciting new platform for data-driven
+experimental science, from which we can develop new insights into materials
+synthesis for both robot and human chemists.",2304.00743v2
+2023-04-21,"Comparison of Matlantis and VASP bulk formation and surface energies in metal hydrides, carbides, nitrides, oxides, and sulfides","Generic neural network potentials without forcing users to train potentials
+could result in significantly acceleration of total energy calculations.
+Takamoto et al. [Nat. Commun. (2022), 13, 2991] developed such a deep neural
+network potential (NNP) and made it available in their Matlantis package. We
+compared the Matlantis bulk formation, surface, and surface O vacancy formation
+energies of metal hydrides, carbides, nitrides, oxides, and sulfides with our
+previously calculated VASP values obtained from first-principles with the
+PBEsol(+U) functional. Matlantis bulk formation energies were consistently ~0.1
+eV/atom larger and the surface energies were typically ~10 meV/{\AA}^2 smaller
+than the VASP counterpart. Surface O vacancy formation energies were generally
+underestimated within ~0.8 eV. These results suggest that Matlantis energies
+could serve as a relatively good descriptor of the VASP bulk formation and
+surface energies.",2304.10820v1
+2023-04-06,A Framework for Combustion Chemistry Acceleration with DeepONets,"A combustion chemistry acceleration scheme is developed based on deep
+operator networks (DeepONets). The scheme is based on the identification of
+combustion reaction dynamics through a modified DeepOnet architecture such that
+the solutions of thermochemical scalars are projected to new solutions in small
+and flexible time increments. The approach is designed to efficiently implement
+chemistry acceleration without the need for computationally expensive
+integration of stiff chemistry. An additional framework of latent-space
+dynamics identification with modified DeepOnet is also proposed which enhances
+the computational efficiency and widens the applicability of the proposed
+scheme. The scheme is demonstrated on simple chemical kinetics of hydrogen
+oxidation to more complex chemical kinetics of n-dodecane high- and
+low-temperature oxidations. The proposed framework accurately learns the
+chemical kinetics and efficiently reproduces species and temperature temporal
+profiles corresponding to each application. In addition, a very large speed-up
+with a great extrapolation capability is also observed with the proposed
+scheme.",2304.12188v1
+2023-04-27,On the structure-to-property relationship of polyanilines. A modern quantum chemistry perspective,"We employ state-of-the-art quantum chemistry methods to study the
+structure-to-property relationship in polyanilines (PANIs) of different lengths
+and oxidation states. Specifically, we focus on leucoemeraldine, emeraldine,
+and pernigraniline in their tetramer and octamer forms. We scrutinize their
+structural properties, HOMO and LUMO energies, HOMO-LUMO gaps, and vibrational
+and electronic spectroscopy using various Density Functional Approximations
+(DFAs). Furthermore, the accuracy of DFAs is assessed by comparing them to
+experimental and wavefunction-based reference data. For that purpose, we
+performed large-scale orbital-optimized pair-Coupled Cluster Doubles (oo-pCCD)
+calculations for ground and electronically excited states and conventional
+Configuration Interaction Singles (CIS) calculations for electronically excited
+states in all investigated systems. Furthermore, we augment our study with a
+quantum informational analysis of orbital correlations in various forms of
+PANIs. Our study highlights the growing multi-reference nature of PANIs with
+the length of the polymer. While structural and vibrational features of the
+investigated PANIs, regardless of their oxidation states, are adequately
+modeled in the tetramer forms, the length of the PANI chain profoundly affects
+electronic spectra. Specifically, polymer elongation changes the character of
+the leading transitions in the lowest-lying excited states in all investigated
+PANIs.",2304.14547v1
+2023-04-28,Ab-initio study of short-range ordering in vanadium-based disordered rocksalt structures,"Disordered rocksalt Li-excess (DRX) compounds are attractive new cathode
+materials for Li-ion batteries as they contain resource-abundant metals and do
+not require the use of cobalt or nickel. Understanding the delithiation process
+and cation short-range ordering (SRO) in DRX compounds is essential to
+improving these promising cathode materials. Herein, we use first-principles
+calculations along with the cluster-expansion approach to model the disorder in
+DRX Li2-xVO3, 0 < x < 1. We discuss the SRO of Li in tetrahedral and octahedral
+sites, and the order in which Li delithiates and V oxidizes with respect to
+local environments. We reveal that the number of nearest-neighbor V dictates
+the order of delithiation from octahedral sites and that V are oxidized in a
+manner that minimizes the electrostatic interactions among V. Our results
+provide valuable insight for tailoring the performance of V-based DRX cathode
+materials in general by controlling the SRO features that reduce energy
+density.",2304.14645v1
+2023-04-27,Real-time spectroscopic monitoring of continuous synthesis of zinc oxide nanostructures in femtosecond laser fabricated 3D microfluidic microchannels with integrated on-chip fiber probe array,"Materials synthesis in a microfluidic environment enables the flexible and
+controllable production of various types of nanostructures which are of great
+potential in the fields of chemistry, environmental science, bioengineering,
+and medicine. Here, we demonstrate on-chip simultaneous continuous-flow
+synthesis and in-situ spectrum diagnosis of zinc oxide (ZnO) nanomaterials
+using a femtosecond-fabricated three-dimensional microchannel reactor
+integrated with an array of optical fiber probes. The microchannel reactor
+including 3D concentration gradient generators followed by 3D micromixing units
+provides high-efficiency manipulation of reactants with different
+concentrations as well as parallel reaction dynamics in an autonomous manner.
+The integrated optical fiber probe array allows precise and parallel spectropic
+detection in different microchannels with high spatial and temporal resolutions
+for screening the synthetic conditions. The synthesized ZnO nanostructures can
+be tailored in size, shape, and morphology by tuning the flow rates and
+reactant concentrations based on the spectroscopic signals detected with the
+fiber probe array.",2305.00920v1
+2023-05-04,Photostrictive actuators based on freestanding ferroelectric membranes,"Complex oxides offer a wide range of functional properties, and recent
+advances in fabrication of freestanding membranes of these oxides are adding
+new mechanical degrees of freedom to this already rich functional ecosystem.
+Here, we demonstrate photoactuation in freestanding thin film resonators of
+ferroelectric Barium Titanate (BaTiO3) and paraelectric Strontium Titanate
+(SrTiO3). The free-standing films, transferred onto perforated supports, act as
+nano-drums, oscillating at their natural resonance frequency when illuminated
+by a frequency-modulated laser. The light-induced deflections in the
+ferroelectric BaTiO3 membranes are two orders of magnitude larger than in the
+paraelectric SrTiO3 ones. Time-resolved X-ray micro-diffraction under
+illumination and temperature-dependent and holographic interferometry provide
+combined evidence for the photostrictive strain in BaTiO3 originating from
+partial screening of ferroelectric polarization by photo-excited carriers,
+which decreases the tetragonality of the unit cell. These findings showcase the
+potential of photostrictive freestanding ferroelectric films as wireless
+actuators operated by light.",2305.03193v2
+2023-05-05,K. Alex Müller: Science between ferroelectricity and superconductivity,"K. Alex M\""uller started his scientific career in 1958 when he was about
+thirty-one years old. After his wife passed away and being in his nineties, his
+interest in physics gradually faded. In those years shortly before he passed
+away, on January 9, 2023, he was no longer interested in superconductivity or
+ferroelectricity, he had become essentially devoted to philosophy and
+psychology. It is of note that altogether his research in physics comprised
+sixty years of activity. Almost in the middle of this period, he was awarded
+the Nobel Prize in Physics for the discovery of high-temperature
+superconductivity in ceramic copper oxides in 1987. This discovery made him
+truly famous. While most researchers are familiar with his Nobel Prize work,
+many are not aware of the fact that K. Alex M\""uller was already an acclaimed
+scientist before that and highly respected in the field of perovskite oxides,
+ferroelectricity, structural phase transitions, Jahn-Teller physics, electron
+paramagnetic resonance (EPR) and, especially so in the properties of SrTiO3.",2305.03705v1
+2023-05-09,Thermodynamic route of Nb3Sn nucleation: Role of oxygen,"Intermetallic Nb3Sn alloys have long been believed to form through Sn
+diffusion into Nb. However, our observations of significant oxygen content in
+Nb3Sn prompted an investigation of alternative formation mechanisms. Through
+experiments involving different oxide interfaces (clean HF-treated, native
+oxidized, and anodized), we demonstrate a thermodynamic route that
+fundamentally challenges the conventional Sn diffusion mechanism for Nb3Sn
+nucleation. Our results highlight the critical involvement of a SnOx
+intermediate phase. This new nucleation mechanism identifies the principles for
+growth optimization and new synthesis of high-quality Nb3Sn superconductors.",2305.05114v2
+2023-05-13,Characteristic time of transient response of solid oxide cells (SOCs) to changes in voltage/current: from theory to applications,"The intermittency of solar and wind power can be addressed by integrating
+them with Solid Oxide Cells (SOCs). This study delves into the transient
+characteristics of SOCs and their dependence on dynamic heat and mass transfer
+processes. Non-dimensional analysis was used to identify influential
+parameters, followed by a 3-D numerical simulation-based parametric analysis to
+examine the dynamic gaseous and thermal responses of SOCs with varying
+dimensions, material properties, and operating conditions. For the first time,
+we proposed characteristic times to describe the relationship between SOC
+transients and multiple parameters. These characteristic times represent the
+overall heat and mass transfer rats in SOCs. Their effectiveness was validated
+against literature and demonstrated potential in characterizing the transient
+characteristics of other electrochemical cells. Besides, two examples are
+provided to illustrate how the characteristic times facilitate SOC design and
+control at minimal computational cost.",2305.07926v1
+2023-05-18,Unfaulting mechanisms of Frank loops in fluorite oxides,"Unfaulting of Frank loops in irradiated fluoride oxides are of significance
+to microstructural evolution. However, the mechanisms have not been directly
+observed. To this end, we utilize molecular dynamics to reveal the atomistic
+details related to the unfaulting process of interstitial Frank loop in
+ThO$_2$, which involve nucleation of single or multiple Shockley partial pairs
+at the loop circumference. The unfaulting is achieved via a synchronous shear
+of the partial pairs to remove the extrinsic stacking fault in the cation
+sublattice and the intrinsic stacking fault in the anion sublattice. The strong
+oxygen motion at the dislocation core may reduce the activation barriers of
+dislocation nucleation and migration. These findings provide a fundamental
+understanding of the transformation of faulted loops in irradiated ThO$_2$, and
+could be transferable to other fluorite systems.",2305.11127v1
+2023-05-08,Role of Nano-fertilizer in Plants Nutrient Use Efficiency (NUE)- A mini-review,"Over the past half-century, the combination of technology and innovation has
+been developed to manage the negative impact of synthetic fertilizer on land
+ecosystems to identify the limitations of sustainability and optimize
+agricultural systems. The application of nano-fertilizers has achieved
+considerable interest due to their significant role as environmentally
+sustainable resources and soil health. Moreover, the increasing global
+population increased food insecurity, especially under climate change.
+Nanotechnology has emerged as a promising alternative to help improving crop
+growth and productivity. However, un-balanced presence and long-term use of
+nano-particles alter photosynthesis, and induce cellular redox imbalances
+resulting in lipid peroxidation, protein oxidation and DNA oxidative damage in
+plants, so more studies are still needed on their safe application with minimum
+side effects. In this paper, we reviewed nano-fertilizer mechanisms in plant,
+as well as their effects on microbiome and interaction with soil colloids. This
+study reviews the recent studies and findings about role of Nanotechnology in
+plant nutrition use efficiency to summarize a better understanding of this
+important issue. A comprehensive picture of ecological issues such as soil and
+water contamination in response to nano-fertilizer application will also be
+assessed.",2305.14357v1
+2023-05-27,"Bond formation at polycarbonate | X interfaces (X = Al$_2$O$_3$, TiO$_2$, TiAlO$_2$) studied by theory and experiments","Interfacial bond formation during sputter deposition of metal oxide thin
+films onto polycarbonate (PC) is investigated by ab initio molecular dynamics
+simulations and X-ray photoelectron spectroscopy (XPS) analysis of PC | X
+interfaces (X = Al$_2$O$_3$, TiO$_2$, TiAlO$_2$). Generally, the predicted bond
+formation is consistent with the experimental data. For all three interfaces,
+the majority of bonds identified by XPS are (C-O)-metal bonds, whereas C-metal
+bonds are the minority. Compared to the PC | Al$_2$O$_3$ interface, the PC |
+TiO$_2$ and PC | TiAlO$_2$ interfaces exhibit a reduction in the measured
+interfacial bond density by ~ 75 and ~ 65%, respectively. Multiplying the
+predicted bond strength with the corresponding experimentally determined
+interfacial bond density shows that Al$_2$O$_3$ exhibits the strongest
+interface with PC, while TiO$_2$ and TiAlO$_2$ exhibit ~ 70 and ~ 60% weaker
+interfaces, respectively. This can be understood by considering the complex
+interplay between the metal oxide composition, the bond strength as well as the
+population of bonds that are formed across the interface.",2305.17430v1
+2023-05-30,VO2 Phase Change Electrodes in Li-ion Batteries,"Use of electrode materials that show phase change behavior and hence drastic
+changes in electrochemical activity during operation, have not been explored
+for Li-ion batteries. Here we demonstrate the vanadium oxide (VO2) cathode that
+undergoes metal-insulator transition due to first-order structural phase
+transition at accessible temperature of 68{\deg}C for battery operation. Using
+a suitable electrolyte operable across the phase transition range and
+compatible with vanadium oxide cathodes, we studied the effect of electrode
+structure change on lithium insertion followed by the electrochemical
+characteristics above and below the phase transition temperature. The
+high-temperature VO2 phase shows significantly improved capacitance, enhanced
+current rate capabilities, improved electrical conductivity and lithium-ion
+diffusivity compared to the insulating low temperature phase. This opens up new
+avenues for electrode designs, allowing manipulation of electrochemical
+reactions around phase transition temperatures, and in particular enhancing
+electrochemical properties at elevated temperatures contrary to existing
+classes of battery chemistries that lead to performance deterioration at
+elevated temperatures.",2305.19002v1
+2023-06-05,Extraordinary Tunneling Magnetoresistance in Antiferromagnetic Tunnel Junctions with Antiperovskite Electrodes,"Recent theoretical predictions and experimental demonstrations of a large
+tunneling magnetoresistance (TMR) effect in antiferromagnetic (AFM) tunnel
+junctions (AFMTJs) offer a new paradigm for information technologies where the
+AFM N\`eel vector serves as a state variable. A large TMR is beneficial for the
+applications. Here, we predict the emergence of an extraordinary TMR (ETMR)
+effect in AFMTJs utilizing noncollinear AFM antiperovskite XNMn$_{3}$ (X = Ga,
+Sn,...) electrodes and a perovskite oxide ATiO$_{3}$ (A = Sr, Ba,...) barrier
+layer. The ETMR effect stems from the perfectly spin-polarized electronic
+states in the AFM antiperovskites that can efficiently tunnel through the
+low-decay-rate evanescent states of the perovskite oxide while preserving their
+spin state. Using an GaNMn$_{3}$/SrTiO$_{3}$/GaNMn$_{3}$ (001) AFMTJ as a
+representative example, we demonstrate a giant TMR ratio exceeding $10^{4}$%
+and originating from the ETMR effect. These results are promising for the
+efficient detection and control of the N\`eel vector in AFM spintronics.",2306.03026v1
+2023-05-30,Self-regulated ligand-metal charge transfer upon lithium ion de-intercalation process from LiCoO2 to CoO2,"Understanding the role of metal and oxygen in the redox process of layered 3d
+transition metal oxides is crucial to build high density and stable next
+generation Li-ion batteries. We combine hard X-ray photoelectron spectroscopy
+and ab-initio-based cluster model simulations to study the electronic structure
+of prototypical end-members LiCoO2 and CoO2. The role of cobalt and oxygen in
+the redox process is analyzed by optimizing the values of d-d electron
+repulsion and ligand-metal p-d charge transfer to the Co 2p spectra. We clarify
+the nature of oxidized cobalt ions by highlighting the transition from positive
+to negative ligand-to-metal charge transfer upon Li+ de-intercalation.",2306.03096v2
+2023-06-15,Characteristic THz-emissions induced by optically excited collective orbital modes,"We study the generation of collective orbital modes, their evolution, and the
+characteristic non-linear optical response induced by them in a photoinduced
+orbital-ordered correlated oxide using real-time simulations based on an
+interacting multiband tight-binding (TB) model. The d-d optical transitions
+under femtoseconds light-pulse in a orbital-ordered state excite collective
+orbital modes, also known as ""orbitons"". The consistent inclusion of electronic
+interactions and the coupling between charge, spin, and lattice degrees of
+freedom in the TB-model provide a better understanding of the underlying
+mechanisms of the collective orbital modes. The dynamics of Jahn-Teller
+vibrational modes in the photoinduced state modify the intersite orbital
+interaction, which further amplifies these orbital modes. In the presence of
+weak ferroelectricity, the excitation of collective orbital modes induces a
+strong THz oscillatory photocurrent which is long-lived. This suggests an
+alternative way to experimentally detect quasiparticles describing such
+collective modes through THz-emission studies in the photoinduced state. Our
+study also elucidates that quasiparticle dynamics in improper ferroelectric
+oxides can be exploited to achieve highly interesting and non-trivial
+optoelectronic properties.",2306.09107v1
+2023-06-27,Zinc dialkyldithiophosphates adsorption and dissociation on ferrous substrates: an ab initio study,"Zinc dialkyldithiophosphates (ZDDPs) have been commonly used as anti-wear
+additives in the automotive industry for the past 80 years. The morphology,
+composition and structure of the ZDDPs phosphate-based tribofilm, which is
+essential for its lubricant functioning, have been widely studied
+experimentally. However, despite their widespread use, a general agreement on
+their primary functioning mechanism is still lacking. The morphology and
+composition of the ZDDPs phosphate-based tribofilm have been widely studied
+experimentally, but the formation process and the relevant driving forces are
+still largely debated. In particular, it is unclear whether the stress-induced
+molecular dissociation occurs in the bulk oil or on the substrate. In this
+work, we employ ab initio density-functional theory simulations to compare ZDDP
+fragmentation in vacuum and over a reactive substrate, considering the effects
+of surface oxidation on the dissociation path. Our results show that the
+molecular dissociation is highly endothermic in the absence of a supporting
+substrate, while in the presence of an iron substrate it becomes highly
+energetically favoured. Moreover, the presence of the substrate changes the
+reaction path. At the same time, surface oxidation reduces the
+molecule-substrate interaction. These findings provide valuable insights into
+the early stages of the formation of phosphate-based tribofilms.",2306.15654v1
+2023-07-01,"Unusual nanoscale coexistence of polar-nonpolar domains underlying oxygen storage properties in Ho(Mn, Ti)O$_{3+δ}$","Hexagonal manganese oxides RMnO$_3$ show intriguing topological
+ferroelectric-domain walls with variable conductivity, leading to domain wall
+engineering. Despite the numerous experimental studies on the polar nanoscale
+structures, controlling ferroelectric domains has not been sufficiently
+investigated. Here, we reveal the unprecedented coexistence of polar-nonpolar
+nanoscale domains that can be formed by substituting Ti ions in HoMnO$_3$.
+Unusual polar nanoscale domains are embedded in nonpolar domains with different
+crystallographic symmetry. This polar-nonpolar coexisting structure is
+naturally assembled by adjusting the lattice length during a solid-state
+reaction process. Furthermore, the comprehensive study reveals that the
+reversible microstructural change with a nonpolar-polar transition is strongly
+correlated with the oxygen storage properties in Ho(Mn, Ti)O$_{3+\delta}$. The
+present results provide important insight into the nanoscale polar-nonpolar
+domain coexistence in functional rare-earth manganese oxides, RMnO$_3$.",2307.00248v1
+2023-07-03,Toward an accurate equation of state and B1-B2 phase boundary for magnesium oxide to TPa pressures and eV temperatures,"By applying auxiliary-field quantum Monte Carlo, we calculate the equation of
+state (EOS) and B1-B2 phase transition of magnesium oxide (MgO) up to 1 TPa.
+The results agree with available experimental data at low pressures and are
+used to benchmark the performance of various exchange-correlation functionals
+in density functional theory calculations. We determine PBEsol is an optimal
+choice for the exchange-correlation functional and perform extensive phonon and
+quantum molecular-dynamics calculations to obtain the thermal EOS. Our results
+provide a preliminary reference for the EOS and B1-B2 phase boundary of MgO
+from zero up to 10,500 K.",2307.01359v1
+2023-07-07,Enhancing the ultrafast third order nonlinear optical response by charge transfer in VSe2-reduced graphene oxide hybrid,"Nonlinear optical phenomena play a critical role in understanding microscopic
+light-matter interactions and have far-reaching applications across various
+fields, such as biosensing, quantum information, optical switching, and
+all-optical data processing. Most of these applications require materials with
+high third-order absorptive and refractive optical nonlinearities. However,
+most materials show weak nonlinear optical responses due to their perturbative
+nature and often need to be improved for practical applications. Here, we
+demonstrate that the charge donor-acceptor hybrid of VSe2-reduced graphene
+oxide (rGO) hybrid exhibits enhanced ultrafast third-order absorptive and
+refractive nonlinearities compared to the pristine systems, at least by one
+order of magnitude. Through density functional theory and Bader charge
+analysis, we elucidate the strong electronic coupling in the VSe2-rGO hybrid,
+involving the transfer of electrons from VSe2 to rGO. Steady-state and
+time-resolved photoluminescence (PL) measurements confirm the electronic
+coupling and charge transfer. Furthermore, we fabricate an ultrafast optical
+limiter device with better performance parameters, such as an onset threshold
+of 2.5 mJ cm-2 and differential transmittance of 0.42.",2307.03485v1
+2023-07-11,Tunable ferroelectricity in oxygen-deficient perovskites,"Using first-principles calculations, we predict that tunable ferroelectricity
+can be realized in oxide perovskites with the Grenier structure and ordered
+oxygen vacancies. Specifically, we show that
+$R_{1/3}A_{2/3}\mathrm{FeO}_{2.67}$ solids (where $R$ is a rare-earth ion and
+$A$ an alkaline-earth cation) exhibit stable polar phases, with a spontaneous
+polarization tunable by an appropriate choice of $R$ and $A$. We find that
+larger cations combined with small $R$ elements lead to a maximum in the
+polarization and to a minimum in the energy barriers required to switch the
+sign of the polarization. Ferroelectricity arises from cooperative distortions
+of octahedral and tetrahedral units, where a combination of rotational and
+sliding modes controls the emergence of polarization within three-dimensional
+connected layers. Our results indicate that polar Grenier phases of oxide
+perovskites are promising materials for microelectronic applications and, in
+general, for the study of phenomena emerging from breaking inversion symmetry
+in solids.",2307.04972v1
+2023-07-17,Titanium and titanium oxides at the K- and L-edges: validating theoretical calculations of X-ray absorption and X-ray emission spectra with measurements,"Using well-calibrated experimental data we validate theoretical X-ray
+absorption spectroscopy (XAS) as well as X-ray emission spectroscopy (XES)
+calculations for titanium (Ti), titanium oxide (TiO), and titanium dioxide
+(TiO$_2$) at the Ti K- and L-edges as well as O K-edge. XAS and XES in
+combination with a multi-edge approach offer a detailed insight into the
+electronic structure of materials since both the occupied and unoccupied
+states, are probed. The experimental results are compared with ab initio
+calculations from the OCEAN package which uses the Bethe-Salpeter equation
+(BSE) approach. Using the same set of input parameters for each compound for
+calculations at different edges, the transferability of the OCEAN calculations
+across different spectroscopy methods and energy ranges is validated. Thus, the
+broad applicability for analysing and interpreting the electronic structure of
+materials with the OCEAN package is shown.",2307.08255v1
+2023-07-18,Large scale synthesis of 2D graphene oxide by mechanical milling of 3D carbon nanoparticles in air,"Graphene oxide (GO) is one of the important functional materials. Large-scale
+synthesis of it is very challenging. Following a simple cost-effective route,
+large-scale GO was produced by mechanical (ball) milling, in air, of carbon
+nanoparticles (CNPs) present in carbon soot in the present study. The thickness
+of the GO layer was seen to decrease with an increase in milling time. Ball
+milling provided the required energy to acquire the in-plane graphitic order in
+the CNPs reducing the disorders in it. As the surface area of the layered
+structure became more and more with the increase in milling time, more and more
+oxygen of air got attached to the carbon in graphene leading to the formation
+of GO. An increase in the time of the ball mill up to 5 hours leads to a
+significant increase in the content of GO. Thus ball milling can be useful to
+produce large-scale two-dimensional GO for a short time.",2307.09011v1
+2023-07-19,Transparent conductive oxides as a material platform for photonic neural networks,"Photonics integrated circuits have a huge potential to serve as a framework
+for a new class of information processing machines and can enable ultrafast
+artificial neural networks. They can overcome the existing speed and power
+limits of the electronic processing elements and provide additional benefits of
+photonics such as high-bandwidth, sub-nanosecond latencies and low-energy
+interconnect credentials leading to a new paradigm called neuromorphic
+photonics. The main obstacle to realize such a task is a lack of proper
+material platform that imposes serious requirements on the architecture of the
+network. Here we suggest and justify that transparent conductive oxides can be
+an excellent candidate for such a task as they provide a nonlinearity and
+bistability under both optical and electrical inputs.",2307.10419v1
+2023-07-20,Morphology and dynamics of dense nanometric precursor lms of polymer melts,"Nanometer-thick supported lms of polymer melts spontaneously form and spread
+around sessile droplets that are deposited on oxidized silicon wafers. At
+steady state, the lms become dense and adopt a uniform thickness which is equal
+to twice the gyration radius of the free polymer. Remarkably, this law applies
+to a wide variety of melts and does not depend on the polymer chemistry nor on
+the surface state (oxide layer thickness, temperature, presence of water
+adsorbed, etc.). We show that existing theoretical descriptions cannot
+reproduce this experimental result. Conversely, the evolution toward this
+equilibrium state witnesses the specicity of the interactions at stake in these
+conned polymer lms. The chains spreading dynamics can be modeled by taking into
+account both the polymer/surface friction and the polymer/polymer friction.",2307.10681v1
+2023-07-20,Reconfigurable cascaded thermal neuristors for neuromorphic computing,"While the complementary metal-oxide semiconductor (CMOS) technology is the
+mainstream for the hardware implementation of neural networks, we explore an
+alternative route based on a new class of spiking oscillators we call thermal
+neuristors, which operate and interact solely via thermal processes. Utilizing
+the insulator-to-metal transition in vanadium dioxide, we demonstrate a wide
+variety of reconfigurable electrical dynamics mirroring biological neurons.
+Notably, inhibitory functionality is achieved just in a single oxide device,
+and cascaded information flow is realized exclusively through thermal
+interactions. To elucidate the underlying mechanisms of the neuristors, a
+detailed theoretical model is developed, which accurately reflects the
+experimental results. This study establishes the foundation for scalable and
+energy-efficient thermal neural networks, fostering progress in brain-inspired
+computing.",2307.11256v2
+2023-07-23,Unconventional spin polarization at Argon ion milled SrTiO3 Interfaces,"Interfacial two-dimensional electron gas (2DEG) formed at the perovskite-type
+oxide, such as SrTiO3, has attracted significant attention due to its
+properties of ferromagnetism, superconductivity, and its potential application
+in oxide-based low-power consumption electronics. Recent studies have
+investigated spin-to-charge conversion at the STO interface with different
+materials, which could affect the efficiency of this 2DEG interface. In this
+report, we presented an Ar^+ ion milling method to create a 2DEG at STO
+directly by inducing oxygen vacancies. To quantify the spin-to-charge
+conversion of this interface, we measured the angular-dependent spin-torque
+ferromagnetic resonance (ST-FMR) spectra, revealing an unconventional spin
+polarization at the interface of Argon ion-milled STO and NiFe. Furthermore, a
+micromagnetic simulation for angular-dependent spin-torque ferromagnetic
+resonance (ST-FMR) has been performed, confirming the large unconventional spin
+polarization at the interface.",2307.12390v1
+2023-06-16,Piezo-resistive pressure sensor based on CVD-grown ZnO nanowires on Polyethylene Tetrathalate substrate,"Recent developments in the domain of electronic materials and devices have
+attracted the interest of researchers toward flexible and printable electronic
+components like organic transistors, printable electrodes and sensors. Zinc
+Oxide (ZnO) nanowires (NWs) possess a number of excellent properties like high
+mobility, large exciton binding energy and the direct-band gap in addition to
+large piezoelectric coefficients. Here, we report on flexible piezo-resistive
+sensor based on Indium tin oxide (ITO)-coated Polyethylene tetrathalate (PET)
+substrate. The device shows sensitivity in terms of change in resistance from
+100 {\Omega} to 2.4 K{\Omega} at an applied potential of 5V upon bending from
+flat to 95 degrees. The 1-D nanowire flexible device in its flat state shows
+saturated output current. We observed ten folds enhanced variation as compared
+to previous reports. Improved sensitivity was observed in our experiments due
+to fewer defects in CVD-grown NWs as compared to others where hydrothermally
+grown nanowires were used. The methodology of device fabrication reported here
+requires less time and enables efficient devices for the realization of
+flexible and wearable technology.",2307.13805v1
+2023-08-01,CMOS on-chip thermometry at deep cryogenic temperatures,"Accurate on-chip temperature sensing is critical for the optimal performance
+of modern CMOS integrated circuits (ICs), to understand and monitor localized
+heating around the chip during operation. The development of quantum computers
+has stimulated much interest in ICs operating a deep cryogenic temperatures
+(typically 0.01 - 4 K), in which the reduced thermal conductivity of silicon
+and silicon oxide, and the limited cooling power budgets make local on-chip
+temperature sensing even more important. Here, we report four different methods
+for on-chip temperature measurements native to complementary
+metal-oxide-semiconductor (CMOS) industrial fabrication processes. These
+include secondary and primary thermometry methods and cover conventional
+thermometry structures used at room temperature as well as methods exploiting
+phenomena which emerge at cryogenic temperatures, such as superconductivity and
+Coulomb blockade. We benchmark the sensitivity of the methods as a function of
+temperature and use them to measure local excess temperature produced by
+on-chip heating elements. Our results demonstrate thermometry methods that may
+be readily integrated in CMOS chips with operation from the milliKelivin range
+to room temperature.",2308.00392v1
+2023-08-07,Oxide layer formation prevents deteriorating ion migration in thermoelectric Cu$_2$Se during operation in air,"Cu$_2$Se is a mixed ionic-electronic conductor with outstanding
+thermoelectric performance originally envisioned for space missions.
+Applications were discontinued due to material instability, where elemental Cu
+grows at the electrode interfaces during operation in vacuum. Here, we show
+that when Cu$_2$Se is operating in air, formation of an oxide surface layer
+suppresses Cu$^+$ migration along the current direction. In operando X-ray
+scattering and electrical resistivity measurements quantify Cu$^+$ migration
+through refinement of atomic occupancies and phase composition analysis. Cu
+deposition can be prevented during operation in air, irrespective of a critical
+voltage, if the thermal gradient is applied along the current direction.
+Maximum entropy electron density analysis provides experimental evidence that
+Cu$^+$ migration pathways under thermal and electrical gradients differ
+substantially from equilibrium diffusion. The study establishes new promise for
+inexpensive sustainable Cu$_2$Se in thermoelectric applications, and it
+underscores the importance of atomistic insight into materials during
+thermoelectric operating conditions.",2308.03559v1
+2023-08-16,Investigation of Magnesium Silicate as an Effective Gate Dielectric for AlGaN/GaN Metal Oxide High Electron Mobility Transistors (MOSHEMT),"In this study, a 6 nm layer of Magnesium Silicate (Mg-Silicate) was deposited
+on AlGaN/GaN heterostructure by sputtering of multiple stacks of MgO and
+SiO$_{2}$, followed by rapid thermal annealing in a nitrogen (N$_{2}$)
+environment. The X-ray photoelectron spectroscopy (XPS) analysis confirmed the
+stoichiometric Mg-Silicate (MgSiO$_{3}$) after being annealed at a temperature
+of 850 $^\circ$C for 70 seconds. Atomic force microscopy (AFM) was employed to
+measure the root mean square (RMS) roughness (2.20 nm) of the Mg-Silicate. A
+significant reduction in reverse leakage current, by a factor of three orders
+of magnitude, was noted for the Mg-Silicate/AlGaN/GaN metal-oxide-semiconductor
+(MOS) diode in comparison to the Schottky diode. The dielectric constant of
+Mg-Silicate($\mathcal{E}_{Mg-Silicate}$) and the interface density of states
+(D$_{it}$) with AlGaN were approximated at $\sim$ 6.6 and 2.0 $\times$
+10$^{13}$ cm$^{-2}$eV$^{-1}$ respectively, utilizing capacitance-voltage (CV)
+characteristics.",2308.08515v1
+2023-08-21,Impact of geometry on chemical analysis exemplified for photoelectron spectroscopy of black silicon,"For a smooth surface, the chemical composition can be readily evaluated by a
+variety of spectroscopy techniques; a prominent example is X-ray photoelectron
+spectroscopy (XPS), where the relative proportions of the elements are mainly
+determined by the intensity ratio of the element-specific photoelectrons. This
+deduction, however, is more intricate for a nanorough surface, such as black
+silicon, since the steep slopes of the geometry mimic local variations of the
+local emission angle. Here, we explicitly quantify this effect via an integral
+geometric analysis, by using so-called Minkowski tensors. Thus, we match the
+chemical information from XPS with topographical information from atomic force
+microscopy (AFM). Our method provides reliable estimates of layer thicknesses
+for nanorough surfaces. For our black silicon samples, we found that the oxide
+layer thickness is on average comparable to that of a native oxide layer. Our
+study highlights the impact of complex geometries at the nanoscale on the
+analysis of chemical properties with implications for a broad class of
+spectroscopy techniques.",2308.10625v1
+2023-08-16,In situ Fault Diagnosis of Indium Tin Oxide Electrodes by Processing S-Parameter Patterns,"In the field of optoelectronics, indium tin oxide (ITO) electrodes play a
+crucial role in various applications, such as displays, sensors, and solar
+cells. Effective fault detection and diagnosis of the ITO electrodes are
+essential to ensure the performance and reliability of the devices. However,
+traditional visual inspection is challenging with transparent ITO electrodes,
+and existing fault detection methods have limitations in determining the root
+causes of the defects, often requiring destructive evaluations. In this study,
+an in situ fault diagnosis method is proposed using scattering parameter
+(S-parameter) signal processing, offering early detection, high diagnostic
+accuracy, noise robustness, and root cause analysis. A comprehensive
+S-parameter pattern database is obtained according to defect states. Deep
+learning (DL) approaches, including multilayer perceptron (MLP), convolutional
+neural network (CNN), and transformer, are then used to simultaneously analyze
+the cause and severity of defects. Notably, it is demonstrated that the
+diagnostic performance under additive noise levels can be significantly
+enhanced by combining different channels of the S-parameters as input to the
+learning algorithms, as confirmed through the t-distributed stochastic neighbor
+embedding (t-SNE) dimension reduction visualization.",2308.11639v1
+2023-08-31,Manganese Dissolution in alkaline medium with and without concurrent oxygen evolution in LiMn$_2$O$_4$,"Manganese dissolution during the oxygen evolution reaction (OER) has been a
+persistent challenge that impedes the practical implementation of Mn-based
+electrocatalysts including the LiMn$_x$O$_4$ system in aqueous alkaline
+electrolyte. The investigated LiMn$_2$O$_4$ particles exhibit two distinct Mn
+dissolution processes; one independent of OER and the other associated to OER.
+Combining the bulk sensitive X-ray absorption spectroscopy, surface sensitive
+X-ray photoelectron spectroscopy and electrochemical detection of Mn
+dissolution using rotating ring-disk electrode, we explore the less understood
+Mn dissolution mechanism during OER. We correlate near-surface oxidation with
+the charge attributed to dissolved Mn, which demonstrates increasing Mn
+dissolution with the formation of surface Mn4+ species under anodic potential.
+The observed stronger dissolution during the OER is attributed to the formation
+of additional Mn$^{4+}$ from Mn$^{3+}$ during OER. We show that control over
+the amount of Mn4+ in Li$_x$Mn2O$_4$ before the onset of the OER can partially
+mitigate the OER-triggered dissolution. Overall, our atomistic insights into
+the Mn dissolution processes are crucial for knowledge-guided mitigation of
+electrocatalyst degradation, which can be broadly extended to manganese-based
+oxide systems.",2309.00101v1
+2023-08-07,Modeling of electrochemical oxide film growth -- a PDM refinement,"The Point Defect Model (PDM) is known for over 40 years and has brought
+deeper insight to the understanding of passivity. During the last decades it
+has seen several changes and refinements, and it has been widely used to
+analyze growth kinetics of different alloys. Nevertheless, the model has been
+based on still unconfirmed assumptions, as constant and potential independent
+electric field strength. To overcome this limitation, we introduce a Refined
+PDM (R-PDM) in which we replace those assumptions by using additional equations
+for charge distribution including new physically valid boundary conditions
+based on considering finite dimensions for the defects by introduction of two
+defect layer at the film boundaries and by calculating the potential drop at
+the surface of the film towards the solution over the compact double layer. The
+calculations by the R-PDM show that the original PDM assumptions are only valid
+for very specific parameter combinations of oxide film growth and vacancies
+transport and cannot generally be taken for granted. We believe our findings of
+electric field and potential drop dependency on the external potential to pave
+the way for a more realistic description of passive layer formation.",2309.04480v1
+2023-09-25,Cerium oxide catalyzed disproportionation of hydrogen peroxide: a closer look at the reaction intermediate,"Cerium oxide nanoparticles (CNPs) have recently gained increasing interest as
+redox enzyme-mimetics to scavenge the intracellular excess of reactive oxygen
+species, including hydrogen peroxide (H2O2). Despite the extensive exploration
+of CNP scavenging activity, there remains a notable knowledge gap regarding the
+fundamental mechanism underlying the CNP catalyzed disproportionation of H2O2.
+In this Letter, we present evidence demonstrating that H2O2 adsorption at CNP
+surface triggers the formation of stable intermediates known as ceriumperoxo
+complexes (Ce-O2 2-). The cerium-peroxo complexes can be resolved by Raman
+scattering and UV-Visible spectroscopy. We further demonstrate that the
+catalytic reactivity of CNPs in the H2O2 disproportionation reaction increases
+with the Ce(III) fraction. The developed approach using UV-Visible spectroscopy
+for the characterization of Ce-O2 2-complexes can potentially serve as a
+foundation for determining the catalytic reactivity of CNPs in the
+disproportionation of H2O2.",2309.13981v1
+2023-09-25,Integrated bolometric photodetectors based on transparent conductive oxides from near- to mid-infrared wavelengths,"On-chip photodetectors are essential components in optical communications as
+they convert light into an electrical signal. Photobolometers are type of
+photodetector that functions through a resistance change caused by electronic
+temperature fluctuations upon light absorption. They are widely used in the
+broad wavelength range from UV to MIR and can operate on a wide material
+platform. In this work, I introduce a novel waveguide-integrated bolometer that
+operates in a wide wavelength range from NIR to MIR on the standard material
+platform with the transparent conductive oxides (TCOs) as the active material.
+This material platform enables the construction of both modulators and
+photodetectors using the same material, which is fully CMOS compatible and
+easily integrated with passive on-chip components. The photobolometers proposed
+here consist of a thin TCO layer placed inside the rib photonic waveguide to
+enhance light absorption and then heat the electrons in the TCO to temperatures
+above 1000 K. This rise in electron temperature leads to decreasing electron
+mobility and consequential electrical resistance change. In consequence, a
+responsivity exceeding 10 A/W can be attained with a mere few microwatts of
+optical input power. Calculations suggest that further improvements can be
+expected with lower doping of the TCO, thus opening new doors in on-chip
+photodetectors.",2309.14454v1
+2023-09-27,Model-based design of temporal analysis of products (TAP) reactors: A simulated case study in oxidative propane dehydrogenation,"Temporal analysis of products (TAP) reactors enable experiments that probe
+numerous kinetic processes within a single set of experimental data through
+variations in pulse intensity, delay, or temperature. Selecting additional TAP
+experiments often involves arbitrary selection of reaction conditions or the
+use of chemical intuition. To make experiment selection in TAP more robust, we
+explore the efficacy of model-based design of experiments (MBDoE) for precision
+in TAP reactor kinetic modeling. We successfully applied this approach to a
+case study of synthetic oxidative propane dehydrogenation (OPDH) that involves
+pulses of propane and oxygen. We found that experiments identified as optimal
+through the MBDoE for precision generally reduce parameter uncertainties to a
+higher degree than alternative experiments. The performance of MBDoE for model
+divergence was also explored for OPDH, with the relevant active sites (catalyst
+structure) being unknown. An experiment that maximized the divergence between
+the three proposed mechanisms was identified and led to clear mechanism
+discrimination. However, re-optimization of kinetic parameters eliminated the
+ability to discriminate. The findings yield insight into the prospects and
+limitations of MBDoE for TAP and transient kinetic experiments.",2309.15786v2
+2023-10-02,Estimation of In-Vitro Free Radical Scavenging and Cytotoxic Activities of Thiocarbohydrazones Derivatives,"Objective: To investigate free radical scavenging potential of
+thiocarbohydrazones derivatives for the discovery of antioxidant compounds of
+synthetic origin. Method: Eighteen thiocarbohydrazones derivatives were
+screened for antioxidant activities by using in vitro radical inhibition assay.
+Cytotoxicity all derivatives were evaluated using invitro cytotoxicity assay on
+mouse fibroblast cell line. Results: various compounds of the have shown
+significant radical scavenging activities as compared with the standard drug
+butylated hydroxytoluene. In addition in an in vitro cell cytotoxicity assay
+selected analogues were found to be non-cytotoxic against fibroblast 3T3 cell
+line. Conclusion: Taken together, these findings all compound this series could
+be further evaluated in in vivo model of oxidative stress to develop as a
+therapeutic agent against oxidative stress related disorders due to exhibiting
+excellent free radical scavenging properties and having their non cytotoxic
+nature against normal cells.",2310.00939v1
+2023-10-05,Visualising emergent phenomena at oxide interfaces,"Knowledge of atomic-level details of structure, chemistry, and electronic
+states is paramount for a comprehensive understanding of emergent properties at
+oxide interfaces. We utilise a novel methodology based on atomic-scale electron
+energy loss spectroscopy (EELS) to spatially map the electronic states tied to
+the formation of a two-dimensional electron gas (2DEG) at the prototypical
+non-polar/polar $TiO_2$/$LaAlO_3$ interface. Combined with differential phase
+contrast analysis we directly visualise the microscopic locations of ions and
+charge and find that 2DEG states and $Ti^{3+}$ defect states exhibit different
+spatial distributions. Supported by density functional theory (DFT) and
+inelastic scattering simulations we examine the role of oxygen vacancies in
+2DEG formation. Our work presents a general pathway to directly image emergent
+phenomena at interfaces using this unique combination of arising microscopy
+techniques with machine learning assisted data analysis procedures.",2310.03863v1
+2023-10-10,To what extent airborne particulate matters are influenced by ammonia and nitrogen oxides?,"Intensive farming is known to significantly impact air quality, particularly
+fine particulate matter (PM$_{2.5}$). Understanding in detial their relation is
+important for scientific reasons and policy making. Ammonia emissions convey
+the impact of farming, but are not directly observed. They are computed through
+emission inventories based on administrative data and provided on a regular
+spatial grid at daily resolution. In this paper, we aim to validate
+\textit{lato sensu} the approach mentioned above by considering ammonia
+concentrations instead of emissions in the Lombardy Region, Italy. While the
+former are available only in few monitoring stations around the region, they
+are direct observations. Hence, we build a model explaining PM2.5 based on
+precursors, ammonia (NH3) and nitrogen oxides (NOX), and meteorological
+variables. To do this, we use a seasonal interaction regression model allowing
+for temporal autocorrelation, correlation between stations, and
+heteroskedasticity. It is found that the sensitivity of PM2.5 to NH3 and NOX
+depends on season, area, and NOX level. It is recommended that an emission
+reduction policy should focus on the entire manure cycle and not only on spread
+practices.",2310.09302v2
+2023-10-16,An analysis on improvement of x-ray diffractometer results by controlling and calibration of parameters,"The X-ray diffractometer in the laboratory is a crucial instrument for
+analyzing materials in science. It can be used on almost any crystal material,
+and if the machine parameters are appropriately controlled, it can offer a lot
+of information about the samples characteristics. Nevertheless, the data
+obtained from these machines are complicated by an aberration function that can
+be resolved through calibration. In this study, a powder comprising of Barium
+Sulfate (BaSO4), Zinc Oxide (ZnO) and Aluminum (Al) was used as the first
+sample and a single crystal sample comprised of Gallium Nitride (GaN) and
+Aluminum Oxide (Al2O3). The required calibration parameters of the X-ray
+diffractometer namely: Straight Beam Alignment, Beam Cut Alignment and Sample
+Tilt Alignment for two samples were analyzed and carried out. Using the results
+of the X-ray spectrum, important parameters such as corresponding planes for
+peak positions, d-spacing of planes, intensities, smallest crystallite sizes
+and lattice parameters, and a comparison with the reference data were all
+carried out. As another result, the out-of-plane alignment and Full-Width at
+Half-Maximum (FWHM) value for GaN could be determined using the rocking curve.",2310.10786v1
+2023-10-18,Structures and Electronic States of Nickel Rich Oxides for Lithium Ion Batteries,"A new superstructure of layered pristine LiNiO2 (LNO) was obtained optimizing
+a large supercell of the 166 space group, the one observed experimentally by
+XRD, and relaxing both cell parameters and internal positions. The crystal
+structure shows size and charge disproportionation of the NiO6 octahedra
+instead of the Jahn-Teller distortion. The decrease of the internal energy
+obtained with the structural optimization of the supercell relative to the same
+structure in its primitive unit cell is much larger than the one obtained by
+relaxing similarly dimensioned supercells of monoclinic symmetry relative to
+their primitive unit cells, although the monoclinic phase remains more stable.
+The Ni-O bond length distribution of the new structure agree well with the
+experiments. Our results show that the choice of the simulation cell is
+important for determining the energetics of this class of oxide materials,
+proposed for cathodes in lithium ion batteries (LIBs). We used this new
+structure as a template for the study of the structural and electronic changes
+induced by the delithiation and Mn for Ni cation substitution, originating the
+solid solutions LiNiyMn(1-y)O2 (LNMO). Our results, surprisingly, agree well
+with the existing experiments and explain observed trends better than previous
+studies.",2310.11856v1
+2023-10-22,The Oxygen Reduction Pathway for Spinel Metal Oxides in Alkaline Media: An Experimentally Supported Ab Initio Study,"Precious-metal-free spinel oxide electrocatalysts are promising candidates
+for catalyzing the oxygen reduction reaction (ORR) in alkaline fuel cells. In
+this theory-driven study, we use joint density-functional theory in tandem with
+supporting electrochemical measurements to identify a novel theoretical pathway
+for the ORR on cubic Co3O4 nanoparticle electrocatalysts. This pathway aligns
+more closely with experimental results than previous models. The new pathway
+employs the cracked adsorbates *(OH)(O) and *(OH)(OH), which, through hydrogen
+bonding, induce spectator surface *H. This results in an onset potential
+closely matching experimental values, in stark contrast to the traditional ORR
+pathway, which keeps adsorbates intact and overestimates the onset potential by
+0.7 V. Finally, we introduce electrochemical strain spectroscopy (ESS), a
+groundbreaking strain analysis technique. ESS combines ab initio calculations
+with experimental measurements to validate proposed reaction pathways and
+pinpoint rate-limiting steps.",2310.14377v1
+2023-10-24,Identifying bimodality in data using a proximity-based null model with an application to classifying cell cycle phases using oxidative stress,"Detecting communities in large complex networks has found a wide range of
+applications in physical, biological, and social sciences by identifying
+mesoscopic groups based on the links between individual units. Moreover,
+community detection approaches have been generalized to various data analysis
+tasks by constructing networks whose links depend on individual units'
+measurements. However, identifying well-separated subpopulations in data sets,
+e.g., multimodality, still presents challenges as both community detection with
+existing null models and other partition methods give partitions that do not
+necessarily correspond to multimodality. Here we introduce a new spatially
+informed null model for this task that takes into account spatial structure but
+does not explicitly depend on distances between measurements. We find that
+community detection using this null model successfully identifies
+subpopulations in multimodal data and accurately does not for unimodal data. We
+apply this new null model to first distinguish interphase and mitotic cell
+cycle phases and then S and G2 cell cycle phases in a group of Dictyostelium
+discoideum cells using measurements of oxidative stress, which have been shown
+to correlate strongly with cell-cycle behaviors.",2310.16078v2
+2023-10-27,Practical application of quantum neural network to materials informatics: prediction of the melting points of metal oxides,"Quantum neural network (QNN) models have received increasing attention owing
+to their strong expressibility and resistance to overfitting. It is
+particularly useful when the size of the training data is small, making it a
+good fit for materials informatics (MI) problems. However, there are only a few
+examples of the application of QNN to multivariate regression models, and
+little is known about how these models are constructed. This study aims to
+construct a QNN model to predict the melting points of metal oxides as an
+example of a multivariate regression task for the MI problem. Different
+architectures (encoding methods and entangler arrangements) are explored to
+create an effective QNN model. Shallow-depth ansatzs could achieve sufficient
+expressibility using sufficiently entangled circuits. The ""linear"" entangler
+was adequate for providing the necessary entanglement. The expressibility of
+the QNN model could be further improved by increasing the circuit width. The
+generalization performance could also be improved, outperforming the classical
+NN model. No overfitting was observed in the QNN models with a well-designed
+encoder. These findings suggest that QNN can be a useful tool for MI.",2310.17935v1
+2023-10-27,Collisional shift and broadening of Rydberg states in nitric oxide at room temperature,"We report on the collisional shift and line broadening of Rydberg states in
+nitric oxide (NO) with increasing density of a background gas at room
+temperature. As a background gas we either use NO itself or nitrogen (N$_{2}$).
+The precision spectroscopy is performed by a sub-Doppler three-photon
+excitation scheme with a subsequent readout of the Rydberg states realized by
+the amplification of a current generated by free charges due to collisions. The
+shift shows a dependence on the rotational quantum state of the ionic core and
+no dependence on the principle quantum number of the orbiting Rydberg electron.
+The experiment was performed in the context of developing a trace-gas sensor
+for breath-gas analysis in a medical application.",2310.18256v2
+2023-11-02,Unravelling the atomic and electronic structure of nanocrystals on superconducting Nb(110): Impact of the oxygen monolayer,"The Niobium surface is almost always covered by a native oxide layer which
+greatly influences the performance of superconducting devices. Here we
+investigate the highly stable Niobium oxide overlayer of Nb(110), which is
+characterised by its distinctive nanocrystal structure as observed by scanning
+tunnelling microscopy (STM). Our ab-initio density functional theory (DFT)
+calculations show that a subtle reconstruction in the surface Niobium atoms
+gives rise to rows of 4-fold coordinated oxygen separated by regions of 3-fold
+coordinated oxygen. The 4-fold oxygen rows are determined to be the source of
+the nanocrystal pattern observed in STM, and the two chemical states of oxygen
+observed in core-level X-ray photoelectron spectroscopy (XPS) are ascribed to
+the 3-fold and 4-fold oxygens. Furthermore, we find excellent agreement between
+the DFT calculated electronic structure with scanning tunnelling spectroscopy
+and valence XPS measurements.",2311.01275v1
+2023-11-02,Going for Gold(-Standard): Attaining Coupled Cluster Accuracy in Oxide-Supported Nanoclusters,"Metal nanoclusters supported on oxide surfaces are widely-used catalysts that
+boasts sharply enhanced activity over their bulk, especially for the coinage
+metals: Au, Ag and Cu. These properties depend sensitively on the nanocluster
+structure, which are challenging to model with density functional theory (DFT)
+-- the workhorse modelling technique. Leveraging the recently developed SKZCAM
+protocol, we perform the first ever benchmark study of coinage metal structures
+on the MgO surface with coupled cluster theory [CCSD(T)] -- the gold-standard
+modelling technique. We investigate a comprehensive range of DFT models
+(exchange-correlation functional and dispersion correction) and our benchmarks
+reveal that none of the investigated models can accurately describe this
+system. We demonstrate that this arises from inadequate account of metal-metal
+interactions in the nanocluster and propose a high-level correction which
+provides reference accuracy at low cost. This forges a path towards studying
+larger systems, which we highlight by benchmarking Au$_{20}$ on MgO, a
+challenging system where DFT models have disagreed on its ground state
+structure.",2311.01426v1
+2023-11-13,Photochemical Upcycling of Ultrastrong Polyethylene Nanomembranes into Fibrous Carbon at Ambient Conditions,"The escalating global issue of plastic waste accumulation, specifically
+polyolefins, necessitates an urgent solution for upcycling these materials into
+beneficial compounds. Yet, achieving such upcycling without introducing carbon
+dioxide into the environment remains a formidable challenge. In this study, we
+demonstrate an eco-friendly approach for the photochemical conversion of
+ultrastrong, ultratransparent, and ultrathin polyethylene membrane into fibrous
+carbon nanomembrane at ambient conditions. The membrane was sputter-coated with
+platinum and cuprous oxide nanoparticles and exposed to simulated sunlight,
+resulting in a porous carbon membrane decorated with Pt nanoparticles. The new
+carbonized nanomembrane maintained the pristine membrane's morphology. The
+membrane exhibited high activity (2.11 mA/cm2) for electrochemical ethanol
+oxidation with stability over 1000 cycles. This work holds significance for
+sustainable plastic waste management and the design of new polyolefin materials
+in a circular economy.",2311.07023v2
+2023-11-18,Busting the Myth of Spontaneous Formation of H2O2 at the Air-Water Interface: Contributions of the Liquid-Solid Interface and Dissolved Oxygen Exposed,"Recent reports on the spontaneous formation of H2O2(aq) at the air-water
+interface and the solid-water interface have been sensational. The speculated
+mechanism at the air-water interface is based on instantaneous ultrahigh
+electric fields and the micro-scale of droplets, whereas the solid-water
+interface is speculated to be the site for oxidation of water (or hydroxide
+ions) and reduction of the solid surface. We utilized 1H-NMR spectroscopy to
+investigate the effects of the nebulizing gas, the dissolved oxygen content,
+and solid substrates on the H2O2(aq) formation (detection limit 50 nM).
+Experiments revealed that contrary to the sensational claims, the air-water
+interface is not the site for H2O2(aq) formation; instead, it is the
+solid-water interface where H2O2(aq) is formed during the reduction of
+dissolved oxygen and oxidation of the solid surface. Curiously, the tendencies
+of solid substrates towards forming H2O2(aq) follow the classic Galvanic
+series. This report advances the current understanding of aquatic chemistry and
+should be relevant to corrosion science, surface science, and electrochemistry.",2311.11133v1
+2023-11-22,Electron-phonon mediated superconductivity in R$_6$Ni$_5$O$_{12}$ nickel oxides,"Nickel oxide superconductors offer an alternative playground for
+understanding the formation of Cooper pairs in correlated materials such as the
+famous cuprates. By studying the La$_{n+1}$Ni$_n$O$_{2n+2}$ phase diagram on
+the basis of hybrid and spin-polarized density functional theory simulations,
+we reveal the existence of charge and bond ordered (CBO) insulating phases that
+are quenched by doping effects, ultimately resulting in a metallic phase at the
+$n=5$ member. Nevertheless, the phonons associated with the CBO identified in
+the phase diagram remain sufficiently large to mediate Cooper pairs in
+La$_6$Ni$_5$O$_{12}$, yielding a computed critical temperature between
+$T_c=11-19$ K consistent with the 13 K observed experimentally in
+Nd$_6$Ni$_5$O$_{12}$. Thus, in order to identify the superconducting mechanism,
+extracting the relevant instabilities in the doping phase diagram of
+superconductors appears critical.",2311.13674v1
+2023-11-27,Evolution of the surface atomic structure of multielement oxide films: curse or blessing?,"Atomically resolved scanning tunneling microscopy (STM) and x-ray
+photoelectron spectroscopy (XPS) are used to gain atomic-scale insights into
+the heteroepitaxy of lanthanum-strontium manganite (LSMO,
+La$_{1-x}$Sr$_x$MnO$_{3-{\delta}}$, $x$ $\approx$ 0.2) on SrTiO$_3$(110). LSMO
+is a perovskite oxide characterized by several composition-dependent surface
+reconstructions. The flexibility of the surface allows it to incorporate
+nonstoichiometries during growth, which result in composition-dependent surface
+atomic structures. This happens up to a critical point, where phase separation
+occurs, clusters rich in the excess cations form at the surface, and films show
+a rough morphology. To limit the nonstoichiometry introduced by non-optimal
+growth conditions, it proves useful to monitor the changes in surface atomic
+structures as a function of the PLD parameters and tune the latter accordingly.",2311.15700v1
+2023-11-29,Ferroelectric domain nucleation and switching pathways in hafnium oxide,"Nanoscale ferroelectrics that can be integrated into microelectronic
+fabrication processes are highly desirable for low-power computing and
+non-volatile memory devices. However, scalable novel ferroelectric materials,
+such as hafnium oxide (HfO2), remain in a state of development, and a clear
+understanding of the effects of relevant compositional and processing
+parameters to control their ferroelectric properties and the actual
+polarization switching mechanisms are still under investigation. One key
+fundamental knowledge gap is the polarization switching pathway in
+ferroelectric hafnia. To further our fundamental understanding of domain
+nucleation and switching, we have studied polarization switching pathways in
+HfO2-x thin films in real-time at the atomic scale using transmission electron
+microscopy. We employed differential phase contrast imaging that allows for the
+acquisition of both hafnium and oxygen atomic column signals and facilitates
+the observation of relative movement of atomic columns between both
+sublattices. Our results demonstrate that the switching pathway involves a
+transient tetragonal-like local structure, as oxygen ions shift in locations
+and remain within their parent hafnium polyhedra.",2311.17290v1
+2023-12-07,Confinement-Induced Isosymmetric Metal-Insulator Transition in Ultrathin Epitaxial V2O3 Films,"Dimensional confinement has shown to be an effective strategy to tune
+competing degrees of freedom in complex oxides. Here, we achieved atomic
+layered growth of trigonal vanadium sesquioxide (V2O3) by means of
+oxygen-assisted molecular beam epitaxy. This led to a series of high-quality
+epitaxial ultrathin V2O3 films down to unit cell thickness, enabling the study
+of the intrinsic electron correlations upon confinement. By electrical and
+optical measurements, we demonstrate a dimensional confinement-induced
+metal-insulator transition in these ultrathin films. We shed light on the
+Mott-Hubbard nature of this transition, revealing an abrupt vanishing of the
+quasiparticle weight as demonstrated by photoemission spectroscopy.
+Furthermore, we prove that dimensional confinement acts as an effective
+out-of-plane stress. This highlights the structural component of correlated
+oxides in a confined architecture, while opening an avenue to control both
+in-plane and out-of-plane lattice components by epitaxial strain and
+confinement, respectively.",2312.04425v1
+2023-12-09,Can silica nanoparticles improve lithium transport in polymer electrolytes?,"The question of if silica nanoparticles can enhance the ionic conductivity of
+a polymer electrolyte above its crystallization temperature has remained
+unclear for the two decades following the first experiments on these systems.
+We use Molecular Dynamics simulations to decipher the atomic scale mechanisms
+affecting the properties of LiTFSI-poly(ethylene oxide) electrolytes upon the
+addition of silica nanoparticles. At any ionic concentration, adding
+nanoparticles significantly decreases the conductivity. Most of this reduction
+can be simply accounted for by the diffusion equation, resulting from the fact
+that the space occupied by the nanoparticles is made inactive and unable to
+sustain ionic diffusion. We identify two distinct regimes, above and below a
+concentration threshold, corresponding to very different ionic distributions
+and coordination features of the various species. The lack of conductivity
+enhancement observed in the simulations supports the conclusions of some recent
+measurements, and disagrees with the earliest experimental reports on hybrid
+silica/polyethylene-oxide electrolytes.",2312.05681v2
+2023-12-14,Reducing strain fluctuations in quantum dot devices by gate-layer stacking,"Nanofabricated metal gate electrodes are commonly used to confine and control
+electrons in electrostatically defined quantum dots. However, these same gates
+impart a complicated strain geometry that affects the confinement potential and
+potentially impairs device functionality. Here we investigate strain-induced
+fluctuations of the potential energy in Si/SiGe heterostructures, caused by (i)
+lattice mismatch, (ii) materials-dependent thermal contraction, and (iii)
+deposition stress in the metal gates. By simulating different gate geometries,
+ranging from simple to realistically complicated, and including features like
+overlapping metal and oxide layers, we can explain most observed strain
+features. In particular, we show that strain-induced potential fluctuations can
+be suppressed by employing overlapping gates that cover the whole active
+region, when the oxide layers are thin. These results suggest that strain
+effects should not present a serious challenge to qubit uniformity when
+following simple design rules.",2312.09235v2
+2023-12-28,"Antiferroelectric Oxide Thin-Films: Fundamentals, Properties, and Applications","Antiferroelectrics have received blooming interests because of a wide range
+of potential applications in energy storage, solid-state cooling, thermal
+switch, transducer, actuation, and memory devices. Many of those applications
+are the most prospective in thin film form. The antiferroelectric ordering in
+thin films is highly sensitive to a rich set of factors, such as lattice
+strain, film thickness, surface and interface effects as well as film
+stoichiometry. To unlock the full potential of these materials and design
+high-quality thin films for functional devices, a comprehensive and systematic
+understanding of their behavior is essential. In conjunction with the necessary
+fundamental background of antiferroelectrics, we review recent progress on
+various antiferroelectric oxide thin films, the key parameters that trigger
+their phase transition and the device applications that rely on the robust
+responses to electric, thermal, and optical stimuli. Current challenges and
+future perspectives highlight new and emerging research directions in this
+field. It is hoped that this review can boost the development of
+antiferroelectric thin-film materials and device design, stimulating more
+researchers to explore the unknowns together.",2312.16806v1
+2023-12-29,Utilizing the Janus MoSSe surface polarization property in complementary metal-oxide-semiconductor field effect transistor design,"Janus transition metal dichalcogenides (JTMDs) have attracted much attention
+because of their outstanding electronic and optical properties. The additional
+out-of-plane dipole in JTMDs can form n- and p-like Ohmic contacts, and this
+may be used in device applications such as pin diodes and photovoltaic cells.
+In this study, we exploit this property to design n- and p-type
+metal-oxide-semiconductor field effect transistors (MOSFETs). First, we use
+density-functional theory calculations to study the inherent dipole field
+strength in the trilayer JTMD MoSSe. The intrinsic dipole of MoSSe causes band
+bending at both the metal/MoSSe and MoSSe/metal interfaces, resulting in
+electron and hole accumulation to form n- and p-type Ohmic contact regions. We
+incorporate this property into a 2D finite-element-based
+Poisson-drift-diffusion solver to perform simulations, on the basis of which we
+design complementary MOSFETs. Our results demonstrate that JTMDs can be used to
+make n- and p-MOSFETs in the same layer without the need for any extra doping.",2312.17594v2
+2024-01-04,Site-Specific Plan-view (S)TEM Sample Preparation from Thin Films using a Dual-Beam FIB-SEM,"Plan-view transmission electron microscopy (TEM) samples are key to
+understand the atomic structure and associated properties of materials along
+their growth orientation, especially for thin films that are stain-engineered
+onto different substrates for property tuning. In this work, we present a
+method to prepare high-quality plan-view samples for analytical STEM study from
+thin-films using a dual-beam focused ion beam scanning electron microscope
+(FIB-SEM) system. The samples were prepared from thin films of perovskite
+oxides and metal oxides ranging from 20-80 nm thicknesses, grown on different
+substrates using molecular beam epitaxy. A site-specific sample preparation
+from the area of interest is described, which includes sample attachment and
+thinning techniques to minimize damage to the final TEM samples. While
+optimized for the thin film-like geometry, this method can be extended to other
+site-specific plan-view samples from bulk materials. Aberration-corrected
+scanning (S)TEM was used to access the quality of the thin film in each sample.
+This enabled direct visualization of line defects in perovskite BaSnO3 and Ir
+particle formation and texturing in IrO2 films.",2401.02538v1
+2024-01-10,First-principles predictions of HfO$_2$-based ferroelectric superlattices,"The metastable nature of the ferroelectric phase of HfO$_2$ is a significant
+impediment to its industrial application as a functional ferroelectric
+material. In fact, no polar phases exist in the bulk phase diagram of HfO$_2$,
+which shows a dominant non-polar monoclinic ground state. As a consequence,
+ferroelectric orthorhombic HfO$_2$ needs to be kinetically stabilized. Here, we
+propose an alternative approach, demonstrating the feasibility of
+thermodynamically stabilizing polar HfO$_2$ in superlattices with other simple
+oxides. Using the composition and stacking direction of the superlattice as
+design parameters, we obtain heterostructures that can be fully polar, fully
+antipolar or mixed, with improved thermodynamic stability compared to the
+orthorhombic polar HfO$_2$ in bulk form. Our results suggest that combining
+HfO$_2$ with an oxide that does not have a monoclinic ground state generally
+drives the superlattice away from this non-polar phase, favoring the stability
+of the ferroelectric structures that minimize the elastic and electrostatic
+penalties. As such, these diverse and tunable superlattices hold promise for
+various applications in thin-film ferroelectric devices.",2401.05288v1
+2024-01-22,Towards reliable synthesis of superconducting infinite layer nickelate thin films by topochemical reduction,"Infinite layer nickelates provide a new route beyond copper oxides to address
+outstanding questions in the field of unconventional superconductivity.
+However, their synthesis poses considerable challenges, largely hindering
+experimental research on this new class of oxide superconductors. That
+synthesis is achieved in a two-step process that yields the most
+thermodynamically stable perovskite phase first, then the infinite-layer phase
+by topotactic reduction, the quality of the starting phase playing a crucial
+role. Here, we report on reliable synthesis of superconducting infinite-layer
+nickelate films after successive topochemical reductions of a parent perovskite
+phase with nearly optimal stoichiometry. Careful analysis of the transport
+properties of the incompletely reduced films reveals an improvement of the
+strange metal behaviour of their normal state resistivity over subsequent
+topochemical reductions, offering insight into the reduction process.",2401.12307v2
+2024-01-23,Understanding atom probe's analytical performance for iron oxides using correlation histograms and ab initio calculations,"Field evaporation from ionic or covalently bonded materials often leads to
+the emission of molecular ions. The metastability of these molecular ions,
+particularly under the influence of the intense electrostatic field (1010
+Vm-1), makes them prone to dissociation with or without an exchange of energy
+amongst them. These processes can affect the analytical performance of atom
+probe tomography (APT). For instance, neutral species formed through
+dissociation may not be detected at all or with a time of flight no longer
+related to their mass, causing their loss from the analysis. Here, we evaluated
+the changes in the measured composition of FeO, Fe2O3 and Fe3O4 across a wide
+range of analysis conditions. Possible dissociation reactions are predicted by
+density-functional theory (DFT) calculations considering the spin states of the
+molecules. The energetically favoured reactions are traced on to the multi-hit
+ion correlation histograms, to confirm their existence within experiments,
+using an automated Python-based routine. The detected reactions are carefully
+analysed to reflect upon the influence of these neutrals from dissociation
+reactions on the performance of APT for analysing iron oxides.",2401.12784v1
+2024-01-27,Corrosion resistance of a water-borne resin doped with graphene derivatives applied on galvanized steel,"The present work reports the effect of adding Graphene Oxide (GO) and reduced
+Graphene Oxide (rGO) in the corrosion protection provided by a water-borne
+resin applied on a galvanized steel substrate. Three concentrations, 0.05, 0.1
+and 0.15 (all wt%) were tested. The results were markedly affected not only by
+the concentration of particles but also by their nature. Although the zeta
+potential values suggested good dispersibility of the particles in the resin,
+certain aggregation was observed, mainly in rGO 0.1 wt% and rGO 0.15 wt%
+formulations. The electrochemical impedance spectroscopy (EIS) technique
+characterised the free films' transport properties. The results suggested that
+the aggregation strongly influenced the film morphology. The rGO 0.1 wt% and
+rGO 0.15 wt% formulations exhibited percolating pores that facilitated the
+electrolyte uptake through the films. The EIS technique was also used to study
+the protective performance of the films when applied to the metallic substrate.
+The results confirmed the harmful effect of the particle's aggregation. The
+results were interesting for the rGO 0.05 wt% system, which displayed
+long-lasting protection properties. This performance was explained considering
+its good barrier properties and the zinc surface passivation by the generation
+of zincite, ZnO.",2401.15410v1
+2024-01-29,Optimization of scandium oxide growth by high pressure sputtering on silicon,"This work demonstrates the viability of scandium oxide deposition on silicon
+by means of high pressure sputtering. Deposition pressure and radio frequency
+power are varied for optimization of the properties of the thin films and the
+ScOx-Si interface. The physical characterization was performed by ellipsometry,
+Fourier transform infrared spectroscopy, x-ray diffraction and transmission
+electron microscopy. Aluminum gate electrodes were evaporated for
+metal-insulator-semiconductor (MIS) fabrication. From the electrical
+characterization of the MIS devices, the density of interfacial defects is
+found to decrease with deposition pressure, showing a reduced plasma damage of
+the substrate surface for higher pressures. This is also supported by lower
+flatband voltage shifts in the capacitance versus voltage hysteresis curves.
+Sputtering at high pressures (above 100 Pa) reduces the interfacial SiOx
+formation, according to the infrared spectra. The growth rates decrease with
+deposition pressure, so a very accurate control of the layer thicknesses could
+be provided.",2401.16489v1
+2024-01-29,Two-step conversion of metal and metal oxide precursor films to 2D transition metal dichalcogenides and heterostructures,"From the laboratory to real-world applications, synthesis of two dimensional
+(2D) materials requires modular techniques to control morphology, structure,
+chemistry, and the plethora of exciting properties arising from these nanoscale
+materials. In this review, we explore one of the many available synthesis
+techniques; the extremely versatile two-step conversion (2SC) method. The 2SC
+technique relies on deposition of a metal or metal oxide film, followed by
+reaction with a chalcogen vapor at an elevated temperature, converting the
+precursor film to a crystalline transition metal dichalcogenide (TMD). Herein,
+we consider the variables at each step of the 2SC process including the impact
+of the precursor film material and deposition technique, the influence of gas
+composition and temperature during conversion, as well as other factors
+controlling high quality 2D TMD synthesis. We feature the specific advantages
+to the 2SC approach including deposition on diverse substrates, low temperature
+processing, orientation control, and heterostructure synthesis, among others.
+Finally, emergent opportunities that take advantage of the 2SC approach are
+discussed to include next generation electronics, sensing, and optoelectronic
+devices as well as catalysis for energy-related applications; spotlighting the
+great potential of the 2SC technique.",2401.16513v1
+2024-01-29,High Pressure Sputtering For Kigh-k Dielectric Deposition. Is It Worth Trying?,"Our research group studies the deposition of high permittivity dielectrics by
+a non-standard method: high-pressure sputtering. The dielectrics studied here
+are gadolinium scandate deposited from dielectric targets, and gadolinium oxide
+deposited from a metallic target, with an in situ plasma oxidation. The
+stoichiometric gadolinium scandate presents a slight permittivity boost after
+annealing, but with gadolinium-rich scandate (grown with an annealing of a
+nanolaminate) the dielectric shows a high effective permittivity of 21 and no
+noticeable SiO2 layer at the interface with Si. On the other hand, the stacks
+fabricated with the metallic Gd target have a SiO2 interface less than 0.7 nm
+thick that can be further reduced by scavenging with Ti gates. In fact, this
+scavenging effect is also demonstrated for the first time with indium phosphide
+substrates, obtaining a low capacitance equivalent thickness of only 2.1 nm.",2401.17331v1
+2024-01-29,Gadolinium scandate by high-pressure sputtering for future generations of high-k dielectrics,"Gd-rich gadolinium scandate (Gd2-xScxO3) was deposited by high-pressure
+sputtering on (100) silicon by alternating the deposition of lower than 0.5 nm
+thick films of its binary components: Sc2O3 and Gd2O3. The formation of the
+ternary oxide was observed after the thermal treatments, with a high increase
+in the effective permittivity of the dielectric (up to 21). The silicon
+diffuses into the Gd2-xScxO3 films, which show an amorphous character. After
+the annealing no interfacial silicon oxide is present. CHF-VG curves indicated
+low hysteresis (55 mV) and a density of interfacial defects of 6e11 eV-1 cm-2.",2402.00887v1
+2024-02-02,"Methanation of carbon dioxide over ceria-praseodymia promoted Ni-alumina catalysts. Influence of metal loading, promoter composition and alumina modifier","Two series of ceria-praseodymia promoted Ni-alumina catalysts were prepared
+from two different commercial modified alumina supports by the incipient
+wetness impregnation method in two successive steps.The resulting materials
+were characterized in terms of their physico-chemical properties. Furthermore,
+the as-prepared catalysts were tested for the CO2 methanation reaction. The
+influence of the nominal Ni loading, molar composition of the Ce-Pr mixed oxide
+promoter and alumina modifier on the catalytic performance was carefully
+analyzed. Among these three composition parameters, the alumina dopant and
+especially the Ni content appear to have by far a much more pronounced effect
+on both the CO2 conversion and CH4 selectivity as compared to the Ce-Pr mixed
+oxide composition.",2402.01394v1
+2024-02-12,Epsilon near zero metal oxide based spectrally selective reflectors,"Epsilon near zero (ENZ) materials can contribute significantly to the
+advancement of spectrally selective coatings aimed at enhancing efficient use
+of solar radiation and thermal energy management. Here, we demonstrate a
+subwavelength thick, multilayer optical coating that imparts a spectrally ""step
+function"" like reflectivity onto diverse surfaces, from stainless steel to
+glass, employing indium tin oxide as the key ENZ material. The coating,
+harnessing the ENZ and plasmonic properties of nominally nanostructured ITO
+along with ultrathin layers of Cr and Cr2O3 show 15% reflectivity over the
+visible to near-infrared and 80% reflectivity (and low emissivity) beyond a
+cut-in wavelength around 1500 nm, which is tunable in the infrared. A
+combination of simulations and experimental results are used to optimize the
+coating architecture and gain insights into the relevance of the components.
+The straightforward design with high thermal stability will find applications
+requiring passive cooling.",2402.07414v1
+2024-02-12,Resistive switching acceleration induced by thermal confinement,"Enhancing the switching speed of oxide-based memristive devices at a low
+voltage level is crucial for their use as non-volatile memory and their
+integration into emerging computing paradigms such as neuromorphic computing.
+Efforts to accelerate the switching speed often result in an energy tradeoff,
+leading to an increase of the minimum working voltage. In our study, we present
+an innovative solution: the introduction of a low thermal conductivity layer
+placed within the active electrode, which impedes the dissipation of heat
+generated during the switching process. The result is a notable acceleration in
+the switching speed of the memristive model system SrTiO$_{3}$ by a remarkable
+factor of 10$^{3}$, while preserving the integrity of the switching layer and
+the interfaces with the electrodes, rendering it adaptable to various
+filamentary memristive systems. The incorporation of HfO$_{2}$ or TaO$_{x}$ as
+heat-blocking layers not only streamlines the fabrication process, but also
+ensures compatibility with complementary metal-oxide-semiconductor technology.",2402.07603v1
+2024-02-12,Electrically tunable plasmonic metasurface as a matrix of nanoantennas,"We report the fabrication and characterization of a plasmonic metasurface
+comprising electrically contacted sub-wavelength gold dipole nanoantennas,
+conformally coated by a thin hafnia film, an indium tin oxide layer and a
+backside mirror, forming metal-oxide-semiconductor (MOS) capacitors, for use as
+an electrically-tunable reflectarray or metasurface. By voltage biasing the
+nanoantennas through metallic connectors and leveraging the carrier refraction
+effect in the MOS capacitors, our measurements demonstrate phase control in
+reflection over a range of about 30 degrees, with a constant magnitude of
+reflection coefficient of 0.5, and the absence of secondary lobes.
+Comprehensive electromagnetic and quantum carrier models of the structure are
+developed and are in excellent agreement with the measurements. The metasurface
+holds promise for use as an optical phased array.",2402.07805v2
+2024-02-15,Adaptive multi-spectral mimicking with 2D-material nanoresonator networks,"Active nanophotonic materials that can emulate and adapt between many
+different spectral profiles -- with high fidelity and over a broad bandwidth --
+could have a far-reaching impact, but are challenging to design due to a
+high-dimensional and complex design space. Here, we show that a metamaterial
+network of coupled 2D-material nanoresonators in graphene can adaptively match
+multiple complex absorption spectra via a set of input voltages. To design such
+networks, we develop a semi-analytical auto-differentiable dipole-coupled model
+that allows scalable optimization of high-dimensional networks with many
+elements and voltage signals. As a demonstration of multi-spectral capability,
+we design a single network capable of mimicking four spectral targets
+resembling select gases (nitric oxide, nitrogen dioxide, methane, nitrous
+oxide) with very high fidelity (${>}\,90\%$). Our results are relevant for the
+design of highly reconfigurable optical materials and platforms for
+applications in sensing, communication and display technology, and signature
+and thermal management.",2402.09681v1
+2024-02-19,Epitaxial rare-earth doped complex oxide thin films for infrared applications,"Rare earth dopants are one of the most extensively studied optical emission
+centers for a broad range of applications such as laser optoelectronics,
+sensing, lighting, and quantum information technologies due to their narrow
+optical linewidth and exceptional coherence properties. Epitaxial doped oxide
+thin films can serve as a promising and controlled host to investigate
+rare-earth dopants suitable for scalable quantum memories, on-chip lasers and
+amplifiers. Here, we report high-quality epitaxial thin films of Tm-doped
+CaZrO$_3$ grown by pulsed laser deposition for infrared optoelectronic and
+quantum memory applications. We perform extensive structural and chemical
+characterization to probe the crystallinity of the films and the doping
+behavior. Low temperature photoluminescence measurements show sharp radiative
+transitions in the short-wave infrared range of 1.75 - 2 \mu m.",2402.12358v1
+2024-02-20,Black brookite rich in oxygen vacancies as an active photocatalyst for CO2 conversion: experiments and first-principles calculations,"Photocatalytic CO2 conversion is a clean technology to deal with CO2
+emissions, and titanium oxide (TiO2) polymorphs are the most investigated
+photocatalysts for such an application. In this study, black TiO2 brookite is
+produced by a high-pressure torsion (HPT) method and employed as an active
+photocatalyst for CO2 conversion. Black brookite with a large concentration of
+lattice defects (vacancies, dislocations and grain boundaries) showed enhanced
+light absorbance, narrowed optical bandgap and diminished recombination rate of
+electrons and holes. The photocatalytic activity of the black oxide for CO2
+conversion was higher compared to commercial brookite and benchmark P25
+catalyst powders. First-principles calculations suggested that the presence of
+oxygen vacancies in black brookite is effective not only for reducing optical
+bandgap but also for providing active sites for the adsorption of CO2 on the
+surface of TiO2.",2402.12731v1
+2024-02-21,Enhanced Superconductivity in SrTiO$_3$-based Interfaces via Amorphous Al2O3 Capping,"Oxide interfaces feature unique two-dimensional (2D) electronic systems with
+diverse electronic properties such as tunable spin-orbit interaction and
+superconductivity. Conductivity emerges in these interfaces when the thickness
+of an epitaxial polar layer surpasses a critical value, leading to charge
+transfer to the interface. Here, we show that depositing amorphous alumina on
+top of the polar oxide can reduce the critical thickness and enhance the
+superconducting properties for the (111) and the (100) SrTiO$_3$-based
+interfaces. A detailed transmission electron microscopy analysis reveals that
+the enhancement of the superconducting properties is linked to the expansion of
+the LaAlO$_3$ lattice in a direction perpendicular to the interface. We propose
+that the increase in the superconducting critical temperature, Tc, is a result
+of epitaxial strain",2402.14051v1
+2024-03-01,Deciphering diffuse scattering with machine learning and the equivariant foundation model: The case of molten FeO,"Bridging the gap between diffuse x-ray or neutron scattering measurements and
+predicted structures derived from atom-atom pair potentials in disordered
+materials, has been a longstanding challenge in condensed matter physics. This
+perspective gives a brief overview of the traditional approaches employed over
+the past several decades. Namely, the use of approximate interatomic pair
+potentials that relate 3-dimensional structural models to the measured
+structure factor and its associated pair distribution function. The use of
+machine learned interatomic potentials has grown in the past few years, and has
+been particularly successful in the cases of ionic and oxide systems. Recent
+advances in large scale sampling, along with a direct integration of scattering
+measurements into the model development, has provided improved agreement
+between experiments and large-scale models calculated with quantum mechanical
+accuracy. However, details of local polyhedral bonding and connectivity in
+meta-stable disordered systems still require improvement. Here we leverage
+MACE-MP-0; a newly introduced equivariant foundation model and validate the
+results against high-quality experimental scattering data for the case of
+molten iron(II) oxide (FeO). These preliminary results suggest that the
+emerging foundation model has the potential to surpass the traditional
+limitations of classical interatomic potentials.",2403.00259v1
+2024-03-01,First-principles Investigation of Thermodynamic Properties of CrNbO4 and CrTaO4,"In the present study, the DFT+U method was employed to predict the
+thermodynamic properties of Cr2O3, Nb2O5, and Ta2O5. Results were benchmarked
+with experimental data showing high accuracy, except for the negative thermal
+expansion (NTE) of Nb2O5, which is attributed to its polymorphic complexity.
+Additionally, we extended our analysis to rutile-type oxides CrNbO4 and CrTaO4,
+examining their entropy and heat capacity at finite temperatures. CrNbO4
+displayed slightly higher entropy and heat capacity at high temperatures. The
+mean linear thermal expansion coefficients for CrNbO4 and CrTaO4 from 500 K to
+2000 K were predicted to be 6.00*10-6/K and 13.49*10-6/K, respectively,
+corroborating with DFT predictions and experimental evidence. Our research
+highlights the precision of the DFT+U and phonon methods in predicting the
+thermodynamic properties of oxide materials, offering insights into the design
+of corrosion-resistant materials.",2403.00705v1
+2024-03-11,Electrical Degradation in Dielectric and Piezoelectric Oxides: Review of Defect Chemistry and Associated Characterization Techniques,"The properties of dielectric and piezoelectric oxides are determined by their
+processing history, crystal structure, chemical composition, microstructure,
+dopants (or defect) distribution, and defect kinetics. These materials are
+essential in a diverse range of applications including aerospace, medical,
+military, transportation, power engineering, and communication, where they are
+used as ceramic discs, thick and thin films, multilayer devices, etc.
+Significant advances in understanding the materials, processing, properties,
+and reliability of these materials have led to their widespread use in consumer
+electronics, military, and aerospace applications. This review delves into
+electrical degradation in dielectrics and piezoelectrics, focusing on defect
+chemistry and key characterization techniques. It also provides a detailed
+discussion of various spectroscopic, microscopic, and electronic
+characterization techniques essential for analyzing defects and degradation
+mechanisms.",2403.06359v1
+2024-03-19,Unveiling the Reactivity of Oxygen and Ozone on C2N Monolayer: A First-Principles Study,"The process of environmental oxidation is pivotal in determining the physical
+and chemical properties of two-dimensional (2D) materials. Its impact holds
+great significance for the practical application of these materials in
+nanoscale devices functioning under ambient conditions. This study delves into
+the influence of O2 and O3 exposure on the structural and electronic
+characteristics of the C2N monolayer, focusing on the kinetics of adsorption
+and dissociation reactions. Employing first-principles density functional
+theory calculations alongside climbing image nudged elastic band calculations,
+we observe that the C2N monolayer exhibits resistance to oxidation and
+ozonation, evidenced by energy barriers of 0.05 eV and 0.56 eV, respectively.
+These processes are accompanied by the formation of epoxide (C-O-C) groups.
+Furthermore, the dissociation mechanism involves charge transfers from the
+monolayer to the molecules. Notably, the dissociated configurations demonstrate
+higher bandgaps compared to the pristine C2N monolayer, attributed to robust
+C-O hybridization. These findings suggest the robustness of C2N monolayers
+against oxygen/ozone exposures, ensuring stability for devices incorporating
+these materials.",2403.12454v1
+2024-03-21,Selective advantage of aerobic glycolysis over oxidative phosphorylation,"The utilization of glycolysis in aerobic conditions have been a subject of
+debate for more than a century. A hypothesis supported by previous data is that
+glycolysis has a higher rate of ATP production per protein mass and per
+occupied volume than oxidative phosphorylation (OxPhos). However, a recent work
+by Shen et al14 challenges previous estimates, reporting that OxPhos has a
+higher rate of ATP production per protein mass than glycolysis. Here I show
+that Shen et al14 make a key assumption that is a subject of debate: that the
+proteomic cost of OxPhos is limited to proteins in enzymes of OxPhos and the
+TCA cycle. I argue that an intact mitochondria is required for functional
+OxPhos and therefore the whole mitochondrial protein content should be included
+for the cost estimate of OxPhos. After doing so, glycolysis is the most
+efficient pathway per protein mass or per volume fraction.",2403.14741v1
+2024-03-25,Highly dispersed Ru nanoparticles anchored on NiAl layered double oxides catalyst for selective hydrodeoxygenation of vanillin,"The hydrodeoxygenation (HDO) of lignin-derived feedstocks into value-added
+chemicals with high efficiency and selectivity is desirable for the utilization
+of biomass resource. The complex oxygen-containing groups of lignin-derived
+substance result in the challenge of the low selectivity toward the required
+product. In this work, highly dispersed Ru nanoparticles anchored on Ni3Al1
+layered double oxides (LDOs) catalyst derived from NiAl layered double
+hydroxides (LDHs) with flower-shaped morphology was constructed by a simple
+deposition-reduction method. The introduction of LDHs-derived support can
+significantly impact the catalytic activity for the HDO of lignin-derived
+vanillin (VL) into 2-methoxy-4-methylphenol (MMP). The Ru/Ni3Al1-400 catalyst
+obtained complete conversion of VL and 94.2% yield of MMP at 130 {\deg}C in
+methanol solvent, much better than the catalysts without LDHs-derived support.
+The methanol solvent is beneficial for the conversion of reaction intermediate
+of vanillin alcohol (VA). Detailed characterization reveals that the existence
+of the enhanced metal-support interaction over Ru/Ni3Al1-400 and the easily
+accessible acid sites facilitate the production of MMP.",2403.16433v1
+2024-03-25,Recent Advances on Transition-Metal-Based Layered Double Hydroxides Nanosheets for Electrocatalytic Energy Conversion,"Transition-metal-based layered double hydroxides (TM-LDHs) nanosheets are
+promising electrocatalysts in the renewable electrochemical energy conversion
+system, which are regarded as alternatives to noble metal-based materials. In
+this review, recent advances on effective and facile strategies to rationally
+design TM-LDHs nanosheets as electrocatalysts, such as increasing the number of
+active sties, improving the utilization of active sites (atomic-scale
+catalysts), modulating the electron configurations, and controlling the lattice
+facets, are summarized and compared. Then, the utilization of these fabricated
+TM-LDHs nanosheets for oxygen evolution reaction, hydrogen evolution reaction,
+urea oxidation reaction, nitrogen reduction reaction, small molecule
+oxidations, and biomass derivatives upgrading is articulated through
+systematically discussing the corresponding fundamental design principles and
+reaction mechanism. Finally, the existing challenges in increasing the density
+of catalytically active sites and future prospects of TM-LDHs nanosheets-based
+electrocatalysts in each application are also commented.",2403.16461v1
+2024-03-29,Electrical double layer and capacitance of TiO2 electrolyte interfaces from first principles simulations,"The electrical double layer (EDL) at aqueous solution-metal oxide interfaces
+critically affects many fundamental processes in electrochemistry, geology and
+biology, yet understanding its microscopic structure is challenging for both
+theory and experiments. Here we employ ab initio-based machine learning
+potentials including long-range electrostatics in large-scale atomistic
+simulations of the EDL at the TiO2-electrolyte interface. Our simulations
+provide a molecular-scale picture of the EDL that demonstrates the limitations
+of standard mean-field models. We further develop a method to accurately
+calculate the electrostatic potential drop at the interface. The computed
+capacitance originating from the adsorbed charges and the potential drop agrees
+with experiments, supporting the reliability of our description of the EDL. The
+larger interfacial capacitance of basic relative to acidic solutions originates
+from the higher affinity of the cations for the oxide surface and gives rise to
+distinct charging mechanisms on negative and positive surfaces.",2404.00167v1
+2006-08-14,Thermal relaxation of magnetic clusters in amorphous Hf_{57}Fe_{43} alloy,"The magnetization processes in binary magnetic/nonmagnetic amorphous alloy
+Hf_{57}Fe_{43} are investigated by the detailed measurements of magnetic
+hysteresis loops, temperature dependence of magnetization, relaxation of
+magnetization and magnetic ac susceptibility, including a nonlinear term.
+Blocking of magnetic moments at lower temperatures is accompanied with the slow
+relaxation of magnetization and magnetic hysteresis loops. All of the observed
+properties are explained with the superparamagnetic behaviour of the single
+domain magnetic clusters inside the nonmagnetic host, their blocking by the
+anisotropy barriers and thermal fluctuation over the barriers accompanied by
+relaxation of magnetization. From magnetic viscosity analysis based on thermal
+relaxation over the anisotropy barriers it is found out that magnetic clusters
+occupy the characteristic volume from 25 up to 200 nm3 . The validity of the
+superparamagnetic model of Hf_{57}Fe_{43} is based on the concentration of iron
+in the Hf_{100-x}Fe_{43} system that is just below the threshold for the long
+range magnetic ordering. This work throws more light on magnetic behaviour of
+other amorphous alloys, too.",0608307v3
+2007-06-13,Nonlinear turbulent magnetic diffusion and effective drift velocity of large-scale magnetic field in a two-dimensional magnetohydrodynamic turbulence,"We study a nonlinear quenching of turbulent magnetic diffusion and effective
+drift velocity of large-scale magnetic field in a developed two-dimensional MHD
+turbulence at large magnetic Reynolds numbers. We show that transport of the
+mean-square magnetic potential strongly changes quenching of turbulent magnetic
+diffusion. In particularly, the catastrophic quenching of turbulent magnetic
+diffusion does not occur for the large-scale magnetic fields $B \gg B_{\rm eq}
+/ \sqrt{\rm Rm}$ when a divergence of the flux of the mean-square magnetic
+potential is not zero, where $B_{\rm eq}$ is the equipartition mean magnetic
+field determined by the turbulent kinetic energy and Rm is the magnetic
+Reynolds number. In this case the quenching of turbulent magnetic diffusion is
+independent of magnetic Reynolds number. The situation is similar to
+three-dimensional MHD turbulence at large magnetic Reynolds numbers whereby the
+catastrophic quenching of the alpha effect does not occur when a divergence of
+the flux of the small-scale magnetic helicity is not zero.",0706.1846v1
+2007-10-26,Magnetic fluctuations and formation of large-scale inhomogeneous magnetic structures in a turbulent convection,"Magnetic fluctuations generated by a tangling of the mean magnetic field by
+velocity fluctuations are studied in a developed turbulent convection with
+large magnetic Reynolds numbers. We show that the energy of magnetic
+fluctuations depends on magnetic Reynolds number only when the mean magnetic
+field is smaller than $B_{eq} / 4 Rm^{1/4}$, where $B_{eq}$ is the
+equipartition mean magnetic field determined by the turbulent kinetic energy
+and Rm is magnetic Reynolds number. Generation of magnetic fluctuations in a
+turbulent convection with a nonzero mean magnetic field results in a decrease
+of the total turbulent pressure and may cause formation of the large-scale
+inhomogeneous magnetic structures even in an originally uniform mean magnetic
+field. This effect is caused by a negative contribution of the turbulent
+convection to the effective mean Lorentz force. The inhomogeneous large-scale
+magnetic fields are formed due to the excitation of the large-scale
+instability. The energy for this instability is supplied by the small-scale
+turbulent convection. The discussed effects might be useful for understanding
+the origin of the solar nonuniform magnetic fields, e.g., sunspots.",0710.5052v1
+2013-11-18,"Fabrication, properties, and applications of flexible magnetic films","Flexible magnetic devices, i.e., magnetic devices fabricated on flexible
+substrates, are very attractive in application of detecting magnetic field in
+arbitrary surface, non-contact actuators, and microwave devices due to the
+stretchable, biocompatible, light-weight, portable, and low cost properties.
+Flexible magnetic films are essential for the realization of various
+functionalities of flexible magnetic devices. To give a comprehensive
+understanding for flexible magnetic films and related devices, we have reviewed
+recent advances in the studies of flexible magnetic films including fabrication
+methods, magnetic and transport properties of flexible magnetic films, and
+their applications in magnetic sensors, actuators, and microwave devices. Three
+typical methods were introduced to prepare the flexible magnetic films.
+Stretching or bending the flexible magnetic films offers a good way to apply
+mechanical strain on magnetic films, so that magnetic anisotropy, exchanged
+bias, coercivity, and magnetoresistance can be effectively manipulated.
+Finally, a series of examples were shown to demonstrate the great potential of
+flexible magnetic films for future applications.",1311.4318v1
+2021-10-31,Shape Programmable Magnetic Pixel Soft Robot,"Magnetic response soft robot realizes programmable shape regulation with the
+help of magnetic field and produces various actions. The shape control of
+magnetic soft robot is based on the magnetic anisotropy caused by the orderly
+distribution of magnetic particles in the elastic matrix. In the previous
+technologies, magnetic programming is coupled with the manufacturing process,
+and the orientation of magnetic particles cannot be modified, which brings
+restrictions to the design and use of magnetic soft robot. This paper presents
+a magnetic pixel robot with shape programmable function. By encapsulating
+NdFeB/gallium composites into silicone shell, a thermo-magnetic response
+functional film with lattice structure are fabricated. Basing on
+thermal-assisted magnetization technique, we realized the discrete
+magnetization region distribution on the film. Therefore, we proposed a
+magnetic coding technique to realize the mathematical response action design of
+software robot. Using these methods, we prepared several magnetic soft robots
+based on origami structure. The experiments show that the behavior mode of
+robot can be flexibly and repeatedly regulated by magnetic encoding technique.
+This work provides a basis for the programmed shape regulation and motion
+design of soft robot.",2111.00422v2
+2022-02-07,Magnetism of QCD matter and pion mass from tensor-type spin polarization and anomalous magnetic moment of quarks,"We investigate the magnetism of QCD matter and pion mass under magnetic field
+considering the contribution from the tensor-type spin polarization and the
+anomalous magnetic moment (AMM) of quarks. It is found that the tensor-type
+spin polarization (TSP) induces the magnetic catalysis of chiral condensate and
+diamagnetism (negative magnetic susceptibility) of quark matter at low
+temperature, both neutral and charged pion masses increase quickly with
+magnetic field in the case of TSP. The anomalous magnetic moment (AMM) of
+quarks induces magnetic inhibition and a magnetic dependent AMM causes inverse
+magnetic catalysis at finite temperature, and the neutral pion mass decreases
+with magnetic field while the charged pion mass shows nonmonotonic behavior
+with the magnetic field, which is qualitatively in agreement with lattice
+result. However, the magnetic susceptibility is positive at low temperature
+with AMM. In the current framework, our results show the irreconcilable
+contradiction between the diamagnetism and inverse magnetic catalysis.",2202.03226v1
+2022-10-06,Current-induced perpendicular effective magnetic field in magnetic heterostructures,"Generation of perpendicular effective magnetic field or perpendicular spins
+({\sigma}z) is central for the development of energy-efficient, scalable, and
+external-magnetic-field-free spintronic memory and computing technologies.
+Here, we report the first identification and the profound impacts of a
+significant effective perpendicular magnetic field that can arise from
+asymmetric current spreading within magnetic microstrips and Hall bars. This
+effective perpendicular magnetic field can exhibit all the three
+characteristics that have been widely assumed in the literature to ""signify""
+the presence of a flow of {\sigma}z, i.e., external-magnetic-field-free current
+switching of uniform perpendicular magnetization, a sin2{\phi}-dependent
+contribution in spin-torque ferromagnetic resonance signal of in-plane
+magnetization ({\phi} is the angle of the external magnetic field with respect
+to the current, and a {\phi}-independent but field-dependent contribution in
+the second harmonic Hall voltage of in-plane magnetization. This finding
+suggests that it is critical to include current spreading effects in the
+analyses of various spin polarizations and spin-orbit torques in magnetic
+heterostructure. Technologically, our results provide perpendicular effective
+magnetic field induced by asymmetric current spreading as a novel, universally
+accessible mechanism for efficient, scalable, and external-magnetic-field-free
+magnetization switching in memory and computing technologies.",2210.02916v1
+2010-03-09,MAGNETIC ANOMALY IN SUPERCONDUCTING FeSe,"Synthesis, electrical and magnetic characterization of superconducting
+FeSe0.85 compound is reported. An anomaly in the magnetization against
+temperature around 90K is observed. Magnetic characterization of a commercial
+compound with nominal FeSe stoichiometry is also presented. The overall
+magnetic behaviors as well as the magnetic anomaly in both compounds are
+discussed in terms of magnetic impurities and secondary phases. Keyword: A.
+Superconductors",1003.1966v1
+2011-05-19,Ultra-fast spin avalanches in crystals of molecular magnets in terms of magnetic detonation,"Recent experiments (Decelle et al., Phys. Rev. Lett. 102, 027203 (2009))
+discovered an ultra-fast regime of spin avalanches in crystals of magnetic
+magnets, which was three orders of magnitude faster than the traditionally
+studied magnetic deflagration. The new regime has been hypothetically
+identified as magnetic detonation. Here we demonstrate the possibility of
+magnetic detonation in the crystals, as a front consisting of a leading shock
+and a zone of Zeeman energy release. We study the dependence of the magnetic
+detonation parameters on the applied magnetic field. We find that the magnetic
+detonation speed only slightly exceeds the sound speed in agreement with the
+experimental observations.",1105.3962v1
+2013-07-18,Interaction effect detected by compared of the irreversible and remanent initial magnetization curves in Ni-Cu-Zn ferrites,"A new technique for estimation of magnetic interaction effects of initial
+magnetization curves has been proposed. It deals with remanence, and initial
+irreversible magnetization, curves. The method is applied for single-phase
+polycrystalline Ni0.85-xCu0.15ZnxFe2O4, (x = 0, 0.2, 0.4 and 0.6), which were
+synthesized by a standard ceramic technology. A study of the initial reversible
+and irreversible magnetization processes in ferrite materials was carried out.
+The field dependence of the irreversible, and reversible, magnetizations was
+determined by magnetic losses of minor hysteresis loops obtained from different
+points of an initial magnetization curve. The influence of Zn-substitutions in
+Ni-Cu ferrites over irreversible magnetization processes and interactions in
+magnetic systems has been analyzed.",1307.4881v1
+2013-10-15,Plasticity-Induced Magnetization in Amorphous Magnetic Solids,"Amorphous magnetic solids, like metallic glasses, exhibit a novel effect: the
+growth of magnetic order as a function of mechanical strain under athermal
+conditions in the presence of a magnetic field. The magnetic moment increases
+in steps whenever there is a plastic event. Thus plasticity induces the
+magnetic ordering, acting as the effective noise driving the system towards
+equilibrium. We present results of atomistic simulations of this effect in a
+model of a magnetic amorphous solid subjected to pure shear and a magnetic
+field. To elucidate the dependence on external strain and magnetic field we
+offer a mean-field theory that provides an adequate qualitative understanding
+of the observed phenomenon.",1310.3979v1
+2017-09-11,Magnetic order and phase transition in the iron oxysulfide La2O2Fe2OS2,"The Mott-insulating iron oxychalcogenides exhibit complex magnetic behaviour
+and we report here a neutron diffraction investigation into the magnetic
+ordering in La2O2Fe2OS2. This quaternary oxysulfide adopts the
+anti-Sr2MnO2Sb2-type structure and orders antiferromagnetically below TN = 105
+K. We consider both its long-range magnetic structure and its magnetic
+microstructure, and the onset of magnetic order. It adopts the multi-k vector
+""2k"" magnetic structure (k = (0.5 0 0.5) and k = (0 0.5 0.5) and has
+similarities with related iron oxychalcogenides, illustrating the robust nature
+of the ""2k"" magnetic structure.",1709.03323v1
+2022-12-07,Quark condensate and magnetic moment in a strong magnetic field,"This paper studies the quark condensate, magnetic moment, magnetic
+polarization, and magnetic susceptibility in a strong external magnetic field
+by employing the Dyson-Schwinger equations (DSE). The results show that these
+physical quantities as functions of the magnetic field. We note that the
+quark's spin polarizations are approximately proportional to the magnetic field
+magnitude. For comparison, we investigate the magnetic moments and
+susceptibility of the nucleon in the constituent quark model framework and
+demonstrate that both these quantities increase as the magnetic field rises.",2212.03508v2
+2023-12-26,Magnetic vortex control with current-induced axial magnetization in centrosymmetric Weyl materials,"We consider magnetic Weyl metals as a platform to achieve current control of
+magnetization textures with transport currents, utilizing their underlying band
+geometry. We show that the transport current in a Weyl semimetal produces an
+axial magnetization due to orbital magnetic moments of the Weyl electrons. The
+associated axial magnetization can generate a torque acting on the localized
+magnetic moments. For the case of a magnetic vortex in a nanodisk of Weyl
+materials, this current-induced torque can be used to reverse its circulation
+and polarity. We discuss the axial magnetization torques in Weyl metals on
+general symmetry grounds, and compare their strength to current-induced torques
+in more conventional materials.",2312.16122v1
+2004-09-08,Magnetic and electronic phase transformations in (Sm0.65Sr0.35)MnO3 induced by temperature and magnetic field,"Temperature (4.2-260 K) and magnetic field (0-50 kOe) dependencies of the dc
+electrical resistance, dc magnetization, and ac magnetic susceptibility of
+(Sm0.65Sr0.35)MnO3 prepared from high purity components have been studied.",0409213v1
+2008-02-20,Anomalous Magnetic Properties of Sr2YRuO6,"Anomalous magnetic properties of the double perovskite ruthenates compound
+Sr2YRuO6 are reported here. Magnetization measurements as a function of
+temperature in low magnetic fields show clear evidence for two components of
+magnetic order (TM1 ~ 32K and TM2 ~ 27K) aligned opposite to each other with
+respect to the magnetic field direction even though only Ru5+moments can order
+magnetically in this compound. The second component of the magnetic order at
+TM2 ~ 27K results only in a magnetization reversal, and not in the negative
+magnetization when the magnetization is measured in the field cooled (FC) mode.
+Isothermal magnetization (M-H) measurements show hysteresis with maximum
+coercivity (Hc) and remnant magnetization (Mr) at T ~ 27 K, corroborating the
+presence of the two oppositely aligned magnetic moments, each with a
+ferromagnetic component. The two components of magnetic ordering are further
+confirmed by the double peak structure in the heat capacity measurements. These
+anomalous properties have significance to some of the earlier results obtained
+for the Cu-substituted superconducting Sr2YRu1-xCuxO6 compounds.",0802.2953v2
+2014-09-05,"Analysis of the magnetic field, force, and torque for two-dimensional Halbach cylinders","The Halbach cylinder is a construction of permanent magnets used in
+applications such as nuclear magnetic resonance apparatus, accelerator magnets
+and magnetic cooling devices. In this paper the analytical expression for the
+magnetic vector potential, magnetic flux density and magnetic field for a two
+dimensional Halbach cylinder are derived. The remanent flux density of a
+Halbach magnet is characterized by the integer $p$. For a number of
+applications the force and torque between two concentric Halbach cylinders are
+important. These quantities are calculated and the force is shown to be zero
+except for the case where $p$ for the inner magnet is one minus $p$ for the
+outer magnet. Also the force is shown never to be balancing. The torque is
+shown to be zero unless the inner magnet $p$ is equal to minus the outer magnet
+$p$. Thus there can never be a force and a torque in the same system.",1409.1712v1
+2018-12-18,(Self-)Magnetized Bose-Einstein Condensate stars,"We study magnetic field effects on the Equations of State (EoS) and the
+structure of Bose-Einstein Condensate (BEC) stars, i.e. a compact object
+composed by a gas of interacting spin one bosons formed up by the pairing of
+two neutrons. To include the magnetic field in the thermodynamic description,
+we suppose that particle-magnetic field and particle-particle interactions are
+independent. We consider two configurations for the magnetic field: one where
+it constant and externally fixed, and another where it is produced by the
+bosons by self-magnetization. Since the magnetic field produces the splitting
+of pressures in the directions along and perpendicular to the magnetic axis,
+stable configurations of self-magnetized and magnetized BEC stars are studied
+using the recently found $\gamma$-structure equations that describe axially
+symmetric objects. The magnetized BEC stars are, in general spheroidal, less
+massive and smaller than the non-magnetic ones, being these effects more
+relevant at low densities. For the self-magnetized BEC stars their inner
+profiles of magnetic field can be computed as a function of the equatorial
+radii. The values obtained for the core and surface magnetic fields are in
+agreement with those typical of compact objects.",1812.07657v1
+2019-12-03,Internally-Balanced Magnetic Mechanisms Using Magnetic Spring for Producing Large Amplified Clamping Force,"To detach a permanent magnet with a controlled force much smaller than its
+original attractive force, the Internally-Balanced Magnetic Unit (IB Magnet)
+was invented and has been applied to magnetic devices such as wall-climbing
+robots, ceil-dangling drones, and modular swarm robots. In contrast to its
+drastic reduction rate on the control force, the IB Magnet has two major
+problems on its nonlinear spring which cancels out the internal force on the
+magnet: complicated design procedure and trade-off relationship between
+balancing precision and mechanism volume. This paper proposes a principle of a
+new balancing method for the IB Magnet which uses a like-pole pair of magnets
+as a magnetic spring, whose repulsive force ideally equals the attractive force
+of an unlike-pole pair exactly. To verify the proposed principle, the authors
+realized a prototype model of the IB Magnet using magnetic spring and verified
+through experiments its reduction rate is comparable to those of conventional
+IB Magnets. Moreover, the authors discussed and realized a robotic clamp as an
+application example containing proposed IB Magnets as its internal mechanism.",1912.01292v1
+2020-09-14,Voltage-driven Magnetization Switching via Dirac Magnetic Anisotropy and Spin--orbit Torque in Topological-insulator-based Magnetic Heterostructures,"Electric-field control of magnetization dynamics is fundamentally and
+technologically important for future spintronic devices. Here, based on
+electric-field control of both magnetic anisotropy and spin--orbit torque, two
+distinct methods are presented for switching the magnetization in topological
+insulator (TI)/magnetic-TI hybrid systems. The magnetic anisotropy energy in
+magnetic TIs is formulated analytically as a function of the Fermi energy, and
+it is confirmed that the out-of-plane magnetization is always favored for the
+partially occupied surface band. Also proposed is a transistor-like device with
+the functionality of a nonvolatile magnetic memory that uses voltage-driven
+writing and the (quantum) anomalous Hall effect for readout. For the
+magnetization reversal, by using parameters of Cr-doped
+Bi_{1-x}Sb_{x})_{2}Te_{3}, the estimated source-drain current density and gate
+voltage are of the orders of $10^4$--$10^5$~A/cm$^2$ and 0.1~V, respectively,
+below 20~K and the writing requires no external magnetic field. Also discussed
+is the possibility of magnetization switching by the proposed method in
+TI/ferromagnetic-insulator bilayers with the magnetic proximity effect.",2009.06187v1
+2021-07-10,Photoinduced Magnetic Force Microscopy: Enabling Direct and Exclusive Detection of Optical Magnetism,"Modern optical nano-elements pursue ever-smaller sizes and individualized
+functionalities. Those elements that can efficiently manipulate the magnetic
+field of light boast promising future applications with a great challenge: the
+magnetic near field is irretrievable from conventional optical far-field
+characterization. Here we propose photoinduced magnetic force microscopy to
+directly and exclusively sense the magnetic field of light at the nanoscale.
+The proposed instrument exploits a magnetic nanoprobe with exclusive magnetic
+excitation under structured light illumination. The magnetic nanoprobe detects
+the photoinduced magnetic force, which is defined as the dipolar Lorentz force
+exerted on the photoinduced magnetic dipole in the nanoprobe. Since the
+resulting magnetic force is proportional to the incident magnetic field, the
+measured force reveals the magnetic near-field distribution at the nanoscale.
+The proposed instrument represents a fundamental step towards comprehensive
+electric and magnetic near-field detection and/or manipulation in single
+nano-element optical devices.",2107.04739v1
+2022-08-31,Second-order phase transition of silicon from a band insulator to metal induced by strong magnetic fields,"We present the second-order phase transition from a band insulator to metal
+that is induced by a strong magnetic field. The magnetic-field dependences of
+the magnetization and energy band gap of a crystalline silicon immersed in a
+magnetic field are investigated by means of the nonperturbative
+magnetic-field-containing relativistic tight-binding approximation method
+[Phys. Rev. B 97, 195135 (2018)]. It is shown that the energy band gap
+disappears at the critical magnetic field of 2.22x$10^4$ (T). At the critical
+magnetic field, the magnetic-field dependence of the magnetization exhibits a
+kink behavior, which means that this phenomenon is the second-order phase
+transition from a band insulator to metal. It is found that in strong magnetic
+fields above the critical magnetic field, namely in the metallic phase, the
+oscillation of the magnetization appears. It is shown that this magnetic
+oscillation comes from the energy bands in the magnetic Brillouin zone that
+change from the occupied states to unoccupied states or vice vasa.",2208.14690v1
+2023-07-18,Yu-Shiba-Rusinov tips: imaging spins at the atomic scale with full magnetic sensitivity,"Measurements of magnetic properties at the atomic scale require probes
+capable of combining high spatial resolution with spin sensitivity.
+Spin-polarized scanning tunneling microscopy (SP-STM) fulfills these conditions
+by using atomically sharp magnetic tips. The imaging of spin structures results
+from the tunneling magneto-conductance that depends on the imbalance in the
+local density of spin-up and spin-down electrons. Spin-sensitive tips are
+generally formed from bulk materials or by coating non-magnetic tips with a
+thin magnetic layer. However, ferromagnetic materials generate stray magnetic
+fields which can influence the magnetic structure of the probed system, while
+the magnetization of antiferromagnetic materials is difficult to set tip by
+externally applied magnetic fields. Here, we use functionalized
+Yu-Shiba-Rusinov (YSR) tips prepared by attaching magnetic adatoms at the apex
+of a superconducting cluster to image magnetic interactions at the atomic
+scale. We demonstrate that YSR tips are capable of sensing different
+magnetization directions, conferring them full magnetic sensitivity. We
+additionally show that the finite size of the tip superconducting cluster makes
+it robust against relatively strong magnetic fields, making YSR tips capable of
+visualizing magnetic field driven transitions of the spin texture.",2307.09534v1
+2024-03-20,Molecular Dynamics Simulations of Microscopic Structural Transition and Macroscopic Mechanical Properties of Magnetic Gels,"Magnetic gels with embedded micro/nano-sized magnetic particles in
+crosslinked polymer networks can be actuated by external magnetic fields, with
+changes in their internal microscopic structures and macroscopic mechanical
+properties. We investigate the responses of such magnetic gels to an external
+magnetic field, by means of coarse-grained molecular dynamics simulations. We
+find that the dynamics of magnetic particles are determined by the interplay of
+between magnetic dipole-dipole interactions, polymer elasticity and thermal
+fluctuations. The corresponding microscopic structures formed by the magnetic
+particles such as elongated chains can be controlled by the external magnetic
+field. Furthermore, the magnetic gels can exhibit reinforced macroscopic
+mechanical properties, where the elastic modulus increases algebraically with
+the magnetic moments of the particles in the form of
+$\propto(m-m_{\mathrm{c}})^{2}$ when magnetic chains are formed. This
+simulation work can not only serve as a tool for studying the microscopic and
+the macroscopic responses of the magnetic gels, but also facilitate future
+fabrications and practical controls of magnetic composites with desired
+physical properties.",2403.13481v1
+2017-02-07,Characteristics of Low-Latitude Coronal Holes near the Maximum of Solar cycle 24,"We investigate the statistics of 288 low-latitude coronal holes extracted
+from SDO/AIA-193 filtergrams over the time range 2011/01/01 to 2013/12/31. We
+analyse the distribution of characteristic coronal hole properties, such as the
+areas, mean AIA-193 intensities, and mean magnetic field densities, the local
+distribution of the SDO/AIA-193 intensity and the magnetic field within the
+coronal holes, and the distribution of magnetic flux tubes in coronal holes. We
+find that the mean magnetic field density of all coronal holes under study is
+3.0 +- 1.6 G, and the percentage of unbalanced magnetic flux is 49 +- 16 %. The
+mean magnetic field density, the mean unsigned magnetic field density, and the
+percentage of unbalanced magnetic flux of coronal holes depend strongly
+pairwise on each other, with correlation coefficients cc > 0.92. Furthermore,
+we find that the unbalanced magnetic flux of the coronal holes is predominantly
+concentrated in magnetic flux tubes: 38 % (81 %) of the unbalanced magnetic
+flux of coronal holes arises from only 1 % (10 %) of the coronal hole area,
+clustered in magnetic flux tubes with field strengths > 50 G (10 G). The
+average magnetic field density and the unbalanced magnetic flux derived from
+the magnetic flux tubes correlate with the mean magnetic field density and the
+unbalanced magnetic flux of the overall coronal hole (cc > 0.93). These
+findings give evidence that the overall magnetic characteristics of coronal
+holes are governed by the characteristics of the magnetic flux tubes.",1702.02050v1
+2019-12-09,Field Dependence of Magnetic Disorder in Nanoparticles,"The performance characteristics of magnetic nanoparticles towards
+application, e.g. in medicine, imaging, or as sensors, is directly determined
+by their magnetization relaxation and total magnetic moment. In the commonly
+assumed picture, nanoparticles have a constant overall magnetic moment
+originating from the magnetization of the single-domain particle core
+surrounded by a surface region hosting spin disorder. In contrast, this work
+demonstrates the significant increase of the magnetic moment of ferrite
+nanoparticles with applied magnetic field. At low magnetic field, the
+homogeneously magnetized particle core initially coincides in size with the
+structurally coherent grain of 12.8(2) nm diameter, indicating a strong
+coupling between magnetic and structural disorder. Applied magnetic fields
+gradually polarize the uncorrelated, disordered surface spins, resulting in a
+magnetic volume more than 20\% larger than the structurally coherent core. The
+intraparticle magnetic disorder energy increases sharply towards the
+defect-rich surface as established by the field-dependence of the magnetization
+distribution. In consequence, these findings illustrate how the nanoparticle
+magnetization overcomes structural surface disorder. This new concept of
+intraparticle magnetization is deployable to other magnetic nanoparticle
+systems, where the in-depth knowledge of spin disorder and associated magnetic
+anisotropies will be decisive for a rational nanomaterials design.",1912.04081v2
+2021-04-23,Interesting magnetic response of the nuclear fuel material UO2,"Magnetic response of uranium dioxide (UO2) has been investigated through
+temperature and magnetic field dependent dc magnetization measurements. UO2 is
+a paramagnet at room temperature. The magnetic susceptibility, however,
+deviates from Curie-Weiss (CW) like paramagnetic behavior below T = 280 K.
+Further down the temperature UO2 undergoes phase transition to an
+antiferromagnetic state below TN = 30.6 K. The zero field cooled (ZFC) and
+field cooled (FC) magnetizations exhibit some distinct thermomagnetic
+irreversibility below TN. The temperature dependence of the FC magnetization is
+more like a ferromagnet, whereas ZFC magnetization exhibits distinct structures
+not usually observed in the antiferromagnets. In low applied magnetic field
+this thermomagnetic irreversibility in magnetization exists in a subtle way
+even in the paramagnetic regime above TN up to a fairly high temperature, but
+vanishes in high applied magnetic fields. Deviation from CW law and
+irreversibility between ZFC and FC magnetization indicate that the paramagnetic
+state above TN is not a trivial one. Magnetic response below TN changes
+significantly with the increase in the applied magnetic field. Thermomagnetic
+irreversibility in magnetization initially increases with the increase in the
+strength of applied magnetic field, but then gets reduced in the high applied
+fields. A subtle signature of a magnetic field induced phase transition is also
+observed in the isothermal magnetic field vartaion of magnetization. All these
+experimetal results highlight the non-trivial nature of the antiferromagnetic
+state in UO2",2104.11412v1
+1998-01-12,Persistent Currents and Magnetization in two-dimensional Magnetic Quantum Systems,"Persistent currents and magnetization are considered for a two-dimensional
+electron (or gas of electrons) coupled to various magnetic fields.
+Thermodynamic formulae for the magnetization and the persistent current are
+established and the ``classical'' relationship between current and
+magnetization is shown to hold for systems invariant both by translation and
+rotation. Applications are given, including the point vortex superposed to an
+homogeneous magnetic field, the quantum Hall geometry (an electric field and an
+homogeneous magnetic field) and the random magnetic impurity problem (a random
+distribution of point vortices).",9801106v1
+1999-03-20,Magnetism Controlled Vortex Matter,"We discuss a new class of phenomena based on strong interaction between
+magnetic superstructures and vortices in superconductors in combined
+heterogeneous structures. An inhomogeneous magnetization can pin vortices or
+create them spontaneously changing drastically properties of the
+superconductor. On the other hand, the interaction between magnetic moments
+mediated by vortices can result in specific types of magnetic ordering. The
+same interaction can create coupled magnetic-superconducting defects. We
+discuss possible experimental observation of magnetism controlled vortex matter
+in superconducting films with magnetic nanoscale dots or stripes and layered
+systems with alternating superconducting and magnetic layers.",9903312v1
+1999-04-07,Perpendicular transport and magnetization processes in magnetic multilayers with strongly and weakly coupled magnetic layers,"Within the framework of a two-band tight-binding model, we have performed
+calculations of giant magnetoresistance, exchange coupling and thermoelectric
+power (TEP) for a system consisting of three magnetic layers separated by two
+non-magnetic spacers with the first two magnetic layers strongly
+antiferromagnetically exchange-coupled. We have shown how does the GMR relate
+with the corresponding regions of magnetic structure phase diagrams and
+computed some relevant hysteresis loops, too. The GMR may take negative values
+for specific layers thicknesses, and the TEP reveals quite pronounced
+oscillations around a negative bias.",9904086v1
+1999-11-23,Magnetization-plateau state of the S=3/2 spin chain with single ion anisotropy,"We reexamine the numerical study of the magnetized state of the S=3/2 spin
+chain with single ion anisotropy D(> 0) for the magnetization M=M_{S}/3, where
+M_{S} is the saturation magnetization. We find at this magnetization that for
+D<D_{c1}=0.387 the system is critical and the magnetization plateau does not
+appear. For D > D_{c1}, the parameter region is divided into two parts D_{c1} <
+D < D_{c2}=0.943 and D_{c2} < D. In each region, the system is gapful and the
+M=M_{S}/3 magnetization plateau appears in the magnetization process. From our
+numerical calculation, the intermediate region D_{c1} < D < D_{c2} should be
+characterized by a magnetized valence-bond-solid state.",9911364v1
+2003-07-16,Magnetic moment of an electron gas on the surface of constant negative curvature,"The magnetic moment of an electron gas on the surface of constant negative
+curvature is investigated. It is shown that the surface curvature leads to the
+appearance of the region of the monotonic dependence $M(B)$ at low magnetic
+fields. At high magnetic fields, the dependence of the magnetic moment on a
+magnetic field is the oscillating one. The effect of the surface curvature is
+to increase the region of the monotonic dependence of the magnetic moment and
+to break the periodicity of oscillations of the magnetic moment as a function
+of an inverse magnetic field.",0307401v1
+2003-09-11,Giant Keplerate molecule Fe30 - the first octopole magnet,"The multipole expansion technique is applied to one of the largest magnetic
+molecules, Fe30. The molecule's dipole, toroid and quadrupole magnetic moments
+are equal to zero (in the absence of magnetic field) so the multipole expansion
+starts from the octopole moment. Probably the Fe30 molecule is the most
+symmetrical magnetic body synthesized so far. The magnetization process is
+considered theoretically in different geometries. Some components of the
+octopole moment experience a jump while the magnetization rises linearly up to
+its saturation value. An elementary octopole moment consisting of four magnetic
+dipoles is proposed as a hint for designing of an experiment for measurement of
+octopole magnetic moment components.",0309282v1
+2004-12-27,Magnetization suppression of Type-II Superconductors by external alternating magnetic field,"The effect of suppression of static magnetization of an anisotropic hard
+superconductor by alternating magnetic field is analyzed theoretically. The
+magnetic moment suppression dynamics is described with respect to the
+magnetization loop of the superconductor. It is found that in some cases the
+magnetic moment varies nonmonotonically with the growth in amplitude
+$\mathrm{h}$ of the alternating field. Effect of transition, induced by
+$\mathrm{\mathbf{h}}(t)$, of superconductor form paramagnetic into the
+diamagnetic state is considered. The amplitude of alternating magnetic field
+$\mathrm{h}_{c}(\delta,\vartheta)$ for which the complete suppression of the
+magnetization occurs is calculated as the function of anisotropy parameter
+$\delta$ and it orientation angle $\vartheta$ with respect to the
+crystallographic axes of the sample.",0412695v1
+2009-09-25,Probing punctual magnetic singularities during magnetization process in FePd films,"We report the use of Lorentz microscopy to observe the domain wall structure
+during the magnetization process in FePd thin foils. We have focused on the
+magnetic structure of domain walls of bubble-shaped magnetic domains near
+saturation. Regions are found along the domain walls where the magnetization
+abruptly reverses. Multiscale magnetic simulations shown that these regions are
+vertical Bloch lines (VBL) and the different bubble shapes observed are then
+related to the inner structure of the VBLs. We were thus able to probe the
+presence of magnetic singularities as small as Bloch points in the inner
+magnetization of the domain walls.",0909.4645v1
+2010-06-21,Dynamics of magnetic charges in artificial spin ice,"Artificial spin ice has been recently implemented in two-dimensional arrays
+of mesoscopic magnetic wires. We propose a theoretical model of magnetization
+dynamics in artificial spin ice under the action of an applied magnetic field.
+Magnetization reversal is mediated by domain walls carrying two units of
+magnetic charge. They are emitted by lattice junctions when the the local field
+exceeds a critical value $H_c$ required to pull apart magnetic charges of
+opposite sign. Positive feedback from Coulomb interactions between magnetic
+charges induces avalanches in magnetization reversal.",1006.4075v2
+2010-11-08,Neutrino magnetic moment in a magnetized plasma,"The contribution of a magnetized plasma to the neutrino magnetic moment is
+calculated. It is shown that only part of the additional neutrino energy in
+magnetized plasma connecting with its spin and magnetic field strength defines
+the neutrino magnetic moment. It is found that the presence of magnetized
+plasma does not lead to the considerable increase of the neutrino magnetic
+moment in contrast to the results presented in literature previously.",1011.1779v1
+2011-03-08,Permanent magnets including undulators and wigglers,"After a few historic remarks on magnetic materials we introduce the basic
+definitions related to permanent magnets. The magnetic properties of the most
+common materials are reviewed and the production processes are described.
+Measurement techniques for the characterization of macroscopic and microscopic
+properties of permanent magnets are presented. Field simulation techniques for
+permanent magnet devices are discussed. Today, permanent magnets are used in
+many fields. This article concentrates on the applications of permanent magnets
+in accelerators starting from dipoles and quadrupoles on to wigglers and
+undulators.",1103.1573v1
+2013-02-20,Non-magnetic doping induced magnetism in Li doped SnO2 nanoparticles,"We address the possibility of non-magnetic doping induced magnetism, in Li
+doped SnO2 nano-particles. The compounds have been prepared by solid state
+route at equilibrium and were found to be crystallized in single rutile phase.
+The magnetization measurements have shown that Li-doping induces magnetism in
+SnO2 for a particular range of Li concentration. However, for other Li
+concentrations, including pure SnO2, the samples exhibit diamagnetism. To
+investigate the possible origin of the induced magnetism, we have studied the
+variation of the magnetization as a function of the average nano-particle
+radius. Possible scenarios for the appearance of magnetism in these compounds
+are discussed.",1302.4869v1
+2013-12-04,Titan Magnetic Tail: Does its Configuration correspond to the Induced Magnetosphere?,"Magnetic field structure observed in numerous Cassini flybys in the region of
+Titan interaction with the corotating flow of Kronian magnetosheric plasma
+contradicts the classical picture of the ideal induced magnetosphere produced
+by the magnetic field line draping about the obstacle. Clear draping is
+observed only upstream the Titan, but not in the Titan magnetic wake. We
+consider the magnetic field tension downstream the Titan magnetic tail and show
+that the magnetic field direction is not consistent with the induced
+magnetosphere produced by magnetic field lines draping. We arrive at the
+conclusion that the mechanisms alternative to the induced magnetosphere
+formation should be considered for the Titan magnetic surrounding.",1401.3729v1
+2015-06-05,On the magnetization process of ferromagnetic materials,"The present article concludes that a ferromagnetic sample could be considered
+like a paramagnetic system where the role of magnetic moments plays magnetic
+domains. Based on this conclusion and taking into account presence of an
+anisotropic field the formula which describes magnetization dependence on the
+external magnetic field is derived. Expressions for a remanent magnetization
+and a coercive force are presented. The new parameter to characterize a
+magnetic stiffness of a material is introduced. A physical expression for a
+dynamic magnetic susceptibility as a function of material's characteristics,
+external magnetic field, and a temperature is given.",1506.01805v3
+2015-05-19,Electromagnetic acceleration of permanent magnets,"We consider the acceleration of the permanent magnets, consisting of
+neodymium iron boron by means of the running magnetic field gradient. It is
+shown that the specific magnetic moment per nucleon in neodymium iron boron is
+determined by the remained magnetization of the substance. The maximum
+accessable gradient of the magnetic field accelerating the permanent magnets is
+determined by the coercive force thirty kilogauss. For the neodymium iron boron
+magnets this gradient is equal to twenty kilogauss divided by one centimeter.
+The finite velocity of the magnets six kilometers per second, the length of
+acceleration is six hundred thirty-seven meters.",1508.04078v1
+2016-04-03,Soliton collisions in soft magnetic nanotube with uniaxial anisotropy,"The structure of stable magnetic solitons of various orders in soft magnetic
+nanotube with uniaxial magnetic anisotropy has been studied using numerical
+simulation. Solitons of even order are immobile in axially applied magnetic
+field. Odd solitons show decreased mobility with respect to that of head-to
+head domain wall. Solitons of various orders can participate in nanotube
+magnetization reversal process. Various coalescence and decomposition processes
+in soliton assembly are considered. It is shown that the general magnetization
+state of magnetic nanotube consists of chains of magnetic solitons of various
+orders.",1604.00614v1
+2017-01-15,Magnetic Catalysis in Antiferromagnetic Films,"We study the low-temperature behavior of antiferromagnets in two spatial
+dimensions that are subjected to a magnetic field oriented perpendicular to the
+staggered magnetization order parameter. The evaluation of the partition
+function is carried to two-loop order within the systematic effective
+Lagrangian technique. Low-temperature series that are valid in weak magnetic
+and staggered fields are derived for the pressure, staggered magnetization, and
+magnetization. Remarkably, at $T$=0, the staggered magnetization is enhanced by
+the magnetic field, implying that the phenomenon of magnetic catalysis also
+emerges in antiferromagnetic films.",1701.04085v1
+2023-05-26,"Practical Concepts for Design, Construction and Application of Halbach Magnets in Magnetic Resonance","This review is a compilation of relevant concepts in designing Halbach
+multipoles for magnetic resonance applications. The main focus is on providing
+practical guidelines to plan, design and build such magnets. Therefore,
+analytical equations are presented for estimating the magnetic field from ideal
+to realistic systems. Various strategies of homogenizing magnetic fields are
+discussed together with concepts of opening such magnets without force, or
+combining them for variable fields. Temperature compensation and other
+practical aspects are also reviewed. For magnetic resonance two polarities (di-
+and quadrupole) are of main interest, but higher polarities are also included.",2305.17227v2
+2023-08-24,Non-reciprocal coherent all-optical switching between magnetic multi-states,"We present experimental and computational findings of the laser-induced
+non-reciprocal motion of magnetization during ultrafast photo-magnetic
+switching in garnets. We found distinct coherent magnetization precession
+trajectories and switching times between four magnetization states, depending
+on both directions of the light linear polarization and initial magnetic state.
+As a fingerprint of the topological symmetry, the choice of the switching
+trajectory is governed by an interplay of the photo-magnetic torque and
+magnetic anisotropy. Our results open a plethora of possibilities for designing
+energy-efficient magnetization switching routes at arbitrary energy landscapes.",2308.12771v1
+2023-08-28,Revisiting the Wu-Yang approach to magnetic charge,"The Wu-Yang fiber bundle approach to magnetic charge has an overlooked
+feature -- a disk-like sheet current density and associated magnetic field at
+the equator where the Northern hemisphere and Southern hemisphere Dirac string
+vector potentials connect. This disk magnetic field plays a role similar to the
+Dirac string in the Dirac approach to magnetic charge. Placing an electric
+charge near the disk magnetic field gives rise to a non-zero field momentum.
+This implies that the Wu-Yang construction is not a true magnetic charge -- it
+is a Coulomb magnetic field plus a disk magnetic field and planar current
+density.",2308.14706v1
+2024-01-19,Modelling and dynamics of pendulum systems subjected to a nonstationary magnetic field,"The prepared doctoral dissertation focuses on studying dynamics of systems
+composed of magnetic pendulums subjected to a non-stationary magnetic field. A
+magnetic pendulum is a physical pendulum with a magnet attached to its end and
+is placed in an external magnetic field. The non-stationary external magnetic
+field is generated by an electric coil placed under the pendulum and powered by
+a time-varying current signal. The presented research mainly concerns the
+oscillations in one potential well of a single magnetic pendulum, as well as
+the control of the energy flow between two torsionally coupled magnetic
+pendulums.",2401.10594v1
+2024-04-09,"One-Dimensional Model for Coupled Flexural, Torsional and Extensional Motions of Elastic Beams with Embedded Point Magnets under Magnetic Fields","This paper establishes a one-dimensional theoretical model for an elastic
+beam with embedded point magnets in extensional, bending and torsional motions.
+The beam has a circular cross-section. The point magnets may be in the interior
+or at the ends of the beam. They are assumed to be small and rigid, and may be
+ferromagnetic with spontaneous magnetic moments that can change their
+directions with respect to the magnets. The model shows that the extensional,
+flexural and torsional motions of the beam may be coupled by the point magnets
+when an external magnetic field is applied. A few examples are given.
+Piezoelectric beams with point magnets are also discussed.",2404.06232v1
+1999-09-27,Topological Constraints on the Relaxation of Complex Magnetic Fields,"Newly emerging magnetic flux can show a complicated linked or interwoven
+topology of the magnetic field. The complexity of this linkage or knottedness
+of magnetic flux is related to the free energy stored in the magnetic field.
+Magnetic reconnection provides a process to release this energy on the time
+scale of the dynamics. At the same time it approximately conserves the total
+magnetic helicity. Therefore the conservation of total magnetic helicity is a
+crucial constraint for the relaxation of complex magnetic fields. However, the
+total magnetic helicity is only the first, most elementary, quantity of an
+infinite series of topological invariants of the magnetic field. All these
+invariants are strictly conserved in ideal magnetohydrodynamics. As an example
+a preliminary set of these invariants is derived. The relevance of these higher
+order invariants for the final state of relaxation under magnetic reconnection
+and their implications for the release of magnetic energy are discussed.",9909443v1
+2007-10-22,Observation of magnetization reversal and negative magnetization in a double perovskite compound Sr2YbRuO6,"Detailed magnetic properties of the compound Sr2YbRuO6 are presented here.
+The compound belongs to the family of double perovskites forming a monoclinic
+structure. Magnetization meas-urements reveal clear evidence for two components
+of magnetic ordering aligned opposite to each other, leading to a magnetization
+reversal, compensation temperature (T* = 34 K) and neg-ative magnetization at
+low temperatures and low magnetic fields. Heat capacity measurements
+corroborate the presence of two components in the magnetic ordering and a
+noticeable third anomaly at low temperatures (~15 K) which cannot be attributed
+the Schottky effect. The calcu-lated magnetic entropy is substantially lower
+than that expected for the ground states of the or-dered moments of Ru5+ and
+Yb3+, indicating the presence of large crystal field effects and/ or
+in-complete magnetic ordering and/or magnetic frustrations well above the
+magnetic ordering. An attempt is made to explain the magnetization reversal
+within the frameworks of available models.",0710.4043v3
+2008-05-21,Energetic Analysis of Magnetic Transitions in Ultra-small Nanoscopic Magnetic Rings,"In this article, we report on experimental and theoretical investigations of
+magnetic transitions in cobalt rings of size (diameter, width and thickness)
+comparable to the exchange length of cobalt. Magnetization measurements were
+performed for two sets of magnetic ring arrays: ultra-small magnetic rings
+(outer diameter 13 nm, inner diameter 5nm and thickness 5 nm) and small
+thin-walled magnetic rings (outer diameter 150 nm, width 5 nm and thickness 5
+nm). This is the first report on the fabrication and magnetic properties of
+such small rings. Our calculations suggest that if the magnetic ring's sizes
+are comparable to, or smaller than, the exchange length of the magnetic
+material, then only two magnetic states are important - the pure single domain
+state and the flux closure vortex state. The onion-shape magnetic state does
+not arise. Theoretical calculations are based on an energetic analysis of pure
+and slightly distorted single domain and flux closure vortex magnetic states.
+Based on the analytical calculations, a phase diagram is also derived for
+ultra-small ring structures exhibiting the region for vortex magnetic state
+formations as a function of material parameter.",0805.3191v2
+2010-01-29,Orbital magnetization of the electron gas on a two-dimensional kagome lattice under a perpendicular magnetic field,"The orbital magnetization of the electron gas on a two-dimensional kagome
+lattice under a perpendicular magnetic field is theoretically investigated. The
+interplay between the lattice geometry and magnetic field induce nontrivial
+$k$-space Chern invariant in the magnetic Brillouin zone, which turns to result
+in profound effects on the magnetization properties. We show that the
+Berry-phase term in the magnetization gives a paramagnetic contribution, while
+the conventional term brought about by the magnetic response of the magnetic
+Bloch bands produces a diamagnetic contribution. As a result, the superposition
+of these two components gives rise to a delicate oscillatory structure in the
+magnetization curve when varying the electron filling factor. The relationship
+between this oscillatory behavior and the Hofstadter energy spectrum is
+revealed by selectively discussing the magnetization and its two components at
+the commensurate fluxes of $f$=1/4, 1/3, and 1/6, respectively. In particular,
+we reveal as a typical example the fractal structure in the magnetic
+oscillations by tuning the commensurate flux around $f$=1/4. The
+finite-temperature effect on the magnetization is also discussed.",1001.5330v1
+2011-03-16,Magnetization Plateaus in the Spin-1/2 Kagome Antiferromagnets: Volborthite and Vesignieite,"The magnetization of two spin-1/2 kagome antiferromagnets, volborthite and
+vesignieite, has been measured in pulsed magnetic fields up to 68 T. A
+magnetization plateau is observed for each compound near the highest magnetic
+field. Magnetizations at saturation are approximately equal to 0.40Ms for both
+compounds, where Ms is the fully saturated magnetization, irrespective of a
+difference in the distortion of the kagome lattice between the two compounds.
+It should be noted that these values of magnetizations are significantly larger
+than Ms/3 predicted theoretically for the one-third magnetization plateau in
+the spin-1/2 kagome antiferromagnet. The excess magnetization over Ms/3 is
+nearly equal to the sum of the magnetizations gained at the second and third
+magnetization steps in volborthite, suggesting that there is a common origin
+for the excess magnetization and the magnetization steps.",1103.3116v1
+2014-10-08,An optimized magnet for magnetic refrigeration,"A magnet designed for use in a magnetic refrigeration device is presented.
+The magnet is designed by applying two general schemes for improving a magnet
+design to a concentric Halbach cylinder magnet design and dimensioning and
+segmenting this design in an optimum way followed by the construction of the
+actual magnet. The final design generates a peak value of 1.24 T, an average
+flux density of 0.9 T in a volume of 2 L using only 7.3 L of magnet, and has an
+average low flux density of 0.08 T also in a 2 L volume. The working point of
+all the permanent magnet blocks in the design is very close to the maximum
+energy density. The final design is characterized in terms of a performance
+parameter, and it is shown that it is one of the best performing magnet designs
+published for magnetic refrigeration.",1410.1987v1
+2018-02-08,Nonspecific biological effects of weak magnetic fields depend on molecular rotations,"The radical pair mechanism is a leading hypothesis in animal magnetic
+navigation. This mechanism associates the magnetic sense with the visual
+system, the radical pairs in cryptochromes of the eye retina being specialized
+magnetic receptors that modulate rhodopsin-mediated photoreception. There are
+also nonspecific magnetic effects in biology, which occur mostly by chance and
+originate from the interaction of weak magnetic fields with the magnetic
+moments dispersed all over the organism at the microscopic level. The radical
+pair mechanism cannot explain this type of response for many reasons. We have
+previously shown that the above interaction has a finite probability of
+resulting in an observable. Here, we develop our physical model of nonspecific
+magnetic effects for the case of magnetic moments located in rotating
+molecules. We generalize the results of recent experiments on gene expression
+in plants in a constant magnetic field, and show that the precession of the
+magnetic moments that reside on rotating molecules can be slowed relative to
+the immediate biophysical structures. In quantum mechanical language, the
+crossing of the quantum levels of magnetic moments conjointly with molecular
+rotations explain nonspecific magnetic effects and leads to magnetic
+field-dependences that are in good agreement with the experiment.",1802.02903v1
+2019-05-22,"Effect of doping of Co, Ni and Ga on magnetic and dielectric properties of layered perovskite multiferroic YBaCuFeO5","YBaCuFeO5 is one of the interesting multiferroic compounds, which exhibits
+magnetic ordering and dielectric anomaly above 200 K. Partial substitution of
+Fe with other magnetic and non-magnetic ion affects the magnetic and the
+structural properties of the system. We report detailed investigation of
+structural, magnetic and dielectric properties of YBaCuFe0.85M0.15O5 (M=Co, Ni
+and Ga). We observed that the partial replacement of Ni and Co in place of Fe,
+results in magnetic dilution and broadening of the magnetic transition and
+shifting towards lower temperature. The replacement of Fe with non-magnetic Ga
+also results in shifting of the magnetic transition to the lower temperature
+side. The observed dielectric relaxation behavior in these compounds is due to
+the charge carrier hoping. This study highlights the impacts of magnetic and
+non-magnetic doping at the magnetic site on magnetic and dielectric properties
+in layered perovskite compound YBaCuFeO5.",1905.08982v2
+2020-07-17,Unraveling nanoscale magnetic ordering in Fe3O4 nanoparticle assemblies via x-rays,": Understanding the correlations between magnetic nanoparticles is important
+for nanotechnologies, such as high-density magnetic recording and biomedical
+applications, where functionalized magnetic particles are used as contrast
+agents and for drug delivery. The ability to control the magnetic state of
+individual particles depends on the good knowledge of magnetic correlations
+between particles when assembled. Inaccessible via standard magnetometry
+techniques, nanoscale magnetic ordering in self-assemblies of Fe3O4
+nanoparticles is here unveiled via x-ray resonant magnetic scattering (XRMS).
+Measured throughout the magnetization process, the XRMS signal reveals
+size-dependent inter-particle magnetic correlations. Smaller (5 nm) particles
+show little magnetic correlation, even when tightly close-packed, yielding to
+mostly magnetic disorder in the absence of external field, which is
+characteristic of superparamagnetic behavior. In contrast, larger (11 nm)
+particles tend to be strongly correlated, yielding a mix of magnetic orders
+including ferromagnetic and anti-ferromagnetic orders. These strong magnetic
+correlations are present even when the particles are sparsely distributed.",2007.09226v1
+2016-12-28,"Magnetic structure of Cu2MnBO5 ludwigite: thermodynamic, magnetic properties and neutron diffraction study","We report on the thermodynamic, magnetic properties and the magnetic
+structure of ludwigite-type Cu2MnBO5. The specific heat, the low-field
+magnetization and the paramagnetic susceptibility were studied on a single
+crystal and combined with powder neutron diffraction data. The temperature
+dependence of the specific heat and the neutron diffraction pattern reveal a
+single magnetic phase transition at T=92 K, which corresponds to the magnetic
+ordering into a ferromagnetic phase. The cation distribution and the values and
+directions of magnetic moments of ions in different crystallographic sites are
+established. The magnetic moments of Cu2+ and Mn3+ ions occupying different
+magnetic sites in the ferrimagnetic phase are pairwise antiparallel and their
+directions do not coincide with the directions of the principal
+crystallographic axes.The small value of the magnetic moment of copper ions
+occupying site 2a is indicative of partial disordering of the magnetic moments
+on this site. The magnetization measurements show a strong temperature
+hysteresis of magnetization, which evidences for field-dependent transitions
+below the phase transition temperature.",1612.08805v1
+2019-11-08,Magnetic glassy state at low spin state of Co3+ in EuBaCo2O5+δ (δ = 0.47) cobaltite,"The magnetic glassy state is a fascinating phenomenon, which results from the
+kinetic arrest of the first order magnetic phase transition. Interesting
+properties, such as metastable magnetization and nonequilibrium magnetic
+phases, are naturally developed in the magnetic glassy state. Here, we report
+magnetic glass property in the low spin state of Co3+ in EuBaCo2O5+{\delta}
+({\delta} = 0.47) cobaltite at low temperature (T < 60 K). The measurements of
+magnetization under the cooling and heating in unequal fields, magnetization
+relaxation and thermal cycling of magnetization show the kinetic arrest of low
+magnetization state below 60 K. The kinetically arrested low temperature
+magnetic phase is further supported through the study of isothermal magnetic
+entropy, which shows the significant entropy change. The present results will
+open a new window to search the microscopic relation between the spin state
+transitions and the kinetic arrest induced magnetic glassy phenomena in complex
+materials.",1911.03258v1
+2021-12-02,Magnetic correction to the Anomalous Magnetic Moment of Electron,"We investigate the leading order correction of anomalous magnetic moment
+(AMM) to the electron in weak magnetic field and find that the magnetic
+correction is negative and magnetic field dependent, indicating a magnetic
+catalysis effect for the electron gas. In the laboratory to measure the $g-2$,
+the magnitude of the magnetic field $B$ is several $\mathrm{T}$,
+correspondingly the magnetic correction to the AMM of electron/muon is around
+$10^{-34}$/$10^{-42}$, therefore the magnetic correction can be safely
+neglected in current measurement. However, when the magnitude of the magnetic
+field strength is comparable with the electron mass, the magnetic correction of
+electron's AMM will become considerable. This general magnetic correction to
+charged fermion's AMM can be extended to study QCD matter under strong magnetic
+field.",2112.01051v1
+2022-08-07,Mixels: Fabricating Interfaces using Programmable Magnetic Pixels,"In this paper, we present Mixels, programmable magnetic pixels that can be
+rapidly fabricated using an electromagnetic printhead mounted on an
+off-the-shelve 3-axis CNC machine. The ability to program magnetic material
+pixel-wise with varying magnetic force enables Mixels to create new tangible,
+tactile, and haptic interfaces. To facilitate the creation of interactive
+objects with Mixels, we provide a user interface that lets users specify the
+high-level magnetic behavior and that then computes the underlying magnetic
+pixel assignments and fabrication instructions to program the magnetic surface.
+Our custom hardware add-on based on an electromagnetic printhead and hall
+effect sensor clips onto a standard 3-axis CNC machine and can both write and
+read magnetic pixel values from magnetic material. Our evaluation shows that
+our system can reliably program and read magnetic pixels of various strengths,
+that we can predict the behavior of two interacting magnetic surfaces before
+programming them, that our electromagnet is strong enough to create pixels that
+utilize the maximum magnetic strength of the material being programmed, and
+that this material remains magnetized when removed from the magnetic plotter.",2208.03804v1
+2006-02-02,Evolution of Rotating Molecular Cloud Core with Oblique Magnetic Field,"We studied the collapse of rotating molecular cloud cores with inclined
+magnetic fields, based on three-dimensional numerical simulations.The numerical
+simulations start from a rotating Bonnor-Ebert isothermal cloud in a uniform
+magnetic field. The magnetic field is initially taken to be inclined from the
+rotation axis. As the cloud collapses, the magnetic field and rotation axis
+change their directions. When the rotation is slow and the magnetic field is
+relatively strong, the direction of the rotation axis changes to align with the
+magnetic field, as shown earlier by Matsumoto & Tomisaka. When the magnetic
+field is weak and the rotation is relatively fast, the magnetic field inclines
+to become perpendicular to the rotation axis. In other words, the evolution of
+the magnetic field and rotation axis depends on the relative strength of the
+rotation and magnetic field. Magnetic braking acts to align the rotation axis
+and magnetic field, while the rotation causes the magnetic field to incline
+through dynamo action. The latter effect dominates the former when the ratio of
+the angular velocity to the magnetic field is larger than a critical value
+\Omega_0/ B_0 > 0.39 G^1/2 c_s^-1, where B_0, \Omega_0, G, and c_s^-1 denote
+the initial magnetic field, initial angular velocity, gravitational constant,
+and sound speed, respectively. When the rotation is relatively strong, the
+collapsing cloud forms a disk perpendicular to the rotation axis and the
+magnetic field becomes nearly parallel to the disk surface in the high density
+region. A spiral structure appears due to the rotation and the wound-up
+magnetic field in the disk.",0602034v1
+2017-02-06,The formation of magnetic depletions and flux annihilation due to reconnection in the heliosheath,"The misalignment of the solar rotation axis and the magnetic axis of the Sun
+produces a periodic reversal of the Parker spiral magnetic field and the
+sectored solar wind. The compression of the sectors is expected to lead to
+reconnection in the heliosheath (HS). We present particle-in-cell simulations
+of the sectored HS that reflect the plasma environment along the Voyager 1 and
+2 trajectories, specifically including unequal positive and negative azimuthal
+magnetic flux as seen in the Voyager data \citep{Burlaga03}. Reconnection
+proceeds on individual current sheets until islands on adjacent current layers
+merge. At late time bands of the dominant flux survive, separated by bands of
+deep magnetic field depletion. The ambient plasma pressure supports the strong
+magnetic pressure variation so that pressure is anti-correlated with magnetic
+field strength. There is little variation in the magnetic field direction
+across the boundaries of the magnetic depressions. At irregular intervals
+within the magnetic depressions are long-lived pairs of magnetic islands where
+the magnetic field direction reverses so that spacecraft data would reveal
+sharp magnetic field depressions with only occasional crossings with jumps in
+magnetic field direction. This is typical of the magnetic field data from the
+Voyager spacecraft \citep{Burlaga11,Burlaga16}. Voyager 2 data reveals that
+fluctuations in the density and magnetic field strength are anti-correlated in
+the sector zone as expected from reconnection but not in unipolar regions. The
+consequence of the annihilation of subdominant flux is a sharp reduction in the
+""number of sectors"" and a loss in magnetic flux as documented from the Voyager
+1 magnetic field and flow data \citep{Richardson13}.",1702.01697v1
+2020-07-23,Signal Enhancement for Magnetic Navigation Challenge Problem,"Harnessing the magnetic field of the Earth for navigation has shown promise
+as a viable alternative to other navigation systems. A magnetic navigation
+system collects its own magnetic field data using a magnetometer and uses
+magnetic anomaly maps to determine the current location. The greatest challenge
+with magnetic navigation arises when the magnetic field measurements from the
+magnetometer encompass the magnetic field from not just the Earth, but also
+from the vehicle on which it is mounted. It is difficult to separate the Earth
+magnetic anomaly field, which is crucial for navigation, from the total
+magnetic field reading from the sensor. The purpose of this challenge problem
+is to decouple the Earth and aircraft magnetic signals in order to derive a
+clean signal from which to perform magnetic navigation. Baseline testing on the
+dataset has shown that the Earth magnetic field can be extracted from the total
+magnetic field using machine learning (ML). The challenge is to remove the
+aircraft magnetic field from the total magnetic field using a trained model.
+This challenge offers an opportunity to construct an effective model for
+removing the aircraft magnetic field from the dataset by using a scientific
+machine learning (SciML) approach comprised of an ML algorithm integrated with
+the physics of magnetic navigation.",2007.12158v2
+2023-04-13,High-performance descriptor for magnetic materials: Accurate discrimination of magnetic structure,"The magnetic structure is crucial in determining the physical properties
+inherent in magnetic compounds. We present an adequate descriptor for magnetic
+structure with proper magnetic symmetry and high discrimination performance,
+which does not depend on artificial choices for coordinate origin, axis, and
+magnetic unit cell in crystal. We extend the formalism called ``smooth overlap
+of atomic positions'' (SOAP), providing a numerical representation of atomic
+configurations to that of magnetic moment configurations. We introduce the
+descriptor in terms of the vector spherical harmonics to describe a magnetic
+moment configuration and partial spectra from the expansion coefficients. We
+discuss that the lowest-order partial spectrum is insufficient to discriminate
+the magnetic structures with different magnetic anisotropy, and a higher-order
+partial spectrum is required in general to differentiate detailed magnetic
+structures on the same atomic configuration. We then introduce the fourth-order
+partial spectrum and evaluate the discrimination performance for different
+magnetic structures, mainly focusing on the difference in magnetic symmetry.
+The modified partial spectra that are defined not to reflect the difference of
+magnetic anisotropy are also useful in evaluating magnetic structures obtained
+from the first-principles calculations performed without spin-orbit coupling.
+We apply the present method to the symmetry-classified magnetic structures for
+the crystals of Mn$_3$Ir and Mn$_3$Sn, which are known to exhibit anomalous
+transport under the antiferromagnetic order, and examine the discrimination
+performance of the descriptor for different magnetic structures on the same
+crystal.",2304.06282v2
+2023-08-25,Coexistence of non-trivial van der Waals magnetic orders enable field-free spin-orbit torque switching at room temperature,"The discovery of van der Waals (vdW) materials exhibiting non-trivial and
+tunable magnetic interactions at room temperature can give rise to exotic
+magnetic states, which are not readily attainable with conventional materials.
+Such vdW magnets can provide a unique platform for studying new magnetic
+phenomena and realising magnetization dynamics for energy-efficient and
+non-volatile spintronic memory and logic technologies. Recent developments in
+vdW magnets have revealed their potential to enable spin-orbit torque (SOT)
+induced magnetization dynamics. However, the deterministic and field-free SOT
+switching of vdW magnets at room temperature has been lacking, prohibiting
+their potential applications. Here, we demonstrate magnetic field-free and
+deterministic SOT switching of a vdW magnet (Co0.5Fe0.5)5GeTe2 (CFGT) at room
+temperature, capitalizing on its non-trivial intrinsic magnetic ordering. We
+discover a coexistence of ferromagnetic and antiferromagnetic orders in CFGT at
+room temperature, inducing an intrinsic exchange bias and canted perpendicular
+magnetism. The resulting canted perpendicular magnetization of CFGT introduces
+symmetry breaking, facilitating successful magnetic field-free magnetization
+switching in the CFGT/Pt heterostructure devices. Furthermore, the SOT-induced
+magnetization dynamics and their efficiency are evaluated using 2nd harmonic
+Hall measurements. This advancement opens new avenues for investigating tunable
+magnetic phenomena in vdW material heterostructures and realizing field-free
+SOT-based spintronic technologies.",2308.13408v1
+2006-09-08,Potential of Ozone Formation by the Smog Mechanism to shield the surface of the Early Earth from UV radiation?,"We propose that the photochemical smog mechanism produced substantial ozone
+(O3) in the troposphere during the Proterozoic, which contributed to
+ultraviolet (UV) radiation shielding hence favoured the establishment of life.
+The smog mechanism is well-established and is associated with pollution hazes
+which sometimes cover modern cities. The mechanism proceeds via the oxidation
+of volatile organic compounds (VOCs) such as methane (CH4) in the presence of
+UV radiation and nitrogen oxides (NOx). It would have been particularly
+favoured during the Proterozoic given the high levels of CH4 (up to 1000 ppm)
+recently suggested. Proterozoic UV levels on the surface of the Earth were
+generally higher compared with today, which would also have favoured the
+mechanism. On the other hand, Proterozoic O2 required in the final step of the
+smog mechanism to form O3 was less abundant compared with present times.
+Further, results are sensitive to Proterozoic NOx concentrations, which are
+challenging to predict, since they depend on uncertain quantities such as NOx
+source emissions and OH concentrations. We review NOx sources during the
+Proterozoic and apply a photochemical box model having methane oxidation with
+NOx, HOx and Ox chemistry to estimate the O3 production from the smog
+mechanism. Runs suggest the smog mechanism during the Proterozoic can produce
+about double present day ozone columns for NOx levels of 1.53 10-9 by volume
+mixing ratio, which was attainable according to our NOx source analysis, with 1
+per-cent present atmospheric levels (PALs) of O2. Clearly, forming ozone in the
+troposphere is a trade-off for survivability. On the one hand harmful UV is
+blocked, but on the other hand ozone is a respiratory irratant, which becomes
+fatal at concentrations exceeding about 1 ppmv.",0609219v1
+2007-01-30,A Search for Propylene Oxide and Glycine in Sagittarius B2 (LMH) and Orion,"We have used the Mopra Telescope to search for glycine and the simple chiral
+molecule propylene oxide in the Sgr B2 (LMH) and Orion KL, in the 3-mm band. We
+have not detected either species, but have been able to put sensitive upper
+limits on the abundances of both molecules. The 3-sigma upper limits derived
+for glycine conformer I are 3.7 x 10^{14} cm^{-2} in both Orion-KL and Sgr B2
+(LMH), comparable to the reported detections of conformer I by Kuan et al.
+However, as our values are 3-sigma upper limits rather than detections we
+conclude that this weighs against confirming the detection of Kuan et al. We
+find upper limits for the glycine II column density of 7.7 x 10^{12} cm^{-2} in
+both Orion-KL and Sgr B2 (LMH), in agreement with the results of Combes et al.
+The results presented here show that glycine conformer II is not present in the
+extended gas at the levels detected by Kuan et al. for conformer I. Our ATCA
+results (Jones et al.) have ruled out the detection of glycine (both conformers
+I and II) in the compact hot core of the LMH at the levels reported, so we
+conclude that it is unlikely that Kuan et al. have detected glycine in either
+Sgr B2 or Orion-KL. We find upper limits for propylene oxide abundance of 3.0 x
+10^{14} cm^{-2} in Orion-KL and 6.7 x 10^{14} cm^{-2} in Sgr B2 (LMH). We have
+detected fourteen features in Sgr B2 and four features in Orion-KL which have
+not previously been reported in the ISM, but have not be able to plausibly
+assign these transitions to any carrier.",0701866v1
+2002-01-28,"Fracton pairing mechanism for ""strange"" superconductors: Self-assembling organic polymers and copper-oxide compounds","Self-assembling organic polymers and copper-oxide compounds are two classes
+of ""strange"" superconductors, whose challenging behavior does not comply with
+the traditional picture of Bardeen, Cooper, and Schrieffer (BCS)
+superconductivity in regular crystals. In this paper, we propose a theoretical
+model that accounts for the strange superconducting properties of either class
+of the materials. These properties are considered as interconnected
+manifestations of the same phenomenon: We argue that superconductivity occurs
+in the both cases because the charge carriers (i.e., electrons or holes)
+exchange {\it fracton excitations}, quantum oscillations of fractal lattices
+that mimic the complex microscopic organization of the strange superconductors.
+For the copper oxides, the superconducting transition temperature $T_c$ as
+predicted by the fracton mechanism is of the order of $\sim 150$ K. We suggest
+that the marginal ingredient of the high-temperature superconducting phase is
+provided by fracton coupled holes that condensate in the conducting
+copper-oxygen planes owing to the intrinsic field-effect-transistor
+configuration of the cuprate compounds. For the gate-induced superconducting
+phase in the electron-doped polymers, we simultaneously find a rather modest
+transition temperature of $\sim (2-3)$ K owing to the limitations imposed by
+the electron tunneling processes on a fractal geometry. We speculate that
+hole-type superconductivity observes larger onset temperatures when compared to
+its electron-type counterpart. This promises an intriguing possibility of the
+high-temperature superconducting states in hole-doped complex materials. A
+specific prediction of the present study is universality of ac conduction for
+$T\gtrsim T_c$.",0201504v3
+2004-07-13,Multi-Dot Floating-Gates for Nonvolatile Semiconductor Memories - Their Ion Beam Synthesis and Morphology,"Scalability and performance of current flash memories can be improved
+substantially by replacing the floating poly-Si gate by a layer of Si dots.
+This multi-dot layer can be fabricated CMOS-compatibly in very thin gate oxide
+by ion beam synthesis (IBS). Here, we present both experimental and theoretical
+studies on IBS of multi-dot layers consisting of Si nanocrystals (NCs). The NCs
+are produced by ultra low energy Si ion implantation, which causes a high Si
+supersaturation in the shallow implantation region. During post-implantation
+annealing, this supersaturation leads to phase separation of the excess Si from
+the SiO2. Till now, the study of this phase separation process suffered from
+the weak Z contrast between Si and SiO2 in Transmission Electron Microscopy
+(TEM). Here, this imaging problem is resolved by mapping Si plasmon losses with
+a Scanning Transmission Electron Microscopy equipped with a parallel Electron
+Energy Loss Spectroscopy system (PEELS-STEM). Additionally, kinetic lattice
+Monte Carlo simulations of Si phase separation have been performed and compared
+with the experimental Si plasmon maps. It has been predicted theoretically that
+the morphology of the multi-dot Si floating-gate changes with increasing ion
+fluence from isolated, spherical NCs to percolated spinodal Si pattern. These
+patterns agree remarkably with PEELS-STEM images. However, the predicted
+fluence for spinodal patterns is lower than the experimental one. Because
+oxidants of the ambient atmosphere penetrate into the as-implanted SiO2, a
+substantial fraction of the implanted Si might be lost due to oxidation.",0407329v1
+2004-08-26,Ultrathin Organic Transistors on Oxide Surfaces,"In recent years, thin-film organic field-effect transistors (OFETs) have
+begun to be considered as a possible alternative to the hydrogenated amorphous
+silicon thin-film transistors (a-Si:H TFT's) used in active matrix flat panel
+displays and other large-area electronics applications. Low-temperature
+processability, low-cost fabrication and compatibility with arbitrary
+substrates are some of the promising advantages of OFETs, among others. Of the
+many organic materials available, pentacene, in particular, is one of the
+leading candidates for use in current thin-film OFET architectures - this
+because of its excellent electrical characteristics and its resistance to
+atmospheric oxygen. In the recent literature, pentacene's transport properties,
+as well as transistor performance, have already been analyzed from the point of
+view of substrate treatments, pentacene evaporation rate and substrate
+temperature, electrode chemical nature and channel geometry. The results show
+that the morphology, crystal structure and molecular ordering of the first
+organic monolayer(s) at the pentacene/dielectric interface are essential
+determinants of carrier transport phenomena. To further investigate these
+interface effects, we have built a model organic field-effect transistor which
+consists essentially of a single layer of pentacene on an oxide substrate.
+Four-probe and two-probe transport measurements as a function of temperature
+and fields will be presented in relation with structural near-field
+observations. The experimental results suggest a simple two-dimensional model
+where the equilibrium between free and trapped carriers at the oxide interface
+determines the OFET characteristics and performance.",0408562v2
+2006-11-24,High expression of antioxidant proteins in dendritic cells: possible implications in atherosclerosis,"Dendritic cells (DCs) display the unique ability to activate naive T cells
+and to initiate primary T cell responses revealed in DC-T cell alloreactions.
+DCs frequently operate under stress conditions. Oxidative stress enhances the
+production of inflammatory cytokines by DCs. We performed a proteomic analysis
+to see which major changes occur, at the protein expression level, during DC
+differentiation and maturation. Comparative two-dimensional gel analysis of the
+monocyte, immature DC, and mature DC stages was performed. Manganese superoxide
+dismutase (Mn-SOD) reached 0.7% of the gel-displayed proteins at the mature DC
+stage. This important amount of Mn-SOD is a primary antioxidant defense system
+against superoxide radicals, but its product, H(2)O(2), is also deleterious for
+cells. Peroxiredoxin (Prx) enzymes play an important role in eliminating such
+peroxide. Prx1 expression level continuously increased during DC
+differentiation and maturation, whereas Prx6 continuously decreased, and Prx2
+peaked at the immature DC stage. As a consequence, DCs were more resistant than
+monocytes to apoptosis induced by high amounts of oxidized low density
+lipoproteins containing toxic organic peroxides and hydrogen peroxide.
+Furthermore DC-stimulated T cells produced high levels of receptor activator of
+nuclear factor kappaB ligand, a chemotactic and survival factor for monocytes
+and DCs. This study provides insights into the original ability of DCs to
+express very high levels of antioxidant enzymes such as Mn-SOD and Prx1, to
+detoxify oxidized low density lipoproteins, and to induce high levels of
+receptor activator of nuclear factor kappaB ligand by the T cells they activate
+and further emphasizes the role that DCs might play in atherosclerosis, a
+pathology recognized as a chronic inflammatory disorder.",0611082v1
+2008-05-06,Hybrid exchange-correlation functional for accurate prediction of the electronic and structural properties of ferroelectric oxides,"Using a linear combination of atomic orbitals approach, we report a
+systematic comparison of various Density Functional Theory (DFT) and hybrid
+exchange-correlation functionals for the prediction of the electronic and
+structural properties of prototypical ferroelectric oxides. It is found that
+none of the available functionals is able to provide, at the same time,
+accurate electronic and structural properties of the cubic and tetragonal
+phases of BaTiO$_3$ and PbTiO$_3$. Some, although not all, usual DFT
+functionals predict the structure with acceptable accuracy, but always
+underestimate the electronic band gaps. Conversely, common hybrid functionals
+yield an improved description of the band gaps, but overestimate the volume and
+atomic distortions associated to ferroelectricity, giving rise to an
+unacceptably large $c/a$ ratio for the tetragonal phases of both compounds.
+This super-tetragonality is found to be induced mainly by the exchange energy
+corresponding to the Generalized Gradient Approximation (GGA) and, to a lesser
+extent, by the exact exchange term of the hybrid functional. We thus propose an
+alternative functional that mixes exact exchange with the recently proposed GGA
+of Wu and Cohen [Phys. Rev. B 73, 235116 (2006)] which, for solids, improves
+over the treatment of exchange of the most usual GGA's. The new functional
+renders an accurate description of both the structural and electronic
+properties of typical ferroelectric oxides.",0805.0753v1
+2010-03-11,"Tailoring electronic and optical properties of TiO2: nanostructuring, doping and molecular-oxide interactions","Titanium dioxide is one of the most widely investigated oxides. This is due
+to its broad range of applications, from catalysis to photocatalysis to
+photovoltaics. Despite this large interest, many of its bulk properties have
+been sparsely investigated using either experimental techniques or ab initio
+theory. Further, some of TiO2's most important properties, such as its
+electronic band gap, the localized character of excitons, and the localized
+nature of states induced by oxygen vacancies, are still under debate. We
+present a unified description of the properties of rutile and anatase phases,
+obtained from ab initio state of the art methods, ranging from density
+functional theory (DFT) to many body perturbation theory (MBPT) derived
+techniques. In so doing, we show how advanced computational techniques can be
+used to quantitatively describe the structural, electronic, and optical
+properties of TiO2 nanostructures, an area of fundamental importance in applied
+research. Indeed, we address one of the main challenges to TiO2-photocatalysis,
+namely band gap narrowing, by showing how to combine nanostructural changes
+with doping. With this aim we compare TiO2's electronic properties for 0D
+clusters, 1D nanorods, 2D layers, and 3D bulks using different approximations
+within DFT and MBPT calculations. While quantum confinement effects lead to a
+widening of the energy gap, it has been shown that substitutional doping with
+boron or nitrogen gives rise to (meta-)stable structures and the introduction
+of dopant and mid-gap states which effectively reduce the band gap. Finally, we
+report how ab initio methods can be applied to understand the important role of
+TiO2 as electron-acceptor in dye-sensitized solar cells. This task is made more
+difficult by the hybrid organic-oxide structure of the involved systems.",1003.2341v1
+2010-03-23,A mathematical model for breath gas analysis of volatile organic compounds with special emphasis on acetone,"Recommended standardized procedures for determining exhaled lower respiratory
+nitric oxide and nasal nitric oxide have been developed by task forces of the
+European Respiratory Society and the American Thoracic Society. These
+recommendations have paved the way for the measurement of nitric oxide to
+become a diagnostic tool for specific clinical applications. It would be
+desirable to develop similar guidelines for the sampling of other trace gases
+in exhaled breath, especially volatile organic compounds (VOCs) which reflect
+ongoing metabolism. The concentrations of water-soluble, blood-borne substances
+in exhaled breath are influenced by: (i) breathing patterns affecting gas
+exchange in the conducting airways; (ii) the concentrations in the
+tracheo-bronchial lining fluid; (iii) the alveolar and systemic concentrations
+of the compound. The classical Farhi equation takes only the alveolar
+concentrations into account. Real-time measurements of acetone in end-tidal
+breath under an ergometer challenge show characteristics which cannot be
+explained within the Farhi setting. Here we develop a compartment model that
+reliably captures these profiles and is capable of relating breath to the
+systemic concentrations of acetone. By comparison with experimental data it is
+inferred that the major part of variability in breath acetone concentrations
+(e.g., in response to moderate exercise or altered breathing patterns) can be
+attributed to airway gas exchange, with minimal changes of the underlying blood
+and tissue concentrations. Moreover, it is deduced that measured end-tidal
+breath concentrations of acetone determined during resting conditions and free
+breathing will be rather poor indicators for endogenous levels. Particularly,
+the current formulation includes the classical Farhi and the Scheid series
+inhomogeneity model as special limiting cases.",1003.4475v3
+2010-06-22,Automated NanoSIMS Measurements of Spinel Stardust from the Murray Meteorite,"We report new O isotopic data on 41 presolar oxide grains, 38 MgAl2O4
+(spinel) and 3 Al2O3 from the CM2 meteorite Murray, identified with a recently
+developed automated measurement system for the NanoSIMS. We have also obtained
+Mg-Al isotopic results on 29 of the same grains (26 spinel and 3 Al2O3). The
+majority of the grains have O isotopic compositions typical of most presolar
+oxides, fall well into the four previously defined groups, and are most likely
+condensates from either red giant branch or asymptotic giant branch stars. We
+have also discovered several grains with more unusual O and Mg compositions
+suggesting formation in extreme astrophysical environments, such as novae and
+supernovae. One of these grains has massive enrichments in 17O, 25Mg, and 26Mg,
+which are isotopic signatures indicative of condensation from nova ejecta. Two
+grains of supernova origin were also discovered: one has a large 18O/16O ratio
+typical of Group 4 presolar oxides; another grain is substantially enriched in
+16O, and also contains radiogenic 44Ca from the decay of 44Ti, a likely
+condensate from material originating in the O-rich inner zones of a Type II
+supernova. In addition, several Group 2 presolar spinel grains also have large
+25Mg and 26Mg isotopic anomalies that are difficult to explain by standard
+nucleosynthesis in low-mass stars. Auger elemental spectral analyses were
+performed on the grains and qualitatively suggest that presolar spinel may not
+have higher-than- stoichiometric Al/Mg ratios, in contrast to SIMS results
+obtained here and reported previously.",1006.4355v1
+2011-01-25,Extreme 54Cr-rich nano-oxides in the CI chondrite Orgueil -Implication for a late supernova injection into the Solar System,"Systematic variations in 54Cr/52Cr ratios between meteorite classes (Qin et
+al., 2010a; Trinquier et al., 2007) point to large scale spatial and/or
+temporal isotopic heterogeneity in the solar protoplanetary disk. Two
+explanations for these variations have been proposed, with important
+implications for the formation of the Solar System: heterogeneous seeding of
+the disk with dust from a supernova, or energetic-particle irradiation of dust
+in the disk. The key to differentiating between them is identification of the
+carrier(s) of the 54Cr anomalies. Here we report the results of our recent
+NanoSIMS imaging search for the 54Cr-rich carrier in the acid-resistant residue
+of the CI chondrite Orgueil. A total of 10 regions with extreme 54Cr-excesses
+({\delta}54Cr values up to 1500 %) were found. Comparison between SEM, Auger
+and NanoSIMS analyses showed that these 54Cr-rich regions are associated with
+one or more sub-micron (typically less than 200 nm) Cr oxide grains, most
+likely spinels. Because the size of the NanoSIMS primary O- ion beam is larger
+than the typical grain size on the sample mount, the measured anomalies are
+lower limits, and we estimate that the actual 54Cr enrichments in three grains
+are at least 11 times Solar and in one of these may be as high as 50 times
+Solar. Such compositions strongly favor a Type II supernova origin. The
+variability in bulk 54Cr/52Cr between meteorite classes argues for a
+heterogeneous distribution of the 54Cr carrier in the solar protoplanetary disk
+following a late supernova injection event. Such a scenario is also supported
+by the O-isotopic distribution and variable abundances in different planetary
+materials of other presolar oxide and silicate grains from supernovae.",1101.4949v1
+2012-08-27,Ferroelectricity in ultrathin film capacitors,"Going down to the limit of ultrathin films holds promise for a new generation
+of devices such as ferroelectric tunnel junctions or resistive memories.
+However, these length scales also make the devices sensitive to parasitic
+effects related to miniaturization, and a better understanding of what happens
+as size is reduced is of practical importance for the future development of
+these devices.
+  As the experimental advances in materials preparation and characterization
+have come together with great progress in theoretical modeling of
+ferroelectrics, both theorists and experimentalists can finally probe the same
+length and time scales. This allows realtime feedback between theory and
+experiment, with new discoveries now routinely made both in the laboratory and
+on the computer. Throughout this chapter, we will highlight the recent advances
+in density functional theory based modeling and the role it played in our
+understanding of ultrathin ferroelectrics. We will begin with a brief
+introduction to ferroelectricity and ferroelectric oxides, followed by an
+overview of the major theoretical developments. We will then discuss some of
+the subtleties of ferroelectricity in perovskite oxides, before turning our
+attention to the main subject of the chapter -- ferroelectricity in ultrathin
+films. We will discuss in detail the influence of the mechanical, electrical
+and chemical boundary conditions on the stability of the polar state in a
+parallel plate capacitor geometry, introducing the notion of depolarization
+fields that tend to destabilize ferroelectricity. We will look at other ways in
+which a thin ferroelectric can preserve its polar state, focusing on
+ferroelectric domains and domain walls. Finally, we will briefly discuss
+artificially layered ferroelectrics and the potential they hold as tailor-made
+materials for electronic applications.",1208.5309v1
+2014-07-24,Density functional plus dynamical mean field theory of the metal-insulator transition in early transition metal oxides,"The combination of density functional theory and single-site dynamical
+mean-field theory, using both Hartree and full continuous-time quantum Monte
+Carlo impurity solvers, is used to study the metal-insulator phase diagram of
+perovskite transition-metal oxides of the form $AB$O$_3$ with a rare-earth ion
+$A$=Sr, La, Y and transition metal $B$=Ti, V, Cr. The correlated subspace is
+constructed from atomiclike $d$ orbitals defined using maximally localized
+Wannier functions derived from the full $p$-$d$ manifold; for comparison,
+results obtained using a projector method are also given. Paramagnetic DFT+DMFT
+computations using full charge self-consistency along with the standard ""fully
+localized limit"" (FLL) double counting are shown to incorrectly predict that
+LaTiO$_3$, YTiO$_3$, LaVO$_3$ and SrMnO$_3$ are metals. A more general
+examination of the dependence of physical properties on the mean $p$-$d$ energy
+splitting, the occupancy of the correlated $d$ states, the double-counting
+correction, and the lattice structure demonstrates the importance of
+charge-transfer physics even in the early transition-metal oxides and
+elucidates the factors underlying the failure of the standard approximations.
+If the double counting is chosen to produce a $p$-$d$ splitting consistent with
+experimental spectra, single-site dynamical mean-field theory provides a
+reasonable account of the materials properties. The relation of the results to
+those obtained from ""$d$-only"" models in which the correlation problem is based
+on the frontier orbital $p$-$d$ antibonding bands is determined. It is found
+that if an effective interaction $U$ is properly chosen the $d$-only model
+provides a good account of the physics of the $d^1$ and $d^2$ materials.",1407.6505v2
+2014-08-19,Soft chemical control of superconductivity in lithium iron selenide hydroxides Li1-xFex(OH)Fe1-ySe,"Hydrothermal synthesis is described of layered lithium iron selenide
+hydroxides Li1-xFex(OH)Fe1-ySe (x ~ 0.2; 0.02 < y < 0.15) with a wide range of
+iron site vacancy concentrations in the iron selenide layers. This iron vacancy
+concentration is revealed as the only significant compositional variable and as
+the key parameter controlling the crystal structure and the electronic
+properties. Single crystal X-ray diffraction, neutron powder diffraction and
+X-ray absorption spectroscopy measurements are used to demonstrate that
+superconductivity at temperatures as high as 40 K is observed in the
+hydrothermally synthesised samples when the iron vacancy concentration is low
+(y < 0.05) and when the iron oxidation state is reduced slightly below +2,
+while samples with a higher vacancy concentration and a correspondingly higher
+iron oxidation state are not superconducting. The importance of combining a low
+iron oxidation state with a low vacancy concentration in the iron selenide
+layers is emphasised by the demonstration that reductive post-synthetic
+lithiation of the samples turns on superconductivity with critical temperatures
+exceeding 40 K by displacing iron atoms from the Li1-xFex(OH) reservoir layer
+to fill vacancies in the selenide layer",1408.4350v2
+2014-12-01,Training and Operation of an Integrated Neuromorphic Network Based on Metal-Oxide Memristors,"Despite all the progress of semiconductor integrated circuit technology, the
+extreme complexity of the human cerebral cortex makes the hardware
+implementation of neuromorphic networks with a comparable number of devices
+exceptionally challenging. One of the most prospective candidates to provide
+comparable complexity, while operating much faster and with manageable power
+dissipation, are so-called CrossNets based on hybrid CMOS/memristor circuits.
+In these circuits, the usual CMOS stack is augmented with one or several
+crossbar layers, with adjustable two-terminal memristors at each crosspoint.
+Recently, there was a significant progress in improvement of technology of
+fabrication of such memristive crossbars and their integration with CMOS
+circuits, including first demonstrations of their vertical integration.
+Separately, there have been several demonstrations of discrete memristors as
+artificial synapses for neuromorphic networks. Very recently such experiments
+were extended to crossbar arrays of phase-change memristive devices. The
+adjustment of such devices, however, requires an additional transistor at each
+crosspoint, and hence the prospects of their scaling are less impressive than
+those of metal-oxide memristors, whose nonlinear I-V curves enable
+transistor-free operation. Here we report the first experimental implementation
+of a transistor-free metal-oxide memristor crossbar with device variability
+lowered sufficiently to demonstrate a successful operation of a simple
+integrated neural network, a single layer-perceptron. The network could be
+taught in situ using a coarse-grain variety of the delta-rule algorithm to
+perform the perfect classification of 3x3-pixel black/white images into 3
+classes. We believe that this demonstration is an important step towards the
+implementation of much larger and more complex memristive neuromorphic
+networks.",1412.0611v1
+2015-03-30,Electrochemical synthesis of highly ordered nanowires with a rectangular cross-section using an in-plane nanochannel array,"Rapid and reproducible assembly of aligned nanostructures on a wafer-scale is
+a crucial, yet one of the most challenging tasks in the incorporation of
+nanowires into integrated circuits. We present the synthesis of a periodic
+nanochannel template designed for electrochemical growth of perfectly aligned,
+rectangular nanowires over large areas. The nanowires can be electrically
+contacted and characterized in situ using a pre-patterned multi-point
+measurement platform. During the measurement the wires remain within a thick
+oxide matrix providing protection against breaking and oxidation. We use laser
+interference lithography, reactive ion etching and atomic layer deposition to
+create cm-long parallel nanochannels with characteristic dimensions as small as
+40 nm. In a showcase study pulsed electrodeposition of iron is carried out
+creating rectangular shaped iron nanowires within the nanochannels. By design
+of the device, the grown wires are in contact with an integrated electrode
+system on both ends directly after the deposition. No further processing steps
+are required for electrical characterization, minimizing the risk of damage and
+oxidation. The developed nanowire measurement device allows for multi-probe
+resistance measurements and can easily be adopted for transistor applications.
+The guided, in-plane growth of electrodeposited nanowire arrays which are
+tunable in size and density paves the way for the incorporation of nanowires
+into a large variety of multifunctional devices.",1503.08597v1
+2015-06-22,Response of Atmospheric Biomarkers to NOx-induced Photochemistry Generated by Stellar Cosmic Rays for Earth-like Planets in the Habitable Zone of M-Dwarf Stars,"Understanding whether M-dwarf stars may host habitable planets with
+Earth-like atmospheres and biospheres is a major goal in exoplanet research. If
+such planets exist, the question remains as to whether they could be identified
+via spectral signatures of biomarkers. Such planets may be exposed to extreme
+intensities of cosmic rays that could perturb their atmospheric photochemistry.
+Here, we consider stellar activity of M-dwarfs ranging from quiet up to strong
+flaring conditions and investigate one particular effect upon biomarkers,
+namely, the ability of secondary electrons caused by stellar cosmic rays to
+break up atmospheric molecular nitrogen (N2), which leads to production of
+nitrogen oxides in the planetary atmosphere, hence affecting biomarkers such as
+ozone. We apply a stationary model, that is, without a time-dependence, hence
+we are calculating the limiting case where the atmospheric chemistry response
+time of the biomarkers is assumed to be slow and remains constant compared with
+rapid forcing by the impinging stellar flares. This point should be further
+explored in future work with time-dependent models. For the flaring case O3 is
+mainly destroyed via direct titration with nitrogen oxides and not via the
+familiar catalytic cycle photochemistry, which occurs on Earth. For scenarios
+with low O3, Rayleigh scattering by the main atmospheric gases became more
+important for shielding the planetary surface from ultra-violet radiation. A
+major result of this work is that the biomarker O3 survived all the
+stellar-activity scenarios considered except for the strong case, whereas the
+biomarker nitrous oxide could survive in the planetary atmosphere under all
+conditions of stellar activity considered here, which clearly has important
+implications for missions that aim to detect spectroscopic biomarkers.",1506.06508v1
+2015-10-17,Evolution of the dust in V4332 Sagittarii,"An eruptive nova-like event took place in 1994 in the stellar-merger
+candidate V4332 Sgr. Following the eruption, dust consisting of refractory
+silicate rich dust grains containing a significant component of AlO bonding was
+formed sometime between 1998 and 2003. Observations using Spitzer between 2005
+and 2009 show significant changes in the 10 micron silicate stretch feature.
+There is a deepening of the 10 micron silicate stretch as well as the
+development of a feature between about 13 and 20 microns consistent with a
+blend of the MgO and FeO stretching features and the O-Si-O bending mode of
+increasingly ordered silicate dust. Near-infrared observations show the
+presence of AlO and water vapor in the outflow in 2003, 2004 and 2005: the AlO
+has significantly decreased in spectra obtained in 2014 while the water vapor
+remains largely unchanged. An attempt is made to correlate these observations
+and understand the significance of these changes using DUSTY modeling. The
+observations appear consistent with the kinetically-controlled, condensation of
+highly under-oxidized SiO/AlO/Fe/Mg dust grains in the outflow followed by the
+continuous evolution of the initial condensate due to thermal annealing and
+oxidation of the dust via reaction with ambient O, OH and H2O in the expanding,
+cooling shell. Periodic monitoring of this dust shell over the mid-infrared
+spectral range could yield useful information on the evolution of
+under-oxidized silicate condensates exposed to hot water vapor in more
+conventional circumstellar environments.",1510.05074v1
+2016-02-03,Exploiting plume structure to decode gas source distance using metal-oxide gas sensors,"Estimating the distance of a gas source is important in many applications of
+chemical sensing, like e.g. environmental monitoring, or chemically-guided
+robot navigation. If an estimation of the gas concentration at the source is
+available, source proximity can be estimated from the time-averaged gas
+concentration at the sensing site. However, in turbulent environments, where
+fast concentration fluctuations dominate, comparably long measurements are
+required to obtain a reliable estimate. A lesser known feature that can be
+exploited for distance estimation in a turbulent environment lies in the
+relationship between source proximity and the temporal variance of the local
+gas concentration - the farther the source, the more intermittent are gas
+encounters. However, exploiting this feature requires measurement of changes in
+gas concentration on a comparably fast time scale, that have up to now only
+been achieved using photo-ionisation detectors. Here, we demonstrate that by
+appropriate signal processing, off-the-shelf metal-oxide sensors are capable of
+extracting rapidly fluctuating features of gas plumes that strongly correlate
+with source distance. We show that with a straightforward analysis method it is
+possible to decode events of large, consistent changes in the measured signal,
+so-called 'bouts'. The frequency of these bouts predicts the distance of a gas
+source in wind-tunnel experiments with good accuracy. In addition, we found
+that the variance of bout counts indicates cross-wind offset to the centreline
+of the gas plume. Our results offer an alternative approach to estimating gas
+source proximity that is largely independent of gas concentration, using
+off-the-shelf metal-oxide sensors. The analysis method we employ demands very
+few computational resources and is suitable for low-power microcontrollers.",1602.01815v2
+2016-10-04,An observational study of dust nucleation in Mira ($o$ Ceti): II. Titanium oxides are negligible for nucleation at high temperatures,"The formation of silicate dust in oxygen-rich envelopes of evolved stars is
+thought to be initiated by formation of seed particles that can withstand the
+high temperatures close to the stellar photosphere and act as condensation
+cores farther away from the star. Candidate species considered as first
+condensates are TiO and TiO$_2$. We aim to identify and characterize the
+circumstellar gas-phase chemistry of titanium that leads to the formation of
+solid titanium compounds in the envelope of $o$ Cet, the prototypical Mira, and
+seek an observational verification of whether titanium oxides play a major role
+in the onset of dust formation in M-type AGB stars. We present high
+angular-resolution ALMA observations at submillimeter (submm) wavelengths
+supplemented by APEX and Herschel spectra of the rotational features of TiO and
+TiO$_2$. In addition, circumstellar features of TiO and TiI are identified in
+optical spectra which cover multiple pulsation cycles of $o$ Cet. The submm
+ALMA data reveal TiO and TiO$_2$ bearing gas within the extended atmosphere of
+Mira. While TiO is traceable up to a radius (FWHM/2) of 4.0 R$_{\star}$,
+TiO$_2$ extends as far as 5.5 R$_{\star}$ and unlike TiO appears to be
+anisotropically distributed. Optical spectra display variable emission of TiI
+and TiO from inner parts of the extended atmosphere (<3 R$_{\star}$). Chemical
+models which include shocks are in general agreement with the observations of
+gas-phase titanium-bearing molecules. It is unlikely that substantial amounts
+of titanium is locked up in solids because the abundance of the gaseous
+titanium species is very high. In particular, formation of hot titanium-rich
+condensates is very improbable because we find no traces of their hot precursor
+species in the gas phase. It therefore appears unlikely that the formation of
+dust in Mira, and possibly other M-type AGB stars, is initiated by titanium
+oxides.",1610.01141v1
+2016-10-20,First-principles analysis of electron transport in BaSnO$_3$,"BaSnO$_3$ (BSO) is a promising transparent conducting oxide (TCO) with
+reported room-temperature (RT) Hall mobility exceeding 320
+cm$^{2}$V$^{-1}$s$^{-1}$. Among perovskite oxides, it has the highest RT
+mobility, about 30 times higher than that of the prototypical SrTiO$_3$. Using
+first-principles calculations based on hybrid density functional theory, we
+elucidate the physical mechanisms that govern the mobility by studying the
+details of LO-phonon and ionized impurity scattering. A careful numerical
+analysis to obtain converged results within the relaxation-time approximation
+of Boltzmann transport theory is presented. The ${\bf k}$ dependence of the
+relaxation time is fully taken into account. We find that the high RT mobility
+in BSO originates not only from a small effective mass, but also from a
+significant reduction in the phonon scattering rate compared to other
+perovskite oxides; the origins of this reduction are identified. Ionized
+impurity scattering influences the total mobility even at RT for dopant
+densities larger than $5\times10^{18}$ cm$^{-3}$, and becomes comparable to
+LO-phonon scattering for $1\times10^{20}$ cm$^{-3}$ doping, reducing the drift
+mobility from its intrinsic LO-phonon-limited value of $\sim$594
+cm$^{2}$V$^{-1}$s$^{-1}$ to less than 310 cm$^{2}$V$^{-1}$s$^{-1}$. We suggest
+pathways to avoid impurity scattering via modulation doping or polar
+discontinuity doping. We also explicitly calculate the Hall factor and Hall
+mobility, allowing a direct comparison to experimental reports for bulk and
+thin films and providing insights into the nature of the dominant mechanisms
+that limit mobility in state-of-the art samples.",1610.06253v1
+2017-02-25,Electronic conduction properties of indium tin oxide: single-particle and many-body transport,"Indium tin oxide (Sn-doped In$_2$O$_{3-\delta}$ or ITO) is an interesting and
+technologically important transparent conducting oxide. This class of material
+has been extensively studied for decades, with research efforts focusing on the
+application aspects. The fundamental issues of the electronic conduction
+properties of ITO from 300 K down to low temperatures have rarely been
+addressed. Studies of the electrical-transport properties over a wide range of
+temperature are essential to unraveling the underlying electronic dynamics and
+microscopic electronic parameters. We show that one can learn rich physics in
+ITO material, including the semi-classical Boltzmann transport, the
+quantum-interference electron transport, and the electron-electron interaction
+effects in the presence of disorder and granularity. To reveal the
+opportunities that the ITO material provides for fundamental research, we
+demonstrate a variety of charge transport properties in different forms of ITO
+structures, including homogeneous polycrystalline films, homogeneous
+single-crystalline nanowires, and inhomogeneous ultrathin films. We not only
+address new physics phenomena that arise in ITO but also illustrate the
+versatility of the stable ITO material forms for potential applications. We
+emphasize that, microscopically, the rich electronic conduction properties of
+ITO originate from the inherited free-electron-like energy bandstructure and
+low-carrier concentration (as compared with that in typical metals)
+characteristics of this class of material. Furthermore, a low carrier
+concentration leads to slow electron-phonon relaxation, which causes ($i$) a
+small residual resistance ratio, ($ii$) a linear electron diffusion
+thermoelectric power in a wide temperature range 1-300 K, and ($iii$) a weak
+electron dephasing rate. We focus our discussion on the metallic-like ITO
+material.",1702.07845v1
+2018-04-12,Bulk and surface characterization of In$_2$O$_3$(001) single crystals,"A comprehensive bulk and surface investigation of high-quality
+In$_2$O$_3$(001) single crystals is reported. The transparent-yellow,
+cube-shaped single crystals were grown using the flux method. Inductively
+coupled plasma mass spectrometry (ICP-MS) reveals small residues of Pb, Mg, and
+Pt in the crystals. Four-point-probe measurements show a resistivity of 2.0
+$\pm$ 0.5 $\times$ 10$^5$ {\Omega} cm, which translates into a carrier
+concentration of $\approx$10$^{12}$ cm$^{-3}$. The results from x-ray
+diffraction (XRD) measurements revise the lattice constant to 10.1150(5) {\AA}
+from the previously accepted value of 10.117 {\AA}. Scanning tunneling
+microscopy (STM) images of a reduced (sputtered/annealed) and oxidized
+(exposure to atomic oxygen at 300 {\deg}C) surface show a step height of 5
+{\AA}, which indicates a preference for one type of surface termination. The
+surfaces stay flat without any evidence for macroscopic faceting under any of
+these preparation conditions. A combination of low-energy ion scattering (LEIS)
+and atomically resolved STM indicates an indium-terminated surface with small
+islands of 2.5 {\AA} height under reducing conditions, with a surface structure
+corresponding to a strongly distorted indium lattice. Scanning tunneling
+spectroscopy (STS) reveals a pronounced surface state at the Fermi level
+($E_F$). Photoelectron spectroscopy (PES) shows additional, deep-lying band gap
+states, which can be removed by exposure of the surface to atomic oxygen.
+Oxidation also results in a shoulder at the O 1s core level at a higher binding
+energy, possibly indicative of a surface peroxide species. A downward band
+bending of 0.4 eV is observed for the reduced surface, while the band bending
+of the oxidized surface is of the order of 0.1 eV or less.",1804.04478v1
+2018-11-22,Effect of PEG binder on gas sensitivity of ferric oxide films synthesized by spin coating and doctor blade methods,"Ferric oxide (Fe2O3) thin films were fabricated on amorphous nonconductive
+and FTO conductive glass substrates starting from iron acetate nanoparticles by
+the doctor blade and the spin coating techniques. Thin films of Fe2O3 with and
+without the PEG binder were investigated. Films were subsequently annealed at
+500 0C in air for 1 hour to crystallize the phase Fe2O3. The structural and
+chemical properties of Fe2O3 thin films were determined using XRD and FTIR.
+According to XRD, the single phase of Fe2O3 crystallized in the thin film after
+annealing. The optical band gap of synthesized Fe2O3 thin films were determined
+by UV-Visible spectrums. Gas sensitivity, respond time and recovery time of
+Fe2O3 thin films were measured in 1000ppm of CO2 gas using AUTO LAB. Thin films
+synthesized by the doctor blade method were thicker and more uniform than the
+thin films prepared by the spin coating technique. Gas sensitivity of Fe2O3
+films synthesized by the doctor blade method is slightly higher than that of
+the films fabricated by the spin coating technique. Fe2O3 films with the PEG
+binder posses a higher gas sensitivity, lower respond time and lower recovery
+time compared to films without PEG binder. After adding the PEG binder, the
+optical band gap of Fe2O3 thin films reduces. The reduction of the activation
+energy is the reason for the improvement of the gas sensitivity after adding
+the PEG. However, the peak positions of FTIR do not indicate any significant
+change due to the adding of the PEG. Adding the binder increased the gas
+sensitivity of iron oxide by 15.44%. Both FTIR and UV-Visible data confirm the
+formation of Fe2O3 in the thin film.",1811.09614v1
+2020-07-30,"Understanding the Synthetic Pathway to Large Area, High Quality [AgSePh] Nanocrystal Films","Silver benzeneselenolate [AgSePh] is a coordination polymer that hosts a
+hybrid quantum well structure. The recent advancements in the study of its
+tightly bound excitons (~300 meV) and photoconductive properties (recently
+employed in UV photodetection) makes it an interesting representative of a
+material platform that is an environmentally stable alternative to 2D metal
+halide perovskites in terms of optoelectronic properties. To this aim, several
+challenges are to be addressed, among which the lack of control over the
+metal-organic reaction process in the reported synthesis of the [AgSePh]
+nanocrystal film (NC). This issue contributed to cast doubts over the origin of
+its intra-bandgap electronic states. In this article we study all the steps to
+obtain phase pure [AgSePh] NC films, from thin silver films through its
+oxidation and reaction via a chemical vapor-solid with benzeneselenol, by means
+of UV-vis, XRD, SEM, and AFM. Raman and FTIR spectroscopy are also employed to
+provide vibrational peaks assignment, for the first time on this polymer. Our
+analysis supports an acid-base reaction scheme based on an acid attacking the
+metal oxide precursor, generating water as byproduct of the polymeric
+synthesis, speeding up the reaction by solvating the PhSeH. The reaction
+readily goes to completion within 30 min in a supersaturated PhSeH / N2
+atmosphere at 90 {\deg}C. Our analysis suggests the absence of precursor's
+leftovers or oxidized species that could contribute to the intra-gap states. By
+tuning the reaction parameters, we gained control on film morphology to obtain
+substrate-parallel oriented micro-crystals showing different excitonic
+absorption intensities. Finally, centimeters size high quality [AgSePh] NC
+films could be obtained, enabling exploitation of their optoelectronic
+properties, such as UV photodetection, in large-area applications.",2007.15354v2
+2016-11-25,The effect of the thermal reduction on the kinetics of low temperature 4He sorption and the structural characteristics of graphene oxide,"The kinetics of the sorption and the subsequent desorption of 4He by the
+starting graphite oxide (GtO) and the thermally reduced graphene oxide samples
+(TRGO, Treduction = 200, 300, 500, 700 and 900 C) have been investigated in the
+temperature interval 1.5 - 20 K. The effect of the annealing temperature on the
+structural characteristics of the samples was examined by the X-ray diffraction
+(XRD) technique. On lowering the temperature from 20 K to 11-12 K, the time of
+4He sorption increased for all the samples, which is typically observed under
+the condition of thermally activated diffusion. Below 5 K the characteristic
+times of 4He sorption by the GtO and TRGO-200 samples were only weakly
+dependent on temperature, suggesting the dominance of the tunnel mechanism. In
+the same region (T<5 K) the characteristic times of the TRGOs reduced at higher
+temperatures (300, 500, 700 and 900 C) were growing with lowering temperature,
+presumably due to the defects generated in the carbon planes on removing the
+oxygen functional groups (oFGs). The estimates of the activation energy (Ea) of
+4He diffusion show that in the TRGO-200 sample the Ea value is 2.9 times lower
+as compared to the parent GtO, which is accounted for by GtO exfoliation due to
+evaporation of the water intercalated in the interlayer space of carbon. The
+nonmonotonic dependences Ea vs T for the GtO samples treated above 200 C are
+determined by a competition between two processes - the recovery of the
+graphite carbon structure, which increases the activation energy, and the
+generation of defects, which decreases the activation energy by opening
+additional surface areas and ways for sorption. The dependence of the
+activation energy on treatment temperature correlates well with the contents of
+the crystalline phase in GtO varying with a rise of the annealing temperature.",1611.08375v1
+2011-11-14,Nanostructuring of Ba8Ga16Ge30 clathrates,"First thermoelectric properties measurements on bulk nanostructured
+Ba8Ga16Ge30 clathrate-I are presented. A sol-gel-calcination route was
+developed for preparing amorphous nanosized precursor oxides. The further
+reduction of the oxides led to quantitative yield of crystalline nanosized
+Ba8Ga16Ge30 clathrate-I. TEM investigations show the clathrate nanoparticles
+retain the size and morphology of the precursor oxides. The clathrate
+nanoparticles contain mainly thin plates (approx. 300 nm x 300 nm x 50 nm) and
+a small amount of nanospheres (diameter ~ 10 nm). SAED patterns confirm the
+clathrate-I structure type for both morphologies. The powders were compacted
+via Spark Plasma Sintering (SPS) to obtain a bulk nano-structured material. The
+Seebeck coefficient S, measured on low-density samples (53% of {\delta}x-ray),
+reaches -145 {\mu}V/k at 375 {\deg}C. The ZT values are quite low (0.02) due to
+the high resistivity of the sample (two orders of magnitude larger than bulk
+materials) and the low sample density. The trend of the temperature dependence
+of S is in agreement with the values obtained from electronic structure
+calculations and semi-classical Boltzmann transport theory within the constant
+scattering approximation. The total thermal conductivity (1.61 W/mK), measured
+on high density samples (93% of {\delta}x-ray), shows a reduction of 20-25% in
+relation to the bulk materials (2.1 W/mK). A further shaping of the sample for
+the Seebeck coefficient and electrical conductivity measurements was not
+possible due to the presence of cracks. An improvement on the design of the
+pressing tools, loading of the sample and profile of the applied pressure will
+enhance the mechanical stability of the samples. These investigations are now
+in progress.",1111.3233v1
+2013-09-11,Accelerating moderately stiff chemical kinetics in reactive-flow simulations using GPUs,"The chemical kinetics ODEs arising from operator-split reactive-flow
+simulations were solved on GPUs using explicit integration algorithms. Nonstiff
+chemical kinetics of a hydrogen oxidation mechanism (9 species and 38
+irreversible reactions) were computed using the explicit fifth-order
+Runge-Kutta-Cash-Karp method, and the GPU-accelerated version performed faster
+than single- and six-core CPU versions by factors of 126 and 25, respectively,
+for 524,288 ODEs. Moderately stiff kinetics, represented with mechanisms for
+hydrogen/carbon-monoxide (13 species and 54 irreversible reactions) and methane
+(53 species and 634 irreversible reactions) oxidation, were computed using the
+stabilized explicit second-order Runge-Kutta-Chebyshev (RKC) algorithm. The
+GPU-based RKC implementation demonstrated an increase in performance of nearly
+59 and 10 times, for problem sizes consisting of 262,144 ODEs and larger, than
+the single- and six-core CPU-based RKC algorithms using the
+hydrogen/carbon-monoxide mechanism. With the methane mechanism, RKC-GPU
+performed more than 65 and 11 times faster, for problem sizes consisting of
+131,072 ODEs and larger, than the single- and six-core RKC-CPU versions, and up
+to 57 times faster than the six-core CPU-based implicit VODE algorithm on
+65,536 ODEs. In the presence of more severe stiffness, such as ethylene
+oxidation (111 species and 1566 irreversible reactions), RKC-GPU performed more
+than 17 times faster than RKC-CPU on six cores for 32,768 ODEs and larger, and
+at best 4.5 times faster than VODE on six CPU cores for 65,536 ODEs. With a
+larger time step size, RKC-GPU performed at best 2.5 times slower than six-core
+VODE for 8192 ODEs and larger. Therefore, the need for developing new
+strategies for integrating stiff chemistry on GPUs was discussed.",1309.2710v2
+2013-09-12,Persistent photoconductivity in 2-dimensional electron gases at different oxide interfaces,"We report on the transport characterization in dark and under light
+irradiation of three different interfaces: LaAlO3/SrTiO3, LaGaO3/SrTiO3, and
+the novel NdGaO3/SrTiO3 heterostructure. All of them share a perovskite
+structure, an insulating nature of the single building blocks, a polar/non-
+polar character and a critical thickness of four unit cells for the onset of
+conductivity. The interface structure and charge confinement in NdGaO3/SrTiO3
+are probed by atomic-scale- resolved electron energy loss spectroscopy showing
+that, similarly to LaAlO3/SrTiO3, extra electronic charge confined in a sheet
+of about 1.5 nm in thickness is present at the NdGaO3/SrTiO3 interface.
+Electric transport measurements performed in dark and under radiation show
+remarkable similarities and provide evidence that the persistent perturbation
+induced by light is an intrinsic peculiar property of the three investigated
+oxide-based polar/non-polar interfaces. Our work sets a framework for
+understanding the previous contrasting results found in literature about
+photoconductivity in LaAlO3/SrTiO3 and highlights the connection between the
+origin of persistent photoconductivity and the origin of conductivity itself.
+An improved understanding of the photo- induced metastable electron-hole pairs
+might allow to shed a direct light on the complex physics of this system and on
+the recently proposed perspectives of oxide interfaces for solar energy
+conversion.",1309.3120v2
+2017-06-13,Surface Restructuring of Nickel Sulfide Generates Optimally-Coordinated Active Sites for ORR Catalysis,"First-row transition metal oxides and chalcogenides have been found to rival
+the performance of precious metal-based catalysts for the interconversion of
+water and O$_2$. The high lability of the first-row transition metal ions leads
+to surface dynamics under the conditions of catalysis and results in active
+site structures distinct from those expected by surface termination of the bulk
+lattice. While these surface transformations have been well-characterized on
+many metal oxides, the surface dynamics of heavier chalcogenides under
+electrocatalytic conditions are largely unknown. We recently reported that the
+heazlewoodite Ni$_3$S$_2$ bulk phase supports efficient ORR catalysis under
+benign aqueous conditions and exhibits excellent tolerance to electrolyte
+anions such as phosphate which poison Pt. Herein, we combine electrochemistry,
+surface spectroscopy and high resolution microscopy to characterize the surface
+dynamics of Ni$_3$S$_2$ under ORR catalytic conditions. We show that
+Ni$_3$S$_2$ undergoes self-limiting oxidative surface restructuring to form an
+approximately 2 nm amorphous surface film conformally coating the Ni$_3$S$_2$
+crystallites. The surface film has a nominal NiS stoichiometry and is highly
+active for ORR catalysis. Using DFT calculations we show that, to a first
+approximation, the catalytic activity of nickel sulfides is determined by the
+Ni-S coordination numbers at surface exposed sites through a simple geometric
+descriptor. In particular, we find that the surface sites formed dynamically on
+the surface of amorphous NiS during surface restructuring provide an optimal
+energetic landscape for ORR catalysis. This work provides a systematic
+framework for characterizing the rich surface chemistry of metal-chalcogenides
+and provides principles for developing a broader understanding of
+electrocatalysis mediated by amorphous materials.",1706.04090v1
+2017-10-25,NaSn2As2: An Exfoliatable Layered van der Waals Zintl Phase,"The discovery of new families of exfoliatable 2D crystals that have diverse
+sets of electronic, optical, and spin-orbit coupling properties, enables the
+realization of unique physical phenomena in these few-atom thick building
+blocks and in proximity to other materials. Herein, using NaSn2As2 as a model
+system, we demonstrate that layered Zintl phases having the stoichiometry
+ATt2Pn2 (A = Group 1 or 2 element, Tt = Group 14 tetrel element and Pn = Group
+15 pnictogen element) and feature networks separated by van der Waals gaps can
+be readily exfoliated with both mechanical and liquid-phase methods. We
+identified the symmetries of the Raman active modes of the bulk crystals via
+polarized Raman spectroscopy. The bulk and mechanically exfoliated NaSn2As2
+samples are resistant towards oxidation, with only the top surface oxidizing in
+ambient conditions over a couple of days, while the liquid-exfoliated samples
+oxidize much more quickly in ambient conditions. Employing angle-resolved
+photoemission spectroscopy (ARPES), density functional theory (DFT), and
+transport on bulk and exfoliated samples, we show that NaSn2As2 is a highly
+conducting 2D semimetal, with resistivities on the order of 10-6 {\Omega} m.
+Due to peculiarities in the band structure, the dominating p-type carriers at
+low temperature are nearly compensated by the opening of n-type conduction
+channels as temperature increases. This work further expands the family of
+exfoliatable 2D materials to layered van der Waals Zintl phases, opening up
+opportunities in electronics and spintronics.",1710.09059v1
+2017-12-12,"Electronic structure, charge transfer, and intrinsic luminescence of gadolinium oxide nanoparticles: Experiment and theory","The cubic (c) and monoclinic (m) polymorphs of Gd2O3 were studied using the
+combined analysis of several materials science techniques - X-ray diffraction
+(XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy
+(XPS), and photoluminescence (PL) spectroscopy. Density functional theory (DFT)
+based calculations for the samples under study were performed as well. The
+cubic phase of gadolinium oxide (c-Gd2O3) synthesized using a precipitation
+method exhibits spheroidal-like nanoclusters with well-defined edges assembled
+from primary nanoparticles with an average size of 50 nm, whereas the
+monoclinic phase of gadolinium oxide (m-Gd2O3) deposited using explosive
+pyrolysis has a denser structure compared with natural gadolinia. This phase
+also has a structure composed of three-dimensional complex agglomerates without
+clear-edged boundaries that are ~21 nm in size plus a cubic phase admixture of
+only 2 at. % composed of primary edge-boundary nanoparticles ~15 nm in size.
+These atomic features appear in the electronic structure as different defects
+([Gd...O-OH] and [Gd...O-O]) and have dissimilar contributions to the
+charge-transfer processes among the appropriate electronic states with
+ambiguous contributions in the Gd 5p - O 2s core-like levels in the valence
+band structures. The origin of [Gd...O-OH] defects found by XPS was
+well-supported by PL analysis. The electronic and atomic structures of the
+synthesized gadolinias calculated using DFT were compared and discussed on the
+basis of the well-known joint OKT-van der Laan model, and good agreement was
+established.",1712.04115v1
+2018-01-19,Mechanical Properties of Ultralow Density Graphene Oxide/Polydimethylsiloxane Foams,"Low-density, highly porous graphene/graphene oxide (GO) based-foams have
+shown high performance in energy absorption applications, even under high
+compressive deformations. In general, foams are very effective as energy
+dissipative materials and have been widely used in many areas such as
+automotive, aerospace and biomedical industries. In the case of graphene-based
+foams, the good mechanical properties are mainly attributed to the intrinsic
+graphene and/or GO electronic and mechanical properties. Despite the attractive
+physical properties of graphene/GO based-foams, their structural and thermal
+stabilities are still a problem for some applications. For instance, they are
+easily degraded when placed in flowing solutions, either by the collapsing of
+their layers or just by structural disintegration into small pieces. Recently,
+a new and scalable synthetic approach to produce low-density 3D macroscopic GO
+structure interconnected with polydimethylsiloxane (PDMS) polymeric chains
+(pGO) was proposed. A controlled amount of PDMS is infused into the
+freeze-dried foam resulting into a very rigid structure with improved
+mechanical properties, such as tensile plasticity and toughness. The PDMS wets
+the graphene oxide sheets and acts like a glue bonding PDMS and GO sheets. In
+order to obtain further insights on mechanisms behind the enhanced mechanical
+pGO response we carried out fully atomistic molecular dynamics (MD)
+simulations. Based on MD results, we build up a structural model that can
+explain the experimentally observed mechanical behavior.",1801.06257v1
+2018-10-19,Theoretical evidence of spin-orbital-entangled $J_{\mathbf{eff}}$=1/2 state in the 3$d$ transition metal oxide CuAl$_2$O$_4$,"Transition metal oxides exhibit various competing phases and exotic phenomena
+depending on how their reaction to the rich degeneracy of the $d$-orbital.
+Large spin-orbit coupling (SOC) reduces this degeneracy in a unique way by
+providing a spin-orbital-entangled ground state for 4$d$ and 5$d$ transition
+metal compounds. In particular, the spin-orbital-entangled Kramers doublet,
+known as the $J_{\mathbf{eff}}$=1/2 pseudospin, appears in layered iridates and
+$\alpha$-RuCl$_3$, manifesting a relativistic Mott insulating phase. Such
+entanglement, however, seems barely attainable in 3$d$ transition metal oxides,
+where the SOC is small and the orbital angular momentum is easily quenched.
+From experimental and theoretical evidence, here we report on the CuAl$_2$O$_4$
+spinel as the first example of a $J_{\mathbf{eff}}$=1/2 Mott insulator in 3$d$
+transition metal compounds. Based on the experimental study, including
+synthesis of the cubic CuAl$_2$O$_4$ single crystal, density functional theory
+and dynamical mean field theory calculations reveal that the
+$J_{\mathbf{eff}}$=1/2 state survives the competition with an
+orbital-momentum-quenched $S$=1/2 state. The electron-addition spectra probing
+unoccupied states are well described by the $j_{\mathbf{eff}}$=1/2 hole state,
+whereas electron-removal spectra have a rich multiplet structure. The fully
+relativistic entity found in CuAl$_2$O$_4$ provides new insight into the
+untapped regime where the spin-orbital-entangled Kramers pair coexists with
+strong electron correlation.",1810.08594v3
+2019-06-27,On the quest of low temperature nitrogen infusion relevant for superconducting Nb based radio-frequency cavities,"A detailed study of the near-surface structure and composition of Nb, the
+material of choice for Superconducting Radio Frequency accelerator (SRF)
+cavities, is of great importance in order to understand the effects of
+different treatments applied during cavity production. By means of
+surface-sensitive techniques such as grazing incidence diffuse X-ray
+scattering, X-ray reflectivity and X-ray photoelectron spectroscopy,
+single-crystalline Nb(100) samples were investigated in and ex-situ during
+annealing in UHV as well as in nitrogen atmospheres with temperatures and
+pressures similar to the ones employed in real Nb cavity treatments. Annealing
+of Nb specimens up to 800{\deg}C in vacuum promotes partial reduction of the
+natural surface oxides (Nb2O5, NbO2, NbO) into NbO. Upon cooling to 120{\deg}C,
+no evidence of nitrogen-rich layers was detected after nitrogen exposure times
+of up to 48 hours. Oxygen enrichment below the Nb/oxide interface and posterior
+diffusion of oxygen species towards the Nb matrix, along with a partial
+reduction of the natural surface oxides was observed upon a stepwise annealing
+up to 250{\deg}C. Nitrogen introduction to the system at 250{\deg}C neither
+promotes N diffusion into the Nb matrix nor the formation of new surface
+layers. Upon further heating to 500{\deg}C in a nitrogen atmosphere, the growth
+of a new subsurface Nb$_x$N$_y$ layer was detected. These results shed light on
+the composition of the near-surface region of Nb after low-temperature nitrogen
+treatments, which are reported to lead to a performance enhancement of SRF
+cavities.",1906.11530v1
+2019-07-11,"The Composition and Mineralogy of Rocky Exoplanets: A Survey of >4,000 Stars from the Hypatia Catalog","We present a survey of >4,000 star compositions from the Hypatia Catalog to
+examine whether rocky exoplanets (i.e., those with rocky surfaces, dominated by
+silicates) might be geologically similar to Earth, at least with respect to
+composition and mineralogy. To do so, we explore the variety of reported
+stellar compositions to then determine a possible range of exoplanetary mantle
+mineralogies. We find that exoplanetary mantles will likely be dominated by
+olivine and/or orthopyroxene, depending upon Fe partitioning during core
+formation. Some exoplanets may be magnesiowustite- or quartz-saturated, and we
+present a new classification scheme based on the weight $\%$ ratio
+(FeO+MgO)/SiO$_{2}$, to differentiate rock types. But wholly exotic
+mineralogies should be rare to absent. We find that half or more of the range
+of exoplanet mantle mineralogy is controlled by core formation, which we model
+using $\alpha_{Fe}$ = $Fe^{BSP}$/$Fe^{BP}$, where $Fe^{BSP}$ is Fe in a Bulk
+Silicate Planet (bulk planet, minus core), on a cation weight $\%$ basis
+(elemental weight proportions, absent anions) and $Fe^{BP}$ is the cation
+weight $\%$ of Fe for a Bulk Planet. In our solar system, $\alpha_{Fe}$ varies
+from 0 (Mercury) to about 0.54 (Mars). Remaining variations in exoplanet mantle
+mineralogy result from non-trivial variations in star compositions. Our major
+oxide analysis also verifies earlier, isotopic studies indicating that Earth is
+non-solar (non-chondritic). We also find that major oxide estimates for Earth's
+mantle appear to preclude a hidden component in the deep mantle that would
+allow for a bulk solar/chondritic Earth. If it did exist, such a hidden
+component must comprise at least 28% of the mass of the total mantle (to avoid
+negative concentrations of some oxides) and would not look anything like the
+sources of ocean island or mid-ocean ridge basalts.",1907.05506v1
+2019-09-06,Electronic structure of the parent compound of superconducting infinite-layer nickelates,"The search for oxide materials with physical properties similar to the
+cuprate high Tc superconductors, but based on alternative transition metals
+such as nickel, has grown and evolved over time. The recent discovery of
+superconductivity in doped infinite-layer nickelates RNiO2 (R = rare-earth
+element) further strengthens these efforts.With a crystal structure similar to
+the infinite-layer cuprates - transition metal oxide layers separated by a
+rare-earth spacer layer - formal valence counting suggests that these materials
+have monovalent Ni1+ cations with the same 3d electron count as Cu2+ in the
+cuprates. Here, we use x-ray spectroscopy in concert with density functional
+theory to show that the electronic structure of RNiO2 (R = La, Nd), while
+similar to the cuprates, includes significant distinctions. Unlike cuprates
+with insulating spacer layers between the CuO2 planes, the rare-earth spacer
+layer in the infinite-layer nickelate supports a weakly-interacting
+three-dimensional 5d metallic state. This three-dimensional metallic state
+hybridizes with a quasi-two-dimensional, strongly correlated state with 3dx2-y2
+symmetry in the NiO2 layers. Thus, the infinite-layer nickelate can be regarded
+as a sibling of the rare earth intermetallics, well-known for heavy Fermion
+behavior, where the NiO2 correlated layers play an analogous role to the 4f
+states in rare-earth heavy Fermion compounds. This unique Kondo- or
+Anderson-lattice-like ""oxide-intermetallic"" replaces the Mott insulator as the
+reference state from which superconductivity emerges upon doping.",1909.02678v1
+2019-09-06,Hydrogen isotopic evidence for early oxidation of silicate Earth,"The Moon-forming giant impact extensively melts and partially vaporizes the
+silicate Earth and delivers a substantial mass of metal to Earth's core.
+Subsequent evolution of the magma ocean and overlying atmosphere has been
+described by theoretical models but observable constraints on this epoch have
+proved elusive. Here, we report calculations of the primordial atmosphere
+during the magma ocean and water ocean epochs and forge new links with
+observations to gain insight into the behavior of volatiles on the early Earth.
+As Earth's magma ocean crystallizes, it outgasses the bulk of the volatiles
+into the primordial atmosphere. The redox state of the magma ocean controls
+both the chemical composition of the outgassed volatiles and the hydrogen
+isotopic composition of water oceans that remain after hydrogen loss from the
+primordial atmosphere. Whereas water condenses and is retained, molecular
+hydrogen does not condense and can escape, allowing large quantities (~10^2
+bars) of hydrogen - if present - to be lost from Earth in this epoch. Because
+the escaping inventory of H can be comparable to the hydrogen inventory in the
+early oceans, the corresponding deuterium enrichment can be large with a
+magnitude that depends on the initial H2 inventory. By contrast, the common
+view that terrestrial water has a carbonaceous chondrite source requires the
+oceans to preserve the isotopic composition of that source, undergoing minimal
+D-enrichment via H2 loss. Such minimal enrichment places upper limits on the
+amount of primordial H2 in contact with early water oceans (pH2<20 bars),
+implies oxidizing conditions for outgassing from the magma ocean, and suggests
+that Earth's mantle supplied the oxidant for the chemical resorption of metals
+during late accretion.",1909.03001v2
+2019-09-21,Integrating high-quality dielectrics with one-nanometer equivalent oxide thickness on two-dimensional electronic devices,"Two-dimensional (2D) semiconductors are widely recognized as attractive
+channel materials for low-power electronics. However, an unresolved challenge
+is the integration of high-quality, ultrathin high-\k{appa} dielectrics that
+fully meet the roadmap requirements for low-power applications. With a
+dangling-bond free surface, the deposition of dielectrics by atomic layer
+deposition (ALD) on 2D materials is usually characterized with non-uniform
+nucleation and island formation, producing a highly porous dielectric layer
+with serious leakage particularly at the small equivalent oxide thickness (EOT)
+limit. Here, we report the robust ALD of highly uniform high-\k{appa}
+dielectric on 2D semiconductors by using ~0.3 nm-thick exclusively monolayer
+molecular crystal as seeding layer. Ultrathin dielectrics down to 1 nm EOT is
+realized on graphene, MoS2 and WSe2, with considerably reduced roughness,
+density of interface states, leakage current and improved breakdown field
+compared to prior methods. Taking advantage of the reduced EOT, we demonstrate
+graphene RF transistors operating at 60 GHz, as well as MoS2 and WSe2
+complementary metal-oxide-semiconductor (CMOS) transistors with Vdd =0.8 V and
+ideal subthreshold swing (SS) of 60 mV/dec, 20 nm-channel-length MoS2
+transistors with on/off ratio over 10^7. These studies highlight that our
+dielectric integration method is generally applicable for different 2D
+materials, and compatible with top-down fabrication process on large-area
+chemical vapor deposited films.",1909.09753v1
+2020-02-11,Efficient Training of ANN Potentials by Including Atomic Forces via Taylor Expansion and Application to Water and a Transition-Metal Oxide,"Artificial neural network (ANN) potentials enable the efficient large-scale
+atomistic modeling of complex materials with near first-principles accuracy.
+For molecular dynamics simulations, accurate energies and interatomic forces
+are a prerequisite, but training ANN potentials simultaneously on energies and
+forces from electronic structure calculations is computationally demanding.
+Here, we introduce an efficient alternative method for the training of ANN
+potentials on energy and force information based on an extrapolation of the
+total energy via a Taylor expansion. By translating the force information to
+approximate energies, the quadratic scaling with the number of atoms exhibited
+by conventional force-training methods can be avoided, which enables the
+training on reference data sets containing complex atomic structures. We
+demonstrate for different materials systems, clusters of water molecules, bulk
+liquid water, and a lithium transition-metal oxide, that the proposed
+force-training approach provides substantial improvements over schemes that
+train on energies only. Including force information for training reduces the
+size of the reference data sets required for ANN potential construction,
+increases the transferability of the potential, and generally improves the
+force prediction accuracy. For a set of water clusters, the Taylor-expansion
+approach achieves around 50% of the force error improvement compared to the
+explicit training on all force components, at a much smaller computational
+cost. The alternative force training approach thus simplifies the construction
+of general ANN potentials for the prediction of accurate energies and
+interatomic forces for diverse types of materials, as demonstrated here for
+water and a transition-metal oxide.",2002.04172v2
+2020-02-21,Low Thermal Budget High-k/Metal Surface Gate for Buried Donor-Based Devices,"Atomic precision advanced manufacturing (APAM) offers creation of donor
+devices in an atomically thin layer doped beyond the solid solubility limit,
+enabling unique device physics. This presents an opportunity to use APAM as a
+pathfinding platform to investigate digital electronics at the atomic limit.
+Scaling to smaller transistors is increasingly difficult and expensive,
+necessitating the investigation of alternative fabrication paths that extend to
+the atomic scale. APAM donor devices can be created using a scanning tunneling
+microscope (STM). However, these devices are not currently compatible with
+industry standard fabrication processes. There exists a tradeoff between low
+thermal budget (LT) processes to limit dopant diffusion and high thermal budget
+(HT) processes to grow defect-free layers of epitaxial Si and gate oxide. To
+this end, we have developed an LT epitaxial Si cap and LT deposited Al2O3 gate
+oxide integrated with an atomically precise single-electron transistor (SET)
+that we use as an electrometer to characterize the quality of the gate stack.
+The surface-gated SET exhibits the expected Coulomb blockade behavior. However,
+the leverage of the gate over the SET is limited by defects in the layers above
+the SET, including interfaces between the Si and oxide, and structural and
+chemical defects in the Si cap. We propose a more sophisticated gate stack and
+process flow that is predicted to improve performance in future atomic
+precision devices.",2002.09075v2
+2020-04-01,A Computational Model of Levodopa-Induced Toxicity in Substantia Nigra Pars Compacta in Parkinson's Disease,"Parkinson's disease (PD) is caused by the progressive loss of dopaminergic
+cells in substantia nigra pars compacta (SNc). The root cause of this cell loss
+in PD is still not decisively elucidated. A recent line of thinking traces the
+cause of PD neurodegeneration to metabolic deficiency. Due to exceptionally
+high energy demand, SNc neurons exhibit a higher basal metabolic rate and
+higher oxygen consumption rate, which results in oxidative stress. Recently, we
+have suggested that the excitotoxic loss of SNc cells might be due to energy
+deficiency occurring at different levels of neural hierarchy. Levodopa (LDOPA),
+a precursor of dopamine, which is used as a symptom-relieving treatment for PD,
+leads to outcomes that are both positive and negative. Several researchers
+suggested that LDOPA might be harmful to SNc cells due to oxidative stress. The
+role of LDOPA in the course of PD pathogenesis is still debatable. We
+hypothesize that energy deficiency can lead to LDOPA-induced toxicity (LIT) in
+two ways: by promoting dopamine-induced oxidative stress and by exacerbating
+excitotoxicity in SNc. We present a multiscale computational model of
+SNc-striatum system, which will help us in understanding the mechanism behind
+neurodegeneration postulated above and provides insights for developing
+disease-modifying therapeutics. It was observed that SNc terminals are more
+vulnerable to energy deficiency than SNc somas. During LDOPA therapy, it was
+observed that higher LDOPA dosage results in increased loss of somas and
+terminals in SNc. It was also observed that co-administration of LDOPA and
+glutathione (antioxidant) evades LDOPA-induced toxicity in SNc neurons. We show
+that our proposed model was able to capture LDOPA-induced toxicity in SNc,
+caused by energy deficiency.",2004.08320v1
+2017-11-09,Experimental studies of thorium ions implantation from pulse laser plasma into thin silicon oxide layers,"We report the results of experimental studies related to implantation of
+thorium ions into thin silicon dioxide by pulsed plasma fluxes expansion.
+Thorium ions were generated by laser ablation from a metal target, and the
+ionic component of the laser plasma was accelerated in an electric field
+created by the potential difference (5, 10 and 15 kV) between the ablated
+target and SiO2/Si(001) sample. Laser ablation system installed inside the
+vacuum chamber of the electron spectrometer was equipped with YAG:Nd3+ laser
+having the pulse energy of 100 mJ and time duration of 15 ns in the Q-switched
+regime. Depth profile of thorium atoms implanted into the 10 nm thick
+subsurface areas together with their chemical state as well as the band gap of
+the modified silicon oxide at different conditions of implantation processes
+were studied by means of X-ray photoelectron spectroscopy (XPS) and Reflected
+Electron Energy Loss Spectroscopy (REELS) methods. Analysis of chemical
+composition showed that the modified silicon oxide film contains complex
+thorium silicates. Depending on local concentration of thorium atoms, the
+experimentally established band gaps were located in the range of 6.0 - 9.0 eV.
+Theoretical studies of optical properties of the SiO2 and ThO2 crystalline
+systems have been performed by ab initio calculations within hybrid functional.
+Optical properties of the SiO2/ThO2 composite were interpreted on the basis of
+Bruggeman effective medium approximation. A quantitative assessment of the
+yield of isomeric nuclei in ""hot"" laser plasma at the early stages of expansion
+has been performed. The estimates made with experimental results demonstrated
+that the laser implantation of thorium ions into the SiO2 matrix can be useful
+for further research of low-lying isomeric transitions in 229Th isotope with
+energy of 7.8(0.5) eV.",1711.03378v1
+2018-06-26,Updated Compositional Models of the TRAPPIST-1 Planets,"After publication of our initial mass-radius-composition models for the
+TRAPPIST-1 system in Unterborn et al. (2018), the planet masses were updated in
+Grimm et al. (2018). We had originally adopted the data set of Wang et al.,
+2017 who reported different densities than the updated values. The differences
+in observed density change the inferred volatile content of the planets. Grimm
+et al. (2018) report TRAPPIST-1 b, d, f, g, and h as being consistent with <5
+wt% water and TRAPPIST-1 c and e has having largely rocky interiors. Here, we
+present updated results recalculating water fractions and potential alternative
+compositions using the Grimm et al., 2018 masses. Overall, we can only
+reproduce the results of Grimm et al., 2018 of planets b, d and g having small
+water contents if the cores of these planets are small (<23 wt%). We show that,
+if the cores for these planets are roughly Earth-sized (33 wt%), significant
+water fractions up to 40 wt% are possible. We show planets c, e, f, and h can
+have volatile envelopes between 0-35 wt% that are also consistent with being
+totally oxidized and lacking an Fe-core entirely. We note here that a pure
+MgSiO$_3$ planet (Fe/Mg = 0) is not the true lowest density end-member
+mass-radius curve for determining the probability of a planet containing
+volatiles. All planets that are rocky likely contain some Fe, either within the
+core or oxidized in the mantle. We argue the true low density end-member for
+oxidizing systems is instead a planet with the lowest reasonable Fe/Mg and
+completely core-less. Using this logic, we assert that planets b, d and g
+likely must have significant volatile layers because the end-member planet
+models produce masses too high even when uncertainties in both mass and radius
+are taken into account.",1806.10084v1
+2018-07-18,Evolution of Earth-like extrasolar planetary atmospheres: Assessing the atmospheres and biospheres of early Earth analog planets with a coupled atmosphere biogeochemical model,"Understanding the evolution of Earth and potentially habitable Earth-like
+worlds is essential to fathom our origin in the Universe. The search for
+Earth-like planets in the habitable zone and investigation of their atmospheres
+with climate and photochemical models is a central focus in exoplanetary
+science. Taking the evolution of Earth as a reference for Earth-like planets, a
+central scientific goal is to understand what the interactions were between
+atmosphere, geology, and biology on early Earth. The Great Oxidation Event
+(GOE) in Earth's history was certainly caused by their interplay, but the
+origin and controlling processes of this occurrence are not well understood,
+the study of which will require interdisciplinary, coupled models. In this
+work, we present results from our newly developed Coupled Atmosphere
+Biogeochemistry model in which atmospheric O$_2$ concentrations are fixed to
+values inferred by geological evidence. Applying a unique tool, ours is the
+first quantitative analysis of catalytic cycles that governed O$_2$ in early
+Earth's atmosphere near the GOE. Complicated oxidation pathways play a key role
+in destroying O$_2$, whereas in the upper atmosphere, most O$_2$ is formed
+abiotically via CO$_2$ photolysis. The O$_2$ bistability found by Goldblatt et
+al. (2006) is not observed in our calculations likely due to our detailed
+CH$_4$ oxidation scheme. We calculate increased CH$_4$ with increasing O$_2$
+during the GOE. For a given atmospheric surface flux, different atmospheric
+states are possible; however, the net primary productivity (NPP) of the
+biosphere that produces O$_2$ is unique. Mixing, CH$_4$ fluxes, ocean
+solubility, and mantle/crust properties strongly affect NPP and surface O$_2$
+fluxes. Regarding exoplanets, different ""states"" of O$_2$ could exist for
+similar biomass output. Strong geological activity could lead to false
+negatives for life.",1807.06844v1
+2018-08-15,Retrieval of nitric oxide in the mesosphere from SCIAMACHY nominal limb spectra,"We present a retrieval algorithm for nitric oxide (NO) number densities from
+measurements from the SCanning Imaging Absorption spectroMeter for Atmospheric
+CHartographY (SCIAMACHY, on Envisat) nominal limb mode (0--91 km). The NO
+number densities are derived from atmospheric emissions in the gamma bands in
+the range 230--300 nm, measured by the SCIAMACHY ultra-violet (UV) channel 1.
+The retrieval is adapted from the mesosphere and lower thermosphere mode (MLT,
+50--150 km) NO retrieval (Bender et al., 2013, arXiv:1808.02388), including the
+same 3-D ray tracing, 2-D retrieval grid, and regularisations with respect to
+altitude and latitude.
+  Since the nominal mode limb scans extend only to about 91 km, we use NO
+densities in the lower thermosphere (above 92 km), derived from empirical
+models, as a priori input. The priors are the Nitric Oxide Empirical Model
+(NOEM; Marsh et al., 2004) and a regression model derived from the MLT NO data
+comparison (Bender et al., 2015). Our algorithm yields plausible NO number
+densities from 60 to 85 km from the SCIAMACHY nominal limb mode scans. Using a
+priori input substantially reduces the incorrect attribution of NO from the
+lower thermosphere, where no direct limb measurements are available. The
+vertical resolution lies between 5 and 10 km in the altitude range 65--80 km.
+  Analysing all SCIAMACHY nominal limb scans provides almost 10 years (from
+August 2002 to April 2012) of daily NO measurements in this altitude range.
+This provides a unique data record of NO in the upper atmosphere and is
+invaluable for constraining NO in the mesosphere, in particular for testing and
+validating chemistry climate models during this period.",1808.04993v1
+2018-08-20,Anisotropic spin-orbit torque generation in epitaxial SrIrO3 by symmetry design,"Spin-orbit coupling (SOC), the interaction between the electron spin and the
+orbital angular momentum, can unlock rich phenomena at interfaces, in
+particular interconverting spin and charge currents. Conventional heavy metals
+have been extensively explored due to their strong SOC of conduction electrons.
+However, spin-orbit effects in classes of materials such as epitaxial
+5d-electron transition metal complex oxides, which also host strong SOC, remain
+largely unreported. In addition to strong SOC, these complex oxides can also
+provide the additional tuning knob of epitaxy to control the electronic
+structure and the engineering of spin-to-charge conversion by crystalline
+symmetry. Here, we demonstrate room-temperature generation of spin-orbit torque
+on a ferromagnet with extremely high efficiency via the spin-Hall effect in
+epitaxial metastable perovskite SrIrO3. We first predict a large intrinsic
+spin-Hall conductivity in orthorhombic bulk SrIrO3 arising from the Berry
+curvature in the electronic band structure. By manipulating the intricate
+interplay between SOC and crystalline symmetry, we control the spin-Hall torque
+ratio by engineering the tilt of the corner-sharing oxygen octahedra in
+perovskite SrIrO3 through epitaxial strain. This allows the presence of an
+anisotropic spin-Hall effect due to a characteristic structural anisotropy in
+SrIrO3 with orthorhombic symmetry. Our experimental findings demonstrate the
+heteroepitaxial symmetry design approach to engineer spin-orbit effects. We
+therefore anticipate that these epitaxial 5d transition-metal oxide thin films
+can be an ideal building block for low-power spintronics.",1808.06650v1
+2018-12-10,"Graphene oxide membranes: on the absence of ""graphene capillaries"", ""ultrafast flow"" rate and ""ultraprecise sieving""","The data by Q.Yang et al suggest absence of ""ultrafast flow"" of solvent
+across graphene oxide (GO) membranes. The ""ultrafast flow"" is result of using
+unrealistic geometrical model with close packed hole-free micrometer sized GO
+flakes providing only 0.1 % of area in each layer available for permeation. The
+data by Q.Yang et all demonstrate that at least 3-5 % of total layer area are
+available for permeation in real GO membranes due to holes between irregularly
+shaped flakes. At least 2-3 percent of area also needs to be added to the
+permeation cross section due to holes and cracks in GO flakes, especially
+abundant due to prolonged sonication of dispersions. Permeation of solutions
+mostly through pinholes penetrating tens of GO layers suggests that ""graphene
+capillaries"" are not required to explain water flow across the membrane. Taking
+into account realistic packing of GO flakes with holes between the flakes and
+across the flakes, 2-3 orders of magnitude shorter permeation path should be
+formed. Considering shorter zigzag permeation path between GO sheets and 5-10 %
+of area in each layer available for permeation due to holes across and between
+GO flakes, permeation rates across GO membranes can be explained by trivial
+diffusion. In absence of ""graphene capillaries"", the ""ultra-precise sieving""
+related to ""cutoff"" value of 4.5 \AA{} (hydration diameter) provided by
+""graphene capillaries"" has little meaning. As it is well known from earlier
+studies and now demonstrated by Q.Yang et al using their own samples the
+swelling of GO membranes is different for different solutions, depends on
+concentration of solutes and results in delamination in many solutions. Q.Yang
+et al provide controversial data for stability of their GO membranes in water
+citing use of surfactant to prevent dissolving. Oxidation state of GO membranes
+remains to be unknown due to incorrect analysis of XPS spectra.",1812.03941v1
+2019-01-15,"Dust-depletion sequences in damped Ly-α absorbers II. The composition of cosmic dust, from low-metallicity systems to the Galaxy","We aim at assessing what are the most dominant dust species or types,
+including silicate and iron oxide grains present in the ISM, by using recent
+observations of dust depletion of galaxies at various evolutionary stages. We
+use the observed elemental abundances in dust of several metals (O, S, Si, Mg,
+and Fe) in different environments, considering systems with different
+metallicities and dust content, namely damped Lyman-{\alpha} absorbers (DLAs)
+towards quasars and the Galaxy. We derive a possible dust composition by
+computationally finding the statistically expected elemental abundances in dust
+assuming a set of key dust species with the iron content as a free parameter.
+Carbonaceous dust is not considered in the present study. Metallic iron (likely
+in the form of inclusions in silicate grains) and iron oxides is an important
+component of the mass composition of carbon-free dust. Iron oxides make up a
+significant mass fraction (~1/4 in some cases) of the oxygen-bearing dust and
+there are good reasons to believe that metallic iron constitutes a similar mass
+fraction of dust. W\""ustite (FeO) could be a simple explanation for the
+depletion of iron and oxygen because it is easily formed. There appears to be
+no silicate species clearly dominating the silicate mass, but rather a mix of
+iron-poor as well as iron-rich olivine and pyroxene. To what extent sulphur
+depletion is due to sulfides remains unclear. In general, there seems to be
+little evolution of the dust composition (not considering carbonaceous dust)
+from low-metallicity systems to the Galaxy.",1901.04710v3
+2019-02-05,Reduction and simultaneous doping of graphene oxide to repel LDL in treatment of atherosclerosis disease,"Atherosclerotic disease develops when there is endothelial dysfunction,
+making low density lipoproteins (LDL) which are cholesterol carriers traveling
+in the blood, very likely to penetrate the endothelium layer triggering the
+formation of the atheromatous plaque and leading to the obstruction of blood
+vessels. For some time now, devices called stents have been used to re-open the
+light of the plugged artery, allowing the restoration of blood flow. However,
+this treatment has disadvantages like developing intra-stent restenosis and
+progression of the atherosclerosis, clogging the blood vessel again. For these
+reasons it is necessary to develop new materials and strategies focused on the
+prevention and correction of this pathology and its subsequent complications.
+In the present work, a reduction and in situ nitrogen doping method in graphene
+oxide (N-rGO) was studied. By means of XPS a 9.57% at of nitrogen doping was
+demonstrated and was found that the pyrrole type nitrogen is predominant. Due
+to nitrogen doping and pyrrolic sites, the N-rGO surface reached high levels of
+negative electric charge, which was verified by Electrostatic Force Microscopy
+(EFM) and wettability tests between the LDL at different oxidation levels and
+the synthesized N-rGO; contact angles between 95.7{\deg} and 130.4{\deg} were
+obtained which indicates repulsion between both materials. The N-rGO was also
+characterized by SEM and TEM where a wrinkled morphology typical of this type
+of material was observed and the hexagonal atomic arrangement of GO is
+distinguished. Finally, cell viability tests using
+3-(4,5-dimethylthiazolyl)-2,5-diphenyltetrazolium bromide (MTT) assay were
+carried out on human umbilical cord endothelial cells (HUVEC) to analyze the
+cellular response at different concentrations of N-rGO, obtaining favorable
+behavior up to concentrations of 100 ({\mu}g/mL).",1902.01850v1
+2019-03-03,Topological phases in pyrochlore thallium niobate Tl$_2$Nb$_2$O$_{6+x}$,"The discovery of new topological electronic materials brings a chance to
+uncover novel physics and plays a key role in observing and controlling various
+intriguing phenomena. Up to now, many materials have been theoretically
+proposed and experimentally proved to host different kinds of topological
+states. Unfortunately, there is little convincing experimental evidence for the
+existence of topological oxides. The reason is that oxidation of oxygen leads
+to ionic crystal in general and makes band inversion unlikely. In addition, the
+realization of different topological states in a single material is quite
+difficult, but strongly needed for exploring topological phase transitions. In
+this work, using first-principles calculations and symmetry analysis, we
+propose that the experimentally tunable continuous solid solution of oxygen in
+pyrochlore Tl$_2$Nb$_2$O$_{6+x}$ ($ 0\leq x \leq 1.0$) leads to various
+topological states. Topological insulator, Dirac semimetal and triply
+degenerate nodal point semimetal can be realized in it via changing the oxygen
+content and/or tuning the crystalline symmetries. When $x = 1$, it is a
+semimetal with quadratic band touching point at Fermi level. It transits into a
+Dirac semimetal or a topological insulator depending on the in-plane strain.
+When $x = 0.5$, the inversion symmetry is spontaneously broken in
+Tl$_2$Nb$_2$O$_{6.5}$, leading to triply degenerate nodal points. When $x = 0$,
+Tl$_2$Nb$_2$O$_6$ becomes a trivial insulator with a narrow band gap. These
+topological phase transitions driven by solid solution of oxygen are unique and
+physically plausible due to the variation of valence state of $Tl^{1+}$ and
+$Tl^{3+}$. This topological oxide will be promising for studying correlation
+induced topological states and potential applications.",1903.00891v4
+2019-03-14,Observation of a Correlation Between Internal friction and Urbach Energy in Amorphous Oxides Thin Films,"We have investigated by spectroscopic ellipsometry (SE, 190-1700 nm) the
+optical properties of uniform, amorphous thin films of Ta2O5 and Nb2O5 as
+deposited and after annealing, and after so-called ""doping"" with Ti atoms which
+leads to mixed oxides. Ta2O5 and Ti:Ta2O5 are currently used as high-index
+components in Bragg reflectors for Gravitational Wave Detectors. Parallel to
+the optical investigation, we measured the mechanical energy dissipation of the
+same coatings, through the so-called ""loss angle"" phi = Q^-1, which quantifies
+the energy loss in materials. By applying the well-known Cody-Lorentz model in
+the analysis of SE data we have been able to derive accurate information on the
+fundamental absorption edge through important parameters related to the
+electronic density of states, such as the optical gap (E_g) and the energy
+width of the exponential Urbach tail (the Urbach energy E_U). We have found
+that E_U is neatly reduced by suitable annealing as is also perceptible from
+direct inspection of SE data. Ti-doping also points to a minor decrease of E_U.
+The reduction of E_U parallels a lowering of the mechanical losses quantified
+by the loss angle phi. The correlation highlights that both the electronic
+states responsible of Urbach tail and the internal friction are sensitive to a
+self-correlation of defects on a medium-range scale, which is promoted by
+annealing and in our case, to a lesser extent, by doping. These observations
+may contribute to a better understanding of the relationship between structural
+and mechanical properties in amorphous oxides.",1903.06094v5
+2019-11-01,Which oxidation state of uranium and thorium as point defects in xenotime is favorable?,"Relativistic study of xenotime, YPO$_4$, containing atoms thorium and uranium
+as point defects is performed in the framework of cluster model with using the
+compound-tunable embedding potential (CTEP) method proposed by us recently. The
+Y-(PO$_4$)$_6$-Y'$_{22}$-O'$_{104}$ cluster for xenotime is considered, in
+which central part, [Y-(PO$_4$)$_6$]$^{-15}$, is the main cluster, whereas
+outermost 22 atoms of yttrium and 104 atoms of oxygen are treated as its
+environment and compose electron-free CTEP with the total charge of $+15$. The
+P and O atoms of the orthophosphate groups nearest to the central Y atom are
+treated at all-electron level. The central Y, its substitutes, Th and U,
+together with environmental Y atoms are described within different versions of
+the generalized relativistic pseudopotential method. Correctness of our cluster
+and CTEP models, constructed in the paper, is justified by comparing the Y-O
+and P-O bond lengths with corresponding periodic structure values of the \ypo4
+crystal, both experimental and theoretical. Using this cluster model, chemical
+properties of solitary point defects, X = U, Th, in xenotime are analyzed. It
+has been shown that the oxidation state ${+3}$ is energetically more profitable
+than ${+4}$ not only for thorium but for uranium as well ($\Delta E \approx 5$
+eV) despite the notably higher ionic radius of U$^{+3}$ compared to Y$^{+3}$,
+whereas ionic radii of U$^{+4}$ and Y$^{+3}$ are close. This leads to notable
+local deformation of crystal geometry around the U$^{+3}$ impurity in xenotime
+and contradicts to widespread opinion about favorite oxidation state of uranium
+in such kind of minerals.",1911.00365v3
+2020-06-16,Electromagnetic Duality and D3-Brane Scattering Amplitudes Beyond Leading Order,"We use on-shell methods to study the non-supersymmetric and supersymmetric
+low-energy S-matrix on a probe D3-brane, including both the 1-loop
+contributions of massless states as well as the effects of higher-derivative
+operators. Our results include: (1) A derivation of the duality invariance of
+Born-Infeld electrodynamics as the dimensional oxidation of the group of
+spatial rotations transverse to a probe M2-brane; this is done using a novel
+implementation of subtracted on-shell recursion. (2) The first explicit
+loop-level BCJ double-copy in a non-gravitational model, namely the calculation
+of the 4-point self-dual amplitude of non-supersymmetric Born-Infeld. (3) From
+previous results for $n$-point self-dual 1-loop BI amplitudes and the
+conjectured dimension-shifting relations in Yang-Mills, we obtain an explicit
+all-multiplicity, at all orders in $\epsilon$, expression for the 1-loop
+integrand of the MHV sector of $\mathcal{N}=4$ DBI. (4) For all $n>4$, the
+explicitly integrated duality-violating 1-loop amplitudes (self-dual and
+next-to-self-dual in pure BI as well as MHV in $\mathcal{N}=4$ DBI) are shown
+to be removable at $\mathcal{O}(\epsilon^0)$ by adding finite local
+counterterms; we propose that this may be true more generally at 1-loop order.
+(5) We find that in non-supersymmetric Born-Infeld, not all finite local
+counterterms needed to restore electromagnetic duality can be constructed using
+the double-copy with higher-derivative corrections, suggesting a fundamental
+tension between electromagnetic duality and color-kinematics duality at
+loop-level. Finally we comment on oxidation of duality symmetries in
+supergravity and the parallels it has to the M2-brane to D3-brane oxidation
+demonstrated in this paper.",2006.08928v3
+2020-08-19,Role of Catalyst Support and Regioselectivity of Molecular Adsorption on a Metal Oxide Surface: NO Reduction on Cu/γ-alumina,"The role of catalyst support and regioselectivity of molecular adsorption on
+a metal oxide surface is investigated for the NO reduction on a
+Cu/{\gamma}-alumina heterogeneous catalyst. For the solid surface,
+computational models of the {\gamma}-alumina surface are constructed based on
+the Step-by-Step Hydrogen Termination (SSHT) approach. Dangling bonds, which
+appear by cutting the crystal structure of a model, are terminated stepwise
+with H atoms until the model has an appropriate energy gap. The obtained SSHT
+models exhibit the realistic infrared (IR) and ultraviolet-visible (UV/Vis)
+spectra. Vibronic coupling density (VCD), as a reactivity index, is employed to
+elucidate the regioselectivity of the Cu adsorption on the {\gamma}-alumina and
+that of the NO adsorption on the Cu/{\gamma}-alumina in place of the frontier
+orbital theory that could not provide clear results. We discovered that the
+highly dispersed Cu atoms are loaded on Lewis-basic O atoms, which is known as
+anchoring effect, located in the tetrahedral sites of the {\gamma}-alumina
+surface. The role of the {\gamma}-alumina support is to raise the frontier
+orbital of the Cu catalyst, which in turn gives rise to the electron
+back-donation from the Cu/{\gamma}-alumina to NO. In addition, the penetration
+of the VCD distribution of the Cu/{\gamma}-alumina into the {\gamma}-alumina
+support indicates that the excessive reaction energies dissipate into the
+support after the NO adsorption and reduction. In other words, the support
+plays the role of a heat bath. The NO reduction on the Cu/{\gamma}-alumina
+proceeds even in an oxidative atmosphere because the Cu-NO bond is strongly
+bounded compared to the Cu-O2 bond.",2008.08329v1
+2020-09-07,Giant Polarization and Abnormal Flexural Deformation in Bent Freestanding Perovskite Oxides,"Recent realizations of ultrathin freestanding perovskite oxides offer a
+unique platform to probe novel properties in two-dimensional oxides. Here, we
+observed a giant flexoelectric response in freestanding BiFeO3 and SrTiO3 in
+their bent state arising from strain gradients up to 4x10e7/m, suggesting a
+promising approach for realizing extremely large polarizations. Additionally, a
+substantial reversible change in thickness was discovered in bent freestanding
+BiFeO3, which implies an unusual bending-expansion/shrinkage and
+thickness-dependence Poisson's ratios in this ferroelectric membrane that has
+never been seen before in crystalline materials. Our theoretical modeling
+reveals that this unprecedented flexural deformation within the membrane is
+attributable to a flexoelectricity-piezoelectricity interplay. The finding
+unveils intriguing nanoscale electromechanical properties and provides guidance
+for their practical applications in flexible nanoelectromechanical systems.",2009.03177v1
+2020-09-30,Effect of mantle oxidation state and escape upon the evolution of Earth's magma ocean atmosphere,"The magma ocean period was a critical phase determining how Earth atmosphere
+developed into habitability. However there are major uncertainties in the role
+of key processes such as outgassing from the planetary interior and escape of
+species to space that play a major role in determining the atmosphere of early
+Earth. We investigate the influence of outgassing of various species and escape
+of H$_2$ for different mantle redox states upon the composition and evolution
+of the atmosphere for the magma ocean period. We include an important new
+atmosphere-interior coupling mechanism namely the redox evolution of the mantle
+which strongly affects the outgassing of species. We simulate the volatile
+outgassing and chemical speciation at the surface for various redox states of
+the mantle by employing a C-H-O based chemical speciation model combined with
+an interior outgassing model. We then apply a line-by-line radiative transfer
+model to study the remote appearance of the planet in terms of the infrared
+emission and transmission. Finally, we use a parameterized diffusion-limited
+and XUV energy-driven atmospheric escape model to calculate the loss of H$_2$
+to space. We have simulated the thermal emission and transmission spectra for
+reduced or oxidized atmospheres present during the magma ocean period of Earth.
+Reduced or thin atmospheres consisting of H$_2$ in abundance emit more
+radiation to space and have larger effective height as compared to oxidized or
+thick atmospheres which are abundant in H$_2$O and CO$_2$. We obtain the
+outgassing rates of H2 from the mantle into the atmosphere to be a factor of
+ten times larger than the rates of diffusion-limited escape to space. Our work
+presents useful insight into the development of Earth atmosphere during the
+magma ocean period as well as input to guide future studies discussing
+exoplanetary interior compositions.",2009.14599v2
+2020-10-08,Prediction of crystallized phases of amorphous Ta$_2$O$_5$-based mixed oxide thin films using density functional theory calculations,"The genomics approach to materials, heralded by increasingly accurate density
+functional theory (DFT) calculations conducted on thousands of crystalline
+compounds, has led to accelerated material discovery and property predictions.
+However, so far amorphous materials have been largely excluded from this as
+these systems are notoriously difficult to simulate. Here we study amorphous
+Ta$_2$O$_5$ thin films mixed with Al$_2$O$_3$, SiO$_2$, Sc$_2$O$_3$, TiO$_2$,
+ZnO, ZrO$_2$, Nb$_2$O$_5$ and HfO$_2$ to identify their crystalline structure
+upon post-deposition annealing in air both experimentally and with simulations.
+Using the Materials Project open database, phase diagrams based on DFT
+calculations are constructed for the mixed oxide systems and the annealing
+process is evaluated via grand potential diagrams with varying oxygen chemical
+potential. Despite employing calculations based on crystalline bulk materials,
+the predictions agree well with the experimentally observed crystallized phases
+of the amorphous films. Only in two cases the database leads to incorrect
+predictions: in TiO$_2$-doped Ta$_2$O$_5$ because it does not contain a ternary
+compound found experimentally, and in Sc$_2$O$_3$-doped Ta$_2$O$_5$ because DFT
+overestimates the formation enthalpy difference between Sc$_2$O$_3$ and
+Ta$_2$O$_5$ and thus does not reproduce observed oxygen competition effects. In
+the absence of ternary phases, the dopant acts as an amorphizer agent
+increasing the thermal stability of Ta$_2$O$_5$. These results show that DFT
+calculations can be applied for the prediction of crystallized structures of
+annealed amorphous materials. This could pave the way for accelerated
+\textit{in silico} material discovery and property predictions using the
+powerful genomic approach for amorphous oxide coatings employed in a wide range
+of applications such as optical coatings, energy storage and electronic
+devices.",2010.04036v1
+2020-10-27,Predicting Gas-Particle Partitioning Coefficients of Atmospheric Molecules with Machine Learning,"The formation, properties and lifetime of secondary organic aerosols in the
+atmosphere are largely determined by gas-particle partitioning coefficients of
+the participating organic vapours. Since these coefficients are often difficult
+to measure or compute, we developed a machine learning (ML) model to predict
+them given molecular structure as input. Our data-driven approach is based on
+the dataset by Wang et al. (Atmos. Chem. Phys., 17, 7529 (2017)), who computed
+the partitioning coefficients and saturation vapour pressures of 3414
+atmospheric oxidation products from the master chemical mechanism using the
+COSMOtherm program. We train a kernel ridge regression (KRR) ML model on the
+saturation vapour pressure ($P_{sat}$), and on two equilibrium partitioning
+coefficients: between a water-insoluble organic matter phase and the gas phase
+($K_{WIOM/G}$), and between an infinitely dilute solution with pure water and
+the gas phase ($K_{W/G}$). For the input representation of the atomic structure
+of each organic molecule to the machine, we test different descriptors. Our
+best ML model predicts $P_{sat}$ and $K_{WIOM/G}$ to within 0.3 and $K_{W/G}$
+to within 0.4 logarithmic units of the original COSMOtherm calculations. This
+is equal or better than the typical accuracy of COSMOtherm predictions compared
+to experimental data. We then apply our ML model to a dataset of 35,383
+molecules that we generated based on a carbon 10 backbone and functionalized
+with 0 to 6 carboxyl, carbonyl or hydroxyl groups to evaluate its performance
+for polyfunctional compounds with potentially low $P_{sat}$. The resulting
+$P_{sat}$ and partitioning coefficient distributions were physico-chemically
+reasonable, and the volatility predictions for the most highly oxidized
+compounds were in qualitative agreement with experimentally inferred
+volatilities of atmospheric oxidation products with similar elemental
+composition.",2010.14207v1
+2021-03-25,Synthesis of metallic nanoparticles for heterogeneous catalysis: Application to the Direct Borohydride Fuel Cell,"Until now, the fabrication of electrocatalysts to guarantee long life of fuel
+cells and low consumption of noble metals remains a major challenge. The
+electrocatalysts based on metals or metal oxides which are used today are
+limited by the complexity of their synthesis processes and require several
+steps before depositing the catalysts on the substrate. Herein is described a
+chemical synthesis process that consists of a single-step synthesis and direct
+deposition of catalysts nanoparticles such as gold (Au), palladium (Pd) and
+platinum (Pt) in the thickness of a carbon-fibers-based porous transport layer
+(PTL). The synthesis process essentially consists of dissolving in the same
+PGMEA (Propylene glycol methyl ether acetate) solvent a metal precursor (HAuCl4
+or PdNO2 or PtCl4) and a homopolymer PMMA (Polymethylmetacrylate), then the
+metal solution is deposited on the surface of the PTL after cleaning. Special
+emphasis is made on Pt-based materials. The obtained PTL-supported
+nanoparticles were firstly characterized by scanning electron microscopy (SEM)
+to evaluate their morphology, and then X-Ray diffraction (XRD) to observe the
+crystal phases. To validate the methodology, Pt-coated PTL materials have been
+used as anode for the borohydride oxidation reaction (BOR) in a direct
+borohydride fuel cell (DBFC) and compared to a state-of-the-art nickel
+electrode. There is an optimum loading of platinum (below 0.16 mg Pt/cm2) which
+constitutes the best compromise between power density and faradic efficiency
+for the borohydride oxidation reaction (BOR). Thanks to this low Pt loading,
+hydrogen evolved during the anodic reaction is completely valorized. These
+electrodes combine the advantages of high-performance with a very low metal
+loading, hence lowering materials cost.",2103.13640v1
+2021-05-18,"Effect of In-vitro Heat Stress Challenge on the function of Blood Mononuclear Cells from Dairy Cattle ranked as High, Average and Low Immune Responders","The warming climate is causing livestock to experience heat stress at an
+increasing frequency. Holstein cows are particularly susceptible to heat stress
+because of their high metabolic rate. Heat stress negatively affects immune
+function, particularly with respect to the cell-mediated immune response, which
+leads to increased susceptibility to disease. Cattle identified as having
+enhanced immune response have lower incidence of disease. Therefore, the
+objective of this study was to evaluate the impact of in vitro heat challenge
+on blood mononuclear cells from dairy cattle, that had previously been ranked
+for immune response, in terms of heat shock protein 70 concentration, nitric
+oxide production, and cell proliferation. Bovine blood mononuclear cells, from
+Holstein dairy cattle previously ranked for immune response based on their
+estimated breeding values, were subjected to three heat treatments:
+thermoneutral, heat stress 1 and heat stress 2. Cells of each treatment were
+evaluated for heat shock protein 70, cell proliferation and nitric oxide
+production. Blood mononuclear cells from dairy cattle classified as high immune
+responders, based on their estimated breeding values for antibody and
+cell-mediated responses, produced a significantly greater concentration of heat
+shock protein 70 under most heat stress treatments compared to average and low
+responders, and greater cell-proliferation across all treatments. Similarly, a
+trend was observed where high responders displayed greater nitric oxide
+production compared to average and low responders across heat treatments.
+Overall, these results suggest that blood mononuclear cells from high immune
+responder dairy cows are more thermotolerant compared to average and low immune
+responders",2105.08801v1
+2021-06-21,Enhancing the third-order optical nonlinear performance in CMOS devices with integrated 2D graphene oxide films,"We report enhanced nonlinear optics in complementary metal oxide
+semiconductor compatible photonic platforms through the use of layered two
+dimensional (2D) graphene oxide (GO) films. We integrate GO films with silicon
+on insulator nanowires (SOI), high index doped silica glass (Hydex) and silicon
+nitride (SiN) waveguides and ring resonators, to demonstrate an enhanced
+optical nonlinearity including Kerr nonlinearity and four wave mixing (FWM).
+The GO films are integrated using a large area, transfer free, layer by layer
+method while the film placement and size are controlled by photolithography. In
+SOI nanowires we observe a dramatic enhancement in both the Kerr nonlinearity
+and nonlinear figure of merit (FOM) due to the highly nonlinear GO films. Self
+phase modulation (SPM) measurements show significant spectral broadening
+enhancement for SOI nanowires coated with patterned films of GO. The dependence
+of GO Kerr nonlinearity on layer number and pulse energy shows trends of the
+layered GO films from 2D to quasi bulk like behavior. The nonlinear parameter
+of GO coated SOI nanowires is increased 16 fold, with the nonlinear FOM
+increasing over 20 times to a FOM greater than 5. We also observe an improved
+FWM efficiency in SiN waveguides integrated with 2D layered GO films. FWM
+measurements for samples with different numbers of GO layers and at different
+pump powers are performed, achieving up to 7.3 dB conversion efficiency (CE)
+enhancement for a uniformly coated device with 1 layer of GO and 9.1 dB for a
+patterned device with 5 layers of GO. These results reveal the strong potential
+of GO films to improve the nonlinear optics of silicon, Hydex and SiN photonic
+devices.",2106.10779v1
+2021-10-15,Retention of water in terrestrial magma oceans and carbon-rich early atmospheres,"Massive steam and CO$_2$ atmospheres have been proposed for magma ocean
+outgassing of Earth and terrestrial planets. Yet formation of such atmospheres
+depends on volatile exchange with the molten interior, governed by volatile
+solubilities and redox reactions. We determine the evolution of magma
+ocean--atmosphere systems for a range of oxygen fugacities, C/H ratios and
+hydrogen budgets that include redox reactions for hydrogen (H$_2$--H$_2$O),
+carbon (CO--CO$_2$), methane (CH$_4$), and solubility laws for H$_2$O and
+CO$_2$. We find that small initial budgets of hydrogen, high C/H ratios, and
+oxidizing conditions, suppress outgassing of hydrogen until the late stage of
+magma ocean crystallization. Hence early atmospheres in equilibrium with magma
+oceans are dominantly carbon-rich, and specifically CO-rich except at the most
+oxidizing conditions. The high solubility of H$_2$O limits its outgassing to
+melt fractions below $\sim$30\%, the fraction at which the mantle transitions
+from vigorous to sluggish convection with melt percolation. Sluggish melt
+percolation could enable a surface lid to form, trapping water in the interior
+and thereby maintaining a carbon-rich atmosphere (equilibrium crystallization).
+Alternatively, efficient crystal settling could maintain a molten surface,
+promoting a transition to a water-rich atmosphere (fractional crystallization).
+However, additional processes, including melt trapping and H dissolution in
+crystallizing minerals, further conspire to limit the extent of H outgassing,
+even for fractional crystallization. Hence, much of the water delivered to
+planets during their accretion can be safely harbored in their interiors during
+the magma ocean stage, particularly at oxidizing conditions.",2110.08029v2
+2021-11-01,A New Class of Alumina-Forming Superalloy for 3D Printing,"A new class of crack-resistant nickel-based superalloy containing high
+$\gamma^\prime$ fraction is studied for the laser-powder bed fusion (L-PBF)
+process. The effects of the (Nb+Ta)/Al ratio is emphasised, a strategy that is
+shown to confer excellent low-temperature strength whilst maintaining oxidation
+resistance at high temperatures via stable alumina scale formation. The
+processability of the new alloys is characterised with respect to defect
+assessment by micro-focus x-ray computed tomography; use is made of a prototype
+turbine blade geometry and the heritage alloy CM247LC as a benchmark. In all
+cases, some processing-related porosity is present in thin wall sections such
+as the trailing edge, but this can be avoided by judicious processing. The
+cracking seen in CM247LC -- in solid-state, liquation and solidification forms
+-- is avoided. A novel sub-solvus heat treatment strategy is proposed which
+takes advantage of AM not requiring solutioning; super-solvus heat treatment is
+inappropriate since it embrittles the material by deterioration of the texture
+and coarsening of grain boundary carbides. The tensile strength of the new
+superalloy is greatest when the Nb+Ta content is highest and exceeds that of
+CM247LC up to $\sim$900$\,$$^\circ$C. The oxidation resistance is best when Al
+content is highest, and oxidation-assisted cracking resistance maximized when
+the (Nb+Ta)/Al ratio is balanced. In all cases these are equivalent or superior
+to that of CM247LC. Nevertheless, the creep resistance of the new alloys is
+somewhat inferior to that of CM247LC for which the $\gamma^\prime$, C, and B
+contents are higher; this implies a processing/property trade-off which
+requires further clarification.",2111.01049v1
+2021-11-16,Hydrogen incorporation into amorphous indium gallium zinc oxide thin-film transistors,"Within the subgap of amorphous oxide semiconductors like amorphous indium
+gallium zinc oxide (a-IGZO) are donor-like and acceptor-like states that
+control the operational physics of optically transparent thin-film transistors
+(TFTs). Hydrogen incorporation into the channel layer of a top-gate a-IGZO TFT
+exists as an electron donor that causes an observed negative shift in the drain
+current-gate voltage ($\mathrm{I_{D} - V_{G}}$) transfer curve turn-on voltage.
+Normally, hydrogen is thought to create shallow electronic states just below
+the conduction band mobility edge, with the donor ionization state controlled
+by equilibrium thermodynamics involving the position of the Fermi level with
+respect to the donor ionization energy. However, hydrogen does not behave as a
+normal donor as revealed by the subgap density of states (DoS) measured by the
+photoconduction response of top-gate a-IGZO TFTs to within 0.3 eV of the CBM
+edge. Specifically, the DoS shows a subgap peak above the valence band mobility
+edge growing at the same rate that $\mathrm{I_{D} - V_{G}}$ transfer curve
+measurements suggest that hydrogen was incorporated into the channel layer.
+Such hydrogen donor behavior in a-IGZO is anomalous and can be understood as
+follows: Non-bonded hydrogen ionization precedes its incorporation into the
+a-IGZO network as a bonded species. Ionized hydrogen bonds to a charged
+oxygen-on-an-oxygen-site anion, resulting in the formation of a defect complex
+denoted herein as, $\mathrm{{[{O_{O}^{2-}}{H^+}]}^{1-}}$. Formation of an
+$\mathrm{{[{O_{O}^{2-}}{H^+}]}^{1-}}$ defect complex creates a spectrally-broad
+($\sim$0.3 eV FWHM) distribution of electronic states observed in the bandgap
+centered at 0.4 eV above the valence band mobility edge.",2111.08588v1
+2021-11-19,Electrochemical reduction of thin graphene-oxide films in aqueous solutions: restoration of conductivity,"Graphene oxide finds applications in different fields of science, including
+energy conversion. Electrochemical reduction of graphene oxide (GO)
+significantly improves its conductivity. However, the kinetics of this process
+depends on the solvent, supporting electrolyte, pH, and numerous other factors.
+Most studies report the macroscopic views and ex-situ properties of reduced GO.
+To expand the knowledge about GO reduction, in this study, we used cyclic
+voltammetry (CV), simultaneous 2 points and 4 points resistance measurement
+(s24), conductive atomic force microscopy (AFM), and theoretical calculations.
+Using CV, we demonstrated that the choice of supporting electrolyte (KCl or
+LiCl) influences the potential range in which electrochemical GO reduction
+occurs. The activation energy of this process was estimated to be below 30 kJ
+mol-1 in both electrolytes, being significantly lower than that required for
+thermal reduction of GO. Simultaneous in situ s24 resistance measurements
+suggest that GO films reach a highly conductive state at deep negative
+potentials, with an abrupt, irreversible switch from non-conductive to the
+conductive state. However, conductive AFM presents a more exact picture of this
+process: the reduction of GO films starts locally while the formed conductive
+islands grow during the reduction. This mechanism was confirmed by theoretical
+calculations indicating that the reduction starts on isolated oxygen-functional
+groups over the GO basal plane, while clustered OH groups are more difficult to
+reduce. The presented results can help in tailoring reduced GO for a particular
+electrochemical application by precisely controlling the reduction degree and
+percentage of the conductive area of the reduced GO films.",2111.10081v1
+2021-11-22,Chemo-Mechanical Phase-Field Modeling of Iron Oxide Reduction with Hydrogen,"The reduction of iron ore with carbon-carriers is one of the largest sources
+of greenhouse gas emissions in the industry, motivating global activities to
+replace the coke-based blast furnace reduction by hydrogen-based direct
+reduction (HyDR). Iron oxide reduction with hydrogen has been widely
+investigated both experimentally and theoretically. The process includes
+multiple types of chemical reactions, solid state and defect-mediated diffusion
+(by oxygen and hydrogen species), several phase transformations, as well as
+massive volume shrinkage and mechanical stress buildup. In this work, a
+chemo-mechanically coupled phase-field (PF) model has been developed to explore
+the interplay between phase transformation, chemical reaction, species
+diffusion, large elasto-plastic deformation and microstructure evolution.
+Energetic constitutive relations of the model are based on the system free
+energy which is calibrated with the help of a thermodynamic database. The model
+has been first applied to the classical core-shell (w\""ustite-iron) structure.
+Simulations show that the phase transformation from w\""ustite to alpha-iron can
+result in high stress and rapidly decelerating reaction kinetics. Mechanical
+stresses can contribute elastic energy to the system, making phase
+transformation difficult. Thus slow reaction kinetics and low metallization are
+observed. However, if the stress becomes comparatively high, it can shift the
+shape of the free energy from a double-well to a single-well case and speed up
+the transformation. The model has been further applied to simulate an actual
+iron oxide specimen with its complex microstructure, characterized by electron
+microscopy. The simulation results show that isolated pores in the
+microstructure are filled with water vapor during reduction, an effect which
+influences the local reaction atmosphere and dynamics.",2111.11538v1
+2021-11-24,Titanium oxide and chemical inhomogeneity in the atmosphere of the exoplanet WASP-189b,"The temperature of an atmosphere decreases with increasing altitude, unless a
+shortwave absorber exists that causes a temperature inversion. Ozone plays this
+role in the Earth`s atmosphere. In the atmospheres of highly irradiated
+exoplanets, shortwave absorbers are predicted to be titanium oxide (TiO) and
+vanadium oxide (VO). Detections of TiO and VO have been claimed using both low
+and high spectral resolution observations, but later observations have failed
+to confirm these claims or overturned them. Here we report the unambiguous
+detection of TiO in the ultra-hot Jupiter WASP-189b using high-resolution
+transmission spectroscopy. This detection is based on applying the
+cross-correlation technique to many spectral lines of TiO from 460 to 690 nm.
+Moreover, we report detections of metals, including neutral and singly ionised
+iron and titanium, as well as chromium, magnesium, vanadium and manganese (Fe,
+Fe+, Ti, Ti+, Cr, Mg, V, Mn). The line positions of the detected species
+differ, which we interpret as a consequence of spatial gradients in their
+chemical abundances, such that they exist in different regions or dynamical
+regimes. This is direct observational evidence for the three-dimensional
+thermo-chemical stratification of an exoplanet atmosphere derived from
+high-resolution ground-based spectroscopy.",2111.12732v2
+2021-12-12,Honeycomb Layered Oxides With Silver Atom Bilayers and Emergence of Non-Abelian SU(2) Interactions,"Honeycomb layered oxides with monovalent or divalent, monolayered cationic
+lattices generally exhibit myriad crystalline features encompassing rich
+electrochemistry, geometries and disorders, which particularly places them as
+attractive material candidates for next-generation energy storage applications.
+Herein, we report global honeycomb layered oxide compositions, ${\rm
+Ag_2}M_2{\rm TeO_6}$ ($M = \rm Ni, Mg, \textit{etc}.$) exhibiting $\rm Ag$ atom
+bilayers with sub-valent states within Ag-rich crystalline domains of ${\rm
+Ag_6}M_2{\rm TeO_6}$ and $\rm Ag$-deficient domains of ${\rm Ag}_{2 - x}\rm
+Ni_2TeO_6$ ($0 < x < 2$). The $\rm Ag$-rich material characterised by
+aberration-corrected transmission electron microscopy reveals local atomic
+structural disorders characterised by aperiodic stacking and incoherency in the
+bilayer arrangement of $\rm Ag$ atoms. Meanwhile, the global material not only
+displays high ionic conductivity, but also manifests oxygen-hole
+electrochemistry during silver-ion extraction. Within the $\rm Ag$-rich
+domains, the bilayered structure, argentophilic interactions therein and the
+expected $\rm Ag$ sub-valent states ($1/2+, 2/3+, \textit{etc}.$) are
+theoretically understood via spontaneous symmetry breaking of
+SU($2$)$\times$U($1$) gauge symmetry interactions amongst $3$ degenerate
+mass-less chiral fermion states, justified by electron occupancy of silver
+$4d_{z^2}$ and $5s$ orbitals on a bifurcated honeycomb lattice. This implies
+that bilayered frameworks have research applications that go beyond the
+confines of energy storage.",2112.07355v7
+2021-12-23,"Covalent Organic Functionalization of Graphene Nanosheets and Reduced Graphene Oxide via 1,3-Dipolar Cycloaddition of Azomethine Ylide","Organic functionalization of graphene is successfully performed via
+1,3-dipolar cycloaddition of azomethine ylide in the liquid phase. The
+comparison between 1-methyl-2-pyrrolidinone and N,N-dimethylformamide as
+dispersant solvents, and between sonication and homogenization as dispersion
+techniques, proves N,N-dimethylformamide and homogenization as the most
+effective choice. The functionalization of graphene nanosheets and reduced
+graphene oxide is confirmed using different techniques. Among them,
+energy-dispersive X-ray spectroscopy allows to map the pyrrolidine ring of the
+azomethine ylide on the surface of functionalized graphene, while micro-Raman
+spectroscopy detects new features arising from the functionalization, which are
+described in agreement with the power spectrum obtained from ab initio
+molecular dynamics simulation. Moreover, X-ray photoemission spectroscopy of
+functionalized graphene allows the quantitative elemental analysis and the
+estimation of the surface coverage, showing a higher degree of
+functionalization for reduced graphene oxide. This more reactive behavior
+originates from the localization of partial charges on its surface due to the
+presence of oxygen defects, as shown by the simulation of the electrostatic
+features. Functionalization of graphene using 1,3-dipolar cycloaddition is
+shown to be a significant step towards the controlled synthesis of
+graphene-based complex structures and devices at the nanoscale.",2112.12505v1
+2022-01-21,Oldhamite: a new link in mantle for C-O-S-Ca cycles and an indicator for planetary habitability,"In the solar system, oldhamite (CaS) is generally considered to be formed by
+the condensation of solar nebula gas. Enstatite chondrites, one of the most
+important repositories of oldhamite, are believed to be the representative of
+the material which formed Earth. Thus, the formation mechanism and the
+evolution process of oldhamite are of great significance to the deeply
+understanding about the solar nebula, meteorites, the origin of Earth, and the
+C-O-S-Ca cycles of Earth. To date, no report about the oldhamite in the mantle
+exists. However, here we show the formation of oldhamite through the reaction
+between sulfide-bearing orthopyroxenite and molten calcite at 1.5 GPa/1510 K
+and 0.5 GPa/1320 K. Surprisingly the oxygen fugacities in our experiments are
+within the range of mantle conditions, which is 6 orders of magnitude higher
+than that of the solar nebula mechanism. Oldhamite is easily oxidized to
+calcium sulfate. Both low oxygen fugacity of magma and extreme low oxygen
+content of atmosphere are necessary for existence of oldhamite on the surface
+of a planet; otherwise, anhydrite or gypsum will exist in large quantities. The
+widespread existence of oldhamite on the planet surface indicates the planet is
+definitely not habitable because of the scarcity of oxygen. The formation and
+oxidation of oldhamite are accompanied by the production of carbon dioxide and
+the consumption of oxygen, which may have an impact on the Earth atmosphere
+before the Great Oxidation Event and during the Permian-Triassic Boundary.",2201.08615v7
+2022-02-09,General embedded cluster protocol for accurate modeling of oxygen vacancies in metal-oxides,"The O vacancy (Ov) formation energy, $E_\textrm{Ov}$, is an important
+property of a metal-oxide, governing its performance in applications such as
+fuel cells or heterogeneous catalysis. These defects are routinely studied with
+density functional theory (DFT). However, it is well-recognized that standard
+DFT formulations (e.g. the generalized gradient approximation) are insufficient
+for modeling the Ov, requiring higher levels of theory. The embedded cluster
+method offers a promising approach to compute $E_\textrm{Ov}$ accurately,
+giving access to all electronic structure methods. Central to this approach is
+the construction of quantum(-mechanically treated) clusters placed within
+suitable embedding environments. Unfortunately, current approaches to
+constructing the quantum clusters either require large system sizes, preventing
+application of high-level methods, or require significant manual input,
+preventing investigations of multiple systems simultaneously. In this work, we
+present a systematic and general quantum cluster design protocol that can
+determine small converged quantum clusters for studying the Ov in metal-oxides
+with accurate methods such as local coupled cluster with single, double and
+perturbative triple excitations [CCSD(T)]. We apply this protocol to study the
+Ov in the bulk and surface planes of rutile TiO2 and rocksalt MgO, producing
+the first accurate and well-converged determinations of $E_\textrm{Ov}$ with
+this method. These reference values are used to benchmark exchange-correlation
+functionals in DFT and we find that all studied functionals underestimate
+$E_\textrm{Ov}$, with the average error decreasing along the rungs of Jacob's
+ladder. This protocol is automatable for high-throughput calculations and can
+be generalized to study other point defects or adsorbates.",2202.04633v2
+2022-02-17,Advances in honeycomb layered oxides: Part II -- Theoretical advances in the characterisation of honeycomb layered oxides with optimised lattices of cations,"The quest for a successful condensed matter theory that incorporates
+diffusion of cations, whose trajectories are restricted to a
+honeycomb/hexagonal pattern prevalent in honeycomb layered materials is
+ongoing, with the recent progress discussed herein focusing on symmetries,
+topological aspects and phase transition descriptions of the theory. Such a
+theory is expected to differ both qualitatively and quantitatively from 2D
+electron theory on static carbon lattices, by virtue of the dynamical nature of
+diffusing cations within lattices in honeycomb layered materials. Herein, we
+have focused on recent theoretical progress in the characterisation of
+pnictogen- and chalcogen-based honeycomb layered oxides with emphasis on
+hexagonal/honeycomb lattices of cations. Particularly, we discuss the link
+between Liouville conformal field theory to expected experimental results
+characterising the optimal nature of the honeycomb/hexagonal lattices in
+congruent sphere packing problems. The diffusion and topological aspects are
+captured by an idealised model, which successfully incorporates the duality
+between the theory of cations and their vacancies. Moreover, the rather
+intriguing experimental result that a wide class of silver-based layered
+materials form stable Ag bilayers, each comprising a pair of triangular
+sub-lattices, suggests a bifurcation mechanism for the Ag triangular
+sub-lattices, which ultimately requires conformal symmetry breaking within the
+context of the idealised model, resulting in a cation monolayer-bilayer phase
+transition. Other relevant experimental, theoretical and computational
+techniques applicable to the characterisation of honeycomb layered materials
+have been availed for completeness.",2202.10323v5
+2022-03-16,Developing a Chemical and Structural Understanding of the Surface Oxide in a Niobium Superconducting Qubit,"Superconducting thin films of niobium have been extensively employed in
+transmon qubit architectures. Although these architectures have demonstrated
+remarkable improvements in recent years, further improvements in performance
+through materials engineering will aid in large-scale deployment. Here, we use
+information retrieved from secondary ion mass spectrometry and electron
+microscopy to conduct a detailed assessment of the surface oxide that forms in
+ambient conditions for transmon test qubit devices patterned from a niobium
+film. We observe that this oxide exhibits a varying stoichiometry with NbO and
+NbO$_2$ found closer to the niobium film and Nb$_2$O$_5$ found closer to the
+surface. In terms of structural analysis, we find that the Nb$_2$O$_5$ region
+is semicrystalline in nature and exhibits randomly oriented grains on the order
+of 1-2 nm corresponding to monoclinic N-Nb$_2$O$_5$ that are dispersed
+throughout an amorphous matrix. Using fluctuation electron microscopy, we are
+able to map the relative crystallinity in the Nb$_2$O$_5$ region with nanometer
+spatial resolution. Through this correlative method, we observe that amorphous
+regions are more likely to contain oxygen vacancies and exhibit weaker bonds
+between the niobium and oxygen atoms. Based on these findings, we expect that
+oxygen vacancies likely serve as a decoherence mechanism in quantum systems.",2203.08710v3
+2022-05-24,Laser-induced crystallization of copper oxide thin films: A comparison made between Gaussian and chevron-beam profiles provides a clue for the failure of Gaussian-beam profile,"The use of laser with a Gaussian-beam profile is frequently adopted in
+attempts of crystallizing non-single-crystal thin films; however, it merely
+results in the formation of poly-crystal thin films. In this paper, selective
+area crystallization of non-single-crystal copper(II) oxide (CuO) is described.
+The crystallization is induced by laser, laser-induced crystallization, with a
+beam profile in the shape of chevron. The crystallization is verified by the
+exhibition of a transition from a non-single-crystal phase consisting of small
+100 nm x 100 nm grains of CuO to a single-crystal phase of copper(I) oxide
+(Cu2O). The transition is identified by electron back scattering diffraction
+and Raman spectroscopy, which clearly suggests that a single-crystal domain of
+Cu2O with size as large as 5 {\mu}m x 1 mm develops. Provided these
+experimental findings, a theoretical assessment based on a cellular automaton
+model, with the behaviors of localized recrystallization and stochastic
+nucleation, is developed. The theoretical assessment can qualitatively describe
+the laser beam geometry-dependence of vital observable features (e.g., size and
+gross geometry of grains) in the laser-induced crystallization. The theoretical
+assessment predicts that differences in resulting crystallinity, either
+single-crystal or poly-crystal, primarily depend on a geometrical profile with
+which melting of non-single-crystal regions takes place along the laser scan
+direction; concave-trailing profiles yield larger grains which lead to
+single-crystal while convex-trailing profiles results in smaller grains which
+lead to poly-crystal, casting light on the fundamental question Why does a
+chevron-beam profile succeed in producing single-crystal while a Gaussian-beam
+profile fails?",2206.02532v1
+2022-06-27,Effect of cationic chemical disorder on defect formation energies in uranium-plutonium mixed oxides,"At the atomic scale, uranium-plutonium mixed oxides (U,Pu)O_2 are
+characterized by cationic chemical disorder, which entails that U and Pu
+cations are randomly distributed on the cation sublattice. In the present work,
+we study the impact of disorder on point-defect formation energies in (U,Pu)O_2
+using interatomic-potential and Density Functional Theory (DFT+U) calculations.
+We focus on bound Schottky defects (BSD) that are among the most stable defects
+in these oxides. As a first step, we estimate the distance R_D around the BSD
+up to which the local chemical environment significantly affects their
+formation energy. To this end, we propose an original procedure in which the
+formation energy is computed for several supercells at varying levels of
+disorder. We conclude that the first three cation shells around the BSD have a
+non-negligible influence on their formation energy (R_{D} = 7.0 \{AA}). We
+apply then a systematic approach to compute the BSD formation energies for all
+the possible cation configurations on the first and second nearest neighbor
+shells around the BSD. We show that the formation energy can range in an
+interval of 0.97 eV, depending on the relative amount of U and Pu neighboring
+cations. Based on these results, we propose an interaction model that describes
+the effect of nominal and local composition on the BSD formation energy.
+Finally, the DFT+U benchmark calculations show a satisfactory agreement for
+configurations characterized by a U-rich local environment, and a larger
+mismatch in the case of a Pu-rich one. In summary, this work provides valuable
+insights on the properties of BSD defects in (U,Pu)O_2, and can represent a
+valid strategy to study point defect properties in disordered compounds.",2206.13150v1
+2022-06-20,An Investigation into the $HfO_2/Si$ Interface: Materials Science Challenges and their Effects on MOSFET Device Performance,"Since the 1960's when Gordon Moore proposed that the transistor density in
+our electronic devices should double every two years while the cost is halved,
+the semiconductor industry has taken this statement to heart. Over the last few
+decades, no other industry has seen growth even comparably close to that
+experienced by the semiconductors industry. This has all been made possible by
+the unbroken string of ingenious breakthroughs by brilliant minds that have
+been working tirelessly to shrink down transistors. The latest of which is the
+use of high-k dielectrics and a return to metal gates combined with
+3D-transistor architectures. This has been the enabling technology for the
+transition from the 90 nm node to the 45 nm node, allowing us to shrink our
+transistors further without losing additional gate control. The fundamental
+reason for using a high-k gate dielectric compared to SiO2 is that shrinking
+our gate oxide further, which is already at a few angstroms, is no longer a
+feasible option to gain additional gate control. High-k dielectric overcome
+this by exploiting the fundamental physics of capacitors and the materials
+science of dielectrics to provide a viable option to increase gate control
+without the need for successively thinner gate oxides. Hafnium Oxide is the
+most studied and popular of such materials. Its high dielectric constant ~16-25
+and interface stability with silicon at operating temperatures make it an ideal
+candidate for use in current CMOS technology. Despite its deceivingly simple
+appearance, the processes involved in the fabrication of such high-k HfO2/Si
+interfaces are full of process subtleties and nuances. In this term paper we
+hope to explore the physics and materials science of these high-k HfO2/Si
+interfaces, discussing the challenges and ways to overcome them when it comes
+to its actual fabrication, and how this ultimately affects our device
+performance.",2207.13054v1
+2022-08-01,"Sustainable steel through hydrogen plasma reduction of iron ore: process, kinetics, microstructure, chemistry","Fe- and steelmaking is the largest single industrial CO2 emitter, accounting
+for 6.5% of all CO2 emissions on the planet. This fact challenges the current
+technologies to achieve carbon-lean steel production and to align with the
+requirement of a drastic reduction of 80% in all CO2 emissions by around 2050.
+Thus, alternative reduction technologies have to be implemented for extracting
+iron from its ores. The H-based direct reduction has been explored as a
+sustainable route to mitigate CO2 emissions, where the reduction kinetics of
+the intermediate oxide product FexO wustite into Fe is the rate-limiting step
+of the process. The total reaction has an endothermic net energy balance.
+Reduction based on a H plasma may offer an attractive alternative. Here, we
+present a study about the reduction of hematite using H plasma. The evolution
+of both, chemical composition and phase transformations was investigated in
+several intermediate states. We found that hematite reduction kinetics depends
+on the balance between the initial input mass and the arc power. For an
+optimized input mass-arc power ratio, complete reduction was obtained within 15
+min of exposure to the H plasma. The wustite reduction is also the
+rate-limiting step towards complete reduction. Nonetheless, the reduction
+reaction is exothermic, and its rates are comparable with those found in
+H-based direct reduction. Chemical and microstructure analysis revealed that
+the gangue elements partition to the remaining oxide regions, probed by energy
+dispersive spectroscopy and atom probe tomography. Si-enrichment was observed
+in the interdendritic fayalite domains, at the wustite/Fe hetero-interfaces and
+in the primarily solidified oxide particles inside the Fe. With proceeding
+reduction, however, such elements are gradually removed from the samples so
+that the final iron product is nearly free of gangue-related impurities.",2208.00661v1
+2022-09-16,A simple KPFM-based approach for electrostatic-free topographic measurements: the case of MoS$_2$ on SiO$_2$,"A simple implementation of Kelvin probe force microscopy is reported that
+enables recording topographic images in the absence of any component of the
+electrostatic force. Our approach is based on a close loop z-spectroscopy
+operated in data cube mode. Curves of the tip-sample distance as a function of
+time are recorded onto a 2D grid. A dedicated circuit holds the KPFM
+compensation bias and subsequently cut off the modulation voltage during
+well-defined time-windows within the spectroscopic acquisition. Topographic
+images are recalculated from the matrix of spectroscopic curves. This approach
+is applied to the case of transition metal dichalcogenides (TMD) monolayers
+grown by chemical vapour deposition on silicon oxide substrates. In addition,
+we check to what extent a proper stacking height estimation can also be
+performed by recording series of images for decreasing values of the bias
+modulation amplitude. The outputs of both approaches are shown to be fully
+consistent. The results exemplify how in the operating conditions of
+non-contact AFM under ultra-high vacuum, the stacking height values can
+dramatically be overestimated due to variations in the tip-surface capacitive
+gradient, even though the KPFM controller nullifies the potential difference.
+We show that the number of atomic layers of a TMD can be safely assessed, only
+if the KPFM measurement is performed with a modulated bias amplitude reduced at
+its strict minimum or, even better, without any modulated bias. Last, the
+spectroscopic data reveal that defects at the TMD/oxide interface can have a
+counterintuitive impact on the electrostatic landscape, resulting in an
+apparent decrease of the measured stacking height by conventional nc-AFM/KPFM
+compared to non-defective sample areas. Hence, electrostatic free z-imaging
+proves to be a promising tool to assess the existence of defects in atomically
+thin TMD layers grown on oxides",2209.07925v1
+2022-09-26,Lightning-induced chemistry on tidally-locked Earth-like exoplanets,"Determining the habitability and interpreting atmospheric spectra of
+exoplanets requires understanding their atmospheric physics and chemistry. We
+use a 3-D Coupled Climate-Chemistry Model, the Met Office Unified Model with
+the UK Chemistry and Aerosols framework, to study the emergence of lightning
+and its chemical impact on tidally-locked Earth-like exoplanets. We simulate
+the atmosphere of Proxima Centauri b orbiting in the Habitable Zone of its
+M-dwarf star, but the results apply to similar M-dwarf orbiting planets. Our
+chemical network includes the Chapman ozone reactions and hydrogen oxide
+(HO$_{\mathrm{x}}$=H+OH+HO$_2$) and nitrogen oxide
+(NO$_{\mathrm{x}}$=NO+NO$_2$) catalytic cycles. We find that photochemistry
+driven by stellar radiation (177-850 nm) supports a global ozone layer between
+20-50 km. We parameterise lightning flashes as a function of cloud-top height
+and the resulting production of nitric oxide (NO) from the thermal
+decomposition of N$_2$ and O$_2$. Rapid dayside convection over and around the
+substellar point results in lightning flash rates of up to 0.16 flashes
+km$^{-2}$yr$^{-1}$, enriching the dayside atmosphere below altitudes of 20 km
+in NO$_{\mathrm{x}}$. Changes in dayside ozone are determined mainly by UV
+irradiance and the HO$_{\mathrm{x}}$ catalytic cycle. ~45% of the planetary
+dayside surface remains at habitable temperatures (T$_{\mathrm{surf}}$>273.15
+K) and the ozone layer reduces surface UV radiation levels to 15%.
+Dayside-nightside thermal gradients result in strong winds that subsequently
+advect NO$_{\mathrm{x}}$ towards the nightside, where the absence of
+photochemistry allows NO$_{\mathrm{x}}$ chemistry to involve reservoir species.
+Our study also emphasizes the need for accurate UV stellar spectra to
+understand the atmospheric chemistry of exoplanets.",2209.12502v1
+2022-09-27,Investigating the Electronic Structure of Prospective Water-splitting Oxide BaCe$_{0.25}$Mn$_{0.75}$O$_{3-δ}$ Before and After Thermal Reduction,"BaCe$_{0.25}$Mn$_{0.75}$O$_{3-\delta}$ (BCM), a non-stoichiometric oxide
+closely resembling a perovskite crystal structure, has recently emerged as a
+prospective contender for application in renewable energy harvesting by solar
+thermochemical hydrogen generation. Using solar energy, oxygen-vacancies can be
+created in BCM and the reduced crystal so obtained can, in turn, produce H2 by
+stripping oxygen from H2O. Therefore, a first step toward understanding the
+working mechanism and optimizing the performance of BCM, is a thorough and
+comparative analysis of the electronic structure of the pristine and the
+reduced material. In this paper, we probe the electronic structure of BCM using
+the combined effort of first-principles calculations and experimental O K-edge
+x-ray absorption spectroscopy (XAS). The computed projected density-of-states
+(PDOS) and orbital-plots are used to propose a simplified model for
+orbital-mixing between the oxygen and the ligand atoms. With the help of
+state-of-the-art simulations, we are able to find the origins of the XAS peaks
+and to categorize them on the basis of contribution from Ce and Mn. For the
+reduced crystal, the calculations show that, as a consequence of dielectric
+screening, the change in electron-density resulting from the reduction is
+strongly localized around the oxygen vacancy. Our experimental studies reveal a
+marked lowering of the first O K-edge peak in the reduced crystal which is
+shown to result from a diminished O-2p contribution to the frontier unoccupied
+orbitals, in accordance with the tight-binding scheme. Our study paves the way
+for investigation of the working-mechanism of BCM and for computational and
+experimental efforts aimed at design and discovery of efficient water-splitting
+oxides.",2209.13267v1
+2023-01-18,Redox evolution of the crystallizing terrestrial magma ocean and its influence on atmosphere outgassing,"Magma oceans are episodes of large-scale melting of the mantle of terrestrial
+planets. The energy delivered by the Moon-forming impact induced a deep magma
+ocean on the young Earth, corresponding to the last episode of core-mantle
+equilibration. The crystallization of this magma ocean led to the outgassing of
+volatiles initially present in the Earth's mantle, resulting in the formation
+of a secondary atmosphere. During outgassing, the magma ocean acts as a
+chemical buffer for the atmosphere via the oxygen fugacity, set by the
+equilibrium between ferrous- and ferric-iron oxides in the silicate melts. By
+tracking the evolution of the oxygen fugacity during magma ocean
+solidification, we model the evolving composition of a C-O-H atmosphere. We use
+the atmosphere composition to calculate its thermal structure and radiative
+flux. This allows us to calculate the lifetime of the terrestrial magma ocean.
+We find that, upon crystallizing, the magma ocean evolves from a mildly
+reducing to a highly oxidized redox state, thereby transiting from a CO- and
+H2-dominated atmosphere to a CO2- and H2O-dominated one. We find the overall
+duration of the magma ocean crystallization to depend mostly on the bulk H
+content of the mantle, and to remain below 1.5 millions years for up to 9
+Earth's water oceans' worth of H. Our model also suggests that reduced
+atmospheres emit lower infrared radiation than oxidized ones, despite of the
+lower greenhouse effect of reduced species, resulting in a longer magma ocean
+lifetime in the former case. Although developed for a deep magma ocean on
+Earth, the framework applies to all terrestrial planet and exoplanet magma
+oceans, depending on their volatile budgets.",2301.07505v1
+2023-01-22,Demonstration of the etching cobalt oxide grown on the stainless steel as a base metal surface using F2/He dielectric barrier discharge plasma in atmospheric pressure,"Metal surface cleaning or etching techniques using reactive plasma are
+emerging as one of the dry processing techniques for surface contaminants with
+high bond energy, especially for cleaning and decontamination of nuclear
+components and equipment. In this study, the plasma reaction due to the
+discharge of a dielectric barrier of a mixture of 95% helium and 5% fluorine
+with cobalt oxide film grown on the surface of stainless steel 304 was studied
+experimentally. Experimental results show that cobalt oxide becomes a powder
+after plasma irradiation and is easily separated from the surface of the base
+metal. The optimal plasma generating conditions of the dielectric barrier
+discharge (DBD) used in this experimental study were obtained at atmospheric
+pressure, voltage 4.5 kV, and frequency 25 kHz with a etching rate of 10.875
+{\mu}mol/min. The samples were analyzed before and after plasma irradiation,
+using Scanning electron microscopy with energy dispersive X-ray spectroscopy
+(SEM/EDX) and the purification rate was performed using a sequential weighting
+of the samples with scales 10^(-4) grams accurately obtained. The results show
+the ability of this method to effectively remove the surface contamination of
+cobalt from the surface of stainless steel 304.",2301.09065v4
+2023-02-23,X-ray projection imaging of metal oxide particles inside gingival tissues,"There is increasing recognition that oral health affects overall health and
+systemic diseases. Nonetheless it remains challenging to rapidly screen patient
+biopsies for signs of inflammation or the pathogens or foreign materials that
+elicit the immune response. This is especially true in conditions such as
+foreign body gingivitis (FBG), where the foreign particles are often difficult
+to detect. Our long term goal is to establish a method to determine if the
+inflammation of the gingival tissue is due to the presence of a metal oxide,
+with emphasis on elements that were previously reported in FBG biopsies, such
+as silicon dioxide, silica, and titanium dioxide whose persistent presence can
+be carcinogenic. In this paper, we proposed to use multiple energy X-ray
+projection imaging to detect and to differentiate different metal oxide
+particles embedded inside gingival tissues. To simulate the performance of the
+imaging system, we have used GATE simulation software to mimic the proposed
+system and to obtain images with different systematic parameters. The simulated
+parameters include the X-ray tube anode metal, the X-ray spectra bandwidth, the
+X-ray focal spot size, the X-ray photon number, and the X-ray dector pixel. We
+have also applied the de-noising algorithm to obtain better Contrast-to-noise
+ratio (CNR). Our results indicate that it is feasible to detect metal particles
+as small as 0.5 micrometer in diameter when we use a Chromium anode target with
+an energy bandwidth of 5 keV, an X-ray photon number of 10^8, and an X-ray
+detector with a pixel size of 0.5 micrometer and 100 by 100 pixels. We have
+also found that different metal particles could be differentiated from the CNR
+at four different X-ray anodes and spectra. These encouraging initial results
+will guide our future imaging system design.",2302.12310v1
+2023-04-24,New compound and hybrid binding energy sputter model for modeling purposes in agreement with experimental data,"Rocky planets and moons experiencing solar wind sputtering are continuously
+supplying their enveloping exosphere with ejected neutral atoms. To understand
+the quantity and properties of the ejecta, well established Binary Collision
+Approximation Monte Carlo codes like TRIM with default settings are used
+predominantly. Improved models such as SDTrimSP have come forward and together
+with new experimental data the underlying assumptions have been challenged. We
+introduce a hybrid model, combining the previous surface binding approach with
+a new bulk binding model akin to Hofs\""ass & Stegmaier (2023). In addition, we
+expand the model implementation by distinguishing between free and bound
+components sourced from mineral compounds such as oxides or sulfides. The use
+of oxides and sulfides also enables the correct setting of the mass densities
+of minerals, which was previously limited to the manual setting of individual
+atomic densities of elements. All of the energies and densities used are
+thereby based on tabulated data, so that only minimal user input and no fitting
+of parameters are required. We found unprecedented agreement between the newly
+implemented hybrid model and previously published sputter yields for incidence
+angles up to 45{\deg} from surface normal. Good agreement is found for the
+angular distribution of mass sputtered from enstatite MgSiO$_3$ compared to
+latest experimental data. Energy distributions recreate trends of experimental
+data of oxidized metals. Similar trends are to be expected from future mineral
+experimental data. The model thus serves its purpose of widespread
+applicability and ease of use for modelers of rocky body exospheres.",2304.12048v1
+2023-04-28,A comparison of mechanistic models for the combustion of iron microparticles and their application to polydisperse iron-air suspensions,"Metals can serve as carbon-free energy carriers, e. g. in innovative
+metal-metal oxide cycles as proposed by Bergthorson (Prog. Energy Combust.
+Sci., 2018). Iron powder is a suitable candidate since it can be oxidized with
+air. Nevertheless, the combustion of iron powder in air is challenging
+especially with respect to flame stabilization which depends on the particle
+size distribution among other factors. Models for the prediction of reaction
+front speed in iron-air suspensions can contribute to overcoming this
+challenge. To this end, three different models for iron particle oxidation are
+integrated into a laminar flame solver for simulating reaction fronts. The
+scientific objective of this work is to elucidate the influence of
+polydispersity on the reaction front speed, which is still not satisfactorily
+understood. In a systematic approach, cases with successively increasing
+complexity are considered: From single particle combustion to iron-air
+suspensions prescribing binary particle size distributions (PSDs), generic
+PSDs, and a PSD measured for a real iron powder sample. The simulations show
+that, dependent on the PSD, particles undergo thermochemical conversion in a
+sequential manner according to their size and every particle fraction exhibits
+an individual combustion environment. The local environment can be leaner or
+richer than the overall iron-to-air ratio would suggest and can be very
+different from single particle experiments. The contribution of individual
+particle fractions to the overall reaction front speed depends on its ranking
+within the PSD. The study further demonstrates, that although the three
+particle models show good agreement for single particle combustion, they lead
+to very different reaction front speeds. This is due to the different ignition
+behavior predicted by the particle models, which is shown to strongly influence
+the reaction front characteristics.",2304.14927v2
+2023-05-22,A new sulfur bioconversion process development for energy- and space-efficient secondary wastewater treatment,"Harvesting organic matter from wastewater is widely applied to maximize
+energy recovery; however, it limits the applicability of secondary treatment
+for acceptable effluent discharge into surface water bodies. To turn this
+bottleneck issue into an opportunity, this study developed oxygen-induced
+thiosulfatE production duRing sulfATe reductiOn (EARTO) to provide an efficient
+electron donor for wastewater treatment. Typical pretreated wastewater was
+synthesized with chemical oxygen demand of 110 mg/L, sulfate of 50 mg S/L, and
+varying dissolved oxygen (DO) and was fed into a moving-bed biofilm reactor
+(MBBR). The MBBR was operated continuously with a short hydraulic retention
+time of 40 min for 349 days. The formation rate of thiosulfate reached
+0.12-0.18 g S/(m2.d) with a high produced thiosulfate-S/TdS-S ratio of 38-73%
+when influent DO was 2.7-3.6 mg/L. The sludge yield was 0.23-0.29 gVSS/gCOD,
+much lower than it was in conventional activated sludge processes. Then, batch
+tests and metabolism analysis were conducted to confirm the oxygen effect on
+thiosulfate formation, characterize the roles of sulfate and microbial
+activities, and explore the mechanism of oxygen-induced thiosulfate formation
+in ERATO. Results examined that oxygen supply promoted the
+thiosulfate-Sproduced/TdS-Sproduced ratio from 4% to 24-26%, demonstrated that
+sulfate and microbial activities were critical for thiosulfate production, and
+indicated that oxygen induces thiosulfate formation through two pathways: 1)
+direct sulfide oxidation, and 2) indirect sulfide oxidation, sulfide is first
+oxidized to S0 (dominant) which then reacts with sulfite derived from
+oxygen-regulated biological sulfate reduction. The proposed compact ERATO
+process, featuring high thiosulfate production and low sludge production,
+supports space- and energy-efficient secondary wastewater treatment.",2305.13343v1
+2023-05-30,Monocrystalline Si/$β$-Ga$_2$O$_3$ p-n heterojunction diodes fabricated via grafting,"The $\beta$-Ga$_2$O$_3$ has exceptional electronic properties with vast
+potential in power and RF electronics. Despite the excellent demonstrations of
+high-performance unipolar devices, the lack of p-type doping in
+$\beta$-Ga$_2$O$_3$ has hindered the development of Ga$_2$O$_3$-based bipolar
+devices. The approach of p-n diodes formed by polycrystalline p-type oxides
+with n-type $\beta$-Ga$_2$O$_3$ can face severe challenges in further advancing
+the $\beta$-Ga$_2$O$_3$ bipolar devices due to their unfavorable band alignment
+and the poor p-type oxide crystal quality. In this work, we applied the
+semiconductor grafting approach to fabricate monocrystalline
+Si/$\beta$-Ga$_2$O$_3$ p-n diodes for the first time. With enhanced
+concentration of oxygen atoms at the interface of Si/$\beta$-Ga$_2$O$_3$,
+double side surface passivation was achieved for both Si and
+$\beta$-Ga$_2$O$_3$ with an interface Dit value of 1-3 x 1012 /cm2 eV. A
+Si/$\beta$-Ga$_2$O$_3$ p-n diode array with high fabrication yield was
+demonstrated along with a diode rectification of 1.3 x 107 at +/- 2 V, a diode
+ideality factor of 1.13 and avalanche reverse breakdown characteristics. The
+diodes C-V shows frequency dispersion-free characteristics from 10 kHz to 2
+MHz. Our work has set the foundation toward future development of
+$\beta$-Ga$_2$O$_3$-based transistors.",2305.19138v1
+2023-06-22,"Abundance, Major Element Composition and Size of Components and Matrix in CV, CO and Acfer 094 Chondrites","The relative abundances and chemical compositions of the macroscopic
+components or ""inclusions"" (chondrules and refractory inclusions) and
+fine-grained mineral matrix in chondritic meteorites provide constraints on
+astrophysical theories of inclusion formation and chondrite accretion. We
+present new techniques for analysis of low count per pixel Si, Mg, Ca, Al, Ti
+and Fe x-ray intensity maps of rock sections, and apply them to large areas of
+CO and CV chondrites, and the ungrouped Acfer 094 chondrite. For many thousands
+of manually segmented and type-identified inclusions, we are able to assess,
+pixel-by-pixel, the major element content of each inclusion. We quantify the
+total fraction of those elements accounted for by various types of inclusion
+and matrix. Among CO chondrites, both matrix and inclusion Mg to Si ratios
+approach the solar (and bulk CO) ratio with increasing petrologic grade, but Si
+remains enriched in inclusions relative to matrix. The oxidized CV chondrites
+with higher matrix-inclusion ratios exhibit more severe aqueous alteration
+(oxidation), and their excess matrix accounts for their higher porosity
+relative to reduced CV chondrites. Porosity could accommodate an original ice
+component of matrix as the direct cause of local alteration of oxidized CV
+chondrites. We confirm that major element abundances among inclusions differ
+greatly, across a wide range of CO and CV chondrites. These abundances in all
+cases add up to near-chondritic (solar) bulk abundance ratios in these
+chondrites, despite wide variations in matrix-inclusion ratios and inclusion
+sizes: chondrite components are complementary. This ""complementarity"" provides
+a robust meteoritic constraint for astrophysical disk models.",2306.12650v2
+2023-09-03,A Spin-dependent Machine Learning Framework for Transition Metal Oxide Battery Cathode Materials,"Owing to the trade-off between the accuracy and efficiency,
+machine-learning-potentials (MLPs) have been widely applied in the battery
+materials science, enabling atomic-level dynamics description for various
+critical processes. However, the challenge arises when dealing with complex
+transition metal (TM) oxide cathode materials, as multiple possibilities of
+d-orbital electrons localization often lead to convergence to different spin
+states (or equivalently local minimums with respect to the spin configurations)
+after ab initio self-consistent-field calculations, which causes a significant
+obstacle for training MLPs of cathode materials. In this work, we introduce a
+solution by incorporating an additional feature - atomic spins - into the
+descriptor, based on the pristine deep potential (DP) model, to address the
+above issue by distinguishing different spin states of TM ions. We demonstrate
+that our proposed scheme provides accurate descriptions for the potential
+energies of a variety of representative cathode materials, including the
+traditional Li$_x$TMO$_2$ (TM=Ni, Co, Mn, $x$=0.5 and 1.0), Li-Ni anti-sites in
+Li$_x$NiO$_2$ ($x$=0.5 and 1.0), cobalt-free high-nickel
+Li$_x$Ni$_{1.5}$Mn$_{0.5}$O$_4$ ($x$=1.5 and 0.5), and even a ternary cathode
+material Li$_x$Ni$_{1/3}$Co$_{1/3}$Mn$_{1/3}$O$_2$ ($x$=1.0 and 0.67). We
+highlight that our approach allows the utilization of all ab initio results as
+a training dataset, regardless of the system being in a spin ground state or
+not. Overall, our proposed approach paves the way for efficiently training MLPs
+for complex TM oxide cathode materials.",2309.01146v1
+2023-09-03,Oxygen Vacancy Formation Energy in Metal Oxides: High Throughput Computational Studies and Machine Learning Predictions,"The oxygen vacancy formation energy ($\Delta E_{vf}$) governs defect dynamics
+and is a useful metric to perform materials selection for a variety of
+applications. However, density functional theory (DFT) calculations of $\Delta
+E_{vf}$ come at a greater computational cost than the typical bulk calculations
+available in materials databases due to the involvement of multiple
+vacancy-containing supercells. As a result, available repositories of direct
+calculations of $\Delta E_{vf}$ remain relatively scarce, and the development
+of machine learning models capable of delivering accurate predictions is of
+interest. In the present, work we address both such points. We first report the
+results of new high-throughput DFT calculations of oxygen vacancy formation
+energies of the different unique oxygen sites in over 1000 different oxide
+materials, which together form the largest dataset of directly computed oxygen
+vacancy formation energies to date, to our knowledge. We then utilize the
+resulting dataset of $\sim$2500 $\Delta E_{vf}$ values to train random forest
+models with different sets of features, examining both novel features
+introduced in this work and ones previously employed in the literature. We
+demonstrate the benefits of including features that contain information
+specific to the vacancy site and account for both cation identity and oxidation
+state, and achieve a mean absolute error upon prediction of $\sim$0.3 eV/O,
+which is comparable to the accuracy observed upon comparison of DFT
+computations of oxygen vacancy formation energy and experimental results.
+Finally, we demonstrate the predictive power of the developed models in the
+search for new compounds for solar-thermochemical water-splitting applications,
+finding over 250 new AA$^{\prime}$BB$^{\prime}$O$_6$ double perovskite
+candidates.",2309.01160v1
+2023-09-05,Non-volatile optical phase shift in ferroelectric hafnium zirconium oxide,"A non-volatile optical phase shifter is a critical component for enabling
+large-scale, energy-efficient programmable photonic integrated circuits (PICs)
+on a silicon (Si) photonics platform. While ferroelectric materials like BaTiO3
+offer non-volatile optical phase shift capabilities, their compatibility with
+complementary metal-oxide-semiconductor (CMOS) fabs is limited. Hence, the
+search for a novel CMOS-compatible ferroelectric material for non-volatile
+optical phase shifting in Si photonics is of utmost importance. Hafnium
+zirconium oxide (HZO) is an emerging ferroelectric material discovered in 2011,
+which exhibits CMOS compatibility due to the utilization of high-k dielectric
+HfO2 in CMOS transistors. Although extensively studied for ferroelectric
+transistors and memories, its application in photonics remains relatively
+unexplored. Here, we show the optical phase shift induced by ferroelectric HZO
+deposited on a SiN optical waveguide. We observed a negative change in
+refractive index at a 1.55 um wavelength in the pristine device regardless of
+the direction of an applied electric filed. We achieved approximately pi phase
+shift in a 4.5-mm-long device with negligible optical loss. The non-volatile
+multi-level optical phase shift was confirmed with a persistence of > 10000 s.
+This phase shift can be attributed to the spontaneous polarization within the
+HZO film along the external electric field. We anticipate that our results will
+stimulate further research on optical nonlinear effects, such as the Pockels
+effect, in ferroelectric HZO. This advancement will enable the development of
+various devices, including high-speed optical modulators. Consequently,
+HZO-based programmable PICs are poised to become indispensable in diverse
+applications, ranging from optical fiber communication and artificial
+intelligence to quantum computing and sensing.",2309.01967v1
+2023-10-01,Atomic Insights into the Oxidative Degradation Mechanisms of Sulfide Solid Electrolytes,"Electrochemical degradation of solid electrolytes is a major roadblock in the
+development of solid-state batteries, and the formed solid-solid interphase
+(SSI) plays a key role in the performance of solid-state batteries. In this
+study, by combining experimental X-ray absorption spectroscopy (XAS)
+measurements, first-principles simulations, and unsupervised machine learning,
+we have unraveled the atomic-scale oxidative degradation mechanisms of sulfide
+electrolytes at the interface using the baseline Li3PS4 (LPS) electrolyte as a
+model system. The degradation begins with a decrease of Li neighbor affinity to
+S atoms upon initial delithiation, followed by the formation of S-S bonds as
+the PS4 tetrahedron deforms. After the first delithiation cycle, the PS4 motifs
+become strongly distorted and PS3 motifs start to form. Spectral fingerprints
+of the local structural evolution are identified, which correspond to the main
+peak broadening and the peak shifting to a higher energy by about 2.5 eV in P
+K-edge XAS and a new peak emerging at 2473 eV in S K-edge XAS during
+delithiation. The spectral fingerprints serve as a proxy for the
+electrochemical stability of phosphorus sulfide solid electrolytes beyond LPS,
+as demonstrated in argyrodite Li6PS5Cl. We observed that the strong distortion
+and destruction of PS4 tetrahedra and the formation of S-S bonds are correlated
+with an increased interfacial impedance. To the best of our knowledge, this
+study showcases the first atomic-scale insights into the oxidative degradation
+mechanism of the LPS electrolyte, which can provide guidance for controlling
+macroscopic reactions through microstructural engineering and, more generally,
+can advance the rational design of sulfide electrolytes.",2310.00794v1
+2023-09-12,"Innovative NiAl Electrodes for Long-Term, Intermediate High-Temperature SAW Sensing Applications Using LiNbO$_3$ Substrates","Wireless SAW reflective delay line (R-DL) technology is very powerful to
+carry out remote measurements of various parameters under harsh environments,
+while enabling the identification of a given sensor among several of them.
+However, R-DL technology is currently limited to 350$^\circ$C for long-term
+applications, likely because of aluminium electrodes oxidation and/or congruent
+lithium niobate segregation process. In this study, an innovative alloy, namely
+NiAl, is investigated as an alternative to Al to make R-DLs able to withstand
+high temperatures up to 500$^\circ$C on the long term. Indeed, NiAl gathers, in
+the bulk state, all the necessary properties (fairly low electrical resistivity
+and density, high melting temperature and resistance to oxidation). The study
+also examines the extent of the congruent LiNbO$_3$ segregation process, to
+determine its impact on the NiAl/LiNbO$_3$ R-DLs performances. The obtained
+results are very promising. NiAl electrodes self-passivate during the first 50h
+of annealing at 500$^\circ$C: 20 nm-thick Al$_2$O$_3$ layers form at the
+surface and in between the electrodes and the substrate, protecting the
+remaining NiAl layer from further oxidation. Besides, the segregation process
+occurs mainly in the same time. It is located in the first 150-200 nm of the
+substrate. Both phenomena have no significant impact on the performance of
+NiAl/LiNbO$_3$ R-DLs working at 433 MHz. Continuous in-situ electrical
+monitoring of such devices shows a standard deviation of the operating
+frequency of only 1.04 ppm during an annealing process of 250h at 500$^\circ$C.
+Moreover, the time-resolved S11 response of the device at the end of this
+treatment is not degraded at all. Thus, 433 MHz NiAl/LiNbO$_3$ R-DL sensors can
+operate with high fidelity for at least 10 days at 500$^\circ$C under air
+atmosphere, and there are strong signs that their lifetime is actually much
+longer.",2310.11456v1
+2023-10-23,Photoemission study and band alignment of GaN passivation layers on GaInP heterointerface,"III-V semiconductor-based photoelectrochemical (PEC) devices show the highest
+solar-to-electricity or solar-to-fuel conversion efficiencies. GaInP is a
+relevant top photoabsorber layer or a charge-selective contact in PEC for
+integrated and direct solar fuel production, due to its tunable lattice
+constant, electronic band structure, and favorable optical properties. To
+enhance the stability of its surface against chemical corrosion which leads to
+decomposition, we deposit a GaN protection and passivation layer. The n-doped
+GaInP(100) epitaxial layers were grown by metalorganic chemical vapor
+deposition on top of GaAs(100) substrate. Subsequently, thin 1-20 nm GaN films
+were grown on top of the oxidized GaInP surfaces by atomic layer deposition. We
+studied the band alignment of these multi-junction heterostructures by X-ray
+and ultraviolet photoelectron spectroscopy. Due to the limited emission depth
+of photoelectrons, we determined the band alignment by a series of separate
+measurements in which we either modified the GaInP(100) surface termination or
+the film thickness of the grown GaN on GaInP(100) buffer layers. On
+n-GaInP(100) surfaces prepared with the well-known phosphorus-rich (2x2)/c(4x2)
+reconstruction we found up-ward surface band bending (BB) of 0.34 eV, and Fermi
+level pinning due to the present surface states. Upon oxidation, the surface
+states are partially passivated resulting in a reduction of BB to 0.12 eV and a
+valence band offset (VBO) between GaInP and oxide bands of 2.0 eV. Between the
+GaInP(100) buffer layer and the GaN passivation layer, we identified a VBO of
+1.8 eV. The corresponding conduction band offset of -0.2 eV is found to be
+rather small. Therefore, we evaluate the application of the GaN passivation
+layer as a promising technological step not only to reduce surface states but
+also to increase the stability of the surfaces of photoelectrochemical devices.",2310.15212v1
+2023-11-17,Conformal TiO$_2$ aerogel-like films by plasma deposition: from omniphobic antireflective coatings to perovskite solar cells photoelectrodes,"The ability to control porosity in oxide thin films is one of the key factors
+that determine their properties. Despite the abundance of dry processes for the
+synthesis of oxide porous layers, the high porosity range is typically achieved
+by spin-coating-based wet chemical methods. Besides, special techniques such as
+supercritical drying are required to replace the pore liquid with air while
+maintaining the porous network. In this study, we propose a new method for the
+fabrication of ultra-porous titanium dioxide thin films at room or mild
+temperatures (T lower or equal to 120 degrees Celsius) by the sequential
+process involving plasma deposition and etching. These films are conformal to
+the substrate topography even for high-aspect-ratio substrates and show
+percolated porosity values above 85 percent that are comparable to advanced
+aerogels. The films deposited at room temperature are amorphous. However, they
+become partly crystalline at slightly higher temperatures presenting a
+distribution of anatase clusters embedded in the sponge-like structure.
+Surprisingly, the porous structure remains after annealing the films at 450
+degrees Celsius in air, which increases the fraction of the embedded anatase
+nanocrystals. The films are antireflective, omniphobic, and photoactive
+becoming super-hydrophilic subjected to UV light irradiation The supported
+percolated nanoporous structure can be used as an electron-conducting electrode
+in perovskite solar cells. The properties of the cells depend on the aerogel
+film thickness reaching efficiencies close to those of commercial mesoporous
+anatase electrodes. This generic solvent-free synthesis is scalable and is
+applicable to ultra-high porous conformal oxides of different compositions with
+potential applications in photonics, optoelectronics, energy storage, and
+controlled wetting.",2311.10839v1
+2023-12-07,High-throughput study of the phase constitution of the thin film system Mg-Mn-Al-O in relation to Li recovery from slags,"The increasing importance of recycling makes the recovery of valuable
+elements from slags interesting, e.g., by the concept of engineered artificial
+minerals (EnAMs). In this concept, it is aimed for the formation of EnAMs,
+meaning phase(s) with a high content of the to-be-recovered element(s) from
+slags of pyrometallurgical recycling processes. For this, understanding the
+phase constitution of the slag systems is of high importance. The system
+Mg-Mn-Al-O is a metal oxide slag subsystem from Li-ion battery recycling, that
+is critical for the formation of spinel phases, which are competing phases to
+the possible Li-containing EnAM phase LiAlO2. Here, the phase constitution was
+investigated using a thin film materials library that covers the composition
+space (Mg14-69Mn11-38Al14-74)Ox. By means of high-throughput energy-dispersive
+X-ray spectroscopy and X-ray diffraction, the formation of the spinel solid
+solution phase was confirmed for a wide composition space. Increasing
+preferential orientation of the spinel solid solution along (400) with
+increasing Mg content was identified. X-ray photoelectron spectroscopy was used
+to measure the near-surface composition of selected areas of the materials
+library, and detailed peak fitting of the Mn 2p3/2 region revealed the Mn
+oxidation state to be a mixture of Mn2+ and Mn3+. For one measurement area of
+the materials library containing equal atomic amounts of Mg, Mn and Al,
+transmission electron microscopy showed that the approximately 420 nm-thick
+film consists of columnar spinel grains with Mg, Mn and Al being evenly
+distributed. Based on these results, we suggest that the shown high likelihood
+of spinel formation in slags might be influenced by controlling the Mn
+oxidation state to enable the formation of desirable EnAM phases.",2312.04146v1
+2023-12-29,Bilayer Vanadium Dioxide Thin Film with Elevated Transition Temperatures and High Resistance Switching,"Despite widespread interest in the phase-change applications of vanadium
+dioxide (VO$_2$), the fabrication of high-quality VO$_2$ thin films with
+elevated transition temperatures (TIMT) and high Insulator-Metal-Transition
+resistance switching still remains a challenge. This study introduces a
+two-step atmospheric oxidation approach to fabricate bilayer VO$_{2-x}$/VO$_2$
+films on a c-plane sapphire substrate. To quantify the impact of the VO$_2$
+buffer layer, a single-layer VO$_2$ film of the same thickness was also
+fabricated. The bilayer VO$_{2-x}$/VO$_2$ films wherein the top VO$_{2-x}$ film
+was under-oxidized demonstrated an elevation in TIMT reaching ~97 $^\circ$C,
+one of the highest reported to date for VO$_2$ films and is achieved in a
+doping-free manner. Our results also reveal a one-order increase in resistance
+switching, with the optimum bilayer VO$_2$/VO$_2$ film exhibiting ~3.6 orders
+of switching from 25 $^\circ$C to 110 $^\circ$C, compared to the optimum
+single-layer VO$_2$ reference film. This is accompanied by a one-order decrease
+in the on-state resistance in its metallic phase. The elevation in TIMT,
+coupled with increased strain extracted from the XRD characterization of the
+bilayer film, suggests the possibility of compressive strain along the c-axis.
+These VO$_{2-x}$/VO$_2$ films also demonstrate a significant change in the
+slope of their resistance vs temperature curves contrary to the conventional
+smooth transition. This feature was ascribed to the rutile/monoclinic
+quasi-heterostructure formed due to the top VO$_{2-x}$ film having a reduced
+TIMT. Our findings carry significant implications for both the lucid
+fabrication of VO$_2$ thin film devices as well as the study of phase
+transitions in correlated oxides.",2312.17437v1
+2024-01-05,Vanadium oxide clusters in substellar atmospheres: A quantum chemical study,"We aim to understand the formation of cloud condensation nuclei in
+oxygen-rich substellar atmospheres by calculating fundamental properties of the
+energetically most favorable vanadium oxide molecules and clusters. A
+hierarchical optimization approach is applied in order to find the most
+favorable structures for clusters of (VO)$_{N}$ and (VO$_2$)$_{N}$ for N=1-10,
+and (V$_2$O$_5$)$_{N}$ for N=1-4 and to calculate their thermodynamical
+potentials. The candidate geometries are initially optimized applying classical
+interatomic potentials and then refined at the B3LYP/cc-pVTZ level of theory to
+obtain accurate zero-point energies and thermochemical quantities. We present
+previously unreported vanadium oxide cluster structures as lowest-energy
+isomers. We report revised cluster energies and their thermochemical
+properties. Chemical equilibrium calculations are used to asses the impact of
+the updated and newly derived thermodynamic potentials on the gas-phase
+abundances of vanadium-bearing species. In chemical equilibrium, larger
+clusters from different stoichiometric families are found to be the most
+abundant vanadium-bearing species for temperatures below ~1000 K, while
+molecular VO is the most abundant between ~1000 K and ~2000 K. We determine the
+nucleation rates of each stoichiometric family for a given (T$_{gas}$,
+p$_{gas}$) profile of a brown dwarf using classical and non-classical
+nucleation theory. Small differences in the revised Gibbs free energies of the
+clusters have a large impact on the abundances of vanadium bearing species in
+chemical equilibrium at temperatures below ~1000 K, which subsequently has an
+impact on the nucleation rates of each stoichiometric family. We find that with
+the revised and more accurate cluster data non-classical nucleation rates are
+up to 15 orders of magnitude higher than classical nucleation rates.",2401.02784v1
+2024-01-16,The rheology of ultra-high molecular weight poly(ethylene oxide) dispersed in a low molecular weight carrier,"Gel spinning is the industrial method of choice for combining hydrophilic
+ultra-high molecular weight (UHMW) polymer resins with a hydrophobic support
+polymer to produce composite filaments for cytapheresis. Cytapheresis is a
+medical technique for removal of leukocytes from blood. Gel spinning is used to
+avoid high melt viscosity and thermal sensitivity of UHMW resins and the high
+melt temperature of the substrate resin but requires the recovery of toxic
+solvents. The UHMW resin is used because it forms a stable gel phase in the
+presence of water; a lower molecular weight resin (LMW) simply dissolves. UHMW
+and LMW resins were both poly(ethylene oxide) (PEO) and the substrate was
+polyarylsulfone (PAS). The literature indicated PEO undergoes non-oxidative
+thermal degradation above 200 {\deg}C and PAS is processed up to 350 {\deg}C.
+Dynamic oscillatory shear rheometry was used to study 0, 25, 40, 50, 60, and 75
+wt. % UHMW PEO in LMW PEO to take advantage of the sensitivity of viscosity to
+changes in molecular weight and material configuration, indicating degradation.
+Samples were exposed to 220 {\deg}C, 230 {\deg}C, 240 {\deg}C, 250 {\deg}C, 275
+{\deg}C, and 300 {\deg}C temperatures for 5 min to explore conditions that
+could result in sample degradation. The viscosity decreased less with
+increasing UHMW PEO content for samples exposed to the same temperature and the
+viscosity decreased more with increasing exposure temperature for samples with
+the same UHMW PEO content. Parameters were regressed from observed data to
+predict the change in molecular weight via empiricisms relating the viscosity
+to molecular weight, shear rate, temperature, and time.",2401.08816v1
+2024-01-25,"An atomically efficient, highly stable and redox active Ce0.5Tb0.5Ox (3% mol.)/MgO catalyst for total oxidation of methane","Redox and catalytic performance in total methane oxidation of a
+nonostructured ceria-terbia catalyst supported on magnesia is presented and
+compared to that of a pure ceria catalyst supported on MgO. The investigated
+material, Ce0.5Tb0.5Ox (3% mol.)/MgO, features several remarkable properties: a
+quite low total molar loading of the two lanthanide elements, high
+reducibility, as well as very high oxygen storage capacity al low temperatures
+and higher activity than MgO-supported ceria. In terms of lanthanide atomic
+content the catalytic performance of Ce0.5Tb0.5Ox (3% mol.)/MgO largely
+improves compared to that of bulk type ceria and ceria-magnesia solid
+solutions. Such a behavior implies proper optimization of the usage of
+lanthanide elements. A second contribution to atomic economy in the catalyst
+design relates to the fact that the new formulation demonstrate a stabilyty in
+the redox and catalytic performance against very high temperature treatments.
+An investigation on the structure of both the fresh and high-temperature-aged
+catalyst at the atomic scale by means of complementary aberration corrected
+microscopy techniques, reveals the ocuurrence of a variety of exotic,
+lanthanide-containing nanostructures, which span fron isolated, atomically
+dispersed Ln species to nonometer-sized CeTbO2-x patches, extended CeTbO2-x
+bilayers and 2D CeTbO2-x nanoparticles. Nanoanalytical results evidence the
+mixing of the two lanthanides at atomic levels in these nanostructures. The
+combined effects of nanostructuring, mixing of the lanthanides at the atomic
+level, and interaction with the MgO oxide are the roots of the improvement in
+funtional, redox and catalytic properties of the novel Ce0.5Tb0.5Ox (3%
+mol.)/MgO catalyst.",2401.14105v1
+2024-01-30,Carrier-phase DNS of ignition and combustion of iron particles in a turbulent mixing layer,"Three-dimensional CP-DNS of reacting iron particle dust clouds in a turbulent
+mixing layer are conducted. The simulation approach considers the Eulerian
+transport equations for the reacting gas phase and resolves all scales of
+turbulence, whereas the particle boundary layers are modelled employing the
+Lagrangian point-particle framework for the dispersed phase. The CP-DNS employs
+an existing sub-model for iron particle combustion that considers the oxidation
+of iron to FeO and that accounts for both diffusion- and kinetically-limited
+combustion. At first, the particle sub-model is validated against experimental
+results for single iron particle combustion considering various particle
+diameters and ambient oxygen concentrations. Subsequently, the CP-DNS approach
+is employed to predict iron particle cloud ignition and combustion in a
+turbulent mixing layer. The upper stream of the mixing layer is initialised
+with cold particles in air, while the lower stream consists of hot air flowing
+in the opposite direction. Simulation results show that turbulent mixing
+induces heating, ignition and combustion of the iron particles. Significant
+increases in gas temperature and oxygen consumption occur mainly in regions
+where clusters of iron particles are formed. Over the course of the oxidation,
+the particles are subjected to different rate-limiting processes. While
+initially particle oxidation is kinetically-limited it becomes
+diffusion-limited for higher particle temperatures and peak particle
+temperatures are observed near the fully-oxidised particle state. Comparing the
+present non-volatile iron dust flames to general trends in volatile-containing
+solid fuel flames, non-vanishing particles at late simulation times and a
+stronger limiting effect of the local oxygen concentration on particle
+conversion is found for the present iron dust flames in shear-driven
+turbulence.",2401.16944v1
+2024-02-09,High-Resolution X-Ray Spectroscopy of Interstellar Iron Toward Cygnus X-1 and GX 339-4,"We present a high-resolution spectral study of Fe L-shell extinction by the
+diffuse interstellar medium (ISM) in the direction of the X-ray binaries Cygnus
+X-1 and GX 339-4, using the XMM-Newton reflection grating spectrometer. The
+majority of interstellar Fe is suspected to condense into dust grains in the
+diffuse ISM, but the compounds formed from this process are unknown. Here, we
+use the laboratory cross sections from Kortright & Kim (2000) and Lee et al.
+(2009) to model the absorption and scattering profiles of metallic Fe, and the
+crystalline compounds fayalite (Fe$_2$SiO$_4$), ferrous sulfate (FeSO$_4$),
+hematite ($\alpha$-Fe$_2$O$_3$), and lepidocrocite ($\gamma$-FeOOH), which have
+oxidation states ranging from Fe$^{0}$ to Fe$^{3+}$. We find that the observed
+Fe L-shell features are systematically offset in energy from the laboratory
+measurements. An examination of over two dozen published measurements of Fe
+L-shell absorption finds a 1-2 eV scatter in energy positions of the L-shell
+features. Motivated by this, we fit for the best energy-scale shift
+simultaneously with the fine structure of the Fe L-shell extinction cross
+sections. Hematite and lepidocrocite provide the best fits ($\approx +1.1$ eV
+shift), followed by fayalite ($\approx +1.8$ eV shift). However, fayalite is
+disfavored, based on the implied abundances and knowledge of ISM silicates
+gained by infrared astronomical observations and meteoritic studies. We
+conclude that iron oxides in the Fe$^{3+}$ oxidation state are good candidates
+for Fe-bearing dust. To verify this, new absolute photoabsorption measurements
+are needed on an energy scale accurate to better than 0.2 eV.",2402.06726v1
+2024-03-21,Investigation of Genomic Effect of Zirconium Oxide Nanoparticles in Escherichia coli Bacteria,"Due to the concerns of the society about the increase of antibiotic resistant
+infections, many studies and research have been done on nanoparticles and
+applications of nano-biotechnology. Zirconium Oxide ($\text{ZrO}_{2}$) in which
+called zirconia, is a white oxide of zirconium metal that its diameter is 20
+nm. The colloidal size of these particles is often smaller than bacterial and
+eukaryotic cells. The main intention of this paper is to investigate the effect
+of different doses of $\text{ZrO}_{2}$ NPs on the sequences changes for the
+$\textit{Escherichia coli}$ ($\textit{E. coli}$) genome. At the first step,
+$\textit{E. coli}$ was cultured in eosin methylene blue agar and brain heart
+broth (BHB) mediums, respectively. Then, bacteria were treated with
+$\text{ZrO}_{2}$ NPs at concentrations of 100, 250, and 350 $\mu$g/ml. After
+treatment, the growth of bacteria was evaluated by utilizing spectrophotometry
+at 600 nm after incubation times including 2, 4, 6, 8, and 24 hours at 37
+$^{\circ}$C. At the second step, the extraction of DNA was performed by using
+control and treated samples. Then, the changes in the sequence of bacterial
+genome were investigated using RAPD markers. Finally, NTSYS-PC platform was
+employed in order to analyze of the results extracted by electrophoresis of
+products on agarose gel. In this paper, it was observed that $\text{ZrO}_{2}$
+NPs can inhibit the growth of bacteria at concentrations of 250 and 350
+$\mu$g/ml after 8 hours of treatment. It was also found that the
+$\text{ZrO}_{2}$ NPs at different concentrations have not changed the genome
+sequence of $\textit{E. coli}$. Furthermore, it was concluded that the
+$\text{ZrO}_{2}$ NPs with the concentration of 350 $\mu$g/ml had the highest
+inhibitory properties without significant changing in the genomic sequence of
+$\textit{E. coli}$.",2403.14728v1
+2002-11-03,Magnetically induced signatures in a thin film superconductor,"We study the interaction between a one dimensional magnetic nanostructure and
+a thin film superconductor. It is shown that different magnetic distributions
+produce characteristic magnetic field signatures. Moreover, the magnetic
+structure can induce a weak link in the superconducting film, or be positioned
+directly above a predefined nonsuperconducting weak link. We estimate the
+magnetic flux associated with such a structure, and discuss a general
+expression for the energy calculated within the London model.",0211043v1
+2004-09-25,Nano-mechanical magnetization reversal,"The dynamics of the ferromagnetic order parameter in thin magnetic films is
+strongly affected by the magnetomechanical coupling at certain resonance
+frequencies. By solving the equation of motion of the coupled mechanical and
+magnetic degrees of freedom we show that the magnetic-field induced
+magnetization switching can be strongly accelerated by the lattice and
+illustrate the possibility of magnetization reversal by mechanical actuation.",0409681v1
+2005-10-26,Ferroelectricity in spiral magnets,"It was recently observed that materials showing most striking multiferroic
+phenomena are frustrated spin-density-wave magnets. We present a simple
+phenomenological theory, which describes the orientation of the induced
+electric polarization for various incommensurate magnetic states, its
+dependence on temperature and magnetic field, and anomalies of dielectric
+susceptibility at magnetic transitions. We show that electric polarization can
+be induced at domain walls and that magnetic vortices carry electric charge.",0510692v1
+2007-07-13,Magnetic Flux Effects in Statistical Magnetism of Electron Gas,"The effects of magnetic flux in statistical magnetisms, including Pauli
+paramagnetism, Landau diamagnetism, and De Hass-van Alphen oscillation, are
+discussed. It is shown that the diamagnetism could be much increased by the
+fractional magnetic flux, and the amplitude of the magnetic oscillation of De
+Hass-van Alphen can be amplified by the quantum effect of the flux.",0707.1920v1
+2008-05-18,Effect of spin diffusion on spin torque in magnetic nanopillars,"We present systematic magnetoelectronic measurements of magnetic nanopillars
+with different structures of polarizing magnetic layers. The magnetic reversal
+at small magnetic field, the onset of magnetic dynamics at larger field, and
+the magnetoresistance exhibit a significant dependence on the type of the
+polarizing layer. We performed detailed quantitative modeling showing that the
+differences can be explained by the effects of spin-dependent electron
+diffusion.",0805.2706v1
+2012-06-05,Negative magnetic relaxation in superconductors,"It was observed that the trapped magnetic moment of HTS tablets or annuli
+increases in time (negative relaxation) if they are not completely magnetized
+by a pulsed magnetic field. It is shown, in the framework of the Bean
+critical-state model, that the radial temperature gradient appearing in tablets
+or annuli during a pulsed field magnetization can explain the negative magnetic
+relaxation in the superconductor.",1206.0861v1
+2016-08-19,Vesicles in magnetic fields,"Liposome vesicles tend to align with an applied magnetic field. This is due
+to the directional magnetic susceptibility difference of the lipids which form
+the membrane of these vesicles. In this work a model of liposome vesicles
+exposed to magnetic field is presented. Starting from the base energy of a
+lipid membrane in a magnetic field, the force applied to the surrounding fluids
+is derived. This force is then used to investigate the dynamics of vesicle in
+the presence of magnetic fields.",1608.05587v1
+2012-11-20,Magnetic Cluster Excitations,"Magnetic clusters, i.e., assemblies of a finite number (between two or three
+and several hundred) of interacting spin centers which are magnetically
+decoupled from their environment, can be found in many materials ranging from
+inorganic compounds, magnetic molecules, artificial metal structures formed on
+surfaces to metalloproteins. The magnetic excitation spectra in them are
+determined by the nature of the spin centers, the nature of the magnetic
+interactions, and the particular arrangement of the mutual interaction paths
+between the spin centers. Small clusters of up to four magnetic ions are ideal
+model systems to examine the fundamental magnetic interactions which are
+usually dominated by Heisenberg exchange, but often complemented by anisotropic
+and/or higher-order interactions. In large magnetic clusters which may
+potentially deal with a dozen or more spin centers, the possibility of novel
+many-body quantum states and quantum phenomena are in focus. In this review the
+necessary theoretical concepts and experimental techniques to study the
+magnetic cluster excitations and the resulting characteristic magnetic
+properties are introduced, followed by examples of small clusters demonstrating
+the enormous amount of detailed physical information which can be retrieved.
+The current understanding of the excitations and their physical interpretation
+in the molecular nanomagnets which represent large magnetic clusters is then
+presented, with an own section devoted to the subclass of the single-molecule
+magnets which are distinguished by displaying quantum tunneling of the
+magnetization. Finally, some quantum many-body states are summarized which
+evolve in magnetic insulators characterized by built-in or field-induced
+magnetic clusters. The review concludes addressing future perspectives in the
+field of magnetic cluster excitations.",1211.4688v1
+2014-01-08,Generating buoyant magnetic flux ropes in solar-like convective dynamos,"Our Sun exhibits strong convective dynamo action which results in magnetic
+flux bundles emerging through the stellar surface as magnetic spots.
+Global-scale dynamo action is believed to generate large-scale magnetic
+structures in the deep solar interior through the interplay of convection,
+rotation, and shear. Portions of these large-scale magnetic structures are then
+believed to rise through the convective layer, forming magnetic loops which
+then pierce the photosphere as sunspot pairs. Previous global simulations of 3D
+MHD convection in rotating spherical shells have demonstrated mechanisms
+whereby large-scale magnetic wreaths can be generated in the bulk of the
+convection zone. Our recent simulations have achieved sufficiently high levels
+of turbulence to permit portions of these wreaths to become magnetically
+buoyant and rise through the simulated convective layer through a combination
+of magnetic buoyancy and advection by convective giant cells. These buoyant
+magnetic loops are created in the bulk of the convective layer as strong
+Lorentz force feedback in the cores of the magnetic wreaths dampen small-scale
+convective motions, permitting the amplification of local magnetic energies to
+over 100 times the local kinetic energy. While the magnetic wreaths are largely
+generated the shearing of axisymmetric poloidal magnetic fields by axisymmetric
+rotational shear (the $\Omega$-effect), the loops are amplified to their peak
+field strengths before beginning to rise by non-axisymmetric processes. This
+further extends and enhances a new paradigm for the generation of emergent
+magnetic flux bundles, which we term turbulence-enabled magnetic buoyancy.",1401.1826v1
+2014-07-15,Magnetic nanoparticle traveling in external magnetic field,"A set of equations describing the motion of a free magnetic nanoparticle in
+an external magnetic field in a vacuum, or in a medium with negligibly small
+friction forces is postulated. The conservation of the total particle momentum,
+i.e. the sum of the mechanical and the total spin momentum of the nanoparticle
+is taken into account explicitly. It is shown that for the motion of a
+nanoparticle in uniform magnetic field there are three different modes of
+precession of the unit magnetization vector and the director that is parallel
+the particle easy anisotropy axis. These modes differ significantly in the
+precession frequency. For the high-frequency mode the director points
+approximately along the external magnetic field, whereas the frequency and the
+characteristic relaxation time of the precession of the unit magnetization
+vector are close to the corresponding values for conventional ferromagnetic
+resonance. On the other hand, for the low-frequency modes the unit
+magnetization vector and the director are nearly parallel and rotate in unison
+around the external magnetic field. The characteristic relaxation time for the
+low-frequency modes is remarkably long. This means that in a rare assembly of
+magnetic nanoparticles there is a possibility of additional resonant absorption
+of the energy of alternating magnetic field at a frequency that is much smaller
+compared to conventional ferromagnetic resonance frequency. The scattering of a
+beam of magnetic nanoparticles in a vacuum in a non-uniform external magnetic
+field is also considered taking into account the precession of the unit
+magnetization vector and director.",1407.3964v1
+2014-05-05,The magnetic shielding for the neutron decay spectrometer aSPECT,"Many experiments in nuclear and neutron physics are confronted with the
+problem that they use a superconducting magnetic spectrometer which potentially
+affects other experiments by their stray magnetic field. The retardation
+spectrometer aSPECT consists, inter alia, of a superconducting magnet system
+that produces a strong longitudinal magnetic field of up to 6.2T. In order not
+to disturb other experiments in the vicinity of aSPECT, we had to develop a
+magnetic field return yoke for the magnet system. While the return yoke must
+reduce the stray magnetic field, the internal magnetic field and its
+homogeneity should not be affected. As in many cases, the magnetic shielding
+for aSPECT must manage with limited space. In addition, we must ensure that the
+additional magnetic forces on the magnet coils are not destructive. In order to
+determine the most suitable geometry for the magnetic shielding for aSPECT, we
+simulated a variety of possible geometries and combinations of shielding
+materials of non-linear permeability. The results of our simulations were
+checked through magnetic field measurements both with Hall and nuclear magnetic
+resonance probes. The experimental data are in good agreement with the
+simulated values: The mean deviation from the simulated exterior magnetic field
+is (-1.7+/-4.8)%. However, in the two critical regions, the internal magnetic
+field deviates by 0.2% respectively <1E-4 from the simulated values.",1405.0957v1
+2018-12-30,Magnetic properties of an antiferromagnetic spin-1/2 XYZ model in the presence of different magnetic fields: finite-size effects of inhomogeneity property,"Magnetic and thermodynamic properties of the anisotropic XYZ spin-1/2 finite
+chain under both homogeneous and inhomogeneous magnetic fields are
+theoretically studied at low temperature. Using exact diagonalization method
+(ED), we study the magnetization, magnetic susceptibility and specific heat of
+the model characterized in terms of the finite correlation length in the
+presence of three different magnetic fields including longitudinal, transverse
+and transverse staggered magnetic fields. The magnetization, susceptibility and
+the specific heat of the model are investigated under two conditions
+separately: I) when the model is putted in the presence of homogeneous magnetic
+fields; II) when finite inhomogeneities are considered for all applied magnetic
+fields in the Hamiltonian. We show that for the finite-size XYZ chains at low
+temperature, the evident magnetization plateaus gradually convert to their
+counterpart quasi-plateaus when the transverse magnetic field increases.
+Moreover, the influence of the transverse and staggered transverse magnetic
+fields, and their corresponding inhomogeneities on the magnetization process,
+magnetic susceptibility, and specific heat are reported in detail. Our exact
+results illustrate that by altering the inhomogeneity parameters, magnetization
+plateaus gradually convert to their counterpart quasi-plateaus. The specific
+heat manifests Schottky-type maximum, double-peak and triple-peak, as well as,
+transformation between them by varying considered inhomogeneity parameters in
+the Hamiltonian.",1812.11468v2
+2019-04-18,Insight into the magnetic behavior of Sr$_2$IrO$_4$:A spontaneous magnetization study,"Sr$_2$IrO$_4$ is a weak ferromagnet where the spin arrangement is canted
+anti-ferromagnetic (AF). Moreover, the spin-structure coupling plays and
+important role in magnetic behavior of Sr$_2$IrO$_4$. In this concern the
+magnetization under zero applied field i.e. spontaneous magnetization would be
+interesting to study and would give insight into the novel magnetic behavior of
+Sr$_2$IrO$_4$. Sophisticated techniques like neutron diffraction, $\mu$
+\textit{SR} etc has been used to understand the magnetic behavior of
+Sr$_2$IrO$_4$ under zero applied field. To understand the magnetic behavior we
+have performed detail field and temperature dependent magnetization study, the
+measured field and temperature dependent magnetic data is analyzed rigorously.
+We have attempted the understand the temperature dependance of spontaneous
+magnetization, remanent magnetization and coercive force. We observe that the
+spontaneous magnetization extracted from Arrott plot shows that the
+Sr$_2$IrO$_4$ is not an ideal ferromagnet. The temperature dependent coercive
+field is found to follows Guant's model of strong domain wall pinning. Our
+investigation explicit the temperature dependence of various magnetic
+properties shows the magnetic transitions from paramagnetic to ferromagnetic
+phase with $T_c$ around 225 K and a low temperature evolution of magnetic
+magnetic moment around $T_M$ $\sim$90 K.",1904.08792v1
+2021-09-24,Fluidic Endogenous Magnetism and Magnetic Monopole Clues from Liquid Metal Droplet Machine,"Magnetism and magnetic monopole are classical issues in basic physics.
+Conventional magnets are generally composed of rigid materials with shapes and
+structures unchangeable which may face challenges sometimes to answer the above
+questions. Here, from an alternative other than rigid magnet, we disclosed an
+unconventional way to generate endogenous magnetism and then construct magnetic
+monopole through tuning liquid metal machine. Through theoretical
+interpretation and conceptual experiments, we illustrated that when gallium
+base liquid metal in solution rotates under actuation of an external electric
+field, it forms an endogenous magnetic field inside which well explains the
+phenomenon that two such discrete metal droplets could easily fuse together,
+indicating their reciprocal attraction via N and S poles. Further, we conceived
+that the self-driving liquid metal motor was also an endogenous magnet owning
+the electromagnetic homology. When liquid metal in solution swallowed aluminum
+inside, it formed a spin motor and dynamically variable charge distribution
+which produced an endogenous magnetic field. This finding explains the
+phenomena that there often happened reflection collision and attraction fusion
+between running liquid metal motors which were just caused by the dynamic
+adjustment of their N and S polarities. Finally, we conceived that such
+endogenous magnet could lead to magnetic monopole and four technical routes
+were suggested as: 1. Matching the interior flow field of liquid metal
+machines; 2. Superposition between external electric effect and magnetic field;
+3. Composite construction between magnetic particles and liquid metal motor; 4.
+Chemical ways such as via galvanic cell reaction. Overall, the fluidic
+endogenous magnet and the promising magnetic monopole it enabled may lead to
+unconventional magnetoelectric devices and applications in the near future.",2111.02867v1
+2023-09-21,Integrable Magnetic Fluid Hyperthermia Systems for 3D Magnetic Particle Imaging,"Background: Combining magnetic particle imaging (MPI) and magnetic fluid
+hyperthermia (MFH) offers the ability to perform localized hyperthermia and
+magnetic particle imaging-assisted ther-mometry of hyperthermia treatment. This
+allows precise regional selective heating inside the body without invasive
+interventions. In current MPI-MFH platforms, separate systems are used, which
+require object transfer from one system to another. Here, we present the
+design, development and evaluation process for integrable MFH platforms, which
+extends a commercial MPI scanner with the functionality of MFH. Methods: The
+biggest issue of integrating magnetic fluid hyperthermia platforms into a
+magnetic par-ticle imaging system is the magnetic coupling of the devices,
+which induces high voltage in the imaging system, and is harming its
+components. In this paper we use a self-compensation approach derived from
+heuristic algorithms to protect the magnetic particle imaging scanner. The
+integrable platforms are evaluated regarding electrical and magnetic
+characteristics, cooling capability, field strength, the magnetic coupling to a
+replica of the magnetic particle imaging system's main solenoid and particle
+heating. Results: The MFH platforms generate suitable magnetic fields for
+magnetic heating of particles and are compatible with a commercial magnetic
+particle imaging scanner. In combination with the imaging system, selective
+heating with a gradient field and steerable heating positioning using the MPI
+focus fields are possible. Conclusion: The proposed MFH platforms serve as a
+therapeutic tool to unlock MFH functionality of a commercial magnetic particle
+imaging scanner, enabling its use in future preclinical trials of MPI-guided,
+spatially selective magnetic hyperthermia therapy.",2309.12186v1
+2002-05-15,Magnetic Fluctuations with a Zero Mean Field in a Random Fluid Flow with a Finite Correlation Time and a Small Magnetic Diffusion,"Magnetic fluctuations with a zero mean field in a random flow with a finite
+correlation time and a small yet finite magnetic diffusion are studied.
+Equation for the second-order correlation function of a magnetic field is
+derived. This equation comprises spatial derivatives of high orders due to a
+non-local nature of magnetic field transport in a random velocity field with a
+finite correlation time. For a random Gaussian velocity field with a small
+correlation time the equation for the second-order correlation function of the
+magnetic field is a third-order partial differential equation. For this
+velocity field and a small magnetic diffusion with large magnetic Prandtl
+numbers the growth rate of the second moment of magnetic field is estimated.
+The finite correlation time of a turbulent velocity field causes an increase of
+the growth rate of magnetic fluctuations. It is demonstrated that the results
+obtained for the cases of a small yet finite magnetic diffusion and a zero
+magnetic diffusion are different. Astrophysical applications of the obtained
+results are discussed.",0205233v1
+2005-06-30,Magnetic versus nonmagnetic doping effects on the magnetic ordering in the Haldane chain compound PbNi2V2O8,"A study of an impurity driven phase-transition into a magnetically ordered
+state in the spin-liquid Haldane chain compound PbNi2V2O8 is presented. Both,
+macroscopic magnetization as well as 51V nuclear magnetic resonance (NMR)
+measurements reveal that the spin nature of dopants has a crucial role in
+determining the stability of the induced long-range magnetic order. In the case
+of nonmagnetic (Mg2+) doping on Ni2+ spin sites (S=1) a metamagnetic transition
+is observed in relatively low magnetic fields. On the other hand, the magnetic
+order in magnetically (Co2+) doped compounds survives at much higher magnetic
+fields and temperatures, which is attributed to a significant anisotropic
+impurity-host magnetic interaction. The NMR measurements confirm the predicted
+staggered nature of impurity-liberated spin degrees of freedom, which are
+responsible for the magnetic ordering. In addition, differences in the
+broadening of the NMR spectra and the increase of nuclear spin-lattice
+relaxation in doped samples, indicate a diverse nature of electron spin
+correlations in magnetically and nonmagnetically doped samples, which begin
+developing at rather high temperatures with respect to the antiferromagnetic
+phase transition.",0506808v1
+2006-09-15,Superconducting pipes and levitating magnets,"Motivated by a beautiful demonstration of the Faraday's and Lenz's law in
+which a small neodymium magnet falls slowly through a conducting
+non-ferromagnetic tube, we consider the dynamics of a magnet falling through a
+superconducting pipe. Unlike the case of normal conducting pipes, in which the
+magnet quickly reaches the terminal velocity, inside a superconducting tube the
+magnet falls freely. On the other hand, to enter the pipe the magnet must
+overcome a large electromagnetic energy barrier. For sufficiently strong
+magnets, the barrier is so large that the magnet will not be able to penetrate
+it and will be suspended over the front edge. We calculate the work that must
+done to force the magnet to enter a superconducting tube. The calculations show
+that superconducting pipes are very efficient at screening magnetic fields. For
+example, the magnetic field of a dipole at the center of a short pipe of radius
+$a$ and length $L \approx a$ decays, in the axial direction, with a
+characteristic length $\xi \approx 0.26 a$. The efficient screening of the
+magnetic field might be useful for shielding highly sensitive superconducting
+quantum interference devices, SQUIDs. Finally, the motion of the magnet through
+a superconducting pipe is compared and contrasted to the flow of ions through a
+trans-membrane channel.",0609141v1
+2007-02-18,Planar Atom Trap and Magnetic Resonance 'Lens' Designs,"We present various planar magnetic designs that create points above the plane
+where the magnitude of the static magnetic field is a local minimum. Structures
+with these properties are of interest in the disciplines of neutral atom
+confinement, magnetic levitation, and magnetic resonance imaging. Each planar
+permanent magnet design is accompanied by the equivalent planar single
+non-crossing conductor design. Presented designs fall into three categories
+producing: a) zero value magnetic field magnitude point minima, b) non-zero
+magnetic field magnitude point minima requiring external bias magnetic field,
+and c) self-biased non-zero magnetic field magnitude point minima. We also
+introduce the Principle of Amperean Current Doubling in planar perpendicularly
+magnetized thin films that can be used to improve the performance of each
+permanent magnet design we present. Single conductor current-carrying designs
+are suitable for single layer lithographic fabrication, as we experimentally
+demonstrate. Finally, we present the case that nanometer scale recording of
+perpendicular anisotropy thin magnetic films using presently available data
+storage technology can provide the ultimate miniaturization of the presented
+designs.",0702154v1
+2008-05-26,Magnetic field induced incommensurate resonance in cuprate superconductors,"The influence of a uniform external magnetic field on the dynamical spin
+response of cuprate superconductors in the superconducting state is studied
+based on the kinetic energy driven superconducting mechanism. It is shown that
+the magnetic scattering around low and intermediate energies is dramatically
+changed with a modest external magnetic field. With increasing the external
+magnetic field, although the incommensurate magnetic scattering from both low
+and high energies is rather robust, the commensurate magnetic resonance
+scattering peak is broadened. The part of the spin excitation dispersion seems
+to be an hourglass-like dispersion, which breaks down at the heavily low energy
+regime. The theory also predicts that the commensurate resonance scattering at
+zero external magnetic field is induced into the incommensurate resonance
+scattering by applying an external magnetic field large enough.",0805.3922v2
+2010-10-22,Dissipation in dynamos at low and high magnetic Prandtl numbers,"Using simulations of helically driven turbulence, it is shown that the ratio
+of kinetic to magnetic energy dissipation scales with the magnetic Prandtl
+number in power law fashion with an exponent of approximately 0.6. Over six
+orders of magnitude in the magnetic Prandtl number the magnetic field is found
+to be sustained by large-scale dynamo action of alpha-squared type. This work
+extends a similar finding for small magnetic Prandtl numbers to the regime of
+large magnetic Prandtl numbers. At large magnetic Prandtl numbers, most of the
+energy is dissipated viscously, lowering thus the amount of magnetic energy
+dissipation, which means that simulations can be performed at magnetic Reynolds
+numbers that are large compared to the usual limits imposed by a given
+resolution. This is analogous to an earlier finding that at small magnetic
+Prandtl numbers, most of the energy is dissipated resistively, lowering the
+amount of kinetic energy dissipation, so simulations can then be performed at
+much larger fluid Reynolds numbers than otherwise. The decrease in magnetic
+energy dissipation at large magnetic Prandtl numbers is discussed in the
+context of underluminous accretion found in some quasars.",1010.4805v2
+2011-07-08,Antimagnets: Controlling magnetic fields with superconductor-metamaterial hybrids,"Magnetism is very important in science and technology, from magnetic
+recording to energy generation to trapping cold atoms. Physicists have managed
+to master magnetism - to create and manipulate magnetic fields- almost at will.
+Surprisingly, there is at least one property which until now has been elusive:
+how to 'switch off' the magnetic interaction of a magnetic material with
+existing magnetic fields without modifying them. Here we introduce the
+antimagnet, a design to conceal the magnetic response of a given volume from
+its exterior, without altering the external magnetic fields, somehow analogous
+to the recent theoretical proposals for cloaking electromagnetic waves with
+metamaterials. However, different from these devices requiring extreme material
+properties, our device is feasible and needs only two kinds of available
+materials: superconductors and isotropic magnetic materials. Antimagnets may
+have applications in magnetic-based medical techniques such as MRI or in
+reducing the magnetic signature of vessels or planes.",1107.1647v1
+2012-06-29,Enhancement of critical current density in superconducting/magnetic multi-layers with slow magnetic relaxation dynamics and large magnetic susceptibility,"We propose to use superconductor-magnet multi-layer structure to achieve high
+critical current density by invoking polaronic mechanism of pinning. The
+magnetic layers should have large magnetic susceptibility to enhance the
+coupling between vortices and magnetization in magnetic layers. The relaxation
+of the magnetization should be slow. When the velocity of vortices is low, they
+are dressed by nonuniform magnetization and move as polarons. In this case, the
+viscosity of vortices proportional to the magnetic relaxation time is enhanced
+significantly. As velocity increases, the polarons dissociate and the viscosity
+drops to the usual Bardeen-Stephen one, resulting in a jump in the I-V curve.
+Experimentally the jump shows up as a depinning transition and the
+corresponding current at the jump is the depinning current. For Nb and proper
+magnet multi-layer structure, we estimate the critical current density $J_c\sim
+10^{9}\ \rm{A/m^2}$ at magnetic field $B\approx 1$ T.",1206.6929v2
+2013-03-07,Complex Magnetic Phase Diagram of a Geometrically Frustrated Sm Lattice: SmPd2Al3 case,"Magnetism in SmPd2Al3 was investigated on a single crystal by magnetometry
+and neutron diffraction. SmPd2Al3 represents a distinctive example of the Sm
+magnetism exhibiting complex magnetic behavior at low temperatures with four
+consecutive magnetic phase transitions at 3.4, 3.9, 4.3 and 12.5 K. The rich
+magnetic phase diagram of this compound reflects the specific features of the
+Sm3+ ion, namely the energy nearness of the ground-state multiplet J = 5/2 and
+the first excited multiplet J = 7/2 in conjunction with strong crystal field
+influence. Consequently, a significantly reduced Sm magnetic moment in
+comparison with the theoretical Sm3+ free-ion value is observed. Despite the
+strong neutron absorption by natural samarium and the small Sm magnetic moment
+(~ 0.2 {\mu}B) we have successfully determined the magnetic k-vector (1/3, 1/3,
+0) of the phase existing in the temperature interval 12.5 - 4.3 K. This
+observation classifies the SmPd2Al3 compound as a magnetically frustrated
+system. The complex magnetic behavior of this material is further illustrated
+by kinetic effects of the magnetization inducing rather complicated magnetic
+structure with various metastable states.",1303.1607v1
+2013-05-20,Magnetization of neutron star matter,"The magnetization of neutron star matter in magnetic fields is studied by
+employing the FSUGold interaction. It is found that the magnetic
+susceptibilities of the charged particles (proton, electron and muon) can be
+larger than that of neutron. The effects of the anomalous magnetic moments
+(AMM) of each component on the magnetic susceptibility are examined in detail.
+It is found that the proton and electron AMM affect their respective magnetic
+susceptibility evidently in strong magnetic fields. In addition, they are the
+protons instead of the electrons that contribute most significantly to the
+magnetization of the neutron star matter in a relative weak magnetic field, and
+the induced magnetic field due to the magnetization can be appear to be very
+large. Finally, the effect of the density-dependent symmetry energy on the
+magnetization is discussed.",1305.4533v1
+2014-09-29,Review and comparison of magnet designs for magnetic refrigeration,"One of the key issues in magnetic refrigeration is generating the magnetic
+field that the magnetocaloric material must be subjected to. The magnet
+constitutes a major part of the expense of a complete magnetic refrigeration
+system and a large effort should therefore be invested in improving the magnet
+design. A detailed analysis of the efficiency of different published permanent
+magnet designs used in magnetic refrigeration applications is presented in this
+paper. Each design is analyzed based on the generated magnetic flux density,
+the volume of the region where this flux is generated and the amount of magnet
+material used. This is done by characterizing each design by a figure of merit
+magnet design efficiency parameter, $\Lambda_\mathrm{cool}$. The designs are
+then compared and the best design found. Finally recommendations for designing
+the ideal magnet design are presented based on the analysis of the reviewed
+designs.",1409.8046v1
+2015-04-22,Magnetized stars with differential rotation and a differential toroidal field,"We have succeeded in obtaining magnetized equilibrium states with
+differential rotation and differential toroidal magnetic fields. If an internal
+toroidal field of a proto-neutron star is wound up from the initial poloidal
+magnetic field by differential rotation, the distribution of the toroidal
+magnetic field is determined by the profile of this differential rotation.
+However, the distributions of the toroidal fields in all previous magnetized
+equilibrium studies do not represent the magnetic winding by the differential
+rotation of the star. In this paper, we investigate a formulation of a
+differential toroidal magnetic field that represents the magnetic field wound
+up by differential rotation. We have developed two functional forms of
+differential toroidal fields which correspond to a v-constant and a j-constant
+field in analogy to differential rotations. As the degree of the differential
+becomes very high, the toroidal magnetic field becomes highly localized and
+concentrated near the rotational axis. Such a differential toroidal magnetic
+field would suppress the low-T/|W| instability more efficiently even if the
+total magnetic field energy is much smaller than that of a non-differential
+toroidal magnetic field.",1504.05961v2
+2016-04-01,Photoinduced Magnetic Nanoprobe Excited by Azimuthally Polarized Vector Beam,"The concept of magnetic nanoprobes (or magnetic nanoantennas) providing a
+magnetic near-field enhancement and vanishing electric field is presented and
+investigated, together with their excitation. It is established that a
+particular type of cylindrical vector beams called azimuthally electric
+polarized vector beams yield strong longitudinal magnetic field on the beam
+axis where the electric field is ideally null. These beams with an electric
+polarization vortex and cylindrical symmetry are important in generating high
+magnetic to electric field contrast, i.e., large local field admittance, and in
+allowing selective excitation of magnetic transitions in matter located on the
+beam axis. We demonstrate that azimuthally polarized vector beam excitation of
+a photoinduced magnetic nanoprobe made of a magnetically polarizable nano
+cluster leads to enhanced magnetic near field with resolution beyond
+diffraction limit. We introduce two figures of merit as magnetic field
+enhancement and local field admittance normalized to that of a plane wave that
+are useful to classify magnetic nanoprobes and their excitation. The
+performance of magnetic nanoprobe and azimuthal polarized beams is quantified
+in comparison to other illumination options and with several defect scenarios.",1604.00379v1
+2016-09-23,Chirality-driven orbital magnetic moments as a new probe for topological magnetic structures,"When electrons are driven through unconventional magnetic structures, such as
+skyrmions, they experience emergent electromagnetic fields that originate
+several Hall effects. Independently, ground state emergent magnetic fields can
+also lead to orbital magnetism, even without the spin-orbit interaction. The
+close parallel between the geometric theories of the Hall effects and of the
+orbital magnetization raises the question: does a skyrmion display topological
+orbital magnetism? Here we first address the smallest systems with nonvanishing
+emergent magnetic field, trimers, characterizing the orbital magnetic
+properties from first-principles. Armed with this understanding, we study the
+orbital magnetism of skyrmions, and demonstrate that the contribution driven by
+the emergent magnetic field is topological. This means that the topological
+contribution to the orbital moment does not change under continous deformations
+of the magnetic structure. Furthermore, we use it to propose a new experimental
+protocol for the identification of topological magnetic structures, by soft
+x-ray spectroscopy.",1609.07529v1
+2017-02-24,Angle-dependence and optimal design for magnetic bubblecade with maximum speed,"Unidirectional magnetic domain-wall motion is a key concept underlying
+next-generation application devices. Such motion has been recently demonstrated
+by applying an alternating magnetic field, resulting in the coherent
+unidirectional motion of magnetic bubbles. Here we report the optimal
+configuration of applied magnetic field for the magnetic bubblecade, the
+coherent unidirectional motion of magnetic bubbles, driven by a tilted
+alternating magnetic field. The tilted alternating magnetic field induces
+asymmetric expansion and shrinkage of the magnetic bubbles under the influence
+of the Dzyaloshinskii-Moriya interaction, resulting in continuous shift of the
+bubbles in time. By realizing the magnetic bubblecade in PtCoPt films, we find
+that the bubblecade speed is sensitive to the tilt angle with a maximum at an
+angle, which can be explained well by a simple analytical form within the
+context of the domain-wall creep theory. A simplified analytic formula for the
+angle for maximum speed is then given as a function of the amplitude of the
+alternating magnetic field. The present observation provides a practical design
+rule for memory and logic devices based on the magnetic bubblecade.",1702.07439v1
+2014-03-11,Piezo-Voltage Manipulation of the Magnetization and Magnetic Reversal in Thin Fe Film,"We carefully investigated the in-plane magnetic reversal and corresponding
+magnetic domain structures in Fe/GaAs/piezo-transducer heterostructure using
+longitudinal magneto-optical Kerr microscopy. The coexistence of the <100>
+cubic magnetic anisotropy and uniaxial magnetic anisotropy was observed in our
+Fe thin film grown on GaAs. The induced deformation along [110] orientation can
+effectively manipulate the magnetic reversal with magnetic field applied along
+magnetic uniaxial hard [110] axes. The control of two-jump magnetization
+switching to one-jump magnetization switching during the magnetic reversal was
+achieved by piezo-voltages with magnetic field applied in [100] direction. The
+additional uniaxial anisotropy induced by piezo-voltages at -75 /75V are
+-1.400/1400 J/m3 .",1403.2469v1
+2018-09-13,On the role of magnetic fields in star formation,"Magnetic fields are observed in star forming regions. However simulations of
+the late stages of star formation that do not include magnetic fields provide a
+good fit to the properties of young stars including the initial mass function
+(IMF) and the multiplicity. We argue here that the simulations that do include
+magnetic fields are unable to capture the correct physics, in particular the
+high value of the magnetic Prandtl number, and the low value of the magnetic
+diffusivity. The artificially high (numerical and uncontrolled) magnetic
+diffusivity leads to a large magnetic flux pervading the star forming region.
+We argue further that in reality the dynamics of high magnetic Prandtl number
+turbulence may lead to local regions of magnetic energy dissipation through
+reconnection, meaning that the regions of molecular clouds which are forming
+stars might be essentially free of magnetic fields. Thus the simulations that
+ignore magnetic fields on the scales on which the properties of stellar masses,
+stellar multiplicities and planet-forming discs are determined, may be closer
+to reality than those which include magnetic fields, but can only do so in an
+unrealistic parameter regime.",1809.04921v1
+2020-04-24,Observation of magnetic domains in uniaxial magnets via small-angle electron diffraction and Foucault imaging,"Observation of magnetic domains is important in understanding the magnetic
+properties of magnetic materials and devices. In this study, we report that the
+magnetic domains of M-type hexaferrites with uniaxial anisotropy can be
+visualized via small-angle electron diffraction and Foucault imaging. The
+position of the diffraction pattern spots has the same period as that of
+magnetic domains in a Sc-substituted hexaferrite
+(BaFe$_{12-x-\delta}$Sc$_x$Mg$_\delta$O$_{19}$). Conversely, the spots were
+observed four times longer than the period of magnetic domains in hexaferrite
+without substitution (BaFe$_{12}$O$_{19}$), demonstrating the long-range order
+of the Bloch walls. When the specimen was tilted, the magnetic deflection
+effect, as well as the periodic spots of magnetic domains, occurred. Thus, we
+were able to visualize the magnetic domains with different magnetization
+directions and domain orientations by selecting deflection spots. The results
+indicate that the technique utilized in this study is useful in observing the
+magnetic materials with uniaxial anisotropy.",2004.11589v1
+2021-01-12,Modeling of Thermal Magnetic Fluctuations in Nanoparticle Enhanced Magnetic Resonance Detection,"We present a systematic numerical modeling investigation of magnetization
+dynamics and thermal magnetic moment fluctuations of single magnetic domain
+nanoparticles in a configuration applicable to enhancing inductive magnetic
+resonance detection signal to noise ratio (SNR). Previous proposals for
+oriented anisotropic single magnetic domain nanoparticle amplification of
+magnetic flux in MRI coil focused only on the coil pick-up voltage signal
+enhancement. Here we extend the analysis to the numerical evaluation of the SNR
+by modeling the inherent thermal magnetic noise introduced into the detection
+coil by the insertion of such anisotropic nanoparticle-filled coil core. We
+utilize the Landau-Lifshitz-Gilbert equation under the Stoner-Wohlfarth single
+magnetic domain (macrospin) assumption to simulate the magnetization dynamics
+in such nanoparticles due to AC drive field as well as thermal noise. These
+simulations are used to evaluate the nanoparticle configurations and shape
+effects on enhancing SNR. Finally, we explore the effect of narrow band
+filtering of the broadband magnetic moment thermal fluctuation noise on the
+SNR. Our results provide the impetus for relatively simple modifications to
+existing MRI systems for achieving enhanced detection SNR in scanners with
+modest polarizing magnetic fields.",2101.04649v1
+2019-03-28,Micromagnetics of rare-earth efficient permanent magnets,"The development of permanent magnets containing less or no rare-earth
+elements is linked to profound knowledge of the coercivity mechanism.
+Prerequisites for a promising permanent magnet material are a high spontaneous
+magnetization and a sufficiently high magnetic anisotropy. In addition to the
+intrinsic magnetic properties the microstructure of the magnet plays a
+significant role in establishing coercivity. The influence of the
+microstructure on coercivity, remanence, and energy density product can be
+understood by {using} micromagnetic simulations. With advances in computer
+hardware and numerical methods, hysteresis curves of magnets can be computed
+quickly so that the simulations can readily provide guidance for the
+development of permanent magnets. The potential of rare-earth reduced and free
+permanent magnets is investigated using micromagnetic simulations. The results
+show excellent hard magnetic properties can be achieved in grain boundary
+engineered NdFeB, rare-earth magnets with a ThMn12 structure, Co-based
+nano-wires, and L10-FeNi provided that the magnet's microstructure is
+optimized.",1903.11922v1
+2021-04-27,Mechanism of parametric pumping of magnetization precession in a nanomagnet. Parametric mechanism of current-induced magnetization reversal,"A mechanism of current-induced magnetization reversal based on the parametric
+resonance is described. The source of the magnetization reversal is a
+current-induced magnetic field, which is applied perpendicularly to the easy
+axis of magnetic anisotropy of a ferromagnetic nanomagnet. The current-induced
+magnetic field was measured in a FeCoB nanomagnet to be 60 Gauss at a current
+density of 65 mA/um2. Two mechanisms of the magnetization reversal are
+described and calculated. The first mechanism is the reversal by a RF
+electrical current, which modulated at a frequency close to the precession
+frequency of the nanomagnet. The second mechanism is the reversal by a DC
+electrical current, in which the magneto-resistance and the current dependency
+of the induced magnetic field create a positive feedback loop, which amplifies
+a random tiny thermal fluctuation into a large magnetization precession leading
+to the magnetization reversal. The combination of the proposed mechanism with
+conventional magnetization-reversal mechanisms such as the Spin Torque and the
+Spin-Orbit Torque can improve the performance of a Magnetic Random Access
+Memory.",2104.13008v1
+2021-05-02,Magnetic textures in a hexaferrite thin film and their response to magnetic fields revealed by phase microscopy,"We investigated magnetic textures in a Sc-doped hexaferrite film by means of
+phase microscopy (PM) with a hole-free phase plate in a transmission electron
+microscope. In a zero magnetic field, the stripe-shaped magnetic domains
+coexist with magnetic bubbles. The magnetization in both magnetic domains was
+oriented perpendicular to the film and the domain walls have an in-plane
+magnetization. In the remnant state at 9.2 mT, several magnetic bubbles were
+formed with the formation of stripe-shaped magnetic domains, and the
+out-of-plane component in the stripe-shaped domains gradually appeared as the
+film thickness increased. As the film thickness increases further, the magnetic
+bubbles with clockwise or counter-clockwise spin helicities formed a triangular
+lattice. These results in the remnant state suggest that the domain wall energy
+in the magnetic bubble domains is lower in the thicker region.",2105.00396v1
+2022-04-20,Control of magnetic susceptibility of probiotic strain Lactobacillus Rhamnosus GG,"The paper investigates the increase in the natural magnetically controlled
+properties of probiotic microorganisms Lactobacillus rhamnosus GG (LGG) and
+their ability to form magnetic sensitive inclusions (MsI). The magnetic
+susceptibility of LGG was increased by modifying the nutrient medium
+composition and by cultivating the probiotic culture in a constant magnetic
+field. Therefore, this study can be useful for their further use as
+magnetically controlled vectors, since it is being extensively researched for
+the use in targeted drug delivery in cancer treatment, for the prevention of
+chemotherapy complications, etc. The results of this study indicate that
+growing microorganisms with natural magnetically-guided properties in a
+modified medium with iron chelate and in an external magnetic field leads to an
+increase in the magnetic susceptibility of LGG by 1,8 and 2,6 times,
+respectively, compared with the control. The best magnetic susceptibility was
+recorded for LGG suspensions, which were grown in a constant magnetic field and
+cultured in modified medium with iron chelate. The LGG suspension, grown both
+in a constant magnetic field and on a modified medium with iron chelate, had
+the highest magnetic susceptibility and was 4.8 times larger than the control.",2204.09338v1
+2022-09-22,Stacking and Layer dependence of magnetic properties in Ti\textsubscript{2}C and Fe\textsubscript{2}C,"Magnetic MXenes are turning out to be an important family of materials for
+exploring 2D magnetism. However, investigations into the inter-dependence of
+layer thickness, stacking patterns and magnetism in these materials, from a
+microscopic point of view, is still lacking. In this work, we have used Density
+Functional Theory (DFT) based calculations to understand the effects of layer
+thickness and stacking on the magnetic properties in two magnetic MXenes,
+Ti$_{2}$C and Fe$_{2}$C in their monolayer and bilayer forms. The ground state
+magnetic structures, magnetic moments, magnetic exchange interactions, magnetic
+transition temperatures and magnetic anisotropy energies are calculated and
+analysed using their electronic structures and standardised models. We find
+that in both systems increase in layer thickness (monolayer to bilayer) affects
+the ground state magnetic configuration which is driven by the changes in the
+magnetic exchange interactions. While the effects of stacking pattern is rather
+weak in Ti$_{2}$C, they are substantial, both qualitatively and quantitatively
+in Fe$_{2}$C. The computed results are analysed from their electronic
+structures. The results suggest that fascinating physical effects can be
+obtained in Fe$_{2}$C by tuning the layer thickness and stacking patterns,
+making it more suitable for device applications.",2209.10765v1
+2023-01-04,Magnetic light amplification by stimulated emission of radiation in subwavelength systems of a dielectric cavity and magnetic quantum emitters,"We propose a magnetic laser in a subwavelength system consisting of a
+high-refractive-index dielectric cavity and an active medium formed by magnetic
+quantum emitters. Stimulated emissions of magnetic quantum emitters induced by
+their coherent interactions with quantized magnetic fields of a cavity are
+theoretically considered. The condition to archive such a magnetic laser is
+obtained. Numerical results show that magnetic lasers are feasible in some
+realistic systems, for example, a silicon disk of high-quality whispering
+gallery modes with embedded emitters. Furthermore, the competitions between the
+electric interaction and magnetic one in terms of their Purcell factors are
+also considered in some magnetic laser achievable systems. In a
+wavelength-scale silicon block of a high-order magnetic mode, the ratio of
+magnetic Purcell factor to the electric one can reach more than ~10^3 large.
+Our results open up ways to enhanced magnetic light-matter interactions.",2301.01418v2
+2023-04-23,Magnetism and Fermiology of Kagome Magnet YMn6Sn4Ge2,"Kagome lattice magnets are an interesting class of materials as they can host
+topological properties in their magnetic and electronic structures. YMn6Sn6 is
+one such compound in which a series of competing magnetic phases is stabilized
+by an applied magnetic field, and both an enigmatic topological Hall effect and
+a Dirac crossing close to the Fermi energy have been realized. This material
+also shows a magnetization-induced Lifshitz transition and evidence of a unique
+charge spin coupling in one of the magnetic phases, namely the fan-like phase.
+Tuning the magnetism, and thus the interplay with the electronic states, opens
+new avenues for precise control of these novel properties. Here, we demonstrate
+the extreme sensitivity of the magnetic phases in YMn6Sn4Ge2 through the
+investigation of structural, magnetic, and transport properties. The high
+sensitivity to small doping provides great potential for engineering the
+magnetic phases and associated electronic properties in this family of
+rare-earth kagome magnets.",2304.11502v1
+2023-06-02,Accelerating the electronic-structure calculation of magnetic systems by equivariant neural networks,"Complex spin-spin interactions in magnets can often lead to magnetic
+superlattices with complex local magnetic arrangements, and many of the
+magnetic superlattices have been found to possess non-trivial topological
+electronic properties. Due to the huge size and complex magnetic moment
+arrangement of the magnetic superlattices, it is a great challenge to perform a
+direct DFT calculation on them. In this work, an equivariant deep learning
+framework is designed to accelerate the electronic calculation of magnetic
+systems by exploiting both the equivariant constraints of the magnetic
+Hamiltonian matrix and the physical rules of spin-spin interactions. This
+framework can bypass the costly self-consistent iterations and build a direct
+mapping from a magnetic configuration to the ab initio Hamiltonian matrix.
+After training on the magnets with random magnetic configurations, our model
+achieved high accuracy on the test structures outside the training set, such as
+spin spiral and non-collinear antiferromagnetic configurations. The trained
+model is also used to predict the energy bands of a skyrmion configuration of
+NiBrI containing thousands of atoms, showing the high efficiency of our model
+on large magnetic superlattices.",2306.01558v1
+2023-08-10,Change ratios of magnetic helicity and magnetic free energy during major solar flares,"Magnetic helicity is an important concept in solar physics, with a number of
+theoretical statements pointing out the important role of magnetic helicity in
+solar flares and coronal mass ejections (CMEs). Here we construct a sample of
+47 solar flares, which contains 18 no-CME-associated confined flares and 29
+CME-associated eruptive flares. We calculate the change ratios of magnetic
+helicity and magnetic free energy before and after these 47 flares. Our
+calculations show that the change ratios of magnetic helicity and magnetic free
+energy show distinct different distributions in confined flares and eruptive
+flares. The median value of the change ratios of magnetic helicity in confined
+flares is $-0.8$%, while this number is $-14.5$% for eruptive flares. For the
+magnetic free energy, the median value of the change ratios is $-4.3$% for
+confined flares, whereas this number is $-14.6$% for eruptive flares. This
+statistical result, using observational data, is well consistent with the
+theoretical understandings that magnetic helicity is approximately conserved in
+the magnetic reconnection, as shown by confined flares, and the CMEs take away
+magnetic helicity from the corona, as shown by eruptive flares.",2308.05366v1
+1997-01-30,Light Element Abundances From z=0 To z=5,"Plausible ratios of deuterium to hydrogen D/H as a function of metallicity,
+time, and redshift are investigated. Guided by the heavy element abundance
+patterns observed locally in Galactic dwarf stars and at large redshift in
+quasi-stellar object absorption line systems, empirical evolution of the
+relative abundance ratios Li/D, B/D, N/D, O/D, and F/D for QSO absorption line
+systems are given for the possible evolutionary patterns in D/H. Shortened
+abstract.",9701243v1
+2005-03-04,Solid state components of varying compositions in the outflow of the Red Rectangle,"We present high resolution Spitzer spectroscopy of several pointings in the
+outflow of the Red Rectangle. Besides the resonances due to the C-rich PAHs,
+the spectra show a wealth of new emission bands, in particular in the 13-19.5
+micron range. We argue that these bands are due to solid state components, and
+show that simple oxides of a varying composition show a good match to the data.
+The presence of these O-rich species in the supposedly C-rich outflow is
+unexplained.",0503101v1
+1995-11-22,Influence of surfactants on the structure of titanium oxide gels : experiments and simulations,"We report here on experimental and numerical studies of the influence of
+surfactants on mineral gel synthesis. The modification of the gel structure
+when the ratios water-precursor and water-surfactant vary is brought to the
+fore by fractal dimension measures. A property of {\em polydispersity of the
+initial hydrolysis} is proposed to explain these results, and is successfuly
+tested through numerical experiments of three dimensional chemically limited
+aggregation.",9511002v1
+1994-02-10,Critical Properties of the Mott Transition in the Hubbard Model,"We introduce a systematic low-energy approach to strongly correlated electron
+systems in infinite dimensions, and apply it to the problem of the
+correlation-induced metal-insulator transition in the half-filled Hubbard
+model. We determine the low-energy scaling functions of the metallic state,
+including the single-particle Green function and dynamical spin susceptibility,
+as well as thermodynamic properties and relate them to experimental data in
+transition metal oxides.",9402047v1
+1994-03-01,Berezinskii-Kosterlitz-Thouless Transition in Spin-Charge Separated Superconductor,"A model for spin-charge separated superconductivity in two dimensions is
+introduced where the phases of the spinon and holon order parameters couple
+gauge-invariantly to a statistical gauge-field representing chiral
+spin-fluctuations. The model is analyzed in the continuum limit and in the
+low-temperature limit. In both cases we find that physical electronic phase
+correlations show a superconducting-normal phase transition of the
+Berezinskii-Kosterlitz-Thouless type, while statistical gauge-field excitations
+are found to be strictly gapless. The normal-to-superconductor phase boundary
+for this model is also obtained as a function of carrier density, where we find
+that its shape compares favorably with that of the experimentally observed
+phase diagram for the oxide superconductors.",9403003v1
+1994-07-01,Charge Transfer Excitons and the Metal-Insulator Transition in the High Temperature Superconductors,"The effects of the nearest neighbour Coulomb repulsion, V, are considered in
+the one dimensional copper-oxide chain using the modified Lanczos method. Above
+a critical value of V we find that charge transfer excitons are the lowest
+lying energy exitations in the insulating phase. Close to the metal-insulator
+transition and $V=0$ there is good `particle-hole' symmetry, showing that the
+mapping from a two band model to a one band model is appropriate. The effect of
+the nearest neighbour repulsion is to create states in the gap and to pin the
+Fermi level upon hole doping.",9407004v1
+1994-08-31,Observable Zero Sound in Strongly Correlated Metals,"The slow zero-sound mode expected near the Mott transition in strongly
+interacting two-dimensional Fermi systems that are neutral is shown to persist
+as the physical sound mode in the case that the fermion carries electronic
+charge and is embedded in a positive ionic background. The latter sound
+velocity softens completely precisely at the Mott transition, indicating that a
+zone-center structural transition will occur in the system. We suggest that
+this phonon-softening mechanism is related to the structural transitions
+commonly observed in the oxide superconductors.",9408096v1
+1994-08-31,Liberating Exotic Slaves,"The introduction of confined, ``slave'' fields is frequently useful as a
+formal device in models of condensed matter physics; it becomes a conceptual
+necessity for describing possible phases of matter where the slaves are
+liberated. Here I discuss some aspects of the fractional quantum Hall effect
+from this point of view, emphasizing analogies with phenomena in other areas of
+physics, particularly to the Meissner and Higgs mechanisms, and to
+confinement-deconfinement transitions. In this application, and in some recent
+attempts to model the normal state of copper oxide superconductors, it is
+important to employ slave anyon fields.",9408100v1
+1994-11-11,Many-body and Covalence Effects in the Polarization of Ferroelectric Perovskites,"The ferroelectric polarization of perovskite oxides is much larger than
+implied by displacement of static ionic charges. We use an explicitly
+correlated scheme to investigate the phenomenon; charge transport is evaluated
+as a geometric quantum phase. Both covalence and electron-electron interaction
+enhance polarization in the weakly correlated regime. At higher values of the
+electron-electron interaction, the system undergoes a transition from a band
+insulator to a Mott insulator: the static ionic charge is continuous across the
+transition, whereas the polarization is discontinuous. Above the transition,
+oxygen transports a positive charge.",9411050v1
+1995-05-16,Umklapp scattering from spin fluctuations in Copper-Oxides,"The $\mathbf k$-dependent electronic momentum relaxation rate due to Umklapp
+scattering from antiferromagnetic spin fluctuations is studied within a
+renormalized mean-field approach to an extended $t-J$ model appropriate to
+YBa$_2$Cu$_3$O$_{7-x}$ and other cuprates. Transport coefficients are
+calculated in a relaxation time approximation. We compare these results with
+those obtained with the phenomenological assumption that all scattering
+processes dissipate momentum. We show that the latter, which violates momentum
+conservation, leads to quite different magnitudes and temperature dependences
+of resistivities and Hall coefficients.",9505067v2
+1995-08-11,Superfluid anisotropy in YBCO: Evidence for pair tunneling superconductivity,"Proximity effect and pair tunneling models are applied as alternative
+scenarios to explain the recently measured $ab$-plane and $c$-axis components
+of the superfluid tensor in Copper-Oxide superconductors which contain chains,
+such as $YBa_2Cu_3O_{6.95}$. It is argued that conventional proximity effect
+models, which couple chains and planes via single electron tunneling only, are
+incompatible with the experimental observations. On the other hand several
+surprising features of the experimental data are readily explained by the
+presence of a microscopic pair tunneling process.",9508043v1
+1995-08-14,Interlayer tunneling in a non-Fermi-liquid metal,"We study the effect of interlayer tunneling in the gauge theory describing a
+quasi-two-dimensional paramagnetic metal close to a second-order or weakly
+first-order antiferromagnetic phase boundary. In that theory, two species of
+fermions have opposite (rather than equal) charges with respect to the gauge
+field. We find that single-particle interlayer tunneling is suppressed at low
+energies. The effect of pair tunneling is analyzed within the $(3-d)$
+expansion. The resulting phase diagram has superconducting and non-Fermi-liquid
+normal phases, and so is compatible with that of the copper-oxide
+superconductors.",9508050v1
+1996-05-03,Finite-temperature Fermi-edge singularity in tunneling studied using random telegraph signals,"We show that random telegraph signals in metal-oxide-silicon transistors at
+millikelvin temperatures provide a powerful means of investigating tunneling
+between a two-dimensional electron gas and a single defect state. The tunneling
+rate shows a peak when the defect level lines up with the Fermi energy, in
+excellent agreement with theory of the Fermi-edge singularity at finite
+temperature. This theory also indicates that defect levels are the origin of
+the dissipative two-state systems observed previously in similar devices.",9605020v1
+1996-05-30,Coupling to optical phonons in the one-dimensional t-J model: Effects on superconducting fluctuations and phase separation,"The one-dimensional (1D) $t$-$J$ Holstein model is studied by exact
+diagonalization of finite rings using a variational approximation for the
+phonon states. Due to renormalization effects induced by the phonons, for
+intermediate electron-phonon coupling, the phase separation (PS) boundary, and
+with it the region of dominating superconducting fluctuations is shifted
+substantially to smaller values of $J/t$ as compared to the pure $t$-$J$ model.
+Superconducting correlations are weakened through charge density wave
+interactions mediated by the phonons. Possible consequences for the high $T_c$
+oxides are discussed.",9605190v1
+1996-06-06,Aspects of the normal state phase of copper oxide planes in high Tc superconductors,"We examine various aspects of the normal state phase of ${\rm CuO_{2}}$
+planes in the high Tc superconductors. In particular, within the context of the
+three band Hubbard model, we study as a function of doping the competition
+between a charge density wave phase induced by oxygen breathing modes,
+antiferromagnetic order and paramagnetism. To account for the strong electronic
+interactions, we use the finite $U$ slave boson method of Kotliar and
+Ruckenstein.",9606032v1
+1996-09-25,Spectral functions in doped transition metal oxides,"We present experimental photoemission and inverse photoemission spectra of
+SrTiO$_{3- \delta}$ representing electron doped $d^0$ systems. Photoemission
+spectra in presence of electron doping exhibit prominent features arising from
+electron correlation effects, while the inverse photoemssion spectra are
+dominated by spectral features explainable within single-particle approaches.
+We show that such a spectral evolution in chemically doped correlated systems
+is not compatible with expectations based on Hubbard or any other similar
+model. We present a new theoretical approach taking into account the
+inhomogeneity of the `real' system which gives qualitatively different results
+compared to standard `homogeneous' models and is in quantitative agreement with
+experiments.",9609259v1
+1997-02-12,Charge stripes and spin correlations in copper-oxide superconductors,"Recent neutron diffraction studies have yielded evidence that, in a
+particular cuprate family, holes doped into the CuO(2) planes segregate into
+stripes that separate antiferromagnetic domains. Here it is shown that such a
+picture provides a quantitatively consistent interpretation of the spin
+fluctuations measured by neutron scattering in La(1.85)Sr(0.15)CuO(4) and
+YBa(2)Cu(3)O(6+x).",9702117v1
+1997-02-21,Local moment formation in zinc doped cuprates,"We suggest that when zinc is substituted for copper in the copper oxide
+planes of high $T_{c}$ superconductors, it does not necessarily have a valency
+of 2+. Rather, the valency of a zinc impurity should be determined by its
+surrounding medium. In order to study this hypothesis, we examine the effect of
+static impurities inducing diagonal disorder within a one band Hubbard model
+coupled to a localised state. We use this model to discuss the physics of zinc
+doping in the cuprates. Specifically, we discuss the formation of local moments
+near impurity sites and the modification of the transverse spin susceptibility
+in the antiferromagnetic state.",9702190v1
+1997-03-14,Theory of colossal magnetoresistance,"The history and recent developments in studying (colossal) magnetoresistance
+in perovskite manganese oxides is reviewed. We emphasize the growing evidence
+for strongly coupled spin, charge and lattice degrees of freedom. Together with
+disorder, these provide the microscopic driving forces for local and
+inhomogeneous textures. The modeling and experimental probes for localized
+charge-spin-lattice (polaron) structures, and their multiscale ordering, is
+discussed in terms of a growing synergy of solid state physics and materials
+science perspectives.",9703148v1
+1997-06-03,Nanoscale Field-Effect Transistors: An Ultimate Size Analysis,"We have used a simple, analytically solvable model to analyze the
+characteristic s of dual-gate metal-oxide-semiconductor field-effect
+transistors (MOSFETs) with 10-nm-scale channel length L. The model assumes
+ballistic dynamics of 2D electrons in an undoped channel between highly doped
+source and drain. When applied to silicon n-MOSFETs, calculations show that the
+voltage gain (necessary for logic applications) drops sharply at L ~ 10 nm,
+while the conductance modulation remains sufficient for memory applications
+until L ~ 4 nm.",9706026v2
+1997-07-31,Fingering Instability in Combustion,"A thin solid (e.g., paper), burning against an oxidizing wind, develops a
+fingering instability with two decoupled length scales. The spacing between
+fingers is determined by the P\'eclet number (ratio between advection and
+diffusion). The finger width is determined by the degree two dimensionality.
+Dense fingers develop by recurrent tip splitting. The effect is observed when
+vertical mass transport (due to gravity) is suppressed. The experimental
+results quantitatively verify a model based on diffusion limited transport.",9707333v1
+1997-09-29,Modulated spin and charge densities in cuprate superconductors,"Neutron scattering experiments have played a crucial role in characterizing
+the spin and charge correlations in copper-oxide superconductors. While the
+data are often interpreted with respect to specific theories of the cuprates,
+an attempt is made here to distinguish those facts that can be extracted
+empirically, and the connections that can be made with minimal assumptions.",9709325v1
+1997-10-08,Spin and orbital excitation spectrum in the Kugel-Khomskii model,"We discuss spin and orbital ordering in the twofold orbital degenerate
+superexchange model in three dimensions relevant to perovskite transition metal
+oxides. We focus on the particular point on the classical phase diagram where
+orbital degeneracy is lifted by quantum effects exclusively. Dispersion and
+damping of the spin and orbital excitations are calculated at this point taking
+into account their mutual interaction. Interaction corrections to the
+mean-field order parameters are found to be small. We conclude that
+quasi-one-dimensional Neel spin order accompanied by the uniform
+d_{3z^2-r^2}-type orbital ordering is stable against quantum fluctuations.",9710070v1
+1998-04-15,Phase Diagram of High-T_c Superconductors from a Field Theory Model,"The renormalization group approach to correlated fermions is used to
+determine the phase diagram of the oxide cuprates modeled by the t-t' Hubbard
+model at the Van Hove filling. Spin-dependent interactions give rise to
+instabilities corresponding to ferromagnetic, antiferromagnetic and d-wave
+superconducting phases. Antiferromagnetism and d-wave superconductivity arise
+from the same interactions, and compete in the same region of parameter space.",9804153v1
+1998-06-26,Quantitative Determination of a Microscopic Mechanism of High Tc Superconductivity,"Within the t-J model of copper-oxides, the condensation energy can be related
+to the change in the dynamical spin structure factor between the
+superconducting and the normal states. By analyzing previous experimental data,
+we show that the change associated with the resonant neutron scattering peak
+found in $YBa_2Cu_3O_7$ can quantitatively account for the condensation energy.
+We argue that this analysis suggests a microscopic mechanism for high Tc
+superconductivity.",9806336v2
+1998-09-18,On the glass transition temperature in covalent glasses,"We give a simple demonstration of the formula relating the glass transition
+temperature, $T_g$, to the molar concentration $x$ of a modifier in two types
+of glasses: binary glasses, whose composition can be denoted by
+$X_nY_m+xM_pY_q$, with ^$X$ an element of III-rd or IV-th group (e.g. B, or Si,
+Ge), while $M_pY_q$ is an alkali oxide or chalcogenide; next, the network
+glasses of the type $A_xB_{1-x}$, e.g. $Ge_xSe_{1-x}$, $Si_xTe_{1-x}$, etc.
+After comparison, this formula gives an exact expression of the parameter
+$\beta$ of the modified Gibbs-Di Marzio equation.",9809245v1
+1998-11-19,The Singlet-Triplet Pseudo-Jahn-Teller Centers in Copper Oxides,"One of the most exciting features of the hole centers CuO_{4}^{5-} in doped
+cuprates is an unusually complicated ground state which is the result of the
+electronic quasi-degeneracy. An additional hole, doped to the basic
+CuO_{4}^{6-} cluster with the b_{1g} hole can occupy both the same hybrid
+Cu3d-O2p orbital state resulting in a Zhang-Rice singlet ^1A_{1g} and the
+purely oxygen e_u molecular orbital resulting in a singlet or triplet ^{1,3}E_u
+term with the close energies. We present detailed analysis of the
+(pseudo)-Jahn-Teller effect driven by the near-degeneracy within the
+(^1A_{1g},^{1,3}E_u)-manifold.",9811293v1
+1999-01-03,"Comment on ""Theory of metal-insulator transitions in gated semiconductors"" (B. L. Altshuler and D. L. Maslov, Phys. Rev. Lett. 82, 145 (1999))","In a recent Letter, Altshuler and Maslov propose a model which attributes the
+anomalous temperature and field dependence of the resistivity of
+two-dimensional electron (or hole) systems to the charging and discharging of
+traps in the oxide (spacer), rather than to intrinsic behavior of interacting
+particles associated with a conductor-insulator transition in two dimensions.
+We argue against this model based on existing experimental evidence.",9901005v1
+1999-02-09,Andreev reflections in the pseudogap state of cuprate supercondcutors,"We propose that, if the pseudogap state in the cuprate superconductors can be
+described in terms of the phase-incoherent preformed pairs, there should exist
+Andreev reflection from these pairs even above the superconducting transition
+temperature, $T_c$. After giving qualitative arguments for this effect, we
+present more quantitative calculations based on the Bogoliubov--de Gennes
+equation. Experimental observations of the effects of Andreev reflections above
+$T_c$---such as an enhanced tunneling conductance below the gap along the
+copper oxide plane---could provide unambiguous evidence for the preformed pairs
+in the pseudogap state.",9902125v2
+1999-02-12,Optical Conductivity in a Simple Model of Pseudogap State in Two-Dimensional System,"We present calculation of optical conductivity in a simple model of
+electronic spectrum of two-dimensional system with ""hot patches"" on the Fermi
+surface, leading to non Fermi-liquid renormalization of the spectral density
+(pseudogap) on these patches. It is shown that this model qualitatively
+reproduces basic anomalies of optical experiments in the pseudogap state of
+copper oxides.",9902192v1
+1999-06-01,"Interplay between orbital ordering and lattice distortions in LaMnO3, YVO3, and YTiO3","We have studied the interplay between orbital ordering, Jahn-Teller and
+GdFeO3-type lattice distortions in perovskite-type transition-metal oxides
+using model Hartree-Fock calculations. It has been found that the covalency
+between A-site cations and oxygens causes interaction between the Jahn-Teller
+and GdFeO3-type distortions. The present calculations explain why the d-type
+Jahn-Teller distortion and orbital ordering compatible with it are realized in
+LaMnO3, YVO3 and YTiO3",9906010v1
+1999-06-15,Internal Spatiotemporal Stochastic Resonance in a Microscopic Surface Reaction Model,"We show the existence of internal stochastic resonance in a microscopic
+stochastic model for the oscillating CO oxidation on single crystal surfaces.
+This stochastic resonance arises directly from the elementary reaction steps of
+the system without any external input. The lattice gas model is investigated by
+means of Monte Carlo simulations. It shows oscillation phenomena and mesoscopic
+pattern formation. Stochastic resonance arises once homogeneous nucleation in
+the individual surface phases (reconstructed and non-reconstructed) is added.
+This nucleation is modelled as a noise process. As a result, synchronization of
+the kinetic oscillations is obtained. Internal stochastic resonance may thus be
+an internal regulation mechanism of extreme adaptability.",9906215v1
+1999-07-02,Quantum Phase Fluctuations in High Tc Superconductors,"If phase coherence determines the superconducting transition temperature Tc
+in the cuprate oxides, it is of great interest to understand the role that
+dynamics of the phase fluctuation plays in bringing about depletion of the
+superconducting condensate. We will show that a phase correlation function can
+be calculated that allows us to describe depletion of superconducting
+condensate as a result of the quantum fluctuation. In two dimension, dynamic
+phase fluctuation or pair fluctuation gives rise to a condensate depletion
+linear with temperature as T$\to O$ in superconductors with nodes at the fermi
+surface.",9907035v2
+1999-07-15,Stripe phases in high-temperature superconductors,"Stripe phases are predicted and observed to occur in a class of
+strongly-correlated materials describable as doped antiferromagnets, of which
+the copper-oxide superconductors are the most prominent representative. The
+existence of stripe correlations necessitates the development of new principles
+for describing charge transport, and especially superconductivity, in these
+materials.",9907228v1
+1999-08-03,"Transport Properties in (Na,Ca)Co_2O_4 Ceramics","The resistivity and thermopower of polycrystalline (Na,Ca)Co_2O_4 were
+measured and analyzed. Both the quantities increase with x, suggesting that the
+carrier density is decreased by the substitutions of Ca^{2+} for Na^{+}.
+Considering that the temperature dependence of the resistivity show a
+characteristic change with x, the conduction mechanism is unlikely to come from
+a simple electron-phonon scattering. As a reference for NaCo_2O_4, single
+crystals of a two-dimensional Co oxide (Bi,Pb)_2M_3Co_2O_9 (M=Sr and Ba) were
+studied. The Pb substitution decreases the resistivity, leaving the thermopower
+nearly intact.",9908039v1
+1999-08-18,Inelastic neutron scattering peak in Zn substituted YBa2Cu3O7,"The effects of nonmagnetic impurities on the neutron scattering intensity are
+studied for a model of the copper oxide layers in the normal state. The
+contribution to the Q=(pi,pi) neutron scattering intensity from processes
+involving the scattering of the spin fluctuations from an impurity with large
+momentum transfers are calculated within the random phase approximation. It is
+shown that this type of scatterings could lead to a peak in the neutron
+scattering intensity in the normal state.",9908266v1
+1999-09-01,Normal Fermi Liquid Behavior of Quasiholes in the Spin-Polaron Model for Copper Oxides,"Based on the t-J model and the self-consistent Born approximation, the
+damping of quasiparticle hole states near the Fermi surface is calculated in a
+low doping regime. Renormalization of spin-wave excitations due to hole doping
+is taken into account. The damping is shown to be described by a familiar form
+$\text{Im}\Sigma({\bf k}^{\prime},\epsilon)\propto (\epsilon^{2}/
+\epsilon_{F})\ln(\epsilon/ \epsilon_{F})$ characteristic of the 2-dimensional
+Fermi liquid, in contrast with the earlier statement reported by Li and Gong
+[Phys. Rev. B {\bf 51}, 6343 (1995)] on the marginal Fermi liquid behavior of
+quasiholes.",9909020v1
+1999-09-22,Dielectric Response Near the Density-Driven Mott Transition in infinite dimensions,"We study the dielectric response of correlated systems which undergo a Mott
+transition as a function of band filling within the dynamical mean field
+framework. We compute the dielectric figure of merit (DFOM), which is a measure
+of dielectric efficiency and an important number for potential device
+applications. It is suggested how the DFOM can be optimized in real transition
+metal oxides. The structures seen in the computed Faraday rotation are
+explained on the basis of the underlying local spectral density of the
+$d=\infty$ Hubbard model.",9909326v1
+1999-10-20,Proposal for an Experiment to Test a Theory of High Temperature Superconductors,"A theory for the phenomena observed in Copper-Oxide based high temperature
+superconducting materials derives an elusive time-reversal and rotational
+symmetry breaking order parameter for the observed pseudogap phase ending at a
+quantum-critical point near the composition for the highest $T_c$. An
+experiment is proposed to observe such a symmetry breaking. It is shown that
+Angle-resolved Photoemission yields a current density which is different for
+left and right circularly polarized photons. The magnitude of the effect and
+its momentum dependence is estimated. Barring the presence of domains of the
+predicted phase an asymmetry of about 0.1 is predicted at low temperatures in
+moderately underdoped samples.",9910310v1
+1999-11-09,The Mott transition in V_2 O_3 and Ni Se_x S_{2-x}: insights from dynamical mean field theory,"We discuss some aspects of the pressure (or interaction) driven Mott
+transition, in three dimensional transition metal oxides by means of dynami cal
+mean field theory. We isolate the universal properties of the transition from
+the aspects which depend more on the detailed chemistry of the compounds. In
+this light we can understand the main differences and the remarkable
+similarities between these systems. Both theory and experiment converge on the
+transfer of spectral weight from low energies to high energies as the universal
+mechanism underlying the Mott transition, and we comment on the possible
+relevance of these ideas to other metal to non metal transitions.",9911114v1
+1999-11-15,Selection Rules for Resonant Inelastic X-Ray Scattering from Tetragonal Copper-Oxides,"We demonstrate the utility of point group representation theory for symmetry
+analysis in resonant inelastic x-ray scattering. From its
+polarization-dependence, we show that a 5 eV inelastic feature in Sr2CuO2Cl2
+has pure B1g symmetry and assign it to a transition in the cell-perturbation
+calculations of Simon, et. al. [Phys. Rev. B., 54, R3780 (1996)]. We discuss
+how Raman selection rules are broken at nonzero momentum transfer and how this
+can also act as a probe of wave function symmetry.",9911215v1
+1999-11-16,Topological Scenario for Stripe Formation in Manganese Oxides,"The spin-charge-orbital complex structures of manganites are studied using
+topological concepts. The key quantity is the ""winding number"" w associated
+with the Berry-phase connection of an e_g electron parallel-transported through
+Jahn-Teller centers, along zigzag one-dimensional paths in an antiferromagnetic
+environment of t_{2g} spins. From these concepts, it is shown that the
+""bi-stripe"" and ""Wigner-crystal"" states observed experimentally have different
+w's. Predictions for the spin structure of the charge-ordered states for
+heavily doped manganites are discussed.",9911248v1
+1999-11-30,From antiferromagnetism to d-wave superconductivity in the 2D t-J model,"We have found that the two dimensional t-J model, for the physical parameter
+range J/t = 0.4 reproduces the main experimental qualitative features of
+High-Tc copper oxide superconductors: d-wave superconducting correlations are
+strongly enhanced upon small doping and clear evidence of off diagonal long
+range order is found at the optimal doping \delta ~ 0.15. On the other hand
+antiferromagnetic long range order, clearly present at zero hole doping, is
+suppressed at small hole density with clear absence of antiferromagnetism at
+\delta >~ 0.1.",9911478v1
+1999-12-20,A planar diagram approach to the correlation problem,"We transpose an idea of 't Hooft from its context of Yang and Mills' theory
+of strongly interacting quarks to that of strongly correlated electrons in
+transition metal oxides and show that a Hubbard model of N interacting electron
+species reduces, to leading orders in N, to a sum of almost planar diagrams.
+The resulting generating functional and integral equations are very similar to
+those of the FLEX approximation of Bickers and Scalapino. This adds the Hubbard
+model at large N to the list of solvable models of strongly correlated
+electrons.
+  PACS Numbers: 71.27.+a 71.10.-w 71.10.Fd",9912350v1
+2000-01-04,Doppler shift on local density of states and local impurity scattering in the vortex state,"The vortex state thermal and transport properties of the high T_c copper
+oxides can be understood in a d-wave gap model and are dominated by the
+extended quasiparticle states that exist along the nodal directions in momentum
+space. The Doppler shift on these states due to the circulating supercurrents
+around the vortex core, introduces new van Hove ridges into the energy
+dependent local density of states (LDOS) as a function of distance in the
+region between cores. We emphasize the topology of these ridges and the effect
+on them of local impurity scattering in Born and unitary limit. We treat
+possible orthorhombicity. Effective local scttering rates are also obtaines.",0001029v1
+2000-01-27,s+d pairing in orthorhombic phase of copper-oxides,"A microscopical theory of electronic spectrum and superconductivity is
+formulated within the two-dimensional anisotropic t-J model with t_{x}\neq
+t_{y} and J_{x}\neq J_{y}. Renormalization of electronic spectrum and
+superconductivity mediated by spin-fluctuations are investigated within the
+Eliashberg equation in the weak coupling approximation. The gap function has
+d+s symmetry with the extended s-wave component being proportional to the
+asymmetry t_{y} - t_{x}. Some experimental consequences of the obtained results
+are discussed.",0001401v1
+2000-01-31,Universal c-axis conductivity of high-$T_c$ oxides in the superconducting state,"The anisotropy in the temperature dependence of the in-plane and c-axis
+conductivities of high-T_c cuprates in the superconducting state is shown to be
+consistent with a strong in-plane momentum dependence of both the quasiparticle
+scattering rate and the interlayer hopping integral. Applying the cold spot
+scattering model recently proposed by Ioffe and Millis (Phys. Rev. B {\bf 58},
+11631 (1998)) to the superconducting state, we find that the c-axis
+conductivity varies approximately as T^3 in an intermediate temperature regime,
+in good agreement with the experimental result for optimally doped
+YBa_2Cu_3O_{7-x} and Bi_2Sr_2CaCu_2O_{8+x}.",0001443v2
+2000-02-02,Charge and spin ordering in Nd{1/3}Sr{2/3}FeO{3},"We have investigated the charge and spin ordering in Nd{1/3}Sr{2/3}FeO{3}
+with neutron diffraction technique. This sample undergoes a charge ordering
+transition accompanying charge disproportionation of 2Fe4+ -> Fe3+ + Fe5+. We
+measured the superlattice reflections due to the charge and spin ordering, and
+confirmed that charges and spins order simultaneously at Tco = 185 K. The
+ordering pattern of charges and spins in this sample can be viewed as three
+dimensional stripe order, and is compared with two dimensional stripe order
+observed in other transition metal oxides.",0002023v1
+2000-02-06,Double-dot charge transport in Si single electron/hole transistors,"We studied transport through ultra-small Si quantum dot transistors
+fabricated from silicon-on-insulator wafers. At high temperatures, 4K<T<100K,
+the devices show single-electron or single-hole transport through the
+lithographically defined dot. At T<4K, current through the devices is
+characterized by multidot transport. From the analysis of the transport in
+samples with double-dot characteristics, we conclude that extra dots are formed
+inside the thermally grown gate oxide which surrounds the lithographically
+defined dot.",0002080v1
+2000-05-10,Quantum phase transition in a random-tiling model,"The analogue of a Mott-Hubbard transition is discussed, which appears at an
+incommensurate filling in a model of a two-dimensional plane, randomly tiled
+with CuO_4 `molecules', simulating the copper-oxide planes of high-T_c
+superconductors. It is shown to be a quantum phase transition, which can be
+crossed either in doping, at a fixed hopping overlap t, or in t, when the
+doping is fixed in a certain range below half-filling. It is first-order,
+closely analogous to a liquid-gas transition.",0005170v1
+2000-05-24,Difference between microscopic and effective overlaps in the copper-oxide planes of high-Tc superconductors,"We investigate parametrizations required to reproduce observed Fermi surfaces
+of overdoped and slightly underdoped LSCO in two different models. One is the
+standard three-band saddle-point slave boson (SB). The other is a model of CuO4
+`molecules' randomly tiled in the plane, emphasizing the distinction between
+the local overlap, always the full (bare) one, and the effective overlap,
+connected with the reduced bandwidth due to the random tiling (RT). We conclude
+this distinction is physically significant for underdoped, but not for
+overdoped LSCO. This is consistent with the observed open Fermi surfaces being
+due to correlation effects.",0005409v1
+2000-07-27,"Pairing, Stripes, Lattice Distortions and Superconductivity in Cuprate Oxides","We propose a model for a spatially modulated collective state of
+superconducting cuprates in which the electronic properties vary locally in
+space. In this model the regions of higher hole density (called stripes) are
+described as Luttinger liquids and the regions of lower density
+(antiferromagnetic ladders) as an interacting bosonic gas of d$_{x^2-y^2}$ hole
+pairs. We show that the transition to the superconducting state is topological
+and driven by decay processes among these elementary excitations in the
+presence of vibrations.",0007434v1
+2000-09-12,The Electrochemical Carbon Nanotube Field-Effect Transistor,"We explore the electric-field effect of carbon nanotubes (NTs) in
+electrolytes. Due to the large gate capacitance, Fermi energy shifts of order
++/- 1 V can be induced, enabling to tune NTs from p to n-type. Consequently,
+large resistance changes are measured. At zero gate voltage the NTs are hole
+doped in air with E_F ? 0.3-0.5 eV, corresponding to a doping level of ?
+10^{13} cm^{-2}. Hole-doping increases in the electrolyte. This hole doping
+(oxidation) is most likely caused by the adsorption of oxygen in air and
+cations in the electrolyte.",0009171v1
+2000-09-21,Single hole transistor in a p-Si/SiGe quantum well,"A single hole transistor is patterned in a p-Si/SiGe quantum well by applying
+voltages to nanostructured top gate electrodes. Gating is achieved by oxidizing
+the etched semiconductor surface and the mesa walls before evaporation of the
+top gates. Pronounced Coulomb blockade effects are observed at small coupling
+of the transistor island to source and drain.",0009323v2
+2000-10-13,Ab initio calculations of response properties including electron-hole interaction,"We discuss the current status of a computational approach which allows to
+evaluate the dielectric matrix, and hence electronic excitations like optical
+properties, including local field and excitonic effects. We introduce a recent
+numerical development which greatly reduces the use of memory in such type of
+calculations, and hence eliminates one of the bottlenecks for the application
+to complex systems. We present recent applications of the method, focusing our
+interest on insulating oxides.",0010194v1
+2000-10-17,Metal insulator transition in TlSr2CoO5 from orbital degeneracy and spin disproportionation,"To describe the metal insulator transition in the new oxide TlSr2CoO5 we
+investigate its electronic structure by LDA and model Hartree-Fock
+calculations. Within LDA we find a homogeneous metallic and ferromagnetic
+ground state, but when including the Coulomb interaction more explicitly within
+the Hartree-Fock approximation, we find an insulating state of lower energy
+with both spin and orbital order. We also interpret our results in terms of a
+simple model.",0010239v1
+2000-11-04,Orbital polarons and ferromagnetic insulators in manganites,"We argue that in lightly hole doped perovskite-type Mn oxides the holes
+(Mn$^{4+}$ sites) are surrounded by nearest neighbor Mn$^{3+}$ sites in which
+the occupied $3d$ orbitals have their lobes directed towards the central hole
+(Mn$^{4+}$) site and with spins coupled ferromagnetically to the central spin.
+This composite object, which can be viewed as a combined orbital-spin-lattice
+polaron, is accompanied by the breathing type (Mn$^{4+}$) and Jahn-Teller type
+(Mn$^{3+}$) local lattice distortions. We present calculations which indicate
+that for certain doping levels these orbital polarons may crystallize into a
+charge and orbitally ordered ferromagnetic insulating state.",0011070v1
+2000-11-07,Soft Phonon Anomalies in Relaxor Ferroelectrics,"A review is given of the phonon anomalies, which have been termed
+``waterfalls,'' that were recently discovered through a series of neutron
+inelastic scattering measurements on the lead-oxide relaxor systems PZN-xPT,
+PMN, and PZN. We discuss a simple coupled-mode model that has been used
+successfully to describe the basic features of the waterfall, and which relates
+this unusual feature to the presence of polar micro-regions.",0011122v1
+2000-11-13,Theory of Adsorption on Metal Substrates,"Contents:
+  5.1 Introduction
+  5.2 Concepts and definitions
+  5.3 The tight-binding picture of bonding
+  5.4 Adsorption of isolated adatoms
+  5.5 Alkali-metal adsorption: the traditional picture of on-surface adsorption
+  5.6 Substitutional adsorption and formation of surface alloys
+  5.7 Adsorption of CO on transition-metal surfaces - a model system for a
+simple molecular adsorbate
+  5.8 Co-adsorption [the example CO plus O on Ru(0001)]
+  5.9 Chemical reactions at metal surfaces
+  5.10 The catalytic oxidation of CO
+  5.11 Summary outline of main points",0011217v1
+2001-01-01,Characterization of halogen-bridged binuclear metal complexes as hybridized two-band materials,"We study the electronic structure of halogen-bridged binuclear metal (MMX)
+complexes with a two-band Peierls-Hubbard model. Based on a symmetry argument,
+various density-wave states are derived and characterized. The ground-state
+phase diagram is drawn within the Hartree-Fock approximation, while the thermal
+behavior is investigated using a quantum Monte Carlo method. All the
+calculations conclude that a typical MMX compound Pt_2(CH_3CS_2)_4I should
+indeed be regarded as a d-p-hybridized two-band material, where the oxidation
+of the halogen ions must be observed even in the ground state, whereas another
+MMX family (NH_4)_4[Pt_2(P_2O_5H_2)_4X] may be treated as single-band
+materials.",0101007v1
+2001-02-08,Heavy-Fermion Formation at the Metal-to-Insulator Transition in Gd$_{1-x}$Sr$_x$TiO$_3$,"The perovskite-like transition-metal oxide Gd$_{1-x}$Sr$_x$TiO$_3$ is
+investigated by measurements of resistivity, specific-heat, and electron
+paramagnetic resonance (EPR). Approaching the metal-to-insulator transition
+from the metallic regime ($x \geq 0.2$), the Sommerfeld coefficient $\gamma$ of
+the specific heat becomes strongly enhanced and the resistivity increases
+quadratically at low temperatures, which both are fingerprints of strong
+electronic correlations. The temperature dependence of the dynamic
+susceptibility, as determined from the Gd$^{3+}$-EPR linewidth, signals the
+importance of strong spin fluctuations, as observed in heavy-fermion compounds.",0102161v1
+2001-02-28,Nearest-neighbour Attraction Stabilizes Staggered Currents in the 2D Hubbard Model,"Using a strong-coupling approach, we show that staggered current vorticity
+does not obtain in the repulsive 2D Hubbard model for large on-site Coulomb
+interactions, as in the case of the copper oxide superconductors. This trend
+also persists even when nearest-neighbour repulsions are present. However,
+staggered flux ordering emerges {\bf only} when attractive nearest-neighbour
+Coulomb interactions are included. Such ordering opens a gap along the
+$(\pi,0)-(0,\pi)$ direction and persists over a reasonable range of doping.",0102527v3
+2001-03-08,Upper critical field in {Ba$_{1-x}$K$_x$BiO$_3$}: magnetotransport versus magnetotunneling,"Elastic tunneling is used as a powerful direct tool to determine the upper
+critical field $H_{c2}(T)$ in the high-$T_c$ oxide Ba$_{1-x}$K$_x$BiO$_3$. The
+temperature dependence of $H_{c2}$ inferred from the tunneling follows the
+Werthamer-Helfand-Hohenberg prediction for type-II superconductors. A
+comparison will be made with resistively determined critical field data.",0103183v1
+2001-04-24,Electrical current distribution across a metal-insulator-metal structure during bistable switching,"Combining scanning electron microscopy (SEM) and electron-beam-induced
+current (EBIC) imaging with transport measurements, it is shown that the
+current flowing across a two-terminal oxide-based capacitor-like structure is
+preferentially confined in areas localized at defects. As the thin-film device
+switches between two different resistance states, the distribution and
+intensity of the current paths, appearing as bright spots, change. This implies
+that switching and memory effects are mainly determined by the conducting
+properties along such paths. A model based on the storage and release of charge
+carriers within the insulator seems adequate to explain the observed memory
+effect.",0104452v1
+2001-08-01,Quantum dots in suspended single-wall carbon nanotubes,"We present a simple technique which uses a self-aligned oxide etch to suspend
+individual single-wall carbon nanotubes between metallic electrodes. This
+enables one to compare the properties of a particular nanotube before and after
+suspension, as well as to study transport in suspended tubes. As an example of
+the utility of the technique, we study quantum dots in suspended tubes, finding
+that their capacitances are reduced owing to the removal of the dielectric
+substrate.",0108020v1
+2001-08-21,"Structural compliance, misfit strain and stripe nanostructures in cuprate superconductors","Structural compliance is the ability of a crystal structure to accommodate
+variations in local atomic bond-lengths without incurring large strain
+energies. We show that the structural compliance of cuprates is relatively
+small, so that short, highly doped, Cu-O-Cu bonds in stripes are subject to a
+tensile misfit strain. We develop a model to describe the effect of misfit
+strain on charge ordering in the copper oxygen planes of oxide materials and
+illustrate some of the low energy stripe nanostructures that can result.",0108338v2
+2001-08-29,Anomalous Co-site substitution effects on the physical properties of the thermoelectric oxide NaCo2O4,"We prepared polycrystalline samples of NaCo2-xMxO4 substituted for the Co
+site by other 3d or 4d elements (M=Mn,Cu, Zn, Ru, Rh, and Pd). While some of
+the elements (M=Mn,Ru and Rh) act as a strong scatterer to give rise to a rapid
+increase in resistivity, the others (M=Cu, Zn and Pd) do not deteriorate the
+electric conduction of the host. Most unusually, the Cu substitution
+significantly enhances the thermopower, which increases the figure of merit by
+several times at 100 K.",0108485v1
+2001-09-20,Developments in the negative-U modelling of the cuprate HTSC systems,"The paper deals with the many stands that go into creating the unique and
+complex nature of the HTSC cuprates above Tc as below. Like its predecessors it
+treats charge, not spin or lattice, as prime mover, but thus taken in the
+context of the chemical bonding relevant to these copper oxides. The crucial
+shell filling, negative-U, double-loading fluctuations possible there require
+accessing at high valent local environment as prevails within the mixed valent,
+inhomogeneous two sub-system circumstance of the HTSC materials. Close
+attention is paid to the recent results from Corson, Demsar, Li, Johnson,
+Norman, Varma, Gyorffy and colleagues.",0109369v1
+2001-10-09,Evidence for three dimensional superconductivity in the cuprates oxides,"We review the empirical scenario emerging from the measured doping dependence
+of the transition temperature and the anisotropy parameter $% \gamma $ $=\xi
+_{ab}/\xi_{c}$, defined as the ratio of the correlation lengths parallel and
+perpendicular to the ab-planes. It suggests that two dimensional models cannot
+explain the occurrence of superconductivity in the cuprates. This conclusion is
+confirmed and extended in terms of a novel scaling relation. It involves the
+transition temperature, the aerial superfluid density in the ground state,
+$\gamma $ and the dynamic critical exponent of the quantum superconductor to
+insulator transition. The important implication there is that a non vanishing
+superfluid density in the ground state of the cuprates is unalterably linked to
+an anisotropic but 3D condensation mechanism.",0110173v1
+2001-10-12,What High Pressure Studies Have Taught Us about High-Temperature Superconductivity,"Superconductivity is an important area of modern research which has benefited
+enormously from experiments under high pressure conditions. The focus of this
+paper will be on three classes of high-temperature superconductors: (1) the new
+binary compound MgB2, (2) the alkali-doped fullerenes, and (3) the cuprate
+oxides. We will discuss results from experiment and theory which illustrate the
+kinds of vital information the high-pressure variable can give to help better
+understand these fascinating materials.",0110267v1
+2001-11-22,Theory for high spin systems with orbital degeneracy,"High-spin systems with orbital degeneracy are studied in the large spin
+limit. In the absence of Hund's coupling, the classical spin model is mapped
+onto disconnected orbital systems with spins up and down, respectively. The
+ground state of the isotropic model is an orbital valence bond state where each
+bond is an orbital singlet with parallel spins, and neighbouring bonds interact
+antiferromagnetically. The possible relevance to the transition metal oxides
+are discussed.",0111426v1
+2001-12-13,Dimensional cross-over and charge order in half-doped Manganites and Cobaltites,"We introduce a general model for understanding the effect of quenched
+disorder on charge ordering in half-doped Manganese- and Cobalt-Oxides with
+different crystal structures. Current experimental results (Table-1) are
+discussed in light of the global phase diagram of the model (Fig. 2).",0112240v6
+2002-01-03,Detection and Implications of a Time-reversal breaking state in underdoped Cuprates,"We present general symmetry considerations on how a Time-reversal breaking
+state may be detected by angle-resolved photoemission using circularly
+polarized photons as has been proposed earlier. Results of recent experiments
+utilizing the proposal in underdoped cuprates are analysed and found to be
+consistent in their symmetry and magnitude with a theory of the Copper-Oxides.
+These togather with evidence for a quantum critical point and marginal
+Fermi-liquid properties near optimum doping suggest that a valid microscopic
+theory of the phenomena in the cuprates has been found.",0201036v3
+2002-01-11,New Phase Transition in Polymer Solutions with Multicomponent Solvent,"Considering the density-density correlation function of a concentrated
+polymer solution with multicomponent solvent we find a phase transition due to
+the heterogeneity of excluded volume constant. This new phase transition
+implies a strong enhancement of the scattered light intensity in the critical
+region, which can explain a recent experiment showing strong light scattering
+from a ternary polymer system consisting of polyethylene oxide (PEO) dissolved
+in nitroethane and 3methyl-pentane.",0201170v2
+2002-02-08,Fermi Surface of 3d^1 Perovskite CaVO3 Near the Mott Transition,"We present a detailed de Haas van Alphen effect study of the perovskite
+CaVO3, offering an unprecedented test of electronic structure calculations in a
+3d transition metal oxide. Our experimental and calculated Fermi surfaces are
+in good agreement -- but only if we ignore large orthorhombic distortions of
+the cubic perovskite structure. Subtle discrepancies may shed light on an
+apparent conflict between the low energy properties of CaVO3, which are those
+of a simple metal, and high energy probes which reveal strong correlations that
+place CaVO3 on the verge of a metal-insulator transition.",0202147v1
+2002-02-22,Hierarchical Random Telegraph Signals in nano-junctions with Coulomb correlations,"We propose a microscopic hamiltonian together with a master equation
+description to model stochastic hierarchical Random Telegraph Signal (RTS) or
+Pop-corn noise in nano-junctions. The microscopic model incorporates the
+crucial Coulomb correlations due to the trapped charges inside the junction or
+at the metal-oxide interface. The exact solution of the microscopic model is
+based on a generalization of the Nozieres-De Dominicis method devised to treat
+the problem of the edge singularity in the X-ray absorption and emission
+spectra of metals. In the master equation description, the experimentally
+accessible transition rates are expressed in terms of the exact multi-channel
+Scattering matrix of the microscopic hamiltonian.",0202395v2
+2002-02-28,On the heavy-fermion behavior of the pyrochlore transition-metal oxide $LiV_{2}O_{4}$,"Motivated by the heavy fermion Fermi liquid (HFFL) features observed at
+low-$T$ in the pyrochlore $LiV_{2}O_{4}$, we consider a material-specific model
+that includes aspects of the local quantum chemistry, the geometrically
+frustrated lattice structure, and strong correlations in a {\it single}
+approach. In particular, we show how geometrical frustration (GF) gives rise to
+a crossover scale, $T^{*}<<J$, the intersite (AF) exchange, below which the
+metallic system shows HFFL features. Our scenario is a specific realization of
+the importance of GF effects in driving HFFL behavior in $LiV_{2}O_{4}$, and
+provides a natural understanding of various puzzling features observed
+experimentally.",0202531v1
+2002-04-16,Spatial and temporal probes in inhomogeneous systems: Theory and experiment,"The experimental and theoretical challenges posed by the study of dynamically
+inhomogeneous systems are outlined in the context of cuprates and other oxides.
+Considering the pitfalls in the single-component approach to the analysis of
+inhomogeneous systems, the effect of either temporal or spatial averaging by
+different experiments is discussed. A group-theoretical symmetry analysis of
+the observed inhomogeneities in real space and k-space observed in the cuprates
+is shown to lead to a quantitatively verifiable description of the
+inhomogeneous state, comprising of bound singlet pairs in the ground state and
+unbound fermions in the excited state. The predicted symmetry breaking
+associated with pairing is shown to be verifiable experimentally.",0204339v1
+2002-06-13,Single domain transport measurements of C60 films,"Thin films of potassium doped C60, an organic semiconductor, have been grown
+on silicon. The films were grown in ultra-high vacuum by thermal evaporation of
+C60 onto oxide-terminated silicon as well as reconstructed Si(111). The
+substrate termination had a drastic influence on the C60 growth mode which is
+directly reflected in the electrical properties of the films. Measured on the
+single domain length scale, these films revealed resistivities comparable to
+bulk single crystals. In situ electrical transport properties were correlated
+to the morphology of the film determined by scanning tunneling microscopy. The
+observed excess conductivity above the superconducting transition can be
+attributed to two-dimensional fluctuations.",0206221v1
+2002-07-10,Different routes to charge disproportionation in perovskites-type Fe oxides,"Iron perovskites CaFeO_3 and La_{0.33}Sr_{0.67}FeO_3 show charge
+disproportionation, resulting in charge-ordered states with Fe^{3+}:Fe^{5+}
+=1:1 and =2:1, respectively. We have made photoemission and unrestricted
+Hartree-Fock band-structure calculation of CaFeO_3 and compared it with
+La_{0.33}Sr_{0.67}FeO_3. With decreasing temperature, a gradual decrease of the
+spectral weight near the Fermi level occurred in CaFeO_3 as in
+La_{0.33}Sr_{0.67}FeO_3 although lattice distortion occurs only in CaFeO_3.
+Hartree-Fock calculations have indicated that both the breathing and tilting
+distortions are necessary to induce the charge disproportionation in CaFeO_3,
+while no lattice distortion is necessary for the charge disproportionation in
+La_{0.33}Sr_{0.67}FeO_3.",0207250v1
+2002-07-27,High-resolution Photoemission Study of Cd2Re2O7,"High-resolution bulk-sensitive photoemission has been measured for pyrochlore
+oxide Cd2Re2O7. Temperature variations of the spectral shapes between 20 and
+250 K are obviously observed for the Re 4f inner core and the valence band
+spectra. The Re 5d states are dominant for the DOS near the Fermi level.",0207659v1
+2002-08-28,On the Normal State Electronic properties of Layered Sr_2 RuO_4,"Based on a comprehensive perusal of experimental results, we construct a
+microscopic model describing the normal state of layered 4d oxide Sr_2 RuO_4
+incorporating relevant quantum chemical features of the material. The high-T
+anomalies are explained within a Luttinger liquid (LL) picture. Interlayer
+one-particle hopping drives a dimensional crossover to a correlated Fermi
+liquid below a scale E^{*} << t_{perp}. Using recently developed
+chain-dynamical mean field theory, the low value of E^{*}, as well as various
+puzzling features of the low-T normal state are explained as manifestations of
+the crossover from the high-T Luttinger liquid state in a consistent way.",0208559v1
+2002-08-29,Tunnel junctions on as-grown superconducting MgB2 thin films,"We demonstrate that good superconductor/insulator/normal-metal tunnel
+junctions can be fabricated on as-grown superconducting MgB2 thin films. The
+as-grown films were prepared by coevaporation at low growth temperatures of
+around 280deg. The insulating barrier was formed by an Mg overlayer, which is
+subsequently oxidized in air. The tunneling spectra for Au/MgOx/MgB2 junctions
+showed a reproducible and well-defined superconducting gap (delta= ~ 2.5 meV).
+The resultant 2delta/ kBTc was significantly smaller than the predicted BCS
+value of 3.52.",0208571v2
+2002-09-05,Orbital Kondo Effect in $CrO_{2}$: A LSDA+DMFT Study,"Motivated by a collection of experimental results indicating the strongly
+correlated nature of the ferromagnetic metallic state of $CrO_{2}$, we present
+results based on a combination of the actual bandstructure [3] with dynamical
+mean-field theory (DMFT) for the multi-orbital case. In striking contrast with
+LSDA(+U) [3] and model many-body approaches [14], much better semiquantitative
+agreement with (i) recent photoemission results, (ii) domain of applicability
+of the half-metal concept, and (iii) thermodynamic and dc transport data, is
+obtained within a single picture. Our approach has broad applications for the
+detailed first principles investigation of other transition metal oxide-based
+half-metallic ferromagnets.",0209132v1
+2002-09-12,Phase control of La2CuO4 in thin-film synthesis,"The lanthanum copper oxide, La2CuO4, which is an end member of the prototype
+high-Tc superconductors (La,Sr)2CuO4 and (La,Ba)2CuO4, crystallizes in the
+""K2NiF4"" structure in high-temperature bulk synthesis. The crystal chemistry,
+however, predicts that La2CuO4 is at the borderline of the K2NiF4 stability and
+that it can crystallize in the Nd2CuO4 structure at low synthesis temperatures.
+In this article we demonstrate that low-temperature thin-film synthesis
+actually crystallizes La2CuO4 in the Nd2CuO4 structure. We also show that the
+phase control of ""K2NiF4""-type La2CuO4 versus ""Nd2CuO4""-type La2CuO4 can be
+achieved by varying the synthesis temperature and using different substrates.",0209281v1
+2002-09-13,Coexistence of bulk antiferromagnetic order and superconductivity in the QED3 theory of copper oxides,"Within the framework of the QED3 theory of cuprates it is argued that bulk
+antiferromagnetic (AF) order can coexist with d-wave superconductivity in the
+underdoped region, in agreement with recent experiments. The AF order arises
+from the phase fluctuating d-wave superconductor via the mechanism of
+spontaneous chiral symmetry breaking, provided that fluctuations are
+sufficiently strong. The phase diagram for this coexistence is mapped out by
+means of analytical and numerical solutions of the underlying Dyson-Schwinger
+equation in the large N limit.",0209301v2
+2002-11-14,Spin Chirality Fluctuation and Anomalous Hall Effect in Itinerant Ferromagnets,"The anomalous Hall effect due to the spin chirality order and fluctuation is
+studied theoretically in a Kondo lattice model without the relativistic
+spin-orbit interaction. Even without the correlations of the localized spins,
+$\sigma_{xy}$ can emerge depending on the lattice structure and the spin
+anisotropy. We reveal the condition for this chirality-fluctuation driven
+mechanism for $\sigma_{xy}$. Our semiquantitative estimates for a pyrochlore
+oxide Nd$_2$Mo$_2$O$_7$ give a finite $\sigma_{xy} \sim 10 \Ohm^{-1} \cm^{-1}$
+together with a high resistivity $\rho_{xx} \sim 10^{-4}-10^{-3} \Ohm \cm$, in
+agreement with experiments.",0211267v1
+2002-11-28,Small polarons and c-axis transport in highly anisotropic metals,"Motivated by the anomalous c-axis transport properties of the quasi
+two-dimensional metal, $\rm Sr_2 Ru O_4$, and related compounds, we have
+studied the interlayer hopping of single electrons that are coupled strongly to
+c-axis bosons. We find a c-axis resistivity that reflects the in-plane
+electronic scattering in the low and very high temperature limits (relative to
+the characteristic temperature of the boson $T_{\rm boson}$). For temperatures
+near the $T_{\rm boson}$, a broad maximum in the resistivity can appear for
+sufficiently strong electron-boson coupling. This feature may account for the
+observed ``metallic to non-metallic crossover'' seen in these layered oxides,
+where the boson may be a phonon.",0211675v1
+2002-12-10,Quantum Phase Transition in the SU(4) Spin-Orbital Model on the Triangular Lattice,"Motivated by the absence of cooperative Jahn-Teller effect in LiNiO2 and
+BaVS3, two layered oxides with triangular planes, we study the SU(4) symmetric
+spin-orbital model on the triangular lattice. Upon reducing the next-nearest
+neighbour coupling, we show that the system undergoes a quantum phase
+transition to a liquid phase. A variational approach to this liquid phase shows
+that simple types of long-range correlations are suppressed, suggesting that it
+is stable against lattice distortions.",0212211v1
+2003-02-04,Effect of a humid environment on the surface structure of RuO2(110),"Combining density-functional theory and thermodynamics we compute the phase
+diagram of surface structures of rutile RuO2 (110) in equilibrium with water
+vapor in the complete range of experimentally accessible gas phase conditions.
+Through the formation of hydroxyl or water-like groups, already lowest
+concentrations of hydrogen in the gas phase are sufficient to stabilize an
+oxygen-rich polar oxide termination even at very low oxygen pressure.",0302075v1
+2003-02-10,Unexpected Scaling of the Performance of Carbon Nanotube Transistors,"We show that carbon nanotube transistors exhibit scaling that is
+qualitatively different than conventional transistors. The performance depends
+in an unexpected way on both the thickness and the dielectric constant of the
+gate oxide. Experimental measurements and theoretical calculations provide a
+consistent understanding of the scaling, which reflects the very different
+device physics of a Schottky barrier transistor with a quasi-one-dimensional
+channel contacting a sharp edge. A simple analytic model gives explicit scaling
+expressions for key device parameters such as subthreshold slope, turn-on
+voltage, and transconductance.",0302175v1
+2003-03-20,About possible Phonon to Magnon alignment in 2 dimensions and theory of superconductivity in Copper-Oxide planes,"We suggest that the phonon dispersion in cuprates becomes strongly
+anisotropic due to interaction with spin waves; moreover the phonon dispersion
+becomes singular along $|k_x|=|k_y|$ directions. This would allow more
+electrons to form Cooper pairs and increase temperature of the superconducting
+transition. The interaction of phonons with spin waves is more important than
+the interaction of phonons with free electrons, because spin waves do not have
+the Fermi surface constrain.",0303402v5
+2003-04-07,Comment on ``Conduction states in oxide perovskites: Three manifestations of Ti$^{3 +}$ Jahn-Teller polarons in barium titanate'',"In this comment to [S. Lenjer, O. F. Schirmer, H. Hesse, and Th. W. Kool,
+Phys. Rev. B {\bf 66}, 165106 (2002)] we discuss the electronic structure of
+oxygen vacancies in perovskites. First principles computations are in favour of
+rather deep levels in these vacancies, and Lenjer et al suggest that the
+electrons' interaction energy is negative, but data on electroconductivity are
+against.",0304160v1
+2003-04-17,Crossover between mean-field and Ising critical behavior in a lattice-gas reaction-diffusion model,"Lattice-gas models for CO oxidation can exhibit a discontinuous
+nonequilibrium transition between reactive and inactive states, which
+disappears above a critical CO-desorption rate. Using finite-size-scaling
+analysis, we demonstrate a crossover from Ising to mean-field behavior at the
+critical point, with increasing surface mobility of adsorbed CO or with
+decreasing system size. This behavior is elucidated by analogy with that of
+equilibrium Ising-type systems with long-range interactions.",0304386v1
+2003-04-30,Electronic and Structural Properties of a 4d-Perovskite: Cubic Phase of SrZrO$_3$,"First-principles density functional calculations are performed within the
+local density approximation to study the electronic properties of SrZrO$_3$, an
+insulating 4d-perovskite, in its high-temperature cubic phase, above 1400 K, as
+well as the generic 3d-perovskite SrTiO$_3$, which is also a d^0-insulator and
+cubic above 105 K, for comparison reasons. The energy bands, density of states
+and charge density distributions are obtained and a detailed comparison between
+their band structures is presented. The results are discussed also in terms of
+the existing data in the literature for both oxides.",0304703v1
+2003-06-04,"Chiral Symmetry and Collective Excitations in p-wave, d-wave and f-wave Superconductors","We discuss the origin of charge density wave (CDW) and spin density wave
+(SDW) in p-wave, d-wave and f-wave superconductors. To describe the low-energy
+quasiparticle excitation of p-wave case, we introduce a two- (one for time and
+one for space) dimensional massless Dirac model. After the non-Abelian
+bosonization is performed, the charge and spin density waves emerge from the
+model. By using this scheme, we try to explain the characteristic aspect of
+phase diagrams of various compounds, oxides and organic superconductors. The
+purpose of this paper is to make an argument that the dimensionality of the
+nodal excitation in superconductors plays an important role in the
+determination of the structure of the phase diagram.",0306095v1
+2003-06-26,Variation of Superconducting Transition Temperature in Hole-Doped Copper-Oxides,"The experimentally observed difference of superconducting critical
+temperature $T_{c}$ in hole-doped cuprates is studied by using an extended
+interlayer coupling model for layered d-wave superconductors. We show that the
+change of the maximum $T_{c}$ from series to series is determined by the next
+nearest neighboring hopping $t^{\prime}$, while the difference of the maximum
+$T_{c}$ among the compounds in a homogeneous series is controlled by the
+interlayer pairing strength. Our results provide helpful guidelines in the
+search for new high-$T_{c}$ superconductors.",0306680v1
+2003-06-27,The checkerboard modulation and the inter-layer asymmetry of the hole density in cuprates,"The 2D pair-condensate is characterized by a charge ordered state with a
+""checkerboard"" pattern in the planes and with an alternating superstructure
+along the c-axis.We find that Coulomb energy gain occurs along the c-axis,
+which is proportional to the measured condensation energy and is due to
+inter-layer charge complementarity (charge asymmetry of the boson condensate.
+The static c-axis dielectric constant and the in-plane coherence length are
+also calculated for various cuprates and compared with the available
+experimental data. We find excellent agreement .",0306698v2
+2003-06-28,Low-Temperature Quantum Critical Behaviour of Systems with Transverse Ising-like Intrinsic Dynamics,"The low-temperature properties and crossover phenomena of $d$-dimensional
+transverse Ising-like systems within the influence domain of the quantum
+critical point are investigated solving the appropriate one-loop
+renormalization group equations. The phase diagram is obtained near and at
+$d=3$ and several sets of critical exponents are determined which describe
+different responses of a system to quantum fluctuations according to the way of
+approaching the quantum critical point. The results are in remarkable agreement
+with experiments for a wide variety of compounds exhibiting a quantum phase
+transition, as the ferroelectric oxides and other displacive systems.",0306713v1
+2003-07-11,Enhanced thermoelectric properties of NaxCoO2 whisker crystals,"Single-crystalline whiskers of thermoelectric cobalt oxide, NaxCoO2, have
+been grown by an unconventional method from potassium-containing compositions,
+and their transport properties, and chemical compositions were determined. The
+growth mechanism was analyzed and interpreted by means of thermogravimetric
+analysis. At 300 K, electrical resistivity r and thermoelectric power S of the
+whisker are 102 u ohm cm and 83 uV/K, respectively. The power-factor, S2/r,
+thus is enhanced up to ~ 68 uW/K2 cm.",0307277v1
+2003-07-30,Combined atomic force microscope and electron-beam lithography used for the fabrication of variable-coupling quantum dots,"We have combined direct nanofabrication by local anodic oxidation with
+conventional electron-beam lithography to produce a parallel double quantum dot
+based on a GaAs/AlGaAs heterostructure. The combination of both nanolithography
+methods allows to fabricate robust in-plane gates and Cr/Au top gate electrodes
+on the same device for optimal controllability. This is illustrated by the
+tunability of the interdot coupling in our device. We describe our fabrication
+and alignment scheme in detail and demonstrate the tunability in
+low-temperature transport measurements.",0307743v1
+2003-08-05,Stress-aging in the electron-glass,"A new protocol for an aging experiment is studied in the electron-glass phase
+of indium-oxide films. In this protocol, the sample is exposed to a non-ohmic
+electric field F for a waiting time t_{w} during which the system attempts to
+reach a steady state (rather than relax towards equilibrium). The relaxation of
+the excess conductance dG after ohmic conditions are restored exhibit simple
+aging as long as F is not too large.",0308071v1
+2003-08-29,First-principles calculations of strontium on Si(001),"This paper reports state-of-the-art electronic structure calculations on the
+deposition of strontium on the technologically relevant, (001) orientated
+silicon surface. We identified the surface reconstructions from zero to four
+thirds monolayers and relate them to experimentally reported data. A phase
+diagram is proposed. We predict phases at 1/6, 1/4, 1/2, 2/3 and 1 monolayers.
+Our results are expected to provide valuable information in order to understand
+heteroepitaxial growth of a prominent class of high-K oxides around SrTiO3. The
+insight obtained for strontium is expected to be transferable to other alkaline
+earth metals.",0308621v1
+2003-09-01,Heteroepitaxial growth of high-K gate oxides on silicon: insights from first-principles calculations on Zr on Si(001),"Metal deposition of Zr an a Si(001) surface has been studied by
+state-of-the-art electronic structure calculations. The energy per Zr adatom as
+a function of the coverage shows, that Zr forms silicide islands even at low
+coverages. Adsorbed Zr is thermodynamically unstable against the formation of
+bulk silicide ZrSi2. The observation that the islands consist of structural
+elements of the bulk silicide is an indication that silicide grains will form
+spontaneously.",0309030v1
+2003-09-04,Mott transition and suppression of orbital fluctuations in orthorhombic 3$d^{1}$ perovskites,"Using $t_{2g}$ Wannier-functions, a low-energy Hamiltonian is derived for
+orthorhombic $3d^{1}$ transition-metal oxides. Electronic correlations are
+treated with a new implementation of dynamical mean-field theory for non-cubic
+systems. Good agreement with photoemission data is obtained. The interplay of
+correlation effects and cation covalency (GdFeO$_{3}$-type distortions) is
+found to suppress orbital fluctuations in LaTiO$_{3},$ and even more in
+YTiO$_{3}$, and to favor the transition to the insulating state.",0309102v3
+2003-09-08,Computer Modeling of Electronic Properties of Scroll-like V2O5-based Nanotubes,"Atomic models of quasi-one-dimensional 1D vanadium oxide nanostructures -
+nanotubes of various morphology (cylinder or scroll-like) formed by rolling
+(010) single layers of V2O5 are constructed and their electronic properties are
+studied using the tight-binding band theory. Compared to the cylindrical zigzag
+(n,0) and armchair (n,n)-like nanotubes, which are uniformly semi-conducting
+with the bang gap of about 2.5-2.7 eV, the band gap of the scroll-like tubes
+trends significantly to vanish (up to about 0.1 eV) depending on the atomic
+configurations of the tubes and inter-wall distances.",0309179v1
+2003-09-16,Insulator-Metal transition in the Doped 3d1 Transition Metal Oxide LaTiO3,"The doping induced insulator-metal transition in $La_{1-x}Sr_{x}TiO_{3}$ is
+studied using the ab-initio LDA+DMFT method. Combining the LDA bandstructure
+for the actual, distorted structure found recently with multi-orbital DMFT to
+treat electronic correlations, we find: $(i)$ ferro-orbital order in the Mott
+insulating state without orbital degeneracy, $(ii)$ a continuous filling
+induced transition to the paramagnetic metal (PM) with $x$, and $(iii)$
+excellent quantitative agreement with published photoemission data for the case
+of 6% doping. Our results imply that this system can be described as a
+Mott-Hubbard system without orbital (liquid) degeneracy.",0309370v1
+2003-10-03,Nanowire Growth for Sensor Arrays,"A design concept for nanowire-based sensors and arrays is described. The
+fabrication technique involves electrodeposition to directly grow nanowires
+between patterned thin film contact electrodes. To prove our concept, we have
+electrodeposited 1-mm diameter Pd single wires and small arrays. To demonstrate
+nanowire sensors, we have electrochemically grown metal (Pd, Au, Pt), metal
+oxide (Sb2O3), and conducting polymer (polyaniline) bundled nanowires. Using Pt
+bundled nanowires surface modified with glucose oxidase, we have demonstrated
+glucose detection as a demonstration of a biomolecular sensor.",0310075v1
+2003-10-15,Commensurability Transition and Stripe Phases in the Ginzburg-Landau Theory,"We phenomenologically describe the thermodynamics of charge and spin density
+waves in doped high-$T_{c}$ oxides. We have explicitly calculated stable
+non-homogeneous solutions in the incompressible spin driven stripe phase, where
+stripes are static soliton-like charge density waves (CDW), and in the vicinity
+of their critical point, where CDW's become harmonic. Our phase diagram points
+to a commensurability transition separating the low (LI) and high (HI)
+incommensurable phases. Besides, we demonstrate by rigorous group symmetry
+arguments that the stripe criticality is compatible with a second order phase
+transition.",0310364v1
+2003-10-28,Universal features of charge and spin order in a half-doped layered perovskite,"We have investigated the peculiar structure of charge and spin ordering in
+the half-doped layered perovskite oxide La$_{1.5}$Sr$_{0.5}$CoO$_4$ by elastic
+neutron scattering. Two samples with different preparation histories were
+studied. We find that the generic features of the ordered states, such as their
+short-range, glassy nature and the spin incommensurability, are
+sample-independent. At the same time, some subtle features of the ordered
+phases, such as the correlation lengths, differ.",0310662v2
+2003-11-11,First-principles study of the electrooptic effect in ferroelectric oxides,"We present a method to compute the electrooptic tensor from first principles,
+explicitly taking into account the electronic, ionic and piezoelectric
+contributions. It allows us to study the non-linear optic behavior of three
+ferroelectric ABO_3 compounds : LiNbO_3, BaTiO_3 and PbTiO_3. Our calculations
+reveal the dominant contribution of the soft mode to the electrooptic
+coefficients in LiNbO_3 and BaTiO_3 and identify the coupling between the
+electric field and the polar atomic displacements along the B-O chains as the
+origin of the large electrooptic response in these compounds.",0311240v2
+2003-11-12,Superconductivity in Na_xCoO_2yH_2O by charge fluctuation,"A new mechanism for superconductivity in the newly discovered Co-based oxide
+is proposed by using charge fluctuation. A single-band extended Hubbard model
+on the triangular lattice is studied within random phase approximation.
+$f$-wave triplet superconductivity is stabilized in the vicinity of
+charge-density-wave instability, which is in sharp contrast with the
+square-lattice case. The physical origin of the realization of the $f$-wave
+triplet state as well as the relevance to experiments are discussed.",0311266v1
+2003-12-15,Influence of the incommensurability in $Sr_{14-x}Ca_xCu_{24}O_{41}$ family compounds,"The present paper studies the influence of the structural modulation on the
+low energy physics of the $Sr_{14-x}Ca_xCu_{24}O_{41}$ oxides, using ab-initio
+determination of the on-site and nearest neighbor effective parameters. The
+structural modulations appears to be the key degree of freedom, responsible for
+the low energy properties, such as the electron localization, the formation of
+dimers in the $x=0$ compound or the anti-ferromagnetic order in the $x=13.6$
+compound.",0312369v2
+2003-12-17,In-situ epitaxial growth of superconducting La-based bilayer cuprate thin films,"We investigate the epitaxial growth of bilayer cuprate La2CaCu2O6+\delta
+using pure ozone as an oxidant, and find that even the crystal with parent
+composition without cation substitution can show metallic behavior with the aid
+of epitaxial strain effect. The hole concentration is controlled simply by
+excess-oxygen doping, and the films grown under the optimum conditions exhibit
+superconductivity below 30 K. This is the first result on the superconductivity
+of bilayer La2CaCu2O6+\delta induced purely by the excess oxygen.",0312428v1
+2003-12-18,Renormalization of resonant tunneling in MOSFETs,"We study tunneling between a localized defect state and a conduction band in
+the presence of strong electron-electron and electron-phonons interactions. We
+derive the tunneling rate as a function of the position of the defect energy
+level relative to the Fermi energy of conduction electrons. We argue that our
+results can explain the large tunneling timescales observed in experiments on
+random telegraph signals in ${\rm Si}$ metal-oxide-semiconductor field effect
+transistors.",0312503v1
+2003-12-21,"XANES spectroscopy study of Pb(Ti, Zr)O3 ferroelectric thin films","Thin films of zirconium-rich perovskites Pb1-3x/2 Lax Zr0.65 Ti0.35O3 (PLZT;
+x=0.095) were studied using X-ray absorption near-edge structure (XANES)
+spectroscopy. Is shown, that slow crystallization of the system is accompanied
+by partial reduction of lead oxides to a metal (Pb0) state. The same results
+were found in the samples of the same composition with addition of 30% mol of
+PbO. The evidence for stereo active 6s2 lone-pair is discussed.",0312559v1
+2003-12-28,"XANES Pb LIII spectra of mixed-valence compound: Minium, Pb3O4","Mixed-valence compound Pb3O4 (minium) has been studied using X-ray absorption
+near-edge structure (XANES) spectroscopy and DFT calculations. In spite of
+presence of two valence states of lead [Pb(II) and Pb(IV)], the XANES spectrum
+of studied system is corresponding to apparently unified, an intermediate
+valence state of Pb. On the other hand, the 207Pb NMR spectra definitely show
+two different spectral bands corresponding to different Pb2+ and Pb4+ ions in
+Pb3O4 crystal structure. The explanation of this contradiction is related to
+the basics of XANES and NMR spectroscopy.",0312663v1
+2004-01-29,Review on Giant Magnetoelectric effects in Oxide ferromagnetic/ferroelectric Layered Structures,"The synthesis of layered ferrite-lead titanate zirconate (PZT) and lanthanum
+nanganite-PZT and the observation of giant magneto-electric interactions are
+discussed. The ferrites used in our studies included pure and Zn substituted
+cobalt-, nickel- and lithium ferrites. Ferromagnetic manganites used included
+both calcium and strontium substituted systems. The samples were prepared from
+10-40 mm thick films obtained by tape-casting. Our studies showed strong ME
+coupling in manganite-PZT and cobalt zinc ferrite-PZT, and a giant ME effect in
+nickel zinc ferrite-PZT. We found evidence for Zn assisted enhancement in ME
+coefficients that were attributed to low anisotropy and high permeability that
+resulted in favorable magneto-mechanical coupling in the composites.",0401607v1
+2004-02-04,Quasi-Stationary Distributions for Models of Heterogeneous Catalysis,"We construct the quasi-stationary (QS) distribution for two models of
+heterogeneous catalysis having two absorbing states: the ZGB model for the
+oxidation of CO, and a version with noninstantaneous reactions. Using a
+mean-field-like approximation, we study the quasi-stationary surface coverages,
+moment ratios and the lifetime of the QS state. We also derive an improved,
+consistent one-site mean-field theory for the ZGB model.",0402132v1
+2004-02-05,Theoretical Study on Resonant Inelastic X-Ray Scattering in Quasi-One-Dimensional Cuprates,"We study theoretically the resonant inelastic x-ray scattering in
+quasi-one-dimensional insulating copper oxides, where the incident photon
+energy is tuned to the Cu1s-4p absorption energy. Our attention is focused
+particularly on the strong momentum-transfer dependence of the spectral shape
+observed in recent experiments. We describe the antiferromagnetic ground state
+within the Hartree-Fock theory, and consider charge excitations from the ground
+state within the random phase approximation. By taking account of the electron
+correlation effects perturbatively, we obtain detailed momentum-transfer
+dependence of the spectra in a semiquantitative agreement with the experiments.",0402150v1
+2004-02-19,Possible singlet to triplet pairing transition in NaxCoO2 H2O,"We present precise measurements of the upper critical field (Hc2) in the
+recently discovered cobalt oxide superconductor. We have found that the
+critical field has an unusual temperature dependence; namely, there is an
+abrupt change of the slope of Hc2(T) in a weak field regime. In order to
+explain this result we have derived and solved Gor'kov equations on a
+triangular lattice. Our experimental results may be interpreted in terms of the
+field-induced transition from singlet to triplet superconductivity.",0402503v2
+2004-03-08,Sodium Ion Ordering in NaxCoO2,"The layered sodium cobalt oxide NaxCoO2 is studied by electron diffraction
+for a wide range of sodium contents, 0.15<x<0.75. An extensive series of
+ordered Na ion-Na vacancy superlattices is found beyond the simple hexagonal
+average structure. The most strongly developed superlattice is found for the
+composition Na0.5CoO2, which displays Co3+/Co4+ charge ordering at low
+temperatures. The structural principle for some of the observed ordering
+schemes, particularly near x=0.5, is, surprisingly, the presence of lines of Na
+ions and vacancies rather than simply maximized Na-Na separations.",0403206v1
+2004-05-14,Combining high conductivity with complete optical transparency: A band-structure approach,"A comparison of the structural, optical and electronic properties of the
+recently discovered transparent conducting oxide (TCO), nanoporous Ca12Al14O33,
+with those of the conventional TCO's (such as Sc-doped CdO) indicates that this
+material belongs conceptually to a new class of transparent conductors. For
+this class of materials, we formulate criteria for the successful combination
+of high electrical conductivity with complete transparency in the visible
+range. Our analysis suggests that this set of requirements can be met for a
+group of novel materials called electrides.",0405317v1
+2004-05-16,Structural and electronic properties of MgO nanotube clusters,"Finite magnesium oxide nanotubes are investigated. Stacks of four parallel
+squares, hexagons, octagons, and decagons are constructed and studied by the
+pseudopotential density functional theory within the local-density
+approximation. Optimized structures are slightly distorted stacks of polygons.
+These clusters are insulators and the band gap of 8.5 eV is constant over an
+investigated range of the diameters of stacked polygonal rings. Using the
+L""owdin population analysis a charge transfer towards the oxygen atoms is
+estimated as 1.4, which indicates that the mixed ionocovalent bonding exists in
+investigated MgO nanotubes.",0405347v1
+2004-06-17,Superconductivity in three-layer Na0.3CoO2*1.3H2O,"The observation of superconductivity at 4.3 K in a new crystalline form of
+Na0.3CoO2*1.3H2O is reported. The new superconductor has three layers of CoO6
+octahedra per crystallographic unit cell, in contrast to the previously
+reported two-layer superconductor. The three-layer cell occurs because the
+relative orientations of neighboring CoO2 layers are distinctly different from
+what is seen in the two-layer superconducting phase. This type of structural
+difference in materials that are otherwise chemically and structurally
+identical is not possible to attain on the layered copper oxide
+superconductors. The synthesis and stability of the new phase are described.",0406409v1
+2004-06-25,Strong electron correlation effects in non-volatile electronic memory devices,"We investigate hysteresis effects in a model for non-volatile memory devices.
+Two mechanisms are found to produce hysteresis effects qualitatively similar to
+those often experimentally observed in heterostructures of transition metal
+oxides. One of them is a novel switching effect based on a metal-insulator
+transition due to strong electron correlations at the dielectric/metal
+interface. The observed resistance switching phenomenon could be the
+experimental realisation of a novel type of strongly correlated electron
+device.",0406646v1
+2004-07-04,Correlation pseudogaps in HTSC,"The electronic correlations in oxide HTSC in the normal state are analyzed by
+the generalized Hartree-Fock theory of Nambu and Gorkov. It yields two kinds of
+pseudogaps, the small pseudogap (SPG) and the large pseudogap (LPG). The first
+is obtained by the Fock integral, and the second by the Hartree integral. We
+find real gaps for the undoped materials, and pseudogaps for the doped and
+conducting ones. The latter result in the V- shaped experimental density of
+states.",0407090v1
+2004-07-12,Asymmetric Silver to Oxide Adhesion in Multilayers Deposited on Glass by Sputtering,"We have developed a wedge-loaded double-cantilever beam adhesion measurement
+set-up for thin films deposited on glass by sputtering. The test is described
+in details. Results on the Glass/sublayer/Ag/ZnO multilayer provide evidence
+that \SnOd or \TiOd perform better than ZnO as a sublayer. Then however,
+rupture within the multilayer shifts to the upper Ag/ZnO interface. The latter
+is shown to be tougher than the lower ZnO/Ag interface, an asymmetry due to
+non-equilibrium interfacial structures.",0407296v1
+2004-07-18,Directional Ordering of Fluctuations in a Two-dimensional Compass Model,"In the Mott insulating phase of the transition metal oxides, the effective
+orbital-orbital interaction is directional both in the orbital space and in the
+real space. We discuss a classical realization of directional coupling in two
+dimensions. Despite extensive degeneracy of the ground state, the model
+exhibits partial orbital ordering in the form of directional ordering of
+fluctuations at low temperatures stabilized by an entropy gap. Transition to
+the disordered phase is shown to be in the Ising universality class through
+exact mapping and multicanonical Monte Carlo simulations.",0407470v1
+2004-09-13,Pi-stacking in charged thiophene oligomers,"The pi-stacking of oxidized thiophene oligomers is investigated using
+ab-initio quantum chemistry methods. Dimers of singly-charged oligothiophenes
+are found to be unstable in the gas phase, but can be stabilized as bound
+dications in the singlet state by a polarizable solvent such as acetonitrile.
+Our calculations provide a detailed description of the mechanisms and the
+energetics involved in the dimerization phenomenon, and highlight the role and
+importance of the environment in the stabilization of the stacks. The need for
+accurate treatments of electronic correlations and of solvation effects for a
+realistic description of these materials is underscored.",0409328v1
+2004-10-05,Self-generated electronic heterogeneity and quantum glassiness in the high temperature superconductors,"We present a systematic study of the spin and charge dynamics of copper oxide
+superconductors as a function of carrier concentration $x$. Our results portray
+a coherent physical picture, which reveals a quantum critical point at optimum
+doping ($x=x_{opt}$), and the formation of an inhomogeneous glassy state at $x
+< x_{opt}$. This mechanism is argued to arise as an intrinsic property of doped
+Mott insulators, and therefore to be largely independent of material quality
+and level of disorder.",0410111v1
+2004-10-29,Raman thresholds and rigid to floppy transitions in calcium silicate glasses,"Alkaline earth silicate glasses $xCaO-(1-x)SiO_2$ exhibit a well marked
+threshold in Raman lineshapes which can be related to the onset of network
+rigidity as the concentration of calcium oxide $x$ is decreased. The present
+results are analyzed by constraint counting algorithms and more deeply
+characterized by a size increasing cluster approximation that allows to perform
+Maxwell mechanical constraint counting beyond the usual mean-field treatment.
+This permits to discuss under which structural conditions an elastic
+intermediate phase can be obtained.",0410770v1
+2004-11-09,Quantum Mott Transition and Superconductivity,"The gas-liquid transition is a first-order transition terminating at a
+finite-temperature critical point with diverging density fluctuations. Mott
+transition, a metal-insulator transition driven by Coulomb repulsion between
+electrons, has been identified with this textbook transition. However, the
+critical temperature of the Mott transition can be suppressed, resulting in
+unusual quantum criticality. It accounts for non-Fermi-liquid-like properties,
+and strongly momentum dependent quasiparticles as in many materials near the
+Mott insulator. Among all, the mode-coupling theory of the density fluctuations
+supports d-wave superconductivity at the order of a hundred Kelvin for relevant
+parameters of the copper oxide superconductors.",0411217v1
+2004-11-15,Hydration phase diagram for sodium cobalt oxide Na0.3CoO2*yH2O,"The hydration phase diagram for sodium cobalt oxyhydrate, Na0.3CoO2*yH2O
+(y=0, 0.6, 1.3), was determined as a function of relative humidity at 298K. It
+is found that greater than 75% relative humidity is needed for complete
+hydration of anhydrous Na0.3CoO2 to the superconducting phase Na0.3CoO2*1.3H2O.
+Dehydration studies show that a minimum of 43% relative humidity is needed to
+maintain the stability of the fully hydrated superconducting phase. The
+intermediate hydrate, Na0.3CoO2*0.6H2O, is stable between 10% and 50% relative
+humidity on hydration, and 35% to 0% relative humidity on dehydration.",0411387v1
+2004-11-20,Device modeling of long-channel nanotube electro-optical emitter,"We present a simple analytic model of nanotube electro-optical emitters,
+along with improved experimental measurements using PMMA-passivated devices
+with reduced hysteresis. Both the ambipolar electrical characteristics and the
+motion of the infrared-emission spot are well described. The model indicates
+that the electric field is strongly enhanced at the emission spot, and that
+device performance can be greatly improved by the use of thinner gate oxides.",0411537v2
+2005-03-01,Carbon Nanotubes as Intracellular Protein Transporters: Generality and Biological Functionality,"Various proteins adsorb spontaneously on the sidewalls of acid-oxidized
+single-walled carbon nanotubes. This simple non-specific binding scheme can be
+used to afford non-covalent protein-nanotube conjugates. The proteins are found
+to be readily transported inside various mammalian cells with nanotubes acting
+as the transporter via the endocytosis pathway. Once released from the
+endosomes, the internalized protein-nanotube conjugates can enter into the
+cytoplasm of cells and perform biological functions, evidenced by apoptosis
+induction by transported cytochrome c. Carbon nanotubes represent a new class
+of molecular transporters potentially useful for future in-vitro and in-vivo
+protein delivery applications.",0503005v1
+2005-03-07,Synthesis and Structure of the Monolayer Hydrate K03CoO2 x 04H2O,"The monolayer hydrate (MLH) K03CoO2 x 04H2O was synthesized from K06CoO2 by
+extracting K+ cations using K2S2O8 as an oxidant and the subsequent
+intercalation of water between the layers of edge-sharing CoO6 octahedra. A
+hexagonal structure (space group P63/mmc) with lattice parameters a = 2.8262(1)
+Angstrom, c = 13.8269(6) Angstrom similar to the MLH Na036CoO2 x 07H2O was
+established using high-resolution synchrotron X-ray powder diffraction data.
+The K/H2O layer in the K-MLH is disordered, which is in contrast to the Na-MLH.
+At low temperatures metallic and paramagnetic behavior was found.",0503165v1
+2005-03-21,Two Dimensional Atomic Crystals,"We report free-standing atomic crystals that are strictly 2D and can be
+viewed as individual atomic planes pulled out of bulk crystals or as unrolled
+single-wall nanotubes. By using micromechanical cleavage, we have prepared and
+studied a variety of 2D crystals, including single layers of boron nitride,
+graphite, several dichalcogenides and complex oxides. These atomically-thin
+sheets (essentially gigantic 2D molecules unprotected from the immediate
+environment) are stable under ambient conditions, exhibit high crystal quality
+and are continuous on a macroscopic scale.",0503533v1
+2005-04-05,How to detect the fourth order cumulant of electrical noise,"It is proposed to measure the current noise generated in a mesoscopic
+conductor by macroscopic quantum tunneling (MQT) in a current biased Josephson
+junction placed in parallel to the conductor. The theoretical description of
+this set-up takes into account the complete dynamics of detector and noise
+source. Explicit results are given for the specific case of current
+fluctuations in an oxide layer tunnel junction, and it is shown how the device
+allows to extract the fourth order cumulant of the noise from the MQT data for
+realistic experimental parameters.",0504120v1
+2005-04-30,Structural and Electronic Properties of the Interface between the High-k oxide LaAlO3 and Si(001),"The structural and electronic properties of the LaAlO3/Si(001) interface are
+determined using state-of-the-art electronic structure calculations. The atomic
+structure differs from previous proposals, but is reminiscent of La adsorption
+structures on silicon. A phase diagram of the interface stability is calculated
+as a function of oxygen and Al chemical potentials. We find that an
+electronically saturated interface is obtained only if dopant atoms segregate
+to the interface. These findings raise serious doubts whether LaAlO3 can be
+used as an epitaxial gate dielectric.",0505013v2
+2005-05-02,Orbital order in vanadium spinels,"Motivated by recent theoretical and experimental controversy, we present a
+theoretical study to clarify the orbital symmetry of the ground state of
+vanadium spinel oxides AV$_2$O$_4$ (A=Zn, Mg, Cd). The study is based on an
+effective Hamiltonian with spin-orbital superexchange interaction and a local
+spin-orbit coupling term. We construct a classical phase-diagram and prove the
+complex orbital nature of the ground state. Remarkably, with our new analysis
+we predict correctly also the coherent tetragonal flattening of oxygen
+octahedra. Finally, through analytical considerations as well as numerical
+ab-initio simulations, we propose how to detect the predicted complex orbital
+ordering through vanadium K edge resonant x-ray scattering.",0505031v1
+2005-05-06,Comparison of multiple-gate MOSFET architectures using Monte Carlo simulation,"Multiple-gate SOI MOSFETs with gate length equal to 25 nm are compared using
+device Monte Carlo simulation. In such architectures, the short channel effects
+may be controlled with much less stringent body and oxide thickness
+requirements than in single-gate MOSFET. Our results highlight that planar
+double-gate MOSFET is a good candidate to obtain both high current drive per
+unit-width and weak subthreshold leakage with large integration density and
+aggressive delay time, compared to non planar devices such as triple-gate or
+quadruple-gate structures.",0505168v1
+2005-05-24,Non-ohmicity and energy relaxation in diffusive 2D metals,"We analyze current-voltage characteristics taken on Au-doped indium-oxide
+films. By fitting a scaling function to the data, we extract the
+electron-phonon scattering rate as function of temperature, which yields a
+quadratic dependence of the electron-phonon scattering rate on temperature from
+1K down to 0.28K. The origin of this enhanced electron-phonon scattering rate
+is ascribed to the mechanism proposed by Sergeev and Mitin.",0505595v1
+2005-06-20,A phenomenological model of the Resonance peak in High Tc Superconductors,"A notable aspect of high-temperature superconductivity in the copper oxides
+is the unconventional nature of the underlying paired-electron states. The
+appearance of a resonance peak, observed in inelastic neutron spectroscopy in
+the superconducting state of the High Tc cuprates, its apparent linear
+correlation with the critical superconducting temperature of each of the
+compounds and its disappearance in the normal state are rather intriguing. It
+may well be that this peak is the signature of the singlet to triplet
+excitation, and is an unique characteristic of a d-wave superconductor. We
+develop a simple criterion for the resonance peak which is based on the concept
+of twist sti ness and its disappearance at T=Tc.",0506490v1
+2005-07-09,Direct Observation of Hydrogen Adsorption Sites and Nano-Cage Formation in Metal-Organic Frameworks (MOF),"The hydrogen adsorption sites in MOF5 were determined using neutron powder
+diffraction along with first-principles calculations. The metal-oxide cluster
+is primarily responsible for the adsorption while the organic linker plays only
+a secondary role. Equally important, at low temperatures and
+high-concentration, H2 molecules form unique interlinked high-symmetry
+nano-clusters with intermolecular distances as small as 3.0 Ang. and H2-uptake
+as high as 10-wt%. These results hold the key to optimizing MOF materials for
+hydrogen storage applications and also suggest that MOFs can be used as
+templates to create artificial interlinked hydrogen nano-cages with novel
+properties.",0507220v1
+2005-08-23,Direct measurement of charge transfer phenomena at ferromagnetic/superconducting oxide interfaces,"YBa2Cu3O7-x/La0.67Ca0.33MnO3 ferromagnetic/superconducting interfaces are
+analyzed by scanning transmission electron microscopy and electron energy loss
+spectroscopy with monolayer resolution. We demonstrate that extensive charge
+transfer occurs between the manganite and the superconductor, in a manner
+similar to modulation-doped semiconductors, which explains the reduced critical
+temperatures of heterostructures. This behavior is not seen with insulating
+PrBa2Cu3O7 layers. Furthermore, we confirm directly that holes in the
+YBa2Cu3O7-x are located on the CuO2 planes.",0508564v2
+2005-08-26,Role of Orbitals in the Physics of Correlated Electron Systems,"Rich properties of systems with strongly correlated electrons, such as
+transition metal oxides, is largely connected with an interplay of different
+degrees of freedom in them: charge, spin, orbital ones, as well as crystal
+lattice. Specific and often very important role is played by orbital degrees of
+freedom. In this comment I will shortly summarize the main concepts and discuss
+some of the well-known manifestations of orbital degrees of freedom, but will
+mostly concentrate on a recent development in this field.",0508631v1
+2005-09-26,Correlation between floppy to rigid transitions and non-Arrhenius conductivity in glasses,"Non-Arrhenius behaviour and fast increase of the ionic conductivity is
+observed for a number of potassium silicate glasses $(1-x)SiO_2-xK_2O$ with
+potassium oxide concentration larger than a certain value $x=x_c=0.14$.
+Recovering of Arrhenius behaviour is provided by the annealing that enhances
+densification. Conductivity furthermore obeys a percolation law with the same
+critical concentration $x_c$. These various results are the manifestation of
+the floppy or rigid nature of the network and can be analyzed with constraint
+theory. They underscore the key role played by network rigidity for the
+understanding of conduction and saturation effects in glassy electrolytes.",0509644v1
+2005-10-05,Simulation of phonon-assisted band-to-band tunneling in carbon nanotube field-effect transistors,"Electronic transport in a carbon nanotube (CNT) metal-oxide-semiconductor
+field effect transistor (MOSFET) is simulated using the non-equilibrium Green's
+functions method with the account of electron-phonon scattering. For MOSFETs,
+ambipolar conduction is explained via phonon-assisted band-to-band
+(Landau-Zener) tunneling. In comparison to the ballistic case, we show that the
+phonon scattering shifts the onset of ambipolar conduction to more positive
+gate voltage (thereby increasing the off current). It is found that the
+subthreshold swing in ambipolar conduction can be made as steep as 40mV/decade
+despite the effect of phonon scattering.",0510122v1
+2005-10-13,Electrodynamics of correlated electron matter,"Infrared spectroscopy has emerged as a premier experimental technique to
+probe enigmatic effects arising from strong correlations in solids. Here we
+report on recent advances in this area focusing on common patterns in
+correlated electron systems including transition metal oxides, intermetallics
+and organic conductors. All these materials are highly conducting substances
+but their electrodynamic response is profoundly different from the canonical
+Drude behavior observed in simple metals. These unconventional properties can
+be attributed in several cases to the formation of spin and/or charge ordered
+states, zero temperature phase transitions and strong coupling to bosonic
+modes.",0510351v1
+2005-10-31,Coexistence of double-Q spin density wave and multi-Q pair density wave in cuprate oxide superconductors,"Spatial 4a x 4a modulations, with a the lattice constant of CuO_2 planes, or
+the so called checkerboards can arise from double-Q spin density wave (SDW)
+with Q_1 = (pm pi/a, pm 3 pi/4a) and Q_2 = (pm 3 pi/4a, pm pi/a). When multi-Q
+pair density wave, that is, the condensation of d gamma-wave Cooper pairs with
+zero total momenta, pm 2Q_1, pm 2Q_2, pm 4Q_1, pm 4Q_2, and so on is induced by
+the SDW, gaps can have fine structures similar to those of the so called
+zero-temperature pseudogaps.",0510829v1
+2005-11-02,Self-aligned carbon nanotube transistors with charge transfer doping,"This letter reports a charge transfer p-doping scheme which utilizes
+one-electron oxidizing molecules to obtain stable, unipolar carbon nanotube
+transistors with a self-aligned gate structure. This doping scheme allows one
+to improve carrier injection, tune the threshold voltage Vth, and enhance the
+device performance in both the ON- and OFF- transistor states. Specifically,
+the nanotube transistor is converted from ambipolar to unipolar, the device
+drive current is increased by 2-3 orders of magnitude, the device OFF current
+is suppressed and an excellent Ion/Ioff ratio of six order of magnitude is
+obtained. The important role played by metal-nanotube contacts modification
+through charge transfer is demonstrated.",0511039v1
+2005-11-22,Fabrication of high quality ferromagnetic Josephson junctions,"We present ferromagnetic Nb/Al2O3/Ni60Cu40/Nb Josephson junctions (SIFS) with
+an ultrathin Al2O3 tunnel barrier. The junction fabrication was optimized
+regarding junction insulation and homogeneity of current transport. Using
+ion-beam-etching and anodic oxidation we defined and insulated the junction
+mesas. The additional 2 nm thin Cu layer below the ferromagnetic NiCu (SINFS)
+lowered interface roughness and ensured very homogeneous current transport. A
+high yield of junctional devices with jc spreads less than 2% was obtained.",0511546v1
+2005-12-15,Predicting polarization enhancement in multicomponent ferroelectric superlattices,"Ab initio calculations are utilized as an input to develop a simple model of
+polarization in epitaxial short-period CaTiO3/SrTiO3/BaTiO3 superlattices grown
+on a SrTiO3 substrate. The model is then combined with a genetic algorithm
+technique to optimize the arrangement of individual CaTiO3, SrTiO3 and BaTiO3
+layers in a superlattice, predicting structures with the highest possible
+polarization and a low in-plane lattice constant mismatch with the substrate.
+This modelling procedure can be applied to a wide range of layered
+perovskite-oxide nanostructures providing guidance for experimental development
+of nanoelectromechanical devices with substantially improved polar properties.",0512328v1
+2006-01-31,Crosstalk between nanotube devices: contact and channel effects,"At reduced dimensionality, Coulomb interactions play a crucial role in
+determining device properties. While such interactions within the same carbon
+nanotube have been shown to have unexpected properties, device integration and
+multi-nanotube devices require the consideration of inter-nanotube
+interactions. We present calculations of the characteristics of planar carbon
+nanotube transistors including interactions between semiconducting nanotubes
+and between semiconducting and metallic nanotubes. The results indicate that
+inter-tube interactions affect both the channel behavior and the contacts. For
+long channel devices, a separation of the order of the gate oxide thickness is
+necessary to eliminate inter-nanotube effects. Because of an exponential
+dependence of this length scale on dielectric constant, very high device
+densities are possible by using high-k dielectrics and embedded contacts.",0602006v1
+2006-02-02,Lattice polarization effects on electron-gas charge densities in ionic superlattices,"The atomic-level control achievable in artificially-structured oxide
+superlattices provides a unique opportunity to explore interface phases of
+matter including high-density 2D electron gases. Electronic-structure
+calculations show that the charge distribution of the 2D gas is strongly
+modulated by electron-phonon interactions with significant ionic polarization.
+Anharmonic finite-temperature effects must be included to reproduce experiment.
+Density functional perturbation theory is used to parameterize a simple model
+introduced to represent these effects and predict temperature dependencies.",0602045v2
+2006-02-17,Excited state spectroscopy in carbon nanotube double quantum dots,"We report on low temperature measurements in a fully tunable carbon nanotube
+double quantum dot. A new fabrication technique has been used for the top-gates
+in order to avoid covering the whole nanotube with an oxide layer as in
+previous experiments. The top-gates allow us to form single dots, control the
+coupling between them and we observe four-fold shell filling. We perform
+inelastic transport spectroscopy via the excited states in the double quantum
+dot, a necessary step towards the implementation of new microwave-based
+experiments.",0602424v1
+2006-02-24,Crystal-field states in NaCoO2 and in wet cobalt superconductors (NaxCoO2),"We claim that for calculations of the electronic structure of 3d oxides very
+strong electron correlations have to be taken into account similarly to those
+assumed in many-electron crystal field approach. For Co3+ ions in NaxCoO2.yH2O
+there are 15 low lying many-electron states within 0.1 eV as can be obtained in
+the many-electron CEF approach with taking into account the spin-orbit
+coupling. We claim, that the used by us Hamiltonian for the trigonal distortion
+is correct.",0602592v1
+2006-02-27,"Origin of the large thermoelectric power in oxygen-variable RBaCo_{2}O_{5+x} (R=Gd, Nd)","Thermoelectric properties of GdBaCo_{2}O_{5+x} and NdBaCo_{2}O_{5+x} single
+crystals have been studied upon continuous doping of CoO_2 planes with either
+electrons or holes. The thermoelectric response and the resistivity behavior
+reveal a hopping character of the transport in both compounds, providing the
+basis for understanding the recently found remarkable divergence of the Seebeck
+coefficient at x=0.5. The doping dependence of the thermoelectric power evinces
+that the configurational entropy of charge carriers, enhanced by their spin and
+orbital degeneracy, plays a key role in the origin of the large thermoelectric
+response in these correlated oxides.",0602618v1
+2006-03-03,Electrostatic Modulation of the Superfluid Density in a Ultrathin La2-xSrxCuO4 Film,"By capacitively charging an underdoped ultrathin La2-xSrxCuO4 film with an
+electric field applied across a gate insulator with a high dielectric constant,
+relative changes of the areal superfluid density n_{s\Box}$ of unprecedented
+strength were observed in measurements of the film kinetic inductance. Although
+$n_{s\Box}$ appears to be substantially reduced by disorder, the data provide,
+for the first time on the same sample, direct compelling evidence for the
+Uemura relation $T_{c} \propto n_{s\Box}(T=0)$ in the underdoped regime of
+copper-oxide superconductors.",0603076v2
+2006-03-13,Charge Transfer Induced Polarity Switching in Carbon Nanotube Transistors,"We probed the charge transfer interaction between the amine-containing
+molecules: hydrazine, polyaniline and aminobutyl phosphonic acid, and carbon
+nanotube field effect transistors (CNTFETs). We successfully converted p-type
+CNTFETs to n-type and drastically improved the device performance in both the
+ON- and OFF- transistor states utilizing hydrazine as dopant. We effectively
+switched the transistor polarity between p- and n- type by accessing different
+oxidation states of polyaniline. We also demonstrated the flexibility of
+modulating the threshold voltage (Vth) of a CNTFET by engineering various
+charge-accepting and -donating groups in the same molecule.",0603322v1
+2006-04-05,Growth mode control of the free carrier density in SrTiO3-d films,"We have studied the growth dynamics and electronic properties of SrTiO3-d
+homoepitaxial films by pulsed laser deposition. We find the two dominant
+factors determining the growth mode are the kinetics of surface crystallization
+and oxidation. When matched, persistent two-dimensional layer-by-layer growth
+can be obtained for hundreds of unit cells. By tuning these kinetic factors,
+oxygen vacancies can be frozen in the film, allowing controlled, systematic
+doping across a metal-insulator transition. Metallic films can be grown,
+exhibiting Hall mobilities as high as 25,000 cm2/Vs.",0604117v1
+2006-04-24,Potential Profiling of the Nanometer-Scale Charge Depletion Layer in n-ZnO/p-NiO Junction Using Photoemission Spectroscopy,"We have performed a depth-profile analysis of an all-oxide p-n junction diode
+n-ZnO/p-NiO using photoemission spectroscopy combined with Ar-ion sputtering.
+Systematic core-level shifts were observed during the gradual removal of the
+ZnO overlayer, and were interpreted using a simple model based on charge
+conservation. Spatial profile of the potential around the interface was
+deduced, including the charge-depletion width of 2.3 nm extending on the ZnO
+side and the built-in potential of 0.54 eV.",0604549v1
+2006-05-12,Surfactant assisted synthesis of Co and Li doped ZnO nanocrystalline samples showing room temperature ferromagnetism,"We have developed a simple, surfactant assisted synthesis route for the
+preparation, in gram quantities, of Co and Li doped ZnO nanocrystalline samples
+showing robust room temperature ferromagnetism. Our studies show that RTF is
+intrinsic to Zn0.85Co0.05Li0.10O and not due to any segregated secondary
+phases. In addition, it has been shown that the defects play an important role
+in activating RTF in these oxide systems. This also provide an explanation for
+the widely varying results observed in the literature. The method can also be
+extended for the synthesis of other transition metal doped ZnO.",0605332v1
+2006-05-26,Role of Inelastic Tunneling through the Barrier in Scanning Tunneling Microscope Experiments on Cuprates,"The tunneling path between the CuO2-layers in cuprate superconductors and a
+scanning tunneling microscope tip passes through a barrier made from other
+oxide layers. This opens up the possibility that inelastic processes in the
+barrier contribute to the tunneling spectra. Such processes cause one or
+possibly more peaks in the second derivative current-voltage spectra displaced
+by phonon energies from the density of states singularity associated with
+superconductivity. Calculations of inelastic processes generated by apical
+O-phonons show good qualitative agreement with recent experiments reported by
+Lee et al.[1]. Further tests to discriminate between these inelastic processes
+and coupling to planar phonons are proposed.",0605646v1
+2006-06-09,Current spinon-holon description of the one-dimensional charge-transfer insulator SrCuO2: Angle-resolved photoemission measurements,"We have investigated the low-energy electronic structure of the strongly
+correlated one-dimensional copper oxide chain compound SrCuO2 by angle resolved
+photoemission as a function of excitation energy. In addition to the prominent
+spinon-holon continuum we observe a peaklike and dispersive feature at the zone
+boundary. By fine-tuning the experimental parameters we are able to monitor the
+full holon branch and to directly measure the electronic hopping parameter with
+unprecedented accuracy.",0606238v1
+2006-06-15,"Microscopic Reversibility, Space-Filling, and Internal Stress in Strong Glasses","The axiomatic theory of ideally glassy networks, which has proved effective
+in describing phase diagrams and many properties of chalcogenide, oxide, and
+even molecular glasses, is here broadened to describe both geometrical
+properties, such as the first sharp diffraction peak, and kinetic properties,
+such as the nonreversible enthalpy of the glass transition, as measured by
+modulated differential scanning calorimetry. The discussion shows why the
+latter is such an effective tool for identifying strong glasses.",0606418v1
+2006-06-23,Resonant X-ray diffraction studies on the charge ordering in magnetite,"Here we show that the low temperature phase of magnetite is associated with
+an effective, although fractional, ordering of the charge. Evidence and a
+quantitative evaluation of the atomic charges are achieved by using resonant
+x-ray diffraction (RXD) experiments whose results are further analyzed with the
+help of ab initio calculations of the scattering factors involved. By
+confirming the results obtained from X-ray crystallography we have shown that
+RXD is able to probe quantitatively the electronic structure in very complex
+oxides, whose importance covers a wide domain of applications.",0606596v1
+2006-08-04,Optical Sum Rule in Finite Bands,"In a single finite electronic band the total optical spectral weight or
+optical sum carries information on the interactions involved between the charge
+carriers as well as on their band structure. It varies with temperature as well
+as with impurity scattering. The single band optical sum also bears some
+relationship to the charge carrier kinetic energy and, thus, can potentially
+provide useful information, particularly on its change as the charge carriers
+go from normal to superconducting state. Here we review the considerable
+advances that have recently been made in the context of high $T_c$ oxides, both
+theoretical and experimental.",0608116v1
+2006-08-24,The nature of ferroelectricity under pressure,"Advances in first-principles computational approaches have, over the past
+fifteen years, made possible the investigation of physical properties of
+ferroelectric systems. In particular, such approaches have led to a microscopic
+understanding of the occurrence of ferroelectricity in perovskite oxides at
+ambient pressure. In this paper, we report ab-initio studies on the effect of
+hydrostatic pressure on the ferroelectricity in perovskites and related
+materials. We found that, unlike commonly believed, these materials exhibit
+ferroelectricity at high enough pressure. We also explained in details the
+(unusual) nature of this ferroelectricity.",0608530v1
+2006-10-13,Coexistence of polar order and local domain dynamics in ferroelectric SrTi18O3,"Perovskite oxide ferroelectrics show classical soft mode behaviour typical
+for the onset of a homogeneous long-range polar state and a displacive phase
+transition. Besides these long wave length properties, local effects are
+observed by different probes which reveal that dynamical symmetry breaking
+already takes place already far above the actual instability. It is shown here
+that displacive mean-field type dynamics can indeed coexist with local
+dynamical symmetry breaking.",0610362v1
+2006-10-31,Temperature and field dependence of Dynamics in the Electron-Glass,"We describe several experimental methods to quantify dynamics in electron
+glasses and illustrate their use in the glassy phase of crystalline
+indium-oxide films. These methods are applied to study the dependence of
+dynamics on temperature and on non-ohmic electric fields at liquid helium
+temperatures. It is shown that over a certain range of temperature the dynamics
+becomes slower with temperature or upon increasing an applied non-ohmic field,
+a behavior suggestive of a quantum-glass. It is demonstrated that non-ohmic
+fields produce qualitatively similar results as raising the system temperature.
+Quantitatively however, their effect may differ marekdly. The experimental
+advantages of using fields to mimic higher temperature are pointed out and
+illustrated.",0610859v1
+2006-11-02,Field-effect transistors assembled from functionalized carbon nanotubes,"We have fabricated field effect transistors from carbon nanotubes using a
+novel selective placement scheme. We use carbon nanotubes that are covalently
+bound to molecules containing hydroxamic acid functionality. The functionalized
+nanotubes bind strongly to basic metal oxide surfaces, but not to silicon
+dioxide. Upon annealing, the functionalization is removed, restoring the
+electronic properties of the nanotubes. The devices we have fabricated show
+excellent electrical characteristics.",0611051v1
+2006-12-21,Photoinduced charge and spin dynamics in strongly correlated electron systems,"Motivated by photoinduced phase transition in manganese oxides, charge and
+spin dynamics induced by photoirradiation are examined. We calculate the
+transient optical absorption spectra of the extended double-exchange model by
+the density matrix renormalization group (DMRG) method. A charge-ordered
+insulating (COI) state becomes metallic just after photoirradiation, and the
+system tends to recover the initial COI state. The recovery is accompanied with
+remarkable suppression of an antiferromagnetic correlation in the COI state.
+The DMRG results are consistent with recent pump-probe spectroscopy data.",0612540v1
+2007-03-05,Orbital correlations in monolayer manganites - From spin t-J model to orbital t-J model,"On the example of monolayer manganites we show that the theoretical ideas
+developed long ago along the derivation of the spin t-J model from the Hubbard
+model are nowadays very helpful in strongly correlated oxides with partly
+filled degenerate orbitals. We analyze a realistic orbital t-J model for e_g
+electrons in La_{1-x}Sr_{1+x}MnO_4 monolayer manganites, and discuss the
+evolution of spin and orbital correlations under increasing doping by
+performing exact diagonalization of finite clusters, with electronic kinetic
+energy determined self-consistently at finite temperature by classical Monte
+Carlo for t_2g spins. Several experimental results are reproduced.",0703127v1
+1999-03-14,Precision Crystal Calorimetry in High Energy Physics,"Crystal Calorimetry is widely used in high energy physics because of its
+precision. Recent development in crystal technology identified two key issues
+to reach and maintain crystal precision: light response uniformity and
+calibration in situ. Crystal radiation damage is understood. While the damage
+in alkali halides is found to be caused by the oxygen/hydroxyl contamination,
+it is the structure defects, such as oxygen vacancies, cause damage in oxides.",9903023v1
+1999-09-10,Supersensitive avalanche silicon drift photodetector,"Physical principles of performance and main characteristics of a novel
+avalanche photodetector developed on the basis of MOS(metal-oxide-silicon)
+technology is presented. The photodetector contains a semitransparent gate
+electrode and a drain contact to provide a drift of multiplicated charge
+carriers along the semiconductor surface. A high gain(more than 10^4) of
+photocurrent was achived due to the local negative feedback effect realizied on
+the Si-SiO_2 boundary. Special attention is paid to the possibilities of
+development of a supersensitive avalanche CCD (charge coupled device) for
+detection of individual photons in visible and ultraviolet spectral regions.
+Experimental results obtained with a two-element CCD prototype are discussed.",9909017v1
+1995-12-10,Rusty Scatter Branes,"We derive double dimensional reduction/oxidation in a framework where it is
+applicable to describe general non-static (and anisotropic) $p$-brane
+solutions. Given this procedure, we are able to relate the dynamical
+interaction potential for parallel extremal $p$-branes in $D$ dimensions to
+that for extremal black holes in $D-p$ dimensions. In particular, we find that
+to leading order the potential vanishes for all $\kappa$-symmetric $p$-branes.",9512061v1
+2002-03-01,Revisiting Supergravity and Super Yang-Mills Renormalization,"Standard superspace Feynman diagram rules give one estimate of the onset of
+ultraviolet divergences in supergravity and super Yang-Mills theories. Newer
+techniques motivated by string theory but which also make essential use of
+unitarity cutting rules give another in certain cases. We trace the difference
+to the treatment of higher-dimensional gauge invariance in supersymmetric
+theories that can be dimensionally oxidized to pure supersymmetric gauge
+theories.",0203015v1
+2002-08-07,Domain Walls and Spaces of Special Holonomy,"We review the relations between a family of domain-wall solutions to M-theory
+and gravitational instantons with special holonomy. When oxidized into the
+maximal-dimension parent supergravity, the transverse spaces of these domain
+walls become cohomogeneity-one spaces with generalized Heisenberg symmetries
+and a homothetic conformal symmetry. These metrics may also be obtained as
+scaling limits of generalized Eguchi-Hanson metrics, or, with appropriate
+discrete identifications, from generalized Atiyah-Hitchin metrics, thus
+providing field-theoretic realizations of string-theory orientifolds.",0208055v1
+2003-09-10,The topology of U-duality (sub-)groups,"We discuss the topology of the symmetry groups appearing in compactified
+(super-)gravity, and discuss two applications. First, we demonstrate that for 3
+dimensional sigma models on a symmetric space G/H with G non-compact and H the
+maximal compact subgroup of G, the possibility of oxidation to a higher
+dimensional theory can immediately be deduced from the topology of H. Second,
+by comparing the actual symmetry groups appearing in maximal supergravities
+with the subgroups of SL(32,R) and Spin(32), we argue that these groups cannot
+serve as a local symmetry group for M-theory in a formulation of de Wit-Nicolai
+type.",0309106v1
+2005-01-11,Eleven-Dimensional Supergravity in Light-Cone Superspace,"We show that Supergravity in eleven dimensions can be described in terms of a
+constrained superfield on the light-cone, without the use of auxiliary fields.
+We build its action to first order in the gravitational coupling constant
+\kappa, by ""oxidizing"" (N=8,d=4) Supergravity. This is simply achieved, as for
+N=4 Yang-Mills, by extending the transverse derivatives into superspace. The
+eleven-dimensional SuperPoincare algebra is constructed and a fourth order
+interaction is conjectured.",0501079v2
+2004-10-21,Equation-free optimal switching policies for bistable reacting systems using coarse time-steppers,"We present a computer-assisted approach to locating approximate coarse
+optimal switching policies between stationary states of chemically reacting
+systems described by microscopic/stochastic evolution rules. The ``coarse
+time-stepper"" constitutes a bridge between the underlying kinetic Monte Carlo
+simulation and traditional, continuum numerical optimization techniques
+formulated in discrete time. The approach is illustrated through two simple
+catalytic surface reaction models, implemented through kinetic Monte Carlo: NO
+reduction on Pt, and CO oxidation on Pt. The objective sought in both cases is
+to switch between two coexisting stable stationary states by minimal
+manipulation of a macroscopic system parameter.",0410467v1
+2005-11-28,Geometry-induced pulse instability in microdesigned catalysts: the effect of boundary curvature,"We explore the effect of boundary curvature on the instability of reactive
+pulses in the catalytic oxidation of CO on microdesigned Pt catalysts. Using
+ring-shaped domains of various radii, we find that the pulses disappear
+(decollate from the inert boundary) at a turning point bifurcation, and trace
+this boundary in both physical and geometrical parameter space. These
+computations corroborate experimental observations of pulse decollation.",0511063v1
+2005-12-08,Guiding chemical pulses through geometry: Y-junctions,"We study computationally and experimentally the propagation of chemical
+pulses in complex geometries.The reaction of interest, CO oxidation, takes
+place on single crystal Pt(110) surfaces that are microlithographically
+patterned; they are also addressable through a focused laser beam, manipulated
+through galvanometer mirrors, capable of locally altering the crystal
+temperature and thus affecting pulse propagation. We focus on sudden changes in
+the domain shape (corners in a Y-junction geometry) that can affect the pulse
+dynamics; we also show how brief, localized temperature perturbations can be
+used to control reactive pulse propagation.The computational results are
+corroborated through experimental studies in which the pulses are visualized
+using Reflection Anisotropy Microscopy.",0512019v1
+2000-10-04,Dynamics of Chemical Reactions: Open Equilibrium,"Dynamic properties of chemical reactions and appropriate relationships for
+open chemical equilibrium are discussed in approach of the chemical dynamics.
+New way to calculate composition of chemical systems in open equilibrium, based
+on the amended equation for the change of Gibbs' free energy, was exemplified
+using reactions of cobalt double oxides with sulfur. Evaluated this way
+equilibrium reaction extents had a good match with values found by direct
+thermodynamic simulation. The developed method allows us to perform analysis of
+complex chemical systems without coefficients of thermodynamic activity. In
+cases when the coefficients are in need or just desirable, the method offers a
+simple way to calculate them. Possible systems to apply method of chemical
+dynamics are discussed.",0010013v2
+2001-04-23,Adsorption of CO on a Platinum (111) surface - a study within a four-component relativistic density functional approach,"We report on results of a theoretical study of the adsorption process of a
+single carbon oxide molecule on a Platinum (111) surface. A four-component
+relativistic density functional method was applied to account for a proper
+description of the strong relativistic effects. A limited number of atoms in
+the framework of a cluster approach is used to describe the surface. Different
+adsorption sites are investigated. We found that CO is preferably adsorbed at
+the top position.",0104071v1
+2003-01-18,Fundamental building blocks of eumelanins: electronic properties of indolequinone-dimers,"We present results from the theoretical INDO calculations of the electronic
+structure for stacked eumelanins' monomers. As basic indolic components of the
+eumelanin structure 5,6-dihydroxyindole (DHI or HQ) and its oxidized forms (SQ
+and IQ) were chosen. The results reveal dependency of electronic properties of
+such aggregates on monomers' redox states. They point out also a tendency to
+localize an extra charge on one of dimer's subunits that could be suggestive of
+an electron hopping as a model mechanism forthe electron transfer in
+eumelanins.",0301042v1
+2004-06-01,Ultraviolet photonic crystal laser,"We fabricated two dimensional photonic crystal structures in zinc oxide films
+with focused ion beam etching. Lasing is realized in the near ultraviolet
+frequency at room temperature under optical pumping. From the measurement of
+lasing frequency and spatial profile of the lasing modes, as well as the
+photonic band structure calculation, we conclude that lasing occurs in the
+strongly localized defect modes near the edges of photonic band gap. These
+defect modes originate from the structure disorder unintentionally introduced
+during the fabrication process.",0406005v1
+2005-10-25,Equations for filling factor estimation in opal matrix,"We consider two equations for the filling factor estimation of infiltrated
+zinc oxide (ZnO) in silica (SiO_2) opal and gallium nitride in ZnO opal. The
+first equation is based on the effective medium approximation, while the second
+one - on Maxwell-Garnett approximation. The comparison between two filling
+factors shows that both equations can be equally used for the estimation of the
+quantity of infiltrated nanocrystals inside opal matrix.",0510230v2
+2006-08-10,Analysis of surface waves generated on subwavelength-structured silver films,"Using transmission electron microscopy (TEM) to analyse the physical-chemical
+surface properties of subwavlength structured silver films and
+finite-difference time-domain (FDTD) numerical simulations of the optical
+response of these structures to plane-wave excitation, we report on the origin
+and nature of the persistent surface waves generated by a single slit-groove
+motif and recently measured by far-field optical interferometry. The surface
+analysis shows that the silver films are free of detectable oxide or sulfide
+contaminants, and the numerical simulations show very good agreement with the
+results previously reported.",0608116v2
+2006-12-19,N_2O weak lines observed between 3900 and 4050 cm^-1 from long path absorption spectra,"Previously unobserved nitrous oxide transitions around 2.5 $\mu$m are
+measured by intracavity laser absorption spectroscopy (ICLAS) analyzed by
+time-resolved Fourier transform (TRFT) spectrometer. With an accuracy of the
+order of 10^-3 cm^-1, measured positions of 1637 assigned weak transitions are
+provided. They belong to 42 vibrational transitions, among which 33 are
+observed for the first time. These data are believed to be useful in particular
+to monitoring atmosphere purposes.",0612181v1
+1995-01-19,Phonon Assisted Multimagnon Optical Absorption and Long Lived Two-Magnon States in Undoped Lamellar Copper Oxides,"We calculate the effective charge for multimagnon infrared (IR) absorption
+assisted by phonons in the parent insulating compounds of cuprate
+superconductors and the spectra for two-magnon absorption using interacting
+spin-wave theory. Recent measured bands in the mid IR [Perkins et al. Phys.
+Rev. Lett. {\bf 71} 1621 (1993)] are interpreted as involving one phonon plus a
+two-magnon virtual bound state, and one phonon plus higher multimagnon
+absorption processes. The virtual bound state consists of a narrow resonance
+occurring when the magnon pair has total momentum close to $(\pi,0)$.",9501001v1
+2007-04-05,Evidence of Spatially Inhomogeous Pairing on the Insulating Side of a Disorder-Tuned Superconductor-Insulator Transition,"Measurements of transport properties of amorphous insulating indium oxide
+thin films have been interpreted as evidence of the presence of superconducting
+islands on the insulating side of a disorder-tuned superconductor-insulator
+transition. Although the films are not granular, the behavior is similar to
+that observed in granular films. The results support theoretical models in
+which the destruction of superconductivity by disorder produces spatially
+inhomogenous pairing with a spectral gap.",0704.0765v2
+2007-04-09,Electrical transport properties of polar heterointerface between KTaO3 and SrTiO3,"Electrical transport of a polar heterointerface between two insulating
+perovskites, KTaO3 and SrTiO3, is studied. It is formed between a thin KTaO3
+film deposited on a top of TiO2- terminated (100) SrTiO3 substrate. The
+resulting (KO)1-(TiO2)0 heterointerface is expected to be hole-doped according
+to formal valences of K (1+) and Ti (4+). We observed electrical conductivity
+and mobility in the KTaO3/SrTiO3 similar to values measured earlier in
+electron-doped LaAlO3/SrTiO3 heterointerfaces. However, the sign of the charge
+carriers in KTaO3/SrTiO3 obtained from the Hall measurements is negative. The
+result is an important clue to the true origin of the doping at perovskite
+oxide hetero-interfaces.",0704.1050v1
+2007-04-11,Surface Structure Analysis of Atomically Smooth BaBiO$_3$ Films,"Using low energy Time-of-Flight Scattering and Recoil Spectroscopy (TOF-SARS)
+and Mass Spectroscopy of Recoiled Ions (MSRI) we analyze the surface structure
+of an atomically smooth BaBiO$_3$ film grown by molecular beam epitaxy. We
+demonstrate high sensitivity of the TOF-SARS and MSRI spectra to slight changes
+in the orientation of the ion scattering plane with respect to the
+crystallographic axes. The observed angle dependence allows us to clearly
+identify the termination layer as BiO$_2$. Our data also indicate that
+angle-resolved MSRI data can be used for high resolution studies of surface
+structure of complex oxide thin films.",0704.1501v1
+2007-04-26,Quantum Hall Effect in a Graphene p-n Junction,"We report on the fabrication and transport studies of a single-layer graphene
+p-n junction. Carrier type and density in two adjacent regions are individually
+controlled by electrostatic gating using a local top gate and a global back
+gate. A functionalized Al203 oxide that adheres to graphene and does not
+significantly affect its electronic properties is described. Measurements in
+the quantum Hall regime reveal new plateaus of two-terminal conductance across
+the junction at 1 and 3/2 times the quantum of conductance, e2/h, consistent
+with theory.",0704.3487v2
+2007-05-01,Visibility of graphene flakes on a dielectric substrate,"We model the optical visibility of monolayer and bilayer graphene deposited
+on a silicon/silicon oxide substrate or thermally annealed on the surface of
+silicon carbide. We consider reflection and transmission setups, and find that
+visibility is strongest in reflection reaching the optimum conditions when the
+bare substrate transmits light resonantly. In the optical range of frequencies
+a bilayer is approximately twice as visible as a monolayer thereby making the
+two types of graphene distinguishable from each other.",0705.0091v2
+2007-05-15,Growth control of GaAs nanowires using pulsed laser deposition with arsenic over pressure,"Using pulsed laser ablation with arsenic over pressure, the growth conditions
+for GaAs nanowires have been systematically investigated and optimized. Arsenic
+over pressure with As$_2$ molecules was introduced to the system by thermal
+decomposition of polycrystalline GaAs to control the stoichiometry and shape of
+the nanowires during growth. GaAs nanowires exhibit a variety of geometries
+under varying arsenic over pressure, which can be understood by different
+growth processes via vapor-liquid-solid mechanism. Single-crystal GaAs
+nanowires with uniform diameter, lengths over 20 $\mu$m, and thin surface oxide
+layer were obtained and can potentially be used for further electronic
+characterization.",0705.2181v1
+2007-06-14,Use of detailed kinetic mechanisms for the prediction of autoignitions,"This paper describes how automatically generated detailed kinetic mechanisms
+are obtained for the oxidation of alkanes and how these models could lead to a
+better understanding of autoignition and cool flame risks at elevated
+conditions. Examples of prediction of the occurrence of different autoignition
+phenomena, such as cool flames or two-stage ignitions are presented depending
+on the condition of pressure, temperature and mixture composition. Three
+compounds are treated, a light alkane, propane, and two heavier ones, n-heptane
+and n-decane.",0706.2067v1
+2007-06-22,Transition metal oxides using quantum Monte Carlo,"The transition metal-oxygen bond appears prominently throughout chemistry and
+solid-state physics. Many materials, from biomolecules to ferroelectrics to the
+components of supernova remnants contain this bond in some form. Many of these
+materials' properties strongly depend on fine details of the TM-O bond and
+intricate correlation effects, which make accurate calculations of their
+properties very challenging. We present quantum Monte Carlo, an explicitly
+correlated class of methods, to improve the accuracy of electronic structure
+calculations over more traditional methods like density functional theory. We
+find that unlike s-p type bonding, the amount of hybridization of the d-p bond
+in TM-O materials is strongly dependant on electronic correlation.",0706.3380v1
+2007-06-28,Effect of physical inactivity on the oxidation of saturated and monounsaturated dietary Fatty acids: results of a randomized trial,"OBJECTIVES: Changes in the way dietary fat is metabolized can be considered
+causative in obesity. The role of sedentary behavior in this defect has not
+been determined. We hypothesized that physical inactivity partitions dietary
+fats toward storage and that a resistance exercise training program mitigates
+storage.",0706.4219v1
+2007-06-29,A simple model of Coulomb disorder and screening in graphene,"We suggest a simple model of disorder in graphene assuming that there are
+randomly distributed positive and negative centers with equal concentration
+$N/2$ in the bulk of silicon oxide substrate. We show that at zero gate voltage
+such disorder creates two-dimensional concentration $n_0 \sim N^{2/3}$ of
+electrons and holes in graphene. Electrons and holes reside in alternating in
+space puddles of the size $R_0 \sim N^{-1/3}$. A typical puddle has only one or
+two carriers in agreement with recent scanning single electron transistor
+experiment.",0706.4425v3
+2007-07-03,Surface Encapsulation for Low-Loss Silicon Photonics,"Encapsulation layers are explored for passivating the surfaces of silicon to
+reduce optical absorption in the 1500-nm wavelength band. Surface-sensitive
+test structures consisting of microdisk resonators are fabricated for this
+purpose. Based on previous work in silicon photovoltaics, coatings of SiNx and
+SiO2 are applied under varying deposition and annealing conditions. A short dry
+thermal oxidation followed by a long high-temperature N2 anneal is found to be
+most effective at long-term encapsulation and reduction of interface
+absorption. Minimization of the optical loss is attributed to simultaneous
+reduction in sub-bandgap silicon surface states and hydrogen in the capping
+material.",0707.0415v1
+2007-07-04,Role of oxygen vacancies in Cr-doped SrTiO3 for resistance-change memory,"Transition-metal oxides exhibiting a bistable resistance state are attractive
+for non-volatile memory applications. The relevance of oxygen vacancies (VO)
+for the resistance-change memory was investigated with x-ray fluorescence,
+infrared microscopy, and x-ray absorption spectroscopy using Cr-doped SrTiO3 as
+example. We propose that the microscopic origin of resistance switching in this
+class of materials is due to an oxygen-vacancy drift occurring in close
+proximity to one of the electrodes.",0707.0563v1
+2007-07-05,Observation of a uniform temperature dependence in the electrical resistance across the structural phase transition in thin film vanadium oxide ($VO_{2}$),"An electrical study of thin $VO_{2}$ films in the vicinity of the structural
+phase transition at $68^{0}C$ shows (a) that the electrical resistance $R$
+follows $log (R)$ $\propto$ $-T$ over the $T$-range, $20 < T < 80 ^{0}C$
+covering both sides of the structural transition, and (b) a history dependent
+hysteresis loop in $R$ upon thermal cycling. These features are attributed here
+to transport through a granular network.",0707.0885v1
+2007-07-31,Quantum phase transition in the two-band Hubbard model,"The interaction between itinerant and Mott localized electronic states in
+strongly correlated materials is studied within dynamical mean field theory in
+combination with the numerical renormalization group method. A novel
+nonmagnetic zero temperature quantum phase transition is found in the
+bad-metallic orbital-selective Mott phase of the two-band Hubbard model, for
+values of the Hund's exchange which are relevant to typical transition metal
+oxides.",0707.4535v2
+2007-08-03,Spin polaron theory for the photoemission spectra of layered cobaltates,"Recently, strong reduction of the quasiparticle peaks and pronounced
+incoherent structures have been observed in the photoemission spectra of
+layered cobaltates. Surprisingly, these many-body effects are found to increase
+near the band insulator regime. We explain these unexpected observations in
+terms of a novel spin-polaron model for CoO_2 planes which is based on a fact
+of the spin-state quasidegeneracy of Co^{3+} ions in oxides. Scattering of the
+photoholes on spin-state fluctuations suppresses their coherent motion. The
+observed ``peak-dip-hump'' type lineshapes are well reproduced by the theory.",0708.0543v1
+2007-08-09,Antiferromagnetic fluctuations in the superconducting phase of low- and high-temperature superconductors,"Based on recent experimental results for electron-doped cuprate oxides and
+ferromagnetic superconductors, it is shown that antiferromagnetic fluctuations
+always develop in the superconducting phase of both low- and high-temperature
+superconductors. The relation between the magnitude of the antiferromagnetic
+pseudogap and the characteristic temperature of the antiferromagnetic pseudogap
+opening is obtained. The characteristic temperature of the antiferromagnetic
+pseudogap opening for metal superconductors is estimated.",0708.1230v3
+2007-08-09,Electroluminescence from single nanowires by tunnel injection: an experimental study,"We present a hybrid light-emitting diode structure composed of an n-type
+gallium nitride nanowire on a p-type silicon substrate in which current is
+injected along the length of the nanowire. The device emits ultraviolet light
+under both bias polarities. Tunnel-injection of holes from the p-type substrate
+(under forward bias) and from the metal (under reverse bias) through thin
+native oxide barriers consistently explains the observed electroluminescence
+behaviour. This work shows that the standard p-n junction model is generally
+not applicable to this kind of device structure.",0708.1266v1
+2007-08-21,Scale dependent superconductor-insulator transition,"We study the disorder driven superconductor to insulator transition in
+amorphous films of high carrier-concentration indium-oxide. Using thin films
+with various sizes and aspect ratios we show that the `critical'
+sheet-resistance $R_{{\small \square}}$ depends systematically on sample
+geometry; superconductivity disappears when $R_{{\small \square}}$ exceeds
+$\approx6 $k$\Omega$ in large samples. On the other hand, wide and sufficiently
+short samples of the same batch exhibit superconductivity (judged by
+conductivity versus temperature) up to $R_{{\small \square}}$ which is
+considerably larger. These results support the inhomogeneous scenario for the
+superconductor-insulator transition.",0708.2751v1
+2007-08-24,"Ab-initio calculation of the vibrational modes of SiH4, H2SiO, Si10H16, and Si10H14O","We have studied the normal modes of hydrogenated and oxidized silicon
+nanocrystals, namely SiH4 (silan), H2SiO (silanon), Si10H16 and Si10H14O. The
+small clusters (SiH4 and H2SiO) have been used for convergence tests and their
+bondlengths and frequencies have been compared with experimental and
+theoretical reference data. For the large clusters (Si10H16 and Si10H14O) we
+have investigated the vibrational density of states where we have identified
+the oxygen-related spectral features. The vibrational modes have been also
+analyzed with respect to the displacement patterns. The calculations have been
+carried out within the density-functional and density-functional perturbation
+theory using the local-density approximation.",0708.3312v1
+2007-08-25,Does Simple Two-Dimensional Hubbard Model Account for High-Tc Superconductivity in Copper Oxides?,"We reexamine whether the essence of high-Tc superconductivity is contained in
+doped Hubbard models on the square lattice by using recently developed
+pre-projected Gaussian-basis Monte Carlo method. The superconducting
+correlations of the dx2-y2 wave symmetry in the ground state at distance r
+decays essentially as inverse cubic of r. The upper bound of the correlation at
+long distances estimated by this unbiased method is 0.001, indicating that
+recent extensions of dynamical mean-field theories and variational methods
+yielded at least an order of magnitude overestimates of it. The correlations
+are too weak for the realistic account of the cuprate high-Tc
+superconductivity.",0708.3416v1
+2007-09-11,Electronic transport in locally gated graphene nanoconstrictions,"We have developed the combination of an etching and deposition technique that
+enables the fabrication of locally gated graphene nanostructures of arbitrary
+design. Employing this method, we have fabricated graphene nanoconstrictions
+with local tunable transmission and characterized their electronic properties.
+An order of magnitude enhanced gate efficiency is achieved adopting the local
+gate geometry with thin dielectric gate oxide. A complete turn off of the
+device is demonstrated as a function of the local gate voltage. Such strong
+suppression of device conductance was found to be due to both quantum
+confinement and Coulomb blockade effects in the constricted graphene
+nanostructures.",0709.1731v1
+2007-09-13,Observation of the Purcell effect in high-index-contrast micropillar,"We have fabricated pillar microcavity samples with Bragg mirrors consisting
+of alternate layers of GaAs and Aluminium Oxide. Compared to the more widely
+studied GaAs/AlAs micropillars these mirrors can achieve higher reflectivities
+with fewer layer repeats and reduce the mode volume. We have studied a number
+of samples containing a low density of InGaAs/GaAs self assembled quantum dots
+in a cavity and here report observation of a three fold enhancement in the
+radiative lifetime of a quantum dot exciton state due to the Purcell effect.",0709.2101v1
+2007-11-27,Integrating Superconductive and Optical Circuits,"We have integrated on oxidized silicon wafers superconductive films and
+Josephson junctions along with sol-gel optical channel waveguides. The
+fabrication process is carried out in two steps that result to be solid and
+non-invasive. It is demonstrated that 660 nm light, coupled from an optical
+fibre into the channel sol-gel waveguide, can be directed toward
+superconducting tunnel junctions whose current-voltage characteristics are
+affected by the presence of the radiation. The dependence of the change in the
+superconducting energy gap under optical pumping is discussed in terms of a
+non-equilibrium superconductivity model.",0711.4221v1
+2007-12-19,Decomposition and Oxidation of the N-Extended Supersymmetric Quantum Mechanics Multiplets,"We furnish an algebraic understanding of the inequivalent connectivities
+(computed up to $N\leq 10$) of the graphs associated to the irreducible
+supermultiplets of the N-extended Supersymmetric Quantum Mechanics. We prove
+that the inequivalent connectivities of the N=5 and N=9 irreducible
+supermultiplets are due to inequivalent decompositions into two sets of N=4
+(respectively, N=8) supermultiplets. ""Oxido-reduction"" diagrams linking the
+irreducible supermultiplets of the N=5,6,7,8 supersymmetries are presented. We
+briefly discuss these results and their possible applications.",0712.3176v1
+2007-12-30,Characterization of ZnO:Si Nanocomposite Films Grown by Thermal Evaporation,"Nanocomposite thin films of Zinc Oxide and Silicon were grown by
+co-evaporating powdered ZnO and Si. This resulted in nanocrystallites of ZnO
+being embedded in Silicon. The mismatch in crystal structures of constituent
+materials result in the ZnO nanocrystals to exist in a state of stress. This
+along with oxygen vacancies in the samples result in good Photoluminescence
+emission at 520nm. Also, Silicon background gave a photoluminescence emission
+at 620nm. The structure was found quite stable over time since the homgenously
+dispersed ZnO nanocrystals do not agglomerate. The nanocomposites promises to
+be a useful candidate for future optoelectronic devices.",0801.0144v1
+2008-01-25,Free-running InGaAs/InP Avalanche Photodiode with Active Quenching for Single Photon Counting at Telecom Wavelengths,"We present an InGaAs/InP avalanche photodiode with an active quenching
+circuit on an ASIC (application specific integrated circuit) that is capable of
+operating in both gated and free-running modes. The 1.6mm2 ASIC chip is
+fabricated using CMOS (complementary metal oxide semiconductor) technology
+guaranteeing long-term stability, reliability and compactness. In the
+free-running mode we find a single photon detection efficiency of 10% with
+<2kHz of noise.",0801.3899v1
+2008-02-04,Logic Ciucuits Using Solution-processed Single-walled Carbon Nanotue Transistors,"This letter reports on the realization of logic circuits employing
+solution-processed networks of single-walled carbon nanotubes. We constructed
+basic logic gates (inverter, NAND and NOR) with n- and p-type field-effect
+transistors fabricated by solution-based chemical doping. Complementary
+metal-oxide-semiconductor inverters exhibited voltage gains of up to 20, which
+illustrates the great potential of carbon nanotube networks for printable
+flexible electronics.",0802.0334v1
+2008-02-14,Absence of Hole Confinement in Transition Metal Oxides with Orbital Degeneracy,"We investigate the spectral properties of a hole moving in a two-dimensional
+Hubbard model for strongly correlated t_2g electrons. Although superexchange
+interactions are Ising-like, a quasi-one-dimensional coherent hole motion
+arises due to effective three-site terms. This mechanism is fundamentally
+different from the hole motion via quantum fluctuations in the conventional
+spin model with SU(2) symmetry. The orbital model describes also propagation of
+a hole in some e_g compounds, and we argue that orbital degeneracy alone does
+not lead to hole self-localization.",0802.2012v1
+2008-02-26,Wide-field Fourier transform spectral imaging,"We report experimental results of parallel measurement of spectral components
+of the light. The temporal fluctuations of an optical field mixed with a
+separate reference are recorded with a high throughput complementary metal
+oxide semi-conductor camera (1 Megapixel at 2 kHz framerate). A numerical
+Fourier transform of the time-domain recording enables wide-field coherent
+spectral imaging. Qualitative comparisons with frequency-domain wide-field
+laser Doppler imaging are provided.",0802.3773v1
+2008-03-28,Abrupt boundaries of intermediate phases and space filling in oxide glasses,"Modulated DSC measurements on bulk (Na2O)x(GeO2)1-x glasses show a sharp
+reversibility window in the 14% < x < 19% soda range, which correlates well
+with a broad global minimum in molar volumes. Raman and IR reflectance TO and
+LO mode frequencies exhibit anomalies between xc(1) = 14% (stress transition)
+and xc(2) = 19% (rigidity transition), with optical elasticity power-laws
+confirming the nature of the transitions . Birefringence measurements dramatize
+the macroscopically stress-free nature of the Intermediate Phase in the
+reversibility window.",0803.4109v1
+2008-04-03,Understanding the Unique Structural and Electronic Properties of SrFeO2,"We report a first-principles study of SrFeO$_2$, an infinite-layer oxide with
+Fe atoms in a perfect square-planar coordination down to essentially 0 K. Our
+results reveal this striking behavior relies on the double occupation of the
+3$d_{z^2}$ orbitals of high-spin Fe$^{2+}$. Such an electronic state results
+from the hybridization of iron's 3$d_{z^2}$ and 4$s$ orbitals, which enables a
+large reduction of the intra-atomic exchange splitting of the $z^2$ electrons.
+The generality of the phenomenon is discussed.",0804.0495v1
+2008-04-24,"Spin, Orbital and Charge Order at the Interface between Correlated Oxides","The collective behavior of correlated electrons in the VO$_2-$interface layer
+of LaVO$_3$/SrTiO$_3$ heterostructure is studied within a quarter-filled
+$t_{2g}$-orbital Hubbard model on a square lattice. We argue that the ground
+state is ferromagnetic driven by the double exchange mechanism, and is
+orbitally and charge ordered due to a confined geometry and electron
+correlations. The orbital and charge density waves open gaps on the entire
+Fermi surfaces of all orbitals. The theory explains the observed insulating
+behavior of the $p$-type interface between LaVO$_3$ and SrTiO$_3$.",0804.3974v2
+2008-05-28,Dielectric and polarization experiments in high loss dielectrics: a word of caution,"The recent quest for improved functional materials like high permittivity
+dielectrics and/or multiferroics has triggered an intense wave of research.
+Many materials have been checked for their dielectric permittivity or their
+polarization state. In this report, we call for caution when samples are
+simultaneously displaying insulating behavior and defect-related conductivity.
+Many oxides containing mixed valent cations or oxygen vacancies fall in this
+category. In such cases, most of standard experiments may result in effective
+high dielectric permittivity which cannot be related to ferroelectric
+polarization. Here we list few examples of possible discrepancies between
+measured parameters and their expected microscopic origin.",0805.4335v1
+2008-06-03,A gate-defined silicon quantum dot molecule,"We report electron transport measurements of a silicon double dot formed in
+multi-gated metal-oxide-semiconductor structures with a 15-nm-thick
+silicon-on-insulator layer. Tunable tunnel coupling enables us to observe an
+excitation spectrum in weakly coupled dots and an energy level anticrossing in
+strongly coupled ones. Such a quantum dot molecule with both charge and energy
+quantization provides the essential prerequisite for future implementation of
+silicon-based quantum computations.",0806.0422v1
+2008-06-18,Diffusion based degradation mechanisms in giant magnetoresistive spin valves,"Spin valve systems based on the giant magnetoresistive (GMR) effect as used
+for example in hard disks and automotive applications consist of several
+functional metallic thin film layers. We have identified by secondary ion mass
+spectrometry (SIMS) two main degradation mechanisms: One is related to oxygen
+diffusion through a protective cap layer, and the other one is interdiffusion
+directly at the functional layers of the GMR stack. By choosing a suitable
+material as cap layer (TaN), the oxidation effect can be suppressed.",0806.2978v1
+2008-06-25,Morphology and flexibility of graphene and few-layer graphene on various substrates,"We report on detailed microscopy studies of graphene and few-layer-graphene
+produced by mechanical exfoliation on various semi-conducting substrates. We
+demonstrate the possibility to prepare and analyze graphene on (001)-GaAs,
+manganese p-doped (001)-GaAs and InGaAs substrates. The morphology of graphene
+on these substrates was investigated by scanning electron and atomic force
+microscopy and compared to layers on silicon oxide. It was found that graphene
+sheets strongly follow the texture of the sustaining substrates independent on
+doping, polarity or roughness. Furthermore resist residues exist on top of
+graphene after a lithographic step. The obtained results provide the
+opportunity to research the graphene-substrate interactions.",0806.4074v1
+2008-06-30,The superconductivity at 18 K in LiFeAs system,"A new iron arsenide superconducting system LiFeAs was found that crystallizes
+into a tetragonal structure with space group P4/nmm. The superconductivity with
+Tc up to 18 K was observed in the compounds. This simple 111 type layered iron
+arsenide superconductor can be viewed as an analogue of the infinite layer
+structure of copper oxides.",0806.4688v3
+2008-08-07,Ferromagnetism and spin polarized charge carriers in In$_{2}$O$_{3}$ thin films,"We present evidence for spin polarized charge carriers in In$_2$O$_3$ films.
+Both In$_2$O$_3$ and Cr doped In$_2$O$_3$ films exhibit room temperature
+ferromagnetism after vacuum annealing, with a saturation moment of
+approximately 0.5 emu/cm$^3$. We used Point Contact Andreev Reflection
+measurements to directly determine the spin polarization, which was found to be
+approximately 50$\pm$5% for both compositions. These results are consistent
+with suggestions that the ferromagnetism observed in certain oxide
+semiconductors may be carrier mediated.",0808.1123v1
+2008-09-08,Observation of excited states in a p-type GaAs quantum dot,"A quantum dot fabricated by scanning probe oxidation lithography on a p-type,
+C-doped GaAs/AlGaAs heterostructure is investigated by low temperature
+electrical conductance measurements. Clear Coulomb blockade oscillations are
+observed and analyzed in terms of sequential tunneling through the
+single-particle levels of the dot at T_hole = 185 mK. The charging energies as
+large as 2 meV evaluated from Coulomb diamond measurements together with the
+well resolved single-hole excited state lines in the charge stability diagram
+indicate that the dot is operated with a small number of confined particles
+close to the ultimate single-hole regime.",0809.1362v1
+2008-09-17,Polaron Coherence as Origin of the Pseudogap Phase in High Temperature Superconducting Cuprates,"Within a two component approach to high Tc copper oxides including polaronic
+couplings, we identify the pseudogap phase as the onset of polaron ordering.
+This ordering persists in the superconducting phase. A huge isotope effect on
+the pseudogap onset temperature is predicted and in agreement with experimental
+data. The anomalous temperature dependence of the mean square copper oxygen ion
+displacement observed above, at and below Tc stems from an s-wave
+superconducting component of the order parameter, whereas a pure d-wave order
+parameter alone can be excluded.",0809.2881v1
+2008-09-22,Collision of a sphere onto a wall coated with a liquid film,"Particle-particle and particle-wall collisions occur in many natural and
+industrial applications such as sedimentation, agglomeration, and granular
+flows. To accurately predict the behavior of particulate flows, fundamental
+knowledge of the mechanisms of a single collision is required. In this fluid
+dynamics video, particle-wall collisions onto a wall coated with 1.5%
+poly(ethylene-oxide) (PEO) (viscoelastic liquid) and 80% Glycerol and water
+(Newtonian liquid) are shown.",0809.3770v1
+2008-09-24,Optically induced electrokinetic patterning and manipulation of particles,"This fluid dynamics video showcases how optically induced electrokinetic
+forces can be used to drive three-dimensional micro-vortices. The strong
+microfluidic vortices are used constructively in conjunction with other
+electrokinetic forces to dynamically and rapidly aggregate particle groups.
+Particle manipulation is achieved on the surface of a parallel-plate
+gold/indium tin oxide (ITO) electrode that is illuminated with near-infrared
+(1064 nm) optical patterns and biased with a low frequency ($<$ 100 kHz)
+alternating current (AC) signal. The fluid dynamics video shows how
+electrokinetically driven flows in the microdomain can be used for non-invasive
+particle manipulation.",0809.4083v2
+2008-09-26,DNA adsorption at liquid/solid interfaces,"DNA adsorption on solid or liquid surfaces is a topic of broad fundamental
+and applied interest. Here we study by x-ray reflectivity the adsorption of
+monodisperse double-stranded DNA molecules a positively-charged surface,
+obtained through chemical grafting of a homogeneous organicmonomolecular layer
+of N-(2-aminoethyl) dodecanamide on an oxide-free monocrystalline Si(111)
+wafer. The adsorbed dsDNA is found to embed into the soft monolayer which is
+deformed in the process. The surface coverage is very high and this adsorbed
+layer is expected to display 2D nematic ordering.",0809.4639v1
+2008-10-14,Successive Phase Transitions in Na_{0.5}CoO_{2} based on the Triangular Lattice d-p Model,"We investigate the electronic states of the CoO_2 plane in the layered cobalt
+oxides Na_{0.5}CoO_{2} using the realistic 11 band d-p model on a
+two-dimensional triangular lattice. Effects of the Coulomb interaction on a Co
+site: the intra- and inter-orbital direct terms U and U', the exchange coupling
+J and the pair-transfer J', are treated within the Hartree-Fock approximation.
+It is found that the metallic antiferromagnetism takes place below T_{c1} and,
+in addition, the orbital order accompanied by the small charge order takes
+place below T_{c2} (< T_{c1}) where the system becomes insulator. The obtained
+results are consistent with the successive phase transitions observed in
+Na_{0.5}CoO_{2}.",0810.2380v1
+2008-10-19,Spin-triplet f-wave pairing due to three-site cyclic-exchange ferromagnetic interactions,"Ferromagnetiam and superconductivity in a two-dimensional triangular-lattice
+Hubbard model are studied using the density-matrix renormalization group
+method. We propose a mechanism of the {\it f}-wave spin-triplet pairing derived
+from the three-site cyclic-exchange ferromagnetic interactions. We point out
+that a triangular network of hopping integrals, which is required for the
+three-site cyclic hopping processes, is contained in the (possibly)
+spin-triplet superconducting systems, such as Bechgaard salts (TMTSF)$_2$X,
+cobalt oxide Na$_{0.35}$CoO$_2$$\cdot$1.3H$_2$O, and layered perovskite
+Sr$_2$RuO$_4$.",0810.3387v1
+2008-10-20,Modulation Doping of a Mott Quantum Well by a Proximate Polar Discontinuity,"We present evidence for hole injection into LaAlO3/LaVO3/LaAlO3 quantum wells
+near a polar surface of LaAlO3 (001). As the surface is brought in proximity to
+the LaVO3 layer, an exponential drop in resistance and a decreasing positive
+Seebeck coefficient is observed below a characteristic coupling length of 10-15
+unit cells. We attribute this behavior to a crossover from an atomic
+reconstruction of the AlO2-terminated LaAlO3 surface to an electronic
+reconstruction of the vanadium valence. These results suggest a general
+approach to tunable hole-doping in oxide thin film heterostructures.",0810.3469v1
+2008-10-21,Generalizing the Cooper-Pair Instability to Doped Mott Insulators,"Copper oxides become superconductors rapidly upon doping with electron holes,
+suggesting a fundamental pairing instability. The Cooper mechanism explains
+normal superconductivity as an instability of a fermi-liquid state, but
+high-temperature superconductors derive from a Mott-insulator normal state, not
+a fermi liquid. We show that precocity to pair condensation with doping is a
+natural property of competing antiferromagnetism and d-wave superconductivity
+on a singly-occupied lattice, thus generalizing the Cooper instability to doped
+Mott insulators, with significant implications for the high-temperature
+superconducting mechanism.",0810.3862v1
+2008-10-24,High-Mobility Few-Layer Graphene Field Effect Transistors Fabricated on Epitaxial Ferroelectric Gate Oxides,"The carrier mobility \mu of few-layer graphene (FLG) field-effect transistors
+increases ten-fold when the SiO_2 substrate is replaced by single-crystal
+epitaxial Pb(Zr_0.2Ti_0.8)O_3 (PZT). In the electron-only regime of the FLG,
+\mu reaches 7x10^4 cm^2/Vs at 300K for n = 2.4x10^12/cm^2, 70% of the intrinsic
+limit set by longitudinal acoustic (LA) phonons; it increases to 1.4x10^5
+cm^2/Vs at low temperature. The temperature-dependent resistivity \rho(T)
+reveals a clear signature of LA phonon scattering, yielding a deformation
+potential D = 7.8+/-0.5 eV.",0810.4466v1
+2008-10-27,Emergence of Antiferromagnetic Correlation in LiTi2-xVxO4 via 7Li NMR,"We report 7Li NMR studies of V-substitution effects on spinel oxide
+superconductor LiTi2O4 (Tc = 13.4 K). In LiTi2-xVxO4 (x = 0-0.4), the V
+substitution for the Ti site suppressed the relative volume fraction of
+superconductivity faster than Tc. From the observation of fairly homogeneous
+enhancement in a 7Li nuclear spin-lattice relaxation rate, we conclude that the
+V substitution changes electron correlation effects through electron carrier
+doping from quarter electron filling 3d0.5 to 3d1.5 and then the
+antiferromagnetic correlation emerges.",0810.4865v1
+2008-10-29,High-Mobility Few-Layer Graphene Field Effect Transistors Fabricated on Epitaxial Ferroelectric Gate Oxides (Supplementary Information),"Supplementary Information to arXiv:0810.4466: 1. Characterizations of
+Pb(Zr_0.2Ti_0.8)O_3 (PZT) films. 2. Substrate preparation before the
+exfoliation of graphene. 3. The band structure of FLG. 4. Dielectric constant
+measurements of PZT. 5. rho(V_g) and R_H(V_g) fitting inside the band overlap
+regime. 6. The deformation potential of longitudinal acoustic (LA) phonons in
+graphene. 7. Resistivity and Hall measurements of a SiO_2-gated FLG.",0810.5339v1
+2008-10-30,Removal of Pollutants by Atmospheric Non Thermal Plasmas,"Results on the application of non thermal plasmas in two environmentally
+important fields: oxidative removal of VOC and NOx in excess of oxygen were
+presented. The synergetic application of a plasma-catalytic treatment of NOx in
+excess of oxygen is also described.",0810.5432v1
+2008-11-05,Giant electro-thermal conductivity and spin-phonon coupling in an antiferromagnetic oxide,"The application of weak electric fields (<~ 100 V/cm) is found to
+dramatically enhance the lattice thermal conductivity of the antiferromagnetic
+(AF) insulator CaMnO(3) over a broad range of temperature about the Neel
+ordering point (125 K). The effect is coincident with field-induced de-trapping
+of bound electrons, suggesting that phonon scattering associated with short-
+and long-ranged AF order is suppressed in the presence of the mobilized charge.
+This interplay between bound charge and spin-phonon coupling might allow for
+the reversible control of spin fluctuations using weak external fields.",0811.0744v1
+2008-11-07,Strong Anomalous Optical Dispersion of Graphene: Complex Refractive Index Measured by Picometrology,"We apply spinning-disc picometrology to measure the complex refractive index
+of graphene on thermal oxide on silicon. The refractive index varies from n =
+2.4-1.0i at 532 nm to n = 3.0-1.4i at 633 nm at room temperature. The
+dispersion is five times stronger than bulk graphite (2.67-1.34i to 2.73-1.42i
+from 532 nm to 633 nm).",0811.1210v1
+2008-11-10,"Low-dimensional NbO structures on the Nb(110) surface: scanning tunneling microscopy, electron spectroscopy and diffraction","X-ray photoelectron spectroscopy and diffraction (XPS, XPD) and scanning
+tunneling microscopy (STM) have been used for study of NbOx-structures on the
+Nb(110) surface. It is shown that niobium atoms are ordered to form a
+two-dimensional superstructure with equidistant spacing between the chains of
+niobium atoms. Chemical shifts of Nb3d- and O1s-levels demonstrate that the
+oxide layer corresponds to niobium monoxide NbO and the most part of oxygen in
+chemisorbed state is localized on the surface. A model of quasi-ordered
+structure of NbO on the Nb(110) surface is proposed.",0811.1424v1
+2008-11-25,Etching-dependent reproducible memory switching in vertical SiO2 structures,"Vertical structures of SiO$_{2}$ sandwiched between a top tungsten electrode
+and conducting non-metal substrate were fabricated by dry and wet etching
+methods. Both structures exhibit similar voltage-controlled memory behaviors,
+in which short voltage pulses (1 $\mu$s) can switch the devices between high-
+and low-impedance states. Through the comparison of current-voltage
+characteristics in structures made by different methods, filamentary conduction
+at the etched oxide edges is most consistent with the results, providing
+insights into similar behaviors in metal/SiO/metal systems. High ON/OFF ratios
+of over 10$^{4}$ were demonstrated.",0811.4099v1
+2008-12-08,Metal-Insulator phase diagram and orbital selectivity in 3-orbital models with rotationally invariant Hund coupling,"A three band model containing the essential physics of transition metal
+oxides with partially filled t_2g shells is solved in the single-site dynamical
+mean field approximation, using the full rotationally invariant Slater-Kanamori
+interactions. We compute the metal-Mott insulator phase diagram in the space of
+chemical potential and interaction strength, determine the response of the
+different phases to perturbations which break the orbital symmetry, and
+establish the regimes in which an orbital selective Mott phase occurs. The
+results are compared to data on titanates, ruthenates, vanadates and C_60.",0812.1520v1
+2008-12-12,Autocatalytic MBE growth of GaAs nanowires on oxidized Si(100),"GaAs nanowires were grown by molecular beam epitaxy on Si(100) substrates
+covered with 5 nm SiO2. The growth was performed with As4 at low, close to
+stoichiometric, As4/Ga flux ratio, using Ga nanodroplets as catalyst. The
+nanowires are found to be in epitaxial relation to the Si substrate due to
+contact via pinholes through the SiO2 layer. The nanowires are up to 15
+micrometers long and have diameters of about 100 nm, the catalyzing Ga
+nanodroplets are observed at their tops.",0812.2453v1
+2008-12-15,First-Principles Study on Leakage Current through Si/SiO$_2$ Interface,"The relationship between the presence of defects at the stacking structure of
+the Si/SiO$_2$ interface and leakage current is theoretically studied by
+first-principles calculation. I found that the leakage current through the
+interface with dangling bonds is 530 times larger than that without any
+defects, which is expected to lead to dielectric breakdown. The direction of
+the dangling bonds is closely related to the performance of the oxide as an
+insulator. In addition, it is proved that the termination of the dangling bonds
+by hydrogen atoms is effective for reducing the leakage current.",0812.2773v2
+2008-12-22,Green's function of fully anharmonic lattice vibration,"Motivated by the discovery of superconductivity in beta-pyrochlore oxides, we
+study property of rattling motion coupled with conduction electrons. We derive
+the general expression of the Green's function of fully anharmonic lattice
+vibration within the accuracy of the second order perturbation of electron-ion
+interaction by introducing self-energy, vertex-correction, and normalization
+factor for each transition. Using the expression, we discuss the characteristic
+properties of the spectral function in the entire range from weakly anharmonic
+potential to double-well case, and calculate NMR relaxation rate due to the two
+phonon Raman process.",0812.4100v1
+2009-01-07,Phase-transition driven memristive system,"Memristors are passive circuit elements which behave as resistors with
+memory. The recent experimental realization of a memristor has triggered
+interest in this concept and its possible applications. Here, we demonstrate
+memristive response in a thin film of Vanadium Dioxide. This behavior is driven
+by the insulator-to-metal phase transition typical of this oxide. We discuss
+several potential applications of our device, including high density
+information storage. Most importantly, our results demonstrate the potential
+for a new realization of memristive systems based on phase transition
+phenomena.",0901.0899v2
+2009-01-19,A new temperature scale T* in lead-based relaxor systems,"Via a combination of various experimental and theoretical techniques, a
+peculiar, identical temperature scale T* is found to exist in all complex
+lead-based relaxor ferroelectrics. T* corresponds to a nanoscale phase
+transition due to random fields. Interestingly, T* also exists in other oxides
+with extraordinary properties, such as giant magnetoresistivity or
+superconductivity. By analogy with such latter systems, the giant
+piezoelectricity related to relaxors might originate from proximity competing
+states effect.",0901.2604v1
+2009-02-11,Screening of electromagnetic field fluctuations by s--wave and d--wave superconductors,"We investigate theoretically the shielding of the electromagnetic field
+fluctuations by s-wave and d-wave superconductors within the framework of
+macroscopic quantum electrodynamics. The spin flip lifetime is evaluated above
+a niobium and a bismuth strontium calcium copper oxide (BSCCO) surface, and the
+screening effect is studied as a function of the thickness of the
+superconducting layer. Further, we study the different temperature dependence
+of the atomic spin relaxation above the two superconductors.",0902.1981v2
+2009-03-13,Optical Trajectory of the Insulator-to-metal Transition of Ultra-thin Gold Films,"We apply interferometric picometrology to measure the complex refractive
+index and dielectric properties of ultra-thin gold films as a continuous
+function of thickness from 0.2 nm to 10 nm deposited on thermal oxide on
+silicon. Three distinct regimes are found for the dielectric constant
+trajectory in the complex plane. The first regime shows a circular trajectory
+predicted by the Drude equation tracing the gold bulk-to-thin film transition.
+The second and third regimes are manifested as metal clusters range from large
+to small size and sparse coverage. The entire atom-to-bulk transition of gold
+is revealed from the optical perspective.",0903.2492v1
+2009-03-24,Band structure of new layered 17 K superconductor Sr4Sc2Fe2P2O6 in comparison with hypothetical Sr4Sc2Fe2As2O6,"The results of the ab initio FLAPW-GGA calculations of the band structure of
+the newly synthesized tetragonal (space group P4/nmm) layered iron
+phosphide-oxide: 17K superconductor Sr4Sc2Fe2P2O6 are presented. For
+Sr4Sc2Fe2P2O6 the optimized structural data, the energy bands, total and
+partial densities of states, Fermi surface topology, low-temperature electron
+specific heat and molar Pauli paramagnetic susceptibility have been determined
+and discussed in comparison with hypothetical isostructural iron arsenide-oxide
+phase Sr4Sc2Fe2As2O6 and related layered FeAs and FeP superconductors.",0903.4038v1
+2009-03-25,"Universal Non-Landau, Self-Organized, Lattice Disordering Percolative Dopant Network Sub-Tc Phase Transitions in Ceramic Superconductors","Ceramic superconductors (cuprates, pnictides, ...) exhibit universal features
+in both Tcmax and in their planar lattice disordering measured by EXAFS, as
+reflected by three phase transitions. The two highest temperature transitions
+are known to be associated with formation of pseudogaps and superconductive
+gaps, with corresponding Landau order parameters, but no new gap is associated
+with the third transition below Tc. It is argued that the third transition is a
+dopant glass transition, which is remarkably similar to transitions previously
+observed in chalcogenide and oxide alloy network glasses (like window glass).",0903.4376v1
+2009-04-01,Electronic structure of Ti-doped Sr4Sc2Fe2As2O6,"First principle FLAPW-GGA calculations have been performed with the purpose
+to understand the electronic properties for the newly synthesized tetragonal
+(space group P4/nmm) layered iron arsenide-oxide: Sr4Sc2Fe2As2O6 doped with
+titanium. The total and partial densities of states, low-temperature electron
+specific heat and molar Pauli paramagnetic susceptibility have been obtained
+and discussed for Sr4ScTiFe2As2O6 in comparison with parent phase
+Sr4Sc2Fe2As2O6.
+  Our results show that the insertion of Ti into Sc sublattice of iron
+arsenide-oxide phase Sr4Sc2Fe2As2O6 leads to principal change of its electronic
+structure; in result the insulating so-called ""charge reservoirs', i.e.
+perovskite-based [Sr4Sc2O6] blocks became conducting. This situation differs
+essentially from the known picture for all others Fe-As superconductors where
+the conducting [Fe2As2] blocks are separated by isolating blocks.",0904.0117v1
+2009-04-21,Molecular modeling and simulation of thermophysical properties: Application to pure substances and mixtures,"At the Institute for Thermodynamics and Thermal Process Engineering (ITT)
+about 100 molecular models for pure substances have been developed so far.
+These models reproduce vapor pressure, saturated liquid density, and enthalpy
+of vaporization with a technical accuracy of less than 5%, less than 1%, and
+less than 5% deviation compared to experimental data, respectively.
+  Simulation results are outlined for the pure substances ethylene oxide and
+ammonia, demonstrating the outstanding predictive power of the applied methods.
+Secondly, nucleation processes are discussed. Underlying effects on are studied
+on the molecular level.",0904.3191v1
+2009-04-27,Production d'hydrogène par oxydation catalytique partielle du méthane Etude du mécanisme réactionnel,"The partial oxidation of methane was investigated using a self-stirred
+reactor under a wide range of operating conditions. The recation mechanism was
+determined by comparing ecperimental results with the results of simulations
+made using the Chemkin-Surface software. The proposed mechanism includes 444
+homogeneous reactions and 33 surface reactions.",0904.4138v1
+2009-05-02,Quantum fluctuation and geometrical frustration effects on electric polarization,"We examine theoretically a possibility of ferroelectricity caused by
+electronic charge order without inversion symmetry, motivated by layered iron
+oxides. Quantum electronic models in a paired-triangular lattice are analyzed
+by utilizing the variational Monte Carlo simulation. Our calculation
+demonstrates that combined effects of electron transfer between the layers,
+corresponding to quantum fluctuation between the potential minima, and
+geometrical frustration promote appearance of an electric polarization. Present
+results are in contrast to the conventional manner of quantum fluctuation in
+ferroelectricity.",0905.0182v1
+2009-05-05,Spectroscopic studies on nanocomposites obtained by functionalization of carbon nanotubes with conducting polymers,"Vibrational properties of composites based on single-walled carbon nanotubes
+(SWNTs) and conducting polymers of the type polyaniline (PANI) and poly
+(3,4-ethylene dioxythiophene) (PEDOT) are reported. For PANI-functionalized
+SWNTs, the intensity increase of the Raman band at 178 cm-1, associated with
+radial breathing modes of SWNTs bundles, indicates an additional roping of
+nanotubes due to the presence of the polymer. The interaction of this composite
+with NH4OH solution involves an internal redox reaction between PANI and SWNTs.
+Thus, the polymer chain undergoes a transition from the semi-oxidized state
+into a reduced one. The functionalization of SWNT side walls with PEDOT is
+invoked as well.",0905.0533v1
+2009-05-05,"A new material for hydrogen storage, ScAl0.8Mg0.2","A novel aluminium rich alloy for hydrogen storage has been discovered,
+ScAl0.8Mg0.2, which has superior properties regarding hydrogen storage
+capacity, kinetics and stability towards air oxidation in comparison to
+hydrogen absorption in state-of-the-art intermetallic compounds. Detailed
+analysis of the hydrogen absorption in ScAl0.8Mg0.2 has been performed using in
+situ synchrotron radiation powder X-ray diffraction, neutron powder diffraction
+and quantum mechanical calculations. The results from calculations and
+experiments are in good agreement with each other.",0905.0630v2
+2009-05-18,NO2 and Humidity Sensing Characteristics of Few-layer Graphene,"Sensing characteristics of few-layer graphenes for NO2 and humidity have been
+investigated with graphene samples prepared by the thermal exfoliation of
+graphitic oxide (EG), conversion of nanodiamond (DG) and arc-discharge of
+graphite in hydrogen (HG). The sensitivity for NO2 is found to be highest with
+DG. Nitrogen-doped HG (n-type) shows increased sensitivity for NO2 compared to
+pure HG. The highest sensitivity for humidity is observed with HG. The sensing
+characteristics of graphene have been examined for different aliphatic alcohols
+and the sensitivity is found to vary with the chain length and branching.",0905.2852v1
+2009-06-30,Identification of vacancy defects in a thin film perovskite oxide,"Vacancy defects in thin film laser ablated SrTiO3 on SrTiO3 were identified
+using variable energy positron annihilation lifetime measurements. Strontium
+vacancy related defects were the dominant positron traps and, apart from in the
+top ~ 50 nm, were found to be uniformly distributed. The surface layer showed
+an increase in annihilation from larger open-volume defects, large vacancy
+clusters or nanovoids.",0906.5558v1
+2009-07-22,Partial order in a frustrated Potts model,"We investigate a 4-state ferromagnetic Potts model with a special type of
+geometrical frustration on a three dimensional diamond lattice by means of
+Wang-Landau Monte Carlo simulation motivated by a peculiar structural phase
+transition found in $\beta$-pyrochlore oxide KOs$_2$O$_6$. We find that this
+model undergoes unconventional first-order phase transition; half of the spins
+in the system order in a two dimensional hexagonal-sheet-like structure, while
+the remaining half stay disordered. The ordered sheets and the disordered
+sheets stack one after another. We obtain a fairly large residual entropy at $T
+= 0$ which originates from the disordered sheets.",0907.3812v1
+2009-08-12,Edge-carboxylated Carbon Nanoflakes from Nitric Acid Oxidised Arc-discharge Material,"Carbon Nanoflakes (CNFs) with average diameters of about 30 nm have been
+prepared and isolated in bulk quantities by a single-step oxidation procedure
+using single-wall carbon nanotube arc-discharge material and nitric acid. The
+CNFs are predominately single, graphenic sheets containing a small number of
+internal defects. The edges are decorated with primarily carboxylic acid groups
+which allow facile chemical functionalisation and cross-linking of the
+fragments using multivalent cations.",0908.1740v1
+2009-08-12,Hierarchy of Electronic Properties of Chemically Derived and Pristine Graphene Probed by Microwave Imaging,"Local electrical imaging using microwave impedance microscope is performed on
+graphene in different modalities, yielding a rich hierarchy of the local
+conductivity. The low-conductivity graphite oxide and its derivatives show
+significant electronic inhomogeneity. For the conductive chemical graphene, the
+residual defects lead to a systematic reduction of the microwave signals. In
+contrast, the signals on pristine graphene agree well with a lumped-element
+circuit model. The local impedance information can also be used to verify the
+electrical contact between overlapped graphene pieces.",0908.1778v1
+2009-09-23,First-Principles Approach to Heat and Mass Transfer Effects in Model Catalyst Studies,"We assess heat and mass transfer limitations in in situ studies of model
+catalysts with a first-principles based multiscale modeling approach that
+integrates a detailed description of the surface reaction chemistry and the
+macro-scale flow structures. Using the CO oxidation at RuO2(110) as a
+prototypical example we demonstrate that factors like a suppressed heat
+conduction at the backside of the thin single-crystal, and the build-up of a
+product boundary layer above the flat-faced surface play a significant role.",0909.4261v1
+2009-10-16,Checkerboard superconducting order and antinodal Bogoliubov quasiparticle interference,"Numerical study of momentum-dependent gap function is presented to make clear
+the origin of superconductivity in copper oxides. We claim that antinodal
+region with pronounced nesting feature of the Fermi contour gives rise to
+superconducting pairing with large momentum under screened Coulomb repulsion.
+Such a pairing results in both spatial checkerboard pattern of the
+superconducting state below Tc and a gapped state of incoherent pairs in a
+broad temperature range above Tc. We explain the momentum dependence of the
+coherent spectral weight detected in angle-resolved photoemission spectroscopy
+and predict antinodal Bogoliubov quasiparticle interference other than observed
+in the nodal region.",0910.3172v1
+2009-11-07,Lifetime positron annihilation spectroscopy and photo-inactivated bacteria,"Combined positron and visible light irradiations in the photodynamical
+therapy (PDT) applications are analyzed. Objectives and goals of PDT are
+killing or irreversible oxidative damage of pathogenic cells, or rather their
+cell walls, cell membranes, peptides, and nucleic acids by photo-activated
+oxygen of photosentizer injected into the target cell during light irradiation.
+In this paper, the arguments for involving of lifetime positron annihilation
+spectroscopy to control of photodamaging cells in the course of the PDT
+procedure are given on the examples of gram-positive and gram-negative bacteria
+basing on a brief survey of the literature.",0911.1389v3
+2009-11-09,Luminescent Ions in Silica-Based Optical Fibers,"We present some of our research activities dedicated to doped silica-based
+optical fibers, aiming at understanding the spectral properties of luminescent
+ions, such as rare-earth and transition metal elements. The influence of the
+local environment on dopants is extensively studied: energy transfer mechanisms
+between rare-earth ions, control of the valence state of chromium ions, effect
+of the local phonon energy on thulium ions emission efficiency, and broadening
+of erbium ions emission induced by oxide nanoparticles. Knowledge of these
+effects is essential for photonics applications.",0911.1683v1
+2009-11-27,Melting slope of MgO from molecular dynamics and density functional theory,"We combine density functional theory (DFT) with molecular dynamics
+simulations based on an accurate atomistic force field to calculate the
+pressure derivative of the melting temperature of magnesium oxide at ambient
+pressure - a quantity for which a serious disagreement between theory and
+experiment has existed for almost 15 years. We find reasonable agreement with
+previous DFT results and with a very recent experimental determination of the
+slope. We pay particular attention to areas of possible weakness in theoretical
+calculations and conclude that the long-standing discrepancy with experiment
+could only be explained by a dramatic failure of existing density functionals
+or by flaws in the original experiment.",0911.5309v1
+2010-01-01,Dipole trap model for the metallic state in gated silicon-inversion layers,"In order to investigate the metallic state in high-mobility Si-MOS
+structures, we have further developed and precised the dipole trap model which
+was originally proposed by B.L. Altshuler and D.L. Maslov [Phys. Rev. Lett.\
+82, 145 (1999)]. Our additional numerical treatment enables us to drop several
+approximations and to introduce a limited spatial depth of the trap states
+inside the oxide as well as to include a distribution of trap energies. It
+turns out that a pronounced metallic state can be caused by such trap states at
+appropriate energies whose behavior is in good agreement with experimental
+observations.",1001.0205v1
+2010-02-01,The Novelty of Syntheses & Varied Applications of ZnO nano systems,"Controlled synthesis of nano materials is critical for the development of
+nanotechnologies concerned with respect to shape and size. Especially, ZnO
+nanosystems, such as wires, belts, needles and films can be easily formed by
+either physical or chemical approaches such as, Chemical Vapour Deposition,
+Metal Organic Chemical Vapour Deposition, Pulsed Laser Deposition, Molecular
+Beam Epitaxy, Sol Gel process, Thermal Annealing method and Solvothermal
+Oxidation. ZnO has polar surfaces that help in the formation of a wide range of
+nanostructures such as needles,films rings, springs, bows and helices",1002.0199v1
+2010-02-18,Hysteresis Switching Loops in Ag-manganite memristive interfaces,"Multilevel resistance states in silver-manganite interfaces are studied both
+experimentally and through a realistic model that includes as a main ingredient
+the oxygen vacancies diffusion under applied electric fields. The switching
+threshold and amplitude studied through Hysteresis Switching Loops are found to
+depend critically on the initial state. The associated vacancy profiles further
+unveil the prominent role of the effective electric field acting at the
+interfaces. While experimental results validate main assumptions of the model,
+the simulations allow to disentangle the microscopic mechanisms behind the
+resistive switching in metal-transition metal oxide interfaces.",1002.3593v1
+2010-04-04,Simulation of ion track ranges in uranium oxide,"Direct comparisons between statistically sound simulations of ion-tracks and
+published experimental measurements of range densities of iodine implants in
+uranium dioxide have been made with implant energies in the range of 100-800
+keV. Our simulations are conducted with REED-MD (Rare Event Enhanced
+Domain-following Molecular Dynamics) in order to account for the materials
+structure in both single crystalline and polycrystalline experimental samples.
+We find near-perfect agreement between REED-MD results and experiments for
+polycrystalline target materials.",1004.0490v1
+2010-04-01,Lattice coupling and Franck-Condon effects in K-edge resonant inelastic X-ray scattering,"We discuss recent Cu K-edge resonant inelastic scattering (RIXS) results for
+CuB2O4, a model system consisting of electronically-isolated CuO4 plaquettes,
+which exhibits anomalies in the incident photon energy dependence that are not
+captured by electron-only models. We show that these anomalous features can be
+qualitatively described by extending the electron-only considerations to
+include the lattice degrees of freedom. Our findings have important general
+implications for the interpretation of K-edge RIXS results for electronically
+higher-dimensional transition metal oxides.",1004.0859v1
+2010-04-26,Andreev reflection in ferrimagnetic CoFe2O4/SrRuO3 spin filters,"We have performed point contact spectroscopy measurements on a sample
+constituted by a metallic ferromagnetic oxide (SrRuO_3) bottom electrode and a
+tunnel ferrimagnetic (CoFe_2O_4) barrier. Andreev reflection is observed across
+the tunnel barrier. From the comparison of Andreev reflection in SrRuO3 and
+across the CoFe_2O_4 barrier we infer that the ferrimagnetic barrier has a spin
+filter efficiency not larger than +13%. The observation of a moderate and
+positive spin filtering is discussed in the context of the microstructure of
+the barriers and symmetry-related spin filtering effects.",1004.4631v1
+2010-06-08,Dramatic Mobility Enhancements in Doped SrTiO3 Thin Films by Defect Management,"We report bulk-quality n-type SrTiO3 (n-SrTiO3) thin films fabricated by
+pulsed laser deposition, with electron mobility as high as 6600 cm2 V-1 s-1 at
+2 K and carrier density as low as 2.0 x 10^18cm-3 (~ 0.02 at. %), far exceeding
+previous pulsed laser deposition films. This result stems from precise
+strontium and oxygen vacancy defect chemistry management, providing a general
+approach for defect control in complex oxide heteroepitaxy.",1006.1564v1
+2010-06-25,Paramagnetic centers in graphene nanoribbons prepared from longitudinal unzipping of carbon nanotubes,"Electron spin resonance (ESR) investigation of graphene nanoribbons (GNRs)
+prepared through longitudinal unzipping of multiwalled carbon nanotubes
+(MWCNTs) indicates the presence of C-related dangling bond centers, exhibiting
+paramagnetic features. ESR signal broadening from pristine or oxidized graphene
+nanoribbons (OGNRs) is explained in terms of unresolved hyperfine structure,
+and in the case of reduced GNRs (RGNRs), the broadening of ESR signal can be
+due to enhancement in conductivity upon reduction. The spin dynamics observed
+from ESR linewidth-temperature data reflect a variable range hopping (VRH)
+mechanism through localized states, consistent with resistance-temperature
+data.",1006.4942v1
+2010-07-13,Size and Defect related Broadening of Photoluminescence Spectra in ZnO:Si Nanocomposite Films,"Nanocomposite films of Zinc Oxide and Silicon were grown by thermal
+evaporation technique using varying ratios of ZnO:Si in the starting material.
+Analysis reveal the role of ZnO and amorphous silicon interface in contributing
+to relatively less common blue photoluminescence emissions (at $\sim$ 400 and
+470nm). These blue peaks are observed along with the emissions resulting from
+band edge transition (370nm) and those related to defects (522nm) of ZnO.
+Careful analysis shows that along with the grain size of ZnO, a suitable
+compositional ratio (of ZnO to silicon) is critical for the coexistence of all
+the four peaks. Proper selection of conditions can give comparable
+photoluminescence peak intensities leading to broad-band emission.",1007.2142v1
+2010-08-18,Diminished Short Channel Effects in Nanoscale Double-Gate Silicon-On-Insulator Metal-Oxide- Semiconductor Field-Effect-Transistors due to Induced Back-Gate Step Potential,"In this letter we discuss how the short channel behavior in sub 100 nm
+channel range can be improved by inducing a step surface potential profile at
+the back gate of an asymmetrical double gate (DG) Silicon-On-Insulator (SOI)
+Metal-Oxide-Semiconductor Field-Effect- Transistor (MOSFET) in which the front
+gate consists of two materials with different work functions.",1008.3016v1
+2010-08-28,Resonant Inelastic X-ray Scattering on Spin-Orbit Coupled Insulating Iridates,"We determine how the elementary excitations of iridium-oxide materials, which
+are dominated by a strong relativistic spin-orbit coupling, appear in Resonant
+Inelastic X-ray Scattering (RIXS). Whereas the RIXS spectral weight at the L2
+x-ray edge vanishes, we find it to be strong at the L3-edge. Applying this to
+Sr2IrO4, we observe that RIXS, besides being sensitive to local doublet to
+quartet transitions, meticulously maps out the strongly dispersive delocalized
+excitations of the low-lying spin-orbit doublets.",1008.4862v1
+2010-08-31,Chemisorption of a molecular oxygen on the UN (001) surface: ab initio calculations,"The results of DFT GGA calculations on oxygen molecules adsorbed upon the
+(001) surface of uranium mononitride (UN) are presented and discussed. We
+demonstrate that O2 molecules oriented parallel to the substrate can dissociate
+either (i) spontaneously when the molecular center lies above the surface
+hollow site or atop N ion, (ii) with the activation barrier when a molecule
+sits atop the surface U ion. This explains fast UN oxidation in air.",1008.5323v1
+2010-09-03,Superconducting junctions from non-superconducting doped CuO$_2$ layers,"The theoretical approach proposed recently for description of redistribution
+of electronic charge in multilayered selectively doped systems is modified for
+a system with finite number of layers. A special attention is payed to the case
+of a finite heterostructure made of copper-oxide layers which are all
+non-superconducting (including non-conducting) because of doping levels being
+beyond the well-known characteristic interval for superconductivity. Specific
+finite structures and doping configurations are proposed to obtain atomically
+thin superconducting heterojunctions of different compositions.",1009.0740v4
+2010-09-07,"Composite-Fermion Theory for Pseudogap, Fermi Arc, Hole Pocket, and Non-Fermi-Liquid of Underdoped Cuprate Superconductors","We propose that an extension of the exciton concept to doped Mott insulators
+offers a fruitful insight into challenging issues of the copper oxide
+superconductors. In our extension, new fermionic excitations called cofermions
+emerge in conjunction to generalized excitons. The cofermions hybridize with
+conventional quasiparticles. Then a hybridization gap opens, and is identified
+as the pseudogap observed in the underdoped cuprates. The resultant
+Fermi-surface reconstruction naturally explains a number of unusual properties
+of the underdoped cuprates, such as the Fermi arc and/or pocket formation.",1009.1197v1
+2010-09-14,Highly Tunable Hybrid Quantum Dots with Charge Detection,"In order to employ solid state quantum dots as qubits, both a high degree of
+control over the confinement potential as well as sensitive charge detection
+are essential. We demonstrate that by combining local anodic oxidation with
+local Schottky-gates, these criteria are nicely fulfilled in the resulting
+hybrid device. To this end, a quantum dot with adjacent charge detector is
+defined. After tuning the quantum dot to contain only a single electron, we are
+able to observe the charge detector signal of the quantum dot state for a wide
+range of tunnel couplings.",1009.2578v1
+2010-10-27,Molecular dynamics simulations of oxide memory resistors (memristors),"Reversible bipolar nano-switches that can be set and read electronically in a
+solid-state two-terminal device are very promising for applications. We have
+performed molecular-dynamics simulations that mimic systems with oxygen
+vacancies interacting via realistic potentials and driven by an external bias
+voltage. The competing short- and long-range interactions among charged mobile
+vacancies lead to density fluctuations and short-range ordering, while
+illustrating some aspects of observed experimental behavior, such as memristor
+polarity inversion.",1010.5656v1
+2010-11-24,Electronic properties of new low-temperature superconductors: 3.3K (Ni2P2)(Sr4Sc2O6) and 2.7K (Ni2As2)(Sr4Sc2O6) from first principles,"Based on first-principle FLAPW-GGA calculations, we have investigated
+structural and electronic properties of the recently synthesized tetragonal
+(space group P4/nmm) nickel-based pnictide oxide superconductors: 3.3K
+(Ni2P2)(Sr4Sc2O6) and 2.7K (Ni2As2)(Sr4Sc2O6). Optimized structural data,
+electronic bands, total and partial densities of states, and Fermi surface
+topology have been obtained and discussed in comparison with available
+experiments and with their Fe-based (Fe2P2)(Sr4Sc2O6) and (Fe2As2)(Sr4Sc2O6)
+analogs.",1011.5323v1
+2010-11-26,Maximally Supersymmetric Yang-Mills in five dimensions in light-cone superspace,"We formulate maximally supersymmetric Yang-Mills theory in five dimensions in
+light-cone superspace. The light-cone Hamiltonian is of the quadratic form and
+the theory can be understood as an oxidation of the N=4 Super Yang-Mills Theory
+in four dimensions. We specifically study three-point counterterms and show how
+these counterterms vanish on-shell. This study is a preliminary to set up the
+technique in order to study possible four-point counterterms.",1011.5817v2
+2010-12-11,First-principles modeling of electrostatically doped perovskite systems,"Macroscopically, confined electron gases at polar oxide interfaces are
+rationalized within the simple ""polar catastrophe"" model. At the microscopic
+level, however, many other effects such as electric fields, structural
+distortions and quantum-mechanical interactions enter into play. Here we show
+how to bridge the gap between these two length scales, by combining the
+accuracy of first-principles methods with the conceptual simplicity of model
+Hamiltonian approaches. To demonstrate our strategy, we address the equilibrium
+distribution of the compensating free carriers at polar LaAlO3/SrTiO3
+interfaces. Remarkably, a model including only calculated bulk properties of
+SrTiO3 and no adjustable parameters accurately reproduces our full
+first-principles results. Our strategy provides a unified description of charge
+compensation mechanisms in SrTiO3-based systems.",1012.2468v1
+2010-12-26,Molecular dynamics simulations of oxide memristors: thermal effects,"We have extended our recent molecular-dynamic simulations of memristors to
+include the effect of thermal inhomogeneities on mobile ionic species appearing
+during operation of the device. Simulations show a competition between an
+attractive short-ranged interaction between oxygen vacancies and an enhanced
+local temperature in creating/destroying the conducting oxygen channels. Such a
+competition would strongly affect the performance of the memristive devices.",1012.5514v1
+2011-01-07,"High-pressure synthesis of rock salt LiMeO2-ZnO (Me = Fe3+, Ti3+) solid solutions","Metastable LiMeO2-ZnO (Me = Fe3+, Ti3+) solid solutions with rock salt
+crystal structure have been synthesized by solid state reaction of ZnO with
+LiMeO2 complex oxides at 7.7 GPa and 1350-1450 K. Structure, phase composition,
+thermal stability and thermal expansion of the recovered samples have been
+studied by X-ray diffraction with synchrotron radiation. At ambient pressure
+rock salt LiMeO2-ZnO solid solutions are kinetically stable up to 670-800 K
+depending on the composition.",1101.1386v1
+2011-01-14,In-Situ Grown Erbium-Doped Dielectric Nanoparticles in Silica-Based Transparent Optical Fibers,"An efficient method to fabricate transparent glass ceramic fibers containing
+in-situ grown Er3+-doped oxide nanoparticles is presented. Characterization of
+the drawn fibers exhibits low loss (0.4 dB/m) and broadened Er3+ emission
+spectrum. This attractive method offers new scopes for fiber amplifiers.",1101.2814v2
+2011-02-03,Medium Energy Ion Scattering of Gr on SiC(0001) and Si(100),"Depth profiling of graphene with high-resolution ion beam analysis is a
+practical method for analysis of monolayer thicknesses of graphene. Not only is
+the energy resolution sufficient to resolve graphene from underlying SiC, but
+by use of isotope labeling it is possible to tag graphene generated from
+reacted ethylene. Furthermore, we are able to analyze graphene supported by
+oxidized Si(100) substrates, allowing the study of graphene films grown by
+chemical vapor deposition on metal and transfered to silicon. This introduces a
+powerful method to explore the fundamentals of graphene formation.",1102.0675v1
+2011-02-25,"Orbital ordering, ferroelasticity, and the large pressure induced volume collapse in PbCrO3","We report a new tetragonal ground-state for perovskite-structured PbCrO3 from
+DFT+U calculations, and explain its anomalously large volume. The new structure
+is stabilized due to orbital ordering of Cr-d in the presence of a large
+tetragonal crystal field, mainly due to off-centering of the Pb atom. At higher
+pressures (smaller volumes) there is a first-order transition to a cubic phase
+where the Cr-d orbitals are orbitally liquid. This phase-transition is
+accompanied by a ~11.5% volume collapse, one of the largest known for
+transition-metal oxides. The large ferroelasticity and its strong coupling to
+the orbital degrees of freedom could be exploited to form potentially useful
+magnetostrictive materials",1102.5323v1
+2011-04-05,Isotope effect in the pseudogap of high-temperature superconducting copper oxides,"We study cuprates within Dynamical Cluster Approximation and find the
+pseudogap displays an isotope effect of the same sign as observed
+experimentally. Notwithstanding the non-phononic origin of the pseudogap the
+interplay between electronic repulsion and retarded phonon-mediated attraction
+gives rise to an isotope dependence of the antinodal spectra. Due to the strong
+momentum differentiation, such interplay is highly non-trivial and leads to the
+simultaneous presence of heavier quasiparticles along the nodal direction. We
+predict an isotope effect in electron-doped materials.",1104.0940v1
+2011-04-05,Observation of asymmetric spectrum broadening induced by silver nanoparticles in a heavy-metal oxide glass,"We demonstrate experimentally and support by a theoretical analysis an effect
+of asymmetric spectrum broadening, which results from doping of silver
+nanoparticles into a heavy-glass matrix, 90(0.5WO3-0.3SbPO4-0.2PbO)-10AgCl. The
+strong dispersion of the effective nonlinear coefficient of the composite
+significantly influences the spectral broadening via the self-phase modulation,
+and leads to a blue upshift of the spectrum. Further extension of the spectrum
+towards shorter wavelengths is suppressed by a growing loss caused by the
+plasmon resonance in the silver particles. The red-edge spectral broadening is
+dominated by the stimulated Raman Scattering.",1104.0952v1
+2011-04-07,Detection of melting by in-situ observation of spherical-drop formation in laser-heated diamond-anvil cells,"A simple method for detection of melting event in laser-heated diamond anvil
+cells (DACs) is introduced. The melting is registered optically by the
+formation of spherical drops of the investigated material as heated in an inert
+pressure transmitting medium. Feasibility of the method is demonstrated on the
+examples of metal (iron and gold) and iron oxide (Fe2O3), materials molten at
+pressures over 40 GPa employing a portable laser heating system.",1104.1304v1
+2011-04-11,Tunable 2-dimensional/3-dimensional electron gases by submonolayer La doping of SrTiO_{3},"First-principles calculation was used to study the structural and electronic
+features of the low dimensional oxide structure,
+SrTiO_{3}/Sr_{1-x}La_{x}TiO_{3} (x=0.25) superlattices, constructed by
+submonolayer low dimensional La doping into SrTiO_{3}. We demonstrate a
+dimensionality crossover from three-dimensional to two-dimensional (3D \to 2D)
+electronic behavior in the system. Two types of carriers, one confined to 2D
+and the other extended, exhibit distinct tunable (3D \to 2D) transport
+characteristics that will enable the study of many properties (e.g.,
+superconductivity) through this change in dimensionality.",1104.1921v1
+2011-04-12,The Role of Intermediate States in Low-Velocity Friction between Amorphous Surfaces,"Simulated sliding between an oxidized silicon tip and surface over six
+decades of velocity using accelerated molecular dynamics reproduces the
+experimentally observed velocity dependence of the friction force. Unlike in
+the crystalline case, as increasing force is applied to the amorphous tip
+intermediate states arise. These intermediate states serve as critical
+transition pathways. The emergence of such states leads to the emergence of a
+plateau in sliding velocity at lower sliding speeds and higher temperatures. A
+simple theory based on these observations successfully describes both the
+experimental and the simulated data.",1104.2226v1
+2011-04-13,Single-molecule interfacial electron transfer dynamics manipulated by external electric current,"Interfacial electron transfer (IET) dynamics in 1,1'-dioctadecyl-3, 3, 3',
+3'-tetramethylindodicarbocyanine (DiD) dye molecules / indium tin oxide (ITO)
+film system have been probed at the ensemble and single-molecule level by
+recording the change of fluorescence emission intensity. By comparing the
+difference of the external electric current (EEC) dependence of lifetime and
+intensity for enambles and single molecules, it is shown that the
+single-molecule probe can effcienly demonstrate the IET dynamics. The backward
+electron transfer and electron transfer of ground state induce the single
+molecules fluorescence quenching when an EEC is applied to ITO film.",1104.2361v1
+2011-04-15,Laterally proximized aluminum tunnel junctions,"This letter presents experiments on junctions fabricated by a new technique
+that enables the use of high quality aluminum oxide tunnel barriers with normal
+metal electrodes at low temperatures. Inverse proximity effect is applied to
+diminish the superconductivity of an aluminum dot through a clean lateral
+connection to a normal metal electrode. To demonstrate the effectiveness of
+this method, fully normal-state single electron transistors (SET) and normal
+metal-insulator-superconductor (NIS) junctions applying proximized Al junctions
+were fabricated. The transport characteristics of the junctions were similar to
+those obtained from standard theoretical models of regular SETs and NIS
+junctions.",1104.3052v1
+2011-05-04,Strain-induced interface reconstruction in epitaxial heterostructures,"We investigate in the framework of Landau theory the distortion of the strain
+fields at the interface of two dissimilar ferroelastic oxides that undergo a
+structural cubic-to-tetragonal phase transition. Simple analytical solutions
+are derived for the dilatational and the order parameter strains that are
+globally valid over the whole of the heterostructure. The solutions reveal that
+the dilatational strain exhibits compression close to the interface which may
+in turn affect the electronic properties in that region.",1105.0860v2
+2011-05-05,Determination of characteristic relaxation times and their significance in glassy disordered insulators,"We revisit the field effect procedure used to characterise the slow dynamics
+of glassy Anderson insulators. It is shown that in the slowest systems the
+procedure fails and the ""characteristic"" time values extracted are not
+intrinsic but determined by the experimental procedure itself. In other cases
+(like lightly doped indium oxide) qualitative indications about the dynamics
+might be obtained, however the times extracted cannot be seen as characteristic
+relaxation times of the system in any simple manner, and more complete
+experiments are necessary. Implications regarding the effect of carrier
+concentration on the emergence of glassiness are briefly outlined.",1105.0984v2
+2011-05-23,Molecular dynamics simulations of oxide memristors: crystal field effects,"We present molecular-dynamic simulations of memory resistors (memristors)
+including the crystal field effects on mobile ionic species such as oxygen
+vacancies appearing during operation of the device. Vacancy distributions show
+different patterns depending on the ratio of a spatial period of the crystal
+field to a characteristic radius of the vacancy-vacancy interaction. There are
+signatures of the orientational order and of spatial voids in the vacancy
+distributions for some crystal field potentials. The crystal field stabilizes
+the patterns after they are formed, resulting in a non-volatile switching of
+the simulated devices.",1105.4445v1
+2011-06-10,Electrostatic effects on contacts to carbon nanotube transistors,"We use numerical simulations to investigate the effect of electrostatics on
+the source and drain contacts of carbon nanotube field-effect transistors. We
+find that unscreened charge on the nanotube at the contact-channel interface
+leads to a potential barrier that can significantly hamper transport through
+the device. This effect is largest for intermediate gate voltages and for
+contacts near the ohmic-Schottky crossover, but can be mitigated with a
+reduction in the gate oxide thickness. These results help to elucidate the
+important role that contact geometry plays in the performance of carbon
+nanotube electronic devices.",1106.2186v1
+2011-06-20,Giant Flexoelectric Effect in Ferroelectric Epitaxial Thin Films,"We report on nanoscale strain gradients in ferroelectric HoMnO3 epitaxial
+thin films, resulting in a giant flexoelectric effect. Using grazing-incidence
+in-plane X-ray diffraction, we measured strain gradients in the films, which
+were 6 or 7 orders of magnitude larger than typical values reported for bulk
+oxides. The combination of transmission electron microscopy, electrical
+measurements, and electrostatic calculations showed that flexoelectricity
+provides a means of tuning the physical properties of ferroelectric epitaxial
+thin films, such as domain configurations and hysteresis curves.",1106.3792v1
+2011-06-22,Voltage percolation thresholds evidenced in the electrical behaviour of different nanostructures,"Percolation phenomena are investigated and discussed in three kinds of
+nanostructures: first two are nanocrystalline silicon-based systems, Si
+nanodots embedded in amorphous SiO2 matrix and porous silicon formed by an
+oxidized nanowire network, and the third consisting of a multi-walled carbon
+nanotube network embedded in amorphous SiN. The current-voltage characteristics
+measured on first two systems present voltage percolation thresholds with the
+same shape - a saturation plateau region of the current, followed by an abrupt
+increase. The current-voltage and conductance-voltage curves measured on
+multi-walled carbon nanotube network embedded in amorphous SiN present
+non-periodic and temperature independent oscillations. These oscillations are
+interpreted as voltage percolation thresholds.",1106.4419v1
+2011-06-27,Graphene microwave transistors on sapphire substrates,"We have developed metal-oxide graphene field-effect transistors (MOGFETs) on
+sapphire substrates working at microwave frequencies. For monolayers, we obtain
+a transit frequency up to ~ 80 GHz for a gate length of 200 nm, and a power
+gain maximum frequency of about ~ 3 GHz for this specific sample. Given the
+strongly reduced charge noise for nanostructures on sapphire, the high
+stability and high performance of this material at low temperature, our MOGFETs
+on sapphire are well suited for a cryogenic broadband low-noise amplifier.",1106.5529v1
+2011-07-08,Dynamically controlled charge sensing of a few-electron silicon quantum dot,"We report charge sensing measurements of a silicon metal-oxide-semiconductor
+quantum dot using a single-electron transistor as a charge sensor with dynamic
+feedback control. Using digitallycontrolled feedback, the sensor exhibits
+sensitive and robust detection of the charge state of the quantum dot, even in
+the presence of charge drifts and random charge rearrangements. The sensor
+enables the occupancy of the quantum dot to be probed down to the single
+electron level.",1107.1557v1
+2011-07-27,High-frequency asymptotic behavior of self-energies in quantum impurity models,"We present explicit expressions for the high-frequency asymptotic behavior of
+electron self-energy of general quantum impurity models, which may be useful
+for improving the convergence of dynamical mean-field calculations and for the
+analytic continuation of the electron self-energy. We also give results,
+expressed in more physical terms, for the two-orbital and three-orbital
+rotationally invariant Slater-Kanamori interactions, in order to facilitate
+calculations of transition metal oxides.",1107.5536v1
+2011-07-28,Phase transition close to room temperature in BiFeO3 thin films,"BiFeO3 (BFO) multiferroic oxide has a complex phase diagram that can be
+mapped by appropriately substrate-induced strain in epitaxial films. By using
+Raman spectroscopy, we conclusively show that films of the so-called
+supertetragonal T-BFO phase, stabilized under compressive strain, displays a
+reversible temperature-induced phase transition at about 100\circ, thus close
+to room temperature.",1107.5801v1
+2011-08-03,Switching magnetoresistance in vertically interfaced Pr0.5Ca0.5MnO3 grown on ZnO nanowires,"The synthesis, morphology and magneto-transport properties of
+nanostructure-engineered charge-ordered Pr0.5Ca0.5MnO3 grown on ZnO nanowires
+are reported. The stability of the charge-ordering can be tuned, but more
+interestingly the sign of the magnetoresistance is inverted at low
+temperatures. Coexistence of ferromagnetic clusters on the surface and
+antiferromagnetic phase in the core of the grains were considered in order to
+understand these features. This work suggests that such a process of growing on
+nanowires network can be readily extended to other transition metal oxides and
+open doors towards tailoring their functionalities.",1108.0765v1
+2011-08-09,Interface-induced d-wave pairing,"We discuss a scenario for interface-induced superconductivity involving
+pairing by dipolar excitations proximate to a two-dimensional electron system
+controlled by a transverse electric field. If the interface consists of
+transition metal oxide materials, the repulsive on-site Coulomb interaction is
+typically strong and a superconducting state is formed via exchange of
+non-local dipolar excitations in the d-wave channel. Perspectives to enhance
+the superconducting transition temperature are discussed.",1108.1942v1
+2011-08-12,Ferromagnetism in semiconductors and oxides: prospects from a ten years' perspective,"Over the last decade the search for compounds combining the resources of
+semiconductors and ferromagnets has evolved into an important field of
+materials science. This endeavour has been fuelled by continual demonstrations
+of remarkable low-temperature functionalities found for ferromagnetic
+structures of (Ga,Mn)As, p-(Cd,Mn)Te, and related compounds as well as by ample
+observations of ferromagnetic signatures at high temperatures in a number of
+non-metallic systems. In this paper, recent experimental and theoretical
+developments are reviewed emphasising that, from the one hand, they disentangle
+many controversies and puzzles accumulated over the last decade and, on the
+other, offer new research prospects.",1108.2582v1
+2011-09-13,Fabrication and Room-Temperature Single-Charging Behavior of Self-Aligned Single-Dot Memory Devices,"Self-aligned single-dot memory devices and arrays were fabricated based on
+arsenic-assisted etching and oxidation effects. The resulting device has a
+floating gate of about 5-10 nm, presenting single-electron memory operation at
+room temperature. In order to realize the final single-electron memory circuit,
+this paper investigates process repeatability, device uniformity in single-dot
+memory arrays, device scalability, and process transferability to an industrial
+application.",1109.2921v1
+2011-09-13,Optimisation and Simulation of an Alternative nano-flash Memory: the SASEM device,"Process simulation are performed in order to simulate the full fabrication
+process of an alternative nano-flash memory in order to optimise it and to
+improve the understanding of the dot storage formation. The influence of
+various parameters (oxidation temperature, nanowire shape) have been
+investigated.",1109.2927v2
+2011-09-20,Electric breakdown effect in the current-voltage characteristics of amorphous indium oxide thin films near the superconductor-insulator transition,"Current-voltage characteristics in the insulator bordering superconductivity
+in disordered thin films exhibit current jumps of several orders of magnitude
+due to the development of a thermally bistable electronic state at very low
+temperatures. In this high-resolution study we find that the jumps can be
+composed of many (up to 100) smaller jumps that appear to be random. This
+indicates that inhomogeneity develops near the transition to the insulator and
+that the current breakdown proceed via percolative paths spanning from one
+electrode to the other.",1109.4406v1
+2011-09-22,Intrinsic coupling of orbital excitations to spin fluctuations in Mott insulators,"We show how the general and basic asymmetry between two fundamental degrees
+of freedom present in strongly correlated oxides, spin and orbital, has very
+profound repercussions on the elementary spin and orbital excitations. Whereas
+the magnons remain largely unaffected, orbitons become inherently coupled with
+spin fluctuations in spin-orbital models with antiferromagnetic and
+ferroorbital ordered ground states. The composite orbiton-magnon modes that
+emerge fractionalize again in one dimension, giving rise to spin-orbital
+separation in the peculiar regime where spinons are faster than orbitons.",1109.4745v1
+2011-09-26,"Hidden symmetries in a gauge covariant approach, Hamiltonian reduction and oxidation","Hidden symmetries in a covariant Hamiltonian formulation are investigated
+involving gauge covariant equations of motion. The special role of the
+Stackel-Killing tensors is pointed out. A reduction procedure is used to reduce
+the original phase space to another one in which the symmetries are divided
+out. The reverse of the reduction procedure is done by stages performing the
+unfolding of the gauge transformation followed by the Eisenhart lift in
+connection with scalar potentials.",1109.5449v1
+2011-10-07,Power comparison of CMOS and adiabatic full adder circuit,"Full adders are important components in applications such as digital signal
+processors (DSP) architectures and microprocessors. Apart from the basic
+addition adders also used in performing useful operations such as subtraction,
+multiplication, division, address calculation, etc. In most of these systems
+the adder lies in the critical path that determines the overall performance of
+the system. In this paper conventional complementary metal oxide semiconductor
+(CMOS) and adiabatic adder circuits are analyzed in terms of power and
+transistor count using 0.18UM technology.",1110.1549v1
+2011-10-10,Evidences of Superconductivity without Direct Relation to Valence Electron Density in Metal Doped Y123 Cuprates,"We investigated systemically YBa2Cu3-x(Fe, Co, Al, Zn)xO7-{\delta}
+(x=0.0\sim0.5) cuprates through the XRD, the test of superconductivity, oxygen
+contents,positron annihilation technology and simulated calculations. The
+experimental results and theoretic calculations support such a conclusion that
+the Tc does not depend directly on the density of valence electron in the
+samples. Moreover, whether or not it may imply some correlations between
+Fe-oxide superconductors and cuprates that Fe doped Y123 samples show some
+unique characteristics.",1110.2499v1
+2011-10-14,Quantification of correlations in quantum many-particle systems,"We introduce a well-defined and unbiased measure of the strength of
+correlations in quantum many-particle systems which is based on the relative
+von Neumann entropy computed from the density operator of correlated and
+uncorrelated states. The usefulness of this general concept is demonstrated by
+quantifying correlations of interacting electrons in the Hubbard model and in a
+series of transition-metal oxides using dynamical mean-field theory.",1110.3214v3
+2011-12-07,Modified Mott-Schottky Analysis of Nanocrystal Solar Cells,"Mott-Schottky analysis is adapted to determine the built-in bias (Vbi) and
+doping density (N) of lead sulfide-zinc oxide colloidal quantum dot
+heterojunction solar cells. We show that charge injection barriers at the solar
+cell's electrodes create a constant capacitance that distorts the junction's
+depletion capacitance and result in erroneous Vbi and N values when determined
+through Mott-Schottky analysis. The injection barrier capacitance is taken into
+account by incorporating a constant capacitance in parallel with the depletion
+capacitance.",1112.1623v1
+2011-12-12,Relaxor ferroelectric behavior and structural aspects of SrNaBi2Nb3O12 ceramics,"SrNaBi2Nb3O12 powder was prepared via the conventional solid-state reaction
+method. X-ray structural studies confirmed the phase to be a three-layered
+member of the Aurivillius family of oxides. SrNaBi2Nb3O12 (SNBN) ceramics
+exhibited the typical characteristics of relaxor ferroelectrics, associated
+with broad and dispersive dielectric maxima. The variation of temperature of
+dielectric maxima (Tm) with frequency obeyed the Vogel-Fulcher relationship.
+Relaxor behavior was believed to be arising from the cationic disorder at
+A-site. Pinched ferroelectric hysteresis loops were observed well above Tm.",1112.2416v1
+2011-12-21,Exploring spin-orbital models with dipolar fermions in zig-zag optical lattices,"Ultra-cold dipolar spinor fermions in zig-zag type optical lattices can mimic
+spin-orbital models relevant in solid-state systems, as transition-metal oxides
+with partially filled d-levels, with the interesting advantage of reviving the
+quantum nature of orbital fluctuations. We discuss two different physical
+systems in which these models may be simulated, showing that the interplay
+between lattice geometry and spin-orbital quantum dynamics produces a wealth of
+novel quantum phases.",1112.5082v2
+2011-12-22,Electric field effect on superconductivity at complex oxide interfaces,"We examine the enhancement of the interfacial superconductivity between
+LaAlO$_{3}$ and SrTiO$_{3}$ by an effective electric field. Through the
+breaking of inversion symmetry at the interface, we show that a term coupling
+the superfluid density and an electric field can augment the superconductivity
+transition temperature. Microscopically, we show that an electric field can
+also produce changes in the carrier density by relating the measured
+capacitance to the density of states. Through the electron-phonon induced
+interaction in bulk SrTiO$_{3}$, we estimate the transition temperature.",1112.5466v2
+2012-02-07,Interplay between strain and oxygen vacancies in lanthanum aluminate,"We evaluate the interplay between epitaxial strain and oxygen vacancy
+formation in the perovskite-structure oxide lanthanum aluminate, LaAlO$_3$.
+Using density functional theory within the GGA$+U$ approximation we calculate
+the dependence of the oxygen vacancy formation energy on the biaxial strain
+conditions. We find that the change in formation energy with strain is
+negligible over the range of strain values usually accessible through coherent
+epitaxial growth. Our findings suggest that experimental reports of different
+oxygen vacancy concentrations in strained films result from extrinsic factors,
+or from other impurities such as defect complexes.",1202.1431v1
+2012-02-20,Elastic properties of freely suspended MoS2 nanosheets,"We study the elastic deformation of few layers (5 to 25) thick freely
+suspended MoS2 nanosheets by means of a nanoscopic version of a bending test
+experiment, carried out with the tip of an atomic force microscope. The Young's
+modulus of these nanosheets is extremely high (E = 0.33 TPa), comparable to
+that of graphene oxide, and the deflections are reversible up to tens of
+nanometers.",1202.4439v1
+2012-02-21,Oxygen vacancy segregation and space-charge effects in grain boundaries of dry and hydrated BaZrO3,"A space-charge model is applied to describe the equilibrium effects of
+segregation of double-donor oxygen vacancies to grain boundaries in dry and wet
+acceptor-doped samples of the perovskite oxide BaZrO3. The grain boundary core
+vacancy concentrations and electrostatic potential barriers resulting from
+different vacancy segregation energies are evaluated. Density-functional
+calculations on vacancy segregation to the mirror-symmetric \Sigma 3 (112)
+[-110] tilt grain boundary are also presented. Our results indicate that oxygen
+vacancy segregation can be responsible for the low grain boundary proton
+conductivity in BaZrO3 reported in the literature.",1202.4570v1
+2012-02-26,A unique metal-semiconductor interface and resultant electron transfer phenomenon,"An unusual electron transfer phenomenon has been identified from an n-type
+semiconductor to Schottky metal particles, the result of a unique metal
+semiconductor interface that results when the metal particles are grown from
+the semiconductor substrate. The unique interface acts as a one-way
+(rectifying) open gateway and was first identified in reduced rutile
+polycrystalline titanium dioxide (an n-type semiconductor) to Group VIII
+(noble) metal particles. The interface significantly affects the Schottky
+barrier height resulting in electron transfer to the metal particles from the
+reduced rutile titanium dioxide (TiO2) based on their respective work
+functions. The result is a negative charge on the metal particles which is of
+sufficient magnitude and duration to provide cathodic protection of the metal
+particles from surface oxidation.",1202.5771v1
+2012-03-24,4f and 5d levels of Ce3+ in D2 eightfold oxygen coordination,"The effects on the 4f and 5d levels of Ce3+ of its first coordination shell
+geometry in Ce-doped oxides with a D2 8-fold site, like garnets, are studied
+with embedded cluster, wave function based ab initio methods. The only
+deformations of a CeO8 cube that are found to shift the lowest 4f-5d transition
+to the red are the symmetric Ce-O bond compression and the tetragonal symmetric
+bond bending. These results are analyzed in terms of centroid and ligand field
+stabilization energy differences. The splittings of the upper 5d levels and of
+the 4f levels are also discussed.",1203.5391v1
+2012-06-21,Symmetrical field effect and slow electron relaxation in granular aluminium,"Conductivity and field effect measurements in thin insulating Al granular
+films are reported. The occurrence of a symmetrical field effect and of very
+slow conductance relaxations is demonstrated. They are identical to the
+electron glassy behaviours already reported in insulating indium oxide thin
+films. The results suggest that the phenomena are quite general. The study of
+structurally discontinuous samples should help to understand the origin and
+mechanism of the glassy behaviour.",1206.4978v1
+2012-07-16,Optimal T$_c$ of cuprates: role of screening and reservoir layers,"We explore the role of charge reservoir layers (CRLs) on the superconducting
+transition temperature of cuprate superconductors. Specifically, we study the
+effect of CRLs with efficient short distance dielectric screening coupled
+capacitively to copper oxide metallic layers. We argue that dielectric
+screening at short distances and at frequencies of the order of the
+superconducting gap, but small compared to the Fermi energy can significantly
+enhance T$_c$, the transition temperature of an unconventional superconductor.
+We discuss the relevance of our qualitative arguments to a broader class of
+unconventional superconductors.",1207.3584v1
+2012-06-29,On the algorithmic behaviour of complex physical systems,"Starting from the idea that the underlying mechanisms driving the observable
+processes in nature are algorithmic, we exemplify this in two ways: nature
+works as a computing machine and thus the processes running on it optimize
+themselves in an intrinsic manner so as to save time. As a first example we
+will place the empirical analysis of oxidation in the context of algorithm
+complexity analysis. Second, we will show that deformations suffered by a
+shape-memory alloy may be produced by nature showing a LIFO (Last In First Out)
+behaviour.",1207.5398v1
+2012-08-03,"Accurate screened exchange band structures for transition metal monoxides MnO, FeO, CoO and NiO","We report calculations of the band structures and density of states of the
+four transition metal monoxides MnO, FeO, CoO and NiO using the hybrid density
+functional sX-LDA. Late transition metal oxides are prototypical examples of
+strongly correlated materials, which pose challenges for electronic structure
+methods. We compare our results with available experimental data and show that
+our calculations yield accurate predictions for the fundamental band gaps and
+valence bands of FeO, CoO and NiO. For MnO, the band gaps are underestimated,
+suggesting additional many-body effects that are not captured by our screened
+hybrid functional approach.",1208.0786v2
+2012-08-07,Superlattice Based on Graphene on a Strip Substrate,"A graphene-based superlattice formed due to the periodic modulation of the
+band gap has been investigated. Such a modulation is possible in graphene
+deposited on a strip substrate made of silicon oxide and hexagonal boron
+nitride. The advantages and some possible problems in the superlattice under
+consideration are discussed. A model describing such a superlattice is proposed
+and the dispersion relation between the energy and momentum of carriers has
+been obtained using the transfer matrix method within this model.",1208.1442v1
+2012-08-09,Disorder-free sputtering method on graphene,"Deposition of various materials onto graphene without causing any disorder is
+highly desirable for graphene applications. Especially, sputtering is a
+versatile technique to deposit various metals and insulators for spintronics,
+and indium tin oxide to make transparent devices. However, the sputtering
+process causes damage to graphene because of high energy sputtered atoms. By
+flipping the substrate and using a high Ar pressure, we demonstrate that the
+level of damage to graphene can be reduced or eliminated in dc, rf, and
+reactive sputtering processes.",1208.1835v1
+2012-08-24,Car-Parrinello Simulation of the Reaction of Aluminium with Oxygen,"We present Car-Parrinello molecular dynamics simulations of the initial
+reaction steps leading to an inert oxide layer on aluminium. The mechanism of
+the reaction of the aluminium surface with single oxygen molecules is analysed.
+After adsorption at the surface the oxygen molecules dissociate at a
+femtosecond timescale and the atoms are chemisorbed at the surface at a
+distance of several angstrom. When the aluminium surface is exposed to higher
+oxygen pressure, a surface layer essentially consisting of threefold
+coordinated oxygen atoms starts to form.",1208.4969v2
+2012-10-10,Orientation dependent work function of in situ annealed strontium titanate,"We have used energy filtered x-ray photoelectron emission microscopy (XPEEM)
+and synchrotron radiation to measure the grain orientation dependence of the
+work function of a sintered niobium doped strontium titanate ceramic. A
+significant spread in work function values is found. Grain orientation and
+surface reducing/oxidizing conditions are the main factors in determining the
+work function. Energy filtered XPEEM looks ideally suited for analysis of other
+technologically interesting polycrystalline samples.",1210.3086v1
+2012-10-22,New insights into the phase diagram of the copper oxide superconductors from electronic Raman scattering,"Mechanism of unconventional superconductivity is still unknown even if more
+than 25 years have been passed since the discovery of high-Tc cuprate
+superconductors by J.G. Bednorz and K. A. Muller. Here, we explore the cuprate
+phase diagram by electronic Raman spectroscopy and shed light on the
+superconducting state in hole doped cuprates. Namely, how superconductivity and
+the critical temperature Tc are impacted by the pseudogap.",1210.5972v1
+2013-02-15,An innovative approach of structural instabilities in tetragonal tungsten bronze crystals through the concept of rigid unit modes,"Tetragonal tungsten bronze (TTB) oxides are one of the most important classes
+of ferroelectrics. Many of these framework structures undergo ferroelastic
+transformations related to octahedron tilting deformations. Such tilting
+deformations are closely related to the Rigid Unit Modes (RUMs). This paper
+discusses the whole set of RUMs in an ideal TTB lattice and possible crystal
+structures which can emerge owing to the condensation of some of them. Analysis
+of available experimental data for the TTB-like niobates lends credence to the
+obtained theoretical predictions.",1302.3692v2
+2013-03-09,Low-temperature thermal expansion of rock-salt ZnO,"Lattice parameter of metastable high-pressure phase of zinc oxide, rock-salt
+ZnO was measured in the 10-300 K temperature range using synchrotron X-ray
+powder diffraction. No phase transition was observed down to 10 K. The lattice
+parameter of rock-salt ZnO was found to increase from 4.266 {\AA} in the 10-80
+K range up to 4.2752(3) {\AA} at 298 K, while the volume thermal expansion
+coefficient increases from slight negative values below 40 K up to
+4.77\times10^-5 K^-1 at 298 K.",1303.2216v1
+2013-03-12,The chemistry of dust formation in red supergiants,"Massive stars in their late stages of evolution as Red Supergiants experience
+mass loss. The resulting winds show various degrees of dynamical and chemical
+complexity and produce molecules and dust grains. This review summarises our
+knowledge of the molecular and dust components of the wind of Red Supergiants,
+including VY CMa and Betelgeuse. We discuss the synthesis of dust as a
+non-equilibrium process in stellar winds, and present the current knowledge of
+the chemistry involved in the formation of oxygen-rich dust such as silicates
+and metal oxides.",1303.2805v1
+2013-03-15,Insulator-to-metal transition of SrTiO3:Nb single crystal surfaces induced by Ar+ bombardment,"In this paper, the effect of Ar+ bombardment of SrTiO3:Nb surface layers is
+investigated on the macro- and nanoscale using surface-sensitive methods. After
+bombardment, the stoichiometry and electronic structure are changed distinctly
+leading to an insulator-to-metal transition related to the change of the Ti ""d""
+electron from d0 to d1 and d2. During bombardment, conducting islands are
+formed on the surface. The induced metallic state is not stable and can be
+reversed due to a redox process by external oxidation and even by
+self-reoxidation upon heating the sample to temperatures of 300{\deg}C.",1303.3760v1
+2013-03-26,High performance fiber-coupled NbTiN superconducting nanowire single photon detectors with Gifford-McMahon cryocooler,"We present high performance fiber-coupled niobium titanium nitride
+superconducting nanowire single photon detectors fabricated on thermally
+oxidized silicon substrates. The best device showed a system detection
+efficiency (DE) of 74%, dark count rate of 100 c/s, and full width at half
+maximum timing jitter of 68 ps under a bias current of 18.0 uA with a practical
+Gifford-McMahon cryocooler system. We also introduced six detectors into the
+cryocooler and confirmed that the system DE of all detectors was higher than
+67% at the dark count rate of 100 c/s.",1303.6381v2
+2013-04-05,Fermi level density of states modulation without charge transfer in nickelate superlattices,"By using first-principles density functional theory calculations for
+(LaNiO3)m/(SrTiO3)n superlattices, we report a systematic way of electronic
+response to the interface geometry. It is found that Fermi level density of
+states of metallic nickelate layers is significantly reduced without charge
+transfer in the vicinity of interface to the insulating SrTiO3. This type of
+electronic state redistribution is clearly distinctive from other interface
+phenomena such as charge and orbital reconstruction. Our result sheds new light
+towards understanding the nickelates and other transitionmetal oxide
+heterostructures.",1304.1615v2
+2013-04-23,Superconducting and Pseudogap effects on the interplane conductivity and Raman scattering cross section in the two dimensional Hubbard Model,"Cluster dynamical mean field methods are used to calculate the
+superconductivity-induced changes in the interplane conductivity and Raman
+scattering cross section of the two dimensional Hubbard model. When
+superconductivity emerges from the pseudogap, the superconducting response is
+found to be diminished in amplitude, broadened and, in the case of the
+interplane conductivity, shifted to higher frequency. The results are in
+agreement with data on high temperature copper-oxide superconductors indicating
+that the Hubbard model contains the essential low energy physics of the
+pseudogap and its interplay with superconductivity in the cuprates.",1304.6406v1
+2013-04-30,Mechanism of Polarization Fatigue in BiFeO3: the Role of Schottky Barrier,"By using piezoelectric force microscopy and scanning Kelvin probe microscopy,
+we have investigated the domain evolution and space charge distribution in
+planar BiFeO3 capacitors with different electrodes. It is observed that charge
+injection at the film/electrode interface leads to domain pinning and
+polarization fatigue in BiFeO3. Furthermore, the Schottky barrier at the
+interface is crucial for the charge injection process. Lowering the Schottky
+barrier by using low work function metals as the electrodes can also improve
+the fatigue property of the device, similar to what oxide electrodes can
+achieve.",1304.7935v1
+2013-05-20,Antiferromagnetic Ising model saturation field entropies: ladders and kagome lattice,"Saturation field entropies of antiferromagnetic Ising models on quasi
+one-dimensional lattices (ladders) and the kagome lattice are calculated. The
+former is evaluated exactly by constructing the corresponding transfer
+matrices, while the latter calculation uses Binder's algorithm for efficiently
+and exactly computing the partition function of over 1300 spins to give, in
+Boltzmann's units, S = 0.393589(6). We comment on the relation of the kagome
+lattice to the experimental situation in the spin-ice compound dysprosium
+titanium oxide.",1305.4606v2
+2013-05-24,Efficient Single Photon Absorption by Optimized Superconducting Nanowire Geometries,"We report on simulation results that shows optimum photon absorption by
+superconducting nanowires can happen at a fill-factor that is much less than
+100%. We also present experimental results on high performance of our
+superconducting nanowire single photon detectors realized using NbTiN on
+oxidized silicon.",1305.5832v1
+2013-06-12,Optical absorption and emission of silicon nanocrystals: From single to collective response,"We report on the possibility of describing the absorption and emission
+characteristics of an ensemble of silicon nanocrystals (NCs) with realistic
+distributions in the NC size, by the sum of the reponses of the single NCs. The
+individual NC responses are evaluated by means of ab-initio theoretical
+calculations and the summation is performed by taking into account the trend of
+the optical properties as a function of NC size and oxidation degree. The
+comparison with experimental results shows a nice matching of the spectra, also
+without any tuning of the parameters. Finally, the possibility of adapting the
+model in order to reproduce the experimental data is explored and discussed.",1306.2785v1
+2013-06-26,Layer-resolved study of Mg atom incorporation at MgO/Ag(001) buried interface,"By combining x-ray excited Auger electron diffraction experiments and
+multiple scattering calculations we reveal a layer-resolved shift for the Mg
+KL23L23 Auger transition in MgO ultrathin films (4-6 \AA) on Ag(001). This
+resolution is exploited to demonstrate the possibility to control Mg atoms
+incorporation at the MgO/Ag(001) interface by exposing the MgO films to a Mg
+flux. A substantial reduction of the MgO/Ag(001) work function is observed
+during the exposition phase and reflects, both band-offset variations at the
+interface and band bending effects in the oxide film.",1306.6158v1
+2013-07-23,Thermodynamic stability of new phase Bi12.5Sm1.5ReO24.5,"The Bi12.5Sm1.5ReO24.5 phase has been synthesized for the first time. The
+preparation of Bi12.5Sm1.5ReO24.5 has been performed by solid-state reaction
+from Bi2O3, Gd2O3, Re2O7. The X-ray measurements have showed that
+Bi12.5Sm1.5ReO24.5 was cubic structure (space group Fm3m). The standard molar
+enthalpy of formation of Bi12.5Sm1.5ReO24.5 has been determined by solution
+calorimetry combining the enthalpies of dissolution of Bi12.5Sm1.5ReO24.5 and
+6.25Bi2O3 + 0.75Sm2O3 + 0.5Re2O7 mixture in 2 M HCl and literature data. It has
+been obtained that above-mentioned phase is thermodynamically stable with
+respect to their decomposition into binary oxides at room temperatures.",1307.5938v1
+2013-07-24,"Charge expulsion, charge inhomogeneity and phase separation in dynamic Hubbard models","Dynamic Hubbard models are extensions of the conventional Hubbard model that
+take into account the fact that atomic orbitals expand upon double occupancy.
+It is shown here that systems described by dynamic Hubbard models have a
+tendency to expel negative charge from their interior to the surface, and to
+develop charge inhomogeneity and even phase separation in the bulk. These
+effects are associated with lowering of electronic kinetic energy. We propose
+that these models may explain the charge inhomogeneity and negatively charged
+grain boundaries observed in cuprate oxides and other materials.",1307.6526v1
+2013-10-10,Dynamics of Coalescence-Induced Jumping Water Droplets,"This fluid dynamics video shows the different interaction mechanisms of
+coalescence-induced droplet jumping during condensation on a nanostructured
+superhydrophobic surface. High speed imaging was used to show jumping behavior
+on superhydrophobic copper oxide and carbon nanotube surfaces. Videos
+demonstrating multi-jumping droplets, jumping droplet return to the surface,
+and droplet-droplet electrostatic repulsions were analyzed. Experiments using
+external electric fields in conjunction with high speed imaging in a custom
+built experimental chamber were used to show that all coalescence-induced
+jumping droplets on superhydrophobic surfaces become positively charged upon
+leaving the surface, which is detailed in the video.",1310.2975v1
+2013-10-24,Temperature dependence of crystal field excitations in CuO,"We report a study on the temperature dependence of the charge-neutral crystal
+field (dd) excitations in cupric oxide, using nonresonant inelastic x-ray
+scattering (IXS) spectroscopy. Thanks to a very high energy resolution (60
+meV), we observe thermal effects on the dd excitation spectrum fine structure
+between temperatures of 10-320 K. With an increasing temperature, the spectra
+broaden considerably. We assign the temperature dependence of the dd
+excitations to the relatively large electron-phonon coupling.",1310.6730v1
+2013-10-29,Thin Film Substrates from the Raman spectroscopy point of view,"We have investigated ten standard single crystal substrates of complex oxides
+on the account of their applicability in the Raman spectroscopy based thin film
+research. In this study we suggest a spectra normalization procedure that
+utilizes a comparison of the substrate Raman spectra to those of
+well-established Raman reference materials. We demonstrate that MgO, LaGaO3,
+(LaAlO3)_0.3(Sr2AlTaO6)_0.7 (LSAT), DyScO3, YAlO3, and LaAlO3 can be of
+potential use for a Raman based thin film research. At the same time TiO2
+(rutile), NdGaO3, SrLaAlO4, and SrTiO3 single crystals exhibit multiple phonon
+modes accompanied by strong Raman background that substantially hinder the
+Raman based thin film experiments.",1310.7966v1
+2013-11-06,The role of screened exact exchange in accurately describing properties of transition metal oxides: Modeling defects in LaAlO3,"The properties of many intrinsic defects in the wide band gap semiconductor
+LaAlO3 are studied using the screened hybrid functional of Heyd, Scuseria, and
+Ernzerhof (HSE). As in pristine structures, exact exchange included in the
+screened hybrid functional alleviates the band gap underestimation problem,
+which is common to semilocal functionals; this allows accurate prediction of
+defect properties. We propose correction-free defect energy levels for bulk
+LaAlO3 computed using HSE that might serve as guide in the interpretation of
+photoluminescence experiments.",1311.1340v1
+2013-11-09,A first principles investigated optical spectra of oxizided graphene,"The electronic and optical properties of mono, di, tri, and tetravacancies in
+graphene are studied in comparison to each other, using density functional
+theory. In addition, oxidized monovacancies are considered for different oxygen
+concentrations. Pristine graphene is found to be more absorptive than any
+defect configuration at low energy. We demonstrate characteristic differences
+in the optical spectra of the various defects for energies up to 3 eV. This
+makes it possible to quantify by optical spectroscopy the ratios of the defect
+species present in a sample.",1311.2213v1
+2013-12-10,Large thermal biasing of individual gated nanostructures,"We demonstrate a novel nanoheating scheme that yields very large and uniform
+temperature gradients up to about 1K every 100nm, in an architecture which is
+compatible with the field-effect control of the nanostructure under test. The
+temperature gradients demonstrated largely exceed those typically obtainable
+with standard resistive heaters fabricated on top of the oxide layer. The
+nanoheating platform is demonstrated in the specific case of a short-nanowire
+device.",1312.2845v3
+2013-12-24,Possibility of obtaining atomic metallic hydrogen by electrochemical method,"In this work we show, that atomic metallic hydrogen (AMH) is formed inside of
+sintered oxide-nickel electrodes of nickel-cadmium battery over a long period
+of electrochemical hydrogenation (more than five years). It was established
+that density AMH is 12 times higher, than the density of liquid molecular
+hydrogen, the specific energy of hydrogen recombination is 20 times higher than
+of liquid hydrogen-oxygen fuel. At the room temperature AMH is a good
+conductor, but not a superconductor.",1312.6851v1
+2014-01-29,Electrostatic theory of metal whiskers,"Needle shaped whiskers grow on various metal surfaces often across leads of a
+package causing current leakage or short circuits and raising reliability
+issues in electronic components. The nature of metal whiskers remains a mystery
+after several decades of research. Here, the existence of metal whiskers is
+attributed to the energy gain due to electrostatic polarization of needle
+shaped metal filaments in the electric field. The field is induced by surface
+imperfections: contaminations, oxide states, grain boundaries, etc. A proposed
+theory provides closed form expressions and quantitative estimates for the
+whisker nucleation and growth rates, explains the range of whisker parameters
+and effects of external biasing, and predicts statistical distribution of their
+lengths.",1401.7689v1
+2014-02-07,Lithography-free sub-100nm nanocone array antireflection layer for low-cost silicon solar cell,"High density and uniformity sub-100nm surface oxidized silicon nanocone
+forest structure is created and integrated onto the existing texturization
+microstructures on photovoltaic device surface by a one-step high throughput
+plasma enhanced texturization method. We suppressed the broadband optical
+reflection on chemically textured grade-B silicon solar cells for up to 70.25%
+through this nanomanufacturing method. The performance of the solar cell is
+improved with the short circuit current increased by 7.1%, fill factor
+increased by 7.0%, conversion efficiency increased by 14.66%. Our method
+demonstrates the potential to improve the photovoltaic device performance with
+low cost high and throughput nanomanufacturing technology.",1402.1737v1
+2014-02-14,Carrier type modulation in current annealed graphene layers,"We report on the electrical properties of current annealed graphene and few
+layer graphene devices. It is observed that current annealing for several hours
+results the n-type doping in the graphene layers. After current annealing Dirac
+point start to shift toward positive gate voltage and saturate at some fixed
+gate voltage. N-type conduction in current annealed graphene layers is caused
+by the charge trapping in oxide layer during current annealing and recovery of
+charge neutrality point with time span is understood due to the de-trapping of
+charge with time.",1402.3436v1
+2014-04-04,3D Vertical Dual-Layer Oxide Memristive Devices for Neuromorphic Computing,"Dual-layer resistive switching devices with horizontal W electrodes, vertical
+Pd electrodes and WOx switching layer formed at the sidewall of the horizontal
+electrodes have been fabricated and characterized. The devices exhibit
+well-characterized analog switching characteristics and small mismatch in
+electrical characteristics for devices formed at the two layers. The
+three-dimensional (3D) vertical device structure allows higher storage density
+and larger connectivity for neuromorphic computing applications. We show the
+vertical devices exhibit potentiation and depression characteristics similar to
+planar devices, and can be programmed independently with no crosstalk between
+the layers.",1404.1158v1
+2014-04-07,Synthesis of Tungsten Oxide Nanoparticles using a Hydrothermal Method at Ambient Pressure,"Tungstite (WO3.H2O) nanoparticles were synthesized using a simple and
+inexpensive low temperature and low pressure hydrothermal method by adding
+hydrochloric acid to diluted sodium tungstate solutions (Na2WO4.2H2O) at
+temperatures below 5oC. A heat treatment at temperatures at or above 300oC
+resulted in a phase transformation to monoclinic WO3, while preserving the
+nanoparticles morphology. The products were characterized using powder x-ray
+diffraction, transmission electron microscopy (including electron energy-loss
+spectroscopy and electron diffraction) and x-ray photoelectron spectroscopy.",1404.2612v1
+2014-04-14,Theoretical study of charge exchange dynamics in He$^+$ + NO collisions,"We investigate the charge transfer mechanism in the collisions of helium ions
+on nitric oxide using a molecular description framework with consideration of
+the orientation of the projectile toward the target. The anisotropy of the
+collision process has been analysed in detail in connection with the
+non-adiabatic interactions around avoided crossings. Potential energy curves,
+radial and rotational coupling matrix elements have been determined by means of
+ab initio quantum chemical methods. The collision dynamics is performed in the
+[1.-25.] keV collision energy range using a semiclassical approach, and the
+total electron transfer cross sections are analysed with regard to available
+experimental data.",1404.3635v1
+2014-07-31,First-principles study of the multi-mode anti-ferroelectric transition of PbZrO3,"We have studied ab initio the phase transition in PbZrO3, a perovskite oxide
+usually presented as the prototypic anti-ferroelectric material. Our work
+reveals the crucial role that anti-ferrodistortive modes -- involving concerted
+rotations of the oxygen octahedra in the structure -- play in the
+transformation, as they select the observed anti-ferroelectric phase, among
+competing structural variants, via a cooperative trilinear coupling.",1407.8405v1
+2014-08-11,Single- and multi-domain ferroelectricity driven by interfaces,"The design of the interfacial bondings at metal-oxide interfaces yields
+exciting new phenomena and can be a route to sustain, and even promote,
+ferroelectricity at the nanoscale. We study the impact of these interfaces on
+the nature of the spontaneous polarization (single- vs. multi-domain) of
+ferroelectric capacitors. We show that interfacial properties intertwine with
+both ferrolectric and electrode parameters to determine the actual ground state
+of the system. We find analytically the criterion that specifies if
+ferroelectricity appears in a single- or multi- domain fashion as a result of
+this intertwining. The physics behind this criterion suggests new means for
+tailoring ferroelectric functionalities.",1408.2373v1
+2014-08-21,Simulation of Schottky-Barrier Phosphorene Transistors,"Schottky barrier field-effect transistors (SBFETs) based on few and mono
+layer phosphorene are simulated by the non-equilibrium Green's function
+formalism. It is shown that scaling down the gate oxide thickness results in
+pronounced ambipolar I-V characteristics and significant increase of the
+minimal leakage current. The problem of leakage is especially severe when the
+gate insulator is thin and the number of layer is large, but can be effectively
+suppressed by reducing phosphorene to mono or bilayer. Different from
+two-dimensional graphene and layered dichalcogenide materials, both the
+ON-current of the phosphorene SBFETs and the metal-semiconductor contact
+resistance between metal and phosphorene strongly depend on the transport
+crystalline direction.",1408.5013v1
+2014-10-15,Colloidal Plasmonic Titanium Nitride Nanoparticles: Properties and Applications,"Optical properties of colloidal plasmonic titanium nitride nanoparticles are
+examined with an eye on their photothermal via transmission electron microscopy
+and optical transmittance measurements. Single crystal titanium nitride cubic
+nanoparticles with an average size of 50 nm exhibit plasmon resonance in the
+biological transparency window. With dimensions optimized for efficient
+cellular uptake, the nanoparticles demonstrate a high photothermal conversion
+efficiency. A self-passivating native oxide at the surface of the nanoparticles
+provides an additional degree of freedom for surface functionalization.",1410.3920v1
+2014-12-10,Lattice strain at c-Si surfaces: a density functional theory calculation,"The measurement of the Avogadro constant by counting Si atoms is based on the
+assumption that Si balls of about 94 mm diameter have a perfect crystal
+structure up to the outermost atom layers. This not the case because of the
+surface relaxation and reconstruction, the possible presence of an amorphous
+layer, and the oxidation process due to the interaction with the ambient. This
+paper gives the results of density functional calculations of the strain
+components orthogonal to crystal surface in a number of configurations likely
+found in real samples.",1412.3301v1
+2014-12-16,Gold Nanoparticles supported on MoS2 Nanoribbons matrix as a biocompatible and water dispersible platform for enhanced photothermal ablation of cancerous cells using harmless near infrared irradiation,"With photothermal efficiency higher than traditionally used reduced graphene
+oxide, while simultaneously being water dispersible, we propose biocompatible
+Molybdenum Nanoribbons - gold Nanoparticles (MoS2 NR-Au NPs) system for
+synergistically enhanced photo-thermal ablation of cancerous cells (100%
+fatality) using NIR radiation (808nm), owing to commendable temperature rise
+above 70oC at a much faster rate.",1412.4943v1
+2014-12-24,Seaborg's Plutonium?,"Passive x-ray and gamma-ray analysis was performed on UC Berkeley's EH&S
+Sample S338. The object was found to contain Pu-239 and no other radioactive
+isotopes. The mass of Pu-239 contained in this object was determined to be 2.0
++- 0.3 micrograms. These observations are consistent with the identification of
+this object being the 2.77-microgram plutonium oxide sample described by Glenn
+Seaborg and his collaborators as the first sample of Pu-239 that was large
+enough to be weighed.",1412.7590v2
+2014-12-26,Screened exchange dynamical mean field theory and its relation to density functional theory: SrVO3 and SrTiO3,"We present the first application of a recently proposed electronic-structure
+scheme to transition metal oxides: screened exchange dynamical mean-field
+theory includes non-local exchange beyond the local density approximation and
+dynamical correlations beyond standard dynamical mean-field theory. Our results
+for the spectral function of SrVO3 are in agreement with the available
+experimental data, including photoemission spectroscopy and thermodynamics.
+Finally, the 3d0 compound SrTiO3 serves as a test case to illustrate how the
+theory reduces to the band structure of standard electronic-structure
+techniques for weakly correlated compounds.",1412.7971v1
+2014-12-29,Molecular theory of graphene chemical modification,"The chapter is devoted to chemical uniqueness of graphene. In view of
+molecular theory, the latter is a consequence of benzenoid packing of carbon
+atoms, based on three neighbors to each carbon atom leaving the atom fourth
+valence electron (the odd one) on its own. Due to rather large C-C distances,
+the odd electrons of graphene molecules are correlated whereupon the molecules
+are radicalized and molecular chemistry of graphene is the chemistry of
+dangling bonds. The chapter presents the description of the
+molecular-theory-dangling-bond view on graphene molecule hydrogenation and
+oxidation. Specific peculiarities of the graphene molecular chemistry related
+to size-dependent topochemical features are discussed, as well",1412.8306v1
+2015-01-13,Intense femtosecond photoexcitation of bulk and monolayer MoS2,"The effect of femtosecond laser irradiation on bulk and single-layer MoS2 on
+silicon oxide is studied. Optical, Field Emission Scanning Electron Microscopy
+(FESEM) and Raman microscopies were used to quantify the damage. The intensity
+of A1g and E2g1 vibrational modes was recorded as a function of the number of
+irradiation pulses. The observed behavior was attributed to laser-induced bond
+breaking and subsequent atoms removal due to electronic excitations. The
+single-pulse optical damage threshold was determined for the monolayer and bulk
+under 800nm and 1030nm pulsed laser irradiation and the role of two-photon
+versus one photon absorption effects is discussed.",1501.02929v1
+2015-01-14,Exact double-counting in combining the Dynamical Mean Field Theory and the Density Functional Theory,"We propose a continuum representation of the Dynamical Mean Field Theory, in
+which we were able to derive an exact overlap between the Dynamical Mean Field
+Theory and band structure methods, such as the Density Functional Theory. The
+implementation of this exact double-counting shows improved agreement between
+theory and experiment in several correlated solids, such as the transition
+metal oxides and lanthanides. Previously introduced nominal double-counting is
+in much better agreement with the exact double-counting than most widely used
+fully localized limit formula.",1501.03438v1
+2015-01-21,Many-Body electronic structure calculations of Eu doped ZnO,"The formation energies and electronic structure of europium doped zinc oxide
+has been determined using DFT and many-body $GW$ methods. In the absence of
+intrisic defects we find that the europium-$f$ states are located in the ZnO
+band gap with europium possessing a formal charge of 2+. On the other hand, the
+presence of intrinsic defects in ZnO allows intraband $f-f$ transitions
+otherwise forbidden in atomic europium. This result coorroborates with recently
+observed photoluminescence in the visible red region [1].",1501.05090v2
+2015-01-31,Tuning Optical Properties of Transparent Conducting Barium Stannate by Dimensional Reduction,"We report calculations of the electronic structure and optical properties of
+doped $n$-type perovskite BaSnO3 and layered perovskites. While doped BaSnO$_3$
+retains its transparency for energies below the valence to conduction band
+onset, the doped layered compounds exhibit below band edge optical conductivity
+due to transitions from the lowest conduction band. This gives absorption in
+the visible for Ba2SnO4. Thus it is important to minimize this phase in
+transparent conducting oxide (TCO) films. Ba3Sn2O7 and Ba4Sn3O10 have strong
+transitions only in the red and infrared, respectively. Thus there may be
+opportunities for using these as wavelength filtering TCO.",1502.00171v1
+2015-02-02,Electromechanical properties of freestanding graphene functionalized with tin oxide (SnO2) nanoparticles,"Freestanding graphene membranes were functionalized with SnO2 nanoparticles.
+A detailed procedure providing uniform coverage and chemical synthesis is
+presented. Elemental composition was determined using scanning electron
+microscopy combined with energy dispersive X-ray analysis. A technique called
+electrostatic-manipulation scanning tunneling microscopy was used to probe the
+electromechanical properties of functionalized freestanding graphene samples.
+We found ten times larger movement perpendicular to the plane compared to
+pristine freestanding graphene, and propose a nanoparticle encapsulation model.",1502.00613v1
+2015-02-03,Persistent ion beam induced conductivity in zinc oxide nanowires,"We report persistently increased conduction in ZnO nanowires irradiated by
+ion beam with various ion energies and species. This effect is shown to be
+related to the already known persistent photo conduction in ZnO and dubbed
+persistent ion beam induced conduction. Both effects show similar excitation
+efficiency, decay rates, and chemical sensitivity. Persistent ion beam induced
+conduction will potentially allow countable (i.e., single dopant) implantation
+in ZnO nanostructures and other materials showing persistent photo conduction.",1502.00828v1
+2015-02-12,Impact of Ferroelectric Distortion on Thermopower in BaTiO3,"We present a strategy for increasing thermoelectric performance by invoking
+ferroelectric distortion in a transition-metal oxide. By using an ab initio
+calculation approach with the Boltzmann transport equation, a large Seebeck
+coefficient is calculated in n-type BaTiO3. The polar structural distortion
+causes the peculiar dispersion of the lowest conduction band, which enhances
+the Seebeck coefficient along the polar direction. A microscopic mechanism of
+carrier concentration dependence of the Seebeck coefficient is discussed in
+terms of the band velocity distribution in the Brillouin zone.",1502.03525v1
+2015-03-07,Ricci-flat spacetimes admitting higher rank Killing tensors,"Ricci-flat spacetimes of signature (2,q) with q=2,3,4 are constructed which
+admit irreducible Killing tensors of rank-3 or rank-4. The construction relies
+upon the Eisenhart lift applied to Drach's two-dimensional integrable systems
+which is followed by the oxidation with respect to free parameters. In four
+dimensions, some of our solutions are anti-self-dual.",1503.02162v1
+2015-03-07,Synthesis and characterization of vertically oriented hybrid Zn2GeO4-ZnO beaded nanowire arrays and Zn2GeO4 nanotubes,"Vertically aligned, beaded zinc germinate (Zn2GeO4)/ zinc oxide (ZnO) hybrid
+nanowire arrays were successfully synthesized by a vapor-solid process via a
+catalyst-free approach. The as-synthesized products were characterized using
+X-ray diffraction, scanning electron microscopy and transmission electron
+microscopy equipped with an energy-dispersive X-ray spectrometer. TEM studies
+revealed the beaded microstructures of the Zn2GeO4/ZnO nanowire. Furthermore,
+Zn2GeO4 nanotubes were synthesized after wet etching treatments on Zn2GeO4/ZnO
+hybrid nanowires.",1503.02201v1
+2015-03-09,Fluidic Integration of Nanophotonic Devices Using Decomposable Polymers,"Polynorbornene-based decomposable polymer which can be patterned with
+ultraviolet or electron-beam radiation is used to create micrometer-scale
+fluidic channels. Silicon nitride substrates are used to fabricate nanophotonic
+wavegide and resonators operating in the visible range of the spectrum. Fluidic
+channels generated by thermally decomposing the polymer through the oxide
+cladding is used to deliver ultra-small amounts of florescent samples to the
+optical sensors.",1503.02631v1
+2015-03-26,Emergent Transition for Superconducting Fluctuations in Antiferromagnetic Ruthenocuprates,"The emergence of carrier-pairing from the electronically inhomogeneous phase
+of lightly hole-doped copper oxides has been investigated through
+magnetoresistance measurements on 1222-type ruthenocuprates
+RuSr2(R,Ce)2Cu2O10-d, principally with R = Gd, Sm, Nd. A well-defined
+transition at which superconducting fluctuations emerge is discovered at a
+remarkably low critical doping, pc = 0.0084, deep within the antiferromagnetic
+phase. Systematic variations of the low temperature fluctuation density with
+doping and cell volume demonstrate the intrinsic nature of the electronic
+inhomogeneity and provide new support for bosonic models of the superconducting
+mechanism.",1503.07714v1
+2015-04-16,Coupling ferroelectricity with spin-valley physics in oxide-based heterostructure,"The coupling of spin and valley physics is nowadays regarded as a promising
+route toward next-generation spintronic and valleytronic devices. In the aim of
+engineering functional properties for valleytronic applications, we focus on
+the ferroelectric heterostructure BiAlO3/BiIrO3, where the complex interplay
+among trigonal crystal field, layer degrees of freedom and spin-orbit coupling
+mediates a strong spin-valley coupling. Furthermore, we show that
+ferroelectricity provides a non-volatile handle to manipulate and switch the
+emerging valley-contrasting spin polarization.",1504.04091v1
+2015-04-17,Synthesis of titanium-oxide nanoparticles with size and stoichiometry control,"Ti-O nanoparticles have been synthesized via hollow cathode sputtering in an
+Ar-O2 atmosphere using high power pulsing. It is shown that the stoichiometry
+and the size of the nanoparticles can be varied independently, the former
+through controlling the O2 gas flow and the latter by the independent biasing
+of two separate anodes in the growth zone. Nanoparticles with diameters in the
+range of 25 to 75 nm, and with different Ti-O compositions and crystalline
+phases, have been synthesized.",1504.04458v1
+2015-05-16,An Updated Wing TiO Sensitive Index for Classification of M-Type Stars,"By careful searching of synthetic and observed spectra in a sample of cool
+giant and supergiant stars, we have updated the continuum band-passes of
+near-infrared Wing three filter system. This photometric system measures the
+strength of Titanium Oxide (TiO) absorption in Near-Infrared (NIR) at 719 nm.
+We show that new reference continuum band-passes are essentially free from
+molecular absorptions and the updated TiO-index defines the temperature
+variation in a sample of cool giants with less scatter. A TiO-index vs.
+effective temperature calibration is derived based on new continuum
+band-passes.",1505.04332v1
+2015-05-28,Intrinsic spin Hall effect in systems with striped spin-orbit coupling,"The Rashba spin-orbit coupling arising from structure inversion asymmetry
+couples spin and momentum degrees of freedom providing a suitable (and very
+intensively investigated) environment for spintronic effects and devices. Here
+we show that in the presence of strong disorder, non-homogeneity in the
+spin-orbit coupling gives rise to a finite spin Hall conductivity in contrast
+with the corresponding case of a homogeneous linear spin-orbit coupling. In
+particular, we examine the inhomogeneity arising from a striped structure for a
+two-dimensional electron gas, affecting both density and Rashba spin-orbit
+coupling. We suggest that this situation can be realized at oxide interfaces
+with periodic top gating.",1505.07667v1
+2015-06-03,Calculation method of spin accumulations and spin signals in nanostructures using spin resistors,"The understanding and calculation of spin transport are essential elements
+for the development of spintronics devices. Here, we propose a simple method to
+calculate analytically the spin accumulations, spin currents and
+magnetoresistances in complex systems. This can be used both for CPP
+experiments in multilayers and for multiterminal nanostructures made of
+semiconductors, oxides, metals and carbon allotropes.",1506.01347v2
+2015-07-23,Field-effect induced tunability in planar hyperbolic metamaterials,"We demonstrate that use of the field effect to tune the effective optical
+parameters of a layered hyperbolic metamaterial leads to topological
+transitions in its dispersion characteristics in the optical regime. Field
+effect gating electrically modulates the permittivity in transparent conductive
+oxides via changes in the carrier density. These permittivity changes lead to
+active extreme modulation of ~200% of the effective electromagnetic parameters
+along with active control of the anisotropic dispersion surface of hyperbolic
+metamaterials and enable the opening and closing of photonic band gaps.",1507.06645v1
+2015-10-07,Atomic layer deposition of Y2O3 on h-BN for a gate stack in graphene FETs,"The combination of h-BN and high-k dielectrics is required for a top gate
+insulator in miniaturized graphene field-effect transistors because of the low
+dielectric constant of h-BN. We investigated the deposition of Y2O3 on h-BN
+using atomic layer deposition. The deposition of Y2O3 on h-BN was confirmed
+without any buffer layer. An increase in the deposition temperature reduced the
+surface coverage. The deposition mechanism could be explained by the
+competition between the desorption and adsorption of the Y precursor on h-BN
+due to the polarization. Although a full surface coverage was difficult to
+achieve, the use of an oxidized metal seeding layer on h-BN resulted in a full
+surface coverage.",1510.01928v1
+2015-11-12,Simulation of Enhancement Mode GaN HEMTs with Threshold > 5 V using P-type Buffer,"A high threshold voltage enhancement-mode GaN HEMT with p-type doped buffer
+is discussed and simulated. Analytical expressions are derived to explain the
+role of buffer capacitance in designing and enhancing threshold voltage.
+Simulations of the proposed device with p-type buffer show threshold voltages
+above 5 V, and a positive shift in threshold voltage as the oxide capacitance
+is reduced, thus enabling threshold voltage tunability over an unprecedented
+range for GaN-based HEMTs. The electric field profiles, breakdown performance,
+on-resistance and delay tradeoffs in the proposed pGaN back HEMT device are
+also discussed.",1511.04438v1
+2015-11-23,Metallic interface in non-SrTiO3 based titanate superlattice,"We report on the fabrication of all perovskite Mott insulator/band insulator
+YTiO3/CaTiO3 superlattices by pulsed laser deposition. The combination of in
+situ reflection high energy electron diffraction, X-ray diffraction, and X-ray
+reflectivity confirms the high quality of the films grown in a layer-by-layer
+mode. Electrical transport measurements reveal that a non-SrTiO3 based two
+dimensional electron gas system has formed at the YTiO3/CaTiO3 interface. These
+studies offer another route in the pursuit of complex oxide two-dimensional
+electron gas systems, which allows to obtain greater insights into the exotic
+many-body phenomena at such interfaces.",1511.07484v1
+2016-01-01,Reverse degradation of nickel graphene junction by hydrogen annealing,"Metal contacts are fundamental building components for graphene based
+electronic devices and their properties are greatly influenced by interface
+quality during device fabrication, leading to resistance variation. Here we
+show that nickel graphene junction degrades after air exposure, due to
+interfacial oxidation, thus creating a tunneling barrier. Most importantly, we
+demonstrate that hydrogen annealing at moderate temperature (300 0C) is an
+effective technique to reverse the degradation.",1601.00109v2
+2016-01-08,Persistence weighted Gaussian kernel for topological data analysis,"Topological data analysis (TDA) is an emerging mathematical concept for
+characterizing shapes in complex data. In TDA, persistence diagrams are widely
+recognized as a useful descriptor of data, and can distinguish robust and noisy
+topological properties. This paper proposes a kernel method on persistence
+diagrams to develop a statistical framework in TDA. The proposed kernel
+satisfies the stability property and provides explicit control on the effect of
+persistence. Furthermore, the method allows a fast approximation technique. The
+method is applied into practical data on proteins and oxide glasses, and the
+results show the advantage of our method compared to other relevant methods on
+persistence diagrams.",1601.01741v2
+2016-01-15,Decoherence and Decay of Two-level Systems due to Non-equilibrium Quasiparticles,"It is frequently observed that even at very low temperatures the number of
+quasiparticles in superconducting materials is higher than predicted by
+standard BCS-theory. These quasiparticles can interact with two-level systems,
+such as superconducting qubits or two-level systems (TLS) in the amorphous
+oxide layer of a Josephson junction. This interaction leads to decay and
+decoherence of the TLS, with specific results, such as the time dependence,
+depending on the distribution of quasiparticles and the form of the
+interaction. We study the resulting decay laws for different experimentally
+relevant protocols.",1601.03861v1
+2016-01-18,Investigation of ITO based liquid sensor for ammonia hydroxide detection,"We proposed an Indium Tin Oxide (ITO) sensor for detecting the NH4OH in
+seawater and carried out a series of experiments to investigate the feasibility
+of it as a hazardous and noxious substance (HNS) sensor. The ITO layer revealed
+a distinct resistance change ({\delta}R) which is linearly correlated with the
+NH4OH concentration. Sensing mechanism of the porous ITO layer has been
+explained in terms of reduction and electrical double layer (EDL) formation.
+Also, the chemical stability of ITO as a HNS sensor has verified.",1601.04446v1
+2016-03-11,Reconfigurable quadruple quantum dots in a silicon nanowire transistor,"We present a novel reconfigurable metal-oxide-semiconductor multi-gate
+transistor that can host a quadruple quantum dot in silicon. The device consist
+of an industrial quadruple-gate silicon nanowire field-effect transistor.
+Exploiting the corner effect, we study the versatility of the structure in the
+single quantum dot and the serial double quantum dot regimes and extract the
+relevant capacitance parameters. We address the fabrication variability of the
+quadruple-gate approach which, paired with improved silicon fabrication
+techniques, makes the corner state quantum dot approach a promising candidate
+for a scalable quantum information architecture.",1603.03636v1
+2016-03-20,Oxygen Channels and Fractal Wave-Particle Duality in the Evolution of Myoglobin and Neuroglobin,"The evolution of terrestrial and aquatic wild type (WT) globins is dominated
+by changes in two proximate - distal Histidine ligand exit channels, here
+monitored quantitatively by hydropathic waves. These waves reveal allometric
+functional features inaccessible to single amino acid stereochemical contact
+models, and even very large all-atom Newtonian simulations. The evolutionary
+differences between these features between myoglobin and neuroglobin are
+related to the two oxidation channels through hydropathic wave analysis, which
+identifies subtle interspecies functional differences inaccessible to
+traditional size and metabolic scaling studies. Our analysis involves dynamic
+synchronization of allometric interactions across entire globins.",1603.06219v1
+2016-03-21,Improved Optimization for the Cluster Jastrow Antisymmetric Geminal Power and Tests on Triple-Bond Dissociations,"We present a novel specialization of the variational Monte Carlo linear
+method for the optimization of the recently introduced cluster Jastrow
+antisymmetric geminal power ansatz, achieving a lower-order polynomial cost
+scaling than would be possible with a naive application of the linear method
+and greatly improving optimization performance relative to the previously
+employed quasi-Newton approach. We test the methodology on highly
+multi-reference triple-bond stretches, achieving accuracies superior to
+traditional coupled cluster theory and multi-reference perturbation theory in
+both the typical example of N$_2$ and the transition-metal-oxide example of
+[ScO]$^+$.",1603.06605v1
+2016-04-05,Global sensitivity analysis of battery equivalent circuit model parameters,"This paper considers one of the most commonly used equivalent circuit models
+(ECMs) for lithium-ion batteries and investigates the sensitivity of the model
+output to changes of model parameters using the Morris method. Experiments are
+carried out on a lithium-ion cell with nickel manganese cobalt oxide (NMC)
+electrode and parameters of the model are identified in the state of charge
+(SOC) range [100%,10%]. Although all the model parameters do vary with SOC,
+global sensitivity analysis reveals that the uncertainties of some of the
+parameters generate very little uncertainty in the voltage output, implying
+that those parameters can be taken as constants without compromising the
+accuracy of the model. This is further confirmed by experimental validation.",1604.01293v1
+2016-04-20,Positive electron affinity of interfacial region in Polyethylene-MgO nanocomposite dielectric,"Polymer-based nanocomposite dielectrics are expected to become essential in
+future generations of high voltage electrical insulation. However, the physics
+behind their performance is not yet understood. Here we investigate electronic
+properties of the interfacial area in magnesium oxide-polyethylene
+nanocomposite. We use density functional theory to calculate densities of
+states for MgO (100) and hydroxylated MgO (111) interfaces with polyethylene.
+We evaluate the role of silicon-based nanoparticle surface modification at the
+electronic level and propose a new theory for charge trapping in
+nanocomposites.",1604.05984v2
+2016-06-21,Proposal for a spin MOSFET based on spin gapless semiconductors,"We propose a spintronic metal oxide semiconductor field effect transistor
+(spin MOSFET) where a spin gapless semiconductor (SGS) constitutes the channel
+and the drain is a ferromagnetic metal. SGS exhibit a non-zero band gap in only
+one of the spin sub-bands and feature complete spin polarization at finite
+temperature. We present an analytical model of the device and comment the
+properties relevant for devices applications. Our results boost SGS as a new
+paradigm for the spin MOSFET concept.",1606.06445v1
+2016-07-09,"Variation of the physical properties of four transition metal oxides SrTMO3 (TM = Rh, Ti, Mo, Zr) under pressure: An ab initio study","Using first principles calculations, we have studied the structural and
+elastic properties of SrTMO3 (TM = Rh, Ti, Mo, Zr) under pressure by the plane
+wave pseudopotential method based on the density functional theory (DFT) within
+the generalized gradient approximation (GGA). The optical properties have been
+investigated under zero pressure. It is observed that the calculated lattice
+parameters are in good agreement with the available experimental result and
+previous theoretical results.",1607.02592v1
+2016-07-27,Interference-based molecular transistors,"Molecular transistors have the potential for switching with lower gate
+voltages than conventional field-effect transistors. We have calculated the
+performance of a single-molecule device in which there is interference between
+electron transport through the highest occupied molecular orbital and the
+lowest unoccupied molecular orbital of a single molecule. Quantum interference
+results in a subthreshold slope that is independent of temperature. For
+realistic parameters the change in gate potential required for a change in
+source-drain current of two decades is 20 mV, which is a factor of six smaller
+than the theoretical limit for a metal-oxide-semiconductor field-effect
+transistor.",1607.07998v1
+2016-09-14,Graphical analysis of Current-Voltage Characteristics in Typical Memristive Interfaces,"A graphical representation based on the isothermal current-voltage (IV)
+measurements of typical memristive interfaces is presented. This is the
+starting point to extract relevant microscopic information of the parameters
+that control the electrical properties of a device based on a particular
+metal-oxide interface. The convenience of the method is illustrated presenting
+some examples were the IV characteristics were simulated in order to gain
+insight on the influence of the fitting parameters.",1609.04472v3
+2016-10-14,A local Fock-exchange potential in Kohn-Sham equations,"We derive and employ a local potential to represent the Fock exchange
+operator in electronic single-particle equations. This local Fock-exchange
+(LFX) potential is very similar to the exact exchange (EXX) potential in
+density functional theory (DFT). The practical software implementation of the
+two potentials (LFX and EXX) yields robust and accurate results for a variety
+of systems (semiconductors, transition metal oxides) where Hartree Fock and
+popular approximations of DFT typically fail. This includes examples
+traditionally considered qualitatively inaccessible to calculations that omit
+correlation.",1610.04363v1
+2016-10-17,Role of nonlinearity in resistive switching phenomena of lanthanum calcium manganate heterostructures,"The present paper examines the influence of a nonlinear relationship between
+the local oxygen-vacancy concentration and the local resistivity on resistive
+switching effects in complex oxides. The continuity equation has been used as a
+model for the motion of oxygen vacancies when a periodic time-dependent
+electrical current is applied. The question of endurance of the switching
+cycles is discussed. It is found that nonlinearity of the
+resistivity-concentration dependence enhances the endurance.",1610.05194v1
+2016-10-25,"Interface structure, band alignment and built-in potentials at LaFeO$_3$/$\textit{n}$-SrTiO$_3$ heterojunctions","Interface structure at polar/non-polar interfaces has been shown to be a key
+factor in controlling emergent behavior in oxide heterostructures, including
+the LaFeO$_3$/$\textit{n}$-SrTiO$_3$ system. We demonstrate via high energy
+resolution x-ray photoemission that epitaxial LaFeO$_3$/$\textit{n}$-SrTiO$_3$
+(001) heterojunctions engineered to have opposite interface polarities exhibit
+very similar band offsets and potential gradients within the LaFeO$_3$ films.
+However, differences in the potential gradient within the SrTiO$_3$ layer
+depending on polarity may promote hole diffusion into LaFeO$_3$ for
+applications in photocatalysis.",1610.08113v1
+2017-02-04,Single-photon source based on Rydberg exciton blockade,"We propose to implement a new kind of solid-state single-photon source based
+on the recently observed Rydberg blockade effect for excitons in cuprous oxide.
+The strong interaction between excitons in levels with high principal quantum
+numbers prevents the creation of more than one exciton in a small crystal. The
+resulting effective two-level system is a good single-photon source. Our
+quantitative estimates suggest that GHz rates and values of the second-order
+correlation function $g_2(0)$ below the percent level should be simultaneously
+achievable.",1702.01213v1
+2017-02-14,Hidden radical reactivity of the [FeO]2+ group of the (hydro)oxide species in the H-abstraction from methane: a DFT and CASPT2 study,"Reactivity of the [FeO]2+ group in the abstraction of hydrogen from methane
+is determined by metastable oxyl state FeIII-O* causing the negative spin
+polarization of the methyl moiety as was shown by quantum-chemical means with
+the use of model iron hydroxide species FeO(OH)2, Fe2O(OH)5, and Fe4O5(OH)3 as
+an example.",1702.04092v1
+2017-02-23,Dynamics in poly(propylene glycol) and silica oxide nanoparticles composite glassforming system,"Results of broadband dielectric spectroscopy and rheological studies of
+poly(propylene glycol) + SiO${_2}$ nanocomposites are presented. They show that
+the dynamics in high-concentrated composite is determined by confinement and
+adsorption effects, resulting from interactions of confined polymers correspond
+with the host system at the interface between PPG and solid nanoparticles. The
+evolution of relaxation times follows the clear Vogel-Fulcher-Tammann pattern,
+what is proved by the supplementary activation energy temperature index
+analysis. The strong influence of nanoparticles on the transitional dynamics
+and the fragility in the ultraviscous domain was noted.",1702.07280v1
+2017-02-28,Conductance oscillations in graphene/nanoclusters hybrid material: towards large area single electron devices,"Large assemblies of self-organized aluminum nanoclusters embedded in an oxide
+layer are formed on graphene templates and used to build tunnel-junction
+devices. Unexpectedly, single-electron-transport behavior with well-defined
+Coulomb oscillations is observed for a record junction area containing millions
+of metal islands. Such hybrid materials offer new prospects for single-electron
+electronics.",1703.00067v1
+2017-03-25,Real-space analysis of scanning tunneling microscopy topography datasets using sparse modeling approach,"A sparse modeling approach is proposed for analyzing scanning tunneling
+microscopy topography data, which contains numerous peaks corresponding to
+surface atoms. The method, based on the relevance vector machine with
+$\mathrm{L}_1$ regularization and $k$-means clustering, enables separation of
+the peaks and atomic center positioning with accuracy beyond the resolution of
+the measurement grid. The validity and efficiency of the proposed method are
+demonstrated using synthetic data in comparison to the conventional
+least-square method. An application of the proposed method to experimental data
+of a metallic oxide thin film clearly indicates the existence of defects and
+corresponding local lattice deformations.",1703.08643v1
+2017-08-23,Orbital Physics,"A tutorial introduction into the principles of Orbital Physics in strongly
+correlated transition metal oxides.",1708.07183v1
+2018-02-06,Exploring the energy landscape of resistive switching in antiferromagnetic Sr(3)Ir(2)O(7),"We study the resistive switching triggered by an applied electrical bias in
+antiferromagnetic Mott insulator Sr(3)Ir(2)O(7). The switching was previously
+associated with an electric-field driven structural transition. Here we use
+time-resolved measurements of the switching to probe the energy barrier
+associated with the transition. We quantify the changes in the energy barrier
+height with respect to the applied bias and find a linear decrease of the
+barrier with increasing bias. Our observations support the potential of
+antiferromagnetic transition metal oxides for spintronic applications.",1802.01923v1
+2018-02-25,Spatial-resolved X-ray photoelectron spectroscopy of Weyl semimetal NbAs,"We utilized X-ray photoemission electron microscopy (XPEEM) and X-ray
+photoelectron spectroscopy (XPS) to investigate the crystal surface of Weyl
+semimetal NbAs. XPEEM images present white and black contrast in both the Nb 3d
+and As 3d core level spectra. Surface-sensitive XPS spectra indicate that the
+entire surface of the sample contains both surface states of Nb 3d and As 3d,
+in form of oxides, and bulk states of NbAs. Estimated atomic percentage values
+nNb/nAs suggest that the surface is Nb-rich and asymmetric for white and black
+areas.",1802.08978v1
+2018-02-26,2D materials coated plasmonic structures for SERS applications,"Two-dimensional (2D) materials, such as graphene and hexagonal boron nitride,
+are new kind of materials that can serve as substrates for surface enhanced
+Raman spectroscopy (SERS). When combined with traditional metallic plasmonic
+structures, the hybrid 2D materials/metal SERS platform brings extra benefits,
+including higher SERS enhancement factors, oxidation protection of metal
+surface, and protection of molecules from photo-induced damage. This
+perspective gives an overview of recent progress in 2D materials coated
+plasmonic structure in SERS application. This paper focuses on the fabrication
+of the hybrid 2D materials/metal SERS platform and their applications for Raman
+enhancement.",1802.09939v1
+2018-04-24,Novel Highly Active Pt/Graphene Catalyst for Cathodes of Cu(II/I)-Mediated Dye-Sensitized Solar Cells,"Novel highly active, optically-transparent electrode catalyst containing Pt,
+PtOx, graphene oxide and stacked graphene platelet nanofibers is developed for
+a cathode of Cu(II/I)-mediated dye-sensitized solar cells.",1804.09119v1
+2018-11-19,Photovoltaic effect in multi-domain ferroelectric perovskite oxides,"We propose a device model that elucidates the role of domain walls in the
+photovoltaic effect in multi-domain ferroelectric perovskites. The model
+accounts for the intricate interplay between ferroelectric polarization, space
+charges, photo-generation and electronic transport. When applied to bismuth
+ferrite, results show a significant electric potential step across both
+71-degree and 109-degree domain walls, which in turn contributes to the
+photovoltaic (PV) effect. We also find a strong correlation between
+polarization and oxygen octahedra tilts, which indicates the nontrivial role of
+the latter in the PV effect. The domain wall-based PV effect is further shown
+to be additive in nature, allowing for the possibility of generating
+above-bandgap voltage",1811.07948v1
+2019-05-01,Degenerately Doped Transition Metal Dichalcogenides as Ohmic Homojunction Contacts to Transition Metal Dichalcogenide Semiconductors,"In search of an improved strategy to form low resistance contacts to MoS2 and
+related semiconducting transition metal dichalcogenides, we use ab initio
+density functional electronic structure calculations in order to determine the
+equilibrium geometry and electronic structure of MoO3/MoS2 and MoO2/MoS2
+bilayers. Our results indicate that, besides a rigid band shift associated with
+charge transfer, the presence of molybdenum oxide modifies the electronic
+structure of MoS2 very little. We find that the charge transfer in the bilayer
+provides a sufficient degree of hole doping to MoS2, resulting in a highly
+transparent contact region.",1905.00285v1
+2019-05-21,Interseries transitions between Rydberg excitons in Cu$_{\mathrm{2}}$O,"We investigate the infrared optical transitions between excitons of the
+yellow, green and blue series in the cuprous oxide Cu$_{\mathrm{2}}$O. We show
+that in many cases the dipole approximation is inadequate and, in particular,
+that it breaks down in yellow-blue transitions even for moderate principal
+quantum numbers of $n \approx 10$. The interband matrix elements of the
+transition operator needed for the evaluation of the excitonic transition
+strengths are derived from known as well as from fitted band parameters.",1905.08752v2
+2020-07-06,Interface evolution in phase transformation ruled by nucleation and growth,"An analytical model for the evolution of the boundary of the new phase in
+transformations ruled by nucleation and growth is presented. Both homogeneous
+and heterogeneous nucleation have been considered: The former includes
+transformations in 2D and 3D space and the latter nucleation and growth on flat
+solid substrate. The theory is formulated for the general case of spatially
+correlated nuclei, arbitrary nucleation rate and power growth law of nuclei. In
+the case of heterogeneous nucleation, spheroidal nuclei have been assumed and
+the dependence of the kinetics on contact angle investigated. The validity of
+the present approach is deemed through comparison with experimental data from
+literature which also comprise oxide growth by ALD (Atomic Layer Deposition)
+metal electrodeposition at solid substrate and alloy recrystallization.",2007.02700v1
+2020-07-12,Reconstruction of 3D Image of Nanorice Particle from Randomly Oriented Single-Shot Experimental Diffraction Patterns Using Angular Correlation Method,"We reconstructed intensities in Fourier space and electron densities in the
+real space for an azimuthally symmetric object Nanorice particle (Iron Oxide
+nanoparticle) exposed in the ultrashort, bright and coherent x-ray free
+electron laser (XFEL) pulses with random unknown orientations through the
+method of angular correlations among intensities appeared in ninety eight 2D
+diffraction patterns collected at Linac Coherent Light Source (LCLS).",2007.06030v1
+2020-07-16,Piezoelectric SPDT NEMS Switch for Complementary Logic,"Off-state current leakage and switching delay has become the main challenge
+for continued complementary metal-oxide-semiconductor (CMOS) technology
+scaling. Previous work proposes a ""see-saw"" relay structure to mimic the
+operation of CMOS. This paper presents a novel single-pole double-throw (SPDT)
+switch structure based on AlN piezoelectric cantilever beam to improve the
+former ""see-saw"" relay structure. Geometry parameters are given and key switch
+parameters such as actuation voltage, switching time and contact force have
+been calculated and compared with previous ""see-saw"" relay structure. Analysis
+and design process is shown and micro-fabrication process is described as well.",2007.08134v1
+2010-05-06,Diodes with Breakdown Voltages Enhanced by the Metal-Insulator Transition of LaAlO$_3$-SrTiO$_3$ Interfaces,"Using the metal-insulator transition that takes place as a function of
+carrier density at the LaAlO$_3$-SrTiO$_3$ interface, oxide diodes have been
+fabricated with room-temperature breakdown voltages of up to 200 V. With
+applied voltage, the capacitance of the diodes changes by a factor of 150. The
+diodes are robust and operate at temperatures up to 270 C.",1005.0941v1
+2010-05-09,Piezoelectricity in the dielectric component of nanoscale dielectric/ferroelectric superlattices,"The origin of the functional properties of complex oxide superlattices can be
+resolved using time-resolved synchrotron x-ray diffraction into contributions
+from the component layers making up the repeating unit. The CaTiO3 layers of a
+CaTiO3/BaTiO3 superlattice have a piezoelectric response to an applied electric
+field, consistent with a large continuous polarization throughout the
+superlattice. The overall piezoelectric coefficient at large strains, 54 pm/V,
+agrees with first-principles predictions in which a tetragonal symmetry is
+imposed on the superlattice by the SrTiO3 substrate.",1005.1430v1
+2010-05-10,Internal structure of nanoparticles of Al generated by laser ablation in liquid ethanol,"Al NPs are synthesized by laser ablation of a bulk Al target immersed into
+liquid ethanol saturated with hydrogen at atmospheric pressure. The
+nanoparticles possess a well-distinguished core-shell structure. High
+Resolution Transmission Electron Microscopy shows several layers inside the Al
+nanoparticle: oxide layer, amorphous Al, single crystal Al, and a cavity in the
+center. Formation of the cavity is attributed to the sharp increase of hydrogen
+dissolution in Al upon its melting and its eventual release after the
+solidification.",1005.1461v1
+2010-05-10,Orbital order and possible superconductivity in LaNiO3/LaMO3 superlattices,"A hypothetical layered oxide La_2NiMO_6 where NiO_2 and MO_2 planes alternate
+along the c-axis of ABO_3 perovskite lattice is considered theoretically. Here,
+M denotes a trivalent cation Al, Ga,... such that MO_2 planes are insulating
+and suppress the c-axis charge transfer. We predict that correlated e_g
+electrons in the NiO_2 planes develop a planar x^2-y^2 orbital order driven by
+the reduced dimensionality and further supported by epitaxial strain from the
+substrate. Low energy electronic states can be mapped to a single-band t-t'-J
+model, suggesting favorable conditions for high-T_c superconductivity.",1005.1464v1
+2010-05-31,S-shaped current-voltage characteristics of organic solar devices,"Measuring the current-voltage characteristic of organic bulk heterojunction
+solar devices sometimes reveals an s-shaped deformation. We qualitatively
+produce this behaviour by a numerical device simulation assuming a reduced
+surface recombination. Furthermore we show how to experimentally create these
+double diodes by applying an oxygen plasma etch on the indium tin oxide (ITO)
+anode. Restricted charge transport over material interfaces accumulates space
+charges and therefore creates s-shaped deformations. Finally we discuss the
+consequences of our findings for the open circuit voltage $V_{oc}$",1005.5669v2
+2013-08-07,Electrochemical Grafting of Naphthylmethyl Radicals to Epitaxial Graphene: A Versatile Platform to Reversibly Engineer the Band Structure and Transport Properties of Graphene,"The Kolbe electrochemical oxidation strategy has been utilized to achieve an
+efficient quasireversible electrochemical grafting of the alpha-naphthylmethyl
+functional group to graphene. The method facilitates reversible bandgap
+engineering in graphene and preparation of electrochemically erasable organic
+dielectric films. The picture shows Raman D-band maps of both systems.",1308.1645v1
+2013-08-30,Graphene Nanotechnology for the Next Generation Nonvolatile Memory,"As conventional silicon technology is approaching its fundamental material
+and physical limits with continuous scaling, there is a growing push to look
+for new platform to design memory circuits for nanoelectronic applications. In
+this paper we explore new design concept of nonvolatile memory based on
+graphene nanotechnology. The investigation focuses on two forms of graphene
+based field effect transistor (FET) carbon nanotube FET (CNTFET) and graphene
+nanoribbon FET (GNRFET). The analysis reveals that GNRFET with a high trapping
+capable oxide layer is suitable for ultra high ensity nonvolatile memory.",1308.6782v1
+2014-03-06,Single photon emission from ZnO nanoparticles,"Room temperature single photon emitters are very important resources for
+photonics and emerging quantum technologies. In this work we study single
+photon emission from defect centers in 20 nm zinc oxide (ZnO) nanoparticles.
+The emitters exhibit bright broadband fluorescence in the red spectral range
+centered at 640 nm with polarized excitation and emission. The studied emitters
+showed continuous blinking, however, bleaching can be suppressed using a
+polymethyl methacrylate (PMMA) coating. Furthermore, hydrogen termination
+increased the density of single photon emitters. Our results will contribute to
+the identification of quantum systems in ZnO.",1403.1301v1
+2016-11-22,"The ALMA-PILS survey: First detections of ethylene oxide, acetone and propanal toward the low-mass protostar IRAS 16293-2422","One of the open questions in astrochemistry is how complex organic and
+prebiotic molecules are formed. Aims. Our aim is to start the process of
+compiling an inventory of oxygen-bearing complex organic molecules toward the
+solar-type Class 0 protostellar binary IRAS16293-2422 from an unbiased spectral
+survey with ALMA (PILS). Here we focus on the new detections of ethylene oxide
+(c-C$_2$H$_4$O), acetone (CH$_3$COCH$_3$), and propanal (C$_2$H$_5$CHO).
+Methods. With ALMA, we surveyed the spectral range from 329 to 363 GHz at
+0.5$""$ (60 AU diameter) resolution. Using a simple model for the molecular
+emission in LTE, the excitation temperatures and column densities of each
+species were constrained. Results. We successfully detect propanal (44 lines),
+ethylene oxide (20 lines) and acetone (186 lines) toward one component of the
+protostellar binary, IRAS16293B. The high resolution maps demonstrate that the
+emission for all investigated species originates from the compact central
+region close to the protostar. This, along with a derived common excitation
+temperature of $\sim$ 125 K, is consistent with a coexistence of these
+molecules in the same gas. Conclusions. The observations mark the first
+detections of acetone, propanal and ethylene oxide toward a low-mass protostar.
+The relative abundance ratios of the two sets of isomers
+(CH$_3$COCH$_3$/C$_2$H$_5$CHO $\sim$ 8 and CH$_3$CHO/c-C$_2$H$_4$O $\sim$ 12)
+are comparable to previous observations toward high-mass protostars. The
+majority of observed abundance ratios from these results as well as those
+measured toward high-mass protostars are up to an order of magnitude above the
+predictions from chemical models. This may reflect either missing reactions or
+uncertain rates in the chemical networks. The physical conditions, such as
+temperatures or densities, used in the models, may not be applicable to
+solar-type protostars either.",1611.07314v1
+2017-01-09,Rupture index: a quantitative measurement of sub-micrometer cracks in graphene,"Per weight graphene is stronger than steel, but because graphene is so thin,
+it breaks and evidently forms cracks during handling, particularly when
+supporting polymers are not used for transfer. In this paper, the parameter
+rupture index is introduced to quantify the density of the cracks and related
+defects in graphene during processing. The approach takes the advantages of the
+high contrast achievable in fluorescence quenching microscopy to distinguish
+between graphene and the background substrate, visible through the cracks in
+graphene. The rupture index can well compare the effectiveness of different
+graphene transferring methods in minimizing the formation of the cracks, and
+quantify the oxidation of metals protected with graphene.",1701.02378v1
+2017-01-25,Rotational state-selection and alignment of chiral molecules by electrostatic hexapoles,"Electrostatic hexapoles are revealed as a powerful tool in the rotational
+state-selection and alignment of molecules to be utilized in beam experiments
+on collisional and photoinitiated processes. In the paper, we report results on
+the application of the hexapolar technique on the recently studied chiral
+molecules propylene oxide, 2-butanol and 2bromobutane, to be investigated in
+selective photodissociation and enantiomeric discrimination.",1701.07315v1
+2017-04-24,Physics-Based Modeling of TID Induced Global Static Leakage in Different CMOS Circuits,"Compact modeling of inter-device radiation-induced leakage underneath the
+gateless thick STI oxide is presented and validated taking into account CMOS
+technology and hardness parameters, dose-rate and annealing effects, and
+dependence on electric modes under irradiation. It was shown that proposed
+approach can be applied for description of dose dependent static leakage
+currents in complex FPGA circuits.",1704.07265v2
+2018-05-09,Electro-optic polarization tuning of microcavities with a single quantum dot,"We present an oxide aperture microcavity with embedded quantum dots that
+utilizes a three contact design to independently tune the quantum dot
+wavelength and birefringence of the cavity modes. A polarization splitting
+tuning of $\sim$5 GHz is observed. For typical microcavity polarization
+splittings, the method can be used to achieve perfect polarization degeneracy
+that is required for many polarization-based implementations of photonic
+quantum gates. The embedded quantum dot wavelength can be tuned into resonance
+with the cavity, independent of the polarization tuning.",1805.03387v1
+2018-05-18,Origin of magnetoresistance suppression in thin $γ$-MoTe$_2$,"We use both classical magnetotransport and quantum oscillation measurements
+to study the thickness evolution of the extremely large magnetoresistance (XMR)
+material and type-II Weyl semimetal candidate, $\gamma$-MoTe$_2$, protected
+from oxidation. We find that the magnetoresistance is systematically suppressed
+with reduced thickness. This occurs concomitantly with both a decrease in
+carrier mobility and increase in electron-hole imbalance. We model the two
+effects separately and conclude that the XMR effect is more sensitive to the
+former.",1805.07332v1
+2009-12-04,On the mechanism of negative compressibility in layered compounds,"A mechanism of negative compressibility occurring in compressed layered
+compounds in the presence of a pressure transmitting fluid medium is discussed
+within a simple model. It takes into account the excluded volume effects and
+soft fluid-matrix repulsion. It is demonstrated that a non-monotonic behavior
+of the interlayer spacing with the applied pressure results from a competition
+between the applied pressure and the internal one induced by the adsorbed
+fluid. Recent experimental data on the graphite oxide ""structure breathing""
+under compression in the presence of water are analyzed in the light of these
+theoretical results.",0912.0892v1
+2011-11-10,High-Temperature Superconductivity Mechanism for Cuprates,"Egorov and March plotted the product of resistivity and the copper
+spin-lattice relaxation time vs. temperature for yttrium barium copper oxide
+finding a minimum at temperature T greater than the superconducting
+temperature, heralding an electronic phase change which can be interpreted as
+the formation of a ""preformed"" pair. In this context we propose a
+superconducting mechanism based on the notion that the preformed pair is a
+""soft"" boson (a localized, different type of Cooper pair) which dissociates
+above the classical BKT transition temperature, resulting in two circular
+charge density waves. The model suggests explanations for considerable
+experimental work and offers a physical explanation for the basis of the
+Uemura-Homes law.",1111.2560v1
+2011-11-15,Integrated TiO2 resonators for visible photonics,"We demonstrate waveguide-coupled titanium dioxide (TiO2) racetrack resonators
+with loaded quality factors of 2x10^4 for the visible wavelengths. The
+structures were fabricated in sputtered TiO2 thin films on oxidized silicon
+substrates using standard top-down nanofabrication techniques, and passively
+probed in transmission measurements using a tunable red laser. Devices based on
+this material could serve as integrated optical elements as well as passive
+platforms for coupling to visible quantum emitters.",1111.3545v1
+2012-01-17,Multiscale Fractal Descriptors Applied to Nanoscale Images,"This work proposes the application of fractal descriptors to the analysis of
+nanoscale materials under different experimental conditions. We obtain
+descriptors for images from the sample applying a multiscale transform to the
+calculation of fractal dimension of a surface map of such image. Particularly,
+we have used the}Bouligand-Minkowski fractal dimension. We applied these
+descriptors to discriminate between two titanium oxide films prepared under
+different experimental conditions. Results demonstrate the discrimination power
+of proposed descriptors in such kind of application.",1201.3410v1
+2012-01-24,Determining the Location and Cause of Unintentional Quantum Dots in a Nanowire,"We determine the locations of unintentional quantum dots (U-QDs) in a silicon
+nanowire with a precision of a few nanometers by comparing the capacitances to
+multiple gates with a capacitance simulation. Because we observe U-QDs in the
+same location of the wire in multiple devices, their cause is likely to be an
+unintended consequence of the fabrication, not random atomic-scale defects as
+is typically assumed. The locations of the U-QDs appear consistent with
+conduction band modulation from strain from the oxide and the gates. This
+allows us to suggest methods to reduce the frequency of U-QDs.",1201.5144v1
+2012-01-25,Internal loss of superconducting resonators induced by interacting two level systems,"In a number of recent experiments with microwave high quality superconducting
+coplanar waveguide (CPW) resonators an anomalously weak power dependence of the
+quality factor has been observed. We argue that this observation implies that
+the monochromatic radiation does not saturate the Two Level Systems (TLS)
+located at the interface oxide surfaces of the resonator and suggests the
+importance of their interactions. We estimate the microwave loss due to
+interacting TLS and show that the interactions between TLS lead to a drift of
+their energies that result in a much slower, logarithmic dependence of their
+absorption on the radiation power in agreement with the data.",1201.5299v2
+2012-04-04,Intrinsic instability of electronic interfaces with strong Rashba coupling,"We consider a model for the two-dimensional electron gas formed at the
+interface of oxide heterostructures, which includes a Rashba spin-orbit
+coupling proportional to the electric field perpendicular to the interface.
+Based on the standard mechanism of polarity catastrophe, we assume that the
+electric field is proportional to the electron density. Under these simple and
+general assumptions, we show that a phase separation instability occurs for
+realistic values of the spin-orbit coupling and of the band parameters. This
+could provide an intrinsic mechanism for the recently observed inhomogeneous
+phases at the LaAlO_3/SrTiO_3 or LaTiO_3/SrTiO_3 interfaces.",1204.0962v3
+2012-04-09,Reversible switching of room temperature ferromagnetism in CeO2-Co nanoparticles,"We investigated the reversible ferromagnetic (FM) behavior of pure and Co
+doped CeO2 nanopowders. The as-sintered samples displayed an increasing
+paramagnetic contribution upon Co doping. Room temperature FM is obtained
+simply by performing thermal treatments in vacuum at temperatures as low as
+500^{\circ}C and it can be switched off by performing thermal treatments in
+oxidizing conditions. The FM contribution is enhanced as we increase the time
+of the thermal treatment in vacuum. Those systematic experiments establish a
+direct relation between ferromagnetism and oxygen vacancies and open a path for
+developing materials with tailored properties.",1204.1959v1
+2012-04-10,Losses in superconducting Niobium Films caused by Interface Tunnel Exchange,"Identifying the loss mechanisms of niobium film cavities enables an accurate
+determination of applications for future accelerator projects and points to
+research topics required to mitigate their limitations. Measurements on samples
+show that the electric field is a dominant loss mechanism for niobium films,
+acting through interface tunneling between localized states in surface oxides
+and delocalized states in the superconducting niobium.",1204.2166v3
+2012-04-11,Laser written junctionless dual in-plane-gate thin-film transistors with AND Logic function,"A simple laser scribing process has been developed to fabricate low-voltage
+junctionless in-plane-gate thin-film transistors (TFTs) arrays without any mask
+and photolithography. Such junctionless TFTs feature that the channel and the
+source/drain electrodes are of the same indium-tin-oxide films without any
+intentional source/drain junction deposition process. Effective field-effect
+modulation of the drain current has been realized on such in-plane-gate device
+with a field-effect mobility of ~12.6cm2/Vs. At last, AND gate logic function
+was demonstrated on dual in-plane-gate device.",1204.2312v1
+2012-04-16,Ab initio investigation of competing instabilities in ferroelectric perovskite PbTiO3,"We have developed first-principles models, based on a general parametrization
+of the full potential-energy surface, to investigate the lattice-dynamical
+properties of perovskite oxides. We discuss the application of our method to
+prototypic ferroelectric PbTiO3, showing that its properties are drastically
+affected by a competition between structural instabilities. Indeed, we confirm
+previous indications that the destructive interaction between the ferroelectric
+and antiferrodistortive (involving rotations of the O6 octahedra) soft modes
+shifts PbTiO3's Curie temperature by hundreds of degrees. Our theory provides
+unique insight into this gigantic effect and its dynamical character.",1204.3394v1
+2012-04-20,High carrier mobility in transparent Ba1-xLaxSnO3 crystals with a wide band gap,"We discovered that perovskite (Ba,La)SnO3 can have excellent carrier mobility
+even though its band gap is large. The Hall mobility of Ba0.98La0.02SnO3
+crystals with the n-type carrier concentration of \sim 8-10\times10 19 cm-3 is
+found to be \sim 103 cm2 V-1s-1 at room temperature, and the precise
+measurement of the band gap \Delta of a BaSnO3 crystal shows \Delta=4.05 eV,
+which is significantly larger than those of other transparent conductive
+oxides. The high mobility with a wide band gap indicates that (Ba,La)SnO3 is a
+promising candidate for transparent conductor applications and also epitaxial
+all-perovskite multilayer devices.",1204.4657v1
+2012-04-23,Ferroelectricity induced by cooperative orbital ordering and Peierls instability,"A general mechanism by which orbital ordering, coupled to Peierls-like
+lattice distortions, can induce an electronic switchable polarization is
+discussed within a model Hamiltonian approach in the context of the modern
+theory of polarization. By using a Berry-phase approach, a clear picture
+emerges in terms of Wannier-function centers and orbital occupancies. The
+proposed mechanism may apply to oxide spinels whose electronic structure has
+effective one-dimensional character, such as CdV$_2$O$_4$, recently proposed to
+display multiferroic behaviour.",1204.5106v1
+2012-04-24,A Silicon Optical Transistor,"A fundamental road block for all-optical information processing is the
+difficulty in realizing a silicon optical transistor with the ability to
+provide optical gain, input output isolation and buffer action. In this work,
+we demonstrate an all-optical transistor using optical nonlinearity in
+microrings. By using weak light to control strong light, we observed an On/Off
+ratio up to 20 dB. It can compensate losses in other optical devices and
+provide fan-out capability. The device is ultra compact and is compatible with
+current complementary metal-oxide-semiconductor (CMOS) processing.",1204.5515v1
+2012-04-27,On the effect of oxygen partial pressure on the chromium distribution coefficient in melt-grown ruby crystals,"Small ruby crystals were grown by the Czochralski technique in different
+atmospheres and their actual chromium content was analysed by a wet chemical
+method. The chromium distribution coefficient k was found to be strongly
+dependent on oxygen partial pressure p(O2). It ranges from k=0.3 in a reducing
+atmosphere to k=1.2 in a slightly oxidizing atmosphere and to a good
+approximation k depends linearly on log(p(O2)). The experimental data are
+discussed on the basis of thermodynamic equilibrium calculations.",1204.6225v1
+2013-09-04,Unexpected colloid-like supernatant from liquid-phase ball-milling graphite using miscible solutions as solvents: a failure analysis,"Ball-milling graphite was conducted in miscible solutions with the purpose to
+exfoliate graphene. Colloid-like stable supernatants were unexpectedly
+obtained. Followed were the characterizations with Scanning electronic
+microscopy, Thermogravimetric analysis, X-ray diffraction and Elemental
+dispersive X-ray mapping to recognize them. As a result, strongly against the
+initial judgments, the components of colloid were mainly impurities of mixture
+of zirconia, silicate and yttrium oxide, other than nano-graphite.",1309.1056v2
+2013-09-05,Persistent photoconductivity in oxygen deficient YBCO/LCMO superlattices grown by PLD,"We report a large persistent photoconductivity (PPC) in oxygen reduced PLD
+grown YBa2Cu3O7-{\delta}/La2/3Ca1/3MnO3-y (YBCO/LCMO) superlattices scaling
+with the oxygen deficiency and being similar to that observed in single layer
+YBa2Cu3O7-{\delta} films. These results contradict previous observations where
+in sputtered bilayer samples only a transient photoconductivity (TPC) was
+found. We argue that the PPC effect in superlattices is caused by the PPC
+effect due to the YBa2Cu3O7-x layers with limited charge transfer to
+La2/3Ca1/3MnO3-y. The discrepancy arises from the different permeability of
+charges across the interface and shed light on the sensitivity of oxide
+interface properties on details of their preparation.",1309.1295v1
+2013-09-07,TCO Nanostructures as building blocks for nanophotonic devices in the infrared,"Transparent conducting oxides (TCOs), in general, are degenerated
+semiconductors with large electronic band-gap. They have been widely used for
+display screens, optoelectronic, photonic, and photovoltaic devices due to
+their unique dual transparent and conductive properties. In this study, we
+report in detail a technique that we developed to fabricate single crystal TCO
+nanorod arrays with controlled conductivity, height, and lattice spacing in a
+simple one-zone tube furnace system. We demonstrate how novel
+photonic/plasmonic properties can be obtained by selecting unique combinations
+of these basic parameters of the nano-rod arrays.",1309.1819v1
+2013-09-16,Nucleation and growth of metal whiskers,"The existence of metal whiskers is attributed to the energy gain due to
+electrostatic polarization of needle shaped metal filaments in the electric
+field induced by surface imperfections: contaminations, oxide states, etc. A
+proposed theory provides closed form expressions for the whisker nucleation and
+growth rates, explains the range of whisker parameters and effects of external
+biasing. It predicts a well controlled whisker growth on any metal surface via
+generating surface plasmon polariton excitations.",1309.3822v3
+2013-09-24,Electrophysical properties of PMN-PT-PS-PFN:Li ceramics,"We present the technology of obtaining and the electrophysical properties of
+a multicomponent material 0.61PMN-0.20PT-0.09PS-0.1PFN:Li (PMN-PT-PS-PFN:Li).
+The addition of PFN into PMN-PT decreases the temperature of final sintering
+which is very important during technological process (addition of Li decreases
+electric conductivity of PFN). Addition of PS i.e., PbSnO_3 (which is unstable
+in ceramic form) permits to shift the temperature of the maximum of dielectric
+permittivity. One-step method of obtaining ceramic samples from oxides and
+carbonates has been used. XRD, microstructure, scanning calorimetry
+measurements and the main dielectric, ferroelectric and electromechanical
+properties have been investigated for the obtained samples.",1309.6093v1
+2014-04-19,Negative Capacitance Tunnel Field Effect Transistor: A Novel Device with Low Subthreshold Swing and High ON Current,"In this paper we propose a modified structure of TFET incorporating
+ferroelectric oxide as the complementary gate dielectric operating in negative
+capacitance zone, called the Negative Capacitance Tunnel FET (NCTFET). The
+proposed device effectively combines two different mechanisms of lowering the
+sub threshold swing (SS) for a transistor garnering a further lowered one
+compared to conventional TFET. A simple yet accurate analytical tunnel current
+model for the proposed device is also presented here. The developed analytical
+model demonstrates high ON current at low $V_{GS}$ and exhibits lower SS.",1405.5169v1
+2014-05-25,Complementary memristive device based on a thin film of MoS2 monolayers,"In this manuscript we demonstrate experimentally that a thin film of MoS2
+monolayers formed by drop-casting on a gold interdigitated electrode on Si/SiO2
+behaves like a complementary memristive device, which is a key device of future
+crossbar memories. The hysteretic behavior of this device is modulated by light
+in a spectral range expanding from UV up to IR. In contrast to previous
+complementary memristive devices based on complicated oxides heterostructures,
+this device has a simple fabrication procedure and can be controlled by light,
+in addition to electrical signals.",1405.6406v1
+2014-06-02,New Electrochemical Characterization Methods for Nanocomposite Supercapacitor Electrodes,"Supercapacitor electrodes fabricated from a nanocomposite consisting of
+multiwall carbon nanotubes and titanium oxide nanoparticles were characterized
+electrochemically. Conventional electrochemical characterizations cyclic
+voltammetry and galvanostatic charge-discharge in a lithium-based electrolyte
+gave a specific capacitance of 345 F/g at a current density of 0.1 A/g. New
+electrochemical characterization techniques that allow one to obtain the peak
+capacitance associated with intercalation and to distinguish between
+electrostatic and faradaic charge storage are described and applied to the
+electrode measurements. Finally, the maximum energy density obtained was 31
+Wh/kg.",1406.0470v3
+2016-05-01,Further results on degree based topological indices of certain chemical networks,"There are various topological indices such as degree based topological
+indices, distance based topological indices and counting related topological
+indices etc. These topological indices correlate certain physicochemical
+properties such as boiling point, stability of chemical compounds. In this
+paper, we compute the sum-connectivity index and multiplicative Zagreb indices
+for certain networks of chemical importance like silicate networks, hexagonal
+networks, oxide networks, and honeycomb networks. Moreover, a comparative study
+using computer-based graphs has been made to clarify their nature for these
+families of networks.",1605.00253v2
+2016-05-02,First Principles Prediction of Amorphous Phases Using Evolutionary Algorithms,"We discuss the efficacy of evolutionary method for the purpose of structural
+analysis of amorphous solids. At present ab initio molecular dynamics (MD)
+based melt-quench technique is used and this deterministic approach has proven
+to be successful to study amorphous materials. We show that a stochastic
+approach motivated by Darwinian evolution can also be used to simulate
+amorphous structures. Applying this method, in conjunction with density
+functional theory (DFT) based electronic, ionic and cell relaxation, we
+re-investigate two well known amorphous semiconductors, namely silicon and
+indium gallium zinc oxide (IGZO). We find that characteristic structural
+parameters like average bond length and bond angle are within $\sim$ 2% to
+those reported by ab initio MD calculations and experimental studies.",1605.00516v1
+2016-05-10,Analysis of 3D-printed metal for rapid-prototyped reflective terahertz optics,"We explore the potential of 3D metal printing to realize complex conductive
+terahertz devices. Factors impacting performance such as printing resolution,
+surface roughness, oxidation, and material loss are investigated via
+analytical, numerical, and experimental approaches. The high degree of control
+offered by a 3D-printed topology is exploited to realize a zone plate operating
+at 530 GHz. Reflection efficiency at this frequency is found to be over 90%.
+The high-performance of this preliminary device suggest that 3D metal printing
+can play a strong role in guided-wave and general beam control devices in the
+terahertz range.",1605.03246v1
+2016-08-05,Density functional theory calculations of the stress of oxidised (110) silicon surfaces,"The measurement of the lattice-parameter of silicon by x-ray interferometry
+assumes the use of strain-free crystals. This might not be the case because
+surface relaxation, reconstruction, and oxidation cause strains without the
+application of any external force. In a previous work, this intrinsic strain
+was estimated by a finite element analysis, where the surface stress was
+modeled by an elastic membrane having a 1 N/m tensile strength. The present
+paper quantities the surface stress by a density functional theory calculation.
+We found a value exceeding the nominal value used, which potentially affects
+the measurement accuracy.",1608.01885v1
+2016-08-29,Full elasticity tensor from thermal diffuse scattering,"We present a method for the precise determination of the full elasticity
+tensor from a single crystal diffraction experiment using monochromatic X-rays.
+For the two benchmark systems calcite and magnesium oxide we show that the
+measurement of thermal diffuse scattering in the proximity of Bragg reflections
+provides accurate values of the complete set of elastic constants. This
+approach allows for a reliable and model free determination of the elastic
+properties and can be performed together with crystal structure investigation
+in the same experiment.",1608.08061v1
+2016-12-02,"A preliminary DFT study of the adsorption and dissociation of $CH_{4}$,$SO_{2}$ and $O_{2}$ reactions on $Cr_{2}O_{3}(0001)$","In the present work, we study the structures and molecular geometries of
+$CH_{4}$, $SO_{2}$ and $O_{2}$ adsorbed on $Cr_{2}O_{3}(0001)$. Using
+computational calculations based on the density functional theory (DFT), we
+analyze the most suitable sites to carry out the adsorption of each of the
+molecules mentioned, and the influence of each species on the adsorption and
+dissociation of the others. The results allow us to understand the activation
+of the $Cr_{2}O_{3}(0001)$ surface, which leads to the presence of $SO_{2}$
+during the oxidation of $CH_{4}$, as was experimentally verified.",1612.00672v1
+2016-12-22,Coulomb Correlations in 4d and 5d Oxides from First Principles - or How Spin-Orbit Materials choose their Effective Orbital Degeneracies,"The interplay of spin-orbit interactions and Coulomb correlations has become
+a hot topic in condensed matter theory. Here, we review recent advances in
+dynamical mean-field theory-based electronic structure calculations for
+iridates and rhodates. We stress the notion of the effective degeneracy of the
+compounds, which introduces an additional axis into the conventional picture of
+a phase diagram based on filling and on the ratio of interactions to bandwidth.",1612.07546v1
+2017-06-01,FeSe(en)0.3 - Separated FeSe layers with stripe-type crystal structure by intercalation of neutral spacer molecules,"Solvothermal intercalation of ethylenediamine molecules into FeSe separates
+the layers by 1078 pm and creates a different stacking. FeSe(en)0.3 is not
+superconducting although each layer exhibits the stripe-type crystal structure
+and the Fermi surface topology of superconducting FeSe. FeSe(en)0.3 requires
+electron-doping for high-Tc similar to monolayers of FeSe@SrTiO3, whose much
+higher Tc may arise from the proximity of the oxide surface.",1706.00314v1
+2017-06-04,Electric field induced phase transition and electrocaloric effect in PMN-PT,"Ferroelectric perovskite oxides possess a large electrocaloric (EC) effect,
+but usually at high temperatures near the ferroelectric/paraelectric phase
+transition temperature, which limits their potential application as
+next-generation solid-state cooling devices. We use classical molecular
+dynamics to study the electric field induced phase transitions and EC effect in
+PMN-PT (PbMg1/3Nb2/3O3-PbTiO3). We find that the maximum EC strength of PMN-PT
+occurs within the morphotropic phase boundary (MPB) region at 300 K. The large
+adiabatic temperature change is caused by easy rotation of polarization within
+the MPB region.",1706.01034v2
+2017-06-06,Autoignition of Butanol Isomers at Low to Intermediate Temperature and Elevated Pressure,"Autoignition delay experiments for the isomers of butanol, including n-,
+sec-, tert-, and iso-butanol, have been performed using a heated rapid
+compression machine. For a compressed pressure of 15 bar, the compressed
+temperatures have been varied in the range of 725-855 K for all the
+stoichiometric fuel/oxidizer mixtures. Over the conditions investigated in this
+study, the ignition delay decreases monotonically as temperature increases and
+exhibits single-stage characteristics. Experimental ignition delays are also
+compared to simulations computed using three kinetic mechanisms available in
+the literature. Reasonable agreement is found for three isomers (tert-, iso-,
+and n-butanol).",1706.01837v1
+2017-06-07,What can one learn about material structure given a single first-principles calculation?,"We extract a variable $X$ from electron orbitals $\Psi_{n\bf{k}}$ and
+energies $E_{n\bf{k}}$ in the parent high-symmetry structure of a wide range of
+complex oxides: perovskites, rutiles, pyrochlores, and cristobalites. Even
+though calculation was done only in the parent structure, with no distortions,
+we show that $X$ dictates material's true ground state structure. We propose
+using Wannier functions to extract concealed variables such as $X$ both for
+material structure prediction and for high-throughput approaches.",1706.02012v2
+2017-06-15,Studies on thermal degradation behavior of nano silica loaded cotton and polyester fabrics,"In this work cotton and polyester fabric were coated with silica nano
+particles using pad-dry-cure method. The prepared composite fabrics were
+analyzed in terms of change in their thermal degradation properties. The
+oxidative degradation characteristic of control and treated samples were
+studied using Thermo Gravimetric technique. The mass loss profile of untreated
+fabric compared with treated fabric. The results indicate that the thermal
+degradation rate was lower in treated sample as compare to control fabrics.",1706.04777v1
+2017-06-27,Self-Assembled Monolayer Piezoelectrics: Electric-Field Driven Conformational Changes,"We demonstrate that an applied electric field causes piezoelectric distortion
+across single molecular monolayers of oligopeptides. We deposited
+self-assembled monolayers ~1.5 nm high onto smooth gold surfaces. These
+monolayers exhibit strong piezoelectric response that varies linearly with
+applied bias (1-3V), measured using piezoresponse force microscopy (PFM). The
+response is markedly greater than control experiments with rigid alkanethiols
+and correlates with surface spectroscopy and theoretical predictions of
+conformational change from applied electric fields. Unlike existing
+piezoelectric oxides, our peptide monolayers are intrinsically flexible, easily
+fabricated, aligned and patterned without poling.",1706.08993v2
+2017-10-05,Electronic Transport Properties of Carrier Controlled SnSe Single Crystals,"We found that the electronic transport property of SnSe single crystals was
+sensitive to oxygen content. Semiconducting SnSe single crystals were obtained
+by using Sn of grain form as a starting material while powder Sn resulted in
+metallic SnSe. X-ray photoelectron spectroscopy analysis revealed that the
+surfaces of raw Sn were oxidized, where the volume fraction was relatively low
+in grain Sn. This demonstrates that contamination of oxygen causes metallic
+behavior in grown SnSe single crystals.",1710.01863v1
+2017-12-28,Theoretical calculation of transport properties of oxide material using narrow band model,"We report about the results of theoretical calculations of temperature
+dependence of resistivity ($\rho$) and Seebeck coefficient ($S$) for
+thermoelectric (TE) and superconductivity (SC) phases by arithmetic equations
+based on narrow band model with oxygen deficient structure, as the functions of
+band-filling degree ($F$), and band width ratio of electron and spin states
+($W$\sigma/$W$D). The phase diagrams of TE and SC states, and boundary were
+imaged to the properties of $\rho$ and $S$ as a function of $F$ and
+$W$\sigma/$W$D.",1712.09840v1
+2018-01-03,Reduction of Nitrogen Oxides (NOx) by Superalkalis,"NOx are major air pollutants, having negative impact on environment and
+consequently, human health. We propose here the single-electron reduction of
+NOx (x = 1, 2) using superalkalis. We study the interaction of NOx with FLi2,
+OLi3 and NLi4 superalkalis using density functional calculations, which lead to
+stable superalkali-NOx ionic complexes with negatively charged NOx. This
+clearly reveals that the NOx can successfully be reduced to NOx- anion due to
+electron transfer from superalkalis. It has been also noticed that the size of
+superalkalis plays a crucial in the single-electron reduction of NOx.",1801.00913v1
+2018-09-11,Al-Cu-Fe quasicrystals as anode of lithium ion battery,"In this paper, Al-Cu-Fe quasicrystal alloy was used as anode material of
+lithium-ion batteries. The first specific discharge capacity of quasicrystal
+was 204mAh/g. Cyclic voltammetry showed that oxidation peak of Al-Cu-Fe
+quasicrystal was at about 1.4V. The reduction peak was at 0.3V. Al-Cu-Fe
+quasicrystal have higher Li-ion diffusion impedance and Warburg in the first
+cycle. X-ray diffraction analysis demonstrate that Li atom enter into
+quasicrystal structure can not fully leave quasicrytal during first
+charge/discharge cycle which induce the irreversible capacity.",1809.03667v1
+2018-10-18,Strengthening of copper by carbon nanotubes,"The influence of a modifier based on multi walled carbon nanotubes (MWCNT) is
+investigated using C11000 copper alloy. The influence of the modifier addition
+into the melt was investigated using tensile test, hardness measurements, X-ray
+diffraction method and microstructural investigations. It was evaluated that
+the yield and tensile strengths of the metal increased due to the
+microstructural changes in the formed metal after addition of 0.01wt.% of the
+MWCNTs. It was also evaluated that the addition of mentioned amount of MWCNT
+into alloy has no influence to the phase composition of the formed metal.",1810.08019v1
+2018-10-19,Lévy flights confinement in a parabolic potential and fractional quantum oscillator,"We study L\'evy flights confined in a parabolic potential. This has to do
+with a fractional generalization of ordinary quantum-mechanical oscillator
+problem. To solve the spectral problem for the fractional quantum oscillator,
+we pass to the momentum space, where we apply the variational method. This
+permits to obtain approximate analytical expressions for eigenvalues and
+eigenfunctions with very good accuracy. Latter fact has been checked by
+numerical solution of the problem. We point to the realistic physical systems
+ranging from multiferroics and oxide heterostructures to quantum chaotic
+excitons, where obtained results can be used.",1810.08422v1
+2018-10-21,Inversion of oxygen potential transitions at grain boundaries of SOFC/SOEC electrolytes,"Solid oxide fuel/electrolyzer cell (SOFC/SOEC) converts energy between
+chemical and electrical forms inversely. Yet electrolyte degradation takes
+place much more severe for SOEC than SOFC during long-term operations. By
+solving transport equations, we found very large oxygen potential gradients and
+sharp oxygen potential transitions at grain boundaries of polycrystalline
+SOFC/SOEC electrolyte. Surprisingly, an inversion of oxygen potential
+transitions was identified, suggesting a fundamentally different transport
+mechanism for minor electronic charge carriers. Such findings could be critical
+to understand and eliminate SOFC/SOEC degradations in practical applications.",1810.09016v1
+2019-06-09,Experimental Investigation of Crack Jumps during Initiation and Growth in IN718,"The following study investigates the statistical nature of crack jumps during
+fatigue of Inconel 718. In-situ measurement in atmospheric air of the crack
+length at several loading and temperature conditions was conducted using a
+direct current potential drop (DCPD) method. Both annealed and heat-treated
+Inconel 718 samples were investigated. For a single sample, the normalized
+change of crack length was confirmed to not be a random process. This finding
+is significant in highlighting the time history features, which could be used
+in training machine learning models for the fundamental understanding of
+oxidation and the prediction of crack initiation and growth.",1906.03681v3
+2019-06-11,Defect-Moderated Oxidative Etching of MoS2,"We report a simple technique for the selective etching of bilayer and
+monolayer MoS$_2$. In this work, chosen regions of MoS$_2$ were activated for
+oxygen adsorption and reaction by the application of low doses of He$^+$ at 30
+keV in a gas ion microscope. Raman spectroscopy, optical microscopy and
+scanning electron microscopy were used to characterize both the etched features
+and the remaining material. It has been found that by using a pre-treatment to
+introduce defects, MoS$_2$ can be etched very efficiently and with high region
+specificity by heating in air.",1906.04850v1
+2019-06-07,274-GHz CMOS Signal Generator with an On-Chip Patch Antenna in a QFN Package,"A 274-GHz signal generator with an on-chip antenna in a quad-flat no-leads
+(QFN) package is demonstrated. The circuit is fabricated in a 65-nm
+Complementary Metal Oxide Semiconductor (CMOS) process. The effective isotropic
+radiated power (EIRP) measured from the packaged signal generator is -12.8-dBm
+at 274GHz with DC power consumption of 26.3mW. The packaging material can help
+improve the antenna performance, and integrated circuits with on-chip antennas
+operating at ~300GHz can be packaged using low-cost techniques.",1906.05117v1
+2019-06-25,Impact of Extrinsic Interface Traps and Doping Atoms on Conductivity of Graphene Field Effect Devices,"Near-interfacial oxide traps and chemical impurities on the graphene surface
+or at the graphene-dielectric interface can be a source of intentional or
+unintentional doping of graphene sheet. The efficiency of such chemical doping
+can vary in a wide range depending on parameters of graphene field effect
+devices. Mechanisms of such sensitivity of doping efficiency to the device
+characteristics need to be understood. The objective of this paper is to
+theoretically derive the analytical relations, adapted to the explicit
+calculation of graphene chemical doping.",1906.10476v1
+2019-07-05,Enhancing electrical conductivity of room temperature deposited Sn-doped In$_2$O$_3$ thin films by hematite seed layers,"Hematite Fe$_2$O$_3$ seed layers are shown to constitute a pathway to prepare
+highly conductive transparent tin-doped indium oxide (ITO) thin films by room
+temperature magnetron sputtering. Conductivities of up to $\sigma = 3300\,{\rm
+S/cm}$ are observed. The improved conductivity is not restricted to the
+interface but related to an enhanced crystallization of the films, which
+proceeds in the rhombohedral phase.",1907.02867v1
+2019-07-10,In Praise and in Search of Highly-Polarizable Semiconductors,"The dielectric response of materials underpins electronics and photonics.
+Established semiconductor materials have a narrow range of dielectric
+susceptibility, with low-frequency values on the order of 10. Strong and
+variable dielectric response in wide-band gap materials is associated with
+complex crystal structures and heavier elements. Based on underlying chemical
+trends, we hypothesize that chalcogenides in crystal structures common to
+complex oxides may feature many highly-polarizable semiconductors. Research on
+these materials is motivated by fundamental inquiry into electrons and phonons
+in solids, and by potential applications in photonics, high-frequency
+communications, and photovoltaics.",1907.04600v1
+2019-07-13,High-performance super-capacity using activated glassy carbon foam,"An urgent demand for new sustainable and efficient energy conversion and
+storage devices required the development of novel electrode materials with
+increased specific capacitance. However, low mass loading, poor scalability,
+and low working voltage always limited further practical application of most
+reported high-performance supercapacitors electrode materials. In this work, we
+demonstrated the preparation of activated glassy carbon foam as
+high-performance electrode via oxidizing commercial glassy carbon foam in HNO3
+solution.",1907.06031v2
+2019-07-24,On Calibration of a Nominal Structure-Property Relationship Model for Chiral Sculptured Thin Films by Axial Transmittance Measurements,"A chiral sculptured thin film is fabricated from patinal titanium oxide using
+the serial bideposition technique. Axial transmittance spectrums are measured
+over a spectral region encompassing the Bragg regime for axial excitation. The
+same spectrums are calculated using a nominal structure-property relationship
+model and the parameter space of the model is explored for best fits of the
+calculated and measured transmittances. Ambiguity arising on calibrating the
+model against axial transmittance measurements is shown to be resolvable using
+non--axial transmittance measurements.",1907.10740v1
+2019-10-02,Transition to bound states for bacteria swimming near surfaces,"It is well known that flagellated bacteria swim in circles near surfaces.
+However, recent experiments have shown that a sulfide-oxidizing bacterium named
+Thiovulum majus can transition from swimming in circles to a surface bound
+state where it stops swimming while remaining free to move laterally along the
+surface. In this bound state, the cell rotates perpendicular to the surface
+with its flagella pointing away from it. Using numerical simulations and
+theoretical analysis, we demonstrate the existence of a fluid-structure
+interaction instability that causes cells with relatively short flagella to
+become surface bound.",1910.01502v1
+2020-01-15,Intense Anti-Stokes Emission of Erbium Ions in Gallium Lanthanum Sulphide-Oxide Glass in Visible Spectral Range,"Photoluminescence spectra have been investigated in erbium doped GaLaS(O)
+glasses. The samples demonstrate intense green emission bands centered at
+around 525 and 550 nm due to up-conversion processes in erbium ions. The
+theoretical description of up-conversion intensity as a function of excitation
+intensity has been offered. It is based on a solution of a system of rate
+equations taking into account three up-conversion transitions.",2001.05464v1
+2020-01-28,A C/V$_2$O$_5$ core-sheath nanofibrous cathode with mixed-ion intercalation for aluminium-ion batteries,"A new nanofibrous material, consisting of a conductive carbon core and an
+external layer made of vanadium oxide, has been studied as a cathode for
+aluminium-ion batteries. The material enables a mixed-ion intercalation
+mechanism, resulting in the alternating insertion of $\text{Al}^{3+}$ and
+$\text{AlCl}_4^-$ in the $\text{V}_2\text{O}_5$ and carbon layers,
+respectively. This is a highly desirable feature for cathode materials which
+may increase the energy density of future batteries by optimising the
+utilisation of the electrolyte.",2001.10153v2
+2020-04-23,X-ray phase contrast topography to measure the surface stress and bulk strain in a silicon crystal,"The measurement of the Si lattice parameter by x-ray interferometry assumes
+the use of strain-free crystals, which might not be true because of intrinsic
+stresses due to surface relaxation, reconstruction, and oxidation. We used
+x-ray phase-contrast topography to investigate the strain sensitivity to the
+finishing, annealing, and coating of the interferometer crystals.We assessed
+the topography capabilities by measuring the lattice strain due to films of
+copper deposited on the interferometer mirror-crystal. A byproduct has been the
+measurement of the surface stresses after complete relaxation of the coatings.",2004.11275v2
+2020-12-18,A CMOS Compatible Aluminum Scandium Nitride-based Ferroelectric Tunnel Junction Memristor,"We report a complementary metal oxide semiconductor (CMOS) technology
+compatible ferroelectric tunnel junction memristor grown directly on top of a
+Silicon substrate using a scandium doped aluminum nitride as the ferroelectric
+layer.",2012.10019v2
+2012-05-01,Coexistence of two- and three-dimensional Shubnikov-de Haas oscillations in Ar^+ -irradiated KTaO_3,"We report the electron doping in the surface vicinity of KTaO_3 by inducing
+oxygen-vacancies via Ar^+ -irradiation. The doped electrons have high mobility
+(> 10^4 cm^2/Vs) at low temperatures, and exhibit Shubnikov-de Haas
+oscillations with both two- and three-dimensional components. A disparity of
+the extracted in-plane effective mass, compared to the bulk values, suggests
+mixing of the orbital characters. Our observations demonstrate that Ar^+
+-irradiation serves as a flexible tool to study low dimensional quantum
+transport in 5d semiconducting oxides.",1205.0197v1
+2012-05-07,Suppression of Multilayer Graphene Patches during CVD Graphene growth on Copper,"By limiting the carbon segregation at the copper surface defects, a pulsed
+chemical vapor deposition method for single layer graphene growth is shown to
+inhibit the formation of few-layer regions, leading to a fully single-layered
+graphene homogeneous at the centimeter scale. Graphene field-effect devices
+obtained after transfer of pulsed grown graphene on oxidized silicon exhibit
+mobilities above 5000 cm^2.V^-1.s^-1.",1205.1337v1
+2012-05-30,"Multiple Superconducting Gaps, Anisotropic Spin Fluctuations and Spin-Orbit Coupling in Iron-Pnictides","This article reviews the NMR and NQR studies on iron-based high-temperature
+superconductors by the IOP/Okayama group. It was found that the electron pairs
+in the superconducting state are in the spin-singlet state with multiple
+fully-opened energy gaps. The antiferromagnetic spin fluctuations in the normal
+state are found to be closely correlated with the superconductivity. Also the
+antiferromagnetic spin fluctuations are anisotropic in the spin space, which is
+different from the case in copper oxide superconductors. This anisotropy
+originates from the spin-orbit coupling and is an important reflection of the
+multiple-bands nature of this new class of superconductors.",1205.6589v1
+2017-09-04,Interaction of Rydberg Excitons in Cuprous Oxide with Phonons and Photons: Optical Linewidth and Polariton Effect,"We demonstrate that the optical linewidth of Rydberg excitons in Cu2O can be
+completely explained by scattering with acoustical and optical phonons, whereby
+the dominant contributions stems from the non-polar optical modes. The
+consequences for the observation of polariton effects are discussed. We find
+that an anti-crossing of photon and exciton dispersions exists only for states
+with main quantum numbers n>28, so polariton effects do not play any role in
+the experiments reported up to now.",1709.00895v1
+2017-09-25,Light-induced switching in pDTE - FICO 1D photonic structures,"We propose the design of 1D photonic crystals and microcavities in which
+fluorine-indium codoped cadmium oxide (FICO) nanocrystal based layers and
+layers of diarylethene-based polyester (pDTE) are alternated or embedded in a
+microcavity. The irradiation with UV light results in two different behaviours:
+i) it dopes the FICO nanocrystals inducing a blue shift of their plasmonic
+resonances; ii) it changes the real part of the refractive index of the
+photochromic pDTE polymer. These two behaviours are combined in the proposed
+photonic structures and can be useful for switchable filters and cavities for
+light emission.",1709.08741v2
+2017-09-26,Photoferroelectric oxides,"Giant photovoltaic effect due to bulk photovoltaic effect observed in
+multiferroic BiFeO3 thin films has triggered a renewed interest on
+photoferroelectric materials for photovoltaic applications. Tremendous advance
+has been done to improve power conversion efficiency (up to up to 8.1%) in
+photoferroelectrics via absorption increase using narrow bandgap
+ferroelectrics. Other strategies, as it is the more efficient use of
+ferroelectric internal electric field, are ongoing. Moreover, as a by-product,
+several progress have been also achieved on photostriction that is the
+photo-induced deformation phenomenon. Here, we review ongoing and promising
+routes to improve ferroelectrics photoresponse.",1709.09202v1
+2017-11-03,Blowing Polar Skyrmion Bubbles in Oxide Superlattices,"Particle-like topological structures such as skyrmions and vortices have
+garnered ever-increasing interests due to the rich physical insights and
+potential broad applications. Here we discover the reversible switching between
+polar skyrmion bubbles and ordered vortex arrays in ferroelectric superlattices
+under an electric field, reminiscent of the Plateau-Raleigh instability in
+fluid mechanics. Electric field phase diagram is constructed, showing wide
+stability window for the observed polar skyrmions. This study is a
+demonstration for the computational design of ferroelectric topological
+structures and field-induced topological phase transitions.",1711.00995v1
+2017-11-05,Selective Orientation of Chiral Molecules by Laser Fields with Twisted Polarization,"We explore a pure optical method for enantioselective orientation of chiral
+molecules by means of laser fields with twisted polarization. Several field
+implementations are considered, including a pair of delayed cross-polarized
+laser pulses, an optical centrifuge, and polarization shaped pulses. The
+underlying classical orientation mechanism common for all these fields is
+discussed, and its operation is demonstrated for a range of chiral molecules of
+various complexity: hydrogen thioperoxide (${\rm HSOH}$), propylene oxide
+(${\rm CH_{3}CHCH_{2}O}$) and ethyl oxirane (${\rm CH_{3}CH_{2}CHCH_{2}O}$).
+The presented results demonstrate generality, versatility and robustness of
+this optical method for manipulating molecular enantiomers in the gas phase.",1711.01552v1
+2017-11-24,E$_8$ in $\mathcal N=8$ supergravity in four dimensions,"We argue that $\mathcal N=8$ supergravity in four dimensions exhibits an
+exceptional $E_{8(8)}$ symmetry, enhanced from the known $E_{7(7)}$ invariance.
+Our procedure to demonstrate this involves dimensional reduction of the
+$\mathcal N=8$ theory to $d=3$, a field redefinition to render the $E_{8(8)}$
+invariance manifest, followed by dimensional oxidation back to $d=4$.",1711.09110v1
+2018-03-21,Large anomalous Nernst coefficient in an oxide Skyrmion crystal Chern insulator,"A sizable transverse thermoelectric coefficient N , large to the extent that
+it potentially serves applications, is predicted to arise, by means of
+first-principles calculations, in a Skyrmion crystal assumed on EuO monolayer
+where carrier electrons are introduced upon a quantum anomalous Hall insulating
+phase of Chern number C = 2. This encourages future experiments to pursue such
+an effect.",1803.08148v2
+2018-03-28,Complementary metal-oxide semiconductor compatible source of single photons at near-visible wavelengths,"We demonstrate on chip generation of correlated pairs of photons in the
+near-visible spectrum using a CMOS compatible PECVD Silicon Nitride photonic
+device. Photons are generated via spontaneous four wave mixing enhanced by a
+ring resonator with high quality Q-factor of 320,000 resulting in a generation
+rate of 950,000 $\frac{pairs}{mW}$. The high brightness of this source offers
+the opportunity to expand photonic quantum technologies over a broad wavelength
+range and provides a path to develop fully integrated quantum chips working at
+room temperature.",1803.10484v1
+2018-06-27,Ultrananocrystalline Diamond Film: Tribological Studies Against Metal and Ceramic Balls,"In this present work, friction and wear behavior of UNCD thin film has been
+studied against three different sliding counterbodies i.e. Al2O3, SiC and steel
+balls. UNCD/steel sliding pair showed high friction coefficient in the
+beginning of the sliding process which decreased to the lower value after
+longer sliding passes. This behavior might be explained by oxidation mechanism.
+However, high friction value was observed in the case of UNCD/SiC and this was
+attributed to strong adhesive force acting across the sliding interfaces.
+Stable and low friction value was measured in UNCD/Al2O3 sliding combination.
+This was governed by chemically inert interfaces and graphite tribolayer
+formation.",1806.10302v1
+2018-07-16,Interactions between Rydberg excitons in Cu$_2$O,"Highly-excited states of excitons in cuprous oxide have recently been
+observed at a record quantum number of up to $n=25$. Here, we evaluate the
+long-range interactions between pairs of Rydberg excitons in Cu$_2$O, which are
+due to direct Coulomb forces rather than short-range collisions typically
+considered for ground state excitons. A full numerical analysis is supplemented
+by the van der Waals asymptotics at large exciton separations, including the
+angular dependence of the potential surfaces.",1807.05896v1
+2018-07-20,Atmosphere Pressure Chemical Vapor Deposition of Graphene,"Recently, graphene is of highly interest owing to its outstanding
+conductivity, mechanical strength, thermal stability, etc. Among various
+graphene synthesis methods, atmosphere pressure chemical vapor deposition
+(APCVD) is one of the best synthesis one due to very low diffusitivity
+coefficient and a critical step for graphene-based device fabrication.
+High-temperature APCVD processes for thin film productions are being recognized
+in many diversity technologies such as solid-state electronic devices, in
+particular, high quality epitaxial semiconductor films for silicon bipolar and
+metal oxide semiconductor (MOS) transistors. Graphene-based devices exhibit
+high potential for applications in flexible electronics, optoelectronics, and
+energy harvesting. In this chapter, recent advances of APCVD-based graphene
+synthesis and their related applications will be addressed.",1807.07774v1
+2018-08-05,Role of Doping Ratio on The Sensing Properties of ZnO:SnO2 Thin Films,"Thin films of ZnO:SnO2 were deposited on different substrates like glass and
+c-Si using spray pyrolysis method .The structures and morphology of the
+prepared samples films were cheeked using X-ray diffraction and atomic force
+microscope. Gas sensing measurements provided from resistance measurement in
+the absent and exposure to NO2 gas . The results showed that good enhancement
+of sensitivity take place after doping with tin oxide. Maximum sensitivity
+obtained at 9% doping ratio and operating temperature 200oC.",1808.04235v1
+2018-08-14,High-Pressure Elasticity Tensor from Thermal Diffuse Scattering,"We report on the determination of high-pressure elasticity from thermal
+diffuse x-ray scattering of magnesium oxide at pressures up to 28 GPa. We find
+that the full elasticity tensor as a function of pressure can be extracted from
+x-ray scattering of single crystals. This enables the simultaneous measurement
+of elasticity and crystal structure from a single experiment and thus marks a
+decisive step towards establishing reliable calibration for extreme pressures.
+Elastic constants can be extracted with this method from small crystals of
+arbitrary symmetry, shape and optical properties and will allow for significant
+progress in our understanding of the elastic behaviour of planets interior at
+geophysically relevant conditions, structural phase transitions and fundamental
+interactions of phonons with other quasi-particles.",1808.04595v1
+2018-08-14,"Short commentary on comparing previous claim of RT superconductivity with the data of arXiv:1807.08572, ""Evidence for Superconductivity at Ambient Temperature and Pressure in Nanostructures""","I briefly mention a previous claim of room temperature superconductivity (
+arXiv:0905.3524) in Ag-based oxide material and compare their results with the
+most recent claim of ambient temperature superconductivity in arXiv:1807.08572.
+In both cases, an electrical transition to low resistance state and
+diamagnetism are observed. Silver is a common ingredient in both claims. Does
+it mean that silver holds the key to RT superconductivity or, the missing field
+cool data (in both reports) hint of some other physical phenomenon than
+superconductivity.",1808.04912v1
+2018-08-20,Production of Metal-free Diamond Nanoparticles,"In this paper, the controlled production of high quality metal-free diamond
+nanoparticles is demonstrated. Milling with tempered steel is shown to leave
+behind iron oxide contamination which is difficult to remove. Milling with SiN
+alleviates this issue but generates more non diamond carbon. Thus the choice of
+milling materials is critically determined by the acceptable contaminants in
+the ultimate application. The removal of metal impurities, present in all
+commercially available nanoparticles, will open new possibilities towards the
+production of customised diamond nanoparticles, covering the most demanding
+quantum applications.",1808.06425v1
+2018-12-13,Measuring thickness in thin NbN films for superconducting devices,"We present the use of a commercially available fixed-angle multi-wavelength
+ellipsometer for quickly measuring the thickness of NbN thin films for the
+fabrication and performance improvement of superconducting nanowire single
+photon detectors. The process can determine the optical constants of absorbing
+thin films, removing the need for inaccurate approximations. The tool can be
+used to observe oxidation growth and allows thickness measurements to be
+integrated into the characterization of various fabrication processes.",1812.05559v3
+2018-12-20,"Layer-by-layer resistive switching: multi-state functionality due to electric-field-induced healing of ""dead"" layers","Materials exhibiting reversible resistive switching in electrical fields are
+highly demanded for functional elements in oxide electronics. In particular,
+multilevel switching effects allow for advanced applications like neuromorphic
+circuits. Here we report on a structurally driven switching mechanism involving
+the so-called `dead layers' of perovskite manganite surfaces. Forming a tunnel
+barrier whose thickness can be changed in monolayer steps by electrical fields,
+the switching effect exhibits well-defined and robust resistive states.",1812.08563v1
+2018-12-26,Spin-valve Effect in Nanoscale Si-based Devices,"The silicon (Si) based spin-MOSFET (metal-oxide semiconductor field-effect
+transistor) is considered to be the building block of low-power-consumption
+electronics, utilizing spin-degrees of freedom in semiconductor devices. In
+this paper, we review the latest results on the spin transport in nanoscale
+Si-based spin-valve devices, which is important to realize the nanoscale
+spin-MOSFET. Our results demonstrate the importance of ballistic transport in
+obtaining high spin-dependent output voltage in nanoscale Si spin-valve
+devices.",1812.10210v1
+2019-01-25,Translation-Rotation Coupling in the Dynamics of Linear Molecules in Water,"We study by computer simulations the coupled rotational and translational
+dynamics of three important linear diatomic molecules, namely, carbon monoxide
+(CO), nitric oxide (NO) and cyanide ion (CN-) in water. Translational diffusion
+of these molecules is found to be strongly coupled to their own rotational
+dynamics which in turn are coupled to similar motions of surrounding water. We
+examined the validity of hydrodynamic predictions and found them to be largely
+insufficient, particularly for rotational diffusion. A mode coupling theory
+approach is developed and applied to understand the complexity of
+translation-rotation coupling.",1901.08852v1
+2019-02-19,Topological quantisation and gauge invariance of charge transport in liquid insulators,"According to the Green-Kubo theory of linear response, the conductivity of an
+electronically gapped liquid can be expressed in terms of the time correlations
+of the adiabatic charge flux, which is determined by the atomic velocities and
+Born effective charges. We show that topological quantisation of adiabatic
+charge transport and gauge invariance of transport coefficients allow one to
+rigorously express the electrical conductivity of an insulating fluid in terms
+of integer-valued, scalar, and time-independent atomic oxidation numbers,
+instead of real-valued, tensor, and time-dependent Born charges.",1902.07256v3
+2019-02-23,Optical Properties of Nanoporous Al2O3 Matrices with Ammonium Dihydrogen Phosphate Crystals in Nanopores,"In this paper, the technology of growing ammonium dihydrogen phosphate (ADP)
+crystals in pores of nanoporous aluminum oxide (Al2O3) matrices was presented.
+On the grown nanocomposites, the optical properties of such structures were
+studied. In particular, the direct and diffuse optical transmission, as well as
+specular reflection of Al2O3 matrices with ADP crystals grown in nanopores,
+were analyzed. From the performed experimental studies, it can be concluded
+that the transmission and scattering of pure Al2O3 porous matrices and with ADP
+crystals in nanopores depends largely on the properties of the Al2O3 matrices
+and the technology of their production.",1902.08829v1
+2019-03-08,Ti surface modification for biomedical applications,"Micro Arc Oxidation (MAO) is an electrochemical approach for the surface
+treatment usually applied on so called valve metals such as Al, Mg and Ti. MAO
+is usually carried out an aqueous electrolyte, which involves a bath cooling
+and leads to the creation of surface contained components originated in the
+electrolyte. In current work, we applied a different approach of ceramic
+surface formation on Ti alloy used in biomedical applications. Here, MAO
+process conducted in molten nitrate salt at 280 deg C. The developed surface
+morphology, chemical and phase composition, and corrosion resistance were
+investigated and described in the work.",1903.03507v1
+2019-04-09,MOSFET GIDL Current Variation with Impurity Doping Concentration A Novel Theoretical Approach,"This paper depicts the actual variation of gate induced drain leakage current
+with impurity doping concentration by complete qualitative and quantitative
+approach. De Casteljaus algorithm is applied to describe the band to band
+tunneling in a thin gate oxide nMOSFET and the results are remarkably matched.
+Moreover for the very first time, the dependency of the leakage current over
+impurity density in the MOSFET drain region is explained in the context of pure
+geometrical approach. Surprisingly one of the proportionality constant exactly
+behaves like impurity gradient which results same characteristics as MOSFET
+Drain impurity doping profile measured using 2D simulator.",1904.04827v1
+2019-12-12,Anomalous thermal fluctuation distribution sustains proto-metabolic cycles and biomolecule synthesis,"An environment far from equilibrium is thought to be a necessary condition
+for the origin and persistence of life. In this context we report open-flow
+simulations of a non-enzymic proto-metabolic system, in which hydrogen peroxide
+acts both as oxidant and driver of thermochemical cycling. We find that a
+Gaussian perturbed input produces a non-Boltzmann output fluctuation
+distribution around the mean oscillation maximum. Our main result is that net
+biosynthesis can occur under fluctuating cyclical but not steady drive.
+Consequently we may revise the necessary condition to ""dynamically far from
+equilibrium"".",1912.05781v1
+2020-05-04,Using local GND density to study SCC initiation,"In this work, strain and geometric necessary dislocations (GNDs) have been
+mapped with nm-resolution around grain boundaries affected by stress corrosion
+cracking (SCC) or intergranular oxidation with the aim of clarifying which
+local conditions trigger SCC initiation.",2005.01769v2
+2020-07-03,Complexity matters: highly-accurate numerical models of coupled radiative-conductive heat transfer in a laser flash experiment,"Thermal diffusivity measurements of samples transmitting thermal radiation
+require adjustments to the data treatment procedures in laser flash analysis.
+Conventionally, an unconstrained diathermic model is used. Current results show
+that the alternative coupled radiative-conductive models produce substantially
+different results -- for instance, at high temperatures in oxide ceramics.
+However, care must be taken to ensure accurate implementations of each
+constituent computational technique. The latter are presented in this work.",2008.04079v1
+2020-09-18,Slow decay processes of electrostatically trapped Rydberg NO molecules,"Nitric oxide (NO) molecules initially traveling at 795 m/s in pulsed
+supersonic beams have been photoexcited to long-lived hydrogenic Rydberg-Stark
+states, decelerated and electrostatically trapped in a cryogenically cooled,
+chip-based transmission-line Rydberg-Stark decelerator. The decelerated and
+trapped molecules were detected $in$ $situ$ by pulsed electric field
+ionization. The operation of the decelerator was validated by comparison of the
+experimental data with the results of numerical calculations of particle
+trajectories. Studies of the decay of the trapped molecules on timescales up to
+1 ms provide new insights into the lifetimes of, and effects of blackbody
+radiation on, Rydberg states of NO.",2009.08877v1
+2020-09-26,Suppressing The Ferroelectric Switching Barrier in Hybrid Improper Ferroelectrics,"Integration of ferroelectric materials into novel technological applications
+requires low coercive field materials, and consequently, design strategies to
+reduce the ferroelectric switching barriers. In this first principles study, we
+show that biaxial strain, which has a strong effect on the ferroelectric ground
+states, can also be used to tune the switching barrier of hybrid improper
+ferroelectric Ruddlesden-Popper oxides. We identify the region of the strain --
+tolerance factor phase diagram where this intrinsic barrier is suppressed, and
+show that it can be explained in relation to strain induced phase transitions
+to nonpolar phases.",2009.12486v1
+2020-10-11,2D Surface Phase Diagram of a Multicomponent Perovskite Oxide: La$_{0.8}$Sr$_{0.2}$MnO$_3$(110),"The many surface reconstructions of (110)-oriented lanthanum--strontium
+manganite (La$_{0.8}$Sr$_{0.2}$MnO$_3$, LSMO) were followed as a function of
+the oxygen chemical potential ($\mu_\text{O}$) and the surface cation
+composition. Decreasing $\mu_\text{O}$ causes Mn to migrate across the surface,
+enforcing phase separation into A-site-rich areas and a variety of
+composition-related, structurally diverse B-site-rich reconstructions. The
+composition of these phase-separated structures was quantified with scanning
+tunneling microscopy (STM), and these results were used to build a 2D phase
+diagram of the LSMO(110) equilibrium surface structures.",2010.05205v1
+2020-10-12,Optical and electronic properties in amorphous BaSnO3 thin films,"Wide-bandgap perovskite stannates are of interest for the emergent all-oxide
+transparent electronic devices due to their unparalleled room temperature
+electron mobility. Considering the advantage of amorphous material in
+integrating with non-semiconductor platforms, we herein reported the optical
+and electronic properties in the prototypical stannate, amorphous barium
+stannate (BaSnO3) thin films, which were deposited at room temperature and
+annealed at various temperatures. Despite remaining amorphous status, with
+increasing the annealing temperature, the defect level within amorphous BaSnO3
+thin films could be suppressed.",2010.05580v1
+2020-10-24,Large spin Hall effect in 5d-transition metal anti-perovskites,"The spin Hall effect (SHE) is highly promising for spintronic applications,
+and the design of materials with large SHE can enable ultra-low power memory
+technology. Recently, 5d-transition metal oxides have been shown to demonstrate
+a large SHE. Here we report large values of SHE in four 5d-transition metal
+anti-perovskites which makes these anti-perovskites promising spintronic
+materials. We demonstrate that these effects originate in the mixing of dx2-y2
+and dxy orbitals caused by spin orbit coupling.",2010.12942v1
+2021-02-10,Electromechanical dopant defect interaction in acceptor doped ceria,"Oxygen defective cerium oxides exhibits a non classical giant
+electromechanical response that is superior to lead based electrostrictors. In
+this work, we report the key role of acceptor dopants, with different size and
+valence Mg2+, Sc3+, Gd3+, and La3+, on polycrystalline bulk ceria. Different
+dopants tune the electrostrictive properties by changing the electrosteric
+dopant defect interactions. We find two distinct electromechanical behaviors
+when the interaction is weak dopant vacancy binding energy 0.3 eV,
+electrostriction displays high coefficient, up to 10-17 m2V-2, with strongly
+time dependent effects. In contrast, we observe no time dependent effects when
+the interaction becomes strong 0.6 eV.",2102.05635v1
+2021-02-28,Observation of soft X-ray Cherenkov radiation in Be and Si foils,"Currently, most of the Cherenkov phenomenon researches for the X-ray region
+are theoretical studies; there are only a few experiments in this area. Here
+the new experimental results on observation of X-ray Cherenkov radiation
+generated by 5.7 MeV electrons in the thin Be and Si foils are presented. The
+Cherenkov effect from Be was observed for the first time. The experimental
+results are compared with the calculations performed according to the
+theoretical model of transition radiation taking into account the oxide layer
+on the target output surface.",2103.00579v4
+2021-03-09,Engineering the light coupling between metalens and photonic crystal resonators for robust on-chip microsystems,"We designed an on-chip transformative optic system of a metalens-photonic
+crystal resonator metasystem on a foundry compatible silicon photonic platform.
+By adjusting the on-chip metalens' focusing length and mode dimension, the
+insertion loss between the metalens and the photonic crystal resonator and
+waveguide structures are minimized through mode-matching. The micro-system does
+not involve any single mode silicon nanowire waveguide, and thus mechanically
+robust without any oxide claddings. The proposed microsystem is ideal for
+miniaturized chemical and biosensors operating in air or solution environment.",2103.05580v1
+2021-03-15,Canadian Contributions to the Manhattan Project and Early Nuclear Research,"During the second world war, Canada made several important contributions to
+the wartime work of the Manhattan Project. The three main contributions were:
+establishing a domestic nuclear research laboratory in Montreal to investigate
+heavy water reactors, creating supply chains to provide uranium oxide, heavy
+water and polonium to the Manhattan Project, and the direct contributions of
+several Canadians living the United States. These wartime efforts helped
+establish a legacy of nuclear research in Canada which has persisted to the
+present day.",2103.08582v1
+2021-03-25,Microsphere-coupled light emission control of van der Waals heterostructures,"Two-dimensional transition metal dichalcogenides (TMDCs) integrated to
+photonic structures provide an intriguing playground for the development of
+novel optoelectronic devices with improved performance. Here, we show the
+enhanced light emission from TMDC based van der Waals heterostructures through
+coupling with microsphere cavities. We observe cavity-induced emission
+enhancement of TMDC materials which varies by an order of magnitude, depending
+on the size of the microsphere and thickness of the supporting oxide substrate.
+Furthermore, we demonstrate microsphere cavity-enhanced electroluminescence of
+van der Waals light emitting transistor, showing the potential of 2D material
+based hybrid optoelectronic structures.",2103.13635v1
+2021-04-09,The rise of Single-Atom Catalysts,"In recent years, single-atom catalysts attracted lots of attention because of
+their high catalytic activity, selectivity, stability, maximum atom
+utilization, exceptional performance, and low cost. Single-atom catalyst
+contains isolated individual atom which are coordinated with the surface atoms
+of support such as a metal oxide or 2d - materials. In this review article, we
+present the advancement in single-atom catalysis in recent years with a focus
+on the various synthesis methods and their application in catalytic reactions.
+We also demonstrate the reaction mechanism of a single-atom catalyst for
+different catalytic reactions from theoretical aspects using density functional
+theory.",2104.04370v3
+2021-04-14,"Oxygen hole content, charge-transfer gap, covalency, and cuprate superconductivity","Experiments have shown that the families of cuprate superconductors that have
+the largest transition temperature at optimal doping also have the largest
+oxygen hole content at that doping. They have also shown that a large
+charge-transfer gap, a quantity accessible in the normal state, is detrimental
+to superconductivity. We solve the three-band Hubbard model with cellular
+dynamical mean-field theory and show that both of these observations follow
+from the model. Cuprates play a special role amongst doped charge-transfer
+insulators of transition metal oxides because copper has the largest covalent
+bonding with oxygen.",2104.07087v1
+2021-06-10,Enhanced pairing mechanism in Cuprate-type crystals,"Using a BCS mean-field approach, we show how the interplay between
+low-momentum optical phonons and Jahn-Teller-type lattice distortions can open
+an attractive channel that allows the formation of pairs with the corresponding
+density exhibiting characteristic features of a pair-density wave (PDW). We
+demonstrate this numerically on a copper-oxide type lattice.",2106.05567v2
+2021-06-16,Optical Direct Write of Dolan--Niemeyer-Bridge Junctions for Transmon Qubits,"We characterize highly coherent transmon qubits fabricated with a
+direct-write photolithography system. Multi-layer evaporation and oxidation
+allows us to change the critical current density by reducing the effective
+tunneling area and increasing the barrier thickness. Surface treatments before
+resist application and again before evaporation result in high coherence
+devices. With optimized surface treatments we achieve energy relaxation $T_1$
+times in excess of $80\ \mu$s for three dimensional transmon qubits with
+Josephson junction lithographic areas of 2 $\mu\mathrm{m}^2$.",2106.09034v2
+2021-07-05,Ferroelectric Tunneling Junctions for Edge Computing,"Ferroelectric tunneling junctions (FTJ) are considered to be the
+intrinsically most energy efficient memristors. In this work, specific
+electrical features of ferroelectric hafnium-zirconium oxide based FTJ devices
+are investigated. Moreover, the impact on the design of FTJ-based circuits for
+edge computing applications is discussed by means of two example circuits.",2107.01853v1
+2021-08-08,Threshold switching in solar cells and a no-scribe photovoltaic technology,"We show that thin film CdTe solar cells exhibit the phenomenon of threshold
+switching similar to that in phase change and resistive memory. It creates a
+conductive filament (shunt) through the solar cell reaching the buried
+electrode, such as the transparent conductive oxide (TCO) in CdTe based
+photovoltaics (PV). While in the existing PV the buried electrode was routinely
+contacted via laser scribe filled metals, our work paves a way to an
+alternative technology of no-scribe PV.",2108.03756v3
+2021-08-26,Ferroptosis as a Biological Phase Transition I: avascular and vascular tumor growth,"Herewith we discuss a network model of the ferroptosis avascular and vascular
+tumor growth based on our previous proposed framework. Chiefly, ferroptosis
+should be viewed as a first order phase transition characterized by a
+supercritical Andronov Hopf bifurcation, with the emergence of limit cycle. The
+increase of the population of the oxidized PUFA fragments, take as the control
+parameter, involves an inverse Feigenbaum, (a cascade of saddle foci
+Shilnikov's bifurcations) scenario, which results in the stabilization of the
+dynamics and in a decrease of complexity.",2109.02476v1
+2021-09-27,Orbital entanglement mechanism of superconductivity in cuprates,"We utilize a 1d Hubbard model to show that the superconductivity in cuprate
+superconductors likely arises due to the orbital entanglement between holes in
+the copper oxide plane mediated by orbitally-selective charge hopping. The main
+role of doping required to achieve superconductivity in cuprates is to suppress
+the Mott correlations and orbital ordering. The proposed mechanism explains
+superconductivity in other unconventional superconductors, and provides
+guidance in the search for new high-temperature superconductors.",2109.13019v3
+2021-10-15,Fabrication of Fiber-Reinforced Polymer Ceramic Composites by Wet Electrospinning,"We propose a novel approach of wet electrospinning to yield fiber-reinforced
+polymer ceramic composites, where a reactive ceramic precursor gel is used as a
+collector. We illustrate our approach by generating polyethylene oxide (PEO)
+fibers in a potassium silicate gel; the gel is later activated using metakaolin
+to yield a ceramic-0.5 wt% PEO fiber composite. An increase of 29% and 22% is
+recorded for the fabricated polymer ceramic composites in terms of indentation
+modulus and indentation hardness respectively. Our initial findings demonstrate
+the process viability and might lead to a potentially scalable manufacturing
+approach for fiber-reinforced polymer ceramic composites.",2110.08204v1
+2021-10-27,Ferroelectric control of spin-polarized two-dimensional electron gas,"Spin-polarized two-dimensional electron gas (2DEG) at oxide interfaces is an
+emerging physical phenomenon, which is technologically important for potential
+device applications. However, most previous relevant studies only focused on
+the creation and characterization of the spin-polarized 2DEG. To push forward
+the device applications, the control of spin-polarized 2DEG by electric field
+is an important step. Here, a model system based on antiferromagnetic and
+ferroelectric perovskites, i.e., YTiO3/PbTiO3 superlattice, is designed to
+manipulate the spin-polarized 2DEG. By switching the direction of polarization,
+the spin-polarized 2DEG can be effectively tuned for both symmetric interfaces
+and asymmetric polar interfaces.",2110.14304v1
+2021-11-16,A Machine Learning Model for Predicting Progressive Crack Extension based on DCPD Fatigue Data,"Time history data collected from a Direct Current Potential Drop (DCPD)
+fatigue experiment at a range of temperatures was used to train a Bidirectional
+Long-Short Term Memory Neural Network (BiLSTM) model. The model was trained on
+high sampling rate experimental data from crack initiation up through the Paris
+regime. The BiLSTM model was able to predict the progressive crack extension at
+intermediate temperatures and stress intensities. The model was able to
+reproduce crack jumps and overall crack progression. The BiLSTM model
+demonstrated the potential to be used as a tool for future investigation into
+fundamental mechanisms such as high-temperature oxidation and new damage
+models.",2111.08841v1
+2021-12-09,Projection population analysis for molecules with heavy and superheavy atoms,"A new iterative version of population projection analysis is formulated and
+applied to determine relativistic effective atomic configurations of superheavy
+elements Cn and Fl and their lighter homologues (Hg and Pb) in the molecules of
+their fluorides and oxides. The dependence of the computed populations on the
+initial reference atomic spinors is completely avoided. The difference in
+population of atomic spinors with the same orbital angular momentum and
+different total angular momenta is demonstrated to be essential for
+understanding the peculiarities of chemical bonding in superheavy element
+compounds.",2112.05187v1
+2022-01-14,Two-dimensional electron gas at LaInO$_3$/BaSnO$_3$ interfaces controlled by a ferroelectric layer,"With the example of LaInO$_{3}$/BaSnO$_3$, we demonstrate how both density
+and distribution of a two-dimensional electron gas (2DEG) formed at the
+interface between these perovskite oxides, can be efficiently controlled by a
+ferroelectric functional material. A polarization induced in a BaTiO$_3$ layer
+pointing toward the interface enhances the polar discontinuity which, in turn,
+significantly increases the 2DEG density and confinement, while, the opposite
+polarization depletes the 2DEG. Our predictions and analysis, based on
+first-principles calculations, can serve as a guide for designing such material
+combinations to be used in electronic devices.",2201.05449v1
+2022-02-24,Line-field Coherent Sensing with LED Illumination,"We describe a method of low-coherence interferometry based optical
+profilometry using standard light-emitting diode (LED) illumination and
+complementary metal-oxide-semiconductor (CMOS) image sensors. A line-field
+illumination strategy allows for the simultaneous measurement of many points in
+space. Micron scale accuracy and resolution are achieved and demonstrated using
+a variety of targets.",2202.12161v1
+2022-03-15,High Rate and High Precision Timing and Calorimeter Detectors,"High precision timing, high rate calorimeters, and radiation resistance are
+becoming an important issue in particle physics especially in Energy and
+Intensity Frontiers. We discuss doped Zinc Oxide (ZnO:Ga or GZO; ZnO:X where X
+is Al, Cu or others) as a very fast scintillator and wavelength shifter (WLS),
+Total internal reflection films, and PMT capable of counting at 300 MHz with 10
+ps timing precision, with superior radiation resistance.",2203.09942v1
+2022-06-13,Stability of subnanometer MoS wires under realistic environment,"We carried out first-principles density functional theory calculations of
+hydrogen and oxygen adsorption and diffusion on subnanometer MoS nanowires. The
+nanowires are robust against adsorption of hydrogen. On the other hand,
+interaction with oxygen shows that the nanowires can oxidize with a small
+barrier. Our results open the path for understanding the behavior of MoS
+nanowires under realistic environment.",2206.06342v1
+2022-06-23,Negatively Charged Muonium and Related Centers in Solids,"Muonium (Mu) centers formed upon implantation of $\mu^+$ in a solid have long
+been investigated as an experimentally accessible model of isolated hydrogen
+impurities. Recent discoveries of hydridic centers formed at oxygen vacancies
+have stimulated a renewed interest in H$^-$ and corresponding Mu$^-$ centers in
+oxides. However, the two diamagnetic centers, Mu$^+$ and Mu$^-$, are difficult
+to separate spectroscopically. In this review article, we summarize established
+and developing methodologies for identifying Mu$^-$ centers in solids, and
+review recent Mu studies on said centers supposedly formed in mayenite,
+oxygen-deficient SrTiO$_{3-x}$, and BaTiO$_{3-x}$H$_x$ oxyhydride.",2206.11478v1
+2022-06-23,Metallic delafossite thin films for unique device applications,"Metallic delafossites (ABO2) are layered oxides with quasi-two dimensional
+conduction layers. Metallic delafossites are among the most conducting
+materials with the in-plane conductivity comparable with that of elemental
+metals. In this perspective, we will discuss basic properties and future
+research prospects of metallic delafossites, mainly focusing on thin films and
+heterostructures. We exemplify the fascinating properties of these compounds
+such as high conductivity and surface polarity and discuss how it can be
+utilized in thin films and heterostructures.",2206.11482v1
+2022-07-27,Deposition of the stoichiometric coatings by reactive magnetron sputtering,"The investigations of the reactive magnetron depositing of the stoichiometric
+coatings metal-metalloid were done. The dependences between sputtering
+parameters of a target and processes of plasmochemical formation on the surface
+of sample metal-metalloid and formations of coatings of the appropriate
+structure were investigated. Experimental data on stoichiometric coatings AlN,
+Al2O3, TiN, TiO2 is given. Features of reactive magnetron deposition and
+investigation results for obtaining of coatings with pregiven properties in
+particular for providing stability and controllability of coating deposition
+processes in time. Keywords: reactive magnetron sputtering, coatings, oxide,
+nitride compositions.",2207.13323v1
+2022-08-15,Copper plasmonics with excitons,"We investigate the propagation of surface plasmons (SPPs) in a thin layer of
+copper surrounded by copper oxide Cu$_2$O. It is shown that particularly strong
+excitons in Cu$_2$O can have considerable impact on plasmon propagation,
+providing many opportunities for plasmon-exciton and plasmon-plasmon
+interactions. It is demonstrated that by the use of sufficiently thin metal
+layer, one can excite the so-called long range plasmons (LRSPPs) which can
+overcome the inherently high ohmic losses of Cu as compared to usual plasmonic
+metals such as silver. Analytical results are confirmed by numerical
+calculations.",2208.07184v1
+2022-12-27,Study on the hydrogen behavior in Y and Co doped barium-zirconate,"Hydrogen release behavior from mixed-perovskite oxide, yttrium and cobalt
+doped barium-zirconate, BaZr$_{0.955}$Y$_{0.03}$Co$_{0.015}$O$_{3-a}$ (BZYC)
+exposed to D$_2$ or D$_2$O atmosphere was studied by thermal desorption
+spectroscopy (TDS) detecting deuterium gas (D$_2$) and heavy water vapor
+(D$_2$O) separately. The release of hydrogen appeared at around 1000 K.
+Hydrogen solubility was higher in the BZYC sample exposed to the D$_2$O.",2301.02522v1
+2023-01-09,Edges fractal approach in graphene -- Defects density gain,"Edges fractal approach in graphene e Defects density gain a b s t r a c t To
+optimize the technological development together with energy gain, the crucial
+materials needs to be tailored in a smart way to benefit a maximum from the
+property-structure relation. Herein we propose the way to increase a defect
+density in graphene moving from 1D linear edges to fractal edges, also
+highlight the fractal nature of graphene structures them-self. The tentative
+oxidation and hydrogenation catalytic etching of few layer graphene results in
+structures with edges fractals, jaggy edges at graphene periphery or in newly
+formed etched holes.",2301.03449v1
+2023-01-27,"DFT, L(S)DA, LDA+U, LDA+DMFT..., whether we do approach to a proper description of optical response for strongly correlated systems?","I present a critical overview of so-called ""{\it ab initio}"" DFT (density
+fuctional theory) based calculation schemes for the description of the
+electronic structure, energy spectrum, and optical response for strongly
+correlated 3$d$ oxides, in particular, crystal-field and charge transfer
+transitions as compared with an ""old""\, cluster model that does generalize
+crystal-field and ligand-field theory. As a most instructive illustration of
+validity of numerous calculation techniques I address the prototypical 3$d$
+insulator NiO predicted to be a metal in frames of a standard LDA (local
+density approximation) band theory.",2301.11979v1
+2023-02-10,A short note on the SIMS characterisation of ZnO/Si(100) interface,"The ZnO films, 25 nm thick were deposited by e-beam evaporation of ZnO
+(99.9%) pellets onto native oxide covered silicon (100) substrates. Details of
+the interface chemical composition and the chemical depth profile have been
+deduced as follows: Adsorbed OH surface/OH: ZnO Interface/Pure ZnO thin
+film/ZnO:H: Si Interface/H:SiO2/SiO2/Si(100). The physical profile of the
+crater formed by the SIMS depth profiling was measured with a Tencor P-2
+profilometer as depth profiling showed uniform ion milling and good consistency
+with film thickness (25 nm) measured by SIMS depth profile (25.4 nm).",2302.05306v1
+2023-02-28,A Multimode Hybrid Memristor-CMOS Prototyping Platform Supporting Digital and Analog Projects,"We present an integrated circuit fabricated in a process co-integrating CMOS
+and hafnium-oxide memristor technology, which provides a prototyping platform
+for projects involving memristors. Our circuit includes the periphery circuitry
+for using memristors within digital circuits, as well as an analog mode with
+direct access to memristors. The platform allows optimizing the conditions for
+reading and writing memristors, as well as developing and testing innovative
+memristor-based neuromorphic concepts.",2302.14577v1
+2023-04-17,"Atomistic Wear Mechanisms in Diamond: Effects of Surface Orientation, Stress, and Interaction with Adsorbed Molecules","Despite its unrivaled hardness, diamond can be severely worn during the
+interaction with others, even softer materials. In this work, we calculate from
+first-principles the energy and forces necessary to induce the atomistic wear
+of diamond, and compare them for different surface orientations and passivation
+by oxygen, hydrogen, and water fragments. The primary mechanism of wear is
+identified as the detachment of carbon chains. This is particularly true for
+oxidized diamond and diamond interacting with silica. A very interesting result
+concerns the role of stress, which reveals that compressive stresses can highly
+favor wear, making it even energetically favorable.",2304.08207v1
+2023-04-28,Machine learning-assisted close-set X-ray diffraction phase identification of transition metals,"Machine learning has been applied to the problem of X-ray diffraction phase
+prediction with promising results. In this paper, we describe a method for
+using machine learning to predict crystal structure phases from X-ray
+diffraction data of transition metals and their oxides. We evaluate the
+performance of our method and compare the variety of its settings. Our results
+demonstrate that the proposed machine learning framework achieves competitive
+performance. This demonstrates the potential for machine learning to
+significantly impact the field of X-ray diffraction and crystal structure
+determination. Open-source implementation:
+https://github.com/maxnygma/NeuralXRD.",2305.15410v1
+2023-08-11,Two-dimensional dynamic beam steering by Tamm plasmon polariton,"The dynamic steering of a beam reflected from a photonic structure supporting
+Tamm plasmon polariton is demonstrated. The phase and amplitude of the
+reflected wave are adjusted by modulating the refractive index of a transparent
+conductive oxide layer by applying a bias voltage. It is shown that the
+proposed design allows for two-dimensional beam steering by deflecting the
+light beam along the polar and azimuthal angles.",2308.05910v1
+2023-09-19,Vortex-core spectroscopy of $d$-wave cuprate high-temperature superconductors,"The mechanism of high-temperature superconductivity remains one of the great
+challenges of contemporary physics. Here, we review efforts to image the vortex
+lattice in copper oxide-based high-temperature superconductors and to measure
+the characteristic electronic structure of the vortex core of a $d$-wave
+superconductor using scanning tunneling spectroscopy.",2309.10446v1
+2023-10-16,"1,1-Diphenyl-2-picrylhydrazyl and superoxide anion radical scavenging 1 activities of heterocyclic 2-oxo-1,2,3,4-tetrahydropyrimidines","To investigate1,1-Diphenyl-2-picrylhydrazyl (DPPH) and superoxide radical
+(SOR) 17 scavenging activities of 2-oxo-1,2,3,4-tetrahydropyrimidines
+derivatives. Free radicals are 18 highly unstable and reactive molecules/atoms.
+In the body, free radicals form during 19 normal and abnormal metabolism in the
+body and cause serious damage to other 20 biomolecules through generating
+oxidative stress (OS). If free radicals induced OS does 21 not neutralized
+properly, host multiple pathologies including several types of cancers.",2310.10063v1
+2023-11-10,Revisiting the metal-to-metal transition in $2H$-AgNiO$_2$,"The layered delafossite compound AgNiO$_2$ with $2H$ stacking symmetry
+undergoes a structural metal-to-metal transition at $T_{\rm S}\sim 365$ K. It
+has been described in the past as a charge-ordering transition, where local
+$S=1$ spins are formed on part of the Ni sites. By means of first-principles
+many body calculations, we show that the transition is in fact a site-selective
+Mott transition on the Ni sublattice with only minor charge differentiation.
+Key to this finding is the uncovering of ligand-hole physics, rendering a
+Ni$^{2+}$ instead of a formal Ni$^{3+}$ oxidation state, in conjunction with
+strong local Coulomb repulsions.",2311.06053v1
+2023-12-10,Optimum Design of GaAs/AlGaAs Surface-Relief VCSELs with Single-Mode Operation at 808 nm,"This paper reports an opto-electro-thermal analysis of VCSEL structures with
+a surface-relief filter and different aperture diameters. 808-nm GaAs/AlGaAs
+VCSELs with different aperture diameters and different surface-relief filter
+diameters are studied and the LI curves, the optical spectra, and the
+temperature peaks of the devices are obtained. Also, the impact of utilizing
+different oxide apertures on the temperature peak is shown. The effect of the
+surface-relief filter diameter on VCSEL's performance is also investigated and
+the optimal filter diameter is obtained for maintaining single-mode operation
+while producing as much output power as possible.",2312.07569v1
+2023-12-22,Nanoscale X-ray imaging with high spectral sensitivity using fluorescence intensity correlations,"This paper introduces Spectral Incoherent Diffractive Imaging (SIDI) as a
+novel method for achieving dark-field imaging of nanostructures with
+heterogeneous oxidation states. With SIDI, shifts in photoemission profiles can
+be spatially resolved, enabling the independent imaging of the underlying
+emitter distributions contributing to each spectral line. In the X-ray domain,
+this approach offers unique insights beyond the conventional combination of
+diffraction and X-ray Emission Spectroscopy (XES). When applied at X-ray
+Free-Electron Lasers (XFELs), SIDI promises to be a versatile tool for
+investigating a broad range of systems, offering unprecedented opportunities
+for detailed characterization of heterogeneous nanostructures for catalysis and
+energy storage, including of their ultrafast dynamics.",2312.14602v1
+2023-12-30,Ultrafast X-ray Diffraction Probe of Coherent Spin-state Dynamics in Molecules,"We propose an approach to probe coherent spin-state dynamics of molecules
+using circularly polarized hard x-ray pulses. For the dynamically aligned
+nitric oxide molecules in a coherent superposition spin-orbit coupled
+electronic state that can be prepared through stimulated Raman scattering, we
+demonstrate the capability of ultrafast x-ray diffraction to not only reveal
+the quantum beating of the coherent spin-state wave packet, but also image the
+spatial spin density of the molecule. With circularly polarized ultrafast x-ray
+diffraction signal, we show that the electronic density matrix can be
+retrieved. The spatio-temporal resolving power of ultrafast x-ray diffraction
+paves the way for tracking transient spatial wave function in molecular
+dynamics involving spin degree of freedom.",2401.00259v1
+2024-02-27,Strong Correlations at Oxide Interfaces: What is Hidden in a Plane View?,"A prime goal for this lecture is to provide a reader with a reasonably
+self-sufficient answer to the question of what interesting effects can happen
+if you join two dissimilar materials with correlated carriers to construct a
+sandwich with the interface across those layers. Through the lens of physical
+phenomena, we will delve into the design ideas that lead to the creation of new
+synthetic quantum materials with properties primarily governed by the
+interface.",2403.00015v1
+2024-03-10,Self-heating effect in nanoscale SOI Junctionless FinFET with different geometries,"In this work we study the self-heating (1) effect (SHE) in nanoscale Silicon
+on Insulator Junctionless (SOI JL) FinFET transistor with fi cross section in
+rectangular, trapeze and triangle form. The lattice temperature dependence on
+the channel length as well as on buried oxide thickness is considered. It is
+shown that for considered transistor structure the lattice temperature in the
+middle of the channel is lower than at lateral sides, near source and drain.
+Also, we have found at the same conditions the lattice temperature depends on
+shape of channel cross section too",2403.06271v1
+2024-03-16,Enhanced electron transfer using NiCo2O4@C hollow nanocages with an electron-shuttle effect for efficient tetracycline degradation,"Spinel oxides are recognized as promising Fenton-like catalysts for the
+degradation of antibiotics. However, the catalytic performance is restrained by
+the poor electron transfer rate (ETR). Herein, hollow NiCo2O4@C nanocages are
+rationally designed and prepared to accelerate ETR in peroxymonosulfate (PMS)
+activation for tetracycline (TC) degradation.",2403.10835v1
+2002-04-09,Local Circumstellar Magnetic Fields Around Evolved Stars,"I argue that the presence of magnetic fields around evolved stars, e.g.,
+asymptotic giant branch stars, and in PNe, does not necessarily imply that the
+magnetic field plays a global dynamical role in shaping the circumstellar
+envelope. Instead, I favor magnetic fields with small coherence lengths, which
+result from stellar magnetic spots or from jets blown by an accreting
+companion. Although the magnetic field does not play a global role in shaping
+the circumstellar envelope, it may enhance local motion (turbulent) via
+magnetic tension and reconnection. The locally strong magnetic tension may
+enforce coherence flow which may favor the masing process.",0204157v1
+1995-10-06,Magnetic excitations and effects of magnetic fields on the spin-Peierls transition in CuGeO$_3$,"We analyze the magnetic excitations of a spin-1/2 antiferromagnetic
+Heisenberg model with alternating nearest neighbor interactions and uniform
+second neighbor interactions recently proposed to describe the spin-Peierls
+transition in CuGeO$_3$. We show that there is good agreement between the
+calculated excitation dispersion relation and the experimental one. We have
+also shown that this model reproduces satisfactorily the experimental results
+for the magnetization vs. magnetic field curve and its saturation value. The
+model proposed also reproduces qualitatively some features of the magnetic
+phase diagram of this compound and the overall behavior of the magnetic
+specific heat in the presence of applied magnetic fields.",9509160v1
+1998-02-25,Magnetization Controlled Superconductivity in a Film with Magnetic Dots,"We consider a superconducting film with Magnetic Dots Array (MDA) placed on
+it. Magnetic moments of these dots are supposed to be normal to the film and
+strong enough to create vortices in the superconducting film. Magnetic
+interaction between dots is negligible. Below the superconducting transition
+temperature of the film in zero magnetic field the MDA with randomly magnetized
+dots produces resistive state of the film. Paradoxically, in a finite magnetic
+field the film with MDA is superconductive.",9802276v1
+1999-05-21,Magnetic Field Induced Ordering in Quasi-One-Dimensional Quantum Magnets,"Three-dimensional magnetic ordering transitions are studied theoretically in
+strongly anisotropic quantum magnets. An external magnetic field can drive
+quasi-one-dimensional subsystems with a spin gap into a gapless regime, thus
+inducing long-range three-dimensional magnetic ordering due to weak residual
+magnetic coupling between the subsystems. Compounds with higher spin degrees of
+freedom, such as N-leg spin-1/2 ladders, are shown to have cascades of ordering
+transitions. At high magnetic fields, zero-point fluctuations within the
+quasi-1D subsystems are suppressed, causing quantum corrections to the ordering
+temperature to be reduced.",9905331v1
+2000-04-05,Spin 1/2 Magnetic Impurity in a 2D Magnetic System Close to Quantum Critical Point,"We consider a magnetic impurity in a spin liquid state of a magnetic system
+which is close to the quantum phase transition to the magnetically ordered
+state. There is similarity between this problem and the Kondo problem. We
+derive the impurity Green's function, consider renormalizations of the magnetic
+moments of the impurity, calculate critical indexes for the magnetic
+susceptibilities and finally consider specific heat and magnetic interaction of
+two impurities.",0004057v1
+2000-04-14,Magnetic Field Effects on Neutron Diffraction in the Antiferromagnetic Phase of $UPt_3$,"We discuss possible magnetic structures in UPt$_3$ based on our analysis of
+elastic neutron-scattering experiments in high magnetic fields at temperatures
+$T<T_N$. The existing experimental data can be explained by a single-{\bf q}
+antiferromagnetic structure with three independent domains. For modest in-plane
+spin-orbit interactions, the Zeeman coupling between the antiferromagnetic
+order parameter and the magnetic field induces a rotation of the magnetic
+moments, but not an adjustment of the propagation vector of the magnetic order.
+A triple-{\bf q} magnetic structure is also consistent with neutron
+experiments, but in general leads to a non-uniform magnetization in the
+crystal. New experiments could decide between these structures.",0004253v1
+2001-01-06,Evidence for Adiabatic Magnetization of cold Dy_N Clusters,"Magnetic properties of Dy_N clusters in a molecular beam generated with a
+liquid helium cooled nozzle are investigated by Stern-Gerlach experiments. The
+cluster magnetizations \mu_z are measured as a function of magnetic field (B =
+0 - 1.6T) and cluster size (16 < N < 56). The most important observation is the
+saturation of the magnetization \mu_z(B) at large field strengths. The
+magnetization approaches saturation following the power law |\mu_z-\mu_0|
+proportional to 1/\sqrt{B}, where \mu_0 denotes the magnetic moment. This gives
+evidence for adiabatic magnetization.",0101075v1
+2003-07-08,Asymmetric Lineshape due to Inhomogeneous Broadening of the Crystal-Field Transitions in Mn12ac Single Crystals,"The lineshape of crystal-field transitions in single crystals of Mn12ac
+molecular magnets is determined by the magnetic history. The absorption lines
+are symmetric and Gaussian for the non-magnetized state obtained by zero-field
+cooling (zfc). In the magnetized state which is reached when the sample is
+cooled in a magnetic field (fc), however, they are asymmetric even in the
+absence of an external magnetic field. These observations are quantitatively
+explained by inhomogeneous symmetrical (Gaussian) broadening of the
+crystal-field transitions combined with a contribution of off-diagonal
+components of the magnetic susceptibility to the effective magnetic
+permeability.",0307164v1
+2005-01-17,Frustration effects in magnetic molecules,"By means of exact diagonalization we study the ground-state and the
+low-temperature physics of the Heisenberg antiferromagnet on the cuboctahedron
+and the icosidodecahedron. Both are frustrated magnetic polytopes and
+correspond to the arrangement of magnetic atoms in the magnetic molecules
+Cu12La8 and Mo72Fe30. The interplay of strong quantum fluctuations and
+frustration influences the ground state spin correlations drastically and leads
+to an interesting magnetization process at low temperatures. Furthermore the
+frustration yields low-lying non-magnetic excitations resulting in an extra
+low-temperature peak in the specific heat.",0501376v1
+2005-09-28,About low field memory and negative magnetization in semiconductors and polymers,"Ginzburg-Landau bulk magnetization of itinerant electrons can provide a
+negative effective field in the Weiss model by coupling to localized magnetic
+moments. The coupling enforces remnant magnetization, which can be negative or
+positive depending on the sample magnetic history. Stable magnetic
+susceptibility of coupled nonequilibrium subsystems with magnetization reversal
+is always positive. Gauss-scale fields could be expected for switching between
+negative and positive remnant moments in semiconductors with coupling at
+ambient temperatures. Negative magnetization in ultra-high conducting polymers
+is also discussed within the developed framework.",0509712v1
+2005-10-10,Magnetic dipole-vortex interaction in a bilayer superconductor/soft-magnet heterostructure,"We study the penetration of the nonuniform magnetic field, created by a
+magnetic dipole with out-of-plane magnetization, into a film heterostructure
+composed of a type-II superconductor layer and a soft-magnet layer. In the
+framework of the London approach, the energy of the magnetic dipole-vortex
+interaction is derived and the critical value of the dipole moment for the
+first appearance of a vortex in the superconducting constituent is found for
+two cases of the layer ordering, namely when the dipole is located near the
+superconducting or, respectively, the magnetic constituent.",0510251v1
+2005-10-18,Local field of magnetic islands: role of their shape,"I analyze in details distribution of local magnetic field induced by micro-
+and nano-magnets. I consider three kinds of elongated magnetic islands:
+ellipse-, diamond- and rectangular shaped islands which were magnetized
+uniformly along long axis. This report concentrates on the role of their shape
+upon distribution of the field. Calculations show that unlike
+rectangular-shaped magnet, ellipse-shaped and diamond-shaped ones produce much
+more localized field in proximity of its magnetic poles. Additionally in the
+case of ellipse-shaped islands the magnitude of induced field is large. This
+two facts favor arrays of ellipse-shaped magnetic islands to build
+zero-dimensional spin traps in a hybrid based on Ferromagnet/Semiconductor
+structure.",0510486v1
+2005-11-23,Nonequilibrium Magnetization of a Two-Dimensional Electron Gas in a Static Magnetic Field,"Using a sensitive DC torque magnetometer we measure the orbital magnetization
+by sweeping the density at fixed magnetic fields on GaAs-AlGaAs
+heterostructures. At low temperatures strong nonequilibrium magnetization
+signals dominate the data. In literature the observation of nonequilibrium
+signals are often associated with eddy currents generated by sweeping the
+magnetic field. The elimination of a changing magnetic field then poses a
+question regarding the origin of these signals. Our data suggests another
+source of nonequilibrium magnetization potentially due to the change of area
+occupied by compressible and incompressible states as one sweeps the Fermi
+energy from one Landau level to the next.",0511569v1
+2006-04-01,Magnetization reversal through synchronization with a microwave,"Based on the Landau-Lifshitz-Gilbert equation, it can be shown that a
+circularly-polarized microwave can reverse the magnetization of a Stoner
+particle through synchronization. In comparison with magnetization reversal
+induced by a static magnetic field, it can be shown that when a proper
+microwave frequency is used the minimal switching field is much smaller than
+that of precessional magnetization reversal. A microwave needs only to overcome
+the energy dissipation of a Stoner particle in order to reverse magnetization
+unlike the conventional method with a static magnetic field where the switching
+field must be of the order of magnetic anisotropy.",0604013v1
+2006-05-01,Possible magnetic-field-induced voltage and thermopower in diluted magnetic semiconductors,"In diluted magnetic semiconductors, the carrier concentration and the
+magnetization of local moments are strongly coupled, since the magnetic
+interaction is mediated by the carriers. It is predicted that this coupling
+leads to an electric polarization due to an applied magnetic-field gradient and
+to the appearance of a magnetic-field-dependent voltage. An expression for this
+voltage is derived within Landau theory and its magnitude is estimated for
+(Ga,Mn)As. Furthermore, a large contribution to the thermopower based on the
+same mechanism is predicted. The role of fluctuations is also discussed. These
+predictions hold both if the magnetization is uniform and if it shows
+stripe-like modulations, which are possible at lower temperatures.",0605043v1
+2006-05-22,Kondo-transport spectroscopy of single molecule magnets,"We demonstrate that in a single molecule magnet (SMM) strongly coupled to
+electrodes the Kondo effect involves all magnetic excitations. This Kondo
+effect is induced by the quantum tunneling of the magnetic moment (QTM).
+Importantly, the Kondo temperature $T_K$ can be much larger than the magnetic
+splittings. We find a strong modulation of the Kondo effect as function of the
+transverse anisotropy parameter or a longitudinal magnetic field. For both
+integer and half-integer spin this can be used for an accurate transport
+spectroscopy of the magnetic states in low magnetic fields on the order of the
+easy-axis anisotropy parameter. We set up a relationship between the Kondo
+effects for successive integer and half-integer spins.",0605514v1
+2006-07-19,Magnetic-Field Induced Gap in One-Dimensional Antiferromagnet KCuGaF$_6$,"Magnetic susceptibility and specific heat measurements in magnetic fields
+were performed on an $S=1/2$ one-dimensional antiferromagnet KCuGaF$_6$.
+Exchange interaction was evaluated as $J/k_{\rm B}\simeq 100$ K. However, no
+magnetic ordering was observed down to 0.46 K. It was found that an applied
+magnetic field induces a staggered magnetic susceptibility obeying the Curie
+law and an excitation gap, both of which should be attributed to the
+antisymmetric interaction of the Dzyaloshinsky-Moriya type and/or the staggered
+$g$-tensor. With increasing magnetic field $H$, the gap increases almost in
+proportion to $H^{2/3}$.",0607469v1
+1998-11-18,Magnetic field profiling for selected-states magnetic-resonance spectroscopy (SSMRS) and Stern-Gerlach spectroscopy (MGRS) in condensed matter,"A method was presented of profiling the magnetic field, with a zero vector of
+magnetic flux density $B_{r}$ and strong gradient G, enabling conditions for
+the Stern-Gerlach spectroscopy to be accomplished in condensed matter (the
+method has been called magnetic field gradient spectroscopy - MGRS), as well
+the previously proposed magnetic resonance spectroscopy for selected energy
+states (SSMRS). Magnetic field distribution in a model electromagnet were shown
+when condition $B_{r}= 0$ for resultant magnetic field was satisfied within the
+sample",9811034v1
+2007-08-22,Neutron channelling in a magnetic tube trap,Neutron channelling in a magnetic tube trap is discussed,0708.3042v1
+2007-11-13,Magnetic nanowires as permanent magnet materials,"We present the fabrication of metallic magnetic nanowires using a low
+temperature chemical process. We show that pressed powders and magnetically
+oriented samples exhibit a very high coercivity (6.5 kOe at 140 K and 4.8 kOe
+at 300 K). We discuss the magnetic properties of these metamaterials and show
+that they have the suitable properties to realize ""high temperature magnets""
+competitive with AlNiCo or SmCo permanent magnets. They could also be used as
+recording media for high density magnetic recording.",0711.1978v1
+2008-06-28,Effect of magnetization and magnetic field variation on stationary axisymmetric equilibrium,"The inclusion of plasma magnetization in the equations of stationary
+equilibrium is derived, and its effect on the determination of axisymmetric
+equilibrium calculated. A factor of 2 on the pressure gradient arises in the
+equilibrium equation from the force felt by the dipole moment density. The
+algebraic and differential equation formulations are compared both with and
+without consideration of magnetization, revealing the effects of both
+magnetization and magnetic field variation on the equilibrium, which become
+more pronounced for high pressures in a weak external field. The equivalence of
+the magnetized equilibrium equation with the standard equilibrium equation in
+the limit of vanishing magnetization is demonstrated.",0806.4696v2
+2008-10-07,Multiple magnetic barriers in graphene,"We study the behavior of charge carriers in graphene in inhomogeneous
+perpendicular magnetic fields. We consider two types of one-dimensional
+magnetic profiles, uniform in one direction: a sequence of N magnetic barriers,
+and a sequence of alternating magnetic barriers and wells. In both cases, we
+compute the transmission coefficient of the magnetic structure by means of the
+transfer matrix formalism, and the associated conductance. In the first case
+the structure becomes increasingly transparent upon increasing N at fixed total
+magnetic flux. In the second case we find strong wave-vector filtering and
+resonant effects. We also calculate the band structure of a periodic magnetic
+superlattice, and find a wave-vector-dependent gap around zero-energy.",0810.1236v1
+2008-12-10,Magnetic monopole and the nature of the static magnetic field,"We investigate the factuality of the hypothetical magnetic monopole and the
+nature of the static magnetic field. It is shown from many aspects that the
+concept of the massive magnetic monopoles clearly is physically untrue. We
+argue that the static magnetic field of a bar magnet, in fact, is the static
+electric field of the periodically quasi-one-dimensional electric-dipole
+superlattice, which can be well established in some transition metals with the
+localized d-electron. This research may shed light on the perfect unification
+of magnetic and electrical phenomena.",0812.2048v1
+2010-04-15,Magnetization Process of Kagome-Lattice Heisenberg Antiferromagnet,"The magnetization process of the isotropic Heisenberg antiferromagnet on the
+kagome lattice is studied. Data obtained from the numerical-diagonalization
+method are reexamined from the viewpoint of the derivative of the magnetization
+with respect to the magnetic field. We find that the behavior of the derivative
+at approximately one-third of the height of the magnetization saturation is
+markedly different from that for the cases of typical magnetization plateaux.
+The magnetization process of the kagome-lattice antiferromagnet reveals a new
+phenomenon, which we call the ""magnetization ramp"".",1004.2528v1
+2011-07-14,Magnetic instability induced by tunnel current in single Co nanoparticles,"Measurements of magnetic hysteresis loops in single Co nanoparticles at
+dilution refrigerator temperatures are presented. The nanoparticles are in
+electric contact with bulk Al leads via tunnel junctions. The tunnel current
+versus magnetic field displays a magnetic hysteresis loop. The magnetic
+switching field is reduced by current, and the magnetization of the
+nanoparticle can be switched by applying a voltage pulse, demonstrating that
+the magnetic stability of the nanoparticle is diminished by electron transport.
+Additional transitions and random switches of magnetization can be driven by
+large currents.",1107.2850v3
+2011-08-09,"Magnetic phases of a highly frustrated magnet, ZnCr2O4, up to an ultra-high magnetic field of 600 T","The Faraday rotation and magneto-optical absorption spectral measurements
+were conducted to reveal the full-magnetization process and map out a magnetic
+phase diagram of a typical geometrical frustrated magnet, ZnCr2O4, by using the
+electromagnetic flux compression method in ultra-magnetic fields up to 600 T. A
+fully polarized ferromagnetic phase is observed in which the absorption spectra
+associated with an exciton-magnon-phonon transition disappears. Furthermore,
+prior to the fully polarized ferromagnetic phase above 410 T, we found a novel
+magnetic phase above 350 T followed by a canted 3:1 phase.",1108.1932v1
+2012-03-21,Percolation and orientational ordering in systems of magnetic nanorods,"Based on Monte Carlo (MC) computer simulations we study the structure
+formation of a system of magnetic nanorods. Our model particles consist of
+fused spheres with permanent magnetic dipole moments, as inspired by recent
+experiments. The resulting system behaves significantly different from a system
+of hard (non-magnetic) rods or magnetic rods with a single longitudinal dipole.
+In particular, we observe for the magnetic nanorods a significant decrease of
+the percolation threshold (as compared to non-magnetic rods) at low densities,
+and a stabilization of the high-density nematic phase. Moreover, the
+percolation threshold is tunable by an external magnetic field.",1203.4707v1
+2012-07-10,Micromagnetic simulation of magnetic small-angle neutron scattering from two-phase nanocomposites,"The recent development of a micromagnetic simulation methodology - suitable
+for multiphase magnetic nanocomposites - permits the computation of the
+magnetic microstructure and of the associated magnetic small-angle neutron
+scattering (SANS) cross section of these materials. In this review article we
+summarize results on the micromagnetic simulation of magnetic SANS from
+two-phase nanocomposites. The decisive advantage of this approach resides in
+the possibility to srutinize the individual magnetization Fourier contributions
+to the total magnetic SANS cross section, rather than their sum, which is
+generally obtained from experiment. The procedure furnishes unique and
+fundamental information regarding magnetic neutron scattering from nanomagnets.",1207.2331v1
+2013-04-10,A proposed new route to d0 magnetism in semiconductors,"Here we propose to induce magnetism in semiconductor utilizing the unique
+properties of the interstitial defect to act as the magnetic impurity within
+the alpha-PbO crystal structure. The Pbi interstitial generates the p-localized
+state with two on-site electrons to obey the Hund's rule for their ordering. It
+is demonstrated that instead of Pb interstitial other non-magnetic impurities
+of s^2p^{x} outer shell configuration can be applied to induce d0 magnetism
+with possibility to tune the local magnetic moments mu_B by varying a number of
+electrons 1< x< 3. The magnetic coupling between such defects is found to be
+driven by the long-range order interactions that in combination with high
+defect solubility promises the magnetic percolation to remain above the room
+temperature.",1304.2945v1
+2013-10-23,Magnetization Characteristic of Ferromagnetic Thin Strip by Measuring Anisotropic Magnetoresistance and Ferromagnetic Resonance,"The magnetization characteristic in a permalloy thin strip is investigated by
+electrically measuring the anisotropic magnetoresistance and ferromagnetic
+resonance in in-plane and out-of-plane configurations. Our results indicate
+that the magnetization vector can rotate in the film plane as well as out of
+the film plane by changing the intensity of external magnetic field of certain
+direction. The magnetization characteristic can be explained by considering
+demagnetization and magnetic anisotropy. Our method can be used to obtain the
+demagnetization factor, saturated magnetic moment and the magnetic anisotropy.",1310.6117v1
+2013-11-21,A new Approach for Magnetic Curves in 3D Riemannian Manifolds,"A magnetic field is defined by the property that its divergence is zero in a
+three dimensional oriented Riemannian manifold. Each magnetic field generates a
+magnetic flow whose trajectories are curves called as magnetic curves. In this
+paper, we give a new variational approach to studies the magnetic flow
+asociated with the Killing magnetic field in a three dimensional oriented
+Riemann manifold, And then, we investigate the trajectories of the magnetic
+fields called as N-magnetic and B-magnetic curves.",1311.5348v3
+2014-07-01,Explaining Mercury's Density through Magnetic Erosion,"In protoplanetary disks, dust grains rich in metallic iron can attract each
+other magnetically. If they are magnetized to values near saturation, the
+magnetically induced collision speeds are high enough to knock off the
+non-magnetized, loosely bound silicates. This process enriches the surviving
+portions of the dust grains in metallic iron, which further enhances the
+magnetically mediated collisions. The magnetic enhancement to the collisional
+cross-section between the iron rich dust results in rapid grain growth leading
+to planetesimal formation. While this process of knocking off silicates, which
+we term ""magnetic erosion"", occurs only in a very limited portion of a
+protoplanetary disk, it is a possible explanation for Mercury's
+disproportionately large iron core.",1407.0274v1
+2014-09-25,Atomistic simulation of sub-nanosecond non-equilibrium field cooling processes for magnetic data storage applications,"Thermally assisted magnetic writing is an important technology utilizing
+temperature dependent magnetic properties to enable orientation of a magnetic
+data storage medium. Using an atomistic spin model we study non-equilibrium
+field cooled magnetization processes on sub-nanosecond timescales required for
+device applications. We encapsulate the essential physics of the process in a
+TRM-T curve and show that for fast timescales heating to the Curie temperature
+is necessary where the magnetic relaxation time is shortest. Furthermore we
+demonstrate the requirement for large magnetic fields to achieve a high
+thermoremanent magnetization necessary for fast recording or data rates.",1409.7377v1
+2015-07-22,Magnetic Response Functions in Landau Levels,"We propose a new quantization rule which generates Landau levels consistent
+with the zero-field magnetic response functions from the semiclassical theory.
+It reproduces the Onsager's rule in the leading order, and re-formulates
+corrections from the Berry phase and magnetic moment effect in terms of one
+single magnetic response: the zero-field magnetization. It can yield higher
+order corrections by including successively magnetic susceptibility and higher
+order magnetic response functions. In application, it can be easily applied to
+obtain Landau levels in lattice models. Moreover, it provides an experimental
+method of measuring different magnetic response functions directly from the
+measurement of Landau level fan diagram or Hofstadter spectrum.",1507.06342v2
+2016-02-29,Gyrotropic skyrmion modes in ultrathin magnetic circular dots,"We calculate low-frequency gyrotropic spin excitation modes of the skyrmion
+ground state ultrathin cylindrical magnetic dots. The skyrmion is assumed to be
+stabilized at room temperature and zero external magnetic field due to an
+interplay of the isotropic and Dzyaloshinskii-Moriya exchange interactions,
+perpendicular magnetic anisotropy and magnetostatic interaction. We consider
+Bloch- and Neel-type magnetic skyrmions and assume that the dot magnetization
+does not depend on the thickness coordinate. The skyrmion gyrotropic
+frequencies are calculated in GHz range as a function of the skyrmion
+equilibrium radius, dot radius and the dot magnetic parameters. Recent
+experiments on magnetic skyrmion gyrotropic dynamics in nanodots are discussed.",1603.00072v1
+2016-04-05,Incommensurate Magnetic Structure in the Cubic Noncentrosymmetric Ternary Compound Pr5Ru3Al2,"We performed magnetic susceptibility and neutron powder diffraction
+experiments on the ternary compound Pr5Ru3Al2. It belongs to the
+noncentrosymmetric and nonmirrorsymmetric cubic I213 space group. The
+previously reported ferromagnetic transition at 24 K was not detected in our
+improved quality samples. Instead, magnetic ordering was observed in the DC
+magnetic susceptibility at 3.8 K. Neutron powder diffraction further indicates
+that an incommensurate magnetic structure is established below 3.8 K, with the
+magnetic modulation vector (0.066, 0.066, 0.066) (r.l.u.). Using the magnetic
+representation analysis, we propose the block helical structure as a candidate
+for the incommensurate magnetic structure.",1604.01149v1
+2016-06-08,Magnetic energy of sc ferromagnetic films with three layers as described by third order perturbed Heisenberg Hamiltonian,"The solution of third order perturbed Heisenberg Hamiltonian of simple cubic
+ferromagnetic ultra-thin films with three layers were found. All the magnetic
+energy parameters such as spin exchange interaction, magnetic dipole
+interaction, second order magnetic anisotropy, fourth order magnetic
+anisotropy, applied magnetic field, demagnetization factor and stress induced
+anisotropy were included in the third order perturbed Heisenberg Hamiltonian.
+3-D plots of stress induced anisotropy, out of plane magnetic field,
+demagnetization factor and spin exchange interaction are presented in this
+manuscript. Magnetic easy and hard directions were determined using these 3-D
+plots. MATLAB program was employed to solve the equation with seven parameters.",1606.02439v1
+2016-07-19,MHD flow and heat transfer due to the axisymmetric stretching of a sheet with induced magnetic field,"The full MHD equations, governing the flow due to the axisymmetric stretching
+of a sheet in the presence of a transverse magnetic field, can be cast in a
+self similar form. This allows evaluation of the induced magnetic field and its
+effect on the flow and heat transfer. The problem involves three parameters-
+the magnetic Prandtl number, the magnetic interaction number, and the Prandtl
+number. Numerical solutions are obtained for the velocity field, the magnetic
+field, and the temperature, at different values of the magnetic Prandtl number
+and the magnetic interaction number. The contributions of the viscous
+dissipation, Joule heating, and streamwise diffusion to the heat flux toward
+the sheet are assessed.",1607.05722v1
+2017-02-27,Magnetization reversal by superconducting current in $\varphi_0$ Josephson junctions,"We study magnetization reversal in a $\varphi_0$ Josephson junction with
+direct coupling between magnetic moment and Josephson current. Our simulations
+of magnetic moment dynamics show that by applying an electric current pulse, we
+can realize the full magnetization reversal. We propose different protocols of
+full magnetization reversal based on the variation of the Josephson junction
+and pulse parameters, particularly, electric current pulse amplitude, damping
+of magnetization and spin-orbit interaction. We discuss experiments which can
+probe the magnetization reversal in $\varphi_0$-junctions.",1702.08394v4
+2014-03-13,Monte Carlo simulated dynamical magnetization of single-chain magnets,"Here, a dynamical Monte-Carlo (DMC) method is used to study
+temperature-dependent dynamical magnetization of famous Mn2Ni system as typical
+example of single-chain magnets with strong magnetic anisotropy. Simulated
+magnetization curves are in good agreement with experimental results under
+typical temperatures and sweeping rates, and simulated coercive fields as
+functions of temperature are also consistent with experimental curves. Further
+analysis indicates that the magnetization reversal is determined by both
+thermal-activated effects and quantum spin tunnelings. These can help explore
+basic properties and applications of such important magnetic systems.",1403.3188v2
+2016-11-14,Magnetization process and magnetocaloric effect of the spin-1/2 XXZ Heisenberg cuboctahedron,"Magnetic properties of the spin-1/2 XXZ Heisenberg cuboctahedron are examined
+using exact numerical diagonalization depending on a relative strength of the
+exchange anisotropy. While the Ising cuboctahedron exhibits in a
+low-temperature magnetization curve only one-third magnetization plateau, the
+XXZ Heisenberg cuboctahedron displays another four intermediate plateaux at
+zero, one-sixth, one-half and two-thirds of the saturation magnetization. The
+novel magnetization plateaux generally extend over a wider range of magnetic
+fields with increasing of a quantum ($xy$) part of the XXZ exchange
+interaction. It is shown that the XXZ Heisenberg cuboctahedron exhibits in a
+vicinity of all magnetization jumps anomalous thermodynamic behavior
+accompanied with an enhanced magnetocaloric effect.",1611.04301v1
+2018-05-24,Searching the weakest link: Demagnetizing fields and magnetization reversal in permanent magnets,"Magnetization reversal in permanent magnets occurs by the nucleation and
+expansion of reversed domains. Micromagnetic theory offers the possibility to
+localize the spots within the complex structure of the magnet where
+magnetization reversal starts. We compute maps of the local nucleation field in
+a Nd2Fe14B permanent magnet using a model order reduction approach. Considering
+thermal fluctuations in numerical micromagnetics we can also quantify the
+reduction of the coercive field due to thermal activation. However, the major
+reduction of the coercive field is caused by the soft magnetic grain boundary
+phases and misorientation if there is no surface damage.",1805.09798v1
+2012-01-04,Origin of training effect of exchange bias in Co/CoO due to irreversible thermoremanent magnetization of the magnetically diluted antiferromagnet,"The irreversible thermoremanent magnetization of a sole, magnetically diluted
+epitaxial antiferromagnetic Co$_{1-y}$O(100) layer is determined by the mean of
+its thermoremanent magnetizations at positive and negative remanence. During
+hysteresis-loop field cycling, thermoremanent magnetization exhibits successive
+reductions, consistent with the training effect (TE) of the exchange bias
+measured for the corresponding Co$_{1-y}$O(100)/Co bilayer. The TE of exchange
+bias is shown to have its microscopic origin in the TE of the irreversible
+thermoremanent magnetization of the magnetically diluted AFM.",1201.0831v1
+2018-01-09,Magneto-electric effect in doped magnetic ferroelectrics,"We propose a model of magneto-electric effect in doped magnetic
+ferroelectrics. This magneto-electric effect does not involve the spin-orbit
+coupling and is based purely on the Coulomb interaction. We calculate magnetic
+phase diagram of doped magnetic ferroelectrics. We show that magneto-electric
+coupling is pronounced only for ferroelectrics with low dielectric constant. We
+find that magneto-electric coupling leads to modification of magnetization
+temperature dependence in the vicinity of ferroelectric phase transition. A
+peak of magnetization appears. We find that magnetization of doped magnetic
+ferroelectrics strongly depends on applied electric field.",1801.03114v1
+2019-06-04,Deterministic magnetization switching by voltage-control of magnetic anisotropy and Dzyaloshinskii-Moriya interaction under in-plane magnetic field,"Based on the micromagnetic simulations the magnetization switching in a
+triangle magnetic element by voltage-control of magnetic anisotropy and
+Dzyaloshinskii-Moriya interaction under in-plane magnetic field is proposed.
+The proposed switching scheme is not the toggle switching but the deterministic
+switching where the magnetic state is determined by the polarity of the applied
+voltage pulse. The mechanism and conditions for the switching are clarified.
+The results provide a fast and low-power writing method for magnetoresistive
+random access memories.",1906.01254v1
+2019-06-14,Friedel oscillations in 2D electron gas from spin-orbit interaction in a parallel magnetic field,"Effects associated with the interference of electron waves around a magnetic
+point defect in two-dimensional electron gas with combined Rashba-Dresselhaus
+spin-orbit interaction in the presence of a parallel magnetic field are
+theoretically investigated. The effect of a magnetic field on the anisotropic
+spatial distribution of the local density of states and the local density of
+magnetization is analyzed. The existence of oscillations of the density of
+magnetization with scattering by a non-magnetic defect and the contribution of
+magnetic scattering (accompanied by spin-flip) in the local density of electron
+states are predicted.",1906.06043v1
+2019-06-21,Magnetic lattices for ultracold atoms,"This article reviews the development in our laboratory of magnetic lattices
+comprising periodic arrays of magnetic microtraps created by patterned magnetic
+films to trap periodic arrays of ultracold atoms. Recent achievements include
+the realisation of multiple Bose-Einstein condensates in a 10 micron-period
+one-dimensional magnetic lattice; the fabrication of sub-micron-period square
+and triangular magnetic lattice structures suitable for quantum tunnelling
+experiments; the trapping of ultracold atoms in a sub-micron-period triangular
+magnetic lattice; and a proposal to use long-range interacting Rydberg atoms to
+achieve spin-spin interactions between sites in a large-spacing magnetic
+lattice.",1906.08918v1
+2017-05-16,An approach to 1000 T using the Electro-Magnetic Flux Compression,"An ultra-high magnetic field was generated by the electro-magnetic flux
+compression technique under a reduced seed magnetic field condition and
+achieved maximum magnetic field intensity was investigated. An ordinal pickup
+coil measurement fails due to the dielectric breakdown at around 500 T. On the
+other hand, by utilizing the magneto-optical Faraday rotation method with a
+small probe, the measureable maximum magnetic field increased significantly. It
+was found that reduced seed field increases the maximum magnetic field, but
+with a reduced size of the final bore. A highest magnetic field over 763 T and
+possibly up to 985 T approaching 1000 T was detected.",1705.05520v1
+2018-03-03,Long Range Magnetic order stabilized by acceptors,"Tuning magnetic order in magnetic semiconductors is a long sought goal. A
+proper concentration of acceptors can dramatically suppress local magnetic
+order in favor of the long one. Using Mn and an acceptor codoped LiZnAs as an
+example, we demonstrate, by first-principles calculation, the emergence of a
+long-range magnetic order. This intriguing phenomenon can be understood from an
+interplay between an acceptor-free magnetism and a band coupling magnetism. Our
+observation thus lays the ground for a precise control of the magnetic order in
+future spintronic devices.",1803.01179v1
+2020-08-26,A Magnetic Velocity Verlet Method,"We discuss an extension of the velocity Verlet method that accurately
+approximates the kinetic-energy-conserving charged particle motion that comes
+from magnetic forcing. For a uniform magnetic field, the method is shown to
+conserve both particle kinetic energy and magnetic dipole moment better than
+midpoint Runge-Kutta. We then use the magnetic velocity Verlet method to
+generate trapped particle trajectories, both in a cylindrical magnetic mirror
+machine setup, and for dipolar fields like the earth's magnetic field. Finally,
+the method is used to compute an example of (single) mirror motion in the
+presence of a magnetic monopole field, where the trajectory can be described in
+closed form.",2008.11810v1
+2021-02-26,Distinctive magnetic properties of CrI3 and CrBr3 monolayers caused by spin-orbit coupling,"After the discovery of magnetism in monolayer CrI3, the magnetic properties
+of different 2D materials from the chromium-trihalide family are intuitively
+assumed to be similar, yielding magnetic anisotropy from the spin-orbit
+coupling on halide ligands. Here we reveal significant differences between the
+CrI3 and CrBr3 magnetic monolayers in their magnetic anisotropy, resulting
+Curie temperature, hysteresis in external magnetic field, and evolution of
+magnetism with strain, all predominantly attributed to distinctly different
+interplay of atomic contributions to spin-orbit coupling in two materials.",2102.13325v1
+2021-06-01,Impact of magnetic domains on magnetic flux concentrators,"The impact of magnetic domains in magnetic flux concentrators is studied
+using the simulation software MuMax3. First, the simulation parameters are
+validated using experimental results from magnetic force microscopy; second the
+simulation output is benchmarked with the one obtained using Comsol
+Multiphysics. Finally, the impact of magnetic domain is assessed, showing how
+micromagnetic effects can become relevant, if not dominant, when scaling the
+gap between the MFC and the sensor.",2106.00370v2
+2021-10-16,A stretched exponential-based approach for the magnetic properties of spin glasses,"The spin glasses show intriguing characteristic features that are not well
+understood yet, as for instance its aging, rejuvenation and memory effects.
+Here a model based on a stretched exponential decay of its magnetization is
+proposed, which can describe the main magnetic features of spin glasses
+observed in experiments as the time-decay of thermoremament magnetization, the
+relaxation of zero field cooled magnetization, the ac and dc magnetization as a
+function of temperature and others. In principle, the here proposed model could
+be adapted to describe other glassy systems.",2110.08625v2
+2021-12-06,Magnetism of two-dimensional magnets in the presence of random fields,"In low-dimensional magnets, thermal agitation and spatial disorders generate
+strong spin fluctuations that suppress the long-range magnetic ordering. We
+develop an analytical equation for the equilibrium magnetization of
+two-dimensional magnets at finite temperatures in the presence of the random
+magnetic field. We find that the random field induces a first-order phase
+transition in addition to the reduced Curie temperature. The first-order phase
+transition persists even in the presence of the moderate external magnetic
+field.",2112.03343v1
+2022-04-11,Deformation of a magnetic liquid drop and unsteady flow inside and outside it in a non-stationary magnetic field,"Small steady-state deformational oscillations of a drop of a viscous magnetic
+liquid in a non-stationary uniform magnetic field are theoretically
+investigated for low Reynolds numbers. The drop is suspended in another viscous
+magnetic liquid immiscible with the former. The non-stationary magnetic field
+causes flow inside and outside the drop. The inertia is taken into account by
+regarding the flow as essentially unsteady. The variation of the magnetic field
+is so slow that the approximation of quasi-stationary magnetic field may be
+used.",2204.05387v2
+2022-10-06,MagNet: machine learning enhanced three-dimensional magnetic reconstruction,"Three-dimensional (3D) magnetic reconstruction is vital to the study of novel
+magnetic materials for 3D spintronics. Vector field electron tomography (VFET)
+is a major in house tool to achieve that. However, conventional VFET
+reconstruction exhibits significant artefacts due to the unavoidable presence
+of missing wedges. In this article, we propose a deep-learning enhanced VFET
+method to address this issue. A magnetic textures library is built by
+micromagnetic simulations. MagNet, an U-shaped convolutional neural network, is
+trained and tested with dataset generated from the library. We demonstrate that
+MagNet outperforms conventional VFET under missing wedge. Quality of
+reconstructed magnetic induction fields is significantly improved.",2210.03066v1
+2022-10-30,Controlling magnetic anisotropy in amplitude expansion of phase field crystal model,"The amplitude expansion for a magnetic phase-field-crystal (magnetic APFC)
+model enables a convenient coarse-grained description of crystalline structures
+under the influence of magnetic fields. Considering higher-order magnetic
+coupling terms, we demonstrate the possibility of tuning the magnetic
+anisotropy in these models. This allows for reproducing the easy and hard
+direction of magnetization. Such a result can be achieved without increasing
+the computational cost, enabling simulations of the manipulation of dislocation
+networks and microstructures in ferromagnetic materials. As a demonstration, we
+report on the simulation of the shrinkage of a spherical grain with the
+magnetic anisotropy of Fe.",2210.16855v1
+2023-12-13,Enhanced Magnetic Field Amplification by Ion-Beam Weibel Instability in Weakly Magnetized Astrophysical Shocks,"We examine the evolution of ion-beam Weibel instability at strong
+collisionless shocks in weakly magnetized media. We find that a finite
+background magnetic field substantially affects both linear and nonlinear
+phases of the instability, depending on whether the background electrons behave
+magnetized or not. Particle-in-cell simulations for magnetized electrons
+identify a dynamo-like mechanism of magnetic field amplification, which
+eventually leads to spontaneous magnetic reconnection. We conclude that this
+scenario is applicable to typical young supernova remnant shocks.",2312.07933v1
+2019-11-14,Real time observation of a stationary magneton,"The magnetic dipole field geometry of subatomic elementary particles like the
+electron differs from the classical macroscopic field imprint of a bar magnet.
+It resembles more like an eight figure or else joint double quantum-dots
+instead of the classical, spherical more uniform field of a bar magnet. This
+actual subatomic quantum magnetic field of an electron at rest, is called
+Quantum Magnet or else a Magneton. Normally, a macroscale bar magnet should
+behave like a relative giant Quantum Magnet with identical magnetic dipole
+field imprint since all of its individual magnetons collectively inside the
+material, dipole moments are uniformly aligned forming the total net field of
+the magnet. However due to Quantum Decoherence (QDE) phenomenon at the
+macroscale and macroscopic magnetic field imaging sensors limitations which
+cannot pickup these rapid quantum magnetization fluctuations, this field is
+masked and not visible at the macroscale. By using the relative inexpensive
+submicron resolution Ferrolens quantum magnetic optical sensor and method, we
+can actually make this net magneton field visible on macroscale magnets. We
+call this net total field herein, Quantum Field of Magnet (QFM) differentiating
+it therefore from the field of the single subatomic magneton thus quantum
+magnet. Additionally, the unique potential of the Ferrolens device to display
+also the magnetic flux lines of this macroscopically projected giant Magenton
+gives us the unique opportunity to study the individual magnetic flux lines
+geometrical pattern that of a single subatomic magneton. We describe this
+particular magnetic flux of the magneton observed, quantum magnetic flux.
+Therefore a novel observation has been made that the QFM of the Magnet-Magneton
+consists of a dipole vortex shaped magnetic flux geometrical pattern
+responsible for creating the classical macroscopic N-S field of the magnet.",1911.05735v1
+2000-02-23,ISO spectroscopy of circumstellar dust in the Herbig Ae systems AB Aur and HD 163296,"Using both the Short- and Long-wavelength Spectrometers on board the Infrared
+Space Observatory (ISO), we have obtained infrared spectra of the Herbig Ae
+systems AB Aur and HD 163296. In addition, we obtained ground-based N band
+images of HD 163296. Our results can be summarized as follows: (1) The main
+dust components in AB Aur are amorphous silicates, iron oxide and PAHs; (2) The
+circumstellar dust in HD 163296 consists of amorphous silicates, iron oxide,
+water ice and a small fraction of crystalline silicates; (3) The infrared
+fluxes of HD 163296 are dominated by solid state features; (4) The colour
+temperature of the underlying continuum is much cooler in HD 163296 than in AB
+Aur, pointing to the existence of a population of very large (mm sized) dust
+grains in HD 163296; (5) The composition and degree of crystallization of
+circumstellar dust are poorly correlated with the age of the central star. The
+processes of crystallization and grain growth are also not necessarily coupled.
+This means that either the evolution of circumstellar dust in protoplanetary
+disks happens very rapidly (within a few Myr), or that this evolution is
+governed by factors other than stellar mass and age.",0002440v1
+2004-08-09,Solar System Formation Deduced from Observations of Matter,"Aspects of our Solar System's formation are deduced from observations of the
+chemical nature of matter. Massive cores are indicative of
+terrestrial-planet-composition-similarity to enstatite chondrite meteorites,
+whose highly-reduced state of oxidation may be thermodynamically stable in
+solar matter only at elevated temperatures and pressures. Consistent with the
+formation of Earth as envisioned by Arnold Eucken, thermodynamic considerations
+lead to the deduction that the terrestrial planets formed by
+liquid-condensation, raining out from the central regions of hot, gaseous
+protoplanets. The mass of protoplanetary-Earth, estimated to be 275-305mE, is
+similar to the mass of Jupiter, 318mE. Solar primordial gases and volatile
+elements were separated from the terrestrial planets early after planet
+formation, presumably during some super-luminous solar event, perhaps even
+before Mercury had completely formed. The
+pre-super-luminosity-terrestrial-planet mass distribution appears to be more
+consistent with observations of the close-in gas-giants of other planetary
+systems than the present-day-terrestrial-planet mass distribution. Although
+primarily formed by raining out from the centers of hot, gaseous protoplanets,
+evidence for the Earth and, by inference for the other terrestrial planets,
+suggests some outer, minor, secondary accretion of oxidized matter in the
+grain-growth accumulation way envisioned by George W. Wetherill. By contrast,
+the so-called ""standard model"" for our Solar System's formation has flawed
+conceptual underpinnings and would lead to the contradiction of terrestrial
+planets having insufficiently massive cores.",0408151v1
+2004-10-01,Mercury's Protoplanetary Mass,"Major element fractionation among chondrites has been discussed for decades
+as ratios relative to Si or Mg. Recently, by expressing ratios relative to Fe,
+I discovered a new relationship admitting the possibility that ordinary
+chondrite meteorites are derived from two components, a relatively oxidized and
+undifferentiated, primitive component and a somewhat differentiated, planetary
+component, with oxidation state like the highly reduced enstatite chondrites,
+which I suggested was identical to Mercury's complement of lost elements. Here,
+on the basis of that relationship, I derive expressions, as a function of the
+mass of planet Mercury and the mass of its core, to estimate the mass of
+Mercury's lost elements, the mass of Mercury's alloy and rock protoplanetary
+core, and the mass of Mercury's gaseous protoplanet. Although Mercury's mass is
+well known, its core mass is not, being widely believed to be in the range of
+70-80 percent of the planet mass. For a core mass of 75 percent, the mass of
+Mercury's lost elements is about 1.32 times the mass of Mercury, the mass of
+the alloy and rock protoplanetary core is about 2.32 times the mass of Mercury,
+and the mass of the gaseous protoplanet of Mercury is about 700 times the mass
+of Mercury. Circumstantial evidence is presented in support of the supposition
+that Mercury's lost elements is identical to the planetary component of
+ordinary chondrite formation.",0410009v1
+2004-10-08,Total Mass of Ordinary Chondrite Matter Originally Present in the Solar System,"Recently, I reported the discovery of a new fundamental relationship of the
+major elements (Fe, Mg, Si) of chondrites that admits the possibility that
+ordinary chondrite meteorites are derived from two components, a relatively
+oxidized and undifferentiated, primitive component and a somewhat
+differentiated, planetary component, with oxidation state like the highly
+reduced enstatite chondrites, which I suggested was identical to Mercury's
+complement of lost elements. Subsequently, on the basis of that relationship, I
+derived expressions, as a function of the mass of planet Mercury and the mass
+of its core, to estimate the mass of Mercury's lost elements, the mass of
+Mercury's alloy and rock protoplanetary core, and the mass of Mercury's gaseous
+protoplanet. Here, on the basis of the supposition that Mercury's complement of
+lost elements is in fact identical to the planetary component of ordinary
+chondrite formation, I estimate, as a function of Mercury's core mass, the
+total mass of ordinary chondrite matter originally present in the Solar System.
+Although Mercury's mass is well known, its core mass is not, being widely
+believed to be in the range of 70 to 80 percent of the planet mass. For a core
+mass of 75 percent, the calculated total mass of ordinary chondrite matter
+originally present in the Solar System amounts to 1.83E24 kg, about 5.5 times
+the mass of Mercury. That amount of mass is insufficient in itself to form a
+planet as massive as the Earth, but may have contributed significantly to the
+formation of Mars, as well as adding to the veneer of other planets, including
+the Earth. Presently, only about 0.1 percent of that mass remains in the
+asteroid belt.",0410242v1
+2007-02-23,Biomarker Response to Galactic Cosmic Ray-Induced NOx and the Methane Greenhouse Effect in the Atmosphere of an Earthlike Planet Orbiting an M-Dwarf Star,"Planets orbiting in the habitable zone (HZ) of M-Dwarf stars are subject to
+high levels of galactic cosmic rays (GCRs) which produce nitrogen oxides in
+earthlike atmospheres. We investigate to what extent this NOx may modify
+biomarker compounds such as ozone (O3) and nitrous oxide (N2O), as well as
+related compounds such as water (H2O) (essential for life) and methane (CH4)
+(which has both abiotic and biotic sources) . Our model results suggest that
+such signals are robust, changing in the M-star world atmospheric column by up
+to 20% due to the GCR NOx effects compared to an M-star run without GCR effects
+and can therefore survive at least the effects of galactic cosmic rays. We have
+not however investigated stellar cosmic rays here. CH4 levels are about 10
+times higher than on the Earth related to a lowering in hydroxyl (OH) in
+response to changes in UV. The increase is less than reported in previous
+studies. This difference arose partly because we used different biogenic input.
+For example, we employed 23% lower CH4 fluxes compared to those studies. Unlike
+on the Earth, relatively modest changes in these fluxes can lead to larger
+changes in the concentrations of biomarker and related species on the M-star
+world. We calculate a CH4 greenhouse heating effect of up to 4K. O3
+photochemistry in terms of the smog mechanism and the catalytic loss cycles on
+the M-star world differs considerably compared with the Earth.",0702622v1
+1999-03-11,Ordering and Fluctuation of Orbital and Lattice Distortion in Perovskite Manganese Oxides,"Roles of orbital and lattice degrees of freedom in strongly correlated
+systems are investigated to understand electronic properties of perovskite Mn
+oxides such as La_{1-x}Sr_{x}MnO_{3}. An extended double-exchange model
+containing Coulomb interaction, doubly degenerate orbitals and Jahn-Teller
+coupling is derived under full polarization of spins with two-dimensional
+anisotropy. Quantum fluctuation effects of Coulomb interaction and orbital
+degrees of freedom are investigated by using the quantum Monte Carlo method. In
+undoped states, it is crucial to consider both the Coulomb interaction and the
+Jahn-Teller coupling in reproducing characteristic hierarchy of energy scales
+among charge, orbital-lattice and spin degrees of freedom in experiments. Our
+numerical results quantitatively reproduce the charge gap amplitude as well as
+the stabilization energy and the amplitude of the cooperative Jahn-Teller
+distortion in undoped compounds. Upon doping of carriers, in the absence of the
+Jahn-Teller distortion, critical enhancement of both charge compressibility and
+orbital correlation length is found with decreasing doping concentration. These
+are discussed as origins of strong incoherence in charge dynamics. With the
+Jahn-Teller coupling in the doped region, collapse of the Jahn-Teller
+distortion and instability to phase separation are obtained and favorably
+compared with experiments. These provide a possible way to understand the
+complicated properties of lightly doped manganites.",9903183v2
+2000-02-17,Adsorbed and Grafted Polymers at Equilibrium,"This chapter deals with various aspects related to the adsorption of long
+chain-like macromolecules (polymers) onto solid surfaces. Physical aspects of
+the adsorption mechanism are elaborated mainly at thermodynamical equilibrium.
+The basic features needed in modeling of this adsorption are discussed. We
+first discuss the adsorption of a single and long polymer chain to the surface.
+The surface interaction is modeled by a potential well with a long-ranged
+attractive tail. A simple mean-field theory description is presented and the
+concept of polymer ""blobs"" is used to describe the conformation of the chain at
+the surface. The thickness of the adsorbed layer depends on several polymer and
+surface parameters. Fluctuation corrections to mean-field theory are also
+discussed. We then review adsorption as well as depletion processes in the
+many-chain case. Profiles, changes in the surface tension and polymer surface
+excess are calculated within mean-field theory. Corrections due to fluctuations
+in good solvent are taken into account using scaling concepts. The proximal
+exponent is introduced in analogy to surface critical phenomena. The
+interaction between two surfaces with adsorbed polymer layers is discussed, and
+various cases leading to attractive and repulsive interactions are mentioned.
+Polyelectrolytes are of practical importance due to their water solubility; we
+give a short summary of recent progress in this rapidly evolving field. The
+behavior of grafted polymers, i.e., polymers which are anchored with one end to
+a solid substrate is also reviewed.",0002266v1
+2000-10-05,The Structure and a Bond-Valence-Sum Study of the 1-2-3 Superconductors CLBLCO and YBCO,"We present a study of the crystal structure of the 1-2-3 superconductor
+[Ca(x)La(1-x)][Ba$(1.75-x)La(0.25+x)]Cu(3)O(y) (``CLBLCO''). Because of the
+presence of both La and Ba ions in the ``Ba'' layer, the local symmetry of
+YBa(2)Cu(3)O(y) (``YBCO'') is lost. One can no longer assume that an ``apical''
+oxygen atom always lies strictly on the line joining CuI and CuII ions, and a
+Pauling bond-valence calculation is very useful as an adjunct to the Rietveld
+refinement of the positions of the La and Ba ions. When a Rietveld analysis is
+performed allowing for the possibility that the apical oxygen atoms may be
+slightly displaced along the a or b direction, the bond valence sums for both
+La and Ba are close to the natural oxidation states of these ions.
+  We have also used the bond-valence-sum method to study the mean oxidation
+states of the CuI and CuII ions in both CLBLCO and YBCO. Our results for YBCO
+differ from some previously published results. Our main conclusion is that,
+while the method may be useful in finding the charge concentration on the CuII
+plane, it definitely does not yield the concentration of mobile holes, nor the
+concentration of superconducting charge carriers.",0010079v1
+2000-10-28,High-Resolution X-Ray Reflectivity Study of Thin Layered Pt-Electrodes for Integrated Ferroelectric Devices,"The structural interface properties of layered Pt/Ti/SiO2/Si electrodes have
+been investigated using high-resolution specular and diffuse x-ray reflectivity
+under grazing angles. Currently this multilayer system represents a
+technological standard as bottom electrodes for ferroelectric thin film
+applications. For the electronic and ferroelectric properties of integrated
+devices, the film-electrode interface is of crucial importance. We focused on
+Pt-100nm/Ti-10nm/SiO2/Si electrodes prepared under annealing conditions as
+employed in industrial processing, prior to the deposition of ferroelectric
+films. The comparison between annealed and non-annealed electrodes clearly
+revealed strong interfacial effects due to interdiffusion and oxidation of Ti,
+especially at the Pt-Ti interface. Migration of Ti into the Pt-layer results in
+a clear shift of the critical angle due to enclosure of TiO(2-x) within the
+Pt-layer. The heterogeneous distribution of TiO(2-x) suggests a diffusion
+mechanism mainly along the Pt-grain boundaries. At the SiO2 interface a
+relatively weakly oxidized, remaining Ti-layer of 20 Angstroem could be found,
+which is most probably correlated with the remaining adhesion to the substrate.",0010467v1
+2001-09-17,Catalytic CO Oxidation on Nanoscale Pt Facets: Effect of Inter-Facet CO Diffusion on Bifurcation and Fluctuation Behavior,"We present lattice-gas modeling of the steady-state behavior in CO oxidation
+on the facets of nanoscale metal clusters, with coupling via inter-facet CO
+diffusion. The model incorporates the key aspects of reaction process, such as
+rapid CO mobility within each facet, and strong nearest-neighbor repulsion
+between adsorbed O. The former justifies our use a ""hybrid"" simulation approach
+treating the CO coverage as a mean-field parameter. For an isolated facet,
+there is one bistable region where the system can exist in either a reactive
+state (with high oxygen coverage) or a (nearly CO-poisoned) inactive state.
+Diffusion between two facets is shown to induce complex multistability in the
+steady states of the system. The bifurcation diagram exhibits two regions with
+bistabilities due to the difference between adsorption properties of the
+facets. We explore the role of enhanced fluctuations in the proximity of a cusp
+bifurcation point associated with one facet in producing transitions between
+stable states on that facet, as well as their influence on fluctuations on the
+other facet. The results are expected to shed more light on the reaction
+kinetics for supported catalysts.",0109295v1
+2001-10-24,A Theory for High-$T_c$ Superconductors Considering Inhomogeneous Charge Distribution,"We propose a general theory for the critical $T_c$ and pseudogap $T^*$
+temperature dependence on the doping concentration for high-$T_c$ oxides,
+taking into account the charge inhomogeneities in the $CuO_2$ planes. The well
+measured experimental inhomogeneous charge density in a given compound is
+assumed to produce a spatial distribution of local $\rho(r)$. These differences
+in the local charge concentration is assumed to yield insulator and metallic
+regions, possibly in a stripe morphology. In the metallic region, the
+inhomogeneous charge density yields also spatial distributions of
+superconducting critical temperatures $T_c(r)$ and zero temperature gap
+$\Delta_0(r)$. For a given sample, the measured onset of vanishing gap
+temperature is identified as the pseudogap temperature, that is, $T^*$, which
+is the maximum of all $T_c(r)$. Below $T^*$, due to the distribution of
+$T_c(r)$'s, there are some superconducting regions surrounded by insulator or
+metallic medium. The transition to a superconducting state corresponds to the
+percolation threshold among the superconducting regions with different
+$T_c(r)$'s. To model the charge inhomogeneities we use a double branched
+Poisson-Gaussian distribution. To make definite calculations and compare with
+the experimental results, we derive phase diagrams for the BSCO, LSCO and YBCO
+families, with a mean field theory for superconductivity using an extended
+Hubbard Hamiltonian. We show also that this novel approach provides new
+insights on several experimental features of high-$T_c$ oxides.",0110519v3
+2001-12-05,The LDA+DMFT Approach to Materials with Strong Electronic Correlations,"LDA+DMFT is a novel computational technique for ab initio investigations of
+real materials with strongly correlated electrons, such as transition metals
+and their oxides. It combines the strength of conventional band structure
+theory in the local density approximation (LDA) with a modern many-body
+approach, the dynamical mean-field theory (DMFT). In the last few years
+LDA+DMFT has proved to be a powerful tool for the realistic modeling of
+strongly correlated electronic systems. In this paper the basic ideas and the
+set-up of the LDA+DMFT(X) approach, where X is the method used to solve the
+DMFT equations, are discussed. Results obtained with X=QMC (quantum Monte
+Carlo) and X=NCA (non-crossing approximation) are presented and compared. By
+means of the model system La$_{1-x}$Sr$_{x}$TiO$_{3}$ we show that the method X
+matters qualitatively and quantitatively. Furthermore, we discuss recent
+results on the Mott-Hubbard metal-insulator transition in the transition metal
+oxide V$_2$O$_3$ and the $\alpha$-$\gamma$ transition in the 4f-electron system
+Ce.",0112079v1
+2002-08-30,On the Structural and Optical Properties of Sputtered Hydrogenated Amorphous Silicon Thin Films,"The present work is essentially focused on the study of optical and
+structural properties of hydrogenated amorphous silicon thin films (a-Si:H)
+prepared by radio-frequency cathodic sputtering. We examine separately the
+influence of hydrogen partial pressure during film deposition, and the effect
+of post-deposition thermal annealings on the main optical characteristics of
+the layers such as refraction index, optical gap and Urbach energy. Using the
+grazing X-rays reflectometry technique, thin film structural properties are
+examined immediately after films deposition as well as after surface oxidation
+or annealing. We show that low hydrogen pressures allow a saturation of
+dangling bonds in the layers, while high doses lead to the creation of new
+defects. We show also that thermal annealing under moderate temperatures
+improves the structural quality of the deposited layers. For the films examined
+just after deposition, the role of hydrogen appears in the increase of their
+density. For those analysed after a short stay in the ambient, hydrogen plays a
+protective role against the oxidation of their surfaces. This role disappears
+for a long time stay in the ambient.
+  Keywords
+  Amorphous silicon, Grazing incidence X-rays, Hydrogen, Optical properties,
+Penetration depth, Reflectometry, Thermal annealing, Thin films.
+  PACS Numbers
+  61.10.K - 61.43.D - 68.55.JK - 68.55.81.15.A",0208601v1
+2003-01-08,The problem of a metal impurity in an oxide: ab-initio study of electronic and structural properties of Cd in Rutile TiO2,"In this work we undertake the problem of a transition metal impurity in an
+oxide. We present an ab-initio study of the relaxations introduced in TiO2 when
+a Cd impurity replaces substitutionally a Ti atom. Using the Full-Potential
+Linearized-Augmented-Plane-Wave method we obtain relaxed structures for
+different charge states of the impurity and computed the electric-field
+gradients (EFGs) at the Cd site. We find that EFGs, and also relaxations, are
+dependent on the charge state of the impurity. This dependence is very
+remarkable in the case of the EFG and is explained analyzing the electronic
+structure of the studied system. We predict fairly anisotropic relaxations for
+the nearest oxygen neighbors of the Cd impurity. The experimental confirmation
+of this prediction and a brief report of these calculations have recently been
+presented [P.R.L. 89, 55503 (2002)]. Our results for relaxations and EFGs are
+in clear contradiction with previous studies of this system that assumed
+isotropic relaxations and point out that no simple model is viable to describe
+relaxations and the EFG at Cd in TiO2 even approximately.",0301099v2
+2003-08-04,Normal-state conductivity in underdoped La_{2-x}Sr_xCuO_4 thin films: Search for nonlinear effects related to collective stripe motion,"We report a detailed study of the electric-field dependence of the
+normal-state conductivity in La_{2-x}Sr_xCuO_4 thin films for two
+concentrations of doped holes, x=0.01 and 0.06, where formation of diagonal and
+vertical charged stripes was recently suggested. In order to elucidate whether
+high electric fields are capable of depinning the charged stripes and inducing
+their collective motion, we have measured current-voltage characteristics for
+various orientations of the electric field with respect to the crystallographic
+axes. However, even for the highest possible fields (~1000 V/cm for x=0.01 and
+\~300 V/cm for x=0.06) we observed no non-linear-conductivity features except
+for those related to the conventional Joule heating of the films. Our analysis
+indicates that Joule heating, rather than collective electron motion, may also
+be responsible for the non-linear conductivity observed in some other 2D
+transition-metal oxides as well. We discuss that a possible reason why moderate
+electric fields fail to induce a collective stripe motion in layered oxides is
+that fairly flexible and compressible charged stripes can adjust themselves to
+the crystal lattice and individual impurities, which makes their pinning much
+stronger than in the case of conventional rigid charge-density waves.",0308045v1
+2004-03-01,"Non-ionic contributions to the electric-field gradient at $^{181}$Ta and $^{111}$Cd impurity sites in R$_2$O$_3$ (R= Sc, In, Lu, Yb, Tm, Er, Y, Ho, Dy, Gd, Eu, Sm) bixbyites","The time-differential perturbed-angular-correlation (TDPAC) technique was
+applied to the study of the internal electric-field gradient (EFG) in Eu- and
+Ho-sesquioxides in their cubic bixbyite phases. The results, as well as
+previous characterizations of the EFG at $^{181}$Ta sites in oxides with the
+bixbyite structure, were compared to those obtained in experiments using
+$^{111}$Cd as probe, and to point-charge model and {\it ab initio} results
+calculations for the EFG tensor at impurity sites in binary oxides. These
+studies provide quantitative information about electronic processes and the
+structural relaxations induced by the presence of impurity probes in the host
+lattices, and confirm the existence of nonionic contributions to the EFG in
+these systems. Our FP-LAPW calculations show that this nonionic contribution to
+the EFG is the dominating one, and that it is originated in the population of
+{\it p} states (5{\it p} in the case of Cd, 6{\it p} for Ta).",0403060v2
+2004-03-22,"New apparatus for DTA at 2000 bar: thermodynamic studies on Au, Ag, Al and HTSC oxides","A new DTA (Differential Thermal Analysis) device was designed and installed
+in a Hot Isostatic Pressure (HIP) furnace in order to perform high-pressure
+thermodynamic investigations up to 2 kbar and 1200C. Thermal analysis can be
+carried out in inert or oxidising atmosphere up to p(O2) = 400 bar. The
+calibration of the DTA apparatus under pressure was successfully performed
+using the melting temperature (Tm) of pure metals (Au, Ag and Al) as standard
+calibration references. The thermal properties of these metals have been
+studied under pressure. The values of DV (volume variation between liquid and
+solid at Tm), ROsm (density of the solid at Tm) and ALPHAm (linear thermal
+expansion coefficient at Tm) have been extracted. A very good agreement was
+found with the existing literature and new data were added. This HP-DTA
+apparatus is very useful for studying the thermodynamics of those systems where
+one or more volatile elements are present, such as high TC superconducting
+oxides. DTA measurements have been performed on Bi,Pb(2223) tapes up to 2 kbar
+under reduced oxygen partial pressure (p(O2) = 0.07 bar). The reaction leading
+to the formation of the 2223 phase was found to occur at higher temperatures
+when applying pressure: the reaction DTA peak shifted by 49C at 2 kbar compared
+to the reaction at 1 bar. This temperature shift is due to the higher stability
+of the Pb-rich precursor phases under pressure, as the high isostatic pressure
+prevents Pb from evaporating.",0403556v1
+2004-10-04,The role of nitrogen related defects in high-k dielectric oxides: Density functional studies,"Using ab initio density functional total energy and molecular dynamics
+simulations, we study the effects of various forms of nitrogen post deposition
+anneal (PDA) on the electric properties of hafnia in the context of its
+application as a gate dielectric in field effect transistors (FET). We consider
+the atomic structure and energetics of nitrogen containing defects which can be
+formed during the PDA in various N-based ambients: N2, N+2, N, NH3, NO, N2O. We
+analyse the role of such defects in fixed charge accumulation, electron
+trapping and in the growth of the interface SiOx layer. We find that nitrogen
+anneal of the oxides leads to an effective immobilization of native defects
+such as oxygen vacancies and interstitial oxygen ions, which may inhibit growth
+of silica layer. Nitrogen in any form effectively incorporates into the
+pre-existing oxygen vacancies and, therefore may decrease the concentration of
+shallow electron traps. However, nitrogen in any form is unlikely to
+significantly reduce the fixed charge in the dielectric.",0410088v1
+2005-03-30,Phonon Knudsen flow in nanostructured semiconductor systems,"We determine the size effect on the lattice thermal conductivity of nanoscale
+wire and multilayer structures formed in and by some typical semiconductor
+materials, using the Boltzmann transport equation and focusing on the Knudsen
+flow effect. For both types of nanostructured systems we find that the phonon
+transport is reduced significantly below the bulk value by boundary scattering
+off interface defects and/or interface modes. The Knudsen flow effects are
+important for almost all types of semiconductor nanostructures but we find them
+most pronounced in Si and SiC systems due to the very large phonon mean-free
+paths. We apply and test our wire thermal-transport results to recent
+measurements on Si nanowires. We further investigate and predict size effects
+in typical multilayered SiC nanostructures, for example, a
+doped-SiC/SiC/SiO$_2$ layered structure that could define the transport channel
+in a nanosize transistor. Here the phonon-interface scattering produces a
+heterostructure thermal conductivity smaller than what is predicted in a
+traditional heat-transport calculation, suggesting a breakdown of the
+traditional Fourier analysis even at room temperatures. Finally, we show that
+the effective thermal transport in a SiC/SiO$_2$ heterostructure is sensitive
+to the oxide depth and could thus be used as an in-situ probe of the SiC
+oxidation progress.",0503701v1
+2005-04-20,Covalent bonding and hybridization effects in the corundum-type transition-metal oxides V2O3 and Ti2O3,"The electronic structure of the corundum-type transition-metal oxides V2O3
+and Ti2O3 is studied by means of the augmented spherical wave method, based on
+density-functional theory and the local density approximation. Comparing the
+results for the vanadate and the titanate allows us to understand the peculiar
+shape of the metal 3d a_{1g} density of states, which is present in both
+compounds. The a_{1g} states are subject to pronounced bonding-antibonding
+splitting due to metal-metal overlap along the c-axis of the corundum
+structure. However, the corresponding partial density of states is strongly
+asymmetric with considerably more weight on the high energy branch. We argue
+that this asymmetry is due to an unexpected broadening of the bonding a_{1g}
+states, which is caused by hybridization with the e_g^{pi} bands. In contrast,
+the antibonding a_{1g} states display no such hybridization and form a sharp
+peak. Our results shed new light on the role of the a_{1g} orbitals for the
+metal-insulator transitions of V2O3. In particular, due to a_{1g} - e_g^{pi}
+hybridization, an interpretation in terms of molecular orbital singlet states
+on the metal-metal pairs along the c-axis is not an adequate description.",0504524v1
+2005-05-19,Strongly correlated properties of the thermoelectric cobalt oxide Ca3Co4O9,"We have performed both in-plane resistivity, Hall effect and specific heat
+measurements on the thermoelectric cobalt oxide Ca$_{3}$Co$_{4}$O$_{9}$. Four
+distinct transport regimes are found as a function of temperature,
+corresponding to a low temperature insulating one up to $T_{min}\approx $63 K,
+a strongly correlated Fermi liquid up to $T^*\approx $140 K, with
+$\rho=\rho_0+AT^2$ and $A\approx 3.63$ $10^{-2} \mu \Omega cm/K^{2}$, followed
+by an incoherent metal with $k_Fl\leq 1$ and a high temperature insulator above
+T$^{**}\approx $510 K . Specific heat Sommerfeld coefficient $\gamma = 93$
+mJ/(mol.K$^{2}$) confirms a rather large value of the electronic effective mass
+and fulfils the Kadowaki-Woods ratio $A/\gamma^2 \approx 0.45$ 10$^{-5}$ $\mu
+\Omega cm.K^2/(mJ^2mol^{-2})$. Resistivity measurements under pressure reveal a
+decrease of the Fermi liquid transport coefficient A with an increase of $T^*$
+as a function of pressure while the product $A(T^*)^2/a$ remains constant and
+of order $h/e^2$. Both thermodynamic and transport properties suggest a strong
+renormalization of the quasiparticles coherence scale of order $T^*$ that seems
+to govern also thermopower.",0505464v1
+2005-05-30,"Bose-Einstein Condensation Picture of Superconductivity in Ag2 (Ag3Pb2H2O6), Na0.05WO3 and Na0.041NH3 composites. (Dilute metals)","Traditionally, when one describes the crystallographic structure of oxides,
+the oxygen ion radius r02 is assumed to be approximately equal to 1.4A. The
+oxygen ions occupy in this case 80-90% of the crystal volume. Metal atoms are
+considered then as ions playing a role of donors with rather small radius of
+(0.5 - 0.8) A. However, the atomic packing picture and, therefore, physical
+properties such as electric conductivity and superconductivity of oxides will
+be essentially different, if we assume r02- ~ 0.56 A. Such magnitude of the
+radius is known from the quantum mechanics calculations [2]. According to this
+picture, 80-90 % of the crystal volume is occupied by the metal atom orbitals
+with radius (1.3-1.9) A, while the oxygen ions play a role of acceptors, which
+reduce occupancy of these orbitals (""indirect"" dilution of the metal). A
+""direct"" dilution of metals takes place in stoichiometric matrices. When
+r02-~0.56 A, channels with diameter 3.6 A present in the hexagonal matrix
+Ag3Pb2H2O6 directed along the ""c"" axis.
+  The channels are filled by chains of the Ag2 molecules with atomic diameter
+of 2.6 A and the molecule concentration n_B = 25.6 10^20 cm^-3.
+  The Bose-Einstein condensation (BEC) temperature T_cB ~ 400K is calculated
+for the electron effective mass value m*=7.5m_e, where m_e is the isolated
+electron mass. Three-dimensional networks of Na2 chains form in Na solutions in
+NH3 and WO3 as well (respectively, with n_B=4.71 10^20 cm^-3;
+  T_c sim 180K; m*=5.0m_e and n_B=4.74 10^20 cm^-3; T_c sim 91K; m*=10m_e).
+Close magnitudes of the Ag2 and Na2 chains parameters respectively in NH3 and
+WO3 favors the opinion that all these structures have a composite structure and
+similar mechanisms of the high temperature superconductivity.",0505718v1
+2005-06-01,Insulator-metal transition in a conservative system: An evidence for mobility coalescence in island silver films,"Aging, which manifests itself as an irreversible increase in electrical
+resistance in island metal films is of considerable interest from both academic
+as well as applications point of view. Aging is attributed to various causes,
+oxidation of islands and mobility of islands followed by coalescence (mobility
+coalescence) being the main contenders. The effect of parameters like substrate
+temperature, substrate cleaning, residual gases in the vacuum chamber,
+ultrasonic vibration of the substrate, suggest that the mobility coalescence is
+responsible for the aging in island metal films. Electron microscopy studies
+show evidence for mobility of islands at high substrate temperatures. The
+comparison of aging data of island silver films deposited on glass substrates
+in ultra high vacuum and high vacuum suggests that the oxidation of islands, as
+being responsible for aging in these films, can be ruled out. Further, under
+certain conditions of deposition, island silver films exhibit a dramatic and
+drastic fall in electrical resistance, marking the insulator-metal transition.
+This interesting transition observed in a conservative system - after the
+stoppage of deposition of the film- is a clear evidence for mobility
+coalescence of islands even at room temperature. The sudden fall in resistance
+is preceded by fluctuations in resistance with time and fluctuations are
+attributed to the making and breaking of the percolation path in the film.",0506022v2
+2005-06-13,"Decay of Metastable Nonequilibrium Phases, Enhanced Reaction Rate, and Dynamic Phase Transition in a Model of CO Oxidation with CO Desorption","We present a computational study of the dynamic behavior of a
+Ziff-Gulari-Barshad model of CO oxidation with CO desorption on a catalytic
+surface. Our results provide further evidence that below a critical desorption
+rate the model exhibits a non-equilibrium, first-order phase transition between
+low and high CO coverage phases. Our kinetic Monte Carlo simulations indicate
+that the transition process between these phases follows a decay mechanism very
+similar to the one described by the classic Kolmogorov-Johnson-Mehl-Avrami
+theory of phase transformation by nucleation and growth. We measure the
+lifetimes of the metastable phases on each side of the transition line and find
+that they are strongly dependent on the direction of the transformation, i.e.,
+from low to high coverage or vice versa. Inspired by this asymmetry, we
+introduce a square-wave periodic external forcing, whose two parameters can be
+tuned to enhance the catalytic activity. At CO desorption rates below the
+critical value, we find that this far-from-equilibrium system undergoes a
+dynamic phase transition between a CO_2 productive phase and a nonproductive
+one. In the space of the parameters of the periodic external forcing, this
+nonequilibrium phase transition defines a line of critical points. The maximum
+enhancement rate for the CO_2 production rate occurs near this critical line.",0506271v1
+2005-10-03,A Study of Apparent Symmetry Breakdown in Perovskite Oxide-based Symmetric RRAM Devices,"A new model of a symmetric two-terminal non-volatile RRAM device based on
+Perovskite oxide thin film materials, specifically Pr1-xCaxMnO3 (PCMO), is
+proposed and analyzed. The model consists of two identical half-parts, which
+are completely characterized by the same resistance verses pulse voltage
+hysteresis loop, connected together in series. Even though the modeled device
+is physically symmetric with respect to the direction of current, it is found
+to exhibit switching of the resistance with the application of voltage pulses
+of sufficient amplitude and of different polarities. The apparent breakdown of
+parity conservation of the device is attributed to changes in resistance of the
+active material layer near the electrodes during switching. Thus the switching
+is history dependent, a feature that can be very useful for the construction of
+real non-volatile memory devices. An actual symmetric device, not previously
+reported in the literature and based on the proposed model, is fabricated in
+the PCMO material system. Measurements of the resistance of this new device
+generated an experimental hysteresis curve that matches well the calculated
+hysteresis curve of the model, thus confirming the features predicated by the
+new symmetric model.",0510059v1
+2005-10-17,Nodal quasiparticle in pseudogapped colossal magnetoresistive manganites,"A characteristic feature of the copper oxide high-temperature superconductors
+is the dichotomy between the electronic excitations along the nodal (diagonal)
+and antinodal (parallel to the Cu-O bonds) directions in momentum space,
+generally assumed to be linked to the ""d-wave"" symmetry of the superconducting
+state. Angle-resolved photoemission measurements in the superconducting state
+have revealed a quasiparticle spectrum with a d-wave gap structure that
+exhibits a maximum along the antinodal direction and vanishes along the nodal
+direction. Subsequent measurements have shown that, at low doping levels, this
+gap structure persists even in the high-temperature metallic state, although
+the nodal points of the superconducting state spread out in finite ""Fermi
+arcs"". This is the so-called pseudogap phase, and it has been assumed that it
+is closely linked to the superconducting state, either by assigning it to
+fluctuating superconductivity or by invoking orders which are natural
+competitors of d-wave superconductors. Here we report experimental evidence
+that a very similar pseudogap state with a nodal-antinodal dichotomous
+character exists in a system that is markedly different from a superconductor:
+the ferromagnetic metallic groundstate of the colossal magnetoresistive bilayer
+manganite La1.2Sr1.8Mn2O7. Our findings therefore cast doubt on the assumption
+that the pseudogap state in the copper oxides and the nodal-antinodal dichotomy
+are hallmarks of the superconductivity state.",0510423v1
+2005-11-11,Electronic Structure Calculations using Dynamical Mean Field Theory,"The calculation of electronic properties of materials is an important task of
+solid state theory, albeit particularly difficult if electronic correlations
+are strong, for example in transition metals, their oxides and in f-electron
+systems. The standard approach to material calculations, the density functional
+theory in its local density approximation (LDA), incorporates electronic
+correlations only very rudimentarily and fails if the correlations are strong.
+Encouraged by the success of dynamical mean field theory (DMFT) in dealing with
+strongly correlated model Hamiltonians, physicists from the bandstructure and
+the many-body community have joined forces and developed a combined LDA+DMFT
+method recently. Depending on the strength of electronic correlations, this new
+approach yields a weakly correlated metal as in LDA, a strongly correlated
+metal, or a Mott insulator. By now, this approach is widely regarded as a
+breakthrough for electronic structure calculations of strongly correlated
+materials.
+  The author will review this LDA+DMFT method and also discuss alternative
+approaches to employ DMFT in electronic structure calculations, for example, by
+replacing the LDA part by the so-called GW approximation. Different methods to
+solve the DMFT equations are introduced with a focus on those that are suitable
+for realistic calculations with many orbitals. An overview of the successful
+application of LDA+DMFT to a wide variety of materials, ranging from Pu and Ce,
+to Fe and Ni, to numerous transition metal oxides, is given.",0511293v2
+2006-03-03,Study of Correlation Effects in the High Formal Oxidation State Compound Sr$_2$CoO$_4$,"Two recent reports confirm that the newly synthesized Sr$_2$CoO$_4$ (formal
+oxidation state Co$^{4+}$) shows a high Curie temperature (~ 250 K), but they
+report different moments of 1.8 $\mu_B$ and 1 $\mu_B$ per Co. Using both
+commonly used functionals in the correlated band approach (LDA+U) as well as
+the local density approximation (LDA),the combined effects of correlation and
+hybridization with O 2p states are calculated and analyzed. Sr$_2$CoO$_2$ is
+already ferromagnetic within LDA (M=1.95 $\mu_B$). Increasing U from zero, the
+two LDA+U schemes affect the moment oppositely out to a critical value
+$U_c$=2.5 eV, at which point they transform discontinuously from different
+states to the same large U state. Fixing U at $U_c$, fixed spin moment
+calculations show similar behavior out to a minimum at 1$\mu_B$ (a half
+metallic state), beyond which the fully-localized-limit scheme jumps to a state
+with energy minimum very near 2$\mu_B$ very close to the LDA moment). Although
+the energy minima occur very near integer values of the moment/Co (1$\mu_B,
+2$\mu_B$), the strong 3d-2p mixing and resulting 3d orbital occupations seem to
+preclude any meaningful S=1/2 or S=1 assignment to the Co ion.",0603075v1
+2006-03-04,Electronically coupled complementary interfaces between perovskite band insulators,"Perovskite oxides exhibit a plethora of exceptional electronic properties,
+providing the basis for novel concepts of oxide-electronic devices. The
+interest in these materials is even extended by the remarkable characteristics
+of their interfaces. Studies on single epitaxial connections between the two
+wide-bandgap insulators LaAlO3 and SrTiO3 have revealed them to be either
+high-mobility electron conductors or insulating, depending on the atomic
+stacking sequences. In the latter case they are conceivably positively charged.
+For device applications, as well as for basic understanding of the interface
+conduction mechanism, it is important to investigate the electronic coupling of
+closely-spaced complementary interfaces. Here we report the successful
+realization of such electronically coupled complementary interfaces in SrTiO3 -
+LaAlO3 thin film multilayer structures, in which the atomic stacking sequence
+at the interfaces was confirmed by quantitative transmission electron
+microscopy. We found a critical separation distance of 6 perovskite unit cell
+layers, corresponding to approximately 2.3 nm, below which a decrease of the
+interface conductivity and carrier density occurs. Interestingly, the high
+carrier mobilities characterizing the separate electron doped interfaces are
+found to be maintained in coupled structures down to sub-nanometer interface
+spacing.",0603088v1
+2006-04-21,"Metastable phases and ""metastable"" phase diagrams","The work discusses specifics of phase transitions for metastable states of
+substances. The objects of condensed media physics are primarily equilibrium
+states of substances with metastable phases viewed as an exception, while the
+overwhelming majority of organic substances investigated in chemistry are
+metastable. It turns out that at normal pressure many of simple molecular
+compounds based on light elements (these include: most hydrocarbons; nitrogen
+oxides, hydrates, and carbides; carbon oxide (CO); alcohols, glycerin etc) are
+metastable substances too, i.e. they do not match the Gibbs' free energy
+minimum for a given chemical composition. At moderate temperatures and
+pressures, the phase transitions for given metastable phases throughout the
+entire experimentally accessible time range are reversible with the equilibrium
+thermodynamics laws obeyed. At sufficiently high pressures (1-10 GPa), most of
+molecular phases irreversibly transform to more energy efficient polymerized
+phases, both stable and metastable. These transformations are not consistent
+with the equality of the Gibbs' free energies between the phases before and
+after the transition, i.e. they are not phase transitions in ""classical""
+meaning. The resulting polymeric phases at normal pressure can exist at
+temperatures above the melting one for the initial metastable molecular phase.
+Striking examples of such polymers are polyethylene and a polymerized
+modification of CO. Many of energy-intermediate polymeric phases can apparently
+be synthesized by the ""classical"" chemistry techniques at normal pressure.",0604512v1
+2006-11-19,Ferroelectric switched all-metallic-oxide $p$-$n$ junctions,"We report the first formation of the metallic $p$-$n$ junctions, the
+ferroelectric (Ba,Sr)TiO$_3$ (BST) switched optimally electron-doped ($n$-type)
+metallic T'-phase superconductor, (La,Ce)$_2$CuO$_4$ (LCCO), and hole-doped
+($p$-type) metallic CMR manganite (La,Sr)MnO$_3$ (LSMO) junctions. In contrast
+with the previous semiconductor $p$-$n$ ($p$-$I$-$n$) junctions which are
+switched by the built-in field $V_0$, the present metallic oxides $p$-$I$-$n$
+junctions are switched by double barrier fields, the built-in field $V_0$, and
+the ferroelectric reversed polarized field $V_{rp}$, both take together to lead
+the junctions to possess definite parameters, such as definite negligible
+reversed current ($10^{-9}$ A), large breakdown voltage ($>$7 V), and ultrahigh
+rectification ($>2\times10^4$) in the bias voltage 1.2 V to 2.0 V and
+temperature range from 5 to over 300 K. The related transport feature, barrier
+size effect, and temperature effect are also observed and defined.",0611501v1
+2007-01-05,Origin and roles of a strong electron-phonon interaction in cuprate oxide superconductors,"A strong electron-phonon interaction arises from the modulation of the
+superexchange interaction by lattice vibrations. It is responsible for the
+softening of the half-breathing modes around (pm pi/a,0) and (0, pm pi/a) in
+the two-dimensional Brillouin zone, with a being the lattice constant of CuO_2
+planes, as is studied in Phys. Rev. B70, 184514 (2004). Provided that
+antiferromagnetic spin fluctuations are developed around Q=(pm 3 pi/4a, pm
+pi/a) and (pm pi/a, pm 3 pi/4a), the electron-phonon interaction can also cause
+the softening of Cu-O bond stretching modes around 2Q, or around (pm pi/2a,0)
+and (0, pm pi/2a). The softening around 2Q is accompanied by the development of
+charge fluctuations corresponding to the so called 4a-period stripe or
+4a*4a-period checker-board state. However, an observation that the 4a-period
+modulating part or the 2Q part of the density of states is almost symmetric
+with respect to the chemical potential contradicts a scenario that the
+stabilization of a single-2Q or double-2Q charge density wave following the
+complete softening of the 2Q bond stretching modes is responsible for the
+ordered stripe or checker-board state. It is proposed that the stripe or
+checker-board state is simply a single-Q or double-Q spin density wave, whose
+second-harmonic effects can explain the observed almost symmetric 2Q part of
+the density of states. The strong electron-phonon interaction can play no or
+only a minor role in the occurrence of d gamma-wave superconductivity in
+cuprate oxides.",0701088v1
+2007-01-17,Superlight small bipolarons: a route to room temperature superconductivity,"Extending the BCS theory towards the strong electron-phonon interaction
+(EPI), a charged Bose liquid of small bipolarons has been predicted by us with
+a further prediction that the highest superconducting critical temperature is
+found in the crossover region of the EPI strength from the BCS-like to
+bipolaronic superconductivity. Later on we have shown that the unscreened
+(infinite-range) Froehlich EPI combined with the strong Coulomb repulsion
+create \emph{superlight} small bipolarons, which are several orders of
+magnitude lighter than small bipolarons in the Holstein-Hubbard model (HHM)
+with a zero-range EPI. The analytical and numerical studies of this
+Coulomb-Froehlich model (CFM) provide the following recipes for
+room-temperature superconductivity: (a) The parent compound should be an ionic
+insulator with light ions to form high-frequency optical phonons, (b) The
+structure should be quasi two-dimensional to ensure poor screening of
+high-frequency phonons polarized perpendicular to the conducting planes, (c) A
+triangular lattice is required in combination with strong, on-site
+  Coulomb repulsion to form the small superlight bipolaron, (d) Moderate
+carrier densities are required to keep the system of small bipolarons close to
+the Bose-Einstein condensation regime. Clearly most of these conditions are
+already met in the cuprates.",0701412v2
+2007-01-26,Stoichiometry of Electrostatic Complexes Determined by Light Scattering,"We report on the electrostatic complexation between oppositely charged
+polymers and inorganic nanoparticles investigated by static and dynamical light
+scattering. The nanoparticles put under scrutiny were citrate-coated
+nanocrystals of cerium oxide (CeO2, nanoceria), of iron oxide (Fe2O3,
+maghemite) and of europium-doped yttrium vanadate (Eu:YVO4) with sizes in the
+10 nm range. For the polymers, we have used cationic-neutral diblock copolymers
+(poly(trimethylammonium ethylacrylate)-b-poly(acrylamide), hereafter referred
+to as PTEA-b-PAM) with different molecular weights. For the three colloidal
+dispersions, we show that the electrostatic complexation gives rise to the
+formation of stable nanoparticle clusters in the 100 nm range. The complexation
+was monitored by systematic measurements of the scattering intensity versus X,
+the mixing ratio between nanoparticles and polymers. For 5 nanoparticle/polymer
+pairs, namely CeO2/PTEA5K-b-PAM30K, Fe2O3/PTEA5K-b-PAM30K,
+Fe2O3/PTEA11K-b-PAM30K, Eu:YVO4/PTEA2K-b-PAM60K and Eu:YVO4/PTEA5K-b-PAM30K, we
+found a unique behavior : the scattering intensity exhibits a sharp and
+prominent peak in the intermediate X-range. To account for this behavior, we
+have developed a model which assumes that regardless of X, the mixed aggregates
+are formed at a fixed polymer-to-nanoparticle ratio. The agreement between the
+results and the model is excellent on the 5 systems. Results at different
+molecular weights suggest that the stoichiometry of the mixed aggregates is
+controlled by the electrostatic interactions between the opposite charges. The
+model allows to derive the molecular weight and the stoichiometry of the mixed
+aggregates.",0701662v1
+2007-03-02,A physics-based life prediction methodology for thermal barrier coating systems,"A novel mechanistic approach is proposed for the prediction of the life of
+thermal barrier coating (TBC) systems. The life prediction methodology is based
+on a criterion linked directly to the dominant failure mechanism. It relies on
+a statistical treatment of the TBC's morphological characteristics,
+non-destructive stress measurements and on a continuum mechanics framework to
+quantify the stresses that promote the nucleation and growth of microcracks
+within the TBC. The last of these accounts for the effects of TBC constituents'
+elasto-visco-plastic properties, the stiffening of the ceramic due to sintering
+and the oxidation at the interface between the thermally insulating yttria
+stabilized zirconia (YSZ) layer and the metallic bond coat. The mechanistic
+approach is used to investigate the effects on TBC life of the properties and
+morphology of the top YSZ coating, metallic low-pressure plasma sprayed bond
+coat and the thermally grown oxide. Its calibration is based on TBC damage
+inferred from non-destructive fluorescence measurements using
+piezo-spectroscopy and on the numerically predicted local TBC stresses
+responsible for the initiation of such damage. The potential applicability of
+the methodology to other types of TBC coatings and thermal loading conditions
+is also discussed.",0703069v1
+2007-03-10,Hybridized quadrupole-dipole exciton effects in $Cu_2O$ - Organic Heterostructure,"In the present work we discuss resonant hybridization of the $1S$ quadrupole
+Wannier-Mott exciton (WE) in a $Cu_2O$ quantum well with the Frenkel (FE)
+dipole exciton in an adjacent layer of organic DCM2:CA:PA. The coupling between
+excitons is due to interaction between the gradient of electric field induced
+by DCM2 Frenkel exciton and the quadrupole moment of the $1S$ transition in the
+cuprous oxide. The specific choice of the organic allows us to use the
+mechanism of 'solid state solvation' to dynamically tune the WE and FE into
+resonance during time $\approx 3.3 \: ns$ (comparable with the big life time of
+the WE) of the 'slow' phase of the solvation. The quadrupole-dipole hybrid
+utilizes the big oscillator strength of the FE along with the big lifetime of
+the quadrupole exciton, unlike dipole-dipole hybrid exciton which utilizes big
+oscillator strength of the FE and big radius of the dipole allowed WE. Due to
+strong spatial dispersion and big mass of the quadrupole WE the hybridization
+is not masked by the kinetic energy or the radiative broadening. The lower
+branch of the hybrid dispersion exhibits a pronounced minimum and may be used
+in applications. Also we investigate and report noticeable change in the
+coupling due to a induced 'Stark effect' from the strong local electric field
+of the FE. We investigated the fine energy structure of the quantum well
+confined ortho and para excitons in cuprous oxide.",0703268v1
+2003-12-16,"Exact solutions for Bianchi type cosmological metrics, Weyl orbits of E_{8(8)} subalgebras and p--branes","In this paper we pursue further a programme initiated in a previous work and
+aimed at the construction, classification and property investigation of time
+dependent solutions of supergravity (superstring backgrounds) through a
+systematic exploitation of U-duality hidden symmetries. This is done by first
+reducing to D=3 where the bosonic part of the theory becomes a sigma model on
+E_{8(8)}/SO(16), solving the equations through an algorithm that produces
+general integrals for any chosen regular subalgebra G_r of E_{8(8)} and then
+oxiding back to D=10. Different oxidations and hence different physical
+interpretations of the same solutions are associated with different embeddings
+of G_r. We show how such embeddings constitute orbits under the Weyl group and
+we study the orbit space. This is relevant to associate candidate superstring
+cosmological backgrounds to space Dp-brane configurations that admit
+microscopic descriptions. In particular in this paper we show that there is
+just one Weyl orbit of A_r subalgebras for r < 6$. The orbit of the previously
+found A_2 solutions, together with space--brane representatives contains a pure
+metric representative that corresponds to homogeneous Bianchi type 2A
+cosmologies in D=4 based on the Heisenberg algebra. As a byproduct of our
+methods we obtain new exact solutions for such cosmologies with and without
+matter. We present a thorough investigation of their properties.",0312189v1
+2006-08-23,Kac-Moody Algebras in M-theory,"In this thesis, we consider several aspects of over-extended and
+very-extended Kac-Moody algebras in relation with theories of gravity coupled
+to matter. In the first part, we focus on the occurrence of KM algebras in the
+cosmological billiards. We analyse the billiards in the simplified situation of
+spatially homogeneous cosmologies. The most generic cases lead to the same
+algebras as those met in the general inhomogeneous case, but also sub-algebras
+of the ""generic"" ones appear. Next, we consider particular gravitational
+theories which, upon toroidal compactification to D=3 space-time dimensions,
+reduce to a theory of gravity coupled to a symmetric space non-linear
+sigma-model. We show that the billiard analysis gives direct information on
+possible dimensional oxidations (or on their obstructions) and field content of
+the oxidation endpoint. We also consider all hyperbolic Kac-Moody algebras and
+completely answer the question of whether or not a specific theory exists
+admitting a billiard characterised by the given hyperbolic algebra. In the
+second part, we turn to the set up of such gravity-matter theories through the
+building of an action explicitly invariant under a Kac-Moody group. As a first
+step to include fermions, we check the compatibility of the presence of a Dirac
+fermion with the (hidden duality) symmetries appearing in the toroidal
+compactification down to 3 space-time dimensions. Next, we investigate how the
+fermions (with spin 1/2 or 3/2) fit in the conjecture for hidden over-extended
+symmetry G++. Finally, in the context of G+++ invariant actions, we derive all
+the possible signatures for all the GB++ theories that can be obtained from the
+conventional one (1,D-1) by ""dualities"" generated by Weyl reflections. This
+generalizes the results obtained for E8++.",0608161v1
+1998-08-26,Structures and Stabilities of Doubly-charged (MgO)nMg2+ (n=1-29) Cluster Ions,"Ab initio perturbed ion plus polarization calculations are reported for
+doubly-charged nonstoichiometric (MgO)nMg2+ (n=1-29) cluster ions. We consider
+a large number of isomers with full relaxations of the geometries, and add the
+correlation correction to the Hartree-Fock energies for all cluster sizes. The
+polarization contribution is included at a semiempirical level also for all
+cluster sizes. Comparison is made with theoretical results for neutral (MgO)n
+clusters and singly-charged alkali-halide cluster ions. Our method is also
+compared to phenomenological pair potential models in order to asses their
+reliability for calculations on small ionic systems. The large
+coordination-dependent polarizabilities of oxide anions favor the formation of
+surface sites, and thus bulklike structures begin to dominate only after n=24.
+The relative stabilities of the cluster ions against evaporation of a MgO
+molecule show variations that are in excellent agreement with the experimental
+abundance spectra.",9808036v2
+2005-12-06,Measuring the role of surface chemistry in silicon microphotonics,"The silicon/silicon dioxide (Si/SiO2) interface plays a crucial role in the
+performance, cost, and reliability of most modern microelectronic devices, from
+the basic transistor to flash memory, digital cameras, and solar cells. Today
+the gate oxide thickness of modern transistors is roughly 5 atomic layers, with
+8 metal wire layers required to transport all the signals within a
+microprocessor. In addition to the increasing latency of such reduced-dimension
+metal wires, further ""Moore's Law"" scaling of transistor cost and density is
+predicted to saturate in the next decade. As a result, silicon-based
+microphotonics is being explored for the routing and generation of
+high-bandwidth signals. In comparison to the extensive knowledge of the
+electronic properties of the Si/SiO2 interface, little is known about the
+optical properties of Si surfaces used in microphotonics. In this Letter, we
+explore the optical properties of the Si surface in the
+telecommunication-relevant wavelength band of 1400-1600 nm. Utilizing a high
+quality factor (Q ~ 1.5x10^6) optical microresonator to provide sensitivity
+down to a fractional surface optical loss of 10^-7, we show that optical loss
+within Si microphotonic components can be dramatically altered by Si surface
+preparation, with fraction loss of 2 x 10^-5 measured for chemical oxide
+surfaces as compared to <2 x 10^-6 for hydrogen-terminated Si surfaces. These
+results indicate that the optical properties of Si surfaces can be
+significantly and reversibly altered by standard microelectronics treatments,
+and that stable, high optical quality surface passivation layers will be
+critical in future Si micro- and nano-photonic systems.",0512040v1
+2006-04-06,Ceramic Methyltrioxorhenium,"The metal oxide polymeric methyltrioxorhenium [(CH3)xReO3] is an unique
+epresentative of a layered inherent conducting organometallic polymer which
+adopts the structural motifs of classical perovskites in two dimensions (2D) in
+form of methyl-deficient, corner-sharing ReO5(CH3) octahedra. In order to
+improve the characteristics of polymeric methyltrioxorhenium with respect to
+its physical properties and potential usage as an inherentconducting polymer we
+tried to optimise the synthetic routes of polymeric modifications of 1 to
+obtain a sintered ceramic material, denoted ceramic MTO. Ceramic MTO formed in
+a solvent-free synthesis via auto-polymerisation and subsequent sintering
+processing displays clearly different mechanical and physical properties from
+polymeric MTO synthesised in aqueous solution. Ceramic MTO is shown to display
+activated Re-C and Re=O bonds relative to MTO. These electronic and structural
+characteristics of ceramic MTO are also reflected by a different chemical
+reactivity compared with its monomeric parent compound. First examples of the
+unprecedented reactivity of ceramic MTO in the field of amine oxidations are
+shown - results which warrant further exploitation.",0604046v1
+2005-06-20,Chemical and Structural Disorder in Eumelanins - A Possible Explanation for Broad Band Absorbance,"We report the results of an experimental and theoretical study of the
+electronic and structural properties of a key eumelanin precursor -
+5,6,-dihydroxyindole-2-carboxylic acid (DHICA) and its dimeric forms. We have
+used optical spectroscopy to follow the oxidative polymerization of DHICA to
+eumelanin, and observe red shifting and broadening of the absorption spectrum
+as the reaction proceeds. First principles density functional theory
+calculations indicate that DHICA oligomers (possible reaction products of
+oxidative polymerization) have red shifted HOMO-LUMO gaps with respect to the
+monomer. Furthermore, different bonding configurations (leading to oligomers
+with different structures) produce a range of gaps. These experimental and
+theoretical results lend support to the chemical disorder model where the broad
+band monotonic absorption characteristic of all melanins is a consequence of
+the superposition of a large number of inhomogeneously broadened Gaussian
+transitions associated with each of the components of a melanin ensemble. These
+results suggest that the traditional model of eumelanin as an amorphous organic
+semiconductor is not required to explain its optical properties, and should be
+thoroughly re-examined. These results have significant implications for our
+understanding of the physics, chemistry and biological function of these
+important biological macromolecules. Indeed, one may speculate that the robust
+functionality of melanins in vitro is a direct consequence of its
+heterogeneity, i.e. chemical disorder is a ""low cost"" natural resource in these
+systems.",0506028v2
+2007-06-04,Critical Behaviour of Irreversible Reaction Systems,"An introductory review on the critical behaviour of some irreversible
+reaction systems is given. The study of these systems has attracted great
+attention during the last decades due to, on the one hand, the rich and complex
+underlying physics, and on the other hand, their relevance for numerous
+technological applications in heterogeneous catalysis, corrosion and coating,
+development of microelectronic devices, etc. The review is focuses on recent
+advances in the understanding of irreversible phase transitions (IPT's)
+providing a survey of the theoretical development of the field during the last
+decade, as well as a detailed discussion of relevant numerical simulations. The
+Langevin formulation for the treatment of second-order IPT's is discussed.
+Different Monte Carlo approaches are also presented in detail and the
+finite-size scaling analysis of second-order IPT's is described. Special
+attention is devoted to the description of recent progress in the study of
+first-order IPT's observed upon catalytic oxidation of carbon monoxide and the
+reduction of nitrogen monoxide, using lattice gas reaction models. Only brief
+comments are given on other reactions such as the oxidation of hydrogen,
+ammonia synthesis, etc. Also, a discussion of relevant experiments is presented
+and measurement are compared with the numerical results. Furthermore, promising
+areas for further research and open questions are also addressed.",0706.0419v1
+2007-07-04,Superconductivity in spinel oxide LiTi2O4 epitaxial thin films,"LiTi2O4 is a unique material in that it is the only known oxide spinel
+superconductor. Although bulk studies have demonstrated that superconductivity
+can be generally described by the Bardeen-Cooper-Schreiffer theory, the
+microscopic mechanisms of superconductivity are not yet resolved fully. The
+sensitivity of the superconducting properties to various defects of the spinel
+crystal structure provides insight into such mechanisms. Epitaxial films of
+LiTi2O4 on single crystalline substrates of MgAl2O4, MgO, and SrTiO3 provide
+model systems to systematically explore the effects of lattice strain and
+microstructural disorder. Lattice strain that affects bandwidth gives rise to
+limited variations in the superconducting and normal state properties.
+Microstructural disorder such as antiphase boundaries that give rise to Ti
+network disorder can reduce the critical temperature, but Ti network disorder
+combined with Mg interdiffusion can affect the superconducting state much more
+dramatically. Thickness dependent transport studies indicate a
+superconductor-insulator transition as a function of film thickness regardless
+of lattice strain and microstructure. In addition, surface sensitive X-ray
+absorption spectroscopy has identified Ti to retain site symmetry and average
+valence of the bulk material regardless of film thickness.",0707.0522v2
+2007-10-18,Phase behavior and dynamics of a micelle-forming triblock copolymer system,"Synperonic F-108 (generic name, 'pluronic') is a micelle forming triblock
+copolymer of type ABA, where A is polyethylene oxide (PEO) and B is
+polypropylene oxide (PPO). At high temperatures, the hydrophobicity of the PPO
+chains increase, and the pluronic molecules, when dissolved in an aqueous
+medium, self-associate into spherical micelles with dense PPO cores and
+hydrated PEO coronas. At appropriately high concentrations, these micelles
+arrange in a face centred cubic lattice to show inverse crystallization, with
+the samples exhibiting high-temperature crystalline and low-temperature
+fluidlike phases. By studying the evolution of the elastic and viscous moduli
+as temperature is increased at a fixed rate, we construct the
+concentration-temperature phase diagram of Synperonic F-108. For a certain
+range of temperatures and at appropriate sample concentrations, we observe a
+predominantly elastic response. Oscillatory strain amplitude sweep measurements
+on these samples show pronounced peaks in the loss moduli, a typical feature of
+soft solids. The soft solid-like nature of these materials is further
+demonstrated by measuring their frequency dependent mechanical moduli. The
+storage moduli are significantly larger than the loss moduli and are almost
+independent of the applied angular frequency. Finally, we perform strain rate
+frequency superposition (SRFS) experiments to measure the slow relaxation
+dynamics of this soft solid.",0710.3433v2
+2007-11-09,Study of the Electronic Structure in Oxides Using Absorption and Resonant X-Ray Scattering,"Resonant X-ray scattering (RXS) is a spectroscopy where both the power of
+site selective diffraction and the power of local absorption spectroscopy
+regarding atomic species are combined. By virtue of the dependence on the core
+level state energy and the three dimensional electronic structure of the
+intermediate state, this technique is specially suited to study charge, orbital
+or spin orderings and associated crystal distortions. In the case of charge
+ordering, we exploit the fact that atoms with closely related site symmetries
+but with small charge differences exhibit resonances at slightly different
+energies. The sensitivity of this effect allows for quantitative estimations of
+the charge disproportion. Opposite to fluorescence or absorption measurements,
+the power of diffraction relies on the capability of detecting differences that
+are smaller than the inverse lifetime of the core hole level. To account for
+the uncertainty of the crystallographic structure and the fact that the charge
+ordering must be disentangled from the associated atomic displacements, a
+complete methodology is proposed and applied to the low temperature phase of
+magnetite. Relative sensitivity on spin, toroidal and orbital ordering is also
+shown and compared in different transition metal oxide compounds, like V2O3 and
+GaFeO3.",0711.1449v1
+2007-12-04,Organic versus Hybrid Coacervate Complexes : Co-Assembly and Adsorption Properties,"We report the co-assembly and adsorption properties of coacervate complexes
+made from polyelectrolyte-neutral block copolymers and oppositely charged
+nanocolloids. The nanocolloids put under scrutiny were ionic surfactant
+micelles and highly charged 7 nm cerium oxide (CeO2) nanoparticles. Static and
+dynamic light scattering was used to investigate the microstructure and
+stability of the organic and hybrid complexes. The microstructure of the
+CeO2-based complexes was resolved using cryogenic transmission electronic
+microscopy (Cryo-TEM), and it revealed that the cores were clusters made from
+densely packed nanoparticles. In the concentration range of interest, c = 10-4
+- 1 wt. %, the surfactant-based complexes were shown to exhibit a critical
+association concentration (cac) whereas the nanoparticle-polymer hybrids did
+not. The adsorption properties of the same complexes were investigated above
+the cac by stagnation point adsorption reflectometry. The adsorbed amount was
+measured as a function of time for polymers and complexes using anionically
+charged silica and hydrophobic poly(styrene) substrates. It was found that all
+complexes adsorbed readily on both types of substrates up to a level of 1 - 2
+mg m-2 at stationary state. Upon rinsing however, the adsorbed layer was
+removed for the surfactant-based systems, but not for the cerium oxide
+clusters. As for the solution properties, these finding were interpreted in
+terms of a critical association concentrations which are very different for
+organic and hybrid complexes.",0712.0475v1
+2008-01-08,"Without Spectroscopy at the Beginning, Catalysis Research Proceeded in the Wrong Direction for More Than 100 Years","A study by infrared spectroscopy of the physisorbed region of catalysis
+demonstrated that the intermediates of catalysis exist on the surface as a two
+dimensional gas. Data in the Atomic Energy Level tables show that of the
+thousands of positive ions tabulated only approximately one hundred have the
+low-lying excited states that produce surface electric fields with a fractional
+charge. The specific catalyst for a reaction has the electric field with the
+fractional charge which when imparted to the two reactants changes the
+frequency of the fields at the sites of reaction on each so that they are
+harmonically equal, that is their ratio is a power of two. When the two
+reactants meet in the electric field of the catalyst resonance occurs. It is
+during resonance that electrons are shared, paired and exchanged and bonds are
+broken and made. This analysis of catalysis explains the most extraordinary
+observation that a catalyst is Not consumed when used because the catalyst is
+the electric fields. These discoveries are applied to explain such diverse
+reactions as the oxidation and chlorination of carbon monoxide and the
+destruction of nitric oxide in automobile exhaust. The use of electric fields
+to produce reactions may have application not only in chemistry but in biology
+and mechanics as well.",0801.1322v1
+2008-02-21,Monotonic and fatigue testing of spring-bridged freestanding microbeams application for MEMS,"Microelectromechanical systems (MEMS) technologies are developing rapidly
+with increasing study of the design, fabrication and commercialization of
+microscale systems and devices. Accurate knowledge on the mechanical behaviors
+of thin film materials used for MEMS is important for successful design and
+development of MEMS. Here a novel electroplating spring-bridge micro-tensile
+specimen integrates pin-pin align holes, misalignment compensate spring, load
+sensor beam and freestanding thin film is demonstrated and fabricated. The
+specimen is fit into a specially designed micro-mechanical apparatus to carry
+out a series of monotonic tensile testing on sub-micron freestanding thin
+films. Certain thin films applicable as structure or motion gears in MEMS were
+tested including sputtered gold, copper and tantalum nitride thin films. Metal
+specimens were fabricated by sputtering; for tantalum nitride film samples,
+nitrogen gas was introduced into the chamber during sputtering tantalum films
+on the silicon wafer. The sample fabrication method involves three steps of
+lithography and two steps of electroplating copper to hold a dog bone
+freestanding thin film. Using standard wet etching or lift off techniques, a
+series of microtensile specimens were patterned in metal thin films, holes, and
+seed layer for spring and frame structure on the underlying silicon oxide
+coated silicon substrate. Two steps of electroplating processing to distinct
+spring and frame portion of the test chip. Finally, chemical etched away the
+silicon oxide to separated electroplated specimen and silicon substrate.",0802.3083v1
+2008-03-28,High sensitivity measurement of 224Ra and 226Ra in water with an improved hydrous titanium oxide technique at the Sudbury Neutrino Observatory,"The existing hydrous titanium oxide (HTiO) technique for the measurement of
+224Ra and 226Ra in the water at the Sudbury Neutrino Observatory (SNO) has been
+changed to make it faster and less sensitive to trace impurities in the HTiO
+eluate. Using HTiO-loaded filters followed by cation exchange adsorption and
+HTiO co-precipitation, Ra isotopes from 200-450 tonnes of heavy water can be
+extracted and concentrated into a single sample of a few millilitres with a
+total chemical efficiency of 50%. Combined with beta-alpha coincidence
+counting, this method is capable of measuring 2.0x10^3 uBq/kg of 224Ra and
+3.7x10^3 uBq/kg of 226Ra from the 232Th and 238U decay chains, respectively,
+for a 275 tonne D2O assay, which are equivalent to 5x10^16 g Th/g and 3x10^16 g
+U/g in heavy water.",0803.4162v2
+2008-03-31,Superconductivity in iron-based F-doped layered quaternary compound Nd[O1-xFx]FeAs,"The recently discovered quaternary arsenide oxide superconductor
+La[O1-xFx]FeAs with the superconducting critical transition temperature (Tc) of
+26 K [1], has been quickly expanded to another high-Tc superconducting system
+beyond copper oxides by the replacement of La with other rare earth elements,
+such as Sm, Ce, and Pr etc. [2-4], and the Pr[O1-xFx]FeAs has become to be the
+first non-cuprate superconductor that holding a Tc above 50 K. All these
+arsenide (including phosphide) superconductors formed in a same tetragonal
+layered structure with the space group P4/nmm which has an alternant stacked
+Fe-As layer and RO (R = rare earth metals) layer. Here we report the discovery
+of another superconductor in this system, the neodymium-arsenide Nd[O1-xFx]FeAs
+with an resistivity onset Tc of 51.9 K, which is the second non-cuprate
+compound that superconducts above 50 K.",0803.4234v2
+2008-04-14,"Correlation Strength, Gaps and Particle-Hole Asymmetry in High-Tc Cuprates: a Dynamical Mean Field Study of the Three-Band Copper-Oxide Model","The three-band model relevant to high temperature copper-oxide
+superconductors is solved using single-site dynamical mean field theory and a
+tight-binding parametrization of the copper and oxygen bands. For a band
+filling of one hole per unit cell the metal/charge-transfer-insulator phase
+diagram is determined. The electron spectral function, optical conductivity and
+quasiparticle mass enhancement are computed as functions of electron and hole
+doping for parameters such that the corresponding to the paramagnetic metal and
+charge-transfer insulator sides of the one hole per cell phase diagram. The
+optical conductivity is computed using the Peierls phase approximation for the
+optical matrix elements. The calculation includes the physics of ""Zhang-Rice
+singlets"". The effects of antiferromagnetism on the magnitude of the gap and
+the relation between correlation strength and doping-induced changes in state
+density are determined. Three band and one band models are compared. The two
+models are found to yield quantitatively consistent results for all energies
+less than about 4eV, including energies in the vicinity of the charge-transfer
+gap. Parameters on the insulating side of the metal/charge-transfer insulator
+phase boundary lead to gaps which are too large and near-gap conductivities
+which are too small relative to data. The results place the cuprates clearly in
+the intermediate correlation regime, on the paramagnetic metal side of the
+metal/charge-transfer insulator phase boundary.",0804.2250v2
+2008-06-04,Evidence for Supercurrent Connectivity in Conglomerate Particles in NdFeAsO1-d,"Here we use global and local magnetometry and Hall probe imaging to
+investigate the electromagnetic connectivity of the superconducting current
+path in the oxygen-deficient fluorine-free Nd-based oxypnictides. High
+resolution transmission electron microscopy and scanning electron microscopy
+show strongly-layered crystallites, evidence for a ~ 5nm amorphous oxide around
+individual particles, and second phase neodymium oxide which may be responsible
+for the large paramagnetic background at high field and at high temperatures.
+  From global magnetometry and electrical transport measurements it is clear
+that there is a small supercurrent flowing on macroscopic sample dimensions
+(mm), with a lower bound for the average (over this length scale) critical
+current density of the order of 103 A/cm2. From magnetometry of powder samples
+and local Hall probe imaging of a single large conglomerate particle ~120
+microns it is clear that on smaller scales, there is better current
+connectivity with a critical current density of the order of 5 x 104 A/cm2. We
+find enhanced flux creep around the second peak anomaly in the magnetisation
+curve and an irreversibility line significantly below Hc2(T) as determined by
+ac calorimetry.",0806.0828v1
+2008-06-14,Synthesis of nanocrystalline Spinel phase by Mechanical Milling of Al-Cu-Fe and Al-Cu-Cr-Fe Quasicrystalline alloys,"In the present study, low-temperature synthesis of (Cu Fe)Al2O4 and (Cu Cr
+Fe)Al2O4 spinels from the quasicrystalline phases was investigated with the
+variation of process parameters during milling and annealing. The milling of
+the quasicrystalline materials was carried out in an attritor mill at 400 rpm
+for 40 hours with ball to powder ratio of 40:1 in hexane medium. Subsequently,
+annealing was performed in an air ambience for 10, 20, and 40 h at 400, 500,
+600 and 700 C in side a furnace in order to oxidize the mechanically milled
+quasicrystalline phase for the possible formation of the spinel phase. It was
+found that after annealing at higher temperature (500 C), mechanically milled
+quasicrystalline alloy transformed to spinel phase whereas annealing at lower
+temperature (500 C) it led to the formation of B2 phase as a major one along
+with minor amount of oxide phase. The X-ray diffraction and transmission
+electron microscopy of the annealed samples confirmed the formation of spinel
+phase with an average grain size of 20-40 nm. It is interesting to note that
+the nanospinel phases showed the different colors during various annealing time
+and temperature. The optical properties of nanospinel materials, investigated
+employing UV visible spectrometer exhibited absorption characteristics.",0806.2381v1
+2008-09-10,TiO and VO broad band absorption features in the optical spectrum of the atmosphere of the hot-Jupiter HD209458b,"The presence of titanium oxide (TiO) and vanadium oxide (VO) gas phase
+species is searched for in the atmosphere of the hot Jupiter HD209458b. We
+compared a model for the planets transmitted spectrum to multi-wavelength
+eclipse-depth measurements (from 3000 to 10000 Angstrom), obtained by Sing et
+al. (2008a) using archived HST-STIS time series spectra. We make use of these
+observations to search for spectral signatures from extra absorbers in the
+planet atmosphere between 6000 and 8000 Angstrom. Along with sodium depletion
+and Rayleigh scattering recently published for this exoplanet atmosphere, an
+extra absorber of uncertain origin, redward of the sodium lines, resides in the
+atmosphere of the planet. Furthermore, this planet has a stratosphere
+experiencing a thermal inversion caused by the capture of optical stellar flux
+by absorbers that resides at altitude. Recent models have predicted that the
+presence of TiO and VO in the atmosphere of HD209458b may be responsible for
+this temperature inversion. Although no specific TiO and VO spectral band head
+signatures have been identified unambiguously in the observed spectrum, we
+suggest here that the opacities of those molecules are possible candidates to
+explain the remaining continuous broad band absorption observed between 6200
+and 8000 Angstrom. To match reasonably well the data, the abundances of TiO and
+VO molecules are evaluated from ten to one thousand times below solar. This
+upper limit result is in agreement with expected variations with altitude due
+to depletion effects such as condensation.",0809.1865v1
+2008-11-26,Bipolar charge-carrier injection in semiconductor/insulator/conductor heterostructures: self-consistent consideration,"A self-consistent model of bipolar charge-carrier injection and transport
+processes in a semiconductor/insulator/conductor system is developed which
+incorporates space-charge effects in the description of the injection process.
+The amount of charge-carriers injected is strongly determined by the energy
+barrier emerging at the contact, but at the same time the electrostatic
+potential generated by the injected charge-carriers modifies the height of this
+injection barrier itself. In our model, self-consistency is obtained by
+assuming continuity of the electric displacement and of the electrochemical
+potential all over the system. The constituents of the system are properly
+taken into account by means of their respective density of state distributions.
+The consequences resulting from our model are discussed on the basis of an
+indium tin oxide/organic semiconductor/conductor structure. The distributions
+of the charge carriers and the electric field through the electrodes and the
+organic layer are calculated. The recombination- and current-voltage
+characteristics are analyzed for different heights of injection barriers and
+varying values of the recombination rate and compared with the measured
+current-voltage dependences for an indium tin oxide/poly(phenylene vinylene)/Ca
+structure. The voltage dependences of the recombination efficiency for the
+different values of injection barriers and recombination rate reveal optimum
+conditions for the device performance.",0811.4330v1
+2009-02-23,Can TiO Explain Thermal Inversions in the Upper Atmospheres of Irradiated Giant Planets?,"Spitzer Space Telescope infrared observations indicate that several
+transiting extrasolar giant planets have thermal inversions in their upper
+atmospheres. Above a relative minimum, the temperature appears to increase with
+altitude. Such an inversion probably requires a species at high altitude that
+absorbs a significant amount of incident optical/UV radiation. Some authors
+have suggested that the strong optical absorbers titanium oxide (TiO) and
+vanadium oxide (VO) could provide the needed additional opacity. However, if
+regions of the atmosphere are cold enough for Ti and V to be sequestered into
+solids they might rain out and be severely depleted. With a model of the
+vertical distribution of a refractory species in gaseous and condensed form, we
+address the question of whether enough TiO (or VO) could survive aloft in an
+irradiated planet's atmosphere to produce a thermal inversion. We find that,
+without significant macroscopic mixing, a heavy species such as TiO --
+especially one that can condense in a cold-trap region -- cannot persist in a
+planet's upper atmosphere. In our model, the amount of macroscopic mixing that
+would be required to loft TiO to millibar pressures ranges from ~10^7 to
+~10^{11} cm^2/s on HD 209458b, HD 149026b, TrES-4, OGLE-TR-56b, and WASP-12b,
+depending on the planet and on assumed condensate sizes. Such large values may
+be problematic for the TiO hypothesis. [Abridged]",0902.3995v2
+2009-04-21,Characterization of a naphthalene dioxygenase endowed with an exceptionally broad substrate specificity toward polycyclic aromatic hydrocarbons,"In Sphingomonas CHY-1, a single ring-hydroxylating dioxygenase is responsible
+for the initial attack of a range of polycyclic aromatic hydrocarbons (PAHs)
+composed of up to five rings. The components of this enzyme were separately
+purified and characterized. The oxygenase component (ht-PhnI) was shown to
+contain one Rieske-type [2Fe-2S] cluster and one mononuclear Fe center per
+alpha subunit, based on EPR measurements and iron assay. Steady-state kinetic
+measurements revealed that the enzyme had a relatively low apparent Michaelis
+constant for naphthalene (Km= 0.92 $\pm$ 0.15 $\mu$M), and an apparent
+specificity constant of 2.0 $\pm$ 0.3 $\mu$M-1 s-1. Naphthalene was converted
+to the corresponding 1,2-dihydrodiol with stoichiometric oxidation of NADH. On
+the other hand, the oxidation of eight other PAHs occurred at slower rates, and
+with coupling efficiencies that decreased with the enzyme reaction rate.
+Uncoupling was associated with hydrogen peroxide formation, which is
+potentially deleterious to cells and might inhibit PAH degradation. In single
+turnover reactions, ht-PhnI alone catalyzed PAH hydroxylation at a faster rate
+in the presence of organic solvent, suggesting that the transfer of substrate
+to the active site is a limiting factor. The four-ring PAHs chrysene and
+benz[a]anthracene were subjected to a double ring-dihydroxylation, giving rise
+to the formation of a significant proportion of bis-cis-dihydrodiols. In
+addition, the dihydroxylation of benz[a]anthracene yielded three dihydrodiols,
+the enzyme showing a preference for carbons in positions 1,2 and 10,11. This is
+the first characterization of a dioxygenase able to dihydroxylate PAHs made up
+of four and five rings.",0904.3254v1
+2009-04-23,Experimental and theoretical study of oxygen adsorption structures on Ag(111),"The oxidized Ag(111) surface has been studied by a combination of
+experimental and theoretical methods, scanning tunneling microscopy (STM),
+x-ray photoelectron spectroscopy (XPS), and density functional theory (DFT). A
+large variety of different surface structures is found, depending on the
+detailed preparation conditions. The observed structures fall into four
+classes: (a) individually chemisorbed atomic oxygen atoms, (b) three different
+oxygen overlayer structures, including the well-known p(4 x 4) phase, formed
+from the same Ag$_6$ and Ag$_{10}$ building blocks, (c) a c(4 x 8) structure
+not previously observed, and (d) at higher oxygen coverages structures
+characterized by stripes along the high-symmetry directions of the Ag(111)
+substrate. Our analysis provides a detailed explanation of the atomic-scale
+geometry of the Ag$_6$/Ag$_{10}$ building block structures, and the c(4 x 8)
+and stripe structures are discussed in detail. The observation of many
+different and co-existing structures implies that the O/Ag(111) system is
+characterized by a significantly larger degree of complexity than previously
+anticipated, and this will impact our understanding of oxidation catalysis
+processes on Ag catalysts.",0904.3734v2
+2009-06-15,Coexistence of Fermi arcs and Fermi pockets in a high Tc copper oxide superconductor,"In the pseudogap state of the high-Tc copper-oxide (cuprate) superconductors,
+angle-resolved photoemission (ARPES) measurements have seen an Fermi arc, i.e.,
+an open-ended gapless section in the large Fermi surface, rather than a closed
+loop expected of an ordinary metal. This is all the more puzzling because Fermi
+pockets (small closed Fermi surface features) have been suggested from recent
+quantum oscillation measurements. The Fermi arcs have worried the high-Tc
+community for many years because they cannot be understood in terms of existing
+theories. Theorists came up with a way out in the form of conventional Fermi
+surface pockets associated with competing order, with a back side that is for
+detailed reasons invisible by photoemission. Here we report ARPES measurements
+of La-Bi2201 that give direct evidence of the Fermi pocket. The charge carriers
+in the pocket are holes and the pockets show an unusual dependence upon doping,
+namely, they exist in underdoped but not overdoped samples. A big surprise is
+that these Fermi pockets appear to coexist with the Fermi arcs. This
+coexistence has not been expected theoretically and the understanding of the
+mysterious pseudogap state in the high-Tc cuprate superconductors will rely
+critically on understanding such a new finding.",0906.2682v2
+2009-10-05,Simultaneous Nitrogen-Doping and Reduction of Graphene Oxide,"We develop a simple chemical method to obtain bulk quantities of N-doped,
+reduced graphene oxide (GO) sheets through thermal annealing of GO in ammonia.
+X-ray photoelectron spectroscopy (XPS) study of GO sheets annealed at various
+reaction temperatures reveals that N-doping occurs at a temperature as low as
+300C, while the highest doping level of ~5% N is achieved at 500C. N-doping is
+accompanied by the reduction of GO with decreases in oxygen levels from ~28% in
+as-made GO down to ~2% in 1100C NH3 reacted GO. XPS analysis of the N binding
+configurations of doped GO finds pyridinic N in the doped samples, with
+increased quaternary N (N that replaced the carbon atoms in the graphene plane)
+in GO annealed at higher temperatures (>900C). Oxygen groups in GO were found
+responsible for reactions with NH3 and C-N bond formation. Pre-reduced GO with
+fewer oxygen groups by thermal annealing in H2 exhibits greatly reduced
+reactivity with NH3 and lower N-doping level. Electrical measurements of
+individual GO sheet devices demonstrate that GO annealed in NH3 exhibits higher
+conductivity than those annealed in H2, suggesting more effective reduction of
+GO by annealing in NH3 than in H2, consistent with XPS data. The N-doped
+reduced GO shows clearly n-type electron doping behavior with Dirac point (DP)
+at negative gate voltages in three terminal devices. Our method could lead to
+the synthesis of bulk amounts of N-doped, reduced GO sheets useful for various
+practical applications.",0910.0862v1
+2009-10-15,Graphene on Insulating Oxide Substrates: Role of Surface Dangling States,"We study the effect of insulating oxide substrates on the energy band
+structure of monolayer and bilayer graphene using a first principles density
+functional based electronic structure method and a local exchange correlation
+approximation. We consider two crystalline substrates, SiO2 (or alpha-quartz)
+and Al2O3 (alpha-alumina or sapphire), each with two surface terminations. We
+focus on the role of substrate surface dangling states and their passivation in
+perturbing the linear energy spectrum of graphene. On non-passivated surface
+terminations, with the relaxation of top surface layers, only Si-terminated
+quartz retains the linear band structure of graphene due to relatively large
+equilibrium separation from the graphene layer whereas the other three surface
+terminations considerably distort it. However, without relaxations of the top
+surface layer atoms, linear bands appear in the electronic spectrum but with
+the Dirac point shifted away from the Fermi level. Interestingly, with a second
+carbon layer on non-passivated oxygen terminated Quartz, with top surface
+layers relaxation, graphene features appear in the spectrum but sapphire with
+both surface terminations shows perturbed features even with two carbon layers.
+By passivating the surface dangling states with hydrogen atoms and without top
+layer atomic relaxations, the electron-hole symmetry occurs exactly at the
+Fermi level. This suggests that surface dangling states play a less important
+role than the atomic relaxations of the top surface layers in distorting the
+linear spectrum. In all cases we find that the first layer of graphene forms
+ripples, much like in suspended graphene, but the strength of rippling is found
+to be weaker probably due to the presence of the substrate.",0910.2999v2
+2009-11-14,Nanostructured Europium Oxide thin films deposited by pulsed laser ablation of a metallic target in a He buffer atmosphere,"Nanostrucured Europium oxide and hydroxide films were obtained by pulsed
+Nd:Yag (532 nm) laser ablation of an Europium metallic target, in the presence
+of a 1 mbar Helium buffer atmosphere. Both the produced film and the ambient
+plasma were characterized. The plasma was monitored by an electrostatic probe,
+for plume expansion in vacuum or in the presence of the buffer atmosphere. The
+time evolution of the ion saturation current was obtained for several probe to
+substrate distances. The results show the splitting of the plume into two
+velocity groups, being the lower velocity profile associated with metal cluster
+formation within the plume. The films were obtained in the presence of helium
+atmosphere, for several target to substrate distances. They were analyzed by
+Rutherford backscattering spectrometry (RBS), X-Ray Diffraction (XRD) and
+Atomic Force Microscopy, for samples as-deposited and treated at 600 degrees C
+in air. The results show that the as-deposited samples are amorphous and have
+chemical composition compatible with Europium hydroxide. The thermally treated
+samples show X-Ray diffraction peaks of Eu_2O_3, with chemical composition
+showing excess oxygen. Film nanostructuring was shown to be strongly correlated
+to cluster formation, as shown by velocity splitting in probe current versus
+time plots.",0911.2790v3
+2010-03-26,Growth of solid conical structures during multistage drying of sessile poly(ethylene oxide) droplets,"Sessile droplets of aqueous poly(ethylene oxide) solution, with average
+molecular weight of 100 kDa, are monitored during evaporative drying at ambient
+conditions over a range of initial concentrations $c_0$. For all droplets with
+$c_0 \geq 3%$, central conical structures, which can be hollow and nearly 50%
+taller than the initial droplet, are formed during a growth stage. Although the
+formation of superficially similar structures has been explained for
+glass-forming polymers using a skin-buckling model which predicts the droplet
+to have constant surface area during the growth stage (L. Pauchard and C.
+Allain, Europhys. Lett., 2003, 62, 897-903), we demonstrate that this model is
+not applicable here as the surface area is shown to increase during growth for
+all $c_0$. We interpret our experimental data using a proposed drying and
+deposition process comprising the four stages: pinned drying; receding contact
+line; bootstrap growth, during which the liquid droplet is lifted upon
+freshly-precipitated solid; and late drying. Additional predictions of our
+model, including a criterion for predicting whether a conical structure will
+form, compare favourably with observations. We discuss how the specific
+chemical and physical properties of PEO, in particular its amphiphilic nature,
+its tendency to form crystalline spherulites rather than an amorphous glass at
+high concentrations and its anomalous surface tension values for MW = 100 kDa
+may be critical to the observed drying process.",1003.5150v1
+2010-03-29,In-situ quantitative measurement of electric fields in zinc oxide thin films using electrostatic force microscopy,"Zinc oxide (ZnO) is the most important material for the fabrication of modern
+varistors (variable resistors). It is known that the highly nonlinear
+current-voltage relationship of ZnO varistors is due to effects taking place at
+the grain boundaries. For an accurate investigation of the mechanism of this
+process, techniques are required that allow a direct observation of local
+electric fields in varistor samples. The objective of this study is to show
+that an atomic force microscope in a set-up as an electrostatic force
+microscope is capable of the in-situ observation and measurement of an applied
+electric field in samples of ZnO thin films. The technique of Surface Potential
+Imaging was used to investigate laterally applied electric fields in this type
+of sample for the first time. The local change of the electric field across the
+samples was monitored and quantified. It was observed here that the morphology
+of the surface is convoluted into the surface potential images and the
+magnitude of this effect was quantified by taking surface potential images
+without an applied electric field. For the given measurement conditions, a
+height difference of 80 nm in the topography image resulted in a voltage
+difference of roughly 66 mV in the surface potential image. A simple model was
+provided that attributes this observation to the surroundings of the surface
+atom closest to the imaging tip.",1003.5427v1
+2010-08-13,Strain-voltage and current-voltage Scanning Probe Microscopy (SPM) response of ionic semiconductor thin films: probing of deformation potential,"We performed analytical calculations of the current-voltage and
+strain-voltage response of the heterostructure like ""charged SPM tip electrode
+/ gap / ionic-semiconductor film"" caused by the local changes of (a) ions
+concentration (stoichiometry contribution); (b) acceptors (donors) charge state
+(recharging contribution via ionic radius variation); (c) free electrons
+(holes) concentration (electron-phonon coupling via the deformation potential).
+The contribution (b) into the strain-voltage SPM was not calculated previously,
+while the contribution (c) was not even predicted before, while our estimations
+performed for correlated oxides show that strength of (c) appeared comparable
+with (a,b). For the case of ion-blocking tip and substrate electrode mainly the
+changes in holes (electrons) concentration contribute into the
+voltage-dependent mechanical displacement of the film surface, directly
+registered by strain SPM. Thus, we predict that the SPM measurements of the
+ionic semiconductor surface displacement could provide important information
+about the local changes of the acceptors (donors) charge state and electron
+(hole)-phonon correlations via the deformation potential. We obtained the great
+variety of the nonlinear static and dynamic current-voltage and strain-voltage
+hysteresis loops in the ionic semiconductor thin film with mobile acceptors
+(donors) and holes (electrons). Some types of the current-voltage hysteresis
+with pronounced memory window and double loops are observed experimentally in
+the correlated oxides and resistive switching materials like p-La1-xSrxMnO3-d
+and La1-xSrxCoO3-d, while predicted strain-voltage hysteresis of
+piezoelectric-like and butterfly-like shape requires experimental justification
+by SPM.",1008.2389v1
+2010-10-28,Long electron dephasing length and disorder-induced spin-orbit coupling in indium tin oxide nanowires,"We have measured the quantum-interference magnetoresistances in two single
+indium tin oxide (ITO) nanowires between 0.25 and 40 K, by using the four-probe
+configuration method. The magnetoresistances are compared with the
+one-dimensional weak-(anti)localization theory to extract the electron
+dephasing length $L_\phi$. We found, in a 60-nm diameter nanowire with a low
+resistivity of $\rho$(10 K) = 185 $\mu \Omega$ cm, that $L_\phi$ is long,
+increasing from 150 nm at 40 K to 520 nm at 0.25 K. Therefore, the nanowire
+reveals strict one-dimensional weak-localization effect up to several tens of
+degrees of Kelvin. In a second 72-nm diameter nanowire with a high resistivity
+of $\rho$(10 K) = 1030 $\mu \Omega$ cm, the dephasing length is suppressed to
+$L_\phi$(0.26 K) = 200 nm, and thus a crossover of the effective device
+dimensionality from one to three occurs at about 12 K. In particular,
+disorder-induced spin-orbit coupling is evident in the latter sample,
+manifesting weak-antilocalization effect at temperatures below $\sim$ 4 K.
+These observations demonstrate that versatile quantum-interference effects can
+be realized in ITO nanowires by controlling differing levels of atomic defects
+and impurities.",1010.5863v1
+2011-01-03,"A Self-consistent DFT+DMFT scheme in the Projector Augmented Wave : Applications to Cerium, Ce2O3 and Pu2O3 with the Hubbard I solver and comparison to DFT+U","An implementation of full self-consistency over the electronic density in the
+DFT+DMFT framework on the basis of a plane wave-projector augmented wave (PAW)
+DFT code is presented. It allows for an accurate calculation of the total
+energy in DFT+DMFT within a plane wave approach. In contrast to frameworks
+based on the maximally localized Wannier function, the method is easily applied
+to f electron systems, such as cerium, cerium oxide (Ce2O3) and plutonium oxide
+(Pu2O3). In order to have a correct and physical calculation of the energy
+terms, we find that the calculation of the self-consistent density is
+mandatory. The formalism is general and does not depend on the method used to
+solve the impurity model. Calculations are carried out within the Hubbard I
+approximation, which is fast to solve, and gives a good description of strongly
+correlated insulators. We compare the DFT+DMFT and DFT+U solutions, and
+underline the qualitative differences of their converged densities. We
+emphasize that in contrast to DFT+U, DFT+DMFT does not break the spin and
+orbital symmetry. As a consequence, DFT+DMFT implies, on top of a better
+physical description of correlated metals and insulators, a reduced occurrence
+of unphysical metastable solutions in correlated insulators in comparison to
+DFT+U.",1101.0539v2
+2011-01-20,Novel Superconducting Phases in Copper Oxides and Iron-oxypnictides: NMR Studies,"We reexamine the novel phase diagrams of antiferromagnetism (AFM) and
+high-Tc$ superconductivity (HTSC) for a disorder-free CuO$_2$ plane based on an
+evaluation of local hole density ($p$) by site-selective Cu-NMR studies on
+multilayered copper oxides. Multilayered systems provide us with the
+opportunity to research the characteristics of the disorder-free CuO$_2$ plane.
+The site-selective NMR is the best and the only tool used to extract
+layer-dependent characteristics. Consequently, we have concluded that the
+uniform mixing of AFM and SC is a general property inherent to a single CuO$_2$
+plane in an underdoped regime of HTSC. The $T$=0 phase diagram of AFM
+constructed here is in quantitative agreement with the theories in a strong
+correlation regime which is unchanged even with mobile holes. This {\it Mott
+physics} plays a vital role for mediating the Cooper pairs to make $T_c$ of
+HTSC very high. By contrast, we address from extensive NMR studies on
+electron-doped iron-oxypnictides La1111 compounds that the increase in $T_c$ is
+not due to the development of AFM spin fluctuations, but because the structural
+parameters, such as the bond angle $\alpha$ of the FeAs$_4$ tetrahedron and the
+a-axis length, approach each optimum value. Based on these results, we propose
+that a stronger correlation in HTSC than in FeAs-based superconductors may make
+$T_c$ higher significantly.",1101.3928v2
+2011-01-26,Multiple superconducting gap and anisotropic spin fluctuations in iron arsenides: Comparison with nickel analog,"We present extensive 75As NMR and NQR data on the superconducting arsenides
+PrFeAs0.89F0.11 (Tc=45 K), LaFeAsO0.92F0.08 (Tc=27 K), LiFeAs (Tc = 17 K) and
+Ba0.72K0.28Fe2As2 (Tc = 31.5 K) single crystal, and compare with the nickel
+analog LaNiAsO0.9F0.1 (Tc=4.0 K) . In contrast to LaNiAsO0.9F0.1 where the
+superconducting gap is shown to be isotropic, the spin lattice relaxation rate
+1/T1 in the Fe-arsenides decreases below Tc with no coherence peak and shows a
+step-wise variation at low temperatures. The Knight shift decreases below Tc
+and shows a step-wise T variation as well. These results indicate spinsinglet
+superconductivity with multiple gaps in the Fe-arsenides. The Fe
+antiferromagnetic spin fluctuations are anisotropic and weaker compared to
+underdoped copper-oxides or cobalt-oxide superconductors, while there is no
+significant electron correlations in LaNiAsO0.9F0.1. We will discuss the
+implications of these results and highlight the importance of the Fermi surface
+topology.",1101.5014v1
+2011-04-08,CO Oxidation Facilitated by Robust Surface States on Au-Covered Topological Insulators,"Surface states refer to electronic states emerging as a solid material
+terminates at a surface, and can be present in many systems. Despite their
+spatial proximity to material surfaces, surface states have been largely
+overlooked in fundamental understanding of surface catalysis and potential
+real-world applications, because of their vulnerability to local impurities or
+defects. In contrast, the recently discovered three-dimensional topological
+insulators (3DTI) have exceptionally robust metallic surface states that are
+topologically protected against surface contamination and imperfection. The
+robust topological surface state(s) (TSS) provides a perfect platform for
+exploiting novel physical phenomena and potential applications of surface
+states in less stringent environments. Here we employ first-principles density
+functional theory to demonstrate that the TSS can play a vital and elegant role
+in facilitating surface reactions by serving as an effective electron bath. We
+use CO oxidation on gold-covered Bi2Se3 as a prototype example, and first show
+that the TSS is preserved when a stable ultrathin Au film is deposited onto a
+Bi-terminated Bi2Se3 substrate. Furthermore, the TSS can significantly enhance
+the adsorption energy of both CO and O2 molecules, by promoting different
+directions of electron transfer. For CO, the TSS accepts electrons from the
+CO-Au system, thereby decreasing the undesirable occupation of the CO
+antibonding states. For O2, the TSS donates the needed electrons to promote the
+molecule towards dissociative adsorption. The present study adds a new arena to
+the technological potentials of 3DTI, and the central concept of TSS as an
+electron bath as revealed here may lead to new design principles beyond the
+conventional d-band theory of heterogeneous catalysis.",1104.1467v1
+2011-04-13,Impact of lithium composition on the thermoelectric properties of the layered cobalt oxide system LixCoO2,"Thermoelectric properties of the layered cobalt oxide system LixCoO2 were
+investigated in a wide range of Li composition, 0.98 >= x >= 0.35. Single-phase
+bulk samples of LixCoO2 were successfully obtained through electrochemical
+deintercalation of Li from the pristine LiCoO2 phase. While LixCoO2 with x >=
+0.94 is semiconductive, the highly Li-deficient phase (0.75 >= x >= 0.35)
+exhibits metallic conductivity. The magnitude of Seebeck coefficient at 293 K
+(S293K) significantly depends on the Li content (x). The S293K value is as
+large as +70 ~ +100 uV/K for x >= 0.94, and it rapidly decreases from +90 uV/K
+to +10 uV/K as x is lowered within a Li composition range of 0.75 >= x >= 0.50.
+This behavior is in sharp contrast to the results of x <= 0.40 for which the
+S293K value is small and independent of x (+10 uV/K), indicating that a
+discontinuous change in the thermoelectric characteristics takes place at x =
+0.40 ~ 0.50. The unusually large Seebeck coefficient and metallic conductivity
+are found to coexist in a narrow range of Li composition at about x = 0.75. The
+coexistence, which leads to an enhanced thermoelectric power factor, may be
+attributed to unusual electronic structure of the two-dimensional CoO2 block.",1104.2419v2
+2011-04-28,Metal-insulator transition on SrTiO$_{3}$ surface induced by ionic-bombardment,"SrTiO$_{3}$ is one of the most popular insulating single-crystal substrates
+for various complex-oxide thin film growths, because of its good lattice match
+with many complex oxide films. Here, we show that a common thin film processing
+technique, argon ion-milling, creates highly conducting layer on the surface of
+STO, not only at room temperatures but also at cryogenic temperatures at which
+thermal diffusion is completely suppressed. Systematic \emph{in situ}
+four-point conductance measurements were taken on single-crystal STO substrates
+inside vacuum environment. The evolution of metallicity out of insulating STO
+follows simple models based on oxygen vacancy doping effect. At cryogenic
+temperatures, ion milling created a thin - but much thicker than the
+argon-penetration depth - steady-state oxygen-vacant layer, leading to a
+highly-concentric metallic state. Near room temperatures, however, significant
+thermal diffusion occurred and the metallic state continuously diffused into
+the bulk, leaving only low concentraion of electron carriers on the surface.
+Analysis of the discrepancy between the experiments and the models also
+provided evidence for vacany clustering, which seems to occur during any
+vacancy formation process and affects the observed conductance. These
+observations suggest that the transport properties of films processed on STO
+substrates using energetic methods such as ion milling need to be taken with
+caution. On the other hand, if properly controlled, ionic bombardment could be
+used as a way to create selective conducting layers on the surface of STO for
+device applications.",1104.5522v3
+2011-05-10,Drying and deposition of poly(ethylene oxide) droplets determined by Péclet number,"We report results of a detailed experimental investigation into the drying of
+sessile droplets of aqueous poly(ethylene oxide) (PEO) polymer solutions under
+various experimental conditions. Samples are prepared with a range of initial
+concentrations c_0 and are filtered to remove traces of undissolved PEO
+clusters. In typical experiments, droplets with initial volumes between 5\muL
+and 50\muL are left to evaporate while temperature and relative humidity are
+monitored. Droplets either form a disk-like solid ""puddle"" or a tall conical
+""pillar"". The droplet mass is monitored using a microbalance and the droplet
+profile is recorded regularly using a digital camera. Subsequent processing of
+the data allows values of droplet volume V, surface area A, base radius R,
+contact angle {\theta} and height h to be determined throughout drying. From
+this data we identify four stages during pillar formation: pinned drying;
+pseudo-dewetting; bootstrap building; solid contraction and propose physical
+models to explain key aspects of each stage and to predict the transition from
+each stage to the next. The experimental parameters of relative humidity,
+temperature, pressure, droplet volume and initial contact angle are all
+systematically varied and observed to influence the drying process and
+consequently whether the droplet forms a pillar or a puddle. We combine these
+parameters into a dimensionless P\'eclet number Pe, which compares the relative
+effects of evaporation and diffusion, and show that the drying behaviour is
+only dependent on c_0 and Pe.",1105.1927v1
+2011-06-23,Noise and microresonance of critical current in Josephson junction induced by Kondo trap states,"We analyze the impact of trap states in the oxide layer of a superconducting
+tunnel junctions, on the fluctuation of the Josephson critical current, thus on
+coherence in superconducting qubits. Two mechanisms are usually considered: the
+current blockage due to repulsion at the occupied trap states, and the noise
+from electrons hopping across a trap. We extend previous studies of
+noninteracting traps to the case where the traps have on-site electron
+repulsion inside one ballistic channel. The repulsion not only allows the
+appropriate temperature dependence of 1/f noise, but also is a control to the
+coupling between the computational qubit and the spurious two-level systems
+inside the oxide dielectric. We use second order perturbation theory which
+allows to obtain analytical formulae for the interacting bound states and
+spectral weights, limited to small and intermediate repulsions. Remarkably, it
+still reproduces the main features of the model as identified from the
+Numerical Renormalization Group. We present analytical formulations for the
+subgap bound state energies, the singlet-doublet phase boundary, and the
+spectral weights. We show that interactions can reverse the supercurrent across
+the trap. We finally work out the spectrum of junction resonators for qubits in
+the presence of on-site repulsive electrons and analyze its dependence on
+microscopic parameters that may be controlled by fabrication.",1106.4794v3
+2011-07-29,Study of radiation damage induced by 12 keV X-rays in MOS structures built on high resistivity n-type silicon,"Imaging experiments at the European X-ray Free Electron Laser (XFEL) require
+silicon pixel sensors with extraordinary performance specifications: Doses of
+up to 1 GGy of 12 keV photons, up to 10^5 12 keV photons per pixel of 200 \mum
+\times 200 \mum arriving within less than 100 fs, and a time interval between
+XFEL pulses of 220 ns. To address these challenges, in particular the question
+of radiation damage, the properties of the SiO_2 layer and of the Si-SiO_2
+interface using MOS capacitors manufactured on high resistivity n-type silicon
+irradiated to X-ray doses between 10 kGy and 1 GGy, have been studied.
+Measurements of Capacitance/Conductance-Voltage (C/G-V) at different
+frequencies, as well as Thermal Dielectric Relaxation Current (TDRC) have been
+performed. The data can be described by a radiation dependent oxide charge
+density and three dominant radiation-induced interface states with
+Gaussian-like energy distributions in the silicon band gap. It is found that
+the densities of the fixed oxide charges and of the three interface states
+increase up to dose values of approximately 10 MGy and then saturate or even
+decrease. The shapes and the frequency dependences of the C/G-V measurements
+can be quantitatively described by a simple model using the parameters
+extracted from the TDRC measurements.",1107.5949v2
+2011-09-24,Structure and electronic structure of Metal-Organic Frameworks within the Density-Functional based Tight-Binding method,"Density-functional based tight-binding is a powerful method to describe large
+molecules and materials. Metal-Organic Frameworks (MOFs), materials with
+interesting catalytic properties and with very large surface areas have been
+developed and have become commercially available. Unit cells of MOFs typically
+include hundreds of atoms, which make the application of standard
+Density-Functional methods computationally very expensive, sometimes even
+unfeasible. The aim of this paper is to prepare and to validate the
+Self-Consistent Charge Density-Functional based Tight Binding (SCC-DFTB) method
+for MOFs containing Cu, Zn and Al metal centers. The method has been validated
+against full hybrid density-functional calculations for model clusters, against
+gradient corrected density-functional calculations for supercells, and against
+experiment. Moreover, the modular concept of MOF chemistry has been discussed
+on the basis of their electronic properties. We concentrate on MOFs comprising
+three common connector units: copper paddlewheels (HKUST-1), zinc oxide Zn4O
+tetrahedron (MOF-5, MOF-177, DUT-6 (MOF-205)) and aluminium oxide AlO4(OH)2
+octahedron (MIL-53). We show that SCC-DFTB predicts structural parameters with
+a very good accuracy (with less than 5% deviation, even for adsorbed CO and H2O
+on HKUST-1), while adsorption energies differ by 12 kJ mol-1 or less for CO and
+water compared to DFT benchmark calculations.",1109.5312v1
+2011-09-26,Radiation damage of polyethylene exposed in the stratosphere at an altitude of 40 km,"Low Density Polyethylene (LDPE) films were exposed at an altitude of 40 km
+over a 3 day NASA stratospheric balloon mission from Alice Springs, Australia.
+The radiation damage, oxidation and nitration in the LDPE films exposed in
+stratosphere were measured using ESR, FTIR and XPS spectroscopy. The results
+were compared with those from samples stored on the ground and exposed in a
+laboratory plasma. The types of free radicals, unsaturated hydrocarbon groups,
+oxygen-containing and nitrogen-containing groups in LDPE film exposed in the
+stratosphere and at the Earth's surface are different. The radiation damage in
+films exposed in the stratosphere are observed in the entire film due to the
+penetration of high energy cosmic rays through their thickness, while the
+radiation damage in films exposed on the ground is caused by sunlight
+penetrating into only a thin surface layer. A similarly thin layer of the film
+is damaged by exposure to plasma due to the low energy of the plasma particles.
+The intensity of oxidation and nitration of LDPE films reflects the difference
+of atmospheric pressure on the ground and in the stratosphere. The high-density
+radiation damage of the LDPE films above the ozone layer in the stratosphere is
+caused by primary cosmic rays as well as collision induced cosmic ray air
+showers, and is consistent with the measured flux of cosmic radiation. The
+results show, that stratospheric flights can be used to simulate the effects of
+space environments during interplanet space flights for the purposes of
+investigating the degradation of polymer materials.",1109.5457v1
+2011-09-27,Affect of film thickness on the blue photoluminescence from ZnO,"Zinc oxide (ZnO) films having various thicknesses were synthesized on
+sapphire substrates by thermal oxidation of Zn-metallic films in air ambient.
+X-ray diffraction (XRD) spectra indicate that the resulting films possess a
+polycrystalline hexagonal wurtzite structure without preferred orientation. For
+films having a thickness of 200 nm, crystal grain size was observed to decrease
+with increasing annealing temperature up to 600C, and then increase at higher
+temperatures. Thicker films demonstrated a modest increase in grain size as
+temperature increased from 300C to 1200C. The influence of film thickness on
+the optical properties was investigated using room temperature
+photoluminescence (PL). Specifically, PL spectra indicate four emission bands:
+excitonic ultraviolet, blue, and deep-level green and yellow emission. The
+strongest UV emission and narrowest full width at half maximum (0.09 eV) was
+observed for films having a thickness of 200 nm and annealed at low temperature
+(300C). The ratio of deep-level green emission to UV excitonic emission was
+observed to decrease with decreasing annealing temperature, which is attributed
+to the generation of fewer oxygen vacancies and interstitial oxygen ions in the
+bulk. As film thickness decreased, we observed the emergence of blue emission
+and a significant red shift (0.15 eV) in the bandgap. The emergence of blue
+emission and the corresponding decrease in emission associated with bulk
+defects when depletion width grows relative to the bulk suggests that the
+origin of the blue emission is related to the negatively charged Zinc
+interstitials found within the deletion region near the interface.",1109.5973v2
+2012-03-14,Electron-phonon relaxation and excited electron distribution in zinc oxide and anatase,"We propose a first-principle method for evaluations of the time-dependent
+electron distribution function of excited electrons in the conduction band of
+semiconductors. The method takes into account the excitations of electrons by
+external source and the relaxation to the bottom of conduction band via
+electron-phonon coupling. The methods permits calculations of the
+non-equilibrium electron distribution function, the quasi-stationary
+distribution function with steady-in-time source of light, the time of setting
+of the quasi-stationary distribution and the time of energy loss via relaxation
+to the bottom of conduction band. The actual calculations have been performed
+for titanium dioxide in the anatase structure and zinc oxide in the wurtzite
+structure. We find that the quasi-stationary electron distribution function for
+ZnO is a fermi-like curve that rises linearly with increasing excitation energy
+whereas the analogous curve for anatase consists of a main peak and a shoulder.
+The calculations demonstrate that the relaxation of excited electrons and the
+setting of the quasi-stationary distribution occur within the time no more than
+500 fsec for ZnO and 100 fsec for anatase.
+  We also discuss the applicability of the effective phonon model with
+energy-independent electron-phonon transition probability. We find that the
+model only reproduces the trends in changing of the characteristic times
+whereas the precision of such calculations is not high. The rate of energy
+transfer to phonons at the quasi-stationary electron distribution also have
+been evaluated and the effect of this transfer on the photocatalyses has been
+discussed. We found that for ZnO this rate is about 5 times less than in
+anatase.",1203.3033v1
+2012-07-04,Prediction of under pickling defects on steel strip surface,"An extremely important part of the finishing line is the pickling process, in
+which oxides formed during the hot rolling stage are removed from the surface
+of the steel sheets. The efficiency of the pickling process is mainly dependent
+on the nature of the oxide present at the surface of the steel, but, also, on
+process parameters such as bath composition and time duration are relevant.
+When acid concentration, solution temperatures and line speed are not properly
+balanced, in fact, sheet defects like under pickling or over pickling may
+happen and their occurrence does have a very serious effect on cold-reduction
+performance and surface appearance of the finished product. Furthermore,
+product damage from handling or improper equipment adjustment can render the
+steel unsuitable for further processing. This is the reason why it is important
+that process significant parameters are controlled and maintained as accurately
+as possible in order to avoid these undesired phenomena. In the present work, a
+control algorithm, composed by two different modules, i.e. decision tree and
+rectangular Basis Function Network, has been implemented to aim of predicting
+pickling defects and suggesting the optimal speed or the admissible speed range
+of the steel strip in the process line. In this way the most suitable line
+speed value can be set in an automatic way or by the technical personnel.",1207.0911v1
+2012-07-11,Subsurface chemistry of mantles of interstellar dust grains in dark molecular cores,"Context. The abundances of many observed compounds in interstellar molecular
+clouds still lack an explanation, despite extensive research that includes both
+gas and solid (dust-grain surface) phase reactions. Aims. We aim to
+qualitatively prove the idea that a hydrogen-poor subsurface chemistry on
+interstellar grains is responsible for at least some of these chemical
+""anomalies"". This chemistry develops in the icy mantles when photodissociation
+reactions in the mantle release free hydrogen, which escapes the mantle via
+diffusion. This results in serious alterations of the chemical composition of
+the mantle because pores in the mantle provide surfaces for reactions in the
+new, hydrogen-poor environment. Methods. We present a simple kinetic model,
+using existing astrochemical reaction databases. Gas phase, surface and
+subsurface pore reactions are included, as are physical transformations of
+molecules. Results. Our model produces significantly higher abundances for
+various oxidized species than most other models. We also obtain quite good
+results for some individual species that have adequate reaction network. Thus,
+we consider that the hydrogen-poor mantle chemistry may indeed play a role in
+the chemical evolution of molecular clouds. Conclusions. The significance of
+outward hydrogen diffusion has to be proved by further research. A huge number
+of solid phase reactions between many oxidized species is essential to obtain
+good, quantitative modeling results for a comparison with observations. We
+speculate that a variety of unobservable hydrogen-poor sulfur oxoacid
+derivatives may be responsible for the ""disappearance"" of sulfur in dark cloud
+cores.",1207.2689v1
+2012-08-05,Flexible Organic Photovoltaic Cells with In-situ Non-thermal Photoreduction of Spin Coated Graphene Oxide Electrodes,"This article is withdrawn since it is published in a journal
+  We report on the first reduction methodology, compatible with flexible,
+temperature sensitive substrates, for the production of reduced spin coated
+graphene oxide (GO) electrodes. It is based on the use of a laser beam for the
+in-situ, non-thermal, reduction of spin coated GO films on flexible substrates
+over a large area. The photoreduction process is one-step, facile and is
+rapidly carried out at room temperature in air without affecting the integrity
+of the graphene lattice as well as the flexibility of the underlying substrate.
+Conductive graphene films with a sheet resistance of as low as 700 {\Omega}/sq
+can be obtained, much higher than flexible layers reduced by chemical means. As
+a proof of concept of our technique, the laser-reduced GO (LrGO) films were
+utilized as the transparent electrode in flexible, bulk heterojunction, organic
+photovoltaic (OPV) devices, replacing the traditional ITO. The devices
+displayed a power-conversion efficiency of 1.1 %, which is the highest reported
+so far for OPV device incorporating reduced GO as the transparent electrode.
+The in-situ non-thermal photoreduction of spin-coated GO films creates a new
+way to produce flexible functional graphene electrodes for a variety of
+electronic applications in a process that carries substantial promise for
+potential industrial implementation.",1208.0988v3
+2012-11-12,"Cation nonstoichiometry and its impact on nucleation, structure and defect formation in complex oxide heteroepitaxy : LaCrO3 on SrTiO3(001)","Our ability to design and fabricate electronic devices with reproducible
+properties using complex oxides is critically dependent on our ability to
+controllably synthesize these materials in thin-film form. Structure-property
+relationships are intimately tied to film and interface composition. Here we
+report on the effects of cation stoichiometry in LaCrO3 heteroepitaxial films
+prepared using molecular beam epitaxy. We show that LaCrO3 films grow
+pseudomorphically on SrTiO3(001) over a wide range of La-to-Cr atom ratios.
+However, the growth mode and structural quality are sensitive to the La-to-Cr
+ratio, with La-rich films being of considerably lower structural quality than
+Cr-rich films. Cation mixing occurs at the interface for all La-to-Cr ratios
+investigated, and is not quenched by deposition at ambient temperature.
+Indiffused La atoms occupy Sr sites in the substrate. The presence of defects
+in the SrTiO3 substrate is implicated in promoting La indiffusion by comparing
+the properties of LaCrO3/SrTiO3 with those of LaCrO3/Si, both prepared at
+ambient temperature. Additionally, pulsed laser deposition is shown to result
+in more extensive interfacial mixing than molecular beam epitaxy for deposition
+at ambient temperature on Si.",1211.2850v1
+2012-11-24,Ab initio modelling of UN grain boundary interfaces,"The uranium mononitride (UN) is a material considered as a promising
+candidate for Generation-IV nuclear reactor fuels. Unfortunately, oxygen in air
+affects UN fuel performance and stability. Therefore, it is necessary to
+understand the mechanism of oxygen adsorption and further UN oxidation in the
+bulk and at surface. Recently, we performed a detailed study on oxygen
+interaction with UN surface using density functional theory (DFT) calculations.
+We were able to identify an atomistic mechanism of UN surface oxidation
+consisting of several important steps, starting with the oxygen molecule
+dissociation and finishing with oxygen atom incorporation into vacancies on the
+surface. However, in reality most of processes occur at the interfaces and on
+UN grain boundaries. In this study, we present the results of first DFT
+calculations on O behaviour inside UN grain boundaries performed using GGA
+exchange-correlation functional PW91 as implemented into the VASP computer
+code. We consider a simple interface (310)[001](36.8{\deg}) tilt grain
+boundary. The N vacancy formation energies and energies of O incorporation into
+pre-existing vacancies in the grain boundaries as well as O solution energies
+were compared with those obtained for the UN (001) and (110) surfaces.",1211.5693v1
+2012-11-26,Plasmonic resonances in nanostructured transparent conducting oxide films,"Transparent conducting oxides (TCO) are emerging as possible alternative
+constituent materials to replace noble metals such as silver and gold for
+low-loss plasmonic and metamaterial (MMs) applications in the near infrared
+(NIR) regime. The optical characteristics of TCOs have been studied to evaluate
+the functionalities and potential of these materials as metal substitutes in
+plasmonic and MM devices, even apart from their usual use as electrode
+materials. However, patterning TCOs at the nanoscale, which is necessary for
+plasmonic and MM devices, is not well-studied. This paper investigates
+nanopatterning processes for TCOs, especially the lift-off technique with
+electron-beam lithography, and the realization of plasmonic nanostructures with
+TCOs. By employing the developed nanopatterning process, we fabricate
+2D-periodic arrays of TCO nanodisks and characterize the material's plasmonic
+properties to evaluate the performance of TCOs as metal substitutes.
+Light-induced collective oscillations of the free electrons in the TCOs (bulk
+plasmons) and localized surface plasmon resonances are observed in the
+wavelength range from 1.6 to 2.1 micron. Well-defined resonance peaks are
+observed, which can be dramatically tuned by varying the amount of dopant and
+by thermally annealing the TCO nanodisks in nitrogen gas ambient while
+maintaining the low-loss properties.",1211.5988v1
+2012-12-07,Poly(acrylic acid)-coated iron oxide nanoparticles : quantitative evaluation of the coating properties and applications for the removal of a pollutant dye,"In this work, 6 to 12 nm iron oxide nanoparticles were synthesized and coated
+with poly(acrylic acid) chains of molecular weight 2100 g/mol. Based on a
+quantitative evaluation of the dispersions, the bare and coated particles were
+thoroughly characterized. The number densities of polymers adsorbed at the
+particle surface and of available chargeable groups were found to be 1.9 +/-
+0.3 nm-2 and 26 +/- 4 nm-2, respectively. Occurring via a multi-site binding
+mechanism, the electrostatic coupling leads to a solid and resilient anchoring
+of the chains. To assess the efficacy of the particles for pollutant
+remediation, the adsorption isotherm of methylene blue molecules, a model of
+pollutant, was determined. The excellent agreement between the predicted and
+measured amounts of adsorbed dyes suggests that most carboxylates participate
+to the complexation and adsorption mechanisms. An adsorption of 830 mg/g was
+obtained. This quantity compares well with the highest values available for
+this dye.",1212.1580v1
+2012-12-11,Photoluminescence and High Temperature Persistent Photoconductivity Experiments in SnO2 Nanobelts,"The Persistent Photoconductivity (PPC) effect was studied in individual tin
+oxide (SnO2) nanobelts as a function of temperature, in air, helium, and vacuum
+atmospheres, and low temperature Photoluminescence measurements were carried
+out to study the optical transitions and to determine of the acceptor/donors
+levels and their best representation inside the band gap. Under ultraviolet
+(UV) illumination and at temperatures in the range of 200 to 400K we observed a
+fast and strong enhancement of the photoconductivity, and the maximum value of
+the photocurrent induced increases as the temperature or the oxygen
+concentration decreases. By turning off the UV illumination the induced
+photocurrent decays with lifetimes up to several hours. The photoconductivity
+and the PPC results were explained by adsorption and desorption of molecular
+oxygen at the surface of the SnO2 nanobelts. Based on the temperature
+dependence of the PPC decay an activation energy of 230 meV was found, which
+corresponds to the energy necessary for thermal ionization of free holes from
+acceptor levels to the valence band, in agreement with the photoluminescence
+results presented. The molecular-oxygen recombination with holes is the origin
+of the PPC effect in metal oxide semiconductors, so that, the PPC effect is not
+related to the oxygen vacancies, as commonly presented in the literature.",1212.2550v1
+2013-02-13,Disappearance of Nodal Gap across the Insulator-Superconductor Transition in a Copper-Oxide Superconductor,"The parent compound of the copper-oxide high temperature superconductors is a
+Mott insulator. Superconductivity is realized by doping an appropriate amount
+of charge carriers. How a Mott insulator transforms into a superconductor is
+crucial in understanding the unusual physical properties of high temperature
+superconductors and the superconductivity mechanism. Here we report high
+resolution angle-resolved photoemission measurement on heavily underdoped
+Bi2Sr2-xLaxCuO6+d system. The electronic structure of the lightly-doped samples
+exhibit a number of characteristics: existence of an energy gap along the nodal
+direction, d-wave-like anisotropic energy gap along the underlying Fermi
+surface, and coexistence of a coherence peak and a broad hump in the
+photoemission spectra. Our results reveal a clear insulator-superconductor
+transition at a critical doping level of ~0.10 where the nodal energy gap
+approaches zero, the three-dimensional antiferromagnetic order disappears, and
+superconductivity starts to emerge. These observations clearly signal a close
+connection between the nodal gap, antiferromagnetism and superconductivity.",1302.3017v2
+2013-02-13,Probing electron transport across a LSMO/Nb:STO heterointerface at the nanoscale,"We investigate electron transport across a complex oxide heterointerface of
+La$_{0.67}$Sr$_{0.33}$MnO$_3$ (LSMO) on Nb:SrTiO$_3$ (Nb:STO) at different
+temperatures. For this, we employ the conventional current-voltage method as
+well as the technique of Ballistic Electron Emission Microscopy (BEEM), which
+can probe lateral inhomogeneities in transport at the nanometer scale. From
+current-voltage measurements, we find that the Schottky Barrier height (SBH) at
+the LSMO/Nb:STO interface decreases at low temperatures accompanied by a larger
+than unity ideality factor. This is ascribed to the tunneling dominated
+transport caused by the narrowing of the depletion width at the interface.
+However, BEEM studies of such unbiased interfaces, do not exhibit SBH lowering
+at low temperatures, implying that this is triggered by the modification of the
+interface due to an applied bias and is not an intrinsic property of the
+interface. Interestingly, the SBH at the nanoscale, as extracted from BEEM
+studies, at different locations in the device is found to be spatially
+homogeneous and similar both at room temperature and at low temperatures. Our
+results highlight the application of BEEM in characterizing electron transport
+and their homogeneity at such unbiased complex oxide interfaces and yields new
+insights into the origin of the temperature dependence of the SBH at biased
+interfaces.",1302.3187v1
+2013-03-23,Keck II Observations of Hemispherical Differences in H2O2 on Europa,"We present results from Keck II observations of Europa over four consecutive
+nights using the near-infrared spectrograph (NIRSPEC). Spectra were collected
+in the 3.14--4.0 micron range, allowing detection and monitoring of the 3.5
+micron feature due to hydrogen peroxide. Galileo Near-Infrared Spectrometer
+(NIMS) results first revealed hydrogen peroxide on Europa in the anti-jovian
+region of the leading hemisphere at an abundance of 0.13+/-0.07% by number
+abundance relative to water. We find comparable results for the two nights over
+which we observed the leading hemisphere. Significantly, we observed a small
+amount of hydrogen peroxide (~0.04%) during observations of Europa's anti- and
+sub-Jovian hemispheres. Almost no hydrogen peroxide was detected during
+observations of just the trailing hemisphere. We conclude that the Galileo
+observations likely represent the maximum hydrogen peroxide concentration, the
+exception potentially being the cold water ice regions of the poles, which are
+not readily observable from the ground. Our mapping of the peroxide abundance
+across Europa requires revisions to previous estimates for Europa's global
+surface abundance of oxidants and leads to a reduction in the total oxidant
+delivery expected for the sub-surface ocean, if exchange of surface material
+with the ocean occurs.",1303.5895v1
+2013-04-11,Intrinsic Spin Hall Effect at Oxide Interfaces: a Simple Model,"An asymmetric triangular potential well provides the simplest model for the
+confinement of mobile electrons at the interface between two insulating oxides,
+such as LaAlO_3 and SrTiO_3 (LAO/STO). These electrons have been recently shown
+to exhibit a large spin-orbit coupling of the Rashba type, i.e., linear in the
+in-plane momentum. In this paper we study the intrinsic spin Hall effect due to
+Rashba coupling in an asymmetric triangular potential well. Besides splitting
+each subband into two branches of opposite helicity, the spin-orbit interaction
+causes the wave function in the direction perpendicular to the plane of the
+quantum well (the z direction) to depend on the in-plane wave vector k. In
+contrast to the extreme asymmetric case, i.e., the wedge-shaped quantum well,
+for which the intrinsic spin Hall effect vanishes due to vertex corrections, we
+find that the asymmetric well supports a non-vanishing intrinsic spin Hall
+conductivity, which increases in magnitude as the well becomes more symmetric.
+The spin Hall conductivity is found to be proportional to the square of the
+spin-orbit coupling constant and, in the limit of low carrier density, depends
+only on the effective mass renormalization associated with the k-dependence of
+the wave functions in the z direction. Its origin lies in the non-vanishing
+matrix elements of the spin current between subbands corresponding to different
+states of quantized motion perpendicular to the plane of the well.",1304.3476v2
+2013-05-04,Interfacial activity of phosphonated-polyethylene glycol functionalized cerium oxide nanoparticles,"In a recent publication, we have highlighted the potential of phosphonic acid
+terminated PEG oligomers to functionalize strong UV absorption cerium oxide
+nanoparticles[1], which yield suspensions that are stable in aqueous or organic
+solvents and are redispersible in different solvent after freeze-drying. In the
+present work, we highlight the interfacial activity of the functional ceria
+nanoparticles and their potential to modify hydrophobic surfaces. We first
+investigated Phosphonated-PEG amphiphilic oligomers behavior as strong surface
+active species forming irreversibly adsorbed layers. We then show that the
+oligomers interfacial properties translate to the functional nanoparticles. In
+particular, the addition of a small fraction of phosphonated-PEG oligomers with
+an extra C16 aliphatic chain (stickers) into the formulation enabled the tuning
+of i) the nanoparticles adsorption at the air/water, polystyrene/water,
+oil/water interfaces and ii) the particle/particle interaction in aqueous
+solutions. We also found that dense and closely packed two dimensional
+monolayers of nanoceria can be formed by spontaneous adsorption or surface
+compression using a Langmuir trough. A hexagonal organization controlled by
+reversible and repulsive repulsion has been characterized by GISAXS. Mono- or
+multilayers can also be stably formed or transferred on solid surfaces. Our
+results are key features in the field of polymer surface modification, solid
+stabilized emulsions (Pickering) or supracolloidal assemblies.",1305.0898v1
+2013-05-15,Nanoscale order in the frustrated mixed conductor La$_{5.4}WO$_{12-δ}$,"We report a comprehensive investigation of the average and local structure of
+La$_{5.4}$WO$_{12-\delta}$, which has excellent mixed proton, electron and
+oxide ion conduction suitable for device applications. Synchrotron X-ray and
+neutron powder diffraction show that a cubic fluorite supercell describes the
+average structure, with highly disordered lanthanum and oxide positions. On
+average the tungsten sites are six-fold coordinated, and we detect a trace
+(4.4(2) %) of anti-site disorder. In addition to sharp Bragg reflections,
+strong diffuse neutron scattering is observed, which hints at short-range
+order. We consider plausible local configurations, and show that the defect
+chemistry implies a simple 'chemical exchange' interaction that favours ordered
+WO6 octahedra. Our local model is confirmed by synchrotron x-ray pair
+distribution function analysis and EXAFS experiments performed at the La K and
+W L3-edges. We show that ordered domains of around ca. 3.5 nm are found,
+implying that mixed conduction in La$_{5.4}$WO$_{12-\delta}$? is associated
+with a defective glassy-like anion sublattice. The origins of this ground state
+are proposed to lie in the non-bipartite nature of the fcc lattice and the
+pairwise interactions which link the orientation of neighbouring octahedral WO6
+sites. This 'function through frustration' could provide a means of designing
+new mixed conductors.",1305.3385v1
+2013-05-30,Kelvin Probe Microscopy and Electronic Transport Measurements in Reduced Graphene Oxide Chemical Sensors,"Reduced Graphene Oxide (RGO) is an electronically hybrid material that
+displays remarkable chemical sensing properties. Here, we present a
+quantitative analysis of the chemical gating effects in RGO-based chemical
+sensors. The gas sensing devices are patterned in a field-effect transistor
+geometry, by dielectrophoretic assembly of RGO platelets between gold
+electrodes deposited on SiO2/Si substrates. We show that these sensors display
+highly selective and reversible responses to the measured analytes, as well as
+fast response and recovery times (tens of seconds). We use combined electronic
+transport/Kelvin Probe Microscopy measurements to quantify the amount of charge
+transferred to RGO due to chemical doping when the device is exposed to
+electron-acceptor (acetone) and electron-donor (ammonia) analytes. We
+demonstrate that this method allows us to obtain high-resolution maps of the
+surface potential and local charge distribution both before and after chemical
+doping, to identify local gate-susceptible areas on the RGO surface, and to
+directly extract the contact resistance between the RGO and the metallic
+electrodes. The method presented is general, suggesting that these results have
+important implications for building graphene and other nanomaterial-based
+chemical sensors.",1305.7222v1
+2013-06-05,Method and Advantages of Genetic Algorithms in Parameterization of Interatomic Potentials: Metal-Oxides,"The method and the advantages of an evolutionary computing based approach
+using a steady state genetic algorithm (GA) for the parameterization of
+interatomic potentials for metal oxides within the shell model framework are
+developed and described. We show that the GA based methodology for the
+parameterization of interatomic force field functions is capable of (a)
+simultaneous optimization of the multiple phases or properties of a material in
+a single run, (b) facilitates the incremental re-optimization of the whole
+system as more data is available for either additional phases or material
+properties not included in previous runs, and (c) successful global
+optimization in the presence of multiple local minima in the parameter space.
+As an example, we apply the method towards simultaneous optimization of four
+distinct crystalline phases of Barium Titanate (BaTiO3 or BTO) using an ab
+initio density functional theory (DFT) based reference dataset. We find that
+the optimized force field function is capable of the prediction of the two
+phases not used in the optimization procedure, and that many derived physical
+properties such as the equilibrium lattice constants, unit cell volume, elastic
+properties, coefficient of thermal expansion, and average electronic
+polarization are in good agreement with the experimental results available from
+the literature.",1306.1196v1
+2013-07-10,Seeding ice growth at ambient conditions using nano graphene oxide,"Water wetting on a hydrophobic surface at ambient conditions is disallowed by
+the nonpolar nature of the surface and high vapor pressure of water. However,
+the presence of sub-millimeter sized hydrophilic patches allows the waxy wings
+of desert beetles to become wettable by morning mist. Here, we show that a
+sprinkle of graphene oxide nanoflakes (nanoGOs) is effective in condensing
+water nanodroplets and seeding ice epitaxy on graphite at ambient conditions.
+By controlling relative humidity and nanoGO density, we are able to study the
+formation of a complete ice wetting layer on a time scale of 20 hours. This
+presents an unprecedented opportunity to visualize ice nucleation and growth in
+real time using non-contact atomic force microscopy. The stages of
+crystallization, as proposed by Ostwald in 1897, is fully unfolded at a
+microscopic level for the first time. We obtain real-time imaging of sequential
+phase transition from amorphous ice to a transient cubic ice Ic stage and
+finally to the stable hexagonal ice Ih. Most interestingly, we discover that
+ice nucleation and growth can be influenced by modifying the functional groups
+of nanoGO, and by intermolecular hydrogen-bonding between nanoGOs. This affords
+a strategy to control heterogenous ice nucleation and snow crystal formation.",1307.2673v1
+2013-07-17,"Sorption of 4He, H2, Ne, N2, CH4 and Kr impurities in graphene oxide at low temperatures. Quantum effects","Sorption and the subsequent desorption of 4He, H2,Ne, N2, CH4 and Kr gas
+impurities by graphene oxide (GO), glucose-reduced GO (RGO-Gl) and
+hydrazine-reduced GO (RGO-Hz) powders have been investigated in the temperature
+interval 2-290 K. It has been found that the sorptive capacity of the reduced
+sample RGO-Hz is three to six times higher than that of GO. The reduction of GO
+with glucose has only a slight effect on its sorptive properties. The
+temperature dependences of the diffusion coefficients of the GO, RGO-Gl and
+RGO-Hz samples have been obtained using the measured characteristic times of
+sorption. It is assumed that the temperature dependences of the diffusion
+coefficients are determined by the competition of the thermally activated and
+tunneling mechanisms, the tunneling contribution being dominant at low
+temperatures.",1307.4528v1
+2013-07-29,Evidence for hydrogen two-level systems in atomic layer deposition oxides,"Two-level system (TLS) defects in dielectrics are known to limit the
+performance of electronic devices. We study TLS using millikelvin microwave
+loss measurements of three atomic layer deposited (ALD) oxide
+films--crystalline BeO ($\rm{c-BeO}$), amorphous $\rm{Al_2O_3}$
+($\rm{a-Al_2O_3}$), and amorphous $\rm{LaAlO_3}$ ($\rm{a-LaAlO_3}$)--and
+interpret them with room temperature characterization measurements. We find
+that the bulk loss tangent in the crystalline film is 6 times higher than in
+the amorphous films. In addition, its power saturation agrees with an amorphous
+distribution of TLS. Through a comparison of loss tangent data to secondary ion
+mass spectrometry (SIMS) impurity analysis we find that the dominant loss in
+all film types is consistent with hydrogen-based TLS. In the amorphous films
+excess hydrogen is found at the ambient-exposed surface, and we extract the
+associated hydrogen-based surface loss tangent. Data from films with a factor
+of 40 difference in carbon impurities revealed that carbon is currently a
+negligible contributor to TLS loss.",1307.7664v1
+2013-10-15,Reduced graphene oxide thin films as ultrabarriers for organic electronics,"Encapsulation of electronic devices based on organic materials that are prone
+to degradation even under normal atmospheric conditions with hermetic barriers
+is crucial for increasing their lifetime. A challenge is to develop
+'ultrabarriers' that are impermeable, flexible, and preferably transparent.
+Another important requirement is that they must be compatible with organic
+electronics fabrication schemes (i.e. must be solution processable, deposited
+at room temperature and be chemically inert). Here, we report lifetime increase
+of 1,300 hours for poly(3-hexylthiophene) (P3HT) films encapsulated by uniform
+and continuous thin (~10 nm) films of reduced graphene oxide (rGO). This level
+of protection against oxygen and water vapor diffusion is substantially better
+than conventional polymeric barriers such as CytopTM, which degrades after only
+350 hours despite being 400 nm thick. Analysis using atomic force microscopy,
+x-ray photoelectron spectroscopy and high resolution transmission electron
+microscopy suggest that the superior oxygen gas/moisture barrier property of
+rGO is due to the close interlayer distance packing and absence of pinholes
+within the impermeable sheets. These material properties can be correlated to
+the enhanced lag time of 500 hours. Our results provide new insight for the
+design of high performance and solution processable transparent 'ultrabarriers'
+for a wide range of encapsulation applications.",1310.3915v1
+2013-10-22,Electron sampling depth and saturation effects in perovskite films investigated by soft x-ray absorption spectroscopy,"Knowledge of the electron sampling depth and related saturation effects is
+important for quantitative analysis of X-ray absorption spectroscopy data, yet
+for oxides with the perovskite structure no quantitative values are so far
+available. Here we study absorption saturation in films of two of the
+most-studied perovskites, LCMO and YBCO, at the L2,3 edge of Mn and Cu,
+respectively. By measuring the electron-yield intensity as a function of photon
+incidence angle and film thickness, the sampling depth d, photon attenuation
+length, lambda, and the ratio lambda/d have been independently determined
+between 50 and 300 K. The extracted sampling depth dLCMO=3 nm for LCMO at high
+temperatures in its polaronic insulator state (150-300K) is not much larger
+than values reported for pure transition metals (d Co or Ni=2-2.5nm) at room
+temperature, but it is smaller than dYBCO=3.9 nm for metallic YBCO that is in
+turn smaller than the value reported for Fe3O4 (d=4.5 nm) The measured dLCMO
+increases to 4.5 nm when LCMO is in the metallic state at low temperatures.
+These results indicate that a universal rule of thumb for the sampling depth in
+oxides cannot be assumed, and that it can be measurably influenced by
+electronic phase transitions that derive from strong correlations.",1310.5998v1
+2013-10-23,Neutron scattering measurements of $dd$ and spin-orbit excitations below the Mott-Hubbard gap in CoO,"Neutron scattering is used to investigate the single-ion spin and orbital
+excitations below the Mott-Hubbard gap in CoO. Three excitations are reported
+at 0.870 $\pm$ 0.009 eV, 1.84 $\pm$ 0.03, and 2.30 $\pm$ 0.15 eV. These were
+parameterized within a weak crystal field scheme with an intra-orbital exchange
+of $J(dd)$=1.3 $\pm$ 0.2 eV and a crystal field splitting 10Dq=0.94 $\pm$ 0.10
+eV. A reduced spin-orbit coupling of \lambda=-0.016 $\pm$ 0.003 eV is derived
+from dilute samples of Mg$_{0.97}$Co$_{0.03}$O, measured to remove
+complications due to spin exchange and structural distortion parameters which
+split the cubic phase degeneracy of the orbital excitations complicating the
+inelastic spectrum. The 1.84 eV, while reported using resonant x-ray and
+optical techniques, was absent or weak for non resonant x-ray experiments and
+overlaps with the expected position of a $^{4}A_{2}$ level. This transition is
+absent in the dipolar approximation but expected to have a finite quadrupolar
+matrix element that can be observed with neutron scattering techniques at
+larger momentum transfers. Our results agree with a crystal field analysis (in
+terms of Racah parameters and Tanabe-Sugano diagrams) and with previous
+calculations performed using local-density band theory for Mott insulating
+transition metal oxides. The results also demonstrate the use of neutron
+scattering for measuring dipole forbidden transitions in transition metal oxide
+systems.",1310.6207v1
+2013-11-09,Atomized Spraying of Liquid Metal Droplets on Desired Substrate Surfaces as a Generalized Way for Ubiquitous Printed Electronics,"A direct electronics printing technique through atomized spraying for
+patterning room temperature liquid metal droplets on desired substrate surfaces
+is proposed and experimentally demonstrated for the first time. This method has
+generalized purpose and is highly flexible and capable of fabricating
+electronic components on any desired target objects, with either flat or rough
+surfaces, made of different materials, or different orientations from 1-D to
+3-D geometrical configurations. With a pre-designed mask, the liquid metal ink
+can be directly deposited on the substrate to form various specific patterns
+which lead to the rapid prototyping of electronic devices. Further, extended
+printing strategies were also suggested to illustrate the adaptability of the
+method such that the natural porous structure can be adopted to offer an
+alternative way of making transparent conductive film with an optical
+transmittance of 47% and a sheet resistance of 5.167{\Omega}/O. Different from
+the former direct writing technology where large surface tension and poor
+adhesion between the liquid metal and the substrate often impede the flexible
+printing process, the liquid metal here no longer needs to be pre-oxidized to
+guarantee its applicability on target substrates. One critical mechanism was
+found as that the atomized liquid metal microdroplets can be quickly oxidized
+in the air due to its large specific surface area, resulting in a significant
+increase of the adhesive capacity and thus firm deposition of the ink to the
+substrate. This study established a generalized way for pervasively and
+directly printing electronics on various substrates which are expected to be
+significant in a wide spectrum of electrical engineering areas.",1311.2158v1
+2013-12-17,A Network Biology Approach to Denitrification in Pseudomonas aeruginosa,"Pseudomonas aeruginosa is a metabolically flexible member of the
+Gammaproteobacteria. Under anaerobic conditions and the presence of nitrate, P.
+aeruginosa can perform (complete) denitrification, a respiratory process of
+dissimilatory nitrate reduction to nitrogen gas via nitrite ($NO_{2}$), nitric
+oxide ($NO$) and nitrous oxide ($N_{2}O$). This study focuses on understanding
+the influence of environmental conditions on bacterial denitrification
+performance, using a mathematical model of a metabolic network in P.
+aeruginosa. To our knowledge, this is the first mathematical model of
+denitrification for this bacterium. Analysis of the long-term behavior of the
+network under changing concentration levels of oxygen ($O_{2}$), nitrate
+($NO_{3}$), and phosphate ($PO_{4}$) suggests that $PO_{4}$ concentration
+strongly affects denitrification performance. The model provides five
+predictions on denitrification activity of P. aeruginosa under various
+environmental conditions, and these predictions are either experimentally
+validated or supported by pertinent biological literature. One motivation for
+this study is to capture the effect of $PO_{4}$ on a denitrification metabolic
+network of P. aeruginosa in order to shed light on mechanisms for greenhouse
+gas $N_{2}O$ accumulation during seasonal oxygen depletion in aquatic
+environments such as Lake Erie (Laurentian Great Lakes, USA).",1312.4616v3
+2013-12-29,Asymmetric band widening by screened exchange competing with local correlations in SrVO3: new surprises on an old compound from combined GW and dynamical mean field theory GW+DMFT,"The very first dynamical implementation of the combined GW and dynamical mean
+field scheme ""GW+DMFT"" for a real material was achieved recently [J.M. Tomczak
+et al., Europhys. Lett. 100 67001 (2012)], and applied to the ternary
+transition metal oxide SrVO3. Here, we review and extend that work, giving not
+only a detailed account of full GW+DMFT calculations, but also discussing and
+testing simplified approximate schemes. We give insights into the nature of
+exchange and correlation effects: Dynamical renormalizations in the Fermi
+liquid regime of SrVO3 are essentially local, and nonlocal correlations mainly
+act to screen the Fock exchange term. The latter substantially widens the
+quasi-particle band structure, while the band narrowing induced by the former
+is accompanied by a spectral weight transfer to higher energies. Most
+interestingly, the exchange broadening is much more pronounced in the
+unoccupied part of spectrum. As a result, the GW+DMFT electronic structure of
+SrVO3 resembles the conventional density functional based dynamical mean field
+(DFT+DMFT) description for occupied states, but is profoundly modified in the
+empty part. Our work leads to a reinterpretation of inverse photoemission
+spectroscopy (IPES) data. Indeed, we assign a prominent peak at about 2.7 eV
+dominantly to eg states, rather than to an upper Hubbard band of t2g character.
+Similar surprises can be expected for other transition metal oxides, calling
+for more detailed investigations of the conduction band states.",1312.7546v1
+2014-01-06,Evidence for a charge collective mode associated with superconductivity in copper oxides from neutron and x-ray scattering measurements of La$_{2-x}$Sr$_x$CuO$_4$,"In superconducting copper oxides some Cu-O bond-stretching phonons around
+70meV show anomalous giant softening and broadening of electronic origin and
+electronic dispersions have large renormalization kinks near the same energy.
+These observations suggest that phonon broadening originates from quasiparticle
+excitations across the Fermi surface and the electronic dispersion kinks
+originate from coupling to anomalous phonons. We measured the phonon anomaly in
+underdoped (x=0.05) and overdoped (x=0.20,0.25) La$_{2-x}$Sr$_x$CuO$_4$ by
+inelastic neutron and x-ray scattering with high resolution. Combining these
+and previously published data, we found that doping-dependence of the magnitude
+of the giant phonon anomaly is very different from that of the ARPES kink, i.e.
+the two phenomena are not connected. We show that these results provide
+indirect evidence that the phonon anomaly originates from novel collective
+charge excitations as opposed to interactions with electron-hole pairs. Their
+amplitude follows the superconducting dome so these charge modes may be
+important for superconductivity.",1401.1111v2
+2014-02-03,Efficacy of the DFT+U formalism for modeling hole polarons in perovskite oxides,"We investigate the formation of self-trapped holes (STH) in three
+prototypical perovskites (SrTiO3, BaTiO3, PbTiO3) using a combination of
+density functional theory (DFT) calculations with local potentials and hybrid
+functionals. First we construct a local correction potential for polaronic
+configurations in SrTiO3 that is applied via the DFT+U method and matches the
+forces from hybrid calculations. We then use the DFT+U potential to search the
+configuration space and locate the lowest energy STH configuration. It is
+demonstrated that both the DFT+U potential and the hybrid functional yield a
+piece-wise linear dependence of the total energy on the occupation of the STH
+level suggesting that self-interaction effects have been properly removed. The
+DFT+U model is found to be transferable to BaTiO3 and PbTiO3, and formation
+energies from DFT+U and hybrid calculations are in close agreement for all
+three materials. STH formation is found to be energetically favorable in SrTiO3
+and BaTiO3 but not in PbTiO3, which can be rationalized by considering the
+alignment of the valence band edges on an absolute energy scale. In the case of
+PbTiO3 the strong coupling between Pb 6s and O 2p states lifts the valence band
+minimum (VBM) compared to SrTiO3 and BaTiO3. This reduces the separation
+between VBM and STH level and renders the STH configuration metastable with
+respect to delocalization (band hole state). We expect that the present
+approach can be adapted to study STH formation also oxides with different
+crystal structures and chemical composition.",1402.0435v1
+2014-02-13,Fractal and Multifractal Analysis of the Rise of Oxygen in Earth's Early Atmosphere,"The rise of oxygen in Earth's atmosphere that occurred 2.4 to 2.2 billion
+years ago is known as the Earth's Great Oxidation, and its impact on the
+development of life on Earth has been profound. Thereafter, the increase in
+Earth's oxygen level persisted, though at a more gradual pace. The proposed
+underlying mathematical models for these processes are based on physical
+parameters whose values are currently not well-established owing to
+uncertainties in geological and biological data. In this paper, a previously
+developed model of Earth's atmosphere is modified by adding different strengths
+of noise to account for the parameters' uncertainties. The effects of the noise
+on the time variations of oxygen, carbon and methane for the early Earth are
+investigated by using fractal and multifractal analysis. We show that the time
+variations following the Great Oxidation cannot properly be described by a
+single fractal dimension because they exhibit multifractal characteristics. The
+obtained results demonstrate that the time series as obtained exhibit
+multifractality caused by long-range time correlations.",1402.3243v4
+2014-04-03,Short-Range Structure and Phonon Assignment of the Brownmillerite-Type Oxide Ba$_{2}$In$_{2}$O$_{5}$ and its Hydrated Proton-Conducting Form BaInO$_{3}$H,"The vibrational spectra and short-range structure of the brownmillerite-type
+oxide Ba$_{2}$In$_{2}$O$_{5}$ and its hydrated form BaInO$_{3}$H, are
+investigated by means of Raman, infrared, and inelastic neutron scattering
+spectroscopies together with density functional theory calculations. For
+Ba$_{2}$In$_{2}$O$_{5}$, which may be described as an oxygen deficient
+perovskite structure with alternating layers of InO$_{6}$ octahedra and
+InO$_{4}$ tetrahedra, the results affirm a short-range structure of $Icmm$
+symmetry, which is characterized by random orientation of successive layers of
+InO$_{4}$ tetrahedra. For the hydrated, proton conducting, form, BaInO$_{3}$H,
+the results suggest that the short-range structure is more complicated than the
+$P4/mbm$ symmetry that has been proposed previously on the basis of neutron
+diffraction, but rather suggest a proton configuration close to the lowest
+energy structure predicted by Martinez et al. [J.-R. Martinez, C. E. Moen, S.
+Stoelen, N. L. Allan, J. of Solid State Chem. 180, 3388, (2007)]. An intense
+Raman active vibration at 150 cm$^{-1}$ is identified as a unique fingerprint
+of this proton configuration.",1404.1034v2
+2014-04-08,Structure and dehydration mechanism of the proton conducting oxide Ba$_{2}$In$_{2}$O$_{5}$(H$_{2}$O)$_{x}$,"The structure and dehydration mechanism of the proton conducting oxide
+Ba$_{2}$In$_{2}$O$_{5}$(H$_{2}$O)$_{x}$ are investigated by means of variable
+temperature Raman spectroscopy together with inelastic neutron scattering. At
+room temperature, Ba$_{2}$In$_{2}$O$_{5}$(H$_{2}$O)$_{x}$ is found to be fully
+hydrated ($x=1$) and to have a perovskite-like structure, which dehydrates
+gradually with increasing temperature and at around 600 $^{\circ}$C the
+material is essentially completely dehydrated ($x=0$). The dehydrated material
+exhibits a brownmillerite structure, which is featured by alternating layers of
+InO$_{6}$ octahedra and InO$_{4}$ tetrahedra. The transition from a
+perovskite-like to a brownmillerite-like structure is featured by a
+hydrated-to-intermediate phase transition at $ca.$ 370 {\deg}C. The structure
+of the intermediate phase is similar to the structure of the fully dehydrated
+material, but with the difference that it exhibits a non-centrosymmetric
+distortion of the InO$_{6}$ octahedra not present in the latter. For
+temperatures below the hydrated-to-intermediate phase transition, dehydration
+is featured by the release of protons confined to the layers of InO$_{4}$
+tetrahedra, whereas above the transition also protons bound to oxygens of the
+layers of InO$_{6}$ are released. Finally, we found that the O-H stretch region
+of the vibrational spectra is not consistent with a single-phase spectrum, but
+is in agreement with the superposition of spectra associated with two different
+proton configurations. The relative contributions of the two proton
+configurations depend on how the sample is hydrated.",1404.2260v2
+2014-07-24,Preventing corona effects: multi-phosphonic acid poly(ethylene glycol) copolymers for stable stealth iron oxide nanoparticles,"When disperse in biological fluids, engineered nanoparticles are selectively
+coated with proteins, resulting in the formation of a protein corona. It is
+suggested that the protein corona is critical in regulating the conditions of
+entry into the cytoplasm of living cells. Recent reports describe this
+phenomenon as ubiquitous and independent of the nature of the particle. For
+nanomedicine applications however, there is a need to design advanced and
+cost-effective coatings that are resistant to protein adsorption and that
+increase the biodistribution in vivo. In this study, phosphonic acid
+poly(ethylene glycol) copolymers were synthesized and used to coat iron oxide
+particles. The copolymer composition was optimized to provide simple and
+scalable protocols as well as long-term stability in culture media. It is shown
+that polymers with multiple phosphonic acid functionalities and PEG chains
+outperform other types of coating, including ligands, polyelectrolytes and
+carboxylic acid functionalized PEG. PEGylated particles exhibit moreover
+exceptional low cellular uptake, of the order of 100 femtograms of iron per
+cell. The present approach demonstrates that the surface chemistry of
+engineered particles is a key parameter in the interactions with cells. It also
+opens up new avenues for the efficient functionalization of inorganic surfaces.",1407.6411v1
+2014-08-29,Oxygen diffusion pathways in brownmillerite SrCoO2.5: Influence of structure and chemical potential,"To design and discover new materials for next-generation energy materials
+such as solid-oxide fuel cells (SOFCs), a fundamental understanding of their
+ionic properties and behaviors is essential. The potential applicability of a
+material for SOFCs is critically determined by the activation energy barrier of
+oxygen along various diffusion pathways. In this work, we investigate
+interstitial-oxygen (Oi) diffusion in brownmillerite oxide SrCoO2.5, employing
+a first-principles approach. Our calculations indicate highly anisotropic ionic
+diffusion pathways, which result from its anisotropic crystal structure. The
+one-dimensional-ordered oxygen vacancy channels are found to provide the
+easiest diffusion pathway with an activation energy barrier height of 0.62 eV.
+The directions perpendicular to the vacancy channels have higher energy
+barriers for Oint diffusion. In addition, we have studied migration barriers
+for oxygen vacancies that could be present as point defects within the
+material. This in turn could also facilitate the transport of oxygen.
+Interestingly, for oxygen vacancies, the lowest barrier height was found to
+occur within the octahedral layer with an energy of 0.82 eV. Our results imply
+that interstitial migration would be highly one-dimensional in nature. Oxygen
+vacancy transport, on the other hand, could preferentially occur in the
+two-dimensional octahedral plane.",1408.7077v1
+2014-09-01,Nitric Oxide as stress inducer and synchronizer of p53 dynamics,"We study how the temporal behaviours of p53 and MDM2 are affected by stress
+inducing bioactive molecules NO (Nitric Oxide) in the p53-MDM2-NO regulatory
+network. We also study synchronization among a group of identical stress
+systems arranged in a three dimensional array with nearest neighbour diffusive
+coupling. The role of NO and effect of noise are investigated. In the single
+system study, we have found three distinct types of temporal behaviour of p53,
+namely, oscillation death, damped oscillation and sustain oscillation,
+depending on the amount of stress induced by the NO concentration, indicating
+how p53 responds to the incoming stress. The correlation among the coupled
+systems increases as the value of coupling constant (\epsilon) is increased
+(\gamma increases) and becomes constant after certain value of \epsilon. The
+permutation entropy spectra H(\epsilon) for p53 and MDM2 as a function of
+\epsilon are found to be different due to direct and indirect interaction of NO
+with the respective proteins. \gamma versus \epsilon for p53 and MDM2 are found
+to be similar in deterministic approach, but different in stochastic approach
+and the separation between \gamma of the respective proteins as a function of
+\epsilon decreases as system size increases. The role of NO is found to be
+twofold: stress induced by it is prominent at small and large values of
+\epsilon but synchrony inducing by it dominates in moderate range of \epsilon.
+Excess stress induce apoptosis to the system.",1409.0528v1
+2014-09-03,Mobility enhancement and temperature dependence in top-gated single-layer MoS2,"The deposition of a high-$\kappa$ oxide overlayer is known to significantly
+enhance the room-temperature electron mobility in single-layer MoS$_{2}$ (SLM)
+but not in single-layer graphene (SLG). We give a quantitative account of how
+this mobility enhancement is due to the non-degeneracy of the two-dimensional
+electron gas system in SLM at accessible temperatures. Using our charged
+impurity scattering model [Ong and Fischetti, Phys. Rev. B 86, 121409 (2012)]
+and temperature-dependent polarizability, we calculate the charged
+impurity-limited mobility ($\mu_{\textrm{imp}}$) in SLM with and without a
+high-$\kappa$ (HfO$_{2}$) top gate oxide at different electron densities and
+temperatures. We find that the mobility enhancement is larger at low electron
+densities and high temperatures because of finite-temperature screening, thus
+explaining the enhancement of the mobility observed at room temperature.
+$\mu_{\textrm{imp}}$ is shown to decrease significantly with increasing
+temperature, suggesting that the strong temperature dependence of measured
+mobilities should not be interpreted as being solely due to inelastic
+scattering with phonons. We also reproduce the recently seen experimental trend
+in which the temperature scaling exponent ($\gamma$) of
+$\mu_{\textrm{imp}}\propto T^{-\gamma}$ is smaller in top-gated SLM than in
+bare SLM. Finally, we show that a $\sim37$ percent mobility enhancement can be
+achieved by reducing the HfO$_{2}$ thickness from 20 to 2 nm.",1409.1084v1
+2014-09-23,Macromechanical behavior of oxide nanopowders during compaction processes,"Two granular systems (I and II) corresponding oxide nanopowders having
+different agglomeration tendency are simulated by the granular dynamics method.
+The particle size is 10 nanometer. The interaction of particles involves the
+elastic forces of repulsion, the tangential forces of ""friction"", the
+dispersion forces of attraction, and in the case of II system the opportunity
+of creation/destruction of hard bonds of chemical nature. The processes of the
+uniaxial compaction, the biaxial (radial) one, the isotropic one, the
+compaction combined with shear deformation as well as the simple shear
+deformation are studied. The effect of the positive dilatancy is found out in
+the processes of shear deformation. The loading surfaces of nanopowders are
+constructed in the space of stress tensor invariants, i.e., the hydrostatic
+pressure and the deviator intensity. It is revealed that the form of the
+loading surfaces is similar to an ellipse, which is shifted along the
+hydrostatic axis to compressive pressures. The associated flow rule is
+analyzed. The nonorthogonality of the deformation vectors to the loading
+surface is established in the both systems modeled.",1409.6393v1
+2014-10-06,Graphene-protected copper and silver plasmonics,"Plasmonics has established itself as a branch of physics which promises to
+revolutionize data processing, improve photovoltaics, increase sensitivity of
+bio-detection. A widespread use of plasmonic devices is notably hindered (in
+addition to high losses) by the absence of stable and inexpensive metal films
+suitable for plasmonic applications. This may seem surprising given the number
+of metal compounds to choose from. Unfortunately, most of them either exhibit a
+strong damping of surface plasmons or easily oxidize and corrode. To this end,
+there has been continuous search for alternative plasmonic materials that are,
+unlike gold, the current metal of choice in plasmonics, compatible with
+complementary metal oxide semiconductor technology. Here we show that copper
+and silver protected by graphene are viable candidates. Copper films covered
+with one to a few graphene layers show excellent plasmonics characteristics
+surpassing those of gold films. They can be used to fabricate plasmonic devices
+and survive for at least a year, even in wet and corroding conditions. As a
+proof of concept, we use the graphene-protected copper to demonstrate
+dielectric loaded plasmonic waveguides and test sensitivity of surface plasmon
+resonances. Our results are likely to initiate a wide use of graphene-protected
+plasmonics.",1410.1459v1
+2014-11-12,Quantum effects in proton-conducting oxides: an exhaustive study in barium stannate,"Density-functional theory calculations are performed to investigate hydrogen
+transport in the proton conductor BaSnO$_3$. Structural optimizations in the
+stable and saddle point configurations for transfer and reorientation allow
+description of the high-temperature classical and semi-classical regimes, in
+which diffusion occurs by over-barrier motion. At lower temperature (typically
+below 300 K), we describe a thermally-assisted quantum regime. In this regime,
+transfer and reorientation occur when the surrounding matrix adopts particular
+""coincidence"" configurations in which quantum tunneling is favored. Both the
+non-adiabatic and the adiabatic cases are examined. In the adiabatic case, the
+energy landscape of hydrogen in the coincidence configuration is very flat,
+with very low coincidence energy barriers. Path-integral molecular dynamics
+simulations of the H atom in the coincidence potential reveal, in the transfer
+case, highly quantum behavior up to T=300 K (the density of probability of H in
+the coincidence configuration, has its maximum at the saddle point, due to the
+fact that the zero-point energy exceeds the coincidence energy barrier).
+Arguments are given that support the adiabatic picture for the transfer
+mechanism. This suggests existence of this state of hydrogen during the very
+short lifetime of the coincidence configurations ($\sim$ 10$^{-13}$ s), as a
+transition state for the transfer mechanism. Remarkably, such state is
+identical to that of ice X, a highly quantum phase of ice observed at high
+pressures $\approx$ 100 GPa. In the case of reorientation, typical times for
+existence of the coincidence configuration and for protonic motion are roughly
+equal, suggesting that the adiabatic picture is not valid. Protonic transfer
+and reorientation in oxides are therefore governed by radically different
+mechanisms below room temperature.",1411.3207v1
+2014-11-15,Shock-waves and commutation speed of memristors,"Progress of silicon based technology is nearing its physical limit, as
+minimum feature size of components is reaching a mere 10 nm. The resistive
+switching behaviour of transition metal oxides and the associated memristor
+device is emerging as a competitive technology for next generation electronics.
+Significant progress has already been made in the past decade and devices are
+beginning to hit the market; however, it has been mainly the result of
+empirical trial and error. Hence, gaining theoretical insight is of essence. In
+the present work we report the striking result of a connection between the
+resistive switching and {\em shock wave} formation, a classic topic of
+non-linear dynamics. We argue that the profile of oxygen vacancies that migrate
+during the commutation forms a shock wave that propagates through a highly
+resistive region of the device. We validate the scenario by means of model
+simulations and experiments in a manganese-oxide based memristor device. The
+shock wave scenario brings unprecedented physical insight and enables to
+rationalize the process of oxygen-vacancy-driven resistive change with direct
+implications for a key technological aspect -- the commutation speed.",1411.4198v3
+2014-11-21,Water Reaction Mechanism in Metal Organic Frameworks with Coordinatively Unsaturated Metal Ions: MOF-74,"Water dissociation represents one of the most important reactions in
+catalysis, essential to the surface and nano sciences [e.g., Hass et al.,
+Science, 1998, 282, 265-268; Brown et al., Science 2001, 294, 67-69; Bikondoa
+et al., Nature 2005, 5, 189-192]. However, the dissociation mechanism on most
+oxide surfaces is not well understood due to the experimental challenges of
+preparing surface structures and characterizing reaction pathways. To remedy
+this problem, we propose the metal organic framework MOF-74 as an ideal model
+system to study water reactions. Its crystalline structure is well
+characterized; the metal oxide node mimics surfaces with exposed cations; and
+it degrades in water. Combining in situ IR spectroscopy and first-principles
+calculations, we explored the MOF-74/water interaction as a function of vapor
+pressure and temperature. Here, we show that, while adsorption is reversible
+below the water condensation pressure (~19.7 Torr) at room temperature, a
+reaction takes place at ~150 centigrades even at low water vapor pressures.
+This important finding is unambiguously demonstrated by a clear spectroscopic
+signature for the direct reaction using D2O, which is not present using H2O due
+to strong phonon coupling. Specifically, a sharp absorption band appears at 970
+cm-1 when D2O is introduced at above 150 centigrades, which we attribute to an
+O-D bending vibration on the phenolate linker. Although H2O undergoes a similar
+dissociation reaction, the corresponding O-H mode is too strongly coupled to
+MOF vibrations to detect. In contrast, the O-D mode falls in the phonon gap of
+the MOF and remains localized.",1411.5736v1
+2014-11-21,Impact of Tailored Gamma Irradiation on Pore Size and Particle Size of Poly[Ethylene Oxide]Films: Correlation with Molecular Weight Distribution andMicrostructural Study,"The structure and morphology of polymers are significantly altered upon
+exposure to high energy gamma irradiation. The present investigation reports
+the influence of such irradiation of doses in the range of 1 - 30 kGy on the
+particle size of Poly (Ethylene Oxide) [PEO] powder along with its correlation
+with molecular weight distribution. Pore-size distribution and overall porosity
+of the synthesized films prepared with irradiated and unirradiated PEO powder
+is also reported. The particle size of both unirradiated and irradiated PEO
+powders is found be in the range of 0.01 - 1000 micrometer. It is known that,
+variation in irradiation dose either generates particles of lower dimension
+through bond breakage i.e scission or higher dimension through cross-linkage.
+PEO films exhibit strong dependence of irradiation effect on pore size
+distribution and porosity. PEO films synthesized using both unirradiated and
+irradiated powders exhibit pore dimension in the range of 20 - 500 nm. The
+overall porosity of PEO films studied through BET adsorption technique
+initially increases with dose upto 3 kGy followed by linear decrease upto 30
+kGy. Films cast with unirradiated PEO powder show multimodal pore size
+distribution, but perturbation with irradiation changes the modality to uni-or
+bimodal nature. The mentioned outcome of irradiation viz. particle and pore
+size variation is also correlated with PEO microstructures.The article
+demonstrates that, selective irradiation is capable of tailoring the pore-size
+within a definite regime thereby reducing the multimodal trait. The reported
+study may be relevant towards applications such as catalysis, sensing and
+filtration, where pore size distribution plays a crucial role.",1411.5816v1
+2014-11-20,Concentration dependence of the fluorescence decay profile in transition metal doped chalcogenide glass,"In this paper we present the fluorescence decay profiles of vanadium and
+titanium doped gallium lanthanum sulphide (GLS) glass at various doping
+concentrations between 0.01 and 1% (molar). We demonstrate that below a
+critical doping concentration the fluorescence decay profile can be fitted with
+the stretched exponential function: exp[-(t/{\tau})\b{eta}], where {\tau} is
+the fluorescence lifetime and \b{eta} is the stretch factor. At low
+concentrations the lifetime for vanadium and titanium doped GLS was 30 {\mu}s
+and 67 {\mu}s respectively. We validate the use of the stretched exponential
+model and discuss the possible microscopic phenomenon it arises from. We also
+demonstrate that above a critical doping concentration of around 0.1% (molar)
+the fluorescence decay profile can be fitted with the double exponential
+function: a*exp-(t/{\tau}1)+ b*exp-(t/{\tau}2), where {\tau}1and {\tau}2 are
+characteristic fast and slow components of the fluorescence decay profile, for
+vanadium the fast and slow components are 5 {\mu}s and 30 {\mu}s respectively
+and for titanium they are 15 {\mu}s and 67 {\mu}s respectively. We also show
+that the fluorescence lifetime of vanadium and titanium at low concentrations
+in the oxide rich host gallium lanthanum oxy-sulphide (GLSO) is 43 {\mu}s and
+97 {\mu}s respectively, which is longer than that in GLS. From this we deduce
+that vanadium and titanium fluorescing ions preferentially substitute into high
+efficiency oxide sites until at a critical concentration they become saturated
+and low efficiency sulphide sites start to be filled.",1411.7045v1
+2014-12-04,Heterogeneous electrocatalysis in porous cathodes of solid oxide fuel cells,"A general physics-based model is developed for heterogeneous electrocatalysis
+in porous electrodes and used to predict and interpret the impedance of solid
+oxide fuel cells. This model describes the coupled processes of oxygen gas
+dissociative adsorption and surface diffusion of the oxygen intermediate to the
+triple phase boundary, where charge transfer occurs. The model accurately
+captures the Gerischer-like frequency dependence and the oxygen partial
+pressure dependence of the impedance of symmetric cathode cells. Digital image
+analysis of the microstructure of the cathode functional layer in four
+different cells directly confirms the predicted connection between geometrical
+properties and the impedance response. As in classical catalysis, the
+electrocatalytic activity is controlled by an effective Thiele modulus, which
+is the ratio of the surface diffusion length (mean distance from an adsorption
+site to the triple phase boundary) to the surface boundary layer length (square
+root of surface diffusivity divided by the adsorption rate constant). The
+Thiele modulus must be larger than one in order to maintain high surface
+coverage of reaction intermediates, but care must be taken in order to
+guarantee a sufficient triple phase boundary density. The model also predicts
+the Sabatier volcano plot with the maximum catalytic activity corresponding to
+the proper equilibrium surface fraction of adsorbed oxygen adatoms. These
+results provide basic principles and simple analytical tools to optimize porous
+microstructures for efficient electrocatalysis.",1412.1548v1
+2014-12-05,Resistance switching devices based on amorphous insulator-metal thin films,"Nanometallic devices based on amorphous insulator-metal thin films are
+developed to provide a novel non-volatile resistance-switching random-access
+memory (RRAM). In these devices, data recording is controlled by a bipolar
+voltage, which tunes electron localization length, thus resistivity, through
+electron trapping/detrapping. The low-resistance state is a metallic state
+while the high-resistance state is an insulating state, as established by
+conductivity studies from 2K to 300K. The material is exemplified by a Si3N4
+thin film with randomly dispersed Pt or Cr. It has been extended to other
+materials, spanning a large library of oxide and nitride insulator films,
+dispersed with transition and main-group metal atoms. Nanometallic RRAMs have
+superior properties that set them apart from other RRAMs. The critical
+switching voltage is independent of the film thickness/device
+area/temperature/switching speed. Trapped electrons are relaxed by
+electron-phonon interaction, adding stability which enables long-term memory
+retention. As electron-phonon interaction is mechanically altered, trapped
+electron can be destabilized, and sub-picosecond switching has been
+demonstrated using an electromagnetically generated stress pulse. AC impedance
+spectroscopy confirms the resistance state is spatially uniform, providing a
+capacitance that linearly scales with area and inversely scales with thickness.
+The spatial uniformity is also manifested in outstanding uniformity of
+switching properties. Device degradation, due to moisture, electrode oxidation
+and dielectrophoresis, is minimal when dense thin films are used or when a
+hermetic seal is provided. The potential for low power operation, multi-bit
+storage and complementary stacking have been demonstrated in various RRAM
+configurations.",1412.2083v1
+2014-12-16,Reaction of the desulfoferrodoxin from Desulfoarculus baarsii with superoxide anion. Evidence for a superoxide reductase activity,"Desulfoferrodoxin is a small protein found in sulfate-reducing bacteria that
+contains two independent mononuclear iron centers, one ferric and one ferrous.
+Expression of desulfoferrodoxin from Desulfoarculus baarsii has been reported
+to functionally complement a superoxide dismutase deficient Escherichia coli
+strain. To elucidate by which mechanism desulfoferrodoxin could substitute for
+superoxide dismutase in E. coli, we have purified the recombinant protein and
+studied its reactivity toward O-(2). Desulfoferrodoxin exhibited only a weak
+superoxide dismutase activity (20 units mg(-1)) that could hardly account for
+its antioxidant properties. UV-visible and electron paramagnetic resonance
+spectroscopy studies revealed that the ferrous center of desulfoferrodoxin
+could specifically and efficiently reduce O-(2), with a rate constant of 6-7 x
+10(8) M(-1) s(-1). In addition, we showed that membrane and cytoplasmic E. coli
+protein extracts, using NADH and NADPH as electron donors, could reduce the
+O-(2) oxidized form of desulfoferrodoxin. Taken together, these results
+strongly suggest that desulfoferrodoxin behaves as a superoxide reductase
+enzyme and thus provide new insights into the biological mechanisms designed
+for protection from oxidative stresses.",1412.5038v1
+2014-12-24,Impact of dopant species on the interfacial trap density and mobility in amorphous In-X-Zn-O solution-processed thin-film transistors,"Alloying of In/Zn oxides with various X atoms stabilizes the IXZO structures
+but generates electron traps in the compounds, degrading the electron mobility.
+To assess whether the latter is linked to the oxygen affinity or the ionic
+radius, of the X element, several IXZO samples are synthesized by the sol-gel
+process, with a large number (14) of X elements. The IXZOs are characterized by
+XPS, SIMS, DRX, and UV-spectroscopy and used for fabricating thin film
+transistors. Channel mobility and the interface defect density NST, extracted
+from the TFT electrical characteristics and low frequency noise, followed an
+increasing trend and the values of mobility and NST are linked by an
+exponential relation. The highest mobility (8.5 cm2/Vs) is obtained in
+In-Ga-Zn-O, and slightly lower value for Sb and Sn-doped IXZOs, with NST is
+about 2E12 cm2/eV, close to that of the In-Zn-O reference TFT. This is
+explained by a higher electronegativity of Ga, Sb, and Sn than Zn and In, their
+ionic radius values being close to that of In and Zn. Consequently, Ga, Sb, and
+Sn induce weaker perturbations of In-O and Zn-O sequences in the sol-gel
+process, than the X elements having lower electronegativity and different ionic
+radius. The TFTs with X = Ca, Al, Ni and Cu exhibited the lowest mobility and
+NST > 1E13 cm2/eV, most likely because of metallic or oxide clusters formation.",1412.7710v1
+2015-01-15,Flux growth utilizing the reaction between flux and crucible,"Flux growth involves dissolving the components of the target compound in an
+appropriate flux at high temperatures and then crystallizing under
+supersaturation controlled by cooling or evaporating the flux. A refractory
+crucible is generally used to contain the high temperature melt. The reaction
+between the melt and crucible materials can modify the composition of the melt,
+which typically results in growth failure, or contaminates the crystals. Thus
+one principle in designing a flux growth is to select suitable flux and
+crucible materials thus to avoid any reaction between them. In this paper, we
+review two cases of flux growth in which the reaction between flux and
+Al$_2$O$_3$ crucible tunes the oxygen content in the melt and helps the
+crystallization of desired compositions. For the case of La$_5$Pb$_3$O,
+Al$_2$O$_3$ crucible oxidizes La to form a passivating La$_2$O$_3$ layer which
+not only prevents further oxidization of La in the melt but also provides [O]
+to the melt. For the case of La$_{0.4}$Na$_{0.6}$Fe$_2$As$_2$, it is believed
+that the Al$_2$O$_3$ crucible reacts with NaAsO$_2$ and the reaction consumes
+oxygen in the melt thus maintaining an oxygen-free environment.",1501.03770v1
+2015-01-25,Out-of-plane Ionicity versus In-plane Covalency Interplay in High-Tc Superconducting Oxides,"It seems that the remarkable properties of the high temperature
+superconducting oxides, especially the Insulator-Metal Transition (IMT) and the
+Metal-Superconductor Transition (MST) both originate from the competition
+(interplay) between ionic versus in-plane covalence nature of bonds in these
+materials. As a result of this competition, the microscopic order parameter,
+that is firmly identified to be the local field estimated from the ionic
+polarization at the sub-unit level (one half of the unit cell), shows a strong
+temperature as well as chemical doping dependence. While the out-of-plane
+ionicity is responsible for the interlayer charge transfer (electrons) that
+reduces it leading to IMT, the in-plane covalency is responsible for the
+in-plane intersite transfer of charge (holes) that increases the ionicity and
+leads to MST. This interplay of charge transfer, driven by the out-of-plane
+ionicity and the in-plane covalency, leads at the critical temperature Tc to a
+local field avalanche (ionic polarization catastrophe at the sub-unit cell
+level) that triggers an out-of-plane correlation between the local polarization
+fields at the unit cell and drives the compound into the superconducting state.
+The asymmetry of the free charge carrier density breaks locally the inversion
+symmetry of the order parameter leading to an unconventional pairing mechanism
+characterized by the CPT transformation where C is the charge conjugation
+symmetry, P is the parity symmetry and T is the time reversal symmetry. It is
+established that the out-of-plane ionicity versus in-plane covalency is a
+necessary condition for the occurrence of both IMT and MST. The underlined
+microscopic mechanism provides a route to a possible unified description of
+high-Tc superconductivity.",1501.06134v2
+2015-02-05,Intrinsic electron mobility exceeding 1000 cm$^2$/Vs in multilayer InSe FETs,"Graphene-like two-dimensional (2D) materials, not only are interesting for
+their exotic electronic structure and fundamental electronic transport or
+optical properties but also, hold promises for device miniaturization down to
+atomic thickness. As one material belonging to this category, InSe is not only
+a promising candidate for optoelectronic devices but also has potential for
+ultrathin field effect transistor (FET) with high mobility transport. In this
+work, various substrates such as PMMA, bare silicon oxide, passivated silicon
+oxide, and silicon nitride were used to fabricate multi-layer InSe FET devices.
+Through back gating and Hall measurement in four-probe configuration, the
+devices' field effect mobility and intrinsic Hall mobility were extracted at
+various temperatures to study the material's intrinsic transport behavior and
+the effect of dielectric substrate. The sample's field effect and Hall
+mobilities over the range of 77-300K fall in the range of 0.1-2.0$\times$10$^3$
+cm$^2$/Vs, which are comparable or better than the state of the art FETs made
+of 2D transition metal-dichalcogenides.",1502.01615v3
+2015-02-06,Identification of annealing temperature for high-$κ$-based gate oxides using differential scanning calorimetry,"This article identifies the process of crystallization of thin high-$\kappa$
+dielectric films and an optimal range of annealing temperature in the field of
+high-$\kappa$ dielectric-based metal-oxide-semiconductor (MOS) technology for
+its improved electrical performances. Differential Scanning Calorimetry (DSC)
+technique is employed to understand the thermal behaviour of thin high-$\kappa$
+dielectric films of HfO$_2$, deposited by rf sputtering, on Si. The exothermic
+trends of the DSC signal and Grazing Incidence X-ray diffraction (GIXRD) data
+indicate an amorphous to crystalline transition in the high-$\kappa$ film at
+higher temperature. The enthalpy-temperature variation shows a glass
+temperature (T$_g$) at $\sim$ 590 $^o$C beyond which an amorphous to m-HfO$_2$
+crystalline transition takes place. Further, the Hf-Silicate formation,
+observed in DSC measurement and corroborated by Fourier transformed Infrared
+Spectroscopy (FT-IR) studies, indicates that the process of formation of
+Hf-Silicate begins at $\sim$ 717 $^oC$. High-frequency (HF) capacitance-voltage
+$(C-V)$ and current density - voltage $(J-V)$ characteristics establish that
+the crystallization of the film is not the root cause of degradation of the
+electrical properties of the high-$\kappa$-based MOS devices, rather the device
+degrades due to formation of interfacial Hf-Silicate.",1502.01889v2
+2015-02-26,"Structural and Dielectric Properties of (La, Nd) (Mg1/2Ti1/2)O3 Perovskites","Using the high-resolution x-ray diffraction (XRD) analysis, scanning electron
+microscopy (SEM), and the temperature-dependent microwave resonator
+characterization, structural properties, phase assemblage and dielectric
+properties of La(Mg1/2Ti1/2)O3 (LMT) and Nd(Mg1/2Ti1/2)O3 (NMT) ceramics
+prepared via the mixed oxide route were investigated in this study.
+Single-phase ceramics were synthesized for both LMT and NMT at sintering
+temperatures from 1250 degree C to 1675 degree C. On the basis of the XRD
+analysis we have found that the LMT and NMT compounds have cubic and monoclinic
+crystal structures, respectively. We have also observed that the relative
+densities of LMT and NMT vary between about 93 and 99% of the theoretical
+density, depending on the sintering temperature. Finally, concerning the
+dielectric properties of the microwave resonators made of LMT and NMT compounds
+we have measured their temperature coefficient of the resonant frequency
+({\tau}f) and the quality factor (Q). It is interesting to notice that
+({\tau}f) in the case of the NMT compound (-16 ppm 1/K) is essentially smaller
+than in the case of the LMT compound (-72 ppm 1/K), therefore proving a better
+stability against temperature variations in the NMT based resonators. On the
+other hand, the Q values are very similar, being 34000 at the resonance
+frequency of 8.07 GHz and 38000 at the resonance frequency of 9.76 GHz in the
+LMT and NMT cases, respectively.
+  Keywords: dielectric properties; microstructure-final: grain growth; single
+phase Ln(Mg0.5Ti0.5)O3 (Ln=Nd,La); Lanthanum magnesium titanium oxide.",1502.07547v1
+2015-03-01,Generalized spectral method for near-field optical microscopy,"Electromagnetic interaction between a sub-wavelength particle (the `probe')
+and a material surface (the `sample') is studied theoretically. The interaction
+is shown to be governed by a series of resonances corresponding to surface
+polariton modes localized near the probe. The resonance parameters depend on
+the dielectric function and geometry of the probe, as well as the surface
+reflectivity of the material. Calculation of such resonances is carried out for
+several types of axisymmetric probes: spherical, spheroidal, and pear-shaped.
+For spheroids an efficient numerical method is developed, capable of handling
+cases of large or strongly momentum-dependent surface reflectivity. Application
+of the method to highly resonant materials such as aluminum oxide (by itself or
+covered with graphene) reveals a rich structure of multi-peak spectra and
+nonmonotonic approach curves, i.e., the probe-sample distance dependence. These
+features also strongly depend on the probe shape and optical constants of the
+model. For less resonant materials such as silicon oxide, the dependence is
+weak, so that the spheroidal model is reliable. The calculations are done
+within the quasistatic approximation with the radiative damping included
+perturbatively.",1503.00221v2
+2015-03-10,Defect and Temperature Dependence of Tunneling in InAs/GaSb Heterojunctions,"Tunnel field effect transistors (TFETs) utilizing semiconductor
+heterojunctions have shown promise for low energy logic but presently do not
+display subthreshold swings steeper than the room-temperature thermal limit of
+60 mV/decade. These devices also show a pronounced temperature dependence that
+is not characteristic of a tunneling process. Herein, we explore these aspects
+by studying the temperature dependence of two-terminal InAs/GaSb
+heterojunctions, allowing for the true nature of tunneling at the interface to
+be seen without convolution from other three-terminal parasitic effects such as
+gate oxide traps. We compare the temperature dependence of peak current, excess
+current, and conductance slope for InAs/GaSb interfaces with and without
+interface defects. We identify that the tunnel and excess currents depend on
+temperature and defect density and propose that the ultimate leakage current in
+TFETs based on these materials will be affected by defects and inhomogeneity at
+the interface. We determine that the conductance slope, a two-terminal analog
+to subthreshold slope, does not depend on temperature, contrasting sharply with
+the heavy temperature dependence seen in three terminal devices in literature.
+We propose that TFETs based on this and similar materials systems are dominated
+by parasitic effects such as tunneling into oxide trap states, or other
+parasitics that are not intrinsic to the heterojunction itself, and that in the
+absence of these effects, the true steepness from band-to-band tunneling is
+limited by defects and inhomogeneity at the interface.",1503.02763v1
+2015-03-12,Evaluation of Radiation Dose Reduction during CT Scans Using Oxide Bismuth and Nano-Barium Sulfate Shields,"The purpose of the present study was to evaluate radiation dose reduction and
+image quality during CT scanning by using a new dose reduction fiber sheet
+(DRFS) with commercially available bismuth shields. These DRFS were composed of
+nano-barium sulfate (BaSO4), filling the gaps left by the large oxide bismuth
+(Bi2O3) particle sizes. The radiation dose was measured five times at
+directionss of 12 o'clock from the center of the polymethyl methacrylate (PMMA)
+head phantom to calculate an average value using a CT ionization chamber. The
+image quality measured CT transverse images of the PMMA head phantom depending
+on X-ray tube voltages and the type of shielding. Two regions of interest in CT
+transverse images were chosen from the right and left areas under the surface
+of the PMMA head phantom and from ion chamber holes located at directions of 12
+o'clock from the center of the PMMA head phantom. The results of this study
+showed that the new DRFS shields could reduce dosages to 15.61%, 23.05%, and
+22.71% more in 90 kVp, 120 kVp, and 140 kVp, respectively, than with a
+conventional bismuth shield of the same thickness, while maintaining image
+quality. In addition, the DRFS were produced to about 25% more thinness than
+conventional bismuth. We concluded, therefore, that DRFS can replace the
+conventional bismuth and may be utilized as a new shield.",1503.03702v1
+2015-03-26,Epsilon-Near-Zero Al-Doped ZnO for Ultrafast Switching at Telecom Wavelengths: Outpacing the Traditional Amplitude-Bandwidth Trade-Off,"Transparent conducting oxides have recently gained great attention as
+CMOS-compatible materials for applications in nanophotonics due to their low
+optical loss, metal-like behavior, versatile/tailorable optical properties, and
+established fabrication procedures. In particular, aluminum doped zinc oxide
+(AZO) is very attractive because its dielectric permittivity can be engineered
+over a broad range in the near infrared and infrared. However, despite all
+these beneficial features, the slow (> 100 ps) electron-hole recombination time
+typical of these compounds still represents a fundamental limitation impeding
+ultrafast optical modulation. Here we report the first epsilon-near-zero AZO
+thin films which simultaneously exhibit ultra-fast carrier dynamics (excitation
+and recombination time below 1 ps) and an outstanding reflectance modulation up
+to 40% for very low pump fluence levels (< 4 mJ/cm2) at the telecom wavelength
+of 1.3 {\mu}m. The unique properties of the demonstrated AZO thin films are the
+result of a low temperature fabrication procedure promoting oxygen vacancies
+and an ultra-high carrier concentration. As a proof-of-concept, an all-optical
+AZO-based plasmonic modulator achieving 3 dB modulation in 7.5 {\mu}m and
+operating at THz frequencies is numerically demonstrated. Our results overcome
+the traditional ""modulation depth vs. speed"" trade-off by at least an order of
+magnitude, placing AZO among the most promising compounds for
+tunable/switchable nanophotonics.",1503.07832v1
+2015-03-28,Epitaxial Phases of BiMnO$_3$ from First Principles,"Bulk BiMnO$_3$ is the only transition-metal perovskite oxide that is
+insulating and shows strong ferromagnetism. This distinctive behavior would
+make it a promising candidate as a magnetoelectric multiferroic if it was also
+a polar material, but experiments have shown that bulk BiMnO$_3$ has either a
+very small polarization (below 0.1~$\mu$C/cm$^2$) or, most likely, that it is a
+paraelectric. There is also experimental evidence that the polarization in
+BiMnO$_3$ {\em films} grown on SrTiO$_3$ can be as high as 20~$\mu$C/cm$^2$.
+Despite of the interest of these behaviors, the diagram of BiMnO$_3$ as a
+function of epitaxial strain has remained largely unexplored. In this article,
+we use first-principles to predict that both under enough compressive and
+tensile epitaxial strain BiMnO$_3$ films are ferroelectric with a giant
+polarization around 100~$\mu$C/cm$^2$. The phases displayed by the films are
+similar to those experimentally found for BiFeO$_3$ in similar conditions---at
+compressive strains, the film is supertetragonal with a large component of the
+polarization pointing out of plane, while at tensile strains the polarization
+points mostly in plane. Like in BiFeO$_3$ films, these phases are
+antiferromagnetic---the orbital ordering responsible for ferromagnetism in
+BiMnO$_3$ is absent in the polar phases. Our calculations also show that the
+band gap of some of these BiMnO$_3$ films is substantially smaller than gaps
+typically found in ferroelectric oxides, suggesting it may be a suitable
+material for photovoltaic applications.",1503.08293v1
+2015-04-01,Chemical modifications and stability of phosphorene with impurities: A first principles study,"We perform a systematic first-principles study of phosphorene in the presence
+of typical monovalent (hydrogen, fluorine) and divalent (oxygen) impurities.
+The results of our modeling suggest a decomposition of phosphorene into weakly
+bonded one-dimensional (1D) chains upon single- and double-side hydrogenation
+and fluorination. In spite of a sizable quasiparticle band gap (2.29 eV), fully
+hydrogenated phosphorene found to be dynamically unstable. In contrast, full
+fluorination of phosphorene gives rise to a stable structure, being an indirect
+gap semiconductor with the band gap of 2.27 eV. We also show that fluorination
+of phosphorene from the gas phase is significantly more likely than
+hydrogenation due to the relatively low energy barrier for the dissociative
+adsorption of F2 (0.19 eV) compared to H2 (2.54 eV). At low concentrations,
+monovalent impurities tend to form regular atomic rows phosphorene, though such
+patterns do not seem to be easily achievable due to high migration barriers
+(1.09 and 2.81 eV for H2 and F2, respectively). Oxidation of phosphorene is
+shown to be a qualitatively different process. Particularly, we observe
+instability of phosphorene upon oxidation, leading to the formation of
+disordered amorphous-like structures at high concentrations of impurities.",1504.00124v2
+2015-04-21,Mechanisms and Geochemical Models of Core Formation,"The formation of the Earth's core is a consequence of planetary accretion and
+processes in the Earth's interior. The mechanical process of planetary
+differentiation is likely to occur in large, if not global, magma oceans
+created by the collisions of planetary embryos. Metal-silicate segregation in
+magma oceans occurs rapidly and efficiently unlike grain scale percolation
+according to laboratory experiments and calculations. Geochemical models of the
+core formation process as planetary accretion proceeds are becoming
+increasingly realistic. Single stage and continuous core formation models have
+evolved into multi-stage models that are couple to the output of dynamical
+models of the giant impact phase of planet formation. The models that are most
+successful in matching the chemical composition of the Earth's mantle, based on
+experimentally-derived element partition coefficients, show that the
+temperature and pressure of metal-silicate equilibration must increase as a
+function of time and mass accreted and so must the oxygen fugacity of the
+equilibrating material. The latter can occur if silicon partitions into the
+core and through the late delivery of oxidized material. Coupled dynamical
+accretion and multi-stage core formation models predict the evolving mantle and
+core compositions of all the terrestrial planets simultaneously and also place
+strong constraints on the bulk compositions and oxidation states of primitive
+bodies in the protoplanetary disk.",1504.05417v1
+2015-04-28,Transboundary Secondary Organic Aerosol in Western Japan: An Observed Limitation of the f44 Oxidation Indicator,"To obtain evidence for secondary organic aerosol formation during the long
+range transport of air masses over the East China Sea, we conducted field
+measurements in March 2012 at the Fukue atmospheric monitoring station,
+Nagasaki, in western Japan. The relative abundance of m/z 44 in fine organic
+aerosol mass spectra (f44) was measured by an Aerodyne aerosol chemical
+speciation monitor. The stable carbon isotope ratio (d13C) of low volatile
+water soluble organic carbon (LV-WSOC) in the daily filter samples of total
+suspended particulate matter was also analyzed using an elemental analyzer
+coupled with an isotope ratio mass spectrometer. Additionally, in situ
+measurements of NOx and NOy were performed using NOx and NOy analyzers. The
+measurements showed that, unlike the systematic trends observed in a previous
+field study, a scatter plot for d13C of LV-WSOC versus f44 indicated a random
+variation. Comparison of f44 with the photochemical age estimated by the NOx to
+NOy ratio revealed that the f44 values distributing around 0.2 likely reached a
+saturation level already and the f44 values were significantly lower than the
+observed f44, approximately 0.3, at Hedo in the previous study. These findings
+imply that the saturation point of f44, and the use of f44 as an oxidation
+indicator, is case dependent.",1504.07400v1
+2015-05-02,Electronic Structure of Oxide Interfaces: A Comparative Analysis of GdTiO$_3$/SrTiO$_3$ and LaAlO$_3$/SrTiO$_3$ Interfaces,"Emergent phases in the two-dimensional electron gas (2DEG) formed at the
+interface between two insulating oxides have attracted great attention in the
+past decade. We present ab-initio electronic structure calculations for the
+interface between a Mott insulator GdTiO$_3$ (GTO) and a band insulator
+SrTiO$_3$ (STO) and compare our results with those for the widely studied
+LaAlO$_3$/SrTiO$_3$ (LAO/STO) interface between two band insulators. Our
+GTO/STO results are in excellent agreement with experiments, but qualitatively
+different from LAO/STO. We find an interface carrier density of 0.5$e^{-}$/Ti,
+independent of GTO thickness in both superlattice and thin film geometries, in
+contrast to LAO/STO. The superlattice geometry in LAO/STO offers qualitatively
+the same result as in GTO/STO. On the other hand, for a thin film geometry, the
+interface carrier density builds up only beyond a threshold thickness of LAO.
+The positive charge at the vacuum surface that compensates the 2DEG at the
+interface also exhibits distinct behaviors in the two systems. The top GTO
+layer is found to be insulating due to correlation-driven charge
+disproportionation, while the top LAO layer is metallic within band theory and
+may become insulating due to surface disorder or surface reconstruction.",1505.00339v2
+2015-05-16,Non-Arrhenius conduction due to the interface-trap-induced disorder in X-doped amorphous InXZnO thin-film transistors,"Thin film transistors, with channels composed of In-X-Zn oxides, IXZO, with X
+dopants: Ga, Sb, Be, Mg, Ag, Ca, Al, Ni, and Cu, were fabricated and their I-V
+characteristics were taken at selected temperatures in the 77K<T<300K range.
+The low field mobility, mu, and the interface defect density, Nst were
+extracted from the characteristics for each of the studied IXZOs. At higher T
+the mobility follows the Arrhenius law with an upward distortion, increasing as
+T was lowered, gradually transforming into the exp [-(T0/T)1/4] variation. We
+showed that mu(T, Nst) follows mu0exp[-Eaeff(T,Nst)/kT], with T-dependent
+effective activation energy Eaeff(T, Nst) accounts for the data, revealing a
+linear correlation between Eaeff and Nst at higher T. Temperature variation of
+Eaeff(T, Nst) was evaluated using a model assuming a random distribution of
+conduction mobility edge Ec values in the oxides, stemming from spatial
+fluctuations induced by disorder in the interface traps distribution. For a
+Gaussian distribution of Ec, the activation energy Eaeff(T, Nst) varies
+linearly with 1/T, which accounts satisfactorily for the data obtained on all
+the studied IXZOs. The model also shows that Eaeff(T, Nst) is a linear function
+of Nst at a fixed T, which explains the exponential decrease of mu with NST.",1505.04291v1
+2015-05-20,Self-Adaptive Spike-Time-Dependent Plasticity of Metal-Oxide Memristors,"Metal-oxide memristors have emerged as promising candidates for hardware
+implementation of artificial synapses - the key components of high-performance,
+analog neuromorphic networks - due to their excellent scaling prospects. Since
+some advanced cognitive tasks require spiking neuromorphic networks, which
+explicitly model individual neural pulses (spikes) in biological neural
+systems, it is crucial for memristive synapses to support the
+spike-time-dependent plasticity (STDP), which is believed to be the primary
+mechanism of Hebbian adaptation. A major challenge for the STDP implementation
+is that, in contrast to some simplistic models of the plasticity, the
+elementary change of a synaptic weight in an artificial hardware synapse
+depends not only on the pre-synaptic and post-synaptic signals, but also on the
+initial weight (memristor's conductance) value. Here we experimentally
+demonstrate, for the first time, STDP protocols that ensure self-adaptation of
+the average memristor conductance, making the plasticity stable, i.e.
+insensitive to the initial state of the devices. The experiments have been
+carried out with 200-nm Al2O3/TiO2-x memristors integrated into 12x12
+crossbars. The experimentally observed self-adaptive STDP behavior has been
+complemented with numerical modeling of weight dynamics in a simple system with
+a leaky-integrate-and-fire neuron with a random spike-train input, using a
+compact model of memristor plasticity, fitted for quantitatively correct
+description of our memristors.",1505.05549v1
+2015-06-11,Direct Imaging of Nanoscale Conductance Evolution in Ion-Gel-Gated Oxide Transistors,"Electrostatic modification of functional materials by electrolytic gating has
+demonstrated a remarkably wide range of density modulation, a condition crucial
+for developing novel electronic phases in systems ranging from complex oxides
+to layered chalcogenides. Yet little is known microscopically when carriers are
+modulated in electrolyte-gated electric double-layer transistors (EDLTs) due to
+the technical challenge of imaging the buried electrolyte-semiconductor
+interface. Here, we demonstrate the real-space mapping of the channel
+conductance in ZnO EDLTs using a cryogenic microwave impedance microscope. A
+spin-coated ionic gel layer with typical thicknesses below 50 nm allows us to
+perform high resolution (on the order of 100 nm) sub-surface imaging, while
+maintaining the capability of inducing the metal-insulator transition under a
+gate bias. The microwave images vividly show the spatial evolution of channel
+conductance and its local fluctuations through the transition, as well as the
+uneven conductance distribution established by a large source-drain bias. The
+unique combination of ultra-thin ion-gel gating and microwave imaging offers a
+new opportunity to study the local transport and mesoscopic electronic
+properties in EDLTs.",1506.03785v1
+2015-07-17,4f fine-structure levels as the dominant error in the electronic structures of binary lanthanide oxides,"The ground-state 4f fine-structure levels in the intrinsic optical transition
+gaps between the 2p and 5d orbitals of lanthanide sesquioxides (Ln2O3,
+Ln=La...Lu) were calculated by a two-way crossover search for the U parameters
+for DFT+U calculations. The original 4f-shell potential perturbation in the
+linear response method were reformulated within the constraint volume of
+thegiven solids. The band structures were also calculated. This method yields
+nearly constant optical transition gaps between Ln-5d and O-2p orbitals, with
+magnitudes of 5.3~5.5 eV. This result verifies that the error in the band
+structure calculations for Ln2O3 is dominated by the inaccuracies in the
+predicted 4f levels in the 2p-5d transition gaps, which strongly and
+nonlinearly depend on the on-site Hubbard U. The relationship between the 4f
+occupancies and Hubbard U is non-monotonic and is entirely different from that
+for materials with 3d or 4d orbitals, such as transition metal oxides. This new
+linear response DFT+U method can provide a simpler understanding of the
+electronic structure of Ln2O3 and enables a quick examination of the electronic
+structures of lanthanide solids prior to hybrid functional or GW calculations.",1507.05088v3
+2015-07-23,Spatially resolved TiOx phases in RRAM conductive nanofilaments using soft X-ray spectromicroscopy,"Reduction in metal-oxide thin films has been suggested as the key mechanism
+responsible for forming conductive nanofilaments within solid-state memory
+devices, enabling their resistive switching capacity. The quantitative spatial
+identification of such filaments is a daunting task, particularly for
+metal-oxides capable of exhibiting multiple phases as in the case of TiOx.
+Here, we spatially resolve and chemically characterize distinct TiOx phases in
+localized regions of a TiOx-based memristive device by combining full-field
+transmission X-ray microscopy with soft X-ray spectroscopic analysis that is
+performed on lamella samples. We particularly show that electrically
+pre-switched devices in low-resistive states comprise reduced disordered phases
+with O/Ti ratios close to Ti2O3 stoichiometry that aggregate in a ~ 100 nm
+filamentary region electrically conducting the top and bottom electrodes of the
+devices. We have also identified crystalline rutile and orthorhombic-like TiO2
+phases in the region adjacent to the filament, suggesting that the temperature
+increases locally up to 1000 K, validating the role of Joule heating in
+resistive switching. Contrary to previous studies, our approach enables to
+simultaneously investigate morphological and chemical changes in a quantitative
+manner without incurring difficulties imposed by interpretation of electron
+diffraction patterns acquired via conventional electron microscopy techniques.",1507.06588v1
+2015-08-12,Electrical Control of Broadband Terahertz Wave Transmission with Two-Terminal Graphene Oxide Devices,"Carbon nanomaterials such as carbon nanotubes and graphene have proved to be
+efficient building blocks for active optoelectronic devices. Especially, the
+exotic properties of crystalline graphene, such as a linear/gapless energy
+dispersion, offer a generic route to the development of active photonic
+modulator at the infrared (IR) and terahertz (THz) regime with large modulation
+depth. Here, we show that graphene oxide (GO), an oxygenated derivative of
+graphene with randomly distributed molecular defects (e.g., adsorbed water
+molecules and punched holes), can provide a different way to effectively
+control broadband THz transmission amplitude, when incorporated into
+two-terminal electrode devices. Electrically trapped charge carriers within
+localized impurity states (LIS) of GO, which originate from fully randomized
+defective structure of GO, results in a large modulation of transmission
+amplitude (~30%) for broadband THz waves (0.3 ~ 2.0 THz) even at room
+temperature. Interesting hysteretic behavior observed in the control of
+broadband THz transmission further confirms the key role of trapped charge
+carriers in switching of broadband THz waves. The device architecture
+constructed by simple solution printing of GO onto the two-terminal electrode
+enables easy-to-implement active photonic devices.",1508.02813v1
+2015-08-26,Tuning the electronic properties at the surface of BaBiO3 thin films,"The presence of 2D electron gases at surfaces or interfaces in oxide thin
+films remains a hot topic in condensed matter physics. In particular, BaBiO3
+appears as a very interesting system as it was theoretically proposed that its
+(001) surface should become metallic if a Bi-termination is achieved (Vildosola
+et al., PRL 110, 206805 (2013)). Here we report on the preparation by pulsed
+laser deposition and characterization of BaBiO3 thin films on silicon. We show
+that the texture of the films can be tuned by controlling the growth
+conditions, being possible to stabilize strongly (100)-textured films. We find
+significant differences on the spectroscopic and transport properties between
+(100)-textured and non-textured films. We rationalize these experimental
+results by performing first principles calculations, which indicate the
+existence of electron doping at the (100) surface. This stabilizes Bi ions in a
+3+ state, shortens Bi-O bonds and reduces the electronic band gap, increasing
+the surface conductivity. Our results emphasize the importance of surface
+effects on the electronic properties of perovskites, and provide strategies to
+design novel oxide heterostructures with potential interface-related 2D
+electron gases.",1508.06480v4
+2015-08-28,Quantifying electronic correlation strength in a complex oxide: a combined DMFT and ARPES study of LaNiO$_3$,"The electronic correlation strength is a basic quantity that characterizes
+the physical properties of materials such as transition metal oxides.
+Determining correlation strengths requires both precise definitions and a
+careful comparison between experiment and theory. In this paper we define the
+correlation strength via the magnitude of the electron self-energy near the
+Fermi level. For the case of LaNiO$_3$, we obtain both the experimental and
+theoretical mass enhancements $m^\star/m$ by considering high resolution
+angle-resolved photoemission spectroscopy (ARPES) measurements and density
+functional + dynamical mean field theory (DFT + DMFT) calculations. We use
+valence-band photoemission data to constrain the free parameters in the theory,
+and demonstrate a quantitative agreement between the experiment and theory when
+both the realistic crystal structure and strong electronic correlations are
+taken into account. These results provide a benchmark for the accuracy of the
+DFT+DMFT theoretical approach, and can serve as a test case when considering
+other complex materials. By establishing the level of accuracy of the theory,
+this work also will enable better quantitative predictions when engineering new
+emergent properties in nickelate heterostructures.",1508.07247v2
+2015-09-08,Two-dimensional TiOx nanostructures on Au(111): a Scanning Tunneling Microscopy and Spectroscopy investigation,"We investigated the growth of titanium oxide two-dimensional (2D)
+nanostructures on Au(111), produced by Ti evaporation and post-deposition
+oxidation. Scanning tunneling microscopy and spectroscopy (STM and STS) and
+low-energy electron diffraction (LEED) measurements characterized the
+morphological, structural and electronic properties of the observed structures.
+Five distinct TiO\sub{x} phases were identified: the \emph{honeycomb} and
+\emph{pinwheel} phases appear as monolayer films wetting the gold surface,
+while nanocrystallites of the \emph{triangular}, \emph{row} and \emph{needle}
+phases grow mainly over the honeycomb or pinwheel layers. Density Functional
+Theory (DFT) investigation of the honeycomb structure supports a $(2\times 2)$
+structural model based on a Ti-O bilayer having $\text{Ti}_2\text{O}_3$
+stoichiometry. The pinwheel phase was observed to evolve, for increasing
+coverage, from single triangular crystallites to a well-ordered film forming a
+$(4\sqrt{7}\times 4\sqrt{7})R19.1^\circ$ superstructure, which can be
+interpreted within a moir\~A\c{opyright}-like model. Structural characteristics
+of the other three phases were disclosed from the analysis of high-resolution
+STM measurements. STS measurements revealed a partial metallization of
+honeycomb and pinwheel and a semiconducting character of row and triangular
+phases.",1509.02363v1
+2015-09-05,Towards rational design of catalysts supported on a topological insulator substrate,"Exotic and robust metallic surface states of topological insulators (TIs)
+have been expected to provide a promising platform for novel surface chemistry
+and catalysis. However, it is still an unprecedented field how TIs affect the
+activity of catalysts. In this work, we study the effects of topological
+surface states (TSSs) on the activity of transition metal clusters (Au, Ag, Cu,
+Pt, and Pd), which are supported on a TI Bi2Se3 substrate. It was found the
+adsorption energy of oxygen on the supported catalysts can be always enhanced
+due to the TSSs. However, it does not necessarily mean an increase of the
+activity in catalytic oxidation reaction. Rather, the enhanced adsorption
+behavior in the presence of TSSs exhibits dual effects, determined by the
+intrinsic reactivity of these catalysts with oxygen. For the Au case, the
+activity of catalytic oxidation can be improved because the intrinsic binding
+between Au and O is relatively weak. In contrast, a negative effect is found
+for the Pt and Pd clusters since the intrinsic binding of Pt and Pd with oxygen
+is too strong. We also found that the effect of TSSs on the activity of
+hydrogen evolution reaction (HER) is quite similar, i.e. the metals with
+original weak reactivity can gain a positive effect from TSSs. The present work
+can pave a way for more rational design and selection of catalysts when using
+TIs as substrates.",1509.02484v1
+2015-09-09,Crystal Structure and Electronic Properties of Bulk and Thin Film Brownmillerite Oxides,"The equilibrium structure and functional properties exhibited by
+brownmillerite oxides, a family of perovskite-derived structures with
+alternating layers of $B$O$_6$ octahedra and $B$O$_4$ tetrahedra, viz., ordered
+arrangements of oxygen vacancies, is dependent on a variety of competing
+crystal-chemistry factors. We use electronic structure calculations to
+disentangle the complex interactions in two ferrates, Sr$_2$Fe$_2$O$_5$ and
+Ca$_2$Fe$_2$O$_5$, relating the stability of the equilibrium (strain-free) and
+thin film structures to both previously identified and newly herein proposed
+descriptors. We show that cation size and intralayer separation of the
+tetrahedral chains provide key contributions to the preferred ground state. We
+show the bulk ground state structure is retained in the ferrates over a range
+of strain values; however, a change in the orientation of the tetrahedral
+chains, i.e., a perpendicular orientation of the vacancies relative to the
+substrate, is stabilized in the compressive region. The structure stability
+under strain is largely governed by maximizing the intraplane separation of the
+`dipoles' generated from rotations of the FeO$_4$ tetrahedra. Lastly, we find
+that the electronic band gap is strongly influenced by strain, manifesting as
+an unanticipated asymmetric-vacancy alignment dependent response. This
+atomistic understanding establishes a practical route for the design of novel
+functional electronic materials in thin film geometries.",1509.02593v1
+2015-09-10,Resonant x-ray scattering studies of charge order in cuprates,"X-ray techniques have been used for more than a century to study the atomic
+and electronic structure in virtually any type of material. The advent of
+correlated electron systems, in particular complex oxides, brought about new
+scientific challenges and opportunities for the advancement of conventional
+x-ray methods. In this context, the need for new approaches capable of
+selectively sensing new forms of orders involving all degrees of freedom --
+charge, orbital, spin, and lattice -- paved the way for the emergence and
+success of resonant x-ray scattering, which has become an increasingly popular
+and powerful tool for the study of electronic ordering phenomena in solids.
+Here we review the recent resonant x-ray scattering breakthroughs in the copper
+oxide high-temperature superconductors, in particular regarding the phenomenon
+of charge order -- a broken-symmetry state occurring when valence electrons
+self-organize into periodic structures. After a brief historical perspective on
+charge order, we outline the milestones in the development of resonant x-ray
+scattering, as well as the basic theoretical formalism underlying its unique
+capabilities. The rest of the review will focus on the recent contributions of
+resonant scattering to the tremendous advancements in our description and
+understanding of charge order. To conclude, we propose a series of present and
+upcoming challenges, and discuss the future outlook for this technique.",1509.03313v1
+2015-09-15,Characterization and Dielectric Properties of Microwave Rare Earth Ceramics Materials for Telecommunications,"The rare-earth-metal-oxide based electronic materials were produced via a
+conventional mixed-oxide route. Thermal analysis, XRD and SEM were used to
+follow phase evolution and demonstrate the phase purity. Analytical TEM were
+used to analyze crystal structural defects and to track the presence of
+secondary phases, especially at grain boundaries. A crystal structure
+determination was also performed. Phonon modes were analyzed with FTIR and
+Raman spectroscopies and correlated with the origin of dielectric permittivity
+({\epsilon}r) and radiation losses (tan {\delta}) characteristics. In some
+compound and mixed compound Raman band mode exist, but this band is absent in
+simple perovskite indicating that this band is associated with distribution of
+B-site cations ordering. Some of compound shows long range order in B-site,
+while it does not present in other material. A photo-acoustic sampling
+technique in conjunction with the FTIR spectroscopy was employed, allowing the
+analysis of neat materials with minimal sample preparation. Measurements of the
+quality factor (Qf), {\epsilon}r and the temperature coefficient of the
+resonant frequency ({\tau}f) characteristics were made at the microwave
+resonant frequency using a vector or network analyzer.
+  These perovskite have low tolerance factor because of considerable size
+misfit of constituting atoms. For determination of atomic size and
+characterization of constitution atoms, the test of samples and Rietveld
+refinement using GSAS programs were used to do this examination. These
+materials have attractive dielectric properties are being evaluated extensively
+for substrates for multi-chip-module (MCM) devices and microwave
+telecommunications.",1509.04445v2
+2015-09-18,Effect of Strain on Ferroelectric Field Effect in Strongly Correlated Oxide Sm$_{0.5}$Nd$_{0.5}$NiO$_3$,"We report the effect of epitaxial strain on the magnitude and retention of
+the ferroelectric field effect in high quality PbZr$_{0.3}$Ti$_{0.7}$O$_3$
+(PZT)/3.8-4.3 nm Sm$_{0.5}$Nd$_{0.5}$NiO$_3$ (SNNO) heterostructures grown on
+(001) LaAlO$_3$ (LAO) and SrTiO$_3$ (STO) substrates. For SNNO on LAO, which
+exhibits a first-order metal-insulator transition (MIT), switching the
+polarization of PZT induces a 10 K shift in the transition temperature
+$T_{MI}$, with a maximum resistance change between the on and off states of
+$\Delta$$R$/$R_{on}$ ~75%. In sharp contrast, only up to 5% resistance change
+has been induced in SNNO on STO, where the MIT is second-order, with the
+modulation of $T_{MI}$ negligibly small. We also observe thermally activated
+retention of the off state resistance $R_{off}$ in both systems, with the
+activation energy of 22 meV (28 meV) for devices on LAO (STO). The time
+dynamics and thermal response of the field effect instability points to
+phonon-assisted interfacical trapping of charged mobile defects, which are
+attributed to strain induced oxygen vacancies. At room temperature, $R_{off}$
+stabilizes at ~55% and ~19% of the initial switching levels for SNNO on LAO and
+STO, respectively, reflecting the significantly different oxygen vacancy
+densities in these two systems. Our results reveal the critical role of strain
+in engineering and modeling the complex oxide composite structures for
+nanoelectronic and spintronic applications.",1509.05493v2
+2015-09-28,Nitride Multilayers as a Platform for Parallel Two-Dimensional Electron-Hole Gases: MgO/ScN(111),"At interfaces between insulating oxides LaAlO$_3$ and SrTiO$_3$, a two
+dimensional electron gas (2DEG) has been observed and well studied, while the
+predicted hole gas (2DHG) has not been realized due to the strong tendency of
+holes in oxygen $2p$ orbitals to localize. Here we propose, via ab initio
+calculations, an unexplored class of materials for the realization of parallel
+two dimensional (2D), two carrier (electron+hole) gases: nitride-oxide
+heterostructures, with (111)-oriented ScN and MgO as the specific example.
+Beyond a critical thickness of five ScN layers, this interface hosts spatially
+separated conducting Sc-$3d$ electrons and N-$2p$ holes, each confined to
+$\sim$two atomic layers -- the transition metal nitride provides both gases. A
+guiding concept is that the N$^{3-}$ anion should promote robust two carrier 2D
+hole conduction compared to that of O$^{2-}$; metal mononitrides are mostly
+metallic and even superconducting while most metal monoxides are insulating. A
+second positive factor is that the density of transition metal ions, hence of a
+resulting 2DG, is about three times larger for a rocksalt (111) interface than
+for a perovskite(001) interface. Our results, including calculation of Hall
+coefficient and thermopower for each conducting layer separately, provide
+guidance for new exploration, both experimental and theoretical, on
+nitride-based conducting gases that should promote study of long sought exotic
+states viz. new excitonic phases and distinct, nanoscale parallel
+superconducting nanolayers.",1509.08518v2
+2015-10-11,Prediction of novel stable compounds in the Mg-Si-O system under exoplanet pressures,"The Mg-Si-O system is the major Earth and rocky planet-forming system. Here,
+through quantum variable-composition evolutionary structure explorations, we
+have discovered several unexpected stable binary and ternary compounds in the
+Mg-Si-O system. Besides the well-known SiO2 phases, we have found two
+extraordinary silicon oxides, SiO3 and SiO, which become stable at pressures
+above 0.51 TPa and 1.89 TPa, respectively. In the Mg-O system, we have found
+one new compound, MgO3, which becomes stable at 0.89 TPa. We find that not only
+the (MgO)x(SiO2)y compounds, but also two (MgO3)x(SiO3)y compounds, MgSi3O12
+and MgSiO6, have stability fields above 2.41 TPa and 2.95 TPa, respectively.
+The highly oxidized MgSi3O12 can form in deep mantles of mega-Earths with
+masses above 20 M+ (M+:Earth's mass). Furthermore, the dissociation pathways of
+pPv-MgSiO3 are also clarified, and found to be different at low and high
+temperatures. The low-temperature pathway is MgSiO3 -> Mg2SiO4 + MgSi2O5 ->
+SiO2 + Mg2SiO4 -> MgO + SiO2, while the high-temperature pathway is MgSiO3 ->
+Mg2SiO4 + MgSi2O5 -> MgO + MgSi2O5 -> MgO + SiO2. Present results are relevant
+for models of the internal structure of giant exoplanets, and for understanding
+the high-pressure behavior of materials.",1510.03061v1
+2015-10-13,Instability and Surface Potential Modulation of Self-Patterned (001)SrTiO3 Surfaces,"The (001)SrTiO3 crystal surface can be engineered to display a self-organized
+pattern of well-separated and nearly pure single-terminated SrO and TiO2
+regions by high temperature annealing in oxidizing atmosphere. By using surface
+sensitive techniques we have obtained evidence of such surface chemical
+self-structuration in as-prepared crystals and unambiguously identified the
+local composition. The contact surface potential at regions initially
+consisting of majority single terminations (SrO and TiO2) is determined to be
+smaller for SrO than for TiO2, in agreement with theoretical predictions,
+although the measured difference below 100 meV is definitely smaller than
+theoretical predictions for ideally pure single-terminated SrO and TiO2
+surfaces. These relative values are maintained if samples are annealed in UHV
+up to 200 degrees Celsius. Annealing in UHV at higher temperature (400 degrees
+Celsius) preserves the surface morphology of self-assembled TiO2 and SrO rich
+regions, although a non-negligible chemical intermixing is observed. The most
+dramatic consequence is that the surface potential is reversed. It thus follows
+that electronic and chemical properties of (001)SrTiO3, widely used in oxide
+thin films growth, can largely vary before growth starts in a manner strongly
+dependent on temperature and pressure conditions.",1510.03631v1
+2015-10-28,Systematics in the metal-insulator transition temperatures in vanadium oxides,"Nine of the known vanadium oxides, VO$_{2-1/n}$ (n - a positive or negative
+integer) with n=2 - 6, 8, 9, $\infty$ and -6, undergo metal-insulator
+transitions accompanied by structural transitions, at various temperatures
+T$_{MIT}$ (V$_7$O$_{13}$ is metallic above T=0). Among the persistent efforts
+to determine the driving force(s) of these transitions, electron-electron
+(Mott-like) and electron-phonon (Peierls-like) interactions, there were several
+attempts to find systematics in T$_{MIT}$ as function of n. Here we present an
+unexpectedly simple and illuminating systematics that holds for positive n: if
+T$_{MIT}$ is the absolute value of the difference between T$_M$(n) and
+T$_P$(n), which represent the contributions of electron-electron and
+electron-phonon interactions, respectively, all data points of T$_M$-T$_P$
+versus 1/n lie on, or close to, two simple straight lines; one is T$_M$-T$_P$=
+T$_{\infty}$(7/n-1) for V$_3$O$_5$, V$_4$O$_7$, V$_5$O$_9$, V$_7$O$_{13}$,
+V$_8$O$_{15}$, V$_9$O$_{17}$ and VO$_2$ and the other is T$_M$-T$_P$=
+T$_{\infty}$(3/n-1) for V$_2$O$_3$, V$_6$O$_{11}$ and VO$_2$.",1510.08286v1
+2015-10-30,Ab initio study of the ferroelectric strain dependence and 180$^\circ$ domain walls in the barium metal fluorides BaMgF$_4$ and BaZnF$_4$,"We investigate the strain dependence of the ferroelectric polarization and
+the structure of the ferroelectric domain walls in the layered
+perovskite-related barium fluorides, BaMF$_4$ (M=Mg, Zn). The unusual
+""geometric ferroelectricity"" in these materials is driven by the softening of a
+single polar phonon mode consisting of rotations of the MF$_6$ octahedra
+accompanied by polar displacements of the Ba cations, and in contrast to
+conventional ferroelectrics involves minimal electronic rehybridization. We
+therefore anticipate a different strain dependence of the polarization, and
+alternative domain wall structures compared with those found in conventional
+ferroelectric materials. Using first-principles calculations based on density
+functional theory (DFT) within the general gradient approximation (GGA), we
+calculate the variation of the crystal structure and the ferroelectric
+polarization under both compressive and tensile strain. We perform structural
+relaxations of neutral domain walls between oppositely oriented directions of
+the ferroelectric polarization and calculate their corresponding energies to
+determine which are most likely to form. We compare our results to literature
+values for conventional perovskite oxides to provide a source of comparison for
+understanding the ferroelectric properties of alternative non-oxide materials
+such as the barium fluorides.",1510.09181v2
+2015-11-27,Effect of interface geometry on electron tunnelling in Al/Al$_2$O$_3$/Al junctions,"We investigate how different interface geometries of an Al/Al$_2$O$_3$
+junction, a common component of modern tunnel devices, affect electron
+transport through the tunnel barrier. We study six distinct Al/Al$_2$O$_3$
+interfaces which differ in stacking sequences of the metal and the oxide
+surface atoms and the oxide termination. To construct model potential barrier
+profiles for each examined geometry, we rely on first-principles
+density-functional theory (DFT) calculations for the barrier heights and the
+shapes of the interface regions as well as on experimental data for the barrier
+widths. We show that even tiny variations in the atomic arrangement at the
+interface cause significant changes in the tunnel barrier parameters and,
+consequently, in electron transport properties. Especially, we obtain that
+variations in the crucial barrier heights and widths can be as large as 2 eV
+and 5 \AA, respectively. Finally, to gain information about the average
+properties of the measured junction, we fit the conductance calculated within
+the WKB approximation to the experimental data and interpret the fit parameters
+with the help of the DFT results.",1511.08636v1
+2015-11-30,Degradation of Black Phosphorus (BP): The Role of Oxygen and Water,"Black phosphorus (BP) has attracted significant interest as a monolayer or
+few-layer material with extraordinary electrical and optoelectronic properties.
+However, degradation in air and other environments is an unresolved issue that
+may limit future applications. In particular the role of different ambient
+species has remained controversial. Here, we report systematic experiments
+combined with ab-initio calculations that address the effects of oxygen and
+water in the degradation of BP. Our results show that BP rapidly degrades
+whenever oxygen is present, but is unaffected by deaerated (i.e., O2 depleted)
+water. This behavior is rationalized by oxidation involving a facile
+dissociative chemisorption of O2, whereas H2O molecules are weakly physisorbed
+and do not dissociate on the BP surface. Oxidation (by O2) turns the
+hydrophobic pristine BP surface progressively hydrophilic. Our results have
+implications on the development of encapsulation strategies for BP, and open
+new avenues for exploration of phenomena in aqueous solutions including
+solution-gating, electrochemistry, and solution-phase approaches for
+exfoliation, dispersion, and delivery of BP.",1511.09201v2
+2015-11-30,Simultaneous observation of small- and large-energy-transfer electron-electron scattering in three dimensional indium oxide thick films,"In three dimensional (3D) disordered metals, the electron-phonon
+(\emph{e}-ph) scattering is the sole significant inelastic process. Thus the
+theoretical predication concerning the electron-electron (\emph{e}-\emph{e})
+scattering rate $1/\tau_\varphi$ as a function of temperature $T$ in 3D
+disordered metal has not been fully tested thus far, though it was proposed 40
+years ago [A. Schmid, Z. Phys. \textbf{271}, 251 (1974)]. We report here the
+simultaneous observation of small- and large-energy-transfer \emph{e}-\emph{e}
+scattering in 3D indium oxide thick films. In temperature region of
+$T\gtrsim100$\,K, the temperature dependence of resistivities curves of the
+films obey Bloch-Gr\""{u}neisen law, indicating the films possess degenerate
+semiconductor characteristics in electrical transport property. In the low
+temperature regime, $1/\tau_\varphi$ as a function of $T$ for each film can not
+be ascribed to \emph{e}-ph scattering. To quantitatively describe the
+temperature behavior of $1/\tau_\varphi$, both the 3D small- and
+large-energy-transfer \emph{e}-\emph{e} scattering processes should be
+considered (The small- and large-energy-transfer \emph{e}-\emph{e} scattering
+rates are proportional to $T^{3/2}$ and $T^2$, respectively). In addition, the
+experimental prefactors of $T^{3/2}$ and $T^{2}$ are proportional to
+$k_F^{-5/2}\ell^{-3/2}$ and $E_F^{-1}$ ($k_F$ is the Fermi wave number, $\ell$
+is the electron elastic mean free path, and $E_F$ is the Fermi energy),
+respectively, which are completely consistent with the theoretical
+predications. Our experimental results fully demonstrate the validity of
+theoretical predications concerning both small- and large-energy-transfer
+\emph{e}-\emph{e} scattering rates.",1511.09269v1
+2015-11-26,Gate-tunable conducting oxide metasurfaces,"Metasurfaces composed of planar arrays of sub-wavelength artificial
+structures show promise for extraordinary light manipulation; they have yielded
+novel ultrathin optical components such as flat lenses, wave plates,
+holographic surfaces and orbital angular momentum manipulation and detection
+over a broad range of electromagnetic spectrum. However the optical properties
+of metasurfaces developed to date do not allow for versatile tunability of
+reflected or transmitted wave amplitude and phase after fabrication, thus
+limiting their use in a wide range of applications. Here, we experimentally
+demonstrate a gate-tunable metasurface that enables dynamic electrical control
+of the phase and amplitude of the plane wave reflected from the metasurface.
+Tunability arises from field-effect modulation of the complex refractive index
+of conducting oxide layers incorporated into metasurface antenna elements which
+are configured in a reflectarray geometry. We measure a phase shift of {\pi}
+and ~ 30% change in the reflectance by applying 2.5 V gate bias. Additionally,
+we demonstrate modulation at frequencies exceeding 10 MHz, and electrical
+switching of +/-1 order diffracted beams by electrical control over subgroups
+of metasurface elements, a basic requirement for electrically tunable
+beam-steering phased array metasurfaces. The proposed tunable metasurface
+design with high optical quality and high speed dynamic phase modulation
+suggests applications in next generation ultrathin optical components for
+imaging and sensing technologies, such as reconfigurable beam steering devices,
+dynamic holograms, tunable ultrathin lens, nano-projectors, and nanoscale
+spatial light modulators. Importantly, our design allows complete integration
+with electronics and hence electrical addressability of individual metasurface
+elements.",1511.09380v1
+2016-01-06,Observation of quantum Hall plateau-plateau transition and scaling behavior of the zeroth Landau level in graphene p-n-p junctions,"We report distinctive magnetotransport properties of a graphene p-n-p
+junction prepared by controlled diffusion of metallic contacts. In most cases,
+materials deposited on a graphene surface introduce substantial carrier
+scattering, which greatly reduces the high mobility of intrinsic graphene.
+However, we show that an oxide layer only weakly perturbs the carrier
+transport, which enables fabrication of a high-quality graphene p-n-p junction
+through a one-step and resist-free method. The measured conductance-gate
+voltage $(G-V_G)$ curves can be well described by a metal contact model, which
+confirms the charge density depinning due to the oxide layer. The graphene
+p-n-p junction samples exhibit pronounced quantum Hall effect, a well-defined
+transition point of the zeroth Landau level (LL), and scaling behavior. The
+scaling exponent obtained from the evolution of the zeroth LL width as a
+function of temperature exhibits a relatively low value of
+$\kappa=0.21\pm0.01$. Moreover, we calculate the energy level for the LLs based
+on the distribution of plateau-plateau transition points, further validating
+the assignment of the LL index of the QH plateau-plateau transition.",1601.01155v1
+2016-01-11,Compositions in YBa2Cu3Oy for 3-D bond order superconductors,"Self-doping in YBa2Cu3Oy starts to switch from a charge balancing of chain
+metal reduction and plane oxidation to one of chain ligand oxidation (O-) and
+plane reduction on quenching from >600K. Amongst the responses are plane
+expansions and types of unusually strong superconductivity such as elevated
+temperature superconductivity (ETS), observed through laser pulsing (Tc=552K*)
+and upon shot quenching (Tc=200K*). We ascribe ETS to limited 3-D
+superconductivity due to a correlated system of bond ordering within
+chain-plane sandwiches and propose how to stabilize it. Accordingly, plane
+expanding n-doping arises from self-doping charge equilibration with local
+chain Cu of two-fold O coordination (2). The dumbbell type bonds of both apical
+O- are a result of high-energy environment and comparable in their metric with
+electron pairs on the plane. Following empirical Tc=%(2)x11 we suggest
+increasing %(2) to cause the observed retrograde rise in Tc (photo-induced
+reflectivity edge) to a theoretical limit of Tc=1100K* at 100%(2). We propose
+compositions and heat treatments based on charge-lattice commensurability.
+Paired charge concentrations on planes, determined by bond ordering based on
+magic number counts, suggest several promising candidates such as
+c=0.22=2/3a0x3b0, c=0.17=2/3x4 or c=0.080=2/5x5. The latter could be achieved
+with 32%(2) and display Tc=352K* not only in laser pulsed but in shot quenched
+materials.",1601.02668v1
+2016-01-19,Partial Oxidation of Methane on a Nickel Catalyst: Kinetic Monte-Carlo Simulation Study,"Kinetic Monte-Carlo simulation is applied to study the partial oxidation of
+methane over a nickel catalyst. Based on the Langmuir-Hinshelwood mechanism,
+the kinetic behavior of this reaction is analyzed and the results are compared
+with previous experiments. This system exhibits kinetic phase transitions
+between reactive regions with sustained reaction and poisoned regions without
+reaction. The fractional coverages of the adsorbed species and the production
+rates of H2, CO, H2O, and CO2 are evaluated at steady state as functions of
+feed concentration of the methane and oxygen, and reaction temperature. The
+influence of lattice coordination number, diffusion, and impurities on the
+surface is investigated. The simulation results are in good agreement with the
+experimental studies where such results are available. It is observed that when
+the lattice coordination number is increased to eight, the width of the
+reactive region increases significantly. Moreover, the phase transition becomes
+continuous. The diffusion of adsorbed O and H on the surface plays a measurable
+role in the reaction, increasing the maximum production rates as the diffusion
+rate increases. In systems with impurities, the production rates are greatly
+reduced and the phase transition is also changed from being abrupt to
+continuous.",1601.05064v1
+2016-02-08,Clouds in Super-Earth Atmospheres: Chemical Equilibrium Calculations,"Recent studies have unequivocally proven the existence of clouds in
+super-Earth atmospheres (Kreidberg et al. 2014). Here we provide a theoretical
+context for the formation of super-Earth clouds by determining which
+condensates are likely to form under the assumption of chemical equilibrium. We
+study super-Earth atmospheres of diverse bulk composition, which are assumed to
+form by outgassing from a solid core of chondritic material, following Schaefer
+& Fegley (2010). The super-Earth atmospheres that we study arise from planetary
+cores made up of individual types of chondritic meteorites. They range from
+highly reducing to oxidizing and have carbon to oxygen (C:O) ratios that are
+both subsolar and super-solar, thereby spanning a range of atmospheric
+composition that is appropriate for low-mass exoplanets. Given the atomic
+makeup of these atmospheres, we minimize the global Gibbs free energy of
+formation for over 550 gases and condensates to obtain the molecular
+composition of the atmospheres over a temperature range of 350-3,000 K. Clouds
+should form along the temperature-pressure boundaries where the condensed
+species appear in our calculation. We find that the composition of condensate
+clouds depends strongly on both the H:O and C:O ratios. For the super-Earth
+archetype GJ 1214b, KCl and ZnS are the primary cloud-forming condensates at
+solar composition, in agreement with previous work (Morley et al. 2013;
+Miller-Ricci Kempton et al. 2012). However, for oxidizing atmospheres, K2SO4
+and ZnO condensates are favored instead, and for carbon-rich atmospheres with
+super-solar C:O ratios, graphite clouds appear. For even hotter planets, clouds
+form from a wide variety of rock-forming and metallic species.",1602.02759v2
+2016-02-09,Quantum states entanglement in hemoglobin molecule active center,"An ab initio study of the electronic and spin configuration for the iron ion
+in the active center of the human hemoglobin molecule is presented. It is well
+known that the iron ion, being surrounded by the porphyrin ring and the
+ligands, plays the key role in the realization of the basic oxygen-transport
+functions of the molecule. This work is focused on the investigation the
+features of the 3$d$-shell electronic states of the iron ion located inside the
+active center of the hemoglobin molecule. Also in this paper we study in detail
+the changes in these states occurring during the oxidation process. We use a
+combination of the Density Functional Theory (DFT) method and the Dynamical
+Mean Field Theory (DMFT) approach. This method allows to consider dynamic
+correlation effects that are important in the description of systems containing
+transition metal ions. It was found that the state of the valence electrons of
+the iron ion of the active center of hemoglobin molecule is the entangled
+quantum state. This state is a mixture of several electronic states with
+comparable statistical probability. Furthermore, it was found that the process
+of the bond formation between the iron-porphyrin complex and the oxygen
+molecule is more complex than a simple high-spin to low-spin state of the Fe
+ion transition. The transition metal ion oxidation is accompanied by
+substantial redistribution of the states probabilities and the increasing of
+the entanglement degree. This process also leads to the reduction of the total
+spin moment from $s\approx$2.1 for the FeP(Im) to $s\approx$1.7 for the
+FeP(Im)(O$_2$).",1602.02963v2
+2016-02-09,Room-temperature quantum transport signatures in graphene/LaAlO3/SrTiO3 heterostructures,"The pseudospin quantum degree of freedom is one of the most remarkable
+properties of graphene that distinguishes it from ordinary two-dimensional
+metals and semiconductors. Pseudospin quantum interference leads to weak
+antilocalization (WAL) and is influenced strongly by point defects and thermal
+perturbations that break chirality and destroy phase coherence. Preserving and
+manipulating quantum transport properties up to room temperature is key to
+realizing practical pseudospin-based graphene devices. Here we report
+fabrication and transport characterization of graphene field-effect devices on
+a complex-oxide heterostructure, LaAlO3/SrTiO3. Signatures of WAL, a
+consequence of pseudospin quantum interference, persist up to room temperature.
+The LaAlO3/SrTiO3 substrate plays a critical role in suppressing short-range
+impurity scattering and electron-phonon coupling. The observation of quantum
+transport signatures at room temperature is unique to this system and presents
+new opportunities for the development of pseudospin-based devices and novel
+multifunctional devices that couple to the complex-oxide interface.",1602.03128v3
+2016-03-08,Ligand-Surface Interactions and Surface Oxidation of Colloidal PbSe Quantum Dots Revealed by Thin-film Positron Annihilation Methods,"Positron Two Dimensional Angular Correlation of Annihilation Radiation
+(2D-ACAR) measurements reveal modifications of the electronic structure and
+composition at the surfaces of PbSe quantum dots (QDs), deposited as thin
+films, produced by various ligands containing either oxygen or nitrogen atoms.
+In particular, the 2D-ACAR measurements on thin films of colloidal PbSe QDs
+capped with oleic acid ligands yield an increased intensity in the electron
+momentum density (EMD) at high momenta compared to PbSe quantum dots capped
+with oleylamine. Moreover, the EMD of PbSe QDs is strongly affected by the
+small ethylediamine ligands, since these molecules lead to small distances
+between QDs and favor neck formation between near neighbor QDs, inducing
+electronic coupling between neighboring QDs. The high sensitivity to the
+presence of oxygen atoms at the surface can be also exploited to monitor the
+surface oxidation of PbSe QDs upon exposure to air. Our study clearly
+demonstrates that positron annihilation spectroscopy applied to thin films can
+probe surface transformations of colloidal semiconductor QDs embedded in
+functional layers.",1603.02547v1
+2016-04-12,Systematic spatial and stoichiometric screening towards understanding the surface of ultrasmall oxygenated silicon nanocrystal,"In most of the realistic ab initio and model calculations which have appeared
+on the emission of light from Si nanocrystals, the role of surface oxygen has
+been usually ignored, underestimated or completely ruled out. We investigate
+theoretically, by density functional theory (DFT/B3LYP) possible modes of
+oxygen bonding in hydrogen terminated silicon quantum dots using as a
+representative case of the Si29 nanocrystal. We have considered Bridge-bonded
+oxygen (BBO), Doubly-bonded oxygen (DBO), hydroxyl (OH) and Mix of these
+oxidizing agents. Due to stoichiometry, all comparisons performed are unbiased
+with respect to composition whereas spatial distribution of oxygen species
+pointed out drastic change in electronic and cohesive characteristics of
+nanocrytals. From an overall perspective of this study, it is shown that bridge
+bonded oxygenated nanocrystals accompanied by Mix have higher binding energies
+and large electronic gap compared to nanocrystals with doubly bonded oxygen
+atoms. In addition, it is observed that the presence of OH along with BBO, DBO
+and mixed configurations further lowers electronic gaps and binding energies
+and trends. It is also demonstrated that oxidizing constituent besides their
+spatial distribution significantly alters binding energy and highest occupied
+molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) gap
+(HOMO-LUMO gap up to 1.48 eV) within same composition.",1604.03528v1
+2016-04-15,Single crystal growth from separated educts and its application to lithium transition-metal oxides,"Thorough mixing of the starting materials is the first step of a crystal
+growth procedure. This holds true for almost any standard technique, whereas
+the intentional separation of educts is considered to be restricted to a very
+limited number of cases. A noticeable exception is the crystal growth in gels
+that allows for a better control of the nucleation by limiting the diffusion.
+The successful application of this principle to open systems, however, has
+remained elusive. Here we show that single crystals of {\alpha}-Li2IrO3 can be
+grown from separated educts in an open crucible in air. Elemental lithium and
+iridium are oxidized and transported over a distance of typically one
+centimeter in an isothermal process. Single crystals grow from an exposed
+condensation point placed in between the educts. The method has also been
+applied to the growth of Li2RuO3, Li2PtO3 and {\beta}-Li2IrO3 and a successful
+use for various other materials is anticipated.",1604.04551v4
+2016-04-27,Polyelectrolyte assisted charge titration spectrometry: applications to latex and oxide nanoparticles,"The electrostatic charge density of particles is of paramount importance for
+the control of the dispersion stability. Conventional methods use
+potentiometric, conductometric or turbidity titration but require large amount
+of samples. Here we report a simple and cost-effective method called
+polyelectrolyte assisted charge titration spectrometry or PACTS. The technique
+takes advantage of the propensity of oppositely charged polymers and particles
+to assemble upon mixing, leading to aggregation or phase separation. The mixed
+dispersions exhibit a maximum in light scattering as a function of the
+volumetric ratio X, and the peak position XMax is linked to the particle charge
+density according to {\sigma} ~ D0 XMax where D0 is the particle diameter. The
+PACTS is successfully applied to organic latex, aluminum and silicon oxide
+particles of positive or negative charge using poly(diallyldimethylammonium
+chloride) and poly(sodium 4-styrenesulfonate). The protocol is also optimized
+with respect to important parameters such as pH and concentration, and to the
+polyelectrolyte molecular weight. The advantages of the PACTS technique are
+that it requires minute amounts of sample and that it is suitable to a broad
+variety of charged nano-objects.",1604.08033v1
+2016-06-20,Anisotropic electron-phonon coupling in the spinel oxide superconductor,"Among hundreds of spinel oxides, LiTi2O4 (LTO) is the only one that exhibits
+superconductivity (Tc ~13 K). Although the general electron-phonon coupling is
+still the main mechanism for electron pairing in LTO, unconventional behaviors
+such as the anomalous magnetoresistance, anisotropic orbital/spin
+susceptibilities, etc. reveal that both the spin and the orbital interactions
+should also be considered for understanding the superconductivity. Here, we
+investigate tunneling spectra of [111]-, [110]- and [001]-oriented high quality
+LTO thin films. Several bosonic modes in tunneling spectra are observed in the
+[111]- and [110]-oriented films but not in [001]-oriented ones, and these modes
+still exist at T = 2Tc and beyond the upper critical field, which are confirmed
+as stemming from electron-phonon interaction by DFT calculations. These modes
+only appear in special surface orientations, indicating that the
+electron-phonon coupling in LTO system is highly anisotropic and may be
+enhanced by orbital-related state. The anisotropic electron-phonon coupling
+should be taken seriously in understanding the nature of LTO superconductivity.",1606.06109v3
+2016-06-24,Π Band Dispersion along Conjugated Organic Nanowires Synthesized on a Metal Oxide Semiconductor,"Surface confined dehalogenation reactions are versatile bottom-up approaches
+for the synthesis of carbon-based nanostructures with predefined chemical
+properties. However, for devices generally requiring low conductivity
+substrates, potential applications are so far severely hampered by the
+necessity of a metallic surface to catalyze the reactions. In this work we
+report the synthesis of ordered arrays of poly(p-phenylene) chains on the
+surface of semiconducting TiO2(110) via a dehalogenative homocoupling of
+4,4""-dibromoterphenyl precursors. The supramolecular phase is clearly
+distinguished from the polymeric one using low energy electron diffraction and
+scanning tunneling microscopy as the substrate temperature used for deposition
+is varied. X ray photoelectron spectroscopy of C 1s and Br 3d core levels
+traces the temperature of the onset of dehalogenation to around 475 K.
+Moreover, angle-resolved photoemission spectroscopy and tight-binding
+calculations identify a highly dispersive band characteristic of a substantial
+overlap between the precursor's {\pi} states along the polymer, considered as
+the fingerprint of a successful polymerization. Thus, these results establish
+the first spectroscopic evidence that atomically precise carbon based
+nanostructures can readily be synthesized on top of a transition-metal oxide
+surface, opening the prospect for the bottom-up production of novel
+molecule-semiconductor devices.",1606.07638v1
+2016-06-30,Metal-Insulator Transition and the Role of Electron Correlation in FeO2,"Iron oxide is a key compound to understand the state of the deep Earth. It
+has been believed that previously known oxides such as FeO and Fe2O3 will be
+dominant at the mantle conditions. However, recent observation of FeO2 shed
+another light to the composition of the deep lower mantle (DLM) and thus
+understanding of the physical properties of FeO2 will be critical to model DLM.
+Here, we report the electronic structure and structural properties of FeO2 by
+using density functional theory (DFT) and dynamic mean field theory (DMFT). The
+crystal structure of FeO2 is composed of Fe2+ and O2 2- dimers, where the Fe
+ions are surround by the octahedral O atoms. We found that the bond length of
+O2 dimer, which is very sensitive to the change of the Coulomb interaction U of
+Fe 3d orbital, plays an important role in determining the electronic
+structures. The band structures of DFT+DMFT show that the metal-insulator
+transition is driven by the change of U and pressure. We suggest that the
+correlation effect should be considered to correctly describe the physical
+properties of FeO2 compound.",1606.09582v2
+2016-07-07,An internal disulfide locks a misfolded aggregation-prone intermediate in cataract-linked mutants of human γD-crystallin,"Considerable mechanistic insight has been gained into amyloid aggregation;
+however, a large class of non-amyloid protein aggregates are considered
+'amorphous,' and in most cases little is known about their mechanisms.
+Amorphous aggregation of {\gamma}-crystallins in the eye lens causes a
+widespread disease of aging, cataract. We combined simulations and experiments
+to study the mechanism of aggregation of two {\gamma}D-crystallin mutants, W42R
+and W42Q - the former a congenital cataract mutation, and the latter a mimic of
+age-related oxidative damage. We found that formation of an internal disulfide
+was necessary and sufficient for aggregation under physiological conditions.
+Two-chain all-atom simulations predicted that one non-native disulfide in
+particular, between Cys32 and Cys41, was likely to stabilize an unfolding
+intermediate prone to intermolecular interactions. Mass spectrometry and
+mutagenesis experiments confirmed the presence of this bond in the aggregates
+and its necessity for oxidative aggregation under physiological conditions in
+vitro. Mining the simulation data linked formation of this disulfide to
+extrusion of the N-terminal \b{eta}-hairpin and rearrangement of the native
+\b{eta}-sheet topology. Specific binding between the extruded hairpin and a
+distal \b{eta}-sheet, in an intermolecular chain reaction similar to domain
+swapping, is the most probable mechanism of aggregate propagation.",1607.02110v1
+2016-07-11,Dynamic Modulation of the Transport Properties of the LaAlO3/SrTiO3 Interface Using Uniaxial Strain,"Among the interfacial transport modulations to the LaAlO3/SrTiO3 (LAO/STO)
+heterostructure, mechanical strain has been proven to be an effective approach
+by growing the LAO/STO films on different substrates with varying lattice
+mismatches to STO. However, this lattice-mismatch-induced strain effect is
+static and biaxial, hindering the study of the strain effect in a dynamic way.
+In this work we realize dynamic and uniaxial strain to the LAO/STO oxide
+heterostructure at low temperature, through mechanical coupling from a
+magnetostrictive template. This anisotropic strain results in symmetry breaking
+at the interface and induces further splitting of the electronic band structure
+and therefore produces different conductivities along the x and y in-plane
+directions. In particular, we observe that along the strained direction the
+interface conductivity decreases by up to 70% under a tensile strain, while it
+increases by 6.8% under a compressive strain at 2 K. Also, it is revealed that
+the modulation on the interfacial transport property can be anisotropic, i.e.,
+the resistance changes differently when an excitation current is parallel or
+perpendicular to the strain direction. This approach of strain engineering
+provides another degree of freedom for control of transport properties of oxide
+heterostructures and opens an additional way to investigate strain effects in
+materials science.",1607.02808v1
+2016-07-24,Evidence for percolation diffusion of cations and material recovery in disordered pyrochlore from accelerated molecular dynamics simulations,"We used classical and accelerated molecular dynamics simulations to
+characterize vacancy-mediated diffusion of cations in Gd$_2$Ti$_2$O$_7$
+pyrochlore as a function of the disorder on the microsecond timescale. We find
+that cation vacancy diffusion is slow in materials with low levels of disorder.
+However, higher levels of disorder allow for fast cation diffusion, which is
+then also accompanied by fast antisite annihilation and ordering of the
+cations. The cation diffusivity is therefore not constant, but decreases as the
+material reorders. The results suggest that fast cation diffusion is triggered
+by the existence of a percolation network of antisites. This is in marked
+contrast with oxygen diffusion, which showed a smooth increase of the ionic
+diffusivity with increasing disorder in the same compound. The increase of the
+cation diffusivity with disorder is also contrary to observations from other
+complex oxides and disordered media models, suggesting a fundamentally
+different relation between disorder and mass transport. These results highlight
+the dynamic interplay between fast cation diffusion and the recovery of
+disorder and have important implications for understanding radiation damage
+evolution, sintering and aging, as well as diffusion in disorder oxides more
+generally.",1607.07101v1
+2016-09-02,"Ab-initio study of structural, vibrational and optical properties of solid oxidizers","We report the structural, elastic and vibrational properties of five
+ionic-molecular solid oxidizers MNO$_3$ (M = Li, Na, K) and MClO$_3$ (M = Na,
+K). By treating long range electron-correlation effects, dispersion corrected
+method leads to more accurate predictions of structural properties and phase
+stability of KNO$_3$ polymorphs. The obtained elastic moduli show soft nature
+of these materials and are consistent with Ultrasonic Pulse Echo measurements.
+We made a complete assignment of vibrational modes which are in good accord
+with available experimental results. From calculated IR and Raman spectra, it
+is found that the vibrational frequencies show a red-shift from Li -> Na -> K
+(Na -> K) and N -> Cl for nitrates (chlorates) due to increase in mass of metal
+and non-metal atoms, respectively. The calculated electronic structure using
+recently developed Tran-Blaha modified Becke-Johnson potential show that the
+materials are wide band gap insulators with predominant ionic bonding between
+M$^+$ (metal) and NO$_3^-$ /ClO$_3^-$ ions and covalent bonding (N-O and Cl-O)
+within nitrate and chlorate anionic group. From the calculated optical spectra,
+we observe that electric-dipole transitions are due to nitrate/chlorate group
+below 20 eV and cationic transitions occur above 20 eV. The calculated
+reflectivity spectra are consistent with the available experimental spectra.",1609.00473v1
+2016-09-20,Compaction and flow rule of oxide nanopowders,"Transparent Al2O3 ceramics have attracted considerable interest for use in a
+wide range of optical, electronic and structural applications. The fabrication
+of these ceramics using powder metallurgy processes requires the development of
+theoretical approaches to the compaction of nanopowders. In this work, we
+investigate the compaction processes of two model granular systems imitating
+Al2O3 nanosized powders. System I is a loosely aggregated powder, and system II
+is a powder strongly inclined to agglomeration (for instance, calcined powder).
+The processes of isostatical (uniform), biaxial, and uniaxial compaction as
+well as uniaxial compaction with simultaneous shear deformation are studied.
+The energy parameters of compaction such as the energy change of elastic
+interparticle interactions and dispersion interactions, dissipative energy
+losses related to the processes of interparticle friction, and the total work
+of compaction are calculated for all the processes. The nonapplicability of the
+associated flow rule to the description of deformation processes of oxide
+nanopowders is shown and an alternative plastic flow rule is suggested. A
+complete system of determining the relationship of the flow including
+analytical approximations of yield surfaces is obtained.",1609.06099v1
+2016-09-24,First principles modeling of defects in the Al_2O_3/In_0.53Ga_0.47As system,"Density functional theory paired with a first order many-body perturbation
+theory correction is applied to determine formation energies and charge
+transition energies for point defects in bulk In_0.53Ga_0.47As and for models
+of the In_0.53Ga_0.47As/Al_2O_3 interface. The results are consistent with
+previous computational studies that As_Ga antisites are candidates for defects
+observed in capacitance voltage measurements on metal-oxide-semiconductor
+capacitors, as the As_Ga antisite introduces energy states near the valence
+band maximum and near the middle of the energy band gap. However, substantial
+broadening in the distribution of the Ga_As charge transition levels due to the
+variation in the local chemical environment resulting from alloying on the
+cation (In/Ga) sublattice is found, whereas this effect is absent for As_Ga
+antisites. Also, charge transition energy levels are found to vary based on
+proximity to the semiconductor/oxide interface. The combined effects of alloy-
+and proximity-shift on the Ga_As antisite charge transition energies are
+consistent with the distribution of interface defect levels between the valence
+band edge and midgap as extracted from electrical characterization data. Hence,
+kinetic growth conditions leading to a high density of either Ga_As or As_Ga
+antisites near the In_0.53Ga_0.47As/Al_2O_3 interface are both consistent with
+defect energy levels at or below midgap.",1609.07624v1
+2016-10-06,Diminish Electrostatic in Piezoresponse Force Microscopy through longer ultra-stiff tips,"Piezoresponse Force Microscopy is a powerful but delicate nanoscale technique
+that measures the mechanical response resulting from the application of a
+highly localized electric field. Though mechanical response is normally due to
+piezoelectricity, other physical phenomena, especially electrostatic
+interaction, can contribute to the signal read. We address this problematic
+through the use of longer ultra-stiff probes providing state of the art
+sensitivity, with the lowest electrostatic interaction and avoiding working in
+high frequency regime. In order to find this solution we develop a theoretical
+description addressing the effects of electrostatic contributions in the total
+cantilever vibration and its quantification for different setups. The theory is
+subsequently tested in a Periodically Poled Lithium Niobate (PPLN) crystal, a
+sample with well-defined 0deg and 180deg domains, using different commercial
+available conductive tips. We employ the theoretical description to compare the
+electrostatic contribution effects into the total phase recorded. Through
+experimental data our description is corroborated for each of the tested
+commercially available probes. We propose that a larger probe length can be a
+solution to avoid electrostatic forces, so the cantilever-sample electrostatic
+interaction is reduced. For hard oxide samples we propose an ultra-stiff
+cantilever which avoids the use of high frequency voltage but still diminishing
+electrostatic forces. Our proposed commercially available solution have great
+implications into avoiding artifacts while studying soft biological samples,
+multiferroic oxides, and thin film ferroelectric materials and it opens a new
+window into tip engineering.",1610.01809v1
+2016-10-11,Valley splitting of single-electron Si MOS quantum dots,"Silicon-based metal-oxide-semiconductor quantum dots are prominent candidates
+for high-fidelity, manufacturable qubits. Due to silicon's band structure,
+additional low-energy states persist in these devices, presenting both
+challenges and opportunities. Although the physics governing these valley
+states has been the subject of intense study, quantitative agreement between
+experiment and theory remains elusive. Here, we present data from a new
+experiment probing the valley states of quantum dot devices and develop a
+theory that is in quantitative agreement with both the new experiment and a
+recently reported one. Through sampling millions of realistic cases of
+interface roughness, our method provides evidence that, despite radically
+different processing, the valley physics between the two samples is essentially
+the same. This work provides the first evidence that valley splitting can be
+deterministically predicted and controlled in metal oxide semiconductor quantum
+dots, a critical requirement for such systems to realize a reliable qubit
+platform.",1610.03388v1
+2016-10-11,Measurement Error in Atomic-Scale STEM-EDS Mapping of a Model Oxide Interface,"With the development of affordable aberration-correctors, analytical scanning
+transmission electron microscopy (STEM) studies of complex interfaces can now
+be conducted at high spatial resolution at laboratories worldwide.
+Energy-dispersive X-ray spectroscopy (STEM-EDS) in particular has grown in
+popularity, since it enables elemental mapping over a wide range of ionization
+energies. However, the interpretation of atomically-resolved data is greatly
+complicated by beam-sample interactions that are often overlooked by novice
+users. Here we describe the practical factors---namely, sample thickness and
+the choice of ionization edge---that affect the quantification of a model
+perovskite oxide interface. Our measurements of the same sample in regions of
+different thickness indicate that interface profiles can vary by as much as 2-5
+unit cells, depending on the spectral feature. This finding is supported by
+multislice simulations, which reveal that on-axis maps of even perfectly abrupt
+interfaces exhibit significant delocalization. Quantification of thicker
+samples is further complicated by channeling to heavier sites across the
+interface, as well as an increased signal background. We show that extreme care
+must be taken to prepare samples to minimize channeling effects and argue that
+it may not be possible to extract atomically-resolved information from many
+chemical maps.",1610.03432v2
+2016-10-18,Blue Phosphorene Oxide: Strain-tunable Quantum Phase Transitions and Novel 2D Emergent Fermions,"Tunable quantum phase transitions and novel emergent fermions in solid state
+materials are fascinating subjects of research. Here, we propose a new stable
+two-dimensional (2D) material, the blue phosphorene oxide (BPO), which exhibits
+both. Based on first-principles calculations, we show that its equilibrium
+state is a narrow-bandgap semiconductor with three bands at low energy.
+Remarkably, a moderate strain can drive a semiconductor-to-semimetal quantum
+phase transition in BPO. At the critical transition point, the three bands
+cross at a single point at Fermi level, around which the quasiparticles are a
+novel type of 2D pseudospin-1 fermions. Going beyond the transition, the system
+becomes a symmetry-protected semimetal, for which the conduction and valence
+bands touch quadratically at a single Fermi point that is protected by
+symmetry, and the low-energy quasiparticles become another novel type of 2D
+double Weyl fermions. We construct effective models characterizing the phase
+transition and these novel emergent fermions, and we point out several exotic
+effects, including super Klein tunneling, supercollimation, and universal
+optical absorbance. Our result reveals BPO as an intriguing platform for the
+exploration of fundamental properties of quantum phase transitions and novel
+emergent fermions, and also suggests its great potential in nanoscale device
+applications.",1610.05399v2
+2016-10-24,The Role of H2O and O2 Molecules and Phosphorus Vacancies in the Structure Instability of Phosphorene,"The poor structural stability of phosphorene in air was commonly ascribed to
+humidity and oxygen molecules. Recent exfoliation of phosphorene in
+deoxygenated water promotes the need to re-examine the role of H2O and O2
+molecules. Considering the presence of high population of vacancies in
+phosphorene, we investigate the interaction of H2O and O2 molecules with
+vacancy-contained phosphorene using first-principles calculations. In contrast
+to the common notion that physisorbed molecules tend to have a stronger
+adsorption at vacancy sites, we show that H2O has nearly the same adsorption
+energy at the vacancy site as that at the perfect one. Charge transfer analysis
+shows that O2 is a strong electron scavenger, which transfers the lone-pair
+electrons of the phosphorus atoms to the 2{\pi}* antibonding orbital of O2. As
+a result, the barrier for the O-O bond splitting to form O-P bonds is reduced
+from 0.81 eV at the perfect site to 0.59 eV at the defect site, leading to an
+about 5000 faster oxidizing rate at the defect site than at the perfect site at
+room temperature. Hence, our work reveals that the vacancy in phosphorene shows
+a stronger oxygen affinity than the perfect phosphorene lattice site.
+Structural degradation of phosphorene due to oxidization may occur rapidly at
+edges and grain boundaries where vacancies tend to agglomerate.",1610.07512v1
+2017-02-17,Effect of Sr-doping of LaMnO3 spacer on modulation-doped two-dimensional electron gases at oxide interfaces,"Modulation-doped oxide two-dimensional electron gas (2DEG) formed at the
+LaMnO3 (LMO) buffered disorderd-LaAlO3/SrTiO3 (d-LAO/LMO/STO) heterointerface,
+provides new opportunities for electronics as well as quantum physics. Herein,
+we studied the dependence of Sr-doping of La1-xSrxMnO3 (LSMO, x=0, 1/8, 1/3,
+1/2, and 1) thus the filling of the Mn eg subbands as well as the LSMO polarity
+on the transport properties of d-LAO/LSMO/STO. Upon increasing the LSMO film
+thickness from 1 unit cell (uc) to 2 uc, a sharp metal to insulator transition
+of interface conduction was observed, independent of x. The resultant electron
+mobility is often higher than 1900 cm2V-1s-1 at 2 K, which increases upon
+decreasing x. The sheet carrier density, on the other hand, is in the range of
+6.9E1012~1.8E1013 cm-2 (0.01~0.03 e/uc) and is largely independent on x for all
+the metallic d-LAO/LSMO (1 uc)/STO interfaces. These results are consistent
+with the charge transfer induced modulation doping scheme and clarify that the
+polarity of the buffer layer plays a trivial role on the modulation doping. The
+negligible tunability of the carrier density could result from the reduction of
+LSMO during the deposition of disordered LAO or that the energy levels of Mn 3d
+electrons at the interface of LSMO/STO are hardly varied even when changing the
+LSMO composition from LMO to SrMnO3.",1702.05256v1
+2017-02-18,Soft-proton exchange on Magnesium-oxide-doped substrates a route toward efficient and power-resistant nonlinear converters,"Despite its attractive features, Congruent-melted Lithium Niobate (CLN)
+suffers from Photo-Refractive Damage (PRD). This light-induced refractive-index
+change hampers the use of CLN when high-power densities are in play, a typical
+regime in integrated optics. The resistance to PRD can be largely improved by
+doping the lithium-niobate substrates with magnesium oxide. However, the
+fabrication of waveguides on MgO-doped substrates is not as effective as for
+CLN: either the resistance to PRD is strongly reduced by the waveguide
+fabrication process (as it happens in Ti-indiffused waveguides) or the
+nonlinear conversion efficiency is lowered (as it occurs in annealed-proton
+exchange). Here we fabricate, for the first time, waveguides starting from
+MgO-doped substrates using the Soft-Proton Exchange (SPE) technique and we show
+that this third way represents a promising alternative. We demonstrate that SPE
+allows to produce refractive-index profiles almost identical to those produced
+on CLN without reducing the nonlinearity in the substrate. We also prove that
+the SPE does not affect substantially the resistance to PRD. Since the
+fabrication recipe is identical between CLN and MgO-doped substrates, we
+believe that SPE might outperform standard techniques to fabricate robust and
+efficient waveguides for high-intensity-beam confinement.",1702.05590v1
+2017-03-01,Atomically precise lateral modulation of a two-dimensional electron liquid in anatase TiO2 thin films,"Engineering the electronic band structure of two-dimensional electron liquids
+(2DELs) confined at the surface or interface of transition metal oxides is key
+to unlocking their full potential. Here we describe a new approach to tailoring
+the electronic structure of an oxide surface 2DEL demonstrating the lateral
+modulation of electronic states with atomic scale precision on an unprecedented
+length scale comparable to the Fermi wavelength. To this end, we use pulsed
+laser deposition to grow anatase TiO2 films terminated by a (1 x 4) in-plane
+surface reconstruction. Employing photo-stimulated chemical surface doping we
+induce 2DELs with tunable carrier densities that are confined within a few TiO2
+layers below the surface. Subsequent in-situ angle resolved photoemission
+experiments demonstrate that the (1 x 4) surface reconstruction provides a
+periodic lateral perturbation of the electron liquid. This causes strong
+backfolding of the electronic bands, opening of unidirectional gaps and a
+saddle point singularity in the density of states near the chemical potential.",1703.00157v1
+2017-08-10,Oxygen Partial Pressure during Pulsed Laser Deposition: Deterministic Role on Thermodynamic Stability of Atomic Termination Sequence at SrRuO3/BaTiO3 Interface,"With recent trends on miniaturizing oxide-based devices, the need for
+atomic-scale control of surface/interface structures by pulsed laser deposition
+(PLD) has increased. In particular, realizing uniform atomic termination at the
+surface/interface is highly desirable. However, a lack of understanding on the
+surface formation mechanism in PLD has limited a deliberate control of
+surface/interface atomic stacking sequences. Here, taking the prototypical
+SrRuO3/BaTiO3/SrRuO3 (SRO/BTO/SRO) heterostructure as a model system, we
+investigated the formation of different interfacial termination sequences
+(BaO-RuO2 or TiO2-SrO) with oxygen partial pressure (PO2) during PLD. We found
+that a uniform SrO-TiO2 termination sequence at the SRO/BTO interface can be
+achieved by lowering the PO2 to 5 mTorr, regardless of the total background gas
+pressure (Ptotal), growth mode, or growth rate. Our results indicate that the
+thermodynamic stability of the BTO surface at the low-energy kinetics stage of
+PLD can play an important role in surface/interface termination formation. This
+work paves the way for realizing termination engineering in functional oxide
+heterostructures.",1708.03089v1
+2017-08-10,A Design Based on Stair-case Band Alignment of Electron Transport Layer for Improving Performance and Stability in Planar Perovskite Solar Cells,"Among the n-type metal oxide materials used in the planar perovskite solar
+cells, zinc oxide (ZnO) is a promising candidate to replace titanium dioxide
+(TiO2) due to its relatively high electron mobility, high transparency, and
+versatile nanostructures. Here, we present the application of low temperature
+solution processed ZnO/Al-doped ZnO (AZO) bilayer thin film as electron
+transport layers (ETLs) in the inverted perovskite solar cells, which provide a
+stair-case band profile. Experimental results revealed that the power
+conversion efficiency (PCE) of perovskite solar cells were significantly
+increased from 12.25 to 16.07% by employing the AZO thin film as the buffer
+layer. Meanwhile, the short-circuit current density (Jsc), open-circuit voltage
+(Voc), and fill factor (FF) were improved to 20.58 mA/cm2, 1.09V, and 71.6%,
+respectively. The enhancement in performance is attributed to the modified
+interface in ETL with stair-case band alignment of ZnO/AZO/CH3NH3PbI3, which
+allows more efficient extraction of photogenerated electrons in the CH3NH3PbI3
+active layer. Thus, it is demonstrated that the ZnO/AZO bilayer ETLs would
+benefit the electron extraction and contribute in enhancing the performance of
+perovskite solar cells.",1708.03153v1
+2017-08-24,Influence of inversion on Mg mobility and electrochemistry in spinels,"Magnesium oxide and sulfide spinels have recently attracted interest as
+cathode and electrolyte materials for energy-dense Mg batteries, but their
+observed electrochemical performance depends strongly on synthesis conditions.
+Using first principles calculations and percolation theory, we explore the
+extent to which spinel inversion influences Mg$^{2+}$ ionic mobility in
+MgMn$_2$O$_4$ as a prototypical cathode, and MgIn$_2$S$_4$ as a potential solid
+electrolyte. We find that spinel inversion and the resulting changes of the
+local cation ordering give rise to both increased and decreased Mg$^{2+}$
+migration barriers, along specific migration pathways, in the oxide as well as
+the sulfide.
+  To quantify the impact of spinel inversion on macroscopic Mg$^{2+}$
+transport, we determine the percolation thresholds in both MgMn$_2$O$_4$ and
+MgIn$_2$S$_4$. Furthermore, we analyze the impact of inversion on the
+electrochemical properties of the MgMn$_2$O$_4$ cathode via changes in the
+phase behavior, average Mg insertion voltages and extractable capacities, at
+varying degrees of inversion. Our results confirm that inversion is a major
+performance limiting factor of Mg spinels and that synthesis techniques or
+compositions that stabilize the well-ordered spinel structure are crucial for
+the success of Mg spinels in multivalent batteries.",1708.07458v1
+2017-08-28,Limits in point to point resolution of MOS (Metal-Oxide-Semiconductor) based pixels detector arrays,"In high energy physics point to point resolution is a key prerequisite for
+particle detector pixel arrays. Current and future experiments require the
+development of inner-detectors able to resolve the tracks of particles down to
+the micron range. Present-day technologies, although not fully implemented in
+actual detectors can reach a 5 micometer limit, based on statistical
+measurements, with a pixel-pitch in the 10 micrometer range. Attempts to design
+small pixels based on SOI (Silicon On Insulator) technology will be briefly
+recalled here. This paper is devoted to the evaluation of the building blocks
+with regard to their use in pixel arrays for the accurate tracking of the
+charged particles. We will make here a simulations based quantitative
+evaluation of the physical limits in the pixel size. A design based on CMOS
+(Complementary Metal-Oxide-Semiconductor) compatible technologies that allows a
+reduction of the pixel size down to the sub-micronmeter range is introduced.
+Its physical principle relies on a buried carrier-localizing collecting gate.
+The fabrication process needed by this pixel design can be based on existing
+process steps used in silicon microelectronics. The pixel characteristics will
+be discussed as well as the design of pixel arrays. The existing bottlenecks
+and how to overcome them will be discussed in the light of recent ion
+implantation and material characterization.",1708.08330v4
+2018-02-08,Limitation of atmospheric composition by combustion-explosion in exoplanetary atmospheres,"This work presents theoretical studies which combine aspects of combustion
+and explosion theory with exoplanetary atmospheric science. Super Earths could
+possess a large amount of molecular hydrogen depending on disk, planetary and
+stellar properties. Super Earths orbiting pre-main sequence-M-dwarf stars have
+been suggested to possess large amounts of O2 produced abiotically via water
+photolysis followed by hydrogen escape . If these two constituents were present
+simultaneously, such large amounts of H2 and O2 can react via photochemistry to
+form up to about 10 Earth oceans. In cases where photochemical removal is slow
+so that O2 can indeed build up abiotically, the atmosphere could reach the
+combustion explosion limit. Then, H2 and O2 react extremely quickly to form
+water together with modest amounts of hydrogen peroxide. These processes set
+constraints for H2 O2 atmospheric compositions in Super Earth atmospheres. Our
+initial study of the gas-phase oxidation pathways for modest conditions with
+Earth insolation and about a tenth of a percent of H2 suggests that H2 is
+oxidized by O2 into H2O mostly via HOx and mixed HOx NOx catalyzed cycles.
+Regarding other atmospheric species-pairs we find that CO,O2 mixtures could
+attain explosive combustive levels on mini gas planets for mid range for the C
+to O ratio in the equilibrium chemistry regime for p more than about 1bar.
+Regarding CH4,O2 mixtures, a small number of modeled rocky planets assuming
+Earth like atmospheres orbiting cooler stars could have compositions at or near
+the explosive combustive level although more work is required to investigate
+this issue.",1802.02923v1
+2018-02-13,Effect of support on the vanadyl oxygen abstraction in supported vanadia,"Supported vanadia catalysts are modeled within the cluster DFT approach to
+get an insight into the mechanism in which the support affects the activity of
+vanadia in the oxidation processes. The energy of the V=O group dissociation
+chosen as a descriptor of the oxidation activity is estimated using two aligned
+divanadate V2O3(OH)4 particles at various distances. Separation between
+particles allows to imitate (i) the various supporting materials (e.g. TiO2,
+SiO2, etc.), and (ii) the coverage of vanadia on a particular support. A
+substantial compensation of the energy loss upon the vanadyl oxygen abstraction
+via bonding to the vanadyl oxygen of neighboring vanadate particle has been
+predicted. On account of such compensation the overall energy of the V=O
+dissociation reaches its minimal value of 36 kcal/mol (dropping from maximum of
+142 kcal/mol) at small separation of 3 {\AA} between dimers when the nearest
+vanadyl oxygen occupies a bridge V-O-V position. For dimers separated by about
+4 {\AA}, the dissociation energy achieves its maximal value for isolated dimers
+of about 143 kcal/mol. Thus, these findings allows one to conclude that the
+oxygen mobility is a result of a compensation effect in a chain-like bonding
+between neighboring vanadyl groups on the surface of support.",1802.04496v2
+2018-04-03,"Thermal theory of aluminum particle ignition in continuum, free-molecular, and transition heat transfer regimes","Most studies on nano- and micro- sized aluminum particle ignition have been
+focused on the processes occuring inside particles. In the current paper,
+thermal ignition of an aluminum particle in the air is simulated with different
+heat transfer models: continuum, free-molecular and Fuchs model. A single
+parabolic oxidation law is assumed in the particle size range from nano- to
+millimeter diameters. A particle is considered ignited when it reaches the
+oxide melting point. The criterion defining the limits of validity for each
+model is the ratio of continuum and free-molecular heat transfer rates. The
+dependence of ignition temperature $T_i$ on particle size is in a qualitative
+agreement with the experimental trends: $T_i$ can have values in the range
+700--1500 K for nanoparticles due to the dominating contribution of a
+free-molecular heat transfer, and sharp growth of $T_i$ with the particle size
+in the range of 1-100 $\mu$m diameter is due to the transitional character of
+heat transfer. For small values of accommodation coefficient, ignition may
+occur in the critical ignition mode with the thermal runaway. The results
+suggest the importance of heat transfer and, in particular, energy
+accommodation in ignition of nano- and micro- sized particles.",1804.01192v2
+2018-04-08,Quantifying Confidence in DFT Predicted Surface Pourbaix Diagrams and Associated Reaction Pathways for Chlorine Evolution,"Density functional theory calculations can be used to identify dominant
+reaction mechanisms. However, the dominant reaction mechanism is sensitive to
+choice of the exchange correlation functional. Here, we demonstrate using the
+example case of chlorine evolution reaction on rutile oxides, which can occur
+through at least three reaction mechanisms each mediated by different surface
+intermediates and active sites. We utilize Bayesian error estimation
+capabilities within the BEEF-vdW exchange correlation (XC) functional to
+quantify the uncertainty associated with predictions of the operative reaction
+mechanism by systematically propagating the uncertainty originating from
+DFT-computed adsorption free energies. We construct surface Pourbaix diagrams
+based on the calculated adsorption free energies for rutile oxides of Ru, Ir,
+Ti, Pt, V, Sn and Rh. We utilize confidence-value (c-value) to determine the
+degree of confidence in the predicted surface phase diagrams. Using the scaling
+relations between the adsorption energies of intermediates we construct a
+generalized Pourbaix diagram showing the stable surface composition as a
+function of potential and the oxygen binding energy on the cus site. This is
+used to consistently determine activity volcano relationships. We incorporate
+the uncertainty in linear scaling relations to quantify the confidence in
+generalized Pourbaix diagram and the associated activity. This allows us to
+compute the expectation limiting potential as a function of $\Delta E_{O^c}$,
+which provides a more appropriate activity measure incorporating DFT
+uncertainty. We show that the confidence in the classification problem of
+identifying the active reaction mechanism is much better than the prediction
+problem of determining catalytic activity.",1804.02766v1
+2018-04-09,Inversion Charge-boost and Transient Steep-slope induced by Free charge-polarization Mismatch in a Ferroelectric-metal-oxide-semiconductor Capacitor,"In this letter, the transient behavior of a ferroelectric (FE)
+metal-oxide-semiconductor (MOS) capacitor is theoretically investigated with a
+series resistor. It is shown that compared to a conventional high-k dielectric
+MOS capacitor, a significant inversion charge-boost can be achieved by a FE MOS
+capacitor due to a steep transient subthreshold swing (SS) driven by the free
+charge-polarization mismatch. It is also shown that the observation of steep
+transient SS significantly depends on the viscosity coefficient under Landau's
+mean field theory, in general representing the average FE time response
+associated with domain nucleation and propagation. Therefore, this letter not
+only establishes a theoretical framework that describes the physical origin
+behind the inversion charge-boost in a FE MOS capacitor, but also shows that
+the key feature of depolarization effect on a FE MOS capacitor should be the
+inversion-charge boost, rather than the steep SS (e.g., sub-60mV/dec at room
+temperature), which cannot be experimentally observed as the measurement time
+is much longer than the FE response. Finally, we outlines the required material
+targets for the FE response in field-effect transistors to be applicable for
+next-generation high-speed and low-power digital switches.",1804.03125v1
+2018-04-18,High order synaptic learning in neuro-mimicking resistive memories,"Memristors have demonstrated immense potential as building blocks in future
+adaptive neuromorphic architectures. Recently, there has been focus on
+emulating specific synaptic functions of the mammalian nervous system by either
+tailoring the functional oxides or engineering the external programming
+hardware. However, high device-to-device variability in memristors induced by
+the electroforming process and complicated programming hardware are among the
+key challenges that hinder achieving biomimetic neuromorphic networks. Here, an
+electroforming-free and complementary metal oxide semiconductor
+(CMOS)-compatible memristor based on oxygen-deficient SrTiO$_{3-x}$ (STO$_x$)
+is reported to imitate synaptic learning rules. Through spectroscopic and
+cross-sectional transmission electron microscopic analyses, electroforming-free
+characteristics are attributed to the bandgap reduction of STO$_x$ by the
+formation of oxygen vacancies. The potential of such memristors to behave as
+artificial synapses is demonstrated by successfully implementing high order
+time- and rate-dependent synaptic learning rules. Also, a simple hybrid
+CMOS-memristor approach is presented to implement a variety of synaptic
+learning rules. Results are benchmarked against biological measurements form
+hippocampal and visual cortices with good agreement. This demonstration is a
+step towards the realization of large scale adaptive neuromorphic computation
+and networks.",1804.06688v1
+2018-04-19,Confinement- and strain-induced enhancement of thermoelectric properties in LaNiO$_3$/LaAlO$_3(001)$ superlattices,"By combining ab initio simulations including an on-site Coulomb repulsion
+term and Boltzmann theory, we explore the thermoelectric properties of
+(LaNiO$_3$)$_n$/(LaAlO$_3$)$_n$(001) superlattices ($n=1,3$) and identify a
+strong dependence on confinement, spacer thickness, and epitaxial strain. While
+the system with $n=3$ shows modest values of the Seebeck coefficient and power
+factor, the simultaneous reduction of the LaNiO$_3$ region and the LaAlO$_3$
+spacer thickness to single layers results in a strong enhancement, in
+particular of the in-plane values. This effect can be further tuned by using
+epitaxial strain as control parameter: Under tensile strain corresponding to
+the lateral lattice constant of SrTiO$_3$ we predict in- and cross-plane
+Seebeck coefficients of $\pm 600$ $\mu$V/K and an in-plane power factor of $11$
+$\mu$W/K$^2$cm for an estimated relaxation time of $\tau = 4$ fs around room
+temperature. These values are comparable to some of the best performing oxide
+systems such as La-doped SrTiO$_3$ or layered cobaltates and are associated
+with the opening of a small gap ($0.29$ eV) induced by the concomitant effect
+of octahedral tilting and Ni-site disproportionation. This establishes oxide
+superlattices at the verge of a metal-to-insulator transition driven by
+confinement and strain as promising candidates for thermoelectric materials.",1804.07070v2
+2018-04-24,Gelation of Plasmonic Metal Oxide Nanocrystals by Polymer-Induced Depletion-Attractions,"Gelation of colloidal nanocrystals (NCs) emerged as a strategy to preserve
+inherent nanoscale properties in multiscale architectures. Yet available
+gelation methods still struggle to reliably control nanoscale optical phenomena
+such as photoluminescence and localized surface plasmon resonance (LSPR) across
+NC systems due to processing variability. Here, we report on an alternative
+gelation method based on physical inter-NC interactions: short-range
+depletion-attractions balanced by long-range electrostatic repulsions. The
+latter are established by removing the native organic ligands that passivate
+tin-doped indium oxide (ITO) NCs while the former are introduced by mixing with
+small polyethylene glycol (PEG) chains. As we incorporate increasing
+concentrations of PEG, we observe a reentrant phase behavior featuring two
+favorable gelation windows; the first arises from bridging effects while the
+second is attributed to depletion-attractions according to phase behavior
+predicted by our unified theoretical model. The NCs remain discrete within the
+gel network, based on X-ray scattering and high-resolution transmission
+electron microscopy. The infrared optical response of the gel is reflective of
+both the NC building blocks and the network architecture, being characteristic
+of ITO NC LSPR with coupling interactions between neighboring NCs.",1804.09106v1
+2018-04-25,"Testing the influence of the temperature, RH and filler type and content on the Universal Power Law for new reduced graphene oxide TPU composites","In this paper, 6 different reduced graphene oxide (rGO) were prepared by a
+modified Hummers method and reduced by thermochemical methods. rGO materials
+were intentionally prepared to obtain different BET and thickness and oxygen
+content maintaining constant the lateral size to compare its performance on
+thermoplastic polyurethane (TPU) matrix. Microstructure and the effect of the
+incorporation of rGO on the hardness and electrical properties of TPU were
+investigated. It has been studied the temperature and humidity dependence of
+the electrical conductivity and the sensitivity and the response time to
+humidity changes have been determined. Influence of the filler content,
+temperature and humidity on the Jonschers universal power law (UPL) for ac
+conductivity vs frequency and its fitting parameters A and n were determined.
+It has been observed an anomalous behaviour (according to UPL) and a linear
+correlation between log A and n independently of the filler content, humidity
+and temperature, however there is an influence of the rGO used for the
+preparation of the composite. To study the transport mechanisms the
+experimental results were adjusted to the equation and the maximum adjustment
+for like other carbon nanocomposites however there is not an unequivocal
+behaviour.",1804.09361v1
+2018-04-13,Influence of post-deposition annealing on the chemical states of crystalline tantalum pentoxide films,"We investigate the effect of post-deposition annealing (for temperatures from
+848 K to 1273 K) on the chemical properties of crystalline Ta$_2$O$_5$ films
+grown on Si(100) substrates by radio frequency magnetron sputtering. The atomic
+arrangement, as determined by X-ray diffraction, is predominately hexagonal
+($\delta$-Ta$_2$O$_5$) for the films exposed to heat treatments at 948 K and
+1048 K; orthorhombic ($\beta$-Ta$_2$O$_5$) for samples annealed at 1148 K and
+1273 K; and amorphous for samples annealed at temperatures below 948 K. X-ray
+photoelectron spectroscopy for Ta $4f$ and O $1s$ core-levels were performed to
+evaluate the chemical properties of all films as a function of annealing
+temperature. Upon analysis, it is observed the Ta $4f$ spectrum characteristic
+of Ta in Ta$^{5+}$ and the formation of Ta-oxide phases with oxidation states
+Ta$^{1+}$, Ta$^{2+}$, Ta$^{3+}$, and Ta$^{4+}$. The study reveals that the
+increase in annealing temperature increases the percentage of the state
+Ta$^{5+}$ and the reduction of the others indicating that higher temperatures
+are more desirable to produce Ta$_2$O$_5$, however, there seems to be an
+optimal annealing temperature that maximizes the O\% to Ta\% ratio. We found
+that at 1273 K the ratio slightly reduces suggesting oxygen depletion.",1804.09538v2
+2018-11-01,The origin of negative charging in amorphous Al$_2$O$_3$ films: The role of native defects,"Amorphous aluminum oxide Al$_2$O$_3$ (a-Al$_2$O$_3$) layers grown by various
+deposition techniques contain a significant density of negative charges. In
+spite of several experimental and theoretical studies, the origin of these
+charges still remains unclear. We report the results of extensive Density
+Functional Theory (DFT) calculations of native defects - O and Al vacancies and
+interstitials, as well as H interstitial centers - in different charge states
+in both crystalline $\alpha$-Al$_2$O$_3$ and in a-Al$_2$O$_3$. The results
+demonstrate that both the charging process and the energy distribution of traps
+responsible for negative charging of a-Al$_2$O$_3$ films [M. B. Zahid et al.,
+IEEE Trans. Electron Devices 57, 2907 (2010)] can be understood assuming that
+the negatively charged O$_{\textrm{i}}$ and V$_{\textrm{Al}}$ defects are
+nearly compensated by the positively charged H$_{\textrm{i}}$, V$_{\textrm{O}}$
+and Al$_{\textrm{i}}$ defects in as prepared samples. Following electron
+injection, the states of Al$_{\textrm{i}}$, V$_{\textrm{O}}$ or
+H$_{\textrm{i}}$ in the band gap become occupied by electrons and sample
+becomes negatively charged. The optical excitation energies from these states
+into the oxide conduction band agree with the results of exhaustive
+photo-depopulation spectroscopy (EPDS) measurements [M. B. Zahid et al., IEEE
+Trans. Electron Devices 57, 2907 (2010)]. This new understanding of the origin
+of negative charging of a-Al$_2$O$_3$ films is important for further
+development of nanoelectronic devices and solar cells.",1811.00610v2
+2018-11-14,Multifrequency Nanoscale Impedance Microscopy (m-NIM): A novel approach towards detection of selective and subtle modifications on the surface of polycrystalline boron-doped diamond electrodes,"In this paper, we describe the modification of Nanoscale Impedance Microscopy
+(NIM), namely, a combination of contact-mode atomic force microscopy with local
+impedance measurements. The postulated approach is based on the application of
+multifrequency voltage perturbation instead of standard frequency-by-frequency
+analysis, which among others offers more time-efficient and accurate
+determination of the resultant impedance spectra with high spatial resolution.
+Based on the impedance spectra analysis with an appropriate electric equivalent
+circuit, it was possible to map surface resistance and contact capacitance.
+Polycrystalline heavy boron-doped diamond (BDD) electrodes were the research
+object. Recent studies have shown that the exposure of such electrodes to
+oxidizing environment may result in the modification of termination type, and
+thus it is a key factor in describing the electric and electrochemical
+properties of BDD. We have successfully applied multifrequency NIM, which
+allowed us to prove that the modification of termination type is selective and
+occurs with different propensity on the grains having specific crystallographic
+orientation. Furthermore, our approach enabled the detection of even subtle
+submicroscopic surface heterogeneities, created as a result of various
+oxidation treatments and to distinguish them from the surface heterogeneity
+related to the local distribution of boron at the grain boundaries.",1811.05709v1
+2018-11-30,Dynamically switching the surface electronic and electrostatic properties of indium tin oxide electrodes with photochromic monolayers,"The chemical modification of electrodes with organic materials is a common
+approach to tune the electronic and electrostatic landscape between interlayers
+in optoelectronic devices, thus facilitating charge injection at the
+electrode/semiconductor interfaces and improving their performance. The use of
+photochromic molecules for the surface modification allows dynamic control of
+the electronic and electrostatic properties of the electrode and thereby
+enables additional functionalities in such devices. Here, we show that the
+electronic properties of a transparent indium tin oxide (ITO) electrode are
+reversibly and dynamically modified by depositing organic photochromic switches
+(diarylethenes) in the form of self-assembled monolayers (SAMs). By combining a
+range of surface characterization and density functional theory calculations,
+we present a detailed picture of the SAM binding onto ITO, the packing density
+of molecules, their orientation, as well as the work function modification of
+the ITO surface due to the SAM deposition. Upon illumination with ultraviolet
+and green light, we observe a reversible shift of the frontier occupied levels
+by 0.7 eV, and concomitantly a reversible work function change of ca. 60 meV.
+Our results prove the viability of dynamic switching of the electronic
+properties of the electrode with external light stimuli, which could be used to
+fabricate ITO-based photo-switchable optoelectronic devices.",1811.12741v1
+2019-05-02,Demonstration of Sputtering Atomic Layer Augmented Deposition (SALAD): Aluminum Oxide-Copper Dielectric-Metal Nanocomposite,"Designing a thin film structure often begins with choosing a film deposition
+method that employs a specific primary process by which chemical species are
+formed and transported. In other words, a film deposition system in which two
+complementary deposition methods are hybridized should lead to new ways of
+designing thin film structures with structural complexity tailored at a level
+that has never been envisioned.This premise inspired us to uniquely combine
+atomic layer deposition (ALD) and magnetron sputtering (SPU) within a single
+deposition chamber; the combined film deposition system is referred to as
+sputtering atomic layer augmented deposition (SALAD). SALAD allows us to take
+full advantages of both ALDs precise and accurate precursor delivery and SPUs
+versatility in choices of chemical elements. A SALAD system was designed based
+on knowledge obtained by computational fluid dynamics with the goal of
+conceiving a film deposition system that satisfied deposition conditions
+distinctive for both ALD and SPU, and a prototype SALAD system was assembled by
+employing off-the-shelf vacuum components.A s a demonstration, the SALAD system
+was utilized to deposit a unique nanocomposite made of a stack of aluminum
+oxide thin films by ALD and copper thin films by SPU, AlOx-Cu dielectric-metal
+(ACDM) nanocomposite thin films, on Si and glass substrates. Spectroscopic
+reflectivity collected on ACDM nanocomposite thin films shows unique dispersion
+features to which conventional effective medium theories used for describing
+optical properties of composites made of a dielectric host that contains
+metallic inclusions do not seem to simply apply.",1905.00584v2
+2019-05-02,All Inkjet-Printed Graphene-Silver Composite Inks for Highly Conductive Wearable E-Textiles Applications,"Inkjet-printed wearable electronic textiles (e-textiles) are considered to be
+very promising due to excellent processing and environmental benefits offered
+by digital fabrication technique. Inkjet-printing of conductive metallic inks
+such as silver (Ag) nanoparticles (NPs) are well-established and that of
+graphene-based inks is of great interest due to multi-functional properties of
+graphene-based materials. However, poor ink stability at higher graphene
+concentration and the cost associated with the higher Ag loading in metal inks
+have limited their wider use. Moreover, graphene-based e-textiles reported so
+far are mainly based on graphene derivatives such as graphene oxide (GO) or
+reduced graphene oxide (rGO), which suffers from poor electrical conductivity.
+Here we report inkjet printing of highly conductive and cost-effective
+graphene/Ag composite inks for wearable e-textiles applications. The composite
+inks were formulated, characterised and inkjet-printed onto PEL paper first and
+then sintered at 150 C for 1 hr. The sheet resistance of the printed patterns
+is found to be in the range of ~0.08 - 4.74 ohm/sq depending on the number of
+print layers and the graphene/Ag ratio in the formulation. The optimised
+composite ink was then successfully printed onto surface pre-treated (by inkjet
+printing) cotton fabrics in order to produce all-inkjet-printed highly
+conductive and cost-effective electronic textiles.",1905.00839v1
+2019-05-03,Anisotropic Proton and Oxygen Ion Conductivity in Epitaxial Ba2In2O5 Thin Films,"Solid oxide oxygen ion and proton conductors are a highly important class of
+materials for renewable energy conversion devices like solid oxide fuel cells.
+Ba2In2O5 (BIO) exhibits both oxygen ion and proton conduction, in dry and humid
+environment, respectively. In dry environment, the brownmillerite crystal
+structure of BIO exhibits an ordered oxygen ion sublattice, which has been
+speculated to result in anisotropic oxygen ion conduction. The hydrated
+structure of BIO, however, resembles a perovskite and the protons in it were
+predicted to be ordered in layers. To complement the significant theoretical
+and experimental efforts recently reported on the potentially anisotropic
+conductive properties in BIO, we measure here the proton and oxygen ion
+conductivity along different crystallographic directions. Using epitaxial thin
+films with different crystallographic orientations the charge transport for
+both charge carriers is shown to be anisotropic. The anisotropy of the oxygen
+ion conduction can indeed be explained through the layered structure of the
+oxygen sublattice in brownmillerite BIO. The anisotropic proton conduction
+however, further supports the suggested ordering of the protonic defects in the
+material. The differences in proton conduction along different crystallographic
+directions attributed to proton ordering in BIO are of a similar extent as
+those observed along different crystallographic directions in materials where
+proton ordering is not present but where protons find preferential conduction
+pathways through chain-like or layered structures.",1905.01113v1
+2019-05-05,Improving mobility of silicon metal-oxide-semiconductor devices for quantum dots by high vacuum activation annealing,"To improve mobility of fabricated silicon metal-oxide-semiconductor (MOS)
+quantum devices, forming gas annealing is a common method used to mitigate the
+effects of disorder at the Si/SiO2 interface. However, the importance of
+activation annealing is usually ignored. Here, we show that a high vacuum
+environment for implantation activation is beneficial for improving mobility
+compared to nitrogen atmosphere. Low-temperature transport measurements of Hall
+bars show that peak mobility can be improved by a factor of two, reaching 1.5
+m^2/(Vs) using high vacuum annealing during implantation activation. Moreover,
+the charge stability diagram of a single quantum dot is mapped, with no visible
+disturbance caused by disorder, suggesting possibility of fabricating
+high-quality quantum dots on commercial wafers. Our results may provide
+valuable insights into device optimization in silicon-based quantum computing.",1905.01581v2
+2019-05-11,ExoMol Molecular linelists -- XXXIII. The spectrum of Titanium Oxide,"Accurate line lists are crucial for correctly modelling a variety of
+astrophysical phenomena, including stellar photospheres and the atmospheres of
+extra-solar planets. This paper presents a new line database Toto for the main
+isotopologues of titanium oxide (TiO): $^{46}$Ti$^{16}$O, $^{47}$Ti$^{16}$O,
+$^{48}$Ti$^{16}$O, $^{49}$Ti$^{16}$O and $^{50}$Ti$^{16}$O. The TiO line list
+contains transitions with wave-numbers up to 30,000 cm$^{-1}$ ie long-wards of
+0.33 $\mu$m. The Toto line list includes all dipole-allowed transitions between
+13 low-lying electronic states (X $^3\Delta$, a $^1\Delta$, d $^1\Sigma^+$, E
+$^3\Pi$, A $^3\Phi$ B $^3\Pi$, C $^3\Delta$, b $^1\Pi$, c $^1\Phi$, f
+$^1\Delta$, e $^1\Sigma^+$). Ab initio potential energy curves (PECs) are
+computed at the icMRCI level and combined with spin-orbit and other coupling
+curves. These PECs and couplings are iteratively refined to match known
+empirical energy levels. Accurate line intensities are generated using ab
+initio dipole moment curves. The Toto line lists are appropriate for
+temperatures below 5000 K and contain 30 million transitions for TiO; it is
+made available in electronic form via the CDS data centre and via
+www.exomol.com. Tests of the line lists show greatly improved agreement with
+observed spectra for objects such as M-dwarfs GJ876 and GL581.",1905.04587v2
+2019-05-13,Velocity Saturation in La-doped BaSnO3 Thin Films,"BaSnO_{3}, a high mobility perovskite oxide, is an attractive material for
+oxide-based electronic devices. However, in addition to low-field mobility,
+high-field transport properties such as the saturation velocity of carriers
+play a major role in determining device performance. We report on the
+experimental measurement of electron saturation velocity in La-doped BaSnO_{3}
+thin films for a range of doping densities. Predicted saturation velocities
+based on a simple LO-phonon emission model using an effective LO phonon energy
+of 120 meV show good agreement with measurements of velocity saturation in
+La-doped BaSnO_{3} films.. Density-dependent saturation velocity in the range
+of 1.6x10^{7} cm/s reducing to 2x10^{6} cm/s is predicted for {\delta}-doped
+BaSnO3 channels with carrier densities ranging from 10^{13} cm^{-2} to
+2x10^{14} cm^{-2} respectively. These results are expected to aid the informed
+design of BaSnO3 as the active material for high-charge density electronic
+transistors.",1905.05112v2
+2019-05-16,"Phase composition and transformations in magnetron-sputtered (Al,V)2O3 coatings","Coatings of (Al1-xVx)2O3, with x ranging from 0 to 1, were deposited by
+pulsed DC reactive sputter deposition on Si(100) at a temperature of 550
+{\deg}C. XRD showed three different crystal structures depending on V-metal
+fraction in the coating: {\alpha}-V2O3 rhombohedral structure for 100 at.% V, a
+defect spinel structure for the intermediate region, 63 - 42 at.% V. At lower
+V-content, 18 and 7 at.%, a gamma-alumina-like solid solution was observed,
+shifted to larger d-spacing compared to pure {\gamma}-Al2O3. The microstructure
+changes from large columnar faceted grains for {\alpha}-V2O3 to smaller
+equiaxed grains when lowering the vanadium content toward pure {\gamma}-Al2O3.
+Annealing in air resulted in formation of V2O5 crystals on the surface of the
+coating after annealing to 500 {\deg}C for 42 at.% V and 700 {\deg}C for 18
+at.% V metal fraction respectively. The highest thermal stability was shown for
+pure {\gamma}-Al2O3-coating, which transformed to {\alpha}-Al2O3 after
+annealing to 1100{\deg} C. Highest hardness was observed for the Al-rich
+oxides, ~24 GPa. The latter decreased with increasing V-content, larger than 7
+at.% V metal fraction. The measured hardness after annealing in air decreased
+in conjunction with the onset of further oxidation of the coatings.",1905.06714v2
+2019-05-22,The polymorphous nature of cubic halide perovskites,"It has been long known that numerous halide and oxide perovskites can have
+non-ideal octahedra, showing tilting, rotation, and metal atom displacements.
+It has also been known that compounds that have at low temperatures a single
+structural motif (""monomorphous structures"") could become disordered at higher
+temperatures, resulting in non-ideal octahedra as an entropy effect. What is
+shown here is that in many cubic halide perovskites and some oxides compounds a
+distribution of different low-symmetry octahedra (""polymorphous networks"")
+emerge already from the minimization of the systems internal energy, i.e., they
+represent the intrinsic, preferred low temperature pattern of chemical bonding.
+Thermal disorder effects build up at elevated temperatures on top of such low
+temperature polymorphous networks. Compared with the monomorphous counterparts,
+the polymorphous networks have lower predicted total energies (enhanced
+stability), larger band gaps and dielectric constants now dominated by the
+ionic part, and agrees much more closely with the observed pair distribution
+functions. The nominal cubic perovskites (Pm-3m) structure deduced from X-Ray
+diffraction is actually a macroscopically averaged, high symmetry
+configuration, which should not be used to model electronic properties, given
+that the latter reflect a low symmetry local configuration.",1905.09141v3
+2019-05-24,"Quasiparticle band structure and optical properties of rutile GeO$_2$, an ultra-wide-band-gap semiconductor","Rutile GeO$_2$ is a visible and near-ultraviolet-transparent oxide that has
+not been explored for semiconducting applications in electronic and
+optoelectronic devices. We investigate the electronic and optical properties of
+rutile GeO$_2$ with first-principles calculations based on density functional
+theory and many-body perturbation theory. Our band-structure calculations
+indicate a dipole-forbidden direct band gap at $\Gamma$ with an energy of 4.44
+eV and effective masses equal to $m^*_{e\perp}$ =0.43$m_0$ , $m^*_{e||}$
+=0.23$m_0$ , $m^*_{h\perp}$ =1.28$m_0$ , and $m^*_{h||}$=1.74$m_0$ . In
+contrast to the self-trapped hole polarons by lattice distortions in other
+wide-band-gap oxides that reduce the hole mobility, holes in rutile GeO$_2$ are
+delocalized due to their small effective mass. The first allowed optical
+transitions at $\Gamma$ occur at 5.04 eV ($\vec{E} \perp \vec{c}$) and 6.65 eV
+($\vec{E} ||\vec{c} $). We also evaluate the optical absorption coefficient and
+refractive index along both crystallographic directions. Our estimates for the
+exciton binding energies using the Bohr model are close to the reported
+experimental value. The ultra-wide-band-gap and light carrier effective masses
+of rutile GeO$_2$, coupled with its optical transparency in the visible and
+near UV are promising for applications in UV-transparent conductors and
+solar-blind photodetectors.",1905.10301v2
+2019-05-30,Sr-induced dipole scatter in BST: Insights from MD simulations using a transferable bond valence-based interatomic potential,"In order to design next-generation ferroelectrics, a microscopic
+understanding of their macroscopic properties is critical. One means to
+achieving an atomistic description of ferroelectric and dielectric phenomena is
+classical molecular dynamics simulations. Previously, we have shown that
+interatomic potentials based on the bond valence molecular dynamics (BVMD)
+method can be used to study structural phase transitions, ferroelectric domain
+nucleation, and domain wall migration in several perovskite oxides and
+fixed-composition binary and ternary alloys. Most modern devices, however, use
+variable-composition perovskite oxide alloys such as Ba$_x$Sr$_{1-x}$TiO$_3$
+(BST). In this paper, we extend our bond valence approach to BST solid
+solutions and, in so doing, show that the potential parameters for each element
+are transferable between materials with different $x$. Using this potential, we
+perform BVMD simulations investigating the temperature and composition
+dependence of the lattice constants, Ti displacements, and ferroelectric
+polarization of BST and find that our predictions match experiments and
+first-principles theory. Additionally, based on a detailed analysis of local
+dipole distributions, we demonstrate that substitution of Sr for Ba scrambles
+dipoles, reduces global polarization, and enhances the order-disorder character
+of the ferroelectric-paraelectric phase transition.",1905.13201v1
+2020-06-30,"COTS MOS Dosimetry on the MeMOSat Board, Results After 2.5 Years in Orbit","We present the results after 2.5 years in or-bit of Total Ionizing Dose (TID)
+measurements done using Metal Oxide Semiconductor (MOS) dosimeters on the
+MeMOSat board. The MeMOSat board was launched on July 19th 2014 at the BugSat-1
+""Tita"" microsatellite developed by Satellogic to stay at LEO. We used as
+dosimeters p-channel Commercial Off The Shelf (COTS) MOS transistors with gate
+oxides of 250~nm. Before launch, a subset of transistors with similar drain
+current to voltage (I-V)curves where selected from a group of 100 devices. The
+temperature dependence of the (I-V) curves was studied to find the minimum
+temperature coefficient biasing point. Then, a calibration subgroup of sensors
+was irradiated using a $^{60}$Co gamma source to study their response to TID,
+showing responsivities of $\sim$75~mV/krad when the sensors are irradiated
+without gate bias. Also, the post irradiation response of the sensors was
+monitored, in order to include a correction for low dose rate irradiations,
+yielding 30~mV/krad. A biasing and reading circuit was developed in order to
+allow the reading of up to 4 sensors.The threshold voltage was monitored during
+different periods of the mission. After 2.5 years in orbit,the threshold
+voltage of the sensor mounted on the MeMOSat Board had a V$_\mathrm{T}$ shift
+of approximately 35~mV corresponds to a dose of 1.2~krads.",2007.00143v1
+2020-07-02,Enhanced graphitic domains of unreduced graphene oxide and the interplay of hydration behaviour and catalytic activity,"Previous studies indicate that the properties of graphene oxide (GO) can be
+significantly improved by enhancing its graphitic domain size through thermal
+diffusion and clustering of functional groups. Remarkably, this transition
+takes place below the decomposition temperature of the functional groups and
+thus allows fine-tuning of graphitic domains without compromising with the
+functionality of GO. By studying the transformation of GO under mild thermal
+treatment, we directly observe this size enhancement of graphitic domains from
+originally 40 nm2 to 200 nm2 through an extensive transmission electron
+microscopy (TEM) study. Additionally, we confirm the integrity of the
+functional groups during this process by comprehensive chemical analysis. A
+closer look into the process confirms the theoretically predicted relevance for
+the room temperature stability of GO. We further investigate the influence of
+enlarged graphitic domains on the hydration behaviour of GO and catalytic
+performance of single-atom catalysts supported by GO.",2007.00860v5
+2020-07-07,A switchable two-dimensional electron gas based on ferroelectric Ca:SrTiO$_3$,"Two-dimensional electron gases (2DEGs) can form at the surface of oxides and
+semiconductors or in carefully designed quantum wells and interfaces. Depending
+on the shape of the confining potential, 2DEGs may experience a finite electric
+field, which gives rise to relativistic effects such as the Rashba spin-orbit
+coupling. Although the amplitude of this electric field can be modulated by an
+external gate voltage, which in turn tunes the 2DEG carrier density, sheet
+resistance and other related properties, this modulation is volatile. Here, we
+report the design of a ''ferroelectric'' 2DEG whose transport properties can be
+electrostatically switched in a non-volatile way. We generate a 2DEG by
+depositing a thin Al layer onto a SrTiO$_3$ single crystal in which 1 percent
+of Sr is substituted by Ca to make it ferroelectric. Signatures of the
+ferroelectric phase transition at 25 K are visible in the Raman response and in
+the temperature dependences of the carrier density and sheet resistance that
+shows a hysteretic dependence on electric field as a consequence of
+ferroelectricity. We suggest that this behavior may be extended to other oxide
+2DEGs, leading to novel types of ferromagnet-free spintronic architectures.",2007.03344v1
+2020-07-08,Structure motif centric learning framework for inorganic crystalline systems,"Incorporation of physical principles in a network-based machine learning (ML)
+architecture is a fundamental step toward the continued development of
+artificial intelligence for materials science and condensed matter physics. In
+this work, as inspired by the Pauling rule, we propose that structure motifs
+(polyhedral formed by cations and surrounding anions) in inorganic crystals can
+serve as a central input to a machine learning framework for crystalline
+inorganic materials. Taking metal oxides as examples, we demonstrated that, an
+unsupervised learning algorithm Motif2Vec is able to convert the presence of
+structure motifs and their connections in a large set of crystalline compounds
+into unique vector representations. The connections among complex materials can
+be largely determined by the presence of different structure motifs and their
+clustering information are identified by our Motif2Vec algorithm. To
+demonstrate the novel use of structure motif information, we show that a
+motif-centric learning framework can be effectively created by combining motif
+information with the recently developed atom-based graph neural networks to
+form an atom-motif dual graph network (AMDNet). Taking advantage of node and
+edge information on both atomic and motif level, the AMDNet is more accurate
+than an atom graph network in predicting electronic structure related material
+properties of metal oxides such as band gaps. The work illustrates the route
+toward fundamental design of graph neural network learning architecture for
+complex material properties by incorporating beyond-atom physical principles.",2007.04145v1
+2020-07-12,Fabrication of Germanium-on-insulator in a Ge wafer with a crystalline Ge top layer and buried GeO2 layer by Oxygen ion implantation,"The paper reports fabrication of Germanium-on-Insulator (GeOI) wafer by
+Oxygen ion implantation of an undoped single crystalline Ge wafer of
+orientation (100). Oxygen ions of energy 200 keV were implanted. The implanted
+wafer was subjected to Rapid Thermal Annealing to 650 C. The resulting wafer
+has a top crystalline Ge layer of 220 nm thickness and Buried Oxide layer (BOX)
+layer of good quality crystalline Germanium oxide with thickness around 0.62
+micron. The crystalline BOX layer has hexagonal crystal structure with lattice
+constants close to the standard values. Raman Spectroscopy, cross-sectional
+HRTEM with SAED and EDS established that the top Ge layer was recrystallized
+during annealing with faceted crystallites. The top layer has a small tensile
+strain of around +0.4\% and has estimated dislocation density of 2.7 x
+10^{7}cm^{-2}. The thickness, crystallinity and electrical characteristics of
+the top layer and the quality of the BOX layer of GeO_{2} are such that it can
+be utilized for device fabrication.",2007.05897v1
+2020-07-12,Artificial two-dimensional polar metal by charge transfer to a ferroelectric insulator,"Integrating multiple properties in a single system is crucial for the
+continuous developments in electronic devices. However, some physical
+properties are mutually exclusive in nature. Here, we report the coexistence of
+two seemingly mutually exclusive properties-polarity and two-dimensional
+conductivity-in ferroelectric Ba$_{0.2}$Sr$_{0.8}$TiO$_3$ thin films at the
+LaAlO$_3$/Ba$_{0.2}$Sr$_{0.8}$TiO$_3$ interface at room temperature. The
+polarity of a ~3.2 nm Ba$_{0.2}$Sr$_{0.8}$TiO$_3$ thin film is preserved with a
+two-dimensional mobile carrier density of ~0.05 electron per unit cell. We show
+that the electronic reconstruction resulting from the competition between the
+built-in electric field of LaAlO$_3$ and the polarization of
+Ba$_{0.2}$Sr$_{0.8}$TiO$_3$ is responsible for this unusual two-dimensional
+conducting polar phase. The general concept of exploiting mutually exclusive
+properties at oxide interfaces via electronic reconstruction may be applicable
+to other strongly-correlated oxide interfaces, thus opening windows to new
+functional nanoscale materials for applications in novel nanoelectronics.",2007.05903v1
+2020-07-14,Mass Production of Two-Dimensional Materials by Intermediate-Assisted Grinding Exfoliation,"The scalable and high-efficiency production of two-dimensional (2D) materials
+is a prerequisite to their commercial use. Currently, only graphene and
+graphene oxide can be produced on a ton scale, and the inability to produce
+other 2D materials on such a large scale hinders their technological
+applications. Here we report a grinding exfoliation method that uses
+micro-particles as force intermediates to resolve applied compressive forces
+into a multitude of small shear forces, inducing the highly-efficient
+exfoliation of layer materials. The method, referred to as
+intermediate-assisted grinding exfoliation (iMAGE), can be used for the
+large-scale production of many 2D materials. As an example, we have exfoliated
+bulk h-BN into 2D h-BN with large flake sizes, high quality and structural
+integrity, with a high exfoliation yield of 67%, a high production rate of 0.3
+g h-1 and a low energy consumption of 3.01x10^6 J g-1. The production rate and
+energy consumption are one to two orders of magnitude better than previous
+results. Besides h-BN, this iMAGE technology has been used to exfoliate various
+layer materials such as graphite, black phosphorus, transition metal
+dichalcogenides, and metal oxides, proving its universality. Molybdenite
+concentrate, a natural low-cost and abundant mineral, was used as a demo for
+the large-scale exfoliation production of 2D MoS2 flakes. Our work indicates
+the huge potential of the iMAGE method to produce large amounts of various 2D
+materials, which paves the way for their commercial application.",2007.06921v1
+2020-07-24,Integration of multi-layer black phosphorus into photoconductive antennas for THz emission,"We report the fabrication, characterization, and modeling of photoconductive
+antennas using 40 nm thin-film flakes of black phosphorus (BP) as the
+photoconductor and hexagonal boron nitride (hBN) as a capping layer to prevent
+oxidation of BP. Dipole antennas were fabricated on oxidized high-resistivity
+Si substrates, and BP and hBN flakes were picked up and transferred onto the
+antenna inside a nitrogen glovebox. The transfer matrix technique was used to
+optimize the thickness of BP and hBN for maximum absorption. BP flakes were
+aligned with the armchair axis along the anode-cathode gap of the antenna, with
+crystal orientation measured using reflection anisotropy. Photocurrent imaging
+under illumination with 100 fs pulses at 780 and 1560 nm showed a
+bias-dependent maximum photocurrent localized to the antenna gap with a peak
+photoconductivity of 1 (2) S/cm in the linear regime of bias for excitation at
+780 (1560) nm. Photocurrent saturation in bias (pump fluence) occurred at
+approximately 1 V (0.25 mJ/cm$^2$). Device performance was modeled numerically
+by solving Maxwell's equations and the drift-diffusion equation to obtain the
+photocurrent density in response to pulsed laser excitation, which was largely
+in qualitative agreement with the experimental observations. THz output
+computed from surface current density suggests that BP THz PCA performance is
+at least comparable to more traditional devices based on low-temperature-grown
+GaAs. These devices represent a step toward high-performance THz
+photoconductive antennas using BP.",2007.12775v1
+2020-07-25,Industrial manufacturing and characterization of multiscale CFRP laminates made from prepregs containing graphene-related materials,"The introduction of graphene-related materials (GRMs) in carbon
+fibre-reinforced polymers (CFRP) has been proved to enhance their mechanical
+and electrical properties. However, methodologies to produce the 3-phase
+materials (multiscale composites) at an industrial scale and in an efficient
+manner are still lacking. In this paper, multiscale CFRP composites containing
+different GRMs have been manufactured following standard procedures currently
+used in the aerospace industry with the aim to evaluate its potential
+application. Graphite nanoplateletelets (GNPs), in situ exfoliated graphene
+oxide (GO) and reduced graphene oxide (rGO) have been dispersed into an epoxy
+resin to subsequently impregnate aeronautical grade carbon fibre tape. The
+resulting prepregs have been used for manufacturing laminates by hand lay-up
+and autoclave curing at 180 {\deg}C. Abroad characterization campaign has been
+carried out to understand the behaviour of the different multiscale laminates
+manufactured. The degree of cure, glass transition temperature and degradation
+temperature have been evaluated by thermal evolution techniques. Similarly,
+their mechanical properties (tensile, flexural, in-plane shear, interlaminar
+shear and mode I interlaminar fracture toughness) have been analysed together
+with their electrical conductivity. The manufacturing process resulted
+appropriated for producing three-phase laminates and their quality was as good
+as in conventional CFRPs. The addition ofGOand rGO resulted in an enhancement
+of the in-plane shear properties and delamination resistance while the addition
+ofGNPimproved the electrical conductivity.",2007.12902v1
+2020-07-28,Aluminum oxide nucleation in the early stages of atomic layer deposition on epitaxial graphene,"In this work, the nucleation and growth mechanism of aluminum oxide (Al2O3)
+in the early stages of the direct atomic layer deposition (ALD) on monolayer
+epitaxial graphene (EG) on silicon carbide (4H-SiC) has been investigated by
+atomic force microscopy (AFM) and Raman spectroscopy. Contrary to what is
+typically observed for other types of graphene, a large and uniform density of
+nucleation sites was observed in the case of EG and ascribed to the presence of
+the buffer layer at EG/SiC interface. The deposition process was characterized
+by Al2O3 island growth in the very early stages, followed by the formation of a
+continuous Al2O3 film (2.4 nm thick) after only 40 ALD cycles due to the
+islands coalescence, and subsequent layer-by-layer growth. Raman spectroscopy
+analyses showed low impact of the ALD process on the defects density and doping
+of EG. The EG strain was also almost unaffected by the deposition in the regime
+of island growth and coalescence, whereas a significant increase was observed
+after the formation of a compact Al2O3 film. The obtained results can have
+important implications for device applications of epitaxial graphene requiring
+the integration of ultra-thin high-k insulators.",2007.14427v1
+2020-07-29,High temperature mechanical properties and microstructure of hard TaSiN coatings,"Room and high temperature mechanical properties of reactive magnetron
+sputtered TaSiN coatings were measured using nanoindentation (between 25C and
+500C). Fracture toughness was also evaluated at a similar temperature range
+using the micropillar splitting method. The influence of the nitrogen
+concentration on the evolving phases and microstructure of the TaSiN coatings,
+before and after the high temperature testing, were examined by X-ray
+diffraction (XRD) and transmission electron microscopy (TEM) analysis. XRD
+spectra showed broad peaks with hexagonal $\gamma$-Ta2N as the main phase, with
+the cubic $\delta$-TaN phase emerging for higher N contents. Phase composition
+remained unchanged before and after the 500C tests. However, after the high
+temperature tests, TEM analysis showed the presence of an oxide surface layer,
+with a thickness that decreased (from 42 to 15 nm) with N content, due to
+residual oxygen diffusion, which replaces nitrogen to form amorphous SiOx.
+Beneath the oxide-rich surface layer, coatings exhibited a stable
+nanocrystalline columnar microstructure. Hardness and fracture toughness
+increased with N content, initially due to the formation of an amorphous Si-N
+tissue at grain boundaries, and for even higher N contents, due to the
+appearance of the hard cubic $\delta$-TaN phase. Hardness at 500C decreased
+only by 15%, while fracture toughness followed the opposite trend, due to
+increased plasticity with temperature. The optimum composition turned out to be
+Ta55Si10N35, which retained a hardness of 30 GPa at 500C, being also the
+toughest. These observations make this system very interesting for high
+temperature applications.",2007.14693v1
+2013-08-07,Intrinsic electron-glass effects in strongly-localized thallium-oxide films,"Transport measurements made on films of thallium-oxide (n-type semiconductor)
+are presented and discussed. The focus in this work is on the
+strongly-localized regime where charge transport is by variable-range-hopping.
+It is demonstrated that, at liquid-helium temperatures, these films exhibit all
+the characteristic features of intrinsic electron-glasses. These include a slow
+(logarithmic in time) conductance-relaxation that may be induced by any of the
+following protocols: Quench-cooling from high temperatures, sudden change of
+gate-voltage, exposure to infrared radiation, and stressing the system with a
+non-Ohmic field. The microstructure of the films are characterized by electron
+microscopy and their carrier-concentration are measured by Hall effect.
+Field-effect experiments reveal a memory-dip that has a width compatible with
+the carrier-concentration of the system as compared with previously studied
+electron-glasses. It is observed that the common ingredient in all the systems
+that exhibit electron-glass effects is high carrier-concentration suggesting
+that their localized sites may be multi-occupied even when deep into the
+insulating regime. That lightly-doped semiconductors do not show intrinsic
+electron-glass effects is consistent with this empirical observation. The
+connection between the memory-dip and the Coulomb-gap is discussed in light of
+these findings.",1308.1601v1
+2013-08-15,How Channel Segregates Originates: The Flow of Accumulated Impurity Clusters in Solidifying Steels,"The phenomenon, channel segregates (CS) as a result of gravity-driven flow
+due to density contrast occurred in the solid-liquid mushy zones1during
+solidification, often causes the severe destruction of homogeneity and even
+some fatal damages. Investigation on its mechanism sheds light on the
+understanding and controlling of the formation of solidifying metals,earth's
+core, igneous rock and sea ice. Until now, it still remains controversial what
+composes the density contrasts and, to what extent, how it affects channel
+segregates. Here, we show that in experimental 500kg and 100 ton commercial
+cast steel ingots CS originates from oxide Al2O3/MnS impurity clusters (OICs)
+initially nucleated from the oxide (Al2O3) particles, which induce an extra
+flow due to sharp density contrast between clusters and melt. The results
+uncover that, as OICs enrich and grow, their driven flow becomes stronger than
+the traditionally recognized inter-dendritic thermo-solutal convection,
+dominating the subsequent opening of the channels. This study extends the
+classical macrosegregation theory, highlights a significant technological
+breakthrough to control CS, and could quickly yield practical benefits to the
+worldwide manufacture of over 50 million tons of ingots, super-thick slab and
+heavy castings annually, as well as has general implications for the
+elaboration of other related natural phenomena.",1308.3344v1
+2013-08-16,"Towards time-dependent, non-equilibrium charge-transfer force fields: Contact electrification and history-dependent dissociation limits","Force fields uniquely assign interatomic forces for a given set of atomic
+coordinates. The underlying assumption is that electrons are in their
+quantum-mechanical ground state or in thermal equilibrium. However, there is an
+abundance of cases where this is unjustified because the system is only locally
+in equilibrium. In particular, the fractional charges of atoms, clusters, or
+solids tend to not only depend on atomic positions but also on how the system
+reached its state. For example, the charge of an isolated solid -- and thus the
+forces between atoms in that solid -- usually depends on the counterbody with
+which it has last formed contact. Similarly, the charge of an atom, resulting
+from the dissociation of a molecule, can differ for different solvents in which
+the dissociation took place. In this paper we demonstrate that such
+charge-transfer history effects can be accounted for by assigning discrete
+oxidation states to atoms. With our method, an atom can donate an integer
+charge to another, nearby atom to change its oxidation state as in a redox
+reaction. In addition to integer charges, atoms can exchange ""partial charges""
+which are determined with the split charge equilibration method.",1308.3573v1
+2014-03-03,Quasiparticle dynamics and spin-orbital texture of the SrTiO3 two-dimensional electron gas,"Two-dimensional electron gases (2DEGs) in SrTiO$_3$ have become model systems
+for engineering emergent behaviour in complex transition metal oxides.
+Understanding the collective interactions that enable this, however, has thus
+far proved elusive. Here we demonstrate that angle-resolved photoemission can
+directly image the quasiparticle dynamics of the $d$-electron subband ladder of
+this complex-oxide 2DEG. Combined with realistic tight-binding supercell
+calculations, we uncover how quantum confinement and inversion symmetry
+breaking collectively tune the delicate interplay of charge, spin, orbital, and
+lattice degrees of freedom in this system. We reveal how they lead to
+pronounced orbital ordering, mediate an orbitally-enhanced Rashba splitting
+with complex subband-dependent spin-orbital textures and markedly change the
+character of electron-phonon coupling, co-operatively shaping the low-energy
+electronic structure of the 2DEG. Our results allow for a unified understanding
+of spectroscopic and transport measurements across different classes of
+SrTiO$_3$-based 2DEGs, and yield new microscopic insights on their functional
+properties.",1403.0520v2
+2016-11-17,Hydrogen plasma exposure of In/ITO bilayers as an effective way for dispersing In nanoparticles,"We address the production of indium nanoparticles (In NPs) from In thin films
+thermally evaporated on both c-Si substrates and sputtered indium tin oxide
+(ITO) as well as from sputtered ITO thin films, exposed to a hydrogen (H2)
+plasma. On the one hand, we show that evaporated In thin films grow in
+Volmer-Weber (VW) mode; H2 plasma reduces their surface oxide and substrate
+annealing reshapes them from flat islands into spheres, without any remarkable
+surface migration or coalescence. On the other hand, we studied the In NPs
+formation on the ITO thin films and on In/ITO bilayer structures, by varying
+the H2 plasma exposure time and the substrate temperature. This led us to
+postulate that the main role of H2 plasma is to release In atoms from ITO
+surface. At low substrate temperature (100{\deg}C), In NPs grow on ITO surface
+via a solid phase VW mode, similar to evaporated In thin films, while at
+300{\deg}C, small In droplets preferentially nucleate along the ITO grain
+boundaries where ITO reduction rate and atomic diffusion coefficient are higher
+compared with the ITO grain surface. As the droplets grow larger and connect
+with each other, larger ones (1-2 um microns) are suddenly formed based on a
+liquid phase growth-connection-coalescence process. This phenomenon is even
+stronger in the case of In/ITO bilayer where the large In drops resulting from
+the evaporated In connect with the smaller NPs resulting from ITO reduction and
+rapidly merge into very large NPs (15 um)",1611.05606v2
+2017-01-15,Programmable Molecular Composites of Tandem Proteins with Graphene-Oxide for Efficient Bimoprh Actuators,"The rapid expansion in the spectrum of two-dimensional (2D) materials has
+driven the efforts of research on the fabrication of 2D composites and
+heterostructures. Highly ordered structure of 2D materials provides an
+excellent platform for controlling the ultimate structure and properties of the
+composite material with precision. However, limited control over the structure
+of the adherent material and its interactions with highly ordered 2D materials
+results in defective composites with inferior performance. Here, we demonstrate
+the successful synthesis, integration, and characterization of hybrid 2D
+material systems consisting of tandem repeat (TR) proteins inspired by squid
+ring teeth and graphene oxide (GO). The TR protein layer acts as a unique
+programmable molecular spacer between GO layers. As an application, we further
+demonstrate thermal actuation using bimorph molecular composite films. Bimorph
+actuators made of molecular composite films (GO/TR) can lead to energy
+efficiencies 18 times higher than regular bimorph actuators consisting of a GO
+layer and a TR protein layer (i.e., conventional bulk composite of GO and TR).
+Additionally, molecular composite bimorph actuators can reach curvature values
+as high as 1.2 cm-1 by using TR proteins with higher molecular weight, which is
+3 times higher than conventional GO and TR composites.",1701.04019v1
+2017-01-19,Ultrafast Electron-Lattice Coupling Dynamics in VO2 and V2O3 Thin Films,"Ultrafast optical pump - optical probe and optical pump - terahertz probe
+spectroscopy were performed on vanadium dioxide (VO2) and vanadium sesquioxide
+(V2O3) thin films over a wide temperature range. A comparison of the
+experimental data from these two different techniques and two different
+vanadium oxides, in particular a comparison of the electronic oscillations
+generated by the photoinduced longitudinal acoustic modulation, reveals the
+strong electron-phonon coupling that exists in the metallic state of both
+materials. The low energy Drude response of V2O3 appears more susceptible than
+VO2 to ultrafast strain control. Additionally, our results provide a
+measurement of the temperature dependence of the sound velocity in both
+systems, revealing a four- to fivefold increase in VO2 and a three- to fivefold
+increase in V2O3 across the phase transition. Our data also confirm
+observations of strong damping and phonon anharmonicity in the metallic phase
+of VO2, and suggest that a similar phenomenon might be at play in the metallic
+phase of V2O3. More generally, our simple table-top approach provides relevant
+and detailed information about dynamical lattice properties of vanadium oxides,
+opening the way to similar studies in other complex materials.",1701.05531v1
+2017-04-23,Steep-slope Hysteresis-free Negative Capacitance MoS2 Transistors,"The so-called Boltzmann Tyranny defines the fundamental thermionic limit of
+the subthreshold slope (SS) of a metal-oxide-semiconductor field-effect
+transistor (MOSFET) at 60 mV/dec at room temperature and, therefore, precludes
+the lowering of the supply voltage and the overall power consumption. Adding a
+ferroelectric negative capacitor to the gate stack of a MOSFET may offer a
+promising solution to bypassing this fundamental barrier. Meanwhile,
+two-dimensional (2D) semiconductors, such as atomically thin transition metal
+dichalcogenides (TMDs) due to their low dielectric constant, and ease of
+integration in a junctionless transistor topology, offer enhanced electrostatic
+control of the channel. Here, we combine these two advantages and demonstrate
+for the first time a molybdenum disulfide (MoS2) 2D steep slope transistor with
+a ferroelectric hafnium zirconium oxide layer (HZO) in the gate dielectric
+stack. This device exhibits excellent performance in both on- and off-states,
+with maximum drain current of 510 {\mu}A/{\mu}m, sub-thermionic subthreshold
+slope and is essentially hysteresis-free. Negative differential resistance
+(NDR) was observed at room temperature in the MoS2 negative capacitance
+field-effect-transistors (NC-FETs) as the result of negative capacitance due to
+the negative drain-induced-barrier-lowering (DIBL). High on-current induced
+self-heating effect was also observed and studied.",1704.06865v2
+2018-05-14,Structural Dependence of Chemical Durability in Modified Aluminoborate Glasses,"Alkali and alkaline earth aluminoborate glasses feature high resistance to
+cracking under sharp contact loading compared to other oxide glasses. However,
+due to the high content of hygroscopic B2O3, it is expected that applications
+of these glasses could be hindered by poor chemical durability in aqueous
+solutions. Indeed, the compositional and structural dependence of their
+dissolution kinetics remains unexplored. In this work, we correlate the
+dissolution rates of aluminoborate glasses in acidic, neutral, and basic
+solutions with the structural changes induced by varying the aluminum-to-boron
+ratio. In detail, we investigate a total of seventeen magnesium, lithium, and
+sodium aluminoborate glasses with fixed modifier content of 25 mol%. We show
+that the structural changes induced by alumina depend on the network modifier.
+We also demonstrate a correlation between the chemical durability at various pH
+values and the structural changes in Mg-, Li- and Na- aluminoborate glasses.
+The substitution of alumina by boron oxide leads to a general decrease of
+chemical corrosion in neutral and acidic solutions. The lowest dissolution rate
+value is observed in Mg-aluminoborate glasses, as a consequence of the
+intermediate character of magnesium which can increase the network
+cross-linking. For basic solutions, the chemical durability is almost constant
+for the different amount of alumina in the three series, likely because B2O3 is
+susceptible to nucleophilic attack, which is favored in high-OH- solutions.",1805.05191v1
+2018-05-10,Reduced-Graphene-Oxide with Dispersed Au-Ir Nanoparticles as Active Support for Pt at low Loadding for Electrocatalytic Oxygen Electroreduction,"We report here on a novel and facile techniques for the synthesis
+nanocomposite based on stable bimetallic catalyst containing iridium and gold
+nanoparticles electrodeposited on chemically reduced graphene oxide (rGO) sheet
+admixed with platinum nanoparticles as an efficient electrocatalyst to
+facilitate the oxygen reduction reaction (ORR) in acidic medium. Raman
+spectroscopy, infrared spectroscopy (IR), scanning electron microscope (SEM),
+transmission electron microscope (TEM) methods were employed to characterize
+the rGO, Au-NPS-rGO, Ir-NPS-rGO, Au-Ir-rGO nanocomposites formed on the
+electrode surface. Here we present a comparative study into the relative
+effects of each hybrid nanocomposites: Au-NPS-rGO, Ir-NPS-rGO, Au-Ir-rGO
+nanocomposites on the performance of platinum nanoparticles towards the oxygen
+reduction reaction (ORR) in acidic media. For the purposes of comparing the
+supports, a simple platinum black catalyst is used and the performance
+isevaluated via direct measurement of peroxide by rotating ring-disk electrode
+(RRDE) to determine the number of electrons (n) transferred in the ORR. It was
+found that platinum nanoparticles dispersed within Au-Ir-rGO support follows a
+quasi 4-electron mechanism (3.99-4 electrons involved) due to that the ORR
+takes place mainly on the active Pt particles, and produced hydrogen peroxide
+is reduced at Au-Ir-rGO support.",1805.05458v1
+2018-05-10,Prussian Blue Modified Reduced Graphene Oxide as Support for Pt Nanoparticles: Development of Efficient Catalysts for Oxygen Electroreduction in Acid Medium,"Pt electrocatalytic nanoparticles were deposited onto hybrid carriers
+composed of reduced graphene oxide (rGO)-transition metal hexacyanoferrate
+(Prussian Blue-PB) and the resulting system's electrochemical activity was
+investigated during oxygen reduction reaction in acidic solution. The Prussian
+Blue -utilizing and Pt nanoparticle-containing materials were characterized
+using transmission electron microscopy, X-ray diffraction and electrochemical
+diagnostic techniques such as cyclic voltammetry and rotating ring-disk
+voltammetry. Application of rGO carriers modified with Prussian Blue as
+matrices (supports) for Pt catalytic centers does not change practically the
+potential of electroreduction of oxygen in 0.5 mol dm-3 H2SO4 (under rotating
+disk voltammetric conditions) relative to the behavior of the analogous PB-free
+system. What is even more important that, due to the presence of the
+polynuclear cyanoferrate modifier, the amounts of the undesirable hydrogen
+peroxide intermediate are significantly decreased (at ring in the rotating
+ring-disk voltammetry). The results are consistent with the bifunctional
+mechanism in which oxygen reduction is initiated at Pt centers and the hydrogen
+peroxide intermediate is reductively decomposed at reactive PB-modified rGO
+supports.",1805.05459v1
+2018-05-16,Electrically controlled water permeation through graphene oxide membranes,"Developing 'smart' membranes that allow precise and reversible control of
+molecular permeation using external stimuli would be of intense interest for
+many areas of science: from physics and chemistry to life-sciences. In
+particular, electrical control of water permeation through membranes is a
+long-sought objective and is of crucial importance for healthcare and related
+areas. Currently, such adjustable membranes are limited to the modulation of
+wetting of the membranes and controlled ion transport, but not the controlled
+mass flow of water. Despite intensive theoretical work yielding conflicting
+results, the experimental realisation of electrically controlled water
+permeation has not yet been achieved. Here we report electrically controlled
+water permeation through micrometre-thick graphene oxide (GO) membranes. By
+controllable electric breakdown, conductive filaments are created in the GO
+membrane. The electric field concentrated around such current carrying
+filaments leads to controllable ionisation of water molecules in graphene
+capillaries, allowing precise control of water permeation: from ultrafast
+permeation to complete blocking. Our work opens up an avenue for developing
+smart membrane technologies and can revolutionize the field of artificial
+biological systems, tissue engineering and filtration.",1805.06390v1
+2008-07-16,Emergence of Particle-Hole Symmetry near Optimal Doping in High-Temperature Copper Oxide Superconductors,"High-temperature copper oxide superconductors (cuprates) display
+unconventional physics when they are lightly doped whereas the standard theory
+of metals prevails in the opposite regime. For example, the thermoelectric
+power, that is the voltage that develops across a sample in response to a
+temperature gradient, changes sign abruptly near optimal doping in a wide class
+of cuprates, a stark departure from the standard theory of metals in which the
+thermopower vanishes only when one electron exists per site. We show that this
+effect arises from proximity to a state in which particle-hole symmetry is
+dynamically generated. The operative mechanism is dynamical spectral weight
+transfer from states that lie at least 2eV away from the chemical potential. We
+show that the sign change is reproduced quantitatively within the Hubbard model
+for moderate values of the on-site repulsion, $U$. For sufficiently large
+values of on-site repulsion, for example, $U=20t$, ($t$ the hopping matrix
+element), dynamical spectral weight transfer attenuates and our calculated
+results for the thermopower are in prefect agreement with exact atomic limit.
+The emergent particle-hole symmetry close to optimal doping points to pairing
+in the cuprates being driven by high-energy electronic states.",0807.2854v3
+2009-12-08,Effect of the nature of alkali and alkaline-earth oxides on the structure and crystallization of an aluminoborosilicate glass developed to immobilize highly concentrated nuclear waste solutions,"A complex rare-earth rich aluminoborosilicate glass has been proved to be a
+good candidate for the immobilization of new high level radioactive wastes. A
+simplified seven-oxides composition of this glass was selected for this study.
+In this system, sodium and calcium cations were supposed in other works to
+simulate respectively all the other alkali (R+=Li+, Rb+, Cs+) and
+alkaline-earth (R'2+=Sr2+, Ba2+) cations present in the complex glass
+composition. Moreover, neodymium or lanthanum are used here to simulate all the
+rare-earths and actinides occurring in waste solutions. In order to study the
+impact of the nature of R+ and R'2+ cations on both glass structure and melt
+crystallization tendency during cooling, two glass series were prepared by
+replacing either Na+ or Ca2+ cations in the simplified glass by respectively
+(Li+, K+, Rb+, Cs+) or (Mg2+, Sr2+, Ba2+) cations. From these substitutions, it
+was established that alkali ions are preferentially involved in the charge
+compensation of (AlO4)- entities in the glass network comparatively to
+alkaline-earth ions. The glass compositions containing calcium give way to the
+crystallization of an apatite silicate phase bearing calcium and rare-earth
+ions. The melt crystallization tendency during cooling strongly varies with the
+nature of the alkaline-earth.",0912.1576v1
+2011-11-04,Study of X-ray Radiation Damage in Silicon Sensors,"The European X-ray Free Electron Laser (XFEL) will deliver 30,000 fully
+coherent, high brilliance X-ray pulses per second each with a duration below
+100 fs. This will allow the recording of diffraction patterns of single complex
+molecules and the study of ultra-fast processes. Silicon pixel sensors will be
+used to record the diffraction images. In 3 years of operation the sensors will
+be exposed to doses of up to 1 GGy of 12 keV X-rays. At this X-ray energy no
+bulk damage in silicon is expected. However fixed oxide charges in the
+insulating layer covering the silicon and interface traps at the Si-SiO2
+interface will be introduced by the irradiation and build up over time.
+  We have investigated the microscopic defects in test structures and the
+macroscopic electrical properties of segmented detectors as a function of the
+X-ray dose. From the test structures we determine the oxide charge density and
+the densities of interface traps as a function of dose. We find that both
+saturate (and even decrease) for doses between 10 and 100 MGy. For segmented
+sensors the defects introduced by the X-rays increase the full depletion
+voltage, the surface leakage current and the inter-pixel capacitance. We
+observe that an electron accumulation layer forms at the Si-SiO2 interface. Its
+width increases with dose and decreases with applied bias voltage. Using TCAD
+simulations with the dose dependent parameters obtained from the test
+structures, we are able to reproduce the observed results. This allows us to
+optimize the sensor design for the XFEL requirements.",1111.1180v1
+2012-01-07,Ni coarsening in the three-phase solid oxide fuel cell anode - a phase-field simulation study,"Ni coarsening in Ni-yttria stabilized zirconia (YSZ) solid oxide fuel cell
+anodes is considered a major reason for anode degradation. We present a
+predictive, quantative modeling framework based on the phase-field approach to
+systematically examine coarsening kinetics in such anodes. The initial
+structures for simulations are experimentally acquired functional layers of
+anodes. Sample size effects and error analysis of contact angles are examined.
+Three phase boundary (TPB) lengths and Ni surface areas are quantatively
+identified on the basis of the active, dead-end, and isolated phase clusters
+throughout coarsening. Tortuosity evolution of the pores is also investigated.
+We find that phase clusters with larger characteristic length evolve slower
+than those with smaller length scales. As a result, coarsening has small
+positive effects on transport, and impacts less on the active Ni surface area
+than the total counter part. TPBs, however, are found to be sensitive to local
+morphological features and are only indirectly correlated to the evolution
+kinetics of the Ni phase.",1201.1567v1
+2013-08-31,An electrical conductivity relaxation study of oxygen transport in samarium doped ceria,"The efficacy of the electrical conductivity relaxation (ECR) technique for
+investigating the oxygen transport properties of mixed conducting oxides has
+been evaluated. Fifteen mol% samarium doped ceria (SDC15), for which
+approximate values of the two principal transport properties, bulk oxygen
+diffusivity, $D_{Chem}$, and surface reaction rate constant, $k_S$, can be
+found in the literature, was chosen as the benchmark material against which to
+validate the methodology. Measurements were carried out at temperatures between
+750 $^\circ$C and 850 $^\circ$C and over a wide range of oxygen partial
+pressures. An unexpectedly high p-type electronic transference number enabled
+ECR measurements under oxidizing conditions. A systematic data analysis
+procedure was developed to permit reliable extraction of the kinetic parameters
+even in the general case of simultaneous bulk and surface limitation. The
+$D_{Chem}$ from this study showed excellent qualitative and quantitative
+agreement with expected values, falling in the range from $\sim 2\times10^{-5}$
+to $2\times10^{-4}$ cm$^2$/s. The surface reaction constant under H$_2$/H$_2$O
+mixtures also showed good agreement with literature results. Remarkably, this
+value increased by a factor of 40 under mixtures of CO/CO$_2$ or O$_2$/Ar. This
+observation suggests kinetic advantages for production of CO rather than H$_2$
+in a two-step solar-driven thermochemical process based on samarium doped
+ceria.",1309.0064v2
+2013-09-01,Xe anions in stable Mg-Xe compounds: the mechanism of missing Xe in earth atmosphere,"The reactivity of noble gas elements is important for both fundamental
+chemistry and geological science. The discovery of the oxidation of Xe extended
+the doctrinal boundary of chemistry that a complete shell is inert to reaction.
+The oxidations of Xe by various geological substances have been researched in
+order to explain the missing Xe in earth atmosphere. Among many proposals, the
+chemistry mechanisms are straightforward as they identify chemical processes
+that can capture Xe in earth interior. However, all the mechanisms based on
+current noble gas chemistry face the same difficulty: the earth lower mantle
+and core are rich in metals and therefore their chemical environment is
+reductive. On the other hand, up till now, the opposite chemical inclination,
+the reductive propensity, i.e. gaining electrons and forming anions, has not
+been proposed and examined for noble gas elements. In this work, we
+demonstrate, using first principles calculations and an efficient structure
+prediction method, that Xe and Kr can form stable MgXe and MgKr compounds under
+high pressure. These compounds are intermetallic and Xe or Kr is negatively
+charged. We also find that elevated temperature has large effect in stabilizing
+MgXe and MgKr compounds. Our results show that the earth has the capability of
+capturing Xe but not Kr, which is consistent to the depletion of Xe in earth
+atmosphere. The stability of these compounds suggests that chemical species
+with completely filled shell may still gain more electrons filling their outer
+shell in chemical reactions.",1309.0696v2
+2013-09-04,Splashing phenomena of room temperature liquid metal droplet striking on the pool of the same liquid under ambient air environment,"In this article, the fluid dynamics of room temperature liquid metal (RTLM)
+droplet impacting onto a pool of the same liquid in ambient air was
+investigated. A series of experiments were conducted in order to disclose the
+influence of the oxidation effect on the impact dynamics. The droplet shape and
+impact phenomenology were recorded with the aid of a high-speed digital camera.
+The impact energy stored in the splash structures was estimated via a
+theoretical model and several morphological parameters obtained from
+instantaneous images of the splash. It was observed that the droplet shape and
+the splashing morphology of RTLM were drastically different from those of
+water, so was the impact dynamics between room temperature LM pool and high
+temperature LM pool. The energy analysis disclosed that the height of the jet
+is highly sensitive to the viscosity of the fluid, which is subjected to the
+oxidation effect and temperature effect simultaneously, and thus perfectly
+explained the phenomena. These basic findings are important for the application
+of RTLM in a series of newly emerging technologies such as liquid metal based
+spray cooling, ink-jet printed electronics, interface material painting and
+coating, metallurgy, and 3D packages, etc.",1309.1075v1
+2013-09-23,Polaron dynamics and decoherence in an interacting two-spin system coupled to optical phonon environment,"We study two anisotropically interacting spins coupled to optical phonons; we
+restrict our analysis to the regime of strong coupling to the environment, to
+the antiadiabatic region, and to the subspace with zero value for $S^z_T$ (the
+z-component of the total spin). In the case where each spin is coupled to a
+different phonon bath, we assume that the system and the environment are
+initially uncorrelated (and form a simply separable state) in the polaronic
+frame of reference. By analyzing the {polaron} dynamics through non-Markovian
+quantum master equation, we find that the system manifests a small amount of
+decoherence that decreases both with increasing non-adiabaticity and with
+enhancing strength of coupling; whereas, under the Markovian approximation, the
+polaronic system exhibits a decoherence free behavior. For the situation where
+both spins are coupled to the same phonon bath, we also show that the system is
+decoherence free in the subspace where $S^z_T$ is fixed. To suppress
+decoherence through quantum control, we employ a train of pi pulses and
+demonstrate that unitary evolution of the system can be retained. We propose
+realization of a weakly decohering charge qubit from an electron in an
+oxide-based (tunnel-coupled) double quantum dot system.",1309.5824v3
+2014-05-13,"Energetics, structure, and composition of nanoclusters in Oxide Dispersion Strengthened Fe-Cr alloys","Extensive first-principle calculations on embedded clusters containing few O,
+Y, Ti, and Cr atoms as well as vacancies are performed to obtain interaction
+parameters to be applied in Metropolis Monte Carlo simulations, within the
+framework of a rigid lattice model. A novel description using both pair and
+triple parameters is shown to be more precise than the commonly used pair
+parameterization. Simulated annealing provides comprehensive data on the
+energetics, structure and stoichiometry of nm-size clusters at T=0. The results
+are fully consistent with the experimental finding of negligible coarsening and
+a high dispersion of the clusters, with the observation that the presence of Ti
+reduces the cluster size, and with the reported radiation tolerance of the
+clusters. In alloys without vacancies clusters show a planar structure, whereas
+the presence of vacancies leads to three-dimensional configurations.
+Additionally, Metropolis Monte Carlo simulations are carried out at high
+temperature in order to investigate the dependence of nanocluster composition
+on temperature. A good agreement between the existing experimental data on the
+ratios (Y+Ti):O, Y:Ti, (Y+Cr):O, and Y:Cr, and the simulation results is found.
+In some cases it is even possible to draw the conclusion that the respective
+alloys contained a certain amount of vacancies, and that the clusters analyzed
+were frozen-in high-temperature configurations. The comparison of experimental
+data with those obtained by simulations demonstrates that the assumption of
+nanoclusters consisting of nonstoichiometric oxides which are essentially
+coherent with the bcc lattice of the Fe-Cr matrix leads to reasonable results.",1405.3041v1
+2014-05-19,On the roles of graphene oxide doping for enhanced supercurrent in MgB2 based superconductors,"Due to their graphene-like properties after oxygen reduction, incorporation
+of graphene oxide (GO) sheets into correlated-electron materials offers a new
+pathway for tailoring their properties. Fabricating GO nanocomposites with
+polycrystalline MgB2 superconductors leads to an order of magnitude enhancement
+of the supercurrent at 5 K/8 T and 20 K/4 T. Herein, we introduce a novel
+experimental approach to overcome the formidable challenge of performing
+quantitative microscopy and microanalysis of such composites, so as to unveil
+how GO doping influences the structure and hence the material properties. Atom
+probe microscopy and electron microscopy were used to directly image the GO
+within the MgB2, and we combined these data with computational simulations to
+derive the property-enhancing mechanisms. Our results reveal synergetic effects
+of GO, namely, via localized atomic (carbon and oxygen) doping as well as
+texturing of the crystals, which provide both inter and intra granular flux
+pinning. This study opens up new insights into how low-dimensional
+nanostructures can be integrated into composites to modify the overall
+properties, using a methodology amenable to a wide range of applications.",1405.4619v1
+2016-05-03,Valence band electronic structure evolution of graphene oxide upon thermal annealing for optoelectronics,"We report valence band electronic structure evolution of graphene oxide (GO)
+upon its thermal reduction. Degree of oxygen functionalization was controlled
+by annealing temperatures, and an electronic structure evolution was monitored
+using real-time ultraviolet photoelectron spectroscopy. We observed a drastic
+increase in density of states around the Fermi level upon thermal annealing at
+~600 oC. The result indicates that while there is an apparent band gap for GO
+prior to a thermal reduction, the gap closes after an annealing around that
+temperature. This trend of band gap closure was correlated with electrical,
+chemical, and structural properties to determine a set of GO material
+properties that is optimal for optoelectronics. The results revealed that
+annealing at a temperature of ~500 oC leads to the desired properties,
+demonstrated by a uniform and an order of magnitude enhanced photocurrent map
+of an individual GO sheet compared to as-synthesized counterpart.",1605.01048v1
+2016-08-02,Correlation of Fe-based Superconductivity and Electron-Phonon Coupling in an FeAs/Oxide Heterostructure,"Interfacial phonons between iron-based superconductors (FeSCs) and perovskite
+substrates have received considerable attention due to the possibility of
+enhancing preexisting superconductivity. Using scanning tunneling spectroscopy,
+we studied the correlation between superconductivity and e-ph interaction with
+interfacial-phonons in an iron-based superconductor Sr$_2$VO$_3$FeAs ($T_c
+\approx$ 33 K) made of alternating FeSC and oxide layers. The quasiparticle
+interference measurement over regions with systematically different average
+superconducting gaps due to the e-ph coupling locally modulated by O vacancies
+in VO$_2$ layer, and supporting self-consistent momentum-dependent Eliashberg
+calculations provide a unique real-space evidence of the forward-scattering
+interfacial phonon contribution to the total superconducting pairing.",1608.00886v4
+2016-08-08,"On the Multi-Reference Nature of Plutonium Oxides: PuO$_2^{2+}$, PuO$_2$, PuO$_3$ and PuO$_2$(OH)$_2$","Actinide-containing complexes present formidable challenges for electronic
+structure methods due to the large number of degenerate or quasi-degenerate
+electronic states arising from partially occupied 5f and 6d shells.
+Conventional multi-reference methods can treat active spaces that are often at
+the upper limit of what is required for a proper treatment of species with
+complex electronic structures, leaving no room for verifying their suitability.
+In this work we address the issue of properly defining the active spaces in
+such calculations, and introduce a protocol to determine optimal active spaces
+based on the use of the Density Matrix Renormalization Group algorithm and
+concepts of quantum information theory. We apply the protocol to elucidate the
+electronic structure and bonding mechanism of volatile plutonium oxides
+(PuO$_3$ and PuO$_2$(OH)$_2$), species associated with nuclear safety issues
+for which little is known about the electronic structure and energetics. We
+show how, within a scalar relativistic framework, orbital-pair correlations can
+be used to guide the definition of optimal active spaces which provide an
+accurate description of static/non-dynamic electron correlation, as well as to
+analyse the chemical bonding beyond a simple orbital model. From this bonding
+analysis we are able to show that the addition of oxo- or hydroxo-groups to the
+plutonium dioxide species considerably changes the pi-bonding mechanism with
+respect to the bare triatomics, resulting in bent structures with considerable
+multi-reference character.",1608.02353v1
+2016-08-12,Enhanced charge ordering transition in doped CaFeO3 through steric templating,"We report density functional theory (DFT) investigation of $B$-site doped
+CaFeO$_3$, a prototypical charge-ordered perovskite. At 290 K, CaFeO$_3$
+undergoes a metal-insulator transition and a charge disproportionation reaction
+2Fe$^{4+}$$\rightarrow$Fe$^{5+}$+Fe$^{3+}$. We observe that when Zr dopants
+occupy a (001) layer, the band gap of the resulting solid solution increases to
+0.93 eV due to a 2D Jahn-Teller type distortion, where FeO$_6$ cages on the
+$xy$ plane elongate along $x$ and $y$ alternatively between neighboring Fe
+sites. Furthermore, we show that the rock-salt ordering of the Fe$^{5+}$ and
+Fe$^{3+}$ cations can be enhanced when the $B$-site dopants are arranged in a
+(111) plane due to a collective steric effect that facilitates the size
+discrepancy between the Fe$^{5+}$O$_6$ and Fe$^{3+}$O$_6$ octahedra and
+therefore gives rise to a larger band gap. The enhanced charge
+disproportionation in these solid solutions is verified by rigorously
+calculating the oxidation states of the Fe cations with different octahedral
+cage sizes. We therefore predict that the corresponding transition temperature
+will increase due to the enhanced charge ordering and larger band gap. The
+compositional, structural and electrical relationships exploited in this paper
+can be extended to a variety of perovskites and non-perovskite oxides providing
+guidance in structurally manipulating electrical properties of functional
+materials.",1608.03761v1
+2016-08-21,A study on the growth mechanism and the process parameters controlling aluminum oxide thin films deposition by pulsed pressure MOCVD,"Aluminum oxide thin films were deposited on silicon substrates under
+different deposition conditions using pulse pressure metal organic chemical
+vapour deposition (PP-MOCVD). The current study investigates into the growth
+mechanism of the deposited film and the control of the film morphology by
+varying the processing parameters of PP-MOCVD - choice of solvent,
+concentration, and presence of a shield. Aluminum sec-butoxide (ASB) was used
+as the aluminum source while hexane and toluene were used as the solvents. The
+films were deposited at 475oC at different precursor concentrations. It was
+observed that the choice of solvent has no effect on the surface morphology,
+but it influenced the deposition rate. The improved deposition rate, relatively
+close enthalpy of vaporisation ({\Delta}H) values and uniformity of the film,
+irrespective of the growth conditions, showed that hexane was a better solvent
+for ASB than toluene. A hybrid mode of vapour deposition and vapour
+condensation model for thin film growth is proposed where five different
+mechanisms lead to a solid film formation. These include vapour phase
+deposition under low arrival rate, vapour phase deposition under high arrival
+rate, Leidenfrost aerosol formation, heterogeneous particle formation and
+liquid droplet impingement. The important parameter that needs to be controlled
+is the precursor flux arrival rate which can be controlled by varying the
+precursor concentration, use of a solvent with a low {\Delta}H and the presence
+of a shield over the substrate, which influences the surface morphology and the
+growth rate of the films.",1608.05892v1
+2016-12-02,Reactors as a source of antineutrinos: the effect of fuel loading and burnup for mixed oxide fuels,"In a conventional light water reactor loaded with a range of uranium and
+plutonium-based fuel mixtures, the variation in antineutrino production over
+the cycle reflects both the initial core fissile inventory and its evolution.
+Under the assumption of constant thermal power, we calculate the rate at which
+antineutrinos are emitted from variously fueled cores, and the evolution of
+that rate as measured by a representative ton-scale antineutrino detector. We
+find that antineutrino flux decreases with burnup for Low Enriched Uranium
+cores, increases for full mixed-oxide (MOX) cores, and does not appreciably
+change for cores with a MOX fraction of approximately 75%. Accounting for
+uncertainties in the fission yields, in the emitted antineutrino spectra, and
+the detector response function, we show that the difference in core-wide MOX
+fractions at least as small as 8% can be distinguished using a hypothesis test.
+The test compares the evolution of the antineutrino rate relative to an initial
+value over part or all of the cycle. The use of relative rates reduces the
+sensitivity of the test to an independent thermal power measurement, making the
+result more robust against possible countermeasures. This rate-only approach
+also offers the potential advantage of reducing the cost and complexity of the
+antineutrino detectors used to verify the diversion, compared to methods that
+depend on the use of the antineutrino spectrum. A possible application is the
+verification of the disposition of surplus plutonium in nuclear reactors.",1612.00540v2
+2016-12-27,Annealing shallow Si/SiO$_2$ interface traps in electron-beam irradiated high-mobility metal-oxide-silicon transistors,"Electron-beam (e-beam) lithography is commonly used in fabricating
+metal-oxide-silicon (MOS) quantum devices but creates defects at the Si/SiO$_2$
+interface. Here we show that a forming gas anneal is effective at removing
+shallow defects ($\leq$ 4 meV below the conduction band edge) created by an
+e-beam exposure by measuring the density of shallow electron traps in two sets
+of high-mobility MOS field-effect transistors (MOSFETs). One set was irradiated
+with an electron-beam (10 keV, 40 $\mu$C/cm$^2$) and was subsequently annealed
+in forming gas while the other set remained unexposed. Low temperature (335 mK)
+transport measurements indicate that the forming gas anneal recovers the e-beam
+exposed sample's peak mobility (14,000 cm$^2$/Vs) to within a factor of two of
+the unexposed sample's mobility (23,000 cm$^2$/Vs). Using electron spin
+resonance (ESR) to measure the density of shallow traps, we find that the two
+sets of devices are nearly identical, indicating the forming gas anneal is
+sufficient to anneal out shallow defects generated by the e-beam exposure.
+Fitting the two sets of devices' transport data to a percolation transition
+model, we extract a T=0 percolation threshold density in quantitative agreement
+with our lowest temperature ESR-measured trap densities.",1612.08729v2
+2017-06-13,Tribopolymer Formation Mechanism on the RuO$_2$(110) Surface,"Tribopolymer formed on the contacts of microelectromechanical and
+nanoelectromechanical system (MEMS/NEMS) devices is a major concern hampering
+their practical use in information technology. Conductive metal oxides, such as
+RuO$_2$ and ReO$_3$, have been regarded as promising candidate materials for
+MEMS/NEMS contacts due to their conductivity, hardness, and relatively
+chemically inert surfaces. However, recent experimental works demonstrate that
+trace amounts of polymer could still form on RuO$_2$ surfaces. In this study,
+we demonstrate the mechanism of this class of unexpected tribopolymer formation
+by conducting density functional theory based computational compression
+experiments with benzene as the contamination gas. First, mechanical force
+during compression changes the benzene molecules from slightly physisorbed to
+strongly chemisorbed. Further compression causes deformation and chemical
+linkage of the benzene molecules. Finally, the two contacts detach, with one
+having a complex organic molecule attached and the other with a more reactive
+surface. The complex organic molecule, which has an oxabicyclic segment, can be
+viewed as the rudiment of tribopolymer, and the more reactive surface can
+trigger the next adsorption--reaction--tribopolymer formation cycle. Based on
+these results, we also predict tribopolymer formation rates by using
+transition--state theory and the second--order rate law. This study deepens our
+understanding of tribopolymer formation (especially on metal oxides) and
+provides strategies for suppressing tribopolymerization.",1706.04096v1
+2017-06-19,Insights on the mechanism of water-alcohol separation in multilayer graphene oxide membranes: entropic versus enthalpic factors,"Experimental evidences have shown that graphene oxide (GO) can be impermeable
+to liquids, vapors and gases, while it allows a fast permeation of water
+molecules. The understanding of filtration mechanisms came mostly from studies
+dedicated to water desalination, while very few works have been dedicated to
+distilling alcohols. In this work, we have investigated the molecular level
+mechanism underlying the alcohol/water separation inside GO membranes. A series
+of molecular dynamics and Grand-Canonical Monte Carlo simulations were carried
+out to probe the ethanol/water and methanol/water separation through GO
+membranes composed of multiple layered graphene-based sheets with different
+interlayer distance values and number of oxygen-containing functional groups.
+Our results show that the size exclusion and membrane affinities are not
+sufficient to explain the selectivity. Besides that, the favorable water
+molecular arrangement inside GO 2D-channels forming a robust H-bond network and
+the fast water diffusion are crucial for an effective separation mechanism. In
+other words, the separation phenomenon is not only governed by affinities with
+the membrane (enthalpic mechanisms) but mainly by the geometry and size factors
+(entropic mechanisms). We verified that the 2D geometry channel with optimal
+interlayer distance are key factors for designing more efficient alcohol-water
+separation membranes. Our findings are consistent with the available
+experimental data and contribute to clarify important aspects of the separation
+behavior of confined alcohol/water in GO membranes.",1706.06213v1
+2017-06-26,Oxide-mediated self-limiting recovery of field effect mobility in plasma-treated MoS$_2$,"Precise tunability of electronic properties of 2D nanomaterials is a key goal
+of current research in this field of materials science. Chemical modification
+of layered transition metal dichalcogenides leads to the creation of
+heterostructures of low-dimensional variants of these materials. In particular,
+the effect of oxygen-containing plasma treatment on molybdenum disulfide
+(MoS$_2$) has long been thought to be detrimental to the electrical performance
+of the material. Here we show that the mobility and conductivity of MoS$_2$ can
+be precisely controlled and improved by systematic exposure to oxygen:argon
+plasma, and characterise the material utilising advanced spectroscopy and
+microscopy. Through complementary theoretical modelling which confirms
+conductivity enhancement, we uncover the role of a two-dimensional phase of
+molybdenum trioxide (2D-MoO$_3$) in improving the electronic behaviour of the
+material. Deduction of the beneficial role of MoO$_3$ will serve to open the
+field to new approaches with regard to the tunability of 2D semiconductors by
+their low-dimensional oxides in nano-modified heterostructures.",1706.08573v1
+2017-06-27,Towards Substrate Engineering of Graphene-Silicon Schottky Diode Photodetectors,"Graphene-Silicon Schottky diode photodetectors possess beneficial properties
+such as high responsivities and detectivities, broad spectral wavelength
+operation and high operating speeds. Various routes and architectures have been
+employed in the past to fabricate devices. Devices are commonly based on the
+removal of the silicon-oxide layer on the surface of silicon by wet-etching
+before deposition of graphene on top of silicon to form the graphene-silicon
+Schottky junction. In this work, we systematically investigate the influence of
+the interfacial oxide layer, the fabrication technique employed and the silicon
+substrate on the light detection capabilities of graphene-silicon Schottky
+diode photodetectors. The properties of devices are investigated over a broad
+wavelength range from near-UV to short-/mid-infrared radiation, radiation
+intensities covering over five orders of magnitude as well as the suitability
+of devices for high speed operation. Results show that the interfacial layer,
+depending on the required application, is in fact beneficial to enhance the
+photodetection properties of such devices. Further, we demonstrate the
+influence of the silicon substrate on the spectral response and operating
+speed. Fabricated devices operate over a broad spectral wavelength range from
+the near-UV to the short-/mid-infrared (thermal) wavelength regime, exhibit
+high photovoltage responses approaching 10$^6$ V/W and short rise- and
+fall-times of tens of nanoseconds.",1706.09042v1
+2017-06-28,Suppressed carrier density for the patterned high mobility two-dimensional electron gas at gamma-Al2O3/SrTiO3 heterointerfaces,"The two-dimensional electron gas (2DEG) at the non-isostructural interface
+between spinel gamma-Al2O3 and perovskite SrTiO3 is featured by a record
+electron mobility among complex oxide interfaces in addition to a high carrier
+density up to the order of 1E15 cm-2. Herein, we report on the patterning of
+2DEG at the gamma-Al2O3/SrTiO3 interface grown at 650 {\deg}C by pulsed laser
+deposition using a hard mask of LaMnO3. The patterned 2DEG exhibits a critical
+thickness of 2 unit cells of gamma-Al2O3 for the occurrence of interface
+conductivity, similar to the unpatterned sample. However, its maximum carrier
+density is found to be approximately 3E13 cm-2, much lower than that of the
+unpatterned sample (1E15 cm-2). Remarkably, a high electron mobility of
+approximately 3,600 cm2V-1s-1 was obtained at low temperatures for the
+patterned 2DEG at a carrier density of 7E12 cm-2, which exhibits clear
+Shubnikov-de Hass quantum oscillations. The patterned high-mobility 2DEG at the
+gamma-Al2O3/SrTiO3 interface paves the way for the design and application of
+spinel/perovskite interfaces for high-mobility all-oxide electronic devices.",1706.09235v1
+2017-06-29,"Electrical Properties and Subband Occupancy at the (La,Sr)(Al,Ta)O$_3$/SrTiO$_3$ Interface","The quasi two-dimensional electron gas (q-2DEG) at oxide interfaces provides
+a platform for investigating quantum phenomena in strongly correlated
+electronic systems. Here, we study the transport properties at the
+high-mobility
+(La$_{0.3}$Sr$_{0.7}$)(Al$_{0.65}$Ta$_{0.35}$)O$_{0.3}$/SrTiO$_{0.3}$
+(LSAT/STO) interface. Before oxygen annealing, the as-grown interface exhibits
+a high electron density and electron occupancy of two subbands: higher-mobility
+electrons ($\mu_1\approx{10^4}$ cm$^2$V$^{-1}$s$^{-1}$ at 2 K) occupy the
+lower-energy $3d_{xy}$ subband, while lower-mobility electrons
+($\mu_1\approx{10^3}$ cm$^{2}$V$^{-1}$s$^{-1}$ at 2 K) propagate in the
+higher-energy $3d_{xz/yz}$-dominated subband. After removing oxygen vacancies
+by annealing in oxygen, only a single type of 3dxy electrons remain at the
+annealed interface, showing tunable Shubnikov-de Haas (SdH) oscillations below
+9 T at 2 K and an effective mass of $0.7m_e$. By contrast, no oscillation is
+observed at the as-grown interface even when electron mobility is increased to
+$50,000$ cm$^{2}$V$^{-1}$s$^{-1}$ by gating voltage. Our results reveal the
+important roles of both carrier mobility and subband occupancy in tuning the
+quantum transport at oxide interfaces.",1706.09592v1
+2017-07-20,Superconductivity proximate to antiferromagnetism in a copper-oxide monolayer grown on Bi$_2$Sr$_2$CaCu$_2$O$_{8+δ}$,"A nodeless superconducting (SC) gap was reported in a recent scanning
+tunneling spectroscopy experiment of a copper-oxide monolayer grown on the
+Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ (Bi2212) substrate [Y. Zhong {\it et al.},
+Sci. Bull. {\bf 61}, 1239 (2016)], which is in stark contrast to the nodal
+d-wave pairing gap in the bulk cuprates. Motivated by this experiment, we first
+show with first-principles calculations that the tetragonal CuO (T-CuO)
+monolayer on the Bi2212 substrate is more stable than the commonly postulated
+CuO$_{2}$ structure. The T-CuO monolayer is composed of two CuO$_2$ layers
+sharing the same O atoms. The band structure is obtained by first-principles
+calculations, and its strong electron correlation is treated with the
+renormalized mean-field theory. We argue that one CuO$_2$ sublattice is hole
+doped while the other sublattice remains half filled and may have
+antiferromagnetic (AF) order. The doped Cu sublattice can show d-wave SC;
+however, its proximity to the AF Cu sublattice induces a spin-dependent
+hopping, which splits the Fermi surface and may lead to a full SC gap.
+Therefore, the nodeless SC gap observed in the experiment could be accounted
+for by the d-wave SC proximity to an AF order, thus it is extrinsic rather than
+intrinsic to the CuO$_2$ layers.",1707.06346v2
+2017-10-04,Effects of porosity in a model of corrosion and passive layer growth,"We introduce a stochastic lattice model to investigate the effects of pore
+formation in a passive layer grown with products of metal corrosion. It
+considers that an anionic species diffuses across that layer and reacts at the
+corrosion front (metal-oxide interface), producing a random distribution of
+compact regions and large pores, respectively represented by O (oxide) and P
+(pore) sites. O sites are assumed to have very small pores, so that the
+fraction $\Phi$ of P sites is an estimate of the porosity, and the ratio
+between anion diffusion coefficients in those regions is $D_{\text r}<1$.
+Simulation results without the large pores ($\Phi =0$) are similar to those of
+a formerly studied model of corrosion and passivation and are explained by a
+scaling approach. If $\Phi >0$ and $D_{\text r}\ll 1$, significant changes are
+observed in passive layer growth and corrosion front roughness. For small
+$\Phi$, a slowdown of the growth rate is observed, which is interpreted as a
+consequence of the confinement of anions in isolated pores for long times.
+However, the presence of large pores near the corrosion front increases the
+frequency of reactions at those regions, which leads to an increase in the
+roughness of that front. This model may be a first step to represent defects in
+a passive layer which favor pitting corrosion.",1710.01548v1
+2017-10-06,A new role for exhaled nitric oxide as a functional marker of peripheral airway caliber changes: a theoretical study,"Though considered as an inflammation marker, exhaled nitric oxide (FENO) was
+shown to be sensitive to airway caliber changes to such an extent that it might
+be considered as a marker of them. It is thus important to understand how these
+changes and their localization mechanically affect the total NO flux
+penetrating the airway lumen (JawNO), hence FENO, independently from any
+inflammatory status change. A new model was used which simulates NO production,
+consumption and diffusion inside the airway epithelium wall, then, NO excretion
+through the epithelial wall into the airway lumen and, finally, its axial
+transport by diffusion and convection in the airway lumen. This model may also
+consider the presence of a mucus layer coating the epithelial wall. Simulations
+were performed that showed the great sensitivity of JawNO to peripheral airways
+caliber changes. Moreover, FENO showed distinct behaviors depending on the
+location of the caliber change. Considering a bronchodilation, absence of FENO
+change was associated with dilation of central airways, FENO increase with
+dilation up to pre-acinar small airways, and FENO decrease with intra-acinar
+dilation due to amplification of the back-diffusion flux. The presence of a
+mucus layer was also shown to play a significant role in FENO changes.
+Altogether, the present work provides theoretical evidences that specific FENO
+changes in acute situations are linked to specifically located airway caliber
+changes in the lung periphery. This opens the way for a new role for FENO as a
+functional marker of peripheral airway caliber change.",1710.02362v1
+2017-10-16,Microscopic origin of the mobility enhancement at a spinel/perovskite oxide heterointerface revealed by photoemission spectroscopy,"The spinel/perovskite heterointerface $\gamma$-Al$_2$O$_3$/SrTiO$_3$ hosts a
+two-dimensional electron system (2DES) with electron mobilities exceeding those
+in its all-perovskite counterpart LaAlO$_3$/SrTiO$_3$ by more than an order of
+magnitude despite the abundance of oxygen vacancies which act as electron
+donors as well as scattering sites. By means of resonant soft x-ray
+photoemission spectroscopy and \textit{ab initio} calculations we reveal the
+presence of a sharply localized type of oxygen vacancies at the very interface
+due to the local breaking of the perovskite symmetry. We explain the
+extraordinarily high mobilities by reduced scattering resulting from the
+preferential formation of interfacial oxygen vacancies and spatial separation
+of the resulting 2DES in deeper SrTiO$_3$ layers. Our findings comply with
+transport studies and pave the way towards defect engineering at interfaces of
+oxides with different crystal structures.",1710.05574v1
+2017-10-23,Realization of a hole-doped Mott insulator on a triangular silicon lattice,"The physics of doped Mott insulators is at the heart of some of the most
+exotic physical phenomena in materials research including insulator-metal
+transitions, colossal magneto-resistance, and high-temperature
+superconductivity in layered perovskite compounds. Advances in this field would
+greatly benefit from the availability of new material systems with similar
+richness of physical phenomena, but with fewer chemical and structural
+complications in comparison to oxides. Using scanning tunneling microscopy and
+spectroscopy, we show that such a system can be realized on a silicon platform.
+Adsorption of one-third monolayer of Sn atoms on a Si(111) surface produces a
+triangular surface lattice with half-filled dangling bond orbitals. Modulation
+hole-doping of these dangling bonds unveils clear hallmarks of Mott physics,
+such as spectral weight transfer and the formation of quasi-particle states at
+the Fermi level, well-defined Fermi contour segments, and a sharp singularity
+in the density of states. These observations are remarkably similar to those
+made in complex oxide materials, including high-temperature superconductors,
+but highly extraordinary within the realm of conventional sp-bonded
+semiconductor materials. It suggests that exotic quantum matter phases can be
+realized and engineered on silicon-based materials platforms.",1710.08065v1
+2017-10-30,Evidence for thermal activation in the glassy dynamics of insulating granular aluminum conductance,"Insulating granular aluminum is one of the proto-typical disordered
+insulators whose low temperature electrical conductance exhibits ubiquitous
+non-equilibrium phenomena. These include slow responses to temperature or gate
+voltage changes, characteristic field effect anomalies and ageing phenomena
+typical of a glass. In this system the influence of temperature on the glassy
+dynamics has remained elusive, leading to the belief that the slow relaxations
+essentially proceed via elastic quantum tunneling. A similar situation was met
+in insulating indium oxide and it was concluded that in high carrier density
+Anderson insulators, electrons form a quantum glass phase. In this work we
+experimentally demonstrate that thermal effects do play a role and that the
+slow dynamics in granular aluminum is subject to thermal activation. We show
+how its signatures can be revealed and activation energy distributions can be
+extracted, providing a promising grasp on the nature of the microscopic
+mechanism at work in glassy Anderson insulators. We explain why some of the
+experimental protocols previously used in the literature fail to reveal thermal
+activation in these systems. Our results and analyses call for a reassessment
+of the emblematic case of indium oxide, and question the existence of a quantum
+glass in any of the systems studied so far.",1710.10939v1
+2017-10-30,Rayleigh-Brillouin light scattering spectroscopy of nitrous oxide (N$_2$O),"High signal-to-noise and high-resolution light scattering spectra are
+measured for nitrous oxide (N$_2$O) gas at an incident wavelength of 403.00 nm,
+at 90$^\circ$ scattering, at room temperature and at gas pressures in the range
+$0.5-4$ bar. The resulting Rayleigh-Brillouin light scattering spectra are
+compared to a number of models describing in an approximate manner the
+collisional dynamics and energy transfer in this gaseous medium of this
+polyatomic molecular species. The Tenti-S6 model, based on macroscopic gas
+transport coefficients, reproduces the scattering profiles in the entire
+pressure range at less than 2\% deviation at a similar level as does the
+alternative kinetic Grad's 6-moment model, which is based on the internal
+collisional relaxation as a decisive parameter. A hydrodynamic model fails to
+reproduce experimental spectra for the low pressures of 0.5-1 bar, but yields
+very good agreement ($< 1$\%) in the pressure range $2-4$ bar. While these
+three models have a different physical basis the internal molecular relaxation
+derived can for all three be described in terms of a bulk viscosity of $\eta_b
+\sim (6 \pm 2) \times 10^{-5}$ Pa$\cdot$s. A 'rough-sphere' model, previously
+shown to be effective to describe light scattering in SF$_6$ gas, is not found
+to be suitable, likely in view of the non-sphericity and asymmetry of the N-N-O
+structured linear polyatomic molecule.",1710.11193v1
+2017-10-31,Switching between normal and anomalous Laser Induced Periodic Surface Structures,"We report on the studies of switching mechanism between normal and anomalous
+laser induced periodic surface structures. We have shown that for high loss
+metals the switching mechanism between normal and anomalous modes relays on an
+interplay between two different feedbacks inherent into the structure formation
+process: long range, low intensity dipole-like scattering of light along the
+surface, which governs anomalous ripples parallel to the laser polarization,
+and short range, high intensity plasmon-polariton wave, which is initiated by
+near field dipole radiation and responsible for creation of ripples
+perpendicular to the polarization, i. e. normal structure. By managing these
+two feedbacks, we demonstrated creation of both normal and anomalous laser
+induced periodic surface structures on the same surface. In contrast to the
+previous studies, we have shown that the thermal oxidation mechanism can form
+both normal and anomalous types of the structure, while the ablation mechanism
+is involved only during the normal structure formation. Unlike the formation of
+oxidation type anomalous structure, the formation of ablation type normal
+structure does not have inherent negative feedback, which is self-regulating
+nano-ripples formation. This feedback needs to be applied artificially, by
+regulating scanning speed and pulse energy at a given repetition rate of the
+laser. With implementation of nonlinear laser lithography technique for
+ablation type of normal laser induced periodic surface structures we
+demonstrated large area high regular nano-grating formation on different
+surfaces with extremely high industrially acceptable speed.",1710.11405v1
+2017-11-28,Electrooxidation of a cobalt based steel in LiOH: a non-noble metal based electro-catalyst suitable for durable water-splitting in an acidic milieu,"The use of proton exchange membrane (PEM) electrolyzers is the method of
+choice for the conversion of solar energy when frequently occurring changes of
+the current load are an issue. However, this technique requires electrolytes
+with low pH. All oxygen evolving electrodes working durably and actively in
+acids contain IrOx. Due to their scarcity and high acquisition costs, noble
+elements like Pt, Ru and Ir need to be replaced by earth abundant elements. We
+have evaluated a cobalt containing steel for use as an oxygen-forming electrode
+in H2SO4. We found that the dissolving of ingredients out of the steel
+electrode at oxidative potential in sulfuric acid, which is a well-known,
+serious issue, can be substantially reduced when the steel is electro-oxidized
+in LiOH prior to electrocatalysis. Under optimized synthesis conditions a
+cobalt-containing tool steel was rendered into a durable oxygen evolution
+reaction (OER) electrocatalyst (weight loss: 39 mug mm-2 after 50 000 s of
+chronopotentiometry at pH 1) that exhibits overpotentials down to 574 mV at 10
+mA cm-2 current density at pH 1. Focused ion beam SEM FIB-SEM) was successfully
+used to create a structure-stability relationship.",1712.01100v1
+2017-12-05,Micro solid oxide fuel cells: a new generation of micro-power sources for portable applications,"Portable electronic devices are already an indispensable part of our daily
+life; and their increasing number and demand for higher performance is becoming
+a challenge for the research community. In particular, a major concern is the
+way to efficiently power these energy-demanding devices, assuring long grid
+independency with high efficiency, sustainability and cheap production. In this
+context, technologies beyond Li-ion are receiving increasing attention, among
+which the development of micro solid oxide fuel cells ({\mu}SOFC) stands out.
+In particular, {\mu}SOFC provides a high energy density, high efficiency and
+opens the possibility to the use of different fuels, such as hydrocarbons. Yet,
+its high operating temperature has typically hindered its application as
+miniaturized portable device. Recent advances have however set a completely new
+range of lower operating temperatures, i.e. 350-450C, as compared to the
+typical >900C needed for classical bulk SOFC systems. In this work, a
+comprehensive review of the status of the technology is presented. The main
+achievements, as well as the most important challenges still pending are
+discussed, regarding (i.) the cell design and microfabrication, and (ii.) the
+integration of functional electrolyte and electrode materials. To conclude, the
+different strategies foreseen for a wide deployment of the technology as new
+portable power source are underlined.",1712.01589v1
+2017-12-21,A Review and Outlook for the Removal of Radon-Generated Po-210 Surface Contamination,"The next generation low-background detectors operating deep underground aim
+for unprecedented low levels of radioactive backgrounds. The deposition and
+presence of radon progeny on detector surfaces is an added source of energetic
+background events. In addition to limiting the detector material's radon
+exposure in order to reduce potential surface backgrounds, it is just as
+important to clean surfaces to remove inevitable contamination. Such studies of
+radon progeny removal have generally found that a form of etching is effective
+at removing some of the progeny (Bi and Pb), however more aggressive
+techniques, including electropolishing, have been shown to effectively remove
+the Po atoms. In the absence of an aggressive etch, a significant fraction of
+the Po atoms are believed to either remain behind within the surface or
+redeposit from the etching solution back onto the surface. We explore the
+chemical nature of the aqueous Po ions and the effect of the oxidation state of
+Po to maximize the Po ions remaining in the etching solution of contaminated Cu
+surfaces. We present a review of the previous studies of surface radon progeny
+removal and our findings on the role of oxidizing agents and a cell potential
+in the preparation of a clean etching technique.",1712.08167v1
+2017-12-27,Stable Self-Assembled Atomic-Switch Networks for Neuromorphic Applications,"Nature inspired neuromorphic architectures are being explored as an
+alternative to imminent limitations of conventional complementary metal-oxide
+semiconductor (CMOS) architectures. Utilization of such architectures for
+practical applications like advanced pattern recognition tasks will require
+synaptic connections that are both reconfigurable and stable. Here, we report
+realization of stable atomic-switch networks (ASN), with inherent complex
+connectivity, self-assembled from percolating metal nanoparticles (NPs). The
+device conductance reflects the configuration of synapses which can be
+modulated via voltage stimulus. By controlling Relative Humidity (RH) and
+oxygen partial-pressure during NP deposition we obtain stochastic conductance
+switching that is stable over several months. Detailed characterization reveals
+signatures of electric-field induced atomic-wire formation within the
+tunnel-gaps of the oxidized percolating network. Finally we show that the
+synaptic structure can be reconfigured by stimulating at different repetition
+rates, which can be utilized as short-term to long-term memory conversion. This
+demonstration of stable stochastic switching in ASNs provides a promising route
+to hardware implementation of biological neuronal models and, as an example, we
+highlight possible applications in Reservoir Computing (RC).",1712.09497v1
+2018-01-02,Tuning Nanocrystal Surface Depletion by Controlling Dopant Distribution as a Route Toward Enhanced Film Conductivity,"Electron conduction through bare metal oxide nanocrystal (NC) films is
+hindered by surface depletion regions resulting from the presence of surface
+states. We control the radial dopant distribution in tin-doped indium oxide
+(ITO) NCs as a means to manipulate the NC depletion width. We find in films of
+ITO NCs of equal overall dopant concentration that those with dopant-enriched
+surfaces show decreased depletion width and increased conductivity. Variable
+temperature conductivity data shows electron localization length increases and
+associated depletion width decreases monotonically with increased density of
+dopants near the NC surface. We calculate band profiles for NCs of differing
+radial dopant distributions and, in agreement with variable temperature
+conductivity fits, find NCs with dopant-enriched surfaces have narrower
+depletion widths and longer localization lengths than those with
+dopant-enriched cores. Following amelioration of NC surface depletion by atomic
+layer deposition of alumina, all films of equal overall dopant concentration
+have similar conductivity. Variable temperature conductivity measurements on
+alumina-capped films indicate all films behave as granular metals. Herein, we
+conclude that dopant-enriched surfaces decrease the near-surface depletion
+region, which directly increases the electron localization length and
+conductivity of NC films.",1801.00731v1
+2018-01-15,Role of Water Molecule in Enhancing the Proton Conductivity on Graphene Oxide at Humidity Condition,"Recent experimental reports on in-plane proton conduction in reduced graphene
+oxide (rGO) films open a new way for the design of proton exchange membrane
+essential in fuel cells and chemical filters. At high humidity condition, water
+molecules attached on the rGO sheet are expected to play a critical role, but
+theoretical works for such phenomena have been scarcely found in the
+literature. In this study, we investigate the proton migration on
+water-adsorbed monolayer and bilayer rGO sheets using first-principles
+calculations in order to reveal the mechanism. We devise a series of models for
+the water-adsorbed rGO films as systematically varying the reduction degree and
+water content, and optimize their atomic structures in reasonable agreement
+with the experiment, using a density functional that accounts for van der Waals
+correction. Upon suggesting two different transport mechanisms, epoxy-mediated
+and water-mediated hoppings, we determine the kinetic activation barriers for
+these in-plane proton transports on the rGO sheets. Our calculations indicate
+that the water-mediated transport is more likely to occur due to its much lower
+activation energy than the epoxy-mediated one and reveal new prospects for
+developing efficient solid proton conductors.",1801.04648v2
+2018-01-24,Ultrafast orbital manipulation and Mott physics in multi-band correlated materials,"Multiorbital correlated materials are often on the verge of multiple
+electronic phases (metallic, insulating, super- conducting, charge and
+orbitally ordered), which can be explored and controlled by small changes of
+the external parameters. The use of ultrashort light pulses as a mean to
+transiently modify the band population is leading to fundamentally new results.
+In this paper we will review recent advances in the field and we will discuss
+the pos- sibility of manipulating the orbital polarization in correlated
+multi-band solid state systems. This technique can provide new understanding of
+the ground state properties of many interesting classes of quantum materials
+and offers a new tool to induce transient emergent properties with no
+counterpart at equilibrium. We will address: the discovery of high-energy
+Mottness in superconducting copper oxides and its impact on our understanding
+of the cuprate phase diagram; the instability of the Mott insulating phase in
+photoexcited vanadium oxides; the manipulation of orbital-selective
+correlations in iron-based superconductors; the pumping of local electronic
+excitons and the consequent transient effective quasiparticle cooling in
+alkali-doped fullerides. Finally, we will discuss a novel route to manipulate
+the orbital polarization in a a k-resolved fashion.",1801.07957v1
+2018-09-05,Radial and vertical dust transport inhibit refractory carbon depletion in protoplanetary disks,"The Earth is strongly depleted in carbon compared to the dust in the ISM,
+implying efficient removal of refractory carbon before parent body formation.
+It has been argued that grains get rid of their carbon through oxidation and
+photolysis in the exposed upper disk layers. We assess the efficacy of these
+C-removal mechanisms accounting for the vertical and radial transport of
+grains. We obtain the carbon and carbon free mass budget of solids by solving
+two 1D advection-diffusion equations, accounting for the dust grain size
+distribution and radial transport. The carbon removal acts on the fraction of
+the grains that are in the exposed layer and requires efficient vertical
+transport. In models without radial transport, oxidation and photolysis can
+destroy most of the refractory carbon in terrestrial planet formation region.
+But it only reaches the observed depletion levels for extreme parameter
+combinations and requires that parent body formation was delayed by 1 Myr.
+Adding radial transport of solids prevents the depletion entirely, leaving
+refractory carbon equally distributed throughout the disk. It is unlikely that
+the observed carbon depletion can ultimately be attributed to mechanisms
+operating on small grains in the disk surface layers. Other mechanisms need to
+be studied, for example flash heating events or FU Ori outbursts in order to
+remove carbon quickly and deeply. However, a sustained drift barrier or
+strongly reduced radial grain mobility are necessary to prevent replenishment
+of carbon from the outer disk.",1809.01648v1
+2018-09-06,Limits of surface analysis of thin film compounds using LEIS,"Low Energy Ion Scattering (LEIS) was employed to study the surface
+composition of thin films of Ru on B, C and B4C films at different stages of
+growth. Effects of surface segregation of C were observed. Previously unknown
+matrix effects were observed in these samples, expressed in the decrease of
+LEIS signals of Ru, B and C at low Ru concentrations. The effect disappears for
+Ru-rich surfaces. Measurements with different He+ ion energies prove that the
+characteristic velocities of the elements involved change with surface
+composition. We suggest that these matrix effects appear due to the changes in
+neutralization efficiency in quasiresonant neutralization from the valence band
+(VB-qRN). This neutralization channel is present in elemental C and B due to a
+wide valence band with energy states as low as -20 eV, which are in a
+(quasi-)resonance with the He 1s level. This mechanism was earlier reported for
+graphitic carbon. We suggest that it can be applied to a much wider range of
+materials, leading to potential matrix effects in LEIS from a variety of
+surfaces, containing B, C and potentially O and N atoms, e.g. borides,
+carbides, oxides and nitrides, as well as alloys with B and C. This hypothesis
+is supported by additional LEIS measurements on oxidized Ru which show matrix
+effect in Ru-O LEIS signals as well. We argue that it is possible to avoid the
+matrix effects from compounded surfaces within certain ranges of composition by
+a proper choice of reference samples, while for other compositions knowledge of
+characteristic velocities is required for reliable quantification.",1809.01918v1
+2018-09-19,"Effects of the number of layers on the vibrational, electronic and optical properties of alpha lead oxide","We have investigated the effects of number of layers on the structural,
+vibrational, electronic and optical properties of $\alpha$-PbO using first
+principles calculations. Our theoretical calculations have shown that four
+Raman active modes of $\alpha$-PbO tend to red-shift from bulk to monolayer due
+to decreasing of force constants and increasing of bond lengths. It has been
+shown that while bulk and multilayer $\alpha$-PbO have an indirect band gap,
+monolayer form has a direct band gap value of 2.59 eV. Although lead atoms have
+5d states, spin-orbit coupling does not significantly affect the band structure
+of $\alpha$-PbO. The computed cleavage energy value (0.67 J/m$^2$) confirms
+that monolayer PbO can be easily obtained from its bulk counterpart by
+exfoliation methods. In addition to the band structure, we also calculated the
+optical properties and absorbed photon flux $J_{abs}$ of $\alpha$-PbO
+structures to investigate the possibility of solar absorption. Our calculations
+reveal that while monolayer and bilayer PbO have relatively larger band gaps
+and lower absorption coefficients, their $J_{abs}$ values are not ideal for
+solar absorption devices. In contrast, the multilayer and bulk phases of the
+$\alpha$-PbOs show good overlap with the solar spectrum and yield high
+electrical current values. Our calculations have indicated that ultrathin films
+of $\alpha$-PbO (such as 3nm thickness) could be excellent candidates for solar
+cells. We believe that our work can be utilized to improve electronic and
+optical devices based on lead oxide structures.",1809.07263v1
+2018-09-27,Using ultra-thin parylene films as an organic gate insulator in nanowire field-effect transistors,"We report the development of nanowire field-effect transistors featuring an
+ultra-thin parylene film as a polymer gate insulator. The room temperature,
+gas-phase deposition of parylene is an attractive alternative to oxide
+insulators prepared at high temperatures using atomic layer deposition. We
+discuss our custom-built parylene deposition system, which is designed for
+reliable and controlled deposition of <100 nm thick parylene films on III-V
+nanowires standing vertically on a growth substrate or horizontally on a device
+substrate. The former case gives conformally-coated nanowires, which we used to
+produce functional $\Omega$-gate and gate-all-around structures. These give
+sub-threshold swings as low as 140 mV/dec and on/off ratios exceeding $10^3$ at
+room temperature. For the gate-all-around structure, we developed a novel
+fabrication strategy that overcomes some of the limitations with previous
+lateral wrap-gate nanowire transistors. Finally, we show that parylene can be
+deposited over chemically-treated nanowire surfaces; a feature generally not
+possible with oxides produced by atomic layer deposition due to the surface
+`self-cleaning' effect. Our results highlight the potential for parylene as an
+alternative ultra-thin insulator in nanoscale electronic devices more broadly,
+with potential applications extending into nanobioelectronics due to parylene's
+well-established biocompatible properties.",1809.10471v1
+2018-10-02,Analysis of chemical pathways for n-dodecane/air turbulent premixed flames,"This paper analyzes turbulence-chemistry interactions for an n-dodecane-air
+flame, focusing on the degree to which fuel oxidation pathways change in
+turbulent flames relative to their corresponding laminar flames. This work is
+based on a lean n-dodecane-air flame DNS database from Aspden et al. (Proc.
+Combust. Institute, 36 (2017) 2005-2016). The relative roles of dominant
+reactions that release heat and produce/consume radicals are examined at
+various turbulence intensities and compared with stretched flame calculations
+from counterflow flames and perfectly stirred reactors. These results show that
+spatially integrated (i.e. integrated heat release or radical production rate
+metrics averaged over the entire flame) chemical pathways are relatively
+insensitive to turbulence intensity and mimic the behavior of stretched flames.
+In other words, the contribution of a given reaction to heat release or radical
+production, integrated over the entire flame, is nearly independent to
+turbulence. Localized analysis conditioned on topological feature of the flame
+and on temperature is also performed. The former analysis reveals that much
+larger alteration of pathways occurs in the positively-curved regions of the
+flame. The latter localized analysis shows that peak activity in the low
+temperature (i.e. below 1200K) region shift towards higher temperatures with
+increases in Karlovitz number. This result is particularly interesting given
+that prior work with lighter fuels showed the opposite behavior suggesting a
+disparate response of the reactions involved in the fuel oxidation process to
+increased turbulence.",1810.01450v1
+2018-10-08,Metasurface reconfiguration through lithium ion intercalation in a transition metal oxide,"In the latest years the optical engineer's toolbox has welcomed a new
+concept, the metasurface. In a metasurface, properly tailored material
+inclusions are able to reshape the electromagnetic field of an incident beam.
+Change of amplitude, phase and polarization can be addressed within a thickness
+of only a fraction of a wavelength. By means of this concept, a radical gain in
+compactness of optical components is foreseen, even of the most complex ones;
+other unique features like that of analog computing have also been identified.
+With this huge potential ready to be disclosed, lack of tunability is still a
+main barrier to be broken. Metasurfaces must now be made reconfigurable, i.e.
+able to modify and memorize their state, possibly with a small amount of
+energy. In this Communication we report low-energy, self-holding metasurface
+reconfiguration through lithium intercalation in a vanadium pentoxide layer
+integrated within the photonic device. By a proper meta-atom design, operation
+on amplitude and phase of linearly polarized light has been demonstrated. In
+addition, manipulation of circularly polarized light in the form of tunable
+chirality and tunable handedness-preserving reflection has been implemented.
+These operations are accomplished using as low as 50 pJ/{\mu}m^{2}, raising
+lithium intercalation in transition metal oxides as one of the most energy
+efficient self-holding tuning mechanisms known so far for metasurfaces, with
+significant perspectives in the whole field of nanophotonics.",1810.03351v1
+2018-10-15,A low-disorder Metal-Oxide-Silicon double quantum dot,"One of the biggest challenges impeding the progress of Metal-Oxide-Silicon
+(MOS) quantum dot devices is the presence of disorder at the Si/SiO$_2$
+interface which interferes with controllably confining single and few
+electrons. In this work we have engineered a low-disorder MOS quantum
+double-dot device with critical electron densities, i.e. the lowest electron
+density required to support a conducting pathway, approaching critical electron
+densities reported in high quality Si/SiGe devices and commensurate with the
+lowest critical densities reported in any MOS device. Utilizing a nearby charge
+sensor, we show that the device can be tuned to the single-electron regime
+where charging energies of $\approx$8 meV are measured in both dots, consistent
+with the lithographic size of the dot. Probing a wide voltage range with our
+quantum dots and charge sensor, we detect three distinct electron traps,
+corresponding to a defect density consistent with the ensemble measured
+critical density. Low frequency charge noise measurements at 300 mK indicate a
+1/$f$ noise spectrum of 3.4 $\mu$eV/Hz$^{1/2}$ at 1 Hz and magnetospectroscopy
+measurements yield a valley splitting of 110$\pm$26 $\mu$eV. This work
+demonstrates that reproducible MOS spin qubits are feasible and represents a
+platform for scaling to larger qubit systems in MOS.",1810.06516v1
+2018-10-16,Graphene oxide for enhanced nonlinear optics in low and high index contrast waveguides and nanowires,"We demonstrate enhanced four-wave mixing (FWM) in doped silica waveguides
+integrated with graphene oxide (GO) layers. Owing to strong mode overlap
+between the integrated waveguides and GO films that have a high Kerr
+nonlinearity and low loss, the FWM efficiency of the hybrid integrated
+waveguides is significantly improved. We perform FWM measurements for different
+pump powers, wavelength detuning, GO coating lengths, and number of GO layers.
+Our experimental results show good agreement with theory, achieving up to
+~9.5-dB enhancement in the FWM conversion efficiency for a 1.5-cm-long
+waveguide integrated with 2 layers of GO. We show theoretically that for
+different waveguide geometries an enhancement in FWM efficiency of ~ 20 dB can
+be obtained in the doped silica waveguides, and more than 30 dB in silicon
+nanowires and slot waveguides. This demonstrates the effectiveness of
+introducing GO films into integrated photonic devices in order to enhance the
+performance of nonlinear optical processes.",1810.06756v3
+2018-10-24,Graphene oxide upregulates the homeostatic functions of primary astrocytes and modulates astrocyte-to-neuron communication,"Graphene-based materials are the focus of intense research efforts to devise
+novel theranostic strategies for targeting the central nervous system. In this
+work, we have investigated the consequences of long-term exposure of primary
+rat astrocytes to pristine graphene (GR) and graphene oxide (GO) flakes. We
+demonstrate that GR/GO interfere with a variety of intracellular processes as a
+result of their internalization through the endo-lysosomal pathway.
+Graphene-exposed astrocytes acquire a more differentiated morphological
+phenotype associated with extensive cytoskeletal rearrangements. Profound
+functional alterations are induced by GO internalization, including the
+upregulation of inward-rectifying K+ channels and of Na+-dependent glutamate
+uptake, which are linked to the astrocyte capacity to control the extracellular
+homeostasis. Interestingly, GO-pretreated astrocytes promote the functional
+maturation of co-cultured primary neurons by inducing an increase in intrinsic
+excitability and in the density of GABAergic synapses. The results indicate
+that graphene nanomaterials profoundly affect astrocyte physiology in vitro,
+with consequences for neuronal network activity. This work supports the view
+that GO-based materials could be of great interest to address pathologies of
+the central nervous system associated to astrocyte dysfunctions.",1810.10440v1
+2018-10-22,Experimental Investigation of Programmed State Stability in OxRAM Resistive Memories,"Oxide-based Random Access Memory (OxRAM), is part of the larger family of
+Resistive RAM (RRAM) memories. Generally OxRAM cells consist of a transition
+metal oxide (typically HfO2, Ta2O5, TiO2) sandwiched between two metal
+electrodes (typically TiN, TaN, W but also Pt, Ir). This thesis describes the
+experimental investigation performed on OxRAM memories during a 6-months
+internship project at imec research institute (Leuven, Belgium). From previous
+studies, HfO-based OxRAM memories showed good endurance properties (with more
+than 10e9 write cycles), low operating current (as low as 10 uA), and very fast
+switching (programming pulses of 100 ns). However, it has been observed that,
+under low programming current condition, data stability becomes challenging.
+Therefore, this programming state stability needed further investigation. This
+thesis addresses the problem of state stability, first, by presenting the
+equipment and algorithms used to study OxRAM state loss over short time
+intervals. Secondly, various experiments and tests are performed searching for
+a key parameter in order to control memory retention. Finally, this work
+demonstrates that resistance evolution over time is affected by both a
+determinist drift (logarithmically dependent on time) and a random stochastic
+fluctuation component. It also demonstrates that this behavior is intrinsic in
+the nature of the device itself and does not depend on processing issues or
+variation in the programming conditions. This experimental study proved the
+intrinsic nature of the program instability phenomena in OxRAM devices, which
+in turns leads to the ineffectiveness of verify algorithm for low current
+operation.",1810.10528v1
+2018-10-28,A mesoscopic model for the effective electrical conductivity of composite polymeric electrolytes,"The effective quasistatic conductivity of composite polymeric electrolytes is
+studied in terms of a hard-core--penetrable-layer model. Used to incorporate
+the interface phenomena (such as amorphization of the polymer matrix around
+filler particles, stiffening effect by those on the amorphous phase,
+irregularities of the filler grains' surfaces, etc.), the layers are assumed to
+be electrically inhomogeneous, consisting of a finite or infinite number of
+concentric uniform shells. The rules of dominance, imposed on the overlapping
+regions, are equivalent to the requirement that the local electric properties
+in the system be determined by the distance from the point of interest to the
+nearest particle's center. The desired conductivity is calculated using our
+original many-particle (compact-group) approach which, however, avoids an
+in-depth elaboration of polarization and correlation processes. The result is
+expressed through the electrical and geometrical parameters of the
+constituents. Contrasting it with experiment reveals that the theory adequately
+describes the effective conductivity as a function of the filler concentration
+and temperature for a number of polymeric composites based on poly(ethylene
+oxide) or oxymethylene-linked poly(ethylene oxide) and is more flexible in
+comparison with other theories.",1810.11892v2
+2019-06-01,"Caesium fallout in Tokyo on 15th March, 2011 is dominated by highly radioactive, caesium-rich microparticles","In order to understand the chemical properties and environmental impacts of
+low-solubility Cs-rich microparticles (CsMPs) derived from the FDNPP, the CsMPs
+collected from Tokyo were investigated at the atomic scale using
+high-resolution transmission electron microscopy (HRTEM) and dissolution
+experiments were performed on the air filters. Remarkably, CsMPs 0.58-2.0
+micrometer in size constituted 80%-89% of the total Cs radioactivity during the
+initial fallout events on 15th March, 2011. The CsMPs from Tokyo and Fukushima
+exhibit the same texture at the nanoscale: aggregates of Zn-Fe-oxide
+nanoparticles embedded in amorphous SiO2 glass. The Cs is associated with
+Zn-Fe-oxide nanoparticles or in the form of nanoscale inclusions of intrinsic
+Cs species,rather than dissolved in the SiO2 matrix. The Cs concentration in
+CsMPs from Tokyo (0.55-10.9 wt%) is generally less than that in particles from
+Fukushima (8.5-12.9 wt%).The radioactivity per unit mass of CsMPs from Tokyo is
+still as high as 1E11 Bq/g, which is extremely high for particles originating
+from nuclear accidents. Thus, inhalation of the low-solubility CsMPs would
+result in a high localized energy deposition by beta (0.51-12)*1E-3 Gy/h within
+the 100-micrometer-thick water layer on the CsMP surface) and may have
+longer-term effects compared with those predicted for soluble Cs-species.",1906.00212v2
+2019-06-16,First-Principles Study of Hydrogen Behaviors in $α$-Pu$_{2}$O$_{3}$,"The in-depth understanding of hydrogen permeation through plutonium-oxide
+overlayers is the prerequisite to evaluate the complex hydriding induction
+period of Pu. In this work, the incorporation, diffusion and dissolution of
+hydrogen in $\alpha$-Pu$_{2}$O$_{3}$ are investigated by the first-principles
+calculations and $\textit{ab initio}$ thermodynamic method based on DFT+U and
+DFT-D3 schemes. Our study reveals that the hydrogen incorporation is
+endothermic and the separated H atoms prefer to recombine as H$_{2}$ molecules
+rather than reacting with $\alpha$-Pu$_{2}$O$_{3}$. The H and H$_{2}$ diffusion
+are both feasible, generally, H will recombine first as H$_{2}$ and then
+migrate. Both pressure P$_{H2}$ and temperature can promote the hydrogen
+dissolution in $\alpha$-Pu$_{2}$O$_{3}$. The single H$_{2}$ molecule
+incorporation and (H+H$_{2}$) mixed dissolution will successively appear when
+increasing P$_{H2}$. Compared to PuO$_{2}$, this work indicates that Pu
+sesquioxide is hardly reduced by hydrogen, but the porous
+$\alpha$-Pu$_{2}$O$_{3}$ facilitates hydrogen transport in Pu oxide layers. We
+presents the microscopic picture of hydrogen behaviors in the defect-free
+$\alpha$-Pu$_{2}$O$_{3}$, which could shed some light on the study of the
+hydriding induction period of Pu.",1906.06712v2
+2019-06-24,Characterization of Surface and Structure of in-situ Doped Sol-Gel-Derived Silicon Carbide,"Silicon carbide (SiC), is an artificial semiconductor used for high-power
+transistors and blue LEDs, for its extraordinary properties. SiC would be
+attractive for more applications, but large-scale or large-surface area
+fabrication, with control over defects and surface is challenging. Sol-gel
+based techniques are an affordable alternative towards such requirements. This
+report describes two types of microcrystalline SiC derived after carbothermal
+reduction from sol-gel-based precursors, one with nitrogen added, the other
+aluminum. Characterization of their bulk, structure and surface shows that
+incorporation of dopants affects the formation of polytypes and surface
+chemistry. Nitrogen leads exclusively to cubic SiC, exhibiting a native oxide
+surface. Presence of aluminum instead promotes growth of hexagonal polytypes
+and induces self-passivation of the crystallites surface during growth. This is
+established by hydrogenation of silicon bonds and formation of a protecting
+aluminum carbonate species. XPS provides support for the suggested mechanism.
+This passivation is achieved in only one step, solely by aluminium in the
+precursor. Hence, it is shown that growth, doping and passivation of SiC can be
+performed as one-pot synthesis. Material without insulating oxide and a limited
+number of defects is highly valuable for applications involving
+surface-sensitive charge-transfer reactions, therefore the potential of this
+method is significant.",1906.09875v1
+2019-06-25,Graphene/Polyelectrolyte Layer-by-Layer Coatings for Electromagnetic Interference Shielding,"Electromagnetic interference (EMI) shielding coating materials with
+thicknesses in the microscale are required in many sectors, including
+communications, medical, aerospace and electronics, to isolate the
+electromagnetic radiation emitted from electronic equipment. We report a spray,
+layer-by-layer (LbL) coating approach to fabricate micron thick, highly-ordered
+and electrically-conductive coatings with exceptional EMI shielding
+effectiveness (EMI SE >4830 dB/mm), through the alternating self-assembly of
+negatively-charged reduced graphene oxide (RGO) and a positively-charged
+polyelectrolyte (PEI). The microstructure and resulting electrical properties
+of the (PEI/RGO)n LbL structures are studied as function of increasing mass of
+graphene deposited per cycle (keeping the PEI content constant), number of
+deposited layers (n), flake diameter and type of RGO. A strong effect of the
+lateral flake dimensions on the electrical properties is observed, which also
+influences the EMI SE. A maximum EMI SE of 29 dB is obtained for a 6 um thick
+(PEI/RGO)10 coating with 19 vol.% loading of reduced
+electrochemically-exfoliated graphene oxide flakes with diameters ~3um. This SE
+performance exceeds those previously reported for thicker graphene papers and
+bulk graphene/polymer composite films with higher RGO or graphene nanoplatelets
+contents, which represents an important step towards the fabrication of thin
+and light-weight high-performance EMI shielding structures.",1906.10394v1
+2019-07-01,Control of dopant crystallinity in electrochemically treated cuprate thin films,"We present a methodology based on \textit{ex-situ} (post-growth)
+electrochemistry to control the oxygen concentration in thin films of the
+superconducting oxide La$_2$CuO$_{4+y}$ grown epitaxially on substrates of
+isostructural LaSrAlO$_4$. The superconducting transition temperature, which
+depends on the oxygen concentration, can be tuned by adjusting the pH level of
+the base solution used for the electrochemical reaction. As our main finding,
+we demonstrate that the dopant oxygens can either occupy the interstitial layer
+in an orientationally disordered state or organize into a crystalline phase via
+a mechanism in which dopant oxygens are inserted into the substrate, changing
+the lattice symmetry of both the substrate and the epitaxial film. We discuss
+this mechanism, and describe the resulting methodology as a platform to be
+explored in thin films of other transition metal oxides.",1907.01079v1
+2019-07-03,Effect of Oxygen Defects Blocking Barriers on Gadolinium Doped Ceria (GDC) Electro-Chemo-Mechanical Properties,"Some oxygen defective metal oxides, such as cerium and bismuth oxides, have
+recently shown exceptional electrostrictive properties that are even superior
+to the best performing lead-based electrostrictors, e.g.
+lead-magnesium-niobates (PMN). Compared to piezoelectric ceramics,
+electromechanical mechanisms of such materials do not depend on crystalline
+symmetry, but on the concentration of oxygen vacancy in the lattice. In this
+work, we investigate for the first time the role of oxygen defect configuration
+on the electro-chemo-mechanical properties. This is achieved by tuning the
+oxygen defects blocking barrier density in polycrystalline gadolinium doped
+ceria with known oxygen vacancy concentration, Ce0.9Gd0.1O2-x,x= 0.05.
+Nanometric starting powders of ca. 12 nm are sintered in different conditions,
+including field assisted spark plasma sintering (SPS), fast firing and
+conventional method at high temperatures. These approaches allow controlling
+grain size and Gd-dopant diffusion, i.e. via thermally driven solute drag
+mechanism. By correlating the electro-chemo-mechanical properties, we show that
+oxygen vacancy distribution in the materials play a key role in ceria
+electrostriction, overcoming the expected contributions from grain size and
+dopant concentration.",1907.01906v1
+2019-07-09,Topological superconductivity from transverse optical phonons in oxide heterostructures,"A topological superconductor features at its boundaries and vortices Majorana
+fermions, which are potentially applicable for topological quantum
+computations. The scarcity of the known experimentally verified physical
+systems with topological superconductivity, time-reversal invariant ones in
+particular, is giving rise to a strong demand for identifying new candidate
+materials. In this research, we study a heterostructure consisting of a
+transition metal oxide two-dimensional electron gas (2DEG) sandwiched by
+insulators near the paraelectric (PE) / ferroelectric (FE) phase transition.
+Its relevant characteristics is the combination of the transition metal
+spin-orbit coupling and the soft odd-parity phonons arising from the
+ferroelectric fluctuation; it gives rise to the fluctuating Rashba effect,
+which can mediate the pairing interaction for time-reversal invariant
+topological superconductivity. As the PE / FE phase transition can be driven by
+applying strain on the heterostructure, this system provides a tunable
+electron-phonon coupling. Through the first-principle calculations on the (001)
+[BaOsO3][BaTiO3]4, we find such electron-phonon coupling to be strong over a
+wide range of applied tensile bi-axial strain in the monolayer BaOsO3
+sandwiched between the (001) BaTiO3, hence qualifying it as a good candidate
+material. Furthermore, the stability of topological superconductivity in this
+material is enhanced by its orbital physics that gives rise to the anisotropic
+dispersion.",1907.04304v2
+2019-07-16,Integrated polarizers based on graphene oxide in waveguides and ring resonators,"Integrated waveguide polarizers and polarization-selective micro-ring
+resonators (MRRs) incorporated with graphene oxide (GO) films are
+experimentally demonstrated. CMOS-compatible doped silica waveguides and MRRs
+with both uniformly coated and patterned GO films are fabricated based on a
+large-area, transfer-free, layer-by-layer GO coating method that yields precise
+control of the film thickness. Photolithography and lift-off processes are used
+to achieve photolithographic patterning of GO films with precise control of the
+placement and coating length. Detailed measurements are performed to
+characterize the performance of the devices versus GO film thickness and
+coating length as a function of polarization, wavelength and power. A high
+polarization dependent loss of ~53.8 dB is achieved for the waveguide coated
+with 2-mm-long patterned GO films. It is found that intrinsic film material
+loss anisotropy dominates the performance for less than 20 layers whereas
+polarization dependent mode overlap dominates for thicker layers. For the MRRs,
+the GO coating length is reduced to 50 microns, yielding a ~ 8.3-dB
+polarization extinction ratio between TE and TM resonances. These results offer
+interesting physical insights and trends of the layered GO films and
+demonstrate the effectiveness of introducing GO films into photonic integrated
+devices to realize high-performance polarization selective components.",1907.06861v1
+2019-07-17,Drag Reduction Performance of Mechanically Degraded Dilute Polyethylene Oxide Solutions,"Mechanical degradation of dilute solutions of polyethylene oxide (PEO) via
+chain scission was investigated within a turbulent pipe flow. Comparisons of
+the drag reduction performance with and without degradation were made by
+matching the onset of drag reduction conditions, which has been shown for PEO
+to be related to the mean molecular weight. The bulk flow behavior of both the
+degraded and non-degraded samples were generally consistent with trends
+observed in the literature, but a subset of conditions showed significant
+deviation in the slope increment (drag reduction performance) between the
+degraded and non-degraded samples. When they deviated, the degraded samples
+were consistently more efficient than the non-degraded samples even though they
+had the same mean molecular weight. The deviations were shown to scale with the
+normalized difference between the initial and final molecular weights. The
+current data and analysis as well as the literature suggests that the
+deviations in the polymer performance (slope increment) are related to changes
+in the molecular weight distribution. More specifically, the improved
+performance of the degraded samples relative to the non-degraded ones at the
+mean molecular weight of the degraded sample indicates an excess of longer
+polymer chains since the higher chain fractions in a degraded solution more
+effectively control the flow properties when within a certain degree of
+degradation and Reynolds number.",1907.07614v1
+2019-07-26,Moiré Engineering of Electronic Phenomena in Correlated Oxides,"Moir\'e engineering has recently emerged as a capable approach to control
+quantum phenomena in condensed matter systems. In van der Waals
+heterostructures, moir\'e patterns can be formed by lattice misorientation
+between adjacent atomic layers, creating long range electronic order. To date,
+moir\'e engineering has been executed solely in stacked van der Waals
+multilayers. Herein, we describe our discovery of electronic moir\'e patterns
+in films of a prototypical magnetoresistive oxide La0.67Sr0.33MnO3 (LSMO)
+epitaxially grown on LaAlO3 (LAO) substrates. Using scanning probe
+nano-imaging, we observe microscopic moir\'e profiles attributed to the
+coexistence and interaction of two distinct incommensurate patterns of strain
+modulation within these films. The net effect is that both electronic
+conductivity and ferromagnetism of LSMO are modulated by periodic moir\'e
+textures extending over mesoscopic scales. Our work provides an entirely new
+route with potential to achieve spatially patterned electronic textures on
+demand in strained epitaxial materials.",1907.11566v1
+2019-07-29,Does the boson peak survive in an ultrathin oxide glass?,"Bulk glasses exhibit extra vibrational modes at low energies, known as the
+boson peak. The microscopic dynamics in nanoscale alumina impact the
+performance of qubits and other superconducting devices, however the existence
+of the boson peak in these glasses has not been previously measured. Here we
+report neutron spectroscopy on Al/Al$_2$O$_{3-x}$ nanoparticles consisting of
+spherical metallic cores from 20 to 1000 nm surrounded by a 3.5 nm thick
+alumina glass. An intense low-energy peak is observed at $\omega_{BP}$ = 2.8
+$\pm$ 0.6 meV for highly oxidised particles, concurrent with an excess in the
+density of states. The intensity of the peak scales inversely with particle
+size and oxide fraction indicating a surface origin, and is red-shifted by 3
+meV with respect to the van-Hove singularity of $\gamma$-phase Al$_2$O$_{3-x}$
+nanocrystals. Molecular dynamics simulations of $\alpha$-Al$_2$O$_{3-x}$,
+$\gamma$-Al$_2$O$_{3-x}$ and a-Al$_2$O$_{3-x}$ show that the observed boson
+peak is a signature of the ultrathin glass surface, and the frequency is
+softened compared to that of the hypothetical bulk glass.",1907.12200v1
+2019-09-03,Strain engineering of oxide thin films for photocatalytic applications,"Photocatalytic materials are pivotal for the implementation of disruptive
+clean energy applications such as conversion of H$_{2}$O and CO$_{2}$ into
+fuels and chemicals driven by solar energy. However, efficient and
+cost-effective materials able to catalyze the chemical reactions of interest
+when exposed to visible light are scarce due to the stringent electronic
+conditions that they must satisfy. Chemical and nanostructuring approaches are
+capable of improving the catalytic performance of known photoactive compounds
+however the complexity of the synthesized nanomaterials and sophistication of
+the employed methods make systematic design of photocatalysts difficult. Here,
+we show by means of first-principles simulation methods that application of
+biaxial stress, $\eta$, on semiconductor oxide thin films can modify their
+optoelectronic and catalytic properties in a significant and predictable
+manner. In particular, we show that upon moderate tensile strains CeO$_{2}$ and
+TiO$_{2}$ thin films become suitable materials for photocatalytic conversion of
+H$_{2}$O into H$_{2}$ and CO$_{2}$ into CH$_{4}$ under sunlight. The band gap
+shifts induced by $\eta$ are reproduced qualitatively by a simple analytical
+model that depends only on structural and dielectric susceptibility changes.
+Thus, epitaxial strain represents a promising route for methodical screening
+and rational design of photocatalytic materials.",1909.00979v1
+2019-09-05,Surface Reconstruction Limited Conductivity in Block-Copolymer Li Battery Electrolytes,"Solid polymer electrolytes for lithium batteries promise improvements in
+safety and energy density if their conductivity can be increased.
+Nanostructured block copolymer electrolytes specifically have the potential to
+provide both good ionic conductivity and good mechanical properties. This study
+shows that the previously neglected nanoscale composition of the polymer
+electrolyte close to the electrode surface has an important effect on impedance
+measurements, despite its negligible extent compared to the bulk electrolyte.
+Using standard stainless steel blocking electrodes, the impedance of lithium
+salt-doped poly(isoprene-b-styrene-b-ethylene oxide) (ISO) exhibited a marked
+decrease upon thermal processing of the electrolyte. In contrast, covering the
+electrode surface with a low molecular weight poly(ethylene oxide) (PEO) brush
+resulted in higher and more reproducible conductivity values, which were
+insensitive to the thermal history of the device. A qualitative model of this
+effect is based on the hypothesis that ISO surface reconstruction at the
+different electrode surfaces leads to a change in the electrostatic double
+layer, affecting electrochemical impedance spectroscopy measurements. As a main
+result, PEO-brush modification of electrode surfaces is beneficial for the
+robust electrolyte performance of PEO-containing block-copolymers and may be
+crucial for their accurate characterization and use in Li-ion batteries.",1909.02327v1
+2019-09-26,Large-area implementation and critical evaluation of the material and fabrication aspects of a thin-film thermoelectric generator based on aluminum-doped zinc oxide,"A large-area thermoelectric generator (TEG) utilizing a folded thin-film
+concept is implemented and the performance evaluated for near room temperature
+applications having modest temperature gradients (< 50 K). The TEGs with the
+area of ~0.33 m^2 are shown capable of powering a wireless sensor node of
+multiple sensors suitable e.g. for monitoring environmental variables in
+buildings. The TEGs are based on a transparent, non-toxic and abundant
+thermoelectric material, i.e. aluminium-doped zinc oxide (AZO), deposited on
+flexible substrates. After folding, both the electrical current and heat flux
+are in the plane of the thermoelectric thin-film. Heat leakage in the folded
+TEG is shown to be minimal (close to that of air), enabling sufficient
+temperature gradients without efficient heat sinks, contrary to the
+conventional TEGs having the thermal flux and electrical current perpendicular
+to the plane of the thermoelectric films. The long-term stability studies
+reveal that there are no significant changes in the electrical or
+thermoelectric properties of AZO over several months, while the contact
+resistance between AZO and silver ink is an issue exhibiting a continuous
+increase over time. The performance of the TEGs and technological implications
+in relation to a state-of-the-art thermoelectric material are further assessed
+via a computational study.",1909.12042v2
+2019-10-02,Reversible Thermal Strain Control of Oxygen Vacancy Ordering in an Epitaxial La$_{0.5}$Sr$_{0.5}$CoO$_{3-δ}$ Film,"Reversible topotactic transitions between oxygen-vacancy-ordered structures
+in transition metal oxides provide a promising strategy for active manipulation
+of material properties. While transformations between various oxygen-deficient
+phases have been attained in bulk ABO$_{3-\delta}$ perovskites, substrate
+clamping restricts the formation of distinct ordering patterns in epitaxial
+films. Using in-situ scanning transmission electron microscopy (STEM), we image
+a thermally driven reversible transition in
+La$_{0.5}$Sr$_{0.5}$CoO$_{3-\delta}$ films on SrTiO$_3$ from a multidomain
+brownmillerite (BM) structure to a uniform phase wherein oxygen vacancies order
+in every third CoO$_x$ plane. Because temperature cycling is performed over a
+limited temperature range (25 {\deg}C - 385 {\deg}C), the oxygen deficiency
+parameter $\delta$ does not vary measurably. Under constant $\delta$, the
+topotactic transition proceeds via local reordering of oxygen vacancies driven
+by thermal strain. Atomic-resolution imaging reveals a two-step process whereby
+alternating vertically and horizontally oriented BM domains first scale in size
+to accommodate the strain induced by different thermal expansions of
+La$_{0.5}$Sr$_{0.5}$CoO$_{3-\delta}$ and SrTiO$_3$, before the new phase
+nucleates and quickly grows above 360 {\deg}C. Upon cooling, the film transform
+back to the mixed BM phase. As the structural transition is fully reversible
+and $\delta$ does not change upon temperature cycling, we rule out
+electron-beam irradiation during STEM as the driving mechanism. Instead, our
+findings demonstrate that thermal strain can solely drive topotactic phase
+transitions in perovskite oxide films, presenting opportunities for switchable
+ionic devices.",1910.00953v2
+2019-10-05,Electronic structure of bulk manganese oxide and nickel oxide from coupled cluster theory,"We describe the ground- and excited-state electronic structure of bulk MnO
+and NiO, two prototypical correlated electron materials, using coupled cluster
+theory with single and double excitations (CCSD). As a corollary, this work
+also reports the first implementation of unrestricted periodic ab initio
+equation-of motion CCSD. Starting from a Hartree-Fock reference, we find
+fundamental gaps of 3.46 eV and 4.83 eV for MnO and NiO respectively for the 16
+unit supercell, slightly overestimated compared to experiment, although
+finite-size scaling suggests that the gap is more severely overestimated in the
+thermodynamic limit. From the character of the correlated electronic bands we
+find both MnO and NiO to lie in the intermediate Mott/charge-transfer insulator
+regime, although NiO appears as a charge transfer insulator when only the
+fundamental gap is considered. While the lowest quasiparticle excitations are
+of metal 3d and O 2p character in most of the Brillouin zone, near the {\Gamma}
+point, the lowest conduction band quasiparticles are of s character. Our study
+supports the potential of coupled cluster theory to provide high level
+many-body insights into correlated solids.",1910.02191v2
+2019-10-07,Epitaxial Growth of Perovskite SrBiO$_3$ Film on SrTiO$_3$ by Oxide Molecular Beam Epitaxy,"Hole-doped perovskite bismuthates such as Ba$_{1-x}$K$_x$BiO$_3$ and
+Sr$_{1-x}$K$_x$BiO$_3$ are well-known bismuth-based oxide
+high-transition-temperature superconductors. Reported thin bismuthate films
+show relatively low quality, likely due to their large lattice mismatch with
+the substrate and a low sticking coefficient of Bi at high temperatures. Here,
+we report the successful epitaxial thin film growth of the parent compound
+strontium bismuthate SrBiO$_3$ on SrO-terminated SrTiO$_3$ (001) substrates by
+molecular beam epitaxy. Two different growth methods, high-temperature
+co-deposition or recrystallization cycles of low-temperature deposition plus
+high-temperature annealing, are developed to improve the epitaxial growth.
+SrBiO$_3$ has a pseudocubic lattice constant $\sim$4.25 \AA, an $\sim$8.8\%
+lattice mismatch on SrTiO$_3$ substrate, leading to a large strain in the first
+few unit cells. Films thicker than 6 unit cells prepared by both methods are
+fully relaxed to bulk lattice constant and have similar quality. Compared to
+high-temperature co-deposition, the recrystallization method can produce higher
+quality 1-6 unit cell films that are coherently or partially strained.
+Photoemission experiments reveal the bonding and antibonding states close to
+the Fermi level due to Bi and O hybridization, in good agreement with density
+functional theory calculations. This work provides general guidance to the
+synthesis of high-quality perovskite bismuthate films.",1910.02619v1
+2019-10-09,Stability of Nitrogen in Planetary Atmospheres in Contact with Liquid Water,"Molecular nitrogen is the most commonly assumed background gas that supports
+habitability on rocky planets. Despite its chemical inertness, nitrogen
+molecule is broken by lightning, hot volcanic vents, and bolide impacts, and
+can be converted into soluble nitrogen compounds and then sequestered in the
+ocean. The very stability of nitrogen, and that of nitrogen-based habitability,
+is thus called into question. Here we determine the lifetime of molecular
+nitrogen vis-a-vis aqueous sequestration, by developing a novel model that
+couples atmospheric photochemistry and oceanic chemistry. We find that HNO, the
+dominant nitrogen compounds produced in anoxic atmospheres, is converted to N2O
+in the ocean, rather than oxidized to nitrites or nitrates as previously
+assumed. This N2O is then released back into the atmosphere and quickly
+converted to N2. We also find that the deposition rate of NO is severely
+limited by the kinetics of the aqueous-phase reaction that converts NO to
+nitrites in the ocean. Putting these insights together, we conclude that the
+atmosphere must produce nitrogen species at least as oxidized as NO2 and HNO2
+to enable aqueous sequestration. The lifetime of molecular nitrogen in anoxic
+atmospheres is determined to be >1 billion years on temperate planets of both
+Sun-like and M dwarf stars. This result upholds the validity of molecular
+nitrogen as a universal background gas on rocky planets.",1910.04111v1
+2019-10-14,A Reversible Structural Phase Transition by Electrochemical Ion Injection into a Conjugated Polymer,"We find that conjugated polymers can undergo reversible structural phase
+transitions during electrochemical oxidation and ion injection. We study
+poly[2,5-bis(thiophenyl)-1,4-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)benzene]
+(PB2T-TEG), a conjugated polymer with glycolated side chains. Using grazing
+incidence wide angle X-ray scattering (GIWAXS), we show that, in contrast to
+previously known polymers, this polymer switches between two structurally
+distinct crystalline phases associated with electrochemical oxidation/reduction
+in an aqueous electrolyte. Importantly, we show that this unique phase change
+behavior has important physical consequences for ion transport. Notably, using
+moving front experiments visualized by both optical microscopy and
+super-resolution photoinduced force microscopy (PiFM), we show that a
+propagating ion front in PB2T-TEG exhibits non-Fickian transport, retaining a
+sharp step-edge profile, in stark contrast to the Fickian diffusion more
+commonly observed. This structural phase transition is reminiscent of those
+accompanying ion uptake in inorganic materials like LiFePO$_{4}$. We propose
+that engineering similar properties in future conjugated polymers may enable
+the realization of new materials with superior performance in electrochemical
+energy storage or neuromorphic memory applications.",1910.06440v1
+2019-10-18,Atomically Controlled Tunable Doping in High Performance WSe2 Devices,"Two-dimensional transitional metal dichalcogenide (TMD) field-effect
+transistors (FETs) are promising candidates for future electronic applications,
+owing to their excellent transport properties and potential for ultimate device
+scaling. However, it is widely acknowledged that substantial contact resistance
+associated with the contact-TMD interface has impeded device performance to a
+large extent. It has been discovered that O2 plasma treatment can convert WSe2
+into WO3-x and substantially improve contact resistances of p-type WSe2 devices
+by strong doping induced thinner depletion width. In this paper, we carefully
+study the temperature dependence of this conversion, demonstrating an oxidation
+process with a precise monolayer control at room temperature and multilayer
+conversion at elevated temperatures. Furthermore, the lateral oxidation of WSe2
+under the contact revealed by HR-STEM leads to potential unpinning of the metal
+Fermi level and Schottky barrier lowering, resulting in lower contact
+resistances. The p-doping effect is attributed to the high electron affinity of
+the formed WO3-x layer on top of the remaining WSe2 channel, and the doping
+level is found to be dependent on the WO3-x thickness that is controlled by the
+temperature. Comprehensive materials and electrical characterizations are
+presented, with a low contact resistance of ~528 ohm-um and record high
+on-state current of 320 uA/um at -1V bias being reported.",1910.08619v1
+2019-10-21,Overlooked transportation anisotropies in d-band correlated rare-earth perovskite nickelates,"Anisotropies in electronic transportations conventionally originate from the
+nature of low symmetries in crystal structures, and were not anticipated for
+perovskite oxides, the crystal asymmetricity of which is far below, e.g. van
+der Waals or topological crystal. Beyond conventional expectations, herein we
+demonstrate pronounced anisotropies in the inter-band coulomb repulsion
+dominated electronic transportation behaviors under low-dimensional confinement
+for the perovskite family of rare-earth nickelates (ReNiO3). From one aspect,
+imparting bi-axial interfacial strains upon various lattice planes results in
+extrinsic anisotropies in the abrupt orbital transitions of ReNiO3, and their
+metal to insulator transition behaviors that elevates the transition
+temperature beyond the existing merit. From the other aspect, the in-plane
+orbital entropy associated to the in-plane symmetry of the NiO6 octahedron
+within ReNiO3 causes intrinsic anisotropies for the gradually orbital
+transition with temperature to further improve their thermistor transportation
+properties. The present work unveils the overlooked role of the electronic
+orbital directionality within low dimensional correlated perovskites that can
+trigger anisotropic transportation behaviors, in spite of their relatively
+symmetric crystal structures. Establishing anisotropic transportations
+integrating the electron correlation and quantum confinement effects will bring
+in a new freedom for achieving further improvement in transportation properties
+of multi-functional perovskite oxides.",1910.09160v1
+2019-10-25,Interdiffusion between gadolinia doped ceria and yttria stabilized zirconia in solid oxide fuel cells: experimental investigation and kinetic modeling,"Interdiffusion between the yttria stabilized zirconia (YSZ) electrolyte and
+the gadolinia doped ceria (CGO) barrier layer is one of the major causes to the
+degradation of solid oxide fuel cells (SOFCs). We present in this work
+experimental investigations on CGO-YSZ bi-layer electrolyte sintered at 1250 C
+or 1315 C and element transport as a function of sintering temperature and
+dwelling time. In order to quantitatively simulate the experimental
+observations, the CALPHAD-type thermodynamic assessment of the CGO-YSZ system
+is performed by simplifying the system to a CeO2-ZrO2 quasi-binary system, and
+the kinetic descriptions (atomic mobilities) are constructed based on critical
+review of literature data. The CGO-YSZ interdiffusion is then modeled with the
+DICTRA software and the simulation results are compared with the experimental
+data under different sintering or long-term operating conditions. The
+corresponding ohmic resistance of the bi-layer electrolyte is predicted based
+on the simulated concentration profile. The results implies that the
+interdiffusion across the CGO-YSZ interface happens mainly during sintering at
+high temperature, while during long-term operation at relatively lower
+temperature the impact of interdiffusion on cell degradation is negligible.",1910.11947v2
+2019-10-31,Early stages of GaAs nanowires VLS self-catalyzed growth on silica-terminated silicon substrate: A photoemission study,"In this paper the early stages of the self-catalyzed Vapor-Liquid-Solid (VLS)
+growth of GaAs nanowires on epi-ready Si substrates by Molecular Beam Epitaxy
+(MBE) are studied. The interaction of Ga nano-droplets (NDs) with the silica
+overlayer is investigated by X-ray Photoemission Spectroscopy (XPS) and Atomic
+Force Microscopy (AFM). We show how Ga NDs drill the silica overlayer and make
+contact with bulk Si to allow GaAs nanowires (NWs) epitaxial growth by studying
+each of the three steps of the NW growth process sequentially: Ga NDs
+pre-deposition, post-deposition annealing to reach the NW growth temperature,
+and finally NW growth itself. The pre-deposition temperature allows to control
+the density and morphology of the NDs. A high enough annealing temperature
+enhances the reduction of SiOx by Ga oxidation and leads to the formation of
+holes which is seen by a new component in XPS spectra, assumed to be the
+consequence of the Ga-Si interaction. Finally, these nano-holes act as
+nucleation sites for the epitaxial GaAs VLS growth. During the GaAs growth,
+three different chemical environments of Ga are identified in Ga2p core level:
+metallic Ga due to the droplets at the top of the NWs, Ga oxide in contact with
+the SiOx overlayer and Ga arsenide from NWs.",1910.14570v1
+2020-01-14,Magnesium Oxide at Extreme Temperatures and Pressures Studied with First-Principles Simulations,"We combine two first-principles computer simulation techniques, path integral
+Monte-Carlo and density functional theory molecular dynamics, to determine the
+equation of state of magnesium oxide in the regime of warm dense matter, with
+densities ranging from 0.35 to 71~g$\,$cm$^{-3}$ and temperatures from 10,000 K
+to $5\times10^8$~K. These conditions are relevant for the interiors of giant
+planets and stars as well as for shock wave compression measurements and
+inertial confinement fusion experiments. We study the electronic structure of
+MgO and the ionization mechanisms as a function of density and temperature. We
+show that the L-shell orbitals of magnesium and oxygen hybridize at high
+density. This results into a gradual ionization of the L-shell with increasing
+density and temperature. In this regard, MgO behaves differently from pure
+oxygen, which is reflected in the shape of the MgO principal shock Hugoniot
+curve. The curve of oxygen shows two compression maxima, while that of MgO
+shows only one. We predict a maximum compression ratio of 4.66 to occur for a
+temperature of 6.73 $\times 10^7$ K. Finally we study how multiple shocks and
+ramp waves can be used to cover a large range of densities and temperatures.",2001.05300v1
+2020-01-21,Theoretical Investigation of Optical Intersubband Transitions and Infrared Photodetection in $β$-(AlxGa1-x)2O3/Ga2O3 Quantum Well Structures,"We provide theoretical consideration of intersubband transitions designed in
+the ultrawide bandgap Aluminum Gallium Oxide ((AlxGa1-x)2O3)/Gallium Oxide
+(Ga2O3)) quantum well system. Conventional material systems have matured into
+successful intersubband device applications such as large area quantum well
+infrared photodetector(QWIP) focal plane arrays for reproducible imaging
+systems but are fundamentally limited via maximum conduction band offsets to
+mid and long wavelength infrared applications. Short and near infrared devices
+are technologically important to optical communications systems and biomedical
+imaging applications, but are difficult to realize in intersubband designs for
+this reason. In this work, we use a first principles approach to estimate the
+expansive design space of monoclinic ${\beta}$(AlxGa1x)2O3/Ga2O3 material
+system, which reaches from short wavelength infrared (1 to 3{\mu}m) to far
+infrared (greater than 30{\mu}m) transition wavelengths. We estimate the
+performance metrics of two QWIPs operating in the long and short wavelength
+regimes, including an estimation of high room temperature detectivity (about
+10^11 Jones) at the optical communication wavelength {\lambda}p 1.55{\mu}m. Our
+findings demonstrate the potential of the rapidly maturing (AlxGa1-x)2O3/Ga2O3
+material system to open the door for intersubband device applications.",2001.07299v2
+2020-02-18,Proton Transport Entropy Increase In Amorphous SiO$_2$,"This paper presents a classical thermodynamic calculation of a Greens
+function that describes the declining rate of entropy growth as protons move
+under an applied electric field, through an amorphous SiO$_2$ layer in a MOS
+field-effect device gate oxide. The analysis builds on work by McLean and
+Ausman (1977) and Brown and Saks (1991). Polynomial models of fitting
+parameters dB/d$\alpha$, y$_0$, and A/y$_0$ based on interpolation TABLE I of
+McLean and Ausman are presented. Infinite boundary conditions are introduced
+for the parameter dB/d$\alpha$. Polynomial representations are shown of
+dB/d$\alpha$, y$_0$, A/y$_0$ and the Greens function as a function of the
+dispersion parameter $\alpha$. The paper shows that parameters y$_0$ and
+A/y$_0$ are nearly conic sections with small residuals of a few percent. This
+work is intended as a first step toward a near-equilibrium thermodynamic
+continuous-time random walk (CTRW) model (anomalous diffusion) of damage
+introduced into thick-oxide silicon-based powerMOS parts by space radiation
+effects such as those found in the Jovian radiation belts. Charge transport in
+amorphous silica electrical insulators is by thermally activated tunneling, not
+Brownian motion.",2002.07547v2
+2020-03-31,Design and Simulation of Memristor-Based Artificial Neural Network for Bidirectional Adaptive Neural Interface,"This article proposes a general approach to the simulation and design of a
+multilayer perceptron (MLP) network on the basis of cross-bar arrays of
+metal-oxide memristive devices. The proposed approach uses the ANNM theory,
+tolerance theory, simulation methodology and experiment design. The tolerances
+analysis and synthesis process is performed for the ANNM hardware
+implementation on the basis of two arrays of memristive microdevices in the
+original 16x16 cross-bar topology being a component of bidirectional adaptive
+neural interface for automatic registration and stimulation of bioelectrical
+activity of a living neuronal culture used in robotics control system. The ANNM
+is trained for solving a nonlinear classification problem of stable information
+characteristics registered in the culture grown on a multi-electrode array.
+Memristive devices are fabricated on the basis of a newly engineered
+Au/Ta/ZrO2(Y)/Ta2O5/TiN/Ti multilayer structure, which contains self-organized
+interface oxide layers, nanocrystals and is specially developed to obtain
+robust resistive switching with low variation of parameters. An array of
+memristive devices is mounted into a standard metal-ceramic package and can be
+easily integrated into the neurointerface circuit. Memristive devices
+demonstrate bipolar switching of anionic type between the high-resistance state
+and low-resistance state and can be programmed to set the intermediate
+resistive states with a desired accuracy. The ANNM tuning, testing and control
+are implemented by the FPGA-based control subsystem. All developed models and
+algorithms are implemented as Python-based software.",2004.00154v1
+2020-04-01,Phase transitions and spin-state of iron in FeO at the conditions of Earth's deep interior,"Iron-bearing oxides undergo a series of pressure-induced electronic, spin and
+structural transitions that can cause seismic anomalies and dynamic
+instabilities in Earth's mantle and outer core. We employ x-ray diffraction and
+x-ray emission spectroscopy along with state-of-the-art density functional plus
+dynamical mean-field theory (DFT+DMFT) to characterize the electronic structure
+and spin states, and crystal-structural properties of w\""ustite (Fe$_{1-x}$O)
+-- a basic oxide component of Earth's interior -- at high pressure-temperature
+conditions up to 140 GPa and 2100 K. We find that FeO exhibits complex
+polymorphism under pressure, with abnormal compression behavior associated with
+electron-spin and crystallographic phase transitions, and resulting in a
+substantial change of bulk modulus. Our results reveal the existence of a
+high-pressure phase characterized by a metallic high-spin state of iron at
+about the pressure-temperature conditions of Earth's core-mantle boundary. The
+presence of high-spin metallic iron near the base of the mantle can
+significantly influence the geophysical and geochemical properties of Earth's
+deep interior.",2004.00652v2
+2020-04-03,Differential coloration efficiency of electrochromic amorphous tungsten oxide as a function of intercalation level: Comparison between theory and experiment,"Optical absorption in amorphous tungsten oxide ($\textit{a}\mathrm{WO}_{3}$),
+for photon energies below that of the band gap, can be rationalized in terms of
+electronic transitions between localized states. For the study of this
+phenomenon, we employed the differential coloration efficiency concept, defined
+as the derivative of the optical density with respect to the inserted charge.
+We also made use of its extension to a complex quantity in the context of
+frequency-resolved studies. Combined $\textit{in situ}$ electrochemical and
+optical experiments were performed on electrochromic
+$\textit{a}\mathrm{WO}_{3}$ thin films for a wide lithium intercalation range
+using an optical wavelength of $810~\mathrm{nm}$ ($1.53~\mathrm{eV}$).
+Quasi-equilibrium measurements were made by chronopotentiometry (CP). Dynamic
+frequency-dependent measurements were carried out by simultaneous
+electrochemical and color impedance spectroscopy (SECIS). The differential
+coloration efficiency obtained from CP changes sign at a critical intercalation
+level. Its response exhibits an excellent agreement with a theoretical model
+that considers electronic transitions between $\mathrm{W}^{4+}$,
+$\mathrm{W}^{5+}$, and $\mathrm{W}^{6+}$ sites. For the SECIS experiment, the
+low-frequency limit of the differential coloration efficiency shows a general
+trend similar to that from CP. However, it does not change sign at a critical
+ion insertion level. This discrepancy could be due to degradation effects
+occurring in the films at high $\mathrm{Li}^+$ insertion levels. The
+methodology and results presented in this work can be of great interest both
+for the study of optical absorption in disordered materials and for
+applications in electrochromism.",2004.01516v1
+2020-04-06,Electron-polaron dichotomy of charge carriers in perovskite oxides,"Many transition metal oxides (TMOs) are Mott insulators due to strong Coulomb
+repulsion between electrons, and exhibit metal-insulator transitions (MITs)
+whose mechanisms are not always fully understood. Unlike most TMOs, minute
+doping in CaMnO3 induces a metallic state without any structural
+transformations. This material is thus an ideal platform to explore band
+formation through the MIT. Here, we use angle-resolved photoemission
+spectroscopy to visualize how electrons delocalize and couple to phonons in
+CaMnO3. We show the development of a Fermi surface where mobile electrons
+coexist with heavier carriers, strongly coupled polarons. The latter originate
+from a boost of the electron-phonon interaction (EPI). This finding brings to
+light the role that the EPI can play in MITs even caused by purely electronic
+mechanisms. Our discovery of the EPI-induced dichotomy of the charge carriers
+explains the transport response of Ce-doped CaMnO3 and suggests strategies to
+engineer quantum matter from TMOs.",2004.02953v2
+2020-04-11,Boron phosphide as a \emph{p}-type transparent conductor: optical absorption and transport through electron-phonon coupling,"Boron phosphide has recently been identified as a potential high hole
+mobility transparent conducting material. This promise arises from its low hole
+effective masses. However, BP has a relatively small 2 eV indirect band gap
+which will affect its transparency. In this work, we computationally study both
+optical absorption across the indirect gap and phonon-limited electronic
+transport to quantify the potential of boron phosphide as a \emph{p}-type
+transparent conductor. We find that phonon-mediated indirect optical absorption
+is weak in the visible spectrum and that the phonon-limited hole mobility is
+very high (around 900 cm$^2$/Vs) at room temperature. This exceptional mobility
+comes from a combination of low hole effective mass and very weak scattering by
+polar phonon modes. We rationalize the weak scattering by the less ionic
+bonding in boron phosphide compared to oxides. We suggest this could be a
+general advantage of non-oxides for \emph{p}-type transparent conducting
+applications. Using our computed properties, we assess the transparent
+conductor figure of merit of boron phosphide and shows that it exceeds by one
+order of magnitude that of established \emph{p}-type transparent conductors,
+confirming the potential of this material.",2004.05390v1
+2020-04-12,Fabrication process and failure analysis for robust quantum dots in silicon,"We present an improved fabrication process for overlapping aluminum gate
+quantum dot devices on Si/SiGe heterostructures that incorporates
+low-temperature inter-gate oxidation, thermal annealing of gate oxide, on-chip
+electrostatic discharge (ESD) protection, and an optimized interconnect process
+for thermal budget considerations. This process reduces gate-to-gate leakage,
+damage from ESD, dewetting of aluminum, and formation of undesired alloys in
+device interconnects. Additionally, cross-sectional scanning transmission
+electron microscopy (STEM) images elucidate gate electrode morphology in the
+active region as device geometry is varied. We show that overlapping aluminum
+gate layers homogeneously conform to the topology beneath them, independent of
+gate geometry, and identify critical dimensions in the gate geometry where
+pattern transfer becomes non-ideal, causing device failure.",2004.05683v3
+2020-04-14,"Forming a highly active, homogeneously alloyed AuPt co-catalyst decoration on O2 nanotubes directly during anodic growth","Au and Pt do not form homogeneous bulk alloys as they are thermodynamically
+not miscible. However, we show that anodic TiO$_2$ nanotubes (NTs) can in-situ
+be uniformly decorated with homogeneous AuPt alloy nanoparticles (NPs) during
+their anodic growth. For this, a metallic Ti substrate containing low amounts
+of dissolved Au (0.1 at%) and Pt (0.1 at%) is used for anodizing. The matrix
+metal (Ti) is converted to oxide while at the oxide/metal interface direct
+noble metal particle formation and alloying of Au and Pt takes place;
+continuously these particles are then picked up by the growing nanotube wall.
+In our experiments the AuPt alloy NPs have an average size of 4.2 nm and, at
+the end of the anodic process, are regularly dispersed over the TiO$_2$
+nanotubes. These alloyed AuPt particles act as excellent co-catalyst in
+photocatalytic H2 generation - with a H2 production of 12.04 {\mu}L h-1 under
+solar light. This represents a strongly enhanced activity as compared with
+TiO$_2$ NTs decorated with monometallic particles of Au (7 {\mu}L h-1) or Pt
+(9.96 {\mu}L h-1).",2004.06566v1
+2020-04-15,Penetration depth and gap structure in the antiperovskite oxide superconductor Sr$_{3-x}$SnO revealed by $μ$SR,"We report a $\mu$SR study on the antiperovskite oxide superconductor
+Sr$_{3-x}$SnO. With transverse-field $\mu$SR, we observed the increase of the
+muon relaxation rate upon cooling below the superconducting transition
+temperature $T_{\mathrm{c}}=5.4$ K, evidencing bulk superconductivity. The
+exponential temperature dependence of the relaxation rate $\sigma$ at low
+temperatures suggests a fully gapped superconducting state. We evaluated the
+zero-temperature penetration depth $\lambda(0)\propto1/\sqrt{\sigma(0)}$ to be
+around 320-1020 nm. Such a large value is consistent with the picture of a
+doped Dirac semimetal. Moreover, we revealed that the ratio
+$T_{\mathrm{c}}/\lambda(0)^{-2}$ is larger than those of ordinary
+superconductors and is comparable to those of unconventional superconductors.
+The relatively high $T_{\mathrm{c}}$ for small carrier density may hint at an
+unconventional pairing mechanism beyond the ordinary phonon-mediated pairing.
+In addition, zero-field $\mu$SR did not provide evidence of broken
+time-reversal symmetry in the superconducting state. These features are
+consistent with the theoretically proposed topological superconducting state in
+Sr$_{3-x}$SnO, as well as with $s$-wave superconductivity.",2004.06993v1
+2020-04-21,Solution-processed GaSe nanoflake-based films for photoelectrochemical water splitting and photoelectrochemical-type photodetectors,"Gallium selenide (GaSe) is a layered compound, which has been exploited in
+nonlinear optical applications and photodetectors due to its anisotropic
+structure and pseudo-direct optical gap. Theoretical studies predicted that its
+two-dimensional (2D) form is a potential photocatalyst for water splitting
+reactions. Herein, we first report the photoelectrochemical (PEC)
+characterization of GaSe nanoflakes (single-/few-layer flakes), produced via
+liquid phase exfoliation, for hydrogen evolution reaction (HER) and oxygen
+evolution reaction (OER) in both acidic and alkaline media. In 0.5 M H2SO4, the
+GaSe photoelectrodes display the best PEC performance, i.e. a ratiometric
+power-saved metric for HER ({\Phi}saved,HER) of 0.09% and a ratiometric
+power-saved metric for OER ({\Phi}saved,OER) of 0.25%. When used as PEC-type
+photodetectors, GaSe photoelectrodes show a responsivity of ~0.16 A W-1 upon
+455 nm illumination at light intensity of 63.5 uW cm-2 and applied potential of
+-0.3 V vs. reversible hydrogen electrode (RHE). The stability analysis of the
+GaSe photodetectors evidences a durable operation over tens of cathodic linear
+sweep voltammetry scans in 0.5 M H2SO4 for HER. Viceversa, degradation effects
+have been observed in both alkaline and anodic operation due to highly
+oxidizing environment and O2-induced (photo-)oxidation effects. Our results
+provide new insight into PEC properties of GaSe nanoflakes for their
+exploitation in photoelectrocatalysis, PEC-type photodetectors and
+(bio)sensors.",2004.10034v1
+2020-04-23,Topological Hall effect in single thick SrRuO3 layers induced by defect engineering,"The topological Hall effect (THE) has been discovered in ultrathin SrRuO3
+(SRO) films, where the interface between the SRO layer and another oxide layer
+breaks the inversion symmetry resulting in the appearance of THE. Thus, THE
+only occurs in ultra-thin SRO films of several unit cells. In addition to
+employing a heterostructure, the inversion symmetry can be broken intrinsically
+in bulk SRO by introducing defects. In this study THE is observed in 60 nm
+thick SRO films, in which defects and lattice distortions are introduced by
+helium ion irradiation. The irradiated SRO films exhibit a pronounced THE in a
+wide temperature range from 5 K to 80 K. These observations can be attributed
+to the emergence of Dzyaloshinskii-Moriya interaction as a result of artificial
+inversion symmetry breaking associated to the lattice defect engineering. The
+creation and control of the THE in oxide single layers can be realized by ex
+situ film processing. Therefore, this work provides new insights into the THE
+and illustrates a promising strategy to design novel spintronics devices.",2004.11301v1
+2020-04-24,Robust and Bright Photoluminescence from Colloidal Nanocrystal / Al$_2$O$_3$ Composite Films fabricated by Atomic Layer Deposition,"Colloidal nanocrystals are a promising fluorescent class of materials, whose
+spontaneous emission features can be tuned over a broad spectral range via
+their composition, geometry and size. However, towards embedding nanocrystals
+films in elaborated device geometries, one significant drawback is the
+sensitivity of their emission properties on further fabrication processes like
+lithography, metal or oxide deposition, etc. In this work, we demonstrate how
+bright emitting and robust thin films can be obtained by combining nanocrystal
+deposition from solutions via spin2 coating with subsequent atomic layer
+deposition of alumina. For the resulting composite films, the layer thickness
+can be controlled on the nanoscale, and their refractive index can be finely
+tuned by the amount of deposited alumina. Ellipsometry is used to measure the
+real and imaginary part of the dielectric permittivity, which gives direct
+access to the wavelength dependent refractive index absorbance of the film.
+Detailed analysis of the photophysics of thin films of core-shell nanocrystal
+with different shape and different shell thickness allow to correlate the
+behavior of the photoluminescence and of the decay life time to the changes in
+the non-radiative rate that are induced by the alumina deposition. We show that
+the photoemission properties of such composite films are stable in wavelength
+and intensity over several months, and that the photoluminescence completely
+recovers from heating processes up to 240$^\circ$C. The latter is particularly
+interesting, since it demonstrates robustness to the typical heat treatment
+that is needed in several process steps like resist-based lithography and
+deposition by thermal or electron beam evaporation of metals or oxides.",2004.11634v1
+2020-04-14,Photoanodes Based on TiO$_2$ and $α$-Fe$_2$O$_3$ for Solar Water Splitting Superior Role of 1D Nanoarchitectures and of Combined Heterostructures,"Solar driven photoelectrochemical water splitting (PEC-WS) using
+semiconductor photoelectrodes represents a promising approach for a sustainable
+and environmentally friendly production of renewable energy vectors and fuel
+sources, such as dihydrogen (H2). In this context, titanium dioxide (TiO$_2$)
+and iron oxide (hematite, $\alpha$-Fe$_2$O$_3$) are among the most investigated
+candidates as photoanode materials, mainly owing to their resistance to
+photocorrosion, non-toxicity, natural abundance, and low production cost. Major
+drawbacks are, however, an inherently low electrical conductivity and a limited
+hole diffusion length that significantly affect the performance of TiO$_2$ and
+$\alpha$-Fe$_2$O$_3$ in PEC devices. To this regard, one-dimensional (1D)
+nanostructuring is typically applied as it provides several superior features
+such as a significant enlargement of the material surface area, extended
+contact between the semiconductor and the electrolyte and, most remarkably,
+preferential electrical transport that overall suppress charge carrier
+recombination and improve TiO$_2$ and $\alpha$-Fe$_2$O$_3$
+photo-electrocatalytic properties. The present review describes various
+synthetic methods, properties and PEC applications of 1D-photoanodes
+(nanotubes, nanorods, nanofibers, nanowires) based on titania, hematite, and on
+$\alpha$-Fe$_2$O$_3$/TiO$_2$ heterostructures. Various routes towards
+modification and enhancement of PEC activity of 1D photoanodes are also
+discussed including doping, decoration with co-catalysts and heterojunction
+engineering. Finally, the challenges related to the optimization of charge
+transfer kinetics in both oxides are highlighted.",2004.12844v1
+2020-04-27,Exploring Nanoscale Ferroelectricity in Doped Hafnium Oxide by Interferometric Piezoresponse Force Microscopy,"Hafnium oxide (HfO2)-based ferroelectrics offer remarkable promise for memory
+and logic devices in view of their compatibility with traditional silicon CMOS
+technology, high switchable polarization, good endurance and thickness
+scalability. These factors have led to steep rise in research on this class of
+materials over the past number of years. At the same time, only a few reports
+on the direct sensing of nanoscale ferroelectric properties exist, with many
+questions remaining regarding the emergence of ferroelectricity in these
+materials. While piezoresponse force microscopy (PFM) is ideally suited to
+probe piezo- and ferro-electricity on the nanoscale, it is known to suffer
+artifacts which complicate quantitative interpretation of results and can even
+lead to claims of ferroelectricity in materials which are not ferroelectric. In
+this paper we explore the possibility of using an improved PFM method based on
+interferometric displacement sensing (IDS) to study nanoscale ferroelectricity
+in bare Si doped HfO2. Our results indicate a clear difference in the local
+remnant state of various HfO2 crystallites with reported values for the
+piezoelectric coupling in range 0.6-1.5 pm/V. In addition, we report unusual
+ferroelectric polarization switching including possible contributions from
+electrostriction and Vegard effect, which may indicate oxygen vacancies or
+interfacial effects influence the emergence of nanoscale ferroelectricity in
+HfO2.",2004.12903v2
+2020-04-28,The Prominent Charge-Transfer Effects of Trinuclear Complexes with Nominally High Nickel Valences,"Recently synthesized Rh-Ni trinuclear complexes hexacoordinated with sulfur
+ions, 3-aminopropanethiolate (apt) metalloligand
+[Ni{Rh(apt)$_{3}$}$_{2}$](NO$_{3}$)$_{n}$ ($n$ = 2, 3, 4), are found to be
+chemically interconvertible between the nominal Ni$^{2+}$ and Ni$^{4+}$ states.
+In order to clarify the origins of their interconvertible nature and the
+stability of such a high oxidation state as the tetravalency from the physical
+point of view, we have systematically investigated the local 3$d$ electronic
+structures of [Ni{Rh(apt)$_{3}$}$_{2}$](NO$_{3}$)$_{n}$ by means of soft X-ray
+core-level absorption spectroscopy (XAS). The experimental data have been
+reproduced by the single-site configuration-interaction cluster-model
+simulations, which indicate that the charge-transferred configurations are more
+stable than the nominal $d$-electron-number configuration for $n=3,4$ leading
+to the prominent charge-transfer effects. These are also supported by S
+$K$-edge XAS of [Ni{Rh(apt)$_{3}$}$_{2}$](NO$_{3}$)$_{n}$. Our results imply
+that the found charge-transfer effects have a key role to realize the
+interconvertible nature as well as the stability of the high oxidization state
+of the Ni ions.",2004.13686v1
+2020-12-06,Economically viable CO2 electroreduction embedded within ethylene oxide manufacturing,"Electrochemical conversion of CO2 (CO2R) into fuels and chemicals can both
+reduce CO2 emissions and allow for clean manufacturing in the scenario of
+significant expansion of renewable power generation. However, large-scale
+process deployment is currently limited by unfavourable process economics
+resulting from significant up- and down-stream costs for obtaining pure CO2,
+separation of reaction products and increased logistical effort. We have
+discovered a method for economically viable recycling of waste CO2 that
+addresses these challenges. Our approach is based on integration of a CO2R unit
+into an existing manufacturing process: ethylene oxide (EO) production, which
+emits CO2 as a by-product. The standard EO process separates waste CO2 from gas
+stream, hence the substrate for electroreduction is available at an EO plant at
+no additional cost. CO2 can be converted into an ethylene-rich stream and
+recycled on-site back to the EO reactor, which uses ethylene as a raw material,
+and also the anode product (oxygen) can be simultaneously valorized for the EO
+production reaction. If powered by a renewable electricity source, the process
+will significantly (ca. 80%) reduce the CO2 emissions of an EO manufacturing
+plant. A sensitivity analysis shows that the recycling approach can be
+economically viable in the short term and that its payback time could be as low
+as 1-2 years in the regions with higher carbon taxes and/or with access to
+low-cost electricity sources.",2012.03198v1
+2020-12-11,"Polyvinyl Alcohol-Few Layer Graphene Composite Films Prepared from Aqueous Colloids. Investigations of Mechanical, Conductive and Gas Barrier Properties","Quasi all water soluble composites use graphene oxide (GO) or reduced
+graphene oxide (rGO) as graphene based additives despite the long and harsh
+conditions required for their preparation. Herein, polyvinyl alcohol (PVA)
+films containing few layer graphene (FLG) are prepared by the co-mixing of
+aqueous colloids and casting, where the FLG colloid is first obtained via an
+effcient, rapid, simple, and bio-compatible exfoliation method providing access
+to relatively large FLG flakes. The enhanced mechanical, electrical
+conductivity, and O2 barrier properties of the films are investigated and
+discussed together with the structure of the films. In four different series of
+the composites, the best Young modulus is measured for the films containing
+around 1% of FLG. The most significant enhancement is obtained for the series
+with the largest FLG sheets contrary to the elongation at break which is well
+improved for the series with the lowest FLG sheets. Relatively high one-side
+electrical conductivity and low percolation threshold are achieved when
+compared to GO(rGO) composites (almost 10-3 S.cm-1 for 3% of FLG and transport
+at 0.5% FLG), while the conductivity is affected by the formation of a
+macroscopic branched FLG network. The composites demonstrate a reduction of O2
+transmission rate up to 60%.",2012.06239v1
+2020-12-19,Parallelising Electrocatalytic Nitrogen Fixation Beyond Heterointerfacial Boundary,"The nitrogen (N2) reduction reaction (NRR) is an eco-friendly alternative to
+the Haber-Bosch process to produce ammonia (NH3) with high sustainability.
+However, the significant magnitude of uphill energies in the multi-step NRR
+pathways is a bottleneck of its serial reactions. Herein, the concept of a
+parallelized reaction is proposed to actively promote NH3 production via the
+NRR using a multi-phase vanadium oxide-nitride (V2O3/VN) hybrid system. Density
+functional theory calculations revealed that the V2O3/VN junction parallelizes
+NRR pathways by exchanging intermediate N2H4* and NH2* products to avoid
+massive uphill energies towards final NH3 generation. Such an exchange is
+driven by the difference in coverage of the two species. The impact of the
+reaction parallelization strategy for multi-step nitrogen reduction is
+demonstrated with the V2O3/VN junction by an increased ammonia yield rate of
+18.36 micro mol h^-1 cm^-2 and a Faraday efficiency (FE) of 26.62% at -0.3 V
+versus a reversible hydrogen electrode in a 0.1 M aqueous KOH electrolyte, of
+which FE value exhibits 16.95 times and 6.22 times higher than that of
+single-phase V2O3 and VN, respectively. The introduction of multi-phase
+oxides/nitrides into a transition metal-based electrocatalyst can thus be a
+promising approach to realizing an alternative method for N2 fixation.",2012.10625v2
+2020-12-21,Ionic-strength and pH dependent reactivities of ascorbic acid toward ozone in aqueous micro-droplets studied by aerosol optical tweezers,"The heterogeneous oxidation reaction of single aqueous ascorbic acid (AH$_2$)
+aerosol particles with gas-phase ozone was investigated in this study utilizing
+aerosol optical tweezers with Raman spectroscopy. The measured liquid-phase
+bimolecular rate coefficients of the AH$_2$ + O$_3$ reaction exhibit a
+significant pH dependence, and the corresponding values at ionic strength 0.2 M
+are $(3.1 \pm 2.0) \times 10^5$ M$^{-1}$s$^{-1}$ and $(1.2 \pm 0.6) \times
+10^7$ M$^{-1}$s$^{-1}$ for pH $\approx$ 2 and 6, respectively. These results
+measured in micron-sized droplets agree with those from previous bulk
+measurements, indicating that the observed aerosol reaction kinetics can be
+solely explained by liquid phase diffusion and AH$_2$ + O$_3$ reaction.
+Furthermore, the results indicate that high ionic strengths could enhance the
+liquid-phase rate coefficients of the AH$_2$ + O$_3$ reaction. The results also
+exhibit a negative ozone pressure dependence that can be rationalized in terms
+of a Langmuir-Hinshelwood type mechanism for the heterogeneous oxidation of
+AH$_2$ aerosol particles by gas-phase ozone. The results of the present work
+imply that in acidified airway-lining fluids the antioxidant ability of AH$_2$
+against atmospheric ozone will be significantly suppressed.",2012.11112v2
+2020-12-22,Degradation of Nonylphenol Ethoxylate-10 (NPE-10) by Mediated Electrochemical Oxidation (MEO) Technology,"Nonylphenol ethoxylate (NPE 10) is a non ionic surfactant which is
+synthesized from alkylphenol ethoxylate. The accumulation of NPE-10 in
+wastewater will endanger the ecosystem as well as human being. At present, by
+an advancement of technology NPE 10 can be degraded indirectly by using an
+electrochemically treatment. Thus, this study aimed to evaluate the potential
+electrodegradation of NPE 10 by mediated electrochemical oxidation (MEO) using
+Ce(IV) ionic mediator. In addition, the influence of Ag(I) ionic catalyst in
+the performance of MEO for degradation of NPE 10 was also observed. The potency
+of MEO technology in degradation NPE 10 was evaluated by voltammetry technique
+and confirmed by titrimetry and LC-MS analyses. The results showed that in the
+absence of Ag(I) ionic catalyst, the degradation of NPE 10 by MEO was 85.93 %.
+Furthermore, when the Ag(I) ionic catalyst was applied, the performance of MEO
+in degradation of NPE 10 was improved to 95.12 %. The back titration using
+Ba(OH)2 confirmed the formation of CO2 by 46.79 %. Whereas the redox titration
+shows the total of degradation organic compounds by 42.50 %, which was
+emphasized by formation of two new peaks in LC-MS chromatogram. In summary, our
+results confirm the potential of MEO technology for NPE-10 degradation.",2012.11838v1
+2021-01-08,The Impact of Bacteria Exposure on the Plasmonic Response of Silver Nanostructured Surfaces,"Silver, especially in the form of nanostructures, is widely employed as an
+antimicrobial agent in a large range of commercial products. The origin of the
+biocidal mechanism has been elucidated in the last decades, and most likely
+originates from silver cation release due to oxidative dissolution followed by
+cellular uptake of silver ions, a process that causes a severe disruption of
+bacterial metabolism and eventually leads to eradication. Despite the large
+number of works dealing with the effects of nanosilver shape/size on the
+antibacterial mechanism and on the (bio)physical chemistry pathways that drive
+bacterial eradication, little effort has been devoted to the investigation of
+the silver NPs plasmon response upon interaction with bacteria. Here we present
+a detailed investigation of the bacteria-induced changes of the plasmon
+spectral and dynamical features after exposure to one of the most studied
+bacterial models, Escherichia Coli. Ultrafast pump-probe measurements indicate
+that the dramatic changes on particle size/shape and crystallinity, which stem
+from a bacteria-induced oxidative dissolution process, translate into a clear
+modification of the plasmon spectral and dynamical features. This study may
+open innovative new avenues in the field of biophysics of bio-responsive
+materials, with the aim of providing new and reliable biophysical signatures of
+the interaction of these materials with complex biological environments.",2101.02926v1
+2021-01-14,Superconducting dome with $extended$ $s$-$wave$ pairing symmetry in the heavily hole-overdoped copper-oxide planes,"We analyze the two-orbital (with $d_{x^2-y^2}$ and $d_{3z^2-r^2}$ orbitals)
+analogue of the $t$-$J$-$U$ model as applied to the description of the
+copper-oxide monolayer deposited on the Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$
+substrate (CuO$_2$/BSCCO). We show, that an $extended$ $s$-$wave$
+superconducting dome appears in the heavily hole overdoped regime of the model,
+with dominant contribution to the pairing coming from the $d_{3z^2-r^2}$
+orbitals. Also, the lower critical doping for the appearance of the SC state
+concurs with the Lifshitz Transition after which the hole-like Fermi pockets
+are created around the $M$ points in the Brillouin zone. The obtained results
+are in accord with the recent experimental result [cf. Y. Zhong et al., Sci.
+Bull. 61, 1239 (2016)]. An analogous two-band description is also analyzed in
+the context of the Ba$_2$CuO$_{4-y}$ bulk compound, where the heavily
+hole-overdoped situation is believed to be reached [cf. W. M. Li et al. PNAS
+116, 12156 (2019)]. As we show, a two dome structure can be realized in such
+system with the $d$- and $s$-$wave$ symmetries of the gap corresponding to the
+low hole-doping and heavily hole overdoped cases, respectively.",2101.05503v1
+2021-01-25,Homogeneous superconducting gap in DBCO synthesized by oxide molecular beam epitaxy,"Much of what is known about high-temperature cuprate superconductors stems
+from studies based on two surface analytical tools, angle-resolved
+photoemission spectroscopy (ARPES) and spectroscopic imaging scanning tunneling
+microscopy (SI-STM). A question of general interest is whether and when the
+surface properties probed by ARPES and SI-STM are representative of the
+intrinsic properties of bulk materials. We find this question is prominent in
+thin films of a rarely studied cuprate DBCO. We synthesize DBCO films by oxide
+molecular beam epitaxy and study them by in situ ARPES and SI-STM. Both ARPES
+and SI-STM show that the surface DBCO layer is different from the bulk of the
+film. It is heavily underdoped, while the doping level in the bulk is close to
+optimal doping evidenced by bulk-sensitive mutual inductance measurements.
+ARPES shows the typical electronic structure of a heavily underdoped CuO2 plane
+and two sets of one-dimensional bands originating from the CuO chains with one
+of them gapped. SI-STM reveals two different energy scales in the local density
+of states, with one corresponding to the superconductivity and the other one to
+the pseudogap. While the pseudogap shows large variations over the length scale
+of a few nanometers, the superconducting gap is very homogeneous. This
+indicates that the pseudogap and superconductivity are of different origins.",2101.10303v1
+2021-01-28,"Oxidation stability of confined linear carbon chains, carbon nanotubes, and graphene nanoribbons as 1D nanocarbons","Three typical one-dimensional (1D)/quasi-1D nanocarbons, linear carbon
+chains, carbon nanotubes, and graphene nanoribbons have been proven to grow
+inside single-wall carbon nanotubes. This gives rise to three types of hybrid
+materials whose behaviour and properties compared among each other are far from
+understood. After proving successful the synthesis of these nanostructured
+materials in recently published work, we have now been able to study their
+oxidation stability systematically by using resonance Raman spectroscopy.
+Surprisingly, the linear carbon chains, which have been theoretically predicted
+to be very unstable, are actually thermally stable up to 500 {\deg}C assisted
+by the protection of the carbon nanotube hosts. Besides, longer linear carbon
+chains inside narrower CNTs are more stable than the shorter ones inside larger
+tubes, suggesting that the thermal stability not only depends on the length of
+linear carbon chains alone, but it is correlated with the confinement of the
+host tubes in a more complicated manner. In addition, graphene nanoribbons come
+overall in view as the most stable confined structures. On the other hand,
+peculiarities like the higher stability of the (6,5) CNT over its (6,4)
+counterpart allow this study to provide a solid platform for further studies on
+the application of these 1D nanocarbons (including true 1D linear carbon
+chains) at ambient conditions.",2101.11752v1
+2021-01-29,Electrochemical tuning of alcohol oxidase and dehydrogenase catalysis via biosensing towards butanol-1 detection in fermentation media,"A novel approach for electrochemical tuning of alcohol oxidase (AOx) and
+alcohol dehydrogenase (ADH) biocatalysis towards butanol-1 oxidation by
+incorporating enzymes in various designs of amperometric biosensors is
+presented. The biosensors were developed by using commercial graphene
+oxide-based screen-printed electrodes and varying enzyme producing strains,
+encapsulation approaches (layer-by-layer (LbL) or one-step electrodeposition
+(EcD)), layers composition and structure, operating conditions (applied
+potential values) and introducing mediators (Meldola Blue and Prussian Blue) or
+Pd-nanoparticles (Pd-NPs). Simultaneous analysis/screening of multiple crucial
+system parameters during the enzyme engineering process allowed to identify
+within a period of one month that four out of twelve proposed designs
+demonstrated a good signal reproducibility and linear response (up to 14.6 mM
+of butanol) under very low applied potentials (from -0.02 to -0.32 V). Their
+mechanical stability was thoroughly investigated by multi-analytical techniques
+prior to butanol determination in cell-free samples from an anaerobic butanol
+fermentation. The EcD-based biosensor that incorporates ADH, NAD+, Pd-NPs and
+Nafion showed no loss of enzyme activity after preparation and demonstrated
+capabilities towards low potential (-0.12 V) detection of butanol-1 in
+fermentation medium (4 mM) containing multiple electroactive species with
+almost 15 times enhanced sensitivity (0.2282 $\mu$A/mM $\pm$ 0.05) when
+compared to the LbL design. Furthermore, the ADH-Nafion bonding for the S.
+cerevisiae strain was confirmed to be 3 times higher than for E. coli.",2101.12350v1
+2017-05-16,Modelling the descent of nitric oxide during the elevated stratopause event of January 2013,"Using simulations with a whole-atmosphere chemistry-climate model nudged by
+meteorological analyses, global satellite observations of nitrogen oxide (NO)
+and water vapour by the Sub-Millimetre Radiometer instrument (SMR), of
+temperature by the Microwave Limb Sounder (MLS), as well as local radar
+observations, this study examines the recent major stratospheric sudden warming
+accompanied by an elevated stratopause event (ESE) that occurred in January
+2013. We examine dynamical processes during the ESE, including the role of
+planetary wave, gravity wave and tidal forcing on the initiation of the descent
+in the mesosphere-lower thermosphere (MLT) and its continuation throughout the
+mesosphere and stratosphere, as well as the impact of model eddy diffusion. We
+analyse the transport of NO and find the model underestimates the large descent
+of NO compared to SMR observations. We demonstrate that the discrepancy arises
+abruptly in the MLT region at a time when the resolved wave forcing and the
+planetary wave activity increase, just before the elevated stratopause reforms.
+The discrepancy persists despite doubling the model eddy diffusion. While the
+simulations reproduce an enhancement of the semi-diurnal tide following the
+onset of the 2013 SSW, corroborating new meteor radar observations at high
+northern latitudes over Trondheim (63.4$^{\circ}$N), the modelled tidal
+contribution to the forcing of the mean meridional circulation and to the
+descent is a small portion of the resolved wave forcing, and lags it by about
+ten days.",1705.05706v1
+2017-05-21,Post trimming of silicon photonics microresonators by nanoscale flash memory technology,"Flash memory technology is widely common in modern microelectronics, and is
+essentially affecting our daily life. Considering the recent progress in
+photonic circuitry, and in particular silicon photonics circuitry, there is now
+an opportunity to embed the flash memory technology in photonic applications. A
+particularly promising candidate that can benefit from such integration is the
+photonic resonator. As of today, chip scale resonators are essential building
+blocks in modern silicon photonic platform. However, their properties, and in
+particular their resonance frequencies deviate from their designed values due
+to unavoidable fabrication imperfections, imposing a stringent limitation on
+the applicability of such devices. Here we present a solution for this major
+obstacle and demonstrate electrical approach for post trimming of such
+resonators. This is achieved by integrating the well-established flash memory
+technology into the photonic circuitry. More specifically, we use the nanoscale
+Silicon-Oxide-Nitride-Oxide-Silicon (SONOS) structure in order to trap charges
+in the thin silicon nitride layer, which is located in close proximity to the
+silicon device layer. This enables the accumulation of charges in the silicon,
+modifying the effective index of the optical mode and consequently the
+resonance frequency. By doing so, we provide a robust and elegant CMOS
+compatible memory solution, which can be easily manufactured and
+commercialized. We expect such an approach to pave the way for even more
+efficient utilization of resonators and interferometers in chip scale photonic
+and electro optic systems, with wide range of applications such as filters,
+modulators, sensors, and lasers, to name a few.",1705.08290v1
+2017-05-30,"Synthesis, characterization and computational simulation of graphene nanoplatelets stabilized in poly(styrene sulfonate) sodium salt","The production of large area interfaces and the use of scalable methods to
+build-up designed nanostructures generating advanced functional properties are
+of high interest for many materials science applications. Nevertheless, large
+area coverage remains a major problem for pristine graphene and here we present
+a hybrid, composite graphene-like material soluble in water, which can be
+exploited in many areas, such as energy storage, electrodes fabrication,
+selective membranes and biosensing. Graphene oxide (GO) was produced by the
+traditional Hummers method being further reduced in the presence of
+poly(styrene sulfonate) sodium salt (PSS), thus creating stable reduced
+graphene oxide (rGO) nanoplateles wrapped by PSS (GPSS). Molecular dynamics
+simulations were carried out of further clarify the interactions between PSS
+molecules and rGO nanoplatelets, with calculations supported by FTIR analysis.
+The intermolecular forces between rGO nanoplatelets and PSS lead to the
+formation of a hybrid material (GPSS) stabilized by van der Waals forces,
+allowing the fabrication of high quality layer-by-layer (LbL) films with
+polyalillamine hydrochloride (PAH). Raman and electrical characterizations
+corroborated the successful modifications in the electronic structures from GO
+to GPSS after the chemical treatment, resulting in (PAH/GPSS) LbL films four
+orders of magnitude more conductive than (PAH/GO).",1705.10673v1
+2017-09-14,Water nanoelectrolysis: A simple model,"A simple model of water nanoelectrolysis-defined as the nanolocalization at a
+single point of any electrolysis phenomenon-is presented. It is based on the
+electron tunneling assisted by the electric field through the thin film of
+water molecules ($\sim$0.3 nm thick) at the surface of a tip-shaped
+nanoelectrode (micrometric to nanometric curvature radius at the apex). By
+applying, e.g., an electric potential V 1 during a finite time t 1 , and then
+the potential --V 1 during the same time t 1 , we show that there are three
+distinct regions in the plane (t 1 , V 1): one for the nanolocalization (at the
+apex of the nanoelectrode) of the electrolysis oxidation reaction, the second
+one for the nanolocalization of the reduction reaction, and the third one for
+the nanolocalization of the production of bubbles. These parameters t 1 and V 1
+completely control the time at which the electrolysis reaction (of oxidation or
+reduction) begins, the duration of this reaction, the electrolysis current
+intensity (i.e., the tunneling current), the number of produced O 2 or H 2
+molecules, and the radius of the nanolocalized bubbles. The model is in good
+agreement with our experiments.",1709.04827v2
+2017-07-29,Optimizing Thermochromism of Solution-Processed VO$_2$ Nanocomposite Films for Chromogenic Fenestration,"Vanadium (IV) oxide is one of the most promising materials for thermochromic
+films due to its unique, reversible crystal phase transition from monoclinic
+(M1) to rutile (R) at its critical temperature (T$_c$) which corresponds to a
+change in optical properties: above T$_c$, VO$_2$ films exhibit a decreased
+transmittance for wavelengths of light in the near-infrared region. However, a
+high transmittance modulation often sacrifices luminous transmittance which is
+necessary for commercial and residential applications of this technology. In
+this study, we explore the potential for synthesis of VO$_2$ films in a matrix
+of metal oxide nanocrystals, using In$_2$O$_3$, TiO$_2$, and ZnO as diluents.
+We seek to optimize the annealing conditions to yield desirable optical
+properties. Although the films diluted with TiO$_2$ and ZnO failed to show
+transmittance modulation, those diluted with In$_2$O$_3$ exhibited strong
+thermochromism. Our investigation introduces a novel window film consisting of
+a 0.93 metal ionic molar ratio VO$_2$-In$_2$O$_3$ nanocrystalline matrix,
+demonstrating a significant increase in luminous transmittance without any
+measurable impact on thermochromic character. Furthermore, solution-processing
+mitigates costs, allowing this film to be synthesized 4x-7x cheaper than
+industry standards. This study represents a crucial development in film
+chemistry and paves the way for further application of VO$_2$ nanocomposite
+films in chromogenic fenestration.",1709.06944v1
+2017-09-21,Impacts of Surface Depletion on the Plasmonic Properties of Doped Semiconductor Nanocrystals,"Degenerately doped semiconductor nanocrystals (NCs) exhibit a localized
+surface plasmon resonance (LSPR) in the infrared range of the electromagnetic
+spectrum. Unlike metals, semiconductor NCs offer tunable LSPR characteristics
+enabled by doping, or via electrochemical or photochemical charging. Tuning
+plasmonic properties through carrier density modulation suggests potential
+applications in smart optoelectronics, catalysis, and sensing. Here, we
+elucidate fundamental aspects of LSPR modulation through dynamic carrier
+density tuning in Sn-doped Indium Oxide NCs. Monodisperse Sn-doped Indium Oxide
+NCs with various doping level and sizes were synthesized and assembled in
+uniform films. NC films were then charged in an in situ electrochemical cell
+and the LSPR modulation spectra were monitored. Based on spectral shifts and
+intensity modulation of the LSPR, combined with optical modeling, it was found
+that often-neglected semiconductor properties, specifically band structure
+modification due to doping and surface states, strongly affect LSPR modulation.
+Fermi level pinning by surface defect states creates a surface depletion layer
+that alters the LSPR properties; it determines the extent of LSPR frequency
+modulation, diminishes the expected near field enhancement, and strongly
+reduces sensitivity of the LSPR to the surroundings.",1709.07136v2
+2017-09-21,Effect of nanostructure on thermoelectric properties of La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ in 300-600 K range,"In oxide materials, nanostructuring effect has been found very promising
+approach for the enhancement of \textit{figure-of-merit}, \textit{ZT}. In the
+present work, we have synthesized La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ (LSMO) compound
+using sol-gel method and samples of crystallite size of 34, 41, and 49 nm were
+obtained by giving different heat treatment. Seebeck coefficient ($\alpha$),
+electrical resistivity ($\rho$), and thermal conductivity ($\kappa$)
+measurements were carried out in 300-600 K temperature range. The systematic
+change in the values of $\alpha$ from $\sim$ -19 $\mu$V/K to $\sim$ -24
+$\mu$V/K and drastic reduction in the values of $\kappa$ from $\sim$0.88 W/mK
+to $\sim$0.23 W/mK are observed as crystallite size is reduced from 49 nm to 34
+nm at $\sim$600 K. Also, fall in the values of $\rho$ in the paramagnetic (PM)
+insulator phase (400-600 K) are effectively responsible for the increasing
+trend in the values of \textit{ZT} at high temperature. For the crystallite
+size of 41 nm, value of \textit{ZT} at 600 K was found to be $\sim$0.017, which
+can be further increased up to $\sim$0.045 around 650 K temperature. The
+predicted value of \textit{ZT} suggests that LSMO can be suitable oxide
+material for thermoelectric applications at high temperature.",1709.07205v2
+2017-07-19,Pharmacokinetics and Molecular Docking studies of Plant-Derived Natural Compounds to Exploring Potential Anti-Alzheimer Activity,"Alzheimer disease (AD) is the leading cause of dementia, accounts for 60 to
+80 percent cases. Two main factors called beta amyloid plaques and tangles are
+prime suspects in damaging and killing nerve cells. However, oxidative stress,
+the process which produces free radicals in cells, is believed to promote its
+progression to the extent that it may responsible for the cognitive and
+functional decline observed in AD. As of today there are few FDA approved drugs
+in the market for treatment, but their cholinergic adverse effect, potentially
+distressing toxicity and limited targets in AD pathology limits their use.
+Therefore, it is crucial to find an effective compounds to combat AD. We choose
+45 plant derived natural compounds that have antioxidant properties to slow
+down disease progression by quenching free redicals or promoting endogenous
+antioxidant capacity. However, we performed molecular docking studies to
+investigate the binding interactions between natural compounds and 13 various
+anti Alzheimer drug targets. Three known Cholinesterase inhibitors (Donepezil,
+Galantamine and Rivastigmine) were taken as reference drugs over natural
+compounds for comparison and drug likeness studies. Few of these compounds
+showed good inhibitory activity besides anti oxidant activity. Most of these
+compounds followed pharmacokinetics properties that make them potentially
+promising drug candidates for the treatment of Alzheimer disease.",1709.10374v1
+2017-11-02,Theory of Large Intrinsic Spin Hall Effect in Iridate Semimetals,"We theoretically investigate the mechanism to generate large intrinsic spin
+Hall effect in iridates or more broadly in 5d transition metal oxides with
+strong spin-orbit coupling. We demonstrate such a possibility by taking the
+example of orthorhombic perovskite iridate with nonsymmorphic lattice symmetry,
+SrIrO$_3$, which is a three-dimensional semimetal with nodal line spectrum. It
+is shown that large intrinsic spin Hall effect arises in this system via the
+spin-Berry curvature originating from the nearly degenerate electronic spectra
+surrounding the nodal line. This effect exists even when the nodal line is
+gently gapped out, due to the persistent nearly degenerate electronic
+structure, suggesting a distinct robustness. The magnitude of the spin Hall
+conductivity is shown to be comparable to the best known example such as doped
+topological insulators and the biggest in any transition metal oxides. To gain
+further insight, we compute the intrinsic spin Hall conductivity in both of the
+bulk and thin film systems. We find that the geometric confinement in thin
+films leads to significant modifications of the electronic states, leading to
+even bigger spin Hall conductivity in certain cases. We compare our findings
+with the recent experimental report on the discovery of large spin Hall effect
+in SrIrO$_3$ thin films.",1711.00861v1
+2017-11-08,Low-loss Tunable 1-D ITO-slot Photonic Crystal Nanobeam Cavity,"Tunable optical material properties enable novel applications in both
+versatile metamaterials and photonic components including optical sources and
+modulators. Transparent conductive oxides (TCOs) are able to highly tune their
+optical properties with applied bias via altering their free carrier
+concentration and hence plasma dispersion. The TCO material indium tin oxide
+(ITO) exhibits unity-strong index changes, and epsilon-near-zero behavior.
+However, with such tuning the corresponding high optical losses, originating
+from the fundamental Kramers-Kronig relations, result in low cavity finesse.
+However, achieving efficient tuning in ITO-cavities without using light matter
+interaction enhancement techniques such as polaritonic modes, which are
+inherently lossy, is a challenge. Here we discuss a novel one-dimensional
+photonic crystal nanobeam cavity to deliver a cavity system offering a wide
+range of resonance tuning range, while preserving physical compact footprints.
+We show that a vertical Silicon-slot waveguide incorporating an actively
+gated-ITO layer delivers ~3.4 nm of tuning. By deploying distributed feedback,
+we are able to keep the Q-factor moderately high with tuning. Combining this
+with the sub-diffraction limited mode volume (0.1 ({\lambda}/2n)3) from the
+photonic (non-plasmonic) slot waveguide, facilitates a high Purcell factor
+exceeding one thousand. This strong light-matter-interaction shows that
+reducing the mode volume of a cavity outweighs reducing the losses in
+diffraction limited modal cavities such as those from bulk Si3N4. These tunable
+cavities enable future modulators and optical sources such as tunable lasers.",1711.02945v1
+2017-11-08,Solution processable and optically switchable 1D photonic structures,"In this work, we report the first demonstration of a solution processable,
+optically switchable 1D photonic crystal by implementing phototunable doped
+metal oxide nanocrystals. The resulting device structure shows bi-photonic
+response with the photonic bandgap covering the visible spectral range and the
+plasmon resonance of the doped metal oxide the near infrared. By means of a
+facile photodoping process, we tuned the plasmonic response and switched
+effectively the optical properties of the photonic crystal, translating the
+effect from the near infrared to the visible. The ultrafast bandgap pumping
+induces a signal change in the region of the photonic stopband, with recovery
+times of several picoseconds, providing a step toward the ultrafast optical
+switching. Optical modeling uncovers the importance to understand largely the
+variations of the dielectric function of the photodoped material, and
+variations in the high frequency region of the Drude response are responsible
+for the strong switching in the visible after photodoping. Our device
+configuration offers unprecedented tunablility due to flexibility in device
+design, cover wavelength ranges from the visible to the near infrared. Our
+findings indicate a new protocol to modify the optical response of photonic
+devices by optical triggers only.",1711.03192v1
+2017-11-09,Gas-Phase Spectra of MgO Molecules: A Possible Connection from Gas-Phase Molecules to Planet Formation,"A more fine-tuned method for probing planet-forming regions, such as
+protoplanetary discs, could be rovibrational molecular spectroscopy observation
+of particular premineral molecules instead of more common but ultimately less
+related volatile organic compounds. Planets are created when grains aggregate,
+but how molecules form grains is an ongoing topic of discussion in astrophysics
+and planetary science. Using the spectroscopic data of molecules specifically
+involved in mineral formation could help to map regions where planet formation
+is believed to be occurring in order to examine the interplay between gas and
+dust. Four atoms are frequently associated with planetary formation: Fe, Si,
+Mg, and O. Magnesium, in particular, has been shown to be in higher relative
+abundance in planet-hosting stars. Magnesium oxide crystals comprise the
+mineral periclase making it the chemically simplest magnesium-bearing mineral
+and a natural choice for analysis. The monomer, dimer, and trimer forms of
+(MgO)_n with n = 1 - 3 are analyzed in this work using high-level quantum
+chemical computations known to produce accurate results. Strong vibrational
+transitions at 12.5 {\mu}m, 15.0 {\mu}m, and 16.5 {\mu}m are indicative of
+magnesium oxide monomer, dimer, and trimer making these wavelengths of
+particular interest for the observation of protoplanetary discs and even
+potentially planet-forming regions around stars. If such transitions are
+observed in emission from the accretion discs or absorptions from stellar
+spectra, the beginning stages of mineral and, subsequently, rocky body
+formation could be indicated.",1711.03544v1
+2017-11-12,Layer-by-Layer Assembly of Efficient Flame Retardant Coatings Based On High Aspect Ratio Graphene Oxide and Chitosan Capable of Preventing Ignition of PU Foam,"The layer-by-layer (LbL) technique is adopted for the construction of
+multilayers encompassing chitosan and graphene oxide (GO) platelets capable of
+improving the flame retardant properties open cell PU foams. The LbL assembly
+follows a linear growth regime as evaluated by infrared spectroscopy and yields
+a multilayer structure where GO platelets are embedded within a chitosan
+continuous matrix. 3 and 6 bi-layers (BL) can efficiently coat the complex 3D
+structure of the foam and substantially improve its flame retardant properties.
+3BL only add 10% to the original mass and can suppress the melt dripping during
+flammability and reduce both the peak of heat release rate by 54% and the total
+smoke released by 59% in forced combustion tests. Unprecedented among other LbL
+assemblies employed for FR purposes, the deposition 6BL is capable of slowing
+down the release of combustible volatile to the limits of non-ignitability thus
+preventing ignition in half of the specimens during cone calorimetry tests.
+This has been ascribed to the formation of a protective coating where the
+thermally stable char produced by chitosan serves as a continuous matrix
+embedding GO platelets, which control volatile release while mechanically
+sustaining the PU foam structure.",1711.04318v2
+2017-11-27,"A ferroelectric liquid crystal confined in cylindrical nanopores: Reversible smectic layer buckling, enhanced light rotation and extremely fast electro-optically active Goldstone excitations","The orientational and translational order of a thermotropic ferroelectric
+liquid crystal (2MBOCBC) imbibed in self-organized, parallel, cylindrical pores
+with radii of 10, 15, or 20 nm in anodic aluminium oxide monoliths (AAO) are
+explored by high-resolution linear and circular optical birefringence as well
+as neutron diffraction texture analysis. The results are compared to
+experiments on the bulk system. The native oxidic pore walls do not provide a
+stable smectogen wall anchoring. By contrast, a polymeric wall grafting
+enforcing planar molecular anchoring results in a thermal-history independent
+formation of smectic C* helices and a reversible chevron-like layer buckling.
+An enhancement of the optical rotatory power by up to one order of magnitude of
+the confined compared to the bulk liquid crystal is traced to the
+pretransitional formation of helical structures at the smectic-A*-to-smectic-C*
+transformation. A linear electro-optical birefringence effect evidences
+collective fluctuations in the molecular tilt vector direction along the
+confined helical superstructures, i.e. the Goldstone phason excitations typical
+of the para-to-ferroelectric transition. Their relaxation frequencies increase
+with the square of the inverse pore radii as characteristic of plane-wave
+excitations and are two orders of magnitude larger than in the bulk, evidencing
+an exceptionally fast electro-optical functionality of the
+liquid-crystalline-AAO nanohybrids.",1711.09673v1
+2017-11-29,Electron-Hole Separation in Ferroelectric Oxides for Efficient Photovoltaic Responses,"Despite their potential to exceed the theoretical Shockley-Queisser limit,
+ferroelectric photovoltaics (FPVs) have performed inefficiently due to their
+extremely low photocurrents. Incorporating Bi2FeCrO6 (BFCO) as the light
+absorber in FPVs has recently led to impressively high and record photocurrents
+[Nechache et al. Nature Photon. 2015, 9, 61], reviving the FPV field. However,
+our understanding of this remarkable phenomenon is far from satisfactory. Here,
+we use first-principles calculations to determine that such excellent
+performance mainly lies in the efficient separation of electron-hole (e-h)
+pairs. We show that photoexcited electrons and holes in BFCO are spatially
+separated on the Fe and Cr sites, respectively. This separation is much more
+pronounced in disordered BFCO phases, which show exceptional PV responses. We
+further set out to design a strategy for next-generation FPVs, not limited to
+BFCO, by exploring 44 additional Bi-based double-perovskite oxides. We suggest
+9 novel active-layer materials that can offer strong e-h separations and a
+desired band gap energy for application in FPVs. Our work indicates that charge
+separation is the most important issue to be addressed for FPVs to compete with
+conventional devices.",1711.10979v1
+2018-05-31,Electrochemical tuning of capacitive response of graphene oxide,"Increasing energy demands of modern society requires deep understanding of
+the properties of energy storage materials as well as their performance tuning.
+We show that the capacitance of graphene oxide (GO) can be precisely tuned
+using a simple electrochemical reduction route. In situ resistance
+measurements, combined with cyclic voltammetry measurement and Raman
+spectroscopy, have shown that upon the reduction GO is irreversibly
+deoxygenated which is further accompanied with structural ordering and
+increasing of electrical conductivity. The capacitance is maximized when the
+concentration of oxygen functional groups is properly balanced with the
+conductivity. Any further reduction and de-oxygenation leads to the gradual
+loss of the capacitance. The observed trend is independent on the preparation
+route and on the exact chemical and structural properties of GO. It is proposed
+that an improvement of capacitive properties of any GO can be achieved by
+optimization of its reduction conditions.",1806.00130v2
+2018-06-30,Study and characterization of SrTiO3 surface,"The two-dimensional electron gas (2DEG) at oxides interfaces and surfaces has
+attracted large attention in physics and research due to its unique electronic
+properties and possible application in optoelectronics and nanoelectronics. The
+origin of 2DEGes at oxide interfaces has been attributed to the well known
+""polar catastrophe"" mechanism. On the other hand, recently a 2DEG was also
+found on a clean SrTiO3(001) surface where it is formed due to oxygen
+vacancies. However, these 2DEG systems have been until now found mostly on
+atomically perfect crystalline samples usually grown by pulsed laser deposition
+or molecular beam epitaxy i.e. samples which are difficult to be prepared and
+require specific experimental conditions. Here, we report on the fabrication of
+SrTiO3 thin films deposited by magnetron sputtering which is suitable for
+mass-production of samples adapted for nanoelectronic applications. The
+characterization of their structural and electronic properties was done and
+compared to those of SrTiO3 single crystals. XRD patterns and SEM micrography
+show that the deposited films are amorphous and their structure changes to
+polycrystalline by heating them at 900 {\deg}C. Photoemission spectroscopy (XPS
+and UPS) was used to study the electronic properties of the films and the
+crystal. In both, we observe the 2DEG system at Fermi level and the formation
+of Ti3+ states after heating the surface at 900 {\deg}C.",1807.00150v1
+2018-07-03,Comparison of the Thermospheric Nitric Oxide Emission Observations and the Global Ionosphere-Thermosphere Model (GITM) Simulations: Sensitivity to Solar and Geomagnetic Activities,"An accurate estimate of the energy budget (heating and cooling) of the
+ionosphere and thermosphere, especially during space weather events, has been a
+challenge. The abundance of Nitric Oxide (NO), a minor species in the
+thermosphere, is an important component of energy balance here because its
+production comes from energy sources able to break the strong bond of molecular
+nitrogen, and infrared emissions from NO play an important role in
+thermospheric cooling. Recent studies have significantly improved our
+understanding of NO chemistry and its relationship to energy deposition in the
+thermospheric photochemical reactions. In this study, the chemical scheme in
+the Global Ionosphere Thermosphere Model (GITM) is updated to better predict
+the lower thermospheric NO responses to solar and geomagnetic activity. We
+investigate the sensitivity of the 5.3-micron NO emission to F10.7 and Ap
+indices by comparing the global integrated emission from GITM with an empirical
+proxy derived from the Sounding of the Atmosphere using Broadband Emission
+Radiometry measurements. GITM's total emission agrees well within 20% of the
+empirical values. The updated chemistry scheme significantly elevates the level
+of integrated emission compared to the previous scheme. The inclusion of
+N2(A)-related production of NO contributes an additional 5-25% to the emission.
+Localized enhancement of ~70% in column density and a factor of three in column
+emission are simulated at a moderate geomagnetic level.",1807.01380v1
+2018-07-06,Fabrication of Hollow AlAu2 Nanoparticles by Solid State Dewetting and Oxidation of Al on Sapphire Substrate,"The Al-Au binary diffusion couple is a classic example of the system
+exhibiting Kirkendall voiding during interdiffusion. We demonstrate that this
+effect, which is a major reason for failures of the wire bonds in
+microelectronics, can be utilized for producing hollow AlAu2 nanoparticles
+attached to sapphire substrate. To this end, we produced the core-shell Al-Au
+nanoparticles by performing a solid state dewetting treatment of Al thin film
+deposited on sapphire substrate, followed by the deposition of thin Au layer on
+the top of dewetted sample. Annealing of the core-shell nanoparticles in air
+resulted in outdiffusion of Al from the particles, formation of pores, and
+growth of the AlAu2 intermetallic phase in the particles. We demonstrated that
+the driving force for hollowing is the oxidation reaction of the Al atoms at
+the Au-sapphire interface, leading to the homoepitaxial growth of newly formed
+alumina at the interface. We developed a kinetic model of hollowing controlled
+by diffusion of oxygen through the Au thin film, and estimated the solubility
+of oxygen in solid Au. Our work demonstrates that the core-shell nanoparticles
+attached to the substrate can be hollowed by the Kirkendall effect in the thin
+film spatially separated from the particles.",1807.02279v2
+2018-07-06,Nitric Oxide in Climatological Global Energy Budget During 1982-2013,"Over the past decades, temperature and density of the upper atmosphere show
+negative trends and decrease of the upper atmospheric temperature is attributed
+to the declining neutral density. Specifically, nitric oxide (NO) and carbon
+dioxide (CO2) govern thermospheric cooling at 5.3 and 15 micron, respectively.
+While a lot of efforts have focused on the CO2 effects on the long-term trends,
+relatively less attention has been paid to the impacts by NO, which responds to
+solar and geomagnetic activities dynamically. In this study, we investigate the
+role of NO in climatological global energy budget for the recent three solar
+cycles using the Global Ionosphere Thermosphere Model. From 1982 to 2013, the
+F10.7 and Ap indices showed a decadal decrease of ~8% and ~20%, respectively.
+By imposing temporal-varying F10.7 and Ap values in the simulations, we find a
+decadal change of -0.28x1011 W or -17.3% in total NO cooling power, which
+agrees well with that (-0.34x1011 W or -17.2%) from the empirical Thermosphere
+Climate Index derived from the TIMED/SABER data. Neutral density decreases by
+10-20% at 200-450km and Tex decreases by 25.3 K per decade. The deduced-decadal
+change of NO cooling reaches ~25% of the sum of total heating at ~130 km and
+its significance decreases with altitude.",1807.02495v1
+2018-07-23,Effect of Fluoropolymer Composition on Topochemical Synthesis of SrMnO$_{3-δ}$F$_{γ}$ Oxyfluoride Films,"We report the synthesis of SrMnO$_{3-{\delta}}$F$_{{\gamma}}$ perovskite
+oxyfluoride thin films using a vapor transport method to fluorinate as-grown
+SrMnO$_{2.5}$ epitaxial thin films. The influence of the fluoropolymer, which
+acts as a fluorine vapor source, was investigated by utilizing polyvinyl
+fluoride (PVF), polyvinylidene difluoride (PVDF) and polytetrafluoroethylene
+(PTFE) in the reaction. The same process was carried out with polyethylene (PE)
+to isolate the role of carbon in the vapor transport process. The F
+distribution was probed by X-ray photoemission spectroscopy, which confirmed
+the incorporation of F into the films and revealed higher F concentrations in
+films exposed to PVF and PVDF compared to PTFE. The c-axis parameter expands
+after fluorination, a result consistent with density functional theory
+calculations that attribute the volume expansion to elongated Mn-F bonds
+compared to shorter Mn-O bonds. Using X-ray absorption spectroscopy, we show
+that the fluorination process reduces the nominal Mn oxidation state suggesting
+that F substitutes on O sites in the lattice as opposed to filling anion
+vacancy sites, a finding further supported by calculated formation energies of
+different F site occupancies. These results provide new insights into
+topochemical fluorination of perovskite oxides, which should enable future
+synthesis and design efforts focused on oxyfluoride heterostructures.",1807.08815v1
+2018-07-26,Expediting hydrogen evolution through topological surface states on Bi2Te3,"Recently, the development of efficient and non-noble metal electrocatalysts
+with excellent durability for the hydrogen evolution reaction (HER) has
+attracted increasing attention. The exotic and robust metallic surface states
+of topological insulators (TIs) are theoretically predicted to enhance surface
+catalytic activity of overlaying catalysts, but no experimental evidence for
+TIs directly used as electrocatalysts has ever been reported. In this work, we
+fabricated the TI thin films of Bi2Te3 with different thicknesses using the
+molecular beam epitaxy method, and found that these thin films exhibit high
+electrocatalytic activity in HER. The 48 nm Bi2Te3 thin film has the best
+performance, which is attributed to its largest active area arising from the
+spiral growth mode of triangular domains as revealed by atomic force microscopy
+imaging. Importantly, our theoretical calculations reveal that while pure
+Bi2Te3 is not a good electrocatalyst, the Bi2Te3 thin films with partially
+oxidized surfaces or Te vacancies have high HER activity. The existence of the
+corresponding surface oxides on the Bi2Te3 thin films is supported by our X-ray
+photoelectron spectroscopy data. Particularly, we demonstrate that the
+topological surface states play a key role in enhancing the HER performance.
+Our study offers a new direction to design cost-effective electrocatalysts.",1807.09957v2
+2018-08-07,Retrieval of nitric oxide in the mesosphere and lower thermosphere from SCIAMACHY limb spectra,"We use the ultra-violet (UV) spectra in the range 230--300 nm from the
+SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY
+(SCIAMACHY) to retrieve the nitric oxide (NO) number densities from atmospheric
+emissions in the gamma-bands in the mesosphere and lower thermosphere. Using
+3-D ray tracing, a 2-D retrieval grid, and regularisation with respect to
+altitude and latitude, we retrieve a whole semi-orbit simultaneously for the
+altitude range from 60 to 160 km.
+  We present details of the retrieval algorithm, first results, and initial
+comparisons to data from the Michelson Interferometer for Passive Atmospheric
+Sounding (MIPAS). Our results agree on average well with MIPAS data and are in
+line with previously published measurements from other instruments. For the
+time of available measurements in 2008--2011, we achieve a vertical resolution
+of 5--10 km in the altitude range 70--140 km and a horizontal resolution of
+about 9{\deg} from 60{\deg}S--60{\deg}N. With this we have independent
+measurements of the NO densities in the mesosphere and lower thermosphere with
+approximately global coverage. This data can be further used to validate
+climate models or as input for them.",1808.02388v1
+2018-08-15,"Electron Localization Enhances Cation Diffusion in Reduced ZrO2, CeO2 and BaTiO3","According to defect chemistry, the experimental observations of enhanced
+cation diffusion in a reducing atmosphere in zirconia, ceria and barium
+titanate are in support of an interstitial mechanism. Yet previous
+computational studies always found a much higher formation energy for cation
+interstitials than for cation vacancies, which would rule out the interstitial
+mechanism. The conundrum has been resolved via first-principles calculations
+comparing migration of reduced cations and oxidized ones, in cubic ZrO2, CeO2
+and BaTiO3. In nearly all cases, reduction alone lowers the migration barrier,
+and pronounced lowering results if cation's electrostatic energy at the saddle
+point decreases. The latter is most effectively realized when a Ti cation is
+allowed to migrate via an empty Ba site thus being fully screened all the way
+by neighboring anions. Since reduction creates oxygen vacancies as well, which
+are highly mobile, we also studied their effect on cation migration, and found
+it only marginally lowers the migration barrier. In several cases, however, a
+large synergistic effect between cation reduction and oxygen vacancy is
+revealed, causing an electron to localize in the saddle-point state at a much
+lower energy than normal, signaling that the saddle point is a negative-U state
+in which the soft environment enables a large electron-phonon interaction that
+can over-compensate the on-site Coulomb repulsion. These general findings are
+expected to be applicable to defect-mediated ion migration in most transitional
+metal oxides.",1808.05198v1
+2018-08-16,A disclosure of the role of frequency on the plasma electrolytic oxidation of AZ31 magnesium alloy in aluminate-tungstate electrolyte,"Plasma electrolytic oxidation (PEO) was carried out to form black ceramic
+coatings on AZ31 magnesium alloy in aluminate-tungstate electrolyte. Influences
+of current frequency (such as 100, 1000 and 2000 Hz) on properties of the PEO
+coatings have been explored. It was found that increment of frequency led to
+coatings with higher thickness, higher roughness and darker appearance. In
+order to explore the coating formation mechanism at different frequencies, the
+micro-discharges at different frequencies were investigated by real-time
+imaging method. Microstructure of coatings was characterized by scanning
+electron microscopy (SEM) assisted with energy dispersive X-ray spectroscopy
+(EDS). Coatings formed at 100 Hz show the most compact microstructure while
+porosity of the coatings, both in the pore number and pore size, is greatly
+increased at higher frequencies. The coatings formed at higher frequencies show
+an increased atomic ratio of W/Al. The cancel of the negative pulse from the
+pulsed waveform can also lead to a higher W/Al ratio, and hence a darker
+coating. The higher porosity of the coatings was attributed to the stronger
+plasma discharges and gas evolution at higher frequencies. The stronger plasma
+discharge is induced by the fact that there is not sufficient time for the
+cooling down of discharge channels at higher frequencies.",1808.06587v1
+2018-10-31,Challenges in materials and devices for Resistive-Switching-based Neuromorphic Computing,"This tutorial describes challenges and possible avenues for the
+implementation of the components of a solid-state system, which emulates a
+biological brain. The tutorial is devoted mostly to a charge-based (i.e.
+electric controlled) implementation using transition metal oxides materials,
+which exhibit unique properties that emulate key functionalities needed for
+this application. In the Introduction, we compare the main differences between
+a conventional computational machine, based on the Turing-von Neumann paradigm,
+to a Neuromorphic machine, which tries to emulate important functionalities of
+a biological brain. We also describe the main electrical properties of
+biological systems, which would be useful to implement in a charge-based
+system. In Chapter II, we describe the main components of a possible
+solid-state implementation. In Chapter III, we describe a variety of Resistive
+Switching phenomena, which may serve as the functional basis for the
+implementation of key devices for Neuromorphic computing. In Chapter IV we
+describe why transition metal oxides, are promising materials for future
+Neuromorphic machines. Theoretical models describing different resistive
+switching mechanisms are discussed in Chapter V while existing implementations
+are described in Chapter VI. Chapter VII presents applications to practical
+problems. We list in Chapter VIII important basic research challenges and open
+issues. We discuss issues related to specific implementations, novel materials,
+devices and phenomena. The development of reliable, fault tolerant, energy
+efficient devices, their scaling and integration into a Neuromorphic computer
+may bring us closer to the development of a machine that rivals the brain.",1812.01120v1
+2018-12-07,A Ferroelectric Semiconductor Field-Effect Transistor,"Ferroelectric field-effect transistors employ a ferroelectric material as a
+gate insulator, the polarization state of which can be detected using the
+channel conductance of the device. As a result, the devices are of potential to
+use in non-volatile memory technology, but suffer from short retention times,
+which limits their wider application. Here we report a ferroelectric
+semiconductor field-effect transistor in which a two-dimensional ferroelectric
+semiconductor, indium selenide ({\alpha}-In2Se3), is used as the channel
+material in the device. {\alpha}-In2Se3 was chosen due to its appropriate
+bandgap, room temperature ferroelectricity, ability to maintain
+ferroelectricity down to a few atomic layers, and potential for large-area
+growth. A passivation method based on the atomic-layer deposition of aluminum
+oxide (Al2O3) was developed to protect and enhance the performance of the
+transistors. With 15-nm-thick hafnium oxide (HfO2) as a scaled gate dielectric,
+the resulting devices offer high performance with a large memory window, a high
+on/off ratio of over 108, a maximum on-current of 862 {\mu}A {\mu}m-1, and a
+low supply voltage.",1812.02933v2
+2018-12-12,Potential jumps at transport bottlenecks cause instability of nominally ionic solid electrolytes in electrochemical cells,"Normal operations of electrochemical devices such as solid oxide fuel cells
+(SOFC), solid oxide electrolyzer cells (SOEC) and lithium ion batteries (LIB)
+sometimes fail because of unexpected formation of internal phases. These phases
+include oxygen bubbles at grain boundaries inside the zirconia electrolyte of
+SOEC, isolated Li metal islands inside the (garnet type) Li7La3Zr2O12
+electrolyte of all-solid-state LIB, and similar Na metal islands inside the
+Na-beta-alumina and NASICON electrolytes of Na-S batteries. Remarkably,
+although the devices can operate in both polarities, the propensity for failure
+depends on the polarity. Here we explain these and other phenomena in nominally
+ionic solid electrolytes and mixed-conducting electrodes in simple
+thermodynamic and kinetic terms: the unexpected internal phases are caused by a
+large potential jump that is needed to push a constant ion or electron flow
+through its internal transport bottleneck. Definite rules for internal phase
+formation including its polarity dependence are formulated to help predict and
+mitigate it, which leads to microstructural instability, efficiency
+deterioration and breakdown.",1812.05187v5
+2018-12-18,A hybrid silicon-sapphire cryogenic Fabry-Perot cavity using hydroxide catalysis bonding,"The third-generation gravitational wave detectors are under development by
+operating the detector in cryogenic temperature to reduce the thermal noise.
+Silicon and sapphire are promising candidate materials for the test masses and
+suspension elements due to their remarkable mechanical and thermal properties
+at cryogenic temperature. Here we present the performances of the cryogenic
+thermal cycling and strength testing on hydroxide catalysis bonding between
+sapphire and silicon. Our results suggest that although these two materials
+have very different coefficients of thermal expansion, but if the flatness and
+the thermally grown $\mathrm{SiO_2}$ oxidation layer on the silicon surface are
+controlled well, the bonded samples can still survive thermal cycling from room
+temperature to 5.5 K. A breaking strength of 3.6$\pm 0.6$ MPa is measured for
+the bonds between sapphire and silicon with a 190 nm silicon oxidation
+thickness after cooling cycle. We construct a hybrid sapphire-silicon
+Fabry-Perot cavity with the developing bonding technique in our lab. The
+measurement results reveal that the cavity can survive repeated thermal cycling
+while maintaining a good finesse.",1812.07347v1
+2018-12-27,Molecular dynamics analysis of adsorption process of anti-copper-corrosion additives to the copper surface,"As a model system of the adsorption process of anti-corrosion additives on a
+metal surface, molecular dynamics simulations of benzotriazole (BTA) molecules
+with copper slabs were completed. As a force field, ReaxFF was used to simulate
+both adsorption dynamics and the charge transfer on the solid surface. Two
+simulations are presented. In order to investigate the physical adsorption on
+the surface, the simulation was done for the adsorption process of BTA
+molecules on the copper (II) oxide slab. BTA molecules formed on adsorbed layer
+in parallel to the surface, and aggregation of the molecules due to the surface
+diffusion was found. In order to investigate the selective and chemical
+adsorption on the surface, a hybrid slab, which has both a copper (Cu) area and
+a copper (I) oxide (Cu2O) area, was used. A selective adsorption phenomenon was
+found. The number of BTA molecules adsorbed on the Cu area is 5 times greater
+than that on the Cu2O area. Detailed dynamics focused on charge transfer showed
+a surface diffusion and enhancement of polarization due to charge transfer from
+the metal surface caused the selective adsorption. In a real phenomenon, the
+reason why a few anti-corrosion additives are able to protect a metal surface
+is postulated to be due to this selective nature of adsorption onto a newly
+formed metal surface.",1812.10647v1
+2018-12-29,A microscopic perspective on heterogeneous catalysis,"A general formalism is presented to describe the turnover frequency (TOF)
+during heterogeneous catalysis beyond a mean field treatment. For every
+elementary reaction we define its multiplicity as the number of times the
+reaction can be performed in the current configuration of the catalyst surface,
+divided by the number of active sites. It is shown that any change in the
+multiplicity with temperature can be directly understood as a modification in
+configurational entropy. Based on this, we determine the probability of
+observing any particular elementary reaction, leading to a procedure for
+identifying any Rate Controlling Step (RCS) as well as the Rate Determining
+Step (RDS), if it exists. Furthermore, it is shown that such probabilities
+provide a thorough description of the overall catalytic activity, enabling a
+deep understanding of the relative importance of every elementary reaction.
+Most importantly, we formulate a simple expression to describe accurately the
+apparent activation energy of the TOF, valid even when adsorbate-adsorbate
+interactions are included, and compare it to previous, approximate expressions,
+including the traditional Temkin formula for typical reaction mechanisms
+(Langmuir-Hinshelwood, Eley-Rideal, etc...). To illustrate the validity of our
+formalism beyond the mean field domain we present Kinetic Monte Carlo
+simulations for two widely-studied and industrially-relevant catalytic
+reactions, namely, the oxidation of CO on RuO$_2$(110) and the selective
+oxidation of NH$_{3}$ on the same catalyst.",1812.11398v1
+2019-01-02,Mott gapping in 3d ABO3 perovskites without Mott-Hubbard interelectronic U,"The existence of band gaps in Mott insulators such as perovskite oxides with
+partially filled 3d shells has been traditionally explained in terms of strong,
+dynamic inter-electronic repulsion codified by the on-site repulsion energy U
+in the Hubbard Hamiltonian. The success of the ""DFT+U approach"" where an
+empirical on-site potential term U is added to the exchange-and correlation
+Density Functional Theory (DFT) raised questions on whether U in DFT+U
+represents interelectronic correlation in the same way as it does in the
+Hubbard Hamiltonian, and if empiricism in selecting U can be avoided. Here we
+illustrate that ab-initio DFT without any U is able to predict gapping trends
+and structural symmetry breaking (octahedra rotations, Jahn-Teller modes, bond
+disproportionation) for all ABO3 3d perovskites from titanates to nickelates in
+both spin-ordered and spin disordered paramagnetic phases. We describe the
+paramagnetic phases as a supercell where individual sites can have different
+local environments thereby allowing DFT to develop finite moments on different
+sites as long as the total cell has zero moment. We use a recently developed
+exchange and correlation functional (""SCAN"") that is sanctioned by the usual
+single-determinant, mean-field DFT paradigm with static correlations, but has a
+more precise rendering of self-interaction cancelation. Our results suggest
+that strong dynamic electronic correlations are not playing a universal role in
+gapping of 3d ABO3 Mott insulators, and opens the way for future applications
+of DFT for studying a plethora of complexity effects that depend on the
+existence of gaps, such as doping, defects, and band alignment in ABO3 oxides.",1901.00425v2
+2019-01-03,Classification of Local Chemical Environments from X-ray Absorption Spectra using Supervised Machine Learning,"X-ray absorption spectroscopy is a premier element-specific technique for
+materials characterization. Specifically, the x-ray absorption near-edge
+structure (XANES) encodes important information about the local chemical
+environment of an absorbing atom, including coordination number, symmetry, and
+oxidation state. Interpreting XANES spectra is a key step towards understanding
+the structural and electronic properties of materials, and as such, extracting
+structural and electronic descriptors from XANES spectra is akin to solving a
+challenging inverse problem. Existing methods rely on empirical fingerprints,
+which are often qualitative or semiquantitative and not transferable. In this
+paper, we present a machine learning-based approach, which is capable of
+classifying the local coordination environments of the absorbing atom from
+simulated K-edge XANES spectra. The machine learning classifiers can learn
+important spectral features in a broad energy range without human bias and once
+trained, can make predictions on the fly. The robustness and fidelity of the
+machine learning method are demonstrated by an average 86% accuracy across the
+wide chemical space of oxides in eight 3d transition-metal families. We found
+that spectral features beyond the preedge region play an important role in the
+local structure classification problem especially for the late 3d
+transition-metal elements.",1901.00788v2
+2019-01-07,Unexplored reactivity of (Sn)2- Oligomers with transition metals in low-temperature solid-state reactions,"Chalcogenides (Q = S, Se, Te), one of the most important family of materials
+in solid-state chemistry, differ from oxides by their ability to form
+covalently-bonded (Qn)2- oligomers. Each chalcogen atom within such entity
+fulfills the octet rule by sharing electrons with other chalcogen atoms but
+some antibonding levels are vacant. This makes these oligomers particularly
+suited for redox reactions in solid state, namely towards elemental metals with
+a low redox potential that may be oxidized. We recently used this strategy to
+design, at low temperature and in an orientated manner, materials with 2D
+infinite layers through the topochemical insertion of copper into preformed
+precursors containing (S2)2- and/or (Se2)2- dimers (i.e. La2O2S2, Ba2F2S2 and
+LaSe2). Herein we extend the validity of the concept to the redox activity of
+(S2)2- and (S3)2- oligomers towards 3d transition metal elements (Cu, Ni, Fe)
+and highlight the strong relationship between the structures of the precursors,
+BaS2 and BaS3, and the products, BaCu2S2, BaCu4S3, BaNiS2 and BaFe2S3. Clearly,
+beyond the natural interest for the chemical reactivity of oligomers to
+generate compounds, this soft chemistry route may conduct to the rational
+conception of materials with a predicted crystal structure.",1901.01907v1
+2019-01-14,Transferable MARTINI Model of Poly(ethylene Oxide),"Motivated by the deficiencies of the previous MARTINI models of poly(ethylene
+oxide) (PEO), we present a new model featuring a high degree of
+transferability. The model is parametrized on (a) a set of 8 free energies of
+transfer of dimethoxyethane (PEO dimer) from water to solvents of varying
+polarity; (b) the radius of gyration in water at high dilution; and (c)
+matching angle and dihedral distributions from atomistic simulations. We
+demonstrate that our model behaves well in five different areas of application:
+(1) it produces accurate densities and phase behavior or small PEO oligomers
+and water mixtures; (2) it yields chain dimensions in good agreement with the
+experiment in three different solvents (water, diglyme, and benzene) over a
+broad range of molecular weights (1.2 kg/mol to 21 kg/mol); (3) it reproduces
+qualitatively the structural features of lipid bilayers containing PEGylated
+lipids in the brush and mushroom regime; (4) it is able to reproduce the phase
+behavior of several PEO-based nonionic surfactants in water; and (5) it can be
+combined with the existing MARTINI PS to model PS/PEO block copolymers.
+Overall, the new PEO model outperforms previous models and features a high
+degree of transferability.",1901.04413v1
+2019-01-17,Stability of Implanted Transition Metal Dopants in Rock-salt Oxides,"Transition metals (TMs) implanted in oxides with rock-salt crystal structures
+(for example MgO and BaO) are assumed to substitute cations (Mg in case of MgO)
+from the lattice sites. We show that not all implanted TMs substitute cations
+but can be stable in interstitial sites as well. Stability of TM (Sc--Zn)
+dopants in various charge states in MgO and BaO has been investigated in the
+framework of density functional theory. We propose an effective way to
+calculate stability of implanted metals that let us predict site preference
+(interstitial or substitution) of the dopant in the host. We find that two
+factors govern the preference for an interstitial site: i) relative ionic
+radius and ii) relative oxygen affinity of cation and the TM dopants. If the
+radius of the cation is much larger than TM dopant, as in BaO, TM atoms always
+sit at interstitial sites. On the other hand, if the radius of the cation is
+comparable to that of the dopant TM, as in case of MgO, the transition of the
+preferred defect site, from substituting lattice Mg atom (Sc to Mn) to
+occupying interstitial site (Fe to Zn) is observed. This transition can be
+attributed to the change in the oxygen affinity of the TM atoms from Sc to Zn.
+Our results also explain experiments on Ni and Fe atoms implanted in MgO. This
+is the first-time we have shown that TM dopants can be stable at interstitial
+sites in stable compounds, which could potentially give rise to exotic
+properties.",1901.05607v2
+2019-01-25,"Tailoring Vanadium Dioxide Film Orientation using Nanosheets: A Combined Microscopy, Diffraction, Transport and Soft X-ray in Transmission Study","VO2 is a much-discussed material for oxide electronics and neuromorphic
+computing applications. Here, heteroepitaxy of vanadium dioxide (VO2) was
+realized on top of oxide nanosheets that cover either the amorphous silicon
+dioxide surfaces of Si substrates or X-ray transparent silicon nitride
+membranes. The out-of-plane orientation of the VO2 thin films was controlled at
+will between (011)M1/(110)R and (-402)M1/(002)R by coating the bulk substrates
+with Ti0.87O2 and NbWO6 nanosheets, respectively, prior to VO2 growth.
+Temperature dependent X-ray diffraction and automated crystal orientation
+mapping in microprobe TEM mode (ACOM-TEM) characterized the high phase purity,
+the crystallographic and orientational properties of the VO2 films. Transport
+measurements and soft X-ray absorption in transmission are used to probe the
+VO2 metal-insulator transition, showing results of a quality equal to those
+from epitaxial films on bulk single-crystal substrates. Successful local
+manipulation of two different VO2 orientations on a single substrate is
+demonstrated using VO2 grown on lithographically-patterned lines of Ti0.87O2
+and NbWO6 nanosheets investigated by electron backscatter diffraction. Finally,
+the excellent suitability of these nanosheet-templated VO2 films for advanced
+lensless imaging of the metal-insulator transition using coherent soft X-rays
+is discussed.",1901.08823v1
+2019-01-30,Meeting the Scaling Challenge for Post-Silicon Nanoelectronics using CaF2 Insulators,"Two-dimensional (2D) semiconductors have been suggested both for
+ultimately-scaled field-effect transistors (FETs) and More-than-Moore
+nanoelectronics. However, these targets can not be reached without accompanying
+gate insulators which are scalable into the nanometer regime. Despite the
+considerable progress in the search for channel materials with high mobilities
+and decent bandgaps, finding high-quality insulators compatible with 2D
+technologies has remained a challenge. Typically used oxides (e.g. SiO2, Al2O3
+and HfO2) are amorphous when scaled, while two-dimensional hBN exhibits
+excessive gate leakages. To overcome this bottleneck, we extend the natural
+stacking properties of 2D heterostructures to epitaxial fluorite (CaF2), which
+forms a quasi van der Waals interface with 2D semiconductors. We report
+scalable single-layer MoS2 FETs with a crystalline CaF2 insulator of about 2 nm
+thickness, which corresponds to an equivalent oxide thickness of less than 1
+nm. While meeting the stringent requirements of low leakage currents, our
+devices exhibit highly competitive performance and record-small hysteresis. As
+such, our results present a breakthrough for very large scale integration
+towards commercially competitive nano-electronic devices.",1901.10980v1
+2019-02-07,Theoretical insights into the hydrophobicity of low index CeO2 surfaces,"The hydrophobicity of CeO2 surfaces is examined here. Since wettability
+measurements are extremely sensitive to experimental conditions, we propose a
+general approach to obtain contact angles between water and ceria surfaces of
+specified orientations based on density functional calculations. In particular,
+we analysed the low index surfaces of this oxide to establish their
+interactions with water. According to our calculations, the CeO2 (111) surface
+was the most hydrophobic with a contact angle of {\Theta} = 112.53{\deg}
+followed by (100) with {\Theta} = 93.91{\deg}. The CeO2 (110) surface was, on
+the other hand, mildly hydrophilic with {\Theta} = 64.09{\deg}. By combining
+our calculations with an atomistic thermodynamic approach, we found that the O
+terminated (100) surface was unstable unless fully covered by molecularly
+adsorbed water. We also identified a strong attractive interaction between the
+hydrogen atoms in water molecules and surface oxygen, which gives rise to the
+hydrophilic behaviour of (110) surfaces. Interestingly, the adsorption of water
+molecules on the lower-energy (111) surface stabilises oxygen vacancies, which
+are expected to enhance the catalytic activity of this plane. The findings here
+shed light on the origin of the intrinsic wettability of rare earth oxides in
+general and CeO2 surfaces in particular and also explain why CeO2 (100) surface
+properties are so critically dependant on applied synthesis methods.",1902.02662v1
+2019-02-13,Amphoteric behavior of hydrogen (H+1and H-1) in complex hydrides from van der Waals interaction included ab-initio calculation,"In order to identify potential hydrogen storage materials, worldwide
+attention has been focused on hydrides with high gravimetric and volumetric
+capacity. Hydrogen is a unique element that possess positive, negative or
+neutral oxidation state in solids depending upon the chemical environment. If
+one can find hydrogen storage materials where hydrogen is present in both
+negative and positive oxidation state within the same structural framework then
+one can accommodate hydrogen with high volume density. So, it is fundamentally
+as well as technologically important to identify compounds in which hydrogen is
+in amphoteric nature and understand the necessary criteria for its origin. The
+experimental structural analysis of Cyclotriborazane and Diammonium dodeca
+hydro-closo-dodecaborate insinuate the presence of hydrogen with anionic and
+cationic behavior within the same structure. In order to understand the role of
+van der Waals (vdW) interactions on structural parameters, we have considered
+12 different vdW corrected functionals and found that the optPBE-vdW functional
+predicts the equilibrium structural parameters reliably with less than 0.009 %
+accuracy. So, the optPBE-vdW functional is used to calculate charge density,
+electron localization function, total as well as the partial density of state,
+Bader and Born effective charge etc. We have observed that hydrogen is
+exhibiting amphoteric behavior with H closer to B in the negatively charged
+state and that neighboring to N is in a positively charged state.",1902.04748v1
+2019-02-15,Assessing correlations of perovskite catalytic performance with electronic structure descriptors,"Electronic structure descriptors are computationally efficient quantities
+used to construct qualitative correlations for a variety of properties. In
+particular, the oxygen p-band center has been used to guide material discovery
+and fundamental understanding of an array of perovskite compounds for use in
+catalyzing the oxygen reduction and evolution reactions. However, an assessment
+of the effectiveness of the oxygen p-band center at predicting key measures of
+perovskite catalytic activity has not been made, and would be highly beneficial
+to guide future predictions and codify best practices. Here, we have used
+Density Functional Theory at the PBE, PBEsol, PBE+U, SCAN and HSE06 levels to
+assess the correlations of numerous measures of catalytic performance for a
+series of technologically relevant perovskite oxides, using the bulk oxygen
+p-band center as an electronic structure descriptor. We have analyzed
+correlations of the calculated oxygen p-band center for all considered
+functionals with the experimentally measured X-ray emission spectroscopy oxygen
+p-band center and multiple measures of catalytic activity, including high
+temperature oxygen reduction surface exchange rates, aqueous oxygen evolution
+current densities, and binding energies of oxygen evolution intermediate
+species. Our results show that the best correlations for all measures of
+catalytic activity considered here are made with PBE-level calculations, with
+strong observed linear correlations with the bulk oxygen p-band center (R2 =
+0.81-0.87). This study shows that strong linear correlations between numerous
+important measures of catalytic activity and the oxygen p-band bulk descriptor
+can be obtained under a consistent computational framework, and these
+correlations can serve as a guide for future experiments and simulations for
+development of perovskite and related oxide catalysts.",1902.05867v1
+2019-03-04,Rashba spin-splitting in ferroelectric oxides: from rationalizing to engineering,"Ferroelectric Rashba semiconductors (FERSC), in which Rashba spin-splitting
+can be controlled and reversed by an electric field, have recently emerged as a
+new class of functional materials useful for spintronic applications. The
+development of concrete devices based on such materials is, however, still
+hampered by the lack of robust FERSC compounds. Here, we show that the
+coexistence of large spontaneous polarisation and sizeable spin-orbit coupling
+is not sufficient to have strong Rashba effects and clarify why simple
+ferroelectric oxide perovskites with transition metal at the B-site are
+typically not suitable FERSC candidates. By rationalizing how this limitation
+can be by-passed through band engineering of the electronic structure in
+layered perovskites, we identify the Bi$_2$WO$_6$ Aurivillius crystal as the
+first robust ferroelectric with large and reversible Rashba spin-splitting,
+that can even be substantially doped without losing its ferroelectric
+properties. Importantly, we highlight that a unidirectional spin-orbit field
+arises in layered Bi$_2$WO$_6$, resulting in a protection against
+spin-decoherence.We highlight moreover that a unidirectional spin-orbit field
+arises in Bi$_2$WO$_6$, in which the spin-texture is so protected against
+spin-decoherence.",1903.01241v3
+2019-03-05,Polar Coupling Enabled Nonlinear Optical Filtering at MoS$_2$/Ferroelectric Heterointerfaces,"Complex oxide heterointerfaces and van der Waals heterostructures present two
+versatile but intrinsically different platforms for exploring emergent quantum
+phenomena and designing new functionalities. The rich opportunity offered by
+the synergy between these two classes of materials, however, is yet to be
+charted. Here, we report an unconventional nonlinear optical filtering effect
+resulting from the interfacial polar alignment between monolayer MoS$_2$ and a
+neighboring ferroelectric oxide thin film. The second harmonic generation
+response at the heterointerface is either substantially enhanced or almost
+entirely quenched by an underlying ferroelectric domain wall depending on its
+chirality, and can be further tailored by the polar domains. Unlike the
+extensively studied coupling mechanisms driven by charge, spin, and lattice,
+the interfacial tailoring effect is solely mediated by the polar symmetry, as
+well explained via our density functional theory calculations, pointing to a
+new material strategy for the functional design of nanoscale reconfigurable
+optical applications.",1903.01664v2
+2019-03-06,Effective interaction for vanadium oxyhydrides Sr$_{n+1}$V$_n$O$_{2n+1}$H$_n$ ($n=1$ and $n\to\infty$): A constrained-RPA study,"Transition metal oxides have been one of the central objects in the studies
+of electron correlation effects because of their rich variety of physical
+properties mainly depending on the transition metal element. On the other hand,
+exploiting the anion degrees of freedom is less popular but can be another
+promising way to control properties of strongly correlated materials. In
+particular, oxyhydrides offer a unique playground of strongly correlated
+low-dimensional electronic structure, where the $s$ orbitals of hydrogen breaks
+a chemical bond between the cation $t_{2g}$ orbitals. In this study, we
+evaluate the effective interaction, i.e., the screened Coulomb interaction
+parameters in low-energy effective models, for vanadium oxyhydrides
+Sr$_{n+1}$V$_n$O$_{2n+1}$H$_n$ ($n=1,\infty$) using the constrained
+random-phase approximation (cRPA). We find that the effective interaction in
+the $t_{2g}$ model, where only the $t_{2g}$ orbitals are explicitly considered,
+is strongly screened by the $e_g$ bands compared with that for oxides, because
+the $e_g$ bands are much entangled with the $t_{2g}$ bands in the oxyhydrides.
+On the other hand, the effective interaction is rather strong in the $d$ model,
+where all the vanadium $d$ orbitals are explicitly considered, owing to a large
+energy separation between the V-$d$ bands and the anion bands (O-$p$ and
+H-$s$), because the O-$p$ states are stabilized by the existence of the
+hydrogen atoms. These findings suggest that non-trivial and unique correlation
+effects can take place in vanadium oxyhydrides.",1903.02222v2
+2019-03-12,Few layer 2D pnictogens catalyze the alkylation of soft nucleophiles with esters,"Group 15 elements in zero oxidation state (P, As, Sb and Bi), also called
+pnictogens, are rarely used in catalysis due to the difficulties associated in
+preparing well-structured and stable materials. Here, we report on the
+synthesis of highly exfoliated, few layer 2D phosphorene and antimonene in zero
+oxidation state, suspended in an ionic liquid, with the native atoms ready to
+interact with external reagents while avoiding aerobic or aqueous decomposition
+pathways, and on their use as efficient catalysts for the alkylation of
+nucleophiles with esters. The few layer pnictogen material circumvents the
+extremely harsh reaction conditions associated to previous superacid-catalyzed
+alkylations, by enabling an alternative mechanism on surface, protected from
+the water and air by the ionic liquid. These 2D catalysts allow the alkylation
+of a variety of acid-sensitive organic molecules and giving synthetic relevancy
+to the use of simple esters as alkylating agents.",1903.04776v1
+2019-03-20,An increase in membrane cholesterol by graphene oxide disrupts calcium homeostasis in primary astrocytes,"The use of graphene nanomaterials (GNMs) for biomedical applications targeted
+to the central nervous system is exponentially increasing, although precise
+information on their effects on brain cells is lacking. In this work, we
+addressed the molecular changes induced in cortical astrocytes by few-layer
+graphene (FLG) and graphene oxide (GO) flakes. Our results show that exposure
+to FLG/GO does not affect cell viability or proliferation. However, proteomic
+and lipidomic analyses unveiled alterations in several cellular processes,
+including intracellular Ca2+ ([Ca2+]i) homeostasis and cholesterol metabolism,
+which were particularly intense in cells exposed to GO. Indeed, GO exposure
+impaired spontaneous and evoked astrocyte [Ca2+]i signals and induced a marked
+increase in membrane cholesterol levels. Importantly, cholesterol depletion
+fully rescued [Ca2+]i dynamics in GO-treated cells, indicating a causal
+relationship between these GO-mediated effects. Our results indicate that
+exposure to GNMs alters intracellular signaling in astrocytes and may impact on
+astrocyte-neuron interactions.",1903.08447v1
+2018-11-30,Tailoring ink-substrate interactions via thin polymeric layers for high-resolution printing,"The surface properties of a substrate are among the most important parameters
+in the printing technology of functional materials, determining not only the
+printing resolution but also the stability of the printed features. This paper
+addresses the wetting difficulties encountered during inkjet printing on
+homogeneous substrates as a result of improper surface properties. We show that
+the wetting of a substrate and, consequently, the quality of the printed
+pattern, can be mediated through the deposition of polymeric layers that are a
+few nanometers thick. The chemical nature of the polymers determines the
+surface energy and polarity of the thin layer. Some applications, however,
+require a rigorous adjustment of the surface properties. We propose a simple
+and precise method of surface-energy tailoring based on the thermal
+decomposition of poly(methyl methacrylate) (PMMA) layers. A smooth transition
+in the wetting occurs when the thickness of the PMMA layer approaches zero,
+probably due to percolating the underlying surface of the substrate, which
+enables the inkjet printing of complex structures with a high resolution. In
+particular, the wetting of three substrate-ink systems was successfully
+adjusted using the thin polymeric layer: (i) a tantalum-oxide-based ink on
+indium-tin-oxide-coated glass, (ii) a ferroelectric lead zirconate titanate ink
+on a platinized silicon substrate, and (iii) a silver nanoparticle ink on an
+alumina substrate.",1903.10283v1
+2019-01-02,Transport and Phototransport in ITO Nanocrystals with Short to Long-Wave Infrared Absorption,"Nanocrystals are often described as an interesting strategy for the design of
+low-cost optoelectronic devices especially in the infrared range. However the
+driving materials reaching infrared absorption are generally heavy
+metalcontaining (Pb and Hg) with a high toxicity. An alternative strategy to
+achieve infrared transition is the use of doped semiconductors presenting
+intraband or plasmonic transition in the short, mid and long-wave infrared.
+This strategy may offer more flexibility regarding the range of possible
+candidate materials. In particular, significant progresses have been achieved
+for the synthesis of doped oxides and for the control of their doping
+magnitude. Among them, tin doped indium oxide (ITO) is the one providing the
+broadest spectral tunability. Here we test the potential of such ITO
+nanoparticles for photoconduction in the infrared. We demonstrate that In2O3
+nanoparticles presents an intraband absorption in the mid infrared range which
+is transformed into a plasmonic feature as doping is introduced. We have
+determined the cross section associated with the plasmonic transition to be in
+the 1-3x10-13 cm2 range. We have observed that the nanocrystals can be made
+conductive and photoconductive due to a ligand exchange using a short
+carboxylic acid, leading to a dark conduction with n-type character. We bring
+further evidence that the observed photoresponse in the infrared is the result
+of a bolometric effect.",1903.10295v1
+2019-04-03,Possible superconductivity induced by a large spin-orbit coupling in carrier doped iridium oxide insulators: A weak coupling approach,"We study possible superconductivity in a carrier-doped iridium oxide
+insulator Sr$_{2}$IrO$_{4}$ based on an effective $t_{2g}$ three-orbital
+Hubbard model on the square lattice with a large spin-orbit coupling (SOC).
+Numerically solving the linearized Eliashberg equation for the superconducting
+(SC) gap function with the random phase approximation, we systematically
+examine both singlet and triplet SC gap functions with possible pairing
+symmetries and the parameter dependence of the superconductivity. For the
+realistic SOC $\lambda$ and Hund's coupling $J/U$ relevant to
+Sr$_{2}$IrO$_{4}$, namely, for a large $\lambda$ and small $J/U$ region, we
+find that the intra-band antiferromagnetic (AF) pseudospin $\bm{j}_{\text{eff}}
+= -\bm{l}+\bm{s}$ fluctuations favor a $d_{x^{2}-y^{2}}$-wave pseudospin
+$j_{\text{eff}}=1/2$ singlet pairing in the electron-doping. We also find that
+the $d_{x^{2}-y^{2}}$-wave pairing is more stabilized with increasing the SOC
+and decreasing the Hund's coupling. Furthermore, we show for a small $\lambda$
+and large $J/U$ region that an $s_{\pm}$-wave singlet pairing is favored in the
+hole-doped region. The origin of the $s_{\pm}$-wave pairing is due to the
+inter-band pair scattering arising from the intra-orbital AF spin $\bm s$
+fluctuations. Although the possibility of a pseudospin triplet pairing is
+considered, we find it always unfavorable for all parameters studied here. The
+experimental consequences for other strongly correlated materials with a large
+SOC are also discussed.",1904.01812v1
+2019-04-14,Tuning the metal-insulator transition in epitaxial SrVO3 films by uniaxial strain,"Understanding of the metal-insulator transition (MIT) in correlated
+transition-metal oxides is a fascinating topic in condensed matter physics and
+a precise control of such transitions plays a key role in developing novel
+electronic devices. Here we report an effective tuning of the MIT in epitaxial
+SrVO3 (SVO) films by expanding the out-of-plane lattice constant without
+changing in-plane lattice parameters, through helium ion irradiation. Upon
+increase of the ion fluence, we observe a MIT with a crossover from metallic to
+insulating state in SVO films. A combination of transport and magnetoresistance
+measurements in SVO at low temperatures reveals that the observed MIT is mainly
+ascribed to electron-electron interactions rather than disorder-induced
+localization. Moreover, these results are well supported by the combination of
+density functional theory and dynamical mean field theory (DFT+DMFT)
+calculations, further confirming the decrease of the bandwidth and the enhanced
+electron-electron interactions resulting from the expansion of out-of-plane
+lattice constant. These findings provide new insights into the understanding of
+MIT in correlated oxides and perspectives for the design of unexpected
+functional devices based on strongly correlated electrons.",1904.06629v1
+2019-08-08,Electric selective activation of memristive interfaces in TaO$_x$-based devices,"The development of novel devices for neuromorphic computing and
+non-traditional logic operations largely relies on the fabrication of well
+controlled memristive systems with functionalities beyond standard bipolar
+behavior and digital ON-OFF states. In the present work we demonstrate for
+Ta$_2$O$_5$-based devices that it is possible to selectively
+activate/deactivate two series memristive interfaces in order to obtain
+clockwise or counter-clockwise multilevel squared remanent resistance loops,
+just by controlling the (a)symmetry of the applied stimuli and independently of
+the nature of the used metallic electrodes. Based on our thorough
+characterization, analysis and modeling, we show that the physical origin of
+this electrical behavior relies on controlled oxygen vacancies electromigration
+between three different zones of the active Ta$_2$O$_{5-x}$ layer: a central --
+bulk -- one and two quasi-symmetric interfaces with reduced TaO$_{2-h(y)}$
+layers. Our devices fabrication process is rather simple as it implies the room
+temperature deposition of only one CMOS compatible oxide -- Ta-oxide -- and one
+metal, suggesting that it might be possible to take advantage of these
+properties at low cost and with easy scability. The tunable opposite remanent
+resistance loops circulations with multiple -- analogic -- intermediate stable
+states allows mimicking the adaptable synaptic weight of biological systems and
+presents potential for non-standard logic devices.",1908.03056v1
+2019-08-19,Exploring the role of electronic structure on photo-catalytic behavior of carbon-nitride polymorphs,"A fully self-consistent density-functional theory (DFT) with improved
+functionals is used to provide a comprehensive account of structural,
+electronic, and optical properties of C$_{3}$N$_{4}$ polymorphs. Using our
+recently developed van Leeuwen-Baerends (vLB) corrected local-density
+approximation (LDA), we implemented LDA+vLB within full-potential
+N$^{th}$-order muffin-tin orbital (FP-NMTO) method and show that it improves
+structural properties and band gaps compared to semi-local functionals
+(LDA/GGA). We demonstrate that the LDA+vLB predicts band-structure and
+work-function for well-studied 2D-graphene and bulk-Si in very good agreement
+with experiments, and more exact hybrid functional (HSE) calculations as
+implemented in the Quantum-Espresso (QE) package. The structural and
+electronic-structure (band gap) properties of C$_{3}$N$_{4}$ polymorphs
+calculated using FP-NMTO-LDA+vLB is compared with more sophisticated
+hybrid-functional calculations. We also perform detailed investigation of
+photocatalytic behavior using QE-HSE method of C$_{3}$N$_{4}$ polymorphs
+through work-function, band (valence and conduction) position with respect to
+water reduction and oxidation potential. Our results show
+$\gamma$-C$_{3}$N$_{4}$ as the best candidate for photocatalysis among all the
+C$_{3}$N$_{4}$~polymorphs but it is dynamically unstable at `zero' pressure. We
+show that $\gamma$-C$_{3}$N$_{4}$ can be stabilized under hydrostatic-pressure,
+which improves its photocatalytic behavior relative to water reduction and
+oxidation potentials.",1908.06596v2
+2019-08-22,High-throughput fabrication and semi-automated characterization of oxide thin film transistors,"High throughput experimental methods are known to accelerate the rate of
+research, development, and deployment of electronic materials. For example,
+thin films with lateral gradients in composition, thickness, or other
+parameters have been used alongside spatially-resolved characterization to
+assess how various physical factors affect material properties under varying
+measurement conditions. Similarly, multi-layer electronic devices that contain
+such graded thin films as one or more of their layers can also be characterized
+spatially in order to optimize the performance. In this work, we apply these
+high throughput experimental methods to thin film transistors (TFTs),
+demonstrating combinatorial device fabrication and semi-automated
+characterization using sputtered Indium-Gallium-Zinc-Oxide (IGZO) TFTs as a
+case study. We show that both extrinsic and intrinsic types of device gradients
+can be generated in a TFT library, such as channel thickness and length,
+channel cation compositions, and oxygen atmosphere during deposition. We also
+present a semi-automated method to measure the 44 devices fabricated on a
+50x50mm substrate that can help to identify properly functioning TFTs in the
+library and finish the measurement in a short time. Finally, we propose a fully
+automated characterization system for similar TFT libraries, which can be
+coupled with high throughput data analysis. These results demonstrate that high
+throughput methods can accelerate the investigation of TFTs and other
+electronic devices.",1908.08287v1
+2019-11-09,Pulsed laser deposition of single phase n- and p-type Cu2O thin films with low resistivity,"Low resistivity (~3-24 mOhm.cm) with tunable n- and p-type phase pure Cu2O
+thin films have been grown by pulsed laser deposition at 25-200 0C by varying
+the background oxygen partial pressure (O2pp). Capacitance data obtained by
+electrochemical impedance spectroscopy was used to determine the conductivity
+(n- or p-type), carrier density, and flat band potentials for samples grown on
+indium tin oxide (ITO) at 25 0C. The Hall mobility of the n- and p-type Cu2O
+was estimated to be ~ 0.85 cm2.V-1s-1 and ~ 4.78 cm2.V-1s-1 respectively for
+samples grown on quartz substrate at 25 0C. An elevated substrate temperature ~
+200 0C with O2pp = 2 - 3 mTorr yielded p-type Cu2O films with six orders of
+magnitude higher resistivities in the range ~ 9 - 49 kOhm.cm and mobilities in
+the range ~ 13.5 - 22.2 cm2.V-1s-1. UV-Vis-NIR diffuse reflectance spectroscopy
+showed optical bandgaps of Cu2O films in the range of 1.76 to 2.15 eV depending
+on O2pp. Thin films grown at oxygen-rich conditions O2pp > 7 mTorr yielded
+mixed-phase copper oxide irrespective of the substrate temperatures and upon
+air annealing at 550 0C for 1 hour completely converted to CuO phase with
+n-type semiconducting properties (~12 Ohm.cm, ~1.50 cm2.V-1s-1). The as-grown
+p- and n-type Cu2O showed rectification and a photovoltaic (PV) response in
+solid junctions with n-ZnO and p-Si electrodes respectively. Our findings may
+create new opportunities for devising Cu2O based junctions requiring low
+process temperatures.",1911.03727v2
+2019-11-17,Interfacial-Redox-Induced Tuning of Superconductivity in YBa$_{2}$Cu$_{3}$O$_{7-δ}$,"Solid state ionic approaches for modifying ion distributions in getter/oxide
+heterostructures offer exciting potentials to control material properties. Here
+we report a simple, scalable approach allowing for total control of the
+superconducting transition in optimally doped YBa$_{2}$Cu$_{3}$O$_{7-{\delta}}$
+(YBCO) films via a chemically-driven ionic migration mechanism. Using a thin Gd
+capping layer of up to 20 nm deposited onto 100 nm thick epitaxial YBCO films,
+oxygen is found to leach from deep within the YBCO. Progressive reduction of
+the superconducting transition is observed, with complete suppression possible
+for a sufficiently thick Gd layer. These effects arise from the combined impact
+of redox-driven electron doping and modification of the YBCO microstructure due
+to oxygen migration and depletion. This work demonstrates an effective ionic
+control of superconductivity in oxides, an interface induced effect that goes
+well into the quasi-bulk regime, opening up possibilities for electric field
+manipulation.",1911.07275v1
+2019-12-04,X-rays induced atomic dynamics in a lithium-borate glass,"The continuous development of synchrotron-based experimental techniques in
+the X-ray range provides new possibilities to probe the structure and the
+dynamics of bulk materials down to inter-atomic distances. However, the
+interaction of intense X-ray beams with matter can also induce changes in the
+structure and dynamics of materials. A reversible and non-destructive beam
+induced dynamics has recently been observed in X-ray photon correlation
+spectroscopy experiments in some oxide glasses at sufficiently low absorbed
+doses, and is here investigated in a (Li$_2$O)$_{0.5}$(B$_2$O$_3$)$_{0.5}$
+glass. The characteristic time of this induced dynamics is inversely
+proportional to the intensity of the X-ray beam, with a coefficient that
+depends on the chemical composition and local structure of the probed glass,
+making it a potentially new tool to investigate fundamental properties of a
+large class of disordered systems. While the exact mechanisms behind this
+phenomenon are yet to be elucidated, we report here on the measurement of the
+exchanged wave-vector (and thus length-scale) dependence of the characteristic
+time of this induced dynamics, and show that it follows the same power-law
+observed in vitreous silica. This supports the idea that a unique explanation
+for this effect in different oxide glasses should be looked for.",1912.01943v1
+2019-12-05,Effect of Proton Irradiation Temperature on Zinc Oxide Metal-Semiconductor-Metal Ultraviolet Photodetectors,"The electrical and structural characteristics of 50 nm zinc oxide (ZnO)
+metal-semiconductor-metal (MSM) ultraviolet (UV) photodetectors subjected to
+proton irradiation at different temperatures are reported and compared. We
+irradiated the devices with 200 keV protons to a fluence of 1016 cm-2.
+Examination of the X-ray diffraction (XRD) rocking curves indicates a strongly
+preferred (100) orientation for the grains of the as-deposited film, with
+decreases in crystal quality for all irradiated samples. In addition, peak
+shifts in XRD and Raman spectra of the control sample relative to well-known
+theoretical positions are indicative of tensile strain in the as-deposited ZnO
+films. We observed shifts of these peaks towards theoretical unstrained
+positions in the irradiated films relative to the as-deposited film indicate
+partial relaxation of this strain. Raman spectra also indicate increases of
+oxygen vacancies (V_O ) and zinc interstitials (Zn_i ) relative to the control
+sample. Additionally, photocurrent versus time measurements showed up to 2x
+increases in time constants for samples irradiated at lower temperatures months
+after irradiation, indicating that the defects introduced by suppression of
+thermally-activated dynamic annealing process has a long-term deleterious
+effect on device performance.",1912.02321v1
+2019-12-09,Biochemically altered human erythrocytes as a carrier for targeted delivery of primaquine: an in vitro study,"The aim of this study was to investigate human erythrocytes as a carrier for
+targeted drug delivery of primaquine (PQ). The process of PQ loading in human
+erythrocytes, as well as the effect of PQ loading on the oxidative status of
+erythrocytes, was also studied. At PQ concentrations of 2, 4, 6, and 8 mg/mL
+and an incubation time of 2 h, the ratios of the concentrations of PQ entrapped
+in erythrocytes to that in the incubation medium were 0.515, 0.688, 0.697 and
+0.788, respectively. The maximal decline of erythrocyte reduced glutathione
+content was observed at 8 mg/mL of PQ compared with native erythrocytes p <
+0.001. In contrast, malondialdehyde and protein carbonyl were significantly
+increased in cells loaded with PQ (p < 0.001). Furthermore, osmotic fragility
+of PQ carrier erythrocytes was increased in comparison with unloaded cells.
+Electron microscopy revealed spherocyte formation with PQ carrier erythrocytes.
+PQ-loaded cells showed sustained drug release over a 48 h period. Erythrocytes
+were loaded with PQ successfully, but there were some biochemical as well as
+physiological changes that resulted from the effect of PQ on the oxidative
+status of drug-loaded erythrocytes. These changes may result in favorable
+targeting of PQ-loaded cells to reticulo-endothelial organs. The relative
+impact of these changes remains to be explored in ongoing animal studies.",1912.04359v1
+2019-12-10,A first-principles investigation of the structural and electrochemical properties of biredox ionic species in acetonitrile,"Biredox ionic liquids are a new class of functionalized electrolytes that may
+play an important role in future capacitive energy storage devices. By allowing
+additional storage of electrons inside the liquids, they can improve device
+performance significantly. However current devices employ nanoporous carbons in
+which the diffusion of the liquid and the adsorption of the ions could be
+affected by the occurrence of electron-transfer reactions. It is therefore
+necessary to understand better the thermodynamics and the kinetics of such
+reactions in biredox ionic liquids. Here we perform ab initio molecular
+dynamics simulations of both the oxidized and reduced species of several
+redox-active ionic molecules (used in biredox ionic liquids) dissolved in
+acetonitrile solvent and compare them with the bare redox molecules. We show
+that in all the cases, it is necessary to introduce a two Gaussian state model
+to calculate the reaction free energies accurately. These reaction free
+energies are only slightly affected by the presence of the IL group on the
+molecule. We characterize the structure of the solvation shell around the redox
+active part of the molecules and show that in the case of TEMPO-based molecules
+strong reorientation effects occur during the oxidation reaction.",1912.04879v1
+2019-12-11,Molybdenum Trioxide Gates for Suppression of Leakage Current in InAlN/GaN HEMTs at 300°C,"Because high electron mobility transistors (HEMTs) often exhibit significant
+gate leakage during high-temperature operation, the choice of Schottky metal is
+critical. Increased gate leakage and reduced ON/OFF ratio are unsuitable for
+the design of high-temperature electronics and integrated circuits. This paper
+presents high-temperature characteristics of depletion-mode molybdenum trioxide
+(MoO${_3}$)-gated InAlN/GaN-on-silicon HEMTs in air. After a room temperature
+oxidation of the Mo for 10 weeks, the leakage of the HEMT is reduced over 60
+times compared to the as-deposited Mo. The use of MoO${_3}$ as the Schottky
+gate material enables low gate leakage, resulting in a high ON/OFF current
+ratio of 1.2 x 10${^8}$ at 25{\deg}C and 1.2 x 10${^5}$ at 300{\deg}C in air.
+At 400{\deg}C, gate control of the InAlN/GaN two-dimensional electron gas
+(2DEG) channel is lost and unrecoverable. Here, this permanent device failure
+is attributed to volatilization of the MoO${_3}$ gate due to the presence of
+water vapor in air. Passivation of the device with SiN enables operation up to
+500{\deg}C, but also increases the leakage current. The suppression of gate
+leakage via Mo oxidation and resulting high ON/OFF ratio paves the way for
+viable high-temperature GaN-based electronics that can function beyond the
+thermal limit of silicon once proper passivation is achieved.",1912.05667v1
+2019-12-13,Artifcial-intelligence-driven discovery of catalyst \textit{genes} with application to CO2 activation on semiconductor oxides,"Catalytic-materials design requires predictive modeling of the interaction
+between catalyst and reactants. This is challenging due to the complexity and
+diversity of structure-property relationships across the chemical space. Here,
+we report a strategy for a rational design of catalytic materials using the
+artifcial intelligence approach (AI) subgroup discovery. We identify catalyst
+\textit{genes} (features) that correlate with mechanisms that trigger,
+facilitate, or hinder the activation of carbon dioxide (CO$_2$) towards a
+chemical conversion. The AI model is trained on frst-principles data for a
+broad family of oxides. We demonstrate that surfaces of experimentally
+identifed good catalysts consistently exhibit combinations of \textit{genes}
+resulting in a strong elongation of a C-O bond. The same combinations of
+\textit{genes} also minimize the OCO-angle, the previously proposed indicator
+of activation, albeit under the constraint that the Sabatier principle is
+satisfed. Based on these fndings, we propose a set of new promising catalyst
+materials for CO$_2$ conversion.",1912.06515v3
+2019-12-19,Prospects for laser cooling of polyatomic molecules with increasing complexity,"Optical cycling transitions and direct laser cooling have recently been
+demonstrated for a number of alkaline-earth dimers and trimer molecules. This
+is made possible by diagonal Franck-Condon factors between the vibrational
+modes of the optical transition. Achieving a similar degree of cooling to
+micro-Kelvin equivalent kinetic energy for larger polyatomic molecules,
+however, remains challenging. Since polyatomic molecules are characterized by
+multiple degrees of freedom and have a correspondingly more complex structure,
+it is far from obvious whether there exist polyatomic molecules that can
+repeatedly scatter photons. Here, we propose chemical substitution approaches
+to engineer large polyatomic molecules with optical cycling centers (OCCs)
+containing alkaline-earth oxide dimers or acetylenic alkaline-earth trimers
+(i.e. M--C$\equiv$C) connected to CH$_n$ chains or fullerenes. To validate the
+OCC-character of the selected molecules we performed electronic structure
+calculations of the equilibrium configuration of both ground and excited
+potential energy surfaces, evaluated their vibrational and bending modes, and
+corresponding Franck-Condon factors for all but the most complex molecules. For
+fullerenes, we have shown that OCCs based on M--C$\equiv$C can perform better
+than those based on alkaline-earth oxide dimers.
+  In addition, for heavier polyatomic molecules it might be advantageous to
+attach two OCCs, thereby potentially doubling the photon scattering rate and
+thus speeding up cooling rates.",1912.09364v3
+2019-12-27,Attosecond time-domain measurement of core-excitonic decay in magnesium oxide,"Excitation of ionic solids with extreme ultraviolet pulses creates localized
+core-excitons, which in some cases couple strongly to the lattice. Here,
+core-excitonic states of magnesium oxide are studied in the time domain at the
+Mg $\text{L}_{2,3}$ edge with attosecond transient reflectivity spectroscopy.
+Attosecond pulses trigger the excitation of these short-lived quasiparticles,
+whose decay is perturbed by time-delayed near infrared optical pulses. Combined
+with a few-state theoretical model, this reveals that the optical pulse shifts
+the energy of bright core-exciton states as well as induces features arising
+from dark core-excitons. We report coherence lifetimes for the first two
+core-excitons of $2.3 \pm 0.2$ and $1.6 \pm 0.5$ femtoseconds and show that
+these short lifetimes are primarily a consequence of strong exciton-phonon
+coupling, disclosing the drastic influence of structural effects in this
+ultrafast relaxation process.",1912.12266v1
+2019-12-29,Strain-Driven Disproportionation at a Correlated Oxide Metal-Insulator Transition,"Metal-to-insulator phase transitions in complex oxide thin films are exciting
+phenomena which may be useful for device applications, but in many cases the
+physical mechanism responsible for the transition is not fully understood. Here
+we demonstrate that epitaxial strain generates local disproportionation of the
+NiO6 octahedra, driven through changes in the oxygen stoichiometry, and that
+this directly modifies the metal-to-insulator phase transition in epitaxial
+(001) NdNiO3 thin films. Theoretically, we predict that the Ni-O-Ni bond angle
+decreases, while octahedral tilt and local disproportionation of the NiO6
+octahedra increases resulting in a small band gap in otherwise metallic system.
+This is driven by an increase in oxygen vacancy concentration in the rare-earth
+nickelates with increasing in-plane biaxial tensile strain. Experimentally, we
+find an increase in pseudocubic unit-cell volume and resistivity with
+increasing biaxial tensile strain, corroborating our theoretical predictions.
+With electron energy loss spectroscopy and x-ray absorption, we find a
+reduction of the Ni valence with increasing tensile strain. These results
+indicate that epitaxial strain modifies the oxygen stoichiometry of rare-earth
+perovskite thin films and through this mechanism affect the metal-to-insulator
+phase transition in these compounds.",1912.12710v1
+2019-12-31,Production of nitric oxide by a fragmenting bolide: An exploratory numerical study,"A meteoroid's hypersonic passage through the Earth's atmosphere results in
+ablational and fragmentational mass loss. Potential shock waves associated with
+a parent object as well as its fragments can modify the surrounding atmosphere
+and produce a range of physico-chemical effects. Some of the thermally driven
+chemical and physical processes induced by meteoroid-fragment generated shock
+waves, such as nitric oxide (NO) production, are less understood. Any estimates
+of meteoric NO production depend not only on a quantifiable meteoroid
+population and a rate of fragmentation, with a size capable of producing high
+temperature flows, but also on understanding the physical properties of the
+meteor flows along with their thermal history. We performed an exploratory
+pilot numerical study using ANSYS Fluent, the CFD code, to investigate the
+production of NO in the upper atmosphere by small meteoroids (or fragments of
+meteoroids after they undergo a disruption episode) in the size range from 1 cm
+m to 1 m. Our model uses the simulation of a spherical body in the continuum
+flow at 70 and 80 km altitude to approximate the behaviour of a small meteoroid
+capable of producing NO. The results presented in this exploratory study are in
+good agreement with previous studies.",1912.13130v2
+2020-03-02,"Electrodynamics of Conductive Oxides: Intensity-dependent anisotropy, reconstruction of the effective dielectric constant, and harmonic generation","We study electromagnetic pulse propagation in an indium tin oxide nanolayer
+in the linear and nonlinear regimes. We use the constitutive relations to
+reconstruct the effective dielectric constant of the medium, and show that
+nonlocal effects induce additional absorption resonances and anisotropic
+dielectric response: longitudinal and transverse effective dielectric functions
+are modulated differently along the propagation direction, and display
+different epsilon-near-zero crossing points with a discrepancy that increases
+with increasing intensity. We predict that hot carriers induce a dynamic
+redshift of the plasma frequency and a corresponding translation of the
+effective nonlinear dispersion curves that can be used to predict and quantify
+nonlinear refractive index changes as a function of incident laser peak power
+density. Our results suggest that large, nonlinear refractive index changes can
+occur without the need for epsilon-near-zero modes to couple with plasmonic
+resonators. At sufficiently large laser pulse intensities, we predict the onset
+of optical bistability, while the presence of additional pump absorption
+resonances that arise from longitudinal oscillations of the free electron gas
+give way to corresponding resonances in the second and third harmonic spectra.
+A realistic propagation model is key to unraveling the basic physical
+mechanisms that play a fundamental role in the dynamics.",2003.01059v1
+2020-03-24,Characteristic Lengths of Interlayer Charge-Transfer in Correlated Oxide Heterostructures,"Using interlayer interaction to control functional heterostructures with
+atomic-scale designs has become one of the most effective interface-engineering
+strategies nowadays. Here, we demonstrate the effect of a crystalline LaFeO3
+buffer layer on amorphous and crystalline LaAlO3/SrTiO3 heterostructures. The
+LaFeO3 buffer layer acts as an energetically favored electron acceptor in both
+LaAlO3/SrTiO3 systems, resulting in modulation of interfacial carrier density
+and hence metal-to-insulator transition. For amorphous and crystalline
+LaAlO3/SrTiO3 heterostructures, the metal-to-insulator transition is found when
+the LaFeO3 layer thickness crosses 3 and 6 unit cells, respectively. Such
+different critical LaFeO3 thicknesses are explained in terms of distinct
+characteristic lengths of the redox-reaction-mediated and
+polar-catastrophe-dominated charge transfer, controlled by the interfacial
+atomic contact and Thomas-Fermi screening effect, respectively. Our results not
+only shed light on the complex interlayer charge transfer across oxide
+heterostructures but also provides a new route to precisely tailor the
+charge-transfer process at a functional interface.",2003.10677v1
+2020-03-29,Domain evolution in bended freestanding BaTiO3 ultrathin films: a phase-field simulation,"Perovskite ferroelectric oxides are usually considered to be brittle
+materials, however, recent work [Dong et al., Science 366, 475 (2019)]
+demonstrated the super-elasticity in the freestanding BaTiO3 thin films. This
+property may originate from the ferroelectric domain evolution during the
+bending, which is difficult to observe in experiments. Therefore, understanding
+the relation among the bending deformation, thickness of the films, and the
+domain dynamics is critical for their potential applications in flexible
+ferroelectric devices. Here, we reported the dynamics of ferroelectric
+polarization in the freestanding BaTiO3 ultrathin films in the presence of
+large bending deformation up to 40{\deg} using phase-field simulation. The
+ferroelectric domain evolution reveals the transition from the flux-closure to
+a/c domains with ""vortex-like"" structures, which caused by the increase of
+out-of-plane ferroelectric polarization. Additionally, by varying the film
+thickness in the identical bending situation, we found the a/c phase with
+""vortex-like"" structure emerges only as the film thickness reached 12 nm or
+higher. Results from our investigations provide instructive information for the
+microstructure evolution of bending ferroelectric perovskite oxide films, which
+could serve as guide for the future application of ferroelectric films on
+flexible electronic devices.",2003.13020v1
+2020-03-30,Vibrational coherent control of localized d-d electronic excitation,"Addressing the role of quantum coherence in the interplay between the
+different matter constituents (electrons, phonons and spin) is a critical step
+towards understanding transition metal oxides and design complex materials with
+new functionalities. Here we use coherent vibrational control of onsite d-d
+electronic transitions in a model edge-sharing insulating transition metal
+oxide (CuGeO3) to single-out the effects of vibrational coherence in
+electron-phonon coupling. By comparing time domain experiments based on high
+and low frequency ultrashort pumps with a fully quantum description of phonon
+assisted absorption, we could distinguish the processes associated to
+incoherent thermal lattice fluctuations from those driven by the coherent
+motion of the atoms. In particular, while thermal fluctuation of the phonon
+bath uniformly increases the electronic absorption, the resonant excitation of
+phonon modes results also in light-induced transparency which is coherently
+controlled by the vibrational motion.",2003.13447v2
+2020-04-14,Enhanced Solar Water Splitting by Swift Charge Separation in Au/FeOOH Sandwiched Single Crystalline Fe$_2$O$_3$ Nanoflake Photoelectrodes,"In this work, single crystalline $\alpha$-Fe$_2$O$_3$ nanoflakes (NFs) are
+formed in a highly dense array by Au seeding of a Fe substrate by a thermal
+oxidation technique. The NFs are conformally decorated with a thin FeOOH
+cocatalyst layer. Photoelectrochemical (PEC) measurements show that this
+photoanode with the $\alpha$-Fe$_2$O$_3$/FeOOH NFs rooted on the Au/Fe
+structure exhibits a significantly enhanced PEC water oxidation performance
+compared to the plain $\alpha$-Fe$_2$O$_3$ nanostructure on the Fe substrate.
+The $\alpha$-Fe$_2$O$_3$/FeOOH NFs on Au/Fe photoanode yields a photocurrent
+density of 3.1 mA cm-2 at 1.5 VRHE, and a remarkably low onset potential of
+0.5-0.6 VRHE in 1 M KOH under AM 1.5G (100 mW cm-2) simulated sunlight
+illumination. The enhancement in PEC performance can be attributed to a
+synergistic effect of the FeOOH top decoration and Au under-layer. While FeOOH
+facilitates hole transfer at the interface of electrode/electrolyte, the Au
+layer provides a sink for the electron transport to the back contact: this
+leads overall to a drastically improved charge-separation efficiency in the
+single crystalline $\alpha$-Fe$_2$O$_3$ NF photoanode.",2005.01604v1
+2020-05-06,Oxidation of the Interiors of Carbide Exoplanets,"Astrophysical measurements have shown that some stars have sufficiently high
+carbon-to-oxygen ratios such that the planets they host would be mainly
+composed of carbides instead of silicates. We studied the behavior of silicon
+carbide in the presence of water under the high pressure-temperature conditions
+relevant to planetary interiors in the laser-heated diamond-anvil cell (LHDAC).
+When reacting with water, silicon carbide converts to silica (stishovite) and
+diamond at pressures up to 50 GPa and temperatures up to 2500 K: SiC + 2H$_2$O
+-> SiO$_2$ + C + 2H$_2$. Therefore, if water can be incorporated into carbide
+planets during their formation or through later delivery, they could be
+oxidized and have mineralogy dominated by silicates and diamond in their
+interiors. The reaction could produce CH$_4$ at shallower depths and H$_2$ at
+greater depths which could be degassed from the interior, causing the
+atmospheres of the converted carbon planets to be rich in reducing gases.
+Excess water after the reaction can be stored in dense silica polymorphs in the
+interiors of the converted carbon planets. Such conversion of mineralogy to
+diamond and silicates would decrease the density of carbon-rich planet, making
+the converted planets distinct from silicate planets in mass-radius relations
+for the 2-8 Earth mass range.",2005.03175v4
+2020-05-22,Temperature dependence of the optical properties of silicon nanocrystals,"Silicon nanocrystals (SiNCs) have been under active investigation in the last
+decades and have been considered as a promising candidate for many
+optoelectronic applications including highly-efficient solar cells. Some of the
+fundamental properties of interest in these nanostructures is the temperature
+dependence of their optical absorption onset, and how this is controlled by
+different passivation regimes. In the present work we employ first-principles
+calculations in conjunction with the special displacement method to study the
+temperature dependence of the band gap renormalization of free-standing
+hydrogen-terminated, and oxidized SiNCs, as well as matrix-embedded SiNCs in
+amorphous silica, and we obtain good agreement with experimental
+photoluminescence data. We also provide strong evidence that the
+electron-phonon interplay at the surface of the nanocrystal is suppressed by
+oxidation and the surrounding amorphous matrix. For the matrix-embedded SiNCs,
+we show a high correlation between the temperature dependence of the band gap
+and the Si-Si strained bonds. This result emphasizes the immanent relationship
+of electron-phonon coupling and thermal structural distortions. We also
+demonstrate that, apart from quantum confinement, Si- Si strained bonds are the
+major cause of zero-phonon quasidirect transitions in matrix-embedded SiNCs. As
+a final point, we clarify that, unlike optical absorption in bulk Si,
+phonon-assisted electronic transitions play a secondary role in SiNCs.",2005.11174v1
+2020-05-24,Applying configurational complexity to the 2D Ruddlesden-Popper crystal structure,"The 2D layered Ruddlesden-Popper crystal structure can host a broad range of
+functionally important behaviors. Here we establish extraordinary
+configurational disorder in a two dimensional layered Ruddlesden-Popper (RP)
+structure using entropy stabilization assisted synthesis. A protype A2CuO4 RP
+cuprate oxide with five components (La, Pr, Nd, Sm, Eu) on the A-site
+sublattice is designed and fabricated into epitaxial single crystal films using
+pulsed laser deposition. By comparing (La0.2Pr0.2Nd0.2Sm0.2Eu0.2)2CuO4 crystals
+grown under identical conditions but different substrates, it is found that
+heteroepitaxial strain plays an important role in crystal phase formation. When
+grown on a near lattice matched substrate, the high entropy oxide film features
+a T'-type RP structure with uniform A-site cation mixing and square-planar CuO4
+units, however, growing under strong compressive strain results in a single
+crystal non-RP cubic phase consistent with a CuX2O4 spinel structure. These
+observations are made with a range of combined characterizations using X-ray
+diffraction, atomic-resolution scanning transmission electron microscopy,
+energy-dispersive X-ray spectroscopy, and X-ray absorption spectroscopy
+measurements. Designing configurational complexity and moving between 2D
+layered RP and 3D cubic crystal structures in this class of cuprate materials
+opens many opportunities for new design strategies related to
+magnetoresistance, unconventional superconductivity, ferroelectricity,
+catalysis, and ion transport.",2005.11801v1
+2020-06-03,Making Graphene Nano Inductor Using Table Top Laser Engraver,"There is great interest in so-called nano-electronic devices due to the
+furious rate of device miniaturization. Fabrication of micro and nano scale
+resistors and capacitors have already been achieved steadily, but so far, there
+has been little development in the way of nano-scale coil inductors. This is
+because of the physical limitations in miniaturization of the design of a
+solenoid with wires coiled around a metallic core. So, while transistors get
+steadily smaller, basic inductors in electronics remained relatively bulky. Few
+methods exist for creating conductive polymer coils and graphene-based kinetic
+nano-inductors, but their large-scale fabrication process is complex and mostly
+beyond the current commercial technology available. So, a simpler, scalable,
+and robust fabrication technique is needed to overcome this bottleneck. In this
+work we demonstrate a new technique consisting of the laser lithography using a
+laser engraver of a (poly)vinyl alcohol (PVA)/graphene oxide film composite
+which results in a large inductive effect. We attribute this behavior to the
+formation of high curvature twisted screw dislocation type conductive pathways
+composed of polyacetylene chains linked by pi-pi interactions to reduced
+graphene oxide flakes resulting in inductive effect.",2006.02331v1
+2020-06-09,The effect of varying atmospheric pressure upon habitability and biosignatures of Earth-like planets,"Understanding the possible climatic conditions on rocky extrasolar planets,
+and thereby their potential habitability, is one of the major subjects of
+exoplanet research. Determining how the climate, as well as potential
+atmospheric biosignatures, change under different conditions is a key aspect
+when studying Earth-like exoplanets. One important property is the atmospheric
+mass hence pressure and its influence on the climatic conditions. Therefore,
+the aim of the present study is to understand the influence of atmospheric mass
+on climate, hence habitability, and the spectral appearance of planets with
+Earth-like, that is, N2-O2 dominated, atmospheres orbiting the Sun at 1
+Astronomical Unit. This work utilizes a 1D coupled, cloud-free,
+climate-photochemical atmospheric column model; varies atmospheric surface
+pressure from 0.5 bar to 30 bar; and investigates temperature and key species
+profiles, as well as emission and brightness temperature spectra in a range
+between 2{\mu}m - 20{\mu}m. Increasing the surface pressure up to 4 bar leads
+to an increase in the surface temperature due to increased greenhouse warming.
+Above this point, Rayleigh scattering dominates and the surface temperature
+decreases, reaching surface temperatures below 273K (approximately at ~34 bar
+surface pressure). For ozone, nitrous oxide, water, methane, and carbon
+dioxide, the spectral response either increases with surface temperature or
+pressure depending on the species. Masking effects occur, for example, for the
+bands of the biosignatures ozone and nitrous oxide by carbon dioxide, which
+could be visible in low carbon dioxide atmospheres.",2006.05207v1
+2020-06-19,Regular-Triangle Trimer and Charge Order Preserving the Anderson Condition in the Pyrochlore Structure of CsW$_2$O$_6$,"Since the discovery of the Verwey transition in magnetite, transition metal
+compounds with pyrochlore structures have been intensively studied as a
+platform for realizing remarkable electronic phase transitions. We report the
+discovery of a unique phase transition that preserves the cubic symmetry of the
+beta-pyrochlore oxide CsW$_2$O$_6$, where each of W 5d electrons are confined
+in regular-triangle W3 trimers. This trimer formation is an unprecedented
+self-organization of d electrons, which can be resolved into a charge order
+satisfying the Anderson condition in a nontrivial way, orbital order caused by
+the distortion of WO6 octahedra, and the formation of a spin-singlet pair in a
+regular-triangle trimer. Electronic instability due to the unusual
+three-dimensional nesting of Fermi surfaces and the localized nature of the 5d
+electrons characteristic of the pyrochlore oxides were found to play important
+roles in this unique charge-orbital-spin coupled phenomenon.",2006.11053v1
+2020-06-23,Proton polarons in HxWO3 by synchrotron photoemission and DFT modelling,"The measurement of hydrogen induced changes on the electronic structure of
+transition metal oxides by X-ray photoelectron spectroscopy is a challenging
+endeavor, since the origin of the photoelectron cannot be unambiguously
+assigned to hydrogen. The H-induced electronic structure changes in tungsten
+trioxide have been known for more than 100 years, but are still being
+controversially debated. The controversy stems from the difficulty in
+disentangling effects due to hydrogenation from the effects of oxygen
+deficiencies. Using a membrane approach to X-ray photoelectron spectroscopy, in
+combination with tuneable synchrotron radiation we measure simultaneously core
+levels and valence band up to a hydrogen pressure of 1000 mbar. Upon
+hydrogenation, the intensities of the W$^{5+}$ core level and a state close to
+the Fermi level increase following the pressure-composition isotherm curve of
+bulk H$_x$WO$_3$. Combining experimental data and density-functional theory the
+description of the hydrogen induced coloration by a proton polaron model is
+corroborated. Although hydrogen is the origin of the electronic structure
+changes near the Fermi edge, the valence band edge is now dominated by tungsten
+orbitals instead of oxygen as is the case for the pristine oxide having wider
+implication for its use as (photo-electrochemical) catalyst.",2006.13113v2
+2020-06-23,Oxide Fermi liquid universality revealed by electron spectroscopy,"We present a combined soft x-ray and high-resolution vacuum-ultraviolet
+angle-resolved photoemission spectroscopy study of the electron-overdoped
+cuprate Pr$_{1.3-x}$La$_{0.7}$Ce$_{x}$CuO$_4$ (PLCCO). Demonstration of its
+highly two-dimensional band structure enabled precise determination of the
+in-plane self-energy dominated by electron-electron scattering. Through
+analysis of this self-energy and the Fermi-liquid cut-off energy scale, we find
+-- in contrast to hole-doped cuprates -- a momentum isotropic and comparatively
+weak electron correlation in PLCCO. Yet, the self-energies extracted from
+multiple oxide systems combine to demonstrate a logarithmic divergent relation
+between the quasiparticle scattering rate and mass. This constitutes a
+spectroscopic version of the Kadowaki-Woods relation with an important merit --
+the demonstration of Fermi liquid quasiparticle lifetime and mass being set by
+a single energy scale.",2006.13119v2
+2020-06-30,"Oxidation states, Thouless' pumps, and non-trivial ionic transport in non-stoichiometric electrolytes","Thouless' quantization of adiabatic particle transport permits to associate
+an integer topological charge with each atom of an electronically gapped
+material. If these charges are additive and independent of atomic positions,
+they provide a rigorous definition of atomic oxidation states and atoms can be
+identified as integer-charge carriers in ionic conductors. Whenever these
+conditions are met, charge transport is necessarily convective, i.e. it cannot
+occur without substantial ionic flow, a transport regime that we dub trivial.
+We show that the topological requirements that allow these conditions to be
+broken are the same that would determine a Thouless' pump mechanism if the
+system were subject to a suitably defined time-periodic Hamiltonian. The
+occurrence of these requirements determines a non-trivial transport regime
+whereby charge can flow without any ionic convection, even in electronic
+insulators. These results are first demonstrated with a couple of simple
+molecular models that display a quantum pump mechanism upon introduction of a
+fictitious time dependence of the atomic positions along a closed loop in
+configuration space. We finally examine the impact of our findings on the
+transport properties of non-stoichiometric alkali-halide melts, where the same
+topological conditions that would induce a quantum pump mechanism along certain
+closed loops in configuration space also determine a non-trivial transport
+regime such that most of the total charge current results to be uncorrelated
+from the ionic ones.",2006.16749v2
+2020-08-10,On the suitability of hBN as an insulator for 2D material-based ultrascaled CMOS devices,"Complementary metal oxide semiconductor (CMOS) logic circuits at the ultimate
+scaling limit place the utmost demands on the properties of all materials
+involved. The requirements for semiconductors are well explored and could
+possibly be satisfied by a number of layered two-dimensional (2D) materials,
+like for example transition-metal dichalcogenides or black phosphorus. The
+requirements for the gate insulator are arguably even more challenging and
+difficult to meet. In particular the combination of insulator to semiconductor
+which forms the central element of the metal oxide semiconductor field effect
+transistor (MOSFET) has to be of superior quality in order to build competitive
+devices. At the moment, hexagonal boron nitride (hBN) is the most common
+two-dimensional insulator and widely considered to be the most promising gate
+insulator in nanoscaled 2D material-based transistors. Here, we critically
+assess the material parameters of hBN and conclude that while its properties
+render hBN an ideal candidate for many applications in 2D nanoelectronics, hBN
+is most likely not suitable as a gate insulator for ultrascaled CMOS devices.",2008.04144v1
+2020-08-12,Controlled electrochemical functionalization of CNT fibers: structure-chemistry relations and application in current collector-free all-solid supercapacitors,"Chemical functionalization of nanocarbons is an important strategy to produce
+electrochemical systems with higher energy/power density by generating surface
+functional groups with additional faradaic contribution, by increasing their
+surface area and correspondent capacitive contribution and by improving
+compatibility with aqueous electrolytes and other active materials, such as
+pseudocapacitive metal-oxides. Here we present an electrochemical method to
+simultaneously swell and functionalize large electrodes consisting of fabrics
+of macroscopic fibers of carbon nanotubes that renders the material hydrophilic
+and produces a substantial increase of specific capacitance and energy density
+in aqueous electrolytes. Through in-depth characterization of the carbon
+nanotube fibres (CNTF) by Raman spectroscopy, transmission electron microscopy,
+X-ray photoelectrocn spectroscopy (XPS) and small-angle X-ray scattering (SAXS)
+we identify various contributions to such improvements, including surface
+oxidation, tubular unzipping, debundling and inter-bundle swelling. Changes in
+hydrophilicity of functionalized CNTF are determined by analyzing the dynamics
+of spreading of polar and nonpolar liquids in the electrode. The extracted
+contact angles and polar and dispersive surface energy components for different
+treatment conditions are in agreement with changes in dipole-moment obtained by
+XPS. Finally, functionalized CNTF electrodes were employed in current
+collector-free solid flexible supercapacitors, which show enhanced
+electrochemical properties compared to as-produced hydrophobic ones.",2008.05340v1
+2020-08-14,Optical Identification of Materials Transformations in Oxide Thin Films,"Recent advances in high-throughput experimentation for combinatorial studies
+have accelerated the discovery and analysis of materials across a wide range of
+compositions and synthesis conditions. However, many of the more powerful
+characterization methods are limited by speed, cost, availability, and/or
+resolution. To make efficient use of these methods, there is value in
+developing approaches for identifying critical compositions and conditions to
+be used as a-priori knowledge for follow-up characterization with
+high-precision techniques, such as micron-scale synchrotron based X-ray
+diffraction (XRD). Here we demonstrate the use of optical microscopy and
+reflectance spectroscopy to identify likely phase-change boundaries in thin
+film libraries. These methods are used to delineate possible metastable phase
+boundaries following lateral-gradient Laser Spike Annealing (lg-LSA) of oxide
+materials. The set of boundaries are then compared with definitive
+determinations of structural transformations obtained using high-resolution
+XRD. We demonstrate that the optical methods detect more than 95% of the
+structural transformations in a composition-gradient La-Mn-O library and a
+Ga$_2$O$_3$ sample, both subject to an extensive set of lg-LSA anneals. Our
+results provide quantitative support for the value of optically-detected
+transformations as a priori data to guide subsequent structural
+characterization, ultimately accelerating and enhancing the efficient
+implementation of $\mu$m-resolution XRD experiments.",2008.06419v1
+2020-08-22,Indium-Tin-Oxide Transistors with One Nanometer Thick Channel and Ferroelectric Gating,"In this work, we demonstrate high performance indium-tin-oxide (ITO)
+transistors with the channel thickness down to 1 nm and ferroelectric
+Hf0.5Zr0.5O2 as gate dielectric. On-current of 0.243 A/mm is achieved on
+sub-micron gate-length ITO transistors with a channel thickness of 1 nm, while
+it increases to as high as 1.06 A/mm when the channel thickness increases to 2
+nm. A raised source/drain structure with a thickness of 10 nm is employed,
+contributing to a low contact resistance of 0.15 {\Omega}mm and a low contact
+resistivity of 1.1{\times}10-7 {\Omega}cm2. The ITO transistor with a recessed
+channel and ferroelectric gating demonstrates several advantages over 2D
+semiconductor transistors and other thin film transistors, including large-area
+wafer-size nanometer thin film formation, low contact resistance and contact
+resistivity, atomic thin channel being immunity to short channel effects, large
+gate modulation of high carrier density by ferroelectric gating, high-quality
+gate dielectric and passivation formation, and a large bandgap for the
+low-power back-end-of-line (BEOL) CMOS application.",2008.09881v1
+2020-08-27,Predicting band gaps and band-edge positions of oxide perovskites using DFT and machine learning,"Density functional theory within the local or semilocal density
+approximations (DFT-LDA/GGA) has become a workhorse in electronic structure
+theory of solids, being extremely fast and reliable for energetics and
+structural properties, yet remaining highly inaccurate for predicting band gaps
+of semiconductors and insulators. Accurate prediction of band gaps using
+firstprinciples methods is time consuming, requiring hybrid functionals,
+quasi-particle GW, or quantum Monte Carlo methods. Efficiently correcting
+DFT-LDA/GGA band gaps and unveiling the main chemical and structural factors
+involved in this correction is desirable for discovering novel materials in
+high-throughput calculations. In this direction, we use DFT and machine
+learning techniques to correct band gaps and band-edge positions of a
+representative subset of ABO3 perovskite oxides. Relying on results of HSE06
+hybrid functional calculations as target values of band gaps, we find a
+systematic band gap correction of ~1.5 eV for this class of materials, where ~1
+eV comes from downward shifting the valence band and ~0.5 eV from uplifting the
+conduction band. The main chemical and structural factors determining the band
+gap correction are determined through a feature selection procedure.",2008.12412v2
+2020-09-06,$In$ $situ$ and $operando$ characterisation techniques for solid oxide electrochemical cells: Recent advances,"Oxygen activity and surface stability are two key parameters in the search
+for advanced materials for intermediate temperature solid oxide electrochemical
+cells, as overall device performance depends critically on them. In particular
+$in$ $situ$ and $operando$ characterisation techniques have accelerated the
+understanding of degradation processes and the identification of active sites,
+motivating the design and synthesis of improved, nanoengineered materials. In
+this short topical review we report on the latest developments of various
+sophisticated $in$ $situ$ and $operando$ characterization techniques, including
+Transmission and Scanning Electron Microscopy (TEM and SEM), surface-enhanced
+Raman spectroscopy (SERS), Electrochemical Impedance Spectroscopy (EIS), X-ray
+Diffraction (XRD) and synchrotron based X-ray photoelectron spectroscopy (XPS)
+and X-ray absorption spectroscopy (XAS), among others. We focus on their use in
+three emerging topics, namely: (i) the analysis of general electrochemical
+reactions and the surface defect chemistry of electrode materials; (ii) the
+evolution of electrode surfaces achieved by nanoparticle exsolution for
+enhanced oxygen activity and (iii) the study of surface degradation caused by
+Sr segregation, leading to reduced durability. For each of these topics we
+highlight the most remarkable examples recently published. We anticipate that
+ongoing improvements in the characterisation techniques and especially a
+complementary use of them by multimodal approaches will lead to improved
+knowledge of $operando$ processes, hence allowing a significant advancement in
+cell performance in the near future.",2009.02693v1
+2020-09-07,Resolving Few-Layer Antimonene/Graphene Heterostructures,"Two-dimensional (2D) antimony (Sb, antimonene) recently attracted interest
+due to its peculiar electronic properties and its suitability as anode material
+in next generation batteries. Sb however exhibits a large
+polymorphic/allotropic structural diversity, which is also influenced by the
+Sb's support. Thus understanding Sb heterostructure formation is key in 2D Sb
+integration. Particularly 2D Sb/graphene interfaces are of prime importance as
+contacts in electronics and electrodes in batteries. We thus study here
+few-layered 2D Sb/graphene heterostructures by atomic-resolution (scanning)
+transmission electron microscopy. We find the co-existence of two Sb
+morphologies: First is a 2D growth morphology of layered beta-Sb with
+beta-Sb(001)||graphene(001) texture. Second are one-dimensional (1D) Sb
+nanowires which can be matched to beta-Sb with beta-Sb[2-21] perpendicular to
+graphene(001) texture and are structurally also closely related to
+thermodynamically non-preferred cubic Sb(001)||graphene(001). Importantly, both
+Sb morphologies show rotational van-der-Waals epitaxy with the graphene
+support. Both Sb morphologies are well resilient against environmental bulk
+oxidation, although superficial Sb-oxide layer formation merits consideration,
+including formation of novel epitaxial Sb2O3(111)/beta-Sb(001)
+heterostructures. Exact Sb growth behavior is sensitive on employed processing
+and substrate properties including, notably, the nature of the support
+underneath the direct graphene support. This introduces the substrate
+underneath a direct 2D support as a key parameter in 2D Sb heterostructure
+formation. Our work provides insights into the rich phase and epitaxy landscape
+in 2D Sb and 2D Sb/graphene heterostructures.",2009.03097v1
+2020-09-08,Unveiling the role of carbon defects in the exceptional narrowing of m-ZrO2 bandgap for enhanced photoelectrochemical water splitting performance,"The development of efficient photoelectrodes via defect engineering of
+wide-band gap metal oxides has been the prime focus for many years.
+Specifically, the effect of carbon defects in wide-band gap metal oxides on
+their performance in photoelectrochemical (PEC) applications raised numerous
+controversies and still elusive. Herein, the effect of various carbon defects
+in m-ZrO2 was investigated using the density functional theory to probe the
+thermodynamic, electronic, and optical properties of the defective structures
+against pristine m-ZrO2. The defect formation energies revealed that elevating
+the temperature promotes and facilitates the formation of carbon defects.
+Moreover, the binding energies confirmed the stability of all studied complex
+carbon defects. Furthermore, the band edge positions against the redox
+potentials of water species revealed that all the studied defective structures
+can serve as photoanodes for water splitting. Additionally, CO3c (carbon atom
+substituted O3c site) was the only defective structure that exhibited slight
+straddling of the redox potentials of water. Importantly, all investigated
+defective structures enhanced light absorption with different optical
+activities. Finally, CO3cVO3c (carbon atom substituted O3c associated with O3c
+vacancy) defective m-ZrO2 enjoyed low direct band gap (1.9 eV), low defect
+formation energy, low exciton binding energy, high mobility of charge carriers,
+fast charge transfer, and low recombination rate. Concurrently, its optical
+properties were exceptional in terms of high absorption, low reflectivity and
+improved static dielectric constant. Hence, the study recommends CO3cVO3c
+defective m-ZrO2 as the leading candidate to serve as a photoanode for PEC
+applications.",2009.03674v1
+2020-09-18,Nanoscale structural and electrical properties of graphene grown on AlGaN by catalyst-free chemical vapor deposition,"The integration of graphene (Gr) with nitride semiconductors is highly
+interesting for applications in high-power/high-frequency electronics and
+optoelectronics. In this work, we demonstrated the direct growth of Gr on
+Al0.5Ga0.5N/sapphire templates by propane (C3H8) chemical vapor deposition
+(CVD) at temperature of 1350{\deg}C. After optimization of the C3H8 flow rate,
+a uniform and conformal Gr coverage was achieved, which proved beneficial to
+prevent degradation of AlGaN morphology. X-ray photoemission spectroscopy (XPS)
+revealed Ga loss and partial oxidation of Al in the near-surface AlGaN region.
+Such chemical modification of a 2 nm thick AlGaN surface region was confirmed
+by cross-sectional scanning transmission electron microscopy (STEM) combined
+with electron energy loss spectroscopy (EELS), which also showed the presence
+of a bilayer of Gr with partial sp2/sp3 hybridization. Raman spectra indicated
+that the deposited Gr is nanocrystalline (with domain size 7 nm) and
+compressively strained. A Gr sheet resistance of 15.8 kOhm/sq was evaluated by
+four-point-probe measurements, consistently with the nanocrystalline nature of
+these films. Furthermore, nanoscale resolution current mapping by conductive
+atomic force microscopy (C-AFM) indicated local variations of the Gr carrier
+density at a mesoscopic scale, which can be ascribed to changes in the charge
+transfer from the substrate due to local oxidation of AlGaN or to the presence
+of Gr wrinkles.",2009.08673v1
+2020-09-18,Tail-states induced semiconductor-toconductor like transition under sub-bandgap light excitation in the zinc-tin-oxide photothinfilm transistors,"We report on a giant persistent photoconductivity (PPC) induced
+semiconductor-to-conductor like transition in zinc-tin-oxide (ZTO)
+photo-thinfilm transistors (TFT). The active ZTO channel layer was prepared by
+remote-plasma reactive sputtering and possesses an amorphous structure. Under
+subbandgap excitation of ZTO with UV light, the photocurrent reaches as high as
+~10 -4 A (a photo-to-dark current ratio of ~10 7) and remains close to this
+high value after switching off the light. During this time, the ZTO TFT
+exhibits gigantic PPC with long-lasting recovery time, which leads the ZTO
+compound to undergo a semiconductor-to-conductor like transition. In the
+present case, the conductivity changes over six orders of magnitude, from ~10-7
+to 0.92 {\Omega} -1cm-1. After UV exposure, the ZTO compound can potentially
+remain in the conducting state for up to a month. The underlying physics of the
+observed PPC effect is investigated by studying defects (deep-states and
+tail-states) by employing a discharge current analysis (DCA) technique.
+Findings from the DCA study reveal direct evidence for the involvement of
+sub-gap tail-states of the ZTO in the giant PPC, while deep-states contribute
+to mild PPC.",2009.08714v1
+2020-09-20,Remarkable antibacterial activity of reduced graphene oxide functionalized by copper ions,"Despite long-term efforts for exploring antibacterial agents or drugs, it
+remains challenging how to potentiate antibacterial activity and meanwhile
+minimize toxicity hazards to the environment. Here, we experimentally show that
+the functionality of reduced graphene oxide (rGO) through copper ions displays
+selective antibacterial activity significantly stronger than that of rGO itself
+and no toxicity to mammalian cells. Remarkably, this antibacterial activity is
+two orders of magnitude greater than the activity of its surrounding copper
+ions. We demonstrate that the rGO is functionalized through the cation-${\pi}$
+interaction to massively adsorb copper ions to form a rGO-copper composite in
+solution and result in an extremely low concentration level of surrounding
+copper ions (less than ~0.5 ${\mu}M$). These copper ions on rGO are positively
+charged and strongly interact with negatively charged bacterial cells to
+selectively achieve antibacterial activity, while rGO exhibits the
+functionality to not only actuate rapid delivery of copper ions and massive
+assembly onto bacterial cells but also result in the valence shift in the
+copper ions from Cu$^{2+}$ into Cu$^{+}$ which greatly enhances the
+antibacterial activity. Notably, this functionality of rGO through
+cation-${\pi}$ interaction with copper ions can similarly achieve algaecidal
+activity but does not exert cytotoxicity against neutrally charged mammalian
+cells. The remarkable selective antibacterial activity from the rGO
+functionality as well as the inherent broad-spectrum-antibacterial physical
+mechanism represents a significant step toward the development of a novel
+antibacterial material and reagent without environmental hazards for practical
+application.",2009.09365v1
+2020-09-30,Domain Control by Adjusting Anisotropic Stress in Pyrochlore Oxide Cd2Re2O7,"The 5d pyrochlore oxide Cd2Re2O7 exhibits successive phase transitions from a
+cubic pyrochlore structure (phase I) to a tetragonal structure without
+inversion symmetry below Ts1 of ~200 K (phase II) and further to another
+noncentrosymmetric tetragonal structure below Ts2 of ~120 K (phase III). The
+two low-temperature phases may be characterized by odd-parity multipolar orders
+induced by the Fermi liquid instability of the spin-orbit-coupled metal. To
+control the tetragonal domains generated by the transitions and to obtain a
+single-domain crystal for the measurements of anisotropic properties, we
+prepared single crystals with the (0 0 1) surface and applied biaxial and
+uniaxial stresses along the plane. Polarizing optical microscopy observations
+revealed that inducing a small strain of approximately 0.05% could flip the
+twin domains ferroelastically in a reversible fashion at low temperatures,
+which evidences that the tetragonal deformation switches at Ts2 between c > a
+for phase II and c < a for phase III. Resistivity measurements using
+single-domain crystals under uniaxial stress showed that the anisotropy was
+maximum at around Ts2 and turned over across Ts2: resistivity along the c axis
+is larger (smaller) than that along the a axis by ~25% for phase II (III) at
+around Ts2. These large anisotropies probably originate from spin-dependent
+scattering in the spin-split Fermi surfaces of the cluster electric toroidal
+quadrupolar phases of Cd2Re2O7.",2009.14443v1
+2020-10-05,Proof-of-concept thermoelectric oxygen sensor exploiting oxygen mobility of GdBaCo2O5+δ,"In this paper, we demonstrate a proof-of-concept oxygen sensor based on the
+thermoelectric principle using polycrystalline $GdBaCo_2O_{5+\delta}$ where
+0.45<${\delta}$<0.55 (GDCO). The lattice oxygen in layered double perovskite
+oxides is highly susceptible to the ambient oxygen partial pressure. The
+as-synthesized GDCO sample processed in ambient conditions shows pure
+orthorhombic ($P_{mmm}$ space group) phase and a ${\delta}$-value close to 0.5
+as confirmed from X-ray diffraction reitveld refinement. The X-ray
+photoelectron spectroscopy shows significant $Co^{3+}$ oxidation state in
+non-octahedral sites in addition to $Co^{3+}$ and $Co^{4+}$ in octahedral
+sites. The insulator-to-metal transition (MIT) is observed at nearly 340 K as
+seen in electrical resistivity and seebeck coefficient measurements. The
+seebeck coefficient shows a large change of about 10-13 $\mu$V/K with time
+constant of ~20 sec, at room temperature (300 K) when the gas ambience changes
+from 100% oxygen to 100% nitrogen and vice versa, under a constant temperature
+gradient of 1 K. The response in seebeck is found to be particularly large
+below MIT. The diffusion of oxygen into the lattice leading to hole doping
+shows a large change in carrier concentration resulting in a large change in
+the seebeck coefficient in insulating state. On the other hand, due to
+insignificant increase in already large carrier concentration in metallic state
+the change in seebeck is minimal. Nevertheless, below MIT the response is
+fairly reproducible within stoichiometry ${\delta}$ = 0.5 $\pm$ 0.05. This
+principle shall be of significant utility to design the oxygen sensors which
+work at room temperature or even cryogenic temperatures.",2010.01783v1
+2020-10-06,Li4-xGe1-xPxO4 a potential solid-state electrolyte for all-oxide microbatteries,"Solid-state electrolytes for Li-ion batteries are attracting growing interest
+as they allow building safer batteries, also using lithium metal anodes. Here
+we studied a compound in the lithium superionic conductor (LISICON) family,
+i.e. Li4-xGe1-xPxO4 (LGPO). Thin films were deposited via pulsed laser
+deposition and their electrical properties were compared with ceramic pellets.
+A detailed characterization of the micro structure shows that thin films can be
+deposited fully crystalline at higher temperatures but also partially amorphous
+at room temperature. The conductivity is not strongly influenced by the
+presence of grain boundaries, exposure to air or lithium deficiencies.
+First-principles molecular dynamics simulations were employed to calculate the
+lithium ion diffusion profile and the conductivity at various temperatures of
+the ideal LGPO crystal. Simulations gives the upper limit of conductivity for a
+defect free crystal, which is in the range of 10-2 S cm-1 at 300 deg. The ease
+of thin film fabrication, the room-temperature Li-ion conductivity in the range
+of a few microS cm-1 make LGPO a very appealing electrolyte material for thin
+film all-solid-state all-oxide microbatteries.",2010.02608v1
+2020-10-15,Electrolytes for Li-ion all-solid-state batteries: a first-principles comparative study of Li10GeP2O12 and Li10GeP2S12 in the LISICON and LGPS phases,"In this work we address Li-ion diffusion in thio-LISICON materials and in
+their oxide counterparts, exploring both the orthorhombic and tetragonal phases
+of Li10GeP2S12(LGPS) and Li10GeP2O12(LGPO) through extended Car-Parrinello
+molecular dynamics in the canonical and isobaric-isothermal ensemble. The
+(quasi-)orthorhombic and tetragonal phases are studied both for the oxide and
+for the sulfide, with the aim of comparing their conductivity with the same
+approach; out of these four case studies, tetragonal LGPO has not been reported
+and, while dynamically stable, it sits (0.04 Ha/formula unit) above
+orthorhombic LGPO. We calculate activation energies for diffusion of 0.18 eV
+and 0.23 eV for tetragonal and orthorhombic LGPS, and of 0.22 eV and 0.34eV for
+tetragonal and orthorhombic LGPO. In line with experiments, we find
+orthorhombic LGPO orders of magnitude less conductive, at room temperature,
+than the two sulfide systems. However, this is not the case for tetragonal
+LGPO, which, although less stable than its orthorhombic allotrope, shows at
+room temperature a conductivity comparable to orthorhombic and tetragonal LGPS,
+and, if synthesized, could make a very attractive Li-ion conductor.",2010.08068v1
+2020-10-21,Rydberg Excitons in Synthetic Cuprous Oxide (Cu$_2$O),"High-lying Rydberg states of Mott-Wannier excitons are receiving considerable
+interest due to the possibility of adding long-range interactions to the
+physics of exciton-polaritons. Here, we study Rydberg excitation in bulk
+synthetic cuprous oxide grown by the optical float zone technique and compare
+the result with natural samples. X-ray characterization confirms both materials
+are mostly single crystal, and mid-infrared transmission spectroscopy revealed
+little difference between synthetic and natural material. The synthetic samples
+show principal quantum numbers up to $n=10$, exhibit additional absorption
+lines, plus enhanced spatial broadening and spatial inhomogeneity. Room
+temperature and cryogenic photoluminescence measurements reveal a significant
+excess of copper vacancies in the synthetic material. These measurements
+provide a route towards achieving \mbox{high-$n$} excitons in synthetic
+crystals, opening a route to scalable quantum devices.",2010.11117v1
+2020-10-23,"Air-stable, earth-abundant molten chlorides and corrosion-resistant containment for chemically-robust, high-temperature thermal energy storage for concentrated solar power","A dramatic reduction in man-made CO2 emissions could be achieved if the cost
+of electricity generated from concentrated solar power (CSP) plants could
+become competitive with fossil-fuel-derived electricity. The solar
+heat-to-electricity conversion efficiency of CSP plants may be significantly
+increased (and the associated electricity cost decreased) by operating CSP
+turbines with inlet temperatures >750 C instead of <550 C, and by using thermal
+energy storage (TES) at >750 C to allow for rapidly dispatchable and/or
+continuous electricity production. Unfortunately, earth-abundant
+MgCl2-KCl-based liquids currently being considered as low-cost media for
+large-scale, high-temperature TES are susceptible to oxidation in air, with
+associated undesired changes in liquid composition and enhanced corrosion of
+metal alloys in pipes and tanks containing such liquids. In this paper,
+alternative high-temperature, earth-abundant molten chlorides that are stable
+in air are identified via thermodynamic calculations. The oxidation resistance,
+and corrosion-resistant containment, of such molten chlorides at 750 C are then
+demonstrated. Such chemically-robust, low-cost TES media and effective
+containment provide critical advances towards the higher-temperature operation
+of, and lower-cost electricity generation from, CSP plants.",2010.12476v1
+2020-11-11,Voltage tunable quantum dot array by patterned Ge-nanowire based metal-oxide-semiconductor (MOS) devices,"Semiconductor quantum dots (QDs) are being regarded as the primary unit for a
+wide range of advanced and emerging technologies including electronics,
+optoelectronics, photovoltaics and biosensing applications as well as the
+domain of q-bits based quantum information processing. Such QDs are suitable
+for several novel device applications for their unique property of confining
+carriers 3-dimensionally creating discrete quantum states. However, the
+realization of such QDs in practice exhibits serious challenge regarding their
+fabrication in array with desired scalability and repeatability as well as
+control over the quantum states at room temperature. In this context, the
+current work reports the fabrication of an array of highly scaled Ge-nanowire
+(radius ~25 nm) based vertical metal-oxide-semiconductor devices that can
+operate as voltage tunable quantum dots at room temperature. The electrons in
+such nanowire experience a geometrical confinement in the radial direction,
+whereas, they can be confined axially by tuning the applied bias in order to
+manipulate the quantum states. Such quantum confinement of electrons has been
+confirmed from the step-like responses in the room temperature
+capacitance-voltage (C-V) characteristics at relatively low frequency (200
+kHz). Each of such steps has observed to encompass convolution of the quantized
+states occupying ~6 electronic charges. The details of such carrier confinement
+are analyzed in the current work by theoretically modeling the device transport
+properties based on non-equilibrium Green's function (NEGF) formalism.",2011.06580v1
+2020-11-26,Oxidising and carburising catalyst conditioning for the controlled growth and transfer of large crystal monolayer hexagonal boron nitride,"Hexagonal boron nitride (h-BN) is well-established as a requisite support,
+encapsulant and barrier for 2D material technologies, but also recently as an
+active material for applications ranging from hyperbolic metasurfaces to room
+temperature single-photon sources. Cost-effective, scalable and high quality
+growth techniques for h-BN layers are critically required. We utilise
+widely-available iron foils for the catalytic chemical vapour deposition (CVD)
+of h BN and report on the significant role of bulk dissolved species in h-BN
+CVD, and specifically, the balance between dissolved oxygen and carbon. A
+simple pre-growth conditioning step of the iron foils enables us to tailor an
+error-tolerant scalable CVD process to give exceptionally large h-BN monolayer
+domains. We also develop a facile method for the improved transfer of as-grown
+h-BN away from the iron surface by means of the controlled humidity oxidation
+and subsequent rapid etching of a thin interfacial iron oxide; thus, avoiding
+the impurities from the bulk of the foil. We demonstrate wafer-scale (2 inch)
+production and utilise this h-BN as a protective layer for graphene towards
+integrated (opto) electronic device fabrication.",2011.13176v1
+2020-11-29,Dispersing and semi-flat bands in the wide band gap two-dimensional semiconductor bilayer silicon oxide,"Epitaxial bilayer silicon oxide is a transferable two-dimensional material
+predicted to be a wide band gap semiconductor, with potential applications for
+deep UV optoelectronics, or as a building block of van der Waals
+heterostructures. The prerequisite to any sort of such applications is the
+knowledge of the electronic band structure, which we unveil using
+angle-resolved photoemission spectroscopy and rationalise with the help of
+density functional theory calculations. We discover dispersing bands related to
+electronic delocalisation within the top and bottom planes of the material,
+with two linear crossings reminiscent of those predicted in bilayer AA-stacked
+graphene, and semi-flat bands stemming from the chemical bridges between the
+two planes. This band structure is robust against exposure to air, and can be
+controled by exposure to oxygen. We provide an experimental lower-estimate of
+the band gap size of 5 eV and predict a full gap of 7.36 eV using density
+functional theory calculations.",2011.14376v2
+2021-02-01,Atomistic calculations of charged point defects at grain boundaries in SrTiO$_3$,"Oxygen vacancies have been identified to play an important role in
+accelerating grain growth in polycrystalline perovskite-oxide ceramics. In
+order to advance the fundamental understanding of growth mechanisms at the
+atomic scale, classical atomistic simulations were carried out to investigate
+the atomistic structures and oxygen vacancy formation energies at grain
+boundaries in the prototypical perovskite-oxide material SrTiO$_3$. In this
+work, we focus on two symmetric tilt grain boundaries, namely
+$\Sigma$5(310)[001] and $\Sigma$5(210)[001]. A one-dimensional continuum model
+is adapted to determine the electrostatic potential induced by charged lattice
+planes in atomistic structure models containing grain boundaries and point
+defects. By means of this model, electrostatic artifacts, which are inherent to
+supercell models with periodic or open boundary conditions, can be taken into
+account and corrected properly. We report calculated formation energies of
+oxygen vacancies on all the oxygen sites across boundaries between two
+misoriented grains, and we analyze and discuss the formation-energy values with
+respect to local charge densities at the vacant sites.",2102.01016v2
+2021-02-03,Selective Enhancement in Phonon Scattering leads to High Thermoelectric Figure of Merit in ZnO -- Graphene Oxide Core-shell Nanohybrids,"ZnO is a promising candidate as an environment friendly thermoelectric (TE)
+material. However, the poor TE figure of merit (zT) needs to be addressed to
+achieve significant TE efficiency for commercial applications. Here we
+demonstrate that selective enhancement in phonon scattering leads to increase
+in zT of RGO encapsulated Al-doped ZnO core shell nanohybrids, synthesized via
+a facile and scalable method. The incorporation of 1 at% Al with 1.5 wt% RGO
+into ZnO (AGZO) has been found to show significant enhancement in zT (=0.52 at
+1100 K) which is an order of magnitude larger compared to that of bare undoped
+ZnO. Photoluminescence and X-ray photoelectron spectroscopy measurements
+confirm that RGO encapsulation significantly quenches surface oxygen vacancies
+in ZnO along with nucleation of new interstitial Zn donor states. Tunneling
+spectroscopy reveals that the band gap of ~ 3.4 eV for bare ZnO reduces
+effectively to ~ 0.5 eV upon RGO encapsulation, facilitating charge transport.
+The electrical conductivity enhancement also benefits from the more than 95%
+densification achieved, using the spark plasma sintering method, which aids
+reduction of GO into RGO. The same Al doping and RGO capping synergistically
+brings about drastic reduction of thermal conductivity, through enhanced
+phonon-phonon and point defect-phonon scatterings. These opposing effects on
+electrical and thermal conductivities enhances the power factors as well as the
+zT value. Overall, a practically viable route for synthesis of oxide - RGO TE
+material which could find its practical applications for the high-temperature
+TE power generation.",2102.01896v1
+2021-02-04,Structural phase transition and its consequences on optical behavior of LaV$_{1-x}$Nb$_x$O$_4$,"We present the structural, electronic, vibrational, and photoluminescence
+properties of polycrystalline LaV$_{1-x}$Nb$_x$O$_4$ ($x =$ 0--0.2) samples at
+room temperature. The substitution of Nb at the V site shows the fascinating
+structural and optical behavior due to their isoelectronic character and larger
+ionic radii of Nb$^{5+}$ as compared to the V$^{5+}$. The Rietveld refinement
+of x-ray diffraction patterns demonstrate that the $x=$ 0 sample exist in a
+monoclinic (P2$_1$/n) phase, whereas for the $x >$ 0, both monoclinic and
+scheelite-tetragonal (I4$_1$/a) phases co-exist in a certain proportion.
+Interestingly, a monotonous enhancement in the Raman spectral intensity with Nb
+substitution is correlated with the substitution induced increase in the
+scheelite-tetragonal phase. The x-ray absorption measurements reveal that the
+La ions exist in a trivalent oxidation state, while V and Nb cations possess 5+
+oxidation state in tetrahedral coordination. Moreover, the Fourier-transform
+infrared (FTIR) spectra indicate that the Nb substitution give origin to some
+additional IR modes owing to the deformation of the VO$_4$$^{3-}$ tetrahedra
+and mixing of monoclinic and tetragonal phases. The photoluminescence
+measurements on these samples exhibit broadband spectra and their deconvolution
+designate the availability of more than one electron-hole pairs recombination
+center.",2102.02442v2
+2021-02-07,Quantum Conductors Formation and Resistive Switching Memory Effects in Zirconia Nanotubes,"The development prospects of memristive elements for non-volatile memory with
+use of the metal-dielectric-metal sandwich structures with a thin oxide layer
+are due to the possibility of reliable forming the sustained functional states
+with quantized resistance. In the paper we study the properties of fabricated
+memristors based on the non-stoichiometric $ZrO_2$ nanotubes in different
+resistive switching modes. Anodic oxidation of the $Zr$ foil has been used to
+synthesize a zirconia layer of $1.7$ $\mu$$m$ thickness, consisting of an
+ordered array of vertically oriented nanotubes with outer diameter of 75 nm.
+$Zr/ZrO_2/Au$ sandwich structures have been fabricated by mask magnetron
+deposition. The effects of resistive switching in the $Zr/ZrO_2/Au$ memristors
+in unipolar and bipolar modes have been investigated. The resistance ratios
+$\geq3\cdot10^4$ between high-resistance (HRS) and low-resistance (LRS) states
+have been evaluated. It has been founded the conductivity of LRS is quantized
+in a wide range with minimum value of $0.5G_0=38.74$ $\mu$$S$ due to the
+formation of quantum conductors based on oxygen vacancies ($V_O$). Resistive
+switching mechanisms of $Zr/ZrO_2/Au$ memristors with allowing for migration of
+$V_O$ in an applied electric field have been proposed. It has been shown that
+the ohmic type and space charge limited conductivities are realized in the LRS
+and HRS, correspondingly. We present the results which can be used for
+development of effective memristors based on functional $Zr/ZrO_2/Au$
+nanolayered structure with multiple resistive states and high resistance ratio.",2102.03764v1
+2021-02-10,Control of the metal-insulator transition in NdNiO$_3$ thin films through the interplay between structural and electronic properties,"Heteroepitaxy offers a new type of control mechanism for the crystal
+structure, the electronic correlations, and thus the functional properties of
+transition-metal oxides. Here, we combine electrical transport measurements,
+high-resolution scanning transmission electron microscopy (STEM), and density
+functional theory (DFT) to investigate the evolution of the metal-to-insulator
+transition (MIT) in NdNiO$_3$ films as a function of film thickness and
+NdGaO$_3$ substrate crystallographic orientation. We find that for two
+different substrate facets, orthorhombic (101) and (011), modifications of the
+NiO$_6$ octahedral network are key for tuning the transition temperature
+$T_{\text{MIT}}$ over a wide temperature range. A comparison of films of
+identical thickness reveals that growth on [101]-oriented substrates generally
+results in a higher $T_{\text{MIT}}$, which can be attributed to an enhanced
+bond-disproportionation as revealed by the DFT+$U$ calculations, and a tendency
+of [011]-oriented films to formation of structural defects and stabilization of
+non-equilibrium phases. Our results provide insights into the
+structure-property relationship of a correlated electron system and its
+evolution at microscopic length scales and give new perspectives for the
+epitaxial control of macroscopic phases in metal-oxide heterostructures.",2102.05415v2
+2021-02-10,Atomic-scale insights into electro-steric substitutional chemistry of cerium oxide,"Cerium oxide (ceria, CeO2) is one of the most promising mixed ionic and
+electronic conducting materials. Previous atomistic analysis has covered widely
+the effects of substitution on oxygen vacancy migration. However, an in-depth
+analysis of the role of cation substitution beyond trivalent cations has rarely
+been explored. Here, we investigate soluble monovalent, divalent, trivalent and
+tetravalent cation substituents. By combining classical simulations and quantum
+mechanical calculations, we provide an insight into defect association energies
+between substituent cations and oxygen vacancies as well as their effects on
+the diffusion mechanisms. Our simulations indicate that oxygen ionic
+diffusivity of subvalent cation-substituted systems follows the order Gd>Ca>Na.
+With the same charge, a larger size mismatch with Ce cation yields a lower
+oxygen ionic diffusivity, i.e., Na>K, Ca>Ni, Gd>Al. Based on these trends, we
+identify species that could tune the oxygen ionic diffusivity: we estimate that
+the optimum oxygen vacancy concentration for achieving fast oxygen ionic
+transport is 2.5% for GdxCe1-xO2-x/2, CaxCe1-xO2-x and NaxCe1-xO2-3x/2 at 800
+K. Remarkably, such a concentration is not constant and shifts gradually to
+higher values as the temperature is increased. We find that co-substitutions
+can enhance the impact of the single substitutions beyond that expected by
+their simple addition. Furthermore, we identify preferential oxygen ion
+migration pathways, which illustrate the electro-steric effects of substituent
+cations in determining the energy barrier of oxygen ion migration. Such
+fundamental insights into the factors that govern the oxygen diffusion
+coefficient and migration energy would enable design criteria to be defined for
+tuning the ionic properties of the material, e.g., by co-doping.",2102.05702v1
+2021-02-10,cryo-ePDF: Overcoming Electron Beam Damage to Study the Local Atomic Structure of Amorphous ALD Aluminum Oxide Thin Films within a TEM,"Atomic layer deposition (ALD) provides uniform and conformal thin films that
+are of interest for a range of applications. To better understand the
+properties of amorphous ALD films, we need improved understanding of their
+local atomic structure. Previous work demonstrated measurement of how the local
+atomic structure of ALD-grown aluminum oxide (AlOx) evolves in operando during
+growth by employing synchrotron high energy X-ray diffraction (HE-XRD). In this
+work, we report on efforts to employ electron diffraction pair distribution
+function (ePDF) measurements using more broadly available transmission electron
+microscope (TEM) instrumentation to study the atomic structure of amorphous
+ALD-AlOx. We observe electron beam damage in the ALD-coated samples during ePDF
+at ambient temperature and successfully mitigate this beam damage using ePDF at
+cryogenic temperatures (cryo-ePDF). We employ cryo-ePDF and Reverse Monte Carlo
+(RMC) modeling to obtain structural models of ALD-AlOx coatings formed at a
+range of deposition temperatures from 150-332{\deg}C. From these model
+structures, we derive structural metrics including stoichiometry, pair
+distances, and coordination environments in the ALD-AlOx films as a function of
+deposition temperature. The structural variations we observe with growth
+temperature are consistent with temperature-dependent changes in the surface
+hydroxyl density on the growth surface. The sample preparation and cryo-ePDF
+procedures we report here can be used for routine measurement of ALD-grown
+amorphous thin films to improve our understanding of the atomic structure of
+these materials, establish structure-property relationships, and help
+accelerate the timescale for the application of ALD to address technological
+needs.",2102.05726v1
+2021-02-14,Theoretical design study of FWM in silicon nitride waveguides with integrated graphene oxide films,"We theoretically investigate and optimize four-wave mixing (FWM) in silicon
+nitride (SiN) waveguides integrated with two-dimensional (2D) layered graphene
+oxide (GO) films. Based on extensive previous measurements of the material
+parameters of the GO films, we perform detailed analysis for the influence of
+device parameters including waveguide geometry, GO film thickness, length, and
+coating position on the FWM conversion efficiency (CE) and conversion bandwidth
+(CB). The influence of dispersion and photo-thermal changes in the GO films is
+also discussed. Owing to the strong mode overlap between the SiN waveguides and
+the highly nonlinear GO films, FWM in the hybrid waveguides can be
+significantly enhanced. We obtain good agreement with previous experimental
+results and show that by optimizing the device parameters to balance the
+trade-off between Kerr nonlinearity and loss, the FWM CE can be improved by as
+much as ~20.7 dB and the FWM CB can be increased by ~4.4 folds, relative to the
+uncoated waveguides. These results highlight the significantly enhanced FWM
+performance that can be achieved in SiN waveguides by integrating 2D layered GO
+films.",2102.07118v1
+2021-03-12,Numerical study of laser micro- and nano-processing of nanocomposite porous materials,"This thesis is focused on numerical simulations of the laser interaction with
+porous materials. A possibility of well-controlled processing is particularly
+important for the laser based micro-structuring of porous glass and
+nano-machining of semiconducting porous materials in the presence of metallic
+nanoparticles. To understand the periodic micro-void structures produced inside
+porous glass by femtosecond laser pulses, a detailed numerical thermodynamic
+analysis was performed. The calculation results show the possibility to control
+laser micro-machining in volume of SiO2. The obtained characteristic dimensions
+of the structures correlate with the experimental results. Comparing to the
+porous glass, the mesoporous TiO2 films loaded by Ag ions and nanoparticles
+support localized plasmon resonances. To identify the optimum parameters of the
+continuous-wave laser, a multi-physical model considering Ag nanoparticle
+growth, photo-oxidation, reduction was developed. The performed simulations
+show that the laser writing speed controls the Ag nanoparticles size. The
+thermally activated fast growth followed by the photo-oxidation was found to be
+the main reason for the writing speed-dependent size-change and temperature
+rises. Writing of mesoporous TiO2 films loaded with Ag nanoparticles by a
+pulsed laser is, furthermore, promising to provide additional possibilities in
+the generation of two kinds of nanostructures: laser-induced periodic surface
+grooves and Ag nanogratingsinside the TiO2 film. To better understand the
+effects of a pulsed laser, two multi-pulses models are developed to simulate
+the Ag nanoparticle growth. The obtained results provided new insights into
+laser micro-processing of porous material and better laser controlling over
+nanostructuring in porous semiconducting films loaded with metallic
+nanoparticles.",2103.07334v1
+2021-03-13,Enhanced coherence of all-nitride superconducting qubits epitaxially grown on silicon substrate,"Improving the coherence of superconducting qubits is a fundamental step
+towards the realization of fault-tolerant quantum computation. However,
+coherence times of quantum circuits made from conventional aluminium-based
+Josephson junctions are limited by the presence of microscopic two-level
+systems in the amorphous aluminum oxide tunnel barriers. Here, we have
+developed superconducting qubits based on NbN/AlN/NbN epitaxial Josephson
+junctions on silicon substrates which promise to overcome the drawbacks of
+qubits based on Al/AlO$_{x}$/Al junctions. The all-nitride qubits have great
+advantages such as chemical stability against oxidation, resulting in fewer
+two-level fluctuators, feasibility for epitaxial tunnel barriers that reduce
+energy relaxation and dephasing, and a larger superconducting gap of $\sim$5.2
+meV for NbN, compared to $\sim$0.3 meV for aluminium, which suppresses the
+excitation of quasiparticles. By replacing conventional MgO by a silicon
+substrate with a TiN buffer layer for epitaxial growth of nitride junctions, we
+demonstrate a qubit energy relaxation time $T$$_{1}$=16.3 $\mu$s and a
+spin-echo dephasing time $T$$_{2}$=21.5 $\mu$s. These significant improvements
+in quantum coherence are explained by the reduced dielectric loss compared to
+previously reported NbN-based qubits with MgO substrates
+($T$$_{1}$$\approx$$T$$_{2}$$\approx$0.5 $\mu$s). These results are an
+important step towards constructing a new platform for superconducting quantum
+hardware.",2103.07711v3
+2021-03-13,Water on Hot Rocky Exoplanets,"Data suggest that most rocky exoplanets with orbital period $p$ $<$ 100 d
+(""hot"" rocky exoplanets) formed as gas-rich sub-Neptunes that subsequently lost
+most of their envelopes, but whether these rocky exoplanets still have
+atmospheres is unknown. We identify a pathway by which 1-1.7 $R_{Earth}$ (1-10
+$M_{Earth}$) rocky exoplanets with orbital periods of 10-100 days can acquire
+long-lived 10-2000 bar atmospheres that are H$_2$O-dominated, with mean
+molecular weight $>$10. These atmospheres form during the planets' evolution
+from sub-Neptunes into rocky exoplanets. H$_2$O that is made by reduction of
+iron oxides in the silicate magma is highly soluble in the magma, forming a
+dissolved reservoir that is protected from loss so long as the H$_2$-dominated
+atmosphere persists. The large size of the dissolved reservoir buffers the
+H$_2$O atmosphere against loss after the H$_2$ has dispersed. Within our model,
+a long-lived, water-dominated atmosphere is a common outcome for efficient
+interaction between a nebula-derived atmosphere (peak atmosphere mass fraction
+0.1-0.6 wt%) and oxidized magma ($>$5 wt% FeO), followed by atmospheric loss.
+This idea predicts that most rocky planets that have orbital periods of 10-100
+days and that have radii within 0.1-0.2 $R_{Earth}$ of the lower edge of the
+radius valley still retain H$_2$O atmospheres. This prediction is imminently
+testable with JWST and has implications for the interpretation of data for
+transiting super-Earths.",2103.07753v1
+2021-03-15,"Good Solid-State Electrolytes Have Low, Glass-like Thermal Conductivity","Management of heat during charging and discharging of Li-ion batteries is
+critical for their safety, reliability, and performance. Understanding the
+thermal conductivity of the materials comprising batteries is crucial for
+controlling the temperature and temperature distribution in batteries. This
+work provides systemic quantitative measurements of the thermal conductivity of
+three important classes of solid electrolytes (oxides, sulfides, and halides)
+over the temperature range 150-350 K. Studies include the oxides
+Li1.5Al0.5Ge1.5(PO4)3 and Li6.4La3Zr1.4Ta0.6O12, sulfides Li2S-P2S5, Li6PS5Cl,
+and Na3PS4, and halides Li3InCl6 and Li3YCl6. Thermal conductivities of sulfide
+and halide solid electrolytes are in the range 0.45-0.70 W m-1 K-1; thermal
+conductivities of Li6.4La3Zr1.4Ta0.6O12 and Li1.5Al0.5Ge1.5(PO4)3 are 1.4 W m-1
+K-1 and 2.2 W m-1 K-1, respectively. For most of the solid electrolytes studied
+in this work, the thermal conductivity increases with increasing temperature;
+i.e., the thermal conductivity has a glass-like temperature dependence. The
+measured room-temperature thermal conductivities agree well with the calculated
+minimum thermal conductivities indicating the phonon mean-free-paths in these
+solid electrolytes are close to an atomic spacing. We attribute the low,
+glass-like thermal conductivity of the solid electrolytes investigated to the
+combination of their complex crystal structures and the atomic-scale disorder
+induced by the materials processing methods that are typically needed to
+produce high ionic conductivities.",2103.08718v1
+2021-03-22,Time-frequency analysis assisted reconstruction of ruthenium optical constants in the sub-EUV spectral range 8nm-23.75nm,"The optical constants of ruthenium in the spectral range 8 nm to 23.75 nm
+with their corresponding uncertainties are derived from the reflectance of a
+sputtered ruthenium thin film in the Extreme Ultraviolet (EUV) spectral range
+measured using monochromatized synchrotron radiation. This work emphasizes the
+correlation between structure modelling and the reconstructed optical
+parameters in a detailed inverse-problem optimization strategy. Complementary
+X-ray Reflectivity (XRR) measurements are coupled with Markov chain Monte Carlo
+(MCMC) based Bayesian inferences and quasi-model-independent methods to create
+a model factoring the sample's oxidation, contamination, and surface roughness.
+The sensitivity of the modelling scheme is tested and verified against
+contamination and oxidation. A notable approach mitigating the high
+dimensionality of the reconstruction problem is elaborated with the results of
+this work compared to two previously published datasets. The presented dataset
+is of high interest for the continuing development of Extreme Ultraviolet
+Lithography (EUVL) and EUV astronomy optical systems.",2103.11868v1
+2021-03-24,Metabolomic response of osteosarcoma cells to nanographene oxide-mediated hyperthermia,"Nanographene oxide (nGO)-mediated hyperthermia has been increasingly
+investigated as a localised, minimally invasive anticancer therapeutic
+approach. Near InfraRed (NIR) light irradiation for inducing hyperthermia is
+particularly attractive, because biological systems mostly lack chromophores
+that absorb in this spectral window, facilitating the selective heating and
+destruction of cells which have internalized the NIR absorbing-nanomaterials.
+However, little is known about biological effects accompanying nGO-mediated
+hyperthermiaat cellular and molecular levels.In this work, well-characterised
+pegylatednGOsheets with an hydrodynamic size of 300 nm were incubated with
+human Saos-2 osteosarcoma cells for 24h and their incorporation verified by
+flow cytometry and confocal microscopy. No effect on cell viability was
+observed after nGO incorporation by Saos-2 cells. However, a proliferation
+delay was observed due to the presence of nGO sheets in the cytoplasm.1H NMR
+metabolomicswas employed to screen for changes in the metabolic profile of
+cells, as this could help to improve understanding of celular responses to
+nanomaterials and provide new endpoint markers of effect.Cells incorporating
+nGO sheets showed noticeable changes in 10 metabolites compared to control
+cells, including decreased levels of several amino acids, taurine and creatine
+and increased levels of phosphocholine and uridine/adenosine nucleotides. After
+NIR irradiation, cells showed decreases in glutamate and uridine nulceotides,
+together with increases in glycerophosphocholine and adenosine monophosphate.
+Overall, this study has shown that the celular metabolome sensitively responded
+to nGO exposure and nGO-mediated hyperthermia and that NMR metabolomics is a
+powerful tool toinvestigate treatment responses.",2103.13122v1
+2021-04-07,Bulk photovoltaic effect in BaTiO$_3$-based ferroelectric oxides: An experimental and theoretical study,"The bulk photovoltaic effect exhibited by the non-centrosymmetric system
+gains research interest due to the observed large open-circuit voltage. The
+ferroelectric systems exhibiting anomalous photovoltaic effect are mostly
+crystallized with multiphase coexistence. Hence, the computational difficulty
+in building a multi-phase system restricts the detailed photovoltaic studies
+through phenomenological and shift current theory. In this work, ferroelectric
+Ba$_{1- x}$(Bi$_{0.5}$K$_{0.5}$)$_x$TiO$_3$ (BBKT) oxide is designed to
+crystallize in single-phase tetragonal symmetry with improved polarization
+characteristics, and it is found to exhibits large PV response. Both
+experimental and theoretical studies on BBKT samples reveal ~18% reduction in
+bandgap compared to the parent BaTiO$_3$. Short-circuit current measured as a
+function of light intensity and light polarization angle reveal linear and
+sinusoidal response, respectively. The observed features are in accordance with
+phenomenological theory. Remarkably, x = 0.125 sample displays ~8 times higher
+open-circuit voltage (7.39 V) than the parent compound. The enhanced PV effect
+is attributed to the large shift current along z-direction as evidenced from
+the additional charge-center shift of valence band occupied by O-2p orbital and
+conduction band occupied by Bi-6p orbital. Notably, the degenerate Bi-p$_z$
+state at conduction band minimum in BBKT favours the large shift current
+response in the z-direction.",2104.03134v1
+2021-04-12,Design of silicon waveguides for Kerr nonlinear optical performance with graphene oxide films,"The Kerr nonlinear optical performance of silicon nanowire waveguides
+integrated with 2D layered graphene oxide (GO) films is theoretically studied
+and optimized based on experimentally measured linear and nonlinear optical
+parameters of the GO films. The strong mode overlap between the silicon
+nanowires and highly nonlinear GO films yields a significantly enhanced Kerr
+nonlinearity for the hybrid waveguides. A detailed analysis for the influence
+of waveguide geometry and GO film thickness on the propagation loss, nonlinear
+parameter, and nonlinear figure of merit (FOM) is performed. The results show
+that the effective nonlinear parameter and nonlinear FOM can be increased by up
+to 52 and 79 times relative to bare silicon nanowires, respectively. Self-phase
+modulation (SPM)-induced spectral broadening of optical pulses is used as a
+benchmark to evaluate the nonlinear performance, examining the tradeoff between
+enhancing Kerr nonlinearity and minimizing loss. By optimizing the device
+parameters to balance this, a high spectral broadening factor of 27.8 can be
+achieved, more than 6 times that achieved in previous experiments. Finally, the
+influence of pulse chirp, material anisotropy, and the interplay between
+saturable absorption and SPM is also discussed, together with the comparison
+between the spectral broadening after going through GO-coated and
+graphene-coated silicon waveguides. These results provide useful guidance for
+optimizing the Kerr nonlinear optical performance of silicon waveguides
+integrated with 2D layered GO films.",2104.05836v1
+2021-04-16,Machine Learning Approaches to Learn HyChem Models,"The HyChem approach has recently been proposed for modeling high-temperature
+combustion of real, multi-component fuels. The approach combines lumped
+reaction steps for fuel thermal and oxidative pyrolysis with detailed chemistry
+for the oxidation of the resulting pyrolysis products. However, the approach
+usually shows substantial discrepancies with experimental data within the
+Negative Temperature Coefficient (NTC) regime, as the low-temperature chemistry
+is more fuel-specific than high-temperature chemistry. This paper proposes a
+machine learning approach to learn the HyChem models that can cover both
+high-temperature and low-temperature regimes. Specifically, we develop a HyChem
+model using the experimental datasets of ignition delay times covering a wide
+range of temperatures and equivalence ratios. The chemical kinetic model is
+treated as a neural network model, and we then employ stochastic gradient
+descent (SGD), a technique that was developed for deep learning, for the
+training. We demonstrate the approach in learning the HyChem model for F-24,
+which is a Jet-A derived fuel, and compare the results with previous work
+employing genetic algorithms. The results show that the SGD approach can
+achieve comparable model performance with genetic algorithms but the
+computational cost is reduced by 1000 times. In addition, with regularization
+in SGD, the SGD approach changes the kinetic parameters from their original
+values much less than genetic algorithm and is thus more likely to retrain
+mechanistic meanings. Finally, our approach is built upon open-source packages
+and can be applied to the development and optimization of chemical kinetic
+models for internal combustion engine simulations.",2104.07875v1
+2021-04-16,Near ambient pressure photoelectron spectro-microscopy: from gas-solid interface to operando devices,"Near Ambient Pressure Scanning Photoelectron Microscopy adds to the widely
+used photoemission spectroscopy and its chemically selective capability two key
+features: (i) the possibility to chemically analyse samples in a more realistic
+environmental, gas pressure condition, and (ii) the capability to investigate a
+system at the relevant spatial scale. To achieve these goals the approach
+developed at the ESCA Microscopy beamline at the Elettra Synchrotron facility
+combines the submicron lateral resolution of a Scanning Photoelectron
+Microscope with a custom designed Near Ambient Pressure Cell where a gas
+pressure up to 0.1 mbar is confined inside it around the sample. In this
+manuscript a review of experiments performed with this unique setup will be
+presented to illustrate its potentiality in both fundamental and applicative
+research such as the oxidation reactivity and gas sensitivity of metal oxides
+and semiconductors. In particular the capability to do operando experiment with
+this setup opens the possibility to perform investigations with active devices
+to properly address the real nature of the studied systems, because it can
+yield to more conclusive results when microscopy and spectroscopy are
+simultaneously combined in a single technique.",2104.08090v1
+2021-04-30,Thermal transport evolution due to nanostructural transformations in Ga-doped indium-tin-oxide thin films,"We report on a comprehensive theoretical and experimental investigation of
+thermal conductivity in indium-tin-oxide (ITO) thin films with various Ga
+concentrations (0-30 at. %) deposited by spray pyrolysis technique. X-Ray
+diffraction (XRD) and scanning electron microscopy have shown a structural
+transformation in the range 15-20 at. % Ga from the nanocrystalline to the
+amorphous phase. Room temperature femtosecond time domain thermoreflectance
+measurements showed nonlinear decrease of thermal conductivity in the range
+2.0-0.5 W/(m K) depending on Ga doping level. Comparing density functional
+theory calculations with XRD data it was found that Ga atoms substitute In
+atoms in the ITO nanocrystals retaining Ia-3 space group symmetry. The
+calculated phonon dispersion relations revealed that Ga doping leads to the
+appearance of hybridized metal atom vibrations with avoided-crossing behavior.
+These hybridized vibrations possess shortened mean free paths and are the main
+reason behind the thermal conductivity drop in nanocrystalline phase. An
+evolution from propagative to diffusive phonon thermal transport in ITO:Ga with
+15-20 at. % of Ga was established. The suppressed thermal conductivity of
+ITO:Ga thin films deposited by spray pyrolysis may be crucial for their
+thermoelectric applications.",2105.00062v1
+2021-05-23,InAs nanocrystals with robust p-type doping,"Robust control over the carrier type is fundamental for the fabrication of
+nanocrystal-based optoelectronic devices, such as the p-n homojunction, but
+effective incorporation of impurities in semiconductor nanocrystals and its
+characterization is highly challenging due to their small size. Herein, InAs
+nanocrystals, post-synthetically doped with Cd, serve as a model system for
+successful p-type doping of originally n-type InAs nanocrystals, as
+demonstrated in field-effect transistors (FETs). Advanced structural analysis,
+using atomic resolution electron microscopy and synchrotron X-ray absorption
+fine structure spectroscopy reveal that Cd impurities reside near and on the
+nanocrystal surface acting as substitutional p-dopants replacing Indium.
+Commensurately, Cd-doped InAs FETs exhibited remarkable stability of their hole
+conduction, mobility, and hysteretic behavior over time when exposed to air,
+while intrinsic InAs NCs FETs were easily oxidized and their performance
+quickly declined. Therefore, Cd plays a dual role acting as a p-type dopant,
+and also protects the nanocrystals from oxidation, as evidenced directly by
+Xray photoelectron spectroscopy measurements of air-exposed samples of
+intrinsic and Cd doped InAs NCs films. This study demonstrates robust p-type
+doping of InAs nanocrystals, setting the stage for implementation of such doped
+nanocrystal systems in printed electronic devices.",2105.10881v1
+2021-06-04,Materials Representation and Transfer Learning for Multi-Property Prediction,"The adoption of machine learning in materials science has rapidly transformed
+materials property prediction. Hurdles limiting full capitalization of recent
+advancements in machine learning include the limited development of methods to
+learn the underlying interactions of multiple elements, as well as the
+relationships among multiple properties, to facilitate property prediction in
+new composition spaces. To address these issues, we introduce the Hierarchical
+Correlation Learning for Multi-property Prediction (H-CLMP) framework that
+seamlessly integrates (i) prediction using only a material's composition, (ii)
+learning and exploitation of correlations among target properties in
+multi-target regression, and (iii) leveraging training data from tangential
+domains via generative transfer learning. The model is demonstrated for
+prediction of spectral optical absorption of complex metal oxides spanning 69
+3-cation metal oxide composition spaces. H-CLMP accurately predicts non-linear
+composition-property relationships in composition spaces for which no training
+data is available, which broadens the purview of machine learning to the
+discovery of materials with exceptional properties. This achievement results
+from the principled integration of latent embedding learning, property
+correlation learning, generative transfer learning, and attention models. The
+best performance is obtained using H-CLMP with Transfer learning (H-CLMP(T))
+wherein a generative adversarial network is trained on computational density of
+states data and deployed in the target domain to augment prediction of optical
+absorption from composition. H-CLMP(T) aggregates multiple knowledge sources
+with a framework that is well-suited for multi-target regression across the
+physical sciences.",2106.02225v3
+2021-06-04,Requirements for beneficial electrochemical restructuring: A model study on a cobalt oxide in selected electrolytes,"The requirements for beneficial materials restructuring into a higher
+performance OER electrocatalyst are still a largely open question. Here we use
+Erythrite (Co$_3$(AsO$_4$)$_2\cdot$8H$_2$O) as a Co-based OER electrocatalyst
+to evaluate its catalytic properties during in-situ restructuring into an
+amorphous Co-based catalyst in four different electrolytes at pH 7. Using
+diffraction, microscopy and spectroscopy, we observed a strong effect in the
+restructuring kinetics depending of the anions in the electrolyte. Only
+carbonate electrolyte could activate the catalyst electrode, which we relate to
+its slow restructuring kinetics. While its turnover frequency (TOF) reduced
+from 2.84 O$_2$ Co$^{-1}$ s$^{-1}$ to a constant value of 0.10 O$_2$ Co$^{-1}$
+s$^{-1}$ after 300 cycles, the number of redox active sites continuously
+increased, which explained the current increase of around 100%. The final
+activated material owns an adequate local order, a high Co oxidation state and
+a high number of redox-active Co ions, which we identify as the trinity for
+enhancing the OER activity. Thus, this work provides new insights into for the
+rational design of high-performance OER catalysts by electrochemical
+restructuring.",2106.02362v1
+2021-06-18,Complementary junction field-effect transistor logic gate operational at 300$^\circ$C with 1.4 V supply voltage,"Integrated circuits (ICs) that can operate at high temperature have a wide
+variety of applications in the fields of automotive, aerospace, space
+exploration, and deep-well drilling. Conventional silicon-based complementary
+metal-oxide-semiconductor (CMOS) circuits cannot work at higher than 200
+$^\circ$C, leading to the use of wide bandgap semiconductor, especially silicon
+carbide (SiC). However, high-density defects at an oxide-SiC interface make it
+impossible to predict electrical characteristics of SiC CMOS logic gates in a
+wide temperature range and high supply voltage (typically ${\geqq 15}$ V) is
+required to compensate their large logic threshold voltage shift. Here, we show
+that SiC complementary logic gates composed of p- and n-channel junction
+field-effect transistors (JFETs) operate at 300 $^\circ$C with a supply voltage
+as low as 1.4 V. The logic threshold voltage shift of the complementary JFET
+(CJFET) inverter is 0.2 V from room temperature to 300 $^\circ$C. Furthermore,
+temperature dependencies of the static and dynamic characteristics of the CJFET
+inverter are well explained by a simple analytical model of SiC JFETs. This
+allows us to perform electronic circuit simulation, leading to superior
+designability of complex circuits or memories based on SiC CJFET technology,
+which operate within a wide temperature range.",2106.09902v1
+2021-07-02,Model of the Weak Reset Process in HfOx Resistive Memory for Deep Learning Frameworks,"The implementation of current deep learning training algorithms is
+power-hungry, owing to data transfer between memory and logic units.
+Oxide-based RRAMs are outstanding candidates to implement in-memory computing,
+which is less power-intensive. Their weak RESET regime, is particularly
+attractive for learning, as it allows tuning the resistance of the devices with
+remarkable endurance. However, the resistive change behavior in this regime
+suffers many fluctuations and is particularly challenging to model, especially
+in a way compatible with tools used for simulating deep learning. In this work,
+we present a model of the weak RESET process in hafnium oxide RRAM and
+integrate this model within the PyTorch deep learning framework. Validated on
+experiments on a hybrid CMOS/RRAM technology, our model reproduces both the
+noisy progressive behavior and the device-to-device (D2D) variability. We use
+this tool to train Binarized Neural Networks for the MNIST handwritten digit
+recognition task and the CIFAR-10 object classification task. We simulate our
+model with and without various aspects of device imperfections to understand
+their impact on the training process and identify that the D2D variability is
+the most detrimental aspect. The framework can be used in the same manner for
+other types of memories to identify the device imperfections that cause the
+most degradation, which can, in turn, be used to optimize the devices to reduce
+the impact of these imperfections.",2107.06064v2
+2021-07-19,"Low-energy consumption, free-form capacitive deionisation through nanostructured networks","Capacitive Deionization (CDI) is a non-energy intensive water treatment
+technology. To harness the enormous potential of CDI requires improving
+performance, while offering industrially feasible solutions. Following this
+idea, the replacement of costly metallic components has been proposed as a mean
+of limiting corrosion problems. This work explores the use of nanostructured
+hybrid networks to enable free-form and metal-free CDI devices. The strategy
+consists of producing interpenetrated networks of highly conductive flexible
+carbon nanotube (CNT) fibre fabrics and nanostructured metal oxides,
+{\gamma}Al2O3 and TiO2, through ultrasound-assisted nanoparticle infiltration
+and sintering. In the resulting hybrids, a uniform distribution of porous metal
+oxide is firmly attached to the nanocarbon network while the flexibility, high
+conductivity and low-dimensional properties of the CNTs are preserved. These
+electrodes present a high porosity ($105 - 118 m^{2} g^{1}$), notably low
+electrical ($< 0,1 k \Omega cm^{2}$) and low charge transfer resistance (4
+{\Omega}), thus enabling the infiltration of aqueous electrolytes and serving
+as current collector. In this work we built a large asymmetrical cylindrical
+CDI device solely made of these electrodes and conventional plastics. The cell
+provides, high average salt adsorption rates of $1.16 mg /g_{AM} min$ ($0.23
+mg/g_{CDIunit} min$, low energy consumption ($0.18 Wh/g_{salt}$) and stable
+electrochemical performance above 50 cycles for brackish water desalination.",2107.08867v1
+2021-07-30,Design of microring resonators integrated with 2D graphene oxide films for four-wave mixing,"We theoretically investigate and optimize the performance of four-wave mixing
+(FWM) in microring resonators (MRRs) integrated with two-dimensional (2D)
+layered graphene oxide (GO) films. Owing to the interaction between the MRRs
+and the highly nonlinear GO films as well as to the resonant enhancement
+effect, the FWM efficiency in GO-coated MRRs can be significantly improved.
+Based on previous experiments, we perform detailed analysis for the influence
+of the GO film parameters and MRR coupling strength on the FWM conversion
+efficiency (CE) of the hybrid MRRs. By optimizing the device parameters to
+balance the trade-off between the Kerr nonlinearity and loss, we achieve a high
+CE enhancement of ~18.6 dB relative to the uncoated MRR, which is ~8.3 dB
+higher than previous experimental results. The influence of photo-thermal
+changes in the GO films as well as variations in the MRR parameters such as the
+ring radius and waveguide dispersion on the FWM performance is also discussed.
+These results highlight the significantly improved FWM performance that can be
+achieved in MRRs incorporating GO films and provide a guide for optimizing
+their FWM performance.",2108.00110v1
+2021-08-12,Structure-selective operando x-ray spectroscopy,"The relationship between charge and structure dictates the properties of
+electrochemical systems. For example, reversible Na-ion intercalation - a
+low-cost alternative to Li-ion technology - often induces detrimental
+structural phase transformations coupled with charge compensation reactions.
+However, little is known about the underpinning charge-structure mechanisms
+because the reduction-oxidation (redox) reactions within coexisting structural
+phases have so far eluded direct operando investigation. Here, we distinguish
+x-ray spectra of individual crystalline phases operando during a redox-induced
+phase transformation in P2-Na2/3Ni1/3Mn2/3O2 - an archetypal layered oxide for
+sodium-ion batteries. We measure the resonant elastic scattering on the Bragg
+reflection corresponding to the P2-phase lattice spacing. These resonant
+spectra become static midway through the sodium extraction in an operando coin
+cell, while the overall sodium extraction proceeds as evidenced by the X-ray
+absorption averaging over all electrochemically active Ni atoms. The stop of
+redox activity in the P2-structure signifies its inability to host Ni4+ ions.
+The coincident emergence of the O2- structure reveals the rigid link between
+the local redox and the long-range order during the phase transformation. The
+structure-selective x-ray spectroscopy thus opens a powerful avenue for
+resolving the dynamic chemistry of different structural phases in multi-phase
+electrochemical systems.",2108.05913v1
+2021-08-18,High Entropy Alloy CrFeNiCoCu sputtered films,"High entropy alloy(HEA) films of CrFeCoNiCu were prepared by sputtering,
+their structure was characterized, and their electric properties measured by
+temperature dependent Hall and Seebeck measurement. The HEA films show a solid
+solution with fcc structure, and a 111 texture with columnar grains of widths
+15-30 nm extending through film thickness with very many twins. The residual
+electrical resistivity of the films is around 140 {\mu}{\Omega}cm and the
+temperature dependence of the resistivity is metal-like. The temperature
+coefficient of resistivity (TCR) is small (2 ppm/K). The Hall coefficient is
+positive while the Seebeck coefficients is negative. This is interpreted as
+arising from an electronic structure where the Fermi level passes through band
+states having both holes and electrons as indicated by band structure
+calculations. The HEA structure appears stable for annealing in vacuum, while
+annealing in an oxygen containing atmosphere causes the surface to oxidize and
+grow a Cr-rich oxide on the surface. This is then accompanied by demixing of
+the HEA solid solution and a decrease in residual resistance of the film.",2108.08373v2
+2021-08-18,Correlated Oxide Dirac Semimetal in the Extreme Quantum Limit,"Quantum materials (QMs) with strong correlation and non-trivial topology are
+indispensable to next-generation information and computing technologies.
+Exploitation of topological band structure is an ideal starting point to
+realize correlated topological QMs. Herein, we report that strain-induced
+symmetry modification in correlated oxide SrNbO3 thin films creates an emerging
+topological band structure. Dirac electrons in strained SrNbO3 films reveal
+ultra-high mobility (100,000 cm2/Vs), exceptionally small effective mass
+(0.04me), and non-zero Berry phase. More importantly, strained SrNbO3 films
+reach the extreme quantum limit, exhibiting a sign of fractional occupation of
+Landau levels and giant mass enhancement. Our results suggest that
+symmetry-modified SrNbO3 is a rare example of a correlated topological QM, in
+which strong correlation of Dirac electrons leads to the realization of
+fractional occupation of Landau levels.",2108.08408v1
+2021-08-19,Drift in a Popular Metal Oxide Sensor Dataset Reveals Limitations for Gas Classification Benchmarks,"Metal oxide (MOx) electro-chemical gas sensors are a sensible choice for many
+applications, due to their tunable sensitivity, their space-efficiency and
+their low price. Publicly available sensor datasets streamline the development
+and evaluation of novel algorithm and circuit designs, making them particularly
+valuable for the Artificial Olfaction / Mobile Robot Olfaction community. In
+2013, Vergara et al. published a dataset comprising 16 months of recordings
+from a large MOx gas sensor array in a wind tunnel, which has since become a
+standard benchmark in the field. Here we report a previously undetected
+property of the dataset that limits its suitability for gas classification
+studies. The analysis of individual measurement timestamps reveals that gases
+were recorded in temporally clustered batches. The consequential correlation
+between the sensor response before gas exposure and the time of recording is
+often sufficient to predict the gas used in a given trial. Even if compensated
+by zero-offset-subtraction, residual short-term drift contains enough
+information for gas classification. We have identified a minimally
+drift-affected subset of the data, which is suitable for gas classification
+benchmarking after zero-offset-subtraction, although gas classification
+performance was substantially lower than for the full dataset. We conclude that
+previous studies conducted with this dataset very likely overestimate the
+accuracy of gas classification results. For the 17 potentially affected
+publications, we urge the authors to re-evaluate the results in light of our
+findings. Our observations emphasize the need to thoroughly document gas
+sensing datasets, and proper validation before using them for the development
+of algorithms.",2108.08793v1
+2021-08-24,Dynamic Properties of Water inside Graphene Oxide Membranes,"Separation of salt ions from seawater using graphene oxide (GO) membrane is
+an emerging desalination method. Here, we investigate the dynamic behavior of
+water, sodium, and chloride ions inside GO membrane using a computational
+approach. First, we developed four different models of GO membrane with
+different distances between GO sheets (0.7, 0.9, 1.1, and 1.3 nm), and
+performed molecular dynamics (MD) simulations of water inside each membrane for
+20 ns. With the analysis of the mean squared displacement of water and the
+Einstein relation equation for diffusion, we measured the diffusion coefficient
+of water in each membrane. We found that the diffusion coefficient of water
+inside the GO membrane decreased as the distance between sheets (d) decreased.
+The measured diffusion coefficients (in unit of 0.00001 (cm*cm)/sec) of water
+are 0.03 (d = 0.7 nm), 0.91 (d = 0.9 nm), 1.18 (d = 1.1 nm), and 1.49 (d = 1.3
+nm), whereas it is 2.49 for bulk water. Second, for analyzing the desalination
+performance of each membrane, we also calculated the free energy profile of
+penetration of water, sodium, and chloride ions via the interlayer of the
+membrane. The free energy profile of penetration revealed that the optimum
+interlayer distance between GO sheets for desalination is 0.9 ~ 1.1 nm. With
+0.9 and 1.1 nm interlayer distance between GO sheets, the free energy barrier
+of membrane penetration of water is negligible, where it is 2 ~ 4 kcal/mol for
+sodium or chloride ions. We believe that our simulation results would be a
+significant contribution to designing a new GO-based membrane for desalination.",2108.10836v1
+2021-08-25,Measurement of Hybrid Rocket Solid Fuel Regression Rate for a Slab Burner using Deep Learning,"This study presents an imaging-based deep learning tool to measure the fuel
+regression rate in a 2D slab burner experiment for hybrid rocket fuels. The
+slab burner experiment is designed to verify mechanistic models of reacting
+boundary layer combustion in hybrid rockets by the measurement of fuel
+regression rates. A DSLR camera with a high intensity flash is used to capture
+images throughout the burn and the images are then used to find the fuel
+boundary to calculate the regression rate. A U-net convolutional neural network
+architecture is explored to segment the fuel from the experimental images. A
+Monte-Carlo Dropout process is used to quantify the regression rate uncertainty
+produced from the network. The U-net computed regression rates are compared
+with values from other techniques from literature and show error less than 10%.
+An oxidizer flux dependency study is performed and shows the U-net predictions
+of regression rates are accurate and independent of the oxidizer flux, when the
+images in the training set are not over-saturated. Training with monochrome
+images is explored and is not successful at predicting the fuel regression rate
+from images with high noise. The network is superior at filtering out noise
+introduced by soot, pitting, and wax deposition on the chamber glass as well as
+the flame when compared to traditional image processing techniques, such as
+threshold binary conversion and spatial filtering. U-net consistently provides
+low error image segmentations to allow accurate computation of the regression
+rate of the fuel.",2108.11276v1
+2021-08-25,A Stable High-Capacity Lithium-Ion Battery Using a Biomass-Derived Sulfur-Carbon Cathode and Lithiated Silicon Anode,"A full lithium-ion-sulfur cell with a remarkable cycle life was achieved by
+combining an environmentally sustainable biomass-derived sulfur-carbon cathode
+and a pre-lithiated silicon oxide anode. X-ray diffraction, Raman spectroscopy,
+energy dispersive spectroscopy, and thermogravimetry of the cathode evidenced
+the disordered nature of the carbon matrix in which sulfur was uniformly
+distributed with a weight content as high as 75%, while scanning and
+transmission electron microscopy revealed the micrometric morphology of the
+composite. The sulfur-carbon electrode in the lithium half-cell exhibited a
+maximum capacity higher than 1200 mAhgS-1, reversible electrochemical process,
+limited electrode/electrolyte interphase resistance, and a rate capability up
+to C/2. The material showed a capacity decay of about 40% with respect to the
+steady-state value over 100 cycles, likely due to the reaction with the lithium
+metal of dissolved polysulfides or impurities including P detected in the
+carbon precursor. Therefore, the replacement of the lithium metal with a less
+challenging anode was suggested, and the sulfur-carbon composite was
+subsequently investigated in the full lithium-ion-sulfur battery employing a
+Li-alloying silicon oxide anode. The full-cell revealed an initial capacity as
+high as 1200 mAhgS-1, a retention increased to more than 79% for 100
+galvanostatic cycles, and 56% over 500 cycles. The data reported herein well
+indicated the reliability of energy storage devices with extended cycle life
+employing high-energy, green, and safe electrode materials.",2108.11284v1
+2021-08-25,Degradation of Layered Oxide Cathode in a Sodium Battery: A Detailed Investigation by X-Ray Tomography at the Nanoscale,"The degradation mechanism in a sodium cell of a layered
+Na0.48Al0.03Co0.18Ni0.18Mn0.47O2 (NCAM) cathode with P3/P2 structure is
+investigated by revealing the changes in microstructure and composition upon
+cycling. The work aims to rationalize the gradual performance decay and the
+alteration of the electrochemical response in terms of polarization, voltage
+signature, and capacity loss. Spatial reconstructions of the electrode by X-ray
+computed tomography at the nanoscale supported by quantitative and qualitative
+analyses show fractures and deformations in the cycled layered metal-oxide
+particles, as well as inorganic side compounds deposited on the material. These
+irreversible morphological modifications reflect structural heterogeneities
+across the cathode particles due to formation of various domains with different
+Na+ intercalation degrees. Besides, X-ray photoelectron spectroscopy data
+suggest that the latter inorganic species in the cycled electrode are mainly
+composed of NaF, Na2O, and NaCO3 formed by parasitic electrolyte decomposition.
+The precipitation of these insulating compounds at the electrode/electrolyte
+interphase and the related structural stresses induced in the material lead to
+a decrease in cathode particle size and partial loss of electrochemical
+activity. The retention of the NCAM phase after cycling suggests that
+electrolyte upgrade may improve the performance of the cathode to achieve
+practical application for sustainable energy storage.",2108.11442v1
+2021-09-14,Photo-memristive sensing with charge storing 2D carbon nitrides,"We report the charge storing 2D carbon nitride potassium poly(heptazine
+imide), K-PHI, as a direct memristive (bio)sensing platform. Memristive devices
+have the potential to innovate current (bio)electronic systems such as
+photo-electrochemical sensors by incorporating new sensing capabilities
+including non-invasive, wireless remote and time-delayed (memory) readout. We
+demonstrate a direct photomemristive sensing platform that capitalizes on K
+PHI's visible light bandgap, large oxidation potential and intrinsic optoionic
+light energy storage properties. Our system simultaneously enables analyte
+concentration information storage as well as potentiometric, impedimetric and
+coulo-metric readouts on the same material, with no additional reagents
+required. Utilizing the light-induced charge storage function of K-PHI, we
+demonstrate analyte sensing via charge accumulation and present various methods
+to write/erase this information from the material. Additionally, fully wireless
+colorimetric and fluorometric detection of the charged state of K-PHI is
+demonstrated and could facilitate its use as particle-based in-situ sensing
+probe. The various readout options of the K PHI's response enable us to adapt
+the sensitivities and dynamic ranges without modifying the sensor. We
+demonstrate these features using glucose as an example analyte over a wide
+range of concentrations (50 $\mu$M to 50 mM). Moreover, due to the strong
+oxidative power of K-PHI, this sensing platform is able to detect a large
+variety of organic or biologically relevant analytes. Since PHI is easily
+synthesized, based on earth abundant precursors, biocompatible, chemically
+robust and responsive to visible light, we anticipate that the sensing platform
+presented herein opens up novel memristive and neuromorphic functions.",2109.06964v1
+2021-09-11,Design and characterization of effective solar cells,"We propose a two-stage multi-objective optimization framework for full scheme
+solar cell structure design and characterization, cost minimization and quantum
+efficiency maximization. We evaluated structures of 15 different cell designs
+simulated by varying material types and photodiode doping strategies. At first,
+non-dominated sorting genetic algorithm~II (NSGA-II) produced
+Pareto-optimal-solutions sets for respective cell designs. Then, on
+investigating quantum efficiencies of all cell designs produced by NSGA-II, we
+applied a new multi-objective optimization algorithm~II (OptIA-II) to discover
+the Pareto fronts of select (three) best cell designs. Our designed OptIA-II
+algorithm improved the quantum efficiencies of all select cell designs and
+reduced their fabrication costs. We observed that the cell design comprising an
+optimally doped zinc-oxide-based transparent conductive oxide (TCO) layer and
+rough silver back reflector (BR) offered a quantum efficiency ($Q_e$) of
+$0.6031.$ Overall, this paper provides a full characterization of cell
+structure designs. It derives a relationship between quantum efficiency, $Q_e$
+of a cell with its TCO layer's doping methods and TCO and BR layer's material
+types. Our solar cells design characterization enables us to perform a
+cost-benefit analysis of solar cells usage in real-world applications",2109.07279v1
+2021-09-20,Microwave-optical coupling via Rydberg excitons in cuprous oxide,"We report exciton-mediated coupling between microwave and optical fields in
+cuprous oxide (Cu$_2$O) at low temperatures. Rydberg excitonic states with
+principal quantum number up to $n=12$ were observed at 4~K using both
+one-photon (absorption) and two-photon (second harmonic generation)
+spectroscopy. Near resonance with an excitonic state, the addition of a
+microwave field significantly changed the absorption lineshape, and added
+sidebands at the microwave frequency to the coherent second harmonic. Both
+effects showed a complex dependence on $n$ and angular momentum, $l$. All of
+these features are in semi-quantitative agreement with a model based on
+intraband electric dipole transitions between Rydberg exciton states. With a
+simple microwave antenna we already reach a regime where the microwave coupling
+(Rabi frequency) is comparable to the nonradiatively broadened linewidth of the
+Rydberg excitons. The results provide a new way to manipulate excitonic states,
+and open up the possibility of a cryogenic microwave to optical transducer
+based on Rydberg excitons.",2109.09614v2
+2021-09-28,Remarkably Enhanced Dynamic Oxygen Migration on Graphene Oxide Supported by Copper Substrate,"The dynamic covalent properties of graphene oxide (GO) are of fundamental
+interest to a broad range of scientific areas and technological applications.
+It remains a challenge to access the feasible dynamic reactions for reversibly
+breaking/reforming covalent bonds of oxygen functional groups on GO, although
+these reactions can be induced by photonic or mechanical routes, or mediated by
+adsorbed water. Here, using the density functional theory calculations, we
+demonstrate the remarkably enhanced dynamic oxygen migration along the basal
+plane of GO supported by copper substrate (GO@copper), with the C-O bond
+breaking reaction and proton transfer between the neighboring epoxy and
+hydroxyl groups. Compared to that on GO, the energy barrier of oxygen migration
+on GO@copper is sharply reduced to be less than or comparable to thermal
+fluctuations, and meanwhile the crystallographic match between GO and copper
+substrate induces new oxygen migration paths on GO@copper. This work sheds
+light on the understanding of metal substrate-enhanced dynamic properties of
+GO, and evidences the strategy to tune the activity of
+two-dimension-interfacial oxygen groups for various potential applications.",2109.13575v3
+2021-10-15,Effective reduction of biofilm through photothermal therapy by gold core@shell based mesoporous silica nanoparticles,"Bacterial biofilms can initiate chronic infections that become difficult to
+eradicate. There is an unmet need for effective therapeutic strategies that
+control and inhibit the growth of these biofilms. Herein, light sensitive
+mesoporous silica nanoparticles (MSNs) with photothermal (PTT) and
+antimicrobial combined capabilities have been developed. These nanosystems have
+high therapeutic potential to affect the bacterial biofilm architecture and
+subsequently inhibit its growth. Nucleation of gold nanorods followed by the
+growth of a silica shell leads to a core@shell design (AuNR@MSN) with PTT
+properties. Incorporation of nitrosothiol groups (-SNO) with a heat liable
+linker, enables an enhanced nitric oxide release upon photothermal stimulation
+with near infrared radiation. Further loading of an antimicrobial molecule such
+as the levofloxacin (LEVO) antibiotic creates a unique nanoassembly with
+potential therapeutic efficacy against Staphylococcus aureus bacterial
+biofilms. A dispersion rate of the bacterial biofilm was evident when light
+stimuli is applied because impregnation of the nitrosothiol functionalized
+nanosystem with the antibiotic LEVO led to ca. 30% reduction but its
+illumination with near infrared (NIR) irradiation showed a biofilm reduction of
+ca. 90%, indicating that localized antimicrobial exposure and PTT improves the
+therapeutic efficacy. These findings envision the conception of
+near-infraredactivated nanoparticle carriers capable of combined therapy upon
+NIR irradiation, which enables photothermal therapy, together with the release
+of levofloxacin and nitric oxide to disrupt the integrity of bacterial biofilms
+and achieve a potent antimicrobial therapy.",2110.07924v1
+2021-10-23,Numerous chondritic impactors and oxidized magma ocean set Earth's volatile depletion,"Earth's surface environment is largely influenced by its budget of major
+volatile elements: carbon (C), nitrogen (N), and hydrogen (H). Although the
+volatiles on Earth are thought to have been delivered by chondritic materials,
+the elemental composition of the bulk silicate Earth (BSE) shows depletion in
+the order of N, C, and H. Previous studies have concluded that non-chondritic
+materials are needed for this depletion pattern. Here, we model the evolution
+of the volatile abundances in the atmosphere, oceans, crust, mantle, and core
+through the accretion history by considering elemental partitioning and impact
+erosion. We show that the BSE depletion pattern can be reproduced from
+continuous accretion of chondritic bodies by the partitioning of C into the
+core and H storage in the magma ocean in the main accretion stage and
+atmospheric erosion of N in the late accretion stage. This scenario requires a
+relatively oxidized magma ocean ($\log_{10} f_{\rm O_2}$ $\gtrsim$
+$\rm{IW}$$-2$, where $f_{\rm O_2}$ is the oxygen fugacity, ${\rm IW}$ is
+$\log_{10} f_{\rm O_2}^{\rm IW}$, and $f_{\rm O_2}^{\rm IW}$ is $f_{\rm O_2}$
+at the iron-w\""{u}stite buffer), the dominance of small impactors in the late
+accretion, and the storage of H and C in oceanic water and carbonates in the
+late accretion stage, all of which are naturally expected from the formation of
+an Earth-sized planet in the habitable zone.",2110.12195v1
+2021-10-23,Zinc Oxide-Based Piezoelectric Pressure Sensor,"This paper reports the application of zinc oxide (ZnO) in the pressure
+sensors that can be integrated with a microelectromechanical system (MEMS). ZnO
+is one of the materials that has received a great deal of attention due to its
+unique properties of being a semiconductor with wide bandgap and piezoelectric
+effects. The simpler crystal growth mechanisms of ZnO have resulted in a lower
+cost of ZnO-based sensors. Different types of pressure sensors based on ZnO
+sensing elements have also been explored. A thin circular ZnO film was
+simulated as a piezoelectric sensor employing the finite element method in
+COMSOL. The pressure applied on the thin film surface was varied and a boundary
+point probe was used to study the displacement field and voltage at the center
+of the membrane. The displacement field and voltage induced by pressure vary
+linearly with increasing pressure on the ZnO layer. Also. the method used in
+this paper was applied to different piezoelectric materials, such as barium
+titanate (BaTiO3), polyvinylidene fluoride (PVDF), and gallium arsenide (GaAs)
+that were studied by other groups, and similar conclusions were made. These
+simulations can be used in the design of piezoelectric sensors and the
+optimization of the sensitivity and performance of the materials used in
+pressure sensor applications.",2110.13643v1
+2021-11-01,Pressure-induced metal-insulator transition in oxygen-deficient LiNbO$_3$-type ferroelectrics,"Hydrostatic pressure and oxygen vacancies usually have deleterious effects on
+ferroelectric materials because both tend to reduce their polarization. In this
+work we use first-principles calculations to study an important class of
+ferroelectric materials - LiNbO$_3$-type ferroelectrics (LiNbO$_3$ as the
+prototype), and find that in oxygen-deficient LiNbO$_{3-\delta}$, hydrostatic
+pressure induces an unexpected metal-insulator transition between 8 and 9 GPa.
+Our calculations also find that strong polar displacements persist in both
+metallic and insulating oxygen-deficient LiNbO$_{3-\delta}$ and the size of
+polar displacements is comparable to pristine LiNbO$_3$ under the same
+pressure. These properties are distinct from widely used perovskite
+ferroelectric oxide BaTiO$_3$, whose polarization is quickly suppressed by
+hydrostatic pressure and/or oxygen vacancies. The anomalous pressure-driven
+metal-insulator transition in oxygen-deficient LiNbO$_{3-\delta}$ arises from
+the change of an oxygen vacancy defect state. Hydrostatic pressure increases
+the polar displacements of oxygen-deficient LiNbO$_{3-\delta}$, which reduces
+the band width of the defect state and eventually turns it into an in-gap
+state. In the insulating phase, the in-gap state is further pushed away from
+the conduction band edge under hydrostatic pressure, which increases the
+fundamental gap. Our work shows that for LiNbO$_3$-type strong ferroelectrics,
+oxygen vacancies and hydrostatic pressure combined can lead to new phenomena
+and potential functions, in contrast to the harmful effects occurring to
+perovskite ferroelectric oxides such as BaTiO$_3$.",2111.00911v1
+2021-11-05,Surface plasmons on a Au waveguide electrode open new redox channels associated with the transfer of energetic carriers,"Plasmonic catalysis holds significant promise for opening new reaction
+pathways inaccessible thermally, or for improving the efficiency of chemical
+processes. However, challenges persist in distinguishing photothermal effects
+from effects due to energetic electrons and/or holes excited in the metal
+comprising a plasmonic structure. Here we use a Au stripe waveguide along which
+surface plasmon polaritons (SPPs) propagate, operating simultaneously as a
+working electrode in a 3-electrode electrochemical cell. Cyclic voltammograms
+were obtained under SPP excitation as a function of incident optical power and
+wavelength ~ 1350 nm, enabling processes involving energetic holes to be
+separated from processes involving energetic electrons by investigating
+oxidation and reduction reactions separately. Redox current densities increase
+by 10x under SPP excitation. The oxidation, reduction and equilibrium
+potentials drop by as much as 2x and split beyond a clear threshold with SPP
+power in correlation with the photon energy. The temperature of the working
+electrode under SPP excitation is monitored in situ and independent control
+experiments isolate thermal effects. Chronoamperometry measurements with on-off
+modulated SPPs at 600 Hz, yield a diffusion-limited rapid current response
+modulated at the same frequency, ruling out thermally-enhanced mass transport.
+Our observations are attributed to the opening of optically controlled
+non-equilibrium redox channels associated with energetic carrier transfer to
+the redox species.",2111.03681v1
+2021-10-25,Modeling of Graphene Oxide Memory based on Hybridization State Modulation,"Graphene oxide (GO)-based resistive random access memory (RRAM) is one of the
+most promising emerging non-volatile memories for flexible electronics because
+of its simple structure and low fabrication cost. The reported switching
+mechanism can be classified into either localized or bulk effect. The localized
+effect is commonly observed in GO-RRAM with active electrode e.g. Cu and Al.
+The switching mechanism includes metallic conduction filament evolution or
+modification of interfacial resistance between GO layer and electrodes. On the
+other hand, the bulk effect involves hybridization state change of the entire
+GO layer and is typically observed in devices with inert electrode e.g. Pt and
+Au. Numerous compact models have been proposed for RRAM that are based on
+localized switching mechanism. However, compact modeling of GO-RRAM based on
+bulk mechanism is still lacking. Thus, this paper presents a compact model for
+GO-RRAM that relies on hybridization state modulation. The proposed model
+associates the resistance switching mechanism with the electricaldriven
+modification of sp2 clusters density in the switching layer. A SPICE model
+incorporating the proposed compact model is developed for parameter
+calibration. The simulated I-V characteristic exhibits strong correlation with
+the experimental data. Hereby, we regard the proposed compact model as an
+acceptable and close description of GO-RRAM operation that depends on the bulk
+switching mechanism.",2111.04440v1
+2021-11-18,Searching for Superconductivity in High Entropy Oxide Ruddlesden-Popper Cuprate Films,"In this work, the high entropy oxide A2CuO4 Ruddlesden-Popper
+(La0.2Pr0.2Nd0.2Sm0.2Eu0.2)2CuO4 is explored by charge doping with Ce+4 and
+Sr+2 at concentrations known to induce superconductivity in the simple parent
+compounds, Nd2CuO4 and La2CuO4. Electron doped
+(La0.185Pr0.185Nd0.185Sm0.185Eu0.185Ce0.075)2CuO4 and hole doped
+(La0.18Pr0.18Nd0.18Sm0.18Eu0.18Sr0.1)2CuO4 are synthesized and shown to be
+single crystal, epitaxially strained, and highly uniform. Transport
+measurements demonstrate that all as-grown films are insulating regardless of
+doping. Annealing studies show that resistivity can be tuned by modifying
+oxygen stoichiometry and inducing metallicity but without superconductivity.
+These results in turn are connected to extended x-ray absorption fine structure
+(EXAFS) results indicating that the lack of superconductivity in the high
+entropy cuprates likely originates from a large distortion within the Cu-O
+plane ({\sigma}2>0.015 {\AA}2) due to A-site cation size variance, which drives
+localization of charge carriers. These findings describe new opportunities for
+controlling charge- and orbital-mediated functional responses in
+Ruddlesden-Popper crystal structures, driven by balancing of cation size and
+charge variances that may be exploited for functionally important behaviors
+such as superconductivity, antiferromagnetism, and metal-insulator transitions,
+while opening less understood phase spaces hosting doped Mott insulators,
+strange metals, quantum criticality, pseudogaps, and ordered charge density
+waves.",2111.09767v1
+2021-12-03,Mid-infrared Fourier-transform spectrometer based on metamaterial lateral cladding suspended silicon waveguides,"Integrated mid-infrared micro-spectrometers have a great potential for
+applications in environmental monitoring and space exploration.
+Silicon-on-insulator (SOI) is a promising platform to tackle this integration
+challenge, due to its unique capability for large volume and low-cost
+production of ultra-compact photonic circuits. However, the use of SOI in the
+mid-infrared is restricted by the strong absorption of the buried oxide layer
+for wavelengths beyond 4 {\mu}m. Here, we overcome this limitation by utilizing
+metamaterial-cladded suspended silicon waveguides to implement a spatial
+heterodyne Fourier-transform (SHFT) spectrometer operating near 5.5{\mu}m
+wavelength. The metamaterial-cladded geometry allows removal of the buried
+oxide layer, yielding measured propagation loss below 2 dB/cm between 5.3{\mu}m
+and 5.7{\mu}m wavelengths. The SHFT spectrometer comprises 19 Mach-Zehnder
+interferometers with a maximum arm length imbalance of 200 {\mu}m, achieving a
+measured spectral resolution of 13cm-1 and a free-spectral range of 100 cm-1
+near 5.5{\mu}m wavelength.",2112.01961v1
+2021-12-06,X-ray characterization of BUSARD chip: A HV-SOI monolithic particle detector with pixel sensors under the buried oxide,"This work presents the design of BUSARD, an application specific integrated
+circuit (ASIC) for the detection of ionizing particles. The ASIC is a
+monolithic active pixel sensor which has been fabricated in a High-Voltage
+Silicon-On-Insulator (HV-SOI) process that allows the fabrication of a buried
+N+ diffusion below the Buried OXide (BOX) as a standard processing step. The
+first version of the chip, BUSARD-A, takes advantage of this buried diffusion
+as an ionizing particle sensor. It includes a small array of 13$\times$13
+pixels, with a pitch of $80\,\mu$m, and each pixel has one buried diffusion
+with a charge amplifier, discriminator with offset tuning and digital
+processing. The detector has several operation modes including particle
+counting and Time-over-Threshold (ToT). An initial X-ray characterization of
+the detector was carried out, obtaining several pulse height and ToT spectra,
+which then were used to perform the energy calibration of the device. The
+Molybdenum $\mathbf{K_{\alpha}}$ emission was measured with a standard
+deviation of $127\,e^{-}$ of ENC by using the analog pulse output, and with
+$276\,e^{-}$ of ENC by using the ToT digital output. The resolution in ToT mode
+is dominated by the pixel-to-pixel variation.",2112.03166v1
+2021-12-11,Hydrogen related defects in titanium dioxide at the interface to palladium,"A metal oxide support and a catalytically active metal are the two main
+ingredients for complex catalysts used in heterogeneous catalysis. The gas
+environment can change the catalyst during the reaction, modifying its
+structural and electronic properties. Here, we use monochromated electron
+energy loss spectroscopy (EELS) to reveal hydrogen-pressure-dependent changes
+of the electronic structure at the Pd/rutile-TiO$_2$ interface in an
+environmental transmission electron microscope (ETEM). Hydrogen-induced changes
+are observed in rutile-TiO$_2$ within $2$~nm from the interface at $10$~Pa of
+hydrogen pressure, in the Ti $L_{3,2}$ EEL spectra. Lower pressures such as
+$1$~Pa show no changes in the EEL spectra. We attribute the observed changes in
+the EEL spectra to hydrogen-induced defects accumulating in the vicinity of the
+interface. Based on DFT calculations, we developed a thermodynamic multistate
+defect (TMD) model of the interface and the bulk of the rutile-TiO$_2$. This
+TMD model predicts high concentrations of positively charged defects
+accumulating at the interface. The presence of the Schottky barrier stabilizes
+these defects by significantly lowering their formation energy. Our findings
+provide important new insights into catalytic processes taking place at
+metal/metal oxide interfaces in hydrogen gas environments.",2112.05953v1
+2021-12-15,All Inorganic p_n Heterojunction Solar Cells by Solution Combustion Synthesis using n_type FeMnO3 Perovskite Photoactive Layer,"This study outlines the synthesis and physicochemical characteristics of a
+solution-processable iron manganite (FeMnO3) nanoparticles via a chemical
+combustion method using tartartic acid as a fuel and demonstrates the
+performance of this material as a n-type photoactive layer in all-oxide solar
+cells. It is shown that the solution combustion synthesis (SCS) method enables
+the formation of pure crystal phase FeMnO3 with controllable particle size. XRD
+pattern and morphology images from TEM confirm the purity of FeMnO3 phase and
+the relative small crystallite size (~13 nm), firstly reported in the
+literature. Moreover, to assemble a network of connected FeMnO3 nanoparticles,
+\b{eta}-alanine was used as a capping agent and dimethylformamide (DMF) as a
+polar aprotic solvent for the colloidal dispersion of FeMnO3 NPs. This
+procedure yields a ~500 nm thick photoactive layer. The proposed method is
+crucial to obtain functional solution processed NiO/FeMnO3 heterojunction
+inorganic photovoltaics. The optoelectronic properties of the heterojunction
+were established. These solar cells demonstrate a high open circuit voltage of
+1.31 V with sufficient fill factor of 54.3% and low short circuit current of
+0.07 mA cm-2 delivering a power conversion efficiency of 0.05% under 100 mW
+cm-2 illumination. This work expands on the burgeoning of environmentally
+friendly, low-cost, sustainable solar cell material that derive from metal
+oxides.",2112.08057v1
+2021-12-16,Correct and accurate polymorphic energy ordering of transition-metal monoxides obtained from semilocal and onsite-hybrid exchange-correlation approximations,"The relative energetic stability of the structural phases of common
+antiferromagnetic transition-metal oxides (MnO, FeO, CoO, and NiO) within the
+semilocal and hybrid density functionals are fraught with difficulties. In
+particular, MnO is known to be the most difficult case for almost all common
+semilocal and hybrid density approximations. Here, we show that the
+meta-generalized gradient approximation (meta-GGA) constructed from the
+cuspless hydrogen model and Pauli kinetic energy density (MGGAC) can lead to
+the correct ground state of MnO. The relative energy differences of zinc-blende
+(zb) and rock-salt (rs) structures as computed using MGGAC are found to be in
+nice agreement with those obtained from high-level correlation methods like the
+random phase approximation or quantum Monte Carlo techniques. Besides, we have
+also applied the onsite hybrid functionals (closely related to DFT+U ) based on
+GGA and meta-GGA functionals, and it is shown that a relatively high amount of
+Hartree-Fock exchange is necessary to obtain the correct ground-state
+structure. Our present investigation suggests that the semilocal MGGAC and
+onsite hybrids, both being computationally cheap, as methods of choice for the
+calculation of the relative stability of antiferromagnetic transition-metal
+oxides having potential applications in solid-state physics and structural
+chemistry.",2112.09022v1
+2021-12-22,Self-repairing high entropy oxides,"All biological organisms, from plants to living creatures, can heal minor
+wounds and damage. The realization of a similar self-healing capacity in
+inorganic materials has been a design target for many decades. This would
+represent a breakthrough in materials engineering, enabling many novel
+technological applications, since such materials would be able to resist damage
+caused by electromagnetic irradiation and/or mechanical impact. Here we
+demonstrate that a high-entropy oxide is intrinsically capable of undergoing an
+autonomous self-repairing process. Transmission electron microscopy revealed
+that the spinel structure of (AlCoCrCu0.5FeNi)3O4 can regrow and repair itself
+at the atomic level when damaged. Density functional theory calculations reveal
+that the extra enthalpy stored in the high entropy material during fabrication
+can be released to effectively heal macroscopic defects by regrowing into a
+partially ordered state. This extraordinary self-repairing phenomenon makes
+this new material highly desirable as a coating, enabling structures used in
+harsh environments to better withstand damage, such as cosmic irradiation in
+space, nuclear irradiation in nuclear power facilities, or tribological damage.
+Most importantly, our results set the general design principles for the
+synthesis of self-repairing materials.",2112.11747v1
+2021-12-28,A $d^8$ anti-Hund's Singlet Insulator in an Infinite-layer Nickelate,"The status of nickelate superconductors in relation to cuprate high
+temperature superconductors is one of the concepts being discussed in high
+temperature superconductivity in correlated transition metal oxides. New
+additions to the class of infinite layer nickelates can provide essential input
+relating to connections or distinctions. A recently synthesized compound
+\bnoas, which contains isolated `infinite layer' NiO$_2$ planes, may lead to
+new insights. Our investigations have discovered that, at density functional
+theory mean field level, the ground state consists of an unusual $e_g$ singlet
+on the Ni$^{2+}$ ion arising from large but separate Mott insulating gaps in
+both $e_g$ orbitals, but with different, anti-Hund's, spin directions of their
+moments. This textured singlet incorporates at the least new physics, and
+potentially a new platform for nickelate superconductivity, which might be of
+an unconventional form for transition metal oxides due to the unconventional
+undoped state. We include in this paper a comparison of electronic structure
+parameters of Ba$_2$NiO$_2$(AgSe)$_2$ with a better characterized infinite
+layer nickelate LaNiO$_2$. We provide more analysis of the $d^8$ anti-Hund's
+singlet that emerges in this compound, and consider a minimally correlated
+wavefunction for this singlet in an itinerant background, and begin discussion
+of excitations -- real or virtual -- that may figure into new electronic
+phases.",2112.14010v2
+2021-12-31,21-Component Compositionally Complex Ceramics: Discovery of Ultrahigh-Entropy Weberite and Fergusonite Phases and a Pyrochlore-Weberite Transition,"Two new high-entropy ceramics (HECs) in the weberite and fergusonite
+structures, along with unexpected formation of ordered pyrochlore phases with
+ultrahigh-entropy compositions and an abrupt pyrochlore-weberite transition,
+are discovered in a 21-component oxide system. While the Gibbs phase rule
+allows 21 equilibrium phases, nine out of the 13 compositions examined possess
+single HEC phases (with ultrahigh ideal configurational entropies: ~2.7kB per
+cation or higher on one sublattice in most cases). Notably,
+(15RE1/15)(Nb1/2Ta1/2)O4 possess a single monoclinic fergusonite (C2/c) phase
+and (15RE1/15)3(Nb1/2Ta1/2)1O7 form a single orthorhombic (C2221) weberite
+phase, where 15RE1/15 represents
+Sc1/15Y1/15La1/15Pr1/15Nd1/15Sm1/15Eu1/15Gd1/15Tb1/15Dy1/15Ho1/15Er1/15Tm1/15Yb1/15Lu1/15.
+Moreover, a series of eight
+(15RE1/15)2+x(Ti1/4Zr1/4Ce1/4Hf1/4)2-2x(Nb1/2Ta1/2)xO7 specimens all exhibit
+single phases, where a pyrochlore-weberite transition occurs within 0.75 < x <
+0.8125. This cubic-to-orthorhombic transition does not change the
+temperature-dependent thermal conductivity appreciably, as the amorphous limit
+may have already been achieved in the ultrahigh-entropy 21-component oxides.
+These discoveries expand the diversity and complexity of HECs, towards
+many-component compositionally complex ceramics (CCCs) and ultrahigh-entropy
+ceramics.",2112.15381v2
+2021-12-31,Predicting the Oxidation States of Mn ions in the Oxygen Evolving Complex of Photosystem II Using Supervised and Unsupervised Machine Learning,"Serial Femtosecond Crystallography at the X-ray Free Electron Laser (XFEL)
+sources enabled the imaging of the catalytic intermediates of the oxygen
+evolution reaction of Photosystem II. However, due to the incoherent transition
+of the S-states, the resolved structures are a convolution from different
+catalytic states. Here, we train Decision Tree Classifier and K-mean clustering
+models on Mn compounds obtained from the Cambridge Crystallographic Database to
+predict the S-state of the X-ray, XFEL, and CryoEm structures by predicting the
+Mn's oxidation states in the oxygen evolving complex (OEC). The model agrees
+mostly with the XFEL structures in the dark S1 state. However, significant
+discrepancies are observed for the excited XFEL states (S2, S3, and S0) and the
+dark states of the X-ray and CryoEm structures. Furthermore, there is a
+mismatch between the predicted S-states within the two monomers of the same
+dimer, mainly in the excited states. The model suggests that improving the
+resolution is crucial to precisely resolve the geometry of the illuminated
+S-states to overcome the noncoherent S-state transition. In addition,
+significant radiation damage is observed in X-ray and CryoEM structures,
+particularly at the dangler Mn center (Mn4). Our model represents a valuable
+tool for investigating the electronic structure of the catalytic metal cluster
+of PSII to understand the water splitting mechanism.",2112.15460v2
+2022-01-02,Electrochemically-driven insulator-metal transition in ionic-liquid-gated antiferromagnetic Mott-insulating NiS$_2$ single crystals,"Motivated by the existence of superconductivity in pyrite-structure CuS$_2$,
+we explore the possibility of ionic-liquid-gating-induced superconductivity in
+the proximal antiferromagnetic Mott insulator NiS$_2$. A clear gating-induced
+transition from a two-dimensional insulating state to a three-dimensional
+metallic state is observed at positive gate bias on single crystal surfaces. No
+evidence for superconductivity is observed down to the lowest measured
+temperature of 0.45 K, however. Based on transport, energy-dispersive X-ray
+spectroscopy, X-ray photoelectron spectroscopy, atomic force microscopy, and
+other techniques, we deduce an electrochemical gating mechanism involving a
+substantial decrease in the S:Ni ratio (over hundreds of nm), which is both
+non-volatile and irreversible. This is in striking contrast to the reversible,
+volatile, surface-limited, electrostatic gate effect in pyrite FeS$_2$. We
+attribute this stark difference in electrochemical vs. electrostatic gating
+response in NiS$_2$ and FeS$_2$ to the much larger S diffusion coefficient in
+NiS$_2$, analogous to the different behaviors observed among electrolyte-gated
+oxides with differing O-vacancy diffusivities. The gating irreversibility, on
+the other hand, is associated with the lack of atmospheric S; this is in
+contrast to the better understood oxide case, where electrolysis of atmospheric
+H$_2$O provides an O reservoir. This study of NiS$_2$ thus provides new insight
+into electrolyte gating mechanisms in functional materials, in a previously
+unexplored limit.",2201.00340v1
+2021-12-28,Template-assisted growth of silver nanowires by electrodeposition,"Template-assisted synthesis is a facile way of growing various
+one-dimensional nanostructures. Among various nanoporous templates, anodic
+aluminium oxide (AAO) is most commonly used. In this work, the kinetics of
+silver nanowire growth by electrodeposition in AAO templates was investigated.
+The AAO templates were fabricated using the standard two-step anodisation
+process. The geometrical features of the fabricated templates, such as pore
+diameter (55 nm), interpore distance (115 nm), wall thickness (27 nm), porosity
+(19.87 %), and pore density were obtained using scanning electron microscopy.
+The oxide layer at the bottom of the pores was modified by the barrier layer
+thinning process and chemical etching in order to facilitate uniform metal
+deposition. This was followed by pore widening to increase the diameter of the
+pores to 65 nm to enhance deposition. Interpore distance increased to 119.8 nm
+and wall thickness remained almost constant at 27.7 nm. Silver was deposited
+using conventional electrodeposition in constant current mode. Deposition
+parameters such as time, current, solution concentration, and temperature were
+systematically investigated. For each deposition, the efficiency of the process
+was calculated by considering the filling fraction of the pores and the average
+length of the wires, all of which were measured from the SEM images. A linear
+growth versus time was observed within the parameter range. From the
+experiments, it was observed that decreasing the current, increasing the
+deposition temperature, and depositing for longer duration increased the
+average length of the nanowires. The use of electrodeposition to grow metallic
+nanowires can be extended to other pure metal and alloy systems.",2201.04947v2
+2022-01-12,Insights into cation ordering of double perovskite oxides from machine learning and causal relations,"This work investigates the origins of cation ordering of double perovskites
+using first-principles theory computations combined with machine learning (ML)
+and causal relations. We have considered various oxidation states of A, A', B,
+and B' from the family of transition metal ions to construct a diverse
+compositional space. A conventional framework employing traditional ML
+classification algorithms such as Random Forest (RF) coupled with appropriate
+features including geometry-driven and key structural modes leads to highly
+accurate prediction (~98%) of A-site cation ordering. We have evaluated the
+accuracy of ML models by entailing analyses of decision paths, assignments of
+probabilistic confidence bound, and finally introducing a direct non-Gaussian
+acyclic structural equation model to investigate causality. Our study suggests
+that the structural modes are the most important features for classifying
+layered, columnar and rock-salt ordering. For clear layered ordering, the
+charge difference between the A and A' is the most important feature which in
+turn depends on the B, B' charge separation. Based on the outputs from ML
+models, we have designed functional forms with these features to derive energy
+differences forming clear layered ordering. The trilinear coupling between
+tilt, rotation, and A-site antiferroelectric displacement in Landau free-energy
+expansion becomes the necessary condition behind the formation of A-site cation
+ordering.",2201.04970v2
+2022-01-17,Epitaxial stabilization of an orthorhombic Mg-Ti-O superconductor,"The family of titanium oxide superconductors exhibits many intriguing
+phenomena comparable to cuprates and iron pnictides/chalcogenides, and thus
+provides an ideal platform to contrastively study the unconventional pairing
+mechanism of high-temperature superconductors. Here, we successfully deposit
+superconducting Mg-Ti-O films on MgAl$_2$O$_4$ substrates with three principal
+orientations by ablating a MgTi$_2$O$_4$ target. Particularly, it is striking
+to observed that a single-crystalline film of an unintended structure has been
+grown on the (011)-oriented substrate, with the highest zero resistance
+transition temperature ($T_{\mathrm{c}0}$) of 5.0 K among them. The film has a
+highly reduced Mg/Ti ratio and an orthorhombic Ti$_9$O$_{10}$-like structure
+(denoted as Mg: Ti$_9$O$_{10}$), demonstrated by further characterizations of
+chemical composition and structure. Such a structure is unstable in bulk but
+favorable to be epitaxially stabilized on the (011)-surface of MgAl$_2$O$_4$
+due to a relatively small strain at the formed interface. An isotropic upper
+critical field ($B_{\mathrm{c}2}$) up to 13.7 T that breaks the Pauli limit is
+observed in the Mg: Ti$_9$O$_{10}$ film, analogous to other superconducting
+titanium oxides. The similarity points to a common origin for the
+superconductivity in the family, which will provide valuable opinions for the
+mechanism of unconventional superconductivity in transition metal compounds.",2201.06400v2
+2022-01-18,Zoology of spin and orbital fluctuations in ultrathin oxide films,"Many metallic transition-metal oxides turn insulating when grown as films
+that are only a few unit-cells thick. The microscopic origins of these
+thickness induced metal-to-insulator transitions however remain under dispute.
+Here, we simulate the extreme case of a monolayer of an inconspicuous
+correlated metal -- the strontium vanadate SrVO$_3$ -- deposited on a SrTiO$_3$
+substrate. Crucially, our system can have a termination to vacuum consisting of
+either a SrO or a VO$_2$ top layer. While we find that both lead to Mott
+insulating behavior at nominal stoichiometry, the phase diagram emerging upon
+doping -- chemically or through an applied gate voltage -- is qualitatively
+different. Indeed, our many-body calculations reveal a cornucopia of nonlocal
+fluctuations associated with (in)commensurate antiferromagnetic, ferromagnetic,
+as well as stripe and checkerboard orbital ordering instabilities. Identifying
+that the two geometries yield crystal-field splittings of opposite signs, we
+elucidate the ensuing phases through the lens of the orbital degrees of
+freedom. Quite generally, our work highlights that interface and surface
+reconstruction and the deformation or severing of coordination polyhedra in
+ultra-thin films drive rich properties that are radically different from the
+material's bulk physics.",2201.07058v1
+2022-01-20,Evaluation of the Thermal Stability of TiW/Cu Heterojunctions Using a Combined SXPS and HAXPES Approach,"Power semiconductor device architectures require the inclusion of a diffusion
+barrier to suppress, or at best prevent the interdiffusion between the copper
+metallisation interconnects and the surrounding silicon substructure. The
+binary pseudo-alloy of titanium-tungsten (TiW), with $>$70~at.\% W, is a well
+established copper diffusion barrier but is prone to degradation via the
+out-diffusion of titanium when exposed to high temperatures
+($\geq$400$^\circ$C). Here, the thermal stability of physical vapour deposited
+(PVD) TiW/Cu bilayer thin films in
+Si/SiO\textsubscript{2}(50~nm)/TiW(300~nm)/Cu(25~nm) stacks were characterised
+in response to annealing at 400$^\circ$C for 0.5~h and 5~h, using a combination
+of soft and hard X-ray photoelectron spectroscopy (SXPS and HAXPES) and
+transmission electron microscopy (TEM). Results show that annealing promoted
+the segregation of titanium out of the TiW and interdiffusion into the copper
+metallisation. Titanium was shown be driven toward the free copper surface,
+accumulating there and forming a titanium oxide overlayer upon exposure to air.
+Annealing for longer timescales promoted a greater out-diffusion of titanium
+and a thicker oxide layer to grow on the copper surface. However, interface
+measurements suggest that the diffusion is not significant enough to compromise
+the barrier integrity and the TiW/Cu interface remains stable even after 5~h of
+annealing.",2201.08074v1
+2022-01-24,Stability of Oxygenated Groups on Pristine and Defective Diamond Surfaces,"The surface functionalization of diamond has been extensively studied through
+a variety of techniques, such as oxidation. Several oxygen groups have been
+correspondingly detected on the oxidized diamond, such as COC (ester), CO
+(ketonic), and COH (hydroxyl). However, the composition and relative
+concentration of these groups on diamond surfaces can be affected by the type
+of oxygenation treatment and the diamond surface quality. To investigate the
+stability of the oxygenated groups at specific diamond surfaces, we evaluated
+through fully atomistic reactive molecular mechanics (FARMM) simulations, using
+the ReaxFF force field, the formation energies of CO, COC, and COH groups on
+pristine and defective diamond surfaces (110), (111), and (311). According to
+our findings, the COH group has the lowest formation energy on a perfect (110)
+surface, while the COC is favored on a defective surface. As for the (111)
+surface, the COC group is the most stable for both pristine and defective
+surfaces. Similarly, COC group is also the most stable one on the
+defective/perfect (311) surface. In this way, our results suggest that if in a
+diamond film the (110) surface is the major exposed facet, the most adsorbed
+oxygen group could be either COH or COC, in which the COC would depend on the
+level of surface defects.",2201.09690v1
+2022-01-28,Oxygen Deficient α-MoO3 with Promoted Adsorption and State-Quenching of H2O for Gas Sensor: A DFT Study,"Semiconducting oxides with reducible cations are ideal platforms for various
+functional applications in nanoelectronics and catalysts. Here we report an
+ultrathin monolayer alpha-MoO3 where tunable electronic properties and
+different gas adsorbing behaviors upon introducing the oxygen vacancies (VO).
+The unique property of alpha-MoO3 is that it contains three different types of
+oxygen atoms occupying three Wyckoff sites that are absent in other
+low-dimensional oxides and provides rich electronic hybridized states. The
+presence of VO triggers intermediate state in the gap at ~0.59 eV below the
+conduction band minimum and reduces the work function dramatically, together
+with new excitations at near infrared. The realigned Fermi level associated
+with the dangling state of VO reduces the neighboring Mo atoms and affects the
+gas adsorption thereafter. The binding energy of H2O molecules above VO is 2.5
+times up to -0.75 eV compared with that of perfect lattice site and trends of
+transfer of electrons also reverse. The latter is related with the shallow
+localized state in the band gap due to H2O adsorbed above perfect MoO3 which
+becomes quenched upon adsorbing at the VO site. Those rich in-gap defective
+states in oxygen deficient MoO3, broadening the light absorption and promoting
+the uptake of water, are conductive to the application of alpha-MoO3 for
+optoelectronics, photothermal therapy, and sensor of moisture.",2201.11900v1
+2022-02-06,Unexpectedly Spontaneous Water Dissociation on Graphene Oxide Supported by Copper Substrate,"Water dissociation is of fundamental importance in scientific fields and has
+drawn considerable interest in diverse technological applications. However, the
+high activation barrier of breaking the O-H bond within the water molecule has
+been identified as the bottleneck, even for the water adsorbed on the graphene
+oxide (GO). Herein, using the density functional theory calculations, we
+demonstrate that the water molecule can be spontaneously dissociated on GO
+supported by the (111) surface of the copper substrate (Copper-GO). This
+process involves a proton transferring from water to the interfacial oxygen
+group, and a hydroxide covalently bonding to GO. Compared to that on GO, the
+water dissociation barrier on Copper-GO is significantly decreased to be less
+than or comparable to thermal fluctuations. This is ascribed to the
+orbital-hybridizing interaction between copper substrate and GO, which enhances
+the reaction activity of interfacial oxygen groups along the basal plane of GO
+for water dissociation. Our work provides a novel strategy to access water
+dissociation via the substrate-enhanced reaction activity of interfacial oxygen
+groups on GO and indicates that the substrate can serve as an essential key to
+tuning the catalytic performance of various two-dimensional material devices.",2202.02746v2
+2022-02-16,Solution-processed van der Waals heterojunction as the damage-free gate contact for high performance GaN HEMTs,"The junctions formed between gate contact and III-nitride are crucial
+components of GaN-based electronics and optoelectronics. In this work,
+solution-processed inorganic Ti3C2Tx MXene films were spray coated on the
+AlGaN/GaN epitaxial wafer as the gate contact. The workfounction of MXene films
+was effectively enhanced by partial oxidization process, and accordingly, the
+gate leakage current and off-state drain current were significantly suppressed.
+The van der Waals heterojunction between MXene films and III-nitride without
+direct chemical bonding retained the pristine atomically flat native oxides of
+III-nitride, record high Ion/Ioff current ratio of 1013, and near ideal
+subthreshold swing of 61 mV/dec was achieved in the Schottky-Type gate GaN
+HEMTs. In addition, the MXene gate GaN HEMTs display superior electron mobility
+and transcoductance, high uniformity with 20 measured transistors. The
+unprecedented performance can be correlated to the damage-free interface
+between MXene and III-nitride, negligible atomic diffusion of MXene into the
+semiconductor layer, and excellent adhesion between MXene and III-nitride. This
+work provides an alternative method to create contact not only in GaN HEMTs but
+also in other electronic and optoelectronic devices which uniquely features
+cost-effective, non-vacuum, high deposition rate, and damage-free properties.",2202.08243v2
+2022-03-04,"Character of the ""normal state"" of the nickelate superconductors","The occurrence of superconductivity in proximity to various strongly
+correlated phases of matter has drawn extensive focus on their normal state
+properties, to develop an understanding of the state from which
+superconductivity emerges. The recent finding of superconductivity in layered
+nickelates raises similar interests. However, transport measurements of doped
+infinite-layer nickelate thin films have been hampered by materials limitations
+of these metastable compounds - in particular, a relatively high density of
+extended defects. Here, by moving to a substrate
+(LaAlO$_{3}$)$_{0.3}$(Sr$_{2}$TaAlO$_{6}$)$_{0.7}$ which better stabilizes the
+growth and reduction conditions, we can synthesize the doping series of
+Nd$_{1-x}$Sr$_{x}$NiO$_{2}$ essentially free from extended defects. This
+enables the first examination of the 'intrinsic' temperature and doping
+dependent evolution of the transport properties. The normal state resistivity
+exhibits a low-temperature upturn in the underdoped regime, linear behavior
+near optimal doping, and quadratic temperature dependence for overdoping. This
+is strikingly similar to the copper oxides, despite key distinctions - namely
+the absence of an insulating parent compound, multiband electronic structure,
+and a Mott-Hubbard orbital alignment rather than the charge-transfer insulator
+of the copper oxides. These results suggest an underlying universality in the
+emergent electronic properties of both superconducting families.",2203.02580v1
+2022-03-08,"Heteroepitaxial control of Fermi liquid, Hund metal, and Mott insulator phases in the single-atomic-layer limit","Interfaces between dissimilar correlated oxides can offer devices with
+versatile functionalities. In that respect, manipulating and measuring novel
+physical properties of oxide heterointerfaces are highly desired. Yet, despite
+extensive studies, obtaining direct information on their momentum-resolved
+electronic structure remains a great challenge. This is because most correlated
+interfacial phenomena appear within a few atomic layers from the interface,
+thus limiting the application of available experimental probes. Here, we
+utilize atomic-scale epitaxy and photoemission spectroscopy to demonstrate the
+interface control of correlated electronic phases in atomic-scale
+ruthenate--titanate heterostructures. While bulk SrRuO$_3$ is a ferromagnetic
+metal, the heterointerfaces exclusively realize three distinct correlated
+phases in the single-atomic-layer limit. Our theory reveals that atomic-scale
+structural proximity effects lead to the emergence of Fermi liquid, Hund metal,
+and Mott insulator phases in the quantum-confined SrRuO$_3$. These results
+highlight the extensive interfacial tunability of electronic phases, hitherto
+hidden in the atomically thin correlated heterostructure.",2203.04244v1
+2022-03-11,Tunable superconductivity at the oxide-insulator/KTaO$_3$ interface and its origin,"Superconductivity forms out of the condensation of Cooper pairs of electrons.
+The mechanism by which Cooper pairs are created in non-conventional
+superconductors is often elusive because experimental signatures that connect a
+specific pairing mechanism to the properties of superconducting state are rare.
+The recently discovered superconducting oxide-insulator/KTaO$_3$ interface may
+offer clues about its origins. Here we observe distinct dependences of the
+superconducting transition temperature Tc on carrier density n$_{2D}$ for
+electron gases formed at KTaO$_3$ (111), (001) and (110) interfaces. For the
+KTaO$_3$ (111) interface, a remarkable linear dependence of Tc on n$_{2D}$ is
+observed over a range of nearly one order of magnitude. Further, our study of
+the dependence of superconductivity on gate electric fields reveals the role of
+the interface in mediating superconductivity, which also allows for a
+reversible electric switching of superconductivity at T = 2 K. We found that
+the extreme sensitivity of superconductivity to crystallographic orientation
+can be explained by Cooper pairing via inter-orbital interactions induced by
+the inversion-breaking transverse optical (TO1) phonons and quantum
+confinement. This mechanism is also consistent with the dependence of Tc on
+n$_{2D}$ at the KTaO$_3$ (111) interface. Our study may shed light on the
+pairing mechanism in other superconducting quantum-paraelectrics.",2203.05867v1
+2022-03-18,X-ray Nano-imaging of Defects in Thin Film Catalysts via Cluster Analysis,"Functional properties of transition-metal oxides strongly depend on
+crystallographic defects. In transition-metal-oxide electrocatalysts such as
+SrIrO3 (SIO), crystallographic lattice deviations can affect ionic diffusion
+and adsorbate binding energies. Scanning x-ray nanodiffraction enables imaging
+of local structural distortions across an extended spatial region of thin
+samples. Line defects remain challenging to detect and localize using
+nanodiffraction, due to their weak diffuse scattering. Here we apply an
+unsupervised machine learning clustering algorithm to isolate the low-intensity
+diffuse scattering in as-grown and alkaline-treated thin epitaxially strained
+SIO films. We pinpoint the defect locations, find additional strain variation
+in the morphology of electrochemically cycled SIO, and interpret the defect
+type by analyzing the diffraction profile through clustering. Our findings
+demonstrate the use of a machine learning clustering algorithm for identifying
+and characterizing hard-to-find crystallographic defects in thin films of
+electrocatalysts and highlight the potential to study electrochemical reactions
+at defect sites in operando experiments.",2203.09980v2
+2022-04-05,Exploring Mechanisms of Hydration and Carbonation of MgO and Mg(OH)2 in Reactive Magnesium Oxide-based Cements,"Reactive magnesium oxide (MgO)-based cement (RMC) can play a key role in
+carbon capture processes. However, knowledge on the driving forces that control
+the degree of carbonation and hydration and rate of reactions in this system
+remains limited. In this work, density functional theory-based simulations are
+used to investigate the physical nature of the reactions taking place during
+the fabrication of RMCs under ambient conditions. Parametric indicators such as
+adsorption energies, charge transfer, electron localization function,
+adsorption/dissociation energy barriers and the mechanisms of interaction of
+H2O and CO2 molecules with MgO and brucite (Mg(OH)2) clusters are considered.
+The following hydration and carbonation interactions relevant to RMCs are
+evaluated i) carbonation of MgO, ii) hydration of MgO, carbonation of hydrated
+MgO, iii) carbonation of Mg(OH)2, iv) hydration of Mg(OH)2 and v) hydration of
+carbonated Mg(OH)2. A comparison of the energy barriers and reaction pathways
+of these mechanisms shows that the carbonation of MgO is hindered by presence
+of H2O molecules, while the carbonation of Mg(OH)2 is hindered by the formation
+of initial carbonate and hydrate layers as well as presence of excessed H2O
+molecules. To compare these finding to bulk mineral surfaces, the interactions
+of the CO2 and H2O molecules with the MgO(001) and Mg(OH)2 (001) surfaces are
+studied. Therefore, this work presents deep insights into the physical nature
+of the reactions and the mechanisms involved in hydrated magnesium carbonates
+production that can be beneficial for its development.",2204.01993v1
+2022-04-05,Unraveling the stable cathode electrolyte interface in all solid-state thin-film battery operating at 5V,"Spinel-type LiNi0.5Mn1.5O4 (LNMO) is one of the most promising 5 V-class
+cathode materials for Li-ion batteries that can achieve high energy density and
+low production costs. However, in liquid electrolyte cells, the high voltage
+causes continuous cell degradation through the oxidative decomposition of
+carbonate-based liquid electrolytes. In contrast, some solid-state electrolytes
+have a wide electrochemical stability range and can withstand the required
+oxidative potential. In this work, a thin-film battery consisting of a LNMO
+cathode with a solid lithium phosphorus oxynitride (LiPON) electrolyte is
+tested and their interface before and after cycling is characterized. With Li
+metal as the anode, this system can deliver stable performance for 600 cycles
+with an average Coulombic efficiency > 99%. Neutron depth profiling indicates a
+slight overlithiated layer at the interface prior to cycling; a result that is
+consistent with the excess charge capacity measured during the first cycle.
+Cryogenic electron microscopy further reveals intimate contact between LNMO and
+LiPON without noticeable structure and chemical composition evolution after
+extended cycling, demonstrating the superior stability of LiPON against a high
+voltage cathode. Consequently, we propose design guidelines for interface
+engineering that could accelerate the commercialization of a high voltage cell
+with solid or liquid electrolytes.",2204.02510v1
+2022-05-02,Atomic-scale Oxygen-mediated Etching of 2D MoS$_2$ and MoTe$_2$,"Some of the materials are more affected by oxidation than others. To
+elucidate the oxidation-induced degradation mechanisms in transition metal
+chalcogenides, the chemical effects in single layer MoS$_2$ and MoTe$_2$ were
+studied in situ in an electron microscope under controlled low-pressure oxygen
+environments at room temperature.Oxidation is the main cause of degradation of
+many two-dimensional materials, including transition metal dichalcogenides,
+under ambient conditions. MoTe$_2$ is found to be reactive to oxygen, leading
+to significant degradation above a pressure of 1$\times 10^{-7}$ torr.
+Curiously, the common hydrocarbon contamination found on practically all
+surfaces accelerates the damage rate significantly, by up to a factor of forty.
+In contrast to MoTe$_2$, MoS$_2$ is found to be inert under oxygen environment,
+with all observed structural changes being caused by electron irradiation only,
+leading to well-defined pores with high proportion of molybdenum
+nanowire-terminated edges. Using density functional theory calculations, a
+further atomic-scale mechanism leading to the observed oxygen-related
+degradation in MoTe$_2$ is proposed and the role of the carbon in the etching
+is explored. Together, the results provide an important insight into the
+oxygen-related deterioration of two-dimensional materials under ambient
+conditions relevant in many fields.",2205.00855v1
+2022-05-10,Fine and hyperfine excitation of nitric oxide by collision with para-H2,"Nitric oxide is an open-shell molecule abundantly detected in the
+interstellar medium. A precise modeling of its radiative and collisional
+processes opens the path to a precise estimate of its abundance. We present
+here the first rate coefficients for fine and hyperfine (de-)excitation of NO
+by collisions with the most ubiquitous collision partner in the interstellar
+medium, $para$-H$_2$ hydrogen molecules, using a recently developed accurate
+interaction potential. We report quantum scattering calculations for
+transitions involving the first 74 fine levels and the corresponding 442
+hyperfine levels belonging to both $F_1$ and $F_2$ spin-orbit manifolds. To do
+so, we have calculated cross sections by means of the quantum mechanical
+close-coupling approach up to 1000 cm$^{-1}$ of total energy and rate
+coefficients from 5 to 100 K. Propensity rules are discussed and the new
+NO-H$_2$ rates are compared to those available in the literature, based on
+scaled NO-He rates. Large differences are observed between the two sets of rate
+coefficients, and this comparison shows that the new collision rates must be
+used in interpreting NO emission lines. We also examined the effect of these
+new rates on the NO excitation in cold clouds by performing radiative transfer
+calculations of the excitation and brightness temperatures for the two NO lines
+at 150.176 and 250.4368 GHz. This shows that the local thermodynamic
+equilibrium is not fulfilled for this species for typical conditions. We expect
+the use of the rates presented in this study to improve the constraints on the
+abundance of NO.",2205.04863v1
+2022-05-11,Reversible Tuning of Superconductivity in Ion-Gated NbN Ultrathin Films by Self-Encapsulation with a High-$κ$ Dielectric Layer,"Ionic gating is a powerful technique for tuning the physical properties of a
+material via electric field-induced charge doping, but is prone to introduce
+extrinsic disorder and undesired electrochemical modifications in the gated
+material beyond pure electrostatics. Conversely, reversible, volatile and
+electrostatic modulation is pivotal in the reliable design and operation of
+novel device concepts enabled by the ultrahigh induced charge densities
+attainable via ionic gating. Here we demonstrate a simple and effective method
+to achieve reversible and volatile gating of surface-sensitive ultrathin
+niobium nitride films via controlled oxidation of their surface. The resulting
+niobium oxide encapsulation layer exhibits a capacitance comparable to that of
+non-encapsulated ionic transistors, withstands gate voltages beyond the
+electrochemical stability window of the gate electrolyte, and enables a
+fully-reversible tunability of both the normal-state resistivity and the
+superconducting transition temperature of the encapsulated films. Our approach
+should be transferable to other materials and device geometries where more
+standard encapsulation techniques are not readily applicable.",2205.05491v3
+2022-05-13,Tuning cryogenic Jahn-Teller transition temperatures in magnetoelectric rare earth vanadates,"Few materials undergo cooperative Jahn-Teller (JT) transitions at low
+temperatures, but zircon-type oxides are one class that includes DyVO$_4$,
+which transforms from a tetragonal to an orthorhombic structure at around 13.6
+K, with a narrow transition temperature range within 0.5 K. Since many
+rare-earth ions can be accommodated in the structure, there should be ample
+routes to vary the transition temperature and structural effects of the
+transition. We have synthesized pure DyVO$_4$ and solid solutions
+Dy$_{1-x}$Tm$_x$VO$_4$ ($x$ = 0.05, 0.1, 0.15, 0.2, and 0.5) and
+Dy$_{1-y}$Pr$_y$VO$_4$ ($y$ = 0.03, 0.05, 0.1, 0.2, and 0.5), all by solution
+precipitation. X-ray diffraction shows a systematic peak shift and a linear
+change of lattice parameters with increasing substitution. We demonstrate
+through heat capacity measurements that both Tm$^{3+}$ and Pr$^{3+}$
+substitutions cause a depression of the cooperative JT transition temperature.
+When the substitution level increases, the JT transition is eventually
+suppressed. We examine a mean-field approximation model that can explain the
+both the JT transition temperature shift and its eventual disappearance. The
+cooperative JT effect in these zircon-type oxides is known to exhibit a large
+magnetoelectric response, which should follow from the mean-field behavior. The
+structural transformation can be easily detected via diffraction and can be
+used as a temperature calibration in low temperature experiments.",2205.06856v1
+2022-05-14,Enhanced spectral broadening via self-phase modulation with femtosecond optical pulses in silicon nanowires integrated with 2D graphene oxide films,"We experimentally demonstrate enhanced spectral broadening of femtosecond
+optical pulses af-ter propagation through silicon-on-insulator (SOI) nanowire
+waveguides integrated with two-dimensional (2D) graphene oxide (GO) films.
+Owing to the strong mode overlap between the SOI nanowires and the GO films
+with a high Kerr nonlinearity, the self-phase modulation (SPM) process in the
+hybrid waveguides is significantly enhanced, resulting in greatly improved
+spectral broadening of the femtosecond optical pulses. A solution-based,
+transfer-free coating method is used to integrate GO films onto the SOI
+nanowires with precise control of the film thickness. Detailed SPM measurements
+using femtosecond optical pulses are carried out, achieving a broadening factor
+of up to ~4.3 for a device with 0.4-mm-long, 2 layers of GO. By fit-ting the
+experimental results with theory, we obtain an improvement in the waveguide
+nonlin-ear parameter by a factor of ~3.5 and the effective nonlinear figure of
+merit (FOM) by a factor of ~3.8, relative to the uncoated waveguide. Finally,
+we discuss the influence of GO film length on the spectral broadening and
+compare the nonlinear optical performance of different integrated waveguides
+coated with GO films. These results confirm the improved nonlinear optical
+per-formance for silicon devices integrated with 2D GO films.",2205.06942v1
+2022-05-26,Ultrahigh ion diffusion in oxide crystal by engineering the interfacial transporter channels,"The mass storage and removal in solid conductors always played vital role on
+the technological applications such as modern batteries, permeation membranes
+and neuronal computations, which were seriously lying on the ion diffusion and
+kinetics in bulk lattice. However, the ions transport was kinetically limited
+by the low diffusional process, which made it a challenge to fabricate
+applicable conductors with high electronic and ionic conductivities at room
+temperature. It was known that at essentially all interfaces, the existed space
+charge layers could modify the charge transport, storage and transfer
+properties. Thus, in the current study, we proposed an acid solution/WO3/ITO
+structure and achieved an ultrafast hydrogen transport in WO3 layer by
+interfacial job-sharing diffusion. In this sandwich structure, the transport
+pathways of the protons and electrons were spatially separated in acid solution
+and ITO layer respectively, resulting the pronounced increasing of effective
+hydrogen diffusion coefficient (Deff) up to 106 times. The experiment and
+theory simulations also revealed that this accelerated hydrogen transport based
+on the interfacial job-sharing diffusion was universal and could be extended to
+other ions and oxide materials as well, which would potentially stimulate
+systematic studies on ultrafast mixed conductors or faster solid-state
+electrochemical switching devices in the future.",2205.13414v1
+2022-05-31,Enhanced self-phase modulation in silicon nitride waveguides integrated with 2D graphene oxide films,"We experimentally demonstrate enhanced self-phase modulation (SPM) in silicon
+nitride (Si3N4) waveguides integrated with 2D graphene oxide (GO) films. GO
+films are integrated onto Si3N4 waveguides using a solution-based,
+transfer-free coating method that enables precise control of the film
+thickness. Detailed SPM measurements are carried out using both picosecond and
+femtosecond optical pulses. Owing to the high Kerr nonlinearity of GO, the
+hybrid waveguides show significantly improved spectral broadening compared to
+the uncoated waveguide, achieving a broadening factor of up to ~3.4 for a
+device with 2 layers of GO. By fitting the experimental results with theory, we
+obtain an improvement in the waveguide nonlinear parameter by a factor of up to
+18.4 and a Kerr coefficient (n2) of GO that is about 5 orders of magnitude
+higher than Si3N4. Finally, we provide a theoretical analysis for the influence
+of GO film length, coating position, and its saturable absorption on the SPM
+performance. These results verify the effectiveness of on-chip integrating 2D
+GO films to enhance the nonlinear optical performance of Si3N4 devices.",2205.15817v1
+2022-05-31,Functionalization of graphene sponge electrodes with two-dimensional materials for tailored electrocatalytic activity towards specific contaminants of emerging concern,"Low-cost graphene sponge electrodes were functionalized with two-dimensional
+(2D) materials, i.e., borophene and hexagonal boron nitride (hBN), using a
+one-step, hydrothermal self-assembly method. Borophene and hBN-modified
+graphene sponge anode and N-doped graphene sponge cathode were employed for
+electrochemical degradation of model persistent contaminants of emerging
+concern in one-pass, flow through mode, and using low-conductivity supporting
+electrolyte. Functionalization of the reduced graphene oxide (RGO) coating with
+2D materials led to specific modifications in the electrode electrocatalytic
+performance and interactions with the target contaminants. For instance,
+addition of hBN promoted the adsorption of more hydrophobic organic
+contaminants via van der Waals and {\pi}-{\pi} interactions. Functionalization
+of the graphene sponge anode with borophene enhanced the generation of oxidant
+species such as H2O2 and O3 and yielded an order of magnitude higher
+concentration of hydroxyl radicals (HO) compared with the non-functionalized
+graphene sponge anode, thus enhancing the removal of target contaminants.
+Experiments conducted with the selective radical scavengers indicated the key
+role of surface-bound hydroxyl radicals (HOads) and singlet oxygen (1O2) in
+electrochemical degradation. The study demonstrates that functionalization of
+graphene sponge electrodes with 2D materials can enhance their electrocatalytic
+activity and modulate the interaction with specific organic contaminants, thus
+opening new possibilities for designing electrodes tailored to remove specific
+groups of pollutants.",2206.04111v1
+2022-06-09,Dynamics of H atoms surface recombination in low-temperature plasma,"The dynamics of H atom recombination on materials of interest for a EUV
+lithographer was studied under a longterm low-pressure H2 plasma exposure. The
+similarity of the experimental plasma with the typical EUV-induced plasma over
+the multi-layer mirrors (MLMs) surface of the EUV lithographic machine is
+demonstrated by means of 2D PIC MC simulation. The measurement of the temporal
+dynamics of the H atom surface loss probability is chosen for testing the
+surface modification during the treatment. Time-resolved actinometry of H atoms
+with Kr as the actinometer gas was used to detect the dynamics of the H-atom
+loss probability on the surface of Al, Ru, RVS and SiO2. It is demonstrated
+that significant changes of the materials surface occur only at the very
+beginning of the treatment and ist due to the surface heating and cleaning
+effects. After that no changes of the H recombination rate are found,
+indicating that the surface stays absolutely stable. A special test of the
+sensitivity of the used method to the state of surface was carried out.
+Dynamics of the H recombination rate changes with the small O2 addition clearly
+demonstrated modification of the Al surface due to oxidation with the next
+removal of the oxygen by the H2 plasma treatment. The rate of oxide removal is
+shown to be determined by plasma parameters such as the ion energy and flux to
+the surface.",2206.04391v1
+2022-06-23,Modulation doping of the FeSe monolayer on SrTiO$_3$,"The discovery of higher-temperature superconductivity in FeSe monolayers on
+SrTiO$_3$ (STO) substrates has sparked a surge of interest in the interface
+superconductivity. One point of the agreement reached to date is that
+modulation doping by impurities in the substrate is critical for the enhanced
+superconductivity. Remarkably, the universal doping of about 0.1 electrons per
+Fe, \textit{i.e.}, so-called ``magic'' doping, has been observed on a range of
+Ti oxide substrates, which concludes that there likely is some important
+interaction limiting the FeSe doping. Our study discovers that the polarization
+change at the interface Se because of the close proximity to the substrate from
+that in the free-standing FeSe film significantly amplifies the total potential
+difference at the interface above and beyond the work function difference for
+charge transfer. Additionally, the titanate substrate with a large number of
+free electrons basically serves as an ``infinite'' charge reservoir, which
+leads to the saturated FeSe doping with the complete removal of interface
+potential gradient. Our work has developed the theory for modulation doping in
+the Van der Waals materials/oxides heterostructure, providing a solution to the
+puzzle of ``magic'' doping in FeSe monolayers on titanates. The information
+also presents experimental pathways to accommodate a variable carrier density
+of FeSe monolayers via modulation doping.",2206.11945v1
+2022-06-26,Atomically imprinted graphene plasmonic cavities,"Plasmon polaritons in van der Waals (vdW) materials hold promise for
+next-generation photonics. The ability to deterministically imprint spatial
+patterns of high carrier density in cavities and circuitry with nanoscale
+features underlies future progress in nonlinear nanophotonics and strong
+light-matter interactions. Here, we demonstrate a general strategy to
+atomically imprint low-loss graphene plasmonic structures using
+oxidation-activated charge transfer (OCT). We cover graphene with a monolayer
+of WSe$_2$, which is subsequently oxidized into high work-function WOx to
+activate charge transfer. Nano-infrared imaging reveals low-loss plasmon
+polaritons at the WOx/graphene interface. We insert WSe$_2$ spacers to
+precisely control the OCT-induced carrier density and achieve a near-intrinsic
+quality factor of plasmons. Finally, we imprint canonical plasmonic cavities
+exhibiting laterally abrupt doping profiles with single-digit nanoscale
+precision via programmable OCT. Specifically, we demonstrate technologically
+appealing but elusive plasmonic whispering-gallery resonators based on
+free-standing graphene encapsulated in WOx. Our results open avenues for novel
+quantum photonic architectures incorporating two-dimensional materials.",2206.12754v1
+2022-06-27,From Si Nanowires to Ge Nanocrystals for VIS-NIR-SWIR Sensors and Non-volatile Memories: A Review,"Nanocrystalline Si and Ge are of high interest for integrated Si photonics
+related to light emission, optical sensors, photodetectors, solar energy
+harvesting and conversion devices, and also for floating gate non-volatile
+memories (NVMs). In this review, we have focused on nanocrystalline porous Si
+(nc-PS) with extension to Si nanodots, and Ge nanocrystals (NCs)/quantum dots
+(QDs)/nanoparticles (NPs) embedded in oxides (SiO$_2$, TiO$_2$, HfO$_2$,
+Al$_2$O$_3$). The great asset of nc-PS is its intense photoluminescence in VIS
+at room temperature (RT), while Ge NCs/NPs embedded in oxides show high
+photosensitivity in VIS-NIR-SWIR in the spectral photocurrent up to 1325 nm at
+RT. Ge NCs/NPs/QDs floating gate NVMs present high memory performance, the
+retention characteristics corresponding to the state of the art for NCs
+floating gate NVMs. We prove the relevance of controlling the preparation
+parameters for obtaining films with targeted photoluminescence,
+photosensitivity and charge storage properties for applications, e.g.
+VIS-NIR-SWIR optical sensors and photodetectors, and electronic and
+photoelectric NVMs. We evidence the correlation of preparation conditions,
+morphology, composition and crystalline structure with optical, electrical,
+photoelectrical and charge storage properties and also evidence the
+contribution of quantum confinement effect, localized states and trapping
+centers.",2206.13260v1
+2022-07-01,"Trends in Bandgap of Epitaxial $\textit{A}$$_2$$\textit{B}$$_2$O$_7$ ($\textit{A}$ = Sn, Pb; $\textit{B}$ = Nb, Ta) Films Fabricated by Pulsed Laser Deposition","Pyrochlore oxides $A_2B_2$O$_7$ have been a fruitful playground for condensed
+matter physics because of the unique geometry in the crystal structure.
+Especially focusing on the $A$-site tetrahedral sub-lattice, in particular,
+pyrochlore oxides $A_2B_2$O$_7$ ($A$ = Sn, Pb and $B$ = Nb, Ta), recent
+theoretical studies predict the emergence of the ""quasi-flat band"" structure as
+a result of the strong hybridization between filled $A$-n$s$ and O-2$p$
+orbitals. In this work, we have established the growth conditions of
+Sn$_2$Nb$_2$O$_7$, Sn$_2$Ta$_2$O$_7$, Pb$_2$Nb$_2$O$_7$, and Pb$_2$Ta$_2$O$_7$
+films by pulsed laser deposition on Y-stabilized ZrO$_2$ (111) substrates to
+elucidate their optical properties. Absorption-edge energies, both for direct
+and indirect bandgaps, increase in the order of Sn$_2$Nb$_2$O$_7$,
+Sn$_2$Ta$_2$O$_7$, Pb$_2$Nb$_2$O$_7$, and Pb$_2$Ta$_2$O$_7$. This tendency can
+be well explained by considering the energy level of the constituent elements.
+A comparison of the difference between direct and indirect bandgaps reveals
+that Pb$_2B_2$O$_7$ tends to have a less dispersive valence band than
+Sn$_2B_2$O$_7$. Our findings are consistent with the theoretical predictions
+and are suggestive of the common existence of the hybridized states in this
+class of compounds.",2207.00434v1
+2022-06-10,"Fabrication of Periodic, Flexible and Porous Silicon Microwire Arrays with Controlled Diameter and Spacing: Effects on Optical properties","A new method of introducing nanopores with spongy morphology during
+fabrication of size and pitch controlled flexible silicon microwires (SiMWs) in
+wafer scale is presented using nanosphere lithography technique in addition to
+metal catalyzed electroless etching technique by varying concentration of
+oxidant and introducing surfactant or co-solvents to the etching solution. For
+achieving self-assembled monolayer closed-pack pattern of SiO2 microparticles
+in wafer-scale simple spin coating process was used. The effect of variation of
+the etchant, oxidant and surfactant on the morphology and optical properties of
+SiMWs were studied. By simply controlling the diameter of SiO2 microparticles
+and concentration of H2O2 the size of the MWs as well as the introduction of
+pores could be controlled in wafer-scale. Average reflectance suppressed to
+below 8% in the broad spectral range of 400-800 nm for these porous, spongy and
+flexible SiMW arrays in wafer scale. The mechanism behind this formation of
+spongy, porous and flexible nature of the SiMWs is also demonstrated for a
+better understanding of the etching process.",2207.06487v1
+2022-07-15,Band-Engineered LaFeO$_{3}$-LaNiO$_{3}$ Thin Film Interfaces for Electrocatalysis of Water,"Transition metal oxides have generated significant interest for their
+potential as catalysts for the oxygen evolution reaction (OER) in alkaline
+environments. Iron and nickel-based perovskite oxides have proven particularly
+promising, with catalytic over-potentials rivaling precious metal catalysts
+when the alignment of the valence band relative to the OER reaction potential
+is tuned through substitutional doping or alloying. Here we report that
+engineering of band alignment in LaFeO$_{3}$/LaNiO$_{3}$ (LFO/LNO)
+heterostructures via interfacial doping yields greatly enhanced catalytic
+performance. Using density functional theory modeling, we predict a 0.2 eV
+valence band offset (VBO) between metallic LNO and semiconducting LFO that
+significantly lowers the barrier for hole transport through LFO compared to the
+intrinsic material and make LFO a p-type semiconductor. Experimental band
+alignment measurements using in situ X-ray photoelectron spectroscopy of
+epitaxial LFO/LNO heterostructures agree quite well with these predictions,
+producing a measured VBO of 0.3(1) eV. OER catalytic measurements on the same
+samples in alkaline solution show an increase in catalytic current density by a
+factor of ~275 compared to LFO grown on n-type Nb-doped SrTiO$_{3}$. These
+results demonstrate the power of tuning band alignments through interfacial
+band engineering for improved catalytic",2207.07264v1
+2022-07-15,Tunable intervalence charge transfer in ruthenium Prussian blue analogue enables stable and efficient biocompatible artificial synapses,"Emerging concepts for neuromorphic computing, bioelectronics, and
+brain-computer interfacing inspire new research avenues aimed at understanding
+the relationship between oxidation state and conductivity in unexplored
+materials. Here, we present ruthenium Prussian blue analogue (RuPBA), a mixed
+valence coordination compound with an open framework structure and ability to
+conduct both ionic and electronic charge, for flexible artificial synapses that
+reversibly switch conductance by more than four orders of magnitude based on
+electrochemically tunable oxidation state. Retention of programmed states is
+improved by nearly two orders of magnitude compared to the extensively studied
+organic polymers, thus reducing the frequency, complexity and energy costs
+associated with error correction schemes. We demonstrate dopamine detection
+using RuPBA synapses and biocompatibility with neuronal cells, evoking
+prospective application for brain-computer interfacing. By application of
+electron transfer theory to in-situ spectroscopic probing of intervalence
+charge transfer, we elucidate a switching mechanism whereby the degree of mixed
+valency between N-coordinated Ru sites controls the carrier concentration and
+mobility, as supported by DFT.",2207.07756v1
+2022-07-29,The electronic and thermal response of low electron density Drude materials to ultrafast optical illumination,"Many low electron density Drude (LEDD) materials such as transparent
+conductive oxide or nitrides have recently attracted interest as alternative
+plasmonic materials and future nonlinear optical materials. However, the
+rapidly growing number of experimental studies has so far not been supported by
+a systematic theory of the electronic, thermal and optical response of these
+materials. Here, we use the techniques previously derived in the context of
+noble metals to go beyond a simple electromagnetic modelling of low electron
+density Drude materials and provide an electron dynamics model for their
+electronic and thermal response. We find that the low electron density makes
+momentum conservation in electron-phonon interactions more important, more
+complex and more sensitive to the temperatures compared with noble metals;
+moreover, we find that electron-electron interactions are becoming more
+effective due to the weaker screening. Most importantly, we show that the low
+electron density makes the electron heat capacity much smaller than in noble
+metals, such that the electrons in LEDD materials tend to heat up much more and
+cool down faster compared to noble metals. While here we focus on indium tin
+oxide (ITO), our analytic results can be easily applied to any LEDD materials.",2207.14528v1
+2022-08-01,Preferred corrosion pathways for oxygen in Al2Ca-twin boundaries and dislocations,"With an ongoing discussion on the oxygen diffusion along crystal defects
+remaining, it is difficult to study this phenomenon in Al containing
+intermetallic materials due to its rapid and passivating oxide formation. We
+report here the observation of enhanced oxygen diffusion along crystal defects,
+i.e. dislocations and twin boundaries, in the C15 Al 2 Ca Laves phase and how
+the presence of oxygen induces structural changes at these defects. Three main
+phases were identified and characterized structurally by aberration-corrected,
+atomic resolution scanning transmission electron microscopy, analytically by
+energy dispersive X-ray spectroscopy and electron energy loss spectroscopy.
+Unlike the C15 bulk phase, the twin boundary and dislocation transformed into a
+few nanometer wide amorphous phase, which depletes in Al and Ca but is highly
+enriched in oxygen. The dislocation even shows coexistence of the amorphous
+phase with a simple Al-rich A1 fcc phase. This A1 phase only depletes in Ca,
+not in Al (Al remains at bulk concentration), and is also enriched in oxygen.
+The Al-rich A1 phase is coherent with the C15 matrix. Electron energy loss
+spectroscopy revealed the amorphous phase to be Al 2 O 3 . We thereby show as
+one of the first studies that oxygen diffusion along crystal defects,
+especially also at the twin boundary can induce the formation of an amorphous
+oxide along themselves. The identification of oxygen-induced transformation at
+strained defects has to be considered when the material is exposed to air
+during plastic deformation at elevated temperatures.",2208.01116v2
+2022-08-16,Towards the simulation of transition-metal oxides of the cathode battery materials using VQE methods,"Variational quantum eigensolver (VQE) is a hybrid quantum-classical technique
+that leverages noisy intermediate scale quantum (NISQ) hardware to obtain the
+minimum eigenvalue of a model Hamiltonian. VQE has so far been used to simulate
+condensed matter systems as well as quantum chemistry of small molecules. In
+this work, we employ VQE methods to obtain the ground-state energy of
+LiCoO$_2$, a candidate transition metal oxide used for battery cathodes. We
+simulate Li$_2$Co$_2$O$_4$ and Co$_2$O$_4$ gas-phase models, which represent
+the lithiated and delithiated states during the discharge and the charge of the
+Li-ion battery, respectively. Computations are performed using a statevector
+simulator with a single reference state for three different trial
+wavefunctions: unitary coupled-cluster singles and doubles (UCCSD), unitary
+coupled-cluster generalized singles and doubles (UCCGSD) and k-unitary pair
+coupled-cluster generalized singles and doubles (k-UpCCGSD). The resources in
+terms of circuit depth, two-qubit entangling gates and wavefunction parameters
+are analyzed. We find that the k-UpCCGSD with k=5 produces results similar to
+UCCSD but at a lower cost. Finally, the performance of VQE methods is
+benchmarked against the classical wavefunction-based methods, such as
+coupled-cluster singles and doubles (CCSD) and complete active space
+configuration interaction (CASCI). Our results show that VQE methods
+quantitatively agree with the results obtained from CCSD. However, the
+comparison against the CASCI results clearly suggests that advanced trial
+wavefunctions are likely necessary to capture the multi-reference
+characteristics as well as the correlations emerging from high-level electronic
+excitations.",2208.07977v1
+2022-08-18,"Nanoscale mapping of sub-gap electroluminescence from step-bunched, oxidized 4H-SiC surfaces","Scanning tunneling luminescence microscopy (STLM) along with scanning
+tunneling spectroscopy (STS) is applied to a step-bunched, oxidized 4H-SiC
+surface prepared on the silicon face of a commercial, n-type SiC wafer using a
+silicon melt process. The step-bunched surface consists of atomically smooth
+terraces parallel to the [0001] crystal planes, and rougher risers consisting
+of nanoscale steps formed by the termination of these planes. The rather
+striking topography of this surface is well resolved with large tip biases of
+the order of -8 V and set currents of magnitude less than 1 nA. Hysteresis in
+the STS spectra is preferentially observed on the risers suggesting that they
+contain a higher density of surface charge traps than the terraces where
+hysteresis is more frequently absent. Similarly, at 50 K intense sub-gap light
+emission centered around 2.4 eV is observed mainly on the risers albeit only
+with larger tunneling currents of magnitude equal to or greater than 10 nA.
+These results demonstrate that STLM holds great promise for the observation of
+impurities and defects responsible for sub-gap light emission with spatial
+resolutions approaching the length scale of the defects themselves.",2208.08775v1
+2022-08-14,Energy-Exergy Analysis and Optimal Design of a Hydrogen Turbofan Engine,"In this study, the effect of inlet air cooling and fuel type on the
+performance parameters of thrust-specific fuel consumption (TSFC), thermal and
+exergetic efficiencies, entropy generation rate, and Nitrogen oxide emission
+intensity index (SNOx) of the GENX 1B70 engine is analyzed in two states of
+take-off and on design. The results show that with a 20-degree delicious
+reduction in inlet air temperature on design conditions and JP10 fuel usage,
+the thermal efficiency and entropy generation rate, thrust and fuel mass flow
+rate, and TSFC of the engine increase by 1.85 percent, 16.51 percent, 11.76
+percent, 10.53 percent, and 2.15 percent and SNOx and exergetic efficiency
+decrease by 2.11 percent and 26.60 percent, respectively. Also, optimization of
+the GENX 1B70 engine cycle as hydrogen fuel usage with three separate objective
+functions: thrust maximization, thermal efficiency maximization, and propulsive
+efficiency maximization on design point condition was performed based on the
+Genetic algorithm. Based on the economic approach and exero-environmental, the
+best cycles from the optimal states were selected using the TOPSIS algorithm.
+In on design conditions, entropy generation rate, nitrogen oxide production
+rate, and TSFC for the chosen cycle based on the economic approach +18.89
+percent, +10.01 percent, and -0.21percent, respectively, and based on the
+exero-environmental approach -54.03percent, -42.02percent, and +21.44percent
+change compared to the base engine, respectively.",2208.08890v1
+2022-08-19,Anomalous electrochemical capacitance in Mott insulator titanium sesquioxide,"Electrochemical capacitors with pure electric double layer capacitance are so
+far largely been limited to carbon materials only. Conventional metal oxides
+with Faradaic pseudocapacitance substantially suffer from material instability
+at high temperatures and thus there is a demand for novel metal oxides
+exhibiting thermally improved high electric double layer capacitance with
+material stability. In this study, titanium sesquioxide, Ti$_2$O$_3$, a Mott
+insulator in its metallic state at 300$^o$ C showed an anomalous increase of
+$\approx$ 560% in the solid-state electrochemical capacitance as compared to
+its pristine response at room temperature (RT). In aqueous electrolyte, the
+maximum capacitance was obtained up to 1053 $\mu$F/cm$^2$, which is 307% higher
+than with solid-state electrolyte. Moreover, the semiconducting state of
+Ti$_2$O$_3$ demonstrated $\approx$ 3500% enhancement in its electrochemical
+capacitance upon infrared illumination at RT. The observed electrochemical
+responses in Ti$_2$O$_3$ are attributed to the transition of semiconducting to
+the metallic state by redistribution of the localized electrons. Our
+experimental results find a good agreement with the first-principles
+density-functional theory calculations that revealed an increase in the charge
+density with the rise in temperature, which is mainly attributed to the surface
+Ti atoms. The study open has wide avenues to engineer the electrochemical
+double layer capacitance of theory calculations that revealed an increase in
+the charge density with the rise in temperature, which is mainly attributed to
+the surface Ti atoms. The study opens wide avenues to engineer the
+electrochemical double layer capacitance of Ti$_2$O$_3$ with high chemical
+stability.",2208.09436v1
+2022-08-23,"Hydrogen in Disordered Titania: Connecting Local Chemistry, Structure, and Stoichiometry through Accelerated Exploration","Hydrogen incorporation in native surface oxides of metal alloys often
+controls the onset of metal hydriding, with implications for materials
+corrosion and hydrogen storage. A key representative example is titania, which
+forms as a passivating layer on a variety of titanium alloys for structural and
+functional applications. These oxides tend to be structurally diverse,
+featuring polymorphic phases, grain boundaries, and amorphous regions that
+generate a disparate set of unique local environments for hydrogen. Here, we
+introduce a workflow that can efficiently and accurately navigate this
+complexity. First, a machine learning force field, trained on ab initio
+molecular dynamics simulations, was used to generate amorphous configurations.
+Density functional theory calculations were then performed on these structures
+to identify local oxygen environments, which were compared against experimental
+observations. Second, to classify subtle differences across the disordered
+configuration space, we employ a graph-based sampling procedure. Finally, local
+hydrogen binding energies are computed using exhaustive density functional
+theory calculations on representative configurations. We leverage this
+methodology to show that hydrogen binding energetics are described by local
+oxygen coordination, which in turn is affected by stoichiometry. Together these
+results imply that hydrogen incorporation and transport in TiO$_x$ can be
+tailored through compositional engineering, with implications for improving
+performance and durability of titanium-derived alloys in hydrogen environments.",2208.10956v1
+2022-08-23,Direction-Dependent Lateral Domain Walls in Ferroelectric Hafnium Zirconium Oxide and their Gradient Energy Coefficients: A First Principles Study,"To understand and harness the physical mechanisms of ferroelectric Hafnium
+Zirconium Oxide (HZO)-based devices, there is a need for clear understanding of
+domain interactions, their dynamics, negative capacitance effects, and other
+multi-domain characteristics. These crucial attributes depend on the coupling
+between neighboring domains quantified by the gradient energy coefficient (g).
+Furthermore, HZO has unique orientation-dependent lateral multidomain
+configurations. To develop an in-depth understanding of multi-domain effects,
+there is a need for thorough analysis of g. In this work, the energetics of
+multidomain configurations and domain growth mechanism corresponding to lateral
+domain walls of HZO are analyzed and gradient energy coefficients are
+quantified using first-principles Density Functional Theory calculations. These
+results indicate that one lateral direction exhibits the following
+characteristics: i) DW is ultra-sharp and domain growth occurs
+unit-cell-by-unit-cell, ii) the value of g is negative and in the order of
+$10^{-12} Vm^{3}C^{-1}$, and iii) g reduces (increases) with compressive
+(tensile) strain. In contrast, in the other lateral direction, the following
+attributes are observed: i) DW is gradual and domain growth occurs in quanta of
+half-unit-cell, ii) g is positive and in the order of $10^{-10} Vm^{3}C^{-1}$,
+and iii) g increases (reduces) with compressive (tensile) strain.",2208.11029v4
+2022-08-28,"Homologous self-assembled superlattices: What causes their periodic polarity switching? Review, model, and experimental test","Quantum semiconductor structures are commonly achieved by bandgap engineering
+that relies on the ability to switch from one semiconductor to another during
+their growth. Growth of a superlattice is typically demanding technologically.
+In contrast, accumulated evidence points to a tendency among a certain class of
+multiple-cation binary oxides to self-assemble spontaneously as superlattice
+structures. This class has been dubbed the homologous superlattices. For a
+famous example, when a mixture of indium and zinc is oxidized, the phases of
+In-O and ZnO separate in an orderly periodic manner, along the ZnO polar axis,
+with polarity inversion taking place between consecutive ZnO sections. As we
+review here, the same structure has been observed when the indium was replaced
+with other metals, and perhaps even in ZnO alone. This peculiar self-assembled
+structure has been attracting research over the past decade. The purpose of
+this study is to gain understanding of the physics underlying the formation of
+this unique structure. Here, we first provide an extensive review of the
+accumulated literature on these spontaneously-formed structures and then
+propose an explanation for the long-standing mystery of this intriguing
+self-assembly in the form of an electrostatic growth phenomenon and test the
+proposed model on experimental data.",2208.13155v1
+2022-09-09,Rapid oxygen exchange between hematite and water vapor,"Oxygen exchange at oxide/liquid and oxide/gas interfaces is important in
+technology and environmental studies, as it is closely linked to both catalytic
+activity and material degradation. The atomic-scale details are mostly unknown,
+however, and are often ascribed to poorly defined defects in the crystal
+lattice. Here we show that even thermodynamically stable, well-ordered surfaces
+can be surprisingly reactive. Specifically, we show that all the 3-fold
+coordinated lattice oxygen atoms on a defect-free single-crystalline r-cut
+(1-102) surface of hematite ({\alpha}-Fe2O3) are exchanged with oxygen from
+surrounding water vapor within minutes at temperatures below 70 {\deg}C, while
+the atomic-scale surface structure is unperturbed by the process. A similar
+behavior is observed after liquid water exposure, but the experimental data
+clearly show most of the exchange happens during desorption of the final
+monolayer, not during immersion. Density functional theory computations show
+that the exchange can happen during on-surface diffusion, where the cost of the
+lattice oxygen extraction is compensated by the stability of an HO-HOH-OH
+complex. Such insights into lattice oxygen stability are highly relevant for
+many research fields ranging from catalysis and hydrogen production to
+geochemistry and paleoclimatology.",2209.04205v1
+2022-09-14,Structural peculiarities of $\varepsilon$-Fe$_2$O$_3$ / GaN epitaxial layers unveiled by high-resolution transmission electron microscopy and neutron reflectometry,"The present paper is dedicated to the structural study of crystallographic
+peculiarities appearing in epitaxial films of metastable epsilon iron oxide
+($\varepsilon$-Fe$_2$O$_3$) grown by pulsed laser deposition onto a
+semiconductor GaN (0001) substrate. The columnar structure of the nanoscale
+$\varepsilon$-Fe$_2$O$_3$ films has been for the first time investigated using
+high resolution electron microscopy (HRTEM) direct space technique complemented
+by reciprocal space methods of high-energy electron diffraction and
+color-enhanced HRTEM image Fourier filtering. The study of
+$\varepsilon$-Fe$_2$O$_3$ / GaN interface formation has been further expanded
+by carrying out a depth resolved analysis of density and chemical composition
+by neutron reflectometry and energy-dispersive X-ray spectroscopy. The obtained
+results shed light onto the properties and the origin of the enigmatic
+few-nanometer thick low density transition layer residing at the
+$\varepsilon$-Fe$_2$O$_3$ / GaN interface. A detailed knowledge of the
+properties of this layer is believed to be highly important for the development
+of $\varepsilon$-Fe$_2$O$_3$ / GaN heterostructures that can potentially become
+part of the iron-oxide based ferroic-on-semiconductor devices with room
+temperature magneto-electric coupling.",2209.06460v1
+2022-09-15,Spin-charge coupling and decoupling in perovskite-type iron oxides (Sr$_{1-x}$Ba$_x$)$_{2/3}$La$_{1/3}$FeO$_3$,"The perovskite-type iron oxide Sr$_{2/3}$La$_{1/3}$FeO$_3$ is known to show
+characteristic spin-charge ordering (SCO), where sixfold collinear spin
+ordering and threefold charge ordering are coupled with each other. Here, we
+report the discovery of a spin-charge decoupling and an antiferromagnetic (AFM)
+state competing with the SCO phase in perovskites
+(Sr$_{1-x}$Ba$_x$)$_{2/3}$La$_{1/3}$FeO$_3$. By comprehensive measurements
+including neutron diffraction, M$\""{o}$ssbauer spectroscopy, and x-ray
+absorption spectroscopy, we found that the isovalent Ba$^{2+}$ substitution
+systematically reduces the critical temperature of the SCO phase and
+additionally yields the spin-charge decoupling in $x$ > 0.75. Whereas the
+ground state remains in the SCO phase in the whole $x$ region, an unexpected
+G-type AFM phase with incoherent charge ordering or charge fluctuation appears
+as the high-temperature phase in the range of $x$ > 0.75. Reflecting the
+competing nature between them, the G-type AFM phase partially exists as a
+metastable state in the SCO phase at low temperatures. We discuss the origin of
+the spin-charge decoupling and the emergence of the G-type AFM phase with
+charge fluctuation in terms of the bandwidth reduction by the Ba substitution.",2209.07310v1
+2022-09-18,A facile top-down synthesis of phase pure CuBi2O4 photocathode materials by low-energy sequential ball milling,"Kusachiite (copper bismuth oxide) is one of the most promising photocathode
+materials for high solar-to-hydrogen production efficiency. Here we attempt to
+synthesize phase pure copper bismuth oxide (CuBi2O4) nanopowders using a facile
+solid-state reaction technique, subsequently sintered at 750 0C for 4 h in air.
+These CuBi2O4 (CBO) powders have been further sequentially ball-milled (SBM) up
+to 25 h to elucidate the milling duration effect on the optical bandgap of the
+ball-milled CuBi2O4 (SBM-CBO). The X-ray diffractometry (XRD), Raman, X-ray
+Photoelectron spectroscopy (XPS), and UV-VIS-NIR Diffuse reflection studies
+suggest that phase pure tetragonal CBO could be grown from raw CuO and Bi2O3
+powders. The variations in morphology and chemical composition of CBO with
+increasing milling hours were examined using field emission scanning electron
+microscopy (FE-SEM) and Energy Dispersive X-ray (EDX) microanalysis,
+respectively. The optical bandgap of SBM-CBO powders was measured in the range
+of approx. 1.70 - 1.85 eV. Photoelectrochemical studies of SBM-CBO slurry atop
+the screen-printed electrode with aqueous Na2SO4 electrolyte suggest its
+suitability as photocathode materials for sunlight-driven hydrogen production.",2209.08530v2
+2022-09-23,Excitonic effects in X-ray absorption spectra of fluoride salts and their surfaces,"Operando X-ray absorption spectroscopy (XAS) can probe the
+electrode-electrolyte interface with single-digit nanometer depth resolution
+and offers a wealth of insight into the evolution and Coulombic efficiency or
+degradation of prototype cells, provided that the spectra can be reliably
+interpreted in terms of local oxidation state, atomic coordination, and
+electronic structure aboutthe excited atoms. To this end, we explore fluorine
+K-edge XAS of mono- (Li, Na, K) and di-valent (Mg, Ca, Zn) fluoride salts from
+a theoretical standpoint and discover a surprising level of detailed electronic
+structure information about these materials, despite the relatively predictable
+oxidation state and ionicity of the fluoride anion and the metal cation.
+Utilizing a recently developed many-body approach based on the delta-SCF
+method, we calculate the XAS using density functional theory and experimental
+spectral profiles are well reproduced, despite some experimental discrepancies
+in energy alignment within the literature, which we can correct for in our
+simulations. We outline a general methodology to explain shifts in the main XAS
+peak energies in terms of a simple exciton model and explain line-shape
+differences resulting from mixing of core-excited states with metal d character
+(for K and Ca specifically). Given ultimate applications to evolving
+interfaces, some understanding of the role of surfaces and their terminations
+in defining new spectral features is provided to indicate the sensitivity of
+such measurements to changes in interfacial chemistry.",2209.11845v1
+2022-09-24,Energy-Environment evaluation and Forecast of a Novel Regenerative turboshaft engine combine cycle with DNN application,"In this integrated study, a turboshaft engine was evaluated by adding inlet
+air cooling and regenerative cooling based on energy-environment analysis.
+First, impacts of flight-Mach number, flight altitude, the compression ratio of
+compressor-1 in the main cycle, the turbine inlet temperature of turbine-1 in
+the main cycle, temperature fraction of turbine-2, the compression ratio of the
+accessory cycle, and inlet air temperature variation in inlet air cooling
+system on some functional performance parameters of Regenerative turboshaft
+engine cycle equipped with inlet air cooling system such as power-specific fuel
+consumption, Power output, thermal efficiency, and mass flow rate of Nitride
+oxides (NOx) including NO and NO2 has been investigated via using hydrogen as
+fuel working. Consequently, based on the analysis, a model was developed to
+predict the energy-environment performance of the Regenerative turboshaft
+engine cycle equipped with a cooling air cooling system based on a deep neural
+network (DNN) with 2 hidden layers with 625 neurons for each hidden layer. The
+model proposed to predict the amount of thermal efficiency and the mass flow
+rate of nitride oxide (NOx) containing NO and NO2. The results demonstrated the
+accuracy of the integrated DNN model with the proper amount of the MSE, MAE,
+and RMSD cost function for both predicted outputs to validate both testing and
+training data. Also, R and R^2 are noticeably calculated very close to 1 for
+both thermal Efficiency and NOx emission mass flow rate for both validations of
+thermal efficiency and NOx emission mass flow rate prediction values with its
+training and its testing data.",2209.12020v1
+2022-09-26,Quality Control (QC) of FBK Preproduction 3D Si Sensors for ATLAS HL-LHC Upgrades,"The challenging demands of the ATLAS High Luminosity (HL-LHC) Upgrade aim for
+a complete swap of new generation sensors that should cope with the ultimate
+radiation hardness. FBK has been one of the prime foundries to develop and
+fabricate such radiation-hard 3D silicon (Si) sensors. These sensors are chosen
+to be deployed into the innermost layer of the ATLAS Inner Tracker (ITk).
+Recently, a pre-production batch of 3D Si sensors of 50x50 um2 pixel geometry,
+compatible with the full-size ITKPix (RD53B) readout chip, was fabricated. Two
+wafers holding temporary metal were diced at IZM, Germany, and a systematic QC
+test campaign was carried out at the University of Trento electronics
+laboratory. The paper briefly describes the 3D Si sensor design for ATLAS ITk
+and the required QC characterization setups. It comprises electrical tests
+(i.e., I-V, C-V, and I-T) of non-irradiated RD53B sensors. In addition, the
+study of several parametric analyses, i.e., oxide charge density, oxide
+thickness, inter-pixel resistance, inter-pixel capacitance, etc., are reported
+with the aid of Process Control Monitor (PCM) structures.",2209.12991v2
+2022-09-27,Evaluation and comparison of NiO/CuO nanocomposite and NiO nanofibers as non-enzymatic electrochemical cholesterol biosensor,"Fabrication of a highly sensitive non-enzymatic electrochemical sensor for
+the detection of cholesterol is a challenging issue due to its low redox
+activity. In the present study, the electrochemical response of a novel
+combination of metal oxides has been explored. NiO/CuO nanocomposite was
+fabricated by electrospinning method and its morphology and structural
+characteristics were studied using scanning electron microscopy, EDX and X-ray
+diffraction techniques. Electrochemical studies revealed that the NiO/CuO/GC
+electrode poses a linear detection range between 0.8 to 6.5 mM, low detection
+limit of 5.9 microM and a sensitivity of 10.27 microA.mM-1 .cm-2 in the neutral
+buffer solution. The fabricated electrode has a response time of 3 seconds and
+a good ability to discriminate interfering species. Moreover, the nanocomposite
+electrode exhibited high stability as well as the other favorable factors,
+makes it an effective sensor for the detection of cholesterol. In addition,
+cyclic voltammetry experiments showed that the current response of NiO/GCE is
+approximately 30 % of the NiO/CuO/GCE response, suggesting that the
+nanocomposite has a greater electrocatalytic activity towards cholesterol
+oxidation than NiO nanofibers. NiO/GCE results showed the sensitivity of 2.5
+microA.mM-1 .cm-2 , response time of 2 seconds and a limited stability over
+three-week time span.",2209.13144v1
+2022-10-01,Stochastic Paleoclimatology: Modeling the EPICA Ice Core Climate Records,"We analyze and model the stochastic behavior of paleoclimate time series and
+assess the implications for the coupling of climate variables during the
+Pleistocene glacial cycles. We examine 800 kyr of carbon dioxide, methane,
+nitrous oxide, and temperature proxy data from the EPICA Dome-C ice core, which
+are characterized by 100~kyr glacial cycles overlain by fluctuations across a
+wide range of time scales. We quantify this behavior through multifractal
+time-weighted detrended fluctuation analysis, which distinguishes near
+red-noise and white-noise behavior below and above the 100~kyr glacial cycle
+respectively in all records. This allows us to model each time series as a
+one-dimensional periodic non-autonomous stochastic dynamical system, and assess
+the stability of physical processes and the fidelity of model-simulated time
+series. We extend this approach to a four-variable model with linear coupling
+terms, which we interpret in terms of the interrelationships between the time
+series. Methane and nitrous oxide are found to have significant destabilizing
+influences, while carbon dioxide and temperature have smaller stabilizing
+influences. We draw conclusions about causal relationships in glacial
+transitions and the climate processes that may have facilitated these
+couplings, and highlight opportunities to further develop stochastic modeling
+approaches.",2210.00308v2
+2022-10-19,Predicting Oxide Glass Properties with Low Complexity Neural Network and Physical and Chemical Descriptors,"Due to their disordered structure, glasses present a unique challenge in
+predicting the composition-property relationships. Recently, several attempts
+have been made to predict the glass properties using machine learning
+techniques. However, these techniques have the limitations, namely, (i)
+predictions are limited to the components that are present in the original
+dataset, and (ii) predictions towards the extreme values of the properties,
+important regions for new materials discovery, are not very reliable due to the
+sparse datapoints in this region. To address these challenges, here we present
+a low complexity neural network (LCNN) that provides improved performance in
+predicting the properties of oxide glasses. In addition, we combine the LCNN
+with physical and chemical descriptors that allow the development of universal
+models that can provide predictions for components beyond the training set. By
+training on a large dataset (~50000) of glass components, we show the LCNN
+outperforms state-of-the-art algorithms such as XGBoost. In addition, we
+interpret the LCNN models using Shapely additive explanations to gain insights
+into the role played by the descriptors in governing the property. Finally, we
+demonstrate the universality of the LCNN models by predicting the properties
+for glasses with new components that were not present in the original training
+set. Altogether, the present approach provides a promising direction towards
+accelerated discovery of novel glass compositions.",2210.10507v1
+2022-10-25,Ultrafast ion sieving in two dimensional graphene oxide membranes,"Ultrahigh water permeance, together with a high rejection rate through
+nanofiltration and separation membranes1,2, is crucial but still challenging
+for multivalent ion sieving in water treatment processes of desalination,
+separation, and purification3,4. To date, no theory or equation has ever been
+quantitatively clarified the mechanism of water permeance in two-dimensional
+(2D) membranes, despite intensive and prolonged searches. Here, we established
+a new general equation of permeation through 2D membranes, and experimentally
+achieved unprecedented advances in water permeance one to two orders of
+magnitude higher than state-of-the-art membranes while simultaneously
+maintaining high ion rejection rates for multivalent metal ions, by staking
+nano-sized reduced graphene oxide (nano-rGO) flakes into nanofiltration
+membranes. The equation is simply based on a fundamental steady-state flow
+assumption and provides an essential description of water permeance through 2D
+membranes, demonstrating that the ultrahigh water permeance is attributed to
+the high effective channel area and shortened channel length elicited from the
+nano-sized-flake stacking effects in nano-rGO membranes, consistent with our
+theoretical simulations and previous experiments. These results pave the way
+for fabrication of advanced 2D nanofiltration membranes to realize a
+breakthrough in water permeance with exceptional ion sieving performance.",2210.13707v1
+2022-10-26,Direct observation of two-dimensional small polarons at correlated oxide interface,"Two-dimensional (2D) perovskite oxide interfaces are ideal systems where
+diverse emergent properties can be uncovered.The formation and modification of
+polaronic properties due to short-range strong charge-lattice interactions of
+2D interfaces remains hugely intriguing.Here, we report the direct observation
+of small-polarons at the LaAlO3/SrTiO3 (LAO/STO) conducting interface using
+high-resolution spectroscopic ellipsometry.First-principles investigations
+further reveals that strong coupling between the interfacial electrons and the
+Ti-lattice result in the formation of localized 2D small polarons.These
+findings resolve the longstanding issue where the excess experimentally
+measured interfacial carrier density is significantly lower than theoretically
+predicted values.The charge-phonon induced lattice distortion further provides
+an analogue to the superconductive states in magic-angle twisted bilayer
+graphene attributed to the many-body correlations induced by broken periodic
+lattice symmetry.Our study sheds light on the multifaceted complexity of broken
+periodic lattice induced quasi-particle effects and its relationship with
+superconductivity.",2210.14440v2
+2022-11-02,One-Step Formation of Plasmonic Cu Nanodomains in p-Type Cu$_2$O Matrix Films for Enhanced Photoconversion of n-ZnO/p-Cu$_2$O Heterojunctions,"Plasmonic Cu nanoparticles were in-situ grown into a Cu$_2$O semiconductor
+matrix by using reactive magnetron sputtering and adjusting the amount of
+oxygen available during the synthesis in order to prevent the oxidation of part
+of copper atoms landed on the film surface. Varying only the oxygen flowrate
+(OFR) and using a single Cu target it was possible to observe the evolution in
+the simultaneous formation of metallic Cu and Cu$_2$O phases for oxygen-poor
+conditions. Suchformation is accompanied by the development of the surface
+plasmon band (SPB) corresponding to Cu, as evidenced by UV-Vis
+spectrophotometry and spectroscopic ellipsometry. The bandgap values of the
+elaborated composites containing embedded Cu plasmonic nanodomains were lower
+than the bandgap of single-phased Cu$_2$O films, likely due to the higher
+defect density associated to the nanocrystalline nature of films, promoted by
+the presence of metallic Cu. The resistivity of the thin films increased with
+more oxidative deposition conditions and was associated to an increase in
+Cu$_2$O/Cu ratio and smaller and more isolated Cu particles, as evidenced by
+high resolution transmission electron microscopy and X-ray diffraction.
+Photoconversion devices based on the studied nanocomposites were characterized
+by I-V and spectral photocurrent measurements, showing an increase in the
+photocurrent density under light illumination as consequence of the plasmonic
+particles excitation leading to hot carrier's injection in the nearby ZnO and
+Cu$_2$O semiconductors.",2211.01010v1
+2022-11-09,Ultra-clean isotope engineered double-walled carbon nanotubes as tailored hosts to trace the growth of carbyne,"Increasing attention is currently given to carbyne, the sp1 hybridized
+one-dimensional carbon allotrope, because of its predicted outstanding
+mechanical, optical, and electrical properties. Although recently substantial
+progress has been reported on confined carbyne synthesized inside double-walled
+carbon nanotubes (DWCNTs), its formation mechanism and precursors for growth
+remain elusive. Here, we show a rational design of isotope engineered
+ultra-clean DWCNTs as tailored hosts to trace the growth of carbyne, which
+allows to identify the precursor and unravel the formation mechanism of carbyne
+during high-vacuum annealing at high-temperatures. Using this approach,
+ultra-clean DWCNTs with 80.4% 13C-enriched inner walls and outer tubes of
+naturally abundant served to unambiguously prove that only the carbonaceous
+materials inside the DWCNTs can act as precursors. The exchange of C atoms
+between inner and outer tubes happens without any growth of carbyne. After
+applying a secondary oxidation step, it is possible to produce the carbonaceous
+precursors from the partially oxidized DWCNTs. In this manner, not only carbyne
+with a record of ~28.8% 13C enrichment is grown, but concomitant healing,
+reorganization and regrowth of the DWCNTs occurs. This work enables to identify
+the precursor and trace the growth mechanism of confined carbyne with
+engineered properties. This is a crucial step, towards accessing the full
+application potential of confined carbyne hybrids by tailoring not only the
+isotopic fillers, but also the inner and outer tubes of the DWCNT hosts.",2211.04852v1
+2022-11-11,The Impact of Inter-grain Phases on the Ionic Conductivity of LAGP Solid Electrolyte Prepared by Spark Plasma Sintering,"Li1.5Al0.5Ge1.5(PO4)3 (LAGP) is a promising oxide solid electrolyte for
+all-solid-state batteries due to its excellent air stability, wide
+electrochemical stability window and cost-effective precursor materials.
+However, further improvement in their ionic conductivity performance is
+hindered by the presence of inter-grain phases leading to a major obstacle to
+the advanced design of oxide based solid-state electrolytes. This study
+establishes and quantifies the influence of inter-grain phases, their 3D
+morphology, and formed compositions on the overall ion conductivity properties
+of LAGP pellets fabricated under different Spark plasma sintering conditions.
+Based on complementary techniques, such as PEIS, XRD, 3D FIB-SEM tomography and
+solid-state MAS NMR coupled with DFT modelling, a deep insight into the
+inter-grain phase microstructures is obtained revealing that the inter-grain
+region is comprised of Li4P2O7 and a disordered Li9Al3(P2O7)3(PO4)2 phase. We
+demonstrate that optimal ionic conductivity for the LAGP system is achieved for
+the 680 {\deg}C SPS preparation when the disordered Li9Al3(P2O7)3(PO4)2 phase
+dominates the inter-grain region composition with reduced contributions from
+the highly ordered Li4P2O7 phases.",2211.06129v1
+2022-11-12,"Theoretical investigation of the physical properties of cubic perovskite oxides $SrXO_3 \;(X =Sc,\; Ge,\; Si)$","Various physical properties (electronic, optical and thermoelectric) of cubic
+perovskite oxides $SrXO_3\; (X=Sc,\; Ge,\; Si)$ are investigated by using the
+density functional theory (DFT) within Wien2k code. This code is based on
+different approximations such as generalized gradient approximation GGA,
+PBEsol, LDA, WC and the modified Becke-Johnson exchange potentials (mBJ, nmBJ
+and unmBJ). Structural properties and the optimization have been calculated
+using PBEsol functional which showed a significant results that are in good
+agreement with the experimental ones. The results for physical properties such
+as electronic, thermoelectric and optical are analyzed in detail by using the
+nmBJ approximation. The obtained results present an opening gap for $SrSiO_3$,
+$SrGeO_3$ and a metallic behavior for $SrScO_3$. An average of transmittance
+which is about $94\%$ to $97\%$ was observed in the range of visible light. The
+increase of electrical conductivity with temperature confirms the effect of
+thermal agitation on the concentration of charges carriers using BolzTrap
+Package. Lastly a phonon dispersion was made and show that for $X=\; Ge$ and
+$Si$, the structure is relatively stable while $SrScO_3$ is dynamically
+unstable. These results prove the ability that these materials can be exploited
+in many applications and manufacturing of optoelectronics for Sensors.",2211.06622v1
+2022-11-15,Data-driven design of new catalytic materials in methane oxidation based on a site isolation concept,"The conversion of natural gas (methane) to ethane and ethylene (OCM:
+oxidative coupling of methane) facilitates its transportation and provides a
+way to synthesize higher value chemicals. The search for high-performance
+catalysts to achieve this conversion is the main scope of most corresponding
+studies in the field of OCM. Here, we present a general data-driven strategy
+for the search of novel catalytic materials, focusing particularly on materials
+useful for the OCM reaction. Our strategy is based on consistent experimental
+measurements and includes ab initio thermodynamics calculations and active
+screening. Based on our experiments, which showed unique volcano-type
+dependence of the performance on the stability of formed carbonates attributed
+to the site isolation concept, we developed a method for efficient and
+inexpensive DFT calculations of the formation energies of carbonates with
+prediction accuracy 0.2 eV. This method was implemented into a high-throughput
+screening scheme, which includes both general requirements for catalyst
+candidates and an actively done artificial intelligence part. Experimental
+validation of some of the candidates obtained during the screening showed
+successful reproduction of the initial volcano dependence. Moreover, several
+new materials were found to outperform standard OCM catalysts, specifically at
+lower temperatures.",2211.08014v1
+2022-11-15,Exploring the nanoscale origin of performance enhancement in Li$_{1.1}$Ni$_{0.35}$Mn$_{0.55}$O$_2$ batteries due to chemical doping,"Despite significant potential as energy storage materials for electric
+vehicles due to their combination of high energy density per unit cost and
+reduced environmental and ethical concerns, Co-free lithium ion batteries based
+off layered Mn oxides presently lack the longevity and stability of their
+Co-containing counterparts. Here, we demonstrate a reduction in this
+performance gap via chemical doping, with Li$_{1.1}$Ni$_{0.35}$Mn$_{0.55}$O$_2$
+achieving an initial discharge capacity of 159 mAhg$^{-1}$ at C/3 rate and a
+corresponding capacity retention of 94.3% after 150 cycles. We subsequently
+explore the nanoscale origins of this improvement through a combination of
+advanced diffraction, spectroscopy, and electron microscopy techniques, finding
+that optimized doping profiles lead to an improved structural and chemical
+compatibility between the two constituent sub-phases that characterize the
+layered Mn oxide system, resulting in the formation of unobstructed lithium ion
+pathways between them. We also directly observe a structural stabilization
+effect of the host compound near the surface using aberration corrected
+scanning transmission electron microscopy and integrated differential phase
+contrast imaging.",2211.08060v1
+2022-11-23,Mesoscopic modeling and experimental validation of thermal and mechanical properties of polypropylene nanocomposites reinforced by graphene-based fillers,"The development of nanocomposites relies on structure-property relations,
+which necessitate multiscale modeling approaches. This study presents a
+modelling framework that exploits mesoscopic models to predict the thermal and
+mechanical properties of nanocomposites starting from their molecular
+structure. In detail, mesoscopic models of polypropylene (PP) and graphene
+based nanofillers (Graphene (Gr), Graphene Oxide (GO), and reduced Graphene
+Oxide (rGO)) are considered. The newly developed mesoscopic model for the PP/Gr
+nanocomposite provides mechanistic information on the thermal and mechanical
+properties at the filler-matrix interface, which can be then exploited to
+enhance the prediction accuracy of traditional continuum simulations by
+calibrating the thermal and mechanical properties of the filler-matrix
+interface. Once validated through a dedicated experimental campaign, this
+multiscale model demonstrates that with the modest addition of nanofillers (up
+to 2 wt.%), the Young's modulus and thermal conductivity show up to 35% and 25%
+enhancement, respectively, while the Poisson's ratio slightly decreases. Among
+the different combinations tested, PP/Gr nanocomposite shows the best
+mechanical properties, whereas PP/rGO demonstrates the best thermal
+conductivity. This validated mesoscopic model can contribute to the development
+of smart materials with enhanced mechanical and thermal properties based on
+polypropylene, especially for mechanical, energy storage, and sensing
+applications.",2211.13148v2
+2022-11-28,Amorphous ultra-wide bandgap ZnOx thin films deposited at cryogenic temperatures,"Crystalline wurtzite zinc oxide (w-ZnO) can be used as a wide band gap
+semiconductor for light emitting devices and for transparent or high
+temperature electronics. The use of amorphous zinc oxide (a-ZnO) can be an
+advantage in these applications. In this paper we report on X-ray amorphous
+a-ZnOx thin films (~500 nm) deposited at cryogenic temperatures by reactive
+magnetron sputtering. The substrates were cooled by a nitrogen flow through the
+copper substrate holder during the deposition. The films were characterized by
+X-ray diffraction (XRD), Raman, infrared, UV-Vis-NIR spectroscopies, and
+ellipsometry. The a-ZnOx films on glass and Ti substrates were obtained at the
+substrate holder temperature of approximately -100 oC. New vibration bands at
+201, 372, and 473 cm-1 as well as O-H stretch and bend absorption bands in the
+a-ZnOx films were detected by FTIR spectroscopy. Raman spectra showed
+characteristic ZnO2 peaks at 386 and 858 cm-1 attributed to the peroxide ion
+O22- stretching and libration modes, respectively. In addition, the films
+contain neutral and ionized O2 and O2- species. The a-ZnOx films are highly
+transparent in the visible light range (approx. 87%) and exhibit a refractive
+index of 1.68 at 2.25 eV (550 nm). An optical band gaps is 4.65 eV with an
+additional band edge absorption feature at 3.50 eV. It has been shown that the
+deposition on actively cooled substrates can be a suitable technique to obtain
+low temperature phases that cannot be deposited at room temperature.",2211.15219v1
+2022-11-29,Tripling energy storage density through order-disorder transition induced polar nanoregions in PbZrO3 thin films by ion implantation,"Dielectric capacitors are widely used in pulsed power electronic devices due
+to their ultrahigh power densities and extremely fast charge/discharge speed.
+To achieve enhanced energy storage density, both maximum polarization (Pmax)
+and breakdown strength (Eb) need to be improved simultaneously. However, these
+two key parameters are inversely correlated. In this study, order-disorder
+transition induced polar nanoregions (PNRs) have been achieved in PbZrO3 thin
+films by making use of the low-energy ion implantation, enabling us overcome
+the trade-off between high polarizability and breakdown strength, which leads
+to the tripling of the energy storage density from 20.5 J/cm3 to 62.3 J/cm3 as
+well as the great enhancement of breakdown strength. This approach could be
+extended to other dielectric oxides to improve the energy storage performance,
+providing a new pathway for tailoring the oxide functionalities.",2211.15896v1
+2022-11-29,Manufacturing high-Q superconducting α-tantalum resonators on silicon wafers,"The performance of state-of-the-art superconducting quantum devices is
+currently limited by microwave dielectric losses at different surfaces and
+interfaces. {\alpha}-tantalum is a superconductor that has proven effective in
+reducing dielectric loss and improving device performance due to its thin
+low-loss oxide. However, without the use of a seed layer, this tantalum phase
+has so far only been realised on sapphire substrates, which is incompatible
+with advanced processing in industry-scale fabrication facilities. Here, we
+demonstrate the fabrication of high-quality factor {\alpha}-tantalum resonators
+directly on silicon wafers over a variety of metal deposition conditions and
+perform a comprehensive material and electrical characterization study. By
+comparing experiments with simulated resonator loss, we demonstrate that
+two-level-system loss is dominated by surface oxide contributions and not the
+substrate-metal interface. Our study paves the way to large scale manufacturing
+of low-loss superconducting circuits and to materials-driven advancements in
+superconducting circuit performance.",2211.16437v2
+2022-12-09,Non-stationary thermophysical characterization of exfoliated graphite with carbon nanotubes composites,"The sheet samples of thermally exfoliated graphite (TEG) carbon nanotubes
+(CNT) composites (TEG CNT cs) were obtained by persulphate oxidation using
+chemical (CO) and electrochemical (anode) oxidation (ECAO). Electron microscopy
+reveals multi layered structures of few layer graphene nanosheets with folded
+and tubular like fragments.Electron microscopy reveals multilayered structures
+of few layer graphene nanosheets with folded and tubular like fragments. The
+effective thermal diffusivity values were estimated by nonstationary
+photo-pyroelectric thermophysical characterization using the heat pulse and
+thermo-wave modulation methods. Comparison with other carbon (C) based thermal
+management materials shows that TEG CNTcs exhibit thermal diffusivity,
+effusivity and conductivity comparable with those of actual C polymer and C C
+composites. For TEG CNT cs, evaluated values of phonon mean free path (MFP) and
+relaxation time (RT) are in the ranges estimated for defective graphene. The
+values of diffusivity and effusivity, MFP and RT are lower for denser TEG CNT
+cs obtained by ECAO and are higher for less dense TEG CNT cs obtained by CO.
+The obtained diffusivity and effusivity values designate TEG CNT cs as suitable
+thermal management materials.",2212.05036v1
+2022-12-13,Acceptor and compensating donor doping of single crystalline SnO (001) films grown by molecular beam epitaxy and its perspectives for optoelectronics and gas-sensing,"(La and Ga)-doped tin monoxide (stannous oxide, tin (II) oxide, SnO) thin
+films were grown by plasma-assisted and suboxide molecular beam epitaxy with
+dopant concentrations ranging from $\approx5\times10^{18}$cm$^{-3}$ to
+$2\times10^{21}$cm$^{-3}$. In this concentration range, the incorporation of Ga
+into SnO was limited by the formation of secondary phases observed at
+$1.2\times10^{21}$cm$^{-3}$ Ga, while the incorporation of La showed a lower
+solubility limit. Transport measurements on the doped samples reveal that Ga
+acts as an acceptor and La as a compensating donor. While Ga doping led to an
+increase of the hole concentration from
+$1\times10^{18}$cm$^{-3}-1\times10^{19}$cm$^{-3}$ for unintentionally (UID) SnO
+up to $5\times10^{19}$cm$^{-3}$, La-concentrations well in excess of the UID
+acceptor concentration resulted in semi-insulating films without detectable
+$n$-type conductivity. Ab-initio calculations qualitatively agree with our
+dopant assignment of Ga and La, and further predict In$_\text{Sn}$ to act as an
+acceptor as well as Al$_\text{Sn}$ and B$_\text{Sn}$ as donor. These results
+show the possibilities of controlling the hole concentration in $p$-type SnO,
+which can be useful for a range of optoelectronic and gas-sensing applications.",2212.06350v1
+2022-12-15,Lasing in a ZnO waveguide: clear evidence of polaritonic gain obtained by monitoring the continuous exciton screening,"The stimulated emission of exciton-polaritons was proposed as a means of
+lowering the lasing threshold because it does not require the dissociation of
+excitons to obtain an electron-hole plasma, as in a classical semiconductor
+laser based on population inversion. In this work we propose a method to prove
+unambiguously the polaritonic nature of lasing by combining experimental
+measurements with a model accounting for the permittivity change as a function
+of the carrier density. To do so we use angle resolved photoluminescence to
+observe the lasing at cryogenic temperature from a polariton mode in a zinc
+oxide waveguide structure, and to monitor the continuous shift of the
+polaritonic dispersion towards a photonic dispersion as the optical intensity
+of the pump is increased (up to 20 times the one at threshold). This shift is
+reproduced thanks to a model taking into account the reduction of the
+oscillator strength and the renormalization of the bandgap due to the screening
+of the electrostatic interaction between electrons and holes. Furthermore, the
+measurement of the carriers lifetime at optical intensities in the order of
+those at which the polariton lasing occurs enables us to estimate the carrier
+density, confirming it is lower than the corresponding Mott density for zinc
+oxide reported in the literature.",2212.07842v2
+2022-12-30,Transition metal ion ensembles in crystals as solid-state coherent spin-photon interfaces: The case of nickel in magnesium oxide,"We present general guidelines for finding solid-state systems that could
+serve as coherent electron spin-photon interfaces even at relatively high
+temperatures, where phonons are abundant but cooling is easier, and show that
+transition metal ions in various crystals could comply with these guidelines.
+As an illustrative example, we focus on divalent nickel ions in magnesium
+oxide. We perform electron spin resonance spectroscopy and
+polarization-sensitive magneto-optical fluorescence spectroscopy of a dense
+ensemble of these ions and find that (i) the ground-state electron spin stays
+coherent at liquid-helium temperatures for several microseconds, and (ii) there
+exists energetically well-isolated excited states which can couple to two
+ground state spin sub-levels via optical transitions of orthogonal
+polarizations. The latter implies that fast, coherent optical control over the
+electron spin is possible. We then propose schemes for optical initialization
+and control of the ground-state electron spin using polarized optical pulses,
+as well as two schemes for implementing a noise-free, broadband quantum-optical
+memory at near-telecom wavelengths in this material system.",2212.14827v2
+2023-01-09,High pressure bulk synthesis of InN by solid state reaction of binary oxide in a multi-anvil apparatus,"We present a new method to synthesize bulk indium nitride by means of a
+simple solid-state chemical reaction carried out under hydrostatic high
+pressure/high temperature conditions in a multi-anvil apparatus, not involving
+gases or solvents during the process. The reaction occurs between the binary
+oxide $In_2O_3$ and the highly reactive $Li_3N$ as nitrogen source, in powder
+form. The formation of the hexagonal phase of InN, occurring at 350 {\deg}C and
+P $\geq$ 3 GPa, was successfully confirmed by powder X-ray diffraction, with
+the presence of $Li_2O$ as unique byproduct. A simple washing process in weak
+acidic solution followed by centrifugation, allowed to obtain pure InN
+polycrystalline powders as precipitate. With an analogous procedure it was
+possible to obtain pure bulk GaN, from $Ga_2O_3$ and $Li_3N$ at T $\geq$
+600{\deg}C and P $\geq$ 2.5 GPa. These results point out, particularly for InN,
+a clean, and innovative way to produce significant quantities of one of the
+most promising nitrides in the field of electronics and energy technologies.",2301.03460v2
+2023-01-24,Design and Fabrication of PERC-Like CdTe Solar Cells Using Micropatterned Al2O3 Layer,"Recent studies have investigated novel strategies to further improve the
+limited Voc of CdTe solar cells via increased carrier lifetime and doping
+density of CdTe thin films. Among various metal oxides, aluminum oxide (Al2O3)
+is a promising passivation candidate, where the negatively charged Al2O3 layer
+repels the minority carrier in CdTe and Al2O3 provides a chemically passivating
+interface, increasing the carrier lifetime. Despite the continuing efforts, an
+optimized back-contact architecture to improve the Voc while maintaining high
+Jsc and FF is still under development. In this work, we report the design,
+fabrication, and characterization of PERC-like CdTe solar cells, where an Al2O3
+passivation layer is patterned using laser-beam lithography. Our process
+enables reproducible patterning on a rough surface CdTe while maintaining the
+size of the array in the design. Analysis of CdTe PERC devices (As-doped) shows
+a notably different Voc trend compared to FF and Jsc, independent of the
+patterned array structures used in this study. The subsurface electronic
+structure of CdTe and the interplay between carrier selectivity and collection
+of the patterned Al2O3 could be responsible for the observed PV
+characteristics.",2301.09787v1
+2023-01-24,The importance of tight $f$ basis functions for heavy p-block oxides and halides: a parallel with tight $d$ functions in the second row,"It is well-known that both wavefunction ab initio and DFT calculations on
+second-row compounds exhibit anomalously slow basis set convergence unless the
+basis sets are augmented with additional `tight' (high-exponent) $d$ functions,
+as in the cc-pV($n+d$)Z and aug-cc-pV($n+d$)Z basis sets. This has been
+rationalized as being necessary for a better description of the low-lying $3d$
+orbital, which as the oxidation state increases sinks low enough to act as a
+back-donation acceptor from chalcogen and halogen lone pairs. This prompts the
+question whether a similar phenomenon exists for the isovalent compounds of the
+heavy p-block. We show that for the fourth and fifth row, this is the case, but
+this time for tight $f$ functions enhancing the description of the low-lying
+$4f$ and $5f$ Rydberg orbitals, respectively. In the third-row heavy $p$ block,
+the $4f$ orbitals are too far up, while the $4d$ orbitals are adequately
+covered by the basis functions already present to describe the $3d$ subvalence
+orbitals.",2301.10098v2
+2023-01-30,Graphene Oxide Photoreduction Recovers Graphene Hot Electron Cooling Dynamics,"Reduced graphene oxide (rGO) is a bulk-processable quasi-amorphous 2D
+material with broad spectral coverage and fast electronic response. rGO sheets
+are suspended in a polymer matrix and sequentially photoreduced while measuring
+the evolving optical spectra and ultrafast electron relaxation dynamics.
+Photoreduced rGO yields optical absorption spectra that fit with the same Fano
+lineshape parameters as monolayer graphene. With increasing photoreduction
+time, rGO transient absorption kinetics accelerate monotonically, reaching an
+optimal point that matches the hot electron cooling in graphene. All stages of
+rGO ultrafast kinetics are simulated with a hot-electron cooling model mediated
+by disorder-assisted supercollisions. While the rGO room temperature 0.31
+ps$^{-1}$ electronic cooling rate matches monolayer graphene, subsequent
+photoreduction can rapidly increase the rate by ~10-12$\times$. Such
+accelerated supercollision rates imply a reduced mean-free scattering length
+caused by photoionized point-defects on the rGO sp$^2$ sub-lattice. For visible
+range excitations of rGO, photoreduction shows three increasing spectral peaks
+that match graphene quantum dot (GQD) transitions, while a broad peak from
+oxygenated defect edge states shrinks. These three confined GQD states donate
+their hot carriers to the graphene sub-lattice with a 0.17 ps rise-time that
+accelerates with photoreduction. Collectively, many desirable photophysical
+properties of 2D graphene are replicated through selectively reducing rGO
+scaffolded within a 3D bulk polymeric network.",2301.13176v1
+2023-02-03,Interface-tuning of ferroelectricity and quadruple-well state in CuInP$_2$S$_6$ via ferroelectric oxide,"Ferroelectric van der Waals CuInP$_2$S$_6$ possesses intriguing
+quadruple-well states and negative piezoelectricity. Its technological
+implementation has been impeded by the relatively low Curie temperature (bulk
+$T_C$ ~42 {\deg}C) and the lack of precise domain control. Here we show that
+CuInP$_2$S$_6$ can be immune to the finite size effect and exhibits enhanced
+ferroelectricity, piezoelectricity, and polar alignment in the ultrathin limit
+when interfaced with ferroelectric oxide PbZr$_{0.2}$Ti$_{0.8}$O$_3$ films.
+Piezoresponse force microscopy studies reveal that the polar domains in thin
+CuInP$_2$S$_6$ fully conform to those of underlying
+PbZr$_{0.2}$Ti$_{0.8}$O$_3$, where the piezoelectric coefficient changes sign
+and increases sharply with reducing thickness. High temperature $in$ $situ$
+domain imaging points to a significantly enhanced $T_C$ exceeding 200 {\deg}C
+for 13 nm CuInP$_2$S$_6$ on PbZr$_{0.2}$Ti$_{0.8}$O$_3$. Density functional
+theory modeling and Monte Carlo simulations show that the enhanced polar
+alignment and $T_C$ can be attributed to interface-mediated structure
+distortion in CuInP$_2$S$_6$. Our study provides an effective material strategy
+to engineer the polar properties of CuInP$_2$S$_6$ for flexible nanoelectronic,
+optoelectronic, and mechanical applications.",2302.01504v2
+2023-02-04,Single-shot polarization-resolved ultrafast mapping photography,"Single-shot ultrafast optical imaging plays a very important role in the
+detection of transient scenes, especially in capturing irreversible or
+stochastic dynamic scenes. To break the limit of time response speed of
+electronic devices, such as charge-coupled device (CCD) or complementary
+metal-oxide-semiconductor (CMOS) detectors, ultrafast optical imaging
+techniques usually convert the time information of a transient scene into the
+wavelength, angle, space or spatial frequency of the illumination light in
+previous studies. In this work, we propose a novel polarization-resolved
+ultrafast mapping photography (PUMP) technique by converting the time
+information into the polarization. Here, the spatiotemporal information of a
+dynamic scene is loaded into a rotationally polarized illumination laser pulse,
+and a polarization filtering in imaging detection and a deconvolution algorithm
+in image reconstruction are used to extract the original dynamic scene. In our
+PUMP system, the temporal resolution is 850 fs, the spatial resolution is 28.5
+lp/mm at 700 micrometer by 700 micrometer field of view, and the number of
+frames is 16. By using PUMP, a spatiotemporal dynamics of femtosecond laser
+ablation in an indium tin oxide film on glass substrate is successfully
+captured. PUMP provides a new solution for measuring the transient scenes in a
+snapshot, which will bring a very wide range of applications in the field of
+ultrafast science.",2302.02100v1
+2022-12-17,The role of plasma-activated water on the growth of freshwater algae Chlorella Pyrenoidosa and Chlorella Sorokiniana,"In the present work we have conducted two studies. In the first study, we
+investigated the role of plasma-activated water (PAW) in algae growth
+inhibition and in the second study, efforts are made to understand the role of
+PAW as a nitrogen source for algae growth enhancement. Two freshwater algae
+species are selected for the present study named Chlorella Pyrenoidosa and
+Chlorella Sorokiniana. The PAW is prepared using a pencil plasma jet and air as
+a plasma forming gas. The plasma is characterized electrically and
+identification of generated species in plasma is carried out using optical
+emission spectroscopy. The study clearly indicated that more oxidizing PAW
+exhibits algicidal effect. The PAW treatment with both the algae species
+substantially decreased their growth compared to control. Moreover, the
+morphology of algae cells showed damage and cells structure get ruptured after
+PAW treatment. In the second study, a less reactive PAW (low oxidizing
+potential) used as a nitrogen replacement in Bolds Basal Medium. The PAW-grown
+Chlorella Pyrenoidosa and Chlorella Sorokiniana showed higher growth compared
+to control. Also, a higher concentration of chlorophyll a and b, sugar, and
+protein observed compared to control. Further, we observed lower antioxidant
+enzymatic activities in PAW-grown algae compared to control. In conclusion, the
+PAW has algicidal efficacy as well as can be used as nitrogen source in
+aquaculture to enhance algae growth.",2302.07102v1
+2023-02-20,Combination effect of growth enhancers and carbon sources on synthesis of single-walled carbon nanotubes from solid carbon growth seeds,"In the synthesis of highly crystalline single-walled carbon nanotubes
+(SWCNTs), high growth temperatures are preferred, while the formation of
+impurity amorphous carbon (a-C) causes the termination of SWCNT growth and
+degrades its properties. To remove this by-product, H2O and CO2 have been
+employed in metal-catalyzed SWCNT growth systems because of their oxidizing
+ability. Recently, nonmetallic nanoparticles have become one of the growth seed
+candidates because of their high melting points and fewer metal impurities. In
+this study, by using nanodiamond-derived carbon nanoparticles as the solid
+growth seeds, we investigated the effect of CO2 and H2O on high-temperature
+SWCNT growth with two types of carbon-source supplies: C2H2 and C2H4. In this
+growth system, H2O showed oxidizing ability to etch a-C with either carbon
+sources. CO2 exhibited a similar a-C formation-preventing role in C2H4-supplied
+growth and achieved higher-purity SWCNTs with higher concentration of C2H4 than
+the case of H2O. However, in contrast to the other combinations, CO2 injection
+in the C2H2-supplied growth significantly enhanced the formation of a-C rather
+than the removal of it while the yield of SWCNTs was also increased, indicating
+the occurrence of the dehydration reaction between CO2 and C2H2. The present
+findings will lead to efficient growth of high-quality SWCNTs from nonmetallic
+growth seeds with the use of growth enhancers.",2302.09950v2
+2023-02-23,Employing High-temperature-grown SrZrO$_3$ Buffer to Enhance the Electron Mobility in La:BaSnO$_3$-based Heterostructures,"We report a synthetic route to achieve high electron mobility at room
+temperature in epitaxial La:BaSnO$_3$/SrZrO$_3$ heterostructures prepared on
+several oxide substrates. Room-temperature mobilities of 157, 145, and 143
+cm$^2$V$^{-1}$s$^{-1}$ are achieved for heterostructures grown on DyScO$_3$
+(110), MgO (001), and TbScO$_3$ (110) crystalline substrates, respectively.
+This is realized by first employing pulsed laser deposition to grow at very
+high temperature the SrZrO$_3$ buffer layer to reduce dislocation density in
+the active layer, then followed by the epitaxial growth of an overlaying
+La:BaSnO$_3$ active layer by molecular-beam epitaxy. Structural properties of
+these heterostructures are investigated, and the extracted upper limit of
+threading dislocations is well below $1.0\times 10^{10}$cm$^{-2}$ for buffered
+films on DyScO$_3$, MgO, and TbScO$_3$ substrates. The present results provide
+a promising route towards achieving high mobility in buffered La:BaSnO$_3$
+films prepared on most, if not all, oxide substrates with large compressive or
+tensile lattice mismatches to the film.",2302.12323v3
+2023-02-22,Oxidized organic molecules in the tropical free troposphere over Amazonia,"New particle formation (NPF) in the tropical free troposphere (FT) is a
+globally important source of cloud condensation nuclei, affecting cloud
+properties and climate. Oxidized organic molecules (OOMs) produced from
+biogenic volatile organic compounds are believed to contribute to aerosol
+formation in the tropical FT, but without direct chemical observations. We
+performed in-situ molecular-level OOMs measurements at the Bolivian station
+Chacaltaya at 5240 meters above sea level, on the western edge of Amazonia. For
+the first time, we demonstrate the presence of OOMs, mainly with 4-5 carbon
+atoms, simultaneously in both gas and particulate phases in tropical FT air
+from Amazonia. These observations, combined with air mass history analyses,
+indicate that the observed OOMs are linked to isoprene emitted from the
+rainforests hundreds of kilometers away. Based on particle-phase measurements,
+we find that these compounds can contribute to the growth of newly formed
+particles, and are potentially crucial for new particle formation in the
+tropical free troposphere on a continental scale. Our study will thus improve
+the understanding of aerosol formation process in the tropics.",2302.14054v1
+2023-02-28,New chondritic bodies identified in eight oxygen-bearing white dwarfs,"We present observations and analyses of eight white dwarf stars that have
+accreted rocky material from their surrounding planetary systems. The spectra
+of these helium-atmosphere white dwarfs contain detectable optical lines of all
+four major rock-forming elements (O, Mg, Si, Fe). This work increases the
+sample of oxygen-bearing white dwarfs with parent body composition analyses by
+roughly thirty-three percent. To first order, the parent bodies that have been
+accreted by the eight white dwarfs are similar to those of chondritic
+meteorites in relative elemental abundances and oxidation states. Seventy-five
+percent of the white dwarfs in this study have observed oxygen excesses
+implying volatiles in the parent bodies with abundances similar to those of
+chondritic meteorites. Three white dwarfs have oxidation states that imply more
+reduced material than found in CI chondrites, indicating the possible detection
+of Mercury-like parent bodies, but are less constrained. These results
+contribute to the recurring conclusion that extrasolar rocky bodies closely
+resemble those in our solar system, and do not, as a whole, yield unusual or
+unique compositions.",2303.00063v1
+2023-03-02,Subgap spectroscopy along hybrid nanowires by nm-thick tunnel barriers,"Tunneling spectroscopy is widely used to examine the subgap spectra in
+semiconductor-superconductor nanostructures when searching for Majorana zero
+modes (MZMs). Typically, semiconductor sections controlled by local gates at
+the ends of hybrids serve as tunnel barriers. Besides detecting states only at
+the hybrid ends, such gate-defined tunnel probes can cause the formation of
+non-topological subgap states that mimic MZMs. Here, we develop an alternative
+type of tunnel probes to overcome these limitations. After the growth of an
+InSb-Al hybrid nanowire, a precisely controlled in-situ oxidation of the Al
+shell is performed to yield a nm-thick Al oxide layer. In such thin isolating
+layer, tunnel probes can be arbitrarily defined at any position along the
+hybrid nanowire by shadow-wall angle-deposition of metallic leads. This allows
+us to make multiple tunnel probes along single nanowire hybrids and to
+successfully identify Andreev bound states (ABSs) of various spatial extension
+residing along the hybrids.",2303.00903v1
+2023-03-07,The potential of retrofitting existing coal power plants: a case study for operation with green iron,"Storing electrical energy for long periods and transporting it over long
+distances is an essential task of the necessary transition to a CO$_2$-free
+energy economy. An oxidation-reduction cycle based on iron and its oxides
+represents a very promising technology in this regard. The present work
+assesses the potential of converting an existing modern coal-fired power plant
+to operation with iron. For this purpose, a systematic retrofit study is
+carried out, employing a model that balances all material and energy fluxes in
+a state-of-the-art coal-fired power plant. Particular attention is given to
+components of the burner system and the system$'$s heat exchanger. The analysis
+provides evidence that main components such as the steam generator and steam
+cycle can be reused with moderate modifications. Major modifications are
+related to the larger amounts of solids produced during iron combustion, for
+instance in the particle feeding and removal systems. Since the high particle
+densities and lower demand for auxiliary systems improve the heat transfer, the
+net efficiencies of iron operation can be one to two percentage points better
+than coal operation, depending on operating conditions. This new insight can
+significantly accelerate the introduction of this innovative technology by
+guiding future research and the development of the retrofit option.",2303.04000v2
+2023-03-15,Accurate determination of band tail properties in amorphous semiconductor thin film with Kelvin Probe Force Microscopy,"Amorphous oxide semiconductors are receiving significant attention due to
+their relevance for large area electronics. Their disordered microscopic
+structure causes the formation of band tails in the density of states (DOS)
+that strongly affect charge transport properties. Bandtail properties are
+crucial to understand for optimizing thin film device performance. Among the
+available techniques to measure the DOS, KPFM is exceptional as it enables
+precise local electronic investigations combined with microscopic imaging.
+However, a model to interpret KPFM spectroscopy data on amorphous
+semiconductors of finite thickness is lacking. To address this issue, we
+provide an analytical solution to the Poisson's equation for a
+metal-insulator-semiconductor (MIS) junction interacting with the AFM tip. The
+solution enables us to fit experimental data for semiconductors with finite
+thickness and obtain the DOS parameters, such as band tail width (E_t), doping
+density (N_D), and flat band potential. To demonstrate our method, we perform
+KPFM experiments on Indium-Gallium-Zinc Oxide (IGZO) thin film transistors
+(IGZO-TFTs). DOS parameters compare well to values obtained with photocurrent
+spectroscopy. We demonstrate the potentials of the developed method by
+investigating the impact of ionizing radiation on DOS parameters and TFT
+performance. Our results provide clear evidence that the observed shift in
+threshold voltage is caused by static charge in the gate dielectric leading to
+a shift in flat band potential. Band-tails and doping density are not affected
+by the radiation. The developed methodology can be easily translated to
+different semiconductor materials and paves the way towards quantitative
+microscopic mapping of local DOS parameters in thin film devices.",2303.08442v1
+2023-03-27,PiNNwall: Heterogeneous Electrode Models from Integrating Machine Learning and Atomistic Simulation,"Electrochemical energy storage always involves the capacitive process. The
+prevailing electrode model used in the molecular simulation of polarizable
+electrode-electrolyte systems is the Siepmann-Sprik model developed for perfect
+metal electrodes. This model has been recently extended to study the
+metallicity in the electrode by including the Thomas-Fermi screening length.
+Nevertheless, a further extension to heterogeneous electrode models requires
+introducing chemical specificity, which does not have any analytical recipes.
+Here, we address this challenge by integrating the atomistic machine learning
+code (PiNN) for generating the base charge and response kernel and the
+classical molecular dynamics code (MetalWalls) dedicated to the modeling of
+electrochemical systems, and this leads to the development of the PiNNwall
+interface. Apart from the cases of chemically doped graphene and graphene oxide
+electrodes as shown in this study, the PiNNwall interface also allows us to
+probe polarized oxide surfaces in which both the proton charge and the
+electronic charge can coexist. Therefore, this work opens the door for modeling
+heterogeneous and complex electrode materials often found in energy storage
+systems.",2303.15307v4
+2023-04-03,Supercontinuum generation in dispersion engineered highly doped silica glass waveguides,"We investigate the effect of a lower index oxide layer inclusion within a
+highly doped silica glass slot waveguide for optimized supercontinuum
+generation at telecom wavelengths. By controlling the thickness of the oxide
+slot, we demonstrate that one can engineer the waveguide dispersion profile so
+that to obtain supercontinua with vastly different spectral broadening dynamics
+and bandwidths. Using this approach, we designed and fabricated a waveguide
+with a low and flat dispersion profile of less than 43 ps/km/nm across a
+wavelength range spanning over 1000 nm. We show that, when pumped at the
+telecom C-band, we can generate a supercontinuum that spans over 1.5 octave,
+from approximately 817 nm to 2183 nm. The numerical simulations, whose
+parameters are derived from the measured waveguide dimension and material
+indices, exhibit good agreement with experimental measurements, where one can
+observe both a qualitative and quantitative match in the supercontinuum overall
+spectrum and specific features (e.g. soliton and dispersive wave locations).
+This study represents an important step forward in the control and manipulation
+of dispersive and nonlinear dynamics in highly doped silica glass waveguides,
+paving the way towards advanced on-chip broadband light manipulation.",2304.00800v1
+2023-04-05,Identification of high-reliability regions of machine learning predictions in materials science using transparent conducting oxides and perovskites as examples,"Progress in the application of machine learning (ML) methods to materials
+design is hindered by the lack of understanding of the reliability of ML
+predictions, in particular for the application of ML to small data sets often
+found in materials science. Using ML prediction for transparent conductor oxide
+formation energy and band gap, dilute solute diffusion, and perovskite
+formation energy, band gap and lattice parameter as examples, we demonstrate
+that 1) analysis of ML results by construction of a convex hull in feature
+space that encloses accurately predicted systems can be used to identify
+regions in feature space for which ML predictions are highly reliable 2)
+analysis of the systems enclosed by the convex hull can be used to extract
+physical understanding and 3) materials that satisfy all well-known chemical
+and physical principles that make a material physically reasonable are likely
+to be similar and show strong relationships between the properties of interest
+and the standard features used in ML. We also show that similar to the
+composition-structure-property relationships, inclusion in the ML training data
+set of materials from classes with different chemical properties will not be
+beneficial and will slightly decrease the accuracy of ML prediction and that
+reliable results likely will be obtained by ML model for narrow classes of
+similar materials even in the case where the ML model will show large errors on
+the dataset consisting of several classes of materials. Our work suggests that
+analysis of the error distributions of ML predictions will be beneficial for
+the further development of the application of ML methods in material science.",2304.02218v1
+2023-04-07,Comparative analysis of five NH$_3$/air oxidation mechanisms,"Five recently developed chemical kinetics mechanisms for ammonia oxidation
+are analysed and compared, in the context of homogeneous adiabatic
+autoignition. The analysis focuses on the ignition delay and is based on the
+explosive mode that is shown to drive the process. Using algorithmic tools
+based on the Computational Singular Perturbation algorithm, the reactions
+responsible for the generation of the explosive mode are identified, along with
+the variables (species mass fractions and temperature) that associate the most
+to this mode. Comparison of these sets of reactions and variables, obtained for
+each mechanism, allows to correlate the differences in the predictive outcomes
+from the mechanisms with specific reactions. The major differences identified,
+which lead to different ignition delay times, relate to (i) the relative
+duration of chemical and thermal runaways (a sizeable chemical runaway develops
+only in some mechanisms) and (ii) the dominant chemistry during the chemical
+runaway (chemistry involving species with two nitrogen atoms is active only in
+some mechanisms). The major similarities identified refer to the thermal
+runaway and in particular to (i) the chemical activity, which is supported
+mainly by OH-producing reactions and by reactions producing their reactants and
+(ii) the thermal activity, which is dominated by strongly exothermic
+OH-consuming reactions.",2304.03549v1
+2023-04-13,Importance of the catalytic effect of the substrate in the functionality of lubricant additives: the case of MoDTC,"Molybdenum dithiocarbamates (MoDTCs) are lubricant additives very efficient
+in reducing the friction of steel and they are employed in a number of
+industrial applications. The functionality of these additives is ruled by the
+chemical interactions occurring at the buried sliding interface, which are of
+key importance for the improvement of the lubrication performance. Yet, these
+tribochemical processes are very difficult to monitor in real time. Ab initio
+molecular dynamics simulations are the ideal tool to shed light into such a
+complicated reactivity. In this work we perform ab initio simulations, both in
+static and tribological conditions, to understand the effect of surface
+oxidation on the tribochemical reactivity of MoDTC and we find that when the
+surfaces are covered by oxygen, the first dissociative steps of the additives
+are significantly hindered. Our preliminary tribological tests on oxidized
+steel discs support these results. Bare metallic surfaces are necessary for a
+stable adsorption of the additives, their quick decomposition, and the
+formation of a durable MoS$_2$ tribolayer. This work demonstrates the
+importance of the catalytic role of the substrate and confirms the full
+capability of the computational protocol in the pursuit of materials and
+compounds more efficient in reducing friction.",2304.06462v2
+2023-04-15,Thermal Reconversion of Oxidised Lead White in Mural Paintings via a Massicot Intermediate,"Lead white is the most ancient and common white pigment used in mural
+paintings. However, it tends to blacken with time due to its oxidation to
+plattnerite (\b{eta}-PbO2). Chemical treatments were used but they can put the
+pictorial layers supports at risks. Hereby we address the possibility of
+thermally reconverting black plattnerite to white lead carbonates via a
+massicot (\b{eta}-PbO) intermediate, with a view to developing a restoration
+procedure using continuous wave laser heating. We first investigated the
+conditions (temperature, time, and environment) in which pure powders react,
+before studying mural painting samples. Experiments were made in ovens and TGA
+and XRD and SEM characterization were achieved. Litharge ({\alpha}-PbO) and
+massicot were obtained from plattnerite respectively between 564 and 567
+{\deg}C and at 650 {\deg}C. Lead carbonates (cerussite, hydrocerussite and
+plumbonacrite) formed from massicot in wet CO2 below 100 {\deg}C in a few
+hours. Lastly, when heating plattnerite based mural painting samples, lead
+species reacted with binders and mortar, yielding massicot, plumbonacrite but
+also lead silicate and calcium lead oxides. This demonstrates the viability of
+thermal reconversion of darkened lead in mural, while raising concerns about
+the formation of several lead species by reaction with mural painting
+constituents.",2304.07541v1
+2023-04-27,Graphene-Based Transparent Flexible Strain Gauges with Tunable Sensitivity and Strain Range,"Flexible strain gauges with 88% optical transmittance, of reduced graphene
+oxide (rGO) on poly dimethylsiloxne membranes, are produced form monolayers of
+graphene oxide assembled into densely packed sheets at an immiscible
+hexane/water interface and subsequently reduced in HI vapor to increase
+electrical conductivity. Pre-straining and relaxing the membranes introduces a
+population of cracks into the rGO film. Subsequent straining opens these
+cracks, inducing piezoresistivity. Reduction for 30 s forms an array of
+parallel cracks that do not individually span the membrane and results in a
+strain gauge with a usable strain range > 0.2 and gauge factor of 20 - 100 at
+low strain levels that increases with increasing pre-strain. In all cases the
+gauge facto decreases with increasing applied strain and asymptotes to a value
+of about 3, as it approaches the pre-strain value. If the rGO is reduced for 60
+s, the cracks fully span the width of the membrane, leading to an increased
+gauge resistance but a much more sensitive strain gauge with GF ranging from
+1000 - 16000. However, the usable strain range reduces to < 0.01. A simple
+equivalent resistor model is proposed to describe the behaviour of both gauge
+types. The gauges show a repeatable and stable response with loading
+frequencies up to 1 kHz and have been used to detect human body motion in a
+simple e-skin demonstration.",2304.14297v2
+2023-04-28,Anisotropic Electronic Structure of the Two-Dimensional Electron Gas at the AlOx/KTaO3(110) interface,"Oxide-based two-dimensional electron gases (2DEGs) have generated significant
+interest due to their potential for discovering novel physical properties.
+Among these, 2DEGs formed in KTaO3 stand out due to the recently discovered
+crystal face-dependent superconductivity and large Rashba splitting, both of
+which hold potential for future oxide electronics devices. In this work,
+angle-resolved photoemission spectroscopy is used to study the electronic
+structure of the 2DEG formed at the (110) surface of KTaO3 after deposition of
+a thin Al layer. Our experiments revealed a remarkable anisotropy in the
+orbital character of the electron-like dispersive bands, which form a Fermi
+surface consisting of two elliptical contours with their major axes
+perpendicular to each other. The measured electronic structure is used to
+constrain the modeling parameters of self-consistent tight-binding slab
+calculations of the band structure. In these calculations, an anisotropic
+Rashba splitting is found with a value as large as 4 meV at the Fermi level
+along the [-110] crystallographic direction. This large unconventional and
+anisotropic Rashba splitting is rationalized based on the orbital angular
+momentum formulation. These findings provide insights into the interpretation
+of spin-orbitronics experiments and help to constrain models for
+superconductivity in the KTO(110)-2DEG system.",2304.14805v1
+2023-05-04,Accelerated Screening of Ternary Chalcogenides for High-Performance Optoelectronic Materials,"Chalcogenides, which refer to chalcogen anions, have attracted considerable
+attention in multiple fields of applications, such as optoelectronics,
+thermoelectrics, transparent contacts, and thin film transistors. In comparison
+to oxide counterparts, chalcogenides have demonstrated higher mobility and
+\textit{p}-type dopability, owing to larger orbital overlaps between metal-X
+covalent chemical bondings and higher-energy valence bands derived by
+p-orbitals. Despite the potential of chalcogenides, the number of successfully
+synthesized compounds remains relatively low compared to oxides, suggesting the
+presence of numerous unexplored chalcogenides with fascinating physical
+characteristics. In this study, we implemented a systematic high-throughput
+screening process combined with first-principles calculations on ternary
+chalcogenides using 34 crystal structure prototypes. We generated a
+computational material database containing over 400,000 compounds by exploiting
+the ion-substitution approach at different atomic sites with elements in the
+periodic table. The thermodynamic stabilities of the candidates were validated
+using the chalcogenides included in the Open Quantum Materials Database.
+Moreover, we trained a model based on Crystal Graph Convolutional Neural
+Networks to predict the thermodynamic stability of novel materials.
+Furthermore, we theoretically evaluated the electronic structures of the stable
+candidates using accurate hybrid functionals. A series of in-depth
+characteristics, including the carrier effective masses, electronic
+configuration, and photovoltaic conversion efficiency, was also investigated.
+Our work provides useful guidance for further experimental research in the
+synthesis and characterization of such chalcogenides as promising candidates,
+as well as charting the stability and optoelectronic performance of ternary
+chalcogenides.",2305.02634v1
+2023-05-09,Atomic Layer Deposited Protective Coating of Aluminum Oxide on Silver-based Telescope Mirror A Comparison Between a Pure Ozone and H2O Precursor,"Although silver-based telescope mirrors excel over other materials such as
+gold and aluminum in the visible-infrared spectral range, they require robust
+protective coatings to overcome their inherent low durability. Our research
+shows that a single-layer of aluminum oxide (AlOx) deposited through thermal
+atomic layer deposition (ALD) using trimethylaluminum (TMA) and water (H2O) at
+low temperatures (~60{\deg}C) serves as an acceptable protective coating
+without adversely impacting the optical performance of the mirrors. While
+silver-based mirrors protected with a single-layer of AlOx perform decently in
+the field, in environmental tests under high-humidity at high-temperature
+conditions that accelerate underlying failure mechanisms, they degrade quickly,
+suggesting that there is room for improvement. This paper describes a study
+that compares the performance and endurance of two sets of silver-based mirrors
+protected by a single-layer of AlOx prepared by thermal ALD with two types of
+oxygen precursors: H2O and pure ozone (PO). The study shows that while the two
+types of samples, regardless of their oxygen precursors, initially have
+comparable spectral reflectance, the reflectance of the samples with AlOx
+protective coatings prepared with PO remain nearly constant 1.6 times longer
+than those with AlOx protective coatings prepared with H2O in the environmental
+test, suggesting promising characteristics of AlOx protective coatings prepared
+with PO.",2305.05109v1
+2023-05-21,Head-to-Head and Tail-to-Tail Domain Wall in Hafnium Zirconium Oxide: A First Principles Analysis of Domain Wall Formation and Energetics,"180{\deg} domains walls (DWs) of Head-to-Head/Tail-to-Tail (H-H/T-T) type in
+ferroelectric (FE) materials are of immense interest for a comprehensive
+understanding of the FE attributes as well as harnessing them for new
+applications. Our first principles calculation suggests that such DW formation
+in Hafnium Zirconium Oxide (HZO) based FEs depends on the unique attributes of
+the HZO unit cell, such as polar-spacer segmentation. Cross pattern of the
+polar and spacer segments in two neighboring domains along the polarization
+direction (where polar segment of one domain aligns with the spacer segment of
+another) boosts the stability of such DWs. We further show that low density of
+oxygen vacancies at the metal-HZO interface and high work function of metal
+electrodes are conducive for T-T DW formation. On the other hand, high density
+of oxygen vacancy and low work function of metal electrode favor H-H DW
+formation. Polarization bound charges at the DW get screened when band bending
+from depolarization field accumulates holes (electrons) in T-T (H-H) DW. For a
+comprehensive understanding, we also investigate their FE nature and domain
+growth mechanism. Our analysis suggests that a minimum thickness criterion of
+domains has to be satisfied for the stability of H-H/T-T DW and switching of
+the domains through such DW formation.",2305.12350v2
+2023-05-31,Monofluorinated Ether Electrolyte with Acetal Backbone for High-Performance Lithium Metal Batteries,"High degree of fluorination for ether electrolytes has resulted in improved
+cycling stability of lithium metal batteries (LMBs) due to stable SEI formation
+and good oxidative stability. However, the sluggish ion transport and
+environmental concerns of high fluorination degree drives the need to develop
+less fluorinated structures. Here, we introduce bis(2-fluoroethoxy)methane
+(F2DEM) which features monofluorination of the acetal backbone. High coulombic
+efficiency (CE) and stable long-term cycling in Li||Cu half cells can be
+achieved with F2DEM even under fast Li metal plating conditions. The
+performance of F2DEM is further compared with diethoxymethane (DEM) and
+2-[2-(2,2-Difluoroethoxy)ethoxy]-1,1,1-Trifluoroethane (F5DEE). The structural
+similarity of DEM allows us to better probe the effects of monofluorination,
+while F5DEE is chosen as the one of the best performing LMB electrolytes for
+reference. The monofluorine substitution provides improved oxidation stability
+compared to non-fluorinated DEM, as demonstrated in the linear sweep
+voltammetry (LSV) and voltage holding experiments in Li||Pt and Li||Al cells.
+Higher ionic conductivity compared to F5DEE is also observed due to the
+decreased degree of fluorination. Furthermore, 1.75 M lithium
+bis(fluorosulfonyl)imide (LiFSI) / F2DEM displays significantly lower
+overpotential compared with the two reference electrolytes, which improves
+energy efficiency and enables its application in high-rate conditions.
+Comparative studies of F2DEM with DEM and F5DEE in anode-free (LiFePO4) LFP
+pouch cells and high-loading LFP coin cells with 20 {\mu}m excess Li further
+show improved capacity retention of F2DEM electrolyte.",2305.19580v1
+2023-06-19,Ion Intercalation in Lanthanum Strontium Ferrite for Aqueous Electrochemical Energy Storage Devices,"Ion intercalation of perovskite oxides in liquid electrolytes is a very
+promising method for controlling their functional properties while storing
+charge, which opens the potential application in different energy and
+information technologies. Although the role of defect chemistry in the oxygen
+intercalation in a gaseous environment is well established, the mechanism of
+ion intercalation in liquid electrolytes at room temperature is poorly
+understood. In this study, the defect chemistry during ion intercalation of
+La0.5Sr0.5FeO3-{\delta} thin films in alkaline electrolytes is studied. Oxygen
+and proton intercalation into the LSF perovskite structure is observed at
+moderate electrochemical potentials (0.5 V to -0.4 V), giving rise to a change
+in the oxidation state of Fe (as a charge compensation mechanism). The
+variation of the concentration of holes as a function of the intercalation
+potential was characterized by in-situ ellipsometry and the concentration of
+electron holes was indirectly quantified for different electrochemical
+potentials. Finally, a dilute defect chemistry model that describes the
+variation of defect species during ionic intercalation was developed.",2306.10887v1
+2023-06-22,Dynamic Versus Static Oxidation of Nb/Al-AlO$_x$/Nb Trilayer,"High quality Nb-based superconductor-insulator-superconductor (SIS) junctions
+with Al oxide (AlO$_x$) tunnel barriers grown from Al overlayers are widely
+reported in the literature. However, the thin barriers required for high
+critical current density (J$_c$) junctions exhibit defects that result in
+significant subgap leakage current that is detrimental for many applications.
+High quality, high-J$_c$ junctions can be realized with AlN$_x$ barriers, but
+control of J$_c$ is more difficult than with AlO$_x$. It is therefore of
+interest to study the growth of thin AlO$_x$ barriers with the ultimate goal of
+achieving high quality, high-J$_c$ AlO$_x$ junctions. In this work, 100\%\
+O$_2$ and 2\%\ O$_2$ in Ar gas mixtures are used both statically and
+dynamically to grow AlO$_x$ tunnel barriers over a large range of oxygen
+exposures. In situ ellipsometry is used for the first time to extensively
+measure AlO$_x$ tunnel barrier growth in real time, revealing a number of
+unexpected patterns. Finally, a set of test junction wafers was fabricated that
+exhibited the well-known dependence of J$_c$ on oxygen exposure (E) in order to
+further validate the experimental setup.",2306.12684v1
+2023-06-23,Correlating activity and defects in (photo)electrocatalysts using in-situ transient optical microscopy,"(Photo)electrocatalysts capture sunlight and use it to drive chemical
+reactions such as water splitting to produce H2. A major factor limiting
+photocatalyst development is their large heterogeneity which spatially
+modulates reactivity and precludes establishing robust structure-function
+relationships. To make such links requires simultaneously probing of the
+electrochemical environment at microscopic length scales (nm to um) and broad
+timescales (ns to s). Here, we address this challenge by developing and
+applying in-situ steady-state and transient optical microscopies to directly
+map and correlate local electrochemical activity with hole lifetimes, oxygen
+vacancy concentration and the photoelectrodes crystal structure. Using this
+combined approach alongside spatially resolved X-Ray absorption measurements,
+we study microstructural and point defects in prototypical hematite (Fe2O3)
+photoanodes. We demonstrate that regions of Fe2O3, adjacent to microstructural
+cracks have a better photoelectrochemical response and reduced back electron
+recombination due to an optimal oxide vacancy concentration, with the film
+thickness and carbon impurities also dramatically influencing activity in a
+complex manner. Our work highlights the importance of microscopic mapping to
+understand activity and the impact of defects in even, seemingly, homogeneous
+solid-state metal oxide photoelectrodes.",2306.13401v1
+2023-06-26,Atomic-Scale Tailoring of Chemisorbed Atomic Oxygen on Epitaxial Graphene for Graphene-Based Electronic Devices,"Graphene, with its unique band structure, mechanical stability, and high
+charge mobility, holds great promise for next-generation electronics.
+Nevertheless, its zero band gap challenges the control of current flow through
+electrical gating, consequently limiting its practical applications. Recent
+research indicates that atomic oxygen can oxidize epitaxial graphene in a
+vacuum without causing unwanted damage. In this study, we have investigated the
+effects of chemisorbed atomic oxygen on the electronic properties of epitaxial
+graphene, using scanning tunneling microscopy (STM). Our findings reveal that
+oxygen atoms effectively modify the electronic states of graphene, resulting in
+a band gap at its Dirac point. Furthermore, we demonstrate that it is possible
+to selectively induce desorption or hopping of oxygen atoms with atomic
+precision by applying appropriate bias sweeps with an STM tip. These results
+suggest the potential for atomic-scale tailoring of graphene oxide, enabling
+the development of graphene-based atomic-scale electronic devices.",2306.14501v1
+2023-06-27,Numerical study of nitrogen oxides chemistry during plasma assisted combustion in a sequential combustor,"Plasma Assisted Combustion (PAC) is a promising technology to enhance the
+combustion of lean mixtures prone to instabilities and flame blow-off. Although
+many PAC experiments demonstrated combustion enhancement, several studies
+report an increase in NOx emissions. The aim of this study is to determine the
+kinetic pathways leading to NOx formation in the second stage of a sequential
+combustor assisted by Nanosecond Repetitively Pulsed Discharges (NRPDs). For
+this purpose, Large Eddy Simulation (LES) associated with an accurate
+description of the combustion/NOx chemistry and a phenomenological model of the
+plasma kinetics is used. Detailed kinetics 0-Dimensional reactors complement
+the study. First, the LES setup is validated by comparison with experiments.
+Then, the NOx chemistry is analyzed. For the conditions of operation studied,
+it is shown that the production of atomic nitrogen in the plasma by direct
+electron impact on nitrogen molecules increases the formation of NO. Then, the
+NO molecules are transported through the turbulent flame without being strongly
+affected. This study illustrates the need to limit the diatomic nitrogen
+dissociation process in order to mitigate harmful emissions. More generally,
+the very good agreement with experimental measurements demonstrates the
+capability of LES combined with accurate models to predict the NRPD effects on
+both turbulent combustion and NOx emissions.",2306.15539v1
+2023-06-29,Ion-beam sputtering of NiO hole transporting layers for p-i-n halide perovskite solar cells,"Ion-beam sputtering offers significant benefits in terms of deposition
+uniformity and pinhole-free thin-films without limiting the scalability of the
+process. In this work, the reactive ion-beam sputtering of nickel oxide has
+been developed for the hole transporting layer of a p-i-n perovskite solar
+cells (PCSs). The process is carried out by oxidation of the scattered Ni
+particles with additional post-treatment annealing regimes. Using deposition
+rate of 1.2 nm/min allowed growth of very uniform NiO coating with the
+roughness below 0.5 nm on polished Si wafer (15x15 cm2). We performed a complex
+investigation of structural, optical, surface and electrical properties of the
+NiO thin-films. The post-treatment annealing (150-300C) was considered as an
+essential process for improvement of the optical transparency, decrease of
+defects concentration and gain of the charge carrier mobility. As result, the
+annealed ion-beam sputtered NiO films delivered a power conversion efficiency
+(PCE) up to 20.14%, while device without post-treatment reached the value of
+11.84%. The improvement of the output performance originated from an increase
+of the short-circuit current density (Jsc), open circuit voltage (Voc), shunt
+and contact properties in the devices. We also demonstrate that the ion-beam
+sputtering of NiO can be successfully implemented for the fabrication of large
+area modules (54.5 cm2) and PSCs on a flexible plastic substrate (125 microns).",2306.16949v1
+2023-07-14,Interpretable machine learning to understand the performance of semi local density functionals for materials thermochemistry,"This study investigates the use of machine learning (ML) to correct the
+enthalpy of formation (Hf) from two separate DFT functionals, PBE and SCAN, to
+the experimental Hf across 1011 solid-state compounds. The ML model uses a set
+of 25 properties that characterize the electronic structure as calculated using
+PBE and SCAN. The ML model significantly decreases the error in PBE-calculated
+Hf values from an mean absolute error (MAE) of 195 meV/atom to an MAE = 80
+meV/atom when compared to the experiment. For PBE, the PDP+GAM analysis shows
+compounds with a high ionicity (I), i.e., I>0.22, have errors in Hf that are
+twice as large as compounds having I < 0.22 (246 meV/atom compared to 113
+meV/atom). Conversely, no analogous trend is observed for SCAN-calculated Hfs,
+which explains why the ML model for PBE can more easily correct the systematic
+error in calculated Hfs for PBE but not for SCAN. Although the literature
+suggests PBE is reliable for intermetallics but less so for oxides and halides,
+our analysis reveals intermetallics pose a challenge for PBE only when the
+charge transfer is significant (I >0.22). Meanwhile, oxides and halides may be
+described accurately by PBE for systems in which charge transfer is relatively
+low (I < 0.22).",2307.07609v1
+2023-07-19,Origin of Life Molecules in the Atmosphere After Big Impacts on the Early Earth,"The origin of life on Earth would benefit from a prebiotic atmosphere that
+produced nitriles, like HCN, which enable ribonucleotide synthesis. However,
+geochemical evidence suggests that Hadean air was relatively oxidizing with
+negligible photochemical production of prebiotic molecules. These paradoxes are
+resolved by iron-rich asteroid impacts that transiently reduced the entire
+atmosphere, allowing nitriles to form in subsequent photochemistry. Here, we
+investigate impact-generated reducing atmospheres using new time-dependent,
+coupled atmospheric chemistry and climate models, which account for gas-phase
+reactions and surface-catalysis. The resulting H$_2$-, CH$_4$- and NH$_3$-rich
+atmospheres persist for millions of years, until hydrogen escapes to space. HCN
+and HCCCN production and rainout to the surface can reach $10^9$ molecules
+cm$^{-2}$ s$^{-1}$ in hazy atmospheres with a mole ratio of $\mathrm{CH_4} /
+\mathrm{CO_2} > 0.1$. Smaller $\mathrm{CH_4} / \mathrm{CO_2}$ ratios produce
+HCN rainout rates $< 10^5$ molecules cm$^{-2}$ s$^{-1}$, and negligible HCCCN.
+The minimum impactor mass that creates atmospheric $\mathrm{CH_4} /
+\mathrm{CO_2} > 0.1$ is $4 \times 10^{20}$ to $5 \times 10^{21}$ kg (570 to
+1330 km diameter), depending on how efficiently iron reacts with a steam
+atmosphere, the extent of atmospheric equilibration with an impact-induced melt
+pond, and the surface area of nickel that catalyzes CH$_4$ production.
+Alternatively, if steam permeates and deeply oxidizes crust, impactors $\sim
+10^{20}$ kg could be effective. Atmospheres with copious nitriles have $> 360$
+K surface temperatures, perhaps posing a challenge for RNA longevity, although
+cloud albedo can produce cooler climates. Regardless, post-impact cyanide can
+be stockpiled and used in prebiotic schemes after hydrogen has escaped to
+space.",2307.09761v1
+2023-07-31,Enhanced Nonlinearity of Epsilon-Near-Zero Indium Tin Oxide Nanolayers with Tamm Plasmon-Polariton States,"Recently, materials with vanishingly small permittivity, known as
+epsilon-near-zero (ENZ) media, emerged as promising candidates to achieve
+nonlinear optical effects of unprecedented magnitude on a solid-state platform.
+In particular, the ENZ behavior of Indium Tin Oxide (ITO) thin films resulted
+in Kerr-type nonlinearity with non-perturbative refractive index variations
+that are key to developing more efficient Si-compatible devices with
+sub-wavelength dimensions such as all-optical switchers, modulators, and novel
+photon detectors. In this contribution, we propose and demonstrate enhancement
+of the nonlinear index variation of 30 nm-thick ITO nanolayers by silicon
+dioxide/silicon nitride (SiO2/SiN) Tamm plasmon-polariton structures fabricated
+by radio-frequency magnetron sputtering on transparent substrates under
+different annealing conditions. In particular, we investigate the linear and
+nonlinear optical properties of ITO thin films and resonant photonic structures
+using broadband spectroscopic ellipsometry and intensity dependent Z-scan
+nonlinear characterization demonstrating enhancement of optical nonlinearity
+with refractive index variations as large as in the non-perturbative regime.
+Our study reveals that the efficient excitation of strongly confined
+plasmon-polariton Tamm states substantially boost the nonlinear optical
+response of ITO nanolayers providing a stepping stone for the engineering of
+more efficient infrared devices and nanostructures for a broad range of
+applications including all-optical data processing, nonlinear spectroscopy,
+sensing, and novel photodetection modalities.",2308.00168v3
+2023-08-02,Permissible domain walls in monoclinic MAB ferroelectric phases,"The concept of monoclinic ferroelectric phases has been extensively used over
+recent decades for the understanding of ferroelectric materials. Monoclinic
+phases have been actively invoked to describe the phase boundaries such as
+Morphotropic Phase Boundary in functional perovskite oxides. These phases are
+believed to play the major role in the enhancement of functional properties
+such as dielectricity and electromechanical coupling through rotation of
+spontaneous polarization and modification of the rich domain microstructures.
+Unfortunately, such microstructures remain poorly understood due to the
+complexity of the subject. The goal of this work is to formulate the
+geometrical laws behind the monoclinic domain microstructures. Specifically, we
+implement the result of our previous work (Gorfman et al, 2022) to catalogue
+and outline some properties of permissible domain walls that connect strain
+domains with monoclinic (MAB type) symmetry, occurring in ferroelectric
+perovskite oxides. The term permissible (Fousek & Janovec, 1969) pertains to
+the domain walls, connecting a pair of strain domains without a lattice
+mismatch. We found that 12 monoclinic domains may form pairs connected along 84
+types of permissible domain walls. These contain 48 domain walls with fixed
+Miller indices (known as W-walls) and 36 domain walls whose Miller indices may
+change when free lattice parameters change as well (known as S-walls). We
+provide simple analytical expressions for the orientation of these domain
+walls, the matrices of transformation between crystallographic basis vectors
+and for the separation between Bragg peaks, diffracted from each of the pairs
+of domains, connected along 84 permissible domain walls. The resultscan
+contribute to the understanding and facilitate investigation of complex
+monoclinic domain microstructures.",2308.01324v3
+2023-08-08,ExoMol line lists -- LIII: Empirical Rovibronic spectra of Yttrium Oxide (YO),"Empirical line lists for the open shell molecule $^{89}$Y$^{16}$O (yttrium
+oxide) and its isotopologues are presented. The line lists cover the 6 lowest
+electronic states: $X {}^{2}\Sigma^{+}$, $A {}^{2}\Pi$, $A' {}^{2}\Delta$, $B
+{}^{2}\Sigma^{+}$, $C {}^{2}\Pi$ and $D {}^{2}\Sigma^{+}$ up to 60000 cm$^{-1}$
+($<0.167$ $\mu$m) for rotational excitation up to $J = 400.5$. An \textit{ab
+initio} spectroscopic model consisting of potential energy curves (PECs),
+spin-orbit and electronic angular momentum couplings is refined by fitting to
+experimentally determined energies of YO, derived from published YO
+experimental transition frequency data. The model is complemented by empirical
+spin-rotation and $\Lambda$-doubling curves and \textit{ab initio} dipole
+moment and transition dipole moment curves computed using MRCI. The \textit{ab
+initio} PECs computed using the complete basis set limit extrapolation and the
+CCSD(T) method with its higher quality provide an excellent initial
+approximation for the refinement. Non-adiabatic coupling curves for two pairs
+of states of the same symmetry $A$/$C$ and $B$/$D$ are computed using a
+state-averaged CASSCF and used to built diabatic representations for the $A
+{}^{2}\Pi$, $C {}^{2}\Pi$, $B {}^{2}\Sigma^{+}$ and $D {}^{2}\Sigma^{+}$
+curves. Calculated lifetimes of YO are tuned to agree well with the experiment,
+where available. The BRYTS YO line lists for are included into the ExoMol data
+base (www.exomol.com).",2308.04173v3
+2023-08-12,Polar discontinuities and interfacial electronic properties of Bi$_2$O$_2$Se on SrTiO$_3$,"The layered oxychalcogenide semiconductor Bi$_2$O$_2$Se (BOS) hosts a
+multitude of unusual properties including high electron mobility. Owing to
+similar crystal symmetry and lattice constants, the perovskite oxide SrTiO$_3$
+(STO) has been demonstrated to be an excellent substrate for wafer-scale growth
+of atomically thin BOS films. However, the structural and electronic properties
+of the BOS/STO interface remain poorly understood. Here, through
+first-principles study, we reveal that polar discontinuities and interfacial
+contact configurations have a strong impact on the electronic properties of
+ideal BOS/STO interfaces. The lowest-energy [Bi-TiO$_2$] contact type, which
+features the contact between a Bi$_2$O$_2$ layer of BOS with the
+TiO$_2$-terminated surface of STO, incurs significant interfacial charge
+transfer from BOS to STO, producing a BOS/STO-mixed, $n$-type metallic state at
+the interface. By contrast, the [Se-SrO] contact type, which is the most stable
+contact configuration between BOS and SrO-terminated STO substrate, has a much
+smaller interfacial charge transfer from STO to BOS and exhibits $p$-type
+electronic structure with much weaker interfacial hybridization between BOS and
+STO. These results indicate that BOS grown on TiO$_2$-terminated STO substrates
+could be a fruitful system for exploring emergent phenomena at the interface
+between an oxychalcogenide and an oxide, whereas BOS grown on SrO-terminated
+substrates may be more advantageous for preserving the excellent intrinsic
+transport properties of BOS.",2308.06486v1
+2023-08-14,Physics-Informed Deep Learning to Reduce the Bias in Joint Prediction of Nitrogen Oxides,"Atmospheric nitrogen oxides (NOx) primarily from fuel combustion have
+recognized acute and chronic health and environmental effects. Machine learning
+(ML) methods have significantly enhanced our capacity to predict NOx
+concentrations at ground-level with high spatiotemporal resolution but may
+suffer from high estimation bias since they lack physical and chemical
+knowledge about air pollution dynamics. Chemical transport models (CTMs)
+leverage this knowledge; however, accurate predictions of ground-level
+concentrations typically necessitate extensive post-calibration. Here, we
+present a physics-informed deep learning framework that encodes
+advection-diffusion mechanisms and fluid dynamics constraints to jointly
+predict NO2 and NOx and reduce ML model bias by 21-42%. Our approach captures
+fine-scale transport of NO2 and NOx, generates robust spatial extrapolation,
+and provides explicit uncertainty estimation. The framework fuses
+knowledge-driven physicochemical principles of CTMs with the predictive power
+of ML for air quality exposure, health, and policy applications. Our approach
+offers significant improvements over purely data-driven ML methods and has
+unprecedented bias reduction in joint NO2 and NOx prediction.",2308.07441v1
+2023-08-18,Predicting Properties of Oxide Glasses Using Informed Neural Networks,"Many modern-day applications require the development of new materials with
+specific properties. In particular, the design of new glass compositions is of
+great industrial interest. Current machine learning methods for learning the
+composition-property relationship of glasses promise to save on expensive
+trial-and-error approaches. Even though quite large datasets on the composition
+of glasses and their properties already exist (i.e., with more than 350,000
+samples), they cover only a very small fraction of the space of all possible
+glass compositions. This limits the applicability of purely data-driven models
+for property prediction purposes and necessitates the development of models
+with high extrapolation power. In this paper, we propose a neural network model
+which incorporates prior scientific and expert knowledge in its learning
+pipeline. This informed learning approach leads to an improved extrapolation
+power compared to blind (uninformed) neural network models. To demonstrate
+this, we train our models to predict three different material properties, that
+is, the glass transition temperature, the Young's modulus (at room
+temperature), and the shear modulus of binary oxide glasses which do not
+contain sodium. As representatives for conventional blind neural network
+approaches we use five different feed-forward neural networks of varying widths
+and depths. For each property, we set up model ensembles of multiple trained
+models and show that, on average, our proposed informed model performs better
+in extrapolating the three properties of previously unseen sodium borate glass
+samples than all five conventional blind models.",2308.09492v3
+2023-08-20,MgH2 nanoparticles confined in reduced graphene oxide pillared with organosilica: a novel type of hydrogen storage material,"Hydrogen is a promising energy carrier that can push forward the energy
+transition because of its high energy density (142 MJ kg-1), variety of
+potential sources, low weight and low environmental impact, but its storage for
+automotive applications remains a formidable challenge. MgH2, with its high
+gravimetric and volumetric density, presents a compelling platform for hydrogen
+storage; however, its utilization is hindered by the sluggish kinetics of
+hydrogen uptake/release and high temperature operation. Herein we show that a
+novel layered heterostructure of reduced graphene oxide and organosilica with
+high specific surface area and narrow pore size distribution can serve as a
+scaffold to host MgH2 nanoparticles with a narrow diameter distribution around
+~2.5 nm and superior hydrogen storage properties to bulk MgH2. Desorption
+studies showed that hydrogen release starts at 50 {\deg}C, with a maximum at
+348 {\deg}C and kinetics dependent on particle size. Reversibility tests
+demonstrated that the dehydrogenation kinetics and re-hydrogenation capacity of
+the system remains stable at 1.62 wt.% over four cycles at 200 {\deg}C. Our
+results prove that MgH2 confinement in a nanoporous scaffold is an efficient
+way to constrain the size of the hydride particles, avoid aggregation and
+improve kinetics for hydrogen release and recharging.",2308.10137v1
+2023-08-22,Direct assessment of the proton affinity of individual surface hydroxyls with non-contact atomic force microscopy,"The state of protonation/deprotonation of surfaces has far-ranging
+implications in all areas of chemistry: from acid-base catalysis$^1$ and the
+electro- and photocatalytic splitting of water$^2$, to the behavior of
+minerals$^3$ and biochemistry$^4$. The acidity of a molecule or a surface site
+is described by its proton affinity (PA) and pK$_\mathrm{a}$ value (the
+negative logarithm of the equilibrium constant of the proton transfer reaction
+in solution). For solids, in contrast to molecules, the acidity of individual
+sites is difficult to assess. For mineral surfaces such as oxides they are
+estimated by semi-empirical concepts such as bond-order valence sums$^5$, and
+also increasingly modeled with first-principles molecular dynamics
+simulations$^{6,7}$. Currently such predictions cannot be tested - the
+experimental measures used for comparison are typically average quantities
+integrated over the whole surface or, in some cases, individual crystal
+facets$^8$, such as the point of zero charge (pzc)$^9$. Here we assess
+individual hydroxyls on In$_2$O$_3$(111), a model oxide with four different
+types of surface oxygen atoms, and probe the strength of their hydrogen bond
+with the tip of a non-contact atomic force microscope (AFM). The force curves
+are in quantitative agreement with density-functional theory (DFT)
+calculations. By relating the results to known proton affinities and
+pK$_\mathrm{a}$ values of gas-phase molecules, we provide a direct measure of
+proton affinity distributions at the atomic scale.",2308.11437v1
+2023-08-25,Interacting Two-Level Systems as a Source of 1/f Charge Noise in Quantum Dot Qubits,"Charge noise in semiconducting quantum dots has been observed to have a 1/f
+spectrum. We propose a model in which a pair of quantum dots are coupled to a
+2D bath of fluctuating two level systems (TLS) that have electric dipole
+moments and that interact with each other, i.e., with the other fluctuators.
+These interactions are primarily via the elastic strain field. We use a 2D
+nearest-neighbor Ising spin glass to represent these elastic interactions and
+to simulate the dynamics of the bath of electric dipole fluctuators in the
+presence of a ground plane representing metal gates above the oxide layer
+containing the fluctuators. The interactions between the TLS cause the energy
+splitting of individual fluctuators to change with time. We calculate the
+resulting fluctuations in the electric potential at the two quantum dots that
+lie below the oxide layer. We find that 1/f electric potential noise spectra at
+the quantum dots and cross correlation in the noise between the two quantum
+dots are in qualitative agreement with experiment. Our simulations find that
+the cross correlations decrease exponentially with increasing quantum dot
+separation.",2308.13674v2
+2023-08-28,Crystal-Chemical Origins of the Ultrahigh Conductivity of Metallic Delafossites,"Despite their highly anisotropic complex-oxidic nature, certain delafossite
+compounds (e.g., PdCoO2, PtCoO2) are the most conductive oxides known, for
+reasons that remain poorly understood. Their room-temperature conductivity can
+exceed that of Au, while their low-temperature electronic mean-free-paths reach
+an astonishing 20 microns. It is widely accepted that these materials must be
+ultrapure to achieve this, although the methods for their growth (which produce
+only small crystals) are not typically capable of such. Here, we first report a
+new approach to PdCoO2 crystal growth, using chemical vapor transport methods
+to achieve order-of-magnitude gains in size, the highest structural qualities
+yet reported, and record residual resistivity ratios (>440). Nevertheless, the
+first detailed mass spectrometry measurements on these materials reveal that
+they are not ultrapure, typically harboring 100s-of-parts-per-million impurity
+levels. Through quantitative crystal-chemical analyses, we resolve this
+apparent dichotomy, showing that the vast majority of impurities are forced to
+reside in the Co-O octahedral layers, leaving the conductive Pd sheets highly
+pure (~1 ppm impurity concentrations). These purities are shown to be in
+quantitative agreement with measured residual resistivities. We thus conclude
+that a previously unconsidered ""sublattice purification"" mechanism is essential
+to the ultrahigh low-temperature conductivity and mean-free-path of metallic
+delafossites.",2308.14257v2
+2023-08-29,In-situ Plasma Studies using a Direct Current Microplasma in a Scanning Electron Microscope,"Microplasmas can be used for a wide range of technological applications and
+to improve our understanding of fundamental physics. Scanning electron
+microscopy, on the other hand, provides insights into the sample morphology and
+chemistry of materials from the mm-down to the nm-scale. Combining both would
+provide direct insight into plasma-sample interactions in real-time and at high
+spatial resolution. Up till now, very few attempts in this direction have been
+made, and significant challenges remain. This work presents a stable direct
+current glow discharge microplasma setup built inside a scanning electron
+microscope. The experimental setup is capable of real-time in-situ imaging of
+the sample evolution during plasma operation and it demonstrates localized
+sputtering and sample oxidation. Further, the experimental parameters such as
+varying gas mixtures, electrode polarity, and field strength are explored and
+experimental $V$-$I$ curves under various conditions are provided. These
+results demonstrate the capabilities of this setup in potential investigations
+of plasma physics, plasma-surface interactions, and materials science and its
+practical applications. The presented setup shows the potential to have several
+technological applications, e.g., to locally modify the sample surface (e.g.,
+local oxidation and ion implantation for nanotechnology applications) on the
+$\mu$m-scale.",2308.15123v1
+2023-09-05,Optical absorption spectra of metal oxides from time-dependent density functional theory and many-body perturbation theory based on optimally-tuned hybrid functionals,"Using both time-dependent density functional theory (TDDFT) and the
+``single-shot"" $GW$ plus Bethe-Salpeter equation ($GW$-BSE) approach, we
+compute optical band gaps and optical absorption spectra from first principles
+for eight common binary and ternary closed-shell metal oxides (MgO,
+Al$_2$O$_3$, CaO, TiO$_2$, Cu$_2$O, ZnO, BaSnO$_3$, and BiVO$_4$), based on the
+non-empirical Wannier-localized optimally-tuned screened range-separated hybrid
+functional. Overall, we find excellent agreement between our TDDFT and $GW$-BSE
+results and experiment, with a mean absolute error less than 0.4 eV, including
+for Cu$_2$O and ZnO, traditionally considered to be challenging for both
+methods.",2309.02117v1
+2023-08-29,Infrared Nanoimaging of Hydrogenated Perovskite Nickelate Synaptic Devices,"Solid-state devices made from correlated oxides such as perovskite nickelates
+are promising for neuromorphic computing by mimicking biological synaptic
+function. However, comprehending dopant action at the nanoscale poses a
+formidable challenge to understanding the elementary mechanisms involved. Here,
+we perform operando infrared nanoimaging of hydrogen-doped correlated
+perovskite, neodymium nickel oxide (H-NdNiO3) devices and reveal how an applied
+field perturbs dopant distribution at the nanoscale. This perturbation leads to
+stripe phases of varying conductivity perpendicular to the applied field, which
+define the macroscale electrical characteristics of the devices. Hyperspectral
+nano-FTIR imaging in conjunction with density functional theory calculations
+unveil a real-space map of multiple vibrational states of H-NNO associated with
+OH stretching modes and their dependence on the dopant concentration. Moreover,
+the localization of excess charges induces an out-of-plane lattice expansion in
+NNO which was confirmed by in-situ - x-ray diffraction and creates a strain
+that acts as a barrier against further diffusion. Our results and the
+techniques presented here hold great potential to the rapidly growing field of
+memristors and neuromorphic devices wherein nanoscale ion motion is
+fundamentally responsible for function.",2309.04486v1
+2023-09-23,LES of a non-premixed hydrogen flame stabilized by bluff-bodies of various shapes,"Dynamics of flames stabilized downstream of different shape bluff-bodies
+(cylindrical, square, star) with different wall topologies (flat, wavy) is
+investigated using large-eddy simulations (LES). A two-stage computational
+procedure involving the ANSYS software and an in-house academic high-order code
+is combined to model a flow in the vicinity of the bluff-bodies and a flame
+formed downstream. The fuel is nitrogen-diluted hydrogen and the oxidizer is
+hot air in which the fuel auto-ignites. After the ignition, the flame
+propagates towards the bluff-body surfaces and stabilizes in their vicinity. It
+is shown that the flames reflect the bluff-body shape due to large-scale strong
+vortices induced in the shear layer formed between the main recirculation zone
+and the oxidizer stream. The influence of the acute corners of the bluff-bodies
+on the flame dynamics is quantified by analysing instantaneous and
+time-averaged results. Compared to the classical conical bluff-body the largest
+differences in the temperature and velocity distributions are observed in the
+configuration with the square bluff-body. The main recirculation zone is
+shortened by approximately 15% and at its end temperature in the axis of the
+flame is almost 200 K larger. Simultaneously, their fluctuations are slightly
+larger than in the remaining cases. The influence of the wall topology (flat
+vs. wavy) in the configuration with the classical conical bluff-body turned out
+to be very small and it resulted in modifications of the flow and flame
+structures only in the direct vicinity of the bluff-body surface.",2309.13344v1
+2023-09-26,Fast emitting nanocomposites for high-resolution ToF-PET imaging based on multicomponent scintillators,"Time-of-Flight Positron Emission Tomography is a medical imaging technique,
+based on the detection of two back-to-back {\gamma}-photons generated from
+radiotracers injected in the body. Its limit is the ability of employed
+scintillation detectors to discriminate in time the arrival of {\gamma}-pairs,
+i.e. the coincidence time resolution (CTR). A CTR < 50 ps that would enable
+fast imaging with ultralow radiotracer dose. Monolithic materials do not have
+simultaneously the required high light output and fast emission
+characteristics, thus the concept of scintillating heterostructure is proposed,
+where the device is made of a dense scintillator coupled to a fast-emitting
+light material. Here we present a composite polymeric scintillator, whose
+density has been increased upon addition of hafnium oxide nanoparticles. This
+enhanced by +300% its scintillation yield, surpassing commercial plastic
+scintillators. The nanocomposite is coupled to bismuth germanate oxide (BGO)
+realizing a multilayer scintillator. We observed the energy sharing between its
+components, which activate the nanocomposite fast emission enabling a net CTR
+improvement of 25% with respect to monolithic BGO. These results demonstrate
+that a controlled loading with dense nanomaterials is an excellent strategy to
+enhance the performance of polymeric scintillators for their use in advanced
+radiation detection and imaging technologies.",2309.14968v1
+2023-09-26,SuperGaN: Synthesis of NbTiN/GaN/NbTiN Tunnel Junctions,"Nb-based circuits have broad applications in quantum-limited photon
+detectors, low-noise parametric amplifiers, superconducting digital logic
+circuits, and low-loss circuits for quantum computing. The current
+state-of-the-art approach for superconductor-insulator-superconductor (SIS)
+junction material is the Gurvitch trilayer process based on magnetron
+sputtering of Nb electrodes with Al-Oxide or AlN tunnel barriers grown on an Al
+overlayer. However, a current limitation of elemental Nb-based circuits is the
+low-loss operation of THz circuits operating above the 670 GHz gap frequency of
+Nb and operation at higher temperatures for projects with a strict power
+budget, such as space-based applications.
+  NbTiN is an alternative higher energy gap material and we have previously
+reported on the first NbTiN/AlN/NbTiN
+superconducting-insulating-superconducting (SIS) junctions with an epitaxially
+grown AlN tunnel barrier. One drawback of a directly grown tunnel barrier
+compared to thermal oxidation or plasma nitridation is control of the barrier
+thickness and uniformity across a substrate, leading to variations in current
+density (Jc). Semiconductor barriers with smaller barrier heights enable
+thicker tunnel barriers for a given Jc. GaN is an alternative semiconductor
+material with a closed-packed Wurtzite crystal structure similar to AlN and it
+can be epitaxially grown as a tunnel barrier using the Reactive Bias Target Ion
+Beam Deposition (RBTIBD) technique. This work presents the preliminary results
+of the first reported high-quality NbTiN/GaN/NbTiN heterojunctions with
+underdamped SIS I(V) characteristics.",2309.15100v1
+2023-10-02,Breaking Through the Plasma Wavelength Barrier to Extend the Transparency Range of Ultrathin Indium Tin Oxide Films into the Far Infrared,"Indium tin oxide (ITO) film, which is the most commonly used transparent
+conductive film (TCF), has traditionally been believed to be transparent in the
+visible spectrum but to reflect infrared (IR) light beyond the plasma
+wavelength (${\lambda}_p$). However, our theoretical analysis challenges this
+notion by demonstrating that an ultrathin ITO TCF that is thinner than the
+light's penetration depth, can overcome the transmission barrier at
+${\lambda}_p$. To validate the theoretical modeling, we have successfully
+fabricated ITO films that, despite having ${\lambda}_p \approx$ 1 ${\mu}$m,
+remain transparent from 400 nm to 20 ${\mu}$m. This represents the broadest
+transparency range ever reported for any In$_2$O$_3$-based TCF. The 10-nm-thick
+ITO TCFs have high visible transmittance (91.0% at 550 nm), low resistivity (5
+$\times$ 10$^{-4}$ ${\Omega}\cdot$ cm), and good IR transmittance (averaging
+60% over 1.35 $\unicode{x2013}$ 18.35 ${\mu}$m). Their IR transparency
+facilitates radiative cooling of the underlying circuitry. When an operational
+resistor is enclosed by commercial ITO TCFs that are 140 nm thick, its
+temperature increases. However, using 10-nm-thick ITO TCFs instead of the
+commercial ones can completely avoid this temperature rise. Moreover, attaching
+a silver grid to a 10-nm-thick ITO TCF can reduce the effective sheet
+resistance to ~10 ${\Omega}/\square$ at the expense of only ~3% transmittance.
+This development paves the way for large-scale applications that require low
+sheet resistance and far-IR transparency.",2310.00984v1
+2023-10-02,"A review and outlook on anionic and cationic redox in Ni-, Li- and Mn-rich layered oxides LiMeO2 (Me = Li, Ni, Co, Mn)","The present work reviews the charge compensation in Ni based layered oxides
+(LiNi1-xMexO2 with x <= 0.2, Me = Co, Mn, space group R-3m) relating
+performance parameters to changes in the electronic and crystallographic
+structure of the cathode materials. Upon charge and discharge two fundamentally
+different redox mechanisms are observed: At low and medium states of charge
+(SOCs) charge compensation takes mainly place at oxygen sites while electron
+density is shifted from the oxygen lattice to nickel (formation of sigma
+bonds). At high SOCs the shift of electron density from the transition metals
+to oxygen (formation of pi bonds) enables an additional redox process but also
+oxygen release from the transition metal host structure and subsequent
+detrimental reactions. Depending on the Ni:Co:Mn content, both processes lead
+to characteristic features in the voltage profile of the cathode materials and
+performance parameters like the capacity, the cycling stability and the open
+cell voltage become a function of the composition.",2310.01295v2
+2023-10-03,Simulation Guided Molecular Design of Hydrofluoroether Solvent for High Energy Batteries,"Electrolyte design is critical for enabling next-generation batteries with
+higher energy densities. Hydrofluoroether (HFE) solvents have drawn a lot of
+attention as the electrolytes based on HFEs showed great promise to deliver
+highly desired properties, including high oxidative stability, ionic
+conductivity, as well as enhanced lithium metal compatibility. However, the
+structure-dynamics-properties relationships and design principles for
+high-performance HFE solvents are still poorly understood. Herein, we proposed
+four novel asymmetric HFE designs by systematically varying polyether and
+fluorocarbon structural building blocks. By leveraging molecular dynamics (MD)
+modeling to analyze the solvation structures and predict the properties of the
+corresponding 1 M lithium bis(fluorosulfonyl)imide (LiTFSI) solutions, we
+downselected the most promising candidate based on high conductivity, solvation
+species distribution, and oxidative stability for extensive electrochemical
+characterizations. The formulated electrolyte demonstrated properties
+consistent with the predictions from the simulations and showed much-improved
+capacity retention as well as Coulombic efficiency compared to the baseline
+electrolytes when cycled in lithium metal cells. This work exemplifies the
+construction of candidate electrolytes from building block functional moieties
+to engineer fundamental solvation structures for desired electrolyte properties
+and guide the discovery and rational design of new solvent materials.",2310.02188v1
+2023-10-10,Mitigation of interfacial dielectric loss in aluminum-on-silicon superconducting qubits,"We demonstrate aluminum-on-silicon planar transmon qubits with time-averaged
+${T_1}$ energy relaxation times of up to ${270\,\mu s}$, corresponding to Q = 5
+million, and a highest observed value of ${501\,\mu s}$. We use materials
+analysis techniques and numerical simulations to investigate the dominant
+sources of energy loss, and devise and demonstrate a strategy towards
+mitigating them. The mitigation of loss is achieved by reducing the presence of
+oxide, a known host of defects, near the substrate-metal interface, by growing
+aluminum films thicker than 300 nm. A loss analysis of coplanar-waveguide
+resonators shows that the improvement is owing to a reduction of dielectric
+loss due to two-level system defects. We perform time-of-flight secondary ion
+mass spectrometry and observe a reduced presence of oxygen at the
+substrate-metal interface for the thicker films. The correlation between the
+enhanced performance and the film thickness is due to the tendency of aluminum
+to grow in columnar structures of parallel grain boundaries, where the size of
+the grain depends on the film thickness: transmission electron microscopy
+imaging shows that the thicker film has larger grains and consequently fewer
+grain boundaries containing oxide near this interface. These conclusions are
+supported by numerical simulations of the different loss contributions in the
+device.",2310.06797v1
+2023-10-25,Proton and molecular permeation through the basal plane of monolayer graphene oxide,"Two-dimensional (2D) materials offer a prospect of membranes that combine
+negligible gas permeability with high proton conductivity and could outperform
+the existing proton exchange membranes used in various applications including
+fuel cells. Graphene oxide (GO), a well-known 2D material, facilitates rapid
+proton transport along its basal plane but proton conductivity across it
+remains unknown. It is also often presumed that individual GO monolayers
+contain a large density of nanoscale pinholes that lead to considerable gas
+leakage across the GO basal plane. Here we show that relatively large,
+micrometer-scale areas of monolayer GO are impermeable to gases, including
+helium, while exhibiting proton conductivity through the basal plane which is
+nearly two orders of magnitude higher than that of graphene. These findings
+provide insights into the key properties of GO and demonstrate that chemical
+functionalization of 2D crystals can be utilized to enhance their proton
+transparency without compromising gas impermeability.",2310.16495v1
+2023-10-30,Interfacial Tension Hysteresis of Eutectic Gallium-Indium,"When in a pristine state, gallium and its alloys have the largest interfacial
+tensions of any liquid at room temperature. Nonetheless, applying as little as
+0.8 V of electric potential across eutectic gallium indium (EGaIn) placed
+within aqueous NaOH (or other electrolyte) solution will cause the metal to
+behave as if its interfacial tension is near zero. The mechanism behind this
+phenomenon has remained poorly understood because NaOH dissolves the oxide
+species, making it difficult to directly measure the concentration, thickness,
+or chemical composition of the film that forms at the interface. In addition,
+the oxide layers formed are atomically-thin. Here, we present a suite of
+techniques which allow us to simultaneously measure both electrical and
+interfacial properties as a function of applied electric potential, allowing
+for new insights into the mechanisms which cause the dramatic decrease in
+interfacial tension. A key discovery from this work is that the interfacial
+tension displays hysteresis while lowering the applied potential. We combine
+these observations with electrochemical impedance spectroscopy to evaluate how
+these changes in interfacial tension arise from chemical, electrical, and
+mechanical changes on the interface, and close with ideas for how to build a
+free energy model to predict these changes from first principles.",2310.19298v1
+2023-11-03,Generalization of Graph-Based Active Learning Relaxation Strategies Across Materials,"Although density functional theory (DFT) has aided in accelerating the
+discovery of new materials, such calculations are computationally expensive,
+especially for high-throughput efforts. This has prompted an explosion in
+exploration of machine learning assisted techniques to improve the
+computational efficiency of DFT. In this study, we present a comprehensive
+investigation of the broader application of Finetuna, an active learning
+framework to accelerate structural relaxation in DFT with prior information
+from Open Catalyst Project pretrained graph neural networks. We explore the
+challenges associated with out-of-domain systems: alcohol ($C_{>2}$) on metal
+surfaces as larger adsorbates, metal-oxides with spin polarization, and
+three-dimensional (3D) structures like zeolites and metal-organic-frameworks.
+By pre-training machine learning models on large datasets and fine-tuning the
+model along the simulation, we demonstrate the framework's ability to conduct
+relaxations with fewer DFT calculations. Depending on the similarity of the
+test systems to the training systems, a more conservative querying strategy is
+applied. Our best-performing Finetuna strategy reduces the number of DFT
+single-point calculations by 80% for alcohols and 3D structures, and 42% for
+oxide systems.",2311.01987v1
+2023-11-06,Sub-5-nm Ultra-thin In$_2$O$_3$ Transistors for High-Performance and Low-Power Electronic Applications,"Ultra-thin (UT) oxide semiconductors are promising candidates for
+back-end-of-line (BEOL) compatible transistors and monolithic three-dimensional
+integration. Experimentally, UT indium oxide (In$_2$O$_3$) field-effect
+transistors (FETs) with thicknesses down to 0.4 nm exhibits extremely high
+drain current (10000 $\mu$A/$\mu$m) and transconductance (4000 $\mu$S/$\mu$m).
+Here, we employ the ab initio quantum transport simulation to investigate the
+performance limit of sub-5-nm gate length (Lg) UT In$_2$O$_3$ FET. Based on the
+International Technology Roadmap for Semiconductors (ITRS) criteria for
+high-performance (HP) devices, the scaling limit of UT In$_2$O$_3$ FETs can
+reach 2 nm in terms of on-state current, delay time, and power dissipation. The
+wide bandgap nature of UT In$_2$O$_3$ (3.15 eV) renders it a suitable candidate
+for ITRS low-power (LP) electronics with Lg down to 3 nm. Both the HP and LP UT
+In$_2$O$_3$ FETs exhibit superior energy-delay products as compared to other
+common 2D semiconductors such as monolayer MoS2 and MoTe2. Our study unveils
+the immense promise of UT In$_2$O$_3$ for both HP and LP device applications.",2311.02943v1
+2023-11-08,"Interaction of monoclinic ZrO$_2$ grain boundaries with oxygen vacancies, Sn and Nb -- implications for the corrosion of Zr alloy fuel cladding","We used density-functional-theory simulations to examine the structural and
+electronic properties of the $\Sigma 180{\deg}(100)[001] $ grain boundary in
+monoclinic ZrO$_2$, which is a very low-energy (0.06Jm$^{-2}$) twin boundary
+present in experimental oxide texture maps, with suggested special properties.
+This equilibrium structure was compared with a metastable structure (with a
+boundary energy of 0.32Jm$^{-2}$), which was considered to be representative of
+a more general oxide boundary. The interaction of oxygen vacancies,
+substitutional Sn and Nb defects (substituting host Zr sites) with both
+structures - and their effect on the boundary properties - were examined. We
+found that the equilibrium structure energetically favours V$_\textrm{O}^{2+}$
+and Nb$_\textrm{Zr}^{2-}$, whereas the metastable structure favours
+V$_\textrm{O}^{2+}$ and Sn$_\textrm{Zr}^{2-}$. Tin was further found to bind
+strongly with oxygen vacancies in both structures, and introduce gap states in
+the band gap of their electronic structure. Sn$_\textrm{Zr}^{2-}$ was, however,
+found to increase the segregation preference of V$_\textrm{O}^{2+}$ for the
+metastable structure, which might contribute to increased oxygen and electron
+transport down this interface, and therefore other more general boundaries,
+compared to the equilibrium structure of the studied monoclinic twin boundary.",2311.04667v1
+2023-11-27,Initial Characterization of the First Speedster-EXD550 Event-Driven X-Ray Hybrid Complementary Metal-Oxide Semiconductor Detectors,"Future x-ray observatories will require imaging detectors with fast readout
+speeds that simultaneously achieve or exceed the other high performance
+parameters of x-ray charge-coupled devices (CCDs) used in many missions over
+the past three decades. Fast readout will reduce the impact of pile-up in
+missions with large collecting areas while also improving performance in other
+respects like timing resolution. Event-driven readout, in which only pixels
+with charge from x-ray events are read out, can be used to achieve these faster
+operating speeds. Speedster-EXD550 detectors are hybrid complementary
+metal-oxide semiconductor (CMOS) detectors capable of event-driven readout,
+developed by Teledyne Imaging Sensors and Penn State University. We present
+initial results from measurements of the first of these detectors,
+demonstrating their capabilities and performance in both full-frame and
+event-driven readout modes. These include dark current, read noise, gain
+variation, and energy resolution measurements from the first two
+engineering-grade devices.",2311.16270v2
+2023-11-30,Design Space and Variability Analysis of SOI MOSFET for Ultra-Low Power Band-to-Band Tunneling Neurons,"Large spiking neural networks (SNNs) require ultra-low power and low
+variability hardware for neuromorphic computing applications. Recently, a
+band-to-band tunneling-based (BTBT) integrator, enabling sub-kHz operation of
+neurons with area and energy efficiency, was proposed. For an ultra-low power
+implementation of such neurons, a very low BTBT current is needed, so
+minimizing current without degrading neuronal properties is essential. Low
+variability is needed in the ultra-low current integrator to avoid network
+performance degradation in a large BTBT neuron-based SNN. To address this, we
+conducted design space and variability analysis in TCAD, utilizing a
+well-calibrated TCAD deck with experimental data from GlobalFoundries 32nm
+PD-SOI MOSFET. First, we discuss the physics-based explanation of the tunneling
+mechanism. Second, we explore the impact of device design parameters on SOI
+MOSFET performance, highlighting parameter sensitivities to tunneling current.
+With device parameters' optimization, we demonstrate a ~20x reduction in BTBT
+current compared to the experimental data. Finally, a variability analysis that
+includes the effects of random dopant fluctuations (RDF), oxide thickness
+variability (OTV), and channel-oxide interface traps DIT in the BTBT, SS, and
+ON regimes of operation is shown. The BTBT regime shows high sensitivity to the
+RDF and OTV as any variation in them directly modulates the tunnel length or
+the electric field at the drain-channel junction, whereas minimal sensitivity
+to DIT is observed.",2311.18577v1
+2023-11-13,Thermal and electrostatic tuning of surface phonon-polaritons in LaAlO3/SrTiO3 heterostructures,"Phonon polaritons are promising for infrared applications due to a strong
+light-matter coupling and subwavelength energy confinement they offer. Yet, the
+spectral narrowness of the phonon bands and difficulty to tune the phonon
+polariton properties hinder further progress in this field. SrTiO3 - a
+prototype perovskite oxide - has recently attracted attention due to two
+prominent far-infrared phonon polaritons bands, albeit without any tuning
+reported so far. Here we show, using cryogenic infrared near-field microscopy,
+that long-propagating surface phonon polaritons are present both in bare SrTiO3
+and in LaAlO3/SrTiO3 heterostructures hosting a two-dimensional electron gas.
+The presence of the two-dimensional electron gas increases dramatically the
+thermal variation of the upper limit of the surface phonon polariton band due
+to temperature dependent polaronic screening of the surface charge carriers.
+Furthermore, we demonstrate a tunability of the upper surface phonon polariton
+frequency in LaAlO3/SrTiO3 via electrostatic gating. Our results suggest that
+oxide interfaces are a new platform bridging unconventional electronics and
+long-wavelength nanophotonics.",2312.03711v1
+2023-12-08,A novel control strategy to neutralize heat source within solid oxide electrolysis cell (SOEC) under variable solar power conditions,"The integration of a solid oxide electrolysis cell (SOEC) with a photovoltaic
+(PV) system presents a viable method for storing variable solar energy through
+the production of green hydrogen. To ensure the SOEC's safety and longevity
+amidst dramatic fluctuations in solar power, control strategies are needed to
+limit the temperature gradients and rates of temperature change within the
+SOEC. Recognizing that the reactant supply influences the current, a novel
+control strategy is developed to modulate heat generation in the SOEC by
+adjusting the fuel flow rate. The effectiveness of this strategy is assessed
+through numerical simulations conducted on a coupled PV-SOEC system using
+actual solar irradiance data, recorded at two-second intervals, to account for
+rapid changes in solar exposure. The results indicate that conventional control
+strategies, which increase airflow rates, are inadequate in effectively
+suppressing the rate of temperature variation in scenarios of drastic solar
+power changes. In contrast, our proposed strategy demonstrates successful
+management of the SOEC's heat generation, thereby reducing the temperature
+gradient and rate of variation within the SOEC to below 5 K/cm and 1 K/min,
+respectively.",2312.04923v3
+2024-01-10,Wafer-scale CMOS-compatible graphene Josephson field-effect transistors,"Electrostatically tunable Josephson field-effect transistors (JoFETs) are one
+of the most desired building blocks of quantum electronics. JoFET applications
+range from parametric amplifiers and superconducting qubits to a variety of
+integrated superconducting circuits. Here, we report on graphene JoFET devices
+fabricated with wafer-scale complementary metal-oxide-semiconductor (CMOS)
+compatible processing based on wet transfer of chemical vapour deposited
+graphene, atomic-layer-deposited Al$_{2}$O$_{3}$ gate oxide, and evaporated
+superconducting Ti/Al source, drain, and gate contacts. By optimizing the
+contact resistance down to $\sim$ 170 $\Omega \mu m$, we observe
+proximity-induced superconductivity in the JoFET channels with different gate
+lengths of 150 - 350 nm. The Josephson junction devices show reproducible
+critical current $I_{\text{C}}$ tunablity with the local top gate. Our JoFETs
+are in short diffusive limit with the $I_{\text{C}}$ reaching up to $\sim\,$3
+$\mu A$ for a 50 $\mu m$ channel width. Overall, our successful demonstration
+of CMOS-compatible 2D-material-based JoFET fabrication process is an important
+step toward graphene-based integrated quantum circuits.",2401.05089v2
+2024-01-14,Waveguide optical parametric amplifiers in silicon nitride with 2D graphene oxide films,"Optical parametric amplification (OPA) represents a powerful solution to
+achieve broadband amplification in wavelength ranges beyond the scope of
+conventional gain media, for generating high-power optical pulses, optical
+microcombs, entangled photon pairs and a wide range of other applications.
+Here, we demonstrate optical parametric amplifiers based on silicon nitride
+(Si3N4) waveguides integrated with two-dimensional (2D) layered graphene oxide
+(GO) films. We achieve precise control over the thickness, length, and position
+of the GO films using a transfer-free, layer-by-layer coating method combined
+with accurate window opening in the chip cladding using photolithography.
+Detailed OPA measurements with a pulsed pump for the fabricated devices with
+different GO film thicknesses and lengths show a maximum parametric gain of
+~24.0 dB, representing a ~12.2 dB improvement relative to the device without
+GO. We perform a theoretical analysis of the device performance, achieving good
+agreement with experiment and showing that there is substantial room for
+further improvement. This work represents the first demonstration of
+integrating 2D materials on chips to enhance the OPA performance, providing a
+new way of achieving high performance photonic integrated OPA by incorporating
+2D materials.",2401.07198v1
+2024-01-15,Crystallization Instead of Amorphization in Collision Cascades in Gallium Oxide,"Disordering of solids typically leads to amorphization, but polymorph
+transitions, facilitated by favorable atomic rearrangements, may temporarily
+help to maintain long-range periodicity in the solid state. In
+far-from-equilibrium situations, such as atomic collision cascades, these
+rearrangements may not necessarily follow a thermodynamically gainful path, but
+may be kinetically limited. In this Letter, we focused on such crystallization
+instead of amorphization in collision cascades in gallium oxide (\ce{Ga2O3}).
+We determined the disorder threshold for irreversible $\beta$-to-$\gamma$
+polymorph transition and explained why it results in elevating energy to that
+of the $\gamma$-polymorph, which exhibits the highest polymorph energy in the
+system below the amorphous state. Specifically, we demonstrate that upon
+reaching the disorder transition threshold, the \ce{Ga}-sublattice kinetically
+favors transitioning to the $\gamma$-like configuration, requiring
+significantly less migration for \ce{Ga} atoms to reach the lattice sites
+during post-cascade processes. As such, our data provide a consistent
+explanation of this remarkable phenomenon and can serve as a toolbox for
+predictive multi-polymorph fabrication.",2401.07675v3
+2024-01-18,Iodine and Bromine Radical Reactions in Atmospheric Mercury Oxidation,"We investigate the atmospheric oxidation of mercury Hg(0) by halogens,
+initiated by Br and I to yield Hg(I), and continued by I, Br, BrO, ClO, IO, NO2
+and HO2 to yield Hg(II) or Hg(0) using computational methods with focus on
+determining the impact of rising iodine levels. We calculate reaction
+enthalpies and Gibbs free energies using the Coupled Cluster singlets,
+doublets, and perturbative triplets method (CCSD(T)) with the ma-def2-TZVP
+basis set and effective core potential to account for relativistic effects.
+Additionally, we investigate the reaction kinetics using variational transition
+state theory based on geometric scans of bond dissociations at the
+CASPT2/ma-def2-TZVP level. We compare the results obtained from the CASPT2 and
+CCSD(T) methods to help define the uncertainty. Our results provide insights
+into the mechanisms of these reactions and their implications for mercury
+depletion events and for the atmosphere as a whole. The reaction HgBr + Br ->
+HgBr2 was found to be twice as fast as HgI + I -> HgI2, with reaction rate
+coefficients of 8.8x10^-13 and 4.2x10^-13 cm^3 molecule^-1 s^-1 respectively.
+The BrHg + BrO -> BrHgOBr reaction was about 7.2 times faster than the HgI + IO
+-> IHgOI reaction with their rates being 3.3x10^-14 and 4.6x10^-15 cm^3
+molecule^-1 s^-1 respectively. We investigate the HgXOY (X and Y=halogen)
+complexes. We find that rising iodine levels will lead to shortened mercury
+lifetime due to the impact of the HgI + I -> HgI2 reaction.",2401.10053v1
+2024-01-25,Atomic multiplet and charge-transfer screening effects in 1$s$ and 2$p$ core-level X-ray photoelectron spectra of early 3$d$ transition-metal oxides,"We present a comparative analysis of 1$s$ and 2$p$ core-level hard X-ray
+photoelectron spectroscopy (HAXPES) spectra in metallic VO$_2$ and CrO$_2$.
+Even though the V 1$s$ and 2$p$ spectra in VO$_2$ display similar line shapes
+except the absence or presence of a spin-orbit coupling splitting, the Cr 1$s$
+and 2$p$ spectra exhibit distinct main-line shapes. The experimental HAXPES
+spectra are analyzed by the Anderson impurity model based on the density
+functional theory + dynamical mean-field theory and a conventional MO$_6$
+cluster model. We elucidate the complex interplay between formation of the
+intra-atomic multiplet and charge transfer effect on the chemical bonding
+followed by the 1$s$ and 2$p$ core electron excitations. We demonstrate the
+advantage of the 1$s$ excitations to the routinely-employed 2$p$ excitations
+for distinguishing between metal-ligand and metal-metal charge transfer
+contributions in early 3$d$ transition-metal oxides.",2401.13951v2
+2024-01-25,A facile one-pot hydrothermal synthesis as an efficient method to modulate the potassium content of cryptomelane and its effects on the redox and catalytic properties,"Cryptomelane has been widely applied as catalyst in oxidation reactions due
+to its excellent redox properties and low cost. Here, a novel one-pot
+hydrothermal synthesis using a potassium permanganate aqueous solution as
+precursor and ethanol as reducing agent has successfully been developed to
+obtain cryptomelane nano-oxides. This synthetic route makes it possible to
+control the amount of potassium incorporated into the structure of the
+cryptomelane by selecting the appropriate synthesis temperature and ethanol
+initial concentration. Taking advantage of this approach, the effect of
+potassium concentration on the structural stability and reducibility of the
+cryptomelane, which are poorly discussed in the literature, has been studied.
+We have observed that samples with low content of potassium (~11%) show high
+conversions of CO to CO2 especially at low temperatures. The lower activity of
+the samples with high K contents (~16%) can be ascribed to the beneficial
+effect of K on the structural stability of cryptomelane in detriment of labile
+oxygen on cryptomelane surface.",2401.14144v1
+2024-02-05,Scanning tunnelling microscopy and X-ray photoemission studies of NdNiO2 infinite-layer nickelates films,"We report scanning tunnelling microscopy (STM) and x-ray photoemission
+spectroscopy (XPS) measurements on uncapped and SrTiO3 (STO) capped NdNiO2
+realized by pulsed-laser deposition and topotactic reduction process. We find
+that untreated NdNiO2 surfaces are insulating and contain Ni mostly in a
+nominal Ni2+ oxidation state. Room temperature STM shows signatures of a
+striped-like topographic pattern, possibly compatible with recent reports of
+ordered oxygen vacancies in uncapped nickelates due to incomplete oxygen
+de-intercalation of the upper layers. A metallic surface and a full Ni1+
+oxidation state is recovered by ultra high vacuum annealing at 250 C, as shown
+by STM and XPS. STO-capped NdNiO2 films, on the other hand, show Ni mostly in
+Ni1+ configuration, but Nd 3d5/2 core level spectra have a relevant
+contribution from ligand 4f 4L states, suggesting the formation of a NdTiNiOx
+layer at the interface with the STO. By in situ unit-cell by unit-cell Ar-ion
+sputtering removal of the STO capping and of the non stoichiometric interface
+layer, we were able to address the surface electronic properties of these
+samples, as shown by high resolution valence band photoemission spectroscopy.
+The results provide insights in the properties of infinite-layer NdNiO2 thin
+films prepared by the CaH2 topotactic reduction of perovskite NdNiO3 and
+suggest methods to improve their surface quality.",2402.03143v1
+2024-02-06,Reducing two-level system dissipations in 3D superconducting Niobium resonators by atomic layer deposition and high temperature heat treatment,"Superconducting qubits have arisen as a leading technology platform for
+quantum computing which is on the verge of revolutionizing the world's
+calculation capacities. Nonetheless, the fabrication of computationally
+reliable qubit circuits requires increasing the quantum coherence lifetimes,
+which are predominantly limited by the dissipations of two-level system (TLS)
+defects present in the thin superconducting film and the adjacent dielectric
+regions. In this paper, we demonstrate the reduction of two-level system losses
+in three-dimensional superconducting radio frequency (SRF) niobium resonators
+by atomic layer deposition (ALD) of a 10 nm aluminum oxide Al2O3 thin films
+followed by a high vacuum (HV) heat treatment at 650 {\deg}C for few hours. By
+probing the effect of several heat treatments on Al2O3-coated niobium samples
+by X-ray photoelectron spectroscopy (XPS) plus scanning and conventional high
+resolution transmission electron microscopy (STEM/HRTEM) coupled with electron
+energy loss spectroscopy (EELS) and (EDX) , we witness a dissolution of niobium
+native oxides and the modification of the Al2O3-Nb interface, which correlates
+with the enhancement of the quality factor at low fields of two 1.3 GHz niobium
+cavities coated with 10 nm of Al2O3.",2402.04137v1
+2024-02-07,Large Eddy Simulation of the evolution of the soot size distribution in turbulent nonpremixed bluff body flames,"Large Eddy Simulation (LES) was used to investigate the evolution of the soot
+size distribution in a series of turbulent nonpremixed bluff body flames, with
+different bluff body diameters. The new Bivariate Multi-Moment Sectional Method
+(BMMSM) is employed to characterize the size distribution. BMMSM combines
+elements of sectional methods and methods of moments and is capable of
+reproducing fractal aggregate morphology, thanks to its joint volume-surface
+formulation, all at relatively low computational costs with fewer transported
+soot scalars compared to traditional sectional methods. LES results show soot
+volume fraction profiles agreeing correctly with the experimental measurements,
+exhibiting significant improvement compared to previous work using the HMOM.
+The evolution of the particle size distribution function (PSDF) was examined
+across the flame series and show that the size distribution is less sensitive
+to the bluff body diameter than the overall soot volume fraction, which
+increases with increasing bluff body diameter. The PSDF across the flame
+exhibit different features compared to turbulent nonpremixed jet flames. The
+long residence times in the recirculation zone leads to a nearly bimodal size
+distribution, which eventually becomes bimodal in the downstream jet-like
+region. Further analysis indicates that a size distribution model is needed to
+correctly predict the soot evolution. Remarkably, due to improved descriptions
+of oxidation with BMMSM compared to HMOM, significant nucleation and
+condensation rates in both the recirculation zone and jet-like region were
+found using BMMSM, on the same order of magnitude as surface growth and
+oxidation, leading to the improved prediction of mean soot volume fraction
+compared to HMOM. This work reveals that the need of size distribution is
+crucial to both predict global soot quantities accurately and reproduce
+fundamental mechanisms.",2402.04560v1
+2024-02-07,Millimeter-scale freestanding superconducting infinite-layer nickelate membranes,"Progress in the study of infinite-layer nickelates has always been highly
+linked to materials advances. In particular, the recent development of
+superconductivity via hole-doping was predicated on the controlled synthesis of
+Ni in a very high oxidation state, and subsequent topotactic reduction to a
+very low oxidation state, currently limited to epitaxial thin films. Here we
+demonstrate a process to combine these steps with a heterostructure which
+includes an epitaxial soluble buffer layer, enabling the release of
+freestanding membranes of (Nd,Sr)NiO2 encapsulated in SrTiO3, which serves as a
+protective layer. The membranes have comparable structural and electronic
+properties to that of optimized thin films, and range in lateral dimensions
+from millimeters to ~100 micron fragments, depending on the degree of strain
+released with respect to the initial substrate. The changes in the
+superconducting transition temperature associated with membrane release are
+quite similar to those reported for substrate and pressure variations,
+suggestive of a common underlying mechanism. These membranes structures should
+provide a versatile platform for a range of experimental studies and devices
+free from substrate constraints.",2402.05104v1
+2024-02-08,"Photo-Activated, Solid-State Introduction of Luminescent Oxygen Defects into Semiconducting Single-Walled Carbon Nanotubes","Oxygen defects in semiconducting single-walled carbon nanotubes (SWCNTs) are
+localized disruptions in the carbon lattice caused by the formation of epoxy or
+ether groups, commonly through wet-chemical reactions. The associated
+modifications of the electronic structure can result in luminescent states with
+emission energies below those of pristine SWCNTs in the near-infrared range,
+which makes them promising candidates for applications in biosensing and as
+single-photon emitters. Here, we demonstrate the controlled introduction of
+luminescent oxygen defects into networks of monochiral (6,5) SWCNTs using a
+solid-state photocatalytic approach. UV irradiation of SWCNTs on the
+photoreactive surfaces of the transition metal oxides TiOx and ZnOx in the
+presence of trace amounts of water and oxygen results in the creation of
+reactive oxygen species that initiate radical reactions with the carbon lattice
+and the formation of oxygen defects. The created ether-d and epoxide-l defect
+configurations give rise to two distinct red-shifted emissive features. The
+chemical and dielectric properties of the photoactive oxides influence the
+final defect emission properties, with oxygen-functionalized SWCNTs on TiOx
+substrates being brighter than those on ZnOx or pristine SWCNTs on glass. The
+photoinduced functionalization of nanotubes is further employed to create
+lateral patterns of oxygen defects in (6,5) SWCNT networks with micrometer
+resolution and thus spatially controlled defect emission.",2402.05572v1
+2024-02-12,Graphene Oxide and Polymer Humidity Micro-Sensors Prepared by Carbon Beam Writing,"In this study, novel flexible micro-scale humidity sensors were directly
+fabricated in graphene oxide (GO) and polyimide (PI) using ion beam writing
+without any further modifications, and then successfully tested in an
+atmospheric chamber. Two low fluences of carbon ions with an energy of 5 MeV
+were used, and structural changes in the irradiated materials were expected.
+The shape and structure of prepared micro-sensors were studied using scanning
+electron microscopy (SEM). The structural and compositional changes in the
+irradiated area were characterized using micro-Raman spectroscopy, X-ray
+photoelectron spectroscopy (XPS), Rutherford back-scattering spectroscopy
+(RBS), energy-dispersive X-ray spectroscopy (EDS), and elastic recoil detection
+analysis (ERDA) spectroscopy. The sensing performance was tested at a relative
+humidity (RH) ranging from 5 % to 60 %, where the electrical conductivity of PI
+varied by three orders of magnitude, and the electrical capacitance of GO
+varied in the order of pico-farads. In addition, the PI sensor has proven
+long-term sensing stability in air. We demonstrated a novel method of ion
+micro-beam writing to prepare flexible micro-sensors that function over a wide
+range of humidity and have good sensitivity and great potential for widespread
+applications.",2402.07651v1
+2024-02-20,Are boron-nitride nanobelts capable to capture greenhouse gases?,"Why is the question in the title pertinent? Toxic gases, which are
+detrimental to both human health and the environment, have been released in
+greater quantities as a result of industrial development. These gases
+necessitate capture, immobilization, and measurement. Consequently, the present
+study investigates the interactions between boron-nitride nanobelt and
+M\""obius-type boron-nitride nanobelt and nine greenhouse gases, namely ammonia,
+carbon dioxide, carbon monoxide, hydrogen sulfide, methane, methanol, nitric
+dioxide, nitric oxide, and phosgene. The adsorption energies calculated for the
+structures with optimized geometry are all negative, suggesting that all gases
+are adsorbed favorably in both nanobelts. Furthermore, we discovered that the
+recovery time of the sensors ranges from two hours to a few nanoseconds, and
+that the nanobelts exhibit distinct responses to each gas. According to
+electronic and topological investigations, covalent bonds were exclusively
+formed by nitric oxide; the remaining gases formed non-covalent bonds.
+Molecular dynamics ultimately demonstrate that the interaction between a single
+gas molecule and the nanobelt remains consistent across the vast majority of
+gases, whereas the interaction between 500 gas molecules and the nanobelts
+functions as an attraction, notwithstanding the impact of volumetric effects
+characteristic of high volume gases on the interaction. For the completion of
+each calculation, semiempirical tight-binding methods were implemented
+utilizing the xTB software. The outcomes of our study generated a favorable
+response to the inquiry posed in the title.",2402.13102v1
+2024-02-23,Effect of temperature and copper doping on the heterogeneous Fenton-like activity of Cu$_x$Fe$_{3-x}$O$_4$ nanoparticles,"Ferrite nanoparticles serve as potent heterogeneous Fenton-like catalysts,
+producing reactive oxygen species (ROS) for decomposing organic pollutants. We
+investigated the impact of temperature and copper content on the catalytic
+activity of nanoparticles with different oxidation states of iron. Via
+solvothermal synthesis, we fabricated copper-doped magnetite
+(Cu$_x$Fe$_{3-x}$O$_4$) with a Fe$^{2+}$/Fe ratio ~0.33 for the undoped system.
+Using a microwave-assisted method, we produced copper-doped oxidized ferrites,
+yielding a Fe$^{2+}$/Fe ratio of ~0.11 for the undoped nanoparticles. The ROS
+generated by the catalyst were identified and quantified by electron
+paramagnetic resonance, while optical spectroscopy allowed us to evaluate its
+effectiveness for the degradation of a model organic dye. At room temperature,
+the magnetite nanoparticles exhibited the most $\cdot$OH radical production and
+achieved almost 90% dye discoloration in 2 hours. This efficiency decreased
+with increasing Cu concentration, concurrently with a decrease in $\cdot$OH
+generation. Conversely, above room temperature, Cu-doped nanoparticles
+significantly enhance the dye degradation, reaching 100% discoloration at
+90$^\circ$C. This enhancement is accompanied by a systematic increase in the
+kinetic constants, obtained from reaction equations, with Cu doping. This study
+highlights the superior stability and high-temperature catalytic advantages of
+copper ferrite holding promise for enhancing the performance of nanocatalysts
+for decomposing organic contaminants.",2402.15338v1
+2024-02-23,Two-dimensional photonic crystal cavities in ZnSe quantum well structures,"ZnSe and related materials like ZnMgSe and ZnCdSe are promising II-VI host
+materials for optically mediated quantum information technology such as single
+photon sources or spin qubits. Integrating these heterostructures into photonic
+crystal (PC) cavities enables further improvements, for example realizing
+Purcell-enhanced single photon sources with increased quantum efficiency. Here
+we report on the successful implementation of two-dimensional (2D) PC cavities
+in strained ZnSe quantum wells (QW) on top of a novel AlAs supporting layer.
+This approach overcomes typical obstacles associated with PC membrane
+fabrication in strained materials, such as cracks and strain relaxation in the
+corresponding devices. We demonstrate the attainment of the required mechanical
+stability in our PC devices, complete strain retainment and effective vertical
+optical confinement. Structural analysis of our PC cavities reveals excellent
+etching anisotropy. Additionally, elemental mapping in a scanning transmission
+electron microscope confirms the transformation of AlAs into AlOx by
+post-growth wet oxidation and reveals partial oxidation of ZnMgSe at the etched
+sidewalls in the PC. This knowledge is utilized to tailor FDTD simulations and
+to extract the ZnMgSe dispersion relation with small oxygen content. Optical
+characterization of the PC cavities with cross-polarized resonance scattering
+spectroscopy verifies the presence of cavity modes. The excellent agreement
+between simulation and measured cavity mode energies demonstrates wide
+tunability of the PC cavity and proves the pertinence of our model. This
+implementation of 2D PC cavities in the ZnSe material system establishes a
+solid foundation for future developments of ZnSe quantum devices.",2402.15349v1
+2024-03-01,"Characterization of process-related interfacial dielectric loss in aluminum-on-silicon by resonator microwave measurements, materials analysis, and imaging","We systematically investigate the influence of the fabrication process on
+dielectric loss in aluminum-on-silicon superconducting coplanar waveguide
+resonators with internal quality factors ($Q_i$) of about one million at the
+single-photon level. These devices are essential components in superconducting
+quantum processors; they also serve as proxies for understanding the energy
+loss of superconducting qubits. By systematically varying several fabrication
+steps, we identify the relative importance of reducing loss at the
+substrate-metal and the substrate-air interfaces. We find that it is essential
+to clean the silicon substrate in hydrogen fluoride (HF) prior to aluminum
+deposition. A post-fabrication removal of the oxides on the surface of the
+silicon substrate and the aluminum film by immersion in HF further improves the
+$Q_i$. We observe a small, but noticeable, adverse effect on the loss by
+omitting either standard cleaning (SC1), pre-deposition heating of the
+substrate to 300$\deg$C, or in-situ post-deposition oxidation of the film's top
+surface. We find no improvement due to excessive pumping meant to reach a
+background pressure below $6{\times} 10^{-8}$ mbar. We correlate the measured
+loss with microscopic properties of the substrate-metal interface through
+characterization with X-ray photoelectron spectroscopy (XPS), time-of-flight
+secondary ion mass spectroscopy (ToF-SIMS), transmission electron microscopy
+(TEM), energy-dispersive X-ray spectroscopy (EDS), and atomic force microscopy
+(AFM).",2403.00723v1
+2024-03-06,The Geochemical Potential for Metabolic Processes on the Sub-Neptune Exoplanet K2-18b,"Quantifying disequilibria is important to understand whether an environment
+could be habitable. It has been proposed that the exoplanet K2-18b has a
+hydrogen-rich atmosphere and a water ocean, making it a ""hycean world"". The
+James Webb Space Telescope recently made measurements of methane, CO$_2$, and
+possibly dimethyl sulfide (DMS) in the atmosphere of this planet. The initial
+interpretation of these data is that they may support the occurrence of hycean
+conditions. Here, I attempt to take a next step in exploring the prospects for
+habitability. I use constraints on the abundances of atmospheric gases to
+calculate how much chemical disequilibrium there could be, assuming K2-18b is a
+hycean world. I find that the presence of oxidized carbon species coexisting
+with abundant H$_2$ (1-1000 bar) at cool to warm (25-120{\deg}C) conditions
+creates a strong thermodynamic drive for methanogenesis. More than ~75 kJ (mol
+C)$^{-1}$ of free energy can be released from CO$_2$ hydrogenation. Partially
+oxidized carbon compounds such as DMS (if present) also have potential to
+provide metabolic energy, albeit in smaller quantities. Because of the
+thermodynamic instability of CO$_2$ under hycean conditions, other reductive
+reactions of CO$_2$ are likely to be favored, including the synthesis of amino
+acids. Glycine and alanine synthesis can be energy-releasing or at least much
+less costly on K2-18b than in Earth's ocean, even when NH$_3$ is scarce but not
+totally absent. These first bioenergetic calculations for a proposed
+ocean-bearing exoplanet lay new groundwork for assessing exoplanetary
+habitability.",2403.03918v1
+2024-03-13,Highly confined epsilon-near-zero- and surface-phonon polaritons in SrTiO3 membranes,"Recent theoretical studies have suggested that transition metal perovskite
+oxide membranes can enable surface phonon polaritons in the infrared range with
+low loss and much stronger subwavelength confinement than bulk crystals. Such
+modes, however, have not been experimentally observed so far. Here, using a
+combination of far-field Fourier-transform infrared (FTIR) spectroscopy and
+near-field synchrotron infrared nanospectroscopy (SINS) imaging, we study the
+phonon-polaritons in a 100 nm thick freestanding crystalline membrane of SrTiO3
+transferred on metallic and dielectric substrates. We observe a
+symmetric-antisymmetric mode splitting giving rise to epsilon-near-zero and
+Berreman modes as well as highly confined (by a factor of 10) propagating
+phonon polaritons, both of which result from the deep-subwavelength thickness
+of the membranes. Theoretical modeling based on the analytical finite-dipole
+model and numerical finite-difference methods fully corroborate the
+experimental results. Our work reveals the potential of oxide membranes as a
+promising platform for infrared photonics and polaritonics.",2403.08500v1
+2024-03-25,Recent advances on CO2-assisted synthesis of metal nanoparticles for the upgrading of biomass-derived compounds,"Nanostructured catalysts have attracted the increased attention for biomass
+conversion into high-valued chemicals due to the rapid depletion of fossil
+resources and increasingly severe environmental issues. Supercritical carbon
+dioxide (scCO2) fluid is an attractive medium for synthesizing nanostructured
+materials due to its favorable properties. In this review, the properties of
+scCO2 and the roles of scCO2 in the fabrication of metal nanoparticles were
+assessed in detailed. A general overview of the synthesis of different types of
+metal nanoparticles (including metal oxide nanoparticles) using scCO2 and the
+relationship between the structure of the obtained metal nanoparticles and the
+preparation conditions such as reaction temperature and pressure, types of
+metal precursors, and deposition time are system summarized and compared in
+tables. Besides, compared to the meatal catalysts using the conventional
+methods, the catalysts obtained using scCO2 exhibited excellent catalytic
+performance on biomass conversion reactions, mainly focused on oxidation,
+hydrogenation reactions. Finally, opportunities and challenges of metal
+nanoparticle preparation using scCO2 for biomass valorization to chemicals and
+liquid fuels are highlighted. This review could be helpful for the rational
+design of more efficient metal catalysts for the selective synthesis of fine
+chemicals and fuels from biomass-derived chemicals.",2403.16751v1
+2024-03-26,Recent advances on the spherical metal oxides for sustainable degradation of antibiotics,"Due to the permanent harm to human health and ecosystem balance, antibiotic
+pollution in water has become an important direction of current environmental
+governance. Spherical metal oxides (SMOs) have been frequently utilized as
+effective heterogeneous photocatalysts for the efficient degradation of
+antibiotics due to the unique properties (e.g., strong light absorption
+ability, high separation efficiency of photo-generated electron hole pairs, and
+good catalytic activity). This review will firstly focus on summarizing the
+rational design and synthesis of SMOs with various tuned microstructures such
+as hollow, porous shell, yolk shell, core shell, and nanoflowers. These
+structures can expose more active sites, achieve a higher utilization rate of
+light, enhance the mass transfer efficiency and improve the effective diffusion
+of reactive oxygen species (ROS). Secondly, this review will mainly analyze the
+intrinsic relationship between the structure of SMOs and its photocatalytic
+property, the ability to generate ROS, and the degradation pathway for
+antibiotics. Moreover, the photocatalytic mechanisms and recent progress of
+different SMOs catalysts for degrading typical antibiotics are compared in
+detail. Finally, challenges and prospects of future direction in the
+development of SMOs for antibiotic degradation are reviewed. It is expected to
+provide a rational design of SMOs catalysts for efficient photocatalytic
+degradation of environmental pollutants.",2403.17316v1
+2002-05-12,The Role of Magnetic Helicity Transport in Nonlinear Galactic Dynamos,"We consider the magnetic helicity balance for the galactic dynamo in the
+framework of the local dynamo problem, as well as in the no-z model (which
+includes explicitly the radial distribution of the magnetic fields). When
+calculating the magnetic helicity balance we take into account the
+redistribution of the small-scale and large-scale magnetic fields between the
+magnetic helicities, as well as magnetic helicity transport and diffusion due
+to small-scale turbulence. We demonstrate that the magnetic helicity flux
+through the galactic disc boundaries leads to a steady-state magnetic field
+with magnetic energy comparable to the equipartition energy of the turbulent
+motions of the interstellar medium. If such flux is ignored, the steady-state
+magnetic field is found to be much smaller than the equipartition field. The
+total magnetic helicity flux through the boundaries consists of both an
+advective flux and a diffusive flux. The exact ratio of these contributions
+seems not to be crucial for determining the strength of the steady-state
+magnetic field and its structure. However at least some diffusive contribution
+is needed to smooth the magnetic helicity profile near to the disc boundaries.
+The roles of various transport coefficients for magnetic helicity are
+investigated, and the values which lead to magnetic field configurations
+comparable with those observed are determined.",0205165v1
+2004-01-22,The magnetic field of pulsars and the gravito-magnetic theory,"Many authors have considered a gravitational origin of the magnetic field of
+celestial bodies. Especially, the so-called Wilson-Blackett formula has been
+investigated, both theoretically and observationally. It appeared possible to
+deduce this formula from general relativity, e. g., by application of a special
+interpretation of gravito-magnetic theory. More consequences of the latter
+theory for pulsars will be considered in this work. As an example, the standard
+quadrupolar charge density for pulsars can be deduced from the gravito-magnetic
+theory. Moreover, a new magnetic dipole moment from electromagnetic origin is
+found, generated in the basic magnetic field from gravito-magnetic origin. In
+general, for thirteen accreting, slowly rotating, binary pulsars the agreement
+between the observed magnetic field and the gravito-magnetic prediction is
+better than between the observed value and the value from the standard magnetic
+dipole radiation model. At present, an analogous comparison for five isolated
+pulsars appears to be difficult. For a sample of 100 pulsars the averaged
+(gravito-)magnetic field, extracted from the magnetic dipole spin-down model,
+is in fair agreement with the gravito-magnetic prediction. Unfortunately, the
+(gravito-)magnetic field has not yet directly been measured. Finally, it is
+found that the first and second order braking indices only depend on the
+magnetic field from electromagnetic origin.",0401468v1
+2001-08-29,The Finite Energy Constant Magnetization of the Two - Dimensional Ising Model,"We suggest the new definition of the magnetization. For the two - dimensional
+Ising model with the free boundary conditions we calculate any derivative of
+this magnetization for zero magnetic field.",0108489v1
+2002-07-08,The Magnetization by the Finite Energy Constant Magnetic Field in the Two - Dimentional Ising Model,"We suggest the new definition of the magnetization. For the two - dimensional
+Ising model with the free boundary conditions we calculate this magnetization.",0207200v1
+2009-11-12,Coherent states in the presence of a variable magnetic field,"We introduce magnetic coherent states for a particle in a variable magnetic
+field. They provide a pure state quantization of the phase space R^{2N} endowed
+with a magnetic symplectic form.",0911.2451v1
+2010-06-07,Solitary Magnetic Bubbles,"Stability and attractor property of free-floating axisymmetric magnetic
+bubbles in high-conductivity plasmas is (tentatively, numerically)
+demonstrated. The existence of compact non-singular axisymmetric magnetic
+equilibria is proved. Being attractors, the solitary magnetic bubbles should
+exist in nature.",1006.1368v1
+2011-06-18,Magnetic curves corresponding to Killing magnetic fields in $E^3$,"We explicitly determine all magnetic curves corresponding to the Killing
+magnetic fields on the 3-dimensional Euclidean space.",1106.3673v1
+2012-09-27,Growth of a localized seed magnetic field in a turbulent medium,"Turbulence dynamo deals with amplification of a seed magnetic field in a
+turbulent medium and has been studied mostly for uniform or spatially
+homogeneous seed magnetic fields. However, some astrophysical processes (e.g.
+jets from active galaxies, galactic winds, or ram-pressure stripping in galaxy
+clusters) can provide localized seed magnetic fields. In this paper, we
+numerically study amplification of localized seed magnetic fields in a
+turbulent medium. Throughout the paper, we assume that driving scale of
+turbulence is comparable to the size of the system. Our findings are as
+follows. First, turbulence can amplify a localized seed magnetic field very
+efficiently. The growth rate of magnetic energy density is as high as that for
+a uniform seed magnetic field. This result implies that a magnetic field
+ejected from an astrophysical object can be a viable source of magnetic field
+in a cluster. Second, the localized seed magnetic field disperses and fills the
+whole system very fast. If turbulence in a system (e.g. a galaxy cluster or a
+filament) is driven at large scales, we expect that it takes a few large-eddy
+turnover times for magnetic field to fill the whole system. Third, growth and
+turbulence diffusion of a localized seed magnetic field are also fast in high
+magnetic Prandtl number turbulence. Fourth, even in decaying turbulence, a
+localized seed magnetic field can ultimately fill the whole system. Although
+the dispersal rate of magnetic field is not fast in purely decaying turbulence,
+it can be enhanced by an additional forcing.",1209.6130v1
+2013-01-28,Two-dimensional Ising model in a finite magnetic field for the square lattice of infinite sites-Partition function and Magnetization,"The partition function and magnetization equations are derived for the
+two-dimensional nearest neighbour Ising models in a magnetic field.",1302.1084v1
+2014-07-08,Competing magnetic phases and field-induced dynamics in DyRuAsO,"Analysis of neutron diffraction, dc magnetization, ac magnetic
+susceptibility, heat capacity, and electrical resistivity for DyRuAsO in an
+applied magnetic field are presented at temperatures near and below those at
+which the structural distortion (T_S = 25 K) and subsequent magnetic ordering
+(T_N = 10.5 K) take place. Powder neutron diffraction is used to determine the
+antiferromagnetic order of Dy moments of magnitude 7.6(1) mu_B in the absence
+of a magnetic field, and demonstrate the reorientation of the moments into a
+ferromagnetic configuration upon application of a magnetic field. Dy magnetism
+is identified as the driving force for the structural distortion. The magnetic
+structure of analogous TbRuAsO is also reported. Competition between the two
+magnetically ordered states in DyRuAsO is found to produce unusual physical
+properties in applied magnetic fields at low temperature. An additional phase
+transition near T* = 3 K is observed in heat capacity and other properties in
+fields greater than about 3 T. Magnetic fields of this magnitude also induce
+spin-glass-like behavior including thermal and magnetic hysteresis, divergence
+of zero-field-cooled and field-cooled magnetization, frequency dependent
+anomalies in ac magnetic susceptibility, and slow relaxation of the
+magnetization. This is remarkable since DyRuAsO is a stoichiometric material
+with no disorder detected by neutron diffraction, and suggests analogies with
+spin-ice compounds and related materials with strong geometric frustration.",1407.2184v1
+2017-03-30,Relative magnetic helicity as a diagnostic of solar eruptivity,"The discovery of clear criteria that can deterministically describe the
+eruptive state of a solar active region would lead to major improvements on
+space weather predictions. Using series of numerical simulations of the
+emergence of a magnetic flux rope in a magnetized coronal, leading either to
+eruptions or to stable configurations, we test several global scalar quantities
+for the ability to discriminate between the eruptive and the non-eruptive
+simulations. From the magnetic field generated by the three-dimensional
+magnetohydrodynamical simulations, we compute and analyse the evolution of the
+magnetic flux, of the magnetic energy and its decomposition into potential and
+free energies, and of the relative magnetic helicity and its decomposition.
+Unlike the magnetic flux and magnetic energies, magnetic helicities are able to
+markedly distinguish the eruptive from the non-eruptive simulations. We find
+that the ratio of the magnetic helicity of the current-carrying magnetic field
+to the total relative helicity presents the highest values for the eruptive
+simulations, in the pre-eruptive phase only. We observe that the eruptive
+simulations do not possess the highest value of total magnetic helicity. In the
+framework of our numerical study, the magnetic energies and the total relative
+helicity do not correspond to good eruptivity proxies. Our study highlights
+that the ratio of magnetic helicities diagnoses very clearly the eruptive
+potential of our parametric simulations. Our study shows that
+magnetic-helicity-based quantities may be very efficient for the prediction of
+solar eruptions.",1703.10562v1
+2018-11-30,Double bit in-plane magnetic skyrmions on a track,"A magnetic skyrmion isusually refers to a twisted spin texture surrounded by
+uniformly aligned out-of-plane spinsin the background of a uniformly magnetized
+state. The invariance of the magnetic skyrmion conserves its topological charge
+under any continuous transformations of the spin textures, leads to which
+represents the robustness of a magnetic skyrmion their texture against external
+perturbations, making it ideal to use skyrmions as . Such a behaviour is
+required for an ideal information carriers. To date, most magnetic skyrmion
+studies have been performedfocused on in perpendicularly magnetized systems,
+where the skyrmion topological number is determined by the relative orientation
+between the core and /outer perpendicular magnetization directions of the
+skyrmion is either up/down or down/up. Here we show that there also exists a
+new type of magnetic skyrmion with surrounding spins to be uniformly aligned to
+the in-plane direction. By continuous transformation and relaxation of the spin
+textures of out-of-plane skyrmions, we showed that an in-plane skyrmion, where
+the background magnetization is in the in-plane direction, is also possible.
+Different from the conventional perpendicular magnetic skyrmionsContrary to the
+skyrmions in a perpendicularly magnetized state, the in-plane magnetic
+skyrmions with opposite signs of topological charges can inherentlycharges can
+inherently coexist in the in-plane magnetization system coexist. Moreover, the
+iIn-plane skyrmions of opposite charge can move together by an electric current
+and exhibit with an opposite spin Hall effect. These findings showdemonstrate
+the inherent possibility of a double-bit transfer in a single magnetic wire
+that is not possible in a perpendicularly magnetized system.",1811.12552v1
+2020-07-26,Effect of the anomalous magnetic moment of quarks on magnetized QCD matter and meson spectra,"We systematically investigate the effect of the anomalous magnetic
+moment(AMM) of quarks on the magnetized QCD matter, including the magnetic
+susceptibility, the inverse magnetic catalysis around the critical temperature
+and the neutral/charged pion and rho meson spectra under magnetic fields. The
+dynamical AMM of quarks, its coupling with magnetic field causes Zeeman
+splitting of the dispersion relation of quarks thus changes the magnetism
+properties and meson mass spectra under magnetic fields. It is found that
+including the AMM of quarks cannot fully understand lattice results of the
+magnetized matter: The AMM of quarks reduces the dynamical quark mass thus
+causes the inverse magnetic catalysis around $T_c$. The neutral pion mass is
+very sensitive to the AMM, it decreases with magnetic field quickly, and the
+charged pion mass shows a nonlinear behavior, i.e., firstly linearly increases
+with the magnetic field and then saturates at strong magnetic field. For rho
+meson, it is observed that AMM reduces the mass of neutral rho meson mass with
+different $s_z$, and reduces the mass of $s_z=+1,0$ component charged rho meson
+mass but enhances the $s_z=-1$ component charged rho meson mass. The magnetic
+susceptibility at low temperature can be either positive or negative with
+different AMM.",2007.13122v3
+2012-01-13,Development for Hardware for Programming of Spatial Magnetic Field Distributions in Nuclear Magnetic Resonance and Magnetic Resonance Imaging,"The proposal of a project aimed on a design of hardware for programming 3D
+Magnetic Field shapes over sample volume in NMR and MRI is described.",1201.2764v1
+2016-08-16,Magnetic Dirichlet Laplacian with radially symmetric magnetic field,"The aim of the paper is to derive spectral estimates on the eigenvalue
+moments of the magnetic Dirichlet Laplacian defined on the two-dimensional disk
+with a radially symmetric magnetic field.",1608.04555v1
+2017-12-26,Evolution of Relative Magnetic Helicity: New Boundary Conditions for the Vector Potential,"We recently proposed a method to calculate the relative magnetic helicity in
+a finite volume for a given magnetic field which however required the flux to
+be balanced separately on all the sides of the considered volume. In order to
+allow finite magnetic fluxes through the boundaries, a Coulomb gauge is
+constructed that allows for global magnetic flux balance. We tested and
+verified our method in a theoretical fore-free magnetic field model. We apply
+the new method to the former calculation data and found a difference of less
+than 1.2\%. We also applied our method to the magnetic field above active
+region NOAA 11429 obtained by a new photospheric-data-driven MHD model code
+GOEMHD3. We analyzed the magnetic helicity evolution in the solar corona using
+our new method. It was found that the normalized magnetic helicityis equal to
+-0.038 when fast magnetic reconnection is triggered. This value is comparable
+to the previous value (-0.029) in the MHD simulations when magnetic
+reconnection happened and the observed normalized magnetic helicity (-0.036)
+from the eruption of newly emerging active regions. We found that only 8\% of
+the accumulated magnetic helicity is dissipated after it is injected through
+the bottom boundary. This is in accordance with the Woltjer conjecture. Only
+2\% of magnetic helicity injected from the bottom boundary escapes through the
+corona. This is consistent with the observation of magnetic clouds, which could
+take away magnetic helicity into the interplanetary space, in the case
+considered here, several halo CMEs and two X-class solar flares origin from
+this active region.",1712.09219v1
+2019-10-13,A systematically study of thermal width of heavy quarkonia in a finite temperature magnetized background from holography,"By simulating the finite temperatures magnetized background in the RHIC and
+LHC energies, we systematically study the characteristics of thermal widths and
+potentials of heavy quarkonia. It is found that the magnetic field has less
+influence on the real potential, but has a significant influence on the
+imaginary potential, especially in the low deconfined temperature. Extracted
+from the effect of thermal worldsheet fluctuations about the classical
+configuration, the thermal width of $\Upsilon(1s)$ in the finite temperature
+magnetized background is investigated. It is found that at the low deconfined
+temperature the magnetic field can generate a significant thermal fluctuation
+of the thermal width of $\Upsilon(1s)$, but with the increase of temperature,
+the effect of magnetic field on the thermal width becomes less important, which
+means the effect of high temperature completely exceeds that of magnetic field
+and magnetic field become less important at high temperature. The thermal width
+decreases with the increasing rapidity at the finite temperature magnetized
+background. It is also observed that the effect of the magnetic field on the
+thermal width when dipole moving parallel to the magnetic field direction are
+larger than that moving perpendicular to the magnetic field direction, which
+implies that the magnetic field tends to enhance thermal fluctuation when
+dipole moving parallel to the direction of magnetic field. The thermal width of
+$\Upsilon(1S)$ hardly changes with the increasing temperature when dipole
+moving perpendicular to the magnetic field. But when dipole moving parallel to
+the magnetic field, the thermal width at low temperature is obviously larger
+than that at high temperature.",1910.05668v1
+2017-05-17,Magnetic Transport in Spin Antiferromagnets for Spintronics Applications,"Had magnetic monopoles been ubiquitous as electrons are, we would probably
+have had a different form of matter, and power plants based on currents of
+these magnetic charges would have been a familiar scene of modern technology.
+Magnetic dipoles do exist, however, and in principle one could wonder if we can
+use them to generate magnetic currents. In the present work, we address the
+issue of generating magnetic currents and magnetic thermal currents in
+electrically-insulating low-dimensional Heisenberg antiferromagnets by invoking
+the (broken) electricity-magnetism duality symmetry. The ground state of these
+materials is a spin-liquid state that can be described well via~the
+Jordan--Wigner fermions, which permit an easy definition of the magnetic
+particle and thermal currents. The magnetic and magnetic thermal conductivities
+are calculated in the present work using the bond--mean field theory. The
+spin-liquid states in these antiferromagnets are either gapless or gapped
+liquids of spinless fermions whose flow defines a current just as the one
+defined for electrons in a Fermi liquid. The driving force for the magnetic
+current is a magnetic field with a gradient along the magnetic conductor. We
+predict the generation of a magneto-motive force and realization of magnetic
+circuits using low-dimensional Heisenberg antiferromagnets. The present work is
+also about claiming that what the experiments in spintronics attempt to do is
+trying to treat the magnetic degrees of freedoms on the same footing as the
+electronic ones.",1705.06318v2
+2020-03-18,On the saturation mechanism of the fluctuation dynamo at ${\text{Pr}_\mathrm{M}} \ge 1$,"The presence of magnetic fields in many astrophysical objects is due to
+dynamo action, whereby a part of the kinetic energy is converted into magnetic
+energy. A turbulent dynamo that produces magnetic field structures on the same
+scale as the turbulent flow is known as the fluctuation dynamo. We use
+numerical simulations to explore the nonlinear, statistically steady state of
+the fluctuation dynamo in driven turbulence. We demonstrate that as the
+magnetic field growth saturates, its amplification and diffusion are both
+affected by the back-reaction of the Lorentz force upon the flow. The
+amplification of the magnetic field is reduced due to stronger alignment
+between the velocity field, magnetic field, and electric current density.
+Furthermore, we confirm that the amplification decreases due to a weaker
+stretching of the magnetic field lines. The enhancement in diffusion relative
+to the field line stretching is quantified by a decrease in the computed local
+value of the magnetic Reynolds number. Using the Minkowski functionals, we
+quantify the shape of the magnetic structures produced by the dynamo as
+magnetic filaments and ribbons in both kinematic and saturated dynamos and
+derive the scalings of the typical length, width, and thickness of the magnetic
+structures with the magnetic Reynolds number. We show that all three of these
+magnetic length scales increase as the dynamo saturates. The magnetic
+intermittency, strong in the kinematic dynamo (where the magnetic field
+strength grows exponentially) persists in the statistically steady state, but
+intense magnetic filaments and ribbons are more volume-filling.",2003.07997v1
+2021-09-03,"Investigating the Magnetic Field outside small Accelerator Magnet Analogs via Experiment, Simulation, and Theory","Particle accelerators use powerful and complex magnetic fields to turn,
+shape, and eventually collide beams of near-light-speed particles, yet the
+fundamental magnetic principles behind the accelerator magnets can be
+understood by undergraduate students. In this paper we use small-scale
+accelerator magnet analogs in a multi-faceted, low-cost exploration of the
+magnetic field exterior to accelerator magnets. These fields are best
+understood using the multipole expansion of the field. If we assume that the
+magnetic field is created by ideal magnetic dipoles, we can derive a
+theoretical model that shows that each accelerator magnet configuration is
+dominated by a single multipole moment and obeys $B \propto 1/r^{l+2}$, where
+$l$ is the multipole order (with $l = 1, 2, 3, 4$ for the dipole, quadrupole,
+octopole, and hexadecapole moments, respectively). Using commercially available
+NdFeB magnets and the magnetic field sensor inside a smartphone, we
+experimentally verify the power-law dependence of the accelerator magnet
+configurations. Finally, we use the open-source Python library Magpylib to
+simulate the magnetic field of the permanent magnet configurations, showing
+good agreement between theory, experiment, and simulation.",2109.03057v4
+2021-12-02,Heisenberg representation of nonthermal ultrafast laser excitation of magnetic precessions,"We derive the Heisenberg representation of the ultrafast inverse Faraday
+effect that provides the time evolution of magnetic vectors of a magnetic
+system during its interaction with a laser pulse. We obtain a time-dependent
+effective magnetic operator acting in the Hilbert space of the total angular
+momentum that describes a process of nonthermal excitation of magnetic
+precessions in an electronic system by a circularly polarized laser pulse. The
+magnetic operator separates the effect of the laser pulse on the magnetic
+system from other magnetic interactions. The effective magnetic operator
+provides the equations of motion of magnetic vectors during the excitation by
+the laser. We show that magnetization dynamics calculated with these equations
+is equivalent to magnetization dynamics calculated with the time-dependent
+Schr\""odinger equation, which takes into account the interaction of an
+electronic system with the electric field of light. We model and compare
+laser-induced precessions of magnetic sublattices of an easy-plane and an
+easy-axis antiferromagnetic systems. Using these models, we show how the
+ultrafast inverse Faraday effect induces a net magnetic moment in
+antiferromagnets and demonstrate that a crystal field environment and the
+exchange interaction play essential roles for laser-induced magnetization
+dynamics even during the action of a pump pulse. Using our approach, we show
+that light-induced precessions can start even during the action of the pump
+pulse with a duration several tens times shorter than the period of induced
+precessions and affect the position of magnetic vectors after the action of the
+pump pulse.",2112.01350v1
+2022-07-20,Hot magnetic halo of NGC628 (M74),"In several spiral galaxies that are observed face-on, large-scale ordered
+magnetic fields (the so-called magnetic arms) were found. One of the
+explanations was the action of the magnetic reconnection, which leads to a
+higher ordering of the magnetic fields. Because it simultaneously converts the
+energy of the magnetic fields into thermal energy of the surroundings, magnetic
+reconnection has been considered as a heating mechanism of the interstellar
+medium for many years. Until recently, no clear observational evidence for this
+phenomenon was found. We search for possible signatures of gas heating by
+magnetic reconnection effects in the radio and X-ray data for the face-on
+spiral galaxy NGC628 (M74), which presents pronounced magnetic arms and
+evidence for vertical magnetic fields. The strengths and energy densities of
+the magnetic field in the spiral and magnetic arms were derived, as were the
+temperatures and thermal energy densities of the hot gas, for the disk and halo
+emission. In the regions of magnetic arms, higher order and lower energy
+density of the magnetic field is found than in the stellar spiral arms. The
+global temperature of the hot gas is roughly constant throughout the disk. The
+comparison of the findings with those obtained for the starburst galaxy M83
+suggests that magnetic reconnection heating may be present in the halo of
+NGC628. The joint analysis of the properties of the magnetic fields and the hot
+gas in NGC628 also provided clues for possible tidal interaction with the
+companion galaxy.",2207.09917v1
+2022-09-07,Atypical magnetic behavior in the incommensurate $[CH_3NH_3][Ni(HCOO)_3]$ hybrid perovskite,"A plethora of temperature induced phase transitions have been observed in
+$[CH_3NH_3][M(HCOO)_3]$ compounds, where M is Co(II) or Ni(II). Among them, the
+nickel compound exhibits a combination of magnetic and nuclear
+incommensurabil-ity below N\'eel temperature. Despite the fact that the
+zero-field behavior has been previously addressed, here we study in depth the
+macroscopic magnetic behavior of this compound to unveil the origin of the
+atypical magnetic response found in it and in its parent family of formate
+perovskites. In particular, they show a puzzling magnetization reversal in the
+curves measured starting from low temperatures, after cooling under zero field.
+The first atypical phenomena is the im-possibility of reaching zero
+magnetization, even by nullifying the applied external field and even
+compensating it for the influence earth's magnetic field. Relatively large
+magnetic fields are needed to switch the magnetization from negative to
+positive values or vice versa, which is compatible with a soft-ferromagnetic
+system. The atypical path found in its first magnetization curve and hysteresis
+loop at low temperatures is the most noticeable feature. The magnetization
+curve switches from more than 1200 Oe from the first magnetization loop to the
+subsequent magnetization loops. A feature that cannot be explained using a
+model based on unbalanced pair of domains. As a result, we decipher this
+behavior in light of the incommensurate structure of this material. We propose,
+in particular, that the applied magnetic field induces a mag-netic phase
+transition from a magnetically incommensurate structure to a magnetically
+commensurate structure.",2209.03093v1
+2022-12-02,A promising formation channel for symbiotic X-ray binaries: cases of IGR J17329-2731 and 4U 1700+24,"Recent observations demonstrate that the symbiotic X-ray binary (SyXB) IGR
+J17329-2731 contains a highly magnetized neutron star (NS) which accretes
+matter through the wind from its giant star companion, and suggest that 4U
+1700+24 may also have a highly magnetized NS. Accretion-induced collapse (AIC)
+from oxygen-neon-magnesium white dwarf (ONeMg WD) + red giant (RG) star
+binaries is one promising channel to form these SyXBs, while other long
+standing formation channels have difficulties to produce these SyXBs. By
+considering non-magnetic and magnetic ONeMg WDs, I investigate the evolution of
+ONeMg WD + RG binaries with the MESA stellar evolution code for producing SyXBs
+with non-magnetic or magnetized NSs. In the pre-AIC evolution with magnetic
+confinement, the mass accumulation efficiency of the accreting WD is increased
+at low mass transfer rate compared to the non-magnetic case. The newborn NSs
+formed via AIC of highly magnetized WDs could inherit the large magnetic field
+through conservation of magnetic flux, and the systems could have a long age
+compatible with that of the red giant companions. These young and highly
+magnetized NSs could accrete matters from the stellar wind of the giant
+companions to that shine as those observed SyXBs, and could preserve their high
+magnetic field during this time. The MESA calculation results show that the
+initial parameter (initial RG mass and orbital period) space for the AIC with
+magnetic confinement to form SyXBs with highly magnetized NSs shifts to be
+lower and narrower compared to that of the no magnetic confinement case.",2212.00997v2
+2023-07-28,Reversible magnetic domain reorientation induced by magnetic field pulses with fixed direction,"Nanoscale magnetic domains with controllable configurations could be used for
+classical and quantum applications, where the switching of magnetization
+configurations is an essential operation for information processing. Here, we
+report that the magnetic domain reorientation in a notched ferromagnetic
+nanotrack can be realized and effectively controlled by applying uniform
+magnetic field pulses in a fixed in-plane direction perpendicular to the
+nanotrack. Our micromagnetic simulation results show that the configurations of
+magnetic domains in the notched nanotrack can be switched between a
+head-to-head state and a tail-to-tail state in a reversible manner driven by
+magnetic field pulses, while it is unnecessary to reverse the direction of the
+magnetic field. Such a unique magnetic domain reorientation dynamics is found
+to depend on magnetic parameters and nanotrack geometries. The reorientation
+dynamics of magnetic domains also depends on the strength and length of the
+applied magnetic field pulse. In addition, we point out that the notches at the
+center of the nanotrack play an important role for the stabilization of the
+head-to-head and tail-to-tail states during the magnetic domain reorientation.
+We also qualitatively explain the field-induced reorientation phenomenon with a
+simplified two-dimensional macrospin model. Our results may make it possible to
+build spintronic devices driven by a fixed magnetic field. Our findings may
+also motivate future studies to investigate the classical and quantum
+applications based on nanoscale magnetic domains.",2307.15263v1
+2023-09-14,Disentangling the Entangled Linkages of Relative Magnetic Helicity,"Magnetic helicity, $H$, measures magnetic linkages in a volume. The early
+theoretical development of helicity focused on magnetically closed systems in
+$\mathcal{V}$ bounded by $\mathcal{S}$. For magnetically closed systems,
+$\mathcal{V}\in\mathbb{R}^3=\mathcal{V}+\mathcal{V}^*$, no magnetic flux
+threads the boundary, $\hat{\boldsymbol{n}}\cdot\boldsymbol{B}|_\mathcal{S}=0$.
+Berger and Field (1984) and Finn and Antonsen (1985) extended the definition of
+helicity to relative helicity, $\mathcal{H}$, for magnetically open systems
+where magnetic flux may thread the boundary. Berger (1999,2003) expressed this
+relative helicity as two gauge invariant terms that describe the self helicity
+of magnetic field that closes inside $\mathcal{V}$ and the mutual helicity
+between the magnetic field that threads the boundary $\mathcal{S}$ and the
+magnetic field that closes inside $\mathcal{V}$. The total magnetic field that
+permeates $\mathcal{V}$ entangles magnetic fields that are produced by current
+sources $\boldsymbol{J}$ in $\mathcal{V}$ with magnetic fields that are
+produced by current sources $\boldsymbol{J}^*$ in $\mathcal{V}^*$. Building on
+this fact, we extend Berger's expressions for relative magnetic helicity to
+eight gauge invariant quantities that simultaneously characterize both of these
+self and mutual helicities and attribute their origins to currents
+$\boldsymbol{J}$ in $\mathcal{V}$ and/or $\boldsymbol{J}^*$ in $\mathcal{V}^*$,
+thereby disentangling the domain of origin for these entangled linkages. We
+arrange these eight terms into novel expressions for internal and external
+helicity (self) and internal-external helicity (mutual) based on their domain
+of origin. The implications of these linkages for interpreting magnetic energy
+is discussed and new boundary observables are proposed for tracking the
+evolution of the field that threads the boundary.",2309.07776v1
+2024-03-23,Engineering the electronic and magnetic properties of monolayer TiS$_2$ through systematic transition-metal doping,"Layered materials that exhibit magnetic ordering in their pristine form are
+very rare. Several standard approaches, such as adsorption of atoms,
+introduction of point defects, and edge engineering, have been developed to
+induce magnetism in two-dimensional materials. In this way, we investigate the
+electronic and magnetic properties of monolayer TiS$_2$ doped with 3$d$
+transition metals (TMs) atoms in both octahedral 1T and trigonal prismatic 1H
+structures using first-principles calculations. In its pristine form, TiS$_2$
+is a non-magnetic semiconductor. The bands near the Fermi energy primarily
+exhibit $d$ orbital characters, and due to the presence of ideal octahedral and
+trigonal arrangements, they are well separated from other bands with $p$
+character. Upon substituting 3$d$-TM atoms in both structures, a variety of
+electronic and magnetic phases emerge, including magnetic semiconductor,
+magnetic half-metal, non-magnetic metal, and magnetic metal. Chromium exhibits
+the largest magnetic moment in both the 1T and 1H structures. The 1T structure
+shows a slightly higher magnetic moment of 3.419 $\mu_B$ compared to the 1H
+structure 3.138 $\mu_B$, attributed to the distorted octahedral structure of
+the 1T structure. Unlike pristine TiS$_2$, the deficiency in saturation of
+neighboring S atoms in the presence of impurities leads to the proximity of
+energy levels of $d$ and $p$ states, resulting in unexpectedly sizable magnetic
+moments. Another interesting case is Cobalt, which leads to a magnetic moment
+of approximately 0.805 $\mu_B$ in the 1H structure, while the Co exhibits a
+non-magnetic state in the 1H structure. These materials demonstrate a high
+degree of tunability and can be optimized for various magnetic applications.",2403.15850v1
+2003-05-06,How Spectral Shapes of Magnetic Energy and Magnetic Helicity Influence their Respective Decay Time Scales,"It is shown that in magnetohydrodynamics, the shapes of the magnetic energy
+and magnetic helicity spectra can influence whether the magnetic helicity
+resistive dissipation time scale is longer, equal to, or shorter than that of
+magnetic energy. The calculations highlight that magnetic helicity need not
+always dissipate significantly more slowly than magnetic energy. While this may
+be implicitly understood in detailed studies of magnetic helicity in plasma
+devices, it is not sufficiently emphasized in elementary discussions comparing
+magnetic helicity vs. magnetic energy evolution. Measuring magnetic energy and
+helicity decay times may provide a posteriori insight into the initial spectra.",0305069v2
+1999-11-03,Magnetic properties of submicron Co islands and their use as artificial pinning centers,"We report on the magnetic properties of elongated submicron magnetic islands
+and their influence on a superconducting film. The magnetic properties were
+studied by magnetization hysteresis loop measurements and scanning-force
+microscopy. In the as-grown state, the islands have a magnetic structure
+consisting of two antiparallel domains. This stable domain configuration has
+been directly visualized as a 2x2-checkerboard pattern by magnetic-force
+microscopy. In the remanent state, after magnetic saturation along the easy
+axis, all islands have a single-domain structure with the magnetic moment
+oriented along the magnetizing field direction. Periodic lattices of these Co
+islands act as efficient artificial pinning arrays for the flux lines in a
+superconducting Pb film deposited on top of the Co islands. The influence of
+the magnetic state of the dots on their pinning efficiency is investigated in
+these films, before and after the Co dots are magnetized.",9911034v1
+2000-04-26,Magnetic relaxation and magnetization field dependence measurements in La0.5Ca0.5MnO3,"We reported a systematic change in the average magnetic relaxation rate,
+after the application and removal of a 5 T magnetic field, in a polycrystalline
+sample of La0.5Ca0.5MnO3. Magnetic relaxation measurements and magnetization
+versus field curves were taken from 10 K to 160 K. The long time behavior of
+the relaxation curves was approximately logarithmic in all cases. Keywords:
+Charge Ordering, Relaxation, Magnetic measurements",0004460v2
+2004-08-30,Optical Studies of Zero-Field Magnetization of CdMnTe Quantum Dots: Influence of Average Size and Composition of Quantum Dots,"We show that through the resonant optical excitation of spin-polarized
+excitons into CdMnTe magnetic quantum dots, we can induce a macroscopic
+magnetization of the Mn impurities. We observe very broad (4 meV linewidth)
+emission lines of single dots, which are consistent with the formation of
+strongly confined exciton magnetic polarons. Therefore we attribute the
+optically induced magnetization of the magnetic dots results to the formation
+of spin-polarized exciton magnetic polarons. We find that the photo-induced
+magnetization of magnetic polarons is weaker for larger dots which emit at
+lower energies within the QD distribution. We also show that the photo-induced
+magnetization is stronger for quantum dots with lower Mn concentration, which
+we ascribe to weaker Mn-Mn interaction between the nearest neighbors within the
+dots. Due to particular stability of the exciton magnetic polarons in QDs,
+where the localization of the electrons and holes is comparable to the magnetic
+exchange interaction, this optically induced spin alignment persists to
+temperatures as high as 160 K.",0408658v1
+2005-04-23,New Method to Calculate the Sign and Relative Strength of Magnetic Interactions in Low-Dimensional Systems on the Basis of Structural Data,"The connection of strength of magnetic interactions and type ordering the
+magnetic moments with crystal chemical characteristics in low-dimensional
+magnets is investigated. The new method to calculate the sign and relative
+strength of magnetic interactions in low-dimensional systems on the basis of
+the structural data is proposed. This method allows to estimate magnetic
+interactions not only inside low-dimensional fragments but also between them,
+and also to predict the possibility of the occurrence of magnetic phase
+transitions and anomalies of the magnetic interactions. Moreover, it can be
+used for search of low-dimensional magnets among the compounds whose crystal
+structures are known. The possibilities of the method are illustrated in an
+example of research of magnetic interactions in familiar low-dimensional
+magnets SrCu2(BO3)2, CaCuGe2O6, CaV4O9, Cu2Te2O5Cl2, Cu2Te2O5Br2, BaCu2Si2O7,
+BaCu2Ge2O7, BaCuSi2O6, LiCu2O2, and NaCu2O2.",0504599v3
+2005-10-21,Magnetostrictive hysteresis of TbCo/CoFe multilayers and magnetic domains,"Magnetic and magnetostrictive hysteresis loops of TbCo/CoFe multilayers under
+field applied along the hard magnetization axis are studied using vectorial
+magnetization measurements, optical deflectometry and magneto optical Kerr
+microscopy. Even a very small angle misalignment between hard axis and magnetic
+field direction is shown to drastically change the shape of magnetization and
+magnetostrictive torsion hysteresis loops. Two kinds of magnetic domains are
+revealed during the magnetization: big regions with opposite rotation of
+spontaneous magnetization vector and spontaneous magnetic domains which appear
+in a narrow field interval and provide an inversion of this rotation.
+  We show that the details of the hysteresis loops of our exchange-coupled
+films can be described using the classical model of homogeneous magnetization
+rotation of single uniaxial films and the configuration of observed domains.
+The understanding of these features is crucial for applications (for MEMS or
+microactuators) which benefit from the greatly enhanced sensitivity near the
+point of magnetic saturation at the transverse applied field.",0510568v1
+2006-02-14,Semiclassical pseudodifferential calculus and the reconstruction of a magnetic field,"We give a procedure for reconstructing a magnetic field and electric
+potential from boundary measurements related to the magnetic Schroedinger
+operator in three and higher dimensions.",0602290v1
+1999-01-29,Gravimetric Measurement of Magnetic Field Gradient Spatial Distribution,"Magnetic interaction between a weighing sample and an external magnetic field
+allows to measure characteristics of magnetic field (a sample with known
+magnetic characteristics), as well as the magnetic properties of a sample (a
+known magnetic field). Measurement of materials magnetic permeability is a well
+known application of this method. In this paper we restrict ourselves to the
+measurement of magnetic field spatial distribution, which was achieved by
+scanning of samples from known materials along the vertical axis. Field
+measurements by Hall detector were done to calibrate obtained data. Such
+measurements are of great interest in some branches of physics, in particular,
+in accelerator physics, where the quality of magnetic system parts eventually
+determine the quality of accelerated bunches. Development of a simple and cheep
+device for measurement of magnetic field spatial distribution is an urgent
+problem. The developed system for gravimetric measurement of magnetic field
+gradients partially solves this problem.",9901058v1
+1999-05-06,A Brief Note on Jupiter's Magnetism,"A recent model which gives the contribution of the earth's solid core to geo
+magnetism is seen to explain Jupiter's magnetism also.",9905014v1
+2008-01-30,How to use magnetic field information for coronal loop identification?,"The structure of the solar corona is dominated by the magnetic field because
+the magnetic pressure is about four orders of magnitude higher than the plasma
+pressure. Due to the high conductivity the emitting coronal plasma (visible
+e.g. in SOHO/EIT) outlines the magnetic field lines. The gradient of the
+emitting plasma structures is significantly lower parallel to the magnetic
+field lines than in the perpendicular direction. Consequently information
+regarding the coronal magnetic field can be used for the interpretation of
+coronal plasma structures. We extrapolate the coronal magnetic field from
+photospheric magnetic field measurements into the corona. The extrapolation
+method depends on assumptions regarding coronal currents, e.g. potential fields
+(current free) or force-free fields (current parallel to magnetic field). As a
+next step we project the reconstructed 3D magnetic field lines on an EIT-image
+and compare with the emitting plasma structures. Coronal loops are identified
+as closed magnetic field lines with a high emissivity in EIT and a small
+gradient of the emissivity along the magnetic field.",0801.4573v1
+2011-02-23,Possibility of conversion of neutron star to quark star in presence of high magnetic field,"Recent results and data suggests that high magnetic field in neutron stars
+(NS) strongly affects the characteristic (radius, mass) of the star. They are
+even separated as a class known as magnetars, for whom the surface magnetic
+field are greater than $10^{14}$ G. In this work we discuss the effect of such
+high magnetic field on the phase transition of NS to quark star (QS). We study
+the effect of magnetic field on the transition from NS to QS including the
+magnetic field effect in equation of state (EoS). The inclusion of the magnetic
+field increases the range of baryon number density, for which the flow
+velocities of the matter in the respective phase are finite. The magnetic field
+helps in initiation of the conversion process. The velocity of the conversion
+front however decreases due to the presence of magnetic field, as the presence
+of magnetic field reduces the effective pressure (P). The magnetic field of the
+star gets decreased by the conversion process, and the resultant QS has lower
+magnetic field than that of the initial NS.",1102.4660v2
+2011-03-06,"The Influence of Magnetic Anisotropy on the Kondo Effect and Spin-Polarized Transport through Magnetic Molecules, Adatoms and Quantum Dots","Transport properties in the Kondo regime of a nanosystem displaying uniaxial
+magnetic anisotropy (such as a magnetic molecule, magnetic adatom or quantum
+dot coupled to a localized magnetic moment) are analyzed theoretically. In
+particular, the influence of spin-polarized transport through a local orbital
+of the system and exchange coupling of conduction electrons to the system's
+magnetic core on the Kondo effect is discussed. The numerical renormalization
+group method is applied to calculate the spectral functions and linear
+conductance in the case of the parallel and antiparallel configurations of the
+electrodes' magnetic moments. It is shown that both the magnetic anisotropy as
+well as the exchange coupling between electrons tunneling through the
+conducting orbital and magnetic core play an important role in formation of the
+Kondo resonance, leading generally to its suppression. Specific transport
+properties of such a system appear also as a nontrivial behavior of tunnel
+magnetoresistance. It is also shown that the Kondo effect can be restored by an
+external magnetic field in both the parallel and antiparallel magnetic
+configurations.",1103.1128v2
+2011-03-18,Study of the interplay between magnetic shear and resonances using Hamiltonian models for the magnetic field lines,"The issue of magnetic confinement in magnetic fusion devices is addressed
+within a purely magnetic approach. Using some Hamiltonian models for the
+magnetic field lines, the dual impact of low magnetic shear is shown in a
+unified way. Away from resonances, it induces a drastic enhancement of magnetic
+confinement that favors robust internal transport barriers (ITBs) and
+stochastic transport reduction. When low-shear occurs for values of the winding
+of the magnetic field lines close to low-order rationals, the amplitude
+thresholds of the resonant modes that break internal transport barriers by
+allowing a radial stochastic transport of the magnetic field lines may be quite
+low. The approach can be applied to assess the robustness versus magnetic
+perturbations of general (almost) integrable magnetic steady states, including
+non-axisymmetric ones such as the important single helicity steady states. This
+analysis puts a constraint on the tolerable mode amplitudes compatible with
+ITBs and may be proposed as a possible explanation of diverse experimental and
+numerical signatures of their collapses.",1103.3595v1
+2014-08-05,Tunable asymmetric magnetoimpedance effect in ferromagnetic NiFe/Cu/Co films,"We investigate the magnetization dynamics through the magnetoimpedance effect
+in ferromagnetic NiFe/Cu/Co films. We observe that the magnetoimpedance
+response is dependent on the thickness of the non-magnetic Cu spacer material,
+a fact associated to the kind of the magnetic interaction between the
+ferromagnetic layers. Thus, we present an experimental study on asymmetric
+magnetoimpedance in ferromagnetic films with biphase magnetic behavior and
+explore the possibility of tuning the linear region of the magnetoimpedance
+curves around zero magnetic field by varying the thickness of the non-magnetic
+spacer material, and probe current frequency. We discuss the experimental
+magnetoimpedance results in terms of the different mechanisms governing the
+magnetization dynamics at distinct frequency ranges, quasi-static magnetic
+properties, thickness of the non-magnetic spacer material, and the kind of the
+magnetic interaction between the ferromagnetic layers. The results place
+ferromagnetic films with biphase magnetic behavior exhibiting asymmetric
+magnetoimpedance effect as a very attractive candidate for application as probe
+element in the development of auto-biased linear magnetic field sensors.",1408.0992v1
+2014-10-10,Comparison of adjustable permanent magnetic field sources,"A permanent magnet assembly in which the flux density can be altered by a
+mechanical operation is often significantly smaller than comparable
+electromagnets and also requires no electrical power to operate. In this paper
+five permanent magnet designs in which the magnetic flux density can be altered
+are analyzed using numerical simulations, and compared based on the generated
+magnetic flux density in a sample volume and the amount of magnet material
+used. The designs are the concentric Halbach cylinder, the two half Halbach
+cylinders, the two linear Halbach arrays and the four and six rod mangle. The
+concentric Halbach cylinder design is found to be the best performing design,
+i.e. the design that provides the most magnetic flux density using the least
+amount of magnet material. A concentric Halbach cylinder has been constructed
+and the magnetic flux density, the homogeneity and the direction of the
+magnetic field are measured and compared with numerical simulation and a good
+agreement is found.",1410.2681v1
+2014-11-25,Computing with spins and magnets,"The possible use of spin and magnets in place of charge and capacitors to
+store and process information is well known. Magnetic tunnel junctions are
+being widely investigated and developed for magnetic random access memories.
+These are two terminal devices that change their resistance based on switchable
+magnetization of magnetic materials. They utilize the interaction between
+electron spin and magnets to read information from the magnets and write onto
+them. Such advances in memory devices could also translate into a new class of
+logic devices that offer the advantage of nonvolatile and reconfigurable
+information processing over transistors. Logic devices having a transistor-like
+gain and directionality could be used to build integrated circuits without the
+need for transistor-based amplifiers and clocks at every stage. We review
+device characteristics and basic logic gates that compute with spins and
+magnets from the mesoscopic to the atomic scale, as well as materials,
+integration, and fabrication challenges and methods.",1411.6960v1
+2015-02-27,RC-circuit-like dynamic characteristic of the magnetic domain wall in ferromagnetic nanowires,"We have investigated dynamic behaviors of the magnetic domain wall under
+perpendicular magnetic field pulses in ferromagnetic nanowires using
+micromagnetic simulations. It has been found that the perpendicular magnetic
+field pulse can trigger the magnetic domain wall motion, where all the field
+torques are kept to be on the plane of nanowire strip. The magnetic domain wall
+speed faster than several hundreds meters per second is predicted without the
+Walker breakdown for the perpendicular magnetic driving field stronger than
+$200~\mathrm{mT}$. Interestingly, the dynamic behavior of the moving magnetic
+domain wall driven by perpendicular magnetic field pulses is explained by
+charging- and discharging-like behaviors of an electrical RC-circuit model,
+where the charging and the discharging of ""magnetic charges"" on the nanowire
+planes are considered. The concept of the RC-model-like dynamic characteristic
+of the magnetic domain wall might be promising for spintronic functional device
+applications based on the magnetic domain wall motion.",1502.07807v1
+2015-03-30,Effects of non-radial magnetic field on measuring magnetic helicity transport across solar photosphere,"It is generally believed that the evolution of magnetic helicity has a close
+relationship with solar activity. Before the launch of SDO, earlier studies
+have mostly used MDI/SOHO line of sight magnetograms and assumed that magnetic
+fields are radial when calculating magnetic helicity injection rate from
+photospheric magnetograms. However, this assumption is not necessarily true.
+Here we use the vector magnetograms and line of sight magnetograms, both taken
+by HMI/SDO, to estimate the effects of non-radial magnetic field on measuring
+magnetic helicity injection rate. We find that: 1) The effect of non-radial
+magnetic field on estimating tangential velocity is relatively small; 2) On
+estimating magnetic helicity injection rate, the effect of non-radial magnetic
+field is strong when active regions are observed near the limb and is
+relatively small when active regions are close to disk center; 3) The effect of
+non-radial magnetic field becomes minor if the amount of accumulated magnetic
+helicity is the only concern.",1503.08563v1
+2015-08-18,A self-consistent study of magnetic field effects on hybrid stars,"In this work we study the effects of strong magnetic fields on hybrid stars
+by using a full general-relativity approach, solving the coupled
+Maxwell-Einstein equation in a self-consistent way. The magnetic field is
+assumed to be axi-symmetric and poloidal. We take into consideration the
+anisotropy of the energy-momentum tensor due to the magnetic field, magnetic
+field effects on equation of state, the interaction between matter and the
+magnetic field (magnetization), and the anomalous magnetic moment of the
+hadrons. The equation of state used is an extended hadronic and quark SU(3)
+non-linear realization of the sigma model that describes magnetized hybrid
+stars containing nucleons, hyperons and quarks. According to our results, the
+effects of the magnetization and the magnetic field on the EoS do not play an
+important role on global properties of these stars. On the other hand, the
+magnetic field causes the central density in these objects to be reduced,
+inducing major changes in the populated degrees of freedom and, potentially,
+converting a hybrid star into a hadronic star.",1508.04431v1
+2015-09-05,Magnetic and magnetocaloric properties of quasi-one-dimensional Ising spin chain CoV$_{2}$O$_{6}$,"We have investigated the magnetic and magnetocaloric properties of
+antiferromagnetic Ising spin chain CoV$_{2}$O$_{6}$ by magnetization and heat
+capacity measurements. Both monoclinic $\alpha$-CoV$_{2}$O$_{6}$ and triclinic
+$\gamma$-CoV$_{2}$O$_{6}$ exhibit field-induced metamagnetic transition from
+antiferromagnetic to ferromagnetic state via an intermediate ferrimagnetic
+state with 1/3 magnetization plateau. Due to this field-induced metamagnetic
+transition, these systems show large conventional as well as inverse
+magnetocaloric effects. In $\alpha$-CoV$_{2}$O$_{6}$, we observe field-induced
+complex magnetic phases and multiple magnetization plateaux at low temperature
+when the field is applied along $c$ axis. Several critical temperatures and
+fields have been identified from the temperature and field dependence of
+magnetization, magnetic entropy change and heat capacity to construct the
+$H$-$T$ phase diagram. As compared to $\alpha$-CoV$_{2}$O$_{6}$,
+$\gamma$-CoV$_{2}$O$_{6}$ displays a relatively simple magnetic phase diagram.
+Due to the large magnetic entropy change and adiabatic temperature change at
+low or moderate applied magnetic field, $\gamma$-CoV$_{2}$O$_{6}$ may be
+considered as a magnetic refrigerant in the low-temperature region.",1509.01690v2
+2015-11-16,Observation of Magnetic Superviscosity in Metglas 2605SA1,"A quasi time constant for magnetic domain relaxation of Metglas 20605SA1 has
+been measured to be 2.6 hours. The effective relative magnetic permeability has
+been measured to be 57,000 after relaxation.",1511.05127v1
+2017-02-28,Chemical Responsive Single Crystal Organic Magnet,"Materials that change their magnetic properties in response to the external
+stimuli have long been of interest for their potential applicability in
+magnetic storage device, spintronics and smart magnetic materials. Organic
+materials are suitable candidates for such materials due to their chemical
+diversity, flexibility and designablity. However, most methods used for
+changing magnetism are inefficient or destructive to the magnetic material.
+Hence there is a need for innovation in this field. Here we report
+high-performance magnetic control of a gas-responsive single-molecule magnet
+(SMM). The results exhibit that the magnetic properties of the SMM can be
+significantly changed according to the gas environment it is in and some of the
+magnetic states can be reversibly transformed or coexistent in the SMM through
+artificial control. More importantly, the monocrystalline structure of the SMM
+remains unchanged during the transformation process except for slight change of
+the lattice constant. Thus, this work opens up new insights into the
+stimuli-responsive magnetic materials which have great prospects for
+application in artificial design magnetic network and also highlight their
+potential as smart materials.",1703.00006v2
+2018-02-14,Axisymmetric magnetic modes of neutron stars having mixed poloidal and toroidal magnetic fields,"We calculate axisymmetric magnetic modes of a neutron star possessing a mixed
+poloidal and toroidal magnetic field, where the toroidal field is assumed to be
+proportional to a dimensionless parameter $\zeta_0$. Here, we assume an
+isentropic structure for the neutron star and consider no effects of rotation.
+Ignoring the equilibrium deformation due to the magnetic field, we employ a
+polytrope of the index $n=1$ as the background model for our modal analyses.
+For the mixed poloidal and toroidal magnetic field with $\zeta_0\not=0$,
+axisymmetric spheroidal and toroidal modes are coupled. We compute axisymmetric
+spheroidal and toroidal magnetic modes as a function of the parameter $\zeta_0$
+from $0$ to $\sim 1$ for the surface field strengths $B_S=10^{14}$G and
+$10^{15}$G. We find that the frequency $\omega$ of the magnetic modes decreases
+with increasing $\zeta_0$. We also find that the frequency of the spheroidal
+magnetic modes is almost exactly proportional to $B_S$ for $\zeta_0\lesssim 1$
+but that this proportionality holds only when $\zeta_0\ll 1$ for the toroidal
+magnetic modes. The wave patterns of the spheroidal magnetic modes and toroidal
+magnetic modes are not strongly affected by the coupling so long as
+$\zeta_0\lesssim 1$. We find no unstable modes having $\omega^2<0$.",1802.04957v1
+2017-01-12,Interplay of iron and rare-earth magnetic order in rare-earth iron pnictide superconductors under magnetic field,"The magnetic properties of iron pnictide superconductors with magnetic
+rare-earth ions under strong magnetic field are investigated based on the
+cluster self-consistent field method. Starting from an effective Heisenberg
+model, we present the evolution of magnetic structures on magnetic field in
+RFeAsO (R=Ce, Pr, Nd, Sm, Gd and Tb) and RFe2As2 (R=Eu) compounds. It is found
+that spin-flop transition occurs in both rare-earth and iron layers under
+magnetic field, in good agreement with the experimental results. The interplay
+between rare-earth and iron spins plays a key role in the magnetic-field-driven
+magnetic phase transition, which suggests that the rare-earth layers can
+modulate the magnetic behaviors of iron layers. In addition, the factors that
+affect the critical magnetic field for spin-flop transition are also discussed.",1701.03258v1
+2017-01-19,Linear Stability Analysis of a Levitated Nanomagnet in a Static Magnetic Field: Quantum Spin Stabilized Magnetic Levitation,"We theoretically study the levitation of a single magnetic domain nanosphere
+in an external static magnetic field. We show that apart from the stability
+provided by the mechanical rotation of the nanomagnet (as in the classical
+Levitron), the quantum spin origin of its magnetization provides two additional
+mechanisms to stably levitate the system. Despite of the Earnshaw theorem, such
+stable phases are present even in the absence of mechanical rotation. For large
+magnetic fields, the Larmor precession of the quantum magnetic moment
+stabilizes the system in full analogy with magnetic trapping of a neutral atom.
+For low magnetic fields, the magnetic anisotropy stabilizes the system via the
+Einstein-de Haas effect. These results are obtained with a linear stability
+analysis of a single magnetic domain rigid nanosphere with uniaxial anisotropy
+in a Ioffe-Pritchard magnetic field.",1701.05410v3
+2018-05-07,Single-shot multi-level all-optical magnetization switching mediated by spin-polarized hot electron transport,"All-optical ultrafast magnetization switching in magnetic material thin film
+without the assistance of an applied external magnetic field is being explored
+for future ultrafast and energy-efficient magnetic storage and memories. It has
+been shown that femto-second light pulses induce magnetization reversal in a
+large variety of magnetic materials. However, so far, only GdFeCo-based
+ferrimagnetic thin films exhibit magnetization switching via a single optical
+pulse. Here we demonstrate the single-pulse switching of Co/Pt multilayers
+within a magnetic spin-valve structure ([Co/Pt] / Cu / GdFeCo) and further show
+that the four possible magnetic configurations of the spin valve can be
+accessed using a sequence of single femto-second light pulses. Our experimental
+study reveals that the magnetization final state of the ferromagnetic [Co/Pt]
+layer is determined by spin-polarized hot electrons generated by the light
+pulse interactions with the GdFeCo layer. This work provides a new approach to
+deterministically switch ferromagnetic layers and a pathway to engineering
+materials for opto-magnetic multi-bit recording.",1805.02432v1
+2012-04-26,Axisymmetric and stationary structures of magnetized barotropic stars with extremely strong magnetic fields deep inside,"We have succeeded in obtaining magnetized star models that have extremely
+strong magnetic fields in the interior of the star. In our formulation,
+arbitrary functions of the magnetic flux function appear in the expression for
+the current density. By appropriately choosing the functional form for one of
+the arbitrary functions that corresponds to the distribution of the toroidal
+current density, we have obtained configurations with magnetic field
+distributions that are highly localized within the central part and near the
+magnetic axis region. The absolute values of the central magnetic fields are
+stronger than those of the surface region by two orders of magnitude. By
+applying our results to magnetars, the internal magnetic poloidal fields could
+be 10^17 G, although the surface magnetic fields are about 10^15 G in the case
+of magnetars. For white dwarfs, the internal magnetic poloidal fields could be
+10^12 G, when the surface magnetic fields are 10^9-10^10 G .",1204.5830v2
+2018-09-19,Effect of external magnetic field on nucleon mass in hot and dense medium : Inverse Magnetic Catalysis in Walecka Model,"Vacuum to nuclear matter phase transition has been studied in presence of
+constant external background magnetic field with the mean field approximation
+in Walecka model. The anomalous nucleon magnetic moment has been taken into
+account using the modified ""weak"" field expansion of the fermion propagator
+having non-trivial correction terms for charged as well as for neutral
+particles. The effect of nucleon magnetic moment is found to favour the
+magnetic catalysis effect at zero temperature and zero baryon density. However,
+extending the study to finite temperatures, it is observed that the anomalous
+nuclear magnetic moment plays a crucial role in characterizing the qualitative
+behaviour of vacuum to nuclear matter phase transition even in case of the weak
+external magnetic fields . The critical temperature corresponding to the vacuum
+to nuclear medium phase transition is observed to decrease with the external
+magnetic field which can be identified as the inverse magnetic catalysis in
+Walecka model whereas the opposite behaviour is obtained in case of vanishing
+magnetic moment indicating magnetic catalysis.",1809.07028v1
+2019-10-17,Magnetic textures and dynamics in magnetic Weyl semimetals,"Recent theoretical and experimental attemps have been successful in finding
+magnetic Weyl semimetal phases, which show both nodal-point structure in the
+electronic bands and magnetic orders. Beyond uniform ferromagnetic or
+antiferromagnetic orders, nonuniform magnetic textures, such as domain walls
+and skyrmions, may even more enrich the properties of the Weyl electrons in
+such materials. This article gives a topical review on interplay between Weyl
+electrons and magnetic textures in those magnetic Weyl semimetals. The basics
+of magnetic textures in non-topological magnetic metals are reviewed first, and
+then the effect of magnetic textures in Weyl semimetals is discussed, regarding
+the recent theoretical and experimental progress therein. The idea of the
+fictitious ""axial gauge fields"" is pointed out, which effectively describes the
+effect of magnetic textures on the Weyl electrons and can well account for the
+properties of the electrons localized around magnetic domain walls.",1910.07774v1
+2020-04-25,Pulse-assisted magnetization switching in magnetic nanowires at picosecond and nanosecond timescales with low energy,"Detailed understanding of spin dynamics in magnetic nanomaterials is
+necessary for developing ultrafast, low-energy and high-density spintronic
+logic and memory. Here, we develop micromagnetic models and analytical
+solutions to elucidate the effect of increasing damping and uniaxial anisotropy
+on magnetic field pulse-assisted switching time, energy and field requirements
+of nanowires with perpendicular magnetic anisotropy and yttrium iron
+garnet-like spin transport properties. A nanowire is initially magnetized using
+an external magnetic field pulse (write) and self-relaxation. Next, magnetic
+moments exhibit deterministic switching upon receiving 2.5 ns-long external
+magnetic pulses in both vertical polarities. Favorable damping
+({\alpha}~0.1-0.5) and anisotropy energies (10^4-10^5 J m^-3) allow for as low
+as picosecond magnetization switching times. Magnetization reversal with fields
+below coercivity was observed using spin precession instabilities. A
+competition or a nanomagnetic trilemma arises among the switching rate, energy
+cost and external field required. Developing magnetic nanowires with optimized
+damping and effective anisotropy could reduce the switching energy barrier down
+to 3163kBT at room temperature. Thus, pulse-assisted picosecond and low energy
+switching in nanomagnets could enable ultrafast nanomagnetic logic and cellular
+automata.",2004.12243v1
+2020-12-09,Optimization of a NdFeB permanent magnet configuration for in-vivo drug delivery experiments,"We propose a new concept of magnetic focusing for targeting and accumulation
+of functionalized superparamagnetic nanoparticles in living organs through
+composite configurations of different permanent magnets. The proposed setups
+fulfill two fundamental requirements for in vivo experiments: 1) reduced size
+of the magnets to best focusing on small areas representing the targeted organs
+of mice and rats and 2) maximization of the magnetic driving force acting on
+the magnetic nanoparticles dispersed in blood. To this aim, several
+configurations of permanent magnets organized with different degrees of
+symmetry have been tested. The product B*grad(B) proportional to the magnetic
+force has been experimentally measured, over a wide area (20x20 mm^2), at a
+distance corresponding to the hypothetical distance of the mouse organ from the
+magnets. A non-symmetric configuration of mixed shape permanent magnets
+resulted in particularly promising to achieve the best performances for further
+in vivo experiments.",2012.05059v1
+2021-01-15,Magnetized Rutherford scattering angle for electron-ion collision in plasma,"Rutherford scattering formula plays an important role in plasma classical
+transport. It is urgent to need a magnetized Rutherford scattering formula
+since the magnetic field increases significantly in different fusion areas
+(e.g. tokamak magnetic field, self-generated magnetic field, and compressed
+magnetic field). The electron-ion Coulomb collisions perpendicular to the
+external magnetic field are studied in this paper. The scattering angle is
+defined according to the electron trajectory and asymptotic line (without
+magnetic field). A magnetized Rutherford scattering formula is obtained
+analytically under the weak magnetic field approximation. It is found that the
+scattering angle decreases as external magnetic field increases. It is easy to
+find the scattering angle decreasing significantly as incident distance, and
+incident velocity increasing. It is shown that the theoretical results agree
+well with numerical calculation by checking the dependence of scattering angle
+on external magnetic field.",2101.05943v1
+2017-09-13,Contactless and absolute linear displacement detection based upon 3D printed magnets combined with passive radio-frequency identification,"Within this work a passive and wireless magnetic sensor, to monitor linear
+displacements is proposed. We exploit recent advances in 3D printing and
+fabricate a polymer bonded magnet with a spatially linear magnetic field
+component corresponding to the length of the magnet. Regulating the magnetic
+compound fraction during printing allows specific shaping of the magnetic field
+distribution. A giant magnetoresistance magnetic field sensor is combined with
+a radio-frequency identification tag in order to passively monitor the exerted
+magnetic field of the printed magnet. Due to the tailored magnetic field, a
+displacement of the magnet with respect to the sensor can be detected within
+the sub-mm regime. The sensor design provides good flexibility by controlling
+the 3D printing process according to application needs. Absolute displacement
+detection using low cost components and providing passive operation, long term
+stability and longevity renders the proposed sensor system ideal for structural
+health monitoring applications.",1709.04220v1
+2018-12-13,Measuring Earth's Magnetic Field Using a Smartphone Magnetometer,"I use the magnetometers of a smartphone to measure the magnitude of the
+earth's magnetic field. A method for eliminating bias due to internal magnetic
+fields in the phone is proposed.",1901.00857v1
+2019-12-03,Magnetic Force Microscopy Revealing Molecule Impact on Magnetic Tunnel Junction Based Molecular Devices at Room Temperature,"Commercially successful magnetic tunnel junction can harness the unmatched
+capabilities of molecular device elements by solving decade-old fabrication
+issues. Utilization of magnetic tunnel junction as a testbed for molecules also
+enables unprecedented magnetic studies of molecular spintronics devices. This
+paper utilizes magnetic force microscopy (MFM) to vividly show that
+organometallic molecules when bridged between two ferromagnetic electrodes
+along the magnetic tunnel junction edges, transformed the magnetic electrodes
+itself. Molecules impacted several hundred-micron areas of ferromagnetic
+electrodes at room temperature. Complementary, magnetic resonance and
+magnetometer studies supported the dramatic MFM results. Molecule induced
+changes in the magnetic electrodes impacted the transport of the magnetic
+tunnel junction and stabilized as much as six orders smaller current at room
+temperature. Magnetic tunnel junction based molecular devices can be a gateway
+to a vast range of commercially viable futuristic logic and memory devices that
+are controlled by the molecular quantum states near room temperature.",1912.01316v1
+2019-12-12,Potential analysis of holographic Schwinger effect in the magnetized background,"We study the holographic Schwinger effect with magnetic field at RHIC and LHC
+energies by using the AdS/CFT correspondence. We consider both weak and strong
+magnetic field cases with $B\ll T^2$ and $B\gg T^2$ solutions respectively.
+Firstly, we calculate separating length of the particle pairs at finite
+magnetic field. It is found that for both weak and strong magnetic field
+solutions the maximum value of separating length decreases with the increase of
+magnetic field , which can be inferred that the virtual electron-positron pairs
+become real particles more easily. We also find that the magnetic field reduces
+the potential barrier and the critical field for the weak magnetic field
+solution, thus favors the Schwinger effect. With strong magnetic field
+solution, the magnetic field enhances the Schwinger effect when the pairs are
+in perpendicular to the magnetic field although the magnetic field increases
+the critical electric field.",1912.05806v2
+2019-12-24,The origin and effect of hemispheric helicity imbalance in solar dynamo,"In this paper we study the effects of hemispheric imbalance of magnetic
+helicity density on breaking the equatorial reflection symmetry of the dynamo
+generated large-scale magnetic field. Our study employs the axisymmetric dynamo
+model which takes into account the nonlinear effect of magnetic helicity
+conservation. We find that the evolution of the net magnetic helicity density,
+in other words, the magnetic helicity imbalance, on the surface follows the
+evolution of the parity of the large-scale magnetic field. Random fluctuations
+of the $\alpha$-effect and the helicity fluxes can inverse the causal
+relationship, i.e., the magnetic helicity imbalance or the imbalance of
+magnetic helicity fluxes can drive the magnetic parity breaking. We also found
+that evolution of the net magnetic helicity of the small-scale fields follows
+the evolution of the net magnetic helicity of the large-scale fields with some
+time lag. We interpret this as an effect of the difference of the magnetic
+helicity fluxes out of the Sun from the large and small scales.",1912.11285v2
+2020-03-09,Magnetic Noise Enabled Biocompass,"The discovery of magnetic protein provides a new understanding of a
+biocompass at the molecular level. However, the mechanism by which magnetic
+protein enables a biocompass is still under debate, mainly because of the
+absence of permanent magnetism in the magnetic protein at room temperature.
+Here, based on a widely accepted radical pair model of a biocompass, we propose
+a microscopic mechanism that allows the biocompass to operate without a finite
+magnetization of the magnetic protein in a biological environment. With the
+structure of the magnetic protein, we show that the magnetic fluctuation,
+rather than the permanent magnetism, of the magnetic protein can enable
+geomagnetic field sensing. An analysis of the quantum dynamics of our
+microscopic model reveals the necessary conditions for optimal sensitivity. Our
+work clarifies the mechanism by which magnetic protein enables a biocompass.",2003.13816v2
+2020-05-02,Optically driven ultrafast magnetic order transitions in two-dimensional ferrimagnets,"Laser-induced switching and manipulation of the spins in magnetic materials
+are of great interest to revolutionize future magnetic storage technology and
+spintronics with fastest speed and least power dissipative. Inspired by the
+recent discovery of intrinsic two-dimensional (2D) magnets, which provide
+unique platform to explore the new phenomenon for light-control magnetism in
+the 2D limit, we propose to realize light can efficiently tune magnetic
+properties of 2D ferrimagnets in early time. Here, using the 2D ferrimagnetic
+MXenes as prototype systems, our real-time density functional theory (TDDFT)
+simulation show that laser pulses can directly induce ultrafast spin-selective
+charge transfer between two magnetic sublattices on a few femtoseconds, and
+further generate dramatic changes in the magnetic structure of these MXenes,
+including a magnetic order transition from ferrimagnetic (FiM) to transient
+ferromagnetic (FM). The microscopic mechanism underpinning this ultrafast
+switching of magnetic order in MXenes is governed by optically induced
+inter-site spin transfer (OISTR) effect, which theoretically enables the
+ultrafast direct optical manipulation of the magnetic state in MXenes-based
+materials. Our results open new opportunities to optically manipulate the spin
+in 2D magnets.",2005.00871v1
+2020-06-03,Structural and magnetic properties of small symmetrical and asymmetrical sized fullerene dimers,"Magnetism in carbon nanostructures is of high scientific interest, which
+could lead to novel magnetic materials. The magnetic properties of symmetrical
+and asymmetrical sized small fullerene dimers have been investigated using spin
+polarized density functional theory. The interaction energies depict that small
+fullerene cages form stable dimer structures and symmetrical sized fullerene
+dimers are found more stable than asymmetrical sized dimers. The dimerization
+of fullerene cages in different modes leads to change in their magnetic
+properties. The non-magnetic fullerene cages become magnetic after formation of
+dimer (C20-C20, C24-C24, C32-C32, C40-C40, C20-C24, C40-C44 and
+C44-C50),whereas the magnetism of magnetic fullerenes is enhanced or lowered
+after dimerization (C28-C28 C36-C36, C24-C28, C28-C32, C32-C36 and C36-C40).
+The individual cages of dimer structures show ferromagnetic interactions
+amongst them and resultant magnetic moment strongly depends on the type of
+inter-connecting bonds. The magnetism may also be explained based on distortion
+of carbon cages and change in the density of states (DOS) in dimer
+configuration. The calculations presented show strong possibility of
+experimental synthesis of small fullerene based magnetic dimers.",2006.02233v1
+2020-09-03,Coincidence inelastic neutron scattering for detection of two-spin magnetic correlations,"Inelastic neutron scattering (INS) is one powerful technique to study the
+low-energy single-spin dynamics of magnetic materials. A variety of quantum
+magnets show novel magnetic correlations such as quantum spin liquids. These
+novel magnetic correlations are beyond the direct detection of INS. In this
+paper we propose a coincidence technique, coincidence inelastic neutron
+scattering (cINS), which can detect the two-spin magnetic correlations of the
+magnetic materials. In cINS there are two neutron sources and two neutron
+detectors with an additional coincidence detector. Two neutrons from the two
+neutron sources are incident on the target magnetic material, and they are
+scattered by the electron spins of the magnetic material. The two scattered
+neutrons are detected by the two neutron detectors in coincidence with the
+coincidence probability described by a two-spin Bethe-Salpeter wave function.
+Since the two-spin Bethe-Salpeter wave function defines the momentum-resolved
+dynamical wave function with two spins excited, cINS can explicitly detect the
+two-spin magnetic correlations of the magnetic material. Thus, it can be
+introduced to study the various spin valence bond states of the quantum
+magnets.",2009.01680v2
+2020-10-19,Magnetic texture based magnonics,"The spontaneous magnetic orders arising in ferro-, ferri- and
+antiferromagnets stem from various magnetic interactions. Depending on the
+interplay and competition among the Heisenberg exchange interaction,
+Dzyaloshinskii-Moriya exchange interaction, magnetic dipolar interaction and
+crystal anisotropies, a great variety of magnetic textures may be stabilized,
+such as magnetic domain walls, vortices, Skyrmions and spiral helical
+structures. While each of these spin textures responds to external forces in a
+specific manner with characteristic resonance frequencies, they also interact
+with magnons, the fundamental collective excitation of the magnetic order,
+which can propagate in magnetic materials free of charge transport and
+therefore with low energy dissipation. Recent theories and experiments found
+that the interplay between spin waves and magnetic textures is particularly
+interesting and rich in physics. In this review, we introduce and discuss the
+theoretical framework of magnons living on a magnetic texture background, as
+well as recent experimental progress in the manipulation of magnons via
+magnetic textures. The flexibility and reconfigurability of magnetic textures
+are discussed regarding the potential for applications in information
+processing schemes based on magnons.",2010.09180v1
+2021-04-02,Highly Complex Magnetic Structures Resulting From Hierarchical Phase Separation in AlCo(Cr)FeNi High Entropy Alloys,"Magnetic high entropy alloys (HEAs) are a new category of high-performance
+magnetic materials, with multi-component concentrated compositions and complex
+multi-phase structures. Although there have been numerous reports of their
+interesting magnetic properties, there is very limited understanding about the
+interplay between their hierarchical multi-phase structures and their local
+magnetic structures. By employing high spatial resolution correlative magnetic,
+structural and chemical studies, we reveal the influence of a hierarchically
+decomposed B2 + A2 structure in an AlCo0.5Cr0.5FeNi HEA on the formation of
+magnetic vortex states within individual A2 (disordered BCC) precipitates,
+which are distributed in an ordered B2 matrix that is weakly ferromagnetic.
+Non-magnetic or weakly ferromagnetic B2 precipitates in large magnetic domains
+of the A2 phase, and strongly magnetic Fe-Co-rich interphase A2 regions, are
+also observed. These results provide important insight into the origin of
+coercivity in this HEA, which can be attributed to a complex magnetization
+process that includes the successive reversal of magnetic vortices.",2104.00943v1
+2021-06-28,Stability of a Magnetically Levitated Nanomagnet in Vacuum: Effects of Gas and Magnetization Damping,"In the absence of dissipation a non-rotating magnetic nanoparticle can be
+stably levitated in a static magnetic field as a consequence of the spin origin
+of its magnetization. Here we study the effects of dissipation on the stability
+of the system, considering the interaction with the background gas and the
+intrinsic Gilbert damping of magnetization dynamics. At large applied magnetic
+fields we identify magnetization switching induced by Gilbert damping as the
+key limiting factor for stable levitation. At low applied magnetic fields and
+for small particle dimensions magnetization switching is prevented due to the
+strong coupling of rotation and magnetization dynamics, and the stability is
+mainly limited by the gas-induced dissipation. In the latter case, high vacuum
+should be sufficient to extend stable levitation over experimentally relevant
+timescales. Our results demonstrate the possibility to experimentally observe
+the phenomenon of quantum spin stabilized magnetic levitation.",2106.14858v3
+2021-08-26,Magnetic design study of coil-dominated superconducting quadrupole magnets based on racetrack coils,"Several coil structures have been used in accelerator superconducting
+quadrupole magnets, and cos2{\theta} quadrupole magnets are the most mature in
+theoretical research and engineering applications. However, the cos2{\theta}
+quadrupole magnet has a complicated coil structure, especially at the end of
+the coil, which makes it difficult to apply strain-sensitive high-temperature
+superconductors. Racetrack quadrupole magnets are friendly to high-temperature
+superconductors. Field strength of iron-dominated racetrack magnets is limited
+by the magnetic saturation of the iron poles. Therefore, coil-dominated
+racetrack quadrupole magnets with simple geometry have become the focus of our
+research. In this paper, analytical expressions of the magnetic field harmonics
+related to racetrack quadrupole coil parameters are obtained. These expressions
+are used to find the solution of coil geometry parameters with field harmonics
+on the order of 10-4. Then, examples are given to build ideal quadrupole model
+and verify the theoretical formulas. Next, the design and optimization of
+example racetrack quadrupole magnets are completed in ROXIE. Finally, the
+advantages and disadvantages of the racetrack coils and the cos2{\theta} coils
+are compared and discussed.",2108.11643v1
+2021-12-21,Tunable room temperature magnetic skyrmions in centrosymmetric kagome magnet Mn$_4$Ga$_2$Sn,"The successful realization of skyrmion-based spintronic devices depends on
+the easy manipulation of underlying magnetic interactions in the
+skyrmion-hosting materials. Although the mechanism of skyrmion formation in
+non-centrosymmetric magnets is comprehensively established, the stabilization
+process of different skyrmion-like magnetic textures in centrosymmetric magnets
+needs further investigation. Here, we utilize Lorentz transmission electron
+microscopy study to report the finding of a tunable skyrmion lattice up to room
+temperature in a centrosymmetric kagome ferromagnet Mn$_4$Ga$_2$Sn. We
+demonstrate that a controlled switching between the topological skyrmions and
+non-topological type-II magnetic bubbles can be realized at the optimal
+magnetic anisotropy. We find that the topological skyrmions are the
+energetically most stable magnetic objects in the centrosymmetric hexagonal
+magnets, whereas application of in-plane magnetic field stabilizes type-II
+magnetic bubbles as an excited state. The present study is a significant step
+towards understanding of the skyrmion stabilization mechanism in
+centrosymmetric materials for their future applications.",2112.11259v2
+2022-02-25,Magnetic-Field-Dependent Thermodynamic Properties of Square and Quadrupolar Artificial Spin Ice,"Applied magnetic fields are an important tuning parameter for artificial spin
+ice (ASI) systems, as they can drive phase transitions between different
+magnetic ground states, or tune through regimes with high populations of
+emergent magnetic excitations (e.g., monopole-like quasiparticles). Here, using
+simulations supported by experiments, we investigate the thermodynamic
+properties and magnetic phases of square and quadrupolar ASI as a function of
+applied in-plane magnetic fields. Monte Carlo simulations are used to generate
+field-dependent maps of the magnetization, the magnetic specific heat, the
+thermodynamic magnetization fluctuations, and the magnetic order parameters,
+all under equilibrium conditions. These maps reveal the diversity of magnetic
+orderings and the phase transitions that occur in different regions of the
+phase diagrams of these ASIs, and are experimentally supported by
+magneto-optical measurements of the equilibrium ""magnetization noise"" in
+thermally-active ASIs.",2202.12486v1
+2022-03-23,R&D works for Superconducting Magnet for Future Accelerator Applications in Japan,"KEK cryogenics science center is developing superconducting magnet technology
+for future accelerator science. Three major technological categories are
+focused; 1) high precision 3D magnetic field technology based on the g-2/EDM
+magnet developments, 2) rad-hard superconducting magnet technology based on the
+COMET magnet developments, and 3) high magnetic field superconducting magnet
+technology for future colliders based on the LHC MQXA and HL-LHC D1 magnet
+developments. Extensive studies including Nb3Sn conductor and magnet
+developments for high field magnets and HTS for rad-hard superconducting
+magnets are ongoing with various collaboration programs such as the US-Japan
+research collaboration.",2203.12118v1
+2022-04-26,Slow spin dynamics and quantum tunneling of magnetization in the dipolar antiferromagnet DyScO$_3$,"We present a comprehensive study of static and dynamic magnetic properties in
+the Ising-like dipolar antiferromagnet (AFM) DyScO$_3$\ by means of DC and AC
+magnetization measurements supported by classical Monte-Carlo calculations. Our
+AC-susceptibility data show that the magnetic dynamics exhibit a clear
+crossover from an Arrhenius-like regime to quantum tunneling of magnetization
+(QTM) at $T^* = 10$ K. Below $T_{\mathrm{N}} = 3.2$ K DyScO$_3$ orders in an
+antiferromagnetic $GxAy$-type magnetic structure and the magnetization dynamics
+slow down to the minute timescale. The low-temperature magnetization curves
+exhibit complex hysteretic behavior, which depends strongly on the magnetic
+field sweep rate. We demonstrate that the low-field anomalies on the
+magnetization curve are related to the metamagnetic transition, while the
+hysteresis at higher fields is induced by a strong magnetocaloric effect. Our
+theoretical calculations, which take into account dipolar interaction between
+Dy$^{3+}$ moments, reproduce essential features of the magnetic behavior of
+DyScO$_3$. We demonstrate that DyScO$_3$ represents a rare example of inorganic
+compound, which exhibits QTM at a single-ion level and magnetic order due to
+classical dipolar interaction.",2204.12398v1
+2022-05-08,Two-dimensional characterization of three-dimensional magnetic bubbles in Fe$_3$Sn$_2$ nanostructures,"We report differential phase contrast scanning transmission electron
+microscopy (TEM) of nanoscale magnetic objects in Kagome ferromagnet
+Fe$_3$Sn$_2$ nanostructures. This technique can directly detect the deflection
+angle of a focused electron beam, thus allowing clear identification of the
+real magnetic structures of two magnetic objects including three-ring and
+complex arch-shaped vortices in Fe$_3$Sn$_2$ by Lorentz transmission electron
+microscopy imaging. Numerical calculations based on real material-specific
+parameters well reproduced the experimental results, showing that the magnetic
+objects can be attributed to integral magnetizations of two types of complex
+three-dimensional (3D) magnetic skyrmion bubbles with depth-modulated spin
+twisting. Magnetic configurations obtained using the high-resolution TEM are
+generally considered as two-dimensional (2D) magnetic objects previously. Our
+results imply the importance of the integral magnetizations of underestimated
+3D magnetic structures in 2D TEM magnetic characterizations.",2205.03751v2
+2022-05-09,"Controlling magnetic exchange and anisotropy by non-magnetic ligand substitution in layered MPX3 (M = Ni, Mn; X = S, Se)","Recent discoveries in two-dimensional (2D) magnetism have intensified the
+investigation of van der Waals (vdW) magnetic materials and further improved
+our ability to tune their magnetic properties. Tunable magnetism has been
+widely studied in antiferromagnetic metal thiophosphates MPX3. Substitution of
+metal ions M has been adopted as an important technique to engineer the
+magnetism in MPX3. In this work, we have studied the previously unexplored
+chalcogen X substitutions in MPX3 (M = Mn/Ni; X = S/Se). We synthesized the
+single crystals of MnPS3-xSex (0 < x < 3) and NiPS3-xSex (0 < x < 1.3) and
+investigated the systematic evolution of the magnetism with varying x. Our
+study reveals the effective tuning of magnetic interactions and anisotropies in
+both MnPS3 and NiPS3 upon Se substitution. Such efficient engineering of the
+magnetism provides a suitable platform to understand the low-dimensional
+magnetism and develop future magnetic devices.",2205.04585v1
+2022-05-28,Finite element simulation for validation of multi-dipole line cusp magnetic field configuration for MPD,"A Multi-dipole line cusp configured Plasma Device (MPD) having six
+electromagnets with embedded Vacoflux-50 as a core material has been operated
+with a capability to experimentally control the field-free region, the radial
+profile of magnetic field, and pole magnetic field by changing magnet current.
+For the validation of multi-dipole line cusp magnetic field (MMF) configuration
+in a 3-D geometry, a finite element simulation has been performed using COMSOL
+software. This paper presents 3-D magnetic field simulation results of
+multi-pole line cusp magnetic field configuration performed over the 1.2m
+length and 40cm diameter chamber in the vacuum condition. The simulation
+results show good agreement with the experimentally measured magnetic field
+profile. The performed magnetic field simulation results clearly capture that
+this configuration has full control over a null region (nearly field-free
+region) as well is capable to change the magnetic field values and radial
+variation of the magnetic field. Moreover, the magnetic field profiles over the
+end cross-section of the device have been discussed.",2205.14381v1
+2022-05-20,A Sacrificial Magnet Concept for Field Dependent Surface Science Studies,"We demonstrate a straightforward approach to integrating a magnetic field
+into a low-temperature scanning tunneling microscope (STM) by adhering an NdFeB
+permanent magnet to a magnetizable sample plate. To render our magnet concept
+compatible with high-temperature sample cleaning procedures, we make the
+irreversible demagnetization of the magnet a central part of our preparation
+cycle. After sacrificing the magnet by heating it above its Curie temperature,
+we use a transfer tool to attach a new magnet in-situ prior to transferring the
+sample into the STM. We characterize the magnetic field created by the magnet
+using the Abrikosov vortex lattice of superconducting NbSe2. Excellent
+agreement between the distance dependent magnetic fields from experiments and
+simulations allows us to predict the magnitude and orientation of magnetic flux
+at any location with respect to the magnet and the sample plate. Our concept is
+an accessible solution for field-dependent surface science studies that require
+fields in the range of up to 400 mT and otherwise detrimental heating
+procedures.",2206.02529v1
+2022-07-14,Formation of Quiescent Prominence Magnetic Field by Supergranulations,"To understand the formation of quiescent solar prominences, the origin of
+their magnetic field structures, i.e., magnetic flux ropes (MFRs), must be
+revealed. We use three-dimensional magnetofriction simulations in a spherical
+subdomain to investigate the role of typical supergranular motions in the
+long-term formation of a prominence magnetic field. Time-dependant horizontal
+supergranular motions with and without the effect of Coriolis force are
+simulated on the solar surface via Voronoi tessellation. The vortical motions
+by the Coriolis effect at boundaries of supergranules inject magnetic helicity
+into the corona. The helicity is transferred and accumulated along the polarity
+inversion line (PIL) as strongly sheared magnetic field via helicity
+condensation. The diverging motions of supergranules converge opposite magnetic
+polarities at the PIL and drive the magnetic reconnection between footpoints of
+the sheared magnetic arcades to form an MFR. The magnetic network,
+negative-helicity MFR in the northern hemisphere, and fragmented-to-continuous
+formation process of magnetic dip regions are in agreement with observations.
+Although diverging supergranulations, differential rotation, and meridional
+flows are included, the simulation without the Coriolis effect can not produce
+an MFR or sheared arcades to host a prominence. Therefore Coriolis force is a
+key factor for helicity injection and the formation of magnetic structures of
+quiescent solar prominences.",2207.06598v1
+2022-11-28,Algorithms for magnetic symmetry operation search and identification of magnetic space group from magnetic crystal structure,"A crystal symmetry search is crucial for computational crystallography and
+materials science. Although algorithms and implementations for the crystal
+symmetry search have been developed, their extension to magnetic space groups
+(MSGs) remains limited. In this paper, algorithms for determining magnetic
+symmetry operations of magnetic crystal structures, identifying magnetic
+space-group types of given MSGs, searching for transformations to a BNS
+setting, and symmetrizing the magnetic crystal structures using the MSGs are
+presented. The determination of magnetic symmetry operations is numerically
+stable and is implemented with minimal modifications from the existing crystal
+symmetry search. Magnetic space-group types and transformations to the BNS
+setting are identified by a two-step approach combining space-group type
+identification and the use of affine normalizers. Point coordinates and
+magnetic moments of the magnetic crystal structures are symmetrized by
+projection operators for the MSGs. An implementation is distributed with a
+permissive free software license in spglib v2.0.2:
+https://github.com/spglib/spglib.",2211.15008v2
+2023-02-22,Controllable CVD-Growth of 2D Cr5Te8 Nanosheets with Thickness-Dependent Magnetic Domains,"As a typical 2D magnetic material with self-intercalated structure, Cr5Te8
+exhibits many fascinating magnetic properties. Although the ferromagnetism of
+2D Cr5Te8 has been reported, the study of its magnetic domain is still blank.
+Herein, we successfully fabricated 2D Cr5Te8 nanosheets with controlled
+thickness and lateral size by chemical vapor deposition (CVD). Then magnetic
+property measurement system suggested Cr5Te8 nanosheets possessing intense
+out-of-plane ferromagnetism with the Curie temperature of 179 K. Most
+importantly, we found magnetic bubbles and thickness-dependent maze-like
+magnetic domains by cryogenic magnetic force microscopy (MFM) for the first
+time. The domain width of the maze-like magnetic domains increases rapidly with
+decreasing sample thickness, while domain contrast decreases. This indicates
+dipolar interaction is the dominant role over exchange interaction and magnetic
+anisotropy. Our work not only paves a way for the controllable growth of 2D
+magnetic materials, but also suggests new directions for controlling magnetic
+phases and systematically adjusting domain properties.",2302.11422v2
+2023-03-11,Magnetic field imaging by cosmic-ray muons (Magic-$μ$) -- First feasibility simulation for strong magnetic fields,"We have proposed a novel application for cosmic-ray muography, called
+Magic-$\mu$, which is short for Magnetic field Imaging by Cosmic-ray Muons. The
+general goal of Magic-$\mu$ is to detect the presence of a magnetic field or
+magnetic flux density whose three-dimensional distribution is unknown.
+Depending on the application, Magic-$\mu$ can have three detection modes. The
+first is ""magnetic field imaging,"" which is detecting the presence of a
+magnetic field in specific voxels within a region of space. The other two
+modes, transmission and deflection, aim not only to detect the presence but
+also to measure the flux density of the magnetic field. We have performed a
+feasibility study using the PHITS Monte Carlo simulation code, for strong and
+weak magnetic fields. In this paper, we first give an overview of the concept
+and basic principles of magnetic field muography. Then, the results of the
+feasibility study on magnetic field imaging for a strong magnetic field (more
+than 500 mT) are presented.",2303.06290v3
+2023-05-30,Magnetic field regression using artificial neural networks for cold atom experiments,"Accurately measuring magnetic fields is essential for magnetic-field
+sensitive experiments in fields like atomic, molecular, and optical physics,
+condensed matter experiments, and other areas. However, since many experiments
+are conducted in an isolated vacuum environment that is inaccessible to
+experimentalists, it can be challenging to accurately determine the magnetic
+field. Here, we propose an efficient method for detecting magnetic fields with
+the assistance of an artificial neural network (NN). Instead of measuring the
+magnetic field directly at the desired location, we detect magnetic fields at
+several surrounding positions, and a trained NN can accurately predict the
+magnetic field at the target location. After training, we achieve a relative
+error of magnetic field magnitude (magnitude of error over the magnitude of
+magnetic field) below 0.3$\%$, and we successfully apply this method to our
+erbium quantum gas apparatus. This approach significantly simplifies the
+process of determining magnetic fields in isolated vacuum environments and can
+be applied to various research fields across a wide range of magnetic field
+magnitudes.",2305.18822v1
+2023-07-06,Plasmon-enhanced optical control of magnetism at the nanoscale via the inverse Faraday effect,"The relationship between magnetization and light has been the subject of
+intensive research for the past century, focusing on the impact of magnetic
+moments on light polarization. Conversely, the manipulation of magnetism
+through polarized light is being investigated to achieve all-optical control of
+magnetism in spintronics. While remarkable discoveries such as single pulse
+all-optical switching of the magnetization in thin films and sub-micrometer
+structures have been reported, the demonstration of local optical control of
+magnetism at the nanoscale has remained elusive. Here, we show that exciting
+gold nanodiscs with circularly polarized femtosecond laser pulses leads to the
+generation of sizeable local magnetic fields that enable ultrafast local
+control of the magnetization of an adjacent magnetic film. In addition, we find
+that the highest magnetic fields are generated when exciting the sample at a
+wavelength larger than that of the actual plasmonic resonance of the gold
+nanodiscs, so avoiding undesired heating effects due to absorption. Our study
+paves the way for light-driven control in nanoscale spintronic devices and
+provides important insights into the generation of magnetic fields in plasmonic
+nanostructures.",2307.03326v1
+2023-07-14,Parker Bounds on Monopoles with Arbitrary Charge from Galactic and Primordial Magnetic Fields,"We present a comprehensive study of Parker-type bounds on magnetic monopoles
+with arbitrary magnetic charge, including minicharged monopoles and magnetic
+black holes. We derive the bounds based on the survival of galactic magnetic
+fields, seed magnetic fields, as well as primordial magnetic fields. We find
+that monopoles with different magnetic charges are best constrained by
+different astrophysical systems: while monopoles with a Dirac charge are
+tightly constrained by seed galactic magnetic fields, minicharged monopoles are
+strongly constrained by primordial magnetic fields, and magnetic black holes by
+the density of dark matter. We also assess the viability of the various types
+of monopoles as dark matter, by studying whether they can cluster with galaxies
+hosting magnetic fields.",2307.07553v2
+2023-10-10,Skyrmions and magnetic bubbles in spin-orbit coupled metallic magnets,"Motivated by the observation of Skyrmion-like magnetic textures in 2D
+itinerant ferromagnets Fe$_n$GeTe$_2$ ($n \geq3$), we develop a microscopic
+model combining itinerant magnetism and spin-orbit coupling on a triangular
+lattice. The ground state of the model in the absence of magnetic field
+consists of filamentary magnetic domain walls revealing a striking similarity
+with our magnetic force microscopy experiments on Fe$_3$GeTe$_2$. In the
+presence of magnetic field, these filaments were found to break into large size
+magnetic bubbles in our experiments. We identify uniaxial magnetic anisotropy
+as an important parameter in the model that interpolates between magnetic
+Skyrmions and ferromagnetic bubbles. Consequently, our work uncovers new
+topological magnetic textures that merge properties of Skyrmions and
+ferromagnetic bubbles.",2310.06521v1
+2023-11-10,Exchange stiffness proportional to power of magnetization in permalloy co-doped with Mo and Cu,"The exchange stiffness of magnetic materials is one of the essential
+parameters governing magnetic texture and its dynamics in magnetic devices. The
+effect of single-element doping on exchange stiffness has been investigated for
+several doping elements for permalloy (NiFe alloy), a soft magnetic material
+whose soft magnetic properties can be controlled by doping. However, the impact
+of more practical multi-element doping on the exchange stiffness of permalloy
+is unknown. This study investigates the typical magnetic properties, including
+exchange stiffness, of permalloy systematically co-doped with Mo and Cu using
+broadband ferromagnetic resonance spectroscopy. We find that the exchange
+stiffness, which decreases with increasing doping levels, is proportional to a
+power of magnetization, which also decreases with increasing doping levels. The
+magnetization, $M_{\rm s}$, dependence of the exchange stiffness constant, $A$,
+of all the investigated samples, irrespective of the doping levels of each
+element, lies on a single curve expressed as $A\propto M_{\rm s}^n$ with
+exponent $n$ close to 2. This empirical power-law relationship provides a
+guideline for predicting unknown exchange stiffness in non-magnetic
+element-doped permalloy systems.",2311.05852v2
+2024-02-18,Deep learning methods for Hamiltonian parameter estimation and magnetic domain image generation in twisted van der Waals magnets,"The application of twist engineering in van der Waals magnets has opened new
+frontiers in the field of two-dimensional magnetism, yielding distinctive
+magnetic domain structures. Despite the introduction of numerous theoretical
+methods, limitations persist in terms of accuracy or efficiency due to the
+complex nature of the magnetic Hamiltonians pertinent to these systems. In this
+study, we introduce a deep-learning approach to tackle these challenges.
+Utilizing customized, fully connected networks, we develop two
+deep-neural-network kernels that facilitate efficient and reliable analysis of
+twisted van der Waals magnets. Our regression model is adept at estimating the
+magnetic Hamiltonian parameters of twisted bilayer CrI3 from its magnetic
+domain images generated through atomistic spin simulations. The generative
+model excels in producing precise magnetic domain images from the provided
+magnetic parameters. The trained networks for these models undergo thorough
+validation, including statistical error analysis and assessment of robustness
+against noisy injections. These advancements not only extend the applicability
+of deep-learning methods to twisted van der Waals magnets but also streamline
+future investigations into these captivating yet poorly understood systems.",2402.11434v1
+2001-08-29,Jet Collimation by Small-Scale Magnetic Fields,"A popular model for jet collimation is associated with the presence of a
+large-scale and predominantly toroidal magnetic field originating from the
+central engine (a star, a black hole, or an accretion disk). Besides the
+problem of how such a large-scale magnetic field is generated, in this model
+the jet suffers from the fatal long-wave mode kink magnetohydrodynamic
+instability. In this paper we explore an alternative model: jet collimation by
+small-scale magnetic fields. These magnetic fields are assumed to be local,
+chaotic, tangled, but are dominated by toroidal components. Just as in the case
+of a large-scale toroidal magnetic field, we show that the ``hoop stress'' of
+the tangled toroidal magnetic fields exerts an inward force which confines and
+collimates the jet. The magnetic ``hoop stress'' is balanced either by the gas
+pressure of the jet, or by the centrifugal force if the jet is spinning. Since
+the length-scale of the magnetic field is small (< the cross-sectional radius
+of the jet << the length of the jet), in this model the jet does not suffer
+from the long-wave mode kink instability. Many other problems associated with
+the large-scale magnetic field are also eliminated or alleviated for
+small-scale magnetic fields. Though it remains an open question how to generate
+and maintain the required small-scale magnetic fields in a jet, the scenario of
+jet collimation by small-scale magnetic fields is favored by the current study
+on disk dynamo which indicates that small-scale magnetic fields are much easier
+to generate than large-scale magnetic fields.",0108469v1
+2003-10-20,Cyclic evolution and reversal of the solar magnetic field. I. The large-scale magnetic fields,"On the base of the solar magnetic field measurements obtained in Stanford in
+1976--2003 the properties of the cyclic evolution of the large-scale magnetic
+field are investigated. Some regularities are found in longitudinal and
+latitudinal evolution of the magnetic field in cycles 21, 22 and 23. The cyclic
+development of the large-scale magnetic field can be divided into two main
+phases. The phase I, which includes a period approximately from two years
+before and until three years after the maximum of the solar cycle, is studied
+in detail. It is found that before the reversal of the large-scale magnetic
+field the neutral line of the magnetic field in antipodal longitudinal
+intervals shifts from the equator to opposite directions in cycles 21 and 22,
+but not in cycle 23. During the sign reversal of the large-scale magnetic field
+in cycles 21 and 22 in the antipodal longitudinal intervals the magnetic field
+of opposite polarity is observed in all latitudes, thereby forming an
+equatorial dipole. After the magnetic field reversal a longitudinal oscillation
+of the magnetic neutral line with regard to the equator takes place, which has
+a period about 2 years and damps to the minimum of the 11-year cycle. The
+intervening longitudinal intervals of the large-scale magnetic field correspond
+to positions of the active longitudes of sunspot activity, thus indicating a
+close connection of the large-scale and the local magnetic fields. In evolution
+of the large-scale magnetic field a periodicity with period $1.23\pm0.16$ year
+is revealed, which is close to the period found by helioseismological methods
+in variations of the solar rotation near the tachocline.",0310539v1
+2009-03-16,Relationship between photospheric currents and coronal magnetic helicity for force-free bipolar fields,"The origin and evolution of the magnetic helicity in the solar corona are not
+well understood. For instance, the magnetic helicity of an active region is
+often about $10^{42}$ Mx$^2$ ($10^{26}$ Wb$^{2}$), but the observed processes
+whereby it is thought to be injected into the corona do not yet provide an
+accurate estimate of the resulting magnetic helicity budget or time evolution.
+The variation in magnetic helicity is important for understanding the physics
+of flares, coronal mass ejections, and their associated magnetic clouds. To
+shed light on this topic, we investigate here the changes in magnetic helicity
+due to electric currents in the corona for a single twisted flux tube that may
+model characteristic coronal structures such as active region filaments,
+sigmoids, or coronal loops. For a bipolar photospheric magnetic field and
+several distributions of current, we extrapolated the coronal field as a
+nonlinear force-free field. We then computed the relative magnetic helicity, as
+well as the self and mutual helicities. Starting from a magnetic configuration
+with a moderate amount of current, the amount of magnetic helicity can increase
+by 2 orders of magnitude when the maximum current strength is increased by a
+factor of 2. The high sensitivity of magnetic helicity to the current density
+can partially explain discrepancies between measured values on the photosphere,
+in the corona, and in magnetic clouds. Our conclusion is that the magnetic
+helicity strongly depends on both the strength of the current density and also
+on its distribution. Only improved measurements of current density at the
+photospheric level will advance our knowledge of the magnetic helicity content
+in the solar atmosphere.",0903.2697v1
+2011-03-29,Relationship between vertical and horizontal magnetic fields in the quiet Sun,"Vertical magnetic fields have been known to exist in the internetwork region
+for decades, while the properties of horizontal magnetic fields have recently
+been extensively investigated with \textit{Hinode}. Vertical and horizontal
+magnetic fields in the internetwork region are considered to be separate
+entities and have thus far not been investigated in a unified way. We discover
+clear positional association between the vertical and horizontal magnetic
+fields in the internetwork region with \textit{Hinode}. Essentially all of the
+horizontal magnetic patches are associated with the vertical magnetic patches.
+Alternatively, half of the vertical magnetic patches accommodate the horizontal
+magnetic patches. These horizontal patches are located around the borders of
+the vertical patches. The intrinsic magnetic field strength as obtained with
+the Stokes $V$ line ratio inside the horizontal patches is weak, and is in
+sub-equipartition field regime ($B<700$ G), while the field strength outside
+the horizontal patches ranges from weak to strong (kG) fields. Vertical
+magnetic patches are known to be concentrated on mesogranular and supergranular
+boundaries, while the horizontal magnetic patches are found only on the
+mesogranular boundaries. These observations provide us with new information on
+the origin of the vertical and horizontal internetwork magnetic fields, in a
+unified way. We conjecture that internetwork magnetic fields are provided by
+emergence of small-scale flux tubes with bipolar footpoints, and the vertical
+magnetic fields of the footpoints are intensified to kG fields due to
+convective collapse. Resultant strong vertical fields are advected by the
+supergranular flow, and eventually form the network fields.",1103.5556v1
+2011-11-30,Relation of Astrophysical Turbulence and Magnetic Reconnection,"Astrophysical fluids are generically turbulent and this must be taken into
+account for most transport processes. We discuss how the preexisting turbulence
+modifies magnetic reconnection and how magnetic reconnection affects the MHD
+turbulent cascade. We show the intrinsic interdependence and interrelation of
+magnetic turbulence and magnetic reconnection, in particular, that strong
+magnetic turbulence in 3D requires reconnection and 3D magnetic turbulence
+entails fast reconnection. We follow the approach in Eyink, Lazarian & Vishniac
+2011 to show that the expressions of fast magnetic reconnection in Lazarian &
+Vishniac 1999 can be recovered if Richardson diffusion of turbulent flows is
+used instead of ordinary Ohmic diffusion. This does not revive, however, the
+concept of magnetic turbulent diffusion which assumes that magnetic fields can
+be mixed up in a passive way down to a very small dissipation scales. On the
+contrary, we are dealing the reconnection of dynamically important magnetic
+field bundles which strongly resist bending and have well defined mean
+direction weakly perturbed by turbulence. We argue that in the presence of
+turbulence the very concept of flux-freezing requires modification. The
+diffusion that arises from magnetic turbulence can be called reconnection
+diffusion as it based on reconnection of magnetic field lines. The reconnection
+diffusion has important implications for the continuous transport processes in
+magnetized plasmas and for star formation. In addition, fast magnetic
+reconnection in turbulent media induces the First order Fermi acceleration of
+energetic particles, can explain solar flares and gamma ray bursts. However,
+the most dramatic consequence of these developments is the fact that the
+standard flux freezing concept must be radically modified in the presence of
+turbulence.",1112.0022v1
+2012-10-13,Full-disk nonlinear force-free field extrapolation of SDO/HMI and SOLIS/VSM magnetograms,"Extrapolation codes in Cartesian geometry for modelling the magnetic field in
+the corona do not take the curvature of the Sun's surface into account and can
+only be applied to relatively small areas, e.g., a single active region. We
+compare the analysis of the photospheric magnetic field and subsequent
+force-free modeling based on full-disk vector maps from Helioseismic and
+Magnetic Imager (HMI) on board solar dynamics observatory (SDO) and Vector
+Spectromagnetograph (VSM) of the Synoptic Optical Long-term Investigations of
+the Sun (SOLIS). We use Helioseismic and Magnetic Imager and Vector
+Spectromagnetograph photospheric magnetic field measurements to model the
+force-free coronal field above multiple solar active regions, assuming magnetic
+forces to dominate. We solve the nonlinear force-free field equations by
+minimizing a functional in spherical coordinates over a full disk excluding the
+poles. After searching for the optimum modeling parameters for the particular
+data sets, we compare the resulting nonlinear force-free model fields. We
+compare quantities like the total magnetic energy content and free magnetic
+energy, the longitudinal distribution of the magnetic pressure and surface
+electric current density using our spherical geometry extrapolation code. The
+magnetic field lines obtained from nonlinear force-free extrapolation based on
+Helioseismic and Magnetic Imager and Vector Spectromagnetograph data have good
+agreement. However, the nonlinear force-free extrapolation based on
+Helioseismic and Magnetic Imager data have more contents of total magnetic
+energy, free magnetic energy, the longitudinal distribution of the magnetic
+pressure and surface electric current density compared to the one from Vector
+Spectromagnetograph data.",1210.3668v1
+2012-12-04,Evolution of Primordial Magnetic Fields from Phase Transitions,"We consider the evolution of primordial magnetic fields generated during
+cosmological, electroweak or QCD, phase transitions. We assume that the
+magnetic field generation can be described as an injection of magnetic energy
+to cosmological plasma at a given scale determined by the moment of magnetic
+field generation. A high Reynolds number ensures strong coupling between
+magnetic field and fluid motions. The subsequent evolution of the magnetic
+field is governed by decaying hydromagnetic turbulence. Both our numerical
+simulations and a phenomenological description allow us to recover ""universal""
+laws for the decay of magnetic energy and the growth of magnetic correlation
+length in the turbulent (low viscosity) regime. In particular, we show that
+during the radiation dominated epoch, energy and correlation length of
+non-helical magnetic fields scale as conformal time to the powers -1/2 and
++1/2, respectively. For helical magnetic fields, energy and correlation length
+scale as conformal time to the powers -1/3 and +2/3, respectively. The
+universal decay law of the magnetic field implies that the strength of magnetic
+field generated during the QCD phase transition could reach $\sim 10^{-9}$\,G
+with the present day correlation length $\sim 50$ kpc. The fields generated at
+the electroweak phase transition could be as strong as $\sim 10^{-10}$ G with
+correlation lengths reaching $\sim 0.3$\,kpc. These values of the magnetic
+fields are consistent with the lower bounds of the extragalactic magnetic
+fields.",1212.0596v2
+2014-12-10,Joint inverse cascade of magnetic energy and magnetic helicity in MHD turbulence,"We show that oppositely directed fluxes of energy and magnetic helicity
+coexist in the inertial range in fully developed magnetohydrodynamic (MHD)
+turbulence with small-scale sources of magnetic helicity. Using a helical shell
+model of MHD turbulence, we study the high Reynolds number magnetohydrodynamic
+turbulence for helicity injection at a scale that is much smaller than the
+scale of energy injection. In a short range of scales larger than the forcing
+scale of magnetic helicity, a bottleneck-like effect appears, which results in
+a local reduction of the spectral slope. The slope changes in a domain with a
+high level of relative magnetic helicity, which determines that part of the
+magnetic energy related to the helical modes at a given scale. If the relative
+helicity approaches unity, the spectral slope tends to $-3/2$. We show that
+this energy pileup is caused by an inverse cascade of magnetic energy
+associated with the magnetic helicity. This negative energy flux is the
+contribution of the pure magnetic-to-magnetic energy transfer, which vanishes
+in the non-helical limit. In the context of astrophysical dynamos, our results
+indicate that a large-scale dynamo can be affected by the magnetic helicity
+generated at small scales. The kinetic helicity, in particular, is not involved
+in the process at all. An interesting finding is that an inverse cascade of
+magnetic energy can be provided by a small-scale source of magnetic helicity
+fluctuations without a mean injection of magnetic helicity.",1412.3225v1
+2015-04-29,The formation of regular interarm magnetic fields in spiral galaxies,"Observations of regular magnetic fields in several nearby galaxies reveal
+magnetic arms situated between the material arms. The nature of these magnetic
+arms is a topic of active debate. Previously we found a hint that taking into
+account the effects of injections of small-scale magnetic fields generated,
+e.g., by turbulent dynamo action, into the large-scale galactic dynamo can
+result in magnetic arm formation. We now investigate the joint roles of an
+arm/interarm turbulent diffusivity contrast and injections of small-scale
+magnetic field on the formation of large-scale magnetic field (""magnetic arms"")
+in the interarm region. We use the relatively simple ""no-$z$"" model for the
+galactic dynamo. This involves projection on to the galactic equatorial plane
+of the azimuthal and radial magnetic field components; the field component
+orthogonal to the galactic plane is estimated from the solenoidality condition.
+We find that addition of diffusivity gradients to the effect of magnetic field
+injections makes the magnetic arms much more pronounced. In particular, the
+regular magnetic field component becomes larger in the interarm space compared
+to that within the material arms.The joint action of the turbulent diffusivity
+contrast and small-scale magnetic field injections (with the possible
+participation of other effects previously suggested) appears to be a plausible
+explanation for the phenomenon of magnetic arms.",1504.07824v3
+2016-06-08,Simulation and experiments of Stacks of High Temperature Superconducting Coated Conductors Magnetized by Pulsed Field Magnetization with Multi-Pulse Technique,"High temperature superconducting (HTS) bulks or stacks of coated conductors
+(CCs) can be magnetized to become trapped field magnets (TFMs). The magnetic
+fields of such TFMs can break the limitation of conventional magnets (<2 T), so
+they show potential for improving the performance of many electrical
+applications that use permanent magnets like rotating machines. Towards
+practical or commercial use of TFMs, effective in situ magnetization is one of
+the key issues. The pulsed field magnetization (PFM) is among the most
+promising magnetization methods in virtue of its compactness, mobility and low
+cost. However, due to the heat generation during the magnetization, the trapped
+field and flux acquired by PFM usually cannot achieve the full potential of a
+sample (acquired by the field cooling or zero field cooling method). The
+multi-pulse technique was found to effectively improve the trapped field by PFM
+in practice. In this work, a systematic study on the PFM with successive pulses
+is presented. A 2D electromagnetic-thermal coupled model with comprehensive
+temperature dependent parameters is used to simulate a stack of CCs magnetized
+by successive magnetic pulses. An overall picture is built to show how the
+trapped field and flux evolve with different pulse sequences and the evolution
+patterns are analyzed. Based on the discussion, an operable magnetization
+strategy of PFM with successive pulses is suggested to provide more trapped
+field and flux. Finally, experimental results of a stack of CCs magnetized by
+typical pulse sequences are presented for demonstration.",1606.07732v1
+2017-08-25,Statistics of magnetic field measurements and evolution of magnetic field of OBA stars,"We review the measurements of magnetic fields of OBA stars. Based on these
+data we confirm that magnetic fields are distributed according to a lognormal
+law with a mean log(B)=-0.5 (B in kG) with a standard deviation sigma=0.5. The
+shape of the magnetic field distribution is similar to that for neutron stars.
+This finding is in favor of the hypothesis that the magnetic field of a neutron
+star is determined mainly by the magnetic field of its predecessor, the massive
+OB star. Further, we model the evolution of an ensemble of magnetic massive
+stars in the Galaxy. We use our own population synthesis code to obtain the
+distribution of stellar radii, ages, masses, temperatures, effective magnetic
+fields and magnetic fluxes from the pre-main sequence (PMS) via zero age main
+sequence (ZAMS) up to the terminal age main sequence (TAMS) stages. A
+comparison of the obtained in our model magnetic field distribution (MFD) with
+that obtained from the recent measurements of the stellar magnetic field allows
+us to conclude that the evolution of magnetic fields of massive stars is slow
+if not absent. The shape of the real MFD shows no indications of the magnetic
+desert proposed previously. Based on this finding we argue that the observed
+fraction of magnetic stars is determined by physical conditions at the PMS
+stage of stellar evolution.",1708.07816v2
+2018-05-09,The Effects of Magnetic Field Strength on Properties of Wind Generated from Hot Accretion Flow,"Observations indicate that wind can be generated in hot accretion flow. By
+performing numerical simulations, Yuan et al. studied the detailed properties
+of wind generated from weakly magnetized accretion flow. However, properties of
+wind generated from strongly magnetized hot accretion flow have not been
+studied. In this paper, we study the properties of wind generated from both
+weakly and strongly magnetized accretion flow. We focus on how the magnetic
+field strength affects the wind properties. We solve time-steady
+two-dimensional magnetohydrodynamic (MHD) equations of black hole accretion in
+the presence of large-scale magnetic field. We assume self-similarity in radial
+direction. The magnetic field is assumed to be evenly symmetric with the
+equatorial plane. We find that wind exists in both weakly and strongly
+magnetized accretion flow. When magnetic field is weak (magnetic pressure is
+more than 2 orders of magnitude smaller than gas pressure), wind is driven by
+gas pressure gradient and centrifugal forces. When magnetic field is strong
+(magnetic pressure is slightly smaller than gas pressure), wind is driven by
+gas pressure gradient and magnetic pressure gradient forces. The power of wind
+in strongly magnetized case is just slightly larger than that in weakly
+magnetized case. The power of wind lies in a range $ P_W \sim 10^{-4}-10^{-3}
+\dot M_{\rm in} c^2 $, with $ \dot M_{\rm in} $ and $ c $ being mass inflow
+rate and speed of light, respectively. The possible role of wind in active
+galactic nuclei feedback is briefly discussed.",1805.03378v1
+2011-11-15,Spin waves in nanosized magnetic films,"We have studied spin excitations in nanosized magnetic films in the
+Heisenberg model with magnetic dipole and exchange interactions by the spin
+operator diagram technique. Dispersion relations of spin waves in thin magnetic
+films (in two-dimensional magnetic monolayers and in two-layer magnetic films)
+and the spin-wave resonance spectrum in N-layer structures are found. For thick
+magnetic films generalized Landau-Lifshitz equations are derived from first
+principles. Landau-Lifshitz equations have the integral (pseudodifferential)
+form, but not differential one. Spin excitations are determined by simultaneous
+solution of the Landau-Lifshitz equations and the equation for the
+magnetostatic potential. For normal magnetized ferromagnetic films the spin
+wave damping has been calculated in the one-loop approximation for a diagram
+expansion of the Green functions at low temperature. In thick magnetic films
+the magnetic dipole interaction makes a major contribution to the relaxation of
+long-wavelength spin waves. Thin films have a region of low relaxation of
+long-wavelength spin waves. In thin magnetic films four-spin-wave processes
+take place and the exchange interaction makes a major contribution to the
+damping. It is found that the damping of spin waves propagating in magnetic
+monolayer is proportional to the quadratic dependence on the temperature and is
+very low for spin waves with small wavevectors. Spin-wave devices on the base
+of nanosized magnetic films are proposed -- tunable narrow-band spin-wave
+filters with high quality at the microwave frequency range and field-effect
+transistor (FET) structures contained nanosized magnetic films under the gate
+electrode. Spin-wave resonances in nanosized magnetic films can be used to
+construct FET structures operating in Gigahertz and Terahertz frequency bands.",1111.3532v1
+2014-06-21,Quark stars under strong magnetic fields,"Within the confined isospin- and density-dependent mass model, we study the
+properties of strange quark matter (SQM) and quark stars (QSs) under strong
+magnetic fields. The equation of state of SQM under a constant magnetic field
+is obtained self-consistently and the pressure perpendicular to the magnetic
+field is shown to be larger than that parallel to the magnetic field, implying
+that the properties of magnetized QSs generally depend on both the strength and
+the orientation of the magnetic fields distributed inside the stars. Using a
+density-dependent magnetic field profile which is introduced to mimic the
+magnetic field strength distribution in a star, we study the properties of
+static spherical QSs by assuming two extreme cases for the magnetic field
+orientation in the stars, i.e., the radial orientation in which the local
+magnetic fields are along the radial direction and the transverse orientation
+in which the local magnetic fields are randomly oriented but perpendicular to
+the radial direction. Our results indicate that including the magnetic fields
+with radial (transverse) orientation can significantly decrease (increase) the
+maximum mass of QSs, demonstrating the importance of the magnetic field
+orientation inside the magnetized compact stars.",1406.5610v2
+2017-12-13,Studying the transfer of magnetic helicity in solar active regions with the connectivity-based helicity flux density method,"In the solar corona, magnetic helicity slowly and continuously accumulates in
+response to plasma flows tangential to the photosphere and magnetic flux
+emergence through it. Analyzing this transfer of magnetic helicity is key for
+identifying its role in the dynamics of active regions (ARs). The
+connectivity-based helicity flux density method was recently developed for
+studying the 2D and 3D transfer of magnetic helicity in ARs. The method takes
+into account the 3D nature of magnetic helicity by explicitly using knowledge
+of the magnetic field connectivity, which allows it to faithfully track the
+photospheric flux of magnetic helicity. Because the magnetic field is not
+measured in the solar corona, modeled 3D solutions obtained from force-free
+magnetic field extrapolations must be used to derive the magnetic connectivity.
+Different extrapolation methods can lead to markedly different 3D magnetic
+field connectivities, thus questioning the reliability of the
+connectivity-based approach in observational applications. We address these
+concerns by applying this method to the isolated and internally complex AR
+11158 with different magnetic field extrapolation models. We show that the
+connectivity-based calculations are robust to different extrapolation methods,
+in particular with regards to identifying regions of opposite magnetic helicity
+flux. We conclude that the connectivity-based approach can be reliably used in
+observational analyses and is a promising tool for studying the transfer of
+magnetic helicity in ARs and relate it to their flaring activity.",1712.04691v1
+2019-09-05,"The Magnetic Early B-type Stars III: A main sequence magnetic, rotational, and magnetospheric biography","Magnetic confinement of stellar winds leads to the formation of
+magnetospheres, which can be sculpted into Centrifugal Magnetospheres (CMs) by
+rotational support of the corotating plasma. The conditions required for the
+CMs of magnetic early B-type stars to yield detectable emission in H$\alpha$ --
+the principal diagnostic of these structures -- are poorly constrained. A key
+reason is that no detailed study of the magnetic and rotational evolution of
+this population has yet been performed. Using newly determined rotational
+periods, modern magnetic measurements, and atmospheric parameters determined
+via spectroscopic modelling, we have derived fundamental parameters, dipolar
+oblique rotator models, and magnetospheric parameters for 56 early B-type
+stars. Comparison to magnetic A- and O-type stars shows that the range of
+surface magnetic field strength is essentially constant with stellar mass, but
+that the unsigned surface magnetic flux increases with mass. Both the surface
+magnetic dipole strength and the total magnetic flux decrease with stellar age,
+with the rate of flux decay apparently increasing with stellar mass. We find
+tentative evidence that multipolar magnetic fields may decay more rapidly than
+dipoles. Rotational periods increase with stellar age, as expected for a
+magnetic braking scenario. Without exception, all stars with H$\alpha$ emission
+originating in a CM are 1) rapid rotators, 2) strongly magnetic, and 3) young,
+with the latter property consistent with the observation that magnetic fields
+and rotation both decrease over time.",1909.02530v1
+2020-04-24,Observation of magnetic domain and bubble structures in magnetoelectric Sr$_3$Co$_2$Fe$_{24}$O$_{41}$,"The magnetic domain and bubble structures in the Z-type hexaferrite
+Sr$_3$Co$_2$Fe$_{24}$O$_{41}$ were investigated using Lorentz microscopy. This
+hexaferrite exhibits a room-temperature magnetoelectric effect that is
+attributed to its transverse conical spin structure (TC phase). Upon heating,
+the TC phase transforms into a ferrimagnetic phase with magnetic moments in the
+hexagonal $ab$ plane between 410 and 480 K (FM2 phase) and into another
+ferrimagnetic phase with moments parallel to the $c$ axis between 490 and 680 K
+(FM1 phase). Accordingly, in this study, the magnetic domain structures in
+Sr$_3$Co$_2$Fe$_{24}$O$_{41}$ were observed to change dramatically with
+temperature. In the TC phase, irregular fine magnetic domains were observed
+after cooling the specimen from the FM2 to TC phase. In the FM1 phase, striped
+magnetic domain walls with pairs of bright and dark contrast were formed
+parallel to the $c$ axis. Upon applying an external magnetic field, the striped
+magnetic domain walls transformed into magnetic bubbles. The topology of the
+magnetic bubbles was dependent on the angle between the external magnetic field
+($H$) direction and the easy $c$ axis. Namely, magnetic bubbles with the
+topological number $N$ = 1 (type I) were created for $H//c$, whereas magnetic
+bubbles with $N$ = 0 (type II) were created when the magnetic field was tilted
+from the c axis by 5{\deg}. We attribute the high magnetocrystalline anisotropy
+of Sr$_3$Co$_2$Fe$_{24}$O$_{41}$ to the emergence of magnetic bubbles in the
+FM1 phase.",2004.11591v1
+2017-08-22,A pico-Tesla magnetic sensor with PZT bimorph and permanent magnet proof mass,"Ferromagnetic-ferroelectric composites have attracted interests in recent
+years for use as magnetic field sensors. The sensing is based on
+magneto-electric (ME) coupling between the electric and magnetic subsystems and
+is mediated by mechanical strain. Such sensors for AC magnetic fields require a
+bias magnetic field to achieve pT-sensitivity. Here we discuss measurements and
+theory for a novel passive, AC magnetic sensor that does not require a bias
+magnetic field and is based on a PZT bimorph with a permanent magnet proof
+mass. Mechanical strain on the PZT bimorph in this case is produced by
+interaction between the applied AC magnetic field and remnant magnetization of
+the permanent magnet, resulting in an induced voltage across PZT. Our studies
+have been performed on sensors with a bimorph of oppositely poled PZT platelets
+and a NdFeB permanent magnet proof mass. Magnetic floor noise N on the order of
+100 pT per sqrHz and 10 nT per sqrHz are measured at 1 Hz and 10 Hz,
+respectively. When the AC magnetic field is applied at the bending resonance of
+40 Hz for the bimorph, the measured N 700 pT per sqrHz. We also discuss a
+theory for the magneto-electro-mechanical coupling at low frequency and bending
+resonance in the sensor and theoretical estimates of ME voltage coefficients
+are in very good agreement with the data.",1709.01794v1
+2018-08-08,Magnetic Gradiometer for Detection of Zero- and Ultralow-Field Nuclear Magnetic Resonance,"Magnetic sensors are important for detecting nuclear magnetization signals in
+nuclear magnetic resonance (NMR). As a complementary analysis tool to
+conventional high-field NMR, zero- and ultralow-field (ZULF) NMR detects
+nuclear magnetization signals in the sub-microtesla regime. Current ZULF NMR
+systems are always equipped with high-quality magnetic shieldings to ensure
+that ambient magnetic field noise does not dwarf the magnetization signal. An
+alternative approach is to separate the magnetization signal from the noise
+based on their differing spatial profiles, as can be achieved using a magnetic
+gradiometer. Here, we present a gradiometric ZULF NMR spectrometer with a
+magnetic gradient noise of 17 fT_{rms}{cm}^{-1}{Hz}^{-1/2} in the frequency
+range of 100-400 Hz, based on a single vapor cell (0.7x0.7x1.0{cm}^3). With
+applied white magnetic-field noise, we show that the gradiometric spectrometer
+achieves 13-fold enhancement in the signal-to-noise ratio (SNR) compared to the
+single-channel configuration. By reducing the influence of common-mode magnetic
+noise, this work enables the use of compact and low-cost magnetic shields.
+Gradiometric detection may also prove to be beneficial for eliminating
+systematic errors in ZULF-NMR experiments searching for exotic spin-dependent
+interactions and molecular parity violation.",1808.02743v1
+2019-01-30,Comparative Study of the Surface Potential of Magnetic and Non-magnetic Spherical Objects in a Magnetized RF Discharge Plasma,"We report measurements of the time-averaged surface floating potential of
+magnetic and non-magnetic spherical probes (or large dust particles) immersed
+in a magnetized capacitively coupled discharge. In this study, the size of the
+spherical probes is taken greater than the Debye length. The surface potential
+of a spherical probe first increases, i.e. becomes more negative at low
+magnetic field (B $<$ 0.05 T), attains a maximum value and decreases with
+further increase of the magnetic field strength (B $>$ 0.05 T). The rate of
+change of the surface potential in the presence of a B-field mainly depends on
+the background plasma and types of material of the objects. The results show
+that the surface potential of the magnetic sphere is higher (more negative)
+compared to the non-magnetic spherical probe. Hence, the smaller magnetic
+sphere collects more negative charges on its surface than a bigger non-magnetic
+sphere in a magnetized plasma. The different sized spherical probes have nearly
+the same surface potential above a threshold magnetic field (B $>$ 0.03 T),
+implicating a smaller role of size dependence on the surface potential of
+spherical objects. The variation of the surface potential of the spherical
+probes is understood on the basis of a modification of the collection currents
+to their surface due to charge confinement and cross-field diffusion in the
+presence of an external magnetic field.",1901.10955v4
+2019-02-27,Relative magnetic field line helicity,"Context. Magnetic helicity is an important quantity in studies of magnetized
+plasmas as it provides a measure of the geometrical complexity of the magnetic
+field in a given volume. A more detailed description of the spatial
+distribution of magnetic helicity is given by the field line helicity that
+expresses the amount of helicity associated to individual field lines, rather
+than in the full analysed volume. Aims. Magnetic helicity is not a
+gauge-invariant quantity in general, unless it is computed with respect to a
+reference field, yielding the so called relative magnetic helicity. The field
+line helicity corresponding to the relative magnetic helicity has only been
+examined under specific conditions so far. This work aims to define the field
+line helicity corresponding to relative magnetic helicity in the most general
+way. In addition to its general form, we provide the expression for the
+relative magnetic field line helicity in a few commonly used gauges, and
+reproduce known results as a limit of our general formulation. Methods. By
+starting from the definition of relative magnetic helicity, we derive the
+corresponding field line helicity, and we note the assumptions it is based on.
+Results. We check that the developed quantity reproduces relative magnetic
+helicity by using three different numerical simulations. For these cases we
+also show the morphology of field line helicity in the volume, and on the
+photospheric plane. As an application to solar situations, we compare the
+morphology of field line helicity on the photosphere with that of the
+connectivity-based helicity flux density in two reconstructions of an active
+region's magnetic field. We discuss how the derived relative magnetic field
+line helicity has a wide range of applications, notably in solar physics and
+magnetic reconnection studies.",1902.10410v1
+2020-06-12,Odd-even layer-number effect and layer-dependent magnetic phase diagrams in MnBi2Te4,"The intrinsic magnetic layered topological insulator MnBi2Te4 with nontrivial
+topological properties and magnetic order has become a promising system for
+exploring exotic quantum phenomena such as quantum anomalous Hall effect.
+However, the layer-dependent magnetism of MnBi2Te4, which is fundamental and
+crucial for further exploration of quantum phenomena in this system, remains
+elusive. Here, we use polar reflective magnetic circular dichroism
+spectroscopy, combined with theoretical calculations, to obtain an in-depth
+understanding of the layer-dependent magnetic properties in MnBi2Te4. The
+magnetic behavior of MnBi2Te4 exhibits evident odd-even layer-number effect,
+i.e. the oscillations of the coercivity of the hysteresis loop (at {\mu}0Hc)
+and the spin-flop transition (at {\mu}0H1), concerning the Zeeman energy and
+magnetic anisotropy energy. In the even-number septuple layers, an anomalous
+magnetic hysteresis loop is observed, which is attributed to the
+thickness-independent surface-related magnetization. Through the linear-chain
+model, we can clarify the odd-even effect of the spin-flop field and determine
+the evolution of magnetic states under the external magnetic field. The
+mean-field method also allows us to trace the experimentally observed magnetic
+phase diagrams to the magnetic fields, layer numbers and especially,
+temperature. Overall, by harnessing the unusual layer-dependent magnetic
+properties, our work paves the way for further study of quantum properties of
+MnBi2Te4.",2006.07216v1
+2021-05-31,Theoretical development in the viscosity of ferrofluid,"The viscosity of ferrofluid has an important role in liquid sealing of the
+hard disk drives, biomedical applications as drug delivery, hyperthermia, and
+magnetic resonance imaging. In the absence of a magnetic field, the viscosity
+of ferrofluid depends on the volume concentration of magnetic nanoparticles
+including surfactant layers. However, under the influence of a stationary
+magnetic field, the viscosity of ferrofluid depends on the angle between the
+applied magnetic field and vorticity in the flow. If this angle is 90o, then
+there is a maximum increase in the viscosity. If the magnetic field and the
+vorticity in the flow are parallel to each other, then there is no change in
+the viscosity since the applied magnetic field does not change the speed of the
+rotation of magnetic nanoparticles in the fluid. The viscosity of ferrofluid in
+the presence of an alternating magnetic field demonstrates interesting
+behavior. When field frequency matches with the relaxation time, known as
+resonance condition, then there is no impact of an alternating magnetic field
+in the viscosity of ferrofluid. If the frequency of an alternating magnetic
+field is less than resonance frequency, then an alternating magnetic field
+increases the viscosity of ferrofluid. Using higher frequency than resonance
+condition reduces the viscosity of ferrofluid and researchers reported this
+incident as the negative viscosity effect. If the frequency of an alternating
+magnetic field tends to infinite, then ferrofluid ceases to feel a magnetic
+field. In this case, there is no impact of an alternating magnetic field on the
+viscosity of ferrofluid.",2105.14721v1
+2021-08-19,Quantized edge magnetizations and their symmetry protection in one-dimensional quantum spin systems,"The bulk electric polarization works as a nonlocal order parameter that
+characterizes topological quantum matters. Motivated by a recent paper [H.
+Watanabe \textit{et al.}, Phys. Rev. B {\bf 103}, 134430 (2021)], we discuss
+magnetic analogs of the bulk polarization in one-dimensional quantum spin
+systems, that is, quantized magnetizations on the edges of one-dimensional
+quantum spin systems.The edge magnetization shares the topological origin with
+the fractional edge state of the topological odd-spin Haldane phases. Despite
+this topological origin, the edge magnetization can also appear in
+topologically trivial quantum phases. We develop straightforward field
+theoretical arguments that explain the characteristic properties of the edge
+magnetization. The field theory shows that a U(1) spin-rotation symmetry and a
+site-centered or bond-centered inversion symmetry protect the quantization of
+the edge magnetization. We proceed to discussions that quantum phases on
+nonzero magnetization plateaus can also have the quantized edge magnetization
+that deviates from the magnetization density in bulk. We demonstrate that the
+quantized edge magnetization distinguishes two quantum phases on a
+magnetization plateau separated by a quantum critical point. The edge
+magnetization exhibits an abrupt stepwise change from zero to $1/2$ at the
+quantum critical point because the quantum phase transition occurs in the
+presence of the symmetries protecting the quantization of the edge
+magnetization. We also show that the quantized edge magnetization can result
+from the spontaneous ferrimagnetic order.",2108.08458v2
+2021-08-27,Effects of anisotropy on strongly magnetized neutron and strange quark stars in general relativity,"We investigate the properties of anisotropic, spherically symmetric compact
+stars, especially neutron stars and strange quark stars, made of strongly
+magnetized matter. The neutron stars are described by SLy equation of state,
+the strange quark stars by an equation of state based on the MIT Bag model. The
+stellar models are based on an a priori assumed density dependence of the
+magnetic field and thus anisotropy. Our study shows that not only the presence
+of a strong magnetic field and anisotropy, but also the orientation of the
+magnetic field itself, have an important influence on the physical properties
+of stars. Two possible magnetic field orientations are considered, a radial
+orientation, where the local magnetic fields point in the radial direction, and
+a transverse orientation, where the local magnetic fields are perpendicular to
+the radial direction. Interestingly, we find that for a transverse orientation
+of the magnetic field, the stars become more massive with increasing anisotropy
+and magnetic field strength and increase in size, since the repulsive,
+effective anisotropic force increases in this case. In the case of a radially
+orientated magnetic field, however, the masses and radii of the stars decrease
+with increasing magnetic field strength, because of the decreasing effective
+anisotropic force. Importantly, we also show that in order to achieve
+hydrostatic equilibrium configurations of magnetized matter, it is essential to
+account for both the local anisotropy effects as well as the anisotropy effects
+caused by a strong magnetic field. Otherwise, hydrostatic equilibrium is not
+achieved for magnetized stellar models.",2108.12436v1
+2021-11-03,Anisotropic magnetocaloric effect of CrI$_{3}$: A theoretical study,"CrI$_{3}$ is considered to be a promising candidate for spintronic devices
+and data storage. We derived the Heisenberg Hamiltonian for CrI$_{3}$ from
+density functional calculations using the Liechtenstein formula. Moreover, the
+Monte--Carlo simulations with the Sucksmith--Thompson method were performed to
+analyze the effect of magnetic anisotropy energy on the thermodynamic
+properties. Our method successfully reproduced the negative sign of isothermal
+magnetic entropy changes when a magnetic field was applied along the hard
+plane. We found that the temperature dependence of the magnetocrystalline
+anisotropy energy is not negligible at temperatures slightly above the Curie
+temperature. We clarified that the origin of this phenomenon is attributed to
+anisotropic magnetic susceptibility and magnetization anisotropy. The
+difference between the entropy change of the easy axis and the hard plane is
+proportional to the temperature dependence of the magnetic anisotropy energy,
+implying that the anisotropic entropy term is the main source of the
+temperature dependence of the free energy difference when magnetizing in a
+specific direction other than the easy axis. We also investigated the magnetic
+susceptibility that can be used for the characterization of the negative sign
+of the entropy change in the case of a hard plane. The competition of
+magnetocrystalline anisotropy energy and external magnetic field at low
+temperature and low magnetic field region causes a high magnetic susceptibility
+as the fluctuation of magnetization. Meanwhile, the anisotropy energy is
+suppressed at a sufficient magnetic field applied along the hard axis, the
+magnetization is fully rotated to the direction of the external magnetic field.",2111.02063v1
+2022-06-28,Turbulent magnetic helicity fluxes in solar convective zone,"Combined action of helical motions of plasma (the $\alpha$ effect) and
+non-uniform (differential) rotation is a key dynamo mechanism of solar and
+galactic large-scale magnetic fields. Dynamics of magnetic helicity of
+small-scale fields is a crucial mechanism in a nonlinear dynamo saturation
+where turbulent magnetic helicity fluxes allow to avoid catastrophic quenching
+of the $\alpha$ effect. The convective zone of the Sun and solar-like stars as
+well as galactic discs are the source for production of turbulent magnetic
+helicity fluxes. In the framework of the mean-field approach and the spectral
+$\tau$ approximation, we derive turbulent magnetic helicity fluxes using the
+Coulomb gauge in a density-stratified turbulence. The turbulent magnetic
+helicity fluxes include non-gradient and gradient contributions. The
+non-gradient magnetic helicity flux is proportional to a nonlinear effective
+velocity (which vanishes in the absence of the density stratification)
+multiplied by small-scale magnetic helicity, while the gradient contributions
+describe turbulent magnetic diffusion of the small-scale magnetic helicity. In
+addition, the turbulent magnetic helicity fluxes contain source terms
+proportional to the kinetic $\alpha$ effect or its gradients, and also
+contributions caused by the large-scale shear (solar differential rotation). We
+have demonstrated that the turbulent magnetic helicity fluxes due to the
+kinetic $\alpha$ effect and its radial derivative in combination with the
+nonlinear magnetic diffusion of the small-scale magnetic helicity are dominant
+in the solar convective zone.",2206.14152v2